A force control strategy for position controlled robotic manipulators is presented. On line force feedback data are employed to estimate the local shape of the unknown constraint. The estimated vectors are used to ge...A force control strategy for position controlled robotic manipulators is presented. On line force feedback data are employed to estimate the local shape of the unknown constraint. The estimated vectors are used to generate the virtual reference trajectory for the target impedance model that is driven by the force error to produce command position. By following the command position trajectory the robotic manipulator can follow the unknown constraint surface while keeping an acceptable force error in a manner depicted by the target impedance model. Computer simulation on a 3 linked planar manipulator and experimental studies on an Adept 3, an SCARA type robotic manipulator, are conducted to verify the force tracking capability of the proposed control strategy.展开更多
AIM： To introduce a bioimpedance gastric motility mea- surement method based on an electrical-mechanical composite concept and a preliminary clinical application. METHODS： A noninvasive gastric motility measure- men...AIM： To introduce a bioimpedance gastric motility mea- surement method based on an electrical-mechanical composite concept and a preliminary clinical application. METHODS： A noninvasive gastric motility measure- ment method combining electrogastrograrn （EGG） and impedance gastric motility （IGM） test was used. Prelim- inary clinical application studies of patients with func- tional dyspepsia （FD） and gastritis, as well as healthy controls, were carried out. Twenty-eight FD patients （mean age 40.9±9.7 years） and 40 healthy volun- teers （mean age 30.9±7.9 years） were involved. IGM spectrum was measured for both the healthy subjects and FD patients, and outcomes were compared in the FD patients before treatment and 1 wk and 3 wk after treatment. IGM parameters were obtained from 30 erosive gastritis patients （mean age 50.5±13.0 years） and 40 healthy adults, and IGM and EGG results were compared in the gastritis patients before treatment and 1 wk after treatment.RESULTS： There were significant differences in the IGM parameters between the FD patients and healthy subjects, and FD patients had a poorer gastric motility [percentage of normal frequency （PNF） 70.8±25.5 in healthy subjects and 28.3 =t= 16.9 in FD patients, P 〈 0.01]. After 1 wk administration of domperidone 10 mg, tid, the gastric motility of FD patients was not im- proved, although the EGG of the patients had returned to normal. After 3 wk of treatment, the IGM rhythm of the FD patients became normal. There was a significant difference in IGM parameters between the two groups （PNF 70.4：1：25.5 for healthy subjects and 36.1 4- 21.8 for gastritis patients, P 〈 0.05）. The EGG rhythm of the gastritis patients returned to normal （frequency insta- bility coefficient 2.22±0.43 before treatment and 1.77 ：t： 0.19 one wk after treatment, P 〈 0.05） after 1 wk of treatment with sodium rabeprazole tablets, 10 mg, qd, po, qm, while some IGM parameters showed a tenden- cy toward improvement but had not reached statistical significance. CONCLUSION： The electrical-mechanical composite measurement method showed an attractive clinical appli- cation prospect in gastric motility research and evaluation.展开更多
In situ testing provides accurate characterization of existing degradation mechanisms of materials and building systems which helps reducing the subjectivity of visual inspections especially when ageing under natural ...In situ testing provides accurate characterization of existing degradation mechanisms of materials and building systems which helps reducing the subjectivity of visual inspections especially when ageing under natural ageing conditions is carried out over significant periods of time. In this work, data collected from field experimental campaigns over 10 years after construction using several premixed one-coat rendered walls and over 4 and 6 years after construction in the case of ETICS （external thermal insulation composite systems） are presented and discussed. The influence of hydrophobic agents on the performance of both types of facades in terms of surface condition and water penetration was assessed by visual inspections, Karsten test and capillary tests. Additionally, adhesion tests and subsequent evaluation of porosity were also carried out for premixed one-coat mortars. The results obtained have shown that ageing of the rendering solutions, especially after 5 or 6 years in-service, results from the loss of resistance to liquid water penetration, especially at the surface. Yet, additional mechanisms such as leaching of hydrophobic agents and photochemical degradation are thought to be involved, too. Moreover, the results obtained using the Karsten test proved to be the most reliable method to determine the loss of water penetration resistance and predict the ageing of facade solutions. The information collected and the correlations established can help developing solutions to prevent early ageing and implement appropriate maintenance plans to delay their effect.展开更多
This paper deals with various aspects of modeling, simulation, analysis, and control ofa SRG （switched reluctance generator） in different modes of operation. Excitation method of such a generator is shortly describe...This paper deals with various aspects of modeling, simulation, analysis, and control ofa SRG （switched reluctance generator） in different modes of operation. Excitation method of such a generator is shortly described. The output power of the SRG is controlled so that it can track the maximum output power of a wind turbine drive applications. Also, the output generator voltage is stabilized under either load or wind speed variations. Basic operational characteristics of a three-phase 6/4 SRG are developed through experimental observation. Meanwhile, the real-time operation was implemented in a DSP （digital signal processor） environment. The simulation of the complete system model has been obtained using the Matlab/Simulink software. A good agreement between experimental and simulation results has been observed which supports the validity of the proposed analysis.展开更多
In the present study, we propose a novel lift mechanism for which the lifting surface produces only lift. This is achieved by mounting a two-dimensional shock-shock interaction generator below the lifting surface. The...In the present study, we propose a novel lift mechanism for which the lifting surface produces only lift. This is achieved by mounting a two-dimensional shock-shock interaction generator below the lifting surface. The shock-shock interaction theory in conjunction with a three dimensional correction and checked with computational fluid dynamics (CFD) is used to analyze the lift and drag forces as function of the geometrical parameters and inflow Mach number. Through this study, though limited to only inviscid flow, we conclude that it is possible to obtain a high lift to drag ratio by suitably arranging the shock interaction generator.展开更多
文摘A force control strategy for position controlled robotic manipulators is presented. On line force feedback data are employed to estimate the local shape of the unknown constraint. The estimated vectors are used to generate the virtual reference trajectory for the target impedance model that is driven by the force error to produce command position. By following the command position trajectory the robotic manipulator can follow the unknown constraint surface while keeping an acceptable force error in a manner depicted by the target impedance model. Computer simulation on a 3 linked planar manipulator and experimental studies on an Adept 3, an SCARA type robotic manipulator, are conducted to verify the force tracking capability of the proposed control strategy.
基金Supported by The National Natural Science Foundation of China, No. 60471041 and 60901045
文摘AIM： To introduce a bioimpedance gastric motility mea- surement method based on an electrical-mechanical composite concept and a preliminary clinical application. METHODS： A noninvasive gastric motility measure- ment method combining electrogastrograrn （EGG） and impedance gastric motility （IGM） test was used. Prelim- inary clinical application studies of patients with func- tional dyspepsia （FD） and gastritis, as well as healthy controls, were carried out. Twenty-eight FD patients （mean age 40.9±9.7 years） and 40 healthy volun- teers （mean age 30.9±7.9 years） were involved. IGM spectrum was measured for both the healthy subjects and FD patients, and outcomes were compared in the FD patients before treatment and 1 wk and 3 wk after treatment. IGM parameters were obtained from 30 erosive gastritis patients （mean age 50.5±13.0 years） and 40 healthy adults, and IGM and EGG results were compared in the gastritis patients before treatment and 1 wk after treatment.RESULTS： There were significant differences in the IGM parameters between the FD patients and healthy subjects, and FD patients had a poorer gastric motility [percentage of normal frequency （PNF） 70.8±25.5 in healthy subjects and 28.3 =t= 16.9 in FD patients, P 〈 0.01]. After 1 wk administration of domperidone 10 mg, tid, the gastric motility of FD patients was not im- proved, although the EGG of the patients had returned to normal. After 3 wk of treatment, the IGM rhythm of the FD patients became normal. There was a significant difference in IGM parameters between the two groups （PNF 70.4：1：25.5 for healthy subjects and 36.1 4- 21.8 for gastritis patients, P 〈 0.05）. The EGG rhythm of the gastritis patients returned to normal （frequency insta- bility coefficient 2.22±0.43 before treatment and 1.77 ：t： 0.19 one wk after treatment, P 〈 0.05） after 1 wk of treatment with sodium rabeprazole tablets, 10 mg, qd, po, qm, while some IGM parameters showed a tenden- cy toward improvement but had not reached statistical significance. CONCLUSION： The electrical-mechanical composite measurement method showed an attractive clinical appli- cation prospect in gastric motility research and evaluation.
文摘In situ testing provides accurate characterization of existing degradation mechanisms of materials and building systems which helps reducing the subjectivity of visual inspections especially when ageing under natural ageing conditions is carried out over significant periods of time. In this work, data collected from field experimental campaigns over 10 years after construction using several premixed one-coat rendered walls and over 4 and 6 years after construction in the case of ETICS （external thermal insulation composite systems） are presented and discussed. The influence of hydrophobic agents on the performance of both types of facades in terms of surface condition and water penetration was assessed by visual inspections, Karsten test and capillary tests. Additionally, adhesion tests and subsequent evaluation of porosity were also carried out for premixed one-coat mortars. The results obtained have shown that ageing of the rendering solutions, especially after 5 or 6 years in-service, results from the loss of resistance to liquid water penetration, especially at the surface. Yet, additional mechanisms such as leaching of hydrophobic agents and photochemical degradation are thought to be involved, too. Moreover, the results obtained using the Karsten test proved to be the most reliable method to determine the loss of water penetration resistance and predict the ageing of facade solutions. The information collected and the correlations established can help developing solutions to prevent early ageing and implement appropriate maintenance plans to delay their effect.
文摘This paper deals with various aspects of modeling, simulation, analysis, and control ofa SRG （switched reluctance generator） in different modes of operation. Excitation method of such a generator is shortly described. The output power of the SRG is controlled so that it can track the maximum output power of a wind turbine drive applications. Also, the output generator voltage is stabilized under either load or wind speed variations. Basic operational characteristics of a three-phase 6/4 SRG are developed through experimental observation. Meanwhile, the real-time operation was implemented in a DSP （digital signal processor） environment. The simulation of the complete system model has been obtained using the Matlab/Simulink software. A good agreement between experimental and simulation results has been observed which supports the validity of the proposed analysis.
文摘In the present study, we propose a novel lift mechanism for which the lifting surface produces only lift. This is achieved by mounting a two-dimensional shock-shock interaction generator below the lifting surface. The shock-shock interaction theory in conjunction with a three dimensional correction and checked with computational fluid dynamics (CFD) is used to analyze the lift and drag forces as function of the geometrical parameters and inflow Mach number. Through this study, though limited to only inviscid flow, we conclude that it is possible to obtain a high lift to drag ratio by suitably arranging the shock interaction generator.
