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Daniels, Simone Monique. "Water management strategies for polymer electrolyte fuel cells (PEFCs) employing microchannel flowfields." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/20033.
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Polymer electrolyte fuel cells (PEFCs) represent a promising energy conversion technology for automotive and portable applications. In order to achieve the high power densities required for these applications, the fuel cell needs to be operated in the high current density region where the rate of water production is at a maximum. This typically leads to the build-up of liquid water in the porous media and flowfield compartments of the fuel cell. The build-up of liquid water inhibits reactant gas transport to the catalyst layer, leading to a phenomenon called flooding. Flooding causes a rapid drop in cell voltage and is detrimental to fuel cell performance and durability. Microchannel flowfield designs possess characteristics which could potentially improve water removal from the fuel cell and also reduce the fuel cell system complexity. There is limited knowledge on the use of microchannels flow field designs in PEFCs, specifically how different operating conditions and different membrane electrode assembly (MEA) designs affect the overall performance and water management of a fuel cell using microchannel flow fields. This study investigated two water management strategies for PEFCs employing microchannel flowfields, namely manipulation of operating conditions and modification to the design of components within the MEA. Four different gas diffusion layer (GDL) cases were tested in a single cell environment at four different cathode flowrates and stoichiometric ratios. The cases consisted of a carbon GDL and three variants of a uniform structured metal GDL. The three metal GDL designs varied in terms of the wettability of the microporous layer coated on the surface of the metal GDL. Several in-situ diagnostic tests, namely polarisation curves, electrochemical impedance spectroscopy (EIS), pressure drop and voltage stability tests were conducted to determine the overall fuel cell performance and water management characteristics of the different GDL cases.
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Chen, Cheng. "Membrane degradation studies in PEMFCs." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29712.
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Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2010.Committee Chair: Fuller, Thomas; Committee Member: Beckham, Haskell; Committee Member: Hess, Dennis; Committee Member: Koros, William; Committee Member: Meredith, Carson. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Hanna, Maha. "Étude physico-chimique de liquides ioniques pour PEMFCs." Phd thesis, Grenoble INPG, 2008. http://www.theses.fr/2008INPG0164.
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Les liquides ioniques pourront remplacer l'eau dans les électrolytes des PEMFCs opérant à 130°C. Les liquides ioniques résultant de la neutralisation des amines aliphatiques par l'acide trifluoromethanesulfonique montrent que les points de fusion dépendent de plusieurs critères, nature de l'anion, nature des substitutions sur l'amine. D'autre part, la majorité de ces sels sont thermiquement stables jusqu'à 400°C. L'étude par la voltamétrie cyclique a prouvé que les amines et les sels (HNR3+, A) s'oxydent à des potentiels très élevés (> 1,9 V/ESH), compatible avec leur utilisation dans les piles à combustible. D'autre part, les meilleures conductivités sont obtenues par les sels résultant de l'association acide trifluoromethanesulfonique et amines dissymétriques. Les conductivités à 130°C sont entre 5 mS. Cm-1 et 45 mS. Cm-1. L'incorporation de ces composés dans le Nafion a donné une bonne compatibilité LIP/Nafion. Cependant, l'effet plastifiant du LIP sur le polymère diminue les propriétés mécaniques du Nafion. Les conductivités sont aussi nettement réduites d'un facteur de 5 dans les meilleurs casIonic liquids can replace water in the electrolytes of PEMFCs systems operating at 130°C. Ionic liquids resulting from the neutralization of aliphatic amines by trifluoromethanesulfonic acid show that the melting point depends on several criteria, nature of the anion, nature of the substitutions on the amine. Moreover, the majority of these salts are thermally stable upto 400°C. The study by cyclic voltammetry showed that the amines and the salts (HNR3+, A-) are stable towards very oxidative step (i. E. > 1. 9 V/HSE), compatible for their use in fuel cell. In the other hand, the best conductivity behaviour is observed for salts resulting from dissymmetric amines/ trifluoromethanesulfonic acid association. The conductivities at 130°C lie between 5 mS. Cm-1 and 45 mS. Cm-1. The incorporation of these compounds within Nafion shows good compatibility PIL/ Nafion. However, the plastizing effect of PIL in the polymer reduces the Nafion mechanical properties. The conductivities are also dramatically reduced by a factor of 5 in the best cases
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Jalilian, E. "Characterization of progenitors of endothelial cells (PECs)." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1560479/.
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There are a number of different stem cell sources that have the potential to be used as therapeutics in vascular degenerative diseases such as diabetic retinopathy. On the one hand, there are so called endothelial progenitor cells (EPCs), which are typically derived from adult blood. They carry the marker CD34, but the true nature and definition of EPCs is still controversial. On the other hand, there are embryonic precursors of endothelial cells (PECs), which also express CD34, and which can be differentiated from embryonic stem cells (ESCs) or induced pluripotent stem cells (iPSCs) in vitro. Furthermore, a subpopulation of human umbilical cord endothelial cells (HUVECs) has also been shown to express CD34. In this study, It was aimed to compare these three different CD34 positive cell populations by full genome transcriptional profiling (RNAseq). To this end I firstly optimised a PEC differentiation protocol and found that VEGF is critical for the transition from mesodermal precursors to PECs. Secondly, I found signalling pathways that regulate CD34 expression in HUVECs and showed a close correlation between CD34 expression and the endothelial tip/stalk cell phenotypes. Thirdly, principal component analysis (PCA) of RNAseq data showed that blood-derived EPCs are fundamentally different from iPS-derived PECs. Lastly, I also identified from RNAseq data number of potentially novel PEC markers. Once validated such novel markers of PECs and EPCs will be useful to better define these cell populations, facilitating the translation of regenerative approaches in this field as well as providing potentially novel diagnostic tools.
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Praillet, Thierry. "Caractérisation fonctionnelle du locus pecS d'Erwinia chrysanthemi." Lyon, INSA, 1997. http://www.theses.fr/1997ISAL0039.
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La macération des tissus végétaux provoquée par la bactérie phytopathogène Erwinia chrysanthemi est liée à la sécrétion par cette bactérie de nombreuses enzymes lytiques de la paroi végétale. La régulation de l'expression de ces enzymes fait intervenir différents loci génétiques. Parmi ceux-ci, le locus pecS contrôle à la fois la synthèse et la sécrétion des pectinases et des cellulases. Ce dernier est constitué de deux gènes pecS' et pecM transcrits de façon divergente, dont les produits sont tous deux impliqués dans la même voie de régulation. La caractérisation biochimique et fonctionnelle du régulateur PecS a fait l'objet de notre travail. Le régulateur PecS se caractérise par une masse moléculaire monomérique de 18 kDa, un point isoélectrique proche de la neutralité (pl= 6. 5) et semble actif sous forme dimérique. La comparaison de la séquence de la protéine PecS avec celles des banques de données révèle que PecS présente une homologie significative avec les protéines de la famille MarR, impliquées dans la régulation transcriptionnelle de l'expression de gènes de résistance ù des produits toxiques. Malgré l'absence d'un site classique d'interaction avec l'ADN, la protéine PecS interagit spécifiquement avec les régions régulatrices des gènes dont elle module l'expression in vivo. Malgré cette interaction spécifique entre la protéine PecS et l'ADN, aucune séquence consensus fixant la protéine PecS n'a pu être déterminée. La protéine PecS régule l'expression de son propre gène, ainsi que celle du gène pecM adjacent. Parallèlement, nous avons montré que la protéine PecM est nécessaire à la pleine activité régulatrice de PecS. Les analyses physiologiques antérieures permettent de supposer l'intervention du couple PecS/PecM dans la réception d'un signal émis au cours des réactions de défense de la plante peut être envisagée. Ainsi. Le couple PecS/PecM pourrait constituer un système régulateur de l'expression des facteurs de virulence d' E. Chrysanthemi au cours de l'infection en réponse à un signal non encore déterminéThe phytopathogenic bacterium Erwinia chrysanthemi is responsible for soft-rot diseases of many plants. This soft-rotting activity is mainly due to the ability of the bacterium to secrete large amounts of depolymerizing enzymes (pectinases, cellulases) attacking the middle lamella of the plant tissues. The regulation of these enzymes is subjected to a complex regulatory network. In this network, the PecS protein down-regulates the synthesis of cellulases and pectinases. In this thesis, we present the biochemical and functional characterization of the PecS repressor. After overproduction and purification of the PecS protein, biochemical analysis reveals that this protein is characterized by a molecular mass of 18 kDa, an isoelectric point next to 6. 5 and probably acts in the cell as a dimer. Computer assisted proteinic sequence comparison reveals that PecS is homologous to the MarR family of transcriptional regulator. This family of transcriptional regulators docs not present any classical DNA-binding domain in the primary sequence. Functionally, the PecS protein interacts specifically with the regulatory regions of the in vivo controlled genes. Meanwhile, no consensus for the PecS binding site was detected. The PecS protein downregulates the expression of its O\VD gene as these of the adjacent pecM gene. Reciprocally, the PecM protein is needed for the full regulatory activity of PecS. Preliminary physiological studies suggest that the PecS/PecM couple could be involved in the reception of a signal liberated by the plant defense reactions. So, these two regulators could constitute a regulatory system of virulence factor synthesis during plant infection
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Karlsson, Alexandra. "Attityder till certifieringssystemen FSC och PEFC i skogsbranschen." Thesis, Linnéuniversitetet, Institutionen för biologi och miljö (BOM), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-38481.
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Different groups in the forestry sector were likely to have different views regarding the responsibility for an environmentally sustainable forestry and the benefits of certification and this study aimed to examine the attitudes that existed in the forestry sector to the certification schemes FSC and PEFC. In the study a survey and a questionnaire were sent out to different groups. The investigation was made with respect to three groups: forest owners, forest contractors and employees working with the certification schemes on a daily basis at the forest company Södra. The groups agreed that the owner of the forest had the main responsibility for an environmentally sustainable forestry. The study revealed that all three groups highly valued the environmental aspect of certification. Forest owners also identified financial gain as a benefit. The forest contractors felt that the certification gave orderliness to their work but also saw an economic cost from being certified. The forest company employees found certification as an access to a widermarket with certified products. Half of the forest owners estimated their knowledge of the certification schemes to be inadequate while forest contractors and the employees of Södra valued their knowledge as sufficient. The forest owners had less education about the certification schemes than the other groups.Olika grupper i skogsbranschen riskerar att ha olika syn när det gäller ansvaret för ett miljömässigt hållbart skogsbruk och nyttan med certifiering och den här studien gjordes för att undersöka vilka inställningar som fanns i skogsbranschen till certifieringssystemen FSC och PEFC. Arbetet gjordes med avseende på tre grupper: skogsägare, skogsentreprenörer och anställda som arbetar på skogsföretaget Södra med certifiering i sitt dagliga arbete. I studien skickades en enkät och ett frågeformulär ut. Undersökningen visade att de tre grupperna värderade miljömässigt hållbart skogsbruk med certifiering högt. Som skogsägare fick man en certifieringspremie för det certifierade virke som man sålde. Skogsägarna såg också en ekonomisk vinning med certifiering. Skogsentreprenörerna ansåg att certifiering i högre grad gav ordning och reda i deras arbete men att det fanns en ekonomisk kostnad med att vara certifierad. Skogsföretagsgruppen menade att certifierade produkter gav tillgång till en större marknad för skogsföretaget. Grupperna var överens om att ansvaret för ett miljömässigt hållbart skogsbruk låg på de/den som ägde skogsmarken. Samtidigt uppskattade hälften av skogsägarna att deras kunskaper om certifieringarna var otillräckliga medan skogsentreprenörerna och skogsföretagsgruppen ansåg att deras kunskaper var tillräckliga. Detta kunde bero på att skogsägarna fick mindre utbildning av certifiering än de andra två grupperna. Det här arbetet har visat att grupperna inte har olika syn när det gäller vikten av att ett miljömässigt hållbart skogsbruk bedrivs.
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Tessier, Béatrice Claire. "Preparation, characterisation and evaluation of core-shell electrocatalyst for PEMFCs." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/142773/.
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For oxygen reduction catalysis it has been shown that thin layers of platinum (shell) over a non-Pt core enhance the activity. In addition surface science studies have found that overlayers of one metal on another strongly modifies the electrocatalytic properties of the surface metal. The aim of this project is to develop this concept by the preparation of practical fuel cell catalysts based on the core-shell model and gain a fundamental understanding of their properties and behaviour. A key aspect of the work is to establish the physical characteristics required for a catalyst to show long-term stability as well as improved activity. Chapter 1 introduces the PEM fuel cells, ORR electrocatalysts and the preparation and characterisation of core-shell type electrocatalysts. The experimental techniques, procedures and apparatus used for this work will be described in Chapter 2. The mechanism of the synthetic controlled-surface reaction (CSR) used to prepare the coreshell electrocatalysts was studied in Chapter 3. Then the focus will be on the palladiumcore and platinum-shell system in Chapter 4 and 5, where the effects of the Pt shell and the Pd core size on the electrocatalysts properties are investigated. The electrocatalysts prepared for these studies were assessed for their electrochemical stabilities and their ORR activities. Finally, Chapter 6 presents preliminary results on the iridium-core and platinumshell system. The deposition of Pt on Pd and Ir cores using the CSR did not lead to a complete Pt coverage as Pt tended to deposit preferentially at the edges and corners on the core surface and then on Pt. Whereas an enhancement in the electrochemical stability of the Pt/Pd coreshell electrocatalysts was observed compared to a pure Pt electrocatalyst, the Pt/Ir coreshell showed poorer stability than Pt. Benefits in the ORR activity were gained with both the Pt/Pd and Pt/Ir core-shell electrocatalysts. This demonstrates that, due to the original properties of the core-shell-structured electrocatalysts, it is possible to use less Pt and still obtain an improvement in the ORR activity.
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Мороз, Людмила Василівна, and Liudmyla Vasylivna Moroz. "Розвиток комунікації дітей із розладами аутичного спектру засобами PECS." ФОП Цьома С. П, 2019. http://repository.sspu.sumy.ua/handle/123456789/7549.
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Останніми роками у спеціальній освіті спостерігається значна активізація інтересу до проблеми аутизму. Це зумовлено постійним збільшенням виявлення означеного розладу серед дітей, науковими даними щодо природи та сутності даного порушення, а також накопиченням практичного досвіду корекційно-логопедичної роботи із означеною категорією дітей та створенням можливостей для їх прийнятного функціонування у суспільстві.In recent years, special education has seen a significant increase in interest in autism. This is due to the constant increase in the detection of the specified disorder among children, scientific data on the nature and essence of the violation, as well as the accumulation of practical experience of corrective speech therapy with the specified category of children and creating opportunities for their acceptable functioning in society.
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Nero, Hanna. "Traktdirektiv enligt PEFC – effektiv kommunikation från skogsägare till skogsbolag." Thesis, Linnéuniversitetet, Institutionen för skog och träteknik (SOT), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-65330.
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Skogen innehåller höga värden i form av naturvärden och forn- och kulturlämningar. Dessa måste skyddas när skogen brukas för ekonomisk vinning och hur det ska ske framgår främst i arbetsbeskrivningen för varje objekt, kallat traktdirektiv. För att se var bristerna finns har inköpare/planerare samt maskinförare/entreprenörer intervjuats. En mall för utformandet av traktdirektiven skulle underlätta för alla och gynna de höga värdena i skogen.
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Alayyaf, Abdulmajeed A. "Synthesis of Two Monomers for Proton Exchange Membrane Fuel Cells (PEMFCs)." Digital Commons @ East Tennessee State University, 2016. https://dc.etsu.edu/etd/3015.
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The overall goal of this research is to synthesize two different monomers for proton exchange membrane (PEM) Fuel Cells. Such monomers are proposed to be polymerized to improve the efficiency and compatibility of electrodes and electrolytes in PEM fuel cells.
The first target is to synthesize 4-diazonium-3-fluoro PFSI zwitterionic monomer. Three steps were carried out in the lab. First one was the ammonolysis of 3-fluoro-4-nitrobenzenesulfonyl chloride. Second reaction was the bromination of Nafion monomer. The next coupling reaction, between brominated Nafion monomer and the 3-fluoro-4-nitrobenzenesulfonamide, was failed. The obstacles involve the harsh reaction condition and troublesome purification procedure.
The second target is to synthesize 5-nitro-1, 3-benzenedisulfonamide. According to the literature, this synthesis was also designed as three steps: 1)nitration of sodium 1, 3-benzenedisulfonate salt; 2)chlorination of sodium 5-nitro-1, 3-benzenedisulfonate salt; and 3)ammonolysis of 5- nitro-1, 3- benzenedisulfonyl chloride. This monomer is expected to be copolymerized for membrane electrolyte in PEM fuel cells.
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Eaton, Brandon Michael. "One Dimensional, Transient Model of Heat, Mass, and Charge Transfer in a Proton Exchange Membrane." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/32788.
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A transient, one-dimensional, model of the membrane of a proton exchange membrane fuel cell is presented. The role of the membrane is to transport protons from the anode to cathode of the fuel cell while preventing the transport of other reactants. The membrane is modeled assuming mono-phase, multi-species flow. For water transport, the principle driving forces modeled are a convective force, an osmotic force (i.e. diffusion), and an electric force. The first of these results from a pressure gradient, the second from a concentration gradient, and the third from the migration of protons from anode to cathode and their effect (drag) on the dipole water molecules. Equations are developed for the conservation of protons and water, the conservation of thermal energy, and the variation of proton potential within the membrane.
The model is solved using a fully implicit finite difference approach. Results showing the effects of current density, pressure gradients, water and heat fluxes, and fuel cell start-up on water concentration, temperature, and proton potential across the membrane are presented.Master of Science
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Gupta, Gaurav. "Bimetallic Platinum-Chromium Nanoparticles as electrocatalysts for proton exchange membrane fuel cells (PEMFCs)." Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/5527/.
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Polymer electrolyte membrane fuel cells (PEMFCs) are envisioned to replace internal combustion engines (ICEs) as vehicle power sources and to compete with conventional technologies in backup power systems, residential combined heat and power (CHP) devices and consumer electronics. However, the commercial viability is still hindered due to the cost and durability that are significantly related to the precious metal catalysts used in these cells. In the current work, two different methods towards reducing the precious metal content by the use of transition metal (Cr) with Pt as electrocatalysts for PEMFCs are reported. The commercial Pt/C catalysts layer consists of three components i.e. Pt, carbon support and Nafion ionomer. The Nafion ionomer binder does not penetrate through the microporous carbon support and thus limits the triple phase boundary region (catalytic reaction takes place at triple phase boundary), which in turn leaves a significant amount of Pt being inactive or not utilised. In the first part of this work, Nafion- stabilised Pt-Cr alloys are synthesised using a novel wet chemical synthesis. The aim of this work is to improve the triple phase boundary region with the introduction of Nafion during the synthesis and alloying with Cr that can enhance the catalytic activity. Thus, in turn improving the utilisation of the catalyst and also reducing the amount of Pt loading.
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Larsson, Beatrice. "Kommunikationssvårigheter inom autismspektrumtillstånd : En fallstudie om användningen av det alternativa kommunikationsverktyget PECS." Thesis, Uppsala universitet, Institutionen för pedagogik, didaktik och utbildningsstudier, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-238506.
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Syftet med denna studie är att undersöka användningen av det alternativa kommunikationsverktyget PECS (Picture Exchange Communication System), som är vanligt förekommande hos personer inom autismspektrumtillstånd (ASD). Hos människor inom ASD är det vanligt med kommunikationssvårigheter samt utpräglade beteendeproblem. Genom intervjuer med skola, habilitering och boende har PECS studerats utifrån olika aspekter. Hur går inlärningen till? Hur används verktyget i det dagliga livet? Vilka för- och nackdelar upplevs vid arbete med PECS? Resultatet visar att PECS är ett kommunikationsverktyg med hög evidens men att det finns delade åsikter kring vissa delar. Studien pekar på betydelsen av kunskap och förståelse för att barn inom ASD behöver ges möjlighet att utveckla en fungerande kommunikation och att kommunikationsverktyget PECS kan bidra till detta.
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Cruz-Manzo, Samuel. "Electrochemical mechanisms of the impedance spectrum in polymer electrolyte fuel cells." Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/12316.
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Electrochemical impedance spectroscopy (EIS) is a powerful technique that can be applied in-situ to deconvolute the various loss mechanisms in the polymer electrolyte fuel cell (PEFC) that occur at different rates. The frequency response of a PEFC that results from EIS is in essence characterised by energy dissipating and energy storing elements of the cell. It can be represented by an equivalent circuit that is composed of resistors and capacitors respectively. By understanding the arrangement and magnitude of the electrical components in the equivalent electrical circuit, it is possible to generate a deeper understanding of how and where the electrical energy that is generated due to the redox reaction is being dissipated and retained within the real physical system. Although the use of equivalent circuits is often an adequate approach, some electrochemical processes are not adequately described by electrical components. In which case, it is necessary to adopt a more rigorous approach of describing processes through the use of differential equations to describe the physics of the electrochemical system at the frequency domain. Studies in the literature have attempted to construct mathematical models to describe the impedance response of the cathode catalyst layer (CCL) based on conservation equations describing the electrochemical and diffusion processes. However this has resulted in a complicated mathematical analysis which in turn results in complicated solutions. The resulting equations cannot be easily validated against real-world EIS measurements and only analytical results have been reported. In this thesis a mathematical model to describe the impedance response of the CCL has been developed. This model is derived from fundamental electrochemical theory describing the physics of the CCL. The mathematical treatment is simplified by taking into account some considerations based on the EIS theory. The resulting model can be easily applied to real-world EIS measurements of PEFCs and presents parameters commonly known in the electrochemical area. The scientific contribution of this doctoral thesis is mainly divided in two sections: Modelling and Application. The first step of the modelling section develops an equation describing charge conservation in the CCL and together with Ohm s Law equation accounting for ionic conduction, predicts the impedance response of the CCL at low currents. The second step includes the change of oxygen concentration during the oxygen reduction reaction (ORR) into the equation accounting for CCL low current operation. The study of mass transport in the CCL is very complex; the literature has treated it with simplifications and approximations. The finite diffusion distance for oxygen to reach the reaction sites in the CCL forms a complicated network of multi-phase parallel and serial paths and can change in dimension at different operating conditions (flooding, drying). In the mathematical treatment of this doctoral thesis the finite diffusion distance and surface concentration of oxygen in the CCL are considered to be independent of the thickness of the CCL. EIS reflects only bulk measurements based on the total CCL thickness. Even though this results in an over-simplification for the oxygen diffusion in the total CCL, this approach simplifies the mathematical treatment to predict the impedance response of the CCL at high current operation, and as result it can be successfully validated against real-world EIS measurements. In the application section the model is applied with real-world EIS measurements of PEFCs. First the model is applied with EIS measurements presenting inductive effects at high frequencies. The model reveals mechanisms masked at high frequencies of the impedance spectrum by inductance effects. The results demonstrate that the practice of using the real part of the Nyquist plot where the imaginary part is equal to zero to quantify the ohmic resistance in PEFCs can be subject to an erroneous interpretation due to inductive effects at high frequencies. Secondly the model is applied to cathode impedance data obtained through a three-electrode configuration in the measurement system and gives an insight into the mechanisms represented at low frequencies of the impedance complex-plot. The model predicts that the low frequency semicircle in PEFC measurements is attributed to low equilibrium oxygen concentration in the CCL-gas diffusion layer (GDL) interface and low diffusivity of oxygen through the CCL. In addition the model is applied with simultaneous EIS measurements in an Open-Cathode PEFC stack. The factors that limit the performance of the PEFC stack are evaluated with simultaneous EIS measurements and the model. The results show that the change in impedance response of individual cells within the stack is attributed to oxygen limitations, degradation in membrane electrode assemblies (MEAs) and temperature distribution. This EIS knowledge enables an assessment of the state of health in operational fuel cell stacks. In the last section of the application section, the mathematical model translated in the time domain via reverse Laplace Transform predicts the current distribution through the CCL. This provides information to improve the performance of the CCL as well as determine the uptake of product water in the membrane. Finally the conclusions and future work are presented. This doctoral thesis has established a backbone understanding of how the electrochemical and diffusion mechanisms relate to the electrochemical impedance spectra of PEFCs. The goal of a future work is to develop this EIS knowledge into a real-time EIS system for non-intrusive diagnostics of degradation in operational PEFCs. This implies a modification of the model to consider oxygen transport through the CCL thickness as part of a multi-species mixture using mass transport theory including concentrated solution theory to fuel cell engineering.
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ZHENG, WEIBO. "Pore-Scale Simulation of Cathode Catalyst Layers in Proton Exchange Membrane Fuel Cells (PEMFCs)." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555436163992345.
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Alharbi, Helal. "Synthesis of Diazonium N-(Perfluoroalkyl) Benzenesulfonimide Polymers for Proton Exchange Membrane Fuel Cells (PEMFCs)." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/etd/3601.
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The objective of the research is to synthesize the diazonium N-(perfluoroalkyl) benzenesulfonimide (PFSI)zwitterionicpolymers as electrolytes in polymerelectrolyte membrane (PEM) fuel cells. The proposed diazoniumPFSI zwitterionic polymer (I) is expected to enhance the thermal and chemical stability, increase the proton conductivity of electrolytes, and improve the catalyst efficiency for PEM fuel cells. Synthesis of the perfluorobenzoyl peroxide initiator, homopolymerization of perfluoro (3-oxapent-4-ene) sulfonyl fluoride,coupling reaction with4-sulfamonylacetanilide, couplingreaction with 4-nitrobenzene sulfonyl amide, n-deacetylation reaction, and diazotization reactionhave been carried outsuccessfully in the lab. The intermediate chemicals are characterized by GC-MS, IR, NMR, and GPC spectroscopies.
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Chnani, Moussa. "Modélisation Macroscopique de piles PEFC et SOFC pour l'étude de leur couplage." Phd thesis, Université de Franche-Comté, 2008. http://tel.archives-ouvertes.fr/tel-00422119.
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L'ambition du projet Européen « FELICITAS » est le développement de générateurs piles à combustible performants pour les applications transport de type ferroviaire, routier lourd et maritime. Les travaux présentés concernent plus particulièrement l'évaluation d'une hybridation de sources originale où sont couplées en série une pile haute température de type oxyde solide (SOFC) alimentée en diesel et une pile basse température de type électrolyte polymère (PEFC). La SOFC participe ainsi à la fourniture de puissance électrique et contribue également au procédé de purification du combustible destiné à la PEFC en oxydant une fraction du monoxyde de carbone.Une approche de modélisation macroscopique a été développée. La complexité d'une pile à combustible réside notamment dans la prise en compte de son caractère multiphysique : elle est le siège des phénomènes électrochimique, fluidiques et thermiques. Cette difficulté a été surmontée en utilisant une analogie avec un circuit électrique équivalent pour unifier ses trois aspects, implanter et coupler ces sous-modèles dans un logiciel unique sous Matlab/Simulink™.
Un modèle de pile SOFC est proposé, appliquant le principe d'analogie électrique pour les circuits anodiques et cathodiques ainsi qu'une méthode nodale pour le comportement thermique. Le combustible considéré est un mélange d'hydrogène, d'azote, de monoxyde de carbone, de dioxyde de carbone et de vapeur d'eau, dont la composition est proche de celle obtenue à la sortie d'un reformeur. Un banc d'essai spécifique a été conçu et réalisé pour le test de petits empilements afin de valider le modèle. Deux types de conception de stack ont été étudiés : une technologie à combustion libre du gaz anodique dans le fluide et une technologie à collecteur de gaz d'échappement anodique.
Un modèle de pile PEFC isotherme a également été développé sur le même principe. La validation expérimentale a été faite sur un banc disponible au laboratoire. Une bibliothèque des éléments fluidique d'un générateur à pile à combustible a été enrichie (électrovanne, régulateur de débit, détendeur...) notamment par un modèle simplifié de compresseur d'air.
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Frenell, Staaf Cecilia, and Edwina Matsson. "Privata skogsägares syn på ansvarsamt behovet av kunskap ochinformation om PEFC- certifieringen." Thesis, Linnéuniversitetet, Institutionen för skog och träteknik (SOT), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-65304.
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Skogsägare har möjlighet att certifiera sin skogsfastighet i enlighet med FSC och/eller PEFC. Flera av de skogsägare som certifierar sin fastighet känner dock inte till PEFC:s krav. Studiens syfte var undersöka synen på ansvar och behovet av kunskap och information om PEFC. Endast 66 % av skogsägarna ansåg att det var de själva som stod ytterst ansvarig för sin skogsfastighet och lika stor andel ansåg att informationen de fått om PEFC varit tillräcklig. Drygt hälften av skogsägarna ansåg sig ha tillräcklig kunskap om PEFC. Studien visade att flera olika faktorer spelar in på skogsägarnas syn på ansvar och behovet av kunskap och information.
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Ökshei, Jorunn, and Hannah Eriksson. "Certifieringens betydelse för naturvärden i skogen." Thesis, Linnéuniversitetet, Institutionen för skog och träteknik (SOT), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-85925.
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En viktig målsättning i den svenska skogspolitiken är att skogsbruket ska bedrivas på ett hållbart sätt och i Skogsvårdslagen är produktionsmålen och miljömålen jämställda. Skogsägare kan utöver detta åta sig att certifiera sin fastighet, antingen genom FSC eller PEFC. Certifiering är ett marknadsdrivet, frivilligt åtagande och handlar om att ta ett större ansvar för miljö och natur än vad Skogsvårdslagen kräver. Syftet med denna studie är att jämföra förekomst av naturvärden på certifierade fastigheter och icke-certifierade fastigheter genom fältinventering av utvalda kriterier. Kriterierna valdes utifrån mätbara och synliga indikatorer på naturvärden och utifrån faktorer som speglar variationsrikedom, hänsyn, kontinuitet, flora-och faunaobjekt och återväxt. I denna studie har vi arbetat fram en funktionell inventeringsmall i syfte att kartlägga naturvärden på fastighetsnivå. En slutsats från inventeringen var att naturens egna förutsättningar är en viktig faktor för förekomsten av naturvärden i högre grad än om fastigheten är certifierad eller inte.
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Ali, Emad Mohammed. "The Effectiveness of Combining Tangible Symbols with the Picture Exchange Communication System to Teach Requesting Skills to Children with Multiple Disabilities including Visual Impairment." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/195459.
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The Picture Exchange Communication System (PECS) is an augmentative and alternative communication program (Frost & Bondy, 2002). Although PECS has been effectively used to teach functional requesting skills for children with autism, mental retardation, visual impairment, and physical disabilities (e.g., Anderson, Moore, & Bourne, 2007; Chambers & Rehfeldt, 2003), there are limited studies examining the effectiveness of PECS to teach requesting skills for children with multiple disabilities including visual impairment (Lund & Troha, 2008).This study explored the effectiveness of combining tangible symbols and other adaptations with PECS to teach requesting skills to students with multiple disabilities. Specifically, the participants were four students with multiple disabilities including visual impairment who also had many challenges in communication skills. The research design was the multiple probe design across subjects, a variation of a multiple baseline design. A notable benefit to this design is that there was no need to collect continuous recordings of baseline measures, because a strong a priori assumption of stability and the possibility of causing strong participant reactions existed before introducing the intervention. Instead, the researcher made periodic recordings of baseline levels to insure no significant changes have occurred before introducing the intervention.The study included four parts: (a) the assessment of reinforcers, (b) baseline, (c) the implementation of the intervention, which was teaching the three PECS phases and conducting generalization sessions, and (d) the maintenance condition. Three important research questions were posed:1. Can students with multiple disabilities including visual impairment learn to make requests for preferred items using adapted PECS materials and procedures?2. Can students with multiple disabilities including visual impairment generalize requesting skills for preferred items using adapted PECS from training rooms to classrooms?3. Can students with multiple disabilities including visual impairment maintain requesting skills after training?The results indicated that all four participants learned requesting skills using adapted PECS, generalized the newly acquired skills to their classrooms, and maintained the requesting skills after training. Results of this study provided preliminary evidence that PECS with adaptations could be used effectively to teach requesting skills for students with multiple disabilities including visual impairment.
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Arena, Francesco [Verfasser], and Rolf [Akademischer Betreuer] Hempelmann. "Cross-linked sPEEK and its application for high temperature PEMFCs / Francesco Arena. Betreuer: Rolf Hempelmann." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2016. http://d-nb.info/1105472000/34.
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Rodrigues, Viviane. "Efeitos do PECS associado ao video modeling em crianças com síndrome de Down." Universidade Federal de São Carlos, 2015. https://repositorio.ufscar.br/handle/ufscar/3183.
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Previous issue date: 2015-02-24Financiadora de Estudos e Projetos
The Augmentative and Aumentative Communication (AAC) is an area of assistive technology that seeks to facilitate the participation of people in different communicative contexts. There is a variety of techniques and methods one of them Picture Exchange Communication (PECS) that proposes to develop communication skills within the social context. Associated with the implementation of PECS, some research has shown benefits of using Video Modeling (VM) that consists a teaching technique that search the development of academic, social, communication and daily leaving skills for individuals of various disabilities. The objective of this study was to apply and analyze the effects of PECS associated with the VM on the development of communication skills of children with Down syndrome. To this end, we selected three participants in a special school in one city in the state of São Paulo, aged between nine and 12 who were diagnosed as Down syndrome and complex communication needs. The following instruments were used in this study: Assessment of Communication Skills was used to evaluate functional communication skills the child; Protocol for Communication Skills Assessment in a school environment with the objective to identify the communication skills of the student in the school environment from the perception of teachers; Vocabulary selection spread sheet with the objective to identify reinforcing objects; Record Sheet that informed participants' performance during the intervention process; Vocabulary sheet monitored the vocabulary of the participants during the intervention; Chart Qualitative Performance was used as a field diary in order to record observations during the intervention process and the Social Validity of questionnaire with the objective to evaluate the perceptions of parents and teachers of the participants about the intervention. In order to verify the effects of the intervention it used Multiple Baseline Design cross subjects including three phases: baseline, intervention, and maintenance, in which the PECS associated with the VM was the independent variable and communication skills constituted the dependent variable. Data were analyzed considering some aspects such as the participant's performance, monitoring vocabulary, level of independence in the baseline, intervention and maintenance steps. The results showed that participants' performance was satisfactory both in respect of each phase and with respect to all the learning process intervention. The level of independence remained above average throughout the training for the three participants, in other words, they understood what they must do in each session of each phase without the aid of the communication partner or physical stimulator. There was an increase in the vocabulary of the three participants, although each of them with his own specificities and development of language, it is noted that the use of the pictures served as a support for the increase in this vocabulary words and phrases formulations through both figures as through speech. Thus, the present study showed a possibility of intervention that favored the participants with Down syndrome, demonstrating that the PECS associated with the VM promoted the development of communication skills, both in speech production as in the use of the figure as a form of communication.
A Comunicação Suplementar e Alternativa (CSA) é uma área da tecnologia assistiva que busca facilitar a participação das pessoas nos vários contextos comunicativos. Há uma variedade de técnicas e métodos em CSA uma delas é o Sistema de Comunicação por Troca de Figuras (PECS), que tem como propósito aumentar as habilidades de comunicação dentro do contexto social. Associado à aplicação do PECS, algumas pesquisas têm demonstrado benefícios do uso do Video Modeling (VM) que consiste em uma técnica de ensino voltada às habilidades de comunicação social, vida diária e desempenho acadêmico para indivíduos das mais variadas deficiências. A presente pesquisa teve por objetivo aplicar e analisar os efeitos do PECS associado ao VM em relação ao desenvolvimento das habilidades de comunicação em crianças com síndrome de Down. Para tanto, foram selecionados três participantes de uma escola especial de um município do interior paulista, com idades variando entre nove e 12 anos que apresentavam diagnóstico de síndrome de Down, além de necessidades complexas de comunicação. Para a coleta de dados foram utilizados os seguintes instrumentos: Avaliação das Habilidades de Comunicação que teve por finalidade avaliar as competências de comunicação funcional da criança; Protocolo para a Avaliação de Habilidades Comunicativas em ambiente escolar que objetivou identificar as habilidades comunicativas do aluno em ambiente escolar a partir da percepção dos professores; Planilha de seleção de vocabulário que objetivou identificar os itens reforçadores; Folha de Registro que informou o desempenho dos participantes durante o processo de intervenção; Folha de Vocabulário monitorou o vocabulário dos participantes durante a intervenção; Quadro Qualitativo do Desempenho foi utilizado como um diário de campo com a finalidade de registrar observações durante o processo de intervenção e o Questionário de Validade Social que teve por finalidade avaliar a percepção dos pais e professores dos participantes quanto à intervenção. Para tanto, empregou-se o delineamento experimental de linha de base múltipla cruzando com sujeitos (linha de base, intervenção e manutenção), sendo o PECS associado ao VM a variável independente e as habilidades de comunicação se constituíram na variável dependente. Os dados foram analisados considerando alguns aspectos como o desempenho dos participantes, monitoramento do vocabulário e nível de independência nas etapas de linha de base, intervenção e manutenção. Os resultados indicaram que o desempenho dos participantes foi satisfatório, tanto em relação a cada fase, como em relação à aprendizagem de todo o processo de intervenção. O nível de independência se manteve acima da média durante todo o treinamento para os três participantes, ou seja, conseguiram compreender o que precisavam fazer em cada sessão de cada fase sem o auxílio do parceiro de comunicação ou do estimulador físico. Observou-se um aumento no vocabulário dos três participantes, embora cada qual com suas especificidades e desenvolvimento de linguagem própria, foi possível perceber que o uso da figura serviu de apoio para o aumento de vocabulário presente nas formulações de palavras e frases tanto por meio das figuras como por meio da fala. Dessa forma, o presente estudo apresentou uma possibilidade de intervenção que favoreceu os participantes com síndrome de Down, demonstrando que o PECS associado ao VM promoveu o desenvolvimento das habilidades de comunicação, tanto na produção da fala como no uso da figura como forma de comunicação.
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Sonne, Lehnberg Ida. "Privata skogsägares uppfattning om FSC- och PEFC-certifiering : att bli och vara certifierad." Thesis, Linnéuniversitetet, Institutionen för skog och träteknik (SOT), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-76666.
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Syftet med studien var att beskriva och analysera hur Sydveds certifieringsprocess upplevs av företagets virkesleverantörer. Studien genomfördes som en enkätundersökning via post och e-post. De frågeställningar som utgjorde stommen av arbetet handlade huvudsakligen om upplevelsen kring certifieringsprocessen, virkesleverantörernas kunskap om certifiering, motiv till certifiering och hur dessa påverkar upplevelsen av certifieringsprocessen. Fokus låg även på huruvida den geografiska spridningen hade någon betydelse för upplevelsen liksom om virkesleverantörerna upplevde ett behov av en förändring i certifieringsprocessen. Sammanfattningsvis visade resultaten främst på en förbättringspotential gällande återkoppling och kunskap. Det som Sydved rekommenderas att utveckla är olika delar av certifieringsprocessen där tyngdpunkten bör ligga på att få ett enhetligt sätt att jobba på inom organisationen. Hela certifieringsprocessen, från introduktion till revision och återkoppling bör ha tydliga riktlinjer, då kedjan inte är starkare än sin svagaste länk.
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Barrett, Shaun Michael. "The Effects of Video Modeling on the Adult Implementation of PECS Phase 1A." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1502878106722814.
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Cranmer, Elizabeth. "The Effects of PECS Training on Symbolic Matching Skills in Learners with Autism." Thesis, University of North Texas, 2009. https://digital.library.unt.edu/ark:/67531/metadc10997/.
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This study evaluated whether picture exchange communication system (PECS) training would result in the development of conditional relations among corresponding pictures, objects (reinforcers) and spoken words used in PECS training with learners with developmental disabilities. Three participants with autism and mental retardation were trained to use PECS. Match-to-sample procedures were used to assess all possible conditional relations among stimuli before, during, and after PECS training. None of the three participants in this study acquired conditional discriminations involving the pictures, reinforcers, and spoken words used in their PECS training.
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Cranmer, Elizabeth Glenn Sigrid S. "The effects of PECS training on symbolic matching skills in learners with autism." [Denton, Tex.] : University of North Texas, 2009. http://digital.library.unt.edu/permalink/meta-dc-10997.
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Boudloche, Lloyd JR. "A Comparison of Manual Signing and PECS Within a Functional Communication Training Context." Thesis, NSUWorks, 2016. https://nsuworks.nova.edu/fse_etd/105.
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This applied dissertation study was designed to inform and advance knowledge regarding research in the area of the effectiveness of functional communication training (FCT) in reducing challenging behaviors among individuals with autism spectrum disorder (ASD) who were nonverbal, by using a quantitative single subject approach. The researcher specifically focused on determining which modality, Picture Exchange Communication System (PECS) or manual sign language, would be the most effective as a replacement behavior to bring about a reduction in challenging behaviors. Previous researchers in the field of FCT did not address this area, thus leaving a gap in the research.
The participants for the study were three children with ASD between the ages of 4 and 6. Prior to the start of the study, multiple assessments were administered to assess the function of challenging behaviors, level of functioning, imitation skills, and preferences.
The intervention phases consisted of randomly alternating between a session of PECS and manual sign daily with each session consisting of 10 trials. Baseline data was collected to assess preexisting skill level to mand for items. The intervention trials continued until the participants reached mastery level in either modality. Results demonstrated that only PECS was effective for both the participants who completed the study, and for the participant who mastered both manual signing and PECS, PECS had a quicker acquisition rate. Implications from the findings suggest that FCT is an effective intervention in reducing challenging behaviors, and that PECS might be more effective for quick reductions of challenging behaviors. The study is a valuable addition to the current FCT research as it aligns with and extends findings from previous research.
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Slavík, Jiří. "Modelování umělého života." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2007. http://www.nusl.cz/ntk/nusl-412757.
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Artificial life modelling is an extensive subject to exert effort in one piece of work such as this work. For that reason this work is limited to keep the base line of modelling of human behavior. Presented work deal with a creation of an artificial agent whose human-like behavior is implemented according to the PECS reference model. Specification of the PECS reference model is implemented in Java to build a simulation of artificial human being in some environment. Modeled human being has been assigned to imitate human activities, react adequately to sensed events from the environment and change the environment to achieve its goals. Modeled human being is a behavior controled entity acting according to its current role.
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Desmond, Catherine Sarah. "Generalisation of the Picture Exchange Communication System (PECS) across transfer facilitated and non-facilitated settings." Thesis, University of Canterbury. Psychology, 2012. http://hdl.handle.net/10092/9286.
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The purpose of this study was to investigate the extent to which PECS would generalise from the training setting to other familiar settings as a function of properties of the settings. It was predicted that PECS would generalise better to the setting where PECS use facilitated was by having the same communicative partners and items available. Three preschool children all with a diagnosis of Autism Spectrum Disorder (ASD) were trained to use the Picture Exchange Communication System (PECS) to a minimum proficiency level of Phase 3. The experiment employed an ABA single case design with multiple target measures, replicated across participants, acknowledging that observations in the first baseline would be zero. Transfer of PECS across settings varied for each participant. One participant generalised PECS to the facilitated environment more than the non-facilitated environment as predicted. Another participant transferred PECS better to the non-facilitated environment compared to the facilitated environment contrary to the research prediction. The final participant did not generalise PECS to either environment, switching to functional verbal
communication instead.
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Nilsson, Lena. "PECS som samtalsstöd vid autism : En interventionsstudie med införande av en kommunikationskarta anpassad för pratstunder." Thesis, Uppsala universitet, Logopedi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-150410.
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Syftet med denna studie var att undersöka hur en för situationen anpassad kommunikationskarta, en pratkarta, kan möjliggöra samtal mellan en 11-årig pojke med autism och utvecklingsstörning och hans mamma när de samtalar om en händelse som inte händer nu. Erik har inget fungerande tal och är beroende av Alternativ och Kompletterande Kommunikation (AKK). Han har sedan förskoletiden en pärm med löstagbara bilder (PECS), som han använder för att uttrycka sina behov och intentioner. I studien undersöktes hur interaktionen mellan Erik och hans mamma Maria organiserades sekventiellt. Analysen visade att en kommunikationskarta, en pratkarta med bilder anpassade för samtalet, var en viktig gemensam resurs för både Maria och Erik för att initiera, utveckla och avsluta pratstunden. Analysen baserades på videoinspelat material i hemmet, inspelat av Maria, där deltagarna pratade om den förestående julhelgen. Samtalsanalys (Conversation Analysis) användes som analysmetod. Det visade sig att deltagarna orienterar mot tre huvudsakliga faser i det kommunikativa projektet att etablera samtal om julen:prefas, huvudfas och postfas. Pratkartan var en viktig kommunikativ resurs för både Maria och Erik, vilken de orienterade mot i alla delar av samtalet. Prefasen bestod av de handlingar som leder fram till att Erik använder PECS-bilder för att involvera sig i samtalet. I prefasen var pratkartan helt avgörande för att Erik skulle komma igång och pecsa. I huvudfasen, den fas där Erik använder PECS-bilder för att samtala om julen, utvecklade Maria och Erik gemensamt olika ämnesaspekter av samtalet. Maria upprepade och utvidgade utifrån Eriks pecsyttranden. Hon gav också värderande bidrag och föreslog nya perspektiv på det pågående ämnet. Erik upprepade, byggde ut och överlappade Marias bidrag, men han kunde också aktivt bibehålla koherens i episoden och följde inte alltid Marias utvidgning eller förslag på nya ämnesaspekter. I postfasen avslutade deltagarna pratstunden och talet om julen. Erik bidrog aktivt till avslutandet genom att plocka ihop pratkartorna. Maria bekräftade både verbalt och genom att använda SLUTA-PRATA-bilden att pratstunden är avslutad. Förslag ges på framtida praktikbaserade studier som kan bidra till evidensbaserad praktik.
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Evaristo, Fabiana Lacerda. "Formação de aplicadores e interlocutores na utilização do PECS-Adaptado para crianças/adolescentes com autismo." Universidade Federal de São Carlos, 2016. https://repositorio.ufscar.br/handle/ufscar/7475.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Communication is one of the most important factors related to the quality of life of people with the diagnosis of autism, which can be absent or dysfunctional, with or without speech. Due to the importance of communication for humans to establish social exchanges, this study aims to evaluate the efficacy of an applicants and interlocutors training program for use of PECS-Adaptado in children /adolescents with autism spectrum disorder. The participants were three students not oralized and/or no functional speech. The criterion for the selection of participants in this study was based on the searching for students not oralized and/or no functional speech who presented diagnosis of autism spectrum disorder and does not presented visual and/or hearing impairment, in a midsize city located within the state of São Paulo. The classroom was attended by the teacher (PP1) of the participating students (PA1 and PA2) and the mother (PM3) of one of the participating students, who were qualified as interlocutors through teaching procedures of PECS-Adaptado program. It was used intermittently design of multiple baseline between participants, in which the subject acts as his own control. Family members of participants provide data for research according to the semi-structured initial interview guide and the list of participant’s interests. At the end of the sessions with the phase 3, the PA1 and PA2’s relatives were invited to follow the activities with their children at school, in order to also becoming immediate interlocutors. PM3 attended all sessions and another relative (father PA3) monitored the activities from stage 3. The interventions were conducted in a classroom of a special education school with the PA1 and PA2 by interlocutor PP1, and the house of PA3 by interlocutor PM3. The records protocols with PECS-Adaptado’s phases were used to record the performance of the participants. It was also used a record protocol for the interlocutors in order to recognize their performance through the opportunities offered to the participants. The results indicate that, after the application of interlocutors training program with the teacher and with the mother, the participating students presented satisfactory development of communication by exchange of figures. During the survey, participating students increased their communication skills, according to their needs and their desires through the interference of the interlocutors, who had an important role in the achievement of the program's effectiveness. The applicants and interlocutors, in addition of being capacitated, also understood the importance of using the alternative communication program for teaching and learning.
A comunicação tem sido um dos fatores mais importantes apontados no que diz respeito à qualidade de vida de pessoas com o diagnóstico de autismo, muitas vezes, nesses casos, podendo ser inexistente ou disfuncional, com ou sem fala. Diante da importância da comunicação para o ser humano estabelecer trocas sociais, esta pesquisa teve como objetivo avaliar a eficácia de um programa de formação de aplicadores e interlocutores para utilização do PECS-Adaptado em crianças/adolescentes com transtorno do espectro do autismo. Participaram da pesquisa três alunos não oralizados e/ou sem fala funcional. O critério para a seleção dos participantes baseou-se na procura de alunos não oralizados e/ou sem fala funcional, com diagnóstico de transtorno do espectro do autismo e ausência de deficiência visual e/ou auditiva, em um município de médio porte localizado no interior do estado de São Paulo. Participaram, também, a professora da sala de aula (PP1) dos participantes alunos (PA1 e PA2) e a mãe (PM3) de um dos participantes alunos, as quais foram capacitadas como aplicadoras e interlocutoras por meio dos procedimentos de ensino do programa PECS-Adaptado. Foi utilizado o delineamento intermitente de linha de base múltipla entre participantes, em que o sujeito atua como o seu próprio controle. Os familiares dos participantes forneceram dados necessários para o planejamento das intervenções, de acordo com o roteiro de entrevista semiestruturado inicial e com a lista de interesses dos participantes. Ao final das sessões, com a fase 3, os familiares de PA1 e PA2 foram convidados a acompanhar as atividades com os seus filhos na escola, a fim de se tornarem também interlocutores imediatos. A PM3 participou de todas as sessões e outro familiar (pai de PA3) acompanhou as atividades a partir da fase 3. As intervenções foram realizadas em uma sala de aula de uma escola de Educação Especial com o PA1 e PA2 pela interlocutora PP1, e na residência de PA3, pela interlocutora PM3. Os protocolos de registros com as fases do PECS-Adaptado foram usados para registrar o desempenho dos participantes. Também foi utilizado um protocolo de registro para as aplicadoras e interlocutoras a fim de reconhecer seu desempenho por meio das oportunidades oferecidas aos participantes. Os resultados alcançados apontam que, a partir da aplicação do programa de formação de interlocutores com a professora e com a mãe, os participantes alunos apresentaram desenvolvimento satisfatório de comunicação por troca de figuras. Durante a pesquisa, os participantes alunos aumentaram suas habilidades comunicativas de acordo com as suas necessidades e seus desejos, por meio da ação das aplicadoras e interlocutoras, que tiverem interferência durante todo o programa, garantindo sua eficácia. As aplicadoras e interlocutoras além de terem sido capacitadas, também compreenderam a importância do uso do programa de comunicação alternativa para o processo de ensino e aprendizagem.
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Farrer, Amy. "Do children with autism use the Picture Exchange Communication System (PECS) to make spontaneous requests?" Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/171963/.
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This review examines the research on the Picture Exchange Communication System (PECS), which has become a popular communication strategy for children with autism and other communication disorders. A growing body of research has shown that the system is a promising mode of communication. There is, however, a paucity of research that examines the conditions under which the PECS is used, specifically whether children use the PECS to make spontaneous requests. A lack of agreement currently exists over the definition of the term ‘spontaneity’ and so researchers of the PECS who do report instances of spontaneity may be basing the judgment on different patterns of behaviour. Skinner’s (1957) analysis of verbal behaviour and the continuum model of spontaneity (Carter, 2002,2003a; Carter & Hotchkis, 2002; Chiang & Carter, 2008) can be used to understand the development of self-initiated requesting behaviour. Both frameworks state that requests can only be considered as fully spontaneous if they occur without prompts from another person and when the desired item is not in sight. There is a lack of research that examines whether children are able to use the PECS to make requests under these conditions. Furthermore, this literature review shows that some children may be unable to use the PECS to request items not in sight because of the teaching conditions used and/or because the reinforcement practices of the community may be inefficient, and, therefore, ways of promoting spontaneity are considered.
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Lavigne, Olivier. "Caractérisation des films passifs pour la définition de nouveaux matériaux : application aux plaques bipolaires métalliques des systèmes PEMFCs." Lyon, INSA, 2009. http://theses.insa-lyon.fr/publication/2009ISAL0047/these.pdf.
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L’objectif de ce travail est de déterminer des solutions matériaux pour la réalisation de plaques bipolaires embouties, répondant aux spécifications techniques d’une utilisation en milieu pile à combustible de type PEMFC. Sur la base des propriétés d’usage, l’acier 316L a été proposé comme matériau de référence. Pour autant la conductivité de sa couche passive formée en surface reste faible, et fait ainsi chuter les performances de la pile. La modification de la surface de ce matériau est donc indispensable. La première voie développée dans ce travail a été d’élaborer un dépôt par PVD de type CrN sur cet acier. La structure, ainsi que les propriétés de résistance à la corrosion et de conductivité des couches passives formées sur ces matériaux, dépendent de la teneur en azote du revêtement et de la nature du substrat. La caractérisation ex-situ du revêtement dit ‘haut azote’ élaboré sur acier, montre que celui-ci répond à la problématique posée. Toutefois, ces matériaux induisent un coût supplémentaire dû au process et nécessitent une bonne tenue à l’emboutissage. La deuxième approche de modification de surface a donc été la fonctionnalisation de la couche passive existante sur l’acier 316L. L’ajout par voie électrochimique de Ce dans les couches d’oxydes à permis d’en modifier les propriétés. Ce traitement préserve la résistance à la corrosion du matériau, tout en diminuant la valeur de la résistance de contact interfaciale de 78%. Sur la base du traitement précédent, il a pu être proposé de nouvelles nuances d’aciers intégrant quelques % massique d’éléments dopants (Ce, Ta) dans le but de ‘fonctionnaliser’ le film passif. Les caractérisations physico-chimiques de ces nuances ont montré l’intérêt de tels alliages pour l’application visée. En effet, tout en maintenant de bonnes propriétés de résistance à la corrosion, une diminution importante des valeurs de résistances de contact interfaciale est observée. Bien que certaines spécifications n’atteignent pas encore les valeurs souhaitées, ce travail valide une démarche originale de choix de matériauxThe aim of this work is the determination of materials solutions for stamped bipolar plates used in PEMFCs systems. The 316L SS was chosen as the reference material. However, the conductivity of its passive layer remains low, and leads to a diminution of the fuel cell performances. Surface modifications of this material are thus essential. The first way developed in this work was the physical vapour deposition of chromium nitrides onto the stainless steel. Structure, as well as corrosion resistance and physical properties, of formed passive layers onto these samples, depend on the nitrogen content of the coating and the nature of the substrate. Ex-situ characterisations of ‘high nitrogen’ coating on 316L suggest its suitability for use in the bipolar plates of PEMFCs. However, the coated materials induce supplementary costs (process) and need good mechanical properties for stamping. The second way of surface modification was thus the modification of the existent passive layer formed onto the 316L. Cerium was added within the oxide layer by an electrochemical treatment. This treatment preserves the corrosion resistance of the material, and allows a decrease of the interfacial contact resistance value of 78%. Based on the above treatment, new steels compositions was proposed, including some % in weight of doping elements (Ce, Ta) in order to modify the passive film. Physical and chemical characterisations of these new materials showed their suitability for the targeted application. Indeed, these alloys display good corrosion resistance properties, as well as a great decrease of the interfacial contact resistance. In spite of the fact that these values do not reach the wanted goal, this work validates an original method of material choice
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Ben, Chaabane Delia B. "The effects of parent implemented training on improvisation of mands by children with autism." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1172144721.
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Reum, Mathias. "Sub-millimeter resolved measurement of current density and membrane resistance in polymer electrolyte fuel cells (PEFC) /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17979.
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Walter, Catia Crivelenti de Figueiredo. "Os efeitos da adaptação do PECS associada ao Curriculum funcional natural em pessoas com autismo infantil." Universidade Federal de São Carlos, 2000. https://repositorio.ufscar.br/handle/ufscar/3043.
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Communication disorders in persons diagnosed with autism, generally are severe and bring difficulties to their interpersonal relationships, putting them apart, being not comprehended by the majority of other people. The main objective of this study was to evaluate the effects of the adaptation of the Picture Exchange Communication System (PECS) applied in the context of a natural functional curriculum (adapted PECS) in the communication of persons diagnosed as autistic, who do not presented oral language and/or functions speech at the beginning of the study. As a secondary objective, the study had the intention to verify if the adapted PECS would help the participants to begin to use of speech. The study was conducted at Centro Ann Sullivan do Brasil (CASB), located in Ribeirão Preto City São Paulo State. In order to verify the effects of the intervention, an AB simple subject research design was applied and replicated within four boys with ages varying from 5 to 8 years old, diagnosed as autistic. The study involved two phases: baseline and intervention. In order to train the 5 phases of the adapted PECS, the PCS (Picture Communication System) pictures was used. The training and data collection sessions were held during 2 years. The results showed that all participants presented changes in their communicative behavior and acquired an expressive vocabulary in some words, some sounds and in the use of pictures, that varied from 25 to 61, all being used with communicative function. The obtained data suggests that the use of pictures with interaction and solicitation objective of something very much desired, seems to contribute to the emission of speech, sounds and gestures, used with communicative function by the participants. However, other studies must be encouraged, as well as the adapted PECS extension to persons with different diagnoses, who are able to benefit from any alternative communication system. The study concludes, since the PECS communication system has a basic element the interested picture exchanging by the participants through an interactive action, could contribute, in the future, to the inclusion process, not only at school environment, but also to home and community
Os distúrbios da comunicação presentes em pessoas com diagnóstico de Autismo Infantil geralmente são graves e dificultam o relacionamento interpessoal, mantendo-as distantes e, muitas vezes, não compreendidas pela maioria das pessoas. O presente estudo teve como objetivo avaliar os efeitos da adaptação do Sistema de Comunicação por Troca de Figuras (PECS - The Picture Communication System), aplicado ao contexto do Curriculum Funcional Natural (PECSAdaptado), na comunicação de pessoas com Autismo Infantil, que não apresentavam linguagem oral e/ou fala funcional. Como objetivo secundário, o estudo teve a intenção de verificar se o PECS-Adaptado favoreceria o aparecimento da fala. Para tanto, o estudo foi desenvolvido no Centro Ann Sullivan do Brasil - CASB, localizado na cidade de Ribeirão Preto, Estado de São Paulo. Para verificar os efeitos da intervenção deste estudo, foi realizado um delineamento do tipo AB e replicado em 4 meninos, com idades variando entre 5 e 8 anos de idade, com diagnóstico de Autismo Infantil, e envolveu 2 fases: linha de base e intervenção. Para o treinamento das 5 fases do PECS-Adaptado, foram utilizadas as figuras do PCS (Picture Communication System). As sessões de treinamento e coleta de dados ocorreram no decorrer de 2 anos. Os resultados mostraram que todos os participantes apresentaram mudanças no comportamento comunicativo, adquiriram vocabulário expressivo de algumas palavras, alguns sons e uso de figuras, que variou entre 25 e 61, sendo sempre utilizadas com função comunicativa. Os dados obtidos sugerem que a utilização de figuras com a finalidade de interação e solicitação de algo desejado parece ter contribuído para o aparecimento de sons, palavras e gestos usados com função comunicativa pelos participantes. No entanto, outros estudos devem ser encorajados, assim como a própria extensão do uso do PECS-Adaptado a outras pessoas com diferentes diagnósticos, mas que poderiam se beneficiar do uso da comunicação alternativa. Os resultados obtidos com o presente estudo são indicativos que o PECS-Adaptado, por ter como elemento básico a troca de figuras de interesse dos participantes, através da ação interativa, poderá contribuir futuramente no processo de inclusão dessas pessoas, não somente no ambiente escolar, como também na família e na comunidade.
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Rydé, Carl. "Erfarenheter av uppföljning efter gallring och föryngringsavverkning för att nå kraven i miljöcertifieringssystemen FSC och PEFC." Thesis, Linnéuniversitetet, Institutionen för skog och träteknik (SOT), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-27326.
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Miljöcertifieringssystemen PEFC och FSC ställer krav på uppföljning och revision för att säkerställa att kraven och kvalitén uppnås. Studiens syfte var att belysa de skogliga maskinentreprenörerna och förvaltarnas/virkesinköparnas erfarenheter av arbete med uppföljning inom miljöcertifierat skogsbruk. Materialet insamlades genom telefonintervjuer och analyserades med kvalitativ innehållsanalys, vilket ledde fram till resultatet. Uppföljningen och traktdirektivet har en viktig roll för att nå miljöcertifieringarnas krav. Dialog och delaktighet mellan de olika yrkesgrupperna var viktig, enligt respondenterna, för att miljöcertifieringen ska nå en hög kvalité och för att skapa engagemang och vilja att förbättra arbetet.The environmental certification systems PEFC and FSC require follow-up and auditing to ensure that the requirements are followed and that quality is achieved. The purpose of this study was to illuminate the experience of machine entrepreneurs, forestry managers and timber buyers of work with evaluation of environmental certified forestry. Data was gathered through telephone interviews and was analysed using qualitative content analysis. Evaluation and contract directives have an important role in achieving environmental certification requirements. Dialogue and co-operation between the different groups is important, according to respondents, for environmental certifications to achieve high quality and to create commitment and desire to improve the work.
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Krekel, Daniel Verfasser], Detlef [Akademischer Betreuer] [Stolten, and Hermann-Josef [Akademischer Betreuer] Wagner. "Betriebsstrategien für Brenngaserzeugungssysteme zur Anwendung in HT-PEFC-Hilfsstromaggregaten / Daniel Krekel ; Detlef Stolten, Hermann-Josef Wagner." Aachen : Universitätsbibliothek der RWTH Aachen, 2017. http://d-nb.info/1162845643/34.
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Krekel, Daniel [Verfasser], Detlef [Akademischer Betreuer] Stolten, and Hermann-Josef [Akademischer Betreuer] Wagner. "Betriebsstrategien für Brenngaserzeugungssysteme zur Anwendung in HT-PEFC-Hilfsstromaggregaten / Daniel Krekel ; Detlef Stolten, Hermann-Josef Wagner." Aachen : Universitätsbibliothek der RWTH Aachen, 2017. http://nbn-resolving.de/urn:nbn:de:101:1-2018071607583149820065.
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Rouanet, Carine. "Investigation du mécanisme d'action du système de régulation impliquant PecS chez la bactérie phytopathogène Erwinia chrysanthemi." Paris 7, 2002. http://www.theses.fr/2002PA077167.
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Bergman, Elin, and Sofie Levander. "Återanvändning som kommunikativ resurs : En samtalsanalytisk studie av kommunikation med PECS hos en pojke med diagnosen autism." Thesis, Linköping University, Linköping University, Department of Clinical and Experimental Medicine, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15714.
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Communicative recycling, to repeat utterances uttered by oneself or others, is a common phenomenon in all societies and languages. The talk of persons with autism often features recycling. The aim of this study was to identify different forms of recycling in communication involving a boy with autism and to describe its functions. Communication between the boy with autism, who used Picture Exchange Communication System (PECS) to communicate, and his parents and teachers was videotaped. The conversations took place in familiar settings, in the boy’s home and at his pre-school. The theoretical approach in the present study was Conversation Analysis (CA). The results provide further support for other studies in that recycling is an important interactional resource for children with limited linguistic capacities. The boy recycled the conversational frames taught in PECS and accommodated these to fit the context. The use of frames also enabled him to communicate with sentences. The transcribed examples exhibited diect as well as delayed recycling of other persons utterances made by the boy. The communicative recycling found in this study fulfilled all parts of the five-folded definition of functions presented by Tannen (1987): facilitating production and comprehension, creating a sense of connection, being a communicative resource enabling interaction and creating coherence as interpersonal involvement. The communicative recycling enabled the boy and his conversational partners to share communicative conventions. The use of recycling in conversations by people with autism may be a step towards a more generative use of language.
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Wilbrand, Christiane Verfasser], Detlef [Akademischer Betreuer] [Stolten, and Eike [Akademischer Betreuer] Stumpf. "Reformierung von BtL-Kraftstoffen für die HT-PEFC in luftfahrttechnischen Systemen / Christiane Wilbrand ; Detlef Stolten, Eike Stumpf." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1194066992/34.
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Wilbrand, Christiane [Verfasser], Detlef [Akademischer Betreuer] Stolten, and Eike [Akademischer Betreuer] Stumpf. "Reformierung von BtL-Kraftstoffen für die HT-PEFC in luftfahrttechnischen Systemen / Christiane Wilbrand ; Detlef Stolten, Eike Stumpf." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1194066992/34.
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Rylander, Anna. "Naturhänsyn vid föryngringsavverkningar : En jämförelse mellan certifierade och o-certifierade hyggen." Thesis, Linnéuniversitetet, Institutionen för skog och träteknik (SOT), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-44497.
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A growing number of Swedish forest owners are choosing to certify their forestry. However, there appears to be a lack of field surveys which describe differences between certified and non-certified forests concerning the degree of completed environmental considerations. In order to know to what extent certified forests contribute towards improved environmental consideration, we need studies on how large the difference is in relation to non-certified forests. Differences between certified and non-certified forest clearings were quantified through an inventory of the number of retention trees, dead trees and snags. The result showed that the retained number of the investigated parameters varied greatly between individual clearings, regardless of certification status. However, the results suggested that the certified clearings had an average higher incidence ofthe investigated parameters. In comparison to statistics of southern Sweden's average, the results also suggested that the certified clearings (from the county “Blekinge”) most of the time had a higher incidence of the investigated parameters, while the non-certified clearings most of the time had a lower incidence of the investigated parameters. The environmental considerations on neither the certified nor the non-certified clearings were found to be near the highest amount that could be required by the Swedish forestry act. This observation is interesting, especially since the certified clearings would be expected to maintain a consistently high level in relation to the law requirement.
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Genevey, Daniel Bruno. "Transient Model of Heat,Mass,and Charge transfer as well as Electrochemistry in the Cathode Catalyst Layer of a PEMFC." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/36286.
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A transient model of the cathode catalyst layer of a proton exchange membrane fuel cell is presented. The catalyst layer structure can be described as a superposition of the polymer membrane, the backing layer, and some additional platinum particles. The model, which incorporates some of the features of the pseudo-homogeneous models currently present in the literature, considers the kinetics of the electrochemical reaction taking place at the platinum surface, the proton transport through the polymer agglomerates, and the oxygen and water transport within the pores as well as the membrane material of the catalyst layer. Due to the lower porosity of this region and the higher liquid water content, the catalyst layer can be current limiting in the fuel cell. Furthermore, since the cost of the catalyst material is critical, it is important to have a model predicting the effective utilization of this catalyst layer as well as one, which gives insights into how it might be improved.
Equations are presented for the mass conservation of reactants and products, the electrical and ionic currents, and the conservation of energy. A discussion of a number of the closure relations such as the Butler-Volmer equation employed is included as is a discussion of the initial and boundary conditions applied. The mathematical model is solved using a finite elements approach developed at the I.U.S.T.I.Master of Science
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King, Melissa Lynne. "Effectiveness of the iPad in Enhancing the Mand Repertoire for Children with Autism." OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/673.
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The iPad with the Proloquo2Go application has taken the world of autism by storm, and given individuals that do not have a voice, a voice. This study looks at the effectiveness of the iPad with the Proloquo2Go application to enhance the manding repertoire for children with autism. Participants included three children (2 girls and 1 boy) diagnosed with an autism spectrum disorder, or exhibiting characteristics of an autism spectrum disorder, between the ages of 3 and 5. A multiple probe design across participants was used to assess the effectiveness of the iPad. Methods included completing The Reinforcer Assessment for Individuals with Severe Disabilities (RAISD) with the parents and/or teachers of each participant and running a six stimuli preference assessment before implementing each Phase. Pretest probes were conducted before implementing Phases 1 through 4. These phases were comparable to Phases 1 through 4 of the Picture Exchange Communication System (PECS) (Bondy & Frost, 1994). Results of this study support that children with autism can acquire the skills needed to mand using the iPad with the Proloquo2Go application with training comparable to that of the Picture Exchange Communication System (Bondy & Frost, 1994). In addition, vocal requesting increased for the participants during the training phases in comparison to pretest probes.
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Salomoni, Silvia. "L'impronta ambientale dei servizi: il caso della ristorazione scolastica." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/18121/.
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La metodologia PEF – Product Environmental Footprint, rappresenta il metodo raccomandato dalla Commissione Europea per la quantificazione dell’impatto ambientale di prodotti e servizi, finalizzato a favorirne il confronto, come stimolo alla competitività delle organizzazioni. Nel presente studio tale metodologia è stata applicata e discussa per la prima volta a livello internazionale ad un servizio, in particolare ad un segmento specifico del servizio di ristorazione scolastica svolto da CAMST. Tale studio ha permesso di analizzare e discutere un’applicazione concreta della PEF sui servizi e di validare e fornire input di miglioramento per la Product Environmental Footprint Category Rules (PEFCR) elaborata da ENEA, regole specifiche per il calcolo dell’impronta ambientale che definiscono nel dettaglio come condurre uno studio PEF per la specifica applicazione. Dopo la definizione degli obiettivi dello studio, che comprendono sia gli obiettivi generali dello studio che quelli specifici del committente, viene descritto nel dettaglio la raccolta ed elaborazione dei dati, la definizione del modello concettuale, la sua realizzazione con il software GaBi e infine l’interpretazione dei risultati. I risultati sono stati discussi in relazione a due principali aspetti. Il primo riguarda l’analisi dei risultati dello studio PEF in relazione agli obiettivi dello studio secondo l’approccio suggerito dalla PEFCR, quindi oltre a testare l’applicabilità della PEFCR sono state individuate le complessità di carattere metodologico fornendo un primo contributo migliorativo alle problematiche identificate. Il secondo aspetto riguarda l’analisi dei risultati adottando un diverso livello di dettaglio che potesse rispondere e fornire supporto alle richieste del committente. A questo proposito sono stati individuati gli aspetti più significativi del servizio su cui mettere in atto azioni strategiche da attuare in ottica di miglioramento del servizio.
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Pu, Hansong. "An Analysis of Preferred Equity Redemption Cumulative Stock." Thesis, University of North Texas, 1994. https://digital.library.unt.edu/ark:/67531/metadc277588/.
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This dissertation examines whether Percs, Preferred Equity Redemption Cumulative Stocks, are properly priced regarding to the relevant securities, such as the underlying common stock, the long-term call option of the stock, and so on. Test results indicate that Percs were overpriced with respect to the equivalent packages composed of the relevant securities. Further tests on arbitrage restrictions show that transaction costs would prevent arbitrage profits. This dissertation also examines the market reactions to Percs offerings. Test results reveal that the market reactions to the announcement of Percs offering and the actual issuance are both significantly negative. Compared to the market reaction on common stock offering announcement, the market reaction on Percs offering announcement is weaker. The overpricing of Percs and the weaker reaction of the market suggest that Percs may have advantages in transaction costs, taxes and some corporate finance issues.
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Rosén, Tomas. "Determination of water saturation dependent gas transport properties of PEFC gas diffusion layers via the Lattice Boltzmann method." Thesis, KTH, Mekanik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-41814.
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Haddou, Marie. "Complexes de polyélectrolytes : Morphologies, cinétique et thermodynamique d'assemblage." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0031.
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Les complexes de polyélectrolytes (PECs) sont typiquement formés par interaction électrostatique entre deux polyélectrolytes de charge opposée. Alors que de nombreuses études ont été consacrées aux propriétés de ces complexes, l'objectif de la thèse est de mieux comprendre le rôle de l’intensité de l’interaction entre deux polyélectrolytes sur la morphologie des complexes ainsi que la cinétique et la thermodynamique de la complexation. Différents systèmes complexants, faibles et forts, donnant lieu à la formation de coacervats ou de précipités ont été choisis et étudiés sur une large gamme de rapport de charges (Z[+]/[-]) afin d'obtenir différents états physiques (soluble, colloïdal, phase dense). La morphologie des complexes a été déterminée par microscopie (optique, fluorescence, force atomique) et diffusion de rayonnement (lumière, neutrons). La cinétique et la thermodynamique de complexation ont été étudiées par utilisation respective d'un mélangeur à flux stoppé et de la calorimétrie de titration isotherme. Les résultats obtenus permettent de mettre en évidence un certain nombre de caractéristiques permettant de distinguer les systèmes complexants forts et faibles. En particulier, les complexes forts sont hors équilibre d'un point de vue thermodynamique et en conséquence ils présentent une forte dépendance aux conditions initiales de complexation. Un autre aspect important et qui pourrait être à l'origine de la distinction entre les complexes forts et faibles est l'énergie d'hydratation des polyélectrolytes qui a été déterminée pour de nombreux polyélectrolytes et corrélée aux propriétés des complexesComplexes of polyelectrolytes (PECs) are oppositely charged polymers assemblies held together by electrostatic interaction. As the non-covalent assembly of macromolecules/colloids in solution has been thoroughly investigated over the last decade with a particular emphasis put on the morphology of the final aggregates as a function of the building blocks-chemistry, the objective of this thesis is to come to a better understanding of the influence of interaction strength between polyelectrolytes on complexes morphologies, as well as kinetics and thermodynamics of the complexation. For this study, weakly and strongly interacting systems given rise to coacervate and precipitate phases has been elected. Those systems have been studied on a wide charge ratio scale (Z[+]/[-]) to span several physical states of the PECs (soluble and colloidal PECs, dense phases). Morphologies of assemblies are assessed by microscopy (optical, fluorescence, atomic force) and scattering techniques (neutron, light). Kinetics and thermodynamics of the complexation process are studied by use of a stopped-flow mixing device and an isothermal titration calorimeter. Results gave us keys to discriminate strongly interacting systems from weakly interacting ones. In particular, the ‘strong systems’ are showed to be non-equilibrium assemblies, ie. the formulation pathway or the way these different macromolecules are coming into contact is then a key step. Another important aspect that could explain the complexation process behavior is the hydration energy of the polyelectrolytes. Calorimetry measurements have been performed for numerous polyelectrolytes and then correlated to complexes properties