Design and Architecture of Low‐Latency High‐Speed Turbo Decoders

In this paper, we propose and present implementation results of a high‐speed turbo decoding algorithm. The latency caused by (de)interleaving and iterative decoding in a conventional maximum a posteriori turbo decoder can be dramatically reduced with the proposed design. The source of the latency reduction is from the combination of the radix‐4, center to top, parallel decoding, and early‐stop algorithms. This reduced latency enables the use of the turbo decoder as a forward error correction scheme in real‐time wireless communication services. The proposed scheme results in a slight degradation in bit error rate performance for large block sizes because the effective interleaver size in a radix‐4 implementation is reduced to half, relative to the conventional method. To prove the latency reduction, we implemented the proposed scheme on a field‐programmable gate array and compared its decoding speed with that of a conventional decoder. The results show an improvement of at least five fold for a single iteration of turbo decoding.     

基于可信度的Bayes融合方法在可靠性评估中的应用

在工程实践中,验前信息往往具有多源性的特点.如何把各类先验信息融合成为现场试验的验前信息就成为一个不可回避的问题.本文针对指数寿命型产品,在考虑其失效率的验前信息可信度时,给出其失效率的Bayes估计方法.通过具体实例说明考虑验前信息可信度时Bayes估计有明显改善.     

Transition Metal Oxide Work Functions: The Influence of Cation Oxidation State and Oxygen Vacancies

Transition metal oxides are capable of a wide range of work functions. This quality allows them to be used in many applications that involve charge transfer with adsorbed molecules, for example as heterogeneous catalysts, as charge‐injection layers in organic electronics, and as electrodes in fuel cells. Chemical and structural factors can alter transition‐metal oxide work functions, often making their work functions difficult to control. Little is known about the effects of the cation oxidation state and point defects on the oxide work function. It is necessary to understand how such chemical and structural factors affect work functions in order to controllably tune transition metal oxides for desired applications. Here, a correlation between the oxide work function and cation oxidation state is demonstrated. This correlation is attributed to the change in cation electronegativity with oxidation state. A model is presented that relates the work function to the oxygen deficiency for d⁰ oxides in the limit of dilute oxygen vacancies. It is proposed that the rapid initial decrease in work function, observed for d⁰ oxides, is caused by an increase in the density of donor‐like defect states. It is also shown that oxides tend to have decreased work functions near a metal/metal‐oxide interface as a consequence of the relationship between defects and work function. These insights provide guidelines for tuning transition metal oxide work functions.     

CCD相机调制传递函数的测试分析

调制传递函数(MTF)是评价CCD相机成像系统质量的重要参数,它能真实地反映相机拍摄时的空间频率与图像对比度的关系。CCD相机的MTF测试中最关键的是靶标的选择,它决定了整个系统的测量精度和操作过程的复杂程度。理想的靶标函数是正弦函数,但制作光出射度随正弦波规律变化的分辨率板是非常困难的,因此利用明暗相间、相互平行的黑白条纹分辨率板来代替正弦波分辨率板,提出了测量MTF的方法。重点对CCD相机在奈奎斯特频率处的MTF测试结果进行了分析与评价。     

统一的BPSK信号功率谱分析

二进制移相键控BPSK调制是载波相位按基带脉冲而键控改变的一种数字调制方式,其功率谱推导在传统上也是按照将基带脉冲的频谱左右频移进行的,因而要求频移后的谱没有混叠,即只有高载频才能忽略近似性,具有一定的局限。本文按照直接载波调制的思路,推导出BPSK已调信号功率谱的准确表达式,既消除了高载频的限制,也统一了对于BPSK功率谱的基带分析和载波分析方法。仿真结果表明了新表达式的正确性。     

柠檬醛对阿糖胞苷抗白血病细胞HL-60强效增敏作用研究

通过对柠檬醛与临床首选药物之一阿糖胞苷联用抗白血病细胞株HL-60的研究,探索二者联用的生物效应及其作用机制。采用MTT和DAPI核染色等方法观察柠檬醛同阿糖胞苷的不等浓度组合HL-60的增殖抑制和诱导凋亡作用,相分析电泳激光散射技术检测联用对细胞表面电荷的影响。柠檬醛显示一定的抑制HL-60增殖,促进其凋亡的效应,并与阿糖胞苷有较显著的协同性,增加柠檬醛浓度与药物阿糖胞苷联合作用可使膜表面电位下降的幅度增大。柠檬醛有联合阿糖胞苷临床治疗潜力。     

Background memory area estimation for multidimensional signalprocessing systems

Memory cost is responsible for a large amount of the chip and/or board area of customized video and image processing system realizations. In this paper, we present a novel technique-founded on data-flow analysis which allows one to address the problem of background memory size evaluation for a given nonprocedural algorithm specification, operating on multidimensional signals with affine indexes. Most of the target applications are characterized by a huge number of signals, so a new polyhedral data-flow model operating on groups of scalar signals is proposed. These groups are obtained by a novel analytical partitioning technique, allowing to select a desired granularity, depending on the application complexity. The method incorporates a way to tradeoff memory size with computational and controller complexity     

头部和尾舵布局对弹箭俯仰气动特性影响

采用数值模拟的方法并经过风洞实验验证分析了超音速下无翼式布局火箭弹模型俯仰气动特性随头部形状和尾舵面积的变化规律,得出在头部长细比固定不变的条件下选用单锥型弹头较双锥形弹头有更好的稳定性;选用面积大的尾舵具有更好的法向过载和稳定性;为无翼式布局弹箭气动设计提供了依据.     

基于LabVIEW的压力采集虚拟仪器系统

将虚拟仪器技术引入了火炮内弹道测试领域，开发了以PC机为硬件平台、以美国National Instrument公司的虚拟仪器开发工具LabVIEW为软件平台的虚拟仪器系统。压力采集虚拟仪器系统在计算机上通过软件控制完成采集参数设置、数据采集、分析处理、存储和打印等功能，满足了实际动态测试分析的需要。并自行编写了数据采集卡的调用程序，实现了即插即用功能。     

WCDMA网络用户感知与无线环境关联分析研究

当前网络优化工作越来越从KPI指标优化向用户感知优化转变,但是在日常的优化工作中,如何将用户感知与常规的无线环境优化相关联,并通过优化无线环境实现用户感知的提升,仍然是困扰优化人员的难题。对海量实测数据进行覆盖、干扰与数据速率的关联分析,特别关注覆盖、干扰与影响用户体验的下限速率的关系,得到无线环境与数据速率这一重要的内在关联关系,从而确定保证不同业务速率要求的无线环境需求,为网络规划和优化工作提供参考。