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Articoli di riviste sul tema "Dispositif non lineaire"
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Droal, C., e G. Tymen. "Determination des distributions dimensionnelles des aerosols a partir de deux algorithmes d'inversion non-lineaire appliques a plusieurs dispositifs d'echantillonnage". Journal of Aerosol Science 28, n. 2 (marzo 1997): 328. http://dx.doi.org/10.1016/s0021-8502(97)86825-5.
Testo completo
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Dean, Bayli, Tyler Wildes, Joseph Dean, David Shin, Connor Francis, Mathew Sebastian, Laura Falceto Font, Ginger Moore, Brandon Wummer e Catherine Flores. "EXTH-70. IMMUNOTHERAPY REVERSES GLIOMA-DRIVEN DYSFUNCTION OF IMMUNE SYSTEM HOMEOSTASIS". Neuro-Oncology 24, Supplement_7 (1 novembre 2022): vii225. http://dx.doi.org/10.1093/neuonc/noac209.868.
Testo completoAbstract (sommario):
Abstract BACKGROUND Glioma-induced immune disfunction has been described in a limited number of studies, and here we further demonstrate that gliomas also interrupt the cellular differentiation programming and outcomes of hematopoietic stem cells (HSC) in the bone marrow. HSCs from glioma-bearing mice are re-programmed and driven towards expansion of myeloid lineage precursors myeloid-derived suppressor cells (MDSC) in secondary lymphoid organs. However, we found this is reversed by immunotherapy. Adoptive cellular therapy (ACT) has been demonstrably efficacious in multiple preclinical models of CNS malignancies, and here we describe how glioma-induced disfunction is reversed by this immunotherapeutic platform. METHODS The impact of orthotopic KR158B glioma on HSCs was evaluated in an unbiased fashion using single cell RNAseq of lineage- cells and phenotypically using flow cytometry. Mature myeloid cell frequencies and function were also evaluated using flow cytometry. Finally, ACT containing total body irradiation, tumor-specific dendritic cells, tumor-reactive T cells, and HSCs isolated from glioma-bearing or non-tumor-bearing mice was used to evaluate cell fate differentiation and survival. RESULTS We observed differential gene expression of HSCs in tumor-bearing versus healthy mice coupled with an expansion of myeloid lineage subsets in glioma-bearing mice. Interestingly, MDSCs from glioma-bearing mice demonstrated hyper suppressive capacity as compared to MDSCs from non-tumor-bearing hosts. Interestingly, treatment with ACT overcame the suppressive properties of glioma-bearing HSCs. When HSCs from tumor-bearing mice were transferred with ACT, we observed significant survival benefit and long-term cures in orthotopic glioma models compared with mice treated with ACT using non-glioma-bearing HSPCs. CONCLUSIONS These findings demonstrate the suppressive disposition in HSCs from glioma-bearing hosts can be redirected using ACT for significant survival benefit. Collectively, these data demonstrate gliomas impact the hematopoietic compartment at the progenitor level to promote expansion of suppressive myeloid cells and their progenitors. However, ACT can overcome this bias and provide lasting anti-tumor effects.
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D’ascenzio, Anna. "Linee di cura. La mobilità biografica nello spazio del Terzo Settore". WELFARE E ERGONOMIA, n. 2 (gennaio 2023): 43–58. http://dx.doi.org/10.3280/we2022-002004.
Testo completoAbstract (sommario):
Nel paper si analizzerà il professionista della cura come un attore sociale che agisce all'interno del Terzo settore. L'attore occupa uno spazio di riproduzione sociale storicizzato da rapporti di forza, alleanze di status, conflitti di ruolo ed economie di scala, in un campo di trasformazioni sociali. In tale spazio, pratiche e retoriche sono da mettere in relazione alla più complessa questione antropolo-gica del dono. Nel testo si proverà a definire qualitativamente il grado di irriflessività/riflessività nella professione di cura (di per sé soggetto relazionale) come dialettica della vulnerabilità tra il richiedente cura e l'operatore sociale. Come già scritto da Pierre Bourdieu rispetto alla formazione dell'habitus, l'agente sociale risulta essere l'effetto di una complessa combinazione di capitali (economici, culturali e relazionali) in un campo economico. Nel nostro caso, egli è oggetto di habitus ma anche di un apriori giuridico definito come Politique de la Ville. La sintetica espressione indica, anche nel caso italiano, una forma di sovranità statuale, geograficamente localizzata, generata della riscrittura del Titolo V nella Costituzione italiana (2001) e dell'elaborazione della Legge 328/2000. Nel testo si proverà a spiegare che entrambi i dispositivi, oltre a con-tribuire alla fine dei Trente Glorieuses, partecipano al diverso funzionamento dello Stato sociale, ma anche alla diversa definizione professionale dell'operatore. Il soggetto/oggetto di tale traiettoria professionale agisce ed è agito dalla norma, all'interno di un processo non lineare e asimmetrico. Un pro-cesso che non gli assicura un posizionamento sociale solido. Metodologicamente, la figura dell'operatore sarà indagata come esito di una traiettoria biografica ordinata da uno status vulnerabile correlato a polisemici ruoli di dipendenza e creatività. .
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Borate, Uma, Amir T. Fathi, Bijal D. Shah, Daniel J. DeAngelo, Lewis B. Silverman, Todd Michael Cooper, Tina M. Albertson et al. "A First-In-Human Phase 1 Study Of The Antibody-Drug Conjugate SGN-CD19A In Relapsed Or Refractory B-Lineage Acute Leukemia and Highly Aggressive Lymphoma". Blood 122, n. 21 (15 novembre 2013): 1437. http://dx.doi.org/10.1182/blood.v122.21.1437.1437.
Testo completoAbstract (sommario):
Abstract Background CD19, a member of the immunoglobulin superfamily, is a B-cell specific marker that is found on B cells as early as the pro-B cell stage. CD19 is maintained upon malignant transformation and is expressed in the majority of patients with B-lineage leukemia and non-Hodgkin lymphoma (NHL). SGN-CD19A is a novel antibody-drug conjugate composed of a humanized anti-CD19 monoclonal antibody conjugated to the microtubule-disrupting agent monomethyl auristatin F (MMAF) via a maleimidocaproyl (mc) linker. Upon binding to CD19, SGN-CD19A internalizes and releases cys-mcMMAF, which binds to tubulin and induces G2/M arrest and apoptosis in the targeted cells. Methods A first-in-human, phase 1, open-label, dose-escalation study has been initiated to investigate the safety, tolerability, pharmacokinetics (PK), and antitumor activity of SGN-CD19A in adult and pediatric patients with relapsed or refractory (R/R) B-cell leukemia or highly aggressive B-cell lymphoma (CT.gov NCT01786096). Eligible patients must have a pathologically confirmed diagnosis of B-cell acute leukemia (B-ALL), Burkitt leukemia or lymphoma, or B-cell lymphoblastic lymphoma (B-LBL), and be R/R to at least 1 (adults) or 2 (pediatric) prior systemic regimens. A modified continual reassessment method is being used for dose allocation and maximum tolerated dose (MTD) estimation. SGN-CD19A is administered IV on Days 1 and 8 of 21-day cycles at up to 7 cohort-specific doses (0.3–2.3 mg/kg). Results Thirteen patients (11 adults, 2 pediatric) with R/R leukemia (9 B-ALL) or lymphoma (3 B-LBL, 1 Burkitt lymphoma) have been treated in this ongoing study. Adults (73% female) have a median age of 60 years (range, 26–74) and have received a median of 2 prior systemic therapies (range, 1–6). Four of the 11 adults (36%) have also received an allogeneic stem cell transplant (SCT). The pediatric patients, 2 females 13-and 14-years-old, have each received 3 prior systemic therapies; one of the pediatric patients has also received 2 allogeneic SCTs. To date, patients have been treated at 0.3 mg/kg (2 patients), 0.6 mg/kg (3 patients), 1.0 mg/kg (3 patients), and 1.3 mg/kg (5 patients). The maximum number of cycles received by a patient is 7. Four patients remain on treatment and 9 patients have discontinued treatment (7 due to progressive disease, 1 because of investigator decision, and 1 due to death). One patient with B-ALL treated at 1.0 mg/kg developed cardiac arrest in the setting of pre-existing electrolyte abnormalities and died 7 days after the first dose of SGN-CD19A; although this event was considered unrelated to study drug by the investigator, a possible relationship could not be excluded due to temporal association. Treatment-emergent adverse events reported for ≥10% of adult patients were nausea (64%); fatigue and pyrexia (55% each); chills (36%); headache (27%); and dyspnea, hypertension, oral pain, thrombocytopenia, tumor lysis syndrome, and vomiting (18% each). Drug-related AEs in adult patients were pyrexia (55%); nausea (45%); chills (36%); fatigue (27%); and headache, oral pain, and blurred vision (9% each). Drug-related AEs reported for the pediatric patients were abdominal pain, cough, diarrhea, dyspepsia, hyperuricemia, nausea, peripheral neuropathy, pruritus, pyrexia, tachycardia, and urticaria (all Grade 1 or 2, each in one patient). Preliminary data demonstrate rapid clearance of antibody-drug conjugate at low doses in patients with leukemia, suggesting target-mediated drug disposition. To date, best responses for patients with lymphoma are stable disease (2 patients) and progressive disease (2 patients). Best responses for the 8 leukemia patients with available response assessments are complete remission (1 adult at 1.3 mg/kg); resistant disease with clinical benefit, i.e., improvement in leukemia-related symptoms (4 patients); and progressive disease (3 patients). Conclusions MTDs have not yet been identified for adult or pediatric patients and dose-escalation continues in both populations. Antitumor activity has been observed, including 1 complete remission in a heavily pretreated B-ALL patient. Nonlinear clearance of the antibody-drug conjugate in leukemia patients suggests target-mediated disposition. Updated safety, PK, and response data will be presented at the meeting. A second trial is evaluating SGN-CD19A every 3 weeks in aggressive B-cell NHL (CT.gov NCT01786135). Disclosures: Borate: Seattle Genetics, Inc.: Research Funding; Genoptix: Consultancy. Fathi:Millennium: Research Funding; Seattle Genetics, Inc.: Advisory/Scientific board membership Other, Research Funding; Agios: Membership on an entity’s Board of Directors or advisory committees; Teva: Membership on an entity’s Board of Directors or advisory committees. Shah:Seattle Genetics, Inc.: Research Funding; NCCN: Membership on an entity’s Board of Directors or advisory committees; SWOG: Membership on an entity’s Board of Directors or advisory committees; Celgene: Speakers Bureau; Janssen/Pharmacyclics: Speakers Bureau. DeAngelo:Seattle Genetics, inc.: Research Funding. Silverman:Seattle Genetics, Inc.: Advisory/scientific board membership Other. Cooper:Seattle Genetics, Inc.: Research Funding. Albertson:Seattle Genetics, Inc.: Employment, Equity Ownership. O'Meara:Seattle Genetics, Inc.: Employment, Equity Ownership. Sandalic:Seattle Genetics, Inc.: Employment, Equity Ownership. Stevison:Seattle Genetics, Inc.: Employment, Equity Ownership. Chen:Seattle Genetics, Inc.: Consultancy, Research Funding, Speakers Bureau, Travel expenses Other.
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Fathi, Amir T., Robert Chen, Tanya M. Trippett, Maureen M. O'Brien, Daniel J. DeAngelo, Bijal D. Shah, Todd M. Cooper et al. "Interim Analysis of a Phase 1 Study of the Antibody-Drug Conjugate SGN-CD19A in Relapsed or Refractory B-Lineage Acute Leukemia and Highly Aggressive Lymphoma". Blood 124, n. 21 (6 dicembre 2014): 963. http://dx.doi.org/10.1182/blood.v124.21.963.963.
Testo completoAbstract (sommario):
Abstract Background CD19, a B cell-specific marker, is expressed in the majority of patients with B-lineage leukemia and non-Hodgkin lymphoma. SGN-CD19A is a novel antibody-drug conjugate (ADC) composed of a humanized anti-CD19 monoclonal antibody conjugated to the microtubule-disrupting agent monomethyl auristatin F (MMAF) via a maleimidocaproyl linker. Methods This first-in-human, phase 1, open-label, dose-escalation study is investigating the safety, tolerability, pharmacokinetics, and antitumor activity of SGN-CD19A in adult and pediatric patients with relapsed or refractory B-cell leukemia or highly aggressive lymphoma (NCT 01786096). Eligible patients must have B-cell acute lymphoblastic leukemia (B-ALL) or lymphoma (B-LBL), Burkitt leukemia or lymphoma, and be relapsed or refractory to at least 1 prior systemic regimen. A modified continual reassessment method is used for dose allocation and maximum tolerated dose (MTD) estimation for both pediatric and adult patients. The study is evaluating 2 schedules of IV SGN-CD19A administration: weekly (Days 1 and 8 of 21-day cycles; 0.3-4.5 mg/kg) or every 3weeks (q3week; 0.5-6 mg/kg). Results To date, 49 patients with relapsed or refractory leukemia (n=40) or lymphoma (n=9) have been treated. Median age of adult (n=38) and pediatric patients (n=11) was 37 and 11 years (range, 18-74 and 1-16), respectively. Patients received a median of 2 prior therapies (range 1-9); 14 patients (29%) previously received an allogeneic stem cell transplant. On the weekly schedule, 39 patients (28 adult, 11 pediatric) have been treated, and the median number of cycles is 2.5 (adults; range, 1-12) or 1 (pediatric; range, 1-4). On the q3week schedule, 10 adult patients have been treated, and the median number of cycles is 2.5 (range, 1-4) to date. Six patients remain on study treatment (3 on each schedule), and enrollment is ongoing. The toxicity profiles were similar across both dosing schedules (0.3-2.3 mg/kg weekly and 4-5 mg/kg q3week) and across adult and pediatric patients. The most frequently reported drug-related AEs included pyrexia, nausea, chills, vomiting, blurred vision, and dry eye. Frequent infusion-related reactions were observed early in the study, and recommendation for premedication was instituted. Ocular events were also observed and treated with ophthalmic steroids; steroid eye drop prophylaxis was instituted with each dose. Corneal findings consistent with superficial microcystic keratopathy were observed in 13 adult patients (34%) and in 1 pediatric patient (9%). Grade 3/4 corneal AEs have been observed in 4 adult patients; the majority of these events have resolved or improved to Grade 1 or 2. Steroid eye drop prophylaxis has reduced the incidence of Grade 3/4 events at this interim analysis. Three DLTs were observed: acidosis in a pediatric patient at 1 mg/kg weekly, cytokine release syndrome in an adult patient at 2 mg/kg weekly, and asymptomatic Grade 4 AST elevation in an adult patient at 5 mg/kg q3week. MTD has not yet been determined. SGN-CD19A ADC pharmacokinetic profiles indicate target-mediated drug disposition in patients with leukemia. Plasma ADC exposures generally increased with doses and were lower than those in patients with lymphoma. To date, no objective responses were observed in 9 efficacy-evaluable pediatric patients or in 3 adult patients with Burkitt lymphoma/leukemia. However, in efficacy-evaluable adult patients with B-ALL/B-LBL, objective responses were observed in 6 of 25 patients treated on the weekly schedule (3 CR, 2 CRp, 1 PR), and in 4 of 8 patients treated on the q3week schedule (2 CR, 2 CRp). Of 8 B-ALL patients with CR/CRp, 6 were MRD negative. Conclusions MTDs have not yet been identified, and dose escalation continues on weekly and q3week schedules. SGN-CD19A has been generally well tolerated. At this interim analysis, objective responses were observed in 30% (10 of 33) of heavily pretreated adult B-ALL/B-LBL patients dosed weekly or q3week. Evidence of activity in relapsed/refractory patients and lack of overlapping toxicities suggest opportunities for combination with conventional anti-leukemic therapies in lymphoblastic malignancies. Disclosures Fathi: Ariad: Consultancy; Exelixis: Research Funding; Takeda pharmaceuticals International Co.: Research Funding; Seattle Genetics, Inc.: Consultancy, Research Funding. Off Label Use: SGN-CD19A is an investigational agent being studied in patients with B-cell malignancies. SGN-CD19A is not approved for use. . Chen:Seattle Genetics, Inc.: Consultancy, Research Funding, Speakers Bureau, Travel expenses Other. Trippett:OSI Pharmaceuticals: Research Funding; Seattle Genetics, Inc.: Research Funding. O'Brien:Seattle Genetics, Inc.: Research Funding. DeAngelo:Seattle Genetics, Inc.: Research Funding. Shah:Pharmacyclics: Consultancy; SWOG: Consultancy; Celgene: Consultancy, Speakers Bureau; NCCN: Consultancy; Seattle Genetics, Inc.: Research Funding; Janssen: Consultancy. Cooper:Seattle Genetics, Inc.: Research Funding. Foran:Seattle Genetics, Inc.: Research Funding. Hale:Seattle Genetics, Inc.: Research Funding. Pressey:Seattle Genetics, Inc.: Research Funding. Silverman:Seattle Genetics, Inc.: Research Funding. Tibes:Seattle Genetics, Inc.: Research Funding. Kim:Bayer: Consultancy; Eli Lily: Consultancy; Seattle Genetics, Inc.: Consultancy, Research Funding. Albertson:Seattle Genetics, Inc.: Employment, Equity Ownership. Sandalic:Seattle Genetics, Inc.: Employment, Equity Ownership. Zhao:Seattle Genetics, Inc.: Employment, Equity Ownership. Borate:Genoptix: Consultancy; Seattle Genetics, Inc.: Research Funding.
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Gornik, Sebastian G., Victor Flores, Franziska Reinhardt, Lieselotte Erber, Dayana E. Salas-Leiva, Olga Douvropoulou, Imen Lassadi et al. "Mitochondrial genomes in Perkinsus decode conserved frameshifts in all genes". Molecular Biology and Evolution, 15 settembre 2022. http://dx.doi.org/10.1093/molbev/msac191.
Testo completoAbstract (sommario):
Abstract Mitochondrial genomes of apicomplexans, dinoflagellates and chrompodellids that collectively make up the Myzozoa, encode only three proteins (COB, COX1, COX3), contain fragmented rRNAs, and display extensive recombination, RNA trans-splicing, and RNA-editing. The early-diverging Perkinsozoa is the final major myzozoan lineage whose mitochondrial genomes remained poorly characterized. Previous reports of Perkinsus genes indicated independent acquisition of non-canonical features, namely the occurrence of multiple frameshifts. To determine both ancestral myzozoan and novel perkinsozoan mitochondrial genome features, we sequenced and assembled mitochondrial genomes of four Perkinsus species. These data show a simple ancestral genome with the common reduced coding capacity but disposition for rearrangement. We identified 75 frameshifts across the four species that occur as distinct types and that are highly conserved in gene location. A decoding mechanism apparently employs unused codons at the frameshift sites that advance translation either +1 or +2 frames to the next used codon. The locations of frameshifts are seemingly positioned to regulate protein folding of the nascent protein as it emerges from the ribosome. cox3 is distinct in containing only one frameshift and showing strong selection against residues that are otherwise frequently encoded at the frameshift positions in cox1 and cob. All genes lack cysteine codons implying a reduction to 19 amino acids in these genomes. Furthermore, mitochondrion-encoded rRNA fragment complements are incomplete in Perkinsus spp. but some are found in the nuclear DNA suggesting import into the organelle. Perkinsus demonstrates further remarkable trajectories of organelle genome evolution including pervasive integration of frameshift translation into genome expression.
Tesi sul tema "Dispositif non lineaire"
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PAYE, JEROME. "Fabry-perot non lineaire et effet stark optique : un dispositif de commutation optique ultra-rapide". Palaiseau, Ecole polytechnique, 1992. http://www.theses.fr/1992EPXX0008.
Testo completoAbstract (sommario):
Un codage de l'information sous la forme d'impulsions lumineuses ultra-breves permettrait d'atteindre des densites temporelles d'information tres grandes. C'est pourquoi la conception de dispositifs optiques ultra-rapides de commutation et de stockage de l'information devient necessaire. Le fabry-perot non lineaire est constitue d'un milieu optiquement non lineaire place entre deux miroirs paralleles. Ce systeme presente des comportements de commutation et de bistabilite optiques lorsqu'il est illumine avec des faisceaux d'intensites constantes. Le milieu non lineaire utilise est un semi-conducteur dans la zone de transparence, au voisinage du bord d'absorption. La non-linearite optique ultra-rapide est l'effet stark optique dont l'etude experimentale a forte intensite est presentee. L'analyse de la propagation dans ce milieu fortement dispersif et non lineaire est operee dans l'espace des phases temps-frequence a l'aide de la fonction de distribution de wigner. La propagation d'impulsions courtes dans un fabry-perot est examinee theoriquement, d'abord dans le cas lineaire pour mettre en evidence la notion de temps de reponse dependant de la frequence, puis dans le cas non lineaire ou apparaissent les effets de commutation. Une evaluation complete du role temporel et spectral de ce dispositif est donnee dans l'espace temps-frequence. Le comportement du fabry-perot non lineaire est etudie experimentalement par des mesures de transmission resolues en temps et par l'analyse des modifications de la forme temporelle des impulsions lors de la traversee du dispositif. La commutation aller-retour du fabry-perot a lieu en moins de deux picosecondes: le dispositif agit comme une perte optique a temps de commutation subpicoseconde
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Frey, Laurent. "Dispositif d'analyse dynamique de reseaux photoinduits. Application a divers materiaux photosensibles". Phd thesis, Université Paris Sud - Paris XI, 2000. http://pastel.archives-ouvertes.fr/pastel-00714027.
Testo completoAbstract (sommario):
Nous avons développé un véritable instrument de mesure et de caractérisation en temps réel des réseaux dynamiques photoinduits dans des matériaux holographiques. La technique des réseaux mobiles utilisée ne suppose pas connue la nature du reseau. Elle caracterise les modulations d'indice et d'absorption, a savoir leurs amplitudes et leurs dephasages par rapport au système de franges d'inscription. Il suffit de translater le reseau pendant un temps tres bref perpendiculairement aux franges, et de détecter les variations d'intensité des faisceaux qui les forment. Nous avons évalué les capacités et les limitations de ce dispositif qui fournit, pour la premiere fois, la cinetique de l'ensemble des paramétrés des reseaux. Nous l'avons adapte aux différents types de materiaux étudiés. Dans des matériaux photorefractifs organiques, le déphasage du réseau d'indice mesure indique bien un effet non local, dont les manifestations sont compatibles avec l'effet photorefractif qui serait cree par orientation des chromophores sur la direction du champ total. Nous avons aussi décelé un petit réseau d'absorption en quadrature avec le réseau d'indice majoritaire. Dans les sol-gels mous sik-dr1, nous avons sépare le réseau de surface du réseau de photoisomerisation, et mesure directement pour la premiere fois le déphasage de des réseaux de surface. Mettant un terme a un débat résultant d'expériences indirectes et controversées, cette valeur est en accord avec les modeles de photomigration. Nous avons montre que la variation temporelle quasi linéaire du déphasage des réseaux, observée avec des matériaux sol-gels et des cristaux liquides, est un artefact experimental qui affecte l'analyse de tous les matériaux lents : ce sont les franges d'inscription qui bougent par rapport au réseau photoinduit. Cette derive des franges est a l'origine des phénomènes de transfert d'énergie décrits dans certains de ces matériaux lents.
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Mandrillon, Vincent. "Réduction de la puissance de commande de microactionneurs au voisinage d'une instabilité magnétique ou élastique : application au bilame magnétostrictif". Université Joseph Fourier (Grenoble ; 1971-2015), 2000. http://www.theses.fr/2000GRE10212.
Testo completoAbstract (sommario):
Le bilame magnetostrictif est une structure elastique de base que l'on peut utiliser pour fabriquer des microactionneurs. Cette structure simple est constituee d'une membrane ou poutre en silicium recouverte d'une couche mince magnetostrictive. Nous etudions deux methodes permettant d'ameliorer ses performances. La premiere methode consiste a annuler la raideur magnetique du bilame en mettant a profit la possibilite de creer dans une couche a anisotropie uniaxiale une configuration d'aimantation instable en polarisant le materiau par un champ statique perpendiculaire a l'axe facile. Cette idee est etudiee et verifiee experimentalement dans les chapitre ii et iii. La deuxieme methode consiste a annuler la raideur elastique du systeme en utilisant le phenomene bien connu de flambement elastique des poutres. Nous developpons cette idee dans le chapitre iv. Dans le chapitre v nous menons a bien une etude analytique et experimentale du flambement elastique des poutres encastrees basee sur l'etude de trois dispositifs experimentaux.
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Manescu, Léonardo-Géo. "L'étude du régime non-sinusoïdal dans les systèmes électriques". Grenoble INPG, 1998. http://www.theses.fr/1998INPG0063.
Testo completoAbstract (sommario):
Dans le cadre de cette thèse on s'est intéressé à l'étude, par simulation, du fonctionnement des systèmes électriques en régime non-sinusoïdal, ainsi qu'aux effets de la pollution harmonique sur les éléments du système. Nous avons tout d'abord révisé les principaux paramètres du régime non-sinusoïdal (en proposant en complément les facteurs de distorsion intégratifs et dérivatifs) et la théorie de la puissance. Ensuite nous avons étudié la modélisation des principaux types de sources d'harmoniques, en adaptant des modèles existants ou en développant de nouveaux (pour les convertisseurs et les TCRs). Nous avons continué avec les éléments linéaires en choisissant parmi leurs modèles ceux appropriés à l'étude du régime non-sinusoïdal ou en proposant des modèles personnels, comme pour les transformateurs de puissance. On a toujours mis en évidence la caractéristique fréquentielle des paramètres des modèles. Après avoir évalué les principes potentiellement utilisables pour la modélisation du fonctionnement du système en régime non-sinusoïdal, nous avons choisi l'analyse harmonique itérative pour des études localisées, dont nous avons amélioré la convergence. Pour les études portant sur l'ensemble du système, nous avons développé un logiciel reposant sur la méthode dichotomique et la représentation hybride (temporelle et fréquentielle) des éléments non-linéaires. Les résultats des simulations réalisées dans le réseau IEEE 14 noeuds modifié, ont été utilisés dans l'analyse des interactions entre les sources harmoniques (principalement à l'aide de la puissance harmonique active totale). Dans la dernière partie, nous avons étudié les principaux types d'effets de la pollution harmonique et nous les avons détaillé pour différentes composantes du systèmeThis thesis deals with the study, by simulation, of power Systems in non-sinusoidal situations including harmonie pollution effects. First the principal parameters of non-sinusoidal wave shapes and working conditions and some éléments of power theory were reviewed. Novel complementary intégrais and derivatives harmonie distortion factors were proposed as well. Secondly, the modelling of the main types of harmonie sources was studied, either by adapting existing models where possible or by designing new models, such for power converters or TCRs. The linear parts of the System where then treated by the appropriated models or making new proposais (as for power transformers). After evaluating the simulation principles of the power Systems operating in non-sinusoidal conditions, itérative harmonie analysis was selected for localised studies, where its convergence properties were improved. For mil scale system studies, a software program was developed based on the dichotomous method, where the hybrid modelling, in both time and frequency domains, of non-linear éléments is assumed. The results of simulations conducted on the IEEE 14-bus modified test network were used in order to analyse the interactions between the harmonie sources, mainly by using the individual and total harmonie active powers. Finally, the principal types of harmonie pollution effects hâve been studied and detailed for several System constituents
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Boyer, Bertrand. "Comportement en micro-ondes de la charge capacité photo-induite sur un substrat de silicium". Grenoble INPG, 1998. http://www.theses.fr/1998INPG0069.
Testo completoAbstract (sommario):
La rencontre de l'optique et des microondes a donne naissance a un nouveau domaine : l'optomicroonde qui permet le traitement optique du signal microonde ou le controle optique de composants microondes. Cette these s'inscrit dans ce dernier axe. Lorsque l'on expose un semi-conducteur a une source optique dont les photons ont une energie suffisante, il y a creation dans le materiau de paires electron-trou modifiant la permittivite et la conductivite du substrat. Nous avons mis a profit ce principe pour realiser une charge adaptee accordable. L'extremite ouverte d'un stub depose sur une plaquette de silicium est illuminee par un signal optique et une tension continue ajoutee au signal microonde est appliquee dans le meme temps. Cette double commande optique et electrique nous permet de regler la frequence de rejection du stub sur une plage de plus de 60% en dessous de la frequence propre en dehors de toute illumination. Nous pouvons de plus ajuster le niveau de rejection entre 5 et 50 db. Apres des observations experimentales a deux longueurs d'onde optique differentes, nous nous sommes attaches a la modelisation de la charge photo-induite. Un modele intuitif a ete developpe sous la forme d'une resistance en serie avec une capacite. Il a ensuite ete verifie par des simulations electriques. Enfin, la resolution des equations de distribution des electrons et des trous a permis une approche plus fine du phenomene. Le role de chaque commande a ete mise en lumiere ce qui permet de mieux comprendre leur influence sur la repartition des charges dans le plasma photo-induit. Ainsi, nous avons mis en evidence l'influence de la diffusion laterale sur l'impedance de la charge photo-induite. D'autre part, les simulations ont montre l'importance de la duree de vie des porteurs et du dopage sur le modele. Finalement, la charge photo-induite sur un substrat de silicium a ete utilisee pour ses proprietes non-lineaires, dans le cadre du melange de deux signaux microondes. Les premieres simulations ont permis d'identifier les elements responsables de la generation des produits d'intermodulation. Ces travaux ouvrent de nombreuses perspectives d'utilisation de la charge photo-induite et de nouveaux horizons pour le controle optique de composants microondes.
6
NIEPCERON, ANDRE. "Dispositifs optiques a commutations ultrarapides utilisant des guides d'onde non lineaires". Paris 11, 1990. http://www.theses.fr/1990PA112236.
Testo completoAbstract (sommario):
Le dispositif etudie consiste en un guide d'onde optique en silicium epitaxie sur un substrat de saphir. Un reseau grave a la surface du silicium assure le couplage dans le guide d'une onde incidente dont la longueur d'onde correspond au seuil d'absorption du silicium, et qui peut donc faire apparaitre des non-linearites optiques importantes. La dynamique des phenomenes observes resulte de la competition entre la variation de l'indice de refraction du silicium associee a la photocreation de porteurs et celle due a l'echauffement du materiau lors de la recombinaison de ces porteurs. Apres un rappel sur les guides d'onde plans et sur l'excitation des modes d'un guide optique grace a un coupleur a reseau, nous examinons l'efficacite de couplage et l'amelioration des performances du dispositif en fonction des divers parametres: outre les parametres geometriques (pas et profondeur de modulation du reseau, epaisseur du film), la duree de vie des porteurs joue un role considerable dans la dynamique du dispositif en fonctionnement impulsionnel. Son amelioration permet d'observer deux commutations (dont une au moins sub-nanoseconde) sur les faisceaux de sortie au cours d'une impulsion incidente de 20 ns de duree. Le dispositif peut donc avoir un comportement bistable dynamique en accord avec les simulations numeriques. Les conditions d'excitation d'une onde dans le guide et leur influence sur l'evolution temporelle des intensites guidee, transmise et reflechie par le dispositif sont etudiees. En vue d'utiliser ces dispositifs en portes logiques, on a examine comment varient spatialement les diverses intensites de sortie sur l'etendue de la zone eclairee. Cette etude permet de determiner la zone ou le signal de sortie est le plus exploitable
7
Li, Hong Wu. "Autocommutation tout-optique : controle des instabilites spatiales dans deux dispositifs non-lineaires". Besançon, 1989. http://www.theses.fr/1989BESA2045.
Testo completoAbstract (sommario):
Le travail presente dans cette these porte principalement sur le controle des instabilites spatiales dans deux dispositifs optiques non-lineaires, excites en regime impulsionnel picoseconde. Dans la premiere partie, on fait un rappel de quelques notions de l'optique non-lineaire: l'effet kerr optique, autofocalisation, automodulation de phase, propagation de faisceaux soliton. La deuxieme partie de l'expose presente nos travaux sur une interface non-lineaire. Nous avons reussi a controler les instabilites spatiales dans la refraction non-lineaire sur cette interface. Nous avons etudie un interferometre de fabry-perot non-lineaire en regime transitoire, dans la troisieme partie: desaccord de phase par rapport a l'excitation, influence de l'incidence du faisceau d'entree sur les instabilites spatiales du dispositif
8
Bérard, Dominique. "Etude de dispositifs non lineaires de commutations optiques picosecondes en structure guide d'onde". Paris 11, 1991. http://www.theses.fr/1991PA112017.
Testo completoAbstract (sommario):
Cette these presente l'etude experimentale d'un dispositif permettant d'obtenir des commutations tout optique rapides base sur l'excitation d'une onde guidee dans un film non lineaire de silicium, epitaxie sur un substrat de saphir et recouvert d'argent, grace a un reseau de diffraction grave a la surface du film. Apres avoir rappele les proprietes du silicium sur saphir, nous revenons sur les guides d'onde optiques modules periodiquement et les conditions dans lesquelles un faisceau lumineux peut exciter efficacement une onde se propageant dans le guide. Nous montrons qu'il est possible d'utiliser les resonances angulaires correspondant a l'excitation d'ondes guidees pour obtenir des commutations optiques sur les intensites reflechie et guidee par les guides non lineaires. Les variations d'indice du silicium dues aux differents phenomenes induits sous excitation optique en bord de bande d'absorption sont evaluees. Nous detaillons le processus technologique developpe pour reliser les composants, reseau de diffraction de pas submicronique, les diffrents traitements etudies pour neutraliser les defauts induits dans le silicium lors de la gravure du reseau par usinage ionique. Des simulations numeriques en regime dynamique donnent des resultats en accord avec les mesures faites en regime non lineaire sous excitation par des impulsions optiques de duree 20 ns et 200 ps issues d'un laser nd/yag. Il est possible d'observer, sous excitation nanoseconde, une ou deux commutations subnanosecondes tres contrastees sur les faisceaux de sortie. L'instant d'apparition de ces commutations est precisement defini par les conditions d'excitation des dispositifs. Sous excitation picoseconde, des commutations d'environ 10 ps sont observees. Ces resultats permettent d'envisager une mise en forme de signaux optiques et sont interessants pour resoudre des problemes de synchronisation
9
SAUER, HERVE. "Etude theorique du fonctionnement dynamique de dispositifs a guide d'onde non lineaire pour la commutation optique". Paris 11, 1990. http://www.theses.fr/1990PA112023.
Testo completoAbstract (sommario):
Cette these presente l'etude theorique du fonctionnement dynamique de dispositifs pour la commutation optique dans le domaine des impulsions de quelques nanosecondes a quelques microsecondes. Ces dispositifs consistent en un guide d'onde non lineaire en silicium sur saphir avec un coupleur a reseau de diffraction. Apres quelques rappels theoriques sur l'optique non lineaire et sur la bistabilite optique via l'exemple du fabry-perot non lineaire, la structure detaillee des dispositifs est presentee. Une theorie simplifiee de leur fonctionnement quasistatique introduit les concepts de base pour la comprehension des phenomenes physiques se produisant dans la structure. Une methode matricielle de calcul de lapropagation des ondes electromagnetiques dans un milieu stratifie comportant une interface faiblement modulee est developpee afin de determiner les proprietes optiques des dispositions en regime lineaire. Puis les origines des non-linearites du silicium (principalament electronique et thermique) sont etablies, autorisant ainsi l'etude de leur dynamique et l'evaluqtion quantitative de leur importance. Pour mener a bien ce travail, une methode originale de calcul de la diffusion spatio-temporelle de la chaleur dans un milieu stratifie a ete mise au point. La synthese des etudes precedentes permet alors de disposer d'une modelisation approchee du fonctionnement dynamique global des dispositifs. Les simulations du fonctionnement des dispositifs, issues de la precedente modelisation, et par ailleurs en bon accord avec les observations experimentales, mettent en evidence le role fondamental de la competition entre les non-linearites d'origines thermique et electronique qui ont des effets antagonistes; elles permettent d'expliquer l'existence de commutations (sub-)nanosecondes sur les intensites lumineuses reflechie ou transmise par les dispositifs, et de comparer les comportements observes avec un fonct
10
Ducarne, Julien. "Modélisation et optimisation de dispositifs non-linéaires d’amortissement de structures par systèmes piézoélectriques commutés". Thesis, Paris, CNAM, 2009. http://www.theses.fr/2009CNAM0633/document.
Testo completoAbstract (sommario):
Afin de réduire les vibrations d'une structure, on utilise des éléments piézoélectriques connectés à des circuits électriques passifs. L'objectif est de se rapprocher de l'efficacité du contrôle actif sans en supporter la complexité et la consommation. On considère d'abord l'association d'une résistance (qui a un effet similaire à un amortissement visqueux) et éventuellement d'une inductance (permettant de réaliser un oscillateur accordé) aux éléments piézoélectriques. Ces systèmes ont des propriétés intéressantes, mais sont peu efficaces à moins d'un accord très précis de l'inductance. Afin d'obtenir des performances élevées sans accord précis, on étudie un circuit à commutation, qui se ferme et s'ouvre à des instants bien précis. L'effet de la charge, qui freine la structure, s'apparente à un frottement sec. En synchronisant les commutations sur les vibrations, le système est auto-adaptatif et peut être auto-alimenté. Les fortes non-linéarités entraînent une excitation haute fréquence de la structure qui peut rendre la synchronisation problématique. Deux modèles électromécaniques (analytique et éléments finis) réduits sont proposés, permettant de décrire la dynamique du système complet de manière précise et de mettre en valeur le couplage entre un mode de vibration et le circuit électrique. Ce couplage est déterminant pour la réduction de vibrations. Une étude de l'influence de divers paramètres permet d'optimiser les éléments piézoélectriques, les circuits, et les instants de commutation. Ces résultats sont vérifiés expérimentalement. On constate un bon accord avec la théorie ; la difficulté de synchroniser correctement la commutation est aussi constatéeIn order to reduce the vibrations of a mechanical structure, one can use piezoelectric elements connected to passive electrical circuits. The goal is to achieve the same efficiency as active vibration control without the associated complexity and energy consumption. First the use of a resistor (with an effect similar to viscous damping) and eventually of an inductor (allowing the creation of a tuned resonator) for the circuit is considered. These systems have interesting properties, but are not very efficient, except in the case of a finely tuned inductor. In order to obtain good performance without requiring a precise tuning, a switching circuit is considered. The switching process is synchronized on the vibrations, and the effect of the free electric charge (similar to a dry damping) reduces the vibrations. This system is self-adaptive and can be self-powered. However, the strong non-linearities create a high frequency excitation which may disturb the switch timing. Two different reduced electromechanical models (analytical and finite element) are proposed, allowing a description of the whole system dynamics with accuracy and to emphasize the coupling between one vibration mode and the circuit. This coupling is found to be decisive for the performance in vibration reduction. A study of the influence of various parameters allow the optimisation of the piezoelectric elements, electric circuits and switch timing. These results are experimentally tested and a good agreement with the predictions is obtained ; the difficulty of switch timing is also noticed
Capitoli di libri sul tema "Dispositif non lineaire"
1
Usman, Dashol Ishaya, e Mary Pam. "Effect of Disposition Effect on Investment Decision Making in Property Market in Plateau State, Nigeria". In Examining the Social and Economic Impacts of Conflict-Induced Migration, 83–98. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7615-0.ch005.
Testo completoAbstract (sommario):
The purpose of the chapter was to establish the effect of disposition on investment decision making in property market in Plateau State, Nigeria. Descriptive research design was used in the study. Primary data was collected using standard questionnaires with both closed and open-ended questions. The regression analysis results confirmed that there was a significant positive linear relationship between disposition and investor investment decision making in property market in Plateau State in Nigeria. The study concluded that disposition effects bias does not alter rationality in investment decision making. Disposition affected investment decisions. The main recommendation for investors is to make constant attempts to increase their awareness on behavioral finance by educating themselves on the field. Studying about the biases and reflecting on their decisions are likely to help achieve better self-understanding of the extent and manner to which they are influenced by emotions while making financial decisions under uncertainty.
2
ALEXANDER PATRICK CHAVES DE, SENA, ABREU JOSÉ LUCAS MOREIRA CAVALCANTI DE, SILVA ASAFE DOS SANTOS e SOUZA JOÃO MANOEL FREITAS. "SISTEMA EMBARCADO PARA O CONTROLE DE POSIÇÃO DE UM ROBÔ PARALELO TIPO DELTA LINEAR DE BAIXO CUSTO". In Perspectivas das Engenharias na Sociedade 5.0: Educação, Ciência, Tecnologia e Amor, 82–98. Instituto Internacional Despertando Vocações, 2020. http://dx.doi.org/10.31692/978-65-88970-06-5.82-98.
Testo completoAbstract (sommario):
O presente trabalho apresenta um sistema embarcado para o controle de posição de um robô paralelo com aplicação para acabamentos mecânicos. Anteriormente a máquina operava através do suporte computacional utilizando um dispositivo de alto custo. Dessa forma, com a substituição do aparato de processamento, sem a perda qualitativa, é possível estimar uma maior acessibilidade ao sistema concebido. Foi selecionada para a realização do trabalho a plataforma de software livre Arduino Due. O dispositivo controlado possui três bases manipuladas, com 300 mm de curso útil. Cada base é acionada por um motor de corrente contínua (CC) e um encoder, com resolução de 400 pulsos por volta. É utilizada a técnica de controle PID, com base no método Ziegler-Nichols de definição paramétrica. Para a melhor visualização, de forma gráfica, e definição dos dados empregados no sistema, desenvolveu-se um programa supervisório por meio da linguagem Java, que permite ao usuário definir os ganhos proporcionais, derivativos e integradores, bem como visualizar em tempo real a resposta sistemática perante aos parâmetros aplicados. Ao término do trabalho, pode se verificar um erro atuante máximo nos carros de aproximadamente 2,86%, obtendo por fim um dispositivo mais barato, com eficiência compatível com a original.
3
Gumbs, Michelle McAnuff. "Academic Capabilities, Social Positionality, and the Reading Performance of Historically Underserved Students in Online Small Groups". In Handbook of Research on Creating Motivational Online Environments for Students, 99–123. IGI Global, 2023. http://dx.doi.org/10.4018/978-1-6684-4533-4.ch006.
Testo completoAbstract (sommario):
The exploratory study uses a series of linear regression analyses to examine the unique and combined contributions of students' academic capabilities and disposition and social positionality to the reading performance of a national sample of 8th graders who participated in online small group learning during the COVID-19 lockdown. The average scaled score on the 2022 state assessment, collated in NAEP Data Explorer, was the dependent variable. Data on student-perceived academic capabilities and disposition, social positionality, and participation in online small groups came from that source. Analyses were done in Explorer. Results showed that positionality on race/ethnicity and disability robustly and negatively predicted reading performance for Black and Hispanic students. Gender mattered for these groups. For most students, the online small group format made no significant contribution to performance, although further analysis showed that the face-to-face format contributed significantly to higher performance for all students. Asian students were the only non-White groups for whom positive contributions were evident for online learning. However, the demographics for Asians were skewed by parental education. Risks, ramifications, and remedies for fractured relationships and classroom social dynamics are explored.
4
Alhaji Saganuwan, Saganuwan. "Ecotoxicity Effects of Lead Bullets in Human and Wildlife: The Consequences of Environmental Pollution, Low Intelligence Quotient, Brain Damage and Brain Overclaim Syndrome". In The Toxicity of Environmental Pollutants. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.105850.
Testo completoAbstract (sommario):
Bullets from gunshots made of lead are used to kill and arrest criminals, as they are also used by criminals to intimidate or kill innocents for psychosocial gains. So the increased environmental pollution caused by lead from industries, firearms, gasoline, among others is a source of concern for environmental health specialists, clinical toxicologists, experimental toxicologists, industrial toxicologists and ecotoxicologists. Lead can get into body system accidentally via oral, inhalational, epidermal, dermal, intraperitoneal, and intravenous routes. The toxicokinetic data of lead disposition via various routes of administrations are quite inconsistent. Hence the set blood limit concentration has been considered to be incorrect. In view of this, toxicokinetic data analysis of lead was carried out with intent to determine toxic doses of lead in various organs, and its toxicological consequences. Findings have shown that at lower doses, kinetics of lead is linear (first order), and at higher doses the kinetics becomes non-linear (zero-order). Metabolic processes modulated by lead could be either rate limiting or non–rate-limiting causing induction and inhibition of a myriad of metabolizing enzymes in liver, brain, kidney, intestine and lung. The LD50 of lead bullet in human was 450 mg/kg, which caused death in 9.1 days, and penicillamine (18 mg/kg) can be used for treatment. Mean residence time (MRT) and elimination half-life (T12β) were 25.8 and 18 days, respectively.
5
Homoki-Nagy, Mária. "Private Law Institutions in the Golden Bull". In Legal Heritage, 151–70. Ferenc Mádl Institute of Comparative Law, Central European Academic Publishing, 2023. http://dx.doi.org/10.47079/2023.eb.gbac.1_7.
Testo completoAbstract (sommario):
Among the provisions of the Golden Bull that concern public law, there is one that concerns private law, namely the law of succession. This so-called Article 4 mentions three questions. Firstly, it confirms the ancient custom that if the testator has descendants, they inherit the estate. If there are no descendants, the Golden Bull has given the testator the opportunity to dispose freely of his property. This is the measure to which the literature links the emergence of the right of testamentary disposition in the Hungarian legal system. The freedom of testamentary disposition is, however, limited by the institution of the daughter’s quarter, which must be given to the daughter’s heirs from the paternal ancestral property. Finally, the Golden Bull also establishes the ancient rules of legal inheritance by stating that if the testator had no descendants and no will, his ascendants or collateral relatives, ultimately the king, inherited the estate. The paper seeks to answer the question whether the possibility of making a will really only appeared in 1222. The documentary evidence of the 12th and 13th centuries provides evidence that wills were made with royal approval even before the Golden Bull. After 1222, the practice of requiring the king’s approval for a will to be valid continued, as attested by the royal seals on the documents. The other question is the scope of the legal inheritance in the century of the Golden Bull, which meant the lateral relatives of the clan. Initially, this did not extend beyond the grandparents’ parental lineage, but later, in order to preserve the ancestral property of the clan, the circle of collateral relatives who claimed the inheritance became wider and wider. This ambition was strengthened when the nobility asked the King’s approval to leave their property exclusively to their descendants. This eventually led to the issue of the decree of 1351, when Louis the Great renewed the Golden Bull, but deleted Article 4 of it, stating that the law of descent was to be the law of descent.
Atti di convegni sul tema "Dispositif non lineaire"
1
Kuntjoro, Wahyu, e Azlin Mohd Azmi. "Truss Disposition Optimization Using the Linear Extended Interior Penalty Function". In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-10355.
Testo completoAbstract (sommario):
This paper describes the development of truss optimization by finding its optimum topology (member disposition). The objective of this work is to obtain the truss with minimum weight that able to meet its design requirement (design constraints). Optimization is a mathematical technique used to find an optimum design, a design that minimize a certain objective function but still meet its design constraints. In this research, the objective function was the weight of the structure while the constraints were strength and displacement. Optimization was done by removing members which do not contribute to the load carrying capacity. Through conventional member size optimization non contributing members were identified and deleted. Linear Extended Interior Penalty Function was utilized to accomplish the mission. The truss structural responses were found by Finite Element Analysis coupled with an approximation procedure. Examples of a three-bar and six bar truss structures were demonstrated. Results showed that the truss topology could be optimized by members deletion strategy using the optimization procedure reported in this paper.
2
Parker, Stephen M., Matthew C. Walter e Daniel V. Sommerville. "Effects of Multiple Co-Linear Flaws on Crack Opening Area". In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63689.
Testo completoAbstract (sommario):
Cracking in boiling water reactor (BWR) core shroud welds has been identified in operating nuclear plants worldwide. The nuclear industry has taken extensive efforts to disposition and evaluate core shroud cracking, most notably within the BWR Vessel and Internals Project (BWRVIP) where many industry guidance documents have been published regarding core shroud integrity [1, 2, 3, 4]. This guidance is predominately focused on evaluating crack stability. Calculating through-wall leakage was not previously a focus of the existing BWRVIP inspection and evaluation (I&E) guidelines for the core shroud; however, there is some guidance in the current documentation. In recent years there has been some evidence of through-wall indications in the core shroud where the through-wall indications were aligned in an array of co-linear, short, flaws. There is currently no BWRVIP document or other open literature, to the authors’ knowledge, that provides insight into whether the crack opening displacements (CODs) for an array of co-linear, through-wall cracks are larger than that calculated for a single through-wall crack. Developing an understanding of the effect of co-linear cracks on the CODs and subsequent crack opening areas (COAs) of each crack is important in augmenting the existing guidance on how to appropriately disposition through-wall cracking in reactor internal components. Specifically, it is important to know if multiple co-linear cracks can lead to individual COAs that are larger than for a single crack of the same length, in order to perform accurate leakage rate calculations. The purpose of the study documented in this paper is to characterize the COA for axial co-linear crack distributions compared to the COA of an individual crack. Cracks that are aligned in series with an uncracked ligament between them are considered to be co-linear. To better understand how these crack distributions behave, an evaluation is conducted to analyze axial co-linear flaw configurations in core shrouds using traditional linear-elastic fracture mechanics (LEFM) and finite element analysis (FEA) techniques. Through FEA, the COAs and displacements of various co-linear flaw configurations are calculated and compared to the COAs for single flaw configurations. These flaw geometries are useful for the purpose of determining the potential core leakage associated with through-wall co-linear cracks. Co-linear crack configurations for a range of crack sizes and geometries are parametrically evaluated based on the ligament length between the co-linear cracks. Results show that crack openings of co-linear flaw configurations compared to a single flaw can vary substantially depending the crack size and ligament length. Trends of these crack openings are summarized within this report. While the object of this work is to provide criteria for the evaluation of reactor internals, the results can be applied to evaluate COD and COA in any component for which the cracking configuration and inherent assumptions of LEFM are applicable.
3
Merlo, Manuele, Fabio Negretto e Franco Maria Montevecchi. "The Effect of the Electrostatic Field on the Deflection of Microcantilever Biosensors". In ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95155.
Testo completoAbstract (sommario):
Microcantilever biosensors offer the capability to detect specific molecular binding like complementary DNA fragment hybridization or specific antibody-antigen binding. The cantilever deflection, which can be optically detected, is caused by the adsorption of biological molecules like DNA fragments upon the microcantilever surface and the subsequent specific binding to the complementary species. The cantilever deflection is due to the surface stress induced by the free energy variation on the cantilever surface. Contributions to the free energy variation come from a number of interactions within the molecules, such as electrostatic interactions, biomolecule conformational entropy and internal energy variation, hydration forces. In the present work the effect of the electrostatic field within DNA biomolecules on the cantilever deflection is investigated. The electrostatic field within double strand DNA molecules is studied by means of a Finite Element (FE) analysis aimed at numerically solving the non linear Poisson Boltzmann equation (PBE) in the domain representing the biomolecule system. The electrostatic analysis has been coupled to a FE structural analysis in order to evaluate the influence of the electrostatic field on the cantilever deflection. The double strand DNA molecules are modelled as a periodic disposition of cylinders negatively charged at the surface. The hexagonal and square DNA molecule patterns were compared, and the Manning condensation hypothesis was discussed. The results are shown for different operating conditions and compared with experimental data from literature.
4
Crosa, Giampaolo, Maurizio Lubiano e Angela Trucco. "Modelling of PV-Powered Water Electrolysers". In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90906.
Testo completoAbstract (sommario):
In the near future the hydrogen production by means of advanced water electrolysers powered by renewable hybrid energy systems (Photovoltaic solar/wind) could help to resolve the electricity supply and environmental problems relating to the use of fossil fuels. In the light of this perspective the hydrogen represents an alternative energy carrier, helping to overcome all the problems related to the intermittent nature of solar and wind sources. A non linear dynamic simulator of a photovoltaic-hydrogen energy system has been realised, aiming to provide a useful instrument for the development of innovative strategies for plant control and plant operating guidance. The lumped parameter physical approach has been used, applying the fundamental conservation laws of mass, energy and momentum to every component of the plant. The water electrolyser model has been tailored on the characteristics of an advanced pressurised system, using a Casale Chemicals S.A. advanced cell bipolar design, with alkaline electrolyte (KOH solution), whose mathematical models was described by the authors in previous papers. A first version of this simulator has been improved by introducing a reliable thermal model, able to predict the solar panel temperature profile that affects the PV array performance; the panel model has been modified in order to reproduce precisely the I/V characteristics of any PV module, starting from its nominal data. Thanks to this model improvement, the simulator allowed to be used to maximise the PV power production, evaluating different control strategies: a Maximum Power Point Tracking (M.P.P.T) block has been then introduced in the model to optimise the generated power by the photovoltaic plant. The Joule losses due to the PV field internal wiring and to its feeding connection with the electrolyser have been also considered: it consents to separately compute the energy losses in the different PV-electrolyser coupling configurations, thus evaluating the best panel disposition in order to minimise the electric power dissipation. The simulator proved to be able to robustly predict the performance of the PV-electrolysis system for different configurations, operating conditions and control strategies. A steady-state analysis not appears in fact to be an adequate tool for these purposes.
5
Walter, Matthew, e Daniel Sommerville. "Effects of Multiple Parallel Flaws on Crack Opening Area". In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63616.
Testo completoAbstract (sommario):
Cracking in boiling water reactor (BWR) core shroud welds has been identified in operating nuclear plants worldwide. The Boiling Water Reactor Vessel and Internals Project (BWRVIP) has published several reports providing inspection and evaluation (I&E) guidance for intergranular stress corrosion cracking (IGSCC) in the core shroud of BWRs. This guidance is predominately focused on evaluating crack stability. Calculating through-wall leakage was not previously a focus of the existing BWRVIP I&E guidelines for the core shroud; however, there is some guidance in the current documentation. In recent years there has been some evidence of through-wall indications in the core shroud where the through-wall indications were aligned in an array of parallel, short, flaws. BWRVIP-158-A contains rules for treating parallel flaws with respect to calculation of structural margin for both net section collapse (limit load) and brittle fracture (linear elastic fracture mechanics (LEFM)) failure modes. There is currently no BWRVIP document or other open literature, to the authors’ knowledge, that provides insight into whether the crack opening displacements (CODs) for an array of parallel through-wall cracks are larger than that calculated for a single through-wall crack. Developing an understanding of the effect of parallel cracks on the CODs and subsequent crack opening areas (COAs) of each crack is important in augmenting the existing guidance on how to appropriately disposition through-wall cracking in reactor internal components. Specifically, it is important to know if multiple parallel cracks can lead to individual COAs that are larger than for a single crack of the same length, in order to perform accurate leakage rate calculations. This paper documents linear-elastic finite element analyses (FEA) performed to study the effect of a parallel crack configuration on the resulting COA for the set of cracks compared to the COA calculated if each crack was treated as an individual crack, without adjacent cracking present. Various separation distances, number of crack cases and crack lengths are considered. While the object of this work is to provide criteria for the evaluation of reactor internals, the results can be applied to evaluate COD and COA in any component for which the cracking configuration and inherent assumptions of LEFM are applicable.