Improving Optimization Solution for Facility Layout Problem with Thermal Comfort

The Facility Layout Problem (FLP) is a renowned and extensively researched problem that has attracted significant focus from various areas, including industry and manufacturing. One of the recent studies includes the examination of FLP issues in a large room. Analysing the layout of amenities and temperature controls in spacious areas like libraries is crucial for understanding how they affect people’s thermal comfort and energy consumption. The arrangement of facilities typically impacts the air distribution within a large room. Improper facility layout design might create indoor temperature disparities, with specific zones feeling excessively warm or chilly. Consequently, users are unevenly distributed due to each individual’s differing thermal comfort needs. Previous researchers have discussed this issue. However, after a detailed examination of previous studies, a few drawbacks have been identified in building mathematical models. These drawbacks include poorly organised mathematical modelling, ambiguous or disorganised data collection and analysis techniques, and the absence or ambiguity of variables and constraints. Therefore, this study proposed a structured mathematical approach to build a more efficient, inclusive, and reliable model. This study used a university library in Malaysia as a case study. A well-established and widely practised method for assessing mathematical modelling competency based on previous research has been adopted. Subsequently, the list of sub-competencies associated with the modelling process is utilised as a reference point for constructing a mathematical model in this research endeavour. As a result, the entire process of constructing a mathematical model is detailed, and recommendations for future enhancements are provided. This project is considered a significant advancement in the pursuit of conducting further FLP investigations in large rooms for the greater good in the future, which is part of the PhD research carried out at UUM.

The Single-Row Facility Layout Problem (SRFLP) is one of the most studied facility layout problems in the literature. It asks for an optimal arrangement of departments with given lengths on a row such that the weighted sum of all centre-to-centre distances between department pairs is minimised. Real-world facility layouts may require taking different restrictions on the placement of departments into account, such as arrangement on a fixed position, pairwise placement, or precedence considerations. Therefore, we consider the constrained Single-Row Facility Layout Problem (cSRFLP) that additionally considers positioning, ordering, and relation constraints on single-row facility layouts. In this work, we suggest a new Integer Linear Programming (ILP) formulation for the cSRFLP, which outperforms the best available exact approach in literature. In an extensive computational study, we apply our ILP approach as well as an LP-based cutting plane algorithm on SRFLP and cSRFLP instances from the literature. We provide optimal cSRFLP layouts as well as strong lower bounds for instances with up to 42 departments. Further, we present new results for SRFLP instances from the literature. Additionally, we demonstrate the individual impact of the constraint sets on the run times of cSRFLP instances to emphasise further research on this rarely studied practice-oriented Facility Layout Problem.

ABSTRACTIn manufacturing industries, the facility layout design is a very important task, as it is concerned with the overall manufacturing cost and profit of the industry. The facility layout problem (FLP) is solved by arranging the departments or facilities of known dimensions on the available floor space. The objective of this article is to implement the firefly algorithm (FA) for solving unequal-area, fixed-shape FLPs and optimizing the costs of total material handling and transportation between the facilities. The FA is a nature-inspired algorithm and can be used for combinatorial optimization problems. Benchmark problems from the previous literature are solved using the FA. To check its effectiveness, it is implemented to solve large-sized FLPs. Computational results obtained using the FA show that the algorithm is less time consuming and the total layout costs for FLPs are better than the best results achieved so far.

The most desirable characteristic of a facility layout is its ability to maintain its efficiency over time while coping with the uncertainty in product demand. In the traditional facility layout design method, the facility layout is governed by the flow intensity between departments, which is the product flow quantity between departments. Hence, an error in the product demand assessment can render the layout inefficient with respect to material handling costs. Most of the research integrates uncertainty in the form of probability of occurrence of different from-to charts. In an environment where the variability of each product demand is independent, the derivation of ‘probabilistic from-to chart’ based scenario cannot be used to address uncertainty of individual demands. This paper presents an FLP (facility layout problem) approach to deal with the uncertainty of each product demand in the design of a facility layout. Two procedures are presented: the first procedure is utilised to assess the risk associated with the layout, while the second procedure is used to develop the layout that minimises the risk. Results from case studies have shown that the procedure produces a reduction of risk as high as 68%.

HVAC systems account for 50% of buildings’ energy use and could play a critical role in energy management in buildings both for energy-saving, and demand-side management to reduce peak energy use. According to contextual demands of occupants, efficient control of HVAC systems could result in peak energy saving and decreased energy costs in demand response programs. Accordingly, in this paper, we have introduced an agent-based model consisting of three agents: human agent, thermostat agent, and utility agent. In this model, the thermostat agent receives the real-time electricity price from the utility agent and aggregates thermal comfort profiles of the occupants from human agents. By considering these inputs, the thermostat agent employs a predictive model of a house and calculates the next set point of the HVAC system on energy cost and occupants’ comfort. Then, the thermostat agent signals the suggested set point to the thermostat of the building at each time step. For evaluating the proposed controller’s performance, the electricity price profile from ERCOT, which supplies the state of Texas, is used as a signal from the utility agent. Realistic thermal comfort data were used to simulate the thermal preference of occupants represented as human agents. The evaluation was carried out in a co-simulation using a Python and EnergyPlus model of a residential unit. Our results show that the proposed controller reduces the peak energy by 5.5% to 10% and increases occupants’ thermal satisfaction up to 12%. The main contribution of this paper is developing an agent-based model that humans, as the main stakeholders of the buildings, play a role in controlling HVAC systems for peak reduction and energy saving.

Facility layout problems deal with layout of facilities or departments in a shop floor. This article studies unequal-area static facility layout problems in order to minimize the sum of the material handling costs and unequal-area dynamic facility layout problems so as to minimize the sum of the material handling costs and rearrangement costs. Unequal-area static and dynamic facility layout problems are NP-hard. Therefore, a modified particle swarm optimization was suggested to solve them where the departments have fixed shapes and areas throughout the time horizon. The modified particle swarm optimization was tested using the available problem instances chosen from the literature. The proposed algorithm applied two local search methods and the department swapping method to improve the quality of solutions and to prevent local optima for dynamic and static problems. It also utilized the period swapping method to improve the solutions for dynamic problems. The results showed that the proposed algorithm has created encouraging layouts in comparison with other approaches.

Genetic search for solving construction site-level unequal-area facility layout problems

The facility layout problems are always important in the production or service industry system. For many years, it has been a common research field in active research. It seen that various methods were used in literature review for improving facility layout. We used association analysis which is one of the techniques of data mining in this study. The primary aim of this study is to improving the emergency department's efficiency, increasing patient satisfaction and employee satisfaction, decreasing travelled distance in emergency department. In this study, data acquired from information system of an emergency service was examined by means of data mining techniques (association rules such as GRI and Apriori) and relations between departments were found out. Association rules were analyzed via data mining techniques applied and then departments having more flow density with each other were determined. In consideration of this information an alternative facility layout planning was planned in regard to analysis results of departments’ closeness situations, advices of emergency service doctor and observations made.

This paper focuses on facility layout design problem in microfluidic device manufacturing. Microfluidics device manufacturing requires exquisite work of operators and relatively much higher material cost than other types of manufacturing. Facility layout problem can directly affect the overall cost of manufacturing, particularly in handling and transport cost. Therefore, the objective of this study is to minimize the total handling and transport cost for facility layout design problem. A genetic algorithm (GA) is employed to find a good alternative facility layout design which is based on the performance metrics. Experimental results show that this approach is more feasible in dealing with the facility layout in microfluidics device fabrication.

The facility layout design has been regarded as the key to improve plant productivity, which are relevant to both manufacturing and service sectors. Facility Layout Problems (FLPs) are known to be NP-hard problems; various optimization approaches for small problems and heuristic approaches for the larger problems have been proposed to elucidate the problem. A mathematical model is developed for the unequal size facility layout problem with fixed flow between departments. We are considering the orientations of the departments with various sizes and aims to minimize the distance traveled by people, material, and other supporting services in the safest and most effective manner. Some of the constraints considered in the modeling are the restricted areas, reserved departmentry locations, and also the irregularity of the shapes of manufacturing layout. This paper focuses on the mathematical model and the solution of the non-quadratic assignment problem (non-QAP) by hybridizing the meta-heuristic methods i.e. Genetic Algorithm (GA) and Simulated Annealing (SA). This work could be used in future as a reference for those researchers interested in tackling this challenging unequal facility layout problem.

The quality of facility layout is related to the operational efficiency of the entire system. Based on bibliometric methods, 859 related papers on the theme of facility layout included in the Web of Science core dataset from 2002 to 2021 were analyzed. First, through the visualization tools of Web of Science, the issue of facility layout is analyzed from the annual publication volume, journals and research directions. Next, based on the Citespace software, the cooperation and citation relationships among countries, institutions, and authors are analyzed from the macro, meso, and micro levels, and the cooccurrence analysis of keywords and nominal terms is carried out to generate a visual knowledge map, and to solve the problem of facility layout. The research status, hotspots and trends are reviewed. The results show that the problem of facility layout has been a hot research area. However, there are many and scattered situations in China's facility layout research, and it is necessary to strengthen cooperation. In addition, there are few studies in the fields of digital facility layout, smart factory, and digital twin, which need to be focused on.

A well-planned arrangement of manufacturing departments on a two-dimensional planar region considerably increases the efficiency of its production systems, which is termed facility layout problem (FLP). Conventional layout design approach often designs intercell layout (determining exact location of each department on shop floor area) and flow path layout design of material handling system (MHS) step by step in a sequential manner. This results in suboptimal solutions for FLP. In this paper, an integrated approach is adopted to design the intercell layout and the flow path layout of MHS simultaneously. The quality of the final layout is evaluated by minimizing total material handling cost. Sequence pair (SP) representation is used for layout encoding. The translation from SP to layout is efficiently made by longest common subsequence (LCS) methodology. An elitist strategy genetic algorithm using simulated annealing (E-GASAA) as a local search mechanism is developed and tested with four test problem instances available in the literature. Elitist strategy is incorporated to enhance convergence characteristic of the proposed algorithm. It is found that the proposed E-GASAA is able to produce best solutions consistently for the test problem instance of different sizes within acceptable computational effort. In addition to that, we tried to reduce the computational load with the help of adopted LCS computation methodology and achieved a good improvement.

Layout decisions represent an important step in production planning as they significantly affect the efficiency of a facility. They typically follow after make-or-buy decisions and capacity planning of a firm, and belong to the lowest level in the hierarchy of tactical production decisions. Sequential decision making neglects however the potential interaction between consecutive planning levels and may lead to inefficiencies. We propose an approach to a simultaneous make-or-buy decision making and facility layout planning in the presence of multiple products. To this end, we introduce a generalization of the classical quadratic assignment problem that takes into account (i) the costs of outsourcing, and (ii) the impact of layout decisions on the production costs of individual products. We further propose a solution approach based on the linearization of the resulting model and derive basic properties of the optimal planning decisions.

This paper proposes a new heuristic approach for solving facility layout problem (FLP) which is traditionally formulated as quadratic assignment problem (QAP). In this paper, FLP is formulated as linear assignment problem (LAP) consisting of facility pair and location pair. Being linear in nature LAP can be solved efficiently. Solution of LAP provides lower bound on corresponding QAP formulation of FLP. Heuristic procedure is applied to solve FLP from sets of LAP solution. Proposed heuristic is tested on benchmark instances taken from literature and compared with other heuristics available in literature. Computational results show that proposed heuristic provides a good quality approximate solution. This solution can be taken as initial solution for any improvement heuristic to get optimal/near optimal solution for FLP.

In the global competition, it is vital for any organization to minimize the cost of manufacturing or services and at the same time maintain the quality of process. Facility layout problem (FLP) is an important consideration to reduce the material-handling cost and thus improve the productivity. Optimal design and arrangement of facilities have a significant effect on the overall production cost and manufacturing lead time. In this work, the existing process type layout is studied and its transportation cost is determined. The tool SLP (systematic layout planning) is used to propose a new improved layout. As a part of research work, the existing facility layout of IWAI electronics, which is a speaker manufacturing industry, has been studied. The important parameter considered to improve the layout is the relationship between the departments. Computerized Relationship Layout Planning (CORELAP) was used analytically to investigate the total closeness rating (TCR) for the existing layout. The TCR helps to reposition the departments according to their relationship and closeness ranking. A new layout is then proposed which reduced the material-handling cost by 11.63%.