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物理学是一门以实验为基础的科学,测量一个物理量必须使用测量仪器。各种测量都会涉及两个基本概念:精密度和准确度.在物理实验里,一个测量要怎样做才能测得精密?哪些因素影响实验仪器的精密度?有效数字怎样反映精密的程度?量具仪表的精度又有何含义?本文结合实验误差理论,从测量及常用量具仪表方面谈谈物理实验中的准确度与精密度的概念。 相似文献
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PASCO转动运动传感器可以精准地测量并实时地记录物体转动时的角速度。在落体法测量刚体转动惯量的实验中,为了提高实验的精度,将PASCO转动运动传感器与刚体转动惯量实验仪相结合,用PASCO转动运动传感器直接测量角速度并计算角加速度。改进后的仪器简化了实验步骤,提高了实验精度。对圆盘、圆环和圆柱试样的转动惯量进行测量,三组实验的相对误差分别为0.2%、0.7%和0.3%,实验结果准确。通过实验结果可得,改进后的实验仪器操作简单且测量精度很高。 相似文献
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如何测量额定电压为3.8V的小灯泡的额定功率呢?因为3.8V大于3V,因此不能直接用电压表0~3V的量程测量小灯泡两端的电压;但是如果实验中用电压表0~15V的量程测量小灯泡两端的电压,由于0~15V的量程的分度值是0.5V,就无法准确测量3.8V的电压,因此,这个实验并不能准确测量小灯泡的额定功率.那么能不能设法准确测量额定电压为3.8V的小灯泡的额定功率呢? 相似文献
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介绍了HL-2A欧姆电源及其逻辑无环流运行方式。用于判断负载电流过零点的变流器状态检测器通过监测变流器每个晶闸管桥臂的状态来判断负载电流是否为零,克服了直接测量负载电流精度低、可靠性差的不足。此检测器的响应时间可达1ms。欧姆电源运行在逻辑无环流方式下可使欧姆变压器的伏秒数得到充分利用,提高装置的放电参数,等离子体电流可达420kA。 相似文献
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飞机机载电源系统供电品质直接关系到飞机用电设备可靠工作和飞行安全,为此,2006年国际标准组织推出了新的机载电源标准ISO1540-2006;本文根据该标准要求,提出了一种机载电源的稳态和瞬态特性的测试的实用方法;建立了测量的数学模型;采用虚拟仪器技术,设计硬件测试平台,包括功率因数可调的大功率数字化程控负载和计算机数据采集系统;基于LabVIEW开发了测试软件;为满足暂态特性的测量要求和精度要求,采用了NI高速高精度数据采集卡,实现了较高的测量精度,综合测量误差小于0.5%,并在暂态测量中,考虑了负载接触器吸合时间;该测试系统可以用来检验恒频机载交流电源的特性是否符合国际标准要求,以保证飞行安全。 相似文献
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An essential step towards improving sound insulation is a reliable means of quantifying the performance. However, for various reasons sound insulation measurements at low frequencies are associated with relatively high uncertainty and wide variance values. The objective of this research is to develop a method of sound insulation measurement which complements the standard ISO 140 measurement methods by providing improved accuracy at low frequencies. In this paper part of the problem is considered, namely the measurement of power radiated into the receiver room. The ‘peak envelope method’ is based on mode theory and the measurement employs a pair of microphones in the receiver room and a calibrated volume velocity source. No reverberation time measurements are required. The theory is outlined and computer simulations and trial measurements are carried out in order to validate the theory. Good agreement in numerical and experimental validation is demonstrated. We conclude that the peak envelope method is suitable for the measurement of radiated sound power at modal frequencies where ISO 140 methods are poorly adapted. In order to obtain transmission loss, a measure of incident power in the source room will also be required, which will be the subject of future works. 相似文献
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城市空气质量监测系统(DOAS)谱线漂移问题及解决方法 总被引:2,自引:0,他引:2
城市空气质量监测系统中差分光学吸收光谱法的光学部分受到外界影响(温度、光纤位置等),或是氙灯自身的变化,都会引起测量谱线的漂移。如果灯信号谱与大气测量信号谱谱线漂移不一致而产生谱线相对偏移,将直接影响测量结果的准确性。因此,在运用DOAS方法进行大气痕量气体污染物浓度反演时,必须对大气测量信号谱和灯信号谱进行波长匹配。文章通过对氙灯自身发射光谱特殊结构的研究,提出了利用氙灯特征发射峰,通过对两个信号光谱进行最小二乘拟合,达到谱线校正的方法。实验结果证明,这种方法可以有效地减小谱线相对偏移对大气痕量气体污染物浓度反演结果的影响。 相似文献
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In situ Hall effect measurement of HgSe was conducted up to 31?GPa. It was found that the carrier parameters changed discontinuously at each phase transition. The resistivity variation under compression was described by the carrier parameters. The decrease in cinnabar mobility indicates that the interaction between the helical chains becomes stronger under pressure. Combining the results of experiment and theory calculation, it can be concluded that in the phase transition process from zinc blende through cinnabar to rock salt, if Hg atom is mainly displaced , hole will be generated and its concentration will increase; on the contrary, if Se atom is mainly displaced, electrons will be generated and their concentration will increase. 相似文献
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Experimental setup for tilt measurement and a novel signal detection method for demodulation of fiber Bragg grating (FBG) wavelength shift are proposed. Being attached, respectively, on the upper and lower surface of only one single pendulum-type cantilever element, only a couple of matched FBGs are used for both tilt angle sensing and wavelength shift signal demodulating. So the received light power will change due to the split of the two reflected spectra of FBGs, which corresponds to the tilt angle. In addition, the cross-sensitivity effect of FBG-based sensors will be solved automatically due to a differential signal process method. Experimental results indicate the measurement accuracy is about ± 0.03°, and measurement resolution is estimated to be about 0.002°. 相似文献
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MING Ruisen 《声学学报:英文版》1996,(4)
I.IntroductionOfallstructuralwaves,bendingwaveismostimportant.Itiseasilyexcitedandresultsinairbornenoiseradiation'Inpractice,itisnecessarytodeterminetheenergydistributionandpowertransmissionincoupledstructl1res.Bendingwaveenergycanbecalculatedfrombendingwaveaccelerationwhilebendingwavepowertransmissionischaracterizedbybendingwaveintensitywhichisavectorgivillgthemagnitudeanddirection.TheengineeringaPplicationofthevectorpropertyofbendingwaveilltensityisnumerous[1~3]buttheinvestigationinitispre… 相似文献
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根据同步光与储存环中的束流信号具有相同的时间结构的原理,测量同步光脉冲的半高全宽值可以计算出束团的长度。根据合肥光源的特点和实际需要,选择快速光电接收器搭配高速高带宽示波器作为在线测量束团长度和纵向分布等的主要手段。对单束团模式下束团长度随流强和高频腔腔压的变化趋势进行了测量。测量结果表明:束团长度与腔压的0.3次方成反比,比理论值0.5小;而束团长度随流强的增长率为2.0 ps/mA。通过测量纵向量子寿命进行了能散随流强变化的间接测量,结果表明,束团的拉伸是能散变化和势阱效应共同作用的结果。 相似文献
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By utilizing Monte-Carlo simulation technology, the centroid algorithms have been compared in detail. The factors such as the detected window size, threshold and weighting power factor, which affect the detected accuracy of the wavefront sensor, have been studied and the optimal parameters for each algorithm have been found. The numerical results will be helpful for further improving the measurement accuracy of the wavefront sensor. 相似文献
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血糖浓度的准确检测对于糖尿病的治疗具有重要的意义.本文采用连续幂系数回归方法有效地提高了近红外无创检测人体血糖浓度的预测精度.该方法是传统偏最小二乘法(PLS)的扩展,实现简易,且当幂系数选取恰当时,能够明显地提高预测精度.应用该方法分别建立了四成分葡萄糖实验和人体口服葡萄糖实验的定量分析模型,并利用该模型对预测集样本进行预测.实验结果表明,与PLS相比,该方法建立的定量分析模型不仅可以提高预测精度,而且可以针对不同的测量对象没定不同的幂系数以达到最佳的建模效果.根据不同个体灵活地选取幂系数,对于人体血糖浓度近红外无创检测研究具有很大的应用价值. 相似文献
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神龙一号电子束束参数测量系统猝发式的精确触发方式研究 总被引:1,自引:0,他引:1
为了准确了解电子束随时间变化的性能, 在神龙一号直线感应加速器上进行电子束束参数测量时要求测量系统精确地同步于电子束的产生和输运. 其功率系统开关放电波形后沿幅度高达250kV, 下降时间约20ns, 并且从该下降沿到电子束打靶的时间有145ns, 抖动1—2ns, 非常稳定; 如果以陡峭的后沿作为测量时间基准, 则可以获得与其抖动相同量级的同步精度. 因此通过对其波形的下降沿进行微分来获取测量系统的触发信号, 选择合适的微分参数可以得到对应于下降沿
约ns级精度的测量时间基准, 通过采用光纤驱动电路完全消除了高压开关对低压测量系统的干扰, 保证测量系统正常工作. 该方法消除了传统触发方式因延时长、精度低、抖动大等对确定测量时间基准的不利影响, 满足了使用高速测量设备准确获取电子束不同时刻的束参数波形的精确触发要求. 相似文献