The temperature change of the die surface in practical aluminum alloy die casting process was analyzed,and a 2D model was formulated on the basis of a deep concave round cavity without sliding core to analyze thestres...The temperature change of the die surface in practical aluminum alloy die casting process was analyzed,and a 2D model was formulated on the basis of a deep concave round cavity without sliding core to analyze thestress distributions along the die surface in detail. Equipment was designed to test the thermal state of the die steelin different thermal loading conditions. The results of stress analysis showed that, the value of thermal stress (maximum1.5 GPa) caused in the die filling and die spraying stages was larger than the mechanical stress (maximum 85 MPa)caused in the die locking stage. The results of the thermal check experiment showed that there were three stages ofdie dissolving, and that the stress distribution shown by the samples' cracking routine was close to the die surfacestress analysis.展开更多
1.Introduction Casting accounts for over 90%of magnesium-based alloy applications with die-cast and thixomolded parts dominating.The high strength-to-weight ratio coupled with excellent fluidity,low volumetric latent ...1.Introduction Casting accounts for over 90%of magnesium-based alloy applications with die-cast and thixomolded parts dominating.The high strength-to-weight ratio coupled with excellent fluidity,low volumetric latent heat and heat capacity,reduced cycle times,and low soldering tendencies,all make magnesium alloys excellent choices for die casting applications.Despite these advantages,in recent years,the use of magnesium in die casting applications has been declining.展开更多
This study investigates the formation feasibility of the integrated bottom car body components with dual die casting injection molding technology.During the production of a die-cast super-large one-piece body part wei...This study investigates the formation feasibility of the integrated bottom car body components with dual die casting injection molding technology.During the production of a die-cast super-large one-piece body part weighing over 10,000 t,a thorough comparison and investigation were conducted on the arising issues,using both single and double injection systems.Particular attention was given to meticulously discussing the die casting filling problems and microstructural defects that originated from the filling process.The research findings indicate that the implementation of a double injection system can significantly minimize cold shuts and reduce the solidification time.The effectiveness of this die casting technique was further confirmed by the production of high-quality castings using a scaled model that replicated real casting conditions at a 1:3 ratio,thereby maintaining a one-to-one correspondence in essential aspects.This successful study offers both theoretical insights and practical applications for the production of integrated bottom car bodies utilizing die casting in conjunction with a dual injection system.展开更多
The present status and perspectives of Chinese die-casting market were commented. In 2003, the total output of die castings in the whole country was 708000 tons, in which the outputs of Al-alloy, Zn-alloy, Mg-alloy, C...The present status and perspectives of Chinese die-casting market were commented. In 2003, the total output of die castings in the whole country was 708000 tons, in which the outputs of Al-alloy, Zn-alloy, Mg-alloy, Cu-alloy die castings were 474600 tons, 222000 tons, 5800 tons, 5600 tons, respectively, each accounted for 67%, 31.35%, 0.85%, 0.8% of the total. The annual sale volume of die-casting machines was approximately 1800. And the gross output value of dies approached RMB 38 billion, in which die-casting dies accounted for about 10%. In the die-casting industry of the entire country, the foreign capital enterprises, public-run enterprises, township and village enterprises, private enterprises accounted for over 80% of the total die-casting enterprises. Super huge die-casting groups are forming.展开更多
Die casting machines, dies, die castings, peripheral equipments, die lubricants, raw materials for die casting, melting & holding furnaces, cleaning equipments, etc. were exhibited during the 4th China Internation...Die casting machines, dies, die castings, peripheral equipments, die lubricants, raw materials for die casting, melting & holding furnaces, cleaning equipments, etc. were exhibited during the 4th China International Die Casting Exhibition, which was surveyed in the paper.展开更多
This study presents the development of a Magnesium Alloy Seat Frame(MASF),supported by case studies from automotive original equipment manufacturers.The process covers integrated design,simulation,manufacturing,and te...This study presents the development of a Magnesium Alloy Seat Frame(MASF),supported by case studies from automotive original equipment manufacturers.The process covers integrated design,simulation,manufacturing,and testing,aiming to boost industry confidence in Mg alloy applications.A novel structural design is developed that integrates the headrest with the backrest,achieving a balance between lightweight performance and safety.Structural optimization is guided by stress–strain simulations under diverse conditions within a complete forward development process.Casting simulations are conducted to analyze process characteristics,resulting in a verified MASF yield rate exceeding 90%.The final 9.88 kg MASF represents a 24.6%(3.23 kg)weight reduction versus a steel seat.This research contributes to advancements in defect control technology for large die casting magnesium alloy parts and has broad implications for their application in automotive manufacturing.展开更多
A novel oxide-dispersion-strengthened(ODS)die steel was fabricated by mechanical alloying and hot consolidation.Annealing and quench-tempering treatments both obtained an ultra-fine grain structure(mean size:310-330 n...A novel oxide-dispersion-strengthened(ODS)die steel was fabricated by mechanical alloying and hot consolidation.Annealing and quench-tempering treatments both obtained an ultra-fine grain structure(mean size:310-330 nm)with an ultra-high density of ultra-fine Y-Al-O nano-oxides(number density:~(1-1.5)×10^(23)m^(−3),mean size:5.1-7.2 nm).Prolonged thermal exposure further induced the new,highly dense precipitation of ultra-fine Y-Zr-O nano-oxides.Both nano-oxides tended to be wrapped up with a B2-NiAl nano-shells.Although the quench-tempered sample showed much higher room-temperature strength(yield strength=1393±40 MPa and ultimate tensile strength=1774±11 MPa)and slightly lower elongation(elongation=13.6%±0.6%)than the annealed sample(YS=988±7 MPa,UTS=1490±12 MPa,and EL=15.2%±1.1%),both samples exhibited better strength-ductility synergy at room temperature and much higher thermal stabilities at high temperatures(600-700℃)than all those conventional hot-work die steels,which makes the new ODS steel highly promising for advanced hot-work mold and die applications at high temperatures above 600℃.展开更多
Achieving optimal mechanical performance in high-pressure die-cast(HPDC)Mg-based alloys through experimental methods is both costly and time-intensive due to significant variations in composition.This study leverages ...Achieving optimal mechanical performance in high-pressure die-cast(HPDC)Mg-based alloys through experimental methods is both costly and time-intensive due to significant variations in composition.This study leverages machine learning(ML)techniques to accelerate the development of high-performance Mg-based alloys.Data on alloy composition and mechanical properties were collected from literature sources,focusing on HPDC Mg-based alloys.Six ML models—extra trees,CatBoost,k-nearest neighbors,random forest,gradient boosting,and decision tree—were trained to predict mechanical behavior.Cat Boost yielded the highest prediction accuracy with R^(2) scores of 0.95 for ultimate tensile strength(UTS)and 0.92 for yield strength(YS).Further validation using published datasets reaffirmed its reliability,demonstrating R^(2) values of 0.956(UTS)and 0.936(YS),MAE of 1%and 2.8%,and RMSE of 1%and 3.5%,respectively.Among these,the CatBoost model demonstrated the highest predictive accuracy,outperforming other ML techniques across multiple optimization metrics.展开更多
High-pressure die-cast(HPDC)magnesium(Mg)and aluminum alloys enable vehicle lightweighting while reducing manufacturing costs by simplifying part assembly.The increasing use of super-large castings in electric vehicle...High-pressure die-cast(HPDC)magnesium(Mg)and aluminum alloys enable vehicle lightweighting while reducing manufacturing costs by simplifying part assembly.The increasing use of super-large castings in electric vehicles enhances structural reliability and cost efficiency.However,HPDC Mg alloys face challenges related to casting defects such as porosity,cold shuts,and oxides.These defects influence tensile strength and ductility,depending on their location and size.This study employs finite element(FE)modeling to investigate how a dominant large pore,its position,and the sample size affect the ductility of thin-walled HPDC Mg.Motivated by the ductility variations reported in literature and the experimental findings on AM60 castings,synthetic microstructure-based models are used to assess the effects of different pore sizes and locations.The results indicate the presence of three different regions based on the large pore size and model size:1)a region dominated by the effects of the large pore,2)a plateau region dominated by pore interactions,and 3)a transient region between these two effects.A threshold distance from the sample edge (d≈0.9√D·L)is proposed,within which a large pore can significantly reduce ductility.Additionally,large pores near edges contribute to ductility variations in Mg castings.展开更多
This work managed the extrusion strain path by designing various extrusion die cavities,successfully realizing the texture modification for the ZK60 magnesium alloy.The mechanisms involving the texture dependence on t...This work managed the extrusion strain path by designing various extrusion die cavities,successfully realizing the texture modification for the ZK60 magnesium alloy.The mechanisms involving the texture dependence on the extrusion die cavity as well as their effects on the mechanical properties were emphatically investigated.Results showed that dynamic recrystallization refined the grain size and improved the microstructure homogeneity in the three extrusion specimens,but did not produce too large microstructure differences.By comparison,significant texture differences developed owing to the various extrusion die cavities,which here were mainly reflected in the strong or weak texture components for the c-axes//TD and the c-axes//ND.Such texture differences started from the deformation texture instead of the recrystallization texture whose roles only consisted in dispersing the texture component and reducing the texture intensity.The results from the finite element analysis and the visco-plastic self-consistent model indicated that,in order to accommodate the different strain components induced by the extrusion die cavities,slip systems or tension twinning were activated differently,and this was the critical reason causing the above texture differences.One modified Hall-Petch relationship was adopted to analyze the conjoint effects of grain refinement and texture variation on the yield stress.Additionally,the quantitative results about deformation mechanism activation fractions demonstrated that the texture variations influenced the competition relationships between the twinning induced deformation and the slip dominant deformation,and the former generally produced the lower yield stress and the increasing stage of strain hardening rate,while the latter produced the higher yield stress and the continuous decline of strain hardening rate.展开更多
“遥远的共鸣”,是卡普马吉他全国巡演的主题,同时作为新的指弹专辑名称。主人公亦有两位——Casper Esmann、Eddie van der Meer。二人平日里相距甚远,Casper生活在丹麦,Eddie定居于墨西哥。可即便如此,他们还是走向了同一方舞台,并将...“遥远的共鸣”,是卡普马吉他全国巡演的主题,同时作为新的指弹专辑名称。主人公亦有两位——Casper Esmann、Eddie van der Meer。二人平日里相距甚远,Casper生活在丹麦,Eddie定居于墨西哥。可即便如此,他们还是走向了同一方舞台,并将各自的音乐融合成了一副声音,在纵横交错的情绪流转间交织为彼此的同类。展开更多
修辞学结构论是一种专门研究语篇描写的理论,以篇章结构为研究重点,致力于通过分析语篇结构阐述作者的交际意图在语篇中是如何实现的。通过观察修辞结构关系的类别与分布状况,能够了解语篇的核心思想、连贯特性以及写作特色等基础信息...修辞学结构论是一种专门研究语篇描写的理论,以篇章结构为研究重点,致力于通过分析语篇结构阐述作者的交际意图在语篇中是如何实现的。通过观察修辞结构关系的类别与分布状况,能够了解语篇的核心思想、连贯特性以及写作特色等基础信息。本文将采用修辞结构理论的描述框架对Peter Bichsel的短篇小说Die Tochter的语篇结构进行描述和解释,思考修辞结构理论对于该小说的语篇结构分析能力。根据分析,修辞结构理论可以分析出结构段的中心思想,但是无法把握整篇小说的主旨;修辞结构较多且连接十分紧密,连贯性较强;作者多用背景关系和解释关系进行叙述,先交代背景,再塑造人物,风格细腻。Rhetorical Structure Theory (RST) is a comprehensive set of theories dedicated to describing natural discourse. It emphasizes the structure of texts and aims to elucidate how authors’ communicative intentions are realized through textual analysis. By examining the types and distribution of rhetorical structural relationships, one can gain insights into the central idea, coherence features, writing characteristics, and other fundamental aspects of a text. This paper employs the descriptive framework of Rhetorical Structure Theory to describe and explain the text structure of Peter Bichsel’s short story Die Tochter and reflects on the efficacy of RST in analyzing the textual structure of novels. The analysis reveals that RST can effectively dissect the central idea of individual structural paragraphs but struggles to encapsulate the overarching theme of the entire novel. Furthermore, the rhetorical structures are numerous and tightly interconnected, contributing to a strong sense of coherence. The author frequently utilizes background and explanation relationships in the narration, first establishing the context and then developing the characters, resulting in a nuanced and refined style.展开更多
Nonalcoholic fatty liver disease(NAFLD) has been identified as one of the most prevalent chronic liver disease in adults and children populations. NAFLD is usually associated with the metabolic syndrome(MS), which is ...Nonalcoholic fatty liver disease(NAFLD) has been identified as one of the most prevalent chronic liver disease in adults and children populations. NAFLD is usually associated with the metabolic syndrome(MS), which is chiefly related to insulin resistance and its consequences. Insulin resistance has a crucial role in the pathogenesis of hepatic steatosis and potentially nonalcoholic steatohepatitis(NASH). Because of the contemporary epidemics of MS and obesity, the burden of NAFLD is also expected to rise. Unhealthy diets, such as the so-called western diet, are enriched in fructose, trans-fatty acids and saturated fat and seem to be associated with the development of NAFLD. In human studies, certain dietary sugars, particularly fructose, are used as a substrate for lipogenesis leading to hepatic fatty infiltration, inflammation, and possibly fibrosis. Other investigations have shown that fat consumption especially cholesterol and trans/saturated fatty acids are also steatogenic and seem to increase visceral adiposity. The identification of specific dietary components that favor the development of NASH could be important for the management of this disorder. This review focuses on the effects of different dietary approaches to prevent and treat NAFLD emphasizing the macronutrients and energy composition.展开更多
语义构建离不开认知识解因素。die of和die from可以与同样的表达式搭配,即die of X和die from X。就规约意义而言,die of X通常表达客观的、直接的原因,而die from X通常表达客观的、间接的原因。但在die of X和die from X语义构建过程...语义构建离不开认知识解因素。die of和die from可以与同样的表达式搭配,即die of X和die from X。就规约意义而言,die of X通常表达客观的、直接的原因,而die from X通常表达客观的、间接的原因。但在die of X和die from X语义构建过程中,通过认知识解,客观的、直接的原因会被识解为主观的、间接原因,客观的、间接的原因会被构建为主观的、直接的原因。展开更多
In order to conform to dimensional tolerances, an efficient numerical method, displacement iterative compensation method, based on finite element methodology （FEM） was presented for the wax pattern die profile desig...In order to conform to dimensional tolerances, an efficient numerical method, displacement iterative compensation method, based on finite element methodology （FEM） was presented for the wax pattern die profile design of turbine blades. Casting shrinkages at different positions of the blade which was considered nonlinear thermo-mechanical casting deformations were calculated. Based on the displacement iterative compensation method proposed, the optimized wax pattern die profile can be established. For a A356 alloy blade, substantial reduction in dimensional and shape tolerances was achieved with the developed die shape optimization system. Numerical simulation result obtained by the proposed method shows a good agreement with the result measured experimentally. After four times iterations, compared with the CAD model of turbine blade, the total form error decreases to 0.001 978 mm from the orevious 0.515 815 mm.展开更多
基金Shandong Postdoctoral Innovation Special Fund (No. 200703073)
文摘The temperature change of the die surface in practical aluminum alloy die casting process was analyzed,and a 2D model was formulated on the basis of a deep concave round cavity without sliding core to analyze thestress distributions along the die surface in detail. Equipment was designed to test the thermal state of the die steelin different thermal loading conditions. The results of stress analysis showed that, the value of thermal stress (maximum1.5 GPa) caused in the die filling and die spraying stages was larger than the mechanical stress (maximum 85 MPa)caused in the die locking stage. The results of the thermal check experiment showed that there were three stages ofdie dissolving, and that the stress distribution shown by the samples' cracking routine was close to the die surfacestress analysis.
文摘1.Introduction Casting accounts for over 90%of magnesium-based alloy applications with die-cast and thixomolded parts dominating.The high strength-to-weight ratio coupled with excellent fluidity,low volumetric latent heat and heat capacity,reduced cycle times,and low soldering tendencies,all make magnesium alloys excellent choices for die casting applications.Despite these advantages,in recent years,the use of magnesium in die casting applications has been declining.
基金supported by the National Natural Science Foundation of China(No.52175284)the National Key Research and Development Program of China(Grant No.2022YFB3404201).
文摘This study investigates the formation feasibility of the integrated bottom car body components with dual die casting injection molding technology.During the production of a die-cast super-large one-piece body part weighing over 10,000 t,a thorough comparison and investigation were conducted on the arising issues,using both single and double injection systems.Particular attention was given to meticulously discussing the die casting filling problems and microstructural defects that originated from the filling process.The research findings indicate that the implementation of a double injection system can significantly minimize cold shuts and reduce the solidification time.The effectiveness of this die casting technique was further confirmed by the production of high-quality castings using a scaled model that replicated real casting conditions at a 1:3 ratio,thereby maintaining a one-to-one correspondence in essential aspects.This successful study offers both theoretical insights and practical applications for the production of integrated bottom car bodies utilizing die casting in conjunction with a dual injection system.
文摘The present status and perspectives of Chinese die-casting market were commented. In 2003, the total output of die castings in the whole country was 708000 tons, in which the outputs of Al-alloy, Zn-alloy, Mg-alloy, Cu-alloy die castings were 474600 tons, 222000 tons, 5800 tons, 5600 tons, respectively, each accounted for 67%, 31.35%, 0.85%, 0.8% of the total. The annual sale volume of die-casting machines was approximately 1800. And the gross output value of dies approached RMB 38 billion, in which die-casting dies accounted for about 10%. In the die-casting industry of the entire country, the foreign capital enterprises, public-run enterprises, township and village enterprises, private enterprises accounted for over 80% of the total die-casting enterprises. Super huge die-casting groups are forming.
文摘Die casting machines, dies, die castings, peripheral equipments, die lubricants, raw materials for die casting, melting & holding furnaces, cleaning equipments, etc. were exhibited during the 4th China International Die Casting Exhibition, which was surveyed in the paper.
基金supported in part by the project is supported partly by National Key Research and Development Program of China(no.2022YFB2503504)Chongqing Technology Innovation and Application Development Project(no.CSTB2022TIAD-DEX0011)China Scholarship Council.
文摘This study presents the development of a Magnesium Alloy Seat Frame(MASF),supported by case studies from automotive original equipment manufacturers.The process covers integrated design,simulation,manufacturing,and testing,aiming to boost industry confidence in Mg alloy applications.A novel structural design is developed that integrates the headrest with the backrest,achieving a balance between lightweight performance and safety.Structural optimization is guided by stress–strain simulations under diverse conditions within a complete forward development process.Casting simulations are conducted to analyze process characteristics,resulting in a verified MASF yield rate exceeding 90%.The final 9.88 kg MASF represents a 24.6%(3.23 kg)weight reduction versus a steel seat.This research contributes to advancements in defect control technology for large die casting magnesium alloy parts and has broad implications for their application in automotive manufacturing.
基金support from the National MCF Energy R&D Program of China(No.2018YFE0306100).
文摘A novel oxide-dispersion-strengthened(ODS)die steel was fabricated by mechanical alloying and hot consolidation.Annealing and quench-tempering treatments both obtained an ultra-fine grain structure(mean size:310-330 nm)with an ultra-high density of ultra-fine Y-Al-O nano-oxides(number density:~(1-1.5)×10^(23)m^(−3),mean size:5.1-7.2 nm).Prolonged thermal exposure further induced the new,highly dense precipitation of ultra-fine Y-Zr-O nano-oxides.Both nano-oxides tended to be wrapped up with a B2-NiAl nano-shells.Although the quench-tempered sample showed much higher room-temperature strength(yield strength=1393±40 MPa and ultimate tensile strength=1774±11 MPa)and slightly lower elongation(elongation=13.6%±0.6%)than the annealed sample(YS=988±7 MPa,UTS=1490±12 MPa,and EL=15.2%±1.1%),both samples exhibited better strength-ductility synergy at room temperature and much higher thermal stabilities at high temperatures(600-700℃)than all those conventional hot-work die steels,which makes the new ODS steel highly promising for advanced hot-work mold and die applications at high temperatures above 600℃.
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(2021R1A6A1A10044950)。
文摘Achieving optimal mechanical performance in high-pressure die-cast(HPDC)Mg-based alloys through experimental methods is both costly and time-intensive due to significant variations in composition.This study leverages machine learning(ML)techniques to accelerate the development of high-performance Mg-based alloys.Data on alloy composition and mechanical properties were collected from literature sources,focusing on HPDC Mg-based alloys.Six ML models—extra trees,CatBoost,k-nearest neighbors,random forest,gradient boosting,and decision tree—were trained to predict mechanical behavior.Cat Boost yielded the highest prediction accuracy with R^(2) scores of 0.95 for ultimate tensile strength(UTS)and 0.92 for yield strength(YS).Further validation using published datasets reaffirmed its reliability,demonstrating R^(2) values of 0.956(UTS)and 0.936(YS),MAE of 1%and 2.8%,and RMSE of 1%and 3.5%,respectively.Among these,the CatBoost model demonstrated the highest predictive accuracy,outperforming other ML techniques across multiple optimization metrics.
基金funded by the Department of Energy Office of Vehicle Technologies under the Automotive Lightweighting Materials Program。
文摘High-pressure die-cast(HPDC)magnesium(Mg)and aluminum alloys enable vehicle lightweighting while reducing manufacturing costs by simplifying part assembly.The increasing use of super-large castings in electric vehicles enhances structural reliability and cost efficiency.However,HPDC Mg alloys face challenges related to casting defects such as porosity,cold shuts,and oxides.These defects influence tensile strength and ductility,depending on their location and size.This study employs finite element(FE)modeling to investigate how a dominant large pore,its position,and the sample size affect the ductility of thin-walled HPDC Mg.Motivated by the ductility variations reported in literature and the experimental findings on AM60 castings,synthetic microstructure-based models are used to assess the effects of different pore sizes and locations.The results indicate the presence of three different regions based on the large pore size and model size:1)a region dominated by the effects of the large pore,2)a plateau region dominated by pore interactions,and 3)a transient region between these two effects.A threshold distance from the sample edge (d≈0.9√D·L)is proposed,within which a large pore can significantly reduce ductility.Additionally,large pores near edges contribute to ductility variations in Mg castings.
基金supported by National Natural Science Foundation of China(Grant No.52205344,51925401)Postdoctoral Research Foundation of China(Grant No.2023M732398)+1 种基金National Key Laboratory Foundation of Science and Technology on Materials under Shock and Impact(Grant No.WDZC2023-1)Key Research and Development Program of Shandong Province(Grant No.2023CXPT066).
文摘This work managed the extrusion strain path by designing various extrusion die cavities,successfully realizing the texture modification for the ZK60 magnesium alloy.The mechanisms involving the texture dependence on the extrusion die cavity as well as their effects on the mechanical properties were emphatically investigated.Results showed that dynamic recrystallization refined the grain size and improved the microstructure homogeneity in the three extrusion specimens,but did not produce too large microstructure differences.By comparison,significant texture differences developed owing to the various extrusion die cavities,which here were mainly reflected in the strong or weak texture components for the c-axes//TD and the c-axes//ND.Such texture differences started from the deformation texture instead of the recrystallization texture whose roles only consisted in dispersing the texture component and reducing the texture intensity.The results from the finite element analysis and the visco-plastic self-consistent model indicated that,in order to accommodate the different strain components induced by the extrusion die cavities,slip systems or tension twinning were activated differently,and this was the critical reason causing the above texture differences.One modified Hall-Petch relationship was adopted to analyze the conjoint effects of grain refinement and texture variation on the yield stress.Additionally,the quantitative results about deformation mechanism activation fractions demonstrated that the texture variations influenced the competition relationships between the twinning induced deformation and the slip dominant deformation,and the former generally produced the lower yield stress and the increasing stage of strain hardening rate,while the latter produced the higher yield stress and the continuous decline of strain hardening rate.
文摘“遥远的共鸣”,是卡普马吉他全国巡演的主题,同时作为新的指弹专辑名称。主人公亦有两位——Casper Esmann、Eddie van der Meer。二人平日里相距甚远,Casper生活在丹麦,Eddie定居于墨西哥。可即便如此,他们还是走向了同一方舞台,并将各自的音乐融合成了一副声音,在纵横交错的情绪流转间交织为彼此的同类。
文摘修辞学结构论是一种专门研究语篇描写的理论,以篇章结构为研究重点,致力于通过分析语篇结构阐述作者的交际意图在语篇中是如何实现的。通过观察修辞结构关系的类别与分布状况,能够了解语篇的核心思想、连贯特性以及写作特色等基础信息。本文将采用修辞结构理论的描述框架对Peter Bichsel的短篇小说Die Tochter的语篇结构进行描述和解释,思考修辞结构理论对于该小说的语篇结构分析能力。根据分析,修辞结构理论可以分析出结构段的中心思想,但是无法把握整篇小说的主旨;修辞结构较多且连接十分紧密,连贯性较强;作者多用背景关系和解释关系进行叙述,先交代背景,再塑造人物,风格细腻。Rhetorical Structure Theory (RST) is a comprehensive set of theories dedicated to describing natural discourse. It emphasizes the structure of texts and aims to elucidate how authors’ communicative intentions are realized through textual analysis. By examining the types and distribution of rhetorical structural relationships, one can gain insights into the central idea, coherence features, writing characteristics, and other fundamental aspects of a text. This paper employs the descriptive framework of Rhetorical Structure Theory to describe and explain the text structure of Peter Bichsel’s short story Die Tochter and reflects on the efficacy of RST in analyzing the textual structure of novels. The analysis reveals that RST can effectively dissect the central idea of individual structural paragraphs but struggles to encapsulate the overarching theme of the entire novel. Furthermore, the rhetorical structures are numerous and tightly interconnected, contributing to a strong sense of coherence. The author frequently utilizes background and explanation relationships in the narration, first establishing the context and then developing the characters, resulting in a nuanced and refined style.
基金Supported by The Fundacao de Amparo à Pesquisa do Estado de Minas Gerais(FAPEMIG)
文摘Nonalcoholic fatty liver disease(NAFLD) has been identified as one of the most prevalent chronic liver disease in adults and children populations. NAFLD is usually associated with the metabolic syndrome(MS), which is chiefly related to insulin resistance and its consequences. Insulin resistance has a crucial role in the pathogenesis of hepatic steatosis and potentially nonalcoholic steatohepatitis(NASH). Because of the contemporary epidemics of MS and obesity, the burden of NAFLD is also expected to rise. Unhealthy diets, such as the so-called western diet, are enriched in fructose, trans-fatty acids and saturated fat and seem to be associated with the development of NAFLD. In human studies, certain dietary sugars, particularly fructose, are used as a substrate for lipogenesis leading to hepatic fatty infiltration, inflammation, and possibly fibrosis. Other investigations have shown that fat consumption especially cholesterol and trans/saturated fatty acids are also steatogenic and seem to increase visceral adiposity. The identification of specific dietary components that favor the development of NASH could be important for the management of this disorder. This review focuses on the effects of different dietary approaches to prevent and treat NAFLD emphasizing the macronutrients and energy composition.
文摘语义构建离不开认知识解因素。die of和die from可以与同样的表达式搭配,即die of X和die from X。就规约意义而言,die of X通常表达客观的、直接的原因,而die from X通常表达客观的、间接的原因。但在die of X和die from X语义构建过程中,通过认知识解,客观的、直接的原因会被识解为主观的、间接原因,客观的、间接的原因会被构建为主观的、直接的原因。
基金Project (2008ZE53042) supported by National Aerospace Science Foundation of China
文摘In order to conform to dimensional tolerances, an efficient numerical method, displacement iterative compensation method, based on finite element methodology （FEM） was presented for the wax pattern die profile design of turbine blades. Casting shrinkages at different positions of the blade which was considered nonlinear thermo-mechanical casting deformations were calculated. Based on the displacement iterative compensation method proposed, the optimized wax pattern die profile can be established. For a A356 alloy blade, substantial reduction in dimensional and shape tolerances was achieved with the developed die shape optimization system. Numerical simulation result obtained by the proposed method shows a good agreement with the result measured experimentally. After four times iterations, compared with the CAD model of turbine blade, the total form error decreases to 0.001 978 mm from the orevious 0.515 815 mm.
