An operating schedule of the parallel electric arc furnaces(EAFs)considering both productivity and energy related criteria is investigated.A mathematical model is established to minimize the total completion time and ...An operating schedule of the parallel electric arc furnaces(EAFs)considering both productivity and energy related criteria is investigated.A mathematical model is established to minimize the total completion time and the total electricity cost.This problem is proved to be an NP-hard problem,and an effective solution algorithm,longest processing time-genetic(LPT-gene)algorithm,is proposed.The impacts of varied processing energy consumption and electricity price on the optimal schedules are analyzed.The integrated influence of the different weight values and the variation between the peak price and the trough price on the optimal solution is studied.Computational experiments illustrate that considering the energy consumption costs in production has little influence on makespan;the computational performance of the proposed longest processing time-genetic algorithm is better than the genetic algorithm(GA)in the issue to be studied;considerable reductions in the energy consumption costs can be achieved by avoiding producing during high-energy price periods and reducing the machining energy consumption difference.The results can be a guidance for managers to improve productivity and to save energy costs under the time-of-use tariffs.展开更多
One of the problems in using grating sensors is how to measure a small Bragg wavelength shift accurately. Nowadays demodulation techniques are mainly based on the edge filter, tunable filter, or interferometric scanni...One of the problems in using grating sensors is how to measure a small Bragg wavelength shift accurately. Nowadays demodulation techniques are mainly based on the edge filter, tunable filter, or interferometric scanning methods. Interferometric demodulation is widely accepted as the technology which can provide the high sensitivity. An interrogation system using the interferometric scanning method is presented, in which an unbalanced fiber M-Z interferometer is used as the wavelength scanner for temperature measurement. A novel fiber Bragg grating sensor system based on M-Z interferometric demodulation technique is presented in this paper. The temperature sensitivity measured in the experiment is almost consistent with that obtained from the theoretic calculation.展开更多
The theory of magnetic circuit design, the constitutive equations of a magneto-theological fluid, and the load properties of belt conveyors were used to design a magneto-rheological soft starter test-bed. The magnetic...The theory of magnetic circuit design, the constitutive equations of a magneto-theological fluid, and the load properties of belt conveyors were used to design a magneto-rheological soft starter test-bed. The magnetic field distribution in the working gap was analyzed and the current-speed relationship was investigated. A mathematical model for the time response was deduced. The results show that a linear relationship between current and magnetic field is seen when the magnetic materials are not saturated and the magnetic field is uniform in the working section. The rotation speed of the driven shaft changes linearly with increasing time. The response is rapid and can be as short as milliseconds. This meets the starting requirements of belt conveyors.展开更多
An approach based on multi-scale ehirplet sparse signal decomposition is proposed to separate the malti-component polynomial phase signals, and estimate their instantaneous frequencies. In this paper, we have generate...An approach based on multi-scale ehirplet sparse signal decomposition is proposed to separate the malti-component polynomial phase signals, and estimate their instantaneous frequencies. In this paper, we have generated a family of multi-scale chirplet functions which provide good local correlations of chirps over shorter time interval. At every decomposition stage, we build the so-called family of chirplets and our idea is to use a structured algorithm which exploits information in the family to chain chirplets together adaptively as to form the polyncmial phase signal component whose correlation with the current residue signal is largest. Simultaueously, the polynomial instantaneous frequency is estimated by connecting the linear frequency of the chirplet functions adopted in the current separation. Simulation experiment demonstrated that this method can separate the camponents of the multi-component polynamial phase signals effectively even in the low signal-to-noise ratio condition, and estimate its instantaneous frequency accurately.展开更多
The Dst index,designed as a proxy of ring current intensity,is known to be also affected by other magnetospheric current systems,e.g.magnetopause current.The pressure-corrected Dst index is obtained by removing the ef...The Dst index,designed as a proxy of ring current intensity,is known to be also affected by other magnetospheric current systems,e.g.magnetopause current.The pressure-corrected Dst index is obtained by removing the effects of the solar wind dynamic pressure and the quiet time ring current.However,all previous studies treated the correction coefficient as an averaged parameter for storms of different intensity.In this paper,based on the Burton's equations and employing two independent methods,we will show a positive correlation between pressure-correction coefficient b and the intensity of the storms.We divided our storm database(872 storms in total) into three categories according to the intensity of storms.In order to improve the accuracy of calculating,we also used the higher-resolution SYM-H index data instead of Dst index to compute the corrected Dst index during different storms.Furthermore,we are able to provide corrected magnetic storm index with high-time resolution(-1 min).展开更多
A multi-lattice deterministic trajectory(MLDT) model is developed to simulate dense gas-particle flow in a vertical channel.The actual inter-particle collision and particle motion are treated by a Lagrangian model wit...A multi-lattice deterministic trajectory(MLDT) model is developed to simulate dense gas-particle flow in a vertical channel.The actual inter-particle collision and particle motion are treated by a Lagrangian model with three sets of lattices to reduce computational time.Cluster formation and motion near the wall are successfully predicted with mean particle volume fraction and velocity,showing quantitatively agreement with experimental results.The mechanism of particles concentrated near the wall is investigated by considering effects of gravity,particle-wall collisions,inter-particle collisions and velocity profiles of the gas phase.It is shown that the inter-particle collision and gas-phase velocity distribution are the essential factors for cluster formation near the wall,while gravity and particle-wall collision only have minor effects on particle concentration near the wall.Particles are unable to remain in the high velocity region due to the strong inter-particle collisions,while they tend to stay in the low velocity region for weak inter-particle collisions.In addition,the effects of channel width and particle sizes on cluster formation are also investigated and it is found that particle concentration near the wall reduces with the decrease of channel width and increase of particle size.展开更多
基金The National Natural Science Foundation of China(No.71271054,71571042,71501046)the Fundamental Research Funds for the Central Universities(No.2242015S32023)the Scientific Research Innovation Project for College Graduates in Jiangsu Province(No.CXZZ12_0133)
文摘An operating schedule of the parallel electric arc furnaces(EAFs)considering both productivity and energy related criteria is investigated.A mathematical model is established to minimize the total completion time and the total electricity cost.This problem is proved to be an NP-hard problem,and an effective solution algorithm,longest processing time-genetic(LPT-gene)algorithm,is proposed.The impacts of varied processing energy consumption and electricity price on the optimal schedules are analyzed.The integrated influence of the different weight values and the variation between the peak price and the trough price on the optimal solution is studied.Computational experiments illustrate that considering the energy consumption costs in production has little influence on makespan;the computational performance of the proposed longest processing time-genetic algorithm is better than the genetic algorithm(GA)in the issue to be studied;considerable reductions in the energy consumption costs can be achieved by avoiding producing during high-energy price periods and reducing the machining energy consumption difference.The results can be a guidance for managers to improve productivity and to save energy costs under the time-of-use tariffs.
文摘One of the problems in using grating sensors is how to measure a small Bragg wavelength shift accurately. Nowadays demodulation techniques are mainly based on the edge filter, tunable filter, or interferometric scanning methods. Interferometric demodulation is widely accepted as the technology which can provide the high sensitivity. An interrogation system using the interferometric scanning method is presented, in which an unbalanced fiber M-Z interferometer is used as the wavelength scanner for temperature measurement. A novel fiber Bragg grating sensor system based on M-Z interferometric demodulation technique is presented in this paper. The temperature sensitivity measured in the experiment is almost consistent with that obtained from the theoretic calculation.
基金supported by the National Natural Science Foundation of China (Nos. 50975275 and 51075386)
文摘The theory of magnetic circuit design, the constitutive equations of a magneto-theological fluid, and the load properties of belt conveyors were used to design a magneto-rheological soft starter test-bed. The magnetic field distribution in the working gap was analyzed and the current-speed relationship was investigated. A mathematical model for the time response was deduced. The results show that a linear relationship between current and magnetic field is seen when the magnetic materials are not saturated and the magnetic field is uniform in the working section. The rotation speed of the driven shaft changes linearly with increasing time. The response is rapid and can be as short as milliseconds. This meets the starting requirements of belt conveyors.
基金supported by the National Science Foundation of China(No.50875078)
文摘An approach based on multi-scale ehirplet sparse signal decomposition is proposed to separate the malti-component polynomial phase signals, and estimate their instantaneous frequencies. In this paper, we have generated a family of multi-scale chirplet functions which provide good local correlations of chirps over shorter time interval. At every decomposition stage, we build the so-called family of chirplets and our idea is to use a structured algorithm which exploits information in the family to chain chirplets together adaptively as to form the polyncmial phase signal component whose correlation with the current residue signal is largest. Simultaueously, the polynomial instantaneous frequency is estimated by connecting the linear frequency of the chirplet functions adopted in the current separation. Simulation experiment demonstrated that this method can separate the camponents of the multi-component polynamial phase signals effectively even in the low signal-to-noise ratio condition, and estimate its instantaneous frequency accurately.
基金supported by the Key Project of the National Natural Science Foundation of China (Grant No 40831061)
文摘The Dst index,designed as a proxy of ring current intensity,is known to be also affected by other magnetospheric current systems,e.g.magnetopause current.The pressure-corrected Dst index is obtained by removing the effects of the solar wind dynamic pressure and the quiet time ring current.However,all previous studies treated the correction coefficient as an averaged parameter for storms of different intensity.In this paper,based on the Burton's equations and employing two independent methods,we will show a positive correlation between pressure-correction coefficient b and the intensity of the storms.We divided our storm database(872 storms in total) into three categories according to the intensity of storms.In order to improve the accuracy of calculating,we also used the higher-resolution SYM-H index data instead of Dst index to compute the corrected Dst index during different storms.Furthermore,we are able to provide corrected magnetic storm index with high-time resolution(-1 min).
基金partially supported by the National Basic Research Program of China ("973" Project) (Grant No. 62980532)
文摘A multi-lattice deterministic trajectory(MLDT) model is developed to simulate dense gas-particle flow in a vertical channel.The actual inter-particle collision and particle motion are treated by a Lagrangian model with three sets of lattices to reduce computational time.Cluster formation and motion near the wall are successfully predicted with mean particle volume fraction and velocity,showing quantitatively agreement with experimental results.The mechanism of particles concentrated near the wall is investigated by considering effects of gravity,particle-wall collisions,inter-particle collisions and velocity profiles of the gas phase.It is shown that the inter-particle collision and gas-phase velocity distribution are the essential factors for cluster formation near the wall,while gravity and particle-wall collision only have minor effects on particle concentration near the wall.Particles are unable to remain in the high velocity region due to the strong inter-particle collisions,while they tend to stay in the low velocity region for weak inter-particle collisions.In addition,the effects of channel width and particle sizes on cluster formation are also investigated and it is found that particle concentration near the wall reduces with the decrease of channel width and increase of particle size.