期刊文献+
共找到795篇文章
< 1 2 40 >
每页显示 20 50 100
Urban and rural transport of semivolatile organic compounds at regional scale: A multimedia model approach 被引量:9
1
作者 Shuai Song Chao Su +3 位作者 Yonglong Lu Tieyu Wang Yueqing Zhang Shijie Liu 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2016年第1期228-241,共14页
Urban areas are generally regarded as major sources of some semivolatile organic compounds and other persistent organic pollutants(POPs) to the surrounding regions. Huge differences in contaminant emissions between ... Urban areas are generally regarded as major sources of some semivolatile organic compounds and other persistent organic pollutants(POPs) to the surrounding regions. Huge differences in contaminant emissions between urban and rural areas directly affect their fate in environmental media. Little is known about POPs behavior between urban and rural areas at a regional scale. A spatially resolved Berkeley-Trent-Urban-Rural Fate Model(BETR-UR) was designed by coupling land cover information to simulate the transport of POPs between urban and rural areas, and the Bohai Rim was used as a case study to estimate Polycyclic Aromatic Hydrocarbon(PAH) fate. The processes of contaminant fate including emission, inter-compartmental transfer, advection and degradation in urban and rural areas were simulated in the model. Simulated PAH concentrations in environmental media of urban and rural areas were very close to measured values. The model accuracy was highly improved, with the average absolute relative error for PAH concentrations reduced from 37% to 3% compared with unimproved model results. PAH concentrations in urban soil and air were considerably higher than those in rural areas. Sensitivity analysis showed temperature was the most influential parameter for Phen rather than for Bap, whose fate was more influenced by emission rate, compartment dimension, transport velocity and chemical persistence. Uncertainty analysis indicated modeled results in urban media had higher uncertainty than those in rural areas due to larger variations of emissions in urban areas. The differences in urban and rural areas provided us with valuable guidance on policy setting for urban–rural POP control. 展开更多
关键词 Land use PAH fate Regional scale multimedia model
原文传递
An enhanced environmental multimedia modeling system based on fuzzy-set approach: II. Model validation and application
2
作者 Rongrong ZHANG Chesheng ZHAN +1 位作者 Xiaomeng SONG Baolin LIU 《Frontiers of Environmental Science & Engineering》 SCIE EI CAS CSCD 2015年第6期1025-1035,共11页
Part I of this study develops an enhanced environmental multimedia modeling system (EMMS) based on fuzzy-set approach. Once the model development is complete, the composite module and the entire modeling system need... Part I of this study develops an enhanced environmental multimedia modeling system (EMMS) based on fuzzy-set approach. Once the model development is complete, the composite module and the entire modeling system need to be tested and validated to ensure that the model can simulate natural phenomena with reasonable and reliable accuracy. The developed EMMS is first tested in a complete case study. And then verification results are conducted to compare with extensively researched litera- ture data. In the third step, the data from an experimental landfill site is used for a pilot-scale validation. The comparisons between EMMS outputs and the literature data indicate that the EMMS can perform accurate modeling simulation. The modules of EMMS could support the entire environmental multimedia modeling system. Further field-scale validation is finished. The results are satisfactory. Most of the modeling yields closely match the monitoring data collected from sites. In addition, with the aid of fuzzy-set approach, EMMS can be a reliable and powerful tool to address the complex environmental multimedia pollution problems and provide an extensive support for decision makers in managing the contaminated environmental systems. 展开更多
关键词 environmental multimedia modelling system fuzzy-set approach APPLICATION model validation uncer-tainty analysis
原文传递
An enhanced environmental multimedia modeling system based on fuzzy-set approach: I. Theoretical framework and model development
3
作者 Chesheng ZHAN Rongrong ZHANG +1 位作者 Xiaomeng SONG Baolin LIU 《Frontiers of Environmental Science & Engineering》 SCIE EI CAS CSCD 2015年第3期494-505,共12页
Multimedia environmental modeling is extremely complex due to the intricacy of the systems with the consideration of many related factors. Traditional environmental multimedia models (EMMs) are usually based on one-... Multimedia environmental modeling is extremely complex due to the intricacy of the systems with the consideration of many related factors. Traditional environmental multimedia models (EMMs) are usually based on one-dimensional and first-order assumptions, which may cause numerical errors in the simulation results. In this study, a new user-friendly fuzzy-set enhanced environmental multimedia modeling system (FEEMMS) is developed, and includes four key modules: an air dispersion module, a polluting source module, an unsaturated zone module, and a groundwater module. Many improvements over previous EMMs have been achieved through dynamically quantifying the intermedia mass flux; incorporating fuzzy-set approach into environmental multimedia modeling system (EMMS); and designing a user-friendly graphic user interface (GUI). The developed FEEMMS can be a useful tool in estimating the timevarying and spatial-varying chemical concentrations in air, soil, and groundwater; characterizing the potential risk to human health presented by contaminants released from a contaminated site; and quantifying the uncertainties associated with modeling systems and subsequently providing robustness and flexibility for the remediationrelated decision making. 展开更多
关键词 environmental multimedia modelling fuzzyset approach theoretical framework environmental protection
原文传递
Interactive Multimedia Synchronization Model Based on Petri Nets 被引量:2
4
作者 WANG Zhiqiang PENG Xiaogang JI Zhen 《Wuhan University Journal of Natural Sciences》 CAS 2007年第6期1019-1023,共5页
The multimedia synchronization is used to coordinate the timing of each multimedia object in the multimedia system. After studying different multimedia synchronization systems that have been published, an Interactive ... The multimedia synchronization is used to coordinate the timing of each multimedia object in the multimedia system. After studying different multimedia synchronization systems that have been published, an Interactive Synchronization multimedia based on Petri Nets model (ISPN) is proposed in this paper. The system is capable of describing the dynamic timing actions of multimedia objects vividly as well as controlling them interactively to maintain the system level synchronization balance. 展开更多
关键词 Petri net multimedia synchronization model ISPN
在线阅读 下载PDF
Novel encryption model for multimedia data 被引量:1
5
作者 Ye Dengpan~(1,2) & Lian Shiguo~3 1.The Key Laboratory of Aerospace Information Security and Trust Computing,Ministry of Education,Wuhan 430072,P.R.China 2.School of Computer Science,Wuhan Univ.,Wuhan 430072,P.R.China 3.France Telecom R&D Beijing,Beijing 100080,P.R.China 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2009年第5期1081-1085,共5页
A novel encryption model is proposed. It combines encryption process with compression process, and realizes compression and encryption at the same time. The model's feasibility and security are analyzed in detail. An... A novel encryption model is proposed. It combines encryption process with compression process, and realizes compression and encryption at the same time. The model's feasibility and security are analyzed in detail. And the relationship between its security and compression ratio is also analyzed. 展开更多
关键词 multimedia encryption model compression FEASIBILITY security.
在线阅读 下载PDF
DATA MODEL FOR MULTIMEDIA DATABASE SYSTEM NHMDB BASED ON NF^2 DATA MODEL
6
作者 Guo Hongying Lin Junhai Tian Canghai (Department of Comprter Science and Engineering ,NUAA 29 Yudao Street,Nanjing 210016,P.R.China) 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 1994年第2期210-214,共5页
An approach to implementing the multimedia database system NHMDB based on NF2(Non-First-Normal-Form) data model is presented. This approach is easily implemented because NF2 structure can efficiently store various med... An approach to implementing the multimedia database system NHMDB based on NF2(Non-First-Normal-Form) data model is presented. This approach is easily implemented because NF2 structure can efficiently store various media data such as formatted data, text,graphics, image and voice. The main idea is to expand conceptual schema to maintain the consistency of tbreelevel schema in system NHMDB. We developed, implemented and experimented the storage structure and the multimedia data representation by an object identifier.implementation techniques are also discussed. 展开更多
关键词 DATABASE APPROXIMATION DATA model multimedia
在线阅读 下载PDF
Temporal Models for Multimedia Synchronization
7
作者 李明禄 《High Technology Letters》 EI CAS 1997年第2期37-41,共5页
This paper provides a survey of selection of most common existing temporal models for multimedia synchronization, which are based on CSP, CCS, path expressions, and Petri net. Multimedia refers to the integrated gener... This paper provides a survey of selection of most common existing temporal models for multimedia synchronization, which are based on CSP, CCS, path expressions, and Petri net. Multimedia refers to the integrated generation, representation, processing, storage, and dissemination of information expressed in multiple time dependent and time independent media such as data, text, graphics, images, audio, and video. Synchronization assures a temporal order of events, which is a well-studied topic in the area of operating systems, parallel programming languages, and database technology. 展开更多
关键词 multimedia SYNCHRONIZATION TEMPORAL modelS CONCURRENT THEORY
在线阅读 下载PDF
QoE Modeling and Applications for Multimedia Systems
8
作者 Wenjun Zeng Weisi Lin 《ZTE Communications》 2013年第1期1-1,共1页
Ireproving the quality and experience perceived by the user is fundamental when de- veloping multimedia technologies, products, and services. Quality of experience (QoE) involves subjective perception, user behavior... Ireproving the quality and experience perceived by the user is fundamental when de- veloping multimedia technologies, products, and services. Quality of experience (QoE) involves subjective perception, user behavior and needs, appropriateness, con- text, and usability of delivered content. Modeling QoE is critical for enhancing QoE in various nmhimedia applications. In this special issue, 展开更多
关键词 QoE modeling and Applications for multimedia Systems DTV
在线阅读 下载PDF
基于深度强化学习的计算机多媒体图像分类技术研究
9
作者 陈伟 《移动信息》 2025年第4期314-316,共3页
文中深入探索了基于深度强化学习的计算机多媒体图像分类技术。首先,阐述了深度强化学习原理,包括智能体、环境、状态、动作和奖励机制,及深度神经网络在逼近价值函数或策略函数的应用。其次,介绍了多媒体图像颜色、纹理、形状特征提取... 文中深入探索了基于深度强化学习的计算机多媒体图像分类技术。首先,阐述了深度强化学习原理,包括智能体、环境、状态、动作和奖励机制,及深度神经网络在逼近价值函数或策略函数的应用。其次,介绍了多媒体图像颜色、纹理、形状特征提取方法和卷积神经网络在其中的作用。同时,详细描述了模型整体架构,含卷积神经网络感知模块和包括策略网络、价值网络的决策模块,以及奖励机制设计。最后,从训练数据集准备、训练参数设置和利用强化学习策略优化训练3个方面阐述了模型训练与优化过程,为多媒体图像分类提供了全面的技术方案。 展开更多
关键词 深度强化学习 多媒体图像 图像分类 模型构建
在线阅读 下载PDF
Source emissions and climate change impacts on the multimedia transport and fate of persistent organic pollutants,Chaohu watershed,eastern China 被引量:3
10
作者 Xianghui Cao Shouliang Huo +4 位作者 Hanxiao Zhang Jiaqi Zheng Zhuoshi He Chunzi Ma Shuai Song 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2021年第11期15-25,共11页
Emission intensity and climate change control the transport flux and fate of persistent organic pollutants(POPs)inmultiple environmental compartments.This study applied amultimedia model(BETR model)to explore alternat... Emission intensity and climate change control the transport flux and fate of persistent organic pollutants(POPs)inmultiple environmental compartments.This study applied amultimedia model(BETR model)to explore alternations in the spatio-temporal trends of concentrations and transport flux of benzopyrene(BaP),phenanthrene(Phe),perfluorooctane sulfonates(PFOS)and polychlorinated biphenyls(PCBs)in the Chaohu watershed,located in the lower reaches of the Yangtze River,China in response to changes in source emissions and climate.The potential historic and future risks of these pollutants also were assessed.The results suggest that current trends in concentrations and transport were similar to that of their emissions between 2005 and 2018.During the next 100 years,temporal trends and spatial patterns were not predicted to change significantly,which is consistent with climate change.Based on sensitivity and correlation analyses,climate change had significant effects on multi-media concentrations and transport fluxes of BaP,Phe,PFOS and PCBs,and rainfall intensity was the predominant controlling factor.Risk quotients(RQs)of BaP and Phe-in soil increased from 0.42 to 0.95 and 0.06 to 0.35,respectively,from 2005 to 2090,indicating potential risks.The RQs of the other examined contaminants exhibited little potential risk in soil,water,or sediment.Based on spatial patterns,it was inferred that the ecosystem around Lake Chaohu is the most at risk.The study provides insights needed for local pollution control of POPs in the Chaohu watershed.In addition,the developed approach can be applied to other watersheds world-wide. 展开更多
关键词 Climate change POP emissions multimedia model Contaminant transport Risk assessment
原文传递
基于LLM的多媒体原生库模糊测试研究
11
作者 解梦飞 傅建明 姚人懿 《信息网络安全》 北大核心 2025年第3期403-414,共12页
多媒体原生库通过C/C++语言直接操作底层系统资源,在显著提升音视频数据处理效率的同时,也引入了持久的内存安全威胁。然而,现有的原生库模糊测试研究不仅缺乏对多媒体库的针对性,还难以实现对闭源二进制程序的运行时监控机制。文章提... 多媒体原生库通过C/C++语言直接操作底层系统资源,在显著提升音视频数据处理效率的同时,也引入了持久的内存安全威胁。然而,现有的原生库模糊测试研究不仅缺乏对多媒体库的针对性,还难以实现对闭源二进制程序的运行时监控机制。文章提出一种基于LLM的多媒体原生库模糊测试方案MediaFuzzer,通过自启发式的LLM问询方案,MediaFuzzer能够准确提取蕴含在函数签名中的功能语义信息,并进一步筛选出潜在的多媒体原生库函数作为执行入口。随后,MediaFuzzer设计并实现了基于模拟执行的模糊测试框架,能够在系统依赖、内存管控和代码执行3个层次构建完整的运行时监控机制,从而实现覆盖率导向的输入变异以及主动捕获内存异常行为。实验结果表明,MediaFuzzer从500个移动应用中识别出7类共1557个多媒体函数,成功挖掘到WhatsApp中的1个已公开漏洞以及包括微信在内的3个零日漏洞。 展开更多
关键词 多媒体原生库 模糊测试 内存安全 大语言模型
在线阅读 下载PDF
以信息技术为支撑的阅读推广模式研究
12
作者 吴扬凯 《科技资讯》 2025年第5期241-243,共3页
在互联网、移动通信、人工智能等信息技术飞速发展的背景下,传统阅读方式正经历着一场深刻的变革。数字化阅读渐成主流,电子书、在线阅读平台、社交媒体等新兴工具给人们带来了大量的阅读资源与便利的阅读方式。然而,信息技术在给人们... 在互联网、移动通信、人工智能等信息技术飞速发展的背景下,传统阅读方式正经历着一场深刻的变革。数字化阅读渐成主流,电子书、在线阅读平台、社交媒体等新兴工具给人们带来了大量的阅读资源与便利的阅读方式。然而,信息技术在给人们阅读带来便利的同时,也造成注意力不集中和阅读深度不够的现象。所以,研究如何运用信息技术手段有效地开展阅读推广来激发读者阅读兴趣、促进阅读能力的培养具有十分重要的意义。首先分析信息技术环境与特点,其次分析以信息技术为支撑的阅读推广模式和案例,最后探讨信息技术驱动下高校图书馆阅读推广模式创新保障机制,希望可以进一步促进信息技术为支撑的阅读推广模式进一步发展,为相关的研究工作提供一定的参考建议。 展开更多
关键词 信息技术 阅读 推广模式 多媒体技术 云服务
在线阅读 下载PDF
基于IV级逸度模型的典型抗生素多介质环境归趋研究
13
作者 武亚林 徐井旭 +2 位作者 凌文翠 孙长虹 刘桂中 《中国环境科学》 北大核心 2025年第9期5204-5212,共9页
逸度模型是应用较为广泛的有机污染物多介质环境归趋模型,基于IV级逸度模型,本研究模拟研究了再生水补水河流凉水河中典型抗生素(氧氟沙星和罗红霉素)多介质环境归趋行为,验证了模拟可靠性,分析了平衡时迁移通量,确定了主要迁移过程,并... 逸度模型是应用较为广泛的有机污染物多介质环境归趋模型,基于IV级逸度模型,本研究模拟研究了再生水补水河流凉水河中典型抗生素(氧氟沙星和罗红霉素)多介质环境归趋行为,验证了模拟可靠性,分析了平衡时迁移通量,确定了主要迁移过程,并进行了模型关键参数灵敏度分析和不确定性分析.结果表明,模型模拟浓度与实测浓度吻合程度较高,表明模型在该研究区域的模拟有效性;研究区域内环境系统达到平衡时,水相中抗生素主要输出过程为平流过程,沉积物相主要过程是与水相的界面交换过程;平衡时氧氟沙星和罗红霉素在水和沉积物中的含量占比分别是8.73%和91.27%,27.46%和72.54%,可见沉积物是两种抗生素的主要储库;亨利定律常数H是影响两相迁移的主要因素.该研究为再生水补给型河流抗生素的环境预测与污染治理提供理论依据及决策参考. 展开更多
关键词 逸度模型 抗生素 凉水河 多介质环境归趋
在线阅读 下载PDF
基于逸度模型的渭河甘肃段典型PPCPs多介质归趋研究
14
作者 吴家庆 安锡鼎 +3 位作者 庞燕 陶艳茹 余小梅 黄天寅 《环境工程技术学报》 北大核心 2025年第4期1201-1210,共10页
揭示新污染物在环境中的归趋,能够阐明其在环境多介质中的迁移转化与累积规律,为精准评估生态与健康风险及制定靶向管控策略提供科学依据。以渭河甘肃段为研究对象,通过构建的Ⅲ级多介质逸度模型,结合现场采样分析,研究克林霉素(CLD)、... 揭示新污染物在环境中的归趋,能够阐明其在环境多介质中的迁移转化与累积规律,为精准评估生态与健康风险及制定靶向管控策略提供科学依据。以渭河甘肃段为研究对象,通过构建的Ⅲ级多介质逸度模型,结合现场采样分析,研究克林霉素(CLD)、避蚊胺(DEET)、罗红霉素(ROX)及甲氧嘧啶(TMP)4种典型药品与个人护理品(PPCPs)在渭河甘肃段环境多介质(水、悬浮物及沉积物)中的分布及迁移规律,模拟典型PPCPs的多介质归趋,结合灵敏度分析及不确定分析方法,量化模型预测的可靠性并识别关键影响参数。结果表明:1)4种PPCPs浓度的模拟值与实测值相差均在1个数量级内,构建的Ⅲ级逸度模型准确性较好;2)通过模型计算得到环境介质间主要的迁移过程为平流作用及降解作用。平流是水相PPCPs的主要输入及去除途径,水体向悬浮物的扩散及悬浮物向沉积物的沉降是悬浮物和沉积物中PPCPs主要输入途径。DEET更倾向于在悬浮物中降解且更易由沉积物向水体扩散,CLD及ROX较其他2种PPCPs更倾向于自悬浮物向沉积物沉降,TMP在悬浮物及沉积物中均主要依靠降解作用去除。3)灵敏度研究结果显示,污染物输入浓度、有机碳分配系数、水相平流输入及输出、温度、悬浮物及沉积物中有机碳含量对模型输出结果有较大影响。不确定分析则表明,模型参数整体的变化对水体输出结果影响较小,对悬浮物及沉积物影响较大。4)模型情景模拟结果显示,减少研究区域PPCPs排放并结合泥沙治理减少悬浮物含量是降低区域PPCPs污染负荷的有效策略。 展开更多
关键词 渭河甘肃段 逸度模型 药品与个人护理品(PPCPs) 多介质迁移和归趋
在线阅读 下载PDF
CAPABILITIES OF MULTIMEDIA GIS 被引量:2
15
作者 郑扣根 潘云鹤 《Chinese Geographical Science》 SCIE CSCD 1999年第2期63-69,共7页
A geographical information system (GIS) is used to capture, store, retrieve, analyzed and display the spatial (locationally defined) data. In contrast to traditional GIS, multimedia GIS is not only able to collect, an... A geographical information system (GIS) is used to capture, store, retrieve, analyzed and display the spatial (locationally defined) data. In contrast to traditional GIS, multimedia GIS is not only able to collect, analyze and store the data in traditional formats i.e. text, images (pictures) and graphs but also audio (sound), animations and video (moving pictures) as well. In this paper the advantages of multimedia GIS over traditional GIS are explained. Multimedia GIS is fully capable of providing services to both technical and non technical users and users of multimedia GIS can retain more knowledge than users of traditional GIS. It can be applied to various fields such as tourism, environment, education etc. Some implementation issues such as data updating, information retrieval and data compression etc. are also addressed. Finally, future development of MMGIS (using new multimedia technologies such as Virtual Reality and Virtual Reality Modeling Language) is discussed. 展开更多
关键词 GIS multimedia GIS multimedia DATABASE VIRTUAL REALITY VIRTUAL REALITY modeling LANGUAGE
在线阅读 下载PDF
Quality Requirements for Multimedia Interactive Informative Systems
16
作者 Sylviane Levy Fernando Gamboa 《Journal of Software Engineering and Applications》 2013年第8期416-425,共10页
Multimedia Interactive Informative Systems (MIIS) are software applications resulting from the convergence of multiples technologies such as audiovisual, computing and communication. They aim to transmit information t... Multimedia Interactive Informative Systems (MIIS) are software applications resulting from the convergence of multiples technologies such as audiovisual, computing and communication. They aim to transmit information to a large, diverse and dispersed public. As with other mass media, the fulfillment of MIIS goals depends largely on the quality of communication between the system and end users. Therefore, those systems should be developed in order to ensure that this quality requirement is satisfied. If MIIS are constructed according to usual software engineering practices, the analysis discipline of the development process includes requirements identification and specification;however, these techniques are focused on functional requirements, and they do not give much importance to non-functional requirements. In this paper, we propose a development process based on the production of videogames which has two different phases: preproduction and production. The first phase, corresponding to requirements identification, derives into the concept of system. In order to translate this concept into a specification, we propose the use of new communicational attributes and a MIIS metamodel. The establishment of MIIS non-functional specification is the result of analyzing class diagrams through quality attributes. In order to evaluate if the specifications are responding to communicational attributes, a functional prototype is built and evaluated with end users. The proposed methodology is applied to a real case study. 展开更多
关键词 multimedia INTERACTIVE INFORMATIVE SYSTEMS multimedia QUALITY model in Use QUALITY Requirements METAmodelING
在线阅读 下载PDF
Multimedia Technology for Monitoring Dispatching and Production Commanding System
17
作者 于洪珍 刘富强 陈力军 《International Journal of Mining Science and Technology》 SCIE EI 1998年第1期15-19,共5页
This paper describes the multimedia technology applied to the safety monitoring, management dispatching and production commanding system in the coal mine, analyzes and studies the methods of compression hased on model... This paper describes the multimedia technology applied to the safety monitoring, management dispatching and production commanding system in the coal mine, analyzes and studies the methods of compression hased on model data. In the system a multimedia computer is used to control a subsystem of safety monitoring, a subsystem of attendance management. and a subsystem of industrial TV. The multimedia computer will process the information of graphs. texts, sounds, pictures and images etc. It has the functions of real-time monitoring, emergency rescuing and accident analyzing. 展开更多
关键词 multimedia technology safety MONITORING DISPATCH model-BASED
在线阅读 下载PDF
Nondeterministic Temporal Relations in Multimedia Data
18
作者 李明禄 《High Technology Letters》 EI CAS 1996年第2期59-63,共5页
Synchronization is a important issue in multimedia systems which integrate a variety oftemporally related media objects.One part of synchronization is the representation of tempo-ral information.With the emerging inte... Synchronization is a important issue in multimedia systems which integrate a variety oftemporally related media objects.One part of synchronization is the representation of tempo-ral information.With the emerging interaetive multimedia,deterministic temporal modelsare replaced by nondeterministic ones with more expressiveness.This paper classifies tempo-ral models by their expressiveness,and evaluates the relevant nondetermi.nistic temporal re-lations in multimedia data.Additionally,an interval-based nondeterministie model based ona complete temporal operator set is proposed,providing high-level abstractions and a highdegree of expressiveness for interactive multimedia systems. 展开更多
关键词 multimedia systems SYNCHRONIZATION TEMPORAL modelS TEMPORAL RELATIONS Information REPRESENTATION
在线阅读 下载PDF
Decomposition of Graphs Representing the Contents of Multimedia Data
19
作者 Hochin Teruhisa 《通讯和计算机(中英文版)》 2010年第4期43-49,共7页
关键词 多媒体内容 分解图 数据模型 多媒体数据 递归调用 火焰传播 实例 递归图
在线阅读 下载PDF
上一页 1 2 40 下一页 到第
使用帮助 返回顶部