This study provides a new experimental framework to measure the static and dynamic electrical parameters for a solar panel of multiple cells.The study evaluates its static parameters,including its resultant diodes’sa...This study provides a new experimental framework to measure the static and dynamic electrical parameters for a solar panel of multiple cells.The study evaluates its static parameters,including its resultant diodes’saturation currents,diodes’ideality factors,series,and shunt resistances.Such parameters are essential to characterise the steady-state performance of a solar panel.Additionally,the dynamic parameters as the equivalent junction and diffusion capacitances are also experimentally measured.These parameters impact the performance of the panel at variable solar irradiance,temperature,and load conditions.A solar panel of 36 series-connected cells has been utilised in this research to undertake this experimental evaluation.This work addresses a gap in the recent literature regarding a full evaluation of the internal electrical parameters in a whole solar panel of multiple cells.Firstly,a dark experimental environment has been developed so that no influence from external light sources can affect the measurements being taken.The panel is then stimulated with different types of electrical stresses in various circuit configurations to measure the required static and dynamic parameters.For the solar panel under study,the series and shunt resistances per cell have been evaluated to be 18.91 mΩand 5.6 kΩ,respectively,while the junction and diffusion capacitances have shown direct and inverse relationships,respectively,with the applied voltage as expected.The outcomes of these experimental setups highlighted the importance of the developed comprehensive framework in this research to be employed to assess the quality of the solar panel and its real-time performance at variable operational conditions.展开更多
The cyclic injection and production of fluids into and from underground gas storage(UGS)may lead to caprock failure,such as capillary sealing failure,hydraulic fracturing,shear failure,and fault slipping or dilation.T...The cyclic injection and production of fluids into and from underground gas storage(UGS)may lead to caprock failure,such as capillary sealing failure,hydraulic fracturing,shear failure,and fault slipping or dilation.The dynamic sealing capacity of a caprock-fault system is a critical constraint for safe operation,and is a key factor in determining the maximum operating pressure(MOP).This study proposed an efficient semi-analytical method for calculating changes in the in situ stress within the caprock.Next,the parameters of dynamic pore pressure,in situ stresses,and deformations obtained from reservoir simulations and geomechanical modeling were used for inputs for the analytical solution.Based on the calculated results,an experimental scheme for the coupled cyclic stress-permeability testing of caprock was designed.The stability analysis indicated that the caprock was not prone to fatigue shear failure under the current injection and production strategy,supported by the experimental results.The experimental results further reveal that the sealing capacity of caprock plugs may remain stable.This phenomenon is attributed to cyclic stress causing pore connectivity and microcrack initiation in certain plugs,while leading to pore compaction in others.A comparison between the dynamic pore pressure and the minimum principal stress suggests that the risk of tensile failure is extremely low.Furthermore,although the faults remain stable under the current injection and production strategies,the continuous increase in injection pressure may lead to an increased tendency for fault slip and dilation,which can cause fault slip ultimately.The MOPs corresponding to each failure mode were calculated.The minimum value of approximately 36.5 MPa at capillary sealing failure indicated that the gas breakthrough in the caprock occurred earlier than rock failure.Therefore,this minimumvalue can be used as the MOP for the target UGS.展开更多
In order to speed underwater launch of minor-caliber weapons,a sealing device can be set in front of underwater muzzle to separate water,preventing the muzzle from water immersion.By establishing and simplifying the m...In order to speed underwater launch of minor-caliber weapons,a sealing device can be set in front of underwater muzzle to separate water,preventing the muzzle from water immersion.By establishing and simplifying the model of underwater weapon sealing device and unstructured mesh computing domain model based on computational fluid dynamics（CFD）,dynamic mesh and user defined function（UDF）,the N-S equation is solved and the numerical analysis and calculation of the complex two-phase flow inside the sealing device are carried out.The results show that the gas discharged from the sealing device is conducive to the formation of the projectile supercavity.When the projectile is launched at 5munder water,the shock wave before and after the projectile has impact on the box body up to 100 MPa,therefore the sealing device must be strong enough.The research results have the vital significance to the design of underwater weapon sealing device and the formation of the projectile supercavitation.展开更多
In recent decades,control performance monitoring(CPM)has experienced remarkable progress in research and industrial applications.While CPM research has been investigated using various benchmarks,the historical data be...In recent decades,control performance monitoring(CPM)has experienced remarkable progress in research and industrial applications.While CPM research has been investigated using various benchmarks,the historical data benchmark(HIS)has garnered the most attention due to its practicality and effectiveness.However,existing CPM reviews usually focus on the theoretical benchmark,and there is a lack of an in-depth review that thoroughly explores HIS-based methods.In this article,a comprehensive overview of HIS-based CPM is provided.First,we provide a novel static-dynamic perspective on data-level manifestations of control performance underlying typical controller capacities including regulation and servo:static and dynamic properties.The static property portrays time-independent variability in system output,and the dynamic property describes temporal behavior driven by closed-loop feedback.Accordingly,existing HIS-based CPM approaches and their intrinsic motivations are classified and analyzed from these two perspectives.Specifically,two mainstream solutions for CPM methods are summarized,including static analysis and dynamic analysis,which match data-driven techniques with actual controlling behavior.Furthermore,this paper also points out various opportunities and challenges faced in CPM for modern industry and provides promising directions in the context of artificial intelligence for inspiring future research.展开更多
Static disorder plays a crucial role in the electronic dynamics and spec-troscopy of complex molecular sys-tems.Traditionally,obtaining ob-servables averaged over static disor-der requires thousands of realiza-tions v...Static disorder plays a crucial role in the electronic dynamics and spec-troscopy of complex molecular sys-tems.Traditionally,obtaining ob-servables averaged over static disor-der requires thousands of realiza-tions via direct sampling of the dis-order distribution,leading to high computational costs.In this work,we extend the auxiliary degree-of-freedom based matrix product state(MPS)method to handle system-bath correlated thermal equilibrium initial states,which can capture static disorder effects using a one-shot quantum dynamical simulation.We validate the effectiveness of the extended method by computing the dipole-dipole time correlation function of the Holstein model relevant to the emission spectrum of molecular aggregates.Our results show that the one-shot method is very accu-rate with only a moderate increase in MPS bond dimension,thereby significantly reducing computational cost.Moreover,it enables the generation of a much larger number of samples than the conventional direct sampling method at negligible additional cost,thus reducing sta-tistical errors.This method provides a broadly useful tool for calculating equilibrium time cor-relation functions in system-bath coupled models with static disorder.展开更多
The microstructure and related property evolution induced by dynamic recrystallization(DRX)and static recrystallization(SRX)in thermo-mechanical process are two critical factors for the metal forming.The DRX and SRX a...The microstructure and related property evolution induced by dynamic recrystallization(DRX)and static recrystallization(SRX)in thermo-mechanical process are two critical factors for the metal forming.The DRX and SRX are determined by the grain level deformation and sequentially coupled.In order to fully capture the microstructure and mechanical property evolution,a crystal plasticity finite element based modelling method for DRX and SRX is proposed in the current work.The grain level deformation is calculated with crystal plasticity which is coupled with the recrystallization model straightforwardly,and both the grain deformation and microstructure evolution are updated simultaneously.The proposed method is validated with discontinuous DRX experiments and the effects of initial deformation conditions are well-captured.Two controversial mechanisms for recrystallization microstructure evolution,i.e.oriented nucleation and growth selection,are discussed in the current framework with the advantages of accurate grain level deformation and interaction predictions.Furthermore,the sequentially coupled DRX and SRX are modelled seamlessly in the current work which provides a critical method for fully integrated thermo-mechanical processes analysis.展开更多
With the continuous development of deep oil and gas,minerals,geothermal resources,and other resources,there are increasingly more stringent requirements for equipment.In particular,the ultra-highpressure dynamic seals...With the continuous development of deep oil and gas,minerals,geothermal resources,and other resources,there are increasingly more stringent requirements for equipment.In particular,the ultra-highpressure dynamic seals of deep mining device need to be developed.Therefore,considering the use of dynamic seals in unique deep mining environments,an ultra-high-pressure rotating combined dynamic seal was designed and developed and its sealing performance was experimentally measured and analyzed.The results show that the experimental device can operate stably under a pressure of up to150 MPa and a rotating speed of 76 r/min,and can also operate normally under a rotating speed of up to 140 r/min and a sealing pressure of 120 MPa.During the operation of the ultra-high-pressure rotating combined dynamic seal,the sealing ring does not show obvious damage,which vouches for its sealing performance.No leakage of flow and pressure was detected in the all seal structures within the sealing pressure range of 0-150 MPa.Therefore,the dynamic sealing performance of the device is intact under ultra-high-pressure conditions and can be applied in deep mining environments at a certain depth.The research and development of this device can aid future deep energy exploration and exploitation.展开更多
The static sealing of underground gas storage(UGS),including the integrity of cap rocks and the stability of faults,is analyzed from a macro perspective using a comprehensive geological evaluation method.Changes in po...The static sealing of underground gas storage(UGS),including the integrity of cap rocks and the stability of faults,is analyzed from a macro perspective using a comprehensive geological evaluation method.Changes in pore structure,permeability,and mechanical strength of cap rocks under cyclic loads may impact the rock sealing integrity during the injection and recovery phases of UGS.In this work,the mechanical deformation and failure tests of rocks,as well as rock damage tests under alternating loads,are conducted to analyze the changes in the strength and permeability of rocks under multiple-cycle intense injection and recovery of UGS.Additionally,this study proposes an evaluation method for the dynamic sealing performance of UGS cap rocks under multi-cycle alternating loads.The findings suggest that the failure strength(70%)can be used as the critical value for rock failure,thus providing theoretical support for determining the upper limit of operating pressure and the number of injection-recovery cycles for the safe operation of a UGS system.展开更多
Less leakage is a benefit of parallel grooved liquid seals(labyrinth seals).But researches show that the liquid seal with parallel grooves on the rotor harms the rotor stability.The seal with helical grooves on stator...Less leakage is a benefit of parallel grooved liquid seals(labyrinth seals).But researches show that the liquid seal with parallel grooves on the rotor harms the rotor stability.The seal with helical grooves on stator performs well in terms of rotordynamics,and its leakage is sensitive to the rotating speed.To make use of the advantages of both seals and improve seal stability,based on the Smooth-stator/Parallel Grooved-rotor(SPG)liquid seal,a Helical Grooved-stator/Parallel Grooved-rotor(HGPG)liquid seal is designed.To evaluate two liquid seals'leakage,rotordynamic characteristics and drag power loss,a transient computational fluid dynamics-based method is employed.This method is based on the multi-frequency elliptical-orbit rotor whirling model and the mesh deformation technique.The published experimental data of the leakage and rotordynamic force coefficients for an SPG liquid seal are used to validate the accuracy and dependability of the current method.Seal leakage and force coefficients are presented and compared for the SPG liquid seal and the HGPG liquid seal at various pressure drops.The influences of parallel groove depth on the leakage and rotordynamic properties for the HGPG liquid seals at two rotational speeds(2000,6000 r/min)are analyzed.The numerical findings demonstrate that the novel HGPG liquid seal has a lower leakage flow rate(by$22.3%)than the traditional SPG liquid seal.There is an optimal parallel groove depth that minimizes leakage.The presented novel HGPG liquid seal significantly improves rotordynamic stability,due to the similar effective stiffness and the obviously larger positive effective damping.Reducing parallel groove depth can increase the positive effective damping.In terms of leakage and rotordynamic characteristics,the novel HGPG liquid seal is a better seal design for liquid turbomachinery.展开更多
The dynamic and static modulus of elasticity （MOE） between bluestained and non-bluestained lumber of Lodgepole pine were tested and analyzed by using three methods of Non-destructive testing （NDT）, Portable Ultras...The dynamic and static modulus of elasticity （MOE） between bluestained and non-bluestained lumber of Lodgepole pine were tested and analyzed by using three methods of Non-destructive testing （NDT）, Portable Ultrasonic Non-destructive Digital Indicating Testing （Pundit）, Metriguard and Fast Fourier Transform （FFT） and the normal bending method. Results showed that the dynamic and static MOE of bluestained wood were higher than those of non-bluestained wood. The significant differences in dynamic MOE and static MOE were found between bulestained and non-bluestained wood, of which, the difference in each of three dynamic MOE （Ep. the ultrasonic wave modulus of elasticity, Ems, the stress wave modulus of elasticity and El, the longitudinal wave modulus of elasticity） between bulestained and non-bluestained wood arrived at the 0.01 significance level, whereas that in the static MOE at the 0.05 significance level. The differences in MOE between bulestained and non-bluestained wood were induced by the variation between sapwood and heartwood and the different densities of bulestained and non-bluestained wood. The correlation between dynamic MOE and static MOE was statistically significant at the 0.01 significance level. Although the dynamic MOE values of Ep, Em, Er were significantly different, there exists a close relationship between them （arriving at the 0.01 correlation level）. Comparative analysis among the three techniques indicated that the accurateness of FFT was higher than that of Pundit and Metriguard. Effect of tree knots on MOE was also investigated. Result showed that the dynamic and static MOE gradually decreased with the increase of knot number, indicating that knot number had significant effect on MOE value.展开更多
Ecological reactive powder concrete (ECO-RPC) with small sized and differentvolume fraction steel fibers was prepared by substitution of ultra-fine industrial waste powder for50% to 60% cement by weight and replacemen...Ecological reactive powder concrete (ECO-RPC) with small sized and differentvolume fraction steel fibers was prepared by substitution of ultra-fine industrial waste powder for50% to 60% cement by weight and replacement of ground fine quartz sand with natural fine aggregate.The effect of steel fiber volume fraction and curing ages on the static mechanical behaviour ofECO-RPC was studied. Using the split Hopkinson pressure bar technique, the dynamic mechanicalbehaviour of ECO-RPC was investigated under different strain rates. The results show that the staticmechanical behaviour of ECO-RPC increases with the increase of steel fiber volume fraction andcuring ages. The type of ECO-RPC with the substitution of 25% ultra-fine slag, 25% ultra-fine flyash and 10% silica fume is better than the others with compressive strength, flexural strength, andfracture energy more than 200 MPa, 60 MPa and 30 kJ/m^2, respectively. ECO-RPC has excellent strainrate stiffening effects under dynamic load. Its peak stress, peak strain and the area understrain-stress curve increase with the increase of strain rate. Its fracture pattern changes frombrittleness to toughness under high strain rates.展开更多
The goal of this effort was to provide a static and dynamic collaborative optimization （CO） model for the design of ship hull structure. The CO model integrated with static, mode and dynamic analyses. In the system-...The goal of this effort was to provide a static and dynamic collaborative optimization （CO） model for the design of ship hull structure. The CO model integrated with static, mode and dynamic analyses. In the system-level optimization model, a new objective function was advised, integrating all the subsystem-levels＇ objective functions, so as to eliminate the effects of dimensions and magnitude order. The proposed CO architecture enabled multi-objectives of the system and subsystem-level to be considered at both levels during optimization. A bi-level optimization strategy was advised, using the multi-island genetic algorithm. The proposed model was demonstrated with a deck optimization problem of container ship stern. The analysis progress and results of example show that the CO strategy is not only feasible and reliable, but also well suited for use in actual optimization problems of ship design.展开更多
Based on Tess of the D'urbervilles and its two versions in Chinese, the static feature of English is clarifi ed from two aspects: preponderance of nouns and feeble verbs while the dynamic feature of Chinese is ref...Based on Tess of the D'urbervilles and its two versions in Chinese, the static feature of English is clarifi ed from two aspects: preponderance of nouns and feeble verbs while the dynamic feature of Chinese is refl ected by the frequent and fl exible application of verbs and verbal reduplication. The realistic value of this contrastive analysis is that it can point out the key points and diffi culties in learning English which is helpful for FL teaching, translation and lexicography.展开更多
The presence of geological structures such as faults, joints, and dykes has been observed near excavation boundaries in many rockburst case histories. In this paper, the role of discontinuities around tunnels in rockb...The presence of geological structures such as faults, joints, and dykes has been observed near excavation boundaries in many rockburst case histories. In this paper, the role of discontinuities around tunnels in rockburst occurrence was studied. For this purpose, the Abaqus explicit code was used to simulate dynamic rock failure in deep tunnels. Material heterogeneity was considered using Python scripting in Abaqus. Rockbursts near fault regions in deep tunnels under static and dynamic loads were studied.Several tunnel models with and without faults were built and static and dynamic loads were used to simulate rock failure. The velocity and the released kinetic energy of failed rocks, the failure zone around the tunnel, and the deformed mesh were studied to identify stable and unstable rock failures. Compared with models without discontinuities, the results showed that the velocity and the released kinetic energy of failed rocks were higher, the failure zone around the tunnel was larger, and the mesh was more deformed in the models with discontinuities, indicating that rock failure in the models with discontinuities was more violent. The modeling results confirm that the presence of geological structures in the vicinity of deep excavations could be one of the major influence factors for the occurrence of rockburst. It can explain localized rockburst occurrence in civil tunnels and mining drifts. The presented methodology in this paper for rockburst analysis can be useful for rockburst anticipation and control during mining and tunneling in highly stressed ground.展开更多
To investigate the bedding influence on coal mechanical behaviour in underground environments such as coal or rock burst, simulations of dynamic SHPB tests of pre-stressed coal specimens with different bedding angles ...To investigate the bedding influence on coal mechanical behaviour in underground environments such as coal or rock burst, simulations of dynamic SHPB tests of pre-stressed coal specimens with different bedding angles were carried out using a particle flow code 2-dimensional(PFC2D). Three impact velocities of 4, 8 and 12 m/s were selected to study dynamic behaviours of coal containing bedding planes under different dynamic loads. The simulation results showed that the existence of bedding planes leads to the degradation of the mechanical properties and their weakening effect significantly depends on the angle h between the bedding planes and load direction. With h increaseing from 0° to 90°, the strength first decreased and subsequently increased and specimens became most vulnerable when h was 30° or 45°.Five failure modes were observed in the specimens in the context of macro-cracks. Furthermore, energy characteristics combined with ultimate failure patterns revealed that maximum accumulated energy and failure intensity have a positive relation with the strength of specimen. When bedding planes were parallel or perpendicular to loading direction, specimens absorbed more energy and experienced more violent failure with increased number of cracks. In contrast, bedding planes with h of 30° or 45° reduced the specimens' ability of storing strain energy to the lowest with fewer cracks observed after failure.展开更多
The current research on secondary O-ring seals used in mechanical seals has begun to focus on their dynamic properties.However,detailed analysis of the dynamic properties of O-ring seals in spiral groove gas face seal...The current research on secondary O-ring seals used in mechanical seals has begun to focus on their dynamic properties.However,detailed analysis of the dynamic properties of O-ring seals in spiral groove gas face seals is lacking.In particular a transient study and a difference analysis of steady-state and transient performance are imperative.In this paper,a case study is performed to gauge the effect of secondary O-ring seals on the dynamic behavior(steady-state performance and transient performance)of face seals.A numerical finite element method(FEM)model is developed for the dynamic analysis of spiral groove gas face seals with a flexibly mounted stator in the axial and angular modes.The rotor tilt angle,static stator tilt angle and O-ring damping are selected to investigate the effect of O-ring seals on face seals during stable running operation.The results show that the angular factor can be ignored to save time in the simulation under small damping or undamped conditions.However,large O-ring damping has an enormous effect on the angular phase difference of mated rings,affecting the steady-state performance of face seals and largely increasing the possibility of face contact that reduces the service life of face seals.A pressure drop fluctuation is carried out to analyze the effect of O-ring seals on the transient performance of face seals.The results show that face seals could remain stable without support stiffness and O-ring damping during normal stable operation but may enter a large-leakage state when confronting instantaneous fluctuations.The oscillation-amplitude shortening effect of O-ring damping on the axial mode is much greater than that on the angular modes and O-ring damping prefers to cater for axial motion at the cost of angular motion.This research proposes a detailed dynamic-property study of O-ring seals in spiral groove gas face seals,to assist in the design of face seals.展开更多
The recrystallization behavior of a low carbon high niobium microalloyed steel was investigated using continuous and interrupted hot compression tests. The results showed that the initiation of dynamic recrystallizati...The recrystallization behavior of a low carbon high niobium microalloyed steel was investigated using continuous and interrupted hot compression tests. The results showed that the initiation of dynamic recrystallization （DRX） could be detected from inflection in the plot of the strain hardening rate against stress regardless of the stress peak appearance. According to the Zener-Hollomon parameter equation, the activity energy of DRX （Qad） was ob tained and a new modified expression calculating Qdef was proposed in consideration of the chemical composition of experimental steel. Applying the 2% offset method, the static softening fraction was determined. The graphic representation of the softening fraction vs interruption time gave the information about the non-static reerystallization temperature （about 1 000℃ ） and the relationship of precipitation time temperature. Static recrystallization kinetics followed the Avrami＇s law at high deformation temperature, and different values of the exponent m were given to illustrate the effect of niobium element on static recrystallization at different deformation temperatures.展开更多
The dry-gas seal has been widely used in different industries. With increased spin speed of the rotator shaft, turbulence occurs in the gas film between the stator and rotor seal faces. For the micro-scale flow in the...The dry-gas seal has been widely used in different industries. With increased spin speed of the rotator shaft, turbulence occurs in the gas film between the stator and rotor seal faces. For the micro-scale flow in the gas film and grooves, turbulence can change the pressure distribution of the gas film. Hence, the seal performance is influenced. However, turbulence effects and methods for their evaluation are not considered in the existing industrial designs of dry-gas seal. The present paper numerically obtains the turbulent flow fields of a spiral-groove dry-gas seal to analyze turbulence effects on seal performance. The direct numerical simulation （DNS） and Reynolds-averaged Navier-Stokes （RANS） methods are utilized to predict the velocity field properties in the grooves and gas film. The key performance parameter, open force, is obtained by integrating the pressure distribution, and the obtained result is in good agreement with the experimental data of other researchers. Very large velocity gradients are found in the sealing gas film because of the geometrical effects of the grooves. Considering turbulence effects, the calculation results show that both the gas film pressure and open force decrease. The RANS method underestimates the performance, compared with the DNS. The solution of the conventional Reynolds lubrication equation without turbulence effects suffers from significant calculation errors and a small application scope. The present study helps elucidate the physical mechanism of the hydrodynamic effects of grooves for improving and optimizing the industrial design or seal face pattern of a dry-gas seal.展开更多
Bulk flow model with perturbation simplification has been used to calculate rotordynamic coefficients in annular seals which have significant influences on the dynamic behavior of rotors in turbomachinery. In this wor...Bulk flow model with perturbation simplification has been used to calculate rotordynamic coefficients in annular seals which have significant influences on the dynamic behavior of rotors in turbomachinery. In this work, a transient bulk flow model with arbitrary rotor motion is developed, and the boundary conditions and friction factor in the model are calibrated with steady Computational Fluid Dynamics（CFD） analysis. The numerical solution scheme is developed based on the finite element method to obtain the transient reaction force in the seal clearance. With a periodic circular rotor orbit, the transient forces at multiple whirling frequencies are used to evaluate the rotordynamic coefficients. The leakage flowrate of CFD analysis has good agreement with experimental results and the calibrated parameters in bulk flow model are dependent on operating conditions. Although CFD calibration improves the accuracy of the perturbed bulk flow model, the direct damping is overestimated and the cross-coupled damping is underestimated. Compared with the perturbed model, the predictions of the transient bulk flow model are more agreeable with the experiment.展开更多
文摘This study provides a new experimental framework to measure the static and dynamic electrical parameters for a solar panel of multiple cells.The study evaluates its static parameters,including its resultant diodes’saturation currents,diodes’ideality factors,series,and shunt resistances.Such parameters are essential to characterise the steady-state performance of a solar panel.Additionally,the dynamic parameters as the equivalent junction and diffusion capacitances are also experimentally measured.These parameters impact the performance of the panel at variable solar irradiance,temperature,and load conditions.A solar panel of 36 series-connected cells has been utilised in this research to undertake this experimental evaluation.This work addresses a gap in the recent literature regarding a full evaluation of the internal electrical parameters in a whole solar panel of multiple cells.Firstly,a dark experimental environment has been developed so that no influence from external light sources can affect the measurements being taken.The panel is then stimulated with different types of electrical stresses in various circuit configurations to measure the required static and dynamic parameters.For the solar panel under study,the series and shunt resistances per cell have been evaluated to be 18.91 mΩand 5.6 kΩ,respectively,while the junction and diffusion capacitances have shown direct and inverse relationships,respectively,with the applied voltage as expected.The outcomes of these experimental setups highlighted the importance of the developed comprehensive framework in this research to be employed to assess the quality of the solar panel and its real-time performance at variable operational conditions.
基金supported by the National Natural Science Foundation of China(Grant No.42072166)Natural Science Foundation of Heilongjiang Province of China(Grant No.LH2020D004)Key R&D Program of Heilongjiang Province of China(Grant No.JD2023SJ26)。
文摘The cyclic injection and production of fluids into and from underground gas storage(UGS)may lead to caprock failure,such as capillary sealing failure,hydraulic fracturing,shear failure,and fault slipping or dilation.The dynamic sealing capacity of a caprock-fault system is a critical constraint for safe operation,and is a key factor in determining the maximum operating pressure(MOP).This study proposed an efficient semi-analytical method for calculating changes in the in situ stress within the caprock.Next,the parameters of dynamic pore pressure,in situ stresses,and deformations obtained from reservoir simulations and geomechanical modeling were used for inputs for the analytical solution.Based on the calculated results,an experimental scheme for the coupled cyclic stress-permeability testing of caprock was designed.The stability analysis indicated that the caprock was not prone to fatigue shear failure under the current injection and production strategy,supported by the experimental results.The experimental results further reveal that the sealing capacity of caprock plugs may remain stable.This phenomenon is attributed to cyclic stress causing pore connectivity and microcrack initiation in certain plugs,while leading to pore compaction in others.A comparison between the dynamic pore pressure and the minimum principal stress suggests that the risk of tensile failure is extremely low.Furthermore,although the faults remain stable under the current injection and production strategies,the continuous increase in injection pressure may lead to an increased tendency for fault slip and dilation,which can cause fault slip ultimately.The MOPs corresponding to each failure mode were calculated.The minimum value of approximately 36.5 MPa at capillary sealing failure indicated that the gas breakthrough in the caprock occurred earlier than rock failure.Therefore,this minimumvalue can be used as the MOP for the target UGS.
基金National Natural Science Foundation of China(No.51175481)
文摘In order to speed underwater launch of minor-caliber weapons,a sealing device can be set in front of underwater muzzle to separate water,preventing the muzzle from water immersion.By establishing and simplifying the model of underwater weapon sealing device and unstructured mesh computing domain model based on computational fluid dynamics（CFD）,dynamic mesh and user defined function（UDF）,the N-S equation is solved and the numerical analysis and calculation of the complex two-phase flow inside the sealing device are carried out.The results show that the gas discharged from the sealing device is conducive to the formation of the projectile supercavity.When the projectile is launched at 5munder water,the shock wave before and after the projectile has impact on the box body up to 100 MPa,therefore the sealing device must be strong enough.The research results have the vital significance to the design of underwater weapon sealing device and the formation of the projectile supercavitation.
基金supported in part by the National Natural Science Foundation of China(62125306)Zhejiang Key Research and Development Project(2024C01163)the State Key Laboratory of Industrial Control Technology,China(ICT2024A06)
文摘In recent decades,control performance monitoring(CPM)has experienced remarkable progress in research and industrial applications.While CPM research has been investigated using various benchmarks,the historical data benchmark(HIS)has garnered the most attention due to its practicality and effectiveness.However,existing CPM reviews usually focus on the theoretical benchmark,and there is a lack of an in-depth review that thoroughly explores HIS-based methods.In this article,a comprehensive overview of HIS-based CPM is provided.First,we provide a novel static-dynamic perspective on data-level manifestations of control performance underlying typical controller capacities including regulation and servo:static and dynamic properties.The static property portrays time-independent variability in system output,and the dynamic property describes temporal behavior driven by closed-loop feedback.Accordingly,existing HIS-based CPM approaches and their intrinsic motivations are classified and analyzed from these two perspectives.Specifically,two mainstream solutions for CPM methods are summarized,including static analysis and dynamic analysis,which match data-driven techniques with actual controlling behavior.Furthermore,this paper also points out various opportunities and challenges faced in CPM for modern industry and provides promising directions in the context of artificial intelligence for inspiring future research.
基金supported by the National Natural Science Foundation of China(No.22273005 and No.22422301)the Innovation Program for Quantum Science and Technology(No.2023ZD0300200)+1 种基金the National Security Academic Foundation(No.U2330201)the Fundamental Research Funds for the Central Universities.
文摘Static disorder plays a crucial role in the electronic dynamics and spec-troscopy of complex molecular sys-tems.Traditionally,obtaining ob-servables averaged over static disor-der requires thousands of realiza-tions via direct sampling of the dis-order distribution,leading to high computational costs.In this work,we extend the auxiliary degree-of-freedom based matrix product state(MPS)method to handle system-bath correlated thermal equilibrium initial states,which can capture static disorder effects using a one-shot quantum dynamical simulation.We validate the effectiveness of the extended method by computing the dipole-dipole time correlation function of the Holstein model relevant to the emission spectrum of molecular aggregates.Our results show that the one-shot method is very accu-rate with only a moderate increase in MPS bond dimension,thereby significantly reducing computational cost.Moreover,it enables the generation of a much larger number of samples than the conventional direct sampling method at negligible additional cost,thus reducing sta-tistical errors.This method provides a broadly useful tool for calculating equilibrium time cor-relation functions in system-bath coupled models with static disorder.
基金supported by the National Natural Science Foundation of China(Nos.52105384 and U2141215).
文摘The microstructure and related property evolution induced by dynamic recrystallization(DRX)and static recrystallization(SRX)in thermo-mechanical process are two critical factors for the metal forming.The DRX and SRX are determined by the grain level deformation and sequentially coupled.In order to fully capture the microstructure and mechanical property evolution,a crystal plasticity finite element based modelling method for DRX and SRX is proposed in the current work.The grain level deformation is calculated with crystal plasticity which is coupled with the recrystallization model straightforwardly,and both the grain deformation and microstructure evolution are updated simultaneously.The proposed method is validated with discontinuous DRX experiments and the effects of initial deformation conditions are well-captured.Two controversial mechanisms for recrystallization microstructure evolution,i.e.oriented nucleation and growth selection,are discussed in the current framework with the advantages of accurate grain level deformation and interaction predictions.Furthermore,the sequentially coupled DRX and SRX are modelled seamlessly in the current work which provides a critical method for fully integrated thermo-mechanical processes analysis.
基金supported by the Program for Guangdong Introducing Innovative and Enterpreneurial Teams(Grant No.2019ZT08G315)the National Natural Science Foundation of China(Grant No.51827901)
文摘With the continuous development of deep oil and gas,minerals,geothermal resources,and other resources,there are increasingly more stringent requirements for equipment.In particular,the ultra-highpressure dynamic seals of deep mining device need to be developed.Therefore,considering the use of dynamic seals in unique deep mining environments,an ultra-high-pressure rotating combined dynamic seal was designed and developed and its sealing performance was experimentally measured and analyzed.The results show that the experimental device can operate stably under a pressure of up to150 MPa and a rotating speed of 76 r/min,and can also operate normally under a rotating speed of up to 140 r/min and a sealing pressure of 120 MPa.During the operation of the ultra-high-pressure rotating combined dynamic seal,the sealing ring does not show obvious damage,which vouches for its sealing performance.No leakage of flow and pressure was detected in the all seal structures within the sealing pressure range of 0-150 MPa.Therefore,the dynamic sealing performance of the device is intact under ultra-high-pressure conditions and can be applied in deep mining environments at a certain depth.The research and development of this device can aid future deep energy exploration and exploitation.
文摘The static sealing of underground gas storage(UGS),including the integrity of cap rocks and the stability of faults,is analyzed from a macro perspective using a comprehensive geological evaluation method.Changes in pore structure,permeability,and mechanical strength of cap rocks under cyclic loads may impact the rock sealing integrity during the injection and recovery phases of UGS.In this work,the mechanical deformation and failure tests of rocks,as well as rock damage tests under alternating loads,are conducted to analyze the changes in the strength and permeability of rocks under multiple-cycle intense injection and recovery of UGS.Additionally,this study proposes an evaluation method for the dynamic sealing performance of UGS cap rocks under multi-cycle alternating loads.The findings suggest that the failure strength(70%)can be used as the critical value for rock failure,thus providing theoretical support for determining the upper limit of operating pressure and the number of injection-recovery cycles for the safe operation of a UGS system.
基金supported by the National Natural Science Foundation of China(Nos.52376029 and 52176042)。
文摘Less leakage is a benefit of parallel grooved liquid seals(labyrinth seals).But researches show that the liquid seal with parallel grooves on the rotor harms the rotor stability.The seal with helical grooves on stator performs well in terms of rotordynamics,and its leakage is sensitive to the rotating speed.To make use of the advantages of both seals and improve seal stability,based on the Smooth-stator/Parallel Grooved-rotor(SPG)liquid seal,a Helical Grooved-stator/Parallel Grooved-rotor(HGPG)liquid seal is designed.To evaluate two liquid seals'leakage,rotordynamic characteristics and drag power loss,a transient computational fluid dynamics-based method is employed.This method is based on the multi-frequency elliptical-orbit rotor whirling model and the mesh deformation technique.The published experimental data of the leakage and rotordynamic force coefficients for an SPG liquid seal are used to validate the accuracy and dependability of the current method.Seal leakage and force coefficients are presented and compared for the SPG liquid seal and the HGPG liquid seal at various pressure drops.The influences of parallel groove depth on the leakage and rotordynamic properties for the HGPG liquid seals at two rotational speeds(2000,6000 r/min)are analyzed.The numerical findings demonstrate that the novel HGPG liquid seal has a lower leakage flow rate(by$22.3%)than the traditional SPG liquid seal.There is an optimal parallel groove depth that minimizes leakage.The presented novel HGPG liquid seal significantly improves rotordynamic stability,due to the similar effective stiffness and the obviously larger positive effective damping.Reducing parallel groove depth can increase the positive effective damping.In terms of leakage and rotordynamic characteristics,the novel HGPG liquid seal is a better seal design for liquid turbomachinery.
基金This paper was supported by "Wood-inorganic Res-toration Material" in "Technique Introduction and Innovation of Bio-macromolecule New Material" of Introducing Overseas Advanced Forest Technology Innovation Program of China ("948" Innovation Pro-ject, Number: 2006-4-C03)
文摘The dynamic and static modulus of elasticity （MOE） between bluestained and non-bluestained lumber of Lodgepole pine were tested and analyzed by using three methods of Non-destructive testing （NDT）, Portable Ultrasonic Non-destructive Digital Indicating Testing （Pundit）, Metriguard and Fast Fourier Transform （FFT） and the normal bending method. Results showed that the dynamic and static MOE of bluestained wood were higher than those of non-bluestained wood. The significant differences in dynamic MOE and static MOE were found between bulestained and non-bluestained wood, of which, the difference in each of three dynamic MOE （Ep. the ultrasonic wave modulus of elasticity, Ems, the stress wave modulus of elasticity and El, the longitudinal wave modulus of elasticity） between bulestained and non-bluestained wood arrived at the 0.01 significance level, whereas that in the static MOE at the 0.05 significance level. The differences in MOE between bulestained and non-bluestained wood were induced by the variation between sapwood and heartwood and the different densities of bulestained and non-bluestained wood. The correlation between dynamic MOE and static MOE was statistically significant at the 0.01 significance level. Although the dynamic MOE values of Ep, Em, Er were significantly different, there exists a close relationship between them （arriving at the 0.01 correlation level）. Comparative analysis among the three techniques indicated that the accurateness of FFT was higher than that of Pundit and Metriguard. Effect of tree knots on MOE was also investigated. Result showed that the dynamic and static MOE gradually decreased with the increase of knot number, indicating that knot number had significant effect on MOE value.
文摘Ecological reactive powder concrete (ECO-RPC) with small sized and differentvolume fraction steel fibers was prepared by substitution of ultra-fine industrial waste powder for50% to 60% cement by weight and replacement of ground fine quartz sand with natural fine aggregate.The effect of steel fiber volume fraction and curing ages on the static mechanical behaviour ofECO-RPC was studied. Using the split Hopkinson pressure bar technique, the dynamic mechanicalbehaviour of ECO-RPC was investigated under different strain rates. The results show that the staticmechanical behaviour of ECO-RPC increases with the increase of steel fiber volume fraction andcuring ages. The type of ECO-RPC with the substitution of 25% ultra-fine slag, 25% ultra-fine flyash and 10% silica fume is better than the others with compressive strength, flexural strength, andfracture energy more than 200 MPa, 60 MPa and 30 kJ/m^2, respectively. ECO-RPC has excellent strainrate stiffening effects under dynamic load. Its peak stress, peak strain and the area understrain-stress curve increase with the increase of strain rate. Its fracture pattern changes frombrittleness to toughness under high strain rates.
基金Knowledge-based Ship-design Hyper-integrated Platform(KSHIP) of Ministry of Education and Ministry of Finance,P. R. China(No.200512)
文摘The goal of this effort was to provide a static and dynamic collaborative optimization （CO） model for the design of ship hull structure. The CO model integrated with static, mode and dynamic analyses. In the system-level optimization model, a new objective function was advised, integrating all the subsystem-levels＇ objective functions, so as to eliminate the effects of dimensions and magnitude order. The proposed CO architecture enabled multi-objectives of the system and subsystem-level to be considered at both levels during optimization. A bi-level optimization strategy was advised, using the multi-island genetic algorithm. The proposed model was demonstrated with a deck optimization problem of container ship stern. The analysis progress and results of example show that the CO strategy is not only feasible and reliable, but also well suited for use in actual optimization problems of ship design.
文摘Based on Tess of the D'urbervilles and its two versions in Chinese, the static feature of English is clarifi ed from two aspects: preponderance of nouns and feeble verbs while the dynamic feature of Chinese is refl ected by the frequent and fl exible application of verbs and verbal reduplication. The realistic value of this contrastive analysis is that it can point out the key points and diffi culties in learning English which is helpful for FL teaching, translation and lexicography.
基金Financial supports from the Natural Sciences and Engineering Research Council(NSERC)of Canada(CRDPJ 418932-11)Vale,LKAB,CEMI,MIRARCO,and the Open Research Fund of the State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(Grant No.Z015001)for this work are gratefully acknowledged
文摘The presence of geological structures such as faults, joints, and dykes has been observed near excavation boundaries in many rockburst case histories. In this paper, the role of discontinuities around tunnels in rockburst occurrence was studied. For this purpose, the Abaqus explicit code was used to simulate dynamic rock failure in deep tunnels. Material heterogeneity was considered using Python scripting in Abaqus. Rockbursts near fault regions in deep tunnels under static and dynamic loads were studied.Several tunnel models with and without faults were built and static and dynamic loads were used to simulate rock failure. The velocity and the released kinetic energy of failed rocks, the failure zone around the tunnel, and the deformed mesh were studied to identify stable and unstable rock failures. Compared with models without discontinuities, the results showed that the velocity and the released kinetic energy of failed rocks were higher, the failure zone around the tunnel was larger, and the mesh was more deformed in the models with discontinuities, indicating that rock failure in the models with discontinuities was more violent. The modeling results confirm that the presence of geological structures in the vicinity of deep excavations could be one of the major influence factors for the occurrence of rockburst. It can explain localized rockburst occurrence in civil tunnels and mining drifts. The presented methodology in this paper for rockburst analysis can be useful for rockburst anticipation and control during mining and tunneling in highly stressed ground.
基金the Chinese Scholarship Council (No. 201706370022) for the financial support to the joint Ph.D. programme at the University of Wollongong,Australia
文摘To investigate the bedding influence on coal mechanical behaviour in underground environments such as coal or rock burst, simulations of dynamic SHPB tests of pre-stressed coal specimens with different bedding angles were carried out using a particle flow code 2-dimensional(PFC2D). Three impact velocities of 4, 8 and 12 m/s were selected to study dynamic behaviours of coal containing bedding planes under different dynamic loads. The simulation results showed that the existence of bedding planes leads to the degradation of the mechanical properties and their weakening effect significantly depends on the angle h between the bedding planes and load direction. With h increaseing from 0° to 90°, the strength first decreased and subsequently increased and specimens became most vulnerable when h was 30° or 45°.Five failure modes were observed in the specimens in the context of macro-cracks. Furthermore, energy characteristics combined with ultimate failure patterns revealed that maximum accumulated energy and failure intensity have a positive relation with the strength of specimen. When bedding planes were parallel or perpendicular to loading direction, specimens absorbed more energy and experienced more violent failure with increased number of cracks. In contrast, bedding planes with h of 30° or 45° reduced the specimens' ability of storing strain energy to the lowest with fewer cracks observed after failure.
基金Supported by National Key Basic Research Program of China(973Program,Grant No.2012CB026003)National Science and Technology Major Project of China(Grant No.ZX06901)
文摘The current research on secondary O-ring seals used in mechanical seals has begun to focus on their dynamic properties.However,detailed analysis of the dynamic properties of O-ring seals in spiral groove gas face seals is lacking.In particular a transient study and a difference analysis of steady-state and transient performance are imperative.In this paper,a case study is performed to gauge the effect of secondary O-ring seals on the dynamic behavior(steady-state performance and transient performance)of face seals.A numerical finite element method(FEM)model is developed for the dynamic analysis of spiral groove gas face seals with a flexibly mounted stator in the axial and angular modes.The rotor tilt angle,static stator tilt angle and O-ring damping are selected to investigate the effect of O-ring seals on face seals during stable running operation.The results show that the angular factor can be ignored to save time in the simulation under small damping or undamped conditions.However,large O-ring damping has an enormous effect on the angular phase difference of mated rings,affecting the steady-state performance of face seals and largely increasing the possibility of face contact that reduces the service life of face seals.A pressure drop fluctuation is carried out to analyze the effect of O-ring seals on the transient performance of face seals.The results show that face seals could remain stable without support stiffness and O-ring damping during normal stable operation but may enter a large-leakage state when confronting instantaneous fluctuations.The oscillation-amplitude shortening effect of O-ring damping on the axial mode is much greater than that on the angular modes and O-ring damping prefers to cater for axial motion at the cost of angular motion.This research proposes a detailed dynamic-property study of O-ring seals in spiral groove gas face seals,to assist in the design of face seals.
基金Item Sponsored by National Natural Science Foundation of China(51074052)Fundamental Research Funds for Central Universities of China(N100607001)
文摘The recrystallization behavior of a low carbon high niobium microalloyed steel was investigated using continuous and interrupted hot compression tests. The results showed that the initiation of dynamic recrystallization （DRX） could be detected from inflection in the plot of the strain hardening rate against stress regardless of the stress peak appearance. According to the Zener-Hollomon parameter equation, the activity energy of DRX （Qad） was ob tained and a new modified expression calculating Qdef was proposed in consideration of the chemical composition of experimental steel. Applying the 2% offset method, the static softening fraction was determined. The graphic representation of the softening fraction vs interruption time gave the information about the non-static reerystallization temperature （about 1 000℃ ） and the relationship of precipitation time temperature. Static recrystallization kinetics followed the Avrami＇s law at high deformation temperature, and different values of the exponent m were given to illustrate the effect of niobium element on static recrystallization at different deformation temperatures.
基金supported by Scientific Research Foundation for Returned Scholars,Ministry of Education of China
文摘The dry-gas seal has been widely used in different industries. With increased spin speed of the rotator shaft, turbulence occurs in the gas film between the stator and rotor seal faces. For the micro-scale flow in the gas film and grooves, turbulence can change the pressure distribution of the gas film. Hence, the seal performance is influenced. However, turbulence effects and methods for their evaluation are not considered in the existing industrial designs of dry-gas seal. The present paper numerically obtains the turbulent flow fields of a spiral-groove dry-gas seal to analyze turbulence effects on seal performance. The direct numerical simulation （DNS） and Reynolds-averaged Navier-Stokes （RANS） methods are utilized to predict the velocity field properties in the grooves and gas film. The key performance parameter, open force, is obtained by integrating the pressure distribution, and the obtained result is in good agreement with the experimental data of other researchers. Very large velocity gradients are found in the sealing gas film because of the geometrical effects of the grooves. Considering turbulence effects, the calculation results show that both the gas film pressure and open force decrease. The RANS method underestimates the performance, compared with the DNS. The solution of the conventional Reynolds lubrication equation without turbulence effects suffers from significant calculation errors and a small application scope. The present study helps elucidate the physical mechanism of the hydrodynamic effects of grooves for improving and optimizing the industrial design or seal face pattern of a dry-gas seal.
基金supported by the National Natural Science Foundation of China(No.11176010)
文摘Bulk flow model with perturbation simplification has been used to calculate rotordynamic coefficients in annular seals which have significant influences on the dynamic behavior of rotors in turbomachinery. In this work, a transient bulk flow model with arbitrary rotor motion is developed, and the boundary conditions and friction factor in the model are calibrated with steady Computational Fluid Dynamics（CFD） analysis. The numerical solution scheme is developed based on the finite element method to obtain the transient reaction force in the seal clearance. With a periodic circular rotor orbit, the transient forces at multiple whirling frequencies are used to evaluate the rotordynamic coefficients. The leakage flowrate of CFD analysis has good agreement with experimental results and the calibrated parameters in bulk flow model are dependent on operating conditions. Although CFD calibration improves the accuracy of the perturbed bulk flow model, the direct damping is overestimated and the cross-coupled damping is underestimated. Compared with the perturbed model, the predictions of the transient bulk flow model are more agreeable with the experiment.
