After six years of Himrod grape regional trial, the Himrod had very early- ripening precocity, stable flower bud differentiation, good fruit quality and great resis- tance to diseases, which could be a moderate develo...After six years of Himrod grape regional trial, the Himrod had very early- ripening precocity, stable flower bud differentiation, good fruit quality and great resis- tance to diseases, which could be a moderate development grape variety in Tianjin. The introduction performance cultivation techniques of Himrod grape were summa- rized.展开更多
In this paper, by using the optimal stopping theory, the semilinear Black-Scholes partial differential equation （PDE） was invesigated in a fixed domain for valuing two assets of American （call-max/put-min） options...In this paper, by using the optimal stopping theory, the semilinear Black-Scholes partial differential equation （PDE） was invesigated in a fixed domain for valuing two assets of American （call-max/put-min） options. From the viscosity solution of a PDE, a unique viscosity solution was obtained for the semilinear Black-Scholes PDE.展开更多
A recent technique, using to potentially replace the conventional impregnating one in low voltage electric motors, has been studied in this communication. The conventional technique that uses?both primary and secondar...A recent technique, using to potentially replace the conventional impregnating one in low voltage electric motors, has been studied in this communication. The conventional technique that uses?both primary and secondary insulations;?i.e.: enamel and varnish, has been compared to this recent technique which only uses one component,?i.e.: self-bonding wires. Self-bonding wires polymerization is very quick compared to that of the conventional technique. Environmental impact and both dielectric and mechanical properties of these two techniques have been estimated and compared. The goal is to estimate if this recent technique has not only a better environmental footprint but also good technical properties. The dielectric properties that have been measured are the dielectric strength and?the lifetime under pulse?voltage while mechanical consists in measuring the bonding strength that is crucial for impregnation.?For that purpose, a Life Cycle Assessment (LCA) that can simultaneously evaluatenumerous impacts on ground, water and air,?has been performed. The results show clearly that the recent technique significantly reduces the environmental footprint. Both mechanical and dielectric properties are then compared and analyzed.展开更多
Internet of Things (IoT) is ubiquitous, including objects or devices communicating through heterogenous wireless networks. One of the major challenges in mobile IoT is an efficient vertical handover decision (VHD) tec...Internet of Things (IoT) is ubiquitous, including objects or devices communicating through heterogenous wireless networks. One of the major challenges in mobile IoT is an efficient vertical handover decision (VHD) technique between heterogenous networks for seamless connectivity with constrained resources. The conventional VHD approach is mainly based on received signal strength (RSS). The approach is inefficient for vertical handover, since it always selects the target network with the strongest signal without taking into consideration of factors such as quality of service (QoS), cost, delay, etc. In this paper, we present a hybrid approach by integrating the multi-cri- teria based VHD (MCVHD) technique and an algorithm based on fuzzy logic for efficient VHD among Wi-Fi, Radio and Satellite networks. The MCVHD provides a lightweight solution that aims to achieving seamless connectivity for mobile IoT Edge Gateway over a set of heterogeneous networks. The proposed solution is evaluated in real time using a testbed containing real IoT devices. Further, the testbed is integrated with lightweight and efficient software techniques, e.g., microservices, containers, broker, and Edge/Cloud techniques. The experimental results show that the proposed approach is suitable for an IoT environment and it outperforms the conventional RSS Quality based VHD by minimizing handover failures, unnecessary handovers, handover time and cost of service.展开更多
叶端定时(Blade Tip Timing, BTT)是当前研究叶片振动问题最有效的测试技术之一,被广泛应用于动叶片的状态监测与故障诊断。然而,BTT技术固有的非均匀、欠采样特性引发的叶片振动参数辨识困难已成为当前BTT技术亟需解决的难题。首先,研...叶端定时(Blade Tip Timing, BTT)是当前研究叶片振动问题最有效的测试技术之一,被广泛应用于动叶片的状态监测与故障诊断。然而,BTT技术固有的非均匀、欠采样特性引发的叶片振动参数辨识困难已成为当前BTT技术亟需解决的难题。首先,研究旋转不变子空间(Estimating Signal Parameter via Rotational Invariance Techniques, ESPRIT)和快速傅里叶变换(Fast Fourier Transform, FFT)辨识叶片振动参数的特征;然后,对叶片振动的频谱分析结果进行扩展;最后,提出一种融合ESPRIT和FFT的动叶片振动参数辨识方法。ESPRIT-FFT方法利用扩展频谱寻找叶片振动频率的估计值,通过ESPRIT算法确定频率所属的频带,进而辨识叶片振动参数。仿真研究证明了ESPRIT-FFT方法的可行性和抗噪性。离心压缩机叶轮振动试验显示ESPRIT-FFT方法辨识叶片振动频率的绝对误差为1.4 Hz,相对误差为0.22%。展开更多
Telescopes with large aspherical primary mirrors collect more light and are therefore sought after by astronomers. Instead of using a single large one-piece mirror, smaller segments can be assembled into a useable tel...Telescopes with large aspherical primary mirrors collect more light and are therefore sought after by astronomers. Instead of using a single large one-piece mirror, smaller segments can be assembled into a useable telescopic primary. Because the segments must fit together to create the effect of a single mirror, segmented optics present unique challenges to the fabrication and testing that are absent in monolithic optics. A dispersed fringe sensor （DFS） using a broadband point source is an efficient method for cophasing and is also highly automated and robust. Unlike the widely adopted Shack- Hartmann Wavefront sensor and curvature wavefront sensor with edge sensors for calibration of relative pistons, DFS can estimate the piston between segments by only using the spectrum formed by the transmissive grating＇s dispersion, and therefore can replace the edge sensors, which are difficult to calibrate. We introduce the theory of the DFS and Dispersed Hartmann Sensor （DHS） for further utilization of the coarse phasing method of DFS. According to the theory, we bring out the preliminary system design of the cophasing experimental system based on DFS and DHS which is now established in our institute. Finally, a summary is reached.展开更多
基金Supported by Key Program of Applied Basic and Frontier Technology Research Foundation of Tianjin(14JCZDJC34400)Special Fund for Modern Agricultural Technology System(CARS-30)Transformation and Extension Of Agricultural Science and Technology Achievements in Tianjin(201304120)~~
文摘After six years of Himrod grape regional trial, the Himrod had very early- ripening precocity, stable flower bud differentiation, good fruit quality and great resis- tance to diseases, which could be a moderate development grape variety in Tianjin. The introduction performance cultivation techniques of Himrod grape were summa- rized.
基金Project supported by the National Natural Science Foundation of China (Grant No.10271072)
文摘In this paper, by using the optimal stopping theory, the semilinear Black-Scholes partial differential equation （PDE） was invesigated in a fixed domain for valuing two assets of American （call-max/put-min） options. From the viscosity solution of a PDE, a unique viscosity solution was obtained for the semilinear Black-Scholes PDE.
文摘A recent technique, using to potentially replace the conventional impregnating one in low voltage electric motors, has been studied in this communication. The conventional technique that uses?both primary and secondary insulations;?i.e.: enamel and varnish, has been compared to this recent technique which only uses one component,?i.e.: self-bonding wires. Self-bonding wires polymerization is very quick compared to that of the conventional technique. Environmental impact and both dielectric and mechanical properties of these two techniques have been estimated and compared. The goal is to estimate if this recent technique has not only a better environmental footprint but also good technical properties. The dielectric properties that have been measured are the dielectric strength and?the lifetime under pulse?voltage while mechanical consists in measuring the bonding strength that is crucial for impregnation.?For that purpose, a Life Cycle Assessment (LCA) that can simultaneously evaluatenumerous impacts on ground, water and air,?has been performed. The results show clearly that the recent technique significantly reduces the environmental footprint. Both mechanical and dielectric properties are then compared and analyzed.
文摘Internet of Things (IoT) is ubiquitous, including objects or devices communicating through heterogenous wireless networks. One of the major challenges in mobile IoT is an efficient vertical handover decision (VHD) technique between heterogenous networks for seamless connectivity with constrained resources. The conventional VHD approach is mainly based on received signal strength (RSS). The approach is inefficient for vertical handover, since it always selects the target network with the strongest signal without taking into consideration of factors such as quality of service (QoS), cost, delay, etc. In this paper, we present a hybrid approach by integrating the multi-cri- teria based VHD (MCVHD) technique and an algorithm based on fuzzy logic for efficient VHD among Wi-Fi, Radio and Satellite networks. The MCVHD provides a lightweight solution that aims to achieving seamless connectivity for mobile IoT Edge Gateway over a set of heterogeneous networks. The proposed solution is evaluated in real time using a testbed containing real IoT devices. Further, the testbed is integrated with lightweight and efficient software techniques, e.g., microservices, containers, broker, and Edge/Cloud techniques. The experimental results show that the proposed approach is suitable for an IoT environment and it outperforms the conventional RSS Quality based VHD by minimizing handover failures, unnecessary handovers, handover time and cost of service.
文摘叶端定时(Blade Tip Timing, BTT)是当前研究叶片振动问题最有效的测试技术之一,被广泛应用于动叶片的状态监测与故障诊断。然而,BTT技术固有的非均匀、欠采样特性引发的叶片振动参数辨识困难已成为当前BTT技术亟需解决的难题。首先,研究旋转不变子空间(Estimating Signal Parameter via Rotational Invariance Techniques, ESPRIT)和快速傅里叶变换(Fast Fourier Transform, FFT)辨识叶片振动参数的特征;然后,对叶片振动的频谱分析结果进行扩展;最后,提出一种融合ESPRIT和FFT的动叶片振动参数辨识方法。ESPRIT-FFT方法利用扩展频谱寻找叶片振动频率的估计值,通过ESPRIT算法确定频率所属的频带,进而辨识叶片振动参数。仿真研究证明了ESPRIT-FFT方法的可行性和抗噪性。离心压缩机叶轮振动试验显示ESPRIT-FFT方法辨识叶片振动频率的绝对误差为1.4 Hz,相对误差为0.22%。
基金supported by the National Natural Science Foundation of China(Grant No. 10703008)
文摘Telescopes with large aspherical primary mirrors collect more light and are therefore sought after by astronomers. Instead of using a single large one-piece mirror, smaller segments can be assembled into a useable telescopic primary. Because the segments must fit together to create the effect of a single mirror, segmented optics present unique challenges to the fabrication and testing that are absent in monolithic optics. A dispersed fringe sensor （DFS） using a broadband point source is an efficient method for cophasing and is also highly automated and robust. Unlike the widely adopted Shack- Hartmann Wavefront sensor and curvature wavefront sensor with edge sensors for calibration of relative pistons, DFS can estimate the piston between segments by only using the spectrum formed by the transmissive grating＇s dispersion, and therefore can replace the edge sensors, which are difficult to calibrate. We introduce the theory of the DFS and Dispersed Hartmann Sensor （DHS） for further utilization of the coarse phasing method of DFS. According to the theory, we bring out the preliminary system design of the cophasing experimental system based on DFS and DHS which is now established in our institute. Finally, a summary is reached.
