The dynamics model of the transmission system of the internal grinder is established on the bases of Riccati transfer matrix. The dynamic characteristics of the internal grinder are obtained by analyzing the relations...The dynamics model of the transmission system of the internal grinder is established on the bases of Riccati transfer matrix. The dynamic characteristics of the internal grinder are obtained by analyzing the relationship between dynamic modal flexibility and modal flexibility, which is used to find out the dangerous model of the transmission system and its weak areas. Then design parameters of weak areas are modified, the new one from the old structure is put forward, and the dynamic characteristics of new ...展开更多
Found in the Trans-Himalayas of north-west Yunnan and south-east Tibet, the black-and-white snub-nosed monkey （Rhinopithecus bieti） is one of the world’s most endangered primates. A recent survey indicates that onl...Found in the Trans-Himalayas of north-west Yunnan and south-east Tibet, the black-and-white snub-nosed monkey （Rhinopithecus bieti） is one of the world’s most endangered primates. A recent survey indicates that only 15 groups with 2500 individuals remain in the wild. However, the Tibetan Xiaochangdu group may be the only equilibrium group in the field since the last investigation in 1988. To evaluate the effects of traditional culture and socioeconomic activity on biodiversity conservation of R. bieti, we conducted a case study in the Honglaxueshan National Nature Reserve in southeast Tibet from June 2003 to May 2005. Interviews, direct observations, and analysis of socioeconomic data indicated major advantages to the conservation of R. bieti, which included that： 1） traditional culture mainly depended on raising livestock and collecting non-timber products rather than forest planting of Tibetan highland barley; 2） religious beliefs, against to kill any wildlife living on the sacred mountain, were mainly influenced by Tibetan Buddhism; and 3） bigger household numbers were induced by the polyandrous marriage system, which resulted in lower per capita resource consumption than smaller ones.展开更多
Flight delay prediction remains an important research topic due to dynamic nature in flight operation and numerous delay factors.Dynamic data-driven application system in the control area can provide a solution to thi...Flight delay prediction remains an important research topic due to dynamic nature in flight operation and numerous delay factors.Dynamic data-driven application system in the control area can provide a solution to this problem.However,in order to apply the approach,a state-space flight delay model needs to be established to represent the relationship among system states,as well as the relationship between system states and input/output variables.Based on the analysis of delay event sequence in a single flight,a state-space mixture model is established and input variables in the model are studied.Case study is also carried out on historical flight delay data.In addition,the genetic expectation-maximization（EM）algorithm is used to obtain the global optimal estimates of parameters in the mixture model,and results fit the historical data.At last,the model is validated in Kolmogorov-Smirnov tests.Results show that the model has reasonable goodness of fitting the data,and the search performance of traditional EM algorithm can be improved by using the genetic algorithm.展开更多
Aim To find an effective method to remove the registration error in multi-sensor systems. Methods A Kalman filtering technique was proposed to estimate and remove sensor bias and sensor fare tilt errors in multisenso...Aim To find an effective method to remove the registration error in multi-sensor systems. Methods A Kalman filtering technique was proposed to estimate and remove sensor bias and sensor fare tilt errors in multisensor systems with a moving platform. Results Simulation results are presented to demonstrate the performance of the approach. Conclusion The Kalman filter algorithm am detect registration errors and use this information to converge tracks from independent sensors. This is particularly important if the data from the sensors are to fused.展开更多
To reduce shock during transmission gear shift, a transmission torque feedback closed loop control system is proposed based on the powertrain system model and a torque observer. The ignition time of engine was delaye...To reduce shock during transmission gear shift, a transmission torque feedback closed loop control system is proposed based on the powertrain system model and a torque observer. The ignition time of engine was delayed to reduce transmission output shaft torque during gear shift. In contrast to traditional control method, the closed loop control system based on torque observer can obviously reduce the transmission output shaft torque during gear shift. It can be concluded that by way of torque feedback closed loop control, transmission shift shock can be reduced.展开更多
This paper introduces the design and implementation of sea-water temperature auto-monitoring system based on General Packet Radio Service （GPRS）. This system integrates modern wireless communication technology, the ...This paper introduces the design and implementation of sea-water temperature auto-monitoring system based on General Packet Radio Service （GPRS）. This system integrates modern wireless communication technology, the signal gathering technology and computer network technology. MSC1210 microcontroller is used in data collection device in order to make system accurate and fast. In addition, wireless and Internet technologies are used for transferring and displaying collected field data. A prototype system has been completed and tested in field trials. The results proved the feasibility and usefulness of this system for monitoring the temperature. By using this system, a lot of resources and money can be saved.展开更多
According to the deficiency of experiment system for gas adsorption and desorption in coal mass, a large scale experiment system is developed independently by researchers. This experiment system is composed of primary...According to the deficiency of experiment system for gas adsorption and desorption in coal mass, a large scale experiment system is developed independently by researchers. This experiment system is composed of primary and auxiliary boxes, power transmission system, mining system, loading system, gas charging system, data monitoring and intelligent acquisition system. The maximum experiment coal consumption is 1200 kg, the mining system is developed to conduct experiment for gas desorption under excavating disturbance, and the plane-charging cribriform ventilation device is developed to realize uniform ventilation for experiment coal sample, which is accord with the actual gas source situation of coal bed. The desorption characteristics of gas in coal are experimentally studied under the conditions of nature and mining using the experiment system. The results show that, compare with nature condition, the permeability of coal and the velocity of gas desorption could significantly increase under the influence of coal pressure relief and destruction caused by mining, and the degree of gas desorption could somewhat increase too. Finally, pressure relief gas extraction of current seam and adjacent seams after mining in a certain coal mine of Yangquan mining area are introduced, and the gas desorption experiment results is verified by analyzing the effect of gas extraction.展开更多
The primary focus of this study is to investigate the control strategies of a hybrid system used in hydraulic excavators. First, the structure and evaluation target of hybrid hydraulic excavators are analyzed. Then th...The primary focus of this study is to investigate the control strategies of a hybrid system used in hydraulic excavators. First, the structure and evaluation target of hybrid hydraulic excavators are analyzed. Then the dynamic system model including batteries, motor and engine is built as the simulation environment to obtain control results. A so-called multi-work-point dynamic control strategy, which has both closed-loop speed PI (proportion integral) control and direct torque control, is proposed and studied in the simulation model. Simulation results indicate that the hybrid system with this strategy can meet the power demand and achieve better system stability and higher fuel efficiency.展开更多
Based on the theories of hydraulics and nonlinear control system, the model of hydroviscous drive (HVD) was established, the influences of small ripple of control oil pressure on the output speed of HVD and the stabil...Based on the theories of hydraulics and nonlinear control system, the model of hydroviscous drive (HVD) was established, the influences of small ripple of control oil pressure on the output speed of HVD and the stability of oil film between friction disks were analyzed. The conclusion presents that when the frequency of the control oil's pressure ripple is higher than 60?Hz and the peak is less than 0 05?MPa, HVD can work stably. The result is useful for studying the application of frequency conversion technology in regulation of control oil pressure.展开更多
With the analysis on regulating system in 200 MW steam turbine, the necessity of appending the fast-opening function to the original system is set forth and a new type of fast-opening mechanism is devised. The mathema...With the analysis on regulating system in 200 MW steam turbine, the necessity of appending the fast-opening function to the original system is set forth and a new type of fast-opening mechanism is devised. The mathematical model of system is built up. With the use of AMESIM software, the displacement curve of the piston, the force curve of the cartridge valve spool, the pressure curve and the flux curve in the regulation process are obtained based on simulation. The performances of three fast-opening systems composed of cartridge valves with different diameters are compared. Based on the analysis on factors that affect the execution time of fast-opening, the dead zone of the fast-opening system is put forward. To overcome the defect, dif- ferent operation modes are adopted for different zones. The result shows that with the increase of the valve diameter, the regulating time in the dead zone significantly exceeds the fast-opening time in the whole journey. Accordingly, the optimization operation tactic in the dead zone and the qualification conditions are brought forward. The fast-opening system composed of 32 mm cartridge valves is taken as an example with use of the tactic. The simulation result shows that the maximum regulating time is shortened by 509 ms.展开更多
文摘The dynamics model of the transmission system of the internal grinder is established on the bases of Riccati transfer matrix. The dynamic characteristics of the internal grinder are obtained by analyzing the relationship between dynamic modal flexibility and modal flexibility, which is used to find out the dangerous model of the transmission system and its weak areas. Then design parameters of weak areas are modified, the new one from the old structure is put forward, and the dynamic characteristics of new ...
基金supported by the Chinese Academy of Sciences (KSCX2-1-03)the National Natural Science Foundation of China (30870375, 31071937)the Central South University of Forestry & Technology (101-0654)
文摘Found in the Trans-Himalayas of north-west Yunnan and south-east Tibet, the black-and-white snub-nosed monkey （Rhinopithecus bieti） is one of the world’s most endangered primates. A recent survey indicates that only 15 groups with 2500 individuals remain in the wild. However, the Tibetan Xiaochangdu group may be the only equilibrium group in the field since the last investigation in 1988. To evaluate the effects of traditional culture and socioeconomic activity on biodiversity conservation of R. bieti, we conducted a case study in the Honglaxueshan National Nature Reserve in southeast Tibet from June 2003 to May 2005. Interviews, direct observations, and analysis of socioeconomic data indicated major advantages to the conservation of R. bieti, which included that： 1） traditional culture mainly depended on raising livestock and collecting non-timber products rather than forest planting of Tibetan highland barley; 2） religious beliefs, against to kill any wildlife living on the sacred mountain, were mainly influenced by Tibetan Buddhism; and 3） bigger household numbers were induced by the polyandrous marriage system, which resulted in lower per capita resource consumption than smaller ones.
基金Supported by the High Technology Research and Development Programme of China(2006AA12A106)~~
文摘Flight delay prediction remains an important research topic due to dynamic nature in flight operation and numerous delay factors.Dynamic data-driven application system in the control area can provide a solution to this problem.However,in order to apply the approach,a state-space flight delay model needs to be established to represent the relationship among system states,as well as the relationship between system states and input/output variables.Based on the analysis of delay event sequence in a single flight,a state-space mixture model is established and input variables in the model are studied.Case study is also carried out on historical flight delay data.In addition,the genetic expectation-maximization（EM）algorithm is used to obtain the global optimal estimates of parameters in the mixture model,and results fit the historical data.At last,the model is validated in Kolmogorov-Smirnov tests.Results show that the model has reasonable goodness of fitting the data,and the search performance of traditional EM algorithm can be improved by using the genetic algorithm.
文摘Aim To find an effective method to remove the registration error in multi-sensor systems. Methods A Kalman filtering technique was proposed to estimate and remove sensor bias and sensor fare tilt errors in multisensor systems with a moving platform. Results Simulation results are presented to demonstrate the performance of the approach. Conclusion The Kalman filter algorithm am detect registration errors and use this information to converge tracks from independent sensors. This is particularly important if the data from the sensors are to fused.
文摘To reduce shock during transmission gear shift, a transmission torque feedback closed loop control system is proposed based on the powertrain system model and a torque observer. The ignition time of engine was delayed to reduce transmission output shaft torque during gear shift. In contrast to traditional control method, the closed loop control system based on torque observer can obviously reduce the transmission output shaft torque during gear shift. It can be concluded that by way of torque feedback closed loop control, transmission shift shock can be reduced.
文摘This paper introduces the design and implementation of sea-water temperature auto-monitoring system based on General Packet Radio Service （GPRS）. This system integrates modern wireless communication technology, the signal gathering technology and computer network technology. MSC1210 microcontroller is used in data collection device in order to make system accurate and fast. In addition, wireless and Internet technologies are used for transferring and displaying collected field data. A prototype system has been completed and tested in field trials. The results proved the feasibility and usefulness of this system for monitoring the temperature. By using this system, a lot of resources and money can be saved.
基金Acknowledgments This work is supported by the National Key Basic Research Program of China （2013CB227903） and the National Natural Science Foundation of China （U1361209）.
文摘According to the deficiency of experiment system for gas adsorption and desorption in coal mass, a large scale experiment system is developed independently by researchers. This experiment system is composed of primary and auxiliary boxes, power transmission system, mining system, loading system, gas charging system, data monitoring and intelligent acquisition system. The maximum experiment coal consumption is 1200 kg, the mining system is developed to conduct experiment for gas desorption under excavating disturbance, and the plane-charging cribriform ventilation device is developed to realize uniform ventilation for experiment coal sample, which is accord with the actual gas source situation of coal bed. The desorption characteristics of gas in coal are experimentally studied under the conditions of nature and mining using the experiment system. The results show that, compare with nature condition, the permeability of coal and the velocity of gas desorption could significantly increase under the influence of coal pressure relief and destruction caused by mining, and the degree of gas desorption could somewhat increase too. Finally, pressure relief gas extraction of current seam and adjacent seams after mining in a certain coal mine of Yangquan mining area are introduced, and the gas desorption experiment results is verified by analyzing the effect of gas extraction.
基金Project (No. 2006C11148) supported by the ScienceTechnology Project of Zhejiang Province, China
文摘The primary focus of this study is to investigate the control strategies of a hybrid system used in hydraulic excavators. First, the structure and evaluation target of hybrid hydraulic excavators are analyzed. Then the dynamic system model including batteries, motor and engine is built as the simulation environment to obtain control results. A so-called multi-work-point dynamic control strategy, which has both closed-loop speed PI (proportion integral) control and direct torque control, is proposed and studied in the simulation model. Simulation results indicate that the hybrid system with this strategy can meet the power demand and achieve better system stability and higher fuel efficiency.
文摘Based on the theories of hydraulics and nonlinear control system, the model of hydroviscous drive (HVD) was established, the influences of small ripple of control oil pressure on the output speed of HVD and the stability of oil film between friction disks were analyzed. The conclusion presents that when the frequency of the control oil's pressure ripple is higher than 60?Hz and the peak is less than 0 05?MPa, HVD can work stably. The result is useful for studying the application of frequency conversion technology in regulation of control oil pressure.
基金Project (No. NCET-04-0545) supported by the "New Century Elitist Supporting Plan" Fund Project of Education Ministry of China
文摘With the analysis on regulating system in 200 MW steam turbine, the necessity of appending the fast-opening function to the original system is set forth and a new type of fast-opening mechanism is devised. The mathematical model of system is built up. With the use of AMESIM software, the displacement curve of the piston, the force curve of the cartridge valve spool, the pressure curve and the flux curve in the regulation process are obtained based on simulation. The performances of three fast-opening systems composed of cartridge valves with different diameters are compared. Based on the analysis on factors that affect the execution time of fast-opening, the dead zone of the fast-opening system is put forward. To overcome the defect, dif- ferent operation modes are adopted for different zones. The result shows that with the increase of the valve diameter, the regulating time in the dead zone significantly exceeds the fast-opening time in the whole journey. Accordingly, the optimization operation tactic in the dead zone and the qualification conditions are brought forward. The fast-opening system composed of 32 mm cartridge valves is taken as an example with use of the tactic. The simulation result shows that the maximum regulating time is shortened by 509 ms.
