时变时滞NCS控制器的改进设计

建立时滞差分不等式,得到网络化控制系统(NCS)的指数稳定判据,基于该判据设计NCS状态反馈控制器。该设计以线性矩阵不等式(LMI)形式给出,不包含任何自由矩阵,通过Matlab中的LMI工具箱进行求解。数值仿真结果表明,该设计具有计算量小、求解方便、保守性弱的特点。     

Biological properties of carbon/carbon implant composites with unique manufacturing processes

The goal was to manufacture carbon/carbon (C/C) composites through a unique procedure with improved biocompatibility and reduced debris release. C/C composites were prepared by chemical vapor deposition, and their biological properties were analyzed. With regard to mechanical properties, compressive strength/modulus was 219.1 MPa/9.72 GPa, flexural strength/modulus was 121.63 MPa/21.9 GPa, and interlaminar sheer was 15.13 GPa. Biocompatibility testing revealed: (1) the extract liquid from the C/C composites had no effect on cell proliferation; (2) the extract had no impact on micronucleus frequency as compared with the control groups (P > 0.05); (3) in vivo, there was mild tissue inflammation after implantation within the first 2 weeks, but there was no significant difference compared with the control group (P > 0.05); (4) the implants were well integrated into the host tissue, and debris was limited. The tested samples have excellent biocompatibilities and reduced release of debris. The demonstrated changes in manufacturing procedures are promising.     

Low temperature fabrication of high strength porous calcium phosphate and the evaluation of the osteoconductivity

Porous NaO₂–MgO–CaO–P₂O₅ bioglass doped beta-tri-calcium phosphate (β-TCP) bioceramic possessing high mechanical properties and well pore structure with high porosity and high pore connectivity has been prepared through dipping method with the porous polyurethane as the pore forming template. The sintering mechanism and the mechanical properties of the bioglass doped β-TCP scaffold have been investigated by the X-ray diffraction (XRD) analysis, Scanning electron microscope (SEM) and thermal differential analysis (DTA). The scaffold’s in vivo osteoconductivity has been evaluated by implantation of scaffolds into the femurs of New Zealand rabbits. The results show that the porous structure can achieve the densification process at a low temperature about 950°C by a solid solution sintering mechanism and hence dense macropore scaffold with a compressive strength of 4.32 MPa when the porosity is 75% has been obtained. The in vivo test shows that the Na₂O–MgO–CaO–P₂O₅ bioglass doped porous β-TCP bioceramic has a relatively fast bone formation after implantation; after 1 month implantation new deposited bone tissue has been detected on the strut of the porous scaffold and degraded particles also has been found on the surface of the new formed bone. After 6 months implantation the porous scaffold has been thoroughly covered with new formed bone. Results show that the Na₂O–MgO–CaO–P₂O₅ bioglass doped porous β-TCP bioceramic is potential bone tissue engineering scaffold for orthopedic use.     

Microwave-assisted hydrothermal synthesis of coralloid nanostructured nickel hydroxide hydrate and thermal conversion to nickel oxide

Coralloid nanostructured nickel hydroxide hydrate has been successfully synthesized by a simple microwave-assisted hydrothermal process using nickel sulfate hexahydrate as precursor and urea as hydrolysis-controlling agent. A pure coralloid nanostructured nickel oxide can be obtained from the nickel hydroxide hydrate after calcination at 400 °C. The thermal property, structure and morphology of samples were characterized by thermogravimetry (TG), temperature-programmed reduction (TPR), X-ray (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM).     

基于灰色预测理论的软件缺陷预测模型研究

软件缺陷是软件产品预期属性的偏离现象.妥善处理软件中的缺陷关系软件质量以及软件组织的生存与发展.利用开发过程中收集的软件缺陷的相关数据,依据灰色预测理论的核心:GM(1,1)来建立预测模型,对后续软件开发中缺陷的存在情况作出相应预测.实验表明该预测结果能指导软件组织较好地把握软件质量、合理分配测试资源,并在一定程度上帮助软件组织度量软件过程.     

圆锥裁剪BLOB的视频目标检测方法

真实场景的视频目标检测需要消除阴影、反射和鬼影等噪声的影响,以检测出运动目标和静止目标.为了实现系统性的视频目标检测,提出一种自适应圆锥裁剪联通块(TC-BLOB)榆测方法.基于BLOB知识,将3D颜色空间变换为夹角-模差2D空间后,定义一套圆锥裁剪规则划分出阴影BLOB和反射BLOB;再以一种持久化记忆PM方法判别出鬼影BLOB;最后改进双背景模型检测出静止目标和运动目标.采用不同环境视频进行实验的结果表明,文中方法足有效的,并有独立于后续跟踪的优点.     

基于DSP平台的激光二极管控制系统

介绍了以DSP芯片TMS320F2812为核心设计的控制平台、利用半导体制冷器和光功率传感器调节激光二极管工作温度和发射功率的控制系统;设计了具有良好性能的模拟通道,提出了针对特定调节对象的PID算法.结合优化设计的执行单元实现了很好的控制效果,有效地提高了激光二极管系统的稳定性和可靠性;设计的控制系统在环境温度-10℃～50℃时能够达到±0.03℃的控制精度.     

Effect of experimental methodology on the JND of the black level for natural images

Abstract— The effect of experimental methodology on the Just Noticeable Difference (JND) of the black level (BL) is assessed using a set of representative natural images. Two methodologies, known in psychophysics to determine JNDs, are mutually compared: an adapted method of adjustment with a same‐difference task and a one‐up‐two‐down staircase method with a two‐alternative forced‐choice task. Thus far, the literature has shown contradictory results for which of the two methods yields the lower difference thresholds. Experimental results show that the second method yields lower JNDs, but is slightly less efficient. Based on this second method, it was found that the JND of the BL for natural images ranges from 0.2 to 1.0 cd/m², varying with image content significantly.     

面向态势评估的一种有效的证据理论合成公式

战场态势评估是指挥决策的基础,如何进行合理的态势评估是C4ISR数据融合系统中的一个重要环节.针对态势评估中的证据在合成过程中的重要程度不同,通过引入证据权重值,提出了一种新的D-S证据理论合成方法.实验表明该方法可提高态势评估中证据合成的合理性与可靠性,能得到更理想的合成结果,更符合实际情形.