溶氧传感器的温度特性研究及其补偿

分析了溶液中氧的溶解特性,对可高温灭菌的极谱型溶氧电极的工作原理进行了阐述,分析了溶氧传感器的温度特性.采用溶氧电极温度特性公式近似温度所引起的全部测量误差,试验结果验证了该方法的可行性.根据以上的分析,得出了温度补偿策略,试验数据进一步表明温度变化对溶氧测量有着重要的影响,文中提出的温度补偿策略简便有效,可以取得与国外先进仪表相似的性能,极大地降低控制系统成本.     

水下储油保温材料热传导测试技术研究

为了实现水下储油保温材料保温性能的高效测试,对水下保温材料热传导特征进行了理论分析,对热脉冲双探针--DPHP(dual-probe heat-pulse)热导率快速测量理论方法进行了研究.利用该方法对水下保温材料进行了大量测试实验.测试结果表明,其平均测量速度≤40 s,热导率精度可以达到±0.05,保温材料水下热传导变化规律与理论分析结果一致,测量速度和精度有了较大提高.     

拓扑信息采集系统的分布式轻载监测技术

分布式系统软件的运行负载和任务完成状态信息在系统改进和新结构设计中具有重要作用。提出用于大规模网络拓扑信息采集系统的分布式轻载监测技术,采用基于Manager/Agent模型、多线程探针的信息监测技术和基于简单网络管理协议的Agent技术,采集并传输负载信息和任务完成状态信息。该方法具有低负载、对系统运行干扰小、时效性强和高扩展性的特点。     

基于最小二乘法的月球探测器自主导航

对于地月转移轨道的月球探测器,其受力复杂,轨道动力学方程难以精确建立,因此难以应用已有的基于轨道动力学方程的滤波方法对其进行自主导航.文中提出了以太阳和恒星的天文信息为观测量,采用迭代最小二乘法进行纯几何解析定位来实现月球探测器自主导航的方法.最后还对定位结果的优化的进行了研究.通过数学仿真分析了敏感器精度、观测星个数等因素对定位精度的影响,结果表明这种方法简单可靠,可以作为深空探测自主导航的滤波方案的初值.     

Room temperature nitrogen dioxide chemresistor using ultrathin vanadyl-phthalocyanine film as active layer

A room temperature nitrogen dioxide (NO₂) chemresistor using 1.8 nm ultrathin vanadyl-phthalocyanine (VOPc) film as active layer has been prepared by Weak Epitaxy Growth (WEG) method. Its gas sensing properties to NO₂ have been compared with a 7 nm polycrystalline VOPc chemresistor. The ultrathin film device shows stronger response and better recovery character. Further results reveal that the two-dimensional transport film provides an effective charge transfer system after NO₂ adsorption and it gets rid of bulk diffusion at the same time. Kelvin probe force microscopy (KPFM) results suggest that grain boundaries are easily doped by analyte but is slow in desorption compared with crystal grains. The ultrathin film device shows advanced sensing mechanism compared with the polycrystalline film.     

非侵入式激光探针装备故障注入技术研究及应用

针对装备大规模集成电路测试性验证与评估需求,突破传统方式的故障注入难、耗资耗时等限制,开展半侵入式装备激光探针故障注入技术研究及应用;首先,研究了装备传统物理故障注入技术,分析了脉冲激光瞬态故障注入方式的可行性及作用机理;然后,建立了脉冲激光瞬态故障注入的能量传输模型,提出了基于线性传输和体积传输的脉冲激光能量计算方法;最后进行了试验验证;试验表明,该方法成功实现了典型故障模式的准确复现,可精确定位芯片内薄弱部位以指导装备优化设计.     

Autonomous robot calibration using a trigger probe

This paper presents a new robot autonomous calibration method using a trigger probe. The robot grips a simple probe (which was manufactured as a standard end-effector tool) automatically to touch constraint planes in a workspace (the locations of the constraint planes are not necessarily known exactly). The robot internal sensor measurements are recorded for kinematic calibration while the tip-point of the probe is in contact with the constraint plane. The kinematic constraint conditions are obtained from the known shape of the constraint surface, rather than from the measured reference locations in a workspace. The new method eliminates any use of external measuring devices for robot end-effector location measurements for robot calibration; thus it is suitable for a periodic robot re-calibration in a shop-floor environment. Both simulation and experimental results for a six degree-of-freedom (DOF) PUMA robot are given in this paper. The evaluation results using an external precision measuring device — Coordinate Measuring Machine(CMM) — are also presented.     

Development and experimental characterization of micromachined electromagnetic probes for biological manipulation and stimulation applications

We present the design, fabrication and experimental characterization of a new micromachined electromagnetic probe, which can be readily adapted to various biological manipulation and stimulation applications. The micro electromagnetic probe consists of a protruding (out-of-chip), sharp Permalloy needle embedded into a three-dimensional gold conducting coil. The probe fabrication is carried out using traditional surface micromachining processes coupled with assembly techniques. This hybrid approach significantly reduces fabrication difficulties and provides a simple and straightforward technique to realize integrated core-coil geometries. Furthermore, by using a scanning Hall probe microscope (SHPM), a comprehensive, high-spatial resolution characterization of the probe performance (e.g. peak magnetic intensity and spatial field distribution) is achieved for the first time. The manipulation of sub-micron sized magnetic particles with the developed micro electromagnetic probe is also demonstrated.     

原油含水率测量仪的研究

研究电容测量原油含水率的原理,采用开关电容等变换电路,完成电容到频率的转换,经ＭＣＳ—５１单片机系统处理,在线测量０％～３１％和 ６０％～１００％原油含水率时的精度达到０．５％,含水率在３０％～６０％时的精度达到１％．本文介绍开关电容等变换电路的原理及特点,给出仪器的含水率测量实验结果．     

A new dual C‐shaped rectangular dielectric resonator based antenna for wideband circularly polarized radiation

This article presents a new dual C‐shaped rectangular dielectric resonator (DR) based antenna for generation of wideband circularly polarized (CP) radiation. The proposed antenna comprises of a pair of C‐shaped rectangular dielectric DR and a metal strip with a coaxial probe. By utilization of a metal strip at the side surface of C‐shaped rectangular DR, the wideband CP radiation is achieved from the proposed dielectric resonator antenna (DRA). Fundamental orthogonal modes (TE^x_δ11 and TE^y_1δ1) are excited using the rectangular DRA with a metal strip for the generation of CP fields. The proposed antenna with dual C‐shaped rectangular CP DRA provides the measured ?10 dB reflection coefficient bandwidth of 30.07% (3.22 GHz‐4.36 GHz) with measured 3‐dB axial ratio bandwidth of 14.81% (3.25 GHz‐3.77 GHz) at the boresight. The proposed antenna covers the useful Wi‐MAX band.     

分布式网络故障监测的探针部署方法

在基于主动探针的网络故障管理中,首要的是确定监测探针的部署.不确定性会对监测探针的选取带来影响.为了降低这种影响,采用概率依赖模型为主动探针选取路由,提出了不确定环境下的监测探针部署方案.利用该方案在网络中部署探针对网络进行主动探测,能以较小的代价尽早定位网络中的故障.实验表明本文的探针选择算法可以有效节约探针开销,且...     

Transfer of learning in virtual environments: a new challenge?

The aim of all education is to apply what we learn in different contexts and to recognise and extend this learning to new situations. Virtual learning environments can be used to build skills. Recent research in cognitive psychology and education has shown that acquisitions are linked to the initial context. This provides a challenge for virtual reality in education or training. A brief overview of transfer issues highlights five main ideas: (1) the type of transfer enables the virtual environment (VE) to be classified according to what is learned; (2) the transfer process can create conditions within the VE to facilitate transfer of learning; (3) specific features of VR must match and comply with transfer of learning; (4) transfer can be used to assess a VE’s effectiveness; and (5) future research on transfer of learning must examine the singular context of learning. This paper discusses how new perspectives in cognitive psychology influence and promote transfer of learning through the use of VEs.     

Loop shaping design related to LQG/LTR for SISO minimum phase plants

One method of model-based compensator design for linear systems consists of two stages: state feedback design and observer design. A key issue in recent work in multivariable synthesis involves selecting the observer (state feedback) gain so that the final loop transfer function is the same as the state feedback (observer) loop transfer function. This is called loop transfer recovery (LTR)(Athans and Stein 1987, Kazerooni and Houpt 1986, Kazerooni et al. 1985, Doyle and Stein 1981). This paper shows how identification of the internal mechanism of the LTR provides simple design rules with little algebra for single-input single-output (SISO) systems. In the SISO case, the LQG/LTR reduces to computation of a compensator that shapes the loop transfer function by (i) cancelling the zeros of the plant with the compensator poles, and (ii) locating a new set of zeros for the compensator to shape the loop transfer function.     

Approximated modeling and minimal realization of transfer function matrices with multiple time delays

The modeling and minimal realization techniques for a specific multiple time-delay continuous-time transfer function matrix with a delay-free denominator and a multiple (integer/fractional) time-delay numerator matrix have been developed in the literature. However, this is not the case for a general multiple time-delay continuous-time transfer function matrix with multiple (integer/fractional) time delays in both the denominator and the numerator matrix. This paper presents a new approximated modeling and minimal realization technique for the general multiple time-delay transfer function matrices. According to the proposed technique, an approximated discrete-time state-space model and its corresponding discrete-time transfer function matrix are first determined, by utilizing the balanced realization and model reduction methods with the sampled unit-step response data of the afore-mentioned multiple time-delay (known/unknown) continuous-time systems. Then, the modified Z-transform method is applied to the obtained discrete-time transfer function matrix to find an equivalent specific multiple time-delay continuous-time transfer function matrix with multiple time delays in only the inputs and outputs, for which the existing control and design methodologies and minimal realization techniques can be effectively applied. Illustrative examples are given to demonstrate the effectiveness of the proposed method.     

Visibility-driven PET-CT visualisation with region of interest (ROI) segmentation

Multi-modality (MM) positron emission tomography-computed tomography (PET-CT) visualises biological and physiological functions (from PET) as region of interests (ROIs) within a higher resolution anatomical reference frame (from CT). The need to efficiently assess and assimilate the information from these co-aligned volumes simultaneously has stimulated new visualisation techniques that combine 3D volume rendering with interactive transfer functions to enable efficient manipulation of these volumes. However, in typical MM volume rendering visualisation, the transfer functions for the volumes are manipulated in isolation with the resulting volumes being fused, thus failing to exploit the spatial correlation that exists between the aligned volumes. Such lack of feedback makes MM transfer function manipulation complex and time consuming. Further, transfer function alone is often insufficient to select the ROIs when they have similar voxel properties to those of non-relevant regions. In this study, we propose a new ROI-based MM visibility-driven transfer function (m ²-vtf) for PET-CT visualisation. We present a novel ‘visibility’ metric, a fundamental optical property that represents how much of the ROIs are visible to the users, and use it to measure the visibility of the ROIs in PET in relation to how it is affected by transfer function manipulations to its counterpart CT. To overcome the difficulty in ROI selection, we provide an intuitive ROI selection tool based on automated PET segmentation. We further present a MM transfer function automation where the visibility metrics from the PET ROIs are used to automate its CT’s transfer function. Our GPU implementation achieved an interactive visualisation of PET-CT with efficient and intuitive transfer function manipulations.     

基于图知识迁移的蚁群算法参数选择

同时考虑蚁群算法的所有运行参数,提出一种基于图知识迁移的蚁群算法参数选择方法．首先,将包含知识（蚁群算法的运行参数）的源任务映射到一个高维的迁移空间,并通过迁移权值连接不同的源任务,构造一个模型迁移图;然后,扩展模型迁移图使其包含目标任务,并利用图论的知识学习迁移函数;最后,通过最小二乘法自主地给目标任务分配一个优化的运行参数组合．机器人路径规划问题的仿真结果验证了该方法的智能性、快速性与合理性．     

Computation of analytical expressions for transfer functions

A new method for computing transfer functions of linear time-invariant multi-variable control systems is presented. This method has the following attractive features: (i) it produces analytical expressions for transfer functions, (ii) computations are inherently parallel and can be implemented, for instance, on parallel processors with a fine-grain architecture, (iii) calculations of transfer functions are reduced to two well-studied computational problems: solution of simultaneous linear equations and the fast Fourier transform (FFT), and (iv) state-variable formulations can be avoided. Theoretical conclusions are demonstrated with numerical examples.     

Heat transfer in microchannel devices using DSMC

The heat transfer characteristics of supersonic flows in microchannels is studied using direct simulation Monte Carlo (DSMC) method. The velocity components and the spatial coordinates of the simulated particles are calculated and recorded by using a variable-hard-sphere (VHS) collision model. The effects of Knudsen number (Kn) on the heat transfer of the microchannel flows are examined. The results show that the magnitude of the temperature jump at the wall increases with increasing Kn. The heat transfer to the isothermal wall is found to increase significantly with Kn. The possible causes for the increase of wall heat transfer are discussed     

Input/output structure of the infinite horizon LQ bumpless transfer and its implications for transfer operator synthesis

The steady‐state input/output structure of the infinite horizon LQ bumpless transfer topologies for strictly proper controllers is analyzed. It is found that in these topologies (1) the steady‐state gain of the transfer function from the output of the online controller to that of the offline one is unity/asymptotically unity, and (2) the steady‐state gain of the transfer function from the input of the online controller to the output of the offline one is zero/asymptotically zero, for essentially all strictly proper controllers with the input dimension being no less than the output one. These facts (1) reveal the steady‐state gain structure of the closed‐loop transfer matrix in the standard LQ tracking problems, (2) demonstrate that the LQ bumpless transfer technique solves the ideal bumpless transfer problem for controllers with an integrator in each of their output channels, (3) reveal the structure of unavoidable signal discontinuities in the controller input/output upon transfer between controllers with non‐integrating channels, and (4) provide guidance for minimizing the above signal discontinuities and the resulting bumps in the plant output in bumpless transfer synthesis. Copyright © 2009 John Wiley & Sons, Ltd.     

Data Transfer Over the Internet for Real Time Applications

Efficient real time data exchange over the Internet plays a crucial role in the successful application of web-based systems. In this paper, a data transfer mechanism over the Internet is proposed for real time web based applications. The mechanism incorporates the extensible Markup Language (XML) and Hierarchical Data Format (HDF) to provide a flexible and efficient data format. Heterogeneous transfer data is classified into light and heavy data, which are stored using XML and HDF respectively; the HDF data format is then mapped to Java Document Object Model (JDOM) objects in XML in the Java environment. These JDOM data objects are sent across computer networks with the support of the Java Remote Method Invocation (RMI) data transfer infrastructure. Client's defined data priority levels are implemented in RMI, which guides a server to transfer data objects at different priorities. A remote monitoring system for an industrial reactor process simulator is used as a case study to illustrate the proposed data transfer mechanism.