The present study focuses on the flow of a yield-stress(Bingham)nanofluid,consisting of suspended Fe3O4 nanoparticles,subjected to a magnetic field in a backward-facing step duct(BFS)configuration.The duct is equipped...The present study focuses on the flow of a yield-stress(Bingham)nanofluid,consisting of suspended Fe3O4 nanoparticles,subjected to a magnetic field in a backward-facing step duct(BFS)configuration.The duct is equipped with a cylindrical obstacle,where the lower wall is kept at a constant temperature.The yield-stress nanofluid enters this duct at a cold temperature with fully developed velocity.The aim of the present investigation is to explore the influence of flow velocity(Re=10 to 200),nanoparticle concentration(ϕ=0 to 0.1),magnetic field intensity(Ha=0 to 100),and its inclination angle(γ=0 to 90)and nanofluid yield stress(Bn=0 to 20)on the thermal and hydrodynamic efficiency inside the backward-facing step.The numerical results have been obtained by resolving the momentum and energy balance equations using the Galerkin finite element method.The obtained results have indicated that an increase in Reynolds number and nanoparticle volume fraction enhances heat transfer.In contrast,a significant reduction is observed with an increase in Hartmann and Bingham numbers,resulting in quasi-immobilization of the fluid under the magnetic influence and radical solidification of this type of fluid,accompanied by the suppression of the vortex zone downstream of the cylindrical obstacle.This study sheds light on the complexity of this magnetically influenced fluid,with potential implications in various engineering and materials science fields.展开更多
Upgrading of abundant cellulosic biomass to isosorbide can reduce the dependence on limited fossil resources and provide a sustainable way to produce isosorbide,utilized for polymers,medicine and health care product s...Upgrading of abundant cellulosic biomass to isosorbide can reduce the dependence on limited fossil resources and provide a sustainable way to produce isosorbide,utilized for polymers,medicine and health care product synth-esis.This review comprehensively examines the key steps and catalytic systems involved in the conversion of cel-lulose to isosorbide.Initially,the reaction pathway from cellulose to isosorbide is elucidated,emphasizing three critical steps:cellulose hydrolysis,glucose hydrogenation,and the two-step dehydration of sorbitol to produce isosorbide.Additionally,the activation energy and acidic sites during cellulose hydrolysis,the impact of metal particle size and catalyst support on hydrogenation,and the effects of catalyst acidity,pore structure,and reaction conditions on sorbitol dehydration have been thoroughly examined.Finally,the progress made in cellulose con-version to isosorbide is summarized,current challenges are highlighted,and future development trends are pro-jected in this review.展开更多
Advancements in artificial intelligence and big data technologies have led to the gradual emergence of intelligent ships,which are expected to dominate the future of maritime transportation.Supporting the navigation o...Advancements in artificial intelligence and big data technologies have led to the gradual emergence of intelligent ships,which are expected to dominate the future of maritime transportation.Supporting the navigation of intelligent ships,route planning technologies have developed many route planning algorithms that prioritize economy and safety.This paper conducts an in-depth study of algorithm efficiency for a route planning problem,proposing an intelligent ship route planning algorithm based on the adaptive step size Informed-RRT^(*).This algorithm can quickly plan a short route according to automatic obstacle avoidance and is suitable for planning the routes of intelligent ships.Results show that the adaptive step size Informed-RRT^(*) algorithm can shorten the optimal route length by approximately 13.05%while ensuring the running time of the planning algorithm and avoiding approximately 23.64%of redundant sampling nodes.The improved algorithm effectively circumvents unnecessary calculations and reduces a large amount of redundant sampling data,thus improving the efficiency of route planning.In a complex water environment,the unique adaptive step size mechanism enables this algorithm to prevent restricted search tree expansion,showing strong search ability and robustness,which is of practical significance for the development of intelligent ships.展开更多
demand for faster vessels continues to grow,various high speed vessels have been designed and constructed for military,recreational,and passenger use.Planing vessels,specifically engineered for high-speed travel,requi...demand for faster vessels continues to grow,various high speed vessels have been designed and constructed for military,recreational,and passenger use.Planing vessels,specifically engineered for high-speed travel,require optimization to improve their hydrodynamic performance and stability during design.Reducing resistance and improving longitudinal stability are key challenges in the design of high-speed vessels.Various methods are employed to overcome these challenges,with the use of a transverse step being one of the most common approaches.This study explores the effect of changing the angle of the aft-wise step and incorporates these changes into existing analytical formulas,resulting in new formulas specifically for high-speed vessels equipped with aft-wise steps.This research investigates how the angle of the transverse step affects the hydrodynamic performance and longitudinal stability of high-speed vessels.Based on the results,analytical formulas have been developed to calculate the wetted surface parameters of vessels equipped with an aft-wise transverse step.The study used experimental methods to analyze the vessel's behavior with six different aft-wise transverse step angles of 0°,9°,11°,13°,15°,and 17°at three speeds of 8,10,and 12 m/s.In the experimental tests,the hydrodynamic components of resistance,trim angle,and wetted surface of the vessel were measured.Results indicate that creating an angle in the transverse step substantially improves the hydrodynamic components and longitudinal stability of the vessel.At the optimal angle,the resistance and trim angle of the vessel were reduced by 7.8%and 12.8%,respectively,compared to the base vessel.Additionally,the existing analytical methods for calculating the wetted surface area are more accurate than similar methods.展开更多
In this paper,a fu-Newton step interior-point algorithm is proposed for solving P_(*)(k)-linear complementarity problem based on a new search direction,which is an extension of Grimes'algorithm.It is proved that t...In this paper,a fu-Newton step interior-point algorithm is proposed for solving P_(*)(k)-linear complementarity problem based on a new search direction,which is an extension of Grimes'algorithm.It is proved that the number of iterations of the algorithm is O(n^(1/2)(1+4κ)logn/ε),which matches the best known iteration bound of the interior-point method for P_(*)(k)-linear complementarity problem.Some numerical results have proved the feasibility and efficiency of the proposed algorithm.展开更多
Taking a C1x motor with a backward-facing step which can generate a typical corner vortex as a reference,a numerical methodology using large eddy simulation was established in this study.Based on this methodology,the ...Taking a C1x motor with a backward-facing step which can generate a typical corner vortex as a reference,a numerical methodology using large eddy simulation was established in this study.Based on this methodology,the position of the backward-facing step of the motor was computed and analyzed to determine a basic configuration.Two key geometrical parameters,the head cavity angle and submerged nozzle cavity height,were subsequently introduced.Their effects on the corner vortex motion and their interactions with the acoustic pressure downstream of the backward-facing step were analyzed.The phenomena of vortex acoustic coupling and characteristics of pressure oscillations were further explored.The results show that the maximum error between the simulations and experimental data on the dominant frequency of pressure oscillations is 5.23%,which indicates that the numerical methodology built in this study is highly accurate.When the step is located at less than 5/8 of the total length of the combustion chamber,vortex acoustic coupling occurs,which can increase the pressure oscillations in the motor.Both the vorticity and the scale of vortices in the downstream step increase when the head cavity angle is greater than 24°,which increases the amplitude of the pressure oscillation by maximum 63.0%.The submerged nozzle cavity mainly affects the vortices in the cavity itself rather than those in the downstream step.When the height of the cavity increases from 10 to 20 mm,the pressure oscillation amplitude under the main frequency increases by 39.1%.As this height continues to increase,the amplitude of pressure oscillations increases but the primary frequency decreases.展开更多
[Objective] The aim of this study was to extract RNA,DNA and protein from plants by using modified one step method.[Method]CTAB was used for the modifying of Biozol-based one step extraction method,which was then used...[Objective] The aim of this study was to extract RNA,DNA and protein from plants by using modified one step method.[Method]CTAB was used for the modifying of Biozol-based one step extraction method,which was then used for the isolation of RNA,DNA and protein from the roots of maize（Zea mays L.）,soybean（Glycine max L.）,alfalfa（Medicago sativa L.）and cucumber（Cucumis sativus L.）.And the heme oxygenase-1 gene（HO-1）and calcium-dependent protein kinase-1 gene（CDPK1）,as well as HO-1 protein were identified.[Result]The result of UV spectrophotometer determination and agarose gel electrophoresis analysis showed that the purity of obtained RNA and DNA sample was relatively high;HO-1 and CDPK1 gene exhibited the positive signals checked by RT-PCR;the extracted protein could be used for western blotting analysis;the whole isolation procedure cost 3 h.[Conclusion]This method can be used as a good reference for researcher and will offer a better value with a wide range of applications.展开更多
Bionic microfluidics is garnering increasing attention due to the superior fluidic performance enabled by biomimetic microstructures.Inspired by the unique structures of young pumpkin stems,we fabricate helicoidally p...Bionic microfluidics is garnering increasing attention due to the superior fluidic performance enabled by biomimetic microstructures.Inspired by the unique structures of young pumpkin stems,we fabricate helicoidally patterned microchannels with precisely controlled morphologies using the projection micro-stereolithography(PμSL)-based 3D printing technique.Our helicoidally patterned microchannels achieve approximately twice the liquid lifting height compared to similarly sized smooth microchannels.This improvement is attributed to the enhanced capillary force.The additional meniscus formed between the helicoidally patterned microstructures significantly contributes to the increased capillary effects.Furthermore,the underlying mechanisms of fluidic performance in helicoidally patterned microchannels are theorized using a newly developed equation,which is also employed to optimize the geometric parameters and fluidic performance of the biomimetic helicoidal microchannels.Additionally,our biomimetic helicoidally patterned microchannels facilitate a significant step-lifting phenomenon,mimicking tall trees'transpiration.The fluidic performance of our biomimetic helicoidally patterned microchannels show promise for applications in enhanced liquid lifting,step-lifting,clean-water production,and others.展开更多
Dear Editor,Sleep plays a vital role in physical health,influencing chronic diseases,memory,and overall quality of life[1,2].In recent years,the relationship between sleep health and physical activity has gained atten...Dear Editor,Sleep plays a vital role in physical health,influencing chronic diseases,memory,and overall quality of life[1,2].In recent years,the relationship between sleep health and physical activity has gained attention,with a particular focus on how daily step count affects various sleep metrics.展开更多
In the practical slope engineering,the stability of lower sliding mass(region A)with back tensile cracks of the jointed rock slope attracts more attentions,but the upper rock mass(region B)may also be unstable.Therefo...In the practical slope engineering,the stability of lower sliding mass(region A)with back tensile cracks of the jointed rock slope attracts more attentions,but the upper rock mass(region B)may also be unstable.Therefore,in this study,based on the stepped failure mode of bedding jointed rock slopes,considering the influence of the upper rock mass on the lower stepped sliding mass,the improved failure model for analyzing the interaction force(F_(AB))between two regions is constructed,and the safety factors(F_(S))of two regions and whole region are derived.In addition,this paper proposes a method to determine the existence of F_(AB) using their respective acceleration values(a_(A) and a_(B))when regions A and B are unstable.The influences of key parameters on two regions and the whole region are analyzed.The results show that the variation of the F_(AB) and F_(S) of two regions can be obtained accurately based on the improved failure model.The accuracy of the improved failure model is verified by comparative analysis.The research results can explain the interaction mechanism of two regions and the natural phenomenon of slope failure caused by the development of cracks.展开更多
BACKGROUND Owing to age-related physiological declines,elderly patients undergoing radical gastrectomy(RG)often experience physical and psychological challenges.Hence,appropriate nursing strategies need to be identifi...BACKGROUND Owing to age-related physiological declines,elderly patients undergoing radical gastrectomy(RG)often experience physical and psychological challenges.Hence,appropriate nursing strategies need to be identified for optimizing patient outcomes.AIM To evaluate the effects of the Neuman Systems Model-guided stepped care intervention(NGSC)model on postoperative physical and psychological recovery in elderly patients with gastric cancer who underwent RG.METHODS In total,80 elderly patients(≥65 years old)who underwent RG at the Shanxi Fenyang Hospital between January 2023 and June 2024 were included and randomly divided as follows:Control group(n=40,those receiving conventional stepped care intervention);observation group(n=40,those receiving NGSC).Postoperative recovery indices,anxiety/depression scores(Self-Rating Anxiety Scale/Self-Rating Depression Scale),quality of life(36-item short form health survey),and adverse event rates were compared between the groups.RESULTS Compared with the control group,the observation group presented significantly shorter recovery times for first bowel sounds,ambulation,flatus,oral intake,catheter removal,and hospitalization(all P<0.05).Notably,in the observation group,Self-Rating Anxiety Scale/Self-Rating Depression Scale scores and the adverse event rate were significantly lower(all P<0.05),whereas 36-item short form health survey scores were higher(P<0.05),compared with those in the control group.CONCLUSION Overall,the findings of this study show that the proposed NGSC model accelerates postoperative recovery,alleviates psychological distress,improves quality of life,and reduces complications in elderly patients with gastric cancer who underwent RG,presenting potential for clinical application.展开更多
Aim To analyze dynamic failure of aerospace strutures subjected lateral impulsive loading. Methods Structures were modeled as rigid-perfectly plastic free-free stepped beams. Basic equations of motion un set up f...Aim To analyze dynamic failure of aerospace strutures subjected lateral impulsive loading. Methods Structures were modeled as rigid-perfectly plastic free-free stepped beams. Basic equations of motion un set up for analysis. Results Final pat deformation and rigid motion solutions were determined for a uniform impulsive loading. The critical rupture conditions for a space shuttle and a missile were obtained. Conclusion Failure is possible for aerospace structures under a uniform impulsive loading, but it is mere difficult in space.展开更多
An idealized numerical wave flume has been established by finite element method on the bases of Navier Stokes equations through prescribing the appropriate boundary conditions for the open boundary,incident boundary,...An idealized numerical wave flume has been established by finite element method on the bases of Navier Stokes equations through prescribing the appropriate boundary conditions for the open boundary,incident boundary,free surface and solid boundary in this paper.The characteristics of waves propagating over a step have been investigated by this numerical model.The breaker wave height is determined depending on the kinetic criterion.The numerical model is verified by laboratory experiments,and the empirical formula for the damping of wave height due to breaking is also given by experiments.展开更多
A growing interest has been devoted to the contra-rotating propellers （CRPs） due to their high propulsive efficiency, torque balance, low fuel consumption, low cavitations, low noise performance and low hull vibrati...A growing interest has been devoted to the contra-rotating propellers （CRPs） due to their high propulsive efficiency, torque balance, low fuel consumption, low cavitations, low noise performance and low hull vibration. Compared with the single-screw system, it is more difficult for the open water performance prediction because forward and aft propellers interact with each other and generate a more complicated flow field around the CRPs system. The current work focuses on the open water performance prediction of contra-rotating propellers by RANS and sliding mesh method considering the effect of computational time step size and turbulence model. The validation study has been performed on two sets of contra-rotating propellers developed by David W Taylor Naval Ship R ＆ D center. Compared with the experimental data, it shows that RANS with sliding mesh method and SST k-ω turbulence model has a good precision in the open water performance prediction of contra-rotating propellers, and small time step size can improve the level of accuracy for CRPs with the same blade number of forward and aft propellers, while a relatively large time step size is a better choice for CRPs with different blade numbers.展开更多
文摘The present study focuses on the flow of a yield-stress(Bingham)nanofluid,consisting of suspended Fe3O4 nanoparticles,subjected to a magnetic field in a backward-facing step duct(BFS)configuration.The duct is equipped with a cylindrical obstacle,where the lower wall is kept at a constant temperature.The yield-stress nanofluid enters this duct at a cold temperature with fully developed velocity.The aim of the present investigation is to explore the influence of flow velocity(Re=10 to 200),nanoparticle concentration(ϕ=0 to 0.1),magnetic field intensity(Ha=0 to 100),and its inclination angle(γ=0 to 90)and nanofluid yield stress(Bn=0 to 20)on the thermal and hydrodynamic efficiency inside the backward-facing step.The numerical results have been obtained by resolving the momentum and energy balance equations using the Galerkin finite element method.The obtained results have indicated that an increase in Reynolds number and nanoparticle volume fraction enhances heat transfer.In contrast,a significant reduction is observed with an increase in Hartmann and Bingham numbers,resulting in quasi-immobilization of the fluid under the magnetic influence and radical solidification of this type of fluid,accompanied by the suppression of the vortex zone downstream of the cylindrical obstacle.This study sheds light on the complexity of this magnetically influenced fluid,with potential implications in various engineering and materials science fields.
文摘Upgrading of abundant cellulosic biomass to isosorbide can reduce the dependence on limited fossil resources and provide a sustainable way to produce isosorbide,utilized for polymers,medicine and health care product synth-esis.This review comprehensively examines the key steps and catalytic systems involved in the conversion of cel-lulose to isosorbide.Initially,the reaction pathway from cellulose to isosorbide is elucidated,emphasizing three critical steps:cellulose hydrolysis,glucose hydrogenation,and the two-step dehydration of sorbitol to produce isosorbide.Additionally,the activation energy and acidic sites during cellulose hydrolysis,the impact of metal particle size and catalyst support on hydrogenation,and the effects of catalyst acidity,pore structure,and reaction conditions on sorbitol dehydration have been thoroughly examined.Finally,the progress made in cellulose con-version to isosorbide is summarized,current challenges are highlighted,and future development trends are pro-jected in this review.
文摘Advancements in artificial intelligence and big data technologies have led to the gradual emergence of intelligent ships,which are expected to dominate the future of maritime transportation.Supporting the navigation of intelligent ships,route planning technologies have developed many route planning algorithms that prioritize economy and safety.This paper conducts an in-depth study of algorithm efficiency for a route planning problem,proposing an intelligent ship route planning algorithm based on the adaptive step size Informed-RRT^(*).This algorithm can quickly plan a short route according to automatic obstacle avoidance and is suitable for planning the routes of intelligent ships.Results show that the adaptive step size Informed-RRT^(*) algorithm can shorten the optimal route length by approximately 13.05%while ensuring the running time of the planning algorithm and avoiding approximately 23.64%of redundant sampling nodes.The improved algorithm effectively circumvents unnecessary calculations and reduces a large amount of redundant sampling data,thus improving the efficiency of route planning.In a complex water environment,the unique adaptive step size mechanism enables this algorithm to prevent restricted search tree expansion,showing strong search ability and robustness,which is of practical significance for the development of intelligent ships.
文摘demand for faster vessels continues to grow,various high speed vessels have been designed and constructed for military,recreational,and passenger use.Planing vessels,specifically engineered for high-speed travel,require optimization to improve their hydrodynamic performance and stability during design.Reducing resistance and improving longitudinal stability are key challenges in the design of high-speed vessels.Various methods are employed to overcome these challenges,with the use of a transverse step being one of the most common approaches.This study explores the effect of changing the angle of the aft-wise step and incorporates these changes into existing analytical formulas,resulting in new formulas specifically for high-speed vessels equipped with aft-wise steps.This research investigates how the angle of the transverse step affects the hydrodynamic performance and longitudinal stability of high-speed vessels.Based on the results,analytical formulas have been developed to calculate the wetted surface parameters of vessels equipped with an aft-wise transverse step.The study used experimental methods to analyze the vessel's behavior with six different aft-wise transverse step angles of 0°,9°,11°,13°,15°,and 17°at three speeds of 8,10,and 12 m/s.In the experimental tests,the hydrodynamic components of resistance,trim angle,and wetted surface of the vessel were measured.Results indicate that creating an angle in the transverse step substantially improves the hydrodynamic components and longitudinal stability of the vessel.At the optimal angle,the resistance and trim angle of the vessel were reduced by 7.8%and 12.8%,respectively,compared to the base vessel.Additionally,the existing analytical methods for calculating the wetted surface area are more accurate than similar methods.
基金Supported by the Optimization Theory and Algorithm Research Team(23kytdzd004)the General Programs for Young Teacher Cultivation of Educational Commission of Anhui Province of China(YQYB2023090)the University Science Research Project of Anhui Province(2024AH050631)。
文摘In this paper,a fu-Newton step interior-point algorithm is proposed for solving P_(*)(k)-linear complementarity problem based on a new search direction,which is an extension of Grimes'algorithm.It is proved that the number of iterations of the algorithm is O(n^(1/2)(1+4κ)logn/ε),which matches the best known iteration bound of the interior-point method for P_(*)(k)-linear complementarity problem.Some numerical results have proved the feasibility and efficiency of the proposed algorithm.
基金Sponsored by the Natural Science Foundation of Shaanxi Province (Grant No. S2025-JC-YB-0532)the Practice and Innovation Funds for Graduate Students of Northwestern Polytechnical University (PF2024044)
文摘Taking a C1x motor with a backward-facing step which can generate a typical corner vortex as a reference,a numerical methodology using large eddy simulation was established in this study.Based on this methodology,the position of the backward-facing step of the motor was computed and analyzed to determine a basic configuration.Two key geometrical parameters,the head cavity angle and submerged nozzle cavity height,were subsequently introduced.Their effects on the corner vortex motion and their interactions with the acoustic pressure downstream of the backward-facing step were analyzed.The phenomena of vortex acoustic coupling and characteristics of pressure oscillations were further explored.The results show that the maximum error between the simulations and experimental data on the dominant frequency of pressure oscillations is 5.23%,which indicates that the numerical methodology built in this study is highly accurate.When the step is located at less than 5/8 of the total length of the combustion chamber,vortex acoustic coupling occurs,which can increase the pressure oscillations in the motor.Both the vorticity and the scale of vortices in the downstream step increase when the head cavity angle is greater than 24°,which increases the amplitude of the pressure oscillation by maximum 63.0%.The submerged nozzle cavity mainly affects the vortices in the cavity itself rather than those in the downstream step.When the height of the cavity increases from 10 to 20 mm,the pressure oscillation amplitude under the main frequency increases by 39.1%.As this height continues to increase,the amplitude of pressure oscillations increases but the primary frequency decreases.
基金Supported by Opening Program of Physiologial Key Laboratory for Cultivation of Tropical Crops in Hainan Province(Key Opening Bio-logial Laboratory of Rubber of Ministry of Agriculture/Breeding Basein State and Provincial Key Laboratory)(KLOF0907)Major and Special Program for Cultivation of Genetically Modified New Varieties(No.2009ZX08012-014B)+1 种基金National Natural Science Foundation of China(No.30971711)Natural Science Foundation in Jiangsu Province(No.BK2009309)~~
文摘[Objective] The aim of this study was to extract RNA,DNA and protein from plants by using modified one step method.[Method]CTAB was used for the modifying of Biozol-based one step extraction method,which was then used for the isolation of RNA,DNA and protein from the roots of maize（Zea mays L.）,soybean（Glycine max L.）,alfalfa（Medicago sativa L.）and cucumber（Cucumis sativus L.）.And the heme oxygenase-1 gene（HO-1）and calcium-dependent protein kinase-1 gene（CDPK1）,as well as HO-1 protein were identified.[Result]The result of UV spectrophotometer determination and agarose gel electrophoresis analysis showed that the purity of obtained RNA and DNA sample was relatively high;HO-1 and CDPK1 gene exhibited the positive signals checked by RT-PCR;the extracted protein could be used for western blotting analysis;the whole isolation procedure cost 3 h.[Conclusion]This method can be used as a good reference for researcher and will offer a better value with a wide range of applications.
基金supported by National Natural Science Foundation of China through Grant Nos.52495000,52332012 and 52176093partially supported by Beijing Huiyangdao Health Technology Co.,Ltd。
文摘Bionic microfluidics is garnering increasing attention due to the superior fluidic performance enabled by biomimetic microstructures.Inspired by the unique structures of young pumpkin stems,we fabricate helicoidally patterned microchannels with precisely controlled morphologies using the projection micro-stereolithography(PμSL)-based 3D printing technique.Our helicoidally patterned microchannels achieve approximately twice the liquid lifting height compared to similarly sized smooth microchannels.This improvement is attributed to the enhanced capillary force.The additional meniscus formed between the helicoidally patterned microstructures significantly contributes to the increased capillary effects.Furthermore,the underlying mechanisms of fluidic performance in helicoidally patterned microchannels are theorized using a newly developed equation,which is also employed to optimize the geometric parameters and fluidic performance of the biomimetic helicoidal microchannels.Additionally,our biomimetic helicoidally patterned microchannels facilitate a significant step-lifting phenomenon,mimicking tall trees'transpiration.The fluidic performance of our biomimetic helicoidally patterned microchannels show promise for applications in enhanced liquid lifting,step-lifting,clean-water production,and others.
文摘Dear Editor,Sleep plays a vital role in physical health,influencing chronic diseases,memory,and overall quality of life[1,2].In recent years,the relationship between sleep health and physical activity has gained attention,with a particular focus on how daily step count affects various sleep metrics.
基金Projects(52208369,52309138,52108320)supported by the National Natural Science Foundation of ChinaProjects(2023NSFSC0284,2025ZNSFSC0409)supported by the Sichuan Science and Technology Program,ChinaProject(U22468214)supported by the Joint Fund Project for Railway Basic Research by the National Natural Science Foundation of China and China State Railway Group Co.,Ltd.
文摘In the practical slope engineering,the stability of lower sliding mass(region A)with back tensile cracks of the jointed rock slope attracts more attentions,but the upper rock mass(region B)may also be unstable.Therefore,in this study,based on the stepped failure mode of bedding jointed rock slopes,considering the influence of the upper rock mass on the lower stepped sliding mass,the improved failure model for analyzing the interaction force(F_(AB))between two regions is constructed,and the safety factors(F_(S))of two regions and whole region are derived.In addition,this paper proposes a method to determine the existence of F_(AB) using their respective acceleration values(a_(A) and a_(B))when regions A and B are unstable.The influences of key parameters on two regions and the whole region are analyzed.The results show that the variation of the F_(AB) and F_(S) of two regions can be obtained accurately based on the improved failure model.The accuracy of the improved failure model is verified by comparative analysis.The research results can explain the interaction mechanism of two regions and the natural phenomenon of slope failure caused by the development of cracks.
文摘BACKGROUND Owing to age-related physiological declines,elderly patients undergoing radical gastrectomy(RG)often experience physical and psychological challenges.Hence,appropriate nursing strategies need to be identified for optimizing patient outcomes.AIM To evaluate the effects of the Neuman Systems Model-guided stepped care intervention(NGSC)model on postoperative physical and psychological recovery in elderly patients with gastric cancer who underwent RG.METHODS In total,80 elderly patients(≥65 years old)who underwent RG at the Shanxi Fenyang Hospital between January 2023 and June 2024 were included and randomly divided as follows:Control group(n=40,those receiving conventional stepped care intervention);observation group(n=40,those receiving NGSC).Postoperative recovery indices,anxiety/depression scores(Self-Rating Anxiety Scale/Self-Rating Depression Scale),quality of life(36-item short form health survey),and adverse event rates were compared between the groups.RESULTS Compared with the control group,the observation group presented significantly shorter recovery times for first bowel sounds,ambulation,flatus,oral intake,catheter removal,and hospitalization(all P<0.05).Notably,in the observation group,Self-Rating Anxiety Scale/Self-Rating Depression Scale scores and the adverse event rate were significantly lower(all P<0.05),whereas 36-item short form health survey scores were higher(P<0.05),compared with those in the control group.CONCLUSION Overall,the findings of this study show that the proposed NGSC model accelerates postoperative recovery,alleviates psychological distress,improves quality of life,and reduces complications in elderly patients with gastric cancer who underwent RG,presenting potential for clinical application.
文摘Aim To analyze dynamic failure of aerospace strutures subjected lateral impulsive loading. Methods Structures were modeled as rigid-perfectly plastic free-free stepped beams. Basic equations of motion un set up for analysis. Results Final pat deformation and rigid motion solutions were determined for a uniform impulsive loading. The critical rupture conditions for a space shuttle and a missile were obtained. Conclusion Failure is possible for aerospace structures under a uniform impulsive loading, but it is mere difficult in space.
文摘An idealized numerical wave flume has been established by finite element method on the bases of Navier Stokes equations through prescribing the appropriate boundary conditions for the open boundary,incident boundary,free surface and solid boundary in this paper.The characteristics of waves propagating over a step have been investigated by this numerical model.The breaker wave height is determined depending on the kinetic criterion.The numerical model is verified by laboratory experiments,and the empirical formula for the damping of wave height due to breaking is also given by experiments.
基金supported by the National Natural Science Foundation of China(Grant No.51079157)
文摘A growing interest has been devoted to the contra-rotating propellers （CRPs） due to their high propulsive efficiency, torque balance, low fuel consumption, low cavitations, low noise performance and low hull vibration. Compared with the single-screw system, it is more difficult for the open water performance prediction because forward and aft propellers interact with each other and generate a more complicated flow field around the CRPs system. The current work focuses on the open water performance prediction of contra-rotating propellers by RANS and sliding mesh method considering the effect of computational time step size and turbulence model. The validation study has been performed on two sets of contra-rotating propellers developed by David W Taylor Naval Ship R ＆ D center. Compared with the experimental data, it shows that RANS with sliding mesh method and SST k-ω turbulence model has a good precision in the open water performance prediction of contra-rotating propellers, and small time step size can improve the level of accuracy for CRPs with the same blade number of forward and aft propellers, while a relatively large time step size is a better choice for CRPs with different blade numbers.
