最新刊期
卷 41 ， 期 1 ， 2009
- 摘要：Abstract:Pre-stressed anchor cable has been widely used for rock reinforcement in slope engineering for a long time,and the corrosion of steel strand often leads to the failure of pre-stressed anchor cable in special underground environment. Through the fast corrosion experiment by the electro-chemical means and making the pulling test, the elastic modulus change of pre-stressed anchor cable in different corrosion rates was studied.The influence of the wire corrosion characteristic to load transmission was also studied. The result indicated that the steel strand rigidity is degenerated after its corrosion and its elastic modulus weakens following the approximate linear relation with the corrosion rate. Meanwhile, the corrosion of steel strand also influences its load transfer characteristic greatly. In other words, with the corrosion rate increases, the resistance between the steel strand and grouted material will distributes towards the anchor’s front greatly, the peak shear stress will be higher and its distribution also becomes more non-uniform.关键词：pre-stressed anchor;corrosion;electro-chemical means;load transfer;durability
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发布时间：2023-11-28 - 摘要：Abstract:The kernel of stochastic model is the construction of joint distribution or conditional probability distribution. A first-order non-stationary time series model, namely seasonal CAR(1), was established based on Copula function and compared with seasonal AR(1) model. Monthly streamflow data of the Yichang station was investigated and verified by using the proposed seasonal CAR(1) model. Results suggested that the proposed model can preserve the statistical properties of the recorded data series, especially the skew, non-linear dependence and probability density properties, and provides a new way for the study of hydrology and water resources simulation.关键词：Copula function;Markov;stochastic simulation;AR(1) model
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发布时间：2023-11-28 - 摘要：Abstract:Set Pair Analysis(SPA) is a new theory of quantitative analysis for certain and uncertain questions, and discrepancy degree coefficient “i” in connection degree formula is uncertain. In this article the discrepancy degree coefficient “i” is confirmed by Genetic Algorithm(GA),a set pair with “assessed standards” of water quality and “compared standards”is composed. The optimized connection degree formula was applied to assess the water quality of 12 stations in 8 rivers of Sichuan. The results of this assessment, which correspond with the real conditions, are basically in accord with those obtained by Bayes assessment models. In this way, the new effective approaches to the determination of discrepancy degree coefficient “i” and the assessment of water quality are suggested.关键词：set pair analysis;connection number;Genetic algorithm;water quality assessment
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发布时间：2023-11-28 - 摘要：Abstract:The differential equation model of stable isotope composition in saturated soil water at evaporation condition based on the Fick law and the conservation of mass law was proposed. The boundary condition and initial condition were analyzed, and the analytic solution of the differential equation model was obtained. The model provides deterministic mathematic foundation for numerical simulation of saturated soil water stable isotope movement in the condition of evaporation, and are of important theoretical significance for soil water movement.关键词：saturated soil water;stable isotope;differential element method;model
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发布时间：2023-11-28 - 摘要：Abstract:The wastes of mining resources usually have very large quantities, in which the granular size of the wastes is very fine and the moinsture contents or proceesing water are very high. Because of chemical compounds in the processing water, serious environmental problems, surface and subsurface water contaimination will be resulted from the leakage of proceesing water if the stack of the wastes is not treated properly. Due to the key functions of groundwater in the environmental systems, the assessment of tailings stacks on the impact of groundwater will be of great importances. However, structured grid in the numerical simulation models will not be appropriate to match the irregular inner and outer boundaries To evaluate the influences of tailing stacks of mining industries on the groundwater in complicated geological regions，it is necessary to understand the spatial variations of groundwater under the impacts of the tailing stacks. The development of numerical models capable of reflecting the geological complexity, with high stability and accuracy is very important. Therefore, in this paper, a completely implicit finite volume method (FVM) based on unstructured grid systems has been proposed. A case study was carried out in Guizhou province of China. The feasibility and accuracy of the numerical model have been validated through a comparison made between the simulated results and the data of boring holes. The influences of tailing stack in Guizhou on the regional groundwater have been revealed by comparing the spatial differences of groundwater with and without the impact of the tailing stack. Results indicate that the numerical model proposed is adapt for the groundwater simulation or the assessment of pollutants on the regional groundwater.关键词：Unstructured grid, groundwater, contamination, tailings stack
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发布时间：2023-11-28 - 摘要：Abstract:Acoustic Doppler Current Profiler (ADCP) was used to collect water velocity data between Gezhouba Dam and Miaozui. The method of relative velocity was given. Statistical comparisons of cumulative frequency distributions of three-dimensional velocity components were performed using the Kolmogorov-Smirnov (K-S) two-sample test. The results showed that the distributions of three dimensional velocity components of main spawning area are significantly different from those of non- spawning areas. Velocity diversity of spawning area could benefit the increase in fertilization rate of Chinese sturgeon eggs and the protection of its zygotes.关键词：Chinese sturgeon;spawning site;three-dimensional hydraulics;relative velocity;frequency distributions
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发布时间：2023-11-28 - 摘要：Abstract:The air pressure characteristics in a complex tunnel are key factors to the design of the tunnels and need to be studied deeply. In order to enhance the signal intensity and improve the experimental precision, instead of air, water was chosen as the fluid medium and a hydraulic experiment was carried out for complex tunnels with vertical shafts and/or partition wall. Under different velocities, the air pressure processes caused by the train passing through complex tunnels were measured and analyzed。It was demonstrated by the test results that the vertical shafts can obviously decrease the pressure’s peak values and the pressure’s gradients, and the partition wall will worsen the aerodynamic environment. Therefore, if possible, vertical shafts should be chosen and partition walls should be avoided for long complex tunnels.关键词：tunnel;high-speed train;air pressure;water medium model;vertical shaft;partition wall
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发布时间：2023-11-28 - 摘要：Abstract:Based on the relevant research results of the coherent structure, the paper presents the mechanism of sediment transport during the process of turbulent bursting, ejecting and sweeping. Besides, the paper shows the detailed process of how a straight channel, due to the sediment particles moving from side walls into the water channel, changes into ith alternate side bars, and eventually into a meandering channel. Further, the paper presents the proposed critical incipient motion condition of the particles on the side wall by analyzing the forces exerted on the particles and be applying the turbulent eddy theories. The incipient motion condition is applied in Yellow River. The study showes that increasing bed roughness and flow depth are more helpful to the incipient motion of the sediment.
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发布时间：2023-11-28 - 摘要：Abstract:While predicting reservoir temperature numerically, flow field and pressure field were obtained and rectified orderly at each time step with a low efficiency in traditional SIMPLE algorithm procedure. According to the theory of SIMPLE pressure correction, this paper treated coefficients matrix preparing and governing equations resolving as well as velocity and scalar equations side by side and the parallel mechanism was applied to the laterally averaged 2-D reservoir water temperature model. The parallel result calculated on a Intel 4-core processor showed a good agreement with the serial and the parallelism improved the calculation performance efficiently with its speedup index reaching 1.5.关键词：parallelism;water temperature predicting model;SIMPLE algorithm
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发布时间：2023-11-28 - 摘要：Abstract:The effect of blast-induced seismic waves on buildings can be considered as a transferred and transformed process of the energy, which relates to the energy distribution characteristic of blasting vibration. An energy analysis method for blasting vibration signals based on power spectrum was put forward. Based on a large number of measurement data, the energy distribution characteristics of seismic waves induced by different forms of blasting resource were studied. The result shows that for blasting vibration induced by four kinds of drilling-and-blasting, the energy distribution with frequency is scattered. The seismic energy of low-frequency from 0 Hz to 10 Hz is very little. The energy distribution characteristics vary with the different types of drilling-and-blasting. As diameter and depth of the blasting hole increases, the frequency band of energy distribution becomes more focus and has the trend of moving to the lower frequency, and for underground blasting, the seismic energy below 40 Hz is very little. The energy distribution characteristic of seismic waves induced by different forms of blasting resource can have guiding role for choosing the appropriate type of drilling-and-blasting when the effect of blasting vibration needs to be controlled.关键词：blasting vibration;energy distribution;power spectrum;drilling-and-blasting;control blasting
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发布时间：2023-11-28 - 摘要：Abstract:In order to investigate the flow characteristics in circular settling tanks with or without temperature difference, a k-epsilon two layer turbulence model was developed for this problem. In the numerical process, staggered grid system was employed, pressure and velocity were decoupled using SIMPLE method, and the hybrid finite analytic method was used to solve the governing equations. The simulation results of circular settling tanks with inlet at the center and outlet at the skirt show that the simulation results were in line with the results available in literatures. Without temperature difference and low suspended solids SS<150-200mg/L, there was a big recirculation region. It could cause gravity flow, if low density flow entering into the tank, while it could cause buoyant flow if high density flow entering into the tank.关键词：Circular settling tanks;Density current;Turbulent flow;k-epsilon two layer model;Hybrid finite analytic method
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发布时间：2023-11-28 - 摘要：Abstract:According to the numerical simulation method of initial stresses filed,and based on the assumptions that vertical initial stress is equal to gravity stress of rock masses, and two direction horizontal initial stresses are not equivalent an initial stresses field back analysis method which used the object of the excavation relative displacement ratio and the excavation relative displacement increment ratio for shallow tunnel was put forward.Through a back analysis example of a shallow tunnel, the results showed that, this back analysis method is simple and easy operation; the results is rationally and accord to the engineering fact.关键词：rock mechanics;Tunnel;excavation displacement;back analysis;initial stresses filed;lateral earth pressure coefficient
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发布时间：2023-11-28 - 摘要：Abstract:During the research of hydraulic structure model test，the displacement and strain of dam body and dam foundation are mainly measured by displacement transducers and foil resistance strain gauges on the surface．For the internal deformation of model under overloading，it will be difficult measured accurately with conventional monitoring instrument．In the research，based on gravity dam section，fiber grating sensors were installed in dam body and dam foundation，the internal displacement of structure model after overloading was monitored，as well as displacement transducers and foil resistance strain gauges on the surface. Through the comparison analyses of monitoring result of deformation for dam body and dam foundation measured by the fiber grating sensor and displacement transducers，the displacements measured using the fiber grating sensor are in good agreement with those from displacement transducers. The feasibility of the application of fiber grating sensor in gravity dam structure model test was confirmed．The test results reveal the overloading coefficient is 6.0，and the failure mechanism of the gravity dam structure model was obtained．The success application of optical fiber grating sensor in hydraulic structure model test will help sufficiently us to find out the internal deformation of dam body and dam foundation under overloading．关键词：structure model;internal deformation;monitoring;optical fibre grating sensor;overloading method
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发布时间：2023-11-28 - 摘要：Abstract:The factors which control and affect sand liquefaction, are random and uncertain. Because artificial neural network can consider both quantitative and qualitative factors, it is suitable for solving uncertain problem of the evaluation of sand soil liquefaction. A generalized regression neural network model for evaluating sand liquefaction hazard degree was established based on the basic principles and algorithms, and was trained and checked with the collected sand liquefaction examples and compared with results obtained by the BP neural network. The results show that the generalized regression neural network model presents excellent network performance, high prediction accuracy, and is an effective way to evaluate the sand liquefaction hazard degree.关键词：generalized regression neural network;sand liquefaction;hazard degree;evaluation
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发布时间：2023-11-28 - 摘要：Abstract:Yichang low-water level was an important parameter connected with the operation of Gezhouba ship lock. It had kept stable while a huge amount of sediment erosion had been caused during TGP’s (Three Gorges Project) initial impoundment period, and its reason wasn’t very clear now. Analysis of the riverbed boundary condition changes was presented in this paper, and it showed that the stable planmetric figure, function of the bottle-neck reach, non-uniformity of the bed erosion, increase of the bed resistance were the main reasons for the stability of Yichang low-water level. Because of the function of the bottle-neck reach, there would be no big fall of low-water level at Yichang station.关键词：Yichang low-water level;bottle-neck reach;TGP water-storage;river-bed scour
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发布时间：2023-11-28 - 摘要：Abstract:〗Distinct Element Method of UDEC was used to simulate the stability of gravity dam against deep sliding. Fluid-solid coupling effect was considered. Dam’s stress and displacement were then gained before and after reducing the strength of the base materials. The safety factor and the sliding mode of the dam were gained. Variations of stress and displacement of key points were taken records,and its charateristics were studied.The UDEC considering fluid-solid coupling were compared with that not considering coupling,the resulte of UDEC not considering fluid-solid coupling are too large and not correspondent with practice. Finally the results were compared with the rigid body limit equilibrium method. Numerical results showed that the Distinct Element Method of UDEC is reliable and feasible, and can increase the calculation efficiency.关键词：fluid-solid coupling;distinct element method;gravity dam against deep sliding;UDEC;rigid body limit equilibrium method;strength reserve coefficient method
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发布时间：2023-11-28 - 摘要：Abstract:In order to establish an elastoplastic stress strain model for soil which conforms to the actual situation,an elastoplastic endochronic constitutive model was developed incorporating the multi hardening mechanisms and the interaction between deviatoric and volume deformation by means of properly defining a generalized time scale. Since it has been revealed by experimental results that volume deformation response has little effect on deviatoric deformation response,while deviatoric deformation response has strong effect on volume deformation response, the parameters in this model to characterize the soil behaviors can be determined from the results of isotropic compression and conventional triaxial compression experiments. The comparison between the predicted and measured stress strain and volume change behaviors for medium density sand from Yongding River showed that the model was capable of predicting the soil’s shear compression and dilation characteristic with good accuracy.关键词：soil;elastoplasticity;hardening mechanism;endochronic constitutive model;dilation
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发布时间：2023-11-28 - 摘要：Abstract:In order to study the water sensitivity of high liquid limit soil and coal bearing soil which ranges along with Guangwu Highway, their shear strength were measured through direct shear test,the influence of water contents on the shear strength of coal-bearing soil was comparatively analyzed and some strategies for treeting the high liquid limit soil and coal bearing soil were discussed. The results indicated that the shear strength and initial water content of high liquid limit soil and coal-bearing soil have marked correlationship and the bigger their initial water content, the smaller their shear strength. With water content increasing, the interrelationship between the logarithm of cohesion of high liquid limit soil and its water content is linear, while its internal friction angle firstly declines by small margin and then sharply declines. With water content increasing, the changing trend of cohesion of coal-bearing soil is of marked characteristic of stage: when water content of coal bearing soil is under some value, its cohesion changes in small ranges; after water content of coal-bearing soil is over the value, its cohesion decreases with water content increasing and the interrelationship between the logarithm of its cohesion and water content is linear. Water content of coal-bearing soil has no marked effect on its internal friction angle. High liquid limit soil and coal-bearing soil have different water sensitivity mainly because of the difference of their gain size composition.关键词：road engineering;special soil;direct shear test;water sensitivity;shear strength
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发布时间：2023-11-28 - 摘要：Abstract:A comparative study of the bilinear, biquadratic quadrilateral element and quadratic triangular element for solving incompressible viscous flows was presented. These elements make use of the Galerkin/Least squares(GLS) stabilized finite element formulation, in which the pressures and velocities are interpolated with the equal orders. The Newton–Raphson algorithm was employed in solving the nonlinear FEM equations. All formulae needed for calculating the tangential matrices are derived in details in a form to be easily programmed. Using the method proposed, the numerical solutions of lid–driven cavity flow for Reynolds number of 1000, 5000, 10000 and 20000 are obtained, and the accuracy and converging rate of results from the different elements are compared. The numerical example shows that the quadratic triangular element exhibits the best comprise between the accuracy and convergence rate compared to the other two elements.
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发布时间：2023-11-28 - 摘要：Abstract:An ultrasonic guided wave nondestructive testing system was assembled. Two fully grouted rock bolts with a length of 1m and diameter of 0.11 m were made. The uniaxial compressive strengths of the grouts were 4.69 MPa and 4.36 MPa, respectively at 28 days. The velocity variations of ultrasonic waves propagating along the two grouted rock bolts were tested using the system at different curing- time and different frequencies (from 40 kHz to 100 kHz), to study effects of curing time and frequencies in the low-strength grouted rock bolts. The results showed that the guided wave group velocity increased with frequency in the testing frequency range and the growth rate reached 10.1% and 8.2%, respectively. Curing- time also had a great impact on the guided wave velocity, especially in the early time. During the first 7 days of curing the guided wave velocity had a significant decrease and the biggest drop of 29.4% was recorded. But the change of wave velocity was not obvious after 7days, just a slight increase. The experimental results fully agreed with the theoretical analysis.关键词：grouted rock bolts;ultrasonic guided waves;non destructive testing;grouted intensity
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- 100
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发布时间：2023-11-28 - 摘要：Abstract:See to the fact that normal serial genetic algorithm handling dynamic optimization problem is not efficient enough, parallel genetic algorithm is suggested to solve this problem, and a new adaptive migration operator is proposed. Combining this adaptive migration operator with adaptive crossover operator and mutation operator of serial genetic algorithm, the adaptive bi oriented migration coarse grained parallel genetic algorithm which uses ring topology is implemented within a 4 processor COW environment. The fuzzy model of normal dynamic optimization is established for describing the real engineering problems more practicaly, the genetic coding method of calculating the optimal fuzzy level value λ* is presented, which can solve fuzzy model more conveniently. The two examples of the last are given to demonstrate the efficiency of the adaptive parallel genetic algorithm and certificated that the fuzzy optimization model is better than the normal optimization model, which is more practical and effective.关键词：adaptation;paralle genetic algorithm;dynamic optimization;fuzzy method;optimal fuzzy level value λ*
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发布时间：2023-11-28 - 摘要：Abstract:Based on the model of stiffened plates with concentrated added mass, a study of the stochastic vibration was carried out, and system’s mean value, mean square value, cross-correlation function, cross-spectral density function were calculated. Two mathematical models of active control were proposed and compared on the basis of simulating the system vibration. Minimum acceleration method and minimum power transmission method were employed to investigate the control effects under random forces. The result showed that the presented methods could control the stochastic vibration effectively. The optimal position and magnitude of the control forces could also be figured out if the stimulant forces and the reference points were known, providing a basis for the practical project.关键词：stiffened plate vibration;stochastic vibration;concentrated added mass;active control;minimum acceleration control;minimum power transmission control
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发布时间：2023-11-28 - 摘要：Abstract:On the basis of the hypothetic displacement field, various parameters of the box girder section are concentrated in the structural axis, and the displacement model of the generalized degree of freedom is built based on the mechanical character of the box girder.In this case, three dimensional space structures can be simplified as one dimensional structure, and the element of the thin walled box beam can be obtained.Theories of the element take account of the mechanical character of the thin walled box girder structure based on the basic beam theory, which improved significantly the calculation accuracy of the thin walled box beam structure. In addition, the results of the engineering application based on this paper and space grillage analysis method validate that this theory is exact and simple, and it offers a practical and simple way to solve the analysis problem with complex thin walled structure.关键词：bridge engineering;element of thin walled box girder;displacement field of mechanical character;generalized degree of freedom
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发布时间：2023-11-28 - 摘要：Abstract:In order to investigate the working behaviors of bonded rebar under fire (high temperature), 25 specimens were designed for the test of pullout strength including those working in the ambient circumstance.Two embedment depths (10 d, 15 d) were considered. Records were made on the temperatures inside the specimens,bonded rebar displacements and the pullout strengths. The pullout strengths of 10 d and 15 d specimens at different temperatures were analyzed and contrasted the pullout strength of 15 d specimens with that of 10 d specimens at the same temperature.The tests showed that the pullout strength decreases when the specimen is under high temperature. Especially, when the temperature is above 350 ℃, the pullout strength is about 10%~20% that of the ambient circumstance.关键词：bonded rebar;High temperature;embedment depth;pullout strength
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发布时间：2023-11-28 - 摘要：Abstract:In order to investigate the treatment efficiency of intetrated MBR for chemical industry wastewater treatment, an 80m3/d full-scale internal circulation integrated MBR with particle carriers was used to treat chemical industry wastewater for about one hundred days. The results showed that when the influent concentration of CODCr, NH3-N and TP were 153.20~594.68mg•L-1, 2.02~23.79mg•L-1 and 3.36~13mg•L-1, respectively. The water quanlity of effluent was stable after 90 days’ operation performance.And the effluent concentration of CODCr, NH3-N and TP were lower than 50mg•L-1,3mg•L-1 and 1mg•L-1, the removal were 80.25%~87.15%, 73.32%~99.78% and 87.09%~93.82%. The color and pH value of effluent were 25~40 times and 6.79~7.83. And the effluent was clear and without stimulated smell. The treatment efficiency of membrane bioreactor was improved by adding particle carriers, which continuously scoured and collidded membrane surface, resulting in alleviating membrane fouling.关键词：membrane bioreactor(MBR);particle carriers;internal circulation;aerobic;anoxic
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发布时间：2023-11-28 - 摘要：Abstract:Based on experimental study, through the analysis of composite beam’s the second molding and the second stage force,and considering the ownlinearity of material,nonlinear finite element program for steel fiber reinforced concrete(SFSC) composite beams was compiled with Viusal-Fortran language. By using the program, the entire failing process of the steel fiber reinforced concrete(SFSC) composite beams was simulated from initial loading, cracking, yielding to failing. The stimulation results corresponded well to the experiment results by contrast calculation results with experimental results. Meanwhile,the mechanical behavior of steel fiber reinforced concrete(SFSC) composite beam after the introduction of steel fiber was studied.The results indicated that steel fiber can remarkably resist crack propagation extent with the increment of the steel fiber content, and it can reduce the phenomenon of tensile steel stress increasing rapidly for composite beam. Finally, by constructing DXF format graphics conversion file, the program can partially realize computer simulation for entire failing process of fiber reinforce concrete composite beam.关键词：steel fiber reinforced concrete;composite beam;nonlinear finite element;DXF;computer simulation
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发布时间：2023-11-28 - 摘要：Abstract:Startup experiments of hydrogen bioproduction CST reactor were conducted. The molasses was used as substrate and different types of seed sludge were utilized. The results indicated that initial microbe community is one of the crucial factors on reactor’s startup speed. At medium temperature 35±1℃, hydraulic retain time（HRT）about 9h, organic loading rate (OLR) between 8~10kgCOD/m3﹒d, aerobic activate sludge, anoxic activate sludge and anaerobic activate sludge can be used as seed sludge. The startup times are 35d, 25d and more than 50d respectively. Anoxic activate sludge is the optimal seed sludge for rapid startup of hydrogen bioproduction CST reactor.关键词：startup,seed sludges,hydrogen bioproduction reactor
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发布时间：2023-11-28 - 摘要：Abstract:Using PMRM to determine the partition probability and calculating the conditional probability within the given partition probability, the risk function was derivated and imbed in risk decision model to make decision. In Eping CFRD construction in Hubei province, the application of PMRM can make a reasonable decision.关键词：anti-flood measure;risk;splitting probability;PMRM
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发布时间：2023-11-28 - 摘要：Abstract:The Tanning Matrix can be formed by resorcinol and oxazolidine E, and the reaction properties between Tanning Matrix and collagen has been investigated through NMR and size distribution analysis. The collagen was simulated with glycin. The results have showed that the molar combination ratio of Matrix as congeries between oxazolidine E and resorcinol was 2:1 or 3:2, the reaction positions were C(5) and C(6) of oxazolidine E and C(4) or C(6) of resorcinol. And the hydroxymethyl of oxazolidine E and amino group of collagen bonded with covalent bond, phenol hydroxyl group of resorcinol and amino group of collagen combined with hydrogen bond.关键词：resorcinol;oxazolidine E;glycin;ternary reaction
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发布时间：2023-11-28 - 摘要：Abstract:The linear error propagation and its system matrix of the spatial discretization of matrix SPH, which was derived through perturbation method, were used to analyze the stability of SPH. Based on the linear form, the sufficient condition, which was ever obtained by Swegle, was also derived. Omitting the effect from the continuity equation and analyzing the characteristic equation of the system matrix, two matrixes, which having equivalent eigenvalues to those of the system matrix, were obtained and could respectively represent the existences of the tensile instability and the high frequency instability (HFI) in SPH. Based on the matrix that represents the existence of tensile instability, the tensile instability was found to be sensitive to the phase differences among the errors on particles. Based on other matrix that represents the existence of HFI of SPH, the origin of HFI, i.e. the rank deficiency in stiff matrix, was further found to be correlated with the asymmetry of the stiff matrix induced by the heterogeneous particle volumes. At last, another smoothing length refreshing model was proposed and was tested in two numerical cases.关键词：SPH;space discretization error;system matrix;tensile instability;high frequency instability
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发布时间：2023-11-28 - 摘要：Abstract:On a new torsional fretting tester， the torsional fretting tests of polymethylmethacrylate （PMMA）flat against GCr15 steel ball (with diameter of 40 mm) were carried out with various angular displacement amplitudes from 1° to 30° and imposed a normal load of 100 N. Base on the analysis of the frictional kinetics of torsional fretting， the damage characteristics of PMMA also were discussed in detail. The results indicated that the behaviors of torsional fretting were strongly depended upon the angular displacement amplitudes and the number of cycles， which can be characterized by the curves of friction torque / angular displacement (T-θ).Tow kinds of T-θ curves (i.e. parallelogram and elliptical curves) were observed during the process of torsional fretting. Along the radial direction，the wear scar could be divided to three zones， i.e. the adhesive zone，micro-crack zone and severe damage zone， respectively. The damage of torsional fretting at lower angular displacement amplitude was very slight. And increased with the angular displacement amplitude， the spindle-like shape pits distributed along radiating patterns from contact center can be observed. The result of debris determined by gel permeation chromatography (GPC) showed that the molecular weight of PMMA decreased during the torsional fretting occurred .The wear mechanism performed as delamination and crack.ing.
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发布时间：2023-11-28 - 摘要：Abstract:The influences of Fe3+，Al3+，F-，SO42-ions on the crystallization process of ammonium dihydrogen phosphate(MAP) were studied by means of batch crystallization process.The results showed that the dopant of Fe3+，Al3+ had siginificate effect on MAP crystallization process, which made the crystal shape changeing from prism to spiculate; with the increase of dopant, the metastable zone width(MZW) increased, the crystallization induction period increased obviously, the crystal growth rate decreased and the average crystal size decreased; With the increase of Mg2+, the metastable zone width widened, the average crystal size and l∶ddecreased; The existence of F- widened the metastable zone, minished the ratio of length to diameter of crystal.shape changed the crystal from long prism to short prism;The effect of SO42- on crystallization process was neglectable. The experiment results are quite valuable to MAP production.关键词：ammonium dihydrogen phosphate;impurity;crystal;metastable zone width
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发布时间：2023-11-28 - 摘要：Abstract: Hydrophobically modified polyacrylic acids (HMPA) was synthesized by precipitation polymerization. HMPA in ethylene glycol-water mixture show typical shear thinning behavior. It was found that the solvent have a direct impact on the rheology behavior of HMPA in ethylene glycol-water mixture, due to the changes in hydrophobic associations. Surfactant TX-10 induced factors that change the number and strength of hydrophobic junctions and lead to change of solution visicosity. The transient associative network of HMPA in ethylene glycol-water mixture was kept as the temperature decreases.关键词：association;poly (acrylic acid);rheology;ethylene glycol;surfactant
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- 1
发布时间：2023-11-28 - 摘要：Abstract:The adsorption behaviors of Cr(VI) on collagen fiber immobilized bayberry tannin(IBT) , a new kind of adsorbent, were investigated. It was found that the adsorption capacity of Cr(VI) increased with the decrease of pH value. At the pH 2.0 and temperature of 303 K, the adsorption capacity of Cr(VI) on 0.100 g adsorbent was 78.5 mg·g-1in 100 ml of 100.0 mg Cr(VI)·L-1 solution, and decreased with the raise of temperature. The adsorption isotherms could be well described by the Freundlich equation. The adsorption kinetics investigations indicated that the adsorption rate of Cr(VI) on IBT could be well described by the pseudo-second-order rate model, and the adsorption capacities calculated by the pseudo-second-order rate model were closed to measurements. The adsorption mechanism investigations indicated that the adsorption of Cr(VI) on IBT was a redox process. It could be consisted of two reaction steps: firstly Cr(VI) being deoxidized to Cr(III), and then reduced Cr(III) combining with —COO— or the adjacent hydroxylphenyl groups in IBT.关键词：couagen fiber;immobilized tannin;adsorption;Cr(VI);adsorption mechanis
- 2624
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- 98
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- 1
发布时间：2023-11-28 - 摘要：Abstract:Evolvement of bubble size distribution of aluminum foams with different bubble structure models is studied based on the MacPherson’s theory for coarsening of three-dimensional microstructures. Numerical predictions reveal that the changing way of the foam’s mean volume follows the relationship , which agrees with MacPherson. It is found that the foam’s structure model has a dramatic effect on the bubble mean volume change, i.e., bubbles with cubic form are shrinking with time, while bubbles with icosahedrons form will be coarsening. Surface tension plays a dominative role in the changing processes of bubble volume distribution of foams.
- 2286
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- 304
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- 0
发布时间：2023-11-28 - 摘要：Abstract:The bubbles produced by a microporous sparger (Dp=40 μm) and a single orifice sparger (Dp=1 mm) at superficial gas velocities ranging from 0.629×10-3 m·s-1to 3.15×10-3m·s-1 were compared in the oxygen cyclohexane system. The results showed that the Sauter mean diameter d32 of the bubbles produced by the microporous sparger were below 1.3 mm, and those by the single orifice sparger were larger than 4.0 mm. The diameters of the bubbles produced by the microporous sparger met the logarithmic normal distribution, and the coalescence of the bubbles was negligible. The gas hold up of the microporous sparger bubbling was relatively higher in the examined superficial gas velocity range. By using the microporous sparger, an cyclohexane oxidation rate of 0.62 mol·m-3·s-1 at a superficial gas velocity of 1.15×10-3 m.s-1 was achieved, which was about 1 fold higher than that performed by using the single orifice sparger.关键词：cyclohexane;liquid-phase oxidation;oxygen;microsparger
- 3105
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- 112
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- 0
发布时间：2023-11-28 - 摘要：Abstract:The characteristics and cytocomptibility of genipin-fixed porcine aorta were investigated in vitro to provide the proper biomaterials for fabrication of esophageal prosthesis. The porcine aortas were treated by genipin for 7min to 7day. The biological materials fixed with genipin were then examined with naked-eye and light microscope. Subsequently, the fixation index determination, the biomechanics test, in vitro enzymatic degradation and denaturation temperature measurement were also performed. The cytocomptibility of the genipin-fixed materials was evaluated in vitro by MTT assay using human esophageal epithelial cells as test cells. The experimental results indicated that the antigenicity of porcine aorta tissues could be diminished by genipin through getting rid of cell in the porcine aorta tissues or reducing the level of free amino groups in the porcine aorta tissues. The structural integrity of porcine aorta tissues can be preserved after treating with genipin. It was also found that the genipin-fixed porcine aorta tissues appeared more toughness and visco-elasticity, and should be a promising material for fabricating esophageal prosthesis. The genipin-fixed porcine aorta tissues were provided with a high ability to resistance against enzymatic degradation that made this material suitable to be an implant material. The genipin-fixed porcine aorta tissues showed a good cytocomptibility that the human esophageal epithelial cells could proliferate well on it. Among the porcine aorta tissues fixed with genipin, the tissues that were fixed at pH 4.0, 0.625g/100ml initial fixative concentrations for 7 day showed a more favorable characteristic. In conclusion, the Genipin-fixed porcine aorta should be a promising material for fabricating esophageal prosthesis or fabricating scaffold of tissue-engineered esophagus.关键词：Genipin;Porcine aorta;Fixation;mechanical properties;Cytocomptibility
- 2475
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- 250
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- 1
发布时间：2023-11-28 - 摘要：Abstract:In this paper, Polydodecylmethacrylate-2-ethyl hexyl acrylate resin was synthesized by means of microwave irradiation. Morphologies and textural properties of the synthesized resins were characterized by using Scanning Electron Microscopy (SEM). Adsorption of oil fume on the resins synthesized was measured. The effects of monomer ratio, initiator dose, dispersant dose, and cross-linker dose as well as synthesis reaction temperature on the synthesized resin adsorption of oil fume were investigated. Results showed that when the monomer ratio (2-ethyl hexyl acrylate /dodecylmethacrylate), the initiator dose, dispersant, and cross-linking agent dose were respectively 3:7, 1%,1.5%, and 0.6%, the synthesized resins had a developed porous structure and its maximum amount adsorbed of oil fume was available. In comparison with synthesis method of traditional water-bath heating, the use of microwave irradiation can improve conversion efficiency of synthesis reaction, and greatly shorten synthesis reaction time from 6h to 2h. The WR resin synthesized by using microwave irradiation had higher adsorption capacity of oil fume compared to the NR resin synthesized by traditional water-bath heating method.
- 2581
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- 276
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- 1
发布时间：2023-11-28 - 摘要：Abstract:For termination of linear loop programs proposed by Tiwari,the proof that the non linear programs of cycle conditions is the homogeneous polynomial and can not be terminated was put forward.Then the program termination was transformed as the solution of a system of semi algebra.A powerful algebraic symbols tool DISCOVERER was used to solve the approximate error caused by floating point calculations, and accurately determinate that such programs can not be terminated. Finally, by the computation algebra theory,the cycle conditions was extended to non homogeneous polynomial.Through theoretical and experimental proof, for a kind of cycle programs that cycle condition is non linear,these solutions is efficient and reasonable.关键词：nonlinear programs;termination;program verification;Jordan form
- 2731
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- 482
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- 3
发布时间：2023-11-28 - 摘要：Abstract:PI-1 and PI-2 polyimide films were prepared from 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) and ODA确良by two-step polymerization under the thermal and mixed imidization procedures. PLM showed that the PI-1 film was amorphous and PI-2 film had a similar "well" texture and the typical black cross extinction of the morphology of spherulite. The diameter of the spherulite was 0.02 mm to 0.03 mm. At the same time, from the phase diagram of AFM on PI-2 film，as chains in an regular arrangement, there were two parts of bright and shade, which proved that the existence of the a nonrandom structure. From WAXD, the order degree of PI-2 film was higher than that of PI-1 film. SAXD showed that, at 2θ= 3.115°, there was a small diffraction peak from the polyimide film, which is correspondent to a nonrandom samdwich with the layer spacing d=2.83 nm.The reason was that the PI segmers got from mixed imidization procedure form crystal nucleus which let the molecular chains regularly stack.关键词：3,3′,4,4′-benzophenone tetracarboxylic dianhydride;polyimide;mixed imidization;aggregation structure
- 2847
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- 78
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- 0
发布时间：2023-11-28 - 摘要：Abstract:In order to improve the expressiveness of Kleene algebra with tests (KAT), which formalizes the behavior of regular programs, a complete theory of probabilistic Kleene algebra with tests (PKAT) for reasoning regular programs with probability was proposed. A model termed probabilistic configuration transition systems was proposed,which are composed of a pair of a PKAT expression and a data state. Operational semantics for PKAT based on the model was put forward, and a probabilistic bisimulation equivalence relation in PKAT was established. The soundness of the equations of PKAT was validated with respect to the bisimulation.关键词：PKAT;probabilistic configuration transition systems;structural operational semantics;bisimulation
- 2633
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- 486
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- 0
发布时间：2023-11-28 - 摘要：Abstract: Traditional algorithms based on graph theory were sensitive to the brightness of image, the time complexity was high, and in order to improve its segmentation effect, a new threshold segmentation algorithm, based on characteristics of human brightness perception, was proposed.This algorithm used the Normalized Cut criterion, and combined with graph theory and LIP (Logarithmic Image Processing) model. Meanwhile the algorithm utilized both intensity and position of information, had holistic character and its time complexity was acceptable. The experiments illustrated that the algorithm could more effectively distinguish an object from the background than traditional techniques, even in the condition of small changes in scene illumination.关键词：normalized cut;logarithmic image processing model;weight matrix;graph theory
- 3027
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- 186
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- 0
发布时间：2023-11-28 - 摘要：Abstract:The particle swarm optimization (PSO) is a stochastic population-based optimization technique that is gaining popularity. However, it may be trapped in local optima and fail to converge to global optimum, especially for multimodal and high-dimensional problems. Many variations of PSO were aimed at the phenomenon of prematurity, but most of them added complexity to the paradigm and made PSO harder to be understood. In this paper, the evaluation of a particle’s position was investigated, and it was proposed that the evaluation strategy in standard PSO had two shortcomings, i.e. “two steps forward, and one step back” and “two steps back, and one step forward”. A novel evaluation strategy with the same convergence analysis as the standard PSO was presented, whereby each particle was evaluated in dimension-by-dimension order so as to step steadily toward the aimed position, and experiments showed that the novel strategy was very promising for multimodal and high-dimensional problems. A general evaluation strategy was defined, and experiments showed that the number of grouping could balance effectively the convergence speed and the best fitness so to get excellent performance.关键词：particle swarm optimization;Evaluation strategy;Swarm intelligence;Convergence behavior
- 2570
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- 306
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- 0
发布时间：2023-11-28 - 摘要：Abstract:Aiming at complex environments and the situation without any pose information of robots, a novel approach to multi-robot cooperative map building was presented. The approach let all robots operate individually and then tried to merge the different local grid maps into a single global one. Without using any relative pose information of robots, the process of map merging was performed by measuring the similarity between grid maps. Distance transforms and an improved genetic algorithm were used to effectively search the maximum overlap at which the local maps can be joined together. Furthermore, considering the situation that there may be no overlapped area among local maps, a value function was introduced to judge the merging results. Experimental results showed the feasibility and effectiveness of the present approach in complex environments.关键词：multi-robot;complex environments;map building;distance transform;Genetic algorithm
- 2601
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- 112
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- 0
发布时间：2023-11-28 - 摘要：Abstract:The AKS algorithm successfully solved the noted problem of deterministic primality testing in polynomial time, but it was not yet suitable for the real application, thus it was improved in series. In order to further analyze the practical efficiency of currently improved versions of the AKS algorithm, one of them (called the second AKS Bernstein algorithm), which was proposed by Bernstein, was implemented by using Delphi Pascal program on PC Pentium I V/1.8 G, and its running efficiency were compared with that of other versions. For data that formerly needed tens or thousands of hours to complete the primality test with previous versions, only several seconds were required when running with the second AKS Bernstein algorithm. Thus, the conclusion that the second AKS Bernstein algorithm is better than other improved versions was got. In addition, some defects of the second AKS Bernstein algorithm were analyzed, and the suggestion that the second AKS Bernstein algorithm remains to be improved was made.关键词：primality testing;AKS algorithm;Rabin Miller test;implementation of an algorithm
- 3364
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- 532
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- 0
发布时间：2023-11-28 - 摘要：Abstract:An automatic and efficient edge blending method was presented to improve the imagery quality of multi-projectors display system with anomalistic and multiple overlap regions. Using the pixel-level geometric calibration,the edge blending problem was formulated as a non-linear optimization problem with the object function being the global consistency of brightness distribution. An iterative computing method accelerated by GPU was presented to solve such optimal problem. The theoretic analysis was carried out to demonstrate the importance of enlarging the region of edge blending. Real applications showed that the proposed method can make the multi-projectors jointly display a visual seamless imagery with anomalistic and multiple overlap regions and maximize the edge blending regions by using all pixels of projectors.关键词：edge blending;anomalistic overlap region;nonlinear optimization;GPU acceleration;brightness distributing
- 3511
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- 104
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- 0
发布时间：2023-11-28 - 摘要：Abstract:Optimization digital circuit is a focus of Evolutionary Hardware (EHW). A new algorithm of optimizing the complex circuit by using parallel gene expression programming (COPGEP) was proposed. In this algorithm, the better individuals were migrated among the sub-populations and the better individuals were transferred to next generation effectively. This algorithm sufficiently exerted the oriented effect of the better individuals to enhance the precision and convergent speed. The experiments showed that this algorithm had not only faster convergent speed but also could overcome more faults, compared with traditional GEP, in which the convergent speed was slow, even no convergence when the variables of logic gate circuit were more than five.关键词：gene expression programming;parallel algorithm;Evolutionary Hardware;optimization circuit
- 2879
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- 118
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- 0
发布时间：2023-11-28 - 摘要：Abstract:To correctly recognize the intersecting curves in curve graphs used in many industries such as petroleum geology,image understanding theory was applied to judge which two intersecting branches belongs to the same curve, and the method of choosing the optimum combination was used to get the best fitting group. First the characteristic points of each branch were chosen. Then the branches were combined as different groups. Next the method of least squares function was used to fit the curve of different combinations. After that, the windages between fitting curve and characteristic points were calculated and compared in different groups. The combination that has the minimal windage was the best result. Experiments showed that the method works effectively.关键词：intersection;image understanding;curve fitting;choosing the optimum combination
- 2837
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- 458
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- 0
发布时间：2023-11-28 - 摘要：Abstract:In order to study the effects of time-varied uncertainty of the sampling period on control performance and network performance in the networked control system,an intelligent dynamic scheduling strategy was proposed based on feedback control and prediction mechanism.In this strategy, network resources utilization and deadline miss rate, and IAE were used as feedback control scheduling to schedule messages. BP neural network was used to predict the network resource utilization and data packet execution time to adjust the sampling period and improve the network performance. The simulation results showed that the scheduling algorithm not only met the control performance, but also improved the utilization of network resources.关键词：networked control systems;variable-sampling period;intelligent dynamic scheduling;BP neural network;feedback control
- 2576
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- 140
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- 0
发布时间：2023-11-28 - 摘要：Abstract:Mobile phone with limited system resources, if Tibetan Unicode coding is directly used, and the assembling method is adopted to generate Tibetan character, the time complexity of system processing will greatly increase, therefore, a new Tibetan coding rule for mobile phone based on analysis of Tibetan character and Tibetan Unicode coding, as well as use index technology was presented. Mobile phone keyboard keys are limited, one-on-one arrangement for Tibetan alphabet can not be carried out, so that a scientific mobile phone keyboard layout that utilizes Tibetan grammar and index technology was designed on limited keyboard keys. A Tibetan SMS coding and decoding methods that corresponds to Tibetan coding rule for mobile phone was devised.关键词：Chinese information processing;Tibetan;mobile phone;coding;keyboard layout
- 2495
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- 504
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- 0
发布时间：2023-11-28 - 摘要：Abstract:A novel Quiescent Pattern Control(QPC) approach was proposed for airborne radar weak signal detection in strong space time clutter environment. The new QPC approach imposed quadratic beampattern constraints in the adaptive processing and exploited the Taylor series approximation to estimate the solution. Adaptive processing was restricted to a Localized Processing Region(LPR) in the transform domain thus an improved rank reduced beamspace space time adaptive processing architecture was obtained. In the architecture, the blocking matrix consisted of angle Doppler bins surrounding the bin of interest. The proposed approach was combined with the improved reduced rank beamspace Space Time Adaptive Processing (STAP) techniques to obtain a robust STAP method. The approach can cancel clutter while maintain low sidelobe more efficiently. It had low sample support requirement and strong robust implementation. It can also decrease computation load efficiently. Performance analysis was carried out using simulated data. The results proved the effectiveness of the proposed approach.关键词：airborne radar;clutter suppression;space time adaptive processing;beamspace;Quiescent Pattern Control(QPC)
- 2236
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- 472
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- 2
发布时间：2023-11-28 - 摘要：Abstract:In order to resolve the extraordinary complexity of safety in the Usage Control models(UCON), the safety of ongoing authorization UCON models(UCONonA) was analyzed. A formal UCONonA model was presented based on the attribute mutability and decision continuity characteristics of UCON through the strategy or pattern definition and state transition. It was concluded that it is undetermined for the safety problem of a general UCONonA model according to the analysis. It can be proved that the safety of UCONonA models is decidable while its attribute domains are finite and there aren't creating actions in the scheme.关键词：access control;usage control (UCON);authorization;continuity;mutability
- 3170
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- 104
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- 2
发布时间：2023-11-28 - 摘要：Abstract:To solve the problem that random exponential marking (REM) suffered from some drawbacks such as big queue oscillations, sluggish response to dynamic network traffic and poor adaptability to various network conditions, the control property of REM was analyzed, and a dynamic REM (DREM) scheme was proposed. Control theory based analysis indicated that REM had the same property with proportional integral control. Additionally, two new variables, the queue factor and load factor, were introduced to divide the regulating procedure of queue length into four cases, which could identify the network status effectively. Moreover, the key parameter of REM was adjusted dynamically by using the queue factor and load factor to assist the ‘additive increase multiplicative decrease (AIMD)’ strategy-based TCP congestion control mechanism, and enhance the control performance of REM. Simulation and comparison with original REM in NS2 platform demonstrated that DREM could enhance the responsiveness of queue length, reduce the packet loss ratio, and improve the adaptability and robustness for active queue management.关键词：congestion control;active queue management;random exponential marking;queue factor;load factor
- 2954
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- 192
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- 0
发布时间：2023-11-28 - 摘要：Abstract:When the conventional time frequency methods are applied to process multi component radar emitter signals, they have many cross terms, and cannot detect time domain parameters of each signal component and difficultly process signals in low signal to noise ratio. Aiming at these problems, a multi component radar emitter signal detection method based on S method (SM) was proposed. First, the SM time frequency distribution of signals was computed. Then, the instantaneous frequency and time of arrival and termination of each signal component was detected based on SM. Experimental results showed that the introduced approach can process linear and nonlinear frequency modulation signals, and has high time frequency resolution without disturbance of cross terms. The detection precisions in time domain and in frequency domain are more than 98.60% and 99.48%, respectively, and the detection ability is also strong in the low signal to noise ratio.关键词：emitter signal;time frequency analysis;multi component;signal detection;S-method
- 3009
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- 490
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- 1
发布时间：2023-11-28 - 摘要：Abstract:In order to solve the problem of how to share buffer resources for several simultaneous ongoing multicast groups,based on the fact that active router in active network can perform customized computation and provide sotf-stage storage, a novel buffer management scheme, called Adaptive and Active Cache Pool (AACP), for large-scale multicast network was proposed. AACP consisted of three adaptive policies—Global Dynamic Buffer Partitioning Policy, Borrow-In Policy and Return Policy. Global EWMA allocation algorithm and multi-level TTL buffer replacement algorithm were also proposed. Simulation results showed that AACP outperformed other existing reliable multicast protocol in reducing recovery latency and bandwidth consumption, and rasing network throughput. It also meant that AACP could provide high quality supporting foundation for completeness-sensitive and time-sensitive multicast application, such as e-trade system and whiteboard etc.关键词：reliable multicast;AACP;active network;buffer management;buffer partitioning
- 3126
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- 112
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- 0
发布时间：2023-11-28 - 摘要：Abstract:Quasi Orthogonal Space Time Block Codes(QOSTBCs) made space time sequences transmiting with full rate, however, this encodeing method losed partly diversity performance for lowering the orthogonality between antennas. In order to solve to this problem,a transmiting antenna selection scheme for QOSTBCs was proposed. The method was based on R QO STBC, by adaptively mapping the space time sequences of the QO STBC to the appropriate transmiting antennas depending on the channel condition.The proposed scheme could improve its transmiting diversity with limited feedback information. The performance of the scheme with various numbers of antennas selection patterns was also analyzed. The bit error probability of the schemes was evaluated by simulations. It was demonstrated that with the linear zero forcing (ZF) and the minimum mean squared error (MMSE) receivers, the closed loop QO STBC using two feedback bits can achieve almost the same performance as the ideal 4 path diversity and it is about 4~5 dB better than the open loop schemes.关键词：QO-STBC;diversity;EO-STBC;antenna selection
- 2993
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- 490
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- 0
发布时间：2023-11-28 - 摘要：Abstract:Phase unwrapping is the key step of InSAR (Interferometric Synthetic Aperture Radar) imaging,and how to process phase singularity points (SPs) effectively is very difficult problem in phase unwrapping. To remove singularity points effectively, an unwrapping algorithm based on SPs degradation was proposed. Firstly, SPs in interference pattern were detected .Then, these SPs were compensated using neighborhood pixels,and finally the four directions least-square algorithm was employed for phase unwrapping to achieve global optimum.Experiments showed that the new method is effective to remove SPs in high-density SPs interference pattern.关键词：InSAR imaging;phase unwrapping;singularity points;four directions least-square algorithm
- 3551
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- 100
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- 1
发布时间：2023-11-28 - 摘要：Abstract:To overcome the degradation of the transient performance of switching DC DC converters, which was caused by the loop delay in the digital controller, the presence of time delay and its effect on the transient performance was studied, and then the improvement skills were discussed. By the introduction of digital algorithm and sequential diagram, the presence of the loop delay was shown. Based on the digltal peak voltage control, the method to compare the rest time in the present switching period and the duty ratio related time was proposed. By analysis, it showed that it was possible to output the duty ratio and it led to the decrease of the loop delay. On the same application platform, the simulation and experiments were carried out to show the improvement of the transient performance. The results showed that the proposed method was simple, and can improve the transient performance in certain degree.关键词：digital control;switching converter;time delay;transient performance
- 2629
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- 502
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- 1
发布时间：2023-11-28 - 摘要：Abstract:Based on an integration of the conceptual design process from engineering design and the creative process from cognitive psychology, a cognitive process model of conceptual design for product innovation is constructed. The key cognitive activities, information transfer, information operation and mental iteration loops of the model are analyzed. According to this model, a new creative design process for enhancing designer’s creativity is proposed and a support system was developed. Finally, an instance is given to prove the practicability and validity of them.
- 2749
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- 246
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- 6
发布时间：2023-11-28 - 摘要：Abstract:In order to check the detection ability of chaotic oscillator system thoroughly, improve the detection performance and realize the detection of phase randomly distributed weak sinusoidal signal, the detection performance was studied by Monte- Carlo simulation,and the autocorrelation joint with chaotic oscillator detection method was proposed.The autocorrelation was performed to the received signal in order to lose the phase information and suppress a portion of noise, and the result of the autocorrelation was changed into the sine signal whose SNR was improved and initial phase was 0,then the detection was realized by using one equation. The equation group method was avoided, not only the complexity of detection was lowered, but also the detection performance was improved. Monte-Carlo simulation proved that the weak signal detection capability was improved by using the union detection system.关键词：autocorrelation;chaotic oscillator;the detection of sinusoidal signal
- 2546
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- 116
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- 0
发布时间：2023-11-28 - 摘要：Abstract:The high-speed angular cantact ball bearing under load at three direction is used widespread in industry, and the analysis of it’s dynamic character is the base of bearing design and research of spool system. Based on the analysis of conventional calculation method about the dynamic character of high-speed angular cantact ball bearing , a new calculation method is put forward which simplifies the rolling ball under load at 3 direction into two hinge short bar according to the change features of the contact angle under high speed and the deformation of rolling ball and raceway. The specific form of stiffness matrix is given and the solving process by setting initial value of the load at three direction is discussesd. The complexity because of the variable coupling in the conventional Newton-Raphson method is avoid , and the congervence property is improved by this method. An example indicates that the method in this paper is feasible, and can replace the conventional quasi statics method.
- 3096
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- 288
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- 3
发布时间：2023-11-28 - 摘要：Abstract:An online multiple-model modeling method based on spatial partition tree and lazy learning is suggested for complex nonlinear system. The new method establishes the optimum local model of the system based on lazy learning algorithm, which is on the basis of divide-and-conquer principle and input-output data. As working points changing, multiple local models were built to realize the exact modeling for the global system. To select local neighborhoods of the query points, a hierarchical searching strategy based on spatial partition tree is present, and as a result, the real-time performance of the modeling is improved. Simulation results showed the effectiveness of the proposed method.关键词：lazy learning;nonlinear system;online multiple-model modeling;spatial partition tree;k vector nearest neighbors
- 2787
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- 96
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- 3
发布时间：2023-11-28 - 摘要：Abstract:In order to improve the probability of spectrum detection for Cognitive Radio (CR) and utilize the idle spectrum efficiently, a CR system based on cooperative detection and basic function modulation was proposed. Through the cooperation and adopting the energy detection with auto-adapted threshold, the CR system obtained the spectrum estimation and generated the sub-basis functions which were orthogonal with primary users'signals. The sub-basis functions were connected to be the system's basis function by convolution, and the system implemented receiving and transmitting through modulating the data on the system's basis function. Simulation showed that the system could improve the detection probability and debase the Bit Error Rate (BER). Its anti-interference and utilization of the idle spectrum were predominant.关键词：cognitive radio;cooperative detection;energy detection;auto-adapted threshold;basis function
- 2768
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- 120
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- 0
发布时间：2023-11-28 - 摘要：Abstract:A concept “Straight-Arm Capture” and a method of configuration planning are proposed, which are based on the momentum conservation of space manipulator. The configuration by using the proposed method can reduce the coupling momentum、joint angular velocity and the burden of compound control, then avoids the limit of joint velocity and torque when control the compound. Finally the simulation results show that the effectiveness of the method.关键词：space manipulator;configuration planning;impact;coupling angular momentum
- 3789
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- 690
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- 4
发布时间：2023-11-28 - 摘要：Abstract:In order to get the characteristic parameter of gas-solution interface in magnetic field， measurement of deformation was done by the method based on mirror image combined with the structure illumination. The quantitative results of surface deformation were calculated from the phase unwrapping of gray matric and 3D reconstruction. The present experiment demonstrated that the unhomogeneity of surface tension induced by gradient magnetic field near the surface of liquid could lead to surface deformation, the quantity and direction of deformation are directly related to the distribution of gradient filed, and a new way to the research of the kinetics of Buoyant-Thermcapillary Convection is proposed.关键词：gradient magnetic field;surface deformation of liquid;structure illumination;mirror image;gray matric;phase unwraping
- 2166
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- 82
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- 0
发布时间：2023-11-28 - 摘要：Abstract:A new approach of calculating the capacity power price of two system power transmission pricing based on complex power flow tracing was proposed. Firstly, the capacity cost of lines was computed by average increment cost method. Then the model of lossless system by adding virtual node of lines to regarding the loss as a virtual consumer was established, and the capacity cost corresponding the loss based on the MW-Mile method was calculated. The‘using degree’of lines for the consumers including the virtual ones were calculated by complex power flow tracing method, so the capacity cost and the loss of lines after lossless management were apportioned. At last, the capacity power price of real consumers were figured out accorrding to the market principle. Results of a numerical example showed that the method has a preferable ability in capacity cost reclaiming and calculation precision, and could satisfy the impartiality principle in power market. Meanwhile, it was verified that the proposed method is rational and feasible.
- 2903
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- 104
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- 0
发布时间：2023-11-28 - 摘要：Abstract:An self-adaptive slicing algorithm for scattered points is proposed, which has four steps: first, the slicing neighbor points are obtained based on the spacial index structure of scattered points; second, the slicing neighbor points are divided into two parts; third, the slicing points are obtained by the intersecting between matching points of slicing neighbor data and the slice; fourth, the intersecting points are sorted with algorithm of Minimum Spannirng Tree.This algerithm can obtain slicing points accurately, effectively and has strongly adaptability of data type.
- 2756
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- 96
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- 0
发布时间：2023-11-28 - 摘要：Abstract:To characterize the instabilities of unsteady flow in Kenics Static Mixer (KSM) with 0.04 m in diameter and 1.25 in aspect ratio, the turbulent time series of instantaneous velocity fluctuation were measured by Laser Doppler Particle Analyzer in the turbulent region under the range of Rebetween 3972 and 11916. A method based on wavelet threshold de-noised transform and fractal theory was used to extract the large-scale turbulent signal with multip-scales resolution under different compact support Symlet wavelets. Results showed that the hurst exponents fluctuated between 0.845 and 0.896 which indicated that the instantaneous large-scale velocity fluctuation have persistence and self similarity fractal in lower phase space. The hurst exponents decreased firstly then increased as axial position increased, but increased firstly then decreased as radial position increased which have two peak value for the single mixing-element. Decomposition error was the minimum under Sym 8-order wavelet, and the velocity signal in the element-transition had the strongest singularity.关键词：static mixer;instantaneous velocity;threshold de noise;optimal wavelet;fractal
- 2686
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- 118
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发布时间：2023-11-28 - 摘要：Abstract: In order to obtain the distribution rules of fluctuation pressure of train head surface, body-fitted quadrilateral and hexahedron grid was obtained of high speed train head surface based on parameter space mapping approach. The fluctuation pressure caused by streamlined curved surface of train head was calculated with LES (large eddy simulation), the distribution rules of fluctuation pressure were obtained: the fluctuation pressure is local, namely the fluctuation pressure produced at a certain point mainly affects this point, and the influence on other point weakens promptly when it is apart from this point; The frequency band of fluctuation pressure is very wide, and does not have obvious main frequency. The amplitude of fluctuation pressure is greater at low frequency. With the increase of frequency, amplitude drops continuously according to negative index law. The major energy of 1/3 octave band fluctuation pressure focuses on the frequency scope from 20 Hz to 500 Hz. With the increase of train speed, the major energy of frequency spectra has the tendency that moves to high frequency.关键词：high speed train;train head surface;fluctuation pressure;large eddy simulation
- 2372
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- 94
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发布时间：2023-11-28 - 摘要：Abstract:An algorithm for identification of small target suspicious region in a large background in machine vision inspections was developed, which was based on the simulation of human visual attention mechanism for detecting contaminants in cotton. Firstly, Principal Component Analysis (PCA) and discrete cosine transform (DCT) were adopted to compress the data in the divided image blocks and extract their main features for pattern recognition. Then BP neural networks and Support Vector Machine (SVM) were used to identify suspicous target area respectively. The results indicated that the algorithm can be used for identification of suspicious target region in machine vision inspection, the accuracy of which was mainly determined by the size of the divided image blocks, the algorithms for data compressing and methods for pattern recognition. Finally, based on analysis of the results, further research for improving the algorithm was suggested.关键词：visual attention;machine vision system;small target detection;algorithm
- 3414
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- 128
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发布时间：2023-11-28 - 摘要：Abstract:Elastic deformation of rollers in the process of sheets and strips rolling significantly the quality of profile shape. In order to study this elastic deformation,a mechanical model of contact among rollers and between work roll and rolled piece was constructed on the basis of elastic basis beam theory，and simulated by spring. An analytical mathematical model of the elastic deformation of rollers in 6-h mill was presented. A method which coupled the distribution of section shape of rolled piece and rolling pressure were proposed to iteratively compute the elastic deformation of rollers and the section shape of rolled piece. At last, a finite element model based on the nonlinear contact theory of elastic deformation of rollers was formulated using the software of MSC.MENTAT/MARC. The computed results showed that the section shape of rolled piece and the crown of strip calculated using the analytical method and the finite element model are similar to that of the field measurement, which effectively verifies the proposed research methods and the formulated model.关键词：elastic basis beam;rollers;6-h mill;nonlinear contact finite element
- 2805
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发布时间：2023-11-28 - 摘要：Abstract:In order to overcome the disadvantage of overflow energy loss in conventional injection molding machine, an accumulator module installed in hydraulic injection molding machine was self-designed to save the work energy of the machine. The energy consumption data of injection molding machine with accumulator module and without accumulator module were measured and compared throughmany tests. It was found that the energy consumption of injection molding machine with accumulator module is decreased significantly. The primary investigation and discussion about the energy conservation data of the accumulator module was presented. The different energy saving effect of accumulator module on the condition of different back pressures, different dwell times and different moulds was analyzed on the basis of the energy saving mechanism of the accumulator module.关键词：accumulator;energy saving;energy consumption;hydraulic injection molding machine
- 2834
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- 102
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发布时间：2023-11-28
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