Search

Accurate simulation of unsteady turbulent flow is critical for improved design of greener aircraft that are quieter and more fuel-efficient. We demonstrate application of PyFR, a Python based computational fluid dynamics solver, to petascale simulation of such flow problems. Rationale behind algorithmic choices, which offer increased levels of accuracy and enable sustained computation at up to 58% of peak DP-FLOP/s on unstruc- tured grids, will be discussed in the context of modern hardware. A range of software innovations will also be detailed, including use of runtime code generation, which enables PyFR to efficiently target multiple platforms, including heterogeneous systems, via a single implemen- tation. Finally, results will be presented from a full- scale simulation of flow over a low-pressure turbine blade cascade, along with weak/strong scaling statistics from the Piz Daint and Titan supercomputers, and performance data demonstrating sustained computation at up to 13.7 DP-PFLOP/s.

Field robot represented by excavator can be applied for various working in manufacturing, construction, agriculture etc. Because of the flexibility of its multi-joint mechanism and the high power of hydraulic actuators. Since the excavator operates in the hazardous working circumstance, operators exposed in harmful environment. Therefore, automation system has been investigated to protect from the harmful environment. In this paper, the method to construct the remote control system is proposed. The remote control system is consisted of a manual and auto mode. Manual mode controls a hydraulic cylinder as open loop control. And auto mode controls the end effecter of excavator using tracking control system. The efficiency of remote control system was evaluated through the field test.

A low-power sensor node in WSN requires minimum consumption of energy. It is essential to establish key to reduce the effect when the sensor node is revealed. This paper propose the protocol of pairwise key establishment between sensor node. The proposed method increases the availability by clustering the network in three dimensional, which has smaller number of path and better energy efficiency than the plane allocation. This paper discusses the key management for secure communication between sensor nodes after sensor allocation. We propose the protocol of pairwise key establishment scheme using bivariate polynomial based on cluster in order to safety against attack by revealing of node. The proposed method guarantee the availability by clustering the network in three dimensional, which has smaller number of path and better energy efficiency.

In this study, we first present the experimental results that regard the direct growth of CNTs on a conical-type tungsten (W) tip and their electron emission properties, in terms of the catalyst materials such as a nickel (Ni) and a cobalt (Co) as well as their composition ratios. Sharpening of W-tips was done by electrochemical etch and their diameters were controlled to range from 5 mum down to sub-mum. The co-sputtering method using Ni and Co targets was used to deposit the catalyst layers with various composition ratios of Ni and Co metals. The composition ratio of the co-sputtered catalysts was evaluated by using an energy dispersive X-ray spectroscopy (EDS, Oxford). CNTs were grown by inductively coupled plasma-chemical vapor deposition (ICP-CVD).

The amount of oxygen, which is used as an additive gas in preparing ZnO films by RF magnetron sputtering, has been changed during deposition in the range of O/sub 2//(Ar+O/sub 2/) = 10-90 % and its influence on film properties has been examined. X-ray diffraction (XRD) and atomic force microscope (AFM) studies present an optimal condition for oxygen addition at which ZnO films with desirable properties, such as highly preferred [002] orientation, excellent crystallinity, and smooth film surface, can be grown. The effect of electric bias (DC) applied to the substrate (from -80 V to +80 V) has also been analyzed in terms of the crystal quality and surface roughness of ZnO films. In addition, film bulk acoustic resonators (FBARs) with configuration of Al/ZnO/Al/Si(111) are fabricated and the influence of electric bias on their frequency response characteristics. The result shows that DC substrate biasing may improve the crystal quality of deposited ZnO films, and consequently enhance the electromechanical coupling capability of ZnO-based FBARs.

A two-step deposition method using RF reactive magnetron sputtering is proposed to obtain AlN thin films of high quality for film bulk acoustic resonators (FBARs). The 1/sup st/ deposition step is focused on lowering the surface roughness of the AlN films. In the 2/sup nd/ deposition step, the RF power and the working pressure are controlled to enhance the c-axis preferred growth of the AlN films. It is seen by monitoring the X-ray diffraction (XRD) spectra that the films deposited by the two-step method reveal an improved c-axis preferred orientation. Atomic force microscopy (AFM) images show that the surface roughness of the films is drastically reduced by adopting two-step deposition. It is also found, from the measurement of the frequency response characteristics of the AlN-FBARs, that the devices based on AlN films prepared using the two-step method reveal better device performance in return loss and electro-mechanical coupling coefficient (k/sub t//sup 2/).

Film bulk acoustic resonators (FBARs) with an Al/AlN/Mo/Si (111) configuration are fabricated. In particular, the effects of deposition conditions on material properties of AlN films grown on Mo/Si substrate as well as the performance of FBARs are studied. Piezoelectric AlN films are deposited using RF magnetron sputtering at RF power=250 W/spl sim/600 W, N/sub 2//Ar ratio=5/25/spl sim/25/5, working pressure=5 mTorr, substrate temperature=250/spl deg/C. For all the deposited AlN films, the X-ray diffraction (XRD) spectra and full width at half maximum (FWHM) of rocking curves are measured in terms of the deposition conditions, to characterize the c-axis preferred orientation and crystal quality. The frequency response characteristics (S/sub 11/) of the fabricated FBARs are also measured. The experimental results indicate that the characteristics of FBARs can be determined by the material properties of the AlN films. Furthermore, the theoretical relation ship between the impedance parameters (R/sub m/) of the BVD model and the AlN properties has been established.

Polycrystalline ZnO thin films are deposited on SiO/sub 2//Si(100) substrate using RF magnetron sputtering. The film deposition performed in this research is composed of the following two procedures; 1/sup st/-deposition for 30 min without oxygen at 100 W and 2/sup nd/-deposition with oxygen in the range O/sub 2//(Ar+O/sub 2/)=10/spl sim/50%. Deposited ZnO films reveal a strongly c-axis preferred-orientation (the corresponding texture coefficient /spl sim/100%) as well as a high resistivity (>10/sup 7//spl Omega/cm). It is also observed that the crystallite size of ZnO is noticeably increased by thermal-annealing. In addition, surface acoustic wave (SAW) devices are also fabricated by using a lift-off method, with the configuration of IDT/ZnO/SiO/sub 2//Si(100). Frequency response characteristics (including S/sub 21/) of fabricated SAW devices are measured and device parameters including insertion losses and side-lobe rejection level estimated from frequency response are compared.

In this paper, we present the effects of the thermal annealing of the W/SiO/sub 2/ multi-layer Bragg reflectors on the resonance characteristics of the ZnO-based film bulk acoustic resonator (FBAR) devices and the use of the cobalt (Co) electrodes instead of the aluminum (Al) electrodes to optimize the FBAR for RF filter applications. The resonance characteristics could be significantly improved by the thermal annealing and using the Co as the electrodes in FBAR devices. The FBAR devices with the Bragg reflectors annealed at 400/spl deg/C/30 min show excellent resonance characteristics in term of the return loss and Q-factor.