Applied Mechanics and Materials Vol. 459

Abstract: In this paper, a method to track marked points on the wings automatically to describe the wing kinematics in the coupled wing motion of flapping, pitching and rotating is introduced. The marked points on the surface of wings as tracking targets are determined, detected and matched by using digital image processing techniques. Three dimensions coordinates in marked points can be reconstructed by integrated 2D coordinates from multi-camera images and cameras calibration. By this method, it is shown in one flapping cycle, the trend of flapping angular speed various with time is approximate trapezoid function; the pitch angle changes rapidly; the rotation speed fast enhances 3.5 times as flapping frequency increase only 45%. It is possible aerodynamic effective can be improved remarkably.

Abstract: A voice coil motor (VCM) is the module to realize auto-focus function in mobile devices such as smartphones and tablet PCs. The VCM has very complicated structure in a small dimension. There are many faults like large hysteresis, short movement range and improper starting current. However, VCM makers are struggling to point out the cause of faults. Break-down analysis is also difficult to apply because main VCM parts are tightly bonded together and easily deformable during disassembly processes. Therefore, we proposed the novel diagnosis method of VCM faults without breaking it. Our method expected to classify the causes of faults by analyzing vibration characteristics of VCMs. Frequency spectrum characteristics and fast Fourier transform (FFT) spectrum analysis are performed. Experimental results revealed that natural frequency shifts shown for NG samples compare to good ones and the fluctuation of magnitude over natural frequency range appeared. Also, sidebands are observed in adjacent of integer multiple harmonic peaks for NG sample. We can find clear vibration characteristic differences caused by VCM defects. Therefore, the causes of defects expected to be classified and corresponding actions can be done in the production line that lead to high productivity of high quality VCM.

Abstract: In recent years, silica-gel-containing materials have formed components of biomaterials that can contact stem cells. However, the effects of silica gel particles on erythrogenesis have not been well-established. In this study, we evaluated the erythrogenic effects of silica gel particles on bone marrow cells and stromal cells pretreated with N-acetyl-L-cysteine (NAC) for 1 h prior to exposure to the silica gel particles. Our results showed that the numbers of erythrocytes in the bone marrow cells increased considerably following treatment with the silica gel particles. In addition, the expression of glycophorin A, an erythroid marker, was upregulated in the HEL-92 cells compared with the control cells. However, NAC pretreatment inhibited erythrogenic effects. Our study results suggest that silica gel particles might stimulate the differentiation of bone marrow cells to erythrocytes by increasing the generation of reactive oxygen species.

Abstract: Aim at the route deformation of rail state, a non-contact dynamic detection method based on trap-down inertial technology, was studied. Further study on integrated acceleration and real-time update of attitude matrix was made to put forward a proper solution. By experimental verification, this method is feasible and the error is within 5mm.

Abstract: This study uses Grey relational analysis (GRA) to evaluate a portion of the algebraic reasoning that uses multiple-representation of the life situation of multiple-representations. Current results of this study not only identify the easiest and hardest questions for students, but also show how proposed GRA provides a novel approach to educational testing.

Abstract: Drop Weight Tear Testing (DWTT) method is widely used for determining a materials ability to arrest a propagating crack. The influence factors of DWTT are discussed for X70 thick wall linepipe steel. The effects of nonuniformity of the material, ductile-brittle transition temperature, notch type, evaluation method of the fracture surface, machining method and the test equipments are discussed. Some solutions and recommendations to the problems are proposed.

Abstract: Fouling characteristic of plate heat exchanger was studied through the experimental system, with the Songhua River water as working fluid. Several water quality parameters: pH value, conductivity, dissolved oxygen, turbidity, hardness, alkalinity, chloride ion, iron ion, chemical oxygen demand, total bacterial count, which had great influence on the formation of fouling, as well as running condition, fouling resistance and other parameters were measured through the experimental system built. A group of fouling data of the typical water quality was obtained. Two prediction models of fouling characteristics of the plate heat exchanger were built based on partial least squares algorithm (PLS) and support vector regression machine (SVR) with water quality parameters as independent variables and fouling resistance as dependent variable, and the impact of water quality parameter on predicting accuracy was analyzed. Research results showed that: the prediction accuracy of two methods could be controlled within 12.5% and meet the requirements of the project. Through the comparison of the prediction results, it was proved that the SVR method was better than the method of PLS. The impact of the water quality parameters on prediction model was discussed by the means of deleting the water quality parameters one by one.

Abstract: A method to identify modal parameters from structural acoustical signals was proposed by a combination of empirical model decomposition (EMD) and stochastic subspace identification (SSI). Firstly, several intrinsic mode functions (IMF) were obtained with EMD, then the data obtained from the EMD was used as the input of the SSI to identify the modal parameters. Taking a wheel loader as an example, the acoustical signals in the loader cab were recorded through field tests, and were employed to identify the fundamental modal frequencies. The resultant frequencies show reasonable consistency with those by finite element analysis, and therefore prove the feasibility of the proposed method, which means that acoustical signals could be utilized as a useful supplement of the structural vibration responses in the modal parameter identification.

Abstract: This paper presented a method and technology about how to transmit geological disaster data. According to analyzing the NAT devices working principle, the TCP connection was created to stabilize the tuple mapping with the help of public network server, white can realize a P2P communication mechanism to transmit geological disaster data to remote PC directly. After analyzing the deficiencies about TCP protocol, some algorithms were added in application layer to improve TCP protocol in order to improve the communication mechanisms stability. By a great number of tests and practicalities, the mechanism can guarantee the geological disaster datas real-time and reliability which has some practical value to geological disaster monitoring.

Abstract: In this paper, we discuss one kind of Markov Skeleton processes, nonhomogeneous (H,Q) processes. We mainly study their distributions and moments of the first entrance time, and we obtain their recursive formula and some related properties.