Block Layout Research Articles

A simulation-based approach for the optimal design of signalling block layout in railway networks

To meet the growing demand in railway transportation, practitioners are more and more required to upgrade or substitute the signalling system in order to increase the capacity of the network. Existing approaches for the design of the signalling layout, usually tend to maximize the technological efficiency of the system by shortening the length of block sections, thus reducing the minimum line headway and the energy consumption but increasing investment costs. This paper presents a design approach addressed to identify the signalling layout which minimizes the investment and management costs, while respecting the required level of capacity. To solve this problem an innovative design framework is introduced which integrates a stochastic multi-train simulation model within a “black-box” optimization loop. Results obtained from an application to a real metro line confirm the effectiveness of such method in finding the solution which minimizes total costs for the line manager. A comparison with the block layout which maximizes the technological efficiency highlights that the obtained solution constitutes a satisfying trade-off between total costs and network performances.

Relative, but not absolute, thinning responses decline with increasing thinning age in a Eucalyptus nitens plantation

SummaryGrowth rates of trees and stand structure change as stands age, and therefore absolute and relative thinning responses may also vary with thinning age. The study examined whether thinning age influenced the relative and absolute thinning responses in Eucalyptus nitens plantations near Carrajung, Victoria, Australia, and whether this effect was influenced by nitrogen (N) fertiliser application. Two levels of thinning and fertiliser application were applied in a factorial design replicated three times in a randomised block layout in each of two trials established in September 2006 in adjacent plantations aged 3.2 y and 13.2 y respectively and from the same seed source. Treatments included: unthinned or thinned non-commercially from below to 300 trees ha–1; fertiliser treatments were nil or 300 kg ha–1 N as urea in the younger trial and nil or mixed fertiliser supplying 256 kg ha–1 N, 80 kg ha–1 P and 100 kg ha–1 K in the older trial. Five years after thinning, basal areas of the largest 200 sawlog crop trees ha–1 (SCTs) were about 4.1 m2 ha–1 greater in thinned than in unthinned stands, regardless of thinning age, and volumes of SCTs were 30.1 m3 ha–1 greater in thinned stands. As a result of the greater standing basal area and volumes in the older trial, relative thinning responses of SCTs were greater in the younger trial, such that thinning increased the basal area of the SCT200 by about 42% (and volume by 32%) in the younger trial, but by only 21% (and volume by 17%) in the older trial. Fertiliser application also increased absolute thinning responses. Smaller relative thinning responses in the older stand were associated with age-related changes in stand structure of unthinned stands, including increasing skewness and decreasing kurtosis of diameter distributions as stands aged. The absence of a thinning-age effect on absolute responses suggests that there is some flexibility in the thinning age in E. nitens plantations. However, it is important to note that while the absolute thinning response may be slow to decline, the size of the SCTs will be smaller after later-age thinning owing to the extended period of competition they experience prior to thinning.

An HCI Spatial Layout and Planning Technique for Ship Curved Block Construction

According to the study on the information technology status of domestic shipbuilding industry, aiming as the demand of full-vision and effective management mode of curved block construction scheduling, the HCI (Human-computer Interaction) spatial layout and planning technique of curved block is proposed. Through Several technical points and rich-client application, the graphics vector modeling of curved block and the dual-dimension block layout and planning dynamic display technology are achieved, then on these bases an HCI scheduling management technology with graphics transformation as core is put forward. Finally, a prototype system was designed and developed to verify in practice.

An exact and a simulated annealing algorithm for simultaneously determining flow path and the location of P/D stations in bidirectional path

Abstract In this paper, we present two algorithms to design flow path and the location of its pickup and delivery (P/D) stations simultaneously in a block layout for Automated Guided Vehicles (AGVs). We develop two algorithms to solve this problem. The first one is a cutting-plane algorithm to solve the mixed integer linear program that models the problem. The second one is a Simulated Annealing (SA) approach which solves the problem heuristically to a near best solution. Computational results show the performance of both algorithms.

On the effectiveness of Monte Carlo simulation and heuristic search for solving large-scale block layout problems

The effectiveness of Monte Carlo simulation relative to intelligent search strategies for solving block layout problems is investigated. For testing purposes, 810 block layout problems are constructed to span a wide range of problem sizes, material flow variation levels, work centre space requirements distributions, and work centre shape distributions. Contrary to preliminary results reported in earlier studies, greedy search and simulated annealing consistently outperform Monte Carlo Simulation across the full range of test problems and sample sizes. This divergence is explained through a comparison based on probabilistic derivations between the proportion of good solutions sampled by the Monte Carlo method and those found by the heuristic search methods. Conditions for the superiority of either method are identified. Therefore, the current study complements earlier studies by providing analytical arguments and additional experimental evidence for the effectiveness of simple Monte Carlo method and intelligent search heuristics on solving layout problems.

Numerical investigation on the underground thermal imbalance of ground-coupled heat pump operated in cooling-dominated district

Underground thermal imbalance is a common problem in ground-coupled heat pump (GCHP) system operated in cooling-dominated district, which will cause the average underground soil temperature to rise, and inevitably deteriorate the operation performance of GCHP system. In this paper, a two-dimensional heat transfer model with groundwater advection was developed for modeling the heat transfer of underground GHE array. The influences of underground thermal imbalance rate, soil type, borehole layout and groundwater advection on the underground soil temperature distribution were analyzed. The results indicate that the soil temperature increase with the increase of the ratio of annual heat released into the ground to that extracted from the ground, and thus the underground thermal imbalance becomes worse. The better the soil thermal conductivity and diffusivity are, the faster the soil heat diffusion is, and thus the underground heat buildup can be alleviated. At the same time, the underground thermal imbalance can be controlled or eliminated by decreasing the intensive degree of borehole layout through increasing the borehole spacing or using strip type and block layout. Additionally, the underground heat buildup can be efficiently removed by the groundwater advection.

On the block layout shortest loop design problem

This article verifies a formulation presented by Asef-Vaziri, Laporte, and Sriskandarajah (2000) for the block layout shortest loop design problem. An error in the set of connectivity constraints of the formulation is corrected and then it is shown that a new set of constraints is needed to guarantee that every solution satisfying the corrected formulation determines a complete loop; i.e., a loop covering each production cell of the block layout. Finally, a cutting-plane algorithm is developed to solve the corrected formulation. The proposed algorithm solves instances with sizes of up to 100 departments in less than 3 seconds. This shows that the algorithm outperforms the best algorithm proposed in the literature, which can solve instances with sizes of up to 80 in less than 60 seconds.

The concurrent block layout problem

The interdependency of block layout and detail level work centre layout is discussed and used to motivate the problem of concurrent block layout planning. The concurrent perspective emphasises the simultaneous minimisation of materials handling cost between work centres and maximisation of activity relationships within work centres. The resultant bi-criteria problem is formulated and a series of test problems are generated. Simple Monte Carlo simulation is used to demonstrate how modelling tools applied to the traditional block layout problem could be adapted in the development of a new class of algorithms based on the concurrent perspective.

Simulation study of an electrically read- and writable magnetic logic gate

In order to keep up with economic growth and competitiveness the performance of microelectronic components will continuously increase, thanks to the introduction of new device types and materials. Spin based technologies are promising candidates because of their fast switching capability, high endurance, and non-volatility. Furthermore, the use of spin as a degree of freedom permits the combination of information storage and processing in a single device creating a fully non-volatile information processing system and thus allowing an even denser layout of simplified building blocks. Recently a fully electrical read–write 1 bit demonstrator memory device out of a ferromagnetic semiconductor has been shown and it has been proposed to extend this device to a logic XOR gate. However, up to now neither the feasibility of this gate nor the extendability to further logic gates has been shown. In this work we carried out a rigorous simulation study of the proposed logic gate. We are able to show that firstly the magnetization can be switched diagonally. Secondly, by changing the relative angle between the current flow path and the magnetization, not only a XOR gate is feasible but also (N)AND and (N)OR gates can be realized.

A descriptive analysis of quantitative indices for multi-objective block layout

Layout generation methods provide alternative solutions whose feasibility and quality must be evaluated. Indices must be used to distinguish the feasible solutions (involving different criteria) obtained for block layout to identify s solution's suitability, according to set objectives. This paper provides an accurate and descriptive analysis of the geometric indices used in designing facility layout (during block layout phase). The indices studied here have advantages and disadvantages which should be considered by an analyst before attempting to resolve the facility layout problem. New equations are proposed for measuring geometric indices. The analysis revealed redundant indices and that a minimum number of indices covering overall quality criteria may be used when selecting alternative solutions.

Detailed Dynamic Layout Planning: An Adaptive Layout Approach

Layout planning deals with the arrangement of facilities in a plant. Layout planning is said to be dynamic when the problem deals with the design of multi period plan with changes in demand. This paper formulates the dynamic layout problem as a quadratic assignment problem. An adaptive approach is considered to solve the problem. Simulated annealing is proposed for the development of solution in the form of a block plan for the dynamic plant layout problem. Addition of details such as flow plans, aisle width, department input /output location, etc. to the block plan gives a new detailed layout called net aisle and department layout. An integer linear programming model is used for the formulation of this detailed layout. A LINGO program is developed to solve the model. Net aisle and department layout provide a more realistic layout than a block layout with a better estimation of material handling cost.

A 250°C ASIC Technology

Tekmos has developed a 250°C ASIC technology that uses the X-Fab XI10 SOI process. A gate array architecture was chosen to allow reduced mask costs and quicker manufacturing cycle times. The design of the technology includes first determining the optimum routing grid and then designing of the basic gate array transistors. The “A” style transistor was chosen over the “H” style to create stronger transistors. The choice of the transistor in turn sets the characteristics of the basic “Block” that is used in the gate array architecture. Another factor in the block design is the requirement for a pre-determined source with “A” transistors. This prevents the use of shared diffusions that are used in most gate array architectures and resulted in a different block layout. The pre-determined sources also required a change to the logic cell library. Since the basic transmission gate found in most flop designs cannot be used, alternative logic architectures were developed. By implementing the SOI specific library into the Tekmos standard logic library, the SOI peculiarities were masked from the end designer. The 250°C ASIC technology was demonstrated in a FPGA conversion, in which a design in an Actel MX series FPGA was reimplemented in the 250°C ASIC technology. A standard FPGA design conversion flow was used, and the only issues were related to the speed and voltage differences between the FPGA and the 1.0μ ASIC. These were addressed through critical path analysis and some slight circuit modifications. The temperature derating for 250°C was significant, but enough margin was retained to allow the circuit to work. Parts were made and worked as expected at 250°C. The life testing results at 280°C have been satisfactory. On an experimental basis, parts were evaluated at temperatures of up to 305°C without failure.

A Slicing Tree Representation and QCP-Model-Based Heuristic Algorithm for the Unequal-Area Block Facility Layout Problem

The facility layout problem is a typical combinational optimization problem. In this research, a slicing tree representation and a quadratically constrained program model are combined with harmony search to develop a heuristic method for solving the unequal-area block layout problem. Because of characteristics of slicing tree structure, we propose a regional structure of harmony memory to memorize facility layout solutions and two kinds of harmony improvisation to enhance global search ability of the proposed heuristic method. The proposed harmony search based heuristic is tested on 10 well-known unequal-area facility layout problems from the literature. The results are compared with the previously best-known solutions obtained by genetic algorithm, tabu search, and ant system as well as exact methods. For problems O7, O9, vC10Ra, M11*, and Nug12, new best solutions are found. For other problems, the proposed approach can find solutions that are very similar to previous best-known solutions.

Comparison of Heat Losses for Different Shapes and Size Volumes

The shape of a house significantly affects the amount of heat loss. Compact building, especially without various projections, has a smaller proportion of the cooled surface of the floor surface area and its volume. The ideal shape is a sphere, but in terms of practical use in the cube or block layout is preferable. For this purpose, were created on the same ground plan standards areas and various levels of the circuit. These demonstrate the amount of heat loss, depending on the shape of the object.

Block layout method in the block stockyard based on the genetic algorithm

Due to its large size, a ship is first divided into scores of blocks and then each block is constructed through various shops, such as the assembly shop, the painting shop, and the outfitting shop. However, each block may not be directly moved to the next shop and may be temporarily laid at a block stockyard because the working time in each shop is different from each other. If blocks are laid at the block stockyard without any planning, the rearrangement of the blocks by a transporter is required because the blocks have the different in and out time. In this study, a block layout method based on the genetic algorithm was proposed in order to minimize the rearrangement of the blocks in the block stockyard. To evaluate the applicability of the proposed method, it was applied to simple layout problems of the block stockyard. The result shows that the proposed method can yield a block layout that minimizes the total relocation cost of moving obstacle blocks in the block stockyard.

Biorregulador na composição química e na produtividade de grãos de soja

The objective of this study was to evaluate the chemical composition and yield of the soybean in response to the application of plant growth regulator to a soybean crop. For this purpose, seeds of the cultivar BRS 246 RR were sown in October of the agricultural years 2007/2008 and 2008/2009, in an experimental layout of complete blocks, with randomized treatments and four replications. The treatments, arranged in factorial design, consisted of the combination of seed treatments and plant growth regulator (with and without 0.5 L 100kg-1 of seeds) and five doses of the product (0, 0.125, 0.25, 0.375 and 0.5 L ha-1) applied to the leaves at two stages of the crop development (V5 or R3). A liquid growth regulator, Stimulate®, from Stoller of Brazil Ltda was used, consisting of three plant growth regulators in the following concentrations: 0.005% indolebutyric acid IBA - IBA (auxin analogue), 0.009% kinetin (cytokinin) and 0.005% gibberellic acid - GA3 (gibberellin). The use of plant growth regulator had an influence on the increase in productivity; oil and protein levels were altered by the action of the regulator, which tended to favour the protein content.

Effects of forest inventory errors on the area and spatial layout of harvest blocks

In modern forest inventory methods, inventory data can be interpreted for raster cells or small irregular spatial units called micro-segments, instead of conventional stand compartments. Adjacent raster cells or micro-segments need to be clustered into larger units for feasible forest management operations. This clustering can be achieved by spatial optimization. The optimization result is, however, affected by errors in the forest inventory data. This study investigated the effect of errors in inventory based on airborne laser scanning on the total area and spatial layout of harvest blocks created by spatial optimization. The results showed that the total harvest area was 12.5 % larger when erroneous data were used, compared to reference data. The increase in harvest area was explained by the averaging (Berkson type) errors of the inventory based on airborne laser scanning. Due to inventory errors, the spatial layout of harvest blocks differed by 19.0 % of the layout based on reference data. One possibility for avoiding overharvest and the difference in spatial layout is to harvest only those micro-segments where the probability of harvest prescription is high.

Usulan Tata Letak Ulang Menggunakan Software Quantitative Systems untuk Meminimalkan Jarak Perpindahan Bahan di Lantai Produksi Departemen Mechanic PT Jefta Prakarsa Pratama

The layout applied on the production floor of the Department of Mechanic of PT. Jefta Prakarsa Pratama is not considered as an optimal layout. The reason triggered this optimal level, are some backtrack movements that reduce the effectiveness and efficiency of material handling activities. This research refers to two types of calculation methods. First, manual calculation, which is rectilinear distance measure. Second, computerized calculation, which is Quantitative Systems (QS) software. There are three critical criterias referenced in this research, i.e. straight flow of material, more minimal backtrack movement, and more minimal material moving distance. The iteration results using QS software are translated into block layout and then are made as a proposed layout. The rectilinear calculations performed manually are intended to calculate the total of material moving distance. The data processing obtained a re-layout solution which is more optimal for the production floor of the Department of Mechanic, because it could reduce backtrack distance by 75.28% and the material moving distance by 30.03%. The implementation of the proposed layout is expected to reduce the time of material moving activity on the production floor of the Department of Mechanic, so that the material moving process could run more effectively and efficiently.

Retail space design considering revenue and adjacencies using a racetrack aisle network

In this article, a model and solution approach for the design of the block layout of a single-story department store is presented. The approach consists of placing departments in a racetrack configuration within the store subject to area and shape constraints. The objective function considers the area allocated to each department, contiguity of the departments to the aisle network, adjacency requirements among departments, and department revenues. The revenue generated by a department is defined as a function of its area and its exposure to the aisle network. The aisle network is comprised of two components: the racetrack, which serves as the main travel path for the customers, and the entry/exit aisle. The racetrack aisle itself is treated as a department with area allocation and corresponding revenue generation. A general tabu search optimization framework for the model with variable department areas and an aisle network with non-zero area is devised and tested.

Block spatial scheduling modelling and application in shipbuilding

With the wide application of module-shipbuilding technology, problems related to block spatial scheduling occur in various working areas, and this restricts the productivity of shipbuilding. To address the problems and to obtain the optimum block sequence and spatial layout, typical block features and work plates were investigated. A heuristic spatial scheduling model was established based on the investigation and proposed strategies with the objective to minimise makespan. With the heuristic algorithm, a block spatial scheduling system was developed and implemented with real data from a large ship. Through the spatial scheduling system, visual results of daily block layouts and progress charts for all blocks can be easily obtained and work orders can also be created for site workers. Several other spatial scheduling methods are described and compared with the above-mentioned heuristic algorithm. The result shows that the heuristic algorithm is better than Cplex and a genetic algorithm in solving large-scale block scheduling, and the heuristic algorithm is better than a grid algorithm and manual scheduling in all aspects such as makespan, utilisation of work plates, runtime of scheduling and on-time delivery. The developed block spatial scheduling system is applied in a block production shop of a modern shipyard and shows good performance.