最新刊期
卷 42 ， 期 3 ， 2010
- 摘要：Abstract:Collapse is the dominant geological disaster in rocky mountain area, and usually many individual-perilous rock or bulk-perilous rocks exist in the source of collapse. The formation mechanism of perilous rock is one key link for hazard mitigation of collapse. According to the field investigation, four types of perilous rock at the source of Mt. Hongyan in the national scenic spots of Simianshan are classified as the falling perilous rock, the toppling perilous rock, the sliding perilous rock and the counterfort perilous rock, with the percentage of 70%, 15%, 8% and 7%, respectively. The general geological conditions to trigger the collapse disasters in the Mt. Hongyan are concluded aslandforms with four cliffs, rock composite with sandstone and mudstone alternatively, and three sets of rockmass structure planes with the orthography. Field observations have identified the pacemaker of rock cells in mudstone below cliff, the weathering velocity of mudstone in rockcell under pressure is about 5.2 cm/a, 2~6 times exposing in air. Further, based on the geomorphology the chained principle for the developing of collapse in Mt. Hongyan is revealed. The result shows that collapses are easy to take place when the length of rock cell is over 3 m.关键词：collapse disaster;base rupture under pressure;chained principle;sourse of collapse;perilous rock;Mt. Hongyan
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发布时间：2023-11-14 - 摘要：Abstract:Freeze-thaw action caused by seawater in the North Sea region of China has an important influence on the safety and stability of concrete bay bridge.The decay laws of mechanical properties were obtained through a great deal of concrete freeze-thaw cycle laboratory tests,such as ultimate compressive strength，peak strain,ultimate tensile strength and elastic modulus of concrete structure of pier of Tsingtao bay-bridge.And the freeze-thaw damage constitutive equation of concrete was deduced.According to the relativities of tests between laboratory and field,the degradation laws of mechanical properties and damage constitutive equation of concrete of the pier in different time were established. The finite element model was established for basic structures of the Bay Bridge pier of Cang-Kou Sea-route Bridge in Tsingtao. Through the numerical analysis of the finite element model based on nonlinear theory the location and variation trends about maximum stress and maximum vertical displacement of the basic structures of the pier in different times were obtained. The results could provide references for structure design and maintenance of Tsingtao concrete bridge.关键词：Tsingtao bay-bridge;concrete;freeze-thaw action;tests;damage constitutive equation;numerical analysis
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发布时间：2023-11-14 - 摘要：Abstract:The fluctuating pressure for three plug dissipaters，named as linear plug, stepped plug and gradually contracted plug, were measured and analyzed. From the perspective of fluctuating pressure, the characteristics of anti-cavitation for gradually contracted plugs which were arranged in discharge tunnel were investigated. The results showed that the maximum RMS（root-mean-square） of wall fluctuation pressure appears at 0.1 ~ 0.3 times tunnel diameter away from inlet of the plug, decreases rapidly along the plug wall and then becomes stability after 4 times tunnel diameter. The RMS of wall fluctuation pressure of the contracted plug is smaller than that of other two plugs when the outlet diameter and the flow velocity are certain. The fluctuating pressure distribution is approximately the Gauss distribution. For gradually contracted plug, it is conservative to calculate the minimum pressure using 6 times the RMS of fluctuation pressure. Pressure distribution were measured and analyzed for a plug discharge tunnel on 1∶40 orthodox model. The results showed that the minimum pressure in the tunnel is 3.4×9.8 kPa, so the probability of cavitation occurrence is small.关键词：plug dissipater;fluctuating pressure;cavitation
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发布时间：2023-11-14 - 摘要：Abstract:The mathematical models were established for parallel pumps, outlet valves and pneumatic tank in a make-up water system to study hydraulic transients after electricity failure. The calculated results showed that the negative pressure and the water column separation in local salience could be avoided when the pneumatic tank was mounted near pumps for the raising of minimal water hammer pressure on long pipeline. The total volume and initial capacity of pneumatic bag were determined by calculations. Since the backflows generated in pumps ahead of time obviously the closing laws of outlet valves were needed to adjust correspondingly.关键词：make-up water system;pneumatic tank;water hammer
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发布时间：2023-11-14 - 摘要：Abstract:Aiming at the defects of FEM method such as iso-parametrical mesh, the triangular (tetrahedral) mesh and the meshless, the theory of TFEM was introduced. Around the concept of applying the advantage ideas of meshless methods to FEM and reproducing the interpolation of FEM, it was applied to geo-engineering projects. Some engineering examples showed that this method possesses high accuracy and continuous stress on triangular (tetrahedral) mesh.
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发布时间：2023-11-14 - 摘要：Abstract:The vortex settling chamber is an efficient and economical type of sediment extracting device. To obtain comprehensive information about the flow characteristics in vortex settling chamber, and to explore its working mechanism, the large eddy simulation model and VOF (volume of fluid) method were applied to simulate water-air two-phase flow in vortex settling chamber. The calculated results of average velocity were in good agreement with experimental data measured by Laser Doppler Velocimeter (LDV). The simulation results gave some new understanding on the three-dimensional velocity distribution. Based on the calculation secondary flow was found clearly and it was critical for transporting and removing sediment efficiently in vortex settling chambers.关键词：vortex settling chamber;large eddy simulation;secondary flow;VOF method
- 3210
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- 9
发布时间：2023-11-14 - 摘要：Abstract:Two-dimensional mathematical model of water and sediment was adopted to study the infection of erosion on the downstream river in Dadu River after a hydropower station had been built. Some parameters, such as water level, velocity, and erosion depth of river-bed were analyzed in the condition of usual flood.The result showed that rinsing discharge can lead to the adjustment in the downstream river cross-section morphology, the cutting in the overall of the riverbed, the uniform velocity distribution and the significantly decreasing of water level.关键词：clear water scour;numerical model;adjustment of river-bed;velocity distribution;water level
- 3167
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发布时间：2023-11-14 - 摘要：Abstract:The deformation characteristic of surrounding rock in the underground powerhouse of a hydropower station is analyzed by R/S method and fractal theory. Hurst indexes and fractal dimensions of displacement time series of all monitoring points are calculated. Fractal dimension criterion is presented. Hurst indexes of displacement-time series of all measurement points are greater than 0.5 and less than 1, and Hurst indexes of displacement-time series in cross-section neighboring from M410 approximate 1, which shows that the deformation of surrounding rock will continue to grow up and its increasing rate keeps accelerating. From one cross section to another, fractal dimension of displacement time series collected by multipoint extensometer in two shallower measurement points(orifice、5.0 m) increase and then decrease, and fractal dimension in fractured cross-section where M410 is installed is least, which indicates that the occurrence of dimension minimum is a alarm for the forthcoming cracking of surrounding rock. However, dimension in two deeper measurement-points(11.0 m，17.5 m) do not have the characteristics similar to the one in two shallower measurement points. It is showed that crack depth in the cross-section where M410 is installed should be greater 5.0 m and less than 11.0 m.关键词：deformation of surrounding rock;displacement-time series;fractal dimension;R/S method
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发布时间：2023-11-14 - 摘要：Abstract:The dynamic control bound of flood limited water level (FLWL) is a fundamental and key element for implementing reservoir FLWL dynamic control. The acceptable risk constraints and quantificational analysis of flood control operation were proposed by considering the most important risk sources, i.e., reservoir inflow forecasting error and uncertainty of flood hydrograph shape. The inflow uncertainty, risk analysis and the process of dynamic control bound determination were incorporated organically, and a dynamic control bound of reservoir FLWL was calculated using forecasting pre-release and Monte-Carlo simulation methods. The application results of the Three Gorges Reservoir (TGR) showed that the dynamic control of FLWL can effectively increase middle and small flood water resources utilization rate without increasing flood control risk. The TGR could generate 6.99×108～14.45×108 kW·h extra hydropower energy during flood season by using 1～3 day inflow forecasting information. The proposed methods can also be applied to other reservoirs.关键词：flood limited water level;dynamic control bound;inflow uncertainty;risk analysis;Three Gorges Reservoir
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发布时间：2023-11-14 - 摘要：Abstract:A large number of column-beam joints(C-BJ) have been damaged in the Wenchun earthquake. Thereby a proper method is urgently needed for strengthening the damaged joints. This paper presented the experimental study on the seismic behaviors of 4 repaired C-BJs, 2 of which had been pre-damaged under cyclic loads. The test procedure included pre-damage, rehabilitation and re test under cyclic loads. The test results showed that the failure mode of strong beam and weak column changed into strong column and weak beam after rehabilitations. The analysis of the hysteresis curves, ductility, and skeleton curves showed that the method of enveloped steel has significant improvements in both the stiffness and all aspects of seismic performance. The study indicated that the repaired C-BJs can reach or even exceed the level of their original seismic performance before pre-damage.关键词：earthquake;damage;3D frame joint;repair;enveloped steel;earthquake resistance
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发布时间：2023-11-14 - 摘要：Abstract:Slope stability analysis is a complex system engineering problem. Based on the principles of Bayes discriminating analysis(BDA) theory and the actual characteristics of the project, the Bayes discriminating analysis model to predict slope stability was established to predict slope stability. Six indexes, i.e., unit weight, cohesion force, internal friction angle, slope angle, slope height, and pore pressure ratio were used as discriminant factors to establish a discriminant analysis model for slope stability forecast. Bayes discriminant functions obtained through training 32 measured data of slope were employed to compute the Bayes function values of the evaluating samples. The cross-validation method was introduced to verify the stability of BDA model and the ratio of mistake-discrimination was low after the BDA model was trained. Seven data in the slope engineering were used to test the discriminant ability of BDA model, the maximal function value was used to judge which population the evaluating sample belongs to. The results showed that the prediction results are identical with actual situation, and consistent with the support vector machine model, which prove that the BDA model has good classifying performance, high prediction accuracy and low misdiscrimination rate and can be used in practical engineering.关键词：slope stability;prediction;Bayes Discriminant Analysis(BDA);cross-validation method
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发布时间：2023-11-14 - 摘要：Abstract:In order to investigate the yielding mechanism, spread of plastic area and collapse mechanism of tri-directional beam string structures(TBSS), the elastoplastic ultimate capacity of the TBSS of a real project was analyzed with the finite element method. The effects of connection condition of arch root, cross-sectional moment of inertia of arches, areas of cable and pretensioned force of cable on the ultimate capacity were also studied. The results showed that this TBSS has good performance of inner force redistribution and the collapse of the whole structure is due to material damage. The ultimate capacity has small relation with the connection condition of arch root, but the pin-ended should be used for the arch roof from the collapse mechanisms of the whole structure. And the ultimate capacity can be enhanced by increasing the cross-sectional moment of inertia of arches. In order to prevent first failure of the cable, the proper cable area and pretesioned force should be chosen.关键词：beam string structure;elastoplasticity;nonlinear analysis;mechanism;cable
- 2711
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发布时间：2023-11-14 - 摘要：Abstract:A three-dimensional finite element model was developed to calculate the rain-fog convection and sedimentation in valley during the flood discharge. By the proper solution of the concentration gradient vector, the nonnegative type and monotonic changes of the concentration is maintained during the transportation. With the concept of raindrop size distribution and settlement velocity, the formulas was derived for the quantitative conversion between the rainfall intensity and water concentration, which is available to couple the boundary with other inner field numerical models. The distribution of rainfall intensity from the cavity discharge was simulated under the different wind fields in Pubugou hydropower station, the calculated results accord with the real physical mechanism well.关键词：flood discharge atomization;rain-fog transportation;finite element model;rainfall distribution;water concentration
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发布时间：2023-11-14 - 摘要：Abstract:In order to obtain structural dynamic response,a new step-by-step integration method was presented. Thismethod was introduced by quadratic Lagrangian interpolation of the nodal displacements within local time domain. Single parameters θ was varied to obtain good stability and accuracy. This method is characterized with good stability, quadric precision, self-starting and simple numerical format. Compared with the methods of Newmark,Wilson, and precise integration at different θ, this method is more accurate and reliable.关键词：dynamic response;step by step integration method;quadratic Lagrangian interpolation;stability
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发布时间：2023-11-14 - 摘要：Abstract:Aiming at the deficiency of hydrological information in the estimation of parameters in hydrological models, based on the combination of Green-Ampt infiltration model and isotopic mixing model, parameters were estimated in Green-Ampt infiltration using isotopic information through rainfall infiltration experiment. Experimental results showed that the estimation values of parameters in Green-Ampt infiltration model using isotopic information were close to measured values; parameters obtained by using isotopic and hydrological information were better than those only using hydrological information.关键词：hydrogen and oxygen stable isotopes;Green-Ampt infiltration model;isotopic mixing model;parameter estimation
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发布时间：2023-11-14 - 摘要：Abstract:To establish a new design method of anchorage cable that is more dependable or reliable than the commonly used uniform design method and the integral principle based non uniform design method, the theoretical P-S relationship of anchorage cable, which is accordant with some P-S curves gained from on site pullout test, was deduced and investigated, basing on load transfer principle and constitutive model of interface between mortar and surrounding rock or soil. An on site pullout test based design method, as a dynamic feedback design method, was proposed. The design parameters in this method, such as contact rigidity and elastic shear displacement of interface between mortar and surrounding rock or soil, were calculated from P-S curve obtained from on-site pullout test that can synthetically embody complex engineering conditions, and quantitative design permitting plastic yielding of interface is viable. To demonstrate the realization approach of the new design method, a calculation example was given. The result showed that the new design method is more sound or rational than the conservative and traditional uniform design method,although its practical application in engineering may need further tests in the future.关键词：anchorage cable;dynamic feedback design method;load transfer principle;on-site pullout test;P-S curve
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发布时间：2023-11-14 - 摘要：Abstract:In order to solve the problem that the calculation formulas of critical depth in arched-section tunnel aren′t expressed by explicit function, a new direct method for calculating critical depth of a arched-section tunnel, which follows from an analysis of the value calculation on the relationship between the relative critical depth and the introduced dimensionless parameter, was derived from transforming the critical flow equation based on improved particle swarm optimization. Error analysis and a computed illustration using the direct formula indicated that the maximum relative error is 0.37 percent in the utility range (ratio of critical depth to arch radius in 1.00～1.85), and the formula has definite conception and brief form.关键词：hydraulic calculation;critical depth;direct method;arched-section
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发布时间：2023-11-14 - 摘要：Abstract:In order to solve the problem that the traditional relation function between capillary pressure and saturation for the description of porous media flow is not unique， based on macroscopic continuum medium theory and the general balance laws for mass, momentum and volume，and introducing the residual saturation as state variable，a new constitutive relations model of capillary pressure-residual saturation-relative permeability for two-phase immiscible and incompressible fluids flow was formulated. Compared with the traditional approach，the developed model is more general and requires fewer parameters，moreover，the capillary pressure and relative permeability functions are expressed as a closed explicit formula. The experiment results indicated that the model simulates the process of two-phase immiscible displacement well，and also could be applied to explain process dependence and hysteresis phenomenon in capillary pressure and to predict spatiotemporal distributions of residual saturation.
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发布时间：2023-11-14 - 摘要：Abstract:To examine the impacts of the Manwan reservoir sediment trapping on the physical and chemical characteristics of the sediment downstream, laser grain size, XRD and XRF were employed to test the grain sizes, mineralogy and element compositions of suspended sediments and bed loads sampled from the mainstream and many tributaries in the middle and lower parts of the Lancang River. Results indicated that: the grain sizes frequency curves are mostly showed as unimodal and charactered by wide range of grain size distributions; the suspended sediments are well sorted; the bed loads appear bimodal distribution and narrow range of grain sizes, and poorly sorted; suspended sediments and bed loads are primarily composed of quartz which account for 60% to 80%; element compositions of suspended sediments are not different very much between upstream and downstream,but those of bed loads present a decreasing trend from upstream to downstream; sedimentation in the Manwan Reservoir has evident effects on the grain size and mineralogy of sediment, also causes some changes in the element composition, which is showed as normal elements but silicon take little changes, and some heavy metal are trapped in the reservoir.关键词：sediment characteristics;reservoir sedimentation;grain sizes analysis;mineralogy composition;Lancang River
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发布时间：2023-11-14 - 摘要：Abstract:A novel adsorbent, Zr(IV)-loaded collagen fiber (ZLCF), was prepared and its adsorption characteristics to benzoic acid (BA), o-phthalic acid (o-PA), p-phthalic acid (p-PA) and m-phthalic acid (m-PA) from aqueous solution were investigated. It was found that the adsorption equilibrium data of these benzene carboxylic acids can be well fitted by both Langmuir and Freundlich models. But the adsorption capacity of the benzene carboxylic acids changes with the number and position of carboxyl groups on benzene ring. In general, ZLCF has high adsorption capacity to all benzene carboxylic acids investigated. The adsorption capacity of BA, o-PA, m-PA and p-PA was 0.4616, 0.5892, 0.4912 and 0.3138 mmol/g, respectively, when 10 ml of 6 mmol/L benzene carboxylic acid solution was adsorbed by 0.05 g ZLCF at 293 K. Furthermore, the studies of the adsorption kinetics indicated that the adsorption kinetics of BA was close to the pseudo first-order-rate model and thus the boundary diffusion would be the rate-controlling step. In contrast, the adsorption kinetics of o-PA, m-PA and p-PA can be well described by the pseudo-second-order rate model, which implies that the chemical adsorption should be the rate-controlling step.
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发布时间：2023-11-14 - 摘要：Abstract:In order to investigate the effects of electrode factors on electricity production and wastewater treatment in microbial fuel cell, a new anaerobic fluidized bed microbial fuel cell (AFB-MFC) was designed. The effects of various cathodes made from different materials, areas of cathode and anode, the distance between the bottom of cathode and the bottom of cathode chamber on the performance of electricity production and wastewater treatment in AFB-MFC were studied. All experiments were operated at the conditions with the aeration rate of 16~24 L/h in cathode chamber, the recirculation flow of 10.7 L/h,the influent flow of 0.6 L/h,the external resistance of 250 Ω and the COD concentration of 3000.98~3789.44 mg/L in influent. It was found that carbon paper was the best one for cathode among carbon paper, copper, aluminum, galvanized iron and iron, all having a size of 15.0 cm×3.5 cm. The optimum distance between the bottom of cathode and the bottom of cathode chamber was 17.3~20.3 cm. The optimal anode area was 160.0 cm2 when carbon papers with an area of 308.8, 232.0, 160.0 and 76.8 cm2 were used for anode. The best cathode area was 210.0 cm2 when carbon papers with an area of 241.5, 210.0, 175.0 and 105.0 cm2 were served as cathode. About 80.00% of COD could be efficiently removed under the optimal operation conditions for AFB-MFC system. The AFB-MFC system which was scaled up is conducive to the practical engineering application in the future.关键词：microbial fuel cell;anaerobic fluidized bed;electricity production;wastewater treatment;cathode;anode
- 3024
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发布时间：2023-11-14 - 摘要：Abstract:Two in-situ compound from ferron sulphate and tetra hydroxymethyl phosphonium sulphate (THPS) was synthesized according to different mole ratio between the two materials. By testing the UV absorption and FT-IR spectrum of Fe-THPS compounds, the most possible mole ratio of n(Fe(Ⅱ))∶n(THPS) was 1∶3. Then the stable constant of Fe-THPS was determined by potentiometer titration. It was found that the compound is unstable, and the stability at 30 ℃ is better than that of 40 ℃. At last, sheep skin was tanned with solo FeSO4, solo THPS, FeSO4 and THPS, Fe-THPS compound. The results showed that the hydrothermal stability of leather treated with combination tannage is higher than that of leather treated with solo tanning agents, and its shrinkage temperature can reach to 90 ℃. Fe-THPS has the best cross linking property and the leather treated with the compound has a good dry thermal stability. The tensile strength and tearing strength of leather tanned with Fe-THPS compound is enhanced obviously, which can meet the request of garment light leather.关键词：ferrous sulfate;tetra hydroxymethyl phosphonium sulphate;complexes;collagen;hydrothermal stability;modify
- 2804
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发布时间：2023-11-14 - 摘要：Abstract:Based on the analysis of milling characteristic, reasonable geometric parameters of milling cutler and coated carbide grade were selected. Reasonable geometric parameters of insert were also selected through contrast experiment of tool wear resistance and tool life, and typical wear and failure form of coated carbide tools during the milling process were presented. It was shown that TiAlN-TiN coated carbide is the proper tool material for the milling process of powder metallurgy superalloy, and the cutting tool life has reached to 20~108 min within the cutting speed region of 30~70 m/min. Because of the high milling temperature and severe mechanical shock, main wear and failure form of experimental inserts can be described as chipping and peeling off in the rake face, the primary mechanisms are abrasive, adhesion, diffusion and fatigue failure.关键词：powder metallurgy superalloy;coated carbide tool;cutting performance;wear mechanism;failure
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发布时间：2023-11-14 - 摘要：Abstract:Combined with FEA software, X-ray diffraction (XRD) and layer removal method, a comprehensive method of simulation-experiment was proposed for residual stress measurement in quenched aluminum alloy thick plates. Analysis of the results proved that the comprehensive method could compensate the shortcoming of a single method, and satisfy the validation and examination among methods on the stress-field of thick plate. It could be used to establish an effective FEM of residual stress in quenched plate, in which stress field of the whole plate can be obtained.And this method is also able to accurately predict the stress in plate, since the stress resulted by FEM match with experimental results and the average deviation of quenching stress is less than 10%.关键词：residual stress;stress prediction;aluminum alloy;simulation
- 3250
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发布时间：2023-11-14 - 摘要：Abstract:Based on the CT data of a patient’s femur, a three-dimensional FEA medical model of femur treated with AHJC was rebuilt, under the load conditions of 1.5 and 2.5 times standard body weight (70 kg), and the biomechanics of the model were analyzed for three different healing periods by FEA. The results showed that in the initial period post-operation, the Young’s modulus of tissue in host-donor junction area was low, and there were serious stress concentrations in the middle of junction area and the bone cement, meanwhile, the maximum stress in bone cement was higher than the compress strength of it, so it would be in the risk of crash. With the growth of new bone in host-donor junction area, the Young’ modulus of the tissue increased, and the stresses shielding and concentration in the junction area and bone cement decreased greatly. The stress distribution in host-donor junction area will be in the level of normal bone, after the wound healed and the tissue in host-donor junction area gradually grew to be mature bone. Porous hydroxyapatite (HA) ceramics used as bone-scaffold in the host-donor junction area would decrease the stress shield and concentration in the junction area, and improve the biomechanical safety properties for clinic application of the AHJC.关键词：biomechanics;allograft hip joint composite;host-donor junction area;finite element analysis
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发布时间：2023-11-14 - 摘要：Abstract:An exposure experiment of concrete was carried out in marine atmospheric environment,the total chloride ion and free chloride ion contents of concrete were determined.The characteristics of free chloride ion and bound chloride ion contents changing along with time were investigated in the process of chloride ion diffusion.Meanwhile,chloride ion binding capacity was calculated at each different exposure time and diffusion depth, and the effect of exposure time and diffusion depth on chloride ion binding capacity of concrete were discussed by regression analysis.The results showed that the chloride ion binding capacity is the power function of exposure time and meets cubic polynomial function with diffusion depth.The fitted values agree well with the measured values and it indicate that the functions are efficient.关键词：concrete;chloride ion;binding capacity;exposure time;diffusion depth
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发布时间：2023-11-14 - 摘要：Abstract:In order to solve the problems caused by the traditional ant colony algorithm, such as searching slowly, cling to prematurity, standstill, and the inefficient and useless redundant iteration caused by feedback underutilized in traditional immune algorithm，an algorithm combined ant colony algorithm and Immune Clone hybrid algorithm was proposed. With this algorithm, initial information distribution of ant colony algorithm was generated by immune algorithm in the early work, and the information on the path was adjusted by path concentration of inhibition mechanism at latter work, which kept diversity of ant colony. The algorithm was used to solve the traveling salesman problem for computer simulation.The experimental results showed that the algorithm has targeted improvements, good convergence speed and optimization capabilities.关键词：artificial immunity;ant colony algorithm;TSP
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发布时间：2023-11-14 - 摘要：Abstract:To address the traditional Traveling Salesman Problems (TSP) with the combinatorial explosion property, a novel MHC-inspired antibody clone optimization algorithm (COAMHC) was proposed by drawing inspiration from the features of Major Histocompatibility Complex (MHC) in the biological immune system. COAMHC preserves elitist antibody genes through the MHC string to improve its local search capability and improves the diversity of antibody population by gene mutation and some new random immigrant antibodies to enhance its global search capability. The experiments of comparing COAMHC with the canonical clone selection algorithm (CLONALG) were carried out for the TSP and results indicated that the performance of COAMHC is better than that of CLONALG. The COAMHC algorithm provides new opportunities for solving previously intractable optimization problems such as TSP.关键词：artificial immune system;TSP;MHC;antibody clone algorithm;optimization
- 3094
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发布时间：2023-11-14 - 摘要：Abstract:In order to improve the efficiency of image segmentation, Quantum-behaved Particle Swarm Optimization (QPSO ) algorithm was used to image threshold segmentation, and BQPSO, an improved threshold searching algorithm based on QPSO, was proposed. BQPSO algorithm introduced a boundary-controlled strategy to reset particles back to a random point around the border in search region when particles were massed on border, so to prevent them from aggregating at the border. By Boundary-controlled strategy, a diversity of the swarm was maintained , local optimal solution was avoided efficiently, and the global search ability was enhanced. The experiment result showed that, compared with GA,PSO and QPSO, BQPSO algorithm possess obviously advantage in threshold searching efficiency, searching accuracy and image segmentation effect.关键词：QPSO;GA;PSO;Otsu;Boundary-controlled strategy;Dual-threshold image segmentation
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发布时间：2023-11-14 - 摘要：Abstract:In order to overcome the shortcomings of traditional noise removal methods which the remaining noise is still large, an algorithm which was based on the local feature of the image was introduced for removing the Gaussian noise according to the impact of Gaussian noise on visual images. Firstly, the pixel was or wasn’t lie smoothing domain was estimated based on the local pixels’ continuity in the image. Secondly, the edge and texture of the image were extract by morphologic according to the local continuity properties of texture and edge, then the pixel contaminated with Gaussian noises was estimated. Lastly, the noise point in the smoothing domain was removed making use of the adaptive neighborhood, local smoothing for the edge or texture pixel. Comparing to the traditional method, this algorithm could preferably remove the noise and improved image visual effect.关键词：Gaussian noise;local feature;morphologic;noise removal
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发布时间：2023-11-14 - 摘要：Abstract:To effectively reduce color artifacts and blurring of the CFA interpolation images, a support vector machines (SVM) based interpolation scheme is proposed, in which support vector regression (SVR) is used to estimate the color difference between the two color channels with applying spectral correlation of the R, G, B channels. The neighbor training sample models are selected on the color difference plane with considering spatial correlation, and the unknown color difference between two color channels is estimated by the trained SVM and input pattern, then the missing color values at each pixel can be obtained. Simulation results indicate that the proposed scheme produces visually pleasing full-color images and obtains higher PSNR and smaller NCD results than other conventional CFA interpolation algorithms.关键词：image interpolation;color filter array;Support Vector Machine(SVM);Support Vector Regression(SVR)
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发布时间：2023-11-14 - 摘要：Abstract:Aiming at the energy hole problem in wireless sensor networks, a model considering energy of sensing, processing, transmitting, and receiving was established to analyze the energy hole problem. The concept of energy consuming rate was proposed, and the qualification for avoiding energy hole problem was provided. Using this model the effectiveness of some existing approaches towards mitigating the energy hole problem was investigated, such as node density, source bit rate, data fusion and routing style. The simulation results were given and compared with theoretical analysis to validate the correctness of this model, and the best way to mitigate the energy hole problem was suggested.关键词：wireless sensor network;energy hole;model;data fusion
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发布时间：2023-11-14 - 摘要：Abstract:At present, the security of the identity based proactive threshold signature schemes was almost proved in the random oracle model, and the threshold values of these schemes were almost changeless. Aiming at this two problems, a proactive threshold signature scheme was presented by using the hardness of the computational Diffie-Hellman problem with no trusty center and changeable threshold value, based on the modification of Paterson’proposed identity based signature scheme. The scheme’s correctness was exactly proved in terms of bilinear pairing technique and its security was analyzed and proved in detail in the assumption of the computational Diffie-Hellman problem.关键词：standard model;proactive threshold signature;computational Diffie-Hellman problem
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发布时间：2023-11-14 - 摘要：Abstract:In order to improve TCP throughput over wireless ad hoc networks,the relation between TCP data flow packet losses caused by network congestion and queue length、TCP sending windows over wireless ad hoc networks is simulated and analyzed. The TCP sending windows up bound is derived using network calculus theory based on already exist wireless link throughput model. When the value of sending windows is less than WThresh,TCP-WThresh accurately judges packet losses as non-congestion losses and avoids mal-operation of congestion control. Thus, the improved TCP based on WThresh performs well over special wireless multihop ad hoc networks scenarios.关键词：wireless ad hoc network;deterministic network calculus;TCP flow;packet loss;congestion windows up bound
- 2693
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- 0
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- 0
发布时间：2023-11-14 - 摘要：Abstract:In order to alleviate the chattering phenomenon suffered in traditional sliding-mode control with exponentially reaching law(TSMC), an intelligent sliding-mode controller is proposed based on cloud models reaching law. The combination between cloud models and reaching law is introduced for the first time. With reasoning method of cloud models, the reaching speed can be adjusted dynamically to ensure that the system states can reach the sliding surface quickly and stably. Finally the designed sliding-mode controller is used to stabilize a parallel-type double inverted pendulum system (PTIPS), and the simulation results demonstrate that this method is effective and has strong robustness to system parameter uncertainty and external disturbances.关键词：cloud models;exponentially reaching law;sliding-mode control;parallel-type inverted pendulum
- 2469
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- 4
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- 1
发布时间：2023-11-14 - 摘要：Abstract:In order to maximize the throughput of MIMO-OFDMA downlinks by using delayed channel state information, an adaptive transmission scheme combining Orthogonal Space-Time Block Code and eigen-beamforming was proposed,and subsequently a computationally efficient two-step sub-carrier allocation algorithm was presented. This scheme allocated bandwidth for every user based on their average channel state and data rate requirement. Then each sub-carrier was assigned to users according to the minimum scaled constellation distance criterion, capturing multi-user diversity gain. Finally available power was distributed among sub-carriers to ensure each user’s data rate requirement. Simulation results showed that the scheme could make use of delayed channel state information and multiple transmit antennas to increase throughput.关键词：multi-user;Orthogonal Frequency-Division Multiplexing;Multiple-Input-Multiple-Output;resource allocation;delayed channel state information
- 2738
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- 0
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发布时间：2023-11-14 - 摘要：Abstract:Aiming at the specificity of pump-valve coordinated control electro-hydraulic actuator (EHA) that valve control loop response higher than pressure loop, the feed-forward fuzzy immune (FFIM) control strategy was applied to the pressure loop control. The position error signal was added to the pressure loop as a feed-forward signal, the dynamic response and control capability of the pressure loop were increased as a result of using optimization immune algorithm and fuzzy algorithm as operator function to adjust PID control parameters in real time. The simulation results showed that the feed-forward signal will increase the response of pressure loop, but will make the pressure value bigger than the setting value, and immune algorithm can effectively reduce the pressure fluctuation around the pressure setting value. So the joint of feed-forward and immune algorithm will not only overcome the high nonlinear and time-varying parameters characters of pressure loop, but also enhance the control capacity of the system.关键词：pump-valve coordinated control;electro-hydraulic actuator;feed-forward fuzzy immune control;pressure control
- 2818
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发布时间：2023-11-14 - 摘要：Abstract: Using a scaler that has a simple geometrical property and adding some restrictions on the movement of the camera, the interior parameters of the camera K,spin matrix R, translational vector T,and direction vector E could be solved successively. The distance was easily measured only by using two images at the different positions on the rail and substituting the known parameters into the distance measuring equation proposed here. This new method overcame the shortcomings of the tradition ways. It need not complex movement of the camera and decrease the difficulty of setting the standard calibration. This method could be used in the field of geological exploration, water conservancy construction, mine exploitation, city planning and large scale equipment manufacturing.关键词：distance measuring;digital image;camera calibration;computer vision
- 2598
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- 2
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- 2
发布时间：2023-11-14 - 摘要：Abstract:The flexibility to the variation of the dynamic effects of the active balancer was obtained by adjusting the speed trajectory of its control motor. Based on the concept of adjustable mechanisms, a method was presented for improving the compensation characteristics on the input torque of the aforementioned balancer. The main point was to let one of the link lengths of the basic linkage of the balancer adjustable. The design procedure based on sensitivity analysis and optimization was developed. By optimizing the length of the adjustable link together with the speed function of the control motor, effective compensation on the dynamic performance under different working conditions can be achieved. A 5R- based active balancer was taken as an example to illustrate the procedure. The results show that the introduction of the adjustable link expands the design space of the balancer for improvement of the dynamic performance, especially the compensation for the input torque and thus brings more flexibility in application.关键词：active balancing;adjustable mechanisms;input torque;sensitivity analysis;planar linkage
- 2497
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- 0
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- 0
发布时间：2023-11-14 - 摘要：Abstract:Aiming at the problem of the identification of cutting tool wear condition, and according to the merit of Hidden Markov Model (HMM) with perfect classifying ability, the system of the tool wear condition monitoring based on continuous Gaussian mixture HMM (CHMM) was presented. With the milling force as the monitoring signal, the wavelet package theory was adopted to analyze and de noise the milling force signal, and extracts energy feature of the signal as import vectors of CHMM, trains CHMM.Then the unknown state of tool wear was monitored and identified using the trained model. The results of the experiment indicated that the model can exactly recognize the tool wear state and need small training samples, has significant realistic meaning to tool intelligent monitoring.关键词：hidden Markov model;wavelet package analysis;milling force;tool wear
- 4122
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- 0
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- 1
发布时间：2023-11-14 - 摘要：Abstract:How to increase the efficiency and the quality of machine tool fixture design is an important research object of computer-aided technology equipment. The reconfigurable modular fixture design integrated of axiomatic design and design structure matrix was provided on the background of planning schedule of reconfigurable fixture modular and modular series. The method emphasized on merging common unit and reusing knowledge and process in fixture design, built relationships between components with design structure matrix so as to construct rational fixture modular structure, and transformed reconfigurable modules to rapidly achieve fixture design. Finally, a case was given to illustrate how to achieve the reconfigurable modular fixture design by the method.关键词：reconfigurable module;fixture design;axiomatic design;design structure matrix
- 2753
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- 4
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- 5
发布时间：2023-11-14
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