基于变移霍夫曼编码的SOC测试数据压缩

从理论上分析了V IHC编码[6]的不足后,提出了一种改进的SOC测试数据压缩编码方法——变移霍夫曼编码(HSC),并给出了相应解码器的设计。实验结果表明,HSC编码不仅具有与V IHC编码[6]相近的压缩比,而且其解码器的硬件开销仅为后者的1/2~1/3。     

学习策略实现的条件和加法器通路时延故障测试生成

时延故障对高速运算电路性能有着关键性的影响，本文对高速加法器之一的条件和加法器的通路时延故障作了研究。首先对其提出了一种可测性设计，主要特点是硬件成本低和测试向量少，且实现了完全的无险象强健时延故障可测性。在此基础上，进一步提出了一种学习策略的方法，实现了任意位数条件和加法器通路时延故障的测试生成，使得测试难度下降，测试时间缩短，测试效率提高。仿真实验结果表明了该方案的有效性。     

基于BTM的物联网服务发现方法

针对物联网（IoT）服务描述文本篇幅较短、特征稀疏,直接采用传统的主题模型对IoT服务建模得到的聚类效果不佳,从而导致无法发现最佳服务的问题,提出了一种基于BTM的IoT服务发现方法。该方法首先利用BTM挖掘现有IoT服务的隐含主题,并通过全局主题分布和主题-词分布计算推理得到服务文档-主题概率分布;其次利用K-means算法对服务进行聚类,并返回服务请求的最佳匹配结果。实验结果分析表明,该方法能够有效提高IoT服务的聚类效果,从而得到匹配的最佳服务。与现有的HDP（Hierarchical Dirichlet Process）、基于K-means的隐狄利克雷分配（LDA-K）等方法相比,该方法进行最佳服务发现的准确度（Precision）和归一化折损累积增益（NDCG）均有一定幅度的提高。     

Design of a wideband filtering power divider with good in‐band and out‐of‐band isolations

In this article, a wideband filtering power divider with good in‐band and out‐of‐band isolations is designed based on a hybrid Wilkinson and Gysel structure. To achieve a good in‐band response, two additional in‐band transmission poles can be introduced by installing the coupled‐line structures at each port. By mounting a stepped impedance open stub at the input port, two transmission zeros are generated near the passband to improve the passband skirt. Furthermore, the out‐of‐band rejection and isolation are achieved by the other two transmission zeros, which are produced by the open stub and the three coupled‐line sections mentioned above. Additionally, a good in‐band isolation is realized by the isolation resistor between output ports. For the demonstration, a wideband filtering power divider centered at 1.5 GHz with a 56% fractional bandwidth and 20‐dB isolation is designed and fabricated. The simulated and measured results are in good agreement with each other.     

MEMS加速度计混合误差标定补偿方案

针对微机电系统(MEMS)加速度计在实际使用过程中存在非正交零偏误差和温度漂移误差的问题,提出了一种混合误差标定补偿算法。算法通过分析加速度计温度与误差的关系,在不同温度区间下建立加速度计输出的误差模型,在每个温度区间采用十二位置校准法对加速度计的非正交零偏误差进行标定补偿,得到精确的零偏和刻度因子,同时采用最小二乘法拟合零偏和刻度因子与温度的一维关系函数,最终实现不同温度区间下的动态误差补偿。实验结果表明,本算法可使加速度计输出的精度提高1个数量级,补偿效果明显。     

基于加法生成器的低功耗测试

本文提出了一种基于算术加法生成器的测试或内建自测试的低功耗测试方法。该方法对原测试矢量进行伪格雷码编码,优化被测电路的开关活动率,从而实现低功耗测试。8位行波进位加法器和16位超前进位加法器的实验分析表明,编码后的测试矢量显著地降低了被测电路的开关活动率;基于FPGA的实验结果表明,对于8位行波进位加法器,该方法将电路的平均动态功耗降低了15．282%,对于16位超前进位加法器,则降低了12．21%。该测试方法能侦测到被测电路基本组成单元的任意组合失效;由于原电路中加法器的复用,该测试方法可将测试硬件开销降至最小,但不会降低测试性能。     

Thermal‐cycle dependent residual stress within the crack‐susceptible zone in thermal barrier coating system

Nondestructive and accurate measurement of residual stress in ceramic coatings is challenging, but it is crucial to the assessment of coatings failure and life. In this study, for the first time, the thermal‐cycle dependent residual stress in an atmosphere plasma sprayed thermal barrier coating system has been nondestructively and accurately measured using photoluminescence piezo‐spectroscopy. Each thermal cycle consists of a 5‐minute heating held at 1150°C and a 3‐minute water quenching. The measurement was performed within a crack‐susceptible zone in the yttria‐stabilized‐zirconia (YSZ) top coat (TC) closely above the thermally grown oxide layer. A YSZ:Eu³⁺ sublayer was embedded in TC as a stress sensor. It was found that the initial residual stress was compressive, with a mean value of 240 MPa, which rapidly increased to 395 MPa after 5 thermal cycles (12.5% life) and then increased gradually to the peak of 473 MPa after 25 thermal cycles (62.5% life). After 30 thermal cycles (75% life), the mean stress dropped abruptly to 310 MPa and became highly heterogeneous, with gradual reduction toward final spallation. The heterogeneous stress distribution indicates that many microcracks nucleated at different locations and the spallation occurred due to the coalescence of the microcracks.     

Weighting ensemble least-square method for flutter derivatives of bridge decks

In this paper, a reliable but simple identification method, here called the weighting ensemble least-square method (WELS), has been developed to extract all eight flutter derivatives of bridge deck from free vibration records. For every wind speed, free vibration test of section model is generally repeated several times in order to obtain more reliable parameter estimates. In the WELS method, many free vibration records at the same wind speed are regarded as an ensemble. The common mode parameters are then identified simultaneously from the ensemble data. The parameter fit is obtained by a nonlinear least-square method. Weighting factors are proposed to make each experiment record with the same weight in total residual error analysis. The ensemble composed of many records can reduce the effect of the colored noise of few records on the convergence of least-square iteration process. The flutter derivatives of two section models are identified to indicate the reliability and effectiveness of the WELS method.     

浅谈市政工程施工测量放线程序化

将道路工程平面上直线段 ,圆曲线段 ,缓和曲线段内任意一点的坐标和高程 ,同附近控制点 (测站点 )的坐标和高程编制成计算机操作程序 ,实现施工区域内任意一点测量放线程序化     

自适应卡尔曼滤波在磁干扰姿态测量中的应用

针对姿态测量系统陀螺仪漂移、周围局部磁场干扰制约姿态测量精度的问题,提出一种基于四元数的自适应卡尔曼滤波(q-AKF)的方法。该方法利用陀螺输出建立姿态解算误差角的状态方程,以磁强计输出构造自适应测量噪声协方差矩阵。仿真结果表明,相比无损卡尔曼滤波(UKF)算法和扩展卡尔曼滤波(EKF)算法,采用q-AKF算法补偿得到的姿态角误差不大于0.5°。q-AKF算法对磁强计进行补偿,能够有效抑制陀螺的漂移误差,提高磁干扰环境下姿态解算精度,具有较高的工程应用价值。