Search results for "Cosine"
showing 10 items of 88 documents
Morphometry of Middle Bronze Age palstaves by discrete cosine transform.
2009
9 pages; International audience; The Discrete Cosine Transform (DCT) is a Fourier-related transform widely used in signal processing and well suited to the analysis of open outlines. This method was applied here to evaluate the discrimination power of the inner lateral rib for two palstave populations dating from the Middle Bronze Age, excavated in northwest France. A corpus of almost 400 palstaves (bronze axes) of the Breton and Norman types was processed, and compared to specimens found at Sermizelles in Burgundy. The procedure is robust and produces a discrimination in good agreement with the traditional typology. Besides the definition of a ‘standard' shape for each population, the morp…
Multipactor RF Breakdown in Coaxial Transmission Lines With Digitally Modulated Signals
2016
The aim of this paper is the study of the RF multipactor breakdown in coaxial transmission lines excited by a single carrier with a digitally modulated signal. Employing an in-house developed code, numerical simulations are performed to determine the RF multipactor voltage threshold for several digitally modulated signals under different modulations schemes: quadrature phase-shift keying, 16-quadrature amplitude modulation, 16-amplitude and phase-shift keying, and 32-amplitude and phase-shift keying. Moreover, a coarse method based on the envelope integration to determine the RF multipactor voltage threshold when involving arbitrary digital modulations is also presented. These results are a…
Flat-top ultra-wideband photonic filters based on mutual coherence function synthesis
2008
A novel all-incoherent optical circuit that allows for band-pass microwave-photonic filter design is presented and verified through numerical simulation. In contrast to conventional spectrum-sliced optical architectures that operate on the basis of a finite number of discrete taps, our proposal is based on arbitrary shaping of the spectrum of the broadband optical source in a conventional frequency encoder. This fact dramatically increases the free spectral range of the filter with respect to the conventional discrete-time optical processing. The filter transfer function is given by the mutual coherence function of the filtered source which allows, through an inverse problem, sculpting the …
4,5-Disubstituted 1-Methylimidazoles via Cyclization of Defined α-Aminoketones: Synthesis of Fungerin and Analogues I
2016
A protocol for the chemoselective synthesis of the fungal metabolite fungerin has been developed. First the required N-methyl α-aminoketone was generated starting from sarcosine, propiolic acid, and prenyl bromide. Marckwald thioimidazole cyclization and subsequent sulfur removal delivered the target fungerin as well as an analogue, respectively, displaying defined substitution patterns.
Anisotropic muon Knight shift in the HCP single crystals of Cd, Zn and Be
1984
In single crystal samples of Zn, Cd and Be (hcp structure) stroboscopicμSR measurements successfully revealed anisotropies in the muon Knight shift (Kμ). An anisotropic Kμ can provide information on the amount of non s-electrons screening the charge of the muon implanted in these metals as a light hydrogen isotope. In Cd, the anisotropic part depends strongly on the temperature and shows a change in sign at roughly 110 K. In Zn, the anisotropic part below 10 K turns out to comprise 4th order contributions in the direction cosines of the external field. This can be understood on the basis of an anisotropicg-factor of the conduction electrons or spin-orbit coupling, respectively.
Implicit analytic solutions for a nonlinear fractional partial differential beam equation
2020
Abstract Analytic solutions in implicit form are derived for a nonlinear partial differential equation (PDE) with fractional derivative elements, which can model the dynamics of a deterministically excited Euler-Bernoulli beam resting on a viscoelastic foundation. Specifically, the initial-boundary value problem for the corresponding PDE is reduced to an initial value problem for a nonlinear ordinary differential equation in a Hilbert space. Next, by employing the cosine and sine families of operators, a variation of parameters representation of the solution map is introduced. Due to the presence of a nonlinear term, a local fixed point theorem is employed to prove the local existence and u…
Impact of compatible solutes on the mechanical properties of fibronectin: a single molecule analysis
2003
The influence of ectoine and sarcosine on the mechanical properties of surface bound fibronectin has been investigated by means of force microscopy. Single molecule stretching experiments of fibronectin molecules reveal that ectoine and sarcosine increase the tendency of the polypeptide to coil, thus decreasing its apparent persistence length. This behavior can be explained by means of the preferential exclusion model implying that the osmolytes are expelled from the protein surface due to the increase in chemical potential of the denatured, i.e. stretched, state forcing the protein into a more compact structure. Detailed analysis of the unfolding forces, which are extracted from the succes…
Radiating and nonradiating behavior of hyperbolic-secant, raised-cosine, and Gaussian input light pulses in dispersion-managed fiber systems.
2005
We address the problem of optical light pulses, called dressed pulses, which do not match the stationary pulse profile of a dispersion-managed (DM) fiber system and we theoretically analyze the associated radiation. Comparing hyperbolic-secant, raised-cosine, and Gaussian pulse envelopes, we show that the general radiation figure is highly sensitive to the input pulse profile. As common general features for these pulse profiles, we find a rich variety of dynamical states that includes weak-, moderate-, and strong-radiation states, depending on the map strength of the DM fiber system. We demonstrate the existence of two intervals of map strengths where the emitted radiation is of considerabl…
Polypept(o)ides: Hybrid Systems Based on Polypeptides and Polypeptoids.
2015
Polypept(o)ides combine the multifunctionality and intrinsic stimuli-responsiveness of synthetic polypeptides with the "stealth"-like properties of the polypeptoid polysarcosine (poly(N-methyl glycine)). This class of block copolymers can be synthesized by sequential ring opening polymerization of α-amino acid N-carboxy-anhydrides (NCAs) and correspondingly of the N-substituted glycine N-carboxyanhydride (NNCA). The resulting block copolymers are characterized by Poisson-like molecular weight distributions, full end group integrity, and dispersities below 1.2. While polysarcosine may be able to tackle the currently arising issues regarding the gold standard PEG, including storage diseases i…
Synthesis and Sequential Deprotection of Triblock Copolypept(o)ides Using Orthogonal Protective Group Chemistry
2014
The synthesis of triblock copolymers based on polysarcosine, poly-N-ε-t-butyloxycarbonyl-l-lysine, and poly-N-ε-t-trifluoroacetyl-l-lysine by ring-opening polymerization of the corresponding α-amino acid N-carboxyanhydrides (NCAs) is described. For the synthesis of N-ε-t-butyloxycarbonyl-l-lysine (lysine(Boc)) NCAs, an acid-free method using trimethylsilylchloride/triethylamine as hydrochloric acid (HCl) scavengers is presented. This approach enables the synthesis of lysine(Boc) NCA of high purity (melting point 138.3 °C) in high yields. For triblock copolypept(o)ides, the degree of polymerization (Xn ) of the polysarcosine block is varied between 200 and 600; poly-N-ε-t-butyloxycarbonyl-l-…