310 research outputs found
Statistical analysis of self-similar behaviour in the shear induced melting model
The analysis of the system behavior under the effect of the additive noises
has been done using a simple model of shear melting. The situation with low
intensity of the order parameter noise has been investigated in detail, and
time dependence of the order parameter has been calculated. A distinctive
feature of the obtained dependence is power-law distribution and
self-similarity. The generalized Hurst exponent of the time series has been
found within multifractal detrended fluctuation analysis. It is shown that the
self-similarity of the time series increases when the noise intensity reduces.Comment: 11 pages, 9 figures, 29 reference
On the validity of the method of reduction of dimensionality: area of contact, average interfacial separation and contact stiffness
It has recently been suggested that many contact mechanics problems between
solids can be accurately studied by mapping the problem on an effective one
dimensional (1D) elastic foundation model. Using this 1D mapping we calculate
the contact area and the average interfacial separation between elastic solids
with nominally flat but randomly rough surfaces. We show, by comparison to
exact numerical results, that the 1D mapping method fails even qualitatively.
We also calculate the normal interfacial stiffness and compare it with the
result of an analytical study. We attribute the failure of the elastic
foundation model to the neglect of the long-range elastic coupling between the
asperity contact regions.Comment: 5 pages, 4 figures, 29 reference
36 Months Survivability And Its Predictors In Patients With Chronic Heart Failure And Decreased Fraction Of Left Ventricular Ejection Depending On Sex
Aim of the work: to compare survivability parameters during 36 months and their predictors among men and women with chronic heart failure and decreased fraction of left ventricular ejection.Materials and methods: the research included 356 patients with CHF (NYHA ІІ –ІV) with decreased LVEF<40 %, 18–75 years old. Using Kaplan-Meier method, there was analyzed the survivability in men and women during 36 months, then there were analyzed independent factors that influenced survivability terms depending on sex using the multiple logistic regression.Results. Our analysis of the survivability of patients with CHF with decreased LVEF demonstrated that the cumulative survival after 3 years of observation was 49 and 51 % for men and women, respectively. The curves of 36 months survivability didn\u27t reliably differ. At the analysis of factors, associated with the bad prognosis, there were observed differences between groups of men and women with CHF. Thus, in men the predictors of 36 month survival were: the thickness of the right ventricle wall, size of the right atrium, end-diastolic volume and end-systolic volume of LV, indices of EDV and ESV of LV, urinary acid level, value of LVEF. In women the predictors of survivability during 3 years were the following parameters: BMI, DM type 2 in an anamnesis, end-diastolic size of LV, end-systolic size of LV, blood glucose level, LVEF.Conclusion. The survivability of men and women with CHF with decreased LVEF during 36 months didn\u27t reliably differ and was 49 and 51 % respectively. But predictors of the lethal outcome in men and women essentially differed during 36 months, and their number is essentially higher in men
Stick-slip boundary friction mode as a second-order phase transition with an inhomogeneous distribution of elastic stress in the contact area
This article presents an investigation of the dynamical contact between two atomically flat surfaces separated by an ultrathin lubricant film. Using a thermodynamic approach we describe the second-order phase transition between two structural states of the lubricant which leads to the stick–slip mode of boundary friction. An analytical description and numerical simulation with radial distributions of the order parameter, stress and strain were performed to investigate the spatial inhomogeneity. It is shown that in the case when the driving device is connected to the upper part of the friction block through an elastic spring, the frequency of the melting/solidification phase transitions increases with time
DYNAMICAL MODEL OF THE ASYMMETRIC ACTUATOR OF DIRECTIONAL MOTION BASED ON POWER-LAW GRADED MATERIALS
We consider an actuator whose driving bodies are made of Power-Law graded materials. The directional motion is generated by an asymmetric mechanism producing simultaneously vertical and horizontal oscillations of the indenter. The dynamic contact of gradient materials is described and the equation of motion for the drive is written down and analyzed. It is shown that the exponent of the elastic inhomogeneity significantly affects the average velocity of motion of the cargo, which can be dragged by the drive
Paramagnetic Meissner effect in ZrB12 single crystal with non-monotonic vortex-vortex interactions
The magnetic response related to paramagnetic Meissner effect (PME) is
studied in a high quality single crystal ZrB12 with non-monotonic vortex-vortex
interactions. We observe the expulsion and penetration of magnetic flux in the
form of vortex clusters with increasing temperature. A vortex phase diagram is
constructed which shows that the PME can be explained by considering the
interplay among the flux compression, the different temperature dependencies of
the vortex-vortex and the vortex-pin interactions, and thermal fluctuations.
Such a scenario is in good agreement with the results of the magnetic
relaxation measurements.Comment: accepted by New Journal of Physic
ВЫБОР БЕРЕГОВЫХ ТЕРМИНАЛОВ ДЛЯ ХРАНЕНИЯ ЖИДКОГО ТОПЛИВА
The article provides an analysis of costs of liquid fuel storage at port and coastal terminals involved in freight transportation. Among other things, it gives estimation of selection of tanks’ rational volumes, payback period of buffer tanks construction, cost of storage for one ton of crude oil, fuel oil, diesel fuel per day, transportation of such goods in autumnwinter and spring-summer periods on certain routes. Moreover, on the basis of indicators of terminals of Russian coastline most appropriate criteria and their operating conditions are named by adding as a link in the supply chain, which is based on lower costs and delivery period.Анализируется, во что обходится и из каких затрат складывается хранение жидкого топлива в портовых и береговых терминалах, участвующих в грузоперевозках. В числе прочего оцениваются выбор рациональных объемов резервуаров, окупаемость постройки буферных емкостей, стоимость нахождения одной тонны сырой нефти, мазута, дизельного топлива в сутки, перевозка подобных грузов в осенне-зимний и весеннелетний периоды по определенным маршрутам. Названы на основе показателей терминалов российской береговой линии наиболее приемлемые критерии и условия их эксплуатации при включении в качестве звена в логистической цепи, ориентированного на меньшие затраты и сроки доставки
Dynamic model of elastoplastic normal collision of spherical particles under nonlocal plasticity
The problem of normal collision of a spherical particle with a half-space is considered with allowance for nonlocal plastic deformation in the case where the strength limit depends on the contact radius, as well as for the strengthening effect in the deformed material. The dimensionless coefficient of normal velocity restitution has been calculated numerically as a function of the initial velocity of the spherical particle. The obtained data coincide well with experimental results available in the literature
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