1,721,283 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Development of an Integrated Magnetic System Assisted by Electromagnetic Simulation
No full textIn DC/DC converter systems, power electronic circuits are reaching switching efficiencies close to 100 percent nowadays. Thus, most of the energy loss appears inside the passive magnetic circuit of the converter, which at the same time is the component that requires most space in the system. In order to battle this issue, research during the last century has been focused on planarization, hybridization and integration techniques with the goal to achieve higher efficiencies and decrease the profile and volume of the devices. In addition, higher frequencies have been applied to achieve a higher power density of the magnetic systems, but with the negative consequence of stronger parasitic effects such as proximity and skin effects inside the magnetic circuit.
This thesis deals with the development of an integrated magnetic system in a L-C-T (Inductor-Capacitor-Transformer) configuration, with the assistance of Finite Element Method (FEM) computer modeling, which is supportively used to accelerate the development process. Computational simulation method is used to indicate and address the physical issues, which cannot be identified with conventional measurement methods.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)Griffith School of EngineeringScience, Environment, Engineering and TechnologyFull Tex
Efficient Antennas for Wearable Wireless Sensor Nodes
No full textWearable wireless sensors are a part of human life in the future for applications such as healthcare, sports, navigating, security etc. The number of wearable wireless sensors for fitness and healthcare applications will reach 90 million shipments by 2017 base on ABI research report [1]. The IEEE Standard 802.15.6 for local and metropolitan area networks, part 15.6, “Wireless Body Area Networks” was published on February 2012 to specify the short range wireless communication in the vicinity or inside of the human body [2]. This shows the importance of research needed to maximize the quality of wireless communications around the body. The human body is a lossy medium that absorbs the radio frequency (RF) energy and this affects the propagation of electromagnetic waves used in wireless communication. The specific absorption rate (SAR) is defined by the Federal Communications Commission (FCC) to identify criteria for measuring the rate of absorption and amount of interaction between the body and a source of RF energy [3].Thesis (PhD Doctorate)Doctor of Philosophy (PhD)Griffith school of EngineeringScience, Environment, Engineering and TechnologyFull Tex
Wireless Power Transfer For Automated Guided Vehicles (AGV)
No full textAutonomous Guided Vehicles (AGV) are computer controlled electric vehicles and robots that has been programmed to execute precise tasks, such as material handling and transport of goods. To maintain the work productivity, AGV requires fast charging methods while keeping the environment safety and products integrity. Popular charging methods are contact-based and wireless charging. Contact-based systems offers fast and efficient charging solutions, however, due contact friction, the constant maintenance and explosion hazard in dust environments made this solution be replaced with wireless power transfer (WPT) applications. Wireless charging are contactless approaches that assure the safety of living beings and environment security. Besides that, wireless systems are easy to install with low maintenance and long life, becoming a cost benefit solution.
This thesis investigates and develops novel WPT technologies for AGV. Firstly, an analysis of current WPT technologies defines the target AGV application. Small vehicles units are the focus of the wireless model's system due to the possibility of resizing pads designs for larger AGV applications. [...]Thesis (PhD Doctorate)Doctor of PhilosophySchool of Eng & Built EnvGriffith SciencesFull Tex
Modelling and Design of Advanced High Frequency Transformers
No full textCarbon dioxide emission reduction has been a popular topic in recent years because it alleviates the current global warming crisis. Hence, there is an urgent need to adapt current technologies to help reduce carbon dioxide emissions before the global warming situation worsens. Amongst carbon dioxide reduction technologies, Electric Vehicle (EV) and renewable energy technologies are most likely to assist in improving this current status of the environmental issue in coming years. Due to increased interest in energy storage systems, such as EV and renewable energy, there is a pending need to improve the existing DC-DC converters used. The DC-DC converter systems used at present are usually bulky, costly and inefficient due to their low operating frequency. Hence, by increasing the operating frequency of the DC-DC converter, the size of the passive elements can be greatly reduced. Among these passive elements, the transformer occupies the most important role indisputably.
A High Frequency Coaxial Transformer (HFCT), with a range of 1 kW to 20 kW was designed and introduced in this dissertation. The operating frequency was raised to between 100 kHz and 300 kHz in order to achieve high power densities and high performance efficiency. However, the coupling capacitance accompanied by an increased operating frequency (which couples high frequency noise between the primary and secondary windings) can cause serious common mode problems. Hence, the Faraday shield was placed between the windings of introduced transformers. This reduces the coupling capacitance and consequently the electromagnetic interference. The shielding effect analysis has been conducted to verify the HFCT performance with the insertion of the Faraday shield.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)Griffith School of EnvironmentScience, Environment, Engineering and TechnologyFull Tex
Supplemental Material - Prognostic Value of Tumor Size in Colon Cancer—Smaller is Better?
No full textSupplemental Material for Prognostic Value of Tumor Size in Colon Cancer—Smaller is Better? by Yan Meng, Bingyan Wang, Hsinyi Lin, Fei Li, Siyi Lu, Junwei Wang, Hao Wang, Limei Guo, Xin Zhou, and Wei Fu in The American Surgeon</p
Improving Security in WLAN With the Use of Smart Antennas
No full textWireless communication systems are increasingly deployed by family, businesses, government and SOHO users because of the freedom wireless communications afford, simplicity of installation and ease of use. Along with its rapid development, the security problem in wireless communication network has attracted more and more attention. It has been estimated that the IEEE 80.211 standard is susceptible to attacks both on data content and user authentication, such as eavesdropping, spoofing and Denial of Service. These attacks are due to the standard's inherent flaws and space signal sharing caused by the omni-directional antenna it usually uses. In recent years, few studies have been undertaken which examine the use of the smart directional antenna to mitigate the security risks in mobile wireless computing networks. One of the major reasons is the antenna size, as portability is a key requirement. Due to the dielectric-material embedding and FDTD optimal design technology, a smart antenna with controllable directionality can now achieve an overall volume reduction of 80%. This has promise for application in the wireless security realm. This thesis provides a conventional background in wireless computing networks and security theory. In addition, security level definition, program in Matlab™ and corresponding experimental results are provided. To show the effectiveness of improving security in WLAN with the use of a smart directional antenna, this thesis proposes a model for predicting electromagnetic environments using a directional transmission antenna based on the Finite Element method. To validate the numerical results, a new experimental method (using Network Stumbler software) to measure the signal strength in different locations is introduced. Results from experiments using the two methods are consistent. The latter method gives the users the possibility of using a laptop (with an appropriate wireless card, software and roguing around) to detect the real-time signal strength in different locations instead of using expensive measure apparatus. Such an advantage can be valuable for the efficient implementation of indoor wireless networks for security purposes. Finally, it contributes a security solution using DE-ESMB and DE-ESPAR smart antennas in WLAN. Through these simulated and experimental results, one can conclude that the security performance in WLAN can be greatly improved by using smart directional antenna. There are five chapters in this thesis: Chapter 1 introduces the wireless communication network. Information about architecture, topology and popular wireless standards is presented in this chapter. Chapter 2 investigates the security problem in IEEE 802.11 Standards. Recent improvements in security, and their limitations, are also included. This problem is investigated by performing laboratory experiments, including a real attack on 802.11 Standards and packet capture experiments using AiroPeek NX software. Chapter 3 describes the useful parameters of smart directional antennas, and then presents the security level definition in WLAN. Simple software in Matlab™ to determine the security level according to the beamwidth of the adopted antenna is also introduced. Chapter 4 is the important part of this thesis. Simulation results of signal strength in different locations using FEMLAB™ are presented, which are consistent with the follow-up experimental results carried out in a typical office area. This chapter also describes the final security solution using the newly-designed DE-ESMB and DE-ESPAR directional antennas. Chapter 5 is a summary of the thesis. It presents the conclusions and suggests area of future research for improving the security level using smart antennas in WLAN.Thesis (Masters)Master of Philosophy (MPhil)School of EngineeringFull Tex
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