An embedded boundary approach for simulation of reacting flow problems in complex geometries with moving and stationary boundaries

Many useful engineering devices involve moving boundaries interacting with a reacting compressible flow. Examples of such applications include propulsion systems with moving components such as Internal Combustion (IC) engines, hypersonic propulsive devices such as Oblique Detonation Wave (ODW) engines and solid rocket motors involving regressing propellant surfaces. Computational Fluid Dynamics (CFD) can be effectively employed to study these systems. However, conventional numerical methods face several difficulties related to grid generation, treatment of moving boundaries, lack of adequate grid resolution at an affordable computational cost, and shortcomings in closure models required for Large Eddy Simulation (LES). This thesis demonstrates new accurate numerical models and subgrid closures for LES of problems in non-trivial geometries with moving boundaries. A new high-order adaptive cut-cell based embedded boundary method is developed for viscous flows, which can provide a smooth and accurate reconstruction to predict the near-wall shear stress and pressure distribution. The method can achieve a high order of accuracy even under adverse geometrical constraints such as narrow gaps and sharp corners due to a novel and robust cell clustering algorithm. This algorithm also enforces the stability of the numerical scheme in the presence of arbitrary low volume cells formed in the cell cutting process. Additionally, an extended cell clustering approach, which can achieve exact conservation of mass, momentum, and energy is proposed for moving boundaries. The embedded boundary method is built on a massively parallel framework that performs block structured Adaptive Mesh Refinement (AMR) by interfacing with the BoxLib open source library. This modeling framework is then applied to study fundamental physics in high-speed propulsion systems, for example, shock-turbulence interactions, flame-turbulence interaction, and flame/detonation stabilization in a reacting system. LES using the multilevel subgrid closure for flow and chemistry is used to study flame anchoring in a transverse reacting jet in cross flow. Important mechanisms that stabilize the flame are identified and shown to be consistent with past observations from experiments and using direct numerical simulations (DNS) but obtained here using much coarser grid LES. Finally, to demonstrate the ability of the methodology to simulate moving bodies in a reactive system, DNS of a hypersonic projectile fired into a reacting flow is performed to reveal key effects of pressure on the stabilization of detonation ahead of the projectile.Ph.D

Result Prediction Using K-Nearest Neighbor Algorithm For Student Performance Improvement

Abstract—The examination results have become an integral part of every student’s life. The educational institution’s ranking is greatly influenced by the university results. This paper mainly focuses on the prediction of a student’s university result by making use of different attributes. These attributes might be of quantitative and qualitative type. The quantitative attributes used are Internal Assessments, Attendance percentage, Number of On-Duties taken and Overall Assignments completed. The qualitative attributes include Subject feedback, Faculty feedback, and whether the student is a Day Scholar/Hosteller. Here, we make use of k-Nearest Neighbor algorithm (or k-NN for short) against the historical data of students for more accurate prediction of results. In this method all the attributes considered are converted to the same scale. This algorithm makes use of the Euclidean distance formula which is used to find the nearest record. This algorithm predicts better results which help students maximize their academic output

LHX2 Interacts with the NuRD Complex and Regulates Cortical Neuron Subtype Determinants Fezf2 and Sox11

In the developing cerebral cortex, sequential transcriptional programs take neuroepithelial cells from proliferating progenitors to differentiated neurons with unique molecular identities. The regulatory changes that occur in the chromatin of the progenitors are not well understood. During deep layer neurogenesis, we show that transcription factor LHX2 binds to distal regulatory elements of Fezf2 and Sox11, critical determinants of neuron subtype identity in the mouse neocortex. We demonstrate that LHX2 binds to the nucleosome remodeling and histone deacetylase histone remodeling complex subunits LSD1, HDAC2, and RBBP4, which are proximal regulators of the epigenetic state of chromatin. When LHX2 is absent, active histone marks at the Fezf2 and Sox11 loci are increased. Loss of LHX2 produces an increase, and overexpression of LHX2 causes a decrease, in layer 5 Fezf2 and CTIP2-expressing neurons. Our results provide mechanistic insight into how LHX2 acts as a necessary and sufficient regulator of genes that control cortical neuronal subtype identity

Hybrid solution-adaptive unstructured Cartesian method for large-eddy simulation of detonation in multi-phase turbulent reactive mixtures

Issued as final reportA class of problems of both great fundamental interest and practical relevance is in the field of highly compressible turbulent flows of multi-fluids. Shock interaction with turbulence and/or flames have many practical applications and require advanced computational techniques. This report summarizes the work done to date to develop methods and algorithms for hybrid structured-unstructured methods in large-eddy simulations (LES). Particular emphasis is given to efficiency and accuracy while using techniques applicable to solution-adaptive approaches. The formulation and algorithm for statically refined grids for DNS and LES is shown to be robust and allows rapid inclusion in existing solvers with a minimal change in code base while also ensuring compatibility with existing features. Extensions to solution-adaptive techniques from the static approach are discussed. The application of the method to numerous flow examples demonstrates the capability and robustness of the method. Finally, an adaptive Cartesian method using level-sets and cut-cells to solve the interactions of complex, deforming and reacting bodies in a compressible flow field is developed and validated.United States. Air Force. Office of Scientific Researc

Isolated Systolic Blood Pressure and Red-Complex Bacteria—A Risk for Generalized Periodontitis and Chronic Kidney Disease

Hypertension is a risk factor for generalized periodontitis (GP) and chronic kidney diseases (CKD). However, the role of isolated systolic blood pressure as one of the major risks for these inflammatory diseases has not been explored. Very limited studies exist identifying the red-complex bacteria in association with the isolated systolic blood pressure. Hence, the main objective of this study was to assess the isolated systolic blood pressure and the red-complex bacteria along with the demographic variables, periodontal parameters, and renal parameters in patients with generalized periodontitis and chronic kidney disease. One hundred twenty participants (age 30–70 years) were divided into four groups—Group C: control (systemically and periodontally healthy subjects), Group GP: generalized periodontitis, Group CKD: subjects with CKD with good periodontal health, Group CKD + GP: subjects with both generalized periodontitis and CKD. Demographic variables and periodontal parameters were measured and recorded. Blood pressure measurements and a detailed history and renal parameters such as serum creatinine, eGFR, and fasting blood sugar were recorded. The red-complex bacteria (RCB) were assessed in the subgingival plaque samples of all four groups using RT-PCR. Older participants (above 50 years) showed worse periodontal scores in the CKD + GP group along with elevated isolated systolic blood pressure, higher serum creatinine, and fasting blood sugar. eGFR was significantly decreased compared to the other groups. Bacterial counts were higher in the GP + CKD group, suggesting that they may be at a higher risk for generalized periodontitis and chronic kidney disease. Isolated systolic blood pressure (ISBP) and RCB were significantly correlated with the renal and periodontal parameters. A log-linear relationship exists between periodontal disease, CKD, RCB, and isolated systolic hypertension levels

Red-Complex Bacterial Levels in Pregnant Women With Preeclampsia and Chronic Periodontitis

ABSTRACT: Objectives: The presence of red-complex bacteria (RCB) has been associated with the occurrence of not only periodontal disease but also other systemic diseases, thereby potentiating an oral–systemic relationship. This study aimed to explore the levels of periodontal RCB in pregnant preeclamptic women with periodontal disease, potentiating the pathophysiology of a bacterial association in both periodontitis and preeclampsia. Methods: Six hundred pregnant women (aged 20 to 35 years) in their third trimester were selected and divided into 3 groups comprising a control group (systemically and periodontally healthy pregnant women), group A (preeclamptic women with chronic periodontitis), and group B (preeclamptic women without chronic periodontitis). Demographic variables and periodontal parameters were recorded. Other variables such as systolic blood pressure (SBP) and diastolic blood pressure (DBP) and the urine protein content were also estimated. RCB, namely Porphyromonas gingivalis (Pg), Treponema denticola (Td), and Tenerella forsythia (Tf), were assessed in both subgingival plaque samples and placental samples of all the pregnant participants in the study. Results: The mean weight, mean body mass index, mean SBP, mean DBP, and mean urine protein content were significantly elevated in group A and group B when compared to the control group. Preeclamptic women with chronic periodontitis (group A) had higher levels of plaque index, probing pocket depth, bleeding on probing, and clinical attachment level as compared with the other groups. The numbers of the RCB were found to be elevated in group A, out of which Pg was found to be more prevalent. Conclusions: Our findings indicate that the periodontal indices, blood pressure, and urine protein content were found to be higher in preeclamptic women with periodontitis. Hence, reducing the periodontal bacterial load in pregnant women via good oral hygiene maintenance would further reduce the putative risk of adverse pregnancy outcomes including preeclampsia in these women

Discovering putative prion-like proteins in plasmodium falciparum: a computational and experimental analysis

Prions are a singular subset of proteins able to switch between a soluble conformation and a self-perpetuating amyloid state. Traditionally associated with neurodegenerative diseases, increasing evidence indicates that organisms exploit prion-like mechanisms for beneficial purposes. The ability to transit between conformations is encoded in the so-called prion domains, long disordered regions usually enriched in glutamine/asparagine residues. Interestingly, Plasmodium falciparum, the parasite that causes the most virulent form of malaria, is exceptionally rich in proteins bearing long Q/N-rich sequence stretches, accounting for roughly 30% of the proteome. This biased composition suggests that these protein regions might correspond to prion-like domains (PrLDs) and potentially form amyloid assemblies. To investigate this possibility, we performed a stringent computational survey for Q/N-rich PrLDs on P. falciparum. Our data indicate that ∼10% of P. falciparum protein sequences have prionic signatures, and that this subproteome is enriched in regulatory proteins, such as transcription factors and RNA-binding proteins. Furthermore, we experimentally demonstrate for several of the identified PrLDs that, despite their disordered nature, they contain inner short sequences able to spontaneously self-assemble into amyloid-like structures. Although the ability of these sequences to nucleate the conformational conversion of the respective full-length proteins should still be demonstrated, our analysis suggests that, as previously described for other organisms, prion-like proteins might also play a functional role in P. falciparum.This work was funded by grants BIO2016-78310-R to SV and BIO2014-52872-R to XF-B (Ministerio de Economía y Competitividad, Spain), which included FEDER funds, and by ICREA, ICREA ACADEMIA 2015 to SV. ISGlobal and IBEC are members of the CERCA Program, Generalitat de Catalunya