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Articles 1 - 14 of 14
Full-Text Articles in Engineering
Optimisation Of Multicast Routing In Wireless Mesh Networks, Brian Keegan, Karol Kowalik, Mark Davis
Optimisation Of Multicast Routing In Wireless Mesh Networks, Brian Keegan, Karol Kowalik, Mark Davis
Conference papers
In recent years Wireless Mesh Networks have been deployed and grown in popularity in many metropolitan areas. The deployment of such networks has allowed clients to gain access to publicly available broadband networks. The implementation of wireless mesh networks requires that backhaul services (traditionally carried by wired networks) be maintained via wireless mesh points. Because of their structure, wireless mesh networks provide an excellent means for targeting a large group of end users or simply to relay data. This may be achieved by means of broadcasting or more specifically multicasting. The lack of standards and support for multicasting over wireless …
Investigation Of Across-Layer Modification To The Dsr Routing Protocol In Wireless Mesh Networks, Mustafa Ramadhan, Mark Davis
Investigation Of Across-Layer Modification To The Dsr Routing Protocol In Wireless Mesh Networks, Mustafa Ramadhan, Mark Davis
Conference papers
This work introduces a cross-layer modification to the DSR protocol that increases the global throughput in wireless mesh networks. In our modified DSR protocol we have introduced the Access Efficiency metric as an alternative to the hop-count metric in order to improve the route selection mechanism. The selected path in the route selection mechanism is identified by choosing the path with the highest minimum Access Efficiency value. We have employed the OPNET modeller as a simulator to examine two different patterns of traffic for a series of randomly generated network topologies. Each topology was simulated twice. One simulation used the …
Effects Of Lline Rate On Vvideo Qos Over Wireless Networks: An Experimental Approach, Stuart Wallace, Mark Davis
Effects Of Lline Rate On Vvideo Qos Over Wireless Networks: An Experimental Approach, Stuart Wallace, Mark Davis
Conference papers
Video streaming over Wireless Local Area Networks (WLANS) is becoming an increasingly popular service. However, end user OoS is highly influenced by many factors. These include the video codec used, the packetization scheme, error concealment and correction techniques, the complexity of the video, propagation losses, and the line rate. In this paper the effect of the line rate on the capacity of the network when streaming multimedia content is analyzed experimentally. It is shown that as the line rate decreases the bandwidth load of the video stream dramatically increases leading to poor QoS at the client side. As automatic line …
An Investigation Of The Correlation Between Passive Monitoring And Activie Probing Techniques Used In Wlan Mesh Networks, Chenzhe Zhang, Mark Davis
An Investigation Of The Correlation Between Passive Monitoring And Activie Probing Techniques Used In Wlan Mesh Networks, Chenzhe Zhang, Mark Davis
Conference papers
In recent years, Wireless Mesh Networks (WMNs) have emerged as a promising solution to provide low cost networks that extend Internet access and other networking services. Mesh routers form the backbone connectivity through cooperative routing in an often unstable wireless medium. Therefore, the techniques used to monitor and manage the performance metrics to help optimize the link performance in WMNs. This paper presents an assessment of the correlation between passive monitoring and active probing techniques used for link performance measurement in WMNs. This paper presents an assessment of the correlation between passive monitoring and active probing techniques used for link …
Hand-Held Flyback Driven Coaxial Dielectric Barrier Discharge: Development And Characterization, Victor J. Law, Vladimir Milosavljevic, Neil O’Connor, James F. Lalor, Steven Daniels
Hand-Held Flyback Driven Coaxial Dielectric Barrier Discharge: Development And Characterization, Victor J. Law, Vladimir Milosavljevic, Neil O’Connor, James F. Lalor, Steven Daniels
Articles
The development of a handheld single and triple chamber atmospheric pressure coaxial dielectric barrier discharge driven by Flyback circuitry for helium and argon discharges is described. The Flyback uses external metal-oxide-semiconductor field-effect transistor power switching technology and the transformer operates in the continuous current mode to convert a continuous dc power of 10–33 W to generate a 1.2–1.6 kV 3.5 μs pulse. An argon discharge breakdown voltage of ∼768 V is measured. With a 50 kHz, pulse repetition rate and an argon flow rate of 0.5–10 argon slm (slm denotes standard liters per minute), the electrical power density deposited in …
Control Of Double Fed Induction Generator Wind Turbine During Network Voltage Unbalance Conditions, Joseph Kearney, Michael Conlon
Control Of Double Fed Induction Generator Wind Turbine During Network Voltage Unbalance Conditions, Joseph Kearney, Michael Conlon
Conference papers
The behaviour of Double-Fed Induction Generators to supply network voltage unbalance is investigated. The paper describes a method to control the rotor-side converter in a DFIG when subjected to the effects of network voltage unbalance conditions. A parallel control scheme is implemented to control the positive and negative sequence components independently. A DFIG model is implemented in Matlab/Simulink and simulations show the reduction in power and torque oscillations and a reduction in the high unbalanced currents generated as a result of the applied voltage unbalance.
An Evaluation Of A Conservative Transmit Power Control Mechanism On An Indoor 802.11 Wireless Mesh Testbed, Karol Kowalik, Marek Bykowski, Brian Keegan, Mark Davis
An Evaluation Of A Conservative Transmit Power Control Mechanism On An Indoor 802.11 Wireless Mesh Testbed, Karol Kowalik, Marek Bykowski, Brian Keegan, Mark Davis
Conference papers
Power control techniques for IEEE 802.11 wireless networks have already gained considerable attention. Such techniques are particularly attractive because they can improve various aspects of wireless network operation such as interference mitigation, spatial reuse in dense wireless deployments, topology control, and link quality enhancement. In this paper we propose a novel delivery ration based Conservative Transmit Power Control (ConTPC) mechanism. Our implementation is conservative when it comes to deciding if the transmit power should be reduced for a given link. This is because we do not want poor quality wireless links to further reduce their quality and be overwhelmed by …
Practical Issues Of Power Control In Ieee 802.11 Wireless Devices, Karol Kowalik, Marek Bykowski, Brian Keegan, Mark Davis
Practical Issues Of Power Control In Ieee 802.11 Wireless Devices, Karol Kowalik, Marek Bykowski, Brian Keegan, Mark Davis
Conference papers
Power control techniques for IEEE 802.11 wireless networks have already gained much attention. Such techniques are particularly attractive because they can improve various aspects of wireless network operations such as interference mitigation, spatial reuse in dense wireless deployments, topology control, and link quality enhancement. However, until recently implementing such advanced power control using off-the-shelf wireless devices was not considered possible. For example, Abdesslem et al. [1] stated that “many novel power control solutions cannot be efficiently implemented over existing IEEE 802.11 cards”. However, in this paper we demonstrate that power control is now feasible and can be implemented in current …
Real-Time Plasma Controlled Chemistry In A Two-Frequency, Confined Plasma Etcher, Vladimir Milosavljevic, Albert R. Ellingboe, Cezar Gaman, John V. Ringwood
Real-Time Plasma Controlled Chemistry In A Two-Frequency, Confined Plasma Etcher, Vladimir Milosavljevic, Albert R. Ellingboe, Cezar Gaman, John V. Ringwood
Articles
The physics issues of developing model-based control of plasma etching are presented. A novel methodology for incorporating real-time model-based control of plasma processing systems is developed. The methodology is developed for control of two dependent variables (ion flux and chemical densities) by two independent controls (27 MHz power and O2flow). A phenomenological physics model of the nonlinear coupling between the independent controls and the dependent variables of the plasma is presented. By using a design of experiment, the functional dependencies of the response surface are determined. In conjunction with the physical model, the dependencies are used to deconvolve the sensor …
Throughput Enhancement Through Combined Fragmentation And Rate Method In Ieee 802.11b Wlans, Marek Bykowski, Karol Kowalik, Brian Keegan, Mark Davis
Throughput Enhancement Through Combined Fragmentation And Rate Method In Ieee 802.11b Wlans, Marek Bykowski, Karol Kowalik, Brian Keegan, Mark Davis
Conference papers
IEEE 802.11 allows for fragmentation tuning and rate selection. Their combined usage is referred sometimes to link adaptation. However, the algorithms of link adaptation are beyond the 802.11 standards. In this paper we investigate the benefits arising from proper use of link adaptation. Particularly, we develop a mathematical model describing the fragmented transmission in 802.11b. We examine potential benefits of it over AWGN and fading channels. More significantly we combine fragmentation tuning with bit-rate selection to yield the highest achievable throughput performance for any given channel conditions. Finally, we propose an algorithm that performs the optimal link adaptation.
Teaching And Assessment Of Students Taking A First Year, Level 7 Subject: Analysis And Actions, Aidan O'Dwyer
Teaching And Assessment Of Students Taking A First Year, Level 7 Subject: Analysis And Actions, Aidan O'Dwyer
Conference papers
This contribution critically analyses the teaching and assessment strategies used on the core Electrical Systems subject in the first year of a three-year, Level 7, degree programme in Electrical Engineering at Dublin Institute of Technology. The author has the responsibility for development and instruction in the subject since 2004. In the 2004-5 and 2005-6 academic years, the didactic teaching approach and the assessment strategy ensured good educational outcomes. This was not the case in the 2006-7 academic year. The contribution will analyse the reasons for this, taking an evidence-based approach (i.e. analysing the assessment data in detail). Two conclusions that …
A Mobile Ecg Monitoring System With Context Collection, Jin Peng Li
A Mobile Ecg Monitoring System With Context Collection, Jin Peng Li
Masters
An objective of a health process is one where patients can stay healthy with the support of expert medical advice when they need it, at any location and any time. An associated aim would be the development of a system which places increased emphasis on preventative measures as a first point of contact with the patient. This research is a step along the road towards this type of preventative healthcare for cardiac patients. It seeks to develop a smart mobile ECG monitoring system that requests and records context information about what is happening around the subject when an arrhythmia event …
Antennas For Portable Communications In The Uwb And Gps Spectra., Giuseppe Ruvio
Antennas For Portable Communications In The Uwb And Gps Spectra., Giuseppe Ruvio
Doctoral
The thesis describes a study of antennas for solutions in emerging systems. An account of the fundamental principles of these antennas is given together with an outline of the basic electromagnetic theory on which the designs are based. While the main focus is on antennas for Ultra Wideband (UWB) systems, some additional work was carried out on enhancing performance of circularly polarised antennas for satellite navigation systems. The study focussed on the design of highly efficient broadband antennas with particular requirements for size compactness, gain stability, phase-linearity, and the use of low-cost materials. These requirements are particularly important for UWB …
Drop Photometer Design., Kevin Tiernan
Drop Photometer Design., Kevin Tiernan
Doctoral
The tensiograph drop analyser, operating in the mode of ultraviolet-visual absorption photometer, was re-engineered to improve measurement accuracy. As well as instrumentation re-design, the other objective of the research was to analyse tensiograph signals to explore how their features are defined by drop properties. Using fibre optic technology, the tensiograph emits a light beam into a growing pendant drop whereupon it undergoes a number of internal reflections. A portion of the reflected light energy is coupled to a photodiode producing a proportional current that is electronically processed and transferred to a computer for analysis. The signal produced, known as the …