The Experts below are selected from a list of 113139 Experts worldwide ranked by ideXlab platform
Fitzgerald Pio - One of the best experts on this subject based on the ideXlab platform.
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Flight control system design for autonomous UAV carrier landing
School of Engineering, 2004Co-Authors: Fitzgerald PioAbstract:The challenge of integrating the UAV fleet into the carrier landing Operational Structure with respect to navigation and control strategies is addressed. A simulation model was developed which includes an aircraft model, an atmosphere model and an aircraft carrier motion model. The six degree of freedom non-linear aircraft model is based on the aerodynamic characteristics of the Mk 4a Jindivik extended to include rudder, spoiler and thrust vectoring controls, and an undercarriage model. The atmosphere model includes a carrier landing atmospheric disturbance model. The six degree of freedom aircraft carrier motion model is based on the ship motion simulation program SEAWAY. A Navigation System was developed which conforms to current Operational procedures and future military navigation goals. This Navigation System continuously predicts the position in space where touchdown on the carrier deck will take place, based on aircraft position, the relative velocity between the aircraft and carrier, and the motion time history of the carrier. A reference flight path to the predicted touchdown point is continuously defined. The aircraft deviation from this flight path is determined and input to the autoland control system. For the purposes of this study perfection prediction is assumed. Automatic flight control systems were developed to assess three control strategies for suitability to the carrier landing task. The focus of this assessment was on vertical glide path deviation control. Direct Lift Control was compared to conventional control and was found to have superior performance, especially in turbulence. As UAV planforms tend to be tailless, and therefore lateral and pitch control are generated by a common aerodynamic surface, thrust vectoring was investigated as a means of alleviating aerodynamic pitch control requirements in the carrier landing task. An Adaptive Approach Speed Controller was developed as an extension of the Navigation System. This system synchronises the time that the aircraft passes over the stern, or ramp, of the carrier with the minimum absolute carrier pitch attitude attainable for a given range of approach speeds. This system was shown to be an effective method of minimising the negative effect that carrier motion has on the clearance between the aircraft and the carrier’s ramp
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Flight control system design for autonomous UAV carrier landing
2004Co-Authors: Cook M, Fitzgerald PioAbstract:The challenge of integrating the UAV fleet into the carrier landing Operational Structure with respect to navigation and control strategies is addressed. A simulation model was developed which includes an aircraft model, an atmosphere model and an aircraft carrier motion model. The six degree of freedom non-linear aircraft model is based on the aerodynamic characteristics of the Mk 4a Jindivik extended to include rudder, spoiler and thrust vectoring controls, and an undercarriage model. The atmosphere model includes a carrier landing atmospheric disturbance model. The six degree of freedom aircraft carrier motion model is based on the ship motion simulation program SEAWAY. A Navigation System was developed which conforms to current Operational procedures and future military navigation goals. This Navigation System continuously predicts the position in space where touchdown on the carrier deck will take place, based on aircraft position, the relative velocity between the aircraft and carrier, and the motion time history of the carrier. A reference flight path to the predicted touchdown point is continuously defined. The aircraft deviation from this flight path is determined and input to the autoland control system. For the purposes of this study perfection prediction is assumed. Automatic flight control systems were developed to assess three control strategies for suitability to the carrier landing task. The focus of this assessment was on vertical glide path deviation control. Direct Lift Control was compared to conventional control and was found to have superior performance, especially in turbulence. As UAV planforms tend to be tailless, and therefore lateral and pitch control are generated by a common aerodynamic surface, thrust vectoring was investigated as a means of alleviating aerodynamic pitch control requirements in the carrier landing task. An Adaptive Approach Speed Controller was developed as an extension of the Navigation System. This system synchronises the time that the aircraft passes over the stern, or ramp, of the carrier with the minimum absolute carrier pitch attitude attainable for a given range of approach speeds. This system was shown to be an effective method of minimising the negative effect that carrier motion has on the clearance between the aircraft and the carrier’s ramp.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Ponnurangam Kumaraguru - One of the best experts on this subject based on the ideXlab platform.
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what they do in shadows twitter underground follower market
Conference on Privacy Security and Trust, 2015Co-Authors: Anupama Aggarwal, Ponnurangam KumaraguruAbstract:Internet users and businesses are increasingly using online social networks (OSN) to drive audience traffic and increase their popularity. In order to boost social presence, OSN users need to increase the visibility and reach of their online profile, like — Facebook likes, Twitter followers, Instagram comments and Yelp reviews. For example, an increase in Twitter followers not only improves the audience reach of the user but also boosts the perceived social reputation and popularity. This has led to a scope for an underground market that provides followers, likes, comments, etc. via a network of fraudulent and compromised accounts and various collusion techniques. In this paper, we landscape the underground markets that provide Twitter followers by studying their basic building blocks — merchants, customers and phony followers. We charecterize the services provided by merchants to understand their Operational Structure and market hierarchy. Twitter underground markets can Operationalize using a premium monetary scheme or other incentivized freemium schemes. We find out that freemium market has an oligopoly Structure with few merchants being the market leaders. We also show that merchant popularity does not have any correlation with the quality of service provided by the merchant to its customers. Our findings also shed light on the characteristics and quality of market customers and the phony followers provided by underground market. We draw comparison between legitimate users and phony followers, and find out key identifiers to separate such users. With the help of these differentiating features, we build a supervised learning model to predict suspicious following behaviour with an accuracy of 89.2%.
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what they do in shadows twitter underground follower market
arXiv: Social and Information Networks, 2014Co-Authors: Anupama Aggarwal, Ponnurangam KumaraguruAbstract:Internet users and businesses are increasingly using online social networks (OSN) to drive audience traffic and increase their popularity. In order to boost social presence, OSN users need to increase the visibility and reach of their online profile, like - Facebook likes, Twitter followers, Instagram comments and Yelp reviews. For example, an increase in Twitter followers not only improves the audience reach of the user but also boosts the perceived social reputation and popularity. This has led to a scope for an underground market that provides followers, likes, comments, etc. via a network of fraudulent and compromised accounts and various collusion techniques. In this paper, we landscape the underground markets that provide Twitter followers by studying their basic building blocks - merchants, customers and phony followers. We charecterize the services provided by merchants to understand their Operational Structure and market hierarchy. Twitter underground markets can Operationalize using a premium monetary scheme or other incentivized freemium schemes. We find out that freemium market has an oligopoly Structure with few merchants being the market leaders. We also show that merchant popularity does not have any correlation with the quality of service provided by the merchant to its customers. Our findings also shed light on the characteristics and quality of market customers and the phony followers provided. We draw comparison between legitimate users and phony followers, and find out key identifiers to separate such users. With the help of these differentiating features, we build a supervised learning model to predict suspicious following behaviour with an accuracy of 89.2%.
Donald K Wright - One of the best experts on this subject based on the ideXlab platform.
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Structure and development of the public relations agency industry in the united states Operational Structure clients fees and talent
International Journal of Strategic Communication, 2013Co-Authors: Donald K WrightAbstract:Any examination of the history, dynamics, and role of public relations and communication management consulting would be incomplete without an assessment of the Structure and development of the public relations agency industry. This article provides a detailed look at how public relations is defined, regardless of what it might be called, along an assessment of the history and development of the public relations agency industry in the United States. In addition, the article provides detailed information about the organizational Structure of public relations firms, agency clients, fees charged by these firms, the role played by global holding companies along with an explanation about talent and staffing challenges.
Marc Russell - One of the best experts on this subject based on the ideXlab platform.
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an Operational Structure for clarity in ecosystem service values
Ecological Economics, 2011Co-Authors: Robert J Johnston, Marc RussellAbstract:Analyses used to value ecosystem services often confuse final ecosystem services with ecological functions that provide indirect benefit. Typologies of ecosystem services, such as that developed by the Millennium Ecosystem Assessment, do not ameliorate these challenges. Among the causes of ambiguity in classifying values associated with intermediate versus final ecosystem services are (1) the lack of simple, broadly applicable guidelines to assist natural and social scientists in deriving consistent and replicable classifications, and (2) attempts to define universal typologies of final services that apply to all beneficiaries. This paper presents an Operational mechanism for determining whether a biophysical feature, quantity, or quality represents a final ecosystem service for an inclusive suite of beneficiaries. It is designed for straightforward application by those without expertise in natural or social sciences, and can be used within existing typologies. Illustrations of the Structure demonstrate how the resulting classifications avert double counting and other ambiguities.
Magnus Persson - One of the best experts on this subject based on the ideXlab platform.
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the impact of Operational Structure lateral integrative mechanisms and control mechanisms on intra mne knowledge transfer
International Business Review, 2006Co-Authors: Magnus PerssonAbstract:This study develops and tests a comprehensive framework aimed at explaining outbound knowledge transfer at subsidiary level in multinational enterprises (MNEs). Three groups of influencing factors ...