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This study is divided into two parts. The first study determines window size and size reductions for different wall and ceiling reflectance combinations that are needed in a classroom to achieve one leadership in energy and enviro...
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This study is divided into two parts. The first study determines window size and size reductions for different wall and ceiling reflectance combinations that are needed in a classroom to achieve one leadership in energy and environmental design (LEED) daylight factor credit. The second study determines the power consumption of indirect luminaires with a target illuminance of 538 lux for different wall and ceiling reflectance combinations. LEED credits for the optimizing energy performance are determined. It is found that ceiling reflectance has a higher impact on light levels and energy performance than wall reflectance. A ceiling reflectance of 90% and wall reflectance of 75% allows a minimum window-to-wall ratio of 0.444 to achieve one LEED daylight factor credit. The same room decreases lighting power density for an indirect fluorescent lighting system by one-third below the maximum permissible lighting power density specified in American Society of Heating, Refrigerating and Air-Conditioning Engineers/Illuminating Engineering Society of North America (ASHRAE/IESNA) Standard 90.1-2001. If lighting constitutes 50% of the total ASHRAE/IESNA 90.1 load, 0.92 LEED credits for the optimization of energy performance can be obtained for new construction and 2.92 credits can be obtained for existing buildings.
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To evaluate the dynamic behaviours of bridges, many researchers have analysed interactions between vehicles and bridges with numerical methods instead of field loading tests. However, conventional numerical methods take too much t...
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To evaluate the dynamic behaviours of bridges, many researchers have analysed interactions between vehicles and bridges with numerical methods instead of field loading tests. However, conventional numerical methods take too much time and cost to evaluate the impact factor of bridges in design and maintenance practice. The objective of this study was to propose improved design criteria by using impact factors based on natural frequency rather than span length of railway bridges using dynamic field load-carrying capacity test database. The improved design criteria use a different methodology than that outlined in the International Union of Railway specifications Code. Statistical regressions are applied to more easily estimate the natural frequency of a bridge with a span length of 20 m or longer with steel plate girder or truss superstructures. Calculated impact factors were compared to impact factors obtained from field measurements. Results indicated that the improved method could provide a very reliable estimation for actual impact factors. Since the suggested impact factor criteria are conservative, the proposed method can be used in design and management stages to consider dynamic effects of railway bridges in a more intuitive manner.
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This paper presents a spreadsheet-based decision support system (DSS) for any parameter optimization problem, in the small- and medium-sized enterprises to help the managers to make better decisions. Microsoft Excel is used as a D...
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This paper presents a spreadsheet-based decision support system (DSS) for any parameter optimization problem, in the small- and medium-sized enterprises to help the managers to make better decisions. Microsoft Excel is used as a DSS development platform. The DSS application requires the quality characteristics and the level of parameters affecting the problem. The proposed system considers three multi-criteria decision-making methods: TOPSIS, VIKOR and GRA. These methods are integrated into the Taguchi method to convert the multi-response optimization problem to a single-response problem. The DSS suggests proper Taguchi experimental designs and provides the decision maker with an opportunity to use different metrics and to validate the experimental results. Several issues and an application are provided for illustrative purposes. The proposed DSS is tested on a case study (the performance of the mixed integer programming (MIP) formulation solver) and the results highlight that the system is capable of offering satisfactory outcomes. Using such a quick and flexible DSS might help to reduce the daily workload of the decision makers. The different metrics used for the response variables which results with the different parameter combination. Using the optimal parameter combination of TOPSIS (come to the fore in case MinBest metric used), the MIP formulation solver gives the best integer objective function value of 609 and a GAP value of 1.93%, both of which are less than the values obtained using the other methods. Using the optimal parameter combination of GRA (come to the fore in case OptBest metric used), the MIP formulation gives a best integer objective function value of 632 and a GAP value of 6.52%, both of which are less than the values obtained by using the other methods.
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Process assessment enables one to identify strengths and weaknesses of selected processes in a specific domain typically by referencing process maturity/capability frameworks. Assessment findings are usually transformed into actio...
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Process assessment enables one to identify strengths and weaknesses of selected processes in a specific domain typically by referencing process maturity/capability frameworks. Assessment findings are usually transformed into action items for process improvement. In the healthcare domain where hospitals offer high-risk services to patients every day in a complex, dynamic, and multidisciplinary environment, establishing process thinking and effective process management is increasingly demanded but not an easy task to accomplish. In this study, the authors investigate the maturity/ capability frameworks that are proposed or used for assessing and improving the healthcare processes. They searched the studies reported between the years 2000 and 2015 in scientific digital libraries and identified 29 studies out of 958 initially retrieved in a systematic way. They reviewed six studies out of 29 with respect to a number of research questions and compared them against design criteria that the authors elicited from related studies in literature. The results of review and comparison indicate that: 1) there is a need for proposing and using maturity/capability frameworks as specific to healthcare; 2) the use of maturity/capability frameworks for specific contexts in healthcare might bring significant benefits; and 3) the majority of the frameworks newly proposed in healthcare settings are lacking basic, descriptive, or prescriptive design properties. The authors hope their findings will be useful in managing new developments and adaptations of maturity/capability frameworks in the healthcare domain.
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The selection of the most appropriate material, or combination of materials, is a demanding intellectual process that takes a lot of time and experience. There are a large number of established and newly developed materials, and t...
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The selection of the most appropriate material, or combination of materials, is a demanding intellectual process that takes a lot of time and experience. There are a large number of established and newly developed materials, and their associated materials processes, necessitating the simultaneous consideration of many conflicting criteria. This has highlighted the importance of the developing field of multi-criteria decision-making (MCDM) to the material selection process which is especially useful for high technology market where product differentiation and competitive advantage are often achievable with just small gains in material performance. It is clear that decision-making techniques that address target criteria as well as cost and benefit criteria can help engineering designers make better informed choices of materials. Despite the progress has been made in the ranking of materials for target-based criteria, there is no formalized technique for calculating the weighting dependency when target criteria must be taken into account in material selection problems that usually deals with databases. Therefore, to overcome this shortcoming, the strategy of using dependent weightings is extended in this research. Also, an alternative method is proposed to incorporate the correlation, objective, and subjective weightings effectively when there is uncertainty in the importance of three types of weights. This issue is very important for inexperienced designers. The updated procedure is validated through biomedical applications. The first example demonstrates the importance of dependency weighting in amalgam tooth filling material selection and the second one is a hip joint prosthesis material selection problem, which includes target criteria. Furthermore, a model of continuous improvement in product development is outlined, and it is highlighted that the material selection/development is a permanent and endless task for sustainable and profitable growth.
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This paper multi-criteria designing framework of a hybrid photovoltaic (PV)/wind (WT) clean energy system with battery (BA) storage (HPV/WT/BA) considering cost and reliability assessment is presented to supply an annual load base...
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This paper multi-criteria designing framework of a hybrid photovoltaic (PV)/wind (WT) clean energy system with battery (BA) storage (HPV/WT/BA) considering cost and reliability assessment is presented to supply an annual load based on real irradiance and wind speed patterns. The designing goal is optimal sizing of the HPV/WT/BA system with the objective of minimizing the net present cost of clean energy generation (NPCEG) as well as the loss of load and CO2 emission cost with satisfying reliability constraint as energy not supplied probability (ENSP) considering stand-alone and grid-connected modes. Decision making variables include an optimal number of PVs, WTs, batteries, inverter transferred power and PVs angle that is determined optimally using new improved moth flame optimization (IMFO) based on decreasing inertia weight strategy (DIWS) to overcome premature convergence. The design is implemented for various system combinations in stand-alone mode, including HPV/BA, HWT/BA and HPV/WT/ BA systems. The simulation results showed that the HPV/WT/BA is the best combination with the lowest NPCEG and the best ENSP in load supply. The superiority of IMFO is proved compared to conventional MFO and PSO in designing of different combinations in view of cost and reliability in stand-alone mode. Moreover, the results of HPV/WT/BA optimal designing in a grid-connected mode based IMFO showed the less NPCEG and better ENSP compared to stand-alone mode due to network support with purchasing the network power and CO2 environmental waste emission cost minimization. The results showed that variation of network power, reliability constraint and also inverter efficiency has a considerable effect on designing cost and reliability. Moreover, the results illustrated the reduction of NPCEG and reliability enhancement in the condition of Covid-19. (C) 2021 Elsevier Ltd. All rights reserved.
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Explicitly accounting for uncertainties is paramount to the safety of engineering structures. Optimization which is often carried out at the early stage of the structural design offers an ideal framework for this task. When the un...
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Explicitly accounting for uncertainties is paramount to the safety of engineering structures. Optimization which is often carried out at the early stage of the structural design offers an ideal framework for this task. When the uncertainties are mainly affecting the objective function, robust design optimization is traditionally considered. This work further assumes the existence of multiple and competing objective functions that need to be dealt with simultaneously. The optimization problem is formulated by considering quantiles of the objective functions which allows for the combination of both optimality and robustness in a single metric. By introducing the concept of common random numbers, the resulting nested optimization problem may be solved using a general-purpose solver, herein the non-dominated sorting genetic algorithm (NSGA-II). The computational cost of such an approach is however a serious hurdle to its application in real-world problems. We therefore propose a surrogate-assisted approach using Kriging as an inexpensive approximation of the associated computational model. The proposed approach consists of sequentially carrying out NSGA-II while using an adaptively built Kriging model to estimate the quantiles. Finally, the methodology is adapted to account for mixed categorical-continuous parameters as the applications involve the selection of qualitative design parameters as well. The methodology is first applied to two analytical examples showing its efficiency. The third application relates to the selection of optimal renovation scenarios of a building considering both its life cycle cost and environmental impact. It shows that when it comes to renovation, the heating system replacement should be the priority.
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Failure modes and effects analysis (FMEA) is a methodology for prioritizing actions to mitigate the effects of failures in products and processes. Although originally used by product designers, FMEA is currently more widely used i...
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Failure modes and effects analysis (FMEA) is a methodology for prioritizing actions to mitigate the effects of failures in products and processes. Although originally used by product designers, FMEA is currently more widely used in industry in Six Sigma quality improvement efforts. Two prominent criticisms of the traditional application of FMEA are that the risk priority number (RPN) used to rank failure modes is an invalid measure according to measurement theory, and that the RPN does not weight the three decision criteria used in FMEA. Various methods have been proposed to mitigate these concerns, including many using fuzzy logic. We develop a new ranking method in this article using a data-elicitation technique. Furthermore, we develop an efficient means of eliciting data to reduce the effort associated with the new method. Subsequently, we conduct an experimental study to evaluate that proposed method against the traditional method using RPN and against an approach using fuzzy logic.
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Design flood, which plays a paramount role in reservoir construction and operation, is often calculated by the annual maximum sampling method (AMSM). However, the AMSM can only use a small amount of data and reflect the extreme va...
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Design flood, which plays a paramount role in reservoir construction and operation, is often calculated by the annual maximum sampling method (AMSM). However, the AMSM can only use a small amount of data and reflect the extreme value distribution of inflow flood. As a result, the annual maximum design flood or the seasonal design flood is not sufficient to formulate the reservoir operation scheme in whole life cycle. Currently, studies analyzing the sample selection method of design flood and the way to make design flood close to inflow flood are rare. To this end, an improved peaks-over-threshold method (IPOT) was designed. Together with the time-varying parameters with Poisson distribution model, we used the IPOT to calculate a new type time-varying design flood in this study and took Longyangxia Reservoir in China as a case study. Results indicate that, compared with the AMSM, the IPOT enhances the physical correlation between sample individuals by increasing data use rate and determines the optimal threshold, which avoids the influence of human factors on the sample selection. Moreover, the time-varying design flood can fully reflect the characteristics of inflow flood and combine the design flood value with time and probability to establish an inflow flood identification model. According to this model, managers can assess the probability and type of inflow flood and choose the appropriate reservoir operation scheme. Findings of this study, including the IPOT, the time-varying design flood and the inflow flood identification model are helpful for water resources planning and management.
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The problem of delayed input control for a nonlinear system is discussed, where the nonlinearities of nonlinear systems are not assumed as Lipschitz continuous, they can be non Lipschitz continuous or discontinuous in this paper. ...
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The problem of delayed input control for a nonlinear system is discussed, where the nonlinearities of nonlinear systems are not assumed as Lipschitz continuous, they can be non Lipschitz continuous or discontinuous in this paper. Notice that as a general nonlinear system, its sub-systems may have no common equilibrium or no equilibriums, but their trajectories may still be kept near equilibriums. Motivated by this, practical stability of nonlinear systems is considered by employing the Lyapuov method. Practical stability criteria in forms of linear matrix inequalities are obtained, where improved integral inequalities are given to reduce the conservatism of the obtained results. Finally, the obtained results are applied to analyze two problems of load frequency control of a one-area networked power system with sampled input and flight control of a two-degree-freedom helicopter system. The advantage and effectiveness of our approach are shown by a comparison with the literature. (c) 2022 Elsevier Inc. All rights reserved.
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