基于包围盒的可变形物体碰撞检测算法

包围盒方法是当前虚拟现实技术中应用较广泛的碰撞检测算法。文中重点对包围盒算法中的轴向包围盒(AABB)法、方向包围盒(OBB)法和固定方向包包围盒(k-dops)法,从包围盒的构建、相交检测等方面做了详细分析,并从构造难度、相交测试复杂度、紧密性、变形体碰撞适用度、检测精度和应用范围等6个方面,对这3类方法进行了比较。根据比较结果,在应用中可选择性使用3类方法。     

基于包围盒约束光谱聚类的红外目标识别算法

在红外成像过程中,目标边缘模糊化是影响红外目标识别效果的关键因素,也是红外目标识别算法的研究重点,故在光谱图像中合理补偿目标几何特征信息成为研究热点之一。结合包含目标几何特征信息的包围盒作为约束条件,对红外光谱图像进行分层限定滤波,降低原有图像数据中目标几何外形数据的丢失,提高目标可识别性。设计了在包围盒约束条件下的光谱聚类算法,设置参数η表征待测军用车辆目标的几何信息,设置参数m表征待测军用车辆目标的光谱特征信息。实验采用TEL-1000-MW型红外成像光谱仪获取多光谱图像,通过改变m和η值调整光谱特征值个数与包围盒范围,从而获得不同的目标识别图像。并与传统方法对同一幅红外目标图像的识别效果相比较,结果发现采用包围盒约束的待测目标图像几何边界信息保留效果明显优于传统方法,当m=10、η=0.7时,红外图像的目标识别效果最好,同时算法收敛速度也最优。由此可见,该算法在提高红外目标识别能力、避免误判伪目标和漏检目标方面具有很高的实用价值。     

三维视景仿真的包围盒碰撞检测算法优化

提出了从全局搜索过程和局部搜索过程两方面来改进基于AABB包围盒的三维视景仿真碰撞检测算法的方法.在全局搜索过程中,利用帧与帧之间的关联特性,对检测算法进行优化,记录当前对象的碰撞信息以供下一帧的碰撞检测使用.在局部搜索过程中,介绍了基于垂线的三角形与包围盒相交测试算法.实验结果证明,算法加快了碰撞检测时间,提升了检测...     

一种快速混合碰撞检测算法研究

为提高虚拟环境的临境感和真实感,对其中的关键技术碰撞检测进行研究,提出了一种快速碰撞检测算法。复合层次包围盒碰撞检测能发挥不同类型包围盒碰撞检测的优势进行检测,但不能充分利用当前图形硬件的快速并行计算的优势;基于流的碰撞检测算法可充分发挥后者的优势,但会造成许多冗余检测。提出的新算法将复合层次包围盒碰撞检测算法与基于流的碰撞检测算法相结合：在预处理阶段构造复合层次包围盒树,然后利用复合层次包围盒碰撞检测算法进行初步检测快速排除不可能相交的物体对,接着利用基于流的碰撞检测算法对得到的碰撞子集进行精确求交,得到碰撞检测的结果。实验通过与RAPID和原始的基于流的碰撞检测算法进行比较,证明该算法能有效进行实时碰撞检测。     

一种面向虚拟维修的快速碰撞检测方法

针对虚拟维修中碰撞检测的自身特点,提出一种基于空间均匀网格的层次包围盒算法,该算法首先使用空间划分剔除不必要检测的物体,再通过层次包围盒法准确地找出相交的物体。文中给出了层次包围树的构建方法、空间划分方法,并且采用哈希数据结构和同步深度遍历方法加速了检测的速度。最后在CATIA/CAA平台上实现了该算法,验证了算法的实时性能。     

基于有向包围盒的尺度点云配准算法

为了提高激光点云的配准精度和效率,解决两片点云之间存在尺度变换的配准问题,提出了一种基于有向包围盒的尺度点云配准算法.首先,分别生成两片点云的空间有向包围盒,利用两个包围盒对应边的比值计算尺度因子.然后,将目标点云包围盒进行尺度放缩,再利用包围盒对应顶点的关系计算旋转矩阵.同时,引入点云的单位向量和,以单位向量和之间余...     

统计MIMO雷达多目标定位

文中探讨了统计MIMO雷达进行多目标定位的方法,针对于目标相交或相近的情况下,在基于椭圆模型搜索的基础上,引入一个时间元素,并结合拓展卡尔曼滤波算法实现了统计MIMO雷达多目标定位,仿真结果表明扩展卡尔曼滤波算法可以实现对多个目标的准确定位,即使是目标相交或靠近时也可以实现准确定位。     

红外图像光学特征仿真系统的研究

文章从图像处理仿真系统出发,首先介绍了图像处理对仿真系统的要求,接着对红外图像处理仿真系统的构成进行了分析,然后利用理论模型对仿真系统的光学特性仿真部分,也即目标与背景的红外辐射特征进行了计算,生成了目标与背景的红外热图像。试验结果表明,本文提出的红外图像仿真系统能满足红外目标识别算法评价的要求,有利于提高红外目标识别算法研究的速度和识别算法的稳定性。     

改进人工势场法的机械臂避障路径规划研究

文章针对人工势场法可能会进入局部极小这一缺陷,通过添加虚拟目标点来改进人工势场法。该方法可以让机械臂逃离局部极小点,实现机械臂的避障路径规划。文章使用DH模型对机械臂进行正逆运动学分析,使用椭球包围盒进行机械臂碰撞检测,通过建立目标点,机械臂的引力场和障碍物对机械臂的斥力场,再搜索势函数的下降方向,实现机械臂的路径规划。最后仿真结果验证,使用虚拟目标点的人工势场法可以快速有效地进行避障规划路径。     

目标与背景的红外辐射特性仿真方法

基于红外辐射理论,综合考虑自身辐射、反射辐射、大气长波辐射等因素,研究了目标的红外辐射特性仿真方法,编制了目标红外辐射仿真软件。以某钢板为例,建立了目标的仿真计算模型,确定了目标表面的边界条件,计算了目标表面的温度场分布,将仿真计算与试验测量的钢板表面温度数据进行了对比,结果显示:仿真计算的平均误差在1.5 ℃以下,验证了仿真方法的正确性,并在此基础上仿真计算了不同时刻目标的红外辐射特征分布,证明了红外仿真方法的合理性,为车辆与复杂背景的红外仿真计算奠定了基础。     

Design of multichip modules

The process and pitfalls of multichip module (MCM) design, including the constraints, tradeoffs, figures of merit, and considerations which make MCM design a unique interdisciplinary challenge are discussed. The MCM must provide the proper operating environment for the chips it contains. It must also fit the constraints of the system in which it is contained. It must be manufacturable, testable, and repairable. The many aspects of MCM design are described, starting with system benefits, then system and MCM partitioning, chip environment, system constraints, and infrastructure/manufacturing issues     

Max-SINR ISI/ICI-Shaping Multicarrier Communication Over the Doubly Dispersive Channel

For communication over doubly dispersive channels, we consider the design of multicarrier modulation (MCM) schemes based on time-frequency shifts of prototype pulses. We consider the case where the receiver knows the channel state and the transmitter knows the channel statistics (e.g., delay spread and Doppler spread) but not the channel state. Previous work has examined MCM pulses designed for suppression of inter-symbol/inter-carrier interference (ISI/ICI) subject to orthogonal or biorthogonal constraints. In doubly dispersive channels, however, complete suppression of ISI/ICI is impossible, and the ISI/ICI pattern generated by these (bi)orthogonal schemes can be difficult to equalize, especially when operating at high bandwidth efficiency. We propose a different approach to MCM pulse design, whereby a limited expanse of ISI/ICI is tolerated in modulation/demodulation and treated near-optimally by a downstream equalizer. Specifically, we propose MCM pulse designs that maximize a signal-to-interference-plus-noise ratio (SINR) which suppresses ISI/ICI outside a target pattern. In addition, we propose two low-complexity turbo equalizers, based on minimum mean-squared error and maximum likelihood criteria, respectively, that leverage the structure of the target ISI/ICI pattern. The resulting system exhibits an excellent combination of low complexity, low bit-error rate, and high spectral efficiency.     

两种改进的适用于多目标情况的恒虚警检测算法

本文基于筛选平均(CM)和无偏筛选平均(UCM)提出了两种改进的恒虚警检测器MCM-CFAR和MUCM-CFAR,并应用了何友(1994)提出的自动筛选技术.在Swerling Ⅱ型目标假设下,并考虑瑞利分布杂波和单脉冲检测情形,本文推导出了MCM-CFAR和MUCM-CFAR检测器的Pfa、Pd和平均判决门限(ADT)的解析表达式,并与其它方案进行了比较.分析结果表明,它们在均匀背景和多目标环境中的性能均明显优于GOSCA和OS;当IL=4,IR=2时,MCM-CFAR比OS改善了2dB,MUCM-CFAR也比OS改善了1.5dB;MCM的性能略优于CM,MUCM与UCM接近,但它们的样本排序时间不足CM、UCM和OS的一半,便于工程实现.     

高温超导多芯片组件

超导多芯片组件被誉为继高温超导之后 ,超导研究最大的技术革命。采用超导材料作互连线 ,是解决芯片间互连瓶颈的有效技术途径。它可保证电子系统进一步高速化、小型化和宽带化。本文阐述了高温超导 MCM的研究现状、存在的问题及其发展前景。     

A 1.8 V 828 μW 80 dB digital MEMS microphone

A single-package digital MEMS Capacitive Microphone (MCM) system is presented. The system consists of a MCM, which is wire-bonded with its readout interface (RI). The MCM sensor is fabricated using a combination of surface and bulk micromachining, employing diaphragm-stiffening to achieve piston-like diaphragm-movement and attaining required sensitivity with a smaller diaphragm-area. The RI is designed in 0.35 μm CMOS and it consists of a preamplifier (PAMP), a sigma-delta modulator (SDM), integrated biasing and digital control, converting the MCM capacitive variations into a single-bit over-sampled digital bitstream. The PAMP employs a two-terminal bootstrapped source-follower buffer to make the readout insensitive to the MCM parasitics, subsequently feeding a third-order single-loop single-bit modulator running at 2.5 MHz. The electrical measurements of the standalone RI demonstrate 55 dB A-weighted @ 1 Pa SNDR at the analog PAMP output and 80 dB A-weighted dynamic-range at the digital output, which corresponds to a conversion range from 40 to 120 dB SPL. The SNDR for acoustic measurements is 33 dB A-weighted @ 1 Pa, limited by the higher MCM thermal noise floor and reduced sensitivity (−53 dB V @ 1 Pa). The frequency characterization of the system for the complete audio-band demonstrates the effect of the system package towards higher frequencies (>9 kHz), giving rise to Helmholtz resonance, and reduction in sensitivity for low-frequencies (<400 Hz) because of acoustic short-circuiting inside the MCM due to flow-by slots. The complete system consumes 460 μA of total current for a 1.8 V single-supply. The total system dimensions are 4.5 × 2 mm² (excluding the package), demonstrating the viability of a low-area, low-power and high dynamic-range implementation of digital MCM.     

抑制MCM互连线反射的终端匹配方法

针对MCM互连,分析了反射噪声产生的原因及其对电路性能的影响。基于终端匹配理论研究了简单并联端接、戴维南端接和RC端接等几种终端匹配方法。选取MCM的典型互连参数和互连线的等效模型,使用PSPICE对三种不同的终端匹配方法进行仿真,分析了三种终端匹配方法各自的特点。在时钟频率较高的MCM中,可采用终端匹配技术来有效的抑制互连线上的反射噪声。     

Two novel nonlinear companding schemes with iterative receiver to reduce PAPR in multi-carrier modulation systems

Companding transform is an efficient and simple method to reduce the Peak-to-Average Power Ratio (PAPR) for Multi-Carrier Modulation (MCM) systems. But if the MCM signal is only simply operated by inverse companding transform at the receiver, the resultant spectrum may exhibit severe in-band and out-of-band radiation of the distortion components, and considerable peak regrowth by excessive channel noises etc. In order to prevent these problems from occurring, in this paper, two novel nonlinear companding schemes with a iterative receiver are proposed to reduce the PAPR. By transforming the amplitude or power of the original MCM signals into uniform distributed signals, the novel schemes can effectively reduce PAPR for different modulation formats and sub-carrier sizes. Despite moderate complexity increasing at the receiver, but it is especially suitable to be combined with iterative channel estimation. Computer simulation results show that the proposed schemes can offer good system performances without any bandwidth expansion.     

On the Nonlinear Companding Transform for Reduction in PAPR of MCM Signals

In this paper, we provide the design criteria of the nonlinear companding transforms for reduction in peak-to-average power ratio (PAPR) of multi-carrier modulation (MCM) signals, which can enable the original MCM signals to be transformed into the desirable distribution. As examples, some novel nonlinear companding transforms have been proposed to transform the amplitude or power of the original MCM signals into uniform distribution, which can effectively reduce the PAPR for different modulation formats and subcarrier sizes without any complexity increase and bandwidth expansion. It has been shown by computer simulations that the proposed schemes can significantly improve the performance of MCM systems including bit-error-rate and PAPR reduction.     

Fundamentals of MCM Testing and Design-for-Testability

Products motivated by performance-driven and/or density-driven goals often use Multi-Chip Module (MCM) technology, even though it still faces several challenging problems that need to be resolvedbefore it becomes a widely adopted technology. Among its mostchallenging problems is achieving acceptable MCM assembly yieldswhile meeting quality requirements. This problem can be significantlyreduced by adopting adequate MCM test strategies: to guarantee thequality of incoming bare (unpackaged) dies prior to module assembly;to ensure the structural integrity and performance of assembled modules; and to help isolate the defective parts and apply the repair process.This paper describes todays MCM test problems and presents thecorresponding test and design-for-testability (DFT) strategies usedfor bare dies, substrates, and assembled MCMs.     

3-D MCM封装技术及其应用

介绍了超大规模集成电路（VLSI）用的3-D MCM封装技术的最新发展，重点介绍了3-D MCM封装垂直互连工艺，分析了3-D MCM封装技术的硅效率、复杂程度、热处理、互连密度、系统功率与速度等问题，并对3-D MCM封装的应用作了简要说明。