检索结果-内蒙古大学图书馆

24th International Conference on Information processing in Medical Imaging, IPMI 2015

作者： Ianuş, Andrada Drobnjak, Ivana Alexander, Daniel C. Centre for Medical Image Computing University College London London United Kingdom

Non-invasive estimation of cell size and shape is a key challenge in diffusion MRI. Changes in cell size and shape discriminate functional areas in the brain and can highlight different degrees of malignancy in cancer tumours. Consequently various methods have emerged recently that aim to measure the microscopic anisotropy of porous media such as biological tissue and aim to reflect pore eccentricity, the simplest shape feature. However, current methods assume a substrate of identical pores, and are strongly influenced by non-trivial size distribution. This paper presents a model-based approach that provides estimates of pore size and shape from diffusion MRI data. The technique uses a geometric model of randomly oriented finite cylinders with gamma distributed radii. We use Monte Carlo simulation to generate synthetic data in substrates consisting of randomly oriented cuboids with various size distributions and eccentricities. We compare the sensitivity of single and double pulsed field gradient (sPFG and dPFG) sequences to the size distribution and eccentricity and further compare different protocols of dPFG sequences with parallel and/or perpendicular pairs of gradients. The key result demonstrates that this model-based approach can provide features of pore shape (specifically eccentricity) that are independent of the size distribution unlike previous attempts to characterise microscopic anisotropy. We show further that explicitly accounting for size distribution is necessary for accurate estimates of average size and eccentricity, and a model that assumes a single size fails to recover the ground truth values. We find the most accurate parameter estimates for dPFG sequences with mixed parallel and perpendicular gradients, nevertheless all other sequences, including sPFG, show sensitivity as well. © Springer International Publishing Switzerland 2015.

关键词： Magnetic resonance imaging

来源：评论

学校读者我要写书评

暂无评论

TH-CD-303-02: A GPU-Based Iterative image Reconstruction Solver with 4D Regularization for Low-Dose Helical 4DCT

引用

Medical Physics 2015年第6PART43期42卷 3728-3729页

作者： M Guo R Li L Xing H Gao Shanghai Jiao Tong University Shanghai Shanghai Stanford University Palo Alto CA Stanford Univ School of Medicine Stanford CA

Purpose: 4DCT is an important technique for motion management in radiotherapy, but involves a significant amount of dose to patients. Low-dose helical 4DCT scans can be done by (a) lowering tube current and pulse duration, (b) increasing helical pitch, and (c) reducing data sampling. Conventional FDK methods may fail for these low-dose scan protocols due to noisy or incomplete data. We aim to develop an accurate and fast image reconstruction solver that enables dose reduction for helical 4DCT. methods: For improved accuracy, the developed solver is based on a novel 4D regularization method for CT image reconstruction, which promotes both the smoothness in spatial variables for each phase and the similarity in temporal variables between phases, in contrast with the 3D regularization method with spatial regularization only. Both 3D and 4D methods here are based on total variation. The formulated optimization problem is solved by alternating direction method of multipliers (ADMM), which is chosen for its effectiveness for solving the convex problem, and more importantly its suitability for distributed *** improved speed, the developed solver utilizes an efficient parallel algorithm for X-ray transform and its adjoint with optimized computational cost per parallel thread O (1) that takes flying focal spots into account, and multi-GPU platforms for solving such a massive parallel computing problem in helical 4DCT. Results: The solver was validated using both simulations (4D NCAT phantoms) and experimental sinogram data (Siemens, Somatom 64-slices) with low-dose, high-pitch and sparse-view helical 4DCT scans. Both the reconstructed images and quantitative results demonstrate that the 4D method improved image quality compared with the 3D method, which is in turn better than FDK. Conclusion: We have developed a fast, accurate solver that synergizes state-of-art iterative reconstruction methods and parallel computing techniques that can potentially enable low-dose,

关键词： Medical image reconstruction parallel processing Computer simulation Three dimensional image processing Dosimetry Computed tomography Medical image contrast Optimization

来源：评论

学校读者我要写书评

暂无评论

An Algebraic parallel Treecode in Arbitrary Dimensions

An Algebraic Parallel Treecode in Arbitrary Dimensions

引用

International Symposium on parallel and distributed processing (IPDPS)

作者： William B. March Bo Xiao Chenhan D. Yu George Biros Institute for Computational Engineering and Sciences The University of Texas at Austin Austin TX

We present a parallel tree code for fast kernel summation in high dimensions -- a common problem in data analysis and computational statistics. Fast kernel summations can be viewed as approximation schemes for dense kernel matrices. Tree code algorithms (or simply tree codes) construct low-rank approximations of certain off-diagonal blocks of the kernel matrix. These blocks are identified with the help of spatial data structures, typically trees. There is extensive work on tree codes and their parallelization for kernel summations in three dimensions, but there is little work on high-dimensional problems. Recently, we introduced a novel tree code, ASKIT, which resolves most of the shortcomings of existing methods. We introduce novel parallel algorithms for ASKIT, derive complexity estimates, and demonstrate scalability on synthetic, scientific, and image datasets. In particular, we introduce a local essential tree construction that extends to arbitrary dimensions in a scalable manner. We introduce data transformations for memory locality and use GPU acceleration. We report results on the "Maverick" and "Stampede" systems at the Texas Advanced Computing Centre. Our largest computations involve two billion points in 64 dimensions on 32, 768 x86 cores and 8 million points in 784 dimensions on 16, 384 x86 cores.

关键词： Kernel Approximation methods Skeleton Approximation algorithms Algorithm design and analysis Complexity theory Scalability

来源：评论

学校读者我要写书评

暂无评论

A GPU Algorithm in a distributed Computing System for 3D MRI Denoising

A GPU Algorithm in a Distributed Computing System for 3D MRI...

引用

International Conference on P2P, parallel, Grid, Cloud and Internet Computing (3PGCIC)

作者： Salvatore Cuomo Ardelio Galletti Livia Marcellino University of Naples Federico II Italy University of Naples Parthenope Italy

ISBN: (纸本)9781467394741

An interesting challenge in E-health is to perform real-time diagnosis. In many distributed computing systems the data processing stage, generally assigned on standard computational CPU environments, is a critical aspect. In particular, the analysis of magnetic resonance imaging (MRI) for improving the quality of images and helping the diagnosis requires an high computational complexity. Using Graphics processing Units (GPUs) on High Performance Computing (HPC), the images processing step can be accelerated by speeding the whole diagnosis procedure. In this paper, we propose a parallel algorithm, on a GPU environment, for MRI denoising in order to make the diagnostic system more efficient. As case study, we consider the Optimized Blockwise Non Local Means (OB-NLM) method. Its intrinsic nature makes it perfectly suited for parallelization and multithreading implementation, especially for GPUs architectures. The results show a significant improvement of the entire healthcare practice procedure in terms of performances.

关键词： Graphics processing units Instruction sets Magnetic resonance imaging Kernel Three-dimensional displays image restoration Standards

来源：评论

学校读者我要写书评

暂无评论

A distributed Framework for Event Detection in Video Surveillance Context

A Distributed Framework for Event Detection in Video Surveil...

引用

International Conference on P2P, parallel, Grid, Cloud and Internet Computing (3PGCIC)

作者： Fabio Persia Daniela D'Auria Faculty of Computer Science Free University of Bozen Italy DIETI University of Naples Federico II Italy

In latest years modern world's needs of safety caused a speed spreading of video surveillance systems, more and more frequently collocated in the most crowded places. Thus, a lot of theoretical approaches working with data coming from heterogeneous sources and defining some very complex event detection algorithms have been proposed in the literature. In this paper, we present a distributed framework for event detection in video surveillance context. The overall process is described, starting from the video frames captured by different kinds of sensors and cameras till at the end some high-level event detection algorithms performed in a distributed environment for finding potentially dangerous activities are applied. The conducted experiments confirm the efficiency achieved by our distributed framework.

关键词： Video surveillance Cameras Sensors image processing Event detection Context Libraries

来源：评论

学校读者我要写书评

暂无评论

Real-Time Depth-image-Based Rendering on GPU

Real-Time Depth-Image-Based Rendering on GPU

引用

International Conference on Cyber-Enabled distributed Computing and Knowledge Discovery, CyberC

作者： Zengzeng Sun Cheolkon Jung Samsung Electronics SRC-Xian DMC Lab/SSG Xi'an China School of Electronic Engineering Xidian University Xi'an China

ISBN: (纸本)9781467392013

In this paper, we propose real-time depth-image-based rendering (DIBR) on GPU for 1280×720 resolution. We utilize depth adaptive preprocessing and super-resolution to achieve high-quality DIBR. Moreover, we employ GPU-based parallel computing to achieve real-time DIBR. Experimental results demonstrate that the proposed method achieves superior performance in comparison with the existing methods with respect to rendering quality and computing time.

关键词： Three-dimensional displays Graphics processing units Rendering (computer graphics) Instruction sets Real-time systems Videos Filling

来源：评论

学校读者我要写书评

暂无评论

Classification of Tiangong-1 hyperspectral remote sensing image via contextual sparse coding

Classification of Tiangong-1 hyperspectral remote sensing im...

引用

International Conference on Machine Learning and Cybernetics (ICMLC)

作者： Qi Lv Yong Dou Xin Niu Jiaqing Xu Jinbo Xu School of Computer National University of Defense Technology Changsha China Science and Technology on Parallel and Distributed Processing Laboratory National University of Defense Technology Changsha China

ISBN: (纸本)9781467372220

The hyperspectral remote sensing is one of the frontier techniques in the remote sensing research fields. Applying the sparse coding model to the hyperspectral remote sensing image processing is a hot topic in hyperspectral information processing. To improve the accuracy of hyperspectral image classification, we propose a classification method based on the spatial-spectral join-t contextual sparse coding. Firstly, a dictionary is obtained by training using samples selected from the ground-truth reference data. Then, the sparse coefficients of each pixel are calculated based on the learned dictionary. Afterward, the sparse coefficients are input to the classifier and the final classification result is obtained. The visible and near-infrared hyperspectral remote sensing image collected by Tiangong-1 in Chaoyang District of Beijing is used to evaluate the performance of the proposed approach. Experimental results show that the proposed method yields the best classification performance with the overall accuracy of 95.74% and the Kappa coefficient of 0.9476 in comparison with other classification methods.

关键词： Hyperspectral image Remote sensing Sparse coding Sparse coding Classification methods remote sensing hyperspectral remote sensing hyperspectral imagery image classification

来源：评论

学校读者我要写书评

暂无评论

Reliability Analysis of Highly Redundant distributed Storage Systems with Dynamic Refuging

Reliability Analysis of Highly Redundant Distributed Storage...

引用

Euromicro Conference on parallel, distributed and Network-Based processing

作者： Hiroaki Akutsu Kazunori Ueda Takeru Chiba Tomohiro Kawaguchi Norio Shimozono Yokohama Research Laboratory Hitachi Ltd. Yokohama Japan

In recent data centres, large-scale storage systems storing big data comprise thousands of large-capacity drives. Our goal is to establish a method for building highly reliable storage systems using more than a thousand low-cost large-capacity drives. Some large-scale storage systems protect data by erasure coding to prevent data loss. As the redundancy level of erasure coding is increased, the probability of data loss will decrease, but the increase in normal data write operation and additional storage for coding will be incurred. We therefore need to achieve high reliability at the lowest possible redundancy level. There are two concerns regarding reliability in large-scale storage systems: (i) as the number of drives increases, systems are more subject to multiple drive failures and (ii) distributing stripes among many drives can speed up the rebuild time but increase the risk of data loss due to multiple drive failures. These concerns were not addressed in prior quantitative reliability studies based on realistic settings. In this work, we analyze the reliability of large-scale storage systems with distributed stripes, focusing on an effective rebuild method which we call Dynamic Refuging. Dynamic Refuging rebuilds failed storage areas from those with the lowest redundancy and strategically selects blocks to read for repairing lost data. We modeled the dynamically changing amount of storage at each redundancy level due to multiple drive failures, and performed reliability analysis with Monte Carlo simulation using realistic drive failure characteristics. When stripes with redundancy level 3 were sufficiently distributed and rebuilt by Dynamic Refuging, we found that the probability of data loss decreased by two orders of magnitude for systems with 384 or more drives compared to normal RAID. This technique turned out to scale well, and a system with 1536 inexpensive drives attained lower data loss probability than RAID 6 with 16 enterprise-class drives.

关键词： Redundancy Drives Encoding distributed databases Prefetching Approximation methods

来源：评论

学校读者我要写书评

暂无评论

An Efficient Architecture for parallel Skyline Computation over Large distributed Datasets

引用

JOURNAL OF INTERNET TECHNOLOGY 2014年第4期15卷 577-588页

作者： Li, He Jang, Sumin Yoo, Jaesoo Xidian Univ Sch Software Xidian Peoples R China Chungbuk Natl Univ Dept Informat & Commun Engn Cheongju South Korea Elect & Telecommun Res Inst Cheongju South Korea

The skyline query has been received much attention as an important operator in database systems for multi-preference analysis and decision making. Most of the previous works have focused on processing skyline queries on centralized data sets. However, the related data in real applications are practically scattered at several different servers. The skyline query computation in distributed environments is needed to gather a large number of data from the connected servers. The existing methods for a skyline query in distributed environments have two problems: (i) They have slow processing time for a skyline query. (ii) Most of the transferred data among servers in the network are unnecessary. In this paper, we propose a multi-layer grid method for efficiently processing a skyline query in distributed environments. The proposed method minimizes the unnecessary transferred data by using the grid mechanism. Experiments based on synthetic data sets and real data sets show that our proposed method outperforms the existing methods.

关键词： Skyline query distributed skyline query Large distributed dataset parallel computation

来源：评论

学校读者我要写书评

暂无评论

基于FPGA的数字化眼科超声成像中信号处理算法的研究与实现

引用

中国医疗器械杂志 2015年第1期39卷 1-4页

作者：方思敏周盛王晓春叶青盛田玲计建军王延群北京协和医学院中国医学科学院生物医学工程研究所天津市300192 天津市眼科医学设备技术工程中心天津市300384

目的基于FPGA对眼科超声诊断仪中的信号处理算法进行设计和改进。方法在Quartus ii中用Verilog HDL硬件语言实现全并行分布式动态滤波、数字正交检波、二叉树法对数压缩三大信号处理模块。结果相对原有系统,硬件开销减少,整体成像更为清... 详细信息

目的基于FPGA对眼科超声诊断仪中的信号处理算法进行设计和改进。方法在Quartus ii中用Verilog HDL硬件语言实现全并行分布式动态滤波、数字正交检波、二叉树法对数压缩三大信号处理模块。结果相对原有系统,硬件开销减少,整体成像更为清晰,眼球深部的信息更为完整,探测深度由原来的5 cm提高到6 cm。结论所设计的算法达到了设计要求,能够有效提高现有设备的成像质量,实现了系统优化。

关键词：眼科超声数字信号处理动态滤波正交检波对数压缩

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：