共查询到20条相似文献,搜索用时 15 毫秒
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Abstract In this study, neuro-fuzzy control of a thermoelectric head cooler system (thermoelectric helmet) is developed for brain hypothermia applications. Hypothermia is a medical treatment method of protecting the brain, in which the temperature of the brain drops below the critical level for reducing oxygen consumption of tissues. The brain should be kept at a certain temperature by a suitable control for hypothermia applications. The temperature of the thermoelectric head cooler system changes according to the current intensity supplied. The control of the thermoelectric head cooler system was performed according to the initial membership functions, which was determined by an expert using fuzzy logic control. The system was modeled by an adaptive neuro-fuzzy inference system (ANFIS). The data were then entered into the system and new membership functions were determined. By this way, learning ability of the artificial neural network and the abilities of fuzzy logic, such as decision making, were combined and a more effective solution was developed. The system software can be reprogrammed with the new membership functions. 相似文献
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多级半导体制冷器设计 总被引:2,自引:0,他引:2
文中主要介绍了半导体制冷器的基本原理及其应用,并对涉及到多级制冷器的有关公式进行了推导,文章最后得出了关于多级半导体制冷器的一些重要结论。 相似文献
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基于微机电系统技术的微型热电致冷器研究进展 总被引:2,自引:2,他引:0
介绍热电材料、热电器件的原理及发展历史,从材料及结构两方面,对基于微机电系统加工工艺的微型热电致冷器的最新研究进展进行综述,比较不同材料及不同结构的性能特点,对块体热电材料和低维热电材料的研究进展进行介绍,着重分析超晶格薄膜材料及Cross-Plane型器件,指出研究具有更高优值系数的新型材料,在维持Seebeck系数不变的同时提高电导率并降低热导率,及采用新的加工工艺优化致冷器的结构,减小接触电阻、接触热阻等,是提高热电致冷器性能的有效手段。 相似文献
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冷凝露点法是一种高精度的食品水分活度检测方法,温度控制是其关键技术之一。本设计采用最新型Cortex-M0内核芯片LPC1114作为控制单元,选用半导体制冷器和加热器作为温度控制元件,运用数字PID智能算法进行温度控制。可用于水分活度测量辅助实验,精度高、响应快,取得良好的控制效果。 相似文献
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Mária ?arnogurská Miroslav P?íhoda Ji?í Molínek 《Journal of Mechanical Science and Technology》2011,25(11):2935-2941
An original method for estimating fouled deposit thickness on the inside surfaces of natural gas cooler tubes is presented.
This method does not require opening and inspecting a cooler as it is based on the measurement of gas cooling degree, i.e.
the gas temperature difference between the cooler inlet and discharge. The deposit layer on the internal heat transfer surfaces
is of semi-liquid consistency and its thermal conductivity coefficient has not been investigated until now. This paper describes
the experimental determination of the deposit thermal conductivity coefficient. This parameter enables determination of a
cooler’s performance as a function of current deposit thickness. Practical application of the method is illustrated in the
case of CH_R cooler working in the KS01 compressor station in Vel’ké Kapušany, Slovakia. For this type of cooler, a diagram
for deposit thickness as a function of the gas cooling degree is presented. 相似文献
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冷凝露点法是一种高精度的食品水分活度检测方法,温度控制是其关键技术之一。本设计采用最新型Cortex-M0核芯LPC1114作为控制单元,选用半导体制冷器和加热器作为温度控制元件,运用数字PID智能算法进行温度控制。可用于水分活弗则量辅助实验精度高、响应陕,取得良好的控制效果。 相似文献
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废气再循环(EGR)冷却器的工作条件恶劣,经常由于热负荷过高而出现结构开裂问题,严重影响实际使用性能。针对某型EGR冷却器,采用流固耦合热分析方法,用计算流体力学和有限元软件计算分析了EGR冷却器的流场、温度场和热应力分布,其数值模拟结果与测试结果吻合;验证了EGR冷却器的开裂现象系工作时所受热应力过高导致。据此,通过在外表面增加扰流槽对EGR冷却器结构进行了一定的改进,试验结果表明,改进后的EGR冷却器不再出现开裂现象,研究结果表明流固耦合分析是解决EGR冷却器开裂问题的有效方法。 相似文献
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全面分析了液压系统在工作中发热现象的产生机理,冷却器的种类及使用原则,重点介绍液压系统中热平衡中系统发热量计算方法及加热器、冷却器的相关计算方法。 相似文献
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Measuring in-plane thermoelectric properties of submicron thin films has remained a challenging task. Here we report a method based on a suspended microdevice for four-probe measurements of the Seebeck coefficient, thermal conductivity, electrical conductivity, and thermoelectric figure of merit of patterned indium arsenide (InAs) nanofilms assembled on the microdevice. The contact thermal resistance and intrinsic thermal resistance of the 40 nm thick InAs nanofilm sample were measured by using the nanofilm itself as a differential thermocouple to determine the temperature drops at the contacts. The microdevice was also used to measure a 190 nm thick silicon dioxide (SiO(2)) film and the results were compared with those reported in the literature. A through-substrate hole under the suspended microdevice allows for transmission electron microscopy characterization of the nanofilm sample assembled on the device. This capability enables one to correlate the measured thermoelectric properties with the crystal structures of the nanofilm. 相似文献
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针对大功率光学器件和设备的热严重影响其稳定性、性能和使用寿命的问题,提出了一种基于能量回馈的智能高效热电散热系统。利用基于改进的增量式比例积分微分(PID)算法快速实现高精度温度控制,通过能量回收机制实现热电制冷器(TEC)制冷效率的提升。采用光伏充电为主、电源充电为辅的电源管理策略,通过上位机监测与控制实现对两组蓄电池的高效充放电切换。同时,利用Python+PyQt5为散热系统搭建可视化图形操作界面。研究表明,设计的实验系统实现了对TEC器件的电路信息监测与温度高效控制,可为解决大功率光学器件和系统的散热问题提供参考。 相似文献
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Seung-Woo Lee Han-Kil Yeom Hwa Ki Lee Kil-Jong Park 《International Journal of Precision Engineering and Manufacturing》2010,11(3):375-380
According to the development of machine tools to higher speed and multi axes, thermal error which is known to account for
about 70% of the total error of machine tools is becoming a serious issue. To reduce thermal error, the heat generating parts
of machine tools are cooled down by direct contact with a cooling medium. The medium in most cases is oil, thus, the cooling
device is called oil cooler. In this study, an oil cooler system employing hot gas bypass method was developed to improve
the performance including energy efficiency of the oil coolers used for ultra-precision machine tools. Through tests, the
developed system exhibited high temperature control accuracy of ±0.1°C, and less energy consumption than conventional on/off
type (equipped with heater for preventing excessive cooling) by about 45%. The proposed oil cooler system is applicable to
semiconductor process, ultra-precision injection molds, as well as ultra-precision machine tools to improve product quality
and energy efficiency of production facilities. 相似文献
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间接蒸发冷却器热工计算数学模型及验证 总被引:6,自引:1,他引:5
对几种间接蒸发冷却器的热工计算数学模型进行了简要介绍和对比,并对其中两种计算方法进行了实验验证,结果表明周孝清、陈沛霖提出的方法更适用于工程实践。 相似文献
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Thermally stimulated current (TSC) techniques have been applied to study thermally activated events in many materials. However, the temperature ramp rates in traditional TSC are typically too slow (few degrees per minute) to monitor materials whose properties are strongly time dependent. A fast ramp rate TSC (FR-TSC) technique was developed with ramp rates of 1-5 K/s. This is up to 100 times faster than traditional TSC, so that material changes can be appropriately quantified in the time scale at which they take place. In this paper, the experimental design and challenges to achieve fast and stable ramp rates and to measure the low-level currents are discussed. The fast ramps were attained using a thermoelectric cooler, controlled by a proportional-integral-derivative feedback loop, for both heating and cooling. FR-TSC measurements (1 K/s and 20-100 degrees C) on poly(vinylidene fluoride-trifluoroethylene) ferroelectric thin films are discussed as an example material. From these measurements, thermally activated currents as well as irreversible and reversible charge dynamics were readily distinguished with multiple thermal cycles. These measurements suggest that this technique holds substantial promise in quantifying charge dynamics in fast response materials. 相似文献
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Zoltán Pálmai László Csobod 《The International Journal of Advanced Manufacturing Technology》2017,88(1-4):115-126
It is a well-known fact that thermoelectric currents, reaching even the scale of ampere, develop during chip formation in the machine-workpiece-tool-chip. The impact of these currents on tool wear in end-milling was examined with a qualitative thermoelectric model, in which wear is described by an autonomous non-linear differential equation. Cutting temperature was measured by a so-called natural thermoelement with C60 and P35 carbide pair, which were submerged into heated Sn bath at validation. The mathematical model can be solved by a numerical method, where the inverse of the differential equation of wear was used. The wear curves determined by calculation fitted well with the measurement results. The results were achieved by cutting experiments using P35 carbide conducted on the C45 quality steel workpiece. It was found that the optimal solution with respect to the wear of the tool behaving as a natural thermal element might be achieved if the current is compensated by an external power source. Based on the model, anomalies might occur in some cases in the thermoelectric system. Further research is necessary to decide if this is only a special characteristic of the model or the model is interpreting really the actual processes. 相似文献