表面改性多孔二氧化硅减反膜的稳定性研究

以正硅酸乙酯为原料,采用溶胶-凝胶法制备SiO_2溶胶,通过提拉法涂制多孔SiO_2减反膜,并在多孔SiO_2减反膜上涂制一层甲基三乙氧基硅烷(MTES)预聚体。通过疏水的MTES预聚体涂制在多孔SiO_2减反膜上,对多孔SiO_2减反膜的表面进行改性,以提高膜层的环境稳定性。经过表面改性的复合膜层的透过率峰值可达99.67%,折射率为1.231,水接触角达123.6°,在相对湿度为95%的环境中放置475 d后膜层的峰值透过率为99.09%,稳定性提高明显。膜层表面平整,激光损伤阈值约为24.5 J/cm~2。     

含氟有机硅改性多孔二氧化硅减反膜

二氧化硅减反膜的结构疏松,且胶粒表面存在大量羟基,膜层极易吸附环境中的水分和有机蒸气,透射比稳定性较低.为了改善原有减反膜的环境稳定性,以3,3,3-三氟丙基三甲氧基硅烷和3,3,3-三氟丙基甲基二乙氧基硅烷为掺杂剂,正硅酸乙酯为前躯体,采用溶胶-凝胶法制备了两个系列的SiO2减反膜.结果表明,含氟硅氧烷改性的系列膜层的疏水性能均得到显著增强.CF3-CH2-CH2-Si或CF3-CH2-CH2-Si-CH3质量分数在0.40%～1.5%的范围内时,二氧化硅膜层的减反效果较好.掺入含氟硅氧烷在一定质量分数时,膜层的抗激光损伤性能受到的影响不大.10-3Pa高真空环境的实验表明,膜层的稳定性有较大提高,含氟硅氧烷改性延长了减反膜的使用寿命.     

双波段宽带减反膜的研究

根据电视/红外双色制导的要求,研制了锗酸盐基底上的双波段宽带减反膜。其膜系设计采用二氧化钛和二氧化硅分别作为高、低折射率膜料的13层膜堆,镀制的膜层满足环境稳定性标准。在0.56~0.75μm波长范围内,双面镀膜后的平均透过率大于98%,单面平均剩余反射率不超过0.5%;在3.6~4.8μm波长范围内,双面镀膜后的平均透过率至少可达到85%,单面平均剩余反射率不超过1.5%。     

溶胶-凝胶法制备疏水性自组装SiO2薄膜

 以正硅酸乙酯（TEOS）和六甲基二硅氮烷（HMDS）为前驱体,研究了引入聚乙烯吡咯烷酮（PVP）对膜层的影响,在碱催化条件下制备了改性的二氧化硅溶胶,并采用提拉涂膜的方法在石英基底上涂膜。对不同组分的薄膜,先经热处理或紫外辐照处理,然后用十八烷基三氯硅烷（OTS）/甲苯溶液对膜层表面进行化学修饰,制备出疏水性能良好的纳米二氧化硅自组装薄膜,分析了不同后处理方法对膜层透过率、接触角、膜层表面微观形貌和激光损伤阈值影响。实验结果表明：溶胶中加入PVP提高了膜层的平整度,经OTS改性后膜层疏水性和激光损伤阈值均得到提高。     

低温制备防潮耐真空污染二氧化硅减反膜

采用溶胶-凝胶法,以正硅酸乙酯为前驱体,氨水为催化剂,通过六甲基二硅氮烷(HMDS)对溶胶改性,使用提拉法镀膜,并经过低温热处理制备了具有良好防潮抗真空性能的SiO_2减反膜.对薄膜的防潮性能、水接触角、真空抗污染能力、结构等进行了测试表征.结果表明:掺HMDS的溶胶制备的二氧化硅膜层峰值透过率为99.7%;水接触角可达154°;在相对湿度大于90%的环境中保存7天和在二甲基硅油作为污染源的真空环境中放置30天,透过率仅分别下降0.05%和0.35%,防潮耐真空稳定性较未改性薄膜都得到极大提高.     

等离子体结合六甲基二硅胺烷处理提升增透膜抗真空污染性能研究

本文采用溶胶-凝胶法制备了SiO₂增透膜,然后对其进行等离子体结合六甲基二硅胺烷（HMDS）表面改性处理。研究了后处理改性对增透膜表面形貌、微观结构、光学性能及激光损伤性能的影响规律,获得了抗真空有机污染的二氧化硅增透膜。结果表明,增透膜在采用等离子体结合HMDS表面改性处理后,膜层收缩、粗糙度下降、极性羟基等有机基团含量减少;两步后处理改善了增透膜膜层结构和光学性能,显著提高了膜层疏水能力和真空条件下的抗污染性能,并且对溶胶-凝胶二氧化硅增透膜的高损伤阈值属性不产生影响。     

晶硅异质结太阳电池表面三层减反膜的设计与分析

晶硅异质结太阳电池表面的减反层是ITO薄膜,其低的紫外透过率、高的近红外光学损耗限制了电池效率的提升。为此,本文设计了三层减反膜来减小ITO薄膜的光学损耗。利用光学薄膜膜系设计软件TFCalc、光线追迹程序(OPAL 2)和太阳电池模拟软件PC1D对三层减反膜的光学性能和相应电池的电学性能进行了模拟和分析,并对折射率色散效应、晶硅表面形貌以及各膜层的厚度容差进行了讨论。结果表明:考虑折射率色散效应的三层减反膜比ITO薄膜的寄生吸收更小,减反射带宽更大;绒面硅表面减反膜比平面硅表面减反膜的加权平均光学损耗降低了2.43个百分点,相应电池的短路电流密度和转换效率分别提高了0.82 mA/cm²和0.34个百分点;减反膜中低折射率的SiO_x膜层具有更大的厚度容差范围。     

离子束辅助淀积低温微光学元件红外宽带增透膜

简要叙述了锗基片微光学元件红外宽带减反膜的设计与制作。着重介绍了离子束辅助淀积制备该膜系的过程，给出了用该方法制作８～１２μｍ波段的减反膜的测试曲线，它具有峰值透过率高，在设计波长范围内的平均透过率大于９７％以上，膜层附着好，可以切割和擦洗，可以在室温和１００Ｋ低温下反复循环使用。     

PECVD技术制备多波段渐变减反膜

介绍了利用傅里叶变化法设计多波段渐变减反膜的原理和方法,研究了采用该方法设计多波段减反膜时Q函数的优选流程,给出了最优Q函数。设计优化得到了在350~5000nm波段范围平均透过率大于90%的多层渐变减反膜系结构,并采用等离子体增强化学气相沉积(PECVD)技术完成了样片的制备。实验结果表明,镀制的样片在350~5000nm波段范围的平均透过率为90.55%,满足光谱特性的要求。     

溶胶凝胶ZrO2/SiO2宽带减反膜的制备与性能

采用溶胶凝胶法制备得到以正丙醇锆和正硅酸乙酯为前驱体的ZrO₂和SiO₂溶胶,通过TFCalc光学薄膜软件模拟了ZrO₂/SiO₂三层“宽M型”基频二倍频减反膜,并使用提拉法制备得到了该均匀膜层。三层减反膜在527 nm和1053 nm处的透过率约为99.5%,且透过率大于99%的波长范围均超过150 nm。经热处理后的膜层表面均方根粗糙度为1.34 nm,表面平整性良好;并运用1-on-1激光损伤阈值测试方法测得该减反膜的零几率激光损伤阈值达到36.8 J·cm^-2(1064 nm,10.7 ns)。     

微柱高效液相色谱与火焰光度检测器池用的初步研究

本文研究了常规高效液相色谱（ＨＰＬＣ）及微柱高效液相色谱（Ｍｉｃｒｏ－Ｃｏｌｕｍｎ ＨＰＬＣ）与气相色谱火焰光度检测器（ＦＰＤ）的联用技术及其应用。丁基锡等化合物经ＨＰＬＣ分离后,流出液通过ＦＰＤ进行特效检测。接口采用将毛细管直接引入燃烧头的方式。文中对各有关参数进行了选择、优化和讨论,对ＦＰＤ作为ＨＰＬＣ的在线检测器的呆能性作了初步探讨。     

奇异值分解滤波器在超声造影成像的应用及性能分析*

信噪比和造影-组织残留比是衡量造影性能的主要指标,现有提升方法多从频域入手,存在两个缺陷:噪声、组织残留与造影剂信号存在频带重叠时(如二次谐波),频域滤波性能受限;虽然非线性基波、次谐波等方法可解决频带重叠问题,但面对前端电路非对称性及信号饱和导致的组织残留,仍难在频域进行滤除。奇异值分解滤波器是一种非频域方法,可将接收信号分解成若干空时域子空间,通过对子空间进行保留及重组,可提取微泡且滤除噪声与组织残留。该文研究了该类滤波器在造影成像的应用,并采用性能分析实验论证了其可行性与优越性。     

Multi-objective control optimization for semi-active vehicle suspensions

In this paper we demonstrate a method for determining the optimality of control algorithms based on multiple performance objectives. While the approach is applicable to a broad range of dynamic systems, this paper focuses on the control of semi-active vehicle suspensions. The two performance objectives considered are ride quality, as measured by absorbed power, and thermal performance, as measured by power dissipated in the suspension damper. A multi-objective genetic algorithm (MOGA) is used to establish the limits of controller performance. To facilitate convergence, the MOGA is initialized with popular algorithms such as skyhook control, feedback linearization, and sliding mode control. The MOGA creates a Pareto frontier of solutions, providing a benchmark for assessing the performance of other controllers in terms of both objectives. Furthermore, the MOGA provides insight into the remaining achievable gains in performance.     

Analytical performance study of solar blind non-line-of-sight ultraviolet short-range communication links

Motivated by recent advances in solid-state incoherent ultraviolet sources and solar blind detectors, we study communication link performance over a range of less than 1 km with a bit error rate (BER) below 10(-3) in solar blind non-line-of-sight situation. The widely adopted yet complex single scattering channel model is significantly simplified by means of a closed-form expression for tractable analysis. Path loss is given as a function of transceiver geometry as well as atmospheric scattering and attenuation and is compared with experimental data for model validation. The BER performance of a shot-noise-limited receiver under this channel model is demonstrated.     

Optimized performance map of an EAM for pulse generation and demultiplexing via FROG characterization

We demonstrate the complete characterization of a sinusoidally driven electro-absorption modulator (EAM) over a range of RF drive voltages and reverse bias conditions. An accurate performance map for the EAM, to be employed as a pulse generator and demultiplexer in an optical time division multiplexed (OTDM) system, can be realized by employing the Frequency Resolved Optical Gating technique. The generated pulses were characterized for chirp, extinction ratio (ER) and pulse width (<4 ps). The optimization of the EAM’s drive conditions is important to ensure that the generated pulses have the required spectral and temporal characteristics to be used in high-speed systems. The ER and pulse width also influence the demultiplexing performance of an EAM in an OTDM system. This is confirmed by utilizing the EAM as a demultiplexer in an 80 Gb/s OTDM system and measuring the BER as a function of the received optical power for various values of the ER and pulse width. It is of paramount importance to accurately characterize the performance of each individual EAM as the modulators characteristics are device dependant, thus optimum performance can be achieved with slight variations to the device’s drive conditions. By employing FROG, an optimum performance map of each specific device can be deduced. Simulations carried out verified the experimental results achieved.     

Combined Signal Processing Based Techniques and Feed Forward Neural Networks for Pathological Voice Detection and Classification

This paper presents the pathological voice detection and classification techniques using signal processing based methodologies and Feed Forward Neural Networks (FFNN). The important pathological voices such as Autism Spectrum Disorder (ASD) and Down Syndrome (DS) are considered for analysis. These pathological voices are known to manifest in different ways in the speech of children and adults. Therefore, it is possible to discriminate ASD and DS children from normal ones using the acoustic features extracted from the speech of these subjects. The important attributes hidden in the pathological voices are extracted by applying different signal processing techniques. In this work, three group of feature vectors such as perturbation measures, noise parameters and spectral-cepstral modeling are derived from the signals. The detection and classification is done by means of Feed Forward Neural Network (FFNN) classifier trained with Scaled Conjugate Gradient (SCG) algorithm. The performance of the network is evaluated by finding various performance metrics and the the experimental results clearly demonstrate that the proposed method gives better performance compared with other methods discussed in the literature.     

PVA栅绝缘层浓度对P3HT有机场效应晶体管性能的影响

采用溶液制备法制备了用PVA作为绝缘层、P3HT作为有源层的有机场效应晶体管,,研究了不同浓度PVA栅绝缘层对器件性能的影响。实验结果显示,以质量分数为8%的PVA溶液制备的栅绝缘层具有最好的性能,器件的场效应迁移率为0.31 cm²·V^-1·s^-1,阈值电压为-6 V。进一步分析了PVA栅绝缘层浓度对器件性能提高的原因,结果表明,对于制备溶液化的有机场效应晶体管,选取合适的PVA栅绝缘层浓度非常重要。     

Multi-Scale Gaussian Processes： a Novel Model for Chaotic Time Series Prediction

Based on the classical Gaussian process （GP） model, we propose a multi-scale Gaussian process （MGP） model to predict the existence of chaotic time series. The MGP employs a covariance function that is constructed by a scaling function with its different dilations and translations, ensuring that the optimal hyperparameter is easy to determine. Moreover, the scaling function with its different dilations and translations can form a set of complete bases, resulting in the fact that the MGP can acquire better prediction performance than the GP. The experiments can lead to the following conclusions： （i） The MGP gives a relatively better prediction performance in comparison with the classical GP model. （ii） The prediction performance of the MGP is competitive with support vector machine （SVM）. They give better performance as compared to the radial basis function networks.     

采用复合吸附剂多功效热管型吸附制冷机

设计制造了一台采用复合吸附剂(氯化钙和活性炭)-氨工作对的双床多功效热管型吸附制冷机,并进行了大量实验,获得了新型热管型吸附制冷系统的制冷特性。本系统分别采用丙酮或水为热管工作液,以加热器加热来模拟渔船余热加热。实验得出渔船制冰工况和船舶空调工况下的单位质量吸附剂的制冷功率SCP和制冷系统COP。结果显示水热管工质更适合于船舶余热应用。     

High-performance inverters based on ambipolar organic-inorganic heterojunction thin-film transistors

This work reports on the integration of organic and inorganic semiconductors as heterojunction active layers for highperformance ambipolar transistors and complementary metal-oxide-semiconductor(CMOS)-like inverters. Pentacene is employed as a p-type organic semiconductor for its stable electrical performance, while the solution-processed scandium(Sc) substituted indium oxide(Sc In O) is employed as an n-type inorganic semiconductor. It is observed that by regulating the doping concentration of Sc, the electrical performance of the n-type semiconductor could be well controlled to obtain a balance with the electrical performance of the p-type semiconductor, which is vital for achieving high-performance inverters. When the doping concentration of Sc is 10 at.%, the CMOS-like logic inverters exhibit a voltage gain larger than 80 and a wide noise margin(53% of the theoretical value). The inverters also respond well to the input signal with frequency up to 500 Hz.