| Records |
| Author |
Alvarez-Miranda, E.; Pereira, J.; Torrez-Meruvia H.; Vila, M. |
| Title |
A Hybrid Genetic Algorithm for the Simple Assembly Line Balancing Problem with a Fixed Number of Workstations |
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Year  |
2021 |
Publication |
Mathematics |
Abbreviated Journal |
Mathematics |
| Volume |
9 |
Issue |
17 |
Pages |
2157 |
| Keywords |
assembly lines; manufacturing; line balancing; hybrid genetic algorithm |
| Abstract |
The assembly line balancing problem is a classical optimisation problem whose objective is to assign each production task to one of the stations on the assembly line so that the total efficiency of the line is maximized. This study proposes a novel hybrid method to solve the simple version of the problem in which the number of stations is fixed, a problem known as SALBP-2. The hybrid differs from previous approaches by encoding individuals of a genetic algorithm as instances of a modified problem that contains only a subset of the solutions to the original formulation. These individuals are decoded to feasible solutions of the original problem during fitness evaluation in which the resolution of the modified problem is conducted using a dynamic programming based approach that uses new bounds to reduce its state space. Computational experiments show the efficiency of the method as it is able to obtain several new best-known solutions for some of the benchmark instances used in the literature for comparison purposes. |
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2227-7390 |
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WOS:000694360700001 |
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| Call Number |
UAI @ alexi.delcanto @ |
Serial |
1466 |
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| Author |
Pereira, J.; Ritt, M |
| Title |
A note on “Algorithms for the Calzedonia workload allocation problem” |
Type |
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| Year |
2022 |
Publication |
Journal of the Operational Research Society |
Abbreviated Journal |
J. Oper. Res. Soc. |
| Volume |
73 |
Issue |
6 |
Pages |
1420-1422 |
| Keywords |
Assembly line balancing; worker allocation; dynamic programming |
| Abstract |
Battarra et al. recently proposed a novel assembly line balancing problem with applications to the apparel industry, where the tasks are performed in a fixed order. To solve the problem, one has to assign workers and tasks to the workstations with the objective of maximising the throughput of the assembly line. In this paper, we provide dynamic programming formulations for the general problem and some special cases. We then use these formulations to develop an exact solution approach that optimally solves the instances in Battarra et al. within seconds. |
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0160-5682 |
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| Notes |
WOS:000627308200001 |
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UAI @ alexi.delcanto @ |
Serial |
1351 |
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| Author |
Alvarez-Miranda, E.; Pereira, J. |
| Title |
A Districting Application with a Quality of Service Objective |
Type |
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| Year |
2022 |
Publication |
Mathematics |
Abbreviated Journal |
Mathematics |
| Volume |
10 |
Issue |
1 |
Pages |
13 |
| Keywords |
districtin; glast-mile delivery; hybrid heuristics |
| Abstract |
E-commerce sales have led to a considerable increase in the demand for last-mile delivery companies, revealing several problems in their logistics processes. Among these problems, are not meeting delivery deadlines. For example, in Chile, the national consumer service (SERNAC) indicated that in 2018, late deliveries represented 23% of complaints in retail online sales and were the second most common reason for complaints. Some of the causes are incorrectly designed delivery zones because in many cases, these delivery zones do not account for the demographic growth of cities. The result is an imbalanced workload between different zones, which leads to some resources being idle while others fail to meet their workload in satisfactory conditions. The present work proposes a hybrid method for designing delivery zones with an objective based on improving the quality of express delivery services. The proposed method combines a preprocess based on the grouping of demand in areas according to the structure of the territory, a heuristic that generates multiple candidates for the distribution zones, and a mathematical model that combines the different distribution zones generated to obtain a final territorial design. To verify the applicability of the proposed method, a case study is considered based on the real situation of a Chilean courier company with low service fulfillment in its express deliveries. The results obtained from the computational experiments show the applicability of the method, highlighting the validity of the aggregation procedure and improvements in the results obtained using the hybrid method compared to the initial heuristic. The final solution improves the ability to meet the conditions associated with express deliveries, compared with the current situation, by 12 percentage points. The results also allow an indicative sample of the critical service factors of a company to be obtained, identifying the effects of possible changes in demand or service conditions. |
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2227-7390 |
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| Notes |
WOS:000751158600001 |
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UAI @ alexi.delcanto @ |
Serial |
1529 |
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| Author |
Yuraszeck, F.; Mejia, G.; Pereira, J.; Vila, M. |
| Title |
A Novel Constraint Programming Decomposition Approach for the Total Flow Time Fixed Group Shop Scheduling Problem |
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| Year |
2022 |
Publication |
Mathematics |
Abbreviated Journal |
Mathematics |
| Volume |
10 |
Issue |
3 |
Pages |
329 |
| Keywords |
scheduling; fixed group shop; group shop; constraint programming |
| Abstract |
This work addresses a particular case of the group shop scheduling problem (GSSP) which will be denoted as the fixed group shop scheduling problem (FGSSP). In a FGSSP, job operations are divided into stages and each stage has a set of machines associated to it which are not shared with the other stages. All jobs go through all the stages in a specific order, where the operations of the job at each stage need to be finished before the job advances to the following stage, but operations within a stage can be performed in any order. This setting is common in companies such as leaf spring manufacturers and other automotive companies. To solve the problem, we propose a novel heuristic procedure that combines a decomposition approach with a constraint programming (CP) solver and a restart mechanism both to avoid local optima and to diversify the search. The performance of our approach was tested on instances derived from other scheduling problems that the FGSSP subsumes, considering both the cases with and without anticipatory sequence-dependent setup times. The results of the proposed algorithm are compared with off-the-shelf CP and mixed integer linear programming (MILP) methods as well as with the lower bounds derived from the study of the problem. The experiments show that the proposed heuristic algorithm outperforms the other methods, specially on large-size instances with improvements of over 10% on average. |
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2227-7390 |
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| Notes |
WOS:000756126100001 |
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UAI @ alexi.delcanto @ |
Serial |
1549 |
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| Author |
Alvarez-Miranda, E.; Pereira, J.; Vargas, C.; Vila, M. |
| Title |
Variable-depth local search heuristic for assembly line balancing problems |
Type |
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| Year |
2022 |
Publication |
International Journal Of Production Research |
Abbreviated Journal |
Int. J. Prod. Res. |
| Volume |
61 |
Issue |
9 |
Pages |
3103-3121 |
| Keywords |
Assembly lines; Manufacturing; simple assembly line balancing; local search; variable-depth local search |
| Abstract |
Assembly lines are production flow systems wherein activities are organised around a line consisting of various workstations through which the product flows. At each station, the product is assembled through a subset of operations. The assembly line balancing problem (ALBP) consists of allocating operations between stations to maximise the system efficiency. In this study, a variable-depth local search algorithm is proposed for solving simple assembly line balancing problems (SALBPs), which are the most widely studied versions of the ALBP. Although the state-of-the-art techniques for solving the SALBP consist of exact enumeration-based methods or heuristics, this paper proposes a local search-based heuristic using variable-length sequences that allow the solution space to be efficiently explored. The proposed algorithm improves the best solution known for multiple instances reported in the literature, indicating that its efficiency is comparable to those of the state-of-the-art method for solving the SALBP. Moreover, the characteristics of the instances for which the proposed procedure provides a better solution than previously reported construction procedures are investigated. |
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0020-7543 |
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| Notes |
WOS:000800928700001 |
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UAI @ alexi.delcanto @ |
Serial |
1578 |
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| Author |
Sandoval, G.; Alvarez-Miranda, E.; Pereira, J.; Rios-Mercado, R.Z.; Diaz, J.A. |
| Title |
A novel districting design approach for on-time last-mile delivery: An application on an express postal company |
Type |
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| Year |
2022 |
Publication |
Omega-International Journal Of Management Science |
Abbreviated Journal |
Omega-Int. J. Manage. Sci. |
| Volume |
113 |
Issue |
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Pages |
102687 |
| Keywords |
Districting; Last-mile delivery; Postal delivery; Supply chain management; Heuristics |
| Abstract |
Last-mile logistics corresponds to the last leg of the supply chain, i.e., the delivery of goods to final cus-tomers, and they comprise the core activities of postal and courier companies. Because of their role in the supply chain, last-mile operations are critical for the perception of customers regarding the perfor-mance of the whole logistic process. In this sense, the sustained growth of e-commerce, which has been abruptly catalyzed by the irruption of the COVID-19 pandemic, has hanged the habits of customers and overtaxed the operational side of delivery companies, hindering their viability and forcing their adap-tation to the novel conditions. Many of these habits will remain after we overcome the sanitary crisis, which will permanently reshape the structure and emphasis of postal supply chains, demanding compa-nies to implement organizational and operational changes to adapt to these new challenges. In this work we address a last-mile logistic design problem faced by a courier and delivery company in Chile, although the same problem is likely to arise in the last-mile delivery operation of other postal companies, in particular in the operation of express delivery services. The operational structure of the company is based on the division of an urban area into smaller territories (districts) and the outsourcing of the delivery operation of each territory to a last-mile contractor. Because of the increasing volume of postal traffic and a decreasing performance of the service, in particular for the case of express deliveries, the company is forced to redesign its current territorial arrangement. Such redesign results in a novel optimization problem that resembles a classical districting problem with the additional quality of service requirements. This novel problem is first formulated as a mathematical programming model and then a specially tailored heuristic is designed for solving it. The proposed approach is tested on instances from the real-life case study, and the obtained results show significant improvements in terms of the percent-age of on-time deliveries achieved by the proposed solution when compared to the current districting design of the company. By performing a sensitivity analysis considering different levels of demand, we show that the proposed approach is effective in providing districting designs capable of enduring signifi-cant increases in the demand for express postal services. |
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0305-0483 |
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WOS:000809666900001 |
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UAI @ alexi.delcanto @ |
Serial |
1605 |
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| Author |
Melo, I.C.; Alves, P.N.; Queiroz, G.A.; Yushimito, W.; Pereira, J. |
| Title |
Do We Consider Sustainability When We Measure Small and Medium Enterprises' (SMEs') Performance Passing through Digital Transformation? |
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| Year |
2023 |
Publication |
Sustainability |
Abbreviated Journal |
Sustainability |
| Volume |
15 |
Issue |
6 |
Pages |
4917 |
| Keywords |
digitalization; small- and medium-sized enterprises (SMEs); Industry 4; 0; topic modeling; latent dirichlet allocation (LDA); triple bottom line of sustainability |
| Abstract |
Small-medium enterprises (SMEs) represent 90% of business globally. Digital Transformation (DT) affects SMEs differently from larger companies because although SMEs have more flexibility and agility for adapting to new circumstances, they also have more limited resources and specialization capabilities. Thus, it is fundamental to measure SMEs' performance considering different perspectives. Here, we describe and analyze the state-of-the-art of DT in SMEs, focusing on performance measurement. We center on whether the tools used by SMEs encompass the triple bottom line of sustainability (i.e., environmental, social, and economic aspects). To do so, in December 2021, we performed a comprehensive systematic literature review (SLR) on the Web of Science and Scopus. In addition, we also explored a novel approach for SLR: topic modeling with a machine learning technique (Latent Dirichlet Allocation). The differences and interchangeability of both methods are discussed. The findings show that sustainability is treated as a separate topic in the literature. The social and environmental aspects are the most neglected. This paper contributes to sustainable development goals (SDGs) 1, 5, 8, 9, 10, and 12. A conceptual framework and future research directions are proposed. Thus, this paper is also valuable for policymakers and SMEs switching their production paradigm toward sustainability and DT. |
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2071-1050 |
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WOS:000958416000001 |
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UAI @ alexi.delcanto @ |
Serial |
1770 |
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Melo, I.C.; Queiroz, G.A.; Junior, P.N.A.; de Sousa, T.B.; Yushimito, W.F.; Pereira, J. |
| Title |
Sustainable digital transformation in small and medium enterprises (SMEs): A review on performance |
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| Year |
2023 |
Publication |
Heliyon |
Abbreviated Journal |
Heliyon |
| Volume |
9 |
Issue |
3 |
Pages |
e13908 |
| Keywords |
Digitalization; Small and medium-sized enterprises (SMEs); Industry 40Triple bottom line (TBL) of sustainability; Sustainable development goals (SDG) |
| Abstract |
Small and medium enterprises (SMEs) are responsible for 90% of all business and 50% of employment globally, mostly female jobs. Therefore, measuring SMEs' performance under the digital transformation (DT) through methods that encompass sustainability represents an essential tool for reducing poverty and gender inequality (United Nations Sustainable Development Goals). We aimed to describe and analyze the state-of-art performance evaluations of digital transformation in SMEs, mainly focusing on performance measurement. Also, we aimed to determine whether the tools encompass the three pillars of sustainability (environmental, social, and economic). Through a systematic literature review (SLR), a search on Web of Science (WoS) and Scopus resulted in the acceptance of 74 peer-reviewed papers published until December 2021. Additionally, a bibliometrics investigation was executed. Although there was no time restriction, the oldest paper was published in 2016, indicating that DT is a new research topic with increasing interest. Italy, China, and Finland are the countries that have the most published on the theme. Based on the results, a conceptual framework is proposed. Also, two future research directions are presented and discussed, one for theoretical and another for practical research. Among the theoretical development, it is essential to work on a widely accepted SME definition. Among the practical research, nine directions are identified-e.g., applying big data, sectorial and regional prioritization, cross-temporal investigations etc. Researchers can follow the presented avenues and roads to guide their researchers toward the most relevant topics with the most urgent necessity of investigation. |
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2405-8440 |
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| Notes |
WOS:000968115200001 |
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| Call Number |
UAI @ alexi.delcanto @ |
Serial |
1782 |
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| Author |
Pereira, J.; Ritt, M. |
| Title |
Exact and heuristic methods for a workload allocation problem with chain precedence constraints |
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| Year |
2023 |
Publication |
European Journal Of Operational Research |
Abbreviated Journal |
Eur. J. Oper. Res. |
| Volume |
309 |
Issue |
1 |
Pages |
387-398 |
| Keywords |
Manufacturing; Assembly line balancing; Worker allocation; Dynamic programming; Branch and bound |
| Abstract |
Industrial manufacturing is often organized in assembly lines where a product is assembled on a se-quence of stations, each of which executes some of the assembly tasks. A line is balanced if the maximum total execution time of any station is minimal. Commonly, the task execution order is constrained by precedences, and task execution times are independent of the station performing the task. Here, we con -sider a recent variation, called the “(Calzedonia) Workload Allocation Problem” (WAP), where the prece-dences form a chain, and the execution time of a task depends on the worker executing it. This problem was recently proposed by Battarra et al. (2020) and it is a special case of the Assembly Line Worker As-signment and Balancing Problem Miralles et al. (2007) where precedence relations are arbitrary. In this paper we consider the computational complexity of the problem and prove its NP-hardness. To solve the problem, we provide different lower bounds and exact and heuristic procedures. The performance of the proposed methods is tested on previously proposed instances and on new, larger instances with the same characteristics. The results show that the proposed methods can solve instances with up to about 40 0 0 tasks and 29 workers, doubling the size of the instances that previously could be solved to optimality. |
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0377-2217 |
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| Notes |
WOS:000970067900001 |
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| Call Number |
UAI @ alexi.delcanto @ |
Serial |
1794 |
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