最新刊期
卷 45 ， 期 2 ， 2013
- 摘要：Abstract:The relationship between bed-load transport rate and flow intensity was discussed.Armoring layer destruction experiments were carried out in natural channel with clear-water scour. The results showed that dimensionless transport rate strength,corresponding to the maximum bed-load transport rate,increases with flow intensity and the increasing speed is faster than the calculated results by Meyer-Peter formula,Bagnold formula,and Engelong formula. Using the same forms of Meyer-Peter formula,through regression the relationship between dimensionless transport rate strength,corresponding to the maximum bed-load transport rate,and flow intensity during the process of clear-water scour and armoring layer destruction was established.关键词：bed-load transport rate;clear-water scour;armoring layer destruction;flow intensity
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发布时间：2023-11-14 - 摘要：Abstract:Sediment transport is one of the basic issues in the field of river dynamics.The sediment transport nature in fully mobile bed compound channels was experimentally studied under the action of clear water and then the method for modeling the sediment transport rate in the type of channels was proposed.The experimental results showed that the sediment transport rate first increases and then decreases with time.The median diameter of sediment first rapidly and then slowly increases with time,and finally approach the median diameter of the original bed material.According to the motion nature of sediment transport,the computational method for sediment transport rate in the type of channel was proposed.Meanwhile,the sensitivity analysis of parameters in the proposed method was undertaken.The computed results showed that the method can be capable of modeling the sediment transport in the processes of clear-water action.关键词：fully mobile bed;compound channels;clear-water scour;motion nature of sediment transport;computational method for sediment transport rate
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发布时间：2023-11-14 - 摘要：Abstract:In steady uniform flows with different particle diameter,specific gravity and flow slope,ten runs of experiments with bed-load particles were performed using a three dimensional particle tracking velocimetry (3D PTV) technique,and then the turbulence velocity characteristics of bed-load particles were analyzed statistically.The experimental results showed that the longitudinal turbulence intensity of bed-load particles increases with the decrease of diameter and the increase in slope.In the near wall region,the vertical and transverse turbulence intensities showed the reverse law with the longitudinal.The specific gravity has inconspicuous effect on the turbulence intensities.关键词：particle diameter;specific gravity;flow slope;turbulence intensity
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发布时间：2023-11-14 - 摘要：Abstract:Bed-load transport process over steep slope is of large fluctuations.This kind of fluctuation widely exists over different time scales.Due to this random behavior,the stochastic model can make a better performance on the description of bed-load transport process than the deterministic one.Based on the result of the early study,an alternative method to derive the theoretical solution was provided.Compared to the early derivation,by using this method the theoretical solution can be straightforward obtained from master equation.This solution was tested well against the numerical simulation and experimental data.关键词：sediment transport;probability density function;collective entrainment;Markov processes;stochastic models
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发布时间：2023-11-14 - 摘要：Abstract:The series of overland flow experiments were conducted on flexible vegetative beds with 20 degree slopes,and the hydraulic characteristics of sheeted flows were observed for parameters such as surface velocity,flow depth,and the averaged velocity.The local head losses was also calculated.The results showed that the mechanism of flow resistance presents very obvious differences because of the effects of hydraulic jump and aeration on the overland flow around flexible vegetation.The fitting relations showed an exponential function and curve of the second degree,respectively.In addition,the surface flow velocity was made by means of dye-color method,the relationship between surface velocity and averaged velocity was discussed,and the revised coefficient of 0.23 with the distributions of flexible vegetation was obtained.关键词：overland flow;flexible vegetation;flow resistance;local head losses
- 3160
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发布时间：2023-11-14 - 摘要：Abstract:In order to study the deteriorating mechanism of the structure performance, the resistance of deteriorating structures was described by Gamma distribution which has a character of independent increment, the changing process of load was described by Poisson stochastic process and Bernoulli stochastic process respectively, then, the load-resistance double stochastic process system was established. Also, based on the conception of crossing rate, the new time-varying reliability analysis method for the engineering structure performance was put forward and the expression was calculated. Analysis showed that the new stochastic process model can better describe the degradation of resistance and the load variation process with time, so it can provide the theory basis for the evaluation of existing structures based on the time dependent reliability theory as while as the life prediction.关键词：deteriorating structures;stochastic process;time-varying reliability;probabilistic model
- 3292
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发布时间：2023-11-14 - 摘要：Abstract:The strain resistance effect of smart concrete under triaxial compression was studied,and compared with the result measured under uniaxial compression.The results showed that during elastic stage of deformation,the axial resistance decreases with the increase of axial load,while it increases with the increase of confining pressure.The axial strain is the direct and fundamental cause for the change of axial resistance.Comparing with uniaxial compression, the change of axial resistance also has three stages under triaxial compression: reversible induction stage,balance stage and rapid increase stage,but the reversible induction stage and balance stage are relatively long.The gauge factor of smart concrete under triaxial compression decreases,but owns better linearity.关键词：smart concrete;triaxial compression;strain resistance effect
- 2806
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发布时间：2023-11-14 - 摘要：Abstract:In order to evaluate the effect of land use change on soil erosion process,a mathematical model was developed for simulating runoff generation and sediment transport processes on different slope lands.This model was comprised of two modules:the kinematic-wave equation for overland flow and a sediment transport formula.The measured runoff generation and sediment transport data of bare land,grassland,cropland,scrubs land and young forest land were used for model validation and the simulating values were in good agreement with the measurements.Then the characteristics of runoff generation and sediment transport under different land use scenarios were predicted using the model and the results showed that soil erosion could be greatly controlled on 5-year-old forestland or grassland with coverage more than 60% under the normal rainfall in the loess plateau,and light erosion occurres in the middle and lower part of the bare land with the gradient less than 15°.Only the 10-year-old forestland could provide a good erosion control effect while the effects of grassland and bare land are limited under the once in ten-year rainfall. Both grassland and forestland should be cooperated in combating erosion by taking the advantages of the faster effect of grassland for low intensity and short duration rainfall and the more obvious effect of forestland for high intensity and long duration rains.The slope length should be strictly controlled for bare land with different gradients.关键词：land use pattern;kinetic wave;sediment transport formula;runoff generation and sediment transport processes;model application
- 3019
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发布时间：2023-11-14 - 摘要：Abstract:Due to the unique modeling of butterfly-shaped arch bridge,the nonlinear mechanical behavior is difficult to master compared with ordinary arch bridges,and the traditional design method which is not fully considered in nonlinear influence is not applicable.On the basis of self-compiled program, the nonlinear property and its influencing factors were comprehensively analyzed according to butterfly -shaped arch bridge.The results showed that the nonlinear coefficients of main cable forces are inversely proportional to the values of cable force under uniform load.The main cable sag has most influence on nonlinear cable forces.The beam-column effect of arch-rib elements accounts for small percentage in total effect for the main cable forces.When the dense cable system is adopted,the stay cable forces are not reliable if the cable sag is not considered.The nonlinear factors have less influence on cable forces when the eccentric load is close to cable plane.When the main cables are tilted,the own nonlinear effect is decreased,however,the nonlinear effect of stay cables and subsidiary cables is increased.关键词：bridge engineering;geometric nonlinearity;increment iteration method;butterfly-shaped arch bridge;cable sag
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发布时间：2023-11-14 - 摘要：Abstract:Based on the test of eight masonry walls under low cycle reversed loading,the seismic performances of strengthened unreinforced masonry walls by BFRP were analyzed from multi-angle,mainly including the hysteretic curve,energy dissipation capability and damage.Then the design formula of the BFRP strengthened damaged and non-damaged masonry walls was given,and the results showed that the theoretical values are in good agreement with the experimental results.The experimental results showed that the BFRP strengthening technique can effectively postponed the development of cracks,increase the capacity of deformation and load-carrying,and the masonry walls’integrity and energy dissipation properties can also gain a significant improvement.关键词：BFRP;reinforcement;hysteretic property;seismic performance;masonry
- 3046
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发布时间：2023-11-14 - 摘要：Abstract:Based on the uniaxial and triaxial compression mechanical tests and the cyclic loading tests in the post-peak period of Benxi limestone,its strength and deformation with different confining pressures,processes of failure and cyclic loading,and failure types in different stress were studied.The results showed that in the post-peak but the strength has not decreased to the residual strength period,the elastic modulus is equal to the elastic modulus in pre-peak,and the new peak stress will be lower than the stress of starting unloading.In the period that the strength decreases to the residual strength,the strength will not decrease with the cyclic loading.It is viable to adopt the method that comparing circumferential elastic strain with circumferential strain of peak to judge the failure type of Benxi limestone.There are two failure types that are tensile failure and shear failure for Benxi limestone in different confining pressures,and the relation between rock damage and failure should be considered in founding the constitutive model.Based on this,circumferential strain and shear strain were selected as the distribution variables in the new statistical constitutive model which describes the brittle stress-drop and relation between stress and strain in the post-peak period very well.关键词：rock mechanics;tensile failure;shear failure;brittle stress-drop;constitutive relation
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发布时间：2023-11-14 - 摘要：Abstract:Geddes’s solution is one of a comment approach to estimate the settlement of subsoil of pile foundation.In order to obtain more precious results,a modified Geddes’s solution was performed as the assumptions that the end resistance uniformly distribute on the pile tip and the side resistance,and the component force of uniform and linear variation distribute on side surface of pile shaft.The formulas of induced stress due to side resistance and end resistance of circular cross-sectional pile were obtained and calculated by double integration.The results of comparative analyses between Geddes’s solution and modified Geddes’s solution showed that the differences between the two methods increase with the increase of pile radius.With pile radius varying from 0.2 m to 3 m,the results disparity between Geddes’s and modified Geddes’s solution are limited in 20%,exceeding to 140%,and closing to 40% due to end resistance, uniform side resistance,and linear variation of side resistance, respectively.The results estimated by Geddes’s solution is greater than reality. Compared with Geddes’s solution,the settlement of the modified Geddes’s solution agrees well with that of finite element analysis.Therefore,the modified solution is more reasonable for designation and application.关键词：Geddes’s solution;induced stress;side resistance;end resistance;settlement
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发布时间：2023-11-14 - 摘要：Abstract:To securely employ fingerprint-based identity authentication in open network, private fingerprint data of a user and a server must be protected.A novel algorithm was presented to perform the minutiae matching while privacy of the two parties was preserved. In the proposed algorithm,a sequence consisting of the template of the server and query minutiae of the user was firstly sorted by oblivious sorting algorithm.Then,all the neighbor elements of the sequence were tested whether they are equal.Finally, several adders were used to compute the quantity of matched elements. The proposed algorithm was crystallized by using garbled circuits and some approaches were taken to optimize the structure of circuits. Experiment results showed that the proposed scheme is capable of real-time authentication.关键词：minutiae;garbled circuits;privacy protection;oblivious sorting
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发布时间：2023-11-14 - 摘要：Abstract:When metallic implants exist in human bodies, there will be severe metal artifacts which can obviously affect the clinical diagnosis. To deal with metal artifacts with acceptable imaging time, a fast marching method was used to solve the Eikonal equation and the inpainting order was obtained for projection data.By designing the corresponding weighted function and introducing structure tensor to construct the coherence transport field of the sinogram which was used to determine the coherence strength, the inpainted projection data were calculated.The experiment results demonstrated that this method not only has a good metal reduction performance as two-dimensional correction methods, but also is fast close to one-dimensional interpolation methods.关键词：CT metal artifact reduction;coherence transport;fast marching method
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发布时间：2023-11-14 - 摘要：Abstract:The conflict detection algorithm based on the three dimensional coordinate system was proposed to treat the flight conflict problems arisen from the development of Air Traffic Control in China. First of all, based on the features of the flight path, the conflict probability was solved after time integrating flight path and the efficiency of continuous solving conflict probability was improved. Then the flight conflict of the change of flight level during free flight in the three dimensional coordinate system was took into consideration. Plenty of experiment was simulated by using the method of Monte Carlo. The feature of track error and precision parameter was analyzed, which shows the effects of the track error and precision parameter on conflict probability and false alarm. The experiment result proved the availability and practicability.关键词：air traffic management;conflict detection;conflict probability;trajectory error
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发布时间：2023-11-14 - 摘要：Abstract:In recent years, feature and opinion classification of Chinese product review is one of the most important research fields in Web data mining. A well-defined specification on data annotation for product named entities, features, opinions and boundaries was proposed and a hybrid tag representation was designed.By integrating linguistic features and POS features into automatic learning, a novel two-level Hierarchical HMMs (HHMMs ) framework was put forward. The HHMM-1 and HHMM-2 algorithms were advanced to identify features and opinion entities automatically. The experimental results showed that two-level HHMM works in a mutual complementation way, which makes the recall and F-score of our approach obviously outstanding.关键词：Web data mining;feature and sentiment classification;tagging specification;two-level HHMM
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发布时间：2023-11-14 - 摘要：Abstract:In order to deal with the expansibility and fault tolerance of the cloud storage system, expandable encoded cluster storage architecture with low price and low data redundancy was presented. The program associated with the file block encoding technology was introduced to build the high-availability clustered storage system, which was able to tolerate triple simultaneous storage node failures in any erasure pattern. The system had the optimal storage efficiency and the remarkably fault-tolerant capability. At last, the theoretical analysis and the test of the cloud storage system were introduced in detail, and an intensive performance evaluation study on it was performed.关键词：array code;cloud storage;data placement;decoding algorithm
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发布时间：2023-11-14 - 摘要：Abstract:To study the problem of reliability of software in program design,the termination of program was discussed While x∈Ω do{x:=f(x)}end under the condition that Ω is union of finite mutually disjoint closed intervals. It was proven that the termination of such loops under some definite conditions can be determined by the existence of period orbits. The necessary and sufficient condition of the non-termination for such programs under definite conditions was discussed and corresponding algorithms were given. In addition, applying Brower fixed point theorem and the theory of convex analysis, the conclusion of termination of linear loops when loop condition Ω is union of finite mutually disjoint closed convex sets in Rmwas given.关键词：nonlinear loops;linear loops;termination analysis;periodic orbit
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发布时间：2023-11-14 - 摘要：Abstract:In order to improve transmission rate, and make full use of spectrum resources, the graph theory algorithm was applied firstly to allocate rapidly spectrums (channels), and then the channels were optimized by game theory algorithm. Simulation results showed that the spectrum resources could be fully utilized. Under power transmission constraints, the utility (rate) of cognitive users is improved by using joint spectrum allocation algorithm, and the power is distributed reasonably. The simulation verified that joint algorithm based on graph theory and game theory is effective.关键词：graph theory;game theory;cognitive radio
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发布时间：2023-11-14 - 摘要：Abstract:A controlled islanding method based on the recognition of the end of power flow path was proposed to solve the roblem of system insecurity caused by low voltage of system buses which are near the system partition surface. In addition, the problem caused by bus voltage was considered. The inappropriate network structure was demonstrated that it is the root of poor condition of bus voltage, and the relationship of structure change and bus voltage stability was summarized. On the other hand, to solve the bus voltage problem, an improved method with the principle of breaking path end of power flow was proposed. The result showed that, the proposed method performs better than reactive power compensation or traditional methods in improving the bus voltage condition after controlled islanding. In this way, static security of isolated power system can be promoted.关键词：power system;bus voltage;flow path;controlled islanding;clustering algorithm
- 3364
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发布时间：2023-11-14 - 摘要：Abstract:The aluminum carboxyl methyl konjac glucomannan gel microspheres(CMKGM-Al) were prepared by crosslinking aluminum ion (Al3+) and carboxyl methyl konjac glucomannan(CMKGM). The adsorption capacity of CMKGM-Al for fluoride ion was studied. Several parameters including adsorption time, the concentration of CMKGM, the mass ratio of Al3+, microsphere size, pH, temperature, and the concentration of F-, which effect the adsorption performance, were investigated. The compound of CMKGM-Al/F- was characterized by IR spectrometry. The results showed that the adsorption equilibrium could be established about 6 hours when the temperature was 293 K. The adsorption capacity reached 47.02 mg/g, while the concentration of CMKGM was 1.2%, the mass ratio of Al3+was 2.0% and the concentration of F- was 90.5 mg/L. The thermodynamic parameters of adsorption process were calculated according to isotherms at different temperatures. The experimental data were fitted using the Freundlich equation, and it was found that the equation was applicable to the studied adsorption system. The system was a spontaneous exothermic process and the entropy of the system decreased. The low temperature was favorable for adsorption.关键词：konjac glucomannan (KGM);garboxyl methyl;fluoride ion;aluminum gel microphere;adsorption
- 2756
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发布时间：2023-11-14 - 摘要：Abstract:WO3/ZrO2 and Ce,Mn-modified WO3/ZrO2 solid superacids were respectively prepared by co-precipitation method. The as-prepared catalysts were characterized by means of XRD and Raman. The catalytic performance of the catalysts for synthetizing acetyl salicylic acid was investigated. Ce-modified catalyst showed the highest catalytic activity. Thus Ce-modified solid superacid was used as the catalyst to optimize the synthetizing technology of acetyl salicylic acid. The effects of reaction time,reaction temperature,molar ratio of reactants,as well as dosage of catalyst on synthesis of acetyl salicylic acid were investigated. The yield of acetylsalicylic acid of 94.69% was obtained under optimum reaction conditions. The catalyst is easily recovered and reused with a consistent high activity.关键词：modified solid superacid;WO;3;/ZrO;2;catalyst;acetyl salicylic acid;acetylation
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发布时间：2023-11-14 - 摘要：Abstract:In order to investigate the effects of the variables on the pervaporation (PV) performance of the hydrophilic PAA-Al2O3 composite membrane for the ethanol-water mixture,the central composite rotatable design (CCRD) was used,and the permeate flux and selectivity were chosen as the experimental responses.Regression models were developed as the functions of the graft concentration of acrylic acid,the operating temperature,and the inlet ethanol concentration.From the regression analysis of the pervaporation of ethanol-water mixture,the permeate flux was found to be significantly influenced by operating temperature and then ethanol concentration.Meanwhile,the selectivity was significantly influenced by the interaction of temperature and ethanol concentration,followed by the graft concentration of acrylic acid.In order to optimize the flux and selectivity of ethanol-water azeotropic mixtures,the desirability function approach was applied to analyze the regression model equations.For the 95%(wt) ethanol-water azeotropic mixture,the optimum graft concentration of acrylic acid and temperature were found to be 8%(wt)and 55.9 ℃,respectively;and the value of overall desirability was 0.50,which indicated that the results of optimization for the separation of ethanol-water azeotropic mixture are acceptable.关键词：hydrophilic composite membrane;PV;response surface methodology;CCRD;desirability function
- 2588
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发布时间：2023-11-14 - 摘要：Abstract:To study the preparation of nanospheres (NPs) surface-modified with glycyrrhetinic acid(GA) targeting to hepatocytes.The two GA-NH-PBLG material with the degree of polymerization of 20 and 50,were synthesized bypoly-glutamic acid benzyl ester (PBLG) with GA modified.Their structure was determined by nuclear magnetic resonance and infrared spectroscopy.The two materials were formed into NPs loaded the camptothecin via solvent evaporation method,the physical and chemical properties of the NPs were investigated by scanning electron microscopy,and the release in vitro was evaluated in vitro release study.Result shows the size of the NPs distributed between 50~300 nm and the NPs exhibited good stability against electrolyte solution.The entrapment efficiency and drug loading amount were 77.3%,82.4% and 1.4%,2.3%,respectively.The NPs had a good sustained release effect in PBS buffer solution,the drug cumulative release reached 50% in 8 days. The study laid the foundation for the preparation of NPs with active and passive double liver targeting property by the materials.关键词：target of liver;nanospheres;poly(γ-benzyl-L-glutamate);glycyrrhetinic acid
- 3107
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发布时间：2023-11-14 - 摘要：Abstract:To obtain a better understanding of relationship between structure and degradation performance of azo dye,the modified polyacrylonitrile (PAN) fiber Fe complex was used as the heterogeneous Fenton catalyst for the oxidative degradation of 28 typical water-soluble anionic azo dyes.The quantitative relationship between structure and decoloration percentage or TOC removal of the dyes was investigated by using multivariate linear regression analysis.The QSPR (quantitative structure property relationship) models were developed and then applied for predicting the degradation performance of similar azo dyes.The results indicated that the azo dyes with different structures were effectively degraded and mineralized in the presence of modified PAN fiber Fe complex.Moreover,there is a good linear relationship between molecular descriptors including MW/S(molecular weight divided by the number of sulphonate groups),the number of azo linkage,the number of aromatic rings or inorganic/organic value and decoloration percentage or TOC removal of the dyes.MW/Sand the number of azo linkage served as the most significant negative effecting factor for decoloration percentage.While the number of azo linkage or the number of aromatic ring acted as the most significant negative or positive effecting factor,respectively.The QSPR models developed are stable enough to predict the degradation performance because the relative error and correlation coefficients between the predicted and the observed decoloration percentage or TOC removal are accepted.关键词：azo dye;heterogeneous;Fenton;degradation
- 3062
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发布时间：2023-11-14 - 摘要：Abstract:The sphene doped cerium(Ca0.9Ce0.1Ti0.8Al0.2SiO5) was synthesized by solid-reaction.The chemical durability was investigated with a long-term product consistency test (PCT) by X-ray diffraction (XRD), scanning electron microscopy(SEM),and inductively coupled plasma atomic emission spectrometry (ICP-OES).The results indicated that the synthesized sphene has good chemical durability under coupling effect of hydrothermal conditions of 150~200℃, 0.476~1.554 MPa, and 5~9 pH. With the increase of soaking time, the normalized leaching rate of elements gradually decreases and maintaines at a lower level.关键词：sphene solid solution;leaching rate;chemical durability;cerium
- 2799
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发布时间：2023-11-14 - 摘要：Abstract:In order to quickly detect the interface kissing infect in composite materials, the ultrasonic infrared thermal wave (UITW) technique was researched. By established a finite element model, the UITW detection for surface micro-crack, border vertical crack, delamination and debonding damage in composite materials were numerically simulated. Then, detection experiments for delamination specimen of carbon fiber reinforced composite, fatigue crack specimen of glass fiber reinforced composite and impact damage specimen of T700/BA202 epoxy resin composites were carried out by using the UITW detection method, and the detection results were analyzed and recognized. The results showed that UITW is suitable for quickly detecting and recognizing composite materials interface kissing type damages. Micro-crack (≤0.001 m) could be detected, and the longer the crack and the bigger the crack surface, the easier the crack can be detected. The recognition accuracy for shallow defect (about 0.001 m deep) is up to 95%,and the detection error for 0.002 m crack is 13.88%. Comparing with the ultrasonic C-scan result, the error of size recognition for impact damage is 5.7%. But it has no detection result for debonding damage.关键词：ultrasonic infrared thermal wave method;composite materials;interface kissing damage;non-destructive detection;defect recognition
- 3074
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发布时间：2023-11-14 - 摘要：Abstract:According to the theory of swing movable teeth meshing,a calculation method of friction coefficient between swing movable teeth and the internal gear under elastohydrodynamic lubrication was studied by using the theories of Hertz contact and tribology. And the time-varying discipline of friction coefficient in the drive process was analyzed. Meanwhile,According to the theory of Blok flash temperature theory,the calculation model of flash temperature in a meshing period under elastohydrodynamic lubrication was built based on the calculation of the contact half-width.The distribution of flash temperature along the meshing line in the drive process was analyzed through the MATLAB programming. Sensitivity analysis of the flash temperature to relevant variables was conducted to investigate the effects of the variations of input power,speed,swing movable tooth radius and teeth number on flash temperature.The example analysis results indicated that near the inflection point of internal gear profile curve,the flash temperature is the maximum.The research result is very significant for studying the scuffing strength of tooth surface and thermal stress.关键词：swing;movable teeth transmission;friction coefficient;flash temperature;elastohydrodynamic lubrication
- 2651
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发布时间：2023-11-14 - 摘要：Abstract:In order to treat the problems of complex mathematical theory in the design of forming grinding wheel contour for complex spiral curved surface,a new numerical simulation method was proposed by integrating the coordinate system of workpiece and grinding wheel by coordinate transformation,and discretizing the surface model of workpiece and grinding wheel,then figuring out the discrete points’three-dimensional coordinates of space contact tracing line by numerical iterative algorithm,furtherly finding out the grinding wheel contour by coordinate transformation.This method has simple mathematical theory and is easy to program.Comparing with the result of analysis method,the data precision meets the requirements of product design.关键词：spiral curved surfaces;grinding wheel contour;coordinate transformation;numerical simulation;MATLAB
- 2365
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发布时间：2023-11-14 - 摘要：Abstract:The automatic transmission principle was introduced to improve the efficiency of transmission system of construction vehicles, by using experimental data of automatic speed control to establish and verify the shift model based on multi-scale wavelet neural network. The results showed that the shift model based on multi-scale wavelet neural network can achieve higher accuracy than genetic BP neural network. It can further improve the efficiency of transmission system of construction vehicles and save energy.关键词：construction vehicles;shift principle;multi-scale wavelet neural network
- 2883
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发布时间：2023-11-14 - 摘要：Abstract:A new kind of jetting valve driven by the piezo-stack using its quick response and good output properties was presented.The jetting valve was comprised of piezo-stack,flexible lever beam,needle and nozzle.The force of adhesive when jetting was analyzed.Using ANSYS software the adhesive field at the nozzle was analyzed and simulated,getting the jetting regularity affected by the needle displacement,the driving air pressure and adhesive viscosity.Then the property of the jetting valve was tested in experiment,which verified the theoretical analysis and the simulation in ANSYS software.When the adhesive viscosity is 2 Pa·s,droplets of minimum diameter 0.5 mm could be obtained from the jetting valve and conformity error is about 6%.The jetting valve provides more efficient and precise method for the electronic packaging.关键词：piezoelectric driven;flow field analysis;micro-displacement amplified;jet dispensing
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发布时间：2023-11-14
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