A priori Analysis of Subgrid-Scale Heat Flux Vectors in High Pressure H2/O2 Mixing and Reacting Shear Layers

A Direct Numerical Simulation (DNS) database of supercritical, transitional H2/O2 mixing and reacting shear layers is analyzed in an a priori manner to obtain subgrid statistics relevant to Large Eddy Simulation (LES) engineering modeling. The DNS employs a real gas state equation, detailed chemistry, accurate property models, multicomponent, differential, and cross diffusion. The parallel simulations were conducted using eighth order central finite differencing in conjunction with a fourth order accurate Runge-Kutta time integration, on resolutions up to 135 million grid points, and used up to 2,016 processing cores. All simulations are for an ambient pressure of 100 atm and are relevant to rocket engine conditions. The particular focus of the study is on analyzing the subgrid heat flux vector which has thus far been nearly universally ignored in the literature. DNS provides a near \u27exact\u27 description of all of the scales of the flow. For this study the DNS database is filtered over a range of filter widths to provide the exact LES governing equations; including those terms requiring modeling. The filtered heat flux vector is extensively compared with the heat flux vector calculated as a function of the filtered primitive variables (ie. the exact LES term is compared with its form available within an actual LES). The difference between these forms defines the subgrid heat flux vector. The subgrid heat flux vector is found to be insignificant for pure mixing cases, however, even for mixing cases the divergence of the subgrid heat flux vector is of the same order as the actual heat flux vector, other subgrid terms in the LES energy equation. Both the subgrid heat flux vector and its divergence are found to be substantially larger in reacting flows due to the associated large temperature gradients. The analysis is done both globally across the entire flame, as well as by conditionally averaging over specific regions of the flame; including regions of large subgrid kinetic energy, subgrid scalar dissipation, subgrid temperature variance, flame temperature, etc. These results highlight specific regions of the flame where modeling errors may occur in an actual LES if the subgrid heat flux vector is neglected. The dynamic/similarity modeling approach is therefore derived and tested for use in modeling the subgrid heat flux vector. An analysis of the model performance indicates that although the model improves the prediction of the filtered heat flux vector in both mixing and reacting flows, it nevertheless requires improvement. In particular, the model performance deteriorates with increasing filter width, and retains substantial errors when the divergence of the heat flux vector is considered. However, the model shows improved results for the higher Reynolds number simulation

On the effectiveness and limitations of captioning in L2 listening

Listening is often perceived to be the most challenging skill by second/foreign language (L2) learners. Due to its real-time nature, L2 listeners experience several comprehension problems related to the processing of aural input. To scaffold L2 listening, captioning is commonly used since the dual coding of aural and written stimuli is expected to make L2 input more comprehensible leading to more in-depth processing. However, a survey of the extant literature precludes us from drawing firm conclusions about the effectiveness of captioning since in some circumstances captions were found to have no significant effect on listening comprehension. So, the question of whether captions function as a comprehension aid in L2 listening remains inconclusive. Hence, adopting a narrative literature review methodology, the present study aims to contribute to this inconsistent research area by clarifying some of these issues answering the following questions: (1) Is captioning really effective in L2 listening?, (2) Does captioning always work for L2 listening?, and (3) Why is research on captioning in L2 listening still inconclusive?  Based on the insights gained, it is concluded that the mere presence of captions does not necessarily lead to improved comprehension. Captioning effectiveness is influenced by learner, material, measurement, task, and L1/L2 characteristics. Implications arising are discussed

BRIDGING IN-CLASS AND OUT-OF-CLASS LEARNING THROUGH PODCAST-INTERTWINED COLLABORATIVE TASKS TO REDUCE EFL SPEAKING ANXIETY AMONG HIGHER PROFICIENCY LEARNERS

Although speaking anxiety among foreign language learners at lower levels of proficiency has been extensively studied, far too little attention has been paid to learners at more advanced levels like student teachers enrolled in English Language Teaching (ELT) programs. However, speaking in the target language is a complicated mental process influenced by several other factors than proficiency. The present study has aptly been undertaken due to considerable reticence on the part of student teachers in communicative activities. An action plan was initiated to identify the sources of student teachers’ avoidance behaviors in oral production and address the concerns generated by these factors. An open-ended survey, journals, overall reflection papers and field notes were employed to gain insights as to the research process. Analysis of qualitative data revealed that student teachers were susceptible to experiencing anxiety in oral production due to personal and interpersonal issues, and they were positive in their perceptions of the planned intervention since it helped them build a sense of community in their classroom and enhance their self-esteem. These findings suggest several courses of action for language practitioners and teacher training institutions. Keywords: speaking anxiety; student teachers; collaborative learning; podcasts; out-of-class learnin

Adaptation Problems And Attitudes Of Teachers Towards Technological Material Using In Courses

AbstractWith digital boards student can interact with claver course contents, teachers can save the board picture. It can be thought that digital boards are so efficient and useful. However, the main point is adaptation capabilities of existing teachers. Considering the capabilities of teachers on technological materials, it is difficult to achieve targeted success. So before building technological infrastructure to every classroom, it is important to make knowledge about these technologies. Because it is more important how you can benefit from technology than what it can be do. As a result in-service training is very important about using new technologies for existing teachers before facing with that. The sample of this study comprised of 50 participants who are high school and primary school teachers. The data were collected through a questionnair

Unusual presentation of multiple nerve entrapment: a case report

Cubital tunnel syndrome is the most common form of ulnar nerve entrapment and the second most common entrapment neuropathy of the upper extremity after carpal tunnel syndrome. However, bilateral compressive ulnar neuropathy is a rare condition. Electro diagnostic studies are a valid and reliable means of confirming the diagnosis

Meme kanseri cerrahisi sonrası lenfödemi olan ve olmayan kadınlarda skapula ve üst ekstremite fonksiyonları ve yaşam kalitesinin karşılaştırılması

xviii, 114 sayfa29 cm. 1 CDÖZETGiriş-Amaç: Meme kanseri Türkiye'de ve tüm dünyada kadınlarda en sık görülen kanser türüdür. Meme kanseri tedavisinin en önemli komplikasyonlarından biri lenfödemdir. Çalışmanın amacı meme kanseri cerrahisi sonrası lenfödemli kadınlarda skapula ve üst ekstremite fonksiyonlarını ve yaşam kalitesini araştırmak, lenfödemsiz kadınlarla karşılaştırmak ve bu parametreler ile ödem şiddeti arasındaki ilişkiyi belirlemekti. Materyal-Metod: Çalışmaya tek taraflı meme kanseri teşhisiyle cerrahi geçirmiş lenfödem gelişen 50 kadın olgu (yaş54,34 9,08 yıl, Beden Kütle İndeksi (BKİ) 30,10 4,03 kg/cm² ve gelişmeyen 57 kadın olgu (yaş53,68 9,41 yıl, BKİ 29,0 5,44 kg/cm²) dâhil edildi.ABSTRACTIntroduction-Aim: Breast cancer is the most common cancer in women in Turkey and all over the world. One of the most important complications of breast surgery is lymphedema. The aim of the study was to determine the scapula and upper extremity functions and quality of life in women with lymphedema after breast cancer surgery, to compare with women without lymphedema and to search the relationship between these parameters and edema severity. Materials and methods: Fifty women with lymphedema (age54,34 9,08 years, Body Mass Index (BMI)30,10 4,03 kg/cm²) and fifty-seven women without lymphedema (age53,68 9,41 years, BMI 29,0 5,44 kg/cm²) after unilaterally surgery for breast cancer were included in the stud

Feasibility Analysis of Solar Wall Application in Seed Maize Drying

Nowadays the energy issue in agricultural production is being aggravated. One of the most energy-intensive production stages is drying. Many companies are looking towards highly efficient heating solutions which can be applied with established renewable technologies instead of fossil fuels. One of the basic problems in seed maize drying firm is the reduction of energy demand for hot air supply to drying room heating. In this study, in order to use the LPG for seed maize drying, the possibilities of using solar wall application were examined. The results show that hot air supply with this method is applicable. It is estimated that daytime drying energy savings varies between 33.8- 82.2% in August, 27.7-67.2% in September

Nanomaterials Based Drinking Water Purification: Comparative Study with a Conventional Water Purification Process

One of the ways of fully securing the presence of fresh water is water treatment process. Nanomaterials and nanotechnology offers an innovative solution for water treatment. In this study, physical, chemical and microbiological improvement rates of raw water were analyzed after filtration with graphene oxide. Graphene oxide's water treatment performance; silver nanoparticles, silver nanoparticles & graphene oxide composites that are commonly used in water treatment were compared with a traditional treatment method. When compared to the traditional method, there were improvements of 50 %, 40.7 %, 86.8 % and 45.5 % for color, TIC, TOC and hardness properties, respectively in water treatment by GO-based filtration with solid liquid ratio of 0.7 % (v/v). In water treatment with GO-Ag based filtration, 39.8 %, 69.8 %, 10.3 % and 28.6 % of improvements were obtained for TIC, TOC, hardness and LSI value compared to the conventional method. Both GO at 0.7 % (v/v) solid-liquid ratio and GO-Ag nanocomposites were successful in the number of total viable microorganisms and inhibiting microorganisms such as Escherichia coli fecal (gaita-infected), Salmonella typhi, Enterococcus faecalis, Pseudomona aeruginosa and Staphylococcus aureus. Among the studied parameters GO-Ag nanocomposites found to be the most suitable for drinking water treatment