1,721,014 research outputs found
TeMA: A Tensorial Memetic Algorithm for Many-Objective Parallel Disassembly Sequence Planning in Product Refurbishment
Full text linkThe refurbishment market is rich in opportunities—the global refurbished smartphones market alone will be $38.9 billion by 2025. Refurbishing a product involves disassembling it to test the key parts and replacing those that are defective or worn. This restores the product to like-new conditions, so that it can be put on the market again at a lower price. Making this process quick and efficient is crucial. This paper presents a novel formulation of parallel disassembly problem that maximizes the degree of parallelism, the level of ergonomics, and how the workers' workload is balanced, while minimizing the disassembly time and the number of times the product has to be rotated. The problem is solved using the Tensorial Memetic Algorithm (TeMA), a novel two-stage many-objective (MaO) algorithm, which encodes parallel disassembly plans by using third-order tensors. TeMA first splits the objectives into primary and secondary on the basis of a decision-maker's preferences, and then finds Pareto-optimal compromises (seeds) of the primary objectives. In the second stage, TeMA performs a fine-grained local search that explores the objective space regions around the seeds, to improve the secondary objectives. TeMA was tested on two real-world refurbishment processes involving a smartphone and a washing machine. The experiments showed that, on average, TeMA is statistically more accurate than various efficient MaO algorithms in the decision-maker's area of preference
Evolution from BCS superconductivity to Bose condensation: Calculation of the zero-temperature phase coherence length
No full textWe consider a fermionic system at zero temperature interacting through an effective nonretarded potential of the type introduced by Nozières and Schmitt-Rink, and calculate the phase coherence length ..
Evolution from BCS superconductivity to Bose condensation: Role of the parameter kF-Xi
No full textWe argue that the natural variable to establish the crossover from Cooper-pair-based superconductivity to Bose-Einstein condensation of bound-electron pairs ..
Pareto-based optimization using a genetic algorithm in disassembly line balancing problem
No full textThe disassembly process assumes a great importance in the industrial reality, as product recovery is nowadays mandatory from the environmental point of view and for the law regulations. Solving the Disassembly Line Balancing Problem (DLBP) ensures the implementation of efficient and properly balanced lines. This paper presents an approach to determine the Pareto-optimal solutions for a bi-objective version of the DLBP using a genetic algorithm. The first objective is to maximize the disassembly sequence feasibility, by relaxing the constraint of precedence relationships between tasks to better explore the solution space. The second objective is to maximize the global profit, by means of a cost model that includes workstations, equipment, workers involved in the process, disposal costs and the revenues obtained by recovering recycled materials and spare parts. The system was tested by simulating different configurations involving the disassembly of an LCD. The results demonstrated the effectiveness of the system in finding Pareto-optimal solutions in all configurations
Evolution from BCS superconductivity to Bose condensation: analytic results for the crossover in three dimensions
No full textWe provide an analytic solution for the mean-field equations and for the relevant physical quantities at the Gaussian level, in terms of the complete elliptic integrals of the first and second kinds, for the crossover problem from BCS superconductivity to Bose-Einstein condensation of a three-dimensional system of free fermions interacting via an attractive contact potential at zero temperature. This analytic solution enables us to follow the evolution between the two limits in a particularly simple and transparent way, as well as to verify the absence of singularities during the evolution
A human-centric system combining smartwatch and LiDAR data to assess the risk of musculoskeletal disorders and improve ergonomics of Industry 5.0 manufacturing workers
No full textMore than one in four workers reportedly suffer from back pain worldwide, leading to 264 million work days lost yearly. In the U.S. alone, it causes 100 billion if including decreased productivity and lost wages. The upcoming Industry 5.0 revolution will introduce human-centric manufacturing systems where workers’ well-being comes first while safeguarding their rights: privacy, autonomy, and human dignity. This paper presents a privacy-preserving system based on artificial intelligence that tracks the posture of assembly/disassembly line workers while performing typical standardized tasks on repeat: connecting and separating parts; screwing and unscrewing using an electric screwdriver; tin soldering and unsoldering. The proposed solution assesses the upper-body (dominant arm, dominant shoulder, and trunk) and lower-body (legs) postures according to the ISO 11226 European standard, based on inertial data recorded by a smartwatch and using Laser imaging Detection and Ranging (LiDAR), respectively. These techniques preserve privacy as they collect data that cannot reveal the worker’s identity or sensitive information. Experiments showed that the system recognized a worker’s posture with a mean accuracy close to 98%. The system could help detect bad posture habits and reduce the chances of musculoskeletal disorders while preserving the workers’ privacy, in compliance with the upcoming Industry 5.0 paradigm
Analytic results for the crossover from BCS superconductivity to Bose-Einstein condensation
No full textWe provide analytic expressions for a number of physical quantities at zero temperature in three dimensions,
both at the mean-field level and with the inclusion of Gaussian fluctuations, for the problem of the crossover from
BCS superconductivity to Bose-Einstein condensation, in terms of the elliptic integrals
Universal behaviour within the Nozières Schmitt-Rink theory
No full textWe show that the natural variable to follow the crossover from Cooper-pair-based superconductivity to Bose-Einstein condensation within the model of Nozières and Schmitt-Rink is the product ..
End-of-life product disassembly with priority-based extraction of dangerous parts
Full text linkThe amount of electronic waste generated in the world is impressive. The USA alone yearly throw away 9.4 million tons of electronic devices: only 12.5% is recycled. One way to reduce this massive impact on the environment is to disassemble these devices with the aim of reusing and recycling as many parts as possible. Disassembling end-of-life products is a complex industrial process that may pose workers at risk because some parts of the product may contain dangerous materials. It is thus crucial to design efficient, sustainable and secure disassembly lines. This paper presents a multi-objective formulation of the Disassembly Line Balancing Problem (DLBP) which promotes efficiency and includes a new objective that increases the level of safety. The efficiency is guaranteed by balancing the idle times of the workstations, and by maximizing the profit and the level of feasibility of a disassembly sequence, which means disassembling the product as much as possible. Safety is maximized by extracting each dangerous part with a priority that is higher the more dangerous the part is. The most dangerous parts can thus be quickly removed from the product, thereby eliminating the exposure to the greatest risks. The disassembly continues with the execution of the tasks that remove the parts that are gradually less dangerous. Along with the DLBP formulation, this paper presents a genetic algorithm purposely designed to solve the problem. Two real-world case studies are discussed which entail the disassembly of a TV monitor and an air conditioner
- …
