Objective The use of lasers has been an important part of urology in the treatment of stone and prostate disease.The thermal effects of lasers in lithotripsy have been a subject of debate over the years.The objective ...Objective The use of lasers has been an important part of urology in the treatment of stone and prostate disease.The thermal effects of lasers in lithotripsy have been a subject of debate over the years.The objective of this review was to assess the current state of knowledge available on the thermal effects of lasers in lithotripsy,as well as explore any new areas where studies are needed.Methods In August 2022,a keyword search on Google Scholar,PubMed,and Scopus for all papers containing the phrases“thermal effects”AND“laser”AND“lithotripsy”AND“urology”was done followed by citation jumping to other studies pertaining to the topic and 35 relevant papers were included in our study.The data from relevant papers were segregated into five groups according to the factor studied and type of study,and tables were created for a comparison of data.Results Temperature above the threshold of 43℃ was reached only when the power was>40 W and when there was adequate irrigation(at least 15–30 mL/min).Shorter lasing time divided by lithotripsy time or operator duty cycles less than 70%also resulted in a smaller temperature rise.Conclusion At least eight factors modify the thermal effects of lasers,and most importantly,the use of chilled irrigation at higher perfusion rates,lower power settings of<40 W,and with a shorter operator duty cycle will help to prevent thermal injuries from occurring.Stones impacted in the ureter or pelvi-ureteric junction further increase the probability of thermal injuries during laser firing.展开更多
The stimulation of shale reservoirs frequently involves significant shear failure,which is crucial for creating fracture networks and enhancing permeability to boost production.As the depth of extraction increases,the...The stimulation of shale reservoirs frequently involves significant shear failure,which is crucial for creating fracture networks and enhancing permeability to boost production.As the depth of extraction increases,the impact of elevated temperatures on the anisotropic shear strength and failure mechanisms of shale becomes pronounced,yet there is a notable lack of relevant research.This study conducts,for the first time,direct shear experiment on shales at four different temperatures and seven bedding angles.By employing acoustic emission(AE)and digital image correlation(DIC)techniques,the evolution of damage and the mechanism of crack propagation under anisotropic direct shearing at varying temperatures is revealed.The results indicate that both shear displacement and strength of shale increase with temperature across different bedding angles.Additionally,shale demonstrates distinct brittle failure characteristics under various conditions during direct shearing tests.The types of anisotropic shear failure observed under the influence of temperature include central shearing fracture,central shearing with secondary fracture,and deflected slip along the bedding.Moreover,the temperature effect enhances shear-induced crack propagation along bedding planes.Shear failure in shale predominantly occurs during higher loading stages,which coincide with a substantial amount of AE signals.Finally,the introduction of the anisotropy index and temperature sensitivity coefficient further elucidates the interaction mechanism between thermal effects and anisotropy.This study offers a novel methodology to explore the anisotropic shear failure behavior of shale under elevated temperatures,and also provides crucial theoretical and experimental insights into shear failure behavior relevant to practical shale reservoir stimulation.展开更多
The exploitation of organic-inorganic hybrid perovskites(OIHPs) as active layer materials for typical sandwich-structured resistive memories has attracted widespread interest due to the property of low power consumpti...The exploitation of organic-inorganic hybrid perovskites(OIHPs) as active layer materials for typical sandwich-structured resistive memories has attracted widespread interest due to the property of low power consumption and fast switching. However, the inherent thermal instability of perovskites limits the application of OIHPs-based resistive memories under extreme conditions, while the infiuence of thermal effects on their resistance change characteristics remains unclear. Herein, a novel 2D <100>-oriented high-temperature resistant OIHP [(BIZ-H)_(2)(PbBr_(4))]n(BIZ = benzimidazole) is prepared as an active layer material to fabricate FTO/[(BIZ-H)_(2)(PbBr_(4))]n/Ag resistive memory with excellent thermal reproducibility and stability up to 120℃. The increase in temperature leads to a decrease in the PbBr_(6) octahedral distortion in the crystal structure, an increase in hydrogen bonding between the(BIZ-H)+cation and the(PbBr_(4))_(n)^(2n-)layer, and a shortening of the spacing of the inorganic layers, which is found to result in the creation and predominance of thermally activated traps with increasing temperature. This work provides a new direction for the next generation of OIHPs-based resistive memories with high-temperature tolerance.展开更多
The monument thermal effect(MTE)displacements could result in periodical signals with several mil-limeters magnitudes in the vertical and horizontal GPS position time series.However,the interaction ofvarious origins o...The monument thermal effect(MTE)displacements could result in periodical signals with several mil-limeters magnitudes in the vertical and horizontal GPS position time series.However,the interaction ofvarious origins of periodic signals in GPS observations makes it difficult to isolate the millimeter-levelMTE displacement from other signals and noises.In this study,to assess the diurnal and semidiurnalsignals induced by MTE,we processed 12 very short GPS baselines(VSGB)with length<150 m.Themonument pairs for each baseline differ in their heights,horizontal structure,or base foundations.Meanwhile,two zero-baselines were also processed as the control group.Results showed that the sea-sonal signals observed in VSGB time series in the horizontal and vertical directions,were mainly inducedby seasonal MTE.Time-varying diurnal and semidiurnal signals with amplitude up to 4 mm wereobserved in the vertical direction for baselines with monument height difference(MHD)larger than10 m.Horizontal diurnal signal with an amplitude of about 2 mm was also detected for baselines withnon-axisymmetric monument structure.The orientation of the detected horizontal displacement wascoherent with the direction of daily temperature variation(DTV)driven by direct solar radiation,whichindicates that the diurnal and semidiurnal signals are likely induced by MTE.The observed high-frequency MTE displacements,if not well modeled and removed,may propagate into spurious long-term signals and bias the velocity estimation in the daily GPS time series.展开更多
Dielectric barrier discharge(DBD)plasma excited by a high-frequency alternating-current(AC)power supply is widely employed for the degradation of volatile organic compounds(VOCs).However,the thermal effect generated d...Dielectric barrier discharge(DBD)plasma excited by a high-frequency alternating-current(AC)power supply is widely employed for the degradation of volatile organic compounds(VOCs).However,the thermal effect generated during the discharge process leads to energy waste and low energy utilization efficiency.In this work,an innovative DBD thermally-conducted catalysis(DBD-TCC)system,integrating high-frequency AC-DBD plasma and its generated thermal effects to activate the Co/SBA-15 catalyst,was employed for toluene removal.Specifically,Co/SBA-15 catalysts are closely positioned to the ground electrode of the plasma zone and can be heated and activated by the thermal effect when the voltage exceeds 10 k V.At12.4 k V,the temperature in the catalyst zone reached 261℃ in the DBD-TCC system,resulting in an increase in toluene degradation efficiency of 17%,CO_(2)selectivity of 21.2%,and energy efficiency of 27%,respectively,compared to the DBD system alone.In contrast,the DBD thermally-unconducted catalysis(DBD-TUC)system fails to enhance toluene degradation due to insufficient heat absorption and catalytic activation,highlighting the crucial role of AC-DBD generated heat in the activation of the catalyst.Furthermore,the degradation pathway and mechanism of toluene in the DBD-TCC system were hypothesized.This work is expected to provide an energy-efficient approach for high-frequency AC-DBD plasma removal of VOCs.展开更多
Molecular dynamics （MD） simulations of monocrystalline copper （100） surface during nanomachining process were performed based on a new 3D simulation model. The material removal mechanism and system temperature dis...Molecular dynamics （MD） simulations of monocrystalline copper （100） surface during nanomachining process were performed based on a new 3D simulation model. The material removal mechanism and system temperature distribution were discussed. The simulation results indicate that the system temperature distribution presents a roughly concentric shape, a steep temperature gradient is observed in diamond cutting tool, and the highest temperature is located in chip. Centrosymmetry parameter method was used to monitor defect structures. Dislocations and vacancies are the two principal types of defect structures. Residual defect structures impose a major change on the workpiece physical properties and machined surface quality. The defect structures in workpiece are temperature dependent. As the temperature increases, the dislocations are mainly mediated from the workpiece surface, while the others are dissociated into point defects. The relatively high cutting speed used in nanomachining results in less defect structures, beneficial to obtain highly machined surface quality.展开更多
A DC to 5GHz series MEMS switch is designed and fabricated for wireless communication applications,and thermal effect and power handling of the series switch are discussed.The switch is made on glass substrate,and gol...A DC to 5GHz series MEMS switch is designed and fabricated for wireless communication applications,and thermal effect and power handling of the series switch are discussed.The switch is made on glass substrate,and gold platinum contact is used to get a stable and little insert loss.From DC to 5GHz,0 6dB insertion loss,30dB isolation,and 30μs delay are demonstrated.Thermal effect of the switch is tested in 85℃ and -55℃ atmosphere separately.From DC to 4GHz,the insert loss of the switch increases 0 2dB in 85℃ and 0 4dB in -55℃,while the isolation holds the same value as that in room temperature.To measure the power handling capability of the switch,we applied a continuous RF power increasing from 10dBm to 35 1dBm with the step of 1 0dBm across the switch at 4GHz.The switch keeps working and shows a decrease of the insert loss for 0 1～0 6dB.The maximum continuous power handling (35 1dBm,about 3 24W) is higer than the reported value of shunt switch (about 420mW),which implies series switches have much better power handling capability.展开更多
The objective of this paper is to investigate the effect of water temperature on cavitation characteristics in a turbopump inducer,a series of experiments at different temperatures have been conducted in a newly devel...The objective of this paper is to investigate the effect of water temperature on cavitation characteristics in a turbopump inducer,a series of experiments at different temperatures have been conducted in a newly developed visualization test facility.It is found that higher temperature shows little influence on the non-cavitation performance and breakdown characteristic in the investigated range.The relationship between cavitation development and pressure fluctuation has been discussed in detail.Higher temperature displays a remarkable stabilization effect on the cavitation excited pressure.In particular,the inception cavitation numbers of both the super-synchronous rotating cavitation and synchronous rotating cavitation are decreased at higher temperatures,and the corresponding frequencies are not affected,while the amplitudes are distinctly reduced,and the occurrence range of synchronous rotating cavitation is significantly narrowed.A generalized RayleighPlesset equation has been employed to account for the thermal effect on the bubble development,which may provide a deep insight in understanding the experimental results.Thermal effect is found to act as a remarkable dissipation mechanism to suppress the bubble growth,smooth the collapse.In particular,the excited pressure during collapse is smaller at higher temperatures,which may lead to the stabilization effect of high temperature in this study.展开更多
A thermal hydraulic model based on the lumped parameter method is presented to analyze the load-carrying capacity of a slipper pair in an aviation axial-piston pump under specified operating conditions. Both theoretic...A thermal hydraulic model based on the lumped parameter method is presented to analyze the load-carrying capacity of a slipper pair in an aviation axial-piston pump under specified operating conditions. Both theoretical and experimental results are presented to demonstrate the validity of the thermal hydraulic model. The results illustrate that the squeezing force and thermal wedge bearing force are the main factors that affect the film thickness and load-carrying capacity.At high oil temperature and high load pressure, the film thickness decreases with increasing clamping force due to a combined action of the squeezing bearing force and the thermal wedge bearing force, but the load-carrying capacity will increase. An increase of the film thickness is proven to be beneficial under high shaft rotational speed but especially dangerous as it strongly increases the ripple amplitude of the film thickness, which leads to decreasing the load-carrying capacity. The structural parameters of the slipper can be optimized to achieve desired performance, such as the slipper radius ratio and orifice length diameter ratio. To satisfy the requirement of the load-carrying capacity, the slipper radius ratio should be selected from 1.4 to 1.8, and the orifice length diameter ratio should be selected from 4 to 5.展开更多
A key design issue related to the turbopump of the rocket engine is that cavitation occurs in cryogenic fluids when the fluid pressure is lower than the vapor pressure at a local thermodynamic state. Cavitation in cry...A key design issue related to the turbopump of the rocket engine is that cavitation occurs in cryogenic fluids when the fluid pressure is lower than the vapor pressure at a local thermodynamic state. Cavitation in cryogenic fluids generates substantial thermal effects and strong variations in fluid properties, which in turn alter the cavity characteristics. To date, fewer investigate the thermal effect on cavitation in cryogenic fluids clearly by the numerical methods due to the difficulty of the heat transfer in the phase change process. In order to study the thermal effect on cavitation in cryogenic fluid, computations are conducted around a 2D quarter caliber hydrofoil in liquid nitrogen and hydrogen respectively by implementing modified Merkle cavitation model, which accounts for the energy balance and variable thermodynamic properties of the fluid. The numerical results show that with the thermal effect, the vapour content in constant location decreases, the cavity becomes more porous and the interface becomes less distinct which shows increased spreading while getting shorter in length. In the cavity region, the temperature around the cavity depresses due to absorb the evaporation latent heat and the saturation pressure drops. When the vapour volume fraction is higher, the temperature depression and pressure depression becomes larger. It is also observed that a slight temperature rise is found above the reference fluid temperature at the cavity rear end attributed to the release of latent heat during the condensation process. When the fluid is operating close to its critical temperature, thermal effects on cavitation are more obviously in both the liquid nitrogen and hydrogen. The thermal effect on cavitation in liquid hydrogen is more distinctly compared with that in liquid nitrogen due to the density ratio, vapour pressure and other variable properties of the fluid. The investigation provides aid for the design of the cryogenic pump of the liquid rocket.展开更多
This paper reports the modeling method and outcomes of mechanical performance and damage evolution of single-lap bolted composite interference-fit joints under extreme temperatures.The anisotropic continuum damage mod...This paper reports the modeling method and outcomes of mechanical performance and damage evolution of single-lap bolted composite interference-fit joints under extreme temperatures.The anisotropic continuum damage model involving thermal effects is established on continuum damage mechanics which integrates the shear nonlinearity constitutive relations characterized by Romberg-Osgood equation.The temperature-induced modification of thermal strains and material properties is incorporated in stress-strain analysis,extended 3 D failure criteria and exponential damage evolution rules.The proposed model is calibrated and employed to simulate behavior of composite joints in interference fitting,bolt preloading,thermal and bearing loading processes,during which the influence of interference-fit sizes,preload levels,laminate layups and service temperatures is thoroughly investigated.The predicated interfacial behavior,bearing response and failure modes are in good agreement with experimental tests.The numerical model is even capable of reflecting some non-intuitive experimental findings such as residual stress relaxation and matrix softening at elevated temperatures.展开更多
This paper studies the thermal effect of the cable-stayed bridge tower based on full time accurate measurement and finite element analysis on Xiantao Hanjiang River Highway Bridge. The measured results and the displac...This paper studies the thermal effect of the cable-stayed bridge tower based on full time accurate measurement and finite element analysis on Xiantao Hanjiang River Highway Bridge. The measured results and the displacement variation of top tower show that the tower rotates periodically when it is exposed in sunshine. But the tower column will not decline when there is no sunshine. In spite of in winter or in summer, the period when the tower column changed smallest is from 0∶00 am to 5∶00 am. The time period when the tower column has maximum deviation lags behind the time when the tower column has maximum temperature difference, and this phenomenon is obvious in winter. The conclusions also have directive value in predicting the tower deformations and their directions in construction control of cable-stayed bridge, and in verifying the finite element program.展开更多
In this study, we examined the thermal effects throughout the process of the placement of span-scale girder segments on a 6×110-m continuous steel box girder in the Hong Kong-Zhuhai-Macao Bridge. Firstly, when a ...In this study, we examined the thermal effects throughout the process of the placement of span-scale girder segments on a 6×110-m continuous steel box girder in the Hong Kong-Zhuhai-Macao Bridge. Firstly, when a span-scale girder segment is temporarily stored in the open air, temperature gradients will significantly increase the maximum reaction force on temporary supports and cause local buckling at the bottom of the girder segment. Secondly, due to the temperature difference of the girder segments before and after girth-welding, some residual thermal deflections will appear on the girder segments because the boundary conditions of the structure are changed by the girth-welding. Thirdly, the thermal expansion and thermal bending of girder segments will cause movement and rotation of bearings, which must be considered in setting bearings. We propose control measures for these problems based on finite element method simulation with field-measured temperatures. The local buckling during open-air storage can be avoided by reasonably determining the appropriate positions of temporary supports using analysis of overall and local stresses. The residual thermal deflections can be overcome by performing girth-welding during a period when the vertical temperature difference of the girder is within 1 °C, such as after 22:00. Some formulas are proposed to determine the pre-set distances for bearings, in which the movement and rotation of the bearings due to dead loads and thermal loads are considered. Finally, the feasibility of these control measures in the placement of span-scale girder segments on a real continuous girder was verified: no local buckling was observed during open-air storage;the residual thermal deflections after girth-welding were controlled within 5 mm and the residual pre-set distances of bearings when the whole continuous girder reached its design state were controlled within 20 mm.展开更多
We maintained gravid Chinese skinks(Plestiodon chinensis) at three constant temperatures(25, 28 and 31 °C) during gestation, and randomly assigned eggs from each female to one of the same three temperatures for i...We maintained gravid Chinese skinks(Plestiodon chinensis) at three constant temperatures(25, 28 and 31 °C) during gestation, and randomly assigned eggs from each female to one of the same three temperatures for incubation to determine maternal thermal effects on female reproduction and hatchling phenotype. Maternal temperature affected egg-laying date, hatching success and hatchling linear size(snout-vent length, SVL) but not clutch size, egg size, egg component, and embryonic stage at laying. More specifically, females at higher temperatures laid eggs earlier than did those at low temperatures, eggs laid at 31 °C were less likely to hatch than those laid at 25 °C or 28 °C, and hatchlings from eggs laid at 31 °C were smaller in SVL. Our finding that maternal temperature(pre-ovipositional thermal condition) rather than incubation temperature(post-ovipositional thermal condition) affected hatching success indicated that embryos at early stages were more vulnerable to temperature than those at late stages. Our data provide an inference that moderate maternal temperatures enhance reproductive fitness in P. chinensis.展开更多
Three-dimensional（3D） crossbar array architecture is one of the leading candidates for future ultra-high density nonvolatile memory applications. To realize the technological potential, understanding the reliability...Three-dimensional（3D） crossbar array architecture is one of the leading candidates for future ultra-high density nonvolatile memory applications. To realize the technological potential, understanding the reliability mechanisms of the3 D RRAM array has become a field of intense research. In this work, the endurance performance of the 3D 1D1 R crossbar array under the thermal effect is investigated in terms of numerical simulation. It is revealed that the endurance performance of the 3D 1D1 R array would be seriously deteriorated under thermal effects as the feature size scales down to a relatively small value. A possible method to alleviate the thermal effects is provided and verified by numerical simulation.展开更多
This study examined the thermal effects of building′s external wall surfaces, using observational data of spatial-temporal distribution of surface temperature, air temperature, and heat flux into and out of external ...This study examined the thermal effects of building′s external wall surfaces, using observational data of spatial-temporal distribution of surface temperature, air temperature, and heat flux into and out of external surface. Results indicate that external wall surface temperature and nearby air temperature vary with the change of orientation, height and season. In general, the external wall surface temperature is lower near the ground, and is higher near the roof, than nearby air temperature. But north wall surface temperature is mostly lower than nearby air temperature at the same height; south wall surface temperature during the daytime in December, and west wall surface temperature all day in August, is respectively higher than nearby air temperature. The heat fluxes into and out of external wall surfaces show the differences that exist in the various orientations, heights and seasons. In December, south wall surface at the lower sites emits heat and north wall surface at the higher sites absorbs heat. In April, all external wall surfaces, emit heat near the ground and absorb heat near the roof. In August, west wall surface all day emits heat, and other wall surfaces just show the commensurate behavior with that in April.展开更多
Thermal effects on the Callovo-Oxfordian and Opalinus clay rocks for hosting high-level radioactive waste were comprehensively investigated with laboratory and in situ experiments under repository relevant conditions:...Thermal effects on the Callovo-Oxfordian and Opalinus clay rocks for hosting high-level radioactive waste were comprehensively investigated with laboratory and in situ experiments under repository relevant conditions:(1) stresses covering the range from the initial lithostatic state to redistributed levels after excavation,(2) hydraulic drained and undrained boundaries, and(3) heating from ambient temperature up to 90℃-120℃ and a subsequent cooling phase. The laboratory experiments were performed on normal-sized and large hollow cylindrical samples in various respects of thermal expansion and contraction, thermally-induced pore water pressure, temperature influences on deformation and strength, thermal impacts on swelling, fracture sealing and permeability. The laboratory results obtained from the samples are consistent with the in situ observations during heating experiments in the underground research laboratories at Bure and Mont-Terri. Even though the claystones showed significant responses to thermal loading, no negative effects on their favorable barrier properties were observed.展开更多
The dynamic performance of composite flexible multi-body system under the simultaneous action of thermal fields and driving constraint is analyzed. Based on strain-displacement relation of the Mindlin plate theory whi...The dynamic performance of composite flexible multi-body system under the simultaneous action of thermal fields and driving constraint is analyzed. Based on strain-displacement relation of the Mindlin plate theory which includes transverse shear deformation, and considering thermal effect, variation equations of laminated plate are derived by the principle of virtual work. The finite element method is used for discretization. According to kinematics constraint relation, dynamic equations for spatial slider-crank system are established. Simulation results show that spatial deformation （torsion deformation） appears in the multi-layered composite slider-crank mechanism which is simulated with planar motions. Furthermore, the influence of coupling between thermal expansion and flexible deformations of non-symmetrical composite plates on the large overall motion under the uniform temperature field is investigated. Finally, significant change in constraint force due to the spatial deformation is shown.展开更多
Operating point drift over large temperature spans can significantly degrade the performance of servo valves.The direction and magnitude of the deviation of the operating point are uncertain.To analyze and evaluate th...Operating point drift over large temperature spans can significantly degrade the performance of servo valves.The direction and magnitude of the deviation of the operating point are uncertain.To analyze and evaluate the mechanism of this complex system with a multi-level structure and multi-variables,it is necessary to construct a theoretical model with a clear physical concept to describe it.However,since the physical processes contain complex variations of structural parameters and flow properties,there is a problem of simplifying approximations in deriving analytical mathematical relations.The advantages of multi-physics field numerical analysis can compensate for this shortcoming of analytical formulations.Based on this,we constructed a whole-valve transfer function model to realize the mechanism analysis and evaluate the operating point drift when a thermal effect acts on a servo valve.The results show that the asymmetric fit relationship between the armature-nozzle assemblies is an important reason for the drift of the operating point caused by the thermal effect.Differences in structural parameters and fluid medium characteristics at different temperatures lead to nonlinear changes in the operating point.When the deviation angle reaches±1°,an increase in temperature will cause the absolute value of the tangent slope of the displacement deviation of the spool to decrease from 1.44×10^(−5) m/℃to 1.25×10^(−6) m/℃.The influence of the deviation angle is reflected in the change in the absolute value of the tangent slope of the pressure deviation from 1.14×10^(3) Pa/℃to 110 Pa/℃.展开更多
文摘Objective The use of lasers has been an important part of urology in the treatment of stone and prostate disease.The thermal effects of lasers in lithotripsy have been a subject of debate over the years.The objective of this review was to assess the current state of knowledge available on the thermal effects of lasers in lithotripsy,as well as explore any new areas where studies are needed.Methods In August 2022,a keyword search on Google Scholar,PubMed,and Scopus for all papers containing the phrases“thermal effects”AND“laser”AND“lithotripsy”AND“urology”was done followed by citation jumping to other studies pertaining to the topic and 35 relevant papers were included in our study.The data from relevant papers were segregated into five groups according to the factor studied and type of study,and tables were created for a comparison of data.Results Temperature above the threshold of 43℃ was reached only when the power was>40 W and when there was adequate irrigation(at least 15–30 mL/min).Shorter lasing time divided by lithotripsy time or operator duty cycles less than 70%also resulted in a smaller temperature rise.Conclusion At least eight factors modify the thermal effects of lasers,and most importantly,the use of chilled irrigation at higher perfusion rates,lower power settings of<40 W,and with a shorter operator duty cycle will help to prevent thermal injuries from occurring.Stones impacted in the ureter or pelvi-ureteric junction further increase the probability of thermal injuries during laser firing.
基金supported by the National Natural Science Fund of China (Grant Nos.U22A20166 and 52374131)the Shenzhen Science and Technology Program (Grant No.JCYJ20220531102012028)the Young Elite Scientists Sponsorship Program by CAST.
文摘The stimulation of shale reservoirs frequently involves significant shear failure,which is crucial for creating fracture networks and enhancing permeability to boost production.As the depth of extraction increases,the impact of elevated temperatures on the anisotropic shear strength and failure mechanisms of shale becomes pronounced,yet there is a notable lack of relevant research.This study conducts,for the first time,direct shear experiment on shales at four different temperatures and seven bedding angles.By employing acoustic emission(AE)and digital image correlation(DIC)techniques,the evolution of damage and the mechanism of crack propagation under anisotropic direct shearing at varying temperatures is revealed.The results indicate that both shear displacement and strength of shale increase with temperature across different bedding angles.Additionally,shale demonstrates distinct brittle failure characteristics under various conditions during direct shearing tests.The types of anisotropic shear failure observed under the influence of temperature include central shearing fracture,central shearing with secondary fracture,and deflected slip along the bedding.Moreover,the temperature effect enhances shear-induced crack propagation along bedding planes.Shear failure in shale predominantly occurs during higher loading stages,which coincide with a substantial amount of AE signals.Finally,the introduction of the anisotropy index and temperature sensitivity coefficient further elucidates the interaction mechanism between thermal effects and anisotropy.This study offers a novel methodology to explore the anisotropic shear failure behavior of shale under elevated temperatures,and also provides crucial theoretical and experimental insights into shear failure behavior relevant to practical shale reservoir stimulation.
基金financially supported by the Ph.D. start-up funds of Jiangxi Science and Technology Normal University (Nos. 2023BSQD11, 2023BSQD13)Jiangxi Province Key Laboratory of Organic Functional Molecules (No. 2024SSY05141)。
文摘The exploitation of organic-inorganic hybrid perovskites(OIHPs) as active layer materials for typical sandwich-structured resistive memories has attracted widespread interest due to the property of low power consumption and fast switching. However, the inherent thermal instability of perovskites limits the application of OIHPs-based resistive memories under extreme conditions, while the infiuence of thermal effects on their resistance change characteristics remains unclear. Herein, a novel 2D <100>-oriented high-temperature resistant OIHP [(BIZ-H)_(2)(PbBr_(4))]n(BIZ = benzimidazole) is prepared as an active layer material to fabricate FTO/[(BIZ-H)_(2)(PbBr_(4))]n/Ag resistive memory with excellent thermal reproducibility and stability up to 120℃. The increase in temperature leads to a decrease in the PbBr_(6) octahedral distortion in the crystal structure, an increase in hydrogen bonding between the(BIZ-H)+cation and the(PbBr_(4))_(n)^(2n-)layer, and a shortening of the spacing of the inorganic layers, which is found to result in the creation and predominance of thermally activated traps with increasing temperature. This work provides a new direction for the next generation of OIHPs-based resistive memories with high-temperature tolerance.
基金funded by the Independent Innovation Project of Changjiang Institute of Survey,Planning,Design and Research Corporation (CX2020Z32)supported by the National Natural Science Foundation of China (Grant Numbers42204006 and 42104028)the Open Fund of Hubei Luojia Laboratory (Grant Numbers 230100020 and 230100019)
文摘The monument thermal effect(MTE)displacements could result in periodical signals with several mil-limeters magnitudes in the vertical and horizontal GPS position time series.However,the interaction ofvarious origins of periodic signals in GPS observations makes it difficult to isolate the millimeter-levelMTE displacement from other signals and noises.In this study,to assess the diurnal and semidiurnalsignals induced by MTE,we processed 12 very short GPS baselines(VSGB)with length<150 m.Themonument pairs for each baseline differ in their heights,horizontal structure,or base foundations.Meanwhile,two zero-baselines were also processed as the control group.Results showed that the sea-sonal signals observed in VSGB time series in the horizontal and vertical directions,were mainly inducedby seasonal MTE.Time-varying diurnal and semidiurnal signals with amplitude up to 4 mm wereobserved in the vertical direction for baselines with monument height difference(MHD)larger than10 m.Horizontal diurnal signal with an amplitude of about 2 mm was also detected for baselines withnon-axisymmetric monument structure.The orientation of the detected horizontal displacement wascoherent with the direction of daily temperature variation(DTV)driven by direct solar radiation,whichindicates that the diurnal and semidiurnal signals are likely induced by MTE.The observed high-frequency MTE displacements,if not well modeled and removed,may propagate into spurious long-term signals and bias the velocity estimation in the daily GPS time series.
基金supported by National Natural Science Foundation of China(No.52177130)the Key Projects for Industrial Prospects and Core Technology Research in Suzhou City(No.SYC2022029)。
文摘Dielectric barrier discharge(DBD)plasma excited by a high-frequency alternating-current(AC)power supply is widely employed for the degradation of volatile organic compounds(VOCs).However,the thermal effect generated during the discharge process leads to energy waste and low energy utilization efficiency.In this work,an innovative DBD thermally-conducted catalysis(DBD-TCC)system,integrating high-frequency AC-DBD plasma and its generated thermal effects to activate the Co/SBA-15 catalyst,was employed for toluene removal.Specifically,Co/SBA-15 catalysts are closely positioned to the ground electrode of the plasma zone and can be heated and activated by the thermal effect when the voltage exceeds 10 k V.At12.4 k V,the temperature in the catalyst zone reached 261℃ in the DBD-TCC system,resulting in an increase in toluene degradation efficiency of 17%,CO_(2)selectivity of 21.2%,and energy efficiency of 27%,respectively,compared to the DBD system alone.In contrast,the DBD thermally-unconducted catalysis(DBD-TUC)system fails to enhance toluene degradation due to insufficient heat absorption and catalytic activation,highlighting the crucial role of AC-DBD generated heat in the activation of the catalyst.Furthermore,the degradation pathway and mechanism of toluene in the DBD-TCC system were hypothesized.This work is expected to provide an energy-efficient approach for high-frequency AC-DBD plasma removal of VOCs.
基金Project (50925521) supported by the National Natural Science Fund for Distinguished Young Scholars of China
文摘Molecular dynamics （MD） simulations of monocrystalline copper （100） surface during nanomachining process were performed based on a new 3D simulation model. The material removal mechanism and system temperature distribution were discussed. The simulation results indicate that the system temperature distribution presents a roughly concentric shape, a steep temperature gradient is observed in diamond cutting tool, and the highest temperature is located in chip. Centrosymmetry parameter method was used to monitor defect structures. Dislocations and vacancies are the two principal types of defect structures. Residual defect structures impose a major change on the workpiece physical properties and machined surface quality. The defect structures in workpiece are temperature dependent. As the temperature increases, the dislocations are mainly mediated from the workpiece surface, while the others are dissociated into point defects. The relatively high cutting speed used in nanomachining results in less defect structures, beneficial to obtain highly machined surface quality.
文摘A DC to 5GHz series MEMS switch is designed and fabricated for wireless communication applications,and thermal effect and power handling of the series switch are discussed.The switch is made on glass substrate,and gold platinum contact is used to get a stable and little insert loss.From DC to 5GHz,0 6dB insertion loss,30dB isolation,and 30μs delay are demonstrated.Thermal effect of the switch is tested in 85℃ and -55℃ atmosphere separately.From DC to 4GHz,the insert loss of the switch increases 0 2dB in 85℃ and 0 4dB in -55℃,while the isolation holds the same value as that in room temperature.To measure the power handling capability of the switch,we applied a continuous RF power increasing from 10dBm to 35 1dBm with the step of 1 0dBm across the switch at 4GHz.The switch keeps working and shows a decrease of the insert loss for 0 1～0 6dB.The maximum continuous power handling (35 1dBm,about 3 24W) is higer than the reported value of shunt switch (about 420mW),which implies series switches have much better power handling capability.
文摘The objective of this paper is to investigate the effect of water temperature on cavitation characteristics in a turbopump inducer,a series of experiments at different temperatures have been conducted in a newly developed visualization test facility.It is found that higher temperature shows little influence on the non-cavitation performance and breakdown characteristic in the investigated range.The relationship between cavitation development and pressure fluctuation has been discussed in detail.Higher temperature displays a remarkable stabilization effect on the cavitation excited pressure.In particular,the inception cavitation numbers of both the super-synchronous rotating cavitation and synchronous rotating cavitation are decreased at higher temperatures,and the corresponding frequencies are not affected,while the amplitudes are distinctly reduced,and the occurrence range of synchronous rotating cavitation is significantly narrowed.A generalized RayleighPlesset equation has been employed to account for the thermal effect on the bubble development,which may provide a deep insight in understanding the experimental results.Thermal effect is found to act as a remarkable dissipation mechanism to suppress the bubble growth,smooth the collapse.In particular,the excited pressure during collapse is smaller at higher temperatures,which may lead to the stabilization effect of high temperature in this study.
基金co-supported by the National Natural Science Foundation of China (No. 51505338 and No. 51475332)the Youths Science Foundation of Zhejiang (No. LQ16E050004 and No. LQ17E050003)
文摘A thermal hydraulic model based on the lumped parameter method is presented to analyze the load-carrying capacity of a slipper pair in an aviation axial-piston pump under specified operating conditions. Both theoretical and experimental results are presented to demonstrate the validity of the thermal hydraulic model. The results illustrate that the squeezing force and thermal wedge bearing force are the main factors that affect the film thickness and load-carrying capacity.At high oil temperature and high load pressure, the film thickness decreases with increasing clamping force due to a combined action of the squeezing bearing force and the thermal wedge bearing force, but the load-carrying capacity will increase. An increase of the film thickness is proven to be beneficial under high shaft rotational speed but especially dangerous as it strongly increases the ripple amplitude of the film thickness, which leads to decreasing the load-carrying capacity. The structural parameters of the slipper can be optimized to achieve desired performance, such as the slipper radius ratio and orifice length diameter ratio. To satisfy the requirement of the load-carrying capacity, the slipper radius ratio should be selected from 1.4 to 1.8, and the orifice length diameter ratio should be selected from 4 to 5.
基金supported by National Natural Science Foundation of China(Grant No. 50979004)Doctor Reserch Fund of Univercity of China(Grant No. 20080070027)
文摘A key design issue related to the turbopump of the rocket engine is that cavitation occurs in cryogenic fluids when the fluid pressure is lower than the vapor pressure at a local thermodynamic state. Cavitation in cryogenic fluids generates substantial thermal effects and strong variations in fluid properties, which in turn alter the cavity characteristics. To date, fewer investigate the thermal effect on cavitation in cryogenic fluids clearly by the numerical methods due to the difficulty of the heat transfer in the phase change process. In order to study the thermal effect on cavitation in cryogenic fluid, computations are conducted around a 2D quarter caliber hydrofoil in liquid nitrogen and hydrogen respectively by implementing modified Merkle cavitation model, which accounts for the energy balance and variable thermodynamic properties of the fluid. The numerical results show that with the thermal effect, the vapour content in constant location decreases, the cavity becomes more porous and the interface becomes less distinct which shows increased spreading while getting shorter in length. In the cavity region, the temperature around the cavity depresses due to absorb the evaporation latent heat and the saturation pressure drops. When the vapour volume fraction is higher, the temperature depression and pressure depression becomes larger. It is also observed that a slight temperature rise is found above the reference fluid temperature at the cavity rear end attributed to the release of latent heat during the condensation process. When the fluid is operating close to its critical temperature, thermal effects on cavitation are more obviously in both the liquid nitrogen and hydrogen. The thermal effect on cavitation in liquid hydrogen is more distinctly compared with that in liquid nitrogen due to the density ratio, vapour pressure and other variable properties of the fluid. The investigation provides aid for the design of the cryogenic pump of the liquid rocket.
基金finically supported by Joint Found for Equipment Advance Research and Aerospace Science and Technology of China(No.6141B061401)Fund for Distinguished Young Scholars in Shaanxi Province of China(No.2018-JC-009)。
文摘This paper reports the modeling method and outcomes of mechanical performance and damage evolution of single-lap bolted composite interference-fit joints under extreme temperatures.The anisotropic continuum damage model involving thermal effects is established on continuum damage mechanics which integrates the shear nonlinearity constitutive relations characterized by Romberg-Osgood equation.The temperature-induced modification of thermal strains and material properties is incorporated in stress-strain analysis,extended 3 D failure criteria and exponential damage evolution rules.The proposed model is calibrated and employed to simulate behavior of composite joints in interference fitting,bolt preloading,thermal and bearing loading processes,during which the influence of interference-fit sizes,preload levels,laminate layups and service temperatures is thoroughly investigated.The predicated interfacial behavior,bearing response and failure modes are in good agreement with experimental tests.The numerical model is even capable of reflecting some non-intuitive experimental findings such as residual stress relaxation and matrix softening at elevated temperatures.
文摘This paper studies the thermal effect of the cable-stayed bridge tower based on full time accurate measurement and finite element analysis on Xiantao Hanjiang River Highway Bridge. The measured results and the displacement variation of top tower show that the tower rotates periodically when it is exposed in sunshine. But the tower column will not decline when there is no sunshine. In spite of in winter or in summer, the period when the tower column changed smallest is from 0∶00 am to 5∶00 am. The time period when the tower column has maximum deviation lags behind the time when the tower column has maximum temperature difference, and this phenomenon is obvious in winter. The conclusions also have directive value in predicting the tower deformations and their directions in construction control of cable-stayed bridge, and in verifying the finite element program.
基金Project supported by the National Natural Science Foundation of China(Nos.51578496 and 51878603)the Zhejiang Provincial Natural Science Foundation of China(No.LZ16E080001)。
文摘In this study, we examined the thermal effects throughout the process of the placement of span-scale girder segments on a 6×110-m continuous steel box girder in the Hong Kong-Zhuhai-Macao Bridge. Firstly, when a span-scale girder segment is temporarily stored in the open air, temperature gradients will significantly increase the maximum reaction force on temporary supports and cause local buckling at the bottom of the girder segment. Secondly, due to the temperature difference of the girder segments before and after girth-welding, some residual thermal deflections will appear on the girder segments because the boundary conditions of the structure are changed by the girth-welding. Thirdly, the thermal expansion and thermal bending of girder segments will cause movement and rotation of bearings, which must be considered in setting bearings. We propose control measures for these problems based on finite element method simulation with field-measured temperatures. The local buckling during open-air storage can be avoided by reasonably determining the appropriate positions of temporary supports using analysis of overall and local stresses. The residual thermal deflections can be overcome by performing girth-welding during a period when the vertical temperature difference of the girder is within 1 °C, such as after 22:00. Some formulas are proposed to determine the pre-set distances for bearings, in which the movement and rotation of the bearings due to dead loads and thermal loads are considered. Finally, the feasibility of these control measures in the placement of span-scale girder segments on a real continuous girder was verified: no local buckling was observed during open-air storage;the residual thermal deflections after girth-welding were controlled within 5 mm and the residual pre-set distances of bearings when the whole continuous girder reached its design state were controlled within 20 mm.
基金the National Science Foundation of China (31670399 and 31670422)
文摘We maintained gravid Chinese skinks(Plestiodon chinensis) at three constant temperatures(25, 28 and 31 °C) during gestation, and randomly assigned eggs from each female to one of the same three temperatures for incubation to determine maternal thermal effects on female reproduction and hatchling phenotype. Maternal temperature affected egg-laying date, hatching success and hatchling linear size(snout-vent length, SVL) but not clutch size, egg size, egg component, and embryonic stage at laying. More specifically, females at higher temperatures laid eggs earlier than did those at low temperatures, eggs laid at 31 °C were less likely to hatch than those laid at 25 °C or 28 °C, and hatchlings from eggs laid at 31 °C were smaller in SVL. Our finding that maternal temperature(pre-ovipositional thermal condition) rather than incubation temperature(post-ovipositional thermal condition) affected hatching success indicated that embryos at early stages were more vulnerable to temperature than those at late stages. Our data provide an inference that moderate maternal temperatures enhance reproductive fitness in P. chinensis.
基金Project supported by the Opening Project of Key Laboratory of Microelectronics Devices&Integrated Technology,Institute of Microelectronics of Chinese Academy of Sciences,the National High Technology Research and Development Program of China(Grant No.2014AA032901)the National Natural Science Foundation of China(Grant Nos.61574166,61334007,61306117,61322408,61221004,and 61274091)+1 种基金Beijing Training Project for the Leading Talents in S&T,China(Grant No.Z151100000315008)the CAEP Microsystem and THz Science and Technology Foundation,China(Grant No.CAEPMT201504)
文摘Three-dimensional（3D） crossbar array architecture is one of the leading candidates for future ultra-high density nonvolatile memory applications. To realize the technological potential, understanding the reliability mechanisms of the3 D RRAM array has become a field of intense research. In this work, the endurance performance of the 3D 1D1 R crossbar array under the thermal effect is investigated in terms of numerical simulation. It is revealed that the endurance performance of the 3D 1D1 R array would be seriously deteriorated under thermal effects as the feature size scales down to a relatively small value. A possible method to alleviate the thermal effects is provided and verified by numerical simulation.
文摘This study examined the thermal effects of building′s external wall surfaces, using observational data of spatial-temporal distribution of surface temperature, air temperature, and heat flux into and out of external surface. Results indicate that external wall surface temperature and nearby air temperature vary with the change of orientation, height and season. In general, the external wall surface temperature is lower near the ground, and is higher near the roof, than nearby air temperature. But north wall surface temperature is mostly lower than nearby air temperature at the same height; south wall surface temperature during the daytime in December, and west wall surface temperature all day in August, is respectively higher than nearby air temperature. The heat fluxes into and out of external wall surfaces show the differences that exist in the various orientations, heights and seasons. In December, south wall surface at the lower sites emits heat and north wall surface at the higher sites absorbs heat. In April, all external wall surfaces, emit heat near the ground and absorb heat near the roof. In August, west wall surface all day emits heat, and other wall surfaces just show the commensurate behavior with that in April.
基金funding by the German Federal Ministry of Economics and Technology (BMWi) under contract No.02E10377the French National Radioactive Waste Management Agency (Andra)
文摘Thermal effects on the Callovo-Oxfordian and Opalinus clay rocks for hosting high-level radioactive waste were comprehensively investigated with laboratory and in situ experiments under repository relevant conditions:(1) stresses covering the range from the initial lithostatic state to redistributed levels after excavation,(2) hydraulic drained and undrained boundaries, and(3) heating from ambient temperature up to 90℃-120℃ and a subsequent cooling phase. The laboratory experiments were performed on normal-sized and large hollow cylindrical samples in various respects of thermal expansion and contraction, thermally-induced pore water pressure, temperature influences on deformation and strength, thermal impacts on swelling, fracture sealing and permeability. The laboratory results obtained from the samples are consistent with the in situ observations during heating experiments in the underground research laboratories at Bure and Mont-Terri. Even though the claystones showed significant responses to thermal loading, no negative effects on their favorable barrier properties were observed.
基金the National Natural Science Foundation of China(Nos.10872126 and 10772113)
文摘The dynamic performance of composite flexible multi-body system under the simultaneous action of thermal fields and driving constraint is analyzed. Based on strain-displacement relation of the Mindlin plate theory which includes transverse shear deformation, and considering thermal effect, variation equations of laminated plate are derived by the principle of virtual work. The finite element method is used for discretization. According to kinematics constraint relation, dynamic equations for spatial slider-crank system are established. Simulation results show that spatial deformation （torsion deformation） appears in the multi-layered composite slider-crank mechanism which is simulated with planar motions. Furthermore, the influence of coupling between thermal expansion and flexible deformations of non-symmetrical composite plates on the large overall motion under the uniform temperature field is investigated. Finally, significant change in constraint force due to the spatial deformation is shown.
基金supported by the Civil Aircraft Research Project(No.MJ-2016-S-54),China。
文摘Operating point drift over large temperature spans can significantly degrade the performance of servo valves.The direction and magnitude of the deviation of the operating point are uncertain.To analyze and evaluate the mechanism of this complex system with a multi-level structure and multi-variables,it is necessary to construct a theoretical model with a clear physical concept to describe it.However,since the physical processes contain complex variations of structural parameters and flow properties,there is a problem of simplifying approximations in deriving analytical mathematical relations.The advantages of multi-physics field numerical analysis can compensate for this shortcoming of analytical formulations.Based on this,we constructed a whole-valve transfer function model to realize the mechanism analysis and evaluate the operating point drift when a thermal effect acts on a servo valve.The results show that the asymmetric fit relationship between the armature-nozzle assemblies is an important reason for the drift of the operating point caused by the thermal effect.Differences in structural parameters and fluid medium characteristics at different temperatures lead to nonlinear changes in the operating point.When the deviation angle reaches±1°,an increase in temperature will cause the absolute value of the tangent slope of the displacement deviation of the spool to decrease from 1.44×10^(−5) m/℃to 1.25×10^(−6) m/℃.The influence of the deviation angle is reflected in the change in the absolute value of the tangent slope of the pressure deviation from 1.14×10^(3) Pa/℃to 110 Pa/℃.
