A discrete artificial bee colony algorithm is proposed for solving the blocking flow shop scheduling problem with total flow time criterion. Firstly, the solution in the algorithm is represented as job permutation. Se...A discrete artificial bee colony algorithm is proposed for solving the blocking flow shop scheduling problem with total flow time criterion. Firstly, the solution in the algorithm is represented as job permutation. Secondly, an initialization scheme based on a variant of the NEH (Nawaz-Enscore-Ham) heuristic and a local search is designed to construct the initial population with both quality and diversity. Thirdly, based on the idea of iterated greedy algorithm, some newly designed schemes for employed bee, onlooker bee and scout bee are presented. The performance of the proposed algorithm is tested on the well-known Taillard benchmark set, and the computational results demonstrate the effectiveness of the discrete artificial bee colony algorithm. In addition, the best known solutions of the benchmark set are provided for the blocking flow shop scheduling problem with total flow time criterion.展开更多
In many practical flowshop production environments, there is no intermediate storage space available to keep partially completed jobs between any two machines. The workflow has to be continuous, implying that the no-w...In many practical flowshop production environments, there is no intermediate storage space available to keep partially completed jobs between any two machines. The workflow has to be continuous, implying that the no-wait conditions must be abided, which is typical in steel and plastic production. We discuss the three-machine no-wait flowshop scheduling problem where the setup times are considered as separated from processing times and sequence independent. The scheduling goal is to minimize the total flowtime. An optimal property and two heuristic algorithms for this problem are proposed. Evaluated over a large number of problems, the proposed heuristics are found that they can yield good solutions effectively with low computational complexity, and have more obvious advantage for the large size problem compared with the existing one.展开更多
The flow shop scheduling problem with limited buffers( LBFSP) widely exists in manufacturing systems. A hybrid discrete harmony search algorithm is proposed for the problem to minimize total flow time. The algorithm p...The flow shop scheduling problem with limited buffers( LBFSP) widely exists in manufacturing systems. A hybrid discrete harmony search algorithm is proposed for the problem to minimize total flow time. The algorithm presents a novel discrete improvisation and a differential evolution scheme with the jobpermutation-based representation. Moreover,the discrete harmony search is hybridized with the problem-dependent local search based on insert neighborhood to balance the global exploration and local exploitation. In addition, an orthogonal experiment design is employed to provide a receipt for turning the adjustable parameters of the algorithm. Comparisons based on the Taillard benchmarks indicate the superiority of the proposed algorithm in terms of effectiveness and efficiency.展开更多
This paper reports that high-rate-deposition of microcrystalline silicon solar cells was performed by very-highfrequency plasma-enhanced chemical vapor deposition. These solar cells, whose intrinsic μc-Si：H layers w...This paper reports that high-rate-deposition of microcrystalline silicon solar cells was performed by very-highfrequency plasma-enhanced chemical vapor deposition. These solar cells, whose intrinsic μc-Si：H layers were prepared by using a different total gas flow rate （Ftotal）, behave much differently in performance, although their intrinsic layers have similar crystalline volume fraction, opto-electronic properties and a deposition rate of - 1.0 nm/s. The influence of Ftotal on the micro-structural properties was analyzed by Raman and Fourier transformed infrared measurements. The results showed that the vertical uniformity and the compact degree of μc-Si：H thin films were improved with increasing Ftotal. The variation of the microstructure was regarded as the main reason for the difference of the J V parameters. Combined with optical emission spectroscopy, we found that the gas temperature plays an important role in determining the microstructure of thin films. With Ftotal of 300 sccm, a conversion efficiency of 8.11% has been obtained for the intrinsic layer deposited at 8.5 A/s （1 A=0.1 nm）.展开更多
We present a study on n-type ternary InGaN layers grown by atmospheric pressure metalorganic vapour phase epitaxy （MOVPE） on GaN template/（0001） sapphire substrate. An investigation of the different growth conditi...We present a study on n-type ternary InGaN layers grown by atmospheric pressure metalorganic vapour phase epitaxy （MOVPE） on GaN template/（0001） sapphire substrate. An investigation of the different growth conditions on n-type InxGa1-xN （x = 0.06 -- 0.135） alloys was done for a series of five samples. The structural, electrical and optical properties were characterized by high resolution x-ray diffraction （HRXRD）, Hall effect and photolumineseence （PL）. Experimental results showed that different growth conditions, namely substrate rotation （SR） and change of total H2 flow （THF）, strongly affect the properties of InGaN layers. This case can be clearly observed from the analytical results. When the SR speed decreased, the HRXRD scan peak of the samples shifted along a higher angle. Therefore, increasing the SR speed changed important structural properties of InGaN alloys such as peak broadening, values of strain, lattice parameters and defects including tilt, twist and dislocation density. From PL results it is observed that the growth conditions can be changed to control the emission wavelength and it is possible to shift the emission wavelength towards the green. Hall effect measurement has shown that the resistivity of the samples changes dramatically when THF changes.展开更多
In this paper, the annular flow. model for in tube completed condensation is employed to predict the steady flow condensation heat transfer characteristics in a tube under zero-gravitation. In this easel it is propose...In this paper, the annular flow. model for in tube completed condensation is employed to predict the steady flow condensation heat transfer characteristics in a tube under zero-gravitation. In this easel it is proposed that vapor condenses on the liquid film surface. Due to the effect of surface tension, the liquid exists in the form of liquid film ring contacting wall; when the velocity of vapor core decreases to zerol the condensation process ends. Putting forward the physical and mathematical models, the problem is solved and the multi-order equation of the thickness of liquid film is obtained, which includes terms of the pressure gradient along axial direction, the friction force between vapor and liquid on interface. By computational calculation, this model can be used not only to predict the thickness of liquid film, the condensation pressure gradient along the axial direction, but also to determine the Nusselt number, the condensation length and the total flow pressure drop of condensation etc. At the end, the calculation results of the necessary condensation length are compared approximately with those from the experiments, which are obtained on the test set-up placed horizontally in gravitation field, and the deviation is analyzed.展开更多
This paper considers rearrangeable multihop lightwave networks whereby each network node is equipped with a number p of transmitters and receivers, and a spectrum of wavelengths is accessible by, and shared among, all...This paper considers rearrangeable multihop lightwave networks whereby each network node is equipped with a number p of transmitters and receivers, and a spectrum of wavelengths is accessible by, and shared among, all nodes by using the Wavelength Division Multiplexing (WDM). Depending on input traffic flow, nodal transmitters and receivers can be re-tuned to create virtual connectivity best suited with respect to a given optimization criterion. We present an efficient heuristic algorithm that combines two criteria for optimization: throughput maximization, as well as total flow minimization. Throughput maximization criterion is equivalent to congestion minimization, while minimizing total flow under the assumption of having links with equal lengths implies minimization of the average number of hops. Taking into account lengths of the links (i.e. link costs proportional with distances), the total flow minimization becomes equivalent to the total delay minimization. Tabu search is implemented as a two-phase strategy dealing with diversification as well as intensification of search. Computational experiments include consecutive runs with different sets of weights associated with the two criteria. Results for a benchmark set of problems are presented.展开更多
In recent years,scholars have made many research results on job-shop scheduling(JSP)problem,especially in single objective such as the maximum completion time.But most of the actual system scheduling problems are more...In recent years,scholars have made many research results on job-shop scheduling(JSP)problem,especially in single objective such as the maximum completion time.But most of the actual system scheduling problems are more than one object.Therefore,the research of multi-objective scheduling problem is very important and meaningful.In this paper,we proposed a multi-objective scheduling model which adopts weighted sum method to optimize two important indexes(makespan and total flow time).Genetic algorithm(GA)has diversified global search ability,while simulated annealing(SA)combined with tabu search(TS)have intensified capabilities in local neighborhood search.To overcome the drawback of the GA,we proposed a new hybrid GA(NewHGA)which produces initial solutions by GA firstly,and then take SA operator incorporate TS operator to search in the local space.By adding the novel local search strategy,the diversity of solutions will be improved greatly so that it can ensure the algorithm jump out of the local optimal value.We test this algorithm using the benchmark instances of different sizes taken from the OR-Library,and the results show that the algorithm is efficient than another hybrid algorithm.展开更多
基金Supported by the National Natural Science Foundation of China (61174040, 61104178)the Fundamental Research Funds for the Central Universities
文摘A discrete artificial bee colony algorithm is proposed for solving the blocking flow shop scheduling problem with total flow time criterion. Firstly, the solution in the algorithm is represented as job permutation. Secondly, an initialization scheme based on a variant of the NEH (Nawaz-Enscore-Ham) heuristic and a local search is designed to construct the initial population with both quality and diversity. Thirdly, based on the idea of iterated greedy algorithm, some newly designed schemes for employed bee, onlooker bee and scout bee are presented. The performance of the proposed algorithm is tested on the well-known Taillard benchmark set, and the computational results demonstrate the effectiveness of the discrete artificial bee colony algorithm. In addition, the best known solutions of the benchmark set are provided for the blocking flow shop scheduling problem with total flow time criterion.
文摘In many practical flowshop production environments, there is no intermediate storage space available to keep partially completed jobs between any two machines. The workflow has to be continuous, implying that the no-wait conditions must be abided, which is typical in steel and plastic production. We discuss the three-machine no-wait flowshop scheduling problem where the setup times are considered as separated from processing times and sequence independent. The scheduling goal is to minimize the total flowtime. An optimal property and two heuristic algorithms for this problem are proposed. Evaluated over a large number of problems, the proposed heuristics are found that they can yield good solutions effectively with low computational complexity, and have more obvious advantage for the large size problem compared with the existing one.
基金National Natural Science Foundations of China(Nos.61174040,61104178)Shanghai Commission of Science and Technology,China(No.12JC1403400)the Fundamental Research Funds for the Central Universities,China
文摘The flow shop scheduling problem with limited buffers( LBFSP) widely exists in manufacturing systems. A hybrid discrete harmony search algorithm is proposed for the problem to minimize total flow time. The algorithm presents a novel discrete improvisation and a differential evolution scheme with the jobpermutation-based representation. Moreover,the discrete harmony search is hybridized with the problem-dependent local search based on insert neighborhood to balance the global exploration and local exploitation. In addition, an orthogonal experiment design is employed to provide a receipt for turning the adjustable parameters of the algorithm. Comparisons based on the Taillard benchmarks indicate the superiority of the proposed algorithm in terms of effectiveness and efficiency.
基金supported by the National Basic Research Program of China (Grant Nos 2006CB202602 and 2006CB202603)the Tianjin Assistant Foundation for the National Basic Research Program of China (Grant No 07QTPTJC29500)the Natural Science Foundation of Tianjin (Grant No 07JCYBJC04000)
文摘This paper reports that high-rate-deposition of microcrystalline silicon solar cells was performed by very-highfrequency plasma-enhanced chemical vapor deposition. These solar cells, whose intrinsic μc-Si：H layers were prepared by using a different total gas flow rate （Ftotal）, behave much differently in performance, although their intrinsic layers have similar crystalline volume fraction, opto-electronic properties and a deposition rate of - 1.0 nm/s. The influence of Ftotal on the micro-structural properties was analyzed by Raman and Fourier transformed infrared measurements. The results showed that the vertical uniformity and the compact degree of μc-Si：H thin films were improved with increasing Ftotal. The variation of the microstructure was regarded as the main reason for the difference of the J V parameters. Combined with optical emission spectroscopy, we found that the gas temperature plays an important role in determining the microstructure of thin films. With Ftotal of 300 sccm, a conversion efficiency of 8.11% has been obtained for the intrinsic layer deposited at 8.5 A/s （1 A=0.1 nm）.
基金supported by the State Planning Organization of Turkey (Grant No 2001K120590)
文摘We present a study on n-type ternary InGaN layers grown by atmospheric pressure metalorganic vapour phase epitaxy （MOVPE） on GaN template/（0001） sapphire substrate. An investigation of the different growth conditions on n-type InxGa1-xN （x = 0.06 -- 0.135） alloys was done for a series of five samples. The structural, electrical and optical properties were characterized by high resolution x-ray diffraction （HRXRD）, Hall effect and photolumineseence （PL）. Experimental results showed that different growth conditions, namely substrate rotation （SR） and change of total H2 flow （THF）, strongly affect the properties of InGaN layers. This case can be clearly observed from the analytical results. When the SR speed decreased, the HRXRD scan peak of the samples shifted along a higher angle. Therefore, increasing the SR speed changed important structural properties of InGaN alloys such as peak broadening, values of strain, lattice parameters and defects including tilt, twist and dislocation density. From PL results it is observed that the growth conditions can be changed to control the emission wavelength and it is possible to shift the emission wavelength towards the green. Hall effect measurement has shown that the resistivity of the samples changes dramatically when THF changes.
文摘In this paper, the annular flow. model for in tube completed condensation is employed to predict the steady flow condensation heat transfer characteristics in a tube under zero-gravitation. In this easel it is proposed that vapor condenses on the liquid film surface. Due to the effect of surface tension, the liquid exists in the form of liquid film ring contacting wall; when the velocity of vapor core decreases to zerol the condensation process ends. Putting forward the physical and mathematical models, the problem is solved and the multi-order equation of the thickness of liquid film is obtained, which includes terms of the pressure gradient along axial direction, the friction force between vapor and liquid on interface. By computational calculation, this model can be used not only to predict the thickness of liquid film, the condensation pressure gradient along the axial direction, but also to determine the Nusselt number, the condensation length and the total flow pressure drop of condensation etc. At the end, the calculation results of the necessary condensation length are compared approximately with those from the experiments, which are obtained on the test set-up placed horizontally in gravitation field, and the deviation is analyzed.
基金This work was supported partly by the National Science Foundation Grant ANI 9814014 the project 036033-Architectural Elements for Regional Information Infrastructure, funded jointly by the Ministry of Science, Education and Sports of the Republic of Cr
文摘This paper considers rearrangeable multihop lightwave networks whereby each network node is equipped with a number p of transmitters and receivers, and a spectrum of wavelengths is accessible by, and shared among, all nodes by using the Wavelength Division Multiplexing (WDM). Depending on input traffic flow, nodal transmitters and receivers can be re-tuned to create virtual connectivity best suited with respect to a given optimization criterion. We present an efficient heuristic algorithm that combines two criteria for optimization: throughput maximization, as well as total flow minimization. Throughput maximization criterion is equivalent to congestion minimization, while minimizing total flow under the assumption of having links with equal lengths implies minimization of the average number of hops. Taking into account lengths of the links (i.e. link costs proportional with distances), the total flow minimization becomes equivalent to the total delay minimization. Tabu search is implemented as a two-phase strategy dealing with diversification as well as intensification of search. Computational experiments include consecutive runs with different sets of weights associated with the two criteria. Results for a benchmark set of problems are presented.
基金support of the National Science and Technology Supporting Plan of China(No.2013BAF02B09)for the work done in this paper.
文摘In recent years,scholars have made many research results on job-shop scheduling(JSP)problem,especially in single objective such as the maximum completion time.But most of the actual system scheduling problems are more than one object.Therefore,the research of multi-objective scheduling problem is very important and meaningful.In this paper,we proposed a multi-objective scheduling model which adopts weighted sum method to optimize two important indexes(makespan and total flow time).Genetic algorithm(GA)has diversified global search ability,while simulated annealing(SA)combined with tabu search(TS)have intensified capabilities in local neighborhood search.To overcome the drawback of the GA,we proposed a new hybrid GA(NewHGA)which produces initial solutions by GA firstly,and then take SA operator incorporate TS operator to search in the local space.By adding the novel local search strategy,the diversity of solutions will be improved greatly so that it can ensure the algorithm jump out of the local optimal value.We test this algorithm using the benchmark instances of different sizes taken from the OR-Library,and the results show that the algorithm is efficient than another hybrid algorithm.
