2,225 research outputs found
Low-dimensional exact coherent states in plane Couette flow
No full textA new approach to understanding the dynamics of moderate-Reynolds number wall bounded flows has emerged recently, based on the computation of steady (equilibrium) or exactly recurring (periodic) solutions of the Navier-Stokes equations. Such solutions are thought to represent coherent structures, and the connections in state space between these solutions can explain the dynamics and self-sustaining nature of wall-bounded turbulent flows.Herein new equilibrium solution branches for plane Couette flow are reported which add to the inventory of known solution branches. The exact solutions are found by projecting known equilibria onto the resolvent modes of McKeon and Sharma (2010 to generate approximate solutions that are subsequently used as seeds in a Newto Krylov-hookstep search. Searches initialised with these projections have a convergence rate of 96%. The low-dimensional nature of the resulting equilibria is attributed to the projection generated by the resolvent model; resolvent modes for a given equilibrium solution span a low-dimensional space which the solution approximately inhabits. This property is exploited to generate new branches of equilibria in plane Couette flow, and to jump to known branches. The new branches include bifurcations from previously known bifurcation curves and a disconnected bifurcation curve which displays interesting behaviour when continued in Reynolds number. The unstable manifolds of the new equilibria are computed to expand the known state space structure of plane Couette flow.Additionally, ten new periodic orbits in plane Couette flow are found by projecting known periodic orbits and quasi-recurrent segments of turbulent flows onto the resolvent modes of McKeon and Sharma (2010) to generate low-order representations of periodic flow, points along which are then used as initial conditions in a Newton-Krylov-hookstep search. Moreover, projections of periodic orbits find one new equilibrium solution. The new periodic solutions are in the neighbourhoods of previously known orbits and reveal the geometry of state space in the region separating the laminar and turbulent attractors. We show that the periodic orbits are appropriate representations of the self-sustaining process proposed by Waleffe (1997) and we examine their effect on turbulent trajectories in state space
Implementation of multi-threaded erasure coding under multi-processing environments
No full textŞefik Şuayb Arslan (MEF Author)Galois alan aritmetiği depolama ve iletişim cihazlarını veri kayıplarına karşı korumak için Reed-Solomon silme kodlarının temelini oluşturmaktadır. Galois alan aritmeti^ginin en güncel uygulamaları hızlı Galois alan hesaplamaları yapmamıza imkan sağlayan Intel’in SIMD eklerinde olduğu gibi 128-bitlik işlemci vektör talimatlarına dayanmaktadır. Buna rağmen, bu uygulamalar çoklu–dizin ve çoklu–süreçli ortamlara göre optimize edilmemiştir. Diğer taraftan, sunucuların çoklu istekleri eş zamanlı olarak yerine getirmesi ve donanımın sağladığı tüm paralelliği kodlama yükünü etkili yürütmek için kullanması arzu edilmektedir. Bu makale silme kodlarının çoklu-dizin işlemcilerle çoklu–süreçli ortamlarda nasıl kullanılaca^gının detaylarını sunmakta ve tek dizinli uygulamalara göre emtia mikro işlemciler ve Jerasure 2.0 yazılım kütüphanesini kullanarak önemli ölçüde performans artışının olabileceğini göstermektedir.WOS:0003912509004202-s2.0-84982843904Conference Proceedings Citation Index- ScienceProceedings PaperMayısYÖK - 2015-1
Automatic Prostate Cancer Grading Using Deep Architectures
No full textProstate cancer is the second most aggressive type of cancer among men aged over 45, and it has a major effect on people's lives. Early diagnosis and grading of prostate cancer from tissue images is necessary. Large scale inter observer reproducibility exists in grading the prostate biopsies. This leads us to move towards a computer based model that can accurately detect and grade the cancerous prostate from non-cancerous one. The paper is focused on deep learning based models to automatically grade the prostate cancer from tissue microarray images. Deep learning models directly learn the features via convolutional layers. Two datasets have been used for implementation of our proposed model, Harvard dataset and Gleason Challenge 2019. Our proposed UNET based architecture is used for training as well as validation and testing. We used four different deep learning models, VGG19, ResNet50, Mobilenetv2 and ResNext50 for our UNET based encoder. With our proposed framework, we have achieved 0.728 and 0.732 average Cohen's kappa with F1 on both datasets respectively. The results show that our proposed UNET based deep learning model shows better performance as compared to other state of the art models
Supplemental Material - Enhancement in creep resistance of pristine polystyrene with incorporation of exfoliated 2D graphene nanosheets at low filler loading
No full textSupplemental material for Enhancement in creep resistance of pristine polystyrene with incorporation of exfoliated 2D graphene nanosheets at low filler loading by Arfa Malik, Hassan Raza, Arslan Ahmad, Muhammad Rafi Raza and Muhammad Usama Arshad in Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science</p
Supplemental Material - Enhancement in creep resistance of pristine polystyrene with incorporation of exfoliated 2D graphene nanosheets at low filler loading
No full textSupplemental material for Enhancement in creep resistance of pristine polystyrene with incorporation of exfoliated 2D graphene nanosheets at low filler loading by Arfa Malik, Hassan Raza, Arslan Ahmad, Muhammad Rafi Raza and Muhammad Usama Arshad in Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science</p
Foreign Policy Sonata: Analyzing Pakistan's Diplomatic Maneuvers in the Strategic Coercion Pas de Deux
No full textData for: Understanding Occupant Behaviors in Dynamic Environments using OBiDE Framework
No full textTwo data files are provided. The first one carry the spatio-temporal data of occupants. The second file contains the description of the building information from where the dataset is collected. This dataset is already in-review by Data in Brief journal
Data for: BIM-based Intrusion Detection System using Semantic Trajectories for Dynamic Environments
No full textSpatio-temporal data and an OSM file of a building
Next-Generation data storage: Transistor and DNA
No full textŞefik Şuayb Arslan (MEF Author)With the generation of diverse data growing at exponential rates, investigating better digital storage media is inevitable. Currently, one solution is the utilization of solid-state based memory devices, which offer several desirable characteristics, including very fast write/read operations, scalability, and reduced fabrication costs. However, with the increased need for long term and large storage space, their data retention capabilities drastically decline. Another emerging storage technology on the horizon is the biotechnological based DNA storage, which renders a phenomenal storage capacities. In this paper, basics of these two promising storage technologies are reviewed and their potential future trends are discussed. © 2018 IEEE.WOS:0005114485002812-s2.0-85050802802Conference Proceedings Citation Index- ScienceProceedings PaperMayısYÖK - 2017-1
A joint dedupe-fountain coded archival storage
No full textŞefik Şuayb Arslan (MEF Author)##nofulltext##An erasure-coded archival file storage system is presented using a chunk-based deduplication mechanism and fountain codes for space/time efficient operation. Unlike traditional archival storage, this proposal considers the deduplication operation together with correction coding in order to provide a reliable storage solution. The building blocks of deduplication and fountain coding processes are judiciously interleaved to present two novel ideas, reducing memory footprint with weaker hashing and dealing with the increased collisions using correction coding, and applying unequal error protection to deduplicated chunks for increased availability. The combination of these two novel ideas made the performance of the proposed system stand out. For example, it is shown to outperform one of the replication-based as well as RAID data protection schemes. The proposed system also addresses some of the fundamental challenges of today's low-cost deduplicated data storage systems such as hash collisions, disk bottleneck and RAM overflow problems, securing savings up to 90% regular RAM use.WOS:0004248721040662-s2.0-85028335901Conference Proceedings Citation Index- ScienceProceedings PaperMayısYÖK - 2016-1
- …
