In track and field sports,the 100-meter race is an extremely intense sport that requires effective training of athletes’core strength.From the perspective of adolescents,in order to enhance core strength,it is necess...In track and field sports,the 100-meter race is an extremely intense sport that requires effective training of athletes’core strength.From the perspective of adolescents,in order to enhance core strength,it is necessary to effectively fix the pelvic position in the process of exercise,so that the core stability,balance,and coordination of athletes can be improved.The training process of the 100-meter event is mainly an anaerobic metabolic exercise,it is necessary to ensure that athletes maintain a high level of physical readiness during the exercises and concentrate highly on their core strength,so that they can achieve excellent results.This paper analyzes the core strength training for the 100-meter event in track and field sports,discusses its importance,and puts forward specific training methods,hoping to provide guidelines for relevant researchers.展开更多
With the popularity of tennis in the sports world,more and more beginners are joining this sport.However,for beginners,how to improve motor skills and game performance is still an important issue.Core strength trainin...With the popularity of tennis in the sports world,more and more beginners are joining this sport.However,for beginners,how to improve motor skills and game performance is still an important issue.Core strength training has potential as a potential adjunct to improve overall fitness and skill in athletes.Therefore,this research aimed to explore the potential impact of core strength training on the motor skills of tennis beginners to provide better training strategies and guidance for coaches and athletes.展开更多
Water soluble cores(WSCs) have been widely applied in manufacture of complex metal components with hollow configurations or internal channels. However, the WSCs without any additons have low tensile strength and low h...Water soluble cores(WSCs) have been widely applied in manufacture of complex metal components with hollow configurations or internal channels. However, the WSCs without any additons have low tensile strength and low humidity resistance. The purpose of this study is to prepare a water-soluble potassium carbonate sand core with addition of kaolin by the hot-temping method. The effects of kaolin on tensile strength, humidity resistance, fracture mechanism, as well as the gas evolution and collapsibility of WSCs were investigated. Results show that both the crystal morphology and the fracture mechanism of the inorganic salt are changed under the participation of kaolin, contributing to the increase of the tensile strength and the humidity resistance of the core. With the addition of 3wt.% kaolin, the tensile strength could be increased by a factor of 2, reached 1.50 MPa and the hygroscopic rate could be decreased by 14%, achieved 0.559%(after stored for 8 h), respectively. As the addition amount of kaolin increases from 0wt.% to 3wt.%, the main fracture mechanism changes from a adhesive to a cohesive fracture mechanism. The water-soluble potassium carbonate core obtained has the low gas evolution and excellent collapsibility, which makes it suitable for casting low melting metal with complex cavities and crooked channels.展开更多
The Sonreb and Core (SRC) combined method is proposed to assess the concrete compression strength of mass concrete structures.Artificial neural network is employed together with the SRC combined method to obtain the o...The Sonreb and Core (SRC) combined method is proposed to assess the concrete compression strength of mass concrete structures.Artificial neural network is employed together with the SRC combined method to obtain the optimal core number.The artificial neural network is trained based on data from different testing methods.The procedure of using artificial neural network to assess the concrete strength is described.It proves that the SRC combined method is superior in many aspects and artificial the presented neural network has a high efficiency and reliability.The combined method using artificial intelligence is promising in the strength assessment of mass concrete structures such as the dam,the anchor of the suspension bridge,etc.展开更多
By using Visual C++, a model with post processing was carried out to simulate the temperature and strength distributions of the mold(core). The results are shown in 256 color graphic mode. With this model, the tempera...By using Visual C++, a model with post processing was carried out to simulate the temperature and strength distributions of the mold(core). The results are shown in 256 color graphic mode. With this model, the temperature and strength distributions of the mold(core) both in case of heating process for core in the furnace and solidification process for a thin wall aluminum alloy casting in the mold(core) are numerically simulated. The results show that the temperature and strength distributions of the mold(core) were uneven because the thermal conductivity of the resin sand was much small. This study laid a basis for the optimum design of the mold(core) properties. [展开更多
Precast prestressed Hollow Core Slabs (HCS), are one of the famous and widely used slabs for concrete structures all over the world and widely implemented in the Middle East. HCS are used in industrial, commercial, re...Precast prestressed Hollow Core Slabs (HCS), are one of the famous and widely used slabs for concrete structures all over the world and widely implemented in the Middle East. HCS are used in industrial, commercial, residential buildings, as well as, in the parking structures. This paper succeeded to present new special details for deep HCS to enhance and strengthen the web shear strength capacity of HCS 400 and 500 mm depths respectively at the open parking area. This is subjected to heavy truck wheel loads so as to achieve the LRFD Code’s requirements. However, it is noticed many web shear cracks of HCS are used at parking area at many projects in Gulf Region. On the other hand, ACI318-14 permits no shear reinforcement in prestressed HCS thickness of less than 12.5 in (320 mm). The paper presents experimental tests program, to verify the numerical finite element of deep HCS under maximum design uniform loads, in addition to the new strengthening techniques. New strengthening techniques succeed to enhance the web shear capacity by significant percentage, due to the new details for HCS 400 by 68% up to 256% increasing of the web shear capacity compared to the ordinary HCS section. Also, HCS 500 shear capacity is enhanced with different percentages of strengthening techniques by 55%, up to 197% based on the different cases of strengthening. Furthermore enhancing deep HCS shear performance;the new techniques have an advantage of an easy execution at the site;casting with structural topping, otherwise the preparation can be done in precast factory before site handover, which saves time and cost compared to the others traditional strengthening techniques.展开更多
地理学研究可持续发展旨在构建人与自然命运共同体,实现人类社会的永续发展.该文依托CNKI数据库、读秀资源库以及Web of Science数据库,限定主题词为“可持续”“可持续发展”和“可持续性”,采用CiteSpace软件对1994—2021年中国地理...地理学研究可持续发展旨在构建人与自然命运共同体,实现人类社会的永续发展.该文依托CNKI数据库、读秀资源库以及Web of Science数据库,限定主题词为“可持续”“可持续发展”和“可持续性”,采用CiteSpace软件对1994—2021年中国地理学者“可持续”研究的核心力量、重点区域与重要领域进行文献计量分析,结果表明:1)中国地理学者“可持续”研究的过程可分为快速兴起(1994—2001年)、稳定发展(2002—2011年)和整固深化(2012—2021年)三个阶段.2)中国开展“可持续”研究的地理学者多达624位,主要是自然地理学者和人文地理学者,研究机构多达258个,主要是中国科学院所属地理单位,机构间合作具有空间邻近性,机构空间分布具有东、中、西梯度分异性;中国地理学者“可持续”研究的对象区域以地方行政区域为主,服务国家重大区域发展战略的特色鲜明.3)中国地理学者“可持续”研究的重点领域有资源可持续利用、生态环境保护与建设、农业可持续发展、旅游可持续发展、可持续发展教育、可持续发展伦理、消除贫困与可持续生计、区域人地关系协调、城市可持续发展、农村可持续发展、区域可持续发展战略、区域可持续发展评价等.4)未来中国地理学者的“可持续”研究应在可持续发展专业人才培养、可持续发展理论体系完善、可持续发展研究领域拓展、可持续发展服务能力提升等方面下功夫.展开更多
文摘In track and field sports,the 100-meter race is an extremely intense sport that requires effective training of athletes’core strength.From the perspective of adolescents,in order to enhance core strength,it is necessary to effectively fix the pelvic position in the process of exercise,so that the core stability,balance,and coordination of athletes can be improved.The training process of the 100-meter event is mainly an anaerobic metabolic exercise,it is necessary to ensure that athletes maintain a high level of physical readiness during the exercises and concentrate highly on their core strength,so that they can achieve excellent results.This paper analyzes the core strength training for the 100-meter event in track and field sports,discusses its importance,and puts forward specific training methods,hoping to provide guidelines for relevant researchers.
文摘With the popularity of tennis in the sports world,more and more beginners are joining this sport.However,for beginners,how to improve motor skills and game performance is still an important issue.Core strength training has potential as a potential adjunct to improve overall fitness and skill in athletes.Therefore,this research aimed to explore the potential impact of core strength training on the motor skills of tennis beginners to provide better training strategies and guidance for coaches and athletes.
基金supported by the National Natural Science Foundation of China(No.51405002)
文摘Water soluble cores(WSCs) have been widely applied in manufacture of complex metal components with hollow configurations or internal channels. However, the WSCs without any additons have low tensile strength and low humidity resistance. The purpose of this study is to prepare a water-soluble potassium carbonate sand core with addition of kaolin by the hot-temping method. The effects of kaolin on tensile strength, humidity resistance, fracture mechanism, as well as the gas evolution and collapsibility of WSCs were investigated. Results show that both the crystal morphology and the fracture mechanism of the inorganic salt are changed under the participation of kaolin, contributing to the increase of the tensile strength and the humidity resistance of the core. With the addition of 3wt.% kaolin, the tensile strength could be increased by a factor of 2, reached 1.50 MPa and the hygroscopic rate could be decreased by 14%, achieved 0.559%(after stored for 8 h), respectively. As the addition amount of kaolin increases from 0wt.% to 3wt.%, the main fracture mechanism changes from a adhesive to a cohesive fracture mechanism. The water-soluble potassium carbonate core obtained has the low gas evolution and excellent collapsibility, which makes it suitable for casting low melting metal with complex cavities and crooked channels.
基金Sponsored by the Priority Academic Program Development Foundation of Jiangsu Higher Education Institute(Grant No. CE01-3)the NSFC for Outstanding Youth Fund (Grant No. 50725828),the NSFC for Young Scholars (Grant No. 50908046)+1 种基金the Ph. D. Programs Foundation of Ministry of Education of China (Grant No. 200802861012)the Basic Scientific & Research Fund of Southeast University (Grant No. Seucx201106)
文摘The Sonreb and Core (SRC) combined method is proposed to assess the concrete compression strength of mass concrete structures.Artificial neural network is employed together with the SRC combined method to obtain the optimal core number.The artificial neural network is trained based on data from different testing methods.The procedure of using artificial neural network to assess the concrete strength is described.It proves that the SRC combined method is superior in many aspects and artificial the presented neural network has a high efficiency and reliability.The combined method using artificial intelligence is promising in the strength assessment of mass concrete structures such as the dam,the anchor of the suspension bridge,etc.
文摘By using Visual C++, a model with post processing was carried out to simulate the temperature and strength distributions of the mold(core). The results are shown in 256 color graphic mode. With this model, the temperature and strength distributions of the mold(core) both in case of heating process for core in the furnace and solidification process for a thin wall aluminum alloy casting in the mold(core) are numerically simulated. The results show that the temperature and strength distributions of the mold(core) were uneven because the thermal conductivity of the resin sand was much small. This study laid a basis for the optimum design of the mold(core) properties. [
文摘Precast prestressed Hollow Core Slabs (HCS), are one of the famous and widely used slabs for concrete structures all over the world and widely implemented in the Middle East. HCS are used in industrial, commercial, residential buildings, as well as, in the parking structures. This paper succeeded to present new special details for deep HCS to enhance and strengthen the web shear strength capacity of HCS 400 and 500 mm depths respectively at the open parking area. This is subjected to heavy truck wheel loads so as to achieve the LRFD Code’s requirements. However, it is noticed many web shear cracks of HCS are used at parking area at many projects in Gulf Region. On the other hand, ACI318-14 permits no shear reinforcement in prestressed HCS thickness of less than 12.5 in (320 mm). The paper presents experimental tests program, to verify the numerical finite element of deep HCS under maximum design uniform loads, in addition to the new strengthening techniques. New strengthening techniques succeed to enhance the web shear capacity by significant percentage, due to the new details for HCS 400 by 68% up to 256% increasing of the web shear capacity compared to the ordinary HCS section. Also, HCS 500 shear capacity is enhanced with different percentages of strengthening techniques by 55%, up to 197% based on the different cases of strengthening. Furthermore enhancing deep HCS shear performance;the new techniques have an advantage of an easy execution at the site;casting with structural topping, otherwise the preparation can be done in precast factory before site handover, which saves time and cost compared to the others traditional strengthening techniques.
文摘地理学研究可持续发展旨在构建人与自然命运共同体,实现人类社会的永续发展.该文依托CNKI数据库、读秀资源库以及Web of Science数据库,限定主题词为“可持续”“可持续发展”和“可持续性”,采用CiteSpace软件对1994—2021年中国地理学者“可持续”研究的核心力量、重点区域与重要领域进行文献计量分析,结果表明:1)中国地理学者“可持续”研究的过程可分为快速兴起(1994—2001年)、稳定发展(2002—2011年)和整固深化(2012—2021年)三个阶段.2)中国开展“可持续”研究的地理学者多达624位,主要是自然地理学者和人文地理学者,研究机构多达258个,主要是中国科学院所属地理单位,机构间合作具有空间邻近性,机构空间分布具有东、中、西梯度分异性;中国地理学者“可持续”研究的对象区域以地方行政区域为主,服务国家重大区域发展战略的特色鲜明.3)中国地理学者“可持续”研究的重点领域有资源可持续利用、生态环境保护与建设、农业可持续发展、旅游可持续发展、可持续发展教育、可持续发展伦理、消除贫困与可持续生计、区域人地关系协调、城市可持续发展、农村可持续发展、区域可持续发展战略、区域可持续发展评价等.4)未来中国地理学者的“可持续”研究应在可持续发展专业人才培养、可持续发展理论体系完善、可持续发展研究领域拓展、可持续发展服务能力提升等方面下功夫.
