最新刊期
卷 42 ， 期 6 ， 2010
- 摘要：Abstract:In order to resolve the problem of imprecise and complex operations of triangular fuzzy numbers for quantitatively describing the grade of risk and importance of risk of water security system by the existing method and the problem that its aggregative risk assessment result is only real number without determining the uncertainty of the assessment result, on the basis of the indexes system of water security risk assessment according to system vulnerability concept, Monte-Carlo method was presented to simulate triangular fuzzy numbers for transforming the operations of triangular fuzzy numbers and their functions into the conventional operations of real numbers, and then an aggregative Risk based Water Security Assessment method using Stochastic Simulation and Triangular Fuzzy Numbers, named RWSA-SSTFN, was established. The application results of RWSA-SSTFN showed that the assessment of RWSA-SSTFN expressed by confidence intervals can provide more reliability information than that of common evaluation methods, which can reflect practical conditions of the aggregative risk assessment method for water security system, and that RWSA-SSTFN is intuitionistic, simple and general. RWSA-SSTFN can also be applied to comprehensive risk assessment problems of different resource and environment security systems affected by many uncertainty factors such as randomness, fuzziness and the shortage and imprecision of datum information.关键词：water security system;risk assessment;grade of risk;importance of risk;triangular fuzzy numbers;Monte-Carlo method
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发布时间：2023-11-14 - 摘要：Abstract:The hydraulic characteristics of smooth spillway, stepped spillway and pre-aerator stepped spillway were studied. The experimental investigations showed that the pre-aerator equipment can not only keep the stepped spillway’s large energy dissipation ratio but also protect the step’s surface from cavitation erosion by controlling the aeration concentration in stepped spillway. Model test results indicated that the energy dissipation ratio of the pre-aerator stepped spillway can reach to 70% at various discharge. The measured value of the aeration concentration was bigger than 5% at the vertical surface of steps. The -aerator stepped spillway had a better characteristic of against cavitation erosion and its energy dissipation ratio was higher than that of the smooth spillway. The pre aerator stepped spillway can be applied to the practical engineering with high water head and large unit discharge(exceed to 50 m^3/s).关键词：pre-aerator slot;stepped spillway;hydraulic characteristics;air entrainment and cavitation erosion
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发布时间：2023-11-14 - 摘要：Abstract:The RNG k-ε turbulent model with VOF method was used to simulate the flow in stilling basin with flaring gate pier, which was served for shape optimization of engineering application. The Fr Number of this flow was no more than 3.0. The calculated result agreed well with the experimental data.关键词：turbulent numerical simulation;VOF;hydraulic characteristics;stilling basin;flaring gate pier;shape optimization
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发布时间：2023-11-14 - 摘要：Abstract:Dagangshan Hydroelectric Power Station is a large-scale hydroelectric power station developed recently in the main stream of Dadu River. According to the complex geological structures of Dagangshan arch dam，the stabilities of the dam abutment was studied by the comprehensive method of 3D geomechanical model test. Considering both factors of overloading and strength-decreasing, the failure model test was carried out. The deformation character of arch dam abutment was studied, the failure process and final failure pattern of dam abutment and foundation were obtained, and the comprehensive safety factor of dam abutment was determined as 5.0~5.6.关键词：complex foundation;geomechanical model;abutment stability;comprehensive method
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发布时间：2023-11-14 - 摘要：Abstract:Tennant method was widely applied to river ecological runoff calculation, but it was very difficult to confirm perennial average flow by this method, and the average sometimes did not accurately reflect the central tendency of overall distribution. To deal with this problem, the statistical character of the practical data was studied and the median and mode theory was introduced to avoid extreme data effect to statistics by improved Tennant method, and the typical flow process was finally found out. The application on ecological runoff calculation of Luan River downstream and the comparison between this method and old ones showed that the improved method was much more reasonable.关键词：ecological runoff;Tennant method;median;mode;typical flow;Luan River downstream
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发布时间：2023-11-14 - 摘要：Abstract:The mean head gradient plane of the irregular triangle column volume was proposed to solve the simplified numerical simulation problem of groundwater in irregular and declining aquifer-aquitard system. According to the results of water balance in a finite volume based on the mean head gradient plane, the net lateral flux and elastic storage of the element were calculated. The vertical water flow flux between upper and lower layers was computed by the finite difference method. The simplified 3D numerical model was obtained from the proposed method and applied to simulate the groundwater flow in different hypothetic groundwater exploitation conditions. The comparison of the results of the proposed model with Visual Modflow and Feflow showed good agreement of the three models and its advantage over Visual Modflow for the declining and irregular aquifer-aquitard system.关键词：groundwater;simplified 3D numerical model;declining aquifer-aquitard system
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发布时间：2023-11-14 - 摘要：Abstract:The granite samples collected from the underground powerhouse of Pubugou Hydropower Station were tested on MTS815 Flex Test GT rock mechanics test system under uniaxial compression condition. During the whole test process, the acoustic emission events were monitored by PCI-2 based AE system. Based on the cylinder-covering spatial fractal model, the spatial distribution features of AE events and the changing law of spatial fractal dimensions at different stress levels were studied. The experimental results showed that there are little AE events at low stress stage. The AE events become gradually active as the stress increasing and the cumulative number of AE events raises exponentially when the stress is close to the peak strength. The fractal dimension values gradually decrease from 3 to 2 with the increase of stress and reach the minimum value when the loading is equal to the peak strength. At the later stage of elastic deformation, the spatial fractal dimension values decrease obviously with the microcracks in granite sample gathering in the nearby field of failure surface. The complexity of AE events spatial distribution can be characterized properly by its fractal dimension, and these results agree with the research results of rock burst in references.关键词：rock failure;Acoustic Emission (AE);fractal model;spatial distribution
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发布时间：2023-11-14 - 摘要：Abstract:16 square-section concrete columns confined by CFRP sheet were tested in uniaxial compression involved in different preload ratio and CFRP plies. The failure characteristic and mechanics behavior of confined concrete columns were presented, and the descending of the peak stress and strain of confined concrete due to preload were analyzed. The experimental results indicated that the confinement effect of CFRP was influenced by preload ratio observably. The second stiffness, the peak stress and strain declined with preload ratio ascending, and the extent developed with the enhancement of CFRP ply.
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发布时间：2023-11-14 - 摘要：Abstract:Base on several large-scale triaxial test results of the red layer non-cohesive soil rock mixture in Sichuan Basin, variation rules of strength parameters with the dry density, gravel content and the maximum particle size were studied. The relational expression between the strength parameters and the control factors was obtained by the least square method. The multi-factors predictive mathematical model of the earth-rock mixture strength parameters was established and confirmed. This prediction model is useful for the strength parameters prediction of the similar earth-rock mixture.关键词：red layer non-cohesive soil;soil rock mixture;strength parameters;mathematical model
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发布时间：2023-11-14 - 摘要：Abstract:Based on ADINA program, numerical analysis was applied to study the hysteretic behavior of K-type welded outer sleeve RHS joints subjected to axially cyclic load, using the nonlinear method of Newton-Raphson with Low-Speed Dynamics Damping Factor. Considering the influencing factors such as elastic-plastic material, large deformation, and tearing failure, the skeleton curve and ductility coefficient were obtained, which were the main indexes reflecting RHS joints seismic behaviors. By changing the geometrical parameters of the outer sleeve joints(the length and thickness of the outer sleeves, the branch pipes to main pipes width ratio), the variation regularity of the joints hysteretic behaviors was studied and the restoring force model was proposed. The analysis showed that the hysteretic behavior of K-type welded outer sleeve RHS joints is much better than that of the non-strengthen joints, and it can improve the ultimate capacity by raising the thickness ratio between the outer sleeve and the chord.
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发布时间：2023-11-14 -
A New Method on Ascertaining Designed Thrust for Timbering Pile Based on Transfer Coefficient Method
摘要：Abstract:To overcome the problem that the transfer coefficient method used for the calculation of the landslide thrust behind anti-slide pile was viable, and the designed thrust could not be ascertained through the calculation of sliding-resistance force before anti-slide pile, a new method of calculating the designed thrust of timbering pile which based on transfer coefficient method was put forward. Based on the idea of transfer coefficient method, under the engineer safety request, the residual sliding force was calculated from up to down, and residual sliding-resistance force was inversely calculated from down to up simultaneously. Designed thrust of the setting of timbering pile was equal to horizontal difference between residual sliding force and residual sliding-resistance force, and the expression of designed thrust was presented. Compared with other methods of calculation, this method was proved reasonably.关键词：timbering pile;transfer coefficient method;residual sliding force;residual sliding-resistance force;designed thrust- 3335
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发布时间：2023-11-14 - 摘要：Abstract:The long-span cable nets are widely used in practical engineering. For the purpose of providing a basis for anti-wind and anti-earthquake design of this structure, the dynamic characteristics of elliptic hyperbolic paraboloid cable nets were analyzed. Taking the temperature and geometric nonlinearity into consideration, the nonlinear vibration equation of elliptic hyperbolic paraboloid cable nets was derived by assuming the support system as a continuum membra. By the Galerkin method, the partial differential equation was transformed into ordinary differential equation which was solved with L-P method and KBM method. The effects of temperature, amplitude, and exterior excitation on the nonlinear vibration were discussed with the calculation example. The results indicated that the natural frequency of cable nets decreased with the increases of temperature, while the frequency increased when amplitude increased. In addition, its nonlinear vibration frequency was higher than linear vibration frequency. The steady state vibration of cable nets under harmonic load was simple harmonic vibration with the same period of exterior excitation.关键词：vibrations;cable nets;dynamic characteristics;long-span
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发布时间：2023-11-14 - 摘要：Abstract:An additional stress, called edge stress, may be generated in the joint between a thin walled centrifuge bowl and a top annular plate or a bowl bottom. It is a kind of dull, monotonous or time-consuming work to calculate it in a traditional method. And for the bowl with a complicated shape it is extremely difficult to complete the calculation. The equivalent stress at the joint was quantitatively analyzed under dimensionless theory in the finite element analysis method (FEM). Two dimensionless quantities were defined. One is the edge stress coefficient βwhich is equal to the ratio of the equivalent stress at the joint to the circumferential membrane stress of bowl wall. The other is the edge connection thickness coefficient α which is the ratio of thickness of the bowl wall to the thickness of the top annular plate or bowl bottom. The effects on the equivalent stresses at the joint of α value, fillet radius, centrifugal pressure of suspension, rotational speed, and height-to- diameter ratio on β value were investigated. The results showed that β value reduces when a value increases. The influence of fillet radius is obvious. When fillet radius reduces, β value increases. β value increases with the increasing of the centrifugal pressure of suspension. The rotational speed and height-to-diameter ratio have little influence to βvalue. Under the conditions of the numerical simulation,the maximum edge stress coefficient at the joint of top bowl rim is 3.20 and that of bowl bottom edge is 2.91. Finally, the data for calculating the equivalent stresses at the joint of a given centrifuge bowl were contributed, which would provide valuable information for designing the centrifuge bowl in engineering practice.关键词：finite element;cylindrical centrifuge bowl;edge stress
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发布时间：2023-11-14 - 摘要：Abstract:Precipitation polymerization was used to prepare molecular imprinted polymers (MIPs) of chloramphenicol. using chloramphenicol as template molecular，MAA as the functional monomer，ethylene glycol dimethacrylate as the cross-linker (chloramphenicol∶MAA∶ethylene glycol dimethacrylate was 1∶4∶20 (mole ratio))，acetonitrile-water system as the porogenic solvent，and 2,2’-Azobisiso butyronitrile as the initiator，chloramphenicol molecular imprinted polymer microspheres with an average size of 13.83 μm were synthesized with water bathing at 60 ℃ and stirring at the speed of 400 r·min^-1. The product showed a maximum adsorption of 85 μmol·g^-1 for chloramphenicol.Linear equation was obtained by Scatchard analysis， which illustrated that there were homogeneous selectivity adsorption sites on the surface of MIPs and its maximum apparent adsorption was 529.42 μmol·g^-1.关键词：Molecularly Imprinted Polymer;Precipitation Polymerization;Water-containing Medium;Chloramphenicol;Adsorption Characteristics
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发布时间：2023-11-14 - 摘要：Abstract:Two novel cell immobilization supports, Zr(Ⅳ)-and Fe(Ⅲ)-loaded collagen fibers (ZICF, FICF), were prepared by loading Zr(Ⅳ) and Fe(Ⅲ) on collagen fiber. As an experimental model, the immobilization behaviors of Saccharomyces cerevisiae(S. cerevisiae) cells on ZICF and FICF were characterized, and consequently, the fermentation activity of the immobilized cells were investigated. The amount of cells immobilized on ZICF and FICF reached 6.68×10^7 and 5.44×10^7 cfu/g, respectively, when the immobilizing reaction was carried out by using 3.6×10^5 cfu/mL of S.cerevisiaecells at pH 6.0 and 30 ℃. Environmental pH did not substantially affect the immobilization of S. cerevisiae on ZICF. A maximal immobilization amount was achieved in 0.1 mol/L of NaCl solution by using the cells growing at stability phase. The immobilization (adsorption) equilibrium of ZICF to S. cerevisiae cells could be described by Freundlich model, while the kinetic process followed pseudo-second-order rate model. The immobilized S. cerevisiae cells on ZICF exhibited high ethanol productivity, yielding 9.1% (v/v) of ethanol in ethanol-fermentation culture medium containing 15% of glucose. In addition, the ethanol yield kept at 7.8% (v/v) even at 12th fermentation cycle, showing an excellent reusability of the immobilized S. cerevisiae cells.关键词：collegan fiber;metal ion;S. cerevisiae-cell;immobilization support;ethanol-fermentation
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发布时间：2023-11-14 - 摘要：Abstract:Using the metastable equilibrium solubilities data of the ternary systems at 298 K, the single salt parameters and mixing ion-interaction parameters of Pitzer’s equation were fitted by multiple linear regression method. The solubilities of metastable phase equilibrium of the quaternary system KK^+/Cl^-，CO(3)^(2-)，B(4)O(7)^(2-)–H(2)O at 298 K were calculated by Pitzer’s equation. The results showed that the calculated value has a good agreement with the measured data.关键词：metastable equilibrium;Pitzer’s theory;zhabuye salt-lake;quaternary system
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发布时间：2023-11-14 - 摘要：Abstract:The influences on the stress distributions of the alveolar tissues by the different material properties of enamel and pulp were analyzed. A three-dimensional finite element model of the mandibular central incisor was constructed according to CT. The corresponding material properties were assigned to the alveolar tissues. Other two models were developed with the material properties of dentin assigned to enamel or pulp. The loads corresponding to bodily, intrusion, rotation, torque and tipping movements were applied to the three models. The von Mises stresses of the alveolar tissues of the three models were compared. The results showed that with the material properties of dentin assigned to enamel and pulp, the maximum stress differences of the roots were 21.43% and 9.25%, respectively; however the stresses of periodontal membrane and alveolar bone were hardly changed. When the stress distributions of teeth were studied, enamel and pulp should be modeled and assigned by the corresponding material properties.关键词：enamel;pulp;material properties;three-dimensional finite element model;stress distribution
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发布时间：2023-11-14 - 摘要：Abstract:The dental zirconia-leucite porcelain powder was synthesized in-situ by high temperature solid-state method using potassium feldspar, potassium carbonate and zirconium oxide as raw materials. The mechanical properties and coefficient of thermal expansion of porcelain powder were tested. The experimental results showed that the bending strength, the fracture toughness and the intensity of metal-ceramic integrated of porcelain powder prepared by the in-situ synthesis method were much better than those prepared by the indirect synthesis method, reached 105.3 MPa, 3.3 MPa /m1/2 and 42.1 MPa, respectively. There were two kinds of crystalline phases existing in the porcelain powder, zirconium oxide and leucite, which would not only be good for increasing the mechanical property, but also contribute to adjusting the expansion coefficient of the ceramic material to match for Ni-Cr dental alloys.
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发布时间：2023-11-14 - 摘要：Abstract: A methodology based upon shear-lag model was developed to derive stress profiles for any configuration of breaks in continuous fiber-reinforced metal matrix composites (MMCf), including the effect of local plasticity of matrix properties and interface characters between fiber and matrix. The importance of the matrix axial stiffness had been taken into account. An influence function superimposition technique was introduced to characterize nonlinear deformation coupling multiple damages events. It was shown that the theoretical values of the method presented in this paper were well fit with experimental results.关键词：metal matrix composite;multiple damages;stress profiles;shear-lag model
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发布时间：2023-11-14 - 摘要：Abstract:The durability of Prestressed High-strength Concrete (PHC) pipe pile is affected by the corrosion resistance of their metal ends, which depends on the material of end plate (EP), apron (AP) and pretensioned PC steel bar (PC). There are three kinds of EPs: cast steel, cold-bended steel and Q235A steel, which are widely used in pratical engineering. Their electrochemical corrosion behaviors in four typical simulated soil solutions including chloride salt soil, salina soil, neutral meadow soil and acid soil were investigated by natural immersion tests and electrochemical measurement techniqus. The results show that the corrosion rate of three kinds of EPs is smaller than that of PC and AP. The corrosion of PC and AP accelerated by cast steel EP is smaller than that by cold-bended steel and Q235A steel; but the corrosion resistance of cast steel EP is poor. There is contact galvanic corrosion between EP and AP, EP and PC in simulated soil solutions. In couple of EP/AP, AP is anode. Cast steel EP is anode when the galvanic couple of cast steel EP/ PC was in saline soil. In galvanic couples of cold-bended steel EP/PC and Q235A steel EP/PC, PC is anode. Contact corrosion quickens the damage of thin-walled AP and small-area PC, leading the premature failure of prestress. The corrosion of the existing metal ends in pratical engineering should be improved.关键词：piles;metal;electrochemical corrosion;soil
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发布时间：2023-11-14 - 摘要：Abstract:To investigate the effect of purity on damping capacity of FeMn alloy, the damping capacities of two alloys with different impurity content were measured using reversal torsion pendulum. The stacking fault probability and volume fraction of ε-martensite were determined using XRD and the microstructure was observed using OLYMPUS microscope. The results indicated that the damping capacity of the two alloys increased linearly with increasing strain amplitude. Impurity element content had great influence on the damping capacity of FeMn alloy. Compared with alloy 1(the impurity element content was 0.235%), the damping capacity of alloy 2(the impurity element content was 0.722%) decreased by nearly 20% when the strain amplitude was 4.5×10-4. It was because that the weak pinning points on Shockley partial dislocations increased with increasing impurity content, and the movement of Shockley partial dislocations became more difficult.关键词：FeMn alloy;damping alloy;damping capacity;Shockley partial dislocation
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发布时间：2023-11-14 - 摘要：Abstract:Aiming at conquering the insufficiency that AdaBoost algorithm is only suitable to the unstable learning algorithm, the method of adjusting sample center with its weight was given based on the idea that adding new classifiers is always to reduce the training error of the ensemble classifier. By this method, AdaBoost algorithm could be generalized to be several new ensemble learning methods by combining some stable learning algorithms, such as the one of dynamically adjusting the centers of sample attributes, the one of classifying by weighted distance measurement, and the one of dynamically combining sample attributes. Therefore, the application scope of AdaBoost algorithm was greatly expanded. Different from that the combination coefficients and the adjustment strategy of sample weights in AdaBoost algorithm are indirectly set to reduce the training error, the direct goal-oriented ensemble learning algorithm was given. The experimental analysis on UCI dataset proves that the generalized AdaBoost algorithms are effective and some of them perform better than the ordinary AdaBoost algorithm.关键词：ensemble learning;AdaBoost;classification combination;weak learning theorem
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发布时间：2023-11-14 - 摘要：Abstract: At present, many domestic and international researches of network system survivability mainly focused on theoretical research, and the status of complex network system are studied by use of the classical mathematical theory. In fact, the network system status has the uncertainty, randomness and so on. In this paper, taking the survivability of trusted network as the background, the key issues of network survivability are researched. Taking into account the uncertainty, randomness of network system, by introducing cloud model and deterministic finite automaton, the network system status are descript and detected in this paper. Based on cloud model, this paper proposed the network system status’ assessment and forecast model, and the associated theory analysis and confirmation are given. Finally, the feasibility and reasonableness of this model is further confirmed by the aid of simulation experiments. At the same time, this model proposed in this paper enlightened also a new way for study on the survivability of current complex network system.关键词：cloud model;Network System;Deterministic Finite Automaton (DFA);State assessment;Forecast Model
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发布时间：2023-11-14 - 摘要：Abstract:Random number and pseudo-random number can not be verified without seed key, which restricts its application in electronic commerce. Based on Interpolating polynomial over finite field, a scheme for generating verifiable random number is proposed. The scheme eliminates the error which is inevitable for interpolating polynomial over real number field. A multi-level structure is designed to accommodate huge number participants. Even if the number of participants increases exponentially, the computational time only rises lineally, which make it suitable for mobile users.关键词：random number, verifiable random number, interpolating polynomial, finite field
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发布时间：2023-11-14 - 摘要：Abstract:Blind image restoration (BIR) is a hot subject in image processing but hard to be applied due to its slow speed. To achieve real-time BIR, a new concept called the “mid-frequency region (MR)” of an image was proposed, which can be used to estimate the point spread function (PSF) and restore the image rapidly and precisely. In order to locate the MR effectively, a geometrical method without any parameters and special smoothing methods were proposed. And new MR-based Wiener filtering was derived to accomplish BIR quickly, too. Then, using the class G PSFs which fit numerous imaging systems, a new algorithm for real-time BIR was derived with the MR-based method and single-parameter derivative fitting, which was also accelerated with a fast method of smoothing. Experiments prove that the algorithm is speedy, stable, few-parameter and multifunctional, and can accomplish image deblurring, detail enhancement and noise suppression for real-time images.关键词：blind image restoration;blind deconvolution;real time;point spread functions;Wiener filtering
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发布时间：2023-11-14 - 摘要：Abstract:In order to improve performance of sweep coverage, a novel sweep coverage approach with two-tier architecture named MASC (Mobile-Assisted Sweep Coverage) was proposed by using mobile assisted carriers to help data delivery. In the first tier of MASC, mobile sensor nodes were attached to POIs for information gathering. Mobile-assisted carriers were introduced in the second tier to transfer data from mobile sensor nodes to sink node. Simulation results showed that MASC achieves better performance than existing approaches.关键词：wireless sensor networks;Coverage Approach;Sweep Coverage;Mobile-assisted carriers
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发布时间：2023-11-14 - 摘要：Abstract: Digital Elevation Model is the foundation to analyze terrain in Geographic Information System. When processing the lost sampled points, the traditional spatial interpolation methods are ineffective and impersonal in selection the interpolation function, structures as well as its parameters. This paper applies the technology of Gene Expression Programming to generation of Digital Elevation Model. The contributions include: (1)formalizing the concepts of elevation gene, buffer and cluster, etc.; (2)proving the Depth Theorem and its lemmas; (3)proposing BS strategy, timely introducing good terrain individuals; (4)proposing the algorithms of DCSA, SCPD and ESDA to dynamically search cluster by direction and avoid computing the redundant points; proposing EF-GEP algorithm. The interpolation space is subdivided and the fitting space is reduced. (5)the experiments show that the average generation is 227, the average top fitness is 97.4527 and increased by 7.23%; 3-D Geological model visually express the configuration of geologic body.关键词：gene expression programming;Digital Elevation Model;Cluster;3-D Geological Model
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发布时间：2023-11-14 - 摘要：Abstract:Finding MD5 collision messages is a important research issue.Since Pro Wang proposes the differential attack algorithm, the algorithm is attracted more and more attention.However, Pro Wang donot give the way how to get difference and differential path.This paper provides the automatic algorithm to construct difference and differential path in MD5.We can not only get Wang’s differential path and sufficient condition, but also better ones.关键词：MD5;SHA-1;Hash functions;differential attack;tunnel technique;multi-message modification method
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发布时间：2023-11-14 - 摘要：Abstract:Arriving Aircrafts Scheduling within reason in a traffic jam is one of the prevalent methods in air traffic flow management. Aiming at serious flight delays caused by increasing air traffic demands, this paper presents an Arriving Aircrafts Scheduling Model Based on Push-back and Swap. First, considering to make full use of vacancy between aircrafts and reduce delay, the Push-back method is introduced; Second, the model uses the delay factor and the cumulate arrival factor to define the swap rule, and provides two parameters to accommodate the influence of total delay time and total cumulate arrival time; The simulation and true data of flight plan was used to test the model many times and to confirm the optimization result of the push-back factors and parameters. Compared with the FCFS, the results validate the flexibility and optimization of this model.关键词：air traffic flow management;arriving air scheduling;total delay time;total cumulate arrival time
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发布时间：2023-11-14 - 摘要：Abstract:Relay system has much lower rate than that of optics and thus makes it the bottle-neck of the Internet gradually. And the load balanced switch architecture, because of its unique O(1) complexity of the connection pattern of crossbar, becomes the ideal switch architecture for high-speed switching. However, load balanced switch may cause packets to be out-of-sequence and current solutions have poor performance or higher complexity than O(1) which reduces the performance while maintaining wire-speed switching. Based on current situation, this paper introduces a load balanced switching architecture called SLBA (Smart Load Balanced switch Architecture), which uses the reverse communication mode of crossbar and the smart RB(Re-sequencing Buffer) to enable packets to be delivered into the DQ(Departure Queue) without disordering. SLBA has O(1) computational complexity throughout the whole switching process and the performance is better in light loaded condition compared with ByteFocal.关键词：packet switching;load balancing;computational complexity;order maintaining
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发布时间：2023-11-14 - 摘要：Abstract:How to concretely measure and explicitly reduce the interference of the entire network becomes a major challenge. A new protocol interference model is presented as a measure to describe the interference of the entire network in this paper. Furthermore we propose a distributed interference-avoidance topology control approximation algorithm, referred to as the ISPT. The algorithm minimizes the interference in the network according to our metrics while preserving the connectivity of the resulting topology. The simulation results show that ISPT decreases interference and improves network capacity in terms of throughput.关键词：Ad hoc networks;topology control;interference;throughput
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发布时间：2023-11-14 - 摘要：Abstract:According to non-stationary characteristic of Electrocardiogram(ECG) signal, a new method combined non-stationary signal processing and nonlinear estimation was proposed to extract the Fetal ECG(FECG) signal from the abdominal composite signal of the pregnant woman. The non-stationary Maternal ECG(MECG) signal was firstly decomposed into finite Intrinsic Mode Functions(IMFs) and one residue utilizing Empirical Mode Decomposition(EMD). The MECG component in the abdominal composite signal was a nonlinear transformation of the MECG signal and Least Squares Support Vector Machine(LSSVM) was used to fitting the nonlinear transformation. An optimal estimation of the MECG component in the abdominal composite signal was obtained by the finite IMFs and one residue undergoing the nonlinear transformation. The FECG was extracted by removing the optimal estimation of the MECG component from the abdominal composite signal. To evaluate the performance of FECG extraction method, eigenvalue analysis and cross correlation was used to estimate the Signal-to-Noise(SNR) ratio for an ensemble of FECG waveforms. The experimental results show that the clear FECG can be extracted even under the condition of the fetal QRS wave being entirely overlapped with the maternal QRS wave in the abdominal composite signal and its SNR ratio was significantly increased compared with traditional methods. The experimental results verify the proposed method.关键词：Fetal Electrocardiogram (FECG) signal, Empirical Mode Decomposition (EMD), Least Squares Support Vector Machine (LSSVM)
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发布时间：2023-11-14 - 摘要：Abstract:The rolling contact geometrical parameters and creepages of JM3 wheelset and 60kg/m rail track in static rolling contact were analyzed under different track structural parameters. On the basis of the contact geometrical parameters and creepages of wheel-rail, the effects of track parameters wheel/rail contact patch behavior were investigated using the rolling contact theory of three-dimensional elastic bodies with non-Hertz form and numerical program of CONTACT. The numerical results indicate that the rolling contact behavior of wheel/rail is not achieving the optimal state when the rail base slope is 1/40. So, it is suggested that the profile of wheel/rail tread is optimized. The rail gauge has obvious effect on contact geometrical parameters and creepages of wheel/rail. Considering the operational safety of rolling stock, the rail gauge can be increased properly under small curve radius condition.关键词：wheel-rail;Track parameters;Contact geometrical parameter;Creepages;Slippage
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发布时间：2023-11-14 - 摘要：Abstract:Based on the physical processes of solute diffusion and interfacial energy, a model of describing crystal growth was developed with the improvement of algorithm of solute redistribution and the improved discretization scheme of partial derivative of liquid concentration at the interface, including the effects of constitutional undercooling, curvature undercooling, anisotropy of interfacial energy and perturbation on the interface. By using this model, cellular automata method was adopted to simulate morphology evolution of the three typical interface including planar, cellular and dendritic in aluminum alloy directional solidification. By comparing the simulation parameters and results in this model with in the classical solidification theory, it was discovered that the planar interface was formed when the G/V value was slightly smaller than the critical value given by constitutional undercooling criterion. The variation relationship of the average primary dendrite spacing with the temperature gradient and the drawing velocity were studied and matched well with the theoretical results.关键词：directional solidification;cellular automata;numerical simulation;microstructure
- 2818
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- 30
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- 0
发布时间：2023-11-14 - 摘要：Abstract:Based on the multi-body system kinematics theory, the error modeling of three-axis simulation turntable is established, and the basic kinematics law of the turntable with error is discussed. According to the structure and principle of turntable, all the turntable assembling errors’ effects on the orientation error and position error of the turntable are analyzed in detail. With the computer simulation, the influence of all error factors on the precision of the turntable’s orientation and location is compared. These researches also can offer reference to error allocation and error probability of the simulation experiment to improve the experimental accuracy.关键词：simulation turntable;multi-body system;error modeling;assembling error
- 2979
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- 6
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- 4
发布时间：2023-11-14 - 摘要：Abstract:In order to improve the ability of flaws identification in ultrasonic testing, a flaw-recognition model based on Probabilistic Support Vector Machine, combined with Empirical Mode Decomposition and Dempster-Shafer Evidence Theory, was proposed to test on a large rotor with multi-ultrasonic sensors. Firstly, the characters of test signal were extracted with theory of Empirical Mode Decomposition. Secondly, a step forward was added to the output of the SVM classifiers to choose the category with a maximal posteriori probability, thus, an algorithm model of Probabilistic Support Vector Machine was presented. The outputs of Probabilistic Support Vector Machine were just the support degree of ultrasonic flaws. Lastly, the results of ultrasonic defects recognition were obtained with Dempster-Shafer evidence theory. Results showed that the proposed model in this paper overcame the limitation that the outputs of the traditional support vector machines were un-calibrated and should not be used to determine the category when a multi-class problem was presented. Comparison demonstrated that this model had a better performance in improving the recognition accuracy and nicety ratio of defects identification than the model of NN combined with DS and the model of SVM with odd sensor.关键词：PSVM;flaws recognition;DS evidence theory;EMD
- 2885
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- 8
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- 3
发布时间：2023-11-14 - 摘要：Abstract:In order to fix a Power tower climbing robot on a tower reliably, a novel double -V-clamper is proposed in the paper. The gripping claw has an angle fixed V-groove and a variable length, so that it is possible to clamp angle bars with various specifications in different directions. The CAD and mathematical model of the clamping mechanism were suggested and the clamping force was simulated. Furthermore，Prototype experiments were made in laboratory. The results show that the gripper can grasp angle bars firmly and reliably which widths vary from 80 to 220 mm in several directions, for the three-dimensional movement of the power tower climbing robots.关键词：power tower;climbing robot;clamping mechanism;double V-shaped
- 3154
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- 14
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- 5
发布时间：2023-11-14 - 摘要：Abstract:In this paper, a parallel control method based on structure characteristic of a half vehicle suspension with six degree freedoms is presented. Based on force analysis of the sprung mass, the coupling quantitative relation of the front and rear quarter suspensions is deduced and a hierarchical model is founded. Then a hierarchical vibration control algorithm is constructed. The vertical and pitch accelerations of the suspension center are treated as central control objects. The Hinfinite and Linear Quadric Gaussian control strategy is respectively adopted by two local controls formed by the front and rear quarter suspensions and harmonized by central control. The simulation results under MATLAB environment show that the computation time of control procedure is shortened compared to traditonal model. Thus exhaustive control could be realized according to road excitation so as to improve ride quality.
- 2553
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- 8
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- 1
发布时间：2023-11-14
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