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961.
虽然透博梅卡公司现在每年销售发动机超过650台,但它们却认为已经到了研制替换轴功率为450~670千瓦级发动机的时候了. 相似文献
962.
963.
T. Van Doorsselaere I. Arregui J. Andries M. Goossens S. Poedts 《Space Science Reviews》2005,121(1-4):79-89
We will discuss the observed, heavily damped transversal oscillations of coronal loops. These oscillations are often modeled
as transversal kink oscillations in a cylinder. Several features are added to the classical cylindrical model. In our models
we include loop curvature, longitudinal density stratification, and highly inhomogeneous radial density profiles.
In this paper, we will first give an overview of recently obtained results, both analytically and numerically. After that,
we shed a light on the computational aspects of the modeling process. In particular, we will focus on the parallellization
of the numerical codes. 相似文献
964.
Ground penetrating radar VIY-2 总被引:2,自引:0,他引:2
Prokhorenko V.P. Ivashchuk V.E. Korsun S.V. 《Aerospace and Electronic Systems Magazine, IEEE》2005,20(7):16-18
VIY-2 ground penetrating radar (GPR) with unique sounding possibilities and use simplicity is presented at this paper. VIY-2 GPR combines all units (synchronizer, transmitting and receiving modules, powering, and antenna system) into single case. The VIY-2 GPR communicates with computer via standard interface RS232 or USB1.0. Technical solutions utilized by the VIY-2 GPR reduce deployment time and simplify surveying process. The VIY-2 GPR design features and its components interaction are considered at this paper. Some field results are also presented here. The VIY-2 GPR design concept allows reducing the data acquisition time,, optimizing the time-varying gain control function, applying depth-stacking dependence, controlling the surveying window position and interference reducing by pulse repetition frequency randomizing. 相似文献
965.
We review observations from Voyager 2 of CIRs and merged CIRs in the outer heliosphere. The rather simple characteristics
of the CIR-associated changes in plasma, magnetic field, and particles become more complex as observations are made at greater
and greater distances. Pickup ions from charge exchange undoubtedly play an important role in the structure, but the full
details are not yet understood.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
966.
967.
单晶铝纳米级硬度试验研究 总被引:1,自引:0,他引:1
使用纳米硬度计对单晶铝进行了纳米压痕试验,利用原子力显微镜对压痕形貌进行扫描并计算硬度值,重点观察和分析了纳米级条件下单晶铝的硬度性质,结果表明,当压痕深度小于2000nm时,单晶铝纳米硬度存在尺寸效应现象;从材料性质的角度分析了纳米硬度尺寸效应现象;探讨了纳米硬度和传统硬度本质上的区别,指出其根本原因在于不同尺度下人们对材料性质的关注点不同。 相似文献
968.
The results of research in a process of a probe rocket berthing to an asteroid are presented. Control laws were obtained as solutions of three problems, namely berthing considering transient processes in a rocket engine, fastest berthing with regard to fuel consumption and berthing in a scheduled time considering fuel consumption. A program trajectory obtained at solving of the first problem is suitable for mathematical modeling of berthing with the feedback control law and stabilization of angular motion. The solutions of the problems are reduced to simple formulas for controlling parameters calculation in the corresponding structures of control laws. The results can be applied in designing promising space vehicles intended for berthing to other space objects. 相似文献
969.
Yu. V. Klochkov A. P. Nikolaev A. A. Shubovich S. S. Marchenko 《Russian Aeronautics (Iz VUZ)》2013,56(4):327-334
In this paper, we present an algorithm for geometrically nonlinear finite element analysis of the shells of revolution. Use is made of the most proper algorithms for vector interpolation of displacements through the nodal unknowns and an efficient algorithm for obtaining the stress-strain increment relation at a step of loading. By comparing the results of analyzing a geometrically nonlinear shell of revolution obtained on the basis of the ANSYS software with the scalar interpolation of displacements with those obtained on the basis of an author-developed finite element, it has been shown that application of the FEM vector displacement interpolation leads to increasing the accuracy of the finite element solutions in analyzing the stress-strain state of the geometrically nonlinear shells. 相似文献
970.
用高纯α-Fe在GLEEBLE-1500热模拟机上率进行了热压缩试验。变形温度分别为550℃,700℃,800℃和900℃,应变速率分别为0.001s~(-1),0.01s~(-1),0.1s~(-1),1s~(-1)和10s~(-1)。对其热压缩过程中的显微结构变化及真应力-真应变曲线进行的研究结果表明,形变温度的增加和应变速率降低有利于动态再结晶的进行;对动态再结晶与Z参数关系的研究结果表明,在一定的Z参数范围内即25<1nZ<37,高纯α-Fe可以发生动态再结晶,并给出动态再结晶图。 相似文献