最新刊期
卷 38 ， 期 6 ， 2006
- 摘要：Abstract:A series of concludes have been obtained，through theoretical analysis, formulas derivation and parameters calculation based on analysis of the motion mechanism of non-uniform bed load. The minimum dimensionless critical shear stress value of non-uniform sediment has been obtained as 0.020. The formula for calculating the transport rate of bed load of non-uniform sediment has been proposed. The formula shows the transport rate is not a constant but varies with the relative exposure degree of particles that lying on riverbed when the flow intensity is at fixed value. The condition and formula for calculating the maximum diameter, dc max, of incipient sediment according to the minimum dimensionless critical shear stress value, θ0, of bed load at equilibrium condition has been put forward. And a formula for calculating the size distribution of bed load has been presented too. Results above mentioned have been verified with field or laboratory experimental data.关键词：river dynamics;bed load;exposure degree;bed load discharge;size distribution
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发布时间：2023-11-28 - 摘要：Abstract:The key points of ceramsite Concrete composite slabs without middle brace in construction are bearing capacities of trough bottom plates and shear strength of trough contact plane, which are important design parameters. To study bearing capacities of trough bottom plates and composite slabs and evaluate the shear strength of trough contact plane, three bottom plates and three composite slabs are tested and load bearing capacities, crack resistance, elastic restoring capacities of bottom plates and composite slabs are analyzed. The test results and theoretical analysis show that the trough bottom plates and composite slabs have higher resistance to bending, crack resistance and elastic restoring capacities, and application of ceramsite concrete reduces dead load and ensure the feasibility of the trough bottom without brace in construction, in addition trough contact plane has higher shear strength than that of rectangle contact planes. Finally, the application of composite slabs without brace in steel construction has shorter period of construction and better economic indicator compared with cast in place concrete slab.关键词：ceramiste concrete;trough bottom plate;contact plane;no brace;crack resistance
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发布时间：2023-11-28 - 摘要：Abstract:To study the interface slip and the deflection properties of a new type of steel-encased concrete composite beams, four full size simply supported specimens with different shear connection coefficient were designed. One was a beam with full shear connection, and the others with partial shear connection. According to the experiment , a set of load-slip curves and load-deflection curves are derived. Based on these results, the interface slip development process and distribution laws are gained. Taking the interface slip into account, a nonlinear finite element analysis model is established by using the finite element analysis soft-ANSYS, and gains a reasonable shearing connection coefficient. Based on the actual code, a theoretical formula is proposed for deflection. The results of finite element model and theoretical formula are proved to be in good agreement with the experimental data.关键词：steel-encased concrete composite beam;interface slip;deflection;nonlinear finite element analysis;theoretical formula
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发布时间：2023-11-28 - 摘要：Abstract:In order to develop up-wind scheme for convection-diffusion equation under high Reynolds number, exponent or power function was used as power coefficient of auto up-wind. The power coefficient of corner point was computed and skew up-wind property was kept by coordinate system circumgyrating and transform. Moreover, the complete nine-point scheme for 2D convection-diffusion equation was developed. The scheme can be used to curvilinear coordinate grid. It was indicated that the scheme will not changed to simple up wind as Reynolds number increas.关键词：convection and diffusion;auto up-wind;skew up-wind;high Reynolds number
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发布时间：2023-11-28 - 摘要：Abstract:The main idea, features and key points of support vector machine (SVM) have been introduced in this paper. Then prediction of runoff has been studied with SVM technique, and compared with traditional threshold regression model (TR) based on genetic algorithm. The results of case studies have shown that the SVM method is functional and feasible.关键词：Support Vector Machine (SVM);Structure Risk Minimization (SRM);prediction of runoff
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发布时间：2023-11-28 - 摘要：Abstract:A projection pursuit dynamic cluster (PPDC) model is proposed, which combines projection pursuit principle with dynamic cluster rule. Firstly, multifactor cluster problem is converted into single-factor cluster problem according to linear projection technique. Secondly, a new projection index based on dynamic cluster rule is constructed in the PPDC model, which would finish the sample clustering based on the projected characteristic value. In comparison with the existing projection pursuit cluster (PPC) model, we construct a new projection index based on dynamic cluster method in the PPDC model, which successfully avoids the problem of parameter calibration in the PPC model and makes the cluster results more objective. On the other hand, the cluster results can be outputted directly according to the PPDC model, but in the PPC model the cluster results can be got using other method to re-analyze projected characteristic values. A case study of groundwater classification is given at last, and the results show that the PPDC model is reasonable and easy to operate in practice. The PPDC model is a new method for multifactor cluster analysis and has a bright future in cluster analysis field.关键词：projection pursuit;dynamic cluster;linear projection;projection index
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发布时间：2023-11-28 - 摘要：Abstract:In order to evaluate the reliability and validity of hydrologic forecast model, Set Pair Analysis(SPA) method was introduced to describe the error distribution of hydrologic forecast model from identical, discrepancy and contrary and to measure the precision by correlation degree. Therefore the evaluation method of hydrologic forecast model based on SPA was built. Through comparison of correlation degree between TR model and linear model and evaluation of simulation and forecast data, the results showed the TR model is better than the linear model. Compared with other evaluation methods, the SPA possesses the characteristic of comprehensive information, simple computation and easy practical usage.关键词：SPA;correlation degree;hydrologic forecast model;evaluation
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发布时间：2023-11-28 - 摘要：Abstract:This paper deals with the water surface superelevation in sharp open-channel bends. The regime of rapid flow in sharp open-channel bends is described, which shows that the flow near concave bank in sharp open-channel bends is subjected to centrifugal force and impact force. Based on this regime and momentum equation of the flow, the formula for calculating the surface superelevation of rapid flow in sharp open channel bends is derived. The reasonability of the theory is verified with experimental data. On basis of the formula, the relutionship between surface superelevation and relevant factors is discussed. The results show that the water surface superelevation is approximately linear with channel width and is closely related to bend angle and radius.关键词：hydraulics;rapid flow;water surface superelevation;sharp open-channel bends
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发布时间：2023-11-28 - 摘要：Abstract:By the analysis of the field data of gravel bedload rate, it is found that the gravel bedload rate has a distinct stochastic nature and turbulence intensity of bedload rate is closely related to the sampling duration. The deviation, diversity coefficient，dimensionless turbulence intensity and dimensionless ultimate difference of bedload rate per unit width, all decrease with the increase of sampling duration. The maximum value of dimensionless ultimate difference of bedload rate per unit width is about 8.0. As the sampling duration t≥600 s, the dimensionless ultimate difference Z≤4.0. As the sampling duration t≥2400 s, the dimensionless ultimate difference Z≤2.0. The deviation coefficient of bedload rate per unit width has a maximum value of 2.0. As the sampling duration t≥1200 s, the deviation coefficient Cv≤1.0. As the sampling duration t≥3000 s, the deviation coefficient Cv≤0.5. The dimensionless turbulence intensity of bedload rate per unit width has a maximum value of 10.0. As the sampling duration t≥1200 s, the dimensionless turbulence intensity E′≤5.0. As the sampling duration t≥3600 s, the dimensionless turbulence intensity E′≤2.0.关键词：fluctuation nature;gravel bedload;sampling duration
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发布时间：2023-11-28 - 摘要：Abstract:A numerical method is established to describe the distribution of pressure and temperature in the natural gas wellbone with downhole choke from wellhead to bottom. The Mach number in the outlet of the choke is calculated and used to discriminate the flow state. Then, according to the value of the Mach number, parameters in throat and inlet of the choke are also calculated. At last,based on the preceding numeration, pressure and temperature of upstream can be solved. The computed results of Bao No.1 wellbone show that values of pressure and temperature rapid drawdown in the outlet of the downhole choke, and then quickly rising after the section of shock wave.关键词：natural gas;downhole choke;critical state;Mach number;shock wave
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发布时间：2023-11-28 - 摘要：Abstract:In electric power market, the bidding strategy of power producer has very great influence on its profit and power producer should study the bidding strategy in order to maximize its own profit. The bidding strategies among power producers in electric power market were studied with non-cooperative game theory under inelastic electric power demands. According to the characteristics of the problem，based on PSO, the multi objective programming model of the solution of Nash equilibrium was given， and the approximate result was obtained. The result can guide the power producers to constitute the bidding curves， which makes the producers not be blind to bid.关键词：bidding strategies;game theory;Nash equilibrium;PSO
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发布时间：2023-11-28 - 摘要：Abstract:A new analytical method with sum function is introduced for solving plane problems of elasticity. The stress analysis of simply supported deep beam subjected to triangular distributed load has been performed. Furthermore, the Fourier series solution about above problems was given for the studied problem. The present method not only translates the coupling partial differential equations of elasticity into a few independent partial differential equation each other, but also the results using the present approach possess the same solution with those of traditional Airy stress function method. The correction and practical values was confirmed. The present method provides a more space of classical analytical method for solving the practical engineering problems.关键词：elasticity;sum function method;simple supported deep beam;series solution
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发布时间：2023-11-28 - 摘要：Abstract:The porous hydroxyapatite (HAP) used as suspension polymerization dispersant was prepared using calcium carbonate and phosphoric acid as starting materials. The samples were characterized by SEM，XRD and BET Nitrogen Adsorption Instrument. The results showed that the prepared HAP has porous structure, low apparent density, large specific surface area, uniform particle size and is not agglomerate between the particles. The optimal preparation conditions for the HAP were determined as follows：solid content of calcium carbonate aqueous suspension 90 g/L, concentration of phosphor 1.0 mol/L, reaction/aging temperature 50 ℃, aging time 3h. The HAP prepared at optimal preparation conditions has a specific surface area of 106.8 m2/g,1.5~1.8 times that of Japanese HAP and selling HAP. The results of the application in the suspension polymerization of styrene showed that the porous HAP dispersant has high surface activity, excellent suspension dispersibility and stability and can markedly improve the quality of polystyrene beads.关键词：hydroxyapatite;porous structure;inorganic dispersant;suspension polymerization
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发布时间：2023-11-28 - 摘要：Abstract:The flocculation experiment using PAC was carried out to study the impact of the physico-chemical condition of micro-organic-polluted water and hydraulic condition on fractal dimension of aggregated floc by scanning the electron microscope photos. The results showed that the fractal dimension increases from 5.13% lower than the standard to higher 16.03% when residence time from 20.00% shorter than the reference time to longer 33.30%, the fractal dimension is the biggest when the coagulant dosage is optimal, and the fractal dimension of aggregated floc decreases by 17.06% ~31.5% and increases to 24.39%~28.13% when the coagulant dosage is short and excessive separately. The results showed that the fractal dimension has good response to the flocculation factor, and it can be used as a parameter of quantitative analysis of flocculation efficiency.关键词：flocculation;fractal dimension;micro organic-polluted-water
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发布时间：2023-11-28 - 摘要：Abstract:Phenol degradation by heterogeneous Fenton-like reaction under microwave field was investigated. The experiments of phenol degradation under microwave field and normal condition were conducted, and the reaction kinetic curves were determined. The effects of reaction temperature and microwave power on the removal rate of phenol and TOC were discussed. The reaction activation energies required for phenol degradation were estimated. Results showed that application of microwave radiation can improve the degradation rate and the removal rate of phenol as well as the removal rate of TOC in the heterogeneous Fenton-like reaction. Overall kinetics of the phenol degradation was nearly third order. The reaction activation energies under the microwave field were lower than that without microwave irradiation. When the microwave power were 200 and 600 W respectively, the corresponding reaction activation energies under the microwave field were 17.175 and 15.042 kJ/mol, respectively which decreased 11.48% and 22.48% in comparison with that when no microwave was used.关键词：microwave;heterogeneous Fenton-like reaction;phenol;TOC;degradation
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发布时间：2023-11-28 - 摘要：Abstract:Polypropylene grafted multi-wall carbon nanotubes (PP-g-MWNT) were prepared through radical reactions in the PP/MWNT suspension irradiated with ultraviolet (UV) for 24 h in the presence of initiator. The existence of PP-g-MWNT structure was confirmed and characterized by means of transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), Wide angle X-ray diffraction (WAXD), Thermo gravimetric analysis (TGA). The results showed that PP chains wrapped onto the MWNT of shorter length. The absorptions and diffractions of PP characteristics were found on the FTIR spectrum and WAXD profiles of the PP-g-MWNT, which were indicative of the occurrence of graft reaction. WAXD results also suggested that the grafted PP has different crystal structure from that of the PP control. TGA results showed that the degree of grafting PP onto MWNT was about 10.4wt%. No significant changes were found in the D line and G line of the Raman spectra of the PP-g-MWNT, suggesting that MWNT structure remained unchanged after the grafting reactions.关键词：multi-wall carbon nanotubes;polypropylene;grafting reaction;ultraviolet irradiation
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发布时间：2023-11-28 - 摘要：Abstract:With the calcium polyphosphate(CPP) as a control, the microstructure, degradation in vitro and the cytocomptibility to vascular endothelial cells(VECs) of strontium-doped calcium polyphosphate(SCPP) were investigated, and the effects of strontium on the structure and properties of CPP scaffold were discussed. The crystalline grain of SCPP were enlarged, which linked together more tightly and developed a smoother surface. Moreover, the degradation rate of SCPP was slower. In the degradation fluid of SCPP, strontium was detected, the concentration of which increased with time. The cytocompatibility of SCPP was promoted apparently. The VECs on the SCPP scaffold attached more quickly and fully spreaded, developing a monolayer endothelium and wrapping the surface of scaffold. After cultured with the degradation fluid of SCPP, cell proliferation ability was up-regulated significantly(p<0.05). As the multiple stepwise regression results demonstrated, the main reason for proliferation increase is the strontium ions in the degradation fluid(R2=0.670, p<0.01).The results showed that, SCPP is more compatible with VECs, which is essential in angiogenesis, and may serve as a more promising scaffold for bone tissue engineering.关键词：Strontium-doped calcium polyphosphate;vascular endothelial cells;cytocompatibility
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发布时间：2023-11-28 - 摘要：Abstract:The present authentication scheme has been found to be vulnerable to forged login attack; an intruder could still impersonate legitimate users to login and accesses the remote server in two ways at least. To solve this problem, an improved scheme will be proposed, which can withstand the existing forged attacks by means of improving the security policy and authentication information. The security analysis showed that the improved scheme still keeps the features of the non storage data model authentication scheme and will not add the additional computation cost to the smart card, and will perform better in security and practical operations.关键词：authentication;security improvement;personate attack;smart card
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发布时间：2023-11-28 - 摘要：Abstract:Function mining algorithm based on traditional Gene Expression Programming (GEP) and other improved algorithm may still lead to local optimum trap. To solve this problem, a new algorithm based on Genome Diversity Guided (DG GEP) in grading evolution was proposed. The definition of GEP evolution phase and genome diversity evaluation model were given. The concept of anagenesis factor to describe evolution phases and strategy of grading evolution were proposed. The means of dynamic genetic operators and population control were used to make the evolution escape from localization trap quickly. The experiment showed that the new algorithm decreases the generations-stagnancy over 65% and increases the average fitness of colony over 12％.关键词：Gene Expression Programming(GEP);grading evolution strategy;diversity evaluation;dynamic genetic operators
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发布时间：2023-11-28 - 摘要：Abstract:With the evolution of civil and military simulation and C&C system, in many cases we need to real-timely render terrains with huge texture which is too large to fit into video memory. We present a new virtual huge texture management technique to resolve the problem. This algorithm is based multi-resolution representation of texture and view point dependent cache and paging strategy. During the paging process, we fully make use of hardware’s texture transform ability to save bandwidth consumption, another advantage of this algorithm is that, the user can use this virtual texture as an ordinary texture OpenGL texture, the paging operation is totally transparent. The dimension of texture is only restricted by hard storage capacity and floating point bit depth, while the efficiency is comparable to small size hardware texturing.关键词：virtual texture;terrain visualization;texture cache
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发布时间：2023-11-28 - 摘要：Abstract:The distributed fusion algorithm was applied to process the fusion tracks from local ATC center, and solve the problem of the poor quality of the track on the fusion edge. Some key problems in the distributed fusion algorithm, such as error registration, tracks correlation, and tracks fusion were discussed. The proposed methods were proved to have significant improvement effects.关键词：Air Traffic Control(ATC);stributed fusion algorithm;time-space registration;credit;track correlation
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发布时间：2023-11-28 - 摘要：Abstract:In the light of the deficiencies of current grid trust models based on PKI (Public Key Infrastructure), such as ambiguity certificate information and complicated identification process,a novel grid trust model based on Family Gene (FG) model was proposed. The model solves the problems existing in tradition trust models. For example, we adopt the technology of the whole sequences of information required by a user to address the ambiguity certificate information, gene identification to solve the complexity of authentication process, and gene assignment to address the complexity of visit and control. The concepts and formal definitions of grid family, family gene, gene assignment, gene identification and trust in the grid trust security domains were given. Then, the mathematical models were established. The theoretical analysis and experimental results showed that the model is a good solution to grid trust domain.关键词：family gene;grid family;trust;gene authentication;gene assignment
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发布时间：2023-11-28 - 摘要：Abstract:For solving effectively premature convergence and genetic drift that often occur in applying Gas to practice, the reason for the premature and genetic drift was analyzed. A new aproach based on fuzzy cluster was proposed to effectively overcome the two phenomenon. The covergence of the new algorithm was discussed. Experimental results showed that the new algorithm is more effective than classical genetic algorithms.关键词：genetic algorithms;premature convergence;genetic drift;fuzzy cluster
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发布时间：2023-11-28 - 摘要：Abstract:The elastohydrodynamic lubrication theory was used to study the elastohydrodynamic lubrication problem of swing movable teeth transmission. A set of equations for elastohydrodynamic lubrication of swing movable teeth transmission were established. A numerical method for solving the elastohydrodynamic lubrication problem of the transmission was put forward. The results showed that the calculation formula and the numerical calculation method of the elastohydrodynamic lubrication of swing movable teeth drive are correct and effective; the lubrication oil film thickness increases with the decrease of the load，with the increase of the synthetic curvature radius and entrainment velocities; the change law of the oil film thickness between a movable tooth and the internal gear is that the oil film thins gradually during the former half of a mesh period and thickens gradually during the latter half of a mesh period,the oil film is thinnest near point of inflection.Near the point of inflection, fatigue pitting or wear occurs easily.The research results can be used as a theoretical basis for the tribology design of swing movable teeth drive.关键词：swing movable teeth transmission;elastohydrodynamic lubrication;numerical method
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发布时间：2023-11-28 - 摘要：Abstract:In order to enhance design accuracy and performance，three dimensional viscous flow inside axial flow runner is simulated based on time averaged Navier-Stokes equations, standard k-ε turbulence model, and SIMPLEC algorithm. Predicted efficiency of axial flow runner is obtained according to computational approach of hydraulic loss. distribution pattern of flow fields in axial flow runner obtained by the simulation can be used to understand true flow phenomena and improve design, and established pressure variation curve in wrapping angle of blade.关键词：axial flow runner;three dimensional turbulent flow;numerical computation
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发布时间：2023-11-28 - 摘要：Abstract:The microvibration response analysis of precision optical equipment support structure is the guarantee of the large optical system working steadily. To analyze whether the response can satisfy the design demand, this paper measure the ground ambient vibration of the precision optical device support structure by the way which is used to measure background sound by removal digital seismograph, analyze the data and discuss how to do support structure microvibration response analysis by the measure data. The spectrum analyse module of ANSYS is used to analyze the mirror mount’s response. The results indicate that the mirror mount under the effect of micro vibration can satisfy design demand.关键词：digital seismograph;microvibration;precision optical support
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发布时间：2023-11-28 - 摘要：Abstract:A continuous ohmic heating system with vertical compartments for liquor was designed. The soybean milk ( with the solid content of 6.01% and (75 ± 0.5) kg/h the mass flow rate) was heated with the system. The results showed that the temperatures of tap water and soybean milk increase evenly within each ohmic heating compartment from the bottom to the top. The heating process is stable . The electrical conductivity of the soybean milk during continuous ohmic heating increases linearly with its temperature. However, the value of the electrical conductivity measured with the continuous ohmic heater is lower than that measured with the batch ohmic heater at the same temperature during ohmic heating. The reason is that the fouling occurred on the surface of the electrode in the continuous ohmic heater.关键词：vertical compartment mode;ohmic heating;continuous flow;electrical conductivity
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发布时间：2023-11-28
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