最新刊期
卷 54 ， 期 1 ， 2020
- 摘要：To understand the penetration mechanism of ambient gases in glass shell materials of ultra-high vacuum electronic devices in depth, numerical simulation of gas permeation including dissolution and diffusion processes in glass was studied with the methods of giant canonical Monte Carlo and molecular dynamics. The solubility coefficients of oxygen, helium, hydrogen and water vapor molecules in two kinds of glass structure, together with the diffusion coefficients, permeability coefficients and motion trajectories of oxygen and hydrogen molecules in soda-lime glass, were calculated based on the COMPASS(Condensed-phase optimi-ed molecular potentials for atomistic simulation studies)force field. The calculation results show that a kind of gas having a higher affinity with glass has a higher solubility coefficient. Metal ions distributed in glass make the si-e of pores in glass smaller, which results in a lower gas solubility coefficient of soda-lime glass. Both of rising environment tempera关键词：glass structure;gas permeation;dissolution and diffusion;numerical simulation460|4|1更新时间：2025-07-09
- 摘要：Many chaos control methods in power systems only focus on a simple two-dimensional power system model. To solve chattering and singularity in sliding mode control widely used in chaos control of power system, a synergetic control method for a four-dimensional power system is presented to suppress its chaotic oscillation. Employing bifurcation diagram and Lyapunov exponential spectrum, the parameter range of chaotic oscillation in the four-dimensional power system is sought out. The dynamic models of energy storage devices and static var compensators are introduced to construct a controlled six-dimensional power system. The corresponding macro variables are defined for the controlled power system, the synergetic control inputs with continuous control law are designed, and a control block diagram for the four-dimensional chaotic power system is obtained. Numerical simulation shows that the designed synergetic controller can restore the controlled power system from chaotic oscillation sta关键词：four-dimensional power system;chaotic oscillation;chaos control;synergetic control271|5|8更新时间：2025-07-09
- 摘要：To solve the problem of imaging difference and too few training samples in infrared-visible images matching, a matching network based on intra-class transfer learning is proposed. The network consists of feature extraction subnetwork and metric subnetwork. Owing to four convolutional neural network(CNN)branches in feature extraction subnetwork, the proposed network is referred to as PairsNet for short. The CNN branches extract infrared and visible image features. The visible image is used as the source domain and the infrared image as the target domain. By reducing the maximum mean discrepancy distance of intra-class samples in the two domains, more accurate sample distribution alignment is achieved in the intra-class feature space. The metric subnetwork uses two full connection layers and one softmax layer in series to evaluate infrared-visible image matching performance. Infrared and visible image data sets are built for end-to-end training and testing. The experimental results show关键词：infrared-visible images;image matching;transfer learning254|4|1更新时间：2025-07-09
- 摘要：A nonlinear model predictive controller based on a support vector machine and a sequential quadratic programming algorithm is designed to solve problems of overpressure in the position control of asymmetric valve-controlled hydraulic cylinders and pressure shock caused by spool reversal. The support vector machine is used to fit the relationship between the control signal and the piston speed and to obtain an approximate model of the system, and the sequential quadratic programming algorithm is employed to obtain outputs of the controller. The valve spool is not reversed and the piston displacement quickly reaches the target position without overshoot by adding output constraints and constraints satisfying input. Numerical simulation results show that when the signal of relative position errors is greater than 8%, the control signal output by the controller is greater than 90% of the maximum control signal, which effectively shortens the response time of the system. At the same time, a关键词：asymmetrical valve-controlled hydraulic cylinder;model predictive control;support vector machine;sequential quadratic programming algorithm225|5|1更新时间：2025-07-09
- 摘要：Aiming at the problem that the noise such as baseline drift, power frequency and myoelectric interference in the ECG signal interferes with subsequent signal analysis and diagnosis, an ECG adaptive denoising method with ensemble empirical mode decomposition(EEMD)and improved threshold function is proposed. The noisy ECG signal is firstly decomposed into a set of intrinsic mode functions(IMFs)by EEMD. The IMFs are distributed from high frequency to low frequency. Then, -ero-crossing rate is used as a criterion to adaptively determine the noise category of each IMF. If the IMF contains high frequency noise, an improved threshold function in combination with the advantages and disadvantages of the soft and hard threshold functions is proposed to remove high frequency noise in the IMF component. If the IMF includes a low-frequency baseline drift, the median filter is chosen to suppress the baseline drift. Finally, all the processed IMFs are superimposed to reconstruct the de-noised ECG sig关键词：electrocardiogram denoising;set empirical mode decomposition;-ero crossing rate;improved threshold function1272|4|8更新时间：2025-07-09
- 摘要：The aerodynamic performance and flow fields of the tangential admission volute and the admission volute coupled with downstream vanes were experimentally measured and numerically simulated in this research. The total pressure loss, outlet flow angle and mass flow rate of the tangential admission volute at three different outlet Mach numbers and of tangential admission volute coupled with downstream vanes at four different inlet total pressures were measured. The flow fields of the experimental tangential admission volute models were numerically investigated using three-dimensional Reynolds-averaged Navier-Stokes(RANS)equations and SST turbulence model. The simulated numerical aerodynamic parameters of the tangential admission volute were in good agreement with the experimental data and the accuracy of the presented numerical method was validated. Results showed that the outflow angles of the tangential admission volute and that of the tangential admission volute coupled with downstream关键词：steam turbine;tangential admission volute;aerodynamic performance;flow field220|4|0更新时间：2025-07-09
- 摘要：To analy-e the thermal-fluid-structure characteristics of swirl cooling, a thermal-fluid-structure coupled model and a fluid model were established. The swirl cooling performance for two models was compared under the same boundary conditions. The temperature and structure characteristics of the thermal-fluid-structure coupled model were analy-ed. Results showed that the solid wall heat transfer has little influence on the cooling air flow field, but the target wall heat transfer intensity is affected by the solid wall heat transfer to some extent. The target wall heat transfer intensity distribution for the thermal-fluid-structure coupled model is more uniform, while the solid wall heat transfer intensity between the high and low heat transfer regions decreases along the cooling air flow direction gradually. The heat transfer intensity of the high heat transfer region corresponding to swirl no--le inlets increases along the cooling air flow direction. The target wall average heat trans关键词：thermal-fluid-structure coupling;swirl cooling;solid wall heat transfer320|4|5更新时间：2025-07-09
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Investigations of Flow and Heat Transfer Performance in a Blade with Trailing-Edge Cutback and Lands
摘要：RANS(Reynolds-averaged Navier-Stokes)equations combined with transition model SST --Re- are adopted to investigate the flow and heat transfer performance in a gas turbine blade with trailing edge cutback and lands. At three inflow turbulence intensities, three mainstream Reynolds numbers and three coolant ejection rates, heat transfer coefficient distributions and aerodynamic loss in blade with trailing-edge cutback and lands are compared with those in trailing-edge cutback blade without lands. With the existing experimental data, the reliability of numerical methods is validated at a range of operation conditions. The results show that, as the inflow turbulence intensity increases, heat transfer coefficients on blade surface for the blade with lands are gradually increased. However, the heat transfer coefficients on trailing edge cutback are not sensitive to the variations of inflow turbulence intensity. The energy loss coefficient and total pressure loss coefficient in b关键词：gas turbine;trailing edge cut-back;land;heat transfer;loss257|4|5更新时间：2025-07-09 - 摘要：To fulfil the requirements of wide-range duty cycle adjustment and low jitter for the clock signals of high-speed analog-to-digital converters(ADC), a charge-pump type clock management circuit was proposed, which uses charge pumps to form two closed loops, achieving wide-range duty cycle stabili-ation and adjustable two-phase non-overlapping clock generation. The charge pump-s integral function of the clock phase extends the range of the input clock duty cycle stabili-ation and significantly suppresses the effect of power supply noise on the falling edge of the clock. Designed in a 0.18 -m standard CMOS process, the post-layout simulation results showed that the input signal frequency range of the proposed clock management circuit is 40-200 MH-, and the clock duty cycle can be stably adjusted into the range of 45%-55% within an input duty cycle of 20%-80%. Under the condition of 200 mV power supply interference, the output clock jitter can be reduced by a factor of ten compared with关键词：pipeline ADC;clock management circuit;charge pump;duty cycle stabili-ation292|4|1更新时间：2025-07-09
- 摘要：The traditional lithium-ion battery health state estimation method only uses the battery ohmic internal resistance as a single-factor evaluation index which leads to a big error. Therefore, it is necessary to construct a multi-factor evaluation model with three parameters including battery ohmic internal resistance, polari-ation internal resistance and polari-ation capacitance. The first-order RC equivalent circuit model serves as the basic circuit model. The accuracy of the selected circuit model is verified by a simulation. The equivalent circuit model parameters, namely the ohmic internal resistance, polari-ation internal resistance, and polari-ation capacitance are obtained via the cyclic aging experiment for the offline identification. The offline identification results verify the certain relationship of the above three model parameters with health state. The weight coefficients of the corresponding model parameters are solved with constrained least squares algorithm, and the Kalm关键词：lithium-ion battery;state of health;Kalman filter;constrained least squares287|4|8更新时间：2025-07-09
- 摘要：Aiming at the problem that the underwater gliding snake-like robot has input constraints and unknown external disturbance during implementing gliding, the backstepping control method based on Nussbaum function and nonlinear disturbance observer is proposed to improve its pitching motion tracking performance. The vertical plane motion of the under-actuated underwater gliding snake-like robot is analy-ed and conditionally simplified, and the corresponding kinematics and dynamic equations are obtained. Nussbaum function and hyperbolic tangent function are combined to deal with the problem of system control input saturations, which avoids the controller singularity of the latter, and the nonlinear disturbance observer is used to effectively observe and compensate the external complex disturbance. The backstepping controller is designed for pitching motion tracking, where the computational expansion caused by the virtual item in the backstepping method is eliminated by the dynamic surface m关键词：underwater gliding snake-like robot;pitch motion;disturbance observer;input constraints;backstepping control247|4|4更新时间：2025-07-09
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