最新刊期
卷 51 ， 期 11 ， 2017
- 摘要：At large pre-swirl, the flow loss induced by the inlet guide vane(IGV)usually degrades the economy of the regulation scheme. Aiming at reducing flow loss at large pre-swirl, the sweep angle at the leading edge of the IGV is changed in forward direction relative to the shroud line. The traditional shape of the shroud of the inlet pipe connecting with the IGV is modified to the cone. The secondary flow initiated within the improved design overcomes the considerable hub flow separation caused by the centrifugal force at the high pre-swirl. The situation of the entropy increase is heightened at the impeller inlet. The new structure efficiently improves the polytropic efficiency and the total pressure ratio of the centrifugal compressor within a wide operation range for the pre-swirl of +60 and -60 degrees. The improvements are enhanced with the increasing flow rate. While the left margin in the operation range remains constant, the right margin obviously widens.关键词：centrifugal compressor;inlet guide vane;sweep-angle;flow control636|6|2更新时间：2025-07-09
- 摘要：To protect the gas turbine blades suffering from the hot gas by adapting the film cooling technology, a novel film cooling geometry with an upstream ramp is proposed in view of the requirement for further increasing adiabatic film cooling effectiveness and decreasing expense of coolant. The performance of film cooling with upstream ramps is numerically investigated with k-ε turbulence model. The effects of arrangement for four different ramps, including the undivided ramp, the ramp divided in the lateral sides, the ramp divided in several positions and the ramp divided in the center, on flow structures are analyzed. The adiabatic film cooling effectiveness and heat transfer coefficient of these four film cooling geometries are compared. The results show that the intensity of entrainment is sensitive to the length of ramp and is independent on the ramp arrangements. Different vortex structures are induced due to the different arrangement for ramps. The ramp divided in the center region generates a pair of vortexes which rotates in the opposite direction with the kidney vortexes, and this pair of vortexes contributes to the lateral spreading of coolant, which increases the film cooling performance. The ramp divided on both sides generates a pair of vortexes which rotates in the same direction with the kidney vortexes, and this pair of vortexes lifts off the coolant further, which increases the film cooling performance. The highest adiabatic film cooling effectiveness in the spanwise direction and the highest NHFR(net heat flux reduction)are observed in the case of the ramp divided in the center.关键词：film cooling;divided upstream ramp;arrangement;cooling performance558|5|0更新时间：2025-07-09
- 摘要：To research the nozzle cavitation and near-field spraying characteristics, visualization experiments were carried out using a high-speed camera and a single transparent up-sized nozzle to observe the nozzle cavitation and near-field spraying behavior of three ethanol-diesel blended fuels with the volume fractions of ethanol of 0%, 5%, 10%. The normalized cavitation length, discharge coefficient, cavitation number, Reynolds number and near-field spraying cone angle were analyzed under the injection pressures of 0.16-0.36 MPa. The three ethanol-diesel blended fuels were namedE0D100N0,E5D90N5 andE10D85N5 respectively, wherein the letters of E, D and N represent ethanol, diesel and n-butanol respectively while the subscripts indicate the volume fraction of each component. The experimental results showed that, with the increase of volume fraction of ethanol, the threshold injection pressures corresponding to original cavitation and super cavitation were decreased, and the periods of developing cavitation were shortened but the periods of supercavitation were extended. During the no-cavitation stage, the change of volume fraction of ethanol had no obvious influence on near-field spraying cone angle; during the developing cavitation stage, the near-field spraying cone angle increased with the increase of volume fraction of ethanol; and during the hydraulic flip stage, the near-field spraying cone angles of three blended fuels were all close to zero. Under the same injection pressure, the discharge coefficients and the Reynolds numbers ofE0D100N0,E5D90N5 andE10D85N5 increased in sequence, and when hydraulic flip appeared inside the nozzle, the discharge coefficients and the Reynolds numbers of these three blended fuels were all decreased sharply.关键词：ethanol-diesel;nozzle;cavitation;visualization experiment532|6|3更新时间：2025-07-09
- 摘要：Focusing the problem that running aero-engine absorbs rain droplets, a numerical algorithm is proposed to reveal the coupling flow behavior between gas flow and wall film. The air flow and wall film coupling behavior on convex/concave surfaces are numerically investigated. It is concluded that the wall film migrates from the concave surface to the convex surface because the quadratic flow militates in curved channel. There is a wall film accumulation area on both side of the convex surface along the flow direction, and the thickness of the wall film on both side of the concave surface decreases. The flow Mach number has negative effect on the thickness of the wall film on the convex and concave surfaces. The wall film mass flux has positive effect on the thickness of the wall film on the convex and concave surfaces. The increasing inlet flow angle increases the wall film thickness on the convex surface and decreases the thickness on the concave surface. The wall film on the convex surface contracts along the flowing direction more obviously with the increasing wall-curvature. The wall film fluctuates due to the pressure fluctuation on the phase interface. The flow Mach number and inlet flow angle have positive effect on the intensity of fluctuation of wall film.关键词：convex/concave surface;wall film behavior;coupling flow;numerical study502|5|0更新时间：2025-07-09
- 摘要：Considering the low methane conversion rate of traditional tubular reforming reactor, a multi-inlet micro-tubular reforming reactor for hydrogen production was designed in this paper, and the influences of operation parameters on the reforming performance were studied by COMSOL multiphysics software. The results indicated that the raise of reaction temperature from 773 K to 973 K would improve the methane conversion rate as well as H2 and CO mole fractions. With the increase of steam/carbon ratio from 2 to 4, the methane conversion rate is improved, while H2 and CO mole fractions are decreased. And also, the methane conversion rate and H2 and CO mole fractions present a sawtooth shape fluctuation, however showing an overall rising trend along the axis of the reactor and reach their maximum values at the outlet. In addition, compared the multi-inlet tubular reforming reactor with the traditional tubular reactor, a conclusion can be drawn that the methane conversion rate of present reactor is higher than the traditional tubular reactor when the reaction temperature varies from 600 K to 1 100 K, and the methane conversion rate reaches 93% in the range of 873-973 K. When the steam/carbon ratio changes from 2 to 5, the methane conversion rate of this reactor is higher than that of traditional tubular reactor. However the increase of steam/carbon ratio exhibits no significant effect on the improvement of methane conversion when the steam/carbon ratio is higher than 4. Thus, the optimal steam/carbon ratio is from 3 to 4.关键词：multi-inlet feeding;hydrogen production;reforming reaction;reactor447|5|1更新时间：2025-07-09
- 摘要：A typical compressor stage was taken as the research object and the effect of wall roughness variation on the aerodynamic performance of axial compressor was investigated quantitatively with a three dimensional numerical simulation. The underlying mechanism of compressor performance degradation caused by wall roughness was revealed. The results show that the increasing wall roughness reduces total pressure ratio and the isentropic efficiency of compressors, and the greater the roughness, the faster the performance degradation. When the wall roughness exceeds 90 μm, the total pressure ratio and isentropic efficiency of compressors decrease by 2.58% and 7.15% respectively. The viscous dissipation of airflow in near wall region, enhancement of the mixing and blockage of airflow in the separation zone and loss of the shock wave are the main reasons of worsened compressor performance. In addition, with the increasing wall roughness, compressor characteristic curves move toward mass flow decreasing direction, and characteristic parameters near stall point decrease faster. The steady working range of compressors is thus widened, but flow capacity is greatly lowered. When wall roughness exceeds 150 μm, stall condition occurs in advance, and compressor steady working range is rapidly reduced by 6.21%.464|6|6更新时间：2025-07-09
- 摘要：Following energy transport principle and fractal geometry theory, the fractal network fitted for the fluid flow transport in the blade internal passages was generated, and the fractal tree-like branching microchannel was designed as an internal cooling structure for turbine blade. In the experiment system of convection cooling for gas turbine internal microchannel, the effects of inlet Reynolds number and heating power on the Nusselt number, friction factor and enhancement heat transfer factor of air flow were investigated. The results reveal that as Reynolds number ranges from 194 to 19 400, the average Nusselt number of air increases by 148.5%, the friction factor decreases from 0.78 to 0.009 and the maximum value of enhancement heat transfer is obtained at inlet Reynolds number=17 300. When the heating power ranges from 10 W to 110 W, the average Nusselt number reduces by about 35.9%, the friction factor changes slightly and the best enhancement heat transfer factor is observed at P=10 W. The local Nusselt numbers of the first and second level microchannel are greatly promoted by the branching structure in combination with the conjugation heat transfer effects. In comparison of the first three levels microchannels, the heat transfer performance of the last level microchannel is more obviously affected by Reynolds number and heating power.关键词：gas turbine;blade internal cooling;fractal tree-like microchannel;heat transfer enhancement;experimental study608|5|0更新时间：2025-07-09
- 摘要：In order to overcome the low catalytic activity and stability of ZSM-5 zeolite due to its microporous and long diffusion path to the substrates and products, a nanosheet MFI(NS-MFI)zeolite with higher activity and stability was synthesized by hydrothermal method, and it was characterized by XRD, BET, SEM, TEM and NH3-TPD methods. The supercritical catalytic activity of NS-MFI zeolite was studied by cracking n-dodecane and kerosene, and the activity was compared with that of conventional ZSM-5 zeolite. Compared with ZSM-5, NS-MFI showed higher BET surface area, larger volume and ultrathin lamellar structure. During the cracking of n-dodecane, the NS-MFI zeolite showed higher gas generation rate, selectivity of alkenes and heat sinks because of its special morphological structure; during the cracking of kerosene at 550 ℃, NS-MFI showed equivalent activity to ZSM-5 zeolite, because large amount of cycloalkanes exist in kerosene which is difficult to be cracked. While at 600 ℃, the NS-MFI zeolite showed better performance. However, the activities of kerosene cracking by the two zeolites were both lower than that of n-dodecane cracking. So, it can be concluded that porous and ultrathin lamellar structure is beneficial to the diffusion of reactants and products, and hence improving the catalytic activity and stability.关键词：nanosheet MFI zeolite;catalytic cracking;hydrocarbon fuel;light alkene;heat sink439|6|4更新时间：2025-07-09
- 摘要：To further study the rheological characteristics of high-solid sewage sludge, revised Herschel-Bulkley model was selected according to total solid(rTS)of sludge to simulate flow behavior within digesters reasonably. The effects of sludge type, total solid, the range of shear rate, temperature on the critical shear stress in the flow curve were investigated in the experiments. Anaerobic digested sludge with total solid of 5.2%-15.8% was sheared by employing shear rate sweep ranging from 0.01 s-1 to 1 000 s-1 for steady rheological tests. The results indicate that for the sludge with rTS <8.8%, the flow curve is well fitted by Herschel-Bulkley model. While for the sludge with rTS>8.8%, a critical shear stress appears in the flow curve within the range of 1-10 s-1, and the flow curve is fitted by the revised Herschel-Bulkley model. The critical shear stress is correlated to the total solid and the range of applied shear rate, but not to sludge type, composition, tested temperature or digestion time. The critical shear rate (?overγ)c corresponding to the critical shear stress shows a linear relationship with rTS of digested sludge.关键词：high-solid sludge;rheological behaviors;critical shear stress;revised Herschel-Bulkley model461|6|2更新时间：2025-07-09
- 摘要：Based on the study on the performance of gas in an ultra-precision air bearing stage, the effects of velocity slip and viscosity at micro scale on the performance of air-bearing stage are studied. The modified film flow model was established by the theory of gas lubrication and the research of slip and viscosity in micro scale. The numerical solution of the Reynolds equation is obtained by the finite difference method. The influences of slip and viscosity on performance of air-bearing stage at different gas supply pressures and gas film clearances are analyzed by solving Reynolds equations. The result shows that the loading capacity is smaller and the stiffness is larger when considering the slip and viscosity, while the influencing trend of gas supply pressure and gas film clearance on the air bearing stage is kept the same, only the degrees of change are affected. When the slip and viscosity are taken into account at the same time, the loading capacity is decreased by 21.95%, and the maximum stiffness is increased by 15%. The optimum performance parameters of the air bearing stage are less than the ideal optimum performance parameters when slip and viscosity are considered. The optimum gas film clearance is changed from the original 10 μm to 6 μm. Finally, the test results showed that when the slip and viscosity are considered at the same time, the stiffness of the air bearing stage is close to the actual working condition. The simulation curve of the loading capacity is in good agreement with the test curve, and the average error between the test and simulation values is about 9.59%.关键词：air bearing stage;velocity slip;viscosity;loading capacity;stiffness457|6|1更新时间：2025-07-09
- 摘要：A finite element analysis model with conical asperity is proposed to investigate the normal contact characters of rough surfaces in the micro perspective. The total normal elastic contact force acting on the single-cone contact region is obtained through definite integrate of the inverse hyperbolic cosine stress. A formula fitting the normal deformation of cone tip and the contact radius is given. Digital simulations show that although the inverse hyperbolic cosine stress has a natural logarithmic singular spot at the tip of the cone(at the center of the contact region), the total normal elastic contact force acting on the single-cone contact domain is bounded. The normal elastic contact load on single cone increases at first and then decreases with the increase of the half apex angle. The joint interface's total normal contact load increases with the decrease of the surface roughness. When the normal maximal deformation increases very evidently, the increase of the total normal contact load on joint interface is very small. The larger the half apex angle is, the larger the single-cone normal contact stiffness becomes. When the normal deformation of the cone tip increases, the single-cone normal contact stiffness slightly decreases at first and then keeps constant. When the normal critical deformation is smaller, the joint interface's total normal contact stiffness has an approximate linear increase with the increase of the normal critical deformation. The smaller the surface roughness is, the more evidently the joint interface's total normal contact stiffness increases. When the normal critical deformation is larger, the joint interface's whole normal contact stiffness approaches constant.关键词：conical asperity;rough surface;normal contact load;normal contact stiffness;inverse hyperbolic cosine417|6|2更新时间：2025-07-09
- 摘要：Aiming at the impact of foundation vibration on pressure-flow characteristics of electromagnetic directional valve, the mathematical model and simulation model of the electromagnetic directional valve under the foundation vibration are established by controlling differential pressure of valve port to simulate the pressure loss. The transient flow force and electromagnet force under the foundation vibration are considered, and the accuracy of the model is verified experimentally. The influences of foundation vibration parameters and structure parameters of the valve on the pressure-flow characteristics and the flow fluctuation are discussed. The results show that electromagnetic directional valve with small flow and low pressure loss is more suitable for the foundation vibration environment. The pressure-flow characteristic reduction zone and the flow fluctuation failure area under foundation vibration are obtained, and the pressure-flow characteristic reduction area for the differential pressure of 0.7 MPa gets 45 times of that of 0.4 MPa. The flow fluctuation amplitude can be decreased by reducing the spool mass and increasing the damping coefficient and the spring stiffness ought to be less than 5 kN/m.关键词：foundation vibration;electromagnetic directional valve;pressure-flow characteristic;flow fluctuation438|6|3更新时间：2025-07-09
- 摘要：A design idea of flexible hinge under the constraints of bar and plate is proposed to solve the problem that the design method of flexible hinge with single rotation degree of freedom is imperfect and its rotation angle is small, based on the theory of freedom and constraint topologies(FACT). Flexible hinges with large rotational angles are designed according to the proposed design idea. Single rotation degree of freedom flexible hinges under bar constraints are classified based on the concepts of constraint space, intersection point and intersection pitch. The idea of adding bar constraint according to the position of the constraint is applied to the design of flexible hinges under bar constraint. Flexible hinges with single rotation degree of freedom under the plate constraint are classified based on the relationship between plate and bar constraints, and the idea of adding plate constraint is given by considering different effects of the position and the deformation of the plate on flexible hinges. This idea is applied to the design of a bend intersection flexible hinge and a torsion non-intersection flexible hinge. A kind of flexible hinges with single rotation degree of freedom and a large action angle is put forward through a series combination of these two kinds of hinges mentioned above. Finite element simulation and analysis are performed on the rotational angle and the rotational accuracy. It is shown that when the coefficient of safety is 12, the rotational degree of the flexible hinge achieves ±20° and the radial translational stiffness is 43.20 N/m, i.e., the flexible hinge has a large rotational angle and high translational stiffness. A comparison with the existing flexible hinge shows that the rotational angle of the resulting hinge is larger than that of the existing flexible hinge.关键词：flexible hinge;single rotation degree of freedom;freedom and constraint topologies(FACT);finite element analysis569|6|1更新时间：2025-07-09
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Surface Morphology Models of Cycloid and Pin Teeth Based on Fractal Theory and Differential Geometry
摘要：The key point to analyze the contact characteristics of cycloid and pin wheels is to establish a contact model with comprehensive embodiment of the gross feature and micro-characteristic. A surface topography model of rough surfaces is established based on Weierstrass-Mandelbrot function and differential geometry. The function of cycloid is determined by using a vector function with modification being taken into account. The unit normal vector is calculated with the application of differential geometry. The 2D sections of a pin tooth and a cycloid tooth which is assumed as isotropic are plotted by MATLAB. The contact model between cylinder and rigid flat is established, a parameter called equivalent contact angle is proposed, and the relations of the angle with fractal dimension, characteristic scale and radius of cylinders are studied. Furthermore, the contact proportionality coefficient that is used to describe the contact area between cycloid and pin tooth surfaces is given. The coefficient is less than 1 in any case, and the value for the area between pin tooth and inter part of cycloid is much larger than that for the area in outer part of cycloid. It is indicated by analysis that the value of the coefficient decreases with the increase of the fractal dimension, increases at first and then decreases with the increase of the center distance, and increases with the increase of pin tooth radius, characteristic scale, and number of pin teeth.关键词：cycloid and pin teeth;fractal theory;differential geometry;Weierstrass-Mandelbrot function;vector function;surface morphology model405|6|2更新时间：2025-07-09 - 摘要：The features and methods of calculating damping coefficients and dissipation energy in different contact force models are analyzed to study the influences of the existing contact force models for dynamic analysis of multibody systems involving joints with clearance. The dissipation energies of different models are compared based on a single ball collision system. On the basis of this analysis, a slider crank mechanism is used to study influences of different contact force models on efficiency, stability and result of computation for multibody system dynamics. Results show that the increase of dissipation energy in a contact force model accelerates the stability of dynamic results of multibody system, and an appropriately selected contact force model can improve the computation efficiency and stability of the dynamic system. More dominant contact force models for different restitution coefficients are obtained by considering stability, efficiency of computation, and applicability.关键词：multibody system;joint with clearance;energy dissipation;contact force693|6|5更新时间：2025-07-09
- 摘要：A robust beam forming(AN-RBF)scheme with artificial noises is proposed to improve the physical layer for the wireless communication. Firstly, the channel estimation is used to get the imperfect channel state information(CSI)of a legitimate receiver and the statistical CSI of eavesdroppers. Then, the AN-RBF scheme adds artificial noises into transmission signals to maximize the secrecy rate under constraints of the transmit power and the secrecy rate outage probability. The AN-RBF scheme only needs to get the imperfect CSI of the link to the legitimate receiver and the statistical CSI of the link to eavesdroppers, therefore, reduces the system overhead. Adding artificial noise effectively reduces the signal-to-interference-and-noise ratio(SINR)received at eavesdroppers. Thus, the AN-RBF scheme improves the physical layer security performance of multiple-input single-output(MISO)wiretap channels. Simulation results and a comparison with the isotropic AN scheme in the same simulation environment show that the AN-RBF scheme improves the secrecy rate approximately by 2 bit?(s?Hz)-1.关键词：wireless communication;physical layer security;robust beamforming;artificial noise458|7|0更新时间：2025-07-09
- 摘要：To improve the secondary electron emission coefficient and attenuation characteristic becomes the key to the application technology. Taking MgO film and MgO/Au composite films as the research objects of secondary electron emission materials, the change law of secondary electron effect over time is revealed by continuous electron beam bombardment on the film. The exponential decay of the sample time was tested and the influence of conductivity and dielectric constant on attenuation rate was explored. The mechanism of secondary electron emission was discussed under model hypothesis. The concept of potential electron and tablet capacitance model were put forward, and the theory model of the secondary electron emission process was then established. The expression of experimental value of the induced current and the secondary electron emission coefficient was obtained and coincided with the test result trend of actual sample, namely, the attenuation rate of secondary electron emission material properties was positively correlated to the film conductivity. It is concluded that the proposed theoretical model effectively explains the attenuation mechanism of the dielectric film secondary electron emission, and facilitates improving the attenuation performance of secondary electron emission material.关键词：MgO film;secondary electron effect;dielectric film;attenuation mechanism334|6|3更新时间：2025-07-09
- 摘要：Studies of rotor kinetic energy participating in frequency regulation are mainly focused on the control strategies, and less attention is paid on the ability of rotor releasing kinetic energy under different working conditions. A simplified dynamic simulation model of a 1.5 MW doubly-fed induction wind turbine generator(DFIG)was established with Matlab/Simulink, and verified by the operating data of a 1.5 MW wind turbine generator. The duration time was proposed and the variation of the ability of rotor releasing kinetic energy was obtained in a low and middle speed region(6-8 m/s). Then a rotor inertial response controller was designed. The dynamic responses under different wind speed conditions were investigated as the system frequency falls, and the response curves of revolving speed and active power were completed. The results show the general applicability of this model. The time of rotor releasing energy reaches up to 15 s, and the active power increases by 15%. The ability of rotor releasing kinetic energy decreases with the increasing wind speed from 6 m/s to 8 m/s.关键词：wind turbine generator;frequency regulation;control strategy;rotor kinetic;rotor inertial response567|6|1更新时间：2025-07-09
- 摘要：To meet the requirements of global optimal and real-time obstacle avoidance in mobile robot path planning, a novel method based on the fusion of improved A* algorithm and dynamic window approach is proposed. Combining Manhattan distance with Euclidean distance, a more appropriate heuristic function is designed for A* algorithm. Then a key node culling scheme is introduced into the traditional A* algorithm to remove the redundant nodes. An evaluation function considering globally optimal path is constructed. The dynamic window approach based on the evaluation function is applied to perform real-time dynamic path planning to guarantee the smoothness of path and the local obstacle avoidance ability as holding the global optimality of path. The experimental results demonstrate that compared with traditional A* algorithm, the smoother path is found, the ability of dynamic obstacle avoidance is more obvious and the control parameters for robots are obtained. The proposed method outperforms traditional dynamic window approach in guaranteeing the global optimality of path planning, and the path distance reduces from 28.879 m to 22.285 m.关键词：mobile robot;path planning;A* algorithm;dynamic window approach;dynamic obstacle avoidance889|7|43更新时间：2025-07-09
- 摘要：To overcome the shortcomings of the traditional thermocompressors, a new-type thermocompressor system is proposed, where a linear motor is designed as power source, and the cylinder wall and piston serve as a regenerator. The effects of heating temperature, linear motor driving power, working fluid and inflation pressure on the operating characteristics of the new thermocompressor system were investigated experimentally. The results indicate that the working fluid with larger heat capacity ratio facilitates improving the performance of the compressor system. The peak-peak pressure in the system can be heightened by increasing inflation pressure, but the effect is not obvious. Taking He4 as working fluid, when the inflation pressure is 0.96 MPa and the heating temperature is 330 ℃, the pressure ratio of the new hot compressor system is 1.14, which can meet the specific requirement for the pulse tube refrigerator. The experimental research on the output power of the new thermocompressor system is carried out by the gas reservoir with a small orifice. It is found that the thermocompressor system is endowed with a maximum external capacity corresponding to the optimum opening of the orifice. With the same working fluid and inflation pressure, when the heating temperature is 603 ℃ and the gas reservoir volume is 0.518 L, the output power of the thermocompressor reaches the maximum value of 15.6 W.关键词：thermocompressor;experimental research;thermodynamics;linear motor;regenerator528|6|1更新时间：2025-07-09
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A Multi-Source Statistics Data-Driven Method for Remaining Useful Life Prediction of Aircraft Engine
摘要：A multi-source statistical data-driven method for remaining useful life(RUL)prediction of aircraft engines is proposed to solve the difficulty that the multivariate degradation model cannot be constructed. To quantify the degradation process of aircraft engines with the multi-source monitoring data, an information fusion model based on Euclidean distance is established. To estimate the RUL of aircraft engines, the arithmetic model of aircraft engines consisting of Wiener process with nonlinear drift is considered to derive the probability density function of RUL. The performance of the proposed method is verified by C-MAPSS. The simulations show that the proposed method improves coefficient of determination and total score compared with the existing results. The proposed approach provides new insights to RUL prediction of the other nonlinear degradation systems.关键词：remaining useful life;aircraft engine;probability density function;statistical data-driven475|6|22更新时间：2025-07-09 - 摘要：To coordinate the contradiction between ride comfort and handling stability of damping continuously variable semi-active suspension, and considering the satisfied nonlinear constraints for damping force, a hybrid model predictive control algorithm for semi-active suspension is proposed. A single wheel model of semi-active suspension is established, and the optimal objective function that comprehensively determines comfort and stability and the satisfied nonlinear constraints for semi-active suspension are put forward. The semi-active suspension hybrid system is described with mixed logic dynamic modeling method. A finite-horizon optimal control problem of semi-active suspension is set up following model predictive control theory. For the convenience of solving, the nonlinear constrained optimization problem can be transformed into a mixed integer quadratic programming one including real and binary vectors, and solved by means of branch and bound algorithm. The simulations on random profile and single sine wave bump pavement show that the proposed hybrid model predictive control algorithm improves the comprehensive performance of damping continuously variable semi-active suspension system effectively compared with passive suspension and the traditional linear quadratic regulator algorithm, and better control performance is realized under different road input excitations and at different vehicle speeds.关键词：semi-active suspension;non-linear constraints;mixed logical dynamical;hybrid model predictive control;mixed integer quadratic programming500|6|5更新时间：2025-07-09
- 摘要：Cavitation state recognition is one of the difficulties in condition monitoring of centrifugal pump. A method for cavitation state recognition of centrifugal pump based on deep learning is developed. The vibration signals on pump casing under three conditions are collected, and the band matrixes of modified octave as well as matrixes of time-frequency features of vibration signals are established. The deep learning network is constructed based on auto-encoder, the features of input data are learned automatically by unsupervised training, and the parameters of the network are adjusted by supervised training. Four cavitation states of centrifugal pump are recognized by deep learning network. It demonstrates that based on band matrixes of modified octave or matrixes of time-frequency features, the deep learning network is effective for recognizing four cavitation states and outperforms BP neural network, especially for slight cavitation state.关键词：centrifugal pump;cavitation state recognition;deep learning;auto-encoder;neural network874|7|11更新时间：2025-07-09
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