Meso-nh起电参数化方案研究进展

大量的试验结果表明，霰或冰晶上的转移电荷的极性和量级取决于很多因素。这些影响因素包含碰撞粒子的大小、相对降落末速、云温、液态水含量等，它们都对非感应起电率都有所影响。当在参数化方案中考虑的因素不同时，每次碰撞时所转移电荷的数量和极性均有所差异。     

利用Ka波段云雷达研究青藏高原对流云和降水的垂 直结构及微观物理特征

对第三次青藏高原大气科学试验的Ka波段毫米波云雷达功率谱和雨滴谱仪资料提出了数据处理和质量控制方法,并计算了常用物理量和国内运用很少的物理量(谱偏度、谱峰度、粒子平均下落末速度、大气垂直速度).应用这些物理量对2015年7月16日青藏高原(那曲)一次对流云-降水的垂直结构和微观物理过程进行了研究分析.结果表明:(1)青藏高原地区的降霰对流云在16:00-17:00发展到最强,具有和低海拔地区冰雹云相类似的结构;(2)同一对流云中,地面降霰前后,谱偏度由"正-负-正-负"结构变为负偏度为主,谱峰度由负值转为零值附近,云内粒子更趋于球形;(3)对流云中,强上升气流(≥6 m/s)贯穿-17～-7℃的过冷水层,冰晶与过冷水撞冻和淞附增长形成较大的霰,反之,上升气流较弱(≤4 m/s),淞附增长较弱,霰粒子较小;(4)对流云中,冰晶和霰的融化出现在环境0℃层上方的300 m区域内.     

CCD摄象器件—转移过程

光照射到CCD摄象器件的光敏面上将产生电子——空穴对,其中的少数载流子被时钟脉冲产生的势阱取样,然后聚集起来形成信号电荷包,进而在时钟脉冲驱动下由移位寄存器转移到输出端而取出。本文讨论信号电荷在CCD中的转移过程。在三相CCD中,信号电荷包存储在其中     

CCD电荷转换因子通用测试方法研究

通过分析电荷耦合器件(CCD)图像传感器光电转换、电荷转移、电荷输出的工作原理,提出了一种通用高效的电荷转换因子(CVF)测试方法。该方法采用在CCD感光区域施加直流偏压,水平区施加连续转移的驱动时序的方式,使CCD光敏区以电荷溢出方式往水平区转移电荷,水平区以固定频率不间断转移输出电荷包,从而让CCD输出强度恒定的响应信号;然后通过复位漏电流与输出信号强度的对应关系计算出CCD器件的CVF值。根据该方法的原理设计了一种适应各种CCD器件的通用测试装置,并对多款CCD进行测试验证。结果表明,该方法有效提高了CCD电荷转换因子的测试效率、测试精度和稳定性。     

体陷阱对于体沟电荷耦合器件性能的影响

为了避免表面沟道电荷耦合器件中信号电荷与界面态的互作用造成的转移损失的限制,列入了一种体沟电荷耦合器件(BCCD’s)。它最初的名字叫做埋沟电荷耦合器件。运用一种循环本底电荷可以尽量减少这些限制,实际上通过测试已经获得了非常低的界面态密度(1×10~6cm~2·eV)。界面态也会引起与本底电荷无关的转移噪声。在本文里我们将会看到BCCD’s也会受到类似的影响,只是这些影响一般地讲要小些罢了。这些影响起因于信号电荷与体态的互作用。BCCD也曾被称之为蠕动电荷耦合器件,用它来扩大电极下面的边缘场而获得很高的工作频率。     

静电耗散标签在电子产业中的应用分析

一、静电对电子产业的负面影响 由于物体间的接触分离（摩擦、剥离、撕裂和碰撞等）或电场感应，会产生物体之间或物体内部带电粒子的扩散、转移或迁移，从而形成物体表面电荷堆积，即呈现带电现象。这种现象可能导致物体表面电荷对空气中带异性电荷的微粒子尘埃的吸引，造成电子敏感元器件绝缘性能的降低、结构腐蚀或破坏。[第一段]     

电子倍增CCD中电荷载流子倍增寄存器的分布式等效电路模型

为了研究电子倍增电荷耦合器件(EMCCD)中电荷载流子倍增寄存器(CCM)内部电荷的倍增及转移特性,提出了一种适用于CCM的电荷传输机制仿真的分布式等效电路模型.利用泊松方程求解了均匀掺杂条件下CCM单元的电势分布,通过基尔霍夫电压定律(KVL)得到了该单元的最大电势表达式,从而得到了其分布式等效电路.同时,结合该单元...     

质子辐射导致CCD热像素产生的机制研究

空间高能质子作用于电荷耦合器件(CCD)产生的热像素是空间成像系统性能退化的主要原因之一。为深入认识质子辐射导致CCD产生热像素的规律和机制,对行间转移CCD进行了不同能量(3,10,23 MeV)的质子辐射试验,研究了辐射导致CCD暗信号的退化和热像素产生的规律。试验结果表明,在较低辐射注量1E9 p/cm²下,CCD的暗信号退化很小,但热像素急剧增加。质子辐射能量越大,产生的热像素数量越多。结合粒子输运计算与理论分析表明,热像素产生原因是质子与半导体材料中的原子非弹性碰撞而形成的团簇缺陷。     

红外电荷耦合器件

电荷耦合的概念简单而又极其实用,是以电荷包在金属-氧化物-半导体(MOS)结构中的转移为基础的。将简单的电荷耦合器件(CCD)与各种模拟形式结合起来,可以发展成多样化的器件,在红外探测和成象方面,采用电荷耦合器件及其有关的器件,最初引入大面积的探测器阵列是显著改进灵敏度和分辨率的关键。此外,通过这种改进,可以降低电、热损耗,减小体积和重量等。本文评述红外敏感的电荷耦合器件(即IRCCD)的物理特性及工作原理。IRCCD可分为单片器件和混合器件两大类。单片器件的红外敏感衬底可以是窄带半导体,也可以是有适宜杂质电离能级的非本征半导体;混合器件则由选取的各种红外探测器耦合硅标准CCD而     

Ethernet网络接口卡评比总结

BYTE杂志对100种适用于ISA总线系统的16位和8位Ethernet网络接口卡(NIC)进行了详细测试和比较,最近公布了评比结果.总的来说,NIC比一年前推出的体积更小,价格更便宜,使用更方便.此外,在整个市场上,NIC的性能也趋于稳固:例如,所测试的速度最慢的16位NIC(Intellicom公司的Ether Plus—16C)只比速度最快的NIC(3Com公司的EtherLink Ⅲ)慢10%.之所以选择Ethernet NIC,是因为Ethernet是最流行的网络.之所以选择ISA,是因为它是最重要的PC总线结构.今天的大多数计算机仍采用16位总线,其上还可能配有一两个8位插槽.为了适应较老式计算机的需要,许多16位NIC卡也可使用于8位插槽.所以,16位和8位NIC被列为评比对象.     

Quantum Theory of Contact Electrification for Fluids and Solids

A unified quantum‐mechanical model of contact electrification that provides a microscopic basis for the Volta–Helmholtz–Montgomery hypothesis is presented. The model can represent metals, semiconductors, or insulators, in either fluid or solid phase, and with an effective electron transfer parameter as the driving mechanism. Known experimental results such as the charging of similar materials, the charging of similar materials with different contact orientation, the surface charge mosaic, and the higher efficiency of charge transfer for a liquid–solid contact, compared to a solid–solid one, are reproduced. A quantum‐mechanical charge oscillation in the femtosecond to picosecond regime is predicted to take place. Coulomb interaction is found to have an impact on not just the charge transferred but also the period of charge oscillation.     

Unraveling Temperature‐Dependent Contact Electrification between Sliding‐Mode Triboelectric Pairs

The underlying mechanism on contact electrification (CE) has remained a topic of debate over centuries, and it is argued to be due to electron transfer, ion transfer, and/or even material species transfer. Recently, a previous study shows that CE is dominated by electrons, at least for solid–solid cases. Herein, by using a model detailing the charge transfer between triboelectric surfaces and thermionic emission of electrons via employing a sliding mode Ti–SiO₂ triboelectric nanogenerator (TENG), surface charge decay behavior is scrutinized in lateral‐sliding mode during operation at high temperature. The temperature dependence of TENG electric output contributes to characteristic metal–dielectric and dielectric–dielectric CEs, thereby providing further evidence that electrons are the dominating transferred charges in CE. The total surface charge output of the TENG is rationalized as a direct consequence of the coupling of the rate of electron thermionic emission, the charge transfer rate of CE, and the changing rate of the contacted area between the two materials. When the contacting area is larger than the displaced area, the CE between the two materials is the major contributor to measured surface charge. Conversely, the thermionic emission of the exposed surfaces dictates when the contacting area is smaller.     

Effects of Metal Work Function and Contact Potential Difference on Electron Thermionic Emission in Contact Electrification

Triboelectric nanogenerator (TENG) is a direct measure of the surface charge density, thus providing a novel and powerful tool to study the essential mechanism of contact electrification (CE). A variety of TENGs including a Pt‐Al₂O₃ TENG, Au‐Al₂O₃ TENG, Ti‐Al₂O₃ TENG, Al‐Al₂O₃ TENG, and SiO₂‐Al₂O₃ TENG are prepared in this study. After introducing initial charges on the Al₂O₃ surface of the TENGs, the long‐term evolution of surface charge quantity is investigated at different temperatures. The results show that charge variation of all the TENGs is analogous to exponential decay and is in accord with the thermionic emission model, verifying the electron transfer dominated mechanism of CE. Additionally, it is explored for the first time that the potential barrier of materials can be regulated by changing the contacting metals or dielectrics. Regulation of the barrier at high temperatures fully excludes the influence of ions from moisture and functional groups, which further indicates the dominant role played by electron transfer in CE. Surface state models for explaining barrier regulation during CE for both metal–dielectric and dielectric–dielectric pairs are proposed. This study provides a new perspective of the exploration of CE, and a novel method for further increasing or rapidly eliminating electrification of charged materials.     

Arctic Sea Ice Type and Concentration Mapping Using Passive and Active Microwave Sensors

The mapping of ice type concentrations in the Arctic is important for commercial operations and for climate-related research. Algorithms based on moderate-resolution passive microwave sensors for mapping first-year ice and multiyear ice concentrations suffer from a number of known problems. In this paper, it has been shown that QuikSCAT scatterometer data can add complimentary information to that available from passive microwave, which can assist in separating different ice classes. Specifically, we identify a class of ice that exhibits a passive microwave signature which is characteristic of first-year ice, but has a scatterometer signature which is typical of multiyear ice. We track the evolution and distribution of this new ice class throughout the Arctic during the winter season of 2003-2004 and compare the results against the U.S. National Ice Center (NIC) ice charts. It has been found that the new ice class is predominantly multiyear ice and is especially prevalent in the Fram Strait and the high Arctic regions north of the islands Franz Josef Land and Severnaya Zemlya. A simple algorithm has been proposed that enables a passive microwave-based partial ice concentration algorithm (for example, the NT algorithm based on Special Sensor Microwave/Imager data) to be adapted using QuikSCAT scatterometer data, so that the new ice class is corrected from the first-year ice class to the multiyear ice category. The algorithm performance is measured against the NIC ice charts. We provide a discussion regarding the possible physical causes of the effects that have been observed and described     

Creating Ultrahigh and Long-Persistent Triboelectric Charge Density on Weak Polar Polymer via Quenching Polarization

To achieve high charge density for the triboelectric polymer is a crucial task for fabricating triboelectric nanogenerators (TENGs). This work has developed a quenching polarization (QP) method to create ultrahigh and long-persistent triboelectric charge on the triboelectric polymer with weak dipole polarity. The Ethylene chlorotrifluoroethylene copolymer (ECTFE) film can reach a charge density of 391 µC m⁻² in the vertical contact mode by using this QP treatment, which is 200% higher than the result achieved by the most widely used method of corona polarization. The mechanism of the improvement through QP on the triboelectric properties is studied on the basis of the polarization induced grain refinement and interfacial trapping. The QP-treated ECTFE can maintain ultra-high charge density for both solid-solid and solid-liquid TENG. More interestingly, the charge induced by QP treatment is so persistent that it produces a recoverable discharging phenomenon for solid-liquid TENG, which has never been observed before. This QP method provides a different approach for fabricating high-performance triboelectric materials, while the QP-induced changes in crystallization and tribo-charge density can help to complete the physical understanding of the electrification mechanism of triboelectric polymer.     

Liquid–Solid Triboelectric Probes for Real-Time Monitoring of Sucrose Fluid Status

Triboelectric probes have rapidly developed as an efficient tool for understanding contact electrification at liquid–solid interfaces. However, the liquid–solid electrification process is susceptible to interference from chemical components in mixed solutions, severely limiting the potential applications of triboelectric probes in various liquid environments. This study for the first time reports a triboelectric probe capable of sucrose solution concentration sensing, finding that the dissolution of sucrose destroys the hydrogen bond network between water molecules and forms sucrose–water hydrogen bonds, which alters the fluid mechanics characteristics of the solution and enhances its conductivity, thereby reducing the droplet size and causing an ion charge shielding effect that significantly affects the electron transfer in liquid–solid contact electrification. Owing to the feedback of the triboelectric probe on the sucrose concentration gradient-type sensing electrical signals, efficient sensing of sucrose solution was achieved (sensitivity of −0.0038%⁻¹, response time of 90 ms). The triboelectric probe is also used as a wireless smart terminal to enable real-time detection of sucrose solution. This work contributes to the understanding of the structure–function relationship between micro hydrogen bonding and macro performance, and provides a promising solution for building sustainable intelligent sensors.     

Fast subspace tracking and neural network learning by a novelinformation criterion

We introduce a novel information criterion (NIC) for searching for the optimum weights of a two-layer linear neural network (NN). The NIC exhibits a single global maximum attained if and only if the weights span the (desired) principal subspace of a covariance matrix. The other stationary points of the NIC are (unstable) saddle points. We develop an adaptive algorithm based on the NIC for estimating and tracking the principal subspace of a vector sequence. The NIC algorithm provides a fast on-line learning of the optimum weights for the two-layer linear NN. We establish the connections between the NIC algorithm and the conventional mean-square-error (MSE) based algorithms such as Oja's algorithm (Oja 1989), LMSER, PAST, APEX, and GHA. The NIC algorithm has several key advantages such as faster convergence, which is illustrated through analysis and simulation     

高比例清洁能源接入与终端电气化率提升对城市电网规划影响分析

针对清洁能源高比例接入和终端电气化率不断提升导致的城市电网规划边界模糊,以及源网荷储各元素之间耦合关系增强等带来的不确定问题,通过分析清洁能源高比例接入和终端电气化率提升对城市电网规划的影响,探讨了城市电网发展遇到的瓶颈,提出了新型城市电网规划方案相关建议,为新形态城市电网规划提供参考意见。     

A Bayesian classification model for sea ice roughness fromscatterometer data

For sea ice in the Baltic Sea, surface scattering can be regarded as the dominant scattering mechanism at C-band. In this paper, a new statistical method is introduced for making statistical inferences about the underlying ice surface roughness on the basis of one-dimensional (1D) scatterometer data y. The central parameter in the hierarchical model applied in the context is a mixture parameter p, which indicates the degree of surface roughness in ice surface. Several questions related to the occurrence of different ice classes on a transect can be solved with the aid of the posterior distribution [p|y]. An empirical approximation for the posterior distribution is computed by using Markov Chain Monte Carlo methodology. The efficiency of the suggested approach is investigated by analyzing a C-band HH-polarization helicopter-borne HUTSCAT scatterometer data. The results provided by the statistical model show good agreement with a video-based ice type classification