一种温度自适应无线传感网络时间同步方法

无线传感器网络节点中的廉价晶振极易受到温度、电压、湿度等工作环境因素的影响.节点晶振的这一特性,为室外大规模无线传感器网络时间同步技术带来了两方面的挑战:(1) 过高的通信开销;(2) 精度与能耗之间的不平衡.针对以上问题,提出了一种基于温度感知的、自适应的无线传感器网络时间同步算法.该算法能够依赖本地温度信息对节点时间频偏进行估计及补偿,在保证算法同步精度的同时,降低了网络通信开销.除此之外,提出一种动态同步周期调节机制,使得算法能够根据当前环境温度变化情况对节点同步周期进行动态调节,从而达到了能耗与精度之间的平衡.大量仿真实验结果表明:所提出的时间同步算法可将通信能耗降低至传统同步算法的10%;且在环境温度不断变化的情况下,80%的频偏估计值其误差小于0.5ppm.故,所提出的时间同步方法能够有效地适用于室外环境下部署的大规模无线传感器网络.     

NURBS双向蒙皮造型方法的研究与实现

本文通过对ＮＵＲＢＳ造型方法技术的研究，在自主开发的ＳｕｐｅｒＭａｎＣＡＤ／ＣＡＭ集成系统中成功地实现了基于复杂曲线的ＮＵＲＢＳ双向蒙皮曲面的造型功能，从而建立了完全基于ＮＵＲＢＳ方法的ＣＡＤ／ＣＡＭ系统．通过大量的工程应用和实例验证表明所研究的ＮＵＲＢＳ方法是一种适用于复杂外形产品设计与制造的、灵活有效的造型方法．     

滤除SEMG工频干扰的数字陷波器设计

50 Hz工频干扰是表面肌电信号（SEMG）的主要干扰源之一,消除工频干扰是表面肌电信号处理中的一项重要技术。鉴于原有模拟信号调理电路在工频消噪这一环节上的不足,设计了一种50 Hz数字陷波器用以消噪,减小干扰。实验证明,采用基于窗函数法的FIR原理设计的50 Hz数字陷波器能有效滤除SEMG中的工频干扰并基本不影响50 Hz周围有效SEMG的获取。     

基于广义元球的一般约束变形

在计算机动画和形状设计中，变形是一个非常重要的工具.基于广义元球所具有的特殊势函数分布，提出了一个新的包含点、线、面和体约束的一般变形模型.用户定义一系列约束、每个约束的影响半径和偏移量，变形模型根据每个约束和其影响半径产生该约束的广义元球.广义元球确定了一个以约束点集为中心的势函数，该势函数在约束点集处为1，在影响半径处渐变为0.模型直接对整个空间进行变形，而与物体的表示无关，并且变形可由偏移量和广义元球的参数来细微调整.实验表明，该一般约束变形模型不仅有效，而且使传统方法难以做到的线、面、体约束变形成     

Characteristics of heating process in microwave applicators with elements in periodic motion

Moving elements have been widely used in microwave applicators to improve heating uniformity. However, elements in periodic motion can lead to temperature oscillations in the process of heating. In this case, the processed samples are difficult to reach target temperature and the control system may also become unstable. Aiming at overcoming these problems, we investigate the temperature response of the heating process in microwave applicators with elements in periodical motion in this article. By modeling periodical motion as a periodical heat source, the temperature characteristics can be obtained by solving the heat transfer equation with eigenfunction expansions. The results show that the amplitude of temperature oscillations decreases with angular velocity of the element's motion, which is verified by experiments. It means that temperature oscillations can be reduced by increasing the element's velocity, which is helpful to improve the heating performance in microwave applicators.     

纳米CeO2的紫外吸收和表面改性研究

紫外吸收光谱分析氨水沉淀法制备的粒度在10nm的纳米二氧化铈表明在200～480nm的范围具有较好的紫外吸收能力。用无水乙醇为溶剂,硬脂酸为改性剂,初步探讨了纳米CeO2进行表面改性机理。活化度和吸油值分析表明,当硬脂酸用量在2．5％时,已经有较好改性效果,为纳米CeO2在聚合物中的应用提供一定的参考价值。     

Functionalised Anodised Aluminium Oxide as a Biocidal Agent

In this article, we describe the antimicrobial properties of a new composite based on anodic aluminium oxide (AAO) membranes containing propyl-copper-phosphonate units arranged at a predetermined density inside the AAO channels. The samples were prepared with four concentrations of copper ions and tested as antimicrobial drug on four different strains of Escherichia coli (K12, R2, R3 and R4). For comparison, the same strains were tested with three types of antibiotics using the minimal inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests. Moreover, DNA was isolated from the analysed bacteria which was additionally digested with formamidopyrimidine-DNA glycosylase (Fpg) protein from the group of repair glycosases. These enzymes are markers of modified oxidised bases in nucleic acids produced during oxidative stress in cells. Preliminary cellular studies, MIC and MBC tests and digestion with Fpg protein after modification of bacterial DNA suggest that these compounds may have greater potential as antibacterial agents than antibiotics such as ciprofloxacin, bleomycin and cloxacillin. The described composites are highly specific for the analysed model Escherichia coli strains and may be used in the future as new substitutes for commonly used antibiotics in clinical and nosocomial infections in the progressing pandemic era. The results show much stronger antibacterial properties of the functionalised membranes on the action of bacterial membranes in comparison to the antibiotics in the Fpg digestion experiment. This is most likely due to the strong induction of oxidative stress in the cell through the breakdown of the analysed bacterial DNA. We have also observed that the intermolecular distances between the functional units play an important role for the antimicrobial properties of the used material. Hence, we utilised the idea of the 2D solvent to tailor them.     

采用PLC实现温室变温控制的设计

本文介绍了采用PLC实现温室变温控制的方法,采用这种方法,PLC接口线路简单,外围元器件较少,整个系统运行可靠性高,保证了温室变温控制的质量。     

一种新型的简易测温系统电路

介绍一种新型的简易测温系统电路。测温系统采用一种新的电流／脉宽转换电路,与常用的测温系统比较,具有测量范围广、精度高、构成简单、成本低廉等优点。     

Temperature of the Limiter Surface Measured by IR Camera in HT-7 Tokamak

Temperature measurement by IR （infrared） camera was performed oll HT-T tokamak. particularly during long pulse discharges, during which the temperature of the hot spots on the belt limiter exceeded 1000℃. The heat load on the surface of the movable limiter could be obtained through ANSYS with the temperature measured by IR-camera. This work could be important for the temperature measurement and heat load study on the first wall of EAST device.