Compact spectrum splitting photovoltaic module with high efficiency

We have designed, fabricated, and tested a small, integrated photovoltaic module comprised of two separately‐contacted, high efficiency, multijunction solar cells and non‐imaging optics that both concentrate and spectrally split the incoming light. This hybrid design allows us to individually optimize the tandem cells and optical elements. The system has a measured module efficiency, including optical and packaging losses but not power combination losses, of 38.5 ± 1.9% under the AM1.5 direct terrestrial spectrum. The internal optics concentrate the light by a factor of approximately 20. We find excellent agreement between the modeled and measured performance. This is the highest confirmed conversion efficiency demonstrated for a photovoltaic module. Copyright © 2010 John Wiley & Sons, Ltd.     

高级时装

随着一大批富有探索精神的设计师日益占据时装周的日程表,传统的高级时装圈正面临天翻地覆的震荡。这究竟是对纯正的高级时装工艺的曲解,抑或是一个正确的发展方向?也许,唯有时间和极少数顶尖高级时装客户的评价才能给出最终的答案。     

男装高级成衣

从艳丽到朴素,从廓形刺激到舒适触感,本季的男装非常强势却不会太过冒险。奢侈品始终是小众需求,更多的是以可承受的价格巧妙地体现出奢华。大胆的几何感非常抢眼,但保持基本的廓形很重要,因为这样能够降低风险——大部分款式并不复杂,而是低调和可理解的。这是个视觉化的季节,同时也是个非常实用,把功能性考虑在先的季节。     

男装高级成衣

庄严肃穆更加成熟的男装设计:风格统一的舒适单品营造出严肃稳重的整体氛围。商业化设计的严肃正装,高贵威严的同时仍不失时尚锋芒。本季的男装设计涵盖了所有必须的时尚元素,而这些元素同时构成了高度商业化的产品,从席卷而来的绵羊革风潮到黑色设计的海啸……本季设计更以惊人的材质展现出新奇的想象和无限的创意。庄重看似庄重的造型却不失其独特个性和青春活力。自信、纯粹,还带有一丝沉静。色彩:黑色作为渴求无限可能的象征成为这一风格的催化剂。面料:唯有高品质帆布面料搭配最为纯粹的黑色才能最大限度地展示这     

Temperature-dependent electrical resistance of conductive polylactic acid filament for fused deposition modeling

This study characterizes the microstructure and temperature dependence of resistance of two commercially available electrically conductive polylactic acid (PLA) composites for fused deposition modeling (FDM): PLA-carbon black and PLA-graphene. No microstructural changes were observed between the filament and the printed parts; however, the resistivity of the filament was found to drop by four to six times upon FDM. Also, compared to the resistivity of individual extruded wire, the resistivity of the printed parts was found to be up to 1500 times higher for PLA-graphene and up to 300 times higher for PLA-carbon black. The raw PLA-carbon black filament and printed wire showed a positive temperature coefficient of resistance (α) value between ~?0.03 and 0.01 °C^?1, which makes them more suitable for sensor development. The raw PLA-graphene filament and printed wire did not exhibit a significant α, which makes them more suitable for printing wires. However, the parts made with multilayer FDM exhibited a negative or a negligible α up to a certain temperature prior to exhibiting a positive α; further, these α values were significantly lower than those obtained for the filaments before or after extrusion. These findings enable proper selection of commercial conductive FDM filaments for enabling quicker prototyping of electronics and sensors.     

Unbiased linear property estimation for spheres,from sections exhibiting overprojection and truncation

In the biological sciences, stereological techniques are frequently used to infer changes in structural parameters (volume fraction, for example) between samples from different populations or subject to differing treatment regimes. Non-homogeneity of these parameters is virtually guaranteed, both between experimental animals and within the organ under consideration. A two-stage strategy is then desirable, the first stage involving unbiased estimation of the required parameter, separately for each experimental unit, the latter being defined as a subset of the organ for which homogeneity can reasonably be assumed. In the second stage, these point estimates are used as data inputs to a hierarchical analysis of variance, to distinguish treatment effects from variability between animals, for example. Techniques are therefore required for unbiased estimation of parameters from potentially small numbers of sample profiles. This paper derives unbiased estimates of linear properties in one special case—the sampling of spherical particles by transmission microscopy, when the section thickness is not negligible and the resulting circular profiles are subject to lower truncation. The derivation uses the general integral equation formulation of Nicholson (1970); the resulting formulae are simplified, algebraically, and their efficient computation discussed. Bias arising from variability in slice thickness is shown to be negligible in typical cases. The strategy is illustrated for data examining the effects, on the secondary lysosomes in the digestive cells, of exposure of the common mussel to hydrocarbons. Prolonged exposure, at 30 μg 1^?1 total oil-derived hydrocarbons, is seen to increase the average volume of a lysosome, and the volume fraction that lysosomes occupy, but to reduce their number.     

Holographic interferometers with photorefractive recording media

We discuss two types of holographic interferometer that contain photorefractive recording media. The first type contains two beams interacting in a photorefractive medium. The second type utilizes a single beam and relies on self-pumped phase conjugation from a photorefractive crystal to make phase changes appear as intensity changes. We show both theoretically and experimentally that the first type can be analyzed in a straightforward manner; however, the second type cannot be approximated as simply a special case of the first type, as one may n?ively suspect.