The impact value (AK) measured with classic impact experiment of mechanical properties is a normal index from the five important basic mechanical properties for engineering, but it still has no definite physical meani...The impact value (AK) measured with classic impact experiment of mechanical properties is a normal index from the five important basic mechanical properties for engineering, but it still has no definite physical meaning. By use of the advanced impact experimental machine, the load-deflection signals under impact loading have been measured. According to the load-deflection curve of 30CrMnSiA steel obtained by this method, the AK value could be divided into the elastic deformation work, the plastic deformation work, the crack forming work, the work of crack propagation and the work of unstable crack propagation. Therefore, we can obtain the expression for the continuous changing of stress and strain under impact load. In this experiment, specimens with three different breaches, U type, V type and linear grooving, are used and the dynamic fracture toughness value (KDIC) of 30CrMnSiA steel is treated and calculated which follows the measuring method of material static fracture toughness, as ASTM E399. The experimental results verify that these impact specimens with three different breaches are satisfactory for plane strain relation under impact load. For high strength 30CrMnSiA steel, the maximum load of load-deflection curve under impact load can represent the unstable propagation load of crack. The precision of the calculated fracture toughness (KDIC) meets the engineering requirement of materials.展开更多
The formation of the Tongyu gold deposit, controlled by regional polyphase deformation-metamorphism.is closely related to the regional composite antiform-shear slip fracture zone. Late-stage reworking of theTaihua Gro...The formation of the Tongyu gold deposit, controlled by regional polyphase deformation-metamorphism.is closely related to the regional composite antiform-shear slip fracture zone. Late-stage reworking of theTaihua Group accounts for the enrichment of ore substances. It is a typical syntectonic gold deposit. The formation and evolution of the deposit involved four stages: (Ⅰ) the state of preparation of ore sub-stances, in which primary source beds originated: (Ⅱ) the stage of remobilization of ore substances, in whichregional progressive metamorphism and migmatization and thermodynamic-chemical differentiation led toremobilization of gold and its initial local concentration: (Ⅲ) the stage of gold deposit formation, in which re-gional folding produced concordant and cross shear-slip fractures and under the dynamic action gold was sepa-rated and migrated in a certain direction and concentrated to form a gold deposit: (Ⅳ) the stage ofsuperpositon, reworking and exposure of orebodies, in which the block uplifted and the deposit againunderwent reworking through faulting and mechanical differentiation.Thermodynamic mineralization played adominant role in the formation of the deposit.展开更多
In this paper. it is demonstrated that there exist marine horizons in the upper part of the lower subcycleand the upper subeycle of the Kizilsu Group in Xinjiang. based on new evidence of authigenic glauconite.boron c...In this paper. it is demonstrated that there exist marine horizons in the upper part of the lower subcycleand the upper subeycle of the Kizilsu Group in Xinjiang. based on new evidence of authigenic glauconite.boron content. carbon and oxygen stablc isotopic analyses. and lithological and sedimentary features. The up-per part of the lower subeycle is the lowermost marine horizon of the Cretaceous in the western Tarim Basin,which is inferred to be of Barremian age.展开更多
In this paper, the distribution characteristics of the breaking wave current and suspended load transport in the surf zone are discussed in main. Based on the measured data of the waves, the form of breaking wave, the...In this paper, the distribution characteristics of the breaking wave current and suspended load transport in the surf zone are discussed in main. Based on the measured data of the waves, the form of breaking wave, the breaking wave current and the sediment concentration of suspended load in the offshore surf zone near Nouakchott, the Islamic Republic of Mauritania, the author has analized the law governing the distribution of longshore current and sediment concentration of suspended load by means of statistical method, and presented a calculation method for the longshore sediment transport in offshore surf zone.展开更多
Reading is really a complex of skills and not a single one. It is very popular these days to try to improve reading skills. One sees many essays m newspapers and elsewhere for courses, materias and equipment designed ...Reading is really a complex of skills and not a single one. It is very popular these days to try to improve reading skills. One sees many essays m newspapers and elsewhere for courses, materias and equipment designed to improve reading rate and comprehension. Most often the emphasis is on reading rate, not on specific comprehention skills. Most of the time is also spent on increasing reading rate, not on good comprehension. I consider neither of them should be overmphasized at the expense of the other.展开更多
1 Changes in College-English TeachingMethodology:a NecessityThere used to be an idea among some people thatteaching College-English for non-English-major stu-dents was much easier than for English-major stu-dents.Ther...1 Changes in College-English TeachingMethodology:a NecessityThere used to be an idea among some people thatteaching College-English for non-English-major stu-dents was much easier than for English-major stu-dents.There might have been something in this pointof view then,but things are definitely undergoing achange now.If we make a comparison between theNew Teaching Program for Non-English-major Col-lege Students and the Teaching Program for展开更多
"Imitation Antique"Not Worthy of RecommendationWang Zhiming(Senior Planner,Director.Institute of Theoretical Research and HistoricCity Studies,China Academy of Urban Planning and Design)
WHEN the Beijing Evening News carried her essay Facing the World Without Makeup, (also carried in our May 1993 issue), Bi Shumin never expected it to arouse readers’ interest, especially women readers. Bi Shumin, an ...WHEN the Beijing Evening News carried her essay Facing the World Without Makeup, (also carried in our May 1993 issue), Bi Shumin never expected it to arouse readers’ interest, especially women readers. Bi Shumin, an influential writer展开更多
文摘The impact value (AK) measured with classic impact experiment of mechanical properties is a normal index from the five important basic mechanical properties for engineering, but it still has no definite physical meaning. By use of the advanced impact experimental machine, the load-deflection signals under impact loading have been measured. According to the load-deflection curve of 30CrMnSiA steel obtained by this method, the AK value could be divided into the elastic deformation work, the plastic deformation work, the crack forming work, the work of crack propagation and the work of unstable crack propagation. Therefore, we can obtain the expression for the continuous changing of stress and strain under impact load. In this experiment, specimens with three different breaches, U type, V type and linear grooving, are used and the dynamic fracture toughness value (KDIC) of 30CrMnSiA steel is treated and calculated which follows the measuring method of material static fracture toughness, as ASTM E399. The experimental results verify that these impact specimens with three different breaches are satisfactory for plane strain relation under impact load. For high strength 30CrMnSiA steel, the maximum load of load-deflection curve under impact load can represent the unstable propagation load of crack. The precision of the calculated fracture toughness (KDIC) meets the engineering requirement of materials.
文摘The formation of the Tongyu gold deposit, controlled by regional polyphase deformation-metamorphism.is closely related to the regional composite antiform-shear slip fracture zone. Late-stage reworking of theTaihua Group accounts for the enrichment of ore substances. It is a typical syntectonic gold deposit. The formation and evolution of the deposit involved four stages: (Ⅰ) the state of preparation of ore sub-stances, in which primary source beds originated: (Ⅱ) the stage of remobilization of ore substances, in whichregional progressive metamorphism and migmatization and thermodynamic-chemical differentiation led toremobilization of gold and its initial local concentration: (Ⅲ) the stage of gold deposit formation, in which re-gional folding produced concordant and cross shear-slip fractures and under the dynamic action gold was sepa-rated and migrated in a certain direction and concentrated to form a gold deposit: (Ⅳ) the stage ofsuperpositon, reworking and exposure of orebodies, in which the block uplifted and the deposit againunderwent reworking through faulting and mechanical differentiation.Thermodynamic mineralization played adominant role in the formation of the deposit.
文摘In this paper. it is demonstrated that there exist marine horizons in the upper part of the lower subcycleand the upper subeycle of the Kizilsu Group in Xinjiang. based on new evidence of authigenic glauconite.boron content. carbon and oxygen stablc isotopic analyses. and lithological and sedimentary features. The up-per part of the lower subeycle is the lowermost marine horizon of the Cretaceous in the western Tarim Basin,which is inferred to be of Barremian age.
文摘In this paper, the distribution characteristics of the breaking wave current and suspended load transport in the surf zone are discussed in main. Based on the measured data of the waves, the form of breaking wave, the breaking wave current and the sediment concentration of suspended load in the offshore surf zone near Nouakchott, the Islamic Republic of Mauritania, the author has analized the law governing the distribution of longshore current and sediment concentration of suspended load by means of statistical method, and presented a calculation method for the longshore sediment transport in offshore surf zone.
文摘Reading is really a complex of skills and not a single one. It is very popular these days to try to improve reading skills. One sees many essays m newspapers and elsewhere for courses, materias and equipment designed to improve reading rate and comprehension. Most often the emphasis is on reading rate, not on specific comprehention skills. Most of the time is also spent on increasing reading rate, not on good comprehension. I consider neither of them should be overmphasized at the expense of the other.
文摘1 Changes in College-English TeachingMethodology:a NecessityThere used to be an idea among some people thatteaching College-English for non-English-major stu-dents was much easier than for English-major stu-dents.There might have been something in this pointof view then,but things are definitely undergoing achange now.If we make a comparison between theNew Teaching Program for Non-English-major Col-lege Students and the Teaching Program for
文摘"Imitation Antique"Not Worthy of RecommendationWang Zhiming(Senior Planner,Director.Institute of Theoretical Research and HistoricCity Studies,China Academy of Urban Planning and Design)
文摘WHEN the Beijing Evening News carried her essay Facing the World Without Makeup, (also carried in our May 1993 issue), Bi Shumin never expected it to arouse readers’ interest, especially women readers. Bi Shumin, an influential writer
