Fabrication of highly transparent self‐cleaning protection films for photovoltaic systems

A moth‐eye anti‐reflective structure was fabricated by hot‐embossing and UV nanoimprint lithography on a solar cell protective film to suppress the reflection of incident light. Moreover, a superhydrophobic surface was developed by reducing the surface energy by forming a hydrophobic self‐assembled monolayer coating on an anti‐reflective structured resin surface. Therefore, the transmittance of incident light was increased by the anti‐reflective structure. As a result, the solar cell efficiency was enhanced and the total accumulated electrical energy generated by a solar cell with a nano‐patterned polymeric film was increased. The efficiency of each solar cell was evaluated by an analysis of its I‐V characteristics using a solar simulator, and the external quantum efficiency according to the wavelength of incident light was analyzed by using an incident photon‐to‐current conversion efficiency system. Finally, the enhancement of the generated power was confirmed by a field test and a power charging experiment. Copyright © 2012 John Wiley & Sons, Ltd.     

利用电阻场板提高SOI-LIGBT的性能

通过在SOI-LIGBT中引入电阻场板和一个p-MOSFET结构,IGBT的性能得以大幅提高.p-MOSFET的栅信号由电阻场板分压得到.在IGBT关断过程中,p-MOSFET将被开启,作为阳极短路结构起作用,从而使漂移区的过剩载流子迅速消失,IGBT快速关断.而且由于电场受到电阻场板的影响,使得过剩载流子能沿着一个更宽的通道流过漂移区,几乎消去了普通SOI-LIGBT由于衬偏造成的关断的第二阶段.这两个因素使得新结构的关断时间大大减少.在IGBT的开启状态,由于p-MOSFET不导通,因此器件的开启特性几乎与普通器件一致.模拟结果表明,新结构至少能增加25%的耐压,减少65%的关断时间.     

基于维纳模型的非线性信道接收端均衡方案

针对功率放大器的非线性问题和多径信道引起的时间色散,提出了一种接收端联合补偿方案。由基于维纳模型的均衡器实现,该均衡器由一个线性滤波器级联一个多项式滤波器组成,所有运算均在接收端完成。仿真结果显示,经过非线性均衡的误码率性能比无非线性均衡时有很大改善,在同一误码率下,信噪比至少降低了3.5 dB。     

短波段频率合成器的设计与调试

设计了基于锁相环的短波段正弦信号合成器,其工作原理为原始的正弦波输出信号由压控振荡器产生,经芯片分频输出一个低频方波信号,参考信号采用Q值较高的晶体产生,然后输出到芯片的分频,在芯片内部输出一个低频方波信号,两路低频方波信号同时由芯片内部的数字鉴相器进行比相,输出一个反映相位误差值的双路差分电压信号到有源环路低通滤波器,经它滤波形成近似直流的信号,控制压控振荡器的变容管反相偏置电压来调整振荡频率。仿真结果达到预期要求。     

Photoresponsive Sponge‐Like Coating for On‐Demand Liquid Release

Many publications report on stimuli responsive coatings, but only a few on the controlled release of species in order to change the coating surface properties. A sponge‐like coating that is able to release and absorb a liquid upon exposure to light has been developed. The morphology of the porous coating is controlled by the smectic liquid crystal properties of the monomer mixture prior to its polymerization, and homeotropic order is found to give the largest contraction. The fast release of the liquid can be induced by a macroscopic contraction of the coating caused by a trans to cis conversion of a copolymerized azobenzene moiety. The liquid secretion can be localized by local light exposure or by creating a surface relief. The uptake of liquid proceeds by stimulating the back reaction of the azo compound by exposure at higher wavelength or by thermal relaxation. The surface forces of the sponge‐like coating in contact with an opposing surface can be controlled by light‐induced capillary bridging revealing that the controlled release of liquid gives access to tunable adhesion.     

An algebra of multiple faults in RAMs

Cell array faults in random-access memories (RAMs) are usually represented by Mealy automata. In such a model, multiple faults should also be representable by automata; in fact, it should be possible to compute the automaton representing a multiple fault from the automata representing the single faults that make up the multiple fault. In this paper we study properties of binary composition operations on automata that are appropriate for the representation of multiple faults in RAMs. First, we derive a set of generic conditions that every composition operation must satisfy. Second, we develop a set of physical conditions that the composition must satisfy in order to apply to stuck-at, transition and coupling faults in RAMs. Third, we represent the transition table rules used by van de Goor and Smit by a composition operation and prove that this operation satisfies both the generic and physical conditions. Fourth, we point out that in some circumstances, it is appropriate to use a different composition operation (defined by us in a previous paper) to permit a different handling of coupling faults in the presence of stuck-at or transition faults. We compare and relate the properties of the two algebras. This work was supported by the Natural Sciences and Engineering Research Council of Canada, Grants OGP0000871 and OGP0000243, and by a grant from the Information Technology Research Centre of Ontario. An extended summary of this paper appears in [1].     

一种适合于衰落信道的BCM码的集分割映射方法

在瑞利衰落信道中,对于一个分组调制(Block Coded Modulation)码的构造通常是通过将具有尽可能大最小乘积距离和汉明距离的成分码与Ungerboeck的集分割映射相结合来实现的,但这种集分割映射方法使得构造的BCM码的路径复杂度大大增加,造成了系统性能的下降。文章给出了一种新的集分割映射方法。仿真结果表明,采用这种方法构造出的BCM码在瑞利衰落信道中的性能较前者有很大的改善。     

Efficient algorithm and systolic architecture for modular division

A new efficient modular division algorithm suitable for systolic implementation and its systolic architecture is proposed in this article. With a new exit condition of while loop and a new updating method of a control variable, the new algorithm reduces the average of iteration numbers by more than 14.3% compared to the algorithm proposed by Chen, Bai and Chen. Based on the new algorithm, we design a fast systolic architecture with an optimised core computing cell. Compared to the architecture proposed by Chen, Bai and Chen, our systolic architecture has reduced the critical path delay by about 18% and the total computational time for one modular division by almost 30%, with the cost of about 1% more cells. Moreover, by the addition of a flag signal and three logic gates, the proposed systolic architecture can also perform Montgomery modular multiplication and a fast unified modular divider/multiplier is realised.     

利用电阻场板提高SOI-LIGBT的性能

通过在SOI-LIGBT中引入电阻场板和一个p-MOSFET结构,IGBT的性能得以大幅提高.p-MOSFET的栅信号由电阻场板分压得到.在IGBT关断过程中,p-MOSFET将被开启,作为阳极短路结构起作用,从而使漂移区的过剩载流子迅速消失,IGBT快速关断.而且由于电场受到电阻场板的影响,使得过剩载流子能沿着一个更宽的通道流过漂移区,几乎消去了普通SOI-LIGBT由于衬偏造成的关断的第二阶段.这两个因素使得新结构的关断时间大大减少.在IGBT的开启状态,由于p-MOSFET不导通,因此器件的开启特性几乎与普通器件一致.模拟结果表明,新结构至少能增加25%的耐压,减少65%的关断时间.     

核壳双层颗粒的外层介质对散射光的影响

简要介绍核壳双层颗粒的散射理论 ,利用数值计算探讨波长不同时核壳双层颗粒与单层颗粒散射光的不同 ,详细分析核壳双层颗粒外层介质的厚度、折射率对整个核壳双层颗粒散射光的影响     

Enhanced backscattering: the universal wave phenomenon

Backscattering enhancement is discussed as a universal wave phenomenon inherent to waves of whatever physical nature: electromagnetic, acoustic, spin, etc. This phenomenon arises due to multichannel wave propagation from a source to a scatterer and back and may be observed in the vicinity of the source because of mutual coherence of waves passing in opposite directions along identical (coherent) channels. Backscattering enhancement may be revealed when the wave field is scattered: by a system of chaotically distributed scatterers or by a system of inhomogeneities; by a body embedded in a turbulent medium; by a single body placed near an interface or within a waveguide (randomness of body position is assumed); by a body of complex form or a system of several scatterers randomly oriented in space; by a rough surface; and by many other physical systems. Possible practical applications of these effects are analyzed     

一种有效的相关噪声背景下宽带相干信号DOA估计算法

利用均匀线阵,本文提出了一种有效的相关噪声下宽带相干信号DOA估计算法.首先,在各个频率点,利用空间差分技术消除色噪声分量,并通过平方操作构造新矩阵;然后,通过聚焦操作得到通用的协方差矩阵;最后,通过使用传播算法估计得到宽带相干信号的DOA.算法能够分辨的相干组中相干信号的个数可以是奇数或是偶数.仿真结果验证了算法的有效性和性能.     

用阱作高阻漂移区的LDMOS导通电阻的解析模型

分析了一个用阱作为耐高压漂移区的LDMOS的导通电阻，提出了带有场极板的高阻漂移区导通电阻的计算公式，改进了双扩散沟道导通电阻的计算公式. 针对一个LDMOS的例子做了计算，并将其与相同参数情况下用MEDICI软件模拟的结果作了对比. 结果表明两者相差仅5%，这说明所得公式可用于该类型LDMOS的分析和设计.     

非熔性激光退火工艺的分子动力学模拟

本文用分子动力学模拟方法研究了266纳米波长的脉冲激光作用下材料的退火过程,提出了一种在非熔性激光退火方式下描述硅和杂质原子行为的微机制。在离子注入之后,硅片表面在高能激光脉冲的作用下,材料的化合键松弛并且部分硅和杂质原子得以摆脱束缚。当后续的激光能量进入固体表面并被价电子吸收时,所产生的原子核反冲,成为原子调整位置和晶格修复的真正的动力学原因。本文用分子动力学方法考察了与能量相关的运动行为。另外,非熔性激光退火对于激光作用能量密度相当敏感,少许过量的激光能量可引起明显的杂质扩散；仿真结果为实际的激光退火实验所支持。     

Curve smoothing for improved feature extraction from digitized pictures

Curves can be expressed by parametrized functions. If a curve is represented by a sampled picture, its parametrized functions appear quantized. The noise induced by quantization can drastically be reduced by an iterative curvilinear filtering of the parametrized functions. At each iteration, this filtering processes the curve coordinates and a better arc length is estimated.     

新型双模介质波导滤波器

为满足5G基站射频前端的要求,提出了一种新型双模介质波导滤波器.在表面镀银的介质填充波导腔里设置两个盲孔和一个耦合槽,可有效控制一对TE201奇偶模.应用上述结构,设计了一个单腔双模滤波器、一个三腔四阶滤波器和一个六腔七阶滤波器.仿真和测试结果表明,在同样阶数下,引入一个双模谐振器能够有效减小滤波器体积:二阶滤波器体积...     

双发射天线对混响室场性能影响的数值分析

提出了双天线激励混响室的方法,研究了双天线激励对混响室场性能的影响。分析了双天线改善混响室场均匀性的原理,对单天线激励下的混响室模型以及处于不同位置的双天线激励下的混响室模型进行了仿真计算,从场均匀性和场强两个方面研究了双天线对混响室场性能的影响,对双天线影响场强的机理进行了分析。研究表明:采用双天线激励改善了混响室工作区域的场均匀性;采用双天线可以降低对功率放大器的要求,降低大型混响室测试成本。最后对双发射天线在大型混响室中的应用进行了探讨和展望。     

有限束宽聚焦贝塞尔－高斯光束轴上的光强分布

运用Ｃｏｌｌｉｎｓ衍射积分推导了贝塞尔－高斯光束经圆光阑限孔透镜后的轴上光强表达式。通过数值计算讨论了轴上光强的分布规律。对贝塞尔光束经回光阑限孔透镜后的轴上光强分布进行了理论和实验研究。     

Ultraprecision grinding of silicon wafers using a newly developed diamond wheel

The damaged layer of 160 nm in thickness is generated on a silicon (Si) wafer, which is the thinnest damaged layer ground by a conventional diamond wheel. This means that the nanoscale damaged layer can not be gained by a traditional diamond wheel. In this study, a novel vitrified diamond wheel is developed. A 96 nm thick damaged layer is obtained by the diamond wheel developed at a feed rate of 15 µm/min, which is the 60% of the limitation induced by a traditional diamond wheel. The damaged layer of 96 nm in thickness consists of an 82 nm amorphous layer at the top, followed by a 14 nm damage crystalline layer underneath. There are no contaminations on the ground Si wafers induced by the novel diamond wheel, beside silicon oxides, which is confirmed by energy dispersive spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction (XRD) and Raman spectra. The diamond wheel has a good vitrified effect, consisting of only diamond and ceria crystalline peaks, which is identified by XRD. Porous microstructure of the diamond wheel is characterized by the field emission scanning electron microscopy.