• Problem Management Tools Summary. This information is now obsolete and is retained online only for archival purposes. Introduction This was the newsgroup comp.
• The Open Source Initiative's (OSI) definition is recognized by governments internationally as the standard or de facto definition. In addition, many of the world's.
• Advantages It means all of the information is together. The information can be portable if on a laptop.

OLED - Wikipedia. Prototype OLED lighting panels. An organic light- emitting diode (OLED) is a light- emitting diode (LED) in which the emissiveelectroluminescent layer is a film of organic compound that emits light in response to an electric current. This layer of organic semiconductor is situated between two electrodes; typically, at least one of these electrodes is transparent. OLEDs are used to create digital displays in devices such as television screens, computer monitors, portable systems such as mobile phones, handheld game consoles and PDAs.

A major area of research is the development of white OLED devices for use in solid- state lighting applications. Adding mobile ions to an OLED creates a light- emitting electrochemical cell (LEC) which has a slightly different mode of operation. An OLED display can be driven with a passive- matrix (PMOLED) or active- matrix (AMOLED) control scheme. In the PMOLED scheme, each row (and line) in the display is controlled sequentially, one by one. In low ambient light conditions (such as a dark room), an OLED screen can achieve a higher contrast ratio than an LCD, regardless of whether the LCD uses cold cathode fluorescent lamps or an LED backlight.

History. They applied high alternating voltages in air to materials such as acridine orange, either deposited on or dissolved in cellulose or cellophane thin films. The proposed mechanism was either direct excitation of the dye molecules or excitation of electrons. These contacts are the basis of charge injection in all modern OLED devices. Pope's group also first observed direct current (DC) electroluminescence under vacuum on a single pure crystal of anthracene and on anthracene crystals doped with tetracene in 1.

One advantage to using a proprietary-software system is that you will generally be able to take advantage of the software company's customer service.

The proposed mechanism was field- accelerated electron excitation of molecular fluorescence. Pope's group reported in 1. Also in 1. 96. 5, W. Helfrich and W. Schneider of the National Research Council in Canada produced double injection recombination electroluminescence for the first time in an anthracene single crystal using hole and electron injecting electrodes. In the same year, Dow Chemical researchers patented a method of preparing electroluminescent cells using high- voltage (5.

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V) AC- driven (1. Hz) electrically insulated one millimetre thin layers of a melted phosphor consisting of ground anthracene powder, tetracene, and graphite powder. The device consisted of a film of poly(N- vinylcarbazole) up to 2. The results of the project were patented in 1.

Tang and his co- worker Steven Van Slyke at Eastman Kodak built the first practical OLED device in 1. Burroughes et al. Emissive Layer, 3. Emission of radiation, 4. Conductive Layer, 5. Anode (+)A typical OLED is composed of a layer of organic materials situated between two electrodes, the anode and cathode, all deposited on a substrate.

The organic molecules are electrically conductive as a result of delocalization of pi electrons caused by conjugation over part or all of the molecule. These materials have conductivity levels ranging from insulators to conductors, and are therefore considered organic semiconductors.

The highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) of organic semiconductors are analogous to the valence and conduction bands of inorganic semiconductors. One example was the first light- emitting device synthesised by J. Burroughes et al., which involved a single layer of poly(p- phenylene vinylene). However multilayer OLEDs can be fabricated with two or more layers in order to improve device efficiency. As well as conductive properties, different materials may be chosen to aid charge injection at electrodes by providing a more gradual electronic profile.

More recent developments in OLED architecture improves quantum efficiency (up to 1. The graded heterojunction architecture combines the benefits of both conventional architectures by improving charge injection while simultaneously balancing charge transport within the emissive region. Anodes are picked based upon the quality of their optical transparency, electrical conductivity, and chemical stability.

This latter process may also be described as the injection of electron holes into the HOMO. Electrostatic forces bring the electrons and the holes towards each other and they recombine forming an exciton, a bound state of the electron and hole. This happens closer to the emissive layer, because in organic semiconductors holes are generally more mobile than electrons. The decay of this excited state results in a relaxation of the energy levels of the electron, accompanied by emission of radiation whose frequency is in the visible region. The frequency of this radiation depends on the band gap of the material, in this case the difference in energy between the HOMO and LUMO. As electrons and holes are fermions with half integer spin, an exciton may either be in a singlet state or a triplet state depending on how the spins of the electron and hole have been combined. Statistically three triplet excitons will be formed for each singlet exciton.

Decay from triplet states (phosphorescence) is spin forbidden, increasing the timescale of the transition and limiting the internal efficiency of fluorescent devices. Phosphorescent organic light- emitting diodes make use of spin–orbit interactions to facilitate intersystem crossing between singlet and triplet states, thus obtaining emission from both singlet and triplet states and improving the internal efficiency. Indium tin oxide (ITO) is commonly used as the anode material. It is transparent to visible light and has a high work function which promotes injection of holes into the HOMO level of the organic layer. A typical conductive layer may consist of PEDOT: PSS. Metals such as barium and calcium are often used for the cathode as they have low work functions which promote injection of electrons into the LUMO of the organic layer. Imperfections in the surface of the anode decrease anode- organic film interface adhesion, increase electrical resistance, and allow for more frequent formation of non- emissive dark spots in the OLED material adversely affecting lifetime.

Mechanisms to decrease anode roughness for ITO/glass substrates include the use of thin films and self- assembled monolayers. Also, alternative substrates and anode materials are being considered to increase OLED performance and lifetime.

Possible examples include single crystal sapphire substrates treated with gold (Au) film anodes yielding lower work functions, operating voltages, electrical resistance values, and increasing lifetime of OLEDs. As current through the device is composed of only one type of charge carrier, either electrons or holes, recombination does not occur and no light is emitted. For example, electron only devices can be obtained by replacing ITO with a lower work function metal which increases the energy barrier of hole injection. Similarly, hole only devices can be made by using a cathode made solely of aluminium, resulting in an energy barrier too large for efficient electron injection. A common way to balance charge is optimizing the thickness of the charge transporting layers but is hard to control. Another way is using the exciplex.

Exciplex formed between hole- transporting (p- type) and electron- transporting (n- type) side chains to localize electron- hole pairs. Energy is then transferred to luminophore and provide high efficiency. An example of using exciplex is grafting Oxadiazole and carbazole side units in red diketopyrrolopyrrole- doped Copolymer main chain shows improved external quantum efficiency and color purity in no optimized OLED. The term OLED traditionally refers specifically to this type of device, though the term SM- OLED is also in use. A number of materials are used for their charge transport properties, for example triphenylamine and derivatives are commonly used as materials for hole transport layers.

Open- source software - Wikipedia. Open- source software (OSS) is computer software with its source code made available with a license in which the copyright holder provides the rights to study, change, and distribute the software to anyone and for any purpose. According to scientists who studied it, open- source software is a prominent example of open collaboration.

A 2. 00. 8 report by the Standish Group states that adoption of open- source software models has resulted in savings of about $6. Eventually the open source notion moved to the way side of commercialization of software in the years 1. In 1. 99. 7, Eric Raymond published The Cathedral and the Bazaar, a reflective analysis of the hacker community and free software principles. The paper received significant attention in early 1. Netscape Communications Corporation to release their popular Netscape Communicator Internet suite as free software.

This source code subsequently became the basis behind Sea. Monkey, Mozilla Firefox, Thunderbird and Kompo.

Zer. Netscape's act prompted Raymond and others to look into how to bring the Free Software Foundation's free software ideas and perceived benefits to the commercial software industry. They concluded that FSF's social activism was not appealing to companies like Netscape, and looked for a way to rebrand the free software movement to emphasize the business potential of sharing and collaborating on software source code. The Open Source Initiative was founded in February 1. A Microsoft executive publicly stated in 2. I can't imagine something that could be worse than this for the software business and the intellectual- property business. IBM, Oracle, Google and State Farm are just a few of the companies with a serious public stake in today's competitive open- source market.

There has been a significant shift in the corporate philosophy concerning the development of FOSS. In 1. 99. 8, a group of individuals advocated that the term free software should be replaced by open- source software (OSS) as an expression which is less ambiguous. With open- source software, generally anyone is allowed to create modifications of it, port it to new operating systems and instruction set architectures, share it with others or, in some cases, market it. Scholars Casson and Ryan have pointed out several policy- based reasons for adoption of open source – in particular, the heightened value proposition from open source (when compared to most proprietary formats) in the following categories: Security. Affordability. Transparency.

Perpetuity. Interoperability. Flexibility. Localization—particularly in the context of local governments (who make software decisions).

Casson and Ryan argue that . Software licenses grant rights to users which would otherwise be reserved by copyright law to the copyright holder. Several open- source software licenses have qualified within the boundaries of the Open Source Definition. The most prominent and popular example is the GNU General Public License (GPL), which . A group of individuals at the session included Tim O'Reilly, Linus Torvalds, Tom Paquin, Jamie Zawinski, Larry Wall, Brian Behlendorf, Sameer Parekh, Eric Allman, Greg Olson, Paul Vixie, John Ousterhout, Guido van Rossum, Philip Zimmermann, John Gilmore and Eric S.

Since a great deal of free software already was (and still is) free of charge, such free software became associated with zero cost, which seemed anti- commercial. With at least 2. 0 years of evidence from case histories of closed software development versus open development already provided by the Internet developer community, the OSI presented the . The OSI hoped that the use of the label . At The Feet Of The Master Jiddu Krishnamurti more. They sought to bring a higher profile to the practical benefits of freely available source code, and they wanted to bring major software businesses and other high- tech industries into open source.

Perens attempted to register . Meanwhile, due to the presentation of Raymond's paper to the upper management at Netscape—Raymond only discovered when he read the Press Release.

In addition, many of the world's largest open source software projects and contributors, including Debian, Drupal Association, Free. BSD Foundation, Linux Foundation, Mozilla Foundation, Wikimedia Foundation, Wordpress Foundation have committed.

The definition was based on the Debian Free Software Guidelines, written and adapted primarily by Perens. It is an explicit . Although he agrees that the two terms describe . Some open- source projects do not take contributed code under a license, but actually require joint assignment of the author's copyright in order to accept code contributions into the project. With more than 1.

Some are home- grown, while others are modeled after mainstream FOSS licenses such as Berkeley Software Distribution (. In view of this, open- source practitioners are starting to use classification schemes in which FOSS licenses are grouped (typically based on the existence and obligations imposed by the copyleft provision; the strength of the copyleft provision). As a result, if end- users violate the licensing conditions, their license disappears, meaning they are infringing copyright.

Certification could be applied to the simplest component, to a whole software system. The United Nations University International Institute for Software Technology. This project aims to build a desktop interface that every end- user is able to understand and interact with, thus crossing the language and cultural barriers. The project would improve developing nations' access to information systems.

UNU/IIST hopes to achieve this without any compromise in the quality of the software by introducing certifications. Raymond suggests a model for developing OSS known as the bazaar model. Raymond likens the development of software by traditional methodologies to building a cathedral, . Roles are clearly defined. Roles include people dedicated to designing (the architects), people responsible for managing the project, and people responsible for implementation. Traditional software engineering follows the cathedral model. The bazaar model, however, is different.

In this model, roles are not clearly defined. Gregorio Robles. Furthermore, users are encouraged to submit additions to the software, code fixes for the software, bug reports, documentation etc. Having more co- developers increases the rate at which the software evolves. Linus's law states, . Note that some users have advanced programming skills, and furthermore, each user's machine provides an additional testing environment. This new testing environment offers that ability to find and fix a new bug. Early releases. The first version of the software should be released as early as possible so as to increase one's chances of finding co- developers early.

Frequent integration. Code changes should be integrated (merged into a shared code base) as often as possible so as to avoid the overhead of fixing a large number of bugs at the end of the project life cycle. Some open source projects have nightly builds where integration is done automatically on a daily basis. Several versions.

There should be at least two versions of the software. There should be a buggier version with more features and a more stable version with fewer features. The buggy version (also called the development version) is for users who want the immediate use of the latest features, and are willing to accept the risk of using code that is not yet thoroughly tested. The users can then act as co- developers, reporting bugs and providing bug fixes. High modularization. The general structure of the software should be modular allowing for parallel development on independent components.

Dynamic decision making structure. There is a need for a decision making structure, whether formal or informal, that makes strategic decisions depending on changing user requirements and other factors. Extreme programming. Data suggests, however, that OSS is not quite as democratic as the bazaar model suggests.