We propose a novel all-optical sampling method using nonlinear polarization rotation in a semiconductor optical amplifier. A rate-equation model capable of describing the all-optical sampling mechanism is presented in...We propose a novel all-optical sampling method using nonlinear polarization rotation in a semiconductor optical amplifier. A rate-equation model capable of describing the all-optical sampling mechanism is presented in this paper. Based on this model, we investigate the optimized operating parameters of the proposed system by simulating the output intensity of the probe light as functions of the input polarization angle, the phase induced by the polarization controller, and the ori- entation of the polarization beam splitter. The simulated results show that we can obtain a good linear slope and a large linear dynamic range,which is suitable for all-optical sampling. The operating power of the pump light can be less than lmW. The presented all-optical sampling method can potentially operate at a sampling rate up to hundreds GS/s and needs low optical power.展开更多
Preservation technology of light control has received the widespread atten- tion for its safety, green, environmental-protection, high efficiency. It has become the hotspot in the area of postharvest vegetables preser...Preservation technology of light control has received the widespread atten- tion for its safety, green, environmental-protection, high efficiency. It has become the hotspot in the area of postharvest vegetables preservation. It could mainly be divid- ed into three categories： LED preservation, UV preservation and radiation preserva- tion. This paper systematically reviewed the mechanisms of different preservation technology of light control, summarized the research progress of light-controlled tech- nology in the physiological characteristics regulation, maintenance of nutritional quali- ty and microbial control of postharvest vegetables at home and aborad, and prospected the further studies on preservation technology for postharvest vegetables.展开更多
The urgency of increasing energy efficiency in new building design and retrofits has pushed lighting simulation to play a central role in sustainable lighting design. The shape of the building and its orientation, the...The urgency of increasing energy efficiency in new building design and retrofits has pushed lighting simulation to play a central role in sustainable lighting design. The shape of the building and its orientation, the reflectances of building surfaces and glazed areas are important parameters in the daylighting design of buildings. Glazing systems can cut energy consumption and associated pollution sources, reduce peak demand, enhance daylighting performance and improve occupant comfort. This paper presents the results of a numerical and experimental comparison between the performances of an office building with and without external sunscreens. The aim was to analyse the illuminance distribution and some investigations have also been made with regards to the effect on daylight in rooms when sunscreens are used. The experimental results were obtained using an office building scale model and sky simulator. The numerical results were obtained through radiance, the ray-tracing program, to accurately predict the light levels and produce photo realistic images of the architectural space in all sky conditions： Illuminance values were obtained respectively through reference point measurements. The daylighting performances of the office building model with and without the sunscreens have been compared and analysed.展开更多
In order to investigate the characteristics of re-oxidation of residual coal in goafs in close coal seam mining,scanning electron microscope and infrared spectrometer are used to study the changes of coal microstructu...In order to investigate the characteristics of re-oxidation of residual coal in goafs in close coal seam mining,scanning electron microscope and infrared spectrometer are used to study the changes of coal microstructure and chemical reaction of functional groups of eight coal samples at different ranks.Result shows that after initial oxidation,the surface morphology of pore are different,and the porosity of coal is increased and the oxygen adsorption capacity of coal is improved.The change of coal molecular structure and presence of a large amount of active oxygen-containing functional groups lead to increasing tendency of coal to further oxidation.In addition,the higher lever of the initial oxidation is,the easier the re-oxidation occurs.展开更多
Improving daylighting strategy is a mandatory step to achieve visual enjoyment and energy saving in buildings. Psycho, physiological effects and energy performance have to be investigated in order to define a range of...Improving daylighting strategy is a mandatory step to achieve visual enjoyment and energy saving in buildings. Psycho, physiological effects and energy performance have to be investigated in order to define a range of different daylighting strategies, thanks to daylighting devices and climate based daylight modeling. Daylighting optimization ensures indoor healthier rooms, reduces electric light consumption and cuts the risk of glare. The best way to achieve these targets is to define users lighting needs, based on visual targets and to draw up some green measures to reduce electricity demands. Involving new climate-based daylight modeling metrics aims at defining proper illumination targets, in order to drastically reduce electrical lights, as well as reducing thermal loads deriving from cooling and HVAC （heating, ventilation and air conditioning） systems.展开更多
Simulation based structural reliability analysis suffers from a heavy computational burden, as each sample needs to be evaluated on the performance function, where structural analysis is performed. To alleviate the co...Simulation based structural reliability analysis suffers from a heavy computational burden, as each sample needs to be evaluated on the performance function, where structural analysis is performed. To alleviate the computational burden, related research focuses mainly on reduction of samples and application of surrogate model, which substitutes the performance function. However,the reduction of samples is achieved commonly at the expense of loss of robustness, and the construction of surrogate model is computationally expensive. In view of this, this paper presents a robust and efficient method in the same direction. The present method uses radial-based importance sampling (RBIS) to reduce samples without loss of robustness. Importantly, Kriging is fully used to efficiently implement RBIS. It not only serves as a surrogate to classify samples as we all know, but also guides the procedure to determine the optimal radius, with which RBIS would reduce samples to the highest degree. When used as a surrogate, Kriging is established through active learning, where the previously evaluated points to determine the optimal radius are reused. The robustness and efficiency of the present method are validated by five representative examples, where the present method is compared mainly with two fundamental reliability methods based on active learning Kriging.展开更多
文摘We propose a novel all-optical sampling method using nonlinear polarization rotation in a semiconductor optical amplifier. A rate-equation model capable of describing the all-optical sampling mechanism is presented in this paper. Based on this model, we investigate the optimized operating parameters of the proposed system by simulating the output intensity of the probe light as functions of the input polarization angle, the phase induced by the polarization controller, and the ori- entation of the polarization beam splitter. The simulated results show that we can obtain a good linear slope and a large linear dynamic range,which is suitable for all-optical sampling. The operating power of the pump light can be less than lmW. The presented all-optical sampling method can potentially operate at a sampling rate up to hundreds GS/s and needs low optical power.
基金Supported by the National Key Research and Development Program of China(2016YFD0400901)the China Agricultural Research System for Staple Vegetables(CARS-25)+2 种基金the National Natural Science Foundation of China(31401536)the Research and Demonstration of Ecological and High-efficient Production Technology for Horticultural Plants in the Uncultivated Area of Northwest China(201203095)the Youth Foundation of Beijing Academy of Agriculture and Forestry Sciences(201709)~~
文摘Preservation technology of light control has received the widespread atten- tion for its safety, green, environmental-protection, high efficiency. It has become the hotspot in the area of postharvest vegetables preservation. It could mainly be divid- ed into three categories： LED preservation, UV preservation and radiation preserva- tion. This paper systematically reviewed the mechanisms of different preservation technology of light control, summarized the research progress of light-controlled tech- nology in the physiological characteristics regulation, maintenance of nutritional quali- ty and microbial control of postharvest vegetables at home and aborad, and prospected the further studies on preservation technology for postharvest vegetables.
文摘The urgency of increasing energy efficiency in new building design and retrofits has pushed lighting simulation to play a central role in sustainable lighting design. The shape of the building and its orientation, the reflectances of building surfaces and glazed areas are important parameters in the daylighting design of buildings. Glazing systems can cut energy consumption and associated pollution sources, reduce peak demand, enhance daylighting performance and improve occupant comfort. This paper presents the results of a numerical and experimental comparison between the performances of an office building with and without external sunscreens. The aim was to analyse the illuminance distribution and some investigations have also been made with regards to the effect on daylight in rooms when sunscreens are used. The experimental results were obtained using an office building scale model and sky simulator. The numerical results were obtained through radiance, the ray-tracing program, to accurately predict the light levels and produce photo realistic images of the architectural space in all sky conditions： Illuminance values were obtained respectively through reference point measurements. The daylighting performances of the office building model with and without the sunscreens have been compared and analysed.
基金the National Key Foundation for Exploring Scientific Instruments of China(No.2012YQ24012705)the National Natural Science Foundation of China(No.51174113)+2 种基金the special fund for Scientific Research Institutes of China(Nos.2013EG122192 and 2014EG122293)CCTEG Innovation Foundation of China(No. 2014MS030)Shenhua Innovation Foundation of China(No. SHGF-13-07)
文摘In order to investigate the characteristics of re-oxidation of residual coal in goafs in close coal seam mining,scanning electron microscope and infrared spectrometer are used to study the changes of coal microstructure and chemical reaction of functional groups of eight coal samples at different ranks.Result shows that after initial oxidation,the surface morphology of pore are different,and the porosity of coal is increased and the oxygen adsorption capacity of coal is improved.The change of coal molecular structure and presence of a large amount of active oxygen-containing functional groups lead to increasing tendency of coal to further oxidation.In addition,the higher lever of the initial oxidation is,the easier the re-oxidation occurs.
文摘Improving daylighting strategy is a mandatory step to achieve visual enjoyment and energy saving in buildings. Psycho, physiological effects and energy performance have to be investigated in order to define a range of different daylighting strategies, thanks to daylighting devices and climate based daylight modeling. Daylighting optimization ensures indoor healthier rooms, reduces electric light consumption and cuts the risk of glare. The best way to achieve these targets is to define users lighting needs, based on visual targets and to draw up some green measures to reduce electricity demands. Involving new climate-based daylight modeling metrics aims at defining proper illumination targets, in order to drastically reduce electrical lights, as well as reducing thermal loads deriving from cooling and HVAC （heating, ventilation and air conditioning） systems.
基金supported by the National Natural Science Foundation of China (Grant No. 11421091)the Fundamental Research Funds for the Central Universities (Grant No. HIT.MKSTISP.2016 09)
文摘Simulation based structural reliability analysis suffers from a heavy computational burden, as each sample needs to be evaluated on the performance function, where structural analysis is performed. To alleviate the computational burden, related research focuses mainly on reduction of samples and application of surrogate model, which substitutes the performance function. However,the reduction of samples is achieved commonly at the expense of loss of robustness, and the construction of surrogate model is computationally expensive. In view of this, this paper presents a robust and efficient method in the same direction. The present method uses radial-based importance sampling (RBIS) to reduce samples without loss of robustness. Importantly, Kriging is fully used to efficiently implement RBIS. It not only serves as a surrogate to classify samples as we all know, but also guides the procedure to determine the optimal radius, with which RBIS would reduce samples to the highest degree. When used as a surrogate, Kriging is established through active learning, where the previously evaluated points to determine the optimal radius are reused. The robustness and efficiency of the present method are validated by five representative examples, where the present method is compared mainly with two fundamental reliability methods based on active learning Kriging.
