Applied Mechanics and Materials Vols. 738-739

Abstract: Cracking of the cover concrete due to steel corrosion is considered as one of the major issues of durability of reinforced concrete (RC) structures. This paper tentatively studies the feasibility of DIC to reinforcement corrosion induced concrete fracture and cover cracking measurement. Advantages and limitations of DIC-based non-contact full-field measurement for corrosion induced concrete fracture and cover cracking are discussed. Drawbacks in this test need improvement are pointed out and test method for further study of whole process of simulating the real reinforced concrete cracking is put forward.

Abstract: Based on the basic principles of electromagnetism, the application of Shanghai Fudan-day Welcomes UNESCO Instruments Ltd. THQHC-1 type Helmholtz coil magnetic field measuring instrument for measuring coil uniform magnetic field generates a magnetic field on the carrier to get round the coil axis, online circle center at (coordinate origin) at the maximum magnetic field strength. Starting from the coordinate origin, to the sides, the magnetic field lines accelerate the decline, when the distance exceeds the coil radius, the decelerating decline. Conclusions for the understanding of a uniform magnetic field reference.

Abstract: The basic principle of neutron spectrum measured with time of flight method was simply introduced. The design of the experimental system for the time of flight spectrum detected in the thermal column of the reactor was offered. The most probable neutron energy of the measured thermal neutron was about 0.0248±0.0007eV, and the spectrum average energy was 0.042±0.001eV. The results showed that the measured spectrum was softer than thermal Maxwellian theory spectrum.

Abstract: White light interference technique for topography measurement effectively avoids phase ambiguity in phase-shifting interferometry. The spatial frequency domain algorithm based on scanning white light interference technique has the advantage of insensitivity to noise and higher calculation accuracy compared with other methods. The white light interference sensor is constructed based on nano positioning and nano measuring machine (NMM), the calibrated step height standard of 100±3nm is measured. The spatial frequency domain algorithm is adopted for data processing, the repetitive test result of 97.9nm and standard deviation of 0.48nm are achieved. To verify the measuring ability of complex device, the number ‘242’ on ink box is measured and three-dimensional reconstruction is conducted. The high precision and traceable measurements of micro/nano scale step height standard and complex devices are realized by the white light interference system based on NMM with steady frequency laser interferometer built-in.

Abstract: This paper proposes a new method of harmonic energy measurement based on atomic decomposition algorithm. Firstly, the matching pursuits (MP) algorithm is introduced and harmonic atom dictionary is designed according to the characteristics of signals to be analyzed to improve the effect of signal decomposition. Then, the MP algorithm is optimized by particle swarm optimization (PSO) to reduce the calculation amount. The simulation results of active harmonic energy in steady and unsteady state demonstrate feasibility and accuracy of the presented method.

Abstract: This paper presents the curve arc angle measurement control method of ship profiles CNC cold bending forming based on cubic parameter spline. The profile forming method, the approximate arc cubic parameter spline based on accumulative chord length and the principle of arc angle measurement control method are also given clearly. Experiments have been carried out to verify this method.

Abstract: There are the results of the acoustic emission (AE) signals spectrum modification during steel 30XGSA heating near the austenite transformation intervals. It is established in the AE signals spectrum during heating depend on steel phase structure. It makes possible the application of AE method for determination the austenite transformation borders. The critical points of austenite formations and austenite decay are based on heat treatment technologies. It is known, that there are phenomenon of steels properties modification without structure modification not for from phase transformation borders. This was very convenient for detecting the particles with foregone energy characteristics. The automated complex allows one to carry out measurements for a long time using two measuring setups in parallel, which is to study the dynamics of theological and acoustic features of the composition being studied.

Abstract: Considering the condition that many security accidents of school children have been occurred in campus which were mainly caused by the current lower effective management, this paper proposed a method of positioning the real-time locations of the school children by introducing the RFID technology. In this method, RFID readers were set up covering the campus (such as school gates, classrooms, corridors, playground) and it’s surrounding areas, and each school child was equipped with an ID card (It's actually a RFID tag). A system for dynamic monitoring and management of the school children was developed, which can detect the student cards in real-time and so as to monitor the locations of the school children, recognize dangerous areas and alert as well as automatic statistic of the school children’ attendance. So, it realized the automation and intelligence of the school children security management.

Abstract: In order to reduce operation risk and working intensity in mountainous orchard transportation and to realize optimized control for the mountainous orchard electric-drive monorail transportation system, a mountainous orchard electric-drive monorail transporter control system was designed and developed in this study. The system mainly consists of modules as: manual and remote control, positioning, obstacle avoidance, speed measurement, motor control, electric-magnetic break, and the position limit. The driving speed, current consumption, break control, and battery pack running ability experiments were conducted to test the control system. Results indicated that, the transporter’s driving speed is 0.60~0.58 m/s when it is running on the ground with the load weight from 0 to 100kg. This speed is little affected by the load weight. The transporter’s driving speed is 0.45~0.28 m/s when it is climbing a steep hill with an angle of 39°. That speed is critically affected by the load weight. In further improvements, a shift mechanism will be introduced so that adjustable gear ratio could be achieved thus solve the current overload problem in a full load situation.

Abstract: Typical wheeled or tracked robot could hardly apply to middle or small diameter underground pipelines laid by trenchless technology. Aiming at this kind of pipeline’s characteristics, this paper puts forward a basic structure of telescopic in-pipe robot. To provide necessary theoretical basis for the device selection, the mechanical model and force analyzing are given in detail. The speed of robot, as well as the motor torque of locking mechanism, could be expressed as the function of the robot’s structural parameters. As a result, the robot’s structural parameters take influence on its performance. In order to achieve the best performance, it is necessary to use the multi-objective optimization method to select these parameters. Using the genetic algorithm toolbox, the optimal solution of these parameters was obtained. Based on this, the motor torque of locking mechanism is minimum while the speed of the robot is maximum.