Applied Mechanics and Materials Vols. 48-49

Abstract: The damage ‘freezing’ test of concrete was carried out with the static load and SHPB testing technique, so the relatively loss ultimate bearing capacity could express the damage in macro-level. The result showed that the dynamic damage of the concrete increased with the increasing strain or strain rate and the dynamic damage had a certain strain threshold. Based on the damage evolutive law of concrete whose probability density was distributed Weibul1 distribution, the impact damage factor equation was put forward. Besides, the unified equation which described the whole stress-strain process of the concrete after impact damage were established. Compared with the testing data, it showed that the experiment and theoretical results were in good agreement.

Abstract: RFID is an important part of Internet of things, however, solving tag anti-collision problem is the key to RFID. In order to improve the identification efficiency of anti-collision algorithm, the performance of the time slot ALOHA algorithm is analyzed and the improved ALOHA is proposed that when there is an unknown number of tags, the window size will be dynamically adjusted according to the anti-collision algorithm. When estimate the number of tags, the conflict probability is taken into account and according to the current window size, the return value of each read cycle, the calculated conflict probability, and the estimated number of tags, the window size will be dynamically adjusted. The number of tags and the colliding tags within one time slot can be identified quickly and the performance of the system and tag anti-collision algorithm will be improved. Through modeling and simulation, after comparing and analyzing the results, the practicability and feasibility of the improved anti-collision algorithm is verified.

Abstract: Human motion capture system based on a new kind of error compensation technology was developed and used this to assess human motion. On the basis of three-dimensional reconstruction and some essential factors influencing on the measurement accuracy, the measurement error theory and the modified and improved human motion analysis system was established. The experimental data indicate that the measurement precision of the modified and improved system is more precise than the original system on human motion measurement and capturing.

Abstract: Electrical resistance tomography (ERT) is always used in the field of detection of medicine、prospecting、two phase flow at the present time. It is rarely used to measure structure under condition of loading. In this paper, with the characters of different response - resistance effect showed by carbon fiber felt when attached to the different matrix, we developed a new type of smart layer of carbon fiber composites, the composite material has a very high pressure-resistance sensitivity, combined with ERT technology, the structure surface electrical resistivity distribute can be conversed, thus the structure of the surface of the load situation can be analyzed.

Abstract: This paper studies multi-vehicle and multi-cargo loading problem under the limited loading capacity. Hybrid heuristic algorithm is used to get the optimization solution. Firstly, adopt hybrid coding so as to make the problem more succinctly. On the basis of cubage-weight balance algorithm, construct initial solution to improve the feasibility. Adopt the improved non-uniform mutation so as to enhance local search ability of chromosomes. Secondly, stock elite by tabu searching algorithm to improve the searching efficiency of algorithm. Finally, the example can be shown that the algorithm is effective and can provide for large-scale ideas to solve practical problems.

Abstract: Considering the multiple and complicated driving conditions for tracked vehicles and their structural features, a comprehensive intelligent control method to deal with semi-active suspension was proposed based on the principle of magneto rheological damper. One half of the tracked vehicle suspension system is taken as the research object, where analysis is directed to the vertical amplitude, pitch angle and vertical body acceleration response. And the magneto rheological damper was taken as an actuator, the fuzzy control was taken as feedforward and PID control was taken as feedback. The control system model has been established by using of the complex random road output to simulink due to the condition of MATLAB/Simulink. The simulation results show that it is of good real-time control competence, good robustness and high accuracy, etc. Contrasting to passive suspension, some capability parameters such as the body vertical amplitude, pitch angle and the body vertical acceleration of the semi-active suspension system can had been well controlled by using of the intelligent hybrid control method, for exmple, the root mean square value of vertical amplitude decreased by 37.2%，the root mean square value of pitch angle decreased by 45.2% and root mean square value of the vertical vibration acceleration decreased by 38.6%.

Abstract: Taking tube bender system for producing pagoda-shaped fluorescent tubes as an example in this paper, four coordinates movement equations of CNC system with Parabolic characteristic are derived and an algorithm for nonlinear interpolation of four-axis linkage based on target point tracking algorithm is presented for the spiral fluorescent tube bending machine with CNC system by means of deep analysis of the pulse interval interpolation algorithm. By using this algorithm, coordinated control of four coordinates in tube bender system can be realized and, in addition, software programming procedure can be directly used for this system. Test shows that the system which uses this interpolation method has the characteristic of simple operation, high speed and high single-pulse interpolation accuracy.

Abstract: Solid powder boriding experiment was carried out on TC4 titanium alloy surface with method of RE(rare earth)-boriding at the temperature of over 1000°C. By means of XRD, SEM and EDS, phase composition, microstructure and morphology of TC4 titanium alloy after RE-boriding were investigated. The effect of rare earth on phase composition was discussed. Results of the experiment showed that the diffusion layer was composed of top-layer TiB2 and sub-layer TiB whiskers with the highest thickness being 25μm. The XRD results revealed TiB-TiB2 biphasic B-Ti compounds layer formed on the surface of TC4 after RE-boriding. The high content of B and Ce in the surface layer showed rare earth increased the absorption and concentration of B atoms.

Abstract: Detecting leakage liquid-filled pipe by acoustic emission instrument and researching the acoustic signal that measured with water by experimental medium. Gathering the acoustic signals in different pressures or different diameters of leakage aperture and analyzing the spectrum characteristics by wavelet packets and db5 wavelet basis. The result show that major frequency components contained at about 232KHz-239KHz. The acoustic emission signals’ amplitude and energy enhance as pressure and leakage aperture diameters’ increase.

Abstract: This study adopted a simulated evolutionary optimization algorithm, ant colony optimization algorithm to find the optimal unit commitment operation. The concepts such as status, strategy, and path, etc. were introduced to devise the optimization of unit commitment operation by ant colony optimization algorithm mode, so that the optimal unit commitment operation could be found by ant colony optimization algorithm. To cope with different constraints by additional penalties and restrict the statuses not satisfying the constraints by tabu table, the retrieval of ant colony optimization algorithm could always be performed in feasible region and the retrieval process of the algorithm was effectively conducted. It is feasible and efficient to find the optimal unit commitment operation by ant colony optimization algorithm, which was proved by stimulation.