空间光学遥感器的热设计实例及其仿真分析

针对结构非对称、载荷非对称以及约束非对称的空间光学遥感器进行了热设计,应用热分析软件对其进行了计算机仿真.分析了空间光学遥感器各个方向到达的平均外热流,并根据其工作模式与热控制要求,遵循"被动热控为主,主动热控为辅"的热控制策略,对空间光学遥感器进行了热设计.根据采用的热控措施,对热控系统进行了仿真分析,得到了满意的?哪 结果,验证了热设计的正确性.该研究方法对各类空间光学遥感器的热分析和热设计有一定的指导和借鉴作用.     

Influence of temperature profiles on thermal tactile sensation

The theoretical and experimental study of a thermal model describing the thermal response of skin when a finger contacts with materials are presented in the paper. Few studies have considered the influence of finger skin’s thickness on the thermal sensation. Therefore, the theoretical solution of the temperature change at thermoreceptors that function as thermal sensors during contact is given out. Also a principle model for reproducing thermal cues is proposed. When a thermal tactile display simulates a sensation of thermal presence, due to inter-individual variations, it is difficult to set the initial skin temperatures to a specific value. The concept of relative thermal recognizing profile is proposed and applied to deal with it, by which the skin initial temperature is measured instead of being set in simulating. The initial temperatures are measured at the beginning and then the corresponding temperature profiles are obtained to simulate the thermal cues of tactile sensation. The experimental results of material recognition were presented.     

High-quality as-is 3D thermal modeling in MEP systems using a deep convolutional network

With the growing need for automated condition monitoring and analysis in existing buildings, significant effort has been spent on the development of three-dimensional (3D) thermal models. However, little attention has been paid to ensuring the quality of these 3D thermal models, which can directly impact the accuracy of condition monitoring and analysis results. This study aims to propose a method to generate a high-quality 3D thermal model for mechanical, electrical, and plumbing (MEP) systems by bridging the quality discrepancy between high-resolution laser scan data and low-resolution thermal images using a deep convolutional neural network. The proposed method consists of two main parts: (1) improving the resolution of thermal images based on a deep convolutional network and (2) generating a high-quality 3D thermal model by mapping improved thermal images. The performance of the thermal image resolution improvement was validated using a dataset consisting of 312 thermal images. The results demonstrated that the quality of the improved thermal images based on a deep convolutional network was higher than conventional bicubic interpolation in terms of root mean square error (RMSE), peak signal-to-noise ratio (PSNR), and structural similarity (SSIM). Qualitative analysis of a 3D thermal model utilizing the resolution-improved thermal images was also conducted. This was further qualitatively analyzed to have resulted in improved overall quality of the 3D thermal model. The ability to generate a high-quality 3D thermal model can help auditors to perform automated condition monitoring and analysis in buildings based on objective and accurate data.     

Waterways structural optimum design of electric car radiator

Thermal resistance was composed by thermal resistance of Aluminum substrate,thermal resistance of convective heat transfer and the thermal resistance of the cooling liquid.The change rule was studied through the calculation on Aluminum plate thermal resistance,thermal resistance of convective heat transfer and the thermal resistance of the cooling liquid.Its change regularity was simulated by toolbox In the MATLAB,and it was found that thermal resistance of convective heat transfer effect on the efficiency was most obvious in a certain amount of the heat and flow for thermal resistance of the Pin-fin radiator under the premise.The structural parameters of radiator were related to the size of thermal resistance.     

An efficient thermal actuator design for the thermal flying height control slider

In this work, we propose a novel thermal actuator by designing a thermal insulator, a thermal conductor, and their combination to the traditional thermal heater. The thermal-structure simulation coupled with air bearing simulation is used to simulate the actuation by the thermal actuator, as well as the effects on flying performance of slider being actuated. The simulation results show that an additional 0.8–1.1 nm flying height reduction can be obtained by applying the proposed thermal actuator when the flying height of TFC slider is about several nanometers.     

Passive infrared thermographic imaging for mobile robot object identification

The usefulness of thermal infrared imaging as a mobile robot sensing modality is explored, and a set of thermal–physical features used to characterize passive thermal objects in outdoor environments is described. Objects that extend laterally beyond the thermal camera's field of view, such as brick walls, hedges, picket fences, and wood walls, as well as compact objects that are laterally within the thermal camera's field of view, such as metal poles and tree trunks, are considered. Classification of passive thermal objects is a subtle process because they are not a source for their own emission of thermal energy. A detailed analysis is included of the acquisition and preprocessing of thermal images, as well as the generation and selection of thermal–physical features from these objects within thermal images. Classification performance using these features is discussed, as a precursor to the design of a physics‐based model to automatically classify these objects. Published 2009 Wiley Periodicals, Inc. *

1 This article is a US Government work and, as such, is in the public domain of the United States of America.

     

基于模糊控制的单片机式热保护器

针对电动机运行过程中因为绕组温度过高而影响绝缘性能的问题,设计了一种新型的基于模糊控制的单片机热保护器。通过分析和讨论各种标准和热过载模型,提出了最佳的可供单片机热保护器使用的热特性模型,即双时间常数的指数发热和冷却模型及其建模机理。针对电动机热保护器的延迟动作时间选取不准确的问题,利用模糊控制理论设计了热保护器的软件,提高了电动机热保护器的动作精度和可靠性。     

大型桁架展开机构热控涂层设计和热变形分析

为控制大型桁架展开机构在低地轨道(Low Earth Orbit,LEO)上的热变形,建立相应的热分析有限元模型,提出3种热控涂层备选方案.根据不同方案计算出机构在LEO上运行4个周期的瞬态温度场,并以最后一个周期的瞬态温度场为基础计算机构的热变形.对热变形的结果进行比较,选取变形值最小的热控涂层方案进行优化,使3根主梁的温差达到最小,从而有效控制桁架展开机构的热变形.     

Advanced thermal inertia modelling

This paper presents a simple and operational thermal inertia model by using the phase angle information of the diurnal temperature change. The model which is developed in this paper is based on our first-order approximation operational thermal inertia model. We use a second-order approximation for the boundary conditions and a second-order approximation for the surface temperature series expression. The importance of this work is that from our model real thermal inertia (as distinct from apparent thermal inertia) can be computed directly. The model requires only one field measurement parameter for the calculation of real thermal inertia; this is the time of maximum temperature in the daytime and this parameter is easily obtained from a meteorological station. For the regions having vegetative cover, the thermal inertia value is the weighted thermal inertia values of vegetated cover and soil ground.     

基于FEMAG-CZ热场仿真软件的单晶炉热场分析

基于FEMAGSoft公司的EMAG-CZ热场仿真软件具有模拟提拉法生长单晶体的热场仿真功能,提出使用温度梯度分析热场,通过仿真证明热场设计合理,满足生长单晶棒的要求。     

宽温区工作压力传感器热力学研究

介绍了硅-蓝宝石压力传感器的钛合金-蓝宝石复合弹性膜片在宽温区工作时温度变化材料不匹配引起的结构热应力,对弹性膜片的受热情况进行了分析,对不同结构形式传感器热稳定性影响程度进行了对比,利用P型掺杂硅温度特性减少结构热应力影响、降低传感器的热零点漂移.通过膜片结构选择和设计、材料选择、工艺优化和控制等可以使硅-蓝宝石压力传感器在-55~350℃宽温度范围内工作时热漂移不大于0.015%FS/℃,提高了宽温区工作时传感器的热稳定性.     

Exploring the addition of Landsat 8 thermal band in land-cover mapping

One focus of remote-sensing studies is obtaining highly accurate land-cover maps, which is essential for quantifying and monitoring changes in the environment. However, thermal data, which can provide auxiliary information, is often ignored in land-cover classification. In this study we compare the performance of different remote-sensing feature combinations with and without the Landsat 8 thermal band (band 10). The results show that overall the thermal feature had a positive effect on mapping land cover. A combination of spectral features, indices and the thermal feature maximized the improvement in accuracy. The proposed classifier was applied to map land cover in an area in Egypt. The thermal feature significantly reduced the confusion between cropland and wetland. The improvement in accuracy obtained by adding the thermal feature was analysed in a time series spanning 1 year. We found that the thermal feature improved the classification accuracy when temperature variations occurred among the different land-cover types. The effect of the thermal feature was also influenced by the land cover; in cloudless conditions, warmer weather can enhance the accuracy improvement of the thermal feature.     

真空热试验温度参考点热响应测试系统设计与实现

在航天器真空热试验的温度测量中应用最广泛的是热电偶测温系统,温度参考点是热电偶测温系统的重要组成部分,对温度测试数据的准确性和航天器产品的安全有很大影响。为了在热试验开机前对参考点铂电阻与热点偶补偿端匹配关系的正确性进行验证,设计了一种可用于真空热试验的热电偶测温参考点热响应测试系统。该系统由加热器以及控制箱组成,可通过LAN网络与上位控制计算机连接实现热响应远程测试。文章通过对参考点装置的热分析以及热响应测试原理分析,给出了系统的硬件结构以及软件设计方案,并在多项航天器真空热试验中投入使用,提高了航天器真空热试验热电偶测温系统的可靠性。     

Head-positioning control system using thermal actuator in hard disk drives

In this paper, we propose a head-positioning control system with a thermal actuator in hard disk drives (HDDs). The frequency response of the thermal actuator showed that the thermal actuator system has no mechanical resonant mode. Therefore, this head-positioning system with a thermal actuator can control the head-position beyond the major mechanical resonances caused by a voice coil motor (VCM) or suspensions. In this study, the system was a dual-stage actuator system; the first actuator was a VCM, and the second was a thermal actuator. Simulation results for a track-following control in an HDD demonstrated the validity of the proposed method.     

Numerical studies on the microclimate around a sleeping person and the related thermal neutrality issues

This article reports on two numerical studies on the microclimate around, and the thermal neutrality of, a sleeping person in a space installed with a displacement ventilation system. The development of a sleeping computational thermal manikin (SCTM) placed in a space air-conditioned by a displacement ventilation system is first described. This is followed by reporting the results of the first numerical study on the microclimate around the SCTM, including air temperature and velocity distributions and the heat transfer characteristics. Then the outcomes of the other numerical study on the thermal neutrality of a sleeping person are presented, including the thermal neutrality for a naked sleeping person and the effects of the total insulation value of a bedding system on the thermal neutrality of a sleeping person. STATEMENT OF RELEVANCE: The thermal environment would greatly affect the sleep quality of human beings. Through developing a SCTM, the microclimate around a sleeping person has been numerically studied. The thermal neutral environment may then be predicted and contributions to improved sleep quality may be made.     

Combining thermal inertia and a diurnal temperature difference cycle model to estimate thermal inertia from MSG-SEVIRI data

Thermal inertia is an important parameter in geological and agricultural applications. In this study, we present a method that combines models of thermal inertia and the diurnal temperature difference cycle to estimate the thermal inertia from Meteosat Second Generation Spinning Enhanced Visible and Infrared Imager (MSG-SEVIRI) data. This method can directly derive thermal inertia from MSG-SEVIRI brightness temperatures without the need to include the land surface temperature and emissivity. Two important parameters (the time of the maximum temperature and the diurnal temperature difference) that were input into the thermal inertia model were obtained by fitting the diurnal temperature difference cycle model to the diurnal cycle of land surface temperatures. The spatial distribution of thermal inertia shows that high thermal inertia values occur over vegetated areas, whereas low thermal inertia values occur over bare areas. The uncertainty in thermal inertia is investigated in terms of the uncertainties in the surface albedo, the time of the maximum temperature, and the diurnal temperature difference. The results indicate that the uncertainty in thermal inertia over vegetated areas is greater than that over bare areas. The consistency of the thermal inertia model is evaluated by analysing the difference in thermal inertia values on two consecutive days. The root mean square error of the thermal inertia differences under nearly identical surface and atmospheric conditions on two consecutive days is considered to be the error of the thermal inertia model.     

温度触觉传感器的材质识别仿真研究

采用温度触觉传感器对材质进行识别研究,介绍了一种基于热传导原理的材质识别方法,利用ANSYS软件对温度触觉传感器在不同温度差、不同基板材料和不同被测物体材料不同情形下的热传导进行了仿真实验。仿真结果表明:温度触觉传感器可用于识别吸热系数偏低的材料,接触温度可作为材质识别的一个重要判据。     

Evaluation of thermal energy storage and recovery for an electrical energy mediator system

Energy storage both electrical and thermal is a rapidly emerging field of interest toward the development of more sustainable energy systems. The inherent inefficiencies associate with electrical storage can be partially overcome when thermal storage that collects and storage the waste thermal energy for alternative uses is integrated. Consequently, thermal energy storage systems are an enabling technology that will allow increased energy efficiency of a community, permit load levelling to reduce peak electricity demand. In order to facilitate a technology evaluation, a sizing strategy is developed for a phase change material (PCM) thermal storage system that determines system requirements under given thermal energy capture and recovery cycles. The sizing process utilizes a simplified one-dimensional heat transfer model that estimates melt times for a phase change material thickness without detailed geometry information. This melt time estimate allows the proportion of phase change material to fluid routing materials to be calculated, giving an estimate of material cost for the thermal storage cell to determine economic feasibility. The model is compared to both experimental data and computational fluid dynamics models in order to determine its limitations. Through a specific example of hydrogen based distributed electrical energy mediator system, the utility of the sizing model in determining the estimated cost of thermal energy storage is demonstrated.     

A system-level model for a silicon thermal flow sensor

A system-level model with lumped parameters for a thermal flow sensor is presented. The model is built with 13 circuit cells consisting of thermal resistors and thermal capacitors in SPICE. The circuit cell originates from the heat conduction equation using the Finite Differential Method, including the 2-D thermal conduction cell, the convection cell, and the thermal capacity in the chip. Based on the thermal model of the flow sensor, the 2-D temperature distribution of the chip can be calculated with SPICE in both the constant power mode (CP) and constant temperature difference mode (CTD). As an example, the system level model of the thermal anemometer in the CTD mode was established in PSPICE. Wind tunnel test was carried out to verify the system model, and show a reasonable agreement with the simulation results, with an error less than 8%.