A deep-sea mining riser is a crucial component of the system used to lift seafloor mineral resources to the vessel.It is prone to damage and failure because of harsh environmental conditions and internal fluid erosion...A deep-sea mining riser is a crucial component of the system used to lift seafloor mineral resources to the vessel.It is prone to damage and failure because of harsh environmental conditions and internal fluid erosion.Furthermore,damage can impact the response characteristics of the riser,but varying environmental loadings easily mask it.Thus,distin-guishing between riser damage and environmental effects poses a considerable challenge.To address this issue,a cantilevered model is created for a deep-sea mining riser via the concentrated mass method,and a time-domain analytical strategy is developed.The vortex-induced vibration(VIV)response characteristics of the riser are initially examined,considering various damage conditions and flow velocities.The study results revealed four primary observations:(a)effective tension can serve as a reliable indicator for identifying damage at lower velocities;(b)there are noticeable differences in displacement between the healthy and damaged risers in the in-line direction rather than the cross-flow direction;(c)frequency characteristics can more effectively distinguish the damage conditions at high flow velocities,with the mean square frequency and frequency variance being more effective than the centroid frequency and root variance frequency;(d)displacement differences are more sensitive to damage occurring near the top and bottom of the riser,while both velocity variations and structural damage can influence displacements,especially in regions between modal nodes.The vibrational behavior and damage indicators are clarified for structural health monitoring of deep-sea mining risers during lifting operations.展开更多
Fluid-structure interaction(FSI)of gas-liquid two-phase fow in the horizontal pipe is investigated numerically in the present study.The volume of fluid model and standard k-e turbulence model are integrated to simulat...Fluid-structure interaction(FSI)of gas-liquid two-phase fow in the horizontal pipe is investigated numerically in the present study.The volume of fluid model and standard k-e turbulence model are integrated to simulate the typical gas-liquid two-phase fow patterns.First,validation of the numerical model is conducted and the typical fow patterns are consistent with the Baker chart.Then,the FSI framework is established to investigate the dynamic responses of the interaction between the horizontal pipe and gas-liquid two-phase fow.The results show that the dynamic response under stratified fow condition is relatively flat and the maximum pipe deformation and equivalent stress are 1.8 mm and 7.5 MPa respectively.Meanwhile,the dynamic responses induced by slug fow,wave fow and annular fow show obvious periodic fuctuations.Furthermore,the dynamic response characteristics under slug flow condition are maximum;the maximum pipe deformation and equivalent stress can reach 4mm and 17.5 MPa,respectively.The principal direction of total deformation is different under various flow patterns.Therefore,the periodic equivalent stress will form the cyclic impact on the pipe wall and affect the fatigue life of the horizontal pipe.The present study may serve as a reference for FSI simulation under gas-liquid two-phase transport conditions.展开更多
Slug flow or high GVF(Gas Volume Fraction)conditions can cause pressure disturbance waves and alternating loads at the boundary of mechanical seals for multiphase pumps,endangering the safety of multiphase pump units....Slug flow or high GVF(Gas Volume Fraction)conditions can cause pressure disturbance waves and alternating loads at the boundary of mechanical seals for multiphase pumps,endangering the safety of multiphase pump units.The mechanical seal model is simplified by using periodic boundary conditions and numerical calculations are carried out based on the Zwart-Gerber-Belamri cavitation model.UDF(User Define Function)programs such as structural dynamics equations,alternating load equations,and pressure disturbance equations are embedded in numerical calculations,and the dynamic response characteristics of mechanical seal are studied using layered dynamic mesh technology.The results show that when the pressure disturbance occurs at the inlet,as the amplitude and period of the disturbance increase,the film thickness gradually decreases.And the fundamental reason for the hysteresis of the film thickness change is that the pressure in the high-pressure area cannot be restored in a timely manner.The maximum value of leakage and the minimum value of axial velocity are independent of the disturbance period and determined by the disturbance amplitude.The mutual interference between enhanced waves does not have a significant impact on the film thickness,while the front wave in the attenuated wave has a promoting effect on the subsequent film thickness changes,and the fluctuation of the liquid film cavitation rate and axial velocity under the attenuated wave condition deviates from the initial values.Compared with pressure disturbance conditions,alternating load conditions have a more significant impact on film thickness and leakage.During actual operation,it is necessary to avoid alternating load conditions in multiphase pump mechanical seals.展开更多
In this study,a comprehensive rolling mill vibration test program was designed,including specific test conditions and a test system.The analysis of measured signals reveals the vibration response characteristics and t...In this study,a comprehensive rolling mill vibration test program was designed,including specific test conditions and a test system.The analysis of measured signals reveals the vibration response characteristics and their evolution at different gauge points in the finishing mill.This is particularly evident during abnormal rolling,where the signals highlight the characteristics of abnormal responses and vibration intensities.Abnormal vibrations during the rolling process mainly occur when the strip thickness is less than 2.5 mm,and at the rolling speed-up stage,the strong abnormal vibration occurs at each measuring point on the F2 transmission side.The maximum vibration intensity of the backup roll’s bearing seat is 17 mm/s.As the rolling progresses,the stress on the bolts changes.The strip thickness is negatively correlated with the peak values of bite and tail-flick impacts.The vibration characteristics vary with the strip thickness and the process state.展开更多
There exist different response characteristics in the resistivity measurements of dual laterolog （DLL） and logging while drilling （LWD） electromagnetic wave propagation logging in highly deviated and horizontal we...There exist different response characteristics in the resistivity measurements of dual laterolog （DLL） and logging while drilling （LWD） electromagnetic wave propagation logging in highly deviated and horizontal wells due to the difference in their measuring principles. In this study, we first use the integral equation method simulated the response characteristics of LWD resistivity and use the three dimensional finite element method （3D-FEM） simulated the response characteristics of DLL resistivity in horizontal wells, and then analyzed the response differences between the DLL and LWD resistivity. The comparative analysis indicated that the response differences may be caused by different factors such as differences in the angle of instrument inclination, anisotropy, formation interface, and mud intrusion. In the interface, the curves of the LWD resistivity become sharp with increases in the deviation while those of the DLL resistivity gradually become smooth. Both curves are affected by the anisotropy although the effect on DLL resistivity is lower than the LWD resistivity. These differences aid in providing a reasonable explanation in the horizontal well. However, this can also simultaneously lead to false results. At the end of the study, we explain the effects of the differences in the interpretation of the horizontal well based on the results and actual data analysis.展开更多
A 6 MW spar-type floating offshore wind turbine （FOWT） model is put forward and a fully coupled aero-hydro-servo-elastic time domain model is established in the fatigue, aerodynamics, structures and turbulence （FAS...A 6 MW spar-type floating offshore wind turbine （FOWT） model is put forward and a fully coupled aero-hydro-servo-elastic time domain model is established in the fatigue, aerodynamics, structures and turbulence （FAST） code. Influence rules of wind 10ad and wave load on the characteristics of 6 MW spar-type FOWT are investigated. Firstly, validation of the model is carried out and a satisfactory result is obtained. The maximal deviations of rotor thrust and power between simulation results and reference values are 4.54% and -2.74%, respectively. Then the characteristics, including rotor thrust, rotor power, out-of-plane blade deflection, tower base fore-aft bending moment, and mooring line tension, are researched. The results illustrate that the mean value of dynamic response characteristics is mainly controlled by the wind-induced action. For characteristics of tower base fore-aft bending moment and platform pitch motion, the oscillation is dominated by the wave-induced action during all conditions considered. For characteristics of out-of-plane blade tip deflection and mooring line tension, the oscillation is commanded by combination effect of wave and wind loads when the wind speed is lower than the rated wind speed （hereinafter referred to as below rated wind speed） and is controlled by the wave-induced action when the wind speed is higher than the rated wind speed （hereinafter referred to as above rated wind speed）. As to the rotor thrust and power, the oscillation is dominated by the wind induced action at below rated wind speed and by the combination action of wind and wave loads at above rated wind speed. The results should be useful to the detailed design and model basin test of the 6 MW spar-type FOWT.展开更多
To investigate the stress response characteristics and shear stress transfer mechanism of BFRP(basalt fiber reinforced plastics)anchors under rainfall conditions and to explore the reinforcement effect of BFRP anchors...To investigate the stress response characteristics and shear stress transfer mechanism of BFRP(basalt fiber reinforced plastics)anchors under rainfall conditions and to explore the reinforcement effect of BFRP anchors,a comparative indoor physical model test was conducted in this study using loess mudstone slope as a typical case,and multi-attribute response data,such as slope displacement,BFRP anchor strain and axial force,were obtained.Based on the variation law of slope displacement,it can be concluded that the deformation displacement of the slope on the side reinforced by BFRP anchors is smaller than that of slopes reinforced with steel anchors;the bearing capacity of BFRP anchor is given priority in time,and the anchoring effect of BFRP anchor at the top of the slope is given priority,and the axial force value of anchor is characterized by a surface amplification effect in space;the axial force is higher around the anchor head and tends to decay as a negative exponential function as the anchor extends in the direction of the interior of the slope;the shear stress of BFRP anchor and anchorage body are unevenly distributed along the axial direction,with the maximum value occurring in the free section near the slope surface and decreases as the BFRP anchor extends towards the interior of the slope.These results can provide a theoretical basis for the optimal design of BFRP anchors.展开更多
The high-power microwave(HPM)effect heats solar cells,which is an important component of a satellite.This creates a serious reliability problem and affects the normal operation of a satellite.In this paper,the differe...The high-power microwave(HPM)effect heats solar cells,which is an important component of a satellite.This creates a serious reliability problem and affects the normal operation of a satellite.In this paper,the different HPM response characteristics of two kinds of solar cells are comparatively researched by simulation.The results show that there are similarities and differences in hot spot distribution and damage mechanisms between both kinds of solar cell,which are related to the amplitude of HPM.In addition,the duty cycle of repetition frequency contributes more to the temperature accumulation of the solar cells than the carrier frequency.These results will help future research of damage assessment technology,reliability enhancement and the selection of materials for solar cells.展开更多
Potash deposition is the result of final phase of brine sedimentary evolution,it’s a limited distribution and easily soluble mineral,it is difficult to find the features on the ground,therefore the prospecting is ext...Potash deposition is the result of final phase of brine sedimentary evolution,it’s a limited distribution and easily soluble mineral,it is difficult to find the features on the ground,therefore the prospecting is extremely tough.展开更多
The rapid development of traffic engineering in cold regions and its consequent problems need to be considered.In this paper,the dynamic response characteristics of the tunnel portal section in cold regions with harmo...The rapid development of traffic engineering in cold regions and its consequent problems need to be considered.In this paper,the dynamic response characteristics of the tunnel portal section in cold regions with harmonic load acting on the lining were studied in the frequency domain.The lining is in close contact with the frozen soil,and there is relative movement between the frozen and unfrozen soil due to the phase change.The analytical solution of the vibration of tunnel portal section caused by the harmonic load acting on the lining was derived under the consideration of the anisotropy frost heave of overlying soil.Based on the continuity conditions and boundary conditions,the undetermined coefficients were obtained,and the analytical solutions for different medium displacements and stresses of the cold-region tunnel system were acquired.The vertical pressure coefficient was equivalently simplified as a variable that could be used to replace the thickness of the overlying soil above the tunnel.The analysis of the parameter model shows that the change of the medium parameters(lining,frozen,and unfrozen soil)affects the circumferential stresses,the radial displacements and their peak frequencies of the soil.For example,the increase of density ratio of tunnel lining to frozen soil decreases the radial stresses of the frozen and unfrozen soil;the increase of volumetric frost heaving strain of the frozen soil increases the radial displacements of the frozen surface and decreases the stability of the frozen surface;the increasing of thickness of the frozen soil significantly reduces the radial displacement of unfrozen soil at dimensionless radius η=4.5 compared with that of frozen soil at η=1.5.展开更多
In this paper the problem of a circular beam subjected to radial impact by a rigid mass at its lip in its own plane is investigaleil on the basis of rigid-perfectly plastic assumption. The analytical solution of the p...In this paper the problem of a circular beam subjected to radial impact by a rigid mass at its lip in its own plane is investigaleil on the basis of rigid-perfectly plastic assumption. The analytical solution of the particle velocities is obtained as the junction of travelling plastic hinge location. Ky analysing the solution, some special properties oj circular beam problem are found.展开更多
The excessive deformation of deep-sea sediments caused by the vibration of the mining machine will adversely affect the efficiency and safety of mining.Combined with the deep-sea environment,the coupled thermo-hydro-m...The excessive deformation of deep-sea sediments caused by the vibration of the mining machine will adversely affect the efficiency and safety of mining.Combined with the deep-sea environment,the coupled thermo-hydro-mechanical problem for saturated porous deep-sea sediments subject to the vibration of the mining vehicle is investigated.Based on the Green-Lindsay(G-L)generalized thermoelastic theory and Darcy’s law,the model of thermo-hydro-mechanical dynamic responses for saturated porous deep-sea sediments under the vibration of the mining vehicle is established.We obtain the analytical solutions of non-dimensional vertical displacement,excess pore water pressure,vertical stress,temperature,and change in the volume fraction field with the normal mode analysis method,and depict them graphically.The normal mode analysis method uses the canonical coordinate transformation to solve the equation,which can quickly decouple the equation by ignoring the modal coupling effect on the basis of the canonical mode.The results indicate that the vibration frequency has obvious influence on the vertical displacement,excess pore water pressure,vertical stress,and change in volume fraction field.The loading amplitude has a great effect on the physical quantities in the foundation,and the changes of the physical quantities increase with the increase in loading amplitude.展开更多
For anti-jamming and anti-countermeasure techniques of the sonar receiver, the response characteristics of the automatic gain control （AGC） circuit and the survivability of the prime circuit under strong interferenc...For anti-jamming and anti-countermeasure techniques of the sonar receiver, the response characteristics of the automatic gain control （AGC） circuit and the survivability of the prime circuit under strong interference are analyzed by simulations and experiments. An AGC simulation model based on the voltage control amplifier VCA810 prototype is proposed. Then static and dynamic simulations are realized with single frequency signal and linear frequency modulated （LFM） signal commonly used in the active sonar. Based on intense sound pulse （ISP） interference experiments, the real-time response characteristics of each module of the receiver are studied to verify the correctness of the model as well as the simulation results. Simulation and experiment results show that, under 252 dB/20 μs ISP interference, the specific sonar receiver will produce sustained cut top oscillation above 30 ms, which may affect the receiver and block the regular sonar signal.展开更多
Given is the experiment results in which the laser pulses of 1 046 nm and 532 nm are used to trigger the semi-insulation GaAs photoconductive semiconductor switch(PCSS) with an electrode distance of 4 mm. And made is ...Given is the experiment results in which the laser pulses of 1 046 nm and 532 nm are used to trigger the semi-insulation GaAs photoconductive semiconductor switch(PCSS) with an electrode distance of 4 mm. And made is an analysis of the switchs photovoltaic response characteristics under the high gain mode when the biased field is bigger than the Geng effect field. Also a theory is presented that the main reason for the photovoltaic pulse response delay is the transmission of charge domain, caused by the presence of EL2 energy level in the chip material. Finally, the transmission time of charge domain is calculated and a result that inosculates with the experiment is attained.展开更多
The coupling effects of rainfall,earthquake,and complex topographic and geological conditions complicate the dynamic responses and disasters of slope-tunnel systems.For this,the large-scale shaking table tests were ca...The coupling effects of rainfall,earthquake,and complex topographic and geological conditions complicate the dynamic responses and disasters of slope-tunnel systems.For this,the large-scale shaking table tests were carried out to explore the dynamic responses of steep bedding slope-tunnel system under the coupling effect of rainfall and earthquake.Results show that the slope surface and elevation amplification effect exhibit pronounced nonlinear change caused by the tunnel and weak interlayers.When seismic wave propagates to tunnels,the weak interlayers and rock intersecting areas present complex wave field distribution characteristics.The dynamic responses of the slope are influenced by the frequency,amplitude,and direction of seismic waves.The acceleration amplification coefficient initially rises and then falls as increasing seismic frequency,peaking at 20 Hz.Additionally,the seismic damage process of slope is categorized into elastic(2-3 m/s^(2)),elastoplastic(4-5 m/s^(2))and plastic damage stages(≥6.5 m/s^(2)).In elastic stage,ΔMPGA(ratio of acceleration amplification factor)increases with increasing seismic intensity,without obvious strain distribution change.In plastic stage,ΔMPGA begins to gradually plummet,and the strain is mainly distributed in the damaged area.The modes of seismic damage in the slope-tunnel system are mainly of tensile failure of the weak interlayer,cracking failure of tunnel lining,formation of persistent cracks on the slope crest and waist,development and outward shearing of the sliding mass,and buckling failure at the slope foot under extrusion of the upper rock body.This study can serve as a reference for predicting the failure modes of tunnel-slope system in strong seismic regions.展开更多
The phonotaxis of bushcrickets demonstrates that they have goodcapability of recognizing conspecific songs and locating the sound source,which bases on complicated auditory mechanisms of the central nervoussystem(CNS)...The phonotaxis of bushcrickets demonstrates that they have goodcapability of recognizing conspecific songs and locating the sound source,which bases on complicated auditory mechanisms of the central nervoussystem(CNS).This article describes the response characteristics of AN3,an auditory ascending neuron in the prothoracic ganglion,and its projec-tions within the brain.The AN3,with a quasi-tonic discharge pattern,has high sensitivity,directionality and ability to encode sound intensity.Therefore,it plays an important role in auditory information processingof CNS.Its projections in the brain are mainly concentrated in the lateralzone of the deutencephalon,where synaptically connecting local auditoryinterneurons in the brain.展开更多
The liquid desiccant air-conditioning system is considered as an energy-efficient alternative to the vapor compression system.The dynamic response characteristics of the system under variable cooling load play an impo...The liquid desiccant air-conditioning system is considered as an energy-efficient alternative to the vapor compression system.The dynamic response characteristics of the system under variable cooling load play an important role in the air temperature and humidity control performance of the system.However,the dynamic response characteristics have not been fully revealed in previous studies.Thus,a dynamic model for a heat pump driven liquid desiccant air-conditioning(HPLDAC)system is established to investigate the dynamic response characteristics of the system in this study.Subsequently,experiments were conducted to validate the accuracy of the dynamic model.The simulation results show a good agreement with the experimental data.The simulation results reveal that evaporating water from the solution is a time-consuming process,compared to adding water to the solution.It spends a long time for the HPLDAC system to decrease the high relative humidity of supply air to a low value,which limits the air temperature and humidity control performance of the system.The upper band for the water replenishing value opening(△φup)is a crucial parameter to improve the limitation.When△φup decreases from 1.0%产to 0.25%,the time consumed to reduce the supply air relative humidity to the new lower set value can be saved by 30.6%.展开更多
We propose an electronic model in Spice, instead of traditional mathematical analysis, for analyzing the performance of ferroelectric liquid crystal （FLC） under various working conditions. Using this equivalent circ...We propose an electronic model in Spice, instead of traditional mathematical analysis, for analyzing the performance of ferroelectric liquid crystal （FLC） under various working conditions. Using this equivalent circuit model,it is easy to simulate and analyze the behavior of an FLC layer in three different typical parameters,including temperature, input light wavelength, and the frequency of driving voltage. We conclude that the response velocity drops as the wavelength increases in the range of visible light, and for the parameter of temperature, the velocity reaches its lowest value when the temperature reaches a certain degree,meanwhile,the frequency of driving voltage exerts important effects on the response velocity only when the frequency is beyond a critical value. Excellent agreement is achieved between simulation and experimental results.展开更多
Seismicity resulting from the near-or in-field fault activation significantly affects the stability of large-scale underground caverns that are operating under high-stress conditions.A comprehensive scientific assessm...Seismicity resulting from the near-or in-field fault activation significantly affects the stability of large-scale underground caverns that are operating under high-stress conditions.A comprehensive scientific assessment of the operational safety of such caverns requires an in-depth understanding of the response characteristics of the rock mass subjected to dynamic disturbances.To address this issue,we conducted true triaxial modeling tests and dynamic numerical simulations on large underground caverns to investigate the impact of static stress levels,dynamic load parameters,and input directions on the response characteristics of the surrounding rock mass.The findings reveal that:(1)When subjected to identical incident stress waves and static loads,the surrounding rock mass exhibits the greatest stress response during horizontal incidence.When the incident direction is fixed,the mechanical response is more pronounced at the cavern wall parallel to the direction of dynamic loading.(2)A high initial static stress level specifically enhances the impact of dynamic loading.(3)The response of the surrounding rock mass is directly linked to the amplitude of the incident stress wave.High amplitude results in tensile damage in regions experiencing tensile stress concentration under static loading and shear damage in regions experiencing compressive stress concentration.These results have significant implications for the evaluation and prevention of dynamic disasters in the surrounding rock of underground caverns experiencing dynamic disturbances.展开更多
Temporal and spatial response characteristics of vegetation NDVI to the variation of temperature and precipitation in the whole year, spring, summer and autumn was analyzed from April 1998 to March 2008 based on the S...Temporal and spatial response characteristics of vegetation NDVI to the variation of temperature and precipitation in the whole year, spring, summer and autumn was analyzed from April 1998 to March 2008 based on the SPOT VGT-NDVI data and daily temperature and precipitation data from 205 meteorological stations in eastern China. The results indicate that as a whole, the response of vegetation NDVI to the variation of temperature is more pronounced than that of precipitation in eastern China. Vegetation NDVI maximally responds to the variation of temperature with a lag of about 10 days, and it maximally responds to the variation of precipitation with a lag of about 30 days. The response of vegetation NDVI to temperature and precipitation is most pronounced in autumn, and has the longest lag in summer. Spatially, the maximum response of vegetation NDVI to the variation of temperature is more pronounced in the northern and middle parts than in the southern part of eastern China. The maximum response of vegetation NDVI to the variation of precipitation is more pronounced in the northern part than in the middle and southern parts of eastern China. The response of vegetation NDVI to the variation of temperature has longer lag in the northern and southern parts than in the middle part of eastern China. The response of vegetation NDVl to the variation of precipitation has the longest lag in the southern part, and the shortest lag in the northern part of eastern China. The response of vegetation NDVI to the variation of temperature and precipitation in eastern China is mainly consistent with other results, but the lag time of vegetation NDVI to the variation of temperature and precipitation has some differences with those results of the monsoon region of eastern China.展开更多
基金financially supported by the National Key Research and Development Program of China(Grant No.2023YFC2811600)the National Natural Science Foundation of China(Grant Nos.52301349 and 52088102)+1 种基金the Qingdao Post-Doctorate Science Fund(No.QDBSH20220202070)the Major Scientific and Technological Innovation Project of Shandong Province(Grant No.2019JZZY010820).
文摘A deep-sea mining riser is a crucial component of the system used to lift seafloor mineral resources to the vessel.It is prone to damage and failure because of harsh environmental conditions and internal fluid erosion.Furthermore,damage can impact the response characteristics of the riser,but varying environmental loadings easily mask it.Thus,distin-guishing between riser damage and environmental effects poses a considerable challenge.To address this issue,a cantilevered model is created for a deep-sea mining riser via the concentrated mass method,and a time-domain analytical strategy is developed.The vortex-induced vibration(VIV)response characteristics of the riser are initially examined,considering various damage conditions and flow velocities.The study results revealed four primary observations:(a)effective tension can serve as a reliable indicator for identifying damage at lower velocities;(b)there are noticeable differences in displacement between the healthy and damaged risers in the in-line direction rather than the cross-flow direction;(c)frequency characteristics can more effectively distinguish the damage conditions at high flow velocities,with the mean square frequency and frequency variance being more effective than the centroid frequency and root variance frequency;(d)displacement differences are more sensitive to damage occurring near the top and bottom of the riser,while both velocity variations and structural damage can influence displacements,especially in regions between modal nodes.The vibrational behavior and damage indicators are clarified for structural health monitoring of deep-sea mining risers during lifting operations.
基金the National Natural Science Foundation of China(No.51779143)the Oceanic Interdisciplinary Program of Shanghai Jiao Tong University(No.SL2020ZD101)the Cultivation of Scientific Research Ability of Young Talents of Shanghai Jiao Tong University(No.19X100040072)。
文摘Fluid-structure interaction(FSI)of gas-liquid two-phase fow in the horizontal pipe is investigated numerically in the present study.The volume of fluid model and standard k-e turbulence model are integrated to simulate the typical gas-liquid two-phase fow patterns.First,validation of the numerical model is conducted and the typical fow patterns are consistent with the Baker chart.Then,the FSI framework is established to investigate the dynamic responses of the interaction between the horizontal pipe and gas-liquid two-phase fow.The results show that the dynamic response under stratified fow condition is relatively flat and the maximum pipe deformation and equivalent stress are 1.8 mm and 7.5 MPa respectively.Meanwhile,the dynamic responses induced by slug fow,wave fow and annular fow show obvious periodic fuctuations.Furthermore,the dynamic response characteristics under slug flow condition are maximum;the maximum pipe deformation and equivalent stress can reach 4mm and 17.5 MPa,respectively.The principal direction of total deformation is different under various flow patterns.Therefore,the periodic equivalent stress will form the cyclic impact on the pipe wall and affect the fatigue life of the horizontal pipe.The present study may serve as a reference for FSI simulation under gas-liquid two-phase transport conditions.
基金the support of the National Natural Science Foundation of China(52372368)。
文摘Slug flow or high GVF(Gas Volume Fraction)conditions can cause pressure disturbance waves and alternating loads at the boundary of mechanical seals for multiphase pumps,endangering the safety of multiphase pump units.The mechanical seal model is simplified by using periodic boundary conditions and numerical calculations are carried out based on the Zwart-Gerber-Belamri cavitation model.UDF(User Define Function)programs such as structural dynamics equations,alternating load equations,and pressure disturbance equations are embedded in numerical calculations,and the dynamic response characteristics of mechanical seal are studied using layered dynamic mesh technology.The results show that when the pressure disturbance occurs at the inlet,as the amplitude and period of the disturbance increase,the film thickness gradually decreases.And the fundamental reason for the hysteresis of the film thickness change is that the pressure in the high-pressure area cannot be restored in a timely manner.The maximum value of leakage and the minimum value of axial velocity are independent of the disturbance period and determined by the disturbance amplitude.The mutual interference between enhanced waves does not have a significant impact on the film thickness,while the front wave in the attenuated wave has a promoting effect on the subsequent film thickness changes,and the fluctuation of the liquid film cavitation rate and axial velocity under the attenuated wave condition deviates from the initial values.Compared with pressure disturbance conditions,alternating load conditions have a more significant impact on film thickness and leakage.During actual operation,it is necessary to avoid alternating load conditions in multiphase pump mechanical seals.
文摘In this study,a comprehensive rolling mill vibration test program was designed,including specific test conditions and a test system.The analysis of measured signals reveals the vibration response characteristics and their evolution at different gauge points in the finishing mill.This is particularly evident during abnormal rolling,where the signals highlight the characteristics of abnormal responses and vibration intensities.Abnormal vibrations during the rolling process mainly occur when the strip thickness is less than 2.5 mm,and at the rolling speed-up stage,the strong abnormal vibration occurs at each measuring point on the F2 transmission side.The maximum vibration intensity of the backup roll’s bearing seat is 17 mm/s.As the rolling progresses,the stress on the bolts changes.The strip thickness is negatively correlated with the peak values of bite and tail-flick impacts.The vibration characteristics vary with the strip thickness and the process state.
基金supported by the National Science and Technology Major Project of China(Nos.2016ZX05014-002-001,2016ZX05002-005-001,and 2017ZX05005-005-005)
文摘There exist different response characteristics in the resistivity measurements of dual laterolog （DLL） and logging while drilling （LWD） electromagnetic wave propagation logging in highly deviated and horizontal wells due to the difference in their measuring principles. In this study, we first use the integral equation method simulated the response characteristics of LWD resistivity and use the three dimensional finite element method （3D-FEM） simulated the response characteristics of DLL resistivity in horizontal wells, and then analyzed the response differences between the DLL and LWD resistivity. The comparative analysis indicated that the response differences may be caused by different factors such as differences in the angle of instrument inclination, anisotropy, formation interface, and mud intrusion. In the interface, the curves of the LWD resistivity become sharp with increases in the deviation while those of the DLL resistivity gradually become smooth. Both curves are affected by the anisotropy although the effect on DLL resistivity is lower than the LWD resistivity. These differences aid in providing a reasonable explanation in the horizontal well. However, this can also simultaneously lead to false results. At the end of the study, we explain the effects of the differences in the interpretation of the horizontal well based on the results and actual data analysis.
基金the National Basic Research Program(973) of China(No.2014CB046205)
文摘A 6 MW spar-type floating offshore wind turbine （FOWT） model is put forward and a fully coupled aero-hydro-servo-elastic time domain model is established in the fatigue, aerodynamics, structures and turbulence （FAST） code. Influence rules of wind 10ad and wave load on the characteristics of 6 MW spar-type FOWT are investigated. Firstly, validation of the model is carried out and a satisfactory result is obtained. The maximal deviations of rotor thrust and power between simulation results and reference values are 4.54% and -2.74%, respectively. Then the characteristics, including rotor thrust, rotor power, out-of-plane blade deflection, tower base fore-aft bending moment, and mooring line tension, are researched. The results illustrate that the mean value of dynamic response characteristics is mainly controlled by the wind-induced action. For characteristics of tower base fore-aft bending moment and platform pitch motion, the oscillation is dominated by the wave-induced action during all conditions considered. For characteristics of out-of-plane blade tip deflection and mooring line tension, the oscillation is commanded by combination effect of wave and wind loads when the wind speed is lower than the rated wind speed （hereinafter referred to as below rated wind speed） and is controlled by the wave-induced action when the wind speed is higher than the rated wind speed （hereinafter referred to as above rated wind speed）. As to the rotor thrust and power, the oscillation is dominated by the wind induced action at below rated wind speed and by the combination action of wind and wave loads at above rated wind speed. The results should be useful to the detailed design and model basin test of the 6 MW spar-type FOWT.
基金the financial support by the National Key R&D Program of China(No.2018YFC1504901)Science and technology development project of China Railway 11th Bureau Group Co.,LTD(20210601)+4 种基金Science and technology development project of China Railway Lanzhou Bureau Group Co.,LTD(2021046-2)Science and technology program of Gansu Province(Grant No.21JR7RA739)Science and Technology Development Project of China Railway Research Institute Co.Ltd(2017-KJ008-Z008-XB)Science and technology development project of China Railway Ninth Bureau Group Co.,Ltd(DLF-ML-JSFW-202109)The Science and Technology Foundation of Guizhou Province(NO.ZK[2022]Key018)。
文摘To investigate the stress response characteristics and shear stress transfer mechanism of BFRP(basalt fiber reinforced plastics)anchors under rainfall conditions and to explore the reinforcement effect of BFRP anchors,a comparative indoor physical model test was conducted in this study using loess mudstone slope as a typical case,and multi-attribute response data,such as slope displacement,BFRP anchor strain and axial force,were obtained.Based on the variation law of slope displacement,it can be concluded that the deformation displacement of the slope on the side reinforced by BFRP anchors is smaller than that of slopes reinforced with steel anchors;the bearing capacity of BFRP anchor is given priority in time,and the anchoring effect of BFRP anchor at the top of the slope is given priority,and the axial force value of anchor is characterized by a surface amplification effect in space;the axial force is higher around the anchor head and tends to decay as a negative exponential function as the anchor extends in the direction of the interior of the slope;the shear stress of BFRP anchor and anchorage body are unevenly distributed along the axial direction,with the maximum value occurring in the free section near the slope surface and decreases as the BFRP anchor extends towards the interior of the slope.These results can provide a theoretical basis for the optimal design of BFRP anchors.
基金This work was supported by the National Natural Science Foundation of China(No.61974116).
文摘The high-power microwave(HPM)effect heats solar cells,which is an important component of a satellite.This creates a serious reliability problem and affects the normal operation of a satellite.In this paper,the different HPM response characteristics of two kinds of solar cells are comparatively researched by simulation.The results show that there are similarities and differences in hot spot distribution and damage mechanisms between both kinds of solar cell,which are related to the amplitude of HPM.In addition,the duty cycle of repetition frequency contributes more to the temperature accumulation of the solar cells than the carrier frequency.These results will help future research of damage assessment technology,reliability enhancement and the selection of materials for solar cells.
文摘Potash deposition is the result of final phase of brine sedimentary evolution,it’s a limited distribution and easily soluble mineral,it is difficult to find the features on the ground,therefore the prospecting is extremely tough.
基金funded by National Natural Science Foundation of China(Grant No.51978039)the Fundamental Research Funds for the Central Universities(Grant No.2021YJS115)。
文摘The rapid development of traffic engineering in cold regions and its consequent problems need to be considered.In this paper,the dynamic response characteristics of the tunnel portal section in cold regions with harmonic load acting on the lining were studied in the frequency domain.The lining is in close contact with the frozen soil,and there is relative movement between the frozen and unfrozen soil due to the phase change.The analytical solution of the vibration of tunnel portal section caused by the harmonic load acting on the lining was derived under the consideration of the anisotropy frost heave of overlying soil.Based on the continuity conditions and boundary conditions,the undetermined coefficients were obtained,and the analytical solutions for different medium displacements and stresses of the cold-region tunnel system were acquired.The vertical pressure coefficient was equivalently simplified as a variable that could be used to replace the thickness of the overlying soil above the tunnel.The analysis of the parameter model shows that the change of the medium parameters(lining,frozen,and unfrozen soil)affects the circumferential stresses,the radial displacements and their peak frequencies of the soil.For example,the increase of density ratio of tunnel lining to frozen soil decreases the radial stresses of the frozen and unfrozen soil;the increase of volumetric frost heaving strain of the frozen soil increases the radial displacements of the frozen surface and decreases the stability of the frozen surface;the increasing of thickness of the frozen soil significantly reduces the radial displacement of unfrozen soil at dimensionless radius η=4.5 compared with that of frozen soil at η=1.5.
文摘In this paper the problem of a circular beam subjected to radial impact by a rigid mass at its lip in its own plane is investigaleil on the basis of rigid-perfectly plastic assumption. The analytical solution of the particle velocities is obtained as the junction of travelling plastic hinge location. Ky analysing the solution, some special properties oj circular beam problem are found.
基金the National Natural Science Foundation of China(No.12072309)the Youth Fund Foundation of Education Bureau of Hunan Province of China(No.19B546)the High-Level Talent Gathering Project in Hunan Province of China(No.2019RS1059)。
文摘The excessive deformation of deep-sea sediments caused by the vibration of the mining machine will adversely affect the efficiency and safety of mining.Combined with the deep-sea environment,the coupled thermo-hydro-mechanical problem for saturated porous deep-sea sediments subject to the vibration of the mining vehicle is investigated.Based on the Green-Lindsay(G-L)generalized thermoelastic theory and Darcy’s law,the model of thermo-hydro-mechanical dynamic responses for saturated porous deep-sea sediments under the vibration of the mining vehicle is established.We obtain the analytical solutions of non-dimensional vertical displacement,excess pore water pressure,vertical stress,temperature,and change in the volume fraction field with the normal mode analysis method,and depict them graphically.The normal mode analysis method uses the canonical coordinate transformation to solve the equation,which can quickly decouple the equation by ignoring the modal coupling effect on the basis of the canonical mode.The results indicate that the vibration frequency has obvious influence on the vertical displacement,excess pore water pressure,vertical stress,and change in volume fraction field.The loading amplitude has a great effect on the physical quantities in the foundation,and the changes of the physical quantities increase with the increase in loading amplitude.
基金supported by the National Natural Science Foundation of China (10974154)the National Innovation Project of China for Undergraduates (101069935)
文摘For anti-jamming and anti-countermeasure techniques of the sonar receiver, the response characteristics of the automatic gain control （AGC） circuit and the survivability of the prime circuit under strong interference are analyzed by simulations and experiments. An AGC simulation model based on the voltage control amplifier VCA810 prototype is proposed. Then static and dynamic simulations are realized with single frequency signal and linear frequency modulated （LFM） signal commonly used in the active sonar. Based on intense sound pulse （ISP） interference experiments, the real-time response characteristics of each module of the receiver are studied to verify the correctness of the model as well as the simulation results. Simulation and experiment results show that, under 252 dB/20 μs ISP interference, the specific sonar receiver will produce sustained cut top oscillation above 30 ms, which may affect the receiver and block the regular sonar signal.
文摘Given is the experiment results in which the laser pulses of 1 046 nm and 532 nm are used to trigger the semi-insulation GaAs photoconductive semiconductor switch(PCSS) with an electrode distance of 4 mm. And made is an analysis of the switchs photovoltaic response characteristics under the high gain mode when the biased field is bigger than the Geng effect field. Also a theory is presented that the main reason for the photovoltaic pulse response delay is the transmission of charge domain, caused by the presence of EL2 energy level in the chip material. Finally, the transmission time of charge domain is calculated and a result that inosculates with the experiment is attained.
基金supported by the National Natural Science Foundation of China (Grant No.52109125)the Natural Science Foundation of Jiangsu Province,China (Grant No.BK20231217)the Key Laboratory of Geomechanics and Geotechnical Engineering Safety,Chinese Academy of Sciences (Grant No.SKLGME023001).
文摘The coupling effects of rainfall,earthquake,and complex topographic and geological conditions complicate the dynamic responses and disasters of slope-tunnel systems.For this,the large-scale shaking table tests were carried out to explore the dynamic responses of steep bedding slope-tunnel system under the coupling effect of rainfall and earthquake.Results show that the slope surface and elevation amplification effect exhibit pronounced nonlinear change caused by the tunnel and weak interlayers.When seismic wave propagates to tunnels,the weak interlayers and rock intersecting areas present complex wave field distribution characteristics.The dynamic responses of the slope are influenced by the frequency,amplitude,and direction of seismic waves.The acceleration amplification coefficient initially rises and then falls as increasing seismic frequency,peaking at 20 Hz.Additionally,the seismic damage process of slope is categorized into elastic(2-3 m/s^(2)),elastoplastic(4-5 m/s^(2))and plastic damage stages(≥6.5 m/s^(2)).In elastic stage,ΔMPGA(ratio of acceleration amplification factor)increases with increasing seismic intensity,without obvious strain distribution change.In plastic stage,ΔMPGA begins to gradually plummet,and the strain is mainly distributed in the damaged area.The modes of seismic damage in the slope-tunnel system are mainly of tensile failure of the weak interlayer,cracking failure of tunnel lining,formation of persistent cracks on the slope crest and waist,development and outward shearing of the sliding mass,and buckling failure at the slope foot under extrusion of the upper rock body.This study can serve as a reference for predicting the failure modes of tunnel-slope system in strong seismic regions.
文摘The phonotaxis of bushcrickets demonstrates that they have goodcapability of recognizing conspecific songs and locating the sound source,which bases on complicated auditory mechanisms of the central nervoussystem(CNS).This article describes the response characteristics of AN3,an auditory ascending neuron in the prothoracic ganglion,and its projec-tions within the brain.The AN3,with a quasi-tonic discharge pattern,has high sensitivity,directionality and ability to encode sound intensity.Therefore,it plays an important role in auditory information processingof CNS.Its projections in the brain are mainly concentrated in the lateralzone of the deutencephalon,where synaptically connecting local auditoryinterneurons in the brain.
基金This research was supported by the National Key Research Program of China(No.2018YFC0705202)National Natural Science Foundation of China(No.51638010).
文摘The liquid desiccant air-conditioning system is considered as an energy-efficient alternative to the vapor compression system.The dynamic response characteristics of the system under variable cooling load play an important role in the air temperature and humidity control performance of the system.However,the dynamic response characteristics have not been fully revealed in previous studies.Thus,a dynamic model for a heat pump driven liquid desiccant air-conditioning(HPLDAC)system is established to investigate the dynamic response characteristics of the system in this study.Subsequently,experiments were conducted to validate the accuracy of the dynamic model.The simulation results show a good agreement with the experimental data.The simulation results reveal that evaporating water from the solution is a time-consuming process,compared to adding water to the solution.It spends a long time for the HPLDAC system to decrease the high relative humidity of supply air to a low value,which limits the air temperature and humidity control performance of the system.The upper band for the water replenishing value opening(△φup)is a crucial parameter to improve the limitation.When△φup decreases from 1.0%产to 0.25%,the time consumed to reduce the supply air relative humidity to the new lower set value can be saved by 30.6%.
文摘We propose an electronic model in Spice, instead of traditional mathematical analysis, for analyzing the performance of ferroelectric liquid crystal （FLC） under various working conditions. Using this equivalent circuit model,it is easy to simulate and analyze the behavior of an FLC layer in three different typical parameters,including temperature, input light wavelength, and the frequency of driving voltage. We conclude that the response velocity drops as the wavelength increases in the range of visible light, and for the parameter of temperature, the velocity reaches its lowest value when the temperature reaches a certain degree,meanwhile,the frequency of driving voltage exerts important effects on the response velocity only when the frequency is beyond a critical value. Excellent agreement is achieved between simulation and experimental results.
基金supported by the National Natural Science Foundation of China (Grant No.52279116)the Key Projects of the Yalong River Joint Fund of the National Natural Science Foundation of China (Grant No.U1865203).
文摘Seismicity resulting from the near-or in-field fault activation significantly affects the stability of large-scale underground caverns that are operating under high-stress conditions.A comprehensive scientific assessment of the operational safety of such caverns requires an in-depth understanding of the response characteristics of the rock mass subjected to dynamic disturbances.To address this issue,we conducted true triaxial modeling tests and dynamic numerical simulations on large underground caverns to investigate the impact of static stress levels,dynamic load parameters,and input directions on the response characteristics of the surrounding rock mass.The findings reveal that:(1)When subjected to identical incident stress waves and static loads,the surrounding rock mass exhibits the greatest stress response during horizontal incidence.When the incident direction is fixed,the mechanical response is more pronounced at the cavern wall parallel to the direction of dynamic loading.(2)A high initial static stress level specifically enhances the impact of dynamic loading.(3)The response of the surrounding rock mass is directly linked to the amplitude of the incident stress wave.High amplitude results in tensile damage in regions experiencing tensile stress concentration under static loading and shear damage in regions experiencing compressive stress concentration.These results have significant implications for the evaluation and prevention of dynamic disasters in the surrounding rock of underground caverns experiencing dynamic disturbances.
基金National Natural Science Foundation of China, No.40901031 Shanghai Natural Science Foundation, No.09ZR1428800+3 种基金 National Key Project of Scientific and Technical Supporting Programs, No.2007BAC29B05 Special Project of Research-style Operation in Shanghai Meteorological Bureau, No.YJ200803 No.YJ200805 National 863 Program, No.2006AA12Z104
文摘Temporal and spatial response characteristics of vegetation NDVI to the variation of temperature and precipitation in the whole year, spring, summer and autumn was analyzed from April 1998 to March 2008 based on the SPOT VGT-NDVI data and daily temperature and precipitation data from 205 meteorological stations in eastern China. The results indicate that as a whole, the response of vegetation NDVI to the variation of temperature is more pronounced than that of precipitation in eastern China. Vegetation NDVI maximally responds to the variation of temperature with a lag of about 10 days, and it maximally responds to the variation of precipitation with a lag of about 30 days. The response of vegetation NDVI to temperature and precipitation is most pronounced in autumn, and has the longest lag in summer. Spatially, the maximum response of vegetation NDVI to the variation of temperature is more pronounced in the northern and middle parts than in the southern part of eastern China. The maximum response of vegetation NDVI to the variation of precipitation is more pronounced in the northern part than in the middle and southern parts of eastern China. The response of vegetation NDVI to the variation of temperature has longer lag in the northern and southern parts than in the middle part of eastern China. The response of vegetation NDVl to the variation of precipitation has the longest lag in the southern part, and the shortest lag in the northern part of eastern China. The response of vegetation NDVI to the variation of temperature and precipitation in eastern China is mainly consistent with other results, but the lag time of vegetation NDVI to the variation of temperature and precipitation has some differences with those results of the monsoon region of eastern China.
