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11.
ABSTRACTMicrostructure and mechanical properties of laser solid formed 30Cr–Mn–Si–Ni–2A steel are investigated. The deposits consist of epitaxial columnar grains, equiaxed grains or direction changed dendrites can be observed in the bulk specimens. The microstructure at the bottom of deposits is mainly composed of tempered martensite; the middle to top zone of the deposits are characterised by martensite and bainite. With the increasing of deposition height, the volume fraction of bainite increases, the size of martensite laths increases but its volume fraction decreases. The microhardness shows a decrease from the bottom zone to the middle–upper zone, and then a significant increase at the top of the deposits. Anisotropic and unevenly distributed tensile properties are observed for the deposits. Samples after heat treatment demonstrate tensile strength of 1720?MPa and elongation rate of 8.7%. 相似文献
12.
在立洲水电站大坝高边坡开挖过程中,其坝肩边坡马道层与层之间的高差达30 m,通过30 m孔深一次预裂爆破,达到了技术要求,同时提高了施工进度及经济效益。30 m深孔预裂爆破在该工程的成功运用,给同类工程提供了参考和借鉴。 相似文献
13.
针对具有霍尔传感器的无刷直流电动机,以dsPIC30F3010为核心控制芯片,绘制出系统的总体设计框图,同时采用空间矢量调制法生成六路SVPWM信号,从而实现无刷直流电机的正弦波驱动.实验结果表明采用空间矢量脉宽调制法,可以实现正弦波驱动无刷直流电机的平稳运行. 相似文献
14.
A multi-objective controller synthesis problem is considered in which an output is to be regulated approximately by assuring a bound on the steady-state peak amplification in response to an infinite-energy disturbance, while also guaranteeing a desired level of performance measured in terms of the worst-case energy gain from a finite-energy input to a performance output. Relying on a characterization of the controllers with which almost asymptotic regulation is accomplished, the problem of guaranteeing the desired level of performance is reduced to solving a system of linear matrix inequalities subject to a set of linear equality constraints. Based on the solution of this system, a procedure is outlined for the construction of a suitable controller whose order is equal to the order of the plant plus the order of the exogenous system. 相似文献
15.
以Microchip公司的dsPIC数字信号控制器dsPIC30F6010设计了交流感应电机磁场定向控制系统,介绍了磁场定向控制系统结构及基本算法,给出了磁场定向控制结构图。针对设计的几个主要部分,详细说明了dsPIC数字信号控制器结构特点及其在所设计的系统中的应用,并给出系统控制流程图的设计。 相似文献
16.
提出一个基于FP6A技术的视频捕捉处理系统的设计方案以及视频信息的捕捉、存储、显示和发送的实现方法。采用FPGA芯片EP1K30TC144,构成视频图像信息捕捉的硬件系统,利用MAX+PLUS Ⅱ开发工具,设计并实现了系统软件。具有灵活、实用和可扩展等特点。 相似文献
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18.
An obnoxious facility is to be located inside a polygonal region of the plane, maximizing the sum of the k smallest weighted Euclidean distances to n given points, each protected by some polygonal forbidden region. For the unweighted case and k fixed an O(n2logn) time algorithm is presented. For the weighted case a thorough study of the relevant structure of the multiplicatively weighted order-k-Voronoi diagram leads to the design of an O(kn3+n3logn) time algorithm for finding an optimal solution to the anti-t-centrum problem for every t=1,…,k, simultaneously. 相似文献
19.
In this paper, two delayed SEIR epidemic models with continuous and impulsive vaccination and saturating incidence are investigated. The dynamical behaviors of the disease are analyzed. For continuous vaccination, we obtain a basic reproductive number R1 and prove that if R1≤1 then the disease-free equilibrium is globally attractive and if R1>1 then the disease is permanent by using the Lyapunov functional method. For impulsive vaccination, we obtain two thresholds R∗ and R∗ and prove that if R∗<1 then the disease-free periodic solution is globally attractive and if R∗>1 then the disease is permanent by using the comparison theorem of impulsive differential equation and the Lyapunov functional method. Lastly, we compared the effects of two vaccination strategies. 相似文献
20.
Anders Wik 《Cryptologia》2016,40(3):215-220
All machines of type Enigma Z30, a model for encryption of numbers, were thought to have been destroyed. Three of these have been found in Stockholm. They were bought for commercial use around 1930. The machines and the background are described. 相似文献