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961.
探讨了离散作业型(Job shop)车间中的作业调度的分阶段模型,并根据离散作业调度的阶段性提出了基于作业状态空间的逐段式车间作业调度算法,通过对一个实际车间作业调度仿真比较,此算法运算速度比最短加工时间(SPT)和最少工作量剩余(LWR)算法快,其调度结果在实际作业车间具有可执行性。 相似文献
962.
一种新颖组合变换器拓扑研究与应用 总被引:3,自引:4,他引:3
基于电源模块并联和串联的思想,提出了一种新颖双管正激组合变换器拓扑,克服了双管正激变换器副边二极管电压应力过高,输出电压和电流脉动大,只能应用于输出中低压场合的缺点,具有副边二极管电压应力低,可靠性高,原边开关管电流应力低,输出电压和电流脉动小,磁芯元件体积小等优点,本文对该新颖组合变换器进行分析,仿真和实验,表明适合应用于输入中,高电压,输出高压,大电流场合,并成功应用于某型飞机6KVA逆变器前级变换器,各项技术指标均符合设计要求。 相似文献
963.
变化和重构是快速可重构信息系统 (RRIS)的两个核心概念 ,RRIS对变化的适应或演化能力使它优于传统信息系统。本文首先提出 RRIS的体系结构 ,然后以 RRIS框架为重点 ,讨论框架的定义、分类及设计 ,研究框架的构成、构成元素 (业务构件 )的设计及构件如何在构架的组织下协调地安插在 CORBA的软总线上 ,实现类似硬件IC的即插即用。构件在框架上即插即用的灵活机制及热点构件 (反映变化 )的灵活运用 ,提高了框架的可扩展性、可定制性 ,从而提高了 RRIS适应变化的可重构性。 相似文献
964.
M.E. Yahia R.E. Tolba W.M. Moslem 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(4):1412-1424
Super rogue ion-acoustic waves are proposed as a physical catalyst for the heavy hydrocarbon ions formation in the Titan ionosphere. We justified that analytically and numerically by probing a Titan referenced plasma system, consists of the most abundant positive ions and superthermal electrons. A solution of the nonlinear Schrödinger equation (NLSE) has provided us by the plasma (un) stable regions at altitude 900–1200 km from the Titan surface with superthermal parameter values, relative ion to electron densities, and temperature ratio variations. Our results are not only agreed with the Cassini data but also predict a chemistry independent approach for the heavy hydrocarbons’ formation conditions. 相似文献
965.
Cosmic Research - Using the Meteor M2 low-orbit satellite, the dynamics of the boundaries of the auroral oval on the nightside during the magnetic storm observed from May 27 to 29, 2017, was... 相似文献
966.
Interim results of a study on use of the tethered propellant resupply technique on the space station are summarized. The acceleration produced by a gravity-gradient-stabilized tether can predictably settle propellants and thereby simplify propellant resupply of vehicles when compared to zero-g techniques. Separation of the gas and liquid phases by settling enables performance of liquid acquisition and gas venting without special hardware in the propellant tanks and without special procedures. The primary requirement for propellant transfer is control of liquid sloshing to maintain liquid over the supply tank outlet and gas over the receiver tank vent. Ultimately, the decision to use this technique on the space station may depend upon the capability to adjust depot logistic operations to a tether. 相似文献
967.
Alam E. Kherani Matheus Mascarenhas Eurico R. De Paula Jose H. A. Sobral Fernando Bertoni 《Space Science Reviews》2005,121(1-4):253-269
We present a three-dimensional simulation of collisional-interchange-instability in the equatorial-low-latitude F region of
ionosphere. The instability is responsible for the generation of large plasma density depletion or bubble. General 3D potential
and continuity equations are derived to simulate the phenomena. To understand the linear aspect of the instability, the general
3D linear growth rate is derived using 3D potential equation. The linear growth characteristics are compared with earlier
field-aligned-integrated growth analyses. The numerical simulation of bubble in the 3D spherical polar geometry is finally
presented. Distinct evolution characteristics of bubble in 3D and 2D simulation are further discussed. 相似文献
968.
N.V. Jorjio R.A. Kovrazhkin M.M. Mogilevsky J.M. Bosqued H. Rème J.A. Sauvaud C. Béghin J.L. Rauch 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(4):141-144
The plasma diagnostic experiments on the AUREOL-3 satellite have revealed flows of low energy 0+ ions deep inside the night plasmasphere during a large substorm. Flux gradients of the 0+ ions were accompanied by enhancements of ELF electric field noise. The appearance of suprathermal ions at is interpreted within the framework of electrostatic ion-cyclotron acceleration of ionospheric ions in the diffuse auroral zone /12/ followed by a radial displacement of these ions inside the plasmasphere driven by azimuthal electric fields during substorm activity. Electrostatic oscillations observed inside the plasmasphere are apparently associated with gradient instability at the sharp boundaries of suprathermal ion flows. 相似文献
969.
The first intercontinental satellite communication link, which involved the NASA Echo I balloon, a transmitting station on the Island of Trinidad, and a receiving station at Floyd, NY, is discussed. Rome Air Development Center (RADC) experimental stations were set up using a great deal of ingenuity and makeshift equipment and on a very small budget. Much of the equipment was salvaged from unrelated systems, while some was hand-built for this project. The implementation of the system, the testing of the system using moon bounce, the first orbital launch of the Echo I balloon, and the early difficulties encountered in the project are reviewed 相似文献
970.
A pure-Cartesian formulation is presented for angle-only and angle-plus-range tracking filters. Unlike conventional angle-only filters, which use target elevation and bearing as measurements, the filter expresses the sensor measurements in Cartesian coordinates. Consequently, the filter performs equally well for any line-of-sight (LOS) geometry, even when target elevation approaches or is equal to ±90° 相似文献