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Gan, Chun,Wu, Jianhua,Yang, Shiyou Journal of International Conference on Electrical 2013 Journal of international Conference on Electrical Vol.2 No.3
Power converter plays a very important role in switched reluctance motor (SRM) systems, and it is also the easiest one to experience failures. Power converter faults will cause the motor to run in non equilibrium states, and a long time fault operation will lead to motor and other modules damaged, and make the system completely lose working stability. This paper uses an asymmetric bridge converter as the research object with three-phase SRM, employs the wavelet packet decomposition for the phase currents. It analyzes and studies the short circuit fault condition of IGBT, uses an energy discrete degree of the wavelet packet nodes as the fault characteristic, and conducts the corresponding experimental and simulation analysis to verify the effectiveness and practicality of the proposed method.
Chun-Lin Ye,Xuan-Gan Liu,Qi Huang,Xian-Liang Zhao 한국식품과학회 2013 Food Science and Biotechnology Vol.22 No.5
The molecular mechanism to induce apoptosis in human hepatoma SMMC-7721 cells was investigated using 2',4'-Dihydroxy-6'-methoxy-3',5'-dimethylchalcone (DMC) isolated from the buds of Cleistocalyx operculatus. Typical morphological changes in apoptotic body formation after DMC treatment were observed using acridine orange (AO)/ethidium bromide (EB) staining. After 48 h of incubation with 0, 6.25, 12.5, and 25 μM of DMC, the percentages of annexin V-FITC-positive/PI negative cells were 1.51, 9.33, 33.84, and 61.32%, respectively. Apoptosis induced by DMC was blocked by z-VAD-fmk, a caspase inhibitor. Analysis of fluorescence intensities of rhodamine 123 in cells showed that DMC induced a loss of mitochondrial membrane potential (ΔΨm). Western blot results showed that DMC decreased the Bcl-2/Bax ratio,suggesting that the Bcl-2 family is involved in control of apoptosis. All of these signal transduction pathways are involved in initiating apoptosis. DMC is a potential anticancer agent that deserves further exploration.
A proposed technique for determining aerodynamic pressures on residential homes
Tuan-Chun Fu,Arindam Gan Chowdhury,Aly Mousaad Aly,Girma Bitsuamlak,DongHun Yeo,Emil Simiu 한국풍공학회 2012 Wind and Structures, An International Journal (WAS Vol.15 No.1
Wind loads on low-rise buildings in general and residential homes in particular can differ significantly depending upon the laboratory in which they were measured. The differences are due in large part to inadequate simulations of the low-frequency content of atmospheric velocity fluctuations in the laboratory and to the small scale of the models used for the measurements. The imperfect spatial coherence of the low frequency velocity fluctuations results in reductions of the overall wind effects with respect to the case of perfectly coherent flows. For large buildings those reductions are significant. However, for buildings with sufficiently small dimensions (e.g., residential homes) the reductions are relatively small. A technique is proposed for simulating the effect of low-frequency flow fluctuations on such buildings more effectively from the point of view of testing accuracy and repeatability than is currently the case. Experimental results are presented that validate the proposed technique. The technique eliminates a major cause of discrepancies among measurements conducted in different laboratories. In addition, the technique allows the use of considerably larger model scales than are possible in conventional testing. This makes it possible to model architectural details, and improves Reynolds number similarity. The technique is applicable to wind tunnels and large scale open jet facilities, and can help to standardize flow simulations for testing residential homes as well as significantly improving testing accuracy and repeatability. The work reported in this paper is a first step in developing the proposed technique. Additional tests are planned to further refine the technique and test the range of its applicability.
Partial turbulence simulation and aerodynamic pressures validation for an open-jet testing facility
Tuan-Chun Fu,Arindam Gan Chowdhury,Girma Bitsuamlak,Thomas Baheru 한국풍공학회 2014 Wind and Structures, An International Journal (WAS Vol.19 No.1
This paper describes partial turbulence simulation and validation of the aerodynamic pressures on building models for an open-jet small-scale 12-Fan Wall of Wind (WOW) facility against their counterparts in a boundary-layer wind tunnel. The wind characteristics pertained to the Atmospheric Boundary Layer (ABL) mean wind speed profile and turbulent fluctuations simulated in the facility. Both in the wind tunnel and the small-scale 12-Fan WOW these wind characteristics were produced by using spires and roughness elements. It is emphasized in the paper that proper spectral density parameterization is required to simulate turbulent fluctuations correctly. Partial turbulence considering only high frequency part of the turbulent fluctuations spectrum was simulated in the small-scale 12-Fan WOW. For the validation of aerodynamic pressures a series of tests were conducted in both wind tunnel and the small-scale 12-fan WOW facilities on low-rise buildings including two gable roof and two hip roof buildings with two different slopes. Testing was performed to investigate the mean and peak pressure coefficients at various locations on the roofs including near the corners, edges, ridge and hip lines. The pressure coefficients comparisons showed that open-jet testing facility flows with partial simulations of ABL spectrum are capable of inducing pressures on low-rise buildings that reasonably agree with their boundary-layer wind tunnel counterparts.
A proposed technique for determining aerodynamic pressures on residential homes
Fu, Tuan-Chun,Aly, Aly Mousaad,Chowdhury, Arindam Gan,Bitsuamlak, Girma,Yeo, DongHun,Simiu, Emil Techno-Press 2012 Wind and Structures, An International Journal (WAS Vol.15 No.1
Wind loads on low-rise buildings in general and residential homes in particular can differ significantly depending upon the laboratory in which they were measured. The differences are due in large part to inadequate simulations of the low-frequency content of atmospheric velocity fluctuations in the laboratory and to the small scale of the models used for the measurements. The imperfect spatial coherence of the low frequency velocity fluctuations results in reductions of the overall wind effects with respect to the case of perfectly coherent flows. For large buildings those reductions are significant. However, for buildings with sufficiently small dimensions (e.g., residential homes) the reductions are relatively small. A technique is proposed for simulating the effect of low-frequency flow fluctuations on such buildings more effectively from the point of view of testing accuracy and repeatability than is currently the case. Experimental results are presented that validate the proposed technique. The technique eliminates a major cause of discrepancies among measurements conducted in different laboratories. In addition, the technique allows the use of considerably larger model scales than are possible in conventional testing. This makes it possible to model architectural details, and improves Reynolds number similarity. The technique is applicable to wind tunnels and large scale open jet facilities, and can help to standardize flow simulations for testing residential homes as well as significantly improving testing accuracy and repeatability. The work reported in this paper is a first step in developing the proposed technique. Additional tests are planned to further refine the technique and test the range of its applicability.
Partial turbulence simulation and aerodynamic pressures validation for an open-jet testing facility
Fu, Tuan-Chun,Chowdhury, Arindam Gan,Bitsuamlak, Girma,Baheru, Thomas Techno-Press 2014 Wind and Structures, An International Journal (WAS Vol.19 No.1
This paper describes partial turbulence simulation and validation of the aerodynamic pressures on building models for an open-jet small-scale 12-Fan Wall of Wind (WOW) facility against their counterparts in a boundary-layer wind tunnel. The wind characteristics pertained to the Atmospheric Boundary Layer (ABL) mean wind speed profile and turbulent fluctuations simulated in the facility. Both in the wind tunnel and the small-scale 12-Fan WOW these wind characteristics were produced by using spires and roughness elements. It is emphasized in the paper that proper spectral density parameterization is required to simulate turbulent fluctuations correctly. Partial turbulence considering only high frequency part of the turbulent fluctuations spectrum was simulated in the small-scale 12-Fan WOW. For the validation of aerodynamic pressures a series of tests were conducted in both wind tunnel and the small-scale 12-fan WOW facilities on low-rise buildings including two gable roof and two hip roof buildings with two different slopes. Testing was performed to investigate the mean and peak pressure coefficients at various locations on the roofs including near the corners, edges, ridge and hip lines. The pressure coefficients comparisons showed that open-jet testing facility flows with partial simulations of ABL spectrum are capable of inducing pressures on low-rise buildings that reasonably agree with their boundary-layer wind tunnel counterparts.