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How to Measure Watts on Amplifier
How to Measure Watts on an Amplifier
How to measure watts on an amplifier
The term watt is a measuring unit. It was framed after a Scottish inventor named James Watt. With respect to a speaker or an amplifier, a watt is nothing but the measurement that helps in finding out the energy used by an amplifier or a speaker per second to convert them into sound.
One of the easiest ways to calculate watt is by using Ohm's law. It is one of the widely used electrical engineering formulae in the world today.
It is easy to measure watts of any electronic device if one has basic knowledge in this filed. The following are the simple steps to measure watts on an amplifier.
 - The first and foremost thing to do is to find out the amount of voltage used by the audio device while operating. This is not a very hard task because every electronic device comes with all the information about it in the package in which they are sold. If the information is not on the package, then it can be found in the user manual of the audio device. If the audio device is bought as a second-hand device and the information for the same is missing, it is easy to find about the same in PDF formats online. Note down the voltage of the device; this is crucial for the last step.
 - The second step is to find out the recommended amount of current or power that can pass through the wire of the audio device. This information will also be available in the above-mentioned documents. You need t0 note down the current of the audio device.
 - The last step is nothing but to calculate Ohm's law for power. The formula for the Ohm's law is P=V*I. In this equation P is power, V is voltage and I is current. The value of current and voltage that you have noted down in the first and second steps should be applied in the Ohm's law formula. The resulting answer is the wattage of a speaker or an amplifier.


text:
A Magnetic Sensor Utilizing an Avalanching Semiconductor Device
by A. W. Vinal
A new semiconductor device for sensing uniaxial magnetic fields has been realized. The device is basically a dual-collector open-base lateral bipolar transistor operating in the avalanche region, and is referred to as a Magnetic Avalanche Transistor. It exhibits high magnetic transduction sensitivity compared to traditional Hall-effect and conventional nonlinear magnetoresistive devices. Several hundred experimental devices have been designed, fabricated, and tested over the past two years. Many structural and some process parameters were varied. The magnetic sensitivity of a typical device was found to be proportional to substrate resistivity. A sensitivity of 30 volts per tesla was measured for devices which used 5-ohm-cm p-type substrates. The output signal measured between collectors is differential and responds linearly with field magnitude and polarity. A typical signal-to-noise ratio is 20,000 per tesla. The bandwidth is known to extend well beyond 5 MHz. The sensitive area is calculated to be on the order of 5 μm2. This communication describes the basic structure, fabrication, and characteristics for the magnetic avalanche transistor.

source: m-a-p/FineFineWeb


Take the 2-minute tour ×
I wonder how is this possible in groovy to start an array from the n element.
Look at the snippet :
static void main(args){
 if (args.length < 2){
 println "Not enough parameters"
 def tools = new BoTools(args[0])
 def action = args[1]
As you see am doing here a dynamic method invocation. The first 2 arguments are taken as some config and method name, the others I would like to use as method paramerts. So how can I do something like this :
Edited : If not possilbe in native groovy Java syntax will do it :
def newArgs = Arrays.copyOfRange(args,2,args.length);
share|improve this question
That System.exit(1) is pointless. Java isn't C. – Esko Mar 18 '12 at 19:28
add comment
1 Answer
up vote 3 down vote accepted
To remove items from the beginning of the args you can use the drop() method. The original args list is not changed:
Other option, like you are trying is to access from N element:
share|improve this answer
+1 for range notation. It is tidy and we already know we have >= 2 values. – David Mar 18 '12 at 20:40
add comment
Your Answer


text:
World's First Chemistry on a Chip "Chem Chip™". Interested industrialists within the energy, chemical or fuels space will find our Chemistry on a Chip "Chem Chip™" of interest at multiple strategic levels and within several time domains.
Chemistry on a Chip™ or "Chem Chip(s)™" are solid-state chemical cells that upgrade existing refinery and petrochemical plants to solid-state chemistry and de-couple their dependence on crude oil. Use cases for a Chem Chip™ include, "Refinery on a Chip™" and "Plant on a Chip™" for production of more than one carbon molecule.
Chem Chips are built with trillions of nanoscale spikes that concentrate the electrical field to enable 12 electron direct reactions. Think of this innovation as an industrial scale version of nature's enzymes that focus electron transfer. However, life in nature's mission is to live first and not make products. Our Chem Chip's mission is to make products first as it does not require biological life to run the reaction within such an intense electrical field created on the Chem Chips.
_TAG_ _TAG_ _TAG_ _TAG_ _TAG_ _TAG_ _TAG_ _TAG_.

source: openbmb/Ultra-FineWeb


above.
 «Calling flip_and_wait twice, that is, waiting twice for the grace period to complete»
 -> inaccurate. By doing flip_and_wait twice, we're actually waiting for a single grace period (by definition).
 Also, I would appreciate if you could please credit the sources of the graph and diagram you use in your article.
 Thanks,
 Mathieu Desnoyers
3,751
Ropes — Fast Strings
Most of us work with strings one way or another. There's no way to avoid them — when writing code, you're doomed to concatinate strings every day, split them into parts and access certain characters by index. We are used to the fact that strings are fixed-length arrays of characters, which leads to certain limitations when working with them. For instance, we cannot quickly concatenate two strings. To do this, we will at first need to allocate the required amount of memory, and then copy there the data from the concatenated strings.


Calculate bits and bytes
Discussion in 'Questions (Windows Mobile)' started by schimanski, Aug 29, 2008.
 1. schimanski
 schimanski Well-Known Member Licensed User
 Hello!
 I need to decode a UKSP-String (Ultra Short (kurz) String Police) for my application. The UKSP-String is a String with crlf+18 Bytes+crlf. Each Byte will save informations. For example: the first Byte is caluculated with:
 Byte1=CHR(128+(County*8)+(bit.AND(District,28))/4))
 County and District are decimal values. Now my question: Is there a way to decode the Byte1 in the Country and District? My first problem is to reverse the bitwise operation "bit.AND(District,28)".
 Thanks for answer...
 schimanski

 2. agraham
 agraham Expert Licensed User
 I think this does it. What is happening is that the 128 is packing to make the code printable, or at least non-zero. County is multiplied by 8 which effectively left shifts it three binary places leaving the values 0 to 7 free for the District. The District number is ANDed with binary 11100 (28) then divided by 4 which effectively right shifts the result to the the bottom three bit positions left clear by moving County left. As a result the decoded County can have any value but the decoded District can only have one of the eight values 0,4,8,12,16,20,24,28 or 0 to 7 if you don't undo the original divide by 4.
 Code:
 Sub Globals

 Dim County

 Dim District
 End Sub
 Sub App_Start
 Decode(
 128 + 3 * 8 + 12 /4)
 msg =
 "County - " & County & CRLF
 msg = msg &
 "District - " & District

 Msgbox(msg)
 End Sub
 Sub Decode(code)
 code = code -
 128
 District =
 4 * (code Mod 8' bottom three bits
 County = Int(Code / 8)
 End Sub

 Last edited: Aug 29, 2008
 3. schimanski
 schimanski Well-Known Member Licensed User
 Many thanks
 Thanks agraham for the fast answer!
 I think, that I begin to understand it.
 I will try now something with your code...
 :sign0060:

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text:
This year is already Sydney's wettest year on record, with more than 2.2 metres of rain having fallen since January.
Previously, Sydney's wettest year was 1950, when the total annual rainfall was 2.194 metres. This year's rainfall topped that figure at around 1pm on 6 October.
In an average year, Sydney only gets about 1.2 metres of rain.
2022 has been a truly exceptional year of rainfall in #Sydney. It only took 279 days to break the city's annual rainfall record of 2194mm from 1950, with annual data available back to 1859. _URL_
— Ben Domensino (@Ben_Domensino) October 6, 2022
With almost a quarter of the year left to go and wet conditions predicted to continue, 2022 is likely to be the wettest year on record in Sydney by a long margin, says Milton Speer at the University of Technology Sydney.
There are several reasons why it has been so wet, he says. One is that for the third year in a row, the east coast of Australia is experiencing a La Niña weather cycle, which attracts moist onshore winds from the Pacific Ocean.
Another is that there have been a series of low-pressure troughs associated with low-pressure systems that have "focused the rain for extended periods on Sydney and other parts of the coast", says Speer.
— Prof Simon de Graaf (@spdegraaf) October 6, 2022
In addition, a weather cycle called the Indian Ocean Dipole that affects countries around the Indian Ocean, including Australia, has recently moved into its negative phase, which is enhancing Sydney's rainfall even further.
Finally, climate change may be exacerbating the wet conditions by raising sea surface temperatures so that there is more evaporation and more moisture in the air to fall out again as rain, says Speer.
The deluge has already caused repeated flooding in Sydney, particularly in areas near the Hawkesbury and Nepean rivers, where residents have been evacuated four times this year.
The flooding damaged homes, shops and infrastructure, and four people have drowned.
Heavy rain is set to continue in Sydney and other parts of the state of New South Wales over the coming days, with flood warnings in place for 50 locations.
50 current FLOOD warnings across NSW ☔
6th October at 6pm
ADVICE – 36
WATCH & ACT – 14
EMERGENCY WARNING – 0
— NSW SES (@NSWSES) October 6, 2022


text:
Implementing Backtrack in Production System: A TMS based Approach .
Keywords: Production System languages, Dependency directed backtracking, Rete Net operations .
AbstractOPS5 is one of the most widely used Production System languages. The control strategies provided in OPS-like languages are extremely weak and consequently during problem solving, frequently dead-ends are encountered. We have made an attempt to perform dependency-directed backtracking within the framework of an OPS-like interpreter which employs a Truth Maintenance System for reasoning with past actions. The conditions for backtrack are characterised by the violation of a set of domain-specific constraints and signaled as contradictions in the Dependency Network (D-Net). We have developed a system, called OPS91, which comprises an enhanced match-select-act cycle operating on a D-Net as working memory. This cycle is explained with reference to the D-Net structure and the correlation between the D-Net and Rete-Net operations. The revision algorithm and null conflict set resolution strategy are detailed. The performance of the system is evaluated and broad guidelines on the programming strategy are presented.
How to Cite
Jaidev, M., Prakash, G., & Parameswaran, N. (2013). Implementing Backtrack in Production System: A TMS based Approach . Defence Science Journal, 43(2), 151-158. _URL_
Special Issue Papers
Copyright (c) 2016 Defence Science Journal
Where otherwise noted, the Articles on this site are licensed under Creative Commons License: CC Attribution-Noncommercial-No Derivative Works 2.5 India


Like many of his 1950s era space-piloting contemporaries, Rocky Jones was pretty popular with the kiddies. And why not? Despite its low budget and standard Space Ranger plots, every kid watching the 39 original episodes, which aired between 1953 and 1955 and were later recut and rereleased as a full-length feature, believed in the heroism and deep space adventures of the dashing star.
Richard Crane starred as the title character, a man whose record and reputation were so pristine, he was rarely (if ever) proven wrong or reprimanded by a superior.
Joined by his sidekick Winky (played by original Our Gang member Scotty Beckett), his on-again, off-again flame Vena Ray (played by Sally Mansfield), Rocky Jones's chief objective was to defeat the alien supergroup, the Officians (said to embody and reflect an anti-communist sentiment).
One of the series' distinguishing factors was that it was continuous, instead of episodic – so that it ran in a sort of soap opera-like sequence that never repeated or deviated from the developments of the plot before it.
Though he's rarely remembered today, Rocky Jones's legacy as a Space Ranger par excellence remains in tact. He even flirted with rekindled fame when his film work was briefly featured in two Mystery Science Theater 3000 episodes.


Preparing to hot-add SAS disk shelves
Preparing to hot-add a SAS disk shelf involves downloading documents as well as the disk drive and disk shelf firmware.
Before you begin
Note: A mix of IOM12 modules and IOM6 modules is supported within the same stack if your system is running a supported version of ONTAP. To establish whether your version of ONTAP supports shelf mixing, refer to the Interoperability Matrix Tool (IMT).NetApp Interoperability If your version of ONTAP is not supported and you cannot upgrade or downgrade the IOM modules on the existing stack or the new shelf that is to be added to a supported combination of IOM modules, you need to do one of the following:
 - Start a new stack on a new SAS port (if supported by the bridge-pair).
 - Start a new stack on an additional bridge-pair.
 1. Download or view the following documents from the NetApp Support Site:
 2. Verify that the disk shelf you are hot-adding is supported.
 3. Download the latest disk and disk shelf firmware:
 Note: In this step, you are only completing the download portion of the instructions provided in the links. You need to follow the steps found in the Hot-adding a disk shelf section for installing the disk shelf.
 1. Download the disk firmware and make a copy of the disk firmware instructions for reference later.
 2. Download the disk shelf firmware and make a copy of the disk shelf firmware instructions for reference later.


text:
Special offer original Price £10.95 Now £2.50.
Seven meditations on the creation narrative of Genesis 1-2.3 use the text as a starting point for the developing life of prayer. Each chapter concludes with a summary and seven suggestions for ways of praying. These meditations are suitable for individuals or groups as a lent course.
Let There Be Light
- Author: Angela Tilby
- Publisher: D.L.T


text:
- 1 Who was the real Airwolf pilot?
- 2 Who flew the helicopter in Airwolf?
- 3 Is there a real helicopter like Airwolf?
- 4 Why was Airwolf Cancelled?
- 5 What helicopter was Kobe in?
- 6 Was Airwolf used in the A team?
- 7 What happened to the original Airwolf helicopter?
- 8 Is Blue Thunder a real helicopter?
- 9 What is the fastest helicopter in the world?
- 10 What is the fastest helicopter in the US military?
- 11 Can a helicopter fly to the top of Everest?
- 12 Can helicopters go supersonic?
Who was the real Airwolf pilot?
Airwolf is a drama loaded with action and adventure thanks to its true star – a science-fiction helicopter named Airwolf. Nicknamed "The Lady," Jan-Michael Vincent plays its reclusive pilot Stringfellow Hawke and veteran actor Ernest Borgnine is co-pilot Dominic Santini.
Who flew the helicopter in Airwolf?
Pilot Scott Meher, 46, of Los Angeles, flown by air ambulance to Henry Mayo Newhall Memorial Hospital, was in fair condition with a concussion and abrasions, nursing supervisor Rose Morelli said. ″Members of the crew rushed over and pulled out the pilot, then the helicopter burst into flames.
Is there a real helicopter like Airwolf?
The answer to that is a resounding "yes." The aircraft seen on the television show is a Bell 222 helicopter painted black and outfitted with film props and spruced up with special effects. The Bell 222 was designed in the late 60s and first flew in 1976. In a way, it was fitting that the Bell 222 was used as Airwolf.
Why was Airwolf Cancelled?
Scandal dogged Mr. Vincent in the 1980s. He was known to abuse alcohol and cocaine and was accused of getting into bar fights; he narrowly avoided jail in 1986 by entering a monthlong drug rehabilitation program after breaking probation related to an earlier drunken-driving conviction. CBS canceled "Airwolf" that year.
What helicopter was Kobe in?
The helicopter that Kobe Bryant was on was a Sikorsky S-76B. A model frequently used for VIP passengers, search and rescue missions, and air ambulances.
Was Airwolf used in the A team?
Today, we proudly share the Best Vehicle Guest Appearances from the A-Team The Santini Air Jetranger (N2044C) from Airwolf graced us with it's presence in a number of season 2 episodes. During season two's 2-part episode "When You Comin' Back Range Rider", a familiar '80s companion graced us with an appearance.
What happened to the original Airwolf helicopter?
The actual helicopter used in the four series however met a tragic end. After filming ended Airwolf, a modified twin-engined Bell 222, was stripped of her 'futuristic, advanced weapons systems' and sold off. Transported from California to Germany it began a second career operating as an air ambulance.
Is Blue Thunder a real helicopter?
Blue Thunder is the helicopter in the 1980s American titular film and television series. The aircraft itself was a modified Aérospatiale Gazelle helicopter. After the film and TV series was made, both helicopters were sold to Michael E. Grube, an aviation salvage collector in Clovis, New Mexico.
What is the fastest helicopter in the world?
Sikorsky X2 – 299 mph; 481 km/h; 260 knots
The Sikorsky X2 now holds the record for the fastest helicopter in the world.
What is the fastest helicopter in the US military?
According to AirForce-Technology.com, the fastest helicopter in military service is the CH-47F Chinook, which has a top speed of 195 mph.
Can a helicopter fly to the top of Everest?
Helicopters can fly higher than the summit of Everest but landing to take on a passenger or body is dangerous. According to an interview with climber and helicopter pilot Simone Moro, the Fishtail helicopters are rated to reach an altitude of 23,051'/7026m but have flown as high as 7400m.
Can helicopters go supersonic?
A supersonic helicopter is simply not possible due to a flight characteristic known as "Dissymmetry Of Lift," (also known as "retreating blade stall"). When the rotor blades are turning, think of it as as a disc. The fuselage (or body of the helicopter) simply hangs by the rotor-mast at it's center of gravity.


text:
Seasonal and diurnal variations in moisture, heat and CO2 fluxes over a typical steppe prairie in Inner Mongolia, China
Abstract. In order to examine energy partitioning and CO2 exchange over a steppe prairie in Inner Mongolia, China, fluxes of moisture, heat and CO2 in the surface layer from June 2007 through June 2008 were calculated using the eddy covariance method. The study site was homogenous and approximately 1500 m×1500 m in size. Seasonal and diurnal variations in radiation components, energy components and CO2 fluxes are examined. Results show that all four radiation components changed seasonally, resulting in a seasonal variation in net radiation. The radiation components also changed diurnally. Winter surface albedo was higher than summer surface albedo because during winter the snow-covered surface increased the surface albedo. The seasonal variations in both sensible heat and CO2 fluxes were stronger than those of latent heat and soil heat fluxes. Sensible heat flux was the main consumer of available energy for the entire experimental period. The energy imbalance problem was encountered and the causes are analyzed.


text:
The most common biomechanical explanation for the chin is that it acts as a buttress against masticatory stress. However, recent evidence suggests that this hypothesis is unlikely [...] More recently Ichim et al. (2007) have suggested that speech production is associated with mechanical stresses acting on the mandibular symphysis due to tongue and orofacial muscle activity. Thus, they argue that the chin is an adaptive response to resist stresses caused by oblique contractions of the genioglossus muscles during speech. Computer simulations provide results that are consistent with the orofacial stress hypothesis (Ichim et al., 2007), but this hypothesis has yet to be fully tested.
A less well-established adaptive hypothesis, but one worth considering, is that chin shape variation is a consequence of sexual selection (e.g., Hershkovitz, 1970). Psychological studies of facial attractiveness suggest that a ''broad chin'' in males is correlated with social dominance, which some females may prefer in a potential mate
Our study provides the first quantitative evidence of sexual dimorphism in chin shape among a geographically diverse sample of modern humans. The presence of sexual dimorphism appears to refute mechanical explanations of the chin that preclude sexual dimorphism, such as the masticatory and orofacial stress hypotheses (e.g. Daegling, 1993; Ichim et al., 2007).
While the presence of sexual dimorphism is consistent with the hypothesis that sexual selection influences variation in chin shape, the degree of overlap between males and females requires further explanation. It is safe to say that the male chin pales in comparison to the more exaggerated ornaments found in other animals, such as the large and colorful tail of the peacock (Pavo cristatus) (Petrie, 1991). The modest contrasts in male and female chin shape indicated by our data (see Fig. 4) do not seem to fit a runaway process of selection driven by female choice (Fisher, 1958). We suggest there are at least two possible explanations for this pattern.
One hypothesis for why male chin shape is not more exaggerated is that some females may avoid mating with extremely aggressive males
Second, the large amount of overlap in male and female chin shape may be due to regional differences inchin shape dimorphism (see Fig. 6). Regional differencesin the level of dimorphism would tend to inflate within-sex variance in the pooled human sample, thereby reducingthe probability of finding between-sex differences.
Sexual dimorphism in chin shape: Implications for adaptive hypotheses
Zaneta M. Thayer, Seth D. Dobson
The chin, or mentum osseum, is one of the most distinctive anatomical traits of modern humans. A variety of hypotheses for the adaptive value of the chin have been proposed, ranging from mechanical stress resistance to sexual selection via mate choice. While the sexual selection hypothesis predicts dimorphism in chin shape, most biomechanical hypotheses preclude it. Therefore determining the presence or absence of significant sexual dimorphism in chin shape provides a useful method for differentiating between various adaptive hypotheses; however, this has yet to be done due to a lack of quantitative data on chin shape. The goals of this study are therefore: (1) to introduce a new method for quantifying chin shape and (2) to determine the presence or absence of sexual dimorphism in chin shape in a diverse sample of modern humans. Samples were drawn from recent human skeletal collections representing nine geographic regions. Outlines of mentum osseum contours were quantified using elliptical Fourier function analysis (EFFA). Fourier coefficients were analyzed using principal components analysis (PCA). Sexual dimorphism in chin shape was assessed using PC loadings in the pooled geographic sample, and statistically significant differences were found. These findings provide the first quantitative, morphologically based evidence in support of adaptive hypotheses that predict dimorphism in chin shape, including the sexual selection hypothesis.

source: HuggingFaceFW/fineweb-edu


How to Fix the Craigslist.org "An Error Has Occurred When Clicking Reply Button" Issue
If you are a frequent user of Craigslist.org, you might have encountered an annoying issue when trying to reply to a listing. The message "An error has occurred when clicking the reply button" pops up, preventing you from communicating with the seller or buyer. This issue can be frustrating, especially when you need to follow up on an important inquiry or negotiate a deal.
Fortunately, there are several troubleshooting steps that you can take to resolve this problem and get back to using Craigslist.org smoothly. First, check your internet connection to ensure that it is stable and working properly. A weak or unreliable internet connection can often cause errors like the one you are experiencing.
If your internet connection is fine, try clearing your browser's cache and cookies. Over time, these files can accumulate and cause conflicts with websites like Craigslist.org. Clearing them out can help resolve any underlying issues and refresh your browsing experience.
Another step you can take is to disable any browser extensions or add-ons that might be interfering with the functioning of Craigslist.org. Sometimes, these extensions can conflict with certain website features and prevent you from clicking the reply button. Temporarily disabling them can help identify the cause of the problem.
If none of these steps resolve the issue, try accessing Craigslist.org using a different browser. It is possible that the problem is specific to the browser you are currently using. Switching to a different browser can help determine whether this is the case or not.
By following these troubleshooting steps, you can hopefully resolve the "An error has occurred when clicking the reply button" issue on Craigslist.org and continue using the platform without any interruptions. Remember, if the problem persists, it is advisable to reach out to Craigslist.org's support team for further assistance.
How to Fix the Craigslist.org "An Error Has Occurred When Clicking Reply Button" Issue
If you are encountering the "An Error Has Occurred When Clicking Reply Button" issue on Craigslist.org, there are several steps you can take to resolve the problem. This error occurs when users try to reply to listings on Craigslist and are unable to do so due to an error in the system. Follow the troubleshooting steps below to fix the issue:
 1. Clear your browser cache and cookies: The first step to fixing the issue is to clear your browser cache and cookies. These files can sometimes become corrupted or outdated, causing errors on websites like Craigslist. To clear your cache and cookies, go to your browser settings and look for options to clear browsing data. Make sure to select "cache" and "cookies" and then click on the "Clear" or "Delete" button.
 2. Disable browser extensions or add-ons: Sometimes, browser extensions or add-ons can interfere with the functioning of websites, including Craigslist. To check if this is the case, disable all your browser extensions or add-ons and then try to reply to a Craigslist listing again. If the error no longer occurs, it means that one of the extensions or add-ons was causing the problem. Enable them one by one to identify the culprit and either remove or update it.
 3. Update your browser to the latest version: Outdated browsers can also cause errors on websites. Check if there are any available updates for your browser and install them. Updating your browser to the latest version can often resolve compatibility issues and improve overall performance. Once you have updated your browser, try to reply to a Craigslist listing again and see if the error persists.
By following these steps, you should be able to fix the "An Error Has Occurred When Clicking Reply Button" issue on Craigslist.org. If the issue still persists, you may want to reach out to Craigslist support for further assistance.
Identifying the Problem
When encountering the "An Error Has Occurred When Clicking Reply Button" issue on Craigslist.org, it is important to understand the underlying problem in order to find a solution. The error message indicates that there is a problem with accessing the reply function on the website. This can be frustrating, especially if you are trying to respond to an ad or communicate with a seller.
The problem may be caused by various factors, including technical issues, browser settings, or even user error. It is essential to identify the specific cause of the error to effectively troubleshoot and resolve the issue. By understanding the root of the problem, you can determine the appropriate steps to take and prevent similar errors from occurring in the future.
Possible causes of the error
When encountering the "An Error Has Occurred When Clicking Reply Button" issue on Craigslist.org, there are several potential causes to consider:
 - Browser compatibility: The error may be caused by compatibility issues between the browser you are using and Craigslist.org. Different browsers may interpret and handle website features differently, leading to errors when attempting to click the reply button.
 - Outdated browser version: Using an outdated version of your browser can also trigger the error. New updates and patches are released regularly to fix bugs and security vulnerabilities, so it's important to keep your browser up to date.
 - Internet connectivity: Unstable or slow internet connectivity can interfere with the proper functioning of websites, including Craigslist.org. If your internet connection is weak or unreliable, it may prevent the reply button from functioning correctly.
 - Browser extensions or add-ons: Certain browser extensions or add-ons can conflict with the functionality of Craigslist.org, causing the error to occur. These extensions may modify or block certain elements of the website, including the reply button.
 - Cache and cookies: Temporary files and cookies stored in your browser's cache can sometimes become corrupted or outdated, causing various website errors. In the case of Craigslist.org, this can include issues with the reply button.
It's important to consider and address these possible causes when troubleshooting the "An Error Has Occurred When Clicking Reply Button" issue on Craigslist.org. By identifying the root cause, you can implement the appropriate solution to resolve the error and ensure smooth functionality of the website.
Common symptoms of the error
 - When clicking the "Reply" button on Craigslist.org, users may encounter an error message.
 - The error message may vary, but it commonly includes phrases like "An error has occurred" or "Unable to perform the requested action".
 - Users may notice that the "Reply" button is unresponsive or does not function as expected.
 - Some users may experience the error consistently, while others may encounter it sporadically.
 - The error may occur on different browsers, including Google Chrome, Mozilla Firefox, Safari, or Internet Explorer.
 - Attempting to refresh the page or open the listing in a new tab or window may not resolve the error.
 - Users may become frustrated or confused, especially if they rely on Craigslist for buying or selling items.
 - The error can disrupt the normal flow of communication between buyers and sellers on the platform.
 - Repeatedly encountering the error may lead users to seek solutions or troubleshooting steps to fix the issue.
Troubleshooting Steps
Troubleshooting Steps
If you are experiencing the "An Error Has Occurred When Clicking Reply Button" issue on Craigslist.org, there are several troubleshooting steps you can follow to resolve the problem. Here are the steps you can take:
 1. Step 1: Clear your browser cache and cookies
 2. Clearing your browser cache and cookies can help resolve any temporary issues that may be causing the error. Here's how you can do it:
 - For Google Chrome:
 - Click on the three-dot menu icon in the top right corner of the browser.
 - Select "More tools" and then click on "Clear browsing data".
 - In the popup window, select the time range and the types of data you want to delete.
 - Click on the "Clear data" button to clear your cache and cookies.
 - For Mozilla Firefox:
 - Click on the hamburger menu icon in the top right corner of the browser.
 - Select "Options" and then go to the "Privacy & Security" tab.
 - Scroll down to the "Cookies and Site Data" section and click on the "Clear Data" button.
 - In the popup window, select the types of data you want to delete and click on the "Clear" button.
 - For Microsoft Edge:
 - Click on the three-dot menu icon in the top right corner of the browser.
 - Go to "Settings" and then click on "Choose what to clear" under "Clear browsing data".
 - Select the types of data you want to delete and click on the "Clear" button.
 3. Step 2: Disable browser extensions or add-ons
 4. Sometimes browser extensions or add-ons can interfere with the functionality of websites, including Craigslist.org. To check if this is the cause of the error, you can disable your browser extensions or add-ons. Here's how you can do it:
 - For Google Chrome:
 - Click on the three-dot menu icon in the top right corner of the browser.
 - Hover over "More tools" and then click on "Extensions" in the submenu.
 - Disable any extensions you have installed by toggling off the switch next to each extension.
 - For Mozilla Firefox:
 - Click on the hamburger menu icon in the top right corner of the browser.


text:
Skip to Main Content
An educational television network using UHF transmissions from aircraft has been suggested as a means to provide improved classroom instruction to schools throughout the country. Initial airborne tests will begin in 1960. As a step in the evaluation of such a network, calculations have been made which describe the coverage from an airborne station in the presence of interference from other stations. The results should be useful in determining the equipment and channel requirements of a nation-wide network. These requirements will be compared with those necessary to provide equivalent coverage from ground-based UHF stations.


Need a special offer?Find out if your project fits.
+
All documentation
 - API Reference for older versions
 - clearXMLACache
 clearXMLACache(proxyURL: String, databaseId: String, callbackHandler: Function, cubeId: String, measuresGroupId: String, username: String, password: String)
 [starting from version: 2.2]
 API call that requests Microsoft Analysis Services to clear the cache. Please visit official documentation from Microsoft for more details.
 Parameters
 Parameter/TypeDescription
 proxyUrl
 String
 The path to proxy URL to the Microsoft Analysis Services data source.
 databaseId
 String
 The ID of the database on the current connection.
 callbackHandler
 Function
 optional A JS function that will be called when the component completes the request.
 In case of success, the following object will be returned: { complete: true, response: response from SSAS }.
 In case of failure, the object will contain only one property: { complete: false }.
 cubeId
 String
 optional Cube ID.
 measuresGroupId
 String
 optional Alternatively, you can specify a path of a child object, such as a measure group, to clear the cache for just that object.
 username
 String
 optional The name of a user account on the server. This parameter is necessary to complete the authentication process.
 password
 String
 optional The password to a user account on the server. This parameter is necessary to complete the authentication process.
 Example
 function clearCache() {
 flexmonster.clearXMLACache(
 // replace with your proxyUrl
 "_URL_
 // replace with DatabaseID
 "Adventure Works DW 2008",
 function (res) {
 // check response
 console.log(res);
 }
 );
 }
 clearCache();
 Open the example on JSFiddle.


text:
Jump to navigation Jump to search
|The Simple English Wiktionary has a definition for: waterhole.|
|Wikimedia Commons has media related to watering holes.|
A waterhole or water hole is a depression in the ground in which water can collect.
Waterhole or water hole may also refer to:
- Water hole (radio), an especially quiet region of the electromagnetic spectrum
- The Water Hole, a 1928 Western film
- Waterhole No. 3, a 1967 Western comedy film, a comic remake of The Good, the Bad, and the Ugly
- Watering hole attack, a computer attack strategy
Related pages[change | change source]
- Water well, an excavated hole that is dug to provide water
| This disambiguation page lists articles associated with the title Waterhole.
If an internal link led you here, you may wish to change the link to point directly to the intended article.


text:
In November 2011, the State Administration for Industry and Commerce ("SAIC") of the People's Republic of China (the "PRC") released the Administrative Measures for the Registration of Debt-for-Equity Swaps (the "Swap Measures") (公司债权转股权登记管理办). These Swap Measures took effect from 1 January 2012.
The Swap Measures set out the policy framework for the conversion of debt owed by a limited liability company established in the PRC, into equity in that company ("debt-forequity swap").
The Swap Measures
The Swap Measures make clear that debt-forequity swaps are permitted in the PRC as a form of non-cash capital contribution to a company registered in the PRC.
The Swap Measures contemplate that the following categories of debt may be swapped into equity:
- debt arising from a contract between the creditor and the company where the creditor does not contravene prohibitory provisions of PRC laws and regulations;
- debt that have been approved by courts; and
- debt listed in the reorganisation plans or in reconciliation (settlement) agreements approved by the relevant courts.
Process for Implementing the Debt-For- Equity Swap
The procedures for effecting a swap are as yet unclear and will be subject to further regulations issued by the PRC government or clarifications through Court rulings. It is however clear that to effect a swap, the following will be required:
- The debt to be swapped into equity has to be
Prior to undertaking the swap, an approved assets valuation institution, generally referring to licensed audit or valuation firms in the PRC, will have to be appointed to value the debt. The terms of the swap must be such that the debt is converted at or below its appraised value.
- Non-Cash Capital Contribution
The sum of the appraised capital contribution of invested debt-for-equity swap and the appraised capital contribution of other non-monetary properties is not to exceed seventy percent (70%) of the registered capital of the company.
- Capital Verification
Capital contribution through debt-forequity swaps must be verified by a qualified capital verification institution that will issue a certificate (the "Valuation Certificate") specifying the following:
- basic information of the debt, including the time when such debt occurred, the name of title of the concerned parties, the subject matter of the contract and the fulfillment of obligations attached to the debt;
- valuation of the debt, including the name of the valuation institution, the document number of the Valuation Certificate, the benchmark date of the valuation, and the verified value;
- the progress of the debt-for-equity swap, including the conclusion of a debt-for-equity agreement, the creditor's exemption of the Company's debt;
- The accounting documents demonstrating relation to the debt cancellation; and
- the approval circumstances of the debt-for-equity swap if the approval thereof is required by law.
- Allocation of Creditors' rights
In the event of competing claims by more than one creditor, the Swap Measures sets out a process of allocation of the converted equity between the creditors.
- Debt in a Foreign Invested Company
A swap of debt into equity in a wholly foreign owned company or a sino foreign joint venture is subject to additional approvals by the authorities with regulatory authority over foreign investments.
The issue of the Swap Measures make clear the viability of PRC established companies issuing convertible instruments as a means of fund raising, and provides an additional means of investment in PRC companies. The actual procedures for effecting the swaps will have to wait further rulings in Court and implementing regulations or rulings.
This update is provided to you for general information and should not be relied upon as legal advice.


European Network In CHEmical Ecology: translating the language of life into sustainability (E-NICHE)
Program
COST

Cifru
CA22102
Perioada de realizare
2023-2027
Rezumat
E-NICHE will help unify the different branches of chemical ecology (CE) by bringing together researchers who study natural compounds that can act as semiochemicals (i.e., communication signals). At present, collaborations among these researchers are limited because CE is an extremely fragmented field. E-NICHE will foster partnerships between (a) scientists studying aquatic and terrestrial ecosystems; (b) natural products chemists, biochemists, and ecologists; (c) vertebrate biologists and entomologists; (d) plant and animal biologists; (e) zoologists and molecular biologists; and (f) neurobiologists and microbiologists. Their interactions will generate original ideas and perspectives while simultaneously meeting societal needs, a challenge that involves the creation of new chemical formulations, novel molecules, and innovative applications for natural compounds. This work will be nourished by a deeper understanding of the living world through the lens of chemical mediation, the main system of biological communication. It will also aim to prevent the loss of the chemical biodiversity found in nature, under threat because of global changes. Consequently, E-NICHE's overarching objective is to establish a strong, extended European CE network that catalyses international, interdisciplinary, and cross-sectoral exchanges with a view to building knowledge and intergenerational sustainable development solutions. Via the new network created by E-NICHE, researchers will broaden their breadth of knowledge, define new research directions, and transform their discoveries into pioneering solutions.


text:
Living history celebration explores secret behind Powder Valley Nature Center name
St. Louis — Just what is in a name? Today, Powder Valley Conservation Nature Center in Kirkwood is an ideal place to peacefully enjoy nature.
But the origins of its name come from war.
As part of the Nature Center's year-long 20th anniversary celebration, Powder Valley will present a living history weekend Friday and Saturday, May 13 and 14, for a special two-day program called "Blast to the Past: A History Festival". Visitors will explore the history behind the Powder Valley name and enjoy a fascinating and educational glimpse into the past of the area.
"Although we've only been here 20 years," said Assistant Nature Center Manager Catherine McGrane, "this land has its own history."
The powder was gunpowder. The "valley" was a series of caves that once existed under what is now I-270. According to McGrane, during the Civil War, Federal forces stockpiled gunpowder in the caves to use in blowing up bridges should the Confederate army attempt to invade St. Louis by way of the Meramec River.
The celebration begins Friday night from 7 to 9 p.m. with presentations by three first-person interpreters, each representing a different Civil War-era perspective: a Union soldier, Confederate soldier and a slave. A reception will follow the program allowing visitors to talk with each interpreter.
McGrane thinks it will be an ideal way to get a feel for what people were really like back then. "It's one thing to stand and talk about it," said McGrane, "it's another thing to become the person. Your audience can relate better and be more passionate about it."
The exploration of the past continues on Saturday from 10 a.m. to 2 p.m. with events at both the Nature Center and nearby Emmenegger Nature Park. A free shuttle will allow guests to park at either site and visit both.
A variety of historic crafts will be demonstrated such as candle making, storytelling, wood carving and fire starting. Civil War re-enactors will be encamped at Emmenegger Nature Park. Local historian and musician Dee Ban will perform and interpret 19th-century music. A Civil War doctor will display medical instruments of the era. Participants will even have a chance to try their hand at historical skills like archery and the atlatl, an ancient spear-throwing device.
All events during Powder Valley Nature Center's "Blast to the Past: A History Festival" weekend are free of charge and open to all ages. Reservations are required for the Friday evening program, but not for the events on Saturday. For reservations and more information, call _PHONE_.
Powder Valley Conservation Nature Center is located 11715 Cragwold Road, near the intersection of I-44 and I-270 in Kirkwood. Emmenegger Nature Park is also off Cragwold Road, just west of the Nature Center.
The Nature Center will continue to feature special events each month this year to commemorate its 20th Anniversary. Powder Valley first opened its doors to the public in October 1991.


text: Abstract:One major goal of functional genomics has been to identify and analyze molecular interactions in a cellular context to better understand the underlying design principles and mechanisms. To investigate into a PPI network from both topological and functional points of view, this work proposes a methodology that exploits ontology-based biological knowledge for network analysis. To speed up the procedure, an agent-based framework is also presented for supporting distributed computing. The preliminary results show that through the knowledge obtained from gene ontology, our work in analyzing building blocks of PPI networks can give a higher resolution than that of previous ones. Also our agent-based framework can successfully speed up the task of network analysis in an adaptive manner.


$.
The case r=0 can also be treated by hand and will be ignored. Now, we double-count. Observe that each $r$-element set in ${\mathcal D}$ has $r$ "children" as $r-1$-element subsets of ${\mathcal D}$, by removing one of the r elements from that set. On the other hand, each $r-1$-element set can have at most $n-r+1$ "parents", and so
$$ r f_r \leq (n-r+1) f_{r-1}.$$
(EDIT: Actually we didn't need to remove the r=0 case if we adopted the convention $f_{-1}=0$ here.)
In particular, if $r > \frac{n+1}{2}$, then $f_r < f_{r-1}$ we could remove both the r and r-1-element sets from the downset and again increase the sum; so we have $r \leq \frac{n+1}{2}$. In fact the same argument shows that, by changing the extremum ${\mathcal D}$ if necessary, we may assume that $r < \frac{n+1}{2}$, thus (since $n$ is 3 mod 4 and r is even) $r \leq \frac{n-3}{2}$. In other words, every element of ${\mathcal D}$ has cardinality at most $(n-3)/2$.
Now we flip the downset to look at the complementary downset ${\mathcal D}' := \{ A \in [n]: [n] \backslash A \not \in {\mathcal D} \}$. As n is odd, we have $\sum_{A \in {\mathcal D}'} (-1)^{|A|} = \sum_{A \in {\mathcal D}} (-1)^{|A|}$, and so ${\mathcal D}'$ is also an extremiser. Thus, by the above argument, every element of ${\mathcal D}'$ has cardinality at most $(n+1)/2$. Equivalently (as $n$ is odd), ${\mathcal D}$ contains every element of cardinality at most $(n-3)/2$. Combining this with the previous analysis, we see that the extremum is attained at the set consisting precisely of all subsets of [n] of cardinality at most $(n-3)/2$, which gives the required value of $F_+(n)$.
share|improve this answer
In retrospect, this would have been a great mini-polymath problem. Ah well. :-) – Terry Tao Jul 9 '12 at 18:50
Wha do you mean "would have been"? Wasn't it? Also, do I get my Tao number now, or do I have to wait five business days? Gerhard "Happy To Have Rendered Assistance" Paseman, 2012.07.09 – Gerhard Paseman Jul 9 '12 at 18:59
Well, I guess it was in a de facto sense, if not in a premeditated sense. I unfortunately don't have a strong enough application for the bound in order to merit publication, though; I came across the question because I was wondering about how to bound partial divisor sums of the Mobius function, and then felt that it had enough independent interest to pose here, but the bounds don't seem to make any dramatic dents in the bounds for other number-theoretic quantities, alas. But it's still great that the problem seems to be solved, it may be of use at some future date... – Terry Tao Jul 9 '12 at 19:23
Well, in the meantime, I think I'll submit the sequences F_+ and F_to OEIS. Whether this will count as a "publication" for the purposes of bibliographic metrics, I leave to the reader. – Terry Tao Jul 9 '12 at 20:08
I think this question and its solution within 3 hours is a typical example of how much more efficient people can get when collaborating via mathoverflow. – Christian Stump Jul 10 '12 at 6:41
I tried it using linear integer programming for the first few values of $n$, with the following results.
$$ \matrix{ n & min & max\cr 1 & 0 & 1\cr 2 &-1 & 1\cr 3 & -2 & 1\cr 4 & -3 & 3\cr 5 & -4 & 6\cr 6 & -10 & 10\cr 7 & -20 & 15\cr 8 & -35 & 35\cr 9 & -56 & 70\cr} $$
These sequences do not appear to be in the OEIS.
share|improve this answer
The bounds for even $n$ look interesting. Does the pattern (i.e. min = - max) continue for further even $n$? – Michael Albanese Jul 9 '12 at 16:59
So far this is consistent with the tentative conjecture proposed above, which more explicitly asserts that the bounds should be $\pm \binom{n-1}{n/2}$ when n is even, between $−\binom{n-1}{(n-1)/2}$ and $\binom{n-1}{(n+1)/2}$ when n is 3 mod 4, and between $-\binom{n-1}{(n+1)/2}$ and $\binom{n-1}{(n-1)/2}$ when n is 1 mod 4. (Thus, for instance, the conjecture would assert -126 and +126 for n=10, -252 and 210 for n=11, and so forth, as both bounds snake down the middle of Pascal's triangle.) – Terry Tao Jul 9 '12 at 17:29
For even $n$ it looks like $\max = -\min = {n \choose {n/2}}/2$, which is obtained taking all the subsets of cardinality $< n/2$ or $> n/2$. – Robert Israel Jul 9 '12 at 17:31
I can't believe I didn't see this before, but it is trivial that the max and min will be negations of each other in the n even case, because the reflected complement of a downset is again a downset. – Terry Tao Jul 9 '12 at 17:44
_USER_: Nice observation! Indeed, since one can slice an n-dimensional downset into two n-1-dimensional downsets, and the alternating sum of the former is the difference of the two for the latter, I think this shows that the conjecture for even n is implied by the conjecture for n-1, and one of the two bounds for odd n is implied by the bound for n-1. So it's only the smaller of the two bounds in odd n that needs proof... – Terry Tao Jul 9 '12 at 18:13
Here is a simple proof which should give exact optimizers for "most" choices of n mod 4 and max/minimizing; and, near-sharp values for the remaining cases. I'll do it for upsets instead of downsets.
Identify the discrete cube with $\{-1,1\}^n$ and let $f : \{-1,1\}^n \to \{0,1\}$ be the indicator of $\mathcal{D}$ which is monotone since $\mathcal{D}$ is an upset. Up to a factor of $2^n$ we are trying to min/maximize $E_x[f(x) \chi(x)]$, where $x$ is uniformly random on the cube and $\chi(x) = \prod_{i=1}^n x_i$. Let $1 \leq j \leq n$ be uniformly random and let $x^{(j)}$ denote $x$ with its $j$th coordinate negated. Since $x^{(j)}$ is also uniformly distributed,
$E_x[f(x) \chi(x)] = E_{x,j}[\frac{f(x) \chi(x) + f(x^{(j)})\chi(x^{(j)})}{2}] = E[\chi(x)\frac{f(x)-f(x^{(j)})}{2}]$
where we used $\chi(x^{(j)}) = -\chi(x)$. Thus in absolute value, the quantity is at most
$E[\bigl|\frac{f(x)-f(x^{(j)})}{2}\bigr|] = \frac{1}{2n}E_x\left[\sum_{i=1}^n \bigl|f(x)-f(x^{(i)})\bigr|\right] = \frac{1}{2n}E\left[\sum_{i=1}^n f(x)x_i\right]$,
where the last step uses that $f$ is monotone. But
$\frac{1}{2n}E\left[\sum_{i=1}^n f(x)x_i\right] = \frac{1}{2n} E\left[f(x)(\sum_{i=1}^n x_i)\right]$
is clearly maximized among $


text:
CHARLESTON, W.Va. -- Relax, anglers. If you catch a fish in West Virginia and think it might be one of those nasty northern snakeheads you've heard about, chances are it's not.
It's almost certainly a bowfin - a species that has prowled the depths of Mountain State waters since before the last Ice Age.
"We've gotten calls from people who think they have caught snakeheads, but really what they had caught were bowfins," said Scott Morrison, a district fisheries biologist for the state Division of Natural Resources. "We've never had a confirmed sighting of a snakehead in West Virginia."
Maryland and Virginia fisheries officials have been trying to eradicate snakeheads in tributaries of Chesapeake Bay, where the species has become established. Authorities became aware of the species in 2002 when a fisherman caught one from a pond in Crofton, Md.
Maryland law enforcement officers discovered that a local man had purchased two adult snakeheads from a New York market and had released them into the pond. The pond was drained and the snakeheads were destroyed, but the incident put officials on high alert.
A 2004 search found an established population of snakeheads in the Potomac River between Great Falls and the Chesapeake Bay. Fisheries experts believe the fish are restricted to that single stretch of river by the presence of the falls upstream and the salinity of the bay downstream.
Even so, West Virginia officials have been on the lookout for snakeheads ever since. If the species ever gets established upstream from Great Falls, it could then migrate upstream into West Virginia's Cacapon and South Branch rivers.
As awareness of snakeheads has increased, so have reports from anglers who believe they might have caught them.
Morrison said all those fish turned out to be bowfins. To help fishermen distinguish snakeheads from bowfins, DNR officials had a graphic created, and have posted the graphic on the agency's website.
"The easiest way to tell the two species apart is to look at the anal fin - the long, non-paired fin on the fish's underside," Morrison said. "In the snakehead, that fin is very, very long. It's more than half the length of the dorsal fin, which is also very long.


Sasha and Rhys initially began growing vegetables because they wanted to
teach themselves skillsthey started out as homesteaders who were preparing for self sufficient sustainability and wanting to live the good life.
Sasha, who is originally from the city in the South West of America, couldn't
get enough of the country life and Rhys, who grew up on a beef farm outside of Lismore, was more than happy to return to his roots.
But they quickly learned that love for the land wouldn't be enough to pay the mortgage at the end of the day. So the doomsayer and the city slicker started a farm.
Today Green Goddess Farm is on its 11th season of growing certified organic fruit and vegetables for the Northern Rivers and surrounds. They place high emphasis on quality nutrient dense produce, soil health, and regenerative farming. They grow a diverse range of seasonal vegetables and their mixed orchard of apples, kiwi fruit, nashi pears, and peaches is becoming mature enough to provide local fruit to the community.
They also keep bees and make skin care products from their wax. As their website says 'we eat what you eat', which highlights their original desire to feed themselves coupled with their drive to serve their community and provide access to good quality produce for all.
Being a community, we support each other : )
© The Nimbin Organic Food Co-op
 - Grey Facebook Icon


Remember Together
In assemblies leading up to Remembrance Sunday our theme has been 'Remember Together'. Students have been recognising the service, sacrifice, and collaboration of the men and women of Britain, the Commonwealth and Allied nations who fought together 75 years ago in WWII in the lead up to D-day. As part of the assembly Mr. Brown shared the WWII experiences of his own Grandfather who served with the RAF and became a POW. During the 'Last Post' students paid their respect and united to ensure no-one is forgotten and to honour those who have sacrificed themselves to secure & protect our freedom.


text:
(1869–1930) Austrian chemist
Pregl, who was born at Laibach (now Ljubljana in Slovenia), was the son of a bank official. He graduated in medicine from Graz (1893) where he became an assistant in physiological chemistry in 1899. In 1910 he became head of the chemistry department at Innsbruck, remaining there until 1913 when he returned to Graz to become director of the Medico-Chemical Institute.
Pregl began research on bile acids in about 1904 but soon found that he could only obtain tiny amounts. This led him to pioneer techniques of microanalysis. Justus von Liebig had needed about 1 gram of a substance before he could make an accurate analysis; through his new techniques Pregl was capable of working with 2.5 milligrams. This was achieved by the careful scaling down of his analytic equipment and the design of a new balance, which was produced in collaboration with the instrument maker W. Kuhlmann of Hamburg. With this he was capable of weighing 20 grams to an accuracy of 0.001 milligram.
The techniques developed by Pregl are of immense importance in organic chemistry and he was awarded the Nobel Prize for chemistry in 1923 for this work.
Subjects: Science and Mathematics.


text:
Two years of supporting activists in the Sunni-majority country's capital city resulted in projects that championed diversity and countered Covid-related disinformation.
Young Cities began its programming in Pakistan in 2019 through its Youth Civil Activism Network (YouthCAN) initiative. trained 26 activists and supported the launch of three projects that each took on the challenge of promoting diverse narratives and empowering religious minorities in a country where around 91% of its population is Sunni Muslim.
In 2020, the Covid pandemic led to the rise of harmful misinformation and disinformation that spread quickly and unabated, often targeting the country's women and minorities especially. Young Cities adapted its programme to be delivered entirely remotely, and supported four teams of activists to develop a single campaign that addressed different forms of this disinformation.


text:
Did you know 413,000 or 14 percent of Kansans suffer from food insecurity? The issue affects communities across the state, and there's no magic bullet.
The American Farm Bureau wants to be part of the solution and parents, teachers and students can help. Through its Foundation for Agriculture students can tackle food insecurity with the Purple Plow Challenge.
What Is Food Insecurity?
Many children and adults wonder where their next meal is coming from, whether they will have enough food to eat throughout the week, and how to deal with hunger on a regular basis. That is food insecurity. And, it can affect anyone. In fact, many people are surprised to learn that neighbors or friends face food insecurity.
What Is the Purple Plow Challenge?
The Purple Plow Challenge is a program that tasks students with becoming aware of food insecurity issues and championing solutions in their communities. How? By creating and maintaining an edible plant garden. With spring just around the corner, this is a great time to introduce kids to gardening and help them get planting!
The gardens created during the Purple Plow Challenge could serve as prototypes for community gardens in the future designed to help combat food insecurity.
How Does It Work?
Students in grades 5-8 can enter to participate in the challenge, which runs runs through May 1, 2018. BONUS: It's a fun and simple way to get involved with your community and teach students about agriculture, STEM and giving back.
How Do I Start?
Before starting the challenge, sit down with teachers and administrators to set out a plan of action for the classroom, who may be willing to donate supplies and how to teach students about food insecurity.
For the challenge, students must complete an assessment of needs related to food and hunger in their community and then develop a growing space for edible plants. Here are some ideas to help you in your own challenge:
- Identify the problem in your community and describe what the solution may be. For this challenge, the solution may be one of the student's prototypes!
- Set goals for the project so the students know what to aim for when participating in the challenge. Let the students brainstorm all the ways they can fight food insecurity, what design they will use and all the materials needed.
- Build the prototype! This is the most fun part where students (and parents and teachers) get to see their designs come to life. Have them collect data like how long each plant takes to grow, what each plant produces and how much the materials cost.
- Discuss what this prototype could do on a large scale. How many people could they feed? Talk about the results and compare to the goals. Find the areas for improvement and make the changes.
- Finally, share all the ideas, designs, data and conclusions! Look for opportunities in the community to share the student's work and give them the opportunity to share it.
Benefits of Participating
Students will not only learn about the science of growing plants and the engineering of designing the perfect growing space, but they will also learn about food insecurity, population growth and access to resources.
This project has a far-reaching impact from students to parents to members of the community. Try a project that goes beyond the classroom to have a positive influence on those involved.
And finally, you might be able to win a prize for your local school! Enter the students' reflections and presentation or social media post to win one of eight $500 grants from the American Farm Bureau Foundation for Ag in the Classroom. The top three teams will win a 3D printer and Visa gift card to buy supplies for the next challenge.
Ready to start? Visit purpleplow.org for more information.
From the Purple Plow website:
- The Purple Plow encourages students to research scenarios related to food, hunger and sustainability and build their own prototypes to solve the defined problem. Resources provided for facilitators, students and volunteers are written by teachers, aligned to national learning standards and reviewed by industry experts.
- The Purple Plow is a great fit for individuals, groups, and 5th through 8th grade classes. It's perfect for maker spaces, after school programs, in-school lessons, 4-H clubs, library learning, scout troops and more!


Difference between Aluminum and Stainless Steel
Updated on February 14, 2018
Both aluminum and stainless steel are hard metals that have a wide range of applications. The metals look similar but they are very different in that one is an alloy while the other is not. They are also different in terms of composition, density, strength etc. Knowing the difference can help you determine which one you need for your project or which kitchen appliance you need to buy. Here are a few differences:
Definitions
Aluminum
Aluminum spoon
Aluminum is a silvery looking metal element that is both light and strong. These properties have led to its wide applications in making certain objects. For example, aluminum is preferred in making car bodies and airplanes.
Stainless Steel
Kitchen Knife Stainless Steel Cutting edge
Stainless steel is a metal alloy consisting of iron and chromium. The amount of chromium combined with iron can vary from 10 percent to 30 percent so as to achieve the desired characteristics of stainless steel. Some other elements such as titanium and nickel may be added to enhance specific qualities of steel.
Comparison Chart
AluminumStainless steel
Is an element but not an alloyAlloy of iron and chromium
Lighter and not very strong compared to steelHeavier and stronger than aluminum
Doesn't give out sparksGives out sparks when subjected to a grinder
CheaperExpensive
Less reactiveMore reactive than aluminum
Cheaper due to simple refining processMore expensive than aluminum because it involves a lengthy refining process
Aluminum vs Stainless Steel
What is the difference between aluminum and stainless steel? The difference between them lies in their composition, how they react to air and their uses.
 - To tell the difference between aluminum and stainless steel, most people subject them to a grinder. When subjected to a grinder, things made from aluminum do not give out sparks. Stainless steel items give out a lot of sparks when grinded (see video below).
 - Aluminum is an element. It is not a combination of two elements like in the case of stainless steel. Stainless steel is an alloy metal consisting of chromium and iron. Stainless steel does not rust or corrode easily like other metals. The amount of chromium used varies from 10 to 30 percent. Chromium is used so as to make the metal anti-corrosive and rust resistant. Chromium reacts with air to form an oxide film which protects the steel. Stainless steel has a variety of applications including those found in home and restaurant kitchens for making appliances such as rice cookers and utensils.
 - Aluminum is a bit weaker as compared to stainless steel, but it's a lot lighter and hence preferred in making aircraft bodies. Stainless steel is very strong and heavy.
 - Aluminum is available cheaply and it does not require much processing. It's also a good conductor of electricity, hence it is used in making power cables. Aluminum does not rust due to the formation of an oxide coating on its surface. Aluminum is preferred in making boilers and other heating vessels since it does not react with the contents, and conducts heat effectively.
 - Stainless steel, on the other hand, is expensive due to the lengthy refining process and alloying. In most cost conscious projects such as construction, aluminum is used instead of stainless steel.
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text:
Inpatient mental health facilities play a crucial role in providing comprehensive care and support to individuals seeking treatment for mental health disorders. Located in the heart of New Jersey, these specialized facilities offer a safe and nurturing environment for individuals who require intensive treatment and monitoring. With a focus on holistic approaches, these state-of-the-art facilities aim to address the unique needs of each patient, promoting their mental wellness and overall well-being. Staffed by a team of experienced psychiatrists, psychologists, nurses, and therapists, the inpatient mental health facility in New Jersey strives to deliver evidence-based treatments, including therapy sessions, medication management, and various therapeutic activities. The compassionate and dedicated professionals work closely with patients to develop personalized treatment plans that cater to their specific symptoms, while also addressing any underlying factors contributing to their mental health concerns. By combining specialized care, a supportive environment, and an emphasis on long-term recovery, these facilities are dedicated to empowering individuals on their journey towards mental health stability and improved quality of life.
- Inpatient mental health facilities in New Jersey provide comprehensive care for individuals experiencing severe mental health conditions.
- These facilities offer 24/7 supervised treatment and support for individuals who require a higher level of care than outpatient services can provide.
- Inpatient mental health facilities in New Jersey typically have a multidisciplinary team of mental health professionals, including psychiatrists, psychologists, nurses, and social workers, who work together to create personalized treatment plans.
- Inpatient care can include a range of therapeutic interventions such as individual and group therapy, medication management, holistic approaches, and activities designed to promote healing and recovery.
- What is the process for admitting someone to a mental hospital in New Jersey?
- In New Jersey, what is the maximum duration for which a mental hospital can detain an individual?
- What is the number of mental hospitals in New Jersey?
- Exploring the Benefits of Inpatient Mental Health Facilities in New Jersey: A Comprehensive Analysis
- New Jersey's Cutting-Edge Inpatient Mental Health Facility: Revolutionizing Mental Healthcare within the State
- Comprehensive and specialized care: Inpatient mental health facilities in New Jersey provide comprehensive and specialized care for individuals with mental health issues. These facilities have trained professionals and psychiatrists available around the clock to provide personalized treatment and support.
- Safety and stability: Inpatient mental health facilities offer a controlled and secure environment. This ensures the safety of patients, especially those who might be a danger to themselves or others. The structured setting also promotes stability and encourages individuals to focus solely on their mental health recovery.
- Multidisciplinary approach: Inpatient facilities utilize a multidisciplinary approach to mental health care. This means that professionals from various fields, such as psychiatrists, psychologists, nurses, and therapists, work together to develop individualized treatment plans. This collaborative approach ensures a holistic and comprehensive approach to addressing mental health issues.
- Intensive therapy and support: Inpatient facilities in New Jersey provide intensive therapy and support, offering a wide range of evidence-based treatments. These may include individual therapy, group therapy, family therapy, psychoeducation, and medication management. The availability of diverse therapeutic options within the facility enhances the chances of successful recovery.
- Limited privacy: Inpatient mental health facilities in New Jersey often have shared living spaces, with individuals having limited privacy. This lack of personal space can be distressing for some patients, limiting their sense of autonomy and comfort.
- Restricted outside interaction: Patients in inpatient mental health facilities often have limited or no contact with the outside world, including family and friends. This isolation can contribute to feelings of loneliness and hinder the patient's emotional healing process.
- High cost of care: Inpatient mental health facilities in New Jersey can be quite expensive, making it difficult for individuals with limited financial resources to access essential mental health services. The high cost of care may restrict the availability and affordability of these facilities for individuals in need.
- Stigma and social implications: Seeking treatment in an inpatient mental health facility can unfortunately still carry negative social implications and stigma. This can affect both the patient and their families, as they may face judgment, discrimination, or misunderstandings from friends, colleagues, or society, potentially hindering their overall recovery and mental well-being.
What is the process for admitting someone to a mental hospital in New Jersey?
The process for admitting someone to a mental hospital in New Jersey involves several requirements. Firstly, the individual must be mentally ill. Secondly, their mental illness must pose a threat to themselves, others, or property. These criteria are defined specifically by NJSA §§ 30:4-27.2(h) and -27.2(i). Lastly, it is necessary to determine that appropriate facilities or services are not available for the treatment of the individual. This ensures that involuntary commitment is utilized only when necessary and under specific circumstances.
In New Jersey, the process of admitting someone to a mental hospital requires the individual to meet certain criteria. Specifically, they must be mentally ill and their mental illness must pose a threat to themselves, others, or property. Additionally, it must be established that suitable facilities or services for their treatment are not available, ensuring that involuntary commitment is only used when absolutely necessary and under specific circumstances.
In New Jersey, what is the maximum duration for which a mental hospital can detain an individual?
In New Jersey, the maximum duration for which a mental hospital can detain an individual is 72 hours. This time period starts from the moment a psychiatrist screens them or issues a screening certificate. However, if the hospital or emergency department obtains a temporary court order, they can extend the detention for an additional 72 hours. This restriction ensures that individuals receiving psychiatric care have appropriate rights and protections while seeking treatment in the state of New Jersey.
In New Jersey, individuals seeking psychiatric care can only be detained in a mental hospital for a maximum of 72 hours. This duration begins once a psychiatrist screens them or issues a screening certificate. However, if a temporary court order is obtained by the hospital or emergency department, the detention can be extended for an additional 72 hours. These measures guarantee that individuals in need of psychiatric treatment have their rights and protections upheld in New Jersey.
What is the number of mental hospitals in New Jersey?
New Jersey is home to a dedicated system of four inpatient psychiatric hospitals operated by the Department of Health. With a strong emphasis on patient-focused care and a commitment to wellness and recovery, these facilities strive to provide high-quality mental healthcare to those in need. These hospitals play a vital role in addressing the mental health needs of the state, offering a specialized and comprehensive approach to treatment and support.
In the state of New Jersey, there exists a well-established network of four psychiatric hospitals under the Department of Health. These facilities prioritize patient-centered care and aim to promote wellness and recovery by delivering top-notch mental healthcare services. They serve a crucial role in addressing the mental health needs of the state through their specialized and comprehensive treatment approach.
Exploring the Benefits of Inpatient Mental Health Facilities in New Jersey: A Comprehensive Analysis
Inpatient mental health facilities in New Jersey offer a comprehensive approach to treat individuals suffering from mental illnesses. These facilities provide a safe and controlled environment where patients can receive round-the-clock care from a multidisciplinary team of experts. In addition to providing medications and therapy sessions, inpatient facilities also offer various therapeutic activities and support groups, fostering an inclusive community and promoting social interaction. Furthermore, these facilities provide a structured daily routine, ensuring patients receive the necessary structure and stability to improve their mental health. Overall, inpatient mental health facilities in New Jersey play a crucial role in promoting recovery, providing a wide range of benefits for individuals in need of intensive care.
In New Jersey, inpatient mental health facilities offer a comprehensive approach to treating mental illnesses. They provide a safe environment with round-the-clock care from experts, medications, therapy sessions, therapeutic activities, and support groups. A structured daily routine ensures the necessary structure and stability for patients to improve their mental health and promote recovery.
New Jersey's Cutting-Edge Inpatient Mental Health Facility: Revolutionizing Mental Healthcare within the State
New Jersey's state-of-the-art inpatient mental health facility is spearheading a revolution in the way mental healthcare is provided within the state. With a cutting-edge approach, this facility aims to transform the traditional model of care by implementing innovative therapies and advanced technologies. By combining compassionate and personalized treatment plans with evidence-based practices, patients can expect enhanced outcomes and an improved quality of life. This forward-thinking facility is dedicated to combating the stigma surrounding mental health while providing the highest standard of care for individuals in need.
In New Jersey, a state-of-the-art mental health facility is revolutionizing the way care is provided. Through cutting-edge therapies and advanced technologies, this facility is transforming the traditional model by offering personalized treatment plans and evidence-based practices, ultimately improving patient outcomes and their quality of life. Additionally, it aims to combat the stigma surrounding mental health while providing top-notch care to those in need.
The establishment of inpatient mental health facilities in New Jersey has significantly contributed to the improvement of mental healthcare services in the state. These facilities offer a safe and secure environment for individuals struggling with various mental health disorders to receive the necessary treatment and support. The dedicated team of professionals, including psychiatrists, psychologists, and therapists, provide personalized care and evidence-based therapies tailored to each patient's needs. Additionally, the integration of holistic approaches, such as art therapy, yoga, and mindfulness, further enhances the healing process. The availability of inpatient mental health facilities not only helps decongest overcrowded emergency rooms but also reduces the burden on outpatient services by providing more intensive and comprehensive care. By investing in the expansion and improvement of these facilities, New Jersey continues to prioritize the mental well-being of its residents, fostering a healthier and more resilient community.


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Chemical probing of histidine residues using specific modifiers, iodoacetic acid (IAA) and diethylpyrocarbonate (DEP) resulted in the inactivation of phytase (phy A). The kinetic theory of the substrate reaction during the modification of enzyme activity was applied to a study of the kinetics of the course of inactivation of phytase by IAA and DEP. The results suggested that histidine residues are involved in the active site of the enzyme. They also indicated that inactivation of the enzyme by IAA was via a complexing type inhibition, while the inhibition by DEP reaction involved a conformational change step before inactivation. The dissociation constant of the enzyme-inhibitor complex of IAA, the constant of the conformational change of DEP and the microscopic rate constants of two inhibitors were obtained.
Keywords: Phytase, inactivation, kinetics, iodoacetic acid, diethylpyrocarbonate
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CMES Dr. Khaldoon A Mourad proposes a possible Water Compact for a functioning water governance system in Somalia
Therefore, in cooperation with UNDP and the Ministry of Energy and water resources and the Office of the Prime Minister, a national technical workshop was held in Mogadishu in March 2020.
Four thematic areas
All involved stakeholders agreed on developing a water compact covering four thematic areas:
- water governance
- water use and services
- water resilience
- integrated water resources management


text: Purpose: Arterial spin labeling (ASL) techniques have been implemented across a diverse range of clinical and experimental applications. This review aims to evaluate the current feasibility of ASL in clinical neuroradiology based on recent improvements to ASL sequences and highlight areas for potential clinical applications. Methods and Materials: In December 2014, a literature search was conducted on PubMed Central, EMBASE, and Scopus using the search terms: ?arterial spin labeling, neuroradiology,? for studies published between 2009 and 2014 (inclusive). Of 483 studies matching the inclusion criteria, the number of studies using continuous, pseudocontinuous, pulsed, and velocity-selective ASL sequences was 42, 209, 226, and 3, respectively. Studies were classified based on several common clinical applications according to the type of ASL sequence used. Studies using pulsed ASL and pseudo-continuous ASL were grouped based on common sequences. Results: The number of clinical studies was 264. Numerous studies applied ASL to stroke management (43 studies), drug testing (21 studies), neurodegenerative diseases (40 studies), and psychiatric disorders (26 studies). Conclusions: This review discusses several factors hindering the implementation of clinical ASL and ASL-related radiofrequency safety issues encountered in clinical practice. However, a limited number of search terms were used. Further development of robust sequences with multislice imaging capabilities and reduced radiofrequency energy deposition will hopefully improve the clinical acceptance of ASL.


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by Charles R. Gamble and James G. Lewis
This report is available as a pdf below
A method is presented for estimating the depth of the loo-year flood in four hydrologic areas in Tennessee. Depths at 151 gaging stations on streams that were not significantly affected by man made changes were related to basin characteristics by multiple regression techniques. Equations derived from the analysis can be used to estimate the depth of the loo-year flood if the size of the drainage basin is known.
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|U.S. Department of the Interior, U.S. Geological Survey
Page Contact Information: Contact USGS
Last modified: Thursday, September 01 2005, 02:07:02 PM


How many standard drinks can you have before driving if you are under 20 years old? How many standard drinks can you have before driving if you are under 20 years old?
 - A. One
 - B. Two
 - C. Three
 - D. None
 The correct answer is D
 The legal limit is 0 milligrams per 100 millilitres of blood. A drink consumed before driving will almost certainly put you over this limit. So you must not drink just before driving if you are under 20 years old as there is a zero alcohol limit.
How to calculate if you are over the legal drink driving limit
You cannot calculate your blood alcohol level because it depends on a large number of variables such as your age, weight, gender, general health and fitness, the amount of alcohol you've drunk, the type of alcohol you've drunk, and whether you've eaten (how much and how recently).
A small drink could put you over the limit. If you're stopped and your breath alcohol reading is between 30-150mcg per litre of breath you could be fined and given 50 demerit points. That means you are half way to being disqualified. You will receive a notice from NZTA that you have accumulated 50 demerit points and if this total exceeds 100 within a 2-year period you will be disqualified.
If you are caught with more than 150mcg of alcohol per litre of blood then you could be fined up to $2250 and sent to prison for up to 3 months and be disqualified from driving for at least 3 months, plus you'll still get 50 demerit points. If you are disqualified you may be able to apply for a special licence with zero alcohol or an alcohol interlock requirement.
If you blow over the limit you may be asked to provide an evidential blood or breath test. It is an offence to refuse consent.
Younger drivers tend to have less ability to cope with alcohol intake. Add to that their lack of experience and you can understand why the risk of having an accident is increased dramatically.
Read more about alcohol limits, including fines and penalties, in this article.


Woman wearing blazer
Possibly a development of the nautical reefer jacket, a blazer is a loose-fitting and lightweight flannel sports jacket. Coming in both double-or single-breasted styles, although most are double-breasted, a blazer is generally tailored in either plain navy or black, has brass buttons, two side vents, is thigh length and in many cases has a breast-pocket badge. A well-constructed blazer can make even a pair of jeans appear smart. The blazer is generally considered to be a vital component of the "preppy" or "British look."
History of the Blazer
The familiar navy blazer traces its origins back to the captain of the frigate HMS Blazer, who had short double-breasted jackets cut in navy blue serge for his scruffy-looking crew when Queen Victoria visited his ship in 1837. The crew's "blazers" with their shining brass Royal Navy buttons impressed the Queen and soon became part of their dress uniform.
It is believed that the heavier double-breasted reefer jacket was the inspiration for the captain's original blazer design. What is less clear is how and why the naval blazer came to be worn by civilians. One likely explantion, and probably why so many owners of yachts and other sailing vessels wear blazers, is that many people who had no obvious association with the sea or indeed the navy could still have blazer jackets made originally for maritime experiences. With traditional outfitters such as Gieves and Hawkes, on London's Savile Row, cutting blazers for Royal Naval officers it is likely that many civilians would get their own tailors to copy a version for them. If buttons with emblems were not used then simple flat brass buttons were, although it would then become difficult to distinguish the blazer from the other sports jackets.
Divorced from any military background, the single-breasted blazer was the favored style of club jacket worn by rowing clubs in the nineteenth century. These would be made up in college, school, or club colors to be worn at special outdoor sporting events, such as the Henley Royal Regatta. Crests and other insignia were often embroidered in heavy gold thread on the left breast pocket, and the buttons were similar to those used by the navy. Men who were not in a sporting club might still wear a blazer but, as with the naval-inspired version, more likely using enamel buttons instead of brass.
Worn by many Europeans for both work and leisure and popularized by Brooks Brothers for the American market in the early twentieth century (and later in bright colors, such as bottle green or yellow, for golf attire), the authentic British blazer (and its imitations) have held a minor but consistent place in the male wardrobe for decades. The blazer's most recent revival was as essential executive dress in the 1980s, often worn with open shirt and cravat. Its popularity is limited somewhat by its reputation as being too formal for the young, and too stuffy for the "casual dress" office.
See also Jacket; Sports Jacket.
Hardy Amies. A,B,C of Men's Fashion. London: Cahill and Company Ltd., 1964.
Byrde, Penelope. The Male Image:-Men's Fashion in England _PHONE_. London: B. T. Batsford Ltd., 1979.
De Marley, Diana. Fashion for Men: An Illustrated History. London: B. T. Batsford Ltd., 1985.
Keers, Paul. A Gentleman's Wardrobe. London: Weidenfeld and Nicolson, 1987.
Wilkins, Christobel. The Story of Occupational Costume. Poole: Blandford Press, 1982.


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Old Major (a pig) Timeline and Summary
- Old Major has a dream and calls a conference to discuss it.
- He predicts his own death and blames man for their problems.
- He proposes a rebellion and presents "Beasts of England."
- He sets forth several rules the animals must follow so as not to ever resemble man.
- He proposes, as a fundamental principle, that all animals are equal.
- Old Major dies in his sleep.


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|Photo by Coke Smith (Coke & Som Smith Photography)|
reed parrotbill (en); bico-de-papagaio-do-Yangtzé (pt); paradoxornis du Yangtsé (fr); picoloro del Yangtsé (es); Jangtsepapageimeise (de)
This Asian species occurs in two separate areas, one in north-eastern China, and across the border into Mongolia and Russia, and another in south-eastern China, along the Yangtze river.
These birds are 20-24 cm long and weigh 17-28 g.
These birds are found in reed beds, in freshwater lakes, rivers and streams. They occur from sea level up to an altitude of 800 m.
Reed parrotbills mostly eat insects, but also seeds.
These birds nest in a cup-shaped nest, made of leaves and grasses, attached to the stalk of a reed. There the female lays 3-5 eggs, which are incubated for 12-13 days. The chicks fledge 12 days after hatching.
IUCN status - NT (Near-Threatened)
This species has a restricted breeding range and is described as locally common, but totally dependent on reedbeds. The reed parrotbill is likely to be declining throughout its range as a result of human encroachment, development and habitat degradation within reed bed habitats due to reed harvesting.


Next:, Previous:, Up: Simple projects [Contents]
7.3.3 ede-linux
The ede-linux project will automatically identify a Linux Kernel source tree, and enable EDE project mode for it.
It pre-populates the C Preprocessor symbol map for reasonable parsing, and has an optimized include file identification function.
Through the variables project-linux-build-directory-default and project-linux-architecture-default, you can set the build directory and its architecture, respectively. The default is to assume that the build happens in the source directory and to auto-detect the architecture; if the auto-detection fails, you will be asked.


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Modelling Conductive Heatflow Through A Heat-shielding Tile On A Spaceshuttle During Reentry
Tutorhunt asked me to upload an article but I'm not sure the formatting on this transfers well to tutorhunt, if you're actually interested I'll happily email it to you, descri ption in the abstract.
Date : 9/26/2016
This report investigates different numerical methods for solving PDEs which are used to model the temperature change and inner surface temperature through a heat shielding tile, which is on a space shuttle re entering earths atmosphere. Matlab is used for forward differencing, backwards differencing, the Dufort Frankel Model, and Crank Nicolson Method. The stability of these methods is discussed and the efficiency of the most stable method is investigated. It was found that the Crank Nicolson is the most stable and accurate method. It gave the ideal thickness to be between 60 and 80mm, depending on it's position the space shuttle.
Numerical modelling of PDE's is extremely important in designing real world systems where it is not always possible to measure there characteristics of a system. This could be due to it being extremely expensive, too large, or simply not feasible. In this report a space shuttle's heat shielding tile is modelled as it is heated whilst re entering earths orbit. During re entry a space shuttle experiences extreme heating due to friction between the air and the shuttles body. The shuttle hits the earths atmosphere at hyper-sonic speeds 100km from the surface. The friction from the air causes it to heat to over 1000 °C causing almost anything to burn up, the pressure from this causes objects with low compressive strength to explode. (1) For the shuttle to avoid burning up it's surface inside the tiles must not exceed 175°C (2).
⦁ The shuttle will always experience the same heating
The shuttles were reusable, and the heating effects from different ambient conditions, different entry speeds and angles was varied each time
⦁ The tile's thickness is uniform
The tiles are assumed to have a constant cross section, and are not damaged.
⦁ The tile's thermal properties are consistent.
The tiles were made batches, it's assumed that each batch had the same thermal properties.
⦁ The tiles don't degrade
The tiles had a long life time, it's assumed that their properties didn't change.
⦁ The tiles are only heated from one side
If there is any heating between the tiles it could cause them to behave differently. It's assumed that they're only heated from the external face.
Four different methods of solving PDEs are used to solve the Fourier Equation which describes the heat flow through objects:Also required is the thermal diffusivity:
Forwards Differencing has first order accuracy in time, and second order accuracy in space due to truncation of the Taylor Series. It's unstable when it's timestep. This is very limiting and makes it one of the lesser used methods for solving PDEs.
The Dufort Frankel model is an unconditionally stable version of the leap frog method, it is accurate to the second order in both time and space, however at large timesteps experiences oscillatory behaviour.
The Backwards Differencing method approximates at the new timestep, calculating by looking back in time, this is the reverse of Forward Differencing.
This is more stable, it has first order accuracy in time and second order accuracy in space.
The Crank Nicholson method uses approximations of Forward and Backward Differencing methods.
This method has second order accuracy in time and space, and is stable at large timesteps.
The stability of the methods is found by increasing the time step and plotting the inner temperatures. The more consistent the temperatures are the more stable the method, when the temperature deviates suddenly it will be unstable at all larger step sizes.
Fig.1 Stability graph, the Crank Nicholson method is most stable, and Forward dDifferencing is least stable.
The results agree with the theory, with Forward Differencing quickly becoming unstable, the Dufort Frankel Model experiencing oscillatory behaviour at large time steps, Backwards Differencing and Crank Nicolson are stable, with Crank Nicolson having second order accuracy.
The temperature data from the shuttle is found by converting a graph from NASA into a data vector on matlab. Tile 597 is used throughout this report. (3)
Fig.3 Temperature with time through the narrowest part of the tile.
This graph shows how the temperature inside the tile varies with time. The tile insulates the shuttle, as the inner surface is cooler than the outside. There is a thermal lag between the outside and inside, so the inner edge is still getting hotter when the outside is starting to cool down. This was also modelled in 3 dimensions, but the inner surface temperatures were identical. (appendix 1)
The temperature on the inside of the tile is found for different tile thicknesses, this should not exceed 175°C during re entry. The exact thickness required is found by using the shooting method to be 57mm. The bare minimum has no margin for error, so the inner surface temperature is found for a range of thicknesses.
Fig.4 Temperature for varying tile thicknesses, the thick purple line is the trendline from 100 thicknesses over the same range.
This shows an exponential change in maximum temperature for decreasing tile thickness. The greater the thickness the longer the delay before the maximum temperature is reached.
To illustrate how increasing the number of steps can cause a decrease in efficiency, the time to solve the problem was measured for a several numbers of time and spatial steps.
Fig.5 Graph of number of time and spatial steps against the time it takes to solve the problem.
Increasing either step size does not drastically impact the time taken, increasing both together can cause the program to become inefficient and take much longer requiring a lot more computing power. The final solution uses only 500 spatial and time steps, using more is unnecessary, but in larger models it may be unavoidable.
For the final result 500 time and spatial steps were used, this is fast enough, and gives precise results. Using fewer steps works, but the difference in the time it takes is negligible.
The solution was modelled using both one and two dimensions, and it was found that although there's a very small difference in some circumstances, normally there is no difference. This is because theat flows most quickly through the shortest path, so adding longer ones doesn't change anything. However modelling a defective tile would need two or three dimensions. Real world conditions perhaps create the biggest innaccuracies, when space shuttles re entering earths will not experience the same heating effect every time. On a colder day air is denser, and there is more heating, whereas on a hot day the shuttle will fall faster through the less dense air, which would change the heating on the tile.
Numerical modelling is clearly a very good way of determining how something will behave in real world conditions. But it is very hard to base a design off modelling alone. Real world measurements are needed to validate the results. Of course in the case of a space shuttle this is very hard to do, and the 57mm tile thickness found by the shooting method would be a good guide. The designers would then have to consider how much safety factor to build into the shuttle. Adding extra thickness would make it a safer, as any damage it more likely to be on the surface and not affect the the rest of the shuttle. The real shuttle used thicknesses ranging from 25 to 127mm, so clearly there is not one correct thickness. (4) As real world validation is not available, modelling is the next best thing.
⦁ Plottemp.m works automatically, and allows the user to select the temperature graph, first by cropping around the desired graph, then on the axes.
⦁ The program Thickness.m plots the temperature on the inside of the tile for a range of tile thicknesses, as well as a line through the maximum temperatures.
⦁ Timer.m creates a graph of the time taken by the program for varying number of steps. The data is saved at the end because it takes such a long time.
⦁ GUI2.m is a gui which runs plottemp and shuttle. It allows the user to change the variables and to select the temperature graph they want to use.
⦁ Shooting.m runs the shooting method to find the correct tile thickness for a desired inner surface maximum temperature.
⦁ Shuttle2D is exactly the same as shuttle, but instead uses two dimensions and plots the results changing in time. (6)
This resource was uploaded by: Sean