红外热像仪外场测温的大气透过率二次标定

为了实现测温红外热像仪的外场精确测温,研究了大气透过率的二次标定。建立了红外热像仪的外场远距离测温标定模型,采用一个标准面源黑体和红外热像仪对大气透过率进行了二次标定。首先,用标准面源黑体的设置温度标定大气透过率的二次修正系数;然后,在已知目标感兴趣区域发射率的情况下,用二次修正系数对未知辐射源测量值进行修正,实现未知辐射源目标辐射温度的准确测量。实验显示,随黑体设置温度从50℃不断升高(二次大气透过率近似为1),大气二次透过率修正系数在50～100℃内迅速下降,在100～200℃内下降趋势减缓,逐渐接近于约为0.7的常数。实验结果为测温红外热像仪外场精确测温提供了保证。     

星载多谱段双视场紫外大气探测仪

针对天底和临边综合紫外大气探测的需求,分析了天底和临边双视场观测原理和技术指标,设计和研制了多谱段双视场紫外大气探测仪原理样机。该样机光学系统由前透镜组、环形透镜、中继透镜组和窄带滤光片组成,3个工作谱段的中心波长分别为265nm、295nm和360nm,带宽均小于20nm,天底视场为10°,临边视场为360°(141.8°~146.6°),焦距为5mm,F数为3.3,通过切换窄带滤光片完成3个谱段的探测。多谱段双视场紫外大气探测仪整机质量约为3kg,体积为Φ90mm×300mm。对样机的静态传递函数和像面照度均匀性进行了测试。测试结果表明,在特征频率38.5lp/mm处,天底视场的静态传递函数为0.24,临边视场的静态传递函数为0.22,像面照度均匀性为94%,均优于设计指标要求。该原理样机体积小、重量轻,满足空间光学遥感仪器小型化和轻量化的要求。     

模糊控制在橡胶硫化温度控制中的应用

橡胶硫化温度控制是保证橡胶硫化正常进行的关键之一。由于模糊控制不必事先知迸被控温度严格的数学模型,可根据操作人员的经验,来制定模糊控制规则,采用计算机和模糊控制理论来实现ri动控制,可得到良好的控制效果。木文研究利用可编程序控制器(PLC)和简化的摸糊控制理论,通过脉宽调制(PWM)的方法来实现硫化温度的自动控制。在要求的硫化温度在200上5℃时,实际温度可以连续8小时以卜控制在 200土5℃、因此可以得到良好的硫化质敬。     

近室温样品加热炉温度的模糊PID控制研究

根据红外隐身材料光谱发射率测试方法的要求,提出了一种基于半导体制冷器的近室温样品加热炉系统。在对加热炉系统特性进行分析的基础上,建立了基于模糊PID控制的系统仿真模型。经仿真及实验可知,在加热和制冷条件下,实际温度与设定温度之间的误差分别为±0.20℃和±1.00℃。结果表明,系统稳定性好,响应时间短,解决了近室温样品加热炉抗干扰能力弱、不易控制等问题。     

刀具温度场的有限元分析

建立了正交切削的热传导分析模型,采用有限元法中的Lagrange法研究刀具的温度场,并分析刀具前角、进给量 对切削温度的影响规律,为研究刀具磨损机理、提高刀具寿命提供有用的参考数据。     

Thermal imaging study of temperature fields in shallow flows

Thermography has been used to investigate the scalar transport in shallow-water jet and wake flows. Warm water was injected uniformly over the depth into these flows, and the temperature variations at the water surface were captured by a thermal camera. The mixing of the warm water with the ambient fluid in shallow flows, as the result of turbulent diffusion and dispersion, was analysed. The development of the mean and fluctuating temperature along the flow was examined and compared with the past studies of scalar transport in shallow jets and wakes. The results agree well with the theoretical analyses and the previous measurements, where dye was used as the tracer. Through the detailed studies, it has been demonstrated that thermal imaging technique provides a new quantitative method for studying turbulent mixing phenomena in shallow waters. Compared with conventional scalar measurement techniques, the biggest merit of the thermal imaging method is that it involves a very simple experimental setup.     

Method of determining temperature fields in rubbing solid contacts

The aim of this study has been to develop a new method of recording temperature fields over friction surfaces and within thin surface layers of friction pair elements. In this, the materials tested include steel, titanium, aluminium, silica glass, and sapphire. When studying the temperature distribution in the surface layers of mated bodies a pin‐on‐disc geometry is used. The friction regimes are as follows: the sliding velocity is varied within the range 10–80 m/s and the nominal pressure is 0.06–0.5 MPa. Experiments have been performed using a set‐up involving an optoelectronic scanning technique and comprising a high‐speed friction machine and a temperature field recording system. The latter consists of an optoelectronic transducer, a monitor, a video tape recorder, an amplifier, a device to form oscillograms of image brightness, and a digital storage oscillograph.     

Reliability based optimal design of a helicopter considering annual variation of atmospheric temperature

This study presents the Reliability Based Design Optimization (RBDO) of a helicopter, used in order to guarantee target performances for a large variation of annual atmospheric temperatures. To this end, analytic methods — statistical and empirical equations of aerodynamics, structure, propulsion and so on — are synthetically coupled within the multidisciplinary design analysis tool of the conceptual helicopter. Additionally, an atmospheric temperature model for annual air temperature variation is constructed in bimodal shape by considering 10 years worth of day-averaged air temperature data provided by the Korea Meteorological Administration. Based on this analysis tool and the annual atmospheric temperature model, the RBDO of a helicopter is performed to minimize maximum takeoff gross weight, with the helicopter rotor configuration parameters as a design variable. A Monte-Carlo simulation is used to accurately evaluate the reliabilities of endurance and range. This RBDO strategy is applied to a 22,000lb class medium utility helicopter, and the results are compared with those of a deterministic design optimization (DO) using constant air temperature and baseline helicopter. Through comparison of the results obtained from RBDO and those from the deterministic design optimization, it can be confirmed that the optimal design of RBDO results in greater improvements in performance over the baseline, for a wide range of operating air temperatures, than baseline helicopter and optimal shape of DO using constant air temperature. Therefore, in designing a helicopter to be operated in temperate climatic regions that show large variation in air temperature, such as Korea, China, the U.S.A, and so on, it is important to perform RBDO with reasonable annual air temperature models constructed from well-known and reliable data.     

Effect of temperature fields on wear of nonmetallic materials at abrasive machining

Wear characteristics of silicate glass and sapphire at abrasive machining have been studied. The data obtained and the analysis of images of worn surfaces have allowed the authors to conclude that two modes of material damage run simultaneously; these are the local melting of the glass followed by its squeezing towards the contact exit and periodical fatigue fracture (growth of microcracks). Under a short-term effect of high thermal stresses the glass was found to undergo thermal cracking even outside the contact site. The crystalline material (sapphire) demonstrated anisotropy of fatigue strength under abrasive wear, when its wear rate in two perpendicular directions differed almost by an order of magnitude. The possibility of sapphire damage outside the contact site is explained by the position of the maximal surface temperature region being some distance ahead of the zone of the abrasive tool-blank contact.     

金属非稳定热成型三维温度场的有限元模拟

以型腔模铸造和热锻造拔长问题为例，阐述传热有限元在复杂的三维非稳定热成型模拟计算中的应用方法。采用空间单元划分和时间轴差分的方法，递推计算出瞬态温度场数值解。铸造冷凝问题以当量温度来控制结晶时的温度下降过程并反映液固转变的程度；锻造拔长问题则进行温度场和变形力能的交替遗传计算来模拟变形与传热之间的互相影响。     

Solution of temperature fields in hydrodynamics bearings by the numerical network method

Solution to the 2-D steady-state nonlinear heat conduction equation, involving cylindrical coordinates, applied to a plain bearing by a simple and versatile numerical technique based on network method is presented in this work. These advantages of the technique are necessary for the status evaluation of industrial machines during operation because time and computing resources are limited. The pressure field in the fluid is previously solved from the Reynolds equation by finite element method. The main difficulty is associated with the exponential dependency of the viscosity on temperature. The proposed model is very efficient and requires negligible computing times. Solutions are very close to the experimental and numerical results of other researchers.     

Rough-cut fast numerical investigation of temperature fields in selective laser sintering/melting

The surface micro/nano-topographical modifications have been widely used in improving the biocompatibility of biomedical implants. In this paper, the feasibility of the micro-milling process for construction of micro-grooves without burrs on titanium alloy materials was investigated. Low melting point alloy was selected as supporting material to extend the boundary of the workpiece, so the burrs produced on the surface of supporting material. A novel hierarchical micro/nano-topography with micro-grooves and TiO₂ nanotubes was fabricated on titanium alloy surface combining micro-milling and anodic oxidation. The scanning electron microscope, energy-dispersive spectroscopy, laser scanning microscope, and contact angle tester were used in characterizing surface features of machined workpieces. Results showed that the micro-grooves with dimension of 40 μm in depth were machined using V-shaped cutting tool, and the TiO₂ nanotubes with dimension of 70 nm in diameter were superimposed on the surfaces of micro-grooves by anodic oxidation. In addition, the hydrophilicity of micro/nano-structured surface was significantly enhanced with the water contact angle decreasing from 114.8° to 60.3°. It is concluded that this hybrid method combining micro-milling technology and anodic oxidation can be used in improving the biological activity of biomedical implants through changing surface topographies.     

基于有限元分析钢板焊接温度场的影响因素

利用ANSYS软件的APDL语言以及单元"死活"技术模拟焊接的填充过程,较好的模拟焊接加热过程及整个温度场的瞬态变化并实现了参数化编程;利用有限元分析软件ANSYS对钢板焊接温度场进行动态模拟,建立高斯函数热源模型,对各项焊接参数的合理选择和优化提供有效的参考.     

YSZ atmospheric plasma coating method for improved high temperature corrosion and wear resistance

Journal of Mechanical Science and Technology - The yttria stabilized zirconia (YSZ) ceramic coating of feed rollers exposed to the high temperature environment used in the floating process for...     

高速切削温度场的三维有限元模拟

基于高速切削实际工艺分析,通过合理设置边界条件,建立高速切削下工件-刀具相互作用的三维数值模型,采用有限元法模拟了使用涂层刀具高速切削45钢时的温度场分布状况,并比较不同的切削速度、不同的刀-屑界面摩擦因数下刀具的温度场分布,模拟结果与试验结果具有较好的一致性.     

机抖激光陀螺温度场的有限元模拟与实验

为了研究机抖激光陀螺内在热源对陀螺性能的影响,利用有限元分析软件ANSYS建立了机抖激光陀螺的温度场模型,对有限元模型进行了温度场仿真分析。描述了有限元模型的简化方法,介绍了材料热参数的处理及热生成率和换热系数的计算方法,最后给出了机抖激光陀螺的稳态温度场1h和3h的瞬态温度场分布,指出了机抖激光陀螺的最高、最低温度分布区域及温度梯度分布情况。设计了高精度的铂电阻测温电路,其测温精度为0.005℃,仿真与实验对比结果表明,计算误差优于2%,验证了模型的正确性和合理性。本文的研究方法可为陀螺盒体内部测温点的选取提供指导意见,有助于提高机抖激光陀螺的温度补偿效果。     

复合光物理治疗仪体表温度模糊控制系统

本文首先介绍了复合光物理治疗仪的硬件组成原理,然后针对人体这一复杂的特大系统,应用Matlab模糊逻辑工具箱设计了以人体体表温度为被控对象的一种模糊控制方案.通过对被控对象的参数或结构发生变化时的仿真分析,得出该模糊控制器能够保持响应的快速性以及无静差、无超调的优良性能,具有很好的鲁棒性和适应性.     

Numerical solution for temperature and flow fields in crossflow moving bed heat exchanger

The steady state solution of flow and temperature distributions in the crossflow moving bed heat exchanger using granular materials was obtained numerically. The effectiveness of crossflow moving bed was compared with that of crossflow heat exchanger with both fluids unmixed. The effect of bed geometry and solid particle size on the performance of moving bed was investigated. Also, the effect of thermal capacities of gas and solid particle and the gas flowrate was studied. The design data to estimate the heat exchanger performance of moving bed are given from the results of calculation in this study.     

基于MCGS的3500吨液压机模糊温度控制

针对3500吨液压机的温度大滞后特性．本文在MCGS点数有限的情况下，设计了一种以实测温度变化方向为判断条件的单输入单输出Sugeno简易模糊温度控制系统。实际生产表明，该系统具有动态响应快、超调小、抗干扰和负载能力俱佳的优点．达到了电极产品生产工艺要求．大大提高了产品合格率及产品质量。     

松弛热定型机腔内三维流场及温度场数值模拟研究

针对松弛热定型机腔内温度场均匀分布控制问题,利用计算流体力学(Computationalfluid dynamics,CFD)方法对腔内流场及温度场进行数值模拟。通过腔内气固耦合传热分析,研究了采用三种不同开孔率均风网时,热定型机腔内的流场及温度场的分布情况。通过分析认为5%开孔率时腔内温度均匀性较好,同时随着开孔率的增大,有利于降低结构应力集中,保证定型机结构寿命,为松弛热定型机的结构改进设计及改善定型效果提供依据。