Thermionic noise measurements for on-line dispenser cathode diagnostics for linear beam microwave tubes

A test stand has been set up to measure the current fluctuation noise properties of B- and M-type dispenser cathodes in a typical TWT gun structure. Noise techniques were used to determine the work function distribution on the cathode surfaces. Significant differences between the B and M types and significant changes in the work function distribution during activation and life are found. In turn, knowledge of the expected work function can be used to accurately determine the cathode-operating temperatures in a TWT structure. Noise measurements also demonstrate more sensitivity to space charge effects than the Miram method. Full automation of the measurements and computations is now required to speed up data acquisition and reduction. The complete set of equations for the space charge limited diode were programmed so that given four of the five measurable variables (J, J sub O, T, D, and V) the fifth could be computed. Using this program, we estimated that an rms fluctuation in the diode spacing d in the frequency range of 145 Hz about 20 kHz of only about 10 to the -5 power A would account for the observed noise in a space charge limited diode with 1 mm spacing

A proposed remote manipulator system: A concept

System is described with variable ratio, mixed mode, bilateral, master-slave control. Manipulator arms consist of shoulder and elbow with two degrees of freedom, a wrist with three degrees of freedom, and terminal grasping device. Feedback is provided by TV cameras attached near shoulder, grasping device, and at end of shuttle opposite arm

The early Cycladic settlement at Dhaskalio, Keros: preliminary report of the 2008 excavation season

The 2008 excavations on the small island of Dhaskalio opposite Dhaskalio Kavos on the Cycladic island of Keros are reviewed. An account is given of the survey, recording many walls of the early Bronze Age, and of the excavations, continued from the 2007 season. Excavations at the summit of Dhaskalio revealed a substantial building 16 m long and 4 m wide, within which was discovered the ‘Dhaskalio hoard’ comprising a chisel, an axe-adze, and a shaft-hole axe of copper or bronze. Study of the pottery reveals continuity, within which a sequence of three phases within the Early Cycladic II and III periods can be established. Excavations were continued and concluded within the Special Deposit at Kavos South with the recovery of many more special but fragmentary materials including marble vessels and figurines. Specialist studies for the geomorphology, geology, petrology, ceramic petrology, metallurgy and environmental aspects (botanical and faunal remains, phytoliths) are in progress. No more fieldwork is planned prior to final publication of the 2006 to 2008 seasons

A manipulator arm for zero-g simulations

A 12-ft counterbalanced Slave Manipulator Arm (SMA) was designed and fabricated to be used for resolving the questions of operational applications, capabilities, and limitations for such remote manned systems as the Payload Deployment and Retrieval Mechanism (PDRM) for the shuttle, the Free-Flying Teleoperator System, the Advanced Space Tug, and Planetary Rovers. As a developmental tool for the shuttle manipulator system (or PDRM), the SMA represents an approximate one-quarter scale working model for simulating and demonstrating payload handling, docking assistance, and satellite servicing. For the Free-Flying Teleoperator System and the Advanced Tug, the SMA provides a near full-scale developmental tool for satellite servicing, docking, and deployment/retrieval procedures, techniques, and support equipment requirements. For the Planetary Rovers, it provides an oversize developmental tool for sample handling and soil mechanics investigations. The design of the SMA was based on concepts developed for a 40-ft NASA technology arm to be used for zero-g shuttle manipulator simulations

On ‘Organized Crime’ in the illicit antiquities trade: moving beyond the definitional debate

The extent to which ‘organized crime’ is involved in illicit antiquities trafficking is unknown and frequently debated. This paper explores the significance and scale of the illicit antiquities trade as a unique transnational criminal phenomenon that is often said to be perpetrated by and exhibit traits of so-called ‘organized crime.’ The definitional debate behind the term ‘organized crime’ is considered as a potential problem impeding our understanding of its existence or extent in illicit antiquities trafficking, and a basic progression-based model is then suggested as a new tool to move beyond the definitional debate for future research that may help to elucidate the actors, processes and criminal dynamics taking place within the illicit antiquities trade from source to market. The paper concludes that researchers should focus not on the question of whether organized criminals- particularly in a traditionally conceived, mafia-type stereotypical sense- are involved in the illicit antiquities trade, but instead on the structure and progression of antiquities trafficking itself that embody both organized and criminal dynamics

Requirements engineering for intelligent environments

The field of Intelligent Environments (IE) is maturing to a level at which a range of sophisticated applications are emerging. Such systems aim to be context-aware, especially being adaptable to possibly unpredictable circumstances. An area of significant potential is that of ‘ambient assisted living’, with significant advances in fields such as smart spaces, classrooms, and assisted living space for the elderly or people with disabilities. In recent years, however, it has been recognised that numerous IE systems have been developed without adopting best practises from software engineering. The work presented here focuses on the requirements engineering stage and presents a framework for IE systems in which an intrinsic component is context-awareness. Whilst the framework is intended as a general IE model, we are currently applying it to the specific area of ambient assisted living and it is being employed on the POSEIDON project. It is anticipated that such real world application of the model will help endorse its conception and facilitate further refinement of the framework