Experimental Investigations on the Pulsed Power Switch of a HIRA based UWB System

The Ultra Wide Band (UWB) system has been a subject of research in the last few years due to its utility in various high power electromagnetic applications. Due to its simplicity in design and fabrication, the Half Impulse Radiating Antenna (HIRA) based UWB system has attracted many researchers. Effectiveness of a UWB system, in terms of the bandwidth of the radiated pulse depends on the duration of the radiated field which is typically of sub nanosecond regime. This duration in turn depends on the closure time of the switch used in the UWB pulsed power source. This paper presents the work carried out on the pressurised gas switch of a 50 kV pulsed power system of a HIRA based UWB system. The aim of the present work is to establish the relationship between the pulser switch breakdown voltage and gas pressure, rise time and gas pressure as well as the dependency of the Pulse Repetition Rate (PRR) on the switch breakdown voltage.

Electromagnetic Shielding Properties of Nano Carbon Filled Silicone Rubber Composites

Electromagnetic shielding has become important for various electrical systems because of the electromagnetic pollution caused by the large scale use of electronic devices operating at different frequencies and power levels. Traditionally used metallic shields lack flexibility and hence may not be the right choice for certain applications. In such situations, filled polymer composites provide a good alternative for electromagnetic shielding applications. Being polymer based, they are easy to manufacture and can be molded into the required geometry and shape. In this study, the shielding properties of multiwalled carbon nanotubes and carbon nanofibers filled silicone rubber are studied. The conductivity and the shielding effectiveness of the composites were measured at different filler loadings. Both the fillers are able to make the base polymer conducting even at very low filler loadings. The conductivity and the shielding effectiveness improved when the filler loading was above the percolation threshold.

Numerical analysis of the settlement induced damage to Palazzo Loggia in Brescia

One of the main causes of failure of historic buildings is represented by the differential settlements of foundations. Finite element analysis provides a useful tool for predicting the consequences of given ground displacements in terms of structural damage and also assesses the need of strengthening techniques. The actual damage classification for buildings subject to settlement bases the assessment of the potential damage on the expected crack pattern of the structure. In this paper, the correlation between the physical description of the damage in terms of crack width and the interpretation of the finite element analysis output is analyzed. Different discrete and continuum crack models are applied to simulate an experiment carried on a scale model of a masonry historical building, the Loggia Palace in Brescia (Italy). Results are discussed and a modified version of the fixed total strain smeared crack model is evaluated, in order to solve the problem related to the calculation of the exact crack width.

Coulomb blockade double-dot Aharonov-Bohm interferometer: Giant fluctuations

Electron transport through two parallel quantum dots is a kind of solid-state realization of double path interference We demonstrate that the inter-clot Coulomb correlation and quantum coherence would result in strong current fluctuations with a divergent Fano factor at zero frequency. We also provide physical interpretation for this surprising result, which displays its generic feature and allows us to recover this phenomenon in more complicated systems. (C) 2009 Elsevier B.V. All rights reserved.

"My" i "oni", "swój" i "obcy". Bałkany XX wieku z perspektywy kolonialnej i postkolonialnej

W artykule został przeanalizowany dyskurs bałkański XX wieku z kolonialnego i postkolonialnego punktu widzenia. Pierwsza część przybliża geopolityczny stosunek do Bałkanów,The Balans in the Gaze of Western Travellers (2004) jako przykłady korygującego wobec istniejących dotychczas reprezentacji i wyobrażeń Bałkanów. skupia się jednak nie tylko na nazwie geograficznej Półwysep Bałkański, lecz przede wszystkim na figuratywnym i metaforycznym języku, bazującym na stereotypach i negatywnych „etykietkach” Bałkanów, takich jak: „beczka prochu”, obszar „zadawnionej nienawiści”, „zderzenie cywilizacji”, „strefa rozłamu”, europejskie „jądro ciemności”, „dzika Europa”, „jeszcze- nie” Europa. Ten stosunek opiera się na opozycji My-Oni z kolonialnego, punktu widzenia Zachodu. W drugiej części tekstu zostaje przeprowadzona analiza trzech utworów prozatorskich autorstwa wybitnych pisarzy z Bałkanów – chorwacki dyskurs literacki jest reprezentowany przez Miroslava Krležę w opowiadaniu W Dreźnie. Mister Wu San Pej interesuje się problemem serbsko-chorwackim (1924), serbski dyskurs przedstawia Ivo Andrić w opowiadaniu List z roku 1920 (1946), natomiast bośniacki – Nenad Veličković i jego powieść epistolarna Sahib. Impresje z depresji (2001). Te trzy dyskursy z różnych przełomowych dla Jugosławii okresów pokazują, że pisarze chętnie sięgali po figurę „Obcego”, by uwypuklić problemy związane z własną złożoną, często zwielokrotnioną tożsamością. Ostatnia część akcentuje nowe, postkolonialne podejście do problemu Bałkanów – uczestniczą w nim wybitni naukowcy pochodzący z tego regionu, którzy zrobili kariery w Europie Zachodniej i USA. W tej części zostają zaprezentowane trzy fundamentalne dla tego problemu książki – studium Marii Todorowej (Bułgarka) Imagining the Balkans (1997), monografia Vesny Bjelogrlić-Goldsworthy (Serbka) Inventing Ruritania: The Imperializm of the Imagination (1998) oraz antropologiczna książka Božidara Jezernika (Słoweniec) Wild Europe.

Hybrid energy storage for energy harvesting powered wireless sensor networks

Science Foundation Ireland (CSET - Centre for Science, Engineering and Technology, grant 07/CE/I1147); Scientific Foundation Ireland (ITOBO (398-CRP))