The batch splitting scheduling problem has recently become a major target in manufacturing systems, and the researchers have obtained great achievements, whereas most of existing related researches focus on equal-size...The batch splitting scheduling problem has recently become a major target in manufacturing systems, and the researchers have obtained great achievements, whereas most of existing related researches focus on equal-sized and consistent-sized batch splitting scheduling problem, and solve the problem by fixing the number of sub-batches, or the sub-batch sizes, or both. Under such circumstance and to provide a practical method for production scheduling in batch production mode, a study was made on the batch splitting scheduling problem on alternative machines, based on the objective to minimize the makespan. A scheduling approach was presented to address the variable-sized batch splitting scheduling problem in job shops trying to optimize both the number of sub-bathes and the sub-batch sizes, based on differential evolution（DE）, making full use of the finding that the sum of values of genes in one chromosome remains the same before and after mutation in DE. Considering before-arrival set-up time and processing time separately, a variable-sized batch splitting scheduling model was established and a new hybrid algorithm was brought forward to solve both the batch splitting problem and the batch scheduling problem. A new parallel chromosome representation was adopted, and the batch scheduling chromosome and the batch splitting chromosome were treated separately during the global search procedure, based on self-adaptive DE and genetic crossover operator, respectively. A new local search method was further designed to gain a better performance. A solution consists of the optimum number of sub-bathes for each operation per job, the optimum batch size for each sub-batch and the optimum sequence of sub-batches. Computational experiments of four test instances and a realistic problem in a speaker workshop were performed to testify the effectiveness of the proposed scheduling method. The study takes advantage of DE＇s distinctive feature, and employs the algorithm as a solution approach, and thereby deepens and enriches the content of batch splitting scheduling.展开更多
Given a list of items and a sequence of variable-sized bins arriving one by one, it is NP-hard to pack the items into the bin list with a goal to minimize the total size of bins from the earliest one to the last used....Given a list of items and a sequence of variable-sized bins arriving one by one, it is NP-hard to pack the items into the bin list with a goal to minimize the total size of bins from the earliest one to the last used. In this paper a set of approximation algorithms is presented for cases in which the ability to preview at most k（〉=2） arriving bins is given. With the essential assumption that all bin sizes are not less than the largest item size, analytical results show the asymptotic worst case ratios of all k-bounded space and offiine algorithms are 2. Based on experiments by applying algorithms to instances in which item sizes and bin sizes are drawn independently from the continuous uniform distribution respectively in the interval [0,u] and [u,l ], averagecase experimental results show that, with fixed k, algorithms with the Best Fit packing（closing） rule are statistically better than those with the First Fit packing（closing） rule.展开更多
This paper suggests a chunk approach to solve the plateau problem among advanced English learners. The paper first discusses the extant problems and then provides a definition of the chunk approach. Based on some rese...This paper suggests a chunk approach to solve the plateau problem among advanced English learners. The paper first discusses the extant problems and then provides a definition of the chunk approach. Based on some research results in cognitive psychology, it analyses the important role that chunks play in language acquisition and production and thus provides a cognitive foundation for implementing the chunk approach in English teaching. The paper also offers a set of classroom activities which can be easily adopted or adapted by other teachers.展开更多
本研究从社会认知语用视角出发,制定语言创造性的判定步骤,考察维也纳-牛津国际英语语料库(Vienna-Oxford International Corpus of English,简称:VOICE)中视觉动词词块的创造性特征,揭示其意义建构模式和认知语用生成机制。研究发现,...本研究从社会认知语用视角出发,制定语言创造性的判定步骤,考察维也纳-牛津国际英语语料库(Vienna-Oxford International Corpus of English,简称:VOICE)中视觉动词词块的创造性特征,揭示其意义建构模式和认知语用生成机制。研究发现,在多元文化互动语境中,视觉动词词块的创造性趋势显著,尤其表现为蓄意创造性特征。其次,创造性词块的意义建构过程具有动态性、交互性和涌现性特征,具体表现为英语非本族语者善于调动潜在的多元文化资源,共建共知基础,共商、共享创造性词块的意义。最后,创造性词块的生成过程受特定情景语境、前经验、语用目的和认知努力等因素制约。这些发现对于深化语言创造性研究以及促进多元文化语用实践具有直接现实性意义。展开更多
基金supported by National Hi-tech Research and Development Program of China (863 Program, Grant No. 2007AA04Z155)National Natural Science Foundation of China (Grant No. 60970021)Zhejiang Provincial Natural Science Foundation of China (Grant No. Y1090592)
文摘The batch splitting scheduling problem has recently become a major target in manufacturing systems, and the researchers have obtained great achievements, whereas most of existing related researches focus on equal-sized and consistent-sized batch splitting scheduling problem, and solve the problem by fixing the number of sub-batches, or the sub-batch sizes, or both. Under such circumstance and to provide a practical method for production scheduling in batch production mode, a study was made on the batch splitting scheduling problem on alternative machines, based on the objective to minimize the makespan. A scheduling approach was presented to address the variable-sized batch splitting scheduling problem in job shops trying to optimize both the number of sub-bathes and the sub-batch sizes, based on differential evolution（DE）, making full use of the finding that the sum of values of genes in one chromosome remains the same before and after mutation in DE. Considering before-arrival set-up time and processing time separately, a variable-sized batch splitting scheduling model was established and a new hybrid algorithm was brought forward to solve both the batch splitting problem and the batch scheduling problem. A new parallel chromosome representation was adopted, and the batch scheduling chromosome and the batch splitting chromosome were treated separately during the global search procedure, based on self-adaptive DE and genetic crossover operator, respectively. A new local search method was further designed to gain a better performance. A solution consists of the optimum number of sub-bathes for each operation per job, the optimum batch size for each sub-batch and the optimum sequence of sub-batches. Computational experiments of four test instances and a realistic problem in a speaker workshop were performed to testify the effectiveness of the proposed scheduling method. The study takes advantage of DE＇s distinctive feature, and employs the algorithm as a solution approach, and thereby deepens and enriches the content of batch splitting scheduling.
文摘Given a list of items and a sequence of variable-sized bins arriving one by one, it is NP-hard to pack the items into the bin list with a goal to minimize the total size of bins from the earliest one to the last used. In this paper a set of approximation algorithms is presented for cases in which the ability to preview at most k（〉=2） arriving bins is given. With the essential assumption that all bin sizes are not less than the largest item size, analytical results show the asymptotic worst case ratios of all k-bounded space and offiine algorithms are 2. Based on experiments by applying algorithms to instances in which item sizes and bin sizes are drawn independently from the continuous uniform distribution respectively in the interval [0,u] and [u,l ], averagecase experimental results show that, with fixed k, algorithms with the Best Fit packing（closing） rule are statistically better than those with the First Fit packing（closing） rule.
文摘This paper suggests a chunk approach to solve the plateau problem among advanced English learners. The paper first discusses the extant problems and then provides a definition of the chunk approach. Based on some research results in cognitive psychology, it analyses the important role that chunks play in language acquisition and production and thus provides a cognitive foundation for implementing the chunk approach in English teaching. The paper also offers a set of classroom activities which can be easily adopted or adapted by other teachers.
文摘本研究从社会认知语用视角出发,制定语言创造性的判定步骤,考察维也纳-牛津国际英语语料库(Vienna-Oxford International Corpus of English,简称:VOICE)中视觉动词词块的创造性特征,揭示其意义建构模式和认知语用生成机制。研究发现,在多元文化互动语境中,视觉动词词块的创造性趋势显著,尤其表现为蓄意创造性特征。其次,创造性词块的意义建构过程具有动态性、交互性和涌现性特征,具体表现为英语非本族语者善于调动潜在的多元文化资源,共建共知基础,共商、共享创造性词块的意义。最后,创造性词块的生成过程受特定情景语境、前经验、语用目的和认知努力等因素制约。这些发现对于深化语言创造性研究以及促进多元文化语用实践具有直接现实性意义。
