Debris flow drainage canal is one of the most widely used engineering measures to prevent and manage debris flow hazards.The shape and the sizes of the cross-section are important parameters when design debris flow dr...Debris flow drainage canal is one of the most widely used engineering measures to prevent and manage debris flow hazards.The shape and the sizes of the cross-section are important parameters when design debris flow drainage canal.Therefore,how to design the appropriate shape and sizes of the cross-section so that the drainage canal can have the optimal drainage capacity is very important and few researched at home and abroad.This study was conducted to analyze the hydraulic condition of a Trapezoid-V shaped drainage canal and optimize its cross-section.By assuming characteristic sizes of the cross-section,the paper deduced the configuration parameter of the cross-section of a Trapezoid-V shaped debris flow drainage canal.By theory analysis,it indicates that the optimal configuration parameter is only related to the side slope coefficient and the bottom transverse slope coefficient.For this study,the Heishui Gully,a first-order tributary of the lower Jinsha River,was used as an example to design the optimal cross-section of the drainage canal of debris flow.展开更多
Based on the traditional Smoothed Particle Hydrodynamics (SPH) algorithm, the linked-list search algorithm combined with the variable smoothing length and square support domain was put forward to improve the calculati...Based on the traditional Smoothed Particle Hydrodynamics (SPH) algorithm, the linked-list search algorithm combined with the variable smoothing length and square support domain was put forward to improve the calculation efficiency and guarantee the calculation accuracy. The physical process of high velocity fragment impact on a broadside liquid cabin was programmed for simulation. The numerical results agreed well with those of the general software ANSYS AUTODYN, which verifies the effectiveness and feasibility of the numerical method. From the perspective of the outer plate thickness of the liquid cabin, the width of the liquid cabin, and incident angle of the fragment, the influence of these parameters on protective mechanisms was analyzed to provide a basis for protective design of a broadside liquid cabin. Results show that the influence of outer plate thickness is not obvious; therefore, the conventional design can be adopted in the design of the outer plate. The width of the liquid cabin has a great influence on the residual velocity of the fragment and the width of the liquid cabin should be designed to be as wide as possible under the premise of meeting other requirements. There is a certain incident angle in which the velocity attenuation of the fragment is most obvious, and the high-pressure zone near the inner plate is asymmetric. The inner plate of liquid cabin should be strengthened according to the hull form, principal dimensions, and vulnerable points.展开更多
Due to the unique deformation characteristics of auxetic materials(Poisson’s ratioμ<0),they have better shock resistance and energy absorption properties than traditional materials.Inspired by the concept of vari...Due to the unique deformation characteristics of auxetic materials(Poisson’s ratioμ<0),they have better shock resistance and energy absorption properties than traditional materials.Inspired by the concept of variable crosssection design,a new auxetic re-entrant honeycomb structure is designed in this study.The detailed design method of re-entrant honeycomb with variable cross-section(VCRH)is provided,and five VCRH structures with the same relative density and different cross-section change rates are proposed.The in-plane impact resistance and energy absorption abilities of VCRH under constant velocity are investigated by ABAQUS/EXPLICIT.The results show that the introduction of variable cross-section design can effectively improve the impact resistance and energy absorption abilities of auxetic re-entrant honeycombs.The VCRH structure has better Young’s modulus,plateau stress,and specific energy absorption(SEA)than traditional re-entrant honeycomb(RH).The influence of microstructure parameters(such as cross-section change rateα)on the dynamic impact performance of VCRH is also studied.Results show that,with the increase in impact velocity andα,the plateau stress and SEA of VCRH increase.A positive correlation is also found between the energy absorption efficiency,impact load uniformity andαunder both medium and high impact speeds.These results can provide a reference for designing improved auxetic re-entrant honeycomb structures.展开更多
This article proposes use of extruded compound materials with optimized resistant cross-sections as an alternative, in this case, seeking the maximum energy density as a design criterion. The advantage of this proposa...This article proposes use of extruded compound materials with optimized resistant cross-sections as an alternative, in this case, seeking the maximum energy density as a design criterion. The advantage of this proposal is that it extends the life cycle and decreases fatigue issues.展开更多
Background: Orthodontic treatment poses challenges such as discomfort, aesthetic concerns, dietary restrictions, time commitment, and financial considerations for patients. These challenges can deter individuals from ...Background: Orthodontic treatment poses challenges such as discomfort, aesthetic concerns, dietary restrictions, time commitment, and financial considerations for patients. These challenges can deter individuals from pursuing treatment or cause anxiety during the process. However, patients are motivated by the desire to improve their appearance, boost self-confidence, and enhance oral health. They also value the long-term benefits of treatment, including improved dental function and overall well-being. Professional recommendations from dentists and orthodontists, along with social support from family and friends, further encourage patients to undergo treatment. Understanding these challenges and motivating factors is crucial for orthodontic professionals to tailor treatment plans and ensure positive experiences and successful outcomes for their patients. Objective: To determine the challenges and motivating factors of orthodontic treatment among patients attending Komfo Anokye Teaching Hospital. Method: The study was conducted at Komfo Anokye Teaching Hospital in Kumasi, Ghana, with a sample size of 60 orthodontic patients. Data was collected using self-administered questionnaires and analyzed using SPSS software. Ethical approval was obtained, and the findings were shared with stakeholders. Results: Findings showed a higher representation of females (63.3%) seeking orthodontic treatment. Common motivations for seeking orthodontic treatment included aesthetic Concerns (38.2%), misaligned teeth (28.1%) and recommendation from dentist (19.2%). Challenges reported included pain and discomfort (36.7%), difficulty chewing (15%), expensive treatment (14.4%) and missed appointments (11.7%). Factors motivating treatment continuation were visible improvements (30%), achieving optimal results (23%), reducing pain and discomfort (17%). External influences, such as family pressure, also played a role. Patients appreciated the support of healthcare providers during treatment but suggested better pain management and education. Conclusion: The study provided valuable insights into patient motivations, challenges and factors influencing satisfaction and adherence to orthodontic treatment at KATH.展开更多
基金supported by the National Science and Technology Supporting Plan (Grant No. 2009BAK56B05)Key Project of Chinese National Programs for Fundamental Research and Development (973 Program) (Grant No. 2008CB425803)
文摘Debris flow drainage canal is one of the most widely used engineering measures to prevent and manage debris flow hazards.The shape and the sizes of the cross-section are important parameters when design debris flow drainage canal.Therefore,how to design the appropriate shape and sizes of the cross-section so that the drainage canal can have the optimal drainage capacity is very important and few researched at home and abroad.This study was conducted to analyze the hydraulic condition of a Trapezoid-V shaped drainage canal and optimize its cross-section.By assuming characteristic sizes of the cross-section,the paper deduced the configuration parameter of the cross-section of a Trapezoid-V shaped debris flow drainage canal.By theory analysis,it indicates that the optimal configuration parameter is only related to the side slope coefficient and the bottom transverse slope coefficient.For this study,the Heishui Gully,a first-order tributary of the lower Jinsha River,was used as an example to design the optimal cross-section of the drainage canal of debris flow.
基金Supported by the Lloyds Register Educational Trust (the LRET)Key Project of National Natural Science Funds(50939002)the National Natural Science Fundation of China (50809018)
文摘Based on the traditional Smoothed Particle Hydrodynamics (SPH) algorithm, the linked-list search algorithm combined with the variable smoothing length and square support domain was put forward to improve the calculation efficiency and guarantee the calculation accuracy. The physical process of high velocity fragment impact on a broadside liquid cabin was programmed for simulation. The numerical results agreed well with those of the general software ANSYS AUTODYN, which verifies the effectiveness and feasibility of the numerical method. From the perspective of the outer plate thickness of the liquid cabin, the width of the liquid cabin, and incident angle of the fragment, the influence of these parameters on protective mechanisms was analyzed to provide a basis for protective design of a broadside liquid cabin. Results show that the influence of outer plate thickness is not obvious; therefore, the conventional design can be adopted in the design of the outer plate. The width of the liquid cabin has a great influence on the residual velocity of the fragment and the width of the liquid cabin should be designed to be as wide as possible under the premise of meeting other requirements. There is a certain incident angle in which the velocity attenuation of the fragment is most obvious, and the high-pressure zone near the inner plate is asymmetric. The inner plate of liquid cabin should be strengthened according to the hull form, principal dimensions, and vulnerable points.
基金This research is supported by the National Natural Science Foundation of China(No.11902232).
文摘Due to the unique deformation characteristics of auxetic materials(Poisson’s ratioμ<0),they have better shock resistance and energy absorption properties than traditional materials.Inspired by the concept of variable crosssection design,a new auxetic re-entrant honeycomb structure is designed in this study.The detailed design method of re-entrant honeycomb with variable cross-section(VCRH)is provided,and five VCRH structures with the same relative density and different cross-section change rates are proposed.The in-plane impact resistance and energy absorption abilities of VCRH under constant velocity are investigated by ABAQUS/EXPLICIT.The results show that the introduction of variable cross-section design can effectively improve the impact resistance and energy absorption abilities of auxetic re-entrant honeycombs.The VCRH structure has better Young’s modulus,plateau stress,and specific energy absorption(SEA)than traditional re-entrant honeycomb(RH).The influence of microstructure parameters(such as cross-section change rateα)on the dynamic impact performance of VCRH is also studied.Results show that,with the increase in impact velocity andα,the plateau stress and SEA of VCRH increase.A positive correlation is also found between the energy absorption efficiency,impact load uniformity andαunder both medium and high impact speeds.These results can provide a reference for designing improved auxetic re-entrant honeycomb structures.
文摘This article proposes use of extruded compound materials with optimized resistant cross-sections as an alternative, in this case, seeking the maximum energy density as a design criterion. The advantage of this proposal is that it extends the life cycle and decreases fatigue issues.
文摘Background: Orthodontic treatment poses challenges such as discomfort, aesthetic concerns, dietary restrictions, time commitment, and financial considerations for patients. These challenges can deter individuals from pursuing treatment or cause anxiety during the process. However, patients are motivated by the desire to improve their appearance, boost self-confidence, and enhance oral health. They also value the long-term benefits of treatment, including improved dental function and overall well-being. Professional recommendations from dentists and orthodontists, along with social support from family and friends, further encourage patients to undergo treatment. Understanding these challenges and motivating factors is crucial for orthodontic professionals to tailor treatment plans and ensure positive experiences and successful outcomes for their patients. Objective: To determine the challenges and motivating factors of orthodontic treatment among patients attending Komfo Anokye Teaching Hospital. Method: The study was conducted at Komfo Anokye Teaching Hospital in Kumasi, Ghana, with a sample size of 60 orthodontic patients. Data was collected using self-administered questionnaires and analyzed using SPSS software. Ethical approval was obtained, and the findings were shared with stakeholders. Results: Findings showed a higher representation of females (63.3%) seeking orthodontic treatment. Common motivations for seeking orthodontic treatment included aesthetic Concerns (38.2%), misaligned teeth (28.1%) and recommendation from dentist (19.2%). Challenges reported included pain and discomfort (36.7%), difficulty chewing (15%), expensive treatment (14.4%) and missed appointments (11.7%). Factors motivating treatment continuation were visible improvements (30%), achieving optimal results (23%), reducing pain and discomfort (17%). External influences, such as family pressure, also played a role. Patients appreciated the support of healthcare providers during treatment but suggested better pain management and education. Conclusion: The study provided valuable insights into patient motivations, challenges and factors influencing satisfaction and adherence to orthodontic treatment at KATH.
