Adaptive Discretization for Computerized Tomography

Two adaptive discretization frameworks are tested for computerized tomography (CT) data reconstruction. Removal of inactive pixels is primary motivation. Efficient and user independent entropy optimized masking is employed for spatial filtering purposes. Density of nodes at high gradient of reconstructed physical property is used as adaptation criterion. An alternative option, independent from noisy projection data and nature of the physical properties, is also discussed. Sensitivity analysis between the uniform and nonuniform (evolved via adaptive route) reconstruction grid reveals the utility of nonuniform grids. Iterative and transform based reconstruction techniques are used. Outcomes are tested successfully on three real world projection data from two different compact CT setups and one commercial high-resolution micro-CT scanner.     

空间统计在长江流域大米镉分布特征研究的应用

目的通过研究长江流域大米中镉含量的空间分布特征,为治理粮食作物镉污染提供科学依据。方法利用空间自相关对镉污染的聚集水平进行分析。结果湘江、岷江、涪江、沱江、青衣江、大度河支流流域的大米中镉含量高于长江流域的其他地区,2015年长江流域大米中镉含量的全局Moran's I指数值为0.596,在α=0.01水平上具有统计学意义。长江流域的大米样品中镉含量呈现中度的空间聚集性。湘江支流流域、岷江支流流域形成了2个"高-高"聚集区域,在鸭池河及其周边地区形成了一个典型的"低-低"聚集区域。结论长江流域整体上呈现中度的空间聚集性,局部地区呈现出空间异质性。     

Beta-Binomial删除信道中的喷泉码文件传输协议

由于命名数据网络(NDN,Named-Data Networking)无环路、逐包、逐跳转发的特点,使得数据包回传成功率降低,而传统的TCP/IP协议中的ARQ和ACK机制对于多播会话不再适用.由于NDN中的传输信道可以等效为二进制删除信道,因此可以通过应用层编码来实现文件的可靠传输.传统的信道编码技术如卷积码、级联码和RS码等复杂度较高,而将NDN与低复杂度的喷泉码的结合可以实现分布式的存储架构,因而可通过喷泉编码在应用层协议中实现可靠的纠删机制,保证整体文件的传输可靠性.以往的研究一般是基于确定的删除概率信道模型,但是由于网络的异构性和信道噪声等因素影响,可能会造成信道丢包概率呈随机性分布.因此,本文在Beta-Binomial分布模型的前提下,根据贝叶斯统计的先验信息和中心极限定理,对随机概率下的纠删信道的文件可靠传输协议进行了数学建模和理论推导.仿真结果显示此模型更具有普适性,此传输协议可在信道状况未知的前提下从理论上求出最小发包数,减少冗余编码包,提高文件整体的投递成功率,在保证传输可靠性的同时有效提升协议传输效率.     

信息技术在医院病案统计中的应用

伴随着我国综合实力的不断提升,信息技术获得了突飞猛进的发展,如今,医疗改革如火如荼地进行,医院的信息管理工作同以往相比较也实现了极大的发展。病案统计工作是指相关工作人员对医院中患者的信息进行全面统计,若是这项工作完成得足够出色,会给医院后续的信息查询工作带来诸多方便和快捷,也能够在某种程度上使医院管理效率和质量实现一定幅度的提升。因此,将信息技术和医院的病案工管理工作进行密切结合,就成为病案管理人员应当重点思考的问题。病案统计工作是医院管理工作中的一个重点环节,病案统计结果能够为医院整体绩效带来十分深远的影响。因此,投入更多时间和精力来提高对这项工作的重视,显得十分关键和重要。文章对信息技术在医院病案统计中的应用展开了分析。     

基于空间统计方法的蔬菜中农药残留风险分析

目的分析蔬菜中农药残留空间格局分布变化及规律,找到聚集热点区域,为蔬菜中农药残留监测、监管提供科学依据。方法用空间统计方法对某省2014—2016年蔬菜中农药残留监测信息结合地理信息进行空间格局分布及空间聚集性分析。结果 2014—2016年区域内监测的蔬菜中农药残留检出率和超标率两者分布格局较一致,但三年对比变化较大,检出较高区域集中分布在西南部和东北部;超标率涉及区县较少,散在分布在西南部和东北部。2014年监测区域的蔬菜中农药检出率全局存在正相关性(P0.05,Moran's I=0.410),局部相关主要分布在西南部、北部和南部地区;2016年监测区域的蔬菜中农药超标率全局存在正相关性(P0.05,Moran's I=0.111),局部相关主要分布在西南部地区;2016年监测区域的蔬菜中农药检出率全局存在负相关性(P0.05,Moran's I=-0.087),局部相关主要分布在中部地区。时空扫描统计量分析结果显示监测区域内超标率和检出率均有聚集性,超标率有一个聚类区域(LLR=27.11,P0.05,RR=20.04),分布在东北部区县;检出率有两个聚类区域,一类聚类区域(LLR=43.24,P0.05,RR=6.9)分布在东北部和南部区县,二类聚类区域(LLR=19.13,P0.05,RR=4.13)分布在西南部区县。结论 2014—2016年监测区域的蔬菜中农药残留检出率和超标率呈现较为一致的下降趋势。空间自相关性和时空扫描统计量结果显示存在聚集性,聚集区域主要为东北部和西南部邻近区县,且聚集区域的相对风险度RR值均4,提示这些聚集区县较其他区县农药残留风险高,是监管部门应该关注的热点区域。     

A statistical model for the failure of glass plates due to nickel sulfide inclusions

Nickel Sulfide (NiS) inclusions can provoke the rupture of thermally treated glass due to a phase transformation with volume increase that stresses the surrounding glass. Starting from a Pareto statistics for the population of inclusion sizes, from an assumed kinetics of the phase transformation, a micro-mechanically motivated model provides the statistical characterization of the probability of spontaneous failure of glass during lifetime. A distinction based upon the composition of NiS is used to discuss the effects of the heat soak test (HST), where glass remains at high temperature for a certain time to speed-up the phase transformation and destroy those elements with critical inclusions. Three functions à la Weibull for the probability of spontaneous rupture during lifetime are theoretically derived for the case of no HST, short HST, and long HST. In particular, the probability of collapse for long HSTs depends upon the holding time in the oven. An explanatory example shows the potentiality of the model for optimizing the HST parameters toward a target probability of failure, but experimental campaigns are needed for a proper calibration.     

Extraction of Distinguished Hyperbolic Trajectories for 2D Time-Dependent Vector Field Topology

This paper does two main contributions to 2D time-dependent vector field topology. First, we present a technique for robust, accurate, and efficient extraction of distinguished hyperbolic trajectories (DHT), the generative structures of 2D time-dependent vector field topology. It is based on refinement of initial candidate curves. In contrast to previous approaches, it is robust because the refinement converges for reasonably close initial candidates, it is accurate due to its adaptive scheme, and it is efficient due to its high convergence speed. Second, we provide a detailed evaluation and discussion of previous approaches for the extraction of DHTs and time-dependent vector field topology in general. We demonstrate the utility of our approach using analytical flows, as well as data from computational fluid dynamics.     

No-reference quality assessment of dynamic sports videos based on a spatiotemporal motion model

This paper proposes an approach to improve the performance of no-reference video quality assessment for sports videos with dynamic motion scenes using an efficient spatiotemporal model. In the proposed method, we divide the video sequences into video blocks and apply a 3D shearlet transform that can efficiently extract primary spatiotemporal features to capture dynamic natural motion scene statistics from the incoming video blocks. The concatenation of a deep residual bidirectional gated recurrent neural network and logistic regression is used to learn the spatiotemporal correlation more robustly and predict the perceptual quality score. In addition, conditional video block-wise constraints are incorporated into the objective function to improve quality estimation performance for the entire video. The experimental results show that the proposed method extracts spatiotemporal motion information more effectively and predicts the video quality with higher accuracy than the conventional no-reference video quality assessment methods.