1,825 research outputs found
Dual-band internal WLAN antenna for 2.4/5 GHz laptop PC applications
No full textThis paper presents a dual-band internal WLAN PIFA for 2.4/5 GHz laptop applications in consideration of the influences of laptop housing and LCD. The prototype antenna is modified when installed along the perimeter of the display panel of the laptop housing. The proposed antenna has a small ground plane and achieves an impedance bandwidth of 250 MHz (2.37-2.62 GHz) in Bluetooth band and 950 MHz (4.98-5.93 GHz) near 5 GHz in WLAN band within 2:1 voltage standing wave ratio (VSWR). It also shows good antenna gain with small volume. These features make it an alternative for use in dual-band WLAN antennas. Design details for the proposed antenna in the case of the antenna itself and the application of laptop PC housing are described, and experimental results of the antenna achievements are investigated and discussed. (c) 2006 Wiley Periodicals, Inc
The Electrical, Optical and Structural Characteristics of N-type Microcrystalline Silicon Thin Films Deposited by TCP-CVD
No full textAutomatic gain-controlled bidirectional add/drop amplifier module for dynamically reconfigurable bidirectional WDM networks
No full text
Optical and Electrical Properties of Boron Doped Amorphous Silicon-Carbon Thin Films by TCP-CVD
No full textHierarchical fuzzy segmentation of brain MR images
No full textIn brain magnetic resonance (MR) images, image segmentation and 3D visualization are very useful tools for the diagnosis of abnormalities. Segmentation of white matter (WM), gray matter (GM), and cerebrospinal fluid (CSF) is the basic process for 3D visualization of brain MR images. Of the many algorithms, the fuzzy c-means (FCM) technique has been widely used for segmentation of brain MR images. However, the FCM technique does not yield sufficient results under radio frequency (RF) nonuniformity. We propose a hierarchical FCM (HFCM), which provides good segmentation results under RF nonuniformity and does not require any parameter setting. We also generate Talairach templates of the brain that are deformed to 3D brain MR images. Using the deformed templates, only the cerebrum region is extracted from the 3D brain MR images. Then, the proposed HFCM partitions the cerebrum region into WM, GM, and CSF. (C) 2003 Wiley Periodicals, Inc
Inhibition effect of methanogenesis on electricity generation from synthetic fermented effluent using microbial fuel cells
No full textAll-to-all personalized communication in multidimensional torus and mesh networks
No full textAll-to-all personalized communication commonly occurs in many important parallel algorithms, such as FFT and matrix transpose. This paper presents new algorithms for all-to-all personalized communication or complete exchange in multidimensional torus- or mesh-connected multiprocessors. For an R x C torus or mesh where R less than or equal to C, the proposed algorithms have time complexities of O(C) message startups and O(RC(2)) message transmissions. The algorithms for three- or higher-dimensional tori or meshes follow a similar structure. Unlike other existing message-combining algorithms in which the number of nodes in each dimension should be a power-of-two and square. the proposed algorithms accommodate non-power-of-two tori or meshes where the number of nodes In each dimension need not be power-of-two and square. In addition, destinations remain fixed over a larger number of steps in the proposed algorithms, thus making them amenable to optimizations. Finally, the data structures used are simple, hence making substantial savings of message-rearrangement time.X1122sciescopu
Effects of atomistic defects on coherent electron transmission in Si nanowires: Full band calculations
No full textThe effects of atomistic imperfections on coherent electron transmission in Si[100] quantum wires a few nanometers wide are investigated using a tight-binding Green function approach. We find a significant suppression in the electron transmission by atomistic imperfections in these extremely narrow wires. Multiple conductance peaks or oscillations can be easily developed by the presence of only several vacancy defects, which can lead to a finite zero-conductance region around the subband edge. Several substitutional defects and surface dangling bonds generally result in decreased, oscillatory conductances with more significant effects found in narrower wires. (C) 2001 American Institute of Physics
An efficient multicast routing protocol in wireless mobile networks
No full textProviding multicast service to mobile hosts in wireless mobile networking environments is difficult due to frequent changes of mobile host location and group membership. If a conventional multicast routing protocol is used in wireless mobile networks, several problems may be experienced since existing multicast routing protocols assume static hosts when they construct the multicast delivery tree. To overcome the problems, several multicast routing protocols for mobile hosts have been proposed. Although the protocols solve several problems inherent in multicast routing proposals for static hosts, they still have problems such as non-optimal delivery path, datagram duplication, overheads resulting from frequent reconstruction of a multicast tree, etc. In this paper, we summarize these problems of multicast routing protocols and propose an efficient multicast routing protocol based on IEFT mobile IP in wireless mobile networks. The proposed protocol introduces a multicast agent, where a mobile host receives a tunneled multicast datagram from a multicast agent located in a network close to it or directly from the multicast router in the current network. While receiving a tunneled multicast datagram from a remote multicast agent, the local multicast agent may start multicast join process, which makes the multicast delivery route optimal. The proposed protocol reduces data delivery path length and decreases the amount of duplicate copies of multicast datagrams. We examined and compared the performance of the proposed protocol and existing protocols by simulation under various environments and we got an improved performance over the existing proposals.X1139sciescopu
- …
