Topological analysis of the power grid and mitigation strategies against cascading failures

This paper presents a complex systems overview of a power grid network. In recent years, concerns about the robustness of the power grid have grown because of several cascading outages in different parts of the world. In this paper, cascading effect has been simulated on three different networks, the IEEE 300 bus test system, the IEEE 118 bus test system, and the WSCC 179 bus equivalent model, using the DC Power Flow Model. Power Degradation has been discussed as a measure to estimate the damage to the network, in terms of load loss and node loss. A network generator has been developed to generate graphs with characteristics similar to the IEEE standard networks and the generated graphs are then compared with the standard networks to show the effect of topology in determining the robustness of a power grid. Three mitigation strategies, Homogeneous Load Reduction, Targeted Range-Based Load Reduction, and Use of Distributed Renewable Sources in combination with Islanding, have been suggested. The Homogeneous Load Reduction is the simplest to implement but the Targeted Range-Based Load Reduction is the most effective strategy.Comment: 5 pages, 8 figures, 1 table. This is a limited version of the work due to space limitations of the conference paper. A detailed version is submitted to the IEEE Systems Journal and is currently under revie

The LSE identity project. House of Lords : All party briefing : "Nothing to hide, nothing to fear”

The original amendment on cost information, put forward in the House of Lords, sought to address a widely held concern about the government’s unwillingness to be open about the likely costs associated with implementing the identity cards scheme. These concerns are shared by some in the Lords, industry and by the LSE, whose initial alternative costings fuelled the concerns of the Lords over the limited information made available to them. The proposed amendment for the House of Commons does not seek to address this underlying issue and, indeed, the provisions of clause 4, are likely to repeat the same, unnecessary secrecy that the Lords were seeking to explore

A novel interplanetary communications relay

A case study of a potential Earth-Mars interplanetary communications relay, designed to ensure continuous communications, is detailed. The relay makes use of orbits based on artificial equilibrium points via the application of continuous low thrust, which allows a spacecraft to hover above the orbital plane of Mars and thus ensure communications when the planet is occulted with respect to the Earth. The artificial equilibria of two different low-thrust propulsion technologies are considered: solar electric propulsion, and a solar sail/solar electric propulsion hybrid. In the latter case it is shown that the combination of sail and solar electric propulsion may prove advantageous, but only under specific circumstances of the relay architecture suggested. The study takes into account factors such as the spacecraft's power requirements and communications band utilized to determine the mission and system architecture. A detailed contingency analysis is considered for recovering the relay after increasing periods of spacecraft motor failure, and combined with a consideration for how best to deploy the relay spacecraft to maximise propellant reserves and mission duration

Development of a spectroscopic diagnostic tool for electric field measurements in IShTAR (Ion cyclotron Sheath Test ARrangement)

International audienceIShTAR, Ion cyclotron Sheath Test ARrangement, is a linear device dedicated to the investigation of the edge plasma-ICRF (Ion Cyclotron Range of Frequencies) antenna interactions in tokamak edge-like conditions and serves as a platform for a diagnostic development for measuring the electric fields in the vicinity of ICRF antennas. We present here our progress in the development of an optical emission spectroscopy method for measuring the electric fields which concentrates on the changes in the helium spectral line profiles introduced by the external electrical field, i.e., the Stark effect. To be able to fully control the operating parameters, at the first stage of the study, the measurements are conducted on a planar electrode installed in the centre of the plasma column in IShTAR's helicon plasma source. At the second stage, the measurements are performed in the vicinity of IShTAR's ICRF antenna

DIDET: Digital libraries for distributed, innovative design education and teamwork. Final project report

The central goal of the DIDET Project was to enhance student learning opportunities by enabling them to partake in global, team based design engineering projects, in which they directly experience different cultural contexts and access a variety of digital information sources via a range of appropriate technology. To achieve this overall project goal, the project delivered on the following objectives: 1. Teach engineering information retrieval, manipulation, and archiving skills to students studying on engineering degree programs. 2. Measure the use of those skills in design projects in all years of an undergraduate degree program. 3. Measure the learning performance in engineering design courses affected by the provision of access to information that would have been otherwise difficult to access. 4. Measure student learning performance in different cultural contexts that influence the use of alternative sources of information and varying forms of Information and Communications Technology. 5. Develop and provide workshops for staff development. 6. Use the measurement results to annually redesign course content and the digital libraries technology. The overall DIDET Project approach was to develop, implement, use and evaluate a testbed to improve the teaching and learning of students partaking in global team based design projects. The use of digital libraries and virtual design studios was used to fundamentally change the way design engineering is taught at the collaborating institutions. This was done by implementing a digital library at the partner institutions to improve learning in the field of Design Engineering and by developing a Global Team Design Project run as part of assessed classes at Strathclyde, Stanford and Olin. Evaluation was carried out on an ongoing basis and fed back into project development, both on the class teaching model and the LauLima system developed at Strathclyde to support teaching and learning. Major findings include the requirement to overcome technological, pedagogical and cultural issues for successful elearning implementations. A need for strong leadership has been identified, particularly to exploit the benefits of cross-discipline team working. One major project output still being developed is a DIDET Project Framework for Distributed Innovative Design, Education and Teamwork to encapsulate all project findings and outputs. The project achieved its goal of embedding major change to the teaching of Design Engineering and Strathclyde's new Global Design class has been both successful and popular with students

Safer clinical systems : interim report, August 2010

Safer Clinical Systems is the Health Foundation’s new five year programme of work to test and demonstrate ways to improve healthcare systems and processes, to develop safer systems that improve patient safety. It builds on learning from the Safer Patients Initiative (SPI) and models of system improvement from both healthcare and other industries. Learning from the SPI highlighted the need to take a clinical systems approach to improving safety. SPI highlighted that many hospitals struggle to implement improvement in clinical areas due to inherent problems with support mechanisms. Clinical processes and systems, rather than individuals, are often the contributors to breakdown in patient safety. The Safer Clinical Systems programme aimed to measure the reliability of clinical processes, identify defects within those processes, and identify the systems that result in those defects. Methods to improve system reliability were then to be tested and re-developed in order to reduce the risk of harm being caused to patients. Such system-level awareness should lead to improvements in other patient care pathways. The relationship between system reliability and actual harm is challenging to identify and measure. Specific, well-defined, small-scale processes have been used in other programmes, and system reliability has been shown to have a direct causal relationship with harm (e.g. care bundle compliance in an intensive care unit can reduce the incidence of ventilator-associated pneumonia). However, it has become evident that harm can be caused by a variety of factors over time; when working in broader, more complex and dynamic systems, change in outcome can be difficult to attribute to specific improvements and difficulties are also associated with relating evidence to resulting harm. The overall aim of Phase 1 of the Safer Clinical Systems programme was to demonstrate proof-of-concept that using a systems-based approach could contribute to improved patient safety. In Phase 1, experienced NHS teams from four locations worked together with expert advisers to co-design the Safer Clinical Systems programme

Autonomous weapon systems and international humanitarian law: a reply to the critics

In November 2012, Human Rights Watch, in collaboration with the International Human Rights Clinic at Harvard Law School, released Losing Humanity: The Case against Killer Robots.[2] Human Rights Watch is among the most sophisticated of human rights organizations working in the field of international humanitarian law. Its reports are deservedly influential and have often helped shape application of the law during armed conflict. Although this author and the organization have occasionally crossed swords,[3] we generally find common ground on key issues. This time, we have not. “Robots” is a colloquial rendering for autonomous weapon systems. Human Rights Watch’s position on them is forceful and unambiguous: “[F]ully autonomous weapons would not only be unable to meet legal standards but would also undermine essential non-safeguards for civilians.”[4] Therefore, they “should be banned and . . . governments should urgently pursue that end.”[5] In fact, if the systems cannot meet the legal standards cited by Human Rights Watch, then they are already unlawful as such under customary international law irrespective of any policy or treaty law ban on them.[6] Unfortunately, Losing Humanity obfuscates the on-going legal debate over autonomous weapon systems. A principal flaw in the analysis is a blurring of the distinction between international humanitarian law’s prohibitions on weapons per se and those on the unlawful use of otherwise lawful weapons.[7] Only the former render a weapon illegal as such. To illustrate, a rifle is lawful, but may be used unlawfully, as in shooting a civilian. By contrast, under customary international law, biological weapons are unlawful per se; this is so even if they are used against lawful targets, such as the enemy’s armed forces. The practice of inappropriately conflating these two different strands of international humanitarian law has plagued debates over other weapon systems, most notably unmanned combat aerial systems such as the armed Predator. In addition, some of the report’s legal analysis fails to take account of likely developments in autonomous weapon systems technology or is based on unfounded assumptions as to the nature of the systems. Simply put, much of Losing Humanity is either counter-factual or counter-normative. This Article is designed to infuse granularity and precision into the legal debates surrounding such weapon systems and their use in the future “battlespace.” It suggests that whereas some conceivable autonomous weapon systems might be prohibited as a matter of law, the use of others will be unlawful only when employed in a manner that runs contrary to international humanitarian law’s prescriptive norms. This Article concludes that Losing Humanity’s recommendation to ban the systems is insupportable as a matter of law, policy, and operational good sense. Human Rights Watch’s analysis sells international humanitarian law short by failing to appreciate how the law tackles the very issues about which the organization expresses concern. Perhaps the most glaring weakness in the recommendation is the extent to which it is premature. No such weapons have even left the drawing board. To ban autonomous weapon systems altogether based on speculation as to their future form is to forfeit any potential uses of them that might minimize harm to civilians and civilian objects when compared to other systems in military arsenals

Communications for underwater robotics research platforms

This paper presents a distributed protocol for communication among autonomous underwater vehicles. It is a complementary approach for coordination between the autonomous underwater vehicles. This paper mainly describes different methods for underwater communication. One of the methods is brute force approach in which messages are broadcasted to all the communication nodes, which in turn will broadcast the acknowledgement. Issues relating to this brute force approach are time delay, number of hops, power consumption, message collision and other practical issues. These issues are discussed and solved by proposing a new method to improve efficiency of this proposed approach and its effectiveness in communication among autonomous underwater vehicles.<br /