In this paper the present authors measured the gas-particle two-phase velocity correlation in sudden expansion gas-particle flows with a phase Doppler particle anemometer (PDPA) and simulated the system behavior by ...In this paper the present authors measured the gas-particle two-phase velocity correlation in sudden expansion gas-particle flows with a phase Doppler particle anemometer (PDPA) and simulated the system behavior by using both a Reynolds-averaged Navier-Stokes (RANS) model and a large-eddy simulation (LES). The results of the measurements yield the axial and radial time-averaged velocities as well as the fluctuation velocities of gas and three particle-size groups (30μm, 50μm, and 95μm) and the gasparticle velocity correlation for 30μm and 50μm particles. From the measurements, theoretical analysis, and simulation, it is found that the two-phase velocity correlation of sudden-expansion flows, like that of jet flows, is less than the gas and particle Reynolds stresses. What distinguishes the two-phase velocity correlations of sudden-expansion flow from those of jet and channel flows is the absence of a clear relationship between the two-phase velocity correlation and particle size in sudden-expansion flows. The measurements, theoretical analysis, and numerical simulation all lead to the above-stated conclusions. Quantitatively, the results of the LES are better than those of the RANS model.展开更多
Vehicle-to-Everything(V2X) communications will be an essential part of the technology in future autonomous drive decision systems.A fundamental procedure is to establish a robust communication channel between end-to-e...Vehicle-to-Everything(V2X) communications will be an essential part of the technology in future autonomous drive decision systems.A fundamental procedure is to establish a robust communication channel between end-to-end devices.Due to the antenna placed at different positions on vehicles,the existing cellular electro-magnetic(EM) wave propagation modelling does not fit properly for V2X direct communication application.In order to figure out a feasible understanding of this problem,this paper focuses on the propagation channel analysis in a rural Vehicle-to-Vehicle(V2V) scenario for vehicular communication with antenna position experiments at different heights.By adopting the ray-tracing algorithm,a rural scenario simulation model is built up via the use of a commercial-off-the-shelf(COTS) EM modelling software package,that computes the path loss received power and delay spread for a given propagation channel.Next,a real-world vehicle measurement campaign was performed to verify the simulation results.The simulated and measured receiver power was in good agreement with each other,and the results of this study considered two antenna types located at three different relative heights between the two vehicles.This research provides constructive guidance for the V2V antenna characteristics,antenna placement and vehicle communication channel analysis.展开更多
Macao Science Satellite-1(MSS-1)will be launched at the early of 2023 into a near-circular orbit.The mission is designed to measure the Earth’s geomagnetic field with unpreceded accuracy through a new perspective.The...Macao Science Satellite-1(MSS-1)will be launched at the early of 2023 into a near-circular orbit.The mission is designed to measure the Earth’s geomagnetic field with unpreceded accuracy through a new perspective.The most important component installed on the satellite,to ensure high accuracy,is the deployable boom(Optical Bench).A Vector Field Magnetometer(VFM),an Advanced Stellar Compass(ASC),and a Couple Dark State Magnetometers(CDSM)are deployed on the deployable boom.In order to maximize the mission’s scientific output,a numerical simulator on MSS-1’s deployable boom was required to evaluate the adaptability of all devices on the deployable boom and assist the satellite’s data pre-processing.This paper first briefly describes the synthesis of the Earth’s total magnetic field and then describes the method simulating the output of scalar and vector magnetometers.Finally,the calibration method is applied to the synthetic magnetometer data to analyze the possible noise/error of the relevant instruments.Our results show that the simulator can imitate the disturbance of different noise sources or errors in the measuring system,and is especially useful for the satellite’s data processing group.展开更多
Record-breaking high waves occurred during the passage of the typhoon Bolaven(1215)(TYB) in the East China Sea(ECS) and Yellow Sea(YS) although its intensity did not reach the level of a super typhoon.Winds an...Record-breaking high waves occurred during the passage of the typhoon Bolaven(1215)(TYB) in the East China Sea(ECS) and Yellow Sea(YS) although its intensity did not reach the level of a super typhoon.Winds and directional wave measurements were made using a range of in-situ instruments mounted on an ocean tower and buoys.In order to understand how such high waves with long duration occurred,analyses have been made through measurement and numerical simulations.TYB winds were generated using the TC96 typhoon wind model with the best track data calibrated with the measurements.And then the wind fields were blended with the reanalyzed synoptic-scale wind fields for a wave model.Wave fields were simulated using WAM4.5 with adjustment of C_d for gust of winds and bottom friction for the study area.Thus the accuracy of simulations is considerably enhanced,and the computed results are also in better agreement with measured data than before.It is found that the extremely high waves evolved as a result of the superposition of distant large swells and high wind seas generated by strong winds from the front/right quadrant of the typhoon track.As the typhoon moved at a speed a little slower than the dominant wave group velocity in a consistent direction for two days,the wave growth was significantly enhanced by strong wind input in an extended fetch and non-linear interaction.展开更多
In this work, a two-dimensional fluid model has been employed to study the characteristics of Ar/O2 radio frequency(RF) inductively coupled plasma discharges. The emphasis of this work has been put on the influence ...In this work, a two-dimensional fluid model has been employed to study the characteristics of Ar/O2 radio frequency(RF) inductively coupled plasma discharges. The emphasis of this work has been put on the influence of the external parameters(i.e., the RF power, the pressure, and the Ar/O2 gas ratio) on the plasma properties. The numerical results show that the RF power has a significant influence on the amplitude of the plasma density rather than on the spatial distribution.However, the pressure and the Ar/O2 gas ratio affect not only the amplitude of the plasma density, but also the spatial uniformity. Finally, the comparison between the simulation results and the experimental data has been made at different gas pressures and oxygen contents, and a good agreement has been achieved.展开更多
Background Currently,laser tracker is the primary instrument used to carry out three-dimensional position measurement in accelerator alignment.Theoretically,three-dimensional measuring data processed by three-dimensio...Background Currently,laser tracker is the primary instrument used to carry out three-dimensional position measurement in accelerator alignment.Theoretically,three-dimensional measuring data processed by three-dimensional adjustment are more rigorous,however,error accumulation is found in practice.Purpose In order to control error accumulation and further improve the measurement accuracy of accelerator alignment,this research introduces the laser alignment system into the activity of measurement and data processing.Methods A measurement scheme combining laser tracker and laser alignment system is proposed.To construct the constraint condition,the offset values from the measuring points to the laser straight-line datum were used.To carry out the three-dimensional adjustment with offset constraint,the laser tracker observations were used.Results A three-dimensional adjustment function model of laser tracker observations is given.The construction method of the constraint equation is researched,and the calculation formulas of the three-dimensional adjustment with offset constraint are derived.A 200 m linac tunnel control network is designed,using simulation measurement method,the measuring data of laser tracker and the offset values from the measuring points to the laser straight-line datum were generated.The simulated data are calculated by the method given in this paper and the result is analyzed.Conclusion Simulation result shows introducing the laser alignment system into laser tracker measurement and applying the three-dimensional adjustment with offset constraint can effectively suppress the error accumulation caused by long distance move station measurement.展开更多
基金supported by the National Natural Science Foundation of China (50606026 and 50736006)
文摘In this paper the present authors measured the gas-particle two-phase velocity correlation in sudden expansion gas-particle flows with a phase Doppler particle anemometer (PDPA) and simulated the system behavior by using both a Reynolds-averaged Navier-Stokes (RANS) model and a large-eddy simulation (LES). The results of the measurements yield the axial and radial time-averaged velocities as well as the fluctuation velocities of gas and three particle-size groups (30μm, 50μm, and 95μm) and the gasparticle velocity correlation for 30μm and 50μm particles. From the measurements, theoretical analysis, and simulation, it is found that the two-phase velocity correlation of sudden-expansion flows, like that of jet flows, is less than the gas and particle Reynolds stresses. What distinguishes the two-phase velocity correlations of sudden-expansion flow from those of jet and channel flows is the absence of a clear relationship between the two-phase velocity correlation and particle size in sudden-expansion flows. The measurements, theoretical analysis, and numerical simulation all lead to the above-stated conclusions. Quantitatively, the results of the LES are better than those of the RANS model.
文摘Vehicle-to-Everything(V2X) communications will be an essential part of the technology in future autonomous drive decision systems.A fundamental procedure is to establish a robust communication channel between end-to-end devices.Due to the antenna placed at different positions on vehicles,the existing cellular electro-magnetic(EM) wave propagation modelling does not fit properly for V2X direct communication application.In order to figure out a feasible understanding of this problem,this paper focuses on the propagation channel analysis in a rural Vehicle-to-Vehicle(V2V) scenario for vehicular communication with antenna position experiments at different heights.By adopting the ray-tracing algorithm,a rural scenario simulation model is built up via the use of a commercial-off-the-shelf(COTS) EM modelling software package,that computes the path loss received power and delay spread for a given propagation channel.Next,a real-world vehicle measurement campaign was performed to verify the simulation results.The simulated and measured receiver power was in good agreement with each other,and the results of this study considered two antenna types located at three different relative heights between the two vehicles.This research provides constructive guidance for the V2V antenna characteristics,antenna placement and vehicle communication channel analysis.
基金the B-type Strategic Priority Program of the Chinese Academy of Sciences(Grant No.XDB41000000)the China National Space Administration’s Pre-research Project on Civil Aerospace Technologies(Grant No.D020303)+2 种基金the Open Project Program of State Key Laboratory of Lunar and Planetary Sciences(Macao University of Science and Technology)through grant SKLLPS(MUST)-2021-2023the Shanghai 2022"Science and Technology Innovation Action Plan"Hong Kong,Macao,and Taiwan Science and Technology Cooperation Project with Grant No.22590760900 for giving the funding support to assist the authors to complete the work successfully。
文摘Macao Science Satellite-1(MSS-1)will be launched at the early of 2023 into a near-circular orbit.The mission is designed to measure the Earth’s geomagnetic field with unpreceded accuracy through a new perspective.The most important component installed on the satellite,to ensure high accuracy,is the deployable boom(Optical Bench).A Vector Field Magnetometer(VFM),an Advanced Stellar Compass(ASC),and a Couple Dark State Magnetometers(CDSM)are deployed on the deployable boom.In order to maximize the mission’s scientific output,a numerical simulator on MSS-1’s deployable boom was required to evaluate the adaptability of all devices on the deployable boom and assist the satellite’s data pre-processing.This paper first briefly describes the synthesis of the Earth’s total magnetic field and then describes the method simulating the output of scalar and vector magnetometers.Finally,the calibration method is applied to the synthetic magnetometer data to analyze the possible noise/error of the relevant instruments.Our results show that the simulator can imitate the disturbance of different noise sources or errors in the measuring system,and is especially useful for the satellite’s data processing group.
基金The Ministry of Oceans and Fisheries of Korea-"The Research and Development on Coastal Hydraulic Investigation of Busan New Port"and"Cooperative Project on Korea-China Bilateral Committee on Ocean Science"the Korea Institute of Ocean Science and Technology(KIOST)Project under contract No.PE99325+1 种基金the China-Korea Joint Ocean Research Center(CKJORC)-"Cooperation on the Development of Basic Technologies for the Yellow Sea and East China Sea Operational Oceanographic System(YOOS)"the Nuclear Safety Project of CKJORC and Major Project of KIOST under contract No.PE99304
文摘Record-breaking high waves occurred during the passage of the typhoon Bolaven(1215)(TYB) in the East China Sea(ECS) and Yellow Sea(YS) although its intensity did not reach the level of a super typhoon.Winds and directional wave measurements were made using a range of in-situ instruments mounted on an ocean tower and buoys.In order to understand how such high waves with long duration occurred,analyses have been made through measurement and numerical simulations.TYB winds were generated using the TC96 typhoon wind model with the best track data calibrated with the measurements.And then the wind fields were blended with the reanalyzed synoptic-scale wind fields for a wave model.Wave fields were simulated using WAM4.5 with adjustment of C_d for gust of winds and bottom friction for the study area.Thus the accuracy of simulations is considerably enhanced,and the computed results are also in better agreement with measured data than before.It is found that the extremely high waves evolved as a result of the superposition of distant large swells and high wind seas generated by strong winds from the front/right quadrant of the typhoon track.As the typhoon moved at a speed a little slower than the dominant wave group velocity in a consistent direction for two days,the wave growth was significantly enhanced by strong wind input in an extended fetch and non-linear interaction.
基金Project supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China(Grant No.2011ZX02403-001)the National Natural Science Foundation of China(Grant No.11205025)
文摘In this work, a two-dimensional fluid model has been employed to study the characteristics of Ar/O2 radio frequency(RF) inductively coupled plasma discharges. The emphasis of this work has been put on the influence of the external parameters(i.e., the RF power, the pressure, and the Ar/O2 gas ratio) on the plasma properties. The numerical results show that the RF power has a significant influence on the amplitude of the plasma density rather than on the spatial distribution.However, the pressure and the Ar/O2 gas ratio affect not only the amplitude of the plasma density, but also the spatial uniformity. Finally, the comparison between the simulation results and the experimental data has been made at different gas pressures and oxygen contents, and a good agreement has been achieved.
基金Funding was provided by Young Scientists Fund(Grant no.12075264).
文摘Background Currently,laser tracker is the primary instrument used to carry out three-dimensional position measurement in accelerator alignment.Theoretically,three-dimensional measuring data processed by three-dimensional adjustment are more rigorous,however,error accumulation is found in practice.Purpose In order to control error accumulation and further improve the measurement accuracy of accelerator alignment,this research introduces the laser alignment system into the activity of measurement and data processing.Methods A measurement scheme combining laser tracker and laser alignment system is proposed.To construct the constraint condition,the offset values from the measuring points to the laser straight-line datum were used.To carry out the three-dimensional adjustment with offset constraint,the laser tracker observations were used.Results A three-dimensional adjustment function model of laser tracker observations is given.The construction method of the constraint equation is researched,and the calculation formulas of the three-dimensional adjustment with offset constraint are derived.A 200 m linac tunnel control network is designed,using simulation measurement method,the measuring data of laser tracker and the offset values from the measuring points to the laser straight-line datum were generated.The simulated data are calculated by the method given in this paper and the result is analyzed.Conclusion Simulation result shows introducing the laser alignment system into laser tracker measurement and applying the three-dimensional adjustment with offset constraint can effectively suppress the error accumulation caused by long distance move station measurement.