Multi-level spatial index techniques are always used in large spatial databases. After a general survey of R-tree relevant techniques, this paper presents a novel 2-level index structure, which is based on the schemas...Multi-level spatial index techniques are always used in large spatial databases. After a general survey of R-tree relevant techniques, this paper presents a novel 2-level index structure, which is based on the schemas of spatial grids, Hilbert R-tree and common R-tree. This structure is named H2R-tree, and it is specifically suitable for the indexing highly skewed, distributed, and large spatial database. Algorithms and a sample are given subsequently.展开更多
Based on a special catalyst and fiber Bragg gratings (FBGs), an optical sensing system is proposed to measure the concen- tration of methane. The temperature of the catalyst rises rapidly as the concentration of metha...Based on a special catalyst and fiber Bragg gratings (FBGs), an optical sensing system is proposed to measure the concen- tration of methane. The temperature of the catalyst rises rapidly as the concentration of methane increases, and hence it can be detected by an FBG-type sensor through monitoring the wavelength shift of the reflection spectrum. The experimental results show the good performances of our system, such as the high resolution and temperature stability.展开更多
This paper presents DDGrid, a novel grid computing system for drug discovery and design. By utilizing the idle resources donated by the clusters that scatter over the Intemet, DDGrid can implement efficient data-inten...This paper presents DDGrid, a novel grid computing system for drug discovery and design. By utilizing the idle resources donated by the clusters that scatter over the Intemet, DDGrid can implement efficient data-intensive biologic applications. P2P high-level resource management framework with a GridP2P hybrid architecture is described. With P2P technologies, some problems which are inevitable in the master-slave model can be avoided, such as single point of failure or performance bottleneck. Then an agent-based resource scheduling algorithm is presented. With this scheduling algorithm, the idle computational resources are dynamically scheduled according to the real-time working load on each execution node. Thus DDGrid can hold an excellent load balance state. Furthermore, the framework is introduced into the practical protein molecules docking applications. Solid experimental results show the load balance and robustness of the proposed system, which can greatly speed up the process of protein molecules docking.展开更多
A distributed feedback fiber laser based Bragg grating vibration sensor system is proposed.Demodulated by using an unbalanced M-Z interferometer,experiment demonstrates that the system runs at a sensing sensitivity of...A distributed feedback fiber laser based Bragg grating vibration sensor system is proposed.Demodulated by using an unbalanced M-Z interferometer,experiment demonstrates that the system runs at a sensing sensitivity of about 257.2 rad·s2/m and a resolution of 4.2×10-5 m/s2 for monitoring acceleration.Experimental results show that the phase-shift changes with the acceleration linearly.展开更多
Using the acoustic emission locating technology to monitor the health of the structure is important for ensuring the continuous and healthy operation of the complex engineering structures and large mechanical equipmen...Using the acoustic emission locating technology to monitor the health of the structure is important for ensuring the continuous and healthy operation of the complex engineering structures and large mechanical equipment. In this paper, four fiber Bragg grating(FBG) sensors are used to establish the sensor array to locate the acoustic emission source. Firstly, the nonlinear locating equations are established based on the principle of acoustic emission, and the solution of these equations is transformed into an optimization problem. Secondly, time difference extraction algorithm based on the phase transform(PHAT) weighted generalized cross correlation provides the necessary conditions for the accurate localization. Finally, the genetic algorithm(GA) is used to solve the optimization model. In this paper, twenty points are tested in the marble plate surface, and the results show that the absolute locating error is within the range of 10 mm, which proves the accuracy of this locating method.展开更多
The aim of this project was to develop non-contact fiber optic based displacement sensors to operate in the harsh environment of a ＂light gas gun＂ （LGG）, which can ＂fire＂ small particles at velocities ranging fr...The aim of this project was to develop non-contact fiber optic based displacement sensors to operate in the harsh environment of a ＂light gas gun＂ （LGG）, which can ＂fire＂ small particles at velocities ranging from 1 km/s-8.4km/s. The LGG is used extensively for research in aerospace to analyze the effects of high speed impacts on materials. Ideally the measurement should be made close to the center of the impact to minimize corruption of the data from edge effects and survive the impact. We chose to develop a non-contact ＂pseudo＂ confocal intensity sensor, which demonstrated resolution comparable with conventional polyvinylidene fluoride （PVDF） sensors combined with high survivability and low cost. A second sensor was developed based on ＂fiber Bragg gratings＂ （FBG） to enable a more detailed analysis of the effects of the impact, although requiring contact with the target the low weight and very small contact area of the FBG had minimal effect on the dynamics of the target. The FBG was mounted either on the surface of the target or tangentially between a fixed location. The output signals from the FBG were interrogated in time by a new method. Measurements were made on carbon fiber composite plates in the LGG and on low velocity impact tests. The particle momentum for the low velocity impact tests was chosen to be similar to that of the particles used in the LGG.展开更多
The fiber Bragg grating （FBG） strain sensor is used in the oil and gas derricks for the health monitoring. The system consisted of the FBG strain sensors, optical interrogator and monitoring software. 64 sensors wer...The fiber Bragg grating （FBG） strain sensor is used in the oil and gas derricks for the health monitoring. The system consisted of the FBG strain sensors, optical interrogator and monitoring software. 64 sensors were installed on a derrick for loading and unloading tests. The results showed that the monitoring system had the advantages of the high accuracy, good repeatability, large capacity and real-time monitoring ability.展开更多
文摘Multi-level spatial index techniques are always used in large spatial databases. After a general survey of R-tree relevant techniques, this paper presents a novel 2-level index structure, which is based on the schemas of spatial grids, Hilbert R-tree and common R-tree. This structure is named H2R-tree, and it is specifically suitable for the indexing highly skewed, distributed, and large spatial database. Algorithms and a sample are given subsequently.
基金partially supported by Zhejiang provincial government(under grant No. 2004C31G2010019)Hangzhou municipalgovernment (under grant No. 20051321B14)
文摘Based on a special catalyst and fiber Bragg gratings (FBGs), an optical sensing system is proposed to measure the concen- tration of methane. The temperature of the catalyst rises rapidly as the concentration of methane increases, and hence it can be detected by an FBG-type sensor through monitoring the wavelength shift of the reflection spectrum. The experimental results show the good performances of our system, such as the high resolution and temperature stability.
文摘This paper presents DDGrid, a novel grid computing system for drug discovery and design. By utilizing the idle resources donated by the clusters that scatter over the Intemet, DDGrid can implement efficient data-intensive biologic applications. P2P high-level resource management framework with a GridP2P hybrid architecture is described. With P2P technologies, some problems which are inevitable in the master-slave model can be avoided, such as single point of failure or performance bottleneck. Then an agent-based resource scheduling algorithm is presented. With this scheduling algorithm, the idle computational resources are dynamically scheduled according to the real-time working load on each execution node. Thus DDGrid can hold an excellent load balance state. Furthermore, the framework is introduced into the practical protein molecules docking applications. Solid experimental results show the load balance and robustness of the proposed system, which can greatly speed up the process of protein molecules docking.
基金supported by the Science Fund for Young Scholars of Heilongjiang University,China(No.QL200901)
文摘A distributed feedback fiber laser based Bragg grating vibration sensor system is proposed.Demodulated by using an unbalanced M-Z interferometer,experiment demonstrates that the system runs at a sensing sensitivity of about 257.2 rad·s2/m and a resolution of 4.2×10-5 m/s2 for monitoring acceleration.Experimental results show that the phase-shift changes with the acceleration linearly.
基金supported by the National Natural Science Foundation of China(No.41472260)the Fundamental Research Funds of Shandong University(No.2016JC012)the Young Scholars Program of Shandong University(No.2016WLJH30)
文摘Using the acoustic emission locating technology to monitor the health of the structure is important for ensuring the continuous and healthy operation of the complex engineering structures and large mechanical equipment. In this paper, four fiber Bragg grating(FBG) sensors are used to establish the sensor array to locate the acoustic emission source. Firstly, the nonlinear locating equations are established based on the principle of acoustic emission, and the solution of these equations is transformed into an optimization problem. Secondly, time difference extraction algorithm based on the phase transform(PHAT) weighted generalized cross correlation provides the necessary conditions for the accurate localization. Finally, the genetic algorithm(GA) is used to solve the optimization model. In this paper, twenty points are tested in the marble plate surface, and the results show that the absolute locating error is within the range of 10 mm, which proves the accuracy of this locating method.
文摘The aim of this project was to develop non-contact fiber optic based displacement sensors to operate in the harsh environment of a ＂light gas gun＂ （LGG）, which can ＂fire＂ small particles at velocities ranging from 1 km/s-8.4km/s. The LGG is used extensively for research in aerospace to analyze the effects of high speed impacts on materials. Ideally the measurement should be made close to the center of the impact to minimize corruption of the data from edge effects and survive the impact. We chose to develop a non-contact ＂pseudo＂ confocal intensity sensor, which demonstrated resolution comparable with conventional polyvinylidene fluoride （PVDF） sensors combined with high survivability and low cost. A second sensor was developed based on ＂fiber Bragg gratings＂ （FBG） to enable a more detailed analysis of the effects of the impact, although requiring contact with the target the low weight and very small contact area of the FBG had minimal effect on the dynamics of the target. The FBG was mounted either on the surface of the target or tangentially between a fixed location. The output signals from the FBG were interrogated in time by a new method. Measurements were made on carbon fiber composite plates in the LGG and on low velocity impact tests. The particle momentum for the low velocity impact tests was chosen to be similar to that of the particles used in the LGG.
文摘The fiber Bragg grating （FBG） strain sensor is used in the oil and gas derricks for the health monitoring. The system consisted of the FBG strain sensors, optical interrogator and monitoring software. 64 sensors were installed on a derrick for loading and unloading tests. The results showed that the monitoring system had the advantages of the high accuracy, good repeatability, large capacity and real-time monitoring ability.
