Search results for " Geometry"
showing 10 items of 2294 documents
Four Quadrant Switch Based Multiple-Input DC-DC Converter
2021
In this paper, a novel non-isolated multiple input dc-dc converter (MIC) is proposed. The MIC uses four-quadrant switches, only one inductor and capacitor. It is capable of bidirectional operation in non-inverting buck-boost configuration and can accommodate the simultaneous transfer of energy from more than one source of different voltage levels to the DC bus. This MIC is analysed for two inputs in this paper. As compared to existing MICs in literature, the proposed converter utilizes less number of inductors and requires only one switch to integrate any extra energy storage. Different operation modes of the proposed MIC are numerically verified and validated on a high-fidelity hardware-in…
A real-time auto calibration technique for stereo camera
2020
Calibration of the internal and external parameters of a stereo vision camera is a well-known research problem in the computer vision. Usually, to get accurate 3D results the camera should be manua...
Robust auto calibration technique for stereo camera
2017
Calibration of the internal and external parameters of a stereo vision camera is a well-known research problem in the computer vision. Usually, to get accurate 3D results the camera should be manually calibrate accurately as well. This paper proposes a robust approach to Auto Calibration stereo camera Without intervention of the user. There are several methods and techniques of calibration that have been proven, in this work we exploiting the geometric constraint, namely, the epipolar geometry. We specifically focuses to use 7 techniques for Features Extraction (SURF, BRISK, FAST, FREAK, MinEigen, MSERF, SIFT), however tries to establish the correspondences between points extracted in stere…
Immediate 3-dimensional ridge augmentation after extraction of periodontally hopeless tooth using chinblock graft
2015
Background: The aim of the present study was to evaluate clinically and radiographically, the efficacy of immediate ridge augmentation to reconstruct the vertical and horizontal dimensions at extraction sites of periodontally hopeless tooth using an autogenous chin block graft. Material and Methods: A total of 11 patients (7 male & 4 female) with localized advanced bone loss around single rooted teeth having hopeless prognosis and indicated for extraction were selected for the study. The teeth were atraumatically extracted and deficient sites were augmented using autogenous chin block graft. Parameters like clinically soft tissue height - width and also radiographic ridge height -width were…
Courbe d'une fraction rationnelle et courbes de Bézier à points massiques
2019
Modelling polynomial curves or arcs with Bezier curves can be seen as a basis conversion not so easy for the rational curves. The classical representation of Rational curves based on controlled points with non negative weights as in NURBS does not cover all rational curves. This can be fixed by using the rational Bezier representation by mass points that are weighted points with negative or null weights. The curve of any rational function includes arcs denoted as connex components. These curves and their asymptotic lines are here modelled by the use of mass control points. The asymptotic lines are described by a point that are one weighted point or a vector. An algorithm proposes to represe…
Cleavage of Ge–Ge and Sn–Sn Triple Bonds in Heavy Group 14 Element Alkyne Analogues (EAriPr4)2 (E = Ge, Sn; AriPr4 = C6H3-2,6(C6H3-2,6-iPr2)2) by Rea…
2016
The reactions of heavier group 14 element alkyne analogues (EAriPr4)2 (E = Ge, Sn; AriPr4 = C6H3-2,6-(C6H3-2,6-iPr2)2) with the group 6 transition-metal carbonyls M(CO)6 (M = Cr, Mo, W) under UV irradiation resulted in the cleavage of the E–E triple bond and the formation of the complexes {AriPr4EM(CO)4}2 (1–6), which were characterized by single crystal X-ray diffraction as well as by IR and multinuclear NMR spectroscopy. Single-crystal X-ray structural analyses of 1–6 showed that the complexes have a nearly planar rhomboid M2E2 core with three-coordinate group 14 atoms. The coordination geometry at the group 6 metals is distorted octahedral formed by four carbonyl groups as well as two br…
Coordination Chemistry of Cu2+ Complexes of Small N-Alkylated Tetra-azacyclophanes with SOD Activity
2018
A new tetraaza-pyridinophane macrocycle (L1) N-alkylated with two isopropyl and one methyl groups symmetrically disposed has been prepared and its behavior compared with those of the unsubstituted pyridinophane (L3) and the related compound with three methyl groups (L2). The protonation studies show that, first, a proton binds to the central methylated amine group of L1, while, second protonation leads to a reorganization of the protons that are at this stage attached to the lateral isopropylated amines. The X-ray structure of [HL1]+ agrees with the UV–vis and NMR studies as well as with the results of DFT calculations. The stability of the Cu2+ complexes decreases on increasing the bulkine…
Polymerizable and polymeric zwitterionic surfactants: 1. Synthesis and bulk properties
1991
Abstract The synthesis of a series of permanently zwitterionic surfactant monomers based on sulphobetaines and the preparation of their polymers is described. Solubilities, thermal properties and bulk structures of the zwitterionic polymers are studied with respect to their molecular architecture, and compared with cationic analogues. The various solubilities of the polymers can be correlated with their molecular geometry, enabling differentiation into distinct classes. This behaviour is paralleled by the observed bulk structures of the polymers where distinct classes of superstructures are present. However, independently of the molecular geometry, no thermal transition could be detected fo…
Oxygen atom transfer catalysis by dioxidomolybdenum(VI) complexes of pyridyl aminophenolate ligands
2021
Abstract A series of new cationic dioxidomolybdenum(VI) complexes [MoO2(Ln)]PF6 (2–5) with the tripodal tetradentate pyridyl aminophenolate ligands HL2-HL5 have been synthesized and characterized. Ligands HL2-HL4 carry substituents in the 4-position of the phenolate ring, viz. Cl, Br and NO2, respectively, whereas the ligand HL5, N-(2-hydroxy-3,5-di-tert-butylbenzyl)-N,N-bis(2-pyridylmethyl)amine, is a derivative of 3,5-di-tert-butylsalicylaldehyde. X-ray crystal structures of complexes 2, 3 and 5 reveal that they have a distorted octahedral geometry with the bonding parameters around the metal centres being practically similar. Stoichiometric oxygen atom transfer (OAT) properties of 5 with…
Speciation of tin(II) in aqueous solution: thermodynamic and spectroscopic study of simple and mixed hydroxocarboxylate complexes
2013
This contribution reports the results of potentiometric and Mossbauer investigations on the formation, stability, and structure of binary and ternary mono- and binuclear complexes of Sn2+ with three hydroxocarboxylic ligands (namely L = tartrate, malate, and citrate) and chloride at T = 298.15 K in different ionic media and ionic strengths (0.15 and 1.00 mol dm−3 in NaCl(aq) and 1.00 mol dm−3 in NaNO3(aq)). The stability constants of various simple Sn i H j L (2+−) and mixed Sn i H j L k Cl (2+−−) species obtained in the different experimental conditions are reported, and various speciation diagrams of the simple and mixed systems are shown in different conditions. The sequestering ability …