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Full-Text Articles in Engineering
Optimization Of Liquid-Crystal Spatial Light Modulator For Precise Phase Generation, Seow-Hwang Eng, Dong Mei Cai, Zhenglin Wang, Kamal Alameh, Wenhan Jiang
Optimization Of Liquid-Crystal Spatial Light Modulator For Precise Phase Generation, Seow-Hwang Eng, Dong Mei Cai, Zhenglin Wang, Kamal Alameh, Wenhan Jiang
Research outputs pre 2011
Spatial light modulators (SLMs) are recently emerging as wavefront generation or reconstruction devices. In this paper, we use a liquid-crystal SLM (LC-SLM) as a wavefront generation device through the modulation of the spatial phase distribution of an incident light beam. We characterize the phase modulation performance of the LC-SLM, and identified a polarization-configuration to minimize its amplitude modulation effects in order to maximize the contrast of reconstructed phase holograms. We also investigated the feasibility of determining the optical surface uniformity of the LC-SLM through computations of the interference fringes, and identified the disadvantages of this method. This new approach may …
Sampled Fiber Gratings For High-Resolution And High-Speed Photonic Signal Processing, Mingya Shen, Kamal Alameh
Sampled Fiber Gratings For High-Resolution And High-Speed Photonic Signal Processing, Mingya Shen, Kamal Alameh
Research outputs pre 2011
A novel sampled grating for high-resolution, highspeed signal processing is presented. Simulation based on Sinc2 sampled and rational sampled fiber grating modeling show that a large number of sub-ps time delay steps are attainable, corresponding to a sampling frequency in excess of 1THz. Design method is described for deriving sampling functions that meet specific true-time-delay profile requirements.
Integrated Broadband Microphotonics Beamformer For Adaptive Nulling In Smart Antennas, Budi Juswardy, Kamal Alameh, Yong Lee
Integrated Broadband Microphotonics Beamformer For Adaptive Nulling In Smart Antennas, Budi Juswardy, Kamal Alameh, Yong Lee
Research outputs pre 2011
This paper presents an integrated MicroPhotonic beamformer that processes RF-modulated optical signals to adaptively synthesise multiple broadband nulls in smart phased-array antennas, The beam former is designed to operate at centre frequency of 5.6 GHz with I GHz bandwidth. Designs of the different photonic and RF components are presented. Simulation results show that a 4-element MicroPhotonic broadband smart antenna beamformer operating in the 5.1-6,1- GHz range can generate three broadband nulls, with less than 1.121 0 beam squint.
Adaptive Segregation-Based Mac Protocol For Real-Time Multimedia Traffic In Wlans, Hushairi Zen, Daryoush Habibi, Alexander Rassau, Justin Wyatt
Adaptive Segregation-Based Mac Protocol For Real-Time Multimedia Traffic In Wlans, Hushairi Zen, Daryoush Habibi, Alexander Rassau, Justin Wyatt
Research outputs pre 2011
Wireless local area networks (WLANs) have become very popular both in private and public sectors. Despite the fast expansion of WLANs in various environments, quality of service (QoS) issues for multimedia applications in WLANs are not yet resolved. Multimedia applications contain traffic that are sensitive to delay and jitter and therefore a best-effort protocol such as the legacy IEEE 802.11 is not suitable. The 802.11e protocol provides prioritization and classification of traffic to offer better QoS for real-time services. However, it leaves the design and implementation of many important optimization features to vendors. In this paper we introduce a mechanism …
First Read Rate Analysis Of 2d-Barcodes For Camera Phone Applications As A Ubiquitous Computing Tool, Hiroko Kato, Keng T. Tan
First Read Rate Analysis Of 2d-Barcodes For Camera Phone Applications As A Ubiquitous Computing Tool, Hiroko Kato, Keng T. Tan
Research outputs pre 2011
This paper presents a detailed study on the first read rate (FRR) of seven 2D-barcodes currently used for camera phone applications. The study revealed a few surprising observations. Through our analysis, we identified three key factors to improve the robustness of 2D-barcode reading, the range of the reading distance and the stability of the readers. This will contribute to the widespread use of 2D-barcode mobile technology as a ubiquitous computing tool.
Opto-Vlsi-Based Reconfigurable Free Space Optical Interconnects Architecture, Muhsen Aljada, Kamal Alameh, Yong Lee, I-S Chung
Opto-Vlsi-Based Reconfigurable Free Space Optical Interconnects Architecture, Muhsen Aljada, Kamal Alameh, Yong Lee, I-S Chung
Research outputs pre 2011
This paper presents a short-distance reconfigurable high-speed optical interconnects architecture employing a Vertical Cavity Surface Emitting Laser (VCSEL) array, Opto-very-large-scale-integrated (Opto-VLSI) processors, and a photodetector (PD) array. The core component of the architecture is the Opto-VLSI processor which can be driven by digital phase steering and multicasting holograms that reconfigure the optical interconnects between the input and output ports. The optical interconnects architecture is experimentally demonstrated at 2.5 Gbps using high-speed 1×3 VCSEL array and 1×3 photoreceiver array in conjunction with two 1×4096 pixel Opto-VLSI processors. The minimisation of the crosstalk between the output ports is achieved by appropriately aligning …
Success? The Impact Of Involving Customers In E-Commerce Development, Julian Terry, Craig Standing
Success? The Impact Of Involving Customers In E-Commerce Development, Julian Terry, Craig Standing
Research outputs pre 2011
In e-commerce, customers have become Information System users. In this environment of non-mandatory usage, remote, untrained users need to quickly feel comfortable and satisfied with a site encounter. Throughout the literature for four decades, a commonly cited factor pertaining to system success has been user participation in the systems development process. Among other things this is likely to lead to increased user satisfaction and the perceived usefulness of the application. This study uses findings from thirty cases of recently completed e-commerce sites in which project leaders accounts of customer participation in e-commerce development activities are analysed, along with their perceptions …
Use Of The Wfg Toolkit And Pisa For Comparison Of Moeas, Lucas Bradstreet, Luigi Barone, Lyndon While, Simon Huband, Philip Hingston
Use Of The Wfg Toolkit And Pisa For Comparison Of Moeas, Lucas Bradstreet, Luigi Barone, Lyndon While, Simon Huband, Philip Hingston
Research outputs pre 2011
Understanding the behaviour of different optimisation algorithms is important in order to apply the best algorithm to a particular problem. The WFG toolkit was designed to aid this task for multi-objective evolutionary algorithms (MOEAs), offering an easily modifiable framework that allows practitioners the ability to test different features by "plugging" in different forms of transformations. In doing so, the WFG toolkit provides a set of problems that exhibit a variety of different characteristics. This paper presents a comparison between two state of the art MOEAs (NSGA-II and SPEA2) that exemplifies the unique capabilities of the WFG toolkit. By altering the …
Passive And Active Optical Bit-Pattern Recognition Structures For Multiwavelength Optical Packet Switching Networks, Muhsen Aljada, Kamal Alameh
Passive And Active Optical Bit-Pattern Recognition Structures For Multiwavelength Optical Packet Switching Networks, Muhsen Aljada, Kamal Alameh
Research outputs pre 2011
Next generation High-Speed optical packet switching networks require components capable of recognising the optical header to enable on-the-fly accurate switching of incoming data packets to their destinations. This paper experimentally demonstrates a comparison between two different optical header recognition structures; A passive structure based on the use of Fiber Bragg Gratings (FBGs), whereas the active structure employs Opto-VLSI processors that synthesise dynamic wavelength profile through digital phase holograms. The structures are experimentally demonstrated at 10Gbps. Performance comparison between the two structures is also discussed. These optical header recognition structures are attractive for multiwavelength optical network and applications.
Cylindrical Quasi-Cavity Waveguide For Static Wide Angle Pattern Projection, Kaveh Sahba, Kamal Alameh, Clifton Smith, Arie Paap
Cylindrical Quasi-Cavity Waveguide For Static Wide Angle Pattern Projection, Kaveh Sahba, Kamal Alameh, Clifton Smith, Arie Paap
Research outputs pre 2011
Beam deflection methods such as rotary mirrors and motorized turning optical heads suffer from a variety of electro-mechanical related problems which affect laser scanning performance. These include wobble, jitter, wear, windage and synchronization issues. A novel optical structure consisting of two concentric and cylindrical interfaces with unique optical coating properties for the static projection of a laser spot array over a wide angle is demonstrated. The resulting ray trajectory through the waveguide is modeled using linear equations. Spot size growth is modeled using previously defined ray transfer matrices for tilted optical elements. The model is validated by comparison with experimental …
Fibre Bragg Grating Sensors For Acoustic Emission And Transmission Detection Applied To Robotic Nde In Structural Health Monitoring, Graham Wild, Steven Hinckley
Fibre Bragg Grating Sensors For Acoustic Emission And Transmission Detection Applied To Robotic Nde In Structural Health Monitoring, Graham Wild, Steven Hinckley
Research outputs pre 2011
Distributed acoustic emission sensors are used in structural health monitoring (SHM) for the detection of impacts and/or strain, in real time. Secondary damage may result from the initial impact or strain. This damage may include surface pitting, erosion, or cracking. This type of damage may not be detectable by the SHM system, specifically in passive fiber optic based sensing systems. The integration of non-destructive evaluation (NDE) by robots into SHM enables the detection and monitoring of a wider variety of damage. Communicating via acoustic transmissions represents a wireless communications method for use by NDE inspection robots to communicate with an …
Providing Qos For Symmetrical Voice/Video Traffic In Wireless Networks, Justin Wyatt, Daryoush Habibi, Iftekhar Ahmad, Hushairi Zen
Providing Qos For Symmetrical Voice/Video Traffic In Wireless Networks, Justin Wyatt, Daryoush Habibi, Iftekhar Ahmad, Hushairi Zen
Research outputs pre 2011
Voice over IP (VoIP) and voice-video over IP (VIoIP) are becoming very popular and widespread. These types of real-time services produce streams that are almost symmetrical in nature. A new token passing media access control (MAC) developed by our group, called wireless token network (WTN), has been designed with QoS guarantees in mind. We have previously shown in our previous paper (2006) that WTN supports a higher number of VoIP clients compared to 802.11e due to its higher channel efficiency. In this paper we show that WTN also provides superior QoS for bidirectional streams such as VIoIP due to a …
Rerouting Technique For Faster Restoration Of Preempted Calls, Iftekhar Ahmad, Joarder Kamruzzaman, Daryoush Habibi
Rerouting Technique For Faster Restoration Of Preempted Calls, Iftekhar Ahmad, Joarder Kamruzzaman, Daryoush Habibi
Research outputs pre 2011
In a communication network where resources are shared between instantaneous request (IR) and book-ahead (BA) connections, activation of future BA connections causes preemption of many on-going IR connections upon resource scarcity. A solution to this problem is to reroute the preempted calls via alternative feasible paths, which often does not ensure acceptably low disruption of service. In this paper, a new rerouting strategy is proposed that uses the destination node to initiate the rerouting and thereby reduces the rerouting time, which ultimately improves the service disruption time. Simulations on a widely used network topology suggest that the proposed rerouting scheme …
Minimizing The Number Of Constraints For Shared Backup Path Protection (Sbpp) In Shared Risk Link Group (Srlg) Optical Mesh Networks, Daryoush Habibi, Viet Quoc Phung, Hoang N. Nguyen
Minimizing The Number Of Constraints For Shared Backup Path Protection (Sbpp) In Shared Risk Link Group (Srlg) Optical Mesh Networks, Daryoush Habibi, Viet Quoc Phung, Hoang N. Nguyen
Research outputs pre 2011
Path-arc integer linear programming (ILP) models for shared backup path protection (SBPP) in optical mesh networks generally contain many redundant constraints for calculating shared backup capacity. This greatly increases the computational time of the ILP solvers. In this paper, we first identify the sharing relationship between working and backup capacities, which facilitates the development of two novel algorithms for minimizing the number of constraints in ILP models for SBPP in mesh networks. Next, we consider the more realistic case of Shared Risk Link Group (SRLG) networks, where some optical fibers have the same risk of a physical cut due to …