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711.
During recently years, several OpenFlow-enabled testbeds have been deployed in world-wide research community. Typically, these OpenFlow-enabled testbeds need to stitch to other testbeds to link to virtual servers and immit experimentation traffic. From the view point of researchers, these OpenFlow-enabled testbeds only provide OpenFlow networking resource, and they have to resort to other experiment infrastructure to provide computing and storage resource. Due to the OpenFlow networking and other resource belongs to different infrastructure provider and is managed by their own control software, it is difficult to coordinate these partners to provide a full programmable experiment environment. Meanwhile, the control software of these testbeds are tight coupling with their substrate resources, which means that these substrate resources, together with virtualization technologies, are permanently dedicated to the control software and difficult to be used by other services. In this paper, a new future Internet testbed architecture based on the open Infrastructure-as-a-service cloud and software defined network (SDN) paradigm is proposed. It extends the current virtual network service by adding programmable virtual switch and controller resources that can be controlled by the researcher. Its loose coupling model allows the testbed operator decouple the experiment service from the infrastructure provider, which is a more flexible way to build the testbed. The initial prototype implementation in this paper shows that this new testbed architecture built on IaaS cloud and SDN is feasible and flexible to provide programmable virtual network service. 相似文献
712.
Shikuan Yang Michael Ian Lapsley Bingqiang Cao Chenglong Zhao Yanhui Zhao Qingzhen Hao Brian Kiraly Jason Scott Weizhou Li Lin Wang Yong Lei Tony Jun Huang 《Advanced functional materials》2013,23(6):720-730
A new strategy to achieve large‐scale, three‐dimensional (3D) micro‐ and nanostructured surface patterns through selective electrochemical growth on monolayer colloidal crystal (MCC) templates is reported. This method can effectively create large‐area (>1 cm2), 3D surface patterns with well‐defined structures in a cost‐effective and time‐saving manner (<30 min). A variety of 3D surface patterns, including semishells, Janus particles, microcups, and mushroom‐like clusters, is generated. Most importantly, our method can be used to prepare surface patterns with prescribed compositions, such as metals, metal oxides, organic materials, or composites (e.g., metal/metal oxide, metal/polymer). The 3D surface patterns produced by our method can be valuable in a wide range of applications, such as biosensing, data storage, and plasmonics. In a proof‐of‐concept study, we investigated, both experimentally and theoretically, the surface‐enhanced Raman scattering (SERS) performance of the fabricated silver 3D semishell arrays. 相似文献
713.
The nutritional requirements of Aeropyrum pernix were studied to investigate the growth of a hyperthermophilic marine archaeon in a defined medium. Various nutrients including sugars, amino acids, and nucleoside bases were tested to determine their effects on cell growth. It was found that adenine and six amino acids (Arg, Ile, Len, Lys, Met, Val) are essential for the growth of A. pernix. An artificial seawater-based medium, containing 11 amino acids, adenine, vitamins, KH2PO4, Na2S2O3 and trace minerals, enabled the growth of A. pernix at a cell density and specific growth rate similar to those obtained with complex media. 相似文献
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715.
Ekram Hossain Dusit Niyato Dong In Kim 《Wireless Communications and Mobile Computing》2015,15(11):1530-1564
The cognitive radio (CR) paradigm for designing next‐generation wireless communications systems is becoming increasingly popular, and different aspects of it are being implemented in currently available wireless systems. In the last decade, a significant amount of research efforts has been made to solve CR challenges, and several standards related to CR and dynamic spectrum access have been developed. Also, there have been advances in software‐defined radio platforms to implement the CR systems. In this article, we provide a comprehensive survey on the evolution of CR research covering aspects such as spectrum sensing, measurements and statistical modeling of spectrum usage, physical layer aspects such as waveform and modulation design, multiple access, resource allocation and power control, cognitive learning, adaptation and self‐configuration, multihop transmission and routing, and robustness and security in CR networks. Also, state‐of‐the‐art research on the economics of CR networks, CR simulation tools, testbeds and hardware prototypes, CR applications, and CR standardization efforts is summarized. Emerging trends on CR research and open research challenges related to the cost‐effective and large‐scale deployment of CR systems are outlined. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
716.
Takao Tsukutani Masami Higashimura Yasuaki Sumi Yutaka Fukui 《International Journal of Electronics》2013,100(3):307-314
This paper presents a realization of current-mode active-only filter. The proposed filter is constructed employing operational amplifiers and operational transconductance amplifiers (OTAs). The circuit can realize biquadratic transfer function, and the circuit characteristics can be electronically tuned through adjusting the transconductance gains of the OTAs. An example is given together with simulated result by PSPICE. The circuit configuration is very suitable for implementation in both bipolar or CMOS technologies. 相似文献
717.
随着智能电网和能源互联网的不断深入发展和推进,云计算、数据仓库、数据挖掘以及虚拟化等技术在电力行业的成熟应用,现有电网已无法满足业务的需求。软件定义网络(software defined network,SDN)作为新兴网络架构实现了控制功能和数据转发功能的解耦,是未来电力通信网络架构的选择之一。文中通过对SDN网络原理的论述,详细讨论了基于SDN的电力通信网络需要解决的关键技术,主要包括网架性能、安全性、时延、可扩展性、链路可靠性、容错性和兼容性,最后展望了软件定义网络相关技术在电力系统中的应用领域。 相似文献
718.
The network testbed based on software defined networking (referred as SDN testbed) has attracted extensive attention in the academic and industrial circles in recent years,and there have been many valuable cases of system/platform construction.Therefore,an overview of the SDN testbed was intended to conduct in the global scope.Firstly,the advantages of the SDN testbed and the basic design principles of the large-scale SDN testbed was explored comparing with the traditional network testbed.Secondly,in-depth analysis of existing SDN testbed projects was provided from the aspects of the project objectives and progress,the key technologies,network deployment,and featured applications.Finally,the challenges faced in this field were described in terms of network slicing,light and wireless convergence,security,and reliability.Future research directions are also suggested. 相似文献
719.
720.