Optimum Design Research Articles

Investigation of lift enhancement through circulation control for distributed propulsion

To meet the design requirements for high lift airfoils, an optimization design platform was established using the SNOPT (Sparse Nonlinear Optimizer) method. Two airfoils were designed to achieve both low-speed takeoff/landing and high-speed cruise performance. A comparison between the self-designed airfoils and mature airfoils was carried out at different operating conditions, and the airfoil that met the target requirements was selected. Subsequently, an integrated design of ducted-fan/wing was conducted to study the effect of integrated constraints on the lift augmentation of the wing with the action of the propeller. The results showed that under the integrated layout, the ducted-fan significantly changed the flow velocity field from the front of the inlet and the tail jet, which to some extent changed the upper surface circulation of the wing. Compared with the pure wing, the maximum lift increase was up to 332 %.

Numerical investigation on the flow resistance characteristics of balance block in the rotary compressor

With the increasing demand for energy saving, the air conditioner with variable frequency becomes the mainstream of the market, which leads to a high requirement for the dynamic balance characteristics of the rotary compressor at variable speed conditions. The balance block is the key part in the eccentric shaft system to balance the rotational inertia force brought by the eccentric wheel, and its flow resistance during rotating process has a large impact on the power consumption. In this paper, CFD simulations will be carried out to study the flow characteristics of several different compressor balance blocks and the results can provide reference for the optimization design of the balance block in the rotary compressor.

Electromagnetic Characteristics and Microwave Absorbing Properties of a Novel Stainless Steel Powder

In order to solve the problem of insufficient oxidation resistance and corrosion resistance of magnetic metal absorbent represented by carbonyl iron powder, a wave absorbing composite material which consists of different filling mass proportions of the atomized electrolytic stainless steel powder and paraffin wax is investigated. The electromagnetic (EM) characteristics and absorbing performance of the proposed composite material were tested with Agilent N5234A vector network analyzer in a frequency range of 2–18GHz. The experimental results show that the real and imaginary parts of the dielectric permittivity of stainless steel powder/paraffin composites will increase with the filling mass fraction in the test frequency band, while the real part of the permeability [Formula: see text] decreases with the increase of the mass fraction, and the imaginary part [Formula: see text] increases with the increase of the mass fraction. At a thickness of 3 mm, with the filling mass fraction increasing from 20 wt.% to 60 wt.%, the peak frequency of reflection loss (RL) moves to low frequency from 17.92 GHz to 16 GHz. Meanwhile, the minimum reflection loss (RL[Formula: see text]) also shows a downward trend, and the RL[Formula: see text] value with a filling mass fraction of 60 wt.% is −8.93[Formula: see text]dB. It can be seen that stainless steel powder shows good microwave absorbing performance, and it has excellent anti-oxidation, and anti-corrosion properties. Based on the excellent performance of stainless steel powder, its absorption performance is expected to be further improved through multi-layer optimization design, so as to meet the needs of electromagnetic protection in harsh environments.

Curvature generation based on weight-updated boosting using shoe last point-cloud measurements

Lasts are foot-shaped forms made of plastic, wood, aluminum, or 3D-printed plastic. The last of a shoe determines not only its shape and style but also how well it fits and protects the foot. A weight-updated boosting-based ensemble learning (WUBEL) algorithm is presented in this paper to extract critical features (points) from plantar pressure imaging to optimize the shoe's last surface to satisfy a comfortable shoe's last surface optimization design. An enhanced last design is constructed from the foot measurement data of the bottom surface of the base last, the critical control lines (points) of the shoe's last body, and the running-in degree of the pressure-sensitive area lattice data. Using a Likert scale (LS) and relevant evaluation indicators, we conducted an experimental evaluation and comparative study of our enhanced last design. With a point-cloud dataset, the proposed method performs highly effectively in constructing shoes, which will help diabetes patients find comfortable and customized shoes.

Shape optimization of sound barriers using an isogeometric meshless method

The sound barrier is an important means to reduce noise caused by traveling vehicles on roads or railways. Structural design and optimization of the sound barrier can effectively reduce the use of materials and improve the noise reduction effect. In this paper, a new isogeometric singular boundary method is proposed and applied to the shape optimization of sound barriers. The geometric structure is accurately represented by using non-uniform rational B-splines. The acoustic shape sensitivity of the control points was calculated using the direct differentiation method and the adjoint variable method. After that, the method of moving asymptotes is adopted as an optimizer to search for the optimal layout of the design objective. In the numerical procedure, the shoelace formula is introduced to calculate the area of the closed structure, which only uses the discrete node information on the boundary. The proposed approach completely avoids the mesh division in the finite element method as well as the singular integral calculation in the boundary element method. More importantly, it can be seamlessly connected with the computer-aided design system for the subsequent treatment by engineers. Three numerical examples are provided to illustrate the accuracy and effectiveness of the proposed isogeometric method. This work provides a simple and effective way for the structural optimization design of sound barriers.

Experimental study on multi-condition of axial flow pump in the whole flow field based on piv test

To study the internal flow characteristics of the axial flow pump in the whole flow field under different flow conditions, particle image velocimetry technology was used to measure the steady and unsteady flow fields of the axial flow pump, analyzed the velocity field distribution at the impeller inlet, impeller inner, guide vane inner, and guide vane outlet of the pump under different flow conditions (Q/Q des=0.8, 1, 1.1). Through the test and data analysis: under the three flow conditions, the velocity distribution trend of the impeller inlet of the axial flow pump is consistent and basically along the axis direction; there is a large velocity gradient in the flow field inside the impeller, and there is a significant acceleration near the hub trend, and there is a high-speed concentrated area; the velocity distribution trend in the guide vane is basically the same, and the fluid velocity changes more uniformly at the rated flow rate, and the flow tends to be more stable; a local high-speed area appears at the outer edge of the guide vane outlet, but in the second half The flow velocity in the pipeline is relatively uniform. The test results can provide a reference for the internal flow characteristics and performance optimization design of the axial flow pump.

Multi-objective optimization design of aerodynamic and infrared characteristics of multi-stream serpentine nozzle

A multi-objective optimization design of multi-stream serpentine nozzle was carried out to improve the aerodynamic performance and reduce the infrared radiation signal. A numerical simulation was carried out to investigate the effects of nozzle pressure ratio (NPR), Aspect ratio (AR) and Ratio of length and diameter (L/D). Computational fluid dynamics (CFD) simulation was employed to study the aerodynamic performance of the multi-stream serpentine nozzle, and the narrow-band method with discrete transfer method were used to calculate its infrared radiation intensity distribution characteristics. A 3-factor, 21-level orthogonal table was designed based on the orthogonal experimental method, and multi-stream serpentine nozzle with different geometrical parameter and operating conditions were designed to obtain the aerodynamic performance and infrared radiation intensity data of each experimental sample point. Radial Basis Function (RBF) neural network and Multi-Objective Particle Swarm Optimization algorithm were used to optimize the geometry and operating conditions with better aerodynamic performance and weaker infrared signal. The result shows that the Pareto solutions obtained by the optimization have good accuracy compared with the numerical simulation results, with an aerodynamic performance error of 0.02% and an infrared radiation intensity error of 0.24%.

An Efficient Optimization Design Framework for Low-Resistance Shape of Bionic Amphibious Robot

An Efficient Optimization Design Framework for Low-Resistance Shape of Bionic Amphibious Robot

Drive Layout Configuration Strategy and Scale Optimization Design of Multi-Drive Mode Parallel Mechanism

Abstract Aiming at the inherent defects of single-drive mode parallel mechanisms, such as small good workspace and many singular configurations, a new multi-drive mode parallel mechanism is proposed from the perspective of driving innovation. Taking the planar 6R parallel mechanism as an example, the driving layout configuration strategy and scale optimization design are studied. First, the potential driving layout of the mechanism is analyzed, and the inverse kinematics model of the mechanism is established. Then, based on the motion/force transmission index, the singular space and good transmission workspace of the mechanism are identified, and the mechanism-driven layout configuration strategy is formulated to complete the performance comparison analysis. Finally, based on the performance map method, the scale optimization design of the mechanism is carried out, the prototype is developed and manufactured, and the experimental verification is carried out. The research results show that the multi-drive mode parallel mechanism can improve its kinematic performance without changing the topological structure and scale parameters of the mechanism.

Parameters collaborative optimization design and innovation verification approach for fuel cell distributed drive electric tractor

Fuel cell distributed drive electric tractors (FCDET) are one of the necessary means to achieve truly green agriculture. However, low traction efficiency, poor control coordination, and excessive energy consumption are the main reasons hindering the industrialization of FCDET. This paper proposed a parametric collaborative optimization design method and innovative verification system that considers the drive system and energy system. Based on the tractor plowing operating conditions, a 7-DOF coupled dynamics model of the distributed drive system and a tire-soil interaction model were established, and the key component selection and parameter matching were completed. On the drive system optimization level, the front and rear wheelside transmission ratios are optimized based on a multi-island genetic algorithm (MIGA). On the energy system optimization level, the globally optimal power distribution ratio is found based on the dynamic programming algorithm (DP). A complete experimental prototype verification system is constructed based on the MATLAB/Simulink-NI PXI joint simulation platform, physical prototype test bench, and real vehicle multi-index test platform. The results show that the average efficiencies of the optimized drive and energy system are increased by 0.38 % and 3.82 %, the total energy consumption (total hydrogen consumption) is reduced by 25.40 % and 15.39 %, respectively. The maximum fault-free operating time is 5.5h, the average traction power is 21.07 kW, and the average traction force is 10610 N in the all-wheel drive mode. The experimental results fully demonstrate that the electric tractor with the fuel cell distributed drive system as the core can meet the verification of multiple indicators. This study can provide a new theoretical basis and technical verification method for the optimal design and system control of fuel cell distributed drive electric tractors.

A generalized Bayesian optimal interval design for dose optimization in immunotherapy.

For novel immuno-oncology therapies, the primary purpose of a dose-finding trial is to identify an optimal dose (OD), defined as the tolerable dose having adequate efficacy and immune response under the unpredictable dose-outcome (toxicity, efficacy, and immune response) relationships. In addition, the multiple low or moderate-grade toxicities rather than dose-limiting toxicities (DLTs) and multiple levels of efficacy should be evaluated differently in dose-finding to determine true OD for developing novel immuno-oncology therapies. We proposed a generalized Bayesian optimal interval design for immunotherapy, simultaneously considering efficacy and toxicity grades and immune response outcomes. The proposed design, named gBOIN-ETI design, is model-assisted and easy to implement to develop immunotherapy efficiently. The operating characteristics of the gBOIN-ETI are compared with other dose-finding trial designs in oncology by simulation across various realistic settings. Our simulations show that the gBOIN-ETI design could outperform the other available approaches in terms of both the percentage of correct OD selection and the average number of patients allocated to the OD across various realistic trial settings.

Enhancing the efficiency and functionality of xylanase from Bacillus sp. RTS11: Optimization, purification, characterization, and prospects in kraft pulp bleaching.

Bacillus sp. RTS11, a xylanolytic strain, was isolated from the Algerian desert rocks. Genetic analysis revealed a remarkable 98.69% similarity to Bacillus pumilus. We harnessed optimization techniques, including Plackett-Burman screening and Box-Behnken optimization design, to amplify xylanase production and activity. The outcome of these efforts was an optimized medium that yielded an impressive xylanase production titer of 448.89 U, a threefold increase compared to the non-optimized medium (146 U). The Purification of xylanase was achieved through the three-phase partitioning technique, employing t-butanol and various chromatographic methods. Notably, anion exchange chromatography led to isolating a highly pure enzyme with a molecular weight of 60 kDa. The xylanase exhibited its peak activity at a temperature of 60°C and a pH of 9.0. When applied to pulp pretreatment, 20 U/g of xylanase demonstrated a substantial increase in the release of phenolic and chromophore compounds while reducing sugar content in the pulp. Furthermore, this versatile xylanase shows its ability to efficiently hydrolyze a variety of agro-industrial residues, including wheat bran, corn and grape waste, wheat straw, and sugarcane bagasse. These findings underscore the significant potential of this xylanase enzyme in biobleaching processes and the utilization of agro-industrial waste, opening up exciting avenues for sustainable and environmentally friendly industrial applications.

Optimization design and mechanical properties of multi-component ecological gelling materials

Replacing cement clinker by industrial by-products is important for their safe utilization and cost reduction. This study focused on multi-component ecological gelling material mainly consisting of granulated blast furnace slag (GGBS) powder with added fly ash, calcium carbide slag, phosphogypsum, and about 20% of PII cement. By means of compressive strength, mortar fluidity, leaching behavior, XRD, FTIR, TG and SEM, the effects of such key indices as the water-binder ratio and contents of cement, fly ash, calcium carbide slag, and GGBS on the working performance and mechanical properties of the proposed material were studied and discussed in detail. The best mechanical properties, with a 28 MPa strength reached in 7 days, were obtained at a water-binder ratio of 0.5, fly ash-to-GGBS ratio of 1:2, phosphogypsum-to-calcium carbide slag ratio of 1:2, and a 20% cement content. The Grey Relation Analysis (GRA) was used to analyze the influence of each component on the 3 d, 7 d, and 28 d strength, ranking them in the decreasing order as follows: GGBS, fly ash, cement, calcium carbide slag, and phosphogypsum. By combining the Grey Relation Analysis (GRA) with the experiment, the analysis results are more rigorous and the theory and experiment are combined. The results obtained are considered instrumental in optimizing multi-component ecological gelling materials for practical applications.

Multi-objective topology optimization for thermo-elastic systems based on periodic constraints

Thermo-elastic systems have a wide range of applications in various engineering fields. Traditional single-objective topology optimization (TO) design of thermos-elastic structures is difficult to achieve the combined optimum of multiple properties, and the non-periodic TO design of results are complex and difficult to fabricate. This paper introduces a multi-objective TO formulation based on density for designing thermo-elastic structures with periodic constraints, aiming to overcome the aforementioned issues. This paper assesses two competing weighted objective functions, the first function corresponds to structural and thermal compliance, while the second pertains to regional temperature and global stress. To solve the optimization issue, we utilize the p-norm function with a modified coefficient for evaluating the maximum temperature and stress values. Additionally, the adjoint variable method is employed to evaluate the sensitivity of various objectives, while the method of moving asymptotes (MMA) is used to update the design variables. Then the influence of different weight coefficients and subregion numbers regarding thermos-elastic coupled analysis is demonstrated through numerical examples. The results show that the complexity of the subregion features decreases as the number of subregions increases, and that changing both the number of subregions and the weighting coefficients results in changes in the overall structural performance. Finally, the geometric model is reconstructed using the TO results, and the structural performance is validated through the simulation of the reconstructed model. The results indicate that the TO results obtained by the method of this paper have predefined performance.

Numerical simulation study of impact of polydispersity on biomass pyrolysis in draft-tube spouted reactor with fountain confiner

During biomass pyrolysis within spouted reactor, particles exhibit behavior characterized by polydispersity. To explore the impact of polydispersity of bed materials on the biomass pyrolysis, the multiphase particle-in-cell model is constructed to simulate such process. The focus of the study is examining the impact of size distribution of solid materials and the presence of a draft tube on the particle-level properties. The results show that the yields of Gas1 and tar during the first pyrolysis increase about 13.1 % and 14.8 %, respectively, as the PSD width of sand increase from 0.1 to 0.7. In addition, the influence of the draft tube is primarily centered on enhancing interphase interactions rather than pyrolysis yields when a fountain confiner is applied. Fine particles mainly distribute along the interphase of annulus and its vicinity while coarse particles mainly accumulate along the interphase of annulus and spout. Expanding the PSD widths of bed materials from 0.1 to 0.7 results in an approximate temperature increase of 10 K in the floating biomass. The variation of particle slip velocity and heat transfer coefficient exhibits similar trend, mainly due to their interrelation in convective heat transfer. These findings hold valuable insights that can guide optimization design and parameter selection in the conical fountain confined spouted bed reactors.

Optimization Design of Interbody Fusion Cage withDifferent Bone Densities Printed in 3D

Based on the original data of cervical spine, the models of cervical C6 and C7 segments were reconstructed through medical image processing and reverse modeling operations, then the models were assembled to obtain the basic data of interbody fusion cage. According to the basic data, the structures of rectangular porous, gradient porous and octahedral porous interbody fusion cages were established respectively. Maximum force on the adult male neck was applied to the fusion device, and the stress, strain and maximum deformation of the fusion device were solved by finite element analysis. The elastic modulus decrease of the design, and the rectangular porosity structures with different porosity were analyzed and optimized. The results showed that the elastic modulus of the fusion cage with three structures decreased in varying degrees, and the porosity of the interbody fusion cage with rectangular structure was about 60%, which was the most decreased elastic modulus.

Multi-Objective Optimization Design of Cycloid-Pin Gears Based on RV Reducer Precision Transmission Performance

This paper aims to realize multi-objective optimization of cycloid-pin gears to improve the positioning accuracy and load-carrying capacity of the rotary vector (RV) reducer, via the consideration of backlash, transmission error, and torsional stiffness. Initially, the analytical models of the RV transmission backlash and transmission error are developed by using both purely geometrical and equivalent model methods individually. Based on the generalized Hooke’s law, a torsion angle model is established to characterize the torsional stiffness of the system, utilizing methods such as Hertzian contact theory and bearing stiffness models. Subsequently, employing the Monte Carlo method, extremum method, and quality loss function, mapping objective functions for dimensional accuracy (tolerance) and transmission performance (backlash, transmission error, and torsional stiffness) are constructed. The geometry dimensions, dimensional accuracy, and modification of the cycloid-pin gear are considered as design variables to create a multi-objective optimization model. The improved Parallel Adaptive Genetic Algorithm using Deferential Evolution (PAGA-DE) is used for multi-objective solutions. Through example calculations, the impact of cycloid-pin gear parameters on transmission performance before and after optimization is determined. The reliability of backlash after optimization within 1.5′ reaches 99.99%, showing an increase of 8.24%. The reliability of transmission error within 1′ reaches 98.52%, demonstrating an increase of 1.35%. The torsional angle is reduced by 8.9% before optimization. The results indicate that the proposed multi-objective optimization design method for cycloid-pin gears can achieve the goal of improving the transmission performance of the RV reducer.

A Comprehensive Multi-Strategy Enhanced Biogeography-Based Optimization Algorithm for High-Dimensional Optimization and Engineering Design Problems

The biogeography-based optimization (BBO) algorithm is known for its simplicity and low computational overhead, but it often struggles with falling into local optima and slow convergence speed. Against this background, this work presents a multi-strategy enhanced BBO variant, named MSBBO. Firstly, the example chasing strategy is proposed to eliminate the destruction of the inferior solutions to superior solutions. Secondly, the heuristic crossover strategy is designed to enhance the search ability of the population. Finally, the prey search–attack strategy is used to balance the exploration and exploitation. To verify the performance of MSBBO, we compare it with standard BBO, seven BBO variants (PRBBO, BBOSB, HGBBO, FABBO, BLEHO, MPBBO and BBOIMAM) and seven meta-heuristic algorithms (GWO, WOA, SSA, ChOA, MPA, GJO and BWO) on multiple dimensions of 24 benchmark functions. It concludes that MSBBO significantly outperforms all competitors both on convergence accuracy, speed and stability, and MSBBO basically converges to the same results on 10,000 dimensions as on 1000 dimensions. Further, MSBBO is applied to six real-world engineering design problems. The experimental results show that our work is still more competitive than other latest optimization techniques (COA, EDO, OMA, SHO and SCSO) on constrained optimization problems.

Preparation, characterization and composition optimization design of laser powder bed fusion continuously graded Invar36/316L stainless steel alloys

It is of great significance for designing different material compositions and batch experimental research via using additive manufacturing. In this work, Invar36 and 316L stainless steel (SS) are used as raw materials, and a specially designed powder distribution system in a laser powder bed fusion (LPBF) equipment is used to prepare continuous gradient alloys (CGAs) of Invar36/316L SS. The effects of microstructure and properties variations when the ratio of two compositions of Invar36 and 316L SS are systematically studied. It is found that the grain size and morphology of the melt pool would vary with the composition, but there is no significant difference in the phase distribution. In addition, localized areas of CGAs show similar or even better mechanical properties, thermal expansion properties, or corrosion resistance than the two materials themselves. When the percentage of Invar36 content is 70% - 80%, the microstructure and grain distribution of the samples are relatively uniform, and the tensile strength and corrosion resistance of the material are greatly improved, while the coefficient of thermal expansion does not increase significantly. The results of this work provide a practical path for the composition design and high throughput experiments of multiple materials.

Integrated Design of Axial Slot Casing Treatment and Blades in a Low-Speed Single Stage Axial Compressor

Abstract Casing treatment has been used to enhance the stability of axial-flow compressor by extending the stall margin; it also induces strong interaction with compressor blades, as demonstrated in the open literature. Revealing the mechanism of this interaction is a key to fully exploit the potential of the stability-enhancing capability of casing treatment without efficiency penalty. For this purpose, an integrated optimization design of rotor and axial slot casing treatment is implemented for a low-speed axial-flow compressor, and the stall margin is increased by 10.89% without penalty on the peak efficiency. Through detailed analysis, two important driving factors for the improvement of stall margin are illustrated: the suction effect that decreases the axial momentum of tip leakage flow, and the injection effect that increases the axial momentum of main flow. Meanwhile, it is found that the combination of forward-deflection axial slot casing treatment and forward-sweep rotor can maximize the enhancement of the momentum exchange, thereby adequately reducing the blockage region induced by tip leakage flow. More specially, the stator is then redesigned based on the matching mechanism between the stator and rotor with axial slot casing treatment in a stage. This redesign can considerably reduce entropy generation and flow separation in the passage and achieve an improvement of 0.87% in efficiency. The results hence demonstrate the superiority of integrated design of axial slot casing treatment and blades in improving both stall margin and efficiency.