This paper investigates a methodology for group coordination and cooperative control of satellites with the aim to achieve formation reconfiguration such as radius enlargement and phase angle *** proposed approach sep...
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This paper investigates a methodology for group coordination and cooperative control of satellites with the aim to achieve formation reconfiguration such as radius enlargement and phase angle *** proposed approach separates the control law into two distinct stages:planar movement control and orthogonal displacement *** in plane approach is based on a cyclic pursuit strategy,where satellite i pursues satellite i +*** phase angle adjustment,a control law that makes use of "beacon's guidance" is synthesized to maintain the circling centre *** the orthogonal direction,a linear feed back control on displacement and velocity is *** of two missions with low thrust are provided,which high light the over all effectiveness of the proposed approach.
First, the paper emulated cluster bombs' random point of fall, the radius of damage of the bombs,drew the bombs' damage range, and counted the damage effect. The final damage efficiency of cluster bombs was ca...
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First, the paper emulated cluster bombs' random point of fall, the radius of damage of the bombs,drew the bombs' damage range, and counted the damage effect. The final damage efficiency of cluster bombs was calculated and the influence from each damage factor of the cluster bombs was studied through many random experiences. The method solved the tough problem of the precise calculation of damage efficiency, which was caused by the overlapped damage size.
A new structure of B-dot probes for the rail-gun speed measurement is introduced, which combines several separate loops together. It is benefit for the digital data storage equipments to control its cost. In the past,...
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A new structure of B-dot probes for the rail-gun speed measurement is introduced, which combines several separate loops together. It is benefit for the digital data storage equipments to control its cost. In the past, each B-dot used single channel of the data recording equipment. If there were ten B-dot probes, we used ten channels for the probes to record data. However, it is no need to use so many channels. Because the core output waveforms of B-dot probes distribute in different time, several probes can be connected together to form one new probe. Extremely speaking, it is possible to use only one channel to record the data, and all the probes are combined into only one B-dot probe. The new B-dot probes' data was used to improve the current waveform measurement method with loop probes. Loop probes in the breech measure the magnetic field decided by the main current. If the current's position is fixed, the waveform of current can be easily calculated by the measured magnetic field. The armature's speed information is brought to reduce the influence of the nominal current position which is always changing. The experiment results show that it works fine to measure the current in low cost.
Sensitivity analysis on weapons and equipment is the foundation for determining the priorities of development and construction of army weapons and equipment, constitutes the important contents of system optimization. ...
Sensitivity analysis on weapons and equipment is the foundation for determining the priorities of development and construction of army weapons and equipment, constitutes the important contents of system optimization. In this paper, the applicability Sobol index method in the analysis of sensitivity of army equipment system effectiveness was explained, the model of Sobol index method theory was established, examples of sensitivity of army equipment system effectiveness was offered, and the applicability of this method was described through the comparisons of several common sensitivity indexes and the sensitivity index in Sobol index method.
Inductive energy storage systems (IES)require opening switches which are technically much more difficult to realize than closing switches. Institute of Advanced technology ( IAT ) puts forward a meat grinder with ...
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Inductive energy storage systems (IES)require opening switches which are technically much more difficult to realize than closing switches. Institute of Advanced technology ( IAT ) puts forward a meat grinder with an inductive pulse power topology called slow transfer of energy through capacitive hybrid (STRETCH). In this topology, an integrated gate-commutated thyristor (IGCT) is capable of breaking the charging currents on the order of 4 kA, and it may encounter difficulties in expanding to higher energy systems. German-French Institute of Saint Louis (ISL) has developed a high-power opening switch based on standard high-power thyristors by using their so-called inverse current commutation with semiconductor devices (ICCOS) countercurrent commutation principle. Two topologies of the STRETCH meat grinder with ICCOS are analyzed. And they are compared based on the voltage across the main switch, the current multiplication factor and other aspects by u- sing Matlab simulations. The advantages and disadvantages of the two topologies are shown through the comparisons. Therefore a more suitable topology can be chosen for realistic applications accord- ing to their performances.
In this paper, an unified information description model ("UIDM" for short) is proposed to model information from multiple sources in the Information Grid uniformly. In the UIDM: 1) An unified information des...
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A supersonic jet interaction flowfield with pressure ratios of 2.8-16.7 exhausting into subsonic and transonic crossflows (Mach 0.5-0.8) was simulated using computational fluid dynamics and compared to experimental pa...
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ISBN:
(数字)9781624102882
ISBN:
(纸本)9781624102882
A supersonic jet interaction flowfield with pressure ratios of 2.8-16.7 exhausting into subsonic and transonic crossflows (Mach 0.5-0.8) was simulated using computational fluid dynamics and compared to experimental particle image velocimetry data. Three independent studies using different Reynolds-averaged Navier-Stokes flow solvers and a variety of turbulence models were used to assess the accuracy level of the predicted downsteam flow physics of the jet interaction problem. Evaluation of the prediction of the downstream flow structure was made via comparisons of the three components of velcocity and turbulent kinetic energy. In general, the predicted jet interaction flowfield was highly sensitive to the turbulence model used, with performance of the turbulence model being dependent on the flow solver, and relatively insensitive to crossflow Mach number in the range investigated.
Superhydrophobicity on structured surfaces is frequently achieved via the maintenance of liquid-air interfaces adjacent to the trapped air pockets. These interfaces, however, are subject to instabilities due to the Ca...
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Superhydrophobicity on structured surfaces is frequently achieved via the maintenance of liquid-air interfaces adjacent to the trapped air pockets. These interfaces, however, are subject to instabilities due to the Cassie-Baxter-to-Wenzel transition and total wetting. The current work examines in situ liquid-air interfaces on a submerged surface patterned with cylindrical micropores using confocal microscopy. Both the pinned Cassie-Baxter and depinned metastable states are directly observed and measured. The metastable state dynamically evolves, leading to a transition to the Wenzel state. This process is extensively quantified under different ambient pressure conditions, and the data are in good agreement with a diffusion-based model prediction. A similarity law along with a characteristic time scale is derived which governs the lifetime of the air pockets and which can be used to predict the longevity of underwater superhydrophobicity.
We present a markerless augmented reality(AR) system based on 3D model. First, the feature of environment was extracted using SIFT operator, then the method of stratified reconstruction was used to reconstruct the 3D ...
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For the parameter estimation problem of inertial instrumentation error models, a Bayesian network is founded to fuse the calibration data and make error coefficients statistical inference in this paper. First the fund...
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