نتایج جستجو برای: such as lightning

تعداد نتایج: 5966108  

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه ولی عصر (عج) - رفسنجان - دانشکده ریاضی 1389

in this thesis, first the notion of weak mutual associativity (w.m.a.) and the necessary and sufficient condition for a $(l,gamma)$-associated hypersemigroup $(h, ast)$ derived from some family of $lesssim$-preordered semigroups to be a hypergroup, are given. second, by proving the fact that the concrete categories, semihypergroups and hypergroups have not free objects we will introduce t...

2009
Vladimir A. Rakov

A review of lightning protection concepts introduced by Benjamin Franklin (18th century) and James Clerk Maxwell (19th century) is given. Modern approaches to lightning protection of various structures and systems are discussed. In particular, the widely used electrogeometrical model (one version of which is the Rolling Sphere Method) and the topological shielding are presented. Bonding require...

2010
A. Lafkovici

The North American Lightning Detection Network (NALDN) is a commercial lightning detection network composed of the U.S. National Lightning Detection Network (NLDN) and the Canadian Lightning Detection Network (CLDN). The NALDN was developed to provide lightning information by accurately detecting and locating most cloud-to-ground (CG) lightning strokes and a small fraction of discharges produce...

2010
U. S. Inan S. A. Cummer R. A. Marshall

[1] Extremely low frequency (ELF) and very low frequency (VLF) observations have formed the cornerstone of measurement and interpretation of effects of lightning discharges on the overlying upper atmospheric regions, as well as near‐Earth space. ELF (0.3–3 kHz) and VLF (3–30 kHz) wave energy released by lightning discharges is often the agent of modification of the lower ionospheric medium that...

2016
Ilaria Bendato Massimo Brignone Federico Delfino Farhad Rachidi Vernon Cooray

The estimation of the lightning performance of a power distribution network is of great importance to design its protection system against lightning. An accurate evaluation of the number of lightning events that can create dangerous overvoltages requires a huge computational effort, as it implies the adoption of a Monte Carlo procedure. Such a procedure consists of generating many different ran...

پایان نامه :دانشگاه آزاد اسلامی - دانشگاه آزاد اسلامی واحد تهران مرکزی - دانشکده ادبیات و علوم انسانی 1390

abstract birbery and corruption and other criminal and as such is one of social phenomena , and i can firmly say that society is protected and safe from harm , this is criminal . eache community is familiar with these crimes and the crime associated ( direct or indirect ) with the political economic , social , and cultural beliefs and religious issues , especially with the community . admitted...

2013
Amos Necci Giacomo Antonioni Valerio Cozzani Alberto Borghetti Carlo Alberto Nucci

Several accidents that occurred in the last decades evidenced that the impact of natural events in industrial plants may trigger accidental scenarios involving the release of relevant quantities of hazardous substances. Severe scenarios typical of the process industry, as fires, explosions, toxic releases, and water pollution were reported as the consequence of natural events in industrial area...

2006
Aram Faghfouri

Electric power utilities face increasing demand for service reliability. Since cloud-toground lightning strikes are among the most frequent yet least understood causes of service interruption, predicting the geographical and temporal distribution of the lightning strikes can help power system planners and designers improve the protection of new and existing transmission lines. Lightning is the ...

تدین رودی, پویا , شریعتی‌نسب, رضا ,

This paper presents a new method, based on analytical relations and Monte Carlo simulation for calculating the lightning performance of overhead lines caused by direct strokes. The aim of the work is to reduce the computing time together with retaining enough accuracy to estimate the line lightning performance and performing the risk analysis of power networks. In the proposed method, some modi...

2017
Li Zhang Guozheng Wang Wenfang Zhang Yufei Ma Zixin Guo Qingmin Li

Wind turbine blades being struck by lightning is one of the most urgent problems facing wind farms. In order to reduce the probability of lightning accidents on wind farms, this paper presents a new electro-geometric model for multiple turbines. In this new model, based on the physical model of lightning leader development, the striking distance range of the blade tip receptor is calculated, ta...

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