Most of the existing studies on tunnel blast wave are based on spherical or grouped charges, however,conventional weapons are mostly cylindrical rather than spherical. In order to analyze the impact of cylindrical cha...Most of the existing studies on tunnel blast wave are based on spherical or grouped charges, however,conventional weapons are mostly cylindrical rather than spherical. In order to analyze the impact of cylindrical charges on the tunnel blast wave loads and to develop a quantitative calculation method, this study carried out experimental and numerical research. Initially, external explosion experiments were conducted using both 35 kg spherical charges and cylindrical charges with aspect ratio of 4.8 at two different distances from the tunnel entrance. Comparative analysis of the blast wave parameters in the tunnel revealed that the explosive equivalent of the cylindrical charges was significantly higher than that of the spherical charges. To address this, an equivalent coefficient κ based on the spherical charges was proposed for the cylindrical charges. Subsequently, numerical simulations were conducted for the experimental conditions, and the numerical simulation results match the experiments well. Through numerical calculations, the reliability of the equivalent coefficient κ under the experimental conditions was verified, and comparison analysis indicated that the explosion energy of cylindrical charges spreads more radially, resulting in more explosion energy entering the tunnel, which is the fundamental reason for the increase in tunnel blast wave loads. Additionally, analyzing the explosion energy ratio entering the tunnel is an effective method for calculating the equivalent coefficient κ. Finally, through more than one hundred sets of numerical calculation results, the impact of the proportional distance λ and the ratio of charge mass to the tunnel cross-section dimension φ on the equivalence coefficients κ was investigated. An empirical formula for the equivalence coefficient κ was derived through fitting, and the accuracy of the formula was validated through literature experimental results. The research findings of this paper will provide valuable guidance for the calculation of blast wave loads in tunnel.展开更多
-The chief purpose of the research was to understand the physiological function change regularity, performance and adaptability of the human body living and working under high pressure for prolonged time.In January 19...-The chief purpose of the research was to understand the physiological function change regularity, performance and adaptability of the human body living and working under high pressure for prolonged time.In January 1989, 4 naval divers entered the habital of NMRI's 500 msw saturation diving system after a series of adaptive diving training. The breathing mixture was helium-oxygen. After 55 h compression (including intermediate stages) the 350 msw depth was reached, where the divers lived and worked for 72 h 10 min. No sign of discomfort or significant HPNS was found in the 4 divers.The second and third day of the saturation exposure, the divers carried out 370 msw dry and wet chamber excursion diving 2 man-time each, the divers effectively carried out operational work under water, the total excursion time was 1 h each excursion dive.Saturation decompression started after 3-day storage exposure, the divers were gradually brought toward the surface 25 msw a day on the average by employing the linear steady rate of decompression. During decompression, no case of DCS occurred. Immediate post-dive medical check-ups shows that they were physically normal.More than 120 biomedical indices were monitored and measured on the divers at different period of the experiment. The organisms showed a good adaptability and certain operating capability, and both the compression and decompression profiles were proved to be satisfactory.The detailed experimental data obtained provided sound scientific basis for the practical application of future great depth open sea saturation diving.展开更多
Bottom water coning is the main reason to reduce the recovery of horizontal bottom water reservoir. By water coning, we mean the oil-water interface changes from a horizontal state to a mound-shaped cone and breaks th...Bottom water coning is the main reason to reduce the recovery of horizontal bottom water reservoir. By water coning, we mean the oil-water interface changes from a horizontal state to a mound-shaped cone and breaks through to the wellbore. Autonomous inflow control device(AICD) is an important instrument maintain normal production after bottom water coning, however, the resistance increasing ability of the swirl type AICD is insufficient at present, which seriously affects the water control effect. Aiming this problem, this paper designs a multi-stage resistance-increasing and composite type AICD. The separation mechanism of oil-water two phases in this structure, the resistance form of oil-water single phase and the resistance-increasing principle of water phase are analyzed. Establishing the dual-phase multi-stage separation and resistance-increasing model, and verified by measuring the throttling pressure drop and oil-water volume fraction of the AICD, it is found that the composite type AICD has the effect of ICD and AICD at the same time, which can balance the production rate of each well section at the initial stage of production, delay the occurrence of bottom water coning. In the middle and later stages of production, water-blocking can be effectively increased to achieve water control and stable production.After structural sensitivity analysis, the influence law of various structural parameters on the water control performance of composite AICD was obtained. The simulation calculation results show that,compared with the existing swirl type AICD, composite AICD has higher sensitivity to moisture content,the water phase throttling pressure drop is increased by 4.5 times on average. The composite AICD is suitable for the entire stage of horizontal well production.展开更多
Virtual simulation experiment,as a new way to promote the digital transformation of education,has a broad development prospect and application value.The civil engineering experimental volume and space are huge,it has ...Virtual simulation experiment,as a new way to promote the digital transformation of education,has a broad development prospect and application value.The civil engineering experimental volume and space are huge,it has a long construction period,is highly dangerous,and is difficult to experiment with.In order to solve the contradiction between the traditional theory teaching of civil engineering and the engineering training of students,the construction of virtual simulation experimental teaching courses with a high degree of realism,intuition,and accuracy can be used as a useful supplement and innovation of experimental and practical teaching.This paper takes the virtual simulation experimental teaching course of urban overpasses as an example,introduces the necessity and practicability of the course construction,and describes the experimental principle structure of the course,the simulation scene design,the experimental teaching process,the experimental method,etc.The course has achieved good application results,and it has been recognized as the first-class virtual simulation teaching course of the Chongqing Municipal Government,which provides certain references to the construction of the same type of courses in the civil engineering profession.展开更多
This paper proposes a method for creating a three-dimensional(above-ground and underground)fracture network in deep coalbed methane(CBM)reservoirs,which is the directional fracturing by slotted hydraulic blasting in u...This paper proposes a method for creating a three-dimensional(above-ground and underground)fracture network in deep coalbed methane(CBM)reservoirs,which is the directional fracturing by slotted hydraulic blasting in underground drilling.First,theoretical analysis was conducted to explain the mechanism by which the slotted borehole enables the separation and incidence of explosive shock wave at the slot tip,resulting in the superposition of two sub-stress waves to cause directional fracture and damage to the rock.Then,LS-DYNA was used to simulate the process of directional fracturing by slotted hydraulic blasting to verify the theoretical mechanism.Finally,similar simulation experiments were performed on traditional blasting and slotted hydraulic blasting to confirm the directional fracturing effect of the proposed method.The results indicate that the slotted hydraulic blasting method can predominate the fracture orientation under formation stress,creating extensive directional fractures in rocks in the slot direction.This study is supplemental to the efforts on directional fracturing of rocks and provides a new approach for efficient exploitation of CBM.展开更多
With the rapid development of information technology and the increasing complexity of the financial market,the teaching methods and means of the Securities Investment course in universities are facing new challenges a...With the rapid development of information technology and the increasing complexity of the financial market,the teaching methods and means of the Securities Investment course in universities are facing new challenges and opportunities.The purpose of this paper is to discuss the application and construction path of virtual simulation experimental teaching in the Securities Investment course.Firstly,it analyses the problems existing in the teaching of traditional securities investment courses,such as the disconnection between theory and practice and the single teaching mode.In order to solve these problems,this paper puts forward the necessity of introducing virtual simulation experimental teaching and details the specific application path of virtual simulation experimental teaching in the Securities Investment course.展开更多
Injection-production coupling(IPC) technology holds substantial potential for boosting oil recovery and enhancing economic efficiency.Despite this potential,discussion on gas injection coupling,especially in relation ...Injection-production coupling(IPC) technology holds substantial potential for boosting oil recovery and enhancing economic efficiency.Despite this potential,discussion on gas injection coupling,especially in relation to microscopic mechanisms,remains relatively sparse.This study utilizes microscopic visualization experiments to investigate the mechanisms of residual oil mobilization under various IPC scenarios,complemented by mechanical analysis at different stages.The research quantitatively assesses the degree of microscopic oil recovery and the distribution of residual oil across different injection-production methods.Findings reveal that during the initial phase of continuous gas injection(CGI),the process closely mimics miscible displacement,gradually transitioning to immiscible displacement as CO_(2)extraction progresses.Compared to CGI,the asynchronous injection-production(AIP) method improved the microscopic oil recovery rate by 6.58%.This enhancement is mainly attributed to significant variations in the pressure field in the AIP method,which facilitate the mobilization of columnar and porous re sidual oil.Furthermo re,the synchronous cycle injection(SCI) method increased microscopic oil recovery by 13.77% and 7.19% compared to CGI and AIP,respectively.In the SCI method,membrane oil displays filame ntary and Karman vo rtex street flow patterns.The dissolved and expanded crude oil te nds to accumulate and grow at the oil-solid interface due to adhesive forces,thereby reducing migration resistance.The study findings provide a theoretical foundation for improving oil recovery in lowpermeability reservoirs.展开更多
Taking deep coal-rock gas in the Yulin and Daning-Jixian areas of the Ordos Basin,NW China,as the research object,full-diameter coal rock samples with different cleat/fracture development degrees from the Carboniferou...Taking deep coal-rock gas in the Yulin and Daning-Jixian areas of the Ordos Basin,NW China,as the research object,full-diameter coal rock samples with different cleat/fracture development degrees from the Carboniferous Benxi Formation were selected to conduct physical simulation and isotope monitoring experiments of the full-life-cycle depletion development of coal-rock gas.Based on the experimental results,a dual-medium carbon isotope fractionation(CIF)model coupling cleats/fractures and matrix pores was constructed,and an evaluation method for free gas production patterns was established to elucidate the carbon isotope fractionation mechanism and adsorbed/free gas production characteristics during deep coal-rock gas development.The results show that the deep coal-rock gas development process exhibits a three-stage carbon isotope fractionation pattern:“Stable(Ⅰ)→Decrease(Ⅱ)→Increase(Ⅲ)”.A rapid decline in boundary pressure in stageⅢleads to fluctuations in isotope value,characterized by a“rapid decrease followed by continued increase”,with free gas being produced first and long-term supply of adsorbed gas.The CIF model can effectively match measured gas pressure,cumulative gas production,and δ^(13)C_(1) value of produced gas.During the first two stages of isotope fractionation,free gas dominated cumulative production.During the mid-late stages of slow depletion production,the staged pressure control development method can effectively increase the gas recovery.The production of adsorbed gas is primarily controlled by the rock's adsorption capacity and the presence of secondary flow channels.Effectively enhancing the recovery of adsorbed gas during the late stage remains crucial for maintaining stable production and improving the ultimate recovery factor of deep coal-rock gas.展开更多
To address the challenges in studying the pore formation and evolution processes,and unclear preservation mechanisms of deep to ultra-deep carbonate rocks,a high-temperature and high-pressure visualization simulation ...To address the challenges in studying the pore formation and evolution processes,and unclear preservation mechanisms of deep to ultra-deep carbonate rocks,a high-temperature and high-pressure visualization simulation experimental device was developed for ultra-deep carbonate reservoirs.Carbonate rock samples from the Sichuan Basin and Tarim Basin were used to simulate the dissolution-precipitation process of deep to ultra-deep carbonate reservoirs in an analogous geological setting.This unit comprises four core modules:an ultra-high temperature,high pressure triaxial stress core holder module(temperature higher than 300°C,pressure higher than 150 MPa),a multi-stage continuous flow module with temperature-pressure regulation,an ultra-high temperature-pressure sapphire window cell and an in-situ high-temperature-pressure fluid property measurement module and real-time ultra-high temperature-pressure permeability detection module.The new experimental device was used for simulation experiment,the geological insights were obtained in three aspects.First,the pore-throat structure of carbonate is controlled by lithology and initial pore-throat structure,and fluid type,concentration and dissolution duration determine the degree of dissolution.The dissolution process exhibits two evolution patterns.The dissolution scale is positively correlated to the temperature and pressure,and the pore-forming peak period aligns well with the hydrocarbon generation peak period.Second,the dissolution potential of dolomite in an open flow system is greater than that of limestone,and secondary dissolved pores formed continuously are controlled by the type and concentration of acidic fluids and the initial physical properties.These pores predominantly distribute along pre-existing pore/fracture zones.Third,in a nearly closed diagenetic system,after the chemical reaction between acidic fluids and carbonate rock reaches saturation and dynamic equilibrium,the pore structure no longer changes,keeping pre-existing pores well-preserved.These findings have important guiding significance for the evaluation of pore-throat structure and development potential of deep to ultra-deep carbonate reservoirs,and the prediction of main controlling factors and distribution of high-quality carbonate reservoirs.展开更多
In this study,the hydraulic behavior and sand transport efficiency of the siphon automatic sand discharge device were studied by software simulation tests.By simulating the actual situation,this study analyzed how fac...In this study,the hydraulic behavior and sand transport efficiency of the siphon automatic sand discharge device were studied by software simulation tests.By simulating the actual situation,this study analyzed how factors such as the difference in water level,sediment concentration,and pipeline layout affected the sediment discharge effect.The results show that the sediment discharge device can effectively discharge sediment under diverse operating conditions and show adaptability to different environmental conditions,which indicates that it is suitable for various types of reservoir environments.展开更多
Thiadiamondoids(TDs)have recently attracted increasing attention as molecular proxies for thermochemical sulfate reduction(TSR)reactions in reservoirs.However,their formation mechanisms,as well as the generation and e...Thiadiamondoids(TDs)have recently attracted increasing attention as molecular proxies for thermochemical sulfate reduction(TSR)reactions in reservoirs.However,their formation mechanisms,as well as the generation and evolution processes,remain poorly understood.In this study,simulation experiments with a duration of 160 h were conducted on the model compound 1,3-dimethyladamantane(1,3-DMA)using the CaSO_(4),MgSO_(4),and elemental S systems,with measurements at the 10th,20th,40th,80th and 160th hours during the simulation process being presented.The results indicate that at the end of simulation,the MgSO_(4) system exhibited the lowest residual amounts of 1,3-DMA,suggesting the highest degree of TSR.Four types of non-hydrocarbon compounds with adamantane structures were detected in the liquid products in the three experiment systems:adamantanones,adamantanols,adamantanethiols(ATs),and thiaadamantanes(TAs).Among these,adamantanones exhibited the highest concentrations in the three simulation systems.In addition,TAs were dominated by C_(3)-TAs in the CaSO_(4) and MgSO_(4) systems and by C_(2)-TAs in the elemental S system.The simulation experiments revealed a strong correlation between the concentrations of TAs and adamantanones,suggesting that adamantanones might be the intermediates for TAs.Combined with the synthesis mechanism of TAs from thiaadamamantane-4,8-dione,TDs might have two different genetic mechanisms:(a)low temperature cationic carbon ion rearrangement from diagenesis to early catagenesis stage,and(b)a free sulfur radical mechanism in high-temperature TSR process during middle-late catagenesis.TAs exhibited different generation and evolution processes across different experiment systems.Notably,the MgSO_(4) system revealed that TAs undergo generation,accumulation,and destruction process,corresponding to Easy%Ro values of 0.89%-0.98%,0.98%-1.21%,and>1.21%,respectively.Among these three simulation systems,dibenzothiophenes(DBTs)concentrations consistently trended upwards,indicating TAs have lower thermal stability than DBTs.展开更多
The coal-bearing source rocks in the Jurassic Shuixigou Group have received widespread attention as the primary source rocks in the Turpan-Hami Basin of China,but the hydrocarbon generation potential and process of th...The coal-bearing source rocks in the Jurassic Shuixigou Group have received widespread attention as the primary source rocks in the Turpan-Hami Basin of China,but the hydrocarbon generation potential and process of the mudstone in the Shuixigou Group,especially the mudstone at the top of the Sangonghe Formation,are unclear.Taking the source rocks of the Xishanyao Formation and the Sangonghe Formation as objectives,this study conducted rock pyrolysis and gold tube simulation experiment to investigate their hydrocarbon generation characteristics and differences.Our results indicate that the source rocks of the Xishanyao Formation include mudstone,carbonaceous mudstone and coal,and the quality of the source rocks is highly heterogeneous;the source rocks of the Sangonghe Formation are mainly composed of mudstone,and it is a good gas source rock.Simulation experiments found that the activation energy required for the generation of gaseous hydrocarbons by the mudstone of the Sangonghe Formation is lower than that by the mudstone of the Xishanyao Formation.The hydrocarbon generation process can be divided into three stages for both formations,but the gas generation potential of the Xishanyao Formation mudstone is higher than that of the Sangonghe Formation mudstone.A large amount of hydrocarbon was generated by the mudstone of the Xishanyao Formation when entering late thermal evolution,of which methane is dominant,mainly from the demethylation reaction of mature kerogen.On the other hand,a large amount of hydrocarbon was generated by the mudstone of the Sangonghe Formation in the early stage of thermal evolution,of which light hydrocarbon and wet gas are dominant,mainly from the early cracking stage of kerogen.This difference may be attributed to the structure of kerogen.The mudstone of the Xishanyao Formation is conducive to the formation of highly mature dry gas reservoirs,while the mudstone of the Sangonghe Formation is conducive to the formation of low maturity condensate gas and volatile oil reservoirs.The research result provides a scientific basis for the comparison of oil and gas sources and the evaluation of oil and gas resources in the Turpan-Hami Basin.展开更多
In the ultra-deep strata of the Tarim Basin,the vertical growth process of strike-slip faults remains unclear,and the vertical distribution of fractured-cavity carbonate reservoirs is complex.This paper investigates t...In the ultra-deep strata of the Tarim Basin,the vertical growth process of strike-slip faults remains unclear,and the vertical distribution of fractured-cavity carbonate reservoirs is complex.This paper investigates the vertical growth process of strike-slip faults through field outcrop observations in the Keping area,interpretation of seismic data from the Fuman Oilfield,Tarim Basim,NW China,and structural physical simulation experiments.The results are obtained mainly in four aspects.First,field outcrops and ultra-deep seismic profiles indicate a three-layer structure within the strike-slip fault,consisting of fault core,fracture zone and primary rock.The fault core can be classified into three parts vertically:fracture-cavity unit,fault clay and breccia zone.The distribution of fracture-cavity units demonstrates a distinct pattern of vertical stratification,owing to the structural characteristics and growth process of the slip-strike fault.Second,the ultra-deep seismic profiles show multiple fracture-cavity units in the strike-slip fault zone.These units can be classified into four types:top fractured,middle connected,deep terminated,and intra-layer fractured.Third,structural physical simulation experiments and ultra-deep seismic data interpretation reveal that the strike-slip faults have evolved vertically in three stages:segmental rupture,vertical growth,and connection and extension.The particle image velocimetry detection demonstrates that the initial fracture of the fault zone occurred at the top or bottom and then evolved into cavities gradually along with the fault growth,accompanied by the emergence of new fractures in the middle part of the strata,which subsequently connected with the deep and shallow cavities to form a complete fault zone.Fourth,the ultra-deep carbonate strata primarily develop three types of fractured-cavity reservoirs:flower-shaped fracture,large and deep fault and staggered overlap.The first two types are larger in size with better reservoir conditions,suggesting a significant exploration potential.展开更多
The mechanism of fracture initiation is the basic issue for hydraulic fracture technology. Because of the huge differences in fracture initiation mechanisms for different reservoirs,some successful fracturing techniqu...The mechanism of fracture initiation is the basic issue for hydraulic fracture technology. Because of the huge differences in fracture initiation mechanisms for different reservoirs,some successful fracturing techniques applied to porosity reservoirs are ineffectual for fractured reservoirs.Laboratory tests using a process simulation device were performed to confirm the characteristics of fracture initiation and propagation in different reservoirs.The influences of crustal stress field,confining pressure,and natural fractures on the fracture initiation and propagation are discussed.Experimental results demonstrate that stress concentration around the hole would significantly increase the fracture pressure of the rock.At the same time,natural fractures in the borehole wall would eliminate the stress concentration,which leads to a decrease in the fracture initiation pressure.展开更多
A simulated experimental reduction of and the synthesis of uraninite by a sulfate-reducing bacteria, Desulfovibrio desulfuricans DSM 642, are first reported. The simulated physicochemical experimental conditions were:...A simulated experimental reduction of and the synthesis of uraninite by a sulfate-reducing bacteria, Desulfovibrio desulfuricans DSM 642, are first reported. The simulated physicochemical experimental conditions were: 35°C, pH=7.0-7.4, corresponding to the environments of formation of the sandstone-hosted interlayer oxidation-zone type uranium deposits in Xinjiang, NW China. Uraninite was formed on the surface of the host bacteria after a one-week's incubation. Therefore, sulfate-reducing bacteria, which existed extensively in Jurassic sandstone-producing environments, might have participated in the biomineralization of this uranium deposit. There is an important difference in the order- disorder of the crystalline structure between the uraninite produced by Desulfovibrio desulfuricans and naturally occurring uraninite. Long time and slow precipitation and growth of uraninite in the geological environment might have resulted in larger uraninite crystals, with uraninite nanocrystals arranged in order, whereas the experimentally produced uraninite is composed of unordered uraninite nanocrystals which, in contrast, result from the short time span of formation and rapid precipitation and growth of uraninite. The discovery has important implications for understanding genetic significance in mineralogy, and also indicates that in-situ bioremediation of U-contaminated environments and use of biotechnology in the treatment of radioactive liquid waste is being contemplated.展开更多
Experiments simulating the effect of coal mine stopping through a fault zone were designed based on a working face of the Qianqiu coal mine in Yima, China. Through simulation of the physical process of fault reactivat...Experiments simulating the effect of coal mine stopping through a fault zone were designed based on a working face of the Qianqiu coal mine in Yima, China. Through simulation of the physical process of fault reactivation and coal bumps, the displacement of the surrounding strata and evolution characteristics of fault stress under the effect of mining were studied. The mechanism of fault reactivation induced by coal mining was analyzed. The results show that shortly before fault reactiva- tion, the normal stress and shear stress increased rapidly and the risk of a fault slip occurring was also increased. The fault reac- tivation, caused by the mining activity, occurred when the working face was 25-35 m from the fault along the hanging wall. The influence of mining increased the possibility of fault reactivation, while the local failure of the bearing capacity of the working face was the direct cause of the fault slip. Our results indicate that the influence of fault slip on the coal of the working face had a transient impact and acted as a loading-unloading function.展开更多
It＇s very important to simulate impact load of debris flow effectively and to investigate dynamic response of architectures under dynamic impact of debris flow, which are necessary to design disaster mitigation const...It＇s very important to simulate impact load of debris flow effectively and to investigate dynamic response of architectures under dynamic impact of debris flow, which are necessary to design disaster mitigation construction. Firstly, reinforced concrete domestic architectures in mountain areas of western China had been chosen as main architecture style. The bearing load style and the destructed shape of reinforced flamed construction impacted by discontinuous viscous debris flow were studied systematically. Secondly, Jiangjia Ravine debris flow valley in Yunnan Province, China had been chosen as research region. Utilizing based data from fieldwork and practical survey, the authors simulated and calculated theoretically impact force of discontinuous viscous debris flow. Thirdly, an impact data collecting system （IMHE IDCS） was designed and developed to fulfill designed simulation experiments. Finally, a series of impact test of researched structure models had been fulfilled. During experiment, the destructed shape and course of models were observed and the dynamic displacement data and main natural frequency data of models were collected and analyzed.展开更多
Gas leakage is an important consideration in natural systems that experience gas hydrate accumulation.A number of velocity models have been created to study hydrate-bearing sediments,including the BGTL theory,the weig...Gas leakage is an important consideration in natural systems that experience gas hydrate accumulation.A number of velocity models have been created to study hydrate-bearing sediments,including the BGTL theory,the weighted equation,the Wood equation,the K-T equation,and the effective medium theory.In previous work,we regarded water as the pore fluid,which meant its density and bulk modulus values were those of water.This approach ignores the presence of gas,which results in a biased calculation of the pore fluid's bulk modulus and density.To take into account the effect of gas on the elastic wave velocity,it is necessary to recalculate the bulk modulus and density of an equivalent medium.Thus,a high-pressure reactor device for simulating leakage systems was developed to establish the relationship between wave velocity and hydrate saturation in methane-flux mode.A comparison of the values calculated by the velocity model with the experimental data obtained in this study indicates that the effective medium theory(EMT,which considers gas effects)is more applicable than other models.For hydrate saturations of 10%–30%,the result ranges between EMT-B(homogenous gas distribution)and EMT-B(patchy gas distribution).For hydrate saturations of 30%–60%,the results are similar to those of the EMT-B(homogenous gas distribution)mode,whereas hydrate saturations of 60%–70%yield results similar to those of the EMT-A mode.For hydrate saturations greater than 80%,the experimental results are similar to those of the EMT-B mode.These results have significance for hydrate exploitation in the South China Sea.展开更多
In order to obtain satisfactory mechanical properties for the cam used in high-power ship diesel engines, a new quenching technology was proposed by designing a two-stage quenching process with an alkaline bath as the...In order to obtain satisfactory mechanical properties for the cam used in high-power ship diesel engines, a new quenching technology was proposed by designing a two-stage quenching process with an alkaline bath as the quenching medium. To demonstrate the effectiveness of the proposed new quenching technology, both numerical analysis and experimental study were performed. The new quenching technology was analyzed using finite element method. The combined effects of the temperature, stress and microstructure fields were investigated considering nonlinear material properties. Finally, an experimental study was performed to verify the effectiveness of the proposed new quenching technology. The numerical results show that internal stress is affected by both thermal stress and transformation stress. In addition, the direction of the internal stress is changed several times due to thermal interaction and microstructure evolution during the quenching process. The experimental results show that the proposed new quenching technology significantly improves the mechanical properties and microstructures of the cam. The tensile strength, the impact resistance and the hardness value of the cam by the proposed new quenching technology are improved by 4.3%, 8.9% and 3.5% compared with those by the traditional quenching technology. Moreover, the residual stress and cam shape deformation are reduced by 40.0% and 48.9% respectively for the cam manufactured by the new quenching technology.展开更多
The paper deals with the design and experimental validation of the actuation mechanism control system for a morphing wing model.The experimental morphable wing model manufactured in this project is a full-size scale w...The paper deals with the design and experimental validation of the actuation mechanism control system for a morphing wing model.The experimental morphable wing model manufactured in this project is a full-size scale wing tip for a real aircraft equipped with an aileron.The morphing actuation of the model is based on a mechanism with four similar in house designed and manufactured actuators,positioned inside the wing on two parallel lines.Each of the four actuators used a BrushLess Direct Current(BLDC)electric motor integrated with a mechanical part performing the conversion of the angular displacements into linear displacements.The following have been chosen as successive steps in the design of the actuator control system:(A)Mathematical and software modelling of the actuator;(B)Design of the control system architecture and tuning using Internal Model Control(IMC)methodology;(C)Numerical simulation of the controlled actuator and its testing on bench and wind tunnel.The morphing wing experimental model is tested both at the laboratory level,with no airflow,to evaluate the components integration and the whole system functioning,but also in the wind tunnel,in the presence of airflow,to evaluate its behavior and the aerodynamic gain.展开更多
文摘Most of the existing studies on tunnel blast wave are based on spherical or grouped charges, however,conventional weapons are mostly cylindrical rather than spherical. In order to analyze the impact of cylindrical charges on the tunnel blast wave loads and to develop a quantitative calculation method, this study carried out experimental and numerical research. Initially, external explosion experiments were conducted using both 35 kg spherical charges and cylindrical charges with aspect ratio of 4.8 at two different distances from the tunnel entrance. Comparative analysis of the blast wave parameters in the tunnel revealed that the explosive equivalent of the cylindrical charges was significantly higher than that of the spherical charges. To address this, an equivalent coefficient κ based on the spherical charges was proposed for the cylindrical charges. Subsequently, numerical simulations were conducted for the experimental conditions, and the numerical simulation results match the experiments well. Through numerical calculations, the reliability of the equivalent coefficient κ under the experimental conditions was verified, and comparison analysis indicated that the explosion energy of cylindrical charges spreads more radially, resulting in more explosion energy entering the tunnel, which is the fundamental reason for the increase in tunnel blast wave loads. Additionally, analyzing the explosion energy ratio entering the tunnel is an effective method for calculating the equivalent coefficient κ. Finally, through more than one hundred sets of numerical calculation results, the impact of the proportional distance λ and the ratio of charge mass to the tunnel cross-section dimension φ on the equivalence coefficients κ was investigated. An empirical formula for the equivalence coefficient κ was derived through fitting, and the accuracy of the formula was validated through literature experimental results. The research findings of this paper will provide valuable guidance for the calculation of blast wave loads in tunnel.
文摘-The chief purpose of the research was to understand the physiological function change regularity, performance and adaptability of the human body living and working under high pressure for prolonged time.In January 1989, 4 naval divers entered the habital of NMRI's 500 msw saturation diving system after a series of adaptive diving training. The breathing mixture was helium-oxygen. After 55 h compression (including intermediate stages) the 350 msw depth was reached, where the divers lived and worked for 72 h 10 min. No sign of discomfort or significant HPNS was found in the 4 divers.The second and third day of the saturation exposure, the divers carried out 370 msw dry and wet chamber excursion diving 2 man-time each, the divers effectively carried out operational work under water, the total excursion time was 1 h each excursion dive.Saturation decompression started after 3-day storage exposure, the divers were gradually brought toward the surface 25 msw a day on the average by employing the linear steady rate of decompression. During decompression, no case of DCS occurred. Immediate post-dive medical check-ups shows that they were physically normal.More than 120 biomedical indices were monitored and measured on the divers at different period of the experiment. The organisms showed a good adaptability and certain operating capability, and both the compression and decompression profiles were proved to be satisfactory.The detailed experimental data obtained provided sound scientific basis for the practical application of future great depth open sea saturation diving.
基金supported by National Natural Science Foundation(52204050)Sichuan Science and Technology Program(2021ZHCG0013,22ZDYF3009)。
文摘Bottom water coning is the main reason to reduce the recovery of horizontal bottom water reservoir. By water coning, we mean the oil-water interface changes from a horizontal state to a mound-shaped cone and breaks through to the wellbore. Autonomous inflow control device(AICD) is an important instrument maintain normal production after bottom water coning, however, the resistance increasing ability of the swirl type AICD is insufficient at present, which seriously affects the water control effect. Aiming this problem, this paper designs a multi-stage resistance-increasing and composite type AICD. The separation mechanism of oil-water two phases in this structure, the resistance form of oil-water single phase and the resistance-increasing principle of water phase are analyzed. Establishing the dual-phase multi-stage separation and resistance-increasing model, and verified by measuring the throttling pressure drop and oil-water volume fraction of the AICD, it is found that the composite type AICD has the effect of ICD and AICD at the same time, which can balance the production rate of each well section at the initial stage of production, delay the occurrence of bottom water coning. In the middle and later stages of production, water-blocking can be effectively increased to achieve water control and stable production.After structural sensitivity analysis, the influence law of various structural parameters on the water control performance of composite AICD was obtained. The simulation calculation results show that,compared with the existing swirl type AICD, composite AICD has higher sensitivity to moisture content,the water phase throttling pressure drop is increased by 4.5 times on average. The composite AICD is suitable for the entire stage of horizontal well production.
基金Chongqing Institute of Technology’s 2022 Virtual Simulation Experiment“Golden Course”Construction Project“Virtual Simulation Experiment of Urban Overpass Vehicle Passage”2023 Teaching Method Reform and“Information Technology+”Smart Teaching Special Research Project Information Technology Multi-Dimensional Research Results of“Enabling Virtual Simulation Experiment Smart Teaching Reform and Practice”。
文摘Virtual simulation experiment,as a new way to promote the digital transformation of education,has a broad development prospect and application value.The civil engineering experimental volume and space are huge,it has a long construction period,is highly dangerous,and is difficult to experiment with.In order to solve the contradiction between the traditional theory teaching of civil engineering and the engineering training of students,the construction of virtual simulation experimental teaching courses with a high degree of realism,intuition,and accuracy can be used as a useful supplement and innovation of experimental and practical teaching.This paper takes the virtual simulation experimental teaching course of urban overpasses as an example,introduces the necessity and practicability of the course construction,and describes the experimental principle structure of the course,the simulation scene design,the experimental teaching process,the experimental method,etc.The course has achieved good application results,and it has been recognized as the first-class virtual simulation teaching course of the Chongqing Municipal Government,which provides certain references to the construction of the same type of courses in the civil engineering profession.
基金supported by the Science and Technology Department of Guizhou Province Fund(Qiankehe Basic-ZK[2023]Normal-446 and Qiankehe Basic-ZK[2023]Normal-445)Liupanshui Science and Technology Bureau Fund(52020-2022-PT-15)the Education Department of Guizhou Province Fund(Youth Science and Technology Talent Development Project Qianjiaoji[2024]150).
文摘This paper proposes a method for creating a three-dimensional(above-ground and underground)fracture network in deep coalbed methane(CBM)reservoirs,which is the directional fracturing by slotted hydraulic blasting in underground drilling.First,theoretical analysis was conducted to explain the mechanism by which the slotted borehole enables the separation and incidence of explosive shock wave at the slot tip,resulting in the superposition of two sub-stress waves to cause directional fracture and damage to the rock.Then,LS-DYNA was used to simulate the process of directional fracturing by slotted hydraulic blasting to verify the theoretical mechanism.Finally,similar simulation experiments were performed on traditional blasting and slotted hydraulic blasting to confirm the directional fracturing effect of the proposed method.The results indicate that the slotted hydraulic blasting method can predominate the fracture orientation under formation stress,creating extensive directional fractures in rocks in the slot direction.This study is supplemental to the efforts on directional fracturing of rocks and provides a new approach for efficient exploitation of CBM.
基金The 2024 Hankou University School-Level Teaching Reform Research Project“Research on the Application of Virtual Simulation Experimental Teaching in the Course of Securities Investment”(Project number:2024JY43)。
文摘With the rapid development of information technology and the increasing complexity of the financial market,the teaching methods and means of the Securities Investment course in universities are facing new challenges and opportunities.The purpose of this paper is to discuss the application and construction path of virtual simulation experimental teaching in the Securities Investment course.Firstly,it analyses the problems existing in the teaching of traditional securities investment courses,such as the disconnection between theory and practice and the single teaching mode.In order to solve these problems,this paper puts forward the necessity of introducing virtual simulation experimental teaching and details the specific application path of virtual simulation experimental teaching in the Securities Investment course.
基金supported by the National Natural Science Foundation of China (Nos.52374064,51974347,52474072)the Shandong Provincial Universities Youth Innovation and Technology Support Program (2022KJ065)。
文摘Injection-production coupling(IPC) technology holds substantial potential for boosting oil recovery and enhancing economic efficiency.Despite this potential,discussion on gas injection coupling,especially in relation to microscopic mechanisms,remains relatively sparse.This study utilizes microscopic visualization experiments to investigate the mechanisms of residual oil mobilization under various IPC scenarios,complemented by mechanical analysis at different stages.The research quantitatively assesses the degree of microscopic oil recovery and the distribution of residual oil across different injection-production methods.Findings reveal that during the initial phase of continuous gas injection(CGI),the process closely mimics miscible displacement,gradually transitioning to immiscible displacement as CO_(2)extraction progresses.Compared to CGI,the asynchronous injection-production(AIP) method improved the microscopic oil recovery rate by 6.58%.This enhancement is mainly attributed to significant variations in the pressure field in the AIP method,which facilitate the mobilization of columnar and porous re sidual oil.Furthermo re,the synchronous cycle injection(SCI) method increased microscopic oil recovery by 13.77% and 7.19% compared to CGI and AIP,respectively.In the SCI method,membrane oil displays filame ntary and Karman vo rtex street flow patterns.The dissolved and expanded crude oil te nds to accumulate and grow at the oil-solid interface due to adhesive forces,thereby reducing migration resistance.The study findings provide a theoretical foundation for improving oil recovery in lowpermeability reservoirs.
基金Youth Fund of National Natural Science Foundation of China(42302170)CNPC Scientific and Technological Innovation Fund(2022DQ02-0104)RIPED Open Project Fund(2024-KFKT-31).
文摘Taking deep coal-rock gas in the Yulin and Daning-Jixian areas of the Ordos Basin,NW China,as the research object,full-diameter coal rock samples with different cleat/fracture development degrees from the Carboniferous Benxi Formation were selected to conduct physical simulation and isotope monitoring experiments of the full-life-cycle depletion development of coal-rock gas.Based on the experimental results,a dual-medium carbon isotope fractionation(CIF)model coupling cleats/fractures and matrix pores was constructed,and an evaluation method for free gas production patterns was established to elucidate the carbon isotope fractionation mechanism and adsorbed/free gas production characteristics during deep coal-rock gas development.The results show that the deep coal-rock gas development process exhibits a three-stage carbon isotope fractionation pattern:“Stable(Ⅰ)→Decrease(Ⅱ)→Increase(Ⅲ)”.A rapid decline in boundary pressure in stageⅢleads to fluctuations in isotope value,characterized by a“rapid decrease followed by continued increase”,with free gas being produced first and long-term supply of adsorbed gas.The CIF model can effectively match measured gas pressure,cumulative gas production,and δ^(13)C_(1) value of produced gas.During the first two stages of isotope fractionation,free gas dominated cumulative production.During the mid-late stages of slow depletion production,the staged pressure control development method can effectively increase the gas recovery.The production of adsorbed gas is primarily controlled by the rock's adsorption capacity and the presence of secondary flow channels.Effectively enhancing the recovery of adsorbed gas during the late stage remains crucial for maintaining stable production and improving the ultimate recovery factor of deep coal-rock gas.
基金Supported by the Joint Fund for Enterprise Innovation and Development of the National Natural Science Foundation of China(U23B20154)General Program of the National Natural Science Foundation of China(42372169)。
文摘To address the challenges in studying the pore formation and evolution processes,and unclear preservation mechanisms of deep to ultra-deep carbonate rocks,a high-temperature and high-pressure visualization simulation experimental device was developed for ultra-deep carbonate reservoirs.Carbonate rock samples from the Sichuan Basin and Tarim Basin were used to simulate the dissolution-precipitation process of deep to ultra-deep carbonate reservoirs in an analogous geological setting.This unit comprises four core modules:an ultra-high temperature,high pressure triaxial stress core holder module(temperature higher than 300°C,pressure higher than 150 MPa),a multi-stage continuous flow module with temperature-pressure regulation,an ultra-high temperature-pressure sapphire window cell and an in-situ high-temperature-pressure fluid property measurement module and real-time ultra-high temperature-pressure permeability detection module.The new experimental device was used for simulation experiment,the geological insights were obtained in three aspects.First,the pore-throat structure of carbonate is controlled by lithology and initial pore-throat structure,and fluid type,concentration and dissolution duration determine the degree of dissolution.The dissolution process exhibits two evolution patterns.The dissolution scale is positively correlated to the temperature and pressure,and the pore-forming peak period aligns well with the hydrocarbon generation peak period.Second,the dissolution potential of dolomite in an open flow system is greater than that of limestone,and secondary dissolved pores formed continuously are controlled by the type and concentration of acidic fluids and the initial physical properties.These pores predominantly distribute along pre-existing pore/fracture zones.Third,in a nearly closed diagenetic system,after the chemical reaction between acidic fluids and carbonate rock reaches saturation and dynamic equilibrium,the pore structure no longer changes,keeping pre-existing pores well-preserved.These findings have important guiding significance for the evaluation of pore-throat structure and development potential of deep to ultra-deep carbonate reservoirs,and the prediction of main controlling factors and distribution of high-quality carbonate reservoirs.
基金Supported by the National Undergraduate Innovation Training Program(Project No.202211437036).
文摘In this study,the hydraulic behavior and sand transport efficiency of the siphon automatic sand discharge device were studied by software simulation tests.By simulating the actual situation,this study analyzed how factors such as the difference in water level,sediment concentration,and pipeline layout affected the sediment discharge effect.The results show that the sediment discharge device can effectively discharge sediment under diverse operating conditions and show adaptability to different environmental conditions,which indicates that it is suitable for various types of reservoir environments.
基金funded by the Natural Science Foundation of China(Grants Nos.42272167,U24B6001,and 41772153)Science&Technology Project of Sinopec(Grant Nos.P23167 and P24173).
文摘Thiadiamondoids(TDs)have recently attracted increasing attention as molecular proxies for thermochemical sulfate reduction(TSR)reactions in reservoirs.However,their formation mechanisms,as well as the generation and evolution processes,remain poorly understood.In this study,simulation experiments with a duration of 160 h were conducted on the model compound 1,3-dimethyladamantane(1,3-DMA)using the CaSO_(4),MgSO_(4),and elemental S systems,with measurements at the 10th,20th,40th,80th and 160th hours during the simulation process being presented.The results indicate that at the end of simulation,the MgSO_(4) system exhibited the lowest residual amounts of 1,3-DMA,suggesting the highest degree of TSR.Four types of non-hydrocarbon compounds with adamantane structures were detected in the liquid products in the three experiment systems:adamantanones,adamantanols,adamantanethiols(ATs),and thiaadamantanes(TAs).Among these,adamantanones exhibited the highest concentrations in the three simulation systems.In addition,TAs were dominated by C_(3)-TAs in the CaSO_(4) and MgSO_(4) systems and by C_(2)-TAs in the elemental S system.The simulation experiments revealed a strong correlation between the concentrations of TAs and adamantanones,suggesting that adamantanones might be the intermediates for TAs.Combined with the synthesis mechanism of TAs from thiaadamamantane-4,8-dione,TDs might have two different genetic mechanisms:(a)low temperature cationic carbon ion rearrangement from diagenesis to early catagenesis stage,and(b)a free sulfur radical mechanism in high-temperature TSR process during middle-late catagenesis.TAs exhibited different generation and evolution processes across different experiment systems.Notably,the MgSO_(4) system revealed that TAs undergo generation,accumulation,and destruction process,corresponding to Easy%Ro values of 0.89%-0.98%,0.98%-1.21%,and>1.21%,respectively.Among these three simulation systems,dibenzothiophenes(DBTs)concentrations consistently trended upwards,indicating TAs have lower thermal stability than DBTs.
基金supported by the China Petroleum Science and Technology Major Project(No.2023ZZ18-03).
文摘The coal-bearing source rocks in the Jurassic Shuixigou Group have received widespread attention as the primary source rocks in the Turpan-Hami Basin of China,but the hydrocarbon generation potential and process of the mudstone in the Shuixigou Group,especially the mudstone at the top of the Sangonghe Formation,are unclear.Taking the source rocks of the Xishanyao Formation and the Sangonghe Formation as objectives,this study conducted rock pyrolysis and gold tube simulation experiment to investigate their hydrocarbon generation characteristics and differences.Our results indicate that the source rocks of the Xishanyao Formation include mudstone,carbonaceous mudstone and coal,and the quality of the source rocks is highly heterogeneous;the source rocks of the Sangonghe Formation are mainly composed of mudstone,and it is a good gas source rock.Simulation experiments found that the activation energy required for the generation of gaseous hydrocarbons by the mudstone of the Sangonghe Formation is lower than that by the mudstone of the Xishanyao Formation.The hydrocarbon generation process can be divided into three stages for both formations,but the gas generation potential of the Xishanyao Formation mudstone is higher than that of the Sangonghe Formation mudstone.A large amount of hydrocarbon was generated by the mudstone of the Xishanyao Formation when entering late thermal evolution,of which methane is dominant,mainly from the demethylation reaction of mature kerogen.On the other hand,a large amount of hydrocarbon was generated by the mudstone of the Sangonghe Formation in the early stage of thermal evolution,of which light hydrocarbon and wet gas are dominant,mainly from the early cracking stage of kerogen.This difference may be attributed to the structure of kerogen.The mudstone of the Xishanyao Formation is conducive to the formation of highly mature dry gas reservoirs,while the mudstone of the Sangonghe Formation is conducive to the formation of low maturity condensate gas and volatile oil reservoirs.The research result provides a scientific basis for the comparison of oil and gas sources and the evaluation of oil and gas resources in the Turpan-Hami Basin.
基金Supported by the National Natural Science Foundation of China(42362026)Key R&D Project of Xinjiang Uygur Autonomous Region(2024B01015).
文摘In the ultra-deep strata of the Tarim Basin,the vertical growth process of strike-slip faults remains unclear,and the vertical distribution of fractured-cavity carbonate reservoirs is complex.This paper investigates the vertical growth process of strike-slip faults through field outcrop observations in the Keping area,interpretation of seismic data from the Fuman Oilfield,Tarim Basim,NW China,and structural physical simulation experiments.The results are obtained mainly in four aspects.First,field outcrops and ultra-deep seismic profiles indicate a three-layer structure within the strike-slip fault,consisting of fault core,fracture zone and primary rock.The fault core can be classified into three parts vertically:fracture-cavity unit,fault clay and breccia zone.The distribution of fracture-cavity units demonstrates a distinct pattern of vertical stratification,owing to the structural characteristics and growth process of the slip-strike fault.Second,the ultra-deep seismic profiles show multiple fracture-cavity units in the strike-slip fault zone.These units can be classified into four types:top fractured,middle connected,deep terminated,and intra-layer fractured.Third,structural physical simulation experiments and ultra-deep seismic data interpretation reveal that the strike-slip faults have evolved vertically in three stages:segmental rupture,vertical growth,and connection and extension.The particle image velocimetry detection demonstrates that the initial fracture of the fault zone occurred at the top or bottom and then evolved into cavities gradually along with the fault growth,accompanied by the emergence of new fractures in the middle part of the strata,which subsequently connected with the deep and shallow cavities to form a complete fault zone.Fourth,the ultra-deep carbonate strata primarily develop three types of fractured-cavity reservoirs:flower-shaped fracture,large and deep fault and staggered overlap.The first two types are larger in size with better reservoir conditions,suggesting a significant exploration potential.
基金supported by the National Natural Science Foundation of China(No.50974029)the Doctoral Program of the Ministry of Education(No.20070220001)Province Natural Science Foundation of Heilongjiang of China(No.E200816)
文摘The mechanism of fracture initiation is the basic issue for hydraulic fracture technology. Because of the huge differences in fracture initiation mechanisms for different reservoirs,some successful fracturing techniques applied to porosity reservoirs are ineffectual for fractured reservoirs.Laboratory tests using a process simulation device were performed to confirm the characteristics of fracture initiation and propagation in different reservoirs.The influences of crustal stress field,confining pressure,and natural fractures on the fracture initiation and propagation are discussed.Experimental results demonstrate that stress concentration around the hole would significantly increase the fracture pressure of the rock.At the same time,natural fractures in the borehole wall would eliminate the stress concentration,which leads to a decrease in the fracture initiation pressure.
基金the National Science Foundation.USA.(NSF Grant EAR 02-10820)the National Natural ScienceFoundation of China(NSFC Grant No.40173031)+1 种基金the International Cooperative Research Foundation of NSFC(Grant No.2002-40210104086) the Ph.D.Base Foundation of the Ministry of Education of China(Grant No.20020284036).
文摘A simulated experimental reduction of and the synthesis of uraninite by a sulfate-reducing bacteria, Desulfovibrio desulfuricans DSM 642, are first reported. The simulated physicochemical experimental conditions were: 35°C, pH=7.0-7.4, corresponding to the environments of formation of the sandstone-hosted interlayer oxidation-zone type uranium deposits in Xinjiang, NW China. Uraninite was formed on the surface of the host bacteria after a one-week's incubation. Therefore, sulfate-reducing bacteria, which existed extensively in Jurassic sandstone-producing environments, might have participated in the biomineralization of this uranium deposit. There is an important difference in the order- disorder of the crystalline structure between the uraninite produced by Desulfovibrio desulfuricans and naturally occurring uraninite. Long time and slow precipitation and growth of uraninite in the geological environment might have resulted in larger uraninite crystals, with uraninite nanocrystals arranged in order, whereas the experimentally produced uraninite is composed of unordered uraninite nanocrystals which, in contrast, result from the short time span of formation and rapid precipitation and growth of uraninite. The discovery has important implications for understanding genetic significance in mineralogy, and also indicates that in-situ bioremediation of U-contaminated environments and use of biotechnology in the treatment of radioactive liquid waste is being contemplated.
基金Supported by the Major State Basic Research Development Program Fund （2010CB226801） the National Natural Science Foundation of China （50704034） the State Key Laboratory of Coal Resources and Safe Mining Open Research Fund （SKLCRSM11KFB08）
文摘Experiments simulating the effect of coal mine stopping through a fault zone were designed based on a working face of the Qianqiu coal mine in Yima, China. Through simulation of the physical process of fault reactivation and coal bumps, the displacement of the surrounding strata and evolution characteristics of fault stress under the effect of mining were studied. The mechanism of fault reactivation induced by coal mining was analyzed. The results show that shortly before fault reactiva- tion, the normal stress and shear stress increased rapidly and the risk of a fault slip occurring was also increased. The fault reac- tivation, caused by the mining activity, occurred when the working face was 25-35 m from the fault along the hanging wall. The influence of mining increased the possibility of fault reactivation, while the local failure of the bearing capacity of the working face was the direct cause of the fault slip. Our results indicate that the influence of fault slip on the coal of the working face had a transient impact and acted as a loading-unloading function.
基金the National Natural Science Foundation of China (40201009 and 90201007)Institute of Mountain Hazards and Environment, Chinese Academy of Sciences
文摘It＇s very important to simulate impact load of debris flow effectively and to investigate dynamic response of architectures under dynamic impact of debris flow, which are necessary to design disaster mitigation construction. Firstly, reinforced concrete domestic architectures in mountain areas of western China had been chosen as main architecture style. The bearing load style and the destructed shape of reinforced flamed construction impacted by discontinuous viscous debris flow were studied systematically. Secondly, Jiangjia Ravine debris flow valley in Yunnan Province, China had been chosen as research region. Utilizing based data from fieldwork and practical survey, the authors simulated and calculated theoretically impact force of discontinuous viscous debris flow. Thirdly, an impact data collecting system （IMHE IDCS） was designed and developed to fulfill designed simulation experiments. Finally, a series of impact test of researched structure models had been fulfilled. During experiment, the destructed shape and course of models were observed and the dynamic displacement data and main natural frequency data of models were collected and analyzed.
基金supported financially by the National Key R&D Program of China(No.2017YFC0307600)the Qingdao National Laboratory for Marine Science and Technology(No.QNLM2016ORP0207)+3 种基金the National Natural Science Foundation of China(No.41906067)the China Postdoctoral Science Foundation(No.2018M632634)the Natural Science Foundation of Shandong Province of China(No.ZR2019BD051)the Marine Geological Survey Program(Nos.DD20190221 and DD20190231)。
文摘Gas leakage is an important consideration in natural systems that experience gas hydrate accumulation.A number of velocity models have been created to study hydrate-bearing sediments,including the BGTL theory,the weighted equation,the Wood equation,the K-T equation,and the effective medium theory.In previous work,we regarded water as the pore fluid,which meant its density and bulk modulus values were those of water.This approach ignores the presence of gas,which results in a biased calculation of the pore fluid's bulk modulus and density.To take into account the effect of gas on the elastic wave velocity,it is necessary to recalculate the bulk modulus and density of an equivalent medium.Thus,a high-pressure reactor device for simulating leakage systems was developed to establish the relationship between wave velocity and hydrate saturation in methane-flux mode.A comparison of the values calculated by the velocity model with the experimental data obtained in this study indicates that the effective medium theory(EMT,which considers gas effects)is more applicable than other models.For hydrate saturations of 10%–30%,the result ranges between EMT-B(homogenous gas distribution)and EMT-B(patchy gas distribution).For hydrate saturations of 30%–60%,the results are similar to those of the EMT-B(homogenous gas distribution)mode,whereas hydrate saturations of 60%–70%yield results similar to those of the EMT-A mode.For hydrate saturations greater than 80%,the experimental results are similar to those of the EMT-B mode.These results have significance for hydrate exploitation in the South China Sea.
基金Project(50875268) supported by the National Natural Science Foundation of China Project(CSTC2008AB3057) supported by Foundation of Chongqing Science and Technology Commission, China+1 种基金 Project(108107) supported by the Key Project of Ministry of Education of China Project(50925518) supported by the National Science Fund for Distinguished Young Scholars
文摘In order to obtain satisfactory mechanical properties for the cam used in high-power ship diesel engines, a new quenching technology was proposed by designing a two-stage quenching process with an alkaline bath as the quenching medium. To demonstrate the effectiveness of the proposed new quenching technology, both numerical analysis and experimental study were performed. The new quenching technology was analyzed using finite element method. The combined effects of the temperature, stress and microstructure fields were investigated considering nonlinear material properties. Finally, an experimental study was performed to verify the effectiveness of the proposed new quenching technology. The numerical results show that internal stress is affected by both thermal stress and transformation stress. In addition, the direction of the internal stress is changed several times due to thermal interaction and microstructure evolution during the quenching process. The experimental results show that the proposed new quenching technology significantly improves the mechanical properties and microstructures of the cam. The tensile strength, the impact resistance and the hardness value of the cam by the proposed new quenching technology are improved by 4.3%, 8.9% and 3.5% compared with those by the traditional quenching technology. Moreover, the residual stress and cam shape deformation are reduced by 40.0% and 48.9% respectively for the cam manufactured by the new quenching technology.
基金Bombardier AerospaceThales+1 种基金the Consortium for Research and Innovation in Aerospace in Quebec(CRIAQ)the National Sciences and Engineering Research Council(NSERC)for the funding received in connection with the CRIAQ MDO 505 project。
文摘The paper deals with the design and experimental validation of the actuation mechanism control system for a morphing wing model.The experimental morphable wing model manufactured in this project is a full-size scale wing tip for a real aircraft equipped with an aileron.The morphing actuation of the model is based on a mechanism with four similar in house designed and manufactured actuators,positioned inside the wing on two parallel lines.Each of the four actuators used a BrushLess Direct Current(BLDC)electric motor integrated with a mechanical part performing the conversion of the angular displacements into linear displacements.The following have been chosen as successive steps in the design of the actuator control system:(A)Mathematical and software modelling of the actuator;(B)Design of the control system architecture and tuning using Internal Model Control(IMC)methodology;(C)Numerical simulation of the controlled actuator and its testing on bench and wind tunnel.The morphing wing experimental model is tested both at the laboratory level,with no airflow,to evaluate the components integration and the whole system functioning,but also in the wind tunnel,in the presence of airflow,to evaluate its behavior and the aerodynamic gain.
