弥散介质条件下辐射测温方法（特邀）

在航空航天、冶金铸造等各种工业现场高温热试验过程中,需要在高浓度弥散介质遮蔽物件表面的条件下,快速、准确地获取试验件表面的高温温度。传统的辐射测温方法包括波段辐射法、亮度法、比色测温法、多波长测温法等,是实现高温测量的一种主要测量方法。弥散介质由于介质粒子的作用会产生各种光谱散射、吸收和发射效应,给高温的准确测量带来了很大的干扰,导致测量结果产生偏差,必须要改进经典辐射测温方法。论述了弥散介质条件下几种主要的辐射测温方法,包括试验数据反推法、热辐射计算法、多通道分裂窗法、信息复原计算法、神经网络计算法等,分析了各种方法的优点和不足,总结了弥散介质条件下辐射测温方法面临的挑战和发展趋势。     

基于自适应模糊PID算法的窑筒体红外测温与制冷的精确控制

工业温度控制系统的非线性、时变性和滞后性等特性常严重影响温度控制的快速性和准确性,这会给实际生产等带来巨大的危险隐患。本文将探讨对基于红外测温的窑筒体如何实现精确测温以及如何利用自适应模糊PID算法进行相应控制的情况,并通过Matlab仿真展示部分成果。结果表明,该类算法在窑筒体红外测温制冷中对于提高系统性能起到关键性作用.     

A New Sidelobe Correction Algorithm for Microwave Radiometers: Application to the Envisat Instrument

The antenna temperature measured by a microwave radiometer is converted in brightness temperature (TB) by removing the different contributions that do not come from the main lobe of the antenna. Among them, the Earth contribution in the sidelobes may be significant as for the Environmental Satellite mission due to the antenna position on the platform. In such a case, simple corrections commonly applied on previous altimetry missions are inadequate, and a more accurate correction should be determined. We propose in this paper a new method based on global seasonal tables of contamination. This allows application of an accurate sidelobe correction in space and time in the retrieved TB computation     

FDTD electromagnetic and thermal analysis of interstitialhyperthermic applicators

The electromagnetic and thermal behavior of interstitial applicators was analyzed by using the finite-difference time-domain method. Two configurations were considered: a simple insulated dipole antenna radiating in a layered tissue, and an air cooled applicator radiating in a tissue-equivalent phantom. The proposed approach allows a detailed modeling of the complete structure of the applicator. Furthermore, specific absorption rate and temperature distributions can be determined considering real clinical or experimental conditions. The temperature distribution for the air cooled applicator has been compared with experimental results     

空间分辨率对半导体器件光学测温结果的影响

从空间分辨率的定义出发,指出物镜的数值孔径和光的波长是决定光学仪器空间分辨率的主要因素。给出了空间分辨率影响半导体器件结温检测结果准确度的原理。对GaN HEMT进行了不同空间分辨率下的显微红外温度检测,较低空间分辨率下的测温结果低于高空间分辨率下的测温结果,证明空间分辨率的不足会导致温度测量结果偏低。     

基于TDLAS技术气体浓度测量的温度修正方法

精确检测气体浓度在大气环境保护、工业生产控制、废气排放监测等领域有着迫切需求。可调谐二极管激光吸收光谱技术(TDLAS)是实现气体浓度精确检测的重要方法,然而温度变化却为浓度精确测量带来较大误差,因而对检测结果进行温度修正是十分必要的。本文从理论角度出发,阐述了TDLAS技术检测气体浓度的温度影响机理,重点分析并归纳了基于TDLAS技术的气体浓度测量的温度影响修正方法,并展望了其发展趋势。     

城市典型植被的热辐射特性研究

植被在改良土壤、防风固沙、净化环境、调节气候以及人类生存等方面具有不可替代的重要作用,因此植被研究是地球生态环境研究中不可或缺的内容。而日趋成熟的热红外监测技术则为植被研究提供了一种更快捷、更有效的手段。通过对吉林省长春市典型地面植被的亮度温度进行测量,得到了不同类型植被的热辐射特性。研究了不同角度、不同波段、不同时相和不同类型植被的热辐射特性。结果表明,植被类型对植被的亮度温度影响较大,波段对植被的亮度温度影响较小,测量时间对植被的亮度温度影响明显,探测角度对植被的亮度温度影响较大。该实验为植被类型的进一步精确识别和分类提供了重要依据。     

Automatic Contrast Enhancement by Transfer Function Modification

In this study, we propose an automatic contrast enhancement method based on transfer function modification (TFM) by histogram equalization. Previous histogram‐based global contrast enhancement techniques employ histogram modification, whereas we propose a direct TFM technique that considers the mean brightness of an image during contrast enhancement. The mean point shifting method using a transfer function is proposed to preserve the mean brightness of an image. In addition, the linearization of transfer function technique, which has a histogram flattening effect, is designed to reduce visual artifacts. An attenuation factor is automatically determined using the maximum value of the probability density function in an image to control its rate of contrast. A new quantitative measurement method called sparsity of a histogram is proposed to obtain a better objective comparison relative to previous global contrast enhancement methods. According to our experimental results, we demonstrated the performance of our proposed method based on generalized measures and the newly proposed measurement.     

A clinical water-coated antenna applicator for MR-controlled deep-body hyperthermia: a comparison of calculated and measured 3-D temperature data sets

A magnetic resonance (MR)-compatible three-dimensional (3-D) hyperthermia applicator was developed and evaluated in the magnetic resonance (MR) tomograph Siemens MAGNETOM Symphony 1.5 T. Radiating elements of this applicator are 12 so-called water coated antenna (WACOA) modules, which are designed as specially shaped and adjustable dipole structures in hermetically closed cassettes that are filled by deionized water. The WACOA modules are arranged in the applicator frame in two transversal antenna subarrays, six antennas per subarray. As a standard load for the applicator an inhomogeneous phantom was fabricated. Details of applicator's realization are presented and a 3-D comparison of calculated and measured temperature data sets is made. A fair agreement is achieved that demonstrates the numerically supported applicator's ability of phase-defined 3-D pattern steering. Further refinement of numerical models and measuring methods is necessary. The applicator's design and the E-field calculations were performed using the finite-difference time-domain (FDTD) method. The calculation and optimization of temperature patterns was obtained using the finite element method (FEM). For MR temperature measurements the proton resonance frequency (PRF) method was used.     

Multifrequency radiometric determination of temperature profiles ina lossy homogeneous phantom using a dual-mode antenna with integralwater bolus

In the treatment of cancer, microwave hyperthermia has been established as an efficient adjunctive procedure to radiation therapy and chemotherapy. Wider acceptance of this method awaits schemes to measure volumetric temperatures noninvasively in human tissue for control of the heating process. This effort describes the design and performance of a new microstrip applicator intended for homogeneous heating of superficial tissue while at the same time monitoring temperature of the underlying tissue by noninvasive radiometric sensing of black-body radiation from the heated volume. Radiometric capabilities are assessed in terms of accuracy of up to six measured brightness temperatures applied in an inversion algorithm from which one-dimensional depth temperature profiles are generated. Based on radiometric signals recorded over the 1-4-GHz range, the temperature accuracy determined from statistical analysis of 200 realizations of the process is better than ±0.2°C to a depth of 5 cm in phantom. Aperture heating uniformity is assessed with electric field scans in a homogeneous muscle phantom. As long as sufficiently thin (< 5 mm) water boli are used, SAR distributions at 1-cm depth in phantom extends effectively just outside the aperture perimeter, making this microstrip antenna an excellent building block element of larger multi-antenna array applicators     

Evaluation of a Therapeutic Direct-Contact 915-MHz Microwave Applicator for Effective Deep-Tissue Heating in Humans

A 13-cm square direct-contact microwave applicator which operates at 915 MHz was evaluated in tissue models and human volunteers to determine its therapeutic effectiveness. It was found that the applicator with radome- and forced-air cooling selectively elevates temperatures in muscles (1-2 cm) to 43-45/spl deg/C. At this higher range of temperature, certain physiologic responses such as an increase in blood flow are produced. The applicator may also be used to heat malignant tumors of muscle.     

Two-load radiometer precision and accuracy

The advent of fast computers and digital signal processing permits many aspects of radiometer operation to be decided in real time so that precision and accuracy are maximized. Closed-form expressions for precision, optimal antenna/load dwell times, and maximum chopping period are derived for a class of radiometers that uses two loads to calibrate its measurements of antenna brightness temperature. The importance of load brightness temperature selection emphasizes the need to develop "cold" calibration loads that can operate at ambient temperature. A method of incorporating critical thermistor data into the radiometer brightness temperature calibration can be used to help stabilize measurements against drift and may permit radiometers to operate without thermal control in some low-accuracy applications.     

Automatic temperature controller for multielement array hyperthermia systems

This paper concerns the optimization and performance analysis of an automatic control algorithm for managing power output of large multielement array hyperthermia applicators. Simulation and corresponding measurement of controller performance in a solid tissue equivalent phantom model is utilized for analysis of controller response to dynamically varying thermal load conditions that simulate clinical treatments. The analysis leads to an optimum controller which demonstrates the ability to achieve a uniform and stable temperature profile over a large surface area regardless of surrounding thermal load. This paper presents several advancements to the performance of a previously published control routine, including: 1) simplified simulation techniques for thorough characterization of controller performance; 2) an optimization procedure leading to an improved hybrid control algorithm for maintaining optimal performance during periods of both "rising" and "steady-state" temperature; 3) performance analysis of a control algorithm tailored for large area hyperthermia treatments with a mulitelement array applicator. The optimized hybrid controller is applied to the conformal microwave array (CMA) hyperthermia system previously developed for heating large area surface disease such as diffuse chestwall recurrence of breast carcinoma, and shown to produce stable, uniform temperatures under the multielement array applicator for all thermal load conditions.     

基于亮温光谱的表面沾染物探测方法

针对表面沾染探测中存在的不足,提出亮温光谱法。通过高灵敏度红外遥测光谱仪非接触探测获得沾染物的辐亮度光谱,利用光源和沾染本底的高发射率特性,通过普朗克公式转换得到亮温光谱,直接获得沾染物特征信息。无需预测沾染本底,特别适合已中毒事故现场。首先讨论该方法的探测原理,然后分别使用亮温光谱法和背景扣除法对铝板表面的沾染物二甲基硅油(Poly(dimethylsiloxane),PDMS)和磷酸三乙酯(Triethyl phosphate,TEP)进行探测。结果表明,亮温光谱法提取出的沾染物的特征与背景扣除法的相同,可准确识别沾染物类型,同时避免了背景扣除法对背景光谱的依赖。该方法简单可靠,测试迅速,有很大的应用潜力。     

A Direct-Contact Microwave Lens Applicator with a Microcomputer-Controlled Heating System for Local Hyperthermia

A direct-contact lens applicator for local microwave hyperthermia is proposed and developed with a computer-controlled microwave heating system. The applicator is a practical one that can converge the radiated electromagnetic field to deposit its energy deep in human tissues. The experimental results, which agree well with the theoretical ones, show that the applicator which operated at 2450 MHz could heat at twice the depth at which a simple and conventional waveguide applicator could heat. The experimental results using a developed computer system that supplies microwave energy and circulated cooling water to the developed applicator show that the fluctuations of temperature at the heating location in the human tissue model were maintained within +-0.3° C of the set temperature. The results of the phantom model and the animal experiment using the system with the applicator show that the maximum depth of noninvasive heating was more than 30 mm below the surface. These results are available for the clinical hyperthermia treatment of cancer.     

A Hot Calibration Load of Measuring and Controlling Temperature

A hot calibration load whose temperature is measured and controlled is described, and the measurement method of the microwave absorber reflectivity is also mentioned. In the end, two mathematical models are provided. The numerical results show obviously that the brightness temperature is the function of the angle of view, the contribution of the insulation layer can not be neglected.     

Radiometric Calibration of LIDAR Intensity With Commercially Available Reference Targets

We present a new approach for radiometric calibration of light detection and ranging (LIDAR) intensity data and demonstrate an application of this method to natural targets. The method is based on 1) using commercially available sand and gravel as reference targets and 2) the calibration of these reference targets in the laboratory conditions to know their backscatter properties. We have investigated the target properties crucial for accurate and consistent reflectance calibration and present a set of ideal targets easily available for calibration purposes. The first results from LIDAR-based brightness measurement of grass and sand show that the gravel-based calibration approach works in practice, is cost effective, and produces statistically meaningful results: Comparison of results from two separate airborne laser scanning campaigns shows that the relative calibration produces repeatable reflectance values.      

综合孔径辐射计亮温反演算法研究

综合孔径辐射计通过干涉测量技术反演目标辐射亮温图像,属于空域傅里叶变换范畴,其中相关运算中由各阵元之间传输延时造成的空间解相关效应,对亮温反演结果具有重要影响.文章从空域频率采样的角度分析了反演算法,同时探讨了 G 矩阵相关性以及空间解相关效应对亮温反演的影响.在传统的BG（Backus-Gilbert）算法基础上,提出了补偿空间解相关效应的方法,利用去相关矩阵对带宽、通道不一致性造成的误差进行了补偿.     

A broadband microwave radiometer technique at X-band for rain and drop size distribution estimation

Radiometric brightness temperatures below about 12 GHz provide accurate estimates of path attenuation through precipitation and cloud water. Multiple brightness temperature measurements at X-band frequencies can be used to estimate rainfall rate and parameters of the drop size distribution once correction for cloud water attenuation is made. Employing a stratiform storm model, calculations of the brightness temperatures at 9.5, 10, and 12 GHz are used to simulate estimates of path-averaged median mass diameter, number concentration, and rainfall rate. The results indicate that reasonably accurate estimates of rainfall rate and information on the drop size distribution can be derived over ocean under low to moderate wind speed conditions.     

双色热敏磷光涂层测温技术

空气动力表面温度和压力分布的精确测量对理解复杂流场内部机制和流体力学仿真模型的验证具有重要意义。热敏磷光表面测温技术作为一种面测量技术,具有非接触测量、可对试件全尺度测量、空间分辨率高等优点。开发了一种室温到800 K 温度范围内的双色热敏磷光涂层材料。该发光材料受激辐射的发光光谱的两个发射峰光强在不同温度下呈现不同的衰减趋势,根据这种规律发展了双色测温技术。建立了热敏涂料温度标定系统,获得了双峰光强比与温度的变化曲线。采用双色法测温技术测量了旋转曲面物体表面的温度分布。结果表明,双色热敏磷光涂层测温技术能够实现物体表面温度的定量测量,对于测试技术的发展具有重要推动作用。