Optimal Design Solutions Research Articles

Multi-objective optimization for a novel sandwich corrugated square tubes

The sandwich corrugated square tubes (SCSTs), which includes outer square tube (OST), inner square tube (IST) and middle corrugated square tube (CST), have been has been proved to have excellent energy absorption performances. In order to further increase its performance and obtain the optimal structural parameters, multi-objective optimization of SCSTs is carried out. The surrogate modals for the SCSTs were constructed, and the main effects and the interaction effects were analyzed in detail. Finally, multi-objective particle swarm (MOPSO) optimization was used for multi-objective optimization of the SCSTs. The optimization results show that Pareto frontier of the SCSTs can reach a larger range than the SCSTs with A = 0 mm. Due to the coupling effect, energy absorption (EA) and initial peak force (Fmax) of the optimal design solution of the SCSTs are increased by 13.76% and decreased by 8.76% respectively compared to the sum of IST, OST and CST crushing alone. Two key indicators, including Fmax and EA, have been improved at the same time.

Optimized design and integration of energy storage in Solar-Assisted Ground-Source Heat Pump systems

The integrated use of multiple renewable energy sources to increase the efficiency of heat pump systems, such as in Solar Assisted Geothermal Heat Pumps (SAGHP), may lead to significant benefits in terms of increased efficiency and overall system performance especially in extreme climate contexts, but requires careful integrated optimization of the different system components. In particular, thermal storages take a fundamental role in optimizing the integration of renewable energy sources and the system operation. This work investigates the potential design optimization of a SAGHP system in a mountain site by exploring many different alternatives to optimize the mutual relationship between the solar field, the geothermal field and the water thermal storages. This is done through an original simulation-based multi-objective optimization framework considering energy efficiency and economic feasibility, which allows appraising the impact of the different design alternatives on the overall system performance and on the dynamics of the different system components. Results identify a set of optimized system configurations that optimize the integrated exploitation of the different thermal sources showing a potential increase of the overall system performance leading to 34% lower global cost compared to the initial design. High robustness of the optimal design solutions is reported with respect to the current context of high economic uncertainty.

Harnessing Multi-Domain Knowledge for User-Centric Product Conceptual Design

Abstract Conceptual design is the design phase that deploys product functions and structures based on user requirements and ultimately generates conceptual design solutions. The increasing diversification of products has led to the promotion of customized design that involves deep user participation. As a result, there has been a growing focus on user-centric conceptual design. In this regard, the relationship among users, designers, and design solutions has been changed, which has brought challenges to the traditional designer-oriented design model. To address the complex understanding and decision-making problem caused by deeper user participation, emerging new user-centric product conceptual design model needs to be discussed. In the new design model, addressing the changing or growing requirements of users through the design of solutions and leveraging multi-domain knowledge to guide the conceptual design process are the critical areas of focus. To further describe this design model, this paper examines the user-centric interconnection among users, designers, design solutions, and multi-domain knowledge. In order to optimize design solutions, the solution resolution process and knowledge mapping based on design deviations are considered effective approaches. In addition, the paper also presents the types of design deviations and the multi-domain knowledge support techniques.

Applying Latent Dirichlet Allocation and Support Vector Regression to the Aesthetic Design of Medical Nursing Beds

Abstract With the development of social productivity and the improvement in material living standards, emotional value has become the core driver of the enhancement of product market competitiveness. A medical nursing bed, one of the most typical types of medical devices, is designed with little attention to the emotional experience of the users. Therefore, this paper proposes an innovative perceptual design approach under the Kansei engineering (KE) framework for resource-limited and information-poor companies. It guides the aesthetic design of medical nursing beds by constructing a mapping relationship between users’ perceptual needs and the design characteristics of medical nursing beds to maximize users’ emotions. First, latent Dirichlet allocation (LDA) is used to extract usable Kansei semantics from big data, compensating for the subjectivity of traditional KE data input. Then, the design characteristics obtained after deconstructing a medical nursing bed are simplified with rough set theory (RST). Finally, a mapping model between users’ perceptual needs and the core design characteristics of nursing beds is established through support vector regression (SVR), and the optimal design solution is obtained by weighting calculation. The optimal combination of design characteristics for medical nursing beds is finally obtained. The results suggest that the design method proposed in this paper can help designers accurately grasp users’ emotional perceptions in terms of aesthetic design and scientifically guide and complete the design of new medical nursing beds, verifying the feasibility and scientificity of the proposed method in terms of aesthetic design.

Critical indoor environmental factors affecting productivity: perspectives from university staff and postgraduate students

ABSTRACT Indoor environmental quality (IEQ) of buildings plays an important role in affecting building occupants’ comfort, health and well-being. However, there is limited understanding of the critical IEQ factors that affect occupants’ work productivity in university office buildings. By surveying 204 people (72 university staff members and 132 postgraduate students) in a tertiary education institution in New Zealand, this research aimed to identify and rank the critical IEQ factors concerning their perceived productivity and how the perceived importance of these factors differed between staff and student cohorts. Statistical analysis identified a total of 16 IEQ factors as important in affecting work productivity, and 15 of them, except cleanliness of the office, could be grouped into four categories: (1) thermal comfort and lighting; (2) acoustics and privacy comfort; (3) spatial comfort and (4) aesthetics and views. Based on the identified critical IEQ factors, a framework was developed and can be used by building facility managers and designers in the tertiary education sector to optimize design solutions to improve building performance that is more conducive to their occupants. The findings from this research can inform the inclusion of design features that will enable staff and students using these buildings to achieve better productivity.

Development of a Multi-Objective Optimal Design Approach for Combined Water Systems

Recently, due to extreme climate change, damage from flooding has been increasing; however, water shortages are being announced simultaneously. Moreover, the water distribution system’s ability to supply consumers is being overwhelmed because of urbanization, population concentration, and increases in water consumption. For this reason, to solve the water shortage problem, water reuse technologies are developing and improving that perform simple chemical treatment processes to reuse water for flushing toilets, washing, gardening, etc. but not as drinking water. However, most water reuse systems are designed and operated as independent systems, such as reusing water used in individual buildings or using rainwater. Therefore, this study develops an optimal design for the combined water systems, which is modeling and designing water distribution systems, urban drainage systems, and water reuse systems simultaneously to solve the water shortage and reduce flooding damage. To consider the combined water systems design, the existing water distribution system (WDS) demand is divided into drinking water and other uses, and the resource of other water is assumed by the rainwater storage tank for covering the amount of exceeding precipitation. To derive optimal design solutions for the combined three water systems, single- and multi-objective optimization techniques are applied considering various design criteria (i.e., construction cost, system resilience, and flooding volume on the exceeding design rainfall intensity). The developed combining water system design techniques could be used to create designs that solve the problems of medium and long-term water shortages and sustainable water systems development.

Multi-objective economic and environmental assessment for the preliminary design of CO2 transport pipelines

A methodology based on the multi-objective optimisation of economic and environmental aspects is presented to support the preliminary design of CO2 transport pipelines employed as part of Carbon Capture and Storage (CCS) systems. Pareto optimal design solutions are determined for a realistic point-to-point CO2 pipeline using Level Diagrams and choosing the Nominal Pipe Size (NPS) as a decision variable. A quantitative procedure entailing the definition of economic and environmental key performance indicators is defined to allow the identification of an optimum pipeline design. The outcome is compared against the minimisation of single-objective indicators based on the CO2 avoided and carbon pricing concepts. The results of a case-study concerning a 70 km long pipeline transporting 10 Mt yr−1 of supercritical CO2 show that the multi-objective method yields an optimum NPS equal to 30, higher than the NPS 28 deriving from the alternative indexing methods. The proposed multicriteria approach effectively considers case-specific environmental sustainability constraints, which result in determining 46% of the overall performance measure of the identified optimum solution. The results show that conventional single-objective methods underestimate the contribution of environmental factors up to 2.6% of the overall performance index value. A Monte Carlo probabilistic analysis is performed to verify the robustness of the results with respect to the possible uncertainties.

INTEGRATED APPROACH TO ENERGY EFFICIENT BUILDING DESIGNING BASED ON BIM

Problem statement. The design of energy efficient buildings requires compliance with a number of criteria. The use of energy efficient constructions and building materials, the use of energy efficient engineering solutions and high performance equipment can more than halve a building's resource consumption. But it is important to select and define the characteristics individually. A real estate object must therefore, first of all, be designed correctly. Calculated designs, reasonably selected building materials and correct calculations from thermal engineering calculators do not guarantee obtaining a heat-insulating and vapor-insulating envelope without gaps. Due to the complexity of the construction object, it is problematic to identify thermal bridges and take into account weak points without an integrated approach to the design of the future building. The climate, geographical location and terrain must also be taken into account. In order to carefully select the optimal design solution, it is necessary to take a large array of data related to energy efficiency indicators. In classic design systems, such information is not displayed or analyzed. It is very difficult to assess the energy efficiency of the project. The technology of building information modeling, or BIM, makes it possible to radically simplify the task of designing energy efficient buildings. The purpose of the article is to substantiate the use of modern programs based on VIM technologies at the stage of energy efficient building design, to determine the criteria for selecting a software complex that will allow you to perform building simulation, calculate energy efficiency indicators, analyze thermal bridges, visualize the results, and issue a package of working documentation within the framework of one program. Demonstrate a highly detailed three-dimensional model of the building enriched with maximum information: data on the thermal conductivity of building materials and technical characteristics of equipment.

A novel tuned inerter eddy current damper: modeling, optimization, and evaluation

This study proposes a novel tuned inerter eddy current damper using a rack and gear mechanism (TIECD), in which the configuration and mechanical model are introduced in detail. The TIECD design procedure for the seismic control of primary structures is established based on the effective damping ratio enhancement (EDRE) effect. A closed-form solution for TIECD optimal design under white noise excitation is presented using stochastic linearization techniques (SLT) with force-based and energy-based equivalence criteria. The control performance of the TIECD obtained by the closed-form solution, including the EDRE effect and effective damping ratio, is in good agreement with the numerical results obtained from the Monte Carlo simulation when a suitable TIECD critical velocity is selected; a large critical velocity is conducive to improving the accuracy of the closed-form solution. Note that the effect of a low structural damping level on the optimal design of TIECD can be ignored, which is beneficial in practical engineering applications because structural damping cannot be precisely known in most cases. Furthermore, several numerical studies have been conducted to investigate the availability of TIECD under real seismic excitations. The results indicate that the effectiveness of TIECD in mitigating the seismic response of primary structures is approximately the same as that of a tuned viscous mass damper (TVMD) and much greater than that of the viscous and eddy current dampers with the same damping parameters. It can be considered that the maximum damping force and maximum deformation of TIECD and TVMD are the key design factors for short-period and long-period structures, respectively, and the advantages of TIECD over TVMD are owing to the damping force limiting characteristics and small deformation.

Multi-criteria optimization approach to the design of small dams’ systems along mountainous stream beds

Abstract This paper aims at the optimal design of a system of small solid barrier-type stone dams in a semi-realistic study case, determining the number, location and height of dams and a borrow-pit (BP)'s location for benefit maximization and cost minimization of objectives: (a) maximum flood protection, (b) maximum underlying aquifers' artificial recharge, (c) minimum dams' construction cost and (d) minimum stonework transportation cost. The simplified conceptual model involves no hydraulic simulation; flow characteristics are not considered, while no dam is assumed to affect another dam's benefit/cost values. Hence, all partial benefit/cost values can be separately pre-calculated, for each one of the available dam locations for all available heights and BP locations, deriving from data concerning topography, geology/soil, land uses, construction and transportation costs. Any solution proposing a system of dams of various heights and a BP exhibits a total management value equal to the sum of the respective partial benefit/cost values of each dam. The multi-objective optimization problem is formulated into a single-objective minimization problem; the difference of costs minus benefits is to be minimized. Simple, elitist genetic algorithms (GAs) are used, coupled with sophisticated post-processing of results, able to produce optimized design solutions and strategies.

Evaluating the impact of the center control touch screen of new energy vehicles on user visual imagery and preferences

In recent years, with the changes in the international energy situation, new energy vehicles (NEVs) have become an essential choice for people to travel. The center control touch screen (CCTS) of NEVs is an important part of the user's interaction with the vehicle, which is quite different from a conventional fuel vehicle. Therefore, it is necessary to conduct research on the CCTS of NVEs. This study integrates multiple research methods to investigate the visual imagery and user preferences for CCTSs in NEVs. The results of the study show that the horizontal version with small rounded angles without a border is the optimal design solution for the visual imagery dimension, whereas the vertical version with large rounded angles and a border is the worst design solution in terms of the visual imagery dimension. The design without a border can increase users' preference and purchase intention to a certain extent. The results of the above study can effectively reflect the potential user demand for NEVs’ CCTSs, which also has positive implications for enhancing the overall user experience of NEVs.

Wastewater reuse and energy saving require a more decentralized urban wastewater system? Evidence from multi-objective optimal design at the city scale

Decentralization is recognized as an emerging solution for a more sustainable urban wastewater system (UWS) for the future. However, the debate of centralization vs. decentralization at the system's planning stage remains unresolved, mainly due to the complexity of the system's spatial structure and the multiple design objectives, such as water reuse and energy conservation. This paper presents the Sustainable Urban Wastewater System Generator (SUWStor) as a tool to address this issue. Integrating a graph representation of the system structure and the ant colony algorithm, SUWStor can produce Pareto optimal solutions for system design under three objectives: minimizing the capital cost, minimizing the operational energy consumption, and maximizing the water reuse capacity. The model is used for system design in a 100-square-km new city, the Xiong'an New District in China. Compared to the solution based on human experience, the model can reduce the system's capital cost by 7% and the operational energy in the pipe network by 26%, while maintaining the water reuse capacity at 100%. With this model, the relation between the optimal system layout and the choice over different design objectives can be discussed for any given area. In our case study, the optimal capacity of WWTPs for the lowest-cost solution is 48,000 m3 per day, leading to a total number of WWTPs of 5. As the water reuse level increases to maximum, the optimal capacity reduces to 15,000 m3 per day, where the number of WWTPs is 16. The model is also able to perform significantly better than the locally optimized results, in which only the WWTP locations are fixed at their optimal values. This demonstrates the importance of a global optimization model in designing the integrated UWS.

Compressibility characteristics of clays in the Red River Delta

The Red River Delta (RRD) is the second largest delta in Vietnam and is a significant economic zone in the country, encompassing important cities and economic zones. Geologically, the delta consists of clay layers distributed all over its area, which strongly impact the foundation designs of the infrastructure system (e.g., highways, industrial parks, harbors). However, up to date, there were no comprehensive studies on the compressibility characteristics of the clays in the delta. This study presents a primary study on some compressibility characteristics of clays in the whole delta with an emphasis on the use of CPTu data in the interpretation. For this, high-quality field and laboratory test results obtained from four research test sites and eight project sites were analyzed to depict the characteristics. The results indicate that the clays in the delta are typically soft to medium stiff and normally consolidated to slightly overconsolidated, which represent typical characteristics of young Holocene deposits. The compression index (Cc) of the clays was found to have good correlations with natural water content (Wn) or in-situ void ratio (e0). The ratio of radial coefficient of consolidation from a consolidation test with a central drain (CD) to the vertical coefficient of consolidation from the standard consolidation test (i.e., cr,CD/cv) from the 4 research test sites is on average 2.76 (log t method) and 2.32 (root t method) and these average ratios are found typical for deltaic soil deposits. The correlations for the remolded samples indicate that the drainage type has a strong influence to the induced coefficients of homogeneously remolded soils. Results from this study help geotechnical engineers have a general view on the compressibility characteristics of the clays in the delta, which in turn helps secure optimal foundation design solutions.

Applying Evolutionary Computation to Optimize the Design of Urban Blocks

This empirical study in this paper focuses on the application of evolutionary computation in parametric urban block design to solve the problem of how to effectively find the optimal design solution set among a large number of schemes obtained through parametric urban block design. Through the application of evolutionary computation, a set of parameterized intelligent generation methods of urban blocks under the guidance of multi-conflict objective optimization can be established. The empirical study presented is based on a typical Russian block redevelopment design along the Chinese Eastern Railway. The design aims to transform and redevelop the original block on the basis of protecting its historical buildings and street pattern, taking into account environmental and economic considerations. The final results show that under the premise of reasonable overall evolution, a large number of block design schemes with complex design objectives can be obtained. Furthermore, according to the index data analysis of Pareto’s overall optimal, mean value, median value, extreme value, etc., it provides designers with methods to select a series of optimal schemes quickly and efficiently based on different factors such as comprehensive balance, average and middle ranking, and individual best.

Risk-Based Hybrid Light-Weight Ship Structural Design Accounting for Carbon Footprint

The study aims to develop an integrating risk-based formulation and cost-benefit analysis for identifying an optimal ship hull structural design solution where the steel cargo holds aluminium honeycomb sandwich panels to replace inner side shells. The risk of progressive structural failure includes hazards related to environmental pollution due to accidental fuel and oil spills, possible loss of cargo, crew members and ship during operations, and air pollution during shipyard construction and ship voyages. The structural failure incorporates progressive time-dependent structural degradation coupled with ship hull load-carrying capacity in predicting structural integrity during the service life. The ship hull structural failure and associated risk are estimated over the ship’s service life as a function of the design solution. The carbon footprint and cost to mitigate the impact for the entire steel and hybrid ship hull structural solution implemented as a sustainable life cycle solution are analysed where the steel ship hull structure is built through primary construction. The cost of structural measures accounts for redesigning the ship structure and implementing aluminium honeycomb composite panels instead of steel plates, reducing steel weight, environmental pollution and cost and increasing the transported cargo and corrosion degradation resistance. It has been found that design solutions AHS1 and AHS2, in which aluminium honeycomb panels replace the inner steel shell plates, enhance the corrosion degradation resistance, and reduce the ship hull’s lightweight, reflecting a better beta-reliability index at the time of the first repair with a lower repair cost and more transported cargo. The cost of the ship associated with the design solutions AHS1 and AHS2 is about 11% lower than the steel solutions.

Large-Scale Bayesian Optimal Experimental Design with Derivative-Informed Projected Neural Network

We address the solution of large-scale Bayesian optimal experimental design (OED) problems governed by partial differential equations (PDEs) with infinite-dimensional parameter fields. The OED problem seeks to find sensor locations that maximize the expected information gain (EIG) in the solution of the underlying Bayesian inverse problem. Computation of the EIG is usually prohibitive for PDE-based OED problems. To make the evaluation of the EIG tractable, we approximate the (PDE-based) parameter-to-observable map with a derivative-informed projected neural network (DIPNet) surrogate, which exploits the geometry, smoothness, and intrinsic low-dimensionality of the map using a small and dimension-independent number of PDE solves. The surrogate is then deployed within a greedy algorithm-based solution of the OED problem such that no further PDE solves are required. We analyze the EIG approximation error in terms of the generalization error of the DIPNet and show they are of the same order. Finally, the efficiency and accuracy of the method are demonstrated via numerical experiments on OED problems governed by inverse scattering and inverse reactive transport with up to 16,641 uncertain parameters and 100 experimental design variables, where we observe up to three orders of magnitude speedup relative to a reference double loop Monte Carlo method.

Pareto front generation for integrated drive-train and structural optimisation of a robot manipulator conceptual design via NSGA-II

Due to the complexity of the process, there is no single solution for determining the motors, gearboxes and structures of a robot manipulator according to the desired dynamic performance while minimising both the deflections in the structure during the dynamic motion and total robot weight. The solution of this integrated drive-train and dynamic structural optimisation problem is generalised for three degrees of freedom (DOF) robot manipulator via Non-Dominated Sorting Genetic Algorithm II (NSGA-II) to obtain the Pareto front of any desired robot manipulator overall conceptual design, including motors, gearboxes and thicknesses of the links. A flexible body dynamic simulation model was created in the MATLAB Simmechanics environment. The flexible bodies were defined via lumped parameter estimation method, which allows observation of the deflections in links during the dynamic motion. A library containing technical data related to motors and gearboxes was created to be utilised in the optimisation algorithm. The method accelerates the time-consuming iterative process for obtaining optimum conceptual design solutions for a dynamic system and allows for easy modification of design parameters and constraints. It also makes the algorithm suitable for different types of dynamic system designs.

Design and optimisation of energy‐efficient PM‐assisted synchronous reluctance machines for electric vehicles

AbstractThe design and optimisation of a permanent magnet‐assisted synchronous reluctance (PMaSynR) traction machine is described to improve its energy efficiency over a selection of driving cycles, when installed on a four‐wheel‐drive electrically powered vehicle for urban use, with two on‐board powertrains. The driving cycle‐based optimisation is defined with the objective of minimising motor energy loss under strict size constraints, while maintaining the peak torque and restricting the torque ripple. The key design parameters that exert the most significant influence on the selected performance indicators are identified through a parametric sensitivity analysis. The optimisation brings a motor design that is characterised by an energy loss reduction of 8.2% over the WLTP Class 2 driving cycle and 11.7% over the NEDC and Artemis Urban driving cycles, at the price of a 4.7% peak torque reduction with respect to the baseline machine. Additional analysis, implemented outside the optimisation framework, revealed that different coil turn adjustments would reduce the energy loss along the considered driving cycles. However, under realistic size constraints, the optimal design solutions are the same.

Повышение технологичности и эксплуатационной надежности гидроразжимного соединения сваи с основанием морской стационарной платформы

Object and purpose of research. This paper discusses hydraulic-release couplings of pillars and substructures for fixed marine platforms. This topic is relevant because at some platforms hydraulic-release couplings contribute to crack initiation. The purpose of this study was to work out design solutions that would mitigate residual strains so as to preclude pillar cracking due to hydraulic release, thus making the pillars more durable. Achieving this purpose will make hydraulic release more suitable for routine operation, and will also make Russian manufacturers of fixed marine platforms more independent from Western patent holders of hydraulic release system designs. Subject matter and methods. Design solutions suggested in this study were tried out through finite-element simulation of hydraulic release process. Plastic straining of pillars was taken into account by means of a linear kinematic model of hardening. Main results. The study covered seven possible designs of hydraulic release units and yielded load diagrams for both plastic straining of pillar over the entire working cycle of hydraulic release (with indication of maximum accumulated plastic strain) and subsequent pillar pull-out from substructure. Conclusion. The study yielded an optimal design solution for hydraulic release joint that both reduces plastic straining of pillar and increases axial stiffness of the joint itself.

Effects of indoor environment factors on productivity of university workplaces: A structural equation model

How are the indoor environment factors affecting the work productivity of office users in university buildings? Statistical analyses were undertaken on data probing building usage and self-reported indoor environment quality (IEQ) perception from a survey of 157 postgraduate students and 89 staff members at a university in New Zealand. Results of the partial least squares structural equational modelling confirmed the positive correlation among the IEQ within an office, the wellbeing and comfort as well as three dimensions of work productivity. IEQ factors relating to aesthetics and views were found to have the strongest effect on wellbeing and comfort as well as productivity for postgraduate students, whereas factors related to spatial and cleanliness are the most important for staff members. For both cohorts, the wellbeing and comfort in the office have significant direct effects on contextual performance, which indirectly further affects office users’ ability in time management and task performance. The findings highlight the importance of the inclusion of design features that are productivity and wellbeing oriented across the building and the need for appropriate consultation with university office building users (e.g., students and staff) to achieve optimised design solutions.