最新刊期
卷 42 ， 期 2 ， 2010
- 摘要：Abstract:Water Rights Analysis Package (WRAP) was applied to simulate and forecast the water resources utilization and management in Tong Zhou of Beijing with the relevant data from 1956 to 2007 of this district. The results obtained from WRAP showed that: During the simulation period from 1956 to 2007, the annually natural runoff remained almost the same for the general trend and the annually regulated runoff had a slightly increasing trend, while both of them had an increasing annual variation; Yearly consumed runoff also stayed almost the same for the general trend, while the return flow was increasing overall; The multi year mean guarantee rate of water volume for the chosen study area was 59.9%, and water volume for industry and domestic use was increasing while water amount for agriculture was decreasing from the year of 1956.关键词：water rights;Water Rights Analysis Package (WRAP);flow;water resources management;Tongzhou district of Beijing district
- 3183
- |
- 0
- |
- 3
发布时间：2023-11-14 - 摘要：Abstract:Based on the engineering analogy, theoretical analysis,economic and technological comparison,the optimization and adjustment of the cofferdam of JinpingⅠHydropower Station was carried out.Through the study, the axis of the upstream cofferdam moved up;the structures of upstream and downstream cofferdam were optimized and adjusted ;the scheme of abutment excavation was optimized;the working duration of high slope excavation on abutment was shorten;the security risk and soil erosion during the construction were reduced,and the cofferdam and foundation pit safety was ensured during the water holding period since 2007.After the optimization and adjustment of cofferdam,10% of the investment is saved, 15% of the construction period is limited.关键词：JinpingⅠ Hydropower Station;cofferdam;optimize;adjust
- 2683
- |
- 0
- |
- 1
发布时间：2023-11-14 - 摘要：Abstract:A new type of stepped spillway with the plane layout similar to alphabet “V” was put forward. Numerical investigations were performed both for this type of stepped spillway and traditional stepped spillway. The results showed that the vortex range on the steps of “V”-type stepped spillway is smaller than that of traditional stepped spillway; for “V”-type stepped spillway, there is no vortex found in the symmetry wall and the flow on steps is three dimensional; the region of negative pressure is smaller than that of traditional stepped spillway, and on the same condition, the dissipation rate of “V”-type stepped spillway is higher than that of traditional stepped spillway.关键词：step;spillway;numerical simulation;Energy dissipation
- 3339
- |
- 0
- |
- 7
发布时间：2023-11-14 - 摘要：Abstract:In order to establish the relations between different scale rainfall fields, a space-time multifractal analysis on Doppler radar rainfall from HUBEX was proposed and scaling anisotropy parameters were estimated by spectral analysis. The results indicated that space-time rainfall can be considered to be a self-similar multifractal process approximately.The advection velocities of rainfall fields estimated through tracking techniques were adopted to rescale the time dimension to space dimension.The log-Poisson distribution with two parameters was used as stochastic cascade generator,and the multifractal rainfall space-time downscaling model was developed based on stochastic cascade.The relations between parameters of the log-Poisson distribution and rainfall intensity on larger scale and the coefficient of variation of rainfall fields was studied, and the characteristics of simulated rainfall fields through downscaling model was compared with the radar observed rainfall fields. The results showed that the simulated rainfall fields match scaling behaviors and preserve characteristic properties very well with those for the observed rainfall fields.关键词：rainfall;downscaling;scaling;multifractal;stochastic cascade
- 3040
- |
- 0
- |
- 3
发布时间：2023-11-14 - 摘要：Abstract:In order to supply a gap of Tennant method on salience seasonal flux rivers, the representative year flux was used to replace the multi-year average flux to improve the Tennant method.The method of choosing representative year and percentage were provided. The improved Tennant method was applied to the stations of Yellow River downriver reaches. The result indicated that the improved Tennant method embody the flux seasonal character of rivers in China North. The eco-environmental flux criterion contains all flux levels of the stations, therefore the improved Tennant is able to estimate the eco-environmental water requirement of the stations. The study provided a new and rational method for deciding the ecological water requirement quantity of the stations in the lower reaches of Yellow Rivers.关键词：Tennant method;seasonal river;representative year flux;ecological water requirement
- 3535
- |
- 8
- |
- 13
发布时间：2023-11-14 - 摘要：Abstract:In order to determine the optimal proportion of magnesium phosphate cement-based binder (MPB), influences of setting adjusting agent, ratio of phosphate to magnesia, ratio of binder to sand, and addition of fly ash on the setting time and strength development of MPB paste and mortar was studied. The compatibility between MPB and traditional concrete and the hardening mechanism of MPB were also investigated. The results showed that the setting time of MPB can be regulated to 15～30 minutes by the addition of 10% of setting adjusting agent. When the ratio of phosphate to magnesia is 1∶2, MPB paste presents the best strength, with compressive strength greater than 40 MPa at 3 hours and 50 MPa at 1 day. When the ratio of MPB binder to sand is 1∶1.5, the MPB mortar reaches the highest strength, with compressive strength beyond 50 MPa and flexural strength more than 9.1 MPa at 3 hours. When the flowability of paste is kept the same, the addition of fly ash doesn’t reduce the strength of MPB paste and the color of MPB paste is changed to be very close to traditional concrete. The main reaction product of MPB is MgNH4PO4·6H2O. There is a good compatibility between MPB and traditional concrete, therefore MPB is very suitable for rapid repairing of concrete structures undergone natural disaster.关键词：concrete construction;rapid repair;magnesium phosphate cement;mechanical properties;mechanism
- 2727
- |
- 0
- |
- 1
发布时间：2023-11-14 - 摘要：Abstract:The mechanical properties of Carbon Fiber Reinforced Polymer(CFRP) strengthened fire-damaged concrete continuous beams was tested. Four reinforced concrete T-beams were constructed. One beam was normal temperature control beam, and others were heated under ISO834 curve. One beam was fire damaged control beam, and two beams were strengthened with CFRP sheets. The same test set-up was used to loading tests of four beams. The results showed that bearing capacity, rigidity and ductility of fire damaged beams were become lower than the normal temperature beam. Ductility and rigidity of beams were dropped sharply, and the way of moment redistribution of beam changed seriously for the influence of fire. The fire-damaged beams had different failure mode compared to the normal temperature beam. External strengthening with CFRP sheets was found to increase bearing capacity and rigidity, but the ductility was dropped further. The way of strengthened position take some influence on moment redistribution of fire-damaged beam. Bearing capacity and rigidity were improved for CFRP strengthened fire-damaged continuous beams, but the drop of ductility and moment redistribution after fire should be considered.关键词：fire;concrete beams;carbon fiber;moment redistribution
- 3062
- |
- 0
- |
- 4
发布时间：2023-11-14 - 摘要：Abstract:With the effect of vehicle-bridge coupling considered, the local dynamic response in deck slabs of concrete box girder bridges was analyzed under the condition of vehicle-bridge coupling vibration. The mathematical model assumed a finite element representation of the slabs with shell elements. The vehicle simulation used a 3 dimensional linear vehicle model with 7 independent degrees of freedom. A well-known power spectral density of road pavement profiles was used to define the road surface roughness as Perfect, Good and Poor roads, respectively. Response data were produced on concrete highway bridge decks made of straight box section girder. In this way, a parametric study was conducted to analyze the effects of factors such as road surface roughness, vehicle speed, and bridge damping on the bridge dynamic amplification factors (DAFs). The analytical results suggested that the local DAFs in different locations of the slab or in the same location but made of different response vary widely. It is irrational to account for the impact effect of vehicles on the slab with a single DAF. Road roughness is the most important parameter affecting the dynamic behaviour of deck slabs. There is no critical speed or clear relationship between the DAFs and speed.关键词：vehicle bridge coupling;deck slab;local dynamic effect;concrete box girder
- 3582
- |
- 0
- |
- 2
发布时间：2023-11-14 - 摘要：Abstract:A PET biaxial geogrid is adopted to reinforce the weathered expansive marlite in XinXiang,the midline of South to North Water Transfer Project (SNWT) in China.The saturated samples of reinforced expansive soils with the size of Φ101 mm×200 mm are adopted to carry out a series consolidation and drain (CD) shear test in different confining pressure. Results shows that, the unreinforced and reinforced expansive soils are strain hardening, and curves of stress vs strain are in accord with the Duncan Chang nonlinear elastic model.The initial yield stress, the corresponding strain,and the strength of reinforced soils are enhanced,and the increase quantity is bigger with more layers of reinforced geogrid.With more confining pressure,the initial yield stress,the corresponding strain,and the strength of reinforced soils are also increased. Compared with the unreinforced expansive soils,the adhesion and friction angle of reinforced soils are both heightened.
- 2784
- |
- 0
- |
- 3
发布时间：2023-11-14 - 摘要：Abstract:In order to study the deformation destructive pattern and influence rule of box tunnel lining structure cross the ground fissure with 30 degree, based on the background of Xi’an metro engineering and the geological environment of Xi’an ground fissure, the similar constant of box tunnel lining structure modelling experiment was designed according to the similar theory, furthermore, the parameters of model concrete, model reinforcement bar and model structure country soil were designed. Strain measurement of structure reinforcement bar and concrete, measurements of contact soil pressure and peripheral soil, convergence displacement of lining and the soil displacement on the top of model are proposed. The automatic monitor of 672 mearing points is implemented by the series of static strain tester with 60 channels and the combination of changeover switch with 10 bits. With the assist of foundation settlement test plate of Chang’an University, the hanging layer of ground fissure relative to lying layer slowly falling is realized by the slowly falling of latching jack. The activity speed and faulted quantity of ground fissure is implemented by the operation speed and distance of jack controlled by the controller.With the test design, the test challenge can be meeted, and the test target can be realized.关键词：box tunnel;metro tunnel;similar model testing;ground fissure
- 3372
- |
- 0
- |
- 2
发布时间：2023-11-14 - 摘要：Abstract:Based on the existing experimental data and overseas-related models, a convenient and practical concrete creep coefficients prediction model which has characteristics of high performance concrete with certain accuracy were proposed. A multi-factor and multi-level nonlinear influence analysis under nonstandard situation was carried out. In order to determine its influence function on concrete creep, one factor was changed while other factors were kept in the standard state. By the quantification of every influencing factor on high performance concrete creep prediction , which is characterized of easier calculation and higher accuracy, it can be avoided to collect a large number of test data and the deficiency of single factor considered on ordinary concrete creep prediction are eliminated.关键词：high performance concrete;creep coefficients;prediction model;standard state;nonstandard state
- 2965
- |
- 2
- |
- 2
发布时间：2023-11-14 - 摘要：Abstract:The full failure,of loading rock samples and concrete samples were tested and its mechanics characteristics and Acoustic Emission (AE) characteristics were studied. The curves of mechanics characteristics and AE accumulative total and AE rate of concrete and rock failure were got. And the AE features including the relationships between AE and time, AE and stress were studied. By comparing the AE characteristics between rock, their different and similar AE characteristics were pointed out. The time-consuming phenomenon was discussed to both rock samples and concrete samples whose plastic deformation is obvious when stress is close to peak value strength at the process of one time loading. It was pointed out that the AE rate of those samples which have this time-consuming phenomenon will be declined and AE quietude will also appear in this stage. But for brittle rocks, neither this time-consuming phenomenon nor AE quietude will appear. In addition, the value of the parameter of time was analyzed and summarized in AE monitoring and studying. Time parameter should be paid more attention to in AE studying despite it could be ignored in general indoor rock mechanics experiment research.
- 2653
- |
- 0
- |
- 8
发布时间：2023-11-14 - 摘要：Abstract:In the test of hydraulic model with equal Froude number, the Reynolds number is decreased, due to the reduced structure of pile group according to model scale, and the model-prototype resistance coefficient of piles is not equal. In order to solve this problem and study the drag force of water flow around piles, an experimental work was conducted in a re-circulating flow tank(30 m long,3 m wide,0.26 m deep). Results revealed the relationship between piles resistance coefficient and pile number, pile spacing and pile arrangement. Based on the experimental results and achievements of related literature, the piles resistance similarity theory was developed for the piles physical model test. Research results showed that the physical model test which considered the resistance similarity of piles can offer more accurate predictions of the water flow and sediment movement.关键词：physical model;resistance similarity;model scale;re-circulating flow tank;piles
- 3128
- |
- 0
- |
- 1
发布时间：2023-11-14 - 摘要：Abstract:Incremental dynamic analysis (IDA) curves for the structure’s equivalent elasto-plastic SDOF was calculated by the response spectra normalized method. The distribution of the structural nonlinear development along the building altitude under the different seismic were compared, when the same base shear force and base story drift angles were given by interpolation to IDA curves. The difference of IDA curves were given, which resulted from the characters of elasto-plastic spectrum and the distribution of the earthquake force along the altitude of the building. A new means of analyses for the discrete of IDA curves was presented without the using of statistics.关键词：seismic response;incremental dynamic analysis;equivalent elasto-plastic SDOF;normalized response spectra;equivalent yield strength;nonlinear analysis
- 2713
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:A new method was proposed to protect submarine pipelines. Flexible spoilers were installed under the submarine pipeline to change the flow field and pressure distribution, and reduce the pressure gradient between both sides of the pipeline, so that to decrease or prevent submarine pipeline being washed out. Pressure on the surface of the pipe, pressure gradient between both sides of the pipeline and scour under the pipelines with flexible spoilers, rigid spoilers and without spoilers were compared under unidirectional current and reversing current. Experiment results indicated that rigid spoilers increase the pressure gradient between both sides of the pipeline, increase the scour depth and range, and make the pipe suffer a down pressure, and therefore make pipelines self burying under the sandy seabed. However, they are not fit for the rocky seabed because rocky span shoulders support parts of the pipeline and prevent it sinking, fatigue failure is easy to happen due to part of the pipeline impending. leading to the seabed erosion and environmental damage. Flexible spoilers decrease the pressure gradient and the scour depth and increase the lift force so that to keep the pipe stable under unidirectional current. And the protective effects of bidirectional flexible spoilers are better. When the flexible spoilers reach a certain length, the pressure gradient is close to zero and the bottom scour almost disappears. So the effective protection for submarine pipeline can be obtained.关键词：submarine pipeline;rigid spoilers;flexible spoilers;pressure gradient;scour
- 2564
- |
- 0
- |
- 9
发布时间：2023-11-14 - 摘要：Abstract:Aiming at the velocity-pressure mixed boundary problems of Stokes flow in exterior circular region, based on the character of the function of complex variable, the natural boundary element theory and series expanded method，the Poisson integral formula and the natural integral equation were deduced. The subsection linearity element was utilized to discretize the differential problems of the natural integral equation, and then the velocity value on the pressure boundary was computed, the velocity-pressure mixed problem was transferred into velocity boundary value problem. The velocity distribution was calculated by the Poisson integral formulae. The results showed that the velocity distribution by the natural boundary element method was according to the CFD software; the dimensionality of the problem could be reduced by the natural boundary element method, and the matrices of this approach were symmetrical positive ones. When the boundary was a circle especially, the matrices would be circulant, accordingly, the calculating volume was decreased greatly.关键词：Stokes flow;mixed boundary problems;natural boundary element;natural integral equation
- 3030
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:The dislocation distribution function and the analytical expressions of tresses, displacements, and dynamic stress intensity factors of the mode I dynamic crack was studied by the method of self-similar functions. The curves of two dislocation distribution functions is given.关键词：self-similar functions;propagation crack;dynamic stress intensity factor;dislocation distribution function
- 2884
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:Phase equilibria of reciprocal quaternary system Na+,Mg2+//SO42-,B4O72- -H2O at 288K were studied by isothermal solution equilibrium method. Solubilities and densities of each single salts in the solution of reciprocal quaternary system were determined experimentally. According to the experimental data, the equilibrium phase diagram and density-composition diagram of the quaternary system were plotted. The experimental results showed that the double salt Na2SO4·MgSO4·4H2O forms in the quaternary system Na+,Mg2+//SO42-,B4O72- -H2O at 288K. The quaternary system has three invariant points F1,F2, and F3, seven univariant curves E1-F1,E2-F1,E4-F3,E5-F3,E3-F2,F1-F2,F2-F3, and five fields of crystallization [Na2SO4·MgSO4·4H2O,Na2B4O7·10H2O,Na2SO4·10H2O, MgSO4·7H2O,MgB4O7·9H2O].关键词：salt-water system;phase equilibrium;sulfate;borate;solubility
- 4
- |
- 0
- |
- 1
发布时间：2023-11-14 - 摘要：Abstract:Distilled water and tetrachloromethane, used as the working fluid, flowed through the smooth quartz glass microtube with inner diameter of 19.60 μm. The single tube and double tube methods were used to measure the pressures and temperatures of the inlet and outlet of microtube.The flow rates and flow resistances in microtube were obtained when the Reynolds number varied from 9.6 to 530 and were compared with the classical theoretical values. The investigation showed that the viscous dissipation decreased the friction factor by about 13.7%. However, the pressure drop of the inlet and outlet of microtube, the entrance effect and the electrical double layer effect (EDL effect) increased the friction factor by 16.12% and 6.84%, repectively. Moreover, the friction factor was approximately equal to those predicted by the Hagen Poiseuille in 19.6 μm if neglecting those microscale effects.关键词：quartz glass micrtoube;friction factor;viscous dissipation;entrance effect;EDL effect
- 2438
- |
- 0
- |
- 1
发布时间：2023-11-14 - 摘要：Abstract:A general direct method to separate and quantify simultaneously 15 amino acids and 2 peptides was established by capillary electrophoresis(CE). This method had a wide linear range, low relative standard deviation, high precision and perfect reproducibility. The following optimized apparatus condition was explored. A fused-silica capillary 60 cm(50 cm to detector)×50 μm i.d. was used; working voltage of +25 kV was applied; background electrolyte was prepared of phosphate(50 mmol/L, pH 12.42) buffer with addition of methanol;and hydrodynamic injection of a sample (0.5 psi) during 5 sec was used at 25 ℃ with direct UV detection by diode array detector(DAD) at 206 nm. Quantitative analysis of a mixture of amino acids and peptides in maize seedlings can be achieved perfectly in this condition.关键词：amino acids;peptides;quantitative analysis;capillary electrophoresis
- 3775
- |
- 2
- |
- 2
发布时间：2023-11-14 - 摘要：Abstract:The growth rate of iminodiacetonitrile in the continuous cooling crystallizers basically obeys ΔLlaw when the particle size is greater than 100 μm, but deviates from ΔLlaw when the particle size is smaller than 100 μm. The growth of iminodiacetonitrile in crystalline process is size-dependent. The experimental data of population density distribution is fitted by the three-parameter model, and the results show that the growth rate equation MJ-3 maybe describe the growth of iminodiacetonitrile during crystalline process.关键词：Iminodiacetonitrile;growth kinetics;continuous crystallization;cooling crystalline;size-dependent
- 3140
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:A series of low molecular weight chitosans (LMWCS) with different molecular weight and lower polydispersity were prepared by the degradation of high molecular weight chitosan with H2O2/CH3COOH and gradient ethanol solution treatment. Fourier transform infrared spectra （FTIR）and 13nuclear magnetic resonance spectroscopy (13CNMR) analysis showed that the structure of the prepared LMWCS was similar to that of original chitosan without any significant change. X-ray diffraction (XRD) measurements indicated that, with the decrease of the molecular weight, the pattern transformed from "L-2 polymorph"(original chitosan) to a mixture of "annealed polymorph" and "tendon hydrate polymorph", and finally tended to amorphous. Cell culture experiments in vitro suggested that, the prepared LMWCS, in low concentrations, promoted the proliferation of fibroblasts; however, the monomer of chitosan (D-glucosamine, GlcN) had cytotoxicity in the concentration of 1 mg/ml.关键词：low molecularweight;chitosan (LMWCS);fibroblast
- 2695
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:A novel charring agent of poly(p-ethylene terephthalamide) (PETA) was synthesized by using terephthaloyl chloride and ethylenediamine through solution polycondesation at low temperature. The effect of the intumescent flame retardant (IFR) on ABS was studied. The IFR system was comprised of PETA for carbon sources and ammonium polyphosphate (APP) for acid sources. The results showed that PETA could be effective as a charring agent, the weight of residues improved greatly with the addition of IFR. When the content of APP was 25% and PETA was 12.5%, the limiting oxygen index (LOI) value of IFR-ABS system was found to be 33, and class V-0 of UL-94 test was passed. The microstructures observed by SEM indicated that the charring agent (PETA) could promote the formation of uniform and compact intumescent charred layers in IFR-ABS system after burning.关键词：PETA;charring agent;intumescent flame retardant
- 2855
- |
- 0
- |
- 5
发布时间：2023-11-14 - 摘要：Abstract:Aiming at flue gas desulphurization gypsum(FGD) and fly ash(FA), which are two kinds of industrial wastes discharged from the power plant, the active composite mineral admixture used in the concrete was developed and studied. FGD and FA were mixed with appropriate proportion and added into the cement mortar to replace the equivalent cement. Based on some methods of active excitation, the optimal proportion of FGD and FA was researched by controlling the mortar fluidity, the early strength and the strength development law. And the action effect of FGD-FA active mineral admixture, which in the microstructure of cement based material, was researched and evaluated by Scanning Electron Microscope (SEM) experiment. The results showed that FGD and FA are mixed with the ratio of 1∶2, and added into the cement mortar to replace the 30% equivalent cement, then the FGD-FA cement mortar exhibit the good mortar fluidity and the early strength, the later strength can catch and even exceed that of the reference cement mortar. The results of SEM indicated that the activity of FA is effectively activated because of the active excitation effect of FGD and other added components, so the ettringite in harden cement paste is significantly found. Therefore, the application of FGD-FA composite mineral admixture can consume a lot of industrial wastes discharged from the power plant, and it has excellent effect of hydration and low-cost.关键词：desulphurization gypsum;fly ash;admixture;activity;hydration
- 3356
- |
- 0
- |
- 7
发布时间：2023-11-14 - 摘要：Abstract:In order to improve the shape memory effect of Fe14Mn6Si8Cr5Ni solid solution alloy, the effects of different electropulsing treatment on its microstructure and shape recovery ratio were investigated . The results showed that the shape recovery ratio of the alloy subjected to electropulsing treatment at 300 V, 1100 μf, 5 Hz for 10 times reached 55.9%, 26.2% greater than that without electropulsing treatment. In addition, it was found by metallurgical structure analysis that electropulsing treatment with great energy leaded to the decrease of thermo-induced ε-martensite and increase of austenite, and the amount of stress-induced ε-martensite in alloy following 5% tensile deformation was much more and their size was smaller. The mechanism that electropulsing treatment improved the shape memory effect of Fe14Mn6Si8Cr5Ni solid solution alloy was further discussed.关键词：electropulsing treatment;solid solution;shape memory effect (SME);shape recovery ratio
- 3207
- |
- 0
- |
- 2
发布时间：2023-11-14 - 摘要：Abstract:A novel index structure named UTR*-Tree was proposed for indexing uncertain trajectories.This index combined the dynamic and the static storage structure to manage the moving objects, which treated the constrained networks (where roads nearly keep unchanged) as the static factor and used a 2-dimensional R*-Tree to manage the moving objects. An R*-Tree and hash structure were also applied to manage the position information of moving objects, which was considered to be the dynamic operation. The index can obtain the possible historical positions of moving objects from the moving objects database as well as efficiently find the current and future possible positions of moving objects. The experimental results showed that the index outperforms the traditional UTR-Tree which is a representative index structure for uncertain trajectories;The performance of node maintenance is improved by one order of magnitude, and the query performance is increased by about 25% on average.关键词：moving objects databases;constrained network;uncertain;trajectory;index
- 3139
- |
- 0
- |
- 1
发布时间：2023-11-14 - 摘要：Abstract:In order to make sure that the binary expansions of real algebraic numbers do not form secure pseudorandom sequences, a new algorithm was proposed to obtain the exact minimal polynomial from an approximate real algebraic number. Based on the algorithm, a new computer representation of real algebraic number was provided by using an ordered triple as an approximate real algebraic number within error controlling, the degree and the upper bound of height of its minimal polynomial. Compared with the popular three representations of real algebraic number, the binary bit operations of the new representation was consistent with that of the interval method, less than that of the sign representation, somewhat more than that of the order representation for the sparse minimal polynomial.However, the bits of the present representation was less than that of the three representations for the dense minimal polynomial. The proposed method can be used to obtain the exact factors of the polynomial via reconstruction of minimal polynomial from the approximate real algebraic number.关键词：real algebraic number;approximate computation;symbolic computation;symbolic numerical computation
- 3029
- |
- 8
- |
- 1
发布时间：2023-11-14 - 摘要：Abstract:Association studies between SNP and complex disease using statistics and machine learning methods has been faced serious curse of dimensionality in a large-scale SNP set. Reducing a large-scale SNP set to a smaller one is the key and primary problem for the association research. To solve the problem, a novel method, called Multi-group Genetic Algorithm (MGA), is proposed for rough feature selection in SNPs. Mutual information (MI) as the fitness of genetic algorithm is used to measure the association relation of SNPs to disease. Optimal SNP subsets searched by MGA method are combined to form a feature SNP set. In contrast to Maximum Entropy (ME) method, this method can reduce the number of redundant SNPs ,which have nothing to do with disease, while disease-related SNPs are retained. Experimental results on simulated datasets of SNPs show that the MGA method provides the appropriate size of SNP data for the future research, and can be employed in a middle-scale or large-scale of SNPs set.关键词：Genetic algorithm;mutual information;Single Nucleotide Polymorphisms(SNP);feature selection;machine learning
- 2652
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:Aiming at the best combination of multiple classifiers in ensemble learning algorithm, this paper improves the traditional AdaBoost algorithm. The combined classifiers are obtained by training the sample set. Using the sample to centralize the ratio of different kinds of targets can reflect prior probability of various classifiers. Through utilizing this parameter, this paper has given new combination parameter and the computation formula of vote threshold. It uses the sample weight skillfully and adds it to sample attributes for training and learning. It adopts new strategies to select base classifiers and gives prior probabilities AdaBoost algorithm of goal-oriented (GWPP AdaBoost algorithm) and the best combination of multiple classifiers. We have made comparative analysis of the error rate and the performance of the ordinary AdaBoost algorithm，Bagging algorithm and the GWPP AdaBoost algorithm based on the UCI datasets. Experiments show the validity of the GWPP AdaBoost algorithms.关键词：ensemble learning;AdaBoost algorithm;combination of classifiers;prior probability
- 2770
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:To select the leaders of public opinion in web BBS, who greatly influenced the direction of public opinion in Internet, the characteristics of the participators in web topic discussion were analyzed to build a model. An attribute matrix of the leaders was established based on their characteristics, such as eloquence, impact, activity and insistence. The grades of the characteristics reflected the leadership distinctly. Then, the synthetical evaluation and sort-order algorithm of the leaders in the model were given. An instance was presented to demonstrate the use of the model, including the steps and calculation.关键词：public opinion;opinion leader;attribute matrix
- 22199
- |
- 2
- |
- 8
发布时间：2023-11-14 - 摘要：Abstract:For the realistic demand of data security communications,a new security communication method was proposed. First of all，the encryption factor was extracted from the plaintext. Secondly, Encryption factor as a key group was expanded by the way of the m-sequence and generates pseudo-random key sequence that can be used to encrypt data. Pseudo-random key sequence generated in this way had good characteristics of self-correlation and the encrypted data had a better anti-attack performance. Meanwhile, the receiver can also use encryption factor to identify the integrity of the data.关键词：negative selection algorithm;encryption factor;pseudo-random sequence;encryption;decryption
- 2065
- |
- 4
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:The existing one-time password authentication technology was analyzed. To overcome its limitations on B/S application mode,a soft input model based on double random input unit was put forward. When the user need to input authentication password, the authentication server dynamically generates double random input soft keyboard, the interface layout of soft keyboard generated by the authentication server each time is random, and its interface to the corresponding input character is also random. The study results showed that based on this method, the password entered in client and password transmitted over the network are mapped to several groups of different random string each time without any computing in client, and effectively solves some password authentication problems including the capture/replay attack, memory and input intercepted assault.关键词：double random soft input model;soft input interface unit;soft control interface unit;soft logic input unit;one-time password;authentication
- 2442
- |
- 0
- |
- 5
发布时间：2023-11-14 - 摘要：Abstract:A nonnegative constrained principal component analysis method was proposed to construct a low-dimensional space by which the conversion between it and the multi-spectral space could be achieved.This method overcame the shortcoming that the reconstructed spectral reflectance may be negative when using the classic principal component analysis (PCA) to reduce the dimension of the multi-spectral image data. The reason behind the negative data produced by the PCA was analyzed firstly. According to this, a nonnegative constraint was imposed on the classic principal component analysis model and an iteration equation was constructed. Then through solving that equation, a set of nonnegative linear independence weight vectors of principal components was obtained, by which a low-dimensional spectral space was spanned. Finally a nonlinear optimization technique was used to determine the projection vectors of the multi-spectral image data in the constructed space. Experiments showed that comparing with the classic PCA, the new method can make the reconstructed spectral reflectance data in the interval of [0, 1], which maintains the physical significance of the spectral reflectance. The precision of the space founded by the new method is almost equivalent to that by classic PCA.关键词：spectral color management;nonnegative constrained principal component analysis;low-dimensional spectral space;nonlinear optimization;multi-spectral images
- 2870
- |
- 0
- |
- 3
发布时间：2023-11-14 - 摘要：Abstract:In order to understand the complexity of cellular signaling pathways as nonlinear autonomous systems, their regulation mechanisms and robustness properties, the system dynamic characteristics of cellular networks were analyzed using perspectives of engineering and information sciences. Taking the NF-κB signaling transduction networks as an example, dynamic sensitivity analysis, nonlinear dynamic analysis were explored to study the parametric sensitivities and oscillation patterns with respect to the system output of cell signal transduction networks. The simulation results demonstrated that the output signal NF-κBn is relatively sensitive to eight key rate constants and the oscillation behavior of NF-κBn is obviously affected by the negative feedback function of IKK.关键词：signal transduction networks;dynamic sensitivity analysis;oscillation;limit cycle;negative feedback
- 2295
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:In order to improve the learning performance and generalization ability of the least squares support vector machine (LSSVM), Chaos particle swarm optimization algorithm (CPSO) combined with k-fold cross validation (CV) was proposed for selecting the optimal parameters of LSSVM. Chaotic search was introduced to PSO algorithm to generate the initial chaotic particles and chaotic interrupt was added to the particles in the motions for the selection of LSSVM parameters automatically. CV error was used to construct the fitness function of particles as the assessing criteria of the LSSVM parameters choice. Gyroscope random drift was the main factors affecting the reliability of the gyroscope performance. LSSVM regression model based on CPSO-CV algorithm was used to establish time series prediction model of gyroscopes random drift for gyroscope failure trend prediction. The results showed that the proposed method is an effective approach for LSSVM parameter selection and the regression model has a better prediction precision.关键词：least squares support vector machine;chaos particle swarm optimization algorithm;cross validation;gyroscope;failure trend prediction
- 2880
- |
- 0
- |
- 3
发布时间：2023-11-14 - 摘要：Abstract:In order to generate hyperchaotic signal, a class of hyperchaotic system circuits was realized by simply adding an integration circuit to a three-dimensional chaotic Lü system circuit. The hyperchaotic attractors along with chaotic, periodic and quasi-periodic attractors of these systems were obtained from circuit simulations. The corresponding continuous autonomous dissipative system equations were investigated theoretically and simulated numerically to verify the hyperchaotic and dynamical behaviors of the proposed hyperchaotic system circuits. The proposed hyperchaotic system circuits are easy to realize by adding only a few components, thus it may find practical applications.关键词：hyperchaos circuit;attractor;system equations;dynamical behaviors
- 3774
- |
- 0
- |
- 3
发布时间：2023-11-14 - 摘要：Abstract:Aiming at the problem that the restrictive bandwidth of the charge pump phase locked loop is restrictive, the self-biased charge pump phase locked loop with adaptive bandwidth whose bandwidth was modified dynamically according to the loop state was proposed. The maximal available bandwidth was proportional to the reference frequency and the restrain of the minimal reference frequency on the loop bandwidth was eliminated. The bandwidth was immune to the variation of the process, voltage and temperature. The loop bandwidth was modified according to the state of the loop, the noise of the output was reduced and the locking speed was improved. The standard of 0.18μm 1.8 V 1P6M CMOS logic process with N trap was used and the layout was 0.048 mm2. Experiment showed that the relative peak-peak jitter was less than 1.6 ％ when the reference frequency was from 2.8 MHz to 26.6 MHz. The power was less than 20 mW when the variations of process, voltage and temperature were less than 2.1 ％.关键词：self-biased;adaptive bandwidth;Saturated PFD;Charge Pump PLL
- 2939
- |
- 0
- |
- 2
发布时间：2023-11-14 - 摘要：Abstract:In order to overcome the complexity of green product manufacturing process，a combination evaluation model based on green product fundamental property, economy, resource, energy, environment and the sustainability was proposed for green product manufacturing process. The model presented the evaluation indexes and the framework of green product manufacturing process. After quantitative analysis of the assessment indexes, it used the attribute hierachical model method, entropy method and a combined evaluation model to evaluate the green product manufacturing process strategy. Finally, an example was provided to verity the feasibility and practicality of the combinatorial evaluation model.关键词：green manufacturing;attribute hierachical model;entropy method;least squares sense;combination evaluation
- 2185
- |
- 0
- |
- 2
发布时间：2023-11-14 - 摘要：Abstract:In order to improve the work in gability of Stewart-type parallel machine tools,a novel 5-DOF serial-parallel machine tool is proposed.The proposed mechine tool is composed of a 2-TPR/2-TPS special 4-DOF parallel mechanism in series with a rotatable component.It can provide 3 translational DOFs and 2 rotational DOFs. The structural characteristics of this machine tool was discussed.The inverse kinematics solution of this machine tool was deduced by analytical method.It was investigated indetail that how to formulate the decouplinge quation of position parameters.The shape of the work space of this machine tool was described by numerical method.The effects of the change on the structural parameterts to the workspace were studied.The analysis results showed that the structure of this machine tool is simple,the workspace of this machine tool is larger than the Stewart-type parallel machine tools,and this machine tool can machine the workpieces which have complex surfaces.At the same time,there search on the analysis of machine tool in this paper povided a theoretical basis for the further designing and investigating.关键词：serial-parallel machine tool;5 degrees-of-freedom;workspace;inverse kinematics solution
- 2586
- |
- 0
- |
- 4
发布时间：2023-11-14 - 摘要：Abstract:It was difficult and complex to choice the design parameters of the non-backlash double-roller enveloping hourglass worm for the acquisition of the best engagement performance. Aiming at this question, the formulas of contacting parameters which included induced normal curvature, lubrication angle, rotation angle and relatively entrainment velocity were derived. A new multi-object parameter optimazition method was presented using the formula of Dosen to create the optimization equation based on the rotation angle and relatively entrainment velocity. Based on its characters, the equation was solved using the genetic algorithm .The result of analysis proved that the method was effective and possible and the parameters can acquire the best engagement performance. The problem of choice the parameters was solved through the studies which provided a new method to choice the best parameters for design and manufacture the non-backlash double-roller enveloping hourglass worm.关键词：non-backlash;double-roller enveloping hourglass worm;Genetic algorithm;optimal design
- 2681
- |
- 0
- |
- 13
发布时间：2023-11-14
- Technical support is provided by Beijing Founder electronics co., LTD 京ICP备09064830号-19
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0