最新刊期
卷 46 ， 期 5 ， 2014
- 摘要：Abstract:The Carrousel oxidation ditch with complex shape was optimized to improve the flow mixture character in an oxidation ditch,and reduce energy consumption.The gas-liquid two-phase flow model with RNG k-ε turbulent model was numerically solved to investigate the turbulence characteristics of the oxidation ditch with or without guiding bafflers downstream the surface aerators,and the VOF(volume of fluid) method was applied to track the flow surface.Comparisons of the velocity distributions under the two conditions showed that the installation of guiding bafflers downstream the surface aerators can increase the velocity at the ditch bottom,and the vertical velocity distributions in the oxidation ditch becomes more uniform,which will help to prevent sludge deposit at the bottom of oxidation ditch and have obvious effect on the time prolongation for the liquid-gas mixture.关键词：oxidationditch;numericalsimulation;guidingbafflers;turbulence
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发布时间：2023-11-14 - 摘要：Abstract:The series of model experiments were conducted by changing rain intensity and rainfall duration, and the relationship between the high intensity sediment transport in the gully due to rainstorm and the accumulation body in the confluence was studied experimentally in laboratory.The results showed that the evolution of the accumulation body synchronized with the location of main-stream in the gully.There was a positive correlation between the times of the main-stream changing and the rain discharge.In contrary,there was a negative correlation between the times of the main-stream changing and the rain intensity.The length and thickness of accumulation body increased with the increase of rain discharge.The gradient of vertical sections was significantly affected by flow structure nearby accumulation bodies.In general,the gradient of section was lowest in all of vertical sections.Meanwhile,either section was largest. In addition,because of the evolution of accumulation body,the section was a multiple accumulation structure. Finally,the longitudinal profile of accumulation body was wedge,and the shape of transverse profile was multi-peak.关键词：rainstorm;steep gully;gigh intensity sediment transport;accumulation body;confluence zone
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发布时间：2023-11-14 - 摘要：Abstract:Taking the Yunying underground energy storage of layered salt rock in Hubei province as a demonstration project,a similar simulation experimental platform of concentration field in construction period of salt caverns was established based on the similar theory of dimensional analysis.The concentration distribution in salt rock cavity with interlayer in construction period was studied for providing the theory basis of shape optimization.The results showed that when there are interlayers existing in the cavity,the concentration of brine is subjected to exponential distribution with time,which is the same as that without interlayer.Except for boundary layer,the concentration of brine around the interlayer in the same level is uniformly distributed.When the cavity has a single short interlayer which located over the water inlet,the concentration of brine around the interlayer will decrease compared with the cavity with no interlayer,but the concentration of brine which below the water inlet will keep un-changed.When the single short interlayer is located under the water inlet,the concentration of brine which over the interlayer will increase and the concentration gradient around the interlayer in vertical direction will decrease. When there are two interlayers existed in the cavity,the concentration of brine around the interlayer will change accordingly,and the cavity’s concentration will increase integrally. Lengthening the interlayer,the trend of the brine’s concentration with depth will stay the same, but it will increase the concentration of the cavity.关键词：salt rock;interlayer;concentration;similar simulation;shape optimization
- 2073
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发布时间：2023-11-14 - 摘要：Abstract:The creep property of the salt rock is an important determinant of deep underground repository of energy for long-term operation.New fractional derivative creep model was built by using the Abel dashpot and Abel dashpot with strain triggered based on the definition of fractional derivative. Through over 4 months’ experiment,creep curve for the whole process was got.Based on the experimental data of the salt rock creep,fitting analysis on parameters of fractional derivative creep constitutive model was provided and the parameters of the model were determined.In addition, comparing the fractional derivative creep model with the Nishihara model, it is found that fractional derivative model is in better agreement with the experimental data.The model not only overcomes the drawback that integer-order creep model is not in good agreement with the experimental data at the primary creep stage, but also reflects the whole process of creep characteristics of salt rock.关键词：salt rock;fractional derivative creep model;Nishihara model;the Abel dashpot
- 2804
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- 5
发布时间：2023-11-14 - 摘要：Abstract:To testify whether large eddy simulation method can be applied to simulate the hydraulic characteristics in stilling basin with shallow-water cushion(SBSWC),a systematic comparison of calculation and experiment was conducted. It was shown that the flow regimes,velocity fields and pressures distributions obtained from LES are in good agreement with the experimental data, which indicated that it is reasonable to use LES to simulate the complex flow characteristics in SBSWC.关键词：stilling basin with shallow-water cushion;large eddy simulation;flow state;time average pressure;fluctuating pressure
- 2653
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发布时间：2023-11-14 - 摘要：Abstract:In order to study of the unstable phenomena due to additional inertia forces during the runaway transients of hydropower units,the 3D simulation of the runaway transients in the whole passage of a bulb turbine was presented.The histories of pressure pulsation,rotating speed,torques,forces,and flow patterns were analyzed intensively.The results showed that the turbine blades endure asymmetrical alternating forces and the vortex rope structure in the draft tube is more complicate with breaking vortex rope because the gravitational water pressure gradient is apparent in this situation. In runaway process,the increasing rotational speed enhances significantly the flow impacts on blades,flow separations,and vortex rope intensity,causing severe pressure fluctuations.关键词：bulbturbine;runawaytransient;pressurepulsation;gravitationalforce
- 2386
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发布时间：2023-11-14 - 摘要：Abstract:Some hydropower stations were built on soluble rocks such as carbonate and the flow field,chemical field and solid properties around a dam site were changed,which may have adverse effect on the operation.Two factors,surface reaction and mass transfer,were thought to control the dissolution process.Based on this,a model of coupled fluid flow and chemical dissolution in a single fracture was built up and solved.And the results showed that the dissolution front is not a plane,but somehow like wormholes.And the aperture along the fracture becomes narrower.Although the flow through the fracture becomes larger,the amplitude was small.And the range and growth rate of equivalent hydraulic aperture are much smaller than actual average aperture.The distribution of Ca2+concentration is similar to the aperture,while the reaction rate at upstream is much faster than the one at downstream.And along the whole fracture it is controlled by surface reaction initially. As the dissolution processing,it turns to mass transfer control near the inlet,while it remains surface reaction controlled near the downstream.关键词：limestone fracture;model of coupled fluid flow and chemical dissolution;surface reaction rate kinetic control;kinetic mass transfer control;numerical simulation
- 2415
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发布时间：2023-11-14 - 摘要：Abstract:The rotary flow spillway tunnel with blocking was proposed for meeting the requirement of energy dissipation in high dam.The hydraulic characteristics of rotary flow in tunnel with different blocking,such as flow pattern,discharge,wall pressure,cavity diameter,rotational flow angle,and velocity were studied by experimentation,and then the velocity distribution was analyzed by quasi-free-vortex hypothesis.The results showed that the possibility of cavitation would decrease with the increase of wall pressure due to the blocking, and the energy dissipation would increase significantly with the increase of rotational flow angle and intense turbulence flow in the blocking.The disadvantage was that the discharge would be decreased.By the analysis of flow mechanism and measured velocity,the tangential velocity distribution along radial direction was studied by quasi-free-vortex hypothesis.The relation among wall pressure,rotational flow angle,cavity diameter,discharge and parameters of tangential velocity distribution was established, and the axial velocity expression was built.Then the expressions were verified and characteristics of flow motion were proved by experimentation.The results could provide references for the research and application of the tunnel.关键词：rotaryflowspillwaytunnelwithblocking;velocitydistribution;quasi-free-vortex;axialvelocity
- 3211
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发布时间：2023-11-14 - 摘要：Abstract:In order to obtain formulas of creep stress redistribution on composite beams,constitutive relations of concrete creep were established by taking an axisymmetric composite cross section subjected to moment and axial force as a research object, and the differential equations of moment and axial force redistribution with internal forces distribution method were deduced.Then practical approximate solutions were acquired through effective simplified conditions to avoid complicated calculations of exact solutions. Its accuracy was verified through an example finally.The results showed that the error between approximate and exact solutions was very small,which could achieve reasonable calculation accuracy.Concrete creep was a significant influence on a long-term stress characteristic of composite beams which must be put enough attention in computation.The internal forces distribution method can be used in a wide range as long as internal forces are converted to moment and axial force in the section neutral axis regardless of applied loading type, whether statically determinate or indeterminate structure.关键词：steel-concrete composite beam;creep;stress redistribution;internal forces distribution method;practical calculation
- 2135
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发布时间：2023-11-14 - 摘要：Abstract:Axial compression ratio is a critical factor which affects the structure’s ductility and resistance to progressive collapse.Through 12 specimens of T-shaped steel reinforced concrete columns under cyclic load loading test, the failure mode,hysteretic characteristics and ductility performance were investigated.The axial compression limit of T-shaped steel reinforced concrete columns was derived by the balanced failure method.The result indicated that T-shape steel reinforced concrete column possesses a good ductility performance,the specimens with λ=2.5 failed in bending, whereas the specimens of shear-span ratio λ=2.0 failed in shear compression under cyclic load.Based on the relation between the experimental and the design axial compression ratio,the axial compression ratio limit of steel reinforced concrete columns with T-shape in different seismic level was proposed,which could provide a reference for seismic design.关键词：steelreinforcedconcretecolumn;lowcyclicloadingtest;ductilityperformance;axialcompressionratiolimit
- 2086
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发布时间：2023-11-14 - 摘要：Abstract:In order to simulate wind-bridge interaction and study bridge flutter instability effectively,a lattice Boltzmann analysis of fluid-structure interaction (FSI) problems was presented.The flow around a rigid fixed bridge cross-section was modeled by large eddy simulation (LES) through incorporation of dynamic sub-grid-scale (SGS) model in multiple relaxation time lattice Boltzmann method(MRT-LBM).The time discretization of the structural dynamics was performed using Runge-Kutta method. The loosely-coupled partitioned algorithm was accomplished by updating fluid-structure interfaces via moving boundary technique of lattice Boltzmann method. In the end, the Great Belt East Bridge was investigated to study its flutter instability using self-developed codes. A good agreement was found between the simulation and the existing results regarding the critical flutter speed of Great Belt East Bridge. Moreover, the study showed that the present methodology has a well prediction for the onset of flutter instability.关键词：flutter;fluid-structureinteraction;latticeBoltzmannmethod;largeeddysimulation;criticalflutterspeed
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发布时间：2023-11-14 - 摘要：Abstract:The termination of the initialized two variable homogeneous linear loops was studied. By analyzing the property of the set NTcomposed of all nonterminating points, the problem about the construction of NTwas converted to a class of nonlinear optimization problem.More importantly,by verifying whether or not the initial input of such loops lies in set NT,the termination of the initialized two variable homogeneous linear loops can be checked completely.关键词：trustworthysoftware;looptermination;optimizationproblem;QEPCAD
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发布时间：2023-11-14 - 摘要：Abstract:A fusion framework based on compressive sensing theory was proposed under the premise of guaranteeing fusion quality and reducing time-consuming.A fusion algorithm for visible image and infrared image was proposed based on compressive sensing and nonsubsampled contourlet transform.The highpass subbands attained by NSCT are the sparse representation of the source image.The sparse data was transferred to compressed domain by nonlinear mapping,and then the fusion operator was implemented in this domain.Finally,the fused image was attained by the optimization of the problem for exact reconstructing image.The calculation efficiency of algorithm was improved due to the fusion in compressed domain and the reduced the amount of data. Therefore,the algorithm is effective for improving the efficiency of fusion algorithm and the application of airborne real-time.关键词：imagefusion;compressivesensing;sparserepresentation
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发布时间：2023-11-14 - 摘要：Abstract:In order to enhance the complementary advantages by registration and fusion of virtual and real image, a precise registration algorithm by edge feature and global optimization was proposed and the problem was transformed to a classical multi-modal image registration problem. At first, initial registration was achieved by inertial navigation system(INS) instruments. Then the 3D model and visual image edge structure similar with human vision was extracted by the edge algorithm based on phase congruency model. Finally the global optimal parameter with respect to maximal registration value of space transforming model was calculated by simulated annealing algorithm. 4 groups of experiments result showed that this registration method can make full use of the similar edge structure between 2 images; and simulated annealing algorithm can achieve the better parameter for registration transform. The experiments result also indicated that these multi-modal pairs are registered with enough accuracy.关键词：virtualandrealregistration;multi-modalimage;imageregistration;simulatedannealing;phasecongruency
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发布时间：2023-11-14 - 摘要：Abstract:A fully automatic point cloud data registration algorithm was proposed to disorderly point cloud with no additional information other than coordinates of measured points.In the algorithm,the normal vector and curvature were first estimated according to its neighbor points and Least-Squares approximation. Secondly,the EGI and CEGI were calculated.Then, the calculation of Euler angles of rotation through spherical harmonic functions and the translation according to Fourier transform were completed.With the initialization of the former results,the iterative closest point algorithm leads to perfect registration.Experimental results indicated that this kind of registration algorithm has a better effect.关键词：disorderlypointclouddata;normalvector;curvature;EGI;3Drotationgroups;Fouriertransform
- 2016
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发布时间：2023-11-14 - 摘要：Abstract:To meet the application requirement of proxy blind sign,a new certificateless proxy blind signature scheme based on paring was presented.Through the pre-calculation of the parameter which is published as one of the system parameters,the new scheme does not require any pairing computation in the sign step.The comparison with other schemes in the literature showed that it is more efficient has advantages in practical application.The scheme was proved to be existentially unforgeable against Type Ⅰ or Type Ⅱ adaptively chosen message and identity adversaries in random oracle model,under the bilinear Diffie-Hellman assumption.关键词：certificateless;proxyblindsignature;randomoraclemodel;bilinearpairings
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发布时间：2023-11-14 - 摘要：Abstract:Taking into account the reliability of protein-protein interaction (PPI) network, an uncertain network was constructed and a novel method named essential proteins identification based on uncertain networks (EPU) was developed to identify essential proteins from the uncertain network. The concept of expect density was used to decide whether a subgraph can be represented as an essential module for essential proteins identification. Proteins were ranked through their probabilistic frequency appearing in these predicted modules. Then the ranking scores of these proteins were used to judge whether a protein is essential. Experimental results showed that the EPU algorithm outperforms other essential proteins prediction algorithms and is a special method which is different from others. The results indicated that the theory of uncertain data management is useful for the improvement of robustness in protein-protein interaction networks.关键词：uncertainnetwork;essentialproteins;protein-proteininteraction;prediction
- 1868
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发布时间：2023-11-14 - 摘要：Abstract:In order to solve the problem of the low efficiency caused by the traditional query expansion retrieval methods，a novel approach based on extension knowledge was issued with a novel rhomb reasoning method by using extension theory. By introducing the extension relationship between concepts with extension reasoning, the proposed method can relationally solve the detection problem of sensitive information. For illustration, an example was utilized to show the feasibility of the method in solving detection problem with concept query expansion method. Empirical results showed that the proposed method has a good performance on detection of short text which has a low degree of description, and could reduce the omission of relative information. The proposed method can improve the detection precision and recall of the document sensitive information．关键词：shorttext;extensionknowledge;sensitiveinformation;queryexpansion;knowledgebase
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发布时间：2023-11-14 - 摘要：Abstract:Aim at the characteristics of complex network in power systems,and in order to solve the problem of equivalent parameter that is completely unknown for external network,an equivalence method based on the measurement information of the boundary nodes was proposed to equivalent the two-port external network.The measurement information of the power flow calculation includes the voltage vector of boundary nodes,active power and reactive power.The equality constraint relationship between the equivalent models of the external system and the boundary node information was adopted to estimate the equivalent parameters of external system model by using the numerical iterative.Through comparing the short circuit level,power distribution and dynamic performance for IEEE 14-bus system,the correctness of the proposed equivalent method and its engineering practicability were verified.关键词：equivalentsimplification;boundarynodes;measurementinformation;powerflowcalculation
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发布时间：2023-11-14 - 摘要：Abstract:The wind’s randomness and volatility bring great difficulty to the wind accommodation and grid security with the gradually increasing wind power, and network loss’s negligence in the dispatch model may lead generating power shortage. Based on these issues the intra-day economic dispatch rolling revision model based on the net loss iteration was established. The rolling revision model regulated the scheduling power according to the latest forecast information. The network losses was considered in the loss iterative process, then the economic dispatch process was done. The AC power flow was calculated and the line flow security was checked in each iteration. Afterwards, the system losses were updated.Moreover, the regulation strategy based on the relaxation unit power limitation and adding additional constraint was built to solve non-convergence the in the dispatch process and line overload problem. Finally, a numerical example simulation verified the effectiveness and correctness of the proposed model.关键词：economicdispatch;windpower;securityconstraint;lossiteration;rollingrevision
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发布时间：2023-11-14 - 摘要：Abstract:Because the accuracy of the traditional minimum voltage drop method used to commutation failure is not high enough, a new commutation failure criterion was proposed. In order to clarify the effect of the fault impedance on the commutation failure, the mathematical relationship between the fault impedance and the commutation voltage was analyzed in detail by two methods of the sensitivity analysis and node impedance matrix. According to the two commutation voltage analysis methods, the critical fault and critical coupling impedance solving methods of local and simultaneous commutation failures were given, respectively. The simulation results showed that the accuracy of the new commutation failure criterion is very high, and two kinds of commutation voltage expressions deduced by the two analysis methods of commutation voltage have also a certain accuracy. At last, the effects of AC fault, load characteristics and system parameters on the commutation voltage were analyzed, and some useful and instrumental conclusions were obtained.关键词：multi-infeedHVDCsystem;commutationfailure;commutationvoltage;criterion;ACfault;influencingfactors
- 2259
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发布时间：2023-11-14 - 摘要：Abstract:An adaptive sliding mode control strategy for gas feeding system of solid oxide fuel cells (SOFCs) was presented.By stabling the pressure of reaction gas to make the pressures of hydrogen and oxygen equal to prevent the electrolytes from damage,the life span of SOFCs is able to be prolonged.A dynamic model for the gas partial pressures of the SOFCs was built with the consideration of internal parameter perturbation and external uncertain interference of the system.An adaptive law,with forgetting factor and modified algorithm,was designed to estimate the upper bound of disturbance while it was unknown.In order to reduce the chattering of sliding mode controller,the sign function was substituted by saturation function in a defined bound near the sliding mode surface.The simulation results showed that the proposed controller has good performance in inhibiting unknown disturbance and eliminating chattering,ensuring that the pressure difference between hydrogen and oxygen could keep in zero while load current has changed.关键词：solidoxidefuelcells;partialpressures;adaptiveslidingmodecontrol;forgettingfactor;bound
- 2527
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发布时间：2023-11-14 - 摘要：Abstract:A nonlinear adaptive observer was proposed for a class of Lipschitz nonlinear systems with unknown parameters and output uncertainty.Under the condition that the output uncertainty is Lipschitz，the structure of the observer was given.The observer gain matrix and the adaptive law of parameter estimation were selected based on calculation of Riccati equation and linear matrix inequality (LMI).The uniform boundedness of the estimation error of the system state was shown by Lyapunov method.The simulation results demonstrated the effectiveness of the proposed adaptive observer.关键词：outputuncertainty;Lipschitz;adaptiveobserver;Riccatiequation;matrixinequality
- 2802
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发布时间：2023-11-14 - 摘要：Abstract:Based on the physical and chemical properties of sludge and construction waste, construction rubbish, sludge or river sediment were used as base stock to prepare a well kind of waterproof insulated high strength and lightweight foaming ceramic plate, and the effects of firing condition, solid phrase including aggregate and glass fragment, animal foaming agent, bentonite on the foaming tendency and properties such as water absorption rate, porosity, density and compressive strength were explored. The results showed that under the optimal formula and firing conditions including the combined aggregate of construction waste and sludge of 70%, glass fragments of 20%, animal protein foaming agent of 5%~7%, bentonite of 5%~7%, and under preheating temperature of 700 ℃, preheating time of 40 min, sintering temperature of 1 200 ℃, sintering time of 30 min, the best foaming ceramic property was obtained such as the water absorption rate of 1.62%, porosity of 70.12%, the compressive strength of 5.12 MPa, the bulk density of 0.48 g/cm3. The product performance is better than the relevant national standards.关键词：foaming ceramic plate;animal protein foaming agent;sludge;construction waste;foaming
- 2241
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发布时间：2023-11-14 - 摘要：Abstract:The influence of slotting on the mechanical properties and transmission performance of gear teeth of filtering gear reducers was studied through finite element method.According to the comparative results of different slot shapes,it is found that straight slot has very good effect on mechanical properties of the gear tooth.Then the influence of slot depth,pore size,stress release hole and the chamfer size was analyzed, cases with different applied loads were also simulated.Finally,the results showed that the straight slot on Filtering Gear Reducer when its depth is three times bigger than the modulus of the teeth, the radius of stress release hole and the chamfer are both ten times bigger than the pore size，and pore size is smaller than ten percent of the modulus of the teeth, can effectively improve the mechanical properties of the tooth and reduce the vibration caused by gear meshing.关键词：slotting on the gear teeth;slot profile;contact stress;bending stress;finite element method
- 2096
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发布时间：2023-11-14 - 摘要：Abstract:To mill external circular arc segment efficiently,a special milling machine for flywheels was designed based on double-spindle double-station four-turntable,which used the longitudinal feed of sliding table and circular feed of workpiece turntable to form cutting trajectory in polar coordinates,and used the rotary motion of station turntable to constitute double stations of processing and handling，each of which could mill two workpieces at the same time.Aiming at the symmetric layout of double-spindle and vibration produced easily by double cutters,the modal and harmonic responses of the spindle system were analyzed on ANSYS in order to optimize the double-spindle structure.A new linear interpolation algorithm in polar coordinates was described,which implemented the continuous processing of external circular arc segment.Processing experiment showed that machining accuracy is 0.02 mm,surface roughness is Ra 0.8,machining efficiency is 300～400 /h.关键词：double-spindle;dynamic characteristics;polar coordinate;circular arc segment
- 2538
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发布时间：2023-11-14 - 摘要：Abstract:In order to improve the utilization of jet energy,an experiment was conducted with a kind of polymer(PAM) added into the injection abrasive water jet for cutting.The roughness of machined surface was measured by mitutoyo surftest to evaluate the influence of PAM concentration on the surface quality.The results showed that the roughness of machined surface shaped by abrasive water jet with PAM slightly decreased at first and then remarkably increased with the increase of cutting depth.Meanwhile,the roughness formed by abrasive water jet without PAM had a similar tendency.Furthermore,it was worth noting that the roughness was significantly reduced when the PAM concentration arrived at 400 mg/kg,where the drag reduction effect was remarkable.When the PAM concentration came up to 600 mg/kg,the optimal surface quality was obtained because of the occurrence of the maximum drag reduction effect.At that point,the viscoelastic stress of polymer showed good match with the energy level of most small vortexes.In addition,the effect of PAM concentration on the roughness became more and more remarkable with the increase of standoff distance or feed rate,such behavior was of great importance in optimizing the operating parameters of water cutter so as to improve its efficiency.Also,the kerf width of workpiece along cutting depth gave a minimum change at the PAM concentration of 600 mg/kg.It was concluded that the appropriate PAM concentration increased the energy of the jets,and greatly improved the cutting ability.关键词：abrasive water jet;high molecular polymer;drag-reducing;Kerf width;surface roughness
- 1948
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发布时间：2023-11-14 - 摘要：Abstract:Internal defect detection plays a key role in quality assurance of magnetic tile. In order to solve the issue of internal defect identification of magnetic tile using human auditory,bispectrum was used to analyze the acoustic signal generated in a drop impact test of magnetic tile whose internal defect was known.The analysis indicated that internal defect can affect peak distribution of bispectrum. In accordance with this rule,a method based on three-slice analysis of normalized bispectrum was presented for internal defect detection of magnetic tile. With this method,firstly,the three slices were extracted along the specific directions of normalized bispectrum.Secondly,each slice was divided into several frequency regions and all regions were classified,according to the mapping between peak distribution and internal defect.Thirdly,by comparing and calculating the maximum peak of the dissimilar regions,the threshold value was established to distinguish internal defect.The effectiveness of this method was assessed by a verification test at last.The test result showed that the identification accuracy achieved over 97%, which demonstrated that the bispectrum analysis could be applied to the acoustic inspection for internal defect of magnetic tile.关键词：bispectrum;acousticinspection;magnetictile;internaldefect
- 1921
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发布时间：2023-11-14 - 摘要：Abstract:History design scheme is helpful in welding fixture design characterized by complexity and individuation.To improve the scheme design efficiency of welding fixture, a multi-layer case reasoning method based on the extension reuse of design knowledge was presented.Welding station information model based on knowledge reuse was introduced by analyzing various fixture design features,and the repository of fixture design based on basic element model was established. Then the extensible model of knowledge reuse was also built.With the use of dopting multi-layer case based reasoning method and calculating the similarity based on basic element feature,the best case was obtained by retrieving the similar welding station composed by shape feature and assembly feature from inside out. Finally, this method was proved to be effective through the verification of the study on an rear floor assembly.关键词：weldingfixture;basicelementmodel;weldingfeature;extensionreuse;multi-layercasereasoning;similarity
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发布时间：2023-11-14 - 摘要：Abstract:The issue of smoothing sharp corners between consecutive small line blocks in high-speed machining was discussed.According to the characteristics of the rational quadratic Bézier curve,the vector model of conic section transition was constructed.The formulas of the maximum contour error and the maximum curvature of conic segments were derived.Subsequently,a corner curve transition interpolation algorithm based on conic section was proposed. On the basis of this algorithm,the conic section type was defined by the weight which could satisfy the prescribed contour machining accuracy and the adjacent line segment length.At the same time,the maximum velocity limited by chord error,interpolation distance and dynamic response of machine tool was calculated.Moreover,an improved look-ahead method, which could adjust the corner velocity between two trajectories by modifying the weight of the transition curve,was presented.The comparison between the arc transition results and the conic section transition results showed that the proposed algorithm could improve transition velocity and reduce machining time.关键词：highspeedmachining;micro-linecorner;conicsection;interpolationalgorithm
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发布时间：2023-11-14
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