Support structure,a critical component in the design for additive manufacturing(DfAM),has been largely overlooked by additive manufacturing(AM)communities.The support structure stabilises overhanging sections,aids in ...Support structure,a critical component in the design for additive manufacturing(DfAM),has been largely overlooked by additive manufacturing(AM)communities.The support structure stabilises overhanging sections,aids in heat dissipation,and reduces the risk of thermal warping,residual stress,and distortion,particularly in the fabrication of complex geometries that challenge traditional manufacturing methods.Despite the importance of support structures in AM,a systematic review covering all aspects of the design,optimisation,and removal of support structures remains lacking.This review provides an overview of various support structure types—contact and non-contact,as well as identical and dissimilar material configurations—and outlines optimisation methods,including geometric,topology,simulation-driven,data-driven,and multi-objective approaches.Additionally,the mechanisms of support removal,such as mechanical milling and chemical dissolution,and innovations like dissolvable supports and sensitised interfaces,are discussed.Future research directions are outlined,emphasising artificial intelligence(AI)-driven intelligent design,multi-material supports,sustainable support materials,support-free AM techniques,and innovative support removal methods,all of which are essential for advancing AM technology.Overall,this review aims to serve as a foundational reference for the design and optimisation of the support structure in AM.展开更多
In lighting design,mean room surface exitance(MRSE)has been known as an indicator of the adequacy of illumination in an indoor space.Recent studies have suggested an exponential model relating MRSE and the observer’s...In lighting design,mean room surface exitance(MRSE)has been known as an indicator of the adequacy of illumination in an indoor space.Recent studies have suggested an exponential model relating MRSE and the observer’s retinal response.This is particularly applicable in a room with homogenous room surface reflectance and a constant total corneal illuminance,which is the total illuminance received at the eye.However,accuracy of the exponential model is yet to be assessed in detail.Furthermore,the implication on interior lighting design is also yet to be quantified.This study thus aims to assess the accuracy of the exponential model and to optimise the output variables.Random computations using Monte Carlo simulation are performed for various input variables,followed with sensitivity and uncertainty analyses and optimisation.Prediction errors of the exponential model are found between-10%and 6%.The MRSE is highly influenced by surface reflectance,whereas the total corneal illuminance is influenced by the source luminous flux.Optimum design parameters are obtained by minimising the ratio between total corneal illuminance and MRSE.Overall,this study provides guidelines in lighting design practice for enhancing room spatial brightness while minimising energy use.展开更多
Aircraft engine design is a complicated process,as it involves huge number of components.The design process begins with parametric cycle analysis.It is crucial to determine the optimum values of the cycle parameters t...Aircraft engine design is a complicated process,as it involves huge number of components.The design process begins with parametric cycle analysis.It is crucial to determine the optimum values of the cycle parameters that would give a robust design in the early phase of engine development,to shorten the design cycle for cost saving and man-hour reduction.To obtain a robust solution,optimisation program is often being executed more than once,especially in Reliability Based Design Optimisations(RBDO)with Monte-Carlo Simulation(MCS)scheme for complex systems which require thousands to millions of optimisation loops to be executed.This paper presents a fast heuristic technique to optimise the thermodynamic cycle of two-spool separated flow turbofan engines based on energy and probability of failure criteria based on Luus-Jaakola algorithm(LJ).A computer program called Turbo Jet Engine Optimiser v2.0(TJEO-2.0)has been developed to perform the optimisation calculation.The program is made up of inner and outer loops,where LJ is used in the outer loop to determine the design variables while parametric cycle analysis of the engine is done in the inner loop to determine the engine performance.Latin-Hypercube-Sampling(LHS)technique is used to sample the design and model variations for uncertainty analysis.The results show that optimisation without reliability criteria may lead to high probability of failure of more than 11%on average.The thrust obtained with uncertainty quantification was about 25%higher than the one without uncertainty quantification,at the expense of less than 3%of fuel consumption.The proposed algorithm can solve the turbofan RBDO problem within 3 min.展开更多
Equipped with its Solver and-in and VBA, Microsoft Excel makes an ideal educational platform for design analyses of fluid-thermal systems. This paper illustrates this capability by considering a common type of these s...Equipped with its Solver and-in and VBA, Microsoft Excel makes an ideal educational platform for design analyses of fluid-thermal systems. This paper illustrates this capability by considering a common type of these systems;which is the double-pipe heat exchanger. While Solver is used for the optimisation analysis, VBA is used for the development of a user-defined function (UDF) that determines the optimum standard-pipe size for the system.展开更多
Efficiency and accuracy have been challenging in the design optimisation process driven by building simulation. The literature review identified the limitations of previous studies, prompting this study to explore the...Efficiency and accuracy have been challenging in the design optimisation process driven by building simulation. The literature review identified the limitations of previous studies, prompting this study to explore the performance of single-objective versus multi-objective efficiency and accuracy on equivalent problems based on control variables and to consider more algorithmic options for a broader range of designs. This study constructed a comparative energy-related experiment whose results are in the same unit, either as a single-objective optimisation or split into two objectives. The project aims to reduce annual energy consumption and increase solar utilisation potential. Our approach focuses on the use of a surrogate modelling algorithm, Radial Basis Function Optimisation Algorithm(RBFOpt),with its multi-objective version RBFMOpt, to optimise the energy performance while quickly identifying new energy requirements for an iterative office building design logic, contrast to traditional genetic-algorithm-driven. In addition, the research also conducted a comparative study between RBFOpt and Covariance Matrix Adaptation Evolutionary Strategies(CMAES) in a single-objective comparison and between RBFMOpt and Nondominated Sorting Genetic Algorithm Ⅱ(NSGA-Ⅱ) in a multi-objective optimisation process. The comparison of these sets of Opt algorithms with evolutionary algorithms helps to provide data-driven evidence to support early design decisions.展开更多
The acoustic environment of the classroom is one of the most important factors influencing the teaching and learning effects of the teacher and students.It is critical to ensure good speech intelligibility in classroo...The acoustic environment of the classroom is one of the most important factors influencing the teaching and learning effects of the teacher and students.It is critical to ensure good speech intelligibility in classrooms.However,due to some factors,it may not be easy to achieve an ideal classroom acoustic environment,especially in large-scale multimedia classrooms.In a real renovation project of 39 multimedia classrooms in a university,seven typical rooms were selected,and the acoustic environment optimisation design and verification for these multimedia classrooms were performed based on simulation.First,the acoustic and sound reinforcement design schemes were determined based on the room acoustics software ODEON.Next,the effects of the optimisation design were analysed,and the simulated and measured results were compared;the accuracy of using the reduced sound absorption coefficients,which were determined empirically,was also examined.Finally,the recommended reverberation times(RTs)in multimedia classrooms corresponding to speech intelligibility were discussed,the effectiveness of the speech transmission index(STI)as a primary parameter for classroom acoustic environment control was considered,and the acoustic environment under the unoccupied and occupied statuses was compared.The results revealed that although there are many factors influencing the effect of classroom acoustic environment control,an adequate result can be expected on applying the appropriate method.Considering both the acoustic design and visual requirements also makes the classroom likely to have a good visual effect in addition to having a good listening environment.展开更多
Architects welcome double skin facade(DSF)due to its aesthetic quality.The first DSF structure was intended to prevent cold weather and strong winds.Nowadays,the application of DSF under different climates has been in...Architects welcome double skin facade(DSF)due to its aesthetic quality.The first DSF structure was intended to prevent cold weather and strong winds.Nowadays,the application of DSF under different climates has been investigated in many previous studies.Fiowever,little work had been done on the behaviour of DSF in hot and humid climates.Therefore,this paper aimed to extend the application into this specific climate and Guangzhou was selected as the sample city.Both the climate and the design influence the performance of DSF.In this paper,rather than explore how each design parameter influences the performance,the design was evaluated from an overall aspect.The Designbuilder software was used to build the single skin facade(SSF)and double skin facade base model.Annual HVAC energy consumption for both the two models was calculated and compared.An optimisation process was conducted to figure out what kinds of parameter combination could make the design more energy-saving and thermally comfortable.The results indicated that it was possible to design an energy-saving DSF system applied in hot and humid climates compared with the SSF model.The efficiency of the DSF could be further enhanced with a better parameter combination.The optimised options had some features in common,which could provide some inspirations for the application of DSF in hot and humid climates.展开更多
基金supported by the Advanced Research and Technology Innovation Centre (ARTIC)the National University of Singapore under Grant (Project Number:ADTRP1)the sponsorship of the China Scholarship Council (No. 202306130143).
文摘Support structure,a critical component in the design for additive manufacturing(DfAM),has been largely overlooked by additive manufacturing(AM)communities.The support structure stabilises overhanging sections,aids in heat dissipation,and reduces the risk of thermal warping,residual stress,and distortion,particularly in the fabrication of complex geometries that challenge traditional manufacturing methods.Despite the importance of support structures in AM,a systematic review covering all aspects of the design,optimisation,and removal of support structures remains lacking.This review provides an overview of various support structure types—contact and non-contact,as well as identical and dissimilar material configurations—and outlines optimisation methods,including geometric,topology,simulation-driven,data-driven,and multi-objective approaches.Additionally,the mechanisms of support removal,such as mechanical milling and chemical dissolution,and innovations like dissolvable supports and sensitised interfaces,are discussed.Future research directions are outlined,emphasising artificial intelligence(AI)-driven intelligent design,multi-material supports,sustainable support materials,support-free AM techniques,and innovative support removal methods,all of which are essential for advancing AM technology.Overall,this review aims to serve as a foundational reference for the design and optimisation of the support structure in AM.
基金funded by the Ministry of Education,Culture,Research,and Technology of the Republic of Indonesia,under grant number 317/UN40.LP/PT.01.03/2021,under LPPM Universitas Pendidikan Indonesia(UPI).
文摘In lighting design,mean room surface exitance(MRSE)has been known as an indicator of the adequacy of illumination in an indoor space.Recent studies have suggested an exponential model relating MRSE and the observer’s retinal response.This is particularly applicable in a room with homogenous room surface reflectance and a constant total corneal illuminance,which is the total illuminance received at the eye.However,accuracy of the exponential model is yet to be assessed in detail.Furthermore,the implication on interior lighting design is also yet to be quantified.This study thus aims to assess the accuracy of the exponential model and to optimise the output variables.Random computations using Monte Carlo simulation are performed for various input variables,followed with sensitivity and uncertainty analyses and optimisation.Prediction errors of the exponential model are found between-10%and 6%.The MRSE is highly influenced by surface reflectance,whereas the total corneal illuminance is influenced by the source luminous flux.Optimum design parameters are obtained by minimising the ratio between total corneal illuminance and MRSE.Overall,this study provides guidelines in lighting design practice for enhancing room spatial brightness while minimising energy use.
基金The project is funded by the Ministry of Higher Education Malaysia,under the Fundamental Research Grant Scheme(FRGS Grant No.FRGS/1/2017/TK07/SEGI/02/1).
文摘Aircraft engine design is a complicated process,as it involves huge number of components.The design process begins with parametric cycle analysis.It is crucial to determine the optimum values of the cycle parameters that would give a robust design in the early phase of engine development,to shorten the design cycle for cost saving and man-hour reduction.To obtain a robust solution,optimisation program is often being executed more than once,especially in Reliability Based Design Optimisations(RBDO)with Monte-Carlo Simulation(MCS)scheme for complex systems which require thousands to millions of optimisation loops to be executed.This paper presents a fast heuristic technique to optimise the thermodynamic cycle of two-spool separated flow turbofan engines based on energy and probability of failure criteria based on Luus-Jaakola algorithm(LJ).A computer program called Turbo Jet Engine Optimiser v2.0(TJEO-2.0)has been developed to perform the optimisation calculation.The program is made up of inner and outer loops,where LJ is used in the outer loop to determine the design variables while parametric cycle analysis of the engine is done in the inner loop to determine the engine performance.Latin-Hypercube-Sampling(LHS)technique is used to sample the design and model variations for uncertainty analysis.The results show that optimisation without reliability criteria may lead to high probability of failure of more than 11%on average.The thrust obtained with uncertainty quantification was about 25%higher than the one without uncertainty quantification,at the expense of less than 3%of fuel consumption.The proposed algorithm can solve the turbofan RBDO problem within 3 min.
文摘Equipped with its Solver and-in and VBA, Microsoft Excel makes an ideal educational platform for design analyses of fluid-thermal systems. This paper illustrates this capability by considering a common type of these systems;which is the double-pipe heat exchanger. While Solver is used for the optimisation analysis, VBA is used for the development of a user-defined function (UDF) that determines the optimum standard-pipe size for the system.
基金National Natural Science Foundation of China(Grant Nos.51978144,51978147)。
文摘Efficiency and accuracy have been challenging in the design optimisation process driven by building simulation. The literature review identified the limitations of previous studies, prompting this study to explore the performance of single-objective versus multi-objective efficiency and accuracy on equivalent problems based on control variables and to consider more algorithmic options for a broader range of designs. This study constructed a comparative energy-related experiment whose results are in the same unit, either as a single-objective optimisation or split into two objectives. The project aims to reduce annual energy consumption and increase solar utilisation potential. Our approach focuses on the use of a surrogate modelling algorithm, Radial Basis Function Optimisation Algorithm(RBFOpt),with its multi-objective version RBFMOpt, to optimise the energy performance while quickly identifying new energy requirements for an iterative office building design logic, contrast to traditional genetic-algorithm-driven. In addition, the research also conducted a comparative study between RBFOpt and Covariance Matrix Adaptation Evolutionary Strategies(CMAES) in a single-objective comparison and between RBFMOpt and Nondominated Sorting Genetic Algorithm Ⅱ(NSGA-Ⅱ) in a multi-objective optimisation process. The comparison of these sets of Opt algorithms with evolutionary algorithms helps to provide data-driven evidence to support early design decisions.
基金This study was supported by the National Natural Science Foundation of China(No.51778100,No.11774266,No.51878110,No.51278078).
文摘The acoustic environment of the classroom is one of the most important factors influencing the teaching and learning effects of the teacher and students.It is critical to ensure good speech intelligibility in classrooms.However,due to some factors,it may not be easy to achieve an ideal classroom acoustic environment,especially in large-scale multimedia classrooms.In a real renovation project of 39 multimedia classrooms in a university,seven typical rooms were selected,and the acoustic environment optimisation design and verification for these multimedia classrooms were performed based on simulation.First,the acoustic and sound reinforcement design schemes were determined based on the room acoustics software ODEON.Next,the effects of the optimisation design were analysed,and the simulated and measured results were compared;the accuracy of using the reduced sound absorption coefficients,which were determined empirically,was also examined.Finally,the recommended reverberation times(RTs)in multimedia classrooms corresponding to speech intelligibility were discussed,the effectiveness of the speech transmission index(STI)as a primary parameter for classroom acoustic environment control was considered,and the acoustic environment under the unoccupied and occupied statuses was compared.The results revealed that although there are many factors influencing the effect of classroom acoustic environment control,an adequate result can be expected on applying the appropriate method.Considering both the acoustic design and visual requirements also makes the classroom likely to have a good visual effect in addition to having a good listening environment.
基金supported by the Key Research and Development Program of Anhui Province(No.S202004a07020029).
文摘Architects welcome double skin facade(DSF)due to its aesthetic quality.The first DSF structure was intended to prevent cold weather and strong winds.Nowadays,the application of DSF under different climates has been investigated in many previous studies.Fiowever,little work had been done on the behaviour of DSF in hot and humid climates.Therefore,this paper aimed to extend the application into this specific climate and Guangzhou was selected as the sample city.Both the climate and the design influence the performance of DSF.In this paper,rather than explore how each design parameter influences the performance,the design was evaluated from an overall aspect.The Designbuilder software was used to build the single skin facade(SSF)and double skin facade base model.Annual HVAC energy consumption for both the two models was calculated and compared.An optimisation process was conducted to figure out what kinds of parameter combination could make the design more energy-saving and thermally comfortable.The results indicated that it was possible to design an energy-saving DSF system applied in hot and humid climates compared with the SSF model.The efficiency of the DSF could be further enhanced with a better parameter combination.The optimised options had some features in common,which could provide some inspirations for the application of DSF in hot and humid climates.
