Search

In order to strengthen the detection and monitoring of space targets, especially non-cooperative targets, more and more attention has been paid to the characteristics of space targets. The position, velocity, attitude, angular velocity and material complex refractive index of space target were inversely estimated by unscented Kalman filter (UKF). The observation angle, photometric and degree of polarization data were used as the observation values to estimate the state of the target. Based on the position and velocity kinematics model and the attitude and angular velocity dynamic model, the time evolution of the five states was completed, and the joint estimation of the five state parameters was realized. The simulation results show that setting reasonable initial state value, state equation and measurement equation noise, the errors of five state parameters can converge reasonably, and UKF can better predict the five characteristic parameters of space targets. At the same time, it is also verified that the observation angle, luminosity and polarization data can be used to retrieve the five indirect observation characteristic information of space moving targets. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Special Oil & Gas Reservoirs is the property of Special Oil & Gas Reservoirs Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The nonlinear state equations describing the coupling between control rod drop and fluid flow were proposed to solve the problem of control rod drop in nuclear reactors. The state equations have a uniform format for different fluid states in the process of control rod drop, which can conveniently deal with the problem for different working conditions. To efficiently analyze the falling process, accurately capture the sudden change of flow state and ensure the numerical stability of time integral, an adaptive time step-based symplecticity-preserving algorithm was proposed. Numerical examples show that, the proposed numerical model can accurately calculate the key data such as the displacement, the velocity, the acceleration and the falling time of the control rod in the falling process with a large time step, and the calculated results are in good agreement with those obtained the by the commercial software. [ABSTRACT FROM AUTHOR]

In order to efficiently recover and utilize the produced fluid from high-CO2 gas wells in Huangqiao, thermodynamic state equation (PRSV state equation and WS mixing rule) and flash evaporation calculation theory were adopted for phase state calculation of the produced fluid from high-CO2 gas wells in Huangqiao, which revealed the phase diagram feature of the high-CO2 well flow in Huangqiao and the influence of CO2 on the phase state of oil and gas hydrocarbon system. Specifically, the gas-liquid two-phase area, which is on the p-T phase diagram of oil and gas hydrocarbon system containing CO2, decreases significantly with the increase of CO2 mole fraction. According to the phase characteristics of the produced fluid, the surface treatment process of single well was established, and the operating parameters of key equipment (cyclone separator and CO2 compressor) in the produced fluid treatment process were analyzed, concluding that all the currently selected operating parameters were in the reliable working area (single phase gas area) of cyclone separator. There was no liquid phase precipitation in the full working pressure and temperature range of CO2 compressor. The established gathering and transportation process flow and operating parameters of equipment in Huangqiao high-CO2 single wells have been verified to be reasonable, and on this basis, free water and liquid crude oil can be effectively removed from the high-CO2 single well flow in this area. The process flow and operating parameters of equipment can be promoted and used in similar condition blocks of this area.

Copyright of Natural Gas & Oil is the property of Editorial Department of Natural Gas & Oil and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The 3D generalized hydrodynamics of soft-matter quasicrystals was investigated, and the governing equations for observed and possibly observed soft-matter quasicrystals were derived. The solving procedure for the equations was discussed briefly. Some results obtained reveal the gigantic dissimilarities between soft-matter quasicrystals and solid ones. [ABSTRACT FROM AUTHOR]

The equation systems of generalized hydrodynamics for soft-matter quasicrystals were established based on the Langevin equation, with the derivation method of Poisson bracket. The derivation was done with reference to the work on solid quasicrystals, for which there were only 2 kinds of elementary excitations： phonons and phasons. However, the generalized hydrodynamics for soft-matter quasicrystals was essentially different from that for solid ones. In the generalized hydrodynamics for solid quasicrystals the effects of solid viscosity and the interaction among viscosity, phonons and phasons were considered, without the need of state equations. Nevertheless, the fluid phonon and the interaction among fluid phonons, phonons and phasons in soft-matter quasicrystals were to be considered, where 3 kinds of elementary excitations, i.e. phonons, phasons and fluid phonons meant state equations were indispensable. This difficult problem was solved with the present method. The results show the correctness and efficiency of the theoretical analysis. [ABSTRACT FROM AUTHOR]

Copyright of Hydrographic Surveying & Charting / Haiyang Cehui is the property of Hydrographic Surveying & Charting Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

While satisfying the precondition of the pump efficiency and head, the studies of cavitation performance of mixed-flow pump are carried out based on the cavitation model with the barotropic fluid state equation in order to prevent cavitations occurring as far as possible. The experimental results show that the mixed-flow pump with five blades, designed by velocity coefficient method, is not reasonable due to higher critical net positive suction head under design condition. Consequently, inlet edge shape and thickness of the pump impeller blades, and the variation of blades thickness along flowing direction are optimized using the pump efficiency and head as the objective functions after increasing the pump impeller blade number to seven. Cavitation performances among three types of mixed-flow pump with different blade structures are compared and analyzed. Some useful conclusions are conducted. The critical net positive suction head can be greatly reduced by extending the blade inlet toward the pump inlet properly, attenuating the blade inlet edge and optimizing the blade thickness. The optimized pump efficiency and head are 90. 857% and 163. 86 m respectively, and the critical net positive suction head reaches 28. 64 m which is relatively reduced by 45% compared with that of the original pump with 5 blades. The effective improvement of the cavitation performance in the design condition provides helpful directions for further design and optimization of the mixed-flow pump. [ABSTRACT FROM AUTHOR]

As automatic height adjusting of the shearer was achieved by electro-hydraulic proportional servo control, established a height-adjustment cylinder model of the shearer, and deduced state space equation of the shearer height adjusting system, then designed an automatic height adjusting controller, in the controller authors adopted the controller sliding-mode variable structure control strategy, including the sliding function design and sliding control rule analysis. Finally, based on the state equation and the controlling function, authors simulated the shearer height adjusting controller, the results show that with the sliding mode variable structure control strategy, the automatic height adjusting become fast and stable. [ABSTRACT FROM AUTHOR]