A new experiment was made on the developing of bed separations and mining subsidence from Tangshan T2192 working face by equivalent materials simulation.The overburden deformation and the developing of bed separations...A new experiment was made on the developing of bed separations and mining subsidence from Tangshan T2192 working face by equivalent materials simulation.The overburden deformation and the developing of bed separations with working face advanc- ing was simulated by a new model.The results show that the maximum value of bed separations moved forward gradually along with the working face advancing;the maxi- mum value of bed separations is 0.31～0.50 times of mining thickness.The key strata have a great influence upon surface subsidence during the overburden movement process.The mechanics parameters of new experiment are fitted with results in fields perfectly.展开更多
An equivalent circuit model of a novel fence structure vibratory micromachined gy- roscope's oscillating properties is modeled by electrical equivalent circuits according to its dynamics equation.Equivalent circui...An equivalent circuit model of a novel fence structure vibratory micromachined gy- roscope's oscillating properties is modeled by electrical equivalent circuits according to its dynamics equation.Equivalent circuit model of oscillating and differential detection capacitance model are im- plemented in the circuit simulation tool PSPICE,which is available in oscillating properties analysis such as oscillating's transient response,steady response and frequency response to angular rate to op- timize working mode of the gyroscope.The model also enables sensor simulation with the interfacing electronics to analyse the performances of the whole system.Behavioral simulation of the system is performed to prove the function of detection circuits.The simulation results and measurement results show that the design of circuits is feasible.展开更多
The capacitively coupled radio frequency（CCRF）plasma has been widely used in various fields.In some cases,it requires us to estimate the range of key plasma parameters simpler and quicker in order to understand the ...The capacitively coupled radio frequency（CCRF）plasma has been widely used in various fields.In some cases,it requires us to estimate the range of key plasma parameters simpler and quicker in order to understand the behavior in plasma.In this paper,a glass vacuum chamber and a pair of plate electrodes were designed and fabricated,using 13.56 MHz radio frequency（RF）discharge technology to ionize the working gas of Ar.This discharge was mathematically described with equivalent circuit model.The discharge voltage and current of the plasma were measured atdifferent pressures and different powers.Based on the capacitively coupled homogeneous discharge model,the equivalent circuit and the analytical formula were established.The plasma density and temperature were calculated by using the equivalent impedance principle and energy balance equation.The experimental results show that when RF discharge power is 50–300 W and pressure is 25–250 Pa,the average electron temperature is about 1.7–2.1 e V and the average electron density is about 0.5？×10^17–3.6？×10^17m^-3.Agreement was found when the results were compared to those given by optical emission spectroscopy and COMSOL simulation.展开更多
The buckling formation and influence factors during welding thin - plated structures were investigated based on finite element methods, An engineering treatment method for prdicating the buckling distor- tion wa...The buckling formation and influence factors during welding thin - plated structures were investigated based on finite element methods, An engineering treatment method for prdicating the buckling distor- tion was proposed in here. It was used the equivalent applied thermal - load to simulate the welding residual stress,therefore the calculation of complex welding distoriton can be transformed into 3D elas- tic structural applied- load analyses, which can reduce the quantities of calculating works effectively. The validation of the method was verified by comparison of the numerical simulation and experimental results. The simulation of buckling distorition for side - walled structrues of paseenger train was per- formed and the calculation was in agreement with measuring results in general. It was shown that the main factors for producing the buckling were the intermittent fillet and ping the during welding the stiffened beams and columns to the panel.The existence of the free edge of panels would reduce the crit- ical buckling stress and enlarge the deflection obviously,but the continuous weld in closed frames didn' t degrade the buckling situation.展开更多
Point Sources and Gaussian beams are used frequently as fundamental building blocks for developing ultrasonic beam models. Both these models have different weaknesses that limit their effectiveness. Here, we will show...Point Sources and Gaussian beams are used frequently as fundamental building blocks for developing ultrasonic beam models. Both these models have different weaknesses that limit their effectiveness. Here, we will show that one can develop a Gaussian Beam Equivalent Point Source （GBEPS） model that removes those weaknesses and combines the accuracy and versatility of the point source models with much of the speed and well-behaved nature of Gaussian beam models. We will demonstrate the efficiency and versatility of this new GBEPS model in simulating the beams generated from ultrasonic phased arrays, using as few as one Gaussian beam per element of the array. A single element GBEPS model will be shown to be as accurate as a point source model even when substantial beam focusing or steering is present in the array or where the array beam is transmitted through an interface. At the same time the GBEPS model will be shown to be several orders of magnitude faster than the point source model.展开更多
This study explored the use of queue clearance rate method for estimating passenger car equivalent （PCE） at signalized intersections. PCE was estimated based on the assumption that the rate at which a queue of vehic...This study explored the use of queue clearance rate method for estimating passenger car equivalent （PCE） at signalized intersections. PCE was estimated based on the assumption that the rate at which a queue of vehicles clears the intersection is a function of its composition. Results of this method were compared with the results estimated by some popular techniques. A fourqegged intersection was simulated in VISSIM software and different techniques were used to convert the traffic mix into a uniform one. Parameters of VISSIM were modified to closely reflect the traffic behaviour under heterogeneous traffic conditions. All approaches of the intersection were loaded to saturated conditions and accuracy of estimated PCEs were established by comparing converted flow （PCE/h） with the capacity of an all-car traffic stream. Method based on saturation flow delivered the best result, but its use was limited to traffic composed only of two types of vehicles. Results of regression and optimization techniques were almost similar and the converted flow was close to the capacity of all-car stream. However, accuracy of these methods strongly relied on the correct measurement of saturation flow. Queue clearance rate method did not require value of saturation flow and yielded good estimates of PCE throughout the simu- lation runs. The maximum difference between the converted flow and capacity estimated with all car situations was found to be less than 10% in all cases considered in this study.展开更多
基金The National Natural Science Funds Committee(50174035)
文摘A new experiment was made on the developing of bed separations and mining subsidence from Tangshan T2192 working face by equivalent materials simulation.The overburden deformation and the developing of bed separations with working face advanc- ing was simulated by a new model.The results show that the maximum value of bed separations moved forward gradually along with the working face advancing;the maxi- mum value of bed separations is 0.31～0.50 times of mining thickness.The key strata have a great influence upon surface subsidence during the overburden movement process.The mechanics parameters of new experiment are fitted with results in fields perfectly.
基金The project supported by the Major State Basic Research Development Program "Integrated Micro-Optical-Electro-Mechanical System"(G1999033101)
文摘An equivalent circuit model of a novel fence structure vibratory micromachined gy- roscope's oscillating properties is modeled by electrical equivalent circuits according to its dynamics equation.Equivalent circuit model of oscillating and differential detection capacitance model are im- plemented in the circuit simulation tool PSPICE,which is available in oscillating properties analysis such as oscillating's transient response,steady response and frequency response to angular rate to op- timize working mode of the gyroscope.The model also enables sensor simulation with the interfacing electronics to analyse the performances of the whole system.Behavioral simulation of the system is performed to prove the function of detection circuits.The simulation results and measurement results show that the design of circuits is feasible.
基金supported by National Natural Science Foundation of China(Grant No.61378037)the Fundamental Research Funds for the Central Universities(Nos.2013B33614,2017B15214)+1 种基金the Research Funds of Innovation and Entrepreneurship Education Reform for Chinese Universities(No.16CCJG01Z004)the Changzhou Science and Technology Program(No.CJ20160027)
文摘The capacitively coupled radio frequency（CCRF）plasma has been widely used in various fields.In some cases,it requires us to estimate the range of key plasma parameters simpler and quicker in order to understand the behavior in plasma.In this paper,a glass vacuum chamber and a pair of plate electrodes were designed and fabricated,using 13.56 MHz radio frequency（RF）discharge technology to ionize the working gas of Ar.This discharge was mathematically described with equivalent circuit model.The discharge voltage and current of the plasma were measured atdifferent pressures and different powers.Based on the capacitively coupled homogeneous discharge model,the equivalent circuit and the analytical formula were established.The plasma density and temperature were calculated by using the equivalent impedance principle and energy balance equation.The experimental results show that when RF discharge power is 50–300 W and pressure is 25–250 Pa,the average electron temperature is about 1.7–2.1 e V and the average electron density is about 0.5？×10^17–3.6？×10^17m^-3.Agreement was found when the results were compared to those given by optical emission spectroscopy and COMSOL simulation.
文摘The buckling formation and influence factors during welding thin - plated structures were investigated based on finite element methods, An engineering treatment method for prdicating the buckling distor- tion was proposed in here. It was used the equivalent applied thermal - load to simulate the welding residual stress,therefore the calculation of complex welding distoriton can be transformed into 3D elas- tic structural applied- load analyses, which can reduce the quantities of calculating works effectively. The validation of the method was verified by comparison of the numerical simulation and experimental results. The simulation of buckling distorition for side - walled structrues of paseenger train was per- formed and the calculation was in agreement with measuring results in general. It was shown that the main factors for producing the buckling were the intermittent fillet and ping the during welding the stiffened beams and columns to the panel.The existence of the free edge of panels would reduce the crit- ical buckling stress and enlarge the deflection obviously,but the continuous weld in closed frames didn' t degrade the buckling situation.
基金supported by the National Science Foundation Industry/University Cooperative Research Center program at Iowa State Universitythe Natural Sciences and Engineering Research Council of Canadaby the National Natural Science Foundation of China(NSFC)
文摘Point Sources and Gaussian beams are used frequently as fundamental building blocks for developing ultrasonic beam models. Both these models have different weaknesses that limit their effectiveness. Here, we will show that one can develop a Gaussian Beam Equivalent Point Source （GBEPS） model that removes those weaknesses and combines the accuracy and versatility of the point source models with much of the speed and well-behaved nature of Gaussian beam models. We will demonstrate the efficiency and versatility of this new GBEPS model in simulating the beams generated from ultrasonic phased arrays, using as few as one Gaussian beam per element of the array. A single element GBEPS model will be shown to be as accurate as a point source model even when substantial beam focusing or steering is present in the array or where the array beam is transmitted through an interface. At the same time the GBEPS model will be shown to be several orders of magnitude faster than the point source model.
文摘This study explored the use of queue clearance rate method for estimating passenger car equivalent （PCE） at signalized intersections. PCE was estimated based on the assumption that the rate at which a queue of vehicles clears the intersection is a function of its composition. Results of this method were compared with the results estimated by some popular techniques. A fourqegged intersection was simulated in VISSIM software and different techniques were used to convert the traffic mix into a uniform one. Parameters of VISSIM were modified to closely reflect the traffic behaviour under heterogeneous traffic conditions. All approaches of the intersection were loaded to saturated conditions and accuracy of estimated PCEs were established by comparing converted flow （PCE/h） with the capacity of an all-car traffic stream. Method based on saturation flow delivered the best result, but its use was limited to traffic composed only of two types of vehicles. Results of regression and optimization techniques were almost similar and the converted flow was close to the capacity of all-car stream. However, accuracy of these methods strongly relied on the correct measurement of saturation flow. Queue clearance rate method did not require value of saturation flow and yielded good estimates of PCE throughout the simu- lation runs. The maximum difference between the converted flow and capacity estimated with all car situations was found to be less than 10% in all cases considered in this study.
