A new two-dimensional (2D) analytical model for the threshold-voltage of fully depleted SOI MOSFETs is derived. The 2D potential distribution functions in the active layer of the devices are obtained through solving...A new two-dimensional (2D) analytical model for the threshold-voltage of fully depleted SOI MOSFETs is derived. The 2D potential distribution functions in the active layer of the devices are obtained through solving the 2D Poisson's equation. The minimum of the potential at the oxide-Si layer interface is used to monitor the threshold voltage of the SOI MOSFETs. This model is verified by its excellent agreement with MEDICI simulation using SOI MOSFETs with different gate lengths,gate oxide thicknesses,silicon film thicknesses,and channel doping concentrations.展开更多
A novel approximation of the two-dimensional (2D) potential function perpendicular to the channel is proposed,and then an analytical threshold voltage model for a fully depleted SOI-MOSFET with a non-uniform Gaussia...A novel approximation of the two-dimensional (2D) potential function perpendicular to the channel is proposed,and then an analytical threshold voltage model for a fully depleted SOI-MOSFET with a non-uniform Gaussian distribution doping profile is given based on this approximation. The model agrees well with numerical simulation by MEDICI. The result represents a new way and some reference points in analyzing and controlling the threshold voltage of non-uniform fully depleted (FD) SOI devices in practice.展开更多
Purpose: This study aims to explore the effects of running on different surfaces on the characteristics of in-shoe plantar pressure and tibial acceleration. Methods: Thirteen male recreational runners were required ...Purpose: This study aims to explore the effects of running on different surfaces on the characteristics of in-shoe plantar pressure and tibial acceleration. Methods: Thirteen male recreational runners were required to run at 12 km/h velocity on concrete, synthetic track, natural grass, a normal treadmill, and a treadmill equipped with an ethylene vinyl acetate (EVA) cushioning underlay (treadmill_EVA), respectively. An in-shoe plantar pressure system and an accelerometer attached to the tibial tuberosity were used to record and analyze the characteristics of plantar pressure and tibial impact during running. Results: The results showed that there were no significant differences in the 1 st and 2nd peak plantar pressures (time of occurrence), pressure-time integral, and peak pressure distribution for the concrete, synthetic, grass, and normal treadmill surfaces. No significant differences in peak positive acceleration were observed among the five tested surface conditions. Compared to the concrete surface, however, running on treadmillEVA showed a significant decrease in the 1st peak plantar pressure and the pressure time integral for the impact phase (p 〈 0.05). These can be further ascribed to a reduced peak pressure observed at heel region (p 〈 0.05). Conclusion: There may not be an inevitable relationship between the surface and the lower-limb impact in runners. It is, however, still noteworthy that the effects of different treadmill surfaces should be considered in the interpretation of plantar pressure performance and translation of such results to overground running.展开更多
Mitigation of blast pressure using water in a walled container was evaluated. A PETN (pentaerythritol tetranitrate) pellet of 1.4 g near the model wall was detonated on a steel plate. A water-filled container was pl...Mitigation of blast pressure using water in a walled container was evaluated. A PETN (pentaerythritol tetranitrate) pellet of 1.4 g near the model wall was detonated on a steel plate. A water-filled container was placed between the explosive and the wall. The pressure histories at six points, which corresponded to Hopkinson scaled distance of from 3.6 m·kg^-1/3 to 21.7 m·kg^-1/3 were evaluated along with dependence of mitigation effects on the amount of water and the position of the container. The presence of the water and the wall mitigated the peak overpressure near the explosion points and the positive impulse along all points. The mitigation effect was equivalent to 20-30% reduction of explosive weight based on discussion of the equivalent ratio. The presence of the water along the wall (not very close to the explosive) also mitigated the blast pressure.展开更多
Analysis of the aerodynamic performance of high-speed trains in special cuts would provide references for the critical overturning velocity and complement the operation safety management under strong winds.This work w...Analysis of the aerodynamic performance of high-speed trains in special cuts would provide references for the critical overturning velocity and complement the operation safety management under strong winds.This work was conducted to investigate the flow structure around trains under different cut depths,slope angles using computational fluid dynamics(CFD).The high-speed train was considered with bogies and inter-carriage gaps.And the accuracy of the numerical method was validated by combining with the experimental data of wind tunnel tests.Then,the variations of aerodynamic forces and surface pressure distribution of the train were mainly analyzed.The results show that the surroundings of cuts along the railway line have a great effect on the crosswind stability of trains.With the slope angle and depth of the cut increasing,the coefficients of aerodynamic forces tend to reduce.An angle of 75°is chosen as the optimum one for the follow-up research.Under different depth conditions,the reasonable cut depth for high-speed trains to run safely is 3 m lower than that of the conventional cut whose slope ratio is 1:1.5.Furthermore,the windward slope angle is more important than the leeward one for the train aerodynamic performance.Due to the shield of appropriate cuts,the train body is in a minor positive pressure environment.Thus,designing a suitable cut can contribute to improving the operation safety of high-speed trains.展开更多
Top-contact organic field effect transistors(OFETs) based on poly(3-hexylthiophene)(P3HT) with different concentrations in chloroform(CHCl3) are fabricated.The output characteristics indicate that the P3HT concentrati...Top-contact organic field effect transistors(OFETs) based on poly(3-hexylthiophene)(P3HT) with different concentrations in chloroform(CHCl3) are fabricated.The output characteristics indicate that the P3HT concentration has significant influence on the OFET devices.The performance of the devices firstly is enhanced with increasing the P3HT concentration,and then decreases.The optimized devices with the P3HT concentration of 2 mg/mL show the best performance.The fieldeffect mobility is up to 1.4×10-2 cm2/Vs,the threshold voltage(Vt) is as low as-20 V,and the current on/off ratio(Ion/off) is close to the order of 104.The results suggest that the P3HT aggregation patterns induced by different concentrations can improve the performance of the OFETs.展开更多
文摘A new two-dimensional (2D) analytical model for the threshold-voltage of fully depleted SOI MOSFETs is derived. The 2D potential distribution functions in the active layer of the devices are obtained through solving the 2D Poisson's equation. The minimum of the potential at the oxide-Si layer interface is used to monitor the threshold voltage of the SOI MOSFETs. This model is verified by its excellent agreement with MEDICI simulation using SOI MOSFETs with different gate lengths,gate oxide thicknesses,silicon film thicknesses,and channel doping concentrations.
文摘A novel approximation of the two-dimensional (2D) potential function perpendicular to the channel is proposed,and then an analytical threshold voltage model for a fully depleted SOI-MOSFET with a non-uniform Gaussian distribution doping profile is given based on this approximation. The model agrees well with numerical simulation by MEDICI. The result represents a new way and some reference points in analyzing and controlling the threshold voltage of non-uniform fully depleted (FD) SOI devices in practice.
基金supported by the National Natural Science Foundation of China (No. 11302131, No. 11372194, No. 11572202)+4 种基金the Doctoral Fund of Ministry of Education of China (No. 20123156120003)the Innovation Program of Shanghai Municipal Education Commission (No. 14YZ125)the Science and Technology Commission of Shanghai Municipality (No. 14DZ1103500)
文摘Purpose: This study aims to explore the effects of running on different surfaces on the characteristics of in-shoe plantar pressure and tibial acceleration. Methods: Thirteen male recreational runners were required to run at 12 km/h velocity on concrete, synthetic track, natural grass, a normal treadmill, and a treadmill equipped with an ethylene vinyl acetate (EVA) cushioning underlay (treadmill_EVA), respectively. An in-shoe plantar pressure system and an accelerometer attached to the tibial tuberosity were used to record and analyze the characteristics of plantar pressure and tibial impact during running. Results: The results showed that there were no significant differences in the 1 st and 2nd peak plantar pressures (time of occurrence), pressure-time integral, and peak pressure distribution for the concrete, synthetic, grass, and normal treadmill surfaces. No significant differences in peak positive acceleration were observed among the five tested surface conditions. Compared to the concrete surface, however, running on treadmillEVA showed a significant decrease in the 1st peak plantar pressure and the pressure time integral for the impact phase (p 〈 0.05). These can be further ascribed to a reduced peak pressure observed at heel region (p 〈 0.05). Conclusion: There may not be an inevitable relationship between the surface and the lower-limb impact in runners. It is, however, still noteworthy that the effects of different treadmill surfaces should be considered in the interpretation of plantar pressure performance and translation of such results to overground running.
文摘Mitigation of blast pressure using water in a walled container was evaluated. A PETN (pentaerythritol tetranitrate) pellet of 1.4 g near the model wall was detonated on a steel plate. A water-filled container was placed between the explosive and the wall. The pressure histories at six points, which corresponded to Hopkinson scaled distance of from 3.6 m·kg^-1/3 to 21.7 m·kg^-1/3 were evaluated along with dependence of mitigation effects on the amount of water and the position of the container. The presence of the water and the wall mitigated the peak overpressure near the explosion points and the positive impulse along all points. The mitigation effect was equivalent to 20-30% reduction of explosive weight based on discussion of the equivalent ratio. The presence of the water along the wall (not very close to the explosive) also mitigated the blast pressure.
基金Projects(51075401,U1334205)supported by the National Natural Science Foundation of ChinaProject supported by the Scholarship Award for Excellent Innovative Doctoral Student granted by Central South University of ChinaProject(132014)supported by the Fok Ying Tong Education Foundation,China
文摘Analysis of the aerodynamic performance of high-speed trains in special cuts would provide references for the critical overturning velocity and complement the operation safety management under strong winds.This work was conducted to investigate the flow structure around trains under different cut depths,slope angles using computational fluid dynamics(CFD).The high-speed train was considered with bogies and inter-carriage gaps.And the accuracy of the numerical method was validated by combining with the experimental data of wind tunnel tests.Then,the variations of aerodynamic forces and surface pressure distribution of the train were mainly analyzed.The results show that the surroundings of cuts along the railway line have a great effect on the crosswind stability of trains.With the slope angle and depth of the cut increasing,the coefficients of aerodynamic forces tend to reduce.An angle of 75°is chosen as the optimum one for the follow-up research.Under different depth conditions,the reasonable cut depth for high-speed trains to run safely is 3 m lower than that of the conventional cut whose slope ratio is 1:1.5.Furthermore,the windward slope angle is more important than the leeward one for the train aerodynamic performance.Due to the shield of appropriate cuts,the train body is in a minor positive pressure environment.Thus,designing a suitable cut can contribute to improving the operation safety of high-speed trains.
基金supported by the National Natural Science Foundation of China (No.60676051)the Natural Science Fund of Tianjin (No.07JCYBJC12700)the Fund of Key Discipline of Material Physics and Chemistry of Tianjin
文摘Top-contact organic field effect transistors(OFETs) based on poly(3-hexylthiophene)(P3HT) with different concentrations in chloroform(CHCl3) are fabricated.The output characteristics indicate that the P3HT concentration has significant influence on the OFET devices.The performance of the devices firstly is enhanced with increasing the P3HT concentration,and then decreases.The optimized devices with the P3HT concentration of 2 mg/mL show the best performance.The fieldeffect mobility is up to 1.4×10-2 cm2/Vs,the threshold voltage(Vt) is as low as-20 V,and the current on/off ratio(Ion/off) is close to the order of 104.The results suggest that the P3HT aggregation patterns induced by different concentrations can improve the performance of the OFETs.