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基于服务器推送技术和XMPP的WebIM系统实现 被引量:26
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作者 陈航 赵方 《计算机工程与设计》 CSCD 北大核心 2010年第5期925-928,994,共5页
为解决现有WebIM系统中大量用到AJAX周期请求而产生的系统消息延迟,以及客户端和服务器端通信量大的问题,提出了以服务器推送技术作为基础的WebIM系统,并选择XMPP作为服务器和客户端的通信协议。在比较AJAX和Comet技术原理的基础上,给出... 为解决现有WebIM系统中大量用到AJAX周期请求而产生的系统消息延迟,以及客户端和服务器端通信量大的问题,提出了以服务器推送技术作为基础的WebIM系统,并选择XMPP作为服务器和客户端的通信协议。在比较AJAX和Comet技术原理的基础上,给出了Comet技术实现HTTP长连接的策略。通过一个原型WebIM系统,验证了Comet技术在WebIM系统中使用的确可以有效地解决大量AJAX周期请求的问题。 展开更多
关键词 Web即时通讯 Comet技术 可扩展消息处理在线协议 Jetty服务器 服务器推送
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基于Red5的流媒体实时视频系统的设计与实现 被引量:9
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作者 石刚 李子平 徐志立 《仪表技术》 2010年第6期13-15,20,共4页
随着互联网的快速发展,流媒体被广泛地应用于商务和政务领域中,在流媒体的应用中最重要的是流媒体服务器问题。由于现有商业流媒体服务器的完全封闭性和昂贵的价格使得企业很难开发出符合自己需求的流媒体视频系统。文章通过研究与分析... 随着互联网的快速发展,流媒体被广泛地应用于商务和政务领域中,在流媒体的应用中最重要的是流媒体服务器问题。由于现有商业流媒体服务器的完全封闭性和昂贵的价格使得企业很难开发出符合自己需求的流媒体视频系统。文章通过研究与分析开源的流媒体服务器Red5,并建立了基于Red5的流媒体实时视频系统,实现了视频、声音和文字的实时在线。 展开更多
关键词 RED5 RTMP Mina Jetty 流媒体
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基于Servlet3.0的Web异步处理的研究
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作者 李林 周晓慧 《科技风》 2011年第20期19-20,22,共3页
随着互联网应用不断发展,用户体验的不断提升要求能够在很多场景尽量减少交互延时,传统Web请求同步模式不能满足高并发需求,异步模式提出。本文通过分析Web请求同步模式和异步模式的工作原理,归纳了Web异步请求的两种处理场景,对比Tomca... 随着互联网应用不断发展,用户体验的不断提升要求能够在很多场景尽量减少交互延时,传统Web请求同步模式不能满足高并发需求,异步模式提出。本文通过分析Web请求同步模式和异步模式的工作原理,归纳了Web异步请求的两种处理场景,对比Tomcat、Jet-ty、Servlet3提供的异步处理实现,分析了Servlet3异步模式的优势,设计了基于Servlet3的web异步请求模型,为互联网B/S实时应用开发者提供了参考。 展开更多
关键词 Servlet3 异步处理 TOMCAT Jetty COMET
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基于无线传感器网络的智能家居监控平台设计 被引量:5
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作者 龚婉婉 刘士兴 冯婷婷 《信息网络安全》 2015年第3期79-83,共5页
随着社会经济水平的发展,人们的生活开始追求个性化、自动化,对家居环境的档次的需求也越来越高,追求居住环境的智能化、安全化。当今社会,以嵌入式系统和网络技术为基础,用户体验为核心导向的智能家居技术正在蓬勃发展,具有广阔的应用... 随着社会经济水平的发展,人们的生活开始追求个性化、自动化,对家居环境的档次的需求也越来越高,追求居住环境的智能化、安全化。当今社会,以嵌入式系统和网络技术为基础,用户体验为核心导向的智能家居技术正在蓬勃发展,具有广阔的应用前景。文章设计了一种基于无线传感器网络的智能家居监控平台,将温度、烟雾、一氧化碳传感器与CC2530芯片搭配,负责采集环境的温度值、烟雾浓度值、一氧化碳浓度值,并且通过Zigbee无线传输网络将采集到的数据传输到嵌入式控制器中,搭配视频监控模块,进行图像信息的采集以及实时传递。系统主控制器的设计采用嵌入式ARM11芯片,通过移植主流的操作系统——Android系统,引入嵌入式服务器i-Jetty,建立了Android Web服务器,并且结合SQLite数据库技术,对系统数据进行存储和管理。用户可以通过手机或PC端的Web浏览器访问服务器,对家居系统环境实时监控。 展开更多
关键词 无线传感器网络 智能家居 ANDROID Jetty 嵌入式服务器
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Wave Forces on Submerged Semi-Circular Breakwater and Similar Structures 被引量:15
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作者 XIE Shileng Prof. Senior Engineer, The First Design Institute of Navigation Engineering, Ministry of Communications of China, Tianjin 300222, P. R. China. 《China Ocean Engineering》 SCIE EI 1999年第1期63-72,共10页
The results of design and experiment of a submerged semi-circular breakwater at the Yangtze estuary show that the submerged structure will be unsafe when the general empirical wave force formula for semi-circular brea... The results of design and experiment of a submerged semi-circular breakwater at the Yangtze estuary show that the submerged structure will be unsafe when the general empirical wave force formula for semi-circular breakwater is used in design. Therefore, a new calculation method for the wave forces acting on a submerged semi-circular structure is given in this paper, in which the wave force acting on the inside circumference of semi-circular arch is included, and the phase modification coefficient in the general empirical formula is adjusted as well. The new wave force calculation method has been Verified by the results of seven related physical model tests and adopted in the design of the south esturary jetty of the first stage project of Deep Channel Improvement Project of the Yangtze River Estuary, the total jetty length being 17.5 km. 展开更多
关键词 semi-circular breakwater submerged structure estuary jetty wave force
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Experimental Investigation of Irregular Wave Uplift Force on Deck of Exposed High-Pile Jetties 被引量:3
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作者 陈国平 孟艳秋 严士常 《China Ocean Engineering》 SCIE EI 2010年第1期67-78,共12页
A laboratory setup was developed to investigate irregular wave uplift loads on exposed high-pile jetties. It is shown that the dimensionless uplift load increases to the maximum with an increasing relative clearance a... A laboratory setup was developed to investigate irregular wave uplift loads on exposed high-pile jetties. It is shown that the dimensionless uplift load increases to the maximum with an increasing relative clearance and then decreases. The relative clearance corresponding to the peak force is linked to a range from 0.4 to 0.8. When the relative clearance exceeds a certain value, the wave can not reach the underside of the deck and the force becomes zero. Distinct trends of dimensionless force with a relative width of deck show that the force tends to decrease as the relative deck width increases, and then the decrease slows down after the relative deck width increases or decreases to a certain value. The pressure distribution length associated with the maximum uplift force is equivalent to the wave contact width x. When x is larger than the width of deck B, it is taken as B. The statistical distribution of loads obeys the Weibull distribution. The results from the analyses of the real data suggest a new dimensionless prediction model on wave-in-deck uplift loads and the conversion ratio between wave loads at different exceedance probabilities. A comparison is made between the new prediction model and the existing widely used three prediction models. These results are used as useful references for structural design of the jetty. 展开更多
关键词 irregular wave uplift force high-pile jetty
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Hydrodynamic Coefficients and Wave Excitation Forces for A Ship near A Quay 被引量:1
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作者 M. Hasan Adil 段文洋 《海洋工程:英文版》 SCIE EI 2004年第1期119-128,共10页
In this paper, the effects of a quay or a solid jetty on hydrodynamic coefficients and vertical wave excitation forces on a ship with or without forward speed are discussed. A modified simple Green function technique ... In this paper, the effects of a quay or a solid jetty on hydrodynamic coefficients and vertical wave excitation forces on a ship with or without forward speed are discussed. A modified simple Green function technique is used to calculate the 2D coefficients while the strip theory is used to calculate the 3D coefficients. Wave excitation forces are also calculated with the strip theory. Numerical results are provided for hydrodynamic coefficients and vertical wave excitation forces on a 200 000 DWT tanker ship. It is found that the quay has a considerable effect on the hydrodynamic coefficients and wave excitation forces for a ship. 展开更多
关键词 hydrodynamic coefficients Green function technique strip theory quay jetty
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Computation of Diffraction of Irregular Waves Behind Double Jetty 被引量:1
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作者 Yao Guoquan , Ma Zhixiong and Ding Bingchan Senior Engineer, River and Harbour Department, Nanjing Hydraulic Research Institute, Nanjing Assistant Engineer, River and Harbour Department, Nanjing Hydraulic Research Institute, Nanjing 《China Ocean Engineering》 SCIE EI 1991年第4期429-440,共12页
The coefficient of deffraction of regular waves behind the double jetty has been computed in this paper at first by using the singularity distribution method. The model tests conducted for diffraction of irregular wav... The coefficient of deffraction of regular waves behind the double jetty has been computed in this paper at first by using the singularity distribution method. The model tests conducted for diffraction of irregular waves with a unidirectional frequency spectrum have confirmed good agreement between the data measured in experiments and the results computed by the singularity distribution method plus the linear superposition method for the energy of component waves in the directional frequency spectra. Therefore, this technique for component waves in the directional spectra has been further used to compute diffraction of irregular waves of multidirection, including the employment of a directional distribution function of the cos2 type, as well as the Bretschneider-Misuyann frequency spectrum. 展开更多
关键词 DIFFRACTION irregular waves double jetty ocean engineering
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Effect of the Twin Jetties as A Regulating Structure at the Tao-er Estuary 被引量:1
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作者 陆培东 徐敏 +1 位作者 张金善 雷智益 《China Ocean Engineering》 SCIE EI 2002年第2期219-226,共8页
The phase one project of the twin jetties at the Tao-er Estuary yields no effect on the flow, and there is a large area of deposition. A numerical model is employed to simulate the flow field, and the scouring and sil... The phase one project of the twin jetties at the Tao-er Estuary yields no effect on the flow, and there is a large area of deposition. A numerical model is employed to simulate the flow field, and the scouring and silting in the channel between the two jetties are analyzed. The results show that the effective tidal flux between the two jetties is reduced due to the notch located at the heel of the east jetty, and the effect of contraction-flush is not obvious. As for the regulation of this kind of estuary under the tide action, the capability of tidal flux should be fully used. 展开更多
关键词 twin jetties numerical model regulation works Tao-er Estuary
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一种基于Terracotta的透明分布式CometD引擎实现
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作者 任志平 《计算机应用与软件》 CSCD 2011年第12期11-13,18,共4页
CometD引擎采用了在服务器间进行消息广播的方式来实现对分布式的支持,它需要服务器集群节点之间使用HTTP协议进行通信,这种分布式的解决方案首先需要大量的编程工作,另外广播方式影响服务器的可扩展性。引入Terracotta技术来改进Comet... CometD引擎采用了在服务器间进行消息广播的方式来实现对分布式的支持,它需要服务器集群节点之间使用HTTP协议进行通信,这种分布式的解决方案首先需要大量的编程工作,另外广播方式影响服务器的可扩展性。引入Terracotta技术来改进Comet的现有分布式解决方案,该方案的优点是透明地实现CometD引擎的分布式,大大减少了开发者的工作量。 展开更多
关键词 COMET 分布式 Jetty Terracotta
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Computation of Diffraction of Irregular Waves Behind Single Jetty 被引量:1
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作者 Yao, Guoquan Ma, Zhixiong Ding, Bingeau 《China Ocean Engineering》 SCIE EI 1991年第3期321-334,共14页
This paper presents a calculation method for the diffraction of both regular waves and irregular waves of the single directional frequency spectrum behind a single jetty with a theoretical analysis, which has been con... This paper presents a calculation method for the diffraction of both regular waves and irregular waves of the single directional frequency spectrum behind a single jetty with a theoretical analysis, which has been confirmed through the model experiments, derives a method of computing the diffracted irregular waves behind the single jetty with the theoretical analysis on the basis of computation of the field data and gives the formulas and the figures of the computation of wave diffractions behind the vertical wall or mound single jetties. 展开更多
关键词 Jetties Mathematical Models
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Servlet Container的分析与设计
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作者 王概凯 曹晓东 《电脑开发与应用》 2004年第5期39-41,共3页
针对一个开源的 Servlet Container Jetty的源码进行分析 ,讨论设计了一个 Servlet
关键词 SERVLET Container Web服务器 JAVA技术 SERVLET Specification Jetty org.mortbay.http包 Class LOADER 分析 设计
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Quality Assessment of Concrete Blocks Exposed in Nature for Eighty Years
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作者 Hu Yuchu , Wu Shaozhang Lu Liyun Senior Engineer, Nanjing Hydraulic Research Institute, 210029 Nanjing Professor and Senior Engineer, Nanjing Hydraulic Research Institute, 210029 Nanjing Assistant Engineer, Nanjing Hydraulic Research Institute, 210029 Nanjing 《China Ocean Engineering》 SCIE EI 1992年第4期455-470,共16页
The concrete blocks used on a jetty in Shanghai were made in 1909 and 1910. Having been exposed in nature for 80 years, now there are 4600 pieces of blocks left on the jetty. Comprehensive inspections, such as externa... The concrete blocks used on a jetty in Shanghai were made in 1909 and 1910. Having been exposed in nature for 80 years, now there are 4600 pieces of blocks left on the jetty. Comprehensive inspections, such as external appearance examination, core-drilling of concrete blocks, ultrasonic detection, nuclear densimeter inspection and in-door and out-door chemical analysis, show that 75% of the blocks are of the rebound number of 21 - 23, and the saturated limit compressive strength and dry limit compressive strength of 10MPa; the carbonized depth of concrete is 1 - 2 mm. Compared with the state of the jetty in 1968, already used for 60 years then, the jetty is expected to serve another 40 years or more after being repaired. 展开更多
关键词 jetty concrete block damage inspection DURABILITY
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The Behaviour of LNG Carrier Moored to a Jetty Exposed to Waves,Swell,Unsteady Wind and Current
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作者 J. E. W. WICHERS 《China Ocean Engineering》 SCIE EI 1999年第1期81-92,共12页
Most terminals for tankers are piers and sea islands, while other types include single point moorings and multiple-buoy moorings. The LNG and LPG carrier moored to the jetty is a very common terminal for transfer of g... Most terminals for tankers are piers and sea islands, while other types include single point moorings and multiple-buoy moorings. The LNG and LPG carrier moored to the jetty is a very common terminal for transfer of gas in open seas. It is important to estimate the motions and line tensions of the LNG carrier when it moors to a jetty in metocean environment. Normally, the motions of the LNG carrier would be restricted by the loading arm, which is connected to LNG carrier's manifold. An example of 125,000 m(3) LNG carrier moored to a jetty exposed to a set of environment conditions is given. A mathematical model which is based on the equations of motion in the time domain is used to the analysis of LNG moored to an offshore jetty exposed to waves, swell, wind and current. By means of a time domain computer program TERMSIM computations are carried out to determine and optimize the lay-out and / or orientation of the jetty and mooring gear in terms of forces in mooring lines and fenders and the envelope of motions of the loading arms. The purpose of this study is to determine the sensitivity of the mooring system and carrier motions to the combinations of wind waves with and without swell, steady wind and wind spectra. The results can be consulted by the designer in the design of jetties. 展开更多
关键词 mooring system dynamic response time domain analysis jetty
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Genesis and Distribution of Ultra-alkaline Magmatism within the East Antarctic Associated with the Kerguelen Plume Activity
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作者 Nadezhda M.Sushchevskaya Boris V.Belyatsky Robert Sh.Krymsky 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2016年第S1期198-199,共2页
Alkaline magmatism is often associated with the initial or final stages of huge plume activity.The alkaline bodies are most often found within the boundary area of plume impact upon the continents.The initial stages o... Alkaline magmatism is often associated with the initial or final stages of huge plume activity.The alkaline bodies are most often found within the boundary area of plume impact upon the continents.The initial stages of the 展开更多
关键词 Genesis and Distribution of Ultra-alkaline Magmatism within the East Antarctic Associated with the Kerguelen Plume Activity Jetty
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Coastal Erosion in Yasawa Islands,Fiji
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作者 Nils-Axel Morner Pamela Matlack Klein 《Natural Science》 2017年第5期136-142,共7页
Coastal erosion may have many different causes. Wherever we came across erosion problems on the Yasawa Islands in Fiji, they had causes other than sea level rise. We present two case studies. At one site, the beach er... Coastal erosion may have many different causes. Wherever we came across erosion problems on the Yasawa Islands in Fiji, they had causes other than sea level rise. We present two case studies. At one site, the beach erosion was caused by the construction of a stonewall diverting the currents in a gyre that hit the shore causing local beach erosion. At another site, extensive erosion caused removal and lateral re-deposition of huge quantities of sand. From the Google Earth images we can infer a date between 2005 and 2009 for this change in shore conditions. We suggest that the shallow-water sand was destabilized by the commercial harvesting of thousands of sea cucumbers (Holothuria scabra). These animals, by their sheer numbers and ecological behavior, were exerting a stabilizing influence on the shallow-water sandy deposits off the beach at Yageta Village. In both cases, the erosion was caused by human action. The coasts all along the Yasawa Islands are characterized by coastal stability. The presence of extensive rock-cut platforms and notches, as well as the occurrence of corals grown into “mini-atolls” are indicative of a stable sea level throughout the islands. 展开更多
关键词 Coastal Erosion CURRENTS Jetties Sea Cucumbers Stable Sea Level Fiji
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JETTIS织机绳状绞边装置及其问题分析
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作者 张俊康 《陕西纺织》 1994年第3期74-76,共3页
关键词 喷气织机 JETTIS型 绳状绞边装置
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基于Jetty的网页防篡改技术的设计和实现 被引量:1
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作者 罗红飞 孟庆生 徐中干 《网络安全技术与应用》 2010年第5期4-6,共3页
本文提出并实现了架设在符合J2EE标准的Web服务器上的网页防篡改系统,该系统主要采用Java语言开发和实现,能够对目前各种主流操作系统平台上的网页内容进行实时监控,发现网页被篡改时能及时恢复并报警,有效的保护目标网站的安全。
关键词 核心内嵌 散列函数 篡改 网页保护 jetty解析
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An experimental study of impact loading on deck of shore-connecting jetties exposed to oblique waves and current 被引量:3
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作者 孟艳秋 陈国平 +1 位作者 严士常 童朝锋 《Journal of Hydrodynamics》 SCIE EI CSCD 2014年第2期216-225,共10页
The impact pressure from waves is an important issue to be considered in the design of coastal structures. In this paper, the waves acting on the deck of a shore-connecting jetty on a slope exposed to oblique waves an... The impact pressure from waves is an important issue to be considered in the design of coastal structures. In this paper, the waves acting on the deck of a shore-connecting jetty on a slope exposed to oblique waves and in the presence of current are examined based on laboratory experiments. The impact pressures are measured on a 1:50 scale model of a jetty head with down-standing beams and berthing members. The relations of the impact pressure with the incident wave angle and the current velocity are examined. It is shown that the impact pressure is sensitive to the wave angle and the current velocity. A computational model for the impact load on the deck of shore-connecting jetties exposed to oblique waves and current is developed. 展开更多
关键词 WAVE CURRENT impact pressure shore-connecting jetty on a slope
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