This paper reviews the development of forced motion apparatuses(FMAs) and their applications in wind engineering. A kind of FMA has been developed to investigate nonlinear and nonstationary aerodynamic forces consider...This paper reviews the development of forced motion apparatuses(FMAs) and their applications in wind engineering. A kind of FMA has been developed to investigate nonlinear and nonstationary aerodynamic forces considering the coupled effects of multiple degrees of freedom(DOFs). This apparatus can make section models to vibrate in a prescribed displacement defined by a numerical signal in time domain, including stationary and nonstationary movements with time-variant amplitudes and frequencies and even stochastic displacements. A series of validation tests show that the apparatus can re-illustrate various motions with enough precision in 3 D coupled states of two linear displacements and one torsional displacement. To meet the requirement of aerodynamic modeling, the flutter derivatives of a box girder section are identified, verifying its accuracy and feasibility by comparing with previously reported results. By simulating the nonstationary vibration with time-variant amplitude, the phenomena of frequency multiplication and memory effects are examined. In addition to studying the aerodynamics of a bluff body under large amplitudes and nonstationary vibrations, some potential applications of the proposed FMA are discussed in vehicle-bridge-wind dynamic analysis, pile-soil interaction, and line-tower coupled vibration aerodynamics in structural engineering.展开更多
The Brownian motion of a polystyrene bead trapped in a time-sharing optical tweezers （TSOT） is numerically simulated by adopting Monte-Carlo technique. By analyzing the Brownian motion signal, the effective stiffnes...The Brownian motion of a polystyrene bead trapped in a time-sharing optical tweezers （TSOT） is numerically simulated by adopting Monte-Carlo technique. By analyzing the Brownian motion signal, the effective stiffness of a TSOT is acquired at different switching frequencies. Simulation results confirm that for a specific laser power and duty ratio, the effective stiffness varies with the frequency at low frequency range, while at high frequency range it keeps constant. Our results reveal that the switching frequency can be used to control the stability of time-sharing optical tweezers in a range.展开更多
Objective： To study a non-drug therapy for hypertension disease by combining percutaneous laser and electric pulse stimulation to acupoint with music, and to test the efficiency of the combining treatment to grade 1 ...Objective： To study a non-drug therapy for hypertension disease by combining percutaneous laser and electric pulse stimulation to acupoint with music, and to test the efficiency of the combining treatment to grade 1 essential hypertension. Methods： A total of 174 patients with grade 1 essential hypertension were randomly assigned to 3 groups with a random number table after Chinese medicine（CM） syndrome differentiation： the photoelectric and musical treatment group（Group 1, with a self-developed multi-mode audio frequency pulse photoelectric therapeutic apparatus）, acupuncture group（Group 2）, and oral placebo group（Group 3）, 58 cases per group. The curative effect of each group was evaluated by the changes of blood pressure and CM syndrome integral before and after treatment. Results： Compared with Group 3, there were significant decrease of blood pressure and CM syndrome integral in Group 1 and Group 2（P〈0.01）. Compared with Group 2, Group 1 showed the highest decrease in systolic pressure（P〈0.017）. The total effective rate of anti-hypertension in Group 1（91.38%, 53/58） was significantly higher than that in Group 2（74.13%, 43/58） and Group 3（18.97%, 11/58, P〈0.05 or P〈0.01）; and that in Group 2 was also significantly higher than that in Group 3（P〈0.01）. There were significant difference in the total effective rate of CM syndrome integral in both Group 1（93.10%, 54/58） and Group 2（84.48%, 49/58） as compared with Group 3（17.24%, 10/58, P〈0.01）, while there was no significant difference between Group 1 and Group 2（P〉0.05）. Conclusions： The multi-mode audio frequency pulse photoelectric therapeutic apparatus, combining music, laser and electric pulse stimulation, is clinically useful for grade 1 essential hypertension. This ＂three in one＂ therapy method is non-invasive, easy and simple to handle. It is expected to be popularized as a new alternative treatment.展开更多
基金supported by the National Key Research and Development Program of China(Nos.2018YFC0809600 and 2018YFC0809604)the National Natural Science Foundation of China(No.51678451)the Independent Subject of State Key Laboratory of Disaster Reduction in Civil Engineering(No.SLDRCE19-B-11),Tongji University,China。
文摘This paper reviews the development of forced motion apparatuses(FMAs) and their applications in wind engineering. A kind of FMA has been developed to investigate nonlinear and nonstationary aerodynamic forces considering the coupled effects of multiple degrees of freedom(DOFs). This apparatus can make section models to vibrate in a prescribed displacement defined by a numerical signal in time domain, including stationary and nonstationary movements with time-variant amplitudes and frequencies and even stochastic displacements. A series of validation tests show that the apparatus can re-illustrate various motions with enough precision in 3 D coupled states of two linear displacements and one torsional displacement. To meet the requirement of aerodynamic modeling, the flutter derivatives of a box girder section are identified, verifying its accuracy and feasibility by comparing with previously reported results. By simulating the nonstationary vibration with time-variant amplitude, the phenomena of frequency multiplication and memory effects are examined. In addition to studying the aerodynamics of a bluff body under large amplitudes and nonstationary vibrations, some potential applications of the proposed FMA are discussed in vehicle-bridge-wind dynamic analysis, pile-soil interaction, and line-tower coupled vibration aerodynamics in structural engineering.
基金supported by the National"863"Project of China(Nos.2007AA021811 and 2007AA021809)the Funds of the Chinese Academy of Sciences for Key Topics in Innovation Engineering(No.KJCX2-YW-H-10)the Innovation Research Fund for Graduate Students of USTC.
文摘The Brownian motion of a polystyrene bead trapped in a time-sharing optical tweezers （TSOT） is numerically simulated by adopting Monte-Carlo technique. By analyzing the Brownian motion signal, the effective stiffness of a TSOT is acquired at different switching frequencies. Simulation results confirm that for a specific laser power and duty ratio, the effective stiffness varies with the frequency at low frequency range, while at high frequency range it keeps constant. Our results reveal that the switching frequency can be used to control the stability of time-sharing optical tweezers in a range.
基金Supported by the Research Project of Traditional Chinese Medicine Bureau of Guangdong Province,China(No.20111160)Science and Technology Plan of Guangdong Province,China(No.2009B030801162)
文摘Objective： To study a non-drug therapy for hypertension disease by combining percutaneous laser and electric pulse stimulation to acupoint with music, and to test the efficiency of the combining treatment to grade 1 essential hypertension. Methods： A total of 174 patients with grade 1 essential hypertension were randomly assigned to 3 groups with a random number table after Chinese medicine（CM） syndrome differentiation： the photoelectric and musical treatment group（Group 1, with a self-developed multi-mode audio frequency pulse photoelectric therapeutic apparatus）, acupuncture group（Group 2）, and oral placebo group（Group 3）, 58 cases per group. The curative effect of each group was evaluated by the changes of blood pressure and CM syndrome integral before and after treatment. Results： Compared with Group 3, there were significant decrease of blood pressure and CM syndrome integral in Group 1 and Group 2（P〈0.01）. Compared with Group 2, Group 1 showed the highest decrease in systolic pressure（P〈0.017）. The total effective rate of anti-hypertension in Group 1（91.38%, 53/58） was significantly higher than that in Group 2（74.13%, 43/58） and Group 3（18.97%, 11/58, P〈0.05 or P〈0.01）; and that in Group 2 was also significantly higher than that in Group 3（P〈0.01）. There were significant difference in the total effective rate of CM syndrome integral in both Group 1（93.10%, 54/58） and Group 2（84.48%, 49/58） as compared with Group 3（17.24%, 10/58, P〈0.01）, while there was no significant difference between Group 1 and Group 2（P〉0.05）. Conclusions： The multi-mode audio frequency pulse photoelectric therapeutic apparatus, combining music, laser and electric pulse stimulation, is clinically useful for grade 1 essential hypertension. This ＂three in one＂ therapy method is non-invasive, easy and simple to handle. It is expected to be popularized as a new alternative treatment.
