Search results for "Stability."

Mathematical models and stability analysis of induction motors under sudden changes of load

2013

A library of monoalkenylsilsesquioxanes as potential comonomers for synthesis of hybrid materials

2018

In this paper we demonstrate a facile and efficient synthesis of monoalkenylsubstituted POSS compounds, i.e., R7(Si8O12)-alkenyl and R7(Si8O12)(OSiMe2)-alkenyl with a functional alkenyl group of chain length (from vinyl to dec-9-enyl, with or without additional –OSiMe2– spacer between the silsesquioxane core and alkenyl moiety) and with five types of inert groups (Et, iBu, iOc, Cy, Ph) at the POSS core. These compounds constitute a library of monosubstituted POSS systems, including thorough spectroscopic and thermal characteristics. These findings could be especially useful for material chemists applying the compounds as modifiers or comonomers for copolymerization reaction, e.g., with olef…

Thermal and thermo-oxidative stability and kinetics of decomposition of PHBV/sisal composites

2017

The decomposition behaviours of composites made of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and sisal were assessed in terms of thermal stability and decomposition kinetics, under inert and oxidative conditions, by means of multi-rate linear non-isothermal thermogravimetric experiments. A statistical design of experiments was applied to study the influence of the addition of sisal (0-10-20-30%wt), the presence coupling agent (Yes/No) and the applied conditions of work (inert or oxidative). An improvement of the thermal and thermo-oxidative stability of PHBV with the addition of sisal was observed for all cases. An accurate methodology based on iso-conversional methods was applied…

Latvijas rūpniecībai aktuālu farmaceitiski aktīvo vielu kristālsolvāti

2013

ANOTĀCIJA Promocijas darbs veltīts Latvijas tautsaimniecībai aktuālu farmaceitiski aktīvo vielu (FAV) izpētei. Veikti apskatīto vielu kristālsolvātu meklējumi un iegūtas līdz šim neaprakstītas vielu kristāliskās formas. Novērtēta iegūto formu stabilitāte iegūšanas, ražošanas un uzglabāšanas apstākļos. Atsevišķām FAV veikta struktūras noteikšana, gan izmantojot pulvera rentgendifraktometriju, gan monokristālu rentgendifraktometriju. Iegūtie rezultāti ir aktuāli zāļu ražotājiem, kā arī tiem ir zinātniska nozīme no FAV īpašību apzināšanas un metožu attīstības viedokļa. Atslēgas vārdi: kristālsolvāti, vielas stāvokļa diagramma, nestehiometriskie solvāti, vielu termodinamiskā stabilitāte, fāžu p…

Alteration-Induced Volcano Instability at La Soufrière de Guadeloupe (Eastern Caribbean)

2021

International audience; Volcanoes are unstable structures that deform laterally and frequently experience mass wasting events. Hydrothermal alteration is often invoked as a mechanism that contributes significantly to volcano instability. We present a study that combines laboratory experiments, geophysical data, and large-scale numerical modeling to better understand the influence of alteration on volcano stability, using La Soufrière de Guadeloupe (Eastern Caribbean) as a case study. Laboratory experiments on variably altered (advanced argillic alteration) blocks show that uniaxial compressive strength, Young's modulus, and cohesion decrease as a function of increasing alteration, but that …

Variational principle and bifurcations in stability analysis of panels

2014

In this paper, the stability of a simply supported axially moving elastic panel is considered. A complex variable technique and bifurcation theory are applied. As a result, variational equations and a variational principle are derived. Anal- ysis of the variational principle allows the study of qualitative properties of the bifurcation points. Asymptotic behaviour in a small neighbourhood around an arbitrary bifurcation point is analyzed and presented. It is shown analytically that the eigenvalue curves in the (ω, V0) plane cross both the ω and V0 axes perpendicularly. It is also shown that near each bifur- cation point, the dependence ω(V0) for each mode approximately follows the shape of …

High-Reynolds-number turbulent cavity flow using the lattice Boltzmann method

2018

We present a boundary condition scheme for the lattice Boltzmann method that has significantly improved stability for modeling turbulent flows while maintaining excellent parallel scalability. Simulations of a three-dimensional lid-driven cavity flow are found to be stable up to the unprecedented Reynolds number $\mathrm{Re}=5\ifmmode\times\else\texttimes\fi{}{10}^{4}$ for this setup. Excellent agreement with energy balance equations, computational and experimental results are shown. We quantify rises in the production of turbulence and turbulent drag, and determine peak locations of turbulent production.

Experimental evolution of genome architecture and complexity in an RNA virus

2016

Introducción La evolución de la arquitectura del genoma – las dimensiones y la organización del material hereditario de un organismo – es poco conocida. Existe una variación asombrosa en la arquitectura genómica entre diferentes organismos. Los virus tienden a tener genomas pequeños, con un mínimo de secuencias intergénicas y típicamente con genes solapantes, los cuales se cree son una forma de compresión del genoma que permite al virus incrementar su número de proteínas sin aumentar su tamaño. Los procariotas tienen genomas compactos, pero con secuencias intergénicas más largas que los virus, y los genes con solapamientos largos son escasos. Los eucariotas presentan una amplia gama de tama…

Ultrasound-guided viscosupplementation in glenohumeral microinstability in sports athletes

2014

Anticipatory Postural Adjustments and kinematic arm features when postural stability is manipulated

2018

International audience; Beyond the classical paradigm that presents the Anticipatory Postural Adjustments (APAs) as a manner to create forces that counteract disturbances arising from the moving segment during a pointing task, there is a controversial discussion about the role APAs to facilitate the movement and perform a task accurately. In addition, arm kinematics features are classically used to infer the content of motor planning for the execution and the control of arm movements, The present study aimed to disentangle the conflicting role of APAs during an arm-pointing task in which the subjects reach a central diode that suddenly turns on, while their postural stability was manipulate…