基于不完全信道状态信息的预编码算法

针对下行多用户多输入多输出中继系统,提出一种考虑信道估计误差和天线相关的线性预编码算法。在发射端和中继端功率约束条件下,根据最小均方误差准则设计代价函数,通过理论推导求得中继端和发射端的预编码矩阵。接收端的各个用户之间相互独立时,接收端的处理矩阵为对角矩阵,通过直接求导法得到接收端预处理矩阵的闭式解,并设计迭代法联合优化预编码矩阵和接收端的处理矩阵。数值仿真结果表明,与未综合考虑各端口的预编码算法相比,该算法能降低系统的误码率。     

手机将可玩次世代级别大作

今年游戏开发者大会期间公布的OnLive在线游戏点播服务通过云计算的原理,将游戏画面的处理任务交给远方的处理器,通过网络向接收端传输画面,只要网速够快,接收端只要能播放网络视频,就可以玩到有顶级画面质量的游戏。这种技术对用户的硬件配置要求降到最低,理论上即使是手机也可以享受与次世代主机一样出色的画面。     

一种卫星网络中基于分层传输的混合ARQ机制

由于卫星链路的长时延和接收端异质性的特点,混合ARQ机制并不适合直接应用于卫星网络。为了适应卫星网络的特点,设计了一种新的混合ARQ机制。RSE编码被用来恢复接收端的错误。发送端利用接收端的反馈信息对接收端分类,根据分类的结果将补包数据分层传输。接收端选择加入一个或多个发送层次以接收足够数量的冗余数据。此时,接收端可以快速接收到其需要的补包数据,从而避免了由于接收端异质性而引起的系统效率降低。仿真结果表明,改进的混合ARQ机制相比于传统的可靠性保证机制具有更好的吞吐效率和网络可扩展性。     

基于UDP协议的视频图像传输研究与实现

根据视频图像传输的要求,扩展了UDP协议,定义了包头结构,在发送端对传输进行光滑化处理,在接收端预留一个适当的缓冲区以存储期望包到达之前的数据,添加了流量控制、失序和包丢失处理机制,从而保证了视频图像传输的有序性和正确性。     

基于Walnut Street修正模型的短波信道仿真算法

传统短波信道Watterson模型只能模拟信道短期变化规律。为模拟短波信道在各种长度时间段内的变化,针对短波信道接收端信噪比统计特性,提出了一种基于信噪比重放的短波信道仿真算法。该算法以Walnut Street信道模型为基础,通过对实际观测数据进行分析处理,建立接收端信噪比变化的中期和长期变化统计模型,联合Watterson模型实现信道模拟。仿真结果表明,该算法可反映实际信噪比变化规律,为短波网络仿真提供精确的信道质量模拟。     

基于全同态MAC的消息认证算法设计

针对通信信道中数据传输的安全性和认证问题,通过对全同态加密和消息认证码(Message Authentication Code,MAC)算法的研究,提出一种基于全同态MAC的消息认证算法设计方案。该方案首先在接收端对消息进行全同态加密,结合MD5算法对加密后的数据进行扰乱处理,将处理后的数据在信道中传输。然后,在接收端检测消息在传输信道中是否被篡改,再对数据执行全同态解密,进而确保消息传输的可靠性。最后,在SMIC 65 nm工艺下完成硬件设计,DC综合后电路面积为21 911μm~2,在1.2 V电压下最高工作频率可达到204 MHz,功耗为5.73 m W。     

32通道无线表面肌电和加速度信号采集系统设计

为满足对肌电信号采集系统无创、便携、更大传输数据量的需求。本文实现了基于蓝牙无线传输协议的32通道肌电和加速度信号采集系统。系统发送端由4组8通道信号采集发送模块组成,完成对表面肌电信号和加速度信号的采集、处理及发送;接收端采用FPGA管理4组蓝牙接收端进行一对一数据接收,同时完成对数据进行统一打包处理并发送到PC机进行数据存储、数据处理及信号波形显示。经测试,本系统一次充电可持续工作6小时,无线通信距离12m,信号噪声比高于70dB。测试结果表明,本系统可应用于手势识别、健康监护等领域。     

北斗卫星导航接收端抗干扰性能测试系统构建方法研究

由于空间电磁环境日益复杂,卫星导航接收端抗干扰性能成为北斗用户密切关注的问题。为了对接收端抗干扰性能进行测试,提出一种卫星导航接收端抗干扰性能测试系统构建方法。采用数字式仿真技术以及基于脚本的仪表驱动技术,结合信号源模拟设备、耦合器、微波暗室等构建半实物仿真系统,实现了对卫星导航接收端抗干扰性能的测试。使用接收端有效载噪比作为抗干扰性能指标,通过调节干扰信号发射端输出功率进行仿真。仿真结果表明,该系统能够得到干信比与有效载噪比的关系曲线,从而为北斗用户接收端抗干扰性能测试提供较大的参考与使用价值。     

基于C8051F310的电力机车电机无线监测系统

本文利用C8051F310单片机、RF收发模块和单总线温度传感器设计了一个服务于电力机车的电机状态监测系统。系统利用单片机片内AD器件和单总线温度传感器来完成电机参数的数据采集。数据暂时存放在片内开辟的缓冲区,之后通过SPI接口发送给RF收发模块并发射至接收端,接收端通过一块相同的RF模块接收数据并通过串口将数据传至上位机进行后端处理。     

协调路由和资源预留机制的实时多播协议

流媒体应用程序必然涉及网络上的实时任务处理。在一般情况下每个数据流都有很多接收端,因此确保网络传输的时间限制的多播资源预留协议非常必要。提出了一个针对一对多,即一个发送端、多个接收端的实时多播协议,因为未涉及到多对多的情况,故称为简单实时多播协议。协议通过将路由机制和资源预留机制用一个通用接口协调起来,提供了一个更为灵活的连接建立方式,并同其它已存在的流媒体协议如RSVP、ST-II进行比较和分析。     

3D模型LOD算法的研究及其OpenGL实现

3D模型LOD技术是计算机图形学的一个重要研究课题，简述了3D模型LOD技术的基本原理并分析和探讨了各类LOD算法。为了克服LOD算法在使用中的局限性，提出了一种3D模型LOD算法，并通过OpenGL编程进行了实现，运行的结果表明此3D模型LOD算法是可行和高效的。     

A fixed-point DSP for graphics engines

The use of the 16-bit ADSP-2100 digital signal microprocessor as a fixed-point, low-end graphics engine for applications such as video games and small computer graphics packages is examined. It serves as the basis for a complete, hardware-oriented approach to performing graphics operations on a 3-D database. Normalization and formatting are performed to avoid overflow and preserve data formats through the transformation operation. Data structures that facilitate object rendering through the Bresenham line-segment drawing algorithm are used. A 3×3 rotation matrix is derived for this application, and the means for implementing translation, scaling, perspective, and zooming are described     

Development and application of a three-dimensional artificial visual system

A three-dimensional artificial visual system has been developed to aid in the analysis of 3-D fluorescence images of smooth muscle cells. The system consists of three sets of 3-D spatial filters that decompose the image to enable a simple recombination algorithm to locate the discrete bodies of protein concentration in a cell, classify the concentration bodies as globular or oval, and determine the 3-D orientation of the oval bodies. A graphic model of the protein concentration is created from the data provided by the artificial visual system. Patterns of organization in the distribution of the protein bodies are investigated using an interactive graphics system.     

运动人体三维测力分析系统的设计与实现

运动人体三维测力分析系统(MBFMAS)采用并行数据采集方法,解决了三维测力平台测试过程中,测试数据的丢失问题,提高了三维测力平台的测试精度。该系统可完成数据采集,数据管理,图形显示,数据分析等功能,系统采用中文界面设计,操作简便、图形显示分辨率高,并具有监控多台三维测力平台和高速录像同步测试功能。     

Segmentation-Based View-Dependent 3-D Graphics Model Transmission

For wireless network based graphics applications, a key challenge is how to efficiently transmit complex 3-D models over bandwidth-limited wireless channels. Most existing 3-D mesh transmission systems do not consider such a view-dependent delivery issue, and thus transmit unnecessary portions of 3-D mesh models, which leads to the waste in precious wireless network bandwidth. In this paper, we propose a novel view-dependent 3-D model transmission scheme, where a 3-D model is partitioned into a number of segments, each segment is then independently coded using the MPEG-4 3DMC coding algorithm, and finally only the visible segments are selected and delivered to the client. Moreover, we also propose analytical models to find the optimal number of segments so as to minimize the average transmission size. Simulation results show that such a view-based 3-D model transmission is able to substantially save the transmission bandwidth and therefore has a significant impact on wireless graphics applications.     

The Systolic Pixel: A Visible Surface Algorithm for VLSI.

The Systolic Pixel or Spixel is a novel architecture for an intelligent pixel-based graphics database for geometric-solid models. An algorithm is described which performs visible surface calculations for any complexity of coloured 3-dimensional (3-D) surface and which structures geometric-solid model data in a natural way. The algorithm/architecture of the spixel features a simple set of priority rules acting upon data in nearest neighbour locations and a simple set of movement rules of data to nearest neighbour locations. The spixel is constructed out of identical functional units. These features are attractive for an implementation of the algorithm in Very Large Scale Integration (VLSI).     

基于3-D IFS理论的自然景观模拟

1 引言数学家Mandelbrot在20世纪70年代所提出的分形几何,给出一种描述具有随机形态特征及无穷细节的自然现象的全新的数学工具。此后,以Hutchinson和Barnsley等的工作为基础,人们注意到许多分形集都可以用IFS递归构造出来,并可以用来逼近任意现实对象,可见分形技术是计算机真实感几何造型方面十分活跃且有效的方法和手段。     

Interpretive Tools for 3-D Structural Geological Modeling Part I: Bézier-Based Curves, Ribbons and Grip Frames

Interpreting the geometry of geological objects is a standard activity of field-based geologists. We present new graphics tools that will aid in extending this activity from 2-D geological mapping into a 3-D environment. Much of the existing 3-D geological modeling software supports the construction of objects with the input of dense control data. However, for regional mapping and near mine exploration work, sparse data is the norm. Tools are required therefore, which give the expert interpreter full control of the graphics objects, while at the same time constraining interpretations to specific control data from field observations. We present the initial results of a software design and programming project for the visualization of complex regional scale geologic objects using Bézier-based graphics tools that are optimized for sparse data interpretation. We also introduce the concept of a structural ribbon, which is a 3-D extended map trace, along with methods for the optimization of surface construction using graphical grip frames.     

Three-dimensional reconstruction of human limbs from tomographic views

The recently developed medical imaging technique of tomography can be used with amazing success to learn about the interior of a human body. Each tomograph, however, is limited to only one section of the specific human limb. A series of tomographs taken at irregular intervals and various angles would provide three-dimensional information of the interior of the limb. Currently available 3-D surface display algorithms have limitations, particularly when applied to clinically important image data requiring fast and flexible interactive analysis. In addition to the problem of computation time is the cost of specialized hardware. A new algorithm has been designed for use with three-dimensional medical images which attempts to overcome these limitations. A computer graphics system is described which reconstructs three-dimensional images from tomographic sectional data. This 3-D surface algorithm can be exploited in planning reconstructive bone surgery. An example which illustrates the versatility and speed of the new algorithm is presented.     

仓储仿真三维图元管理平台

在仓储仿真项目的开发中,图元的创建和三维场景的布置是重要的步骤。为了简化仓储仿真项目的开发,提出一种仓储三维仿真图元管理的平台方案。该平台模型由4个关键模块组成。并在WPF下实现了关键模块,结果表明采用该平台的相应模块能够实现仿真图元对象的快速创建、仿真图元的高效管理,方便地为开发基于WPF平台的仓储仿真项目提供合适的图元对象。因此该平台能够简化仓储仿真项目的开发步骤。节省开发时间。