Large Eddy Simulation of Mixing Layers

Mixing layers have numerous applications and are of importance in investigations about transition, turbulence and the behavior of different flows in mixing process. Therefore, inquiries about various setups of mixing layers are pretty beneficial. Planar mixing layers are a subset of this subject which are implemented in applications such as combustion furnaces, chemical lasers, the lip of an intake valve in an internal combustion engine and the trailing edge of a turbine blade. Understanding the details of mixing area is critical in terms of chemically reacting and combustion mixing flows. Here in this project, an investigation on the planar mixing layers in transition to turbulence is carried out both in 2D and 3D. Effects of the splitter plate’s trailing edge on the growth of the shear layer is investigated through simulations with different thicknesses of the splitter. Finally, use of an alternative turbulence model (WALE) as a substitute for Smagorinsky model with constant coefficient is put into consideration

Extraction and measurement of the Quercetin flavonoid of Prosopis farcta in Khouzestan climatic condition

Background and aims: Medicinal plants are a valuable resource for flavonoids extraction. Prosopis fracta is one of the plants with medicinal properties. Prosopis fracta was found in abundance in southern regions in Iran. Coersetin is medicinal substance found in the fruit of this plant. Quercetin is used in treatment of cancer and viral infections. This study was conducted to determine the Quercetin flavonoid in Prosopis fracta samples in different regions of Khuzestan. Methods: The Prosopis fracta fruit collected from different regions of Khuzestan (Susangerd, Ahvaz, Abadan, Mollasani, Behbahan and Ramhormoz). The beads were isolated from the fruit. Shell and the flesh were dried in an Oven. The dried materials were mixed and flavonoids extracted with a suitable solvent. The extract was injected into the High Performance Liquid Chromatography (HPLC) system. Then, the compound, Quercetin quantity and standard peak in each sample have been determined. Results: Based on the results, the Susangerd samples (0.0033 mg/ml) and Abadan (0.0008 mg/ml) have maximum and minimum levels of Quercetin flavonoid, respectively. Conclusions: Quercetin flavonoid extracted from Prosopis farcta fruits of Susangerd is richer than other regions of Khuzestan province. Therefore, it is recommended to use the Prosopis fracta fruit grown in Susangerd for extraction of the Quercetin flavonoid

Topic Modelling for Metadata Extraction and Generation from Norwegian Parliamentary Texts

Emnemodellering er prosessen med å identifisere abstrakte begreper i en samling av dokumenter. Det er en mye brukt teknikk for å ekstrahere meningsfull informasjon fra tekstdata. I denne masteroppgaven undersøker vi effektiveten til en rekke emneodelleringsarkitekturer: BERTopic, Top2Vec og LDA. Arkitekturene blir testet på en samling med transkriberte parlamentariske taler fra det norske Stortinget. Vi utforsker ulike aspekter ved emnemodellering, inkludert forbehandlingstrinn som fjerning av stoppord og valg av passende innlemningsmodeller. Evaluering av resultater er avgjørende for å kunne anvende emnemodelleringsteknikker på en effektiv måte. Imidlertid har de to primære metoder for evaluering, brukertesting og automatiske metrikker, klare begrensninger. Brukertesting er tidkrevende og har en lang tilbakemeldingsløkke på grunn av kravet om brukerdeltakelse. Automatiske metrikker er begrenset i forhold til deres forbindelse til menneskelig tolkningsevne. For å overvinne disse begrensningene, foreslår avhandlingen et nytt evalueringsrammeverk kalt TopicEval, som utnytter domenekunnskap for å kvalitativt analysere eksempler på emner ved bruk av ordskyrepresentasjoner. Dette rammeverket gjør det mulig for domeneeksperter å systematisk vurdere kvaliteten og tolkbarheten til emner innen ulike kategorier. Vi anvendte evalueringsrammeverket på praktiske bruksområder i de gjennomførte eksperimentene. Som inkluderer analysen av et stort tekstbasert datasett (NPL). Gjennom eksperimentene observerte vi nytten av evalueringsrammeverket for å vurdere kvaliteten på temaene generert av modellene. Videre sammenligner vi to metoder for automatisk emne tittel generering, NETL og BERTopic. Vi undersøker deres styrker og svakheter, med tanke på faktorer som relevans til dokumenter og domenekunnskap.Topic modelling is the process of identifying abstract concepts in a collection of documents. It is a widely used technique for extracting meaningful information from textual data. This thesis focuses on investigating the effectiveness of topic modelling architectures, namely BERTopic, Top2Vec, and LDA, in the context of Norwegian transcribed parliamentary speeches. The study explores various aspects of topic modelling, including preprocessing steps such as stopword removal and the selection of appropriate embedding models. Evaluating the performance of topic modelling techniques is crucial for their effective application. However, the two current primary methods in user testing and automatic metrics, have clear limitations. User testing has the limitation of requiring users, hence being time-consuming and having a long feedback loop. Automatic metrics have their limitations connected to their relation to human interpretability. To overcome these limitations, the thesis proposes a novel evaluation framework (TopicEval), that leverages expert domain knowledge to qualitatively analyse samples of topics using wordcloud representations. This framework enables domain experts to systematically assess the quality and interpretability of topics across a variety of categories. We applied the evaluation framework to practical use cases in the experiments conducted, including the analysis of a large-scale textual dataset (NPL). Through the experiments, we observed the usefulness of the evaluation framework in assessing the quality of topics generated by models. Moreover, we address the challenge of automatic topic labelling and compare two methods, NETL and BERTopic, for generating topic labels. We examine their strengths and weaknesses, considering factors such as coherence, relevance to documents, and domain knowledge

Microleakage comparison of glass-ionomer and white mineral trioxide aggregate used as a coronal barrier in nonvital bleaching

Objectives: There is some evidence that the pH at the root surface is reduced by intracoronal placement of bleaching pastes, which is known to enhance osteoclastic activity. Therefore, it is recommended that a protective barrier be used over the canal filling to prevent leakage of bleaching agents. Glass-ionomer (GI) is commonly used as a coronal barrier before nonvital bleaching. Because mineral trioxide aggregate (MTA) creates high alkalinity after mixing with water, using MTA as a protective barrier over the canal filling may not only prevent leakage of bleaching agents and microorganisms, but may prevent cervical resorption. The aim of this study was to evaluate sealing ability of white mineral trioxide aggregate (WMTA) as a coronal barrier before nonvital bleaching. Study design: Root canals of one hundred thirty human maxillary incisors were instrumented and filled with gutta-percha without sealer. Gutta-percha was removed up to 3 mm below the cementoenamel junction (CEJ). The teeth were randomly divided into six experimental groups of 20 teeth each and two control groups of 5. In three experimental groups, WMTA was packed into the canal to the level of CEJ. In the remaining experimental groups, glass-ionomer (GI) was used as a coronal barrier. After a 24-hour incubation period, one of the following three bleaching agents was placed in the access cavity of each of the WMTA or GI groups. These three bleaching agents were 30% hydrogen peroxide, sodium perborate mixed with 30% hydrogen peroxide, and sodium perborate mixed with distilled water. The bleaching agents were replaced every 3 days for three times. In the positive controls, no coronal barrier was used. In the negative controls, all the tooth surfaces were covered by two layers of nail varnish. Microleakage was evaluated using protein leakage test. Statistical analyses were performed with the Kruskal-Wallis and Mann-Whitney tests. Results: The experimental groups showed minimum leakage which was not significantly more than tha in the negative controls. There was no statistically significant difference in leakage between the experimental groups (p<0.05). Conclusions: This study indicated that different bleaching agents have no effect on sealing ability of WMTA. © Medicina Oral S. L

Effect of alkaline ph on sealing ability of white mineral trioxide aggregate

Objectives: The aim of this study was to evaluate microleakage of white mineral trioxide aggregate (WMTA) after its exposure to a range of alkaline environments during hydration. Study Design: Seventy single-rooted teeth were divided into 4 experimental and 2 control groups. All the teeth were instrumented, and their apices were resected. Root-end cavities were filled with WMTA in the experimental groups. In the control groups, root-end cavities were not filled. Root-end fillings were exposed to alkaline environments with pH values of 7.4, 8.4, 9.4, or 10.4 for 3 days. Microleakage was evaluated by bovine serum albumin. Evaluations were carried out at 24-hour intervals for 80 days. Data were analyzed by one-way analysis of variance and a post hoc Tukey test at the 0.05 level of confidence. Results: The number of days (mean ± standard deviation) needed for color change at pH values of 7.4, 8.4, 9.4, and 10.4 were 78.53 ± 5.68, 80.00 ± 0.00, 68.93 ± 19.00, and 34.46 ± 12.73, respectively. The time needed for leakage to occur was significantly shorter in samples stored at a pH value of 10.4 (P<0.001). Conclusions: Within the limits of this study, it can be concluded that pH values greater than 9.4 may jeopardize the sealing ability of WMTA during hydration. © Medicina Oral S. L

Coordinated AC/DC Microgrid Optimal Scheduling

This paper proposes a coordinated optimal scheduling model for hybrid AC/DC microgrids. The objective of the proposed model is to minimize the total microgrid operation cost when considering interactions between AC and DC sub-systems of the microgrid network. Nonlinear power flow equations for AC and DC networks have been linearized through a proposed model to enable formulating the problem by mixed integer linear programming (MILP) which expedites the solution process and ensures better solutions in terms of optimality. The proposed model is tested on the modified IEEE 33-bus test system. Numerical simulations exhibit the merits of the proposed coordinated AC/DC optimal scheduling model and further analyze its sensitivity to various decisive operational parameters.Comment: 2017 North American Power Symposium (NAPS), Morgantown, WV, Sep 201

FATIGUE BEHAVIOR OF HOT MIX ASPHALT MODIFIED WITH NANO AL2O3 – AN EXPERIMENTAL STUDY

Nanotechnology is one of the most important research areas and is presented in the vast fields of knowledge such as road construction industry has been surrounded. This paper has focused on the potential benefits of nano particles for modification of asphalt mixtures. Nano Al2O3 due to its unique properties can improve the dynamic characteristics of hot mix asphalt. Fatigue life of asphaltic samples is determined with indirect tensile fatigue tests by using of UTM. The results show that fatigue life of modified asphalt mixtures in compare with conventional mix is significantly increased. Beside, based on experimental results and numerical analyses, a new model is presented for prediction the fatigue behavior of asphalt mixtures modified with nano Al2O3. This model can completely characterized the fatigue performance of modified asphalt under dynamic loading conditions and different temperatures