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1.
Facility layout design has an important effect on the performance of manufacturing systems. It intends to determine relative location of departments and machines within a plant. A good layout design must ensure that a set of criteria and objectives are met and optimised, e.g. area requirements, cost, communication and safety. The most common objective used in facility planning methods is to minimise the transportation cost. However, factors such as the plant safety, flexibility for future design changes, noise and aesthetics must be considered as well. In this paper, a case study is carried out to investigate the safety concerns in facility layout design. In this regard, a facility layout planning methodology, integrating occupational health and safety (OHS) is presented. This methodology considers transportation cost as well as safety in the facility design. By this means, OHS issues are considered at the design stage of the facility. In other words, this research demonstrates the improvements in the layout design by integrating safety aspects.  相似文献   

2.
This paper presents an integrated approach for the facilities design problem. It develops a method for the concurrent determination of the block layout, the locations of departmental input and output (I/O) points using the contour distances between the I/O points, and the material flow paths between the I/O points. The topology of block layouts is represented using two linear sequences (sequence-pair), which allows the layout to have either a slicing or a non-slicing structure. The block layout is obtained from the sequence-pair with a linear programming formulation. Three heuristic methods are then presented to determine for a given block layout the locations of the I/O points on the perimeters of the departments. The flow paths from output to input points are found by determining the shortest paths that follow the perimeters of the departments. The linear programming algorithm, the shortest path algorithm, and the I/O point location heuristics are embedded into a simulated annealing algorithm that modifies the sequence-pair to obtain a high-quality layout based on the contour distances between the I/O points. Results of computational experiments show that the performance of this integrated algorithm compares favourably with those of algorithms using a sequential approach and is capable of solving industrial-sized problems in acceptable computation time.  相似文献   

3.
Simultaneous planning of project scheduling and material procurement can improve the project execution costs. Hence, the issue has been addressed here by a mixed-integer programming model. The proposed model facilitates the procurement decisions by accounting for a number of suppliers offering a distinctive discount formula from which to purchase the required materials. It is aimed at developing schedules with the best net present value regarding the obtained benefit and costs of the project execution. A genetic algorithm is applied to deal with the problem, in addition to a modified version equipped with a variable neighbourhood search. The underlying factors of the solution methods are calibrated by the Taguchi method to obtain robust solutions. The performance of the aforementioned methods is compared for different problem sizes, in which the utilized local search proved efficient. Finally, a sensitivity analysis is carried out to check the effect of inflation on the objective function value.  相似文献   

4.
The numerical modeling of dynamic failure mechanisms in solids due to fracture based on sharp crack discontinuities suffers in situations with complex crack topologies and demands the formulation of additional branching criteria. This drawback can be overcome by a diffusive crack modeling, which is based on the introduction of a crack phase field. Following our recent works on quasi‐static modeling of phase‐field‐type brittle fracture, we propose in this paper a computational framework for diffusive fracture for dynamic problems that allows the simulation of complex evolving crack topologies. It is based on the introduction of a local history field that contains a maximum reference energy obtained in the deformation history, which may be considered as a measure of the maximum tensile strain in the history. This local variable drives the evolution of the crack phase field. Its introduction provides a very transparent representation of the balance equation that governs the diffusive crack topology. In particular, it allows for the construction of a very robust algorithmic treatment for elastodynamic problems of diffusive fracture. Here, we extend the recently proposed operator split scheme from quasi‐static to dynamic problems. In a typical time step, it successively updates the history field, the crack phase field, and finally the displacement field. We demonstrate the performance of the phase field formulation of fracture by means of representative numerical examples, which show the evolution of complex crack patterns under dynamic loading. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

5.
Unidirectional loop layouts (ULLs) are the preferred layouts in manufacturing systems owing to their relative low investment costs, high material handling elasticity and routing flexibility. Existing formulations of the unidirectional loop layout problem are concentrated on the arrangement of workstations under the assumption that the number and location of loading and unloading stations are known. In this study, the unidirectional loop layout problem is generalised by consideration of potentially attachable loading/unloading equipment to each workstation and releasing of the predetermined number of loading and unloading stations. Thus, more efficient and effective loop layout designs are allowed by eliminating some artificial restrictions. The present ULL model is generalised and a genetic algorithm is developed to solve the problem. Solutions obtained by the genetic algorithm outperformed those obtained by conventional methods. Additionally, comparisons of the generalised model with existing models on randomly generated test problems yielded encouraging results.  相似文献   

6.
Background: The present study is to investigate the neuroprotective effect of ibuprofen by intranasal administration of mucoadhesive microemulsion (MMEI) against inflammation-mediated by dopaminergic neurodegeneration in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of Parkinson’s disease (PD).

Methods: Ibuprofen-loaded polycarbophil-based MMEI was developed by using response surface methodology (RSM). Ibuprofen with dose of 2.86 mg/kg/day was administered intranasally to male C57BL/6 mice for two consecutive weeks which were pre-treated with four intraperitoneal injections of MPTP (20?mg/kg of body weight) at 2?h intervals. Immunohistochemistry was performed.

Results: Optimal MMEI was stable and non-ciliotoxic with 66.29?±?4.15?nm as average globule size and??20.9?±?3.98?mV as zeta potential. PDI value and transmission electron microscopy result showed the narrow globule size distribution of MMEI. The result showed that all three independent variables had a significant effect (p?<?0.05) on the responses. Rota-rod and open-field test findings revealed the significant improvement in motor performance and gross behavioral activity of the mice. The results from in vivo study and immunohistochemistry showed that nasal administration of Ibuprofen significantly reduced the MPTP-mediated dopamine depletion. Furthermore TH neurons count in the substantia nigra and the density of striatal dopaminergic nerve terminals were found to be significant higher for ibuprofen treated groups.

Conclusion: Findings of the investigation revealed that Ibuprofen through developed MMEI was shown to protect neurons against MPTP-induced injury in the Substantia nigra pars compacta (SNpc) and striatum and hence, could be a promising approach for brain targeting of Ibuprofen through intranasal route to treat PD.  相似文献   

7.
Robust design (RD) techniques, which are based on the concept of building quality into products or processes, are increasingly popular in industry primarily because of their practicality. Traditional RD principles have often been applied to situations in which the quality characteristics of interest are time‐insensitive. However, when time‐oriented quality characteristics are studied, censored data often occur. As a result, current RD models reported in the literature may not be effective in finding solutions based on such data. To address such practical needs, this paper develops a censored RD model. We also propose an estimation method that is closely related to the expectation–maximization algorithm and compare it with the method of maximum likelihood estimation via a numerical example. Model validation is conducted, and comparative studies are discussed for model verification. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

8.
Scientometrics - Strategies employing information science and scientometric approaches were introduced to science policy and management over the past decades. As a rapidly evolving field, new...  相似文献   

9.
Scientometrics - On the basis of the Impact Factor of Journal Citation Reports developed by ISI as a journal quality indicator, this paper puts forth an ordinal regression model to estimate the...  相似文献   

10.
A computational method for the design of directional alloy solidification processes is addressed such that a desired growth velocity νf under stable growth conditions is achieved. An externally imposed magnetic field is introduced to facilitate the design process and to reduce macrosegregation by the damping of melt flow. The design problem is posed as a functional optimization problem. The unknowns of the design problem are the thermal boundary conditions. The cost functional is taken as the square of the L2 norm of an expression representing the deviation of the freezing interface thermal conditions from the conditions corresponding to local thermodynamic equilibrium. The adjoint method for the inverse design of continuum processes is adopted in this work. A continuum adjoint system is derived to calculate the adjoint temperature, concentration, velocity and electric potential fields such that the gradient of the L2 cost functional can be expressed analytically. The cost functional minimization process is realized by the conjugate gradient method via the FE solutions of the continuum direct, sensitivity and adjoint problems. The developed formulation is demonstrated with an example of designing the boundary thermal fluxes for the directional growth of a germanium melt with dopant impurities in the presence of an externally applied magnetic field. The design is shown to achieve a stable interface growth at a prescribed desired growth rate. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

11.
ABSTRACT

The objective of this paper is to analyze a tiering scoping approach developed to identify critical multidimensional sustainability issues and impacts of a large infrastructure project: the land transport project linking northern Brazil with a new port on Guyana’s coast. The Inter-American Development Bank awarded a technical assignment to develop the terms of reference of a country environmental assessment, a strategic environmental and social assessment and an environmental and social impact assessment of the project(s). The complexity of the issues at stake lead to the design of a tiered assessment process supported by wide-ranging participative sessions involving 170 individuals from Guyana and Brazil and from diverse sectors. The process identified ex ante conditionalities, critical factors for decision-making and valued socioenvironmental and governance components. Such complex and determinant planning initiatives for the future of a country need to be supported by comprehensive, well-sequenced scoping processes.  相似文献   

12.
旨在探讨清末民国时期中国书刊设计对智能时代字体创新的影响,侧重于传统脉络的延续与创新的融合。通过分析清末民国时期书刊设计的中西杂糅特点,厘清中国传统印刷业脉络,揭示其对当代文字设计的启发,并将其投射至新情境、新业态、新媒介中。首先,考察清末民国时期书刊设计的变革,包括版面转型、铅印技术的普及与文化观念的转变,以及其对当时社会文化生活的深远影响;其次,分析智能时代文字设计的演变,探讨复古与创新之间的平衡,以及传统脉络在当代字体排印设计中的体现。清末民国时期书刊设计的多元共存与中西杂糅为智能时代字体创新提供了重要启示。传统的书刊设计不仅是文化的传承,更是当代文字设计的灵感源泉。对传统脉络的重新审视和当代技术的结合,将推动文字设计在智能时代的发展,实现传统与现代的有机融合。  相似文献   

13.
14.
The design of experiments (DoE) methodology is a technique that has been applied for many years in industry to improve quality. In this study, a summary of 77 cases of practical DoE application in the field of engineering is presented. All of the cases were published in important scientific journals between 2001 and 2005. The type of design that is applied, the size of the experiment, the number of factors that influence the response variable, and the sector of application of the design are analyzed. In addition, the increasing use of these designs over time is demonstrated. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

15.
This paper is an analysis of how cultural heritage values are handled in documentation related to early phase evaluations of major public investment projects in Norway. This study was instigated by an apparent lack in the consideration of cultural heritage values in such documentation. We conducted a case study document analysis to see how cultural heritage issues are addressed in the early phases of projects. Methodologically, the paper analyses the use of vocabulary related to cultural heritage values in the documentation. There is uniform documentation available from these projects. The results suggest that cultural heritage values are mentioned but seldom substantially discussed in the documents. Cultural heritage values tend to be discussed using non-specific language. There is an emphasis on legislation regarding cultural heritage and how the legislation can be a problem. Today’s discussion of cultural heritage values appears to be lacking and in need of a strengthened framework. The methodology applied in this study aims to provide a structured search method for the unstructured discussion of cultural heritage issues in these extensive documents.  相似文献   

16.
Getting the right people in the right place at the right time has always been a major organizational challenge. In ancient times this process seems to have been accomplished based on the scheme of arrangements being contained in the leader’s mind and instructions communicated verbally. Modern approaches to solving the twin challenges of first thinking through the ‘plan’ and then communicating the plan to the people who need to do ‘the right work, at the right time, in the right place’ use sophisticated graphics, charts, diagrams, and computations. This paper traces the development of the concepts most project managers take for granted including bar charts and critical path schedules from their origins (which are far earlier than most people think) through to the modern day. The first section of the paper looks at the development of concepts that allow the visualization of time and other data. The second looks at the shift from static representations to dynamic modeling through the emergence of computers, dynamic calculations and integrated data from the 1950s to the present time.  相似文献   

17.
To date, the main focus of intelligent transport systems (ITS) research programmes has been on technology development and proof of concept, rather than on understanding the implications of system implementation. Improved knowledge is needed about the ways in which drivers use ITS, their short- and long-term effects and how system performance can be optimised. The field operational test, or FOT, is a sophisticated evaluation method that can be used to answer these and other critical questions, and to stimulate market acceptance and demand for ITS. Although the large-scale FOTs conducted to date have yielded important insights into both the positive and potentially negative impacts of ITS, there is considerable scope for improving the design and implementation of FOTs. There are many advantages in doing so. The authors outline, in the form of a checklist, the critical steps and considerations involved in successfully planning and implementing an FOT, drawing on work undertaken in the EC-funded FESTA (Field opErational TeSt support Action) project.  相似文献   

18.
Governments at all levels are increasingly motivating the private sector to participate in infrastructure development using alternative project delivery methods to relieve financial burden. When designing contracts, governments usually offer incentives while requiring cost or time guarantee to balance project attractiveness to the private sector and fair protection of public interest. However, a practical and critical problem is how to properly design these provisions. Although previous studies have investigated the value of these provisions, a knowledge gap still exists with respect to methods of fairly and effectively designing such provisions. This study fills this gap by developing a methodology that analyzes the appropriateness of guarantee or warranty provisions for contracts. In this study, a contract reliability index is constructed, and a process of evaluating contract reliability is proposed. The New Mexico Highway 44 project, in which three warranty provision arrangements are investigated, is used as a case study to illustrate the analysis process. Results show that although a ceiling clause can effectively motivate the private sector to participate in the project, it sacrifices a significant amount of public benefits. By contrast, although a warranty option can protect public benefits, it cannot effectively incentivize the private sector. A combination of the ceiling clause and the warranty option will therefore result in improved contract provision design. The proposed methodology in this study is especially useful for governments in properly determining contract clauses in infrastructure development.  相似文献   

19.
A renewed methodology for simulating two-spatial dimensional stochastic wind field is addressed in the present study. First, the concept of cross wavenumber spectral density (WSD) function is defined on the basis of power spectral density (PSD) function and spatial coherence function to characterize the spatial variability of the stochastic wind field in the two-spatial dimensions. Then, the hybrid approach of spectral representation and wavenumber spectral representation and that of proper orthogonal decomposition and wavenumber spectral representation are respectively derived from the Cholesky decomposition and eigen decomposition of the constructed WSD matrices. Immediately following that, the uniform hybrid expression of spectral decomposition and wavenumber spectral representation is obtained, which integrates the advantages of both the discrete and continuous methods of one-spatial dimensional stochastic field, allowing for reflecting the spatial characteristics of large-scale structures. Moreover, the dimension reduction model for two-spatial dimensional stochastic wind field is established via adopting random functions correlating the high-dimensional orthogonal random variables with merely 3 elementary random variables, such that this explicitly describes the probability information of stochastic wind field in probability density level. Finally, the numerical investigations of the two-spatial dimensional stochastic wind fields respectively acting on a long-span suspension bridge and a super high-rise building are implemented embedded in the FFT algorithm. The validity and engineering applicability of the proposed method are thus fully verified, providing a potentially effective approach for refined wind-resistance dynamic reliability analysis of large-scale complex engineering structures.  相似文献   

20.
Six different formulations of wood–plastic composites (WPC) fabricated from wood and polypropylene (PP) were tested in the laboratory against decay and termites and in a protected above-ground field test in southern Japan. Variables examined included comparisons of untreated and zinc borate (ZnB) incorporated formulations, wood content ratio, wood particle size and increased surface area via surface grooves (channels) to promote moisture infusion. A standard method originally designed to test durability of solid wood was modified for testing WPC. Wood decay fungi and Formosan subterranean termite activity in laboratory and field tests resulted in different mass losses, post-decay moisture contents and field test ratings depending on their wood and ZnB content. The results show that as wood content increased, mass losses also increased. Addition of ZnB at 1% (w/w) retention level significantly decreased mass losses of wood–plastic composite when exposed to laboratory decay and termite tests. The effects of surface grooves and wood particle size were less important, compared to wood particle content. All WPC tested were highly resistant to fungal decay under protected above-ground field conditions during 36 months. Termite attack, on the other hand, started at earlier stage reducing mean ratings 1 year after the installation.  相似文献   

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