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1.
为了解决在带宽不足时,蓝牙数据传输速率不高的现象。提出了一种基于蓝牙的复合通信协议。该协议作用在同时拥有蓝牙和其它多种通信方式的设备上,以蓝牙作为基本通信通道,可以根据传输的需要即时的选择其它通信通道作为辅助数据传输通道进行高传输率的数据传输。实现了以蓝牙为桥梁选择性的建立其它通信通道进行数据传输的功能。相比传统的蓝牙传输方式,该协议能够将设备上原本孤立的蓝牙和其它通信资源有机的整合在一起协同完成数据传输任务,提高了设备阃的数据传输效率,在音视频传输业务方面有着较好的应用价值。  相似文献   

2.
由于节点配备的能量有限,采用分簇技术可以极大地降低节点与Sink节点通信的能耗,簇群的拓扑结构决定整个簇群的能量消耗速度。基于传感器节点的数据传输能量模型,研究了单跳和多跳两种簇群拓扑结构的能量消耗的理论模型及能量消耗公式,并分析不同网络拓扑结构对网络能耗的影响。  相似文献   

3.
为了解决在带宽不足时,蓝牙数据传输速率不高的现象。提出了一种基于蓝牙的复合通信协议。该协议作用在同时拥有蓝牙和其它多种通信方式的设备上,以蓝牙作为基本通信通道,可以根据传输的需要即时的选择其它通信通道作为辅助数据传输通道进行高传输率的数据传输。实现了以蓝牙为桥梁选择性的建立其它通信通道进行数据传输的功能。相比传统的蓝牙传输方式,该协议能够将设备上原本孤立的蓝牙和其它通信资源有机的整合在一起协同完成数据传输任务,提高了设备间的数据传输效率.在音视频传输业务方面有着较好的应用价值。  相似文献   

4.
为了解决在带宽不足时,蓝牙数据传输速率不高的现象。提出了一种基于蓝牙的复合通信协议。该协议作用在同时拥有蓝牙和其它多种通信方式的设备上,以蓝牙作为基本通信通道,可以根据传输的需要即时的选择其它通信通道作为辅助数据传输通道进行高传输率的数据传输。实现了以蓝牙为桥梁选择性的建立其它通信通道进行数据传输的功能。相比传统的蓝牙传输方式,该协议能够将设备上原本孤立的蓝牙和其它通信资源有机的整合在一起协同完成数据传输任务,提高了设备间的数据传输效率.在音视频传输业务方面有着较好的应用价值。  相似文献   

5.
延迟容忍网络是一种通过节点机会通信的网络类型.由于该网络中节点不易预测的移动性模式和容易中断的连接,路由算法一直是DTNs中研究的重点.但是目前从节省能量消耗角度提出的路由算法较少.文章提出一种基于节点有效交互度和效用的节能路由策略.首先,从节点有效交互度出发来进行转发传输速率控制,在节能与转发成功率之间自适应调整.其次,从节点效用出发设置消息携带者转发概率,选择合适的节点进行消息转发,避免网络产生过多消息副本.再次,仿真实验结果显示,与其他路由算法相比,该文提出的算法在保障网络消息传递率的基础上可以降低约6%~15%节点能量消耗.  相似文献   

6.
为了解决在带宽不足时,蓝牙数据传输速率不高的现象.提出了一种基于蓝牙的复合通信协议.该协议作用在同时拥有蓝牙和其它多种通信方式的设备上,以蓝牙作为基本通信通道,可以根据传输的需要即时的选择其它通信通道作为辅助数据传输通道进行高传输率的数据传输.实现了以蓝牙为桥梁选择性的建立其它通信通道进行数据传输的功能.相比传统的蓝牙传输方式,该协议能够将设备上原本孤立的篮牙和其它通信资源有机的整合在一起协同完成数据传输任务,提高了设备间的数据传输效率,在音视频传输业务方面有着较好的应用价值.  相似文献   

7.
针对节点数目较少且节点相对移动性较小的应用场景,给出了一种基于蓝牙的Ad hoc实现方案,包含组网路由设计与上层应用框架设计,提出了一种适于在蓝牙L2CAP层实现的分布式路径发现算法,并构建了实验系统对此方案进行了验证与测试,结合实验系统的测试数据,对蓝牙Ad hoc性能进行了详细的理论推导与比较分析,包含建链耗时分析、带宽与平均时延分析,结果表明,该蓝牙Ad hoc方案适于多跳通信,能很好地承载文本传输、语音通信与视频通信等上层业务.  相似文献   

8.
为了能有效地利用节点能量的异构性,降低网络能耗、延长网络稳定周期,提出了一种同时考虑节点剩余能量和节点至基站距离的多级能量异构无线传感器网络的分簇路由算法.在节点簇间综合考虑簇头剩余能量及其与基站的通信能耗,以选择合适的下一跳路由节点.仿真结果表明,该算法可以有效地均衡网络能量消耗,延长网络稳定周期.该路由算法在维持节点存活个数、降低网络能量消耗及增加网络数据传输吞吐量等指标方面优于几种常见传感器网络路由算法,表明在综合考虑能量和距离等因素后能够获得比单一考虑能量或者距离的算法更优的运行结果.  相似文献   

9.
针对无线传感反应网络低功耗路由设计需求,提出了一种基于最大共享路径的无线传感反应网络路由协议设计方案,通过在无线传感反应传感网络结构中,选取无线传感节点以及反应节点,构建一个从事件源到其他反应节点的具备最大共享路径的传播策略.以此在确保无线传感反应网络数据传输的可靠性的前提下,尽可能的降低整个无线传感网络中的能量消耗,仿真测试表明,本文设计的无线传感反应网络路由协议,比传统的贪婪算法传输跳级高5.6%.整个传输网络的平均能量消耗,降低约27.3%.  相似文献   

10.
针对无线传感器网络能量多路径路由算法存在的缺陷及其原因,提出一种基于动态优先级的能量多路径路由算法。该路由算法以节点距汇聚节点的路径跳数值替代路径能耗代价确定其优先级,并在数据传输过程中根据节点的能量消耗不断调整优先级,降低了算法的复杂度,避免了周期性路由维护所带来的时间与能量损失。仿真结果表明,该算法能有效降低和平衡各节点的能耗,延长整个网络的生存周期。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

14.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

15.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

16.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

17.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

18.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

19.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

20.
1 Rise of studies on climate change's effects on biodiversity
Until the 1980s, climate change and biodiversity were studied as two independent disciplines for more than a century. In 1992, the Ecological Society of America's annual report named climate change, biodiversity, and the sustainable ecological system as the three major global environmental issues of the twenty-first century [1].  相似文献   

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