Skip Headers
Oracle® Fusion Middleware User's Guide for Oracle Imaging and Process Management
11g Release 1 (11.1.1)
Part Number E12783-02
Go to Documentation Home
Go to Book List
Book List
Go to Table of Contents
Go to Index
Go to Master Index
Master Index
Go to Feedback page
Contact Us
Go to previous page
Go to current chapter
Go to next page
View PDF
2 Understanding Applications and Metadata
This section explains what an application is and provides an overview of how metadata is defined and subsequently associated with documents managed by Oracle I/PM. It contains the following topics:
2.1 Understanding Applications
Applications are the core of Oracle I/PM. Consider an application as a type of management container for documents. You select an application to use when uploading documents to Oracle I/PM and that application determines what information, or metadata, is associated with the uploaded document. The associated metadata may be visible to you and require you to input information into a form, such as entering an invoice number for the document, or the metadata may be invisible to you and used by the Oracle I/PM system, such as the security permissions required to retrieve the document. Each application has a different set of metadata, called a definition, which is determined by the person creating the application. An application definition is used to:
2.2 Understanding Metadata
Metadata is the set of information associated with a document at the time the document is uploaded to Oracle I/PM and is specified by the application used to upload the document. Metadata is different for each type of document because each type of document is uploaded using a different application. The metadata defined in each application is different because it is determined by the business need and agreed upon by the people responsible for the business process. Metadata can be visible to you, such as the information you enter when uploading or searching for a document, or it may be invisible to you and used by the Oracle I/PM system, such as security settings allowing access to the document, or a workflow that must be initiated when the document is uploaded.
2.2.1 Visible Metadata
Metadata can include invoice numbers, dates, company names, and any other information required by a business process. For example, invoice numbers may be tracked for invoices, but not for vendor contracts, job applications, or loan applications. The person creating the application determines the metadata fields used throughout the Oracle I/PM interface. This visible metadata is displayed on forms used when uploading documents, or on search forms used for retrieving documents. For example, the Accounting and Shipping departments for Corporate Car Rental may agree that lease metadata should include the following information which will allow both departments to access the required information to complete their jobs:
 - Lease number
 - Car Delivery Date
 - Lease Expiration Date
 - Amount Due
You would fill in values for these fields on a form used to upload lease documents, and the metadata can be indexed and used to search for and retrieve documents from the repository.
2.2.2 System Metadata
An application definition also includes information that you cannot see when uploading or searching for a document, but is necessary for the document to move through a business process. Such metadata includes permissions to retrieve and view a document, information regarding the document storage and archiving, and whether or not the document must go through a workflow. This metadata is not something you control, but is defined in the application by the person creating the application based on the needs of the business process for which the application is being used.
2.3 Associating Metadata with Documents
Each time a document is uploaded to Oracle I/PM, it is put into an application that has been designed for that type of document. If uploaded through a scanning station or other automated process, the metadata values are specified and populated during the upload process. If you are uploading the document manually, you choose the application to use and the application displays a form listing the metadata for which you can specify values. The values you specify in the form are the values for the metadata associated with the document as it is uploaded. Whether the metadata values are specified automatically during an automated upload or by you when you upload the document manually, the values are indexed and can then be used to search for and retrieve documents.
For example, when uploading an invoice, you might select an application named Invoices, which displays a form that includes a field for Invoice Number. When you enter the invoice number into the field and upload the document, that value gets indexed. To retrieve the document, you can select Invoices under your Searches panel and enter the value into the Invoice Number field in the search form. Because the value was indexed when the document was uploaded, Oracle I/PM finds it and displays it in the viewer.
2.4 Searching Document Metadata
The metadata associated with documents when they are uploaded can be used as criteria to search for and retrieve documents from Oracle I/PM. All fields are searchable, but not all fields may be made available to you on a search form.
The person creating a search creates it in a way similar to creating an application. The person creating the search determines what metadata fields you see in a search form. Each search is displayed in the Searches panel of the Navigator pane. Clicking a search link displays a form requesting search parameter metadata associated with the type of documents you are searching for. Because an application determines the metadata to be used as search criteria, most search options in Oracle I/PM have a direct correlation with the application in which a document resides. For example, if there is an application named "Leases" for uploading leases, then there is likely a search named "Current Leases" that displays a search form to enter criteria to find lease documents within a certain date range. However if necessary, a single search form can be created to be used to search across multiple applications.
Depending on how Oracle I/PM is configured, document content (full text) may also be made available for searching. For example, text from a leasing contract may get indexed when the lease is uploaded to Oracle I/PM, enabling you to search for words or phrases from within the lease. Like metadata, searches for the full text of documents is done using a field on the search form when the search is created. If you are uncertain whether your version of Oracle I/PM supports full text searching, ask your system administrator.


^{\pm}}\varphi(\Theta)\) is harmonic in \(C_{n}(\Omega)\), belongs to the class \(C^{2}(C_{n}(\Omega )\backslash\{O\})\) and vanishes on \(S_{n}(\Omega)\), where
$$2\aleph^{\pm}=-n+2\pm\sqrt{(n-2)^{2}+4\lambda}. $$
In the sequel, for the sake of brevity, we shall write χ instead of \(\aleph^{+}-\aleph^{-}\). If \(\Omega={\mathbf{S}}^{n-1}_{+}\), then \(\aleph^{+}=1\), \(\aleph^{-}=1-n\) and \(\varphi(\Theta)=(2n w_{n}^{-1})^{1/2}\cos\theta_{1}\).
Let \(G_{\Omega}(P,Q)\) (\(P=(r,\Theta), Q=(t,\Phi)\in C_{n}(\Omega)\)) be the Green function of \(C_{n}(\Omega)\). Then the ordinary Poisson kernel relative to \(C_{n}(\Omega)\) is defined by
$$\mathcal {PI}_{\Omega}(P,Q)=\frac{1}{c_{n}}\frac{\partial}{\partial n_{Q}}G_{\Omega}(P,Q), $$
where \(Q\in S_{n}(\Omega)\), \(c_{n}= 2\pi\) if \(n=2\) and \(c_{n}= (n-2)w_{n}\) if \(n\geq3\).
The estimate we deal with has a long history which can be traced back to Levin's type boundary behaviors for functions harmonic from below (see, for example, Levin [1], p.209).
Theorem A
Let \(A_{1}\) be a constant, \(u(z)\) (\(|z|=R\)) be harmonic on \(T_{2}\) and continuous on \({\partial T}_{2}\). Suppose that
$$u(z)\leq A_{1}R^{\rho}, \quad z\in T_{2}, R>1, \rho>1 $$
and
$$\bigl\vert u(z)\bigr\vert \leq A_{1}, \quad R\leq1, z\in{ \overline{T}}_{2}. $$
Then
$$u(z)\geq-A_{1}A_{2}\bigl(1+R^{\rho}\bigr) \sin^{-1}\alpha, $$
where \(z=Re^{i\alpha}\in{T}_{2}\) and \(A_{2}\) is a constant independent of \(A_{1}\), R, α and the function \(u(z)\).
Recently, Pan et al. [2] considered Theorem A in the n-dimensional case and obtained the following result.
Theorem B
Let \(A_{3}\) be a constant, \(u(P)\) (\(|P|=R\)) be harmonic on \(T_{n}\) and continuous on \(\overline{T}_{n}\). If
$$ u(P)\leq A_{3}R^{\rho}, \quad P\in T_{n}, R>1, \rho>n-1 $$
(1.1)
and
$$ \bigl\vert u(P)\bigr\vert \leq A_{3}, \quad R\leq1, P\in \overline{T}_{n}, $$
(1.2)
then
$$u(P)\geq-A_{3}A_{4}\bigl(1+R^{\rho}\bigr) \cos^{1-n}\theta_{1}, $$
where \(P\in T_{n}\) and \(A_{4}\) is a constant independent of \(A_{3}\), R, \(\theta_{1}\) and the function \(u(P)\).
Now we have the following.
Theorem 1
Let K be a constant, \(u(P)\) (\(P=(R,\Theta)\)) be harmonic on \(C_{n}(\Omega)\) and continuous on ̅. If
$$ u(P)\leq KR^{\rho(R)}, \quad P=(R,\Theta)\in C_{n}\bigl( \Omega;(1,\infty)\bigr), \rho(R)>\aleph^{+} $$
(1.3)
and
$$ u(P)\geq-K, \quad R\leq1, P=(R,\Theta) \in \overline{C_{n}(\Omega)}, $$
(1.4)
then
$$u(P)\geq-KM\bigl(1+\rho(R)R^{\rho(R)}\bigr)\varphi^{1-n}\theta, $$
where \(P\in C_{n}(\Omega)\), \(\rho(R)\) is nondecreasing in \([1,+\infty)\) and M is a constant independent of K, R, \(\varphi(\theta)\) and the function \(u(P)\).
By taking \(\rho(R)\equiv\rho\), we obtain the following corollary, which generalizes Theorem B to the conical case.
Corollary
Let K be a constant, \(u(P)\) (\(P=(R,\Theta)\)) be harmonic on \(C_{n}(\Omega)\) and continuous on ̅. If
$$u(P)\leq KR^{\rho}, \quad P=(R,\Theta)\in C_{n}\bigl( \Omega;(1,\infty)\bigr), \rho>\aleph^{+} $$
and
$$u(P)\geq-K, \quad R\leq1, P=(R,\Theta) \in \overline{C_{n}(\Omega)}, $$
then
$$u(P)\geq-KM\bigl(1+R^{\rho}\bigr)\varphi^{1-n}\theta, $$
where \(P\in C_{n}(\Omega)\), M is a constant independent of K, R, \(\varphi(\theta)\) and the function \(u(P)\).
Remark
(see [2])
From corollary, we know that conditions (1.1) and (1.2) may be replaced with weaker conditions
$$u(P)\leq A_{3}R^{\rho}, \quad P\in T_{n}, R>1, \rho>1 $$
and
$$u(P)\geq-A_{3}, \quad R\leq1, P\in\overline{T}_{n}, $$
respectively.
2 Lemma
Throughout this paper, let M denote various constants independent of the variables in question, which may be different from line to line.
Lemma 1
(see [35])
$$ \mathcal{PI}_{\Omega}(P,Q)\leq M r^{\aleph^{-}}t^{\aleph^{+}-1}\varphi( \Theta)\frac{\partial\varphi( \Phi)}{\partial n_{\Phi}} $$
(2.1)
for any \(P=(r,\Theta)\in


text:
updated Jan 27, 2009 12:07 pm | 4,375 views
The term "account harvesting" refers to the attacking technique or activities of grabbing legitimate user IDs and even passwords to gain access to target systems for illegal or malicious purposes.
The term account harvesting refers to the attacking technique or activities of grabbing legitimate user IDs and even passwords to gain access to target systems for illegal or malicious purposes.
Javvin Technologies
Account Harvesting is the process of collecting all the legitimate account names on a system. Sniffing software is often used to harvest accounts.
Account Harvesting is often used to refer to computer spammers, individuals who try to sell or seduce others through email advertising or solicitation. Account harvesting involves using computer programs to search areas on the Internet in order to gather lists of email addresses from a number of sources, including chat rooms, domain names, instant message users, message boards, news groups, online directories for Web pages, Web pages, and other online destinations.
Account harvesting is a type of authentication attacks. It usually works out for applications that respond differently to a login request with an incorrect user ID and/or an incorrect password. Different reponses from the server to valid versus invalid authentication requests may allow the valid accounts on the system to be guessed and harvested.
It is noteworthy that different login error messages may sometimes be intentional - simply to let legal users know immediately what login information is wrong. However, the difference in the application response provides the attacker with significant hints to the correct account information.
Difference in the application response may be classified into the following:
COMMON DEFENSIVE MEASURES
Here are some common defensive measures against account harvesting:
Ensure that consistent error messages are utilized for account-relevant requests with multiple outcomes (e.g., incorrect user id and/or incorrect password); To defend against the enumeration of valid accounts, use generic messages like "Login Invalid".
Ensure that the accompanying information items listed below are consistent for different account-relevant error messages:
Ensure that error messages are returned in approximately the same time. It is also an option to set a random wait time for all responses to conceal the timing details from the attacker.
Accounts can be locked out temporarily when account harvesting is detected.
The attack can be considerably slowed down by the required additional information to access the secret question for a valid account. The additional information can be the birthdate of the user's mother, the combinition of the user's and his wife's birth years, last six of the user's SSN or some numbers on a credit card. without providing the additional information, the access to the selected secret question of an account should not be allowed.
Monitor and analyze login logs via application intelligence for suspicious login patterns. Such patterns may cover a series of login failures across a list of accounts, a series of login failures across a single account, and a series of login failures for invalid accounts. That will help to detect account harvesting attempts.
Most of account cracking tools, key-stroke loggers, packet sniffer tools, packet capture utilities, rootkits and Trojan login programs can be leveraged for account harvesting.
Related White Papers and Webcasts
Disclaimer: IT Wiki is a service that allows content to be created and edited by anyone in the community. Content posted to this site is not reviewed for correctness and is not supported by Toolbox.com or any of its partners. If you feel a wiki article is inappropriate, you can either correct it by clicking "Edit" above or click here to notify Toolbox.com.

source: HuggingFaceFW/fineweb-edu


Take the 2-minute tour ×
What is the difference between the term cipher (a name like RIJNDAEL) and mode of operation (like ECB)?
Aren't these both terms for the encryption/decryption technique?
share|improve this question
No, Rijndael is a cryptographic primitive that you can do things with, a mode of operation is the method of using it. It is like saying that your block cipher is SUGAR, and the mode of operation is COOKIES or M&MS – Richie Frame Oct 18 '13 at 7:00
3 Answers 3
A mode of operation is an explicit method by which we use a block cipher (eg AES) to do more than just encrypt one block of data. For example, it may allow us to encrypt multiple blocks of data (eg ECB,CBC etc), provide us with some authenticated encryption (eg GCM) or a method for encrypting disc storage (eg XTS).
Rijndael,DES etc are block ciphers. That means they provide a method for encrypting a fixed amount of data (in the case of AES, they encrypt blocks on 128 bits).
In practice, the amount of data you want to encrypt is often much larger than the block size. So, we either need to create more and more block ciphers of almost every size, or we come up with a way of using our block cipher to encrypt larger amounts of data. This method is called a mode of operation.
To use the most simple case as an example, consider AES in ECB mode. ECB mode tells us that we need split our plaintext string into sections of 128 bits (possibly after some padding scheme). Then, each section is encrypted using AES, and the resultant encryptions are then concatenated to form our output ciphertext. AES simply performs encryptions of the plaintext blocks we give it, whereas ECB allows us to encrypt arbitrarily large amounts of data.
For descriptions of many different modes of operation and a discussion of their merits/weaknesses, you might be interested in this paper by Rogaway, and section 2.3 provides his formalisation of a mode of operation.
share|improve this answer
Paper? More like a novel! But an exceptionally good paper/novel all the same... – Reid Oct 18 '13 at 19:11
A "cipher" is the algorithm which encrypts and decrypts data, while the "cipher-mode" defines how the cipher encrypts and decrypts it.
In other words: ciphers are the cryptographic algorithms that you use to encrypt/decrypt data, while cipher-modes define the "mode of operation" for applying the cipher. Both are complementary and can be chosen separately.
In fact, you could think of it like this: if you choose a cipher it's like choosing what car you want to drive, while choosing a cipher-mode defines how you want to drive that car.
What might be interesting for you to know: if you do not choose a specific cipher-mode, you'll always find yourself using the default cipher-mode called "ECB" (Electronic CodeBook).
For an overview of different cipher-modes, I would like to point you to Wikipedia's "Block cipher modes of operation" article.
Last but not least, here are two examples I've quickly wrapped up to show you where exactly the "cipher" plays a role, and where the "cipher-mode" comes in:
(The default, classic mode of encryption/decryption; but not really recommended due to potential security issues.)
ECB example
(One of many cipher-mode options that - compared to ECB - represents a safer encryption/decryption mode.)
CBC example
share|improve this answer
"ciphers are the cryptographic algorithms that you use to secure data" - sorry if this is overly critical, but I think this sentence is unclear. Arguably the mode-of-operation is also the algorithm "you" use to secure data, the cipher is the algorithm that the mode uses to ensure it's secure? As such, I don't think this helps explain the distinction. Other than that, very nice answer (good idea to use the diagrams) – figlesquidge Oct 18 '13 at 15:39
_USER_ As long as we both agree that the "cipher" is the algorithm that encrypts/decrypts your data, while the "cipher-mode" defines the mode of operation for applying the cipher, we're fine. ;) I reworded that line a bit to avoid potential confusion. Thanks for the heads-up… – e-sushi Oct 18 '13 at 17:59
In general, a cipher is simply any algorithm for encrypting data. It's a really broad term, and might cover anything from ancient substitution ciphers like the Caesar cipher to modern-day public-key ciphers like RSA.
In modern cryptography, there are two commonly encountered types of symmetric (i.e. not public-key) ciphers: block ciphers and stream ciphers. A block cipher encrypts a block of, say, 64 or 128 bits of data, mapping it to another such block of the same size. AES, a.k.a. Rijndael, is one well known example of a block cipher. A stream cipher, on the other hand, can encrypt an arbitrarily long stream of bits, turning it into another (typically slightly longer) bitstream. The RC4 algorithm is a fairly well known example of a a stream cipher.
On its own, a block cipher is obviously not nearly as useful as a stream cipher, at least unless you just happen to need to encrypt some very short messages that fit inside one block. However, it turns out that block ciphers are a lot more versatile than stream ciphers as building blocks of other cryptographic tools, such as hash functions and message authentication codes. Also, there's an extensive body of research on the construction and cryptanalysis of block ciphers, whereas relatively little is known about what makes a dedicated stream cipher (i.e. one not based on a block cipher) secure. Thus, with the exception of a few dedicated stream ciphers like those in the eSTREAM portfolio, almost all modern cipher design and analysis effort is focused on block ciphers.
But for practical encryption, you still want a stream cipher. This is where the modes of operation come in. Basically, a mode of operation is a method for turning a block cipher into a stream cipher.
For example, if you want to encrypt a bunch of text with AES, you don't use the AES block cipher directly — the text probably wouldn't fit inside one AES block anyway. Instead, you use a stream cipher built from AES using a suitable mode of operation, such as AES-CBC or AES-CTR, or even an authenticated encryption mode like AES-GCM or AES-SIV.
The nice thing about building stream ciphers out of block ciphers like that is that we can prove the security of the resulting stream cipher (in the sense of ciphertext indistinguishability under an appropriate attack model), provided that the underlying block cipher satisfies its own security assumptions (basically, is a pseudorandom permutation). Since we know a lot more about designing secure block ciphers than we know about stream ciphers in general, this is a very attractive feature. Also, as noted above, the same block cipher can be used in other ways to construct many other useful cryptographic tools, which also enjoy similarly provable security.
share|improve this answer
Your Answer


Take the 2-minute tour ×
Say you're given a ordered set of $n$ relatively prime elements, $a_1,\dots,a_n$ in a principal ideal domain $D$. If I relabel these elements $a_{11},\dots,a_{1n}$ in the same order, is it possible to find some remaining $a_{kj}$ in $D$ such that $(a_{kj})$ is an invertible $n\times n$ matrix over $D$?
share|improve this question
In a more general setting, this became known as Serre's problem, and later the Quillen-Suslin Theorem. – Gerry Myerson Oct 28 '11 at 22:23
_USER_: Can you indicate how this is related to Quillen-Suslin? – Soarer Oct 29 '11 at 4:38
_USER_, sorry, it's a bit out of my depth. Some statements of the problem/theorem don't look anything like Aria's qiestion, but if you type Quillen Suslin matrix into a search engine you will probably find some references that bring out the relation. – Gerry Myerson Oct 29 '11 at 8:17
_USER_, Here's a reference: Moshe Roitman, Completing unimodular rows to invertible matrices, J. Algebra 49 (1977), no. 1, 206–211, MR0453779 (56 #12033). From the review: Quillen's solution of Serre's problem implies that if $R$ is a commutative ring, then any unimodular row over $R[x]$ which contains a unitary polynomial is completable to an invertible matrix. The author shows.... Other related results on this completion problem are discussed. – Gerry Myerson Oct 31 '11 at 6:11
2 Answers 2
We can prove this by induction. For $n=1$, the set $\{a_1\}$ is relatively prime if and only if $a_1$ is a unit, and thus $(a_{11})$ is invertible.
So assume that we can extend any set of $n$ relatively prime elements to an invertible matrix, and let $n+1$ relatively prime elements $a_1,\dotsc,a_{n+1}$ be given. Let $g=\gcd(a_1,\dotsc,a_n)$. Then we can write $a_i=gb_i$ for $1\le i\le n$, with the $b_i$ relatively prime, and we can extend the $b_i$ to an invertible $n\times n$ matrix $B$. If we multiply the first row of $B$ by $g$, we can place it into the upper left $n\times n$ block of the matrix $A$ to be constructed, and we'll have $a_i=gb_i$ in the right place for $1\le i\le n$. Now place a multiple of the first row of $B$ into the $n+1$-th row of $A$, with the multiplier $r$ yet to be determined, and fill the $n+1$-th column with zeros except for the first and last elements $a_{n+1}$ and $s$, with $s$ yet to be determined. Now the determinant of the upper left $n\times n$ block is $g\det B$, and the determinant of the lower left $n\times n$ block is $(-1)^{n+1}r\det B$, so by Laplace expansion the determinant of the entire matrix $A$ is
$$\det A=sg\det B+ a_{n+1}r\det B=(sg+ ra_{n+1})\det B\;.$$
Since $a_1,\dotsc,a_{n+1}$ are relatively prime, $g$ and $a_{n+1}$ are relatively prime. Thus we can choose $r$ and $s$ such that the expression in parentheses is $1$ and $\det A = \det B$. But a matrix over a commutative ring is invertible if and only if its determinant is invertible (see Do these matrix rings have non-zero elements that are neither units nor zero divisors? and necessary and sufficient condition for trivial kernel of a matrix over a commutative ring). Thus, since $B$ is invertible, $A$ is invertible.
share|improve this answer
There is much written on this and related problems, e.g. it is the special case $\rm\:k=1\:$ of below.
MR 82k:15013
Gustafson, William H.; Moore, Marion E.; Reiner, Irving
Matrix completions over Dedekind rings.
Linear and Multilinear Algebra 10 (1981), no. 2, 141--144.
Let d be any element of the ideal generated by the k by k minors of a k by n matrix M over a Dedekind domain R. The authors show that M can be "completed" to form the top k rows of some invertible n by n matrix of determinant d.
In fact, their proof works if R is any Prufer domain whose finitely generated ideals can be generated by $\ 1\ 1/2\ $ elements; merely precede their lemma by the proof of the formula $\rm\ A \oplus B \cong R \oplus AB\ $ given in Theorem 4.1 of R. C. Heitmann and the reviewer [Rocky Mountain J. Math. 5 (1975), 361--373; MR 52 #3141].
Reviewed by Lawrence S. Levy 91k:15028
share|improve this answer
Your Answer


text:
Analysis on Level of Safety Performance and Occupants' Satisfaction in Low Cost Housing
The general building conditions in low cost housing are part of human's quality indicator. However, there are rising issues on the safety performance of the housing since the occupants are inclined to perceive safety hazards. Therefore, this paper explores the concept of Post Occupancy Evaluation (POE) as safety performance tool. This research conducted a survey on safety performance and occupants' satisfaction to 24 numbers of low cost housing at Kuala Lumpur, Malaysia. The correlation result shows that safety performance has a significant relationship with occupants' satisfaction. The findings supported the application of POE as the tool for safety performance.
Keywords: Post Occupancy Evaluation; Low Cost Housing; Safety Performance;Occupants' Satisfaction;
eISSN 2514-751X © 2018. The Authors. Published for AMER ABRA cE-Bs by e-International Publishing House, Ltd., UK. This is an open-access article under the CC BY-NC-ND license (_URL_ Peer–review under responsibility of AMER (Association of Malaysian Environment-Behaviour Researchers), ABRA (Association of Behavioural Researchers on Asians) and cE-Bs (Centre for Environment-Behaviour Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia.

source: m-a-p/FineFineWeb


Open and closed loop control system essay
If the closed loop system is stable is to investigate if system by looking at properties of the open loop transfer consider a temperature control system. Step motor systems are a bedrock of the motion control industry here we explain the differences between the open-loop system vs closed-loop system. Difference between open loop & closed loop systems march 10th, an open-loop control system takes input under the consideration and doesn't react on the feedback . By contrast, an open-loop control system doesn't have or doesn't use feedback figure 1 a basic closed-loop control system is shown in figure 1.
open and closed loop control system essay In an open-loop control, the system does not measure the conform to the desired output in a closed loop control the system includes a sensor to.
Control system intro - difference between open loop and closed loop control system for students of btech, be, mca, bca, bsc, msc, courses - as per ip . Closed-loop servo you are a closed loop motion control system consists of a motor, amplifier when open-loop stepper performance isn't suitable for . Motor learning - ch 5 open-loop example: in a closed loop control system feedback is used to make corrections to an ongoing movement . They are open loop control system and closed loop control system the disadvantages of open loop system are the bandwidth of open loop control system is less.
Control system | closed loop open loop control advantages of closed loop control system closed loop control systems are more accurate even in the presence of non . The main purpose of experiment introduce to open-loop and closed-loop control system we have tried to learn how to use matlab scripts to create mathematical model of a dc motor by open loop and closed loop control systems and we create simulink. Types of control systems there are two types of control systems namely: 1 open loop control systems (non-feedback control systems) 2 closed loop control systems (feedback control systems). Tutorial on types of control systems: open loop, closed loop, feedforward and feedback. Electronics tutorial about how an open-loop system and open-loop control systems if the dryers door was open it would be detected and closed white papers .
Between a closed loop and an open loop system represent open and closed loop systems of control so how do closed loop systems apply to. Open-loop motorized venetian blind control systems open-loop figure 2 open-loop motorized venetian blind control system closed-loop motorized venetian . Open-loop and closed-loop robust optimal control of batch open-loop and closed-loop system is provided timization papers is the lack of a systematic analysis of. Open and closed loop control one way of examining control systems is to decide whether open or closed loop control is being used open loop control open loop control is a system with no feedback ie there is no way to monitor the process to find out if the control system is working effectively. Motor modeling and position control about transient response characteristics of typical 2nd order systems figure 1: open loop control closed loop control .
Open and closed loop control system i shall be looking at the differences between open loop control systems, the whole essay and download the pdf for . Explore open-loop control systems by walking through some introductory examples open-loop systems are found in every day appliances like toasters or showers open-loop control is easy and conceptually simple. Examples of closed loop systems: 1 the speed control on an automobile essay on vagina monologue 5 answers. In this assignment i shall be looking at the differences between open loop control systems, closes loop control systems and also looking at and identifying the input, output and feedback gained. Via youtube capture difference between open loop and closed loop control systems - control systems | ekeedacom - duration: 7:03 ekeeda 24,442 views.
open and closed loop control system essay In an open-loop control, the system does not measure the conform to the desired output in a closed loop control the system includes a sensor to.
Michaelbarr-july 31, 2002 introduction to closed-loop control most control systems utilize feedback in some manner. The benefits of a closed-loop system open-loop and closed-loop are control systems open-loop systems operate in a "manual" mode (requires a person. What are the advantages and disadvantages of an open–loop open loop system which is also called as manual control system closed loop system which is also .
They are open loop control system and closed loop control system the closed loop system with positive feedback signal connected to its input is called . Closed-loop and activity-guided optogenetic is well-suited for closed-loop control in biological systems open-loop and closed-loop optogenetic control (a) .
Automation and control systems – amem 326 dr sotiris omirou 2 consider an open-loop system for switching on and off the street lamps along a road. Marketing assignemnt systems thinking - closed loop control (essay sample) systems thinking - closed loop control the most important element of system .
open and closed loop control system essay In an open-loop control, the system does not measure the conform to the desired output in a closed loop control the system includes a sensor to. open and closed loop control system essay In an open-loop control, the system does not measure the conform to the desired output in a closed loop control the system includes a sensor to.
Open and closed loop control system essay
Rated 3/5 based on 26 review
Download
2018.


Whose Level of Service is the City Protecting? by Greg Hayes
Sometimes walking in San Francisco doesn't feel right. The urge to jaywalk and the quick analysis: when is the light going to change? Can I make it alive across these four lanes of speeding cars? The light finally changes, but it is not that easy. It is not uncommon that, thanks to the standard traffic engineering, pedestrians and bicyclists are forced to wait through two signal cycles in order to pass through one intersection. You start to suspect that pedestrian and bicycle movements are considered second class
Your suspicion is probably correct. The vast majority of the city's surface street space is judged by its ability to move motor vehicles, through the use of a rating system known as the Level of Service (LOS). This national standard measures the amount of automobile traffic a roadway can accommodate "without undue delay, hazard or restriction to the driver's freedom to maneuver."
The idea can be seen as something of a motor vehicle user's bill of rights, in which the driver's "freedom to maneuver" is the central concern. Basically, one type of citizen - a person driving a car - has more access to the public-right-of-way than any of its other users.
The LOS works like this: a roadway has a certain capacity of automobiles it can sustain before delay, hazard, and maneuvering ability are compromised to an unacceptable level. The successive stages of traffic dysfunction are assigned a letter rating which is set upon average delay time for cars. The best-case scenario is LOS A, with minimal delay times, etc. The worst is LOS F which indicates "forced flow" - basically the stage before total gridlock occurs. When roadways drop below failing level to LOS E, they fail the standard's appraisal, perhaps prompting a road widening, cutting the sidewalk back, or rejecting a proposed bike lane.
2 views of "forced flow" at the Panhandle to Golden Gate Park bike/pedestrian path.
Consider the double-crosswalk design of Stanyan and the Panhandle bikeway where ped/bike traffic seeking to enter the park is forced to wait through two separate light cycles just to maneuver though one intersection. The Golden Gate Park Master Plan and the San Francisco Bicycle Plan both call for a dedicated signal phase specifically designed to carry ped/bike traffic through the intersection in one movement. But the DPT hasn't allowed this for many years. Ask them why and they say because adding a new signal phase for the ped/bike traffic will make the intersection drop below failing LOS levels.
Here's where things really start to get twisted: what the traffic engineers are basically telling the people of San Francisco is that they cannot allow adequate pedestrian and bicycle facilities to be built because they will "cause congestion" and disturb the motor vehicle traffic flow that we are barely maintaining right now. The problem is one of abject, overt discrimination. Vast amounts of public time and space are appropriated and reserved for one mode of movement at the expense of all others. The LOS standard creates and perpetuates this situation and is constantly cited and invoked as means of denying pedestrian and bicycle facility improvements.
The SFBC will continue to advocate for an LOS-type measurement which actually takes other road users into account. After all, don't we all have the right to move down the street "without undue delay, hazard or restriction?" According to those in charge of our city's streets, apparently not.


text:
Baleage vs. Haylage: What's really the difference?
Listen to a discussion of the content in this article on this episode of the BeefWatch podcast. You can subscribe to new episodes in iTunes or paste _URL_ into your podcast app.
Often times the terms baleage and haylage are used interchangeable in conversation due to the state or country of the farm/ranch or simply by the type of operation. So how are baleage and haylage different and why are they used?
The ensiling or fermentation process of preserving forages takes place in both haylage and baleage, hence the names. Baleage can be confused with traditional dry hay because it is still a square or round bale, but it is simply hay that is too moist to store safely as dry hay so it is wrapped or otherwise sealed in plastic. Baleage can be fermented as individual bales or in a tube/inline.
Both baleage and haylage begin with mowing the forage and combining into a windrow typically. The next step is where the differences begin to be more apparent. Haylage is forage chopped using a silage chopper and packed in a bunk, silo, or bag. Some producers may chop right after the mower or allow for some minimal drying prior to chopping to reach a moisture content of 60-70 percent. This is sometimes referred to as the wilt stage and also may be referred to as silage. This is a common moisture for producing haylage although haylage is more commonly chopped at a lower moisture content of 40-60 percent, which also may be called low-moisture haylage. Producing chopped silage is a tried and true method that continues to produce high quality forage with which most producers are knowledgeable or at least familiar. Neighbors or silage crews can usually be found easily and are able to perform all the tasks associated with making silage or haylage. Haylage may not be an option for producers who do not have the equipment needed to feed a silage. In this case, baleage may be a better option, with minor equipment changes needed to feed and with more management flexibility than haylage.
Baleage is partially dried forage, preferably 45-55 percent moisture, which is baled and wrapped with at least 6 layers of 1 mil plastic. Monitoring the moisture content is critical in reducing the risk of spoilage once baled. The process of fermentation in baleage is slower and less complete compared to haylage or silage due to a more loosely packed forage (more oxygen), a larger particle size (less available sugars), and lower moisture, typically. The slower fermentation results in a pH higher than that of haylage. A pH of around 5.0 is present in the bales, which results in more challenging preservation during the fermentation process.
Baleage can create high quality forage if done properly. Some advantages over dry hay include less loss during storage, fewer weather delays at harvest, and faster turnaround from when the forage is down in both regrowth and time on the ground. The equipment changes are not significant but need to be considered. Wrapping equipment is cheaper than a silage chopper, but handling the bales requires different equipment than the classic bale spear or grapple. Disadvantages include getting forage baled at the best moisture content, wrapping within the first 12-24 hours to minimize damage and quality loss, plastic maintenance if holes occur by the environment or animals, plastic disposal, and reduced ability to transport without proper equipment.
Baleage and haylage produce high quality feed when harvested and stored correctly. High quality baleage may be utilized as a cheaper protein supplement alternative on winter range. Each have advantages and disadvantages. While distinct processes result in two different products, the terms haylage, baleage, wet hay, chop, wilt silage, or another are often used interchangeably in conversation. Being clear on the method being discussed is important when attempting to produce a high quality forage for livestock.
Interviews with the authors of BeefWatch newsletter articles become available throughout the month of publication and are accessible at _URL_

source: openbmb/Ultra-FineWeb


text: Drool may be gross, but it's a powerful fungus fighter, according to new research. Biologists collected saliva samples from sedated moose (Alces alces) and European reindeer (Rangifer tarandus). They also grew red fescue, a grass that the two animals commonly munch on in Sweden. The scientists then conducted two experiments. They added the saliva to test tubes teeming with colonies of the fungus Epichloë festucae, which often lives within the grass and helps produce toxic chemicals to ward off ravenous grazers like livestock, and also to recently trimmed grass infected with the fungus. The latter simulated how grass gets ripped and doused with slobber when it's been chomped on by a herbivore. Compared with fungi samples treated with water, moose and reindeer saliva slowed the growth of the fungi. When applied to clipped grass, moose drool reduced the production of the toxic chemicals between 41% and 70%, whereas grass that was not treated with saliva actually doubled in its release of toxic chemicals, according to a study published online today in Biology Letters. The results suggest that large mammalian herbivores have evolved the ability to fight back against plant defenses to either detoxify their greens or curb venomous chemical production.


text:
Bicontinuous interfacially jammed emulsion jels (bijels) are new multiphase soft materials in which two interpenetrating regions of immiscible liquids are stabilized by a jammed monolayer of colloidal particles, sitting at the interface between the two liquids. Such materials were first predicted via (Lattice-Boltzmann) computer simulation and subsequently realized in the lab, with mixtures of water and lutidine (W/L) stabilized via silica colloids with near-equal affinity to both species. Bijels properties are predicted to be highly tunable in terms of the size and volume fraction of the solid particles and perhaps also their shape, say ellipsoids versus spheres, over a broad range of scales.
We plan to perform systematic studies of the morphological and mechanical properties of the bijel metastable structure, i.e. pore size and elasticity as a function of colloidal size and volume fraction. More specifically, we shall investigate the effects of the particle radius and volume fraction on the morphology, pore size distribution and resulting mechanical properties of the bijels for different types of motifs.
For many applications, say tissue engineering, it is imperative to access pore sizes above 100 µm, which appears problematic with standard bijels. This can be achieved by a variant of bijels, known as bridged bijels, in which one phase contains a network of colloidal-bridged droplets. This dual morphology results from combined spinodal decomposition and nucleation and growth in a binary mixture containing neutrally wetting colloids with selective affinity for one liquid phase. Likewise bijels, the mechanical and morphological properties of bridged-bijels are highly sensitive to the physical-chemical properties and volume fractions of the colloidal particles.


text:
When you want to set off a paragraph with a horizontal line, you can switch from the keyboard to the mouse and click the appropriate border tool — or you can simply type it in. For example, suppose you would like to separate the following sentence from the rest of Section One:
After you type the sentence, press Enter, type three hyphens, and then press Enter again, as shown below. (I've turned on the Show/Hide button to reveal the keystrokes.)
Word draws a single line above the second paragraph mark and positions the insertion point marker to begin the next paragraph:
If you prefer a thicker line, substitute the underscore (_) character for the hyphen. Using an equal sign (=) will produce a double line. The tilde character (~) will produce a wavy line, while an asterisk (*) will produce a dotted line. Finally, typing the number sign (#) three times produces this border:
Note that Word's AutoCorrect border option must be set for these keys to work. Go to Tools | AutoCorrect. (In Word 2007, click the Office button, click the Word Options button, point to Proofing in the left column, and then click the AutoCorrect Options button.)
In the AutoCorrect Dialog box, under the Apply As You Type section, select the Border Lines check box:
Miss a Word tip?
Check out the Microsoft Word archive and catch up on other Word tips.
Help users increase productivity by automatically signing up for TechRepublic's free Microsoft Office Suite newsletter, featuring Word, Excel, and Access tips, delivered each Wednesday.


Dirt road
From Wikipedia, the free encyclopedia
 (Redirected from Fieldway)
Jump to: navigation, search
Cattle on a dirt road in Paraguay.
A dirt road is an unpaved road made from the native material of the land surface through which it passes, known to highway engineers as subgrade material. Dirt roads are suitable for vehicles; a narrower path for pedestrians, animals, and possibly small vehicles would be called a dirt track—the distinction is not well-defined. Unpaved roads with a harder surface made by the addition of material such as gravel and aggregate (stones), might be referred to as dirt roads in common usage but are distinguished as improved roads by highway engineers. (Improved unpaved roads include gravel roads, laterite roads, murram roads and macadamized roads.)
Compared to a gravel road, a dirt road is not usually graded regularly to produce an enhanced camber to encourage rainwater to drain off the road, and drainage ditches at the sides may be absent. They are unlikely to have embankments through low-lying areas. This leads to greater waterlogging and erosion, and after heavy rain the road may be impassable even to off-road vehicles. For this reason, in some countries, such as Australia and New Zealand, they are known as dry-weather roads.
Dirt road in Switzerland for agricultural use.
Dirt roads take on different characteristics according to the soils and geology where they pass, and may be sandy, stony, rocky or have a bare earth surface, which could be extremely muddy and slippery when wet, and baked hard when dry. They are likely to become impassable after rain. They are common in rural areas of many countries, often very narrow and infrequently used, and are also found in metropolitan areas of many developing countries, where they may also be used as major highways and have considerable width.
Terms similar to dirt road are dry-weather road, earth road, or the "Class Four Highway" designation used in the People's Republic of China. A track, dirt track, or earth track would normally be similar but less suitable for larger vehicles.
Driving on dirt roads[edit]
Detail of a dry, loamy road.
While most gravel roads are all-weather roads and can be used by ordinary cars, dirt roads may only be passable by trucks or four-wheel drive vehicles, especially in wet weather, or on rocky or very sandy sections. It is as easy to become bogged in sand as it is in mud; a high clearance under the vehicle may be required for rocky sections.
Driving on dirt roads requires great attention to variations in the surface and it is easier to lose control than on a gravel road. In addition to the hazards already mentioned, and potholes, ruts and ridges, problems associated with driving on gravel roads include:
 - sharper and larger stones cutting and puncturing tires, or being thrown up by the wheels and damaging the underside, especially puncturing the fuel tank if not shielded
 - stones skipping up hitting the car body, lights or windshields when two vehicles pass each other
 - dust thrown up from a passing vehicle reducing visibility
 - 'washboard' corrugations cause loss of control or damage to vehicle systems such as suspension and steering
 - Skidding (loss of traction) on mud after rain.
Dirt road in Brazil
A dirt road showing a heavy amount of washboarding damage
This is an 1880's photo of 653 W Wrightwood (now 655 W Wrightwood) in the Lincoln Park Neighborhood of Chicago, Illinois. Note the wooden sidewalk, dirt road and lack of buildings surrounding the edifice.
Laterite and murram roads[edit]
In Africa parts of Asia, and parts of America, laterite soils are used to build dirt roads. However laterite, called murram in East Africa, varies considerably to earth and sand. It ranges from a hard gravel to a softer earth embedded with small stones. Not all laterite and murram roads are therefore strictly gravel roads. Laterite and murram which contains a significant proportion of clay becomes very slippery when wet, and in the rainy season, it may be difficult even for four-wheel drive vehicles to avoid slipping off very cambered roads into the drainage ditches at the side of the road. As it dries out, such laterite can become very hard, like sun-dried bricks.
See also[edit]


text:
1947 Assignment illustrations and clipart. Affordable Downloads for just with thousands of images added daily. Blank paper desk spiral Blank paper.
Finally, underneath the illustration, or on another piece of paper, write or type one complete, detailed paragraph (5-7 sentences) explaining why this setting is.
Unit 4 Externally Set Assignment. To be issued to For this paper you must have: There is no size restriction on work produced for this paper. Advice illustrations by Arthur Radebaugh or John Berkey or work by design groups such as.


text:
Freelancing is a business and the way you will handle your taxes working as a freelancer will be different than someone who is solely employed by a corporation. If you are working full-time as a freelancer, whether it is as a computer consultant, writer, artist or any other job, there are several things to keep in mind.
Income tax is a statutory liability of those persons who make more income. The employees make income from salary and freelance work requires different approach for tax filing. If the freelance income is derived in their name, but not in the name of any company or firms registered, the following methods can be suitable to adopt.
How Bloggers / Freelancers Calculate Taxable Income for Income Tax Purpose
Step 1: Calculate your total revenue earned
In India, financial year starts from 01 April and ends on 31 March. So, for income tax purpose, you need to calculate the overall income you've earned between 01 April to 31 March.
Total revenue calculation is done after the financial years ended (i.e. after 31 March). You need to pay your income tax before 31 July — so you need to do all the tax calculations sometime between 01 April and 31 July.
Step 2: Calculate your expenses
As a full-time blogger/freelancer, you are considered to be running a business. Businesses earn revenue but they also have certain expenses. You need to pay income tax only on the net profit your have made in previous financial year. In order to calculate profit, you would need to calculate total expenses that you incurred in earning your revenue.
Step 3: Deduct expenses from revenue to get net profit
Now that you have added up both your total revenue and total expenses, it is time to find out your net profit. For this, simply subtract expenses from revenue.
profit = revenue – expenses
Step 4: Subtract the deductions allowed from your net profit
Are you liable to pay income tax on the entire net profit? No!
There is a list of deductions allowed according to the Section 80 in Income Tax Act, which applies to every individual calculating their taxable income. So, as a blogger / freelancer, you can also avail of these deductions.
At present you can save tax on Rs. 1,50,000 under various deductions allowed under Section 80. You can make specific investments of up to Rs. 1,50,000 and save tax on this amount.
So, if you really make these investments, you can further subtract Rs. 1,50,000 from your net profit to get your final taxable income.
Final Taxable Income = Revenue – (Expenses + Various Deductions)
We recommend that you consult a good financial advisor in order to take the proper benefit of the deductions allowed.
Step 5: Now, dear blogger, calculate your income tax!
Finally, it's time to calculate your income tax liability. At present, Indians need to pay income tax according to the following slabs. Please note, that these slabs and tax percentage are altered from time to time (especially in the General Budget of India).
If you are a full-time blogger or freelancer, you need to fill ITR-4 while filing your income tax return. ITR-4 is meant for professionals and business persons.
If you are a part-time blogger or freelancer then you must be file ITR for your overall income. You can just show your income from blogging and freelancing as income from other sources in the ITR you already file.


text:
For a academic/scientific software project we try to embed UE 4.8.1 into an existing VS 2013 C++ application and use the engine as the visualization tool.
Main goal: Our C++ application provides the UI and mathematical algorithms. UE4 should handle the visualization part, which is called and controlled from our UI. Users should be able to preselect their own uproject files and start the visualization with a button-press event.
We already checked the documentation, the answerhub, and the forum but could not find clear answers to the following questions:
What is the recommended way to embed the UE4 framework into a Microsoft VS 2013 C++ software project? Which compiling options are important if we add the UE4 project file (UE4.sln) to our VS project? Does anyone have experience with that?
For our visualization process we need to control the main engine loop or something similar in order to interrupt and continue the game presentation/visualization at certain time points. Pausing the running visualization with a customized game menu would be ok as well. What is the recommended way to adapt the engine loop. Should we write own control classes derived from the UE4 main engine loop class to control the visualization process? Does anyone have experiences with customizing the UE4 engine loop? What is the best way to do this?
We would really appreciate if anyone could help us or share their experiences with us.


text:
The new vapor retardant is a polyamide film that can become more than 20 times more permeable at high relative humidity than during times when there is low humidity, such as in the winter.
More typical polyethylene vapor retardants allow moisture to condense on cold surfaces and accumulate in the wall cavity when the seasons change.
The concept of a "smart" vapor retardant was introduced seven years ago in Europe and has become widely accepted there, CertainTeed says.
With a high resistance to water vapor diffusion in winter, says the manufacturer, the pores of MemBrain™ react to increases in the relative humidity so that water vapor can pass through. This lowered resistance supports the drying process.


text:
Analysis of hallucinations and fear complex cause for psychological abnormalities of the protagonist Brutus Jones In Eugene O'Neill's The Emperor Jones
1Dr. M. Nallathambi, T. Gnanasekaran
In order to explore the fundamental themes of human life itself—the endless conflicts of good and evil, of light and darkness, of civilization and savagery, O'Neill experimented with expressionistic techniques in some of his early plays. In The Emperor Jones, published in 1921, O'Neill makes special use of symbolic scenes and sound effects to portray certain psychological states of mind, hallucination and the emotional intensity of his protagonist: Brutus Jones. This study reveals the psychological abnormalities of the protagonist Brutus Jones The Emperor Jones is arranged in eight scenes dramatizing the psychological journey by which of an island in the West Indies to a man acknowledging his guilt, attempting to do away with the evil in himself, and finally accepting his humanity. Central to the process of this journey are Jones' feelings of isolation and his quest for belonging. The present study explains the scene wise summary of the psychological abnormalities, struggles and the tragic end of the hero Brutus Jones.
conflicts, civilization, savagery, psychological states of mind, hallucination, emotional intensity, psychological abnormalities, isolation, humanity, quest for belonging


text:
Managing solar parks for honeybees can have positive impacts on crop yields and thus financial returns. But, it is important to consider the suitability on a site by site basis given the potential implications for wild pollinators and the benefits of managing sites for biodiversity more broadly.
Dr Alona Armstrong
The value of UK agriculture could be boosted by millions of pounds a year if thousands of honeybee hives were deployed on solar parks across the country, a new study reveals.
However, scientists caution that the benefits of managing solar parks for wild pollinators over honeybees should be prioritised where appropriate and should be assessed on a site by site basis.
A team of researchers from Lancaster University and the University of Reading has for the first time quantified the potential economic benefits and costs of installing honeybee hives on solar parks across the UK.
Solar parks are playing an increasingly important role in our national shift towards carbon zero as their contribution to electricity generation rises.
However, solar parks take up a lot of land, and as more parks are created to meet clean energy demand the it is important to look at how they can be used to bring about other environmental or commercial benefits.
One opportunity is to install honeybee hives on solar parks. A lot of solar parks are located in areas of intensive agriculture where many wild pollinator habitats have been lost or degraded. Honeybee hives provide ready-made armies providing a pollinating service to increase crop production in surrounding farmland. Although some honeybee hives have been used on solar parks, the potential economic benefits of this were, until now, unknown.
The research team used detailed land cover maps, such as those produced by the Centre of Ecology and Hydrology, to understand where solar parks are located, as well as crop distribution and rotations, existing data on honeybee hives, crop pollination requirements and crop values.
They also factored in the cost of installing and managing the honeybee hives on the solar parks.
Using crop distribution patterns in 2017, the researchers found that deploying honeybees on solar parks could have raised the value of crop yields that year by £5.9 million.
The study looked at field crops such as field beans, linseed and oilseed, top fruits such as apples and pears including varieties to make cider and perry, as well as soft fruits such as strawberries, raspberries and blackcurrants.
The findings showed that in England the crop that would potentially benefit the greatest from installing honeybee hives is oilseed, because it is so widely cultivated. Though soft fruits, and especially strawberries, would see the greatest economic benefit per land area given their high market value and relatively high dependency on honeybee pollination.
Based on 2017 data then honeybees on solar parks could boost field crop yields by £2.6 million, top fruits by £1.3 million, and soft fruit yields by £1.9 million.
There were also regional patterns in the findings with values being highest in the east and south of England because those are the areas where a greater proportion of oilseed and soft fruits are grown.
They also found that, if taken to the extreme of all UK crops being grown within a 1.5km honeybee foraging radius of solar parks around the UK, then this could boost the value of those crop yields by £80 million a year – but researchers recognise this scenario is unlikely to be possible given other factors.
Given these findings, if UK agriculture wanted to maximise the economic benefits of having honeybees on solar parks then soft fruit growing would need to be prioritised within honeybee foraging zones of 1.5km around solar parks.
However, the researchers are keen to point out that the suitability of placing honeybee hives on solar parks needs to be assessed for each location. This is because not all locations including their climate and soil types are suitable for all crops, and individual farmers have preferences about what and where they produce. Also, different crops vary in their pollination needs and so the research team's results cannot be generalised across all crop types and varieties.
In addition, great care needs to be taken to ensure the honeybees would not be competing with already established wild pollinator species. The researchers also highlight that where possible encouraging wild pollinators would provide greater ecological benefits than installing honeybee hives.
Dr Alona Armstrong, Senior Lecturer at Lancaster University and lead author of the study, said: "Managing solar parks for honeybees can have positive impacts on crop yields and thus financial returns. But, it is important to consider the suitability on a site by site basis given the potential implications for wild pollinators and the benefits of managing sites for biodiversity more broadly."
Professor Simon Potts from the University of Reading and co-author of the paper said: "Our study demonstrates how multi-disciplinary research can find novel land management practices which can simultaneously benefit energy producers, farmers, beekeepers and consumers."
The researchers' findings will help inform energy policy, future business cases for future solar parks, as well as informing sustainable investments and decisions about including honeybee hives into energy and land management.
The findings are outlined in the paper 'Honeybee pollination benefits could inform solar park business cases, planning decisions and environmental sustainable targets', which has been published by the journal Biological Conservation.
The Latest on: Solar parks for honeybees
- Dunfermline Learning Campus will be good for the birds and the beeson June 30, 2022 at 8:13 am
SCHOOL pupils will be able to find out about the birds and the bees – by wandering around the grounds of the new Dunfermline Learning Campus.
- 8 sustainable hotels around the world for conscious and mindful travelon June 28, 2022 at 5:00 am
Here is our handpicked list of eight sustainable hotels around the world for your next conscious travel trip. Get Spoilt Silly and Sustainably at Château Saint-Martin & Spa | France Spread over 34 ...
- Sunday at Glastonbury: Kendrick Lamar, Diana Ross and Jack White – as it happenedon June 26, 2022 at 3:49 pm
The US rap star headlined the main stage on the last night of the festival, while Pet Shop Boys, Charli XCX, Jarvis Cocker and a host more brought the festival to a close ...
- Glastonbury 2022: Sunday's build up to Kendrick Lamar, with Diana Ross, Jack White and more – liveon June 26, 2022 at 12:39 pm
The festival enters its third and most sunshiny day with Ross in the traditional afternoon 'legends' slot, and sets from Lorde, Elbow and many more still to come – follow along for reviews, photograph ...
- The 42 Best Gifts for Dadson June 22, 2022 at 11:36 am
SpaceTime Coordinates will create a personalized art print depicting how the solar system looked at a ... or spooned onto yogurt, honey is the sweetener that dazzles, with a flavor complexity ...
- Once-Common California Bumble Bees Have Gone Missingon June 22, 2022 at 6:51 am
A census of California bumble bees failed to locate several once-common species, including the formerly abundant Western bumble bee, a key pollinator for many wild plants and crops. "We didn't find it ...
- Thousands Of Bees Removed From Nebraska Homeon June 22, 2022 at 12:09 am
OMAHA, Neb. (AP) — About 6,000 bees were recently removed from inside the walls of an Omaha couple's 100-year-old home. Thomas and Marylu Gouttierre told the Omaha World-Herald they have been ...
- 6,000 bees removed from Nebraska home: 'You could hear the buzzing'on June 20, 2022 at 7:36 am
A home in Nebraska made plenty of buzz after thousands of bees were removed from its walls. The Omaha Bee Club removed about 6,000 of the insects from a 100-year-old house belonging to Thomas and ...
- Renewable energy or reliable energy, but not bothon June 16, 2022 at 2:59 pm
bees, bats or marsupials - not green at all. The ALP has also revived the hoary plan to run an extension cord to Tasmania. Naturally some greedy green Tasmanians want to keep all that wind, solar and ...
- June's strawberry moon will light up the sky this weekon June 15, 2022 at 8:27 pm
In Europe, this moon is often called the honey moon or the mead moon ... There will be one more total lunar eclipse and a partial solar eclipse in 2022, according to The Old Farmer's Almanac.
via Bing News
The Latest on: Solar parks for honeybees
via Google News


text:
The 70-gun war ship Resolution, sunk off Sussex in 1703, recently discovered by divers on the seabed in Pevensey Bay, off the Sussex coast.
The site comprises a cluster of at least 45 iron guns lying on top of ballast material, other artefacts and timber hull structure. Archaeological investigations to date have concentrated on confirming the identity of the site to be that of the Resolution primarily through the recording of the ordnance and ballast.
The Resolution was built in Harwich between 1665 and 1667 and was one of only three third-rate vessels built by noted maritime architect Sir Anthony Deane. In 1669, the Resolution was the flagship in an expedition against the Barbary Corsairs and took part in the unsuccessful attack on the Dutch Smyrna convoy, which resulted in the Third Dutch War.
The Resolution sank during the Great Storm on 26 November 1703, after being blown across the Solent, striking the Owers Banks six or seven times before the crew was able to raise a scrap of sail and round Beachy Head. By this time the ship was taking on water, the hold was full up to the level of the orlop beams, and so the decision was made to attempt to beach her in Pevensey Bay. The remains of the vessel had been burned by French Privateers by January 1704.
The 'Great Storm' is well documented in contemporary newspapers and by Daniel Defoe in his work The Storm: An Essay, written in 1704. Other protected warships lost in the same storm comprise the Stirling Castle, Restoration and Northumberland, located on the Goodwin Sands, off Kent.
Substantial sections of the hull of the wrecked warship exist beneath a mound of ballast. This is particularly exciting as in situ preservation of shipwreck material dating from the 17th and 18th centuries is uncommon. Therefore, following further investigations, this wreck may have the potential to be of even greater archaeological and historical importance than is considered at present.
The Nautical Museum's Trust is the legal owner of the Resolution.


text:
98th (Prince of Wales's) Regiment of Foot
|98th (The Prince of Wales's) Regiment of Foot|
|March||God Bless the Prince of Wales|
|Engagements||First Opium War, Second Anglo-Sikh War|
|Disbanded||1881, amalgamated with 64th Foot to become The Prince of Wales's (North Staffordshire) Regiment|
|HRH The Prince of Wales|
|Sir Colin Campbell|
The 98th (Prince of Wales) Regiment of Foot was an infantry regiment of the British Army. It was originally raised in 1824 as the 98th Regiment of Foot, before assuming the title of the 98th (Prince of Wales) Regiment of Foot in 1876. Later, in 1881, following the Childers Reforms of the British Army, the regiment was amalgamated with the 64th Regiment of Foot to become the Prince of Wales's (North Staffordshire) Regiment. As the 64th Foot was senior to the 98th, the 98th became the 2nd Battalion in the new regiment. Throughout the course of the regiment's existence it served mostly overseas in South Africa, China and India.
The 98th Foot was raised in Chichester in 1824 by Lieutenant Colonel Mildmay Fane. It was the sixth regiment to be numbered the 98th Foot. The first Colonel of the regiment was Major General Henry Conran. The first set of colours were presented by the Duchess of Richmond at a ceremony at Chichester on 6 October 1824.
In December 1824 the new regiment was posted to South Africa where for all bar two years of its 13 year tour it was based in Cape Town, the other two years being in Grahamstown. During the entire tour no active service was seen. Returning to England in 1837 the regiment was based for two years in Newcastle upon Tyne where it was frequently called out to support the civil powers during the Chartist unrests. At this point command of the regiment was taken over by its most famous commanding officer, Sir Colin Campbell who commanded the reigment for 12 years between 1835 and 1847.
In 1841 the regiment moved to Ireland but very shortly afterwards was sent to China during the 1st China or Opium War. Arriving in Hong Kong in 1842 it formed part of the 1st Brigade, commanded by Major General Lord Saltoun, along with the 26th Foot, the Bengal Volunteer Battalion and the grenadier and light companies of the 41st Madras Native Infantry. The brigade advanced on Chinkiang and after an ineffective pursuit of retreating Chinese forces took part in the final advance on Nanking. During this war very few battle casualties were taken but over 50 died from cholera with another 200+ unfit for duty. As a result of its participation in the Opium War, the regiment was awarded its first battle honour "The DRAGON superscribed CHINA". A move to Hong Kong followed where the appalling death rate from disease continued with over 500 dying and sick.
The next move was to India in 1846. Initially the regiment was based in Calcutta (Kolkata) and Dinapore, however, in 1848 it moved to the Punjab where, although not directly engaged in the Second Anglo-Sikh War, a second battle honour — PUNJAUB — was awarded. From here the regiment was one of the first British units to serve on the North West Frontier and spent 1849–1851 in and around the Kohat Pass area. By 1851 the regiment had been abroad for a total of nine years and in that time it had suffered over 1,100 deaths, mostly from sickness, with almost 200 invalided home. The last three years of the posting were spent in Calcutta before the regiment returned to England in 1854.
Following three years on home service the regiment returned to India and the North West Frontier. As a result it saw no service in the Indian Mutiny. Instead it was employed as part of the Sittana Field Force sent to deal with the so called Hindustani Fanatics.
The regiment returned home in 1867 and then in 1870 moved to Ireland for three years. During this time it dealt with minor disturbance including a mutiny by the Tipperary Light Infantry Militia. The Cardwell Reforms were introduced during this period and it was then that the regiment was linked with the 64th (2nd Staffordshire) Foot for the first time.
The next posting was to the West Indies from 1873 to 1880 followed by a move to Malta. It was in Malta following the presentation of what transpired to be the last set of regimental colours by HRH The Prince of Wales that the regiment became the 98th (Prince of Wales's) Regiment of Foot on 27 October 1876.
War broke out in Afghanistan in 1879 and in 1880 in response the regiment moved once more to India being based initially at Karachi. It was here that in 1881 the eventual conclusion of the Childers Reforms took effect and the regiment amalgamated with the 64th Foot to become the Prince of Wales's (North Staffordshire) Regiment. As the junior regiment the 98th Foot became the 2nd Battalion of the new regiment.
In its short life of 57 years, no less than 43 were spent on overseas postings.
Battle honours
The 98th Foot was granted the following battle honours:
- The DRAGON superscribed CHINA (1842);
- PUNJAUB (1848).
On 1 July 1881, the 64th and 98th Regiments of Foot were combined with militia and rifle volunteer units in Northern Staffordshire to form The Prince of Wales's (North Staffordshire) Regiment. The regiment was renamed The North Staffordshire (The Prince of Wales's) Regiment in 1920. In 1959 the North Staffordshire and South Staffordshire Regiments amalgamated to form The Staffordshire Regiment (The Prince of Wales's). In September 2007 The Staffordshire Regiment amalgamated with the 22nd (Cheshire) Regiment and The Worcestershire and Sherwood Foresters Regiment to form The Mercian Regiment, in which the Staffords became the 3rd (Staffordshire) Battalion.
The Dragon device is still carried on the colours and drums of the Mercian Regiment.
- Cook p.33.
- Historical Record p.1.
- Cook p.35.
- Historical Record p.2.
- Cook p.38.
- Cook p.58.
- Cook p.59.
- Cook p.60.
- Historical Record p.3.
- "Cardwell Reforms". Retrieved 30 July 2009.
- Cook p.62.
- "The Mercian Regiment: Regimental Devices and Badges". Retrieved 9 April 2009.
- Parliamentary Debates, House of Commons, 16 December 2004, column 1796.
See also
- Cook, Hugh (1970). The North Staffordshire Regiment (The Prince of Wales's). Famous Regiments. London: Leo Cooper. ISBN 0-85052-056-8.
- An Historical Record of the 2nd Battalion, The Prince of Wales' North Staffordshire Regiment. Mooltan, Punjab, India: F Bremner. 1908.


Often asked: How close to the sidewalk can i build a fence?
How close can you build to a fence?
Fences must not be higher than three metres, or 1.2 metres if the fence is built from masonry. When the lot is adjacent to a residential zone, at least 75 per cent of the part of the fence that is above 1.8 metres in height, must be transparent.
Do I need my neighbors permission to build a fence?
As long as the fence is completely on your property, you can put it up without needing your neighbors permission. If the existing fence is on both your properties, you would need your neighbors permission to take it down.
Can I build a fence next to my neighbors fence?
A general rule (not sure if your neighbors abide to it) is to build the fence 1-2 feet inside your property line. You best option is to ask them to join your new fence to it and get a simple contract to protect yourself. Either that or put up all four sides in your property.
How close to my property line can I build?
1. Side and Rear Yards. Yard structures under six feet in height may be located up to a side or rear property line subject to building code and fire code limitations. Yard structures six feet in height or over shall be located at least three feet from any property line and shall not exceed 12 feet in height.
Can my Neighbour attach things to my fence?
Can my neighbour attach or nail things to my fence? The short answer to this question is, of course, "no". If you own the fence and you have not granted your neighbour permission to do so, they are not allowed to attach or nail things to your fence.
We recommend reading: Readers ask: How can i get free stuff to review?
Can my Neighbour build up to my boundary?
The short answer is "yes, subject to serving a valid notice and following the processes set out in The Party Wall Act. The party wall act only applies to "structures" (ie: a wall with a foundation), it does not apply to timber fences or other screens.
How do you tell if a fence is yours or neighbors?
Determine ownership by occupancy if the fence lies between or directly on the property line. Whoever uses the land up to the fence is considered the owner. If you have grass and mow the area directly up against the fence but your neighbor allows the weeds to grow on his/her side, then you own the fence by occupancy.
When building a fence who gets the good side?
Face the finished side of the fence toward your neighbor
The finished side should face toward your neighbor. Not only is this more polite, but it's the standard. Your property will look a lot nicer with the "goodside facing the outside world. Otherwise, your fence will look like it was installed backward.
What happens if Neighbour refuses to pay for fence?
In most states, adjoining owners must share the cost of the fence. That obligation only occurs if the fence is inadequate or there is no fence. There are exceptions: If one neighbour damages the fence, they have to pay for the entire costs of restoring it.
Can I legally paint my side of Neighbours fence?
If you want to change anything about a fence that legally belongs to your neighbour, you should ask their permission first – even if you're only painting or staining your side of the fence.
We recommend reading: Question: How can i find out if i was adopted?
Who owns the fence between neighbors?
Who owns the dividing fence? In most states, if you and your neighbour are both owner-occupiers, you share equal responsibility for the dividing fence on your land. Generally, that means you pay an equal share of the cost of a 'sufficient' fence. The definition of 'sufficient' differs from state-to-state.
Is it rude to put up a privacy fence?
It is rude to erect a fence in such a way that it extends several inches onto your property. The neighbor will be justified to demand total removal of the fence. The same applies to unruly bushes on your fence that may spread onto the yard of your neighbor.
Can a Neighbours gutter overhangs my property?
It is a well established principle that you own the airspace above your land, so if your neighbour's gutters overhang your land then they may be a trespass, even if you cannot reach them or they don't interfere with the day to day use of your land.
How close can a shed be to a Neighbour's fence?
Within 2 metres of a boundary the maximum height of a shed or any other building is 2.5 metres, but that shed or building can be right up against the boundary. The 3 metre flat roof and 4 metre pitched roof buildings will have to be more than2 metres from the boundary.
How close can a shed be to a neighbor's house?
Any shed must be built at least 2.5m away from the main house. It's advisable to be able to walk round all four sides, or however many you choose. This gives you access for decorating and repair.
Leave a Reply


text:
The stipules are always free from the leafstalk and attached to the twig at small spots just below the leafstalk.
The base of the leafstalk is hollow and in falling off exposes the winter bud.
The Common Locust has several buds under the leafstalk and one above it in the axil.
Stipules small, very narrow and pointed, usually attached part way up to the leafstalk.
leafstalk dark red and jointed above the base, the veins somewhat red-tinted.
In the Sycamore the bud does not show while the leaf remains on the tree, as it is in the hollow of the leafstalk.
leafstalk long, slender, compressed, causing the leaves to tremble continually in the slightest breeze.
Leaves deltoid, wider than long, crenulated all round, both sides smooth from the first; leafstalk compressed; buds glutinous.


Useful tips
How do you fix another instance of this application is already running?
How do you fix another instance of this application is already running?
How to Fix Another Instance Is Running Error in Windows 10 / 11
 1. Fix 1 – Set Workstation Service to Automatic.
 2. Fix 2 – Uninstall Web Companion from PC.
 3. Fix 3 -Update Windows.
 4. Fix 4 -Clean Boot PC from Safe Mode.
 5. Fix 5 – Run SFC Scan.
 6. Fix 6 -Run DISM Scan.
 7. Fix 7 -End Problematic Process from Task Manager.
How do I open another instance of a program?
To open a second window of certain open apps, just hold Shift and click on the icon in your taskbar. For programs like Word, Notepad, File Explorer, and Chrome, this will open a second window with a blank document. You can work in that instance of the app separately from whatever else you already have open.
How do I run another instance of Windows?
First, open the application you want to run in multiple instances. Then, hold down the Shift key on your keyboard and click with your cursor – or tap with your finger – on its taskbar icon. One click or tap opens a new instance, two clicks or taps open two, and so on.
What is the meaning of another instance?
a a different example of the same sort.
How do you stop another instance of Certbot is already running?
You need to kill the other certbot process. You can do that by rebooting the box. Or by killing the specific process.
What is an instance of a program?
An instance is a single copy of the software running on a single physical or virtual server. If you run two copies of the software on the same physical or virtual server, that counts as two instances.
How do I block multiple instances of a program in windows 10?
In order to disable multiple instances of an app on Windows 10, you need to install a free app called SingleInstance. Go ahead and download, and run the app. The app, by default, has one app pre-configured and that's the Calculator app on Windows 10.
How do I block multiple instances of a program in Windows 10?
How do I stop Certbot?
To uninstall certbot-auto , you need to do three things:
 1. If you added a cron job or systemd timer to automatically run certbot-auto to renew your certificates, you should delete it.
 2. Delete the certbot-auto script.
 3. Delete the Certbot installation created by certbot-auto by running sudo rm -rf /opt/eff.org .
How do I uninstall Certbot?
4 Answers
 1. Remove Certbot sudo certbot delete.
 2. Remove Certbot's Apache package sudo apt purge python-certbot-apache.
 3. Disable the SSL config file created by certbot sudo a2dissite 000-default-le-ssl.conf.
What does instance mean?
1 : a particular occurrence of something : example an instance of true bravery. 2 : a certain point or situation in a process or series of events In most instances, the medicine helps. instance.
What is an instance in programming examples?
In programming, an instance is one occurrence of a class or object. For example, a program may have a class/object named Animal, but there could be many instances of Animal, such as lion, cat, and dog.
Related Posts
What happened at the end of American Crime season 1?
What happened at the end of American Crime season 1? In the final episode, the viewer learns that the witness who was key to the Mexican prosecutor's case…
What is theoretical lexicography?
What is theoretical lexicography? Theoretical lexicography is the scholarly study of semantic, orthographic, syntagmatic and paradigmatic features of lexemes of the lexicon (vocabulary) of a language, developing theories…
What does it mean we bow down?
What does it mean we bow down? Definition of bow down to (someone or something) : to show weakness by agreeing to the demands or following the orders…
How does a TV with built-in Wi-Fi work?
How does a TV with built-in Wi-Fi work? Wi-Fi televisions let you view websites without having to use your computer. Wi-Fi televisions require your computer's wireless high-speed Internet…
What are the sauces used in burger?
What are the sauces used in burger? Our top 10 quick burger sauces Classic burger sauce. Stir together 3 tbsp mayonnaise, 2 tbsp ketchup, 25g finely chopped cornichons…
Where can I catch snakehead in NJ?
Where can I catch snakehead in NJ? Top waters to catch snakehead fever include the aforementioned venues in addition to the DOD ponds, Harrisonville Lake, Crystal Lake (Burlington…


slash. If you really want to use backslashes, consider using Sarathy's File::DosGlob, which comes with the standard Perl distribution.
 - Mac OS (Classic) users should note a few differences. Since Mac OS is not Unix, when the glob code encounters a tilde glob (e.g. ~user) and the GLOB_TILDE flag is used, it simply returns that pattern without doing any expansion.
 Glob on Mac OS is case-insensitive by default (if you don't use any flags). If you specify any flags at all and still want glob to be case-insensitive, you must include GLOB_NOCASE in the flags.
 The path separator is ':' (aka colon), not '/' (aka slash). Mac OS users should be careful about specifying relative pathnames. While a full path always begins with a volume name, a relative pathname should always begin with a ':'. If specifying a volume name only, a trailing ':' is required.
 The specification of pathnames in glob patterns adheres to the usual Mac OS conventions: The path separator is a colon ':', not a slash '/'. A full path always begins with a volume name. A relative pathname on Mac OS must always begin with a ':', except when specifying a file or directory name in the current working directory, where the leading colon is optional. If specifying a volume name only, a trailing ':' is required. Due to these rules, a glob like <*:> will find all mounted volumes, while a glob like <*> or <:*> will find all files and directories in the current directory.
 Note that updirs in the glob pattern are resolved before the matching begins, i.e. a pattern like "*HD:t?p::a*" will be matched as "*HD:a*". Note also, that a single trailing ':' in the pattern is ignored (unless it's a volume name pattern like "*HD:"), i.e. a glob like <:*:> will find both directories and files (and not, as one might expect, only directories). You can, however, use the GLOB_MARK flag to distinguish (without a file test) directory names from file names.
 If the GLOB_MARK flag is set, all directory paths will have a ':' appended. Since a directory like 'lib:' is not a valid relative path on Mac OS, both a leading and a trailing colon will be added, when the directory name in question doesn't contain any colons (e.g. 'lib' becomes ':lib:').
SEE ALSO
glob, glob(3)
AUTHOR
The Perl interface was written by Nathan Torkington <_EMAIL_>, and is released under the artistic license. Further modifications were made by Greg Bacon <_EMAIL_>, Gurusamy Sarathy <_EMAIL_>, and Thomas Wegner <_EMAIL_>. The C glob code has the following copyright:
 1. Copyright (c) 1989, 1993 The Regents of the University of California.
 2. All rights reserved.
 3. This code is derived from software contributed to Berkeley by
 4. Guido van Rossum.
 5. Redistribution and use in source and binary forms, with or without
 6. modification, are permitted provided that the following conditions
 7. are met:
 8. 1. Redistributions of source code must retain the above copyright
 9. notice, this list of conditions and the following disclaimer.
 10. 2. Redistributions in binary form must reproduce the above copyright
 11. notice, this list of conditions and the following disclaimer in the
 12. documentation and/or other materials provided with the distribution.
 13. 3. Neither the name of the University nor the names of its contributors
 14. may be used to endorse or promote products derived from this software
 15. without specific prior written permission.
 16. THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ''AS IS'' AND
 17. ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 18. IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 19. ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 20. FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 21. DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 22. OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 23. HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 24. LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 25. OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 26. SUCH DAMAGE.


Abstract
Micro-scale optical components play a crucial role in imaging and display technology, biosensing, beam shaping, optical switching, wavefront-analysis, and device miniaturization. Herein, we demonstrate liquid compound micro-lenses with dynamically tunable focal lengths. We employ bi-phase emulsion droplets fabricated from immiscible hydrocarbon and fluorocarbon liquids to form responsive micro-lenses that can be reconfigured to focus or scatter light, form real or virtual images, and display variable focal lengths. Experimental demonstrations of dynamic refractive control are complemented by theoretical analysis and wave-optical modelling. Additionally, we provide evidence of the micro-lenses' functionality for two potential applications—integral micro-scale imaging devices and light field display technology—thereby demonstrating both the fundamental characteristics and the promising opportunities for fluid-based dynamic refractive micro-scale compound lenses.
Introduction
Micrometre-scale optical elements have contributed significantly to the miniaturization of devices and instrumentation. Static micrometre-sized lenses have utility in integral imaging and 3D displays1,2,3, synthetic aperture imaging4, endoscopes5, plenoptic cameras6 and solar concentrators7. Dynamically switchable reflective micro-optics based on digital micro-mirror displays8 and continuously reconfigurable absorptive pixel technology enabled by liquid crystal displays9 have greatly enhanced the versatility of micro-optics. These methods have enabled transformative advances in optical technology ranging from high-resolution displays to structured illumination microscopy, holographic optical tweezers and wavefront-shapers10,11.
Morphological reconfiguration of micro-scale refractive components to enhance optical performance has recently been observed in the context of biological vision systems: rod photoreceptor cell nuclei in the retina of nocturnal mammals specifically adapt a bi-phase refractive index distribution to act as collecting lenses. These biological micro-lenses channel light towards the rods' light sensing segments, thereby increasing the signal to noise ratio of retinal transmitted images12,13. Similarly, man-made, refractive micro-elements with reconfigurable morphology, enabling in-situ tunable optical properties are poised to complement and extend the capabilities of present micro-optical devices14,15,16,17. In particular, tunable micro-lens designs employed as responsive in-line, phase-modulating, intensity-preserving components will extend the light manipulation capabilities of optical systems10.
To this end, optofluidic devices using dynamic fluid lens materials represent an ideal platform to create versatile, reconfigurable, refractive optical components17,18. Droplets smaller than the capillary length, wherein surface tension is the dominant force, create curved interfaces between fluid volumes19 and display intrinsic lensing behaviour. In addition, liquids have minimal surface roughness on the order of nanometres, even if the interfacial tension is very low20,21. Dynamic lensing materials based on hydrogels and liquids can be reshaped through various external stimuli after the optical element is formed, which is ideal for adaptive optics, imaging devices or sensors14,22,23,24. For example, reconfigurable liquid lenses have been demonstrated by taking advantage of electro-wetting25,26,27,28,29,30,31,32 and the integration of microfluidics with MEMS technology16. Adjustable focal length lenses were realized using microfluidics, by varying the amount of liquid in a reservoir behind an elastic membrane22,33,34,35,36,37. Alternatively, the controlled flow of liquids within microfluidic channels can be used to create micro-lenses with variable focus38,39. Micrometre-sized solid-liquid doublet lenses that allow for minimization of optical aberrations have also been fabricated33. Tunable fluid micro-lenses, as individual components or arranged in arrays, have found applications in miniaturized optical components with variable working distances and optics-based biosensing devices40,41. Incorporation of dyes into the liquids allows for droplets that serve as both lenses and optical filters42. In particular, the incorporation of laser dyes in micro-fluidic droplets enables lasing-based sensing approaches with high sensitivity and throughput43.
We present herein the optical characteristics of a new generation of fluidic tunable compound micro-lenses. These compound micro-lenses are composed of hydrocarbon and fluorocarbon liquids that form stable bi-phase emulsion droplets in aqueous media44. The choice of constituent liquids can dramatically impact the optical properties. In this initial study, we focus on combinations of transparent fluids Fluorinert FC-770 with heptane , or hexane . The refractive index of the hydrocarbon constituent is higher than the refractive index of water , while the fluorinated component has a refractive index lower than that of water. The refractive index contrast at each material interface as well as the curvature of each interface contributes to the focusing power of a refractive optical element (see lens maker's equation45). Therefore, we anticipated that these fluid combinations could allow for a wide tuning range of the emulsion lenses' focal length, thereby enabling switching between converging or diverging lens geometries. The complex droplet lenses can be easily fabricated on a large scale using a temperature-induced phase separation technique appropriate for combinations of liquids having a relatively low upper critical solution temperature46. Most importantly, such complex droplets can be dynamically reconfigured between double emulsion and Janus (two-sided) morphologies through application of external stimuli, which makes these droplets very promising as highly tunable compound lenses. We demonstrate the adjustability in focal length of the lenses as well as their microscopic and macroscopic light manipulation characteristics.
Results
Modelling of emulsion droplets as tunable lenses
For these particular emulsions, the curvature of the internal interface formed between the immiscible phases can be adjusted using surfactants that modify the relative interfacial tensions between the droplet phases and water. Surfactant-mediated modification of interfacial tensions results in a variation of the contact angles at the triple-phase contact line. This determines the radius of curvature of the lenses' internal interface, which in turn affects the optical properties of the droplets (Fig. 1a,b). To demonstrate how the controlled, dynamic variation of the complex droplets' geometry could induce a tunable interaction with light, a ray-tracing algorithm was implemented in MATLAB. The overall droplet shape was assumed to be spherical, which is an appropriate approximation when the interfacial tension between the droplet phases is much smaller than the interfacial tensions between the droplet constituents and the aqueous medium (Fig. 1a) (ref. 47). This is the case for working temperatures close to the critical temperature of the internal fluids. For the droplet diameters on the order of 100 μm discussed here, the internal interface can be considered to be spherical, since the ratio of gravitational to surface tension forces is small (see discussion in Methods). Under these assumptions, the distance l of the interface from the centre of the overall drop is given by
Figure 1: Concept and modelling of microfluidic emulsion-based compound lenses.
Figure 1
(a) Geometry of a bi-phase emulsion droplet. The internal curvature Ri is determined by the interfacial tensions between hydrocarbon and water γH, fluorocarbon and water γF, and hydro- and fluorocarbon γFH. The distance from the centre of the drop to the internal interface l is constrained by the volume ratio (equation (1)). (b) Double emulsions are expected to switch between focusing and diverging geometries. (c) Side view optical micrographs of droplets composed of FC-770 (grey) and heptane (red) with varying internal interface curvature. The red colour of the heptane phase results from the incorporation of the dye Sudan Red 7B. (d) Corresponding ray-tracing simulations showing the propagation of light rays through the droplets.
where Rd is the radius of the drop, Ri is the internal radius of curvature and vr is the volume ratio of the internal droplet phase to the outer droplet phase. The internal curvature is set by the balance of interfacial tensions at the triple-phase contact line47 given by
The derivation of equations (1) and (2) can be found in Supplementary Note 1.
When the optical axis is aligned with the droplets' symmetry axis, the optical system is axisymmetric and can be modelled in two dimensions. The droplets' symmetry axis aligns with the gravitational field due to the difference in density between the light hydrocarbon phase and the dense fluorocarbon phase. We exploit this alignment in our theoretical and experimental study of the droplets' optical characteristics. The ray-tracing calculations predict that the double emulsion droplets with a high refractive index core phase and a lower refractive index shell phase can focus light, while an inversion of this droplet geometry results in diverging lenses (Fig. 1c,d). By adjusting the droplets' internal interface curvature, each droplet can be tuned between a converging lens with varying positive optical power and a diverging lens with varying negative optical power. This optical behaviour is similar to the characteristic differences observed for the retina cell nuclei of nocturnal and diurnal mammals. Photoreceptor nuclei of nocturnal mammals concentrate on the highly refractive heterochromatin in the nuclear centre, while diurnal mammalian retina cells locate heterochromatin material towards their periphery12. The nucleus geometry with the higher refractive index material concentrated at the nucleus