River Bifurcation Analysis by Physical and Numerical Modeling

In the framework of a river regulation design of the Po River Delta (Northern Italy), a study on a large physical model of the bifurcation Po di Goro-Po di Venezia was conducted with the main objective of determining the discharge subdivision rate at the river node, in order to assess the inflow conditions in the Po di Goro River for flood risk analysis. In this context, a two-dimensional depth averaged numerical model was tested against measured values, with reference to the prototype. In this paper a comprehensive analysis and discussion of the results is reported in order to highlight the applicability of numerical models in comparison with physical ones in river engineering applications.     

北京谱仪漂移室读出电子学校准电路

本文介绍的电路可同时进行时间和电荷校准,它的校准量程大,精度高,稳定性好,可输出864路指数形校准信号,并可手动或程控。它的时间校准精度优于±250ps,电荷量校准精度优于±1％。     

Intercomparison of scanning probe microscopes

Comparison measurements on reference standards are reported in which 13 partners with different instruments took part. A set of prototype standards which had been produced and calibrated within a European project were used for the measurements. Here, results of measurements on a 240 nm step height standard and a two-dimensional lateral standard with a nominal pitch of 1 μm are reported.     

Probabilistic analysis of a static frame model

This paper describes our efforts during our participation in the Sandia Validation Workshop. The focus of the paper is the calibration of material models and simulation of random fields to characterize the variations of material properties across spatial field. Both parametric and non-parametric methods were used to represent uncertainty. Part of the challenge of this problem is the small amount of data that is available for the necessary probabilistic analyses in support of calibration, validation, accreditation and prediction activities. The analysis methods and corresponding results are described.     

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当前我国管道天然气计量系以体积表示，就其计量器具而言，差压式流量计、容积式流量计和速变式流量计都有，但大流量计量大多仍采用标准孔板差压式流量计，其流量计量标准招待我国SY／T6143－1996《天然气流量的标准孔板计量方法》。文章介绍目前常用的三种流量计的优缺点比较；天然气标准孔板差压式流量计算机自动计量系统的检定，其中包括：标准孔板节流装置，静压、差压变送器、温度传感器、数据采集系统等组件的检定；以及计量器具的正确使用和维护。最后，文章指出目前流量计量的发展主要是二次仪表的发展，籍助应用计算机大大提高流量法的测量范围和准确度，但对用户来说，应选择性／价比合适的仪表，并要考虑所选用仪表要便于检定、维护，同时，计量检定部门则应跟上发展，为广大用户提供技术支持。     

标准椅全身计数器对不同年龄组均匀体模源全能峰效率的刻度

本文介绍了用标准液体源均匀充入聚氯乙烯制的体模,刻度标准椅全身计数器〔φ8″×4″(NaI)〕的方法和结果。分别就代表6个年龄组的体模,测定了标准椅全身计数器对5种能量(364,637,898,1460和1836keV)γ射线的全能峰效率;给出了全能峰效率与γ射线能量和被测对象体重的关系曲线。     

空气中^131I的取样和测量方法的研究

本文介绍一种气态和气载~(131)I 取样器。着重介绍了一种指数分布源的效率刻度方法,讨论了与取样有关的一些问题。     

球形电离室型周围剂量当量计的实验研究

本文报道了根据国际辐射单位与测量委员会（ＩＣＲＵ）３９号报告推荐的用于环境或工作场所监测的周围剂量当量Ｈ＾＊（ｄ）的定义以及ＩＣＲＵ对其能量响应的要求所研制的球形电离室型周围剂量当量计，并对其主要性能进行了实验研究，刻度了响应因子。