关于非对称含错学习问题的困难性研究

由于基于最坏情况困难假设等优点,基于格的密码被认为是最具前景的抗量子密码研究方向。作为格密码的常用的两个主要困难问题之一,含错学习(LWE)问题被广泛用于密码算法的设计。为了提高格密码算法的性能,Zhang等人(2019)提出了非对称含错学习问题,该文将从理论上详细研究非对称含错学习问题和标准含错学习问题关系,并证明在特定错误分布下非对称含错学习问题和含错学习问题是多项式时间等价的,从而为基于非对称含错学习问题设计安全的格密码算法奠定了理论基础。     

Approximations of One-Dimensional Digital Signals Under the$l^infty$Norm

Approximation of digital signals by means of continuous-time functions is often required in many tasks of digital to analog conversion, signal processing, and coding. In many cases the approximation is performed based on an$l^2$optimality criterion; in this paper we study approximations of one-dimensional signals under the$l^infty$norm. We first introduce approximations in linear spaces, for which linear programming methods are known. For the particular case of linear approximations (i.e., first-order polynomials), we propose a geometric solution that is shown to be computationally more efficient than the linear programming approach. Then, we study the problem of piecewise approximations, i.e., dividing the domain into intervals and approximating the signal in linear spaces within every segment independently, so as to reach an optimal noncontinuous approximation. Given an error bound$delta$, we establish a strategy to determine the minimum number$k$of segments for which the approximation is guaranteed to produce an error within$delta$. We then show how to find the optimal partition that gives the piecewise$l^infty$optimal solution with$k$segments. The computational complexity of the algorithms is studied, showing that in many practical situations, the number of operations is$O(n)$, with$n$being the number of samples.     

Inverse Source Problem in the Spheroidal Geometry: Vector Formulation

A formulation based on Lagrangian optimization and spheroidal vector wave functions is presented for the vector electromagnetic inverse source problem of deducing a time-harmonic current distribution that is confined within a spheroidal volume, that generates a prescribed radiation field, and that is subject to given constraints on the source functional energy, which characterizes antenna current level, and the source's reactive power, which models antenna resonance matching. The paper includes computer simulation results illustrating the derived inverse theory.     

Extended Through-Short-Delay Technique for the Calibration of Vector Network Analyzers With Nonmating Waveguide Ports

The extension of the through-short-delay (TSD) technique to the calibration of two-port vector network analyzers (VNAs) with nonmating waveguide ports is reported. The method retains the well-known high accuracy of the basic TSD technique while it enables to calibrate VNAs using two waveguide ports with different cross sections. Comparisons with the reciprocal-short–open–load technique commonly adopted to calibrate VNAs with nonconnectable ports and with theoretical data are reported. The present method can be adopted as either a one- or a two-tier calibration technique.      

车牌字符的预处理研究

由于在汽车牌照自动识别系统中，因天气或拍摄角度等原因造成车牌图像模糊、倾斜和光照不均等现象，给车牌的处理带来了很大困难。本文针对这些问题，提出了相应的处理方法，高效地完成了车牌字符的预处理。     

空域红外图像的背景噪声分析及预处理

文中就如何提高空域背景下弱小目标的信噪比问题展开讨论，基于对背景噪声的统计分析提出了自适应滤波和小波分析两种图像预处理算法，达到抑制背景噪声，增强小目标的目的，并将二者进行了性能分析。     

参数据挖掘中的预处理算法研究

针对飞参数据的特点．从野值剔除和属性选择两个方面对飞参数据预处理进行了研究，提出了基于残差检验的野值别除方法和基于神经网络的两阶段属性选择方法。在野值剔除方法中，首先计算原始序列和拟合序列的残差．再用门限值对残差进行检验；在属性选择方法中，先用神经网络对属性的相对重要度进行排序，再用神经网络进行属性选择。最后用实验验证了两方法的有效性。     

飞参数据挖掘中的预处理算法研究

针对飞参数据的特点,从野值剔除和属性选择两个方面对飞参数据预处理进行了研究,提出了基于残差检验的野值剔除方法和基于神经网络的两阶段属性选择方法。在野值剔除方法中,首先计算原始序列和拟合序列的残差,再用门限值对残差进行检验;在属性选择方法中,先用神经网络对属性的相对重要度进行排序,再用神经网络进行属性选择。最后用实验验证了两方法的有效性。     

智能车载预警系统中的夜间图像预处理技术研究

文章对用智能车载预警系统获取的夜间图像进行了预处理,包括平滑滤波、锐化、阈值分割、数学形态学和求连通域。通过算法的对比试验,选择出了适合所获取的图像的一套方法。     

WCDMA网络越区覆盖问题分析与解决

文章针对WCDMA网络中存在的越区覆盖问题进行讨论,对越区覆盖的原因、危害、检测分析方法进行了概述,提出了相应解决措施,并给出了中国联通泰安分公司3G网络中的实际案例。     

ASIC电路中时钟驱动的抗单粒子加固

CMOS工艺制成的ASIC电路在太空中应用时,在辐射效应的影响下可能导致数据出错,影响整个系统的可靠性.在ASIC电路的抗辐射设计时,最关注的是时钟(CLK)驱动电路受辐射效应的影响.为此,文章分析了深亚微米工艺条件下CLK电路受到单粒子瞬态扰动效应(SET)的影响,为消除SET效应对CLK电路的扰动提出了四种加固方案...     

Solving the Redundancy Allocation Problem With a Mix of Components Using the Improved Surrogate Constraint Method

When designing a system, there are two methods that can be used to improve the system's reliability without changing the nature of the system: 1) using more reliable components, and/or 2) providing redundant components within the system. The redundancy allocation problem attempts to find the appropriate mix of components & redundancies within a system in order to either minimize cost subject to a minimum level of reliability, or maximize reliability subject to a maximum cost and weight. Redundancy allocation problems can be classified into two groups; one allows the system to have a mix of components with different characteristics incorporated in the system, while the other only allows one type of each component. The former group has a much larger solution space compared to the latter, and therefore obtaining an exact optimal or even a high quality solution for this problem may be more difficult. Optimization techniques, based on meta-heuristic approaches, have recently been proposed to solve the redundancy allocation problem with a mix of components. However, an exact solution method has not been developed. In this paper, we develop an exact solution method, based on the improved surrogate constraint (ISC) method, and use this method to find optimal solutions to problems previously presented in the literature     

CMOS/SOI 4Kb SRAM总剂量辐照实验

研究了CMOS/SOI 4Kb静态随机存储器的抗总剂量辐照性能.CMOS/SOI 4Kb静态随机存储器采用1K×4的并行结构体系,其地址取数时间为30ns,芯片尺寸为3.6mm×3.84mm;在工作电压为3V时,CMOS/SOI 4Kb静态随机存储器抗总剂量高达5×105Rad(Si),能较好地满足军用和航天领域的要求.     

Fast Control of Filter for Sensorless Vector Control SQIM Drive With Sinusoidal Motor Voltage

A pulsewidth-modulated (PWM) voltage applied to a squirrel-cage induction motor (SQIM) can cause high bearing currents, heating of rotor shaft, voltage spike across the motor terminals, etc. Filtering of this PWM voltage to obtain a sinusoidal output voltage can be a solution to this problem. However, a passive L-C filter makes the dynamic performance of the drive poor for high-performance control application. In this paper, a feed-forward control strategy for the L-C filter is proposed to have a good bandwidth for the filter output voltage. This filter control strategy is introduced along with a sensorless vector control strategy for the SQIM drive. This complete strategy retains the high dynamic performance of the drive even with the L-C filter. In this paper, a three-level converter is used as a voltage source inverter for the drive to have a less filter-size requirement. The control strategy is verified on a 7.5-hp SQIM drive with a three-level insulated-gate bipolar-transistor inverter and L-C filter. Experimental results validate the high dynamic performance of the drive with filter.     

CMOS/SOI 4Kb SRAM总剂量辐照实验

研究了CMOS/SOI 4Kb静态随机存储器的抗总剂量辐照性能.CMOS/SOI 4Kb静态随机存储器采用1K×4的并行结构体系,其地址取数时间为30ns,芯片尺寸为3.6mm×3.84mm;在工作电压为3V时,CMOS/SOI 4Kb静态随机存储器抗总剂量高达5×105Rad(Si),能较好地满足军用和航天领域的要求.     

交流电动机矢量控制变压变频调速系统（一） 第一讲 矢量控制的基本概念

本文首先对直流电动机电磁转矩和异步电动机电磁转矩之间的内在联系进行了介绍，在此基础上，给出矢量控制的基本概念，最后，讨论了异步电动机矢量控制方法的基本思想，给出了矢量控制系统的总体（思路）框图。     

The Regulator Problem for Linear Systems With Saturations on the Control and its Increments or Rate: An LMI Approach

This paper solves the problem of designing stabilizing regulators for linear systems subject to control saturations and asymmetric constraints on its increment or rate, using reduced dimension linear matrix inequalities (LMIs) developed on a reduced-order state space. Compared with previous approaches, the proposed technique is valid for asymmetric constraints on the increment or rate of the control while the computing time is improved by resolving LMIs of reduced dimensions     

Internet/Intranet系统设计中的安全对策

本文对网络安全进行技术分析，从不同角度阐述网络安全的隐患，在设计中采用相应对策，确保Internet/Intranet网络安全运行。