The asteroid is of great significance for studying the formation of planets, the origin of life on the Earth, the defense against the collision of asteroids to the Earth and the mining on asteroids. Due to the insufficient capacity of the existing propulsion technology, the velocity increment needed to optimize the asteroid capture is the key for a successful capture mission. This paper reviews the capture orbit optimization method for asteroid and the extended capture period with the impulse thrust and lowthrust propulsions, including the strategy to capture asteroids by the gravity assisted and resonant orbital techniques, the continuous low thrust and temporary asteroid capture, and the scheme of extending the capture period.
The vibration isolation system with cubic stiffness and Bouc-Wen type hysteresis shows complex nonlinear dynamic characteristics. An undamped response model is established based on an anhysteretic restoring force. An approximate analytical solution is derived by the harmonic balance method (HBM) and the Taylor expansion. An analytical/numerical method is proposed to calculate the damped response of the vibration isolation system, based on the HBM and Levenberg-Marquardt algorithm. For the multi-value non-smooth function terms, the harmonic term coefficients are obtained by applying the fast Fourier Transform for the calculated time-domain response. The proposed methods are applied to a nonlinear vibration isolation system with horizontal wire ropes. It is verified that the vibration isolation system has a softening-hardening stiffness with cubic stiffness and Bouc-Wen type hysteresis. Both hysteretic damping and linear damping can effectively suppress the resonance, while with the hysteretic damping, better vibration isolation performance is shown at high frequencies.
This paper analyzes the textbooks of mechanics, especially the textbooks and their teaching systems of theoretical mechanics and materials mechanics, including the national states of the mechanics courses, the textbooks, the achievements and problems of the teaching systems for elementary mechanics, the introduction of overseas elementary mechanics textbooks, focusing on the theoretical mechanics teaching and the teaching system in foreign countries.
The paper introduces the basic situation, characteristics and problems of the 7th teaching competition of youth faculty of Fundamental Mechanics Courses, which was held by the teaching guidance committee of foundation mechanics courses in colleges and universities of the Ministry of Education. Some suggestions were given to improve in teaching abilities of teachers. Through this paper, the teachers in colleges and universities in China can know this teaching competition and the problems reflected in the competition. This paper is also a reference for improving the teaching level and quality of fundamental mechanics courses in China.
Student-centered teaching and learning is now widely accepted in the modern higher education worldwide with active learning as its core. It is a big challenge for both the teachers and the students to turn successfully from the traditional teacher-centered teaching to the relatively new student-centered learning. This paper presents a discussion on the feasible and efficient ways from the traditional“teacher-centered teaching”to the “student-centered learning” organized by the Quality Assurance Office and the Center for Excellent Teaching of the Tongji University. Being used to the cramming teaching, some students lack the initiative of active learning, teachers should do their best to arouse students in class. Effective ways to encourage active learning include designing an appropriate quality evaluation system, focusing on student learning efficiency and ability improvement, with an effective teaching pedagogy such as the “peer instruction”, and the introductions of problems or projects without preset answers in class.
The Noether’s theorem is one of footstones in modern physics and mechanics, due to the correlations it has established between the conservation laws and the symmetries. The origin, the content and the related anecdotes of the Noether’s theorem are reviewed, as well as the relations between the J-integral, the Eshelby tensor and the Noether’s theorem.
Leonardo da Vinci, known as painter, sculptor, astronomer, inventor, musician, mathematician,anatomist, physiologist, geologist, botanist, writer, military engineer, architect and cartographer, is a representative figure of the Italian Renaissance humanism. This paper describes another aspect of Da Vinci：his research results of fluid mechanics and the contributions related with turbulence, flight, wave and storm, and it is concluded that he is the pioneer and founder of fluid mechanics science as well.