嵌入式系统环形缓冲区快速读写方法的设计与实现

针对常用环形缓冲区读写数据运行效率低的弊端,提出了一种快速读写环形缓冲区数据的方法。在读写缓冲区数据时,通过位与逻辑运算修改读写指针值,利用读写指针的差值作为缓冲区有效数据个数实现环形缓冲区状态判断。通过仿真测试实验和测试数据分析,这种快速读写环形缓冲区的方法可以显著提高系统运行效率。     

缓冲区溢出攻击的检测与防范

缓冲区溢出攻击是最常用的黑客技术之一,攻击者通过向程序的缓冲区写入超出其长度的内容,造成缓冲区的溢出,从而修改栈上的返回地址,在进程调用程序之后跳转到数据段、堆或者栈上执行危险代码,以达到对系统进行攻击的目的。针对这一特征,提出转换返回地址等方法对缓冲区溢出攻击进行防范。     

一种智能录放音系统的设计与实现

介绍一种基于单片机AT89C51及数码语音芯片ISD4004的智能录放音系统的实现方法.通过分析ISD4004的内存管理机制,重点阐述了单片机控制非定长语音分段录音和组合回放技术,并给出了软件设计流程图.     

Solaris系统平台Oracle数据库内存及其相关参数的使用原则

主要介绍了Oracle数据库内存中数据缓冲区,共享池,排序区,日志缓冲区,应用语句解析命中率及等候的监控等方面内容,并引用了具体的例子进行说明,得出了ORACLE数据库系统在实际应用中通过内存优化,可以发挥更大作用的结论.     

基于Windows2000环境下的缓冲区溢出

通过对Windows内存结构及进程空间分配情况的介绍,详细描述了Win2000环境下缓冲区溢出的原理,并提出了预防缓冲区溢出的有效方法。     

Visual Foxpro文献查阅系统的打印功能设计

文献查阅系统能够将检索出来的数据库记录文本以两种方式打印出来,即全文打印和局部文本的屏幕截取打印。在技术上采用面向对象程序设计方法,使用了系统内存变量和置键盘缓冲区命令,使用户操作极为简便。     

Oracle9i数据库性能调优技术应用研究

Oracle9i数据库的性能直接关系到系统的运行效率,文章以本钢电能量计量管理系统Oracle9i数据库的性能调优入手,从Oracle9i数据库内存分配、I/O调整、oracle9i分区技术、正确使用索引的角度出发,论述了影响Oracle数据库性能的因素及其对应的参数,针对这些参数,分别从共享池、数据库高级缓冲区、I/O等调优几个方面,介绍Oracle数据库的性能调优方法。     

在C语言中利用动态结构数组处理学生成绩表

基于C语言中只能定义定长数组,容易造成大量内存资源浪费,影响实际使用的情况。对C语言中的变长数组的定义和使用进行了探索和分析,在此基础上提出了用指针来处理预先不能确定数组大小的可行性,进一步提出了建立动态结构数组来解决学生成绩统计的方法,通过实际编程,解决了这一问题。     

拆半记忆法对最佳适应算法的优化

最佳适应算法(BF)是内存空闲块分配的一种常用算法,现行BF算法的空闲块查询方法不当从而导致工作效率低下.使用拆半法替代原有的BF算法在空闲块查询时所采用的线性顺序比较法,同时增加分配记忆功能,对BF算法进行优化并加强算法功能,从而直接改善内存的分配效率,对提高系统吞吐量起到积极的促进作用.     

宏程序在板类零件中的典型应用

普通数控程序只能指定常量且常量之间不能计算,程序只能顺序执行,不能跳转,不能变化。用户宏程序引进变量及变量之间的计算,允许使用逻辑判断语句,可通过变量来编程,增加程序的通用性和灵活性。     

固定三角形内插入一点的测边网条件式分析

固定三角形内插入一点的测边网,按条件平差法进行平差计算时,可列出图形条件方程式,也可列出固定角条件方程式,文章分析了两种条件式之间的关系,从理论上证明了不同条件式的替代方法,从而使平差计算更为简单.     

Pigeons’ short-term memory for temporal and visual stimuli in delayed matching-to-sample

In the present experiment, we compared directly pigeons’ short-term memory of temporal and visual stimuli in a delayed matching-to-sample task. The sample stimuli consisted of red and green lights presented for 5 and 30 sec, followed by a retention interval and blue and yellow comparisons. For subjects in the visual group, duration was irrelevant and the color of the sample was the conditional cue. For animals in the temporal group, color was irrelevant and duration of the sample was the conditional stimulus. The results showed that acquisition of the matching task was faster and accuracy was higher in the visual than in the temporal group. More importantly, memory of either sample generally declined at a similar rate when the duration of the retention interval was increased and when the intertrial interval was reduced. Taken together, the results indicate that with 1–8-sec retention intervals, short-term memory for temporal stimuli is similar to that found with color-visual samples. The findings are discussed in terms of retrospective and prospective processing.     

A QoS-aware scheduling algorithm for combined-input-crosspoint-queued switch

In this paper, we study the quality of service requirement and guaranteed-rate scheduling problem for combined-input-crosspoint-queued (CICQ) switches. Using crosspoint buffers between input queues and output ports, the input and output scheduling can be decoupled in CICQ switches. Here we propose a new guaranteed-rate scheduling algorithm which is divided seperately into input and output scheduling. Simulation results show that our algorithm can perform better than existing scheduling schemes in both packet loss and jitter control.     

Android移动通信序列化协议研究

Protocol buffers协议是Google公司开发的高效数据序列化协议.它具有与平台无关、语言无关、体积小、高性能等特点,在一些对数据实时性要求比较高的场合,XML已不能完全胜任,基于股票数据的动态变化特性,以Android系统为平台,对于XML和Protocol buffers协议从不同方面进行了比较研究,最后得出Protocol buffers在某些应用场景下代替XML可以获得更佳效能的结论.     

应用VQ-HMM的汉语数码语音识别

提出了一种新的语音识别方法,该方法综合了VQ和离散HMM算法,在每个状态通过用矢量量化误差值取代传统的HMM输出概率值来建立VQ-HMM.介绍了VQ-HMM,并通过非特定人汉语数码语音识别实验对其识别性能与传统的HMM作了相应的比较.实验结果表明该方法识别效果优于传统的HMM.,In this paper, a new speech recognition method was proposed, which integrated a VQ-distortion measure and a discrete HMM. The VQ-HMM uses a VQ-distortion measure at each state instead of a discrete output probability used by a discrete HMM. The VQ-HMM is described, and its speech recognition performance is compared with the conventional HMMs through the experiments on speaker-independent Chinese spoken digit recognition. The comparisons confirm that the new method over-performed traditional HMMs.     

中国研究与开发的国际比较

主要从中国研究与开发（R＆D）的投入、产出以及绩效三个方面来和世界发达国家进行比较。其中,投入部分包括经费和人员的投入;产出部分则主要选取了科技论文发表数量和专利产出数目两个指标;绩效对比则按照每单位投入的平均产出来衡量。通过国际比较,可以清楚地认识到目前中国的研发实力和发达国家的差距,并分析其中的原因,找出相应对策。     

稳功率氦氖激光器电源的研制

一种新型氦氖激光器电源以直流12V输入,并采用开关电源逆变、倍压整流等技术;摒弃了传统的大电阻恒流的方式,采用了负反馈电路控制电流,减少了功耗,且稳流精度高于2％;还增加了稳功率电路,稳功率精度可达3％以上。     

Common coding in pigeons: Partial versus total reversals of one-to-many conditional discriminations

Common coding in pigeons was examined using a delayed conditional discrimination in which each sample stimulus was associated with two different comparison stimuli (one-to-many mapping). In Experiment 1, pigeons matched circle and dot samples to red and green hues and vertical and horizontal line orientations. In Experiment 2, the samples were red and green and the comparisons were vertical and horizontal spatial positions (up vs. down and left vs. right). Following acquisition to high levels of accuracy in each experiment, the associations between the samples and either both sets or only one set of comparisons were reversed. Pigeons learned the total reversals faster than the partial reversals. These results suggest that when different comparisons are associated with a common sample, they may become functionally equivalent.     

Determinants of participation and expenditure patterns of private tuition received by primary school students in Penang,Malaysia: an exploratory study

In this exploratory study, the censored Tobit model is applied on primary data collected amongst parents of primary school students in Penang, Malaysia to examine the determinants of participation and expenditures on private tuition (PT). Results of the marginal effects indicate that socio-demographic characteristics – ethnicity, household income, level of schooling, and marital status – affect the probability of participation and its corresponding conditional (amongst those whose spending is positive) and unconditional (overall) expenditures. Specifically, compared to ethnic Malays, households of Chinese and Indian descent are more likely to send their children to PT, whilst spending more on conditional and unconditional expenditures, ceteris paribus. Low-income households have a lower likelihood to enrol their children in PT classes and spend less on conditional and unconditional expenditures than higher income households. Upper primary students are more likely to attend PT and spend more on conditional and unconditional expenditures than lower primary students. Single-parent households spend more on conditional and unconditional expenditures than households where both parents are together, all else equal. Based on these findings, several observations in terms of comparisons to other studies and policy implications are noted vis-à-vis the demand for PT amongst primary school students.     

带缓冲器的多入口、多出口串行生产线的无阻塞最优控制

本文讨论了带缓冲器的串行生产线的无阻塞最优控制问题,给出了多入口、多出口情况下串行生产线的加工状态方程及其最化控制。