Computational aspects of zonal algorithms for solving the compressible Navier-Stokes equations in three dimensions

Transonic flow fields about wing geometries are computed using an Euler/Navier-Stokes approach in which the flow field is divided into several zones. The flow field immediately adjacent to the wing surface is resolved with fine grid zones and solved using a Navier-Stokes algorithm. Flow field regions removed from the wing are resolved with less finely clustered grid zones and are solved with an Euler algorithm. Computational issues associated with this zonal approach, including data base management aspects, are discussed. Solutions are obtained that are in good agreement with experiment, including cases with significant wind tunnel wall effects. Additional cases with significant shock induced separation on the upper wing surface are also presented

Characterization of an embedded RF-MEMS switch

An RF-MEMS capacitive switch for mm-wave integrated circuits, embedded in the BEOL of 0.25μm BiCMOS process, has been characterized. First, a mechanical model based on Finite-Element-Method (FEM) was developed by taking the residual stress of the thin film membrane into account. The pull-in voltage and the capacitance values obtained with the mechanical model agree very well with the measured values. Moreover, S-parameters were extracted using Electromagnetic (EM) solver. The data observed in this way also agree well with the experimental ones measured up to 110GHz. The developed RF model was applied to a transmit/receive (T/R) antenna switch design. The results proved the feasibility of using the FEM model in circuit simulations for the development of RF-MEMS switch embedded, single-chip multi-band RF ICs

Two-element antenna-active phase shifter packaging at 77 GHz

This work presents a low cost and wire-bonded active phase shifter chip to RF circuitry on PCB board packaging for implementing a two-element phased array antenna at 77 GHz. The 1.5 mm and times; 1.1 mm chip is embedded in RO3003 PCB board and its GSG ports are wire-bonded to CPW lines that are expanded to feed the patch antenna on the PCB board. A low loss CPW to microstrip line transition is designed to exploit and transmit the signal from the GSG pads on the chip to the microstrip line on the PCB. The beam of the two-element array can be steered between and plusmn;20 and deg; by controlling the DC bias voltage of the active phase shifter chip

Okul Öncesı Öğretmenlerinin Etkinlik Planı Hazırlama Becerilerinin İncelenmesi: Uyarlama, Aile Katılımı ve Değerlendirme

DergiPark: 700610tredBu çalışmanın amacı okul öncesi öğretmenlerinin kendilerine verilen kazanım ve göstergeler ile öğrenme süreci doğrultusunda uyarlama, aile katılımı ve değerlendirme boyutlarını planlama becerilerini incelemektir. Araştırma nitel araştırma yöntemlerinden durum çalışması deseninde yürütülmüştür ve çalışmada doküman incelemesi yapılmıştır. Araştırmanın çalışma grubunu Milli Eğitim Bakanlığı tarafından yürütülen “Öğretmenlerimizle 2023’e Projesi” pilot uygulaması kapsamında 13 farklı ilden eğitici eğitimine katılan 53 okul öncesi öğretmeni oluşturmaktadır. Dokümanları oluşturmak üzere katılımcılara etkinlik planı formatı verilmiş ve eş zamanlı olarak herhangi bir kaynağa ulaşmadan kendilerinden istenen bölümleri planlamaları beklenmiştir. Çalışmanın verileri içerik analizi yoluyla analiz edilmiştir. Araştırmanın sonucunda öğretmenlerin uyarlama planlarken çoğunlukla fiziksel destek sağlama, basit yönergeler verme gibi yöntem ve tekniklere başvurdukları görülürken; aile katılımı planlarken daha fazla çeşitliliğe yöneldikleri belirlenmiştir. Öğretmenlerin değerlendirme planlarken ise çoğunlukla değerlendirme sorularını kullandıkları tespit edilmiştir. Sonuç olarak öğretmenlerin uyarlama ve aile katılımı planlama becerilerinin değerlendirme planlama becerilerine görece daha iyi olduğu; ancak tüm alanlarda desteklenmeye ihtiyaçlarının bulunduğu saptanmıştır

Non-conformal Hydrodynamics in Einstein-dilaton Theory

In the Einestein-dilaton theory with a Liouville potential parameterized by $\eta$, we find a Schwarzschild-type black hole solution. This black hole solution, whose asymptotic geometry is described by the warped metric, is thermodynamically stable only for $0 \le \eta < 2$. Applying the gauge/gravity duality, we find that the dual gauge theory represents a non-conformal thermal system with the equation of state depending on $\eta$. After turning on the bulk vector fluctuations with and without a dilaton coupling, we calculate the charge diffusion constant, which indicates that the life time of the quasi normal mode decreases with $\eta$. Interestingly, the vector fluctuation with the dilaton coupling shows that the DC conductivity increases with temperature, a feature commonly found in electrolytes.Comment: 27 pages and 2 figures, published in JHE

Point Interaction in two and three dimensional Riemannian Manifolds

We present a non-perturbative renormalization of the bound state problem of n bosons interacting with finitely many Dirac delta interactions on two and three dimensional Riemannian manifolds using the heat kernel. We formulate the problem in terms of a new operator called the principal or characteristic operator. In order to investigate the problem in more detail, we then restrict the problem to one particle sector. The lower bound of the ground state energy is found for general class of manifolds, e.g., for compact and Cartan-Hadamard manifolds. The estimate of the bound state energies in the tunneling regime is calculated by perturbation theory. Non-degeneracy and uniqueness of the ground state is proven by Perron-Frobenius theorem. Moreover, the pointwise bounds on the wave function is given and all these results are consistent with the one given in standard quantum mechanics. Renormalization procedure does not lead to any radical change in these cases. Finally, renormalization group equations are derived and the beta-function is exactly calculated. This work is a natural continuation of our previous work based on a novel approach to the renormalization of point interactions, developed by S. G. Rajeev.Comment: 43 page

Isometric Embeddings and Noncommutative Branes in Homogeneous Gravitational Waves

We characterize the worldvolume theories on symmetric D-branes in a six-dimensional Cahen-Wallach pp-wave supported by a constant Neveu-Schwarz three-form flux. We find a class of flat noncommutative euclidean D3-branes analogous to branes in a constant magnetic field, as well as curved noncommutative lorentzian D3-branes analogous to branes in an electric background. In the former case the noncommutative field theory on the branes is constructed from first principles, related to dynamics of fuzzy spheres in the worldvolumes, and used to analyse the flat space limits of the string theory. The worldvolume theories on all other symmetric branes in the background are local field theories. The physical origins of all these theories are described through the interplay between isometric embeddings of branes in the spacetime and the Penrose-Gueven limit of AdS3 x S3 with Neveu-Schwarz three-form flux. The noncommutative field theory of a non-symmetric spacetime-filling D-brane is also constructed, giving a spatially varying but time-independent noncommutativity analogous to that of the Dolan-Nappi model.Comment: 52 pages; v2: References adde

Combined oral triglyceride and glucose tolerance test after acute ischemic stroke to predict recurrent vascular events: the Berlin "Cream&Sugar" study

Background: Elevated triglyceride and glucose levels are associated with an increased cardiovascular disease risk including ischemic stroke. It is not known whether the response to a combined oral triglyceride and glucose challenge after ischemic stroke improves identification of patients with increased risk for recurrent vascular events. Methods: The prospective, observational Berlin "Cream&Sugar" study was conducted at 3 different university hospital sites of the Charite-Universitatsmedizin Berlin, Germany, between January 24, 2009 and July 31, 2017. Patients with first-ever ischemic stroke were recruited 3 to 7 days after stroke. An oral triglyceride tolerance test (OTTT) and consecutive blood tests before (t(0)) as well as 3 (t(1)), 4 (t(2)), and 5 hours (t(3)) after OTTT were performed in fasting patients. An oral glucose tolerance test was performed in all nondiabetic patients 3 hours after the start of OTTT. Outcomes of the study were recurrent fatal or nonfatal stroke as well as a composite vascular end point including stroke, transient ischemic attack, myocardial infarction, coronary revascularization, and cardiovascular death assessed 1 year after stroke. Cox regression models were used to estimate hazard ratios and corresponding 95% CIs between patients with high versus low levels of triglyceride and glucose levels. Results: Overall 755 patients were included; 523 patients completed OTTT and 1-year follow-up. Patients were largely minor strokes patients with a median National Institutes of Health Stroke Scale score of 1 (0-3). Comparing highest versus lowest quartiles of triglyceride levels, neither fasting (adjusted hazard ratio(t0), 1.24 [95% CI, 0.45-3.42]) nor postprandial triglyceride levels (adjusted hazard ratio(t3), 0.44 [95% CI, 0.16-1.25]) were associated with recurrent stroke. With regard to recurrent vascular events, results were similar for fasting triglycerides (adjusted hazard ratio(t0), 1.09 [95% CI, 0.49-2.43]), however, higher postprandial triglyceride levels were significantly associated with a lower risk for recurrent vascular events (adjusted hazard ratio(t3), 0.42 [95% CI, 0.18-0.95]). No associations were observed between fasting and post-oral glucose tolerance test blood glucose levels and recurrent vascular risk. All findings were irrespective of the diabetic status of patients. Conclusions: In this cohort of patients with first-ever, minor ischemic stroke, fasting triglyceride or glucose levels were not associated with recurrent stroke at one year after stroke. However, higher postprandial triglyceride levels were associated with a lower risk of recurrent vascular events which requires further validation in future studies. Overall, our results do not support the routine use of a combined OTTT/oral glucose tolerance test to improve risk prediction for recurrent stroke.Clinical epidemiolog