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transition-point
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Markovian approach to tackle the interaction of simultaneous diseases
, Article Physical Review E ; Volume 100, Issue 6 , 2019 ; 24700045 (ISSN) ; Ghanbarnejad, F ; Meloni, S ; Gomez Gardenes, J ; Sharif University of Technology
American Physical Society
2019
Abstract
The simultaneous emergence of several abrupt disease outbreaks or the extinction of some serotypes of multistrain diseases are fingerprints of the interaction between pathogens spreading within the same population. Here, we propose a general and versatile benchmark to address the unfolding of both cooperative and competitive interacting diseases. We characterize the explosive transitions between the disease-free and the epidemic regimes arising from the cooperation between pathogens and show the critical degree of cooperation needed for the onset of such abrupt transitions. For the competing diseases, we characterize the mutually exclusive case and derive analytically the transition point...
Exact solution of generalized cooperative susceptible-infected-removed (SIR) dynamics
, Article Physical Review E ; Volume 100, Issue 1 , 2019 ; 24700045 (ISSN) ; Moghimi Araghi, S ; Ghanbarnejad, F ; Sharif University of Technology
American Physical Society
2019
Abstract
In this paper, we introduce a general framework for coinfection as cooperative susceptible-infected-removed (SIR) dynamics. We first solve the SIR model analytically for two symmetric cooperative contagions [L. Chen, Europhys. Lett. 104, 50001 (2013)10.1209/0295-5075/104/50001] and then generalize and solve the model exactly in the symmetric scenarios for three and more cooperative contagions. We calculate the transition points and order parameters, i.e., the total number of infected hosts. We show that the behavior of the system does not change qualitatively with the inclusion of more diseases. We also show analytically that there is a saddle-node-like bifurcation for two cooperative SIR...
Effects of measures on phase transitions in two cooperative susceptible-infectious-recovered dynamics
, Article Physical Review E ; Volume 105, Issue 3 , 2022 ; 24700045 (ISSN) ; Ghanbarnejad, F ; Sharif University of Technology
American Physical Society
2022
Abstract
In recent studies, it has been shown that a cooperative interaction in a co-infection spread can lead to a discontinuous transition at a decreased threshold. Here, we investigate the effects of immunization with a rate proportional to the extent of the infection on phase transitions of a cooperative co-infection. We use the mean-field approximation to illustrate how measures that remove a portion of the susceptible compartment, like vaccination, with high enough rates can change discontinuous transitions in two coupled susceptible-infectious-recovered dynamics into continuous ones while increasing the threshold of transitions. First, we introduce vaccination with a fixed rate into a...
The role of surface wettability on the heat transfer in liquid-liquid two-phase flow in a microtube
, Article Physics of Fluids ; Volume 31, Issue 8 , 2019 ; 10706631 (ISSN) ; Kazemzadeh Hannani, S ; Farhanieh, B ; Sharif University of Technology
American Institute of Physics Inc
2019
Abstract
Liquid-liquid two-phase flow is capable of boosting heat transfer in microdevices compared to the single-phase and gas-liquid flows. A thorough investigation is performed here to characterize the heat transfer in water-oil flow in a microtube. Finite element method along with the level-set model is employed for numerical simulation. A main part of this paper is devoted to studying the effect of wettability on the heat transfer performance. Four contact angles of 0°, 30°, 150°, and 180° are investigated, which revealed that the contact angle of 150° produces the highest Nusselt number (Nu). Triple points form at this contact angle, and the slugs slide on the wall, which results in more...
A new look at tensile yielding in isotactic polypropylene: role of strain rate and thermal softening
, Article Polymer Bulletin ; Volume 79, Issue 12 , 2022 , Pages 11157-11176 ; 01700839 (ISSN) ; Bagheri, R ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
Polypropylene (PP) is a semi-crystalline polymer with a very wide range of industrial applications. This is why its mechanical properties, including yielding, have been the subject of numerous studies. The current study has examined the influence of strain rate and thermal softening on yield stress and post yielding behavior of an isotactic PP. A two-process Ree and Eyring model and the heat equation in adiabatic deformation were coupled with a physical parameter described as the temperature sensitivity of the flow stress at yielding, to simulate the effect of gradual temperature rise in adiabatic heating on yielding behavior. Along with that, tensile bars were subjected to tests at...
Characterization of constrained aged niti strips for using in artificial muscle actuators
, Article International Journal of Engineering, Transactions A: Basics ; Volume 24, Issue 4 , 2011 , Pages 321-329 ; 17281431 (ISSN) ; Sadrnezhaad, S. K ; Sharif University of Technology
Abstract
Marvelous bending/straightening effects of two-way shape memory alloy (TWSMA) help their employment in design and manufacturing of new medical appliances. Constrained ageing with bending load scheme can induce two-way shape memory effect (TWSME). Scanning electron microscopic (SEM) analysis, electrical resistivity measurement (ERM) and differential scanning calorimetry (DSC) are employed to determine the property change due to flat strip constrained aging. Results show that flat-annealing prior to the aging shifts NiTi transformations temperatures to higher values. Superelastic behavior of the as-received/flat- annealed/aged samples with more adequate transition temperatures due to...
Experimental investigation of transition on a plunging airfoil
, Article Scientia Iranica ; Volume 17, Issue 6 B , NOVEMBER-DECEMBER , 2010 , Pages 468-479 ; 10263098 (ISSN) ; Rasi Marzabadi, F ; Sharif University of Technology
2010
Abstract
Extensive tests were carried out on a section of a wind turbine blade. The effect of reduced frequency on the boundary layer transition point of the model oscillating in plunge has been investigated. The spatial-temporal progressions of the transition point and the state of the unsteady boundary layer were measured using multiple hot-film sensors. The measurements showed that reduced frequency highly affects variations of the transition point and results in a hysteresis loop in the dynamic transition locations. The dominated frequencies of the boundary layer are found to be a function of the reduced frequency and mean angle of attack
Improved adhesion of NiTi wire to silicone matrix for smart composite medical applications
, Article Materials and Design ; Volume 30, Issue 9 , 2009 , Pages 3667-3672 ; 02641275 (ISSN) ; Hassanzadeh Nemati, N ; Bagheri, R ; Sharif University of Technology
2009
Abstract
Recent uses of intelligent composites in biomedical appliances aggrandize the necessity of bonding-strength improvement in NiTi/silicone matrix interface. SEM micrographs and pull-out tests are employed to determine the strength of the NiTi/silicone bonds in a flexible composite piece. Greater adhesion strengths are obtained due to the presence of thin oxide layer, surface roughness and frictional forces between the embedded-wires and the contacting phase. Effect of curing treatment on phase transformation temperatures of the wires is determined by electrical resistivity (ER) measurements. Results show that the curing treatment shifts the transition points of the wires towards higher...
Investigation of the pressure distribution and transition point over a swept wing
, Article Scientia Iranica ; Volume 18, Issue 6 , December , 2011 , Pages 1277-1286 ; 10263098 (ISSN) ; Ghorbanian, K ; Masdari, M ; Sharif University of Technology
2011
Abstract
A series of wind tunnel tests are performed to examine the flow field over a swept wing under various conditions. The wing has a laminar flow airfoil section, similar to those of the NACA 6-series. Static pressure distributions over the upper surface of the wing, in both chordwise and spanwise directions, are measured at different angles of attack. The data is employed to predict the transition point at each chordwise section. The skewness parameter of the pressure data shows that this factor drops to zero in the transition region. A comparison of the calculated transition point on the wing surface with that obtained from the 2D computational method shows reasonable agreement over a portion...