Search results for " mechanics"
showing 10 items of 5066 documents
Profesors Dr. ing. h. c. Mārtiņš Bīmanis : dzīve un darbs
2014
Profesors M. Bīmanis bija LU rektors (1931-1933), Inženierzinātņu fakultātes dekāns (1927–1928,1930–1931, 1933–1934), LU prorektors saimniecības lietās (1923–1925). Grāmatā par profesoru M. Bīmani ir iekļauts viņa dzīves un darba apskats, atsevišķi profesora darbi un publikāciju bibliogrāfiskais rādītājs. Grāmatā ievietots tehnisko zinātņu vēstures pētnieka, Latvijas Zinātņu akadēmijas goda doktora Jāņa Klētnieka un medicīnas doktora profesora Māra Baltiņa papildinātais apskats ar profesora dzīves gājumu, akadēmisko un inženiertehnisko darbību. Nozīmīga ir M. Bīmaņa starptautiskā darbība, kurai uzmanību pievērsis RTU profesors Andris Krēsliņš rakstā „Mārtiņa Bīmaņa dibinātā Pasaules Enerģij…
Section: Advanced Composites and Applications (15th February, 2022, Riga, Latvia) : Book of Abstracts
2022
The section ‘Advanced Composites and Applications’ was organized by the Institute for Mechanics of Materials of the University of Latvia (LU MMI) on 15.02.2022 as a part of the annual 80th scientific conference of the University of Latvia. It was organized remotely in Zoom. The official language of the section was English. The duration of the presentation was 10-15 minutes. The section was devoted to the discussion of the recent results within following topics: structure and properties of polymers and polymer-based composites, long-term properties, creep, and environmental ageing, composites for advanced applications, mechanical aspects of technology, multifunctional properties.
Deformative Properties of Monotropic Plastic Foams with a Pronounced Strut-Like Strukture
1996
Disertācija angļu valodā, kopsavilkums arī latviešu un vācu valodā.
Casimir-Lifshitz force out of thermal equilibrium between dielectric gratings
2014
We calculate the Casimir-Lifshitz pressure in a system consisting of two different 1D dielectric lamellar gratings having two different temperatures and immersed in an environment having a third temperature. The calculation of the pressure is based on the knowledge of the scattering operators, deduced using the Fourier Modal Method. The behavior of the pressure is characterized in detail as a function of the three temperatures of the system as well as the geometrical parameters of the two gratings. We show that the interplay between non-equilibrium effects and geometrical periodicity offers a rich scenario for the manipulation of the force. In particular, we find regimes where the force can…
On the carrier of inertia
2018
A change in momentum will inevitably perturb the all-embracing vacuum, whose reaction we understand as inertia. Since the vacuum's physical properties relate to light, we propose that the vacuum embodies photons, but in pairs without net electromagnetic fields. In this physical form the free space houses energy in balance with the energy of matter in the whole Universe. Likewise, we reason that a local gravitational potential is the vacuum in a local balance with energy that is bound to a body. Since a body couples to the same vacuum universally and locally, we understand that inertial and gravitational masses are identical. By the same token, we infer that gravity and electromagnetism shar…
Mechanical ventilation parameters in critically ill COVID-19 patients: a scoping review
2021
Abstract Background The mortality of critically ill patients with COVID-19 is high, particularly among those receiving mechanical ventilation (MV). Despite the high number of patients treated worldwide, data on respiratory mechanics are currently scarce and the optimal setting of MV remains to be defined. This scoping review aims to provide an overview of available data about respiratory mechanics, gas exchange and MV settings in patients admitted to intensive care units (ICUs) for COVID-19-associated acute respiratory failure, and to identify knowledge gaps. Main text PubMed, EMBASE, and MEDLINE databases were searched from inception to October 30, 2020 for studies providing at least one v…
Revisiting the Nonadiabatic Process in 1,2-Dioxetane.
2015
Determining the ground and excited-state decomposition mechanisms of 1,2-dioxetane is essential to understand the chemiluminescence and bioluminescence phenomena. Several experimental and theoretical studies has been performed in the past without reaching a converged description. The reason is in part associated with the complex nonadiabatic process taking place along the reaction. The present study is an extension of a previous work (De Vico, L.; Liu, Y.-J.; Krogh, J. W.; Lindh, R. J. Phys. Chem. A 2007, 111, 8013-8019) in which a two-step mechanism was established for the chemiluminescence involving asynchronous O-O' and C-C' bond dissociations. New high-level multistate multi configurati…
Abelian integrals and limit cycles
2006
Abstract The paper deals with generic perturbations from a Hamiltonian planar vector field and more precisely with the number and bifurcation pattern of the limit cycles. In this paper we show that near a 2-saddle cycle, the number of limit cycles produced in unfoldings with one unbroken connection, can exceed the number of zeros of the related Abelian integral, even if the latter represents a stable elementary catastrophe. We however also show that in general, finite codimension of the Abelian integral leads to a finite upper bound on the local cyclicity. In the treatment, we introduce the notion of simple asymptotic scale deformation.
Alien limit cycles near a Hamiltonian 2-saddle cycle
2005
Abstract It is known that perturbations from a Hamiltonian 2-saddle cycle Γ can produce limit cycles that are not covered by the Abelian integral, even when it is generic. These limit cycles are called alien limit cycles. This phenomenon cannot appear in the case that Γ is a periodic orbit, a non-degenerate singularity, or a saddle loop. In this Note, we present a way to study this phenomenon in a particular unfolding of a Hamiltonian 2-saddle cycle, keeping one connection unbroken at the bifurcation. To cite this article: M. Caubergh et al., C. R. Acad. Sci. Paris, Ser. I 340 (2005).
ON THE CALCULATION OF THE HEAT CAPACITY IN PATH INTEGRAL MONTE CARLO SIMULATIONS
1992
In Path Integral Monte Carlo simulations the systems partition function is mapped to an equivalent classical one at the expense of a temperature-dependent Hamiltonian with an additional imaginary time dimension. As a consequence the standard relation linking the heat capacity Cv to the energy fluctuations, <E2>−<E>2, which is useful in standard classical problems with temperature-independent Hamiltonian, becomes invalid. Instead, it gets replaced by the general relation [Formula: see text] for the intensive heat capacity estimator; β being the inverse temperature and the subscript P indicates the P-fold discretization in the imaginary time direction. This heatcapacity estimator…