Materials Science Forum Vols. 626-627

Abstract: A modeling method termed as the discrete time hybrid Diagnosis (DTHD) is presented to constructure models for a hydraulic punching machine. The DTHD method is an extension of the works on FDD (the fault detection and diagnosis) which are based on FSM-based modeling. FDD of DTHD models are suited for real time systems because of their capability of detecting faults leading to failures in terms of erroneous delays and deadlines. The occurrences of faults or failures are represented for individual system components by categorizing the set of states of each individual system component model into normal or failed conditions of various types. The condition corresponding to the states (of a component model) are represented by an unmeasurable variable. The components are then composed to produce the overall representation of failures on the whole system model with a single unmeasurable variable.

Abstract: Locally linear embedding (LLE) algorithm is an unsupervised technique recently proposed for nonlinear dimension reduction. In this paper,LLE manifold learning algorithm is introduced into the field of equipment fault diagnosis firstly, a method of the fault diagnosis based on LLE_KFDA is proposed. By LLE algorithm, original sample data is directly mapped to its’ intrinsical dimension space,which data still keep primary nonlinear form. then via kernel fisher discriminant analysis(KFDA), the characteristics data in intrinsical dimension space are mapped into knernel high-dimensional linear space,and then different fault data are discriminated based on a criterion of between-class and insid-class deviatione ratio maximum. LLE_KFDA algorithm is based on original data, avoided from fall of pattern recognition ability which caused by inappropriate or blind choice of the feature parameters in the traditional fault diagnosis method.The experiment to fault diagnosis of rolling bearing shows this method can effectively identify the equipment fault pattern, diagnostic result is good.

Abstract: A new fault diagnosis method to suppress cross terms of Wigner-Ville distribution (WVD) using Adaptive Short-time Fourier Transform (ASTFT) spectrum is put forward. The relationships of correlation between auto terms and cross terms of WVD are obtained theoretically by analyzing the WVD. Firstly, the signal ASTFT spectrum which can determine the signal component positions in the time-frequency plane is obtained. Then, the ASTFT spectrum as a window function is selected to process the signal WVD. Thus the cross terms can be effectively restrained. The simulation results show that a better resolution and more effective suppression of cross terms can be obtained. At last, the proposed method is applied to the fault diagnosis of bearing. The simulation and the experiment results indicate that the proposed method is effective in feature extraction.

Abstract: In order to meet the increasing requirements for express elevator control system and its intelligence and security, ARM chip is applied to construct hardware platform of elevator's main-board in this paper. BootLoader and the uCLinux are transplanted to this platform, and CAN-Bus and other related drivers are designed. A single elevator's operation algorithm is presented to achieve the elevator control logic. And the store and access of parameters of elevator are accomplished by real-time SQLite database. The main high-speed counting circuit is designed based on CPLD while the auxiliary one is based on AVR MCU, which guarantee the stability and reliability of the system. The operational results in elevator simulator verify the feasibility and efficiency of the control system.

Abstract: The key technologies about the 3D reconstruction of the bone SCT image for fast biological manufacture is discussed in this paper. Methods for 3D bone reconstruction are studied. Finally, an appropriate method based on bone SCT image is gained. SCT image is preprocessed, binary treated, and contour abstracted by SCT image abstraction system. This method can achieve following aims: processing outline data collection, reversing bone 3D surface and reconstructing 3D bionic model. The example in this work has shown how the 3D model of a bone is obtained through plane reconstructing successfully. Image processing algorithm is concluded, thereby providing necessary information for 3D reconstruction of bone SCT image.

Abstract: Three-dimensional (3D) highly porous poly (DL-lactic-co-glycolic acid)/tricalcium phosphate (PLGA/TCP) scaffolds were fabricated using a rapid prototyping technique (RP). The biopolymer carriers (4mm×4mm×4mm) subsequently were coated with collagen type I (Col) to produce PLGA/TCP/Col composites and utilized as an extracellular matrix for a cell-based strategy of bone tissue engineering. Autologous bone marrow stromal cells (BMSCs) harvested from New Zealand white rabbits were cultured under an osteogenic condition (BMSCs-OB) followed by seeding into the structural highly porous PLGA/TCP/Col composites (i.e. PLGA/TCP/Col/BMSCs-OB). Scanning electron microscopy observation found that the RP-based scaffolds had appropriate microstructure, controlled interconnectivity and high porosity. Modification of the scaffolds with collagen type I (PLGA/TCP/Col) essentially increased the affinity of the carriers to seeding cells, and PLGA/TCP/Col composites were well biocompatible with BMSCs-OB. The PLGA/TCP/Col/BMSCs-OB constructs were then subcutaneously implanted in the back of rabbits compared to controls with autologous BMSCs suspension and carriers alone. As a result, histological new bone formation was observed only in the experimental group with PLGA/TCP/Col/BMSCs-OB constructs 8 weeks after implantation. In the control group with scaffold alone only biodegradation of the carriers was found. Therefore, these results validate our bio-manufacturing methods for a new bone graft substitute.

Abstract: Advanced engineering techniques have been used in medical area wildly, but experience of surgeon is still relied heavily in dental implant in China. Aiming at this problem, a methodology of minimally invasive dental implant based on techniques of digital design and manufacturing is proposed, the procedure and some key problems of design and manufacturing are studied deeply. With designed implant plan based on 3D computer model reconstructed from CT images of oral and point cloud of oral plaster model, a surgical guide on the mucosa and teeth surface can be designed and fabricated. In clinical operation, the surgical guide is fixed on oral inner surface directly to guarantee the implant plan implemented accurately. Contrast to traditional dental implant, the minimally invasive surgery can be realized without soft tissue flap, and the temporary denture can be fabricated and fixed in the oral to recover the tooth function immediately. Clinical applications illustrate that, with proposed methodology, the efficiency and quality of implant operation can be improved effectively.

Abstract: With reference to the principle that the strong detonation wave generates the transient dynamic high pressure, the small power pulse power supply and the electrode micro-detonation wave generator are developed. The engineering ceramic material machining with low cost is realized successfully with the devices. It is shown from the study results that there is a degenerative layer about 0.25~0.45mm thick, which is composed of amorphous phases and crystalloid Si and can be machined and removed with the ceramic tool after micro-detonation machining. There are obvious transverse cracks near the interface of the degenerative layer and the matrix, but the cracks along the depth direction are not found. The performance of the degenerative layer is roundly analyzed and its removing mechanism is primitively discussed.

Abstract: On the basis of analyzing the shortcomings of the current technics for grooves machining, this paper deals with the development of Numerical Control System for machining of grooves in automobile synchronization regulator sleeve, which holds first-rate technics. In order to improve efficiency and precision of grooves machining and reduce cost of the cutter, Hypocycloid-based technique together with interpolation is introduced and studied. With IPC as system platform and PMAC (Programmable Multiple-Axes Controller) as the controlling center of the system, the open architecture of “PC-Based” is used in the CNC system and the framework of the CNC hardware is developed. According to the ideas of modularization and real-time multi-task scheduler, the CNC software system is carved into many modules and the framework of the CNC software is developed.

Abstract: Based on characteristic of stainless steel material, its milling performance is analyzed. Milling force of 1Cr18Ni9Ti stainless steel was obtained with single-factor test of milling depth, line spacing, and feed per tooth on a CNC Milling Machine. An empirical model for the milling force of stainless steel was established by regression. The validity of the model is verified by comparing the model data with the experimental data. The impact of milling parameters on milling force is sorted in order of milling depth, feed per tooth and line space according to the exponents in the model. The conclusions have great help for the milling cutting tool’s design of stainless steel and the selection of milling parameters .