Numerical investigation of high-pressure combustion in rocket engines using Flamelet/Progress-variable models

The present paper deals with the numerical study of high pressure LOx/H2 or LOx/hydrocarbon combustion for propulsion systems. The present research effort is driven by the continued interest in achieving low cost, reliable access to space and more recently, by the renewed interest in hypersonic transportation systems capable of reducing time-to-destination. Moreover, combustion at high pressure has been assumed as a key issue to achieve better propulsive performance and lower environmental impact, as long as the replacement of hydrogen with a hydrocarbon, to reduce the costs related to ground operations and increase flexibility. The current work provides a model for the numerical simulation of high- pressure turbulent combustion employing detailed chemistry description, embedded in a RANS equations solver with a Low Reynolds number k-omega turbulence model. The model used to study such a combustion phenomenon is an extension of the standard flamelet-progress-variable (FPV) turbulent combustion model combined with a Reynolds Averaged Navier-Stokes equation Solver (RANS). In the FPV model, all of the thermo-chemical quantities are evaluated by evolving the mixture fraction Z and a progress variable C. When using a turbulence model in conjunction with FPV model, a probability density function (PDF) is required to evaluate statistical averages of chemical quantities. The choice of such PDF must be a compromise between computational costs and accuracy level. State- of-the-art FPV models are built presuming the functional shape of the joint PDF of Z and C in order to evaluate Favre-averages of thermodynamic quantities. The model here proposed evaluates the most probable joint distribution of Z and C without any assumption on their behavior.Comment: presented at AIAA Scitech 201

Assessing Students' Answers to Open Questions

A number of Learning Management Systems (LMSs) exist on the market today. A subset of a LMS is the component in which student assessment is managed. In some forms of assessment, such as open questions, the LMS is incapable of evaluating the students’ responses and therefore human intervention is necessary. This study leverages the research conducted in recent studies in the area of Natural Language Processing, Information Extraction and Information Retrieval in order to provide a fair, timely and accurate assessment of student responses to open questions based on the semantic meaning of those responses. A component-based system utilizing a Text Pre-Processing phase and a Word/Synonym Matching phase has been developed to automate the open question assessment process. A small sample of student responses were tested against the system revealing areas in which the system could be improved.2010-1

The role of presumed probability density functions in the simulation of nonpremixed turbulent combustion

Flamelet-Progress-Variable (FPV) combustion models allow the evaluation of all thermochemical quantities in a reacting flow by computing only the mixture fraction Z and a progress variable C. When using such a method to predict turbulent combustion in conjunction with a turbulence model, a probability density function (PDF) is required to evaluate statistical averages (e.g., Favre averages) of chemical quantities. The choice of the PDF is a compromise between computational costs and accuracy level. The aim of this paper is to investigate the influence of the PDF choice and its modeling aspects to predict turbulent combustion. Three different models are considered: the standard one, based on the choice of a beta-distribution for Z and a Dirac-distribution for C; a model employing a beta-distribution for both Z and C; and the third model obtained using a beta-distribution for Z and the statistically most likely distribution (SMLD) for C. The standard model, although widely used, does not take into account the interaction between turbulence and chemical kinetics as well as the dependence of the progress variable not only on its mean but also on its variance. The SMLD approach establishes a systematic framework to incorporate informations from an arbitrary number of moments, thus providing an improvement over conventionally employed presumed PDF closure models. The rational behind the choice of the three PDFs is described in some details and the prediction capability of the corresponding models is tested vs. well-known test cases, namely, the Sandia flames, and H-2-air supersonic combustion

Corruption and bicameral reforms

During the last decade unicameral proposals have been put forward in fourteen US states. In this paper we analyze the effects of the proposed constitutional reforms, in a setting where decision making is subject to ‘hard time constraints’, and lawmakers face the opposing interests of a lobby and the electorate. We show that bicameralism might lead to a decline in the lawmakers’ bargaining power vis-a-vis the lobby, thus compromising their accountability to voters. Hence, bicameralism is not a panacea against the abuse of power by elected legislators and the proposed unicameral reforms could be effective in reducing corruption among elected representatives

Fungal Origins of the Bicyclo[2.2.2]diazaoctane Ring System of Prenylated Indole Alkaloids

Over eight different families of natural products, consisting of nearly seventy secondary metabolites, which contain the bicyclo[2.2.2]diazaoctane ring system, have been isolated from various Aspergillus, Penicillium, and Malbranchea species. Since 1968, these secondary metabolites have been the focus of numerous biogenetic, synthetic, taxonomic, and biological studies, and, as such, have made a lasting impact across multiple scientific disciplines. This review covers the isolation, biosynthesis, and biological activity of these unique secondary metabolites containing the bridging bicyclo[2.2.2]diazaoctane ring system. Furthermore, the diverse fungal origin of these natural products is closely examined and, in many cases, updated to reflect the currently accepted fungal taxonomy

Impact of industrial shelling and blanching on almond kernel integrity and color

Spanish almond industry expressed concerns over increasing kernel breakage during processing, particularly with the new almond cultivars introduced since 2005. This research aimed to (i) evaluate kernel breakage across different almond cultivars during shelling and blanching in Spanish industrial machines; (ii) identify the main factors contributing to breakage; and (iii) assess the impact of blanching on kernel color. Shelling breakage was lower in ‘Belona’ (2%) than ‘Guara’ (7%), potentially attributed to its higher water absorption and round shape. However, blanching, drastically increased breakage in ‘Belona’ (42%) compared to ‘Guara’ (29%). A large variability among cultivars (‘Carmel’ 12%, ‘Belona 2’ 32% significantly similar to ‘Guara’ 29%, and ‘Lauranne’ 43% significantly similar to ‘Belona’ 42%), was observed, but also between different batches of the same cultivar (‘Belona’ 42% and ‘Belona 2’ 32%), probably due to different growing conditions. ‘Lauranne’ and ‘Belona’ exhibited a higher tendency to produce halves, whereas ‘Guara’ produced more pieces. Kernel breakage during blanching was significantly correlated with kernel width (r = 0.57***), protein, (r = − 0.83***), and fat content (r = 0.67***). Blanching significantly affected kernel color (‘Carmel’, ‘Belona 2’, ‘Guara’, ‘Lauranne’, ‘Belona’; ΔE = 19, 14, 12, 11, 10, respectively) and was identified as a critical control point for breakage across the processing lineFunded by European Agricultural Fund for Rural Development (EAFRD) and “Departament d'Agricultura, Ramaderia, Pesca i Alimentació, Generalitat de Catalunya” through Operational Group “Operation 16.01.01 of Cooperation for Innovation of the Rural Development Program of Catalonia 2014–2020, QUALINUT project. Author Leontina Lipan has been funded by “Ministerio de Universidades” and the European-Union Next Generation EU within the frame of Grants for the Requalification of the Spanish University System, modality ‘Margarita Salas’. Pilot plant sample managing at IRTA was done by Magdalena Duran, Grant PTA 2022-022594-I funded by “Ministerio de Ciencia, Innovación y Universidades”/“Agencia Estatal de Investigación” (MICIU/AEI/10.13039/501100011033) and by European Social Fund Plus (ESF+). Authors knowledge “Almendras Martí” for housing the industrial experiments, samples supplying and personnel helping for the management of processing units.info:eu-repo/semantics/publishedVersio

Molecular and Functional Characterization of Three Different Postzygotic Mutations in PIK3CA-Related Overgrowth Spectrum (PROS) Patients: Effects on PI3K/AKT/mTOR Signaling and Sensitivity to PIK3 Inhibitors

BACKGROUND PIK3CA-related overgrowth spectrum (PROS) include a group of disorders that affect only the terminal portion of a limb, such as type I macrodactyly, and conditions like fibroadipose overgrowth (FAO), megalencephaly-capillary malformation (MCAP) syndrome, congenital lipomatous asymmetric overgrowth of the trunk, lymphatic, capillary, venous, and combined-type vascular malformations, epidermal nevi, skeletal and spinal anomalies (CLOVES) syndrome and Hemihyperplasia Multiple Lipomatosis (HHML). Heterozygous postzygotic PIK3CA mutations are frequently identified in these syndromes, while timing and tissue specificity of the mutational event are likely responsible for the extreme phenotypic variability observed. METHODS: We carried out a combination of Sanger sequencing and targeted deep sequencing of genes involved in the PI3K/AKT/mTOR pathway in three patients (1 MCAP and 2 FAO) to identify causative mutations, and performed immunoblot analyses to assay the phosphorylation status of AKT and P70S6K in affected dermal fibroblasts. In addition, we evaluated their ability to grow in the absence of serum and their response to the PI3K inhibitors wortmannin and LY294002 in vitro. RESULTS AND CONCLUSION: Our data indicate that patients' cells showed constitutive activation of the PI3K/Akt pathway. Of note, PI3K pharmacological blockade resulted in a significant reduction of the proliferation rate in culture, suggesting that inhibition of PI3K might prove beneficial in future therapies for PROS patients