Understanding large plastic deformation of SiC nanowires at room temperature

Tensile behaviors of SiC [111] nanowires with various possible microstructures have been investigated by molecular-dynamics simulations. The results show that the large plastic deformation in these nanowires is induced by the anti-parallel sliding of 3C grains along an ultra- thin intergranular amorphous film parallel to the (11¯1) plane and inclined at an angle of 19.47◦ with respect to the nanowire axis. The resulting large plastic deformation of SiC nanowires at room temperature is attributed to the stretching, breaking and re-forming of Si–C bonds in the intergranular amorphous film, which is also evident from the sawtooth jumps in the stress-strain response

Plasma-assisted ignition for a kerosene fueled scramjet at Mach 1.8

By using a plasma jet (PJ) torch with 1.5 kW input power as an igniter, successful ignition for liquid-kerosene fueled combustion experiment was conducted in a direct-connected supersonic test facility. The incoming flow has total temperature of 950 K and local Mach number of 1.8, corresponding to Mach 4 flight condition. In this study, several optical techniques, including high speed photography, high speed schlieren photography, and planar laser scattering (PLS) technique, were combined to study the ignition process, flame propagation, and mixing features of liquid kerosene fuel with air around the cavity. The effect of fuel injection position, injection pressure, and feedstock gas on ignition performance has been analyzed. The results indicate that local mixing is a critical factor for ignition. It is also shown that the PJ torch with N-2 + H-2 feedstock is superior to the PJ torch with N-2 feedstock for the ignition of liquid-kerosene fuel. These results are valuable for the future optimization of kerosene-fueled scramjet engine when using a PJ torch as an igniter

Pan-cancer analysis of whole genomes

Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale(1-3). Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter(4); identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation(5,6); analyses timings and patterns of tumour evolution(7); describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity(8,9); and evaluates a range of more-specialized features of cancer genomes(8,10-18).Peer reviewe

Novel Application of Imprinting Lithography for Multi-bit Ferroelectric Memories

This thesis is about an innovative application of nanoimprinting lithography in organic ferroelectric memories, which can achieve multi-bit data storage. Multi-bit data storage, defined here as storage of multiple bits in a single device cell, can potentially make higher density ferroelectric memory at a lower price. The idea is based on ferroelectric response with regard to ferroelectric film thickness. Two kinds of memory cells were fabricated to test the functionality and performance of the proposed concept. After optimizing the thermal nano-imprinting process to replicate periodicity micro-structure to a ferroelectric poly(vinylidene fluoride-trifluoroethylene) film, we first fabricated the ferroelectric capacitor cells with the imprinted polymer film. The fabricated cells, with sizes down to 0.0589 mm^2, showed a promising multi-bit functionality and retention property. Four different imprinting patterns were also compared, the repeating grating structure as line: 20 um / space: 10 um represented the best multi-bit performance in terms of identification of the operation voltage for different bits. A prediction of the imprinting pattern and the ferroelectric capacitor performance were given according to the results. With the same imprinting condition, we also fabricated ferroelectric field effect transistors (FeFETs). The FeFETs with periodicity pattern of line: 20 um / space: 10 um was investigated. It is observed that, the smallest imprinted cell with a gate length of 5 um and width of 5 mm only has several nano-ampere of leakage current, which is 10^5 times smaller than the ON current. Using a drain voltage of 50 mV, states can be read out easily. It is evident that the four states of the system retain distinguishable after the 10^4 second retention test.DIMESElectrical Engineering, Mathematics and Computer Scienc

Efficient High Performance Computing on Heterogeneous Platforms

Heterogeneous platforms are mixes of different processing units in a compute node (e.g., CPUs+GPUs, CPU+MICs) or a chip package (e.g., APUs). This type of platforms keeps gaining popularity in various computer systems ranging from supercomputers to mobile devices. In this context, improving their efficiency and usability has become increasingly important. In this thesis, we develop systematic methods for a large variety of data parallel applications to efficiently utilize heterogeneous platforms. Specifically, (1) we evaluate the suitability of OpenCL as a unified programming model for heterogeneous computing and improve OpenCL's efficiency for programming heterogenous platforms; (2) we develop a workload partitioning framework to accelerate imbalanced applications on heterogeneous platforms, where we match the heterogeneity of the platform with the imbalance of the workload; (3) we propose a model-based prediction method to correctly and quickly predict the optimal workload partitioning, maximizing the performance gain while speeding up the partitioning process; (4) we generalize a systematic workload partitioning approach which improves performance for both balanced and imbalanced applications, for applications with different datasets and execution scenarios, and for platforms with different hardware mixes; (5) we design an application analyzer that analyzes application kernel structures and enables different partitioning strategies accordingly to obtain both high performance and wide applicability for workload partitioning on heterogeneous platforms. To summarize, this thesis demonstrates that heterogeneous platforms are the right solution, performance-wise, for many classes of data parallel applications, and shows how high performance can be achieved systematically.Software and Computer TechnologyElectrical Engineering, Mathematics and Computer Scienc

60GHz Quadrature Voltage-Controlled Oscillator for Radar Application

A voltage controlled oscillator (VCO) is an integral part of a phase lock loop (PLL) which by itself is the core of the frequency reference in a radar system. The generation of the in-phase and quadratue signals is crucial for many radar applications. A 60GHz quadrature voltage controlled oscillator (QVCO) is presented in this thesis. The design is implemented in 130nm SiGe BiCMOS technology from STMicroelectronics with an fT of 220GHz and fMax of 320GHz. Two Colpitts oscillator cores are series coupled to each other to generate the required in-phase and quadrature signals. The QVCO achieves a simulated tuning range from 53GHz to 59GHz with a tuning voltage from 0.5V to 2.3V. The phase noise is better than -76dBc/Hz at 1MHz offset from the carrier over the whole frequency tuning range. The total power consumption for the QVCO core is 28mW. The chip has been submitted for tape out in June 2010 and will be back for measurement in due time.MicroelectronicsMicroelectronics & Computer EngineeringElectrical Engineering, Mathematics and Computer Scienc

Dipolar spin waves in uniaxial easy-axis antiferromagnets: A natural topological nodal-line semimetal

The existence of magnetostatic surface spin waves in ferromagnets, known as the Damon-Eshbach mode, was recently demonstrated to originate from the topology of the dipole-dipole interaction. In this work, we study the topological characteristics of magnons in easy-axis antiferromagnets with uniaxial anisotropy. The dipolar spin waves are found to be, driven by the dipole-dipole interaction, in a topological nodal-line semimetal phase, which hosts Damon-Eshbach-type surface modes due to the bulk-edge correspondence. The long-wavelength character of dipolar spin waves makes our proposal valid for any natural uniaxial easy-axis antiferromagnet and, thus, enriches the candidates of topological magnonic materials. In contrast to the nonreciprocal property in the ferromagnetic case, surface modes with opposite momentum coexist at each surface, but with different chiralities. Such chirality-momentum or spin-momentum locking, similar to that of electronic surface states in topological insulators, offers the opportunity to design novel chirality-based magnonic devices in antiferromagnets.Publisher Copyright: © 2020 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.QN/Akhmerov Grou

Magnetostrictively Induced Stationary Entanglement between Two Microwave Fields

We present a scheme to entangle two microwave fields by using the nonlinear magnetostrictive interaction in a ferrimagnet. The magnetostrictive interaction enables the coupling between a magnon mode (spin wave) and a mechanical mode in the ferrimagnet, and the magnon mode simultaneously couples to two microwave cavity fields via the magnetic dipole interaction. The magnon-phonon coupling is enhanced by directly driving the ferrimagnet with a strong red-detuned microwave field, and the driving photons are scattered onto two sidebands induced by the mechanical motion. We show that two cavity fields can be prepared in a stationary entangled state if they are, respectively, resonant with two mechanical sidebands. The present scheme illustrates a new mechanism for creating entangled states of optical fields and enables potential applications in quantum information science and quantum tasks that require entangled microwave fields.QN/Groeblacher La

Depth Annotations: Designing Depth of a Single Image for Depth-based Effects

We present a novel pipeline to generate a depth map from a single image that can be used as input for a variety of artistic depth-based effects. In such a context, the depth maps do not have to be perfect but are rather designed with respect to a desired result. Consequently, our solution centers around user interaction and relies on a scribble-based depth editing. The annotations can be sparse, as the depth map is generated by a diffusion process, which is guided by image features. We support a variety of controls, such as a non-linear depth mapping, a steering mechanism for the diffusion (e.g., directionality, emphasis, or reduction of the influence of image cues), and besides absolute, we also support relative depth indications. In case that a depth estimate is available from an automatic solution, we illustrate how this information can be integrated in form of a depth palette, that allows the user to transfer depth values via a painting metaphor. We demonstrate a variety of artistic 3D results, including wiggle stereoscopy, artistic abstractions, haze, unsharp masking, and depth of field.Comp Graphics & Visualisatio