Numerical Experiments of Hurricane Impact on Vertical Mixing and De-Stratification of the Louisiana Shelf Waters

The numerical model FVCOM (Finite Volume Community Ocean Model) was applied to study the effects of Hurricane Katrina on the vertical mixing over the Louisiana shelf and the process of post-storm re-stratification. Wind field from Hurricane Katrina was generated using a single vortex analytical model and was evaluated using available wind measurements over the shelf. Simulations of shelf circulation under Hurricane Katrina were done through several numerical tests to find the best approach for treating vertical eddy viscosity. Model results for the shelf during Katrina demonstrated opposite currents between surface and bottom for most of the shelf area. Results also show current intensification between the eye and the Birds-foot delta, where current speed reached ~ 3.5 m/s at one time. Shelf-wide mixing and re-stratification during and after Katrina were studied by examining the salt and heat transports. Climatological salinity and temperature profiles for August from NOAA were used as the initial conditions. Model performance in simulating water temperature was evaluated using the cloud transparent microwave band SST data (OI-MW) along the shelf break. Model was also evaluated for the mixed layer depth (MLD) calculated from model results which were compared with that from the OI-MW SST data and a theoretical model. During Katrina, the SST decreased up to 1C for areas outside of the 1-1.5 Radius of maximum wind (RMW), while inside the RMW and west of the Birds-foot delta 2-3.5 C. Consequently, the mixed layer depth (MLD) left of the 1-1.5 RMW region was smaller than 10 meter. Inside this region the MLD was up to 40 meters. By inspecting the mixing and re-stratification pattern using the model outputs, conceptual models for water column mixing during the hurricane and re-stratification were proposed. It was concluded that the complete recovery of the water column temperature was not achieved even after 14 days following the landfall and it is likely that the effect of solar radiation may qualitatively change the conclusion. Hence, the effect of solar insolation on the shelf heating was simulated separately for non-hurricane summertime conditions. This simulation demonstrated the significant effect of solar insolation on the shelf heating and stratification of the water column

Simulating hypervelocity impact effects on structures using the smoothed particle hydrodynamics code MAGI

Analysis of interaction occurring between space debris and orbiting structures is of great interest to the planning and survivability of space assets. Computer simulation of the impact events using hydrodynamic codes can provide some understanding of the processes but the problems involved with this fundamental approach are formidable. First, any realistic simulation is necessarily three-dimensional, e.g., the impact and breakup of a satellite. Second, the thickness of important components such as satellite skins or bumper shields are small with respect to the dimension of the structure as a whole, presenting severe zoning problems for codes. Thirdly, the debris cloud produced by the primary impact will yield many secondary impacts which will contribute to the damage and possible breakup of the structure. The problem was approached by choosing a relatively new computational technique that has virtues peculiar to space impacts. The method is called Smoothed Particle Hydrodynamics

Space debris characterization in support of a satellite breakup model

The Space Kinetic Impact and Debris Branch began an ambitious program to construct a fully analytical model of the breakup of a satellite under hypervelocity impact. In order to provide empirical data with which to substantiate the model, debris from hypervelocity experiments conducted in a controlled laboratory environment were characterized to provide information of its mass, velocity, and ballistic coefficient distributions. Data on the debris were collected in one master data file, and a simple FORTRAN program allows users to describe the debris from any subset of these experiments that may be of interest to them. A statistical analysis was performed, allowing users to determine the precision of the velocity measurements for the data. Attempts are being made to include and correlate other laboratory data, as well as those data obtained from the explosion or collision of spacecraft in low earth orbit

Olving tri-level linear programming problem by a novel hybrid algorithm

This paper presents a revised hybrid algorithm to solve a tri-level linear programming problem, a generalization of a bi-level one, involving three decision makers at the upper, middle, and lower levels. The decision-making priority is from top to bottom and the decision of each decision maker affects the decision space of others. A hybrid algorithm has been already proposed to solve this problem, but it does not ensure to converge whereas the proposed novel revised algorithm lacks this drawback and ensures convergence.Publisher's Versio

The Analysis of the Basics of Gerard Genette’s Intertextuality in Farhad Hassanzadeh's The Bambak Ship’s Scorpions for Young Adults

The study of relationships between texts is one of the approaches to the study of literary works through which important information can be obtained from the text. Among the various literary theories that have dealt with the relationship between texts, transtextuality analyzes the text in this respect. This theory was first proposed by Gerard Genette, a French theorist and structuralist. Transtextuality has five forms: Paratextuality, intertextuality, architextuality, metatextuality, and hypertextuality, and includes an extensive study of relationships of a text with its para-elements, previous or contemporary texts, texts that have criticized and interpreted and have taken a step towards confirming or denying it; moreover, it includes the relationship of a text to the genre or genres in which the text is formed, and finally to the texts from which the text is taken. Farhad Hassanzadeh is a prolific writer with a specific style in children and young adult literature who has over 80 works on various subjects. He has received numerous national and international awards. Among his important and famous works, we can mention This Weblog Is Being Turned Over, Namaki And the Spectacled Snake, The Moonlight Guest, Call me Ziba, etc. This study intends to read Farhad Hassanzadeh's The Bambak Ship’s Scorpions through intertextuality which is one of the five forms of transtextuality and to identify the pretexts of interest to the author. In the following, it will be clear that the author has chosen the pretexts of the work purposefully and these pretexts have been effective in selecting some elements of the story. The author has also taken special care in using pretexts of popular culture such as proverbs and allusions, popular songs of the time, and slogans of the revolution. For this reason, the presence of this pretext in the work has a high frequency

Are Electricity Price Area Differentials (EPADs) good price forecasts?

Grunnet kapasitetsbegrensninger i det nordiske kraftnettet forholder ikke markedsaktører seg til den overordnede systemprisen for Norden, men til lokale områdepriser. For å beskytte seg mot prisrisiko i områdeprisene kan aktørene innta posisjoner i Electricity Price Area Differentials (EPADs) som er forwardkontrakter skrevet på differansen mellom områdepris og systempris. EPAD-markedet er preget av lavt volum og høye transaksjonskostnader, og det finnes lite eksisterende litteratur om temaet. Vi ønsker å bidra til fagfeltet med en empirisk analyse om hvorvidt månedlige EPAD-kontrakter for anmeldingsområdene SE3 (Stockholm), DK1 (Aarhus) og NO1 (Oslo) har vært gode prognoser for fremtidig differansepris. Vi velger å måle i hvilken grad EPAD-prognosene er gode ved å først sammenligne de mot tre andre konkurrentmodeller før de så måles på tvers av anmeldingområdene. Fremgangsmåten i analysen har vært å vurdere EPAD-kontraktenes prognoseegenskaper ved hjelp av deskriptiv statistikk, regresjonskoeffisienter, samt evalueringsmetrikkene RMSE og MAE. På bakgrunn av månedlige observasjoner fra 2013 til 2020 finner vi at samtlige EPAD-kontrakter i utvalget er forventningsrette på gjennomsnittet, men at det likevel er stor variasjon i resultatene. Tre av fire prognosemodeller for NO1 utkonkurrerer samtlige prognoser for SE3 og DK1 på gjennomsnittlig prognoseavvik. Vi finner at EPAD-prognosene utkonkurrer andre prognosemodeller på nær samtlige prestasjonsmetrikker innad prisområdene, med unntak av DK1 som presterer dårligere enn differanseprognosen på gjennomsnittet. I tillegg til å svare på hvorvidt kontraktene inneholder tilstrekkelig informasjon om system- og områdeprisene reiser oppgaven spørsmålet om EPAD-kontrakter tilfredsstiller behovet for prissikring eller om det foreligger behov for instrumenter skrevet direkte på områdeprisene.Due to capacity constraints in the Nordic power grid, market participants do not relate to the overall system price for the Nordic region, but to local area prices. To hedge against price risk in area prices, participants may use Electricity Price Area Differentials (EPADs) which are forward contracts that cover the difference between area price and system price. The market for EPADs is characterized by low volume and high transaction costs, and there is little existing literature on the subject. We want to contribute to the field with an empirical analysis of whether monthly EPAD contracts for the areas SE3 (Stockholm), DK1 (Aarhus) and NO1 (Oslo) have been good forecasts for future prices. We choose to measure the extent to which the EPAD forecasts are good by first comparing them with three other competitor models before they are then measured across the areas. The approach in the analysis has been to assess the EPAD contract's forecasting properties using descriptive statistics, regression coefficients, and the evaluation metrics RMSE and MAE.submittedVersionM-Ø

Optimized Er: YAG Laser Irradiation Distance to Achieve the Strongest Bond Strength Between Orthodontic Brackets and Zirconia-Ceramics

Introduction: In recent decades zirconium oxide has been introduced in the field of dentistry as a high-strength ceramic. Unlike its mechanical advantages, however, due to its inert chemical properties, it bonds poorly to other substrates, so improving bonding strength to an adhesive material is necessary.Methods: In this experimental study, 70 ceramic zirconia blocks were prepared and distributed randomly among 7 groups. Then the shear bond strengths were determined and the samples were examined by a scanning electron microscope (SEM). Statistical analysis was performed by one-way ANOVA and multiple Tukey comparisons.Results: One-way analysis of variance (ANOVA) showed that laser irradiation distance has a significant effect on orthodontics brackets bond strength to zirconia-ceramics. Based on the Tukey post hoc test, each group was compared with other groups and the contact mode and 2 mm distance groups showed significantly higher bond strength than other groups (P-value <0.05).Conclusion: Orthodontic bracket bond strength to zirconia-ceramics will be reduced by increasing Er: YAG laser irradiation distance from samples. The highest bond strength will be achieved when the laser irradiation distance is 2 mm or when the laser beam is in contact with samples.

Sistemas Hipertexto & Hipermédia - Reflexão, Ensino e Arte

Neste artigo começa por caracterizar-se o desenvolvimento dos sistemas hiper-texto/hipermédia associado ao paradigma da representação mental. Procura-se analisar o fundamento da atitude de mimésis entre os referidos sistemas e as representações internas do indivíduo no processamento de informação. Seguidamente, destaca-se o papel das tecnologias hipertexto/hipermédia no sistema educativo e o impacto inerente à sua implementação. Inclui, no final, uma reflexão sobre a cultura hipertexto/hipermédia e as suas repercussões no mundo da arte