高速传输系统CAD/CAM齿形误差最优化算法

本文提出了一种CAD/CAM齿形误差的最优化算法。本算法收敛速度快、拟合误差小,能够按照预定设计要求对齿形精度加以控制,实现最优化自动搜索,同时给出数值计算结果。     

Controlled decoherence of three-level rf-SQUID qubit with asymmetric potential

A scheme is proposed to controll the decoherence of three-level rf-SQUID qubit with asymmetric potential by designing an external electric circuit for superconductive flux qubit. The results show that it may not only raise the gate speed but also extend decoherence time for a three-level structure.     

He-Ne激光诱变的香菇变异株遗传稳定性分析

对三株香菇菌种采用He-Ne激光(λ=6328nm)进行两次照射,筛选出三株比出发菌株菌丝生长速率分别提高173%、737%和426%的变异株,经传代培养及酯酶同工酶谱分析,变异株具有良好的遗传稳定性表明激光作为微生物新型诱变因子与传统化因子相比,具有正变率高、回复突变率低、遗传稳定性好的特点.     

基于FPGA的超高速线阵CCD信号采集系统的设计与实现

线阵CCD已广泛应用于在线检测、图像识别等系统,目前高帧率采集系统多在200~500Hz之间。高速线阵CCD采集系统,如1K甚至10KHz以上的采集要求,设计难度大,电路实现复杂,需要专用处理器,产品成本高,提出了一种采用并行高速FPGA驱动线阵CCD,通过常规分立元件完成模拟信号处理,实现数字信号实时传输的方案。该方案不仅简化了硬件设计上的难度,在同等性能情况下,可实现每秒万帧的高速采样,大幅度降低了成本。方案选用Altera FPGA作为控制核心,实现高速信号采集的同时,在片上实现一定的图像算法,不仅加速了图像处理速度,同时降低了计算机的处理压力。最后,本电路通过USB2.0接口,完成数据的实时传输。设计具有高帧率、高灵敏度、性能稳定,便携使用等特点,同时还有一定的通用性,已应用于一些光学系统中。     

时间序列的变化点检测和趋势分析

趋势分析和变化点检测是时间序列分析中常用的工具. 变化点检测是识别过程行为的自然或人为的突然的变化,而趋势可以定义为对逐渐偏离过去的规范的估计. 本文使用了Cox-Stuart方法和变化点算法分析时间序列数据趋势的存在,并以澳大利亚的近地表风速时间序列为例. 澳大利亚的近地表风速趋势是根据研究出的新开发的风速数据集,通过使用局部表面粗糙度信息,以及不同高度收集的混合观测数据构建. 10 m处的风的速度趋势通常会增加,而2 m处则趋于减小. 假设检验测试,变化点分析和人工检查记录表明有几个因素可能是导致差异的原因,例如伴随仪器变化的系统性偏差,随机数据错误(例如累积日错误)和数据采样问题. 均质化以及基于变化点检测的技术和多期趋势分析阐明了风速趋势不一致的根源.     

深水域近水面水下爆炸水柱形态及演变实验研究

 为研究不同起爆深度的水下爆炸水柱形态及演变特征,进行了1 kg球形RDX装药在不同起爆深度下的海上爆炸实验,通过高速摄像机记录装药起爆后水柱的形成和成长过程,获得了喷射水柱形态的演变特征以及水柱高度、直径、水柱突出水面时间等参数的变化规律,并与Cole、Hole和Swisdak等人的研究结果进行对比分析。研究结果表明：对于深水域近水面水下爆炸,水柱以垂直喷射形态为主,当气泡在膨胀阶段到达水面时水柱存在微弱的径向飞散现象;水柱最大高度随起爆深度呈脉动变化,水柱直径随起爆深度线性减小;Swisdak关于水柱最大高度的计算公式不适用深水域近水面水下爆炸情况。     

An improved progressive preconditioning method for steady non‐cavitating and sheet‐cavitating flows

An improved progressive preconditioning method for analyzing steady inviscid and laminar flows around fully wetted and sheet‐cavitating hydrofoils is presented. The preconditioning matrix is adapted automatically from the pressure and/or velocity flow‐field by a power‐law relation. The cavitating calculations are based on a single fluid approach. In this approach, the liquid/vapour mixture is treated as a homogeneous fluid whose density is controlled by a barotropic state law. This physical model is integrated with a numerical resolution derived from the cell‐centered Jameson's finite volume algorithm. The stabilization is achieved via the second‐and fourth‐order artificial dissipation scheme. Explicit four‐step Runge–Kutta time integration is applied to achieve the steady‐state condition. Results presented in the paper focus on the pressure distribution on hydrofoils wall, velocity profiles, lift and drag forces, length of sheet cavitation, and effect of the power‐law preconditioning method on convergence speed. The results show satisfactory agreement with numerical and experimental works of others. The scheme has a progressive effect on the convergence speed. The results indicate that using the power‐law preconditioner improves the convergence rate, significantly. Copyright © 2010 John Wiley & Sons, Ltd.     

Comment on the paper: H.-E. Hwang, P. Han, Theoretical analysis for surface tilt and translation detection based on speckle photography in the Fresnel domain, Opt. Commun. 282 (2009) 351-354

In a recent paper [H.-E. Hwang, P. Han, Opt. Commun. 282 (2009) 351] a speckle based metrology system is proposed which it is claimed provides significant advantages over existing systems. In this paper, we show that the discussion presented in [H.-E. Hwang, P. Han, Opt. Commun. 282 (2009) 351] is deficient, and that several of the statements made are incorrect and/or misleading.     

Single‐run capillary electrophoresis method for the fast simultaneous determination of amoxicillin,clavulanate, and potassium

We report a new fast method for the simultaneous determination of amoxicillin, clavulanate, and potassium by capillary electrophoresis with capacitively coupled contactless conductivity detection. Samples containing potassium as the cation, and both amoxicillin and clavulanate as anions were determined simultaneously in a single run (in less than 45 s) using 10 mmol/L of both 2‐amino‐2‐hydroxymethyl‐propane‐1,3‐diol and 3‐{[2‐hydroxy‐1,1‐bis(hydroxymethyl)ethyl]amino}‐1‐propanesulfonic acid (pH 8.4) as the background electrolyte. Limits of detection were 25.0, 5.0, and 4.0 μmol/L for amoxicillin, clavulanate, and potassium, respectively. The proposed method is inexpensive, simple, fast (75 injections h⁻¹), environment friendly (minimal waste generation), and accurate (recovery values between 98 and 103%). The results obtained with the proposed method were statistically similar (95% confidence level) to those obtained by using high‐performance liquid chromatography (amoxicillin and clavulanate) and flame photometry (potassium).     

Steady state speed distribution analysis for a combined cellular automaton traffic model

Cellular Automaton （CA） based traffic flow models have been extensively studied due to their effectiveness and simplicity in recent years. This paper develops a discrete time Markov chain （DTMC） analytical framework for a Nagel-Schreckenberg and Fukui Ishibashi combined CA model （W^2H traffic flow model） from microscopic point of view to capture the macroscopic steady state speed distributions. The inter-vehicle spacing Maxkov chain and the steady state speed Markov chain are proved to be irreducible and ergodic. The theoretical speed probability distributions depending on the traffic density and stochastic delay probability are in good accordance with numerical simulations. The derived fundamental diagram of the average speed from theoretical speed distributions is equivalent to the results in the previous work.