高稳定度激光光源数字温控技术

通过测量激光二级管(LD)制冷模块的响应曲线,采用曲线拟合的方法建立其数学模型,并针对该模型没计比例-积分-微分(PID)控制器控制LD的温度。实际测试证明该PID控制器能有效补偿制冷模块的相位延时,使LD的温度稳定度达到±0.05℃。     

An infrared scanning technique for the determination of temperature profiles in microcircuits

Circuit reliability and performance, particularly in high-density microcircuits, are affected by temperature. Therefore, a knowledge of the heat transfer paths and temperature distribution are of prime importance in topological design for efficient circuit performance. The method of thermal profiling described uses infrared scanning. The method is direct, rapid, and nondestructive, and the temperature profile is unaffected by the measurement. The effects of heat sinks, heat sources, and unusual geometrical patterns are automatically taken into account. The "heart" of the infrared scanning system is a photosensitive element of single-crystal indium antimonide with a long wave cutoff near 6 microns. The system has successfully determined isothermal patterns from 55°C to >250°C in thin-film tantalum microcircuits having linewidth patterns as small as 2 mils. Isothermal patterns of various geometries are shown to illustrate how the area and shape of resistors affect the thermal pattern and the temperature of the hottest part. Life data correlating the temperatures at the hottest parts with operating stability of thin-film resistive networks is presented. Through the correlation of temperature profiles with storage life tests, the potential exists for greatly reducing the amount of costly life testing of microcircuits for every new bias condition and circuit. Although emphasis is placed on thin-film microcircuits, a thermal profile of a solid silicon microcircuit is presented to indicate usefulness of the infrared scanning technique for temperature profiling of other types of microsystems.     

Decentralized optimal flow control with constrained source rates

We study optimal flow control in multiservice networks, in which users (controllers) optimize their performance objectives in a decentralized manner. We adopt a model that differs from previously considered ones in that a user's strategy (viz., flow or average rate) is constrained between two numbers: those are specified by the user's quality of service (QoS) requirements or by the user's technology. Adopting the generalized power as the performance measure, we prove existence and uniqueness of the Nash equilibrium point (NEP) and suggest a simple algorithm to determine this NEP     

An analytical quasi-saturation model considering heat flow for aDMOS device

This paper reports an analytical quasi-saturation model considering heat flow for a DMOS device. As verified by the PISCES results, the analytical model, which considers heat flow provides a good prediction of the much worse quasi-saturation behavior due to the elevated lattice temperature. This is a result of the limited heat sinking capability of the thermal contact node. Based on the analysis, for a DMOS device operating with a contact thermal resistance of less than 10⁴ K/W, the drain current at quasi-saturation is found acceptable with a lattice temperature below 350 K     

激光辐照温度场计算中的"像热源"研究

激光热作用研究中 ,通常只能采用纯数值计算方法研究异形工件激光热处理温度场 ,本文介绍轴对称像热源处理边界问题的半解析计算方法并给出实验证明。该方法适用于任意分布光束的热作用计算 ,当工件的局部边界由非正交平面构成时 ,可以获得满意的计算结果     

掺铒光纤放大器泵浦光源温控系统设计

所描述的泵浦光源温控系统,以飞思卡尔的MC9S12系列McU芯片作为开发平台,基于成熟的PID控制算法,大胆引入了闭环负反馈控制结构,它所输出的控制信号,不仅可以成功地驱动TEC电路,而且还可以使其在20s内将温度调控到目标值.在精度方面,达到了±0.1℃的工业级精度,完全满足设计指标的要求.     

卫星的表面温度与红外辐射特性

建立了卫星温度场与红外辐射特性的理论计算模型.首先利用有限元法求解瞬态热平衡方程,得到了卫星的温度场分布,然后根据卫星的表面温度分布,在3～6μm和6～16μm波段计算了卫星的红外辐射出射度,并对其变化规律及影响因素进行了详细的分析.最后将卫星视为空间点目标,计算比较了卫星处于日照区和地影区时两个波段的红外辐射强度空间分布.该研究结果对于空间目标的红外探测与识别具有参考价值.     

Impact of nonlinear heat transfer on temperature control inregional hyperthermia

We describe an optimization process specially designed for regional hyperthermia of deep-seated tumors in order to achieve desired steady-state temperature distributions. A nonlinear three-dimensional heat transfer model based on temperature-dependent blood perfusion is applied to predict the temperature. Using linearly implicit methods in time and adaptive multilevel finite elements in space, we are able to integrate efficiently the instationary nonlinear heat equation with high accuracy. Optimal heating is obtained by minimizing an integral objective function which measures the distance between desired and model predicted temperatures. A sequence of minima is calculated from successively improved constant-rate perfusion models employing a damped Newton method in an inner iteration. We compare temperature distributions for two individual patients calculated on coarse and fine spatial grids and present numerical results of optimizations for a Sigma 60 Applicator of the BSD 2000 Hyperthermia System.     

物联网技术在道路运输领域中的应用研究

本文主要研究了道路运输领域中物联网技术的应用,利用物联网技术来管理道路各种车辆的进出和行驶,有利于车辆套牌问题、车辆使用虚假牌照问题的解决,有利于规范道路使用,提高道路使用效率.     

高精度星载微波定标源黑体温度测量控制系统的设计

微波辐射定标源作为微波辐射计的重要载荷设备,可校准微波辐射计输入亮温度与输出量值间的关系,实现微波辐射计灵敏度、线性度和稳定度等参数的标定。针对辐射源黑体及其测温传感器,设计了一种在轨温度测量与控制电路,用于温度信号的检测与调理、低通滤波、数据采集、温度数据处理以及温度的稳定控制。地面测试与在轨运行均表明,系统满足星载微波辐射计的设计要求,具有高精度、高可靠性的特点。     

Distributed source control: a network access control for integratedbroadband packet networks

The authors propose a congestion control strategy called distributed source control (DSC), designed to address the integration of diverse traffic types in broadband packet networks. DSC is a rate-based network access control implemented at the asynchronous transfer mode (ATM) layer as a feedforward control, in conjunction with an adaptive end-to-end control between network edges. The authors examine the performance of high-speed data traffic such as large file transfers, still images, and document retrievals. The authors study DSC's integrability with real-time traffic such as voice and video. With the help of a simulation model of a broadband packet network (150 Mb/s), the authors quantify the improvement in network performance due to DSC. An analytic model for an access node under DSC is developed, and guidelines for sizing of buffers in the switch and for choosing the end-to-end window size are provided     

Characteristics of a GaAs spontaneous infrared source with 40 percent efficiency

The external quantum efficiency of a forward-biased GaAs p-n junction device selected for high efficiency measures 40.5, 32, and 7.3 percent at 20, 77, and 295°K, respectively. The optical exit path is through bulk material doped to a 10¹⁷donors/cm²level. The infrared emission is measured directly with a silicon solar cell. The effective transmissivity of the GaAs bulk device material is measured to be 42 and 8.3 percent at 77 and 295°K, respectively. The corresponding values for the internal quantum efficiency are 76 and 88 percent. The primary optical rise time measured for high level current pulsing conditions is 0.6 and 1.6 ns at 77 and 295°K, respectively.     

An evaluation of flow control in group communication

Group communication services have been successfully used to construct applications with high availability, dependability, and real-time responsiveness requirements. Flow control techniques enable group members to manage their local buffers, which they use to temporarily store multicast updates. Despite buffer overflow being one of the main causes of process failures, flow control has not been studied much in the literature. We study different flow control techniques used in some of the group communication services and present two generic flow control techniques: a conservative and an optimistic technique. All existing flow control techniques for group communication can be classified as either conservative or optimistic. We then present discrete event simulation results that compare the effect of these two generic flow control techniques on the performance of two, different atomic multicast protocols, a positive acknowledgment protocol and a negative acknowledgment protocol, under several different operating conditions. Based on the study of differed existing flow control techniques for group communication and the results obtained from the simulation experiment, we provide some design guidelines for the design and implementation of a suitable flow control technique for a given group communication service     

ABR业务流量控制的一种智能机制

本文提出了一种ＡＢＲ业务模糊流量控制机制,仿真结果表明它有效地避免了网络阻塞,在网络的吞吐量上要高于强比例速率控制算法（ＥＰＲＣＡ）。该机制与连接业务的特性无关,且不需要改变有关ＡＢＲ闭环反馈的流量控制结构,这为算法的实际应用提供了前提。     

Microcomputer control and data analysis for a far infrared Fourier spectrometer

A commercial general-purpose microcomputer is used to provide real-time experimental control, data acquisition and data analysis for a far infrared Fourier spectrometer. The interfacing and programming procedures are described. The microcomputer gives excellent performance at a low cost.     

腐蚀生产线上槽液流量的控制方法及应用

铝电解电容器阳极箔的腐蚀生产线上 ,主腐蚀槽槽液的流量是一个关键控制量。根据法拉第电解定律 ,定量地阐述了主腐蚀槽槽液流量的控制方法。结合实际情况 ,讨论了该控制方法的局限性和有效性。     

Fiber-optic Fabry-Perot temperature sensor using a low-coherencelight source

An interferometric fiber-optic sensor using a light-emitting diode (LED) as the optical source is analyzed and demonstrated. The sensor arrangement employs two Fabry-Perot interferometers (FPIs) in series, one for sensing and one which serves as a reference. The optical output from the LED is spectrally modulated by reflection from the sensing FPI. Then, reflection or transmission by the reference FPI produces an interferometric beat response similar to that observed when a laser is used with the sensing interferometer alone. Best fringe visibility is obtained when the optical path lengths of the two interferometers are matched, and the fringes disappear when the path length difference becomes substantially greater than the coherence length of the LED