نتایج جستجو برای: dfb

تعداد نتایج: 805  

Journal: :Forests 2022

Changes in climate are altering disturbance regimes forests of western North America, leading to increases the potential for events overlap time and space. Though interactions between abiotic biotic (e.g., effect bark beetle outbreak on subsequent wildfire) have been widely studied, multiple disturbances poorly understood. Defoliating insects, such as spruce budworm (WSB; Choristoneura freemann...

2006
Hsiang-Chen Chui Ming-Sheng Ko Yi-Wei Liu Tyson Lin Jow-Tsong Shy Sen-Yen Shaw Rostislav V. Roussev Martin M. Fejer

A 197.2THz (1520.2nm) ITU-T grid distributed feedback (DFB) diode laser is frequency stabilized at 197.198THz by 1ocking its second harmonic (SH) signal on the rubidium 5S1/27S1/2 two-photon transition at 394.396THz (760.1 nm). With 100mW from the DFB diode laser and amplifying by an erbium-doped fiber amplifier, we obtain an SH power of 15mW using a periodically poled lithium niobate (PPLN) wa...

2005
H. Su L. Zhang A. L. Gray R. Wang P. M. Varangis L. F. Lester

We measure, for the first time, the gain compression coefficient and above-threshold linewidth enhancement factor (alpha parameter) in quantum dot (QD) distributed feedback lasers (DFB) by time-resolved-chirp (TRC) characterization. The alpha parameter is measured to be 2.6 at threshold and increases to 8 when the output power of the QD DFB is increased to 3 mW. The dependence of the above-thre...

Journal: :Applied optics 2010
Eva M Calzado Jose M Villalvilla Pedro G Boj Jose A Quintana Pablo A Postigo María A Díaz-García

Single-mode second-order distributed feedback (DFB) lasers with low threshold, based on polystyrene films doped with 30 wt. % of the hole-transporting organic molecule N,N'-bis (3-methylphenyl)-N,N'-diphenylbenzidine (TPD) are reported. The laser emission wavelength was tuned between 415 and 427 nm by film thickness variation. The effectiveness of the DFB grating in improving the laser performa...

2002
Atif Bin Mansoor Awais Mansoor

This paper describes a novel approach to finger print matching using a new mathematical transform: the contourlet transform. Contourlet improves traditional wavelet based approaches by incorporating a directional component. It finds a direct discrete-space construction and is therefore computationally efficient. In this paper, 2-D spectrum is divided into fine slices using iterated directional ...

Journal: :The Review of Laser Engineering 1987

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه الزهراء - دانشکده علوم پایه 1394

لیزرهای dfb-rf نویدبخش دستیابی به چشمه های لیزری تک فرکانس با پهنای خط باریک و با خاصیت کوک پذیری طول موج از مادون قرمز دور تا طول موج دیدنی هستند. هدف اصلی این رساله تحلیل و ارزیابی عملکرد لیزرهای فیبر رامان با فیدبک توزیع شده (dfb- rf) با در نظر گرفتن اثرات نوری غیرخطی است. ساختار مورد بررسی در این پایان نامه یک ساختار با انتقال فاز ?/2 که در وسط توری فرض شده است می باشد. مدلسازی نظری لیزر بر...

2001
Tami R. Randolph Mark J. T. Smith

In this paper, we explore a novel approach to enhancing ngerprint images using a new binary directional lter bank (DFB). Automated ngerprint identi cation systems (AFIS) are used to classify a ngerprint in a large volume of images. Many approaches to AFIS have been suggested, most sharing in common the idea of extracting discriminate feature representations. As part of that process, the raw nge...

Journal: :EURASIP J. Adv. Sig. Proc. 2008
Truong T. Nguyen Yilong Liu Hervé Chauris Soontorn Oraintara

This paper analyzed the implementational aspects of the contourlet filter bank (or the pyramidal directional filter bank (PDFB)), and considered its application in image coding. First, details of the binary tree-structured directional filter bank (DFB) are presented, including a modification to minimize the phase delay factor and necessary steps for handling rectangular images. The PDFB is view...

Journal: :Drug metabolism and disposition: the biological fate of chemicals 2004
Deborah A Nicoll-Griffith Nathalie Chauret Robert Houle Stephen H Day Michelle D'Antoni José M Silva

The benzyloxy-substituted lactone cyclooxygenase-2 inhibitor DFB [3-[(3,4-difluorobenzyl)oxy]-5,5-dimethyl-4-[4-(methylsulfonyl)phenyl]furan-2(5H)-one] is metabolized in human and rat liver microsomal incubations and hepatocytes to a fluorescent metabolite, DFH [3-hydroxy-5,5-dimethyl-4-[4-(methylsulfonyl)phenyl]furan-2(5H)-one]. This process is CYP3A-mediated in both species, as demonstrated b...

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