Evaluation of aspects affecting measurement of three-axis accelerometers

In order to set integrated procedures involving geotechnical and structural aspects finalized to buildings diagnostics, uncertainty aspects are discussed concerning three-axis accelerometers and inclinometers for a distributed sensor network. This network allows to operate in a selective manner, preferring the most critical situations. To this aim, the main aspects affecting the measurement uncertainty of sensors to be used for building diagnostic should be known. As the firstly step of the uncertainty evaluation procedure, we focused on the calibration of sensors used for the task. The requirement of low cost and complexity of sensors and test benches was considered. Experimental results show that satisfactory calibration accuracy could be achieved, also for the low frequency range, 0–10 Hz. Systematic errors are minimized and main parameters affecting uncertainty are identified, such as: the motion positioning of the accelerometer with respect to the vertical axis, the imposed motion law, the parameter used as the reference and, finally, the real radial positioning of the sensor. Requirements to be satisfied by the sensor are also analysed.     

某型车载雷达天线同步举升系统仿真研究

雷达天线快速、稳定的架设和撤收是举升系统最基本的要求之一,为提高车载雷达机动性,对其举升系统的研究十分重要。通过对天线举升液压系统的分析,建立系统的数学模型,采用交叉耦合控制方式,利用AMESim和Simulink联合仿真技术对系统进行仿真研究,分析比较举升系统在有、无偏载情况下的同步特性。仿真结果表明:交叉耦合控制方式下该举升系统具有工作平稳、可靠性好以及同步精度高等优点。     

弹性冲击头横向冲击问题的计算方法

本文提出一种具有弹性冲击头的横向冲击问题的计算方法。     

Preschool children's mathematical knowledge: The effect of teacher "math talk."

This study examined the relation between the amount of mathematical input in the speech of preschool or day-care teachers and the growth of children's conventional mathematical knowledge over the school year. Three main findings emerged. First, there were marked individual differences in children's conventional mathematical knowledge by 4 years of age that were associated with socioeconomic status. Second, there were dramatic differences in the amount of math-related talk teachers provided. Third, and most important, the amount of teachers' math-related talk was significantly related to the growth of preschoolers' conventional mathematical knowledge over the school year but was unrelated to their math knowledge at the start of the school year. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Broad-Crested Weirs with Rectangular Compound Cross Sections

A series of laboratory experiments was performed in order to investigate the effects of width of the lower weir crest and step height of broad-crested weirs of rectangular compound cross section on the values of the discharge coefficient, the approach velocity coefficient, and the modular limit. For this purpose, nine different broad-crested weir models with rectangular compound cross sections and a model with a rectangular cross section were tested in a horizontal laboratory flume of 11.0 m length, 0.29 m width, and 0.70 m depth for a wide range of discharges. The compound cross sections were formed by a combination of three sets of step heights and three sets of lower weir crest widths. The sill-referenced heads at the approach channel and at the tailwater channel were measured in each experiment. The dependence of the discharge coefficient, approach velocity coefficient, and modular limit values on model parameters was investigated, and these quantities were compared with those of the broad-crested weir models with a rectangular cross section.     

智能型无主机扩音对讲电话系统的研制

研制了一种用于现代化大、中型生产企业中大范围、强噪声的生产场所的工业通信系统-智能型无主机扩音对讲电话系统，在系统结构设计的基础上，给出了绳路信令的传输格式，设计了系统硬件，编制了系统软件，并从软、硬件方面采取了抗干扰措施。     

Analysis and design of ribbon cables for high‐speed digital applications

Ribbon cables have been widely used as subsystem interconnections in a large number of digital systems, because they can convey numerous bits of a digital signal simultaneously. In this article, finite difference and finite difference time domain (FDTD) methods are used to analyze and optimize the electrostatic analysis design of ribbon cables, and measurements are used to verify the numerical results. © 2002 Wiley Periodicals, Inc. Int J RF and Microwave CAE 12: 148–158, 2002.     

单站雷达系统的极化匹配系数

在通讯系统中天线的极化匹配系数这一概念的基础上,根据雷达目标应用中的最优极化状态的分析,提出了单站雷达系统中天线的共极化匹配系数,交叉极化匹配系数和自适应极化匹配系数的新概念,并给出了便于计算的表达式。     

WTO — a deterministic approach to 4-fermion physics

The program WTO, which is designed for computing cross sections and other relevant observables in the e⁺e⁻ annihilation into four fermions, is described. The various quantities are computed over both a completely inclusive experimental set-up and a realistic one, i.e. with cuts on the final state energies, final state angles, scattering angles and final state invariant masses. Initial state QED corrections are included by means of the structure function approach while final state QCD corrections are applicable in their naive formulation. A gauge restoring mechanism is included according to the Fermion-Loop scheme. The program structure is highly modular and particular care has been devoted to computing efficiency and speed.     

7－12MeV活化截面测量和低能中子影响的校正

简述了７－１２ＭｅＶ能区由于有几种低能中子成分的存在给截面测量与评价带来的困难，及低能中子的扣除方法。并给出了此能区几个反应道的测量结果，以图的形式与国际同行数据作了比较。又以￣（５８）Ｎｉ（ｎ，ｐ）￣（５８）Ｃｏ反应为例，说明低能中子对Ｔ（ｄ，ｎ）￣４Ｈｅ中子源的影响，还给出了￣（５８）Ｎｉ（ｎ，ｐ）反应的评价曲线。