Incorporating working conditions to a mixed- model sequencing problem

Partiendo de una variante de un problema de secuenciación en líneas de productos mixtos (MMSP-W: Mixed-Model Sequencing Problem with Workload Minimisation), se proponen dos nuevos modelos que incorporan condiciones laborales a los puestos de trabajo de la línea. El primero tiene en cuenta la limitación de la saturación de los puestos de trabajo, mientras que el segundo contempla, además, la activación de los operarios a lo largo de la jornada laboral. Se realizan sendas experiencias computacionales, empleando un caso de estudio de la planta de motores de Nissan en Barcelona, con dos propósitos: (1) estudiar la repercusión que ocasiona la limitación de la saturación sobre la caída de la productividad de la línea, y (2) evaluar la recuperación de la productividad de la línea, mediante la activación de los operarios, manteniendo la misma calidad en las condiciones laborales conseguida al limitar la saturación.Beginning with a variation of the sequencing problem in a mixed-products line (MMSP-W: Mixed-Model Sequencing Problem with Workload Minimization), we propose two new models that incorporate the working conditions into the workstations on the line. The first model takes into account the saturation limit of the workstations, and the second model also includes the activation of the operators throughout the working day. Two computational experiments were carried out using a case study of the Nissan motor plant in Barcelona with two main objectives: (1) to study the repercussions of the saturation limit on the decrease in productivity on the line and (2) to evaluate the recovery of productivity on the line via activation of operators while maintaining the same quality in working conditions achieved by limiting the saturation. The obtained results show that the saturation limitation leads to suppose an important increase of work overload, which means average economic losses of 28,731.8 euros/day. However, the consideration of activity reduces these losses by 62.7%.Preprin

Minimisation des retards dans le séquencement des véhicules sur une ligne d'assemblage multi modèles

National audienceDans cet article, nous considérons le problème du séquencement sur une ligne d'assemblage à transport continu de véhicules industriels. Pour équilibrer au mieux la charge dynamique, nous proposons de minimiser les retards à l'issue de chaque véhicule. Nous proposons une formalisation par un modèle de type programmation linéaire. Le modèle est testé sur des instances du cas d'étude de l'usine de montage de Renault Trucks à Bourg en Bresse

Local order scheduling for mixed-model assembly lines in the aircraft manufacturing industry

Multi-variant products to be assembled on mixed-model assembly lines at locations within a production network need to be scheduled locally. Scheduling is a highly complex task especially if it simultaneously covers the assignment of orders, which are product variants to be assembled within a production period, to assembly lines as well as their sequencing on the lines. However, this is required if workers can flexibly fulfill tasks across stations of several lines and, thus, capacity of workers is shared among the lines. As this is the case for final assembly of the Airbus A320 Family, this paper introduces an optimization model for local order scheduling for mixed-model assembly lines covering both assignment to lines as well as sequencing. The model integrates the planning approaches mixed-model sequencing and level scheduling in order to minimize work overload in final assembly and to level material demand with regard to suppliers. The presented model is validated in the industrial application of the final assembly of the Airbus A320 Family. The results demonstrate significant improvement in terms of less work overload and a more even material demand compared to current planning

Interpretive Structural Modelling for Challenging Issues in JIT Supply Chain: Product Variety Perceptive

The success of JIT in Japan inspired many organizations to adopt JIT to the supply chain in order to reduce the waste and cost. These organizations have to face inherent challenging issues and complexities while implementing JIT concepts in supply chain. The manufacturer must be in position to identify challenging issues, its consequences so as to design a robust and reliable supply chain accordingly otherwise the manufacturing system may not provide the desired results. The focus of this paper is on the significant challenging issues in JIT supply chain from product variety perspective. Some challenging issues act as driver for sustainable implementation of JIT supply chain. For adoption of JIT supply chain, significant issues must be identified, analysed and discussed. In this research, study factors are the challenging issues for sustainable JIT supply chain implementation. Authors have identified ten significant issues from literature review. The main objectives are to identify and rank the challenging issues for implementation, to develop and to analysed the interaction between identified challenging issues using ISM and to prepare a framework for successful JIT supply chain implementation

Performance analysis of SWOT suite toolkit on Inter-domain and Intra-domain Web of Things

The Web of Things (WoT) is a term used to describe approaches, software architectural styles and programming patterns that allow real-world objects to be part of the World Wide Web [1]. Similarly to what the Web (Application Layer) is to the Internet (Network Layer), the Web of Things provides an Application Layer that simplifies the creation of Internet of Things applications [2]

Tahap penggunaan pembelajaran maya dalam kalangan guru reka bentuk teknologi: satu tinjauan di sekolah rendah luar bandar

Sejajar dengan matlamat anjakan ketujuh dalam Pelan Pembangunan Pendidikan Malaysia (2013-2025) iaitu untuk mentransformasikan sistem pendidikan negara, kerajaan telah menyediakan akses internet dan persekitaran pembelajaran maya melalui 1BestariNet di 10,000 sekolah seluruh Malaysia termasuk sekolah-sekolah luar bandar. Pembelajaran Maya (Virtual Learning Environment - VLE) merupakan platform pembelajaran yang menjadi agenda utama terutamanya di sekolah rendah. Secara spesifiknya, platform VLE Frog telah digunakan dalam kalangan guru dan pelajar sekolah rendah. Sehubungan itu, kajian berbentuk tinjauan ini dijalankan untuk mengkaji tahap penggunaan VLE Frog dalam aktiviti Pengajaran dan Pembelajaan (PdP) bagi subjek Reka Bentuk Teknologi (RBT) di sekolah rendah luar bandar. Selain itu, kajian ini juga bertujuan untuk mengkaji masalah utama yang dihadapi oleh guru-guru yang menggunakan VLE Frog di dalam aktiviti PdP. Responden yang terlibat dalam kajian ini adalah seramai 36 guru yang mengajar mata pelajaran RBT di 18 buah sekolah rendah luar bandar di daerah Batu Pahat. Borang soal selidik digunakan sebagai instrumen untuk proses pengumpulan data. Hasil kajian menunjukkan bahawa tahap penggunaan VLE Frog dalam kalang guru yang mengajar mata pelajaran RBT di sekolah luar bandar di Daerah Batu Pahat adalah serdehana. Selain itu, kajian ini juga mengunjukkan bahawa capaian internet merupakan masalah utama yang dihadapi oleh guru RBT semasa menggunakan VLE Frog di sekolah

Minimisation des retards dans le séquencement des véhicules sur une ligne d'assemblage multi modèles

National audienceDans cet article, nous considérons le problème du séquencement sur une ligne d'assemblage à transport continu de véhicules industriels. Pour équilibrer au mieux la charge dynamique, nous proposons de minimiser les retards. Nous proposons une formalisation par un modèle de type programmation linéaire. Un modèle monoposte est présenté puis une généralisation sur le cas multipostes est proposée. Le modèle est testé sur des instances du cas d'étude de l'usine de montage de Renault Trucks à Bourg en Bresse et une étude expérimentale des facteurs de complexité est développée

Infectious Disease Ontology

Technological developments have resulted in tremendous increases in the volume and diversity of the data and information that must be processed in the course of biomedical and clinical research and practice. Researchers are at the same time under ever greater pressure to share data and to take steps to ensure that data resources are interoperable. The use of ontologies to annotate data has proven successful in supporting these goals and in providing new possibilities for the automated processing of data and information. In this chapter, we describe different types of vocabulary resources and emphasize those features of formal ontologies that make them most useful for computational applications. We describe current uses of ontologies and discuss future goals for ontology-based computing, focusing on its use in the field of infectious diseases. We review the largest and most widely used vocabulary resources relevant to the study of infectious diseases and conclude with a description of the Infectious Disease Ontology (IDO) suite of interoperable ontology modules that together cover the entire infectious disease domain

Balancing and Sequencing of Mixed Model Assembly Lines

Assembly lines are cost efficient production systems that mass produce identical products. Due to customer demand, manufacturers use mixed model assembly lines to produce customized products that are not identical. To stay efficient, management decisions for the line such as number of workers and assembly task assignment to stations need to be optimized to increase throughput and decrease cost. In each station, the work to be done depends on the exact product configuration, and is not consistent across all products. In this dissertation, a mixed model line balancing integer program (IP) that considers parallel workers, zoning, task assignment, and ergonomic constraints with the objective of minimizing the number of workers is proposed. Upon observing the limitation of the IP, a Constraint Programming (CP) model that is based on CPLEX CP Optimizer is developed to solve larger assembly line balancing problems. Data from an automotive OEM are used to assess the performance of both the MIP and CP models. Using the OEM data, we show that the CP model outperforms the IP model for bigger problems. A sensitivity analysis is done to assess the cost of enforcing some of the constraint on the computation complexity and the amount of violations to these constraints once they are disabled. Results show that some of the constraints are helpful in reducing the computation time. Specifically, the assignment constraints in which decision variables are fixed or bounded result in a smaller search space. Finally, since the line balance for mixed model is based on task duration averages, we propose a mixed model sequencing model that minimize the number of overload situation that might occur due to variability in tasks times by providing an optimal production sequence. We consider the skip-policy to manage overload situations and allow interactions between stations via workers swimming. An IP model formulation is proposed and a GRASP solution heuristic is developed to solve the problem. Data from the literature are used to assess the performance of the developed heuristic and to show the benefit of swimming in reducing work overload situations