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Search Results: 1 - 10 of 59027 matches for " Linfeng Yang "
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Surfactant Adsorbed at the Oil-Water Interface and Its Elimination  [PDF]
Linfeng Yang, Leonidas Perez Estrada
Journal of Geoscience and Environment Protection (GEP) , 2015, DOI: 10.4236/gep.2015.32007

Surfactants are widely used in the petroleum industry as one kind of Enhanced Oil Recovery methods (EOR). The oil sands mines in Northern Alberta are the largest one in the world. Due to using sodium hydroxide in bitumen extraction process, there are a lot of surfactant molecules in the tailing water. The surfactants from oil sands industry have brought a potential threat to the environment and human health. Depending on the performance of surfactant at the interface, this work focuses on removing these harmful surfactants from the tailing water and not bringing other possible hazardous substances. Moreover, a mathematical model is built to calculate the removal efficiency of the surfactant. The time required for removing the surfactant is determined experimentally. In conclusion, most of surfactant molecules are adsorbed at the oil/water interface. The fraction of the surfactant staying at the oil/water interface is high. Most of the surfactants in tailing water can be eliminated. The time of surfactant migration can be used for setting up the update time of the oil film in the automatic instrument, which can be designed in the future.

An Energy-aware Hierarchical Architecture Design Scheme  [PDF]
Linfeng YUAN, Yang XU, Xu DU, Wenqing CHENG
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2008, DOI: 10.4236/ijcns.2008.11009
Abstract: Compared with the flat architecture in the design of sensor networks, the hierarchical architecture gains much attractive for the reason of scalability, management and energy efficiency. In order to distribute the energy evenly, nodes act the cluster head in some orders. The existing approaches don’t pay a critical attention to the overhead during the role rotations. And the duration of a round is a priori, which is very application-specific. An energy-aware hierarchical architecture design scheme is put forward in this paper, namely, Adaptive Minimum Rotational Cost (AMRC) cluster formation scheme. The decision of beginning a new round is made adaptively by the cluster head itself. It combines the dynamic and static advantages in the clustering architecture. The simulation results demonstrate AMRC outperforms some other clustering protocols in many aspects.
A QoS-Based Topology Control Algorithm for Underwater Wireless Sensor Networks
Linfeng Liu
International Journal of Distributed Sensor Networks , 2010, DOI: 10.1155/2010/642053
Abstract: The topology control techniques of underwater wireless sensor networks and terrestrial wireless sensor networks are significantly different because of the particularity of underwater environments and acoustic communication. In this paper, an underwater wireless sensor network model was constructed, and six universal topology control objectives were concluded. The QoS topology control problem was mapped into an ordinal potential game model, and a distributed strategy adjustment algorithm for nodes was designed accordingly. The strategy vector resulting from the algorithm converges to the Nash equilibrium; minor complexity and preferable approximate ratios can be represented by the algorithm as well. The performance of the algorithm was analyzed through simulation experiments which indicate a well-constructed topology. Every objective was upgraded when model parameters were set suitable. 1. Introduction Recently, there has been growing interest in the application of sensor networks in underwater environments to enable and enhance applications such as ocean resource exploration, pollution monitoring, and tactical surveillance [1–3]. Before the emergence of wireless sensor networks (WSNs) [4], the perception and collection of underwater data are generally accomplished through wired networks which are very costly. Underwater wireless sensor networks (UWSNs) [5–7] are the enabling technology for these underwater applications. UWSNs consist of sensors that perform collaborative monitoring tasks over a three-dimensional volume. Acoustic communications [8, 9] are the typical physical layer technology in underwater networks. There are three types of nodes in UWSNs: bottom nodes, anchored nodes, and surface sinks. The given phenomenon is observed by interconnected bottom and anchored nodes in charge of relaying data to surface sinks. The architecture of a UWSN is depicted in Figure 1. Figure 1: UWSN architecture. Figure 1 illustrates a three-dimensional UWSN; each bottom or anchored node can monitor and detect environmental events locally, and then transfer these measurements to a surface sink by multihops. Bottom nodes are spread on the seabed. Anchored nodes are equipped with floating buoys that can be inflated by pump. The depth of the anchored node can be regulated by adjusting the length of the wire. QoS is an important issue in WSNs because quality of service has immediate impact on the availability of networks, and topology control is one of the main techniques to improve the quality of WSN service. Due to the specificity and complexity of the water medium,
A Comparative Study of the Metadiscourse Analysis in EFL Textbooks in Japan and China
Linfeng Wang
Journal of Textbook Research , 2012,
Abstract: The purpose of this study is to examine the use of metadiscourse in sev-enth-grade English textbooks in Japan and China in the context of calls for more learner-friendly textbooks. Four textbooks were selected for metadiscourse analysis to determine what kinds of metadiscourse are used to facilitate or affect learner understanding of propositional content. Focusing on metadiscourse’s pedagogical function, Crismore’s (1983) metadiscourse typology for textbooks and other relevant elements were taken into account. The findings imply that although both Japan and China are categorized as EFL countries, their English textbooks display different characteristics in terms of metadiscourse usage, reflecting the different ways in which learning materials are designed and developed. In order to interpret these findings, the impacts of national curricula are discussed.
A Wireless Sensor Network Architecture for Diversiform Deployment Environments
Linfeng Liu
Journal of Networks , 2011, DOI: 10.4304/jnw.6.3.482-489
Abstract: Network architecture is the foundation of network system. Wireless sensor networks (WSN) are always concentrated some key technologies under specific applications, and some prototype systems are developed according to specific applications of environments, but the research on WSN architecture is relatively weak currently. WSN is a highly complex distributed system, the defects in traditional WSN architectures are firstly studied, then the typical requirement objectives of WSN are acquired by analysis, and a set of design principles for WSN model is concluded. Because the WSN is mostly intended for variable and inhospitable environments, where persistent and continuous energy supply is lacking, the environment adaptive and energy efficient capabilities are integrant for WSN architecture. According with other objectives scalability and service-customized, an environment adaptive, energy efficient, hierarchical structure and sub-facets functions architecture model of WSN (EAWNA) is proposed. Furthermore, the design methods, general characteristics and functions of every lay or every module are described and discussed. At last, from the abstract levels of component
Projective spherically symmetric Finsler metrics with constant flag curvature in R^n
Linfeng Zhou
Mathematics , 2010,
Abstract: We investigate projective spherically symmetric Finsler metrics with constant flag curvature in $R^n$ and give the complete classification theorems. Furthermore, a new class of Finsler metrics with two parameters on n-dimensional disk are found to have constant negative flag curvature.
Spherically symmetric Finsler metrics in R^n
Linfeng Zhou
Mathematics , 2010,
Abstract: In this paper, we give the general form of spherically symmetric Finsler metrics in $R^n$ and surprisedly find that many well-known Finsler metrics belong to this class. Then we explicitly express projective metrics of this type. The necessary and sufficient conditions that projective Finsler metrics with spherical symmetry have constant flag curvature are also obtained.
Two dimensional disjoint minimal graphs
Linfeng Zhou
Mathematics , 2011,
Abstract: In this paper, under the assumption of Gauss curvature vanishing at infinity, we will prove Meeks' conjecture: the number of disjointly supported minimal graphs in $\mathbb{R}^3$ is at most two.
The Finsler surface with K=0 and J=0
Linfeng Zhou
Mathematics , 2012,
Abstract: In this short note, we verify R. Bryant's claim: there does exist the singular Landsberg Finsler surface with a vanishing flag curvature which is not Berwaldian.
The spherically symmetric Finsler metrics with isotropic S-curvature
Linfeng Zhou
Mathematics , 2014,
Abstract: In this paper, we investigate the spherically symmetric Finsler metrics with isotropic S-curvature and obtain a characterized equation. As an application, we prove that these metrics with Douglas type must be Randers metrics or Berwald metrics. This result leads to two classification theorems.
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