迫零对Turbo码的性能影响

从距离谱的角度对迫零在Turbo码中的作用进行了理论分析。通过仿真，研究了迫零对Turbo码性能的影响。仿真结果表明，Turbo码编码器迫零处理有助于改善Turbo码的性能。     

A time aggregation approach to Markov decision processes

We propose a time aggregation approach for the solution of infinite horizon average cost Markov decision processes via policy iteration. In this approach, policy update is only carried out when the process visits a subset of the state space. As in state aggregation, this approach leads to a reduced state space, which may lead to a substantial reduction in computational and storage requirements, especially for problems with certain structural properties. However, in contrast to state aggregation, which generally results in an approximate model due to the loss of Markov property, time aggregation suffers no loss of accuracy, because the Markov property is preserved. Single sample path-based estimation algorithms are developed that allow the time aggregation approach to be implemented on-line for practical systems. Some numerical and simulation examples are presented to illustrate the ideas and potential computational savings.     

广义物质平衡计算在凝析气藏开采动态预测中的应用

从经济的角度考虑 ,对小型凝析气藏衰竭式开采动态的预测往往不必或不值得进行数值模拟研究。常规物质平衡 (黑油 )计算方法只局限于黑油和干气藏 ,应用于凝析气藏则存在很大的误差。Walsh提出的广义物质平衡计算方法 ,可用于包括黑油、干气藏、挥发油气藏和凝析气藏在内的所有油气藏。文中将一个小型凝析气藏衰竭式开采动态的数值模拟结果与广义物质平衡计算结果进行了对比 ,结果表明 ,Walsh方法简便、应用更广泛 ,可用于规模较小、不适合进行数值模拟研究的凝析气藏的现场开发优化。     

A transmit/receive IF chip set for WCDMA mobiles in 0.35 /spl mu/m CMOS

An implementation of the IF section of WCDMA mobile transceivers with a set of two chips fabricated in an inexpensive 0.35-/spl mu/m two-poly three-metal CMOS process is presented. The transmit/receive chip set integrates quadrature modulators and demodulators, wide dynamic range automatic gain control (AGC) amplifiers, with linear-in-decibel gain control, and associated circuitry. This paper describes the problems encountered and the solutions envisaged to meet stringent specifications, with process and temperature variations, thus overcoming the limitations of CMOS devices, while operating at frequencies in the range of 100 MHz-1 GHz. Detailed measurement results corroborating successful application of the new techniques are reported. A receive AGC dynamic range of 73 dB with linearity error of less than /spl plusmn/2 dB and spread of less than 5 dB for a temperature range of -30/spl deg/C to +85/spl deg/C in the gain control characteristic has been measured. The modulator measurement shows a carrier suppression of 35 dB and sideband/third harmonic suppression of over 46 dB. The core die area of each chip is 1.5 mm/sup 2/.     

基于图像数据库的动态场景生成系统

实现各类目标和背景下动态场景的计算机编辑和生成，首先应对组成动态场景的要素进行分析，即目标，目标运动规律和特殊事件四个要素，然后通过编程由四个模块完成相应功能。目标，背景编辑模块可对目标，背景图像进行各种处理，并对重要特征量进行计算，运动路径模块可指定目标的运行规律，包括路线，大小和角度变化等。特殊事件模块可加入独立目标的各类典型事件，如运动的干扰物等。最后通过动态场景合成由计算机自动生成所需的动态场景图像。所需的原始目标，背景图像来源于图像数据库管理系统，通过索引项可便携地找到。     

CVD金刚石膜生长过程的Raman分析

采用激光Raman散射分析法对CVD金刚石膜的生长过程进行研究 ,讨论在金刚石膜生长的不同阶段 ,膜内金刚石和非金刚石成分的相对含量及其残余应力的变化情况     

基于HOP的可调光编码／解码器的研究

提出了一种基于全息光处理器的可调光编码/解码器的实现方案。全息光处理器可以在空间进行编/解码，每个通信网络单元可以采用任意速率的数字或模拟的调制信号，它非常适合于多媒体的通信网络环境，通过对全息光处理器的折射率大小和位置的控制，当一个输入光脉冲经过光处理器中具有特定折射率的空间位置后，便可在处理器的输出端口得到合适的输出信号。本文给出了这种基于全息光处理器的可调光编码/解码器的仿真实验，结果是可行的，与以前文献中提出的结构相比，减小了硬件实现的复杂性，降低了成本和功耗，便于集成。     

Algorithm for finding all k nearest neighbors

A very simple algorithm for computing all k nearest neighbors in 2-D is presented. The method does not rely on complicated forms of tessellation, it only requires simple data binning for fast range searching. Its applications range from scattered data interpolation to reverse engineering.     

Al-Cu-Fe系初生准晶相凝固过程的电子显微分析

采用包括金相（OM），粉末X射线衍射（XRD），扫描电子显微镜（SEM）观察和透射电子显微（TEM）分析等方法，研究了铸态Al592.Cu36.8Fe3.0Si1.0合金（700℃保温2．5h后水淬）的显微组织及相组成。发现铸锭中存在4种相：准晶I相，τ3相（或φ相），θ－Al2Cu相和η－AlCu相，凝固过程可描述为：初生晶是准晶Ⅰ相；在保温过程中发生包晶或共晶反应（L＋i→τ3(或φ）或L→τ3（或φ）＋i)形成的τ3相（或φ相），呈微畴结构；而剩余液体水淬形成θ－Al2Cu相和η－AlCu 相。