• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 171
  • 51
  • 35
  • 26
  • 25
  • 14
  • 10
  • 7
  • 4
  • 4
  • 4
  • 3
  • 2
  • 1
  • 1
  • Tagged with
  • 420
  • 56
  • 55
  • 54
  • 46
  • 46
  • 36
  • 34
  • 34
  • 33
  • 32
  • 32
  • 32
  • 28
  • 26
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
251

"Jag behövde den där pushen från artrosskolan" : En kvalitativ intervjustudie om artrosskolans betydelse för motivation för patienter med knäartros

Hansson Löjdqvist, Julia, Dahlin, Sara January 2022 (has links)
SAMMANFATTNING Bakgrund: Artros är den vanligaste, kroniska ledsjukdomen som drabbar kroppens olika leder bland annat knäleden. Fysisk aktivitet är den främsta behandlingen vid ledsjukdomen där artrosskolan finns till som stöd för patienterna. Fysioterapeuterna i artrosskolan arbetar hälsofrämjande med artrospatienter genom att befrämja fysisk aktivitet. Syfte: Att undersöka vad patienter med knäartros upplever har påverkat deras motivation för fysisk aktivitet under artrosskolan. Metod: Denna studie är en kvalitativ intervjustudie som genomfördes med en induktiv ansats. Sex deltagare inkluderades i studien där en semistrukturerad intervjuguide användes. Vidare analyserades intervjuerna med en kvalitativ innehållsanalys. Materialet tolkades och sorterades i kategorier och underkategorier. Resultat: Studien resulterade i fem huvudkategorier som vidare delades in i sex underkategorier. Huvudkategorierna var: det sociala stödet på artrosskolan, enkel och lättillgänglig träning, ökad förståelse, upplevda effekter av artrosskolan och brist på uppföljning och personlig kontakt. Slutsatser: Resultatet indikerar att kompetens, självbestämmande och tillhörighet har haft en inverkan för vad som har påverkat motivationen för fysisk aktivitet. Deltagarnas upplevelser om vad som påverkat deras motivation kan därmed kopplas till Self-determination theory där tidigare nämna begrepp är tre viktiga grundstenar. Det har framgått att deltagarna upplevt att det sociala stödet från artrosskolan, fysiska och psykologiska effekter samt en ökad förståelse för artros och träningens betydelse har bidragit till ökad motivation för fysisk aktivitet.
252

Entwicklung und Test eines Hochtemperatur-Sensorsystems für den Einsatz an Turbomaschinen

Düsterhaupt, Stephan, Hoffmann, Hagen, Neumann, Holger, Noack, Ivo, Rottenbach, Torsten, Worlitz, Frank 20 October 2023 (has links)
Hochtemperaturmagnetlager in Turbomaschinen erfordern Lagesensoren, die den Umgebungsbedingungen ebenfalls dauerhaft standhalten und den Lagereglern hinreichend genaue und störungsfreie Informationen über die Rotorpositionen kontinuierlich zur Verfügung stellen. Ausgehend von den Einsatzbedingungen wurden mögliche Messprinzipien untersucht. In einem zweiten Schritt erfolgte die Recherche zu temperaturbeständigen Werkstoffen für die Sensorkomponenten und auf Basis einer Marktanalyse wurde deren Verfügbarkeit geprüft. Im Anschluss wurde ein kombinierter induktiver Radial-Axial-Lagesensor als Prototyp für den Einsatz am Magnet- und Fanglagerprüfstand MFLP ausgelegt. Dazu wurde ein analytischer Auslegungsalgorithmus für schnelle Auslegungsrechnungen erstellt und in MATLAB umgesetzt. Aufbauend auf den Ergebnissen der Auslegung wurde der Sensor konstruiert und gefertigt. Parallel dazu wurde eine Sensorelektronik entwickelt. Das Paper beschreibt die Auslegung und Konstruktion des Sensors und die Entwicklung der dazugehörigen Elektronik. / High-temperature magnetic bearings in turbomachinery require position sensors that can also withstand the ambient conditions permanently. This measurement system continuously provide the position controllers with sufficiently accurate and interference-free information about the rotor positions. Based on the operating conditions, suitable measurement principles were investigated. Furthermore suitable temperature-resistant materials for the sensor components were identified and their availability was checked based on a market analysis. Subsequently, a combined inductive radial-axial position sensor was developed. The demonstrator was designed for air gap measurements at the MFLP - a test rig for magnetic and backup bearings. For this purpose, an analytical design algorithm for fast design calculations was created and implemented in MATLAB. Based on the design results, the sensor was designed and manufactured. In parallel, sensor electronics were developed. The paper describes the design and construction of the sensor and the development of the associated electronics.
253

"It's hard. I love it, and it's hard!": Homeschool Moms' Navigation of Academic and Non-Academic Life

Gina Sue Reynolds (17059506) 29 September 2023 (has links)
<p dir="ltr">The concept of homeschooling in the United States, though more mainstream today, remains an alternative way of educating our children. Researchers seeking to examine this method of education often focus on the outcomes for the children who receive their education through this mode of education. Seldom does the attention fall to the educator, the homeschool parent. The mother typically takes the active role in educating the children and she receives little attention as a person (Lois, 2016). This study examines the ways in which these mother/teachers navigate the academic and non-academic parts of their lives and what impact that has on their own and their family’s well-being. Because the number of families who choose this mode of education continues to rise, examining factors that affect their well-being is crucial (Ray, 2022). Nine online discussions with 26 homeschooling mothers set up as focus groups revealed strong connections to self-efficacy and agency. Group sizes ranged from two to four participants making some of the groups dyadic interviews rather than focus groups (Morgan, 1996). Agency and self-efficacy contributed to the sense of well-being for the mother and by extension to her family (Bandura 1977, 2006). The findings from this study suggest other homeschool mothers and past experiences played a role in their self-efficacy that contributed to their well-being leading to their self-efficacy expectation. Though previous literature suggests that homeschooling mothers connect strongly to the concept of <i>good mother</i>, the mothers in this study rejected many of the principles Hays (1996) suggests a <i>good mother</i> exhibits. The use of metaphors as a qualitative tool aided in the discovery of ways these mothers navigate their lives and how their management impacted their families. As an engaged qualitative inductive study, suggestions to existing homeschool groups and organizations that hope to support homeschooling families gave a connection back to communities outside of academia.</p>
254

Development of a Testing Assembly for Powertrain Speed Sensors

Zafirakis, Zacharias January 2016 (has links)
Knowledge about the speed and the direction of the di˙erent shafts in the gearbox and the engine of trucks is becoming more and more important, especially as the industry moves towards autonomous vehicles. The most common way to measure these parame-ters today is by using inductive or Hall sensors. Testing and benchmarking these sensors has a large significance for heavy truck manufacturers such as Scania.In order to test these components, a rig assembly was constructed. In this project a LabVIEW program was developed for controlling the rig and gathering the required data. The aim of the rig was to try and simulate the behaviour of the components that are commonly measured in the gearbox or the engine, as well as use it for testing and benchmarking new rotational speed sensors. In order to achieve this, di˙erent processes were studied that cover certain working conditions in a Scania truck. The rig’s ability to follow these processes was then studied. In addition, a test case for inductive and Hall sensors was also presented.It is shown that the implemented solution for testing the sensors can be used for benchmarking di˙erent sensors and can be a useful tool for future sensor development at Scania. However, the rig with its current hardware was unable to closely replicate processes that are of interest. There are a lot of improvements that have to be made in order to properly simulate the behaviour of the powertrain components that are of interest for speed sensor applications. / Information gällande hastigheten och riktningen på de olika axlarna i växellådan och motorn hos tunga fordon blir alltmer viktig, särskilt när fordonsindustrin går mot au-tonoma fordon. Det vanligaste sättet att mäta dessa parametrar idag är med induktiva-eller Hall-givare. Provning och utvärdering av dessa givare är därmed av stor betydelse för en fordonstillverkare som Scania.I detta projekt har en rigg designats för att testa dessa komponenter. Ett LabVIEW program har utvecklats för att styra riggen samt samla all relevant data med avseende på givarutveckling. Syftet med riggen var att simulera beteendet hos de komponenter i växellådan eller motorn som övervakas av dessa givare samt att använda riggen för att testa och jämföra nya varvtalsgivare. För att uppnå detta, undersöktes ett antal processer som täcker ett urval av driftsfall i en Scania lastbil. Riggens förmåga att återskapa dessa processer undersöktes. Utöver detta presenterades även ett testfall för induktiva- och Hall-givare.Den implementerade lösningen för provning av givare visas kunna användas för att jämföra olika givare och kan vara ett användbart verktyg för framtida givarutveckling på Scania. Däremot kan riggen inte återskapa de processer som är intressanta med den hårdvara som var tillgänglig vid tillfället. Förbättringar av riggens hårdvara måste göras för att kunna simulera de drivlinekomponenterna som är av intresse för utveckling av varvtalsgivare.
255

ANPASSAD TRÄNING UTIFRÅN MENSTRUATIONSCYKELN: FYSIOTERAPEUTERS PERSPEKTIV : En kvalitativ intervjustudie

Zulfiyeva, Günaj, Roskifte, Rakel January 2024 (has links)
Bakgrund: Trots ökat intresse kring menstruationscykelns påverkan på idrottares prestationer råder oenighet bland forskare och kliniker avseende effekterna av anpassningen och praktiska tillvägagångssätt för att justera träningen utifrån menstruationscykeln. Att öppet diskutera menstruationscykeln inom idrottsvärlden anses ännu tabu. Fysioterapeuten är den främsta medicinska kontakten bland kvinnliga idrottare och kan påverka idrottarnas prestationer. Det är därför intressesant att studera fysioterapeuternas inställningar och upplevelser kring ämnet. Syfte: Syftet med studien var att undersöka fysioterapeuters inställning till och upplevelser av att anpassa kvinnliga elitidrottares träning utifrån menstruationscykeln och samtalsmiljön kring detta. Metod: Studien var en kvalitativ beskrivande design. Ändamålsenligt- och snöbolls-urval användes vid rekrytering. Sex fysioterapeuter rekryterades och intervjuades utifrån en semi-strukturerade intervjuer. Data analyserades genom kvalitativ innehållsanalys med induktiv ansats. Resultat: Analysen av data ledde till identifieringen av 14 underkategorier som fördelades inom fyra huvudkategorier: Praktiska erfarenheter av genomförda träningsanpassningar, Fysioterapeuternas attityder till att anpassa träning, Erfarenheter av omgivningsfaktorer och samtal, och Omständigheter som påverkar träningsanpassning. Slutsats: Resultatet beskriver hur fysioterapeuters praktiskt genomförda anpassningar av träningen utifrån menstruationscykeln, exempelvis genom att justera idrottarnas träningsintensitet. Resultaten bekräftar att fysioterapeuterna upplever en brist på evidens för systematiska anpassningar av träning baserat på menstruationscykeln, och att samtalsämnet fortfarande till viss det är tabubelagt. / Background: Despite increased interest in the menstrual cycles impact on athletes’ performances, there is disagreement among researchers and clinicians regarding both the effects of adaptation and practical approaches to adjust training based on the menstrual cycle. Challenges also persist in openly discussing the “menstrual cycle” within the sports world. The physiotherapist is the primary medical contact for female athletes and can thus influence their performances. Therefore, it is of interest to study physiotherapists’ attitudes and experiences on the subject. Aim: The purpose of the study was to investigate physiotherapists’ attitudes toward and experiences of adapting training for female elite athletes based on the menstrual cycle and the conversation environment surrounding it. Method: The study had a qualitative descriptive design. Convenience and snowball sampling were used in the recruitment process. Six physiotherapists were recruited and interviewed through semi-structured interviews. The data were analyzed using qualitative content analysis with an inductive approach. Results: The data analysis resulted in the identification of 14 subcategories distributed within four main categories: Practical experiences of adapting training, Physiotherapists’ attitudes towards training adaptation, Experiences of environmental factors and conversations, and Circumstances affecting adaptation of training. Conclusion: The result describes how physiotherapists practically implement adaptations of training based on the menstrual cycle, such as adjusting training intensity. The results confirm that physiotherapists perceive a lack of evidence for systematic adjustments in training based on the menstrual cycle, and the subject is still perceived as tabu.
256

Synergetic Attenuation of Stray Magnetic Field in Inductive Power Transfer

Lu, Ming 28 July 2017 (has links)
Significant stray magnetic field exists around the coils when charging the electric vehicles (EVs) with inductive power transfer (IPT), owning to the large air gap between the transmitter and receiver. The methods for field attenuation usually introduce extra losses and reduce the efficiency. This study focuses on the synergetic attenuation of stray magnetic field which is optimized simultaneously with the efficiency. The optimization is realized with Pareto front. In this dissertation, three methods are discussed for the field attenuation. The first method is to tune the physical parameters of the winding, such as the inner radii, outer radii, distribution of the turns, and types of the litz wires. The second method is to add metal shields around the IPT coils, in which litz wires are used as shields to reduce the shielding losses. The third method is to control the phases of winding currents, which avoids increasing the size and weight of the IPT coils. To attenuate the stray magnetic field by tuning the physical parameters, the conventional method is to sweep all the physical parameters in finite-element simulation. This takes thousands of simulations to derive the Pareto front, and it's especially time-consuming for three-dimensional simulations. This dissertation demonstrates a faster method to derive the Pareto front. The windings are replaced by the lumped loops. As long as the number of turns for each loop is known, the efficiency and magnetic field are calculated directly from the permeance matrices and current-to-field matrices. The sweep of physical parameters in finite-element simulation is replaced by the sweep of the turns numbers for the lumped loops in calculation. Only tens of simulations are required in the entire procedure, which are used to derive the matrices. An exemplary set of coils was built and tested. The efficiency from the matrix calculation is the same as the experimental measurement. The difference for stray magnetic field is less than 12.5%. Metal shields attenuate the stray magnetic field effectively, but generates significant losses owning to the uneven distribution of shield currents. This dissertation uses litz wires to replace the conventional plate shield or ring shield. Skin effect is eliminated so the shield currents are uniformly distributed and the losses are reduced. The litz shields are categorized to two types: shorted litz shield and driven litz shield. Circuit models are derived to analyze their behaviors. The concept of lumped-loop model is applied to derive the Pareto front of efficiency versus stray magnetic field for the coils with litz shield. In an exemplary IPT system, coils without metal shield and with metal shields are optimized for the same efficiency. Both the simulation and experimental measurement verify that the shorted litz shield has the best performance. The stray magnetic field is attenuated by 65% compared to the coils without shield. This dissertation also introduces the method to attenuate the stray magnetic field by controlling the phases of winding currents. The magnetic field around the coils is decomposed to the component in the axial direction and the component in the radial direction. The axial component decreases with smaller phase difference between windings' currents, while the radial component exhibits the opposite property. Because the axial component is dominant around the IPT coils, decreasing the phase difference is preferred. The dual-side-controlled converter is applied for the circuit realization. Bridges with active switches are used for both the inverter on the transmitter side and the rectifier on the receiver side. The effectiveness of this method was verified both in simulation and experiment. Compared to the conventional series-series IPT with 90° phase difference between winding currents, stray magnetic field was attenuated by up to 30% and 40% when the phase differences of winding currents are 50° and 40°, respectively. Furthermore, an analytical method is investigated to calculate the proximity-effect resistance of the planar coils with ferrite plate. The objective of this method is to work together with the fast optimization which uses the lumped-loop model. The existence of the ferrite plate complicates the calculation of the magnetic field across each turn which is critical to derive the proximity-effect resistance. In this dissertation, the ferrite plate is replaced by the mirrored turns according to the method of image. The magnetic fields are then obtained from Ampere's Law and Biot-Savart Law. Up to 200 kHz, the difference of the proximity-effect resistance is less than 15% between calculation and measurement. / Ph. D. / Inductive power transfer for the battery charging of electric vehicles uses loosely coupled coils to replace the cables and plugs. The power is transferred from transmitter to receiver across tens of centimeters. Significant stray magnetic field exists around the coils owning to the large gap, which should be attenuated for the safety consideration of human beings. Three methods are discussed for the field attenuation. The first method is to tune the physical parameters of the winding, such as the inner radii, outer radii, distribution of the turns, and types of the litz wires. The second method is to add metal shields around the IPT coils, in which litz wires are used as shields to reduce the shielding losses. The third method is to control the phases of winding currents, which avoids the increase of the size and weight of the IPT coils. However, the field attenuation usually comes with reduced efficiency of the system. The work in this dissertation is focused on the synergetic attenuation of stray magnetic field in inductive power transfer for electric vehicles. The optimization is realized with Pareto front. The coils are optimized for low stray magnetic field and high efficiency simultaneously.
257

Die verband tussen ideaal en werklikheid ten opsigte van die funksionering van die pneumatika in der erediens van die AGS van Suid-Afrika

Van Den Berg, Jan Christoffel 11 1900 (has links)
Text in Afrikaans / Summaries in English and Afrikaans / 'n Onderskeidende kenmerk van die Pinksterbeweging (waarvan die AGS deel is) wat aan die begin van hierdie eeu tot stand gekom het, was die funksionering van die pneumatika (die geestelike gawes in 1 Korintiers 12:7-11 genoem) in die lewens van lidmate en in die liturgie van die erediens. Die opkoms van die Charismatiese beweging vanaf die sestigerjare het hierdie fenomeen opnuut onder die aandag van die kerk gebring. Histories blyk dit dat die funksionering van die pneumatika 'n integrale deel van die bemoeienis van God met die mens was. Sommige van die pneumatika was reeds in die Ou Testament teenwoordig, is prominent in die bediening van Jesus gesien tydens sy vleeslike bestaan, en was kenmerkend van die kerklike lewe in apostoliese tye. In die na-apostoliese tye was daar 'n merkbare afuame hiervan, maar het selfs in die middeleeue nooit heeltemal van die toneel verdwyn het nie. Vanaf die twaalfde eeu was daar weer 'n gestadigde toename in die voorkoms van die pneumatika wat sy klimaks bereik in die wereldwye Pinksterherlewing aan die begin van die twintigste eeu. Die teoretiese teologiese teorie binne die AGS hou die ideaal voor dat die pneumatika steeds op Nuwe Testamentiese wyse (soos deur die AGS geinterpreteer) in die erediens sal funksioneer. 'n Empiriese ondersoek met behulp van 'n situasie-analise (Wallace se model van deduktiewe en induktiewe redenering) toon aan dat daar 'n beduidende verskil tussen ideaal en praktyk is - die pneumatika funksioneer slegs sporadies in die eredienste, terwyl lidmate se betrokkenheid daarby en kennis daarvan dienooreenkomstig van beperkte aard is. n V erstelde praktykteorie word voorgestel. Dit behels 'n model wat die interathanklikheid en relasie aandui tussen Christus as Hoof van die gemeente en Bron van die pneumatika, lidmate en pastore se houding en kennis in verband hiermee, en die ruimte vir en implementering van die pneumatika in die erediens. Fasiliterend tot hierdie interaktiewe proses is die doping in die Heilige Gees, opleidingsprogramme, en kleingroepe. Hierdie praktykteorie is oop vir toekomstige toetsing en verstelling - alles moet lei na die herstel van die funksionering van die pneumatika tot opbou van die gemeente en meerdere verheerliking van God. / A distinctive characteristic of the Pentecostal Movement (of which the AFM is a part), formed at the beginning of this century, was the functioning of the pneumatics (the spiritual gifts mentioned in 1 Corinthians 12:7-11) in the lives of members and in the liturgy of their worship service. The Charismatic Movement arising in the sixties brought this phenomenon under the attention of the church anew. Historically it seems that the pneumatics were a integral part of the activities of God with his people. Some of the pneumatics were already present in the Old Testament, were seen in the earthly ministry ofJesus, and were distinctive of the apostolic period. In the after-apostolic period there was a marked decline in the appearance thereof From the twelfth century onwards there was an increase in the appearance of the pneumatics that climaxed in the worldwide Pentecostal revival at the beginning of this century. The theoretical theological theory in the AFM presents the ideal that the pneumatics would still be operating, as in New Testament times (i.e. as interpreted by the AFM), in their worship services. An empirical survey with the aid of a situation analysis (yv allace' s model of deductive and inductive reasoning was used), shows that there is a marked difference between ideal and practice - the pneumatics are operating sporadically and on a limited scale in the worship services, whilst the participation of the members and their knowledge in this regard are accordingly limited. An improved practice theory is suggested. It entails an interactive model that shows the interdependency and relation between Christ as head of the church and source of the pneumatics, church members and pastors whose attitude and knowledge in connection with this are of utmost importance, and the place for and implementing of the pneumatics in the worship service. Facilitating this interactive process is the baptism in the Holy Spirit, teaching programmes, and small groups. This practice theory is open for future testing and improvement - this must all lead to the restoring of the functioning of the pneumatics for the edification of the church and the greater glorifying of God. / Philosophy, Practical & Systematic Theology / Th. D. (Practical Theology)
258

Active and Passive Vibration Isolation and Damping via Shunted Transducers

de Marneffe, Bruno 14 December 2007 (has links)
<p align="justify">Many different active control techniques can be used to control the vibrations of a mechanical structure: they however require at least a sensitive signal amplifier (for the sensor), a power amplifier (for the actuator) and an analog or digital filter (for the controller). The use of all these electronic devices may be impractical in many applications and has motivated the use of the so-called shunt circuits, in which an electrical circuit is directly connected to a transducer embedded in the structure. The transducer acts as an energy converter: it transforms mechanical (vibrational) energy into electrical energy, which is in turn dissipated in the shunt circuit. No separate sensor is required, and only one, generally simple electronic circuit is used. The stability of the shunted structure is guaranteed if the electric circuit is passive, i.e., if it is made of passive components such as resistors and inductors.</p> <p align="justify">This thesis compares the performances of the electric shunt circuits with those of classical active control systems. It successively considers the use of piezoelectric transducers and that of electromagnetic (moving-coil) transducers.</p> <p align="justify">In a first part, the different damping techniques are applied on a benchmark truss structure equipped with a piezoelectric stack transducer. A unified formulation is found and experimentally verified for an active control law, the Integral Force Feedback (IFF), and for various passive shunt circuits (resistive and resistive-inductive). The use of an active shunt, namely the negative capacitance, is also investigated in detail. Two different implementations are discussed: they are shown to have very different stability limits and performances.</p> <p align="justify">In a second part, vibration isolation with electromagnetic (moving-coil) transducers is introduced. The effects of an inductive-resistive shunt circuit are studied in detail; an equivalent mechanical representation is found. The performances are compared with that of resonant shunts and with that of active isolation with IFF. Next, the construction of a six-axis isolator based on a Stewart Platform is presented: the key parameters and the main limitations of the system are highlighted.</p>
259

Lógicas probabilísticas com relações de independência: representação de conhecimento e aprendizado de máquina. / Probabilistic logics with independence relationships: knowledge representation and machine learning.

Ochoa Luna, José Eduardo 17 May 2011 (has links)
A combinação de lógica e probabilidade (lógicas probabilísticas) tem sido um tópico bastante estudado nas últimas décadas. A maioria de propostas para estes formalismos pressupõem que tanto as sentenças lógicas como as probabilidades sejam especificadas por especialistas. Entretanto, a crescente disponibilidade de dados relacionais sugere o uso de técnicas de aprendizado de máquina para produzir sentenças lógicas e estimar probabilidades. Este trabalho apresenta contribuições em termos de representação de conhecimento e aprendizado. Primeiro, uma linguagem lógica probabilística de primeira ordem é proposta. Em seguida, três algoritmos de aprendizado de lógica de descrição probabilística crALC são apresentados: um algoritmo probabilístico com ênfase na indução de sentenças baseada em classificadores Noisy-OR; um algoritmo que foca na indução de inclusões probabilísticas (componente probabilístico de crALC); um algoritmo de natureza probabilística que induz sentenças lógicas ou inclusões probabilísticas. As propostas de aprendizado são avaliadas em termos de acurácia em duas tarefas: no aprendizado de lógicas de descrição e no aprendizado de terminologias probabilísticas em crALC. Adicionalmente, são discutidas aplicações destes algoritmos em processos de recuperação de informação: duas abordagens para extensão semântica de consultas na Web usando ontologias probabilísticas são discutidas. / The combination of logic and probabilities (probabilistic logics) is a topic that has been extensively explored in past decades. The majority of work in probabilistic logics assumes that both logical sentences and probabilities are specified by experts. As relational data is increasingly available, machine learning algorithms have been used to induce both logical sentences and probabilities. This work contributes in knowledge representation and learning. First, a rst-order probabilistic logic is proposed. Then, three algorithms for learning probabilistic description logic crALC are given: a probabilistic algorithm focused on learning logical sentences and based on Noisy-OR classiers; an algorithm that aims at learning probabilistic inclusions (probabilistic component of crALC) and; an algorithm that using a probabilistic setting, induces either logical sentences or probabilistic inclusions. Evaluation of these proposals has been performed in two situations: by measuring learning accuracy of both description logics and probabilistic terminologies. In addition, these learning algorithms have been applied to information retrieval processes: two approaches for semantic query extension through probabilistic ontologies are discussed.
260

Métodos geofísicos aplicados na avaliação ambiental em uma indústria química na cidade de São Paulo - SP / Geophysical Methods applied in the Environmental Evaluation of a Chemical Industry in the city of São Paulo SP

Marina Minozzo 11 September 2009 (has links)
O uso cada vez maior de derivados de petróleo em processos industriais proporciona a geração de uma diversidade de produtos cada vez mais utilizados pela sociedade atual. As conseqüências negativas do uso e manipulação de hidrocarbonetos é a geração de resíduos e efluentes altamente poluidores. Atualmente, a utilização integrada de técnicas geofísicas podem se constituir em uma ferramenta eficiente na avaliação e caracterização de problemas ambientais. De uma forma geral a utilização da geofísica na caracterização de uma área afetada por substâncias poluentes consiste na detecção e mapeamento da extensão da área afetada e informações sobre a profundidade da zona saturada, direção do fluxo subterrâneo e profundidade do substrato rochoso inalterado. O objetivo principal deste trabalho foi a caracterização geofísica de uma área contaminada por hidrocarbonetos derivados de petróleo, por meio da utilização dos métodos: Eletroresistividade, Polarização Induzida e Eletromagnético Indutivo. Esta caracterização foi realizada através de ensaios de campo e do uso de modelos bidimensionais, tendo como área de estudo uma indústria química localizada no município de São Paulo SP. Esta área foi escolhida com base em estudos precedentes que indicam a ocorrência de contaminação. Os resultados dos modelos de resistividade, cargabilidade e condutividade aparente sugerem a presença de contaminação e seu caminho preferencial, que segue o sentido do fluxo da água subterrânea. Três tipos de anomalias puderam ser individualizadas: a primeira, de baixa resistividade e baixa cargabilidade, que sugerem contaminação mais antiga e a relação com os processos de biodegradação, confirmada através das análises de bactérias; a segunda, de baixa resistividade e alta cargabilidade, geradas pela presença de materiais polarizáveis (metais); e a terceira, as anomalias de alta resistividade e baixa cargabilidade, geradas pela presença do contaminante bruto (sedimento impregnado por tinta), que confirma a contaminação mais recente onde não ocorre processo de biodegradação. / The increasing usage of petroleum derivatives in industrial processes provides a generation of products which are being increasingly used by the contemporary society. The negative consequence from the use and manipulation of hydrocarbons is the generation of residues and highly pollutant effluents. Nowadays, the integrated usage of geophysical techniques can become an efficient tool in the evaluation and characterization of environmental problems. In general, the usage of geophysical in the characterization of an area affected by pollutant substances consists in mapping and detecting the extension of the affected area and inform about the saturated zone deep, the underground flux direction and the deep of the unaltered rocky substrate. The main objective of this research was the geophysical characterization of contaminated area by hydrocarbons derived from petroleum, by the usage of the following methods: Electrical resistivity, Inducted Polarization, and Inductive Electromagnetic. This characterization was carried out through field rehearsals and the usage of two-dimensional models in a chemical industry as study area, placed in the city of São Paulo SP. This area was chosen as the basis in precedent studies which has indicated the event of contamination. The results from the resistivity, chargeability and apparent conductivity models, suggest the presence of contamination and its favorable way, which follows the underground water flux. Three kinds of anomalies could be individualized: first, low resistivity and low chargeability, which suggest older contamination and the relation with the biodegradation processes, confirmed thought the bacterial analysis; second, low resistivity and high chargeability, generated by the presence of polarizable materials (metals); and third, the high resistivity anomalies and low chargeability, generated by the presence of the raw contaminant (paint impregnated sediment), which confirms the most recent pollution where the biodegradation process does not occur.

Page generated in 0.0613 seconds