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CardioMix:a multimodal image-based classification pipeline for enhanced ECG diagnosis
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作者 Kira Sam Shah Nawaz Raja Vavekanand 《Medical Data Mining》 2025年第1期50-55,共6页
Background:Irregular heartbeats can have serious health implications if left undetected and untreated for an extended period of time.Methods:This study leverages machine learning(ML)techniques to classify electrocardi... Background:Irregular heartbeats can have serious health implications if left undetected and untreated for an extended period of time.Methods:This study leverages machine learning(ML)techniques to classify electrocardiogram(ECG)heartbeats,comparing traditional feature-based ML methods with innovative image-based approaches.The dataset underwent rigorous preprocessing,including down-sampling,frequency filtering,beat segmentation,and normalization.Two methodologies were explored:(1)handcrafted feature extraction,utilizing metrics like heart rate variability and RR distances with LightGBM classifiers,and(2)image transformation of ECG signals using Gramian Angular Field(GAF),Markov Transition Field(MTF),and Recurrence Plot(RP),enabling multimodal input for convolutional neural networks(CNNs).The Synthetic Minority Oversampling Technique(SMOTE)addressed data imbalance,significantly improving minority-class metrics.Results:The handcrafted feature approach achieved notable performance,with LightGBM excelling in precision and recall.Image-based classification further enhanced outcomes,with a custom Inception-based CNN,attaining an 85%F1 score and 97%accuracy using combined GAF,MTF,and RP transformations.Statistical analyses confirmed the significance of these improvements.Conclusion:This work highlights the potential of ML for cardiac irregularities detection,demonstrating that combining advanced preprocessing,feature engineering,and state-of-the-art neural networks can improve classification accuracy.These findings contribute to advancing AI-driven diagnostic tools,offering promising implications for cardiovascular healthcare. 展开更多
关键词 irregular heartbeats ECG signals MULTIMODAL image-based classifications
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ExplainableDetector:Exploring transformer-based language modeling approach for SMS spam detection with explainability analysis
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作者 Mohammad Amaz Uddin Muhammad Nazrul Islam +2 位作者 Leandros Maglaras Helge Janicke Iqbal H.Sarker 《Digital Communications and Networks》 2025年第5期1504-1518,共15页
Short Message Service(SMS)is a widely used and cost-effective communication medium that has unfortunately become a frequent target for unsolicited messages-commonly known as SMS spam.With the rapid adoption of smartph... Short Message Service(SMS)is a widely used and cost-effective communication medium that has unfortunately become a frequent target for unsolicited messages-commonly known as SMS spam.With the rapid adoption of smartphones and increased Internet connectivity,SMS spam has emerged as a prevalent threat.Spammers have recognized the critical role SMS plays in today’s modern communication,making it a prime target for abuse.As cybersecurity threats continue to evolve,the volume of SMS spam has increased substantially in recent years.Moreover,the unstructured format of SMS data creates significant challenges for SMS spam detection,making it more difficult to successfully combat spam attacks.In this paper,we present an optimized and fine-tuned transformer-based Language Model to address the problem of SMS spam detection.We use a benchmark SMS spam dataset to analyze this spam detection model.Additionally,we utilize pre-processing techniques to obtain clean and noise-free data and address class imbalance problem by leveraging text augmentation techniques.The overall experiment showed that our optimized fine-tuned BERT(Bidirectional Encoder Representations from Transformers)variant model RoBERTa obtained high accuracy with 99.84%.To further enhance model transparency,we incorporate Explainable Artificial Intelligence(XAI)techniques that compute positive and negative coefficient scores,offering insight into the model’s decision-making process.Additionally,we evaluate the performance of traditional machine learning models as a baseline for comparison.This comprehensive analysis demonstrates the significant impact language models can have on addressing complex text-based challenges within the cybersecurity landscape. 展开更多
关键词 CYBERSECURITY Machine learning Large language model spam detection Text analytics Explainable AI Fine-tuning TRANSFORMER
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DaC-GANSAEBF:Divide and Conquer-Generative Adversarial Network-Squeeze and Excitation-Based Framework for Spam Email Identification
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作者 Tawfeeq Shawly Ahmed A.Alsheikhy +4 位作者 Yahia Said Shaaban M.Shaaban Husam Lahza Aws I.Abu Eid Abdulrahman Alzahrani 《Computer Modeling in Engineering & Sciences》 2025年第3期3181-3212,共32页
Email communication plays a crucial role in both personal and professional contexts;however,it is frequently compromised by the ongoing challenge of spam,which detracts from productivity and introduces considerable se... Email communication plays a crucial role in both personal and professional contexts;however,it is frequently compromised by the ongoing challenge of spam,which detracts from productivity and introduces considerable security risks.Current spam detection techniques often struggle to keep pace with the evolving tactics employed by spammers,resulting in user dissatisfaction and potential data breaches.To address this issue,we introduce the Divide and Conquer-Generative Adversarial Network Squeeze and Excitation-Based Framework(DaC-GANSAEBF),an innovative deep-learning model designed to identify spam emails.This framework incorporates cutting-edge technologies,such as Generative Adversarial Networks(GAN),Squeeze and Excitation(SAE)modules,and a newly formulated Light Dual Attention(LDA)mechanism,which effectively utilizes both global and local attention to discern intricate patterns within textual data.This approach significantly improves efficiency and accuracy by segmenting scanned email content into smaller,independently evaluated components.The model underwent training and validation using four publicly available benchmark datasets,achieving an impressive average accuracy of 98.87%,outperforming leading methods in the field.These findings underscore the resilience and scalability of DaC-GANSAEBF,positioning it as a viable solution for contemporary spam detection systems.The framework can be easily integrated into existing technologies to enhance user security and reduce the risks associated with spam. 展开更多
关键词 Email spam fraud light dual attention squeeze and excitation divide and conquer-generative adversarial network-squeeze and excitation-based framework security
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Robust image-based coordinated control for spacecraft formation flying 被引量:3
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作者 Dayong HU Xiangtian ZHAO Shijie ZHANG 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2022年第9期268-281,共14页
This paper addresses a coordinated control problem for Spacecraft Formation Flying(SFF). The distributed followers are required to track and synchronize with the leader spacecraft.By using the feature points in the tw... This paper addresses a coordinated control problem for Spacecraft Formation Flying(SFF). The distributed followers are required to track and synchronize with the leader spacecraft.By using the feature points in the two-dimensional image space, an integrated 6-degree-of-freedom dynamic model is formulated for spacecraft relative motion. Without sophisticated threedimensional reconstruction, image features are directly utilized for the controller design. The proposed image-based controller can drive the follower spacecraft in the desired configuration with respect to the leader when the real-time captured images match their reference counterparts. To improve the precision of the formation configuration, the proposed controller employs a coordinated term to reduce the relative distance errors between followers. The uncertainties in the system dynamics are handled by integrating the adaptive technique into the controller, which increases the robustness of the SFF system. The closed-loop system stability is analyzed using the Lyapunov method and algebraic graph theory. A numerical simulation for a given SFF scenario is performed to evaluate the performance of the controller. 展开更多
关键词 Algebraic graph theory Coordinated control image-based visual servoing Robust control Spacecraft formation flying
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Image-Based Brachytherapy in Cervical Cancer: Review and Experiences in Faculty of Medicine, Chiang Mai University 被引量:2
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作者 Ekkasit Tharavichitkul Somvilai Chakrabandhu +2 位作者 Pitchayaponne Klunklin Wimrak Onchan Imjai Chitapanarux 《Journal of Cancer Therapy》 2013年第5期1-7,共7页
Cervical cancer is the one of the most common cancer in female patients inThailand. Radiotherapy has the role for the treatment of cervical cancer by postoperative, radical and palliative treatments. For radical radio... Cervical cancer is the one of the most common cancer in female patients inThailand. Radiotherapy has the role for the treatment of cervical cancer by postoperative, radical and palliative treatments. For radical radiotherapy, the combination of external beam radiation therapy and brachytherapy will be used to increase the tumor dose to curative goal. With the new development of medical images (Computed tomography (CT), Magnetic Resonance Imaging (MRI) or Ultrasonography (US)), the treatment with brachytherapy will be developed from point-based to volume-based concepts. Many studies reported the benefit of image-based brachytherapy over conventional brachytherapy and clinical benefit of using image-based brachytherapy in the treatment of cervical cancer. 展开更多
关键词 image-based BRACHYTHERAPY Cervical Cancer REVIEW
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A sparse representation method for image-based surface defect detection 被引量:1
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作者 YAO Ming-hai GU Qin-long 《Optoelectronics Letters》 EI 2018年第6期476-480,共5页
In this paper, an efficient sparse representation-based method is presented for detecting surface defects. The proposed method uses the sparse degree of coefficient in the redundant dictionary for checking whether the... In this paper, an efficient sparse representation-based method is presented for detecting surface defects. The proposed method uses the sparse degree of coefficient in the redundant dictionary for checking whether the test image is defective or not, and the binary representation of the defective images is obtained, according to the global coefficient feature. Owing to the requirements for the efficiency and detecting quality, the block proximal gradient operator is introduced to speed up the online dictionary learning. Considering the correlation among the testing samples, prior knowledge is applied in the orthogonal-matching-pursuit sparse representation algorithm to improve the speed of sparse coding. Experimental results demonstrate that the proposed detection method can effectively detect and extract the defects of the surface images, and has broad applicability. 展开更多
关键词 SURFACE DEFECT detection A SPARSE REPRESENTATION METHOD image-based
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A review on image-based rendering 被引量:1
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作者 Yuan CHANG Guo-Ping WANG 《Virtual Reality & Intelligent Hardware》 2019年第1期39-54,共16页
Image-based rendering is important both in the field of computer graphics and computer vision,and it is also widely used in virtual reality technology.For more than two decades,people have done a lot of work on the re... Image-based rendering is important both in the field of computer graphics and computer vision,and it is also widely used in virtual reality technology.For more than two decades,people have done a lot of work on the research of image-based rendering,and these methods can be divided into two categories according to whether the geometric information of the scene is utilized.According to this classification,we introduce some classical methods and representative methods proposed in recent years.We also compare and analyze the basic principles,advantages and disadvantages of different methods.Finally,some suggestions are given for research directions on image-based rendering techniques in the future. 展开更多
关键词 image-based rendering Virtual reality Image interpolation PANORAMA
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Three Dimensional Microstructure and Image-Based Simulation of a Fly Ash/Al Syntactic Foam Using X-ray Micro-Computed Tomography
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作者 张强 WU Gaohui 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2013年第1期99-103,共5页
An aluminum matrix syntactic foam, incorporated with hollow-structured fly ash particles, was fabricated by pressure infiltration technique. X-ray micro-computed tomography was used to characterize its heterogeneous m... An aluminum matrix syntactic foam, incorporated with hollow-structured fly ash particles, was fabricated by pressure infiltration technique. X-ray micro-computed tomography was used to characterize its heterogeneous microstructure three dimensionally (3D). The quantification of some microstructure features, such as content and size distribution of hollow fly ash particles, was acquired in 3D. The tomographic data were exploited as a rapid method to generate a microstructurally accurate and robust 3D meshed model. The thermal transport behavior has been modeled using a commercial finite-element code to conduct steady state analyses. Simulation of the thermal conductivity showed good correlation with experimental result. 展开更多
关键词 fly ash syntactic foam TOMOGRAPHY MICROSTRUCTURE image-based simulation
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A Hierarchical Two-Level Feature Fusion Approach for SMS Spam Filtering
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作者 Hussein Alaa Al-Kabbi Mohammad-Reza Feizi-Derakhshi Saeed Pashazadeh 《Intelligent Automation & Soft Computing》 2024年第4期665-682,共18页
SMS spam poses a significant challenge to maintaining user privacy and security.Recently,spammers have employed fraudulent writing styles to bypass spam detection systems.This paper introduces a novel two-level detect... SMS spam poses a significant challenge to maintaining user privacy and security.Recently,spammers have employed fraudulent writing styles to bypass spam detection systems.This paper introduces a novel two-level detection system that utilizes deep learning techniques for effective spam identification to address the challenge of sophisticated SMS spam.The system comprises five steps,beginning with the preprocessing of SMS data.RoBERTa word embedding is then applied to convert text into a numerical format for deep learning analysis.Feature extraction is performed using a Convolutional Neural Network(CNN)for word-level analysis and a Bidirectional Long Short-Term Memory(BiLSTM)for sentence-level analysis.The two-level feature extraction enables a complete understanding of individual words and sentence structure.The novel part of the proposed approach is the Hierarchical Attention Network(HAN),which fuses and selects features at two levels through an attention mechanism.The HAN can deal with words and sentences to focus on the most pertinent aspects of messages for spam detection.This network is productive in capturing meaningful features,considering both word-level and sentence-level semantics.In the classification step,the model classifies the messages into spam and ham.This hybrid deep learning method improve the feature representation,and enhancing the model’s spam detection capabilities.By significantly reducing the incidence of SMS spam,our model contributes to a safer mobile communication environment,protecting users against potential phishing attacks and scams,and aiding in compliance with privacy and security regulations.This model’s performance was evaluated using the SMS Spam Collection Dataset from the UCI Machine Learning Repository.Cross-validation is employed to consider the dataset’s imbalanced nature,ensuring a reliable evaluation.The proposed model achieved a good accuracy of 99.48%,underscoring its efficiency in identifying SMS spam. 展开更多
关键词 SMS spam detection hierarchical attention network text classification natural language processing
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基于概念格融合模型的垃圾评论识别研究
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作者 刘伟江 马小雯 王博 《现代情报》 北大核心 2025年第4期23-35,共13页
[目的/意义]为有效解决基元学习器和集成模型对单形态特定模式的依赖和局限,本文通过加大观察粒度将分类器拓展为可适应多形态混合模式的分类器,以期提升模型理解能力和分类能力。[方法/过程]本文以概念集替代原始特征,引入互斥概念集... [目的/意义]为有效解决基元学习器和集成模型对单形态特定模式的依赖和局限,本文通过加大观察粒度将分类器拓展为可适应多形态混合模式的分类器,以期提升模型理解能力和分类能力。[方法/过程]本文以概念集替代原始特征,引入互斥概念集和正交样本集的概念,对样本进行分离、归纳和融合,构建概念格融合模型,并从模型特质、模型能力、模型品质及过拟合4个方面对模型进行评价。[结果/结论]以亚马逊23971条评论为样本集的测算结果表明,概念格融合模型在准确性、稳定性、抗干扰性等方面都有较大提升,且模型评价结果表明该模型具有更佳的内在品质。 展开更多
关键词 垃圾评论 基元学习器 集成模型 概念格 概念格融合模型
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利用SPAMS研究石家庄市冬季连续灰霾天气的污染特征及成因 被引量:66
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作者 周静博 任毅斌 +5 位作者 洪纲 路娜 李治国 李雷 李会来 靳伟 《环境科学》 EI CAS CSCD 北大核心 2015年第11期3972-3980,共9页
2014年11月18~26日石家庄市发生了连续的灰霾天气.利用位于石家庄市大气自动监测站(20 m)的单颗粒气溶胶质谱仪(SPAMS)分析了细颗粒物的化学组成,根据石家庄市大气污染物排放源谱库对主要成分进行了来源解析,并结合颗粒物质量浓度和气... 2014年11月18~26日石家庄市发生了连续的灰霾天气.利用位于石家庄市大气自动监测站(20 m)的单颗粒气溶胶质谱仪(SPAMS)分析了细颗粒物的化学组成,根据石家庄市大气污染物排放源谱库对主要成分进行了来源解析,并结合颗粒物质量浓度和气象条件研究了该地区冬季灰霾天气成因.结果表明,石家庄市大气细颗粒物来源分为7类,各源示踪离子:燃煤源为Al,工业源为OC、Fe、Pb,机动车尾气源为EC,扬尘源为Al、Ca、Si,生物质燃烧源为K和左旋葡聚糖,纯二次无机源为SO-4、NO-2和NO-3,餐饮源为HOC.灰霾期间大气中主要含有OC、HOC、EC、HEC、ECOC、富钾颗粒、矿物质和重金属等8类颗粒,其中OC和ECOC颗粒最多,分别占到总数的50%和20%以上,OC颗粒主要来自燃煤和工业工艺,ECOC颗粒主要来自燃煤和机动车尾气排放.灰霾发生时含有NH+4、SO-4、NO-2和NO-3等二次离子的颗粒物占比升高,其中含NH+4颗粒增幅最大;EC、OC与NO-3、SO-4、NH+4在灰霾天气下的混合程度均比干净天气高,其中与NH+4的混合程度加剧最为明显.冬季采暖期煤炭的大量燃烧、医化行业工艺过程及机动车尾气等污染源排放的一次气态污染物(SO2、NOx、NH3、VOCs)和一次颗粒物在静稳天气中难以扩散而迅速累积,气态污染物发生二次转化形成硝酸铵、硫酸铵,而颗粒物之间通过碰撞形成二次颗粒物并发生不同程度的混合,从而导致大气能见度下降,以上是石家庄市冬季灰霾形成的主要原因. 展开更多
关键词 灰霾 细颗粒物 污染特征 成因 spamS 石家庄市
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清代滥发官文书研究
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作者 赵彦昌 王艺潭 《档案学刊》 2025年第5期83-93,108,共12页
清代官文书作为历史遗留的宝贵史料,是传递与记录政情、民情的重要依据。清代滥发官文书行为主要分为两类:以虚假手段发送官文书和滥用职权发送官文书。由于清代官文书所包含的文书种类的范围较广,因此涉及不同文种的滥发情况。同样,这... 清代官文书作为历史遗留的宝贵史料,是传递与记录政情、民情的重要依据。清代滥发官文书行为主要分为两类:以虚假手段发送官文书和滥用职权发送官文书。由于清代官文书所包含的文书种类的范围较广,因此涉及不同文种的滥发情况。同样,这也导致清代滥发官文书的行为涉及各个不同的事务领域,这类行为不仅破坏了官文书的权威性,而且干扰了清代行政秩序。 展开更多
关键词 清代 滥发官文书 官文书 牌票
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利用SPAMS构建石家庄市PM_(2.5)固定排放源成分谱库 被引量:24
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作者 周静博 张涛 +3 位作者 李治国 路娜 王耀涛 靳伟 《河北工业科技》 CAS 2015年第5期443-450,共8页
依托单颗粒气溶胶质谱仪(SPAMS),选取石家庄市燃煤、工业工艺、固废焚烧等固定排放源的典型企业展开了PM2.5固定排放源谱库的建立工作。通过对选取的有代表性的源排放样品进行采集和分析,获取了各排放源颗粒物的典型质谱信息和粒径分... 依托单颗粒气溶胶质谱仪(SPAMS),选取石家庄市燃煤、工业工艺、固废焚烧等固定排放源的典型企业展开了PM2.5固定排放源谱库的建立工作。通过对选取的有代表性的源排放样品进行采集和分析,获取了各排放源颗粒物的典型质谱信息和粒径分布特征。结果显示,三类污染源排放的颗粒物粒径峰值基本出现在1.0~1.5μm处;电力、水泥、制药、生活垃圾和危险废物焚烧行业排放的颗粒物粒径分布较窄,在0~3.0μm,而钢铁和医疗废物焚烧行业排放的颗粒物粒径范围较宽,在0~6.0μm左右;燃煤源的特征组分为Cr、有机低聚物、有机物和ECOC;工业工艺源的特征组分为OC,Fe,Pb,CaO,硅酸盐,有机胺;固废焚烧源的特征组分为元素碳、Pb、有机胺、Na,NaCl。该研究建立的石家庄市PM2.5固定排放源谱库,为石家庄市大气中PM2.5的在线来源解析提供了有效准确的识别依据。 展开更多
关键词 大气污染防治工程 排放源 spamS 谱库 PM2.5 石家庄市
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利用SPAMS研究华北乡村站点(曲周)夏季大气单颗粒物老化与混合状态 被引量:19
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作者 黄子龙 曾立民 +2 位作者 董华斌 李梅 朱彤 《环境科学》 EI CAS CSCD 北大核心 2016年第4期1188-1198,共11页
利用单颗粒气溶胶飞行时间质谱(SPAMS)于2013年6月30日-7月8日对华北地区乡村站点曲周大气单颗粒粒径及其化学组成进行了在线测量,共采集到同时含有正负离子谱图的颗粒230 152个,其粒径主要集中在0.2-2.0μm.结果表明,该地区的大气颗... 利用单颗粒气溶胶飞行时间质谱(SPAMS)于2013年6月30日-7月8日对华北地区乡村站点曲周大气单颗粒粒径及其化学组成进行了在线测量,共采集到同时含有正负离子谱图的颗粒230 152个,其粒径主要集中在0.2-2.0μm.结果表明,该地区的大气颗粒物主要分为8类:元素碳(EC,55.5%)、有机碳(OC,10.7%)、钠,钾等碱金属颗粒(alkalis,17.4%)、其他金属颗粒(other metals,1.7%)、富铁颗粒(Fe-rich,6.3%)、富铅颗粒物(Pb-rich,3.1%)、沙尘颗粒(dust,4.8%),other颗粒(0.8%),观测得到的8类气溶胶颗粒中绝大部分包含^46NO2^-、^62NO3^-、^80SO3^-、^96SO4^-、^97HSO4^-等二次组分离子,说明这些颗粒都经历了不同的老化过程或与二次组分进行了不同程度的混合.从气溶胶类型的谱分布看,各类型颗粒数浓度峰值基本出现在700-800 nm之间,dust、Fe颗粒主要集中在粗粒径段,EC颗粒子类研究表明随着表面不断吸附NH4^+、NO^3-、SO4^2-等二次组分,EC颗粒逐步演化成老化程度较低的NO^3-吸附型EC(ECN)和严重老化的SO4^2-吸附型EC(ECS)混合态,两者日变化呈现明显的负相关性,也可能随着二次有机物在EC表面吸附,形成OC/EC混合态. 展开更多
关键词 单颗粒 化学组成 粒径 混合状态 单颗粒气溶胶飞行时间质谱(spamS)
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利用SPAMS初探盘锦市冬季PM2.5污染特征及来源 被引量:8
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作者 邰姗姗 仇伟光 +3 位作者 张青新 祖彪 陈宗娇 王德羿 《中国环境监测》 CAS CSCD 北大核心 2017年第3期147-153,共7页
利用SPAMS 0515于2015年1月在盘锦市兴隆台空气质量自动监测点位采集PM2.5样品,并分析其污染特征和来源。研究结果表明,盘锦市冬季PM2.5的颗粒类型主要以OC颗粒、富钾颗粒、EC颗粒组成。其中,OC颗粒占比最高,为52.5%;PM2.5污染的主要贡... 利用SPAMS 0515于2015年1月在盘锦市兴隆台空气质量自动监测点位采集PM2.5样品,并分析其污染特征和来源。研究结果表明,盘锦市冬季PM2.5的颗粒类型主要以OC颗粒、富钾颗粒、EC颗粒组成。其中,OC颗粒占比最高,为52.5%;PM2.5污染的主要贡献源为燃煤、生物质燃烧、机动车尾气排放,占比分别为33.2%、25.7%、17.5%,特别是在PM2.5质量浓度较高时段,燃煤和机动车尾气排放对污染的贡献较大。 展开更多
关键词 细颗粒物 spamS 污染特征 来源 盘锦市
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Co-Training——内容和链接的Web Spam检测方法 被引量:4
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作者 魏小娟 李翠平 陈红 《计算机科学与探索》 CSCD 2010年第10期899-908,共10页
Web spam是指通过内容作弊和网页间链接作弊来欺骗搜索引擎,从而提升自身搜索排名的作弊网页,它干扰了搜索结果的准确性和相关性。提出基于Co-Training模型的Web spam检测方法,使用了网页的两组相互独立的特征——基于内容的统计特征和... Web spam是指通过内容作弊和网页间链接作弊来欺骗搜索引擎,从而提升自身搜索排名的作弊网页,它干扰了搜索结果的准确性和相关性。提出基于Co-Training模型的Web spam检测方法,使用了网页的两组相互独立的特征——基于内容的统计特征和基于网络图的链接特征,分别建立两个独立的基本分类器;使用Co-Training半监督式学习算法,借助大量未标记数据来改善分类器质量。在WEB SPAM-UK2007数据集上的实验证明:算法改善了SVM分类器的效果。 展开更多
关键词 WEB spam检测方法 内容作弊 链接作弊 Co—Training算法
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一种随机嵌入抗SPAM检测的可逆数据隐藏算法 被引量:5
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作者 柳玲 陈同孝 +1 位作者 曹晨 陈玉明 《计算机应用研究》 CSCD 北大核心 2013年第7期2111-2114,共4页
针对数据隐藏算法在携带信息时容易被检测工具SPAM侦测出来这一现象,将随机嵌入和直方图修正技术应用到数据隐藏中,提出一种随机嵌入抗SPAM检测的可逆数据隐藏算法。该方法通过对采样子图与参照子图间的差值直方图进行平移空位来嵌入信... 针对数据隐藏算法在携带信息时容易被检测工具SPAM侦测出来这一现象,将随机嵌入和直方图修正技术应用到数据隐藏中,提出一种随机嵌入抗SPAM检测的可逆数据隐藏算法。该方法通过对采样子图与参照子图间的差值直方图进行平移空位来嵌入信息。在信息嵌入过程中,用随机函数产生的伪随机序列来标志待隐藏信息的位置,使嵌入的信息分布更不规律,从而更好地逃脱检测工具SPAM的侦测。实验结果表明,相比Kim算法,该算法抗SPAM检测的安全性更好,更适合进行信息传递。 展开更多
关键词 随机嵌入 spam 可逆数据隐藏 直方图修正 子图采样
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在线社交网络中Spam相册检测方案 被引量:1
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作者 吕少卿 张玉清 +1 位作者 刘东航 张光华 《通信学报》 EI CSCD 北大核心 2016年第9期82-91,共10页
提出一种针对Spam相册的检测方案。首先分析了Photo Spam的攻击特点以及与传统Spam的差异,在此基础上构造了12个提取及时且计算高效的特征。利用这些特征提出了有监督学习的检测模型,通过2 356个相册的训练形成Spam相册分类器,实验表明... 提出一种针对Spam相册的检测方案。首先分析了Photo Spam的攻击特点以及与传统Spam的差异,在此基础上构造了12个提取及时且计算高效的特征。利用这些特征提出了有监督学习的检测模型,通过2 356个相册的训练形成Spam相册分类器,实验表明能够正确检测到测试集中100%的Spam相册和98.2%的正常相册。最后将训练后的模型应用到包含315 115个相册的真实数据集中,检测到89 163个Spam相册,正确率达到97.2%。 展开更多
关键词 社交网络安全 PHOTO spam spam检测 人人网
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SPAMS打击率影响因素与仪器状态分析 被引量:2
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作者 王莉华 刘保献 +3 位作者 张大伟 张人太 安欣欣 魏强 《质谱学报》 EI CAS CSCD 北大核心 2018年第1期36-45,共10页
在北京市环境保护监测中心空气质量综合观测实验室,使用气溶胶单颗粒飞行时间质谱(SPAMS)对2013年1~12月空气颗粒物开展综合观测。实验结果表明,SPAMS打击率与测径颗粒数(siz)、大气相对湿度、颗粒物组分以及粒径有关。仪器状态正常时,... 在北京市环境保护监测中心空气质量综合观测实验室,使用气溶胶单颗粒飞行时间质谱(SPAMS)对2013年1~12月空气颗粒物开展综合观测。实验结果表明,SPAMS打击率与测径颗粒数(siz)、大气相对湿度、颗粒物组分以及粒径有关。仪器状态正常时,打击率在siz数量小、大气相对湿度低时较高,与含K^+、HSO_4^-、OCEC、NO_3^-的颗粒物以及粒径为0.2~0.3μm、0.3~0.4μm、0.4~0.5μm的颗粒物数量呈正相关,与0.1~0.2μm、0.5~0.6μm、0.6~0.7μm的颗粒物数量呈负相关,含NH_4^+、SiO_3^-颗粒物数量的关系与污染特征及其他环境有关。本研究通过分析打击率数值及打击率与各影响因素的关系判断仪器状态是否正常,这为提前发现常规方法难以发现的仪器故障提供了一种思路。 展开更多
关键词 PM25 单颗粒气溶胶飞行时间质谱(spamS) 打击率 仪器故障
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利用SPAMS研究上海秋季气溶胶污染过程中颗粒物的老化与混合状态 被引量:55
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作者 牟莹莹 楼晟荣 +10 位作者 陈长虹 周敏 王红丽 周振 乔利平 黄成 李梅 李莉 王倩 黄海英 邹兰军 《环境科学》 EI CAS CSCD 北大核心 2013年第6期2071-2080,共10页
利用单颗粒气溶胶飞行时间质谱(SPAMS)于2011年11月11~18日在上海测量了气溶胶高污染过程中200 nm~2.0μm气溶胶的粒径谱及其化学组成.对气溶胶粒子的分类结果发现,灰霾天期间大气中主要存在OCEC、METAL、EC、SECONDARY和K-Na等5种气... 利用单颗粒气溶胶飞行时间质谱(SPAMS)于2011年11月11~18日在上海测量了气溶胶高污染过程中200 nm~2.0μm气溶胶的粒径谱及其化学组成.对气溶胶粒子的分类结果发现,灰霾天期间大气中主要存在OCEC、METAL、EC、SECONDARY和K-Na等5种气溶胶粒子,其粒子数分别占总数的27.4%、3.4%、7.3%、45.6%和5.4%,二次污染显著.观测得到的5类气溶胶颗粒中都包含18NH4+、80SO3-、96SO4-、97HSO4-、46NO2-、62NO3-、125H(NO3)2-等二次组分,说明灰霾天期间这些颗粒都经历了不同的二次过程或与二次组分进行了不同程度的混合,且随着灰霾的生成和发展,气溶胶不断老化,二次气溶胶粒子的信号迅速增强.OCEC粒子中97HSO4-的信号较强,说明SO2可能在气溶胶表面发生多相反应,同时因有机物的存在对气态硫酸参与气溶胶成核和增长起了重要作用,尤其是在严重污染的条件下,气态硫酸和有机蒸气相互作用可能加速了硫酸-有机颗粒物的形成.从气溶胶类型的谱分布可以发现,新鲜的EC气溶胶粒子排入大气后,其表面会不断附着18NH+4、80SO3-、96SO4-、97HSO4-、46NO2-、62NO3-、125H(NO3)2-等二次组分,EC颗粒在老化的过程中其类型逐步由EC气溶胶演变成二次气溶胶粒子.来自海洋的暖湿气流除了形成降水对气溶胶形成冲刷作用,使得二次气溶胶粒子和OCEC气溶胶粒子数明显降低以外,也将有机胺带入内陆,在清洁天气溶胶粒子中形成Amine粒子. 展开更多
关键词 灰霾 单颗粒 化学组成 混合状态 单颗粒气溶胶飞行时间质谱
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