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Regulatory Mechanisms of the Immune System Downstream of Host and Microbial GlycansZhou, Julie Y. 25 January 2022 (has links)
No description available.
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Are We Going In There? The Role of Brief Narratives (TV ADs and PSAs) in Narrative Transportation and Second-Order Cultivation EffectsQuillin, Michael J. January 2014 (has links)
No description available.
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Детекција биоактивних супстанци одабраних врста гљива рода Ganoderma (Basidiomycota) и њихова биолошка активност / Detekcija bioaktivnih supstanci odabranih vrsta gljiva roda Ganoderma (Basidiomycota) i njihova biološka aktivnost / Detection of bioactive substances selected fungal species of the genus Ganoderma (Basidiomycota) and their biological activityRašeta Milena 23 September 2016 (has links)
<p> У оквиру ове докторске дисертације испитан је хемијски састав и биолошке активности ЕtOH, H<sub>2</sub>Oи CHCl<sub>3 </sub> екстраката четири врсте гљива рода<em> Ganoderma</em> (Basidiomycota): <em> G. applanatum, G. lucidum,G. pfeifferi, G. resinaceum</em> са територије Војводине.Хемијски састав анализираних врста је одређен<br />применом: ААЅ методе (састав макро- имикроелемената у сувим остацима гљива) и LC-MS/MS технике (квантитативни састав фенолних једињења и флавоноида) при чему је детектовано 12 једињења. Спектрофотометријским методама је одређен садржај протеина, шећера, укупних фенола и флавоноида, код којих је највећи садржај протеина утврђен за ЕtOH екстракте <em> G. applanatum </em>и <em>G. pfeifferi</em>. Испитивања биолошких активности екстраката обухватила су: одређивање<span id="cke_bm_779S" style="display: none;"> </span><em> in vitro</em><span id="cke_bm_779E" style="display: none;"> </span> и <em> in vivo</em> антиоксидантне, антимикробне, антиинфламаторне, антипролиферативне и антијабето<span id="cke_bm_780E" style="display: none;"> </span>гене aктивности. </p><p>Антиоксидантна активност (способност неутрализације слободних радикала и редукциони потенцијал) је одређена спектрофотометријским методама, при којој су најбољу активност остварили Н<sub>2</sub>О екстракти <em> G</em>. <em>applanatum.</em> Антимикробнa активност анализираних екстраката одређена је испитивањем антибактеријског, антифунгалног и антивиралног потенцијала где се издвојила<em> G. pfeifferi</em> врста. Антиинфламаторни потенцијал EtOH и CHCl<sub>3 </sub>екстраката одређен је<em> ex vivo </em> методом мерењем способности инхибиције продукције медијатора инфламације (продукти метаболизма арахидонске киселине) при којој су бољу активност испољили CHCl<sub>3</sub> екстракти.</p><p>Ефекат EtOH и H<sub>2</sub>O екстраката врста рода Ganoderma на раст MCF ћелијске линије испитан је MTT тестом, а посебно су се издвојили EtOH екстракти врста после 72h.</p><p>Остварена антидијабетогена активност EtOH и Н<sub>2</sub>О екстраката врста <span id="cke_bm_795S" style="display: none;"> </span><em>G. pfeifferi </em><span id="cke_bm_795E" style="display: none;"> </span>и <em> G. resinaceum</em> код алоксан-индукованог <em> D. mell<span id="cke_bm_796E" style="display: none;"> </span>itus-a </em> на експерименталним животињама праћена je регенерацијом ß- ћелија Лангерхансових острваца панкреаса. Као потенцијални нефро- и хепатопротективни агенси се издвајају екстракти<em> G. resinaceum.</em></p><p>Сумарно, укупни биопотенцијал анализираних врста рода Ganoderma на основу спроведених анализа хемијске kарактеризације и биолошке активности упућује на могућност њихове потенцијалне примене као нутрацеутика и додатака исхрани, у будућности уз неопходност додатних микохемијских истраживања ових врста, посебно терпеноида и полисахарида, као и других биолошких активности као што је неуропротективна.</p> / <p> U okviru ove doktorske disertacije ispitan je hemijski sastav i biološke aktivnosti EtOH, H<sub>2</sub>Oi CHCl<sub>3 </sub> ekstrakata četiri vrste gljiva roda<em> Ganoderma</em> (Basidiomycota): <em> G. applanatum, G. lucidum,G. pfeifferi, G. resinaceum</em> sa teritorije Vojvodine.Hemijski sastav analiziranih vrsta je određen<br />primenom: AAЅ metode (sastav makro- imikroelemenata u suvim ostacima gljiva) i LC-MS/MS tehnike (kvantitativni sastav fenolnih jedinjenja i flavonoida) pri čemu je detektovano 12 jedinjenja. Spektrofotometrijskim metodama je određen sadržaj proteina, šećera, ukupnih fenola i flavonoida, kod kojih je najveći sadržaj proteina utvrđen za EtOH ekstrakte <em> G. applanatum </em>i <em>G. pfeifferi</em>. Ispitivanja bioloških aktivnosti ekstrakata obuhvatila su: određivanje<span id="cke_bm_779S" style="display: none;"> </span><em> in vitro</em><span id="cke_bm_779E" style="display: none;"> </span> i <em> in vivo</em> antioksidantne, antimikrobne, antiinflamatorne, antiproliferativne i antijabeto<span id="cke_bm_780E" style="display: none;"> </span>gene aktivnosti. </p><p>Antioksidantna aktivnost (sposobnost neutralizacije slobodnih radikala i redukcioni potencijal) je određena spektrofotometrijskim metodama, pri kojoj su najbolju aktivnost ostvarili N<sub>2</sub>O ekstrakti <em> G</em>. <em>applanatum.</em> Antimikrobna aktivnost analiziranih ekstrakata određena je ispitivanjem antibakterijskog, antifungalnog i antiviralnog potencijala gde se izdvojila<em> G. pfeifferi</em> vrsta. Antiinflamatorni potencijal EtOH i CHCl<sub>3 </sub>ekstrakata određen je<em> ex vivo </em> metodom merenjem sposobnosti inhibicije produkcije medijatora inflamacije (produkti metabolizma arahidonske kiseline) pri kojoj su bolju aktivnost ispoljili CHCl<sub>3</sub> ekstrakti.</p><p>Efekat EtOH i H<sub>2</sub>O ekstrakata vrsta roda Ganoderma na rast MCF ćelijske linije ispitan je MTT testom, a posebno su se izdvojili EtOH ekstrakti vrsta posle 72h.</p><p>Ostvarena antidijabetogena aktivnost EtOH i N<sub>2</sub>O ekstrakata vrsta <span id="cke_bm_795S" style="display: none;"> </span><em>G. pfeifferi </em><span id="cke_bm_795E" style="display: none;"> </span>i <em> G. resinaceum</em> kod aloksan-indukovanog <em> D. mell<span id="cke_bm_796E" style="display: none;"> </span>itus-a </em> na eksperimentalnim životinjama praćena je regeneracijom ß- ćelija Langerhansovih ostrvaca pankreasa. Kao potencijalni nefro- i hepatoprotektivni agensi se izdvajaju ekstrakti<em> G. resinaceum.</em></p><p>Sumarno, ukupni biopotencijal analiziranih vrsta roda Ganoderma na osnovu sprovedenih analiza hemijske karakterizacije i biološke aktivnosti upućuje na mogućnost njihove potencijalne primene kao nutraceutika i dodataka ishrani, u budućnosti uz neophodnost dodatnih mikohemijskih istraživanja ovih vrsta, posebno terpenoida i polisaharida, kao i drugih bioloških aktivnosti kao što je neuroprotektivna.</p> / <p>Whitin this doctoral thesis the chemical composition and biological activity of EtOH, H<span id="cke_bm_699S" style="display: none;"> </span><sub>2</sub><span id="cke_bm_699E" style="display: none;"> </span>O and CHCl<sub>3 </sub>extracts of four fungal species which belong to genus<em> Ganoderma </em> (phylum Basidiomycota)<span id="cke_bm_700E" style="display: none;"> </span>: <em> G. applanatum, G. lucidum, G. pfeifferi, G. resinaceum</em> were determinated. The samples were collected from different localities in Vojvodina. Chemical characterization included: AAS methods (compositon of macro- and microelements in d.w. of fungi) and LC-MS/MS technique (quantitative analysis of phenolic compounds and flavonoids) wherein the 12 selected phenolic compounds were detected. The total proteins, sugars, phenolics and flavonoids content were determined using spectrophotometric methods. The highest protein content was determined in EtOH extracts of<span id="cke_bm_707S" style="display: none;"> </span><em> G. applanatum </em><span id="cke_bm_707E" style="display: none;"> </span>and <em>G. pfeifferi</em> species. In order to assess the biological potential, the in vitro and in vivo antioxidant, antimicrobial, anti-inflammatory, antiproliferative and antidiabetic activities of the extracts were investigated.<span id="cke_bm_708E" style="display: none;"> </span><br /> The antioxidant activity (the ability of neutralizing free radicals and reduction potential) estimated byspectrophotometric methods. The highest antioxidant potential was noticed in H<sub>2</sub>O extracts of <em>G. applanatum.</em> Evaluation of antimicrobial activity included the estimation of antibacterial, antifungal and antiviral activity, whereby the species <em> G. pfeifferi </em> showed the highest potential The anti-inflammatory activity of EtOH and CHCl<sub>3</sub> extracts was determined by ex vivo method measuring the ability of production inhibition of inflammation mediators (products of arachidonic acid metabolism), where the CHCl<sub>3</sub> extracts were exhibited better activity.<br /> The effect of EtOH and H<sub>2</sub>O extracts of<em> Ganoderma</em> species on the growth of the cell line MCF-7, has been examined using MTT assay (stand out ethanolic extracts of analyzed species after 72h incubation period).<br /> Achieved antidiabetic activity of EtOH and H<sub>2</sub>O extracts o<em>f<span id="cke_bm_725S" style="display: none;"> </span> G. pfeifferi<span id="cke_bm_725E" style="display: none;"> </span> </em>an<em>d G. resinaceum</em> at alloxan-i<span id="cke_bm_726E" style="display: none;"> </span>nduced D. mellitus in experimental animals was followed by regeneration of cells of Langerhans pancreatic islets. Extracts of <em> G. resinaceum </em> were allocated as a potential nephro- and hepatoprotective agents.<br />In summary, the overall biological potential of the analyzed species of the genus <em>Ganoderma</em> based on results for chemical and biological characterization indicate that they could be used as a nutraceuticals and food supplements in the future, with further the necessity of additional mycochemical investigation (especially terpenoids and polysaccharides) and other biological activity such as neuroprotective.</p>
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Application of the Stimulus-Driven Theory of Probabilistic Dynamics to the hydrogen issue in level-2 PSA. Application de la Stimulus Driven Theory of Probabilistic Dynamics (SDTPD) au risque hydrogène dans les EPS de niveau 2.Peeters, Agnès 05 October 2007 (has links)
Les Etudes Probabilistes de Sûreté (EPS) de niveau 2 en centrale nucléaire visent à identifier les séquences d’événements pouvant correspondre à la propagation d’un accident d’un endommagement du cœur jusqu’à une perte potentielle de l’intégrité de l’enceinte, et à estimer la fréquence d’apparition des différents scénarios possibles.
Ces accidents sévères dépendent non seulement de défaillances matérielles ou d’erreurs humaines, mais également de l’occurrence de phénomènes physiques, tels que des explosions vapeur ou hydrogène. La prise en compte de tels phénomènes dans le cadre booléen des arbres d’événements s’avère difficile, et les méthodologies dynamiques de réalisation des EPS sont censées fournir une manière plus cohérente d’intégrer l’évolution du processus physique dans les changements de configuration discrète de la centrale au long d’un transitoire accidentel.
Cette thèse décrit l’application d’une des plus récentes approches dynamiques des EPS – la Théorie de la Dynamique Probabiliste basée sur les Stimuli (SDTPD) – à différents modèles de déflagration d'hydrogène ainsi que les développements qui ont permis cette applications et les diverses améliorations et techniques qui ont été mises en oeuvre.
Level-2 Probabilistic Safety Analyses (PSA) of nuclear power plants aims to identify the possible sequences of events corresponding to an accident propagation from a core damage to a potential loss of integrity of the containment, and to assess the frequency of occurrence of the different scenarios.
These so-called severe accidents depend not only on hardware failures and human errors, but also on the occurrence of physical phenomena such as e.g. steam or hydrogen explosions. Handling these phenomena in the classical Boolean framework of event trees is not convenient, and dynamic methodologies to perform PSA studies are expected to provide a more consistent way of integrating the physical process evolution with the discrete changes of plant configuration along an accidental transient.
This PhD Thesis presents the application of one of the most recently proposed dynamic PSA methodologies, i.e. the Stimulus-Driven Theory of Probabilistic Dynamics (SDTPD), to several models of hydrogen explosion in the containment of a plant, as well as the developed methods and improvements.
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Přístupy k zajištění jaderné bezpečnosti u reaktorů 3. generace / Approach to the nuclaer safety of the 3rd generation nuclear reactorsPavlíček, Michal January 2010 (has links)
The main target of the master´s thesis is reviewing the generation III nuclear reactors in term of the nuclear safety. At first we have to learn some theory of the nuclear safety in order to understand safety systems of the generation III nuclear reactors. Therefore the thesis is divided into two parts. Legislative and technical approaches to nuclear safety are mentioned in the first part. Regulatory bodies, whose task is to supervise nuclear safety in the nuclear power plants, belongs to the legislative approaches. There are defined terms such as defence in depth, redundancy, diversity, etc. There are mentioned methods to assessing nuclear safety – deterministic and probabilistic methods, especially probabilistic methods, for which a simple example is provided. There are also mentioned active and passive safety systems and their significance for nuclear safety and inherent safety too. There is an example of the function of the active and passive safety systems of the EDU nuclear power plant in conclusion of this issue. The second part deals with description of the selected nuclear reactors in context of the construction of the new units of nuclear power plant in Temelín. The nuclear reactors from companies, which applied for the public tender opened by ČEZ, a. s., for the construction of the ETE 3+4. Thus, the nuclear reactor MIR-1200 by ATOMSTROYEXPORT (Russian Federation), the nuclear reactor AP1000 by WESTINGHOUSE (USA) and the nuclear reactor EPR by AREVA (France) are taken into account . Comparison of the generation II and these generation III+ nuclear reactors necessarily belongs to this master´s thesis. These the generation III+ nuclear reactors are compared with the nuclear reactor VVER 440 (EDU) and in particular with the nuclear reactor VVER 1000, which is operated in the nuclear power plant Temelín. The final chapter contains generally appraisal of the whole problem.
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Localisation of kallikreins in the prostate and association with prostate cancer progressionBui, Loan Thuy January 2006 (has links)
At present, prostate cancer is a significant public health issue throughout the world and is the second leading cause of cancer deaths in older men. The prostate specific antigen or PSA (which is encoded by the kallikrein 3/KLK3 gene) test is the current most valuable tool for the diagnosis and management of prostate cancer. However, it is insufficiently sensitive and specific for early diagnosis, for staging of prostate cancer or for discriminating between benign prostatic hyperplasia (BPH) and prostate cancer. Recent research has revealed another potential tumour marker, glandular kallikrein 2 (KLK2 gene/hK2 protein), which may be used alone or in conjunction with PSA to overcome some of the limitations of the PSA test. Twelve new kallikrein gene family members have been recently identified and, like hK2 and PSA, many of these genes have been suggested to be involved in carcinogenesis. In this study, the cellular localisation and level of expression of several of these newer kallikreins (KLK4, KLK5, KLK7, KLK8 and KLK11) was examined in prostate tissue, to provide an understanding of the association of their expression with prostatic diseases and their potential as additional biomarkers. Like PSA and hK2, the present observation indicated that each of these proteins, hK4, hK5, hK7, hK8 and hK11, was detected within the cytoplasm of the secretory cells of the prostate glands. For the first time, all of these newly-identified proteins were shown to be expressed in prostatic intraepithelial neoplasia (PIN) lesions, in comparison to normal glands and cancer lesions. In addition to cytoplasmic secretory cell expression, the localisation of hK4 to the basal cells and nuclei in prostatic lesions was intriguing. The intensity of hK4 staining in prostate tissue was strongest in comparison to the other newly-identified kallikrein proteins (hK5, hK7, hK8 and hK11). Therefore, KLK4/hK4 expression was characterised further to define this cellular localisation and examined in non-prostatic tissue and also in a larger number of prostate tissues in an attempt to determine its potential value as a biomarker for prostate disease. Three hK4 antipeptide polyclonal antibodies, derived against N-terminal, mid-region and C-terminal hK4 amino acid sequences, were used. The hK4 N-terminal antipeptide antibody was used to demonstrate the cellular localisation of hK4 in kidney, salivary glands, liver, testis, colon carcinoma, heart, endometrium and ovarian cancer, for the first time. The presence of hK4 in these non-prostate tissues was consistent with the previous reports using RT-PCR. The dual cytoplasmic and nuclear localisation of hK4 observed in the prostate above was also seen in these tissues. Although hK4 was found widely expressed in many human tissue types, indicating that it is not prostate specific in its expression, the highest expression level of hK4 was seen in the prostate. Therefore, detailed expression patterns and levels of KLK4 mRNA and hK4 protein in the normal prostate and prostatic diseases and histopathological lesions were investigated and reported for the first time in this study. Twelve benign prostatic hyperplasia (BPH), 19 adenocarcinoma (Gleason grade 2-5) and 34 bone metastases from prostate cancer were analysed. Using in situ hybridisation, the expression of KLK4 mRNA was detected in the cytoplasm of the secretory cells of both normal and diseased prostate tissue. KLK4 mRNA was also noted in both secretory and basal cells of PIN lesions, but the basal cells of normal glands were negative. Using the hK4 N-terminal and mid-region antipeptide antibodies, hK4 was predominantly localised in the cytoplasm of the secretory cells. The intensity of hK4 staining appeared lowest in normal and BPH, and increased in PIN lesions, high Gleason grade prostate cancer and bone metastases indicating the potential of hK4 as a histopathological marker for prostatic neoplasias. Further studies are required with a larger cohort to determine its utility as a clinical biomarker. Small foci of atypical cells, which were found within normal glands, were also intensely stained. Surprisingly, hK4 protein was found in the nucleus of the secretory cells (but not the basal cells) of high grade PIN and Gleason grade 3 prostate cancer. The detection of KLK4 mRNA and hK4 protein in PIN lesions and small foci of atypical cells suggests that up-regulation of KLK4 expression occurs early in the pathology of prostate carcinogenesis. The finding of basal cell expression is not typical for the kallikreins and it is not clear what role hK4 would play in this cell type. With the use of the hK4 C-terminal antipeptide antibody, the staining was mainly localised in the nuclei of the secretory cells of the prostate glands. Although the nuclear localisation was readily noted in more than 90% of epithelial cells of the prostate gland with the C-terminal antibody, no difference in staining intensity was observed among the histopathological lesions of the prostate. The prominent nuclear localisation with the C-terminal antipeptide antibody was also shown to be distributed throughout the nucleus by using confocal microscopy. Further, by using gold-labelled particles for electron microscopy, the intracellular localisation of these hK4 antipeptide antibodies was reported here for the first time. Similar to the immunohistochemical results, the cytoplasm was the major site of localisation with the N-terminal and mid-region antipeptide antibodies. To further characterise the involvement of KLK4/hK4 in human prostate cancer progression, the transgenic adenocarcinoma mouse prostate (TRAMP) model was used in this study. In this study, mouse KLK4 (also known as enamel matrix serine protease -1, EMSP-1) was shown to be expressed in the TRAMP prostate for the first time. Previous studies had only shown the developing tooth as a site of expression for EMSP-1. The level of EMSP-1 mRNA expression was increased in PIN and prostate cancer lesions of the TRAMP model, while negative or low levels of EMSP-1 mRNA were seen in normal glands or in control mouse prostate tissue. The normal mouse prostate did not stain with any the three hK4 antipeptide antibodies. hK4 N-terminal and mid-region antipeptide antibodies showed positive staining in the cytoplasm of the epithelial cells of PIN and cancer lesions of the mouse prostate. The C-terminal antipeptide antibody showed distinctively nuclear staining and was predominantly localised in the nuclei of the glandular cells of PIN and cancer lesions of the mouse prostate. The expression patterns of both the mRNA and protein level for mouse KLK4 strongly supported the observations of KLK4/hK4 expression in the human prostate and further support the utility of the TRAMP model. Overall, the findings in this thesis indicate a clear association of KLK4/hK4 expression with prostate cancer progression. In addition, several intriguing findings were made in terms of cellular localisation (basal as well as secretory cells; nuclear and cytoplasmic) and high expression in atypical glandular cells and PIN, perhaps indicating an early involvement in prostate disease progression and, additionally, utility as basal cell and PIN histological markers. These findings provide the basis for future studies to confirm the utility of hK4 as a biomarker for prostate cancer progression and identify functional roles in the different cellular compartments.
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Application of the Stimulus-Driven Theory of Probabilistic Dynamics to the hydrogen issue in level-2 PSA / Application de la Stimulus Driven Theory of Probabilistic Dynamics (SDTPD) au risque hydrogène dans les EPS de niveau 2.Peeters, Agnes 05 October 2007 (has links)
Les Etudes Probabilistes de Sûreté (EPS) de niveau 2 en centrale nucléaire visent à identifier les séquences d’événements pouvant correspondre à la propagation d’un accident d’un endommagement du cœur jusqu’à une perte potentielle de l’intégrité de l’enceinte, et à estimer la fréquence d’apparition des différents scénarios possibles.<p>Ces accidents sévères dépendent non seulement de défaillances matérielles ou d’erreurs humaines, mais également de l’occurrence de phénomènes physiques, tels que des explosions vapeur ou hydrogène. La prise en compte de tels phénomènes dans le cadre booléen des arbres d’événements s’avère difficile, et les méthodologies dynamiques de réalisation des EPS sont censées fournir une manière plus cohérente d’intégrer l’évolution du processus physique dans les changements de configuration discrète de la centrale au long d’un transitoire accidentel.<p>Cette thèse décrit l’application d’une des plus récentes approches dynamiques des EPS – la Théorie de la Dynamique Probabiliste basée sur les Stimuli (SDTPD) – à différents modèles de déflagration d'hydrogène ainsi que les développements qui ont permis cette applications et les diverses améliorations et techniques qui ont été mises en oeuvre.<p><p>Level-2 Probabilistic Safety Analyses (PSA) of nuclear power plants aims to identify the possible sequences of events corresponding to an accident propagation from a core damage to a potential loss of integrity of the containment, and to assess the frequency of occurrence of the different scenarios.<p>These so-called severe accidents depend not only on hardware failures and human errors, but also on the occurrence of physical phenomena such as e.g. steam or hydrogen explosions. Handling these phenomena in the classical Boolean framework of event trees is not convenient, and dynamic methodologies to perform PSA studies are expected to provide a more consistent way of integrating the physical process evolution with the discrete changes of plant configuration along an accidental transient.<p>This PhD Thesis presents the application of one of the most recently proposed dynamic PSA methodologies, i.e. the Stimulus-Driven Theory of Probabilistic Dynamics (SDTPD), to several models of hydrogen explosion in the containment of a plant, as well as the developed methods and improvements.<p> / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished
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Modelado y evaluación de prestaciones de redes de sensores inalámbricos heterogéneos con ciclo de trabajo síncronoPortillo Jiménez, Canek 02 September 2021 (has links)
[ES] Las redes de sensores inalámbricas (WSN) han experimentado un resurgimiento debido al desarrollo de la Internet de las Cosas (IoT). Una de las características de las aplicaciones de la IoT es la necesidad de hacer uso de dispositivos sensores y actuadores. En aplicaciones como automatización de edificios, de gestión energética, industriales o de salud, los nodos sensores que componen la WSN, transmiten información a un colector central o sink. La información es posteriormente procesada, analizada y utilizada para propósitos específicos. En cada una de estas aplicaciones, los dispositivos sensores pueden considerarse como parte de una WSN.
En ese sentido el modelado y la evaluación de las prestaciones en las WSN es importante, ya que permite obtener una visión más clara de su comportamiento, facilitando un adecuado diseño y una exitosa puesta en operación.
En el presente trabajo de tesis se han desarrollado modelos matemáticos para evaluar las prestaciones de WSN, los cuales están basados en Cadenas de Markov en Tiempo Discreto (DTMC). Los parámetros de prestaciones elegidos para la evaluación son: energía consumida promedio, eficiencia energética, caudal cursado y retardo promedio de los paquetes. Los resultados que se han obtenido han sido validados por medio de simulación basada en eventos discretos (DES).
Existen estudios de WSN en escenarios homogéneos, donde los nodos que componen la red inalámbrica son del mismo tipo y tienen las mismas características de operación. En estos análisis se definen WSN homogéneas compuestas por un nodo central o sumidero (sink), que recibe la información de los nodos sensores localizados alrededor, formando una célula o cluster. Estos nodos realizan las transmisiones en SPT (Single Packet Transmission), enviando un solo paquete por ciclo de transmisión.
Sin embargo, es posible encontrar, más ahora con el desarrollo de la IoT, escenarios donde coexisten distintos tipos de nodos, con características diferentes y, por tanto, con requerimientos de operación específicos. Esto da lugar a la formación de clusters cuyos nodos tienen aplicaciones distintas, desigual consumo de energía, diversas tasas de trasmisión de datos, e incluso diferentes prioridades de acceso al canal de transmisión. Este tipo de escenarios, que denominamos heterogéneos, forman parte de los escenarios estudiados en el presente trabajo de tesis.
En una primera parte, se ha desarrollado un modelo para evaluar las prestaciones de una WSN heterogénea y con prioridades de acceso al medio. El modelado incluye un par de DTMC de dos dimensiones (2D-DTMC) cada una, cuya solución en términos de la distribución de probabilidad estacionaria, es utilizada para determinar los parámetros de prestaciones. Se desarrollan, por tanto, expresiones cerradas para los parámetros de prestaciones, en función de la distribución estacionaria que se ha obtenido a partir de la solución de las 2D-DTMC.
En una segunda parte, se desarrolla un modelo analítico también pensado para escenarios heterogéneos y con prioridades, pero en el que los nodos de la WSN, cuando consiguen acceso al canal, transmiten un conjunto de paquetes en vez de uno solo como en el modelo de la primera parte. Estos dos modos de operación de los sensores los denominamos aggregated packet trans-
mission (APT) y single packet transmission (SPT), respectivamente. El número de paquetes que un nodo funcionando en APT trasmite cuando accede al canal es el menor entre un parámetro configurable y el número de paquetes que tuviera en la cola en ese momento. Este modo de operación consigue una mayor eficiencia energética y un aumento en el caudal cursado, además de una disminución en el retardo promedio de los paquetes.
En una tercera parte, se propone un nuevo procedimiento analítico para la determinación del consumo energético de los nodos que conforman una WSN. A diferencia de los métodos de cálculo anteriores, la nueva prop / [CA] Les xarxes de sensors sense fils (WSN) han experimentat un ressorgiment causa de al desenvolupament de la Internet de les Coses (IoT). Una de les característiques de IoT és la inclusió, en les seves aplicacions, de dispositius sensors i actuadors. En aplicacions com automatització d'edificis, de gestió energètica, industrials o de salut, els nodes sensors que componen la WSN, transmeten informació a un col·lector central o sink. La informació és posteriorment processada, analitzada i utilitzada per a propòsits específics. En cadascuna d'aquestes aplicacions, els dispositius sensors poden considerar com a part d'una WSN.
En aquest sentit el modelitzat i l'avaluació de l'acompliment en les WSN és important, ja que permet obtenir una visió més clara del seu comportament, facilitant un adequat disseny i una exitosa posada en operació.
En el present treball de tesi s'han desenvolupat models matemàtics per avaluar l'acompliment de WSN, els quals estan basats en Cadenes de Markov en Temps Discret (DTMC). Els paràmetres d'acompliment obtinguts per a l'avaluació són: energia consumida mitjana, eficiència energètica, cabal cursat i retard mitjà dels paquets. Els resultats que s'han obtingut, han estat validats per mitjà de simulació basada en esdeveniments discrets (DES).
Existeixen estudis de WSN en escenaris homogenis, on els nodes que componen la xarxa sense fils són de el mateix tipus i tenen les mateixes característiques d'operació. En aquests anàlisis prèvies es defineixen WSN homogènies compostes per un node central o embornal (sink), que rep la informació dels nodes sensors localitzats al voltant, formant una cèl·lula o cluster. Aquests nodes realitzen les transmissió en SPT (Single Packet Transmission), és a dir, enviant un sol paquet cada vegada que transmeten.
No obstant això, és possible trobar, més ara amb el desenvolupament de la IOT, escenaris on hi ha una coexistència de distints tipus de nodes, amb característiques diferents i, per tant, amb requeriments d'operació específics. Això dona lloc a formació de clusters els nodes tenen aplicacions diferents, desigual consum d'energia, diverses taxes de transmissió de dades, i fins i tot diferent prioritats d'accés a canal de transmissió. Aquest tipus d'escenaris, que anomenem heterogenis, formen part dels escenaris estudiats en el present treball de tesi.
En una primera part, s'ha desenvolupat un model per avaluar l'acompliment d'una WSN heterogènia i amb prioritats d'accés al medi. El modelitzat inclou un parell DTMC de dues dimensions (2D-DTMC), la solució en termes de la distribució estacionària de probabilitat, és utilitzada per obtenir posteriorment els paràmetres d'acompliment. Es desenvolupen, per tant, expressions tancades per a la determinació dels paràmetres d'acompliment, on és substituïda la distribució estacionària que s'ha obtingut a partir de la solució de les 2D-DTMC.
En una segona part, es desenvolupa un model, en el qual els nodes pertanyents a la WSN, poden transmetre els seus paquets en agregat (APT) en escenaris heterogenis i amb prioritats. A diferència del model anterior, on els nodes transmeten un paquet per cicle (SPT), en APT els nodes poden transmetre més d'un paquet. Això porta com a conseqüència una major eficiència energètica, a més d'un augment en el cabal cursat i disminució en el retard mitjana.
En una tercera part, es proposa un nou desenvolupament analític per a la determinació del consum energètic dels nodes que conformen una WSN. A diferència de les expressions utilitzades anteriorment per al càlcul del consum energètic, aquesta proposta alternativa permet obtenir resultats més precisos a través del desenvolupament d'expressions més intuïtives i sistemàtiques. Amb aquest nou procediment, es realitzen estudis energètics per WSN en escenaris homogenis i heterogenis. / [EN] Wireless sensor networks (WSN) have experienced a resurgence due to the development of the Internet of Things (IoT). One of the characteristics of IoT is the deployment of applications that require sensor devices and actuators. In applications such as building automation, energy management, industrial or health, the sensor nodes that make up the WSN transmit information to a central collector or sink. The information is processed, analyzed, and used for specific purposes. In each of these applications, the sensor devices can be considered part of a WSN.
In this sense, the modeling and performance evaluation of WSN is important, since it allows obtaining a clearer vision of their behavior, facilitating an adequate design and a successful operation.
In the present thesis, analytical models based on Discrete Time Markov Chains (DTMC) have been developed to evaluate the performance of WSN. The parameters defined for the performance evaluation are: average consumed energy, energy efficiency, throughput and average packet delay. The obtained results have been validated by means of discrete event simulation (DES).
There are studies of WSN in homogeneous scenarios, where the nodes that compose the WSN are of the same type and have the same operating characteristics. In these previous studies, homogeneous WSN are defined as a cell or cluster composed of a central node or sink, which receives the information from the sensor nodes located around it. These nodes operate in SPT (Single Packet Transmission), sending a single packet per transmission cycle.
However, it is possible to find, especially now with the development of the IoT, scenarios where different types of nodes coexist, although they have different characteristics or specific operational requirements. This results in the formation of clusters whose nodes have different applications, uneven power consumption, different data transmission rates, and even different priorities for access to the transmission channel. These types of scenarios, which we call heterogeneous, are part of the scenarios studied in this thesis work.
In the first part, a model has been developed to evaluate the performance of a heterogeneous WSN and with priorities to access a common channel. The model includes a two-dimensional DTMC pair (2D-DTMC), whose solution in terms of the stationary probability distribution is used to obtain the performance parameters. Closed expressions are provided for the determination of performance parameters of interest, given in terms of the stationary distribution of the 2D-DTMC.
In a second part, an analytical model is developed to evaluate the performance of a heterogeneous WSN, where nodes operate in aggregate packet transmission (APT) mode and deploy different channel access priorities. Un like the previous model, where the nodes transmit one packet per cycle (SPT) when they gain access to the channel, in APT the nodes can transmit a number of packets larger than one, that is the minimum between a configurable parameter and the number of packets in the packet queue of the node. This results in greater energy efficiency and throughput, while decreases the average packet delay.
In a third part, a new analytical model is proposed to determine the energy consumption of the nodes that make up a WSN. Unlike previous computation procedures, this alternative proposal is based on more intuitive and systematic expressions and allows to obtain more accurate results. With this new procedure, energy studies are performed for WSN in homogeneous and heterogeneous scenarios. / Este trabajo se ha desarrollado en el marco de los siguientes proyectos de investigación: Platform of Services for Smart Cities with Dense Machine to Machine Networks, PLASMA, TIN2013-47272-C2-1-R and New Paradigms of Elastic Networks for a World Radically Based on Cloud and Fog Computing, Elastic Networks, TEC2015-71932-REDT. También quisiera agradecer el apoyo recibido por parte de the European Union under the program Erasmus Mundus Partnerships, project EuroinkaNet, GRANT AGREEMENT NUMBER - 2014-0870/001/001 y La Secretaria de Educación Pública (México), bajo el Programa para el Desarrollo Profesional Docente: SEP-SES (DSA/103.5/15/6629). / Portillo Jiménez, C. (2021). Modelado y evaluación de prestaciones de redes de sensores inalámbricos heterogéneos con ciclo de trabajo síncrono [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/171275
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