Numerical simulation of laminar flow past a circular cylinder with slip conditions

The no‐slip condition is an assumption that cannot be derived from first principles and a growing number of literatures replace the no‐slip condition with partial‐slip condition, or Navier‐slip condition. In this study, the influence of partial‐slip boundary conditions on the laminar flow properties past a circular cylinder was examined. Shallow‐water equations are solved by using the finite element method accommodating SU/PG scheme. Four Reynolds numbers (20, 40, 80, and 100) and six slip lengths were considered in the numerical simulation to investigate the effects of slip length and Reynolds number on characteristic parameters such as wall vorticity, drag coefficient, separation angle, wake length, velocity distributions on and behind the cylinder, lift coefficient, and Strouhal number. The simulation results revealed that as the slip length increases, the drag coefficient decreases since the frictional component of drag is reduced, and the shear layer developed along the cylinder surface tends to push the separation point away toward the rear stagnation point so that it has larger separation angle than that of the no‐slip condition. The length of the wake bubble zone was shortened by the combined effects of the reduced wall vorticity and wall shear stress which caused a shift of the reattachment point closer to the cylinder. The frequency of the asymmetrical vortex formation with partial slip velocity was increased due to the intrinsic inertial effect of the Navier‐slip condition. Copyright © 2011 John Wiley & Sons, Ltd.     

Optimization of gate poly TAB size and reliability on short channel pMOSFET

In this report, the effective gate tab size on pMOSFET to reduce HEIP degradation was investigated. As a result, the effects of tab size of STI edge have been studied and we could propose a design guide taking into account both reliability and process margin as a part of the design for reliability (DFR).     

Efficient two-stage frequency-domain equalisation for mitigating MAI in CDMA systems

An efficient two-stage frequency-domain equalisation (TS-FDE) is proposed, in order to mitigate the effect of multiple access interference (MAI) in code division multiple access (CDMA) systems having no cyclic-prefix (CP). In TS-FDE, the first stage performs channel equalisation and signal detection. Utilising the detected signal and a channel response, the second stage constructs the circularity of a channel matrix for a received signal, and then it performs once more the channel equalisation like an FDE using the CP. The MAI mitigating capability of the TS-FDE is evaluated in a mobile channel.     

Resistance-switching Characteristics of polycrystalline Nb/sub 2/O/sub 5/ for nonvolatile memory application

The resistance switching characteristics of polycrystalline Nb/sub 2/O/sub 5/ film prepared by pulsed-laser deposition (PLD) were investigated for nonvolatile memory application. Reversible resistance-switching behavior from a high resistance state to a lower state was observed by voltage stress with current compliance. The reproducible resistance-switching cycles were observed and the resistance ratio was as high as 50-100 times. The resistance switching was observed under voltage pulse as short as 10 ns. The estimated retention lifetime at 85/spl deg/C was sufficiently longer than ten years. Considering its excellent electrical and reliability characteristics, Nb/sub 2/O/sub 5/ shows strong promise for future nonvolatile memory applications.     

Efficient classification of ISAR images

In this paper, we propose a method to classify inverse synthetic aperture radar images from different targets. Our approach can provide efficient features for classification by the combined use of a polar mapping procedure and a well-designed classifier. The resulting feature vectors are able to meet the requirements that efficient features should have: invariance with respect to rotation and scale, small dimensionality, as well as highly discriminative information. Typical experimental examples of the proposed method are provided and discussed.     

An Enhanced Location‐Based Location Update Scheme in Mobile Cellular Networks

In this study, we consider a location‐based location update (LU) scheme. We propose an enhanced LU (ELU) scheme that can store more cells to reduce the location update cost of the LU scheme and show that the ELU scheme always outperforms the LU scheme. Our scheme can be easily implemented in actual cellular systems.