Search results for "Curve"

Multivariate optimization of the hollow fibre liquid phase microextraction of muscimol in human urine samples.

2016

Abstract A liquid phase microextraction based on hollow fibre followed by liquid chromatographic determination was developed for the extraction and quantitation of the hallucinogenic muscimol from urine samples. Method applicability on polar hallucinogens was also tested on two alkaloids, a psychedelic hallucinogen, tryptamine and a polar amino acid, tryptophan which exists in its charged state in the entire pH range. A multivariate design of experiments was used in which a half fractional factorial approach was applied to screen six factors (donor phase pH, acceptor phase HCl concentration, carrier composition, stirring rate, extraction time and salt content) for their extent of vitality i…

Simulazioni Numeriche del Campo di Moto e della Caduta di Pressione in Tubi Elicoidali

2009

On Holditch's theorem and related kinematics

2019

El teorema de Holditch es un resultado clásico sobre áreas de curvas planas generadas por el movimiento de segmentos. Esta construcción está estrechamente relacionada con otros tipos de curvas como, por ejemplo, curvas paralelas, curvas de anchura constante o curvas de bicicletas. Se compilan las propiedades básicas de este tipo de curvas y se da una revisión histórica sobre el teorema de Holditch y teoremas relacionados de cinemática. Primero, la situación plana de Holditch se define rigurosamente y se consideran ciertos problemas como la existencia de dicha construcción o el modo de evitar movimientos retrógrados en el segmento que se va moviendo. En el enunciado del teorema de Holditch a…

A DGS gesture dictionary for modelling on mobile devices

2017

ABSTRACTInteractive or Dynamic Geometry System (DGS) is a tool that help to teach and learn geometry using a computer-based interactive environment. Traditionally, the interaction with DGS is based on keyboard and mouse events where the functionalities are accessed using a menu of icons. Nevertheless, recent findings suggest that such a traditional model of interaction has a steep learning curve and is inadequate to develop DGS for devices with multi-touch screens. Thus, we propose a new interaction model for DGS based on a gesture dictionary which enables the construction and manipulation of geometric objects without the need of accessing a menu of icons. The dictionary is divided into thr…

Quasi-periodic dipping in the ultraluminous X-ray source, NGC 247 ULX-1

2021

Most ultraluminous X-ray sources (ULXs) are believed to be stellar mass black holes or neutron stars accreting beyond the Eddington limit. Determining the nature of the compact object and the accretion mode from broadband spectroscopy is currently a challenge, but the observed timing properties provide insight into the compact object and details of the geometry and accretion processes. Here we report a timing analysis for an 800 ks XMM-Newton campaign on the supersoft ultraluminous X-ray source, NGC 247 ULX-1. Deep and frequent dips occur in the X-ray light curve, with the amplitude increasing with increasing energy band. Power spectra and coherence analysis reveals the dipping preferential…

Some Moduli and Constants Related to Metric Fixed Point Theory

2001

Indeed, there are a lot of quantitative descriptions of geometrical properties of Banach spaces. The most common way for creating these descriptions, is to define a real function (a “modulus” depending on the Banach space under consideration, and from this define a suitable constant or coefficient closely related to this function. The moduli and/or the constants are attempts to get a better understanding about two things: The shape of the unit ball of a space, and The hidden relations between weak and strong convergence of sequences.

Deformation of Polypropylene Foam Neopolen® P in Compression

2004

Neopolen® P is a two-phase cellular composite foam material produced by BASF AG, Germany. In most of the practical applications, Neopolen® P works under a range of small and compressive deformations. Therefore it is necessary to determine the moduli in compression and compressive strength in the most effective way for a wide range of foam densities: 22≤ρ84≤kg/m3. Several experimental methods of different precision for deformation properties of Neopolen® P were compared. The direct measurements performed by a universal testing machine were used for the main part of the experiments. They were compared with results obtained by a more precise and time-consuming method, using an inductive exten…

Complex Rating Curves for Sharp Crested Orifices and Rectangular or Triangular Weirs under Unsteady Flow Conditions

2021

The importance of discharge measurements is fully acknowledged in many research fields, mostly in hydrology. Numerous measurement devices and various overflow structures have been proposed for discharge measurements; however, their use is based on calibrated simple stage discharge relationships that may cause significant errors when unsteady flow conditions occur. This issue is quite common because of rainfall and runoff temporal variability that inhibits the achievement of the steady state. Although this issue has already been experimentally investigated, it seems that a physically based line of approach has not been attempted before. In this paper, unsteady stage discharge relationships o…

Study with surface electromyography, borg scale and rom upper trapezius, deltoid of the three portions (clavicular, acromial, spinal) and the latissi…

2017

The pathologies located at shoulder can be caused by misuse or continued implementation of a sporting practice or physical activity. These pathologies are second position in the ranking of Traumatologics and Orthopedic Clinicals (Windt, Koes, De Jong & Bouter, 1995). Shoulder’s muscle injuries can occur when the arm is in a position that exceeds normal, this fact is repeated in sport, may be the repetition of the hand signal of the inductor problem (Kapandji, 2006). Given the importance of muscle function of the shoulder joint, along the existing boom of new techniques in the specific muscle activation has been carried out an experimental study using a " Test neuro proprioceptive response "…

Spin Switching in Molecular Quantum Cellular Automata Based on Mixed-Valence Tetrameric Units

2016

In this article we focus on the study of spin effects in a single square-planar mixed-valence cell comprising two electrons and in coupled molecular cells for quantum cellular automata. Using the vibronic model we demonstrate that the polarizabilities of the cell are different in spin-singlet and spin-triplet states of the electronic pair. Based on this inference the concept of spin switching in molecular quantum cellular automata is proposed, and the conditions under which this effect is feasible are derived. In order to reveal these conditions we have performed a series of quantum-mechanical calculations of the vibronic energy levels of the isolated cell and of the cell subjected to the e…