Method of change management based on dynamic machining error propagation

In multistage machining processes(MMPs),the final quality of a part is influenced by a series of machining processes,which are complex correlations.So it is necessary to research the rule of machin-ing error propagation to ensure the machining quality.For this issue,a change management method of quality control nodes(i.e.,QC-nodes) for machining error propagation is proposed.A new framework of QC-nodes is proposed including association analysis of quality attributes,quality closed-loop control,error tracing...     

Optimizing solution of fault location using single terminal quantities

This paper firstly evaluated the impedance method and traveling waves method for fault location, and studied the robustness of fault location method based on impedance. Then it proposed an assembled fault location method for a transmission line based on single-terminal electrical quantities, in which the fault zone was firstly determined by impedance method with robustness then the accurate fault position was pinpointed by traveling waves method. EMTP (Electromagnetic Transient Program) simulations showed that the proposed method can overcome the drawbacks of impedance method and traveling waves method when either one is used alone, and improve both the accuracy and the reliability of fault location. Supported by the National Natural Science Foundation of China (Grant Nos. 50077011 and 50377019) and the National Basic Research Program of China (“973” Project) (Grant No. 2004CB217906)     

Ultralight X-type lattice sandwich structure (II): Micromechanics modeling and finite element analysis

The methods of homogenization and finite elements are employed to predict the effective elastic constants and stress-strain responses of a new type of lattice structure, the X-structure proposed by the authors in a companion paper. It is shown that in most cases the predictions by the equivalent homogenization theory agree well with the experimental and 3-dimensional finite element calculated results. The theoretical and numerical study supports the argument that the X-structure is superior to the pyramid lattice structure in terms of mechanical strength. Supported by the National Basic Research Program of China (“973” Project) (Grant No. 2006CB601202), the National Natural Science Foundation of China (Grant Nos. 10632060, 10825210), the National “111” Project of China (Grant No. B06024) and the National High-Tech Research and Development Program of China (“863” Project) (Grant No. 2006AA03Z519)     

An e-quality control model for multistage machining processes of workpieces

To track and control the changes of process quality attributes in multistage machining processes (MMPs), an e-quality control (e-QC) model is proposed. The e-QC model is defined as a quality information service node with e-formalizing technology, whose input/output and intermediate process (that is IPO) are known to other nodes, and its implemention in MMPs is provided. In order to establish the e-QC model, a measuring network is constructed to acquire the original quality data, and the changes of process quality attributes are monitored and diagnosed by the integrated quality analysis tools attached to the e-QC, which can be tracked by information template network in real time. Furthermore, a hierarchical control method is adopted to coordinate e-QCs, in which the quality loss and adjusting cost are used to quantify the opportunities for e-QCs to improve process quality. At last, a prototype is developed to verify the proposed methods. Supported by the National Basic Research Program of China (“973”) (Grant No. 2005CB724106) and the National High-Tech Research and Development Program of China (“863”) (Grant No. 2007AA00Z108)     

Development of ecohydrological assessment tool and its application

The development of Hydro-Informatic Modelling System (HIMS) provides an integrated platform for hydrological simulation. To extend the application of HIMS, an ecohydrological modeling system named ecohydrological assessment tool (EcoHAT) has been developed. Integrating parameter-management tools, RS (remote sensing) inversion tools, module-design tools and GIS analysis tools, the EcoHAT provides an integrated tool to simulate ecohydrological processes on regional scale, which develops a new method on sustainable use of water. EcoHAT has been applied to several case studies, such as, the Yellow River Basin, the acid deposition area in Guizhou province and the riparian catchment of Guanting reservoir in Beijing. Results prove that EcoHAT can efficiently simulate and analysis the ecohydrological processes on regional scale and provide technical support to integrated water resources management on basin scale. Supported by the National Key Technology R&D Program in the 11th Five-year Plan of China (Grant No. 2006BAB06B07), the National Natural Science Foundation of China (Grant No. 40671123), the National Basic Research Program of China (“973” Project) (Grant Nos. 2005CB422207, G19990436), and the National Hi-Tech Research and Development Program of China (“863” Project) (Grant No. 2006AA12Z145)     

The solidification of two-phase heterogeneous materials: Theory versus experiment

The solidification behavior of two-phase heterogeneous materials such as close-celled aluminum foams was analytically studied. The proposed analytical model can precisely predict the location of solidification front as well as the full solidification time for a two-phase heterogeneous material composed of aluminum melt and non-conducting air pores. Experiments using distilled water simulating the aluminum melt to be solidified (frozen) were subsequently conducted to validate the analytical model for two selected porosities (ɛ), ɛ=0 and 0.5. Full numerical simulations with the method of finite difference were also performed to examine the influence of pore shape on solidification. The remarkable agreement between theory and experiment suggests that the delay of solidification in the two-phase heterogeneous material is mainly caused by the reduction of bulk thermal conductivity due to the presence of pores, as this is the sole mechanism accounted for by the analytical model for solidification in a porous medium. Supported by the National Basic Research Program of China (“973” Project) (Grant Nos. 2006CB601202, 2006CB601203), the National Natural Science Foundation of China (Grant Nos. 10572111, 10632060), the National 111 Project of China (Grant No. B06024) and the National High-Tech Research and Development Program of China (“863” Project) (Grant No. 2006AA03Z519).     

Optimization model and algorithm for mixed traffic of urban road network with flow interference

In this paper, the problem of interferences between motors and non-motors in urban road mixed traffic network is considered and the corresponding link impedance function is presented based on travel demand. On the base of this, the main factors that influence travelers’ traffic choices are all considered and a combined model including flow-split and assignment problem is proposed. Then a bi-level model with its algorithm for system optimization of urban road mixed traffic network is proposed. Finally the application of the model and its algorithm is illustrated with a numerical example. Supported by the National Natural Science Foundation of China (Grant No. 70631001) and the National Basic Research Program of China (“973”) (Grant No. 2006CB705500)     

Ductility of metal thin films in flexible electronics

Flexible, large area electronics using various organic and inorganic materials are beginning to show great promise. During manufacture and service, large deformation of these hybrid materials will pose significant challenges in terms of high performance and reliability. A deep understanding of the ductility or flexibility of macroelectronics becomes one of the major issues that must be addressed urgently. This paper describes the current level of understanding on the thin-film ductility, both free-standing and substrate-supported, and relevant influencing factors. Supported by the National Basic Research Program of China (Grant No. 2004CB619303), the 111 Project of China (Grant No. B06025), and the Science and Technology Key Project from Ministry of Education of China (Grant Nos. 02182, 03182)     

Design of a control system for a macro-micro dual-drive high acceleration high precision positioning stage for IC packaging

A macro-micro dual-drive positioning system showing good potential for high acceleration and high precision positioning required in IC packaging applications is devised in this paper. The dual-drive positioning stage uses a VCM (voice coil motor) driven macro positioning stage and a PZT piezo-electric driven micro positioning stage. The coupling characteristics of the system are analyzed to produce a control structure with a micro positioning stage that can dynamically compensate for the positioning error produced by the macro positioning stage. Models of the two positioning stages are described. The models cover both the mechanism and the actuator. For the macro positioning stage, friction characteristics are taken into account, and a controller with an LQG (linear-quadratic-Gaussian) control algorithm combining a feed-forward compensation algorithm is derived. A PID controller is used to control the micro positioning stage. Detailed designs are derived for the proposed approach, and the performance is validated by simulation. Supported by the National Natural Science Foundation of China (Grant No. 50705027), the National High Technology Research and Development Program of China (“863” Program) (Grant No. 2007AA04Z315) and Self-Planned Task of State Key Laboratory of Robotics and System (HIT) (Grant No. SKLRS200804B)     

Greenhouse gas emissions and reduction potential of primary aluminum production in China

A cradle-to-gate life cycle assessment was conducted in this paper to calculate the greenhouse gas (GHG) emissions, such as CO₂, CH₄, CF₄ and C₂F₆ emissions, based on statistic data of Chinese aluminum industry of the year 2003. The results showed that the GHG emissions for 1 t primary aluminum production was 21.6 t CO₂ equivalent which is 70% higher than that of worldwide average level of the year 2000. The main contributors of emission were the alumina refining and aluminum smelting process accounting for 72% and 22% in accumulative emission, respectively. According to the development and application of new process technologies for primary aluminum production and the ‘target of energy-saving and emissions-reducing’ of Chinese government, the reduction potential of the GHG emissions for alumina and aluminum production were estimated. The results indicated that China aluminum industry would achieve the target of reducing about 25% GHG emissions by the end of 2010. Supported by the National Natural Science Foundation of China (Grant No. 50525413), National Basic Research Program of China (973 Program) (Grant No. 2007CB613706), and Beijing Natural Science Foundation (Grant No. 2081001)     

Application of time reversal mirror technique in microwave-induced thermo-acoustic tomography system

Microwave-induced thermo-acoustic tomography (MITAT) is a promising technique with great potential in biomedical imaging. It has both the high contrast of the microwave imaging and the high resolution of the ultrasound imaging. In this paper, the proportional relationship between the absorbed microwave energy distribution and the induced ultrasound source distribution is derived. Further, the time reversal mirror (TRM) technique based on the pseudo-spectral time domain (PSTD) method is applied to MITAT system. The simulation results show that high contrast and resolution can be achieved by the TRM technique based on PSTD method even for the received signals with very low signal-to-noise ratio (SNR) and the model parameter with random fluctuation. Supported by the National Natural Science Foundation of China (Grant No. 60771042), the National Hi-Tech Research and Development Program (“863” Project) (Grant No. 2007AA12Z159), 111 Project (Grant No. B07046), SiChuan Excellent Youth Foundation (Grant No. 08ZQ026-039), Program for New Century Excellent Talents in University of China and Program for Changjiang Scholars     

Ultralight X-type lattice sandwich structure (I): Concept,fabrication and experimental characterization

A new type of ultra-lightweight metallic lattice structure (named as the X-type structure) is reported. This periodic structure was formed by two groups of staggered struts in the traditional pyramid structure, and fabricated by folding expanded metal sheet along rows of offset nodes and then brazing the folded structure (as the core) with top and bottom facesheets to form sandwich panels. The out-of-plane compressive and shear properties of the X-type lattice sandwich structure were investigated experimentally and compared to those of the sandwich having a pyramidal truss core. It is found that the formation of the 2-dimensional staggered nodes can effectively make the X-type structure more resistant to inelastic and plastic buckling under both compression and shear loading than the pyramidal lattice truss. Obtained results show that the compressive and shear peak strengths of the X-type lattice structure are about 30% higher than those of the pyramidal lattice truss having the same relative density. Supported by the National Basic Research Program of China (“973” Project) (Grant No. 2006CB601202), the National Natural Science Foundation of China (Grant Nos. 10632060,10825210), the National “111” Project of China (Grant No. B06024) and the National High-Tech Research and Development Program of China (“863” Project) (Grant No. 2006AA03Z519)     

Multi-channel micro neural probe fabricated with SOI

Silicon-on-insulator(SOI) substrate is widely used in micro-electro-mechanical systems(MEMS).With the buried oxide layer of SOI acting as an etching stop,silicon based micro neural probe can be fabri-cated with improved uniformity and manufacturability.A seven-record-site neural probe was formed by inductive-coupled plasma(ICP) dry etching of an SOI substrate.The thickness of the probe is 15 μm.The shaft of the probe has dimensions of 3 mm×100 μm×15 μm with typical area of the record site of 78.5 μm2.The im...     

Design and fabrication of erbium doped photosensitive fibers

A kind of erbium doped photosensitive fiber (EDPF) was proposed and fabricated, whose core was made of double layers named photosensitive layer and erbium doped layer. The double-layer core design can overcome difficulties in fabrication of EDPF with single core design, i.e. the conflict between the high consistency rare earth doping and high consistency germanium doping. A sample was fabricated through the modified chemical vapor deposition method combined with solution doping technique. The peak absorption coefficient was 48.80 dB/m at 1.53 μm, the background loss was lower than 0.1 dB/m, and the reflectivity of the fiber Brag gratings (FBG) written directly on the sample fiber was up to 97.3% by UV-writing technology. Moreover, a C band tunable fiber laser was fabricated using the sample fiber, in which a uniform FBG was written directly on EDPFs as a reflector. A single wavelength lasing with a maximum wavelength tuning range of 1555.2–1558.0 nm was achieved experimentally. Within this tuning range, the full-width at half maximum (FWHM) of the laser output was smaller than 0.015 nm and the side mode suppression ratio (SMSR) was better than 50 dB. Supported by the National High Technology Research and Development Program of China (863 Project) (Grant No. 2007AA01Z258), the National Natural Science Foundation of China (Grant No. 60771008), Program for New Century Excellent Talents in University (Grant No. NCET-06-0076), Beijing Natural Science Foundation (Grant No. 4052023), and the Beijing Jiaotong University Foundation (Grant No. 2006XM003)     

Classification of lying states for the humanoid robot SJTU-HR1

The humanoid robot SJTU-HR1’s concept is introduced and its characteristics tree is given. The basic states for SJTU-HR1 are proposed, including lying, sitting, standing and handstanding, abstracted from the daily exercises of human beings. The G _F (generalized function) set theory is exploited to achieve the kinematic characteristics of the interested EEs (end-effectors) of SJTU-HR1 for the lying states. Finally, the results show that the large amounts of states can be described using the abbreviations in a systematic manner. Although we have focused on the application of the G _F set theory to humanoid robots, particularly the SJTU-HR1, this methodology can also be applied to quadruped robots and hexapedal robots, especially when the desired tasks are complex. Supported by the Natural Basic Research Program of China (“973”) (Grant No. 2006CB705400), the National Natural Science Foundation of China (Grant Nos. 60534020, 30770538), Joint Research Fund for Young Scholars in China and Abroad (Grant No. 50728503), and the Graduate Innovation Foundation of Shanghai Jiao Tong University     

Deformation behavior of Cu-12wt%Al alloy wires with continuous columnar crystals in dieless drawing process

The microstructure and mechanical properties of Cu-12wt%Al alloy wires which are composed of continuous columnar crystals after dieless drawing forming at drawing speed of 1.0―1.4 mm/s and deformation temperature of 600―900℃ were analyzed, and deformation behavior of the alloy during dieless drawing forming was experimentally investigated. The results showed that in the abovemen-tioned conditions, recrystallization phenomenon was not found during dieless drawing forming. When a drawing speed of 1.0 mm/s was...     

A new method for nondestructive damage identification of lattice materials

This paper proposes vibration-based damage identification method, termed as substructure potential energy (SPE) method, which is capable of accurately estimating the damage magnitudes of multiple members. While other existing damage severity estimation methods require the information of several unabridged modes of the structure, the new method utilizes only a few lower mode shapes of substructures measured from the damaged solid. The performance of the proposed method is compared with one existing damage detection method, using a set of numerical simulations on a lattice material beam based on synthetic data generated from finite element models. Supported by the National Basic Research Program of China (“973”) (Grant No. 2006CB601206)     

An approach to error elimination for multi-axis CNC machining and robot manipulation

The geometrical accuracy of a machined feature on a workpiece during machining processes is mainly affected by the kinematic chain errors of multi-axis CNC machines and robots, locating precision of fixtures, and datum errors on the workpiece. It is necessary to find a way to minimize the feature errors on the workpiece. In this paper, the kinematic chain errors are transformed into the displacements of the workpiece. The relationship between the kinematic chain errors and the displacements of the position and orientation of the workpiece is developed. A mapping model between the displacements of workpieces and the datum errors, and adjustments of fixtures is established. The suitable sets of unit basis twists for each of the commonly encountered types of feature and the corresponding locating directions are analyzed, and an error elimination (EE) method of the machined feature is formulated. A case study is given to verify the EE method. Recommended by Prof. XIONG YouLun, Member of Editorial Committee of Science in China, Series E: Technological Sciences Supported by the National Natural Science Foundation of China (Grant Nos. 50475141, 50436010), the “973” Research Foundation of China (Grant No. 2005CB724103) and the Program for New Century Excellent Talents in University (Grant No. NCET-05-0651)     

Dynamic simulation and optimization approach to construction diversion of hydraulic and hydroelectric projects

To solve the engineering and scientific problems in construction diversion and its simulation analysis, a complete scheme is presented. Firstly, the complex constraint relationship was analyzed among main buildings, diversion buildings and flow control. Secondly, the time-space relationship model of construction diversion system and the general block diagram-oriented simulation model of diversion process were set up. Then, the corresponding numerical simulation method and 3D dynamic visual simulation method were put forward. Further, the simulation and optimization platform of construction diversion control process was developed, integrated with simulation modeling, computation and visualization. Finally, these methods were applied to a practical project successfully, showing that the modeling process is convenient, the computation and the visual analysis can be coupled effectively, and the results conform to practical state. They provide new theoretical principles and technical measures for analyzing the control problems encountered in construction diversion of hydraulic and hydroelectric engineering under complex conditions. Supported by the National Basic Research Program of China (“973” Program) (Grant No. 2007CB714101), the National Key Technology R&D Program in the 11th Five year Plan of China (Grant No. 2006BAB04A13) and the National Science Fund for Distinguished Young Scholars of China (Grant No. 50525927)     

Numerical modeling of concrete hydraulic fracturing with extended finite element method

The extended finite element method (XFEM) is a new numerical method for modeling discontinuity. Research about numerical modeling for concrete hydraulic fracturing by XFEM is explored. By building the virtual work principle of the fracture problem considering water pressure on the crack surface, the governing equations of XFEM for hydraulic fracture modeling are derived. Implementation of the XFEM for hydraulic fracturing is presented. Finally, the method is verified by two examples and the advan- tages of ...