Xem 1-20 trên 21 kết quả Led characteristics
  • First off, it’s all about the lumens. Lumens are the visible light given off by a source, and they are the ultimate goal. Wattage has often been confused with lumens, thanks to how incandescent bulbs are rated (everyone knows that a 60W bulb is not as bright as a 100W one), but more efficient lighting technologies have greatly changed the relationship between wattage (essentially power usage) and lumens (light output). For example, an incandescent might operate at about 12-15 lumens-per-watt (lm/W), while an LED bulb will be in the range of 40-50, a much greater luminous efficacy...

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  • Introduction to LEDs: How LEDs work + some points. Comparison with other sources of light. LED in communication. Blue &White LED technologies. How they are made? Their application? Brief about blue laser? Stands for light emitting diode. Semiconductor device: p-n junction forward-biased.current emits incoherent narrow spectrum light (due to recombination in transition region near the junction.) Color of the emitted light depends on the chemical of the semiconducting material used. (Near-ultraviolet, visible or infrared.)...

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  • The wide geographical distribution of the rice plant ( Oryza sativa L.) and its long history of cultivation in Asian countries have led to the development of a great diversity of varietal types. Similarly, workers in various rice-growing countries use different terms to designate identical morphological and physiological characters, agronomic traits, gene symbols, and cultural practices. Whereas varietal diversity in germ plasm is desired in rice breeding, variations in nomenclature hinder scientific communication among the workers.

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  • Light sources should be as small as possible, produce light efficiently and have a long life. The demands of architects, light planners and operators of lighting installations have formed the basis of the research and development work of the lighting industry. Today more light sources with these properties are on the market than ever before in the history of artificial light. Until now, however, no filament or discharge lamp has combined all three properties. Only light emitting diodes (LEDs), also called light diodes, achieve this.

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  • The 2007–08 boom in food prices and the subsequent period of relatively high and volatile prices reminded many import-dependent countries of their vul- nerability to food insecurity and prompted them to seek opportunities to secure food supplies overseas. Together with the reduced attractiveness of other assets due to the financial crisis, the boom led to a “rediscovery” of the agricultural sector by different types of investors and a wave of interest in land acquisitions in developing countries.

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  • The study that led to this report was called for in the President’s Fiscal Year 2006 Budget. In accordance with that call, the study was commissioned by the National Coordination Office (NCO) for Networking and Information Technology Research and Development (NITRD), which supports the NITRD Subcommittee, which operates under the White House National Science and Technology Council to coordinate federal investments in networking and information technology research and development.

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  • Banks thus planned to meet their shortfalls predominantly through capital measures, and some made progress in spite of unfavourable market conditions. Low share prices, as at present, cause a strong dilution effect, drawing resistance from incumbent shareholders and management. 4 The experience of UniCredit, whose deeply discounted €7.5 billion rights issue led to a 45% (albeit transient) plunge in its share price, deterred other banks from following suit. Capital can also be built through retained earnings, debt-to- equity conversion or redemption below par.

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  • Introduction: The rapid growth of the miniature electronic and computer-related industries has led to great demand for smaller and lighter batteries with improved safety, energy, and power characteristics. Lithium polymer batteries are expected to meet the above requirements and are thus considered as next-generation rechargeable batteries. The conventional lithium-ion batteries, which contain a large amount of liquid electrolyte, emit an appreciable amount of gas and this is attributed to the decomposition of a protective layer at the carbon surface. ...

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  • Optical Fibers The phenomenon of total internal reflection, responsible for guiding of light in optical fibers, has been known since 1854 [1]. Although glass fibers were made in the 1920s [2]–[4], their use became practical only in the 1950s, when the use of a cladding layer led to considerable improvement in their guiding characteristics [5]–[7]. Before 1970, optical fibers were used mainly for medical imaging over short distances [8]. Their use for communication purposes was considered impractical because of high losses (∼ 1000 dB/km).

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  • The importance of particle characterization in both the research and development, and the manufacture and quality control of materials and products that we use in our everyday lives is, in some sense, invisible to those of us not directly involved with these activities. Few of us know how particle size, shape, or surface characteristics can influence, for example, the efficacy of a painreliever, or the efficiency of a catalytic converter, or the resolution of a printer.

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  • Middle-Period Infections Because of continuing immunosuppression, kidney transplant recipients are predisposed to lung infections characteristic of those in patients with T cell deficiency (i.e., infections with intracellular bacteria, mycobacteria, nocardiae, fungi, viruses, and parasites). The high mortality rates associated with Legionella pneumophila infection (Chap. 141) led to the closing of renal transplant units in hospitals with endemic legionellosis.

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  • The invention of scanning tunneling microscope (STM) by Binnig and his colleagues in 1982 opened up the possibility of imaging material surfaces with spatial resolution much superior to the conventional microscopy techniques. The STM is the first instrument capable of directly obtaining three-dimensional images of solid surfaces with atomic resolution. Even though STM is capable of achieving atomic resolution, it can only be used on electrical conductors. This limitation has led to the invention of atomic force microscope (AFM) by Binnig and his co-workers in 1986.

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  • Spatial or territorial organization is one of effective tools for sustainable land use. Spatial organization of land use and environmental protection by functional sub-areas is performed on the basis of comprehensive and integrated research on characteristics and differentiation laws of natural components and landscapes, socio-economic factors, the present status and trend of environmental changes as well as the structures and functions of sub-areas. Uong Bi is a national center for tourism, coal mining and thermal power production.

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  • While specific information on the DOD protocols is fairly generally available’, 6. ‘, it is sometimes difficult to determine the motivation and reasoning which led to the design. In fact, the design philosophy has evolved considerably from the first proposal to the current standards. For example, the idea of the datagram, or connectionless service, does not receive particular emphasis in the first paper, but has come to be the defining characteristic of the protocol. Another example is the layering of the architecture into the IP and TCP layers.

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  • Closer to home, PassivSystem’s Chief Executive Officer and founder Colin Calder got the idea for his company when he tried to build a zero-carbon footprint house in Tuscany and discovered that none of the green energy systems he wanted to use were compatible with each other. Calder immediately saw the incompatibility as a business opportunity. The experience led him to design a networked control system relying on internal and external sensors that synchronizes the different sources of energy entering a house in order to get the maximum efficiency at the lowest cost.

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  • This charge was extremely broad. It could have included literature reviews on such topics as characteristics of substance users, etiology of initiation of use, etiology of dependence, drug use prevention programs, and drug treatments. Two considerations led to narrowing the focus of our work. The first was substantive. Each of the topics just noted involves very large fields of

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  • This publication presents agronomic reasons which have led to the development of controlled-release and stabilized fertilizers. The characteristics, the advantages and the possible disadvantages of controlled-release and nitrification/urease inhibitors are discussed. Particular attention is given to problems of legislation, registration, methodology and standardization. Leading manufacturers and their product ranges are listed.

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  • Several transcription factors with the function of setting the biological clock in vertebrates have been described. A detailed understanding of their nucleocytolasmic transport properties may uncover novel aspects of the regulation of the circadian rhythm. This assumption led us to perform a systematic analysis of the nuclear import characteristics of the different murine PER and CRY proteins, usingXenopusoocytes and HeLa cells as experimental systems.

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  • The Nipah and Hendra viruses are highly pathogenic paramyxoviruses that recently emerged from flying foxes to cause serious disease outbreaks in humans and livestock in Australia, Malaysia, Singapore and Bangladesh. Their unique genetic constitution, high virulence and wide host range set them apart from other paramyxoviruses. These characteristics have led to their classification into the new genus Henpaviruswithin the family Para-myxoviridae and to their designation as Biosafety Level 4 pathogens. ...

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  • Research on the text generation task has led to creation of a large systemic grammar of English, Nigel, which is embedded in a computer program. The grammar and the systemic framework have been extended by addition of a semantic stratum. The grammar generates sentences and other units under several kinds of experimental control. This paper describes augmentations of various precedents in the systemic framework. The emphasis is on developments which control the text to fulfill a purpose, and on characteristics which make Nigel relatively easy to embed in a larger experimental program. ...

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