Hybrid Temporal Error Concealment Methods for Block-Based Compressed Video Transmission

Boundary matching algorithm (BMA) and decoder motion vector estimation (DMVE) are two well-known temporal error concealment methods using the matching-based approach. In these two methods, the motion vector of each missing block is estimated by choosing one among candidate motion vectors which minimizes a sum of absolute differences (SAD) between boundary pixels of the corrupted macroblock. In general, the performance of DMVE is better than that of BMA. However, depending on the location or pattern of the corrupted block, BMA produces higher visual quality than DMVE. In this paper, we propose two types of hybrid error concealment methods; switching method and blending method. The switching method chooses one of two results obtained by BMA and DMVE based on the normalized SAD values. In the blending method, the weighted sum of the results concealed by the aforementioned two methods is utilized to improve the performance of error concealment. In order to reduce blocking artifacts further, the modified overlapped-block motion compensation is adaptively applied to the concealed blocks. Simulation results show that the proposed methods outperform other techniques in terms of subjective visual quality as well as PSNR performance.     

一种负载均衡的移动Ad-hoc网络路由协议及改进

随着移动ad hoc网络负载的增加，现有路由协议的性能将急剧下降。为适应重负载网络，本文提出了一种带宽估算模型和负载平衡技术，并结合AODV（Ad hoc On-demand Distance Vector Routing）设计了新的路由协议。同时考虑到时廷因素，对新协议进一步改进。仿真表明，本文提出的协议可以提高分组传送率，降低平均端到端时延，并减少路由开销。     

A New Approach for Manufacturing a High Porosity Ti-6Al-4V Scaffolds for Biomedical Applications

Titanium and its alloys are currently considered as one of the most important metallic materials used in the biomedical applications, due to their excellent mechanical properties and superior biocompatibility. In the present study, a new effective method for fabricating high porosity titanium alloy scaffolds was developed. Porous Ti-6Al-4V scaffolds are successfully fabricated with porosities ranging from 30% to 70% using spaceholder and powder sintering technique. Based on its acceptable properties, spherical carbamide particles with different diameters （0.56, 0.8, and 1mm） were used as the space-holder material in the present investigation. The Ti-6Al-4V scaffolds porosity is characterized by using scanning electron microscopy. The results show that the scaffolds spherical-shaped pores are depending on the shape, size and distribution of the space-holder particles. This investigation shows that the present new manufacturing technique is promising to fabricate a controlled high porosity and high purity Ti-6Al-4V scaffolds for hard tissue replacement.     

Effect of Si3N4 Addition on the Mechanical Properties, Microstructures, and Wear Resistance of Ti-6Al-4V Alloy

In order to improve the wear resistance of Ti-6Al-4V, different amounts of Si3N4 powder were added into the alloy powder and sintered at 1250℃. Porous titanium alloy with higher wear resistance was successfully fabricated. At sintering temperature, reaction took place and a new hard phase of Ti5Si3 formed. The mechanical properties of the fabricated alloys with different amounts of Si3N4 addition were investigated. The hardness of Ti-6Al-4V, which is the index of wear resistance, was increased by the addition of Si3N4. Amounts of Si3N4 addition have very significant influences on hardness and compressive strength. In present study,titanium alloy with 5 wt pct Si3N4 addition has 62% microhardness and 45% overall bulk hardness increase,respectively. In contrast, it has a 16.4% strength reduction. Wear resistance was evaluated by the weight loss during wear test. A new phase of Ti5Si3 was detected by electron probe microanalyzer （EPMA） and X-ray diffraction （XRD） method. The original Si3N4 decomposed during sintering and transformed into titanium silicide. Porous structure was achieved due to the sintering reaction.     

色度域亮度域信息融合的监控视频重压缩取证

为解决当前视频重压缩取证方法没有考虑色度域信息、取证准确度低的问题,提出一种面向最新多用途视频编码(versatile video coding, VVC)标准色度域亮度域信息融合的监控视频重压缩取证方法(CLF-SVRF)。基于VVC标准的编码原理,从监控视频的色度域和亮度域维度分析并确定VVC视频码流中与压缩次数密切相关的基础码流特征;基础码流特征包括色度域和亮度域编码单元(coding unit, CU)的划分类型及预测模式;结合拉格朗日率失真优化技术分析随着压缩次数的增加,色度域亮度域CU划分类型和预测模式的变化;进一步确定色度域亮度域CU划分类型和预测模式可以作为检测视频压缩次数的基础码流特征;接着考虑视频监控应用对重压缩取证方法低复杂度的需求,基于色度域亮度域CU划分类型和预测模式构建低复杂度高级码流特征;将高级码流特征输入支持向量机完成监控视频的重压缩取证。实验结果表明,与当前先进方法相比,CLF-SVRF方法的监控视频重压缩取证准确度平均提升了13.53%,同时可以大幅度地降低重压缩取证耗时,重压缩取证时间平均减少了47.42%。     

血清样品中胆固醇的携带式测定仪的开发

利用色谱原理开发荧光芯片,并测定了血清中的总胆固醇含量。分析系统由荧光色谱芯片和荧光阅读器组成,荧光色谱芯片包括塑料盒和纸条,显色剂(AEC),胆固醇氧化酶(CO),胆固醇酯酶(CE),过氧化氢酶(HRP)混合溶液喷在纸条上。在1—4mg/mL浓度范围内,胆固醇标准溶液和荧光强度的变化有线性关系(r=0．979),其回收率为106．5％-94％。该法测定的结果和Hitachi 747全自动生化分析仪有良好的相关性(r=0．895)。本研究所开发的总胆固醇测定方法有操作简单,快速(8min),取样量少(5μL)的特点,适合于携带式测定仪的开发。     

ELASTOHYDRODYNAMIC LUBRICATION ANALYSIS OF LAYERED LINE CONTACT BY THE BOUNDARY ELEMENT METHOD

This paper presents a numerical routine to compute the contact characteristics of elastomer layered cylinders lubricated by isoviscous liquids. The indentation of the elastic layer is calculated from boundary integral equations which are solved by linear and quadratic boundary element methods for a finite plane model and a circular representation of the junction. The hydrodynamic equation is also transformed into a boundary integral equation and solved by Simpson's rule. Some factors which possibly affect numerical accuracy are examined. Examples for finite plane and circular layer are analysed with reference to parameters for printing press roller contact, in which results are obtained for the indentation, film thickness and liquid pressure, as well as internal stresses through the simultaneous solution of the elasticity and hydrodynamic equations. The results show that high precision is easily achieved and the method is efficient for such layered problems.     

基于高频电阻抗信号的结构损伤监测

给出了利用高频电阻抗信号进行结构损伤识别的精确定量分析方法.考察压电片－黏结层－主体结构组成的一个耦合结构系统，主体结构采用一维模型并只考虑轴向振动，引入剪滞模型来描述压电片与主体结构之间的剪力传递，考虑压电片的动力效应，采用传递矩阵法导出了这一耦合结构的系统方程，得到了压电片电导纳的解析表达式.通过算例验证了所给出方法的正确性和有效性.计算结果表明，弱界面对电阻抗信号有较大的影响，利用电导纳的虚部可以清楚地检测到界面的弱黏结；采用电阻抗技术能够很好地识别结构局部的细小损伤.     

Driving characteristics of octagon-type ultrasonic motor

Structure of the octagon-type ultrasonic motor was proposed and designed so as to allow the motor to drive small actuator. The stator of the motor consisted of the octagon shape elastic body and four rectangular plate ceramics. The four ceramics were attached to outer surfaces of the octagon elastic body. The same phase voltages were applied to the ceramics on horizontal surfaces, and 90° phase difference voltages were applied to the ceramics on vertical surfaces. When the AC voltage with 90° phase difference was applied in ceramics, the elliptical displacement of unimorph bars was generated by generating bending vibration. To find the maximum displacement model that generates elliptical displacement at the centers of the inner surfaces, the finite element analysis program ATILA was used. The analyzed results were compared to the experimental results. As a result, the speed and torque are increased linearly by increasing the input voltage and the speed of motors can be controlled by changing the applied voltages.     

Improvement of Dielectric and Interface Properties of CeO2 Buffer Layer by Using the Metal Seed Layer and N2 Plasma Treatment

In this paper, we investigated the feasibility of cerium oxide (CeO₂) films as buffers layer of MFIS (metal ferroelectric insulator semiconductor) type capacitors. CeO₂ layer were prepared by a two-step process of a low temperature film growth and subsequent RTA (rapid thermal annealing) treatment. By applying a cerium (Ce) metal seed layer of 4 nm, unwanted SiO₂ layer generation was successfully suppressed at the interface between the buffer layer and the Si substrate. After N₂ plasma treatment, the leakage current was reduced by about 2-orders. By employing a N₂ plasma treatment, we were able to successfully obtain good properties at the interface between the buffer layer and the Si substrate.