Application of orthogonal neighborhood preserving projections and two dimensional hidden Markov model for the degradation evaluation of rolling elements bearings

An effective degradation indicator created from the general features is still a hotspot for the condition monitoring of bearing. To cover the shortage of the general features based indicator, some new indicators are built using multiple general features extracted from the original vibration signal without considering the internal relevancy among the features. To address that problem, a new indicator is proposed using the Orthogonal Neighborhood Preserving Projections (ONPP) and 2-Dimensional Hidden Markov Model (2-D HMM). With the ability of keeping the local structure of data set, Orthogonal Neighborhood Preserving Projections is used to obtain the low dimensional features with the main information remained. Unlike 1-Dimensional data-processing algorithm that commonly converts the multiple features into a vector to deal with the high-dimensional data with the integral property of the multiple features considered only, 2-Dimensional Hidden Markov Model not only take the relevance between the individuals of fault features into consideration but also capture the global characteristics of the multiple features. Then a likelihood probability based health assessment indication can be constructed by combing 2-D HMM with the data pre-processed by ONPP. The experiment results indicate that the proposed indicator show great abilities to make degradation performance of the bearing and is sensitive to incipient defects

Optical investigations on Diesel spray dynamics and in-flame soot formation

En las últimas décadas ha avanzado mucho la comprensión científica sobre el proceso de combustión de los chorros diesel de inyección directa gracias al desarrollo de todo tipo de técnicas e instalaciones ópticas. Además, se han desarrollado y mejorado una gran cantidad de modelos de Dinámica de Fluidos Computacional (CFD), los cuales se usan para el desarrollo de motores altamente eficientes y con bajas emisiones. Sin embargo, debido a la complejidad de los procesos físicos y químicos involucrados en este proceso de combustión, así como a las limitaciones significativas de los experimentos, aún hay muchas cuestiones sin responder: ¿Cómo afecta la combustión a la dinámica del chorro? ¿Cómo cuantificar de forma efectiva la cantidad de hollín y la temperatura del mismo en la llama? ¿Cómo afecta el flujo del aire y las inyecciones partidas al desarrollo del chorro y a la formación de hollín en condiciones no quiescente? Para ayudar a resolver las preguntas planteadas, el objetivo de este trabajo se pone en investigar al dinámica del chorro y la formación de hollín de los chorros Diesel de inyección directa en condiciones quiescentes y no quiescentes por medio de diferentes técnicas ópticas. El trabajo se ha dividido en dos bloques principales. El primero está centrado en el estudio de las modificaciones inducidas por la combustión en la dinámica del chorro, así como la caracterización de la formación de hollín en la llama, todo ello en condiciones quiescentes. Dichas condiciones son proporcionadas por una maqueta de flujo continuo a alta presión y temperatura. La expansión radial y axial del chorro reactivo se ha investigado usando n-dodecano, n-heptano y una mezcla binaria de combustibles primarios de referencia (80% n-heptano y 20% iso-octano en masa), basándose en una base de datos existente medida mediante visualización de schlieren. Se ha estudiado tanto el papel de las condiciones de operación como las propiedades del combustible. A continuación se ha desarrollado por primera vez una técnica combinada de extinción-radiación, aplicada a la medida de hollín en llamas diesel. Gracias a esta técnica, tanto la fracción volumétrica de hollín como la temperatura se obtuvieron simultáneamente considerando los efectos de la autoabsorción en la radiación. Todo este trabajo se ha desarrollado dentro del marco de actividades de la Engine Combustion Network (ECN). El segundo bloque corresponde a la caracterización de la dinámica del chorro y de la formación de hollín en condiciones no quiescentes, que ocurren en la cámara de combustión de un motor monocilíndrico de dos tiempos con accesos ópticos. En esta parte, se ha llevado a cabo en primer lugar la visualización del chorro para una inyección única en condiciones no-reactivas y reactivas. Se han aplicado la visualización simultánea de schlieren y de la quimioluminiscencia del radical OH* para obtener la penetración del chorro y la longitud de despegue de la llama, mientras que la visualización de la extinción de ombroscopía difusa (DBI) se ha aplicado para cuantificar la formaciónde hollín. Los resultados se han comparado con los de la base de datos de la Engine Combustion Network antes mencionados, para estudiar los efectos del movimiento del aire inducido por el movimiento del pistón sobre el desarrollo del chorro y del hollín. Finalmente, se han usado diferentes estrategias de inyección partida para estudiar cómo la primera inyección afecta a los procesos de mezcla y a formación de hollín de la segunda, al cambiar el tiempo de separación entre ambos eventos de inyección o la cantidad inyectada en el primer pulso.In recent decades, the scientific understanding of the combustion process of direct injection diesel spray has progressed a lot, thanks to the development of all kinds of optical facilities and techniques. In addition, a large amount of efficient and accurate Computational Fluid Dynamics (CFD) models, which are used for the design of highly efficient, low emission engines has been developed and improved. However, because of the complexity of the physical and chemical process involved in this combustion process, as well as significant experimental limitations and uncertainties, there are still a lot of remaining questions: How does combustion affect spray dynamics? How can in-flame soot amount and soot temperature be quantified effectively? How do the airflow and split-injection affect spray development and soot formation under non-quiescent conditions? To help solve these raised questions, the objective of this work is set to investigate the spray dynamics and soot formation process of direct injection diesel sprays under both quiescent and non-quiescent conditions by means of different optical techniques. The work has been divided into two main blocks. The first one is focused on the study of combustion-induced modifications in spray dynamics, as well as the characterization of in-flame soot formation under quiescent conditions. The quiescent conditions are provided by a kind of high-temperature high-pressure constant flow vessel. The radial and axial reacting spray expansion were investigated using n-dodecane, n-heptane and one binary blend of Primary Reference Fuels (80% n-heptane and 20% iso-octane in mass) based on an existing database from Schlieren imaging technique. Both operating conditions and fuel properties on this combustion-induced expansion were studied. Next, a combined extinction-radiation technique was first developed and applied in diesel spray soot measurement. Thanks to this technique, both the in-flame soot volume fraction and temperature were obtained simultaneously by considering the self-absorption effect on radiation. All this work has been carried out within the framework of activities of the engine combustion network (ECN). The second block corresponds to the characterization of spray dynamics and soot formation under non-quiescent conditions, which occur within the combustion chamber of a single-cylinder two-stroke optical engine. In this part, the spray visualization for single-injection under both non-reacting and reacting operating conditions was conducted first. Schlieren and OH * chemiluminescence were simultaneously applied to obtain the spray tip penetration and flame lift-off length, while the Diffuse Back Illumination (DBI) extinction imaging was applied to quantify the instantaneous soot formation. Results were compared with Engine Combustion Network database mentioned above to study the airflow effects induced by piston movement on spray and soot development. Finally, different split-injection strategies were used to study how the first injection affects the mixing and soot formation processes of the second one, by changing the dwell time between both injection events or the first injection quantity.En les últimes dècades ha avançat molt la comprensió científica sobre el procés de combustió dels dolls dièsel d'injecció directa gràcies al desenvolupament de tot tipus de tècniques i instal·lacions òptiques. A més, s'han desenvolupat i millorat una gran quantitat de models de Dinàmica de Fluids Computacional (CFD), els quals s'usen per al desenvolupament de motors altament eficients i amb baixes emissions. No obstant açò, a causa de la complexitat dels processos físics i químics involucrats en aquest procés de combustió, així com de les limitacions significatives dels experiments, encara hi ha moltes qüestions sense respondre: Com afecta la combustió a la dinàmica del doll? Com quantificar de forma efectiva la quantitat de sutge i la temperatura del mateix en la flama? Com afecta el flux de l'aire i les injeccions partides al desenvolupament del doll i a la formació de sutge en condicions no quiescents? Per a ajudar a resoldre les preguntes plantejades, l'objectiu d'aquest treball es posa a investigar al dinàmica del doll i la formació de sutge dels dolls Dièsel d'injecció directa en condicions quiescents i no quiescents per mitjançant diferents tècniques òptiques. El treball s'ha dividit en dos blocs principals. El primer està centrat en l'estudi de les modificacions induïdes per la combustió en la dinàmica del doll, així com la caracterització de la formació de sutge en la flama, tot açò en condicions quiescents. Aquestes condicions són proporcionades per una maqueta de flux continu a alta pressió i temperatura. L'expansió radial i axial del doll reactiu s'ha investigat usant n-dodecà, n-heptà i una mescla binària de combustibles primaris de referència (80% n-heptà i 20% iso-octà en massa), basant-se en una base de dades existent mesura mitjançant visualització de schlieren. S'ha estudiat tant el paper de les condicions d'operació com les propietats del combustible. A continuació s'ha desenvolupat per primera vegada una tècnica combinada d'extinció-radiació, aplicada a la mesura de sutge en flames dièsel. Gràcies a aquesta tècnica, tant la fracció volumètrica de sutge com la temperatura es van obtenir simultàniament considerant els efectes de l'autoabsorció en la radiació. Tot aquest treball s'ha desenvolupat dins del marc d'activitats de la Engine Combustion Network (ECN). El segon bloc correspon a la caracterització de la dinàmica del doll i de la formació de sutge en condicions no quiescents, que ocorren en la cambra de combustió d'un motor monocilíndric de dos temps amb accessos òptics. En aquesta part, s'ha dut a terme en primer lloc la visualització del doll per a una injecció única en condicions no-reactives i reactives. S'han aplicat la visualització simultània de schlieren i de la quimioluminescència del radical OH* per a obtenir la penetració del doll i la longitud d'enlairament de la flama, mentre que la visualització de l'extinció d'ombroscopia difusa (DBI) s'ha aplicat per a quantificar la formaciónde sutge. Els resultats s'han comparat amb els de la base de dades de la Engine Combustion Network abans esmentats, per a estudiar els efectes del moviment de l'aire induït pel moviment del pistó sobre el desenvolupament del doll i del sutge. Finalment, s'han usat diferents estratègies d'injecció partida per a estudiar com la primera injecció afecta als processos de mescla i a formació de sutge de la segona, en canviar el temps de separació entre tots dos esdeveniments d'injecció o la quantitat injectada en el primer pols.Xuan, T. (2017). Optical investigations on Diesel spray dynamics and in-flame soot formation [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/94626TESI

Seismic chronostratigraphy for reservoir characterization : modeling and applications

The assumption of the chronostratigraphic significance of seismic reflections serves as a fundamental premise in interpreting stratigraphy from seismic images. This hypothesis proposed in 1977 was initially applied to delineate depositional sequences as the basic interpretive unit, and then to reconstruct Wheeler Diagram and regional sea level curves. After a further comparison against with global eustatic events, these regional curves can further facilitate predicting the age, distribution, and facies of depositional sequence before drilling in a seismic-covered area during petroleum exploration. With a boom in reservoir-level seismic applications, for obtaining significant high frequency sequence (HFS) surfaces as the bounding surfaces in static reservoir model construction, this fundamental assumption was inevitably extended to characterize HFS and even high-frequency cycles (HFC) during seismic reservoir characterization. For an ultimate improvement in constructing reservoir-bounding surfaces, the author targeted at evaluating the validity of this fundamental assumption as applied to high-order seismic stratigraphy. The author conducted the entire project via the forward seismic modeling upon geologic models with known chronostratigraphic relationship. Besides, these input models carefully honor the reservoir geology for meaningful discussions on (1) shallow marine siliciclastic reservoirs in Starfak Field, GoM, (2) shallow-water mixed carbonate/clastic Upper San Andres-Grayburg reservoirs in Permian Basin, and (3) shallow-water carbonate Abo shelf margin-Clear Fork platform in Permian Basin. This study has achieved three-fold contributions. On the aspect of realistic geocellular, property and seismic modeling at the reservoir scale, the author integrated high-resolution sequence stratigraphic framework, published 3D depositional model, intra-facies heterogeneity in 3D modeling to selectively apply advanced geostatistical methods to model hierarchical heterogeneity. Subsequently, the author proposed an evaluation scheme with a defined parameter ('time-correlation error/TCE') to assess HFS-scale reservoir-bounding surfaces. These assessments revealed an interactive influence from (1) stratal geometry, (2) lateral lithofacies variation, (3) lithofacies-sonic velocity relationship in pure- versus mixed-lithology successions, (4) intra-facies heterogeneity, and (5) seismic frequency. Finally, based on these forward modeling results, the author proposed a decision tree to determine valid interpretation strategy in seismic chronostratigraphic correlation in scenarios with geoscientists’ expert knowledge and recommended an attribute-driven volumetric picking scheme to improve published algorithms for scenarios without prior knowledge.Geological Science

ONCOGENE-INDUCED ALTERED DNA REPLICATION DYNAMICS

Oncogene Induced Senescence (OIS) is a tumor suppressive barrier that blocks cell cycle permanently. OIS results from a robust DNA damage response (DDR) activation due to oncogene-induced hyper-proliferation. By performing a whole genome analysis of DNA replication dynamics occurring upon oncogene activation, I discovered that oncogene activation alters DNA replication by increasing replication fork speed and fork stalling, while decreasing the frequency of replication initiation. This is accompanied by a prompt DDR activation. As cells approach senescence the frequency of initiation increases, the level of fork stalling and fork speed decreases. Oncogene activation leads to DNA replication stress mainly at fragile sites and since telomeres resemble fragile sites, I then demonstrated that oncogene activation impairs telomere replication, by increasing fork stalling at telomeres. This is accompanied by increased fragile telomeres, stochastic telomeric attrition and persistent telomeric DDR. These results revealed a novel link between oncogene activation and telomere dysfunction, refining the model underlying OIS establishment. Oncogene activation increases Reactive Oxygen Species (ROS). Beyond their toxicity, ROS are essential second messengers mediating mitogenic signalling. We discovered that oncogene-induced ROS is mediated by the NADPH oxidase NOX4. Upon oncogene activation, NOX4 pharmacological inhibition blocks ROS production, resulting in fork speed reduction and differential regulation of local replication origin initiation. These results revealed a fundamental role of NOX4 and ROS in mediating oncogene-induced hyperproliferation. Polycomb repressive complexes (PRCs) repress genes involved in development, proliferation and differentiation by EZH2-mediated H3K27 trimethylation. Recent independent studies revealed a more direct PRCs role on S phase progression and DNA replication. We show that EZH2 KO leads to impairment of cell cycle progression, with cells blocked at G1/S transition. Furthermore EZH2 KO impairs DNA replication, by reducing fork speed, increasing the frequency of initiation and fork stalling, demonstrating that PRCs deficiency leads to replication stress

Identifisering av RseP som reseptor for hybrid bakteriocin H1 i voksende patogen Staphylococcus haemolyticus

Staphylococcus haemolyticus is an emerging pathogen which may transfer multi-drug resistance genes to highly virulent Staphylococcus species. S. haemolyticus is a biofilm-producing bacterium and one of the most frequent isolates of nosocomial infections associated with implanted medical devices, such as catheter. To this date there are only a few therapeutic options that can stop this bacterium, including the last resort antibiotic, vancomycin and teicoplanin, for which resistance have already been reported. This study shows that an alternative antimicrobial agent has great potential to inhibit this pathogen. Hybrid bacteriocin H1 consisting of N-terminal part of EntK1 and C-terminal part of EntEJ97, exhibits strong activity against S. haemolyticus. A combination of bacteriocin H1 with garvicin KS displays greater antibacterial activity against S. haemolyticus and is promising in inhibiting resistant mutants, which appear to be the main problem in H1 application. The aim of this study was to reveal the nature that indicates the specificity of H1 toward S. haemolyticus. The Zn-dependent protease RseP in S. haemolyticus was established as a receptor for bacteriocin H1. This is based on the fact that the S. haemolyticus gene rseP was heterologously-expressed in naturally H1 resistant Lactobacillus plantarum WCFS1 and the resulting transformant became highly susceptible to H1. RseP isolated from resistant mutants were sequenced in order to verify the nature of the bacterial resistance to H1. Interestingly, obtained data showed intact rseP gene in all mutants. WGS analysis was a conclusive step in this study and indicated mutation in a putative Ecs ABC transporter. Similar discoveries from previous investigations suggest the influence of Ecs transporter on RseP activity at protein level. One might speculate that Ecs protein inhibits RseP interaction with bacteriocin by blocking its activity. However, the results of this study do not allow for specific conclusions on correlation between Ecs and RseP. Further studies of between RseP and Ecs interaction with bacteriocin H1 are required.Staphylococcus haemolyticus kan overføre gener for multi-resistansen til sterkt virulente Staphylococcus arter. S. haemolyticus er en biofilm produserende bakterie og et av de hyppigste isolatene i nosokomiale infeksjoner, og er ofte forbundet med implantert medisinsk utstyr som for eksempel kateter. Til dags dato er det bare noen få terapeutiske alternativer som kan hindre denne bakterien. Dette inkluderer også bruk av antibiotika som en «last resort», selv bakterier som er resistente mot en slik behandling allerede er rapportert. Denne studien viser at et alternativt antimikrobielmiddel har stort potensiale for å hemme dette patogenet. Hybrid bakteriosin H1 består av N-terminal part av EntK1 og C-terminal part av EntEJ97 og viser sterk aktivitet mot S. haemolyticus. En kombinasjon av de to lederløse bakteriosinene H1 og garvisin KS utviser stort antibakteriell aktivitet mot S. hamolyticus og er lovende for å hemme resistente mutanter, som ser ut til å være hovedproblemet i H1 applikasjonen. Målet med denne studien var å avsløre naturen som angir spesifisiteten til H1 mot S. haemolyticus. Den Zn-avhengige proteasen RseP i S. haemolyticus ble etablert som reseptor for bakteriosin H1. Detter er basert på det faktum at S. haemolyticus - genet rseP ble heterologt uttrykt i naturlig H1-resistent Lactobacillus plantarum WCFS1 og den resulterende transformanten ble svært sensitiv til H1. RseP isolert fra resistente mutanter, ble sekvensert for å verifisere naturen av bakteriell resistans mot H1 og variasjoner i fenotype ved stressrespons. Interessant nok, var rseP i alle mutanter. WGS analysen var et avgjørende trinn i dette arbeidet, og indikerte delesjoner i Ecs ABC transporter. Tilsvarende funn fra tidligere studier antyder en påstått effekt av Ecs transporter på RseP-aktivitet på proteinnivå. Man kan spekulere at Ecs protein hemmer RseP interaksjon med bakteriosin H1 ved å blokkere dets aktivitet. Resultatene fra denne studien tillater ikke konkrete konklusjoner om sammenheng mellom Ecs og RseP. Videre studier om interaksjonen mellom RseP og Ecs med bakteriosin H1 er nødvendigM-BIOTE