Purpose–Type-120 relief valves are critical components of locomotive braking systems,and they rapidly discharge the air pressure during brake release to enable swift pressure relief.In order to develop type-120 relie...Purpose–Type-120 relief valves are critical components of locomotive braking systems,and they rapidly discharge the air pressure during brake release to enable swift pressure relief.In order to develop type-120 relief valve rubber diaphragms with long life and high performance,the damaged faulty samples were analyzed and studied.Design/methodology/approach–Finite element analysis(FEA)was used to investigate the stress distribution and failure mechanism of the rubber diaphragms within the type-120 relief valves under dynamic loading conditions.The Ogden hyperelastic constitutive model was used to fit the diaphragm data obtained from the uniaxial tensile tests,and its suitability for the modeling of large deformations was confirmed.Findings–The FEA results indicated that,when the rubber diaphragms reached their maximum deformation,the peak stress on their upper surfaces was 5.44 MPa.Thus,this region is highly susceptible to fatigue damage.The service life of the rubber diaphragms could be extended by using rubber compounds with high tensile moduli or a fabric-reinforced rubber diaphragm.Originality/value–This study provides valuable data and experience for the development of the rubber diaphragms in the type-120 valves and other long-life rubber products in the railway field.展开更多
Serving as the initiating explosive devices between the propellant tank and the engines,metal-based rupture diaphragms are widely used in ramjet igniters owing to the advantages provided by their simple structure,smal...Serving as the initiating explosive devices between the propellant tank and the engines,metal-based rupture diaphragms are widely used in ramjet igniters owing to the advantages provided by their simple structure,small size,and low cost.However,the reliability of rupture pressure directly affects the success of engine ignition and rocket launch,which is mainly influenced by factors like material,structure,and residual thickness of the surface notch of the diaphragm.Among those,the geometry of the notch is easy to define and control when compared to the mechanical parameters of the ruptured diaphragm.Thus,to make the diaphragm rupture(1A30 Al)within the required pressure range(0.4 MPa±3.5%)with highly sensitive and reliability,we draw inspiration from the arthropod’s force-sensitive slit organ which encompasses curved microgrooves to design a Ω-shaped notch for the rupture diaphragm.Finite element analysis is used to study the relationship between the burst pressure and geometric dimension of theΩ-shaped and bioinspired microgroove.Based on that,metal-based rupture diaphragms are fabricated by femtosecond laser processing technology,followed by rupture tests.Experiment results demonstrate that the practical rupture pressure of the diaphragm is highly consistent with the finite element analysis results,which verifies the effectiveness of the bionic design.展开更多
Diaphragms are essential structural elements of the earthquake-resisting system in a building.Diaphragms are the building slabs subjected to in-plane forces which are transferred to the vertical elements of the earthq...Diaphragms are essential structural elements of the earthquake-resisting system in a building.Diaphragms are the building slabs subjected to in-plane forces which are transferred to the vertical elements of the earthquakeresisting system.In-plane forces can arise from inertial loads and from self-equilibrating forces caused by the interaction between elements of the vertical earthquake-resisting system of different stiffness.The analysis and design of diaphragms is one of the most challenging tasks in design of buildings nowadays.This paper describes a stringer-panel model used as a macro-element for the modeling of building diaphragms in linear and nonlinear time-history analyses.The element was coded in the open-sourcefinite element software OpenSees.The linear version of the element isfirst used to support the design of diaphragms in a building.Then,the nonlinear response of the diaphragms is assessed with the nonlinear version of the element.Key response parameters of diaphragms modeled with the dynamic stringer-panel method in a high-rise building of complex geometry are presented.Results show significant redistribution of internal forces occurs through the diaphragm after cracking,leading to a general reduction of the tensile forces and an increase in the compressive forces.The clear load path,computational stability,effciency,and highly design-oriented representation of the results of this method make it an attractive alternative for its use in the modeling and design of diaphragms in performance-based seismic design.展开更多
Floor diaphragms may provide an effective solution for reducing the seismic vulnerability of masonry buildings. Unfortunately, diaphragms are usually not present in historical building with wooden floors but often the...Floor diaphragms may provide an effective solution for reducing the seismic vulnerability of masonry buildings. Unfortunately, diaphragms are usually not present in historical building with wooden floors but often they are non present even in old R/C buildings where floors were made without shear reinforcement. A possible strengthening technique could be based on the application of a thin concrete plate reintbrced with a welded mesh. In order to reduce the thickness of the plate, some suitable solutions may be obtained by using Fiber Reinforced Concrete （FRC） since the minimum concrete cover is no longer required because the reinforcement （fibers） is spread all over the concrete matrix. The adoption of FRC floor diaphragms is proposed and discussed in this paper; the early results from a preliminary numerical study are analyzed in order to asses the feasibility of this new strengthening technique and better organize an experimental program that is currently in progress.展开更多
AIM： To investigate whether NSAIDs/ASA lesions in the colon can histologically be diagnosed on the basis of ischemic necrosis similar to biopsy-based diagnosis of NSAIDs/ASA- induced erosions and ulcers of the stomac...AIM： To investigate whether NSAIDs/ASA lesions in the colon can histologically be diagnosed on the basis of ischemic necrosis similar to biopsy-based diagnosis of NSAIDs/ASA- induced erosions and ulcers of the stomach. METHODS： In the period between 1997 and 2002, we investigated biopsy materials obtained from 611 patients （415 women, 196 men, average age 60.5 years） with endoscopic focal erosions, ulcerations, strictures or diaphragms in the colon. In the biopsies obtained from these lesions, we always established the suspected diagnosis of NSA/D-inducecl lesions whenever necroses of the ischemic type were found. Together with the histological report, we enclosed a questionnaire to investigate the use of medication. The data provided by the questionnaire were then correlated with the endoscopic findings, the location, number and nature of the lesions, and the histological findings. RESULTS： At the time of their colonoscopy, 86.1% of the patients had indeed been taking NSAID/ASA medication for years （43.9%） or months （29.5%）. The most common indication for the use of these drugs was pain （64.3%）, and the most common indication for colonoscopy was bleeding （55.5%）. Endoscopic inspection revealed multiple erosions and/or ulcers in 60.6%, strictures in 15.8%, and diaphragms in 3.0% of the patients. The lesions were located mainly in the right colon including the transverse colon （79.9%）. A separate analysis of age and sex distribution, endoscopic and histological findings for NSAIDs alone, ASA alone, combined NSAID/ASA, and for patients denying the use of such drugs, revealed no significant differences among the groups. CONCLUSION： This uncontrolled retrospective study based on the histological finding of an ischemic necrosis shows that the histologically suspected diagnosis of NSAID-induced lesions in the colon is often correct. The true diagnostic validity of this finding and the differentiation from ischemic colitis should, however, be investigated in a prospective controlled study.展开更多
Purpose–The type 120 emergency valve is an essential braking component of railway freight trains,butcorresponding diaphragms consisting of natural rubber(NR)and chloroprene rubber(CR)exhibit insufficientaging resista...Purpose–The type 120 emergency valve is an essential braking component of railway freight trains,butcorresponding diaphragms consisting of natural rubber(NR)and chloroprene rubber(CR)exhibit insufficientaging resistance and low-temperature resistance,respectively.In order to develop type 120 emergency valverubber diaphragms with long-life and high-performance,low-temperatureresistant CR and NR were processed.Design/methodology/approach–The physical properties of the low-temperature-resistant CR and NRwere tested by low-temperature stretching,dynamic mechanical analysis,differential scanning calorimetryand thermogravimetric analysis.Single-valve and single-vehicle tests of type 120 emergency valves werecarried out for emergency diaphragms consisting of NR and CR.Findings–The low-temperature-resistant CR and NR exhibited excellent physical properties.The elasticityand low-temperature resistance of NR were superior to those of CR,whereas the mechanical properties of thetwo rubbers were similar in the temperature range of 0℃–150℃.The NR and CR emergency diaphragms metthe requirements of the single-valve test.In the low-temperature single-vehicle test,only the low-temperaturesensitivity test of the NR emergency diaphragm met the requirements.Originality/value–The innovation of this study is that it provides valuable data and experience for futuredevelopment of type 120 valve rubber diaphragms.展开更多
A numerical study of bitubular tubes with diaphragms compared with single and bitubular tubes subjected to dynamic axial impact force was presented. At first, the energy absorption response of the composite structure ...A numerical study of bitubular tubes with diaphragms compared with single and bitubular tubes subjected to dynamic axial impact force was presented. At first, the energy absorption response of the composite structure under axial loading was analyzed by finite element simulation. The results show that the efficiency of energy absorption can be improved by introducing diaphragms to the double-walled columns. Then, the effect of the amount and location of diaphragms, the shape and the size of the inner tubes, and the thickness of the composite structures were also studied numerically. The collision performance of the composite structure is affected by the deformation of diaphragms, as well as the interaction of outer and inner tube. The non-uniform distribution of diaphragms can improve the energy absorption efficiency of structures for a constant number of diaphragms. The specific energy absorption of the hexagonal inner tube is the highest, followed by the circular, octagonal and square ones.展开更多
In the AASHTO Guide Specifications for Seismic Bridge Design Provisions,ductile diaphragms are identified as Permissible Earthquake-Resisting Elements（EREs）,designed to help resist seismic loads applied in the trans...In the AASHTO Guide Specifications for Seismic Bridge Design Provisions,ductile diaphragms are identified as Permissible Earthquake-Resisting Elements（EREs）,designed to help resist seismic loads applied in the transverse direction of bridges.When adding longitudinal ductile diaphragms,a bidirectional ductile diaphragm system is created that can address seismic excitations acting along both the bridge’s longitudinal and transverse axes.This paper investigates bidirectional ductile diaphragms with Buckling Restrained Braces（BRBs）in straight multi-span bridge with simply supported floating spans.The flexibility of the substructures in the transverse and longitudinal direction of the bridge is considered.Design procedures for the bidirectional ductile diaphragms are first proposed.An analytical model of the example bridge with bidirectional ductile diaphragms,designed based on the proposed methodology,is then built in SAP2000.Pushover and nonlinear time history analyses are performed on the bridge model,and corresponding results are presented.The effect of changing the longitudinal stiffness of the bidirectional ductile diaphragms in the end spans connecting to the abutment is also investigated,in order to better understand the impact on the bridge’s dynamic performance.展开更多
This paper deals with the deformations, stresses and stability of circular corrugateddiaphragm under a concentrated load at the center on the basis of the large-deflection theoryof shallow shells of revolution. By usi...This paper deals with the deformations, stresses and stability of circular corrugateddiaphragm under a concentrated load at the center on the basis of the large-deflection theoryof shallow shells of revolution. By using the Newton-spline method the nonlinear equationsof the shell for circular corrugated diaphragm with sine-shaped shallow waves are solved.Solutions for both unbuckled and buckled states are obtained. Numerical results are yieldedby digital computer for some circular corrugated diaphragms with a given form of corrugations.展开更多
Shallow-buried thick sand strata present considerable local instability risks during diaphragm wall trenching construction.However,this critical issue has not been extensively studied,despite its serious safety conseq...Shallow-buried thick sand strata present considerable local instability risks during diaphragm wall trenching construction.However,this critical issue has not been extensively studied,despite its serious safety consequences.This paper proposes an automatic identification model for shallow-buried thick sand strata,integrating three-dimensional limit equilibrium theory with a genetic algorithm to precisely identify the most potentially dangerous local instability mass and determine its minimum safety factor.The model establishes three undetermined parameters:failure angle,upper boundary,and thickness of the local instability mass.These parameters define the search space for the local instability mass.The effectiveness of this approach was confirmed through a diaphragm wall engineering case near the Rhine River in France,where the predicted instability location closely aligned with field observations.A systematic analysis of the model indicated that the difference in slurry-groundwater levels and the friction angle are the most significant factors affecting local instability in shallow-buried thick sand strata.The model indicated that the location of the most potentially dangerous instability mass changes depending on geological conditions,and larger instability masses do not always relate to lower safety factors.Additionally,exploratory experiments revealed that support pressure losses caused by slurry infiltration significantly influence local instability calculations in sand strata.This points out the importance of considering these support pressure losses in the stability evaluations of high permeable sand strata.The results improve the evaluation of safety and the optimization of design for diaphragm wall construction in shallow-buried thick sand strata.展开更多
Objective:To investigate the predictive value of diaphragm thickening fraction(DTF)combined with cough peak expiratory flow(CPEF)on the success rate of weaning from mechanical ventilation.Methods:The clinical data of ...Objective:To investigate the predictive value of diaphragm thickening fraction(DTF)combined with cough peak expiratory flow(CPEF)on the success rate of weaning from mechanical ventilation.Methods:The clinical data of patients undergoing invasive mechanical ventilation via oral endotracheal intubation in the ICU of our hospital from January 2022 to December 2023 were studied.All patients underwent a 30-minute spontaneous breathing trial(SBT)using low-level pressure support ventilation(PSV)after meeting the clinical weaning screening criteria.Among them,150 patients who met the clinical weaning criteria were weaned from the ventilator.They were divided into a successful weaning group(n=100)and a failed weaning group(n=50)based on the weaning outcome.Clinical data,including age,gender,APACHE II score,duration of mechanical ventilation,DTF,and CPEF,were collected from 150 patients.The differences in clinical data between the two groups were compared,and the correlation between DTF,CPEF,and the success rate of weaning was analyzed.Results:There were no significant differences between the two groups in gender ratio(χ^(2)=0.884,P=0.347>0.05),age(t=0.350,P=0.727>0.05),and APACHE II score(t=1.295,P=0.197>0.05),but there was a significant difference in the duration of mechanical ventilation(t=3.766,P<0.001).The DTF and CPEF values in the successful weaning group were significantly higher than those in the failed weaning group(P<0.05).ROC curves were drawn to predict the weaning results using DTF,CPEF,and the combination of DTF and CPEF.The results showed that the specificity of the combination of DTF and CPEF was comparable to that of either metric alone,but the sensitivity and AUC were significantly higher than those of either metric alone.Conclusion:The combination of DTF and CPEF can be used as an effective indicator to evaluate the weaning efficacy of mechanically ventilated patients,which has important clinical significance for guiding clinical weaning treatment,improving the success rate of weaning,reducing the incidence of ventilator-associated pneumonia,and shortening the length of hospital stay.展开更多
To meticulously dissect the cracking issue in the transverse diaphragm concrete,situated at the anchor point of a colossal large-span,single cable plane cable-stayed bridge,this research paper adopts an innovative lay...To meticulously dissect the cracking issue in the transverse diaphragm concrete,situated at the anchor point of a colossal large-span,single cable plane cable-stayed bridge,this research paper adopts an innovative layered modeling analysis methodology for numerical simulations.The approach is structured into three distinct layers,each tailored to address specific aspects of the cracking phenomenon.The foundational first layer model operates under the assumption of linear elasticity,adhering to the Saint Venant principle.It narrows its focus to the crucial zone between the Bp20 transverse diaphragm and the central axis of pier 4’s support,encompassing the critically cracked diaphragm beneath the N1 cable anchor.This layer provides a preliminary estimate of potential cracking zones within the concrete,serving as a baseline for further analysis.The second layer model builds upon this foundation by incorporating material plasticity into its considerations.It pinpoints its investigation to the immediate vicinity of the cracked transverse diaphragm associated with the N1 cable,aiming to capture the intricate material behavior under stress.This layer’s predictions of crack locations and patterns exhibit a remarkable alignment with actual detection results,confirming its precision and reliability.The third and most intricate layer delves deep into the heart of the matter,examining the cracked transverse diaphragm precisely where the cable force attains its maximum intensity.By leveraging advanced extended finite element technology,this layer offers an unprecedented level of detail in tracing the progression of concrete cracks.Its findings reveal a close correlation between predicted and observed crack widths,validating the model’s proficiency in simulating real-world cracking dynamics.Crucially,the boundary conditions for each layer are meticulously aligned with those of the overarching model,ensuring consistency and integrity throughout the analysis.These results not only enrich our understanding of the cracking mechanisms but also underscore the efficacy of reinforcing cracked concrete sections with external steel plates.In conclusion,this study represents a significant contribution to the field of bridge engineering,offering both theoretical insights and practical solutions for addressing similar challenges.展开更多
The autonomous and controllable Dual Synthetic Jet Actuator(DSJA)is firstly integrated into the Unmanned Aerial Vehicle(UAV),and flight tests without the deflection of rudders are carried out to verify the viability o...The autonomous and controllable Dual Synthetic Jet Actuator(DSJA)is firstly integrated into the Unmanned Aerial Vehicle(UAV),and flight tests without the deflection of rudders are carried out to verify the viability of DSJA to control the attitudes of UAV during cruising.DSJA is improved into an actuator with two diaphragms and three cavities,which has higher energy levels.Actuators,differentially distributed on both sides of the wings,are installed on the trailing edge close to the wing tips.Flight tests,containing Differential Circulation Control(DCC)using double-side actuators,Positive Circulation Control(PCC)using left-side actuators and Negative Circulation Control(NCC)using right-side actuators,are implemented at cruising speed of 25 m/s.Results show that roll attitude control without rudders could be realized by DSJAs.DCC and NCC can generate the rightward roll and yaw angular velocity,prompting UAV to turn right.The stronger controlling ability can be achieved by DCC,with the maximum roll angular velocity of 15.62(°)/s.PCC can generate a rightward roll moment,but a leftward yaw moment will be produced at the same time.Leftward yaw induces the leftward rolling moment,which weakens the roll control effect,making UAV keep to yaw to the left with a small slope.展开更多
In recent years,lithium-sulfur batteries(LSBs)are considered as one of the most promising new generation energies with the advantages of high theoretical speeific capacity of sulfur(1675 mAh·g^(-1)),abundant sulf...In recent years,lithium-sulfur batteries(LSBs)are considered as one of the most promising new generation energies with the advantages of high theoretical speeific capacity of sulfur(1675 mAh·g^(-1)),abundant sulfur resources,and environmental friendliness storage technologies,and they are receiving wide attention from the industry.However,the problems of the shuttle effect and lithium dendrite growth in LSBs have limited their practical application,so there is a need to find ways to solve these problems.It is an excellent choice to use novel materials to modify battery materials.Among those novel materials,the metal-organic framework(MOF)has the properties of regular pores and controllable structure.When applied as a positive electrode and diaphragm,it can restrain the shuttle effect and lithium dendrite growth,especially since it shows excellent performance in diaphragm modification.Therefore,various design strategies and synthesis methods of MOF-modified separators are reviewed in this paper,and the applications of MOF in LSBs separators in different forms are introduced,including the composite of MOF and carbon-based materials,the compounding of MOF and polymer,self-carbonization to form MOF-derived materials.At the same time,different characterization techniques are systematically reviewed to obtain the physical and chemical properties of MOF particles and the working mechanism of MOF-modified diaphragm,which provides a basis for further research in this field.Finally,some future research trends and directions are put forward to fully tap the future commercial potential of MOF-modified diaphragm in LSBs.展开更多
With respect to an arbitrary configuration of a deformed structure, two sets of incremental equations are proposed for the deformation analysis of revolution shells and diaphragms loaded by both lateral pressures and ...With respect to an arbitrary configuration of a deformed structure, two sets of incremental equations are proposed for the deformation analysis of revolution shells and diaphragms loaded by both lateral pressures and the initial stresses produced in manufacturing. These general equations can be reduced to the simplified Koiter＇s Reissner-Meissner-Reissner （RMR） equations and the simplified Reissner＇s equations, when the initial stresses are set to zero. They can also be deduced to the total Lagrange form or the updated Lagrange form, respectively, as the structure is spec- ified as the un-deformed or the former-deformed configurations. These incremental equations can be easily transformed into finite difference forms and solved by common numerical solvers of ordinary differential equations. Some numerical examples are presented to show the applications of the incremental equations to the deep shell of revolution and the corrugated diaphragms used in microelectronical mechanical system （MEMS）. The results are in good agreement with those from finite element method （FEM）.展开更多
AIM: To compare safety and therapeutic efficacy of laparoscopic radiofrequency(RF) ablation vs computed tomography(CT)-guided RF ablation for large hepatic hemangiomas abutting the diaphragm.METHODS: We retrospectivel...AIM: To compare safety and therapeutic efficacy of laparoscopic radiofrequency(RF) ablation vs computed tomography(CT)-guided RF ablation for large hepatic hemangiomas abutting the diaphragm.METHODS: We retrospectively reviewed our sequential experience of treating 51 large hepatic hemangiomas abutting the diaphragm in 51 patients by CT-guided or laparoscopic RF ablation due to either the presence of symptoms and/or the enlargement of hemangioma.Altogether, 24 hemangiomas were ablated via a CTguided percutaneous approach(CT-guided ablation group), and 27 hemangiomas were treated via a laparoscopic approach(laparoscopic ablation group).RESULTS: The mean diameter of the 51 hemangiomas was 9.6 ± 1.8 cm(range, 6.0-12.0 cm). There was nodifference in the diameter of hemangiomas between the two groups(P > 0.05). RF ablation was performed successfully in all patients. There was no difference in ablation times between groups(P > 0.05). There were 23 thoracic complications in 17 patients: 15(62.5%, 15/24) in the CT-guided ablation group and2(7.4%, 2/27) in the laparoscopic ablation group(P< 0.05). According to the Dindo-Clavien classification,two complications(pleural effusion and diaphragmatic rupture grade Ⅲ) were major in two patients. All others were minor(grade Ⅰ). Both major complications occurred in the CT-guided ablation group. The minor complications were treated successfully with conservative measures, and the two major complications underwent treatment by chest tube drainage and thoracoscopic surgery, respectively. Complete ablation was achieved in 91.7%(22/24) and 96.3%(26/27) in the CT-guided and the laparoscopic ablation groups,respectively(P > 0.05).CONCLUSION: Laparoscopic RF ablation therapy should be used as the first-line treatment option for large hepatic hemangiomas abutting the diaphragm.It avoids thermal injury to the diaphragm and reduces thoracic complications.展开更多
A 2D and 3D kinematically admissible rotational failure mechanism is presented for homogeneous slurry trenches in frictional/cohesive soils.Analytical approaches are derived to obtain the upper bounds on slurry trench...A 2D and 3D kinematically admissible rotational failure mechanism is presented for homogeneous slurry trenches in frictional/cohesive soils.Analytical approaches are derived to obtain the upper bounds on slurry trench stability in the strict framework of limit analysis.It is shown that the factor of safety from a 3D analysis will be greater than that from a 2D analysis.Compared with the limit equilibrium method,the limit analysis method yields an unconservative estimate on the safety factors.A set of examples are presented in a wide range of parameters for 2D and 3D homogeneous slurry trenches.The factor of safety increases with increasing slurry and soil bulk density ratio,cohesion,friction angle,and with decreasing slurry level depth and trench depth ratio,trench width and depth ratio.It is convenient to assess the safety for the homogeneous slurry trenches in practical applications.展开更多
Construction of diaphragm wall panels may cause considerable stress changes in heavily overconsol- idated soil deposits and can induce substantial ground movement. The 3D Lagrangian method was adopted to model the mec...Construction of diaphragm wall panels may cause considerable stress changes in heavily overconsol- idated soil deposits and can induce substantial ground movement. The 3D Lagrangian method was adopted to model the mechanical response of ground, including horizontal normal stress and shear stress, lateral ground displacement and vertical ground surface settlement, during the slurry trenching and concreting of diaphragm wall panels. Numerical results show that slurry trenching leads to horizontal stress relief of ground, reducing the horizontal stress of the ground from initial K0 pressure to hydrostatic betonite pressure. Wet concrete pressure lies between the hydrostatic bentonite pressure and the initial K0 pressure, so it can compensate partially the horizontal stress loss of the ground adjacent to the trench and thus reduce the lateral movement of the trench face as well as the vertical settlement of the ground surface.展开更多
基金supported by the Science and Technology Research and Development Plan of the China State Railway Group Company Limited(Grant No.N2023J053).
文摘Purpose–Type-120 relief valves are critical components of locomotive braking systems,and they rapidly discharge the air pressure during brake release to enable swift pressure relief.In order to develop type-120 relief valve rubber diaphragms with long life and high performance,the damaged faulty samples were analyzed and studied.Design/methodology/approach–Finite element analysis(FEA)was used to investigate the stress distribution and failure mechanism of the rubber diaphragms within the type-120 relief valves under dynamic loading conditions.The Ogden hyperelastic constitutive model was used to fit the diaphragm data obtained from the uniaxial tensile tests,and its suitability for the modeling of large deformations was confirmed.Findings–The FEA results indicated that,when the rubber diaphragms reached their maximum deformation,the peak stress on their upper surfaces was 5.44 MPa.Thus,this region is highly susceptible to fatigue damage.The service life of the rubber diaphragms could be extended by using rubber compounds with high tensile moduli or a fabric-reinforced rubber diaphragm.Originality/value–This study provides valuable data and experience for the development of the rubber diaphragms in the type-120 valves and other long-life rubber products in the railway field.
基金supported by the National Key R&D Program of China(Grant No.2022YFB4601700).
文摘Serving as the initiating explosive devices between the propellant tank and the engines,metal-based rupture diaphragms are widely used in ramjet igniters owing to the advantages provided by their simple structure,small size,and low cost.However,the reliability of rupture pressure directly affects the success of engine ignition and rocket launch,which is mainly influenced by factors like material,structure,and residual thickness of the surface notch of the diaphragm.Among those,the geometry of the notch is easy to define and control when compared to the mechanical parameters of the ruptured diaphragm.Thus,to make the diaphragm rupture(1A30 Al)within the required pressure range(0.4 MPa±3.5%)with highly sensitive and reliability,we draw inspiration from the arthropod’s force-sensitive slit organ which encompasses curved microgrooves to design a Ω-shaped notch for the rupture diaphragm.Finite element analysis is used to study the relationship between the burst pressure and geometric dimension of theΩ-shaped and bioinspired microgroove.Based on that,metal-based rupture diaphragms are fabricated by femtosecond laser processing technology,followed by rupture tests.Experiment results demonstrate that the practical rupture pressure of the diaphragm is highly consistent with the finite element analysis results,which verifies the effectiveness of the bionic design.
基金the constructive comments from the anonymous reviewers.Thefirst author would like to gratefully acknowledge thefinancial support provided by Consejo Nacional de Ciencia y Tecnología(CONACYT),the UC Institute for Mexico and the United States(UC MEXUS)and the program Becas Fulbright-García Robles(COMEXUS).
文摘Diaphragms are essential structural elements of the earthquake-resisting system in a building.Diaphragms are the building slabs subjected to in-plane forces which are transferred to the vertical elements of the earthquakeresisting system.In-plane forces can arise from inertial loads and from self-equilibrating forces caused by the interaction between elements of the vertical earthquake-resisting system of different stiffness.The analysis and design of diaphragms is one of the most challenging tasks in design of buildings nowadays.This paper describes a stringer-panel model used as a macro-element for the modeling of building diaphragms in linear and nonlinear time-history analyses.The element was coded in the open-sourcefinite element software OpenSees.The linear version of the element isfirst used to support the design of diaphragms in a building.Then,the nonlinear response of the diaphragms is assessed with the nonlinear version of the element.Key response parameters of diaphragms modeled with the dynamic stringer-panel method in a high-rise building of complex geometry are presented.Results show significant redistribution of internal forces occurs through the diaphragm after cracking,leading to a general reduction of the tensile forces and an increase in the compressive forces.The clear load path,computational stability,effciency,and highly design-oriented representation of the results of this method make it an attractive alternative for its use in the modeling and design of diaphragms in performance-based seismic design.
文摘Floor diaphragms may provide an effective solution for reducing the seismic vulnerability of masonry buildings. Unfortunately, diaphragms are usually not present in historical building with wooden floors but often they are non present even in old R/C buildings where floors were made without shear reinforcement. A possible strengthening technique could be based on the application of a thin concrete plate reintbrced with a welded mesh. In order to reduce the thickness of the plate, some suitable solutions may be obtained by using Fiber Reinforced Concrete （FRC） since the minimum concrete cover is no longer required because the reinforcement （fibers） is spread all over the concrete matrix. The adoption of FRC floor diaphragms is proposed and discussed in this paper; the early results from a preliminary numerical study are analyzed in order to asses the feasibility of this new strengthening technique and better organize an experimental program that is currently in progress.
文摘AIM： To investigate whether NSAIDs/ASA lesions in the colon can histologically be diagnosed on the basis of ischemic necrosis similar to biopsy-based diagnosis of NSAIDs/ASA- induced erosions and ulcers of the stomach. METHODS： In the period between 1997 and 2002, we investigated biopsy materials obtained from 611 patients （415 women, 196 men, average age 60.5 years） with endoscopic focal erosions, ulcerations, strictures or diaphragms in the colon. In the biopsies obtained from these lesions, we always established the suspected diagnosis of NSA/D-inducecl lesions whenever necroses of the ischemic type were found. Together with the histological report, we enclosed a questionnaire to investigate the use of medication. The data provided by the questionnaire were then correlated with the endoscopic findings, the location, number and nature of the lesions, and the histological findings. RESULTS： At the time of their colonoscopy, 86.1% of the patients had indeed been taking NSAID/ASA medication for years （43.9%） or months （29.5%）. The most common indication for the use of these drugs was pain （64.3%）, and the most common indication for colonoscopy was bleeding （55.5%）. Endoscopic inspection revealed multiple erosions and/or ulcers in 60.6%, strictures in 15.8%, and diaphragms in 3.0% of the patients. The lesions were located mainly in the right colon including the transverse colon （79.9%）. A separate analysis of age and sex distribution, endoscopic and histological findings for NSAIDs alone, ASA alone, combined NSAID/ASA, and for patients denying the use of such drugs, revealed no significant differences among the groups. CONCLUSION： This uncontrolled retrospective study based on the histological finding of an ischemic necrosis shows that the histologically suspected diagnosis of NSAID-induced lesions in the colon is often correct. The true diagnostic validity of this finding and the differentiation from ischemic colitis should, however, be investigated in a prospective controlled study.
基金funded by the Science and Technology Research and Development Plan of the China State Railway Group Company Limited(No.N2023J053).
文摘Purpose–The type 120 emergency valve is an essential braking component of railway freight trains,butcorresponding diaphragms consisting of natural rubber(NR)and chloroprene rubber(CR)exhibit insufficientaging resistance and low-temperature resistance,respectively.In order to develop type 120 emergency valverubber diaphragms with long-life and high-performance,low-temperatureresistant CR and NR were processed.Design/methodology/approach–The physical properties of the low-temperature-resistant CR and NRwere tested by low-temperature stretching,dynamic mechanical analysis,differential scanning calorimetryand thermogravimetric analysis.Single-valve and single-vehicle tests of type 120 emergency valves werecarried out for emergency diaphragms consisting of NR and CR.Findings–The low-temperature-resistant CR and NR exhibited excellent physical properties.The elasticityand low-temperature resistance of NR were superior to those of CR,whereas the mechanical properties of thetwo rubbers were similar in the temperature range of 0℃–150℃.The NR and CR emergency diaphragms metthe requirements of the single-valve test.In the low-temperature single-vehicle test,only the low-temperaturesensitivity test of the NR emergency diaphragm met the requirements.Originality/value–The innovation of this study is that it provides valuable data and experience for futuredevelopment of type 120 valve rubber diaphragms.
基金Projects(U1334208,51405516,51275532) supported by the National Natural Science Foundation of ChinaProject(2015ZZTS045) supported by the Fundamental Research Funds for the Central Universities of China
文摘A numerical study of bitubular tubes with diaphragms compared with single and bitubular tubes subjected to dynamic axial impact force was presented. At first, the energy absorption response of the composite structure under axial loading was analyzed by finite element simulation. The results show that the efficiency of energy absorption can be improved by introducing diaphragms to the double-walled columns. Then, the effect of the amount and location of diaphragms, the shape and the size of the inner tubes, and the thickness of the composite structures were also studied numerically. The collision performance of the composite structure is affected by the deformation of diaphragms, as well as the interaction of outer and inner tube. The non-uniform distribution of diaphragms can improve the energy absorption efficiency of structures for a constant number of diaphragms. The specific energy absorption of the hexagonal inner tube is the highest, followed by the circular, octagonal and square ones.
文摘In the AASHTO Guide Specifications for Seismic Bridge Design Provisions,ductile diaphragms are identified as Permissible Earthquake-Resisting Elements（EREs）,designed to help resist seismic loads applied in the transverse direction of bridges.When adding longitudinal ductile diaphragms,a bidirectional ductile diaphragm system is created that can address seismic excitations acting along both the bridge’s longitudinal and transverse axes.This paper investigates bidirectional ductile diaphragms with Buckling Restrained Braces（BRBs）in straight multi-span bridge with simply supported floating spans.The flexibility of the substructures in the transverse and longitudinal direction of the bridge is considered.Design procedures for the bidirectional ductile diaphragms are first proposed.An analytical model of the example bridge with bidirectional ductile diaphragms,designed based on the proposed methodology,is then built in SAP2000.Pushover and nonlinear time history analyses are performed on the bridge model,and corresponding results are presented.The effect of changing the longitudinal stiffness of the bidirectional ductile diaphragms in the end spans connecting to the abutment is also investigated,in order to better understand the impact on the bridge’s dynamic performance.
基金Projiect supported by the National Natural Science Foundation of China.
文摘This paper deals with the deformations, stresses and stability of circular corrugateddiaphragm under a concentrated load at the center on the basis of the large-deflection theoryof shallow shells of revolution. By using the Newton-spline method the nonlinear equationsof the shell for circular corrugated diaphragm with sine-shaped shallow waves are solved.Solutions for both unbuckled and buckled states are obtained. Numerical results are yieldedby digital computer for some circular corrugated diaphragms with a given form of corrugations.
基金supported by the Fundamental Research Funds for the Central Universities(No.02302350113).
文摘Shallow-buried thick sand strata present considerable local instability risks during diaphragm wall trenching construction.However,this critical issue has not been extensively studied,despite its serious safety consequences.This paper proposes an automatic identification model for shallow-buried thick sand strata,integrating three-dimensional limit equilibrium theory with a genetic algorithm to precisely identify the most potentially dangerous local instability mass and determine its minimum safety factor.The model establishes three undetermined parameters:failure angle,upper boundary,and thickness of the local instability mass.These parameters define the search space for the local instability mass.The effectiveness of this approach was confirmed through a diaphragm wall engineering case near the Rhine River in France,where the predicted instability location closely aligned with field observations.A systematic analysis of the model indicated that the difference in slurry-groundwater levels and the friction angle are the most significant factors affecting local instability in shallow-buried thick sand strata.The model indicated that the location of the most potentially dangerous instability mass changes depending on geological conditions,and larger instability masses do not always relate to lower safety factors.Additionally,exploratory experiments revealed that support pressure losses caused by slurry infiltration significantly influence local instability calculations in sand strata.This points out the importance of considering these support pressure losses in the stability evaluations of high permeable sand strata.The results improve the evaluation of safety and the optimization of design for diaphragm wall construction in shallow-buried thick sand strata.
文摘Objective:To investigate the predictive value of diaphragm thickening fraction(DTF)combined with cough peak expiratory flow(CPEF)on the success rate of weaning from mechanical ventilation.Methods:The clinical data of patients undergoing invasive mechanical ventilation via oral endotracheal intubation in the ICU of our hospital from January 2022 to December 2023 were studied.All patients underwent a 30-minute spontaneous breathing trial(SBT)using low-level pressure support ventilation(PSV)after meeting the clinical weaning screening criteria.Among them,150 patients who met the clinical weaning criteria were weaned from the ventilator.They were divided into a successful weaning group(n=100)and a failed weaning group(n=50)based on the weaning outcome.Clinical data,including age,gender,APACHE II score,duration of mechanical ventilation,DTF,and CPEF,were collected from 150 patients.The differences in clinical data between the two groups were compared,and the correlation between DTF,CPEF,and the success rate of weaning was analyzed.Results:There were no significant differences between the two groups in gender ratio(χ^(2)=0.884,P=0.347>0.05),age(t=0.350,P=0.727>0.05),and APACHE II score(t=1.295,P=0.197>0.05),but there was a significant difference in the duration of mechanical ventilation(t=3.766,P<0.001).The DTF and CPEF values in the successful weaning group were significantly higher than those in the failed weaning group(P<0.05).ROC curves were drawn to predict the weaning results using DTF,CPEF,and the combination of DTF and CPEF.The results showed that the specificity of the combination of DTF and CPEF was comparable to that of either metric alone,but the sensitivity and AUC were significantly higher than those of either metric alone.Conclusion:The combination of DTF and CPEF can be used as an effective indicator to evaluate the weaning efficacy of mechanically ventilated patients,which has important clinical significance for guiding clinical weaning treatment,improving the success rate of weaning,reducing the incidence of ventilator-associated pneumonia,and shortening the length of hospital stay.
基金financially supported by National Natural Science Foundation of China(Project No.51878156,received by Wenwei Wang).
文摘To meticulously dissect the cracking issue in the transverse diaphragm concrete,situated at the anchor point of a colossal large-span,single cable plane cable-stayed bridge,this research paper adopts an innovative layered modeling analysis methodology for numerical simulations.The approach is structured into three distinct layers,each tailored to address specific aspects of the cracking phenomenon.The foundational first layer model operates under the assumption of linear elasticity,adhering to the Saint Venant principle.It narrows its focus to the crucial zone between the Bp20 transverse diaphragm and the central axis of pier 4’s support,encompassing the critically cracked diaphragm beneath the N1 cable anchor.This layer provides a preliminary estimate of potential cracking zones within the concrete,serving as a baseline for further analysis.The second layer model builds upon this foundation by incorporating material plasticity into its considerations.It pinpoints its investigation to the immediate vicinity of the cracked transverse diaphragm associated with the N1 cable,aiming to capture the intricate material behavior under stress.This layer’s predictions of crack locations and patterns exhibit a remarkable alignment with actual detection results,confirming its precision and reliability.The third and most intricate layer delves deep into the heart of the matter,examining the cracked transverse diaphragm precisely where the cable force attains its maximum intensity.By leveraging advanced extended finite element technology,this layer offers an unprecedented level of detail in tracing the progression of concrete cracks.Its findings reveal a close correlation between predicted and observed crack widths,validating the model’s proficiency in simulating real-world cracking dynamics.Crucially,the boundary conditions for each layer are meticulously aligned with those of the overarching model,ensuring consistency and integrity throughout the analysis.These results not only enrich our understanding of the cracking mechanisms but also underscore the efficacy of reinforcing cracked concrete sections with external steel plates.In conclusion,this study represents a significant contribution to the field of bridge engineering,offering both theoretical insights and practical solutions for addressing similar challenges.
基金co-supported by the National Natural Science Foundation of China(Nos.11972369,11872374)the Youth Science and Technology Innovation Award Funded Project of National University of Defense Technology,China(No.434517314)。
文摘The autonomous and controllable Dual Synthetic Jet Actuator(DSJA)is firstly integrated into the Unmanned Aerial Vehicle(UAV),and flight tests without the deflection of rudders are carried out to verify the viability of DSJA to control the attitudes of UAV during cruising.DSJA is improved into an actuator with two diaphragms and three cavities,which has higher energy levels.Actuators,differentially distributed on both sides of the wings,are installed on the trailing edge close to the wing tips.Flight tests,containing Differential Circulation Control(DCC)using double-side actuators,Positive Circulation Control(PCC)using left-side actuators and Negative Circulation Control(NCC)using right-side actuators,are implemented at cruising speed of 25 m/s.Results show that roll attitude control without rudders could be realized by DSJAs.DCC and NCC can generate the rightward roll and yaw angular velocity,prompting UAV to turn right.The stronger controlling ability can be achieved by DCC,with the maximum roll angular velocity of 15.62(°)/s.PCC can generate a rightward roll moment,but a leftward yaw moment will be produced at the same time.Leftward yaw induces the leftward rolling moment,which weakens the roll control effect,making UAV keep to yaw to the left with a small slope.
基金financially supported by the Natural Science Foundation of Yunnan Province(No.202101AW070006)the Basic Research Plan(Key Project)of Yunnan Province(No.202101BE070001-018)+1 种基金Yunnan Major Scientific and Technological Projects(No.202202AG050003)the Key Research and Development Program of Yunnan Province(No.202103AA080019)。
文摘In recent years,lithium-sulfur batteries(LSBs)are considered as one of the most promising new generation energies with the advantages of high theoretical speeific capacity of sulfur(1675 mAh·g^(-1)),abundant sulfur resources,and environmental friendliness storage technologies,and they are receiving wide attention from the industry.However,the problems of the shuttle effect and lithium dendrite growth in LSBs have limited their practical application,so there is a need to find ways to solve these problems.It is an excellent choice to use novel materials to modify battery materials.Among those novel materials,the metal-organic framework(MOF)has the properties of regular pores and controllable structure.When applied as a positive electrode and diaphragm,it can restrain the shuttle effect and lithium dendrite growth,especially since it shows excellent performance in diaphragm modification.Therefore,various design strategies and synthesis methods of MOF-modified separators are reviewed in this paper,and the applications of MOF in LSBs separators in different forms are introduced,including the composite of MOF and carbon-based materials,the compounding of MOF and polymer,self-carbonization to form MOF-derived materials.At the same time,different characterization techniques are systematically reviewed to obtain the physical and chemical properties of MOF particles and the working mechanism of MOF-modified diaphragm,which provides a basis for further research in this field.Finally,some future research trends and directions are put forward to fully tap the future commercial potential of MOF-modified diaphragm in LSBs.
基金supported by the National Natural Science Foundation of China(No.51268054 and No.51468061)Natural Science Foundation of Tianjin,China(No.13JCQNJC07300)
基金The project supported by the National Natural Science Foundation of China(10125211)the 973 Program(G1999033108)
文摘With respect to an arbitrary configuration of a deformed structure, two sets of incremental equations are proposed for the deformation analysis of revolution shells and diaphragms loaded by both lateral pressures and the initial stresses produced in manufacturing. These general equations can be reduced to the simplified Koiter＇s Reissner-Meissner-Reissner （RMR） equations and the simplified Reissner＇s equations, when the initial stresses are set to zero. They can also be deduced to the total Lagrange form or the updated Lagrange form, respectively, as the structure is spec- ified as the un-deformed or the former-deformed configurations. These incremental equations can be easily transformed into finite difference forms and solved by common numerical solvers of ordinary differential equations. Some numerical examples are presented to show the applications of the incremental equations to the deep shell of revolution and the corrugated diaphragms used in microelectronical mechanical system （MEMS）. The results are in good agreement with those from finite element method （FEM）.
基金Supported by the Dr.Jieping Wu Medical Foundation,No.320675007131 and No.32067501207Clinical-Basic Medicine Cooperation Fund of Capital Medical University,No.1300171711the Program for Medical Key Discipline of Shijingshan District,No.20130001
文摘AIM: To compare safety and therapeutic efficacy of laparoscopic radiofrequency(RF) ablation vs computed tomography(CT)-guided RF ablation for large hepatic hemangiomas abutting the diaphragm.METHODS: We retrospectively reviewed our sequential experience of treating 51 large hepatic hemangiomas abutting the diaphragm in 51 patients by CT-guided or laparoscopic RF ablation due to either the presence of symptoms and/or the enlargement of hemangioma.Altogether, 24 hemangiomas were ablated via a CTguided percutaneous approach(CT-guided ablation group), and 27 hemangiomas were treated via a laparoscopic approach(laparoscopic ablation group).RESULTS: The mean diameter of the 51 hemangiomas was 9.6 ± 1.8 cm(range, 6.0-12.0 cm). There was nodifference in the diameter of hemangiomas between the two groups(P > 0.05). RF ablation was performed successfully in all patients. There was no difference in ablation times between groups(P > 0.05). There were 23 thoracic complications in 17 patients: 15(62.5%, 15/24) in the CT-guided ablation group and2(7.4%, 2/27) in the laparoscopic ablation group(P< 0.05). According to the Dindo-Clavien classification,two complications(pleural effusion and diaphragmatic rupture grade Ⅲ) were major in two patients. All others were minor(grade Ⅰ). Both major complications occurred in the CT-guided ablation group. The minor complications were treated successfully with conservative measures, and the two major complications underwent treatment by chest tube drainage and thoracoscopic surgery, respectively. Complete ablation was achieved in 91.7%(22/24) and 96.3%(26/27) in the CT-guided and the laparoscopic ablation groups,respectively(P > 0.05).CONCLUSION: Laparoscopic RF ablation therapy should be used as the first-line treatment option for large hepatic hemangiomas abutting the diaphragm.It avoids thermal injury to the diaphragm and reduces thoracic complications.
基金Project (Nos. 41002095,41172251 and 41272317) supported by the National Natural Science Foundation of China
文摘A 2D and 3D kinematically admissible rotational failure mechanism is presented for homogeneous slurry trenches in frictional/cohesive soils.Analytical approaches are derived to obtain the upper bounds on slurry trench stability in the strict framework of limit analysis.It is shown that the factor of safety from a 3D analysis will be greater than that from a 2D analysis.Compared with the limit equilibrium method,the limit analysis method yields an unconservative estimate on the safety factors.A set of examples are presented in a wide range of parameters for 2D and 3D homogeneous slurry trenches.The factor of safety increases with increasing slurry and soil bulk density ratio,cohesion,friction angle,and with decreasing slurry level depth and trench depth ratio,trench width and depth ratio.It is convenient to assess the safety for the homogeneous slurry trenches in practical applications.
基金the National Natural Science Foundation of China (No. 50679041)the Shanghai Leading Academic Discipline Project (No. B208)
文摘Construction of diaphragm wall panels may cause considerable stress changes in heavily overconsol- idated soil deposits and can induce substantial ground movement. The 3D Lagrangian method was adopted to model the mechanical response of ground, including horizontal normal stress and shear stress, lateral ground displacement and vertical ground surface settlement, during the slurry trenching and concreting of diaphragm wall panels. Numerical results show that slurry trenching leads to horizontal stress relief of ground, reducing the horizontal stress of the ground from initial K0 pressure to hydrostatic betonite pressure. Wet concrete pressure lies between the hydrostatic bentonite pressure and the initial K0 pressure, so it can compensate partially the horizontal stress loss of the ground adjacent to the trench and thus reduce the lateral movement of the trench face as well as the vertical settlement of the ground surface.
