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Technological University Dublin

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Articles 271 - 278 of 278

Full-Text Articles in Electrical and Electronics

A Wireless Traffic Probe For Radio Resource Management And Qos Provisioning In Ieee 802.11 Wlans, Mark Davis Jan 2004

A Wireless Traffic Probe For Radio Resource Management And Qos Provisioning In Ieee 802.11 Wlans, Mark Davis

Conference papers

The emergence of real-time services such as voice over IP (VoIP) and video streaming imposes stringent requirements on the performance of a network if quality of service (QoS) targets are to be achieved. In the case of wireless networks, some form of radio resource management (RRM) is typically required to allocate the available resources among the contending stations in accordance with their needs and respective priorities. A critical aspect of any RRM scheme is the ability to monitor resource usage and to determine the resource requirements on a per-station basis. In this paper we describe a wireless traffic probe for …


The Estimation And Control Of A Laboratory Heating And Ventilation System, Robin P. Mooney Sep 2003

The Estimation And Control Of A Laboratory Heating And Ventilation System, Robin P. Mooney

Masters in Advanced Engineering

This dissertation is concerned with the estimation and control of a laboratory heating and ventilation system (Instrutek VVS-400). The system is a 2x2 multi-input multi-output process (MIMO). It has been shown that simple techniques such as the ultimate cycle method do not provide adequate control of the process. The system was interfaced with a PC using Matlab/Simulink via a data acquisition package (Humusoft). Continuous time process identification techniques were applied to the flow and temperature processes. The alternative tangent and point method was used to model the processes, and their interaction, using a first order lag plus delay model. Models …


Study Of Structure And Quality Of Different Silicon Oxides Using Ftir And Raman Microscopy, C. Moore, T. S. Perova, B. Kennedy, Kevin Berwick, I. I. Shaganov, R. A. Moore Jan 2003

Study Of Structure And Quality Of Different Silicon Oxides Using Ftir And Raman Microscopy, C. Moore, T. S. Perova, B. Kennedy, Kevin Berwick, I. I. Shaganov, R. A. Moore

Articles

In this work, SiO2 and fluorine and phosphorous doped SiO2 thin films are investigated using FTIR and Raman techniques. FTIR spectroscopy was performed at normal and oblique incidence of the probe beam in transmission and reflection modes. The effect of polarisation and angle of incidence of the probe beam is examined for the case of reflection mode. Infrared spectra taken from doped oxides show that the structure changes with the passage of time. Alternate methods to calculate the thickness of the doped film are therefore discussed. Infrared spectra of electron beam evaporated oxides give valuable information on their …


Design Criteria And Optical Characteristics Of One-Dimensional Photonic Crystals Based On Periodically Grooved Silicon, Vladimir Tolmachev, Tatiana Perova, Kevin Berwick Jan 2003

Design Criteria And Optical Characteristics Of One-Dimensional Photonic Crystals Based On Periodically Grooved Silicon, Vladimir Tolmachev, Tatiana Perova, Kevin Berwick

Articles

Photonic bandgap (PBG) regions have been calculated for periodically grooved Si structures, acting as a one-dimensional photonic crystal. The wavelength range of the PBG as a function of the ratio (DSi/A) is presented, where DSi is the width of the Si walls and A is the grooved silicon lattice constant. The influence of the parameter DSi, the refractive index of the space between the Si walls and the number of structure periods, m, on the forming of PBG regions is discussed. A good correlation between the calculated and the experimentally observed …


Precise Chemical Analysis Development For Si And Gaas Surfaces, T. A. Briantseva, Z. M. Lebedeva, D. V. Lioubtchenko, M. Nolan, T. S. Perova, R. A. Moore, Kevin Berwick Jan 2002

Precise Chemical Analysis Development For Si And Gaas Surfaces, T. A. Briantseva, Z. M. Lebedeva, D. V. Lioubtchenko, M. Nolan, T. S. Perova, R. A. Moore, Kevin Berwick

Articles

Precise chemical analysis (PCA) was developed to allow the study of non-interconnected atoms on crystalline semiconductor surfaces, such as those produced during rapid thermal processing (RTP) of silicon and electron beam lithography on gallium arsenide (GaAs). The PCA method is based on selectively dissolving the different components present on the semiconductor surface using preferential etchant solutions. After etching, the etchant solution, containing the etched component, is analyzed by a photometric technique. In this paper, we present photometric measurements of the amount of “free” (non-interconnected) atoms that remain on semiconductor surfaces following electron beam and RTP processing. In this context, “free” …


Micro-Raman Study Of Stress Distribution Generated In Silicon During Proximity Rapid Thermal Diffusion, M. Nolan, T. Perova, R. A. Moore, C. J. Moore, Kevin Berwick, H. S. Gamble Jan 2000

Micro-Raman Study Of Stress Distribution Generated In Silicon During Proximity Rapid Thermal Diffusion, M. Nolan, T. Perova, R. A. Moore, C. J. Moore, Kevin Berwick, H. S. Gamble

Articles

proximity rapid thermal diffusion (RTD). A compressive stress was found on the whole silicon wafer after 15 s RTD. After 165 s RTD, the distribution of the stress across the wafer was found to be different: compressive at the edge and tensile at the middle. Thermal stress was relieved in the RTD wafers via slip dislocations. These slip dislocations were observed in the product wafers using optical microscopy. Slip lines propagated from the wafer edge to the wafer centre in eight preferred positions of maximum induced stress. The thermally induced stress and the slip dislocation density increased with time spent …


Structural Properties And Stress Analysis Of Sio2 Thin Films, G. Joyce, C. Moore, T. S. Perova, C. Beitia, A. Kocot, Kevin Berwick, Hugh Byrne, J. M. Mcgilp Jan 2000

Structural Properties And Stress Analysis Of Sio2 Thin Films, G. Joyce, C. Moore, T. S. Perova, C. Beitia, A. Kocot, Kevin Berwick, Hugh Byrne, J. M. Mcgilp

Conference papers

Wet and dry oxidations of (111) crystalline silicon wafers were performed at temperatures between 900°C and 1150°C and subsequently annealed at 700°C. Process parameters such as the withdrawal rate from the furnace and annealing time were varied and the effect on the oxide layer are discussed. The magnitude and nature of the stress in the wafers after thermal oxidation was analysed using micro-Raman spectroscopy. The Full Width at Half Maximum (FWHM) of the Raman peak at ~ 520 cm-1 was also analysed to extract information relating to crystal disorder and defect density caused by the oxidation process. The results obtained …


Fast Discharges In Thin Liquid Layers, Charles J. Frei, Aidan O'Dwyer Jan 1986

Fast Discharges In Thin Liquid Layers, Charles J. Frei, Aidan O'Dwyer

Conference papers

Several mechanisms can be at work when electrical discharges occur across a thin layer of an insulating liquid. The evidence is derived from the time-lag distributions of series of consecutive discharges when the measurements are performed with a sequence of constant voltage pulses.