The 13-MeV proton linac of the Compact Pulsed Hadron Source(CPHS) at Tsinghua University, China,is composed of a 50-keV electron cyclotron resonance proton source, a 3-MeV four-vane-type radio-frequency quadrupole(RFQ...The 13-MeV proton linac of the Compact Pulsed Hadron Source(CPHS) at Tsinghua University, China,is composed of a 50-keV electron cyclotron resonance proton source, a 3-MeV four-vane-type radio-frequency quadrupole(RFQ) accelerator, and a drift tube linac(DTL). Precise measurement of the beam energies at the exit of the RFQ and the DTL is critical for DTL commissioning. Two button-type beam position monitors(BPMs) installed downstream of the RFQ are used to perform the measurement using a time-of-flight method. The effects of several factors on phase measurement accuracy are analyzed. The phase measurement accuracy of the BPMs at CPHS is better than ± 1.03° at 325 MHz after corrections,corresponding to an energy measurement error of± 0.07%. The beam energy measured at the exit of the RFQ is 2.994 ± 0.0022 MeV,which is consistent with the design value.展开更多
The vehicle routing problem(VRP) is a well-known combinatorial optimization issue in transportation and logistics network systems. There exist several limitations associated with the traditional VRP. Releasing the res...The vehicle routing problem(VRP) is a well-known combinatorial optimization issue in transportation and logistics network systems. There exist several limitations associated with the traditional VRP. Releasing the restricted conditions of traditional VRP has become a research focus in the past few decades. The vehicle routing problem with split deliveries and pickups(VRPSPDP) is particularly proposed to release the constraints on the visiting times per customer and vehicle capacity, that is, to allow the deliveries and pickups for each customer to be simultaneously split more than once. Few studies have focused on the VRPSPDP problem. In this paper we propose a two-stage heuristic method integrating the initial heuristic algorithm and hybrid heuristic algorithm to study the VRPSPDP problem. To validate the proposed algorithm, Solomon benchmark datasets and extended Solomon benchmark datasets were modified to compare with three other popular algorithms. A total of 18 datasets were used to evaluate the effectiveness of the proposed method. The computational results indicated that the proposed algorithm is superior to these three algorithms for VRPSPDP in terms of total travel cost and average loading rate.展开更多
This paper addresses the Multi-Vehicle Routing Problem with Time Windows and Simultaneous Pickup and Delivery(MVRPTWSPD),aiming to optimize logistics distribution routes and minimize total costs.A vehicle routing opti...This paper addresses the Multi-Vehicle Routing Problem with Time Windows and Simultaneous Pickup and Delivery(MVRPTWSPD),aiming to optimize logistics distribution routes and minimize total costs.A vehicle routing optimization model is developed based on the operational requirements of the KS Logistics Center,focusing on minimizing vehicle dispatch,loading and unloading,operating,and time window penalty costs.The model incorporates constraints such as vehicle capacity,time windows,and travel distance,and is solved using a genetic algorithm to ensure optimal route planning.Through MATLAB simulations,34 customer points are analyzed,demonstrating that the simultaneous pickup and delivery model reduces total costs by 30.13%,increases vehicle loading rates by 20.04%,and decreases travel distance compared to delivery-only or pickup-only models.The results demonstrate the significant advantages of the simultaneous pickup and delivery mode in reducing logistics costs and improving vehicle utilization,offering valuable insights for enhancing the operational efficiency of the KS Logistics Center.展开更多
Dynamic exclusive pickup and delivery problem with time windows (DE-PDPTW), aspecial dynamic vehicle scheduling problem, is proposed. Its mathematical description is given andits static properties are analyzed, and th...Dynamic exclusive pickup and delivery problem with time windows (DE-PDPTW), aspecial dynamic vehicle scheduling problem, is proposed. Its mathematical description is given andits static properties are analyzed, and then the problem is simplified asthe asymmetrical travelingsalesman problem with time windows. The rolling horizon scheduling algorithm (RHSA) to solve thisdynamic problem is proposed. By the rolling of time horizon, the RHSA can adapt to the problem'sdynamic change and reduce the computation time by dealing with only part of the customers in eachrolling time horizon. Then, its three factors, the current customer window, the scheduling of thecurrent customer window and the rolling strategy, are analyzed. The test results demonstrate theeffectiveness of the RHSA to solve the dynamic vehicle scheduling problem.展开更多
A new type of vehicle routing problem （VRP）, multiple vehicle routing problem integrated reverse logistics （MVRPRL）, is studied. In this problem, there is delivery or pickup （or both） and uncertain features in t...A new type of vehicle routing problem （VRP）, multiple vehicle routing problem integrated reverse logistics （MVRPRL）, is studied. In this problem, there is delivery or pickup （or both） and uncertain features in the demands of the clients. The deliveries of every client as uncertain parameters are expressed as triangular fuzzy numbers. In order to describe MVRPRL, a multi-objective fuzzy programming model with credibility measure theory is constructed. Then the simulationbased tabu search algorithm combining inter-route and intra-route neighborhoods and embedded restarts are designed to solve it. Computational results show that the tabu search algorithm developed is superior to sweep algorithms and that compared with handling each on separate routes, the transportation costs can be reduced by 43% through combining pickups with deliveries.展开更多
Indirect methods to detect and evaluate inclusions in steel are extensively reviewed, which include total oxygen content measurement, nitrogen pickup, steel and slag composition measurement, lining refractory observat...Indirect methods to detect and evaluate inclusions in steel are extensively reviewed, which include total oxygen content measurement, nitrogen pickup, steel and slag composition measurement, lining refractory observation, tracer studies of determining exogenous inclusions from slag and lining erosion, SEN clogging and final prod- uct tests. There is no single ideal method of detecting and evaluating inclusions in steel, so it is better to use several methods simultaneously to give a more accurate evaluation. Total oxygen content and nitrogen pickup in low carbon aluminum-killed steel as criterion of clean steel in many plants are summarized.展开更多
The weapon transportation support scheduling problem on aircraft carrier deck is the key to restricting the sortie rate and combat capability of carrier-based aircraft.This paper studies the problem and presents a nov...The weapon transportation support scheduling problem on aircraft carrier deck is the key to restricting the sortie rate and combat capability of carrier-based aircraft.This paper studies the problem and presents a novel solution architecture.Taking the interference of the carrier-based aircraft deck layout on the weapon transportation route and precedence constraint into consideration,a mixed integer formulation is established to minimize the total objective,which is constituted of makespan,load variance and accumulative transfer time of support unit.Solution approach is developed for the model.Firstly,based on modeling the carrier aircraft parked on deck as convex obstacles,the path library of weapon transportation is constructed through visibility graph and Warshall-Floyd methods.We then propose a bi-population immune algorithm in which a population-based forward/backward scheduling technique,local search schemes and a chaotic catastrophe operator are embedded.Besides,the randomkey solution representation and serial scheduling generation scheme are adopted to conveniently obtain a better solution.The Taguchi method is additionally employed to determine key parameters of the algorithm.Finally,on a set of generated realistic instances,we demonstrate that the proposed algorithm outperforms all compared algorithms designed for similar optimization problems and can significantly improve the efficiency,and that the established model and the bi-population immune algorithm can effectively respond to the weapon support requirements of carrier-based aircraft under different sortie missions.展开更多
In this paper, a hybrid genetic algorithm （GA） is proposed for the traveling salesman problem （TSP） with pickup and delivery （TSPPD）. In our algorithm, a novel pheromone-based crossover operator is advanced that...In this paper, a hybrid genetic algorithm （GA） is proposed for the traveling salesman problem （TSP） with pickup and delivery （TSPPD）. In our algorithm, a novel pheromone-based crossover operator is advanced that utilizes both local and global information to construct offspring. In addition, a local search procedure is integrated into the GA to accelerate convergence. The proposed GA has been tested on benchmark instances, and the computational results show that it gives better convergence than existing heuristics.展开更多
The multitrip pickup and delivery problem with time windows and manpower planning(MTPDPTW-MP)determines a set of ambulance routes and finds staff assignment for a hospital. It involves different stakeholders with dive...The multitrip pickup and delivery problem with time windows and manpower planning(MTPDPTW-MP)determines a set of ambulance routes and finds staff assignment for a hospital. It involves different stakeholders with diverse interests and objectives. This study firstly introduces a multiobjective MTPDPTW-MP(MO-MTPDPTWMP) with three objectives to better describe the real-world scenario. A multiobjective iterated local search algorithm with adaptive neighborhood selection(MOILS-ANS) is proposed to solve the problem. MOILS-ANS can generate a diverse set of alternative solutions for decision makers to meet their requirements. To better explore the search space, problem-specific neighborhood structures and an adaptive neighborhood selection strategy are carefully designed in MOILS-ANS. Experimental results show that the proposed MOILS-ANS significantly outperforms the other two multiobjective algorithms. Besides, the nature of objective functions and the properties of the problem are analyzed. Finally, the proposed MOILS-ANS is compared with the previous single-objective algorithm and the benefits of multiobjective optimization are discussed.展开更多
Thermal spray coatings have been widely used on hearth rolls in a continuous annealing line to improve steel sheet quality and prolong the roll service life. One of the common defects formed on a working hearth roll i...Thermal spray coatings have been widely used on hearth rolls in a continuous annealing line to improve steel sheet quality and prolong the roll service life. One of the common defects formed on a working hearth roll is the oxide pickup. The most common cause of the pickup formation is that the active Mn oxide reacts with coating. The potentials of two different coatings, CoCrAlYTa-Al2O3 (No. 1) and CoCrYNi-Y2O3 (No. 2), to duplicate pickups by reacting with Fe and Mn oxides were studied. There are three stages during pickup producing and growing. No. 2 coating effectively reduced the corrosion of Mn oxide. The characterization and modification of the surface oxide formed can be changed with different dew points. The results indicate that the dew point from — 53 to — 10 ℃ can change the depth of Mn oxide, such that an alteration can prevent the first stage and second stage and is good for preventing the pickup growing.展开更多
To occupy a greater market share in terminal distribution, companies are urged to make full use of cooperative coverage formed with brand effect and information sharing in the layout of pickup points. Based on the div...To occupy a greater market share in terminal distribution, companies are urged to make full use of cooperative coverage formed with brand effect and information sharing in the layout of pickup points. Based on the diversity of pickup points, the piecewise function, signal intensity function and probability function are introduced. Meanwhile, considering the effect of distance satisfaction and cooperation coverage on customer behavior, the location model of the pickup point under competitive environments is established. The genetic algorithm is used to solve the problem, and the effectiveness of the model and algorithm is verified by a case. The results show that the sensitivity of weighted demand coverages to budget decreases gradually. The maximum weighted demand coverage increases at first and then decreases with the increase of the signal threshold, and there is a positive correlation with the change of the actual demand coverage to the senior customers, but it is negatively related to the intermediate and primary customers. When the number of high-level pickup points in a competitive enterprise is small, the advantage of the target enterprise is more significant. Through comparison, the cooperative coverage model is better than the non-cooperative coverage model, in terms of the weighted demand coverage, the construction cost and the attention paid to the important customers.展开更多
Accurate measurement of the transverse position of a beam is crucial in particle accelerators because it plays a key role in determining the beam parameters.Existing methods for beam-position measurement rely on the d...Accurate measurement of the transverse position of a beam is crucial in particle accelerators because it plays a key role in determining the beam parameters.Existing methods for beam-position measurement rely on the detection of image currents induced on electrodes or narrow-band wake field induced by a beam passing through a cavity-type structure.However,these methods have limitations.The indirect measurement of multiple parameters is computationally complex,requiring external calibration to determine the system parameters in advance.Furthermore,the utilization of the beam signal information is incomplete.Hence,this study proposes a novel method for measuring the absolute electron beam transverse position.By utilizing the geometric relationship between the center position of the measured electron beam and multiple detection electrodes and by analyzing the differences in the arrival times of the beam signals detected by these electrodes,the absolute transverse position of the electron beam crossing the electrode plane can be calculated.This method features absolute position measurement,a position sensitivity coefficient independent of vacuum chamber apertures,and no requirement for a symmetrical detector electrode layout.The feasibility of this method is validated through numerical simulations and beam experiments.展开更多
The nuclear charge pickup cross sections of 84Kr on CH2,C,and Al targets are investigated using CR-39 nuclear track detector at the highest energy of 395 MeV/u.The cross sections for H are calculated from those measur...The nuclear charge pickup cross sections of 84Kr on CH2,C,and Al targets are investigated using CR-39 nuclear track detector at the highest energy of 395 MeV/u.The cross sections for H are calculated from those measured on C and CH2 targets.The dependence of the charge pickup cross section on target mass is studied.展开更多
In order to improve the dust absorption performance of the reverse blowing pickup mouth, the gas-solid flow motion properties inside the reverse blowing pickup mouth were simulated by using computational fluid dynamic...In order to improve the dust absorption performance of the reverse blowing pickup mouth, the gas-solid flow motion properties inside the reverse blowing pickup mouth were simulated by using computational fluid dynamics( CFD) software,Fluent.The results show that both the front baffle inclination angle and the pressure drop across the pickup mouth have significant impacts on dust absorption performance. As the inclination angle is increased,there is an increase in the overall and grade removal efficiency. As the front baffle inclination angle or pressure drop is increased,there is an increase in the overall and grade removal efficiencies.However,pressure drop affects energy consumption. Front baffle inclination angle and pressure drop are optimized. Optimal inclination angle and pressure drop are 105° and 2 300 Pa respectively. Sample machine is made and measured,which further verifies the appropriateness of numerical simulation and practicability of optimum strategy.展开更多
Ion pickup by a monochromatic low-frequency Alfv6n wave, which propagates along the background magnetic field, has recently been investigated in a low beta plasma （Lu and Li 2007 Phys. Plasmas 14 042303）. In this pa...Ion pickup by a monochromatic low-frequency Alfv6n wave, which propagates along the background magnetic field, has recently been investigated in a low beta plasma （Lu and Li 2007 Phys. Plasmas 14 042303）. In this paper, the monochromatic Alfven wave is generalized to a spectrum of Alfven waves with random phase. It finds that the process of ion pickup can be divided into two stages. First, ions are picked up in the transverse direction, and then phase difference （randomization） between ions due to their different parallel thermal motions leads to heating of the ions. The heating is dominant in the direction perpendicular to the background magnetic field. The temperatures of the ions at the asymptotic stage do not depend on individual waves in the spectrum, but are determined by the total amplitude of the waves. The effect of the initial ion bulk flow in the parallel direction on the heating is also considered in this paper.展开更多
This paper explained the mechanism of carbon pickup by ultra low carbon steels during continuous casting and indicated that the major cause of carbon pickup is the contact of the molten steel with the enriched carb...This paper explained the mechanism of carbon pickup by ultra low carbon steels during continuous casting and indicated that the major cause of carbon pickup is the contact of the molten steel with the enriched carbon layer of the powder. Forming of the enriched carbon layer is due to the existing of “carbon core”. Accordingly, the measures to reduce the carbon content and amount of the enriched carbon layer were investigated. A kind of new powder has been developed and successfully used to minimize the carbon pickup by ultra low carbon steels during continuous casting.展开更多
文摘The 13-MeV proton linac of the Compact Pulsed Hadron Source(CPHS) at Tsinghua University, China,is composed of a 50-keV electron cyclotron resonance proton source, a 3-MeV four-vane-type radio-frequency quadrupole(RFQ) accelerator, and a drift tube linac(DTL). Precise measurement of the beam energies at the exit of the RFQ and the DTL is critical for DTL commissioning. Two button-type beam position monitors(BPMs) installed downstream of the RFQ are used to perform the measurement using a time-of-flight method. The effects of several factors on phase measurement accuracy are analyzed. The phase measurement accuracy of the BPMs at CPHS is better than ± 1.03° at 325 MHz after corrections,corresponding to an energy measurement error of± 0.07%. The beam energy measured at the exit of the RFQ is 2.994 ± 0.0022 MeV,which is consistent with the design value.
基金Project supported by the National Natural Science Foundation of China(No.51138003)the National Social Science Foundation of Chongqing of China(No.2013YBJJ035)
文摘The vehicle routing problem(VRP) is a well-known combinatorial optimization issue in transportation and logistics network systems. There exist several limitations associated with the traditional VRP. Releasing the restricted conditions of traditional VRP has become a research focus in the past few decades. The vehicle routing problem with split deliveries and pickups(VRPSPDP) is particularly proposed to release the constraints on the visiting times per customer and vehicle capacity, that is, to allow the deliveries and pickups for each customer to be simultaneously split more than once. Few studies have focused on the VRPSPDP problem. In this paper we propose a two-stage heuristic method integrating the initial heuristic algorithm and hybrid heuristic algorithm to study the VRPSPDP problem. To validate the proposed algorithm, Solomon benchmark datasets and extended Solomon benchmark datasets were modified to compare with three other popular algorithms. A total of 18 datasets were used to evaluate the effectiveness of the proposed method. The computational results indicated that the proposed algorithm is superior to these three algorithms for VRPSPDP in terms of total travel cost and average loading rate.
文摘This paper addresses the Multi-Vehicle Routing Problem with Time Windows and Simultaneous Pickup and Delivery(MVRPTWSPD),aiming to optimize logistics distribution routes and minimize total costs.A vehicle routing optimization model is developed based on the operational requirements of the KS Logistics Center,focusing on minimizing vehicle dispatch,loading and unloading,operating,and time window penalty costs.The model incorporates constraints such as vehicle capacity,time windows,and travel distance,and is solved using a genetic algorithm to ensure optimal route planning.Through MATLAB simulations,34 customer points are analyzed,demonstrating that the simultaneous pickup and delivery model reduces total costs by 30.13%,increases vehicle loading rates by 20.04%,and decreases travel distance compared to delivery-only or pickup-only models.The results demonstrate the significant advantages of the simultaneous pickup and delivery mode in reducing logistics costs and improving vehicle utilization,offering valuable insights for enhancing the operational efficiency of the KS Logistics Center.
文摘Dynamic exclusive pickup and delivery problem with time windows (DE-PDPTW), aspecial dynamic vehicle scheduling problem, is proposed. Its mathematical description is given andits static properties are analyzed, and then the problem is simplified asthe asymmetrical travelingsalesman problem with time windows. The rolling horizon scheduling algorithm (RHSA) to solve thisdynamic problem is proposed. By the rolling of time horizon, the RHSA can adapt to the problem'sdynamic change and reduce the computation time by dealing with only part of the customers in eachrolling time horizon. Then, its three factors, the current customer window, the scheduling of thecurrent customer window and the rolling strategy, are analyzed. The test results demonstrate theeffectiveness of the RHSA to solve the dynamic vehicle scheduling problem.
基金The National Natural Science Foundation of China(No.70772059)Youth Science and Technology Innovation Foundation of Nanjing Agriculture University(No.KJ06029)
文摘A new type of vehicle routing problem （VRP）, multiple vehicle routing problem integrated reverse logistics （MVRPRL）, is studied. In this problem, there is delivery or pickup （or both） and uncertain features in the demands of the clients. The deliveries of every client as uncertain parameters are expressed as triangular fuzzy numbers. In order to describe MVRPRL, a multi-objective fuzzy programming model with credibility measure theory is constructed. Then the simulationbased tabu search algorithm combining inter-route and intra-route neighborhoods and embedded restarts are designed to solve it. Computational results show that the tabu search algorithm developed is superior to sweep algorithms and that compared with handling each on separate routes, the transportation costs can be reduced by 43% through combining pickups with deliveries.
文摘Indirect methods to detect and evaluate inclusions in steel are extensively reviewed, which include total oxygen content measurement, nitrogen pickup, steel and slag composition measurement, lining refractory observation, tracer studies of determining exogenous inclusions from slag and lining erosion, SEN clogging and final prod- uct tests. There is no single ideal method of detecting and evaluating inclusions in steel, so it is better to use several methods simultaneously to give a more accurate evaluation. Total oxygen content and nitrogen pickup in low carbon aluminum-killed steel as criterion of clean steel in many plants are summarized.
基金the financial support of the National Natural Science Foundation of China(No.52102453)。
文摘The weapon transportation support scheduling problem on aircraft carrier deck is the key to restricting the sortie rate and combat capability of carrier-based aircraft.This paper studies the problem and presents a novel solution architecture.Taking the interference of the carrier-based aircraft deck layout on the weapon transportation route and precedence constraint into consideration,a mixed integer formulation is established to minimize the total objective,which is constituted of makespan,load variance and accumulative transfer time of support unit.Solution approach is developed for the model.Firstly,based on modeling the carrier aircraft parked on deck as convex obstacles,the path library of weapon transportation is constructed through visibility graph and Warshall-Floyd methods.We then propose a bi-population immune algorithm in which a population-based forward/backward scheduling technique,local search schemes and a chaotic catastrophe operator are embedded.Besides,the randomkey solution representation and serial scheduling generation scheme are adopted to conveniently obtain a better solution.The Taguchi method is additionally employed to determine key parameters of the algorithm.Finally,on a set of generated realistic instances,we demonstrate that the proposed algorithm outperforms all compared algorithms designed for similar optimization problems and can significantly improve the efficiency,and that the established model and the bi-population immune algorithm can effectively respond to the weapon support requirements of carrier-based aircraft under different sortie missions.
文摘In this paper, a hybrid genetic algorithm （GA） is proposed for the traveling salesman problem （TSP） with pickup and delivery （TSPPD）. In our algorithm, a novel pheromone-based crossover operator is advanced that utilizes both local and global information to construct offspring. In addition, a local search procedure is integrated into the GA to accelerate convergence. The proposed GA has been tested on benchmark instances, and the computational results show that it gives better convergence than existing heuristics.
基金supported by the National Key R&D Program of China(2018AAA0101203)the National Natural Science Foundation of China(61673403,71601191)the JSPS KAKENHI(JP17K12751)。
文摘The multitrip pickup and delivery problem with time windows and manpower planning(MTPDPTW-MP)determines a set of ambulance routes and finds staff assignment for a hospital. It involves different stakeholders with diverse interests and objectives. This study firstly introduces a multiobjective MTPDPTW-MP(MO-MTPDPTWMP) with three objectives to better describe the real-world scenario. A multiobjective iterated local search algorithm with adaptive neighborhood selection(MOILS-ANS) is proposed to solve the problem. MOILS-ANS can generate a diverse set of alternative solutions for decision makers to meet their requirements. To better explore the search space, problem-specific neighborhood structures and an adaptive neighborhood selection strategy are carefully designed in MOILS-ANS. Experimental results show that the proposed MOILS-ANS significantly outperforms the other two multiobjective algorithms. Besides, the nature of objective functions and the properties of the problem are analyzed. Finally, the proposed MOILS-ANS is compared with the previous single-objective algorithm and the benefits of multiobjective optimization are discussed.
基金the financial support from National Natural Science Foundation of China(No.U1460101).
文摘Thermal spray coatings have been widely used on hearth rolls in a continuous annealing line to improve steel sheet quality and prolong the roll service life. One of the common defects formed on a working hearth roll is the oxide pickup. The most common cause of the pickup formation is that the active Mn oxide reacts with coating. The potentials of two different coatings, CoCrAlYTa-Al2O3 (No. 1) and CoCrYNi-Y2O3 (No. 2), to duplicate pickups by reacting with Fe and Mn oxides were studied. There are three stages during pickup producing and growing. No. 2 coating effectively reduced the corrosion of Mn oxide. The characterization and modification of the surface oxide formed can be changed with different dew points. The results indicate that the dew point from — 53 to — 10 ℃ can change the depth of Mn oxide, such that an alteration can prevent the first stage and second stage and is good for preventing the pickup growing.
基金The National Social Science Foundation of China(No.16CGL018)
文摘To occupy a greater market share in terminal distribution, companies are urged to make full use of cooperative coverage formed with brand effect and information sharing in the layout of pickup points. Based on the diversity of pickup points, the piecewise function, signal intensity function and probability function are introduced. Meanwhile, considering the effect of distance satisfaction and cooperation coverage on customer behavior, the location model of the pickup point under competitive environments is established. The genetic algorithm is used to solve the problem, and the effectiveness of the model and algorithm is verified by a case. The results show that the sensitivity of weighted demand coverages to budget decreases gradually. The maximum weighted demand coverage increases at first and then decreases with the increase of the signal threshold, and there is a positive correlation with the change of the actual demand coverage to the senior customers, but it is negatively related to the intermediate and primary customers. When the number of high-level pickup points in a competitive enterprise is small, the advantage of the target enterprise is more significant. Through comparison, the cooperative coverage model is better than the non-cooperative coverage model, in terms of the weighted demand coverage, the construction cost and the attention paid to the important customers.
基金supported by the National Key R&D Program of China(No.2022YFA1602201)。
文摘Accurate measurement of the transverse position of a beam is crucial in particle accelerators because it plays a key role in determining the beam parameters.Existing methods for beam-position measurement rely on the detection of image currents induced on electrodes or narrow-band wake field induced by a beam passing through a cavity-type structure.However,these methods have limitations.The indirect measurement of multiple parameters is computationally complex,requiring external calibration to determine the system parameters in advance.Furthermore,the utilization of the beam signal information is incomplete.Hence,this study proposes a novel method for measuring the absolute electron beam transverse position.By utilizing the geometric relationship between the center position of the measured electron beam and multiple detection electrodes and by analyzing the differences in the arrival times of the beam signals detected by these electrodes,the absolute transverse position of the electron beam crossing the electrode plane can be calculated.This method features absolute position measurement,a position sensitivity coefficient independent of vacuum chamber apertures,and no requirement for a symmetrical detector electrode layout.The feasibility of this method is validated through numerical simulations and beam experiments.
基金supported by the National Natural Science Foundation of China(Nos.11075100 and 11565001)。
文摘The nuclear charge pickup cross sections of 84Kr on CH2,C,and Al targets are investigated using CR-39 nuclear track detector at the highest energy of 395 MeV/u.The cross sections for H are calculated from those measured on C and CH2 targets.The dependence of the charge pickup cross section on target mass is studied.
基金National Natural Science Foundation of China(No.51375202)
文摘In order to improve the dust absorption performance of the reverse blowing pickup mouth, the gas-solid flow motion properties inside the reverse blowing pickup mouth were simulated by using computational fluid dynamics( CFD) software,Fluent.The results show that both the front baffle inclination angle and the pressure drop across the pickup mouth have significant impacts on dust absorption performance. As the inclination angle is increased,there is an increase in the overall and grade removal efficiency. As the front baffle inclination angle or pressure drop is increased,there is an increase in the overall and grade removal efficiencies.However,pressure drop affects energy consumption. Front baffle inclination angle and pressure drop are optimized. Optimal inclination angle and pressure drop are 105° and 2 300 Pa respectively. Sample machine is made and measured,which further verifies the appropriateness of numerical simulation and practicability of optimum strategy.
基金supported by the National Natural Science Foundation of China(Grants Nos 40725013 and 40674093)Chinese Academy of Sciences(Grant No KJCX2-YW-N28 9140C08060507ZCZJ19)
文摘Ion pickup by a monochromatic low-frequency Alfv6n wave, which propagates along the background magnetic field, has recently been investigated in a low beta plasma （Lu and Li 2007 Phys. Plasmas 14 042303）. In this paper, the monochromatic Alfven wave is generalized to a spectrum of Alfven waves with random phase. It finds that the process of ion pickup can be divided into two stages. First, ions are picked up in the transverse direction, and then phase difference （randomization） between ions due to their different parallel thermal motions leads to heating of the ions. The heating is dominant in the direction perpendicular to the background magnetic field. The temperatures of the ions at the asymptotic stage do not depend on individual waves in the spectrum, but are determined by the total amplitude of the waves. The effect of the initial ion bulk flow in the parallel direction on the heating is also considered in this paper.
基金Project Sponsored by Natural Science Foundation of Shanghai(97XD14005)
文摘This paper explained the mechanism of carbon pickup by ultra low carbon steels during continuous casting and indicated that the major cause of carbon pickup is the contact of the molten steel with the enriched carbon layer of the powder. Forming of the enriched carbon layer is due to the existing of “carbon core”. Accordingly, the measures to reduce the carbon content and amount of the enriched carbon layer were investigated. A kind of new powder has been developed and successfully used to minimize the carbon pickup by ultra low carbon steels during continuous casting.
