最新刊期
卷 39 ， 期 2 ， 2007
- 摘要：Abstract:A projects pursuit regression (PPR) forecasting model of comprehensive indexes for water eutrophication trends was proposed by choosing several relative indexes such as industrial wastewater drainage amount, city sewage drainage amount, industrial wastewater drainage rate up to par, and sewage disposal rate. Through expressing the model as parameter matrix and optimizing the parameter matrix to substitute the conventional smooth multiple additive regression technique, PPR was simple to use. Data relative to society and economy of Taihu Lake basin and water quality of Taihu Lake were used in the model. Particle swarm optimization (PSO) and immune evolution algorithm (IEA) were used for optimizing the parameters in model. The optimized PPR model was used for forecasting the lake eutrophication trends of Taihu Lake in future. Results showed that water quality of Taihu lake will gradually aggravate in future 5～30 years unless more administration or measure will be taken to reduce the pollution. Several regulate projects were put forward in order to simulate the acceptable mode to prevent and harness the eutrophication, which provides the suggestion to guide prevention and administration of lake eutrophication.关键词：particle swarm optimization;immune evolution algorithm;projection pursuit;water quality;eutrophication;forecast
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发布时间：2023-11-28 - 摘要：Abstract:The mean velocity profiles in gravel open channel flow were studied by a series of flume experiments. Velocity measurements were carried out in gravel beds using an Acoustic Doppler Velocimeter.The analysis of velocity profile and flow characteristics such as froude number and relative roughness (R/Ks—the ratio of hydraulic radius and bed roughness Ks which is defined by the bed material diameter d50) were calculated. The results showed that the mean velocity profile mainly depends on froude number and relative roughness. The Log law curve could be used to fit the mean velocity profile with the froude number Fr＜0.41, and the S-curve could be used to describe the velocity profile with 2.0R/Ks5.9, and the transitional location could be well fitted by means of the statistic relationship between relative depth (Z/H) and R/Ks.关键词：velocity profile;relative roughness;Froude number;acoustic doppler velocimeter
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发布时间：2023-11-28 - 摘要：Abstract:An elastic nonlinear damage model of soil was presented according to the deformation property of soil. The soil was considered as a double scalar combining, the one is G material which flexible matrix is only relate to shear modulus of soil ,the other is E material which flexible matrix have only a connection with elastic modulus of soil. Defining double scalar to describe soil damage, respectively, using equivalent strain principle to establish elastic damage constitute relationship, respectively, through mergeing to attain elastic damage constitute equation of soil and obtain the evolution equation based on triaxial test, an elastic nonlinear damage model was presented. The model was applied to calculate foundation settlement and compared with tested results. The results showed that the model is rational.关键词：double scalar;isotropic;elastic nonlinear damage model
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发布时间：2023-11-28 - 摘要：Abstract:Based on a large-scale model experiment,the optimization of the shape of aerator at slight slope of the channel and low Fr spillway tunnel was studied. The result showed that the optimum target of the aerator’s sharp can be measured by the minimum amount of invert flow in air chamber and the minimum distance Tmax (between the zenith of the jet and the baseboard). The main factors of Tmax are the average height of aerator and lateral type of the aerator. The more lower the average height is, the more shorter the Tmax is. The convex aerator in lateral direction can weaken the concave distribution of the water surface in lateral direction and decrease Tmax relatively. The main factors of the invert flow in air chamber are the average height and the height difference of areator. Properly increasing the average height and height difference is good for eliminating the invert flow. When optimizing the shape of aerator at slight slope of the channel, the three dimensional aerator is better than the two dimensional aerator, especially for the convex aerator, which is easy to achieve shorter Tmaxand less invert flow.关键词：flood discharge tunnel;air entrainment to alleviate cavitations;aerator;convex aerator;optimization shape
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发布时间：2023-11-28 - 摘要：Abstract:Model investigations of the primary design showed that the vertical vortex occurs at the intake of the shaft spillway. To eliminate the harmful vortex, three anti swirl piers were set around the intake. Results indicated that the anti swirl effect is good, the water level reduces and the discharge coefficient increases. The RNG k-ε turbulence model was used to simulate the conditions without and with the anti swirl pier, and the funnel shaped vertex was successfully simulated. The calculations are in agreement with the measurement data.The effect of the anti swirl pier was analyzed from the circulation angle. It was shown that the vortex formation accompanies the process of the increase of the circulation, and the circulation can be largely reduced by setting the anti swirl piers. The circulation and vorticity of the water surface while the vortex is stable were also studied. With the increase of the radius, the circulation increases and the vorticity decreases.关键词：vertical vortex;numerical simulation;anti-swirl pier;circulation
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发布时间：2023-11-28 - 摘要：Abstract:A silo discharge tunnel of someone hydropower station was simulated by FLUENT from reservoir upstream to its outlet downstream. The capacity of flood discharge, velocity, pressure were obtained, and were identical with that of the experiments. The simulation indicated that, complicated l flow of silo discharge tunnel with whirling currents can be simulated successfully by the combination of the k-ε double equations turbulent model, VOF method, structured and unstructured grid. The simulation supplies a new method for the study on the silo discharge tunnel with whirling currents.关键词：lood discharge tunnel;silo;whirling currents
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发布时间：2023-11-28 - 摘要：Abstract:In order to depict the complex structure of the natural formations,the indicator function model was used and expressions for the mean, variance and covariance function of the medium parameters of the bimodal formations were derived. A quasi unimodal porous medium was generated. The spectral method based on Kahunen-Loeve expansion was applied in the stochastic analysis of the bimodal media. The water flow in bimodal formations and qausi unimdoal formation were simulated respectively, and the impact of the hydraulic conductivity and parameter α to equivalence between the bimodal and qausi unimdoal formation was analyzed. It was shown that the increase of the total variance of the variable parameters doesn’t lead to a bigger truncation order. If considering the spatial variability of the parameter Ks or α only, the accuracy of the hydraulic head from quasi unimodal formation becomes worse with the increase of the total variance of Ks or α; When Ks or α of the two mediums distinguishes obviously and has small variance, the quasi unimodal formation can substitute bimodal formations; The equivalence is affected more obviously by parameter α than Ks. If considering the spatial variability of the parameter Ks and α at the same time, the larger gap of Ks or α leads to a bad equivalence . The relation between the total variance of Ks or α and equivalence is obscure.关键词：bimodal media;spatial variability;hydraulic head;variance
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发布时间：2023-11-28 - 摘要：Abstract:The random simulation of flood hydrographs is a new way for hydrological safety design. The Gumbel Hougaard Copula was employed to construct a bivariate joint probability distribution for describing flood peak and flood volume, whose marginal distributions are both the Pearson type III. From the derived joint probability distribution of flood peak and flood volume, the flood peak series sample and the flood volume series sample were randomly drawn simultaneously and used to construct the synthetic flood hydrographs. The joint probability distribution of flood peak and flood volume could reflect the correlation between flood peak and flood volume much better than the two separate one-variable probability distributions, one only for flood peak and the other only for flood volume. Compared with other models used for flood random simulation, such as the seasonal first-order autoregressive model and the disaggregation model, the method proposed here performed much better, in terms of the bias and the root mean square error.关键词：random simulation;flood hydrograph;Copula;joint probability distribution
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发布时间：2023-11-28 - 摘要：Abstract:In order to improve the water quality of a waste water treatment plant, the conventional SBR technique was improved by the application of an activated sludge process with suspending filling material into intermittent aeration tanks and the chemical index such as COD,BOD5,NH+4－N,T－P and biofacies were investigated in paralleling experiments. Compared with the traditional SBR, the SBR with suspending filling material could improve obviously bio diversity, the existing type, the allocation of matrix and the mass transfer mode, and shows better tolerance of influent volume and quality. In addition, the removal efficientcy of COD,BOD5,NH+4－N,T－P was greatly increased from the previous 67.9%,81.6%,56.4%,62.5% to 78.4%,88.9%,69.2%,74.2%, respectively.This research focused on the application in SBR with changeable water levels and other intermittent aeration tanks,which is a breakthrough to traditional application of suspending filling material that was usually used in continuous aeration tank.This research had practical value for the improvement of ever built wastewater treatment plants.关键词：suspended padding SBR;COD;BOD5;NH+4－N;T－P
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发布时间：2023-11-28 - 摘要：Abstract:In order to build a new knockdown 3D finite element model of total cervical spine, to evaluate the finite element analysis ability of the model under physiological load vectors, the CT images were pretreated in the MIMICS software, and the data were imported ABAQUS software for 3D reconstruction. A three dimensional (3D) finite element (FE) model of the human total cervical spine, consisting of 35089 nodes ,21894 shell elements, 109746 tetrahedral elements, and 226 spring elements,was developed to model.The model was the bony vertebrae, articulating facets, intervertebral disc, and associated ligaments, validated against the published data under three load configurations: axial compression, flexion,and extension.关键词：knockdown;3D finite element model;cervical spine;stress analysis
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发布时间：2023-11-28 - 摘要：Abstract:The solubilities of propylene in isopropanol and secbutanol aqueous solution in temperatures range from 30 ℃ to 60 ℃, and pressures ranging from 0.3 MPa to 0.9 MPa were measured by a static equilibrium still, in which the mass ratio of alcohol to water were 7∶3, 8∶2,9∶1 and 1∶0 respectively. The solubility of propylene in three alcohol solution under the same condition in the order: secbutanol＞isopropanol＞methanol，and solubiltis increased with increases of alcohol concentrations.Some thermodynamic functions in the dissolution process such as enthalpy and entropy were calculated, and alcohol concentration had relatively greater effect on enthalpy than on entropy. Propylene solubility data and some dissolution phenomena can get explanation from thermodynamic principles, solubility parameters, postulation of “spaces” in associated solution and components structures. Obvious correlation errors and “S” shape of solubility vs concentrations curve was result from that alcohol aqueous solution is greatly deviated from the ideal solution.关键词：solubility of propylene;thermodynamic function;solubility parameters;postulation of “spaces”
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发布时间：2023-11-28 - 摘要：Abstract:Polyurea coating based on polyaspartic esters (PAE) were prepared from synthesized polyaspartic esters (PAE-F) and hexamethylene diisocyanate（HDI）trimer /amine terminated polyoxypropylene (Jeffamine D2000) prepolymer. The surface topography, structure and morphology and electrochemical impedance spectroscopy (EIS) features of the coating under salt fog exposure and UV/salt fog alternating exposure were investigated through SEM, AFM, FTIR and EIS. The results indicated that the performance of the coating was difference when it was tested in different ways. The surface topography and structure and morphology of the coating changed a little after 25 weeks salt fog exposure. As the result, the coating resistance hold high over the period of 25 weeks. But the performance of the coating under UV/salt fog alternating exposure after the same time was totally different. EIS features of the coating showed a rapid reduction over the period of 25 weeks alternating exposure. FTIR, SEM and AFM showed that the molecule chains of the coating were broken, and the ordered structures of hard segment decreased, which indicated that the structure of the coating was destroyed. At the same time, the surface roughness increased, cracks appeared at soft segment phase, and the shape of hard segment phase changed, showing topography changed severely. The study demonstrates that the PAE coating had good resistance of salt fog corrosion and lost resistance after UV/salt fog alternating corrosion.关键词：coating degradation;polyurea;accelerated weathering test;atom force microscopy;structure and morphology
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发布时间：2023-11-28 - 摘要：Abstract:iamond possesses excellent electronic and thermal properties. Uniform diamond films with large area are essential to their industrial applications in electronics. Using microwave plasma chemical vapor deposition technology, diamond films were deposited on the silicon wafer of 51~76 mm in diameter. The surface morphology of the diamond films were observed with SEM, and the resistivity of diamond films were measured with ZC36 high resistance instrument. The uniformity of diamond films were characterized by the uniformity of surface morphology and resistivity. The results indicated that the processes of nucleation and growth of diamond film are different because the substrate temperature, the concentration of different carbonic radicals, and the concentration of atom hydrogen vary with the substrate position. So the uniformity of film is different. The film deposited on 51 mm wafer at the appropriate substrate position is more uniform than that on 76 mm wafer. But the resistivity at the center of the films is similar to that at the edge both on 51 mm wafer and 76 mm wafer, which is up to 108 Ω·cm.关键词：large area diamond films;microwave plasma chemical vapor deposition;resistivity;uniformity
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发布时间：2023-11-28 - 摘要：Abstract:The microwave-absorbing characteristics of ilmenite concentrate, coke, oxidized ilmenite concentrate and composite additive were investigated by means of microwave cavity perturbation, and their temperature rise curves were measured. Analyses of spectrum attenuation and relative frequency shift showed that the microwave absorbing characteristics of ilmenite concentrate and coke were good, but those of oxidized ilmenite concentrate and composite additive were poor. The microwave-absorbing characteristic of ilmenite concentrate pellets containing coke was also good,and that of the metallized pellets reduced under microwave heating was better than that of the pellets without being reduced under microwave heating. The temperature rise behavior were in good agreement with the spectrum.关键词：microwave;ilmenite concentrate;temperature increasing behavior;microwave-absorbing characteristics
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发布时间：2023-11-28 - 摘要：Abstract:Through analyzing the disfigurement of basic attribute oriented induction arithmetic, a new optimized technic and arithmetic based on generalizing hiberarchy of relevancy attribute-oriented was proposed for Chinese medicine prescription data mining. The efficiency of induction and the accuracy of discovery knowledge by the pertinency of relevancy-attribute-threshold and benchmark-attribute-threshold were enhanced，and generalizing hiberarchy and trees for relevancy attribute based on Chinese medical knowledge were established. A new system about Chinese medicine prescription knowledge discovery and analysis was implemented.The effectivity of the new arithmetic was proved by four extensive experiments. The efficiency was heighten above 27% comparing with the conventional arithmetic in the same condition. The speciality knowledge and rules in accordance with Chinese medicine theory can be found more rapidly by the new system.关键词：data mining;relevancy-attribute-oriented induction;threshold of multi-benchmark-attribute;knowledge discovery of Chinese herbal medicine
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发布时间：2023-11-28 - 摘要：Abstract:Traditional Gene Expression Programming(GEP) uses static fitness function. It decreases evolution speed and quality. To solve the problem, outbreeding strategy and dynamic fitness function strategy: outbreed and timely change standard of evaluating individuals were proposed to increase diversity and select excellent individuals; The experiments showed that the performance of traditional GEP is effectively improved by the combination of OBS and DFFS. The average fitness for the best individual is increased by 7%～14%, the maximal fitness is increased by over 7%, and the success rate is increased by over 30%.关键词：Gene Expression Programming(GEP);diversity;fitness function;strong mutation
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发布时间：2023-11-28 - 摘要：Abstract:To efficiently compute the determinants of symbolic matrices arising in science and engineering fields, based on dimension decreasing algorithm and parallel computation of symbolic determinant, a hybrid algorithm,which can convert the computation of a given multivariate determinant to the computation of a univariate determinant,was presented. In addition, the degree of parallelism was enhanced greatly. Experimental results showed that this new algorithm can effectively reduce the intermediate expression swell and deal with some symbolic determinants with polynomial entries in many variables.关键词：symbolic determinant;dimension-decreasing algorithm;parallel computation;resultant
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发布时间：2023-11-28 - 摘要：Abstract:In order to manage the privileges in multi application layers system and make use of the advantage of RBAC in security management, Multi-RBAC, a RBAC model that can be applied in all application-layers was presented. It was applied to all application-layers of system to protect the resources in different layers. Since the roles were defined by the resource privilege in different layers, the Multi RBAC made the classifying of roles more reasonable, the granularity less and the realization of least-privilege principle easier. Furthermore, all requirements of security can be satisfied with the help of other advanced RBAC model. In application, a security management system of CIMS was developed and applied successfully, which showed that the model is feasible.关键词：role-based access control;security model;application-layer;multi-application-layers CIMS system
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发布时间：2023-11-28 - 摘要：Abstract:To provide effective privacy protection for participants in network communication, an improved k-anonymous message transmission protocol was proposed based on Ahn’s work. Some secret sharing techniques were employed to set up session keys for every user within a group and the sum of these keys was kept equal to zero. Each user was required to broadcast a single message encrypted by his secret session key in a communication round. The meaningful anonymous messages could be recovered by multiplying all the broadcast data together. A sub-protocol with constant round complexity was also constructed based on the witness indistinguishable proof techniques to guarantee fairness. The computation and communication complexity of the improved transmission sub-protocol was reduced by a factor of M (the number of users within a group), and that of the sub protocol with fairness by a factor of λ (the security parameter). It can be proved that the anonymity of the improved protocol is based on the Decisional Diffie-Hellman assumption.关键词：anonymous communication;k-anonymity;proof of knowledge;Decisional Diffie-Hellman assumption
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发布时间：2023-11-28 - 摘要：Abstract:The image scanned by embedded biochip scanner was filled with many high density of micro-spot arrays. In order to meet the needs of intelligentizing and automatization, a method was proposed to locate the target spots on the biochip image. Firstly, an erosion method based on morphology was applied to this image, and the outline of the spots was got. With horizontal projection was vertical projection, the two-dimension gray matrix was transformed to two one dimension lists. Combined with Fourier transform method and power spectrum transform method, column distance and row distance were calculated for us to search the center in the lists. In view of the fact that the outline image will show two sub-peaks if it is projected, spot diameter was estimated easily. Finally, depending on gravity method and adaptive step length variation searching method, the target locating and segmentation were realized accurately. The method was carried out by C programming language and tested on Pentium Ⅳ 2.2 GHz.The locating process spent 1.8 seconds to dispose a image with 304 spots(row:16,column:19). Locating accuracy came to a hundred percent.关键词：biochip;target locating;target segmentation
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发布时间：2023-11-28 - 摘要：Abstract:The helicopter anti-prang experiment dummy designed by employing human parameter stationary design method and bio-mechanism parameter dynamic design methodology, has Chinese parameter and is anthropomorphic , bio mechanics emulation and human structure equivalent. The calibration of the helicopter anti prang experiment dummy is carried out. The calibration results indicate that the main specifications of the helicopter anti prang experiment dummy meet the requirement of the same kind abroad dummy.关键词：helicopter anti-prang experiment dummy;dummy calibration;bio-mechanics parameter
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发布时间：2023-11-28 - 摘要：Abstract:To apply the intelligence technology in CAD design domain effectively, a hybrid case reasoning mechanism, which supports product variant design based feature and the self learning of adaptation knowledge, was proposed. The mechanism was based on CBR and combined Fuzzy set theory and SCBR（secondary CBR）together. Fuzzy set theory was employed to perform approximate matching and thus to reduce potential noise in case retrieval, and the SCBR technology was used to implement the adaptation and reuse for case. The application result showed that the hybrid mechanism could provide the designers with effective design decision and reduce the requirement of correlative domain knowledge for them.关键词：hybrid case reasoning;variant design;CBR;Fuzzy set;SCBR
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发布时间：2023-11-28 - 摘要：Abstract:Considering the pivotal period that a glass plate is being bent to tapered windscreen, a new forming method and a 3D model for this method was presented, and an accurate forming algorithm was introduced. Two functional relationships, one is between the cable’s pulling displacement and the bended Plexiglas’s wrap angle, the other is between angular speed and cable’s pulling speed, were deduced to control the forming process. In this model, the position accuracy, foming speed and the synchronization of two sides’wrap angles can be definitely ensured. This method was proved in practical forming system.关键词：windscreen;bending;wrap angle;shaping control
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发布时间：2023-11-28
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