最新刊期
卷 39 ， 期 1 ， 2007
- 摘要：Abstract:The flood releasing energy dissipation facility and scouring depth of a RCC double curvature arch dam with 98m in max height and a 3 surface bay spillway is experimentally studied. The scale of the hydraulic model is 1∶60. The ski jump spillway and a new type dissipater are adopted to bring about energy dissipation by impact of low and high sill flows and impact of lateral diffusion. In addition, by increasing the falling area as large as possible and making full use of the down stream water depth, the scouring depth is reduced from the original 30 m to less than 18 m, then the problem of scouring and energy dissipation is solved. The arrangement and dissipater proposed in the model test can also provide reference for similar projects.关键词：double curvature arch dam;model test;ski jump spillway;Energy dissipation;depth of scour
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发布时间：2023-11-28 - 摘要：Abstract:With a numerical model for unsteady sediment transport during flood routing, work is done to hindcast the flood routing through the lower Yellow River during the flood season in 1997、the real time flood routing during the flood season in 1998,the process of flow and sediment transport during the flow and sediment regulation in 2002 and a phenomenon of the abnormal flood peak increment during the process of 04.8” flood. Comparison of the calculated and measured values shows the model can precisely simulate the processes of flow and sediment transport, flow level variation, erosion and deposition. In addition, the model can predict the abnormal phenomena in the course of flood routing. The precision of calculated results is found good enough to satisfy the need for flood control in flood seasons.关键词：the lower Yellow River;prediction;flood routing;flood level
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发布时间：2023-11-28 - 摘要：Abstract:The flow field characteristics of vertical vortex with multi circle spiral flow at hydraulic intakes are described by numerical simulation, experimental investigation, and theoretical equations. VOF method is used to deal with the free water surface in the numerical simulation. The coloring tracer is employed as tracker particles in the test. The theoretical equations for 3-D velocities add the change of vertical vortex in the axial direction, which on other model does. The velocity distribution of the numerical simulation and the theoretical equations calculation are compared on the condition of axial symmetry. It shows that flow field of vertical vortex is not only the function of the radial coordinate but also the function of the axial coordinate. Taking the advantage of numerical simulation that can simulate the different types of boundary conditions, the vertical vortex induced by the asymmetric initial flow is simulated too.关键词：vertical vortex;multi-circle spiral flow;the flow field characteristics
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发布时间：2023-11-28 - 摘要：Abstract:A nonlinear perturbation model (NLPM) based on Artificial Neural Network (ANN) and considering the antecedent precipitation index (API) is proposed and developed. The model structure is similar to the NLPM-API model. The difference is that the ANN is adopted to simulate the relationship between the input perturbing terms and the output perturbing terms. The daily rainfall-runoff data from the Mumahe and Nianyushan reservoir basins is selected to test the model. The proposed model is compared with the LPM, NLPM-AMN and NLPM-API models, the model efficiencies in these two basins are increased 10.84%, 1.54%, 10.6% and 21.59%, 0.67%,10.11% during calibration period; 5.56%, 0.97%, 4.41% and 11.86%, 1.76%, 7.97% during verification period, respectively. All other assessment indexes are also superior to other models.关键词：flood forecasting;linear perturbation model;artificial neural network;antecedent precipitation index;NLPM-AMN model
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发布时间：2023-11-28 - 摘要：Abstract:Water temperature in reservoirs is a very important water quality factor which effects the living of aquatic biology system. In order to predict the thermally stratified law and the flow characteristic, a new three dimensional turbulence model, named shear stress transport turbulence model, was described in detail. Comparisons between field data and the computed data of the laterally averaged hydrodynamics model were presented. It shows the mathematical model can be used to predict the features of the thermally stratified flow in reservoirs, and can give more details of the submergence flow of different density.关键词：reservoir;thermally stratified flow;shear stress transport(SST);numerical simulation
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发布时间：2023-11-28 - 摘要：Abstract:In order to study on the problems of cracking similarity conditions and test simulating method of induced joint in structural model test, fracture property tests of material and mechanics theory deducing are presented in this paper. According to the similarity criterion of structural model test, prototype material and model material need to conform to the similarity conditions of fracture property and shear friction strength. The fracture toughness of RCC, considering the size effect, and the curve of water-gypsum ratio vs. fracture toughness of gypsum are obtained by material fracture tests. Furthermore, theory of fracture mechanics is used to analyze the relation between fracture toughness and stress intensity factor, the similarity conditions of cracking property is deduced, and the model sizes of induced joint, conformed to the cracking conditions, is calculated. In the test, a copper sheet cover with mylar is used as the joint material and the shear-friction strength similarity condition is satisfied by considering the comprehensive effects of f and c. Consequently, cracking similarity simulation of induced joint is realized in structural model test. The results provide the basis for researching cracking and failure mechanism of RCC arch dam with induced joints.关键词：structural model failure test;induced joint;cracking property;cracking similarity simulation
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发布时间：2023-11-28 - 摘要：Abstract:Based on triangular grids, the planar 2-D flow and sediment mathematical model in natural branching river has been established by using the finite element method. Since the mass concentration and pre-estimated and verified iteration are used to solve the equations, the question of memory units and calculation velocity are settled quite well. Simulation calculation carried out on Tianxingzhou reach of the Yangtze River shows the result is closely fitted with the field data, which showes that the model is creditable, it can provide the technical support for research on the natural branching river regulation.关键词：branching river;finite element method;2-D flow and sediment mathematical model
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发布时间：2023-11-28 - 摘要：Abstract:This paper presented the law of resistance transverse distribution in braided river，which is one of the key factors to study on the evolution rule of braided river. On the base of analyzing the characteristic of braided river, it is found that resistance transverse distribution is closely related to the great change discharge flood, different situation of riverbed composed by sand of small grain diameter and the landform change. According to the observed data from braided reach of Yellow River, the formula of resistance transverse distribution in braided river had been established after the relation and the law between above-mentioned three factors and resistance in the river has been confirmed. Compared with the observed data and the computed value, it is shown that the formula can represent the law of resistance transverse distribution in braided river.关键词：braided river;resistance;transverse distribution
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发布时间：2023-11-28 - 摘要：Abstract:The critical height of bedding rock slope is investigated using the kinematic approach of limit analysis. Firstly, linear equations are introduced to express the shear strength of layered rocks, which is treated as a transverse isotropy material. Then, one case of bedding rock slope is investigated and calculation procedure is developed. Finally, a practical slope was calculated using the method proposed. It is found that when the inclination angle of the layered rocks is between 48° and 70°, the slope will fail along the layer. It is concluded that the proposed method can be used as guidance for slope excavation.关键词：bedding rock slopes;critical height;limit analysis;transverse isotropy
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发布时间：2023-11-28 - 摘要：Abstract:The pumped storage power station complemented by wind and light energy is a new way of energy development which assembles the respective advantages of the traditional hydropower, wind and light energy. The mathematic model of the energy and water equilibrium and the pumping system capacity were raised according to the unique natural geographic condition in Tibet Ali. The optimum model was set up in which the cost price of electricity and investment per kilowatt is lowest. The research was done on the system configuration of the pumped storage power station complemented by wind and sunlight energy for the example in Ali. Then the best match proportion and the corresponding storage configuration requirement of hydropower, sunlight and wind energy were proposed. The result reveals that the shortage of higher cost price of electricity and demand of operation safeguard could be improved for the way of energy developing which give a further indication of the unique technical and economic advantages. It is a good way to solve the energysupply for the area of Tibet Ali.关键词：complemented energy model;multi-energy(wind, sunlight, water) utilize;system configuration;Tibet Ali
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发布时间：2023-11-28 - 摘要：Abstract:In order to seek an advanced numerical simulation method to study the flow field characteristic of the river current,this article uses the VOF turbulent flow mathematical model to simulation study of fluvial channel velocity field of river stretch both before and after the Anshunchang embankment be constructed. The change situation of velocity of flow, the direction, the water level and so on are compared before and after the embankment be constructed. The simulative computation indicates that the VOF turbulent flow mathematical model is an effective method for processing complex free surface.This method not only has good stabilization, strong flexibility and high accuracy precision, but also the grid division is flexible, therefore can simulate the irregular river course boundary well, thus suits to the simulation of natural river velocity field.关键词：three-dimensional;velocity field;VOF method;numerical simulation
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发布时间：2023-11-28 - 摘要：Abstract:The dynamic splitting tests of marble using Brazilian disc and flattened Brazilian disc were performed at high strain rate with split Hopkinson pressure bar (SHPB) of 100 mm diameter. A series of electrical resistance strain gauges were stuck on the samples along the loading diameter in order to record the strain histories, from which the strain, the time and position of the crack initiation, and the consequence and the velocity of the crack propagation could be detected. Experimental results indicated that crack initiation time was in accordance with the sudden change of the strain. Generally speaking, the crack does not initiate from the center of the sample, but from a certain point between the center and the interface where the incident bar impacts the sample. Then the crack propagates in opposite directions along the loading diameter till splitting into two halves. The velocity of the crack growth ranges from 400 m/s to 800 m/s, and the failure time is about dozens of microseconds. With low strain rate loading, the failure pattern of the sample is good and there are fewer turnoffs during the growth of the crack. On the contrary, with high strain rate loading, the failure pattern of the sample is diversified and there are more turnoffs at the fracture path. It is a brief, effective method to stick a series of strain gauges along the loading diameter of the sample to gain the characteristics of the dynamic crack initiation and propagation for brittle materials.关键词：split Hopkinson pressure bar(SHPB);dynamic splitting test;Brazilian disc;dynamic crack initiation;crack propagation;strain history
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发布时间：2023-11-28 - 摘要：Abstract:Micro-mechanism of granular materials is complicated for the discrete behaviour. Numerical method of DEM is applied to the study of micro-structure of binary packing of spherical particles in terms of size and distribution of coordination number under the influence of gravity force. Results show that the volume fraction influences the distributions of coordination number of single contact type and individual components. It features that increasing the volume fraction of small component increases the small-to-small and large-to-small contacts and decreases the small-to-large and large-to-large contacts. The mean coordination number of small and large component both increase with the increase of the volume fraction of small component, and the trend is more apparent for large component. However, the overall mean coordination number is essentially a constant and independent of porosity or volume fraction for the binary packing under gravity.关键词：rigid particles;Discrete Element Method (DEM);coordination number;micro-structure
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发布时间：2023-11-28 - 摘要：Abstract:A new method for the determination of ethanol based on the immobilized enzyme fluorescence capillary analysis (IE-EFCA) was proposed. Alcohol dehydrogenation (ADH) was immobilized in inner surface of a capillary. After NAD+ as an oxidizer was mixed with the samples solution, the determination was conducted to the mixed solution in the capillary at 350 nm of excited wavelength and at 459 nm of emission wavelength. The experimental conditions for ethanol determination are as follows: reaction time is 20 min, temperature is 40 ℃, the concentrations of phosphate buffer solution (pH 7.5) and NAD+ are 0.1 mol/L and 5 mmol/L, respectively; immobilization concentration of ADH is 10 U/L. The linear range for the determination of ethanol is 2.0~15.0 g/L, r>0.9958, the detection limit of ethanol is 1.1 g/L, RSD is 1.9%. IE-EFCA method is applicable for the determination of the alcohol samples in medicine, industry, grocery, and environment.关键词：fluorescence capillary analysis;ethanol;determination;immobilized enzyme
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发布时间：2023-11-28 - 摘要：Abstract:A mathematical model was proposed to predict the pressure drop of vibrated fluidized bed based on the physical significance of the pressure drop of the bed. The first and second fluidization phases including their corresponding critical fluidization velocities were putted forward from the kinetic characteristic of the vibrated fluidized bed. Experiments by using glass beads with different diameter were carried out in the two-dimensional vibrated fluidized bed. The influence of vibration and operation conditions on the pressure drop of vibrated fluidized bed was analyzed. Comparing the model predictions with the experimental data, it showed that the data of theoretical prediction with model were in good agreement with experimental data. An empirical correlation equation to predict the coefficient of vibration energy transfer was established according to the experimental data. The pressure drops of the bed at the first and second critical fluidization velocity were gained. In the end the results obtained in this paper were compared with those of other researchers, which indicated that the model of this research could obtain more reliable result.关键词：vibrated fluidized bed;pressure drop of the bed;critical fluidization velocity
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发布时间：2023-11-28 - 摘要：Abstract:The reaction mechanism of tetrakis hydroxymethyl phosphonium chloride(THPC) and raw collagen were researched by the simulated materials of collagen including glycin, ethylenediamine and hide powder. It was testified that THPC mainly linked with amino groups of collagen as muiltipoints and the combination mole ratio n(p)∶n(N) was 1∶2.2. The combination capacity of THPC was changed with pH and at pH 8.0 the combination amount was the highest with hydroxy and amido groups, although the reaction was weak. The 31P NMR spectrums indicated that trihydroxymethyl phosphonium hydroxide (THPOH) or trihydroxymethyl phosphine (THP) can combine with collagen. The change trends of glutin isoelectric point after treated with THPC, formaldehyde and chrome salt were researched and the results showed that the tanning property of THPC was good.关键词：tetrakis hydroxymethyl phosphonium chloride;raw collagen;tanning
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发布时间：2023-11-28 - 摘要：Abstract:The desulfuration experiments for activated carbon fibre (ACF) and granular activated carbon(GAC) were performed in three systems including SO2+O2+N2(dry state),SO2+O2+N2+H2O(gas state) and SO2+O2+N2+H2O(liquid state), to investigate the surface structural change caused by desulfuratlon. Using SEM, BET, XPS, the morphology of fiber surface, the specific surface of fiber and the amount of the acidic functional groups on the activated carbon surface were determined respectively. The results showed that desulfurating in SO2+O2+N2+H2O(liquid state), the best desulfuration effect is obtained and the amount of H2O in SO2+O2+N2 favour improving the effect of desulfuration. The increase of the amount of COOH(R) groups on the activated carbon improves the effect of desulfuration. The amount of functional groups on the ACF during desulfuration is larger than GAC.关键词：activated carbon fibre;granular activated carbon;desulfuration
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发布时间：2023-11-28 - 摘要：Abstract:N,N,N-trimethyloctadecan-1-aminium chloride was used to prepare 6-dodecylnaphthen-2-ol. And three novel 3H-naphtho［2,1-b］pyrans with long chain substituents were synthesized by the condensation of 6-n-dodecylnaphthen-2-ol with prop-2-yn-1-ols, which are 8-dodecyl-3,3′-diphenyl-3H-naphtho［2,1-b］pyran(NP1), 8-dodecyl-3,3′-bis (p-methoxyphenyl) -3H-naphtho［2,1-b］pyran(NP2) and 8-dodecyl-3,3′-bis(p-n-butoxyphenyl) -3H- naphtho［2,1-b］ pyran (NP3), respectively. The incorporation of long alkyl groups into the rigid naphthopyran results in the liquid crystalline property. The liquid crystal phases of the three compounds were studied by means of differential scanning calorimetry (DSC) and Polarizing optical microscope (POM) with a heating stage. And the photochromis properties, doped in PMMA and dissolved in toluene, were investigated, too.关键词：photochromic;3H-naphtho［2,1-b］pyran;synthesis;phase transferred catalyst;liquid crystalline
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发布时间：2023-11-28 - 摘要：Abstract:The traditional Gene Expression Programming(GEP) has the deficiency of local optimization. In order to solve this problem, VPS-GEP（Various Population Strategy GEP）, an algorithm for evolution skipping from local optimization fast,was proposed.It was proved that the time for per generation evolution increases with the size of population under probability sense. The ability of mining function and efficiency of VPS-GEP was tested by two standard test functions and one standard dataset. The experiments showed that VPS-GEP algorithm decreases the generation stagnancy over 55%.关键词：GEP;Genetic algorithm;function mining;gene diversity;VPS-GEP
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发布时间：2023-11-28 - 摘要：Abstract:a new de-cross-correlation preprocessing idea based on time axis perturbation method (TPM), which utilized the fact that hearing perception is not sensitive to the phase distortion of a speech signal, was proposed to solve the non-unique problem (NUP) in multi-channel acoustic echo cancellation (MCAEC). TPM-based frame time shifting (TPM-FTS) linear method and TPM-based frame expanding compressing (TPM-FEC) nonlinear method were mainly explored. Analysis and experiment showed that, under a condition of the same hearing allowance to the preprocessed speech outputs, both TPM-FTS method and TPM-FEC method have a much better de-cross-correlation performance in comparison with the conventional de-cross-correlation nonlinear preprocessing methods based on amplitude perturbation (APM). TPM-FEC has a more regular rule to follow for the decision of the values of its controlling parameters than TPM FTS, but TPM-FTS has a much easier operation for real-time implementation than TPM-FEC.关键词：time axis perturbation;de-cross-correlation;misalignment;multi-channel acoustic echo cancellation
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发布时间：2023-11-28 - 摘要：Abstract:In order to solve misalignment problem in stereophonic acoustic echo cancellation (SAEC), a nonlinear preprocessing solution based on frequency-shifting was proposed to reduce the correlation between the stereo signals and improve misalignment. Because interference can seriously deteriorate adaptive filter performance in SAEC, the performance of adaptive filter under interference environment was improved by detecting interference and controlling the optimal filter. The computer simulations were implemented with this interference-free SAEC algorithm under complicated environment. The results showed that the algorithm has better performance when it is applied to stereo acoustic echo cancellation.关键词：stereophonic acoustic echo cancellation;nonlinear preprocessing;frequency-shifting;anti interference
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发布时间：2023-11-28 - 摘要：Abstract:The Map Technology of Storage Contents in accordance with even and odd symmetry, the Curve Fitting Technology based on address contents and the Division Difference Technology based on storage contents were used to solve the problem that storage resources is heavily demanded in high precision and high resolution NCO storage. The performance of the Map Technology of storage contents in accordance with even and odd symmetry, and the Curve Fitting Technology based address contents were derived by the mathematical model of content and address. The Division Difference Technology based on storage contents was analyzed qualitatively and simulated with an instance. All the three methods can efficiently reduce resources，which can be reduced to less than three percent by the simultaneous use of two or three efficient technologies.关键词：NCO(Numerically Controlled Oscillation);curve fitting;division difference
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发布时间：2023-11-28 - 摘要：Abstract:In order to confirm danger and security degree of pressure vessel, fuzzy assessment was put forward. Aimed to plastic collapse and fracture assessment of a plane defect of pressure vessel, the least distance ,between assessment dot and failure assessment curve (FAC), was translated into fuzzy degree gene. According to membership grade of the fuzzy assessment, fuzzy assessment model was established, and could be used to confirm the plane defect degree of danger and security. The whole vessel’s defects degree of danger and security were given by an integrated method. The method is intuitionistic, exact and reliable, and also could be applied to other analogous systems.关键词：pressure vessel;defect(s) assessment;fuzzy assessment
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发布时间：2023-11-28 - 摘要：Abstract:Based on the analysis of the normal distortion of contact point of the swinging movable teeth along with surge wheel which subit sine distributing ,the forces and it’s formula which impose on the critical transmission element movable teeth in surge wheel、movable teeth spar peg and contour of internal gear were studied. Furthermore, Based on the Herts theory of elasticity mechanics, the calculation methods for contact fatigue strength about meshing pairs between movable teeth and surge wheel, meshing pairs between movable teeth and contour of internal gear were studied, and the bending fatigue strength of movable teeth spar peg were calculated using material mechanics.The calculation formulas were deduced and CAD was applied based on the methods and formulas.关键词：swinging-movable teeth drivers;contact strength;CAD
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发布时间：2023-11-28
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