最新刊期
卷 48 ， 期 Z2 ， 2016
- 摘要：Abstract:Wetting-drying cycling is a common water-soil interaction mode; it plays an important role in the strength and deformation of rock and soil and the stability of landslide. Based on the analysis of the basic characteristics of the slip soil of silt and silty clay, this paper studies on the deformation evolution and strength weakening characteristic of different types of slip soil under the effect of wetting-drying cycle through the indoor dry- wet cycling test and direct shear test. The research results show that in the state of air dried, the deformation behavior of silty soil of slip soil crack in the internal of soil, and with the increase of cycle number, the cracks continue expansion and widening, then the cracks close after saturation; on the other hand, the volume of silty clay is shrinking in air dried condition and expanding after saturation. The strength weakening of the two kinds of slip soil present the same rules under the effect of wetting-drying cycling, the degree of strength weakening is largest at the first cycle of dry and wet, and the strength reaches a certain value after the third cycle. As for shear strength parameters of the two types of slip soil, the reduction of the cohesion in a logarithmic curve form with cycle number, and the angle of internal friction in a linear form with cycle number. Finally, this paper analyzes the sensitivity and significant of the shear strength parameters, we can found that the shear strength of slip soil decrease is mainly due to the lower of cohesive force under the effect of wetting-drying, compared with the internal friction angle, cohesion is affected by the dry-wet circulation is more significant.关键词：wetting-drying cycle;slip soil;deformation evolution;shear strength;cohesion;internal friction angle
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发布时间：2023-11-14 - 摘要：Abstract: To study the influence of confining pressure for mechanical properties and failure mechanics model on limestone, triaxial compression tests of intact limestone samples are carried out by MTS815.Based on the macroscopic failure forms, the tension and shear failure model is built and relative formula between the peak strength and confining pressure is established. Influence on the shear strength parameters (cohesion and internal friction angle) made by both of the tension and shear model and pure shear model is dicussed.The results show that elastic modulus, compressive strength and residual strength for samples increases with confining pressure increasing, and the relationship between residual strength and confining pressure is nonlinear. The ratio between hoop strain and axial strain reduces under negative exponent with confining pressure increasing when samples damaged final.Within the scope of a certain confining pressure, rock compressive strength are affected by shear strength parameters and tensile strength. The rock shear strength parameters determined by Tension and shear model increase with the rupture Angle increasing. Compared with the pure shear model, the value is smaller. Therefore, considering the rock failure model under low confining pressure has some practical significance.关键词：confining pressure;mechanical property;mechanical model;cohesion;internal friction angle
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发布时间：2023-11-14 - 摘要：Abstract:In order to solve hydraulic problems such as low pressure, cavitation, etc in high velocity bending duct .This paper was based on the Kajiwa hydropower station ecological flow discharge duct, used model test, numerical simulation and theoretical analysis method to find out the influence of outlet area on the wall pressure and flow cavitation number in high speed bending duct. The experimental results showed that: When the outlet area was large, pressure in the bending duct is low. In high water head, the bending duct's flow cavitation number is lower than the cavitation incipient number; When diminished the outlet size to 81.6% of the original area, under different water head, cavitation number of the bending duct increased 2 ~ 4 times, made the duct 's cavitation number higher than the cavitation incipient number in different water head; Based on the energy equation, theoretical method for calculating the cavitation number of the bending duct flow was obtained, the calculated results were in good agreement with those obtained in the model test and numerical simulation.关键词：bending duct;wall pressure;cavitation;cavitation number;numerical simulation
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发布时间：2023-11-14 - 摘要：Abstract:The Jinping I high arch dam has great height and large library, its overall stability of the dam and foundation is a prominent problem due to the complex geological conditions in the dam site area. After the impounding and operation of project, the strength of abutment structure surface and weak rock will drop due to the long-term effects of high stress and strong osmotic pressure, which is more adverse to the overall stability of the dam. In order to evaluate the engineering safety after reinforcement, the weakening rate of the weak structure strength under different conditions were obtained by the water-rock coupling triaxial test. On this basis, the geological mechanics model test with synthetic method has been conducted. Due to test technical limitations, it is temporarily unable to decrease the strength of fracture zone and influenced zone separately on structural planes. Considering the factors, the weakening scheme with a average weakening rate 30% of fracture zone was conducted at last in model test. In order to explore the influence of weakening effect of weak structural plane strength to overall stability, 3D nonlinear finite element calculation and analysis has been done, one strength reduction program is a average weakening rate 30% of fracture zone ( scheme 1) , and the other is to decrease the strength of fracture zone and influenced zone separately (scheme 2). Comparing the calculation results with the two schemes, under normal operating conditions, displacements of the dam of scheme two is greater than scheme one about -0.2%~2.24% , abutment displacement value is greater than scheme one about -2.35%~1.72%,and displacements of the dam is greater than scheme one about -4.68%~9.23% under overload conditions. The displacement of dam and abutment resistance body, failure process and mechanism of the two schemes are similar, the numerical values are basically the same, the test and calculation results are similar. For model test of Jinping I high arch dam, using the plan which concentrately reducing the strength 30% of broken zone to imitate the plan which reducing the strength of broken zone and the influenced zone separately can be considered as according with the actual situation and reasonably practicable, its test results are reliable.
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发布时间：2023-11-14 - 摘要：Abstract:To research the evolution of thermodynamic process in large reservoirs, a prototype observation of Pubugou Reservoir was carried out from April 2012 to May 2013. Based on the observed data, the changes of the water temperature structure in different seasons and the thermodynamic relations between the upstream and downstream of the dam site were illustrated by using comparison and statistical analysis. The results showed that the isotherms of the water temperature stratification were horizontal. A double-thermocline phenomenon in the vertical temperature profiles appeared in front of the dam during high temperature period, and cold water submergence appeared in the tail area in winter. Compared with the natural process at the dam site, the outflow temperature exhibited obvious homogenization effect and delay effect with the biggest drop of 1.7℃ in April and the biggest rise of 3.3℃ in December. Because the outflow was from deep layer, good stability was found in the daily process of the outflow temperature, and suction was detected on the water column stratification in front of the intake.关键词：prototype observation;water temperature stratification;double thermocline;temperature density flow;hydraulic suction
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发布时间：2023-11-14 - 摘要：Abstract:In order to get full use of the reservoirs under the condition of ensuring the safety of flood control, the basic principle of calculating the flood specified for management based on the total probability formula was expounded in this paper. It also put forward the actual method of calculating the flood specified for management based on the total probability formula when there is little data or the flood characteristics of the pre-flood seasons and the post-flood seasons are same roughly. In the case of Mabian hydrologic station,the results showed that the flood specified for management calculated by the total probability formula not only can reach the flood control standard,but also can help the reservoir to maximize the benefits.关键词：The flood specified for management;The total probability formula;Flood control standard
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发布时间：2023-11-14 - 摘要：Abstract:In order to determine the seismic performance of a embankment dam, relying on indoor dynamic triaxial apparatus to carry out a lot of power performance testing studied on dam shell material, core material and fault material. Based on Hardin-Drnevich model to determine the dynamic elastic modulus and damping ratio parameters of soil samples. When the dynamic strain within the range of 10-6 to 10-5, dynamic modulus and confining pressure, consolidation ratio was positively correlated. With the increase of dynamic modulus, the correlation is reduced. Proposing a relationship of dynamic strain and vibration level fitted exponential model, then verify isobaric fault consolidated material. Find that different confining pressure, consolidation ratio of core material strain - vibration level curve have same consistent trend, while dam shell material is more discrete. Confining pressure has a more significant influence in comparison with consolidation ratio.
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发布时间：2023-11-14 - 摘要：Abstract:Abstract:For the mathematical model was used in power station intake problem of long period of riverbed evoluti- on, resulting in the low calculation efficiency and low accuracy of defects. In this paper adopt the combination of implicit and explicit algorithm ,explored sedimentation Characteristics of long period of time,established the long period of water and sediment mathematical model can simulate riverbed evolution,and applide the model to Zhao Hua power plant,s sediment deposition.The comparison results of water intake,s water level and flow rate with physical model and mathematical model under different frequency flood, showed that the mathematical model could better simulate the flow characteristic of water intake. By predict under lasha scheme and not lasha ,scheme power plant running years of riverbed evolution,the results showed that the mathematical model for simulation results was similar with the actual engineering, complied with objective rules,could better simulate the river sediment problems.关键词：Water inlet;riverbed evolution;sediment deposition;algorithm
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发布时间：2023-11-14 - 摘要：Abstract:In allusion to the security risk of Hefei metro tunnel engineering during shield construction traversing adjacently under existing urban tunnel,adopting FLAC3D to simulate shield tunnel excavation, stress and strain distribution rules of the existing urban tunnel and shield tunnel during shield construction were analyzed. Research showed that: when shield machine before was processing before and after monitoring section in 10m ,the vertical displacement of urban tunnel and arch sedimentation were effected observably, urban tunnel settlement deformation of monitoring stations in the upper of shield tunnel and the centre of shield tunnels was large;tensile stress appeared in the south north of the bottom of the urban tunnel , the maximum tensile stress was 1.088MPa.After the excavation, the maximum uplift displacement of soil around the shield tunnel was 6.22 mm, the maximum subsidence was 4.96 mm;the distribution regularity of displacement of surrounding soil of two shield tunnel was similar.The protective construction measures were put forward according to results, the subsidence values measured were below the warning value, law of simulation results and measured results was similar,the simulation achieved good effect.关键词：shield tunnel;traverse adjacently under tunnel;deformation;stress
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发布时间：2023-11-14 - 摘要：Abstract:The dam abutment rock mass stability is one of the important reasons for accidents of arch dams that are under complicated geological conditions. A hydropower arch dam located in some area of complicated topographic and geological conditions, there are concentrated alteration zones developed closing to the right dam abutment, and along these zones several faults developed. Apart from that, on the different heights of its left abutment, some faults developed as well. In order to study the stability of the arch dam abutment rock mass, a 3-dimension finite element model is built based on the topography and geology of the dam site with taking into full account of the adverse geologic structure factors such as the abutment's practical geological, the major faults and the alteration zone. 3-dimension nonlinear finite element method is applied to simulate the stress filed of arch dam and rock mass in dam site under normal operating conditions with temperature drop. Whether the rock mass is reinforced or not, the stability of dam abutment is analysed by point safety factor method, and the abutment ultimate bearing capacity is simulated by synthesis method. The results show that the value of point safety factor of abutment rock is within a reasonable range and relatively high, synthesis safety factor is relatively large, suggesting that arch dam body is reasonable, reinforcement measures are rational and effective, and the abutment ultimate bearing capacity is relatively strong.关键词：arch dam;stability of abutment;nonlinear finite element;point safety factor;synthesis method
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发布时间：2023-11-14 - 摘要：Abstract:To study AE characteristics and failure precursors during full-regime failure process of coal，unloading experiments on AE characteristics of coal samples under different initial confining pressures were carried out with the MTS815 Rock Mechanics and the PCI-2 AE Monitoring System. The results indicated that the bearing capacities got improved significantly with the increasing of confining pressure. The AE space-time evolution, energy releasing characteristics and amplitude distribution were well corresponding to timely mechanical states. Several parameters presented obvious mutations during the unloading process: the two mutational points of AE space evolution were respectively 55% and 80% of peak strength, the mutational point of energy rate corresponded to 87% stress level, the mutational point of ring count rate approximately corresponded to the peak strength, and the amplitude and b value were respectively corresponding to 89% and 78% of post-peak stress. These mutational points were divided into four groups as the precursor information of the coal’s unloading failure, which can provide references for the AE monitoring technology in the prevention of dynamic disasters during excavation.关键词：rock mechanics;coal;unloading;acoustic emission;failure precursors
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发布时间：2023-11-14 - 摘要：Abstract:In order to control the deformation of roadway with crushing overlying strata effectively, support technology of joist steel shed is used according to the overburden rock characteristics. The forming principle of arch structure is analyzed and the critical width of roadway is determined. Aiming at the characteristics of the roadway with its surrounding rock crushing, low strength, anchorless, the equilibrium arc theory is applied and surrounding rock pressure is calculated. The critical width formula is built when the maximum principal stress of steel shed beam is equal to joist steel yield limit. The 106 coal mine taken as an engineering example is analyzed. The results are shown that the critical width of roadway is 4.4m. The roadway critical width can be improved by increasing the supporting strength or reducing the roadway height. The method, reducing shed distance or increasing the steel type, can be used to realize the greater roadway width if needed.关键词：crushing overburden;mining roadway;the equilibrium arc theory;critical width
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发布时间：2023-11-14 - 摘要：Abstract:In order to study the impact of the normal compression on shear (mode II) crack propagation, Sandstone is used to make the unilateral crack specimen. Shear experiment on cracks which are under different normal compression loads was carried out by rock deformation test system. The results show that the normal compression loads play an inhibitory effect on the crack initiation and expansion. With the increase of the normal compression loads, initial crack angle decreases. While, the relationship between the normal compression loads and mode II crack critical stress intensity factor is achieved. The rock mode II crack limit stress intensity factor also increases with the increasing normal compression loads. Compression-shear crack propagation was simulated under different compression loads by using ABAQUS. Meanwhile, Variation law of mode II stress intensity factor in crack tip was obtained with variation of compression loads.关键词：compression load;initial angle;shear crack;stress intensity factor
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发布时间：2023-11-14 - 摘要：Abstract:To study the shear behavior of the bolt connection of prefabricated concrete wallboard, through one-way repeated loading test of the four specimens with concrete prefabricated bolt joint, the hysteresis curves, skeleton curves, the characteristic load and displacement of the specimens were obtained. Furthermore,stiffness degradation and ductility index of the specimen were calculated and analyzed. The results showed that the fabricated bolt connection with good bearing capacity, stiffness and energy dissipation capacity, is a reliable way of dry connection; Through adopting stirrup densification to the weak part and increasing the number of bolts, the shear behavior of prefabricated bolt connection can be significantly improved.关键词：prefabricated concrete wallboard;bolt connection;joint;shear behavior
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发布时间：2023-11-14 - 摘要：Abstract:Abstract: In order to research the effect of equivalent simulation in case of different geological conditions and different overloading coefficients,we used a method combined geomechanical model test with finite element method calculation.By analyzing the gravity dam on homogeneous ground and complicated foundation with weak structural planes, analysing the results of geomechanical model test,the equivalent uplift pressure model and the actual uplift pressere model which used the finite element method calculation to calculate,the feasibility of the equivalent simulation in case of different geological conditions and different overloading coefficients had been verified (here in after referred to as equivalent model and the actual model). The result showed that the equivalent simulation of uplift pressure was able to reach the equivalence of the gravity dam uplift pressure in different case of overloading coefficients on both homogeneous foundation and complicated foundation.So the equivalent simulation of uplift pressure is feasible to be applied togeomechanical model test.关键词：Key Words: uplift pressure;homogeneous ground;complicated foundation;overloading coefficient;equivalent simulation
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发布时间：2023-11-14 - 摘要：Abstract:Segmentation of pore and throat is basis of core microstructure analysis. Because of complexity and diversity of core, Throat segmentation algorithms are always hot and difficult problem in domestic and foreign research. A new algorithm for segmentation of pore and throat based on skeleton was proposed. Firstly, the gradient of 3D image distance transform is calculated for extracting skeleton and cross section. Secondly, some throats with local minimum value of cross section area are detected. Skeleton points with local maximum value of cross section area are treated as center point of pores. Then, pore growth segmentation and throat post-processing are carried out. Experimental results show that the method of proposed has good performance in throat segmentation of 3D images. Finally, this paper put forward an algorithm of extracting throat normal which was verified by experiments.
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发布时间：2023-11-14 - 摘要：Abstract:In order to meet strict requirements of real-time and reality of Simulation System, a rendering algorithm of ocean applied to the earth model is proposed. For real-time, ocean mesh grids are classified into near-view part and far-view part. Moving details of near-view part are computed by using FFT spectrum statistical model and far-view part is simulated by disturbance of Perlin noise, and the near-far transition region is rendered by Alpha Blending; For reality, view-dependent ocean mesh grids are built and can be applied to global navigation by real-time coordinate transformation and color of ocean water is rendered by considering both of real-time illumination and underwater refraction. The experimental results show that the proposed algorithm can be applied to efficient rendering of global ocean, which meets the requirements of real-time and reality.关键词：FFT Perlin noise view-dependent ocean rendering
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发布时间：2023-11-14 - 摘要：Abstract:Aimming at the shape distribution algorithm and statistical characteristic function could not accurately depict the three-dimensional(3D) rock model, a rock shape distribution algorithm was proposed. According to the penetration relationship between the line of two random boundary pixels and target phase, the shape distribution D2 distance histogram was classified into three categories: in, out and united. This three histogram respectively represented the structure of pore and grain. The classified occuring frequency is used to describe the distrubution of pore and grain. Shape feature descriptor was extracted by three histograms. After counting abundant pairs of random boundary pixels, the probability distribution function could be generated. As the last step, the quantization method which was utilized to measure geometrical similarity between each 3D rock models also be suggested. The algorithm was tested on numerous 3D rock samples. The results shown that this algorithm can feasibly extract the geometry feature descriptors from 3D rock models and compared the geometrical similarity between each 3D rock models. The depicting ability of this algorithm is exacter than statistical characteristic function and previous shape distribution.关键词：rock shape distribution;3D rock model;shape feature descriptor;geometrical similarity;shape distribution;statistical characteristic function
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发布时间：2023-11-14 - 摘要：Abstract:In order to solve action recognition system’s efficiency and accuracy in complex environment, an improved method based on local part model and feature pre-processing was proposed. The algorithm based on the bag of features, and local part model was used to extract features. The features were pre-processed through Principal Component Analysis methods, While the local part model of frames in the sampling process was optimized. Experiments carried on two benchmark datasets, respectively named UCF Sports and HMDB51. The results showed that this algorithm has higher efficiency and accuracy than the original in complex environment. Compared with other methods , the proposed algorithm showed more accurate and efficient.关键词：action recognition;local part model;feature pre-processing;bag of features
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发布时间：2023-11-14 - 摘要：Abstract:Considered the influence of airport runway taxiway structures and the proportion of the aircraft type on the taking off and landing space, based on analyzing the operation mode of the runway and taxiway, detailed aircraft rolling and taxiing procedure, defined the size of aircraft cell and evolution rules of speed and position ,an aircraft taxiing cellular automata model was built. The change trends of taking off and landing space and space standard deviation were obtained through computer numerical simulation by setting different values for parameters such as the taxiway location, aircraft type, combination of landing and taking off. The simulation results showed that the taking off space increased with the distance between runway threshold and taxiway increasing. If the taxiway was near the landing aircraft rolling end position, the landing space was minimum. If the distance from the runway threshold to taxiway was 450m-800m, average space for a minimum was 135s. If the distance was 800m-900m, space standard deviation was minimum of 20.9. Compared with situation of 100% medium aircraft, if proportion of small aircraft was 100%, the average space reduced 17.8% and space standard deviation reduced 42.3%. The model quantified the key factors acting the taking off and landing space, such as aircraft type, taxiway location, provided technical support for improving the throughput of airport.关键词：air traffic management;cellular automaton;taking off and landing space;surface operations
- 1912
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发布时间：2023-11-14 - 摘要：Abstract:In order to accelerate traversal performance, this paper presents a traversal order algorithm based on an improved cost model by exploiting actual ray distribution. Ray distribution information is sampled in a fast manner without any pre-computation process. Then, the algorithm uses the ray information to estimate traversal cost accurately. A contribution value for each voxel is also computed. Additionally, with the visibility of nodes, traversal orders are evaluated for nodes in an on-demand strategy to reduce overhead further. For scene with 75% occluded shadow rays, it can reduce intersection tests by 61%. These result data shows by exploiting ray distribution, the algorithm can improve traversal performance for shadow ray.关键词：ray tracing;ray sampling;shadows;traversal order
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发布时间：2023-11-14 - 摘要：Abstract:In order to recognize the Named Entity in micro-blog, according to the characteristics of micro-blog, which include non-standard language, much noise, updated quickly, more acronyms and the large amount of data, a method based on the deep learning is proposed in this paper. We trained an AutoEncoder network by a large number of untagged micro-blog data to get abstract characteristics firstly. And then, these features were input into the deep learning network. Finally, the word in sentence would be tagged. In the process of training AutoEncoder network, rather than moving window, periodic convolution method was used to obtain long rely on the information in the sentence. The experiment results on Sina-weibo show that deep learning method can effectively improve the effect of named entity recognition in micro-blog, which illustrated the effectiveness of the proposed method.关键词：Micro-blog;deep learning;Auto coder;Convolution;Named entity recognition
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发布时间：2023-11-14 - 摘要：Abstract:Starting from operational characteristics, in this paper, the operational characteristics localization of zero-pole subsystem of Oustaloup was analyzed based on order-frequency and phase-frequency characteristic function. Thus the Oustaloup rational approximation was studied quantitatively, thereby understand its mathematical principle. Theoretical analysis and numerical calculation results show that, by using the order-frequency and phase-frequency characteristic function, it's a relatively simple and intuitive process to analyze Oustaloup rational approximation, of which its frequency response approximate well and has lower complexity. By adjusting the parameters and , the design can be optimized. These conclusions, not only provides a solid theoretical foundation of mathematics for the understanding, design and optimization of Oustaloup fractance approximation circuits, but also provides a theoretical basis for the design of fractional order controllers (especially optimization).关键词：Oustaloup rational approximation;order-frequency function;approximation error;optimal design
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发布时间：2023-11-14 - 摘要：Abstract:For the stability of gas film thickness and multistage regulation operating conditions leading to failure in dry gas seal, the dynamic characteristics of dry gas seal with spiral groove were analyzed based on Workbench. A model of axial vibration of a floating ring (static ring) was established and the expression of axial vibration amplitude was derived. Workbench was applied to finish prestressed modal analysis and harmonic response analysis of the floating ring system under working conditions. The simulation was compared with the results of theoretical derivation. The change trend of axial vibration amplitude of the floating ring was concluded under same parameters with different values and the main and minor factors affecting the axial vibration amplitude of the floating ring were distinguished. This approach not only can obtain the values of the amplitude of floating ring under different conditions flexibly, but also explain the trend of vibration from the relationship between vibration frequency and inherent frequency.关键词：static ring system;Workbench simulation;prestressed modal analysis;harmonic response analysis
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发布时间：2023-11-14 - 摘要：Abstract:Abstract: The PSO algorithm can optimize the parameters of SVR which is used to predict the metal content in lubricating oil of aero engine. In order to solve the problem of particles may step in the local optimal which occur as the iterative is in progress, a method was proposed. Establish scattering model to relocate these particles, then escape the area of local optimal. Coefficient p was used to adjust the inertia parameter w to speed up algorithm convergence. Experiment shows that particles can step out from the area of local optimal and speed up convergence, improve forecast accuracy.关键词：metal content prediction;algorithm of particles swarm;local optimal;scattering model;relaxation coefficient
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发布时间：2023-11-14 - 摘要：Abstract:Aiming at the shortage of repairing broken parts with spreading powder roller in existing 3D printing equipment, a novel coaxial feeding nozzle with a combination of sending powder and glue simultaneously was proposed in this paper. First of all, the structure of coaxial feeding nozzle was designed. Next, the mathematical model of powder flow concentration and mixed flow speed was established and the changes of powder flow concentration and mixed flow speed along axial direction at fixed flow velocity and flow rate were analyzed. And on the basis of gas-solid two-phase flow theory, the Euler-Lagrange model is set up for coupling calculation of the carrier to send powder nozzle gas-solid mixing flow, obtaining the effect of different powder particle material on the characteristic parameters. Comparing with two results, the results of mathematical model were the same with the Euler-Lagrange model. Gas flow rate, powder amount affect and the characteristics of particles mainly affected powder flow concentration and transmission speed and influenced focus length a little while focus length was mainly influenced by feeding channel angle and gas circulation channel width. Obtaining the parameters of particles provides the theoretical guide for optimizing the structure of coaxial feeding nozzle and manufacturing parameters.关键词：three dimensional printing;coaxial powder feeding;numerical analysis;gas-solid two-phase flow;Euler-Lagrange model
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发布时间：2023-11-14 - 摘要：Abstract:The three-dimensional (3D) elastohydrodynamic lubrication (EHL) model of the involute helical gears was developed by simplifying the contact between tooth surfaces in the mesh of a pair of helical gears into a infinite line-contact lubrication problem. The time-varying contact parameters of helical gears such as the variations of radius of curvature and tangential surface velocities in the mesh were considered in the analysis model. Based on the unified Reynolds equation approach，the transient solutions of the entire meshing process were obtained for a pair of teeth with consideration of real 3D roughness surface. The effects of smooth and rough machining surfaces on the film thickness and pressure distribution during tooth engagement are discussed , and it reveals the microscopic EHL characteristics of two kinds of machined surface. The results show that rough surface has a significant effect on gear lubrication condition, especially in the process of the gear tooth out of engagement , which serious reduce the lubricating film thickness between the gear tooth with lubricating conditions become bad. High precision surface roughness make the high ratio of film thickness of the contact surface, the small contact area and load, therefore lubrication get excellent.关键词：helical gear;mixed elastohydrodynamic lubrication;infinite line contacts;roughness surface
- 1940
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发布时间：2023-11-14 - 摘要：Abstract:CaO/Al2O3 composite adsorbents with various CaO contents were prepared via impregnation method. The structure and surface properties of the adsorbents were characterized by CO2-TPD, XRD, N2 adsorption/desorption and FT-IR techniques. The adsorbent adsorption performance was investigated under different pressures at 25 oC and 70 oC, respectively. The results showed that the composite adsorbents can reacted with CO2 to form calcium carbonate, and the adsorbent 5%CaO/95%Al2O3 had the highest adsorption amount of 36.45 mg/g at 70 oC and 1.0 MPa. Furthermore, the heat of adsorption was calculated by using D-R equation and the enthalpy changes of adsorption against adsorbate surface loading was studied by using Clausius-Clapeyron equation, and it presented that the adsorption heat increased as the CaO content increased, while the enthalpy decreased as the surface loading of the adsorbent increased.关键词：CO2;Al2O3-based;modification;thermodynamics
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发布时间：2023-11-14 - 摘要：Abstract:Heat pipe was the most useful heat transfer component for electronic equipment. It had high heat transfer performance compared with the pure metal. While the wicks in heat pipe was the key structure to determine the performance. In this paper cupric oxalate was used as pore former which could increase the porosity of the wicks, and avoid introduce impurity. Besides the influce of cupric oxalate content on porosity, permeability of the wicks and the heat transfer performance of heat pipe was studied. The results showed that with the increase of the content of cupric oxalate, the wicks porosity, the maximum heat transfer power(Qmax) and temperature difference increased. When the same cupric oxalate content was added, higher Qmax of heat pipe manufactured by irregular copper power was got higher than spherical, while thermal homogeneity is inferior to spherical. Furthermore, by controlling the working fluid content, we concluded the relationship between the filling factor and the Qmax. When the working fluid was 80%, the maximum heat transfer power of the heat pipe could be got the maximum, which is the best working state.关键词：cupric oxalate;heat pipe;porisity;thermal performance;working fluids
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发布时间：2023-11-14 - 摘要：Abstract:Varied texturing surface were manufactured in tested plates surface though laser etching technology. The tribology performance of nano-diesel soot (DS) as a lubricant additive on the textured surface was investigated in the UTM- tribometer with a ball against plate contact model. The tribological results were analyzed by the HR-TEM, 3D-profiler, SEM and Raman spectroscopy analysis method. The results showed that friction coefficient increased due to the micro-texture, but the materials wear loss obviously decreased. The higher area ratio, the samples showed a better anti-wear performance. The adding of diesel soot contributed significantly reduced the friction and wear. This was attributed to the self-lubricity property of the diesel soot and the storage function of the micro-texture. By the combined action of surface texture and diesel soot additive illustrated an excellent anti-wear property.关键词：Texture;Nano-particles;Oil lubrication;Friction and wear
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发布时间：2023-11-14 - 摘要：Abstract:In order to explore the effect of shape of magnetic refrigerants on magnetic cooling performance, the numerical investigation of three types of magnetic regenerators (the circular channel regenerator, the rectangular channel regenerator and the parallel-plate regenerator) was done in this paper. The regenerator composed of parallel plates with porosity 0.3 performed better than the other regenerators. Under the optimal parallel-plate regenerator obtained above, the regenerator with plate thickness of 0.3mm showed better performance when frequency was 0.5Hz. The zero temperature span cooling capacity was about 200W and the coefficient of performance was about 3.3 when the utilization was 3.0. The regenerator with thinner plates showed better cooling performance when the operating frequency was higher (above 0.5Hz), while the effect of plate thickness wasn’t so obvious below the frequency of 0.5Hz. The cooling capacity was almost inversely proportional to the temperature span, and the cooling capacity of 21W with temperature span of 4K and cooling capacity of 5W with temperature span of 16K were obtained. The temperature span increased with the increase of the hot end temperature.关键词：magnetic refrigeration;active magnetic regenerator;utilization;numerical investigation;cooling performance
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发布时间：2023-11-14
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