Ultrasonic scalpel design for minimally invasive surgical procedures is mainly focused on optimizing cutting performance.However,an important issue is the low fatigue life of traditional ultrasonic scalpels,which affe...Ultrasonic scalpel design for minimally invasive surgical procedures is mainly focused on optimizing cutting performance.However,an important issue is the low fatigue life of traditional ultrasonic scalpels,which affects their long-term reliability and effectiveness and creates hidden dangers for surgery.In this study,a multi-objective optimal design for the cutting performance and fatigue life of ultrasonic scalpels was proposed using finite element analysis and fatigue simulation.The optimal design parameters of resonance frequency and amplitude were determined.By setting the transition fillet and keeping the gain structure away from the node position to enable the scalpel to have a high service life with excellent cutting performance.The frequency modulation method of setting the vibration node bosses at the node position and setting the vibration antinode grooves at the antinode position was compared.Then,the mechanism of the influence of various design elements,such as tip,shank,node position,and antinode position,on the resonance frequency,amplitude,and fatigue life of the ultrasonic scalpel was analyzed,and the optimal design principles of the ultrasonic scalpel were obtained.The proposed ultrasonic scalpel design was confirmed by simulations,impedance measurements,and liver tissue cutting experiments,demonstrating its feasibility and enhanced performance.This research introduces innovative design strategies to improve the fatigue life and performance of ultrasonic scalpels to address an important issue in minimally invasive surgery.展开更多
In this paper the use of lime stabilized subgrade for low volume roads in two regions with high mountains and different frost penetration conditions in Türkiye was investigated in terms of design,performance,and ...In this paper the use of lime stabilized subgrade for low volume roads in two regions with high mountains and different frost penetration conditions in Türkiye was investigated in terms of design,performance,and cost.Pavements on unstabilized and stabilized subgrade were designed for two regions(Izmir and Van),covering all climate variations.The resilient modulus of the lime stabilized subgrade with different soil pulverization levels for non-freezing and freezing conditions were taken from a previous laboratory study.Frost effects were considered in pavement design using two different approaches,including limited subgrade frost penetration method and reduced subgrade strength method.Detailed application and evaluation were performed for all steps.Lime stabilized subgrades significantly reduced the thickness of base courses,and the benefit of lime stabilization was highly dependent on soil pulverization level.A detailed cost analysis on the unstabilized and stabilized cases found that the use of lime stabilization in the subgrade provided significant initial cost savings.Comparative analysis by using the AASHTO(1993)method and KENPAVE software,and quantity effect of soil pulverization level on the performance of low volume roads from a service life perspective,show that subgrade resilient modulus can be estimated.It is also possible to make correct performance estimation in the field.The results of the study show that lime stabilization is a good solution for low volume roads in the mountainous regions of Türkiye.展开更多
The basic element in any sustainable dam project is safety, which includes the following safety elements： O structural safety, dam safety monitoring, operational safety and maintenance, and emergency planning. Lon...The basic element in any sustainable dam project is safety, which includes the following safety elements： O structural safety, dam safety monitoring, operational safety and maintenance, and emergency planning. Long-term safety primarily includes the analysis of all hazards affecting the project; that is, hazards from the natural environment, hazards from the man-made environment, and project-specific and site-specific hazards. The special features of the seismic safety of dams are discussed. Large dams were the first structures to be systematically designed against earthquakes, starting in the 1930s. How- ever, the seismic safety of older dams is unknown, as most were designed using seismic design criteria and methods of dynamic analysis that are considered obsolete today. Therefore, we need to reevaluate the seismic safety of existing dams based on current state-of-the-art practices and rehabilitate deficient dams. For large dams, a site-specific seismic hazard analysis is usually recommended. Today, large dams and the safety-relevant elements used for controlling the reservoir after a strong earthquake must be able to withstand the ground motions of a safety evaluation earthquake. The ground motion parameters can be determined either by a probabilistic or a deterministic seismic hazard analysis. During strong earthquakes, inelastic deformations may occur in a dam; therefore, the seismic analysis has to be car- ried out in the time domain. Furthermore, earthquakes create multiple seismic hazards for dams such as ground shaking, fault movements, mass movements, and others. The ground motions needed by the dam engineer are not real earthquake ground motions but models of the ground motion, which allow the safe design of dams. It must also be kept in mind that darn safety evaluations must be carried out several times during the long life of large storage dams. These features are discussed in this paper.展开更多
Durability problem of reinforced concrete for underground structures is a hot issue in the field of structural engineering. For underground structures, the prediction of structural service life and methodology for dur...Durability problem of reinforced concrete for underground structures is a hot issue in the field of structural engineering. For underground structures, the prediction of structural service life and methodology for durability design are needed to estimate structural durability. Taking the case of Xiamen Xiang＇an subsea tunnel as background, which is designed to meet the requirement of lO0-year service life, the influential factors on tunnel lining durability are analyzed. Under the criteria of crack controlling and bearing capacity of linin~ structures, the theoretical service life of Xiamen Xiang＇an subsea tunnel lining is studied. The regulations, which are needed for the diffusion capability of chloride ions in concrete by the relevant diffusion tests, are proposed. After a quick corrosion test, the bearing capacity test on eccentric short columns is implemented to investigate the variation rules in the bearing capacity of models with time. Influence of the corrosion degree of steel bars on the bearing capacity of models is also investigated. Based on the results of model tests, the acceleration ratio between the quick corrosion in laboratory test and the natural corrosion environments is established. Thus, the natural service life of subsea tunnel lining structures can be obtained by means of laboratory tests. Then, the proposed method using this modified model is employed to predict the service life of tunnel lining structures. Finally, the design and construction measures for improving the durability of lining structures of subsea tunnel are introduced. The proposed method in the present study based on a real engineering project is superior to those with only theoretical assumptions, and would be more suitable for similar projects.展开更多
This review paper discusses the polymeric materials most commonly used in construction industry,where the main considerations and design recommendations for durability are reviewed.Besides,it aims to provide useful in...This review paper discusses the polymeric materials most commonly used in construction industry,where the main considerations and design recommendations for durability are reviewed.Besides,it aims to provide useful insights and information to professionals and researchers in areas related to construction and architectural materials to help them to make decisions when selecting materials from sustainable and durable design.The methodology was based on a review of scientific literature,where the main properties of polymeric materials were identified in the main considerations for the durable design of each polymeric material.We conclude that these materials consume large amounts of resources and energy in their process of manufacture,so,their use should be restricted.However,at the same time,they are durable and recyclable building materials with good operation and service life,especially serve as sealants,insulation,paints,pipes,window frames and exterior finishes.展开更多
基金Supported by National Natural Science Foundation of China (Grant Nos.52005199,42241149)Shenzhen Fundamental Research Program of China (Grant Nos.JCYJ20200109150425085,JCYJ20220818102601004)+1 种基金Knowledge Innovation Program of Wuhan-Basic Research of China (Grant No.2022010801010203)Shenzhen Science and Technology Program of China (Grant Nos.JSGG20201103100001004,JSGG20220831105800001)。
文摘Ultrasonic scalpel design for minimally invasive surgical procedures is mainly focused on optimizing cutting performance.However,an important issue is the low fatigue life of traditional ultrasonic scalpels,which affects their long-term reliability and effectiveness and creates hidden dangers for surgery.In this study,a multi-objective optimal design for the cutting performance and fatigue life of ultrasonic scalpels was proposed using finite element analysis and fatigue simulation.The optimal design parameters of resonance frequency and amplitude were determined.By setting the transition fillet and keeping the gain structure away from the node position to enable the scalpel to have a high service life with excellent cutting performance.The frequency modulation method of setting the vibration node bosses at the node position and setting the vibration antinode grooves at the antinode position was compared.Then,the mechanism of the influence of various design elements,such as tip,shank,node position,and antinode position,on the resonance frequency,amplitude,and fatigue life of the ultrasonic scalpel was analyzed,and the optimal design principles of the ultrasonic scalpel were obtained.The proposed ultrasonic scalpel design was confirmed by simulations,impedance measurements,and liver tissue cutting experiments,demonstrating its feasibility and enhanced performance.This research introduces innovative design strategies to improve the fatigue life and performance of ultrasonic scalpels to address an important issue in minimally invasive surgery.
基金a joint venture project between Istanbul University and the Turkish General Directorate of Highways by project number KGM-ARGE/2012-25funded by Istanbul University-Cerrahpasa Scientific Research Projects under Project No:ACIP 54739。
文摘In this paper the use of lime stabilized subgrade for low volume roads in two regions with high mountains and different frost penetration conditions in Türkiye was investigated in terms of design,performance,and cost.Pavements on unstabilized and stabilized subgrade were designed for two regions(Izmir and Van),covering all climate variations.The resilient modulus of the lime stabilized subgrade with different soil pulverization levels for non-freezing and freezing conditions were taken from a previous laboratory study.Frost effects were considered in pavement design using two different approaches,including limited subgrade frost penetration method and reduced subgrade strength method.Detailed application and evaluation were performed for all steps.Lime stabilized subgrades significantly reduced the thickness of base courses,and the benefit of lime stabilization was highly dependent on soil pulverization level.A detailed cost analysis on the unstabilized and stabilized cases found that the use of lime stabilization in the subgrade provided significant initial cost savings.Comparative analysis by using the AASHTO(1993)method and KENPAVE software,and quantity effect of soil pulverization level on the performance of low volume roads from a service life perspective,show that subgrade resilient modulus can be estimated.It is also possible to make correct performance estimation in the field.The results of the study show that lime stabilization is a good solution for low volume roads in the mountainous regions of Türkiye.
文摘The basic element in any sustainable dam project is safety, which includes the following safety elements： O structural safety, dam safety monitoring, operational safety and maintenance, and emergency planning. Long-term safety primarily includes the analysis of all hazards affecting the project; that is, hazards from the natural environment, hazards from the man-made environment, and project-specific and site-specific hazards. The special features of the seismic safety of dams are discussed. Large dams were the first structures to be systematically designed against earthquakes, starting in the 1930s. How- ever, the seismic safety of older dams is unknown, as most were designed using seismic design criteria and methods of dynamic analysis that are considered obsolete today. Therefore, we need to reevaluate the seismic safety of existing dams based on current state-of-the-art practices and rehabilitate deficient dams. For large dams, a site-specific seismic hazard analysis is usually recommended. Today, large dams and the safety-relevant elements used for controlling the reservoir after a strong earthquake must be able to withstand the ground motions of a safety evaluation earthquake. The ground motion parameters can be determined either by a probabilistic or a deterministic seismic hazard analysis. During strong earthquakes, inelastic deformations may occur in a dam; therefore, the seismic analysis has to be car- ried out in the time domain. Furthermore, earthquakes create multiple seismic hazards for dams such as ground shaking, fault movements, mass movements, and others. The ground motions needed by the dam engineer are not real earthquake ground motions but models of the ground motion, which allow the safe design of dams. It must also be kept in mind that darn safety evaluations must be carried out several times during the long life of large storage dams. These features are discussed in this paper.
文摘Durability problem of reinforced concrete for underground structures is a hot issue in the field of structural engineering. For underground structures, the prediction of structural service life and methodology for durability design are needed to estimate structural durability. Taking the case of Xiamen Xiang＇an subsea tunnel as background, which is designed to meet the requirement of lO0-year service life, the influential factors on tunnel lining durability are analyzed. Under the criteria of crack controlling and bearing capacity of linin~ structures, the theoretical service life of Xiamen Xiang＇an subsea tunnel lining is studied. The regulations, which are needed for the diffusion capability of chloride ions in concrete by the relevant diffusion tests, are proposed. After a quick corrosion test, the bearing capacity test on eccentric short columns is implemented to investigate the variation rules in the bearing capacity of models with time. Influence of the corrosion degree of steel bars on the bearing capacity of models is also investigated. Based on the results of model tests, the acceleration ratio between the quick corrosion in laboratory test and the natural corrosion environments is established. Thus, the natural service life of subsea tunnel lining structures can be obtained by means of laboratory tests. Then, the proposed method using this modified model is employed to predict the service life of tunnel lining structures. Finally, the design and construction measures for improving the durability of lining structures of subsea tunnel are introduced. The proposed method in the present study based on a real engineering project is superior to those with only theoretical assumptions, and would be more suitable for similar projects.
文摘This review paper discusses the polymeric materials most commonly used in construction industry,where the main considerations and design recommendations for durability are reviewed.Besides,it aims to provide useful insights and information to professionals and researchers in areas related to construction and architectural materials to help them to make decisions when selecting materials from sustainable and durable design.The methodology was based on a review of scientific literature,where the main properties of polymeric materials were identified in the main considerations for the durable design of each polymeric material.We conclude that these materials consume large amounts of resources and energy in their process of manufacture,so,their use should be restricted.However,at the same time,they are durable and recyclable building materials with good operation and service life,especially serve as sealants,insulation,paints,pipes,window frames and exterior finishes.
