Key Engineering Materials Vols. 474-476

Abstract: Taking the wheel-legged lunar rover based on double-half-revolution mechanism as a research object, this paper has made a dynamics simulation for the simplified virtual prototype model of lunar rover under several typical road conditions, with the purpose of obtaining the load applied on each bearing of lunar rover wheel-legged mechanism. On the basis of simulation analysis, static contact analysis for the wheel-leg rolling bearing was made by the finite element analysis software ANSYS. Through the finite element analysis for the rolling bearing, the maximum contact stress and deformation of the rolling body sustained the maximum force were obtained. The results will provide the new analytical method and basis for the optimization and lectotype design of the lunar rover wheel-leg rolling bearing.

Abstract: One of the key issues in ultrasonic tomography is the calculation of sensitivity and image reconstruction based on the sensitivity. A method is developed to calculate the sensitivity of ultrasonic tomography in rectangular area in this paper. On this basis, numerical modelling calculation of different substances distribution in a rectangular area is made of by using LBP algorithm, the standard Tikhonov regularization method and the Landweber iteration method respectively. Reconstruction simulation experiments of changing the quantity of pixel is conducted. The results show that imaging results of Tikhonov regularization method and the Landweber iterative method are consistent with the original image for the overdetermined problem and superior to those reconstructed by LBP algorithm. The image quality of Tikhonov in the underdetermined problems is poor than that in overdetemined problem and still better than that in the Landweber and LBP algorithm. Compared by numerical simulation, Tikhonov regularization method in both overdetermined or underdetermined problems are better than Landweber iteration and LBP algorithm, and LBP algorithm is only suitable to qualitative analysis.

Abstract: Key frame extraction is the precondition and fundamental of the video retrieval and video analysis. The method of key frame extraction determines the final result of video analysis. Firstly, the paper introduced the basic theories and principles of the Key frame extraction technology. Secondly, examined the typical method of key frame extraction techniques of video based on non-compression domain and compression-domain in detailed, at the same time, the evaluation and comparisons of the methods are made by experimental. Thirdly, the summarization is given and the prospection of Key frame extraction in the future is made in the end of paper.

Abstract: With the complexity of new products and devices increasing, the scheduling of semiconductor assembly and test producing line becomes more and more complicated. To deal with the problems of complex operation, low efficiency, high workload and unsatisfactory scheduling results in making plan, we develop a scheduling platform. This paper analyzes the features of the semiconductor assembly and test producing line, and builds the system from function design and database construction. At last, it presents the application of the system. Now the platform has successfully applied in a certain large semiconductor production enterprise. It helps schedulers make the scheduling more accurately and more conveniently; the scheduling results also can be supported for further decision-making clearly.

Abstract: Aims at the problem that the threshold number and value are difficulty to determine automatically existing in multi-threshold color image segmentation method, a novel method of multi-threshold segmentation in HSV is proposed. First of all, the image is pre-processed in HSV, component H and V is projected to S and be quantified at the same time. Secondly, histogram and advanced Histon histogram (AHH) are constructed. According to concept of roughness in the theory of Rough Set, the histogram of roughness (RSH) is constructed. Finally, according to requirement of segmentation accuracy, set a threshold Hn on RSH to determine the number and scope of multi-threshold and the image is segmented with above thresholds. The experimental results show that this method can determine the threshold quantity automatically, segment image efficiently and robust against illumination variation.

Abstract: For improving the travel time predication accuracy, a travel time predication model based multi-source historical is proposed. The model analyzes the different features between the loop detector data and the probing vehicles data, and creates traffic rules based on traffic patterns through data mining. Finally, the experiment of the navigation system based on multi-source historical data fusion is given. The results show the effectiveness of the model performs well.

Abstract: In this paper, a method of palmprint segmentation and location is proposed. The proposed method focuses on region of interest (ROI) extraction of palmprint images which involve transition and rotation. Firstly, binary of palmprint image is used to define the edge of palmprint. Then we separate the fingers and palms and find the two valley points of the index finger and middle finger, ring finger and little finger. Finally, rotate image based on the two valley points and correct image position and create coordinate system according to valley points to determine ROI. This method provides a necessary preprocessing for further feature extraction and matching.The effectiveness of the proposed method is verified using the PolyU palmprint database.

Abstract: The effect of operating conditions, such as adsorption time, adsorbent dosage, influent pH and influent oil concentration, on the performance of organic modified sepiolite used for the treatment of steel rolling oily wastewater was investigated via single factor method, and the adsorption kinetics and thermodynamics were also studied with batch test. Results indicated that oil removal rate reached 96.78% in 45 min which increased by 55.44% compared with crude sepiolite. Reasons for oil removal efficiency rise with organic modified sepiolite included augmentation of interlayer distance (0.007 nm larger than crude sepiolite), increase of specific surface area (from 41.63 to 104.40 m²/g) and stronger hydrophobic. The pseudo second order kinetic model well described experiment data with a perfect correlation coefficient value of 0.9999. Thermodynamic parameters including the Gibbs free energy (△G⁰), enthalpy (△H⁰), and entropy (△S⁰) revealed that adsorption process was a spontaneous, exothermic and physical adsorption process.

Abstract: The composites of expanded graphite with TiO₂ (EG/TiO₂) were prepared in the method of impregnation, the morphology and crystal structure were characterized by the means of scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The decolorization performance of the EG/TiO₂ composites for the methyl orange aqueous solution were studied. The experimental results were shown as follows: the EG/TiO₂ composites maintained the porous and lamellar structure of EG, and a lot of anatase TiO₂ particles as a small lump distributed on surfaces and in layers of EG. The composites may contain the graphite both oxidized and un-oxidized, and there was no other organic group left in the composites, except for the functional groups of graphite. Moreover, the EG/TiO₂ composites had excellent decolorization performance for the methyl orange aqueous solution. When reacted for 90 min, the decolorization rate of the methyl orange aqueous solution was at the peak, up to 96.1%. We supposed that it was mainly due to the interaction between the strong adsorptive ability of EG and the degradation property of TiO₂ particles.

Abstract: Aiming at the sink problem of wheel-legged lunar rover with double-half-revolution mechanism when walking on the soft lunar surface, a foot mechanism is added at each end of the striding rods of the wheel-legs, in order to improve the contact property between wheel-leg foot and lunar soil. The foot mechanism is composed of a hemispherical lobed foot with friction holes and a rotational joint, and the lobed foot is connected with the striding rod through the rotational joint. Taking the mechanics properties of lunar soil into account, absorbing the present vehicle’s ground mechanics theory and related ground soil models, this paper established the stress distribution model of their interaction between wheel-leg foot and lunar soil, and then simplified the stress distribution model reasonably. By setting the parameters of foot mechanism and the properties of lunar soil, the stress distribution model was simulated and the relation curves about the driving force, subsidence amount, driving torque and load of the wheel-leg were obtained.