最新刊期
卷 45 ， 期 Z1 ， 2013
- 摘要：Abstract: High-water-content material stone serves as one of the filling materials in the underground goaf, its moisture content has a distinct impact on the deformation and failure character of the stone. The internal material structure was analysed by XRAD and SEM. The MTS was used to test the compression deformation failure character with different moisture content. The results show that the stone had a poor weather resistance, which makes it fit to use for damp closed mine; The tighter the structure of ettringite molecular was, the lower moisture content was and the less internal space and deformation were. The material presented plastic failure characteristics, whose longitudinal deformation was big and transverse deformation shrinked due to water of compaction. When the moisture content of stone increased, the elastic modulus and deformation modulus was reduced, moisture content increased by 6 percent, the elastic modulus reduced about 50 percent. Poisson's ratio remained unchanged with the moisture content change.关键词：moisture content;high-water-content material;SEM;deformation characteristics
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发布时间：2023-11-14 - 摘要：Abstract:In order to realize the simulation of landslide motion process, dynamic slice model for the simulation of landslide motion process has been derived from the differential equations of continuous motion theory. Compared with the traditional theory of hydrostatic lateral pressure, the lateral pressure determined by different motion states which is accord with the actual situation of the motion of geotechnical materials has been taken into account in this model. The numerical simulation analysis of Wachusett Dam is achieved by applying this model. The calculation results agree well with the actual situation, which verify the effectiveness of this model. According to the analysis, due to the fluid pressure, the Wachusett Dam landslide basically completed the main sliding and deformation in the first 12 seconds which all showed high mobility. At the same time, the accumulation form of the rear of landslide will be influenced by the tension cracks and the fluid pressure in the rear of landslide.关键词：landslide motion;dynamic slice method;numerical simulation
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发布时间：2023-11-14 - 摘要：Abstract:Abstract：Controlling the flue gas occupies a very important position in the tunnel fireproof safety design when the fire happens, and the critical wind velocity which is the minimum airflow speed without reflux can effectively control the flue gas at the source of fire under the direction of the wind in the process of tunnel fire , and it is the key to control the tunnel fire smoke. The CFD numerical simulation software simulated the smoke diffusion of different fire conditions of the road tunnels, and using SAP2000 respectively calculates the internal force size of the reinforced concrete tunnel in different critical wind velocity of different fire source locations when fire happens. After the comparative analysis, it should be appropriate to increase the critical wind velocity, so that it can effectively control the spread of the flue gas flow to avoid reflux, and it is also beneficial to reduce the tunnel structural damage in the condition of high temperature at the same time.关键词：Keywords: Critical wind speed;Tunnel fire;Tunnel lining;Temperature stress;Structural damage
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发布时间：2023-11-14 - 摘要：Abstract: In the Wenchuan Earthquake meizoseismal areas, numerous collapses and landslides triggered by the earthquake cause the debris flow hazard inducing environment drastically change, debris flow hazard occurs frequently and its prevention and mitigation is imminent. Taking Du Jiangyan Shenxi gully as the study area, based on analyzing post-earthquake debris flow hazard inducing environment, the hazard main-control factors including rich material source and susceptible geomorphology condition were determined, and the impact of the geomorphology condition including elevation, slop and aspect on debris flow were analyzed quantitatively using certainty coefficient method. Overlaid the study results with material source rich areas, the distribution of the most dangerous areas in Shenxi gully basin were delimited under the action of hazard main-control factors. The study results can provide a reference for analyzing the cause of frequent occurrence of debris flow hazards after the earthquake, and have important guiding significance for hazard assessment and zoning, disaster prevention and mitigation as well as economic construction and layout after the earthquake.关键词：Wenchuan earthquake;CF method;debris flow;main-control factors
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发布时间：2023-11-14 - 摘要：Abstract:High in-situ stress and low rock mass strength are the main characteristics of underground powerhouse of JinpingⅠhydropower station, surrounding rock stability problem is prominent during construction period. Combining with engineering geological mechanics method and three-dimensional finite element method, the construction process of underground powerhouse was simulated, discussed the stress and deformation of surrounding rock, stability characteristics and main influence factors of surrounding rock stability. The calculation results indicate that the stress and deformation and stability characteristics were obviously effected by fault, cavity arrangement and excavation procedure. During the excavation procedure, the maximum stress part is constantly changing, stress and deformation of surrounding rock are also continuously increasing, especially the deformation of the side wall. At grotto's intersection and fault location, deformation is large, plastic zone is basically connected; strengthened supporting measures should be taken to ensure the stability of surrounding rock.关键词：underground caverns;high in-situ stress;faults;surrounding rock mass stability;numerical simulation
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发布时间：2023-11-14 - 摘要：Abstract: This paper presents experimental research on the influence of weld access hole on fatigue of Q345c steel corrugated web girders by fatigue test, Static test and three-dimensional finite element stress analysis. The work was tested by Shimadzu 4890 fatigue testing machine.During the experiment, the fatigue test was carried out by three-point bending. The experimental phenomena and finite element analysis show that: the stress concentration occurs at the weld access hole of girder with corrugated steel web; geometry changes have a significant effect on the mechanical properties of the corrugated steel web beams.关键词：access hole;corrugated web girders;mechanical properties;fatigue;finite element analysis
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发布时间：2023-11-14 - 摘要：Abstract:Tensile test was performed on laser-MIG hybrid welded joint to investigate the profiles of local deformation in Base Metal (BM), Heat Affected Zone (HAZ) and Weld Zone (WZ), with the help of Digital Speckle Correlation (DSCM) Method. It was found that HAZ entered the yield stage firstly at the nominal stress of 48.5MPa because of the mechanical heterogeneity in welded joint and the total strain in HAZ went up rapidly along with the increase of axial loading, which was much larger than the nominal strain, leading to the final fracture. The result of hardness measurement showed that soft annealing in HAZ was observed obviously, which led to that HAZ became the weakest part in the tensile test of welded joint. A new prediction model for yield strength of BM, HAZ and WZ was proposed based on energy method and hardness measurement. A good agreement was reached between the predicted value and experimental results.
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发布时间：2023-11-14 - 摘要：Abstract:Six mixtures were designed according to the alkali-activated low calcium fly ash concrete using recycled aggregates (RA) to substitute nature coarse aggregates with different ratios(0%,50% and 100%). The compressive strength, elastic modulus and Poisson’s ratio of such geopolymer recycled concrete (GRC) were investigated and compared with various RA replacement ratios. The mechanical properties and failure mechanism of recycled aggregate concrete (RAC) and GRC were tested and discussed by scanning electron microscopy (SEM) analysis. The results show that, GRC concretes are stronger than RAC concretes at different ages. The compressive strength, elastic modulus and Poisson’s ratio decrease with the increasing of RAs content. The paste and interfacial transition zones (ITZs) are denser in GRC due to different matrix formation process and reaction products, which is the reason for the higher compressive strength of GRC. This research work is useful for the further study on engineering properties of such new concrete in structural performances.关键词：geopolymer;fly ash;recycled aggregate;compressive strength;microstructure;interfacial transition zone
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发布时间：2023-11-14 - 摘要：Abstract:According to the similarity theory made test beams which were in ShenZhen NanShan Bridge as the prototype and the shrinkage ratio was 1:20. Crack form, Cracking developing, displacement and strain stress response were studied. It turned out that the first bending crack appeared in the bottom edge and concrete floor and corrugated steel web connection, the maximum crack width was 5mm when destruction. In cyclic loads, the combination of the displacement response curve with three broken line model. The strain response of box girder’ roof is linear .loading and unloading section are coincidence. Concrete floor strain response curve slope have small change before cracking and change to be linear after cracking. Under bending load, the box girders with corrugated steel web are accord with the quasi plane assumption.关键词：box girders with corrugated steel web;crack;deflection;quasi plane assumption
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发布时间：2023-11-14 - 摘要：Abstract:The interference fit model of hollow shaft and sleeve was established in finite element software. The mechanical property of them was analyzed under axial tension, pressure load. And the effects of interference, hollow degree, axial loading, sleeve thickness on the mechanical property were studied. The results showed that there is still an "edge effect" about the contact stress and the equivalent stress of sleeve under axial loading. The maximum equivalent stress of hollow shaft appears on the inside cylindrical surface under tensile loading. Under axial tensile loading, contact stress and the equivalent stress of sleeve increased with the increase of interference, sleeve thickness, and decreased with the increase of hollow degree and load. The equivalent stress of hollow shaft increased with the increase of the four parameters.关键词：interference fit;axial loading;mechanical property;finite element
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发布时间：2023-11-14 - 摘要：Abstract: Multi-crack problem has become a key issue in the field of rock mechanics as well as its related disciplines. In this paper, three symmetric collinear cracks in an infinite plate under biaxial compression have been investigated. Considering crack surface friction and the effect of the interval distance between two adjacent cracks, and combining complex stress function theory, the exact analytical solution of stress intensity factor (SIF) for three collinear cracks inside an infinite plate under biaxial compression is presented. The effects of the confining stress as well as the interval distance between two adjacent cracks on SIF have been analyzed through the calculation results. The corresponding photoelastic experiments were conducted and the results agree with the analytical result. The results show that SIF decreases as confining stress increases, and SIF increases as the interval distance between two adjacent cracks decreases.关键词：stress intensity factor. analytical solution, confining stress, crack distance
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发布时间：2023-11-14 - 摘要：Abstract:Bioengineering stabilization of slope is restricted to shallow slope soil beneath slope surface 1 meter, therefore root reinforcement can In order to improve the stability of slope, root-cable-gabion net flexible system is developed to control progressive deformation of slope, i.e., when flexible gabion net retaining wall is pushed forward by slope soil, steel cable linked between trees and the wall will pull root system, while root system is an anchorage. Therefore slope soil at foot is compressed rather than in shear and progressive deformation of slope and flexible retaining wall is constrained. Mechanical and finite element analyses are performed on the root-cable-gabion net system adaptively stabilized slope. The results show that due to the flexibility of gabion net retaining wall, root-cable-gabion net system can effectively limit and reduce the progressive deformation of slope and maintain the slope stable.关键词：Bioengineering stabilization of slope, flexible retaining wall, root-cable-gabion net system, deformation self-adaption, rainfall induced landslide
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发布时间：2023-11-14 - 摘要：Abstract: Most landslide and collapse formed viscous landslip-collapse soil composed of coarse particle and viscous gap filling. The influence of gap filling viscosity to the motion of landslip-collapse soil was few discussed. In order to analyze the influence of it, the normal-force and tangential-force of the certain density（1.360g/cm3） Chengdu clay were admeasured through experiments by MCR-301 Rheometer. Using the PFC3D, the numerical model of landslip-collapse soil was constructed and divided five parts. Every specific particle represents different parts of landslip-collapse soil. Through compared analysis of motion process about different parts particles under set normal and tangential bond strengths (0 Pa, 200Pa), the results showed, the starting forms of landslip-collapse soil was push type when the bond strength was set to 200Pa, but was skid type when the bond strength was 0 Pa. The peak velocity of particle at 200 Pa was smaller, while the collision frequency and velocity fluctuation amplitude were higher than the values at 0 Pa.关键词：landslip-collapse soil;viscosity;process of motion;comparison analysis;PFC3D
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发布时间：2023-11-14 - 摘要：Abstract:Bingham model can describe the slow movement of natural slopes. Nonlinear viscosity is taken into account in Bingham constitutive equation due to the existing of pore water pressure. Then an explicit expression can be derived by simplifying the viscosity and root-reinforcement functions. The numerical methods can also be used in other complicated boundary problems. The proposed formula based on Bingham model is applied to describe one typical creeping soil slope. The concept of shear layer can be easily emerged by the formula with fewer model parameters. The reinforcement of root relies on the affecting depth and time.
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发布时间：2023-11-14 - 摘要：Abstract:A new miniature system for cleaning RO (reverse osmosis) membranes by using alkaline solution and ultrasonic was set up and used for researching cleaning effect of inorganic and organic pollutants on the RO membrane by continuous monitoring cleaning solution’s conductivity and absorbance. Firstly, we screened the ultrasonic frequency and sound intensity, the result showed that the optimum frequency and sound intensity was 50 KHz and 0.636W cm-2 separately; Secondly, we screened the soaking time and ultrasonic time of the RO membrane, and the soaking time was not less than 60 min and the ultrasonic time was not more than 60 min. Then, under the screened conditions above, we investigated the effects of NaOH solution’s concentrations for cleaning the inorganic and organic pollutants on the RO membrane with this system. The results showed that the procedure of alkaline solution circular cleaning and ultrasound-assisted cleaning had very good efficiency for the inorganic pollutants on the RO membrane; the procedure of alkaline solution circular cleaning had only a little efficiency for the organic pollutants on the RO membrane, but the procedure of ultrasound-assisted cleaning had very good efficiency; the NaOH solution with concentration of 6 mmol L-1 had the best cleaning efficiency for the pollutants on the RO membrane and the elution rate of the dirt was 33%.关键词：RO membrane;alkaline solution;ultrasonic;conductivity;absorbance
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发布时间：2023-11-14 - 摘要：Abstract:Intermittent aeration moving bed biofilm reactor (IAMBBR) has high pollutant removal efficiency in treating wastewater, and could improve the total nitrogen (TN) removal in the MBBR process, especially suitable for depth processing nitrogenous wastewater．Effect of organic loading and aeration mode on pollutants removal performance of the IAMBBR in treating nitrogenous wastewater was studied in the experiments. The results indicated that average removal efficiencies of COD、ammonium and TN were 95.88%、92.22% and 76.73% with influent COD、ammonium and NO3--N concentration of 720, 20 and 100 mg/L, respectively, when the IAMBBR was operated with HRT of 12h, temperature of 25±2℃，pH of 6~9, organic loading of 1.44kg COD/(m3·d) and circulating aeration of 2h aeration and 4h stop aeration. And better organic pollutants and nitrogen removal performance could be achieved in single reactor. Meanwhile，operation mode of the IAMBBR had significant influence on biofilm morphology adhering to suspended carriers.关键词：Intermittent aeration moving bed biofilm reactor;organic loading;aeration mode;nitrogenous wastewater;depth processing
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发布时间：2023-11-14 - 摘要：Abstract:The Ni-W alloy coating was prepared on the surface of N80 steel with electroplating method, the coating surface and interface morphologies and the distributions of chemical elements were analyzed with SEM and EDS, respectively, and its phases was measured with XRD. The capability of salt spray corrosion for the Ni-P coating in 5% NaCl solution was tested, and the mechanism of salt spray resistance was discussed. The experimental results show that the coating thickness is about 40µm, the main phase of the coating is Ni-W, the Ni and W elements are presented in the coating with metal form; The diffusion phenomenon of chemical elements is produced in the coating-substrate interface after high temperature treatment, and forming metallurgical bonding; after the salt spray corrosion, corrosion products on the coating surface are oxides and chlorides of Fe, the substrate has no corrosion phenomenon.
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发布时间：2023-11-14 - 摘要：Abstract: The TiN and AlTiN coatings were prepared on Cr12MoV steel substrate by physical vapor deposition (PVD) method, the morphologies, phase and bonding strength of the coating surface and interface were analyzed by SEM, XRD and scratching tester respectively, and the friction-wear test of the coating was processed. The results show that TiN and AlTiN coatings have higher hardness, the surface roughness of the AlTiN coating is better than that of the TiN coating, the average deviation of the surface profile arithmetic Ra of TiN coating is 328.91nm, while that of AlTiN coating is 112.49nm. Binding strength of TiN coating is 28.8N, and that of AlTiN coating is only 15.05N. Friction coefficient of AlTiN coating slightly higher than that of TiN coating in running-in period and fluctuation period, and friction coefficients of the two coatings are almost same in the stable period, which maintains at about 0.44-0.46. Compared with TiN coating, toughness of AlTiN coating has improved than that of TiN coating, and its wear performance is better than that of TiN coating.关键词：TiN coating;AlTiN coating;physical vapor deposition;bonding strength;friction coefficient;wear property
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发布时间：2023-11-14 - 摘要：Abstract:The amorphous Ni-P coating was prepared on the surface of ZL113 aluminum alloy by chemical plating, the coating were heat treated at a series temperature of 300℃-400℃ for 80min, the surface morphologies and phase compositions of the coating were characterized with SEM and XRD, respectively, and the wear mechanism of Ni-P coating was examined by friction-wear test. The results show that the crystal dimensions of Ni-P coating by chemical plating are grew up with the heat treatment temperatures. The coating hardness increases with the heat treatment temperatures, showing similar Gaussian distribution, and reaches the maximum of 611.2HV at 350℃. The heat treatment temperatures have little effect on friction coefficient by the wear test, the wear process is divided into three stages, i.e. abrasive wear, adhesive-abrasive wear and adhesive wear, and the wear resistance is the best at 350℃.
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发布时间：2023-11-14 - 摘要：Abstract: The multi-physics fields coupling sintering is a novel method for preparing components fast sintered under low temperature with powder materials. In order to investigate the electro- heating impact on shrinkage and densification of multi-physics fields coupling sintering during the rapid heating process, suppressed pure Fe cylinder sample was firstly heated to 825℃ at the preset heating rate of 50℃/s , and then cooled down to 400℃ without heat preservation. After that, the sample was heated at the same heating rate and cooled again between 825℃ and 400℃ for 5 cycles. The whole process was carried out by Gleeble-1500D thermal simulation instrument. Further, the sample was compared with those of traditional vacuum sintering. It is demonstrated that for the multi-physics fields coupling sintering the sample appeared severe contraction at low temperature during the fast temperature rising due to the heating shock. After 2 minutes' electro-heating impact cycle, the powder compact has been realized to relative density of 97.55%, compared with traditional vacuum sintering technology where the powder compact was sintered at 1125℃, the holding time was 60 minutes, the relative density is 85.70%. Finally, it can be concluded that the heating impact of multi-physics fields coupling sintering was a new method to realize density in comparison with the long holding time traditional vacuum sintering.关键词：multi-physics fields coupling sintering;electro-heating impact;shrinkage;densification
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发布时间：2023-11-14 - 摘要：Abstract:Micro components of Φ1.0mm×1.0mm of 316L stainless steel were fabricated by using Gleeble-1500D. The effects of heating rate and sintering temperature on the microstructure and mechanical properties were studied. The result show that the pores reduced and relative density of the sintered body increased obviously with the increase of heating rates and sintering temperature. The sintered samples can be close to full density when the heating rate was 50℃/s and sintering temperature was 900℃. And the sintering temperature was lower than the sintering temperature of traditional method. Analysis of axial reduction of cylindrical compacts showed that the peak value appeared during the sintering period, which suggested that heating rate is more important than the sintering temperature on the densification.关键词：micro-Fast;heating rate;sintering temperature;densification;316L stainless steel powders
- 1939
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发布时间：2023-11-14 - 摘要：Abstract:Liquid nitriding of 17-4 PH martensitic precipitation hardening stainless steels was conducted at 430 °C for different time using a complex chemical heat-treatment, and the erosion corrosion resistance of the nitrided samples was evaluated. Experimental results revealed that the main phase of the nitrided layer was expanded austenite (S), CrN、Fe4N and Fe2N， when 17-4PH stainless steel was subjected to complex salt bathing nitriding,. The nitrided layer depth thickened intensively with the increasing nitrding temperature. The salt bath nitriding can effectively improve the surface hardness. The maximum values measured from the treated surface are observed to be approximate 1100 HV0.1 for 40 hours from the untreated material (309 HV0.1). Low temperature nitriding can improve the erosion corrosion resistance against two phases flow. After nitrided for 4 hours, the sample has the best corrosion resistance than others.关键词：17-4PH stainless steel;Low temperature liquid nitriding;microstructure;Erosion corrosion
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发布时间：2023-11-14 - 摘要：Abstract:Laboratory experiments were carried out to investigate the erosion-corrosion resistance of 5 groups austenitic cast iron of different content of nickel under 2% H2SO4, 15% sand liquid-solid impingement conditions. The electrochemical characteristics have been examined via the CS electrochemical active station. Comparative study the erosion-corrosion resistance and corrosion resistance of high/low nickel cast iron. The results showed that：In 2% H2SO4 solution, the polarization curves of nickel austentic cast irons were similar, both appeared a passivation region. It has been shown in this paper that the cast iron which Ni content is 8.36%，Mn content is 6.57% exhbits better corrosion resistance than other low-nickel cast irons, close to the high-nickel cast iron.关键词：austenitic cast iron,H2SO4 solution,erosion-corrosion,electrochemical corrosion, polarization curve
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发布时间：2023-11-14 - 摘要：Abstract: A novel particle filter approach was presented in this paper for robust object tracking using a multi-region based discriminative modeling mechanism. Conventional particle trackers usually take the target region as a whole and may easily be confused by the similar pixels from non-object region. In contrast, the proposed method highlights the most effective information of foreground/background discrimination and divided the object into a number of patches. By comparing the properties of within and between classes of the patch and background, the most informative patches are selected. Moreover, based on these selected patches, the proposed algorithm commanded both the photometric and spatial information in a Bayesian manner for target modeling. This discriminative appearance model was then used in updating step of the particle filter to measure the object region. Experimental results on several challenging video sequences had verified that the proposed method was compared very robust and effective with the traditional particle filter in many complicated scenes.关键词：visual tracking;particle filter;discrimination;target appearance
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发布时间：2023-11-14 - 摘要：Abstract:In this paper, a new image sequences blind super-resolution algorithm was proposed to reduce the influence on super-resolution construction caused by point spread function estimation error. First, we use slanted-edge method to achieve an accurate estimate of the image system’s point spread function, then combined the point spread function with the iterative back projection super-resolution construction algorithm to finish the super-resolution construction. Experimental results indicate that the proposed method needs shorter operation time and doesn’t limited by the blur degree of the low resolution image. The construction result is of higher peak signal to noise ratio (PSNR) and structure similarity (SSIM) and lager extent of the image’s true resolution.关键词：Blind super-resolution construction, slanted-edge method, iterative back projection , image sequence
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发布时间：2023-11-14 - 摘要：Abstract:This paper proposes an algorithm for detecting the thinn and unclear roads in an arial image. The algorithm firstly smoothed an image by using a Guacian filter, then useed fractional diferencial operator to enhance the image for sharpening the roads, finally applied a proposed ridge edge detection sub-algorithm to detect the roads (lines and curves). For each detecting point, the new ridge detection algorithm detected lines in four different directions, to determine if the detecting point is the cadidate of the ridge edge point. After that, the extracted lines were smoothed by using the lengths and orientations of the lines, the gaps in curves or lines were connected based on artificial intelligent method, and the noised lines or pixls were removed. If roads were thick, the image was shrinked to the road width of 4-8 pixels, then, the detecting result was returned to the original image. In experiments, the studied algorithm had the better road detection results, especially for the thin and fuzzy roads, and the testing results showed that it was satisfactory.关键词：roads;arial image;fractional differencial;ridge edges
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发布时间：2023-11-14 - 摘要：Abstract:The current automatic white balance algorithm in which single color modification coefficient is used for all pixels has the deficiency of larger color error. A new automatic white balance algorithm was proposed, which could calculate the color modification coefficient according to the lightness in HSL color space. The HSL color space of an image was analyzed in order to divide the lightness into several segments and pixels in each segment were classified into one group. All pixels near to gray axis in the same group were figured out, the color modification coefficient was calculated based on the average value of color components of all pixels, and then the color of all pixels in this group were modified according to the color modification coefficient. Image data for standard color card in several kinds of color temperature were captured and analyzed respectively according to automatic white balance algorithms, which include HSL gray axis method, gray world method and perfect reflector method. Color error between calculated results of standard cards was analyzed. It showed that HSL gray axis method had much better light environment adaptability and better color reproduction capability.。关键词：HSL color space;automatic white balance;HSL gray axis method;gray world method;perfect reflector method
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发布时间：2023-11-14 - 摘要：Abstract:Traditional medicinal material classification methods suffered from inefficiency and being susceptible to human factor. In this paper, a Multi-sensor information fusion classification and identification system was proposed. Firstly, this system quantized medicinal material features from image sensors, gas sensors and taste sensors. Secondly, high dimension features from both training and testing samples of medicinal materials were extracted. In the end, feature matrix was created and SVM algorithm was adopted for recognition purpose. Through experiment and visual measurement, medicinal material classification system is multi-functional one including image acquisition, feature extraction, feature analysis, model building and classification. It can not only classify medicinal material between different classes, but also identify grade in the same class.关键词：Multi-sensor information fusion;Medicinal materials classification;Feature extraction;Support vector machine
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发布时间：2023-11-14 - 摘要：Abstract: In order to expedite the dissipation of flight delay wave after air traffic flow control, the multi airports coordination optimizing strategy model was proposed, which considered the key points limited by the traffic flow. It optimized the departure traffic flow with the coordinating of several concerned airports, which reduced the flight delay wave caused by air traffic flow control and took into account on schedule rate of relevant airports at the same time. The grouping principle for ground holding issues and the priority determination algorithm was designed in the model. The model is based on the following considerations: different delay costs of different flights and cumulate delay costs effect caused by subsequent flights. Compared with first-come-first-service model, the experimental results showed that the total delay time of the proposed model has been reduced by 11.5% and the total delay cost decreased by 9.5% based on this model. It could also show the different ground delay strategies based on the restricted airspace boundary entrance intervals and the takeoff separation changs of departure airports, which demonstrated the flexibility and optimization of this model.关键词：air traffic flow management;Ground Delay strategy;total delay time;total cumulate delay cost
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发布时间：2023-11-14 - 摘要：Abstract:Current approaches to improve the rate of load balance in cloud data centers did not investigate the problem of combining different workload types. The static and dynamic load balancing scheduling algorithms based on heterogeneous workloads were proposed. The new VM was allocated to a certain PM using the static load balancing scheduling algorithm. And the VMs on high load PM were migrated to the low load PMs using the dynamic load balancing scheduling algorithm. The simulation results showed that the new load balancing scheduling scheme improved the rate of load balance in cloud data centers and the multi-dimensional resources in a single node had good balanced utilizations.关键词：load balance;scheduling;cloud data center;Virtual machine
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发布时间：2023-11-14 - 摘要：Abstract:Large dimensional multi-objective optimization is a common topic in engineering application. The conventional multi-objective optimization algorithms are inefficient in the problem of which the objectives number exceeds four. For the problems of conventional and the current dimensional reduction algorithms, a group divided dimensional reduction evolutionary algorithm is put forward. For this algorithm, the objective functions are divided into several groups, sub non-dominated set of every function group is built separately using SPEA2, then the non-dominated set of all objective functions is obtained basing on the sub non-dominated sets. The feasibility of this method is proved theoretically. For the sake of engineering application, individual fitness of SPEA2 is modified. In the simulation, this method is compared with current large dimensional reduction algorithms in terms of some metrics on two test problems. The test results show us the better performance of the algorithm.
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发布时间：2023-11-14 - 摘要：Abstract:In order to extract the pathological information of heart sounds accurately, an improved method of feature extraction based on lifting wavelet transform analysis was proposed to analyze the first and second heart sounds and recognition different heart sounds purposefully. Firstly, lifting wavelet transform was applied to decrease noises of different heart sounds by soft threshold method. Secondly, lifting wavelet-time entropy was used to describe the distribution on time domain and extract the entropy; the Shannon energy and improved dual-threshold were then applied to extract the envelope and time of heart sounds. Finally, the best feature elements were analyzed by using SVM, which was used for the classification of sixty different heart sounds. It was observed these heart sounds were successfully classified as the accuracy was 98%.关键词：heart sounds;lifting wavelet transform;dual-threshold of Shannon energy;feature extraction;SVM
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发布时间：2023-11-14 - 摘要：Abstract:It is a critical issue to identify the existence of a crank of a multiple loop mechanism, which is most fundamental and difficult problem in the process of mechanism analysis and synthesis. In this paper, identification of a crank in spherical Stephenson-III six-bar mechanism has been investigated. The mechanism was divided into two units, a spherical four-bar linkage and a spherical two-bar. By means of spherical trigonometry, the discriminant for detection of a crank of spherical four-bar linkage was presented at first. After that, combining that discriminant with assembly condition, the conditions of crank existence of spherical Stephenson-III six-bar mechanism were derived out. Finally, two examples have been employed to valid the discriminant presented in this paper.关键词：Spherical Stephenson-III six-bar mechanism;Condition of crank existence;Spherical trigonometry;Spherical four-bar mechanism;Assemble condition
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发布时间：2023-11-14 - 摘要：Abstract:Firstly, the basic structure of variable frequency pump-control steering hydraulic system of a hybrid wheel loader was illustrated. Secondly, the exact linearization of IPMSM system was realized by state feedback based on differential geometry, and combined with H∞ control method as well as improved quantum-behaved particle swarm optimization , the robust controller of IPMSM was solved. Simulation results show that the variable frequency pump-control system meets requirements of load conditions of wheel loader’s steering system, and its energy efficiency is higher than valve-control steering hydraulic system and normal variable displacement pump system.关键词：Wheel loader;Hydraulic steering system;Mixed sensitivity;robust control
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发布时间：2023-11-14 - 摘要：Abstract:The hydrodynamic lubrication model of sliding friction pair with surface texture was calculated by using numerical methods. The effect of surface texture on the lubrication performance of friction pair was theoretically analyzed based on different cross-sections and surface profiles. The optimal parameter and type of surface texture were obtained under specific condition. Results show that there is a great influence on the frictional coefficient and carrying capacity of friction pair caused by different cross-sections and surface profiles of surface texture; all of the cross-sections have an optimal diameter making the frictional coefficient minimum. It was discovered that making the underside of micro-pits with rectangular cross-section tilted improves the carrying capacity of textured region significantly and reduces the frictional coefficient largely. In all kinds of typical surface profiles, the inverted triangle surface profile whose bottom edge close to the entrance obtains the best lubrication performance. Moreover, great improvement was acquired on carrying capacity if tilted underside and surface profiles are combined optimally.
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发布时间：2023-11-14 - 摘要：Abstract: Research on the single diameter of a downhole throttling valve that can‘t adapt to the various pressure and temperature in the downhole environment，putting forward a new downhole intelligent throttling system based on the conventional downhole throttling device and the adjustable poppet valve. The system reduces the gas pressure through changing the flow area. Via the downhole temperature and pressure monitored by the sensors, the system’s Industrial Personal Computer can process the data and send a signal to allow the motor to rotate to regulate the open rate of the poppet valve in real time. Then get the stable flow rate and outlet pressure at the outlet. Using ANSYS analysis software to simulate the downhole flow filed. The results show that the throttling structure of the downhole intelligent throttling system is workable, and the simulation forms the theoretical foundation to establish the throttling system.关键词：natural gas downhole throttling;intelligent system;poppet valve;ANSYS fluid analysis
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发布时间：2023-11-14 - 摘要：Abstract:A new load sharing two-stage planetary gear transmission system for wind turbine gearbox was proposed. A formula for computing the transmission ratio was given by using the kinematic inversion method. By means of simulative analysis, it was tested that the transmission ratio increases as the value of characteristic parameter of planetary gear train. When the ratio was in the interval [3, 8], the maximum value was 73. Optimization design model with minimal volume was established, in which the boundary constraints were considered. The analysis showed that the optimal method was an effectibe way to reduce the volume of the three-stage planetary gearbox.关键词：increasing gearbox;load sharing;transmission mechanism design;wind power gear;characteristic parameter of planetary gear train
- 1923
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发布时间：2023-11-14
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