以杏树为试材，为了解杏树冠层内透光率随树龄和叶面积指数的变化，采用LP-80型冠层分析仪测定了光合有效辐射PAR（Photosynthetically Active Radiation）在不同树龄杏树冠层三维空间上的分布情况，研究了杏树冠层内透光率随树龄（2-6...以杏树为试材，为了解杏树冠层内透光率随树龄和叶面积指数的变化，采用LP-80型冠层分析仪测定了光合有效辐射PAR（Photosynthetically Active Radiation）在不同树龄杏树冠层三维空间上的分布情况，研究了杏树冠层内透光率随树龄（2-6a）和叶面积指数的变化。结果表明，杏树冠层内部平均PAR的垂直分布具有随着向下累计叶面积指数的增加而递减的趋势，在冠层中上部，透光率较高，PAR递减很明显，冠层下部则维持较低水平，变化不大，在相同的天气和时间条件下不同树龄冠层内PAR同一相对高度的透光率有随树龄增加而递减的趋势，但在不同时刻不同天气条件下，即使同一棵树相同高度同一方位冠层内也具有不同的消光系数，影响杏树冠内光分布的因素是多样的，它们之间存在着复杂的关系；2～6年生杏树冠层中部的全天平均透光率分别为49．5％、30．0％、27．5％、13．4％和7．8％，冠层下部的平均透光率分别为29．1％、12．1％、10．9％、6．4％和5．9％；杏树冠层叶面积指数LAI（kaf Area Index）与透光率呈极显著指数相关关系，其表达式为Y=131．39e^-0．8963X（R^2=0．907^＊＊）；试验结果也可为果树冠层内PAR三维空间分布的模拟研究及冠层结构的优化提供试验方法和理论验证上的参考。展开更多
Recently, semiconductor quantum dot (QD) sensitized solar cells (QDSSCs) are expected to achieve higher conversion efficiency because of the large light absorption coefficient and multiple exciton generation in QDs. T...Recently, semiconductor quantum dot (QD) sensitized solar cells (QDSSCs) are expected to achieve higher conversion efficiency because of the large light absorption coefficient and multiple exciton generation in QDs. The morphology of TiO2 electrode is one of the most important factors in QDSSCs. Inverse opal (IO) TiO2 electrode, which has periodic mesoporous structure, is useful for QDSSCs because of better penetration of electrolyte than conventional nanoparticulate TiO2 electrode. In addition, the ordered three dimensional structure of IO-TiO2 would be better for electron transport. We have found that open circuit voltage Voc of QDSSCs with IO-TiO2 electrodes was much higher (0.2 V) than that with nanoparticulate TiO2 electrodes. But short circuit current density Jsc was lower in the case of IO-TiO2 electrodes because of the smaller surface area of IO-TiO2. In this study, for increasing surface area of IO-TiO2, we applied TiCl4 post treatment on IO-TiO2 and investigated the effect of the post treatment on photovoltaic properties of CdSe QD sensitized IO-TiO2 solar cells. It was found that Jsc could be enhanced due to TiCl4 post treatment, but decreased again for more than one cycle treatment, which indicates excess post treatment may lead to worse penetration of electrolyte. Our results indicate that the appropriate post treatment can improve the energy conversion efficiency of the QDSSCs.展开更多
WiFi fingerprinting is the method of recording WiFi signal strength from access points （AP） along with the positions at which they were recorded, and later matching those to new mea- surements for indoor positioning...WiFi fingerprinting is the method of recording WiFi signal strength from access points （AP） along with the positions at which they were recorded, and later matching those to new mea- surements for indoor positioning. Inertial positioning utilizes the accelerometer and gyroscopes for pedestrian positioning. However, both methods have their limitations, such as the WiFi fluctuations and the accumulative error of inertial sensors. Usually, the filtering method is used for integrating the two approaches to achieve better location accuracy. In the real environments, especially in the indoor field, the APs could be sparse and short range. To overcome the limitations, a novel particle filter approach based on Rao Blackwellized particle filter （RBPF） is presented in this paper. The indoor environment is divided into several local maps, which are assumed to be independent of each other. The local areas are estimated by the local particle filter, whereas the global areas are com- bined by the global particle filter. The algorithm has been investigated by real field trials using a WiFi tablet on hand with an inertial sensor on foot. It could be concluded that the proposed method reduces the complexity of the positioning algorithm obviously, as well as offers a significant improvement in position accuracy compared to other conventional algorithms, allowing indoor positioning error below 1.2 m.展开更多
We present the microbial green synthesis of silver nanoparticles （hiPs） by Streptomyces ghanaensis VITHM1 strain （MTCC No. 12465）. The secondary metabolites in the cell free supernatant of this bacterium when incu...We present the microbial green synthesis of silver nanoparticles （hiPs） by Streptomyces ghanaensis VITHM1 strain （MTCC No. 12465）. The secondary metabolites in the cell free supernatant of this bacterium when incubated with 1 mmol/L AgNO3, mediated the biological synthesis of AgNPs. The synthesized AgNPs were characterized by UV-visible spectrum, X-ray diffrac- tion （XRD）, atomic force microscope, scanning electron microscopy equipped with energy dispersive spectroscopy, transmission electron microscopy, FT-IR spectroscopy, dynamic light scattering and zeta potential. They were highly stable and, spherical in shape with the average size of 30-50 nm. The secondary metabolites involved in the formation of AgNPs were identified gas chromatographymass spectrography. The 3D structure of the unit cell of the synthesized AgNPs was determined using XRD data base. The synthesized AgNPs exhibited significant antibacterial activity against tested bacterial pathogens, and did not show haemolysis on human red blood cells. This green synthesis could provide a new platform to explore and use AgNPs as antibacterial therapeutic agents.展开更多
文摘以杏树为试材，为了解杏树冠层内透光率随树龄和叶面积指数的变化，采用LP-80型冠层分析仪测定了光合有效辐射PAR（Photosynthetically Active Radiation）在不同树龄杏树冠层三维空间上的分布情况，研究了杏树冠层内透光率随树龄（2-6a）和叶面积指数的变化。结果表明，杏树冠层内部平均PAR的垂直分布具有随着向下累计叶面积指数的增加而递减的趋势，在冠层中上部，透光率较高，PAR递减很明显，冠层下部则维持较低水平，变化不大，在相同的天气和时间条件下不同树龄冠层内PAR同一相对高度的透光率有随树龄增加而递减的趋势，但在不同时刻不同天气条件下，即使同一棵树相同高度同一方位冠层内也具有不同的消光系数，影响杏树冠内光分布的因素是多样的，它们之间存在着复杂的关系；2～6年生杏树冠层中部的全天平均透光率分别为49．5％、30．0％、27．5％、13．4％和7．8％，冠层下部的平均透光率分别为29．1％、12．1％、10．9％、6．4％和5．9％；杏树冠层叶面积指数LAI（kaf Area Index）与透光率呈极显著指数相关关系，其表达式为Y=131．39e^-0．8963X（R^2=0．907^＊＊）；试验结果也可为果树冠层内PAR三维空间分布的模拟研究及冠层结构的优化提供试验方法和理论验证上的参考。
文摘Recently, semiconductor quantum dot (QD) sensitized solar cells (QDSSCs) are expected to achieve higher conversion efficiency because of the large light absorption coefficient and multiple exciton generation in QDs. The morphology of TiO2 electrode is one of the most important factors in QDSSCs. Inverse opal (IO) TiO2 electrode, which has periodic mesoporous structure, is useful for QDSSCs because of better penetration of electrolyte than conventional nanoparticulate TiO2 electrode. In addition, the ordered three dimensional structure of IO-TiO2 would be better for electron transport. We have found that open circuit voltage Voc of QDSSCs with IO-TiO2 electrodes was much higher (0.2 V) than that with nanoparticulate TiO2 electrodes. But short circuit current density Jsc was lower in the case of IO-TiO2 electrodes because of the smaller surface area of IO-TiO2. In this study, for increasing surface area of IO-TiO2, we applied TiCl4 post treatment on IO-TiO2 and investigated the effect of the post treatment on photovoltaic properties of CdSe QD sensitized IO-TiO2 solar cells. It was found that Jsc could be enhanced due to TiCl4 post treatment, but decreased again for more than one cycle treatment, which indicates excess post treatment may lead to worse penetration of electrolyte. Our results indicate that the appropriate post treatment can improve the energy conversion efficiency of the QDSSCs.
文摘WiFi fingerprinting is the method of recording WiFi signal strength from access points （AP） along with the positions at which they were recorded, and later matching those to new mea- surements for indoor positioning. Inertial positioning utilizes the accelerometer and gyroscopes for pedestrian positioning. However, both methods have their limitations, such as the WiFi fluctuations and the accumulative error of inertial sensors. Usually, the filtering method is used for integrating the two approaches to achieve better location accuracy. In the real environments, especially in the indoor field, the APs could be sparse and short range. To overcome the limitations, a novel particle filter approach based on Rao Blackwellized particle filter （RBPF） is presented in this paper. The indoor environment is divided into several local maps, which are assumed to be independent of each other. The local areas are estimated by the local particle filter, whereas the global areas are com- bined by the global particle filter. The algorithm has been investigated by real field trials using a WiFi tablet on hand with an inertial sensor on foot. It could be concluded that the proposed method reduces the complexity of the positioning algorithm obviously, as well as offers a significant improvement in position accuracy compared to other conventional algorithms, allowing indoor positioning error below 1.2 m.
文摘We present the microbial green synthesis of silver nanoparticles （hiPs） by Streptomyces ghanaensis VITHM1 strain （MTCC No. 12465）. The secondary metabolites in the cell free supernatant of this bacterium when incubated with 1 mmol/L AgNO3, mediated the biological synthesis of AgNPs. The synthesized AgNPs were characterized by UV-visible spectrum, X-ray diffrac- tion （XRD）, atomic force microscope, scanning electron microscopy equipped with energy dispersive spectroscopy, transmission electron microscopy, FT-IR spectroscopy, dynamic light scattering and zeta potential. They were highly stable and, spherical in shape with the average size of 30-50 nm. The secondary metabolites involved in the formation of AgNPs were identified gas chromatographymass spectrography. The 3D structure of the unit cell of the synthesized AgNPs was determined using XRD data base. The synthesized AgNPs exhibited significant antibacterial activity against tested bacterial pathogens, and did not show haemolysis on human red blood cells. This green synthesis could provide a new platform to explore and use AgNPs as antibacterial therapeutic agents.
