合成孔径雷达原始数据量化编码的分析

本文详细地讨论了合成孔径雷达原始数据量化编码的原理以及对压缩算法进行了分析,并对块自适应量化编码原理进行了讨论。     

基于自适应重迭正交变换的音频信号编码

本文提出了一种基于自适应重迭正交变换的音频信号编码算法,讨论了变换系数的量化及自适应比特分配问题。实验结果表明该方法的编码质量优于传统的离散余弦变换,没有分块效应,而计算量则相当。     

使用变换域编码技术压缩SAR原始数据

首先分析了在合成孔径雷达（SAR）原始数据中通常使用的块自适应量化（BAQ）算法，然后在此基础上详细讨论了两种基于块自适应量化的变换域编码算法，即基于快速傅里叶变换块自适应量化（FFT-BAQ）和基于小波变换块自适应量化（WT-BAQ），并对这两种算法压缩得到数据解压缩获得图像与块自适应量化得到的图像进行分析比较，结果显示变换域编码技术能改善SAR原始数据压缩性能。     

采用高速DSP实现BAQ算法的应用研究

本文较为详细地介绍了最佳量化的基本方法以及块自适应量化编码的原理，同时给出了采用高速DSP芯片技术实现SAR原始数据压缩的原理和实现结果。     

用于卫星链路的自适应级联码研究

在Ka频段卫星通信系统中，自适应纠错编码是一种很好的抗衰减措施。本文首先分析了抗衰减措施对自适应纠错编码的要求，提出了用RS码作外码、基于1／2卷积码的可变码率收缩码作内码加交织器构造自适应级联码，并对其原理和性能进行了详细分析。仿真表明该自适应级联码编码增益变化范围可达3～12dB以上，适用于卫星下行链路的自适应纠错编码抗衰减对策。     

自适应调制与编码系统及其在WCDMA中的应用

本文主要讨论自适应调制与编码系统(Adaptive Modulation and Coding system）的原理，介绍AMCS实现的几个关键技术，包括RCPT（速率适配凿孔turbo）码、高阶调制、H-ARQ和MIMO（多输入多输出）系统。介绍了在WCDMA的高速下行分组接入业务（HSDPA）中使用的自适应调制编码机制，并讨论了可能增加的设备复杂度。     

语音的波形编码及其实时执行

数字语音编码主要解决如何压缩输出信息的比特率,以提高线路复用率。本文在简述了有关这一领域的概况之后,着重阐述了三种语音波形编码的主要原理及其实时执行方式,即自适应差分脉码调制(ADPCM);子频带编码(SBC)及自适应变换编码(ATC)。前两种结构较简单,可用单片数字信号处理机(DSP)获得实时实现;后一种结构复杂,且进行分块处理,故实时执行时需采用数组处理机。三种方式分别将比特率压缩至32、16及9.6Kbit/s的范围内。文中对所涉及的硬件结构亦作了一定的介绍。     

基于小波变换的嵌入式编码在图像压缩中的应用

由于图像数据量的巨大会使图像在存储和传输中受到制约,因此,图像压缩成为必然。图像压缩的关键技术包括对图像数据的变换、对变换数据的量化以及对量化后数据的熵编码。其中压缩中编码占有非常重要的位置。本文主要分析其中一种很流行的编码形式一嵌入式编码,分别比较分析了三种嵌入式编码的优缺点以及嵌入式编码的发展前景。     

AMR语音编码算法研究及复杂度剖析

作为 3GPPWCDMA的语音编码 (SpeechCoding)候选方案 ,自适应多速率 (AMR)语音编码是一种多模式集成的ACELP类语音编码方案。本文根据该编码方案的标准 ,分析了其方案实现中的关键算法 :高性能码本设计、高效码本搜索算法、多级矢量量化技术、预处理算法的简化等。最后 ,设计了定点ANSI -C程序对AMR语音编码算法各部分的复杂度进行了测算     

高清晰度电视信号用外插内插预测编码方法

本文介绍了一种高清晰度电视(HDTV)信号的数字传输用高效编码方法。由于HDTV信号的带宽宽,所以存在两个主要问题:一是HDTV信号的随机噪声比传统电视信号的大,因而导致编码的效率下降;二是需要很高的取样频率。这样,就限制了编码算法的硬件实现。因此,本文提出两种技术来解决这些问题:第一是时空自适应滤波器,用它可降低随机噪声并改善编码效率;第二是具有自适应内场/帧间预测的外插和内插编码算法,这种算法消除了因高的取样频率引起的问题并保证了高效编码性能。     

潜性与显性修辞原则：诚信与得体

修辞的原则是修辞界讨论较多的内容，但把修辞的原则分解为潜性原则和显性原则采讨论，尚不多见。修辞应该有潜性原则和显性原则之分。修辞的潜性原则是诚信，它是内在的，看不见，摸不着的；修辞的显性原则是得体，它是外在的，听得见，感受得到的。诚信是表达的出发点和落脚点。得体是诚信的结果和表现形式。诚信必须通过得体这个美丽的外衣来显现。但诚信和得体之问是非对称关系，因此，不可逆向推断。     

最小平方误差受限的FIR滤波器设计

在设计FIR滤波器时,往往会指定过渡带大小,但过渡带的引入只是为了便于滤波器的设计,而并不是物理上的需要,所以在设计中仅需指定截至频率。这是第一个设计理念。此外,在FIR滤波器的设计中存在两种准则:一是等波纹设计准则 (即最大误差最小化或者Chebyshev准则 ),另一种是平方误差最小准则。但在现实中两种准则往往要同时兼顾,所以仅基于其中一种准则来设计不能得到最佳结果。这是第二个设计理念。基于上述两种设计理念,提出了一种新的FIR滤波器设计算法。该算法采用最陡梯度下降法来对平方误差最小化下的最佳滤波器系数进行迭代修正,得到最佳结果。     

货币需求、储蓄存款与股市投机性

现有的有关股票市场发展对货币需求影响的研究,暗含着一个假设：货币流通速度不变。在一个投机性极强的股市里,这一假设难以成立。对Friedman的替代效应修正后,股市发展对货币需求影响与我国实际情况相吻合。股市发展对M1有正向作用,对M2有负向作用,后者的主要成因是我国股市具有极强投机性。     

CONTINUOUS-TIME MEAN-VARIANCE PORTFOLIO SELECTION WITH BANKRUPTCY PROHIBITION

A continuous-time mean-variance portfolio selection problem is studied where all the market coefficients are random and the wealth process under any admissible trading strategy is not allowed to be below zero at any time. The trading strategy under consideration is defined in terms of the dollar amounts, rather than the proportions of wealth, allocated in individual stocks. The problem is completely solved using a decomposition approach. Specifically, a (constrained) variance minimizing problem is formulated and its feasibility is characterized. Then, after a system of equations for two Lagrange multipliers is solved, variance minimizing portfolios are derived as the replicating portfolios of some contingent claims, and the variance minimizing frontier is obtained. Finally, the efficient frontier is identified as an appropriate portion of the variance minimizing frontier after the monotonicity of the minimum variance on the expected terminal wealth over this portion is proved and all the efficient portfolios are found. In the special case where the market coefficients are deterministic, efficient portfolios are explicitly expressed as feedback of the current wealth, and the efficient frontier is represented by parameterized equations. Our results indicate that the efficient policy for a mean-variance investor is simply to purchase a European put option that is chosen, according to his or her risk preferences, from a particular class of options.     

Dissolving the Moral Dilemma of Whistleblowing

The ethical debate on whistleblowing concerns centrally the conflict between the right to political free speech and the duty of loyalty to the organization where one works. This is the moral dilemma of whistleblowing. Political free speech is justified because it is a central part of liberal democracy, whereas loyalty can be motivated as a way of showing consideration for one’s associates. The political philosophy of John Rawls is applied to this dilemma, and it is shown that the requirement of loyalty, in the sense that is needed to create the moral dilemma of whistleblowing, is inconsistent with that theory. In this sense, there is no moral dilemma of whistleblowing. This position has been labelled extreme in that it says that whistleblowing is always morally permitted. In a discussion and rejection of Richard De George’s criteria on permissible whistleblowing, it is pointed out that the mere rejection of loyalty will not lead to an extreme position; harms can still be taken into account. Furthermore, it is argued that the best way is, in this as in most other political circumstances, to weigh harms is provided by the free speech argument from democracy. Lars Lindblom is a Ph D. student in philosophy at the Royal Institute of Technology, Stockholm, Sweden. He has worked as a business ethics consultant and has written on efficency, workplace inspections and business ethics.     

民商法视野中的合作社

从民商法视角看,作为市场经济的参与者,合作社是人们自愿联合的组织,是平等的自然人、法人等主体之间的联合;合作社的内部制度设计以法人治理结构为基准,但与一般公司法人治理结构并不完全相同;合作社的经营活动具有两重性,合作社与社员之间的交易具有非营利性,而与其他非社员利益主体之间的交易则具有营利性,因此在对外交易活动中必然要受价值规律和市场竞争规律的约束。     

我国现代粮食专业物流发展概况与趋势分析

现代粮食专业物流作为一种新兴产业,被喻为＂第三利润源泉＂,在经济发展中的地位和作用也越来越明显,有着旺盛的生命力和广阔的发展前景。我国粮食专业物流比其他物流发展相对滞缓,但由于粮食是一种大宗的特殊商品,以其数量大、牵涉面广、流通费用高,在整个物流中始终占据着重要的位置。分析了我国粮食专业物流概况、特点、现状及制约因素,探索性地提出了实现我国粮食专业物流科学化运作的对策建议。     

预应力混凝土管桩在不良地质条件下的设计与施工

预应力混凝土管桩作为一种成熟的桩基础形式已越来越被大家所接受,其以施工速度快、长度易调整、质量较可靠、造价较合理、易于检测、现场清洁等优点,被广泛地应用于工业与民用建筑中。本文结合实际工程,探讨预应力混凝土管桩在不良地质条件下的设计与施工。     

Mistaking Statistics for Rigor in American Business School Research： Should China Follow,or Lead in a New Direction？

The heavy emphasis on statistical rigor that business schools in American universities place on research is questionable in general and, for business schools in China, is not necessarily a good strategy by which either to produce useful research or to distinguish themselves from business schools in the United States. The reasons for this pertain to, first, what statistical analysis is good for in science; second, what statistical analysis is not good for in science; third, what statistical analysis is and is not good for in business research; fourth, how a large sample size is not generalizable but a single case is; fifth, how action research, design research, and Herbert Simon＇s ＂sciences of the artificial＂ all demonstrate rigor without statistics; and finally, the historical context that explains the turn to statistics in American business schools but is irrelevant to China. The recommendation is for business schools in China not necessarily to reject statistical research, but rather, to also pursue other, equally scientific forms of research, including those recognized by Herbert Simon.     

网络抗干扰及其评估方法

网络级抗干扰是一个新问题,它与网络的拓扑结构紧密相关。本文研究了无线网中干扰相关性,计算了理想拓扑的干扰独立路径数目的数目。网络抗干扰性能的另外一个问题是评估方法,本文提出了基于平面几何的评估方法,其中包含了距离和方位两个参数。该评估方法计算简单,物理意义明确,能很好地反应无线网的拓扑抗干扰性能。