彩电屏幕标注尺寸为何与实际不符?

市场上销售的74厘米(29英寸)彩电对角线的实际屏幕尺寸只有68厘米(27英寸),64厘米(25英时)彩电对角线的实际屏幕尺寸只有59厘米(23英寸),54厘米(21英寸)彩电对角线的实际尺寸只有51厘米(20英寸)。彩电名义尺寸与屏幕有效画面尺寸不同的原因是彩色显像管型号的不同命名法造成的。我国彩色显像管尺寸按彩管对角线最大外形尺寸标注,包括了玻壳尺寸,而不是按有效屏幕对角线实际尺寸标定。现将国际彩管型号命名法和国内彩管型号命名法介绍给大家,供参考。国际统一命名法:①字母②数字③字母④数字⑤字母④数字。第①部分:用一个字母、表示彩管用途,如电视用彩管用A表示,监示器用彩管用M表示,宽屏幕彩管用W表示。第②部分:二个数字表示荧光屏最小有效屏幕画面对角线尺寸,以cm计量。四舍五入取整数。第③部分:用三个字母(不使用I和O)组成。表示种类特征。其中第一个字母表示国别,后面按拉丁文顺序排列。第④部分:由二个数字表示某个系列管中的特定顺序号,单色管由一个数字组成。第⑤部分:采用字母表示荧光膜用荧光粉特性。对彩色电视机用彩色管,荧光粉用单一字母X表示。对黑白管用荧光粉     

平面度测量中采样点数据的归一处理

大平面平面度测量中采样点读数值的归一处理，根据测量布线方法的不同，可以采取不同的方法。常用的布线方法有对角线法和网格法，其中对角线法是国家检定规程JJGll7-9l规定的布线方法。由于网格布线法采样点读数值归一的方法计算简单，文章重点介绍对角线归一法的VB程序和验证过程，在验证过程中给出了数控测量机的平面度算法程序(DEAPPL语言)，给出了平面度的LSM和ISO计算结果，以证明对角线归一处理程序的正确性，也给出了平面度计算的另一准确有效方法。     

羟基磷灰石微载体的制备及生物相容性评价

采用酸碱中和滴定法制备羟基磷灰石(HA)粉末,X射线衍射分析仪(XRD)检测其相组成,结果表明其具有较高的纯度和结晶程度。以该粉末为原料通过喷雾干燥法制备出粒径合适的羟基磷灰石微载体,采用扫描电镜观察其形貌和粒径分布,并通过原子吸收法检测微载体浸提液对钙离子浓度的影响,MTT法检测微载体浸提液对细胞毒性的影响,IPP软件分析计算浸提液对细胞铺展的影响,细胞计数法分析浸提液对细胞增殖的影响。结果表明,微载体首次浸提液中钙离子浓度、细胞的活性、细胞的铺展以及细胞的增殖与对照组相比均有显著差异,二次浸提液与对照组相比均无显著差异,即二次浸泡后的微载体具有较好的生物相容性。     

两种近似评定平面度误差方法的比较

在评定平面度误差的方法中,“对角线法”和“最小二乘法”都是比较接近“最小条件”的方法。这两种方法哪个更接近最小条件呢?“用最小二乘法评定平面度误差”一文称:“最小二乘法与对角线法……相比较精确度要高得多”。我认为某些类型的平面,最小二乘法比对角线法更接近最小条件,而另一些类型则恰好相反。现以文献中的几个例子和我们测量工件时的两个实例(例5和例6)作对比,就可以说明这个问题。对比结果见下表。     

论对角线法评定平面度误差的计算

论对角线法评定平面度误差的计算北京市计量科学研究所张泰昌对角线法是以对角线平面为理想平面评定平面度的一种数据处理方法。对角线平面则是通过被测表面的一条对角线且与另一条对角线平行的平面。数据的处理是将水平仪或自准直仪得到的截面各点相对于该截面两端点连线...     

饮用水中挥发性三卤甲烷(THM)_s测定方法的改进

本文使用吹扫捕集法来前处理水样,用带有电子捕获检测(ECD)的气相色谱仪来测定水中三卤甲烷(THM)_s。水样加标回收率在85%～115%之间,相对标准偏差在5%左右。实验结果表明,该法具有简单、快速、灵敏的特点。     

使用单片机测频的四种方法分析——兼谈等精度测频法的实现

本文论述了使用单片机测频的四种方法,即直接计数法、周期测频法、混合测频法和等精度测频法。通过误差分析指出,直接计数法适于高频测量,周期测频法适于低频测量。在此基础上,提出具有通频带测频性质的混合测频法,并给出其测频最大相对误差和最大误差频率点的表达式。关于等精度测频法,提出利用软件查询实现同步的方法。并论证其测频精度可达10~(-6)     

对角线计算法探讨

用节距法测量平面度的数据处理,《平板检定规程》(JJG117—78)推荐使用“对角线计算法”。实际上该法仅仅是将观测结果统一到同一个基准面上,而没有解决由多余观测而引起的矛盾(中心点有三个偏差值)。或者说该法是最不合理的“保留矛盾的计算方法”(数     

季铵盐型脱细胞猪真皮基质的研究

以甲基丙烯酸二甲氨基乙酯(DMAM)、溴代十四烷(TB)为原料,合成了季铵盐型改性剂甲基丙烯酰氧乙基-十四烷基-二甲基溴化铵(DMAM-TB)。分别采用2.5%,5.0%,10.0%和20.0%(质量分数)的DMAM-TB改性脱细胞猪真皮基质材料,测定了其接触角、吸湿率、溶胀率以及毛细血管率,并采用抑菌圈法和菌落计数法研究了其抗菌性能。结果表明,随着DMAM-TB用量的增加,改性后的脱细胞猪真皮基质材料(DT-pADM)吸湿率、溶胀率以及毛细血管率明显升高,亲水性能增强;改性前pADM无抗菌性能,改性后的材料水洗前后对大肠杆菌和金黄色葡萄球菌都具有良好的抗菌性能,说明DMAM-TB已接枝到pADM上,并赋予了其相应功能。     

布氏和维氏硬度压痕的正确测量

布氏和维氏硬度试验压痕的正确测量,直接影响到被测试件的硬度值,因之不容忽视。常用的测量方法有: 1.单线测量——测量线移动法此种测量压痕的方法是先使测量线在压痕之左逐渐逼近压痕左缘,直至相切,记下读数(d_1)。参看图1。然后向右移动测量线,到与压痕之右缘相切为止(对维氏硬度压痕,测量线必须与对角线垂直)。再记下第二次读数(d_2),两次读数之差(d=d_2-d_1)即为压痕的直径(或对角线长)。由于只使用一条刻度线,故误差因素少。但测量线要移动整个压痕     

微囊藻细胞计数法研究

本文阐述了用超声波短时作用来处理水样,从而找到更科学地计数水体中微囊藻细胞数的方法。并通过实验进一步研究了超声波频率和作用时间对处理效果的影响。     

基于多普勒特征恢复的声矢量阵鲁棒自适应波束形成方法

在短快拍、信号导向矢量失配环境下,传统的自适应波束形成方法性能受到影响,对角加载技术是提高算法在复杂环境下性能鲁棒性的重要技术之一。针对水声环境和水声信号特点,提出一种基于声矢量阵的自适应波束形成方法。该方法利用水声信号的多普勒频率信息,在不同环境下自适应地选择最优对角加载因子,确定波束形成的权矢量,从而实现提取期望目标信号、抑制干扰和噪声的目的。无需任何用户参数,鲁棒性强、估计精度高。最后基于声矢量阵进行仿真实验,仿真结果证明了所提出的方法能够有效地获取目标信号,具有较好的抗干扰能力。     

An improved explicit finite element method for tidal flow

A weighting function by which the mass matrix is made to be diagonal is deduced on the two-dimensional simplex element. Adopting the weighted residual method with the deduced weighting function for spatial domain and the two-step Lax–Wendroff method for time differentiation, the two-dimensinoal tidal flow in a model basin is calculated by means of the explicit finite element method. The water mass transport integrated over one tidal period at some cross-sections of the basin is also estimated, in order to verify the water mass conservation. It is found that the water mass is nearly conserved in the present method, although the usual lumped mass matrix technique fails to conserve. The present explicit finite element method with the conservative form of governing equations is also investigated and the water mass conservation is found to be a little more improved in this case than in the case of non-conservative forms. Application to a real bay indicates that the method with the conservative form of equations could be used for the estimation of tidal residual flow.     

Analytical diagonal elements of regularized meshless method for regular domains of 2D Dirichlet Laplace problems

This note is to present a simple approach to derive the analytical formula of the diagonal elements of the interpolation matrix of the regularized meshless method (RMM) for regular domain problems, which is a very new boundary-type numerical discretization technique. In literature, these diagonal elements are mostly calculated numerically by the desingular technique, except for the circular domain problems. Our numerical experiments show that the analytical diagonal elements can improve the solution accuracy of the RMM for some regular domain problems, and the diagonal elements are critical to the solution accuracy of the RMM. Thus, a searching process is employed to find the optimal diagonal elements for RMM.     

Self-information-based weighted CUSUM charts for monitoring Poisson count data with varying sample sizes

In many applications, the Poisson count data with varying sample sizes are monitored using statistical process control charts. Among these applications, the weighted CUSUM charts are developed to deal with the effect of the varying sample sizes. However, some of them use limited information of the sample size or the count data while assigning the weights. To gain more information of the process, the self-information weight functions are developed based on both the sample size and the observed count data. Then, the weighted CUSUM charts are proposed with the self-information-based weight. Simulation studies show the self-information-based weighted CUSUM charts perform better than the benchmark methods in detecting small shifts. Moreover, the performance of proposed method with estimated parameters is investigated via simulation. Finally, an example is given to illustrate the application of the proposed weighted CUSUM charts.     

Utilizing spectral counting to quantitatively characterize tandem removal of abundant proteins (TRAP) in human plasma

Biomarker discovery efforts in serum and plasma are greatly hindered by the presence of high abundance proteins that prevent the detection and quantification of less abundant, yet biologically significant, proteins. The most common method for addressing this problem is to specifically remove the few abundant proteins through immunoaffinity depletion/subtraction. Herein, we improved upon this method by utilizing multiple depletion columns in series, so as to increase the efficiency of the abundant protein removal and augment the detection/identification of less abundant plasma proteins. Spectral counting was utilized to make quantitative comparisons between undepleted plasma, plasma depleted with a single depletion column, and plasma depleted using two or three depletion columns in tandem. In the undepleted plasma only 29 lower abundance protein groups were identified with the top-scoring protein from each group having a median spectral count of 3, while in the plasma processed using a single HSA depletion column 61 such protein groups were identified with a median spectral count of 8. In comparison, 76 lesser abundant protein groups were identified with a median spectral count of 11.5 in the two column setup (i.e., HSA followed by MARS Hu14). However, in the ultimate depleted plasma sample, which was created using three depletion columns in tandem, the number of less abundant protein groups identified increase to 81 and the median spectral count for the top-scoring proteins from each group increased to 15 counts per protein. Moreover, exogenous B-type natriuretic peptide-32, which was added to the plasma as a detection benchmark at 12 μg/mL, was only detected in the plasma sample depleted using three depletion columns in tandem. Collectively, these data demonstrate that this method, tandem removal of abundant proteins or TRAP, provides superior removal efficiency compared to traditional applications and improves the depth of proteome coverage in plasma.     

生活饮用水3M Petrifilm~(TM)菌落总数测试片法的不确定度评定

对3M PetrifilmTM菌落总数测试片法检测生活饮用水中菌落总数的测量结果进行了不确定度评定,评述了引起测量结果不确定度的主要因素,对样品稀释及方法精密度因素进行了详细评价,并对单一样品重复测量10次及30个样品每个样品平行测量2次的两种情况,分别进行了重复性标准偏差评价。结果显示:单一样品重复测量时,测量结果的不确定度主要由样品稀释和重复性标准偏差引起,扩展不确定度U95为20CFU/mL,k=2;多个样品每个样品平行测量2次时,测量结果的不确定度主要由重复性标准偏差引起,在95%的置信度时,扩展不确定度U(lgxj)为0.093,k=2.75。     

生活饮用水3M Petrifilm^TM菌落总数测试片法的不确定度评定

对3M PetrifilmTM菌落总数测试片法检测生活饮用水中菌落总数的测量结果进行了不确定度评定,评述了引起测量结果不确定度的主要因素,对样品稀释及方法精密度因素进行了详细评价,并对单一样品重复测量10次及30个样品每个样品平行测量2次的两种情况,分别进行了重复性标准偏差评价。结果显示：单一样品重复测量时,测量结果的不确定度主要由样品稀释和重复性标准偏差引起,扩展不确定度U95为20CFU/mL,k=2;多个样品每个样品平行测量2次时,测量结果的不确定度主要由重复性标准偏差引起,在95%的置信度时,扩展不确定度U（lgxj）为0.093,k=2.75。     

Influence matrix diagonal block elements for two‐dimensional elastodynamic problems

A method is described in this article to calculate the diagonal block elements of the influence matrices used in the boundary element method for two‐dimensional elastodynamic problems. Currently, a method that is used in the calculation of diagonal block elements is a combination of rigid‐body translation and Gaussian quadrature for the adjoining elements to the singularity point. This paper proposes to show an alternative method for the calculation of diagonal block elements of the traction influence matrix in elastodynamic problems where linear elements are used. In addition, the method is applied for use in the displacement influence matrix. The accuracy of the method is demonstrated in an example problem. Copyright © 1999 John Wiley & Sons, Ltd.     

A multivariate Poisson-lognormal regression model for prediction of crash counts by severity, using Bayesian methods

Numerous efforts have been devoted to investigating crash occurrence as related to roadway design features, environmental factors and traffic conditions. However, most of the research has relied on univariate count models; that is, traffic crash counts at different levels of severity are estimated separately, which may neglect shared information in unobserved error terms, reduce efficiency in parameter estimates, and lead to potential biases in sample databases. This paper offers a multivariate Poisson-lognormal (MVPLN) specification that simultaneously models crash counts by injury severity. The MVPLN specification allows for a more general correlation structure as well as overdispersion. This approach addresses several questions that are difficult to answer when estimating crash counts separately. Thanks to recent advances in crash modeling and Bayesian statistics, parameter estimation is done within the Bayesian paradigm, using a Gibbs Sampler and the Metropolis–Hastings (M–H) algorithms for crashes on Washington State rural two-lane highways. Estimation results from the MVPLN approach show statistically significant correlations between crash counts at different levels of injury severity. The non-zero diagonal elements suggest overdispersion in crash counts at all levels of severity. The results lend themselves to several recommendations for highway safety treatments and design policies. For example, wide lanes and shoulders are key for reducing crash frequencies, as are longer vertical curves.