Optimal Design Methods Research Articles

Solvent selection for chemical reactions toward optimal thermodynamic and kinetic performances: Group contribution and COSMO-based modeling

The chemical industry makes extensive use of solvents in both reaction and separation processes. The large number of existing and potentially new solvents calls for systematic methods for optimal solvent selection and design to reduce experimental efforts and accelerate process development in the early phase. There have been numerous contributions made towards the optimal selection and design of solvents as mass separating agents for various separation processes. In comparison, despite of the strong impact of solvents on chemical reactions by changing the reaction rate and/or shifting the chemical equilibrium, limited work on reaction solvent selection has been reported. Moreover, there is still a lack of insightful perspective article on model-based reaction solvent selection/design. In this work, we address this shortcoming by summarizing the state-of-the-art studies on reaction solvent selection/design using various computational methods, with a focus on group contribution and conductor-like screening model (COSMO)-based modeling approaches. Solvent selections for reactions integrated with up- and/or downstream process design, including the impact of catalyst and a group contribution extension to the COSMO models, are highlighted as potential future directions.

Multi-objective reliability optimization design of high-speed heavy-duty gears based on APCK-SORA model

For high-speed heavy-duty gears in operation is prone to high tooth surface temperature rise and thus produce tooth surface gluing leading to transmission failure and other adverse effects, but in the gear optimization design and little consideration of thermal transmission errors and thermal resonance and other factors, while the conventional multi-objective optimization design methods are difficult to achieve the optimum of each objective. Based on this, the paper proposes a gear multi-objective reliability optimisation design method based on the APCK-SORA model. The PC-Kriging model and the adaptive k-means clustering method are combined to construct an adaptive reliability analysis method (APCK for short), which is then integrated with the SORA optimisation algorithm. The objective function is the lightweight of gear pair, the maximum overlap degree and the maximum anti-glue strength; the basic parameters of the gear and the sensitivity parameters affecting the thermal deformation and thermal resonance of the gear are used as design variables; the amount of thermal deformation and thermal resonance, as well as the contact strength of the tooth face and the bending strength of the tooth root are used as constraints; the optimisation results show that: the mass of the gear is reduced by 0.13kg, the degree of overlap is increased by 0.016 and the coefficient of safety against galling Compared with other methods, the proposed method is more efficient than the other methods in meeting the multi-objective reliability design requirements of lightweighting, ensuring smoothness and anti-galling capability of high-speed heavy-duty gears.

OPTIMAL DESIGN OF INVOLUTE SPUR GEARS WITH INCREASED CONTACT RATIO: OBJECTIVE FUNCTION, VARIABLES PLANNING AND CONSTRAINTS

Reducing the mass and dimensions of involute spur gears is an actual task of modern mechanical engineering. One of the perspective ways to solve it is the use of gearing with an increased working tooth depth and profile contact ratio εα ≥ 2. The study is devoted to the development of optimal design methods for such gears. Optimality criteria is formulated as follows: the contact stresses in the pitch point must take a minimum value when all constructive, geometric, kinematic, and technological constraints are met, first, when the profile contact ratio εα ≥ 2 is ensured. Variables planning are defined. These are addendum coefficients of the basic racks tooth for pinion and wheel , ; profile angle of the basic rack α; addendum modification coefficient of the pinion x1. Formed a system of constraints for the variables planning: the main functional constraint of the minimum value of the profile contact ratio: εα ≥ 2; constraint for the addendum coefficients of the basic racks tooth for pinion and wheel , ; constraint for profile angle of the basic rack α; constraint for addendum modification coefficients x1, x2; absence of the cutter interference for tooth dedendum; absence of the sharpening for tooth addendum; absence of the mesh interference; ensuring the bending strength of pinion and wheel teeth. A method for solving the problem of optimal design is chosen. The method of probing the space of design parameters was chosen from all the variety. The points of the LPτ-sequence are used as test points. The method allows you to operate with a significant number of parameters – up to 51, provides a sufficiently large number of evenly distributed test points – up to 220. In further studies, it is planned developing of methods and algorithms for solving the problem. Also carry out test and verification calculations to confirm and evaluate the theoretical results. Keywords: spur gear, profile contact ratio, contact stress, optimal design, objective function, variables planning, constraints of the variables planning.

Globally optimal trial design and risk sharing arrangements are key to avoiding opportunity costs of delay and enabling equitable, feasible and effective global vaccine research and implementation in current or future pandemics.

Global vaccination in the face of pandemics such as COVID-19 and new variants is a race against time. Avoiding the opportunity costs of delay and the associated health, social, and downstream economic impacts is a challenge and an imperative. Failures to address the global challenges posed by COVID-19 have become increasingly evident as waves of vaccine-evading mutations have emerged, facilitated by unequal vaccination coverage and diminishing immunity against new variants worldwide. To address these challenges, societal decision-makers (governments) and industry manufacturer interests must be better aligned for rapid, globally optimal trial design, ideally with research coverage, implementation, and accessibility of effective vaccines across joint research, implementation, and distribution cycles to address pandemic evolution in real time. Value of information (VoI) methods for optimal global trial design and risk-sharing arrangements align the research, distribution, and implementation interests and efforts globally to meet head-on the imperative of avoiding opportunity costs of delay and enabling consistent global solutions with maximizing local and global net benefits. They uniquely enable feasible early adoption of the most promising strategies in real time while the best globally translatable evidence is collected and interests are aligned for global distribution and implementation. Furthermore, these methods are generally shown to be imperative for feasible, fast, and optimal solutions across joint research, reimbursement, and regulatory processes for current and future pandemics and other global existential threats. Establishing pathways for globally optimal trial designs, risk-sharing agreements, and efficient translation to practice is urgent on many fronts.

A Modified Quantum-Inspired Genetic Algorithm for Continuum Structural Topology Optimization

Topology optimization and quantum computing have evolved rapidly over the past three decades. Previous topological optimum design methods suffered from financial burden and mathematical complexity. To overcome these shortcomings, a modified quantum-inspired evolutionary algorithm-based topology optimization method is proposed. This nested approach combines the classic solid isotropic microstructure with the penalization method and the double chains quantum genetic algorithm to establish an integral topology optimization framework. The former is utilized to determine the search direction of design variable updating. Meanwhile, the latter ensures abundant search diversity. The validity and feasibility of the developed methodology are eventually demonstrated by several application examples. The results indicate that the proposed optimization framework is independent of initial values and can lead to optimized structures. In addition, it will be more appropriate and effective if this strategy is deployed on a quantum computer in the future.

A review of research on the impact of the classroom physical environment on schoolchildren's health

Students spend more than 70% of their time in the classroom, and the quality of the classroom environment has an important impact on the physical and mental health of students in the growing stage. Drawing on Scopus, China National Knowledge Infrastructure databases, this paper sorts and summarizes 173 research articles on the impact of the classroom environment on the physical and mental health of schoolchildren in the past 20 years. Based on the aspects of acoustic, light, thermal, and air quality, nine key indicators and their impact on classroom indoor environments and thus student health are identified (background noise level, reverberation time, useful daylight illuminance, indoor air temperature, relative humidity and air velocity, ventilation rate, CO2 and PM2.5 concentrations). Corresponding classroom optimization design methods and potential improvements are proposed. Compared with related studies of adults, it is found that adolescents are suitable for cooler indoor temperatures, while their sensitivity to daylight illuminance, noise, and PM2.5 concentrations is higher than that of adults.

Efficiency-oriented circuit parameter optimization of dual active bridge converter

The power carbon neutrality path is to build a new power system with new energy as the main body. Dual active bridge (DAB) converter is considered as the core topology of new power system mode due to its galvanic isolation, bi-directional power capability, and wide soft-switching range, which is responsible for inter-connection between DC buses of different voltage levels and various DC loads. However, the lack of fast and accurate quantitative circuit parameter optimization design methods in DAB converter affects the improvement of the full working domain efficiency. In this paper, a hierarchical filtering method considering the control parameter is proposed to avoid the full range exhaustive search, and the effectiveness and correctness of the method are verified experimentally. First layer circuit characteristics must fulfill output power and inductor current requirements. The second layer filters poor inductor RMS current and soft-switching parameters. The last layer filters out weak steady-state circuit characteristics and identifies optimal regions. The proposed method improves the efficiency while reducing the area of the circuit parameter region for calculating the loss function by 85% compared with the traditional full-scale search method based on the loss analysis model, thus improving the optimization speed. The optimal circuit parameter solving process provides a graphical representation of the relationship between DAB operating characteristics and the optimal parameter area, ensuring proper optimization. Besides, the idea of hierarchical filtering can be well applied to the optimal design of other converters, and better guide the industrialization of products. • Using hierarchical filtering method can speed up the design. • Visualization of parameters can ensure the correctness of optimization results. • The design of other converters can also use the hierarchical filtering method. • Optimal design of parameters can ensure the normal operation of the device and also improve the steady-state characteristics.

Experiment, simulation, optimization design, and damage detection of composite shell of hydrogen storage vessel-A review

The composite shell of composite high pressure hydrogen storage vessel (CHPHSV) is the main structure in bearing inner pressure. Its failure will lead to leakage or burst of CHPHSV, which will cause serious safety problem and economic losses. So the security of CHPHSV has always been a key and difficult problem in academia and industry, which restricts the large-scale application of hydrogen. In this paper, the failures of composite shell of type III, type IV, and type V vessels are reviewed in experiment study, simulation method, optimization design, and damage detection, focusing on the burst modes (safe or unsafe), the influence of hydrogen-thermo-stress field, and the epistemic uncertainty. Firstly, the burst modes, failure behavior, test method, and influencing factors are summarized in the experiment study, and experiment for type V composite pressure vessel is discussed. Secondly, the simulation method is reviewed in the aspect of first ply failure (FPF) analysis and last ply failure (LPF) analysis. The damage evolution of safe burst mode and unsafe burst mode is summarized. Besides, the influence of hydrogen-thermo-stress field and the uncertainty characteristic are also reviewed. Moreover, simulations of micro-crack and permeability for type V composite pressure vessels are summarized. Then, the optimization design methods based on deterministic parameters and uncertain parameters are reviewed. Finally, the damage detection methods of the composite shell of CHPHSV are summarized. The experiment, numerical simulation, and optimization are important for design of the composite vessel, and the damage detection can significantly reduce the degree of uncertainty and maintenance safety. In the future research, precise model considering multiple damage modes, hydrogen-thermo-stress field effect should be established for simulation of safe and unsafe burst mode. Uncertain quantization should be studied for burst pressure with combination of stochastic uncertainty and epistemic uncertainty. Besides, the robust design method based on the reliability of CHPHSV considering the epistemic uncertainty of design parameters should be established for a larger safety margin.

OPTIMIZATION OF CUTTING MODES ON HEAVY MACHINES

The work is devoted to improvement of the design theory and development on this basis of adaptive hydrostatic supports of new generation, as well as development of methods for optimal design of spindle assemblies and guides with such supports. It is established that the use of fluid friction modes in heavily loaded nodes is very relevant for heavy numerically controlled precision machine tools. Hydrostatic spindle bearings are used in heavy lathes, in which the required accuracy of rotation is not provided by rolling bearings. An adaptive system for controlling the pressure in the pockets of hydrostatic supports and the tensioning force of the positioning drive has been developed. The system makes it possible to adjust the transfer function and exclude the possibility of oscillations by rather simple means. By means of the system the accuracy and productivity of machining on metal-cutting machines of different technological purposes is significantly increased. The reliability of the supports is increased, since the throttle elements are in motion during operation, which prevents the throttle gap from becoming overgrown. Stiffness and load-bearing capacity of the lubricant layer are increased. Debugging work on setting the working pressure in the support pockets is eliminated. The mechatronic system of adaptive control of pressure in the pockets of hydrostatic spindle assembly with increased accuracy is developed. Adaptive regulators of support power supply systems with spindle position feedback have been developed. A new design of hydrostatic bearing sleeve with built-in capacitive clearance sensors is developed

Wind Turbine Design and Assessment

This project aims to design a wind turbine for the bam area of Zhangjiakou City, which has a relative high wind speed because of the good development prospect of China’s wind power. Based on the detailed investigation of wind speed and direction in the bam area of Zhangjiakou, the project designs a wind turbine that can produce as much energy as possible. The turbine with a hub height of 70 m, hub radius 1 m and radius 40 m is designed by using optimal blade design methods. Finally, the performance of wind turbine can be simulated by using the theory of blade element momentum and the corresponding annual energy yield can be calculated.

Optimal Design and Verification of Informal Learning Spaces (ILS) in Chinese Universities Based on Visual Perception Analysis

As the focus on higher education in China gradually shifts from rapid development to an emphasis on quality, the need for campus environments to become facilitators of education has gained increasing attention. The accelerated development of information technology has also led to tremendous changes in both teaching and learning methods, with informal learning taking on an increasingly important role. Furthermore, the development of human sensing technology, especially visual perception technology, has brought in new opportunities for the research and optimization of informal learning spaces (ILSs) in universities. This paper focuses on the ILS in Chinese universities by exploring optimal design approaches based on visual perception analysis. Through research and field investigation, this paper proposes revised theoretical research of classifications and spatial elements of ILS in universities more applicable to the architectural study of space. This paper also explores practical optimal design methods with two case studies and makes experiments with wearable eye trackers to study the users’ perception in these spaces before and after optimization. The optimal design is made from the aspects of physical space, facilities, and environment. Visual perception experiments and quantitative analysis were used to obtain a higher level of experimental accuracy than the previous studies and thus to study the real feeling of users in spaces. By these means, the effect of the optimized design was verified and the relation between users’ perceptions and the spatial environments was explored for further improvements to optimal design methods. This article can provide theoretical and practical references for campus space optimization research and design, especially for ILS on university campuses.

Solution of the optimization problem for the purpose of designing a lattice polymer composite structure with the outer skin

In recent years, the urgency of the problem of launch vehicles load-bearing elements optimal design has continued to grow. One of the widespread structural designs is an anisogrid lattice structure made of polymer composite materials. Such structures are mass-produced and used as load-bearing bodies of space vehicles or fuselage compartments of atmospheric aircraft of advanced structural design. Until now, the weight and parameters of the skins used in products of rocket and space equipment have not been considered when solving optimal design problems, and the design problem has been reduced to optimizing lattice structures without skin. At the same time, the very use of skins for both atmospheric aircraft and load-bearing elements for space applications is a fairly common practice. However, not considering the availability of skin when designing a lattice load-bearing shell can lead to a significant increase in the mass of the structure with skin when applicable. The paper presents a method for the optimal design of lattice structures without ring ribs, but with the metal skin available, which can significantly reduce the weight of such structures, increasing the mass efficiency of products made of polymer composite materials used in aircraft. A confirmation of the results obtained with the help of an analytical solution and the results of a numerical experiment, obtained by modeling using the finite element method, is given. It is expected that the use of the proposed approach by considering the contribution of the skin response can lead to mass saving of the shell anisogrid structure up to 30 % compared with the methods of optimal design of lattice anisogrid structures currently used without considering the availability of skin in the design of the product.

Methods and applications of on-chip beam splitting: A review

The construction of large-scale integrated photonic circuit cannot be separated from the important role played by silicon-based optoelectronic devices. As a basic and important link in on-chip photon propagation, beam splitting is of great significance for the efficient utilization of sources and the compact integration of optoelectronic devices. It is widely used in power splitting, polarization separation, wavelength division multiplexing and other scenarios. This paper reviews the on-chip beam splitting methods in recent years, which are mainly divided into the following categories: y-branch, multimode interference coupling, directional coupling, and inverse design. This paper introduces their research status, including optimization design methods, functions and applications in large-scale quantum chips and optoelectronic hybrid integration, looking forward to providing a reference for the further research of beam splitting methods and the wide application of beam splitters in the frontier field in the future.

Analysis and Design of a Nonisolated DC Transformer With Fault Current Limiting Capability

The dc–dc converter, also termed as dc transformer, plays an important role in the future dc grids. It is used to interconnect network segments or lines with different voltage levels. A nonisolated modular multilevel dc–dc converter is presented in this article, which can realize bidirectional power regulation and dc fault current limiting. The control strategy is simplified and the current stresses are decreased due to the employment of autotransformers. The nonisolated structure can reduce the requirements of autotransformers, because only part of the transmitted power flowing though the autotransformers. The operation principle and control strategy of this converter are illustrated in detail. The analyzes of power transmission, submodule (SM) capacitor voltage ripple, the optimal configuration, and the efficiency of this converter are also provided. The optimal design methods of the dc transformer are proposed to reduce the costs and power losses according to the analysis results. Simulations performed in power systems computer aided design/electromagnetic transients including DC (PSCAD/EMTDC) and experiments based on a down-scaled prototype verify the operation principle, control strategy, and theoretical analysis. The simulation results and experiment results show the performances of the converter under steady state, power regulation, and fault conditions.

Optimal Design and Operation of Dual-Ejector PEMFC Hydrogen Supply and Circulation System

A proton exchange membrane fuel cell (PEMFC) system requires an adequate hydrogen supply and circulation to achieve its expected performance and operating life. An ejector-based hydrogen circulation system can reduce the operating and maintenance costs, noise, and parasitic power consumption by eliminating the recirculation pump. However, the ejector’s hydrogen entrainment capability, restricted by its geometric parameters and flow control variability, can only operate properly within a relatively narrow range of fuel cell output power. This research introduced the optimal design and operation control methods of a dual-ejector hydrogen supply/circulation system to support the full range of PEMFC system operations. The technique was demonstrated on a 70 kW PEMFC stack with an effective hydrogen entrainment ratio covering 8% to 100% of its output power. The optimal geometry design ensured each ejector covered a specific output power range with maximized entrainment capability. Furthermore, the optimal control of hydrogen flow and the two ejectors’ opening and closing times minimized the anode gas pressure fluctuation and reduced the potential harm to the PEMFC’s operation life. The optimizations were based on dedicated computational fluid dynamics (CFD) and system dynamics models and simulations. Bench tests of the resulting ejector-based hydrogen supply/circulation system verified the simulation and optimization results.

The influence of load modes obtained by the topological optimization method on power circuits of mining dump truck load-bearing units

Introduction (statement of the problem and relevance). Reducing the power elements mass of mining dump trucks to increase their load capacity without losing strength indicators is an important task. When creating modern models of heavy-loaded mining trucks, special attention should be paid both to the design of load-bearing elements of the system and passive safety structures, taking into account their joint work. The use of topological optimization methods at the early stages of design has become widespread in the creation of highly loaded elements of wheeled vehicles.The purpose of the research was to study the effect of loading conditions on the power circuits of loadbearing systems and protective structures, as well as to formulate recommendations for creating the structures at the initial design stage for improving the strength and safety of mining trucks by means of the topological optimization method based on the finite element method and to work out the stiffness algorithm.Methodology and research methods. The article presents a dynamic mathematical model of a wheeled vehicle created in the program for modeling the rigid bodies dynamics for determining loads. The power circuits of the carrier system and the protective structure were obtained with the help of the topological optimization method based on the finite element method. The object of the study was a mining truck with a gross weight of 220 tons. The subject of the research was to study the methods of optimal design and use of the vehicles load-bearing structures taking into account operating conditions.Scientific novelty and results. The influence of load modes on the power circuits of the carrier system and the protective structures has been revealed. Recommendations were given for the choice of load modes at the early stages of designing mining dump trucks for topological optimization. The power circuits of the carrier system and the protective structures were presented. Conclusions were drawn concerning the influence of load modes on the power structures of load-bearing elements.Practical significance. The results obtained can be used to create highly loaded elements of mining trucks.

Test of Ultimate Bearing Capacity of Building Concrete Structures in Earthquake Area Based on Virtual Reality

In order to solve the poor matching ability between concrete structures of traditional architectural space optimization design methods, it leads to the problem of low space optimization ratio, so based on virtual reality technology, the author proposes a new method for optimizing the space of concrete structure buildings. Using virtual reality technology to improve the basic structure of building space, reorganize the form through the design space, and optimize the design of the concrete structure building space function; based on the test model of virtual reality technology, design the matching method of concrete structure, increase the proportion of building space optimization, and adopt linear buckling method, geometric nonlinear method, and double nonlinear analysis method; the ultimate bearing capacity of steel structures of residential buildings in earthquake areas is tested. Experimental results show that for the simple structure building space, the average optimization ratios are 97.17% and 96.71%, respectively; for the complex structure building space, under the proposed optimization design, the average optimization ratio is maintained at 94.34%, and the error between the stress prediction value of the finite element model and the axial stress obtained by testing is less than 6%. Compared with the traditional space optimization design, in the proposed space optimization design method, the proportion of building space optimization is higher; it can be seen that the virtual reality technology has a better matching effect on the concrete structure, and the accuracy of the ultimate bearing capacity value obtained by prediction is high.

A review on the mechanical property evaluation and optimization design of fabric rubber composite structure

Fabric rubber composite structure is a composite structure with rubber as the matrix and fiber as the reinforcement, which is widely used in high-end equipment due to its excellent mechanical property and sealing performance. The mechanical property, multiscale analysis techniques and optimization design methods of fabric rubber composite structure in a complex service environment are the focuses of current research and application fields. This article will systematically review the research progresses in the mechanical property evaluation and optimization design of fabric rubber composite structure in recent years from the aspects of theory, experiment, simulation, etc. This will deepen the understanding of the design concepts of fabric rubber composite structure. It has important scientific guiding significance for the innovative design of fabric rubber composite structure.

Novel Optimization Design Methods of Highly Loaded Compressor Cascades Considering Endwall Effect.

The endwall effect has a great impact on the aerodynamic performance of compressor blades. Based on three conventional near-endwall blade modeling methods of bowed blade, endbend blade and leading-edge strake blade (LESB), two combined optimization design methods of highly loaded blades have been developed considering the endwall effect in the current study, i.e., the bowed blade combined with the LESB (bowed LESB blade) and the endbend blade combined with the LESB (endbend LESB blade). Optimization designs were conducted for a compressor cascade with low solidity by using the two combined modeling methods and the three conventional modeling methods, and the optimization results were compared and analyzed in detail. The results showed that the five optimization modelling methods could all improve the performance for the original cascade, and the optimized cascade with the bowed LESB modeling method has the best aerodynamic performance. The total pressure loss of the optimal bowed LESB cascade was only 40.3% of that in the original cascade while reducing the solidity of the original cascade from 1.53 to 1.25 and keeping the static pressure rise and diffusion factor at the same level as the original one. Among the optimal cascades, the radial migration height of the low-energy fluid and the corresponding vortex have great effects on the aerodynamic performance, and the optimal bowed LESB cascade is superior to the other optimal cascades in this aspect.

Optimized Rod Size Design of Denim Fabric Grinding Robot Based on Improved Cuckoo Search Algorithm

Background: Dexterity is an important index for evaluating the motion performance of a robot. The size of the robot connecting rods directly affects the performance of flexibility. Objective: The purpose of this study is to provide an overview of optimal design methods from many pieces of literature and patents, and propose a new optimal design method for ensuring the robot completes its tasks flexibly and efficiently under workspace constraints. Methods: The kinematics and working space of the robot are analyzed to determine the range of motion of each joint. Then, a dexterity index is established based on the mean value of the global spatial condition number. Finally, an improved cuckoo algorithm is proposed, which changes the step size control factor with the number of iterations. Taking the dexterity index as the objective optimization function and the working radius as the constraint condition, the improved cuckoo search algorithm is used to optimize the size of the robot rod. Results: The improved cuckoo algorithm and proposed rod size optimized method are fully evaluated by experiments and comparative studies. The optimization design process shows that the proposed method has better solution accuracy and faster convergence speed. The optimized design results show that the robot's dexterity index has increased by 26.1%. Conclusion: The proposed method has better solution accuracy and faster convergence speed. The method was suitable for optimizing the rod parameters of the robot, and it was very meaningful to improve the motion performance of the robot.