Search results for "Shield"
showing 10 items of 177 documents
Effects of double ground faults in Wind Farms collector cables
2015
Medium Voltage collector cables of Wind Farms have metal shields connected to the grounding systems of the towers and of the connection station. Thanks to this bonding, when a ground fault occurs, the fault current splits itself among all the grounding systems of the wind farm, this causing a reduction of the ground potential rise at the fault location. Nevertheless, in presence of double ground faults, very high ground potential rises occur at the two fault locations and safety against electric shock is not always assured. In order to study this issue, the paper presents a model for simulating in a simple way the effects of double ground faults occurring in Medium Voltage collectors of ext…
Impact of industrial environments on the PC-based measurements
2007
In the paper we present a simple and fast procedure to evaluate the impact of the electromagnetic disturbances, which can be present in the industrial locations, on the measurements performed by a generic PC-based measurement instrument. The method is conceived starting from the data obtained by subjecting the instruments to the disturbances prescribed by the IEC-61326 standard. The results show that, even under heavy disturbances, the common good practices of shielding and grounding allow a correct employment of this kind of instrumentation.
Influence of LV neutral grounding on global earthing systems
2015
International Standards define a Global Earthing System as an earthing net created interconnecting local Earthing Systems (generally through the shield of MV cables and/or bare buried conductors). In Italy, the regulatory authority for electricity and gas requires distributors to guarantee the electrical continuity of LV neutral conductor. This requirement has led to the standard practice of realizing “reinforcement groundings” along the LV neutral conductor path and at users’ delivery cabinet. Moreover, in urban high-load scenarios (prime candidates to be part of a Global Earthing System), it is common that LV distribution scheme creates, through neutral conductors, an effective connection…
Personal protective equipment and intensive care unit healthcare worker safety in the COVID-19 era (PPE-SAFE): An international survey
2020
Purpose To survey healthcare workers (HCW) on availability and use of personal protective equipment (PPE) caring for COVID-19 patients in the intensive care unit (ICU). Materials and method A web-based survey distributed worldwide in April 2020. Results We received 2711 responses from 1797 (67%) physicians, 744 (27%) nurses, and 170 (6%) Allied HCW. For routine care, most (1557, 58%) reportedly used FFP2/N95 masks, waterproof long sleeve gowns (1623; 67%), and face shields/visors (1574; 62%). Powered Air-Purifying Respirators were used routinely and for intubation only by 184 (7%) and 254 (13%) respondents, respectively. Surgical masks were used for routine care by 289 (15%) and 47 (2%) for…
SARS-CoV-2: Impact on, Risk Assessment and Countermeasures in German Eye Banks.
2020
Introduction Since the beginning of the COVID-19 pandemic there has been some debate regarding the risk of transmission through tissue transplantation and tissue banking processes. Aim of the study To analyze the changes that SARS-CoV-2 has caused regarding the harvesting of corneal donor tissue and eye bank activities in Germany. Methods A questionnaire was provided to 26 eye banks in Germany, consisting of questions about adaptations made in the screening of potential donors and the harvesting of corneal tissue following the pandemic spread of SARS-CoV-2. Results Eighteen eye banks actively reduced recruitment of donors and two banks ceased all activity. Additional diagnostic screening wa…
Radiation leakage study for the Valencia applicators
2011
Abstract Introduction and purpose The Valencia applicators which are accessories of the microSelectron-HDR afterloader (Nucletron, Veenendaal, The Netherlands) are designed to treat skin lesions. These cup-shaped applicators are an alternative to superficial/orthovoltage x-ray treatment units. They limit the irradiation to the required area using tungsten-alloy shielding, and are equipped with a tungsten-alloy flattering filter allowing the treatment of skin tumors, the oral cavity, vaginal cuff, etc. The tungsten-alloy thickness to shield radiation is not the same in all parts of the applicators. This fact led us to question whether the leakage radiation differs depending on where it is me…
First evidence of avian pox-like outbreaks in Eurasian coots, Fulica atra, from Europe: A widespread phenomenon?
2019
Avian pox is a disease caused by Avipoxvirus spp. that is known to produce self-limiting, proliferative epithelial lesions in over 275 bird species from 70 families. Although generally benign, this emerging disease can sometimes provoke significant outbreaks of mortality. In rallids, there is a single serological record of Avipoxvirus. In this study, we report on field evidence for two avian pox-like outbreaks in Eurasian coots, Fulica atra. In Utterslev Mose, Denmark, 17 birds were found in the winter and early spring of 2006 with putative signs of pox-like lesions on the frontal shield and bill. Similar lesions were detected in a population of c. 30 Eurasian coots from a small wetland in…
33S hyperfine interactions in H2S and SO2 and revision of the sulfur nuclear magnetic shielding scale
2014
Using the Lamb-dip technique, the hyperfine structure in the rotational spectra of H2(33)S and (33)SO2 has been resolved and the corresponding parameters--that is, the sulfur quadrupole-coupling and spin-rotation tensors--were determined. The experimental parameters are in good agreement with results from high-level coupled-cluster calculations, provided that up to quadruple excitations are considered in the cluster operator, sufficiently large basis sets are used, and vibrational corrections are accounted for. The (33)S spin-rotation tensor for H2S has been used to establish a new sulfur nuclear magnetic shielding scale, combining the paramagnetic part of the shielding as obtained from the…
Dosimetric perturbations of a lead shield for surface and interstitial high-dose-rate brachytherapy.
2014
In surface and interstitial high-dose-rate brachytherapy with either (60)Co, (192)Ir, or (169)Yb sources, some radiosensitive organs near the surface may be exposed to high absorbed doses. This may be reduced by covering the implants with a lead shield on the body surface, which results in dosimetric perturbations. Monte Carlo simulations in Geant4 were performed for the three radionuclides placed at a single dwell position. Four different shield thicknesses (0, 3, 6, and 10 mm) and three different source depths (0, 5, and 10 mm) in water were considered, with the lead shield placed at the phantom surface. Backscatter dose enhancement and transmission data were obtained for the lead shields…
A generic TG-186 shielded applicator for commissioning model-based dose calculation algorithms for high-dose-rate Ir-192 brachytherapy
2017
PurposeA joint working group was created by the American Association of Physicists in Medicine (AAPM), the European Society for Radiotherapy and Oncology (ESTRO), and the Australasian Brachytherapy Group (ABG) with the charge, among others, to develop a set of well-defined test case plans and perform calculations and comparisons with model-based dose calculation algorithms (MBDCAs). Its main goal is to facilitate a smooth transition from the AAPM Task Group No. 43 (TG-43) dose calculation formalism, widely being used in clinical practice for brachytherapy, to the one proposed by Task Group No. 186 (TG-186) for MBDCAs. To do so, in this work a hypothetical, generic high-dose rate (HDR) Ir-19…