首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
用DDFS技术提供参考信号,以快速模拟开关取代乘法器件,加上四阶巴特渥斯低通滤波器构成了本选频电平表的混频环节。对中频信号采样转换,由DFT分析直接得出信号幅值,由于在DFT分析中采用了布来克曼-哈利斯三项系数窗,从而获得了带宽约为2Hz的窄带滤波效果。  相似文献   

2.
用DDFS技术提供参考信号,以快速模拟开关取代乘法器件,加上四阶巴特渥斯通滤波器构成了本选频电平表的混频环节。对中频信号采样转换,由DFT分析直接得出信号幅值,由于在DFT分析中采用了布来克曼-哈利斯三项系数窗,大而获得了带宽约为2Hz的窄带滤波效果。  相似文献   

3.
非对称数字用户环路(ADSL)选择离散多音频DMT(Discrele Multitone)为系统的传输码,针对DMT的IFFT/FFT单元计算量大、硬件要求高等特点,本文提出了一种降低IFFT/FFT单元复杂度的CR DMT(Complexity Reduced DMT)结构。与传统的DMT及一些改进方案相比较,该结构具有原理简单,易于实用等特点。  相似文献   

4.
二维实值与复值离散GABOR变换的比较   总被引:1,自引:1,他引:0  
本文介绍了作者曾提出的快速二维实值离散 Gabor变换(RDGT)方法,以及 RDGT系数与复值离散 Gabor变换(CDGT)系数之间的关系,并在不同的等效窗宽条件下,通过对图像的二维RDGT系数 与二维CDGT系数熵的比较,指出二维RDGT比二维CDGT更适合于图像的压缩。  相似文献   

5.
陶亮  解小平 《现代计算机》2000,(103):9-11,14
本文介绍了作者曾提出的快速二维实值离散Gabor变换(RDGT)方法,以及RDGT系数与复值离散Gabor变换(CDGT)系数之间的关系,并在不同的等效窗宽条件下,通过对图像的二维RDGT系数与二维CDGT系数熵的比较,指出二维RDGT比二维CDGT更适合于图像的压缩。  相似文献   

6.
试析Microsoft文件系统的关键数据结构   总被引:1,自引:0,他引:1  
本文分析了DOS的FAT/FDT、Windows95的VFAT、Windows和OS/W的HPFS的结构,并给出它们各自的优缺点。  相似文献   

7.
DTMF是音频电话中的拨号信号,广泛运用于电话信息查询系统、电子邮件系统等交互式的控制应用中。介绍了基于ADSP21xx系列DSP芯片的DTMF软件检测方法,解决了采用专用芯片所带来的不足之处,使得DTMF检测变为迅速、灵活和准确。  相似文献   

8.
一个超高速FFT阵列式计算结构设计方案   总被引:1,自引:0,他引:1  
本文分析了CORDIC算法和FFT算法的在内在联系,设计了基于CORDIC算法的四个蝶形运算器芯片,并在此基础上构成了FFT阵列式计算结构,N=2^m点的FFT计算速度可达到微秒级,有很好的性能人格比,在超高速实时信号处理中有广阔的应用前景。  相似文献   

9.
产品超市     
坐在18.1英寸的康柏TFT8000LCD前,你会感到它大得像是用一块广告牌替代了显示器。唯一使人担心的是康柏TFT8000可能超过你的预算,目前市价为3200美元,这简直是个天价。作为1280×1024分辨率的显示器,康柏TFT8000很容易把分辨率调整到VGA模式。和其他TFTLCD相比,康柏TFT8000的放缩功能已经达到了一个很高的水准。只是有一个问题,在标准的低显示模式下长宽比是4:3,但是在1280×1024分辨率下是5:4,因此在低分辨率下物体看起来在纵向上被拉"瘦"了。康伯TFT8…  相似文献   

10.
介绍了一种AutoCAD与FoxBASE数据共享的思路,给出了DBF文件或TXT文件转换为DWG文件格式的一种手段。采用文件方法可以做到AutoCAD下数据的一次性录入,多次使用。  相似文献   

11.
Many software engineering applications require points-to analysis. These client applications range from optimizing compilers to integrated program development environments (IDEs) and from testing environments to reverse-engineering tools. Moreover, software engineering applications used in an edit-compile cycle need points-to analysis to be fast and precise.In this article, we present a new context- and flow-sensitive approach to points-to analysis where calling contexts are distinguished by the points-to sets analyzed for their call target expressions. Compared to other well-known context-sensitive techniques it is faster in practice, on average, twice as fast as the call string approach and by an order of magnitude faster than the object-sensitive technique. In fact, it shows to be only marginally slower than a context-insensitive baseline analysis. At the same time, it provides higher precision than the call string technique and is similar in precision to the object-sensitive technique. We confirm these statements with experiments using a number of abstract precision metrics and a concrete client application: escape analysis.  相似文献   

12.
源代码分析技术对于软件安全缺陷分析是一项非常重要的手段.分析了软件源代码分析工具的技术手段和发展过程,最后对源代码分析的理论和实践进行了分析总结.  相似文献   

13.
别名分析对于数据流分析、程序优化和分析工具的实现非常重要.文章提出了一种需求驱动,流非敏感的分析算法来解决指针别名问题.通过构造程序表达式图(PEG)把指针别名问题转化成判断两个指针节点是否是联通的问题,它不同于传统的别名分析方法,它不需要构造别名集合和对其求交集,所以提高了分析指针别名的效率.  相似文献   

14.
M. H. Williams 《Software》1982,12(5):487-491
The researcher who knows little about computers but wants to conduct a survey and analyse the results by computer can land himself in some difficulty if he does not appreciate some of the problems of computerization. This paper describes a system which is designed to aid such a person by providing assistance with the design of the questionnaire, the capturing of the data and the final analyses.  相似文献   

15.
《Ergonomics》2012,55(11):1787-1800
Abstract

The role of cognitively oriented tasks in the workplace continues to increase as automation of physical task components advances. Difficulties in automating the operator's cognitive processes have placed a renewed emphasis on the human component in advanced manufacturing systems. While traditional task analysis techniques have made significant contributions to improving productivity when important task elements are visually observable, their focus on manual task procedures make them less effective for cognitively oriented activities. This research has made a first attempt at integrating techniques from several disciplines to develop a cognitive task analysis methodology. The utility of this combined approach is examined for a new system being tested in the United States Postal Service. This task requires operators to encode, via a keyboard, addresses presented on a video display terminal. Results support the hypothesis that, for cognitively oriented tasks, a consensus based analysis technique (the Position Analysis Questionnaire) can be significantly improved by including data from task analysis provided the methodology is suitable for identifying non-physical task components.  相似文献   

16.
The size of today’s programs continues to grow, as does the number of bugs they contain. Testing alone is rarely able to flush out all bugs, and many lurk in difficult-to-test corner cases. An important alternative is static analysis, in which correctness properties of a program are checked without running it. While it cannot catch all errors, static analysis can catch many subtle problems that testing would miss.We propose a new space of abstractions for pointer analysis—an important component of static analysis for C and similar languages. We identify two main components of any abstraction—how to model statement order and how to model conditionals, then present a new model of programs that enables us to explore different abstractions in this space. Our assign-fetch graph represents reads and writes to memory instead of traditional points-to relations and leads to concise function summaries that can be used in any context. Its flexibility supports many new analysis techniques with different trade-offs between precision and speed.We present the details of our abstraction space, explain where existing algorithms fit, describe a variety of new analysis algorithms based on our assign-fetch graphs, and finally present experimental results that show our flow-aware abstraction for statement ordering both runs faster and produces more precise results than traditional flow-insensitive analysis.  相似文献   

17.
重点选取了15个副省级城市的第一产业比重、人口密度、人均绿地、园林面积、医院数目,市政建设面积、地方财政税收等42个指标,使用SPSS作为计算工具,使用因子分析方法简化评价指标,计算相关系数矩阵,判别因子分析可行性,利用主成分分析法求因子载荷,将因子进行旋转得出更有实际意义的因子解释,并计算因子得分,利用该结果计算Mi...  相似文献   

18.
一种全局数据流分析的新方法   总被引:1,自引:0,他引:1  
  相似文献   

19.
Cost analysis statically approximates the cost of programs in terms of their input data size. This paper presents, to the best of our knowledge, the first approach to the automatic cost analysis of object-oriented bytecode programs. In languages such as Java and C#, analyzing bytecode has a much wider application area than analyzing source code since the latter is often not available. Cost analysis in this context has to consider, among others, dynamic dispatch, jumps, the operand stack, and the heap. Our method takes a bytecode program and a cost model specifying the resource of interest, and generates cost relations which approximate the execution cost of the program with respect to such resource. We report on COSTA, an implementation for Java bytecode which can obtain upper bounds on cost for a large class of programs and complexity classes. Our basic techniques can be directly applied to infer cost relations for other object-oriented imperative languages, not necessarily in bytecode form.  相似文献   

20.
易定 《微机发展》2006,16(9):112-114
数据分析是从海量数据中发现隐含信息或知识的过程。基于一个公安破案辅助数据分析系统,深入研究数据分析任务的需求与实现,提出首先规划分析思路、细化分析功能,然后用多视角数据透视和智能分析两种手段,从微观与宏观、定量与定性等不同角度互为补充地使系统具有完备的分析功能。该研究对如何开发具有实用价值的数据分析系统有普遍的指导意义。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号