Li_(1.5)Ga_(0.5)Ti_(1.5)PO_(4))_(3)(LGTP)is recognized as a promising solid electrolyte material for lithium ions.In this work,LGTP solid electrolyte materials were prepared under different process conditions to explo...Li_(1.5)Ga_(0.5)Ti_(1.5)PO_(4))_(3)(LGTP)is recognized as a promising solid electrolyte material for lithium ions.In this work,LGTP solid electrolyte materials were prepared under different process conditions to explore the effects of sintering temperature and holding time on relative density,phase composition,microstructure,bulk conductivity,and total conductivity.In the impedance test under frequency of 1-10^(6) Hz,the bulk conductivity of the samples increased with increasing sintering temperature,and the total conductivity first increased and then decreased.SEM results showed that the average grain size in the ceramics was controlled by the sintering temperature,which increased from(0.54±0.01)μm to(1.21±0.01)μm when the temperature changed from 750 to 950°C.The relative density of the ceramics increased and then decreased with increasing temperature as the porosity increased.The holding time had little effect on the grain size growth or sample density,but an extended holding time resulted in crack generation that served to reduce the conductivity of the solid electrolyte.展开更多
Hydroxyapatite(HA)is a bio ceramic commonly utilized in bone tissue engineering due to its bioactive and osteoconductive properties.Crab shells are usually disregarded as waste material despite their significant CaCO_...Hydroxyapatite(HA)is a bio ceramic commonly utilized in bone tissue engineering due to its bioactive and osteoconductive properties.Crab shells are usually disregarded as waste material despite their significant CaCO_(3) content,and have not been widely utilized in the synthesis of HA.This study aims to synthesize and analyze HA derived from crab shells using the hydrothermal method with different durations of holding time.This study utilized precipitated calcium carbonate(PCC)derived from crab shells.With a hydrothermal reactor set at 160℃ and varying holding times of 14(HA_14),16(HA_16),and 18(HA_18)h,a PCC and(NH4)2HPO4 mixture was used to synthesize HA.The synthesis results were analyzed using scanning electron microscopy(SEM),fourier transform infrared spectroscopy(FTIR),and X-ray diffraction(XRD)tests.This study has accomplished the synthesis of HA from crab shells.Nonetheless,the final product of synthesis still contained CaCO_(3) as an impurity.The prolonged hydrothermal holding time of 14 to 18 h resulted in a reduction of impurities while increasing the percentage of crystal weight and crystallite size of HA.Specimen CH_18 is the best-quality product generated in this study.This specimen produced HA with the highest percentage of crystal weight and crystallite size compared to the other specimens.Furthermore,specimen CH_18 exhibited the lowest concentration of impurities.The Ca/P ratio in this specimen was also the closest to 1.67.The Ca/P ratio,crystallite size,and crystal weight percentage of this specimen are 1.54,19.06 nm,and 99.1%,respectively.展开更多
This study investigates the application of the two-parameter Weibull distribution in modeling state holding times within HIV/AIDS progression dynamics. By comparing the performance of the Weibull-based Accelerated Fai...This study investigates the application of the two-parameter Weibull distribution in modeling state holding times within HIV/AIDS progression dynamics. By comparing the performance of the Weibull-based Accelerated Failure Time (AFT) model, Cox Proportional Hazards model, and Survival model, we assess the effectiveness of these models in capturing survival rates across varying gender, age groups, and treatment categories. Simulated data was used to fit the models, with model identification criteria (AIC, BIC, and R2) applied for evaluation. Results indicate that the AFT model is particularly sensitive to interaction terms, showing significant effects for older age groups (50 - 60 years) and treatment interaction, while the Cox model provides a more stable fit across all age groups. The Survival model displayed variability, with its performance diminishing when interaction terms were introduced, particularly in older age groups. Overall, while the AFT model captures the complexities of interactions in the data, the Cox model’s stability suggests it may be better suited for general analyses without strong interaction effects. The findings highlight the importance of model selection in survival analysis, especially in complex disease progression scenarios like HIV/AIDS.展开更多
The two-stage hybridflow shop problem under setup times is addressed in this paper.This problem is NP-Hard.on the other hand,the studied problem is modeling different real-life applications especially in manufacturing...The two-stage hybridflow shop problem under setup times is addressed in this paper.This problem is NP-Hard.on the other hand,the studied problem is modeling different real-life applications especially in manufacturing and high performance-computing.Tackling this kind of problem requires the development of adapted algorithms.In this context,a metaheuristic using the genetic algorithm and three heuristics are proposed in this paper.These approximate solutions are using the optimal solution of the parallel machines under release and delivery times.Indeed,these solutions are iterative procedures focusing each time on a particular stage where a parallel machines problem is called to be solved.The general solution is then a concatenation of all the solutions in each stage.In addition,three lower bounds based on the relaxation method are provided.These lower bounds present a means to evaluate the efficiency of the developed algorithms throughout the measurement of the relative gap.An experimental result is discussed to evaluate the performance of the developed algorithms.In total,8960 instances are implemented and tested to show the results given by the proposed lower bounds and heuristics.Several indicators are given to compare between algorithms.The results illustrated in this paper show the performance of the developed algorithms in terms of gap and running time.展开更多
According to the Doehlert's matrix method, the adsorbent derived from sewage sludge was prepared through chemical activation under controlling the pyrolysis temperature and hold time. The characteristic parameters...According to the Doehlert's matrix method, the adsorbent derived from sewage sludge was prepared through chemical activation under controlling the pyrolysis temperature and hold time. The characteristic parameters including the total yield, adsorption of methylene blue, adsorption of iodine, BET surface area, micro-pore volume are 35%—49%, 16.5—38 mg/g, 285—362 mg/g, 185—359 m2/g, and 0.112—0.224 m3/g, respectively. According to the experimental data, the multi-linear regression method was adopted to fit the relations between the characteristic parameters and influential factors. At final, through optimization method, the optimal adsorbent is obtained when using 62 min as hold time and 1105K as pyrolysis temperature. Under the conditions, the adsorbent was produced and compared the characteristic parameters with model forecast value, the coherence is satisfied.展开更多
We aim in this research at synthesizing high-purity aluminium titanate with sludge from the aluminium profile factory by shock cooling method, and mainly discuss the effect of calcining reaction temperature and holdin...We aim in this research at synthesizing high-purity aluminium titanate with sludge from the aluminium profile factory by shock cooling method, and mainly discuss the effect of calcining reaction temperature and holding time on crystalline, microstructure and content of aluminum titanate materials to determine the preferred calcining temperature and holding time. XRD and SEM methods were utilized to characterize the crystalline and microstructure of each specimen, Rietveld Quantification software was used for the determination of different crystalline contents of specimens, and Philips plus software was applied to determine the cell parameters of aluminium titanate in different specimens. According to the experimental results, preferred calcining temperature is determined as 1400℃ and preferred holding time is 2 h, at which the grains of aluminum titanate grow completely and the purity of aluminum titanate is 97.2wt%.展开更多
Continuous annealing simulation tests were conducted by using a continuous annealing thermomechanical simulator. Holding times of 5, 60, 180, and 480 seconds for an intercritical annealing temperature of 820℃ were ad...Continuous annealing simulation tests were conducted by using a continuous annealing thermomechanical simulator. Holding times of 5, 60, 180, and 480 seconds for an intercritical annealing temperature of 820℃ were adopted to investigate the evolution of the mierostructure and mechanical properties of ferrite-bainite dual-phase steel. The ferrite-bainite dual-phase steel was characterized by high strength and low yield ratio due to the presence of the constituents (polygonal ferrite, bainite, martensite and retained austenite) of the steel microstructure. Specimen 3 exhibits the highest value of A50 (7.67%) and a product of Rm × A50 (10453MPa%) after a 180s holding. This is likely attributed to the presence of a C-enriched retained anstenite in the microstructure. And the effect of martensite islands and carbide precipitate is thought to be able to contribute in strengthening the present steel. It is expected that equilibrium of anstenite fraction would be reached for reasonable intercritical holding period, regardless of the heating temperature. The results suggest that long increasing holding times may not be needed because the major phase of the microstructure does not change very significantly. It is favorable for industrial production of DP steels to shorten holding times. Key words: ferrite-bainite dual-phase steel; holding time; martensite islands; mechanical properties展开更多
This paper studies a single machine scheduling problem with time-dependent learning and setup times. Time-dependent learning means that the actual processing time of a job is a function of the sum of the normal proces...This paper studies a single machine scheduling problem with time-dependent learning and setup times. Time-dependent learning means that the actual processing time of a job is a function of the sum of the normal processing times of the jobs already scheduled. The setup time of a job is proportional to the length of the already processed jobs, that is, past-sequence-dependent (psd) setup time. We show that the addressed problem remains polynomially solvable for the objectives, i.e., minimization of the total completion time and minimization of the total weighted completion time. We also show that the smallest processing time (SPT) rule provides the optimum sequence for the addressed problem.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 m-machine no-wait flowshop scheduling problem is addressed where setup times are treated as separate from processing times. The objective is to minimize total tardiness. Different dispatching rules have been inves...The m-machine no-wait flowshop scheduling problem is addressed where setup times are treated as separate from processing times. The objective is to minimize total tardiness. Different dispatching rules have been investigated and three were found to be superior. Two heuristics, a simulated annealing (SA) and a genetic algorithm (GA), have been proposed by using the best performing dispatching rule as the initial solution for SA, and the three superior dispatching rules as part of the initial population for GA. Moreover, improved versions of SA and GA are proposed using an insertion algorithm. Extensive computational experiments reveal that the improved versions of SA and GA perform about 95% better than SA and GA. The improved version of GA outperforms the improved version of SA by about 3.5%.展开更多
In the present paper, a total optimal cost of an inventory model with exponential declining demand and constant deterioration is considered. The time-varying holding cost is a linear function of time. Shortages are no...In the present paper, a total optimal cost of an inventory model with exponential declining demand and constant deterioration is considered. The time-varying holding cost is a linear function of time. Shortages are not allowed. The items (like food grains, fashion apparels and electronic equipments) have fixed shelf-life which decreases with time during the end of the season. A numerical example is presented to demonstrate the model and the sensitivity analysis of various parameters is carried out.展开更多
Motivated by industrial applications we study a single-machine scheduling problem in which all the jobs are mutu- ally independent and available at time zero.The machine processes the jobs sequentially and it is not i...Motivated by industrial applications we study a single-machine scheduling problem in which all the jobs are mutu- ally independent and available at time zero.The machine processes the jobs sequentially and it is not idle if there is any job to be pro- cessed.The operation of each job cannot be interrupted.The machine cannot process more than one job at a time.A setup time is needed if the machine switches from one type of job to another.The objective is to find an optimal schedule with the minimal total jobs’completion time.While the sum of jobs’processing time is always a constant,the objective is to minimize the sum of setup times.Ant colony optimization(ACO)is a meta-heuristic that has recently been applied to scheduling problem.In this paper we propose an improved ACO-Branching Ant Colony with Dynamic Perturbation(DPBAC)algorithm for the single-machine schedul- ing problem.DPBAC improves traditional ACO in following aspects:introducing Branching Method to choose starting points;im- proving state transition rules;introducing Mutation Method to shorten tours;improving pheromone updating rules and introduc- ing Conditional Dynamic Perturbation Strategy.Computational results show that DPBAC algorithm is superior to the traditional ACO algorithm.展开更多
Hypereutectic Al-40 wt.%Si alloys were fabricated by the combination of gas atomization and spark plasma sintering(SPS) technology. The effects of holding time(15-60 min) on phase composition, microstructure, density,...Hypereutectic Al-40 wt.%Si alloys were fabricated by the combination of gas atomization and spark plasma sintering(SPS) technology. The effects of holding time(15-60 min) on phase composition, microstructure, density,mechanical properties of Al-Si alloys were investigated by XRD, SEM, a hydrostatic balance, an automatic micro hardness tester and a universal tensile testing machine. The results showed that homogenous distribution of ultrafine primary Si and high density of alloys can be obtained at holding time of 30 min. Compared with primary Si(3.7 μm)fabricated by gas atomization, the average size increased from 5.17 to 7.72 μm with the increase of holding time during SPS process. Overall, the relative density, maximum tensile strength and Vickers hardness of 94.9%, 205 MPa and HV;196.86 were achieved at holding time of 30 min, respectively. In addition, all the diffraction peaks were corresponded to α-Al or β-Si and no other phase can be detected. Finally, the densification process of SPS was also discussed.展开更多
This work aims to give a systematic construction of the two families of mixed-integer-linear-programming (MILP) formulations, which are graph-<span style="font-family:;" "=""> </span&...This work aims to give a systematic construction of the two families of mixed-integer-linear-programming (MILP) formulations, which are graph-<span style="font-family:;" "=""> </span><span style="font-family:Verdana;">based and sequence-based, of the well-known scheduling problem<img src="Edit_41010f25-7ca5-482c-89be-790fad4616e1.png" alt="" /></span><span style="font-family:Verdana;text-align:justify;">. Two upper bounds of job completion times are introduced. A numerical test result analysis is conducted with a two-fold objective 1) testing the performance of each solving methods, and 2) identifying and analyzing the tractability of an instance according to the instance structure in terms of the number of machines, of the jobs setup time lengths and of the jobs release date distribution over the scheduling horizon.</span> <div> <span style="font-family:Verdana;text-align:justify;"><br /> </span> </div>展开更多
In this study, we consider the problem of scheduling a set of jobs with sequence-dependent setup times on a set of parallel production cells. The objective of this study is to minimize the total completion time. We no...In this study, we consider the problem of scheduling a set of jobs with sequence-dependent setup times on a set of parallel production cells. The objective of this study is to minimize the total completion time. We note that total customer demands for each type should be satisfied, and total required production time in each cell cannot exceed the capacity of the cell. This problem is formulated as an integer programming model and an interface is designed to provide integrity between data and software. Mathematical model is tested by both randomly generated data set and real-world data set from a factory that produce automotive components. As a result of this study, the solution which gives the best alternative production schedule is obtained.展开更多
采用1 mm Al+3 mm Mg+1 mm Al的组坯方式,轧制温度为400℃,压下率为35%,热轧得到6061/AZ31B/6061复合板。在退火温度为200℃的条件下,研究了不同退火时间对复合板拉伸性能、界面结合、微观组织以及表面残余应力的影响。在保温时间分别为...采用1 mm Al+3 mm Mg+1 mm Al的组坯方式,轧制温度为400℃,压下率为35%,热轧得到6061/AZ31B/6061复合板。在退火温度为200℃的条件下,研究了不同退火时间对复合板拉伸性能、界面结合、微观组织以及表面残余应力的影响。在保温时间分别为0、0.5、1和1.5 h情况下,分别进行拉伸实验、能谱分析、微观组织观察和残余应力测试。结果表明,当轧制压下率为35%时,6061铝合金和AZ31B镁合金能够通过热轧方法得到很好的复合;随着退火时间的增加,6061/AZ31B/6061复合板的拉伸强度、伸长率和界面扩散厚度显著增加,且铝合金表面残余应力也增大。展开更多
基金funded by the National Natural Science Foundation of China(Nos.51672310,51272288,51972344)。
文摘Li_(1.5)Ga_(0.5)Ti_(1.5)PO_(4))_(3)(LGTP)is recognized as a promising solid electrolyte material for lithium ions.In this work,LGTP solid electrolyte materials were prepared under different process conditions to explore the effects of sintering temperature and holding time on relative density,phase composition,microstructure,bulk conductivity,and total conductivity.In the impedance test under frequency of 1-10^(6) Hz,the bulk conductivity of the samples increased with increasing sintering temperature,and the total conductivity first increased and then decreased.SEM results showed that the average grain size in the ceramics was controlled by the sintering temperature,which increased from(0.54±0.01)μm to(1.21±0.01)μm when the temperature changed from 750 to 950°C.The relative density of the ceramics increased and then decreased with increasing temperature as the porosity increased.The holding time had little effect on the grain size growth or sample density,but an extended holding time resulted in crack generation that served to reduce the conductivity of the solid electrolyte.
基金funded the World Class Research(WCR)Grant of Universitas Diponegoro with Contract Number 357-36/UN7.D2/PP/IV/2024.
文摘Hydroxyapatite(HA)is a bio ceramic commonly utilized in bone tissue engineering due to its bioactive and osteoconductive properties.Crab shells are usually disregarded as waste material despite their significant CaCO_(3) content,and have not been widely utilized in the synthesis of HA.This study aims to synthesize and analyze HA derived from crab shells using the hydrothermal method with different durations of holding time.This study utilized precipitated calcium carbonate(PCC)derived from crab shells.With a hydrothermal reactor set at 160℃ and varying holding times of 14(HA_14),16(HA_16),and 18(HA_18)h,a PCC and(NH4)2HPO4 mixture was used to synthesize HA.The synthesis results were analyzed using scanning electron microscopy(SEM),fourier transform infrared spectroscopy(FTIR),and X-ray diffraction(XRD)tests.This study has accomplished the synthesis of HA from crab shells.Nonetheless,the final product of synthesis still contained CaCO_(3) as an impurity.The prolonged hydrothermal holding time of 14 to 18 h resulted in a reduction of impurities while increasing the percentage of crystal weight and crystallite size of HA.Specimen CH_18 is the best-quality product generated in this study.This specimen produced HA with the highest percentage of crystal weight and crystallite size compared to the other specimens.Furthermore,specimen CH_18 exhibited the lowest concentration of impurities.The Ca/P ratio in this specimen was also the closest to 1.67.The Ca/P ratio,crystallite size,and crystal weight percentage of this specimen are 1.54,19.06 nm,and 99.1%,respectively.
文摘This study investigates the application of the two-parameter Weibull distribution in modeling state holding times within HIV/AIDS progression dynamics. By comparing the performance of the Weibull-based Accelerated Failure Time (AFT) model, Cox Proportional Hazards model, and Survival model, we assess the effectiveness of these models in capturing survival rates across varying gender, age groups, and treatment categories. Simulated data was used to fit the models, with model identification criteria (AIC, BIC, and R2) applied for evaluation. Results indicate that the AFT model is particularly sensitive to interaction terms, showing significant effects for older age groups (50 - 60 years) and treatment interaction, while the Cox model provides a more stable fit across all age groups. The Survival model displayed variability, with its performance diminishing when interaction terms were introduced, particularly in older age groups. Overall, while the AFT model captures the complexities of interactions in the data, the Cox model’s stability suggests it may be better suited for general analyses without strong interaction effects. The findings highlight the importance of model selection in survival analysis, especially in complex disease progression scenarios like HIV/AIDS.
基金The authors would like to thank the Deanship of Scientific Research at Majmaah University for supporting this work under Project Number No.1439-19.
文摘The two-stage hybridflow shop problem under setup times is addressed in this paper.This problem is NP-Hard.on the other hand,the studied problem is modeling different real-life applications especially in manufacturing and high performance-computing.Tackling this kind of problem requires the development of adapted algorithms.In this context,a metaheuristic using the genetic algorithm and three heuristics are proposed in this paper.These approximate solutions are using the optimal solution of the parallel machines under release and delivery times.Indeed,these solutions are iterative procedures focusing each time on a particular stage where a parallel machines problem is called to be solved.The general solution is then a concatenation of all the solutions in each stage.In addition,three lower bounds based on the relaxation method are provided.These lower bounds present a means to evaluate the efficiency of the developed algorithms throughout the measurement of the relative gap.An experimental result is discussed to evaluate the performance of the developed algorithms.In total,8960 instances are implemented and tested to show the results given by the proposed lower bounds and heuristics.Several indicators are given to compare between algorithms.The results illustrated in this paper show the performance of the developed algorithms in terms of gap and running time.
文摘According to the Doehlert's matrix method, the adsorbent derived from sewage sludge was prepared through chemical activation under controlling the pyrolysis temperature and hold time. The characteristic parameters including the total yield, adsorption of methylene blue, adsorption of iodine, BET surface area, micro-pore volume are 35%—49%, 16.5—38 mg/g, 285—362 mg/g, 185—359 m2/g, and 0.112—0.224 m3/g, respectively. According to the experimental data, the multi-linear regression method was adopted to fit the relations between the characteristic parameters and influential factors. At final, through optimization method, the optimal adsorbent is obtained when using 62 min as hold time and 1105K as pyrolysis temperature. Under the conditions, the adsorbent was produced and compared the characteristic parameters with model forecast value, the coherence is satisfied.
基金supported by the Natural Science Foundation of Fujian Province (No. T08J0129)the Science and Technology Developing Foundation of Fuzhou University (No. 2008-XQ-001)2007-year New Century Talents Supporting Program of Fujian Province (No.XSJRC2007-17)
文摘We aim in this research at synthesizing high-purity aluminium titanate with sludge from the aluminium profile factory by shock cooling method, and mainly discuss the effect of calcining reaction temperature and holding time on crystalline, microstructure and content of aluminum titanate materials to determine the preferred calcining temperature and holding time. XRD and SEM methods were utilized to characterize the crystalline and microstructure of each specimen, Rietveld Quantification software was used for the determination of different crystalline contents of specimens, and Philips plus software was applied to determine the cell parameters of aluminium titanate in different specimens. According to the experimental results, preferred calcining temperature is determined as 1400℃ and preferred holding time is 2 h, at which the grains of aluminum titanate grow completely and the purity of aluminum titanate is 97.2wt%.
基金Founded by National Natural Science Foundation of China(No.51004037)Shenyang City Application Basic Research Project(No.F13-316-1-15)State Key Laboratory Opening Project of Northeastern University(No.12SYS05)
文摘Continuous annealing simulation tests were conducted by using a continuous annealing thermomechanical simulator. Holding times of 5, 60, 180, and 480 seconds for an intercritical annealing temperature of 820℃ were adopted to investigate the evolution of the mierostructure and mechanical properties of ferrite-bainite dual-phase steel. The ferrite-bainite dual-phase steel was characterized by high strength and low yield ratio due to the presence of the constituents (polygonal ferrite, bainite, martensite and retained austenite) of the steel microstructure. Specimen 3 exhibits the highest value of A50 (7.67%) and a product of Rm × A50 (10453MPa%) after a 180s holding. This is likely attributed to the presence of a C-enriched retained anstenite in the microstructure. And the effect of martensite islands and carbide precipitate is thought to be able to contribute in strengthening the present steel. It is expected that equilibrium of anstenite fraction would be reached for reasonable intercritical holding period, regardless of the heating temperature. The results suggest that long increasing holding times may not be needed because the major phase of the microstructure does not change very significantly. It is favorable for industrial production of DP steels to shorten holding times. Key words: ferrite-bainite dual-phase steel; holding time; martensite islands; mechanical properties
文摘This paper studies a single machine scheduling problem with time-dependent learning and setup times. Time-dependent learning means that the actual processing time of a job is a function of the sum of the normal processing times of the jobs already scheduled. The setup time of a job is proportional to the length of the already processed jobs, that is, past-sequence-dependent (psd) setup time. We show that the addressed problem remains polynomially solvable for the objectives, i.e., minimization of the total completion time and minimization of the total weighted completion time. We also show that the smallest processing time (SPT) rule provides the optimum sequence for the addressed problem.
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.
文摘The m-machine no-wait flowshop scheduling problem is addressed where setup times are treated as separate from processing times. The objective is to minimize total tardiness. Different dispatching rules have been investigated and three were found to be superior. Two heuristics, a simulated annealing (SA) and a genetic algorithm (GA), have been proposed by using the best performing dispatching rule as the initial solution for SA, and the three superior dispatching rules as part of the initial population for GA. Moreover, improved versions of SA and GA are proposed using an insertion algorithm. Extensive computational experiments reveal that the improved versions of SA and GA perform about 95% better than SA and GA. The improved version of GA outperforms the improved version of SA by about 3.5%.
文摘In the present paper, a total optimal cost of an inventory model with exponential declining demand and constant deterioration is considered. The time-varying holding cost is a linear function of time. Shortages are not allowed. The items (like food grains, fashion apparels and electronic equipments) have fixed shelf-life which decreases with time during the end of the season. A numerical example is presented to demonstrate the model and the sensitivity analysis of various parameters is carried out.
文摘Motivated by industrial applications we study a single-machine scheduling problem in which all the jobs are mutu- ally independent and available at time zero.The machine processes the jobs sequentially and it is not idle if there is any job to be pro- cessed.The operation of each job cannot be interrupted.The machine cannot process more than one job at a time.A setup time is needed if the machine switches from one type of job to another.The objective is to find an optimal schedule with the minimal total jobs’completion time.While the sum of jobs’processing time is always a constant,the objective is to minimize the sum of setup times.Ant colony optimization(ACO)is a meta-heuristic that has recently been applied to scheduling problem.In this paper we propose an improved ACO-Branching Ant Colony with Dynamic Perturbation(DPBAC)algorithm for the single-machine schedul- ing problem.DPBAC improves traditional ACO in following aspects:introducing Branching Method to choose starting points;im- proving state transition rules;introducing Mutation Method to shorten tours;improving pheromone updating rules and introduc- ing Conditional Dynamic Perturbation Strategy.Computational results show that DPBAC algorithm is superior to the traditional ACO algorithm.
基金Project(18JS060) supported by the Shaanxi Key Laboratory of Nano-materials and Technology,ChinaProject(2018JQ5087) supported by Natural Science Basic Research Plan of Shaanxi Province,China。
文摘Hypereutectic Al-40 wt.%Si alloys were fabricated by the combination of gas atomization and spark plasma sintering(SPS) technology. The effects of holding time(15-60 min) on phase composition, microstructure, density,mechanical properties of Al-Si alloys were investigated by XRD, SEM, a hydrostatic balance, an automatic micro hardness tester and a universal tensile testing machine. The results showed that homogenous distribution of ultrafine primary Si and high density of alloys can be obtained at holding time of 30 min. Compared with primary Si(3.7 μm)fabricated by gas atomization, the average size increased from 5.17 to 7.72 μm with the increase of holding time during SPS process. Overall, the relative density, maximum tensile strength and Vickers hardness of 94.9%, 205 MPa and HV;196.86 were achieved at holding time of 30 min, respectively. In addition, all the diffraction peaks were corresponded to α-Al or β-Si and no other phase can be detected. Finally, the densification process of SPS was also discussed.
文摘This work aims to give a systematic construction of the two families of mixed-integer-linear-programming (MILP) formulations, which are graph-<span style="font-family:;" "=""> </span><span style="font-family:Verdana;">based and sequence-based, of the well-known scheduling problem<img src="Edit_41010f25-7ca5-482c-89be-790fad4616e1.png" alt="" /></span><span style="font-family:Verdana;text-align:justify;">. Two upper bounds of job completion times are introduced. A numerical test result analysis is conducted with a two-fold objective 1) testing the performance of each solving methods, and 2) identifying and analyzing the tractability of an instance according to the instance structure in terms of the number of machines, of the jobs setup time lengths and of the jobs release date distribution over the scheduling horizon.</span> <div> <span style="font-family:Verdana;text-align:justify;"><br /> </span> </div>
文摘In this study, we consider the problem of scheduling a set of jobs with sequence-dependent setup times on a set of parallel production cells. The objective of this study is to minimize the total completion time. We note that total customer demands for each type should be satisfied, and total required production time in each cell cannot exceed the capacity of the cell. This problem is formulated as an integer programming model and an interface is designed to provide integrity between data and software. Mathematical model is tested by both randomly generated data set and real-world data set from a factory that produce automotive components. As a result of this study, the solution which gives the best alternative production schedule is obtained.
文摘采用1 mm Al+3 mm Mg+1 mm Al的组坯方式,轧制温度为400℃,压下率为35%,热轧得到6061/AZ31B/6061复合板。在退火温度为200℃的条件下,研究了不同退火时间对复合板拉伸性能、界面结合、微观组织以及表面残余应力的影响。在保温时间分别为0、0.5、1和1.5 h情况下,分别进行拉伸实验、能谱分析、微观组织观察和残余应力测试。结果表明,当轧制压下率为35%时,6061铝合金和AZ31B镁合金能够通过热轧方法得到很好的复合;随着退火时间的增加,6061/AZ31B/6061复合板的拉伸强度、伸长率和界面扩散厚度显著增加,且铝合金表面残余应力也增大。