Use of ASAR images to study the evolution of the Prestige oil spill off the Galician coast

Space‐borne synthetic aperture radar has been proven to be a useful tool for ocean oil spill monitoring due to its large coverage, independence of the day–night cycle and all‐weather capability. In this paper, a method for oil spill detection based on a visual interpretation was applied to two consecutive Advanced Synthetic Aperture Radar (ASAR) images acquired during the Prestige oil spill off the Spanish coast. The obtained oil spill information was integrated into a Geographical Information System (GIS) database in order to study the spatial distribution and the evolution of the slicks between both days, in addition to carrying out a comparison with field observations. The results show the great capability of monitoring and forecasting marine oil spills caused by large oil tanker accidents by means of the use of radar imagery jointly with other information, such as wind data or in situ observations.     

Application of AVIRIS data in detection of oil-induced vegetation stress and cover change at Jornada, New Mexico

On June 1, 2000, an oil spill accident occurred along transportation pipeline located in the Jornada Experimental Range (USDA), Jornada, New Mexico, a long-term ecological research (LTER). In order to detect potential vegetation stress caused by the accident, two AVIRIS data sets of the oil spill area, before and after the oil release, are analyzed and the reliability of several techniques in the detection of vegetation stress is examined.The polynomial fitting and Lagrangian interpolation, and spectral mixture analysis (SMA) are applied to the AVIRIS data sets. The first two methods are applied for the detection of the “red-edge” shift in vegetation reflectance spectra, and the last for the detection of change in vegetation fraction. The results indicate that the polynomial fitting and Lagrangian interpolation both are able to detect a red-shift of the vegetation “red-edge”, but the latter's performance depends on the band combination used and is sensitive to data noise. The polynomial fitting results are inconsistent in detection of “the red-edge” shift, while Lagrangian interpolation is not. Within the oil spill area, the fraction estimates of vegetation resulting from SMA demonstrate a decrease (10-30%) of the vegetation fraction after the accident, indicating stressed vegetation and cover change. The result also indicates that areas of extremely large decrease (>40%) in plant cover outside of the oil spill area is due to the response of grasses due to the water stress in 2000, and that the integration of some auxiliary data on ecological and climatological data with the analysis of remotely sensed data is thus very important to the interpretation of the detection results. A sensitivity analysis indicates that the detected vegetation cover change is insensitive to the noise introduced by the radiometric normalization.     

Dynamic mapping of nature values to support prioritization of coastal oil combating

Due to the continuing demand of oil for energy production and to manufacture various consumables the threat to coastal ecosystems by maritime oil transport remains at a high level. Clearly there is a need for tools that can be used in mitigating the environmental damage incurred by oil accidents. This paper presents a dynamic mapping application for comparing the ecological value of the shoreline of the Gulf of Finland to guide decisions on where to lay oil booms after an oil spill accident. The maps were required to combine conservational value of different species occurrences, the estimated level of oil exposure, the estimated recovery potential of the occurrences following the accident, and the efficiency of oil booms to safeguard the species inhabiting the occurrences. The mapping was tested in representative cases. The results indicate that the ranking of neighbouring shoreline streches changes depending on weather conditions and on choices made in developing the significance criteria. To the authors knowledge this work represents a unique effort in combining biological and geospatial expertise to provide decision support for oil combating. Such support is essential should ecological values truly be included in oil combating planning and management.     

长江感潮河段溢油风险评价体系构建及应用

长江感潮河段水动力条件复杂,对该水域溢油事故缺少相应的风险评价指标体系。为科学评价长江感潮河段溢油风险,从溢油事故对上游水体、敏感点、敏感区影响 3 个要素出发,构建风险评价指标体系,包括危害区特征、危害期特征共 23 个指标。应用该指标体系,基于 EFDC 二维水动力-油粒子模型,以长江南京段水域某码头溢油事故为研究对象,开展溢油风险评价,模拟计算涨急、落急、涨憩、落憩 4 种典型事故发生工况下的风险评价指标值。结果表明;事故发生在落急或涨憩时刻时不会对上游水域产生影响,发生在落憩时刻时对事故点上游水域影响距离最远,发生在落急时刻时将最快影响到下游的敏感点和敏感区,持续时间与水动力特性密切相关。建立的评价指标体系可以较为全面地刻画溢油风险影响特征,为长江感潮河段溢油风险评价提供量化指标和评价工具。     

A probabilistic model for predicting software development effort

Recently, Bayesian probabilistic models have been used for predicting software development effort. One of the reasons for the interest in the use of Bayesian probabilistic models, when compared to traditional point forecast estimation models, is that Bayesian models provide tools for risk estimation and allow decision-makers to combine historical data with subjective expert estimates. In this paper, we use a Bayesian network model and illustrate how a belief updating procedure can be used to incorporate decision-making risks. We develop a causal model from the literature and, using a data set of 33 real-world software projects, we illustrate how decision-making risks can be incorporated in the Bayesian networks. We compare the predictive performance of the Bayesian model with popular nonparametric neural-network and regression tree forecasting models and show that the Bayesian model is a competitive model for forecasting software development effort.     

基于抽象故障树的化工事故预警

情景是分析事件的发生、发展及可能的后果的有效机制,然而,基于情景的预警机制或缺乏有效的模型支撑或受制于模型的局限性,实践中难以推广.抽象故障树是同类事故故障树的高层抽象,综合历史案例与专家经验,能够刻画事故的成因的机理、情景演化过程及可能的后果,能够有效支撑基于情景的预警分析.提出一种基于抽象故障树的化工事故预警方法,基于抽象映射计算事件危害度及节点重要度,将情景演化的割集模型转换为贝叶斯网络模型,采用Board法对事故危害进行风险度量和防御事件排序,实现基于情景的不同演化路径的事故风险预测及最佳应对策略推荐,实验结果显示了该方法用于事故分析预警的有效性.     

Oil spill detection from SAR intensity imagery using a marked point process

This paper presents a new algorithm for the detection of oil spill from SAR intensity images. The proposed algorithm combines the marked point process, Bayesian inference and Markov Chain Monte Carlo (MCMC) technique. In this paper, the candidates of oil spills or dark spots in a SAR intensity image are characterized by a Poisson marked point process. The marked point process is formed by a group of random points (as a point process modelling the locations of oil spills) and a set of parameters including geometric parameters of windows centred at the random points and gamma distribution parameters (as the marks attaching to each point). As a result, the candidates of oil spills are represented by a group of windows, in which the intensities of pixels follow independent and identical gamma distribution with lower mean than that for the identical gamma distribution of the pixels out of windows. Following the Bayesian paradigm, the posterior distribution, which characterizes the locations and statistical distributions of oil spills, can be obtained up to a normalizing constant. In order to simulate from the posterior distribution and to estimate the parameters of the posterior distribution, the Revisable Jump MCMC (RJMCMC) algorithm is used. The optimal locations and sizes of dark spots are obtained by a maximum a posteriori (MAP) algorithm. The proposed approach is tested using Radarsat-1 SAR images with oil spills indicated by human analysts. The results show that the proposed approach works well and is very promising.     

A bayesian belief network based model for predicting software faults in early phase of software development process

It is always better to have an idea about the future situation of a present work. Prediction of software faults in the early phase of software development life cycle can facilitate to the software personnel to achieve their desired software product. Early prediction is of great importance for optimizing the development cost of a software project. The present study proposes a methodology based on Bayesian belief network, developed to predict total number of faults and to reach a target value of total number of faults during early development phase of software lifecycle. The model has been carried out using the information from similar or earlier version software projects, domain expert’s opinion and the software metrics. Interval type-2 fuzzy logic has been applied for obtaining the conditional probability values in the node probability tables of the belief network. The output pattern corresponding to the total number of faults has been identified by artificial neural network using the input pattern from similar or earlier project data. The proposed Bayesian framework facilitates software personnel to gain the required information about software metrics at early phase for achieving targeted number of software faults. The proposed model has been applied on twenty six software project data. Results have been validated by different statistical comparison criterion. The performance of the proposed approach has been compared with some existing early fault prediction models.     

Multi-objective optimization based privacy preserving distributed data mining in Peer-to-Peer networks

This paper proposes a scalable, local privacy-preserving algorithm for distributed Peer-to-Peer (P2P) data aggregation useful for many advanced data mining/analysis tasks such as average/sum computation, decision tree induction, feature selection, and more. Unlike most multi-party privacy-preserving data mining algorithms, this approach works in an asynchronous manner through local interactions and it is highly scalable. It particularly deals with the distributed computation of the sum of a set of numbers stored at different peers in a P2P network in the context of a P2P web mining application. The proposed optimization-based privacy-preserving technique for computing the sum allows different peers to specify different privacy requirements without having to adhere to a global set of parameters for the chosen privacy model. Since distributed sum computation is a frequently used primitive, the proposed approach is likely to have significant impact on many data mining tasks such as multi-party privacy-preserving clustering, frequent itemset mining, and statistical aggregate computation.     

Distributed system anomaly detection using deep learning-based log analysis

Anomaly detection is a key step in ensuring the security and reliability of large-scale distributed systems. Analyzing system logs through artificial intelligence methods can quickly detect anomalies and thus help maintenance personnel to maintain system security. Most of the current works only focus on the temporal or spatial features of distributed system logs, and they cannot sufficiently extract the global features of distributed system logs to achieve a good correct rate of anomaly detection. To further address the shortcomings of existing methods, this paper proposes a deep learning model with global spatiotemporal features to detect the presence of anomalies in distributed system logs. First, we extract semi-structured log events from log templates and model them as natural language. In addition, we focus on the temporal characteristics of logs using the bidirectional long short-term memory network and the spatial invocation characteristics of logs using the Transformer. Extensive experimental evaluations show the advantages of our proposed model for distributed system log anomaly detection tasks. The optimal F1-Score on three open-source datasets and our own collected distributed system datasets reach 98.04%, 94.34%, 88.16%, and 97.40%, respectively.     

基于Web的溢油仿真系统的研究

海上溢油的危险系数越来越高,给生态环境和经济发展带来巨大威胁。为更好地防范海上溢油,提出一种基于Web的溢油仿真系统。采用系统仿真能力强大的Matlab和简化溢油模型,用Matlab Web Server构建B/S模式的服务器,提供方便快捷的海上溢油仿真分析。实践表明,该系统使用便捷、可扩展性较好。     

基于ENVISat的海洋污染性油膜雷达散射特征与扩散趋势分析

污染性海洋溢油一旦发生,快速获取油膜信息对有效控制溢油危害具有重要意义。以渤海湾一次溢油污染事件为例,利用ENVISat数据根据油膜雷达后向散射特征分析溢油的发生,并利用溢油期间的连续风场信息和连续SAR数据对比研究油膜的扩散趋势以及扩散过程中油膜尺度的变化。结果表明：污染性油膜在海上扩散的不同阶段具有不同的SAR图像特征,海上溢油雷达遥感检测分析方法与检测效果因SAR图像获取时油膜所处扩散阶段不同而有所不同,通过SAR连续观测结合辅助信息可以对污染油膜及其运动进行有效监控与预测。     

SAR影像海洋表面溢油检测方法与实现

海洋是地球的重要组成部分,它为人类提供了丰富的物质和宝贵的资源,每年海洋都承受着不同程度的侵害,其中油类污染是给海洋造成巨大危害的污染之一。而油类污染又主要来源于轮船破裂漏油以及油井平台或海底输油管道爆炸等。每次事故造成的直接经济损失达几百万至上千万不等,所以对海上溢油进行监测具有重要的意义。选用Envisat的ASAR数据进行海上溢油检测,介绍并分析了SAR图像溢油检测的一般步骤及其实现方法,通过采用单一阈值分割法、最大熵分割法和非监督分类法对影像进行目标检测,从而粗略地将影像区分为前景区域与背景区域,并结合影像的纹理特征进行分类。在纹理特征选取过程中,通过人工选取部分溢油区与非溢油区作为感兴趣区,在感兴趣区上分别统计SAR影像常用的纹理特征,并结合不同目标检测的结果以及原始影像进行基于BP神经网络的分类,得到了良好的效果。最后展望了SAR图像海洋溢油检测的发展方向。     

一种基于贝叶斯网络模型的交通事故预测方法

大部分的交通事故都可以预测.有效的交通事故预测能从很大程度上减少人员伤亡和交通阻塞.贝叶斯网络是目前不确定知识和推理领域最有效的理论模型之一.该文提出了一种基于贝叶斯网络模型理论的交通事故预测方法.在综合考虑交通事故成因的基础上利用领域专家知识构建网络模型,在已有的事故数据的基础上提出基于贝叶斯法则的学习算法,并通过计算变量间的条件概率来计算事故发生的可能性,达到事故预测的目的.文章的最后,通过历史数据进行仿真实验,对仿真结果和该模型的适用范围进行了分析.     

基于贝叶斯网的分布式软件行为运行时可信性分析

在开放、动态和复杂的网络环境中,监测与分析软件行为可信对现代分布式软件是至关重要的.针对分布式软件运行时的外在表现特征,系统地收集相关数据,根据具体交互场景建立贝叶斯网模型.利用此模型,在上下文环境中通过监测相关的数据来对软件行为运行时可信性进行分析.建网过程中,文中提出了使用“3σ原则”来离散化连续型随机变量,其在判断样本标注异常及先验参数确定等方面具有独特优势,操作方便又符合实际情况,且提高了参数学习效率;同时,文中提出了分层方法构造先验贝叶斯网思想,通过计算节点间的相关系数来逐步修正贝叶斯网结构,降低了建网的复杂性和误差.通过仿真实验,证实了本文所提出的方法在软件行为可信性分析方面较其他方法有着独特的优势.     

Software effort estimation based on the optimal Bayesian belief network

In this paper, we present a model for software effort (person-month) estimation based on three levels Bayesian network and 15 components of COCOMO and software size. The Bayesian network works with discrete intervals for nodes. However, we consider the intervals of all nodes of network as fuzzy numbers. Also, we obtain the optimal updating coefficient of effort estimation based on the concept of optimal control using Genetic algorithm and Particle swarm optimization for the COCOMO NASA database. In the other words, estimated value of effort is modified by determining the optimal coefficient. Also, we estimate the software effort with considering software quality in terms of the number of defects which is detected and removed in three steps of requirements specification, design and coding. If the number of defects is more than the specified threshold then the model is returned to the current step and an additional effort is added to the estimated effort. The results of model indicate that optimal updating coefficient obtained by genetic algorithm increases the accuracy of estimation significantly. Also, results of comparing the proposed model with the other ones indicate that the accuracy of the model is more than the other models.     

基于贝叶斯网络的列控系统安全风险评估方法

为科学评估列车运行控制系统内各危险导致的事故风险,用贝叶斯网络描述危险、风险和事故后果间的因果关系。通过识别系统中的潜在危险、危险导致事故的发生率和严重程度,结合贝叶斯网络处理不完备数据的优势,建立基于贝叶斯网络的风险评估模型,计算危险导致事故发生的可容忍危险率,判断系统能否满足安全要求并达到设定的安全目标。以美国的列车保护警报系统和I级铁路事故/事件数据库为例,利用该模型进行风险评估,结果表明4个初始危险导致的事故可容忍危险率小于规定值,验证了模型的有效性,为列控系统风险评估的具体实施方法提供了新思路。     

A predictive Bayesian data-derived multi-modal Gaussian model of sunken oil mass

Hydrodynamic modeling of sunken oil is hindered by insufficient knowledge of bottom currents. In this paper, the development of a predictive Bayesian model, SOSim, for inferring the location of sunken oil in time, based on sparse, qualitative or quantitative near-real time field data collected immediately following a spill, is described. Mapped output represents unconditional multi-modal Gaussian relative probabilities of finding oil at points across a relatively flat bay bottom, in time. The method of images is extended to address curvilinear reflecting shorelines. The model is demonstrated to locate the entire DBL-152 spill, given field data covering part of the area affected, and to project oil movement near curvilinear shoreline boundaries given simulated field data at two points in time. Limitations include accountability for discontinuous boundary conditions. Further development is recommended, including development of capability for accepting bathymetric data, for modeling continuous oil releases, and for 3-D modeling of suspended oil.     

Virtual time and virtual space

Simulation models involve the concepts oftime andspace. In designing a distribution simulation programming system, introducing a temporal construct results in a specification language for describing a changing world, introducing a spatial construct makes it possible to coordinate multiple, simultaneous, nondeterministic activities.In this paper, we present a new distributed logic programming model and discuss its implementation. A distributed program is represented by avirtual space—a set of process which are logical representations of system objects, and is evaluated with respect tovirtual time—a temporal coordinate which is used to measure computational progress and specify synchronization. The major focus of the implemention is the ability to accomplish global backtracking. The proposed implementation collects global knowledge through interprocess communication, controls global backtracking distributedly according tovirtual time anddependency relations, and capture heuristics in that earlier synchronizations may make subsequent synchronizations more likely to succeed.As compared with other distributed logic programming systems, our system provides a simpler syntax, well-defined semantics, and an efficient implementation.     

海上溢油遥感探测技术及其应用进展

介绍了海上溢油遥感探测常用的可见光、红外、紫外光学遥感器、微波辐射计、雷达、激光荧光器和油层厚度探测器等几种溢油遥感探测器的探测原理、能力及应用状况。可见光仪器的溢油探测能力非常有限；红外遥感器是有一定探测能力的最为实用的探测器；微波遥感具有全天候的特点，但空间分辨率低，识别能力也有一定的限制；而激光荧光器和油层厚度探测器等激光遥感器则是最有发展前景的一类溢油探测器。通过性能等方面的对比分析以及当前实际应用情况，分析了未来溢油遥感技术的发展趋势。