SHORT COMMUNICATION: Solar cell efficiency tables (version 25)

Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined and new entries since June 2004 are reviewed. Copyright © 2005 John Wiley & Sons, Ltd.     

现代通信测试设备必须适合多种手机标准--谈如何选择射频功率分析测试仪器

在通信设备生产领域，射频功率的测量是必不可少的。主信道的功率测量往往决定了接通的质量，邻信道的功率测量则决定不同手机用户之间的干扰程度。而所有上述的指标必须符合相应的工业标准。例如，cdmaOne的手机标准清楚定义了频谱相对于载频的最大干扰度，并指明了有关射频功率测试的详细办法。单纯的功率表往往不能提供与频谱相关的测试功能，因为其不能分辨总功率下的不同子功率，也不能分辨被测发射带宽区域内外的频率。但是，单纯的功率表较为便宜，价格一般为5000美金左右，这对于那些在生产过程中只测量总输出功率的用户来说是符合…     

PMD and PDL monitoring of traffic-carrying transatlantic fibre-optic system

For the first time the direct monitoring of polarisation mode dispersion (PMD) and polarisation-dependent loss (PDL) in a traffic-carrying transatlantic fibre-optic system without the requirement of loopingback is reported. The impact of transmitter polarisation scrambling in the measured results is analysed and verified by the measured results.     

Fault and attack management in all-optical networks

Network management for optical networks faces additional security challenges that arise by using transparent optical network components in communication systems. While some available management mechanisms are applicable to different types of network architectures, many of these are not adequate for all-optical networks. These have unique features and requirements in terms of security and quality of service, thus requiring a much more targeted approach in terms of network management. In this article we consider management issues with particular emphasis on complications that arise due to the unique characteristics and peculiar behaviors of transparent network components. In particular, signal quality monitoring is still a major complication in all-optical networks. Despite new methods for detection and localization of attacks having been proposed, no robust standards or techniques exist to date for guaranteeing the quality of service in these networks. Therefore, sophisticated mechanisms that assist in managing and assessing the proper function of transparent network components are highly desirable. Accordingly, we present an algorithm for multiple attack localization and identification that can participate in some tasks for fault management of all-optical networks     

Top management support of R&D projects: a strategic leadershipperspective

A study of top management support of 213 R&D projects in 21 major firms revealed significant relationships between independent informants' perceptions of top management support, project characteristics, and project performance. Testing a model based on a strategic leadership perspective, top management support was found to be directed at certain types of projects, i.e., those that were expected to make greater contributions to business goals, represented larger investments, were seeking new products and process versus incremental improvements, and had originated from business sources as opposed to R&D. In addition, even after controlling for these project characteristics, projects with top management support were less likely to be terminated. In contrast, after controlling for project characteristics, completed projects with top management support were not judged to make greater contributions to the firm's business goals suggesting top management may not be able to pick winners. Findings are discussed in terms of future research and implications for top management leadership within R&D     

Solar cell efficiency tables (Version 31)

Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined and new entries since July, 2008 are reviewed. Copyright © 2007 John Wiley & Sons, Ltd.     

Radiative efficiency of state‐of‐the‐art photovoltaic cells

Maximum possible photovoltaic performance is reached when solar cells are 100% radiatively efficient, with different photovoltaic technologies at different stages in their evolution towards this ideal. An external radiative efficiency is defined, which can be unambiguously determined from standard cell efficiency measurements. Comparisons between state‐of‐the‐art devices from the representative cell technologies produce some interesting conclusions. Copyright © 2011 John Wiley & Sons, Ltd.     

Solar cell efficiency tables (version 43)

Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined, and new entries since July 2013 are reviewed. Copyright © 2013 John Wiley & Sons, Ltd.     

Dynamic laser control using feedback from a gain grating

We demonstrate that self-induced gain gratings can provide nonlinear optical feedback that results in single frequency selection and passive self Q-switching of a conventional linear laser cavity. An experimental Nd:YAG laser system is described that yields a temporally-smooth 20 ns pulse at 1.064 μm. In addition, we show that the feedback has phase-conjugate properties that permit “flower-like” mode formation even though the azimuthal symmetry of the cavity is broken     

Performance characteristics of a compact position-sensitive LSO detector module

We assembled a compact detector module comprised of an array of small, individual crystals of lutetium oxyorthosilicate:Ce (LSO) coupled directly to a miniature, metal-can, position-sensitive photomultiplier tube (PSPMT). We exposed this module to sources of 511-keV annihilation radiation and beams of 30- and 140-keV photons and measured spatial linearity; spatial variations in module gain, energy resolution, and event positioning; coincidence timing; the accuracy and sensitivity of identifying the crystal-of-first-interaction at 511 keV; and the effects of intercrystal scatter and LSO background radioactivity. The results suggest that this scintillator/phototube combination should be highly effective in the coincidence mode and can be used, with some limitations, to image relatively low-energy single photon emitters. Photons that are completely absorbed on their first interaction at 511 keV are positioned by the module at the center of a crystal. Intercrystal scatter events, even those that lead to total absorption of the incident photon, are placed by the module in a regular "connect-the-dot" pattern that joins crystal centers. As a result, the accuracy of event positioning can be made to exceed 90%, though at significantly reduced sensitivity, by retaining only events that occur within small regions-of-interest around each crystal center and rejecting events that occur outside these regions in the connect-the-dot pattern.