Applied Mechanics and Materials Vols. 55-57

Abstract: This paper applies high-pressure reactor to simulate conditions of thermal recovery and uses formic acid as hydrogen donor body, self-made oil-soluble organic nickel salt as catalyst and urea as auxiliary agents to conduct the study on of heavy oil. By TG-DTA, IR and NMR spectra, it makes an analysis on thermal transformation behavior and structural changes of asphaltine in heavy oil before and after the reaction of upgrading and viscosity reduction under the effect of auxiliary agents. The results show that the stability of the asphaltine in heavy oil after aquathermolysis reaction of hydrogen donor catalyzing is decreased. Infrared spectroscopy analysis reveals that the absorption peaks of IR functional groups of asphaltine in heavy oil is unchanged and the addition of auxiliary agents basically does not change the structure of asphaltine. NMR structural analysis shows that.

Abstract: Robust design is less sensitive to the manufacturing variation and its demand for controlling the manufacturing variation can be reduced. The existing robust design techniques are limited to solve individual synthesis problems, and these methods seldom consider the problem of tolerance sensitivity. This paper presents a method for tolerance sensitivity design and evaluation. First, tolerance sensitivity robustness is analyzed and the tolerance sensitivity robust design models are developed. Then, the matrix analysis method is introduced to evaluate complex assembly relationship among design functions and parameters. The results show that compared with origional mothod, the proposed method is siutble and reliable.

Abstract: Depended on the continuous development of nanotechnology, many micro-nano positioning platforms have been developed. Considering the actual engineer need, technologies for design of the positioning platform with both large travel and nano scale accuracy have become an important research direction. Several large travel driving systems with nano resolution are compared, and further key technologies of large travel and ultra precision for design are also discussed. Analysis result is that there are two kinds of types of micro-nano positioning platform at present, that’s flexible hinges arranged structure and integrative mechanism of both general driving system and flexible structure. Merits and shortcomings for these two kinds of micro-nano positioning platforms are all presented and some useful conclusions are brought forward.

Abstract: The stability and bifurcation behavior of Jeffcott rotor with local rubbing are investigated in terms of Hartman-Grobman theorem in this paper. The case with double zero real part of eigenvalues is analyzed by means of the theory of center manifold and n-dimension Hopf bifurcation. Along with discussion for the effects of parameters on system stability and bifurcation behavior, numerical simulation of rotor locus is conducted and the stability condition is derived.

Abstract: Jointly Managed Inventory(JMI) can balance upstream and downstream enterprises' risk-sharing authority and responsibility by the coordination of their common stock, suppliers and manufacturers, and can share their joint stock of raw materials, manufacturers and sale agents can share and sales their joint stock of finished product. Third-party stock mode is one of the typical implementation modes in JMI system. In the paper, we tried to discusses and analyse the key points in implementation strategies in JMI system of third-party logistics enterprise.

Abstract: Transient Statistic Energy Analysis (T. S. E. A.) for transient response of a vibration system is investigated in this paper. Mathematical expressions of the rise time and the peak energy were derived. Numerical modeling of the system was also made. It showed that the peak energy decrease as the internal loss factor and the coupling stiffness decrease, the rise time decease as the internal loss factor and the coupling loss factor increase. It was found that the results of TSEA and the traditional methods are identical.

Abstract: Identifying ground stress based on rock core discing can save a lot of surveying cost, so studying “rock core disicing” has great meaning. Aiming at the limitation of conventional methods, the particle swarm optimization (PSO) arithmetic is introduced to be combined with numerical simulation, so as to identify the ground stress based on rock core disicing observation. The objective function of optimization is constructed by combing Mohr-Coulomb criterion and tension criterion. Adopts dynamically adjusting momentum term method and steric compression method so as to improve the PSO in convergence velocity and globally searching property. The proposed method is mentioned and used to identify the ground stress of Bakken formation in USA. The arithmetic has good convergence speed and the identified results are coincident with the former reported results.

Abstract: First-principle calculations were performed for the study of the superconductor MgB₂ and AlB₂. The doping effect of compound Mg_1-xAl_xB₂ was analyzed by supercell method. Band structure, electronic bands structure, total and partial densities of states were calculated and analyzed in detail. Covalent bond effects (CBC) appeared in the electronic bands structure when doping Al to MgB₂. It is found that this CBC effects on Mg_1-xAl_xB₂ samples have prominent relations to superconductivity. The study of the density of state indicates that the superconductivity decreases with the increase of compound Al. In particular, there exists the transition of superconductor to non-superconductor with the change of x. The theoretical predictions agreed well with experimental measurements.

Abstract: Relational similarities between two pairs of words are the degrees of their semantic relations. Vector Space Model (VSM) is used to measure the relational similarity between two pairs of words, however it needs create patterns manually and these patterns are limited. Recently, Latent Relational Analysis (LRA) is proposed and achieves state-of-art results. However, it is time-consuming and cannot express implicit semantic relations. In this study, we propose a new approach to measure relational similarities between two pairs of words by combining Wordnet3.0 and the Web-Wikipedia, thus implicit semantic relations from the very large corpus can be mined. The proposed approach mainly possesses two characters: (1) A new method is proposed in the pattern extraction step, which considers various part-of-speeches of words. (2) Wordnet3.0 is applied to calculate the semantic relatedness between a pair of words so that the implicit semantic relation of the two words can be expressed. Experimental evaluation based on the 374 SAT multiple-choice word-analogy questions, the precision of the proposed approach is 43.9%, which is lower than that of LRA suggested by Turney in 2005, but the suggested approach mainly focuses on mining the semantic relations among words.

Abstract: The forming scheme of a side-plate of the core part in parallel flow evaporator was studied. Two forming schemes were compared and the explicit dynamic software DYNAFORM was applied to make simulations about the forming processes. According to comparisons between two forming schemes, the optimized scheme and process parameters were determined. Multi-station dies were designed based on the optimized process. Successful experiments with the dies showed that numerical simulation provided an efficient way for the optimization of the forming scheme in the side-plate production.