The measurement of atmospheric water vapor: radiometer comparisonand spatial variations

Two water vapor radiometer (WVR) experiments were conducted to evaluate whether such instruments are both suitable and necessary to correct for propagation effects that are induced by precipitable water vapor (PWV) on signals from the Global Positioning System (GPS) and Very Long Baseline Interferometry (VLBI). WVRs are suitable for these corrections if they provide wet path delays to better than 0.5 cm. They are needed if spatial variations of PWV result in complicated, direction-dependent propagation effects that are too complex to be parameterized in the GPS or VLBI geodetic solution. In the first experiment, the suitability of radiometers were addressed by comparing six WVRs at Stapleton International Airport in Denver, Colorado, for two weeks. The second experiment addressed the question whether radiometers are needed for the detection of inhomogeneities in the wet delay. Three JPL D-series radiometers were operated at three sites in Colorado approximately 50 km apart. The WVRs simultaneously sampled PWV at different azimuths and elevations in search of spatial variations of PWV     

汽车制动检测装置两种标定方法的对比

对比了汽车制动检测装置的2种标定方法,砝码直接施压的标定方法和用仪表将滚筒向上拉的标定方法。通过实验知道这2种方法得出的实验数据基本相同;再通过对这2种方法在实际应用中的优缺点比较,得出用仪表将滚筒向上拉的标定方法更加准确。因此综合整个标定过程,提出了用仪表将滚筒向上拉的标定方法,以便得到更加准确的测量结果。     

金蒸气激光器的实验研究

介绍了金蒸气激光器的结构，给出了激光输出特性与工作温度、重复频率、Ｎｅ气压力关系的实验结果。     

Reduced water vapor transmission rates of low-temperature-processed and sol-gel-derived titanium oxide thin films on flexible substrates

Sol-gel-derived, crack-free, and condensed TiO_x thin films with improved barrier properties were successfully fabricated on polymeric substrates with a simple two-step heat treatment at low temperatures. To assess the barrier properties of the TiO_x thin films, Ca corrosion tests were conducted and their water vapor transmission rates (WVTRs) were measured. We found that the two-step heat treatment (at 45 °C for 90 min and 110 °C for 60 min) produces a close-packed TiO_x structure that substantially reduces the WVTRs of the coated polymeric substrates. The WVTRs of 86 nm thick TiOx thin films on polyethylene naphthalate (PEN) substrates at a relative humidity (RH) of 90% were found to be 0.133 g m⁻² day⁻¹ at 38 °C and 0.0387 g m⁻² day⁻¹ at 25 °C. In addition, the WVTR value of the TiO_x thin films on PEN substrates are stable with respect to bending: it was found to increase by only ∼13% after 100 repetitions of bending with a 20 mm radius.     

柔性金属膜封装器件的水汽阻隔性能研究

通过UV树脂和柔性金属薄膜将干燥片和透气绝缘的聚二甲基硅氧烷(PDMS)膜封装在器件中, 利用钙(Ca)膜电学测试方法测定封装结构的水汽透过率 (WVTR),研究了该封装方法的水汽阻隔性能。实验结果表明, Ca膜蒸镀时的温度调控极大影响Ca膜均 匀性和表面形貌,从而影响器件的水汽透过率检测结果。本文提出的柔性金属封装方法具有 良好的水汽阻 隔性能,其WVTR在封装90h后仍达到5×10－4 g/m²/day 以下,水汽主要从器件周围的UV树脂渗透,与传统薄膜封装的水汽渗透机制有很大不同。     

有机/无机/有机结构的封装薄膜水汽透过率研究

为了减少原子层沉积(ALD)方法在氧化物薄膜制备过程中ALD反应气对有机电致发光器件(OLED)性能的影响,利用旋涂光交联聚合物技术,直接在OLED上形成有机/无机/有机3层结构的保护薄膜。通过扫描电子显微镜(SEM)、原子力显微镜(AFM)的表面形貌分析表明,3层结构的封装薄膜表面平滑且致密,减少水(H2O)汽在氧化物表面积聚,降低H2O对氧化物薄膜的腐蚀作用,且成膜过程对OLED的各功能层没有伤害。经Ca薄膜的电学方法测量证明,这种3层结构的封装薄膜对气体有极高的阻隔作用,其H2O汽透过率(WVTR)可以达到9.0×10-5 g/(m2·day),从而实现了对OLED的有效保护。     

弹头表面轮廓测量方法的探讨

本文讨论了弹头表面轮廓测量的五种非接触测量方法的测量原理和各种测量方法的优缺点 ,并且对三角法提出了改进措施 ,引入球面坐标系 ,把大测量范围转换为小测量范围 ,从而大大提高测量精度。     

基于BP神经网络的水蒸气红外透过率仿真

针对在计算大气透过率方法中利用经验公式误 差大和专业软件复杂低效等问题,提出了一种基于 贝叶斯正则化BP(back propagation)神经网络的水蒸气红外透过率的计算方法。利用BP 神 经网络良好的非线性拟合特点,建 立大气参数与水蒸气透过率之间的关系模型。以实测温度、压强和湿度作为输入向量,中红 外平均水蒸气 透过率作为输出,构建3-7-1式的BP神经网络。仿真结果表明: 在相同的大气参数下,与逐线积分法相比, 本文方法在运算过程大幅简化的同时相对误差很小;与经验公式法相比,本文方法对透过率 的计算精度大幅提升。     

A comparison of motion-compensated interlace-to-progressive conversion methods

The conversion of interlaced video to progressive format may be carried out in a number of ways, including vertical interpolation, fixed or motion-compensated vertical-temporal interpolation, and approaches based on motion compensation using non-uniform sampling theory. Motion-compensated methods potentially offer the best performance, although the accuracy and reliability of the vectors has a significant impact on their performance. For applications such as display conversion using vectors recovered from an MPEG-2 bitstream, the vectors available may not be of the highest quality. This paper considers several motion-compensated interlace-to-progressive conversion methods, and assesses their performance with both accurate and inaccurate vectors using objective and subjective techniques. The method found to work best uses a motion-compensated three-field vertical-temporal filter, in which the vertical component of the vector is rounded to the nearest even number of picture lines per field period. This method reduced the RMS error of converted picture sequences by almost 20% compared to simple vertical filtering when using vectors from an MPEG-2 bitstream. Conversely, some other motion-compensated methods were found to increase the error by a similar amount.     

振动台加速度幅值均匀度试验研究

作为满足振动试验必不可少的工具,好的振动试验系统可以保证试验件在不失真的情况下试验,使试验受控,然而,如果振动台台面加速度均匀度不好,就会导致发生过试验或欠试验等问题。以某型振动台为例,研究加速度均匀度的测试方法,通过试验分析加速度均匀度的分布规律,可以提高振动试验的精度。     

一种基于间接标靶法的微小推力测量技术

提出了一种基于间接标靶法的微小推力的测量方法。对测量原理进行了分析。利用该测量方法对一系列利用微机械技术 (MEMS)制作的微喷管的性能进行了测量。给出了在不同燃烧室压强和喉部尺寸时 ,微喷管推力的测量结果 ,并与数值研究结果进行了比较     

水汽紫外拉曼激光雷达分光系统研究

介绍了一种可用于工作波长在紫外波段的水汽拉曼激光雷达的分光系统,即利用石英三棱镜组合结构实现对激光雷达多波长回波信号的分光。对于266 nm发射波长,由于激光雷达接收的氧气(O2)、氮气(N2)、水汽(H2O)拉曼波长相隔较近,普通的滤光片难以满足要求,利用该分光系统,对其参数尤其是对棱镜间夹角和光束入射角的优化,可将大气中O2、N2、H2O的拉曼散射信号完全分开,使光电检测系统可在三个独立的通道分别接收O2、N2、H2O拉曼信号,从而反演大气中水汽及臭氧含量垂直分布廓线。应用计算机对分光系统进行了模拟计算,以实现分光系统参数的最佳匹配;在入射角约为36°,棱镜间夹角约为106°时,该分光系统可完全分开O2、N2、H2O拉曼信号。最后,用激光激发拉曼管内高压气体产生受激拉曼散射以模拟回波信号波长的实验方法对计算结果进行了验证和标定,结果表明,该分光系统应用于紫外水汽拉曼激光雷达系统具有可靠性和可行性。     

A comparison of two van-der-Pauw measurement configurations of resistivity

Based on the solution of an electrostatics boundary-value problem, this paper compares two van-der-Pauw-type measurement configurations of resistivity, with respect to the movement of the point-like voltage and current contacts away from the periphery of a thin, square sample. The movement involves both a reduction in the size of the contact array, without any change in its shape or orientation, and a displacement of its center. The formulas derived are applicable to any rigid displacement such that all contacts remain within the boundary of the sample, but only displacements parallel to the edges of the sample or along its diagonal are examined. Both arrays are square, with the first initially coinciding with the corners of the sample and the second initially having its corners centered on the edges of the sample. The solution indicates that the deviation from the ideal van der Pauw resistivity measurement is less sensitive to a reduction in the size of the undisplaced contact array when the first configuration is used. However, under displacements, the situation is complicated markedly by boundary effects, with the results depending on the direction of displacement and the size of the array.     

GIS现场密封性试验基本方法及判定标准

GIS密封性试验通称为检漏试验,是GIS现场交接试验的最重要项目之一。本文以广泛应用的上海唐山仪表厂生产的LF-ID检漏仪为例,着重探讨GIS现场检漏方法及判断标准。     

影响侵彻过载测量的因素分析

研究弹体侵彻过载特性具有重要意义,通过试验实测弹体过载,为系统研究过载特性提供可靠依据。目前,存储测试技术在高 g值侵彻过载测试技术中得到了较为广泛的应用。本文基于前人研究成果,总结并论述了影响弹体侵彻过载测量准确性的几个关键因素,提出提高测量精确度的部分解决方法,研究结论对保证测试结果的有效性具有重要的参考价值。     

基于ZigBee无线传感网络瞬态测温系统的设计

为了满足在静态爆轰过程中,温度高、变化迅速以及测试条件非常恶劣的测试可行性要求设计了一种基于ZigBee无线传感网络控制的静态爆轰瞬态测试装置.该装置取代传统的有线测试将无线通信技术引入到静态爆轰过程的瞬态高温测试中,组成一个完善的测试解决方案.在静态爆轰过程中瞬态高温测试背景下提出的,将存储测试技术和新兴的ZigBe...     

100Gb/s RZ-ODQPSK实现方法性能比较

光差分正交移相键控(0DQPSK)调制格式在高速光纤通信系统中有着巨大的应用潜力.文章给出了高速0DQPSK调制格式的三种实现方式(串联调制、并联调制和双驱动单调制器调制),在建立仿真模型的基础上,对光信噪比(0SNR)、色散、偏振模色散(PMD)以及光纤非线性四个方面的容纳能力进行了对比、分析和研究.     

哥德堡地区基于无线通讯网络的水汽密度监测分析

利用无线通讯网络中的微波链路来监测降雨和水汽等是大气环境监测的新技术之一。这个技术可以测量近地面的降雨强度和水汽密度等气象参数,具有时空分辨率高、成本低等优势。利用瑞典爱立信公司(Ericsson)提供的位于哥德堡地区E频段的微波通讯链路资料、位于链路一端的气象站1资料和由瑞典气象水文研究所(SMHI)气象网站提供的气象站2资料,对2017年06月13日至2017年07月13日近1个月的水汽密度进行反演计算和分析。结果表明:同一区域的不同地点处的气象要素有一定的差异性,同一区域的温度会有一定的浮动(0~4℃),两者之间的相关性为0. 87;微波通讯链路反演的水汽密度结果与研究区域的地面气象站1和气象站2测量结果有很好的一致性,两者之间的相关性分别为0. 89和0. 97,均方根误分别差为0. 75 g m3和0. 79 g m3;利用微波链路,与现有的湿度监测方法相比,可以为现有的天气监测网络提供额外的丰富的数据源。     

振动测试的教学实验设计

本文设计了一种振动测试的教学实验,通过实验学生可以了解机械振动的机理,掌握振动测试的原理,掌握信号采集的方法,并了解数据处理的相关知识.     

利用红外图像处理方法检测材料缺陷

由于物体的导热特性和红外成像系统的限制,系统所成红外图像中目标与背景的对比度普遍较低,目标边缘模糊,难于直接判读缺陷,对于异形构件更是如此.针对这一问题,在热传导原理的基础上,首先通过中值滤波、帧间滤波尽量减少噪声对红外图像的影响.接着运用受限拉普拉斯算法和高提升滤波加强图像轮廓信息.然后通过灰度分段线性变换对图像中的缺陷信息进行增强,突出缺陷,改善红外图像的视觉效果,使其中的缺陷更适合于人眼观察,最后通过边缘检测的方法将缺陷边缘提取出来.仿真实验结果表明:该检测方法可得到清晰、光滑的缺陷轮廓图像,是一种实用型红外缺陷检测方法.