Method of testing for dynamic output forces from jet elements is studied, the handwidth is large in testing with this method. By establishing a model of the test system and simulating it, principles of how inherent fe...Method of testing for dynamic output forces from jet elements is studied, the handwidth is large in testing with this method. By establishing a model of the test system and simulating it, principles of how inherent features of the test system affect the dynamic force test are found out. Thus a theoretical foundation is given for the design and error modification to the actual test system.展开更多
According to the existing problems of liquefaction models of saturated sand that were put forward under dynamic action,on the basis of Handin-Drnevich model,a new calculating model of the dynamic constitutive relation...According to the existing problems of liquefaction models of saturated sand that were put forward under dynamic action,on the basis of Handin-Drnevich model,a new calculating model of the dynamic constitutive relation of saturated sand was put forward.The model was based on the basic hypothesis of instantaneous limit balance according to the basic principle that the stress estate is the destroyed condition was not overstepped.The calculated method of increment nonlinear was referenced and combined with the excellence of the model of distributed particles.The process of vibrating liquefaction of saturated sand was divided into some areas.And the phenomena of shearing dilatation and unloading shrink of saturated sand were considered.On above basic a new calculating constitutive relation model was proposed.There are a few parameters in the model.The physical means of the parameters are very evident and quantized.They could be obtained from the dynamic triaxial test in door.The model was contrasted and validated with the results of the dynamic triaxial test in door.The comparison of the results of the dynamic triaxial test in door and the calculating results of the model indicates that all sorts of phenomenon appearing in the process of liquefaction of saturated sand could be more perfectly reflected by the model.Especially at the initial stage of development of pore water pressure and strain of saturated sand,the results of the dynamic triaxial test in door are consistent with the calculated results of the model very much.But there is some difference between the results at the anaphase of development of pore water pressure and strain.On the path of stress,the calculating and experimenting ultimate state surfaces are almost identical.展开更多
The dynamic reactive power compensation equipment in Jiuquan Wind Power Base of above 10 GW consists of three different types of compensation devices, including： static var generator （SVG）, thyristor controlled com...The dynamic reactive power compensation equipment in Jiuquan Wind Power Base of above 10 GW consists of three different types of compensation devices, including： static var generator （SVG）, thyristor controlled compensator （TGR） and magnetically controlled reactor （MGR）. The lack of experimental verification of performance is not conducive to voltage/var management or full utilization of device capaci- ties. In order to solve the above problems, the compensation device performance test was performed. The test items and procedures were selected based on related national standards with the consideration for different grid structures and wind farm operation modes. The testing contents included dynamic regulating range, active power loss, dynamic response time, and harmonic voltage level. Three types of compensation devices installed in different wind farms, namely SVG, TCR and MCR, were chosen and tested. The performances were compared and analyzed according to the field test results.展开更多
Objective:To observe the clinical efficacy of heat-sensitive moxibustion for vascular dementia and explore its mechanism.Methods:A total of 70 patients with vascular dementia were randomized into an observation group ...Objective:To observe the clinical efficacy of heat-sensitive moxibustion for vascular dementia and explore its mechanism.Methods:A total of 70 patients with vascular dementia were randomized into an observation group and a control group,with 35 cases in each group.The control group was treated with piracetam,and the observation group was treated with heat-sensitive moxibustion on the basis of the treatment of the control group.The treatment lasted for 8 weeks.Before and after the treatment,the mini-mental state examination(MMSE),activity of daily living(ADL)and traditional Chinese medicine(TCM)symptom scores were assessed,and the levels of acetyl choline(Ach)and homocysteine(Hcy)were measured.The efficacy was evaluated after treatment.Results:The total effective rate of the observation group was significantly higher than that of the control group(P<0.05).After treatment,the MMSE and ADL scores in the observation group decreased significantly,and were lower than those in the control group(all P<0.05);the TCM symptom score of the observation group decreased significantly(P<0.05),while that of the control group had no significant change(P>0.05);the plasma Ach level in the observation group increased significantly(P<0.05),and the Hcy level decreased significantly(P<0.05),which were statistically different from those in the control group(both P<0.05).Conclusion:Heat-sensitive moxibustion plus piracetam is effective in treating vascular dementia.It can significantly improve dementia symptoms and ADL,which may be related to the correction of plasma Ach and Hcy levels.展开更多
Herein symmetrical four-legged suspension lunar lander was used as the research object, the six-degree-of-freedom dynamic model was built and the model of the lunar soil friction coefficient was improved. For the low-...Herein symmetrical four-legged suspension lunar lander was used as the research object, the six-degree-of-freedom dynamic model was built and the model of the lunar soil friction coefficient was improved. For the low-gravity simulation on objects outside earth for future work, the law of dynamic similarity for detectors was deduced. A new method was proposed for simulating the low-gravity field on the surface of objects outside earth, which was achieved by changing initial conditions of the landing by the probe and by subsequent treatment of experimental data. The prototype tested the limitation of this method was verified. It is shown that the prototypes of detectors can be used in detectors low-gravity simulation test with this method, and equipments are simple and operationally effective. This method can be used for later lunar exploration, and low-gravity simulations on extraterrestrial objects.展开更多
文摘Method of testing for dynamic output forces from jet elements is studied, the handwidth is large in testing with this method. By establishing a model of the test system and simulating it, principles of how inherent features of the test system affect the dynamic force test are found out. Thus a theoretical foundation is given for the design and error modification to the actual test system.
基金Project(59979001) supported by the National Natural Science Foundation of China
文摘According to the existing problems of liquefaction models of saturated sand that were put forward under dynamic action,on the basis of Handin-Drnevich model,a new calculating model of the dynamic constitutive relation of saturated sand was put forward.The model was based on the basic hypothesis of instantaneous limit balance according to the basic principle that the stress estate is the destroyed condition was not overstepped.The calculated method of increment nonlinear was referenced and combined with the excellence of the model of distributed particles.The process of vibrating liquefaction of saturated sand was divided into some areas.And the phenomena of shearing dilatation and unloading shrink of saturated sand were considered.On above basic a new calculating constitutive relation model was proposed.There are a few parameters in the model.The physical means of the parameters are very evident and quantized.They could be obtained from the dynamic triaxial test in door.The model was contrasted and validated with the results of the dynamic triaxial test in door.The comparison of the results of the dynamic triaxial test in door and the calculating results of the model indicates that all sorts of phenomenon appearing in the process of liquefaction of saturated sand could be more perfectly reflected by the model.Especially at the initial stage of development of pore water pressure and strain of saturated sand,the results of the dynamic triaxial test in door are consistent with the calculated results of the model very much.But there is some difference between the results at the anaphase of development of pore water pressure and strain.On the path of stress,the calculating and experimenting ultimate state surfaces are almost identical.
文摘The dynamic reactive power compensation equipment in Jiuquan Wind Power Base of above 10 GW consists of three different types of compensation devices, including： static var generator （SVG）, thyristor controlled compensator （TGR） and magnetically controlled reactor （MGR）. The lack of experimental verification of performance is not conducive to voltage/var management or full utilization of device capaci- ties. In order to solve the above problems, the compensation device performance test was performed. The test items and procedures were selected based on related national standards with the consideration for different grid structures and wind farm operation modes. The testing contents included dynamic regulating range, active power loss, dynamic response time, and harmonic voltage level. Three types of compensation devices installed in different wind farms, namely SVG, TCR and MCR, were chosen and tested. The performances were compared and analyzed according to the field test results.
文摘Objective:To observe the clinical efficacy of heat-sensitive moxibustion for vascular dementia and explore its mechanism.Methods:A total of 70 patients with vascular dementia were randomized into an observation group and a control group,with 35 cases in each group.The control group was treated with piracetam,and the observation group was treated with heat-sensitive moxibustion on the basis of the treatment of the control group.The treatment lasted for 8 weeks.Before and after the treatment,the mini-mental state examination(MMSE),activity of daily living(ADL)and traditional Chinese medicine(TCM)symptom scores were assessed,and the levels of acetyl choline(Ach)and homocysteine(Hcy)were measured.The efficacy was evaluated after treatment.Results:The total effective rate of the observation group was significantly higher than that of the control group(P<0.05).After treatment,the MMSE and ADL scores in the observation group decreased significantly,and were lower than those in the control group(all P<0.05);the TCM symptom score of the observation group decreased significantly(P<0.05),while that of the control group had no significant change(P>0.05);the plasma Ach level in the observation group increased significantly(P<0.05),and the Hcy level decreased significantly(P<0.05),which were statistically different from those in the control group(both P<0.05).Conclusion:Heat-sensitive moxibustion plus piracetam is effective in treating vascular dementia.It can significantly improve dementia symptoms and ADL,which may be related to the correction of plasma Ach and Hcy levels.
基金supported by the National Natural Science Foundation of China(Grant No.51105196)Natural Science Foundation of Jiangsu Province(Grant No.BK2011733)
文摘Herein symmetrical four-legged suspension lunar lander was used as the research object, the six-degree-of-freedom dynamic model was built and the model of the lunar soil friction coefficient was improved. For the low-gravity simulation on objects outside earth for future work, the law of dynamic similarity for detectors was deduced. A new method was proposed for simulating the low-gravity field on the surface of objects outside earth, which was achieved by changing initial conditions of the landing by the probe and by subsequent treatment of experimental data. The prototype tested the limitation of this method was verified. It is shown that the prototypes of detectors can be used in detectors low-gravity simulation test with this method, and equipments are simple and operationally effective. This method can be used for later lunar exploration, and low-gravity simulations on extraterrestrial objects.
