A Noninvasive Resonance-Based Method for Moisture Content Evaluation Through Microstrip Antennas

Several techniques for measuring the moisture levels of materials, particularly in the soil science area, are available. Nevertheless, the state of the art is rather lacking in moisture-sensing methods that are both inexpensive and noninvasive. The time-domain reflectometry (TDR)-based method, despite being a well-established low-cost technique for sensing moisture content, is intrinsically invasive due to the configuration of the probes that are commonly used. These considerations motivated the authors to investigate the adoption of simple inexpensive microstrip antennas as sensing elements for TDR-based moisture content measurements. For this purpose, the water content of the monitored material is sensed through the changes in the reflection scattering parameter S ₁₁(f) of the antenna. In particular, the change in the resonant frequency of the antenna, which is evaluated through an appropriate processing of the TDR waveforms, is correlated with the water content of the material under investigation. The ultimate goal is to assess a sensing method that can be implemented for inexpensive real-time noninvasive monitoring applications.     

一种利用S参数测量平衡RFID标签天线阻抗的优化方法

针对测量平衡RFID标签天线阻抗的准确性问题,提出了一种利用s参数测量的优化方法。该方法将平衡RFID标签天线等效为双端口网络,通过联合使用端口短路、开路延伸方法测量S参数,根据拐点选取最邻近数据并进行区间的数据拟合,从而计算出天线阻抗。首先 h1 进行了测量理论分析．然后设计了实物测量场景（915MHz频段的RFID天线）,并将该优化方法与传统的Bahm方法、无延伸单端口方法、延伸单端口方法进行了对比。结果表明,在工作频段内,该优化方法所测的标签天线的阻抗实部,虚部与仿真结果基本一致,比传统的Balun2及单端口等测摄方法准确;在工作频段外,所测阻抗实部仍然与仿真结果接近,尽管阻抗虚部与仿真结果存在一定的偏差。     

装备贮存可靠性评定方法

对军用装备的贮存可靠性指标予以统计指标，对装备系统常见的有性能参数要求的机械、电子整机，有强度要求的结构件整机和一次性使用产品等三大类型军用装备的贮存可靠性给出定量评定的模型。     

Method for the Characterization of Extreme-Ultraviolet Photoresist Outgassing

Outgassing from photoresists illuminated by extreme ultraviolet radiation can lead to degradation of the very expensive multilayer-coated optics in an extreme ultraviolet stepper. Reliable quantification of the various organic molecules outgassed by photoresists has been a challenging goal. We have designed a compact system for this measurement. In the first step, the total number of molecules emitted by the photoresist is measured using a pressure-rise method in a closed vacuum chamber, with the pressure measured by mechanical means using a capacitance displacement gauge. To provide identification and relative abundances, the outgassed molecules are then collected in an evacuated trap cooled by liquid nitrogen for subsequent analysis by gas chromatography with mass spectrometry. We will discuss the design and performance of the system.     

一种化学危害风险评估方法的探讨

本文阐述了目前我国风险评估工作中的关键技术问题,并以"专家评分法"与"风险矩阵法"为核心,提出了一种化学危害风险评估方法.     

一种新的符合性评定方法设计与分析

符合性评定是依据系统规则来评判被测量满足技术指标要求的程度.但在实际测试中存在测量结果及其测量不确定度区间非常接近甚至包含了指标"规范限"的情况,使得根据测量结果信息无法做出决策评定.为此本文提出新的符合性评定"两步法",给出了基于测量值及其测量不确定度的符合性评定规则,解决通常符合性评定中一步测试往往无法得出确切结果...     

Dipole Approximation for Electrically Small Loop Antennas

Measurement Techniques - An elementary magnetic emitter is considered as an approximation for the variable magnetic field of an electrically small radiating loop antenna. The frequency limits for...     

A Method for Improving Multivariate Measurement Systems Assessment

Multivariate measurement systems analysis (MSA) is usually performed by designing suitable gauge repeatability and reproducibility (R&R) experiments, ignoring available data generated by the measurement system while used for inspection or process control. This article proposes an approach that, by using the data that are routinely available from the regular operation of the instrument, allows the measurement instrument's current precision to be compared against a benchmark. The proposed method may be appropriately used in an integrated and coordinated manner with the usual multivariate gauge study in the sense that it can be used to assess the stability or a possible deterioration in the precision of the measurement instrument while operational. Therefore, the complementary use of the proposed approach and the traditional multivariate gauge R&R studies can be a useful strategy for improving the overall quality of multivariate measurement systems. Furthermore, because it can be implemented at almost no additional cost, it may be effective in reducing the costs of a multivariate MSA performed with a certain frequency. Copyright © 2014 John Wiley & Sons, Ltd.     

A Method for Instant Assessment and Active Learning

Abstract A method that provides tremendous benefits to both instructors and students is described in this paper. The method is based on asking a multiple choice question after every 10 to 20 minutes of a lecture and getting responses from all the students. The students respond by raising a card which displays the letter corresponding to their choice of answer. The method is easy to implement in any traditional lecture setting. It provides instant assessment of student learning and lets an instructor take corrective measure, if necessary, in the same class period. The method allows all the students in a class to actively participate, evaluate their own performance, and reflect upon what they have learned. The method works well either in a small or a large class and it typically creates an atmosphere of fun and learning in the classroom.     

Calibration Method and Uncertainty Assessment of a High-Temperature GHP Apparatus

In this research, a calibration method of a high-temperature guarded hot plate (GHP) apparatus was proposed in order to improve the measurement accuracy of thermal conductivity. The measurement uncertainties of this GHP apparatus were assessed to validate the reliability of this calibration method. The temperature difference across the guarded gap was set as the bias value to eliminate the heat exchange over the guarded gap. The effects of the thermal expansion and pressure of the apparatus on thickness were investigated to revise the measurement results of in-situ thickness and meter area, respectively. The assessed uncertainty indicated that the related expanded uncertainty approximately increased with the increase in testing temperature and the calibration method should be valid in the temperature range. The contribution of each factor on the combined uncertainty showed that the temperature distribution in plane direction was the main factor in influencing the measurement of thermal conductivity.     

区域水资源可持续利用评价理论模型与方法

文章在论述区域水资源可持续利用与水资源承载能力关系的前提下,提出了区域水资源可持续利用评价的模糊模式识别理论、模型和方法。应用所建立的模型对汉中盆地水资源可持续利用的程度进行了评价,应用实例表明,理论模型严谨,方法简洁,评价结果合理可行。此方法也可用于区域社会经济可持续发展等的评价。     

Near-Field Gain Correction for Transmission between Horn Antennas

When the gain of a horn antenna is to be measured from the power transmission loss between it and a standard horn, the Friis transmission formula must be corrected if the horn separation is not considerably greater than 2d2/?. Expressions for the correction between a pyramidal horn and a conical horn, and between dissimilar pyramidal horns, are presented with sample results. A method of applying these corrections to minimize the errors in the horn gain measurements is described.     

中航时平台惯导系统导航精度的全误差评估方法

平台惯导系统(PINS)初始对准误差和标定参数重复性是评估PINS精度的主要参数.应用给定精度评定指标无法准确评估PINS导航精度,PINS全误差导航模型能够准确描述PINS误差传播过程,但对多批次中航时PINS精度评估需消耗大量时间,缺乏实用性.结合实际应用中需要对每一台PINS中航时导航精度进行快速准确评估的需求,通过对PINS全误差导航模型传播规律进行分析,得到PINS误差参数对导航精度的单项评估公式和简化综合评估公式.数值仿真验证表明:该方法能够对中航时PINS导航精度进行快速准确估算,在PINS选择中具有很好的实用性.同时该方法可以指导惯导系统生产调试,找到影响惯导系统的主要误差因素,对改进设计、提高精度和精度评定具有参考价值.     

视频质量评价中时域信息检测的新方法

针对视频质量评测中时域信息的检测方法,本文提出了新的计算方法.该方法根据 ANSI TI.801.03-1996和ITU-TRecommendationP.910时域信息(TI)的概念定义和方法推荐,采用先对时域梯度图求直方图,再在所求直方图的基础上进行统计计算的方式,克服了直接进行时域梯度RMS计算带来的乘法运算量与画面像素数成正比从而导致耗时较多的缺陷.实验结果表明,采用本改进方式的乘法运算量仅取决于直方图的灰度级,而与具体像素数无关,在同等条件下的平均计算效率可提高约三倍,且对时域信息的检测效果与推荐方法相仿.该方法实现简单,易于集成,在视频质量评测应用中具有较好的推广价值.     

Close-Packed Silicon Lens Antennas for Millimeter-Wave MKID Camera

We have been developing a large-format millimeter-wave camera based on lens-antenna-coupled microwave kinetic inductance detectors (MKIDs) for a planned telescope at Dome Fuji (3810 m a.s.l.), Antarctica. Optical coupling to the MKID incorporates double-slot antennas and a silicon lens array. To realize a large-format camera ( \(>\) 10,000 pixels), a highly integrated small-diameter lens array and fast optics are required. Lens diameters of 1.2, 2, and 3 times the target wavelength are investigated for the main beam symmetry, side-lobe level, cross-polarization level, and bandwidth, considering the effects of the surrounding lenses. In this study, we present the simulated beam pattern profiles of close-packed lens antenna and the effect of misalignment between the silicon lens and double-slot antenna. We also show the evaluations of the developed 721-pixel close-packed silicon lens array.     

一种新型的压电材料参数的精确表征方法

针对压电材料精确表征问题,本文提出了一种包含材料损耗特性,基于模拟退火(Simulated Annealing,SA)优化算法的压电材料新型表征方法.并采用提出的新型表征方法对厚度振动模式下的高损耗偏铌酸铅压电陶瓷和l-3型压电复合材料样品的材料特性进行了研究,样品电子阻抗共振特性的理论优化结果与实际测量值准确拟合,表明该方法能够精确表征具有损耗特性压电材料参数.     

A Method for the Optical Characterization of Thin Uniaxial Samples

An optical characterization procedure for small fragments of uniaxial materials is described involving the simple use of crossed polarizers with one polished face of the material. The reflectance at a fluid-uniaxial slab boundary beyond, but near, the critical angle of incident light is examined for linear incidence polarization using an orthogonal output polarizer. It is found that, as the crossed incident and output polarizers are rotated together, there are, for a given angle of incidence, particular polarization angles for which the reflectivity is a minimum. These angles give information on the optical tensor of the crystal under study. Further the intensity of the reflected light, for incidence angles beyond critical with the input and output polarizers crossed, has as a function of the incident polarization angle an oscillatory form which, when fitted to theory, can also yield the full uniaxial tensor of the material under study. This is confirmed experimentally for a thin single crystal of calcite with one polished face.