最新刊期
卷 47 ， 期 Z2 ， 2015
- 摘要：Abstract:The inartificial runoff series before building reservoir are treated as the perfect state for river ecology health, and an indexes system for assessing the approach degree between the discharge operated under one control scheme and the inartificial runoff is established. Moreover, a new comprehensive evaluation method combining fuzzy set pair analysis and entropy weight fuzzy iteration is put forward to compare six different control schemes for the discharge of Ertan reservoir. Compaired with composite fuzzy matter-element method, the best scheme determined is one, but the proposed method can not only provide the evaluation indexes weights without preference for the evaluation schemes directly, but also display the structure of uncertain relationship between evaluation scheme and grade standards in detail. The study case shows that the proposed method is feasible and effective.关键词：reservoir operation;ecological water demand;comprehensive evaluation;fuzzy set pair analysis;entropy weight;fuzzy iteration
- 1714
- |
- 12
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract: The comparing experiment of different influence factors were conducted on the basis of the conceptual model test of various large particle sediment . Thus the movement of large particle sediment were investigated by using photography technology to record the skip trajectory. The results indicated that when the water depth exceeded the critical condition, the sediment will no longer jumping. What’ more, the critical depth increased with the increase of grain diameter, the critical depth approximately equal to the grain diameter. Meanwhile, according to the characteristics of jumping pebble, under a certain grain diameter and gradient, the depth had a negative power function relationship with the saltation height and length. Whereas, under the same depth and gradient, there was a positive power function relationship between jumping height, length and particle size. Besides, when the water depth and particle size are certain, with the increase of gradient, the jumping height decreased, and the jumping length increased. In addition, the jumping length and height had a multiple relations with the particle size and all showed a negative correlations with the water depth and the grain diameter. The experimental conclusions will provide certain reference frame to the design of outlet structures.关键词：smooth and steep slope;pebble;saltation characteristics;critical condition
- 1846
- |
- 4
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract: Sediments are carried into mountain stream by debris flow. It will cause the water level of downstream rise suddenly and make a great loss of life and property. This paper aims to study the regulation of water level variation under high concentration of sediments in steep channel flow. The result reveals that the variation is related to the additional flow and resistance.
- 1665
- |
- 2
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:In order to solving the problem of the distributed non-point source pollution models difficultly applying in data scarce catchments, a case study was conducted in the XiChong river basin within XiChong County based on SWAT model combined with parameter transplant regionalization method. Verifying basin satisfactory results (R2 > 0.8, NSE > 0.5) showed runoff and sediment parameters transplantation had some applicability for SWAT. Results of study area indicated SWAT combined with runoff and sediment parameters transplantation can be used for further simulation of non-point source pollution.
- 2014
- |
- 4
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:Water temperature is an important factor affecting water environment. The unique and complex plateau climate and hydro-geomorphology would have an important impact on water temperature. In this paper, on the basis of the meteorological, hydrological and water temperature data for many years, adopted the idea of statistical data mining and analysis, used multiple linear regression model on the influencing factors analysis of the water temperature in middle reach of the Yarlung ZangBo River. The analysis results showed that, for the upstream, the main factor was meteorology, especially air temperature. As for the downstream, the main factor was the water temperature of upriver. Interannual and interdecadal changes in water temperature showed decreasing trend, but not obviously, and the warming rates from upstream to downstream increased. The water temperature rose as the altitude decreased and climate warming, but the water temperature of Nuxia Site rose slower and lower.关键词：Yarlung ZangBo River;water temperature;multiple linear regression model;meteorology;flow
- 1814
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:A series of experiments were performed in a compound channel to study the effect of floodplain vegetation on the distributions of depth-averaged velocity and bed shear stress. Velocities and bed shear stress were measured by two 3D acoustic Doppler velocimeters (ADV) and a Preston tube respectively. The results showed that an S-shaped distribution occurred in the vegetated region. The increases of discharge and plant spacing both contributed to lager value of depth-averaged velocity. It was confirmed that the bed shear stress was weakened with vegetation on the floodplain. The bed shear stress in sparse cases was increased while the ratio of bed shear stress to flow resistance was reduced compared to dense ones.关键词：compound channels;vegetation;depth-averaged velocity;bed shear stress;composite roughness
- 1636
- |
- 2
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:Drinking water safety in Sichuan Basin is an important issue. Here, Mingshan District as a typical mountainous and hilly area in the Sichuan Basin was selected as the study area. Pollution sources of drinking water and waterborne diseases therein were investigated. Health risks arising from the exposure pathway of drinking and skin contact were evaluated by adopting the USEPA Health Risk Assessment (HRA) Model. Temporal and spatial variation characteristics of health risks with support of Geographic Information System(GIS) technology. The results showed that: (1) the contents of nitrate and ammonia were exceeded the upper limit of Standards for DrinkingWater Quality (GB5749-2006) in some of the rural drinking water sources; (2) the non-carcinogenic risk of skinexposure to nitrate, nitrite and ammonia was lower than the drinking water exposure’s, and the non-carcinogenic risk of nitrogen was all within the acceptable level 1, in another word, it would not harm the residents’ health; (3) the non-carcinogenic risk of nitrate, nitrite and ammonia varied relatively greatly at time and space.关键词：drinking water sources;nitrate;health risk;temporal and spatial variation;Mingshan District
- 1415
- |
- 6
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:Theory formula of diffusion parameters of Bingham fluid based on column–hemispherical penetration grouting is not existence, such as, diffusion radius of hemispheroid, diffusion length belongs to cylinder et al, so it lag far behind the actual grouting engineering. In this study, according to combining with the rheological equation and seepage motion equation of Bingham fluid , carrying out theoretical analysis and experimental researches, theory formula of diffusion radius of hemispheroid, diffusion length belongs to cylinder based on column–hemispherical penetration grouting were deduced. Relationships between some grouting factors and them based on cylindrical penetration grouting, such as, rheology of Bingham fluid, grout pressure, groundwater pressure and w grouting pipe radius, were analyzed theoretically. What’s more, they were validated by means of designing grouting verifying experiments. Experiment results show theoretical diffusion radius of hemispheroid, diffusion length belongs to cylinder calculated by the formula of diffusion parameters of Bingham fluid based on column–hemispherical penetration grouting have about 25%--30% of the differences with the actual measurement diffusion radius by grouting experiments, but they are all within the acceptable error limits. Therefore, research achievements may not only can provide strong theoretical basis for perfecting the penetration grouting mechanism, but also play a reference guiding role for the theoretical research, design and construction on grouting technique.关键词：Bingham fluid;column–hemispherical penetration grouting;diffusion radius of hemispheroid;diffusion length belongs to cylinder
- 1550
- |
- 10
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:The stress relaxation tests of silty mudstone under triaxial compression are performed with the RLJW–2000 rock servo-controlled rheology testing machine. Based on the test results, the stationary Hooke-Kelvin model is first selected to describe the stress relaxation properties of silty mudstone. In accordance with the difference between the theoretical results of stationary model and the test results, it can be seen that large errors will be encountered without considering time-dependent behaviors of the parameters, so it is necessary to establish the non-stationary model of rocks. By constructing the relation between model parameters G2、H1 and the time, a three-dimensional non-stationary viscoelastic Hooke-kelvin model is established. Comparing the theoretical results of stationary and non-stationary models with the test results, it is shown that the non-stationary viscoelastic Hooke-kelvin model can more accurately reflect the stress relaxation properties of silty mudstone than the stationary model. The research can provide some references for the future study of the stress relaxation model of rocks.关键词：silty mudstone;stress relaxation;viscoelasticity;non-stationary Hooke-kelvin model
- 1631
- |
- 4
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:Abstract: The rationality is yet unified conclusion by using the deformation of the center or the boundary points to calculate the rock deformation parameters. According to the modulus of elasticity analytical solution of rigid circular and flexible square bearing plates at center and boundary points, this paper demonstrated the difference of deformation parameters at different parts of bearing plate; by using three-dimensional finite element simulation, this paper studied rock deformation and deformation parameters of bearing plate in stiffness condition, and comparative analyzed the difference and laws of deformation modulus and real parameters of deformation calculations of center and boundary points. Studies show that: the calculated rock deformation modulus decrease with bearing plate stiffness increasing, and more and more close to the real deformation modulus of rock mass; the surface displacement of rock mass boundary is 35% less than average surface displacement of rigid circular bearing plate; the surface displacement of corner points is 42% less than average surface displacement; finally, based on the results of this study, the field test results of bearing plate in tunnel area of Jinping Hydropower Station are fixed to improve the rationality of test parameters.关键词：Rockmass Mechanical Parameter;Bearing plate test;Elastic mechanics;numerical simulation;Correction;Reduction factor
- 1552
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:Abstract：Luojiaping landside locates in 38km upstream of the dam site of Xiangjiaba Hydropower Station and there is no deformation before water storage of xiangjiaba dam. However, obvious deformation has been found after phase-i water storage and the velocity of deformation has increased after phase-ii water storage. It is shown that a landside caused by water storage has occurred there. Detailed geological structural investigation, which based on the analysis of the monitoring data of water storage, rainfall conditions and deformation, are carried out in this paper in order to research the relationship between the curve of displacement-depth and geological characteristic. The confined water model of bedding rock landslide is put forward to explain deformation behavior. The research shows the water storage is the cause of landside, the rainfall is the motivation of landside. The groundwater level is rising during water storage, but parts of the sliding surface and soil deposits at the toe of landslide under the groundwater level caused the latter becoming soft. The resistance force then decreased due to plastic deformation and viscous. The compatibility of deformation of dangerous rock body may occur by plastic deformation. The ground cracking after landside. The confined water turns out during the rainfall and water impoundment, the heavier the rainfall the higher the pressure head will be, and the pressure is concerned at the lower part of landside. As a result of confined water and its own weight, the deformation rate and deformation size of the toe area is larger than the heel area. The landside is more dangerous in persistent rain than heavy rains.关键词：Luojiaping landside;deformation monitoring;water storage;rain;confined water;model
- 1695
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract: In order to explore the failure mechanism of saturated concrete under the pore water pressure, through theory analysis the influence of pore water pressure and porosity for the micro-crack evolution and macro-mechanical properties of concrete on the existing researches, the stress intensity factor for I, II crack of concrete and the prevailing conditions for I-II mixed crack appearing tension failure and shear failure were determined under water environment. Based on pressure gradient between sealed pore water pressure Pf and transfixion pore water pressure Pg, through “YSL-200” computer-controlled hydraulic multi-channel axial compression combined effects of rock rheological，the failure mechanism of concrete under water environment was explained from microscopic perspective. the results showed that: the microscopic failure factors mainly including the change of porosity and hydraulic gradient caused by Pf and Pg; The failure mode belongs to“X”mode shear failure under water environment; The existence of water confining pressure could improve the compressive strength of saturated concrete.关键词：pore water pressure;stress intensity factor;porosity;pressure gradient;failure mode;failure mechanism
- 1732
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:To study the crack dynamics propagation law of brittle materials,this paper used PMMA (plexiglass) as the test piece material,studying through impact experiments and Lagrange simulation algorithm coupled with SPH. Under other conditions consistency, by changing the impact velocity and the angle of initial crack test in group, than corresponds exactly to the impact experimental conditions and the test pieces state made simulation. The main conclusions are: extended form of brittle materials mainly airfoil dynamic crack extension, as well as non-airfoil secondary cracks; airfoil crack vertically downward direction, the direction of crack propagation tends secondary level; dynamic extend the length of the crack with the impact velocity exponential trend growth; specimens appear secondary cracks, to a large extent an increase of crack length; airfoil crack extension angle with increasing initial crack angle decreases; Rugby Long days and SPH coupling algorithms to realistic display dynamic crack propagation wing cracks form and so on.关键词：Dynamic crack;crack propagation;dynamic intensity factor;extended length;extension angle
- 1486
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:Abstract: Transport system has been severely destroyed during the 2008 Wenchuan Earthquake, and a great lot of bridges, especially those near the faultage, suffered severe damage and even collapsed, which led to inefficient rescue or reconstruction following the earthquake. The geomechnical similarity model test was conducted to investigate the effect of the deformation of the site nearby the fault on the damage of the simple supported girder bridge under the lateral loading. The results show that: the failure mode of the model was highly similar to that of Gaoyuan bridge and deformation of the site was mainly happened near to the fault due to fault movement; the girder falling partly attributed to the centralized deformation of the site nearby the faultand partly attributed to the nonproportional rigid between the upper structure and the ground site; and the deformation of the ground near to the fault was amplified by the fault movement during earthquake.关键词：Gaoyuan bridge;fault;geomechnical similarity model;static monotonic test;earthquake damage mechanism
- 1559
- |
- 4
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:Seismic performances of hollow brick infills with or without mortar plaster layer were investigated base on the field reconnaissance following 2008 Wenchuan Earthquake or the 2013 Lushan Earthquake。Decades of mortar specimens with different type of fiber or various percentage of fiber were designed and tested. The relationship among compressive strength of mortar, the type of fiber and the percentage of fiber was discussed. Joint shear testings to 30 different specimens were carried out, which include 3 specimens without mortar plaster layer, 3 specimens with general mortar plaster layer and 24 specimens with different fiber mortar plaster layer, in order to reveal the joint shear properties and failure mechanism of masonry with or without mortar plaster layer. The concluding remarks include that the joint shear strength of masonry without plaster layer is quite different from that with plaster layer, the joint shear strength for masonry with fiber mortar layer significantly increases when the fiber content is suitable, the joint shear strength decrease if the fiber content in mortar layer get less, fiber mortar layer effectively delay the formation of the cracks on the masonry surface and improve the ductility of shear failure, and also fiber mortar layer is efficient to avoid sudden collapse following crack.关键词：fiber mortar;shear strength;brickwork;failure mechanism;joint shear testing
- 1484
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:In order to repair many structures damaged after fire, the static axial compression test of steel reinforced recycled concrete columns (SRRCC) after high temperature was taken in two states: reinforced by CFRP or not. And the fatigue test was performed on the SRRCC after high temperature reinforced by CFRP. According to analysis on the failure mode, bearing capacity, load-displacement curve and load- strain curve, the results showed that: The CFRP could improve efficiently the compressive strength, ductility and stiffness; the increase rate could reach to 141%. The specimens whose replacement rate was 50% reinforced by CFRP get the maximum bearing capacity; the failure of reinforced specimens was caused mainly by CFRP pulled out, internal concrete crushed and upside of steel ribs buckled, while the non-reinforced specimens was failure induced only by upside of steel ribs buckled; the fatigue life of specimen 305RF under the maximum load equaled to 50% its bearing capacity exceed 200W cycled. The max vertical displacement at 200W cycles approached to that of static compression test.关键词：fibrous composite;Steel reinforced recycled concrete column;fatigue test;buckling
- 1809
- |
- 18
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:In order to analyze the parameter sensitivity of dynamic constitutive relationship,the shortcoming of the single factor analysis method was overcome by using the Latin hypercube sampling method in the entire parameter space,and by the use of nonparametric statistical method of spearman rank correlation analysis on constitutive parameters of the random input sample set and objective function of the corresponding output correlation analysis on the result set, the expression to solve the parameter sensitivity equivalently was set up in terms of Spearman rank correlation coefficient.The overall analysis of parameter sensitivity for dynamics relationship was realized.The reliability of the parameter sensitivity analysis results was improved obviously.Based on the parameter sensitivity analysis results,in order to further reduce the computational burden of the constitutive model parameters identification and search the optimal solution rapidly, accurately and reliably,the improved genetic algorithm was established by means of improved niche genetic algorithm,suspicious peak point judgment strategy and local accurate searching technology. The numerical calculation results showed that this method has markedly improved the global search ability of genetic algorithm and has high calculation precision.The parameter sensitivity integrity analysis method and improved genetic algorithm not only can well realize the parameters identification of the dynamic constitutive of titanium alloy,and the high precision recognition for other engineering material dynamic constitutive parameters has important reference value.关键词：titanium alloy;dynamic constitutive model;nonparametric statistics;overall analysis;Modified Genetic Algorithm
- 1487
- |
- 4
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:This paper presents the design and implementation of a real-time infrared and visible image fusion and transmission system based on heterogeneous multicore processor. It is a high speed and real-time image fusion embedded system which has architecture of heterogeneous multicore parallel. Heterogeneous multicore processor TMS320DM6467T is used as CPU for image fusion processing. This system combines the control capability of ARM and computation power of DSP, which meets the requirement of real-time processing. This system also implements image enhancement with Gray World algorithm and image fusion with Laplacian pyramid transform. The system fairly balances heavy computation burden and real-time requirement to some extent. The experiments indicate that the image fusion system works steadily and reliably. The heterogeneous computational architecture significantly improves the efficiency and performance in real-time fusion and data transmission.关键词：real-time image fusion;heterogeneous multicore processor;DSP;ARM
- 1757
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:In medical ultrasound imaging, the minimum variance (MV) adaptive beamforming method can improve the imaging resolution at expense of imaging contrast and robustness. In order to overcome this drawback, the amplitude and phase estimation (APES) adaptive beamforming method combined coherence factor (CF) was introduced. This method was based on the APES which had the merit including accurate amplitude estimation, improved imaging contrast and robustness; and then CF was used to weight the proposed method for reducing the level of noises and interferences and improving the imaging resolution. The simulated results showed that the proposed method in the aspects of imaging resolution and contrast was better than the conventional delay and sum (DAS), MV and original APES beamforming method.关键词：medical ultrasound imaging;adaptive beamforming;minimum variance;amplitude and phase estimation;coherence factor
- 1869
- |
- 12
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:Blurred or missing edges in image, especially ultrasound image could affect further processing, and traditional Modified Curvature Diffusion Equation’s parameters cannot be adaptive and iteration time is long. For these reasons, an adaptive modified curvature diffusion equation combined with Gaussian filter is proposed and Median Absolute Deviation in Robust Statistics is used to adjust the gradient magnitude threshold parameter automatically. This method can preserve image details effectively while remain MCDE's capacity for removing noise, and lower the time of iterations during filtering which improves efficiency in terms of time complexity. Moreover, MCDE's ability of preserving image details is further enhanced by applying adaptive gradient magnitude threshold. Experiments prove that our method inherits the advantages of MCDE, reduces human intervention and improves the efficiency of denoising.关键词：modified curvature diffusion equation;median absolute deviation;adaptive gradient magnitude threshold;medical image denoising
- 2193
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract: In order to solve single foggy image’s degradation quickly and efficiently, this paper proposed a dehazing method based on boundary constraint. The atmospheric-scattering-model based algorithm improved on boundary constraint to get transmission for the case that dehazing on bright areas of foggy image was more likely to cause distortion. What’s more, when it came to the optimization of transmission, we adopted a better performed color-image-to-grayscale algorithm. Experiments results showed great efficiency and feasibility of this algorithm with its greatest highlight that it also restored a high-quality haze-free image in bright areas and this algorithm tended to be more efficient compared with other algorithms.关键词：Single foggy image;boundary constraint;transmission;efficient
- 1636
- |
- 4
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:Most detecting algorithms which were confined to analyze packet could not describe DDoS completely. Without complete description, detection would be effected, thus could not provide effective information for network management. Concerning this issue, this paper proposed a novel approach based on packet-and-conversation-considering-with-context(PCC) time series analysis to detect DDoS attacks. By analyzing packet and conversation of DDoS traffic simultaneously, and combined with context information, multi-dimensional characteristics can describe DDoS better. And then support vector machine (SVM) classifier was adopted to establish the DDoS attack detection model from packet feature vector and conversation feature vector. Furthermore, a reliable alarm strategy was proposed to further reduce the influence of noise. The experiment results showed that PCC based approach can detect DDoS attacks effectively and reduce the influence of traffic noise.关键词：distributed denial of service;conversation;packet;context information;network noise
- 2047
- |
- 2
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:To guarantee that the robot reaches the target position without the collisions with the moving obstacles in a dynamic environment, a path planning method based on multi-agent particle swarm optimized particle filter (multi-agent particle swarm optimized particle filter, MAPSOPF) is presented by introducing multi-agent particle swarm optimization (multi-agent particle swarm optimization, MAPSO) to the particle filter (particle filter, PF). Through the communication and competition among particles in multi-agent system, the MAPSOPF algorithm can adjust the particles’ proposal distribution and update the prediction of particles. Compared with PSOPF algorithm, MAPSOPF algorithm can cut down iteration times by 50%~60% and reduce time consumption by 5%~50%. It can decrease time consumption by 95% in comparison with genetic algorithm. Among the three algorithms, the proposed algorithm can obtain the shortest path. The simulation experiment results verify that the optimized algorithm can solve path planning problem in dynamic environment effectively.关键词：path planning;dynamic environment;multi-agent particle swarm optimization algorithm
- 1758
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract: As chaotic sequence used for constructing measurement matrix in compressed sensing by sampling intervals sequence caused computing and storage resources wasting ,a algorithm of structuring measurement matrix was put forward based on Chebyshev-Bernoulli sequence in this paper. It used Chebyshev chaotic system to generate the chaotic sequence, then used be mapped spread spectrum sequence by the symbol function, at last, the spread spectrum sequence was proved obeying the Bernoulli distribution and then a measurement matrix had been constructed by it. Simulation results show that the measurement matrix in this paper had equal performance with random matrix and chaotic matrix. Chebyshev-Bernoulli measurement matrix show more excellent performance in reconstruction for Infrared image..关键词：Compressed sensing;measurement matrix;chaotic sequence;Bernoulli distribution;spread spectrum sequence
- 1594
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:During the recovery procedure, modulated wideband converter, a recently proposed sub-Nyquist sampling method, uses continuous to finite block to get the support set, which suffers high computational complexity, and thus slows down the recovery rate. So, a new method based on measurement vectors transform, called MVT, to get the support set is proposed. By integrating the continuous variable , it transforms infinite measurement vectors model into single measurement vector model, and then uses proven methods to solve single measurement vector model and to get the support set. Transforming infinite measurement vectors model into multiple measurement vectors model suffers high computational complexity, and slows down the whole recovery rate. This is avoided by MVT. And also, solving multiple measurement vectors model is more time-consuming than solving single measurement vector model. The experimental results show that MVT increases the recovery rate at least three times under appropriate number of sampling data.关键词：Compressed sensing;modulated wideband converter;sub-Nyquist sampling;infinite measurement vectors;multiple measurement vectors
- 1512
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:The correlation features of spreading codes in CDMA systems affect directly the capability of suppressing multiple-path interference and multi-access interference. Traditional codes used in CDMA have not ideal auto-correlation and cross-correlation properties at the same time, so complementary codes are introduced into CDMA systems. The user capacity of the system using complementary codes proposed in literature is limited to the subcode number in order to ensure perfect correlation. For improving the user capacity, the author proposed the even shift complementary code, which was suggested by the balanced quaternary spreading and modulation. The construction method of the proposed complementary code was also shown in this paper. The main feature of the even shift complementary code is that the supportable user number is twice as the subcode number. Meanwhile, with the help of the balanced quaternary spreading and modulation, the ideal correlation properties of the even shift complementary code is maintained. The simulation results showed that the CDMA system based on even shift codes could effectively suppress the multiple-path and multi-access interferences.关键词：CDMA;complementary code;balanced quaternary spreading and modulation
- 1541
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:In order to gain both bioactivity and antimicrobial ability, titanium with microporous/nanotubes structure on its surface was fabricated by acid etching and subsequently anodization at different voltages and bovine lactoferricin and alginates were loaded through layer by layer assembly. Samples were analyzed by scanning electron microscopy, X-ray photoelectron spectroscopy, contact angle test and the loaded drug amount was determined with ultraviolet spectrophotometer. Then the biomineralization ability was studied by biomimetic mineralization experiments. The results indicated that samples with nanotubes of bigger diameter carried more drugs. The materials are of good hydrophilicity. Also drug-loaded samples induced the mineralization.关键词：titanium;micro/nano structure;alginate;antimicrobial peptide;biomimetic mineralization
- 1322
- |
- 0
- |
- 0
发布时间：2023-11-14 - 摘要：Abstract:For the ill-posed problem caused by noise in the identification of bolt joint’s equivalent dynamic parameters based on frequency response functions (FRFs), an optimized identification method was put forward to obtain the accurate parameters. Nonlinear characteristics and coupling effect of the bolt joint were ignored, and the bolt joint was equivalent to spring-damper unit. Then the identification equations of the bolt joint’s tangential dynamic stiffness were established through substructure synthesis method. Through vibration experiment carried out on a specimen using LMS noise, vibration test system, the FRFs for identification were obtained. Then using the coherence functions simultaneously obtained with the FRFs to filter the FRFs to eliminate the noise’s influence on identification accuracy, and then the tangential dynamic stiffness of the bolt joint was identified based on the least square method. In the end, a harmonic response analysis was carried out on the FEM model of the bolt joint using the identified parameters. By comparing the measured FRFs with the simulated FRFs, the results show that the FEM model using the identified parameters can simulate the actual bolt joint very well and indicate that the proposed optimized identification method of bolt joint’s tangential dynamic stiffness in this paper has a good identification effect.关键词：FRF;bolt joint;substructure synthesis;dynamic stiffness;coherence function
- 1447
- |
- 2
- |
- 0
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