On the basis of the model experiments, a software for optimum design of the shearer drum has been developed, and the main parameters of a shearer drum also have been optimized. The combination of the techniques of opt...On the basis of the model experiments, a software for optimum design of the shearer drum has been developed, and the main parameters of a shearer drum also have been optimized. The combination of the techniques of optimization with the mod el experiment makes the designing and theoretical systems of the shearer drum more perfect.展开更多
Modem technology and manufacturing methods often require engineers who understand the fundamental principles of vibration theory and who are also skilled in vibration applications. Simply processing, remembering and a...Modem technology and manufacturing methods often require engineers who understand the fundamental principles of vibration theory and who are also skilled in vibration applications. Simply processing, remembering and applying the material learned from lectures and laboratory experiments With artificial criteria are inadequate. Hands-on teaching techniques with real-world problems are needed to complete the engineering students＇ education. This paper demonstrates how hands-on experiments performed in industry support and increase the students＇ understanding of fundamental principles and skill in their applications. Graduates with both knowledge and skill are more competitive in today＇s job market. A one-quarter industry-based vibration course was developed and taught with a hands-on segment at the Manufacturing and Mechanical Engineering and Technology （MMET） program at Oregon Institute of Technology （OIT） - Portland Campus. This novel instructional approach provided students with the opportunity to immediately apply material, learned in class and laboratory, in real-world industry situations with real-world problems. This instructional approach is applicable in many engineering fields and the author found the mechanical vibrations class particularly well suited for this instructional design style. The hands-on approach, grounded in the vibration course curriculum, provided a direct link to the fundamentals of vibration in industry. Student comments are included to demonstrate the value perceived by the students. Although this curriculum experiment involved mechanical engineering technology students, it would benefit mechanical engineering students equally well. In addition, the paper provides a brief description of the industries that participated in this project. Industries were selected because they use vibration based manufacturing, perform extreme testing or design their products to avoid failure due to vibrations.展开更多
The aim of this research was to find out whether the effect of chemical corrosion changes mechanical characteristics of surface layers of wooden construction elements. Degradation of the surface layers of wood was cau...The aim of this research was to find out whether the effect of chemical corrosion changes mechanical characteristics of surface layers of wooden construction elements. Degradation of the surface layers of wood was caused by chemical reactions of the basic substances of wood mass with compounds contained in antifire coatings. Fire retardants containing corrosive substances were often and repeatedly used in the Czech Republic on many wooden building constructions. This process of chemical corrosion is in practise called as ＂surface defibering of wood＂. This contribution presents standard and special experimental methods used for measuring the selected mechanical characteristics （compression strength, tension strength, bending strength, hardness and impact resistance） in the damaged surface layer of wooden construction elements. The material for experimental measuring was a construction element removed from a historical roof （ca 150 years old）. Mechanical characteristics of the surface layer of the defibered element were compared with the values measured in the deeper subsurface layer of non-damaged wood. The results of the experiments proved loss of cohesive strength and decrease of mechanical characteristics of wood only in a thin surface layer.展开更多
Effect of slope inclination on step friction coefficient of human being was studied by gait friction tester developed by Henan University of Science and Technology.It is beneficial to improving the safety of human bei...Effect of slope inclination on step friction coefficient of human being was studied by gait friction tester developed by Henan University of Science and Technology.It is beneficial to improving the safety of human beings while walking on a ramp.Based on the trajectory of mass center of body(MCOB)and the mechanical analysis of human body while walking,conclusion could be drawn that the required step frictional coefficient(RSFC)exhibited an"M"shaped curve during the foot contacting with the ground and got its maximum and minimum values when MCOB of the subject was at the highest and lowest position respectively.Moreover,the first peak of RSFC decreases firstly and then increases,while the second peak of RSFC increases with the increase of slope inclination at the experimental condition.The position of pivotal point is decided by the relative size of slope inclination and the angle between the plumb line through MCOB and the line from foot to MCOB.展开更多
文摘On the basis of the model experiments, a software for optimum design of the shearer drum has been developed, and the main parameters of a shearer drum also have been optimized. The combination of the techniques of optimization with the mod el experiment makes the designing and theoretical systems of the shearer drum more perfect.
文摘Modem technology and manufacturing methods often require engineers who understand the fundamental principles of vibration theory and who are also skilled in vibration applications. Simply processing, remembering and applying the material learned from lectures and laboratory experiments With artificial criteria are inadequate. Hands-on teaching techniques with real-world problems are needed to complete the engineering students＇ education. This paper demonstrates how hands-on experiments performed in industry support and increase the students＇ understanding of fundamental principles and skill in their applications. Graduates with both knowledge and skill are more competitive in today＇s job market. A one-quarter industry-based vibration course was developed and taught with a hands-on segment at the Manufacturing and Mechanical Engineering and Technology （MMET） program at Oregon Institute of Technology （OIT） - Portland Campus. This novel instructional approach provided students with the opportunity to immediately apply material, learned in class and laboratory, in real-world industry situations with real-world problems. This instructional approach is applicable in many engineering fields and the author found the mechanical vibrations class particularly well suited for this instructional design style. The hands-on approach, grounded in the vibration course curriculum, provided a direct link to the fundamentals of vibration in industry. Student comments are included to demonstrate the value perceived by the students. Although this curriculum experiment involved mechanical engineering technology students, it would benefit mechanical engineering students equally well. In addition, the paper provides a brief description of the industries that participated in this project. Industries were selected because they use vibration based manufacturing, perform extreme testing or design their products to avoid failure due to vibrations.
文摘The aim of this research was to find out whether the effect of chemical corrosion changes mechanical characteristics of surface layers of wooden construction elements. Degradation of the surface layers of wood was caused by chemical reactions of the basic substances of wood mass with compounds contained in antifire coatings. Fire retardants containing corrosive substances were often and repeatedly used in the Czech Republic on many wooden building constructions. This process of chemical corrosion is in practise called as ＂surface defibering of wood＂. This contribution presents standard and special experimental methods used for measuring the selected mechanical characteristics （compression strength, tension strength, bending strength, hardness and impact resistance） in the damaged surface layer of wooden construction elements. The material for experimental measuring was a construction element removed from a historical roof （ca 150 years old）. Mechanical characteristics of the surface layer of the defibered element were compared with the values measured in the deeper subsurface layer of non-damaged wood. The results of the experiments proved loss of cohesive strength and decrease of mechanical characteristics of wood only in a thin surface layer.
基金supported by the National Natural Science Foundation of China(Grant Nos.U1034002 and 51175149)
文摘Effect of slope inclination on step friction coefficient of human being was studied by gait friction tester developed by Henan University of Science and Technology.It is beneficial to improving the safety of human beings while walking on a ramp.Based on the trajectory of mass center of body(MCOB)and the mechanical analysis of human body while walking,conclusion could be drawn that the required step frictional coefficient(RSFC)exhibited an"M"shaped curve during the foot contacting with the ground and got its maximum and minimum values when MCOB of the subject was at the highest and lowest position respectively.Moreover,the first peak of RSFC decreases firstly and then increases,while the second peak of RSFC increases with the increase of slope inclination at the experimental condition.The position of pivotal point is decided by the relative size of slope inclination and the angle between the plumb line through MCOB and the line from foot to MCOB.
