نتایج جستجو برای: سیگنالهای uhf

تعداد نتایج: 2607  

ژورنال: :مجله صوت و ارتعاش 2014
وحید حقیقی صدیقه ملک محمدی سید مهدی موسوی

یکی از روش های تولید امواج فراصوتی جهت کاربرد در آزمون های فراصوتی، فرود یک تپ لیزری کوتاه بر سطح نمونه است. شناسایی و ارزیابی سیگنالهای امواج تولید شده یکی از دغدغه های موجود در این زمینه است.در اثر این فرآیند موج فراصوتی در دو رژیم گوناگون ترموالاستیک (گسترش گرمایی) و فرسایش تولید می شود.در این مقاله ابتدا به شبیه سازی سیگنالهای موج فراصوتی در هر دو رژیم پرداخته و سپس سیگنالهای تولید شده در آ...

2013
Miaofen Zhu Guojin Chen Ming Xu Tingting Liu Dong Xie Yanping Zhang

The detection and fault identification of the partial discharge is the important aspect for the monitoring of the power equipment. For the lacks of the traditional detection methods, this paper analyzed the UHF signal characteristic parameters of the power equipment’s partial discharge, and developed the UHF detection system of the partial discharge. The A/D technology of the gain equalization ...

2007
Vojtech Derbek Christian Steger Reinhold Weiss Josef Preishuber-Pfluegl Markus Pistauer

Nowadays, UHF RFID performance gains on increased importance as tags, readers, protocols and applications are addressed no longer as separated devices, but rather as a system. Resources of transponders are limited in size and available power, which is retrieved from the electric field generated by interrogator’s antenna. This power is restricted by national regulations. As UHF RFID systems have...

2014
Jing Yang Chao Pan Caijun Wang Dapeng Jiang Biyang Wen

Coastal UHF radar provides a unique capability to measure the sea surface dynamic parameters and detect small moving targets, by exploiting the low energy loss of electromagnetic waves propagating along the salty and good conducting ocean surface. It could compensate the blind zone of HF surface wave radar at close range and reach further distance than microwave radars. However, its performance...

2003
HIROYUKI OSAKA

Let 1 ∈ A ⊂ B be an inclusion of C*-algebras of C*-index-finite type with depth 2. We try to compute topological stable rank of B (= tsr(B)) when A has topological stable rank one. We show that tsr(B) ≤ 2 when A is a tsr boundedly divisible algebra, in particular, A is a C*-minimal tensor product UHF ⊗ D with tsr(D) = 1. When G is a finite group and α is an action of G on UHF, we know that a cr...

1998
P. N. Collis M. T. Rietveld

Mesospheric observations were obtained by the EISCAT UHF and VHF radars during the solar proton event of March 1990. We present the ®rst comparison of incoherent-scatter spectral measurements from the middle mesosphere using simultaneous, colocated observations by the two radars. VHF spectra observed with a vertical antenna were found to be signi®cantly narrower than model predictions, in agree...

2017
Marwa Zamali Lotfi Osman Hedi Ragad Mohamed Latrach

An Ultra High Frequency (UHF) half-loop antenna used in Radio Frequency Identification (RFID) systems is proposed with a planar patterned metamaterial structure of compact size. The size of the planar patterned metamaterial structure is (0.20λ*0.20λ*0.0023λ) mm. This antenna consists of two metamaterial unit cells having negative permittivity and permeability. Simulation results of input return...

2010
T. MURAKAMI

ITH the advent of ultra-high-frequency television and the subsequent allocation of specific UHF channels, the need for a VHF-UHF television tuner becomes apparent. This tuner should ideally make the maximum use of the same components on VHF and UHF, so that there would be a minimum duplication of parts. This design should be one which would give optimum performance and still be easy to fabricat...

Journal: :The Journal of chemical physics 2011
Joshua W Hollett Peter M W Gill

Restricted Hartree-Fock (RHF) and UHF wavefunctions for beryllium-like ions with nuclear charge 3 ≤ Z ≤ 5 are found using a near-complete Slater basis set. The triplet (RHF → UHF) instability and correlation energy are investigated as a function of Z and we find that the instability vanishes for Z > 4.5. We reproduce this surprising behavior using a minimal-basis model and, by comparing with th...

2016
Tapas Chakravarty P. Balamuralidhar

This chapter addresses the various design issues, requirements, and specifications in designing reader antennas for UHF RFID applications. In a typical UHF system, the RFID reader antennas are geography specific; that is, there are different antennas for different geography, namely North America, Europe, et cetera. The discussion on the design challenges and performance expectations lead to a n...

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