最新刊期
卷 48 ， 期 Z1 ， 2016
- 摘要：Abstract:Protected coal seam mining is the main mining method for the regional gas control, however, its pressure relief effect can not be quantized currently as the lack of evaluation system. Based on the mining-enhanced permeability theory, a numerical model was established by the discrete element method on the geological conditions of No. 10 mine of Pingdingshan coal mining group, then the contour maps of mining-enhanced permeability were obtained. The result indicated that: when the protective layer was mined, the peak value of pressure occured 15 m ahead of working face; the mining-enhanced permeability and the gas flow presented a positive correlation. At the bottom of the goaf, the distressed zone had roughly the same distribution with the mining-enhanced permeability. The results confirmed that the mining-enhanced permeability theory can be used to evaluate the effect of pressure relief, which can provide a more scientific foundation for the design of protected coal seam mining and gas drainage scope.关键词：protected coal seam mining;mining-enhanced permeability;pressure relief;numerical simulation
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发布时间：2023-11-14 - 摘要：Abstract:This paper lists the applications and the flood discharge atomization of ski-jump energy dissipation and underflow energy dissipation in some hydropower stations. The Xiangjiaba hydropower station adopted multi-horizontal submerged jets pattern, in view of energy dissipation pattern of the station, and 17 physical parameters of the efficiency effects which influenced by energy dissipation pattern were analyzed. When only the surface outlets were operating in flood discharge, the flow pattern evolution was from free jet, semi-submerged jet, submerged jet to return underflow respectively; when only the middle outlets were operating, with the change of downstream water level, the bias flow appeared and then disappeared by the rise of the downstream water level, the spatial diffusion ratio was more obviously than the flow pattern evolution at the same time; when both the seven outlets and middle outlets were operating, the downstream water level had obvious effects on the flow pattern evolution, the contraction of surface outlets had obvious influence in the flow pattern evolution. Studies have shown that: flood discharge with surface outlets alone, the parameters influenced the maximum underflow velocity are elevation of drop-still in outlets and Froude number of flow; flood discharge with middle outlets alone, the parameters influenced the maximum underflow velocity are elevation of drop-still in outlet and drop-still bottom slope ratio; flood discharge with surface outlets and middle outlets, the parameters influenced the maximum underflow velocity are contraction ratio of surface outlets, side contraction ratio of surface outlets, height deviation of surface-middle outlets, Froude number of flow in surface-middle outlets and drop-still bottom slope ratio in middle outlets. This paper looks forward to the research prospects of energy dissipation in flood discharge of the high head, large flow and low atomization.关键词：Multi-horizontal submerged jets;flow pattern evolution;the maximum underflow velocity;low atomization
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发布时间：2023-11-14 - 摘要：Abstract:With the existence of congeries in the river channel,the hydraulic characteristics were changed.In order to analyze the mechanism of accumulation in different water resistance, the flume experiment was carried out.The change of hydraulic characteristic caused by different sizes of congeries was obtained by controlling the slope of the bed surface,the size of the congeries and the flow of upstream.The result showed that the height and the range of backwater were larger due to the smaller flow and the larger congeries with the same slope of water channel.With the increasing of water channel slope,the water changed from subcritical flow to riffle, in the same conditions.The additional gradient increased with the increase of congeries size.But the additional gradient decreased with the increase of congeries size if the water turned into riffle.关键词：congeries;backwater;additional gradient;Froude number
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发布时间：2023-11-14 - 摘要：Abstract:Abstract: In order to solve the problem of mountain river to river morphology with the changes of uncertainly sediment supply conditions, based on J. G. Venditti series of flume experiments in sediment supply, coinciding fully the characteristics of bed load sediment movement, a parameter Sp was introduced to describe the intensity of a riverbed form. Study on effects of incoming sediment change on river bed-form , bed load transport and sediment gradation. Results showed that, adding sand to the river bed of the river will affect the bed morphology, bed-load transport rate and channel grading in an armor layer. Sediment supply will caused river bottom again appeared rushed silt changes, eventually variable increase the slope , variable serious the scour and eventually reduce the intensity of the river bed structure Sp; Sediment supply will increase the bed-load transport rate, and sediment supply grain diameter sand for 3 mm of sediment for travelling bed load , and in the value grain diameter for 8 mm of sediment for structure bed load; Sediment supply will refinement river, which grain diameter smaller effect than grain diameter larger of particles effect obviously.After joining the median particle size of 3mm sand over mass median particle size decreases and then increases and median particle size of coarse 8mm insteadly.关键词：pebble river;sediment supply;bed-form;bed load transport rate;riverbed gradation
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发布时间：2023-11-14 - 摘要：Abstract:In order to explore the impacts of flow velocity on growth of dominant species of algae-bloom in reservoirs, a laboratory experiment was conducted to examine the responses of the algae growth, water quality, lipid oxidation and antioxidant system of Microcystis aeruginosa under different flow velocities (0-0.3 m/s). Significant differences were found in the growth of M. aeruginosa under different flow velocities, namely the low flow velocity promoting the algae growth and the high flow velocity inhibiting growth. The algae under 0.1 m/s grew best with the fastest consumption of total nitrogen and total phosphorus, while the algae under 0.3 m/s grew significantly worse than static group. Along with the growth of algae, the water pH tended to be weakly alkaline, the dissolved oxygen content in water increased slowly and water turbidity kept high correlation with algae density. MDA content and antioxidant enzymes (SOD, CAT, POD) activity of the algae under 0.3 m/s was significantly higher than the other groups. The results showed that a certain rage of flow velocity could improve the floating and aggregation of algae, promote absorbing light energy, enhance the nutrient absorption of the algae and reduce the oxidation degree of algae cells. The empirical formulas of algae growth prediction under hydrodynamic conditions during experiment period were established, and the advantaged flow velocity for the algae growth was determined to be 0.15 m/s. The outcome might provide a theoretical basis for the prediction of eutrophication trend of reservoir and useful reference for the prevention and control of M. aeruginosa bloom.关键词：hydrodynamic condition;algae bloom;Microcystis aeruginosa;advantaged flow velocity;antioxidant enzyme;eutrophication
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发布时间：2023-11-14 - 摘要：Abstract:To study the dynamic characteristics of one proposed tailing dam, its dynamic characteristics with two inputs of seismic motion were studied based on its survey data. The physical variables and their variations, such as effective stress, dynamic displacement, permanent displacement, stress level, the coefficient of horizontal acceleration amplification of the tailings dam, were analyzed in detail. At the same time, liquefaction resistances under two seismic loading effects were also evaluated separately. The results indicate that the tailing dam under the above dynamic load effects was at lower stress levels, with a large safety margin, and the pore water pressure in the dam was in a reasonable range, therefore the soil elements in the dam would not liquefy.关键词：tailing dam;seismic motion;dynamic characteristics;liquefaction evaluation
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发布时间：2023-11-14 - 摘要：Abstract:Shapai RCC dam is a arch dam more than one hundred meters high, and it is one of the few examples withstood the earthquake, so the dynamic stability reanalysis of dam abutment is significant. Combining with the advantages of the finite element method and limit equilibrium method, the limit cumulative displacement formula is put forward and acted as the stability criterion of slider, dynamic stability analysis of Shapai arch dam’s abutment is conducted under two seismic waves and the overload study of Shapai arch dam is conducted under the artificial waves reflecting the 5.12 earthquake. The results show that Shapai arch dam’s abutment is stable under the impact of artificial waves (ah=2.05 m/s2) , which is consistent with the actual seismic effects. However, under the action of design waves（ah=5.31m/s2）, the Shapai arch dam’s left bank abutment is unstable, but on the right bank, the abutment keeps stable. When the left bank slider L1、L2 withstand the 3.2、3.6 times artificial wave respectively, the instability happens on the two sliders. The instability happens on the right bank slider when there is a 4.2 times overload. The slip direction and the influence of safety factor changing with time to cumulative displacement are considered. The abutment slider slip rule is reflected more practically and a new way of abutment dynamic stability analysis is provided in practical engineering.关键词：Shapai arch dam;abutment slider;dynamic stability;5.12 seism;overload analysis
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发布时间：2023-11-14 - 摘要：Abstract: To study the influences of temperature variation and thermal insulation on the cracking state of dam-embedded steel penstock encircled by cushion layer at runtime in cold region, the concrete damage and bearing characteristics of one penstock under temperature action were analyzed by nonlinear finite element method based on the concrete plastic-damage model. The results indicated that due to the cushion layer there was little damage on the concrete and no macro-cracks would appear on the concrete surface under normal operation condition. Temperature drop leaded to serious damage at the top of pipe, and temperature rise leaded to damage at the bottom of the pipe , in the meantime the stresses of reinforcement within damage zone increased apparently; thermal insulation slab could help reduce temperature load, concrete damage and reinforcement stress efficiently, and the thicker the better, but after the thickness of the slab increased to a certain extent, its effect would tend to be stable. In different engineering the thickness of thermal insulation slab can be controlled by the width of the cracks.关键词：hydraulic structure;dam-embedded steel penstock encircled by cushion layer;damage;temperature load;thermal insulation
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发布时间：2023-11-14 - 摘要：Abstract:In order to detect the dynamic mechanism of dry/wet changes and drought/flood prediction theory in hilly area of central Sichuan, potential evaporation was calculated with Penman-Monteith model and humid index was constructed, based on daily meteorological data from 1958 to 2013 of 8 sites in hilly area of central Sichuan. On this basis, the long-range correlations of monthly, seasonal and extreme dryness/wetness humid index were analyzed with detrended fluctuation analysis(DFA), and then the influential meteorological factors of the long-range correlation of humid index were discussed. The results showed that monthly humid index in the areas except Nanchong and Suining had long-range correlation, but was not entirely random. Both of seasonal and extreme dryness/wetness humid index had long-range correlation. For different seasons, summer had a strongest correlation, followed by autumn, winter and spring. For extreme climate, the long-range correlation of extreme wetness was weaker than extreme dryness. By analyzing the consistency of long-range correlation between humidity index and meteorological factors, it showed that scale exponent of precipitation was significantly and positively correlated with scale exponent of relative humidity.关键词：hilly area of central Sichuan;long-range correlation;detrended fluctuation analysis (DFA);humidity index;influential factor
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发布时间：2023-11-14 - 摘要：Abstract:Abstract: In order to distinguishing the impacts on climate change and irrigation on reference crop evapotranspiration (ET0), the daily ET0 estimated by Penman-Monteith equation in 5 meteorological stations of Dujiangyan Irrigated Area were used to analyze the trend of ET0. The result showed that: in recent 60 years, the ET0 in the area had a downward trend as a whole, Relative humidity was the most sensitive to ET0 in these climate variables, and mean air temperature was the second, sunshine duration and wind speed were lower. In recent 60 years, the reduce of wind speed and sunshine duration was the main reason of the declining of ET0. Compared with the prior to the construction of irrigation area and irrigation area expansion period, the down trend of wind speed was far higher than that nationwide, so the influence of irrigation on local climate of the area realized by reducing wind speed in the area. In spring, summer, autumn, winter, and the main crop growth period, the main control factors of ET0’s change were mean air temperature, relative humidity, mean air temperature, relative humidity and relative humidity. The influence of irrigation and climate change on ET0 in Dujiangyan Irrigation Area were respectively 49.97% and 50.03%, so climate change and irrigation were important factors to influence ET0 in the irrigation area.
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发布时间：2023-11-14 - 摘要：Abstract:In view of the structural of soil impact on the stability of the slope, the Binary Medium Model (BMM), is defined as bonding elements and frictional elements which are idealized as elastic-brittle element and hardening elastic-plastic element respectively. In view of this, the strength criterion of the structured soils was established based on the BMM, and the programming of finite element modeling (FEM) for solving the Biot consolidation problem was coded. By comparisons of the simulated results of the natural slopes with initial stress-induced anisotropy and initial isotropy, it was demonstrated that the safety factor of the natural slopes with initial stress-induced anisotropy is higher than the other. By introducing the strength criterion of structured soils with initial stress-induced anisotropy to FEM for solving the Biot consolidation problem, the development of the damage zone in the process of calculating was shown, which reflected good engineering applicability and provided a new idea to evaluate the natural slope stability for the damage zone connected as the standard of slope failure.关键词：structured soils;the Binary Medium Model（BMM）;FEM;anisotropy;natural slope
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发布时间：2023-11-14 - 摘要：Abstract:When high-water-material is applied in deep goaf to control ground settlement, the physical and mechanical properties of the material, especially its long-term mechanical and deformation characteristics, can not only directly affect the activity rhythm of roof and floor, but also control the effect of ground settlement of goaf. To simulating the real filling situation of goaf, triaxial creep test of high-water-material under real water environment was conducted and the creep characteristics was analyzed. Research results showed that: Water environment is conducive to keep and development of strength of high-water-material, and water pressure environment can improve the bearing capacity and long-term strength of the material; Water pressure environment can inhibit creep variable development of the material, and the limit creep variable on Stable creep stage of the material is decrease with the increase of the water pressure. Water pressure environment has significantly effect on initial strain rate and time length of stable creep stage.关键词：real water environment;high-water-material;water pressure;triaxial creep test;creep characteristics
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发布时间：2023-11-14 - 摘要：Abstract:To study on the size effects on the strength of cohesionless coarse-grained soils under the direct shear condition, direct shear tests with the same specimen size were carried out for cohesionless coarse-grained soils with different maximum grain sizes. The maximum grain sizes were 40mm、20mm、10mm、5mm , and 2mm, respectively. There was the same void construction for soils with self-similar fractal structure in mass. The method of tin wires embedded vertically in specimens was used to measure the thickness of shear zones. Test results show that the shear strength and shear zone thickness increased with the increase in the maximum grain size. The size effect on strength were apparent when the maximum grain size is greater than 1/20 of the specimen height. The interlocking force and friction angle decreased with the increase in the logarithm of the ratio of specimen height to maximum grain size, the relationships between them being linear. The strong force chain took place easily because the number of particles in shear zone decreased with the increasing of the maximum grain size, it causing the size effect on strength of cohesionless coarse-grained soils under the direct shear condition.关键词：cohesionless soil;size effect;shear test;shear bands;strength
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发布时间：2023-11-14 - 摘要：Abstract:: In order to study the uncoordinated deformation of different rocks in the salt cavern of China, the conventional uniaxial loading test and Multi-level load creep test on pure rock salt and Salt mud were carried out by using large-scale programmable rheometer of Sichuan University. Based on the tests, the differences of mechanical characteristics between pure rock salt and Salt mud were studied. The results show that the plastic deformation ability and rheological property of salt rock are obviously stronger than salt bearing mudstone. The instantaneous strain generated by loading stress firstly decreased and then increased. Both rocks damaged with the shear characteristic under the condition of long-term creep test, which was different from rocks with the tension damage under the conventional uniaxial. The steady creep rate of salt rock was obviously higher than that of salt bearing mudstone in the same stress percentage and both are exponential function of growth, and the sensitivity of the salt stress is stronger than the salt bearing mudstone. The long-term strength of two kinds of rock was analyzed by using the stress-strain curve inflection point method. The long-term strength of salt rock was 12MPa, which was 48% of short-term compressive strength. The long-term strength of salt bearing mudstone was 34~36MPa, which was lower by 30% than the short-term compressive strength. The ratio of long-term strength and short-term compressive strength of salt rock was much lower than that of most rocks.关键词：bedded salt rock;Uniaxial creep;mechanical properties;long-term strength
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发布时间：2023-11-14 - 摘要：Abstract:According to the fierce underground press and bench convergence in shallow seam mining, taking Shendong mining area as an research object，the roof strata moving law in shallow thin bedrock was studied with 3D simulation experiment. The dimension of the simulation model was 1050mm×2000mm×1130mm; the model tests were conducted with a geometrical scale of 1∶100,a gravimetric scale of 1:1.67, a temporal scale of 1:10, and a stress scale of 1:1.67. The monitoring was conducted on the surface displacement and roof strata move. The results showed that: there were only caving zone and fractured zone in the roof strata during mining; the immediate roof kept caving as long as mining; the first weighting interval was 40m, the periodic weighting distance was 20m; there were procreant crannies reaching the earth's surface, clearly side stepped subsidence, sand bursting in the area of cut and terminal mining line, and collapse pits in the the surface; the roof strata move was mainly vertical displacement, and increased along with the mining; the bridge leaded to the roof strata move smaller near the coal pillar than far away the coal pillar; there were notable positive correlation between roof strata move and surface displacement, but the surface displacement was smaller and hysteretic to the roof strata move, and was affected by the sand bursting.
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发布时间：2023-11-14 - 摘要：Abstract:To study the effect of confining pressure on acoustic emission characteristics of rock salt in the process of loading, a series of triaxial compression tests were carried out on MTS815 Flex Test GT rock mechanics test system and PCI-2 acoustic emission(AE) monitoring system under different confining pressures. The results showed: AE locations、counting rate and energy rate had good consistency. High counting rate、high energy rate and the agglomeration of AE locations lagged with the confining pressure increasing. Under low confining pressure, the failure of rock salt was shear failure. High counting rate, high energy rate and the agglomeration of AE locations occurred mainly in the yield stage period. Under high confining pressure, rock salt had the large plastic deformation characteristics. High counting rate、high energy rate and the agglomeration of AE locations occurred mainly in the peak stage and after peak stage. With the confining pressure increasing, the cumulative counts and the quantity of AE locations declined; the maximum energy rate and total energy decreased with the confining pressure increasing,5MPa were about 43 times and 22 times of 30MPa.关键词：triaxial compression;rock salt;acoustic emission;AE energy;AE count;AE locations
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发布时间：2023-11-14 - 摘要：Abstract:The researching on the effect of the crack’s inclined angle to the mixed-mode fracture properties of the semi-circular bending (SCB) specimen is presented. A series of experiments were conducted by SCB specimens containing an edge crack and subjected to three-point-bending loads. Sichuan black sandstones were used to make the SCB specimens, and the ABAQUS, a finite element numerical analysis soft-ware, was employed to calculate the mixed-mode fracture toughness. Comparing the results of experiments with the results calculated from several fracture criteria, one could find out the criteria which was suitable for the mixed-mode fracture of the black sandstone. The results showed that the stress intensity factor (SIF) KI decreased, whereas the KII and the T-stress increased as the inclined angle increasing. Meanwhile, the test results agreed well with the improved R-criterion, which showed that the improved R-criterion was accurate and reliable on the black sandstone SCB experiments.关键词：semi-circular bend specimen;mixed mode rock fracture;stress intensity factor;fracture criteria
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发布时间：2023-11-14 - 摘要：Abstract:Splitting testings on 48 100mm×100mm×100mm concrete specimens combined by two parts were conducted to figure out efficient methods to improve the interfacial bonding behavior between existing concrete and attached concrete during retrofitting. The attaching concrete was incorporated with 4 different kinds of fibers, which were stell fiber, polyacrylonitrile fiber, basalt fiber and carbon nano-tube. The effects on bonding behavior due to different fiber and proportion were investigated to find out the best one. It was showed that the bonding behavior was improved when the attaching concrete incorporated with fiber. Those incorporated with carbon nano-tube performed best, the following one was polyacrylonitrile fiber, and then basalt fiber and steel fiber in order. Furthermore, splitting testings on 192 extra specimens, in which the attaching parts were incorporated with fiber and styrene-acrylic emulsion, were carried out to study the interfacing bonding behavior. The effects due to different fibers, content of styrene-acrylic emulsion and proportion of fibers were evaluated according the testing results. Anyway, incorporating styrene-acrylic emulsion to the attached concrete generally showed better performance than those without styrene-acrylic emulsion. The best content proportion for both fibers and styrene-acrylic emulsion was pointed out according to the testing results.关键词：stell fiber;polyacrylonitrile fiber;basalt fiber;carbon nano-tube;styrene-acrylic emulsion;bonding;splitting tensile
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发布时间：2023-11-14 - 摘要：Abstract:The indoor and outdoor surface temperature and convection velocity of a double layer glass curtain wall in Chengdu were tested in situ, the variation of temperature along the horizontal and vertical direction and how it changed with time were obtained. Then using both the field boundary conditions and JGJ/T 151-2008 boundary conditions, 2D steady heat transfer models were established on THERM7, U value of the glass panel and frames were obtained respectively. By comparison, the difference of the glass panel U value is 2.2%, while the difference of frame U value is 12.9%. The influence of glass emissivity and filling gas on the thermal performance of the glass curtain wall was studied with WINDOW7.
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发布时间：2023-11-14 - 摘要：Abstract:Abstract:To make a better choice about the energy dissipation forms for the arch dam downstream,the hydraulics indicators of three forms were compared in this paper. The test results showed that under the scheme of the long apron, the flow regime was poor, the baseplate and revetment was unstable; that under the scheme of the water cushion pond and second dams, the flow regime and hydraulics indexes met the requirements, however, the hydraulic optimization of water cushion pond was complex and the cost ofsecond dam was high; that under the scheme of the short apron, the position and depth of scouring pit were within the scope of the permit, but it could harm the security and stability of the arch dam for the geological conditions of factors. Based on the test results, the scope of the short apron can be determined preliminarily. Thus, combined with the test results, engineering experience, geological conditions and project cost，the first choice for scheme of downstream energy dissipation was short apron scheme.关键词：medium arch dam;energy dissipation and erosion prevention;apron;cushion pool
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发布时间：2023-11-14 - 摘要：Abstract:The traditional slice interpolation algorithm is not sensitive to unusual data points, while the deformation vector field based underutilized shortcomings. In order to solve the problem in the medical establishment and analysis of 3D models, we proposed a new slice interpolation method .First introduced in image registration methods to get deformation field between adjacent sequences. Firstly, taking into account the registration in different directions will get different deformation field, we will fuse the two fields to get the information richer deformation field. Secondly, we will get the displacement vector set registration between images by deformation field, and use cubic spline interpolation to get the gray value set gray value at displacement vector ends. Thirdly, using the linear relationship between the displacement vectors and interpolation layer to get the gray in intersection. Finally, using the thin plate spline surface fitting to give the gray value of the image coordinate system. Experimental results show that the algorithm proposed by this paper compared with other algorithms, image quality is better.关键词：Registration;Interpolation;Surface Fitting
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发布时间：2023-11-14 - 摘要：Abstract:In order to improve the correct recognition rate for poor quality iris images, a sectored-based method for iris recognition was proposed. Not like the conventional recognition method, the algorithm divided the iris image into different sectors, recognized different sectors separately and combined their results using Bayesian fusion based on sparsity concentration index value. The low-rank matrix of each sector was selected as iris feature, and sparse representation based classification was used as classifier. Because different regions of the iris had different qualities, the algorithm can reduced the impact of poor quality regions on the recognition result. Experiment results on CASIA-Iris-Interval and IIT Delhi V1 iris database showed that the proposed algorithm achieved better correct recognition rate and had strong robustness for poor quality iris images. The studies of the number of sectors and training images demonstrated that, eight of the sector number was suggested and a test iris image could be well represented by seven training image from the same class.关键词：Biometrics technologies;Iris recognition;Low-rank matrix;SRC;Bayesian fusion
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发布时间：2023-11-14 - 摘要：Abstract:Vibro-acoustography has been influenced by multipath reflection interference, that lead to the advanced elasticity imaging method is difficult to applied to clinical, and the related algorithm for multipath mitigation has been unable to break through. In view of this，simulation software of Vibro-acoustography has been designed, to help the algorithm research to solve the multipath interference. The most difficulty is how to fast and accurately calculate the multiple reflection paths. In this paper, the improved Cyrus-Beck algorithm was used to determine the intersection points of the boundaries and the wave propagation track, which can make the calculation of the wave tracing more effectively, and programming to greatly reduced the amount of code. As the results, the simulation software can simulate the Vibro-acoustography effectively, and the received signal can better reflect the multipath reflection, and software provides a important way to solve the multipath interference. Comparing with the acquisition of physical experiments by Greenleaf teem, software's validity was proved.关键词：Vibro-acoustography;multipath reverberation;the Cyrus-Beck algorithm;wave tracing
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发布时间：2023-11-14 - 摘要：Abstract:In order to improve the estimation accuracy, a new method based on deep convolutional neural networks is proposed in this paper to automatically learn effective features and conduct classification for head pose estimation. First, a DCNN is designed and fulfilled, making use of DCNN’s capability of nonlinear mapping and feature representation learning. Then, a classifier is trained based on the learned feature representations for the purpose of head pose estimation. Experimental results on the Pointing’04 and FacePix databases show that our designed DCNN can learn features automatically and efficiently for effective head pose estimation. The mean absolute errors on the two databases are 4.05〫and 2.24〫, separately. The proposed DCNN based method outperforms existing hand-craft feature based methods in terms of both estimation accuracy and robustness.关键词：deep convolutional neural networks;head pose estimation;classification
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发布时间：2023-11-14 - 摘要：Abstract:In order to locate a moving target with a single observer receiving signals from multiple illuminators, with the time differences of arrival (TDOAs) and frequency differences of arrival (FDOAs) between direct signals and target echoes as measurements, Taylor iterative method is used to estimate the target position and velocity. The initial iteration value is given by a least squares (LS) algorithm. The Cramer-Rao lower bound (CRLB) and the theoretical error of the proposed algorithm are also derived. Simulation results show that the proposed algorithm needs merely one iteration to converge to the global optimal solution. The CRLB of jointing TDOA and FDOA location system is lower that of the TDOA-only and FDOA-only system. Moreover, the proposed algorithm achieves the CRLB at moderate noise level before the threshold effect occurs. From the Geometric Dilution of Precision (GDOP) figure, we conclude target position and illuminator position are also important factors affecting the localization accuracy.关键词：single-observer;passive location;TDOA;FDOA;Taylor series;least squares
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发布时间：2023-11-14 - 摘要：Abstract:In order to solve the electric vehicles scale prediction problem of lack of historical data and professional method, this paper is motivated to present a scale evolution algorithm which can help to measure the development of electric vehicles with considering multiple parameters. By employing the system dynamics theory, the presented theory is able to establish an effective model which is further used in the analysis of the development of electric vehicles. In the simulation, a number of important parameters have been studied including policy，subsidy，charge price，and so on, key factors in the three stages, i.e. “demonstration promotion, rapid growth and steady development”, are analyzed by sensitivity verification. The simulation results indicate that the evolution of electric vehicles scale would grow upward fast in future, while the purchasing ratio would be shown as S type curve, in which the change in the early stage would be affected by the government policies, while the development of technology and infrastructure construction will become the most critical factors in the later stage.关键词：electric vehicle;system dynamics;model
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发布时间：2023-11-14 - 摘要：Abstract:Rotating bending fatigue tests were performed to evaluate the very high cycle fatigue properties of ultra-supercritical turbine CrMoW rotor steel at room temperature and 600 ℃. The microstructure of specimen before and after fatigue loading was examined extensively by TEM. Additional, the surface and fracture morphology was observed by SEM. The results showed that an inflexion point of S-N curves could be discovered clearly at fatigue life of 5×106 cycles at room temperature. While at 600 ℃, the S-N curve presented a continuously descending shape. The microstructure after fatigue at high temperature was still martensitic, but the martensitic lath were slipped, merged and fragmented; the density of dislocations decreased and the main carbides in the steel were considerably coarsened and coagulated with adjacent carbides, and some carbides became spherical. Accordingly, from the result of SEM, the properties of fatigue were reduced because of appearance of the oxidation film. The fatigue fracture mainly occurred at the surface of specimen at both of temperatures. The inclusions were observed in the crack initiation area at 600 ℃ and the crack initiation resulted from interaction with crack initiating at surface and inclusion at subsurface.
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发布时间：2023-11-14 - 摘要：Abstract:The densification behaviors of copper (Cu) powders with a average particle size of 0.5μm and 30μm by multi-physics fields coupling sintering were investigated respectively and compared with densification behavior of Cu powders of mixed particle sizes. The sintering test was carried out using a Gleeble-1500D thermal simulation instrument. The effects of minor addition of coarse copper powder (30μm) to fine copper powder (0.5μm) on sintering densification process was also discussed. It is found the relative densities of the compact produced using fine copper powders (0.5μm) and powders of different particle sizes (0.5, 30μm) are higher than the relative density of the compact fabricated using coarse copper powder (30μm). The highest relative density obtained is 94.61% for compact using powders of different particle sizes as the starting material. The results indicate that densification process of the fine powders may be hindered during the sintering process due to their poor electrical conductivity and more dense sample are likely to be produced using Cu powders of different sizes.关键词：multi-physics fields coupling sintering;fine copper powder;densification
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发布时间：2023-11-14 - 摘要：Abstract:The influence organizational performance of tempering temperature on CB2 heat resistant steel were studied by OM, SEM and other equipments. The results showed that，When keeping the quenching temperature (1100)，quenching time (1h) and tempering time(2h) invariant. The tempering temperature had a significant influence on microstructure and properties of CB2 heat resistant steel. On the whole, with tempering temperature rising, the tensile strength, yield strength and hardness, increased at first and then decreased. But elongation were falling before rising trend. The microstructure was ideal when heat treatment was quenching (1100℃x1h) + the first tempering (730℃x2h) + second tempering(720℃x2h).Its second phase was fine and compact, it had grain size and granular shape, and it had the comprehensive mechanics performance .It was uniformly dispersed in lath martensite grain boundaries. CB2 heat steel had comprehensive mechanical properties after the heat treatment process .So chose it as the optimization of heat treatment process of CB2 heat resistant steel.关键词：ZG12Cr9Mo1Co1NiVNbNB Heat Resistant Steel,Tempering Temperature,Microstructure,Mechanical properties
- 1378
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- 2
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发布时间：2023-11-14 - 摘要：Abstract:A three-dimensional mathematical model for the metal hydride reactor incorporating spiral coil tube was proposed. The specialty of the model was that it had coupled the effects of the variation of heat transfer fluid temperature on the hydrogen adsorption rate. The newly established model was solved using multi-physics software and the heat transfer performance and the hydrogen adsorption reaction characteristics under various operating conditions were investigated. The results showed that hydrogen adsorption reaction could be divided into three stages. In the first stage, hydrogen pressure was a major influence. In the third stage, the reaction was mainly under the control of the heat transfer process. And the second stage was a transition phase. As hydrogen pressure decreased, the reaction rate and the average bed temperature reduced. When the pressure decreased to 0.6MPa, the reaction rate reduced significantly. As the temperature of heat-transfer fluid increased, the temperature difference decreased, leading to reducing of reaction rate. When the temperature increased to 323K, the reaction was not complete and the reaction rate reduced remarkably. In the bed, the temperature in places near spiral coil tube was low and the reaction was completely finished. However, the heat transfer performance in places far away from spiral coil tube was relatively poor and the reaction was pretty slow. Therefore, there was a direction to improve the heat transfer structure.关键词：metal hydride;reactor;helical coil heat exchanger;heat transfer;reaction rate
- 1678
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- 18
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发布时间：2023-11-14 - 摘要：Abstract:In order to efficiently reuse high titanium blast furnace slag, foam glass-ceramics were produced by simultaneously foaming and crystallizing process at 1000 C, using the slag and waste glass as main raw materials, AlN as foaming agent, borax Na2B4O7•5H2O as fluxing agent. The influence of the additive amount of Na2B4O7•5H2O (4~7wt.%) on the foam glass-ceramics was studied by XRD, SEM and the test of physical and mechanical performance. The results showed that the borax barely affected the crystal phases of the foam glass-ceramics, only different kinds of pyroxene evolving, meaning converting from diposide, hedenbergite, omphacite to augite; With increasing the borax amount, the system softened and the cell wall became compacting. Consequently, the porosity increased, the bulk density, compressive strength and heat conductivity decreased. The optimum comprehensive property of foam glass-ceramics was achieved at 5wt.% fluxing agent.关键词：high titanium blast furnace slag;foam glass-ceramics;fluxing agent;AlN
- 1471
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- 2
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发布时间：2023-11-14 - 摘要：Abstract:Solutions of the dimethyl phthalate (DMP) of pH 3.0 have been treated with ozone and ozonation catalyzed with hydroxylamine sulfate (HAS). The influence of hydroxyl radical (•OH) inhibitor tert-butyl alcohol (TBA) pH on the decomposition of O3 were also investigated. The results indicated that the degradation rate of DMP in O3/HAS system was improved by 82.58% compared with that of ozonation alone. In the presence of TBA, the removal rate of DMP is significantly decreased in O3/HAS system, due to •OH rapidly consumed by TBA. Ozone decomposition is obviously accelerated with the increased of HAS concentration at pHs ranging from 3.0 to 9.2. Besides, hydroxylamine hydrochloride (HAC) and hydroxylamine phosphate (HAP) have been chosen to investigate the effect of hydroxylamine species on ozonation. It is shown that O3/HAS、O3/HAC、O3/HAP processes have promote the elimination of DMP.关键词：ozone, hydroxylamine, dimethyl phthalate, hydroxyl radical, degradation
- 1694
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- 2
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发布时间：2023-11-14 - 摘要：Abstract:Methyl Orange was used as target for exploring the catalytic ability of Fe-MnOx. In the experiment, the factors of calcination temperature (300°C, 400°C, 500°C, 600°C and 700°C) and doping ratio of Fe/Mn (Fe/Mn=1/3, Fe/Mn=1/1 and Fe/Mn=1/3) were studying to determine the optimal catalyst preparation condition. The Fe-MnOx with the highest catalytic ability was characterized by XPS, XRD, SEM and BET. The result showed that Fe-MnOx, prepared under the conditions of 400°C calcination temperature and Fe/Mn=1/1, exhibited the highest catalytic, after 20min reaction, the degradation of Methyl Orange was 70.26%, which increased by 32.29% when compared with that in the sole ozonation. With addition of Tert-butano(TBA), the degradation of Methyl Orange was inhibited partly, which indicated that the reaction mechanism not only involved of the hydroxyl radical reaction mechanism, but also involved of other reaction mechanism. In order to further understand the intrinsic relationship between catalytic activity and internal structure of the catalyst, the Fe-MnOx with best catalytic activity was characterized by XPS, TEM, XRD and BET, which indicates that the Fe-MnOx consisted of Fe2O3, FeO(OH), MnO2 and Mn5O8.Besides, the catalyst was in uncertain crystal and evacuated structure, corresponding to an big specific surface area of 117.81 m2/g.
- 1424
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- 4
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发布时间：2023-11-14
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