Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

2008

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 4171 - 4190 of 4190

Full-Text Articles in Engineering

An Improved Fec Scheme For Mobile Wireless Communication At Vehicular Speeds, Iftekhar Ahmad, Daryoush Habibi, Ziaur Rahman Jan 2008

An Improved Fec Scheme For Mobile Wireless Communication At Vehicular Speeds, Iftekhar Ahmad, Daryoush Habibi, Ziaur Rahman

Research outputs pre 2011

WiMAX has emerged as a promising wireless communication technology with potential to deliver high throughput and guaranteed quality of service to the end applications. Recent studies suggest that while WiMAX (802.16e) is capable of delivering a data rate of up to 75 Mbps for fixed wireless communications, data rate decreases drastically for mobile wireless communications, often providing a data rate less than 1 Mb/s when the mobile nodes travel at vehicular speeds. High bit error rate caused at high vehicular speeds is the key reason for low throughput. In noisy mobile communication environments, standard error control mechanisms like the transmission …

Go to article

Performance Evaluation Of Ieee 802.15.4 For Mobile Sensor Network, Kartinah Zen, Daryoush Habibi, Alexander Rassau, Iftekhar Ahmad Jan 2008

Performance Evaluation Of Ieee 802.15.4 For Mobile Sensor Network, Kartinah Zen, Daryoush Habibi, Alexander Rassau, Iftekhar Ahmad

Research outputs pre 2011

The IEEE 802.15.4 standard medium access control (MAC) protocol for low rate wireless personal area networks (LRWPAN) is design mainly for static sensor networks and its capability to support mobile sensor networks has not yet been established. To the best knowledge of authors, this is the first paper that evaluates the suitability of IEEE 802.15.4 MAC in mobile sensor networks environment. We evaluate the performance based on node's speed and beacon order, and observe the effect on energy usage, packet delivery ratio and time required to associate with its coordinator. From the experiment we observe that the moving nodes experienced …

Go to article

Improving Mobile Sensor Connectivity Time In The Ieee 802.15.4 Networks, Kartinah Zen, Daryoush Habibi, Iftekhar Ahmad Jan 2008

Improving Mobile Sensor Connectivity Time In The Ieee 802.15.4 Networks, Kartinah Zen, Daryoush Habibi, Iftekhar Ahmad

Research outputs pre 2011

In the IEEE 802.15.4 medium access control (MAC) protocol for wireless sensor networks, a sensor node needs to associate with a coordinator before it starts sending or receiving data. The sensor node will mostly choose the nearest coordinator to associate with. However, this method is not suitable for a constantly moving sensor node because it will end up switching coordinators too often due to short connectivity time. The IEEE 802.15.4 has a simplistic and inadequate method of choosing a coordinator in this context. In this paper, we introduce a method to increase the mobile sensor node connectivity time with its …

Go to article

Self-Restraint Admission Control For Ad-Hoc Wlans, Hushairi Zen, Daryoush Habibi, Iftekhar Ahmad Jan 2008

Self-Restraint Admission Control For Ad-Hoc Wlans, Hushairi Zen, Daryoush Habibi, Iftekhar Ahmad

Research outputs pre 2011

Admission control is an important mechanism for sustaining throughput and supporting quality of service (QoS) for real-time traffic in a wireless local area network (WLAN). In an adhoc WLAN scenario where no access point (AP) is available, admission control has to be self-managed by each node. We propose a self-restraining admission control mechanism that works by monitoring the congestion level of the network in the adhoc WLAN. Wireless nodes can listen to all nodes within their range and be aware of the collision rates. A node wishing to join the network measures the current collision rate, and predicts the post-admission …

Go to article

Converging Voice, Video And Data In Wlan With Qos Support, Hushairi Zen, Daryoush Habibi, Justin Wyatt, Iftekhar Ahmad Jan 2008

Converging Voice, Video And Data In Wlan With Qos Support, Hushairi Zen, Daryoush Habibi, Justin Wyatt, Iftekhar Ahmad

Research outputs pre 2011

Providing quality of service (QoS) for converging traffic in wireless local area network (WLAN) is still a major issue for the researchers and industries. Due to the limited bandwidth and exposure to unpredictable interferences in a wireless environment, efficient management and optimization of the access protocols are essential to provide acceptable QoS for real-time traffic and fairness to best-effort traffic. In this paper, we investigate the throughput and delay performance of the legacy IEEE 802.11 and the 802.11e when carrying converging data in WLAN. We evaluate our recently proposed protocol known as wireless token network protocol (WTN) and show that …

Go to article

Novel Broadband Reconfigurable Optical Add-Drop Multiplexer Employing Custom Fiber Arrays And Opto-Vlsi Processors, Feng Xiao, Budi Juswardy, Kamal Alameh, Yong Tak Lee Jan 2008

Novel Broadband Reconfigurable Optical Add-Drop Multiplexer Employing Custom Fiber Arrays And Opto-Vlsi Processors, Feng Xiao, Budi Juswardy, Kamal Alameh, Yong Tak Lee

Research outputs pre 2011

A reconfigurable optical add/drop multiplexer (ROADM) structure based on using a custom-made fiber array and an Opto-VLSI processor is proposed and demonstrated. The fiber array consists of N pairs of angled fibers corresponding to N channels, each of which can independently perform add, drop, and thru functions through a reconfigurable Opto-VLSI beam steerer. Experimental results show that the ROADM structure can attain an average add, drop/thru insertion loss of 5.5 dB and a uniformity of 0.3 dB over a wide bandwidth from 1524 nm to 1576 nm, and a drop/thru crosstalk level as small as -40 dB.

Go to article

Development Of A Novel Finder Pattern For Effective Color 2d-Barcode Detection, Hiroko Kato, Keng T. Tan, Douglas Chai Jan 2008

Development Of A Novel Finder Pattern For Effective Color 2d-Barcode Detection, Hiroko Kato, Keng T. Tan, Douglas Chai

Research outputs pre 2011

With a camera mobile phone, which has become a "must-have" device, 2D-barcode works as an interface to bridge the physical and digital world. As the notion of ubiquitous computing has permeated, developing a new 2D-barcode and its applications has been a growing trend worldwide. A 2D-barcode symbol consists of two broad areas: data area and guide area. The components of the latter is collectively called "finder pattern" and used in locating the 2D-barcode symbol. The failure of finding the target symbol prevents a barcode reader from successfully decoding the barcode. Hence, designing a functional finder pattern is one of the …

Go to article

The Use Of Border In Colour 2d Barcode, Siong Ong, Douglas Chai, Keng T. Tan Jan 2008

The Use Of Border In Colour 2d Barcode, Siong Ong, Douglas Chai, Keng T. Tan

Research outputs pre 2011

In recent years, a trend has emerged in the use of colour to increase the data capacity of the 2D barcode. However the decoding of such colour barcode can be challenging in a mobile environment due to blurring effect that is commonly found in images captured by camera mobile phone. Blurring affects the synchronisation between the cells. It also causes the colour value of the cell to be wrongly interpreted. Hence, this paper proposes the use of border to improve the synchronisation and decoding. Three different types of border and the choice of its width will be investigated.

Go to article

Magnetic Field Sensors And Visualizers Using Magnetic Photonic Crystals, Mikhail Vasiliev, Kamal Alameh, Viatcheslav Kotov Jan 2008

Magnetic Field Sensors And Visualizers Using Magnetic Photonic Crystals, Mikhail Vasiliev, Kamal Alameh, Viatcheslav Kotov

Research outputs pre 2011

Magneto-optical imaging is widely used to observe the domain patterns in magnetic materials, visualize defects in ferromagnetic objects, and measure the spatial distribution of stray magnetic fields. Optimized 1D magneto-photonic crystals enable a significant increase in the sensitivity of magneto-optical sensors. The properties of such devices based on the optimized reflection (doubled Faraday rotation) mode and the use of 1D magnetic photonic crystals as sensors are discussed. Experimental results of the fabrication and characterization of ferrite-garnet layers possessing uniaxial magnetic anisotropy are shown, and an optimized film structure suitable for magneto-optical imaging is proposed.

Go to article

Photonic Nano-Structures For Water Quality Monitoring, Mikhail Vasiliev, Kamal Alameh Jan 2008

Photonic Nano-Structures For Water Quality Monitoring, Mikhail Vasiliev, Kamal Alameh

Research outputs pre 2011

We propose a new type of sensors suitable for water quality testing and for monitoring water contamination levels in domestic, industrial and environmental applications. The proposed sensing scheme uses Fourier transform cavity-enhanced absorption spectroscopy and novel compact sensing elements based on nanostructured photonic crystal-type optical coatings enabling the sensitive Fourier-domain processing methodology and maximising the absorption path length within the measurement system. The measurement scheme is shown to be suitable for the determination of small changes in the water absorption coefficients at a discrete set of wavelengths in the visible spectral region in response to small concentrations of pollutants with …

Go to article

Novel Magnetic Photonic Crystal Structures For Magnetic Field Sensors And Visualizers, Mikhail Vasiliev, Viatcheslav A. Kotov, Kamal E. Alameh, Vladimir I. Belotelov, Anatoly K. Zvezdin Jan 2008

Novel Magnetic Photonic Crystal Structures For Magnetic Field Sensors And Visualizers, Mikhail Vasiliev, Viatcheslav A. Kotov, Kamal E. Alameh, Vladimir I. Belotelov, Anatoly K. Zvezdin

Research outputs pre 2011

Optimized one-dimensional (1-D) magnetophotonic crystals greatly increase the sensitivity of magnetooptical sensors, which are widely used in magnetooptical imaging to observe the magnetic domain patterns in magnetic materials, to observe the vortex states in superconductors, to detect small bits in magnetooptical recording media, to visualize defects in ferromagnetic objects, and to measure the value and spatial distribution of stray magnetic fields. This paper examines the properties of such devices operating in the optimized reflection (doubled Faraday rotation) mode and discusses the use of 1-D magnetophotonic crystals as sensors.

Go to article

Doped Iron Garnet Materials For Magnetic Photonic Crystals, Mikhail Vasiliev, Kamal Alameh, Viatcheslav Kotov Jan 2008

Doped Iron Garnet Materials For Magnetic Photonic Crystals, Mikhail Vasiliev, Kamal Alameh, Viatcheslav Kotov

Research outputs pre 2011

We have established a set of technologies for the deposition and annealing of magneto-optic garnets for use in photonic crystals. Devices for sensing magnetic fields and polarisation control using reconfigurable photonic crystals are being developed.

Go to article

Double Boundary Trench Isolation Effects On A Stacked Gradient Homojunction Photodiode Array, Paul V. Jansz, Steven Hinckley Jan 2008

Double Boundary Trench Isolation Effects On A Stacked Gradient Homojunction Photodiode Array, Paul V. Jansz, Steven Hinckley

Research outputs pre 2011

The effect of the width of inter-pixel double boundary trench isolation on the response resolution of a two dimensional CMOS compatible stacked gradient homojunction photodiode array was simulated. Insulation and P-doped double boundary trench isolation were compared. Both geometries showed improved crosstalk suppression and enhanced sensitivity compared to photodiode geometries previously investigated, combined with a reduction in fabrication complexity for the insulation DBTI configuration.

Go to article

Microstructured Arrayed Microfluidic Waveguide Structure For Infrared Radiation Focusing And Transfer, Paul B. Laursen, Kamal Alameh, Mikhail Vasiliev, Nicholas C. Elliott Jan 2008

Microstructured Arrayed Microfluidic Waveguide Structure For Infrared Radiation Focusing And Transfer, Paul B. Laursen, Kamal Alameh, Mikhail Vasiliev, Nicholas C. Elliott

Research outputs pre 2011

A microstructured arrayed microfluidic waveguide structure for infrared radiation focussing and transfer is proposed and demonstrated. The arrayed waveguide structure comprises Masterbond UV-curable epoxy UV15 optimised using ZEMAX optical design software to achieve high efficiency of heat capture through far-infrared light focussing and subsequent absorption of the radiation on a centralised fluid medium. A high degree of alignment of the precision-positioned fluidic microchannels with the symmetry axes and the focal plane locations of the cylindrical microlens array is demonstrated, which maximises the efficiency of absorption of the incident IR light energy within the moving fluid. Observation of ink flows through …

Go to article

Acousto-Ultrasonic Optical Fiber Sensors: Overview And State-Of-The-Art, Graham Wild, Steven Hinckley Jan 2008

Acousto-Ultrasonic Optical Fiber Sensors: Overview And State-Of-The-Art, Graham Wild, Steven Hinckley

Research outputs pre 2011

This paper gives a review of acoustic and ultrasonic optical fiber sensors (OFSs). The review covers optical fiber sensing methods for detecting dynamic strain signals, including general sound and acoustic signals, high-frequency signals, i.e., ultrasonic/ultrasound, and other signals such as acoustic em

Go to article

An Intensiometric Detection System For Fibre Bragg Grating Sensors, Graham Wild, Steven Hinckley Jan 2008

An Intensiometric Detection System For Fibre Bragg Grating Sensors, Graham Wild, Steven Hinckley

Research outputs pre 2011

We present an intensiometric detection system for fibre Bragg grating sensors. The system is designed to directly detect intensity modulated signals, or to convert spectrally modulated signals into intensity modulated signals.

Go to article

A Micro-Photonic Stationary Optical Delay Line For Fibre Optic Time Domain Oct, Paul V. Jansz, Graham Wild, Steven Hinckley Jan 2008

A Micro-Photonic Stationary Optical Delay Line For Fibre Optic Time Domain Oct, Paul V. Jansz, Graham Wild, Steven Hinckley

Research outputs pre 2011

We present results for the characterisation of a micro-photonic stationary optical delay line. The delay line is intended to generate true time delays for a fibre optic based optical coherence tomography system.

Go to article

Creating Preservation-Ready Web Resources, Joan A. Smith, Michael L. Nelson Jan 2008

Creating Preservation-Ready Web Resources, Joan A. Smith, Michael L. Nelson

Computer Science Faculty Publications

There are innumerable departmental, community, and personal web sites worthy of long-term preservation but proportionally fewer archivists available to properly prepare and process such sites. We propose a simple model for such everyday web sites which takes advantage of the web server itself to help prepare the site's resources for preservation. This is accomplished by having metadata utilities analyze the resource at the time of dissemination. The web server responds to the archiving repository crawler by sending both the resource and the just-in-time generated metadata as a straight-forward XML-formatted response. We call this complex object (resource + metadata) a CRATE. …

Go to article

Emergent Behavior In Massively-Deployed Sensor Networks, Ekaterina Shurkova, Ruzana Ishak, Stephan Olariu, Shaharuddin Salleh Jan 2008

Emergent Behavior In Massively-Deployed Sensor Networks, Ekaterina Shurkova, Ruzana Ishak, Stephan Olariu, Shaharuddin Salleh

Computer Science Faculty Publications

The phenomenal advances in MEMS and nanotechnology make it feasible to build small devices, referred to as sensors that are able to sense, compute and communicate over small distances. The massive deployment of these small devices raises the fascinating question of whether or not the sensors, as a collectivity, will display emergent behavior, just as living organisms do. In this work we report on a recent effort intended to observe emerging behavior of large groups of sensor nodes, like living cells demonstrate. Imagine a massive deployment of sensors that can be in two states "red" and "blue". At deployment time …

Go to article

Efficient Corona Training Protocols For Sensor Networks, Alan A. Bertossi, Stephan Olariu, Cristina M. Pinotti Jan 2008

Efficient Corona Training Protocols For Sensor Networks, Alan A. Bertossi, Stephan Olariu, Cristina M. Pinotti

Computer Science Faculty Publications

Phenomenal advances in nano-technology and packaging have made it possible to develop miniaturized low-power devices that integrate sensing, special-purpose computing, and wireless communications capabilities. It is expected that these small devices, referred to as sensors, will be mass-produced and deployed, making their production cost negligible. Due to their small form factor and modest non-renewable energy budget, individual sensors are not expected to be GPS-enabled. Moreover, in most applications, exact geographic location is not necessary, and all that the individual sensors need is a coarse-grain location awareness. The task of acquiring such a coarse-grain location awareness is referred to as training. …

Go to article

First Prev