最新刊期
卷 41 ， 期 5 ， 2009
- 摘要：Abstract:Downscaling is necessary method of scale transformation in studying impact of climate change on regions with GCM output. Impact of precipitation variation in spatial on some hydrologic processes is prominent, for example, evaportranspiration, runoff generation and concentration, which are interrelated with underlying surface obviously. A new method, Delta-DCSI downscaling method is developed here to improve the ability of future precipitation scenarios to describe its spatial distribution in sub-grids. Its is based on the Delta method, spatial distribution of future precipitation in GCM grids is taken into account with one interpolation method of dualistic cubic surface. That is to say, precipitation of GCM output in each grid is interpolated into each meteorologic station firstly. Then, change of future precipitation relative to mean simulated value of baseline period is calculated in each station. Finally, future precipitation of each station is gotten by adding the change to its observed value in baseline period. Theoretically, spatial distribution of future precipitation by this new method should be more obvious than that gotten from Delta method. Contrasts between them showed that change of future precipitation gotten from the new method is more smooth and reasonable than that of Delta for describing of spatial variation in sub-grids is strengthened and continuity of GCM output is recurred in the new method. Conclusions of future precipitation gotten from different methods showed that the effect of new method is obvious in areas with dense meteorologic stations. And it is very different from that of the Delta method in those areas.关键词：Climate change,GCM scenarios,Downscaling,Delta method,dualistic cubic surface interpolation
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发布时间：2023-11-28 - 摘要：Abstract:The flowing fields of the arch-inverted form of plunge cushion pool and the flat-bottomed one, by the action of flood discharging of seven surface outlets, Xi Luodu high arch dam, were numerically simulated by using 3-d RNG k-ε turbulence model and rapid lid hypothesis applied in water surface. Firstly, the simulation results like the velocity at center and on both sides as well as the wall pressure were detailedly compared with those from the hydraulic experiment on the inverted-arch pool of Xiluodu, and It was proved that they were well accordant. On a basis of this, characteristics of the flowing condition, diffusion of the velocity near the wall and the wall pressure produced by both forms of the plunge cushion pool were detailly compared. The investigation showed that both had a good side and a bad one. On the impacting zone of jets, the flowing condition and the wall pressure distribution produced in the arch inverted pool were more reasonable, while there were zones of high pressure near corners to be easily damaged for the flat-bottomed. On its downstream and upstream reaches, those in the inverted were worse. The research provided a reference for the design, and had a very important signification.关键词：inverted-arch plunge cushion pool;flat bottom pool;3D RNG turbulent model;flow and pressure field
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发布时间：2023-11-28 - 摘要：Abstract:In order to predominate comprehensively the abidance situation of water quality indexes of 12 representative inspection stations of main river in Sichuan Province, and to study the scheduling trend characteristic of water qualities, the article analyzed the pollution characteristic and scheduling trend characteristic. It is first time to use the runoff curve takes a period of time to study the continuance circs of each chemical index. By analyzing the water chemical indexes of each inspection station in Sichuan Province, it show that water quality characteristic analysis reflect the water quality of each inspection station, and water quality model of the runoff curve takes a period of time can reflect the river pollution continuance status preferably and intuitionisticly. Key words: water chemical element; pollution analysis; character analysis; scheduling trend analysis; the runoff curve model takes a period of time关键词：water chemical element;pollution analysis;character analysis;scheduling trend analysis;the runoff curve model takes a period of time
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发布时间：2023-11-28 - 摘要：Abstract:Abstract According to the studies on exposure degree and equivalent size of our predecessors, start-up and sediment transport rate formula of the right in the upper reaches of the Yangtze River typical was choose. parameters A of coarse degree on typical of the river bed was further defined. Through analysis we could see that the coarse degree in time and space there are changes in laws. Coarse degree was lighter in flood season than in dry season, and it was lighter upstream than downstream. It was not changed with the grain size. The riverbed roughness was a linear trend with coarse degree. According to the limited information, the relation between coarse degreea and riverbed roughness was drawn .关键词：scour coarse Coarsening parameters coarse degree
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发布时间：2023-11-28 - 摘要：Abstract:There lies much uncertainty in the environmental hydraulics system, such as the uncertainty of the measurement data, therefore the kind of pollution source identification problem is ill-posed, especially the non-unique. The classic regularization method and the optimization method can only get the “point estimation” of the parameter, so it is hard for them to solve the problem with more uncertainty. Since the water quality model is coupled with the flow field equation(Navier-Stokes equation), the direct problem is much nonliear. In order to settle the above difficulties, for the hydrodynamics-water quality coupled model, a pollution point source identification model is advanced based on Bayesian inference. Markov chain Monte Carlo sampling method is used to get the posterior probabilty distribution of the source’s position and intensity, thus solving the uncertainty and the nonlinearity well. Computational case’s result indicates the Bayesian inference with MCMC sampling can describe and solve the pollution source identification inverse problem for the hydrodynamics-water quality coupled model better.关键词：environmental hydraulics;inverse problem;Bayesian inference;pollution source identification
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发布时间：2023-11-28 - 摘要：Abstract:The complicated fracture structure of bed rock was introduced to study the process and mechanism of propagation of fluctuating pressure due to jet impingement downstream of high dams. Applying the Monte Carlo method, the transient model of fluctuating pressure propagation within an imitated rock fracture network was established. The transient time process of pressure fluctuation within each fissure and the special distribution of the intensity of pressure fluctuation were obtained by numerical simulation. It was concluded that the transient distribution of the fluctuating pressure of any node, with typically anisotropy, was the result of the propagating, reflecting and interating of pressure waves within fissure cells. The fluctuating intensity obeyed on the normal distribution. Through the spectrum analyzing, it was verified that the fluctuating pressure of any node not only lied on the pressure forced outside to the control volume, but also were determined by the geometric and physical characters of the fissure cells which are joined with the node or reached it through other cells.关键词：fluctuating pressure;Monte Carlo method;fracture network;model of transient flow
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发布时间：2023-11-28 - 摘要：Abstract:A review was made of the methods for determination of the longitudinal dispersion coefficient in natural rivers, especially in river bends, with emphasis placed on the current situation and development trends, i.e. the theoretical formulas, the tracer experiment and the empirical formulas. The applicability of the theoretical formula based on the velocity profile and its further development by researchers at home and abroad were discussed; some new methods for calculation of the longitudinal dispersion coefficient by means of tracer experiment data, and their features were analyzed; some typical empirical formulas were summarized, and some problems which need further research are proposed.关键词：compound channels;overbank flows;velocity;bed shear
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发布时间：2023-11-28 - 摘要：Abstract:Mangjiedu deep-water bridge locates in an area where earthquakes occur quite frequently, therefore the hydrodynamic force on the piers induced by the earthquake will be considerable. A semi-analytical and semi-numerical approach for earthquake induced hydrodynamic force on elastic rectangular hollow bridge pier was developed. Based on linear radiation wave theory, the interior and exterior hydrodynamic forces on pier were got by eigen function expansion method. This method avoided solving fluid-solid model directly, and was efficient for bridge engineering. The modal analysis, spectrum analysis and transient analysis were introduced respectively and the results showed that the influence of hydrodynamic force can not be neglected for Mangjiedu bridge because the 168 meter high piers could almost all in water.关键词：deep-water bridge;seismic response;hydrodynamic force;linear radiation wave theory
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发布时间：2023-11-28 - 摘要：Abstract:Because of the uncertainty of Runoff, the year generation schedule for hydropower enterprise has some certain risks, which may influence the economic benefits of hydropower. So it has become a major concern for hydropower enterprises to evaluate the risk and the profit of the year generation schedule, and build the compromised generation schedule to maximize the profits and minimize the risks incurred. In order to resolve this problem, a new model based on runoff frequency is developed for building optimal generation schedule with risks taken into account. The probability analysis and group decision making method are used in the process of evaluating the risk and profit of the generation schedule, and the method for solving the problem is presented. At last an example is given to demonstrate the feasibility of the developed model and methods.
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发布时间：2023-11-28 - 摘要：Abstract:The applicability of compacted loess-cement used as alternation cover at landfill sites has been proposed in this paper. Laboratory tests were conducted on compacted loess soil improved by addition of cement for compressibility, contractility and permeability. Tests results showed that the plastic limit of loess-cement increased with the increasing of the content of cement, but there was contrary regular in the liquid limit and the maximum dry density. Experiment data also indicated that adding 5~10% cement into the loess had more remarkable effect in improving the compressibility and contractility of the mixture. The hydraulic conductivity values of loess-cement could be nicely able to the mark of user requirements by increasing the thickness of loess-cement layer based on the equivalent principle for the volume of flow. So compacted loess soil by addition of 5~10% cement is feasible for alternative cover at MSW landfill sites and the new scheme of cover has very high value of application and wide prospects.关键词：loess-cement;landfill;strength;permeability;contractility
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发布时间：2023-11-28 - 摘要：Abstract:Traditional frequency analysis methods, such as Pearson type III is usually based on hypothesis of probability distribution subjectively, and meanwhile, it brings larger uncertainty in the parameters estimation as well due to insufficient samples. Aiming at the shortcomings of traditional method, we proposed a method which maximizes the entropy of probability distribution based on the parameters optimization by accelerating genetic algorithm (AGA), called MEGA. Frequency analysis study of the disaster rate series from 1950 to 1990 in Heilongjiang Province shows that, the probability distribution functions obtained under the restriction of 3-order and 6-order moment can truly reflect the implicit risk level information of historical disaster samples. Comparing to the Pearson type III method and information diffusion method, results of MEGA-3 and MEGA -6 are well in accordance with the reality, and avoid subjective information in the analysis process. Annual expectation disaster rates by MEGA-3 and MEGA-6 are 2.71% and 2.61% respectively, which indicate that the flood of Heilongjiang Province is under low risk level. MEGA methods proposed in this paper have a believable and reasonable result, and they will bring a new study way into flood risk analysis.关键词：disaster rate of flood;risk analysis;frequency analysis;maximum entropy distribution;Genetic algorithm
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发布时间：2023-11-28 - 摘要：Abstract:Abstract：So far, the reliability analysis of bolted connections is mainly aiming at the connection with a single bolt. However, all of the bolted connections in actual projects are composed with more than one bolt, which reliability analysis is few or none. For this issue, this paper established a model of its reliability analysis of bending and bearing capacity which is based on the code for design of timber structures (GB5005-2003) in China, and the corresponding analysis program is compiled, with applying the improved JC method which takes the corresponding influence of mutual random variables into account. According to numerous data analysis, it is presented that reliability index of bending and bearing capacity of bolted connections. When ,the reliability index of multi-bolts connections and a single bolt connection is the same, which overall average value and coefficient of variation are 4.0023 and 0.0968; While , the overall average value and coefficient of variation of multi-bolts connections are 5.8681 and 0.1230, respectively; And when linearly changes among the range of this paper, the overall average value and coefficient of variation of multi-bolts connections are 4.15941 and 0.0893, respectively. The results presented in this paper will contribute to modify the current code for design of timber structures in China.关键词：Key words：bolted connections;bending and bearing capacity;reliability;improved JC method
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发布时间：2023-11-28 - 摘要：Abstract:The non-Gaussian features of fluctuating wind pressures on double-skin facade are systematically studied by using multi-channel measurement wind tunnel tests. Based on the wind pressure sample time series and histograms, the third and fourth order statistical moments of fluctuating wind pressures are employed to obtain a description of the non-Gaussian feature. According to the value of peak factor, the criterion of the regions with non-Gaussian features is obtained, and then the regions with non-Gaussian features on the internal facade and external facade are located, which is the corner of the internal facade. Finally, the necessity of increasing pressure’s peak factor of the regions with non-Gaussian features in structural design is put forward.关键词：double-skin facade;building with rectangular shape;non-Gaussian features;peak factor;fluctuating pressure
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发布时间：2023-11-28 - 摘要：Abstract:Using the large size improved Hopkinson pressure bar with variable cross sections, a shock compression test with three kinds strain rates was carried out for the 100 mm diameter plain concrete and polypropylene fiber reinforced concrete specimens. The dynamic compression strengths and the overall process curves for stress strain of specimens under different strain rates were obtained. The experimental results indicated that under the shock compression with high strain rateloading condition, in the initial impact process, the tenacity of polypropylene fiber of reinforced concrete is roughly same with plain concrete, but with the impact proceeing some time, the tenacity of polypropylene fiber reinforced concrete is obviously better than plain concrete. The experiment provided the reference for the polypropylene textile fiber concretes in the protection project domain and military field's application.关键词：Split Hopkinson Pressure Bar (SHPB);poypropylene fiber reinforced concrete;dynamic constive relation;tenacity;impact
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发布时间：2023-11-28 - 摘要：Abstract:To ensure the Long term durability of nuclear waste, the compressive strength, slump constant and impermeability of fiber reinforced concrete are carried out after being heated to 150 ℃. By the gradation analysis, the quantification of effects of the steel fiber(A,B), polypropylene fiber（C）and fly ash（D）on the properties of concrete were done. By postponing the time for roasting, the impermeability of the specimens, adjusted by the method of steepest ascent and steel fiber reinforced concrete and high strength concrete were tested. It is concluded that: the effect on impermeability of hybrid fiber reinforced concrete after being heated:A>C>D>B. The impermeability of roasted fiber reinforced concrete and high strength concrete would degrade obviously. The impermeability of steel fiber reinforced concrete SP 10 is better than high strength concrete SP 13 after being heated 17 days. The hybrid steel fiber(A and B) reinforced concrete is suitable to the nuclear waste container.关键词：fiber reinforced concrete;temperature action;impermeability;method of steepest ascent
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发布时间：2023-11-28 - 摘要：Abstract:A new method for determining trace-level copper ion was proposed based on flow-injection on-line preconcentration and microwave plasma torch atomic emission spectrometry. Optimized determination conditions were as follows: the volume of sample solution for preconcentration was 18 mL, the time and flow rate for the preconcentration were 9.0 min and 2.0 mL/min, respectively; the flow rate and concentration of the eluant (HCl) were 1.0 mL/min and 2.0 mol/L, respectively; the power of microwave was 110W, the flow rate of the carrier gas was 1.6L/min, the flow rate of the working gas (argon) was 0.4L/min, and the excitation wavelength was 324.8nm. Under optimized conditions, determination range of the method was 2-40 g/L(y = 41.727x-5.9883, r=0.9994), its detection limit was 1.0μg/L, relative standard diviation was 2.66% (n=11), and recovery was 96-104%. The method was without complicated operation to the sample pretreatment, its automaticity was good and sensitivity was higher. The approach has been applied successfily to the determination of Cu2+ in water-steam system at power plants.关键词：on-line preconcentration;flow injection;microwave plasma torch;atomic emission spectrometry;trace-level copper.
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发布时间：2023-11-28 - 摘要：Abstract:In this paper, all of the studies were carried out under the condition of physiological pH. The interaction between Congo red and DNA was studied by spectroscopic, electrochemical, thermodynamic and viscometry methods, using Nature red as molecular probe. Binding stoichoimetry, binding constant and the corresponding thermodynamic parameters were obtained. The results indicated that the interaction of Congo red with DNA is intercalation binding. The binding stoichoimetry of nCR:nDNA=1:1, and the binding constant is KӨ25℃=4.50×103 L/mol. The thermodynamic parameters at 25℃are ΔrHmӨ =7.04×104 J/mol, ΔrSmӨ=305.88 J/(mol•K), ΔrGmӨ =－2.08×104 J/mol respectively. Entropy is driven force.关键词：Congo red;Herring Sperm DNA;Action mode;Molecular probe
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发布时间：2023-11-28 - 摘要：Abstract:MCC complexes with casein were prepared electrochemically at 12 V. Complexes were deposited on platinum anode. The properties of products were studies by means of Solubility, nitrogen content, thermal analysis and XRD. IR spectroscopy of complexes shows that electrostatic MCC-casein complexes were formed.关键词：Electrosynthesis;Cellulose-casein complexes;polysaccharide-protein complexes
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发布时间：2023-11-28 - 摘要：Abstract:The all acrylate emulsion was prepared with hydrophilic monomer methyl methacrylate (MMA) and hydrophobic monomer butyl acrylate (BA), and the influence of the reaction temperature(T),the concentration of initiator([I])，emulsifier([E]) and the monomer ratio(fMMMA) on the particle size and its’ distribution(PSD) was investigated for semi-continuous seeded emulsion polymerization. The experimental results show that the evolvement rule of PSD is changed from narrow to wide and then returned to narrow in the whole process of polymerization. The influence of [E], [I], fMMA and T on PSD is various, PSD tends toward narrow at the same reaction time when [E] increases, [I] decreases and fMMA increases; but the influence of T on PSD is not unidirectional, PSD tends toward narrow when T is raised from 70℃ to 85℃, but when T is up to 90℃, PSD tends toward wide rapidly in nucleation stage, particle dispersion index Fmax is more than the value at 85℃, and Fmax returns to narrow slightly in later continuous polymerization stage. The particle size analysis shows that for semi-continuous seeded emulsion polymerization, the particle size increases at all time, but the PSD is narrow to wide during the nucleation stage, then becomes narrow after nucleation stage, finnally keeps a narrow dispersion.关键词：Semi-continuous emulsion polymerization;Particles size and its’ distribution;particle dispersion index
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发布时间：2023-11-28 - 摘要：Abstract: Based on the relations among the stress, final wall-thickness of thin-walled tube and the characteristics of tube material, original size, curling radius along with friction condition in a axially-compressed internal inversion process on right-angled fillet die, some analytical discriminants were established for judging if a double-layered tubular piece of aluminum alloy could be steadily formed from a certain-sized round tube via internal inversion process without interference and plastic instability of tube wall, and a method was put forward for determining the maximum and minimum usable curling radius or die fillet-radius for thin-walled tubes in the process. Analysis shows that choosing tube material with little Bauschinger effect and decreasing the friction coefficient between tube and die will help to improve the formability of tubes in the process and enlarge the usable range of curling radius. The analytical conclusions aiming at the performance of two kinds of aluminum alloy tube in the process are in good accordance with the acquirable experimental results in some references.关键词：thin-walled tube of aluminum alloy;internal inversion;fillet die;formability;discriminant
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发布时间：2023-11-28 - 摘要：Abstract:The process and theory of AZ31B magnesium alloy thin sheet incremental forming at elevated temperature was investigated by CNC machine, thermal stretch machine and metallographic microscope. The results showed that AZ31B alloy thin sheet at elevated temperature can be formed successfully by single point incremental forming. Forming limit angle increases with the increasing of temperature and initial thickness. The effect of anisotropy on AZ31B sheet incremental forming was the minimum at 250 ℃, and the quality of metal sheet was the main factor which can bring defects during the incremental forming. The technical parameters of AZ31B sheet incremental forming were as follows: initial thickness of thin sheet was 0.3~1.5 mm，the best forming temperature was 200~250 ℃, the amount of tool’s feed was 0.1~0.6 mm, the forming time was 25~30 min, and the incremental forming limiting angle was 50°~65°.关键词：magnesium alloy;heat incremental forming;anisotropy;microstructure
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发布时间：2023-11-28 - 摘要：Abstract:Polymer matrix giant magnetostrictive composites were prepared by combining Tb0.30Dy0.7Fe1.95with epoxy. The effect of epoxy content and preload stress on the magnetostriction of composites was studied using standard strain gauge technique. The results showed that the magnetostriction of the composites of V alloy∶V E-44=9∶1 was 1070×10^-6 under 1 MPa preload stress. There were very marked effect of the epoxy content and preload stress on the magnetostriction of the composites. The excessive or lesser epoxy content went against the increasing of the magnetostriction for the composites. The composites had the biggest magnetostriction when V alloy∶V E-44=7∶3. The lesser preload stress had a positive effect on the magnetostriction of the composites, and the higher preload stress had a negative effect. The composites had the biggest magnetostriction when the preload stress was 1 MPa.关键词：composites;magnetic materials;bonding;magnetostriction;pressure effects
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发布时间：2023-11-28 - 摘要：Abstract:AgOx thin films were prepared in Ag＋-triethanolamine (TEA) aqueous solutions by using chemical bath deposition method, and the UV Vis light transmittance of AgOx thin film was investigated. The results showed that low films thickness is corresponded to short time or low temperature. AgOx film thickness is thinner when it is prepared at lower temperature or in shorter time. The crystallographic phase of deposited film is a mixture of Ag, Ag2O and AgO, and the AgO content of the AgOx films varies with the change of ratio of second TEA mass to first TEA mass. The light transmittance of film increases with the increase of AgO content in the films or the reduction of the film thickness. An obvious peak in the transmission spectrum was observed at a wavelength of about 300 nm, when the AgO content increases, the peak intensity increases and the peak position will show a red shift. Another peak in the transmission spectrum was observed clearly at a wavelength of about 980 nm, the peak intensity also increases with the AgO content increasing, and the maximum light transmittance is up to 70%.关键词：chemical bath deposition;AgO;film;light transmittance
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发布时间：2023-11-28 - 摘要：Abstract:For decreasing the false alert in high flight density, we researched the position-velocity vector for aircraft pairs, and proved that only the pairs which inner product of difference vectors of position and velocity was less than zero would be in unsafe state. According to the flight rules, the pairs were be confirmed by linear prediction. Many scenarios via simulation surveillance radar data were demonstrated and the results showed that it was more useful and reliable for high flight density situation, and especially in reducing the false alert for opposite flying aircraft关键词：Air Traffic Control System, Vector Analysis,Short time Conflict Detection
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发布时间：2023-11-28 - 摘要：Abstract:Automatic path-oriented test data generation is not only a crucial problem in structural testing but a hot issue in the research area of software testing today. To investigate the feasibility of pseudo-parallel genetic algorithm’s (PPGA) application in path testing, the main idea and basic flow of automatic path-oriented test data generation using evolutionary algorithms are concluded first. Based on MATLAB7.1, a pseudo-parallel genetic algorithm and a simple genetic algorithm (SGA) using generation gap are implemented. The PPGA selects individuals for unrestricted migration based on their fitness values. Using a triangle classification program as an example, under the guidance of branch distance based fitness function, performance of generating path-oriented test data between these two algorithms are compared. Experimental results show that PPGA based approach can generate path-oriented test data more effectively and efficiently than SGA based approach does.关键词：software testing;path testing;pseudo-parallel genetic algorithm;test data generation
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发布时间：2023-11-28 - 摘要：Abstract:Abstract: In traditional Gene Expression Programming (GEP), the survival of individuals depends on their fitness, and the relationships between them are ignored. This may affect the evolution efficiency. To tackle these problems, this paper analyzes the cause of premature in GEP, introduces a Cluster-Elutriate Algorithm (CEA) based on minority-protection strategy, and develops a group of concepts, such as, β- cluster. The results of experience shows that the efficiency of GEP is improved based on GEA.关键词：cluster- elutriate Algorithm;the farthest neighbor clustering;β- cluster;individual similarity
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发布时间：2023-11-28 - 摘要：Abstract:In order to effectively authenticate several strings,a message authentication code named VHMAC was proposed,whose input can be a vector of strings.VHMAC was based on the composition of universal hash families.For efficiently processing a vector of strings,a parallel universal hash family was defined,its output was then put into another universal hash function.The security definitions of ordinary message authentication codes were extended to the vector-input scenario.Based on the assumption of the underlying block cipher as a pseudorandom permutation, the security of VHMAC was proved.Also,VHMAC was pre-processible and parallelizable.关键词：message authentication code;pseudorandom function;universal hash function
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发布时间：2023-11-28 - 摘要：Abstract:When Diverse Firewall Design was employed to configure a firewall rule set, multiple teams, who got the same requirement specification of the firewall rule set, independently configured different versions of the rule set. And then rule sets comparing algorithms could be employed to decide whether multiple rule sets were equal or not. However, the performance of the present algorithm was not very good. A rule sets comparing algorithm based on rules intersection was proposed by this paper. First, rule conflicts resolving was employed to eliminate conflicts among rule sets. And then the problem of rule sets comparing was transformed into the problem of pictures comparing in multi-dimensional space. At last, the algorithm proposed by this paper compared the areas and the color of pictures to decide the rule sets were equal or not by employing rules intersection. The results of experiments not only showed that the algorithm could find out all discrepancies among rule sets, but also verified that the performance of the algorithm was better than that of the present algorithm.关键词：rule sets;rule sets comparing;pictures comparing;firewall;rule sets correctness
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发布时间：2023-11-28 - 摘要：Abstract:The particle swarm optimization (PSO) is apt to cause premature convergence for boundary-constrained optimization problems. To solve this problem, two drawbacks in the invisible wall (IW) widely employed in PSO were discovered: the best particles in neighborhoods and the other particles have distinct opportunities to be evolved, and many updates of a particle’s position are unnecessary. An improved IW (IIW) was proposed. IIW detects whether or not a particle flies outside the allowable solution space in each dimension. If a dimension of the particle is out of the space, it will be updated immediately. Experiments were conducted in several boundary conditions and in different dimensionality, and the results showed that IIW performed more effectively than IW.关键词：particle swarm optimization;evolutionary algorithms;Swarm intelligence;invisible wall;boundary-constrained optimization
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发布时间：2023-11-28 - 摘要：Abstract:For some problems in distributed hash table (DHT), it is insufficient to show the virtue of algorithm only with the notation. The paper gives two groups of the elementary probability distribution on the discrete and continuous address spaces. With these properties, the paper analyzes two problems of the load balance and estimation of the network size in DHT, and obtains such results: the loads of nodes in Chord network are imbalanced; and Pastry adopts the half of the interval between two neighbor nodes as the managed zone, which makes great improvement on the balance; moreover the problem of estimating the size of network is equivalent to the problem of estimating the parameter of a passion process.关键词：distributed hash table (DHT), probability distribution, load balance, estimation of parameter
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发布时间：2023-11-28 - 摘要：Abstract:Due to determining the classical ranking functions of program verification, a new approach was proposed based on the theory of semi-algebraic systems. It automatically converts the problem of program verification to solve the ranking function of semi-algebraic systems. The sufficient and necessary conditions on parameters in ranking functions can be obtained using symbolic computation tool, DISCOVERER and Farkas' Lemma, and then automatically synthesized the novel ranking function by symbolic computations. The method with other methods to do a comparative is reasonable theoretically, and experimental results show that it is efficient.关键词：DISCOVERER;Farkas' Lemma;Ranking Function;Semi-Algebraic Systems;Termination of Program;program verification
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发布时间：2023-11-28 - 摘要：Abstract:In this paper, a new kind of head structure and motion mechanism were developed by integrating synthetically a crank-rocker mechanism and a head face eccenter mechanism, that realize the operating functions of LED chip die bonders to drive chip of, such as picking up, carrying and bonding. Firstly, the working process and requirements of the head assembly were analyzed, the working theory of the head mecahniam was studied, the motion parameters of the crank-rocker mechanism were designed, a head face eccenter mechanism was developed, the motion time sequence of the excutive mechanisms was discussed. Secondly, the parts and assembly of the head structure and motion mechanism were designed by using pro/Engineer, the mechanim motion models and driving models were built, the motion simulation of the head mechanism was realized by using Mechanism/pro, the simulation results were analized, the head structure and mechanism parameters were optimized. Finally, the feasibility and rationality of the designed head mechanism and its simulation models were verified by testing the physical prototype, the developed head mechanism has been used in the whole equipment successfully, the performances of whole equipment have risen significantly.关键词：semiconductor device manufacture;product development;mechanism;kinematics;head mechanism
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发布时间：2023-11-28 - 摘要：Abstract:In order to ensure the reliability of valve for nuclear power system, according to the real dimension of the safty relief valve body, the modeling for three-dimensional steady thermal-structure coupling is established considering the heat exchange between valve body and internal medium, at the same time between valve body and environment. By using the multiphysics field of the ANSYS software, the thermal-structure coupling effect of valve body is simulated with the appropriate gridding density. On this basis, by using the probabilistic design system of the ANSYS software, the structure reliability analysis of valve body is simulated, based on Monte-Carlo simulation method. The results show that the structure reliability of the valve body is enough under working circumstance. Sensitivity of the random variables on maxstress is also researched, and it is obtained that L is the most significant variable on reliability. But the design for thickness of the valve body seems to be too conservative, on the premise of ensuring reliability, the body structure can be improved by decreasing parameter L, saving material up to 52.7％and peomoting technology level of safty valve effectively.关键词：valve body gridding density thermal-structure coupling Monte-Carlo simulation method reliability
- 2658
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- 244
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- 3
发布时间：2023-11-28 - 摘要：Abstract:Abstract:The most important mission in the field of the computer vision is how to improve the precision of the camera’s scaling and how to simplify the process.For this purpose, a new method to calibrate the camera’s all the interior and exterior parameters using at least 4 directions vanishing points and 2 calibratinon points is brought forward.It only needs one image of the template which is devised in this paper.Then use Hough transform to detect lines in the image and further locate the vanishing points in each directions; use camera-calibrating equations which are brought up in the paper with the positions of the vanishing points to resolve the camera’s implicit parameters matrix; finally divide the matrix into the camera’s interior and exterior parameters according to the matrix’s characteristic and accomplish the calibration.Compared with other calibrating ways,this method is more facility and precise.关键词：camera calibration, vanishing point, Hough transform, line detection
- 4618
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- 328
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- 2
发布时间：2023-11-28 - 摘要：Abstract:Based on equations of motion of 2K-H planetary gear trains, given a determine method of self locking of hydrodynamic power split torque converter (HSTC); Put forward an analysis method of power flow of HSTC; and established the relationships between structural parameters and transmission parameters of HSTC; The transmission parameters of all kinds of HSTC such as power flow, torque ratio, power split ratio and efficiency are compared. The results of research show: if HSTC have no power circulation and self-locking, the efficiency of HSTC is higher than hydraulic torque converter, and applications of HSTC are wider than hydraulic torque converter. The study results can provide a theoretical basis for calculation and design of HSTC.关键词：hydrodynamic split torque converter;power flow;transmission efficiency;torque ratio;split ratio
- 2493
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- 212
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- 2
发布时间：2023-11-28 - 摘要：Abstract:New development of a fuel supplying system in CARDC is presented in this paper. The system uses a piston to squeeze gas fuel to the heater of pulse facilities. With very simple structure and high safety coefficient, the system achieves the purpose of controllably supplying fuel with needed amount to the heater, and also can feed fuel with constant mass flow rate in the fixed testing interval. The system has been applied successfully to the newly built pulse combustion wind tunnel with diameter of 600mm.关键词：pulse combustion wind tunnel;fuel supplying;application
- 2637
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- 198
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- 0
发布时间：2023-11-28 - 摘要：Abstract:To solve the limitation that conventional spread sptrum communication suffers from PN sources，a scheme of double Code Phase Shift Keying (CPSK) Spread Spectrum (SS) communication system was proposed,in which synchronization is achieved by synchronization code based on specia phase. In the system, information is transmissioned by orthogonal channels,and all SS codes come from one SS code by cyclic shifting.Synchronization is achieved by a same synchronization code which have the same special code phase in orthogonal channels, so a high correlative peak is produced in the synchronization process, which is easy to distinguish. The simulations demonstrated that the proposed shceme is easy to achieve synchronization and is effective in improving the utilization of system resources comparing to direct sequency spread spectrumm.关键词：spread spectrum communication;CPSK;cyclic shifting;synchronization code
- 2596
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- 220
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- 0
发布时间：2023-11-28 - 摘要：Abstract:If the effects of the local oscillator (LO) phase noise and the power amplifier nonlinearity on the digital transmitter error vector magnitude (EVM) can be predicted easily and effectively, and the bit error rate (BER) can be predicted using the EVM, a new way will be provided to estimate the performance of the modern communication systems. In order to solve this problem, the relationships between EVM and two effects, LO phase noise and power amplifier nonlinearity, were derived and expressed separately. And the third order intermodulation distortion (IMD3) was used to simplify the expression of the EVM. Then, an expression for the EVM was derived based on the digital transmitter model that considers local oscillator phase noise and power amplifier nonlinearity. Finally, the math formula of bit error rate (BER) versus EVM,which can be easier and more useful to predict BER,was given. Through the simulation, it was found that a simple way was provided by using IMD3 to calculate EVM, without considering the input power, output power, 3rd interception point and 3rd intermodulation product power. And predicting BER with the value of EVM can save the necessary closed loop equipment in the conventional method and shorten measure time.关键词：Error Vector Magnitude (EVM);Phase Noise;nonlinearity;third-order intermodulation distortion (IMD3);bit error rate(BER)
- 5429
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- 814
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发布时间：2023-11-28 - 摘要：Abstract:A adaptive acquisition algorithm, based on coherent correlation model and FFT,is presented for DS/SS navigation signal under low signal to noise ration. By this algorithm , the S/N after testing is improved and acquisition time is become shorted. The simulation results of GPS C/A signal acquisition indicated that the performance of this algorithm is better than non coherent correlation, about 2 dB gain is gotten and the signal -175 dBW at sensitivity level can be acquired. This algorithm is applicable to tracking and precise measurement of PN phase of satellite position and DS/SS ranging signals.关键词：Signal to noise ration(S/N), direct sequence spread spectrum（DS/SS）, adaptive coherent correlation, acquisition, FFT
- 2646
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- 374
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- 0
发布时间：2023-11-28 - 摘要：Abstract:To analyze the parameter estimation performance of PARAFAC decomposition under Constant Modulus (CM) constraint, Cramer Rao Bound (CRB) expressions for PARAFAC decomposition under “First Row Known” and CM constraints were proposed. The fitting algorithm, named TALS CM, was also developed. Simulation results showed that, compared to the normal PARAFAC decomposition, CM constrained PARAFAC decomposition has a lower CRB. The performance of TALS CM algorithm was close to its CRB, which implied that TALS CM is asymptotically efficient.TALS CM algorithm has better performance than traditional TALS algorithm. Utilizing CM property of source signal improved the performance of the PARAFAC based signal processing algorithms.关键词：blind signal processing,;Cramer-Rao Bound;PARAFAC;trilinear decomposition;Constant Modulus
- 2804
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- 208
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- 1
发布时间：2023-11-28 - 摘要：Abstract:To receive high dynamic and information rate user signal in near space, it is necessary to design carrier acquisition and track system. According to the high dynamic and information rate characteristics of wireless link in near space, the performance and implement scheme of carrier acquisition and track were analyzed. The design principle of carrier acquisition and track under high dynamic and information rate situation was explained and deduced clearly. A new suitable method was proposed for high dynamic and information rate wireless link.The design method of digital receiver system was described in detail under high dynamic and information rate situation.The results of experiment and comparison showed that the design method of carrier acquisition deriving from DQPSK under high dynamic and high information rate situation was available.关键词：near space;high dynamic and high information rate;acquisition;track;carrier
- 2703
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- 484
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- 0
发布时间：2023-11-28 - 摘要：Abstract:In order to improve the issues in designing fuzzy logic controllers, an intelligent control method using vector decoupled clouds model is proposed. The transformation between qualitative and quantitative knowledge is presented via qualitative control mechanism of clouds model to guarantee the transfer of linguistics’ uncertainty. With the vector decoupled control, the multi input variable of high order non linear system can be consolidated to single one. Meanwhile, the rules of clouds model controller are predigested and the stability of the closed loop is guaranteed. Finally, the vector decoupled clouds model controller is used to control ball and beam system, and the simulation results demonstrate the effectiveness of the method.关键词：vector decoupled;clouds model;intelligent control;ball and beam system
- 2337
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- 268
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- 2
发布时间：2023-11-28 - 摘要：Abstract:In order to improve the static precision for Digital Oscilloscope(DSO) and realize the automatic measurement, the chaotic measurement model based on the two dimension Henon map is adopted to measure the signal’s amplitude. By selecting model’s parameters and initial value, adjusting the chaos threshold, the high precision calibration of the signal’s amplitude is realized. Meanwhile, the measurement model with variable parameters is constructed. This way does not need judge the system’s state whether change from chaotic state to steady state, and reduce the burden of DSO greatly. This algorithm changes the traditional calibration way, which embedded in the function library of DSO as part of the calibration algorithm, and improve the calibration performance. Compared with the traditional calibration way, the experiments show that this method has good measurement result.关键词：Digital Oscilloscope;chaos;Calibration;Static Parameters;measurement
- 3054
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- 242
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- 0
发布时间：2023-11-28 - 摘要：Abstract:Aimed at overcoming the shortcoming of the current stochastic assessment of equipment sensitivity, an effective new method was proposed which use the voltage sag severity index of each type equipment as stochastic variable and search its objective probability density function based on maximum entropy principle. Then the equipment sensitivity was described by equipment failure rate through cumulative summing method. The detailed stochastic assessment principle and solution method was proposed also. The simulation results of PCs showed that compared with four current probability assessment methods,the proposed method is fit for small samples condition and has well assessment precision and good adaptability.关键词：sensitive equipment;voltage sag;sensitivity;voltage sags severity index;maximum entropy principle
- 2475
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- 196
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- 1
发布时间：2023-11-28
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