抛光液温控装置结构设计及温度场分析

为精确控制超光滑表面抛光过程中抛光液的温度,根据温控基本原理设计温控装置结构.将用UG建立的温控装置模型导入GAMBIT中进行温度场分析.针对装置内部温度分布不均匀问题,对其结构进行优化：在装置内加入导热隔板将其分为工作区和调温区,制冷器被置于调温区内;将温控装置的外形结构加入过渡圆角.结果表明：优化后的温控装置形成内外环流,工作区温度波动范围为±0.01℃,温度分布均匀对称,满足高精度温控的恒温和匀温要求.     

反射炉智能温控系统的研究与展望

从再生铝反射炉的应用现状出发,对我国再生铝单室反射炉的主要工艺流程进行说明,对反射炉温控系统的性能提出了要求.针对单室反射炉对智能温控系统的硬件及算法进行研究,提出针对温控系统所要使用的新型混合智能算法,最后对再生铝单室反射炉温度控制器的发展进行展望.     

一种新型的基于TEC的温控箱设计

提出了一种新型的基于半导体制冷的温控箱,能在较宽的工作温度下给光纤陀螺提供一个稳定的温度环境。在测试过程中,文中所设计的温控箱效果良好,成功地满足了设计使用要求。温控箱具有速度快、精度高、无转动部件等优点,为提高光纤陀螺惯导系统温度稳定性、迅速达到稳定工作状态提供了一种实用方法,也为类似的温控箱结构设计提供了有益的参考。     

基于微控制器的温控风扇的设计

基于微控制器的温控风扇的设计采用微控制器作为微控制器,基于微控制器的温控风扇的设计利用温度DS18B20传感器作为温度采集元件,基于微控制器的温控风扇的设计根据温度DS18B20传感器采集到的温度,通过一个达林顿反向驱动器ULN2803驱动风扇电机.基于微控制器的温控风扇根据检测到的温度与系统设定的温度的比较实现风扇电机的自动启动和停止,基于微控制器的温控风扇的设计根据温度DS18B20传感器采集到的温度变化自动改变风扇电机的转速,同时用lcd1602液晶显示屏显示检测到的温度与设定的温度.     

基于51单片机的智能温控风扇设计

针对传统散热风扇只能依靠人工手动控制且无法精确感知周围环境温度的问题,根据温控风扇的用途,设计了可以检测周围环境温度且能改变室温的智能温控风扇。该设计主要基于51单片机和DS18B20温度传感器,通过温度传感器监测温度,将所监测的温度值返还给单片机,单片机对温度值进行分析和比较,进而控制风扇的转速。该设计能有效地降低室...     

面向皮卫星应用的MEMS陀螺温度控制系统设计

设计了一种面向皮卫星应用的MEMS陀螺温度控制系统,其控制原理为基于ADN8831的TEC温度控制。分析了影响温控系统控制精度的各因素,并且通过Steinhart-Hart方程对热敏电阻的R-T特性进行拟合校准后表明,本温控系统的精度达到±0.03℃。将设计的温控系统应用于面向皮卫星的MEMS陀螺温度控制,通过Allan方差分析MEMS陀螺的误差项。通过不同温度下实验得出,当该温控系统存在时,零偏不稳定性和速率随机游走得到了不同程度的改善,验证了温控系统的有效性,满足了皮卫星体积小、功耗低的要求。     

时分复用光纤光栅传感阵列中DFB激光器的高精度温控设计

针对时分复用光纤光栅(TDM-FBG)传感阵列中使用的分布反馈(DFB)激光器高波长稳定度的要求,设计了一个高精度的DFB温控方案,包括温度测量与设定、热敏电阻线性化、PID补偿回路、H桥驱动、温度电压采集与显示等。使用DFB内置的热敏电阻和半导体制冷器(TEC)对温控电路进行了测试,其精度在180s内达到±0.04℃,温控后激光器温度变化引起的应变测量误差为±3.4με左右,满足TDM-FBG传感阵列的要求。     

基于FPGA的弹载数模混合采集存储系统设计

针对弹载试验过程中传感器输出方式的不同,设计了一种基于FPGA的弹载数模混合采集存储系统。系统选用Spartan-II系列的XC2S100作为核心处理器,采用16 bit的高精度A/D转换芯片ADS8365实现模数转换。FPGA控制将传感器输出的数字量和模拟量采集编码后存储到固态存储器FLASH中,最后,为了模拟系统在飞行过程中的状态,将系统放置在三轴位置速率摇摆温控转台上进行验证,试验结果证明,所设计的数模混合采集存储系统正确可靠,具有一定的工程应用价值。     

基于单片机的恒温连续可调型温控系统

提出了一种基于单片机的温控系统软件和硬件的设计方案.本设计采用8位单片机和16位A/D变换器相组合构成温度采集系统进一步提高系统的性价比.采用数字PID控制使温控精度在300-500℃范围内达到1℃,并可实现温度设定值的连续可调.采用铂电阻温度测量电路,并利用软件对测量精度进行自校准;通过电压前馈控制减少电网干扰.设计中还加入了光电隔离措施及过热自动保护和报警功能,增强了系统的安全性能.     

高精度实时荧光定量PCR温控系统的设计与仿真

针对目前国产实时荧光定量PCR温控系统升降温速度慢和精度低的问题,提出了一种改进的模糊自适应PID算法。首先根据热力学公式,建立了实时荧光定量PCR温控系统的数学模型,在模糊自适应PID算法的基础上加了一个在线调整量化因子和比例因子的智能调整器,根据设定的模糊控制规则实时优化PID参数、量化因子和比例因子,由PID控制器和智能调整器控制实时荧光定量PCR的温度。采用Simulink对PCR温控系统进行仿真,结果表明：设计的模糊自适应PID控制器控制精度达到[0.1 ℃],快速稳定以后,能达到[0.01 ℃],升降温速度大于等于[7.0 ℃/s],完全能够满足实时荧光定量PCR温控系统对温度精度和升降温速度的要求。     

Predictive hybrid control of the supermarket refrigeration benchmark process

Predictive control is applied to a supermarket refrigeration process in which all actuators are on/off devices. This process has been proposed as a benchmark for the evaluation of hybrid control methods. It is shown that decentralized predictive control of display case temperatures, when combined with predictive control of suction manifold pressure, can greatly reduce or eliminate on/off compressor cycling. The strategy is scalable to large systems. Results are presented for an application involving 10 display cases and six compressors. Traditional hysteresis control causes synchronization of display case temperature oscillations. The proposed predictive approach includes desynchronization, which is shown to be necessary for minimization of compressor cycling. Finally, it is shown that the minimum possible number of compressor cycles can be estimated. This limit on control system performance is imposed by process design and operating conditions. It is also shown that the recommended predictive control strategy operates close to the minimum possible number of compressor cycles for the benchmark process.     

Cooling vests with phase change material packs: the effects of temperature gradient,mass and covering area

Phase change material (PCM) absorbs or releases latent heat when it changes phases, making thermal-regulated clothing possible. The objective of this study was to quantify the relationships between PCM cooling rate and temperature gradient, mass and covering area on a thermal manikin in a climatic chamber. Three melting temperatures (24, 28, 32°C) of the PCMs, different mass, covering areas and two manikin temperatures (34 and 38°C) were used. The results showed that the cooling rate of the PCM vests tested is positively correlated with the temperature gradient between the thermal manikin and the melting temperature of the PCMs. The required temperature gradient is suggested to be greater than 6°C when PCM vests are used in hot climates. With the same temperature gradient, the cooling rate is mainly determined by the covering area. The duration of the cooling effect is dependent on PCM mass and the latent heat.

Statement of Relevance: The study of factors affecting the cooling rate of personal cooling equipment incorporated with PCM helps to understand cooling mechanisms. The results suggest climatic conditions, the required temperature gradient, PCM mass and covering area should be taken into account when choosing personal PCM cooling equipment.     

Cooling Load Density Optimization of an Irreversible Simple Brayton Refrigerator

The performance optimization of an irreversible simple Brayton refrigerator coupled to constant-temperature heat reservoirs is carried out by taking the cooling load density, i.e., the ratio of cooling load to the maximum specific volume in the cycle, as the optimization objective using finite-time thermodynamics (FTT) or entropy generation minimization (EGM) in this paper. The analytical formulae about the relations between cooling load density and pressure ratio, as well as between coefficient of performance (COP) and pressure ratio are derived with the heat resistance losses in the hot- and cold-side heat exchangers, and the irreversible compression and expansion losses in the compressor and expander. The influences of the effectiveness of the heat exchangers, the temperature ratio of the reservoirs, and the efficiencies of the compressor and expander on the cooling load density versus COP are provided by numerical examples. The cooling load density optimization is performed by searching the optimum pressure ratio of the compressor, and searching the optimum distribution of heat conductance of the hot- and cold-side heat exchangers for the fixed total heat exchanger inventory. The influences of some design parameters, including the effectiveness of the heat exchangers between the working fluid and heat reservoirs, the efficiencies of compressor and expander, the temperature ratio of heat reservoirs, on the maximum cooling load density, the optimum heat conductance distribution and the optimum pressure ratio are provided by numerical examples. The refrigeration plant design with optimization leads to a smaller size including the compressor, expander, and the hot- and cold-side heat exchangers.     

基于CAN总线的干式变压器智能温度控制器设计

介绍一种具有CAN总线接口的干式变压器智能控制器。该控制器可同时检测多路温度,控制变压器冷却风机启、停。通过人机接口可方便地设定报警及跳闸阀值。系统性能稳定,抗干扰能力强。     

高速电主轴瞬态温度场分析与测试

研究数控机床主轴温度优化控制问题,高速电主轴系统热变形影响机床加工精度。由于高速电主轴是一个复杂的非线性系统,对温度优化控制较困难。为精确了解高速电主轴系统瞬态温度场分布,采用MSC.Marc软件接触热阻,以多体接触的方式,对电主轴系统不同转速工况下进行有限元仿真分析,并通过现场验证仿真结果。结果表明,系统温度场分布不均,冷却水将系统分成高、低温区域;定子温度随转速非线性变化,转速3000rpm以上温度增长较快。以分析和测量结果为基础,利用冷却水降温。根据定子发热量随转速的变化规律,实时进行控制。测试结果证明,对高速机床温度测量精度效果好,为设计提供了依据。     

基于神经网络的变频空调控制系统

基于神经网络的变频控制空调可以根据实际环境与室内需求的不同,连续地、动态地、适时地按需要输出,改进了一般定速空调器在实际应用中室内机的输出滞后于压缩机,而室内空气参数的滞后则更大的不足.采用了神经网络的误差反传（BP）算法,可以快速、准确的对从实际环境中获得的数据进行综合、分析,得出正确的结论,从而通过控制单元调节压缩机、风机和电子膨胀阀,使其根据现状迅速地做出反应,达到智能控制的效果,具有先进性、经济性、和实用性.     

Optimal on–off control of refrigerated transport systems

This paper presents a hysteretic on–off control scheme with optimization algorithms for temperature regulation in refrigerated transport systems. A nonlinear dynamic refrigerated transport system model, which consists of a refrigeration unit and a cargo space, is developed. The model serves as an analytical tool for control design. An optimal on–off control strategy is developed based on the time domain analysis of the temperature oscillations. A cost function involving temperature variations from the set-point, energy consumption and average compressor on–off cycling frequency is introduced for minimization. Choices of weighting values in the cost function give the flexibility of the control approach to meet different requirements. Simulation examples are presented that demonstrate the ability and robustness of the proposed method in achieving tighter temperature regulation and higher system efficiency control in transport refrigeration systems. The simulations are augmented by experimental validation via a novel hardware-in-the-loop load emulation approach.     

Bifurcation control of rotating stall with actuator magnitude and rate limits: Part II—control synthesis and comparison with experiments

Operability enhancement is defined as the extension of operating range for which fully developed rotating stall is avoided. It is proved that the rate-saturated control law is the optimal control that maximizes the operability enhancement. For the controlled system with the rate-saturated controller, analytic formulas are derived for the operability enhancement as a function of noise level, actuator saturation limits, and the shape of the compressor characteristic, which is the major nonlinearity in the model. The shape of the compressor characteristic, especially the unstable part, is critical to the rate required for robust operability near the peak for the closed-loop system. Experiments are carried out on a single-stage low-speed axial compressor using different levels of steady air injections to generate compressor characteristics with different shapes. The rate requirement predicted by the theoretical formulas agrees qualitatively with experiments and simulations of a higher order model (37 states).     

基于自适应LS-SVM的柴油机废气再循环冷却控制系统设计

针对当前柴油机废气再循环冷却控制系统受到时滞问题影响,导致系统开度走势与设定走势不一致、废气再循环效果差的问题,提出基于自适应LS-SVM的柴油机废气再循环冷却控制系统;以AT89C51单片机40针作为电控单元核心部件,利用位置传感器向系统发送负载信号,利用温度传感器来传输信号并反馈至D/A转换器;在D/A转换器中,反馈信号以串行或并行方式进入寄存器,并在转换后输出电流电压,控制系统阀门在排气再循环时的开启;伺服泵采用冷却系统,为系统提供液压动力源;利用自适应LS-SVM原理计算柴油机废气再循环冷却控制目标边界值,在最小二乘支持向量机基础上,利用求解线性方程组进行优化,消除了控制误差;根据控制差的大小,调整控制系统的输出值;由试验结果可知,该系统开度走势与设定开度走势一致,且与设定开度误差为1开度,说明使用该系统具有良好稳态特性,有效克服了系统中时滞问题,废气再循环效果较好。     

PLC在原料气压缩机控制系统中的应用研究

根据原料气压缩机的工作过程,采用西门子PLC S7-300作为下位机,触摸屏作为人机界面,构成压缩机组控制系统,由PLC对压缩机的压力、温度及其他参数等信号进行采集、控制、监控及联锁保护和报警,实现了自动化.组态软件制作的监控操作界面,操作直观方便.实际运行表明,采用该控制系统提高了生产效率,取得了良好的经济效益.