活塞式压缩机气阀运动规律的测试

简述了用变距离电容位移测定法对活塞式压缩机气阀运动规律进行测试的基本过程。介绍了变距离电容位移传感器的设计原理和结构 ,具有结构简单、位移变化产生的信号较大、受温度影响小和精度高的特点。对交流电桥的最佳选择做了详细讨论 ,使其达到桥路简单、组件少和性能稳定的要求。并提出一种用正交多项式法来处理标定曲线的数学方法 ,避免了采用最小二乘法解联立方程的繁琐过程 ,而且可以任意增加逼近多项式的次数。通过对 2ZA -1 /8小型活塞压缩机的气阀运动规律实测曲线的对比和分析 ,证明该测试方法切实可行 ,克服了其他类型的位移传感器破坏阀门结构、影响排气、改变阀片受力状态的缺点 ,更适应小型压缩机气阀的测定 ,能够为气阀的设计和改造工作提供较为准确和可靠的实验资料。     

半导体GaN功率开关器件灵敏度测试技术

测试半导体GaN功率开关器件灵敏度对掌握器件性能具有重要意义,提出一种新的半导体GaN功率开关器件灵敏度测试技术。通过分析半导体GaN功率开关器件的导通电阻与击穿电压关系、空穴电流与栅极电流关系掌握功率开关器件击穿机理,在此基础上,测试半导体GaN功率开关器件灵敏度;根据灵敏度测试原理与微频通道衰减值周期检查原理,测量功率开关器件微频信号功率和微频通道衰减值,汇总微频通道衰减值和最后一次开关灵敏时的衰减值,得到半导体GaN功率开关器件灵敏度。实验结果表明：所提测试技术测量半导体GaN功率开关器件灵敏度过程中,平均测试误差为0.03 dB,仅平均花费9.42ms,是一种高效、可靠的半导体GaN功率开关器件灵敏度测试技术。     

基于VB的齿轮误差检测虚拟仪器软件系统开发

提出齿轮误差检测虚拟仪器的概念 ,介绍采用可视化语言VB进行齿轮误差检测虚拟仪器软件系统的开发过程。该系统的开发 ,实现了齿轮误差检测的自动化、数字化、可视化、智能化 ,提高了检测的效率、精度和可靠性     

A new method to assess the power performance during a lifting task in young adults

This study designs and verifies a new test for evaluating performance during a lifting task. 32 young men performed deadlift to high pull with increasing weights, and deadlift and upright row with a previously established weight of 70% 6RM, either using a Smith machine or free weights. Peak and mean power were significantly higher during deadlift to high pull with free weights than on the Smith machine, however only at ⩾50 kg. Their maximal values were achieved at about 80% and 70% 1RM. The deadlift to high pull with free weights is a reliable test with ICC > 0.80 and SEM < 10% for mean power. It is also a sensitive test for distinguishing lifting performance among healthy young individuals. It may be applied in functional performance testing of college graduate students and office workers with a prevalently sedentary lifestyle as well as construction workers with job demands based on lifting tasks.     

Some Comments on Spectral Analysis of Time Series

The Average Run Length of a Cusum chart for controlling a normal mean is calculated by solving the systems of linear equations which approximate the integral equations for the required quantities. The accuracy of approximation by this method is numerically evaluated and the results are compared with those obtained by other approximate methods. The construction and use of a new nomogram based on the contours of Average Run Lengths L_a . and L_r drawn in the h√n/σ—|μ – k|√n/σ plane is discussed. Numerical examples are given to illustrate the flexibility and convenience provided by this nomogram in the design of Cusum charts.     

Feature extraction and soft computing methods for aerospace structure defect classification

This study concerns the effectiveness of several techniques and methods of signals processing and data interpretation for the diagnosis of aerospace structure defects. This is done by applying different known feature extraction methods, in addition to a new CBIR-based one; and some soft computing techniques including a recent HPC parallel implementation of the U-BRAIN learning algorithm on Non Destructive Testing data. The performance of the resulting detection systems are measured in terms of Accuracy, Sensitivity, Specificity, and Precision. Their effectiveness is evaluated by the Matthews correlation, the Area Under Curve (AUC), and the F-Measure. Several experiments are performed on a standard dataset of eddy current signal samples for aircraft structures. Our experimental results evidence that the key to a successful defect classifier is the feature extraction method – namely the novel CBIR-based one outperforms all the competitors – and they illustrate the greater effectiveness of the U-BRAIN algorithm and the MLP neural network among the soft computing methods in this kind of application.     

Confidence interval optimization for testing hypotheses under data with low statistics

The notion of a confidence interval (CI) is used in the both major sections of the mathematical statistics: parameter estimation and hypothesis testing. While estimating parameters a CI defines the bounds of the parameter estimates with a certain confidence probability, and while testing hypotheses a CI defines with a certain confidence probability an interval of values of the random variable which do not contradict the tested hypothesis about them.     

基于卫星导航系统地面段的可靠性测试方法研究

本文对卫星导航系统单机设备和地面运控系统分别作为研究对象进行了研究：根据单机设备的特性，分别研究了成败型测试方法、寿命型测试方法和应力一一强度型测试方法；根据地面运控系统的组成特点，进行了并联系统测试方法研究和串联系统测试方法研究，并在研究基础之上，提出了如何在后续系统研制建设过程中继续加强可靠性测试工作的对策。     

Producing mind

Those who support a computationalist view of the mind tend to hold that it must apply to all aspects of mentality. This view is called computational universalism. An apparently opposed perception-phenomenal universalism-is that consciousness is at the root of all mental processes. Computationalists tend to cognitivize, or otherwise play down, phenomenal consciousness. The recent book by David Chalmers proposes one way to take both computation and phenomenal consciousness seriously. A different way is explored here, which avoids the commitment to a non-materialist ontology of consciousness in Chalmers' position. This alternative approach rejects universalism of both the computational and the phenomenal kinds. Instead a pluralistic view of mind is proposed. Cognitive and phenomenal aspects of mind are to be taken as equally fundamental and as complementary. Cognitive or productive aspects of mind have their own kind of reality which is independent of consciousness. Semantic content may well result from the combination of cognitive productivity and consciousness. The view proposed offers solutions to old problems affecting computational accounts.     

Extension of Sample Sizes and Percentage Points for Significance Tests of Outlying Observations

Tables of percentage points for significance tests conrerning the highest or the lowest observation in normal samples, or the two highest or the two lowest observations in normal samples, were recently extended to larger sample sizes than heretofore published and to probability levels of .005 and .001. These tables are being pltblished to satisfy a long existing demand for such extensions.