scholarly journals Oscillatory thermocapillary instability of a film heated by a thick substrate

2019 ◽  
Vol 872 ◽  
pp. 928-962 ◽  
Author(s):  
W. Batson ◽  
L. J. Cummings ◽  
D. Shirokoff ◽  
L. Kondic
Keyword(s):  
Eigenvalue Problem ◽  
Nonlinear Partial Differential Equation ◽  
Solid Substrate ◽  
Thermal Conductivity Ratio ◽  
Model Parameters ◽  
Substrate Thickness ◽  
Quiescent State ◽  
Thermocapillary Instability ◽  
Thick Substrate ◽  
Oscillatory Instabilities

In this work we consider a new class of oscillatory instabilities that pertain to thermocapillary destabilization of a liquid film heated by a solid substrate. We assume the substrate thickness and substrate–film thermal conductivity ratio are large so that the effect of substrate thermal diffusion is retained at leading order in the long-wave approximation. As a result, the system dynamics is described by a nonlinear partial differential equation for the film thickness that is non-locally coupled to the full substrate heat equation. Perturbing about a steady quiescent state, we find that its stability is described by a non-self-adjoint eigenvalue problem. We show that, under appropriate model parameters, the linearized eigenvalue problem admits complex eigenvalues that physically correspond to oscillatory (in time) instabilities of the thin-film height. As the principal results of our work, we provide a complete picture of the susceptibility to oscillatory instabilities for different model parameters. Using this description, we conclude that oscillatory instabilities are more relevant experimentally for films heated by insulating substrates. Furthermore, we show that oscillatory instability where the fastest-growing (most unstable) wavenumber is complex, arises only for systems with sufficiently large substrate thicknesses. Finally, we discuss adaptation of our model to a practical setting and make predictions of conditions at which the reported instabilities can be observed.

Conjugate Heat Transfer in Single-Phase Wavy Microchannel

2016 ◽  
Author(s):  
Nishant Tiwari ◽  
Manoj Kumar Moharana ◽  
Sunil Kumar Sarangi
Keyword(s):  
Heat Transfer ◽  
Cross Section ◽  
Flow Rate ◽  
Conjugate Heat Transfer ◽  
Numerical Study ◽  
Local Heat Transfer ◽  
Solid Substrate ◽  
Channel Cross Section ◽  
Thermal Conductivity Ratio ◽  
Substrate Thickness

A three-dimensional numerical study has been carried out to understand the effect of axial wall conduction in a conjugate heat transfer situation in a wavy wall square cross section microchannel engraved on solid substrate whose thickness varying between 1.2–3.6 mm. The bottom of the substrate (1.8 × 30 mm2) is subjected to constant wall heat flux while remaining faces exposed to ambient are assumed to be adiabatic. The vertical parallel walls are considered wavy such that the channel cross section at any axial location will be a square (0.6 × 0.6 mm2) and length of the channel is 30 mm. Wavelength (λ) and amplitude (A) of the wavy channel wall are 12 mm and 0.2 mm respectively. Simulations has been carried out for substrate thickness to channel depth ratio (δsf ∼ 1–5), substrate wall to fluid thermal conductivity ratio (ksf ∼ 0.34–646) and flow rate (Re ∼ 100 to 500). The results show that with increase in flow rate (Re), the hydrodynamic and thermal boundary layers are thinned due to wavy passage and they shifted from the centerline towards the peak which improves the local heat transfer coefficient at the solid-fluid interface. It is also found that after attaining maximum Nuavg at optimum ksf, the slope goes downward with increasing ksf for all set of δsf and flow rate (Re) considered in this study.

Odd-viscosity-induced stabilization of viscous thin liquid films

2019 ◽  
Vol 878 ◽  
pp. 169-189
Author(s):  
E. Kirkinis ◽  
A. V. Andreev
Keyword(s):  
Evolution Equation ◽  
Liquid Films ◽  
Solid Substrate ◽  
Capillary Waves ◽  
Thin Liquid Films ◽  
Shear Stresses ◽  
Thermocapillary Effect ◽  
Surface Shear ◽  
Thermocapillary Instability ◽  
Parameter Ranges

Thin viscous liquid films sitting on a solid substrate support nonlinear capillary waves, driven by surface shear stresses at a liquid–gas interface. When surface tension is spatially dependent other mechanisms, such as the thermocapillary effect, influence the dynamics of thin films. In this article we show that in liquids with broken time-reversal symmetry the character of the aforementioned waves and of the thermocapillary effect are significantly modified due to the presence of odd or Hall viscosity in the liquid. This is because odd viscosity gives rise to new terms in the pressure gradient of the flow thus modifying the evolution equation of the liquid–gas interface accordingly. These terms in turn break the reflection symmetry of the evolution equation leading the system to evolve from a pitchfork to a Hopf bifurcation. The odd-viscosity incipient waves can stabilize unstable thin liquid films. For instance, we show that they can suppress the thermocapillary instability. We establish the parameter ranges that odd viscosity has to satisfy in order to initiate those waves that will lead to stability.

scholarly journals Leptonic modelling of Ton 599 in flare and quiescent states

2019 ◽  
Vol 492 (1) ◽  
pp. 72-78
Author(s):  
S R Patel ◽  
V R Chitnis
Keyword(s):  
Dynamic Range ◽  
Spectral Energy Distribution ◽  
Broad Band ◽  
Spectral Energy ◽  
Model Parameters ◽  
Quiescent State ◽  
High Flux ◽  
Two Component ◽  
Γ Ray ◽  
Flux State

ABSTRACT The flat-spectrum radio quasar Ton 599 attained its highest ever γ-ray flux state during the first week of 2017 November. Observations of the source by the Swift satellite during this period made it possible to generate a simultaneous high flux state broad-band spectral energy distribution (SED). The high flux state activity of Ton 599 is modelled in this work for the first time. We modelled one high flux state and one quiescent state of the source in order to characterize the evolution of SEDs covering the entire dynamic range of γ-ray flux observed by Fermi-LAT. An attempt was made to model the 2017 November state of the source using an external Compton (EC) model in the leptonic scenario. We reproduce the broad-band flaring state SED using a two-component leptonic emission model. We considered one component as an EC+synchrotron self-Compton (SSC) component and the other as pure SSC, lying further down in the jet. The EC+SSC component was located outside the broad-line region (BLR). It mainly reproduces the GeV emission by an EC process with a dusty torus (DT) photon field providing seed photons. We reproduce the broad-band emission from Ton 599 satisfactorily during its peculiar flaring state with a leptonic two-component model. Besides this, we compare the model parameters of a quiescent-state SED with the available average state model parameters in the literature.

scholarly journals Differential response to cytotoxic therapy explains treatment dynamics of AML patients: insights from a mathematical modelling approach

2020 ◽  
Author(s):  
H. Hoffmann ◽  
C. Thiede ◽  
I. Glauche ◽  
M. Bornhaeuser ◽  
I. Roeder
Keyword(s):  
Leukemic Cells ◽  
Individual Risk ◽  
Individual Treatment ◽  
Model Parameters ◽  
Quiescent State ◽  
Early Assessment ◽  
Hematopoietic Stem ◽  
Disease Response ◽  
Early Relapse ◽  
The Individual

AbstractDisease response and durability of remission are very heterogeneous in patients with acute myeloid leukaemia (AML) patients. There is increasing evidence that the individual risk of early relapse can be predicted based on the initial treatment response. However, it is unclear how such a correlation is linked to functional aspects of AML progression and treatment. We suggest a mathematical model in which leukaemia-initiating cells and normal/healthy hematopoietic stem and progenitor cells reversibly change between an active state characterized by proliferation and chemosensitivity and a quiescent state, in which the cells do not divide, but are also insensitive to chemotherapy. Applying this model to 275 molecular time courses of NPM1-mutated patients, we conclude that the differential chemosensitivity of the leukaemia-initiating cells together with the cells’ intrinsic proliferative capacity is sufficient to reproduce both, early relapse as well as long-lasting remission. We can, furthermore, show that the model parameters associated with individual chemosensitivity and proliferative advantage of the leukemic cells are closely linked to the patients’ time to relapse. They can, therefore, be used as a measure of the aggressiveness of the disease. Early assessment of these measures and incorporation into risk stratification schemes will improve risk assessment and individual treatment in AML.

scholarly journals Optimization of BS4 Enzyme production with Different Substrate Thickness and Type of Trays

2019 ◽  
Vol 24 (4) ◽  
pp. 158
Author(s):  
Tuti Haryati ◽  
Arnold P Sinurat ◽  
H Hamid ◽  
Tresnawati Purwadaria
Keyword(s):  
Palm Kernel ◽  
Solid Substrate ◽  
Feed Additive ◽  
Substrate Thickness ◽  
Dry Matter Loss ◽  
Perforated Tray ◽  
Randomized Design ◽  
Tray Bioreactor ◽  
Mannanase Activity ◽  
The Cost

BS4 enzyme that is produced from solid substrate fermentation (SSF) on coconut cake with Eupenicillium javanicum BS4 in tray bioreactor has been applied as a feed additive. It increases the nutritional value of animal feedstuff. The BS4 production on SSF may be influenced by the better aeration through the perforated trays or by the thinner substrate. The aim of this research is to optimize the production of BS4 with different substrate thicknesses and types of trays. The trial was carried out using a factorial randomized design (2x2x3) with 6 replicates. The first factor was the type of trays: i.e., non-perforated and perforated tray. The second factor was the thickness of the substrate: i.e., 1.5 and 3.0 cm, while the third factor was the duration of fermentation: i.e. 5, and 7 days. The variables observed were moisture content, dry matter loss (DML), mannanase and saccharification activities, soluble protein content, their specific activities, and yield. Statistical analysis showed no interactions between the three factors, but there were interactions between types of trays and substrate thicknesses, as well as type of trays and incubation times on the mannanase activity and yield of mannanase. The results showed that DML was observed on day 7 were around 31.43- 36.89. The highest mannanase activity was observed on the non-perforated tray with 3 cm thickness on day 7. The saccharification activity towards palm kernel meal was better in the non-perforated tray on day 7 but not influenced by The yield value of mannanase and saccharification activities on a non-perforated tray with 3.0 cm thickness on day 7 was also the highest. Based on energy efficiency and the cost of production, it can be concluded that the optimum condition to produce the BS4 enzyme was observed in the non-perforated tray with 3 cm thickness and fermented for 7 days.

The Impact of the Electronic Skin Substrate on the Robotic Tactile Sensing

2019 ◽  
Vol 16 (05) ◽  
pp. 1950026
Author(s):  
Chuhao Chen ◽  
Houde Liu ◽  
Xiaojun Zhu ◽  
Dezhi Wu ◽  
Yu Xie
Keyword(s):  
Elastic Modulus ◽  
Force Distribution ◽  
Tactile Sensing ◽  
Substrate Thickness ◽  
Electronic Skin ◽  
Significant Interest ◽  
Thick Substrate ◽  
Cognitive Robots ◽  
The Impact ◽  
Sensing Performance

The tactile sensing is of significant interest for coexisting-cooperative-cognitive robots (Tri-Co robots). In order to improve the tactile sensing performance of the robot via an electronic skin (e-skin), an auxiliary elastomeric substrate is required. This paper investigates the effect of the substrate including elastic modulus, thickness and location on the static sensing at first. It is found that thick substrate with small elastic modulus can even the force distribution effectively and improve the contact area sensing. But it brought noises and crosstalk on the e-skin when the substrate has the large deformation. In occasions of dynamic tactile sensing, the impact of substrate thickness and elastic modulus was also studied and it is found that smaller elastic modulus can help e-skin sense larger and higher frequency stimulus.

scholarly journals Diameter and Proper Motion of Sgr A∗

1996 ◽  
Vol 169 ◽  
pp. 193-198
Author(s):  
D. C. Backer
Keyword(s):  
Energy Source ◽  
Accretion Rate ◽  
Model Parameters ◽  
Quiescent State ◽  
Massive Black Hole ◽  
General Hypothesis ◽  
Sagittarius A ◽  
Nonthermal Radio ◽  
Sgr A ◽  
Ultimate Fate

The best hypothesis for the energy source of the compact, nonthermal radio source in the center of our galaxy, Sagittarius A∗ (Sgr A∗), is accretion onto a massive black hole from winds emanating from nearby luminous stars. The hole mass, accretion rate, and ultimate fate of accreted matter are uncertain. In this report I give a summary of recent critical observations. The interpretation of these results supports this general hypothesis, and begins to place constraints on model parameters. If so, then Sgr A∗ is a miniature version of extragalactic AGNs in a quiescent state.

scholarly journals STUDY ON THE INFLUENCE OF ELECTROPHYSICAL CHARACTERISTICS ON THE PARAMETERS OF COMPACT MODELS OF THE COMPONENTS USED IN RADIO FREQUENCY MONOLITHIC INTEGRATED CIRCUITS

2020 ◽  
Vol 257 (2) ◽  
pp. 37-46
Author(s):  
A.A. Popov ◽  
D.V. Bilevich ◽  
A.S. Salnikov Salnikov ◽  
A.A. Kalentyev
Keyword(s):  
Integrated Circuits ◽  
Equivalent Circuit Model ◽  
Model Parameters ◽  
Substrate Thickness ◽  
Active Components ◽  
Signal Model ◽  
Passive Components ◽  
Gaas Mesfet ◽  
Small Signal Model ◽  
Gate Recess

In this paper we demonstrate the results of the study on how the geometric parameters effect the model parameters of passive and active components. As we found out, the substrate thickness has the greatest influence on the equivalent circuit model parameters of passive components. Paper demonstrates the influence of the gate length and the gate recess depth on the parameters of small-signal model of the MESFET. The obtained dependences are presented for the MIM capacitor model, inductor model and GaAs MESFET model.

scholarly journals Extremely Low-Profile Monopolar Microstrip Antenna with Wide Bandwidth

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5295
Author(s):  
Youngseok Ha ◽  
Jae-il Jung ◽  
Sunghee Lee ◽  
Seongmin Pyo
Keyword(s):  
Microstrip Antenna ◽  
High Speed ◽  
Impedance Bandwidth ◽  
Substrate Thickness ◽  
Frequency Bandwidth ◽  
Broad Bandwidth ◽  
Directional Radiation ◽  
Low Profile ◽  
Thick Substrate ◽  
Symmetrical Center

In this paper, we propose a new monopolar microstrip antenna for a high-speed moving swarm sensor network. The proposed antenna shows an extremely thin substrate thickness supported with an omni-directional radiation pattern and wide operation frequency bandwidth. First, to achieve the low-profile monopolar microstrip antenna, the symmetrical center feeding network and the gap-coupled six arrayed patches which form a hexagonal microstrip radiator were utilized. The partially loaded ground-slots under the top patches were employed to improve the radiation performance and adjust the impedance bandwidth. Second, to obtain the broad bandwidth of the low-profile monopolar microstrip antenna, the degenerated non-fundamental TM02 modes, that is, even and odd TM02 modes, were carefully analyzed. To verify the feasibility of the degenerated TM02 mode operation, the parametric study of the proposed antenna was theoretically investigated and implemented with the optimized parameter dimensions. Finally, the fabricated antenna showed a 0.254 mm-thick substrate and demonstrates 1.5-wavelength resonant monopolar radiation with broad impedance bandwidth of 855 MHz and its factional bandwidth of 15.24% at the resonant frequency of 5.57 GHz.

Conidia Production by Beauveria bassiana on Rice in Solid-State Fermentation Using Tray Bioreactor

2012 ◽  
Vol 610-613 ◽  
pp. 3478-3482 ◽  
Author(s):  
Ling Xie ◽  
Hong Mei Chen ◽  
Ji Bin Yang
Keyword(s):  
Solid State ◽  
Beauveria Bassiana ◽  
Solid State Fermentation ◽  
Solid Substrate ◽  
Gas Transfer ◽  
Substrate Thickness ◽  
Average Yield ◽  
Metabolic Heat ◽  
Conidia Production ◽  
Tray Bioreactor

Conidia of Beauveria bassiana Bb-202, which have the potential for the control of the coleopteran pests, were produced on rice by solid-state fermentation (SSF) using tray bioreactor. As the solid substrate thickness increased, the production of conidia decreased. By cutting substrate into many small uniform pieces, metabolic heat and gas transfer in center of substrate could be improved. We concluded that the highest yield of 3.94×1012 conidia kg-1 rice was obtained as the substrate of 2cm thickness was cut into many small pieces (6cm×4cm×2cm). And the average yield of conidia increases by 45%. It indicated that cut solid substrate into many pieces would increasing the surface area of substrate. So the conidia yields were significantly increased.

Sign in / Sign up

Export Citation Format

Share Document