Final Layout Research Articles

An elitist strategy genetic algorithm using simulated annealing algorithm as local search for facility layout design

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.

A linear time layout algorithm for business process models

The layout of a business process model influences how easily it can be understood. Existing layout features in process modeling tools often rely on graph representations, but do not take the specific properties of business process models into account. In this paper, we propose an algorithm that is based on a set of constraints which are specifically identified toward establishing a readable layout of a process model. Our algorithm exploits the structure of the process model and allows the computation of the final layout in linear time. We explain the algorithm, show its detailed run-time complexity, compare it to existing algorithms, and demonstrate in an empirical evaluation the acceptance of the layout generated by the algorithm. The data suggests that the proposed algorithm is well perceived by moderately experienced process modelers, both in terms of its usefulness as well as its ease of use.

A NOVEL ARCHITECTURE OF MAXIMUM POWER POINT TRACKING FOR ULTRA-LOW-POWER BASED HYBRID ENERGY HARVESTER IN UBIQUITOUS DEVICES: A REVIEW

This research work presents a novel architecture of an Ultra-Low-Power (ULP) based Hybrid Energy Harvester (HEH) consisting of multiple input sources such as kinetic, thermal and solar energy, harvested from passive human power. Having multiple ambient sources mitigates limitations caused by single sources especially for bodily-worn applications; however, this results in impedance mismatch among the different integrated sources. To overcome this limitation, the proposed ULP-HEH will use one power management unit with Maximum Power Point Tracking (MPPT) algorithm and impedance matching considerations to efficiently manage and combine power harvested from all three sources to achieve ULP consumptions. Among other crucial sub-modules of the ULP-HEH are its Asynchronous Finite State Machine (AFSM) cum resource sharing arbiter to prioritize and share energy sources for overall power reduction, an efficient rectification scheme for the piezoelectric input, an adaptive feedback for ULP conditioning, Zero-Current Switching (ZCS) for semi-lossless switching, a self-start circuit for low ambient startup, a Boost converter, a Buck regulator, a fuzzy-based micro-battery charger and a de-multiplexer to switch between harvesting or charging capabilities. All of which are implemented for maximum output extraction and minimal losses. This ULP-HEH will be developed in PSPICE software, Verilog coding under Mentor Graphics environment and later to be verified using Field Programmable Gate Array (FPGA) board before the final layout implementation in CMOS 0.13-µm process technology. This battery-less ULP-HEH is expected to deliver 3.0-5.0V of regulated voltage output from low ambient sources of 35 mV at startup. An efficiency of 90% with an output power of 650 µm is expected when all sources are summed. Also, this ULP-HEH is aimed at reducing power consumption to at least twice (

Coupled simulation of natural ventilation and daylighting for a residential community design

This investigation proposed a three-step design procedure to fully utilize natural ventilation with a performance simulation of daylighting. A residential community in Chongqing, China was taken as an example case to illustrate the design procedure from building level to floor level. The building spacing and orientation was optimized through outdoor velocity and pressure field simulation with computational fluid dynamics method. It was showed that the building pressure difference and unit pressure difference can increase for about 10–30% by changing the spacing and building orientation. With the shading and view shadow effect between buildings considered, a final building layout design was determined for the real terrain. Finally, the indoor air flow distribution and daylighting performance in a standard floor was predicted and optimized by modifying indoor floor planning. The result was used to provide suggestions on window allocation and indoor floor plan. The benefits of indoor air quality and energy consumption from natural ventilation were also discussed for Chongqing, China. A rough estimation showed that the energy saving potential of natural ventilation in Chongqing, China could be up to 40% in terms of electricity consumption.

Maximum macroseismic intensity map of Greece for the time period 1953–2011

The aim of this paper is to present the spatial distribution of macroseismic intensities assigned in modified Mercalli (MM) scale, across the Greek territory. For this purpose, a digital database with more than 30,000 local seismic intensity recordings from 156 major earthquake events that affected Greece and adjacent areas during the period 1953–2011 was developed. These events have focal depths up to about 150 km and surface-wave magnitudes (Ms) greater than 4.4. Various GIS-based techniques for data analysis and map creation were applied. A number of seismic intensity maps have been produced taking into account different attributes like intensities for shallow or deep events, maximum intensities by administrative units, maximum intensity for significant earthquakes, etc. The main map produced is the national map of maximum seismic intensities for shallow earthquakes (scale 1:1.500.000). The final layout also contains the maximum seismic intensities for deep earthquakes, the tectonic lines of Greece, the earthquakes of the database as well as the seismic intensities for two significant earthquakes in the last six decades.

Design of 6H-SiC High Temperature Pressure Sensor Chip

Over the last decade, a relatively in-depth research on the different structures and types of the full SiC pressure sensors including the piezoresistive, the capacitive and the optical SiC pressure sensors etc. has been conducted with a view to realizing the pressure measurement in high temperature circumstances. The piezoresistive SiC pressure sensor has gradually become the focus of research due to its simple structure and convenience application. In our research, the piezoresistance strip is designed on the deep-etching sensitive circular diaphragm formed via deep etching. Firstly, the 6H-SiC strain coefficient GF value is compared on the radial direction and the transverse direction by analyzing the circular diaphragm deformation theory. It’s concluded that both in the radial direction, four resistance strips are assigned in the center of circular diaphragm and along the edge respectively, with equal number on these two locations. Better consistency and sensitivity are achieved by this solution. Secondly, the design size of the sensitive circular diaphragm and the pressure resistance strips are determined with the expected work temperature and the target measuring range being taken into consideration. The final layout scheme design of four pressure resistance strips is determined through simulation on the consideration of the thermal stress caused by the AlN packaging.

A model to optimize facility layouts with toxic releases and mitigation systems

The possibility of including mitigation systems in layout models is explored in this work. The model is based on a previous work by the authors to estimate toxic concentrations around each releasing facility surrounded by a mitigation system. The mitigation systems considered here includes water, steam, and air curtains and exponential decays are assumed for the concentrations shapes before and after the installed curtain. The selection of the mitigation system type to install is included as a variable to determine when solving the proposed MINLP model. Additional constraints include the conventional non-overlapping and risk estimations based on probit functions. The objective function includes occupied land costs, interconnection costs, risk damage costs, and mitigation costs. A software package called TROL has been developed to automatically interact with GAMS and ease the initial and final layout descriptions. Numerical results indicate that the proposed model produces more practical and optimal layouts.

A Probabilistic Constraint Programming Model to Reduce Risk in Layouts with Toxic Release Scenarios

A probabilistic approach is used in this work to provide additional information on risk in optimal facility layouts. The probability distribution for risk is produced via Monte Carlo simulations where stochastic variables are varied according to their own distributions. LOPA procedure is applied to reduce risk to acceptable levels. Thus risk is adopted as a stochastic variable where extra information can be extracted to help decision makers in defining the final optimal layout. A case study reported in the literature is used here to demonstrate the advantages of applying the proposed approach when risk is analyzed using the LOPA procedure.

Key characteristics-based sensor distribution in multi-station assembly processes

This paper presents a novel approach for optimal key characteristics-based sensor distribution in a multi-station assembly process, for the purpose of diagnosing variation sources responsible for product quality defects in a timely manner. Current approaches for sensor distribution are based on the assumption that measurement points can be allocated at arbitrary locations on the part or subassembly. This not only presents challenges in the implementation of these approaches but additionally does not allow required product assurance and quality control standards to be integrated with them, due to lack of explicit relations between measured features and geometric dimensioning and tolerancing (GD&T). Furthermore, it causes difficulty in calibration of measurement system and increases the likelihood of measurement error due to the introduction of measurement points not defined in GD&T. In the proposed approach, we develop methodology for optimal sensor allocation for 6-sigma root cause analysis that maximizes the number of measurement points placed at critical design features called Key Characteristics (KCs) which are classified into: Key Product Characteristics and Key Control Characteristics and represent critical product and process design features, respectively. In particular, KCs have defined dimensional and geometric tolerances which provides necessary design reference model for process control and diagnosis of product 6-sigma variation faults. The proposed approach allows obtaining minimum required production system 6-sigma diagnosability. A feature-based procedure is proposed which includes Genetic Algorithm-based approach (allowing pre-defined KCs as the measurement points) and state-of-the-art approaches (unrestricted location of measurement points) to iteratively include arbitrary measurement points together with KCs in the final sensor layout. A case study of automotive assembly processes is used to illustrate the proposed feature-based approach.

Design, Simulation, and Construction of a Test Rig for Organic Vapors

A blow-down wind tunnel for real-gas applications has been designed, validated by means of dynamic simulation, and then built. The facility is aimed at characterizing an organic vapor stream, representative of the expansion taking place in organic Rankine cycle (ORC) turbines, by independent measurements of pressure, temperature, and velocity. The characterization of such flows and the validation of design tools with experimental data, which are still lacking in the scientific literature, is expected to strongly benefit the performance of future ORC turbines. The investigation of flow fields within industrial ORC turbines has been strongly limited by the unavailability of calibration tunnels for real-gas operating probes, by the limited availability of plants, and by restricted access for instrumentation. As a consequence, it has been decided to design and realize a dedicated facility, in partnership with a major ORC manufacturer. The paper thoroughly discusses the design and the dynamic simulation of the apparatus, presents its final layout, and shows the facility “as built”. A straight-axis planar convergent-divergent nozzle represents the test section for early tests, but the test rig can also accommodate linear blade cascades. The facility implements a blow down operating scheme, due to high fluid density and operating temperature, which prevent continuous operation because of the prohibitive thermal power required. A wide variety of working fluids can be tested, with adjustable operating conditions up to maximum temperature and pressure of 400 °C and 50 bar, respectively. Despite the fact that the test rig operation is unsteady, the inlet nozzle pressure can be kept constant by a control valve. In order to estimate the duration of the setup and experimental phase, and to describe the time evolution of the main process variables, the dynamic plant operation, including the control system, has been simulated. Design and simulation have been performed with both lumped-parameter and 1D models, using siloxane MDM and hydrofluorocarbon R245fa as the reference working fluids, described by state-of-the-art thermodynamic models. Calculations show how experiments may last from 12 seconds up to several minutes (depending on the fluid and test pressure), while reaching the experimental conditions requires few hours, consistently with the performance of daily-based experiments. Moreover, the economic constraints have been met by the technical solutions adopted for the plant, allowing the construction of the facility.

Conceptual Design of an Off-site Industrialization Process for FRP-based Transport Infrastructure Components

Fiber reinforced polymers (FRP) are used more and more in new construction structural components. Today already first transport infrastructures e.g. road and pedestrian bridges are built out of such components, using mainly manual and not automated manufacturing processes. In order to develop a cost-effective integrated construction process that will enable the maximum capability of automation of components for transport infrastructures using polymer based materials (carbon fiber, glass fiber, etc.) there is a need to industrialize the whole construction process of the FRP components.Hence the main objective is the conception and development of an automated off-site industrialization process for producing modular FRP-based transport infrastructure components. This overall process will cover the whole production process from the procurement of raw materials up to the transport of the produced components, including the facility layout and the management of involved human resources.This leads to the conceptual design of an off-site industrialization process for the most suitable highly flexible and agile production process at a high automation level as well as for coping different sizes and quantities of FRP components.Within this paper different planning activities for the conceptual design of the off-site industrialization process are presented and a detailed description of each planning phase and their associated planning activities is given. To define a conceptual design of the off-site industrialization process, the components that should be produced and the needed manufacturing processes are shortly presented. As a result of this for each component of the bridge, a generic production structure can be assigned and evaluated. Production areas, logistics as well as a rough layout for the factory have been analyzed and finally a variant for the possible final factory layout is presented.

Research on the General Keyboard Layout of Tibetan Numbers in Embedded System

This article mainly focused on the issues often encountered in input of embedded devices, and provided detailed analysis combined with successful experience of Tibetan QWERT keyboard layout, in accordance with the principles of ergonomics, quick-input. The layout of the digital keyboard has been done on the basis of this research. The Main research and analysis were: Selecting the most common corpus materials in Tibetan language (over 3.6million pieces) as the training set; Conducting cluster analysis with SPASS after integrating the importance and statistics of the corpus materials in Tibetan language; Improving the model with artificial intelligence method and obtaining the final model; IV Determining evaluation criteria. This design has complied the simulation for test input program, as well as selected different themes of the test corpus materials in Tibetan language for the simulated keyboard input process and obtained evaluation results. Eventually, through the analysis of the results, to determine the evaluation criteria of the final layout for the Tibetan digital keyboard.

Perancangan Fasilitas Pabrik Tahu untuk Meminimalisasi Material Handling

UD. Dhika Putra is a tahu manufacturing company. Currently, the company is having some problems in production facility layout and physical environment. This study aimed to redesign the facility layout of tahu manufacturing company to minimize the path length of material handling and apply the 55 method to enhance work productivity. The approach used to redesign the plant facility layout is Systematic Layout Planning (SLP), which can be categorized in three stages, namely material flow analysis, research, and selection. While the 55 method consist of several steps to organize workplace condition that affect on the effectiveness, eficiency, productivity, and safety. This study concluded that the chosen layout for the final layout showed a significant decrease in path length of material handling, i.e 45 meters or about 19,2%. The decreasing of material handling path length on the choosen layout was also influenced by the arrangement of the work place by using 55 method.

Full-scale and reduced-scale tests on smoke movement in case of car park fire

Full-scale and reduced-scale measurements along with numerical simulations have been carried out in order to increase fire safety in car parks, with particular focus on the smoke back-layering (SBL). SBL is the distance covered by the smoke upstream of the ventilation flow with respect to the fire source. It has been measured in both full- and reduced-scales and the results are compared to the literature. The investigated car park (full- and reduced-scale) has been simplified: ceiling and walls are plain and the final layout is similar to a very wide road tunnel. Horizontal and vertical beams supporting the ceiling are not considered. Therefore the results obtained are only valid for large closed parks with a flat ceiling and uni-directional smoke and ventilation patterns within the investigated heat release rate range. The study serves double purposes:Empirical formulae can be obtained and the best model for SBL can be chosen from the existing correlations for road tunnel fires to be applied to car parks with the above described simplified geometries.If the results of the reduced-scale car park model are in accordance with the full-scale ones, the reduced-scale model can be used for more complex car park layouts, which is a very favorable solution in terms of both time and costs.In addition to the SBL investigation, unexpected flow phenomena at the entrance and extractors, respectively, are also explained by reduced-scale trials.

Conceptual Design of Solar Powered Unmanned Arial Vehicle

The solar-powered aircraft represents a major step forward in environmentally friendly vehicle technology. An unmanned aircraft vehicle (UAV) was designed to fly for 24 hours continuously to achieve surveillance at low altitude. It is a lightweight, solar-powered, remotely piloted flying wing aircraft that is demonstrating the technology of applying solar power for long-duration and low-altitude flight. Several programs and codes were used in the designing process of the UAV and generating its layout. A MATLAB computer programming code was written to optimize on various values of aspect ratio (AR) and wingspan (b) after setting the mission requirements and estimating the technological parameters. A program called Java Foil was used to calculate the lift. Another program called RDS was used to obtain the final layout of the aircraft. The great benefit is that the design is general enough to be applied to different values of aspect ratio and wingspan. Moreover, the analytical form of the method allows identifying clear some general principles like the optimization on various values of aspect ratio and wingspan, and the calculation of the lift.

Modeling and simulation of 1 MWe solar tower plant’s solar flux distribution on the central cavity receiver

The solar flux distribution rule inside a central cavity receiver is of great significance to the safe operation of solar tower power plants. In this paper, a heliostat field model was fully developed to simulate the solar flux distribution on the inner surfaces of a cavity receiver of a solar tower power plant by means of the Monte-Carlo ray-tracing method. In addition, the mathematical modeling process that starts from the incident solar rays to the absorbed energy by the inner surfaces of the cavity receiver was presented in detail. According to the final layout of the heliostat field, a dynamic simulation of the solar flux inside the cavity receiver during the vernal equinox was performed. The results indicated that the incident energy reflected by the heliostat field was mainly distributed on the rear and lateral surfaces throughout the day. Moreover, at different time points, the solar flux distribution rule inside the cavity receiver was also analyzed in detail. In order to verify the validity of this model, the simulation results were taken to compare with the experimental data of a random heliostat. Furthermore, to further testify the accuracy of our model, the simulation results obtained by inputting the coordinates of the CESA-I’s heliostat field into our model were also taken to compare with the published experiment data. Ultimately, both of the comparative results show that they can be good references for the safe design of the whole system.

An elitist strategy genetic algorithm for integrated layout design

While designing the layout of any manufacturing organizations, the primary objective is to decide an optimal arrangement of their departments (machines or cells) in a two-dimensional shop floor (facility) satisfying desired objectives, which is termed facility layout problem (FLP). In traditional layout design philosophy, the inter-cell layout and flow path layout design of material handling system (MHS) was carried out step by step in a sequential manner. This results in sub-optimal solutions for FLP. In this paper, an integrated approach is adopted to design the inter-cell layout and the flow path layout of MHS simultaneously. The quality of the final layout is evaluated by minimizing the weighted sum of two distance-based cost objectives namely, (1) total material handling cost. (2) Distance-weighted cost of total closeness rating score. Sequence-pair (SP) representation is used for layout encoding. The translation from SP to layout is efficiently done by longest common subsequence methodology. Due to NP-hard nature of the proposed problem, an elitist strategy genetic algorithm (ESGA) is developed and tested with three test problem instances available in the literature. It is found that the proposed ESGA algorithm is able to produce the best solutions consistently, twice faster than the standard GA for the test problem instances.

Adaptive variable neighborhood search for solving multi-objective facility layout problems with unequal area facilities

In this paper, we report the results of our investigation of an evolutionary approach for solving the unequal area multi-objective facility layout problem (FLP) using the variable neighborhood search (VNS) with an adaptive scheme that presents the final layouts as a set of Pareto-optimal solutions. The unequal area FLP comprises a class of extremely difficult and widely applicable optimization problems arising in diverse areas and meeting the requirements for real-world applications. The VNS is an explorative local search method whose basic idea is systematic change of neighborhood within a local search. Traditionally, local search is applied to the solutions of each generation of an evolutionary algorithm, and has often been criticized for wasting computation time. To address these issues, the proposed approach is composed of the VNS with a modified 1-opt local search, an extended adaptive local search scheme for optimizing multiple objectives, and the multi-objective genetic algorithm (GA). Unlike conventional local search, the proposed adaptive local search scheme automatically determines whether the VNS is used in a GA loop or not. We investigate the performance of the proposed approach in comparison to multi-objective GA-based approaches without local search and augmented with traditional local search. The computational results indicate that the proposed approach with adaptive VNS is more efficient in most of the performance measures and can find near-optimal layouts by optimizing multiple criteria simultaneously.

Multidimensional Projections for Visual Analysis of Social Networks

Visual analysis of social networks is usually based on graph drawing algorithms and tools. However, social networks are a special kind of graph in the sense that interpretation of displayed relationships is heavily dependent on context. Context, in its turn, is given by attributes associated with graph elements, such as individual nodes, edges, and groups of edges, as well as by the nature of the connections between individuals. In most systems, attributes of individuals and communities are not taken into consideration during graph layout, except to derive weights for force-based placement strategies. This paper proposes a set of novel tools for displaying and exploring social networks based on attribute and connectivity mappings. These properties are employed to layout nodes on the plane via multidimensional projection techniques. For the attribute mapping, we show that node proximity in the layout corresponds to similarity in attribute, leading to easiness in locating similar groups of nodes. The projection based on connectivity yields an initial placement that forgoes force-based or graph analysis algorithm, reaching a meaningful layout in one pass. When a force algorithm is then applied to this initial mapping, the final layout presents better properties than conventional force-based approaches. Numerical evaluations show a number of advantages of pre-mapping points via projections. User evaluation demonstrates that these tools promote ease of manipulation as well as fast identification of concepts and associations which cannot be easily expressed by conventional graph visualization alone. In order to allow better space usage for complex networks, a graph mapping on the surface of a sphere is also implemented.

Selecting a pharmacy layout design using a weighted scoring system

A weighted scoring system was used to select a pharmacy layout redesign. Facilities layout design techniques were applied at a local hospital pharmacy using a step-by-step design process. The process involved observing and analyzing the current situation, observing the current available space, completing activity flow charts of the pharmacy processes, completing communication and material relationship charts to detail which areas in the pharmacy were related to one another and how they were related, researching applications in other pharmacies or in scholarly works that could be beneficial, numerically defining space requirements for areas within the pharmacy, measuring the available space within the pharmacy, developing a set of preliminary designs, and modifying preliminary designs so they were all acceptable to the pharmacy staff. To select a final layout that could be implemented in the pharmacy, those layouts were compared via a weighted scoring system. The weighted aspect further allowed additional emphasis on categories based on their effect on pharmacy performance. The results produced a beneficial layout design as determined through simulated models of the pharmacy operation that more effectively allocated and strategically located space to improve transportation distances and materials handling, employee utilization, and ergonomics. Facilities layout designs for a hospital pharmacy were evaluated using a weighted scoring system to identify a design that was superior to both the current layout and alternative layouts in terms of feasibility, cost, patient safety, employee safety, flexibility, robustness, transportation distance, employee utilization, objective adherence, maintainability, usability, and environmental impact.