Design and balancing of assembly lines that minimize ergonomic risk

Minimización del Riesgo ergonómico de la línea de motores de Nissan-BCN en función del número de estaciones de trabajo.In this paper, an assessment system of the ergonomic hazards existing in the workstations of an assembly line is provided. A mathematic model to solve the assembly line balancing problem is developed with the aim of minimizing the ergonomic risk that exists in an assembly line by taking into account the number of workstations and a set of temporal and spatial restrictions. This model has been applied, by means of a computational experiment, in a problem taken from a case study of Nissan’s engine plant in Barcelona. The experiment measures the impact that the increase in the number of workstations causes on the improvement of the ergonomic quality of such workplaces and on the reduction of the ergonomic risk.Preprin

Pathophysiology, histopathology and therapeutic of SARS-CoV-2

The rapid transmission of SARS-CoV-2 through the world has induced the scientist to understand the histopathology of the virus and then to find an effective drug. However, many of the point associated with the virus pathogenicity still unknown and need more studies. In this chapter the pathophysiology, histopathology and therapeutic of SARS-CoV-2 has been reviewed. It was appeared that pathogenicity of SARS-CoV-2 is belonging to the viral with genome structure which acting by blocking the host innate immune response. Both chloroquine and hydroxyl-chloroquine have similar structure and mechanism action and they are among the most effective antiviral for treating the patents with the SARS-CoV-2. Chloroquine works by inhibition the intracellular organism by increasing the pH

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

A Relative Tolerance Relation of Rough Set (RTRS) for potential fish yields in Indonesia

The sea is essential to life on earth, including regulating the climate, producing oxygen, providing medicines, providing habitats for marine animals, and feeding millions of people. It must be ensured that the sea continues to meet the needs of life without sacrificing the people of future generations. The sea regulates the planet’s climate and is a significant source of nutrients. The sea becomes an essential part of global commerce, while the contents of the ocean become the solution of human energy needs today and the future. The wealth and potential of the sea as a source of energy for humans today and the future needs to be mapped and described to provide a picture of marine potential to all concerned. As part of the government, the Ministry of Marine Affairs and Fisheries is responsible for the process of formulating, determining, and implementing policies in the field of marine and fisheries based on the results of mapping and extracting information from existing conditions. The results of this information can be used to predict the marine potential in a marine area. This prediction process can be developed using data-mining techniques such as applying the association rule by looking at the relationship between the quantity of fish based on the plankton abundance index. However, this association rules data-mining techniques that require complete data, which are data sets with no missing values to generate interesting rules for detection systems. The problem is often that required marine data are not available or that marine data are available, but they contain incomplete data. To address this problem, this paper introduces a Relative Tolerance Relation of Rough Set (RTRS). Novelty RTRS differs from previous rough approaches that use tolerance relationships, nonsymmetric equation relationships, and limited tolerance relationships. The RTRS approach is based on a limited tolerance relationship considering the relative precision between two objects; therefore, this is the first job to use relative precision. In addition, this paper presents the mathematical approach of the RTRS and compares it with other existing approaches using the marine real dataset to classify the marine potential level of the region. The results show that the proposed approach is better than the existing approach in terms of accuracy

Profit-oriented disassembly-line balancing

As product and material recovery has gained importance, disassembly volumes have increased, justifying construction of disassembly lines similar to assembly lines. Recent research on disassembly lines has focused on complete disassembly. Unlike assembly, the current industry practice involves partial disassembly with profit-maximization or cost-minimization objectives. Another difference between assembly and disassembly is that disassembly involves additional precedence relations among tasks due to processing alternatives or physical restrictions. In this study, we define and solve the profit-oriented partial disassembly-line balancing problem. We first characterize different types of precedence relations in disassembly and propose a new representation scheme that encompasses all these types. We then develop the first mixed integer programming formulation for the partial disassembly-line balancing problem, which simultaneously determines (1) the parts whose demand is to be fulfilled to generate revenue, (2) the tasks that will release the selected parts under task and station costs, (3) the number of stations that will be opened, (4) the cycle time, and (5) the balance of the disassembly line, i.e. the feasible assignment of selected tasks to stations such that various types of precedence relations are satisfied. We propose a lower and upper-bounding scheme based on linear programming relaxation of the formulation. Computational results show that our approach provides near optimal solutions for small problems and is capable of solving larger problems with up to 320 disassembly tasks in reasonable time