A conventional solid-state process was used to synthesize the double perovskite materials HoRCoMnO_(6)(R=Ho,Gd,Eu,Nd).The structural properties of the compounds were investigated using X-ray powder diffraction(XRD).Th...A conventional solid-state process was used to synthesize the double perovskite materials HoRCoMnO_(6)(R=Ho,Gd,Eu,Nd).The structural properties of the compounds were investigated using X-ray powder diffraction(XRD).The results revealed that Ho_(2)CoMnO_(6) crystallizes in a monoclinic structure with the P2_(1)/n space group.In contrast,the other compounds HoRCoMnO_(6)(R=Gd,Eu,or Nd) exhibit an orthorhombic structure with the Pnma space group.As a result,the average crystallite size also changes as a function of rare-earth element doping.This investigation reveals that the magnetic properties of the compounds studied are significantly dependent on the doping elements.The Curie temperature T_C,for example,increases from 80 to 118℃ with the ionic radii of rare earths increasing.Furthermore,the study of the magnetocaloric effect(MCE) shows that the maximum of the entropy variation(-ΔS_(M)^(max)) increases from 4.97 to 6.06 J/(kg·K) under a magnetic field of 5 T with substitution by rare-earth ions.To examine the efficiency of MCE materials,the relative cooling power(RCP) was evaluated and is found to increase with increment of rare-earth radius till 406.69 J/kg for Nd.The mean entropy variation with tempe rature(TEC) was also studied.Due to their significant magnetocaloric performance,HoRCoMnO_(6)(noted as HRCMO) compounds(with R=Ho,Gd,Eu or Nd) could be good candidates for low-temperature magnetic cooling applications.展开更多
The spatial relationship between structural planes and principal stresses significantly affects the mechanical properties of deep hard rock.This paper examines the effect of the loading angle under true triaxial compr...The spatial relationship between structural planes and principal stresses significantly affects the mechanical properties of deep hard rock.This paper examines the effect of the loading angle under true triaxial compression.While previous studies focused on the angleβbetween the maximum principal stress and the structural plane,the role of angleω,between the intermediate principal stress and the structural plane,is often overlooked.Utilizing artificially prefabricated granite specimens with a single non-penetrating structural plane,we set the loading angleβto range from 0°to 90°across seven groups,and assignedωvalues of 0°and 90°in two separate groups.The results show that the peak strength is negatively correlated withβup to 45°,beyond which it tends to stabilize.The angleωexerts a strengthening effect on the peak strength.Deformation mainly occurs post-peak,with the strain values ε_(1) and ε_(3) reaching levels 2−3 times higher than those in intact rock.The structural plane significantly influences failure mode whenω=0°,while failure localizes near the σ_(3) surface of the specimens whenω=90°.The findings enhance data on structural plane rocks under triaxial compression and inform theoretical research,excavation,and support design of rock structures.展开更多
Taking the Wangfu fault depression in the Songliao Basin as an example,on the basis of seismic interpretation and drilling data analysis,the distribution of the basement faults was clarified,the fault activity periods...Taking the Wangfu fault depression in the Songliao Basin as an example,on the basis of seismic interpretation and drilling data analysis,the distribution of the basement faults was clarified,the fault activity periods of the coal-bearing formations were determined,and the fault systems were divided.Combined with the coal seam thickness and actual gas indication in logging,the controls of fault systems in the rift basin on the spatial distribution of coal and the occurrence of coal-rock gas were identified.The results show that the Wangfu fault depression is an asymmetrical graben formed under the control of basement reactivated strike-slip T-rupture,and contains coal-bearing formations and five sub-types of fault systems under three types.The horizontal extension strength,vertical activity strength and tectono-sedimentary filling difference of basement faults control vertical stratigraphic sequences,accumulation intensity,and accumulation frequency of coal seam in rift basin.The structural transfer zone formed during the segmented reactivation and growth of the basement faults controls the injection location of steep slope exogenous clasts.The filling effect induced by igneous intrusion accelerates the sediment filling process in the rift lacustrine area.The structural transfer zone and igneous intrusion together determine the preferential accumulation location of coal seams in the plane.The faults reactivated at the basement and newly formed during the rifting phase serve as pathways connecting to the gas source,affecting the enrichment degree of coal-rock gas.The vertical sealing of the faults was evaluated by using shale smear factor(SSF),and the evaluation criterion was established.It is indicated that the SSF is below 1.1 in major coal areas,indicating favorable preservation conditions for coal-rock gas.Based on the influence factors such as fault activity,segmentation and sealing,the coal-rock gas accumulation model of rift basin was established.展开更多
Due to the uneven distribution of pore size in coal and its wide distribution range,it is difficult to effectively characterize the multi-scale pore structure of coal by a single method.In this paper,the multi-scale p...Due to the uneven distribution of pore size in coal and its wide distribution range,it is difficult to effectively characterize the multi-scale pore structure of coal by a single method.In this paper,the multi-scale pore structure characteristics of coal were analyzed comprehensively by using scanning electron microscope,low-temperature liquid nitrogen adsorption,high-pressure mercury intrusion and constant-rate mercury intrusion.In addition,the effects of metamorphism on the volume and specific surface area of pores in coal were revealed,and the relationships between coal rock permeability and pore structure characteristic parameters were described.And the following research results were obtained.First,with the increase of coal metamorphism,the volume and specific surface area of nanopores in coal decrease first and then increase,and they reach the minimum value when Ro,max is about 1.8%.Second,the pore and throat radii of coal samples are overall in the form of normal distribution.And with the increase of coal metamorphism,the pore radius corresponding to the maximum distribution frequency increases.Third,the samples of low-rank bituminous coal are the highest in throat radius distribution range,connected throat radius and average throat radius.Fourth,the samples of anthracite coal are the lowest in throat radius distribution range and connected throat radius.Fifth,there is a single main peak in the distribution of pore-throat ratios of low-and medium-rank bituminous coal samples,and the pore-throat ratios corresponding to the main peak is relatively low.Sixth,the permeability of coal is in a positive correlation with porosity and an average throat radius,and in a negative correlation with an average pore-throat ratio,but in no obvious correlation with an average pore radius.展开更多
In this paper, a typical mei-yu front process with heavy rainfall from June 12 to 15 in 1998 is analyzed. The results show that the mei-yu front is a front system which consists of an iso-theta(e) dense area with stro...In this paper, a typical mei-yu front process with heavy rainfall from June 12 to 15 in 1998 is analyzed. The results show that the mei-yu front is a front system which consists of an iso-theta(e) dense area with strong horizontal gradient, a deep-convective cloud tower band, a passageway transporting warm and moist air flow from the summer monsoon surge in the mid and low levels to the south of the mei-yu front, and a migrating synoptic scale trough to the north of the mei-yu front, which transports cold and dry air southward in the mid and upper levels. The maintenance of the mei-yu front is realized by: (1) is a positive feedback between the moist physical process enhancing frontogenesis and the development of the strong convective system in front of the mei-yu front; (2) the sustaining system to the north of the mei-yu front which is a migrating synoptic scale trough transporting cold and dry air to the mei-yu front and positive vorticity to the mesoscale system in front of the mei-yu front.展开更多
Well-developed pores and cracks in coal reservoirs are the main venues for gas storage and migration.To investigate the multi-scale pore fractal characteristics,six coal samples of different rankings were studied usin...Well-developed pores and cracks in coal reservoirs are the main venues for gas storage and migration.To investigate the multi-scale pore fractal characteristics,six coal samples of different rankings were studied using high-pressure mercury injection(HPMI),low-pressure nitrogen adsorption(LPGA-N2),and scanning electron microscopy(SEM)test methods.Based on the Frankel,Halsey and Hill(FHH)fractal theory,the Menger sponge model,Pores and Cracks Analysis System(PCAS),pore volume complexity(D_(v)),coal surface irregularity(Ds)and pore distribution heterogeneity(D_(p))were studied and evaluated,respectively.The effect of three fractal dimensions on the gas adsorption ability was also analyzed with high-pressure isothermal gas adsorption experiments.Results show that pore structures within these coal samples have obvious fractal characteristics.A noticeable segmentation effect appears in the Dv1and Dv2fitting process,with the boundary size ranging from 36.00 to 182.95 nm,which helps differentiate diffusion pores and seepage fractures.The D values show an asymmetric U-shaped trend as the coal metamorphism increases,demonstrating that coalification greatly affects the pore fractal dimensions.The three fractal dimensions can characterize the difference in coal microstructure and reflect their influence on gas adsorption ability.Langmuir volume(V_(L))has an evident and positive correlation with Dsvalues,whereas Langmuir pressure(P_(L))is mainly affected by the combined action of Dvand Dp.This study will provide valuable knowledge for the appraisal of coal seam gas reservoirs of differently ranked coals.展开更多
Advanced chemical engineering for simultaneous modulation of nanomaterial morphology, defects, interfaces, and structure to enhance electromagnetic and microwave absorption (MA) performance. However, accurately distin...Advanced chemical engineering for simultaneous modulation of nanomaterial morphology, defects, interfaces, and structure to enhance electromagnetic and microwave absorption (MA) performance. However, accurately distinguishing the MA contributions of different scale factors and tuning the optimal combined effects remains a formidable challenge. This study employs a synergistic approach combining template protection etching and vacuum annealing to construct a controlled system of micrometer-sized cavities and amorphous carbon matrices in metal-organic framework (MOF) derivatives. The results demonstrate that the spatial effects introduced by the hollow structure enhance dielectric loss but significantly weaken impedance matching. By increasing the proportion of amorphous carbon, the balance between electromagnetic loss and impedance matching can be effectively maintained. Importantly, in a suitable graphitization environment, the presence of oxygen vacancies in amorphous carbon can induce significant polarization to compensate for the reduced conductivity loss due to the absence of sp2 carbon. Through the synergistic effects of morphology and composition, the samples exhibit a broader absorption bandwidth (6.28 GHz) and stronger reflection loss (−61.64 dB) compared to the original MOF. In conclusion, this study aims to elucidate the multiscale impacts of macroscopic micro-nano structure and microscopic defect engineering, providing valuable insights for future research in this field.展开更多
Improving the volumetric energy density of supercapacitors is essential for practical applications,which highly relies on the dense storage of ions in carbon-based electrodes.The functional units of carbon-based elect...Improving the volumetric energy density of supercapacitors is essential for practical applications,which highly relies on the dense storage of ions in carbon-based electrodes.The functional units of carbon-based electrode exhibit multi-scale structural characteristics including macroscopic electrode morphologies,mesoscopic microcrystals and pores,and microscopic defects and dopants in the carbon basal plane.Therefore,the ordered combination of multi-scale structures of carbon electrode is crucial for achieving dense energy storage and high volumetric performance by leveraging the functions of various scale structu re.Considering that previous reviews have focused more on the discussion of specific scale structu re of carbon electrodes,this review takes a multi-scale perspective in which recent progresses regarding the structureperformance relationship,underlying mechanism and directional design of carbon-based multi-scale structures including carbon morphology,pore structure,carbon basal plane micro-environment and electrode technology on dense energy storage and volumetric property of supercapacitors are systematically discussed.We analyzed in detail the effects of the morphology,pore,and micro-environment of carbon electrode materials on ion dense storage,summarized the specific effects of different scale structures on volumetric property and recent research progress,and proposed the mutual influence and trade-off relationship between various scale structures.In addition,the challenges and outlooks for improving the dense storage and volumetric performance of carbon-based supercapacitors are analyzed,which can provide feasible technical reference and guidance for the design and manufacture of dense carbon-based electrode materials.展开更多
As the second most important solid waste produced by coal-fired power plants,the improper management of coal-fired slag has the potential to result in environmental pollution.It is therefore imperative that high-value...As the second most important solid waste produced by coal-fired power plants,the improper management of coal-fired slag has the potential to result in environmental pollution.It is therefore imperative that high-value utilization pathways for coal-fired slag should be developed.In this study,modified magnesium slag(MMS),produced by a magnesium smelter,was selected as the alkali activator.The activated silica-aluminum solid wastes,namely coal-fired slag(CFS)and mineral powder(MP),were employed as pozzolanic materials in the preparation of alkali-activated cementitious materials.The alkali-activated cementitious materials prepared with 50 wt%MMS,40 wt%CFS and 10 wt%MP exhibited favorable mechanical properties,with a compressive strength of 32.804 MPa in the paste sample cured for 28 d.Then,the activated silica-aluminum solid waste consisting of CFS-MP generated a significant amount of C-S(A)-H gels,AFt,and other products,which were observed to occupy the pore structure of the specimen.In addition,the secondary hydration reaction of CFS-MP occurs in high alkalinity environments,resulting in the formation of a mutually stimulated and promoted reaction system between CFS-MP and MMS,this will subsequently accelerate the hydrolysis reaction of MMS.It is important to emphasize that the amount of MMS in alkali-activated cementitious materials must be strictly regulated to avert the potential issue of incomplete depolymerization-repolymerization of active silica-aluminum solid waste containing CFS-MP.This in turn could have a deleterious impact on the late strength of the cementitious materials.The aim of this work is to improve the joint disposal of MMS,CFS and MP and thereby provide a scientific basis for the development of environmentally friendly and low-carbon modified magnesium slag alkali-activated coal-fired slag based cementitious materials for mine backfilling.展开更多
This study systematically investigated the effects of different gas stove structures on flame combustion characteristics using spectral diagnostic techniques,aiming to provide optimized design guidelines for clean ene...This study systematically investigated the effects of different gas stove structures on flame combustion characteristics using spectral diagnostic techniques,aiming to provide optimized design guidelines for clean energy applications.To explore the combustion behaviors of various gas stove structures,UV cameras,high-speed cameras,and K-type thermocouples were employed to measure parameters such as flame OH radicals(OH*),flame morphology,pulsation frequency,flame temperature,and heat flux.The results demonstrate that flame stability was achieved at an inner/outer cover flow rate ratio of 0.5/4.0 L/min,beyond which further flow rate increases led to reduced combustion efficiency.Compared to covered stoves,top-uncovered stove exhibited 5.5%and 12.4%higher temperatures at the inner and outer covers,respectively,along with a 35%increase in heat flux.Comprehensive analysis revealed an approximately 20%enhancement in overall flame intensity.The experimental results show that top-uncovered gas stoves exhibit higher flame intensity,greater combustion efficiency,and overall higher stove efficiency.In contrast,covered gas stoves feature a more controllable and stable flame with a gentler temperature rise.This study underscores the importance of optimizing gas stove designs to enhance combustion efficiency and reduce emissions,contributing to the transition from fossil fuels to renewable energy sources and promoting sustainable development.展开更多
Double-shaft-driven needle punching machine is a specialized equipment designed for processing C/C crucible preforms.Its main needle punching module is operated by two sets of reciprocating crank-slider mechanisms.The...Double-shaft-driven needle punching machine is a specialized equipment designed for processing C/C crucible preforms.Its main needle punching module is operated by two sets of reciprocating crank-slider mechanisms.The intense vibration during needle punching not only generates huge noise,but also substantially reduces the quality of the preform.It is imperative to perform a dynamic analysis and optimization of the entire needle punching machine.In this paper,the three-dimensional(3D)model of the entire double-shaft-driven needle punching machine for C/C crucible preforms is established.Based on the modal analysis theory,the modal characteristics of the needle punching machine under various operating conditions are analyzed and its natural frequencies and vibration modes are determined.The harmonic response analysis is then employed to obtain the amplitude of the needle plate at different frequencies,and the structural weak points of the needle punching machine are identified and improved.The feasibility of the optimized scheme is subsequently reevaluated and verified.The results indicate that the first six natural frequencies of the machine increase,and the maximum amplitude of the needle plate decreases by 70.3%.The enhanced dynamic characteristics of the machine significantly improve its performance,enabling more efficient needle punching of C/C crucible preforms.展开更多
This study investigates the Benxi Formation sandstone reservoirs in the Yanchuan East Block of the Ordos Basin,employing an integrated approach that includes core observation,thin-section analysis,scanning electron mi...This study investigates the Benxi Formation sandstone reservoirs in the Yanchuan East Block of the Ordos Basin,employing an integrated approach that includes core observation,thin-section analysis,scanning electron microscopy,high-pressure mercury intrusion,and petrophysical testing to systematically evaluate reservoir petrographic features and pore structures.Results reveal that Benxi Formation sandstones predominantly comprise quartz sandstones,lithic quartz sandstones,and lithic sandstones,characterized by high quartz content,widespread volcanic lithic fragments,moderately well-sorted grains,and complex cement types.Pore types are dominated by residual intergranular and dissolution pores,with minor intracrystalline pores and fractures;overall porosity ranges from 0.17%to 9.07%(average 4.74%),and permeability from 0.01 to 6.05 mD,classifying them as ultra-low porosity and tight reservoirs.High-pressure mercury intrusion indicates microfine throats as the primary structure,divisible into four distinct types.Diagenetically,compaction and cementation are the main drivers of primary pore loss and reservoir tightening,whereas late-stage dissolution partially ameliorates pore networks.Overall,Benxi Formation sandstone reservoirs exhibit pervasive densification but localized favorable pore assemblages and connectivity,facilitating hydrocarbon migration and accumulation.These findings advance understanding of Upper Paleozoic tight sandstone reservoir characteristics and aid in predicting sweet spots.展开更多
Upon approaching 850℃,the GH4151 alloy exhibits diminished high-temperature strength,primarily attributed to the disruption of γ′phase coherence at elevated temperatures,which reduces its strengthening contribution...Upon approaching 850℃,the GH4151 alloy exhibits diminished high-temperature strength,primarily attributed to the disruption of γ′phase coherence at elevated temperatures,which reduces its strengthening contribution.Tantalum(Ta)additions enhance the stability of the γ′phase but introduce processing challenges,including pronounced solidification segregation,the formation of secondary phases,and increased susceptibility to cracking during processing.The influence of Ta content on elemental segregation,solidification microstructure,phase precipitation kinetics,and hot deformation behaviour in GH4151 was systematically investigated.Processing windows derived from the dynamic materials model(DMM)and microstructural evolution under varying thermomechanical conditions are further examined.Key findings reveal the severe Ta segregation(segregation coefficient K≈1.608);Ta promotes γ/γ′eutectic and η phase formation,increasing γ′phase volume fraction from 54% to approximately 63%;and increased Ta content elevates flow stress and progressively narrows the DMM-defined processing window;optimized thermomechanical processing parameters(elevated temperatures and strain rates)enhance recrystallization kinetics and hot workability,thereby mitigating cracking propensity.展开更多
To improve the adaptability of TBMs in diverse geological environments,this paper proposes a reconfigurable Type-V thrust mechanism(V-TM)with rearrangeable working states,in which structural stiffness can be automatic...To improve the adaptability of TBMs in diverse geological environments,this paper proposes a reconfigurable Type-V thrust mechanism(V-TM)with rearrangeable working states,in which structural stiffness can be automatically altered during operation.Therefore,millions of configurations can be obtained,and thousands of instances of working status per configuration can be set respectively.Nonetheless,the complexity of configurations and diversity of working states contributes to further complications for the structural stiffness algorithm.This results in challenges such as difficulty calculating the payload compliance index and the environment adaptability index.To solve this problem,we use the configuration matrix to describe the relationship between propelling jacks under reconfiguration and adopt pattern vectors to describe the working state of each hydraulic cylinder.Then,both the dynamic compatible equation between propeller forces of the hydraulic cylinders and driving forces,and the kinematic harmonizing equation between the hydraulic cylinder displacements and their deformations are established.Next,we derive the stiffness analytical equation using Hooke’s law and the Jacobian Matrix.The proposed approach provides an effective algorithm to support structural rigidity analysis,and lays a solid theoretical foundation for calculating the performance indexes of the V-TM.We then analyze the rigidity characteristics of typical configurations under different working states,and obtain the main factors affecting structural stiffness of the V-TM.The results show the deviation degree of structural parameters in hydraulic cylinders within the same group,and the working status of propelling jacks.Finally,our constructive conclusions contribute valuable information for matching and optimization by drawing on the factors that affect the structural rigidity of the V-TM.展开更多
The effect of application of pig manure (PM) on the structural characteristics of humic acids (HAs) of brown soil was studied in field and incubation experiments. The results showed that the number-average molecular w...The effect of application of pig manure (PM) on the structural characteristics of humic acids (HAs) of brown soil was studied in field and incubation experiments. The results showed that the number-average molecular weights (Mn), the ratios of C/ H, C/ N and O/C, the contents of carboxyl and phenolic hydroxyl groups, the content ofaromatic C, the values of E2, E4and λ Exmax of HAs all decreased; whereas, the contents of alkyl C and O-alkyl C, the ratio of carboxyl to phenolic hydroxyl groups, the degree of oxidation stability, the absorption intensity at 285 mμ (UV), and 2920cm-1 of HAs increased after the application of PM. The above results indicated that the molecular structure of HAs tended to be more aliphatic and simpler after the application of PM.展开更多
In the design process of advanced aero-engines,it is necessary to carry out an effective analysis method between structural features and mechanical characteristics for a better structural optimization.Based on the str...In the design process of advanced aero-engines,it is necessary to carry out an effective analysis method between structural features and mechanical characteristics for a better structural optimization.Based on the structural composition and functions of aero-engines,the concept and contents of structural efficiency can reflect the relation between structural features and mechanical characteristics.In order to achieve the integrated design of structural and mechanical characteristics,one quantitative analysis method called Structural Efficiency Assessment Method(SEAM)was put forward.The structural efficiency coefficient was obtained by synthesizing the parameters to quantitatively evaluate the aero-engine structure design level.Parameterization method to evaluate structural design quality was realized.After analyzing the structural features of an actual dual-rotor system in typical high bypass ratio turbofan engines,the mechanical characteristics and structural efficiency coefficient were calculated.Structural efficiency coefficient of high-pressure rotor(0.43)is higher than that of low-pressure rotor(0.29),which directly shows the performance of the former is better,there is room for improvement in structural design of the low-pressure rotor.Thus the direction of structural optimization was pointed out.The applications of SEAM shows that the method is operational and effective in the evaluation and improvement of structural design.展开更多
Based on 2D and 3D seismic data,the latest drilling data and field outcrop data of the northern slope of the Central Sichuan paleo-uplift,the structural analysis method is used to analyze unconformity development char...Based on 2D and 3D seismic data,the latest drilling data and field outcrop data of the northern slope of the Central Sichuan paleo-uplift,the structural analysis method is used to analyze unconformity development characteristics and fault characteristics during the key structural transformation period,discussing the influence of the structural characteristics on the hydrocarbon accumulation of deep carbonate rocks.The results show that:(1)The two key unconformities of the Tongwan and Caledonian periods were primarily developed in deep carbonate rocks.Firstly,Tongwan’s unconformities are characterized by regional disconformities between the second and third members of the Dengying Formation,the top formation of the Sinian and the lower Cambrian,strips of which zigzag through the north and south sides of the study area.Secondly,the Caledonian unconformity is characterized by a regional unconformable contact between the lower Permian and the ower Paleozoic strata.From NE to SW,the age of the strata,which were subject to erosion,changes from new to old,the denudation distribution showing as a nose-shaped structure which inclines towards the ENE.(2)Boundary fault and transtensional strike-slip faults developed in the Sinian to Paleozoic strata.In profile,there are three types of structural styles:steep and erect,flower structures,’Y’and reversed’Y’type faults.In plane view,the Sinian developed extensional boundary faults extending in an almost NS direction,strike-slip faults developing and extending linearly in approximately EW,WNW and NE strikes in the Cambrian,with characteristically more in the south and less in the north.(3)The faults in the northern slope show obvious zonal deformations in transverse view as well as significant stages and stratified activity in a longitudinal direction.Among them,the activity of faults in the Sinian was the strongest,followed by the activity in the Cambrian period,the activity intensity of faults in the Permian period being the weakest.This fault activity can be divided into four periods:Sinian,Cambrian-Permian,the early Indosinian period and the late Indosinian-Himalayan period,the transtensional strikeslip faults being the products of oblique extensions of pre-existing weak zones in the Xingkai and Emei taphrogenesis,with a particular inheritance in the main faults.(4)Combined with hydrocarbon accumulation factors,it is considered that the epigenetic karstification of the Tongwan and Caledonian unconformities in the northern slope controlled the formation and distribution of carbonate karst reservoirs over a large area,also acting as a good pathway for oil and gas migration.The extensional faults developed at the margin of the NS trending rift,controlling the sag-platform sedimentary pattern in the Dengying Formation of the Sinian.Strike-slip faults in NE,WNW and ENE directions may control the microgeomorphological pattern inside the platform and intensify the differential distribution of grain beach facies.The multi-stage hereditary activity of strike-slip faults not only improved the porosity and permeability of the reservoirs,but also acted as the main channel of oil and gas migration,providing favorable conditions for the development of the current multi-layer gasbearing scenario in the northern slope of the Central Sichuan Basin.展开更多
There are two mechanisms of the coarse surface asperity resistance effect and rubbing resistance effect in the course of the soft rock structural surface creep,of which the former plays a dominant role in hindering th...There are two mechanisms of the coarse surface asperity resistance effect and rubbing resistance effect in the course of the soft rock structural surface creep,of which the former plays a dominant role in hindering the deformation in the starting creep phase,so that the structural surface creep usually displays the strong surface roughness effect,and so does the latter when the asperities in the coarse surface were fractured by shearing.Under the low stress condition,there are only two phases of the decelerating creep and the constant creep for the soft rock structural surface,and as the stress increases and overcomes the rubbing resistance,the accelerating creep failure of the structural surface will happen suddenly.Therefore,a multiple rheological model,which combines the nonlinear NEWTON body(NN) of a certain mass and the empirical plastic body(EM) with the classical SAINT VENANT body,NEWTON body,KELVIN body and HOOKE body,could be used to comprehensively describe the creep characteristics of the soft rock structural surface.Its mechanical parameter values will vary owing to the different surface roughness of the structural surface.The parameters of GH,GK and ηL are positively linearly correlative to the surface roughness.The surface roughness and m are negative exponential function correlation.The long-term strength τS is positively correlative to the surface roughness.展开更多
Two-dimensional disordered granular assemblies composed of 2048 polydispersed frictionless disks are simulated using the discrete element method. The height of the first peak of the pair correlation function, gl, the ...Two-dimensional disordered granular assemblies composed of 2048 polydispersed frictionless disks are simulated using the discrete element method. The height of the first peak of the pair correlation function, gl, the local and global bond orientational parameters ψ6^1 and ψ6^g, and the fluctuations of these parameters decrease with increasing polydispersity s, implying the transition from a polycrystalline state to an amorphous state in the system. As s increases, the peak position of the boson peak aJBp shifts towards a lower frequency and the intensity of the boson peak D（ωBP）/ωBp increases, indicating that the position and the strength of the boson peak are controlled by the polydispersity of the system. Moreover, the inverse of the boson peak intensity ωBP/D（ωBP）, the shear modulus G, and the basin curvature SIS all have a similar dependence on s, implying that the s dependence of the vibrational density of states at low frequencies likely originates from the s dependence of the basin curvature.展开更多
When an output curve force is applied to a horizontal servo cylinder with a heavy load, the piston rod bears a dynamic partial load based on the installation and load characteristics, which significantly a ects the fr...When an output curve force is applied to a horizontal servo cylinder with a heavy load, the piston rod bears a dynamic partial load based on the installation and load characteristics, which significantly a ects the frequency response and control accuracy of the servo cylinder. Based on this partial load, increased friction can lead to cylinder bore scu ng, leakage, lack of output power, or even system failure. In this paper, a novel asymmetric static-pressure support structure is proposed based on the principle of hydrostatic support. The radial component force of a dynamic partial load is balanced by cooperation between the support oil cushion of the variable hydraulic pressure support structure, oil cushion of the supportive force, and the damper. Adaptive control of the servo cylinder piston rod, guide sleeve, and piston, as well as the cylinder oil film friction between lubricated surfaces is achieved. In this paper, theoretical design and analysis of the traditional hydrostatic bearing structure and novel structure are presented. A hydraulic dynamic shear scissor is used as a research target to derive a structural dynamic model. Comparative simulations are performed using Matlab Simulink. Additionally, flow field analysis of the novel structure is performed, which verifies the rationality and feasibility of the proposed structure and system.展开更多
文摘A conventional solid-state process was used to synthesize the double perovskite materials HoRCoMnO_(6)(R=Ho,Gd,Eu,Nd).The structural properties of the compounds were investigated using X-ray powder diffraction(XRD).The results revealed that Ho_(2)CoMnO_(6) crystallizes in a monoclinic structure with the P2_(1)/n space group.In contrast,the other compounds HoRCoMnO_(6)(R=Gd,Eu,or Nd) exhibit an orthorhombic structure with the Pnma space group.As a result,the average crystallite size also changes as a function of rare-earth element doping.This investigation reveals that the magnetic properties of the compounds studied are significantly dependent on the doping elements.The Curie temperature T_C,for example,increases from 80 to 118℃ with the ionic radii of rare earths increasing.Furthermore,the study of the magnetocaloric effect(MCE) shows that the maximum of the entropy variation(-ΔS_(M)^(max)) increases from 4.97 to 6.06 J/(kg·K) under a magnetic field of 5 T with substitution by rare-earth ions.To examine the efficiency of MCE materials,the relative cooling power(RCP) was evaluated and is found to increase with increment of rare-earth radius till 406.69 J/kg for Nd.The mean entropy variation with tempe rature(TEC) was also studied.Due to their significant magnetocaloric performance,HoRCoMnO_(6)(noted as HRCMO) compounds(with R=Ho,Gd,Eu or Nd) could be good candidates for low-temperature magnetic cooling applications.
基金Projects(51979268,52279117,52309146)supported by the National Natural Science Foundation of ChinaProject(SKLGME-JBGS2401)supported by the Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,China。
文摘The spatial relationship between structural planes and principal stresses significantly affects the mechanical properties of deep hard rock.This paper examines the effect of the loading angle under true triaxial compression.While previous studies focused on the angleβbetween the maximum principal stress and the structural plane,the role of angleω,between the intermediate principal stress and the structural plane,is often overlooked.Utilizing artificially prefabricated granite specimens with a single non-penetrating structural plane,we set the loading angleβto range from 0°to 90°across seven groups,and assignedωvalues of 0°and 90°in two separate groups.The results show that the peak strength is negatively correlated withβup to 45°,beyond which it tends to stabilize.The angleωexerts a strengthening effect on the peak strength.Deformation mainly occurs post-peak,with the strain values ε_(1) and ε_(3) reaching levels 2−3 times higher than those in intact rock.The structural plane significantly influences failure mode whenω=0°,while failure localizes near the σ_(3) surface of the specimens whenω=90°.The findings enhance data on structural plane rocks under triaxial compression and inform theoretical research,excavation,and support design of rock structures.
基金Supported by the National Natural Science Foundation of China(42472190)Chongqing Natural Science Foundation Innovation and Development Joint Fund Project(CSTB2022NSCQ-LZX0020)Chongqing Talent Innovation and Entrepreneurship Leading Talent Project(0255-19230101042)。
文摘Taking the Wangfu fault depression in the Songliao Basin as an example,on the basis of seismic interpretation and drilling data analysis,the distribution of the basement faults was clarified,the fault activity periods of the coal-bearing formations were determined,and the fault systems were divided.Combined with the coal seam thickness and actual gas indication in logging,the controls of fault systems in the rift basin on the spatial distribution of coal and the occurrence of coal-rock gas were identified.The results show that the Wangfu fault depression is an asymmetrical graben formed under the control of basement reactivated strike-slip T-rupture,and contains coal-bearing formations and five sub-types of fault systems under three types.The horizontal extension strength,vertical activity strength and tectono-sedimentary filling difference of basement faults control vertical stratigraphic sequences,accumulation intensity,and accumulation frequency of coal seam in rift basin.The structural transfer zone formed during the segmented reactivation and growth of the basement faults controls the injection location of steep slope exogenous clasts.The filling effect induced by igneous intrusion accelerates the sediment filling process in the rift lacustrine area.The structural transfer zone and igneous intrusion together determine the preferential accumulation location of coal seams in the plane.The faults reactivated at the basement and newly formed during the rifting phase serve as pathways connecting to the gas source,affecting the enrichment degree of coal-rock gas.The vertical sealing of the faults was evaluated by using shale smear factor(SSF),and the evaluation criterion was established.It is indicated that the SSF is below 1.1 in major coal areas,indicating favorable preservation conditions for coal-rock gas.Based on the influence factors such as fault activity,segmentation and sealing,the coal-rock gas accumulation model of rift basin was established.
基金sponsored by the National Natural Science Foundation of China“Structural evolution characteristics of microfissures in structural coal and its control on permeability of coal reservoir”(No.41772162)the Program for Innovative Research Team(in Science and Technology)in University of Henan Province“Physical properties of coalbed methane reservoir and its geological control”(No.17IRTSTHN025).
文摘Due to the uneven distribution of pore size in coal and its wide distribution range,it is difficult to effectively characterize the multi-scale pore structure of coal by a single method.In this paper,the multi-scale pore structure characteristics of coal were analyzed comprehensively by using scanning electron microscope,low-temperature liquid nitrogen adsorption,high-pressure mercury intrusion and constant-rate mercury intrusion.In addition,the effects of metamorphism on the volume and specific surface area of pores in coal were revealed,and the relationships between coal rock permeability and pore structure characteristic parameters were described.And the following research results were obtained.First,with the increase of coal metamorphism,the volume and specific surface area of nanopores in coal decrease first and then increase,and they reach the minimum value when Ro,max is about 1.8%.Second,the pore and throat radii of coal samples are overall in the form of normal distribution.And with the increase of coal metamorphism,the pore radius corresponding to the maximum distribution frequency increases.Third,the samples of low-rank bituminous coal are the highest in throat radius distribution range,connected throat radius and average throat radius.Fourth,the samples of anthracite coal are the lowest in throat radius distribution range and connected throat radius.Fifth,there is a single main peak in the distribution of pore-throat ratios of low-and medium-rank bituminous coal samples,and the pore-throat ratios corresponding to the main peak is relatively low.Sixth,the permeability of coal is in a positive correlation with porosity and an average throat radius,and in a negative correlation with an average pore-throat ratio,but in no obvious correlation with an average pore radius.
文摘In this paper, a typical mei-yu front process with heavy rainfall from June 12 to 15 in 1998 is analyzed. The results show that the mei-yu front is a front system which consists of an iso-theta(e) dense area with strong horizontal gradient, a deep-convective cloud tower band, a passageway transporting warm and moist air flow from the summer monsoon surge in the mid and low levels to the south of the mei-yu front, and a migrating synoptic scale trough to the north of the mei-yu front, which transports cold and dry air southward in the mid and upper levels. The maintenance of the mei-yu front is realized by: (1) is a positive feedback between the moist physical process enhancing frontogenesis and the development of the strong convective system in front of the mei-yu front; (2) the sustaining system to the north of the mei-yu front which is a migrating synoptic scale trough transporting cold and dry air to the mei-yu front and positive vorticity to the mesoscale system in front of the mei-yu front.
基金The first author would like to express sincere appreciation for the scholarship provided by China Scholarship Council(No.202006430006)and University of Wollongongfinancially supported by the ACARP Project C28006+1 种基金the National Key Research and Development Program of China(No.2018YFC0808301)the Natural Science Foundation of Beijing Municipality,China(No.8192036)。
文摘Well-developed pores and cracks in coal reservoirs are the main venues for gas storage and migration.To investigate the multi-scale pore fractal characteristics,six coal samples of different rankings were studied using high-pressure mercury injection(HPMI),low-pressure nitrogen adsorption(LPGA-N2),and scanning electron microscopy(SEM)test methods.Based on the Frankel,Halsey and Hill(FHH)fractal theory,the Menger sponge model,Pores and Cracks Analysis System(PCAS),pore volume complexity(D_(v)),coal surface irregularity(Ds)and pore distribution heterogeneity(D_(p))were studied and evaluated,respectively.The effect of three fractal dimensions on the gas adsorption ability was also analyzed with high-pressure isothermal gas adsorption experiments.Results show that pore structures within these coal samples have obvious fractal characteristics.A noticeable segmentation effect appears in the Dv1and Dv2fitting process,with the boundary size ranging from 36.00 to 182.95 nm,which helps differentiate diffusion pores and seepage fractures.The D values show an asymmetric U-shaped trend as the coal metamorphism increases,demonstrating that coalification greatly affects the pore fractal dimensions.The three fractal dimensions can characterize the difference in coal microstructure and reflect their influence on gas adsorption ability.Langmuir volume(V_(L))has an evident and positive correlation with Dsvalues,whereas Langmuir pressure(P_(L))is mainly affected by the combined action of Dvand Dp.This study will provide valuable knowledge for the appraisal of coal seam gas reservoirs of differently ranked coals.
基金supported by the National Natural Science Foundation of China(52172091,52172295)Defense Industrial Technology Development Program(JCKY2023605C002)+4 种基金Frontier Leading Technology Basic Research Major Project of Jiangsu Province(SBK2023050110)the National Key Laboratory on Electromagnetic Environmental Effects and Electro-optical Engineering(NO.61422062301)the Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory(ZHD202305)the Opening Project of Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology(ASMA202303)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX23_0371).
文摘Advanced chemical engineering for simultaneous modulation of nanomaterial morphology, defects, interfaces, and structure to enhance electromagnetic and microwave absorption (MA) performance. However, accurately distinguishing the MA contributions of different scale factors and tuning the optimal combined effects remains a formidable challenge. This study employs a synergistic approach combining template protection etching and vacuum annealing to construct a controlled system of micrometer-sized cavities and amorphous carbon matrices in metal-organic framework (MOF) derivatives. The results demonstrate that the spatial effects introduced by the hollow structure enhance dielectric loss but significantly weaken impedance matching. By increasing the proportion of amorphous carbon, the balance between electromagnetic loss and impedance matching can be effectively maintained. Importantly, in a suitable graphitization environment, the presence of oxygen vacancies in amorphous carbon can induce significant polarization to compensate for the reduced conductivity loss due to the absence of sp2 carbon. Through the synergistic effects of morphology and composition, the samples exhibit a broader absorption bandwidth (6.28 GHz) and stronger reflection loss (−61.64 dB) compared to the original MOF. In conclusion, this study aims to elucidate the multiscale impacts of macroscopic micro-nano structure and microscopic defect engineering, providing valuable insights for future research in this field.
基金funded by the Joint Fund for Regional Innovation and Development of National Natural Science Foundation of China(U21A20143)the National Science Fund for Excellent Young Scholars(52322607)the Excellent Youth Foundation of Heilongjiang Scientific Committee(YQ2022E028)。
文摘Improving the volumetric energy density of supercapacitors is essential for practical applications,which highly relies on the dense storage of ions in carbon-based electrodes.The functional units of carbon-based electrode exhibit multi-scale structural characteristics including macroscopic electrode morphologies,mesoscopic microcrystals and pores,and microscopic defects and dopants in the carbon basal plane.Therefore,the ordered combination of multi-scale structures of carbon electrode is crucial for achieving dense energy storage and high volumetric performance by leveraging the functions of various scale structu re.Considering that previous reviews have focused more on the discussion of specific scale structu re of carbon electrodes,this review takes a multi-scale perspective in which recent progresses regarding the structureperformance relationship,underlying mechanism and directional design of carbon-based multi-scale structures including carbon morphology,pore structure,carbon basal plane micro-environment and electrode technology on dense energy storage and volumetric property of supercapacitors are systematically discussed.We analyzed in detail the effects of the morphology,pore,and micro-environment of carbon electrode materials on ion dense storage,summarized the specific effects of different scale structures on volumetric property and recent research progress,and proposed the mutual influence and trade-off relationship between various scale structures.In addition,the challenges and outlooks for improving the dense storage and volumetric performance of carbon-based supercapacitors are analyzed,which can provide feasible technical reference and guidance for the design and manufacture of dense carbon-based electrode materials.
基金Projects(52222404,52074212)supported by the National Natural Science Foundation of ChinaProject(2023-LL-QY-07)supported by the Two-chain Integration Key Projects in Shaanxi Province,China。
文摘As the second most important solid waste produced by coal-fired power plants,the improper management of coal-fired slag has the potential to result in environmental pollution.It is therefore imperative that high-value utilization pathways for coal-fired slag should be developed.In this study,modified magnesium slag(MMS),produced by a magnesium smelter,was selected as the alkali activator.The activated silica-aluminum solid wastes,namely coal-fired slag(CFS)and mineral powder(MP),were employed as pozzolanic materials in the preparation of alkali-activated cementitious materials.The alkali-activated cementitious materials prepared with 50 wt%MMS,40 wt%CFS and 10 wt%MP exhibited favorable mechanical properties,with a compressive strength of 32.804 MPa in the paste sample cured for 28 d.Then,the activated silica-aluminum solid waste consisting of CFS-MP generated a significant amount of C-S(A)-H gels,AFt,and other products,which were observed to occupy the pore structure of the specimen.In addition,the secondary hydration reaction of CFS-MP occurs in high alkalinity environments,resulting in the formation of a mutually stimulated and promoted reaction system between CFS-MP and MMS,this will subsequently accelerate the hydrolysis reaction of MMS.It is important to emphasize that the amount of MMS in alkali-activated cementitious materials must be strictly regulated to avert the potential issue of incomplete depolymerization-repolymerization of active silica-aluminum solid waste containing CFS-MP.This in turn could have a deleterious impact on the late strength of the cementitious materials.The aim of this work is to improve the joint disposal of MMS,CFS and MP and thereby provide a scientific basis for the development of environmentally friendly and low-carbon modified magnesium slag alkali-activated coal-fired slag based cementitious materials for mine backfilling.
基金supported by Ningxia Natural Science Foundation Innovative Group Project(2023AAC01001)the Postdoctoral Research Excellence Funding Project of Zhejiang Province ofChina(ZJ2023135).
文摘This study systematically investigated the effects of different gas stove structures on flame combustion characteristics using spectral diagnostic techniques,aiming to provide optimized design guidelines for clean energy applications.To explore the combustion behaviors of various gas stove structures,UV cameras,high-speed cameras,and K-type thermocouples were employed to measure parameters such as flame OH radicals(OH*),flame morphology,pulsation frequency,flame temperature,and heat flux.The results demonstrate that flame stability was achieved at an inner/outer cover flow rate ratio of 0.5/4.0 L/min,beyond which further flow rate increases led to reduced combustion efficiency.Compared to covered stoves,top-uncovered stove exhibited 5.5%and 12.4%higher temperatures at the inner and outer covers,respectively,along with a 35%increase in heat flux.Comprehensive analysis revealed an approximately 20%enhancement in overall flame intensity.The experimental results show that top-uncovered gas stoves exhibit higher flame intensity,greater combustion efficiency,and overall higher stove efficiency.In contrast,covered gas stoves feature a more controllable and stable flame with a gentler temperature rise.This study underscores the importance of optimizing gas stove designs to enhance combustion efficiency and reduce emissions,contributing to the transition from fossil fuels to renewable energy sources and promoting sustainable development.
基金Open Project of Shanghai Key Laboratory of Lightweight Composite,China(No.2232021A4-04)。
文摘Double-shaft-driven needle punching machine is a specialized equipment designed for processing C/C crucible preforms.Its main needle punching module is operated by two sets of reciprocating crank-slider mechanisms.The intense vibration during needle punching not only generates huge noise,but also substantially reduces the quality of the preform.It is imperative to perform a dynamic analysis and optimization of the entire needle punching machine.In this paper,the three-dimensional(3D)model of the entire double-shaft-driven needle punching machine for C/C crucible preforms is established.Based on the modal analysis theory,the modal characteristics of the needle punching machine under various operating conditions are analyzed and its natural frequencies and vibration modes are determined.The harmonic response analysis is then employed to obtain the amplitude of the needle plate at different frequencies,and the structural weak points of the needle punching machine are identified and improved.The feasibility of the optimized scheme is subsequently reevaluated and verified.The results indicate that the first six natural frequencies of the machine increase,and the maximum amplitude of the needle plate decreases by 70.3%.The enhanced dynamic characteristics of the machine significantly improve its performance,enabling more efficient needle punching of C/C crucible preforms.
文摘This study investigates the Benxi Formation sandstone reservoirs in the Yanchuan East Block of the Ordos Basin,employing an integrated approach that includes core observation,thin-section analysis,scanning electron microscopy,high-pressure mercury intrusion,and petrophysical testing to systematically evaluate reservoir petrographic features and pore structures.Results reveal that Benxi Formation sandstones predominantly comprise quartz sandstones,lithic quartz sandstones,and lithic sandstones,characterized by high quartz content,widespread volcanic lithic fragments,moderately well-sorted grains,and complex cement types.Pore types are dominated by residual intergranular and dissolution pores,with minor intracrystalline pores and fractures;overall porosity ranges from 0.17%to 9.07%(average 4.74%),and permeability from 0.01 to 6.05 mD,classifying them as ultra-low porosity and tight reservoirs.High-pressure mercury intrusion indicates microfine throats as the primary structure,divisible into four distinct types.Diagenetically,compaction and cementation are the main drivers of primary pore loss and reservoir tightening,whereas late-stage dissolution partially ameliorates pore networks.Overall,Benxi Formation sandstone reservoirs exhibit pervasive densification but localized favorable pore assemblages and connectivity,facilitating hydrocarbon migration and accumulation.These findings advance understanding of Upper Paleozoic tight sandstone reservoir characteristics and aid in predicting sweet spots.
基金supported by the National Science and Technology Major Project(No.J2019-VI-0006-0120)the National Natural Science Foundation of China(No.52074092).
文摘Upon approaching 850℃,the GH4151 alloy exhibits diminished high-temperature strength,primarily attributed to the disruption of γ′phase coherence at elevated temperatures,which reduces its strengthening contribution.Tantalum(Ta)additions enhance the stability of the γ′phase but introduce processing challenges,including pronounced solidification segregation,the formation of secondary phases,and increased susceptibility to cracking during processing.The influence of Ta content on elemental segregation,solidification microstructure,phase precipitation kinetics,and hot deformation behaviour in GH4151 was systematically investigated.Processing windows derived from the dynamic materials model(DMM)and microstructural evolution under varying thermomechanical conditions are further examined.Key findings reveal the severe Ta segregation(segregation coefficient K≈1.608);Ta promotes γ/γ′eutectic and η phase formation,increasing γ′phase volume fraction from 54% to approximately 63%;and increased Ta content elevates flow stress and progressively narrows the DMM-defined processing window;optimized thermomechanical processing parameters(elevated temperatures and strain rates)enhance recrystallization kinetics and hot workability,thereby mitigating cracking propensity.
基金Supported by National Natural Science Foundation of China(Grant No.51675180)National Key Basic Research Program of China(973 Program,Grant No.2013CB037503)
文摘To improve the adaptability of TBMs in diverse geological environments,this paper proposes a reconfigurable Type-V thrust mechanism(V-TM)with rearrangeable working states,in which structural stiffness can be automatically altered during operation.Therefore,millions of configurations can be obtained,and thousands of instances of working status per configuration can be set respectively.Nonetheless,the complexity of configurations and diversity of working states contributes to further complications for the structural stiffness algorithm.This results in challenges such as difficulty calculating the payload compliance index and the environment adaptability index.To solve this problem,we use the configuration matrix to describe the relationship between propelling jacks under reconfiguration and adopt pattern vectors to describe the working state of each hydraulic cylinder.Then,both the dynamic compatible equation between propeller forces of the hydraulic cylinders and driving forces,and the kinematic harmonizing equation between the hydraulic cylinder displacements and their deformations are established.Next,we derive the stiffness analytical equation using Hooke’s law and the Jacobian Matrix.The proposed approach provides an effective algorithm to support structural rigidity analysis,and lays a solid theoretical foundation for calculating the performance indexes of the V-TM.We then analyze the rigidity characteristics of typical configurations under different working states,and obtain the main factors affecting structural stiffness of the V-TM.The results show the deviation degree of structural parameters in hydraulic cylinders within the same group,and the working status of propelling jacks.Finally,our constructive conclusions contribute valuable information for matching and optimization by drawing on the factors that affect the structural rigidity of the V-TM.
文摘The effect of application of pig manure (PM) on the structural characteristics of humic acids (HAs) of brown soil was studied in field and incubation experiments. The results showed that the number-average molecular weights (Mn), the ratios of C/ H, C/ N and O/C, the contents of carboxyl and phenolic hydroxyl groups, the content ofaromatic C, the values of E2, E4and λ Exmax of HAs all decreased; whereas, the contents of alkyl C and O-alkyl C, the ratio of carboxyl to phenolic hydroxyl groups, the degree of oxidation stability, the absorption intensity at 285 mμ (UV), and 2920cm-1 of HAs increased after the application of PM. The above results indicated that the molecular structure of HAs tended to be more aliphatic and simpler after the application of PM.
基金AECC Commercial Aircraft Engine Co.,LTD for providing the financial support。
文摘In the design process of advanced aero-engines,it is necessary to carry out an effective analysis method between structural features and mechanical characteristics for a better structural optimization.Based on the structural composition and functions of aero-engines,the concept and contents of structural efficiency can reflect the relation between structural features and mechanical characteristics.In order to achieve the integrated design of structural and mechanical characteristics,one quantitative analysis method called Structural Efficiency Assessment Method(SEAM)was put forward.The structural efficiency coefficient was obtained by synthesizing the parameters to quantitatively evaluate the aero-engine structure design level.Parameterization method to evaluate structural design quality was realized.After analyzing the structural features of an actual dual-rotor system in typical high bypass ratio turbofan engines,the mechanical characteristics and structural efficiency coefficient were calculated.Structural efficiency coefficient of high-pressure rotor(0.43)is higher than that of low-pressure rotor(0.29),which directly shows the performance of the former is better,there is room for improvement in structural design of the low-pressure rotor.Thus the direction of structural optimization was pointed out.The applications of SEAM shows that the method is operational and effective in the evaluation and improvement of structural design.
基金funded by the National Key Research and Development Program‘Deep Land Resources Exploration and Exploitation’special project(2017YFC0603106)the Project of Science and Technology Department of the Southwest Oil and Gas Field Company,Petrochina(20210301-02)。
文摘Based on 2D and 3D seismic data,the latest drilling data and field outcrop data of the northern slope of the Central Sichuan paleo-uplift,the structural analysis method is used to analyze unconformity development characteristics and fault characteristics during the key structural transformation period,discussing the influence of the structural characteristics on the hydrocarbon accumulation of deep carbonate rocks.The results show that:(1)The two key unconformities of the Tongwan and Caledonian periods were primarily developed in deep carbonate rocks.Firstly,Tongwan’s unconformities are characterized by regional disconformities between the second and third members of the Dengying Formation,the top formation of the Sinian and the lower Cambrian,strips of which zigzag through the north and south sides of the study area.Secondly,the Caledonian unconformity is characterized by a regional unconformable contact between the lower Permian and the ower Paleozoic strata.From NE to SW,the age of the strata,which were subject to erosion,changes from new to old,the denudation distribution showing as a nose-shaped structure which inclines towards the ENE.(2)Boundary fault and transtensional strike-slip faults developed in the Sinian to Paleozoic strata.In profile,there are three types of structural styles:steep and erect,flower structures,’Y’and reversed’Y’type faults.In plane view,the Sinian developed extensional boundary faults extending in an almost NS direction,strike-slip faults developing and extending linearly in approximately EW,WNW and NE strikes in the Cambrian,with characteristically more in the south and less in the north.(3)The faults in the northern slope show obvious zonal deformations in transverse view as well as significant stages and stratified activity in a longitudinal direction.Among them,the activity of faults in the Sinian was the strongest,followed by the activity in the Cambrian period,the activity intensity of faults in the Permian period being the weakest.This fault activity can be divided into four periods:Sinian,Cambrian-Permian,the early Indosinian period and the late Indosinian-Himalayan period,the transtensional strikeslip faults being the products of oblique extensions of pre-existing weak zones in the Xingkai and Emei taphrogenesis,with a particular inheritance in the main faults.(4)Combined with hydrocarbon accumulation factors,it is considered that the epigenetic karstification of the Tongwan and Caledonian unconformities in the northern slope controlled the formation and distribution of carbonate karst reservoirs over a large area,also acting as a good pathway for oil and gas migration.The extensional faults developed at the margin of the NS trending rift,controlling the sag-platform sedimentary pattern in the Dengying Formation of the Sinian.Strike-slip faults in NE,WNW and ENE directions may control the microgeomorphological pattern inside the platform and intensify the differential distribution of grain beach facies.The multi-stage hereditary activity of strike-slip faults not only improved the porosity and permeability of the reservoirs,but also acted as the main channel of oil and gas migration,providing favorable conditions for the development of the current multi-layer gasbearing scenario in the northern slope of the Central Sichuan Basin.
基金Projects(50774093,50490274) supported by the National Natural Science Foundation of China
文摘There are two mechanisms of the coarse surface asperity resistance effect and rubbing resistance effect in the course of the soft rock structural surface creep,of which the former plays a dominant role in hindering the deformation in the starting creep phase,so that the structural surface creep usually displays the strong surface roughness effect,and so does the latter when the asperities in the coarse surface were fractured by shearing.Under the low stress condition,there are only two phases of the decelerating creep and the constant creep for the soft rock structural surface,and as the stress increases and overcomes the rubbing resistance,the accelerating creep failure of the structural surface will happen suddenly.Therefore,a multiple rheological model,which combines the nonlinear NEWTON body(NN) of a certain mass and the empirical plastic body(EM) with the classical SAINT VENANT body,NEWTON body,KELVIN body and HOOKE body,could be used to comprehensively describe the creep characteristics of the soft rock structural surface.Its mechanical parameter values will vary owing to the different surface roughness of the structural surface.The parameters of GH,GK and ηL are positively linearly correlative to the surface roughness.The surface roughness and m are negative exponential function correlation.The long-term strength τS is positively correlative to the surface roughness.
基金supported by the National Natural Science Foundation of China(Grant Nos.11272048,51239006,and 11034010)the European Commission MarieCurie Actions(Grant No.IRSES-294976)the National Basic Research Program of China(Grant No.2010CB731504)
文摘Two-dimensional disordered granular assemblies composed of 2048 polydispersed frictionless disks are simulated using the discrete element method. The height of the first peak of the pair correlation function, gl, the local and global bond orientational parameters ψ6^1 and ψ6^g, and the fluctuations of these parameters decrease with increasing polydispersity s, implying the transition from a polycrystalline state to an amorphous state in the system. As s increases, the peak position of the boson peak aJBp shifts towards a lower frequency and the intensity of the boson peak D（ωBP）/ωBp increases, indicating that the position and the strength of the boson peak are controlled by the polydispersity of the system. Moreover, the inverse of the boson peak intensity ωBP/D（ωBP）, the shear modulus G, and the basin curvature SIS all have a similar dependence on s, implying that the s dependence of the vibrational density of states at low frequencies likely originates from the s dependence of the basin curvature.
基金Supported by Nation Youth Science Foundation of China(Grant No.51505315)Collaboration Innovation Center of Taiyuan Heavy Machinery Equipment and Shanxi Provincial Natural Science Foundation of China(Grant No.201701D221135)Innovative Project of Graduate Education in Shanxi Province of China(Grant No.2016BY132)
文摘When an output curve force is applied to a horizontal servo cylinder with a heavy load, the piston rod bears a dynamic partial load based on the installation and load characteristics, which significantly a ects the frequency response and control accuracy of the servo cylinder. Based on this partial load, increased friction can lead to cylinder bore scu ng, leakage, lack of output power, or even system failure. In this paper, a novel asymmetric static-pressure support structure is proposed based on the principle of hydrostatic support. The radial component force of a dynamic partial load is balanced by cooperation between the support oil cushion of the variable hydraulic pressure support structure, oil cushion of the supportive force, and the damper. Adaptive control of the servo cylinder piston rod, guide sleeve, and piston, as well as the cylinder oil film friction between lubricated surfaces is achieved. In this paper, theoretical design and analysis of the traditional hydrostatic bearing structure and novel structure are presented. A hydraulic dynamic shear scissor is used as a research target to derive a structural dynamic model. Comparative simulations are performed using Matlab Simulink. Additionally, flow field analysis of the novel structure is performed, which verifies the rationality and feasibility of the proposed structure and system.
