نتایج جستجو برای: high frequency sources
تعداد نتایج: 2604834 فیلتر نتایج به سال:
background: while the use of herbal medicines is common in tehran, there is scant data regarding various aspects of the use of such medicines during pregnancy. objective: the frequency of the use of herbal medicines in a group of pregnant women in tehran and their attitude to the use of such medicines were evaluated. methods: in this cross-sectional study, 600 pregnant women were studied. a res...
There is a persistent shortage of underrepresented minority (URM) faculty who are involved in basic biomedical research at medical schools. We examined the entire training pathway of potential candidates to identify the points of greatest loss. Using a range of recent national data sources, including the National Science Foundation's Survey of Earned Doctorates and Survey of Doctoral Recipients...
A comprehensive analysis of high frequency (100-200 GHz) and high power (> 100 kW) gyrotrons has been conducted. It is shown that high frequencies will be required in order for electron cyclotron radiation to propagate to the center of a compact tokamak power reactor. High power levels will be needed in order to ignite the plasma with a reasonable number of gyrotron units. In the first part of ...
The research results indicated that wet and dry dust deposition is a function of geographical characteristics. The seasonal wet and dry dust deposition and Fine Particles (PM 2.5) correlation in Iran with elevation, latitude and longitude results that the maximum correlation belongs to height, followed by latitude and longitude; meanwhile height and latitude are strongly and reversely correlate...
designing effective strategies for sediment management and control is closely related to identification of sediment sources in a drainage basin. one of the methods for investigating sediment sources is using magnetic tracers for erosion and sediment yield studies. sediment source identification using magnetic characteristics is a simple, inexpensive, quick and non-destructive method having appl...
Articles you may be interested in Distributed feedback terahertz frequency quantum cascade lasers with dual periodicity gratings Appl. Narrow-band injection seeding of a terahertz frequency quantum cascade laser: Selection and suppression of longitudinal modes Appl. High order sideband generation in terahertz quantum cascade lasers Appl. High frequency modulation of mid-infrared quantum cascade...
Background and aims Overexposure to industrial noise pollution induce hearing loss workers. Occupational hearing loss may cause interference whit oral communication, so it may increase the risk of occupational accidents in workplace as well as affects whit social activities. This study was conducted on Lavan Island, are of oil extracting regions in the south of Iran. The object of this s...
The development of high current, high brightness electron guns is critically important for free-electron laser and energy recovery linear-accelerator light source facilities. In this paper, we will review the technical requirements of such projects and the status of on-going research throughout the community including results of emittance measurements and high current beam performance.
Numerous industrial applications have begun to require higher power apparatus in recent years. Some medium voltage motor drives and utility applications require medium voltage and megawatt power level. For a medium voltage grid, it is troublesome to connect only one power semiconductor switch directly. As a result, a multilevel power converter structure has been introduced as an alternative in ...
Traditional high-frequency pulse width modulation (PWM) inverters for motor drives have several problems associated with their high frequency switching which produces high voltage change (dV/dt) rates. Multilevel inverters solve these problems because their devices switch at the fundamental frequency. Two different multilevel topologies are identified for use as a converter for electric drive...
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