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RISS 인기검색어
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- 저자 : Daqing Qin (검색결과 5 건)
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Impromptu Service Discovery and Provision in Heterogeneous Assistive Environments
Daqing Zhang,Weijun Qin,Brian Y. Lim,Manli Zhu 한국과학기술원 인간친화 복지 로봇 시스템 연구센터 2008 International Journal of Assistive Robotics and Me Vol.9 No.1
Wireless hotspots are permeating the globe bringing interesting services and spontaneous connectivity to mobile users. In order to enable the elderly and disabled to be fully integrated into the society, it"s of paramount importance to build a pervasive assistive environment where assistive services can be automatically discovered and easily accessed with the device-to-hand across the physical spaces. In this paper, we propose a framework that can support impromptu service discovery and context-aware service provision with mobile devices in heterogeneous smart assistive environments. Different from the existing approaches, the framework requires no specialized hardware or software installation in mobile client devices, and it can automatically discover and select appropriate services based on the user profile and situation context, and generate personalized user interfaces according to user preference and device capability. To demonstrate the effectiveness of the framework, we prototyped a set of assistive services in public spaces like shopping malls, leveraging the OSGi-based platform accessible from any WLAN enabled mobile devices.
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Impromptu Service Discovery and Provision in Heterogeneous Assistive Environments
Daqing Zhang,Weijun Qin,Brian Y. Lim,Manli Zhu 동국대학교 정보융합기술원 2008 International Journal of Assistive Robotics and Sy Vol.9 No.1
Wireless hotspots are permeating the globe bringing interesting services and spontaneous connectivity to mobile users. In order to enable the elderly and disabled to be fully integrated into the society, it’s of paramount importance to build a pervasive assistive environment where assistive services can be automatically discovered and easily accessed with the device-tohand across the physical spaces. In this paper, we propose a framework that can support impromptu service discovery and context-aware service provision with mobile devices in heterogeneous smart assistive environments. Different from the existing approaches, the framework requires no specialized hardware or software installation in mobile client devices, and it can automatically discover and select appropriate services based on the user profile and situation context, and generate personalized user interfaces according to user preference and device capability. To demonstrate the effectiveness of the framework, we prototyped a set of assistive services in public spaces like shopping malls, leveraging the OSGi-based platform accessible from any WLAN enabled mobile devices.
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Influence of Guide Vane Setting in Pump Mode on Performance Characteristics of a Pump-Turbine
Deyou Li,Hongjie Wang,Torbjørn K. Nielsen,Ruzhi Gong,Xianzhu Wei,Daqing Qin 한국유체기계학회 2017 International journal of fluid machinery and syste Vol.10 No.2
Performance characteristics in pump mode of pump-turbines are vital for the safe and effective operation of pumped storage power plants. However, the head characteristics are different under different guide vane openings. In this paper, 3-D steady simulations were performed under 13mm, 19mm and 25mm guide vane openings. Three groups of operating points under the three GVOs were chosen based on experimental validation to investigate the influence of guide vane setting on flow patterns upstream and downstream. The results reveal that, the guide vane setting will obviously change the flow pattern downstream, which in turn influences the flow upstream. It shows a strong effect on hydraulic loss (power dissipation) in the guide and stay vanes. It is also found that the hydraulic loss mainly comes from the flow separation and vortices. In addition, in some operating conditions, the change of guide vane opening will change the flow angle at the runner inlet and outlet, which will change the Euler momentum (power input). The joint action of Euler momentum and hydraulic loss results in the change of the head characteristics.
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Analysis of vorticity dynamics for hump characteristics of a pump turbine model
Deyou Li,Ruzhi Gong,Hongjie Wang,Lei Han,Xianzhu Wei,Daqing Qin 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.8
Conventional parameters based on CFD methodology for the investigation on hump characteristics of a pump turbine cannot reflect the dynamic interaction mechanism between the runner and the fluid. This research presents a dynamic interaction mechanism of a pump turbine operating in the hump region. First, vorticity dynamic parameters were obtained based on the theory of vorticity dynamics. Second, 3-D unsteady flow simulations were performed in a full pump turbine model using the SST k-ω turbulence model, and numerical results have a good agreement with the experiments. Then, analysis was carried out to determine the relation between the vorticity dynamic parameters and hump characteristics. The results indicate that the theory of vorticity dynamics has an advantage in evaluating the dynamic performance of a pump turbine. The energy transfer between the runner and the fluid is through vorticity dynamic parameterspressure and friction terms, in which the pressure term accounts for the most. Furthermore, vortex generation mainly results from the skin friction. Combining vorticity dynamic analysis with the method of Q-criterion indicates that hump characteristics are related to the reduction of the surface normal pressure work and vortex motion on the suction surfaces close to the leading edges in the runner, and the increase of skin friction work in the stay-guide vanes.
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Influence of Guide Vane Setting in Pump Mode on Performance Characteristics of a Pump-Turbine
Li, Deyou,Wang, Hongjie,Nielsen, Torbjorn K.,Gong, Ruzhi,Wei, Xianzhu,Qin, Daqing Korean Society for Fluid machinery 2017 International journal of fluid machinery and syste Vol.10 No.2
Performance characteristics in pump mode of pump-turbines are vital for the safe and effective operation of pumped storage power plants. However, the head characteristics are different under different guide vane openings. In this paper, 3-D steady simulations were performed under 13mm, 19mm and 25mm guide vane openings. Three groups of operating points under the three GVOs were chosen based on experimental validation to investigate the influence of guide vane setting on flow patterns upstream and downstream. The results reveal that, the guide vane setting will obviously change the flow pattern downstream, which in turn influences the flow upstream. It shows a strong effect on hydraulic loss (power dissipation) in the guide and stay vanes. It is also found that the hydraulic loss mainly comes from the flow separation and vortices. In addition, in some operating conditions, the change of guide vane opening will change the flow angle at the runner inlet and outlet, which will change the Euler momentum (power input). The joint action of Euler momentum and hydraulic loss results in the change of the head characteristics.
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