近年来全球极端低温天气频发,严重影响了茶树的产量和品质。ICE(Inducer of CBF expression)基因家族主要参与植物的低温胁迫响应,但在茶树领域中的相关研究还不够全面。本研究从茶树基因组中鉴定出51个茶树CsICEs基因,对其理化性质、...近年来全球极端低温天气频发,严重影响了茶树的产量和品质。ICE(Inducer of CBF expression)基因家族主要参与植物的低温胁迫响应,但在茶树领域中的相关研究还不够全面。本研究从茶树基因组中鉴定出51个茶树CsICEs基因,对其理化性质、基因结构和启动子顺式作用元件展开生物信息学分析。茶树CsICEs基因的启动子区域富含光响应、植物激素、生长发育及非生物胁迫相关顺式作用元件,其可能参与多种逆境胁迫响应。转录组分析和RT-qPCR验证结果发现,低温下CsICE43基因的表达量上升了4.24倍,其可能与茶树低温响应相关。以茶树品种‘保靖黄金茶1号’的cDNA为模板,克隆获得了CsICE43基因,其在不同组织中的表达模式存在差异,在顶芽和嫩叶中特异性高表达。蛋白氨基酸序列和系统进化树分析表明,CsICE43基因包含与ICE家族其他成员一致的S-rich、bHLH、ACT等保守结构域,且与毛花猕猴桃(Actinidiaeriantha)的亲缘关系较近。在STRING在线网站中以拟南芥AtICEs为模型,推测茶树CsICE43蛋白与HOS1、MYB15、DREB1/2存在潜在的互作关系。亚细胞定位试验表明CsICE43定位于细胞核,与跨膜结构分析结果一致。综上所述,本研究发现CsICE43基因可能与茶树低温响应关联,为深入挖掘其基因功能与抗寒分子机理提供了一定的理论基础。展开更多
Ice-going ships play a crucial role in polar transportation and resource extraction.Different from the existing modeling approach which assumes that ships remain stationary,dynamic overset grid technology and DFBI(Dyn...Ice-going ships play a crucial role in polar transportation and resource extraction.Different from the existing modeling approach which assumes that ships remain stationary,dynamic overset grid technology and DFBI(Dynamic Fluid-Body Interaction)method are employed in this paper to enable the free-running motion of the ship in modeling.A numerical model capable of simulating a ship navigating through pack ice area is proposed,which uses Computational Fluid Dynamics(CFD)method to solve the flow field and applies the Discrete Element Method(DEM)to simulate ship-ice and ice-ice interactions.Besides,the proposed high-precision method for generating pack ice area can be used in conjunction with the proposed numerical model.By comparing the numerical results with the available model test data and experimental observations,the effectiveness of the numerical model is validated,demonstrating its strong capability of predicting resistance and simulating ship navigation in pack ice,as well as its significant potential and applicability for further studies.展开更多
Ice load on underwater vehicles breaking through ice covers from underneath is a significant concern for researchers in polar exploration,and the research on this problem is still in its early stages.Both mechanical e...Ice load on underwater vehicles breaking through ice covers from underneath is a significant concern for researchers in polar exploration,and the research on this problem is still in its early stages.Both mechanical experimental measurement and numerical simulation pose research challenges.This study focuses on the ice load of a cylinder structure breaking upward through the ice sheet form underneath in the Small Ice Model Basin of China Ship Scientific Research Center(CSSRC SIMB).A high-speed camera system was employed to observe the ice sheet failure during the tests,in which,with the loading position as center,local radial cracks and circumferential cracks were generated.A load sensor was used to measure the overall ice load during this process.Meanwhile,a numerical model was developed using LS-DYNA for validation and comparison.With this model,numerical simulation was conducted under various ice thicknesses and upgoing speeds to analyze the instantaneous curves of ice load.The calculation results were statistically analyzed under different working conditions to determine the influence of the factors on the ice load of the cylinder.The study explores the measurement method about ice load of objects vertically breaking through model ice sheet and is expected to provide some fundamental insights into the safety design of underwater structures operating in ice waters.展开更多
In the past few decades,the navigation performance of ships and structures in ice-covered waters has not been fully studied,especially the influence of ice mechanical properties on icebreaking ability.Ice bending stre...In the past few decades,the navigation performance of ships and structures in ice-covered waters has not been fully studied,especially the influence of ice mechanical properties on icebreaking ability.Ice bending strength is a key ice parameter for predicting ship ice loads,and accurate ice bending strength is also the key to scaling model tests results to real ship.However,numerical simulation studies on model ice bending strength of ice tanks are often neglected.In this paper,an explicit finite element method model is used to simulate the ice cantilever beam test,and the failure load and bending strength of the ice are obtained.In this model,the Tsai-Wu failure criterion is used as the material constitutive model,and the required simulation parameters are obtained from the model ice test in ice tank.Parameter sensitivity analysis shows that the cantilever beam size of the model ice has a significant effect on the flexural strength.The results show that proper rounding at the root of the cantilever beam is beneficial to reduce stress concentration and obtain more accurate bending strength;the thickness,width and length of the cantilever beam should conform to a certain ratio,and consistent with the ITTC recommended reference.Therefore,the results of this study can promote model ice experiments and numerical studies and provide ice strength data support for ship design and polar ship maneuvering.展开更多
In order to understand the influence of bow shape on ice resistance and provide guidelines for hull line design in the early design stage,an investigation of the impact of bow shape on ice resistance for the Arctic LN...In order to understand the influence of bow shape on ice resistance and provide guidelines for hull line design in the early design stage,an investigation of the impact of bow shape on ice resistance for the Arctic LNG carriers is carried out based on semi-empirical methods.Firstly,some typical semi-empirical formulas developed for ice resistance estimation of cargo carriers in different ice conditions are summarized.Then,formulas appropriate for ice resistance estimation of Arctic LNG carriers under different ice conditions are verified according to the result comparison between semi-empirical formulas and experimental tests.The comparison result indicates that the Lindqvist formula is appropriate for ice resistance estimation in level ice conditions,Zuev and Dobrodeev formula for ice resistance estimation in broken ice conditions,and Dobrodeev formula for ice resistance estimation in brash ice conditions.After that,the parameters considered in the selected formulas are summarized,and the influence of critical parameters on ice resistance is analyzed.Some parameters describing the ship's bow shape characteristic like ship breadth,waterline angle and stem angle greatly influence the ice resistance.Ice resistance increases with both the growth of ship breadth under all ice conditions and the growth of stem angle in level ice and broken ice conditions while ice resistance decreases with the development of waterline angle under all ice conditions.Finally,the optimization of the bow shape is discussed,and an optimized bow shape with both a large waterline angle and low stem angle is proposed.The optimized bow shape can decrease ice resistance by 9.9%in the level ice condition and reduce ice resistance by 11.3%in the brash ice condition.展开更多
Ships navigating in ice-covered regions will inevitably collide with ice ridges.Compared to other ice bodies,ice ridges exhibit more complicated mechanical behaviors due to the scale and structure characteristics.In t...Ships navigating in ice-covered regions will inevitably collide with ice ridges.Compared to other ice bodies,ice ridges exhibit more complicated mechanical behaviors due to the scale and structure characteristics.In this paper,nonlinear finite element method is used to investigate the interaction between a polar ship and an ice ridge.The ice ridge is modelled as elastic-plastic material based on Drucker-Prager yield function,with the consideration of the influence of cohesion,friction angle and material hardening.The material model is developed in LS-DYNA and solved using semi-implicit mapping algorithm.The stress distribution of ice ridge and ship,and the ice load history are evaluated through the simulation of multiple collisions.In addition,parametric analysis is performed to investigate the influence of ridge thickness and impact velocity on the ice load and energy absorption.展开更多
In polar regions, floating ice exhibits distinct characteristics across a range of spatial scales. It is well recognized that the irregular geometry of these ice formations markedly influences their dynamic behavior. ...In polar regions, floating ice exhibits distinct characteristics across a range of spatial scales. It is well recognized that the irregular geometry of these ice formations markedly influences their dynamic behavior. This study introduces a polyhedral Discrete Element Method (DEM) tailored for polar ice, incorporating the Gilbert-Johnson-Keerthi (GJK) and Expanding Polytope Algorithm (EPA) for contact detection. This approach facilitates the simulation of the drift and collision processes of floating ice, effectively capturing its freezing and fragmentation. Subsequently, the stability and reli ability of this model are validated by uniaxial compression on level ice fields, focusing specifically on the influence of compression strength on deformation resistance. Additionally, clusters of ice floes nav igating through narrow channels are simulated. These studies have qualitatively assessed the effects of Floe Size Distribution (FSD), initial concentration, and circularity on their flow dynamics. The higher power-law exponent values in the FSD, increased circularity, and decreased concentration are each as sociated with accelerated flow in ice floe fields. The simulation results distinctly demonstrate the con siderable impact of sea ice geometry on the movement of clusters, offering valuable insights into the complexities of polar ice dynamics.展开更多
文摘近年来全球极端低温天气频发,严重影响了茶树的产量和品质。ICE(Inducer of CBF expression)基因家族主要参与植物的低温胁迫响应,但在茶树领域中的相关研究还不够全面。本研究从茶树基因组中鉴定出51个茶树CsICEs基因,对其理化性质、基因结构和启动子顺式作用元件展开生物信息学分析。茶树CsICEs基因的启动子区域富含光响应、植物激素、生长发育及非生物胁迫相关顺式作用元件,其可能参与多种逆境胁迫响应。转录组分析和RT-qPCR验证结果发现,低温下CsICE43基因的表达量上升了4.24倍,其可能与茶树低温响应相关。以茶树品种‘保靖黄金茶1号’的cDNA为模板,克隆获得了CsICE43基因,其在不同组织中的表达模式存在差异,在顶芽和嫩叶中特异性高表达。蛋白氨基酸序列和系统进化树分析表明,CsICE43基因包含与ICE家族其他成员一致的S-rich、bHLH、ACT等保守结构域,且与毛花猕猴桃(Actinidiaeriantha)的亲缘关系较近。在STRING在线网站中以拟南芥AtICEs为模型,推测茶树CsICE43蛋白与HOS1、MYB15、DREB1/2存在潜在的互作关系。亚细胞定位试验表明CsICE43定位于细胞核,与跨膜结构分析结果一致。综上所述,本研究发现CsICE43基因可能与茶树低温响应关联,为深入挖掘其基因功能与抗寒分子机理提供了一定的理论基础。
文摘Ice-going ships play a crucial role in polar transportation and resource extraction.Different from the existing modeling approach which assumes that ships remain stationary,dynamic overset grid technology and DFBI(Dynamic Fluid-Body Interaction)method are employed in this paper to enable the free-running motion of the ship in modeling.A numerical model capable of simulating a ship navigating through pack ice area is proposed,which uses Computational Fluid Dynamics(CFD)method to solve the flow field and applies the Discrete Element Method(DEM)to simulate ship-ice and ice-ice interactions.Besides,the proposed high-precision method for generating pack ice area can be used in conjunction with the proposed numerical model.By comparing the numerical results with the available model test data and experimental observations,the effectiveness of the numerical model is validated,demonstrating its strong capability of predicting resistance and simulating ship navigation in pack ice,as well as its significant potential and applicability for further studies.
文摘Ice load on underwater vehicles breaking through ice covers from underneath is a significant concern for researchers in polar exploration,and the research on this problem is still in its early stages.Both mechanical experimental measurement and numerical simulation pose research challenges.This study focuses on the ice load of a cylinder structure breaking upward through the ice sheet form underneath in the Small Ice Model Basin of China Ship Scientific Research Center(CSSRC SIMB).A high-speed camera system was employed to observe the ice sheet failure during the tests,in which,with the loading position as center,local radial cracks and circumferential cracks were generated.A load sensor was used to measure the overall ice load during this process.Meanwhile,a numerical model was developed using LS-DYNA for validation and comparison.With this model,numerical simulation was conducted under various ice thicknesses and upgoing speeds to analyze the instantaneous curves of ice load.The calculation results were statistically analyzed under different working conditions to determine the influence of the factors on the ice load of the cylinder.The study explores the measurement method about ice load of objects vertically breaking through model ice sheet and is expected to provide some fundamental insights into the safety design of underwater structures operating in ice waters.
文摘In the past few decades,the navigation performance of ships and structures in ice-covered waters has not been fully studied,especially the influence of ice mechanical properties on icebreaking ability.Ice bending strength is a key ice parameter for predicting ship ice loads,and accurate ice bending strength is also the key to scaling model tests results to real ship.However,numerical simulation studies on model ice bending strength of ice tanks are often neglected.In this paper,an explicit finite element method model is used to simulate the ice cantilever beam test,and the failure load and bending strength of the ice are obtained.In this model,the Tsai-Wu failure criterion is used as the material constitutive model,and the required simulation parameters are obtained from the model ice test in ice tank.Parameter sensitivity analysis shows that the cantilever beam size of the model ice has a significant effect on the flexural strength.The results show that proper rounding at the root of the cantilever beam is beneficial to reduce stress concentration and obtain more accurate bending strength;the thickness,width and length of the cantilever beam should conform to a certain ratio,and consistent with the ITTC recommended reference.Therefore,the results of this study can promote model ice experiments and numerical studies and provide ice strength data support for ship design and polar ship maneuvering.
文摘In order to understand the influence of bow shape on ice resistance and provide guidelines for hull line design in the early design stage,an investigation of the impact of bow shape on ice resistance for the Arctic LNG carriers is carried out based on semi-empirical methods.Firstly,some typical semi-empirical formulas developed for ice resistance estimation of cargo carriers in different ice conditions are summarized.Then,formulas appropriate for ice resistance estimation of Arctic LNG carriers under different ice conditions are verified according to the result comparison between semi-empirical formulas and experimental tests.The comparison result indicates that the Lindqvist formula is appropriate for ice resistance estimation in level ice conditions,Zuev and Dobrodeev formula for ice resistance estimation in broken ice conditions,and Dobrodeev formula for ice resistance estimation in brash ice conditions.After that,the parameters considered in the selected formulas are summarized,and the influence of critical parameters on ice resistance is analyzed.Some parameters describing the ship's bow shape characteristic like ship breadth,waterline angle and stem angle greatly influence the ice resistance.Ice resistance increases with both the growth of ship breadth under all ice conditions and the growth of stem angle in level ice and broken ice conditions while ice resistance decreases with the development of waterline angle under all ice conditions.Finally,the optimization of the bow shape is discussed,and an optimized bow shape with both a large waterline angle and low stem angle is proposed.The optimized bow shape can decrease ice resistance by 9.9%in the level ice condition and reduce ice resistance by 11.3%in the brash ice condition.
文摘Ships navigating in ice-covered regions will inevitably collide with ice ridges.Compared to other ice bodies,ice ridges exhibit more complicated mechanical behaviors due to the scale and structure characteristics.In this paper,nonlinear finite element method is used to investigate the interaction between a polar ship and an ice ridge.The ice ridge is modelled as elastic-plastic material based on Drucker-Prager yield function,with the consideration of the influence of cohesion,friction angle and material hardening.The material model is developed in LS-DYNA and solved using semi-implicit mapping algorithm.The stress distribution of ice ridge and ship,and the ice load history are evaluated through the simulation of multiple collisions.In addition,parametric analysis is performed to investigate the influence of ridge thickness and impact velocity on the ice load and energy absorption.
文摘In polar regions, floating ice exhibits distinct characteristics across a range of spatial scales. It is well recognized that the irregular geometry of these ice formations markedly influences their dynamic behavior. This study introduces a polyhedral Discrete Element Method (DEM) tailored for polar ice, incorporating the Gilbert-Johnson-Keerthi (GJK) and Expanding Polytope Algorithm (EPA) for contact detection. This approach facilitates the simulation of the drift and collision processes of floating ice, effectively capturing its freezing and fragmentation. Subsequently, the stability and reli ability of this model are validated by uniaxial compression on level ice fields, focusing specifically on the influence of compression strength on deformation resistance. Additionally, clusters of ice floes nav igating through narrow channels are simulated. These studies have qualitatively assessed the effects of Floe Size Distribution (FSD), initial concentration, and circularity on their flow dynamics. The higher power-law exponent values in the FSD, increased circularity, and decreased concentration are each as sociated with accelerated flow in ice floe fields. The simulation results distinctly demonstrate the con siderable impact of sea ice geometry on the movement of clusters, offering valuable insights into the complexities of polar ice dynamics.
