PCFG parsing Research Papers - Academia.edu (original) (raw)

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- by
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- Computer Science, Artificial Intelligence, Natural Language Processing, Parsing
- by fateme asghari
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- Materials Science, Refractive Index, Optics and Photonics, Photonic crystal fiber

I. ABSTRACT The paper presents salient features of photonic crystal fiber (PCF) at one place. This paper focuses on the investigation of propagation characteristics of index guiding photonic crystal fibers from Scalar and Vectorial Effective index methods with an objective to compare and analyze the guided modes, spot size, spectral response of bend loss and spectral response of splice losses for various designs of PCF. Dispersion results so obtained from the above two methods is compared with the corresponding values of experimental result which points the range of validity and applicability of scalar and fully vectorial effective index methods for PCF. It is shown that the refractive index of fundamental space filling mode of PCF obtained by the above two methods matches well with that of finite element method (FEM) for the same design of PCF.

- by ANSHU DHIRENDRA VARSHNEY
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- Mathematics, Optics, Refractive Index, Photonic crystal fiber
- by Ha Thanh Le
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- Computer Science, Artificial Intelligence, Natural Language Processing, Parsing
- by Karthik Shankar
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- Materials Science, PCFG parsing

- by Dr. Anshu Varshney
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- Mathematics

A traditional concern of grammarians has been the question of whether the members of given pairs of expressions belong to the same or different syntactic categories. Consider the following example sentences. ( a ) I think Fido destroyed the kennel . ( b ) The kennel, I think Fido destroyed . Are the two underlined expressions members of the same syntactic category or not? The generative grammarians of the last quarter century have, almost without exception, taken the answer to be affirmative. In the present paper I explore the implications of taking the answer to be negative. The changes consequent upon this negative answer turn out to be very far-reaching: (i) it becomes as simple to state rules for constructions of the general type exemplified in ( b ) as it is for the canonical NP VP construction in ( a ); (ii) we immediately derive an explanation for a range of coordination facts that have remained quite mysterious since they were discovered by J. R. Ross some 15 years ago; (iii...

We have presented a detailed analysis of splice losses when an index-guiding photonic crystal fiber (PCF) is spliced to an identical PCF or to a step index single mode fiber (SMF). The calculations were based on the effective index model and on the Gaussian beam propagation theory. The wavelength dependence of the cladding index of the PCF has been taken properly into account. The effective spot size for different configurations of PCFs is obtained, which is used for computing the splice losses. The Gaussian approximation for the fundamental modal field leads to simple closed-form expressions for the splice losses produced by transverse, longitudinal and angular offsets.

- by George Kliros
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Photonic crystal fibers (PCFs) have been under intensive study for the past several years as they offer a number of unique and useful properties not achievable in conventional silica glass fibers. Important issues regarding the practical development of these PCFs are their splice and bending loss properties. In this work, we present an analytical evaluation of the splice losses as well as bending losses for PCFs using simple empirical relations in order to determine the Petermann-I and Petermann-II spot sizes as a function of the fundamental geometrical parameters - the air-hole diameter and the hole-pitch of the PCF. We consider the splice loss due to lateral, longitudinal as well as angular offsets, when a PCF is spliced to an identical PCF or to a step index single mode fiber (SMF). To deduce macro-bending loss in PCFs, we apply the standard radiation model for bend conventional fibers, making a full transformation of conventional SIF parameters to PCF effective parameters. The s...

- by George Kliros
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- Photonic Crystals, Splicing, Bending
- by Graham Town
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- Approximation Theory, Optical physics, Optical fiber, Indexation

This paper shows the calculated loss due to lateral misalignment in single mode fibers (SMFs) with basic wave functions. Experiment setup for measuring loss due to lateral misalignment is presented and used for loss measurement. Measured values and the results obtained by formulas are compared in order to confirm validity of the established experiment setup.

- by Matthias Haupt
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Analysis of losses at splice joints of dissimilar single-mode fibers (SMF), with three types of photonic crystal fibers (PCFs) are presented, using full-vectorial effective index methods and scalar effective index method. The effects of air-hole diameter (d) , air-hole spacing (Λ) , the air-filling factor d / Λ , dopant concentration in the core of PCFs on power coupling ratio and coupling losses at splice joints are analytically investigated. The results of the analysis may be used by network designers to predict over all splice joints losses when employing PCF-based devices in the optical networks.

- by Faramarz E. Seraji and +1
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To imprint a long-period grating (LPG) in a photonic crystal fiber (PCF) with an optimum response, first the parameters of the PCF should be optimized. In this paper, by using a semi-analytical enhanced improved vectorial effective index method, the optimized PCF parameters are determined by dividing the single-mode operation of the PCF into two regions in terms of air-hole spacing Λ (Λ>3 μm and Λ≤3 μm). For each region appropriate expressions are suggested to evaluate the PCF parameters. By calculating the effective refractive index difference between the optimized core and cladding of the PCF under a phase-matching condition, the optimum grating period in terms of the PCF parameters is obtained.

We report the waveguiding properties of photonic crystal fibers by adapting the effective index method. It has been shown that the waveguiding characteristics can be engineered for different configurations of PCFs. It is shown that the zero dispersion point can be shifted below 1.27 micron. Nearly zero dispersion-flattened behavior is observed for a specific combination of cladding parameters of Photonic crystal fiber.

- by Shailendra Varshney
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- Optical Communications, Dispersion, Photonic Crystal, Wave propagation
- by Mojtaba Mansour Abadi
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- by Faramarz E. Seraji
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- Photonics

"
An analysis of Fresnel loss at splice joint of single-mode fiber (SMF) and two types of photonic crystal fibers (PCFs) using improved full-vectorial effective index methods is presented. The effects of air-hole size , air-hole spacing , longitudinal misalignment between spliced SMFs and PCFs on the Fresnel loss is analyzed and is shown that when and the dopant concentration in the core of PCFs increases or the ratio decreases, the Fresnel loss will decrease. The results of the analysis may be used by network designers to predict over all loss when employing PCF-based devices in optical fiber networks. ()d()ΛΛ /dΛ
"

- by samira farsinezhad and +1
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An analysis of splice loss between photonic crystal fibers (PCFs) and conventional single-mode fibers (SMFs) is presented at bending and straight conditions, by using scalar effective index method (SEIM), vectorial effective index method (VEIM), and finite-difference frequency domain (FDFD) methods. It is
shown that when there is a slight bending at the vicinity of splice joint, the spot size increases sharply at higher frequencies. On the basis of the obtained results, a mechanism to optimize the splice loss between PCFs and conventional SMFs, both with any geometry, is suggested. The results can be utilized for PCF-
based devices to be jointed to SMF as a transmission medium.

- by Faramarz E. Seraji
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- PCFG parsing
- by Faramarz E. Seraji
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- Photonic Crystal Fibers

As an extension of decades of syntactic theorizing, treebanks have inherited a small set of phrasal categories, which abstract over the environments that the categories can occur in. Extending ideas from Johnson (1998), we explore encoding information from the local tree context in each category. We then discuss two clustering techniques which preserve the distributionally relevant category distinction, forming linguistically relevant generalizations and improving PCFG parsing performance.

- by John Pate
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- PCFG parsing, Constituency Parsing