The equivalence between multilayered barriers regarding diffusion and adsorption was studied.The bottom boundary of the liner system is defined by assuming concentration continuous and flux continuous conditions of th...The equivalence between multilayered barriers regarding diffusion and adsorption was studied.The bottom boundary of the liner system is defined by assuming concentration continuous and flux continuous conditions of the contaminant between the bottom liner layer and the underlying soil.Five different liner systems were compared in terms of solute breakthrough time.The results of the analysis showed that breakthrough time of the hydrophobic organic compounds for a 2-meter-thick compacted clay liner(CCL)could be 3-4 orders of magnitude is greater than the breakthrough time for a geosynthetic clay liner(GCL)composite liner.The GM/GCL and GM/CCL composite liner systems provide a better diffusion barrier for the hydrophilic organic compounds than that for the hydrophobic compounds due to their different Henry's coefficient.The calculated breakthrough times of the organic contaminants for the Chinese standard liner systems were found to be generally greater than those for the GCL alternatives,for the specific conditions examined.If the distribution coefficient increases to 2.8 for the hydrophobic compounds or 1.0 for the hydrophilic compounds,the thickness of the attenuation layer needed to achieve the same breakthrough time as the standard liner systems can be reduced by a factor of about 1.9-2.4.As far as diffusive and adsorption contaminant transport are concerned,GM or GCL is less effective than CCL.展开更多
According to relevant new regulations in China,a composite liner system involving geosynthetic materials must be installed at the bottom of an expanded landfill.The deformation and integrity of the composite liner und...According to relevant new regulations in China,a composite liner system involving geosynthetic materials must be installed at the bottom of an expanded landfill.The deformation and integrity of the composite liner under a variety of factors are important issue to be considered in the design of a landfill expansion.In this paper,we investigate the strain distribution in geosynthetic materials within the composite liner system of expanded landfills,including strains in geosynthetic materials resulting from overall settlement and lateral movement of landfills,localized subsidence in landfills,and differential settlement around gas venting wells.The allowable strains of geosynthetic materials are discussed based on the results of tensile tests,and the corresponding design criteria for composite liner systems are proposed.Meanwhile,practical measures allowing strain control in geosynthetic materials used in landfill engineering are proposed.展开更多
This study is to identify the critical interface in a geosynthetic multilayer liner system by examining the effects of the interface shear strength of liner components, leachate level, leachate buildup cases, and peak...This study is to identify the critical interface in a geosynthetic multilayer liner system by examining the effects of the interface shear strength of liner components, leachate level, leachate buildup cases, and peak and residual interface strengths. According to current landfill design procedures, conducting stability analysis along the same interface at both the back slope and base may result in a non-conservative result. The critical interfaces with the minimum factor of safety are generally found at different locations along the back slope and base. The critical interface for a multilayer liner system cannot simply be assumed during stability analysis. It can shift from one interface to another with changes in the leachate level and with different leachate buildup cases. The factor of safety for an interface with a high friction angle and low apparent cohesion generally drops much more quickly than it does under inverse conditions when the leachate level increases. The failure interface in a liner system under residual conditions is usually different from the failure interface under peak conditions.展开更多
The design of roof frame is one of the most important parts of LNG tank design.In China,however,the calculation of roof frame system of extra-large LNG tanks is currently faced with a series of problems.For example,th...The design of roof frame is one of the most important parts of LNG tank design.In China,however,the calculation of roof frame system of extra-large LNG tanks is currently faced with a series of problems.For example,there is no united yardstick on buckling characteristic value,the calculation is based on many assumptions,and the calculation is inconsistent with domestic specifications and stipulations.In view of these problems,the material non-linearity and structural non-linearity were introduced and the initial defect was taken into consideration.Then,the large non-linear finite element calculation software ABAQUS was adopted to carry out modeling on the roof frame and liner system of extra-large LNG tanks and calculate and analyze the force applied on them and their stability.Finally,a complete set of design algorithm for the roof frame and liner system of extra-large LNG tanks was established and applied to the design of a certain LNG tank(20×10^(4)m^(3))in China.It is indicated that this design algorithm can simulate the actual situations accurately.This design algorithm is structurally composed of shell units and beam units,and it is connected in the pattern of common node.Besides,force calculation is conducted in 10 operational modes and the buckling calculation in 7 operational modes,including all operational modes in the construction process of roof frame and liner system of LNG tanks.It is also revealed that the maximum stress on the roof frame is 125.7 MPa,that on the liner is 101.4 MPa and the minimum safety coefficient used for buckling calculation is 2.57.Under this system,the force and stability of the roof frame of LNG tanks are satisfactory.The research results can be used as reference for relevant design and calculation.展开更多
BACKGROUND Medial dished(MD)liner designs for cruciate-retaining(CR)total knee arthroplasty(TKA)are a relatively novel development.MD tibial inserts have a more constraining medial side,which allows for more similar k...BACKGROUND Medial dished(MD)liner designs for cruciate-retaining(CR)total knee arthroplasty(TKA)are a relatively novel development.MD tibial inserts have a more constraining medial side,which allows for more similar kinematics and function to a native knee.AIM To evaluate the clinical results and patient-reported outcomes after CR TKA procedures utilizing a kinematically designed medial dish system.METHODS A multicenter,retrospective cohort review of 139 primary elective TKAs utilizing a kinematically designed CR Knee System(JOURNEY™II CR MD;Smith and Nephew,Memphis,TN,United States)at three different institutions with a minimum of two years of follow-up.Demographic information,clinical outcomes,and patient-reported outcome measures were collected and analyzed.RESULTS With up to 3.7 years from surgery,overall implant survivorship was 98.6%.There were significant postoperative increases in the average Knee Injury and Osteoarthritis Outcome Score for Joint Replacement scores(17.4 at 6 months,26.1 points at two years or more,P<0.001).CONCLUSION The combination of high implant survivorship and substantial improvements in patient-reported outcome measures suggests that the medial dish tibial insert represents a safe and effective option within TKA.Additional investigation is necessary to evaluate the long-term survivorship of this design.展开更多
Developing advanced acoustic treatments,such as the Multi-Degree-of-Freedom(MDOF)septum liner,to realize the broadband noise reduction is critical for silent aeroengines.This study investigates experimentally the MDOF...Developing advanced acoustic treatments,such as the Multi-Degree-of-Freedom(MDOF)septum liner,to realize the broadband noise reduction is critical for silent aeroengines.This study investigates experimentally the MDOF septum liner and its impedance model on the Beihang Grazing Flow Duct(BGFD)setup,over a wide frequency range under grazing flows up to 0.5 Mach number and Sound Pressure Level(SPL)up to 150 dB,typically encountered in aeroengine nacelles.Several specimens varying in the numbers,types,and depths of septa among units are designed,fabricated,and measured.Their impedances and Transmission Losses(TL)are obtained using the mirror-based multimodal straightforward method and the mode decomposition technique,respectively.Generally,the model predictions show good agreement with the educed impedances in all cases,and such liners with a large-porosity facesheet exhibit low acoustic nonlinearities in the presence of high SPL,especially under high-velocity grazing flows.Moreover,a MDOF liner we delicately designed,compared with a conventional broadband three-layer perforated liner as the reference,is close to the resonant state at more frequencies and thus has higher and wider measured TL spectra almost from 1 kHz up to 10 kHz at studied Mach numbers,under the premise of saving 22.7 mm in the thickness.These show that,the MDOF septum liner,if well designed,can achieve an ultra-broadband efficient sound attenuation using more limited spaces in complex aeroacoustic environments.展开更多
This study is an optimized extension based on the authors’previous research on the tribo-chemical reaction under constant temperature field of two-stroke internal combustion engines(ICEs).It establishes a coupled ana...This study is an optimized extension based on the authors’previous research on the tribo-chemical reaction under constant temperature field of two-stroke internal combustion engines(ICEs).It establishes a coupled analysis model that considers the tribo-chemical reactions,dynamic contact,and interface lubrication of the piston ring-cylinder liner(PRCL)system under transient temperature conditions.In this study,for the first time,the prediction of the tribofilm thickness and its influence on the surface micro-topography(the comprehensive roughness)are coupled in the working temperature field of the PRCL system,forming an effective model framework and providing a model basis and analytical basis for subsequent research.This study findings reveal that by incorporating temperature and tribofilm into the simulation model,the average friction deviation throughout the stroke decreases from 8.92%to 0.93%when compared to experimental results.Moreover,the deviation during the combustion regime reduces from 39.56%to 7.34%.The proposed coupled model provides a valuable tool for the evaluation of lubrication performance of the PRCL system and supports the analysis software forward design in two-stroke ICEs.展开更多
In this study,a machine vision method is proposed to characterize 3D roughness of the textured surface on cylinder liner processed by plateau honing.The least absolute value(L∞)regression robust algorithm and Levenbe...In this study,a machine vision method is proposed to characterize 3D roughness of the textured surface on cylinder liner processed by plateau honing.The least absolute value(L∞)regression robust algorithm and Levenberg-Marquardt(LM)algorithm are employed to reconstruct image reference plane.On this basis,a single-hidden layer feedforward neural network(SLFNN)based on the extreme learning machine(ELM)is employed to model the relationship between high frequency information and 3D roughness.The characteristic parameters of Abbott-Firestone curve and 3D roughness measured by a confocal microscope are used to construct ELM-SLFNN prediction model for 3D roughness.The results indicate that the proposed method can effectively characterize 3D roughness of the textured surface of cylinder liner.展开更多
This paper provides a numerical analysis model of unsteady heat trans-fer in piston-liner set of an internal combustion engine.The model simulates the un-steady heat transfer process among the combustion mixture,pisto...This paper provides a numerical analysis model of unsteady heat trans-fer in piston-liner set of an internal combustion engine.The model simulates the un-steady heat transfer process among the combustion mixture,piston set,lubricantfilm,liner and coolant in a whole engine cycle,and can predict the temperature fluc-tuation and distribution on piston crown,inner surface of liner,piston ring and thelubricant film.A computer program is developed to calculate the unsteady heat trans-fer process of piston-liner system in a water-cooled diesel engine.展开更多
BACKGROUND Total hip arthroplasty is a safe and effective procedure.To improve survivorship,ultrahigh molecular weight polyethylene hip liners with antioxidants have been developed.Additive antioxidant was deployed to...BACKGROUND Total hip arthroplasty is a safe and effective procedure.To improve survivorship,ultrahigh molecular weight polyethylene hip liners with antioxidants have been developed.Additive antioxidant was deployed to reduce oxidation and consequential wear,loosening,or osteolysis.A unique manufacturing process was utilized for two such hip liners,the Novation®and Alteon®XLE hip liners and this research represents the first large series on this specific material.The study hypothesis was that Novation and Alteon XLE hip liners have similar short-term survivorship as other manufacturers’antioxidant liners according to procedure and outcome data from the American Joint Replacement Registry(AJRR).AIM To demonstrate similar short-term survivorship of XLE antioxidant hip liners compared to all antioxidant hip liners in AJRR.METHODS Utilizing total hip arthroplasty data from the AJRR,a retrospective review was performed for subjects who underwent implantation of Novation XLE(n=461),Alteon XLE(n=989),or any other antioxidant hip liner(termed the aggregate antioxidant group;n=39964)as of March 31,2022.Survivorship at three years and revision rates were compared statistically between the Novation group and the aggregate antioxidant group as well as the Alteon group and the aggregate antioxidant group.RESULTS Survivorship at three years post-surgery was 99.09%for Novation,97.73%for Alteon,and 97.69%for the aggregate antioxidant group.There were no reports of failure due to wear in either the Novation or Alteon groups.Among the revision categories(fracture,infection,aseptic loosening,instability,mechanical complications,wear,pain,hematoma/wound complications,or other),there were no significant differences identified in either comparison.There were also no significant differences in cumulative percent revision rates up to three years post-surgery for the Novation vs aggregate antioxidant group or the Alteon vs aggregate antioxidant group.CONCLUSION Novation and Alteon XLE hip liner revision rate and survivorship are equivalent to other antioxidant hip liners in the short term.展开更多
During the storage of composite propellants, the migration of plasticizers and other unbonded additives at the interfaces of liner adhesives has garnered significant attention in understanding liner failure mechanisms...During the storage of composite propellants, the migration of plasticizers and other unbonded additives at the interfaces of liner adhesives has garnered significant attention in understanding liner failure mechanisms, aging processes, and safety performance. However, there is currently no non-destructive and quantitative detection method for migration of plasticizers in propellant liner. In this study, we developed a HTPB sensing liner by incorporating conductive fillers-namely carbon black(CB), carbon nanotubes(CNTs), and graphene nanoplatelets(GNP)-into the HTPB matrix. The synergistic interaction between CNTs and GNP facilitates the formation of a tunneling conductive network that imparts electrical conductivity to the HTPB liner. To elucidate the functional relationship between conductivity and nitroglycerin(NG) migration, we applied the HTPB sensing liner onto double base propellant surfaces and measured both the conductivity of the sensing layer and NG migration during a 71°C accelerated aging experiment. The results shows that when CNTs/GNP content reaches 3wt%, there is an exponential correlation between conductivity and NG migration with a fitting degree of 0.9652;the average response sensitivity of ΔR/R0 relative to NG migration is calculated as 41.69, with an average deviation of merely5.67% between NG migrations derived from conductivity fittings compared to those obtained via TGA testing results. Overall, this sensing liner exhibits excellent capabilities for detecting NG migration nondestructively and quantitatively while offering a novel approach for assessing interfacial component migrations as well as debonding defects in propellants-a promising avenue for future self-monitoring strategies regarding propellant integrity.展开更多
The service life of internal combustion engines is significantly influenced by surface defects in cylinder liners.To address the limitations of traditional detection methods,we propose an enhanced YOLOv8 model with Sw...The service life of internal combustion engines is significantly influenced by surface defects in cylinder liners.To address the limitations of traditional detection methods,we propose an enhanced YOLOv8 model with Swin Transformer as the backbone network.This approach leverages Swin Transformer's multi-head self-attention mechanism for improved feature extraction of defects spanning various scales.Integrated with the YOLOv8 detection head,our model achieves a mean average precision of 85.1%on our dataset,outperforming baseline methods by 1.4%.The model's effectiveness is further demonstrated on a steel-surface defect dataset,indicating its broad applicability in industrial surface defect detection.Our work highlights the potential of combining Swin Transformer and YOLOv8 for accurate and efficient defect detection.展开更多
Cerium-aluminum(CeAl)alloy is promising reactive structural materials(RSMs)with significant potential for liner applications.To investigate the thermochemical characteristics of CeAl alloy and the perforation behavior...Cerium-aluminum(CeAl)alloy is promising reactive structural materials(RSMs)with significant potential for liner applications.To investigate the thermochemical characteristics of CeAl alloy and the perforation behavior of its liner impacting steel targets,a CeAl alloy liner with 5 wt%Al content was fabricated,with a cerium(Ce)liner and a copper(Cu)liner used as control.The microstructure and elemental distribution of the CeAl alloy were analyzed using SEM,EDS,and XRD.The thermochemical reaction mechanism of the CeAl alloy was examined through TG-DSC.Penetration experiments were conducted to explore the combined effects of invasion and implosion of CeAl alloy liner against steel target.The results indicate that the addition of Al leads to the formation of Ce_(3)Al intermetallic compounds in the alloy and reduces the apparent activation energy of the Ce-based alloy by around 53.17%,thereby facilitating energy release.The presence of 5 wt%Al increases the calorific value by approximately 24.5%,and this change allows the oxidation process to be divided into three distinct stages.Compared to an inert copper liner,the average penetration diameter of the CeAl_(5) reactive alloy liner increases by around 42.78%.Furthermore,when compared to the Ce liner,the penetration depth of the CeAl_(5) reactive alloy liner increases by approximately 82.64%.展开更多
Polymer-modified bentonite(PMB)is much more effective at containing chemically aggressive liquids than conventional bentonite.The PMB manufacturing process typically utilizes natural,high-quality sodium bentonite(NaB)...Polymer-modified bentonite(PMB)is much more effective at containing chemically aggressive liquids than conventional bentonite.The PMB manufacturing process typically utilizes natural,high-quality sodium bentonite(NaB)owing to its excellent hydrophilicity and swelling capacity.However,calcium bentonite(CaB),which is much more abundant worldwide,is rarely used for containment applications owing to its poor hydrophilicity.This study proposed a polymerization method that transforms sodium-activated calcium bentonite(NCB)into PMB to achieve low hydraulic conductivity(k)to aggressive liquids.The mechanism for its low k was revealed through characterization techniques and analyses(e.g.X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy(SEM),and Brunauer-Emmett-Teller(BET)).The results showed that the PMB had a small amount of polymer elution(indicating better interface stability)and thus exhibited excellent barrier properties under chemically aggressive conditions,with the k of<10^(-11) m/s for 0.6 mol/L NaCl solution,which is four orders of magnitude lower than that of the NCB(k=3×10^(-7) m/s).Various microscopic analyses indicated that the selected monomers were successfully polymerized,and intercalated into and grafted onto the montmorillonite layers of bentonite.The formed polymer network increased the swelling capability of PMB granules,decreased the pore size,and created narrow and tortuous flow pathways leading to a very low k to aggressive liquids.展开更多
The effectiveness of perforated liner with bias flow on the control of combustion instability is investigated.Combustion instabilities result from the coupling between acoustic waves and unsteady combustion heat relea...The effectiveness of perforated liner with bias flow on the control of combustion instability is investigated.Combustion instabilities result from the coupling between acoustic waves and unsteady combustion heat release.Sometimes the phenomenon happens in afterburners of aeroengine and rocket engine,and it always causes damage to flame holders,liner seetions and other engine components.Passive methods,such as perforated liner,are often used to suppress such instabilities in application.In this article,first,a burner testbed is built in order to study the characteristic of this phenomenon.The unstable frequencies and unsta-ble area are investigated experimentally.Then an analytical model,based on"transfer element method",is developed and the numerical results are compared with those from experiments.At last the perforated liner is applied to the burner to suppress the instabilities.The results show that the sound pressure can be greatly reduced by the perforated liner.展开更多
Impact,friction and corrosion from the grinding balls and the grinding medium during the mineral processing result in liner breakage.Liner,made from Hadfield steel or alloyed steel,could not have served in wet grindin...Impact,friction and corrosion from the grinding balls and the grinding medium during the mineral processing result in liner breakage.Liner,made from Hadfield steel or alloyed steel,could not have served in wet grinding environment for more than ten months.Composite liner,made from HCWCI(high Cr white cast iron)and carbon steel,has been developed successfully with liquid-liquid composing process based on LFC(lost foam casting).The microstructure of composite was analyzed with optical microscope,SEM(scanning electron microscope)/EDX energy-dispersive X-ray and XRD(X-ray diffraction).According to micrograph,the combination region of two metals was staggered like dogtooth,no mixtures occurred between two liquid metals,and its interface presented excellent metallurgical bonding state.The results of mechanical property test show that,the hardness of HRC,the fracture toughness,and the bending strength are more than 61,16.5 J/cm2 and 1600 MPa,respectively.Comparison between liners made from bimetal composite and alloyed steel has also been investigated in industrial hematite ball mill.The results of eight months test in wet grinding environment prove that the service life of bimetal composite liner is three times as long as that of one made from alloyed steel.展开更多
In the dry-sliding process of the woven self-lubricating liner which is used in the self-lubricating spherical plain bearing, the friction heat plays an important role in the tribological performances of the liner. It...In the dry-sliding process of the woven self-lubricating liner which is used in the self-lubricating spherical plain bearing, the friction heat plays an important role in the tribological performances of the liner. It has important value to study on the relationship between tribological performances of the liner and the friction heat. Unforttmately, up to now, published work on this relationship is quite scarce. Therefore, the effect of friction heat on the tribological performances of the liner was investigated in the present work. The tribological behaviors of the liner were evaluated by using the high temperature end surface wear tester. Scanning electron microscopy （SEM） was utilized to examine the morphologies of worn surfaces of the liner and study the failure modes. Differential scanning calorimetry （DSC） measurement and X-ray diffraction （XRD） analysis were performed to study the behaviors of the wear debris. The temperature rise on the worn surface was calculated according to classical models. SEM observation shows that the dominating wear mechanism for the liner is mainly affected by friction shear force, contact pressure and friction heat. Higher fusion heat for the wear debris than that for the pure polytetrafluroethylene （PTFE） indicates that the PTFE is the main portion of the wear debris, and, the PTFE in the wear debris shows a higher crystallisation degree owing to the effects of friction shear force and the friction heat. Combining the calculated temperature rise results with the wear rate of the liner, it can be concluded that the effects of temperature rise o n the tribological performances of the liner become more obvious when the temperature rise exceeds the glass transition temperature （Tg） of the PTFE. The wear resistance of the liner deteriorates dramatically when the temperature rise approaches to the melting point （Ton） of the PTFE. The tribological performances of the liner can be improved when the temperature rise exceeds Tg but is far lower than Ton- The present study on the relationship between the temperature rise and the tribological performances of the liner may provide the basis for further understanding of the wear mechanisms of the liner as well as the relationship between the formation of the PTFE transfer film and the friction heat during the dry-sliding of the Finer.展开更多
Hydroxyl-terminated polybutadiene/toluene diisocyanate(HTPB/TDI)system is widely used in composite solid propellants.The migrations of plasticizers and water molecules from solid propellants and surrounding environmen...Hydroxyl-terminated polybutadiene/toluene diisocyanate(HTPB/TDI)system is widely used in composite solid propellants.The migrations of plasticizers and water molecules from solid propellants and surrounding environment to the inhibitor have always been the important issues.This study focuses on the preparation,characterization and anti-migration behavior of graphene oxide(GO)/HTPB nanocomposite liner.The GO/HTPB(GH)composite liners affect the migration of small molecules through a tighter cross-linked structure and weakening function of small molecule adsorption.The anti-migration performance of the liner at different temperatures was analyzed,and the influence of the added amount of GO on the anti-migration performance and adhesion performance was also systematically studied.The overall performance of the liner is optimized when the amount of GO filler is 0.3 wt%.After adding 0.3 wt%GO,the concentration of dioctyl sebacate(DOS)migrated into the liner is decreased by 23.28%,and the concentration of water molecules is decreased by 51.89%,indicating that the introduction of GO can significantly improve the anti-migration performance of the liner.In addition,the bond strength is greatly increased from 0.25 MPa to 0.95 MPa,which meets the application requirements of the current propellant system.This research provides an important way for the preparation of structure-function synergistic anti-migration composite liners.展开更多
基金supported by the National Science Fundfor Distinguished Young Scholars(No.50425825)the National Natural Science Foundation of China(No.50538080)
文摘The equivalence between multilayered barriers regarding diffusion and adsorption was studied.The bottom boundary of the liner system is defined by assuming concentration continuous and flux continuous conditions of the contaminant between the bottom liner layer and the underlying soil.Five different liner systems were compared in terms of solute breakthrough time.The results of the analysis showed that breakthrough time of the hydrophobic organic compounds for a 2-meter-thick compacted clay liner(CCL)could be 3-4 orders of magnitude is greater than the breakthrough time for a geosynthetic clay liner(GCL)composite liner.The GM/GCL and GM/CCL composite liner systems provide a better diffusion barrier for the hydrophilic organic compounds than that for the hydrophobic compounds due to their different Henry's coefficient.The calculated breakthrough times of the organic contaminants for the Chinese standard liner systems were found to be generally greater than those for the GCL alternatives,for the specific conditions examined.If the distribution coefficient increases to 2.8 for the hydrophobic compounds or 1.0 for the hydrophilic compounds,the thickness of the attenuation layer needed to achieve the same breakthrough time as the standard liner systems can be reduced by a factor of about 1.9-2.4.As far as diffusive and adsorption contaminant transport are concerned,GM or GCL is less effective than CCL.
基金Supported by the National Natural Science Foundation of China (50538080)
文摘According to relevant new regulations in China,a composite liner system involving geosynthetic materials must be installed at the bottom of an expanded landfill.The deformation and integrity of the composite liner under a variety of factors are important issue to be considered in the design of a landfill expansion.In this paper,we investigate the strain distribution in geosynthetic materials within the composite liner system of expanded landfills,including strains in geosynthetic materials resulting from overall settlement and lateral movement of landfills,localized subsidence in landfills,and differential settlement around gas venting wells.The allowable strains of geosynthetic materials are discussed based on the results of tensile tests,and the corresponding design criteria for composite liner systems are proposed.Meanwhile,practical measures allowing strain control in geosynthetic materials used in landfill engineering are proposed.
文摘This study is to identify the critical interface in a geosynthetic multilayer liner system by examining the effects of the interface shear strength of liner components, leachate level, leachate buildup cases, and peak and residual interface strengths. According to current landfill design procedures, conducting stability analysis along the same interface at both the back slope and base may result in a non-conservative result. The critical interfaces with the minimum factor of safety are generally found at different locations along the back slope and base. The critical interface for a multilayer liner system cannot simply be assumed during stability analysis. It can shift from one interface to another with changes in the leachate level and with different leachate buildup cases. The factor of safety for an interface with a high friction angle and low apparent cohesion generally drops much more quickly than it does under inverse conditions when the leachate level increases. The failure interface in a liner system under residual conditions is usually different from the failure interface under peak conditions.
基金Project supported by the Special and Significant Project of China National Offshore Oil Corporation“Study on the design of full-containment large LNG storage tank and engineering applications”(No.:CNOOC-KJ125ZDXM14QD-04QD11).
文摘The design of roof frame is one of the most important parts of LNG tank design.In China,however,the calculation of roof frame system of extra-large LNG tanks is currently faced with a series of problems.For example,there is no united yardstick on buckling characteristic value,the calculation is based on many assumptions,and the calculation is inconsistent with domestic specifications and stipulations.In view of these problems,the material non-linearity and structural non-linearity were introduced and the initial defect was taken into consideration.Then,the large non-linear finite element calculation software ABAQUS was adopted to carry out modeling on the roof frame and liner system of extra-large LNG tanks and calculate and analyze the force applied on them and their stability.Finally,a complete set of design algorithm for the roof frame and liner system of extra-large LNG tanks was established and applied to the design of a certain LNG tank(20×10^(4)m^(3))in China.It is indicated that this design algorithm can simulate the actual situations accurately.This design algorithm is structurally composed of shell units and beam units,and it is connected in the pattern of common node.Besides,force calculation is conducted in 10 operational modes and the buckling calculation in 7 operational modes,including all operational modes in the construction process of roof frame and liner system of LNG tanks.It is also revealed that the maximum stress on the roof frame is 125.7 MPa,that on the liner is 101.4 MPa and the minimum safety coefficient used for buckling calculation is 2.57.Under this system,the force and stability of the roof frame of LNG tanks are satisfactory.The research results can be used as reference for relevant design and calculation.
文摘BACKGROUND Medial dished(MD)liner designs for cruciate-retaining(CR)total knee arthroplasty(TKA)are a relatively novel development.MD tibial inserts have a more constraining medial side,which allows for more similar kinematics and function to a native knee.AIM To evaluate the clinical results and patient-reported outcomes after CR TKA procedures utilizing a kinematically designed medial dish system.METHODS A multicenter,retrospective cohort review of 139 primary elective TKAs utilizing a kinematically designed CR Knee System(JOURNEY™II CR MD;Smith and Nephew,Memphis,TN,United States)at three different institutions with a minimum of two years of follow-up.Demographic information,clinical outcomes,and patient-reported outcome measures were collected and analyzed.RESULTS With up to 3.7 years from surgery,overall implant survivorship was 98.6%.There were significant postoperative increases in the average Knee Injury and Osteoarthritis Outcome Score for Joint Replacement scores(17.4 at 6 months,26.1 points at two years or more,P<0.001).CONCLUSION The combination of high implant survivorship and substantial improvements in patient-reported outcome measures suggests that the medial dish tibial insert represents a safe and effective option within TKA.Additional investigation is necessary to evaluate the long-term survivorship of this design.
基金co-supported by the National Natural Science Foundation of China(No.52206039)the Taihang Laboratory of China(No.A2053)+1 种基金the Aeronautical Science Foundation of China(No.20240011051001)the National Key R&D Program of China(No.2021YFB3703900)。
文摘Developing advanced acoustic treatments,such as the Multi-Degree-of-Freedom(MDOF)septum liner,to realize the broadband noise reduction is critical for silent aeroengines.This study investigates experimentally the MDOF septum liner and its impedance model on the Beihang Grazing Flow Duct(BGFD)setup,over a wide frequency range under grazing flows up to 0.5 Mach number and Sound Pressure Level(SPL)up to 150 dB,typically encountered in aeroengine nacelles.Several specimens varying in the numbers,types,and depths of septa among units are designed,fabricated,and measured.Their impedances and Transmission Losses(TL)are obtained using the mirror-based multimodal straightforward method and the mode decomposition technique,respectively.Generally,the model predictions show good agreement with the educed impedances in all cases,and such liners with a large-porosity facesheet exhibit low acoustic nonlinearities in the presence of high SPL,especially under high-velocity grazing flows.Moreover,a MDOF liner we delicately designed,compared with a conventional broadband three-layer perforated liner as the reference,is close to the resonant state at more frequencies and thus has higher and wider measured TL spectra almost from 1 kHz up to 10 kHz at studied Mach numbers,under the premise of saving 22.7 mm in the thickness.These show that,the MDOF septum liner,if well designed,can achieve an ultra-broadband efficient sound attenuation using more limited spaces in complex aeroacoustic environments.
基金supported by the Shandong Provincial Natural Science Foundation(No.ZR2022QE183).
文摘This study is an optimized extension based on the authors’previous research on the tribo-chemical reaction under constant temperature field of two-stroke internal combustion engines(ICEs).It establishes a coupled analysis model that considers the tribo-chemical reactions,dynamic contact,and interface lubrication of the piston ring-cylinder liner(PRCL)system under transient temperature conditions.In this study,for the first time,the prediction of the tribofilm thickness and its influence on the surface micro-topography(the comprehensive roughness)are coupled in the working temperature field of the PRCL system,forming an effective model framework and providing a model basis and analytical basis for subsequent research.This study findings reveal that by incorporating temperature and tribofilm into the simulation model,the average friction deviation throughout the stroke decreases from 8.92%to 0.93%when compared to experimental results.Moreover,the deviation during the combustion regime reduces from 39.56%to 7.34%.The proposed coupled model provides a valuable tool for the evaluation of lubrication performance of the PRCL system and supports the analysis software forward design in two-stroke ICEs.
基金Supported by National Natural Science Foundation of China(Grant No.52075438)Key Research and Development Program of Shaanxi Province of China(Grant No.2024GX-YBXM-268)Open Project of State Key Laboratory for Manufacturing Systems Engineering of China(Grant No.sklms2020010).
文摘In this study,a machine vision method is proposed to characterize 3D roughness of the textured surface on cylinder liner processed by plateau honing.The least absolute value(L∞)regression robust algorithm and Levenberg-Marquardt(LM)algorithm are employed to reconstruct image reference plane.On this basis,a single-hidden layer feedforward neural network(SLFNN)based on the extreme learning machine(ELM)is employed to model the relationship between high frequency information and 3D roughness.The characteristic parameters of Abbott-Firestone curve and 3D roughness measured by a confocal microscope are used to construct ELM-SLFNN prediction model for 3D roughness.The results indicate that the proposed method can effectively characterize 3D roughness of the textured surface of cylinder liner.
文摘This paper provides a numerical analysis model of unsteady heat trans-fer in piston-liner set of an internal combustion engine.The model simulates the un-steady heat transfer process among the combustion mixture,piston set,lubricantfilm,liner and coolant in a whole engine cycle,and can predict the temperature fluc-tuation and distribution on piston crown,inner surface of liner,piston ring and thelubricant film.A computer program is developed to calculate the unsteady heat trans-fer process of piston-liner system in a water-cooled diesel engine.
文摘BACKGROUND Total hip arthroplasty is a safe and effective procedure.To improve survivorship,ultrahigh molecular weight polyethylene hip liners with antioxidants have been developed.Additive antioxidant was deployed to reduce oxidation and consequential wear,loosening,or osteolysis.A unique manufacturing process was utilized for two such hip liners,the Novation®and Alteon®XLE hip liners and this research represents the first large series on this specific material.The study hypothesis was that Novation and Alteon XLE hip liners have similar short-term survivorship as other manufacturers’antioxidant liners according to procedure and outcome data from the American Joint Replacement Registry(AJRR).AIM To demonstrate similar short-term survivorship of XLE antioxidant hip liners compared to all antioxidant hip liners in AJRR.METHODS Utilizing total hip arthroplasty data from the AJRR,a retrospective review was performed for subjects who underwent implantation of Novation XLE(n=461),Alteon XLE(n=989),or any other antioxidant hip liner(termed the aggregate antioxidant group;n=39964)as of March 31,2022.Survivorship at three years and revision rates were compared statistically between the Novation group and the aggregate antioxidant group as well as the Alteon group and the aggregate antioxidant group.RESULTS Survivorship at three years post-surgery was 99.09%for Novation,97.73%for Alteon,and 97.69%for the aggregate antioxidant group.There were no reports of failure due to wear in either the Novation or Alteon groups.Among the revision categories(fracture,infection,aseptic loosening,instability,mechanical complications,wear,pain,hematoma/wound complications,or other),there were no significant differences identified in either comparison.There were also no significant differences in cumulative percent revision rates up to three years post-surgery for the Novation vs aggregate antioxidant group or the Alteon vs aggregate antioxidant group.CONCLUSION Novation and Alteon XLE hip liner revision rate and survivorship are equivalent to other antioxidant hip liners in the short term.
基金funded by Zhijian Laboratory Open Fund,Rocket Force University of Engineering(Grant No.2023-ZJSYS-KF01-03).
文摘During the storage of composite propellants, the migration of plasticizers and other unbonded additives at the interfaces of liner adhesives has garnered significant attention in understanding liner failure mechanisms, aging processes, and safety performance. However, there is currently no non-destructive and quantitative detection method for migration of plasticizers in propellant liner. In this study, we developed a HTPB sensing liner by incorporating conductive fillers-namely carbon black(CB), carbon nanotubes(CNTs), and graphene nanoplatelets(GNP)-into the HTPB matrix. The synergistic interaction between CNTs and GNP facilitates the formation of a tunneling conductive network that imparts electrical conductivity to the HTPB liner. To elucidate the functional relationship between conductivity and nitroglycerin(NG) migration, we applied the HTPB sensing liner onto double base propellant surfaces and measured both the conductivity of the sensing layer and NG migration during a 71°C accelerated aging experiment. The results shows that when CNTs/GNP content reaches 3wt%, there is an exponential correlation between conductivity and NG migration with a fitting degree of 0.9652;the average response sensitivity of ΔR/R0 relative to NG migration is calculated as 41.69, with an average deviation of merely5.67% between NG migrations derived from conductivity fittings compared to those obtained via TGA testing results. Overall, this sensing liner exhibits excellent capabilities for detecting NG migration nondestructively and quantitatively while offering a novel approach for assessing interfacial component migrations as well as debonding defects in propellants-a promising avenue for future self-monitoring strategies regarding propellant integrity.
基金supported by the Scientific and technological key project in Henan Province 22210224002the Natural Science Foundation of Henan Polytechnic University B2021-38.
文摘The service life of internal combustion engines is significantly influenced by surface defects in cylinder liners.To address the limitations of traditional detection methods,we propose an enhanced YOLOv8 model with Swin Transformer as the backbone network.This approach leverages Swin Transformer's multi-head self-attention mechanism for improved feature extraction of defects spanning various scales.Integrated with the YOLOv8 detection head,our model achieves a mean average precision of 85.1%on our dataset,outperforming baseline methods by 1.4%.The model's effectiveness is further demonstrated on a steel-surface defect dataset,indicating its broad applicability in industrial surface defect detection.Our work highlights the potential of combining Swin Transformer and YOLOv8 for accurate and efficient defect detection.
文摘Cerium-aluminum(CeAl)alloy is promising reactive structural materials(RSMs)with significant potential for liner applications.To investigate the thermochemical characteristics of CeAl alloy and the perforation behavior of its liner impacting steel targets,a CeAl alloy liner with 5 wt%Al content was fabricated,with a cerium(Ce)liner and a copper(Cu)liner used as control.The microstructure and elemental distribution of the CeAl alloy were analyzed using SEM,EDS,and XRD.The thermochemical reaction mechanism of the CeAl alloy was examined through TG-DSC.Penetration experiments were conducted to explore the combined effects of invasion and implosion of CeAl alloy liner against steel target.The results indicate that the addition of Al leads to the formation of Ce_(3)Al intermetallic compounds in the alloy and reduces the apparent activation energy of the Ce-based alloy by around 53.17%,thereby facilitating energy release.The presence of 5 wt%Al increases the calorific value by approximately 24.5%,and this change allows the oxidation process to be divided into three distinct stages.Compared to an inert copper liner,the average penetration diameter of the CeAl_(5) reactive alloy liner increases by around 42.78%.Furthermore,when compared to the Ce liner,the penetration depth of the CeAl_(5) reactive alloy liner increases by approximately 82.64%.
基金supported by the National Natural Science Foundation of China(Grant Nos.52478351,52208329)the Shenzhen Science and Technology Innovation Commission(Grant No.JCYJ20240813143306009)support is gratefully acknowledged.
文摘Polymer-modified bentonite(PMB)is much more effective at containing chemically aggressive liquids than conventional bentonite.The PMB manufacturing process typically utilizes natural,high-quality sodium bentonite(NaB)owing to its excellent hydrophilicity and swelling capacity.However,calcium bentonite(CaB),which is much more abundant worldwide,is rarely used for containment applications owing to its poor hydrophilicity.This study proposed a polymerization method that transforms sodium-activated calcium bentonite(NCB)into PMB to achieve low hydraulic conductivity(k)to aggressive liquids.The mechanism for its low k was revealed through characterization techniques and analyses(e.g.X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),scanning electron microscopy(SEM),and Brunauer-Emmett-Teller(BET)).The results showed that the PMB had a small amount of polymer elution(indicating better interface stability)and thus exhibited excellent barrier properties under chemically aggressive conditions,with the k of<10^(-11) m/s for 0.6 mol/L NaCl solution,which is four orders of magnitude lower than that of the NCB(k=3×10^(-7) m/s).Various microscopic analyses indicated that the selected monomers were successfully polymerized,and intercalated into and grafted onto the montmorillonite layers of bentonite.The formed polymer network increased the swelling capability of PMB granules,decreased the pore size,and created narrow and tortuous flow pathways leading to a very low k to aggressive liquids.
基金National Natural Science Foundation of China(50890181)Aeronautical Science Foundation of China(2009ZB51)
文摘The effectiveness of perforated liner with bias flow on the control of combustion instability is investigated.Combustion instabilities result from the coupling between acoustic waves and unsteady combustion heat release.Sometimes the phenomenon happens in afterburners of aeroengine and rocket engine,and it always causes damage to flame holders,liner seetions and other engine components.Passive methods,such as perforated liner,are often used to suppress such instabilities in application.In this article,first,a burner testbed is built in order to study the characteristic of this phenomenon.The unstable frequencies and unsta-ble area are investigated experimentally.Then an analytical model,based on"transfer element method",is developed and the numerical results are compared with those from experiments.At last the perforated liner is applied to the burner to suppress the instabilities.The results show that the sound pressure can be greatly reduced by the perforated liner.
基金Item Sponsored by National Natural Science Foundation of China(50805109)Fundamental Research Funds for Central Universities of China(2011-1a-023)
文摘Impact,friction and corrosion from the grinding balls and the grinding medium during the mineral processing result in liner breakage.Liner,made from Hadfield steel or alloyed steel,could not have served in wet grinding environment for more than ten months.Composite liner,made from HCWCI(high Cr white cast iron)and carbon steel,has been developed successfully with liquid-liquid composing process based on LFC(lost foam casting).The microstructure of composite was analyzed with optical microscope,SEM(scanning electron microscope)/EDX energy-dispersive X-ray and XRD(X-ray diffraction).According to micrograph,the combination region of two metals was staggered like dogtooth,no mixtures occurred between two liquid metals,and its interface presented excellent metallurgical bonding state.The results of mechanical property test show that,the hardness of HRC,the fracture toughness,and the bending strength are more than 61,16.5 J/cm2 and 1600 MPa,respectively.Comparison between liners made from bimetal composite and alloyed steel has also been investigated in industrial hematite ball mill.The results of eight months test in wet grinding environment prove that the service life of bimetal composite liner is three times as long as that of one made from alloyed steel.
文摘In the dry-sliding process of the woven self-lubricating liner which is used in the self-lubricating spherical plain bearing, the friction heat plays an important role in the tribological performances of the liner. It has important value to study on the relationship between tribological performances of the liner and the friction heat. Unforttmately, up to now, published work on this relationship is quite scarce. Therefore, the effect of friction heat on the tribological performances of the liner was investigated in the present work. The tribological behaviors of the liner were evaluated by using the high temperature end surface wear tester. Scanning electron microscopy （SEM） was utilized to examine the morphologies of worn surfaces of the liner and study the failure modes. Differential scanning calorimetry （DSC） measurement and X-ray diffraction （XRD） analysis were performed to study the behaviors of the wear debris. The temperature rise on the worn surface was calculated according to classical models. SEM observation shows that the dominating wear mechanism for the liner is mainly affected by friction shear force, contact pressure and friction heat. Higher fusion heat for the wear debris than that for the pure polytetrafluroethylene （PTFE） indicates that the PTFE is the main portion of the wear debris, and, the PTFE in the wear debris shows a higher crystallisation degree owing to the effects of friction shear force and the friction heat. Combining the calculated temperature rise results with the wear rate of the liner, it can be concluded that the effects of temperature rise o n the tribological performances of the liner become more obvious when the temperature rise exceeds the glass transition temperature （Tg） of the PTFE. The wear resistance of the liner deteriorates dramatically when the temperature rise approaches to the melting point （Ton） of the PTFE. The tribological performances of the liner can be improved when the temperature rise exceeds Tg but is far lower than Ton- The present study on the relationship between the temperature rise and the tribological performances of the liner may provide the basis for further understanding of the wear mechanisms of the liner as well as the relationship between the formation of the PTFE transfer film and the friction heat during the dry-sliding of the Finer.
基金the financial support of the National Natural Science Foundation of China(grant number 22005145)the Natural Science Foundation of Jiangsu Province(grant number BK20180495,BK20180698)+1 种基金the Opening Project of Key Laboratory of Special Energy Materials(Nanjing University of Science and Technology)the Fundamental Research Funds for the Priority Academic Program Development of Jiangsu Higher Education Institutions(grant number 30919011404)。
文摘Hydroxyl-terminated polybutadiene/toluene diisocyanate(HTPB/TDI)system is widely used in composite solid propellants.The migrations of plasticizers and water molecules from solid propellants and surrounding environment to the inhibitor have always been the important issues.This study focuses on the preparation,characterization and anti-migration behavior of graphene oxide(GO)/HTPB nanocomposite liner.The GO/HTPB(GH)composite liners affect the migration of small molecules through a tighter cross-linked structure and weakening function of small molecule adsorption.The anti-migration performance of the liner at different temperatures was analyzed,and the influence of the added amount of GO on the anti-migration performance and adhesion performance was also systematically studied.The overall performance of the liner is optimized when the amount of GO filler is 0.3 wt%.After adding 0.3 wt%GO,the concentration of dioctyl sebacate(DOS)migrated into the liner is decreased by 23.28%,and the concentration of water molecules is decreased by 51.89%,indicating that the introduction of GO can significantly improve the anti-migration performance of the liner.In addition,the bond strength is greatly increased from 0.25 MPa to 0.95 MPa,which meets the application requirements of the current propellant system.This research provides an important way for the preparation of structure-function synergistic anti-migration composite liners.
