نتایج جستجو برای: doppler measurement
تعداد نتایج: 482401 فیلتر نتایج به سال:
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موقعیت یابی، مهم ترین وظیفه یک سیستم ناوبری می باشد و عموماً بر اساس موقعیت بدست آمده و نیز بردار سرعت و زوایای سمت و تراز استخراج شده از ناوبری، سیگنال ها و فرامین سیستم هدایت و کنترل تعیین می شوند. در یک سیستم ناوبری اینرسی که محاسبات آن بر مبنای قانون دوم نیوتن است، عموماً از خروجی سنسورهای اینرسی، یعنی شتاب سنج ها و ژیروسکوپ ها، برای تعیین موقعیت و وضعیت استفاده می شود. در سال های اخیر به منظ...
OBJECTIVES This study evaluates whether a quantitative measurement of Doppler intensity during handgrip may disclose coronary vasomotor dysfunction in patients with coronary artery disease (CAD). BACKGROUND Atherosclerotic coronary segments show an exaggerated constrictive response to handgrip. The intensity of the scattered Doppler signal is proportional to the number of blood cells flowing ...
Glaucoma is one of the leading causes of blindness worldwide. Historically, it has been considered an ocular disease primary caused by pathological intraocular pressure (IOP). Recently, researchers have emphasized intracranial pressure (ICP), as translaminar counter pressure against IOP may play a role in glaucoma development and progression. It remains controversial what is the best way to mea...
Delay/Doppler radar altimetry has been receiving an increasing interest, especially since the launch of the first altimeter in 2010. It aims at reducing the measurement noise and increasing the along-track resolution in comparison with conventional pulse limited altimetry. A semi-analytical model was recently introduced for this new generation of delay/Doppler altimeters. The first contribution...
Wind speed is a most important weather parameter to record and monitor for many applications like meteorology, shipping, aviation etc. Wind observations are very important for general (operational) aviation meteorology, and weather prediction. Wind profilers are vertically directed pulsed Doppler radars which can analyze the back scattered signals and determine the velocity of air along the bea...
We carried out a car-to-infrastructure (C21) and car-to-car (C2C) 4X4 multiple-input multipleoutput (MIMO) radio channel measurement campaign at 5.2 GHz in Lund, Sweden. This paper presents first results on pathloss, power-delay profiles, and delay-Doppler spectra in a C2C highway scenario, where both cars were traveling in opposite directions. A pathloss coefficient of 1.8 yields the best fit ...
An ultrasound instrument has been developed that combines a real-time cross-sectional imaging system and a spectrum analyzer-based Doppler velocimeter. This combination allows the Doppler sample volume to be superimposed on the cross-sectional image of the heart so that the sample volume can be located accurately. The same 2.2 MHz transducer utilized for cross-sectional imaging is stopped mecha...
The aim of the present study was to test the validity of the transthoracic electrical bioimpedance method PhysioFlow® to measure stroke volume in patients with chronic anemia. Stroke volume index (SVI), as well as cardiac index (CI) obtained by transthoracic electrical bioimpedance method and doppler echocardiography were compared in healthy subjects (n = 25) and patients with chronic anemia (i...
BACKGROUND to determine the usefulness of Doppler ultrasound measurement of resistive index (RI) in differentiating obstructive from non-obstructive hydronephrosis in children. METHODS From August 2011 to November 2012, renal Doppler assessments of the intra-renal renal arteries were performed on 16 children (19 kidneys) with congenital hydronephrosis. the independent t-test was used to asses...
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