Nanoscale(纳米)材料制造超薄偏光薄膜

Optiva开发了一种使用自聚合纳米材料的处理技术,可以制造薄型晶体薄膜偏光器,并且可以将亚微米的图形直接印刷到玻璃或者塑料上,可以制造更薄而简单的LCD。传统的LCD制造使用200μm的偏光薄膜,这种技术具有75年的历史,容易导致设备厚度和成本的增加。 除了减少了层次和降低了复杂性外,TCF偏光器比传统的偏光器降低了光泄漏,具有更高的稳定性和更宽的视角,提高了LCD的性能。TCF材料的另一个优势就是可以经受200℃的高温,而传统的偏光器只能承受低于90℃的温度。     

Annual performance enhancement of building integrated photovoltaic modules by applying phase change materials

The performance of photovoltaic (PV) module outdoors suffers from attained high module temperatures due to irradiation as a result of the negative temperature coefficient of their efficiency. Phase change materials (PCMs) are investigated as an option to regulate photovoltaic module temperature and thereby reduce its electrical efficiency decrease. In this study, a simplified heat balance model is used to calculate the extra energy gain; such a PV/PCM system can bring on an annual basis. With present day commercially available PCM materials, a moderate increase of up to 3% of the total energy output can be expected. When taking into account the additional PCM material cost, a PV/PCM module presently is not economically viable. For an acceptable payback period of 10–20 years to be reached, the heat storage capacity of a PCM would require an increase of about one order of magnitude, which is presently not realistic. Nevertheless, a combination with building climate control in which the PCM plays a double role controlling both the PV temperature as well as the inside climate temperature may be feasible. Copyright © 2011 John Wiley & Sons, Ltd.     

相变材料在弹载电子设备热设计中的应用

弹载环境下,重量受到较大的限制.对于大热耗的电子设备,仅仅依靠金属结构件,不能满足工作时间内蓄热要求.通过在金属结构件中填充相变材料,在不增加系统重量的前提下,可以极大的提高系统的蓄热能力,从而满足系统蓄热要求.     

A novel hybrid heat sink using phase change materials for transient thermal management of electronics

A hybrid heat sink concept which combines passive and active cooling approaches is proposed. The hybrid heat sink is essentially a plate fin heat sink with the tip immersed in a phase change material (PCM). The exposed area of the fins dissipates heat during periods when high convective cooling is available. When the air cooling is reduced, the heat is absorbed by the PCM. The governing conservation equations are solved using a finite-volume method on orthogonal, rectangular grids. An enthalpy method is used for modeling the melting/re-solidification phenomena. Results from the analysis elucidate the thermal performance of these hybrid heat sinks. The improved performance of the hybrid heat sink compared to a finned heat sink (without a PCM) under identical conditions, is quantified. In order to reduce the computational time and aid in preliminary design, a one-dimensional fin equation is formulated which accounts for the simultaneous convective heat transfer from the finned surface and melting of the PCM at the tip. The influence of the location, amount, and type of PCM, as well as the fin thickness on the thermal performance of the hybrid heat sink is investigated. Simple guidelines are developed for preliminary design of these heat sinks.     

Evaluation of intensity shape and phase change of light pulses withfrequency chirp due to self-phase modulation

A method for evaluating ultrashort light pulses is proposed. The temporal shape and the time-dependent phase change of the pulses is determined using self-consistent iterative calculations based on experimental data of the second-harmonic intensity autocorrelation and the spectra of the pulses. The self-phase modulation originating from the optical Kerr effect (OKE) and/or the saturable effect in the absorber dye solution is taken into account, and two parameters, the amount and the recovery time of the OKE, are introduced into the calculation of the temporal shape and the phase change of the pulses. These two parameters are chosen to give the best agreement of experimental and calculated second-harmonic intensity autocorrelation and spectra. The calculated results determined the lower limits of the recovery time of the OKE     

空间光调制器实现随机相位模板的仿真分析

为了构建基于空间光调制器的实时光学加密系统,采用仿真实验的方式,分析了在双随机相位光学加密系统中使用空间光调制器实现随机相位编码时相位编码参量对加密效果的影响。重点研究了随机相位模板中独立相位调制点的个数及相位调制范围对加密图像质量的影响,并引入相关系数来衡量加密图像和原始图像的差异。结果表明,在设定相关系数阈值为0.1的条件下,独立相位调制点个数达到128×128,相位调制范围达到2π时,加密效果较好。该结果对设计实时光电加密系统有一定指导意义。     

不同孔结构碳电极材料亲电解质性改性及电化学性能研究

碳电极材料良好的亲电解质性能够促进电解质离子在其表面吸附/脱附,从而提高其电化学性能.为了探究亲电解质性对不同孔结构碳电极材料电化学性能的影响,采用悬浮聚合、可逆加成断裂链转移活性聚合和超浓乳液聚合分别制备碳微球、介孔碳和分级多孔碳,并将具有良好亲水性的聚乙二醇(PEG)分子刷接枝在三种碳材料的表面改善它们的亲水系电解...     

Black Titania with Nanoscale Helicity

The fabrication of mesoporous black titanium dioxide (TiO_2?x ) with a chiral nematic organization of core–shell nanorods is reported. Chiral templating of TiO₂ nanoparticles onto gelatin‐functionalized cellulose nanocrystals (CNCs) followed by calcination yields carbonized TiO₂/CNC helical materials that recover white TiO₂ replicas after carbon removal. The hydrothermal surface reduction of the traditional white TiO₂ by ascorbic acid affords freestanding chiral nematic black TiO_2?x. The black TiO_2?x is a visible light active semiconducting mesoporous structure constructed by chiral nematic crystalline–amorphous TiO₂ core–shell nanorods. The chiral black TiO_2?x nanoparticles supported on mesoporous nanocarbon networks are evaluated as lithium‐ion battery anode electrodes. Beyond the current efforts, these black TiO_2?x materials and their composites may be useful in the fields of energy storage and catalysis.     

用三区三元相位滤波器提高近场光存储系统的焦深

为了提高近场固体浸没透镜光存储系统的焦深,设计了三区三元相位滤波器.设计建立在矢量衍射理论基础上,应用MATLAB优化工具箱优化设计出可以获得最大焦深的滤波器结构参数.在设计过程中,我们限定记录光斑的大小与没有滤波器时的光斑大小相等,而光斑的强度减小一半,所设计的滤波器可以使近场固体浸没透镜光存储系统的焦深提高1.6倍...     

Electrooptic materials for digital light beam deflectors

The technology of digital deflectors made significant progress in the past. The success of this development was primarily based on the advances made in the preparation of electrooptic materials. The selection criteria are described here for a material suitable for the particular application under consideration, and a survey is made of the most promising electrooptic materials, both solid state and liquid. The list of solid-state materials comprises representatives of the class of oxygen octahedra ferroelectrics, KDP isomorphs, and AB-type compounds. A section on Kerr liquids begins with considerations for the optimization of the molecular structure and gives experimental results on some newly synthesized materials. Further, the impurity conduction phenomena that are important to the technical performance are described in detail. The final section reviews the present state of digital deflector development.     

细胞培养用品光透射规律的研究

应用紫外分光光度计对细胞培养板盖及培养液的光透射规律进行了初步观察。结果显示，200－280nm波长范围的光很难透过培养板盖（透射率仅2％－10％），对400－800nm波长范围光的透过率达84％左右，含小牛血清和未含小牛血清的PRMI细胞培养液对600－800nm波长范围的光透过较高（透射率分别为78％左右，81％左右），对小于600nm波长的光透过较弱。     

Determination of lines of constant phase in the near-field of ametallic cube and an airplane

A method is presented which enables one to calculate the scattered field very close to the surface of a perfectly conducting body as well as at the surface itself. The method is based on the representation of the scattered field by an integral over the surface current distribution. The integrand is treated by identity transformations that the singular terms can be integrated analytically, while the remaining nonsingular terms are integrated numerically. The surface current distribution is determined by the magnetic field integral equation. The theory is validated by experiments with the scattered field of a metallic cube with an edge length of a wavelength. The current distribution and the normal as well as the tangential electric field at the surface of the cube are measured by small probes, and the results are compared to those of the theory. The theoretical results of the current distributions are presented as gray value graphics-those of the near-field distribution of a cube and an airplane with the help of lines of constant phase     

Background light ray modeling for change detection

This paper is an extension of the work that was originally reported in Shimada et al. (2013). This paper proposes a change detection method based on spatio-temporal light ray consistency. The proposed method introduces light field sensing, which is used to generate an arbitrary in-focus plane. Change detection is performed in a surveillance scene, where the background region can be filtered out by an out-focusing process. This approach resolves a longstanding issue in background modeling-based object detection, which often suffers from false positives in the background regions. To realize this new change detection method, a new feature representation, called the local ray pattern (LRP), is introduced. The LRP evaluates the spatial consistency of the light rays, and this plays an important role in distinguishing whether the light rays come from the in-focus plane or elsewhere. A combination of the LRP and Gaussian mixture model (GMM)-based background modeling realizes change detection in the in-focus plane. Experimental results demonstrate the proposed method’s effectiveness and its applicability to video surveillance.     

相变存储器单元疲劳特性研究

本文主要研究了相变存储器存储单元的疲劳特性。随着操作次数的增多,相变存储器单元在高阻态和低祖态下的阻值逐渐的向着相反的方向变化。同时,本文还讨论了在疲劳操作下,相变单元状态改变所需的操作条件也在逐渐的改变。在最初的一定次数的疲劳操作条件下,单元的阈值电压缓慢的减小,并且在之后的操作中,阈值电压急剧增大。这是由于器件单元的界面效应以及相变区域体积变化工作作用引起的。本文对于之一现象,给出了合理的解释以及数据加以证明。     

Correlation of scanning thermal microscopy and near-field cathodoluminescence analyses on a blue GaN light emitting device

A scanning near-field thermal microscope and a scanning electron microscope/scanning near-field optical microscope hybrid system for near-field cathodoluminescence investigations were used to characterize blue GaN LEDs. Optoelectronic, electronic and thermal device properties are determinable with highest resolution. These results provide an interesting perspective with respect to failure analyses and reliability of the devices.     

Nanoscale light confinement and transport in symmetric hybrid plasmonic waveguides based on silicon nanoslots

正Light confinement at the nanoscale beyond the fundamental diffraction limit is of critical importance to the advancement of next-generation photonic technology,since it offers unprecedented opportunities with dramatically enhanced light-matter interactions.A silicon-nanoslot based symmetric hybrid structure was reported,capable of providing low propagation loss,subwavelength mode size and tight field confinement inside the low-index gap region.The nice optical performance in conjunction with several unique features could enable a number of further applications.In addition to the waveguide proposed here,a number of alternative guiding schemes could also be employed to achieve the goal of propagation loss reduction with subwavelength mode confinement,including structures based on horizontal slot waveguides,and many other configurations capable of forming symmetric or near-symmetric environment along with high-index contrast near the metallic waveguides,such as metal nanostructures covered by low-high-index dielectrics supported by low-index substrates,and coaxial type-structures consisting of metallic nanowires surrounded by dielectrics.     

Accelerating near-field 3D imaging approach for joint high-resolution imaging and phase error correction

The computational complexity and memory requirements of large-scale data seriously affect the application of compressed sensing (CS) in near-field three-dimensional (3-D) imaging system. In addition, as influenced by the measurement environment, the error in echo phase results in imaging defocusing. This paper proposes a CS near-field 3-D imaging approach based on nonuniform fast Fourier transform and phase error correction. It applies the fast Gaussian gridding nonuniform fast Fourier transform technique and Separable Surrogate Functionals with only matrix and vector multiplied to accelerate imaging speed and reduce memory requirements; it adopts the phase error correction technique to realize highly-focused imaging; in addition, a sparse observation approach based on Logistic sequence is proposed in this paper for easy availability of engineering realization for CS imaging. As indicated by numerical analysis and actual measurement in anechoic chamber, the approach proposed in this paper, compared with traditional imaging approaches, has the following advantages: accurate high resolution 3-D image of target can be obtained by applying small amount of observation data (10%); the computational complexity falls from O(LN) to O(3N) and memory occupation quantity drops from O(LN) to O(N); it can effectively perform highly-focused imaging for echo signal with phase error; the measurement matrix designed has better non-coherence and easy availability for engineering realization.