最新刊期
卷 47 ， 期 5 ， 2015
- 摘要：Abstract:In order to study mechanical characteristics of the oil sand core of Fengcheng oilfield in Xinjiang Karamay，a consolidated drained triaxial compression tests at room temperature were conducted on MTS 815，and the triaxial mechanics properties of oil sand under varying confining pressure were studied.Results indicated that the typical stress-strain curve of oil sand seems a hump curve，exhibiting strain-softening and shear dilatancy.Test boundary conditions and the confining pressure have significant influences on the mechanical properties of oil sand,which determine the failure modes and the post-peak softening behaviors.The deformation modulus and Poisson’s ratio of oil sand have linear relationship with confining pressure in logarithmic coordinates respectively，and the failure criterion of oil sand at low stresses can be explained approximately with the Mohr-Coulomb criterion.Based on two classical nonlinear constitutive models，by introducing new parameters，the stress-strain constitutive relationship of oil sand in Fengcheng was discussed，which demonstrated that the modified Chengdu Science and Technology University Model seems better to describe the strain-softening properties of oil sand than Nanshui Model，and able to consider shear dilatancy to some extent.关键词：oilsand;triaxialtest;strainsoftening;constitutivemodel
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发布时间：2023-11-14 - 摘要：Abstract:To increase the bearing behavior of conventional suction foundation,a modified type of the suction caisson,named as skirted suction caisson,was studied by using both the numerical method and model tests.Vertical loading-settlement curves and deformation of surrounding soil were obtained.It was shown that the skirted suction caisson can enhance the vertical bearing capacity due to adding the skirted structure.It was also found that the lid,inner and outer walls of the main bucket may provide 90% of the vertical loading,and the tip parts and inside and outside walls of the skirt account for 10%.Frictional resistance along the outer and inner walls of the main bucket increases with the increase of the ration of height to diameter.However,the resistance of tips and the outer and inner walls of the skirt accounts for less than 10% of the total resistance.Soil heave decreases with the increase of the skirt height,but increases with the increase of the e skirt width on the contrary.Contribution of skirt width to vertical bearing capacity is much greater than skirt height,but the skirt height reduces soil heave effectively.关键词：skirted suction caisson;vertical bearing capacity;soil heave;bearing proprotions;displacement vectors
- 2145
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发布时间：2023-11-14 - 摘要：Abstract:In order to study the shear capacity of basalt fiber reinforced polymer reinforced recycled concrete deep beam without web reinforcement,9 deep beams under 4 point bending test were conducted.The failure process and failure mode of the tested beam were analyzed.The relationship of shear strength among the shear span ratio,reinforcement ratio of BFRP rebar and the compressive strength of recycled concrete was also discussed,respectively.A formula based on Canadian specification and data fitting for calculating the shearing capacity of the specimens was proposed.Results showed that the main failure mode of BFRP reinforced recycled concrete deep beam without web reinforcement was the shear failure and with the increase of shear span ratio,the shear failure transforms to flexural-shear failure.The shear capacity of experimental beams decreased with the increase of the shear span ratio,while increased with the increase of the reinforcement ratio of BFRP reinforcement and compressive strength of recycled concrete.The predicted results of the adopted calculation model fitted well with the test results and had a certain degree of safety.关键词：BFRPrebar;recycledconcrete;deepbeam;shearcapacity
- 2063
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发布时间：2023-11-14 - 摘要：Abstract:In order to study the mechanical properties of the Mantou mortise-tenon joints in the post-and-lintel constructions of the ancient traditional timber buildings in the South Yangtze River Regions,the failure modes,hysteretic curves,skeleton curves,and rotation rigidities of the Mantou mortise-tenon joints under low cyclic loading were studied experimentally.Furthermore,with the consideration of the nonlinear contact influence of the mortise-tenon joint and the nonlinear stress-strain behavior of the timber material,the mechanical properties of the Mantou mortise-tenon joints were analyzed by ANSYS software.The results showed that the hysteretic curves of the Mantou mortise-tenon joints appear to be Z shape and have obvious pinch effects. During the process of the test,these mortise-tenon joints orderly pass through the elastic stage, yield stage and failure stage.The theoretical results agree well with the experimental results.The relationship among the in-plane rotational rigidity K1, out-of-plane rotational rigidity K2 and tortional rigidity K3of the Mantou mortise-tenon joint is achieved and the ratio of them is about 12∶1∶2.The results could provide the theoretical base for computing analysis and repair design of the traditional timber buildings in the South Yangtze River Regions.关键词：traditional building;post-and-lintelconstruction;mantoumortise-tenonjoint;mechanicalproperty;non-linearfiniteelementmethod
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发布时间：2023-11-14 - 摘要：Abstract:In order to study the whole process of stress and deformation of the overall structure in the earthquake,based on complex loading on multi-ribbed composite slab structure with framework at the bottom,a calculation model was established incorporated in the program IDARC by the hysteretic rules of Park-three-degradation-parameter,and the comparison and analysis was made between numerical simulation and experiment of hysteretic curves.The results showed that the curves are in good agreement,besides,it verified the correctness of the model,and provided references for the analysis and calculation of this kind of structure.Afterwards,detailed stress characteristics of the specimens in the elastic-plastic stage and crack development were simulated by ANSYS and compared with test phenomena,which showed that the design of nested structural form of multi-ribbed composite slab can improve the seismic performance of the whole structure.关键词：multi-ribbed composite slab structure with framework at the bottom;the hysteretic degradation rules of Park-three-parameter;IDARC;ANSYS;hole-wall
- 1916
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发布时间：2023-11-14 - 摘要：Abstract:In order to investigate the rational injection pressure with different orientation of natural fractures and injection-production pattern,a reservoir fracture propagation model with collinear fractures was established on the base of porous medium mechanics and fracture mechanics, and a calculation method of injection pressures was presented.Fuyu reservoir properties were applied to discuss the influence rules of reservoir fractures azimuth,injection-production well azimuth and fracture distance on water injection pressure.The results showed that under the given injection-production well azimuth,if the natural fractures are parallel to the major principal stress,the injection pressure is minimum.As the angle between natural fractures and the minor principal stress increases,the injection pressure decrease accordingly.When the natural fractures are parallel to the minor principal stress,the injection pressure is maximum,and the injection pressure increases with the injection-production well azimuth and fracture distance increases.For the sake of preventing water channeling to production well and enhancing recovery,a rational injection pressure range was proposed according to Fuyu reservoir parameters.The results were identical with practical logging data,which has a guiding significance for similar oilfield development engineering.关键词：collinearfractures;hydraulicfracturing;formationpressure;fracturedreservoir;stressintensityfactor
- 1903
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发布时间：2023-11-14 - 摘要：Abstract:To overcome the difficulty in providing upstream boundary conditions in traditional depth-averaged models for turbidity currents, a one-dimensional numerical model was proposed for predicting the coupled processes of open channel flow and turbidity current in reservoirs under a two-step calculation mode.The calculations of the open channel flow and the turbidity current alternated with each other, the relationship between the Froude number and the volumetric sediment concentration at the plunge point was used to determine the location of the upstream boundary for the turbidity current and to specify the corresponding boundary conditions,and the method for calculating the limiting height of aspiration was adopted to evaluate the outflow discharge of the current.The whole processes of two turbidity current events in the Sanmenxia Reservoir from formation to recession were simulated.The predicted plunge point locations were in agreement with the measurements,with the arrival times of the current front being satisfactorily predicted.The calculated sediment concentrations and elevations of interface between the clear-water layer and turbidity current layer agreed with the field measurements, and the simulation results indicated that the sediment delivery ratio was reduced considerably when a muddy reservoir was formed.The proposed model provided a viable tool for simulating turbidity current events and designing procedures for sediment routing.关键词：turbiditycurrent;plungepoint;two-stepcalculationmode;numericalsimulation;SanmenxiaReservoir
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发布时间：2023-11-14 - 摘要：Abstract:In order to study the high mobility behavior and erosion effect of landslide,the erosion formula was combined with thermo-poro-elastic model to construct the one-dimension long-range landslide model.The coupling numerical method based on the implicit scheme of finite volume method and TDMA algorithm was proposed to simulate the thermo-poro-elastic effect and erosion effect during the movement process of landslide.Numerical results indicated that the thermo-poro-elastic effect enhanced the landslide mobility and affected landslide erosion significantly.关键词：high-speedlandslide;thermo-poro-elasticeffect;erosion;numericalsimulation
- 2058
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发布时间：2023-11-14 - 摘要：Abstract:36 specimens were tested under three different heating conditions corresponding to three different kinds of large space fires.Effective thermal conductivities of intumescent coatings were calculated based on the test measurements.TGA tests were conducted to investigate the effect of heating rate on fire performance of intumescent coating.The study found that the maximum temperature and heating rate were different under different heating conditions of large space fire,which resulted in different expansion rate and inner structure of intumescent char.The consequence of this is the different insulating properties of intumescent coating under different heating conditions.Increasing the heating rate and the temperature resulted in better insulating properties of intumescent coating.The maximum difference of 48.8% for λminwas obtained when the coatings were exposed to different heating conditions.In addition,the variation degree of effective thermal conductivities of intumescent coating under different heating conditions was affected by coating thickness，thin coating is more sensitive to the change of heating conditions.关键词：largespacefire;insulatingproperty;intumescentcoating;effectivethermalconductivity
- 1913
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发布时间：2023-11-14 - 摘要：Abstract:Debris flows were classified into one-phase and two-phase flows according to their movement features and the size distributions of solid particles.The intermittent feature of two-phase debris flows was studied with the natural and physical model experiments.The surge character in the experiments of the two-phase debris flow was obvious, and the head of the debris flow moved intermittently.In the experiment water flow initiated sediment from bed and side slopes and transported gravel particles to the front,accumulation of the gravel in the front of the flow made the height and front slop of the debris flow increase.Suddenly,the gravel moved forward as the slop reaches the critical value.Then the head height and slope reduced to some value and the flow stag again.The sediment supplied from upstream and energy accumulation caused the debris flow moving again. Based on the two-phase debris flow experiments,the formation and development of intermittent surges process was studied and the mechanical model was established.关键词：two-phasedebrisflow;intermittentflow;energy accumulation;unsteadyflow
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发布时间：2023-11-14 - 摘要：Abstract:In order to analyze the motion characteristics of landslide failure along the arc sliding surface,based on the assumption that landslide was moving as a group of particles motion,the moving physical model of landslide was established with the consideration of the character of saturated-unsaturated soil.The landslide motion velocity and distance was calculated by using the finite difference method.A new method was presented to analyze the motion characteristics of landslide failure along the arc sliding surface. In additional,an example was given to illustration the method.The results showed that the motion velocity of landslide increases first and then decreases,meanwhile in a very short time the velocity increases to the maximum.The horizontal distance increases with the increase of the time,and the horizontal distance sharply increases in the initial sliding stage,then increases slowly till the movement stopping.The method was simple to predict the hazard scope for a rainfall-induced landslide failure along the arc surface.关键词：landslide;rainfall;sliding along circular surface;physical model of motion;kinematic factor
- 1998
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发布时间：2023-11-14 - 摘要：Abstract:To study creep properties of thenardite,triaxial compression creep tests to thenardite specimens were carried out on the RLW-2000 rock rheology testing machine.The test results indicated that the creep strain and steady creep rate of thenardite increased with the increase of axial stress under a same confining pressure,while the deformation modulus of which in loading process decreased gradually.The creep process of thenardite had a nonlinear characteristic,and the yield strength of which decreased gradually with the increase of time.On this basis,the fractional generalized Kelvin model was established by replacing the classical viscous body in the conventional generalized Kelvin model with a fractional viscous body and simplified.Then a new creep constitutive model for rock was constructed by combining the simplified fractional generalized Kelvin model with the Heard steady creep model,and the parameters of which were inversed using the creep test data of thenardite.Fitting curves and test curves conform very well to each other,which illustrated that the new creep model can well reflect the creep properties of thenardite.关键词：thenardite;creepproperties;fractionalgeneralizedKelvinmodel;Heardmodel
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发布时间：2023-11-14 - 摘要：Abstract:In order to study the creep law of marine clays,a large number of drained triaxial creep tests with undisturbed samples were carried out under different confining pressure and stepwise loading,by using the triaxial rheological apparatus.The two-dimensional finite element program CFEM 2D was developed which incorporate Adachi-Oka model with Biot's consolidation theory.The creep tests were simulated by the program CFEM 2D,and the results revealed that the model can describe the creep behavior of marine clays.The long-term settlement behavior of deep marine clays was analyzed by the program,and the results showed that the settlement rate is bigger in the initial stage of loading.In 100 years,the surface settlement attained 88.5 cm,and the excess pore water pressure nearly dissipated completely.The results error between the numerical analysis and the layer-wise summation method is about 2.5%,which verified the reliability of the finite element program.关键词：marineclays;creeptests;Adachi-Okamodel;artificialisland;numericalsimulation
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发布时间：2023-11-14 - 摘要：Abstract:Aimed at problems of unavailable and unreliable of net-flow fingerprint caused by net-flow transformation problems and network jitter,tamper proof and recoverable net-flow fingerprint coding scheme was proposed.The processed net-flow characteristic information was proposed as adaptive parameters and used as initial of hyper-chaos system.Based on that,dual fingerprint was made.The threshold theory was used to improve the tamper-proofing capability the self-recovery ability of net-flow fingerprint information.By dividing the net-flow fingerprint into two interrelated sub-fingerprint,the self-recovery ability of net-flow fingerprint was improved.What’s more,the capability of tamper proofing and self-restoration capability of tamper-proof and recoverable net-flow fingerprint coding scheme was analyzed.Finally,the availability and correctness of this scheme was verified by experiments.关键词：ne-flowexchange;net-flowcharacteristic;self-adaption;temper-proofing;self-restorationcapability
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发布时间：2023-11-14 - 摘要：Abstract:Aiming to decrease the learning error of the series of AdaBoost algorithm for multi-label classification,the AdaBoost algorithm was improved for multi-label classification by two strategies.One idea is to modify the adjustment strategy of sample distribution,and destroy the sample uniform distribution in the existing AdaBoost algorithm,in order to ensure that the increase of every weak classifier can reduce the learning error bound estimation.Another idea is to consider the effect of subsequent weak classifiers to decrease the learning error when training current weak classifier,which is different from the existing AdaBoost algorithm.Theoretically,the improved AdaBoost algorithms for multi-label classification increase every weak classifier to reduce more learning error.Theoretical analysis and experimental results showed that all the improved algorithms are effective.关键词：ensemblelearning;multi-labelclassificationproblem;realAdaBoostalgorithm;multi-classclassificationproblem;classifiercombination
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发布时间：2023-11-14 - 摘要：Abstract:Aiming at load imbalance problem in the substrate network,the substrate nodes and links with resource utilization exceed the predefined threshold value were selected for reconfiguration based on the load state of the substrate nodes and links.By using topology awareness reconfiguration model,the virtual node to be migrated was then mapped onto the nearest mapped substrate node,which is the neighbor mapping node of the migration virtual node,mapping location of these reconfiguration virtual nodes in the substrate network was optimized,therefore resource consumption of virtual network reconfiguration was reduced efficiently.Simulation results showed that the load level in the substrate is balanced efficiently,the reconfiguration path distance of virtual links are reduced greatly,and the accept ratio of virtual networks is improved by using the proposed TA-VNR algorithm.关键词：substratenetwork;virtualnetwork;reconfiguration;resourceutilization;topologyawareness
- 1995
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发布时间：2023-11-14 - 摘要：Abstract:The existing clustering approaches are lacking of researching on clustering Web services whose descriptions are semantic sparse.Therefore,a new approach was proposed to makes an attempt to solve the problem of clustering sematic sparse Web service by applying transfer learning method in the domain of Web service clustering.A dual PLSA model was introduced to integrate knowledge of target domain and auxiliary domain which can transfer knowledge using a unsupervised mode to facilitate the process of semantic sparse Web service clustering.Experimental results showed that the proposed method can improve the performance of semantic sparse Web service clustering.Compared with the approaches of K-means,Agglomerative and PLSA,the proposed approach achieves better performance of the purity and the entropy.关键词：Webserviceclustering;transferlearning;semanticsparse
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发布时间：2023-11-14 - 摘要：Abstract:In heterogeneous environment, data provenance information in ETL is represented on the basis of OPM.However,there is still a lack of consensus on conceptual representation of ETL provenance information,usage of provenance vocabulary and a consolidated access mode.A unified provenance representation mechanism,which was based on PROV,was proposed for ETL.Firstly,it presented a concept representation mechanism for ETL,which demonstrated primary provenance concepts and their relationships.Secondly,it constructed a multi-granularity vocabulary to fulfill the requirement of expressing provenance information on different abstraction levels.Finally,a standard access mode was proposed in which provenance information was organized into two levels,the bottom one was described with RDF,and the above level was formed based on query of the former.关键词：ETL;dataprovenance;interoperability;PROV;OPM
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发布时间：2023-11-14 - 摘要：Abstract:Traditional edge detection algorithms are low in noise immunity, high in edge continuity,redundant in edge details,and poor in the applicability for moving target detection.In order to treat these problems,a multiscale fused edge detection algorithm was proposed based on non-sampling Difference of Gaussian (DoG) Pyramid.With the concept of multiscale image,the algorithm combined the accurate edge information in small scale image and strong noise immunity and low edge redundancy in large scale image.Experiments verified the effectiveness of the proposed algorithm.Analysis of Abdou-Pratt quality factor on the fused edge image showed that the proposed algorithm is strong in noise immunity and accurate in edge location.Analysis of edge continuity showed that the proposed algorithm decreases edge continuity while keeps main edges,and obtains edges with higher continuity.Experiment result of vehicle detection showed that the vehicle detection result based on the proposed algorithm has higher accuracy.关键词：non-samplingDifferenceofGaussianPyramid;multiscaledecomposition;edgedetection;vehicledetection
- 2301
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发布时间：2023-11-14 - 摘要：Abstract:Inordertoextractthestablelong-termfeatureswhenthedataisinsufficient,agroup-Lassobasedmixturediscriminantanalysismethodwas proposed.Firstly,theGaussianmixturemodelwas used todescribethedistributionofdata,andtheobjectivefunctionofgroup-Lassobasedmixturediscriminantanalysiswasgotbasedonthequadraticvariationalformofthegroup-Lasso.Subsequently,throughdefiningtheblurredresponsematrix,theproblemofsolvingthediscriminantanalysistransformmatrixwasfiguredoutbyeffectivelycombinedwiththeoptimalscoringmethod.Finally,thesuper-vectorwasobtainedbyconjoinedtheadjacentframesMelfilterbankoutput,andthetime-frequencyfeaturewasextractedafterthedimensionalityofsuper-vectorreducedusingthetransformmatrix.Theexperimentalresultsshowedthat thismethodcanobtainsparsetransformationmatrix.ComparedtothePLDAandSLDAdiscriminantanalysismethod,therecognitionaccuracyrateisincreasedby0.71%and1.53%respectively,andwhenlackofdata,thismethodcanachievehigherrecognitionperformance.关键词：mixturediscriminantanalysis;group-Lasso;featuretransformation;speechrecognition
- 2033
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发布时间：2023-11-14 - 摘要：Abstract:In order to study the relationship between coil current and electromagnetic system performance,an electromagnetic system mathematical model of hydraulic and spring high-voltage circuit breaker operating mechanism was established by magnetic circuit.The effect of parameters,such as coil voltage,coil loop resistance and the core air travel,on coil current was analyzed in theory and simulation.Tests were carried out on high-voltage circuit breakers of 126 kV spring mechanism and 550 kV hydraulic mechanism with changing electromagnetic system parameters.The simulation and experimental results showed that electromagnetic system parameters,such as closing coil voltage,coil loop resistance and core air travel,have a significant impact on the performance of the operating mechanism,and would affect the operation of high voltage circuit breakers performance and reliability.The research results could have important implications for the status assessment of high voltage circuit breaker operating mechanism.关键词：high-voltagecircuitbreakers;electromagneticsystem;coilcurrent;operatingmechanismperformance
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发布时间：2023-11-14 - 摘要：Abstract:According to the systems like Buck converters which has the characteristics of strong nonlinear and stochastic load disturbance，and considering engineering demand of digital control implementation, a discrete-time terminal sliding mode control strategy was proposed based on conventional terminal sliding mode control. The stability of the system, the output tracking errors under the discrete-time terminal sliding mode controller and discrete-time linear sliding mode controller were analyzed. Finally, the proposed method was applied to the output voltage control of Buck converter and simulation was done. The steady-state error of the output, the settling time and the controller output chattering under the above two discrete-time controllers were compared. The simulation results showed that discrete-time terminal sliding mode control improved dynamic and static characteristics and robustness performance of the system effectively.关键词：digitalcontrol;discrete-timeterminalslidingmodecontrol;Buckconverter;robustness
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发布时间：2023-11-14 - 摘要：Abstract:An exact and approximation conjugate principle based on envelope theory and modified kinematic method was presented,respectively,by using the double-circular-arc common tangent tooth profile (DCTP) and considering the effect of the tooth profile and elastic deformation of harmonic drive (HD).The results showed that there exists two conjugate existent domains(CEDs) and dual conjugated phenomenon.The CED and conjugate tooth profile (CTP)calculated based on envelope theory and modified kinematic method perform the similar property.The CTP,the locus of the conjugate completion phase,and the backlash that is near the major axis of wave generator (WG) are slightly influenced while using the approximation conjugate principle.Meanwhile,the CED,the movement trails of the conjugate initial state and the backlash that far from the major axis of (WG) are evidently influenced.关键词：harmonicdrive;double-circular-arctoothprofile;conjugateprinciple;comparativeanalysis
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发布时间：2023-11-14 - 摘要：Abstract:Since the biped robots are difficult to avoid obstacles in real time due to the balance constraints when the biped robots walk in actual environments,a path planning and obstacle avoidance method was proposed based on the rotating potential field.First,the idea of footprint planning was introduced into the local real-time path planning based on the potential field.Then,the local minima problem in the traditional potential field was solved by designing a new obstacle rotation potential field and the real-time obstacle avoidance was achieved using the mapping relationship.Finally,the effectiveness of the proposed method was confirmed by obstacle avoidance experiments on a small size biped robot in the environment with U-shaped obstacles关键词：bipedrobot;rotatingpotentialfield;obstacleavoidance;pathplanning
- 1848
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- 2
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发布时间：2023-11-14 - 摘要：Abstract:To solve the problem of trajectory optimization and connection of painting robot for complex geometry on the free-form surfaces,based on the combined surface of ruled surfaces,a mathematical model of spray gun trajectory optimization was established,meanwhile a kind of algorithm procedure was designed to solve the problem of trajectory connection to spray painting robot on combined surface of ruled surfaces according to the theory of curved surface modeling and intelligent algorithm.Firstly,according to surface character,the ruled surface and the paint gun mathematical model for complex geometry on free-form patches was established.Secondly,the selected juncture between combined surfaces of ruled surface was optimization by the paint gun model.The effectiveness of above model was verified.Based on the model,a algorithm program was devised.The simulation tests verified the validity and feasibility of the trajectory optimization.The continuity spraying of combined surface of ruled surfaces was realized.关键词：combinedsurfaceofruledsurfaces;trajectoryoptimization;trajectoryconnection;spray-painting robot
- 1819
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发布时间：2023-11-14 - 摘要：Abstract:The turbulent diffusion and thermophoresis of particle in the process of gas-liquid cross flow used to absorb PM 2.5 were investigated by experiment and simulation.The stochastic trajectory model was proposed to investigate the motion situation under thermophoresis of particle and the simulation results were compared with two detection methods of chemical analysis and gravimetric analysis.The results showed that the trap rate of particle by chemical analysis was basically the same as it by gravimetric analysis,and the consistency of two detections of particle concentration was verified.When the gas velocity rate was 1 m·s-1 and the turbulent diffusion model was also considered into numerical computation,the relative deviation between numerical simulation and experiment was reduced from -60% to ±30%. which proved that the turbulent diffusion was one of the most important factors affecting the particle removal in the system.关键词：gas-liquidcrossflow;detectionsofparticleconcentration;diffusion;stochastictrajectorymodel
- 1970
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- 5
发布时间：2023-11-14 - 摘要：Abstract:The heat transfer performance of metal hydride reactors is poor.To solve this problem,Taguchi methods was used to optimize the design parameters of metal hydride reactors equipped with helical coil heat exchanger.A three-dimensional multi-physics model for the metal hydride reactor was proposed and solved using the commercial software package COMSOL Multiphysics V4.4.Some typical combinations of structural parameters for helical coil tubes were selected by using Taguchi methods,and the performance of the reactors with different helical coil tubes was evaluated by numerical simulations based on the reactor model.The analysis results indicated that the performance of the metal hydride reactor equipped with the helical coil heat exchanger was better because the heat transfer coefficient and the heat transfer area of the helical coil heat exchanger were larger in compared with the straight tube.As the pitch number of the helical coil (N) and the minor radius of the helical coil (do) increased,the gravimetric heat storage rate (GHSR) increased.However,the major radius of the helical coil (D) had a little effect on the reactor performance.The optimal parameters of the reactor were D of 32 mm,N of 6 and do of 8 mm, and accordingly the maximum value of GHSR was 62.90 W/kg关键词：metalhydride;reactor;helicalcoilheatexchanger;Taguchimethods;heatstorage
- 1631
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发布时间：2023-11-14 - 摘要：Abstract:Esterified starch samples with low,moderate and high levels of substitution degrees (DS) were prepared in dry-state with acetic anhydride by using NaOH as catalyst.FTIR and XRD were applied to detect the changes of starch structure after the modification.The results showed that the associated hydroxyl groups in starch declined sharply,but the carbonyl group and ester group grew gradually with the increase of DS. The crystallinity in starch granule was decreased along with the modification. Changes of carboxyl group content during the modification demonstrated that the esterification of starch fitted the characteristic of second-order reaction kinetics.The reaction activation energy was 36.16 kJ/mol.关键词：acetic anhydride;corn starch;dry method;esterification
- 1900
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- 4
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发布时间：2023-11-14 - 摘要：Abstract:The heat-shock method was used to treat immobilized activated sludge, and NO2--N accumulation was successfully achieved. The investigation of the temperature and processing time of the heat shock revealed that nitrite oxidizing bacteria (Nitrite oxidizing bacteria, NOB) was completely deactivated when heated at 60 ℃for 10 min, while ammonia oxidizing bacteria (Ammonia oxidizing bacteria, AOB) still exhibited some activity. PCR-DGGE revealed that NOB residue after heat shock were Candidatus Nitrospira defluvii, which only when the biomass reach a certain value to appear nitrification performance. Two different temperatures were used to heat shock the immobilized granules, after which continuous-flow experiments were conducted. It was discovered that all two groups of heat shocked immobilized granules could remain stably nitritation, but the higher the temperature the longer the time was required for start stable nitritation. However,NO3--N accumulation occurred in the reactor after stably nitritation for 65 d. Therefore, the immobilized granules were heat-shocked again, and nitrite nitrogen accumulation recurred in the reactor.关键词：nitritation;heat shock;immobilized granules;activated sludge
- 1645
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发布时间：2023-11-14 - 摘要：Abstract:The semiconductor properties of the rebar passive film formed in the simulated pore solutions for different dosages of sodium hydroxide (NaOH) activated slag were investigated with free corrosion potential, Mott Schottky plots. The detrimental effect of different chloride ion concentrations on the passive film and the threshold chloride ion concentration were also studied. The rebar passive film formed in the simulated pore solutions of Ordinary Portland Cement (OCP) was tested for comparative purpose.The results indicated that the passive film formed in the simulated pore solutions of NaOH activated slag needs 18 d~26 d. When the dosage of NaOH is low (2% or 4%),the passive film has the characteristics of bipolar semiconductor structure (n-p).As the dosage of sodium hydroxide increases by 6%,8% and 10%,the passive film is changed to tripolar semiconductor structure (p-n-p).So the corrosion resistance of passive films is improved with the increasing dosage of NaOH.When the sodium hydroxide dosage is higher than 6%, the steel resistance to chlorine ion corrosion ability is better than the contrast group from Portland cement.The threshold chloride ion concentration is 0.11 mol/L when the dosage of sodium hydroxide is 10%, while the control sample formed from Portland cement is only 0.03 mol/L.关键词：rebarpassivefilm;freecorrosionpotential;semiconductorproperty;Mott-Schottkyplot
- 2192
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发布时间：2023-11-14
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