MIB for the UDP-Lite Protocol

Publisher PD

Enhancing the decision-making process of project managers in the built environment: An integrated approach

A study of the project manager’s (PM) function must be to examine: what their role is, their skills, and training needed. The project manager needs wide perspective regarding the classic management functions of control, coordination, communication, and the settling of performance standards. If the PM is a professional, their performance must be of the highest standard, and must be accountable for a high level of productivity. This is the project manager’s Achilles heel. Another problem is the absence of feedback during the early stages through to completion of the project. During the project’s life the relative importance of their responsibilities may change several times, including the constant changing of the dynamic environment. The PM will aim for a balanced emphasis; they will try to be flexible so they can adapt to new circumstances as they occur. The PM needs tried and tested methods to aid his decision making. This paper posits an integrated development and use of methods such as; scenario planning, effectuation, and reflective thinking to enhance decision making. The paper concludes with potential benefits that this method brings to the PM when fully understood and tested in the application domain

Flexible conformable hydrophobized surfaces for turbulent flow drag reduction

In recent years extensive work has been focused onto using superhydrophobic surfaces for drag reduction applications. Superhydrophobic surfaces retain a gas layer, called a plastron, when submerged underwater in the Cassie-Baxter state with water in contact with the tops of surface roughness features. In this state the plastron allows slip to occur across the surface which results in a drag reduction. In this work we report flexible and relatively large area superhydrophobic surfaces produced using two different methods: Large roughness features were created by electrodeposition on copper meshes; Small roughness features were created by embedding carbon nanoparticles (soot) into Polydimethylsiloxane (PDMS). Both samples were made into cylinders with a diameter under 12 mm. To characterize the samples, scanning electron microscope (SEM) images and confocal microscope images were taken. The confocal microscope images were taken with each sample submerged in water to show the extent of the plastron. The hydrophobized electrodeposited copper mesh cylinders showed drag reductions of up to 32% when comparing the superhydrophobic state with a wetted out state. The soot covered cylinders achieved a 30% drag reduction when comparing the superhydrophobic state to a plain cylinder. These results were obtained for turbulent flows with Reynolds numbers 10,000 to 32,500

Improved source localization with LIGO India

A global network of advanced gravitational wave interferometric detectors is under construction. These detectors will offer an order of magnitude improvement in sensitivity over the initial detectors and will usher in the era of gravitational wave astronomy. In this paper, we evaluate the benefits of relocating one of the advanced LIGO detectors to India.Comment: 7 pages, 3 figures, accepted for publication in proceedings of ICGC2011 conference. Localization figures update

Robust spatially resolved pressure measurements using MRI with novel buoyant advection-free preparations of stable microbubbles in polysaccharide gels

MRI of fluids containing lipid coated microbubbles has been shown to be an effective tool for measuring the local fluid pressure. However, the intrinsically buoyant nature of these microbubbles precludes lengthy measurements due to their vertical migration under gravity and pressure-induced coalescence. A novel preparation is presented which is shown to minimize both these effects for at least 25 min. By using a 2% polysaccharide gel base with a small concentration of glycerol and 1,2-distearoyl-sn-glycero-3-phosphocholine coated gas microbubbles, MR measurements are made for pressures between 0.95 and 1.44 bar. The signal drifts due to migration and amalgamation are shown to be minimized for such an experiment whilst yielding very high NMR sensitivities up to 38% signal change per bar

Toward 'socially constructive' social constructions of leadership

In their introductory editorial essay for this special issue, David Grant and Gail Fairhurst have done us a great service by valiantly producing a "Sailing Guide" to the Social Construction of Leadership (Fairhurst & Grant, 2010). As with rounding the Capes, this is not a task for the faint of heart. A sailing guide is designed to provide vital knowledge about a particular sea or coast, providing us with charts, warnings about potential hazards and an indication where we might find safe havens in a storm. Their sailing guide does this to great effect as it skilfully "boxes the compass" by revealing all of the potential directions that one might set one‟s sail by if one was sufficiently foolhardy to embark on a cruise of the social construction of leadership

A cross-layer architecture for satellite network security: CL-IPsec

Cross-layer architectures (CLAs) are proposed to improve performance in networks where physical layer impairments are unpredictable and provision of security services may be challenging, as in satellite networks. This paper proposes an extension to the IPsec protocol, named Cross-Layer IPsec (CL-IPsec), able to provide authentication and integrity services through a cross-layer architecture when the adopted protocol is UDP-Lite. This is suitable for multicast applications that are cost-effectively provided by satellite systems. A satellite emulation platform has been used to validate the CL-IPsec implementation and to evaluate the performance improvement derived from the proposed CLA. © 2008 IEEE

Network layer security: Design for a cross layer architecture

Traditional modular layering schemes have served a major part in the development of a variety of protocols. However, as the physical layer impairments become more unpredictable, a cross layer design (CLD) which is dynamic in nature provides better performance. CLD introduces new challenges in protocol design as well as in the area of security. Using numerical analysis, we show that a link layer design employing header compression and cross layer signalling to protect protocol headers can limit packet discarding. This paper also reviews the IPsec protocol and describes how IPsec can be modified for cross layer architecture. © 2007 IEEE

Considerations around transport header confidentiality, network operations, and the evolution of Internet transport protocols

To protect user data and privacy, Internet transport protocols have supported payload encryption and authentication for some time. Such encryption and authentication are now also starting to be applied to the transport protocol headers. This helps avoid transport protocol ossification by middleboxes, mitigate attacks against the transport protocol, and protect metadata about the communication. Current operational practice in some networks inspect transport header information within the network, but this is no longer possible when those transport headers are encrypted. This document discusses the possible impact when network traffic uses a protocol with an encrypted transport header. It suggests issues to consider when designing new transport protocols or features

Painless Obstructive Jaundice Secondary to a Common Bile Duct Abscess: A Delayed Sequela of Cholecystectomy

Complications related to cholecystectomy are well described. Most occur in the early postoperative period and are recognised either at the time of, or shortly after surgery. Clinical sequelae occurring years following cholecystectomy are rare and infrequently reported. In addition, most delayed complications are related to the continuing presence or new formation of gallstones. In this paper we present a unique case of an abscess of the common bile duct wall, presenting with painless obstructive jaundice more than 30 years following an open cholecystectomy, without the presence of gallstones. The clinical presentation, investigations, and treatment are discussed with a review of other relevant reported cases in the literature