98,415 research outputs found
Formation stabilization of underwater mobile sensing networks
No full textFormation control is essential for an underwater mobile sensing network (UMSN), an ad hoc network which wirelessly connects underwater vehicles of sensing and/or observing types via acoustic communications, to fulfill mobile sensing tasks. The problem of formation stabilization for an UMSN with varying communication topology is studied in this paper. Sufficient condition of formation stability is proposed in terms of stability analysis of linear time varying system and spectrum analysis of graph Laplacian of communication topology. Moreover, a design procedure for synthesis of formation controller is given
Evaluation of the effects of the communication cable on the dynamics of an underwater flight vehicle
No full textThis paper presents a numerical scheme to evaluate the effects of the communication cable attached to an underwater flight vehicle. Both simulation and model validation results show that the numerical scheme is effective and provides a means for developing a feed-forward controller to compensate for the cable effects when developing an autopilot for the tethered vehicle. Moreover, the numerical scheme can also be applied to predict the effects of the ROVs umbilical during its deployment. <br/
Reduced-order H? control of an autonomous underwater vehicle
No full textIt is well known that the reduced-order (least-order) H? control problem is a rank minimization problem subject to linear matrix inequality (LMI) constraints which is hard to solve due to the non-convexity of the objective and the trace heuristic is simple and efficient one among various heuristics that approximate the rank minimization problem. In this paper, a theoretical insight into the trade-off between the controller order and the performance of the closed-loop system is given. Autopilots (forward speed, heading and depth) for an autonomous underwater vehicle are synthesized based upon the trace heuristic. Simulation results as well as experimental results of heading control show that the reduced-order autopilots are desirable for practical implementation due to their simple structures and slight performance degradation
Robust control of autonomous underwater vehicles and verification on a tethered flight vehicle
No full textScope: Unmanned marine vehicles (UMVs) include autonomous underwater vehicles, remotely operated vehicles, semi-submersibles and unmanned surface craft. Considerable importance is being placed on the design and development of such vehicles as they provide cost effective solutions to a number of littoral, coastal and offshore problems. This new book highlights the advanced technology which is evolving to meet the challenges being posed in this exciting and growing area of research.Contents: Navigation, Guidance and Control of Unmanned Marine Vehicles. Nonlinear Modelling, Identification and Control of UUVs. Guidance Laws, Obstacle Avoidance and Artificial Potential Functions. Behaviour Control of UUVs. Thruster Control Allocation for Over-Actuated, Open Frame Underwater Vehicles. Switching-Based Supervisory Control of Underwater Vehicles. Navigation, Guidance and Control of the Hammerhead Autonomous Underwater Vehicle. Robust Control of Autonomous Underwater Vehicles and its Verification on a Tethered Flight Vehicle. Low-Cost High Precision Motion Control for ROV’s. Autonomous Manipulation for an Intervention AUV. AUV ‘r2D4’, its operation, and Road Map for AUV Development. Guidance & Control of a Biomimetic-Autonomous Underwater Vehicle. Seabed-Relative Navigation by Hybrid Structured Lighting. Advances in Real-Time Spatio-Temporal 3D Visualisation for Underwater Robotic Exploration. Unmanned Surface Vehicles - Game Changing Technology for Naval Operations. Modelling, Simulation and Control of an Autonomous Surface Marine Vehicle for Surveying Applications Measuring Dolphin MESSIN. Vehicle and Mission Control of Single and Multiple Autonomous Marine Robots. Wave-Piercing Autonomous Vehicles. Dynamics, Control and Coordination of Underwater Gliders.<br/
The Benefits of Being Economics Professor A (and not Z)
No full textAlphabetic name ordering on multi-authored academic papers, which is the convention in the economics discipline and various other disciplines, is to the advantage of people whose last name initials are placed early in the alphabet. As it turns out, Professor A, who has been a first author more often than Professor Z, will have published more articles and experienced afaster growth rate over the course of her career as a result of reputation and visibility. Moreover, authors know that name ordering matters and indeed take ordering seriously: Several characteristics of an author group composition determine the decision to deviate from the default alphabetic name order to a significant extent.performance measurement, incentives, economists, name ordering
Final word on Jersey Dutch
No full textIn this article, William Z. Shetter compares and contrasts the dialects that developed between different Dutch colonies in the New World. He explores in-depth the nuances of Jersey Dutch, and provides theories to explain how Dutch and colonial languages blended. The article is reprinted from American Speech, December 1958, Volum XXXIII, No. 4
Allen, Charles
No full textBlack and white photograph shows Biology professor Charles Allen (left) in a suit and tie and an unidentified woman in a dress, both standing on either side of a Steinway & Sons grand piano, on the Wait Chapel stage. The back of the photograph reads "Left: Charlie Allen, Biology.
Advocating a utilitarian profession in a Kantian world? LIS ethical reflection and the challenges of political philosophy
No full textThe over-arching political philosophy of the past 30 years has seen a movement from the Utilitarian principles that had dominated since the mid to late Victorian period to a more Kantian, rights-based approach to justification of public services and professions. Political philosophy has a major impact on the ethical parameters in which professions operate. In publically-funded libraries a change in such philosophy can alter the aims and objectives of the organisation, and even the justification for its very existence. In a sector that grew out of the Utilitarian era, such as public libraries, old arguments for advocacy that have been used historically hold little sway with elected officials and managers inculcated within a rights-based framework. LIS professional education rarely fills such gaps; while many LIS courses contain modules that deal in professional ethics, a key tangential issue is the understanding of political philosophy and the motivations and beliefs of those who fund library services. Conversely many elected officials come to public service with an education that covers the broadest range of political philosophy. In the UK, North America and Europe, for instance, the PPE degree (politics, philosophy, and economics) and its variants are a staple of the ruling classes. Such a background sees them well able to understand and be able to rebut any arguments for justifying services that do not fit into the rights-based approach. LIS professionals’ ethical reflection must become more strategic and be aimed at advocacy that is effective and will be understood by elected officials influenced by rights-based arguments. Utilising the public library service as an example, this paper will identify how many in the profession may have strategically misfired in terms of their advocacy approach, and instead suggest how ethical reflection could be enhanced by presenting the justification of library services within the philosophical context of the day, and how in doing so fill a major gap in the knowledge of many library and information professionals. It will be argued that used in partnership with ethical codes, such a focused ethical reflection can take such static documents and apply them to myriad real scenarios, enabling them to become a living embodiment of active ethical reflection in library and information services
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