The problems associated with vibrations of viaducts and low-frequency structural noise radiation caused by train excitation continue to increase in importance.A new floating-slab track vibration isolator-non-obstructi...The problems associated with vibrations of viaducts and low-frequency structural noise radiation caused by train excitation continue to increase in importance.A new floating-slab track vibration isolator-non-obstructive particle damping-phononic crystal vibration isolator is proposed herein,which uses the particle damping vibration absorption technology and bandgap vibration control theory.The vibration reduction performance of the NOPD-PCVI was analyzed from the perspective of vibration control.The paper explores the structure-borne noise reduction performance of the NOPD-PCVIs installed on different bridge structures under varying service conditions encountered in practical engineering applications.The load transferred to the bridge is obtained from a coupled train-FST-bridge analytical model considering the different structural parameters of bridges.The vibration responses are obtained using the finite element method,while the structural noise radiation is simulated using the frequency-domain boundary element method.Using the particle swarm optimization algorithm,the parameters of the NOPD-PCVI are optimized so that its frequency bandgap matches the dominant bridge structural noise frequency range.The noise reduction performance of the NOPD-PCVIs is compared to the steel-spring isolation under different service conditions.展开更多
In order to enter effective parameters of rock mass in a numerical model,the relationships between mechanical parameters of rock and rock mass were obtained by an inversion method and an orthogonal test,given our meas...In order to enter effective parameters of rock mass in a numerical model,the relationships between mechanical parameters of rock and rock mass were obtained by an inversion method and an orthogonal test,given our measurements of the maximum heights of two failure zones in the Longdong coal mine. Using the maximum heights of the caving zone and the water-conducting fractured zone as test indices the modulus of elasticity,the Poisson ratio,cohesion and tension strength as test factors and different values of reduction enhancement factors as test levels,an orthogonal test was designed to obtain an optimum simulation scheme.From the analysis of different values of reduction enhancement factors which affect the test indices,an optimum factor combination for modification of parameters could be inferred.By using modified parameters in our numerical simulation,the maximum heights of the caving zone and the water-conducting fractured zone in the extensive Xiyi area were determined as 15.06 m and 36.92 m.These values were almost the same as those obtained by similar material simulation（8.5 m and 37.0 m）and empirical prediction（8.4 m and 34.4 m）.These results indicate that the modification of parameters is a rational method.展开更多
A high stabilized low dropout(LDO) voltage regulator fabricated for GPS radio frequency(RF) chip in SMIC 0.18μm CMOS technology is presented.The LDO mainly consists of bandgap reference,error amplifier,resistive feed...A high stabilized low dropout(LDO) voltage regulator fabricated for GPS radio frequency(RF) chip in SMIC 0.18μm CMOS technology is presented.The LDO mainly consists of bandgap reference,error amplifier,resistive feedback network and AC current path.A fast current path is added to improve the performance of LDO's transient response.Equivalent series resistance(ESR)compensation and internal Miller compensation are used to constitute the frequency compensation.The measurement results of the transient response of the output voltage show that it can recover within 2μs with less than 120 mV ripple when the load current is changed from 0 to 100 mA.The total quiescent current of LDO and bandgap reference(without load) is 260 μA.展开更多
A bandgap voltage reference is designed to meet the requirements of low power loss,low temperature coefficient and high power source rejection ratio(PSRR) in the intergrated circuit. Based on the analysis of conventio...A bandgap voltage reference is designed to meet the requirements of low power loss,low temperature coefficient and high power source rejection ratio(PSRR) in the intergrated circuit. Based on the analysis of conventional bandgap reference circuit,and combined with the integral performance of IC,the specific design index of the bandgap reference is put forward. In the meantime,the circuit and the layout are designed with Chartered 0.35 μm dual gate CMOS process. The simulation result shows that the coefficient is less than 30ppm/℃ with the temperature from -50 ℃ to 150 ℃. The bandgap reference has the characteristics of low power and high PSRR.展开更多
基金Project(51978585)supported by the National Natural Science Foundation,ChinaProject(2022YFB2603404)supported by the National Key Research and Development Program,China+1 种基金Project(U1734207)supported by the High-speed Rail Joint Fund Key Projects of Basic Research,ChinaProject(2023NSFSC1975)supported by the Sichuan Nature and Science Foundation Innovation Research Group Project,China。
文摘The problems associated with vibrations of viaducts and low-frequency structural noise radiation caused by train excitation continue to increase in importance.A new floating-slab track vibration isolator-non-obstructive particle damping-phononic crystal vibration isolator is proposed herein,which uses the particle damping vibration absorption technology and bandgap vibration control theory.The vibration reduction performance of the NOPD-PCVI was analyzed from the perspective of vibration control.The paper explores the structure-borne noise reduction performance of the NOPD-PCVIs installed on different bridge structures under varying service conditions encountered in practical engineering applications.The load transferred to the bridge is obtained from a coupled train-FST-bridge analytical model considering the different structural parameters of bridges.The vibration responses are obtained using the finite element method,while the structural noise radiation is simulated using the frequency-domain boundary element method.Using the particle swarm optimization algorithm,the parameters of the NOPD-PCVI are optimized so that its frequency bandgap matches the dominant bridge structural noise frequency range.The noise reduction performance of the NOPD-PCVIs is compared to the steel-spring isolation under different service conditions.
文摘In order to enter effective parameters of rock mass in a numerical model,the relationships between mechanical parameters of rock and rock mass were obtained by an inversion method and an orthogonal test,given our measurements of the maximum heights of two failure zones in the Longdong coal mine. Using the maximum heights of the caving zone and the water-conducting fractured zone as test indices the modulus of elasticity,the Poisson ratio,cohesion and tension strength as test factors and different values of reduction enhancement factors as test levels,an orthogonal test was designed to obtain an optimum simulation scheme.From the analysis of different values of reduction enhancement factors which affect the test indices,an optimum factor combination for modification of parameters could be inferred.By using modified parameters in our numerical simulation,the maximum heights of the caving zone and the water-conducting fractured zone in the extensive Xiyi area were determined as 15.06 m and 36.92 m.These values were almost the same as those obtained by similar material simulation（8.5 m and 37.0 m）and empirical prediction（8.4 m and 34.4 m）.These results indicate that the modification of parameters is a rational method.
基金Supported by the Communication Systems Project of Jiangsu Department(No.JHB04010)
文摘A high stabilized low dropout(LDO) voltage regulator fabricated for GPS radio frequency(RF) chip in SMIC 0.18μm CMOS technology is presented.The LDO mainly consists of bandgap reference,error amplifier,resistive feedback network and AC current path.A fast current path is added to improve the performance of LDO's transient response.Equivalent series resistance(ESR)compensation and internal Miller compensation are used to constitute the frequency compensation.The measurement results of the transient response of the output voltage show that it can recover within 2μs with less than 120 mV ripple when the load current is changed from 0 to 100 mA.The total quiescent current of LDO and bandgap reference(without load) is 260 μA.
文摘A bandgap voltage reference is designed to meet the requirements of low power loss,low temperature coefficient and high power source rejection ratio(PSRR) in the intergrated circuit. Based on the analysis of conventional bandgap reference circuit,and combined with the integral performance of IC,the specific design index of the bandgap reference is put forward. In the meantime,the circuit and the layout are designed with Chartered 0.35 μm dual gate CMOS process. The simulation result shows that the coefficient is less than 30ppm/℃ with the temperature from -50 ℃ to 150 ℃. The bandgap reference has the characteristics of low power and high PSRR.
