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Articles 2221 - 2250 of 2383

Full-Text Articles in Physical Sciences and Mathematics

High-Speed Electronic Speckle Pattern Interferometry, Carol Armstrong Jan 2004

High-Speed Electronic Speckle Pattern Interferometry, Carol Armstrong

Masters

Electronic Speckle Pattern Interferometry (ESPI) is used to measure surface displacements. Phase shifting can be used to obtain a fringe pattern which depicts the phase at every point in an image. Previous studies have used algorithms such as the 4-bucket algorithm to obtain phase maps of objects. After the object is displaced a second phase map is obtained in the same way and by correlation the phase difference due to the displacement can be determined. When the object is in rapid continuous motion these algorithms cannot be used. Towards this end a 5-frame algorithm was written, in which the calibrated …

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Studies In Cardiac Defribrillation, Eamonn Mckenna Jan 2004

Studies In Cardiac Defribrillation, Eamonn Mckenna

Masters

Cardiac disease resulting in cardiac arrest is one of the most common fatal diseases in the developed world. Defibrillation is the medical procedure used to correct the irregular cardiac rhythm (ventricular fibrillation (VF)) which is very often detected in patients suffering cardiac arrest. In the work reported in this thesis, two aspects of the defibrillation of patients in VF were examined. The first area of investigation concentrated on the use of multiple defibrillation electrodes to be used during closed chest (transthoracic) defibrillation. This study was carried out in a saline bath and centred on “focusing” electric fields from perimeter electrodes …

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Electronic Speckle Pattern Shearing Interferometer With A Photopolymer Holographyc Grating, Emilia Mihaylova, Izabela Naydenova, Suzanne Martin, Vincent Toal Jan 2004

Electronic Speckle Pattern Shearing Interferometer With A Photopolymer Holographyc Grating, Emilia Mihaylova, Izabela Naydenova, Suzanne Martin, Vincent Toal

Articles

A photopolymer holographic grating is used to produce the two sheared images in an electronic speckle pattern shearing interferometer. A ground glass screen following the grating serves the purpose of eliminating unwanted diffraction orders and to remove the requirement for the CCD camera to resolve the diffraction grating’s pitch. The sheared images on the ground glass are further imaged onto the CCD camera. The fringe pattern contrast was estimated to be above 90%. A validation of the system was done by comparing the theoretical phase difference distribution with the experimental data from the three point bending test.

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Objective Measurements Of Image Quality, Jacinta Browne, Amanda Watson, Nicholas Gibson, Nicholas Dudley, Alex Elliott Jan 2004

Objective Measurements Of Image Quality, Jacinta Browne, Amanda Watson, Nicholas Gibson, Nicholas Dudley, Alex Elliott

Articles

Tissue harmonic imaging (THI) and compound imaging have been reported clinically to improve contrast resolution, tissue differentiation and overall image quality. However, there have been limited studies to date to quantify objectively the improvements in image quality achieved with these new imaging techniques. The aim of this study was to quantify differences in image quality that exist between conventional B-mode imaging, harmonic imaging, compound imaging and harmonic compound imaging. An ATL HDI 5000 scanner with three probes (C5-2, L7-4 and L12-5) was tested with two different types of test object, the Gammex-RMI model 404 GS LE and the Gammex-RMI 403 …

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Non Linear Electronic And Optical Processes In Fullerene Thin Films, Siobhan Phelan Jan 2004

Non Linear Electronic And Optical Processes In Fullerene Thin Films, Siobhan Phelan

Masters

In this study the current voltage characteristics of C60 thin film sandwich structures fabricated by vacuum deposition on indium tin oxide (ITO) with an aluminium top electrode are presented and discussed. A strongly non-linear behaviour and a sharp increase in the device conductivity was observed at relatively low voltages, at both room and low temperatures (30K). At room temperature the system is seen to collapse. In situ Raman measurements indicate that the collapse is the result of a solid state reduction of the fullerene thin film to a polymeric state. The high conductivity state was seen to be stable at …

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Crash Analysis: An Investigation Of Current Speed Estimation Techniques, Robert Rice Jan 2004

Crash Analysis: An Investigation Of Current Speed Estimation Techniques, Robert Rice

Masters

The increasing number of cars and collisions on the roads of Europe ensure that the need for accurate speed estimation is an ever-more pressing requirement. This requirement has provided the motivation for an investigation into the accuracy and reliability of existing crash models An in-depth literature review was undertaken to create a greater understanding of the structural collapse behaviour of vehicles during full frontal collisions. It was decided to concentrate the work on frontal collisions as this type of accident makes up the majority of road accidents. This review underlined some of the phenomena that need to be considered when …

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An Analysis Of Case-Base Editing In A Spam Filtering Systems, Sarah Jane Delany, Padraig Cunningham Jan 2004

An Analysis Of Case-Base Editing In A Spam Filtering Systems, Sarah Jane Delany, Padraig Cunningham

Conference papers

Because of the changing nature of spam, a spam filtering system that uses machine learning will need to be dynamic. This suggests that a case-based (memory-based) approach may work well. Case-Based Reasoning (CBR) is a lazy approach to machine learning where induction is delayed to run time. This means that the case base can be updated continuously and new training data is immediately available to the induction process. In this paper we present a detailed description of such a system called ECUE and evaluate design decisions concerning the case representation. We compare its performance with an alternative system that uses …

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An Assessment Of Case Base Reasoning For Short Text Message Classification, Matt Healy, Sarah Jane Delany, Anton Zamolotskikh Jan 2004

An Assessment Of Case Base Reasoning For Short Text Message Classification, Matt Healy, Sarah Jane Delany, Anton Zamolotskikh

Conference papers

Message classification is a text classification task that has provoked much interest in machine learning. One aspect of message classification that presents a particular challenge is the classification of short text messages. This paper presents an assessment of applying a case based approach that was developed for long text messages (specifically spam filtering) to short text messages. The evaluation involves determining the most appropriate feature types and feature representation for short text messages and then comparing the performance of the case-based classifier with both a Naıve Bayes classifier and a Support Vector Machine. Our evaluation shows that short text messages …

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An Agent-Based Approach To Adaptive Navigational Support Within 3d-Environments, Bianca Schoen-Phelan, Gregory O'Hare, Brian Duffy, Alan Martin Jan 2004

An Agent-Based Approach To Adaptive Navigational Support Within 3d-Environments, Bianca Schoen-Phelan, Gregory O'Hare, Brian Duffy, Alan Martin

Conference papers

his paper investigates mechanisms and approaches to assisting user navigation and exploration within 3-dimensional worlds. Specifically it advocates the deployment of an agentbased approach to dynamic system assistance and intervention. A performance equation is presented in a basic and an extended version, which is used to activate system interventions and to evaluate user performances online and offline. The measure is derived via a light-weight computationally inexpensive masking approach. We describe some navigation experiments and the results of navigational intervention via the damping of the sensitivity of the navigational keys. Interestingly the navigational assistance does not yield improvements in the subjects’ …

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Openmvc: A Non-Proprietary Component-Based Framework For Web Applications, Ronan Barrett, Sarah Jane Delany Jan 2004

Openmvc: A Non-Proprietary Component-Based Framework For Web Applications, Ronan Barrett, Sarah Jane Delany

Conference papers

No abstract provided.

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Virtual Personal Assistants In A Pervasive Computing World, John F. Bradley, Brian R. Duffy, Gregory O'Hare, Alan Martin, Bianca Schoen-Phelan Jan 2004

Virtual Personal Assistants In A Pervasive Computing World, John F. Bradley, Brian R. Duffy, Gregory O'Hare, Alan Martin, Bianca Schoen-Phelan

Conference papers

Computing paradigms are constantly evolving-from mainframe to desktop, and on to ubiquitous computing. With a wide variety of devices, each with varying constraints, it would be quite difficult to develop services that would operate in a uniform manner across all platforms. With this in mind we offer an agent based solution. Agent attributes of autonomy, adaptability and mobility make them highly suitable for use in pervasive computing environments. Agent Chameleons illustrates a framework for Virtual Personal Assistants (VPA) for the information age. This paper briefly outlines some of the technologies and concepts that underpin the functionality of a VPA.

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An Investigation Of The Relationship Between In-Vitro And In-Vivo Ultrasound Image Quality Parameters, Jacinta Browne, Amanda Watson, Cathy Muir, Peter Hoskins, Alex Elliott Jan 2004

An Investigation Of The Relationship Between In-Vitro And In-Vivo Ultrasound Image Quality Parameters, Jacinta Browne, Amanda Watson, Cathy Muir, Peter Hoskins, Alex Elliott

Articles

The aim of this paper is to investigate the relationship between Bmode and colour Doppler technical test methods with the clinical perception of Bmode and Doppler invivo test parameters. It was found that technical and clinical comparisons between the Bmode test parameters: lateral resolution versus clinical resolution; anechoic target detection versus clinical noise; and penetration depth versus clinically useful penetration depth, demonstrated moderate correlations, (r= 0.69, p

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Validation Of A Sensitivity Performance Index Test Protocol And Evaluation Of Colour Doppler Sensitivity For A Range Of Ultrasound Scanners, Jacinta Browne, Amanda Watson, Peter Hoskins, Alex Elliott Jan 2004

Validation Of A Sensitivity Performance Index Test Protocol And Evaluation Of Colour Doppler Sensitivity For A Range Of Ultrasound Scanners, Jacinta Browne, Amanda Watson, Peter Hoskins, Alex Elliott

Articles

The ability to detect flow is the most crucial aspect of an ultrasound (US) system because, if flow cannot be detected, no other aspect of performance matters. The objectives of this study were to validate a Doppler “sensitivity performance index,” a figure of merit, and to determine if it could be used to differentiate colour Doppler sensitivity performance in scanners of varying complexity. The sensitivity performance index was developed to give a combined measure of related aspects of sensitivity, such as the lowest detectable velocity, the vessel size and the penetration depth. The colour Doppler sensitivity was evaluated objectively as …

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A Novel Tiq2-Assisted Solar Photocatalytic Batch-Process Disinfection Reactor For The Treatment Of Biological And Chemical Contaminants In Domestic Drinking Water In Developing Countries, E. F. Duffy, F. Al Touati, S. C. Kehoe, O. A. Mcloughlin, L. W. Gill, W. Gernjak, I. Oller, M. I. Maldonado, S. Malato, John Cassidy, R. H. Reed, K. G. Mcguigan Jan 2004

A Novel Tiq2-Assisted Solar Photocatalytic Batch-Process Disinfection Reactor For The Treatment Of Biological And Chemical Contaminants In Domestic Drinking Water In Developing Countries, E. F. Duffy, F. Al Touati, S. C. Kehoe, O. A. Mcloughlin, L. W. Gill, W. Gernjak, I. Oller, M. I. Maldonado, S. Malato, John Cassidy, R. H. Reed, K. G. Mcguigan

Articles

he technical feasibility and performance of photocatalytic Ti02 coatings in batch-process solar disinfection (SODIS) reactors to improve potability of drinking water in developing countries have been studied. Borosilicate glass and PET plastic SODIS reactors fitted with flexible plastic inserts coated with Ti02 powder were shown to be 2(Jt1o and 25% more effective, respectively, than standard SODIS reactors for the inactivation of E. coli K12. Isopropanol at 100 ppm concentration levels was observed to be completely photodegraded after 24 h continuous exposure to lOG mW/cm2 simulated sunlight in a similar solar photocatalytic disinfector (SPC-DIS) reactor. The technique for p roducing the …

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Increased Frequency Of The Mthfr A1298c Mutation In An Irish Population, Cathal Mccarthy, Fergus Ryan, Joseph Vaughan Jan 2004

Increased Frequency Of The Mthfr A1298c Mutation In An Irish Population, Cathal Mccarthy, Fergus Ryan, Joseph Vaughan

Articles

No abstract provided.

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Modelling Growth And Testing Of Multilayer Cavity Structures Incorporating Birefringent Materials, Nour-Eddine El Khachia Dec 2003

Modelling Growth And Testing Of Multilayer Cavity Structures Incorporating Birefringent Materials, Nour-Eddine El Khachia

Masters

A simple one-dimensional photonic bandgap structure, which is also known as a Fabry-Perot Microcavity (FPM) structure was studied theoretically and experimentally. In particular this project addressed introducing an optically birefringent material in the cavity. This FPM consists of two grown regular Distributed Bragg Reflector (DBR) mirrors that can be put together as a sandwich with a space between them, which will lead to the creation of the desired cavity. Each mirror, or one-dimensional dielectric stack structure, was grown using the Vacuum Evaporation Technique and consists of multiple layers of alternating high-and low-refractive index dielectric materials arranged periodically. The project covers …

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Viewer-Based Directional Querying For Mobile Applications, Keith Gardiner, James Carswell Dec 2003

Viewer-Based Directional Querying For Mobile Applications, Keith Gardiner, James Carswell

Conference papers

With the steady and fast advancements in the integration of geographic information systems and mobile location-based services, interest in exploiting this technology for Cultural Heritage (CH) data sharing has become apparent. In this area there has been an increasing need to integrate positional information with non-positional data and add a spatial dimension to the definition of a users “context”. In this paper we describe an implementation of a viewer-based directional query processor that operates on an Oracle Spatial database. The spatial position and orientation are taken from the viewer’s perspective. Using this frame of reference a view-port is defined in …

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Spatial Frequency Response Of Acrylamide Based Holographic Photopolymer, Raghavendra Jallapuram, Izabela Naydenova, Vincent Toal, Suzanne Martin, Robert Howard Dec 2003

Spatial Frequency Response Of Acrylamide Based Holographic Photopolymer, Raghavendra Jallapuram, Izabela Naydenova, Vincent Toal, Suzanne Martin, Robert Howard

Conference Papers

It has been shown that photopolymers are useful in holographic optical elements [1] and holographic interferometry [2]. However, the list of potential applications increases greatly if reflection holography is possible. Reflection holography requires a material that has the potential to record high spatial frequencies. Here we studied the spatial frequency response of an acrylamide based dye sensitized holographic photopolymer. We have investigated the effect of molecular weight of the binder and concentration of crosslinking monomer on diffusion using real time monitoring of the holographic grating formation. The effect of uniform pre-exposure on diffusion was also investigated. We have also demonstrated …

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Ecotoxicological Research At Dit, Maria Davoren, Colm O'Dowd, Sharon Ni Shuilleabhain Nov 2003

Ecotoxicological Research At Dit, Maria Davoren, Colm O'Dowd, Sharon Ni Shuilleabhain

Articles

The term ecotoxicology first defined by Rene Truhart in 1969, essentially describes the study of the harmful effects of chemicals upon ecosystems.

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Microtonal Systems And Guitar Composition, Michael Nielsen Oct 2003

Microtonal Systems And Guitar Composition, Michael Nielsen

Masters

This thesis focuses on the use of microtones in guitar composition. In the course of this study the physical aspects of musical sound (pitch, loudness and quality/timbre), vibrational frequencies of strings, and the theory of musical scales and tuning systems are discussed. Whole-number ratios corresponding to musical intervals within the twelve-note/equal temperament scale are calculated in relation to the overtone series for the purpose of surveying consonance and dissonance within the tempered system. These are compared to the ratios for corresponding intervals within the overtone series. Whole-number ratios are also calculated for intervals involving the microtones referred to in this …

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Transition Probabilities In Kr Ii And Kr Iii Spectra, Stevan Djenize, Vladimir Milosavljevic, Milan S. Dimitrijevic Sep 2003

Transition Probabilities In Kr Ii And Kr Iii Spectra, Stevan Djenize, Vladimir Milosavljevic, Milan S. Dimitrijevic

Articles

On the basis of the relative line intensity ratio (RLIR) method, transition probability values of the spontaneous emission (Einstein's A values) of 14 transitions in the singly (Kr II) and 7 transitions in doubly (Kr III) ionized krypton spectra have been obtained relatively to the reference A values related to the 435.548 nm Kr II and 324.569 nm Kr III, the most intensive transitions in the Kr II and Kr III spectra. Our Kr III transition probability values are the first data obtained experimentally using the RLIR method. A linear, low–pressure, pulsed arc operated in krypton discharge was used as …

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Growth Of Well-Defined Zno Microparticles By Hydroxide Ion, Ruth Mcbride, Declan Mccormack, John Kelly Aug 2003

Growth Of Well-Defined Zno Microparticles By Hydroxide Ion, Ruth Mcbride, Declan Mccormack, John Kelly

Articles

The morphology of the microcrystalline zinc oxide formed by reaction of zinc salts with sodium hydroxide depends critically on the reaction conditions. To understand this, the nature of the solid product has been probed by scanning electron microcopy (SEM) and X-ray diffraction (XRD) and the concentration of zinc remaining in the solution has been determined at regular intervals throughout the reaction. Two general preparative procedures have been followed. The first, which involves simply heating an aqueous solution containing Zn(NO3)2 (0.025 M) and sodium hydroxide (0.375 M) to 101 uC and maintaining it at that temperature for periods of up to …

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Astrophysical Plasma Diagnostics Through Analysis Of Ar Iine Shape Characteristics, Vladimir Milosavljevic, Stevan Djenize Jul 2003

Astrophysical Plasma Diagnostics Through Analysis Of Ar Iine Shape Characteristics, Vladimir Milosavljevic, Stevan Djenize

Articles

On the basis of five accurately recorded neutral argon ( ) line shapes (in the 4s-5p transition) we have recovered the basic plasma parameters i.e. electron temperature ( T) and electron density ( N) using our new line deconvolution procedure in the case of three different plasmas created in a linear, low-pressure, pulsed arc discharge. The mentioned plasma parameters have also been measured using independent experimental diagnostic techniques. An excellent agreement has been found among the two sets of obtained parameters. This recommends our deconvolution procedure for plasma diagnostic purposes, especially in astrophysics where direct measurements of the …

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Experimental And Calculated Stark Widths Within The Kr I Spectrum, Vladimir Milosavljevic, Stevan Djenize, Milan S. Dimitrijevic Jul 2003

Experimental And Calculated Stark Widths Within The Kr I Spectrum, Vladimir Milosavljevic, Stevan Djenize, Milan S. Dimitrijevic

Articles

On the basis of the precisely recorded 20 neutral krypton (Kr I) line shapes (in the 5s−5p and 5s−6p transitions), we have obtained the basic plasma parameters, i.e., electron temperature (T) and electron density (N) using our line deconvolution procedure in a plasma created in a linear, low-pressure, pulsed arc discharge operated in krypton. The mentioned plasma parameters have also been measured using independent experimental diagnostics techniques. Agreement has been found among the two sets of the obtained parameters. This recommends our deconvolution procedure for plasma diagnostical purposes, especially in astrophysics where direct measurements of the …

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Application Of A Photopolymer Material In Speckle Pattern Shearing Interferometry, Emilia Mihaylova, Izabela Naydenova, Suzanne Martin, Vincent Toal Jun 2003

Application Of A Photopolymer Material In Speckle Pattern Shearing Interferometry, Emilia Mihaylova, Izabela Naydenova, Suzanne Martin, Vincent Toal

Conference Papers

A new application of a photopolymer diffractive optical element in electronic speckle pattern shearing interferometer (ESPSI) is presented. In the first stage a holographic grating is recorded using an acrylamide based photopolymer material. Since the polymerisation process occurs during recording, the holograms are produced without any development or processing. In the second stage the holographic grating is used to produce the two sheared images in an ESPSI configuration. A ground glass screen following the grating serves the purpose of eliminating unwanted diffraction orders. The distance between the grating and the ground glass can be used to control the amount of …

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Microspectrophotometry Of Respiratory Pigments, Karen Yvonne Kavanagh Jun 2003

Microspectrophotometry Of Respiratory Pigments, Karen Yvonne Kavanagh

Doctoral

This research thesis describes the design, construction and optical testing of three fibre-optic microspectrophotometer systems to monitor the reduction of mitochondrial respiratory pigments. The optical and biochemical characteristics of mitochondrial respiration are discussed and the current optical techniques employed in the biochemical analysis of respiratory enzymes are presented. The primary focus of this study is the system parameters surrounding the spectrophotometric determination of mitochondrial respiratory activity. Three separate fibre-optic set-ups are described, which use visible spectrophotometry to measure the reduction of mitochondrial electron carriers from a range of biological sources. Each system is based around the Ocean Optics S1000/S2000 series …

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Reply To "Comment On ‘Atomic Spectral Line Free-Parameter Deconvolution Procedure’”, Vladimir Milosavljevic, Goran Poparic May 2003

Reply To "Comment On ‘Atomic Spectral Line Free-Parameter Deconvolution Procedure’”, Vladimir Milosavljevic, Goran Poparic

Articles

We do not agree with the authors of the preceding Comment [X. Nikolic, X. Ojurovic, and X. Mijatovic, Phys. Rev. E, 67, 058401, 2003]. Our numerical procedure for the deconvolution of the theoretical asymmetric convolution integral of a Gaussian and a plasma broadened spectral line profile jA,R(λ) for spectral lines enables the determination of all broadening parameters. All broadening parameters can be determined directly from the recorded line profile of a single line, with minimal assumptions or prior knowledge. Additional experimental diagnostics are not required.

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Characterisation Of Polymer-Modified Electrodes, Karl Crowley May 2003

Characterisation Of Polymer-Modified Electrodes, Karl Crowley

Doctoral

In this work, two contrasting polymer-modified electrodes are investigated. Electroanalysis of lead in aqueous solutions was performed with an electrode coated with Nafion and the redox behaviour of the electronically conducting polymer, polypyrrole, was characterised. In the first study, a glassy carbon electrode coated with Nafion was used in the determination of lead through anodic stripping voltammetry (ASV). Initially the work consisted of optimising the preparation of the electrode and the experimental conditions resulting in a reproducible Nafion-modified electrode (NME) with a lifetime of several weeks. Two different stripping techniques were examined. High frequency square wave ASV was found to …

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The He I 706.52 Nm Line Shape Characteristics In The Plasma Diagnostics, Vladimir Milosavljevic, Stevan Djenize Apr 2003

The He I 706.52 Nm Line Shape Characteristics In The Plasma Diagnostics, Vladimir Milosavljevic, Stevan Djenize

Articles

On the basis of the precisely recorded 706.52 nm He I line shape we have obtained the basic plasma parameters i.e. electron temperature (T) and electron density (N) using our new line deconvolution procedure in the case of five various plasmas created in a linear, low–pressure, pulsed arc discharge. Plasma parameters have been also measured using independent experimental diagnostical techniques. Excellent agreement was found among the two sets of the obtained parameters. This enables our deconvolution procedure to recommendation for plasma diagnostical purposes, especially in astrophysics where direct measurements of the plasma parameters (T and …

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On-Line Spatial Processing Systems, James Carswell, Michela Bertolotto Apr 2003

On-Line Spatial Processing Systems, James Carswell, Michela Bertolotto

Articles

On-line Spatial Processing (OLSP) delivers high performance spatial systems for the modelling and monitoring of dynamic environments. It provides an ideal solution for the management of networks, land and assets, and the real-time tracking of changing spatial systems. OLSP is server-centric, as opposed to the primarily desktop-centric world of GIS. It places spatial data at the heart of the organisation's IT systems and integrates it with business and attribute data. The result is more effective use of spatial data and improved decision support and spatial intelligence throughout the organisation.

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