A super-resolution reconstruction algorithm is proposed. The algorithm is based on the idea of the sparse representation of signals, by using the fact that the sparsest representation of a sig- nal is unique as the co...A super-resolution reconstruction algorithm is proposed. The algorithm is based on the idea of the sparse representation of signals, by using the fact that the sparsest representation of a sig- nal is unique as the constraint of the patched-based reconstruction, and compensating residual errors of the reconstruction results both locally and globally to solve the distortion problem in patch-based reconstruction algorithms. Three reconstruction algorithms are compared. The results show that the images reconstructed with the new algorithm have the best quality.展开更多
This paper presents a dynamic knowledge graph approach that offers a reusable,interoperable,and extensible framework for modelling power systems.Domain ontologies have been developed to support a linked data represent...This paper presents a dynamic knowledge graph approach that offers a reusable,interoperable,and extensible framework for modelling power systems.Domain ontologies have been developed to support a linked data representation of infrastructure data,socio-demographic data,areal attributes like demand,and models describing power systems.The knowledge graph links the data with a hierarchical representation of administrative regions,supporting geospatial queries to retrieve information about the population within the vicinity of a power plant,the number of power plants,total generation capacity,and demand within specific areas.Computational agents were developed to operate on the knowledge graph.The agents performed tasks including data uploading,updating,retrieval,processing,model construction and scenario analysis.A derived information framework was used to track the provenance of information calculated by agents involved in each scenario.The knowledge graph was populated with data describing the UK power system.Two alternative models of the transmission grid with different levels of structural resolution were instantiated,providing the foundation for the power system simulation and optimisation tasks performed by the agents.The application of the dynamic knowledge graph was demonstrated via a case study that investigates clean energy transition trajectories based on the deployment of Small Modular Reactors in the UK.展开更多
To make full use of the photocathode material and improve its quantum efficiency lifetime, it can be necessary to operate the laser away from the cathode center in photoinjectors. In RF guns, the off-axis emitted beam...To make full use of the photocathode material and improve its quantum efficiency lifetime, it can be necessary to operate the laser away from the cathode center in photoinjectors. In RF guns, the off-axis emitted beam will see a time-dependent RF effect, which would generate a significant growth in transverse emittance. It has been demonstrated that such an emittance growth can be almost completely compensated by orienting the beam on a proper orbit in the downstream RF cavities along the injector [1]. In this paper we analyze in detail the simulation techniques used in reference [1] and the issues associated with them. The optimization of photoinjector systems involving off-axis beams is a challenging problem. To solve this problem, one needs advanced simulation tools including both genetic algorithms and an efficient algorithm for 3D space charge. In this paper, we report on simulation studies where the two codes ASTRA and IMPACT-T are used jointly to overcome these challenges, in order to optimize a system designed to compensate for the emittance growth in a beam emitted off axis.展开更多
Effects of spontaneous condensation of moist air on the shock wave dynamics around butterfly valves in transonic flows are investigated by experimental and numerical simulations.Two symmetric valve disk shapes namely-...Effects of spontaneous condensation of moist air on the shock wave dynamics around butterfly valves in transonic flows are investigated by experimental and numerical simulations.Two symmetric valve disk shapes namely-a flat rectangular plate and a mid-plane cross-section of a prototype butterfly valve have been studied in the present research.Results showed that in case with spontaneous condensation,the root mean square of pressure oscillation(induced by shock dynamics)is reduced significantly with those without condensation for both shapes of the valves.Moreover,local aerodynamic moments were reduced in case with condensation which is considered to be beneficial in torque requirement in case of on/off applications of valves as flow control devices.However,total pressure loss was increased with spontaneous condensation in both the valves.Furthermore,the disk shape of a prototype butterfly valve showed better aerodynamic performances compared to flat rectangular plate profile in respect of total pressure loss and vortex shedding frequency in the wake region.展开更多
分别以高分子三嵌段共聚物P123(PEO20-PPO70-PEO20)和F127(PEO106-PPO70-PEO106)为模板剂,通过高温水热法制备了具有超低介电常数的规则介孔氧化硅材料(OMSs).当合成温度达到200℃时,得到的产物仍可保持规则的介孔结构.X射线衍射和氮气...分别以高分子三嵌段共聚物P123(PEO20-PPO70-PEO20)和F127(PEO106-PPO70-PEO106)为模板剂,通过高温水热法制备了具有超低介电常数的规则介孔氧化硅材料(OMSs).当合成温度达到200℃时,得到的产物仍可保持规则的介孔结构.X射线衍射和氮气吸附结果表明,OMSs系列材料具有规则的二维六方或体心立方介孔结构、大的比表面积和孔容及均一的孔径分布.29Si MAS NMR分析表明,OMSs与低温(100℃)合成产物相比具有更高的骨架缩合度,从而具有优异的水热稳定性.由于具有大的孔容和高的骨架缩合度,OMSs表现出了超低的介电常数.以P123为模板剂,200℃下合成的OMS的介电常数可达1.31.OMSs作为一类稳定的超低介电常数材料,对于绝缘材料的发展具有潜在的应用价值.展开更多
基金Supported by the Basic Research Foundation of Beijing Institute of Technology(3050012211105)
文摘A super-resolution reconstruction algorithm is proposed. The algorithm is based on the idea of the sparse representation of signals, by using the fact that the sparsest representation of a sig- nal is unique as the constraint of the patched-based reconstruction, and compensating residual errors of the reconstruction results both locally and globally to solve the distortion problem in patch-based reconstruction algorithms. Three reconstruction algorithms are compared. The results show that the images reconstructed with the new algorithm have the best quality.
基金supported by the National Research Foundation,Prime Minister’s Office,Singapore under its Campus for Research Excellence and Technological Enterprise(CREATE)programme.Part of this work was also supported by Towards Turing 2.0 under the EPSRC Grant EP/W037211/1.
文摘This paper presents a dynamic knowledge graph approach that offers a reusable,interoperable,and extensible framework for modelling power systems.Domain ontologies have been developed to support a linked data representation of infrastructure data,socio-demographic data,areal attributes like demand,and models describing power systems.The knowledge graph links the data with a hierarchical representation of administrative regions,supporting geospatial queries to retrieve information about the population within the vicinity of a power plant,the number of power plants,total generation capacity,and demand within specific areas.Computational agents were developed to operate on the knowledge graph.The agents performed tasks including data uploading,updating,retrieval,processing,model construction and scenario analysis.A derived information framework was used to track the provenance of information calculated by agents involved in each scenario.The knowledge graph was populated with data describing the UK power system.Two alternative models of the transmission grid with different levels of structural resolution were instantiated,providing the foundation for the power system simulation and optimisation tasks performed by the agents.The application of the dynamic knowledge graph was demonstrated via a case study that investigates clean energy transition trajectories based on the deployment of Small Modular Reactors in the UK.
基金Supported by National Nature Science Foundation of China(11375199)Chinese Scholarship Council
文摘To make full use of the photocathode material and improve its quantum efficiency lifetime, it can be necessary to operate the laser away from the cathode center in photoinjectors. In RF guns, the off-axis emitted beam will see a time-dependent RF effect, which would generate a significant growth in transverse emittance. It has been demonstrated that such an emittance growth can be almost completely compensated by orienting the beam on a proper orbit in the downstream RF cavities along the injector [1]. In this paper we analyze in detail the simulation techniques used in reference [1] and the issues associated with them. The optimization of photoinjector systems involving off-axis beams is a challenging problem. To solve this problem, one needs advanced simulation tools including both genetic algorithms and an efficient algorithm for 3D space charge. In this paper, we report on simulation studies where the two codes ASTRA and IMPACT-T are used jointly to overcome these challenges, in order to optimize a system designed to compensate for the emittance growth in a beam emitted off axis.
文摘Effects of spontaneous condensation of moist air on the shock wave dynamics around butterfly valves in transonic flows are investigated by experimental and numerical simulations.Two symmetric valve disk shapes namely-a flat rectangular plate and a mid-plane cross-section of a prototype butterfly valve have been studied in the present research.Results showed that in case with spontaneous condensation,the root mean square of pressure oscillation(induced by shock dynamics)is reduced significantly with those without condensation for both shapes of the valves.Moreover,local aerodynamic moments were reduced in case with condensation which is considered to be beneficial in torque requirement in case of on/off applications of valves as flow control devices.However,total pressure loss was increased with spontaneous condensation in both the valves.Furthermore,the disk shape of a prototype butterfly valve showed better aerodynamic performances compared to flat rectangular plate profile in respect of total pressure loss and vortex shedding frequency in the wake region.
文摘分别以高分子三嵌段共聚物P123(PEO20-PPO70-PEO20)和F127(PEO106-PPO70-PEO106)为模板剂,通过高温水热法制备了具有超低介电常数的规则介孔氧化硅材料(OMSs).当合成温度达到200℃时,得到的产物仍可保持规则的介孔结构.X射线衍射和氮气吸附结果表明,OMSs系列材料具有规则的二维六方或体心立方介孔结构、大的比表面积和孔容及均一的孔径分布.29Si MAS NMR分析表明,OMSs与低温(100℃)合成产物相比具有更高的骨架缩合度,从而具有优异的水热稳定性.由于具有大的孔容和高的骨架缩合度,OMSs表现出了超低的介电常数.以P123为模板剂,200℃下合成的OMS的介电常数可达1.31.OMSs作为一类稳定的超低介电常数材料,对于绝缘材料的发展具有潜在的应用价值.
