JSHM: A dynamic flexible job-shop scheduling method with human-machine collaboration

Objective To explore the effect of dynamic job scheduling method on the easing emergency department crowding.Methods Totals of 80 nurses in the emergency department at 6 pm-1 am from January to June in 2010 were control group,which adopted traditional scheduling model,and 80 nurses in emergency department at 6 pm-1 am from January to June in 2011 were control group were experimental group,which adopted dynamic job scheduling method.Then,satisfactionof patients,doctors,nurses and the quality of care were observed in two groups and compared.Results Between the experimental group and control group,patients' satisfaction (97.2 vs 90.6),doctors' satisfaction (96.0 vs 82.0),nurse satisfaction (96.3 vs 85.0),quality of care (87.21 ±4.31vs 92.26 ± 3.24),and the difference was statistically significant( x2 =9.862,5.005,5.959,8.636 ; respectively ; P ＜ 0.05 or P＜0.01).Conclusions Dynamic job scheduling method implementing can improve the disposal efficiency of emergency room,infusion room and observing room,reduce labor intensity of nurses,improve patients and accompany people's satisfaction,and effectively easing crowding of emergency room. Key words: Emergency service,hospital; Crowding; Nursing job; Dynamic scheduling

In the light of the dynamic capacity-increase problem of the limited buffer in flexible flow shops, this paper proposes a buffer dynamic capacity-increase scheduling method based on the public buffer, establishing a mathematical programming model of flexible flow shops with the limited buffer. According to the time cost of workpiece transferred into and out of the public buffer, we design the scheduling rules to control workpiece's access to and from the public buffer. Through the buffer dynamic capacity-increase scheduling method based on local scheduling rules as the core, the production blockage caused by capacity limitation of limited buffer in flexible flow shops is solved. Through the instance data test, a simulation experiment is designed to compare the scheduling result of the dynamic capacity-increase scheduling method in flexible flow shops with that of scheduling method without applying the proposed method. It is verified that this scheduling method is effective for solving such scheduling problems in actual workshop production.

When the current method is used to schedule railway transportation, the scheduling takes a long time, and the difference between the obtained scheduling result and the expected one is large, and there is a problem of low scheduling efficiency and poor validity. A dynamic scheduling method based on pre-classification is proposed, which pre-classifies railway transportation resources, improves the utilization rate of railway transportation resources, and shortens the time required for scheduling. The execution time is taken as the optimization target, and the railway transportation dynamic scheduling model is constructed based on the pre-classification results. The genetic algorithm is used to solve the dynamic scheduling model of railway transportation, and the dynamic scheduling of railway transportation is realized. The experimental results show that the proposed method takes less time for railway transportation scheduling, and requires less time to perform tasks after scheduling. The proposed method has high scheduling efficiency and good effectiveness.

Semiconductor manufacturing is considered as one of the most complex manufacturing process. Due to its large-scale, uncertainty, reentrance and mixed processing, it needs true dynamic scheduling method urgently. On the analysis of the self-organizing activities of ant colony system, the pheromone based dynamic scheduling rule is presented. The rule is simulated and the result analysis is given by comparing with other heuristic scheduling methods, which show that this method can optimize multi objectives of the semiconductor fabrication line and has a good perspective.

Research on Design Method of Dynamic Shop Floor Scheduling System Based on Human-computer Interaction

Coarse-grained reconfigurable architectures (CGRAs) are increasingly employed as domain-specific accelerators due to their efficiency and flexibility. A CGRA typically relies on compilers to perform task scheduling. The longstanding problem of static scheduling is that it suffers from insufficient parallelism in handling irregularities due to over-serialization and workload imbalance, which leads to severe resource underutilization and performance loss. To counteract the limitations of static scheduling in CGRAs, it is essential to exploit dynamic parallelism automatically and manage hardware resources adaptively. However, existing dynamic scheduling mechanisms, e.g., work stealing, often reschedule aggressively for instant performance but sacrifice efficiency, which is unfavorable to CGRAs that emphasize efficiency and fewer reconfigurations. This article proposes an elastic task scheduling scheme that enables lightweight dynamic scheduling in CGRAs. Tasks are rescheduled at runtime according to the classic tagged-token dataflow paradigm to enable dynamic task-level parallelism. Meanwhile, tasks are dynamically resized according to run-time throughputs via duplication, combination, and substitution operators for balanced multitask execution. We implement the elastic task scheduling scheme on a well-known reconfigurable architecture - triggered instruction architecture (TIA). Evaluation on the MachSuite benchmarks shows that the proposed scheme is effective in improving performance and energy efficiency. The average speedup is 2× over the baseline. Also, our design attains a 57 percent improvement in the area-normalized performance and a 49 percent better energy efficiency. Compared with a state-of-the-art dynamic scheduling method, our scheme achieves 1.6× speedup and 1.6× energy efficiency than work-stealing mechanism on the same substrate.

Synchronous Data Flow (SDF) is a well-known model of computation that is widely used in the control engineering and digital signal processing domains. Existing scheduling methods are mainly static approaches that assume full knowledge of the environment, e.g. data arrival times. In a growing number of practical cases like internet multimedia applications there exists only partial knowledge of the environment, e.g. average data rates. Here, only dynamic scheduling can yield optimal results. In this paper, we propose a new dynamic scheduling method that minimizes the maximal response time of the system. It is a generalization of a deadline revision method to allow treatment of data-dependent tasks using EDF scheduling. The applicability and benefit of the new approach is shown using a real-world example.

Flexible Job Shop Scheduling (FJSS) problem has many real-world applications such as manufacturing and cloud computing, and thus is an important area of study. In real world, the environment is often dynamic, and unpredicted job orders can arrive in real time. Dynamic FJSS consists of challenges of both dynamic optimisation and the FJSS problem. In Dynamic FJSS, two kinds of decisions (so-called routing and sequencing decisions) are to be made in real time. Dispatching rules have been demonstrated to be effective for dynamic scheduling due to their low computational complexity and ability to make real-time decisions. However, it is time consuming and strenuous to design effective dispatching rules manually due to the complex interactions between job shop attributes. Genetic Programming Hyper-heuristic (GPHH) has shown success in automatically designing dispatching rules which are much better than the manually designed ones. Previous works only focused on standard job shop scheduling with only the sequencing decisions. For FJSS, the routing rule is set arbitrarily by intuition. In this paper, we explore the possibility of evolving both routing and sequencing rules together and propose a new GPHH algorithm with Cooperative Co-evolution. Our results show that co-evolving the two rules together can lead to much more promising results than evolving the sequencing rule only.

<p><b>Dynamic flexible job shop scheduling (DFJSS) has received widespread attention from academia and industry due to its reflection in real-world scheduling applications such as order picking in the warehouse and the manufacturing industry. It requires complex routing and sequencing decisions under unpredicted dynamic events. Genetic programming, as ahyper-heuristic approach (GPHH), has been successfully applied to evolve scheduling heuristics for DFJSS automatically due to its flexible representation. Although GPHH has achieved certain success in solving the DFJSS problems, there are still some limitations for applying GPHH to DFJSS, particularly in terms of its training efficiency, large search space, search mechanism, and multitask solving ability. The overall goal of this thesis is to develop effective GPHH algorithmsto evolve scheduling heuristics for DFJSS efficiently. Different machine learning techniques, i.e., surrogate, feature selection, specialised genetic operator, and multitask learning, are incorporated in this thesis to tackle the limitations.</b></p> <p>First, this thesis develops a novel multi-fidelity based surrogate-assisted GPHH for DFJSS to improve the training efficiency of GPHH. Specifically, multi-fidelity based surrogate models are first designed by simplifying the problem to be solved. Then, an effective collaboration mechanism with knowledge transfer is proposed for utilising the advantages of the multifidelity based surrogate models to solve the problem. The results show that the proposed algorithm can dramatically reduce the computational cost of GPHH without sacrificing the performance in all the test scenarios. With the same training time, the proposed algorithm can achieve significantly better performance than its counterparts in most scenarios while no worse in others.</p> <p>Second, this thesis designs a novel two-stage GPHH framework with feature selection to evolve scheduling heuristics for DFJSS automatically. Based on this framework, this thesis further proposes to evolve scheduling heuristics with only the selected features by eliminating the unselected features properly. Specifically, individual adaptation strategies are proposed to generate individuals with only the selected features by utilising the information of both the selected features and the investigated individuals during the feature selection process. The results show that the proposed algorithm can successfully achieve scheduling heuristics with fewer unique features and smaller sizes, which tends to be more interpretable. In addition, the proposed algorithm can evolve comparable scheduling heuristic with that obtained by the traditional GPHH within a much shorter training time.</p> <p>Third, this thesis proposes a novel recombinative mechanism to provide guidance for GPHH based on the importance of subtrees to realise effective and adaptive recombination for parents to produce offspring. Two measures are proposed to measure the importance of all the subtrees of an individual. The first one is based on the frequency of features, and the second is based on the correlation between the behaviour of subtrees and the whole tree (i.e., an individual). The importance information is utilised to decide the crossover points for the parents. The proposed recombinative guidance mechanism attempts to improve the quality of offspring by preserving the promising building-blocks of one parent and incorporating good building-blocks from the other. The results show that the proposed algorithm based on the correlation importance measure performs better than the proposed algorithm based on the feature frequency importance measure. In addition, the proposed algorithm based on the correlation importance measure between the behaviour of subtrees significantly also outperforms the state-of-the-art algorithms on most tested scenarios.</p> <p>Last, this thesis proposes a multitask GPHH approach and a surrogate-assisted multitask GPHH approach to solving multiple DFJSS tasks simultaneously. First, an effective hyper-heuristic multitask algorithm is proposed by adapting the traditional evolutionary multitask algorithms based on the characteristics of GPHH. Second, this thesis develops a novel surrogate-assisted multitask GPHH approach to solving multiple DFJSS tasks by sharing useful knowledge between different DFJSS scheduling tasks. Specifically, the surrogate-assisted multitask GPHH algorithm employs the phenotypic characterisation technique to measure the behaviours of scheduling rules to build a surrogate for each task accordingly. The built surrogates are not only used to improve the efficiency of solving each single DFJSS task but also utilised for knowledge sharing between multiple DFJSS tasks in multitask learning. The results show that the proposed algorithm can significantly improve the quality of scheduling heuristics for all the test scenarios. The results also observe that the proposed algorithms manage to solve multiple tasks collaboratively in terms of the evolved scheduling heuristics for different tasks in a multitask scenario.</p>

Our experiments with Qlisp have led to two ways of improving the performance of parallel Lisp programs. One is to reduce the cost of process creation and scheduling; the other is to use a dynamic partitioning and scheduling method. We describe these techniques and present the results of several experiments that use them. We also present an analysis of the dynamic partitioning method to explain the reasons for its success.

© 2020, Springer Nature Switzerland AG. Dynamic flexible job shop scheduling (DFJSS) is a very valuable practical application problem that can be applied in many fields such as cloud computing and manufacturing. In DFJSS, machine assignment and operation sequencing decisions need to be made simultaneously in dynamic environments with unpredicted events such as new job arrivals. Scheduling heuristic is an ideal candidate for solving the DFJSS problem due to its efficiency and simplicity. Genetic programming (GP) has been successfully applied to evolve scheduling heuristics for job shop scheduling automatically. However, GP has a huge search space, and the traditional search algorithms do not utilise effectively the information obtained from the evolutionary process. This paper proposes a new method to make better use of the information during the evolutionary process of GP to further enhance the ability of GP. To be specific, this paper proposes two adaptive search strategies based on the frequency of features in promising individuals to guide GP to evolve effective rules. This paper examines the proposed algorithm on six different DFJSS scenarios. The results show that the proposed GP with adaptive search can converge faster and achieve significantly better performance than the GP without adaptive search in most scenarios while no worse in all other scenarios without increasing the computational cost.

This paper addresses the parameter modelling and optimisation issues in the application of a bio-inspired model for the scheduling of dynamic flexible job shop with sequence-dependent setups. The study sets the model parameters using two steps, termed mapping and tuning. Mapping establishes a set of coefficients to link the model parameters with the scheduling problem characteristics. Tuning determines good values of these coefficients and is then used to compute the model parameters. Such a tuning procedure is accomplished by extensive computational experiments and statistical analyses. A data set from semiconductor manufacturing was used to show the effectiveness of the parameter setting approach. The performance of the proposed multiagent model was compared with that of another scheduling method which is based on dispatching rules. It is concluded that the proposed parameter setting method is effective and worth considering when applying bio-inspired division of labour to dynamic manufacturing scheduling. [Received 5 October 2006; Revised 2 January 2007; Accepted 1 March 2007]

Genetic programming has been explored in recent works to evolve hyper-heuristics for dynamic flexible job shop scheduling. To generate optimum rules, the algorithm searches a space of trees composed from a set of terminals and operators. Since the search space is exponentially proportional to the size of the terminal set, it is preferred to opt out any insignificant terminals. Feature selection techniques has been employed to reduce the terminal set size without discarding any important information and they have proven to be effective for enhancing search performance and efficiency for dynamic flexible job shop scheduling. In this paper, we extends our previous work by adding a modified version of the two-stage genetic programming algorithm and by comparing the different methods in a larger experimental setup. The results show that feature selection can generate better rules in most of the cases while also being more efficient to in a production environment.KeywordsFeature selectionFlexible job shop schedulingDynamic schedulingGenetic programmingHyper heuristics

Multitasking learning has been successfully used in handling multiple related tasks simultaneously. In reality, there are often many tasks to be solved together, and the relatedness between them is unknown in advance. In this paper, we focus on multitask genetic programming for the dynamic flexible job shop scheduling problems, and address two challenges. The first is how to measure the relatedness between tasks accurately. The second is how to select task pairs to transfer knowledge during the multitask learning process. To measure the relatedness between dynamic flexible job shop scheduling tasks, we propose a new relatedness metric based on the behaviour distributions of the variable-length genetic programming individuals. In addition, for more effective knowledge transfer, we develop an adaptive strategy to choose the most suitable assisted task for the target task based on the relatedness information between tasks. The findings show that in all of the multitask scenarios studied, the proposed algorithm can substantially increase the effectiveness of the learned scheduling heuristics for all the desired tasks. The effectiveness of the proposed algorithm has also been verified by the analyses of task relatedness and structures of the evolved scheduling heuristics, and the discussions of population diversity and knowledge transfer.

This paper presents an optimization via simulation approach to solve dynamic flexible job shop scheduling problems. In most real-life problems, certain operation of a part can be processed on more than one machine, which makes the considered system (i.e., job shops) flexible. On one hand, flexibility provides alternative part routings which most of the time relaxes shop floor operations. On the other hand, increased flexibility makes operation machine pairing decisions (i.e., the most suitable part routing) much more complex. This study deals with both determining the best process plan for each part and then finding the best machine for each operation in a dynamic flexible job shop scheduling environment. In this respect, a genetic algorithm approach is adapted to determine best part processing plan for each part and then select appropriate machines for each operation of each part according to the determined part processing plan. Genetic algorithm solves the optimization phase of solution methodology. Then, these machine-operation pairings are utilized by discrete-event system simulation model to estimate their performances. These two phases of the study follow each other iteratively. The goal of methodology is to find the solution that minimizes total of average flowtimes for all parts. The results reveal that optimization via simulation approach is a good way to cope with dynamic flexible job shop scheduling problems, which usually takes NP-Hard form.