Search results for: interface layer

Authors: Roslinda Nazar, Anuar Ishak, Ioan Pop

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Unsteady boundary layer flow of an incompressible micropolar fluid over a stretching sheet when the sheet is stretched in its own plane is studied in this paper. The stretching velocity is assumed to vary linearly with the distance along the sheet. Two equal and opposite forces are impulsively applied along the x-axis so that the sheet is stretched, keeping the origin fixed in a micropolar fluid. The transformed unsteady boundary layer equations are solved numerically using the Keller-box method for the whole transient from the initial state to final steady-state flow. Numerical results are obtained for the velocity and microrotation distributions as well as the skin friction coefficient for various values of the material parameter K. It is found that there is a smooth transition from the small-time solution to the large-time solution.

Keywords: Boundary layer, micropolar fluid, stretching surface, unsteady flow.

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Authors: Wei Jun-xia, Yuan Guang-wei, Yang Shu-lin, Shen Wei-dong

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In order to make conventional implicit algorithm to be applicable in large scale parallel computers , an interface prediction and correction of discontinuous finite element method is presented to solve time-dependent neutron transport equations under 2-D cylindrical geometry. Domain decomposition is adopted in the computational domain.The numerical experiments show that our parallel algorithm with explicit prediction and implicit correction has good precision, parallelism and simplicity. Especially, it can reach perfect speedup even on hundreds of processors for large-scale problems.

Keywords: Transport Equation, Discontinuous Finite Element, Domain Decomposition, Interface Prediction And Correction

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Authors: Ju Young Lee, Jung-Seok Yang, Jaeyoung Choi

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The purpose of this paper primarily intends to develop GIS interface for estimating sequences of stream-flows at ungauged stations based on known flows at gauged stations. The integrated GIS interface is composed of three major steps. The first, precipitation characteristics using statistical analysis is the procedure for making multiple linear regression equation to get the long term mean daily flow at ungauged stations. The independent variables in regression equation are mean daily flow and drainage area. Traditionally, mean flow data are generated by using Thissen polygon method. However, method for obtaining mean flow data can be selected by user such as Kriging, IDW (Inverse Distance Weighted), Spline methods as well as other traditional methods. At the second, flow duration curve (FDC) is computing at unguaged station by FDCs in gauged stations. Finally, the mean annual daily flow is computed by spatial interpolation algorithm. The third step is to obtain watershed/topographic characteristics. They are the most important factors which govern stream-flows. In summary, the simulated daily flow time series are compared with observed times series. The results using integrated GIS interface are closely similar and are well fitted each other. Also, the relationship between the topographic/watershed characteristics and stream flow time series is highly correlated.

Keywords: Integrated GIS interface, spatial interpolation algorithm, FDC.

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Authors: Juhan Kim, Soohyung Kim, Kiyoung Moon

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In this paper, we design an integration security system that provides authentication service, authorization service, and management service of security data and a unified interface for the management service. The interface is originated from XKMS protocol and is used to manage security data such as XACML policies, SAML assertions and other authentication security data including public keys. The system includes security services such as authentication, authorization and delegation of authentication by employing SAML and XACML based on security data such as authentication data, attributes information, assertions and polices managed with the interface in the system. It also has SAML producer that issues assertions related on the result of the authentication and the authorization services.

Keywords: XML, XML Security, XACML.

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Authors: Sang Hoon Lee, Tae Il Lee, Su Jeong Lee, Jae Min Myoung

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In order to manufacture short gap single Si nanowire (NW) field effect transistor (FET) by imprinting and transferring method, we introduce the method using Al2O3 sacrificial layer. The diameters of cylindrical Si NW addressed between Au electrodes by dielectrophoretic (DEP) alignment method are controlled to 106, 128, and 148 nm. After imprinting and transfer process, cylindrical Si NW is embedded in PVP adhesive and dielectric layer. By curing transferred cylindrical Si NW and Au electrodes on PVP-coated p++ Si substrate with 200nm-thick SiO2, 3μm gap Si NW FET fabrication was completed. As the diameter of embedded Si NW increases, the mobility of FET increases from 80.51 to 121.24 cm2/V·s and the threshold voltage moves from –7.17 to –2.44 V because the ratio of surface to volume gets reduced.

Keywords: Al2O3 Sacrificial transfer layer, cylindrical silicon nanowires, Dielectrophorestic alignment, Field effect transistor.

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Authors: Namal A. Senanayake, Khoo B. How, Quah W. Wai

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In this project, a tele-operated anthropomorphic robotic arm and hand is designed and built as a versatile robotic arm system. The robot has the ability to manipulate objects such as pick and place operations. It is also able to function by itself, in standalone mode. Firstly, the robotic arm is built in order to interface with a personal computer via a serial servo controller circuit board. The circuit board enables user to completely control the robotic arm and moreover, enables feedbacks from user. The control circuit board uses a powerful integrated microcontroller, a PIC (Programmable Interface Controller). The PIC is firstly programmed using BASIC (Beginner-s All-purpose Symbolic Instruction Code) and it is used as the 'brain' of the robot. In addition a user friendly Graphical User Interface (GUI) is developed as the serial servo interface software using Microsoft-s Visual Basic 6. The second part of the project is to use speech recognition control on the robotic arm. A speech recognition circuit board is constructed with onboard components such as PIC and other integrated circuits. It replaces the computers- Graphical User Interface. The robotic arm is able to receive instructions as spoken commands through a microphone and perform operations with respect to the commands such as picking and placing operations.

Keywords: Tele-operated Anthropomorphic Robotic Arm and Hand, Robot Motion System, Serial Servo Controller, Speech Recognition Controller.

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Authors: M. Maronek, J. Barta, P. Palcek, K. Ulrich

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Low carbon deep drawing steel DC 01 according to EN 10130-91 was nitrooxidized in dissociated ammonia at 580°C/45 min and consequently oxidised at 380°C/5 min in vapour of distilled water. Material after nitrooxidation had 54 % increase of yield point, 34 % increase of strength and 10-times increased resistance to atmospheric corrosion in comparison to the material before nitrooxidation. The microstructure of treated material consisted of thin ε-phase layer connected to layer containing precipitated massive needle shaped Fe4N - γ' nitrides. This layer passed to a diffusion layer consisting of fine irregular shaped Fe16N2 - α'' nitrides regularly dispersed in ferritic matrix. Fatigue properties were examined under bending load with frequency of 20 kHz and sinusoidal symmetric cycle. The results confirmed positive influence of nitrooxidation on fatigue properties as fatigue limit of treated material was double in comparison to untreated material.

Keywords: steel sheet, fatigue, nitrooxidation, S-N diagram

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Authors: Volodymyr Chegel

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The computer modeling is carried out for parameter of sensitivity of optoelectronic chemical and biosensors, using phenomena of surface plasmon resonance (SPR). The physical model of SPR-sensor-s is described with (or without) of modifications of sensitive gold film surface by a dielectric layer. The variants of increasing of sensitivity for SPR-biosensors, constructed on the principle gold – dielectric – biomolecular layer are considered. Two methods of mathematical treatment of SPR-curve are compared – traditional, with estimation of sensor-s response as shift of the SPRcurve minimum and proposed, for system with dielectric layer, using calculating of the derivative in the point of SPR-curve half-width.

Keywords: Surface Plasmon Resonance, modeling, sensitivity, biosensor

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Authors: Adekitan I. Aderibigbe, Fakolujo A. Olaosebikan

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The parameters of a two-layer soil can be determined by processing resistivity data obtained from resistivity measurements carried out on the soil of interest. The processing usually entails applying the resistivity data as inputs to an optimisation function. This paper proposes an algorithm which utilises the square error as an optimisation function. Resistivity data from previous works were applied to test the accuracy of the new algorithm developed and the result obtained conforms significantly to results from previous works.

 

Keywords: Algorithm, earthing, resistivity, two-layer soil-model.

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Authors: Vinay K. Nangia, Cashmira Pramanik

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Academia-industry relationship is not like that of technology donator-acceptor, but is of interactive and collaborative nature, acknowledging and ensuring mutual respect for each other-s role and contributions with an eye to attaining the true purpose of such relationships, namely, bringing about research-outcome synergy. Indeed, academia-industry interactions are a system that requires active and collaborative participations of all the stakeholders. This paper examines various issues associated with academic institutions and industry collaboration with special attention to the nature of resources and potentialities of stakeholders in the context of knowledge management. This paper also explores the barriers of academia-industry interaction. It identifies potential areas where industry-s participation with academia would be most effective for synergism. Lastly, this paper proposes an integrated model of several new collaborative approaches that are possible, mainly in the Indian scenario to strengthen academia-industry interface.

Keywords: academia-industry, interface, knowledge economy, technology transfer.

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Authors: W. J. Stępniowski, W. Florkiewicz, M. Norek, M. Michalska-Domańska, E. Kościuczyk, T. Czujko

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In this paper, two options of anodic alumina barrier layer thinning have been demonstrated. The approaches varied with the duration of the voltage step. It was found that too long step of the barrier layer thinning process leads to chemical etching of the nanopores on their top. At the bottoms pores are not fully opened what is disadvantageous for further applications in nanofabrication. On the other hand, while the duration of the voltage step is controlled by the current density (value of the current density cannot exceed 75% of the value recorded during previous voltage step) the pores are fully opened. However, pores at the bottom obtained with this procedure have smaller diameter, nevertheless this procedure provides electric contact between the bare aluminum (substrate) and electrolyte, what is suitable for template assisted electrodeposition, one of the most cost-efficient synthesis method in nanotechnology.

Keywords: Anodic aluminum oxide, anodization, barrier layer thinning, nanopores.

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Authors: Ebadollah Zohrevandi, Rasoul Roustaei, Omid Moradtalab

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In this paper, we first consider the quality of service problems in heterogeneous wireless networks for sending the video data, which their problem of being real-time is pronounced. At last, we present a method for ensuring the end-to-end quality of service at application layer level for adaptable sending of the video data at heterogeneous wireless networks. To do this, mechanism in different layers has been used. We have used the stop mechanism, the adaptation mechanism and the graceful degrade at the application layer, the multi-level congestion feedback mechanism in the network layer and connection cutting off decision mechanism in the link layer. At the end, the presented method and the achieved improvement is simulated and presented in the NS-2 software.

Keywords: Congestion, Handoff, Heterogeneous wireless networks, Adaptation mechanism, Stop mechanism, Graceful degrade.

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Authors: Siddhartha Bhattacharyya, Paramartha Dutta, Ujjwal Maulik, Prashanta Kumar Nandi

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A multilayer self organizing neural neural network (MLSONN) architecture for binary object extraction, guided by a beta activation function and characterized by backpropagation of errors estimated from the linear indices of fuzziness of the network output states, is discussed. Since the MLSONN architecture is designed to operate in a single point fixed/uniform thresholding scenario, it does not take into cognizance the heterogeneity of image information in the extraction process. The performance of the MLSONN architecture with representative values of the threshold parameters of the beta activation function employed is also studied. A three layer bidirectional self organizing neural network (BDSONN) architecture comprising fully connected neurons, for the extraction of objects from a noisy background and capable of incorporating the underlying image context heterogeneity through variable and adaptive thresholding, is proposed in this article. The input layer of the network architecture represents the fuzzy membership information of the image scene to be extracted. The second layer (the intermediate layer) and the final layer (the output layer) of the network architecture deal with the self supervised object extraction task by bi-directional propagation of the network states. Each layer except the output layer is connected to the next layer following a neighborhood based topology. The output layer neurons are in turn, connected to the intermediate layer following similar topology, thus forming a counter-propagating architecture with the intermediate layer. The novelty of the proposed architecture is that the assignment/updating of the inter-layer connection weights are done using the relative fuzzy membership values at the constituent neurons in the different network layers. Another interesting feature of the network lies in the fact that the processing capabilities of the intermediate and the output layer neurons are guided by a beta activation function, which uses image context sensitive adaptive thresholding arising out of the fuzzy cardinality estimates of the different network neighborhood fuzzy subsets, rather than resorting to fixed and single point thresholding. An application of the proposed architecture for object extraction is demonstrated using a synthetic and a real life image. The extraction efficiency of the proposed network architecture is evaluated by a proposed system transfer index characteristic of the network.

Keywords: Beta activation function, fuzzy cardinality, multilayer self organizing neural network, object extraction,

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Authors: R. Faiez, M. Mashhoudi, F. Najafi

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Implicit in most large-scale numerical analyses of the crystal growth from the melt is the assumption that the shape and position of the phase boundary are determined by the transport phenomena coupled strongly to the melt hydrodynamics. In the present numerical study, the interface shape-effect on the convective interactions in a Czochralski oxide melt is described. It was demonstrated that thermocapillary flow affects inversely the phase boundaries of distinct shapes. The inhomogenity of heat flux and the location of the stagnation point at the crystallization front were investigated. The forced convection effect on the point displacement at the boundary found to be much stronger for the flat plate interface compared to the cone-shaped one with and without the Marangoni flow.

Keywords: Computer simulation, fluid flow, interface shape, thermocapillary effect.

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Authors: S. Kikuchi, Y. Hashimoto, T. Takayama, T. Ikeda, Y. Murata

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Recently, lots of researchers are attracted to retrieving multimedia database by using some impression words and their values. Ikezoe-s research is one of the representatives and uses eight pairs of opposite impression words. We had modified its retrieval interface and proposed '2D-RIB'. In '2D-RIB', after a retrieval person selects a single basic music, the system visually shows some other music around the basic one along relative position. He/she can select one of them fitting to his/her intention, as a retrieval result. The purpose of this paper is to improve his/her satisfaction level to the retrieval result in 2D-RIB. One of our extensions is to define and introduce the following two measures: 'melody goodness' and 'general acceptance'. We implement them in different five combinations. According to an evaluation experiment, both of these two measures can contribute to the improvement. Another extension is three types of customization. We have implemented them and clarified which customization is effective.

Keywords: Multimedia database, impression-based retrieval, interface, satisfaction level.

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Authors: Ke Wang, Zhu Wang

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Coordinating and promoting urban and rural development has been a new round of institutional change in Zhejiang province since 2004. And this plan was fully implemented, which showed that the isolation between the urban and rural areas had gradually diminished. Little by little, an infiltration interface that is dynamic, flexible and interactive is formed, and this morphological structure starts to appear on the landscape form in the surrounding villages. In order to study the specific function and formation of the structure in the context of industrial revolution, Bimen village located on the interface between Anji Township, Huzhou and Yuhang District, Hangzhou is taken as the case. Anji township is in the cross area between Yangtze River delta economic circle and innovation center in Hangzhou. Awarded with ‘Chinese beautiful village’, Bimen has witnessed the growing process of infiltration in ecology, economy, technology and culture on the interface. Within the opportunity, Bimen village presents internal reformation to adapt to the energy exchange with urban areas. In the research, the reformation is to adjust the industrial structure, to upgrade the local special bamboo crafts, to release space for activities, and to establish infrastructures on the interface. The characteristic of an interface is elasticity achieved by introducing an Internet platform using ‘O2O’ agriculture method to connect cities and farmlands. There is a platform of this kind in Bimen named ‘Xiao Mei’. ‘Xiao’ in Chinese means small, ‘Mei’ means beautiful, which indicates the method to refine the landscape form. It turns out that the new agriculture mode will strengthen the interface by orienting the Third Party Platform upon the old dynamic basis and will bring new vitality for economy development in Bimen village. The research concludes opportunities and challenges generated by the evolution of the infiltration interface. It also proposes strategies for how to organically adapt to the urbanization process. Finally it demonstrates what will happen by increasing flexibility in the landscape forms of suburbs in the Bimen village.

Keywords: Bimen Village, infiltration interface, flexibility, suburban landscape form.

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Authors: Dhahri Maher, Aouinet Hana

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The presence of bubbles in the boundary layer introduces corrections into the log law, which must be taken into account. In this work, a logarithmic wall law was presented for bubbly two phase flows. The wall law presented in this work was based on the postulation of additional turbulent viscosity associated with bubble wakes in the boundary layer. The presented wall law contained empirical constant accounting both for shear induced turbulence interaction and for non-linearity of bubble. This constant was deduced from experimental data. The wall friction prediction achieved with the wall law was compared to the experimental data, in the case of a turbulent boundary layer developing on a vertical flat plate in the presence of millimetric bubbles. A very good agreement between experimental and numerical wall friction prediction was verified. The agreement was especially noticeable for the low void fraction when bubble induced turbulence plays a significant role.

Keywords: Bubbly flows, log law, boundary layer.

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Authors: Saroj Kumar Sarangi, M. C. Ray

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This paper deals with the analysis of active constrained layer damping (ACLD) of doubly curved laminated composite shells using active fiber composite (AFC) materials. The constraining layer of the ACLD treatment has been considered to be made of the AFC materials. A three dimensional energy based finite element model of the smart doubly curved laminated composite shell integrated with a patch of such ACLD treatment has been developed to demonstrate the performance of the patch on enhancing the damping characteristics of the doubly curved laminated composite shells. Particular emphasis has been placed on studying the effect of variation of piezoelectric fiber orientation angle in the constraining AFC layer on the control authority of the ACLD patch.

Keywords: Active constrained layer damping, Active fibercomposites, Finite element modeling, First order shear deformationtheory.

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Authors: Watcharawalee Lertlum, Borworn Papasratorn

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Conventional WBL is effective for meaningful student, because rote student learn by repeating without thinking or trying to understand. It is impossible to have full benefit from conventional WBL. Understanding of rote student-s intention and what influences it becomes important. Poorly designed user interface will discourage rote student-s cultivation and intention to use WBL. Thus, user interface design is an important factor especially when WBL is used as comprehensive replacement of conventional teaching. This research proposes the influencing factors that can enhance student-s intention to use the system. The enhanced TAM is used for evaluating the proposed factors. The research result points out that factors influencing rote student-s intention are Perceived Usefulness of Homepage Content Structure, Perceived User Friendly Interface, Perceived Hedonic Component, and Perceived (homepage) Visual Attractiveness.

Keywords: E-learning, Web-Based learning, Intention to use, Rote student, Influencing.

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Authors: M. Areekijseree, M. Pumipaiboon, S. Nuamsukon, K. Kittiwattanawong, C. Thongchai, S. Sikiwat, T. Chuen-Im

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There are few studies on eggshell of leatherback turtle which is endangered species in Thailand. This study was focusing on the ultrastructure and elemental composition of leatherback turtle eggshells collected from Andaman Sea Shore, Thailand during the nesting season using scanning electron microscope (SEM). Three eggshell layers of leatherback turtle; the outer cuticle layer or calcareous layer, the middle layer or middle multistrata layer and the inner fibrous layer were recognized. The outer calcareous layer was thick and porosity which consisted of loose nodular units of various crystal shapes and sizes. The loose attachment between these units resulted in numerous spaces and openings. The middle layer was compact thick with several multistrata and contained numerous openings connecting to both outer cuticle layer and inner fibrous layer. The inner fibrous layer was compact and thin, and composed of numerous reticular fibers. Energy dispersive X-ray microanalysis detector revealed energy spectrum of X-rays character emitted from all elements on each layer. The percentages of all elements were found in the following order: carbon (C) > oxygen (O) > calcium (Ca) > sulfur (S) > potassium (K) > aluminum (Al) > iodine (I) > silicon (Si) > chlorine (Cl) > sodium (Na) > fluorine (F) > phosphorus (P) > magnesium (Mg). Each layer consisted of high percentage of CaCO3 (approximately 98%) implying that it was essential for turtle embryonic development. A significant difference was found in the percentages of Ca and Mo in the 3layers. Moreover, transition metal, metal and toxic non-metal contaminations were found in leatherback turtle eggshell samples. These were palladium (Pd), molybdenum (Mo), copper (Cu), aluminum (Al), lead (Pb), and bromine (Br). The contamination elements were seen in the outer layers except for Mo. All elements were readily observed and mapped using Smiling program. X-ray images which mapped the location of all elements were showed. Calcium containing in the eggshell appeared in high contents and was widely distributing in clusters of the outer cuticle layer to form CaCO3 structure. Moreover, the accumulation of Na and Cl was observed to form NaCl which was widely distributing in 3 eggshell layers. The results from this study would be valuable on assessing the emergent success in this endangered species.

Keywords: Leatherback turtle (Dermochelys coriacea), SEM (SEI/EDX), turtle eggshell.

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Authors: Shafiq Ur Rehman, Jane-Lisa Coughlan

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One challenging direction of mobile commerce (mcommerce) that is getting a great deal of attention globally is mobile financing. The smart-phone and PDA users all around the world are facing difficulties to become accustomed and trust in m-commerce. The main rationale can be the slow variation and lack of trust in mobile payment systems. Mobile payment systems that are in use need to be more effective and efficient. This paper proposes: the interface design is not the only factor affecting the m-commerce adoption and lack of trust; in fact it is the combined effect of interface usability and trustworthy mobile payment systems, because it-s the money that the user has to spend at the end of the day, which the user requires to get transferred securely. The purpose of this research is to identify the problems regarding the trust and adaption of m-commerce applications by mobile users and to provide the best possible solution with respect to human computer interaction (HCI) principles.

Keywords: m-commerce, usability, mobile payment method, interface design.

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Authors: Mustafa Resa Becan

Abstract:

Sliding mode control with a fuzzy boundary layer is presented to hydraulic position control problem in this paper. A nonlinear hydraulic servomechanism which has an asymmetric cylinder is modeled and simulated first, then the proposed control scheme is applied to this model versus the conventional sliding mode control. Simulation results proved that the chattering free position control is achieved by tuning the fuzzy scaling factors properly.

Keywords: Hydraulic servomechanism, position control, sliding mode control, chattering, fuzzy boundary layer.

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Authors: Shidvash Vakilipour, Scott Ormiston, Masoud Mohammadi, Rouzbeh Riazi, Kimia Amiri, Sahar Barati

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Two-phase and multi-phase flows are common flow types in fluid mechanics engineering. Among the basic and applied problems of these flow types, two-phase parallel flow is the one that two immiscible fluids flow in the vicinity of each other. In this type of flow, fluid properties (e.g. density, viscosity, and temperature) are different at the two sides of the interface of the two fluids. The most challenging part of the numerical simulation of two-phase flow is to determine the location of interface accurately. In the present work, a coupled interface tracking algorithm is developed based on Arbitrary Lagrangian-Eulerian (ALE) approach using a cell-centered, pressure-based, coupled solver. To validate this algorithm, an analytical solution for fully developed two-phase flow in presence of gravity is derived, and then, the results of the numerical simulation of this flow are compared with analytical solution at various flow conditions. The results of the simulations show good accuracy of the algorithm despite using a nearly coarse and uniform grid. Temporal variations of interface profile toward the steady-state solution show that a greater difference between fluids properties (especially dynamic viscosity) will result in larger traveling waves. Gravity effect studies also show that favorable gravity will result in a reduction of heavier fluid thickness and adverse gravity leads to increasing it with respect to the zero gravity condition. However, the magnitude of variation in favorable gravity is much more than adverse gravity.

Keywords: Coupled solver, gravitational force, interface tracking, Reynolds number to Froude number, two-phase flow.

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Authors: M. Ferguson, T. Konkova, I. Violatos

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Microstructure analysis of additively manufactured (AM) materials is an important step in understanding the interrelationship between mechanical properties and materials performance. Literature on the effect of a laser-based AM process parameters on the microstructure in the substrate-deposit interface is limited. The interface region, the adjoining area of substrate and deposit, is characterized by the presence of the fusion zone (FZ) and heat affected zone (HAZ) experiencing rapid thermal gyrations resulting in thermal induced transformations. Inconel 718 was utilized as a work material for both the substrate and deposit. Three blocks of Inconel 718 material were deposited by Direct Energy Deposition (DED) using three different laser powers, 550W, 750W and 950W, respectively. A coupled thermo-mechanical transient approach was utilized to correlate temperature history to the evolution of microstructure. Thermal history of the deposition process was monitored with the thermocouples installed inside the substrate material. Interface region of the blocks were analysed with Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) including electron back-scattered diffraction (EBSD) technique. Laser power was found to influence the dissolution of intermetallic precipitated phases in the substrate and grain growth in the interface region. Microstructure and thermal history data were utilized to draw conclusive comparisons between the investigated process parameters.

Keywords: Additive manufacturing, direct energy deposition, electron back-scatter diffraction, finite element analysis, Inconel 718, microstructure, optical microscopy, scanning electron microscopy, substrate-deposit interface region.

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Authors: Young-Seok Choi

Abstract:

In healthy humans, the cortical brain rhythm shows specific mu (~6-14 Hz) and beta (~18-24 Hz) band patterns in the cases of both real and imaginary motor movements. As cerebellar ataxia is associated with impairment of precise motor movement control as well as motor imagery, ataxia is an ideal model system in which to study the role of the cerebellocortical circuit in rhythm control. We hypothesize that the EEG characteristics of ataxic patients differ from those of controls during the performance of a Brain-Computer Interface (BCI) task. Ataxia and control subjects showed a similar distribution of mu power during cued relaxation. During cued motor imagery, however, the ataxia group showed significant spatial distribution of the response, while the control group showed the expected decrease in mu-band power (localized to the motor cortex).

Keywords: Brain-computer interface, EEG, modulation, ataxia.

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Authors: T. Zalabsky, P. Bezousek, T. Shejbal

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The paper describes new concept of the ribbon beam antenna for RFID technology. Antenna is located near to railway lines to monitor tags situated on trains. Antenna works at 2.45 GHz and it is fabricated by microstrip technology. Antenna contains two same mirrored parts having the same radiation patterns. Each part consists of three dielectric layers. The first layer has on one side radiation elements. The second layer is only for mechanical construction and it sets optimal electromagnetic field for each radiating elements. The third layer has on its top side a ground plane and on the bottom side a microstrip circuit used for individual radiation elements feeding.

Keywords: RFID, cosecant radiation pattern, ribbon beam, patch antenna, microstrip.

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Authors: Tae Yun Chung, Jungho Moon, Tae Kwon Ha

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Al/Cu clad sheet has been fabricated by using differential speed rolling (DSR) process, which caused severe shear deformation between Al and Cu plate to easily bond to each other. Rolling was carried out at 100 and 150oC with speed ratios from 1.4 to 2.2, in which the total thickness reduction was in the range between 14 and 46%. Interfacial microstructure and mechanical properties of Al/Cu clad were investigated by scanning electron microscope equipped with energy dispersive X-ray detector, and tension tests. The DSR process was very effective to provide a good interface for atoms diffusion during subsequent annealing. The strength of bonding was higher with the increasing speed ratio. Post heat treatment enhanced the mechanical properties of clad sheet by forming intermetallic compounds in the interface area. 

Keywords: Aluminum/Copper clad sheet, Differential speed rolling, Interface microstructure, Annealing, Tensile test.

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Authors: Donna M. G. Comissiong, Tyrone D. Dass, Harold Ramkissoon, Alana R. Sankar

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The B'enard-Marangoni thermal instability problem for a viscoelastic Jeffreys- fluid layer with internal heat generation is investigated. The fluid layer is bounded above by a realistic free deformable surface and by a plane surface below. Our analysis shows that while the internal heat generation and the relaxation time both destabilize the fluid layer, its stability may be enhanced by an increased retardation time.

Keywords: Viscoelastic fluid, Jeffreys' model, Maxwell model, internal heat generation, retardation time, relaxation time.

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Authors: M. Ertas, A. C. Onel, G. Ekinci, B. Toydemir, S. Durdu, M. Usta, L. Colakerol Arslan

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To develop AZ91D magnesium alloys with improved properties, we have applied TiN and VN/TiN multilayer coatings using DC magnetron sputter technique. Coating structure, surface morphology, chemical bonding and corrosion resistance of coatings were analyzed by x-ray diffraction (XRD), scanning electron microscope (SEM), x-ray photoelectron spectroscopy (XPS), and tafel extrapolation method, respectively. XPS analysis reveal that VN overlayer reacts with oxygen at the VN/TiN interface and forms more stable TiN layer. Morphological investigations and the corrosion results show that VN/TiN multilayer thin film coatings are quite effective to optimize the corrosion resistance of Mg alloys.

Keywords: AZ91D Mg alloys, High corrosion resistance, Transition metal nitride coatings, Magnetron sputter.

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Authors: Guohua Tu, Zhi Fu, Zhiwei Hu, Neil D Sandham, Jianqiang Chen

Abstract:

Tripping of boundary-layers from laminar to turbulent flow, which may be necessary in specific practical applications, requires high amplitude disturbances to be introduced into the boundary layers without large drag penalties. As a possible improvement on fixed trip devices, a technique based on vortex shedding for enhancing supersonic flow transition is demonstrated in the present paper for a Mach 1.5 boundary layer. The compressible Navier-Stokes equations are solved directly using a high-order (fifth-order in space and third-order in time) finite difference method for small-scale cylinders suspended transversely near the wall. For cylinders with proper diameter and mount location, asymmetry vortices shed within the boundary layer are capable of tripping laminar-turbulent transition. Full three-dimensional simulations showed that transition was enhanced. A parametric study of the size and mounting location of the cylinder is carried out to identify the most effective setup. It is also found that the vortex shedding can be suppressed by some factors such as wall effect.

Keywords: Boundary layer instability, boundary layer transition, vortex shedding, supersonic flows, flow control.

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