Dynamic response of diamond sensors to ionizing radiation beams

Prototypes of radiation detectors for clinical dosimetry were constructed using commercially available synthetic diamond. Polished diamond plates of detector grade and standard quality were used. The metallization scheme was a typical Ag–Ag contact for the detector grade diamond and a new metallization technique for the standard quality diamond. This was for determining which detector is more appropriate for radiotherapy dosimetry needs. The detector signal was analyzed as a function of bias voltage in the 0–500 V range both in absence of radiation and in a Co-60 gamma-ray beam. The response linearity was assessed in Co-60 gamma-ray beam for dose-rates in the range from 0.2 to 1.2 Gy min⁻¹. Pre-irradiation effects were also investigated. Signal rise time, signal stability and reproducibility are reported and discussed.     

Ab initio calculation of adhesion and potential corrugation of diamond (001) interfaces

The system consisting of two diamond (001) surfaces in contact was studied by means of plane-wave/pseudopotential density functional calculations. Different hydrogen coverages, ranging from fully hydrogenation to bare surfaces, were considered. The adhesion energy was calculated as a function of both the separation and the lateral displacement of the two surfaces. The effects of dangling carbon bonds on the adhesion and potential corrugation are quantitatively discussed.     

串口通信在CVD金刚石膜生长系统中的应用

本文主要介绍在CVD金刚石膜生长系统中如何利用MSComm控件实现串口通信，并给出了以Delphi开发的实例程序。此外阐述了以分时循环方式实现单通道多信号采集的原理和实现方案。     

Mechanisms of interaction in acoustic plate mode immunosensors

Acoustic plate mode (APM) sensors have been used to detect immunochemical reactions in on-line measurements. In order to determine the exact mechanisms of interaction involved and to enhance reproducibility, both metallized and non-metallized devices have been investigated. The metallization is found to reduce total frequency shifts by 40–50%, an effect which must be attributed to either acoustoelectric interaction with the protein layer or different mass sensitivities for the different surface boundary conditions. In spite of the lower frequency shifts, metallized sensors may be advantageous for detecting biochemical reactions in ionic solutions because spurious signals are found to be effectively eliminated.     

基于W77E58的金刚石压机测控系统设计

本文研究了金刚石压机测控系统的主要结构,讨论了温度、压力的检测和控制方法,进行了系统的软硬件设计。     

一种新的陀螺振子及工作方式的研究

本文提出了一种新形式的陀螺振子结构,介绍了其工作原理。当陀螺振子在驱动模态谐振时,检测与驱动正交振动位置的振动情况,推导出了两模态振动公式。利用有限元软件建模,对新振子能否满足驱动与检测模态频率相等的灵敏度要求进行仿真验证。     

半胱氨酸修饰的掺硼金刚石电极用于尿酸的测定

在掺硼金刚石电极表面修饰聚半胱氨酸的电极测定尿酸时抗坏血酸和多巴胺的干扰较低。在方波伏安信号中抗坏血酸或多巴胺与尿酸共存检测时尿酸的特征峰电位变化较小(不超过15mV),峰电流变化只有几微安培。利用循环伏安法、方波伏安法对比了修饰电极与没有经过修饰的电极对尿酸的响应,试验了扫描速度、方波振幅、pH值等对修饰电极性能的影响。在最优条件下,得到测定尿酸的线性范围为1.45×10-9～1.16×10-6mol/L。在上述定性定量分析的基础上对未经预处理的儿童肾病病人尿样进行了检测,得到了令人满意的结果。     

聚晶金刚石复合片崩角缺陷视觉检测技术研究

针对目前国内生产聚晶金刚石复合片(PDC)的企业大多数在表面缺陷检测环节严重依赖于人工检测,存在检测效率低、主观性强等问题,提出了一种基于机器视觉的检测方法替代人工检测.将倒角边缘的崩角缺陷作为检测目标,研究崩角图像的表面特征后,提出了在硬件上使用零角度环形光源突出崩角特征,在检测方式上通过阈值分割、中值滤波进行预处理,然后利用最小二乘法拟合获取倒角圆环的圆心位置和小圆半径并建立掩码,最后通过与(AND)运算提取出崩角信息,进行识别和标记.结果显示:实现对图像中的崩角缺陷自动检测和定位,并且判断标准统一.     

Self-adaptation of learning rate in XCS working in noisy and dynamic environments

An extended classifier system (XCS) is an adaptive rule-based technique that uses evolutionary search and reinforcement learning to evolve complete, accurate, and maximally general payoff map of an environment. The payoff map is represented by a set of condition-action rules called classifiers. Despite this insight, till now parameter-setting problem associated with LCS/XCS has important drawbacks. Moreover, the optimal values of some parameters are strongly influenced by properties of the environment like its complexity, changeability, and the level of noise. The aim of this paper is to overcome some of these difficulties by a self-adaptation of a learning rate parameter, which plays a key role in reinforcement learning, since it is used for updates of classifier parameters: prediction, prediction error, fitness, and action set estimation. Self-adaptive control of prediction learning rate is investigated in the XCS, whereas the fitness and error learning rates remain fixed. Simultaneous self-adaptation of prediction learning rate and mutation rate also undergo experiments. Self-adaptive XCS solves one-step problems in noisy and dynamic environments.     

Direct electrochemical detection of sodium azide in physiological saline buffers using highly boron-doped diamond electrodes

Direct detection of sodium azide was examined by using highly boron-doped diamond (BDD) electrodes in some physiological saline buffer solutions. Three important saline buffers, ADA buffer (N-(2-acetamido) iminodiacetic acid), sodium EDTA and imidazole, were investigated. Hydrogen-terminated BDD was fixed for the investigation since it showed much better sensitivity for azide oxidation in comparison with the oxygen-terminated one. Wide range of buffer concentration was examined. A well-separated peak of sodium azide was observed in its mixture with the buffers, resulting in selective sodium azide detection. The current responses were exactly total addition of sodium azide and buffer current responses. The present method was evidenced to be available for direct detection of sodium azide in two samples of commercial diluents for cell counting. A standard addition method was applied. Sodium azide concentrations of 502 and 1355 μg mL⁻¹ were detected in both samples with the R.S.D.s of 0.07 and 2.37%, respectively. Validation was achieved by the comparison with the sample concentrations given by the manufacturer. Simple, selective, good sensitivity and excellent reproducible detection make the diamond electrodes very attractive for numerous electroanalytical applications.     

引压方式动态压力传感器研制

介绍了一种通过引压方式探测动态压力信号的传感器。由于受到被测介质温度高和被测环境空间尺寸小限制,传感器需要通过引压管传递动态工作压力。为了保证引压管在传递动态压力过程中不影响传感器的频响特性,设计了一种阻抗匹配结构,减小了引压结构对传感器动态响应特性的影响,保证了动压传感器的频响特性,该传感器的检测单元包括一个引压管、一个敏感元件、一个电路组件、一个阻抗匹配管。测试结果表明：动压传感器具有（31.5～8000 Hz）频响范围。     

Prediction ability of a lumped-element equivalent-circuit model for thickness-shear mode resonators in liquids

The viscosity-density prediction ability of a lumped-element equivalent-circuit model for a thickness-shear mode resonator operating in Newtonian liquids is examined. The model is a Butterworth-Van Dyke equivalent-circuit modification that describes the near-resonance electrical characteristics of a liquid-loaded resonator. By comparing the relative significance of different load contributions, a simplified liquid-phase lumped-element model is introduced. This model is calibrated with an admittance measurement on a resonator in contact with water. With the calibrated model, the liquid viscosity-density product is predicted from measurements made in aqueous glycerol solutions. These predictions are found to be accurate compared to the literature values. In addition, the predicted value for the average surface roughness of the resonator is consistent with the presented SEM micrographs.     

电梯上高峰动态规划分区控制方法的研究

研究电梯在上高峰模式下,采用动态规划方法进行动态分区的电梯群控方法.将乘客的乘梯时间和候梯时间作为目标函数,在上高峰模式下对电梯群控的各部电梯进行最优分配,达到节能、快速和提高电梯利用率的目的.通过几种群控算法的仿真比较,验证了基于动态规划方法进行动态分区电梯群控方法的良好效果.     

峰值电流模升压转换器的动态斜坡补偿电路设计

基于HHNEC 0.35 μm BCD工艺设计了一种应用于峰值电流模升压转换器的动态斜坡补偿电路.该电路能够跟随输入输出信号变化,相应给出适当的补偿量,从而避免了常规斜坡补偿所带来的系统带载能力低及瞬态响应慢等问题.经Cadence Spectre验证,该电路能够达到设计要求.     

Design,dynamic modelling and experimental validation of a 2DOF flexible antenna sensor

A two-degree-of-freedom flexible antenna sensor platform was designed to physically simulate the ability of a robotic arm, which rapidly reorients and targets itself towards specific surfaces from different approachable angles. An accurate antenna model involves non-linear expressions that represent the system dynamics. Therefore, a comprehensive study along with experimental work has been carried out in order to achieve accurate system identification and validate the dynamic model. The model developed has proven useful in controlling the antenna tip, minimising the effects of the non-linear flexural dynamics and the Coulomb friction. The system was driven by servo motors. Algebraic controllers were developed for the antenna tip to track the reference trajectory. The platform system used encoders to measure the joint angles and a loadcell sensor to obtain the flexible link tip position. To validate the sensory information, the results obtained by the integrated sensors were compared to that of an external camera system.     

Design of sliding mode guidance law with dynamic delay and impact angle constraint

A sliding mode guidance law with dynamic delay and impact angle constraints is designed for the relative motion between the missile and the target in the intercepting plane. First of all, the missile’s first order dynamic delay is involved into the system model to design the guidance law based on sliding mode variable dynamic method. Secondly, the target’s maneuvering is taken as the system disturbance, and a non-homogeneous disturbance observer is applied to estimate such maneuvering in finite time rapidly, which, through dynamic compensation, realizes the missiles precision attack to targets of different maneuvering at a desired line-of-sight (LOS) angle. Finally, numerical simulations are performed to demonstrate the effectiveness of the designed guidance law.

     

多晶SiC薄膜的生长及其压阻特性

在Ａｒ、ＣＨ４的混合气体中用反应性磁控溅射法生长了多品ＳｉＣ薄膜。溅射靶使用了单晶硅片。ＳｉＣ薄膜的生长速率１０～４０ｎｍ／ｍｉｎ。Ａｒ的分压为６０ｍｔｏｒｒ（１ｔｏｒｒ＝１３３．３２２Ｐａ，以下同），ＣＨ４的分压为４０ｍｔｏｒｒ，衬底温度为７５０℃时，薄膜具有显著的多晶特性。杂质浓度、Ｈａｌｌ迁移率、电阻率分别为１０（１８）ｃｍ（－３）、１０ｃｍ（２）／Ｖ·ｓ、１０（－１）１０（－２）Ωｃｍ。压阻系数约为１５。     

钻石琢型的计算机辅助设计软件的设计与应用

作为消费量巨大也是最受欢迎的宝石产品一钻石,现有的琢型已不能满足消费者日趋个性化的需求。本文基于此介绍了钻石琢型设计软件的应用前景,以及初步实现了该软件,目前的测试结果表明,该软件可以作为一套行之有效的设计产品继续发展下去。     

Gas sensors for air quality monitoring: realisation and characterisation of undoped and noble metal-doped SnO2 thin sensing films deposited by the pulsed laser ablation

Undoped and noble metal-doped very thin SnO₂ sensing layers deposited by the pulsed laser ablation (PLA) technique upon micromachined Si substrate heater elements have been extensively characterised. The main objective behind the effort carried out in this work has been the challenging perspective to define a sensing layer technology and a sensor operating mode (continuous (DC) vs. pulsed temperature (PT) mode) which allows the long term measuring and the easy discrimination of very low concentration of benzene by an interfering species like carbon monoxide, both present in the outdoor air. The experimental results reported in this work have shown that combining the sensor technology with a suitable catalytic element (in the present case, gold) and a proper sensor operating mode, very low concentration of benzene can be revealed with a sufficient selectivity towards CO. One of the major problems encountered during the long term test of the sensors has been the loss of the sensitivity to benzene with the time. An attempt has been made to explain the reason of this experimental result. We firmly believe that many factors contribute to it. Among them, the annealing of point defects associated with the oxygen vacancies as well as the loss of the catalytic efficiency by the added Au layer as effect of a possible coalescence of the metal clusters at the sensor working temperature (T400°C). To partially reduce the cluster mobility and to preserve the benzene sensitivity, the last assumption would suggest to operate the sensors, no matter if in DC or in PT mode, at a temperature lower than that used in this work.     

动态环境下有时间窗的成套配送车辆路径问题

为解决成套配送车辆路径优化问题,针对配送线路动态变化的特点进行行程时间分析,根据服务时间窗设计满意度函数,在基本VRP模型中增加满意度目标,建立动态环境下的仿真模型;采用"预优化阶段+实时优化阶段"两阶段求解策略,利用分解法进行问题分解,设计禁忌搜索算法求解,对已产生的路径进行优化调整;仿真计算验证了模型和算法的有效性与研究的实用价值。