Noise characteristics of passive components for phased array applications

The results of a comparative study on noise characteristics of basic power combining/dividing and phase shifting schemes are presented. The theoretical basics of thermal noise in a passive linear multiport are discussed. A new formalism is presented to describe the noise behavior of the passive circuits, and it is shown that the fundamental results are conveniently achieved using this description. The results of analyses concerning the noise behavior of basic power combining/dividing structures (the Wilkinson combiner, 90 deg hybrid coupler, hybrid ring coupler, and the Lange coupler) are presented. Three types of PIN-diode switch phase shifters are analyzed in terms of noise performance

Fonksiyonel Kademelendirilmiş Plakalar ile Desteklenmiş Bal Peteği Sandviç Yapıların Düşük Hızlı Darbe Davranışlarının İncelenme

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2015Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2015Sandviç yapılar, sahip oldukları yüksek performans özelliklerinin farklı malzeme kombinasyonları ile elde edildiği kompozit malzeme alanının özel bir uygulamasıdır. Konvansiyonel malzemelere göre sahip oldukları birçok üstün özellikleri ile oldukça geniş bir uygulama alanına (havacılık ve uzay, otomotiv, savunma, vs.) sahiptirler. Sandviç yapı elemanları, uygulama alanına yönelik istenilen özelliklere sahip olması açısından farklı yüzey plakaları ve çekirdek malzemelerinden oluşabilir. Sandviç yapılar, kullanım alanlarına bağlı olarak darbeli yüklemelere maruz kalabildikleri için düşük hızlı darbe cevabının belirlenmesi oldukça önemli bir rol oynamaktadır. Fonksiyonel kademelendirilmiş plakalar ile desteklenmiş bal peteği sandviç yapıların düşük hızlı darbe yükleri altındaki deformasyonları ve enerji sönümleme kabiliyetleri LS-DYNA® sonlu elemanlar programı kullanılarak araştırılmıştır. Sandviç yapı, Al/SiC fonksiyonel kademelendirilmiş kompozit yüzey plakaları ve Al 3003-H19 alaşımı bal peteğinden oluşmaktadır. Sandviç yapının darbe cevabı, fonksiyonel kademelendirilmiş destek plakalarının farklı malzeme kompozisyonu, vurucu kütlesinin sabit olduğu farklı çarpma enerjileri ve bal peteği çekirdek malzemesinin farklı hücre duvar kalınlıkları için incelenmiştir.Sandwich structures are specific applications of the composite materials whose high performance properties are obtained by different material combinations. They have quite extensive usage areas (aeronautics and aerospace, automotive, defense, etc.) with their several high quality properties compared with the conventional materials. Sandwich structures can be consisted of different facesheets and core materials in order to have required properties for the application areas. The determination of the low-velocity impact response of the sandwich structures has an important role by reason of their working areas with impulsive loadings. The deformations and energy absorption capability of the honeycomb sandwich structures reinforced by the functionally graded plates under low-velocity impact loads were investigated using explicit finite element software, LS-DYNA®. The sandwich structure was consisted of Al/SiC FG facesheets and Al 3003-H19 aluminum honeycomb core. The impact response of the sandwich structure was investigated in terms of different material compositions of the FG plates, impact energies and cell wall thickness of the honeycomb core

High multiplicity processes at NLO with BlackHat and Sherpa

In this contribution we review recent progress with fixed-order QCD predictions for the production of a vector boson in association with jets at hadron colliders, using the programs BlackHat and SHERPA. We review general features of next-to-leading-order (NLO) predictions for the production of a massive vector boson in association with four jets. We also discuss how precise descriptions of vector-boson production can be applied to the determination of backgrounds to new physics signals. Here we focus on data-driven backgrounds to a missing-energy-plus-jets search performed by CMS. Finally, we review recent progress in developing theoretical tools for high-multiplicity loop-computation within the BlackHat-library. In particular, we discuss methods for handling the color degrees of freedom in multi-jet predictions at NLO.Comment: 12 pages, contribution to the proceedings of Loops and Legs 201

Emerging Roles and Landscape of Translating mRNAs in Plants

Plants use a wide range of mechanisms to adapt to different environmental stresses. One of the earliest responses displayed under stress is rapid alterations in stress responsive gene expression that has been extensively analyzed through expression profiling such as microarrays and RNA-sequencing. Recently, expression profiling has been complemented with proteome analyses to establish a link between transcriptional and the corresponding translational changes. However, proteome profiling approaches have their own technical limitations. More recently, ribosome-associated mRNA profiling has emerged as an alternative and a robust way of identifying translating mRNAs, which are a set of mRNAs associated with ribosomes and more likely to contribute to proteome abundance. In this article, we briefly review recent studies that examined the processes affecting the abundance of translating mRNAs, their regulation during plant development and tolerance to stress conditions and plant factors affecting the selection of translating mRNA pools. This review also highlights recent findings revealing differential roles of alternatively spliced mRNAs and their translational control during stress adaptation. Overall, better understanding of processes involved in the regulation of translating mRNAs has obvious implications for improvement of stress tolerance in plants.Peer reviewe

On the arithmetic sums of Cantor sets

Let C_\la and C_\ga be two affine Cantor sets in $\mathbb{R}$ with similarity dimensions d_\la and d_\ga, respectively. We define an analog of the Bandt-Graf condition for self-similar systems and use it to give necessary and sufficient conditions for having \Ha^{d_\la+d_\ga}(C_\la + C_\ga)>0 where C_\la + C_\ga denotes the arithmetic sum of the sets. We use this result to analyze the orthogonal projection properties of sets of the form C_\la \times C_\ga. We prove that for Lebesgue almost all directions $\theta$ for which the projection is not one-to-one, the projection has zero (d_\la + d_\ga)-dimensional Hausdorff measure. We demonstrate the results on the case when C_\la and C_\ga are the middle-(1-2\la) and middle-(1-2\ga) sets

Myanmar Ecological Forecasting: Utilizing NASA Earth Observations to Monitor, Map, and Analyze Mangrove Forests in Myanmar for Enhanced Conservation

Mangroves supply many essential environmental amenities, such as preventing soil erosion, filtering water pollution, and protecting shorelines from harmful waves, floods, storms and winds. The Mangroves in Myanmar not only provide citizens with a food source, but they also offer firewood, charcoal, and construction materials. The depletion of mangroves is threatening more than the biodiversity however; Myanmar's fiscal livelihood is also in harm's way. Mangroves are valued at $100,000 to$277,000 per square kilometer and if managed in a sustainable fashion, can infuse constant income to the emerging Myanmarese economy. This study analyzed three coastline regions, the Ayeyarwady Delta, Rakhine and Tanintharyi, and mapped the spatial extent of mangrove forest during the dry season in 2000 and 2013. The classifications were derived from Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and Landsat 8 Operation Land Imager (OLI) imagery, as well as the Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) digital elevation model information. This data was atmospherically corrected, mosaicked, masked and classified in ENVI, followed by ArcGIS to perform raster calculations and create final products. Forest degradation collected from 2000 to 2013 was later used to forecast the density and health of Mangroves in the year 2030. These results were subsequently presented to project partners Dr. Peter Leimgruber and Ellen Aiken at the Smithsonian Conservation Biology Institute in Front Royal, VA. After the presentation of the project to the partners, these organizations formally passed on to the Myanmar Ministry of Environment, Conservation and Forestry for policy makers and forest managers to utilize in order to protect the Myanmar mangrove ecosystem while sustaining a healthy economy

Severe NDE1-mediated microcephaly results from neural progenitor cell cycle arrests at multiple specific stages

Microcephaly is a cortical malformation disorder characterized by an abnormally small brain. Recent studies have revealed severe cases of microcephaly resulting from human mutations in the NDE1 gene, which is involved in the regulation of cytoplasmic dynein. Here using in utero electroporation of NDE1 short hairpin RNA (shRNA) in embryonic rat brains, we observe cell cycle arrest of proliferating neural progenitors at three distinct stages: during apical interkinetic nuclear migration, at the G2-to-M transition and in regulation of primary cilia at the G1-to-S transition. RNAi against the NDE1 paralogue NDEL1 has no such effects. However, NDEL1 overexpression can functionally compensate for NDE1, except at the G2-to-M transition, revealing a unique NDE1 role. In contrast, NDE1 and NDEL1 RNAi have comparable effects on postmitotic neuronal migration. These results reveal that the severity of NDE1-associated microcephaly results not from defects in mitosis, but rather the inability of neural progenitors to ever reach this stage

Fonksiyonel Kademelendirilmiş Sandviç Plakaların Balistik Darbe Yükü Altındaki Davranışı Üzerinde Farklı Seramik Bileşenlerinin

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2015Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2015Günümüzde de gelişen tehditler karşısında daha etkin balistik koruma sağlayacak hafif ve yüksek performanslı zırhların geliştirilmesi kritik bir ihtiyaç haline gelmiş ve bu sahadaki yeni malzeme arayışları seramik ön yüzlü kompozit zırhları ön plana çıkarmıştır. Katmanlı yapıya sahip bu plakalar yüksek mukavemetleri ve yüksek rijitlikleri nedeniyle balistik sistemlerde yaygın olarak kullanılırlar. Ancak, katmanlardaki malzeme özelliklerinin ani olarak değişmesi nedeniyle ara yüzeylerde yüksek gerilmeler meydana gelir ve bu gerilmeler de katmanlar arasında ayrılmalara (delaminasyon) neden olur. Bu olumsuz etkiler fonksiyonel kademelendirilmiş malzemeler (FGM) kullanılarak azaltılabilir ya da ortadan kaldırılabilir. Bu çalışma ile farklı seramik bileşenlere sahip fonksiyonel kademelendirilmiş sandviç plakalarda balistik darbe yükleme altında meydana gelen hasar mekanizmaları ve deformasyonları deneysel olarak incelenmiştir.Today, the development of high-performance and light armors has become a critical requirement against emerging threats. The research for new materials in this field has brought ceramic-faced composite armors to the forefront. Layered composite structures are widely used in ballistic systems due to their high strength and high stiffness. An abrupt change in their material properties across an interface between discrete materials introduces large interlaminar stresses that could cause delamination. One way to overcome this adverse effect is to use a functionally graded material (FGM). The purpose of this study is to determine damage and deformation mechanisms of functionally graded sandwich plates, which have different ceramic components, under ballistic impact loads