Dissertations / Theses on the topic 'HDDG'
To see the other types of publications on this topic, follow the link: HDDG.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'HDDG.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Sheridan, Richard Stuart. "Optimisation of HDDR processing parameters of sintered NDFEB magnets." Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/4929/.
Full textAbstract:
In recent years rare earth metals have hit the headlines due to supply restrictions of neodymium and dysprosium from the main supplier China. The work in this thesis investigates the possibility of recycling sintered NdFeB-type magnets using a combination of hydrogen decrepitation (HD) and the HDDR process (Hydrogenation Disproportionation Desorption and Recombination). In this work the development of microstructure during the HDDR process has been identified and the route taken by hydrogen during absorption and desorption. The microstructure and magnetic properties have been shown to be affected by the process temperature, disproportionation pressure and recombination pressure and time. Sample batches up to 100g exhibit little variation in magnetic properties however 400g batches result in large variations partially due to incomplete recombination. By increasing the disproportionation pressure it was possible to simultaneously process mixed scrap feeds with different Dy and Co levels, however a large variation in magnetic properties was also observed. Optimal processing of sintered Nd\(_{13.4}\)Dy\(_{0.7}\)Fe\(_{78.6}\)Al\(_{0.7}\)Nb\(_{0.4}\)B\(_{6.3}\) was performed by in-situ HD followed by HDDR at 880\(^o\)C with a disproportionation pressure of 1500mbar and recombination under vacuum. The resultant powder exhibited a remanence of 1.08 T, coercivity of 840 kAm\(^{-1}\) and maximum energy product of 178 kJm\(^{-3}\).
2
Fengming, Li. "Modeling and Control of Algae Harvesting, Dewatering and Drying (HDD) Systems." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1333480231.
Full text
3
Silva, Suelanny Carvalho da. "Nanocompósitos à base de Pr2Fe14B/ α - Fe para aplicações térmicas." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-29042013-101915/.
Full textAbstract:
Neste trabalho, pós magnéticos nanoestruturados de PrxFe94-xB6 (x = 6, 8, 10 e 12) foram preparados a partir da combinação do processo de hidrogenação, desproporção, dessorção e recombinação (HDDR) e moagem de alta energia entre uma liga em estado bruto de fusão (Pr14Fe80B6) e Fe-α em pó. As nanopartículas produzidas apresentaram propriedades magnéticas e microestruturais comparáveis aos estudos realizados em hipertermia. O tempo ideal para obtenção de nanopartículas magnéticas é de 5 horas (a 900 rpm). Foi constatado que quanto maior o tempo de moagem, maior o percentual de carbono nas partículas (0,05 - 3,43 % C). O carbono é proveniente do ácido oléico adicionado como surfactante na etapa de moagem. Os nanocompósitos obtidos exibiram forças coercivas entre 80 Oe (6,5 kAm-1) e 170 Oe (13,5 kAm-1), e momentos magnéticos variando entre 81 - 129 Am2kg-1. A partir da difração de raios X foram identificadas apenas duas fases em todas as amostras: Fe-α e a fase magnética Pr2Fe14B. Nanopartículas isoladas com diâmetro aproximado de 20nm foram analisadas. Todas as composições estudadas apresentaram aquecimento proveniente da exposição a um campo magnético alternado (f = 222 kHz e Hmax ~3,7 kAm-1) comparáveis aos reportados na literatura. As variações de temperaturas (ΔT) dos pós foram: 51 K referente à composição de Pr6Fe88B6, 41 K para Pr8Fe86B6, 38 K no composto com 10% at. Pr (Pr10Fe84B6) e 34 K em Pr12Fe82B6. As taxas de absorção específicas estimadas foram de 201 Wkg-1 para a composição Pr6Fe88B6, 158 Wkg-1 para a composição Pr8Fe86B6 e 114 Wkg-1 para as composições Pr10Fe84B6 e Pr12Fe82B6.In this work, PrxFe94-xB6 (x = 6, 8, 10 and 12) nanostructured powders were prepared by a combination of hydrogenation, disproportionation, desorption and recombination (HDDR) process with high energy milling applied to the mixture of an as-cast alloy (Pr14Fe80B6) and α-Fe. The produced nanoparticles showed magnetic properties comparable to those reported in hyperthermia studies. The optimal time to obtain the magnetic nanoparticles is 5 hours (at 900 rpm). It was verified that longer milling times cause an increase in carbon percentage on the particles. The carbon is derived from oleic acid added as a surfactant in the milling step. The nanocomposites exhibit coercive force ranging from 80 Oe (6.5 kAm-1) to 170 Oe (13.5 kAm-1) and magnetic moments in the range of 81 129 Am2kg-1. From the x-ray diffraction analyses, only two phases were found in all samples: α-Fe and the magnetic phase Pr2Fe14B. Individual nanoparticles with diameter of about 20 nm were verified. The samples studied presented heating when exposed to an alternating magnetic field (f = 222 kHz e Hmax ~3.7 kAm-1) comparable to reported in literature. Temperature variations (ΔT) of the powders were: 51 K for Pr6Fe88B6, 41 K for Pr8Fe86B6, 38 K for Pr10Fe84B6 and T = 34 K for Pr12Fe82B6. The specific absorption rates (SARs) of the powders were 201 Wkg-1 for Pr6Fe88B6 composition, 158 Wkg-1 on the composition Pr8Fe86B6, and 114 Wkg-1 for Pr10Fe84B6 and Pr12Fe82B6 compositions.
4
Sun, Peng. "HPV-16 E6, hDlg and Connexin 43 in cervical carcinogenesis." Thesis, University of Glasgow, 2005. http://theses.gla.ac.uk/5003/.
Full textAbstract:
Disruption of gap junctional intercellular communication and/or Connexins (the channel proteins of gap junctions) is frequently reported in malignant cell lines and tumours. Many tumor cells exhibit aberrant gap junctional intercellular communication (GJIC), which can be restored by transfection with Connexin genes. Of the Connexin family, Connexin 43 has attracted the most attention as it is widely expressed in many tissues and Connexin 43 gap junctions correlate with various physiological functions. Connexin 43 is a short-lived protein (half-life of 1-3 h in cultured cells), both lysosomes and proteasomes having been reported to be involved in its degradation. Certain human papillomaviruses (HPV) associated with the development of cancers, especially of the cervix, have been reported to downregulate GJIC in vitro. There is also evidence for reduced gap junctions in cervical dysplasia. The association between HPV and GJIC, and the mechanism and consequence of deregulated GJIC in cervical tumour progression, remains unclear. In HPV-16 associated cervical cancer, the viral oncogene E6 inactivates the tumour suppressor p53, but also has p53- independent functions in tumour progression. One of these may involve interaction with hDlg (the human homologue of Drosophila Discs Large), a tumour suppressor present in epithelial cells at sites of cell-cell contact and which regulates cell polarity and attachment. hDlg contains three PDZ protein-protein interaction domains, the second PDZ domain of which binds E6. Connexin 43 also has a PDZ binding domain in its C-terminus. Previously, it was demonstrated that Connexin 43 relocates from the membrane to the cytoplasm in a novel HPV-16 E6-containing cervical epithelial cell line (named WI2GPXY) that is fully transformed and invasive and deficient in gap-junctional intercellular communication (Aasen T et aI., 2003 Oncogene 22, 7969- 7980). The overall aim of this project was to investigate the relationship of loss of gap junctions to malignant progression by comparing the properties of W12GPXY with those of the non-malignant parental cell line, WI2G, from which W12GPXY was derived. First, microarray was used to identify global differences in RNA expression between the two cell lines, large differences were seen in expression of angiogenesis-related genes and they were confirmed by Real-Time RT-PCR for three genes, IL-8, VEGF and FGF-2. No significant differences were noted for connexin genes but there were differences in MAGUK family members including hDlg. However, protein expression studies by western blot and immunofluorescence staining showed a significant increase (2.9 fold) of HPV-16 E6 in W12GPXY cells, which co-localises with hDlg in the cytoplasm. Connexin 43 also binds hDlg. Treatment ofW12GPXY cells with Leptomycin B to trap E6 in the nucleus or siRNA knockdown of E6 abrogate the relocation and co-location of hDlg and endogenous wild type Connexin 43 and restore Connexin 43 gap junction at points of cell-cell contact. Further, when C33a cells (HPV -negative cervical tumour cells which normally retain large Connexin 43 gap junctions) are transfected with HPV -18 wild type E6, changes in localisation of Connexin 43 and hDlg are consistent with those in W12GPXY cells. However, C33a cells transfected with a mutant E6 lacking the hDlg binding site retain Connexin 43 gap junction plaques. Finally, Connexin 43 associates with hDlg through its PDZ-binding domain and this is required for its relocalisation to the cytoplasm in W12GPXY cells. The results suggest that increased cytoplasmic E6 associated with malignant progression of W12GPXY cells redistributes Connexin 43 from membrane junctions into the cytoplasm by a mechanism involving binding of hDlg to the Connexin 43 C-tenninal tail. The findings have uncovered a new role for hDlg in trafficking of Connexin 43. It also provides a novel mechanism for the loss of gap junctional intercellular communication during malignant progression of squamous epithelial cells. The specific roles played by lysosomes and proteasomes in the degradation of Connexin 43 in W12GPXY cells were also studied. The results suggest the involvement of both proteolytic pathways, although the lysosome seems to be the major compartment for Connexin 43 degradation. Association with HPV-16 E6 and hDlg together with proteasome activity seems to be required for Connexin 43 redirection from the cell membrane and transport into the lysosomal degradation pathway. Taken together, these results suggest that Connexin 43 gap junction intercellular communication was lost from the cell membrane requiring maintenance of E6 and hDlg complexes for proteasomal internalization and consequently transport into lysosomal compartment for degradation in W12GPXY cells.
5
Fujita, Akira. "A study on magnetic anisotropy induced in the HDDR process." Thesis, University of Birmingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343855.
Full text
6
Shivane, Chetan. "Environment-friendly anti-corrosion 'Superprimers' for HDG." Cincinnati, Ohio : University of Cincinnati, 2006. http://www.ohiolink.edu/etd/view.cgi?acc%5Fnum=ucin1140205616.
Full textAbstract:
Thesis (M.S.)--University of Cincinnati, 2006.Title from electronic thesis title page (viewed Apr. 20, 2006). Includes abstract. Keywords: Superprimer,Corrosion, Coatings, Silanes, primers, HDG Includes bibliographical references.
7
SHIVANE, CHETAN. "ENVIRONMENT-FRIENDLY ANTI-CORROSION 'SUPERPRIMERS' FOR HDG." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1140205616.
Full text
8
Cannesan, Nicolas. "The production and characterisation of anisotropic HDDR (Pr,Nd)FeB-based powders." Thesis, University of Birmingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.402527.
Full text
9
Konigsberg, Paul C. (Paul Carey) 1976. "Acquisition behavior for a HDD interpolative timing recovery system." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/80089.
Full textAbstract:
Thesis (S.B. and S.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, June 1999.Includes bibliographical references (leaf 20).
by Paul Carey Konigsberg.
S.B.and S.Eng.
10
Engerroff, Juliano Assis Baron. "Obtenção via HDDR de pós nanocristalinos anisotrópicos à base de Nd-Fe-B." reponame:Repositório Institucional da UFSC, 2015. https://repositorio.ufsc.br/xmlui/handle/123456789/169331.
Full textAbstract:
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Ciência e Engenharia de Materiais, Florianópolis, 2015.Made available in DSpace on 2016-10-19T12:42:51Z (GMT). No. of bitstreams: 1 338942.pdf: 2648527 bytes, checksum: cb886767d486111772a926000df5ded9 (MD5) Previous issue date: 2015
O mercado de ímãs permanentes para aplicações de alto desempenho é hoje dominado pelos ímãs à base de terras raras (TR), como os ímãs de Nd-Fe-B. Neste contexto, uma das técnicas mais promissoras atualmente para obtenção de pós para ímãs compósitos é o processo d-HDDR (hidrogenação-desproporção-dessorção-recombinação, d = dinâmico), tratamento este realizado a alta temperatura sob atmosfera de hidrogênio a fim de promover o endurecimento magnético pelo refinamento da microestrutura, além de induzir textura magnética que, por consequência, maximiza o valor de produto de energia máximo. O presente trabalho tem como foco o estudo do processo d-HDDR aplicado a uma liga à base de Nd-Fe-B da classe comercial N42 para obtenção de pós nanocristalinos próprios para preparação de ímãs anisotrópicos. Sendo assim, elaborou-se um ciclo próprio de d-HDDR de referência e, a partir do mesmo, determinou-se as influências das seguintes variáveis: tempo de patamar para desproporção; tempo de patamar para recombinação final e temperatura de patamar para desproporção e recombinação. A caracterização magnética das amostras se deu por meio de um histeresígrafo. Já a microestrutura foi caracterizada via difração de raios X e microscopia eletrônica de varredura com emissão de campo. Os resultados mostraram que o processo d-HDDR estudado foi efetivo para obtenção de pós nanocristalinos com tamanho de grão de aproximadamente 300 nm e com grau de alinhamento de 80%. Para os intervalos de tempo de patamar de desproporção analisados, não há mudanças significativas dos valores de propriedades magnéticas quando comparados aos valores de referência, mantendo-se em Br ? 1,07 T, Hcj ? 700 kA/m e (BH)max ? 75 kJ/m³. Já para diferentes intervalos de tempo de patamar para recombinação final, ocorrem mudanças significativas dos valores de propriedades magnéticas, havendo um patamar de valores máximos em intervalos próximos ao de referência, onde Br ? 1,1 T, Hcj ? 700 kA/m e (BH)max ? 85 kJ/m³. Considerando as diferentes temperaturas de patamar para desproporção e recombinação avaliadas, os máximos valores de propriedades magnéticas atingidos foram: Br ? 1,05 T, Hcj ? 700 kA/m e (BH)max ? 80 kJ/m³.
Abstract : Rare earth-based magnets, e.g. Nd-Fe-B, now dominate the market of permanent magnets used for high performance applications. In this regard, one of the most promising techniques is currently the so called d-HDDR process (hydrogenation-disproportionation-desorption-recombination, d = dynamic), which includes a set of high temperature treatments under hydrogen atmosphere, in order to ensure magnetic hardening by microestrutural refinement and induce magnetic texture, whose consequently maximize maximum energy product value. This work focuses on the study of d-HDDR process applied to Nd-Fe-B-based alloy of N42 commercial class in order to obtain nanocrystalline powders, proper for anisotropic magnets fabrication. Therefore, it was prepared a proprietary d-HDDR cycle in which the following variables were studied: holding time for disproportionation; holding time for final recombination and disproportionation-recombination temperature. Magnetic characterization of the samples was carried out by means of a histeresigraph, whereas the formed phases were characterized via X-ray diffraction and the microstructure by scanning electron microscopy. Results showed that d-HDDR process was effective for obtaining anisotropic powders with grain size of approximately 300 nm and alignment degree of 80%. For the studied interval of holding time for disproportionation, no significant change of the magnetic values occurred if compared to the reference cycle, with values of Br ? 1.07 T, Hcj ? 700 kA/m e (BH)max ? 75 kJ/m³. However, for different time intervals in final recombination, there are significant changes in the values of magnetic properties, with a plateau of maximum values near the reference range, in which Br ? 1.1 T, Hcj ? 700 kA/m e (BH)max ? 85 kJ/m³. Regarding the different studied temperatures for disproportionation and recombination, the maximum values of magnetic properties achieved were Br ? 1.05 T, Hcj ? 700 kA/m and (BH)max ? 80 kJ/m³.
11
Perugi, Fabien. "HDLG, un médiateur cellulaire de l'assemblage des rétrovirus VIH-1 et HTLV-1." Paris 7, 2008. http://www.theses.fr/2008PA077020.
Full textAbstract:
La compréhension des différentes étapes conduisant à la production des particules virales est, à l'heure actuelle, un axe majeur dans la recherche en rétrovirologie. Dans le souci de trouver une protéine cellulaire capable de faire le pont entre les précurseurs Gag et Env chez HTLV-1, notre équipe a identifié hDIg, lors d'un crible double hybride, comme un des partenaires cellulaires de la région cytoplasmique des glycoprotéines d'enveloppe du HTLV-1. Une étude approfondie de l'interaction de hDIg avec les protéines structurales d'enveloppe (Env) a montré que cette interaction est nécessaire dans les étapes de fusion membranaire lors de la transmission cellule- cellule du HTLV-1. Nous avons aussi mis en évidence une interaction entre hDIg et le précurseur Gag au niveau de sites enrichis en Env l'hypothèse selon laquelle hDIg est impliquée dans la rencontre Env/Gag chez HTLV-1. A partir de ces observations et en tenant compte des fortes homologies structurales et fonctionnelles constatées entre les domaines des protéines Gag des rétrovirus, nous avons choisi d'étudier le rôle de hDIg dans le cycle viral du VIH-1. Dans ce cas, hDIg semble être une protéine qui altère naturellement l'infectiosité de l'ensemble de la population virale issue de la cellule infectée, via une rétention de Gag à la membrane plasmique. Cette fonctionnalité de hDIg empêcherait Gag d'entrer dans une voie de trafic optimisée pour la rencontre Env/Gag et par conséquent plus efficace pour l'incorporation de Env dans les virions. Ainsi hDIg serait le premier facteur de restriction des étapes tardives découvert pour le VIH-1 dans le domaine de la rétrovirologieUnderstanding the various steps leading to the production of viral particles is, nowadays, a major axis of research in retrovirology. In order to find a cellular protein able to link Gag and envelope (Env) precursors of HTLV-1, we performed a two hybrid screen. First of ail, our team identified hDIg as a cellular partner of the cytoplasmic tail of the HTLV-1 envelope glycoproteins. Our study demonstrated that this interaction is needed for the late steps of membrane fusion during cell to cell transmission of HTLV-1. We also evidenced an interaction between Gag and hDIg in Env-enriched areas of the plasma membrane which suggests that hDIg could be a linker for Gag and Env precursors assembly. Based on these findings and the strong homologies of structure and functions between the domains of Gag precursors of different retroviruses, we focused our study on the role of hDIg in the viral cycle of HIV-1. In this case, hDIg seems to be a protein that negatively regulates the infectivity of HIV-1 particles, by retaining Gag proteins at the plasma membrane. We suggest that hDIg could prevent Gag precursors from reaching a trafficking pathway by optimizing the incorporation of Env into virions. Thus, hDIg would be the first restriction factor of the late steps of the HIV-1 lifecycle
12
Geier, Florian. "The differences between SSD and HDD technology regarding forensic investigations." Thesis, Linnéuniversitetet, Institutionen för datavetenskap (DV), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-44921.
Full textAbstract:
In the past years solid state disks have developed drastically and are now gaining increased popularity compared to conventional hard drives. While hard disk drives work predictable, transparent SSD routines work in the background without the user’s knowledge. This work describes the changes to the everyday life for forensic specialists; a forensic investigation includes data recovery and the gathering of a digital image of each acquired memory that provides proof of integrity through a checksum. Due to the internal routines, which cannot be stopped, checksums are falsified. Therefore the images cannot prove integrity of evidence anymore. The report proves the inconsistence of checksums of SSD and shows the differences in data recovery through high recovery rates on hard disk drives while SSD drives scored no recovery or very poor rates.
13
Magnusson, Fredrik. "Implementing a Backup-Scheme with the 3-2-1 Strategy : A Comparison of the Active Solution with a New Implemented 3-2-1 Backup-Scheme." Thesis, Mittuniversitetet, Avdelningen för informationssystem och -teknologi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-34347.
Full textAbstract:
Denna rapport tar upp teorin bakom sannolikhet, backuper och hårddiskar. Baserat på detta implementeras en backup-plan med hjälp av NASar, för att ersätta den redan existerande lösningen. Behovet utav en säkrare, mer tillförlitlig backup, samt expansionsmöjligheter då företaget har en stark tillväxt, lades fram tillsammans med en budget för att ta fram en lösning anpassad utefter det faktiska behovet. Denna plan baseras på teorin i kombination med tredje-parts resultat och har som utgångspunkt den budgeten som erhållits utav företaget, för att slutligen uppnå en hållbar, expanderbar och automatiserad backup. Fortsättningsvis behandlar rapporten implementering i existerande infrastruktur, automation och enkel hantering utav backup och varför en 3-2-1 lösning bör användas. Rapporten ser att efter den nya lösningen har implementerats är det mycket mindre risk för att data går förlorat samt att en övergripande ökning i hastighet och automation kan ses. Slutligen, med hjälp av standardiserat verktyg lägger denna rapport en godkänd grund för andra att använda i deras implementationer eller att gräva djupare inom tillförlitlighets världen.This report handles the theory behind probability, backups and hard drives. Based on this, a backup-scheme is implemented with the help of NASes, to replace the current solution. The need for a more secure, more reliable and a solution that is expandable due to the quick growth of the company, was put forward together with a budget to provide a solution suited after the effective need. This scheme is based upon theory in combination with third-party results and for this specific case has the budget, provided by the company, as a starting point to accomplish a sustainable, expandable and automated backup. Furthermore, this report implements this solution into the existing infrastructure where automation and simple handling of backups and why a 3-2-1 solution will be used. The report finds that after the new solution is implemented there is significantly less risk of data failure as well as an overall increase in speed and automation. Finally, with the help of standardized tools this report lay a decent groundwork for others to use in their implementation or to dig deeper into the world of reliability.
14
Amorim, Felipe Guedes, and (92) 99537-5427. "Caracterização da infecção pelos vírus da hepatite B e D em plasma e tecido hepático de portadores crônicos." Universidade Federal do Amazonas, 2018. https://tede.ufam.edu.br/handle/tede/6722.
Full textAbstract:
Submitted by Felipe Guedes Amorim (felipe_guedes17@hotmail.com) on 2018-10-22T13:50:51Z
No. of bitstreams: 3
CARACTERIZAÇÃO DA INFECÇÃO PELOS VÍRUS DAS HEPATITES B E D EM PLASMA E TECIDO HEPÁTICO DE PORTADORES CRÔNICOS.pdf: 3452813 bytes, checksum: e271da19b24cd37ea8a4e33354900f20 (MD5)
CARTA DE ENCAMINHAMENTO.pdf: 414411 bytes, checksum: 9dd0a540145c49dfcecf128512528fb0 (MD5)
ATA DE DEFESA.jpg: 705457 bytes, checksum: f4791ecb5b56473f31626ba9bbf907e4 (MD5)Approved for entry into archive by PPGBIOTEC Biotecnologia (ppg_biotec.ufam@yahoo.com.br) on 2018-10-22T14:18:55Z (GMT) No. of bitstreams: 3 CARACTERIZAÇÃO DA INFECÇÃO PELOS VÍRUS DAS HEPATITES B E D EM PLASMA E TECIDO HEPÁTICO DE PORTADORES CRÔNICOS.pdf: 3452813 bytes, checksum: e271da19b24cd37ea8a4e33354900f20 (MD5) CARTA DE ENCAMINHAMENTO.pdf: 414411 bytes, checksum: 9dd0a540145c49dfcecf128512528fb0 (MD5) ATA DE DEFESA.jpg: 705457 bytes, checksum: f4791ecb5b56473f31626ba9bbf907e4 (MD5)
Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2018-10-22T18:27:33Z (GMT) No. of bitstreams: 3 CARACTERIZAÇÃO DA INFECÇÃO PELOS VÍRUS DAS HEPATITES B E D EM PLASMA E TECIDO HEPÁTICO DE PORTADORES CRÔNICOS.pdf: 3452813 bytes, checksum: e271da19b24cd37ea8a4e33354900f20 (MD5) CARTA DE ENCAMINHAMENTO.pdf: 414411 bytes, checksum: 9dd0a540145c49dfcecf128512528fb0 (MD5) ATA DE DEFESA.jpg: 705457 bytes, checksum: f4791ecb5b56473f31626ba9bbf907e4 (MD5)
Made available in DSpace on 2018-10-22T18:27:33Z (GMT). No. of bitstreams: 3 CARACTERIZAÇÃO DA INFECÇÃO PELOS VÍRUS DAS HEPATITES B E D EM PLASMA E TECIDO HEPÁTICO DE PORTADORES CRÔNICOS.pdf: 3452813 bytes, checksum: e271da19b24cd37ea8a4e33354900f20 (MD5) CARTA DE ENCAMINHAMENTO.pdf: 414411 bytes, checksum: 9dd0a540145c49dfcecf128512528fb0 (MD5) ATA DE DEFESA.jpg: 705457 bytes, checksum: f4791ecb5b56473f31626ba9bbf907e4 (MD5) Previous issue date: 2018-07-18
Fundação de Amparo a Pesquisa do Amazonas (FAPEAM)
The hepatitis B virus (HBV) is responsible for a serious global public health problem, and the problem becomes even greater when coinfection or superinfection of D virus (HDV). It is estimated that of the 240 million people worldwide with chronic HBV infection, 15 million are carriers of HDV infection. Some regions of the Amazon Basin, particularly the State of Amazonas, are considered endemic areas of infection by these viruses. HDV is classified into eight different types (HDV-1-HDV-8) and HBV in ten (A-J). Thus, this research aims to characterize the genotypes of hepatitis B and D virus in plasma and hepatic tissue and to investigate possible association of genotypes with the evolution of the disease. Plasma and hepatic tissue samples from chronic HBsAg-reactive patients coinfected with HDV were analyzed. Plasma VHD viral load was quantified by real-time PCR; amplification of HBV DNA and VHD RNA by conventional PCR; direct sequencing of both viruses; phylogenetic analysis and research of resistance mutations in rt HBV. As a result, a total of 30 reactive HBsAg and Total Anti-HD patients, all from the State of Amazonas, were included in the study. Of these, 9/30 had both plasma and hepatic tissue samples. RNA-VHD was detected in 13/30 (46.67%) and HBV DNA in 11/30 (36.67%). Of the 09 plasma and hepatic tissue samples, VHD-RNA was detected in 2/9 (22.27%) and HBV DNA in 8/9 (88.89%). Of the 30 plasma samples submitted to VHD RNA quantification, viral load was obtained in 13/30 (46.67%). We also analyzed the 9 samples of hepatic tissue, obtaining viral load in 2/9 (22.27%). In the phylogenetic analysis, all the Delta sequences clustered in the clade VHD-3, already those of HBV, the genotypes A 15/19 (78%), D 2/19 (11%) and F 2/19 (11%). Concerning the search for antiviral resistance mutations in rt-HBV, 3/11 (27%) and 5/08 (62%) sequences isolated from plasma and hepatic tissue, respectively, showed resistance mutations. Conclusions: three HBV genotypes A, D and F were detected, independent of the source material; all extracted from delta were exclusively VHD-3; the viral load of the delta virus was higher in those extracted from hepatic tissue; a high percentage of mutations in the HBV polymerase region was detected, especially in isolated hepatic tissue sequences. Finally, the profile of the HBV and VHD genotypes found in the study reflects the same pattern found in the region by other authors.
O vírus da hepatite B (VHB) é responsável por um grave problema de saúde pública mundial, sendo que o problema torna-se ainda maior quando ocorre coinfecção ou superinfecção com o vírus D (VHD). Estima-se que das 240 milhões de pessoas no mundo portadoras crônicas de infecção pelo VHB, 15 milhões são portadoras de infecção pelo VHD. Algumas regiões da Bacia Amazônica, particularmente o Estado do Amazonas são consideradas áreas endêmicas de infecção por esses vírus. O VHD é classificado em oito diferentes tipos (VHD-1-VHD-8) e o VHB em dez (A-J). Sendo assim, esta pesquisa tem como objetivo, caracterizar os genótipos do vírus da hepatite B e D no plasma e tecido hepático e investigar possível associação dos genótipos com a evolução da doença. Foram analisadas amostras de plasma e de tecido hepático de pacientes portadores crônicos HBsAg reativos coinfectados com o VHD. Foi realizada a quantificação da carga viral do VHD no plasma por PCR em tempo real; amplificação do DNA-VHB e RNA-VHD por PCR convencional; sequenciamento direto de ambos os vírus; análise filogenética e pesquisa de mutações de resistência na rt do VHB. Como resultados, foram incluídos no estudo um total de 30 pacientes HBsAg e Anti-HD Total reativos, todos procedentes do Estado do Amazonas. Destes, 9/30 tinham simultaneamente amostras de plasma e tecido hepático. O RNA-VHD foi detectado em 13/30 (46,67%) e o DNA-VHB em 11/30 (36,67%). Das 09 amostras de plasma e tecido hepático o RNA-VHD foi detectado em 02/9 (22,27%) e o DNA-VHB em 08/9 (88,89%). Das 30 amostras de plasma submetidas a quantificação do RNA VHD, obteve-se a carga viral de 13/30 (46,67%). Também analisamos as 9 mostras de tecido hepático, obtendo-se a carga viral em 2/9 (22,27%). Na análise filogenética, todas as sequências de Delta agruparam-se no clado VHD3, já as de VHB, foram identificados os genótipos A 15/19 (78%), D 2/19 (11%) e F 2/19 (11%). Em relação à pesquisa de mutações de resistência à antivirais na rt-VHB, verificou-se que 3/11 (27%) e 05/08 (62%) sequencias isoladas do plasma e tecido hepático, respectivamente, apresentavam mutações de resistência. Conclusões: foi detectado três genótipos do VHB A, D e F, independente do material de origem; todos os extraídos de delta foram exclusivamente VHD-3; a carga viral do vírus delta, foi maior nos extraídos de tecido hepático; quanto ao perfil de mutações de resistência, foi detectado um percentual elevado de mutações na região da polimerase do VHB, principalmente nas sequências isoladas do tecido hepático. Por fim, o perfil dos genótipos do VHB e VHD encontrados no estudo reflete o mesmo padrão encontrado na região por outros autores
15
Freire, Thamires Batello. "Desenvolvimento e avaliação da segurança e eficácia de nanoemulsão com cafeína com ação na HDLG." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/9/9139/tde-01062017-162648/.
Full textAbstract:
.A Hidrolipodistrofia Ginoide (HDLG), popularmente conhecida como celulite, ocorre em 80 a 90% da população feminina após o período da puberdade, provém de uma modificação metabólica no tecido adiposo cutâneo. A cafeína, por sua vez, promove uma ação lipolítica e é muito utilizada por formuladores. Este projeto buscou obter nanoemulsão contendo, como ingredientes principais, tensoativos (Oleth-3; Oleth-20) e cafeína pelo método de emulsificação por (TIF). Foram desenvolvidas emulsões, sendo a F3, a mais translúcida com Temperatura clearing-boundary (Tcb) de aproximadamente 80 °C e temperatura de inversão de fase (TIF) de 85 °C. No Teste de Estabilidade Preliminar (TEP), a nanoemulsão não apresentou modificações nas suas características organolépticas, exceto no teste de estresse térmico no qual ocorreu separação de fases acima de 70°C. No Teste de Estabilidade Normal (TEN) a condição de 45,0 ± 2,0 °C apresentou instabilidade, nos demais valores de temperatura as nanoemulsões foram classificadas como normal. Os valores de pH para as condições de 25,0 ± 2,0 °C e 5,0 ± 2,0 °C decaíram no decorrer dos 90 dias, 13,7 e 2% respectivamente. Estes valores foram avaliados por ANOVA, seguido do Teste de Tukey, sugerindo que o armazenamento da F3 seja refrigerado. Os índices de polidispersão apresentaram desvio reduzido de 0,1. Indicando a presença de gotículas com alta polidispersibilidade e caráter monodisperso. O tamanho de gotícula na condição de 5,0 ± 2,0 °C teve tamanho e percentual de variação inferior em relação à condição 25,0 ± 2,0 °C. O potencial zeta no t0 foi de -3,9. O percentual de Transmitância no t0 e com t90 dias de TEN apresentou valores de 48,7 e 6,5% respectivamente, indicando uma perda da transparência no decorrer do tempo. A constante de Ostwald na condição de geladeira foi favorável para a estabilidade. No ensaio com a espectroscopia Raman foi comparado o espectro da cafeína em solução em diversos valores de pH e não foi observado o deslocamento de bandas e nem sua protonação. As bandas de cafeína encontradas na F3 foram compatíveis com as encontradas na solução de cafeína (1337; 652,5 e 558,2 cm-1). Não houve interação da cafeína anidra com o óleo Caprylic/Capric Triglyceride (TAAC) e nem com os tensoativos Oleth-3 e Oleth-20. A validação analítica do método foi linear, precisa e exata. Houve redução da concentração de cafeína ao longo do tempo da TEN, na condição de 5,0 ± 2,0 °C (15,1%). A eficiência de associação da cafeína na gotícula foi 4,8%. No ensaio de segurança de uso de nanoemulsão in vitro HET CAM - Hen\'s Egg Test - Chorioallantoic Membrane, o resultado de 1,4 classificou a nanoemulsão F3 como levemente irritante. No ensaio de permeação cutânea em membrana natural (pele humana) as concentrações permeadas não ultrapassaram a concentração de saturação do tampão Phosfate Saline (PBS) (48,96 µg/3mL). A solução com cafeína permeou mais que a nanoemulsão com cafeína F3, porém a nanoemulsão melhorou visualmente e sensorialmente a precipitação da cafeína.Ginoide Hydrolipodystrophy (HDLG), commonly known as cellulite, occurs in 80-90% of the female population after the puberty period, comes from a metabolic modification in cutaneous adipose tissue. Caffeine, in turn, promotes a lipolytic action and is widely used by formulators. This project obtained nanoemulsion containing as main ingredients surfactants (Oleth-3; Oleth-20) and caffeine by emulsification method by (TIF). Emulsions were developed, with F3 being chosen, the most translucent with clearing-boundary Temperature (Tcb) of approximately 80 °C and phase inversion temperature (TIF) of 85 °C. In the Preliminary Stability Test (PET), the nanoemulsion showed no changes in its organoleptic characteristics, except in the thermal stress test in which phase separation occurred above 70 °C. In the Normal Stability Test (TEN) the condition of 45.0 ± 2.0 °C showed instability, in the other temperature values the nanoemulsions were classified as normal. The pH values for the conditions of 25.0 ± 2.0 °C and 5.0 ± 2.0 °C declined over the course of 90 days, 13.7 and 2.0% respectively. These values were evaluated by ANOVA, followed by Tukey\'s test, suggesting that F3 storage should be refrigerated. The polydispersion indices showed reduced deviation of 0.1. Indicating the presence of droplets with high polydispersity and monodisperse character. The droplet size in the condition of 5.0 ± 2.0 °C had size and percentage of variation lower than the condition 25.0 ± 2.0 ° C. The zeta potential at t0 was -3.9. The percentage of Transmittance at t0 and with t90 days of TEN presented values of 48.7 and 6.5% respectively, indicating a loss of transparency over time. Evaluated constant of Ostwald, in the refrigerator condition was the most favorable for stability. In the Raman spectroscopy assay the caffeine spectrum was compared in solution at various pH values and the band displacement and its protonation were not observed. The caffeine bands found in F3 were compatible with those found in the caffeine solution (1337, 652.5 and 558.2 cm -1). There was no interaction of caffeine anhydrous with Caprylic/Capric Triglyceride oil (TAAC) nor with Oleth-3 and Oleth-20 surfactants. The analytical validation of the method was linear, precise and accurate. There was a reduction of the caffeine concentration over the TEN time, in the condition of 5.0 ± 2.0 °C (15.1%). The caffeine association efficiency in the droplet was 4.8%. In the safety assay of using nanoemulsion in vitro HET CAM - Hen\'s Egg Test - Chorioallantoic Membrane, the result of 1.4 ranked the nanoemulsion F3 as slightly irritating. In the natural membrane cutaneous permeation test (human skin) permeate concentrations did not exceed the saturation concentration of the (PBS) Phosfate Saline (48.96 µg/3 mL). The caffeine solution permeated more than the nanoemulsion with caffeine F3, but the nanoemulsion visually and sensorially improved the caffeine precipitation.
16
Nehmetallah, Georges. "Méthodes Galerkin discontinues hybrides couplées à des schémas de type explicite/implicite pour les équations de Maxwell instationnaires." Thesis, Université Côte d'Azur, 2020. http://www.theses.fr/2020COAZ4098.
Full textAbstract:
Dans cette thèse, nous étudions et développons différentes familles de schémas d’intégration en temps combinés avec une méthode Galerkin disontinue hybride (GDH) en espace pour les équations de Maxwell. Après avoir passé en revue les méthodes GDH pour l’équation de Poisson, les équations de Maxwell en domaine fréquentiel et les équations de Maxwell en domaine temporel avec une discrétisation temporelle totalement implicite dans la première partie, nous construisons une méthode GDH totalement explicite en temps pour les équations de Maxwell en 3D en domaine temporel dans la deuxième partie. Cette méthode est précise avec un ordre élevé en espace et en temps et peut être vue comme une généralisation d’un schéma GD classique basé sur des flux décentrés. En particulier, elle coïncide avec ce schéma pour un choix particulier du paramètre de stabilisation introduit dans la définition des traces numériques dans le cadre GDH. Nous présentons des résultats numériques visant à évaluer ses propriétés de convergence. Nous proposons ensuite une nouvelle technique de post-traitement pour cette dernière méthode que nous couplons avec un schéma de Runge-Kutta explicite. Le champ électromagnétique post-traité converge plus vite d’un ordre que la solution non post-traitée en norme H(curl) . L’approche proposée est locale, c’est-à-dire que la solution améliorée est calculée indépendamment dans chaque cellule du maillage, et à chaque pas de temps nécessaire. En conséquence, son calcul n’est pas coûteux, surtout si la région d’intérêt est localisée, soit dans le temps, soit dans l’espace. Nous présentons plusieurs expériences numériques mettant en évidence les propriétés de superconvergence du champs électromagnétique post-traité. Dans la dernière partie, nous proposons une méthodologie pour construire des méthodes hybrides explicites/implicites (IMEX) pour les équations de Maxwell. Nous présentons ces méthodes IMEX obtenues en séparant la formulation semidiscrète en parties grossières et fines, puis en appliquant trois schémas en temps différents, d’ordre allant de 1 à 3. Nous présentons des résultats numériques montrant que nos méthodes sont efficaces en terme de précision et en terme de temps de calcul. Nous choisissons des cas où les maillages localement raffinés sont indispensables pour la précision de la solution approchée : un domaine en forme de L où la solution présente une singularité, un domaine hétérogène avec une variation importante de la vitesse de l’onde et un dispositif de cristaux photoniques où les sphères en silicium sont très proches les unes des autresIn this thesis, we study and develop different families of time integration schemes combined with a hybrid discontinuous Galerkin (HDG) discretization in space for Maxwell’s equations. After presenting a review of HDG methods for Poisson equation, time-harmonic Maxwell’s equations and for the time-domain Maxwell’s equations with a fully implicit time discretization in the first part, we construct a fully explicit HDGTD method for the 3D time-domain Maxwell’s equations in the second part. This HDGTD method is high order accurate in both space and time and can be seen as a generalization of the classical DGTD scheme based on upwind fluxes. In particular, it coincides with the latter scheme for a particular choice of the stabilization parameter introduced in the definition of numerical traces in the HDG framework. We provide numerical results aiming at assessing its numerical convergence properties. Then we propose a novel postprocessing technique for the latter method that we couple with an explicit Runge-Kutta time-marching scheme. The postprocessed electromagnetic field converges one order faster than the unpostprocessed solution in the H(curl) -norm. The proposed approach is local, in the sense that the enhanced solution is computed independently in each cell of the computational mesh, and at each time step of interest. As a result, it is inexpensive to compute, especially if the region of interest is localized, either in time or space. We present several numerical experiments that highlight the superconvergence properties of the postprocessed electromagnetic fields. Pursuing our aim, we propose a methodology to construct hybrid explicit/implicit (IMEX) HDGTD methods for Maxwell’s equations in the last part. We present the IMEX HDGTD methods obtained from dividing the semi-discrete formulation into coarse and fine parts and then applying three different IMEX time-marching of three different orders (less or equal to 3). We present numerical results for various test cases. An L shape domain where we have a singularity in the solution, a heterogeneous domain where we have an important variation of the wave speed, and a crystal photonic device where the spheres made of silicium are too close to each other. In these cases, the locally refined meshes are a must for the accuracy of the approximated solution and the and the obtained numerical results demonstrate that our methods are efficient in terms of accuracy and CPU time metrics.obtained numerical results demonstrate that our methods are efficient in terms of accuracy and CPU time metrics
17
Engerroff, Juliano Assis Baron. "Obtenção via HDDR de pós nanocristalinos anisotrópicos à base de Nd-Fe-B." reponame:Repositório Institucional da UFSC, 2015. https://repositorio.ufsc.br/xmlui/handle/123456789/162585.
Full textAbstract:
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Ciência e Engenharia de Materiais, Florianópolis, 2015.Made available in DSpace on 2016-05-24T17:24:09Z (GMT). No. of bitstreams: 1 338942.pdf: 2648527 bytes, checksum: cb886767d486111772a926000df5ded9 (MD5) Previous issue date: 2015
O mercado de Ãmãs permanentes para aplicações de alto desempenho é hoje dominado pelos Ãmãs à base de terras raras (TR), como os Ãmãs de Nd-Fe-B. Neste contexto, uma das técnicas mais promissoras atualmente para obtenção de pós para Ãmãs compósitos é o processo d-HDDR (hidrogenação-desproporção-dessorção-recombinação, d = dinâmico), tratamento este realizado a alta temperatura sob atmosfera de hidrogênio a fim de promover o endurecimento magnético pelo refinamento da microestrutura, além de induzir textura magnética que, por consequência, maximiza o valor de produto de energia máximo. O presente trabalho tem como foco o estudo do processo d-HDDR aplicado a uma liga à base de Nd-Fe-B da classe comercial N42 para obtenção de pós nanocristalinos próprios para preparação de Ãmãs anisotrópicos. Sendo assim, elaborou-se um ciclo próprio de d-HDDR de referência e, a partir do mesmo, determinou-se as influências das seguintes variáveis: tempo de patamar para desproporção; tempo de patamar para recombinação final e temperatura de patamar para desproporção e recombinação. A caracterização magnética das amostras se deu por meio de um histeresÃgrafo. Já a microestrutura foi caracterizada via difração de raios X e microscopia eletrônica de varredura com emissão de campo. Os resultados mostraram que o processo d-HDDR estudado foi efetivo para obtenção de pós nanocristalinos com tamanho de grão de aproximadamente 300 nm e com grau de alinhamento de 80%. Para os intervalos de tempo de patamar de desproporção analisados, não há mudanças significativas dos valores de propriedades magnéticas quando comparados aos valores de referência, mantendo-se em Br ? 1,07 T, Hcj ? 700 kA/m e (BH)max ? 75 kJ/m³. Já para diferentes intervalos de tempo de patamar para recombinação final, ocorrem mudanças significativas dos valores de propriedades magnéticas, havendo um patamar de valores máximos em intervalos próximos ao de referência, onde Br ? 1,1 T, Hcj ? 700 kA/m e (BH)max ? 85 kJ/m³. Considerando as diferentes temperaturas de patamar para desproporção e recombinação avaliadas, os máximos valores de propriedades magnéticas atingidos foram: Br ? 1,05 T, Hcj ? 700 kA/m e (BH)max ? 80 kJ/m³.
Abstract : Rare earth-based magnets, e.g. Nd-Fe-B, now dominate the market of permanent magnets used for high performance applications. In this regard, one of the most promising techniques is currently the so called d-HDDR process (hydrogenation-disproportionation-desorption-recombination, d = dynamic), which includes a set of high temperature treatments under hydrogen atmosphere, in order to ensure magnetic hardening by microestrutural refinement and induce magnetic texture, whose consequently maximize maximum energy product value. This work focuses on the study of d-HDDR process applied to Nd-Fe-B-based alloy of N42 commercial class in order to obtain nanocrystalline powders, proper for anisotropic magnets fabrication. Therefore, it was prepared a proprietary d-HDDR cycle in which the following variables were studied: holding time for disproportionation; holding time for final recombination and disproportionation-recombination temperature. Magnetic characterization of the samples was carried out by means of a histeresigraph, whereas the formed phases were characterized via X-ray diffraction and the microstructure by scanning electron microscopy. Results showed that d-HDDR process was effective for obtaining anisotropic powders with grain size of approximately 300 nm and alignment degree of 80%. For the studied interval of holding time for disproportionation, no significant change of the magnetic values occurred if compared to the reference cycle, with values of Br ? 1.07 T, Hcj ? 700 kA/m e (BH)max ? 75 kJ/m³. However, for different time intervals in final recombination, there are significant changes in the values of magnetic properties, with a plateau of maximum values near the reference range, in which Br ? 1.1 T, Hcj ? 700 kA/m e (BH)max ? 85 kJ/m³. Regarding the different studied temperatures for disproportionation and recombination, the maximum values of magnetic properties achieved were Br ? 1.05 T, Hcj ? 700 kA/m and (BH)max ? 80 kJ/m³.
18
Bollero, Real Alberto. "Isotropic nanocrystalline (Nd,Pr)(Fe,Co)B permanent magnets." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2003. http://nbn-resolving.de/urn:nbn:de:swb:14-1069758225796-19366.
Full textAbstract:
Nanokristalline Permanentmagnete zeigen ungewöhnliche magnetische Eigenschaften aufgrund von Oberflächen- und Grenzflächeneffekten, die verschieden von denen massiver oder mikrokristalliner Materialien sind. Diese Arbeit zeigt Ergebnisse einer systematischen Untersuchung der Beziehung zwischen Mikrostruktur und magnetischen Eigenschaften von isotropen nanokristallinen (Nd,Pr)(Fe,Co)B-Permanentmagneten. Hochkoerzitive Magnete vom Typ (Nd,Pr)FeB wurden durch hochenergetisches Mahlen in der Kugelmühle oder Rascherstarrung hergestellt. Der Einfluss geringer Mengen von Zusätzen wie Dy und Zr und die Substitution von Nd durch Pr auf die magnetischen Eigenschaften wird dargestellt. Weiterhin wurde eine Einschätzung des Warmumformverhaltens dieser Materialien durchgeführt. Hochenergetisches Kugelmahlen einer Legierung mit der Anfangszusammensetzung Pr9Nd3Dy1Fe72Co8B6.9Zr0.1 führte, nach Glühbehandlung, zu fast einphasigem Magnetpulver mit einem maximalen Energieprodukt von (BH)max~140 kJm-3. Das hochenergetische Kugelmahlen wurde zu einer sehr vielseitigen Technik zur Herstellung hochleistungsfähiger Nanokompositmagnete weiterentwickelt. Das Zulegieren unterschiedlicher Anteile von weichmagnetischem alpha-Fe ist damit sehr effektiv möglich. Der Zusatz von 25 Gew.-% alpha-Fe führt zu einem hohen (BH)max=178kJm-3. Dies wird auf eine sehr effektive Austauschkopplung zwischen den hart- und weichmagnetischen Phasen zurückgeführt. Die Natur der intergranularen Wechselwirkungen kann durch die Wohlfarth´sche Remanenzanalyse (?deltaJ-plot¡§) beschrieben werden. Im speziellen wurden deltaJ-Diagramme für verschiedene (i) alpha-Fe Gehalte, (ii) Korngrößen und (iii) Austauschlängen erstellt. Es konnte gezeigt werden, dass in den Nanokompositmagneten auf Pr-Basis keine Spinumorientierung auftritt. Abschließend zeigt die Arbeit die Möglichkeit der Nutzung einer mechanisch aktivierten Gas-Festkörper-Reaktion auf, mit der eine sehr feinkörnige Mikrostruktur erhalten wird. Die Untersuchungen wurden mit stöchiometrischen Nd2(Fe1-xCox)14B-Legierungen begonnen (x=0-1). Die Verbindungen wurden unter höheren Wasserstoffdrücken und Temperaturen gemahlen, wodurch sie zu NdH2+delta und krz-(Fe,Co) (x=0-0.75) oder kfz-Co (x=1) entmischt wurden. Die Korngrößen des rekombinierten Nd2(Co,Fe)14B-Materials liegen im Bereich von 40-50 nmNanocrystalline permanent magnets present unusual magnetic properties because of surface/interface effects different from those of bulk or microcrystalline materials. This work presents results of a systematic investigation of the relationship between microstructure and magnetic properties in isotropic nanocrystalline (Nd,Pr)(Fe,Co)B permanent magnets. Highly coercive (Nd,Pr)FeB-type magnets have been produced using high energy ball milling and melt-spinning. The influence of small amounts of additives, Dy and Zr, and the substitution of Nd by Pr on the microstructural and magnetic properties are shown. An assessment of the hot deformation behaviour has been carried out. Intensive milling of an alloy with starting composition Pr9Nd3Dy1Fe72Co8B6.9Zr0.1 yields, after annealing treatment, nearly single-phase magnet powders with a maximum energy product (BH)max?î140kJm-3. Co has a beneficial effect on the intrinsic magnetic properties but also on the microstructure, with a mean grain size of 20nm. Intensive milling is used to produce high-performance nanocomposite magnets by blending this latter alloy with different fractions of soft magnetic alfa-Fe. Addition of 25wt.% alfa-Fe leads to a high (BH)max=178 kJm-3 due to an effective exchange-coupling between the hard and the soft magnetic phases. The intergrain interactions between the crystallites of the nanocomposite structure are analysed. Demagnetisation recoil loops of the nanocomposite magnets show relatively open minor loops due to the exchange-spring mechanism. Information about the intergrain interactions during demagnetisation are obtained by plotting the deviation of the demagnetising remanence from the Wohlfarth-model (¡§deltaJ-plot¡¨). Exchange-coupling phenomena are studied by analysing the evolution of the corresponding deltaJ values when varying (i) the alfa-Fe content, (ii) the annealing temperature, i.e. the grain size and (iii) the measurement temperature. Low temperature measurements do not reveal any sign of spin reorientation for these Pr-based nanocomposite magnets. The work concludes showing the possibility of using a mechanically activated gas-solid reaction to obtain an effective grain refined microstructure starting from stoichiometric Nd2(Fe1-xCox)14B alloys (x=0-1). These compounds were milled under enhanced hydrogen pressure and temperature leading to their disproportionation into NdH2+delta and bcc-(Fe,Co) (x=0-0.75) or fcc-Co (x=1). Grain sizes of recombined Nd2(Fe,Co)14B materials were found to be 40-50nm
19
Jamal, Fernando Galvanin. "Avaliação da precisão da declividade da técnica de perfuração direcional horizontal para instalações de redes de esgoto." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-10102008-091541/.
Full textAbstract:
O presente trabalho está focado no método de perfuração direcional horizontal (HDD) para instalação de redes de esgoto gravitacional. Descrevem-se os resultados de diferentes técnicas com o objetivo de se atingir a exigência de declividade. Para tanto foram executados 4 furos experimentais simulando trechos daquelas redes, com extensão de 30 m e tubulação de PEAD com diâmetro externo de 125 mm. Estas instalações foram executadas na cidade de São Carlos, Brasil, em um solo classificado granulometricamente como uma areia argilosa. Para cada uma das 4 instalações, adotou-se um processo construtivo diferenciado. Esta diferenciação se deu a partir do diâmetro do alargador adotado, do número de passadas do mesmo e da execução de furos verticais para alívio de pressão no espaço anelar assim como medidas diretas de profundidade do furo piloto. Após a instalação dos dutos foram realizadas medidas altimétricas no interior dos mesmos possibilitando avaliar quantitativamente os resultados obtidos. Estes resultados indicam que ainda é necessário refinar a técnica de perfuração direcional para a execução das redes de esgoto. Entretanto é possível observar que as variações empregadas na execução de cada um dos furos conduzem a um caminho de melhoria nos resultados obtidos. Esta melhoria pode ser observada nos furos onde o alargador adotado apresentava menor diâmetro conduzindo a menores desvios na posição final do duto. Salientam-se também os benéficos resultados da execução dos furos verticais que conduziram a menores pressões no espaço anelar assim como possibilitaram medidas altimétricas diretas da posição do furo piloto. Desta forma, é provável que com um maior número de experimentos e incrementos tecnológicos se atinja o objetivo final, ou seja, executar redes de esgoto gravitacional com declividade constante e baixa. Em paralelo nas instalações executadas foram realizados testes para avaliação da precisão e acurácia do sistema de navegação responsável pelo fornecimento de informações de posição e temperatura da ferramenta de corte durante a execução do furo piloto. Este trabalho contempla ainda, a elaboração de uma nova solução para as instalações de esgoto executadas através do HDD. Esta solução propõe a aplicação de um esforço de tração a um elemento externo, uma geogrelha que envolve a tubulação, visando posicionar a mesma em declividade constante. Face a seu caráter inovador foram desenvolvidos equipamentos e procedimentos de ensaio de laboratório, para avaliar a aplicabilidade da solução na práticaThe present work is focused on the horizontal directional drilling (HDD) method to install gravity sewers. The results of different techniques are described intending to meet the demands of gradient. Therefore, 4 experimental pilot bores were drilled simulating a section of those structures extending 30 m with HDPE pipelines of 125 mm external diameter. Those installations were engineered in the city of São Carlos, Brazil, in a clayey sand. For each of the 4 installations a distinct constructive process was adopted. Such characteristic was on account of the diameter of the selected reamer, the number of reamer steps and the vertical drills performed to relieve the pressure in the annular space, as well as the direct depth measurements of the pilot hole. After installing the pipes, altimetric measurements were performed inside them, hence enabling to quantitatively assess the obtained results. These results indicate the need to further refine the directional drilling technique for sanitary sewers. Yet it can be seen that the employed variations for each of the holes lead to an improved course of action with the observed results. Such improvement is perceived in the holes where the selected reamer had a smaller diameter, hence allowing for less displacement in the pipes final position. Also emphasized are the resulting benefits of the vertical drills that lead to less pressure in the annular space, as well as enabling altimetric measurements of the pilot hole position. Thus, it is presumed that with further experiments and technological developments the final objective is reached, meaning, putting into effect constant and low level gradient sewer networks. Tests for precision and accuracy assessment of the tracking system were also performed in each tube installed. The tracking system is responsible for providing information related to position and temperature of the drill head during the drilling operation. The steps for the development of a new HDD solution for sewer installation are presented. The idea is based on the application of a tensile force to an element external to the product, aiming at attaining a constant gradient. Equipments and procedures developed for this new technique are described.
20
Ferreira, Eliner Affonso. "Estudo das propriedades magnéticas e da microestrutura em ímãs permanentes à base de Pr-Fe-B-Co-Nb obtidos pelo processo HD e HDDR." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-18082009-162039/.
Full textAbstract:
Ímãs sinterizados foram produzidos utilizando o pó obtido pelo processo de Hidrogenação, Desproporção, Dessorção e Recombinação (Processo HDDR). O processo HDDR na produção de ímãs sinterizados foi adotado visando uma redução no tempo de moagem e investigar seu efeito nas propriedades magnéticas e na microestrutura. As ligas utilizadas nesse trabalho apresentaram a seguinte composição: Pr14FebalCoxB6Nb0,1 (x= 0; 4; 8; 10; 12; 16) e Pr20,5Fe72,5B5Cu2,0 (utilizada como aditivo de sinterização). O pó HDDR foi utilizado para produzir ímãs sinterizados com uma mistura dessas ligas (liga principal + aditivo), nas seguintes proporções: 80 % em peso da liga principal e 20% em peso do aditivo de sinterização (Pr20,5Fe72,5B5Cu2,0). O processo de decrepitação por hidrogênio (Processo HD) na produção de ímãs também foi utilizado nesse trabalho para efeito de comparação (tempos de moagem: 20, 15, 10 e 5 horas). A temperatura e o tempo de sinterização foram mantidos constantes para todos os ímãs (1050 º C por 60 minutos). O ímã sinterizado produzido pelo processo HD apresentou melhor remanência (1220 mT).Esse ímã foi fabricado com a liga Pr14Fe75,9B6Co4Nb0,1 utilizando um tempo de 20 horas de moagem. A melhor coercividade intrínseca foi obtida com a liga Pr14Fe75,9B6Co4Nb0,1 em ambos os processos, de 1020 mT para o processo D (5 horas de moagem) e de 1190 mT para o processo HD (20 horas de moagem). As microestruturas dos ímãs permanentes foram analisadas por microscopia eletrônica de varredura (MEV) e por dispersão de energia de raios-X (EDS).Sintered magnets have been produced with powder obtained using the hydrogenation, disproportionation, desorption and recombination (HDDR) process. The HDDR process for the production of the sintered magnets has been adopted in an attempt to reduce the milling time and to investigate its effect on the magnetic properties and microstructure. Commercial cast ingot alloys based on the compositions Pr14Fe75.9CoxB6Nb0.1 (x = 0; 4; 8; 10; 12; 16) and Pr20.5Fe72.5B5Cu2.0 (sintering aid) have been employed in this investigation. The HDDR powder was used to produce sintered magnets with a mixture of these alloys (alloy main + sintering aid), in the following proportion: 80%wt of the main alloy and 20%wt of the sintering aid. Standard hydrogen decrepitation (HD) magnets have also been included in this work for a comparison (milling time: 20, 15, 10, 5 hours). The sintering temperature and time were kept constant for all magnets (1050ºC for 1 hour). The sintered magnet produced using the process HD exhibited the best remanence (1220 mT). It was prepared with the Pr14Fe67.9Co4B6Nb0.1 alloy using a milling time of 20 hours. The best intrinsic coercivity was achieved with the Pr14Fe67.9Co4B6Nb0.1 magnet in both processes, namely: 1020 mT for the HDDR process with 5 hours of milling time and 1190 mT for the HD process with 20 hours of milling time. The microstructures of the permanent magnets have been investigated by scanning electron microscopy and energy dispersive X-ray analysis.
21
SILVA, SUELANNY C. da. "Estudo da influência da temperatura nas propriedades magnéticas e na microestrutura nos imãs permanentes à base de Pr-Fe-B-Nb-Co obtidos com hidrogênio." reponame:Repositório Institucional do IPEN, 2007. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11612.
Full textAbstract:
Made available in DSpace on 2014-10-09T12:53:51Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T13:58:57Z (GMT). No. of bitstreams: 0
Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
22
Li, Hai. "Storage Physics and Noise Mechanism in Heat-Assisted Magnetic Recording." Research Showcase @ CMU, 2016. http://repository.cmu.edu/dissertations/706.
Full textAbstract:
As cloud computing and massive-data machine learning are applied pervasively, ultra-high volume data storage serves as the foundation block. Every day, nearly 2.5 quintillion bytes (50000 GB/second in 2018) of data is created and stored. Hard Disk Drive (HDD) takes major part of this heavy duty. However, despite the amazing evolution of HDD technology during the past 50 years, the conventional Perpendicular Magnetic Recording (PMR), the state-of-the-art HDD technique, starts to have less momentum in increasing storage density because of the recording trilemma. To overcome this, Heat-Assisted Magnetic Recording (HAMR) was initially proposed in 1990s. With years of advancement, recent industrial demos have shown the potential of HAMR to actually break the theoretical limit of PMR. However, to fully take advantage of HAMR and realize the commercialization, there are still quite a few technical challenges, which motivated this thesis work. Via thermal coupled micromagnetic simulation based upon Landau-Lifshitz-Bloch (LLB) equation, the entire dynamic recording process has been studied systematically. The very fundamental recording physics theorem is established, which manages to elegantly interpret the previously conflicting experimental observations. The thermal induced field dependence of performance, due to incomplete switching and erase-after-write, is proposed for the first time and validated in industrial lab. The combinational effects form the ultimate physical limit of this technology. Meanwhile, this theorem predicts the novel noise origins, examples being Curie temperature distribution and temperature distribution, which are the key properties but ignored previously. To enhance performance, utilizations of higher thermal gradient, magnetically stiffer medium, optimal field etc. have been suggested based upon the theorem. Furthermore, a novel concept, Recording Time Window (RTW), has been proposed. It tightly correlates with performance and serves as a unified optimization standard, summarizing almost all primary parameters. After being validated via spin stand testing, the theorem has been applied to provide solutions for guiding medium design and relaxing the field and heating requirement. This helps solve the issues around writer limit and thermal reliability. Additionally, crosstrack varying field has been proposed to solve the well-known transition curvature issue, which may increase the storage density by 50%.
23
Xue, Dingchuan. "Electro-deposition of resin-modified water-based hydrophobic silane on HDG steel for corrosion protection." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1229010186.
Full text
24
Olivares, Nicole Michelle. "Accuracy of Wave Speeds Computed from the DPG and HDG Methods for Electromagnetic and Acoustic Waves." PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/2920.
Full textAbstract:
We study two finite element methods for solving time-harmonic electromagnetic and acoustic problems: the discontinuous Petrov-Galerkin (DPG) method and the hybrid discontinuous Galerkin (HDG) method.
The DPG method for the Helmholtz equation is studied using a test space normed by a modified graph norm. The modification scales one of the terms in the graph norm by an arbitrary positive scaling parameter. We find that, as the parameter approaches zero, better results are obtained, under some circumstances. A dispersion analysis on the multiple interacting stencils that form the DPG method shows that the discrete wavenumbers of the method are complex, explaining the numerically observed artificial dissipation in the computed wave approximations. Since the DPG method is a nonstandard least-squares Galerkin method, its performance is compared with a standard least-squares method having a similar stencil.
We study the HDG method for complex wavenumber cases and show how the HDG stabilization parameter must be chosen in relation to the wavenumber. We show that the commonly chosen HDG stabilization parameter values can give rise to singular systems for some complex wavenumbers. However, this failure is remedied if the real part of the stabilization parameter has the opposite sign of the imaginary part of the wavenumber. For real wavenumbers, results from a dispersion analysis for the Helmholtz case are presented. An asymptotic expansion of the dispersion relation, as the number of mesh elements per wave increase, reveal values of the stabilization parameter that asymptotically minimize the HDG wavenumber errors. Finally, a dispersion analysis of the mixed hybrid Raviart-Thomas method shows that its wavenumber errors are an order smaller than those of the HDG method.
We conclude by presenting some contributions to the development of software tools for using the DPG method and their application to a terahertz photonic structure. We attempt to simulate field enhancements recently observed in a novel arrangement of annular nanogaps.
25
Silva, Suelanny Carvalho da. "Estudo da influência da temperatura nas propriedades magnéticas e na microestrutura nos ímãs permanentes à base de Pr-Fe-B-Nb-Co obtidos com hidrogênio." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-24102011-104115/.
Full textAbstract:
Pós magnéticos foram produzidos utilizando o processo de hidrogenação, desproporção, dessorção e recombinação (HDDR). A primeira parte deste trabalho envolveu o estudo do efeito da adição de Co na liga Pr14FebalCoxB6Nb0.1 (x= 0, 4, 8, 10, 12, 16) variando a de temperatura de dessorção/ recombinação de 800° a 900°C, com o objetivo de otimização do tratamento HDDR. A liga Pr14Fe80B6 foi utilizada como padrão. As ligas foram tratadas termicamente a 1100°C por 20 horas para eliminação do Fe- exixtente na liga em estado bruto de fusão. A temperatura de dessorção/ recombinação afetou a microestrutura e as propriedades magnéticas dos ímãs moldados com polímeros. A liga com baixa adição de cobalto (4 at.%) exigiu a temperatura de reação mais alta (880°C) entre os demais ímãs. As temperaturas ótimas para as ligas com 8 at.% Co e 10 at.% Co foram 840°C e 820°C, respectivamente. Ligas com altas concentrações de cobalto (12 at.% and 16 at.%) foram processadas a 840°C. A temperatura de dessorção/ recombinação que apresentou alta anisotropia nas ligas Pr14Fe80B6 e Pr14Fe79,9B6Nb0,1 foi de 820°C. O ímã que apresentou melhor remanência (862mT) foi processado com a liga Pr14Fe67,9Co12B6Nb0,1. Cada liga apresentou uma temperatura de reação otimizada e exibiu uma microestrutura particular, de acordo com a composição. A segunda parte deste trabalho envolveu a caracterização, dos pós HDDR de Pr14Fe80B6, que foram analisadas por difração de raios X com fonte síncrotron para a identificação e quantificação de fases cristalinas, e ainda para a determinação do tamanho médio de cristalitos da fase principal. A microscopia eletrônica de varredura (MEV) foi utilizada para revelar a morfologia dos pós HDDR.Fine magnetic powders were produced using the hydrogenation disproportionation desorption and recombination (HDDR) process. The first stage in this work involved an investigation of the effect of the Co content and range of desorption/ recombination temperatures between 800 and 900°C with the purpose of optimizing the HDDR treatment for Pr14Fe80B6 and Pr14FebalCoxB6Nb0,1 (x= 0, 4, 8, 10, 12, 16) alloys. The cast alloys were annealed at 1100°C for 20 hours for homogenization. The processing temperature (desorption/ recombination) affected the microstructure and magnetic properties of the bonded magnets. The alloy with low cobalt content (4 at.%) required the highest reaction temperature (880°C) to yield anisotropic bonded magnets. The optimum temperature for alloys with 8 at.% Co and 10 at.% Co were 840°C and 820°C, respectively. Alloys with high cobalt content (12 at.% and 16 at.%) were processed at 840°C. The optimum desorption temperature for achieving high anisotropy for Pr14Fe80B6 and Pr14Fe79,9B6Nb0,1 was 820°C. The best remanence (862mT) was achieved with the Pr14Fe67,9B6Co12Nb0,1 magnet, processed at 840°C. Each alloy required an optimum reaction temperature and exhibited a particular microstructure according to the composition. The second stage of the work involved the characterization, for each temperature, of the Pr14Fe80B6 HDDR powder processed using X-ray diffraction analysis. The samples of the HDDR material were studied by synchrotron radiation powder diffraction using the Rietveld method for cell refinement, phase quantification and crystallite sizes determination. Scanning electron microscopy (SEM) has also been employed to reveal the morphology of the HDDR powder.
26
Santos, Patricia Brissi. "Efeitos da adição de surfactante e moagem de alta velocidade em pós magnéticos à base de Pr-Fe-B obtidos via HDDR." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-26012012-145626/.
Full textAbstract:
Esse trabalho teve como objetivo verificar o efeito da adição do ácido oléico na moagem de alta velocidade/energia na obtenção de pós magnéticos em escala nanométricas da liga Pr12Fe65,9Co16B6Nb0,1. A primeira etapa deste trabalho, envolveu a obtenção de pós magnéticos por meio do processo de hidrogenação, desproporção, dessorção e recombinação (HDDR), utilizando a pressão de H2 de 930 mbar (hidrogenação e desproporção) e temperatura de dessorção e recombinação de 840 ºC. Inicialmente, os pós HDDR foram submetidos à moagem de alta velocidade/energia a 900 rpm, com variação do volume do meio de moagem (ciclohexano) sem adição de ácido oleico. Em seguida, os pós HDDR foram submetidos à moagem com adição de ácido oleico, variando o tempo de moagem. Após a moagem, foi realizado tratamento térmico dos pós a 700 ºC ou 800 ºC durante 30 min., com a finalidade de cristalização do pó. Foi verificado que, a utilização de 6,6 ml de ciclohexano como meio de moagem e com adição de ácido oleico há uma melhora na eficiência da moagem dos pós. Para adições de surfactante, de 0,02 a 0,05 ml e tempos de moagem até 360 minutos, não ocorre a aglomeração dos pós magnéticos no pote de moagem, obtendo acima de 90% de eficiência na moagem. A segunda etapa deste trabalho envolveu a caracterização dos pós magnéticos: utilizando magnetômetro de amostra vibrante, microscopia eletrônica de Varredura, microscopia eletrônica de transmissão e difração de raios-X. Os resultados obtidos mostraram que a adição de ácido oléico na moagem de alta velocidade/energia proporciona uma melhora nas propriedades magnéticas. Com a variação do tempo de moagem a fase Fe-α presente no pó HDDR apresenta diminuição no tamanho do cristalito (de 35 para ~ 10 nm) enquanto que, na fase Pr2Fe14B verifica-se menor grau de cristalinidade.This work verified the effect caused by adding the surfactant in the high speed/energy milling in order to obtain Pr12Fe65.9Co16B6Nb0.1 magnetic nanopowders. The first part of this work involved the magnetic powder obtainment through the process of hydrogenation, disproportionation, desorption and recombination (HDDR). The pressure of H2 during the hydrogenation and disproportion steps was 930 mbar and the temperature of desorption and recombination was 840 ºC. Initially, the HDDR powders were subjected a highspeed milling process at 900 rpm, with quantity variations of the milling medium (cyclohexane) and without the addition of oleic acid. Then, the HDDR powders were subjected to the milling process with the addition of oleic acid and with milling time variations. After the milling process, heat treatments of the powder were carried out at 700 °C or 800 °C for 30 minutes in order to obtain the crystallization of the powder. By performing the procedures, it was verified that the milling efficiency improved with the addition of 6.6 ml of cyclohexane as the milling medium and with the addition of oleic acid. It was determined that for the surfactant additions of 0.02 ml to 0.05 ml, with a milling time of up to 360 minutes, powder agglomeration does not occur in the milling pot and the milling efficiency is higher than 90%. The second stage of this work involved the magnetic powders characterization obtained by using vibrating sample magnetometer, scanning electron microscopy, transmission electron microscopy and X-ray diffraction. Through the characterizations it was found that the powders magnetic properties improved when the addition of oleic acid in a high-speed /energy milling occurred. It was also verified that the α-Fe phase, present in the powder, shows a crystallite size decrease (from 35 nm to ~ 10 nm) when the time milling variation occurred; meanwhile, the crystallinity degree was lower in the Pr2Fe14B phase when the time milling variations was carried out.
27
SANTOS, PATRICIA B. "Efeitos da adição de surfactante e moagem de alta velocidade em pós magnéticos à base de Pr-Fe-B obtidos via HDDR." reponame:Repositório Institucional do IPEN, 2011. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10044.
Full textAbstract:
Made available in DSpace on 2014-10-09T12:34:08Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:06:40Z (GMT). No. of bitstreams: 0
Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
28
Carson, Hugh Alexander. "A priori analysis of global and local output error estimates for CG, DG and HDG finite element discretizations." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105608.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 103-105).
In this thesis, a priori convergence estimates are developed for outputs, output error estimates, and localizations of output error estimates for Galerkin finite element methods. Specifically, Continuous Galerkin (CG), Discontinuous Galerkin (DG), and Hybridized DG (HDG) methods are analyzed for the Poisson problem. A mixed formulation for DG output error estimation is proposed with improved convergence rates relative to the common approach utilizing statically condensed, p-dependent lifting operators. The HDG output error estimates are new and include the impact of stabilization. Comparisons to numerical results demonstrate (1) the sharpness of the estimates and (2) that the HDG estimates are approximately an order of magnitude more accurate than CG and DG.
by Hugh Alexander Carson.
S.M.
29
Elander, Per, and Dennis Thai. "Datalagring : en komparativ stude av datalagringslösningar." Thesis, Högskolan Kristianstad, Sektionen för hälsa och samhälle, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hkr:diva-15554.
Full textAbstract:
Sedan företag började använda sig av internet som ett verktyg för sitt arbete har bekymmer uppstått som de inte haft tidigare, som hur företagsdata ska lagras, vad för utrustning som är bäst för deras behov. Genomförandet av arbetet delades in i tre delar, där det första var att ta reda på vilka olika datalagringslösningar som fanns och användes i servermiljöer. Detta gjordes via litteraturstudier. Den andra delen var att intervjua kundföretag om deras lagringslösningar samt intervjua leverantörer av datalagringslösningar med ett antal frågor som berörde deras datalagringlösning(ar), rekommendationer och framtidsutsikten för datalagring. Den tredje och slutgiltiga delen var att skriva samman analysen över den information som tillförskaffats och de iakttagelser som gjorts. Resultatet av intervjuerna visade på flera pålitliga och snabba alternativ för datalagring som kunder använde och leverantörer sålde. Lösningar som användes och levererades var NAS(Network Attached Storage), molnlagring av data och SAN(Storage Area Network). Vid genomförande av analysen togs både intervjumaterialet och litteraturmaterialet i beaktning för att kunna komma fram till adekvata slutsatser. Syftet med slutsatserna var att kunna ge ett bra svar på de frågor i frågeställningen som låg till grund för examensarbetet. Vad man har kommit fram till är att det finns inget bra svar för vilken lösning är bäst utan att olika lösningar är anpassad till olika syften och behov.
30
Frydryszak, Andrzej. "Ocena zasadności budowy podziemnych przewodów metodą przewiertów sterowanych." Rozprawa doktorska, [Nakł.aut.], 2005. http://dlibra.utp.edu.pl/Content/181.
Full text
31
OLIVEIRA, MARA C. L. de. "Preparacao de imas HDDR e ligas de PrFe-Co-B-Nb-M (M=Al,P,Cu,Ga e/ou Gd) e caracterizacao de suas propriedades magneticas e resistencia a corrosao." reponame:Repositório Institucional do IPEN, 2009. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11783.
Full textAbstract:
Made available in DSpace on 2014-10-09T12:55:46Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:05:18Z (GMT). No. of bitstreams: 0
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
32
BARBOSA, LUZINETE P. "Estudo das propriedades e microestrutura de ímãs permanentes de Pr-Fe-B-(Co-Nb) preparados pelo processo de hidrogenação, desproporção, dessorção e recombinação (HDDR)." reponame:Repositório Institucional do IPEN, 2005. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11280.
Full textAbstract:
Made available in DSpace on 2014-10-09T12:50:14Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:02:40Z (GMT). No. of bitstreams: 1 10553.pdf: 9807833 bytes, checksum: fcd7e02a22a70e9ee79a1dcccaf7f496 (MD5)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
33
FERREIRA, ELINER A. "Estudo das propriedades magnéticas e da microestrutura em imãs permanentes à base de Pr-Fe-B-Co-Nd obtidos pelos processos HD e HDDR." reponame:Repositório Institucional do IPEN, 2008. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11694.
Full textAbstract:
Made available in DSpace on 2014-10-09T12:54:50Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:06:59Z (GMT). No. of bitstreams: 0
Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN/CNEN-SP
34
Hattasingh, Thanyaporn. "Bridging multinational companies intra-firm technology transfer and host country institutional factors- the cases of Thailand's HDD and IC sectors." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489635.
Full textAbstract:
Intra-firm technology transfer by MNCs is viewed as important for a FDI-led industrialising country like Thailand. Although Thailand has attracted to a high level of FDl, MNC technology transfer to Thailand is still at a very limited level. The aim of this thesis is to explore the muUial relationships between MNC intra-firm technology transfer and the host mtry's institutional factors in the context Thai HDD and IC sectors.
35
Galego, Eguiberto. "Estudo de ligas e ímãs preparados pelo processo hidrogenação, desproporção, dessorção e recombinação (HDDR) à base de Pr-Fe-B com adição de dopantes elementos de liga." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-09062008-153410/.
Full textAbstract:
A adição de elementos dopantes e elementos de liga aos magnetos permanentes policristalinos à base de terras raras tem como objetivo a melhora das propriedades magnéticas. Neste trabalho estudou-se a adição de 0,1% at. dos elementos: Ti, V, Cr, Ni, Zr, Nb ou Mo na composição Pr14FebalCo16B6 ; as adições de 0,1 % at., 0,3 % at. e 0,5 % at. dos elementos Al, Si, P, Cu ou Ga na composição Pr14FebalCo16B6Nb0,1 ; e a variação de cobalto de 0 % at. até 16 % at. ao sistema Pr2Fe14-xCoxB. Através de processo HDDR (hidrogenação, desproporção, dessorção e recombinação) obteve-se pós com tamanho de grão da ordem de 200 a 300 nm para quase todas as composições estudadas. Os pós foram utilizados para a confecção de magnetos consolidados por cianoacrilato de baixa viscosidade. De maneira geral, a adição destes dopantes resultou no aumento ou diminuição da remanência e da coercividade intrínseca da liga quando comparadas com os valores obtidos para magnetos de referência sem adição de dopantes. Porém, não foram observadas correlações entre as composições estudadas quer quanto ao número atômico ou em relação à concentração do elemento adicionado. Os resultados obtidos com a adição de Al, Si, P, Ti, V, Cr, Ni, Cu, Ga, Zr ou Nb indicaram que alguns elementos atuam como substituintes do átomo de ferro na estrutura cristalina da fase magnética dura ou como modificador da microestrutura da liga. A determinação dos parâmetros da célula unitária, as posições atômicas, os sítios de substituição do ferro pelo cobalto (fator de ocupação) para a sistema Pr2Fe14-xCoxB foi realizada pelo refinamento dos padrões de pó obtidos por difração de raios X pelo método de Rietveld. Estes dados foram utilizados no cálculo das iii propriedades magnéticas por ab-initio com base na teoria do funcional densidade empregando o método LAPW (linearized augmented plane wave). A comparação dos resultados teórico e experimental apresentou forte concordância mostrando que este método é importante para o estudo da adição de dopantes ao sistema Pr-Fe-Co-B.Estudo de Ligas e Ímãs Preparados pelo Processo Hidrogenação, Desproporção, Dessorção e Recombinação (HDDR) à Base de Pr-Fe-B com Adição de Dopantes e Elementos de Liga Eguiberto Galego RESUMO A adição de elementos dopantes e elementos de liga aos magnetos permanentes policristalinos à base de terras raras tem como objetivo a melhora das propriedades magnéticas. Neste trabalho estudou-se a adição de 0,1% at. dos elementos: Ti, V, Cr, Ni, Zr, Nb ou Mo na composição Pr14FebalCo16B6 ; as adições de 0,1 % at., 0,3 % at. e 0,5 % at. dos elementos Al, Si, P, Cu ou Ga na composição Pr14FebalCo16B6Nb0,1 ; e a variação de cobalto de 0 % at. até 16 % at. ao sistema Pr2Fe14-xCoxB. Através de processo HDDR (hidrogenação, desproporção, dessorção e recombinação) obteve-se pós com tamanho de grão da ordem de 200 a 300 nm para quase todas as composições estudadas. Os pós foram utilizados para a confecção de magnetos consolidados por cianoacrilato de baixa viscosidade. De maneira geral, a adição destes dopantes resultou no aumento ou diminuição da remanência e da coercividade intrínseca da liga quando comparadas com os valores obtidos para magnetos de referência sem adição de dopantes. Porém, não foram observadas correlações entre as composições estudadas quer quanto ao número atômico ou em relação à concentração do elemento adicionado. Os resultados obtidos com a adição de Al, Si, P, Ti, V, Cr, Ni, Cu, Ga, Zr ou Nb indicaram que alguns elementos atuam como substituintes do átomo de ferro na estrutura cristalina da fase magnética dura ou como modificador da microestrutura da liga. A determinação dos parâmetros da célula unitária, as posições atômicas, os sítios de substituição do ferro pelo cobalto (fator de ocupação) para a sistema Pr2Fe14-xCoxB foi realizada pelo refinamento dos padrões de pó obtidos por difração de raios X pelo método de Rietveld. Estes dados foram utilizados no cálculo das iii propriedades magnéticas por ab-initio com base na teoria do funcional densidade empregando o método LAPW (linearized augmented plane wave). A comparação dos resultados teórico e experimental apresentou forte concordância mostrando que este método é importante para o estudo da adição de dopantes ao sistema Pr-Fe-Co-B.
36
GALEGO, EGUIBERTO. "Estudo de ligas e imás preparados pelo processo hidrogenação, desproporção, dessorção e recombinação (HDDR) a base de Pr-Fe-B com adição de dopantes e elementos de liga." reponame:Repositório Institucional do IPEN, 2008. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11611.
Full textAbstract:
Made available in DSpace on 2014-10-09T12:53:50Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T13:58:58Z (GMT). No. of bitstreams: 0
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
37
Liesert, Silke. "Analyse physico-chimique des paramètres du développement d'une microstructure coercitive et anisotrope dans des poudres pour aimants liés puissants par application du procédé HDDR au néodyme-fer-bore." Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10027.
Full textAbstract:
Des poudres fortement coercitives ont ete elaborees par procede hddr (hydrogenation-disproportionation-desorbtion-recombinaition) a partir de precurseurs nd-fe-b. Une systematique d'etudes in-situ (diffraction neutronique, mesures thermomagnetiques, analyse thermique differentielle) nous a conduit a un bon niveau de connaissance des mecanismes essentiels pour la mise en place d'une microstructure performante. Une anisotropie par texturation a ete ainsi developpee a partir de trois demarches differentes : 1. La premiere methode s'applique a l'etape de decomposition (hddr) du neodyme-fer-bore. Au dela d'une certaine temperature la reaction de decomposition est tres rapide. Mais elle peut etre controlee soit par adjonction de zirconium, soit en utilisant un alliage ternaire et en operant a temperature moderee. Ainsi il a ete possible de conserver des germes de nd#2fe#1#4b apres l'etape de decomposition, qui reagissent au cours de la recristallisation comme centres de nucleation (mr# / mr#/#/ = 0. 5 et hc = 6. 5koe). 2. La deuxieme methode consiste a appliquer un champ magnetique intense au cours de l'etape de recristallisation (hddr) pour induire une rotation des cristallites de nd#2fe#1#4b lors de leur formation dans une phase intergranulaire nd-cu. Il importe que cette phase intergranulaire soit liquide et que les cristallites de nd#2fe#1#4b presentent une taille minimale (mr# / mr#/#/ = 0. 6 et hc = 7koe). 3. La troisieme methode consiste en l'application a chaud d'une forte contrainte (die-upsetting) sur une pastille frittee de poudre-hddr fortement coercitive. L'etablissement d'une microstructure anisotrope a pu etre realise apres controle de certains parametres liees a la plasticite de l'alliage (taille des cristallites de nd#2fe#1#4b, quantite de phase intergranulaire. . . ) (mr# / mr#/#/ = 0. 6 et hc = 9. 5koe).
38
Roßbach, Stefan [Verfasser]. "Untersuchungen zur Reduzierung der Zugkräfte beim Einziehen von Rohrleitungen mittels Schwingungstechnologie : ein innovativer Beitrag zur Reduzierung des Baurisikos bei HDD-Vorhaben / vorgelegt von Stefan Roßbach." [Clausthal-Zellerfeld] : [Univ.-Bibliothek], 2008. http://d-nb.info/992514770/34.
Full text
39
Sládek, Petr. "Disková pole RAID a jejich budoucnost v éře SSD." Master's thesis, Vysoká škola ekonomická v Praze, 2012. http://www.nusl.cz/ntk/nusl-124667.
Full textAbstract:
The thesis aims at verification of using emerging Solid-State drives in disk arrays. The advent of SSD disks caused a small revolution in area of data storage, because the growth performance of hard drives has been slow compared to other PC components. But an entirely different principle of operation could mean compatibility problems between SSD and related technologies, such as RAID. This thesis aims at analyzing all the relevant technologies, mainly HDD, SSD and RAID. To achieve this objective, information from literature, articles and other appropriate sources will be used. Other objectives of this thesis are to determine how much are the SSDs suitable for use in the disk array, because low performance RAID controllers or different principles of operation could limit their efficiency. This question should be answered by submission of selected types of storage arrays to synthetic and practical tests of performance. The final goal is to use financial analysis of the test solutions as a shared file storage. Today, remote access to data is used by a wide range of job positions. Slow storage could mean inefficient use of working time and therefore unnecessary financial costs. The goal of my work is primarily to provide answers to the questions mentioned above. Currently it is very hard to find tests of more complex forms of disk arrays based on solid-state drives. This article can be also very useful for companies where fileservers are used to share user data. Based on the result of cost analysis, the company can then decide what type of storage is best for its purpose.
40
Oliveira, Mara Cristina Lopes de. "Preparação de ímas HDDR e ligas de Pr-Fe-Co-B-Nb-M (M=Al, P, Cu, Ga e/ou Gd) e caracterização de suas propriedades magnéticas e resistência à corrosão." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-21092009-103331/.
Full textAbstract:
O processo HDDR tem-se mostrado de grande interesse para a produção de ímãs à base de terras raras e polímeros. Apresenta vantagens comerciais quando comparado com os ímãs sinterizados convencionais, por exemplo, pela facilidade e menores custos de produção. Com o desenvolvimento de pós anisotrópicos, utilizando praseodímio, as expectativas em relação a este processo aumentam e, também, a necessidade de se estudar novas composições e adições. Neste trabalho, foram investigadas as propriedades magnéticas de ímãs moldados com resina, preparados com pós de ligas magnéticas de PrFeB, usando o processo HDDR. A liga magnética padrão utilizada foi a Pr14FebalCo16B6Nb0,1. Adições de elementos de liga como fósforo, cobre, alumínio, gálio e gadolíneo foram realizadas com o objetivo de melhorar as propriedades magnéticas do material padrão. A caracterização microestrutural dos ímãs foi realizada por microscopia óptica e MEV. A complexidade da microestrutura influencia o comportamento eletroquímico das ligas magnéticas. A literatura sobre este assunto é escassa. Assim, a resistência à corrosão das diferentes ligas preparadas ao longo do trabalho foi avaliada por espectroscopia de impedância eletroquímica e curvas de polarização potenciodinâmica. Foi estabelecida uma correlação entre as características microestruturais e o comportamento eletroquímico das ligas. Os resultados indicaram que adições de fósforo e alumínio em teores de até 1,0%p têm um efeito benéfico sobre as propriedades magnéticas e resistência à corrosão da liga padrão. A presença de cobre, por outro lado, diminui sensivelmente as propriedades magnéticas da liga padrão.HDDR process has attracted great interest for producing polymer- bonded rareearth based magnets. It presents commercial advantages when compared with conventional sintered magnets owing to easy and low cost manufacturing. With the development of anisotropic powders using praseodymium, the expectations about this process grow e also the need for studying new compositions and alloy additions. In this work the magnetic properties of polymer-bonded magnets prepared with PrFeB magnetic alloys using HDDR process have been studied. Pr14FebalCo16B6Nb0,1 was used as the reference alloy Phosphorus, copper, aluminium, galium and gadolynium additions have been performed to increase the magnetic properties of the reference alloy. The microstructural characterization of the magnets has been carried out through optical microscopy and SEM. The complex microsctructure influences the electrochemical behavior of the magnetic alloys. The literature about this subject is scarce. Thus, the corrosion resistance of the different alloys prepared during this work was evaluated using electrochemical impedance spectroscopy and potentiodynamic polarization curves. A correlation between the microstructural features and the electrochemical behavior of the alloys has been established. The results showed that phosphorus and aluminium additions up to 1.0wt% had a beneficial effect on the magnetic properties and corrosion resistance of the alloys. Copper additions, on the other hand, strongly diminished the magnetic properties of the reference alloy.
41
Ouarnoughi, Hamza. "Placement autonomique de machines virtuelles sur un système de stockage hybride dans un cloud IaaS." Thesis, Brest, 2017. http://www.theses.fr/2017BRES0055/document.
Full textAbstract:
Les opérateurs de cloud IaaS (Infrastructure as a Service) proposent à leurs clients des ressources virtualisées (CPU, stockage et réseau) sous forme de machines virtuelles (VM). L’explosion du marché du cloud les a contraints à optimiser très finement l’utilisation de leurs centres de données afin de proposer des services attractifs à moindre coût. En plus des investissements liés à l’achat des infrastructures et de leur coût d’utilisation, la consommation énergétique apparaît comme un point de dépense important (2% de la consommation mondiale) et en constante augmentation. Sa maîtrise représente pour ces opérateurs un levier très intéressant à exploiter. D’un point de vue technique, le contrôle de la consommation énergétique s’appuie essentiellement sur les méthodes de consolidation. Or la plupart d'entre elles ne prennent en compte que l’utilisation CPU des machines physiques (PM) pour le placement de VM. En effet, des études récentes ont montré que les systèmes de stockage et les E/S disque constituent une part considérable de la consommation énergétique d’un centre de données (entre 14% et 40%). Dans cette thèse nous introduisons un nouveau modèle autonomique d’optimisation de placement de VM inspiré de MAPE-K (Monitor, Analyze, Plan, Execute, Knowledge), et prenant en compte en plus du CPU, les E/S des VM ainsi que les systèmes de stockage associés. Ainsi, notre première contribution est relative au développement d’un outil de trace des E/S de VM multi-niveaux. Les traces collectées alimentent, dans l’étape Analyze, un modèle de coût étendu dont l’originalité consiste à prendre en compte le profil d’accès des VM, les caractéristiques du système de stockage, ainsi que les contraintes économiques de l’environnement cloud. Nous analysons par ailleurs les caractéristiques des deux principales classes de stockage, pour aboutir à un modèle hybride exploitant au mieux les avantages de chacune. En effet, les disques durs magnétiques (HDD) sont des supports de stockage à la fois énergivores et peu performants comparés aux unités de calcul. Néanmoins, leur prix par gigaoctet et leur longévité peuvent jouer en leur faveur. Contrairement aux HDD, les disques SSD à base de mémoire flash sont plus performants et consomment peu d’énergie. Leur prix élevé par gigaoctet et leur courte durée de vie (comparés aux HDD) représentent leurs contraintes majeures. L’étape Plan a donné lieu, d’une part, à une extension de l'outil de simulation CloudSim pour la prise en compte des E/S des VM, du caractère hybride du système de stockage, ainsi que la mise en oeuvre du modèle de coût proposé dans l'étape Analyze. Nous avons proposé d’autre part, plusieurs heuristiques se basant sur notre modèle de coût et que nous avons intégrées dans CloudSim. Nous montrons finalement que notre approche permet d’améliorer d’un facteur trois le coût de placement de VM obtenu par les approches existantesIaaS cloud providers offer virtualized resources (CPU, storage, and network) as Virtual Machines(VM). The growth and highly competitive nature of this economy has compelled them to optimize the use of their data centers, in order to offer attractive services at a lower cost. In addition to investments related to infrastructure purchase and cost of use, energy efficiency is a major point of expenditure (2% of world consumption) and is constantly increasing. Its control represents a vital opportunity. From a technical point of view, the control of energy consumption is mainly based on consolidation approaches. These approaches, which exclusively take into account the CPU use of physical machines (PM) for the VM placement, present however many drawbacks. Indeed, recent studies have shown that storage systems and disk I/O represent a significant part of the data center energy consumption (between 14% and 40%).In this thesis we propose a new autonomic model for VM placement optimization based on MAPEK (Monitor, Analyze, Plan, Execute, Knowledge) whereby in addition to CPU, VM I/O and related storage systems are considered. Our first contribution proposes a multilevel VM I/O tracer which overcomes the limitations of existing I/O monitoring tools. In the Analyze step, the collected I/O traces are introduced in a cost model which takes into account the VM I/O profile, the storage system characteristics, and the cloud environment constraints. We also analyze the complementarity between the two main storage classes, resulting in a hybrid storage model exploiting the advantages of each. Indeed, Hard Disk Drives (HDD) represent energy-intensive and inefficient devices compared to compute units. However, their low cost per gigabyte and their long lifetime may constitute positive arguments. Unlike HDD, flash-based Solid-State Disks (SSD) are more efficient and consume less power, but their high cost per gigabyte and their short lifetime (compared to HDD) represent major constraints. The Plan phase has initially resulted in an extension of CloudSim to take into account VM I/O, the hybrid nature of the storage system, as well as the implementation of the previously proposed cost model. Secondly, we proposed several heuristics based on our cost model, integrated and evaluated using CloudSim. Finally, we showed that our contribution improves existing approaches of VM placement optimization by a factor of three
42
Boman, Joel, Markus Forsmark, and Waldemar Schagerström. "Att presentera information i virtuell verklighet : En studie om var och hur information bör presenteras i virtuell verklighet vid användning av en fordonssimulator." Thesis, Umeå universitet, Institutionen för informatik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-135586.
Full textAbstract:
When talking about how to present information in virtual reality, the possibilities are countless, but there are also many problems surrounding the spatial location of the information. This study aims to examine where and how the instructions in a vehicle training simulator should be presented in a future implementation of the interface in virtual reality. To find this out, a gameplay was created in which four different placements of the instructions were made. Three options were based on earlier studies made by Smith (2015) and Jose (2016) and the fourth was based on the existing information in the vehicle training simulator. These gameplays were presented as a movie to a number of interviewees and followed up by questions after each movie. The interviewees were asked to give the movies three ratings from 1-5, valuing how they perceived the presentation of the instructions. To get further opinions, comments was collected from the interviewees throughout each session. In this two ways, we got answers to which of the four options the interviewees thought was best. The study showed that there were two options that stood out among the others and both were based on the concept of a head-up display, also known as a HUD. One was represented in the bottom of the windshield and the other one in the top. The result of which one of them who were perceived as best is too close to say, although the study is considered to have reached its goal, which was to help the developers on their way to a decision that will eventually be implemented.
43
Sherif, Ahmed. "Compact High-Order Accurate Scheme for Laminar Incompressible Two-Phase Flows." Electronic Thesis or Diss., Ecole centrale de Nantes, 2023. http://www.theses.fr/2023ECDN0004.
Full textAbstract:
L'objectif de cette thèse est de développer une méthode précise d'ordre élevé pour résoudre le problème d'écoulementlaminaire incompressible à deux phases. Trois tâches principales sont à accomplir. Premièrement, la méthode doit être stable en énergie, ce qui signifie que la condition sans divergence de l'équation de Navier-Stokes incompressible est satisfaite partout dans le domaine de calcul. Deuxièmement, les discontinuités locales apparaissant dans le champ d'écoulement diphasique doivent être capturées avec précision. Troisièmement, l'interface matérielle entre les deux fluides doit être représentée avec précision à chaque pas de temps. Dans ce travail, une nouvelle méthode Hybridizable Discontinuous Galerkin (HDG) est utilisée pour la discrétisation spatiale. Cette méthode hybride qui appartient à la famille des méthodes DG-FEM satisfait la condition sans divergence en introduisant des variables de trace de vitesse et de pression du même ordre plus une approximation de vitesse et de pression adaptée à l'intérieur des éléments. Deplus, les concepts de FEM eXtended (X-FEM) sont utilisés pour approximer les discontinuités dans le champ d'écoulement en enrichissant l'approximation FEM standard dans les éléments où deux fluides existent. Enfin, l'interface du matériau en mouvement entre les deux fluides est capturée à l'aide de la méthode Level-SetThe objective of this thesis is to develop a high-order accurate method to solve the two-phase incompressible laminar flowproblem. Three main tasks are to be achieved. First, the method has to be energy-stable meaning that the divergence-free condition of the incompressible Navier-Stokes equation is satisfied everywhere in the computational domain. Second, the local discontinuities arising in the two-phase flow field have to be captured accurately. Third, the material interface betweenthe two fluids has to be represented accurately in each time step. In this work, a novel Hybridizable Discontinuous Galerkin (HDG) method is used for the spatial discretization. This hybrid method that belongs to the family of DG-FEM methods satisfies the divergence-free condition by introducing velocity and pressure trace variables of the same order plus a tailoredvelocity and pressure approximation inside the elements. Furthermore, the concepts of eXtended FEM (X-FEM) are used toapproximate discontinuities in the flow field by enriching the standard FEM approximation in elements where two fluids exist. Finally, the moving material interface between the twofluids is captured using the Level-Set method
44
Järrendal, Dan, and Dillekås Hans Tinggård. "Engreppsskördare med Head-Up Display." Thesis, Linköping University, Department of Management and Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8632.
Full textAbstract:
Arbetsbelastningen för föraren i en engreppsskördare är stor. Vid aptering måste föraren fokusera om blicken för att läsa av information från en Head-Down Display (HDD) samtidigt som föraren måste ha kontroll på kranspetsen vilket bidrar till arbetsbelastningen.
Syftet med projektet var att undersöka om arbetsbelastningen i engreppsskördare reducerades med Head-Up Display (HUD) under aptering. Först testades fyra HUD-gränssnitt i en simulator, därefter omarbetades gränssnitten innan de slutligen testades i en engreppsskördare i fält. En HUD-demonstrator utvecklades för detta ändamål.
Resultatet visade att arbetsbelastningen samt apteringstiderna minskade i simulatortestet med HUD jämfört med HDD. I fältstudien förblev arbetsbelastningen oförändrad men apteringstiderna minskade.
Att arbetsbelastningen minskade med HUD jämfört med HDD kan bero på att HUD är bättre än HDD och/eller att konceptens gränssnitt är effektivare att arbeta med än Valmet Maxi gränssnittet.
En HUD-demonstrator som fungerar under ljusstarka förhållanden och som tål påfrestningarna i en skördare borde utvecklas för vidare tester.
45
Wicht, Sebastian. "Atomar aufgelöste Strukturuntersuchungen für das Verständnis der magnetischen Eigenschaften von FePt-HAMR-Prototypmedien." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-216054.
Full textAbstract:
Dank der hohen uniaxialen Kristallanisotropie der L10-geordneten Phase gelten nanopartikuläre FePt+C-Schichten als aussichtsreiche Kandidaten zukünftiger Datenspeichersysteme. Aus diesem Grund werden in der vorliegenden Arbeit in Kooperation mit HGST- A Western Digital Company Prototypen solcher Medien strukturell bis hin zu atomarer Auflösung charakterisiert. Anhand von lokalen Messungen der Gitterparameter der FePt-Partikel wird gezeigt, dass die Partikel dünne, zementitartige Verbindungen an ihrer Oberfläche aufweisen. Zusätzlich werden große Partikel mit kleinem Oberfläche-Volumen-Verhältnis von kontinuierlichen Kohlenstoffschichten umschlossen, was die Deposition weiteren Materials verhindert. Eine Folge davon ist die Entstehung einer zweiten Lage statistisch orientierter Partikel, die sich negativ auf das magnetische Verhalten der FePt-Schicht auswirkt. Weiterhin wird die besondere Bedeutung des eingesetzten Substrats sowie seiner Gitterfehlpassung zur L10-geordneten Einheitszelle nachgewiesen. So lässt sich das Auftreten fehlorientierter ebenso wie das L12-geordneter Kristallite im Fall großer Fehlpassung und einkristalliner Substrate unterdrücken, was andererseits jedoch zu einer stärkeren Verkippung der [001]-Achsen der individuellen FePt-Partikel führt. Abschließend wird mithilfe der Elektronenholographie nachgewiesen, dass die Magnetisierungsrichtungen der FePt-Partikel aufgrund von Anisotropieschwankungen von den [001]-Achsen abweichen könnenHighly textured L10-ordered FePt+C-films are foreseen to become the next generation of magnetic data storage media. Therefore prototypes of such media (provided by HGST- A Western Digital Company) are structurally investigated down to the atomic level by HR-TEM and the observed results are correlated to the magnetic performance of the film. In a first study the occurrence of a strongly disturbed surface layer with a lattice spacing that corresponds to cementite is observed. Furthermore the individual particles are surrounded by a thin carbon layer that suppresses the deposition of further material and leads, therefore, to the formation of a second layer of particles. Without a contact to the seed layer these particles are randomly oriented and degrade the magnetic performance of the media. A further study reveals, that a selection of single-crystalline substrates with appropriate lattice mismatch to the L10-ordered unit cell can be applied to avoid the formation of in-plane oriented and L12-ordered crystals. Unfortunately, the required large mismatch results in a broadening of the texture of the [001]-axes of the individual grains. As electron holography studies reveal, the orientation of the magnetization of the individual grains can differ from the structural [001]-axis due to local fluctuations of the uniaxial anisotropy
46
Eklund, Rikard. "Presentation av taktisk information på bildskärm : Head-Up Display som stöd för tidsstyrd taxning med flygplan." Thesis, KTH, Ergonomi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-109317.
Full text
47
Gürkan, Ceren. "Extended hybridizable discontinuous Galerkin method." Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/664035.
Full textAbstract:
This thesis proposes a new numerical technique: the eXtended Hybridizable Discontinuous Galerkin (X-HDG) Method, to efficiently solve problems including moving boundaries and interfaces. It aims to outperform available methods and improve the results by inheriting favored properties of Discontinuous Galerkin (HDG) together with an explicit interface definition. X-HDG combines the Hybridizable HDG method with an eXtended Finite Element (X-FEM) philosophy, with a level set description of the interface, to form an hp convergent, high order unfitted numerical method. HDG outperforms other Discontinuous Galerkin (DG) methods for problems involving self-adjoint operators, due to its hybridization and superconvergence properties. The hybridization process drastically reduces the number of degrees of freedom in the discrete problem, similarly to static condensation in the context of high-order Continuous Galerkin (CG). On other hand, HDG is based on a mixed formulation that, differently to CG or other DG methods, is stable even when all variables (primal unknowns and derivatives) are approximated with polynomials of the same degree k. As a result, convergence of order k+1 in the L2 norm is proved not only for the primal unknown, but also for its derivatives. Therefore, a simple element-by-element postprocess of the derivatives leads to a superconvergent approximation of the primal variables, with convergence of order k+2 in the L2 norm. X-HDG inherits these favored properties of HDG in front of CG and DG methods; moreover, thanks to the level set description of interfaces, costly remeshing is avoided when dealing with moving interfaces. This work demonstrates that X-HDG keeps the optimal and superconvergence of HDG with no need of mesh fitting to the interface.
In Chapters 2 and 3, the X-HDG method is derived and implemented to solve the steady-state Laplace equation on a domain where the interface separates a single material from the void and where the interface separates two different materials. The accuracy and the convergence of X-HDG is tested over examples with manufactured solutions and it is shown that X-HDG outperforms the previous proposals by demonstrating high order optimum and super convergence, together with reduced system size thanks to its hybrid nature, without mesh fitting.
In Chapters 4 and 5, the X-HDG method is derived and implemented to solve Stokes interface problem for void and bimaterial interfaces. With X-HDG, high order convergence is demonstrated over unfitted meshes for incompressible flow problems.
X-HDG for moving interfaces is studied in Chapter 6. A transient Laplace problem is considered, where the time dependent term is discretized using the backward Euler method. A collapsing circle example together with two-phase Stefan problem are analyzed in numerical examples section. It is demonstrated that X-HDG offers high-order optimal convergence for time-dependent problems. Moreover, with Stefan problem, using a polynomial degree k, a more accurate approximation of interface position is demonstrated against X-FEM, thanks to k+1 convergent gradient approximation of X-HDG. Yet again, results obtained by previous proposals are improved.Esta tesis propone una nueva técnica numérica: eXtended Hybridizable Discontinuous Galerkin (X-HDG), para resolver eficazmente problemas incluyendo fronteras en movimiento e interfaces. Su objetivo es superar las limitaciones de los métodos disponibles y mejorar los resultados, heredando propiedades del método Hybridizable Discontinuous Galerkin method (HDG), junto con una definición de interfaz explícita. X-HDG combina el método HDG con la filosofía de eXtended Finite Element method (X-FEM), con una descripción level-set de la interfaz, para obtener un método numérico hp convergente de orden superior sin ajuste de la malla a la interfaz o frontera. HDG supera a otros métodos de DG para los problemas implícitos con operadores autoadjuntos, debido a sus propiedades de hibridación y superconvergencia. El proceso de hibridación reduce drásticamente el número de grados de libertad en el problema discreto, similar a la condensación estática en el contexto de Continuous Galerkin (CG) de alto orden. Por otro lado, HDG se basa en una formulación mixta que, a diferencia de CG u otros métodos DG, es estable incluso cuando todas las variables (incógnitas primitivas y derivadas) se aproximan con polinomios del mismo grado k. Como resultado, la convergencia de orden k + 1 en la norma L2 se demuestra no sólo para la incógnita primal sino también para sus derivadas. Por lo tanto, un simple post-proceso elemento-a-elemento de las derivadas conduce a una aproximación superconvergente de las variables primales, con convergencia de orden k+2 en la norma L2. X-HDG hereda estas propiedades. Por otro lado, gracias a la descripción level-set de la interfaz, se evita caro remallado tratando las interfaces móviles. Este trabajo demuestra que X-HDG mantiene la convergencia óptima y la superconvergencia de HDG sin la necesidad de ajustar la malla a la interfaz. En los capítulos 2 y 3, se deduce e implementa el método X-HDG para resolver la ecuación de Laplace estacionaria en un dominio donde la interfaz separa un solo material del vacío y donde la interfaz separa dos materiales diferentes. La precisión y convergencia de X-HDG se prueba con ejemplos de soluciones fabricadas y se demuestra que X-HDG supera las propuestas anteriores mostrando convergencia óptima y superconvergencia de alto orden, junto con una reducción del tamaño del sistema gracias a su naturaleza híbrida, pero sin ajuste de la malla. En los capítulos 4 y 5, el método X-HDG se desarrolla e implementa para resolver el problema de interfaz de Stokes para interfaces vacías y bimateriales. Con X-HDG, de nuevo se muestra una convergencia de alto orden en mallas no adaptadas, para problemas de flujo incompresible. X-HDG para interfaces móviles se discute en el Capítulo 6. Se considera un problema térmico transitorio, donde el término dependiente del tiempo es discretizado usando el método de backward Euler. Un ejemplo de una interfaz circulas que se reduce, junto con el problema de Stefan de dos fases, se discute en la sección de ejemplos numéricos. Se demuestra que X-HDG ofrece un alto grado de convergencia óptima para problemas dependientes del tiempo. Además, con el problema de Stefan, usando un grado polinomial k, se demuestra una aproximación más exacta de la posición de la interfaz contra X-FEM, gracias a la aproximación del gradiente convergente k + 1 de X-HDG. Una vez más, se mejoran los resultados obtenidos por las propuestas anteriores
48
Semati, Massimiliano. "Soluzioni per il controllo delle testine di lettura/scrittura in hard disk drive magnetici." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/11748/.
Full textAbstract:
Questa tesi descrive alcune tecniche realizzative e algoritmi di controllo per il posizionamento delle testine di lettura/scrittura in hard disk drive magnetici. Viene presentata l'attuazione a due stadi delle testine per incrementare la banda frequenziale del sistema, in cui un motore VCM funge da primo stadio e come secondo stadio si utilizza un microattuatore, di tipo piezoelettrico o elettromagnetico o elettrotermico. Il posizionamento della testina sulle tracce magnetiche dei dischi contenenti i dati si divide in due fasi: track-seeking e track-following, che presentano diversi requisiti di velocità e precisione, per questo motivo si descrive il metodo dello switching control. Successivamente viene formulato un modello matematico nello spazio degli stati degli stati dell'attuatori a due stadi e il relativo controllo in retroazione, basato su osservatore dello stato. Inoltre per il track-seeking si propone il controllo a due gradi di libertà e per il track-following il metodo del disaccoppiamento della sensitività. Infine si riportano due novità tecnologiche per gli hard disk magnetici: l'attuazione a tre stadi, che sfrutta un secondo microattuatore, di tipo termico, e gli hard disk riempiti d'elio ed ermeticamente sigillati, che semplificano il controllo grazie alla minore turbolenza del gas e al suo minor peso.
49
Zhu, Xi. "High frequency CMOS integrated filters for computer hard disk drive and wireless communication systems." Thesis, University of Hertfordshire, 2008. http://hdl.handle.net/2299/2069.
Full textAbstract:
Operational transconductance amplifier and capacitor (OTA-C) filters have outstood among different types of filter due to high frequency and low power capabilities in the main stream digital CMOS technology. They have been widely used in computer hard disk drive (HDD) and wireless communication transceivers. OTA-C filters based on cascade and passive ladder simulation are well-known. However, multiple loop feedback (MLF) OTA-C filters which have certain advantages still have the scope for further research. So far there have been no explicit formulas for current-mode leapfrog (LF) filter design and performance evaluation of current-mode MLF OTA-C filters are still lacking. From application viewpoints, read channels for computer hard disk drives require very high frequency continuous-time filters. This automatically disqualifies active- RC/MOSFET-C filters and OTA-C filters become the only solution. In wireless communications, active-RC/MOSFET-C filters have been proved useful for mobile systems whose baseband frequency falls below a few MHz. However, for wireless LANs with the frequency of several tens of MHz, OTA-C filters are a strong candidate. Whilst in HDD read channels, cascaded OTA-C architectures have been most utilized and in wireless receivers, OTA-C structures based on ladder simulation have been popular, MLF OTA-C filters have not been practically used in either of the applications. This thesis describes some novel designs and applications of multiple loop feedback OTA-C filters with extensive CMOS simulations. Analogue filters for computer hard disk drive systems are first reviewed; the state of the art and design considerations are provided. Three VHF linear phase lowpass OTA-C filters are then designed, which include a seventh-order and a fifth-order current-mode filter based on the follow-the-leader-feedback (FLF) structure and a seventh-order voltage-mode filter using the inverse FLF (IFLF) configuration. These filters all have very low power consumption. The synthesis and design of general current-mode LF OTA-C filters are conducted next. Iterative design formulas for both all-pole and finite-zero functions are derived and explicit formulas for up to sixth-orders are given. These formulas are very easy to use for designing any type of characteristics. Subsequently, linear phase lowpass OTA-C filter design for HDD read channels using LF structures are investigated in details. A current-mode filter and a voltage-mode filter using the fifth-order LF structure are presented. The two filters can operate up to 800MHz and have very small passband phase ripple. Analogue filters for wireless communication baseband applications are also reviewed thoroughly in this thesis, where the design of a fourth-order current-mode FLF Butterworth lowpass OTA-C filter for multi-standard receivers is presented. Then two fifth-order current-mode elliptic lowpass OTA-C filters based on respective LF and FLF structures for wireless communication baseband are designed. Fifth-order voltage-mode IFLF and LF elliptic lowpass filters are also presented. All these MLF baseband filters designed can operate up to 40MHz to cover all important wireless and mobile standards. Simulations show that the LF structures have better dynamic range and stopband attenuation performances than the FLF and IFLF configurations.
50
Chiou, Wei-Rong, and 邱威融. "Miniemulsion copolymerization kinetics of HDDA/MMA and HDDA/styrene based microgel particles." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/84527723935489011168.
Full textAbstract:
碩士國立臺灣科技大學
化學工程系
104
The isothermal kinetic of miniemulsion copolymerization of 1,6- hexanediol diacrylate (HDDA) /styrene(ST) and 1,6-hexanediol diacryl- ate (HDDA) /methyl methacrylate (MMA) system was investigate by using differential scanning calorimeter ( DSC ) in this work . Miniemuslion and solution ( solvent such as toluene) copolymerization were carried out.The model-fitting method was linked with the model- free method was used to decide the relevant kinetic parameters. The reaction mechanisms for miniemulsion copolymerization and solution copolymerization were satisfactorily predicted by the nucleation Avrami - Erofeyev model [g(α)=-[ln(1-α) ]^(1/n) ] . The minieulsoin copolymer- izations were characterized by TEM、 FTIR.