Optimal Parameter Design Research Articles

Optimal design of GaN HEMT based high efficiency LLC converter

LLC converter has the advantages of large range voltage regulation ability, zero voltage switch (ZVS), magnetic isolation and is prevalent in data center power supply. As the increasing of power consumption in data center, the power density and efficiency of LLC converter is being pushed higher and higher. With the adoption of wide bandgap gallium nitride high electron mobility transistor (GaN HEMT), power device switching loss and conduction loss have been largely decreased and the switching frequency can be increased significantly. Thus the efficiency and power density promotion of LLC converter mainly dependent on the optimal design of deadtime and resonant parameters. In this paper, the ZVS working frequency boundary and the analytical calculation equations of both resonant and rectifier currents with the consideration of deadtime are deduced first, based on which a GaN device based LLC converter optimal design method is proposed with the realization of high efficiency and ZVS under wide input voltage range. An accurate GaN HEMT device model based LLC virtual prototype has been further constructed to verify the correctness of the proposed optimal design method. At last, the correctness of the proposed design method has been verified by experiment results.

Performance optimization on the irreversible regenerative Ericsson refrigeration cycle using electrocaloric materials as the working medium

A regenerative Ericsson refrigeration cycle using electrocaloric (EC) materials as the working medium is established. In accordance with the thermodynamic properties of EC materials, the mathematical expressions of the coefficient of performance (COP) and cooling rate of the regenerative EC Ericsson refrigeration cycle are derived. The cooling rate is selected as an objective function and optimized with respect to one of the two isothermal process temperatures in the Ericsson refrigeration cycle, Subsequently, the optimal ranges and bounds of the COP and dimensionless cooling rate are determined. Furthermore, the impacts of the heat leakage, finite heat capacities of heat reservoirs at high and low temperature sides, the Curie temperature of EC materials, the electric field intensity difference in the EC Ericsson refrigeration as well as the regenerator efficiency, internal irreversibility resulting from the thermal hysteresis of EC materials, etc. on the optimal performance of the regenerative EC Ericsson refrigeration cycle are revealed. The conclusions obtained are beneficial to the optimal parameter design of EC refrigerators.

An effective method to optimise plasma immersion ion implantation: Sensitivity analysis and design based on low‐density polyethylene

AbstractThe performance of polymer surface treatment using plasma immersion ion implantation (PIII) depends on many operating parameters, such as treatment duration, radiofrequency power, pulsed bias voltage and pulse repetition rate, and the ion fluence applied on the polymer surface. Currently, the identification of optimal operating parameters to achieve specific performance targets is heavily based on trail and error with extensive experimental testing. Herein, we present an optimisation method based on sensitivity analysis using polynomial chaos expansion and experimental design with Kriging surrogate model to greatly reduce the amount of experiments. The combined effects of PIII operating parameters on low‐density polyethylene surface modifications are investigated, demonstrating the validation and effectiveness of the method and design. The new approach offers highly accurate and computationally efficient way for achieving optimum radical density, wettability and optical transmittance that are important for biomedical applications.

Research on Vibration Reduction of Half-Vehicle Active Suspension Sys-tem Based on Time-delayed Feedback Control with Wheel Displacement

This paper proposes parameter controlling optimization of the time-delay feedback that is based on "equivalent harmonic excitation" in effective frequency band towards optimization of delay feedback control parameters for vehicle semi active suspension system. In this way, the optimal values of delay feedback control parameters based on different types of delay feedback control (displacement, velocity and acceleration) of wheels in the effective frequency band are obtained. Finally, through the stability analysis of vehicle semi-active suspension system based on different types of wheel delay feedback control and the numerical simulation analysis of time-domain response of suspension system performance evaluation index, the superiority of the time-delay feedback control strategy based on wheel displacement and the effectiveness and feasibility of the equivalent harmonic excitation optimization strategy are verified. Therefore, it provides a theoretical reference for the selection of time-delay feedback control strategy and the optimal design of time-delay feedback control parameters of vehicle active and semi-active suspension system.

FEM-Validated Optimal Design of Laminate Process Parameters Based on Improved Genetic Algorithm

In tape placement process, the laying angle and laying sequence of laminates have proven their significant effects on the mechanical properties of carbon fibre reinforced composite material, specifically, laminates. In order to optimise these process parameters, an optimisation algorithm is developed based on the principles of genetic algorithms for improving the precision of traditional genetic algorithms and resolving the premature phenomenon in the optimisation process. Taking multi-layer symmetrically laid carbon fibre laminates as the research object, this algorithm adopts binary coding to conduct the optimisation of process parameters and mechanical analysis with the laying angle as the design variable and the strength ratio R as the response variable. A case study was conducted and its results were validated by the finite element analyses. The results show that the stresses before and after optimisation are 116.0 MPa and 100.9 MPa, respectively, with a decrease of strength ratio by 13.02%. The results comparison indicates that, in the iterative process, the search range is reduced by determining the code and location of important genes, thereby reducing the computational workload by 21.03% in terms of time consumed. Through multiple calculations, it validates that “gene mutation” is an indispensable part of the genetic algorithm in the iterative process.

Modal characteristics of harmonic gear transmission flexspline based on orthogonal design method

Abstract The flexspline features several modal characteristics that are related to its structural parameters, which could impose an impact on the stability and reliability of the system of harmonic gear transmission. In this article, we have integrated the method of orthogonal design with the approach of finite element, so as to study the modal characteristics of flexspline under varying structural parameters. Furthermore, we have analyzed the ways of how varying structural parameters could impose an impact on the first eight-order natural frequencies of flexspline. In addition, by adopting the method of range and variance analysis for the obtained data, we have examined the influence imposed by varying structural parameters on the modal characteristics of flexspline, which could lay a foundation for the optimal design of the structural parameters of flexspline.

Optimized Parameter Design of the Dual-Loop Control for Grid-Forming VSCs WithLCFilters

This article provides a simple methodology to achieve an optimized parameter design of the dual-loop control for grid-forming voltage source converters (VSCs) with <i>LC</i> filters. The optimized parameter design is conducted for the current inner loop and voltage outer loop independently without any coupling, and the design processes of these two loops are exactly the same. Moreover, in the proposed design, standard analysis and design tools, e.g., pole map and Bode-plot can be directly employed while complex formula solving is needless. Therefore, this methodology is easy to implement for a practical engineering. In addition, contrary to common sense, it has been identified that the proportional controller in the outer loop has a negligible impact on the control bandwidth of typical medium power rating VSCs and thus can be eliminated to further simplify the design process and control structure. The left resonant controller can then be refined to achieve a significantly improved dynamic performance of the output voltage of VSCs. Detailed processes and considerations of the proposed design methodology are introduced and analyzed. Its effectiveness and performance are carefully verified by experimental results from a single-phase scaled-down VSC prototype.

The identification of optimal operating parameters under high energy efficiency conditions for a single polymer electrolyte membrane (PEM) fuel cell

The performance of PEM fuel cells is influenced by several factors such as: the operating temperature of the cell, the reactant gas flow, work pressures, the reaction gas humidity. In the present work we aimed to identify the optimal values of these parameters for operation of a PEM cell to achieve maximum power in conditions of high efficiency; the technological possibilities of its use in a portable energy application have been evaluated. Experimental measurements regarding the integrating polymeric membrane in three different fuel cell construction designed were performed. The influence of the mechanical compression of the GDL diffusion layer on the total internal resistance of the cell was achieved by comparative analysis of the polarization curves. It was found that as the deformation level of the MEA increases, the power generated by the battery increases progressively. The resulting experimental data subsequently allowed the design and implementation of a PEM fuel cell assembly, fully functional at power level, corresponding to the number of constituent elements.

A Smart Decision Making System for the Selection of Production Parameters using Digital Twin and Ontologies

Currently, the industrial and economic environment is highly competitive, forcing companies to keep up with technological progress and to be efficient in terms of quality and responsiveness, not only to survive, but also to dominate the market. So, to achieve this goal, companies are always looking to master their production processes, as well as to enlarge their range of products, either by developing new products or by improving old ones. This confronts companies to many problems, including the identification of adequate and optimal production parameters for the development of their products. In this context, a decision making system based on digital twins (DT), case-based reasoning (CBR) and Ontologies is proposed. The originality of this work lies in the fact that it combines three emerging artificial intelligence tools for modeling, reasoning and decision making. Thus, this work proposes a new flexible and automated system that ensures an optimal selection of production parameters for a given complex product. An industrial case of study is developed to illustrate the effectiveness of the proposed approach.

Toward interpretable digital biomarkers of walking and reaching in Parkinson's disease.

Multimodal digital data registered with wearable biosensors have emerged as highly complementary of clinical pencil-and-paper criteria, offering new insights in ways to detect and diagnose various aspects of Parkinson's disease (PD). A pressing question is how to combine both the clinical knowledge of PD and the new technology to create interpretable digital biomarkers easily obtainable with off-the-shelf technology. Several challenges concerning disparity in biophysical units, anatomical differences across participants, sensor positioning, and sampling resolution are addressed in this work, along with identification of optimal parameters to automatically differentiate patients with PD from controls. We combine data from a multitude of biosensors registering signals from the central (electroencephalography) and peripheral (magnetometry, kinematics) nervous systems, inclusive of the autonomic nervous system (electrocardiogram), as the participants perform natural tasks requiring different levels of intentional planning and automatic control. We find that magnetometer data during walking, across a variety of amplitude and timing signals, provide optimal separation of PD from neurotypical controls. We conclude that using multimodal signals within the context of actions that bear different levels of intent, can be revealing of features of PD that would scape the naked eye. Further, we add that clinical criteria combined with such optimal digital parameter spaces offer a far more complete picture of PD than using either one of these pieces of data alone.

Effects of Misalignment on the Accuracy of Blackbody Cavity Sensor for Temperature Measuring

Blackbody cavity temperature sensor has been used in the field of radiation temperature measurement since its applicability in measuring the temperature of a liquid. A detector is always placed coaxially with the cavity to receive the radiant energy from the bottom of the cavity where the temperature is the same as the liquid to be measured. However, the accuracy problem still exists. Due to the deviation of the sensor&#x2019;s relative position, there is a deviation angle between the axis of the detector and of the cavity, which will cause the detector receives the radiation from the low radiant energy regions of the measuring cavity, and lead to a low precision of the measurement result. In this article, research is made to analyze the effects of the misalignment between the cavity and the detector as well as the influence of the length of isothermal zone and spot size when the detector is out of the axis. To verify the situations above, we set experiments that reference the actual conditions, results show good agreement with theoretical analysis. The results are helpful for the optimum parameter design of the blackbody cavity as well as determine the relative position of the detector and the cavity.

Application of WOA–SVR in Seed Vigor of High-Voltage Electric Field Treatment on Aged Cotton (Gossypium spp.) Seeds

When seeds are treated with a high-voltage electric field (HVEF) to improve seed vigor, due to the large differences in the biological electromagnetic effects on different types of seeds, the methods of variance analysis and regression analysis based on data statistics are generally used to construct the optimal electric field dose prediction model; however, the generalization performance of the prediction model tends to be poor. To solve this problem, the electric intensity, frequency and treatment time were taken as the input variables for hybrid support vector regression (SVR) analysis to establish the prediction model of the seed comprehensive germination index. The whale optimization algorithm (WOA) was used to optimize the kernel parameters of the SVR. The optimized hybrid WOA–SVR model predicted the optimal comprehensive germination index of aged cotton (Gossypium spp.) seeds to be 329, the optimal HVEF dosage was 3.64 kV/cm × 99 s, and the frequency was 1.4 Hz. The aged cotton seeds were treated with the optimal HVEF and the germination test was carried out. Compared with the check (CK), the comprehensive germination index of seeds increased by 48%. The research results provided a new method and new idea for the optimal design of parameters for seed treatment with HVEF.

Multi-objective optimal design of permanent magnet eddy current retarder based on NSGA-II algorithm

As a new type of vehicle auxiliary braking device, permanent magnet eddy current retarder has a wide application prospect. In this paper, the linear layer analysis method and non-dominated sorting genetic algorithm-II (NSGA-II) are combined to optimize the parameters of permanent magnet eddy current retarder. Firstly, based on the linear layer model, the mathematical optimization model of permanent magnet eddy current retarder is established by taking the radial length of permanent magnet, the thickness of permanent magnet, the number of permanent magnets and the thickness of conductor disk as design variables, the braking torque and eddy current loss as optimization objectives. Secondly, the NSGA-II algorithm is used to optimize the braking torque and eddy current loss of the permanent magnet eddy current retarder. Finally, the performance of the permanent magnet eddy current retarder after the optimization of the structural parameters is carried out by using ANSYS software to verify the accuracy and feasibility of the optimization results. The optimization algorithm used in this article solves the problem of poor adaptability to environmental changes and premature convergence in the late evolution of standard genetic algorithm. The results show that the NSGA-II algorithm based on the layer analysis model has better computational results in the optimal design of structural parameters than the standard genetic algorithm.

Investigation on the regenerative Brayton refrigeration cycle performances using novel Mn-Fe-P-Si composite material with thermal hysteresis as the working medium

MnFeP(As, Ge, Si) series compounds are three kinds of MnFe-based magnetocaloric materials, which have giant magnetocaloric effect. In this work, the experimental characteristic curves of new style Mn-Fe-P-Si materials, numbered as 1: Mn1.32Fe0.67P0.52Si0.49, 2: Mn1.37Fe0.63P0.5Si0.5, and 3: Mn1.35Fe0.66P0.5Si0.5 are presented. Based on the experimental data of these component materials and thermodynamic analysis method, a novel composite material is put forward. The optimal molar mass ratios of the composite material are obtained and they are 0.22, 0.33, 0.45, respectively. A regenerative Brayton refrigeration cycle employing the optimal composite material with thermal hysteresis as the working medium is built. By numerical calculation, the influences of thermal hysteresis on the main thermodynamic quantities are evaluated. The results show that the thermal hysteresis of the working medium results in a decrease of 13.6%, 14.6%, 18.8%, and 16.1% of the cooling quantity, net cooling quantity, optimally working temperature range, and coefficient of performance, respectively. These conclusions are beneficial to the optimal parameter design and performance improvement of active magnetic refrigerators.

Research on vibration reduction of semi-active suspension system of quarter vehicle based on time-delayed feedback control with body acceleration

In this paper, the mechanical model of two-degree-of-freedom vehicle semi-active suspension system based on time-delayed feedback control with vertical acceleration of the vehicle body was studied. With frequency-domain analysis method, the optimization of time-delayed feedback control parameters of vehicle suspension system in effective frequency band was studied, and a set of optimization method of time-delayed feedback control parameters based on “equivalent harmonic excitation” was proposed. The time-domain simulation results of vehicle suspension system show that compared with the passive control, the time-delayed feedback control based on the vertical acceleration of the vehicle body under the optimal time-delayed feedback control effectively broadens the vibration absorption bandwidth of the vehicle suspension system. The ride comfort and stability of the vehicle under random road excitation are significantly improved, which provides a theoretical basis for the selection of time-delayed feedback control strategy and the optimal design of time-delayed feedback control parameters of vehicle suspension system.

Artificial intelligence in aircraft design and the role of professor V.G. Maslov’s scientific school in the process of its development

The article was prepared for the 95th anniversary of the birth of Valentin Grigorievich Maslov, Doctor of Science (Engineering), Professor, founder of the school for optimal design of aircraft engine parameters, head of the engine CAD system department (Department 6) of the applied research laboratory (ONIL-2) of Kuibyshev Aviation Institute named after academician S.P. Korolyov. The stages of creating the theoretical foundation for optimal design of aircraft are discussed. The role of Professor V.G. Maslov in the formalization of knowledge in aircraft design in a context of uncertainty and the importance of multi-criteria assessment of design solutions are described. The work of Department 6 ONIL-2 (KuAI-SSAU), led by Valentin Grigorievich, provided Samara scientific school with a leading position in the field of optimal design of engines for aircraft of varying function. These works contributed to the formation of a modern understanding of the intellectualization of systems and the successful start of work in the field of their creation. The development of Professor V.G. Maslovs ideas in the works of his students is shown.

Channel/rib patterns optimization of a proton exchange membrane fuel cell by combining down-the-channel performance model and genetic algorithm

It is necessary to establish an effective method to guide the flow channel design of the bipolar plate (BPP) to obtain the optimal performance of the proton exchange membrane fuel cells (PEMFC). Most of the existing works focused on the optimization of constant channel dimensions and structures without considering achieving the flow channel's optimal local performance. In this study, an approach combining the down-the-channel performance model and genetic algorithm (GA) is developed to optimize BPP channel/rib patterns for fuel cells. A flow channel is divided into several segments, and the channel dimensions of each segment are brought into the down-the-channel performance model as variables to obtain the optimal parameter design by GA. The model and the optimization results are validated by the CFD and local current density experiment. The performance results of both CFD and local current density experiments are in good agreement with the results of the down-the-channel performance model. It is found that the cell performance of variable rib to channel width ratio (RCWR) design along the flow channel is better than the performance of constant RCWR design. Performance improvements are more significant when the sum of rib and channel width (SRCW) is higher, and the output voltage is lower. Smaller SRCW design can effectively reduce the ohmic losses and concentration polarization which is beneficial to cell performance, and as the SRCW is reduced, the performance improvement of variable RCWR design along the flow channel is less necessary. A guide for the design of the cathode flow channel RCWR from upstream to downstream is provided.

An Anti-Jamming Method against Two-Dimensional Deception Jamming by Spatial Location Feature Recognition

Interrupted sampling repeater jamming (ISRJ) is an effective method for implementing deception jamming on chirp radars. By means of frequency-shifting jamming processing of the target echo signal and pulse compression during image processing, a group of false targets will appear in different spatial locations around the true target. Extracting the features of these false targets is complex and limited to existing countering methods against ISRJ. This paper proposes an anti-jamming method to identify the spatial location characteristics of two-dimensional deception false targets. By adjusting the parameters of the radar transmitted signal, the method simultaneously transmits the anti-jamming signal and carries out false target identification and elimination in the range and azimuth dimensions. Eventually, the optimal signal parameter design of the anti-jamming signal is obtained by comparing different anti-jamming strategies in the range dimension. The validity of the proposed method is proved by deducing the mathematical model between the spatial distribution characteristics of the false targets and the radar transmitted signal parameters and demonstrated by simulations.

Improving the electromagnetic compatibility of electronic products by using response surface methodology and artificial neural network

PurposeThe purpose of this study is to use the Taguchi Method for parametric design in the early stages of product development. electromagnetic compatibility (EMC) issues can be considered in the early stages of product design to reduce counter-measure components, product cost and labor consumption increases due to a number of design changes in the R&D cycle and to accelerate the R&D process.Design/methodology/approachThe three EMC characteristics, including radiated emission, conducted emission and fast transient impulse immunity of power, are considered response values; control factors are determined with respect to the relevant parameters for printed circuit board and mechanical design of the product and peripheral devices used in conjunction with the product are considered as noise factors. The optimal parameter set is determined by using the principal component gray relational analysis in conjunction with both response surface methodology and artificial neural network.FindingsMarket specifications and cost of components are considered to propose an optimal parameter design set with the number of grounded screw holes being 14, the size of the shell heat dissipation holes being 3 mm and the arrangement angle of shell heat dissipation holes being 45 degrees, to dispose of 390 O filters on the noise source.Originality/valueThe optimal parameter set can improve EMC effectively to accommodate the design specifications required by customers and pass test regulations.

Study on Oil-water Two-phase Migration Mechanism of Low Permeability Fractured Core based on the Online NMR Testing

Understanding the dynamic migration mechanism of oil-water two-phase is the key to improve the effect of water injection development in low permeability fractured reservoir. Based on artificial fracturing of core and basic physical parameter testing, the online NMR displacement experiments of cores with different fracture widths are conducted to analyze the oil-water dynamic distribution characteristics and migration mechanisms. The experimental results show that when water breaks through at the outlet, oil volume in the small pores is basically unchanged. In the large pores it decreases to a certain extent, while in the fracture it decreases greatly. When the displacement is over, oil volume in the small pores still changes little, while it decreases greatly in the large pores, and it is almost zero in the fracture. With the decrease of fracture width, the recovery ratio when waterflooding front breaks through and the final recovery ratio after displacement increase gradually. The contribution proportion of recovery ratio in the fracture decreases as a whole, while in the large pores it increases gradually, and in the small pores it decreases slightly. The research results lay a foundation for the optimal design of fracture parameters and the adjustment of water injection development technology policy in low permeability fractured reservoir.