最新刊期
卷 57 ， 期 8 ， 2023
- 摘要：Due to circumferential pressure gradients and complicated secondary flows, pressure-side regions of turbine endwalls are one of the most difficult-to-cool regions. This study aims to solve this cooling problem by placing two rows of discrete film holes in the upstream region of the endwall passage inlet near the pressure side to obtain curtain cooling with unique cooling characteristics. A pressure sensitive paint(PSP)technique was implemented to examine film cooling patterns of curtain cooling over the endwall surfaces and its effects on discrete film injection within the passage in detail. Furthermore, an optimized endwall film cooling scheme was obtained by applying curtain cooling to the endwall. The experimental results reveal that curtain cooling has quite different cooling patterns compared with discrete film cooling within the passage. The curtain cooling was slightly influenced by the pressure gradients circumferentially across the endwall passage, resulting in efficient cooling for the pressure-side region and even for the endwall passage throat and its downstream regions. Increasing coolant rates enhances film cooling effectiveness for curtain cooling and improves film cooling performance of the discrete film holes within the endwall passage. The optimized cooling scheme improves film cooling effectiveness over the endwall by 33% relative to a baseline cooling configuration. Additionally, flow structures at the vane cascade exit demonstrate that the optimized cooling configuration reduces the cascade aerodynamic losses, somewhat.关键词：aero-engine;turbine endwall;film cooling;curtain cooling;aerodynamic loss376|10|0更新时间：2025-05-08
- 摘要：In view of the uneven distribution of axial inlet flow and the backflow of the blade passage caused by the large volute width and short blades of the multi-blade centrifugal fan, this paper proposes a design method of variable chord length blades. With the multi-blade centrifugal fan impeller as the research object, the parametric optimization of the impeller leading edge is carried out. The leading edge is constructed using the Bezier curve with five control points, the support vector regression proxy model is established, the optimization objectives for efficiency and static pressure are set, and the parameters of the selected control points are optimized by genetic optimization algorithm. The variable chord long blade design improves the flow capacity of the multi-blade centrifugal fan, resulting in a maximum volume flow increase to 35.7 m3/h. The analysis of the flow field reveals that the impeller designed with variable chord length blades has a more uniform flow distribution along the blade height direction, especially in the area near the shroud side where the velocity is less than 0, and the flow ratio of the disk section increases by 29.8%. The channel backflow phenomenon is significantly improved, and the working ability of the impeller with variable chord length blades is relatively stronger. Based on the variable chord length blade design, the aerodynamic performance of the multi-blade centrifugal fan is greatly improved, the operating range in the large flow direction is widened, the efficiency increases by 4.9% under the small flow condition, and the static pressure capacity of the fan increases by up to 91.1 Pa. This research provides the theoretical basis and engineering practice value for the internal flow control and the variable chord length blade design of multi-blade centrifugal fans.关键词：variable chord length blade;multi-blade centrifugal fan;support vector regression;numerical analysis240|7|0更新时间：2025-05-08
- 摘要：A numerical study was carried out for the effects of different film hole arrangements on film cooling characteristics of turbine endwall with mid-passage gap leakage. Firstly, the film cooling effectiveness of a gas turbine endwall was measured with PSP method, and the results was adopted for turbulence model validation. Then mesh independence analysis was carried out for the model under study. On this basis, the film cooling and aerodynamic loss characteristics under different film hole arrangements of the endwall with mid-passage gap leakage were studied. The film cooling and aerodynamic characteristics under five different blowing ratios(M=0.5, 1.0, 1.5, 2.0, 2.5)and four film hole arrangements were analyzed in detail. Results show that when the blowing ratio is 0.5, the endwall film cooling effectiveness reaches its maximum value under arrangement A(S=0.065Cax, γ2=-56.6°; S is the distance between second group film holes and mid-passage gap, Cax is the axial chord length of the blade, and γ2 is the compound angles of the second group film holes). With the increase of blowing ratio, the film coolant jets off from the endwall surface, and the film cooling effectiveness near the film hole decreases. Under the four different film hole arrangements, the total pressure loss coefficient in the near wall area decreases with the increase of the blowing ratio. The decrease amplitude under arrangement A is the greatest. The film hole arrangement has little effect on the endwall film cooling under a low blowing ratio(M=0.5). The film cooling effectiveness(S=0.1Cax, γ2=30°)is the highest under arrangement D and a high blowing ratio(M=2.5).关键词：turbine endwall;film cooling;film hole arrangement83|12|0更新时间：2025-05-08
- 摘要：Due to the strong aerodynamic interaction between the two airfoils, the aerodynamic characteristics of tandem configuration is obviously different from single airfoil at low Reynolds number. To further explore the aerodynamic features of tandem configurations with respect to the relative geometric positions, on account of the preliminarily conducted wind tunnel experiments, unsteady computational simulations on a group of tandem configurations from NACA0030 have been carried out using the in-house codes based on hybrid grid and Reynolds averaged Navier-Stokes equations, and the effects of spacing and stagger on general aerodynamic characteristics and vortex structure in flow field were compared and presented quantitatively in low Reynolds number regime(Re=1.2×105). The final results demonstrate that when the relative chordwise distance is less than 1.2 and the relative normal distance is less than 0.8, the aerodynamic interference effect of the two airfoils is more significant. And the closer the distance between the two airfoils is, the more severe the aerodynamic interaction effect is. Comparing with the stagger, the spacing effect is more significant. By designing a reasonable spacing and stagger, the aerodynamic efficiency of tandem configuration could be greatly increased by 50% comparing to single configuration. Therefore, tandem configuration can be used as an aerodynamic design solution for future micro aerial vehicle in low Reynolds number regimes.关键词：tandem configuration;aerodynamic interaction;low Reynolds number flow;flow separation;lift enhancement171|5|0更新时间：2025-05-08
- 摘要：The solid-air accumulated in liquid hydrogen has certain safety hazards. In order to investigate the growth evolution and oxygen solute distribution of solid-air dendrite driven by heat-solute coupling, a non-isothermal quantitative phase field dendrite growth model is established in this paper, which is applied to study the morphological evolution, growth rate and oxygen solute distribution of solid-air dendrites under different subcooling degrees and boundary heat flux conditions. The results show that: compared with isothermal simulation, the non-isothermal simulation considering latent heat of solidification can reproduce the growth process of solid-air dendrites more realistically, and the peak oxygen mass fraction is reduced by 8.5%—14.6% compared with isothermal simulation; the growth rate of dendrites and the maximum oxygen mass fraction show a positive correlation with the initial subcooling degree, and the maximum oxygen mass fraction in the solid-liquid interphase zone can reach 0.401 when the initial subcooling degree is 4 K; the presence of boundary heat flux can significantly change the temperature distribution in the computational domain and thus affects the growth pattern of solid-air dendrites; heat input slows down the growth of dendrites, while heat extraction makes the dendrite arms grow more prosperous and robust, and the solid fraction under heat extraction and heat input conditions are 138% and 69% of those without boundary heat flux, and the maximum oxygen mass fractions are 146% and 94% of those without boundary heat flux, respectively. This study improves the understanding of the solid-air dendrite growth behavior in liquid hydrogen and may provide theoretical guidance for the safe use of liquid hydrogen systems.关键词：solid-air dendrite;non-isothermal phase field;morphological evolution;liquid hydrogen100|22|0更新时间：2025-05-08
- 摘要：To reveal the charge formation mechanism and accumulation behaviors in a liquid hydrogen flow condition, the binary system of solid air particles in liquid hydrogen pipe flow was taken as the object, and the open source software platform OpenFOAM was adopted. Several additional functions, including force model on the solid particles, electrification model by LH2-wall friction, low-conductivity fluid charge model and particle charge model, were established and incorporated into the software platform to extend its predictive abilities. With the multi-phase particle-in-cell(MP-PIC)method, the coupled calculation of liquid-solid two-phase flow field and electric field was reached. Based on this extended-function software, the charge accumulation in the LH2 flow event with solid air particles was simulated, and the influences of particle size and air amount on charge accumulation performance were analyzed. The results show that the charge density in a pure LH2 flow event is about 1.358×10-7 C/m3 when the flow rate is 3 m/s, while the charge density in a solid air particle existence case is higher than this value by three orders of magnitude. Therefore, the charge risk in the solid air particle existence case is greater than that in a pure liquid hydrogen flow condition. Most solid air particles, with a diameter of 0.1 mm, have the charge amount of about 3.16×10-12 C to 1.58×10-11 C. Increasing the particle size or decreasing the air content in the system increases the proportion of charged particles, as well as the average particle electric quantity. The present study is of theoretically instructive significance to the design and safety protection of liquid hydrogen pipeline systems.关键词：liquid hydrogen pipe flow;solid air particle;charge accumulation;numerical simulation71|8|0更新时间：2025-05-08
- 摘要：When the cryogenic thermal shield is removed, the fuel ice uniformity of cryogenic target deteriorates significantly due to the introduction of a large amount of radiant heat from the ambient environment. For this problem, a three-dimensional model was established for a six-entrance cylinder-hohlraum cryogenic target with removable and fixed thermal shields based on the Boussinesq hypothesis and the discrete coordinate(DO)radiation model in the present study. The FLUENT software is used for numerical simulation to investigate transient temperature characteristics of the capsule surface during the thermal shield removal process, and analyze the influence of the structure and position of the fixed thermal shield on these transient temperature characteristics. The results show that during the removal of the cryogenic thermal shield, the temperature of the capsule surface increases rapidly under the combined effect of the external radiation, the convection in the hohlraum and the conduction through the fill tube, while the maximum temperature difference on the capsule surface first increases rapidly to the peak, then decreases, and finally tends to be stable. The fixed thermal shield structure can effectively prevent the external high-temperature radiation, reducing the temperature rise in the maximum temperature on the capsule surface by 39.5% and improving the uniformity of capsule surface temperature by 39%. Reducing the size of windows in the upper and lower side walls or increasing the distances from the walls to the capsule center can further reduce the temperature rise of the maximum temperature on the capsule surface and suppress the deterioration of temperature uniformity. The sensitivity of capsule surface temperature to the change in positions of the front upper and lower side walls of the fixed thermal shield is higher than that of other side walls. The results are instructive for the capsule surface temperature control during cryogenic thermal shield removal.关键词：cryogenic target;transient characteristics;thermal shield;numerical simulation74|24|0更新时间：2025-05-08
- 摘要：In order to study the staged oxy-fuel combustion behavior of high-alkali coal, the NOx generation and ash deposition of high-alkali coal in the staged oxy-fuel combustion were investigated simultaneously in this study. With the help of two-stage furnace system, the NOx generation and ash deposition of high-alkali coal in the staged oxy-fuel and air combustion were compared firstly, and then the effects of total oxygen content and oxygen content in the primary combustion zone under the staged oxy-fuel condition were subsequently studied. The experimental results show that compared with the air-staged combustion, the smaller conversion ratio of fuel-nitrogen to NO(6.8%、9.6%)and the less deposited ash(62.4、147.3 mg)can be achieved in the staged oxy-fuel combustion when the oxygen contents were 21%. In the staged oxy-fuel combustion, the mass of ash deposit increases in an approximately linear way as the total oxygen content increases by 15%—50%. For each 10% increase in total oxygen content, the mass of ash deposit increases by about 40 mg. The conversion ratio of fuel-nitrogen to NO also shows an upward trend, but it changes slightly when oxygen content varies from 15% to 30%. With the oxygen content in the primary combustion zone increase by 25%—60%, both the conversion ratio of fuel-nitrogen to NO and mass of ash deposit increase. For each 10% increase in oxygen content in the primary combustion zone, the mass of ash deposit increases by about 21 mg. This study indicates that the NOx generation and ash deposition of high-alkali coal in the staged oxy-fuel combustion should be investigated simultaneously, which could provide comprehensive information for promoting the clean and safe utilization of high-alkali coal, as well as reducing the CO2 emission.关键词：oxy-fuel combustion;staged combustion;high-alkali coal;NOx;ash deposition77|23|0更新时间：2025-05-08
- 摘要：To complement the experimental data of the surface tension of new environmentally-friendly olefin refrigerant, and to provide the reliable data for the calculation of phase change heat transfer and two-phase flow, the surface tension of cis-1, 1, 1, 4, 4, 4-hexafluoro-2-butene(R1336mzz(Z))and the mixtures with POE lubricant(type: SL-32S)was measured using the differential capillary rise method. The mass fractions of the studied lubricant for the mixtures are 0.130%, 0.536%, and 1.040%, respectively. The measuring temperature was from 243 K to 363 K, and the measurement standard uncertainty for the surface tension was less than 0.16 mN·m-1. Results show that the surface tension of the mixtures increases with the lubricant concentration. Moreover, the surface tension of the mixtures shows a reduced increase amplitude as the temperature rises, compared with that of pure R1336mzz(Z). The experimental surface tension was correlated as the empirical expression, and the average absolute deviations between the experimental data and the calculated values for the pure R1336mzz(Z)and R1336mzz(Z)/SL-32S mixtures were 0.07 mN·m-1and 0.14 mN·m-1, respectively. The obtained results can provide the essential surface tension data for the further application of R1336mzz(Z)to various types of refrigeration/heat pump systems.关键词：refrigerant R1336mzz(Z);surface tension;polyolester lubricant63|5|0更新时间：2025-05-08
- 摘要：The performance indexes of 3D CAD software are difficult to quantify due to the lack of benchmarks while the existing evaluation methods for software performance are not intuitive enough. To overcome these shortcomings, a visual evaluation method for the performance of 3D CAD software is proposed based on the automatic testing and triangular transformation. Firstly, the unified interfaces and the automatic testing tool for 3D CAD software are developed and the test cases are designed. Then the unified automatic test of different types of 3D CAD software is conducted by utilizing the same testing tool and test cases to obtain the performance data. And the performance indexes are quantified based on the testing results of foreign benchmark software. Secondly, the preprocessed performance data are utilized to construct the normalized data matrixes according to the importance of different performance indexes. And the harmonic curves of coarse and fine granularities corresponding to the performance of 3D CAD software are constructed based on the triangular transformation. The validity of the performance data is checked by both the Grubbs' Criterion and intuitive analyses, where the latter is based on the idea of optimistic lock. Finally, the performance evaluation results of 3D CAD software are obtained qualitatively through the intuitive cluster analyses of the harmonic curves in variable granularities. The results of the case study demonstrate that the proposed method can analyze the performance differences between domestic software and benchmark software and intuitively obtain the performance evaluation results of 3D CAD software, which provides users intuitive decision basis to choose an appropriate software. Besides, compared with the general evaluation method based on analytic hierarchy process, the reliability and effectiveness of the proposed method are proved.关键词：3D CAD software;automatic testing;triangular transformation;variable granularity;visual evaluation75|52|0更新时间：2025-05-08
- 摘要：An improved adaptive layering algorithm with STL model feature details retained is proposed for problems of the traditional adaptive layering algorithm for 3D printing, such as complicated calculation, inability to eliminate the influence of the step effect on the model, failure to retain model features, and easy loss of model features. The improved algorithm first determines whether the current layer contains significant feature edges. It then adaptively determines the layer thickness by the angle between the two adjacent triangular mesh vectors for the case with such edges, by the angle between the triangular mesh vector and the forming direction for the case without such edges, and by the change in the number of closed curves in the adjacent tangent planes for the case where the model has feature offsets. Finally, the minimum value of the adaptive layer thickness in the above three cases is used as the basis for the current layering. The results show that, for the adopted dinosaur model, the proposed algorithm not only retains the detailed features of the model, but also significantly improves the modeling quality; the proposed algorithm has an accuracy 28.6% and 31.7%, respectively, higher than that of the vector adaptive layering algorithm based on the triangular slice method and the adaptive layering algorithm that only retains the model features. The algorithm reduces the influence of step effect and model feature loss and offset on the printing quality, improving the model printing accuracy to a certain extent.关键词：3D printing;STL model;adaptive layering;model feature;triangular mesh47|23|0更新时间：2025-05-08
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Novel Design and Grasping Experiment of a Hand-Assisted Exoskeleton Driven by Tendon-Sheath Actuator
摘要：A hand-assisted exoskeleton system driven by a tendon-sheath actuator is designed to address the problem that, in the aerospace and industrial fields, fatigue damage to hands is caused and grasp strength is reduced, when personnel wear gloves to perform tasks, as finger joints are subject to the glove woven fabric compression. For this system, a PID force control method with speed as the inner loop and force as the outer loop is used, and the output force is fed back with a force sensor. The location of the hand-assisted exoskeleton cable slot is optimized by mechanics modeling. The grasping experiment for the designed exoskeleton system reveals that the assisted exoskeleton can reproduce all 33 grasp types in the Feix taxonomy; the grasping force of the exoskeleton at the fingertip can reach 14 N; with the exoskeleton, human finger joints can move by more than 63% of the independent finger bending range; the Pearson correlation coefficient of the angle of the metacarpophalangeal joint, proximal interphalangeal joint, and interphalangeal joint can reach more than 0.90; the peak RMS values of the brachioradialis muscle and the radial extensor carpi longus muscle decreased by 37.86% and 62.46%, respectively. The experimental results indicate that the designed hand-assisted exoskeleton can significantly reduce hand muscle energy consumption.关键词：tendon-sheath;hand assist;exoskeleton mechanism;gripping experiment;static analysis120|26|0更新时间：2025-05-08 - 摘要：The common spatial pattern(CSP)algorithm is modified and introduced into the field of diagnosing rolling bearing faults in order to address the issues that the traditional method faces a challenge in effectively extracting the features of rolling bearing fault features and the single-direction vibration signal is susceptible to missing fault information. An intelligent diagnosis method for rolling bearings with a modified common spatial pattern(MCSP)algorithm and multi-source feature fusion is proposed. Firstly, CSP is used to combine three-direction vibration signals of bearings at the data and feature levels, realizing full extraction of fault information while shortening data processing time. Then, the strategy of subclass spatial filter ensemble is improved at the decision level to construct the optimal spatial filter, so as to effectively extract the space domain features under different bearing health states. Finally, a support vector machine(SVM)is utilized to identify faults of various types and degrees. A bearing dataset of the laboratory and a publicly available one from SLIET and are used for test verification. The results show that, compared with the CSP approach, the proposed method improves the average recognition accuracy of bearing faults by 3.04% and 6.26% for both datasets, respectively. It achieves an average recognition accuracy of over 99% and an average time of less than 0.1s. This verifies the proposed method has better fault identification accuracy and running efficiency.关键词：common spatial pattern;multi-source feature fusion;fault diagnosis;feature extraction;support vector machine64|23|0更新时间：2025-05-08
- 摘要：To explore the influence of joint clearance on the dynamic characteristics of flexible manipulators, a coupled dynamic model considering joint clearance and arm flexibility is established and the dynamic characteristics are analyzed. Firstly, a contact force collision model and an improved friction calculation model are used to characterize the joint clearance. Secondly, a dynamic analysis model, with the planar rotational joint clearance considered, for flexible manipulators is constructed by using the assumed mode method, and the corresponding coupled dynamic equation is derived based on the Lagrange method. Finally, the influence of clearance value and elastic modulus parameters on the dynamic characteristics of flexible manipulator systems is analyzed. The simulation results show that, as the joint clearance value increases, the contact collision force increases, while the collision frequency decreases, which makes the translational acceleration at the end of the manipulator increase and the motion fluctuation frequency decrease. When the clearance value is 0.1 mm, the contact impact force is increased to 17.76 times that without clearance. The flexible arm can alleviate the internal collision of the joint and decrease the amplitude of the collision force by more than 80%, but the reduction in the elastic modulus can escalate the acceleration amplitude at the end of the manipulator. The analysis results can provide reference for the research of reliability and stability of robot systems.关键词：flexible manifulator;joint clearance;coupling dynamics;coutact collision78|5|0更新时间：2025-05-08
- 摘要：This paper addresses issues in the current design of electric quadrotor fixed-wing hybrid unmanned air vehicles(EH-UAVs), including a lack of theoretical basis for the layout configuration selection, a lack of analysis and evaluation methods for the wind disturbance rejection capability in the quadrotor mode, the issue that design methods for the electric propulsion systems of most EH-UAVs are to design the quadrotor system and fixed-wing system independently, and the issue that design methods for the conceptual design are mainly the traditional sequence design methods without fully considering the complex coupling relationships caused by the mutual transfer of parameters between various disciplines such as geometric shape, aerodynamics, trimming and stability, propulsion system, weight, wind disturbance rejection capability in the quadrotor mode, and endurance performance. Based on the proposed improved surrogate model based concurrent subspace optimization(CSSO)architecture, this paper establishes a multidisciplinary optimization(MDO)method for the conceptual design of EH-UAVs. This is accomplished by building geometric shape parameterization models and aerodynamic grid division models, aerodynamic and flight performance analysis models for different flight modes, evaluation and analysis models for wind disturbance rejection capability in the quadrotor mode, and the proposed electric propulsion system models. The proposed MDO method and the discipline analysis models are applied to the conceptual design process of a small EH-UAV. A prototype of the EH-UAV is fabricated based on the MDO results. The flight test results of the prototype show that the flight performance meets the design requirements, and with a 2.8% reduction in takeoff weight, the endurance time is improved by approximately 14.1%, and the maximum wind speed that the EH-UAV can resist is increased by approximately 3.5%. This verifies the feasibility and correctness of the MDO method proposed in this article, which can provide guidance for the research and application of EH-UAVs.关键词：electric quadrotor fixed-wing hybrid unmanned air vehicle;conceptual design;wind disturbance rejection capability;electric propulsion system;multidisciplinary design optimization81|9|0更新时间：2025-05-08
- 摘要：To shorten the length and time of global path planning for agricultural robots and to obtain better safe paths, a multi-strategy improved chimp optimization algorithm(MIChOA)is proposed. Firstly, a good point set strategy is introduced in the population initialisation stage to improve the population diversity, thus improving the traditional chimp optimization algorithm; then, a normal stochastic cosine convergence factor strategy is proposed based on the actual chimp search process to balance the global exploration and local exploitation capability of the algorithm; secondly, a stagnation perturbation strategy with a greedy competition mechanism is used when the algorithm falls into a local optimum stagnation to speed up the algorithm's jumping out of the local optimum and finding the global optimum. Finally, a standard test function is used to verify the performance of the MIChOA algorithm in finding the global optimum, and an environmental raster map with 111 obstacles is created for corresponding experimental simulations. The MIChOA algorithm is applied to agricultural robot path planning and compared with the four relatively excellent improved ChOA algorithms. The results show that the MIChOA algorithm features high search accuracy, stable convergence and good robustness in terms of both single-peak and complex multi-peak functions; the MIChOA algorithm outperforms the other four improved ChOA algorithms in path search performance, with a 28.01% reduction in path length, 54.58% reduction in search time and 85.87% reduction in the number of iterations.关键词：agricultural robot;chimp optimization algorithm;path planning;local optimum91|5|0更新时间：2025-05-08
- 摘要：For problems of low deployment accuracy, complex control, and motion instability of deployable mechanisms exposed in engineering due to the characteristics of light weight, large flexibility, and large size of components, the absolute nodal coordinate formulation(ANCF)is used to analyze the impact of component flexibility on the dynamic characteristics of deployable mechanisms with scissor-like elements from the perspective of multiple flexible bodies. Firstly, based on ANCF, a new non-locking planar beam element is proposed. Secondly, considering the configuration characteristics and motion conditions of deployable mechanisms with scissor-like elements serving in spatial mechanisms such as solar panels and extension arms, a dynamic model for deployable mechanisms with three scissor-like elements is established using the first type Lagrange equation. Finally, the influence of rod flexibility on dynamic behaviors of deployable mechanisms is analyzed by this model. The research results show that the proposed new element improves the computational efficiency by 18.2% via solving the element locking problem, and the flexibility of components can lead to resonance of different components, affecting the deployment accuracy of deployable mechanisms. The research can provide theoretical reference for the deployment of large/ultra large extension arms in orbit.关键词：absolute nodal coordinate formulation;scissor-like element;deployable mechanism;non-locking element;flexible multi-body dynamics45|11|0更新时间：2025-05-08
- 摘要：In order to address the problems of uneven initial positions, ease of reaching local optimum, and low search accuracy in traditional particle swarm algorithm(PSO), a novel PSO algorithm based on an improved Sine chaotic mapping is proposed. The improved Sine chaotic mapping technique is used instead of the traditional pseudo-random number method for generating the initial particle population to enrich the population diversity. Two new position update mechanisms are added to the original basic position update formula. A Gaussian mutation operator is introduced to achieve a dynamic balance between the exploration and exploitation performance of the algorithm, as well as to help particles effectively jump out of the local optima during the iteration process. For three classical engineering optimization design problems with constraints, simulation experiments are performed for the proposed algorithm based on a benchmark test function consisting of seven single-peaked functions, six multi-peaked functions and ten fixed-dimensional functions. This algorithm is then compared with several other popular PSO variants. Simulation results show that the novel PSO algorithm based on improved Sine chaotic mapping has faster convergence speed and higher optimization-seeking accuracy than those of other PSO variants. For the benchmark test functions, it ranked first in 20 of them, accounting for about 87% of the total testing functions. The proposed algorithm ranked first in the overall performance of pressure vessel and I-beam design optimization, and can be used to solve some practical engineering optimization problems.关键词：PSO algorithm;chaotic mapping;Gaussian mutation;benchmark functions;engineering problems71|14|0更新时间：2025-05-08
- 摘要：For the severe corona, found through ultraviolet observation, at insulator strings of the 750 kV substation end portal frame, which is more severe than that in other positions, a difference analysis on the voltage equalization characteristics of different types of insulator strings is proposed. Firstly, a three-dimensional model of 750 kV substation is built, and the voltage equalization characteristics of insulator strings with and without jumpers are compared. The overall model is simplified by the submodel mesh and detail simplification technology. Calculation results show that the error of the simplified model is only 0.5%, and the calculation time decreases by 78.9%. Then, two-parameter and four-parameter structural analysis methods are used to synchronously analyze the relative distances, pipe diameters and ring diameters of shielding rings and grading ring. Finally, the optimal parameter configuration of the insulator string grading ring and shielding rings with and without jumpers is obtained. According to the results, to achieve the same shielding effect as insulator strings with jumpers, insulator strings without jumpers require an increase in center distance, ring diameter and pipe diameter of the shielding ring by 100 mm, 210 mm and 10 mm respectively, and an increase in the lifting distance and ring diameter of the grading ring by 270 mm and 40 mm, respectively. The study results indicate that the insulator strings of the substation end portal frame need to be equipped with larger grading rings and shielding rings. The structural optimization process also verifies the effectiveness of the multiparameter structural analysis method.关键词：substation;portal frame;insulator string;electric field;structural optimization;multiparameter54|23|0更新时间：2025-05-08
- 摘要：A multi-scale regional attention InfoGAN license plate recognition network is proposed for difficult recognition of license plate images that are skewed, obscured, distorted, or blurred. First, a multi-scale regional attention license plate super-resolution module is proposed based on the InfoGAN framework. Mutual information constraints on color distribution and character structure features are introduced to improve the network's discriminant performance in different feature dimensions. Key character features in distorted and blurred low-resolution license plate images are reconstructed. Second, in the absence of the location label information of license plate characters, the license plate characters and background in the global feature map are decoupled by a multi-scale region attention mechanism to progressively weight different regions of the feature map at different scales, improving the network's performance to focus on the saliency of character regions and resist the interference of background noise regions. Finally, a multi-scale semantic license plate character extraction module is proposed to decode and recognize the character features in the reconstructed license plate image. Both the self-built XAUAT-Parking dataset and the publicly available CCPD dataset are used for license plate recognition accuracy experiments. The experimental results show that the proposed network has an average recognition rate of 99.3% for the CCPD dataset and of 99.2% for the self-built dataset. The research results show that the network features accurate license plate recognition and great robustness in complex scenes.关键词：license plate recognition;attention mechanism;super-resolution;generative adversarial network85|10|0更新时间：2025-05-08
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