Mitigation of risk in facility layout design for single and multi-period problems

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%.     

A simulated annealing algorithm based on a closed loop layout for facility layout design in flexible manufacturing systems

Facility layout design problems in flexible manufacturing systems (FMS) differ from traditional facility design problems and are more difficult to solve because there are more constraints that must be considered (i.e., cell shape, cell orientation, pick-up and drop-off point positions). The focus of this paper is on the closed loop type layout, which is based on a predetermined layout pattern. This layout pattern is commonly found in manufacturing settings since it requires a simplified material handling system configuration and since it facilitates a modular and expandable layout structure. The open-field type layout problem, where there is no predetermined layout pattern, may potentially have a more efficient configuration, since there are fewer restrictions. However, this problem is more difficult to solve and may result in configurations that are not desirable due to the lack of structure or modularity. The procedure developed in this paper improves the efficiency of the closed loop configuration by changing the rectangular shape of the loop to different sizes. In many cases, the resulting closed loop layout proves to be as efficient as the open field layout. A simulated annealing procedure (SA-CL) is used to search for the configuration that minimizes the total material handling costs. A comparison of the results with existing methods indicates that, based on solution quality and computational time, the SA-CL offers a favourable alternative for efficient layout design.     

Using queuing theory and simulated annealing to design the facility layout in an AGV-based modular manufacturing system

An automated guided vehicle-based flow production system is used for manufacturing prefabricated bathroom units. One unit can occupy a space of more than 10?m². Due to large time deviations in sequential processes, queues are formed and greater plant space is needed. Reducing work-in-progress helps to save plant space but renders manufacture less efficient. The research explores better workstation arrangements. An open queuing network (OQN) model was used to approximate the flow production system. Since the problem of workstation arrangement is a combinatorial optimisation problem, simulated annealing (SA) was applied to search for a good solution. The combination of an OQN model and SA provides a powerful tool to solve the facility layout problem for a stochastic flow production system. The experimental results show that the proposed approach has the potential to guide industrial layout design and practice.     

Optimisation of facility layout design problem with safety and environmental factors by stochastic DEA and simulation approach

This article presents an integrated computer simulation–stochastic data envelopment analysis (SDEA) approach to deal with the job shop facility layout design problem (JSFLD) with stochastic outputs and safety and environmental factors. Stochastic outputs are defined as non-crisp operational and deterministic inputs. At first, feasible layout alternatives are generated under expert decision. Then, computer simulation network is used for performance modelling of each layout design. The outputs of simulation are average time-in-system, average queue length and average machine utilisation. Finally, SDEA is used with Lingo software for finding the optimum layout alternative amongst all feasible generated alternatives with respect to stochastic, safety and environmental indicators. The integrated approach of this study was more precise and efficient than previous studies with the stated outputs. The results have been verified and validated by principal component analysis. The unique features of this study are the ability of dealing with multiple inputs (including safety) and stochastic (including environmental) outputs. It also uses mathematical programming for optimum layout alternatives. Moreover, it is a practical tool and may be applied in real cases by considering safety and environmental aspects of the manufacturing process within JSFLD problems.     

Combination of Lean value-oriented conception and facility layout design for even more significant efficiency improvement and cost reduction

Global market competition and fluctuating customers’ demands require manufacturing enterprises to focus on cost reduction and efficiency improvement to increase competitiveness and sustainability. The purpose of the research was the elaboration of the methodology and procedure of a new combined efficiency improvement method which basically applies Lean methods and also uses the facility layout design (FLD) method simultaneously, integrating the different advantages of these methods, which is even more efficient that applying each of the methods individually. The main significant added-value of the study is the elaboration of a new combined method, which results in even more significant improvement of efficiency and several KPIs, furthermore, cost reduction, which is confirmed by a real case study for the improvement of a manufacturing plant. In the case study, the application of 13 Lean methods and the FLD method (which aims at the minimisation of material workflow, travel distance of materials, material handling cost and space used for assembly) led to the improvement of 10 quantitative and 5 qualitative indicators: productivity; cycle-time; number of workstations and operators; WIP (work-in-process) inventories; space used for assembly; material workflow; travel distance of materials; material handling cost; labour cost; component supply; products’ quality; transparency; standardisation; workplace ergonomics.     

Layout design in fractal organizations

Today's complex, unpredictable and unstable marketplace requires flexible manufacturing systems capable of cost-effective high variety–low volume production in frequently changing product demand and mix. In fractal organizations, system flexibility and responsiveness are achieved by allocating all manufacturing resources into multifunctional cells that are capable of processing a wide variety of products. In this paper, various fractal cell configuration methods for different system design objectives and constraints are proposed. These parameters determine the level of interaction between the cells, the distribution of different product types among the cells and the similarity of cell capabilities. A tabu-search-based method is proposed to optimize the product distribution to the cells and the arrangement of machines and cells on the shop floor. This optimization is performed for different fractal cell configuration methods and cell quantities. The quality of the resulting shop floor layouts is measured in terms of resource requirements and material movements. The results indicate that in fractal layouts, a trade-off is required between machine quantities and material travelling distance. It was generally possible to reduce travelling distances by increasing the degree of optimization on machine layout and product distribution for a specific product demand and mix.     

Integration of occupational health and safety in the facility layout planning,part II: design of the kitchen of a hospital

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.     

Integrating occupational health and safety in facility layout planning,part I: methodology

An influential factor affecting the efficiency of a manufacturing facility is its layout. In a production facility, measure for efficiency can be based on the total cost of transporting the items between different departments and throughout the facility. However, other factors may influence efficiency of the manufacturing facility too. As such are: supporting the organisation's vision through improved material handling, material flow and control; effectively assigning people, equipment, space and energy; minimising capital investment; adaptability and ease of maintenance; as well as providing for employee safety and job satisfaction. By incorporating health and safety measures in the initial design of a facility layout, the organisation may avoid money and manpower loss resulting from industrial accidents. This paper proposes a facility layout planning methodology which integrates the occupational health and safety (OHS) features in the early design of a facility layout. The model considers transportation cost in the facility as well as safety concerns. By this means, the OHS issues are reflected prior to the construction of a facility.     

CO_2制冷剂在食品冷冻冷藏中的应用前景

CO2制冷剂在制冷与空调中的应用主要有三方面：热泵热水器、汽车空调和食品冷冻冷藏。本文论述了CO2制冷剂在食品冷冻冷藏中的应用前景。在国外超市已取得了成功的经验,由于我国正在加速R22的淘汰进程,相信在不久的将来会在我国超市中出现。     

Analysing risk in sourcing design and manufacture of components and sub-systems to emerging markets

This paper presents an emerging market sourcing risk assessment and management model for sourcing components and sub-systems to emerging markets. The model was developed, tested and implemented by a US automotive manufacturer but the principles and tool discussed here are broadly applicable. We gathered a comprehensive list of risk factors through an intensive literature review and subject matter expert (SME) interviews. We used a process failure mode effect analysis (PFMEA) structure to characterize the risks and developed a simulation model to quantify risk factors in terms of dollars so that an OEM can evaluate risk mitigation strategies. The spreadsheet simulation ranks causes of failures and failure modes and calculates total risk in terms of dollars. In addition to analysing risk, the model evaluates the impact of different inventory levels on the costs of delays in the supply chain. The model can also be used to evaluate and select suppliers that offer minimum risk. We demonstrate the model with a real-world case study involving a North American auto company considering sourcing a component to an emerging market.     

Nanotechnologies in Food Science:Applications,Recent Trends,and Future Perspectives

Nanotechnology is a key advanced technology enabling contribution,development,and sustainable impact on food,medicine,and agriculture sectors.Nanomaterials have potential to lead qualitative and quantitative production of healthier,safer,and high-quality functional foods which are perishable or semi-perishable in nature.Nanotechnologies are superior than conventional food processing technologies with increased shelf life of food products,preventing contamination,and production of enhanced food quality.This comprehensive review on nanotechnologies for functional food development describes the current trends and future perspectives of advanced nanomaterials in food sector considering processing,packaging,security,and storage.Applications of nanotechnologies enhance the food bioavailability,taste,texture,and consistency,achieved through modification of particle size,possible cluster formation,and surface charge of food nanomaterials.In addition,the nanodelivery-mediated nutraceuticals,synergistic action of nanomaterials in food protection,and the application of nanosensors in smart food packaging for monitoring the quality of the stored foods and the common methods employed for assessing the impact of nanomaterials in biological systems are also discussed.     

Scientific,statistical, practical,and regulatory considerations in design space development

The quality by design (QbD) paradigm guides the pharmaceutical industry towards improved understanding of products and processes, and at the same time facilitates a high degree of manufacturing and regulatory flexibility throughout the establishment of the design space. This review article presents scientific, statistical and regulatory considerations in design space development. All key development milestones, starting with planning, selection of factors, experimental execution, data analysis, model development and assessment, verification, and validation, and ending with design space submission, are presented and discussed. The focus is especially on frequently ignored topics, like management of factors and CQAs that will not be included in experimental design, evaluation of risk of failure on design space edges, or modeling scale-up strategy. Moreover, development of a design space that is independent of manufacturing scale is proposed as the preferred approach.     

空调室内机贯流风扇流动噪音的仿真研究

空调室内机空气流动噪音是影响室内舒适性的重要因素,为此对室内机贯流风扇的非定常流场及噪音特性进行了数值分析。采用非均匀滑移网格和RNG k-ε湍流模型对不可压缩流体非定常流动的Navier-Stokes方程进行求解,并采用Ffowcs-Williams and Hawkings模型对空气流场和噪音进行关联,对空调室内机内空气非定常流场及流动噪音进行数值分析,并与实验结果进行比较。结果表明,采用此方法对计算的流动噪音的声音品质和声谱特性都与测量结果有较好的吻合,为空调器空气流场的优化设计和降低空调器风扇及空气流动噪音的研究提供了有效工具。     

浅谈某生鲜加工配送中心设计施工的得与失

以某生鲜加工配送中心制冷工程设计施工为实例,介绍了主要冷区的设计特点,施工运行中所发现的如苯板锈蚀、夹层凝露等问题和解决措施,以及在设备配置与热回收系统设计中的得与失。以期为以后类似工程的设计施工提供参考。     

Cast metal matrix composites—challenges in processing and design

Development of metal matrix composites has extended the choice of materials particularly for the space, aero-space and automobile industries, with a view to reduce fuel consumption and operating cost by weight saving. Tailoring of a composite to suit a given application requires choice of constituents and promotion of desirable interfaces. Solidifcation processing of composites demands particular attention to wetting of dispersoids by alloys, defects like porosities and evolution of microstructures particularly in respect of changing the nature of interfaces in a composite.     

A hybrid approach for concurrent layout design of cells and their flow paths in a tree configuration

The layout design of multiple-cell automated manufacturing systems includes cell layout design and flow path layout design. Traditional layout methods often treat these two as separate problems and the sequence for solving them is usually cell layout first and flow path layout later. However, approaches of these kinds have one major drawback, that is, they may produce cell layouts that are awkward or difficult for designers to conduct flow path layouts, or cell layouts that do not turn out to be as good as expected after flow path layouts have been performed. Other drawbacks of traditional layout methods include irregular shapes of cells, inaccurate calculations of flow distances, etc. This paper addresses the layout problem of cells and their connecting flow paths in a tree configuration. The proposed layout procedure is designed to avoid the aforementioned drawbacks of traditional layout methods by emphasizing concurrent layout design of cells and flow paths. It combines a search algorithm and mathematical programming models. The search algorithm has a backtracking procedure that allows one to explore alternative layouts, while the mathematical programming models help one obtain accurate layouts of cells and flow paths. The proposed layout procedure also interacts with designers and allows designers to include their qualitative consideration into the layout design. As a result, one can obtain more accurate and good-quality layouts with the proposed layout procedure.     

空气处理机对高大空间流动形态影响的研究

为研究空气处理机对高大空间空气流动的影响,采用CFD软件对处理机进行仿真。对空间内流动矢量进行研究,得到了空间内的流速和流向的分布状态;经过对空间内温度云图的研究,得到了空间内的温度分布情况;统计处理机在不同安装高度条件下各分层的温度,得到了处理机不同安装高度对空间温度分布的影响。     

Development in high-grade dual phase steels with low C and Si design

Cold rolled dual phase steels with low C and Si addition were investigated in terms of combination of composition and processing in order to improve mechanical properties and workability including welding and galvanizing. Mo and Cr could be used as alloying elements to partially replace C and Si to assure enough hardening ability of the steels and also give solute-hardening. Mo addition is more effective than Cr addition in terms of obtaining the required volume fraction of martensite and mechanical strength. The ferrite grain was effectively refined by addition of Nb microalloying, which gives optimized mechanical properties. The experimental results show that it is possible to obtain the required mechanical properties of high grade 800 MPa dual phase steel, i.e., tensile strength>780 MPa, elongation>15%, and yield/tensile strength ratio<0.6 in the condition of low carbon (C<0.11 wt.%) and low silicon design (Si<0.05 wt.%) through adequate combination of composition and processing.     

Numerical simulation of the high strain-rate behavior of quenched and self-tempered reinforcing steel in tension

This paper presents the numerical analysis of the high strain-rate behavior of quenched and self-tempered reinforcing steel in tension. The investigation has been performed properly simulating the experimental facility (SHTB-Split Hopkinson Tension Bar), highlighting criticism in the simulation and interpretation of the experimental results. Finite element simulation has allowed a robust model validation of the B450C reinforcing steel. Parametrical finite element model has been used to rebuild the input and output signals of the SHTB. Physical influence of damping in input wave and modeling strategies have been discussed. The elastic and damping dispersion fonts have been introduced into the model to explain the real case variability in SHTB signals. Strain-rate dependent plasticity model has been used by LsDyna code features. Time dependent plasticity has been developed to explain upper and lower yield values of the material resulting into a loading rate sensitivity. Finally, the material model has been used to reconstruct a virtual test over a rebar of 32 mm diameter, as an example of general procedure to calculate the global material response.