To improve the cutting performance of an hourglass worm gear hob and the accuracy of the resulting worm gear,the rake angles of the teeth on the pitch circle should be reduced.A method of forming the spiral flutes by ...To improve the cutting performance of an hourglass worm gear hob and the accuracy of the resulting worm gear,the rake angles of the teeth on the pitch circle should be reduced.A method of forming the spiral flutes by using a variable transmission ratio was developed.This method ensures that the rake angles on the indexing torus of each tooth are approximately 0°.Based on the gear meshing theory and the hourglass worm forming method,the discretization mathematical model of the rake face of a planar double enveloping worm gear hob was established by using cylindrical generating surface,and the feed parameters for machining the rake face for a variable transmission ratio were obtained.The spiral flute was simulated and the hob was machined on a four axis CNC milling machine.A contourgraph was used to measure the rake angle.The measurement results showed that the proposed method can reduce the absolute value of the rake angle on both sides of the cutting teeth,which can be used for machining the spiral flute rake face of an hourglass worm gear hob.展开更多
Spin effect of the small diameter shaped charge results in the centrifugal stress during the jet stretching process. Consequently, the jet scatters, which deceases the jet penetration capability. In the present study,...Spin effect of the small diameter shaped charge results in the centrifugal stress during the jet stretching process. Consequently, the jet scatters, which deceases the jet penetration capability. In the present study, a multi-section method was proposed to design the spin-compensation liner. The spincompensation rate(SCR) of the liner was defined as the specific angular velocity that a fluted liner can offset. Based on the plain stress theory, SPH numerical method was applied to study the converging process of the 2D fluted structure. The spin-compensation mechanism of the fluted structure was illustrated. Then, nine cross sections were chosen along the liner axis equidistantly. On each of the section, a 2D fluted structure was designed to offset a given initial angular velocity. After, the optimized fluted structures were integrated into a 3D fluted liner. Jet appearances of the normal liner and the fluted liners under different initial angular velocities were compared, which verifies the practicality of the multi-sectional method. The multi-section optimization method provides a new efficient method of designing the shaped charge liner for a specific usage.展开更多
Arthur Miller's Death of a Salesman takes advantage of the flute music to strengthen the atmosphere of stage, thus acoustically making people immerse the scene of the drama. The paper explores the conflicts and co...Arthur Miller's Death of a Salesman takes advantage of the flute music to strengthen the atmosphere of stage, thus acoustically making people immerse the scene of the drama. The paper explores the conflicts and connections in this drama through the flute music, such as work and family, agriculture and business, work and family.展开更多
Fluted pumpkin(FP;Telfairia occidentalis)is an edible vegetable,grown in West Africa,that is used in traditional medicine for its regulatory effects on the male gonads.Scientific articles concerning the effects of FP ...Fluted pumpkin(FP;Telfairia occidentalis)is an edible vegetable,grown in West Africa,that is used in traditional medicine for its regulatory effects on the male gonads.Scientific articles concerning the effects of FP were identified by searching PubMed,PubChem,Scopus,Springer,ResearchGate,Google Scholar and Web of Science;this literature was to better understand the effects of FP seed(FPS)and leaf(FPL)extracts on the testes.Data showed that in experimental animals extracts of FPL and FPS at 1/100 of the lethal dose promoted testis regeneration and improved testosterone concentration and sperm quality,while at higher doses they had antifertility effects.Several extracts of FPS and FPL,including ethanol,aqueous,methanol and hydroethanolic,had protective effects on the testes of study animals at lower doses(>50 mg/kg body weight),but at higher doses(>200 mg/kg body weight)they inhibited hormone synthesis,sperm quality and histomorphological structure,under both normal and disease conditions.The posttreatment effects of FPS on the gonads were reversible in young mature rats and FPS had slight systemic toxic effects.Although,there are inconsistencies in some of the published results,the current evidence suggests that FPS and FPL have both profertility and reversible antifertility effects in experimental animals.展开更多
The manafacturing theory proposed in this paper is composed of the se-lection of the machining type(motions and adjustments)and the determination of thefunctions of motion parameters.The paper shows that the special r...The manafacturing theory proposed in this paper is composed of the se-lection of the machining type(motions and adjustments)and the determination of thefunctions of motion parameters.The paper shows that the special revolving tools withconstant spiral angled egdes can be ground in the[x y (?)]or[x y z (?)]systembased on the conjugate theory and differential geometry.The functions of motion pa-rameters in these two systems are deduced.展开更多
Based on the principles of differential geometry and kinematics, a mathematical model is developed to describe the grinding wheel axial cross-section with the radial cross-section of the flute in a given drill under t...Based on the principles of differential geometry and kinematics, a mathematical model is developed to describe the grinding wheel axial cross-section with the radial cross-section of the flute in a given drill under the basic engagement condition between the generating flute and the generated grinding wheel （or disk milling tool）. The mathematical model is good for the flute in the radial cross-section consisting of three arcs. Furthermore, a CAD system is also developed to represent the axial cross-section of the grinding wheel （or disk milling tool）. With the system, the grinding wheel （or disk milling tool） axial cross-section that corresponds to the three-arc flute cross section can be conveniently simulated. Through the grinding experiment of drill flutes, the method and the CAD system are proved to be feasible and reasonable.展开更多
Twist drill flute profile design is necessary in order to determine the required grinding wheel profile for a flute production. An accurate drill flute profile design is generated for two-flute conical twist drills us...Twist drill flute profile design is necessary in order to determine the required grinding wheel profile for a flute production. An accurate drill flute profile design is generated for two-flute conical twist drills using analytical equations to generate a drill flute profile design needed for the production of twist drills with straight lips. The required grinding wheel profile for a flute production was expressed in digitized form as well as in terms of two curve-fitted circular arcs. The drill flute profile geometry can never be precisely generated when required grinding wheel profile is represented by two circular arcs and the generated flute profile is just a very good approximation of the design flute profile. A CAD （computer aided design） software has been developed using MATLAB to determine the required grinding wheel profile for generating a given drill flute profile design.展开更多
The flute is a kind of typical foreign musical instruments, as members of the group of typical modern instruments, flute sound very feminine, emotion is extremely rich, it is very convenient to carry and also more nim...The flute is a kind of typical foreign musical instruments, as members of the group of typical modern instruments, flute sound very feminine, emotion is extremely rich, it is very convenient to carry and also more nimble, easy to learn all these advantages make flute study inspire more young people interested in, but unfortunately is currently in the process of flute teaching in colleges and universities in our country, Teaching scale is not big enough, said the creation of works of art is not prominent, and that's a big gap between western countries and China in the field of teaching still need to continuously reform and exploration of teaching method innovation to the flute teaching and combining the national music, can let the flute in the growing of China's historical and cultural soil, was developed. Based on this, this paper mainly discusses the reform and innovation strategies of university site teaching. For reference by relevant staff.展开更多
Because of its special timbre, the flute is the preference of the ancient people in the court, even there are a lot of the imperial court musicians use the flute to perform, the flute is an important and indispensable...Because of its special timbre, the flute is the preference of the ancient people in the court, even there are a lot of the imperial court musicians use the flute to perform, the flute is an important and indispensable good instrument in our country, its heritage also brought to the attention of the people, teaching investigation of flute, flute skill teaching have been mature enough at present. However, there are still some deficiencies in the cultivation of students' aesthetics, especially in the lack of subjective aesthetic action. Based on this, this paper mainly discusses the cultivation strategy of flute teaching aesthetic ability in colleges and universities. For reference by relevant staff.展开更多
Bamboo flute has a deep history in our country, is the inheritance of Chinese national culture, players can use bamboo flute playing a variety of types of repertoire, and production of bamboo flute itself were lighter...Bamboo flute has a deep history in our country, is the inheritance of Chinese national culture, players can use bamboo flute playing a variety of types of repertoire, and production of bamboo flute itself were lighter, very convenient to carry, another is the bamboo material price is not expensive, people can easily buy a good quality of bamboo flute. But in recent years, with the deepening of the reform of colleges and universities, the Ministry of Education has put forward higher requirements for teachers. Teachers should not only have professional playing skills, but also constantly innovate their own teaching methods in the teaching process. This paper analyzes the actual situation of bamboo flute teaching in colleges and universities in China, and puts forward the corresponding teaching reform strategies of bamboo flute in colleges and universities.展开更多
In the process of college education, music curriculum is extremely important to a professional course, music professional students, must learn the corresponding courses in China. Bamboo is a kind of widespread playing...In the process of college education, music curriculum is extremely important to a professional course, music professional students, must learn the corresponding courses in China. Bamboo is a kind of widespread playing Musical Instruments, in the process of teaching, teachers should build and creative class, over the years with the deepening of education reform, the teachers have a certain understanding of education environment. Therefore, teachers must break the limitations brought by traditional education methods when necessary. Micro-class is a new carrier, which can play a key role in the innovation of bamboo flute teaching. Based on this, this paper mainly discusses the use strategy of micro lesson in bamboo flute music teaching in colleges and universities for reference by staff.展开更多
I have a wonderful family.We all like music very much.My mother is a music teacher.She is good at playing the piano and the violin.She also likes singing and she can sing many songs.My father is a doctor.He likes musi...I have a wonderful family.We all like music very much.My mother is a music teacher.She is good at playing the piano and the violin.She also likes singing and she can sing many songs.My father is a doctor.He likes music,too.After he comes back from work,he often listens to music.In fact,playing the flute and the erhu are his favorites.I enjoy playing the guitar though it's difficult to play.I practice playing it every day,so I can play it very well.I once won the second prize at a guitar concert in the city.But my sister thinks playing theguitar is boring.展开更多
The turbulence kinetic energy and heat transfer performance of air in spirally fluted tube were numerically studied at a constant wall temperature with Reynolds number(Re)between 5000 and 45000.Furthermore,the flow dy...The turbulence kinetic energy and heat transfer performance of air in spirally fluted tube were numerically studied at a constant wall temperature with Reynolds number(Re)between 5000 and 45000.Furthermore,the flow dynamics and heat transfer performance of spirally fluted tubes with five different geometric parameters as well as the effects of separation vortex and swirling wake flow on heat transfer and flow resistance were analyzed.According to the results,heat transfer is enhanced mainly because the fluid hit the windward side of the flute,thus generating a strong turbulence kinetic energy to further reconstruct the boundary layer.The second reason is that the formation of the recirculation zone between the flutes disturbs the boundary layer caused by the flow separation.With the increase of flute depth ratio(L_(d)/D),the separation vortex will become stronger and larger on the leeward side of flute.The separation vortex will break the boundary layer and improve the heat transfer capacity which is accompanied with the increase of fluid resistance.As the flute pitch length ratio(L_(p)/D)decreases,the spiral flow is strengthened,and meanwhile more wake flow is generated.The spiral flow causes little impact on enhancing heat transfer but inhibits the development of the separation vortex and fluid pulsation;in addition,the fluid resistance is reduced at the same time.The maximum value of the average Nusselt number appears when Re=5000,L_(d)/D=0.25 and L_(p)/D=1.00,which is 2.53 times the value of smooth tube.In view of the whole range of Reynolds number,the thermal performance enhancement factor indicates that L_(d)/D=0.15 and L_(p)/D=1.00 are the optimal geometric design parameters.展开更多
基金supported by the National Natural Science Foundation of China (No. 51475460)
文摘To improve the cutting performance of an hourglass worm gear hob and the accuracy of the resulting worm gear,the rake angles of the teeth on the pitch circle should be reduced.A method of forming the spiral flutes by using a variable transmission ratio was developed.This method ensures that the rake angles on the indexing torus of each tooth are approximately 0°.Based on the gear meshing theory and the hourglass worm forming method,the discretization mathematical model of the rake face of a planar double enveloping worm gear hob was established by using cylindrical generating surface,and the feed parameters for machining the rake face for a variable transmission ratio were obtained.The spiral flute was simulated and the hob was machined on a four axis CNC milling machine.A contourgraph was used to measure the rake angle.The measurement results showed that the proposed method can reduce the absolute value of the rake angle on both sides of the cutting teeth,which can be used for machining the spiral flute rake face of an hourglass worm gear hob.
基金supported by the project of National Natural Science Foundation of China (NSFC, Grant No. 12032006)。
文摘Spin effect of the small diameter shaped charge results in the centrifugal stress during the jet stretching process. Consequently, the jet scatters, which deceases the jet penetration capability. In the present study, a multi-section method was proposed to design the spin-compensation liner. The spincompensation rate(SCR) of the liner was defined as the specific angular velocity that a fluted liner can offset. Based on the plain stress theory, SPH numerical method was applied to study the converging process of the 2D fluted structure. The spin-compensation mechanism of the fluted structure was illustrated. Then, nine cross sections were chosen along the liner axis equidistantly. On each of the section, a 2D fluted structure was designed to offset a given initial angular velocity. After, the optimized fluted structures were integrated into a 3D fluted liner. Jet appearances of the normal liner and the fluted liners under different initial angular velocities were compared, which verifies the practicality of the multi-sectional method. The multi-section optimization method provides a new efficient method of designing the shaped charge liner for a specific usage.
文摘Arthur Miller's Death of a Salesman takes advantage of the flute music to strengthen the atmosphere of stage, thus acoustically making people immerse the scene of the drama. The paper explores the conflicts and connections in this drama through the flute music, such as work and family, agriculture and business, work and family.
文摘Fluted pumpkin(FP;Telfairia occidentalis)is an edible vegetable,grown in West Africa,that is used in traditional medicine for its regulatory effects on the male gonads.Scientific articles concerning the effects of FP were identified by searching PubMed,PubChem,Scopus,Springer,ResearchGate,Google Scholar and Web of Science;this literature was to better understand the effects of FP seed(FPS)and leaf(FPL)extracts on the testes.Data showed that in experimental animals extracts of FPL and FPS at 1/100 of the lethal dose promoted testis regeneration and improved testosterone concentration and sperm quality,while at higher doses they had antifertility effects.Several extracts of FPS and FPL,including ethanol,aqueous,methanol and hydroethanolic,had protective effects on the testes of study animals at lower doses(>50 mg/kg body weight),but at higher doses(>200 mg/kg body weight)they inhibited hormone synthesis,sperm quality and histomorphological structure,under both normal and disease conditions.The posttreatment effects of FPS on the gonads were reversible in young mature rats and FPS had slight systemic toxic effects.Although,there are inconsistencies in some of the published results,the current evidence suggests that FPS and FPL have both profertility and reversible antifertility effects in experimental animals.
文摘The manafacturing theory proposed in this paper is composed of the se-lection of the machining type(motions and adjustments)and the determination of thefunctions of motion parameters.The paper shows that the special revolving tools withconstant spiral angled egdes can be ground in the[x y (?)]or[x y z (?)]systembased on the conjugate theory and differential geometry.The functions of motion pa-rameters in these two systems are deduced.
基金This project is supported by National Natural Science Foundation of China (No.50675065).
文摘Based on the principles of differential geometry and kinematics, a mathematical model is developed to describe the grinding wheel axial cross-section with the radial cross-section of the flute in a given drill under the basic engagement condition between the generating flute and the generated grinding wheel （or disk milling tool）. The mathematical model is good for the flute in the radial cross-section consisting of three arcs. Furthermore, a CAD system is also developed to represent the axial cross-section of the grinding wheel （or disk milling tool）. With the system, the grinding wheel （or disk milling tool） axial cross-section that corresponds to the three-arc flute cross section can be conveniently simulated. Through the grinding experiment of drill flutes, the method and the CAD system are proved to be feasible and reasonable.
文摘Twist drill flute profile design is necessary in order to determine the required grinding wheel profile for a flute production. An accurate drill flute profile design is generated for two-flute conical twist drills using analytical equations to generate a drill flute profile design needed for the production of twist drills with straight lips. The required grinding wheel profile for a flute production was expressed in digitized form as well as in terms of two curve-fitted circular arcs. The drill flute profile geometry can never be precisely generated when required grinding wheel profile is represented by two circular arcs and the generated flute profile is just a very good approximation of the design flute profile. A CAD （computer aided design） software has been developed using MATLAB to determine the required grinding wheel profile for generating a given drill flute profile design.
文摘The flute is a kind of typical foreign musical instruments, as members of the group of typical modern instruments, flute sound very feminine, emotion is extremely rich, it is very convenient to carry and also more nimble, easy to learn all these advantages make flute study inspire more young people interested in, but unfortunately is currently in the process of flute teaching in colleges and universities in our country, Teaching scale is not big enough, said the creation of works of art is not prominent, and that's a big gap between western countries and China in the field of teaching still need to continuously reform and exploration of teaching method innovation to the flute teaching and combining the national music, can let the flute in the growing of China's historical and cultural soil, was developed. Based on this, this paper mainly discusses the reform and innovation strategies of university site teaching. For reference by relevant staff.
文摘Because of its special timbre, the flute is the preference of the ancient people in the court, even there are a lot of the imperial court musicians use the flute to perform, the flute is an important and indispensable good instrument in our country, its heritage also brought to the attention of the people, teaching investigation of flute, flute skill teaching have been mature enough at present. However, there are still some deficiencies in the cultivation of students' aesthetics, especially in the lack of subjective aesthetic action. Based on this, this paper mainly discusses the cultivation strategy of flute teaching aesthetic ability in colleges and universities. For reference by relevant staff.
文摘Bamboo flute has a deep history in our country, is the inheritance of Chinese national culture, players can use bamboo flute playing a variety of types of repertoire, and production of bamboo flute itself were lighter, very convenient to carry, another is the bamboo material price is not expensive, people can easily buy a good quality of bamboo flute. But in recent years, with the deepening of the reform of colleges and universities, the Ministry of Education has put forward higher requirements for teachers. Teachers should not only have professional playing skills, but also constantly innovate their own teaching methods in the teaching process. This paper analyzes the actual situation of bamboo flute teaching in colleges and universities in China, and puts forward the corresponding teaching reform strategies of bamboo flute in colleges and universities.
文摘In the process of college education, music curriculum is extremely important to a professional course, music professional students, must learn the corresponding courses in China. Bamboo is a kind of widespread playing Musical Instruments, in the process of teaching, teachers should build and creative class, over the years with the deepening of education reform, the teachers have a certain understanding of education environment. Therefore, teachers must break the limitations brought by traditional education methods when necessary. Micro-class is a new carrier, which can play a key role in the innovation of bamboo flute teaching. Based on this, this paper mainly discusses the use strategy of micro lesson in bamboo flute music teaching in colleges and universities for reference by staff.
文摘I have a wonderful family.We all like music very much.My mother is a music teacher.She is good at playing the piano and the violin.She also likes singing and she can sing many songs.My father is a doctor.He likes music,too.After he comes back from work,he often listens to music.In fact,playing the flute and the erhu are his favorites.I enjoy playing the guitar though it's difficult to play.I practice playing it every day,so I can play it very well.I once won the second prize at a guitar concert in the city.But my sister thinks playing theguitar is boring.
基金This work was supported by the National Key Research and Development Program of China(Grant No.2018YFE0196000)IWHR Basic Scientific Research Projects(No.MK2018J09,No.MK2020J06).
文摘The turbulence kinetic energy and heat transfer performance of air in spirally fluted tube were numerically studied at a constant wall temperature with Reynolds number(Re)between 5000 and 45000.Furthermore,the flow dynamics and heat transfer performance of spirally fluted tubes with five different geometric parameters as well as the effects of separation vortex and swirling wake flow on heat transfer and flow resistance were analyzed.According to the results,heat transfer is enhanced mainly because the fluid hit the windward side of the flute,thus generating a strong turbulence kinetic energy to further reconstruct the boundary layer.The second reason is that the formation of the recirculation zone between the flutes disturbs the boundary layer caused by the flow separation.With the increase of flute depth ratio(L_(d)/D),the separation vortex will become stronger and larger on the leeward side of flute.The separation vortex will break the boundary layer and improve the heat transfer capacity which is accompanied with the increase of fluid resistance.As the flute pitch length ratio(L_(p)/D)decreases,the spiral flow is strengthened,and meanwhile more wake flow is generated.The spiral flow causes little impact on enhancing heat transfer but inhibits the development of the separation vortex and fluid pulsation;in addition,the fluid resistance is reduced at the same time.The maximum value of the average Nusselt number appears when Re=5000,L_(d)/D=0.25 and L_(p)/D=1.00,which is 2.53 times the value of smooth tube.In view of the whole range of Reynolds number,the thermal performance enhancement factor indicates that L_(d)/D=0.15 and L_(p)/D=1.00 are the optimal geometric design parameters.
