最新刊期
卷 39 ， 期 6 ， 2007
- 摘要：Abstract:The behaviors under impact condition are different from the ones under quasi static condition. However, because of the complexity of dynamic fracture problems, the analytical result of stress intensity factor of such simple sample as three point bending beam hasn’t been determined. To satisfy the request of theoretical and experimental analysis,the finite element method program LS-DYNA is used to analyse the dynamic process (including the sine,linear,anomalistic progress) of three point bending beam under impact load.The dynamic stress,strain field at crack tip and corresponding curves of force time and displacement time in the area of crack tip are obtained. The method of determining the energy release rate and dynamic stress intensity factor under impact load is obtained by virtual crack closure method,the curve of GI (energy release rate) vs.time,KId (dynamic stress intensity factor ) vs.time under different impact loads are calculated,and according to KId-time curves the corresponding dynamic stress intensity factor of the extend time which is determined by experimental method in the literature,called dynamic fracture toughness,is determined.The results got by FEM are compared with the experimental results and show good agreement with experimental data,and more it has higher precision.As a result,this method can be used to the computtion of dynamic fracture parameters.关键词：impact loading;three-point-bending sample;finite element;virtual crack closure technique;dynamic fracture parameter
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发布时间：2023-11-28 - 摘要：Abstract:On the basis of evaluation index system of Chaohu Lake water quality security and its grading criterion, an objective weight structure of evaluation indexes consisted of attribute weights and sample set weights is proposed, the attribute weights can be computed using accelerating genetic algorithm based correspondence factor analysis, the sample set weights can be computed using accelerating genetic algorithm based projection pursuit method, the objective combination weights of evaluation indexes can be computed using minimum relative information entropy principle, which forms a model for evaluating Chaohu Lake water quality security, named CFA-PP for short. The applied result of CFA PP shows that the most important four indexes are total phosphorus, chlorophyll a, ammonia nitrogen and total nitrogen, respectively; the water quality security grade of the whole lake is between “relative insecurity” and “insecurity” grade; the most effective approach to improve water quality security of Chaohu lake is to reduce influent trophic salt loads of phosphorus and nitrogen. As a general evaluation method driven by data, CFA-PP can be widely applied in different water quality security evaluation.关键词：management of watershed water security;water quality security evaluation;correspondence factor analysis;projection pursuit method;principles of information entropy
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发布时间：2023-11-28 - 摘要：Abstract:Based on the failure safety theory, the study on the failure safety cable systems of the bridges was carried out. The uncertainty of the statistical fatigue life estimation was avoided. The failure safety cable systems make it possible that the bridge will not collapse abruptly and unexpectedly due to the failure of some cables,and the repair of the damaged or broken cables can be realized right after the cable failure happens without the whole bridge being closed for traffic.关键词：bridges;fatigue failure;failure safety theory;tensile cable system
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发布时间：2023-11-28 - 摘要：Abstract:Understanding flow resistance in a compound channel with totally mobile bed is important for determining the stage discharge curve and supporting the management of fluvial processes. The paper experimentally studies the characteristics of flow resistance for overbank flows in a compound channel with totally mobile bed composed of non uniforme sediment, including the variation of energy loss and resistance coefficients along the channel after armoring is completed. The experimental results show that it is difficult to obtain uniform flow in this type channel. By analyzing the experimental data, it is found that water surface slope is largely different from energy slope for this type of channel. For this type of channel, under the given condition, the resistance coefficients don’t keep constant, while they vary along the channel. The characteristics show that flow resistance in compound channels with totally mobile bed is more complex than that in compound channels with rigid bed. As a resistance, it is more difficult to predict conveyance capacity and sediment transport capacity in compound channels with totally mobile bed than in ones with rigid bed.关键词：compound channels;mobile bed;energy loss;resistance coefficients;overbank flow
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发布时间：2023-11-28 - 摘要：Abstract:Comparability of roughness is studied experimentally and theoretically in a long tunnel in physical model.These results show that comparability of roughness can be achieved by adoptting the rational technique on a base of keeping their positions of the tunnel and the riverway.The length of tunnel with the higher velocity is replaced with the length of tunnel with the lower velocity.The theoretical value of the velocity and the discharge are in agreemant with the revised value by measured in revised physical model. The method is suitable to revise roughness on the wall of the pressure tunnel and the open channel in order to obtain the practical experimental data.关键词：long tunnel;revision of roughness;comparability of physical model;experimental investigation
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发布时间：2023-11-28 - 摘要：Abstract:The corroded expansion of grouted bolt often leads to the failure of slope anchor structure in underground special environment. Based on the deformation compatibility relation among bolt,grout material and surrounding rock,and by investigating factors such as the amount of bolt corroding,the property of grouted material,the protective thickness, as well as the mechanical properties influencing the corrode expansion force of the system, a mechanism model of corroded expansion is developed for the corroding grouted bolt.The results show that the corrode expansion force of bolt increases with the increase of the bolt corroding ratio,and decrease with the increase of protective thickness or grout strength.The corrode expansion force between grout and rock increase with increase of surround rock strength and grout strength.However,the corrode expansion force between bolt and grout increase with increase of surround rock strength,but decrease with increase of grout strength.关键词：grouted bolt;corroded expansion model;elastic theory
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发布时间：2023-11-28 - 摘要：Abstract:Debris flows always occur in small drainage basins in mountainous areas, i.e., in basins almost in size of less than 50 km2 in China. Nearly 6000 basins out of the collection of the Database of Debris Flow in China are taken into account in the context of the country and several particularly chosen regions where debris flow is frequently consequential to reveal the relationship between drainage area and occurrence frequency. Statistics of these basins indicates a distribution in the general exponential form, i.e., the generalized Gamma distribution, which takes Weibull, Gamma, and exponential distribution as its particularities.The Weibull distribution is perhaps the most likelihood that, in a natural way, defines a hazard rate for the weighting probability of the basin area; and, of more significance, from which results a failure mechanism of the debris-flow system.Finally, observational data of debris-flow-surge discharge of Jiangjia Gully is mustered as surrogate variables to confirm the general magnitude-frequency relation of debris flow. Distribution in the same exponential form as the drainage area has been found, which implies a correlation between debris flow and the spatial features of a valley.关键词：debris flow;basin area;probability distribution
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发布时间：2023-11-28 - 摘要：Abstract:Damage is an important mean for the analysis of the deformation and fracture of rock, and statistical damage theory have received much attention in the study of rock damage. Initial damage coefficient, reflecting the inhomogeneous and non-linear of the rock to a certain degree, was proposed by analyzing the shortage of the statistical constitutive model of rock damage. By considering characteristic parameter and geometric condition of rock complete stress strain curve, the difficulties of calculating the parameter of constitutive equation in the traditional method was overcomed, and the calculational precision was improved. At last, based on the triaxial compressive test results of sand rock from a practical engineering, the statistical constitutive model of rock damage was confirmed, and the size-up of q was discussed.关键词：rock;damage;constitutive model
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发布时间：2023-11-28 - 摘要：Abstract:Three-dimensional elasto plastic behaviors of cracks in TiN coatings under the cyclically indenting and sliding contacts of an elastic sphere are studied using finite element method. The stress distributions in the coating and substrate, and the fracture intensity,J integral, of cracks at the surface and interface are calculated. It is shown that the maximum stress is near the contact boundary, where the fatigue cracks will be easily initiated under the cyclic loadings. The parameters, such as thickness of coatings, substrate material, shape and obliquity of crack, have obvious influence on J-integrals of surface and interface cracks.
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发布时间：2023-11-28 - 摘要：Abstract:To master the mechanical property and to analyze pilot project of the fiber plasterboard filled with reinforced concrete（Rapid Wall）, according to the material characteristic and the idea of micro-and macro-model, a macro-model basing on the idea of fiber model is put forward, which is applied to analyze nonlinear characteristic of composite wall. The macro model is composed of macro fiber element that only resists axis force and moment of the composite wall, and macro shear element that only resists shear force of the composite wall. Stiffness matrix of the model and constitutive models of element stiffness are presented. The elasto-plastic push-over is carried out to the four fiber plasterboard filled with reinforced concrete with the macro-model. The computational results are all close to those of experiments, which show that the macro model can be used to analyze the dynamic properties of composite material and has relatively high accuracy.关键词：rapid wall;macro fiber model;RC core column;pushover
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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 problems of elasticity. The stress analysis of multi-span continuous deep beam subjected to distributed load has been performed. Meanwhile, considering effect of supported width, the divergence of solution on some bottom boundary points is eliminated and the static equilibrium as a whole is reflected. The present method has no coherence with Airy stress function, which provides a new approach for traditional elasticity analytical method apply to solving the practical engineering problems.关键词：elasticity;sum function method;deep beam;stress;series solution
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发布时间：2023-11-28 -
Stress Analysis of the Dynamic Process Simulation of Canine Tipping Movement during a Therapy Period
摘要：Abstract:With combining bone remodeling with finite element analysis, the dynamic process of canine tipping movement during a therapy period is simulated and the stress distribution in each phase is obtained. A three dimensional finite element model including tooth, periodontal ligament, pulp and alveolar bone is established according to a mandibular canine of an orthodontic patient. Through finite element analysis, the strain distribution of the model is obtained under the initial moment. The normal strain on the surface of the periodontal ligament is assumed as the mechanical stimulus proportional to the absorption rate of alveolar bone in each week. Then the second model based on the moved canine is constructed.With the decreased moment, the computed normal strain of the periodontal ligament surface is also used for the next phase of tooth tipping movement. In a therapy period, the relationship between the time and the degree in the numerical simulation is consistent with typical tooth movement. The stresse in the alveolar bone and periodontal ligament gradually decreases and the maximum stress appears at the tooth apex or the crest of alveolar bone. The dynamic process simulation of canine tipping movement is achieved. It will be helpful for the planning and forecast of the therapy.关键词：canine;tipping movement;dynamic process;finite element method (FEM)- 4
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发布时间：2023-11-28 - 摘要：Abstract:In order to develope the technology of urea phosphate, the reaction kinetics of dissolving urea in phosphoric acid was studied under the condition of eliminating liquid diffusion have been studied. The effects of reaction temperature, urea particle size and phosphoric acid concentration on the dissolution were investigated. Reaction kinetic equation of approaching first order reaction was obtained throughout analyzing and handling of experiment data for caculating some parameters.The results is a good foundation for further research and industrial application.
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发布时间：2023-11-28 - 摘要：Abstract:Polyurethanes with pedant quaternary ammonium salts (QAS) have been shown potent antimicrobial properties against gram positive bacteria but less sensitive to gram negative ones. Besides, due to using a large amount of QAS chain extenders, Polyurethanes with pedant QAS have been proven to be high water adsorption and even water soluble. In order to solve the two problems mentioned above of biocidal polyurethane with QAS groups, Polyurethanes were synthesized from the chain extender with pendant bis ammonium salts and verified by GPC and 1HNMR. The degree of microphase separation of sythesized polyurethans was characterized by FTIR and DSC. It was found that the phase separation of the two sets of the polyurethanes decreased with increasing the amounts of bis-ammonium salts chain extenders as proven by DSC and FTIR.关键词：bis-ammonium salts;polyurethanes;synthesis
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发布时间：2023-11-28 - 摘要：Abstract:The microwave absorbing characteristics of the mixtures of carbonaceous reducer and zinc kiln slag were measured by the technique of microwave cavity perturbation and the relationships between P(P=ωε″E2V) and the microwave absorbing characteristic of the mixtures were studied. The results indicated that when the particle size of the mixtures is in the range of 147～175 μm, the optimal proportions are 18% (coconut’s carbon:zinc kiln slag),28% (coke：zinc kiln slag) and 16% (graphite：zinc kiln slag),respectively. Under those proportions, ε″ and P reach sharply to maximums and the characteristics of microwave absorbing of mixtures change.关键词：zinc-kiln slag;proportions of carbon;carbonaceous reducer;characteristic of microwave absorbing
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发布时间：2023-11-28 - 摘要：Abstract:The individuals of Gene Expression Programming (GEP) represent the candidate solutions of the problem. The determining of the length of an individual is a dilemma when there is no prior knowledge available. Either long or short length decreases the efficiency of GEP. The efficiency impact of the individual’s length was analyzed, Open Reading Frame (ORF) filter was designed to modify the coding region dynamically based on the evolution progress of the best individual, and the effectiveness of ORF filter was demonstrated. The experiments showed that solutions with higher fitness can be found and the average runtime is reduced by 17.0% in the same number of generations by introducing ORF filter into original GEP.关键词：gene expression programming;Open Reading Frame;individual
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发布时间：2023-11-28 - 摘要：Abstract:Many clustering algorithms have to need a number of clusters before clustering.In order to tackle this problem,a novel GEP-Cluster (Gene Expression Programming clustering) algorithm was proposed. The main contributions include: 1) proposing the GEP Cluster algorithm to find the best clustering via GEP evolution, 2) proposing AMCA algorithm to auto merge cluster, 3) finding the best clustering without any priori knowledge by the GEP Cluster algorithm.Extensive experiments showed that GEP-Cluster algorithm is effective in clustering without any domain knowledge, and the average clustering accuracy is almost 96%.Keywords关键词：clustering;gene expression programming;K-Means algorithm;evolutionary computation
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发布时间：2023-11-28 - 摘要：Abstract:In order to satisfy the requirements of functionality and security requirements for electronic tendering,an identity based sealed tender scheme was presented. Every tendering was supervised to prevent collusion by multiple third parties. A readable and globally unique identifier as a public key was applied to achieve replay-attack resistance. To achieve the relative privacy, the links between tenders and the corresponding tenderers were concealed, but the tenders were not concealed. Price flexibility and rule flexibility were implemented to meet the complicated tendering condition. The analysis showed that the scheme is a feasible and secure solution for electronic tendering.关键词：sealed tender;identity based cryptosystems;relative privacy
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发布时间：2023-11-28 - 摘要：Abstract:The security of XUE-CAO proxy blind signature scheme was analyzed, and two forgery attacks,which make the original signer or any other third party can forge a valid proxy blind signature,were pointed out. Furthermore，to improve XUE-CAO scheme，an improved proxy blind signature scheme is proposed. While reserving the advantages of the original scheme, this scheme is capable of resisting any forgery attack,which can be used to build more secure system.关键词：proxy blind signature;strong unforgeability;universal forgeryMambo
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发布时间：2023-11-28 - 摘要：Abstract:In order to carry out the risk quantification for the information system,the risk distribution was proposed based on resources distribution of information system, and the improvement of elements relationship model for risk assessment. In quantifying risks,Analytic Hierarchy Process (AHP), Fuzzy Comprehensive Evaluation (FCE), F-statistic and Least Square Estimation (LSE) was applied to get hierarchy of risk factors. The criteria of relativity and formulated relativity functions were established.
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发布时间：2023-11-28 - 摘要：Abstract:In terms of participating in congestion monitor and recovery, the active router always dropped packets passively to relax congestion although it removed feedback delay. A new active congestion control algorithm based on the XCP mechanism was put forward. In this algorithm, every active packet included the key congestion parameters which would be modified according to the current network situation. The experimental results showed that this new algorithm can achieve fair, efficient use of bandwidth and reduce the rate of packet dropping.关键词：active network;ACC;TCP;XCP
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发布时间：2023-11-28 - 摘要：Abstract:In order to improve the security of secure communication systems based on chaos synchronization, a new four dimensional hyperchaos system was built by adding an additional state into the three order Lü system. Some of its basic dynamical properties were studied briefly, such as the feature of equilibrium, the bifurcation diagram, the hyperchaos attractor, Lyapunov exponent and fractal dimension.An electronic circuit was designed to realize the four dimensional hyperchaos system. A method of chaos synchronization between the four dimensional hyperchaos system and its duplicate system using linear feedback control was proposed. Based on the Lyapunov stability theory, the range of feedback gain was derived.Computer simulation showed that the hyperchaos system has variety of states and chaos synchronization can be realized using linear feedback control.关键词：linear feedback control;chaos synchronization;the four-dimensional hyperchaos system
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发布时间：2023-11-28 - 摘要：Abstract:Since the requirement of Independent Component Analysis (ICA) was multi-channels signals, the Empirical Mode Decomposition (EMD) was proposed to construct the multi channels signals and a new method of eliminating noises in partial discharge signals of power transformer was presented. Using this method in online monitoring of transformer, the partial discharge signals wave and the information of the relative range between the signals and the time point of the max-value can be drawn from narrowband interference and white noise very well. The artificial data and the on site test results showed that the performance of this method was good.关键词：partial discharge;noise elimination;Independent Component Analysis;empirical mode decomposition
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发布时间：2023-11-28 - 摘要：Abstract:A crossed fringe pattern plane was used as the model plane for camera calibration. The local world coordinates of the model planes can be decided by the previously known phase distributions on the planes. So the relationships between the 2D image coordinates and the 2D world coordinates will be set up, and the calibration procedure will be done by plane-based camera calibration technique after measuring the phase distributions of the reference plane at several different orientations. This avoids the complex procedure of extracting the control points from images, produces mass volume calibration data, and leads to the high-accuracy calibration results even with the lest orientations in need. Both computer simulation and real data confirm the proposed technique is reliable, high accurate and high speed.关键词：Fourier transform profilometry;camera calibration;3D measurement;2D plane-based object;planar crossed fringe patterns
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发布时间：2023-11-28 - 摘要：Abstract:In order to filter out the unwanted colors for three primary luminescent materials, one multi-layer interference dielectric long wavelength pass filter for red screen, and two short wavelength pass filters for green and blue screens were designed and fabricated on the luminescent screens, respectively. Layer-symmetric films were used to design the filters and the conjugate gradient method was used to optimize the design by MATLAB.17-layer filter for red screen,15-layer filter for green screen，and 15-layer filter for blue screen have a total thickness of 1113.9 nm, 1504.3 nm and 1436.0 nm, respectively. The obtained filters have good characteristics within the whole visible wavelength bandwidth and the incident angle range between 0°~30°. The manufacturing tolerances on material refractive index and film thickness are reasonably large.关键词：interference filter;up-conversion of near infrared light;color saturation
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发布时间：2023-11-28 - 摘要：Abstract:To analyze the dynamic characteristics of the gravity support system of ITER, according to the characteristics of cyclic symmetry of the gravity support system of ITER, the 3-D FEM model with 20 degree sector of the gravity support system was built by using ANSYS. Meantime, a mesh dividing method, which has high precision and an acceptable calculating scale, was used. After the mesh of the model had been divided, the contact elements were defined on the interfaces between flanges. The modal analysis of the gravity support system was made and the first ten natural frequencies and vibration modes of the gravity support system were solved by using Block Lanczos method. The results of the modal analysis can be used to the design and improvement of the gravity support system of ITER.关键词：ITER;finite element;modal analysis;cyclic symmetry
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发布时间：2023-11-28 - 摘要：Abstract:For the need of establishing construction machinery customization system, through the analysis of Itten and Ostwald color theory, 12-color circle of Itten was improved for gradient color circle. Based on gradient color circle and improved Ostwald color harmony theory, an algorithm of section framed circle star harmony was proposed. The advantage of the algorithm is that choozing a main color and confirming the number of different colors in one combination, harmony colors would be worked out automatically. Program compiling was implemented by using C++. Using the platform of Quest 3D and its self development-kit, a sub color customization system for construction machinery was established.The harmony color would be created automatically by computer after a main color was selected by customer. The application of this developed system proved its fine practical value for projects.
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发布时间：2023-11-28 - 摘要：Abstract:In order to accurately evaluate vehicle movement stability, a test system for vehicle movement stability based on real time kinematic (RTK) differential GPS technology is successfully developed. Vehicle movement parameters, which represent the vehicle motion performance, can be acquired in real time with this test system, thereby achieving vehicle movement stability testing and evaluation. In addition, a superior approach for measuring vehicular velocity is contrived, which solves the difficulty in verifying the accuracy and precise of velocity measuring with GPS. The hardware composing and software flow are introduced. The real vehicle experiment results indicate that the test system for vehicle movement stability is feasible and advanced.关键词：real time kinematic (RTK) differential GPS;vehicle movement stability test;vehicular velocity;real vehicle test
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发布时间：2023-11-28 - 摘要：Abstract:At present, the portable instruments for radon measurement are poor measurement sensitivity, large volume and high power consumption. On the basis of the passive indirect measurement method, Au-Si surface barrier detector, charge sensitive preamplifier and main amplifier were integrated, and a high resolution narrow pulse peak hold circuit was designed successfully. With small volume and low power consumption, the part of data processing and control, based on the mixed-signal system, can make field analysis, field print, data uploading and so on. The calibration was made using the calibration method of unsteady concentration, and the results showed that this instrument is evidently better than MODEL1027 of USA in standard deviation of coefficient.关键词：indirect measurement method;peak hold circuit;mixed signal system;measurement sensitivity;standard deviation of coefficient
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发布时间：2023-11-28
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