Temperature Synchronization, Phase Dynamics and Oscillation Death in a Ring of Thermally-Coupled Rooms

2011 ◽  
Author(s):  
Jeffrey O’Brien ◽  
Mihir Sen
Keyword(s):  
Room Temperature ◽  
Independent Solution ◽  
Thermal Coupling ◽  
System Of Differential Equations ◽  
Thermostatic Control ◽  
Phase Dynamics ◽  
Temperature Oscillations ◽  
Solution Type ◽  
Synchronization Phase ◽  
Differential Equations Models

Synchronization of coupled, self-excited oscillators in complex systems is a common occurance. This report examines the effects of thermal coupling through the walls of a building on temperature oscillations due to hysteretic thermostatic control. The specific case of three rooms is studied. A system of differential equations models the dynamics of each room temperature, accounting for on-off heating, heat loss to the environment, and heat exchange between rooms. Three types of solutions are observed: one in which all room temperatures oscillate in phase, another with the oscillations equidistant in phase, and a third that is time-independent. The existence and linear stability of each solution type is investigated as a function of a parameter k that represents the thermal interaction between neighboring rooms. The in-phase behavior exists and is linearly stable for all k, the out-of-phase oscillations exist in a band of k and are stable in a smaller band, and the time-independent solution exists above a certain k where they are stable.

Room-Temperature oscillations in a superlattice structure

1986 ◽  
Vol 22 (3) ◽  
pp. 131 ◽  
Author(s):  
R.A. Davies ◽  
P.H. Beaton ◽  
M.J. Kelly ◽  
T.M. Kerr
Keyword(s):  
Room Temperature ◽  
Superlattice Structure ◽  
Temperature Oscillations

scholarly journals Synchronization in a coupled two-layer quasigeostrophic model of baroclinic instability – Part 1: Master-slave configuration

2009 ◽  
Vol 16 (4) ◽  
pp. 543-556
Author(s):  
A. A. Castrejón-Pita ◽  
P. L. Read
Keyword(s):  
Phase Synchronization ◽  
Baroclinic Instability ◽  
Coupled System ◽  
Zonal Flow ◽  
Chaotic Regime ◽  
Phase Dynamics ◽  
Show Evidence ◽  
Synchronization Phase ◽  
Quasigeostrophic Model ◽  
Phase Slips

Abstract. Synchronization is studied using a pair of diffusively-coupled, two-layer quasi-geostrophic systems each comprising a single baroclinic wave and a zonal flow. In particular, the coupling between the systems is in the well-known master-slave or one-way configuration. Nonlinear time series analysis, phase dynamics, and bifurcation diagrams are used to study the dynamics of the coupled system. Phase synchronization, imperfect synchronization (phase slips), or complete synchronization are found, depending upon the strength of coupling, when the systems are either in a periodic or a chaotic regime. The results of investigations when the dynamics of each system are in different regimes are also presented. These results also show evidence of phase synchronization and signs of chaos control.

Direct methods in protein electron crystallography – beef liver catalase in its fully hydrated form at room temperature

1999 ◽  
Vol 55 (3) ◽  
pp. 448-456 ◽  
Author(s):  
Douglas L. Dorset ◽  
Christopher J. Gilmore
Keyword(s):  
Room Temperature ◽  
Independent Solution ◽  
Direct Methods ◽  
Basis Set ◽  
Electron Diffraction Data ◽  
Electron Crystallography ◽  
Good Match ◽  
Beef Liver ◽  
Hydrated Form ◽  
Resolution Structure

The crystal structure of beef liver catalase was determined ab initio in projection to 9 Å resolution using electron diffraction data at room temperature from hydrated specimens maintained in an environmental chamber in the electron microscope. A conservative combination of symbolic addition with maximum entropy and likelihood led to a model with a Patterson correlation coefficient C = 0.89 to the observed data. This independent solution could then be compared favorably to a previous 23 Å analysis of electron micrographs from frozen hydrated preparations. Prediction of the higher-resolution structure by extension of the lower-resolution image-based phase basis set also gave a good match to the direct-methods solution, particularly for the most intense reflections.

scholarly journals Experimental Measurements on the Thermal Conductivity of Glycerol-Based Nanofluids with Different Thermal Contrasts

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Mohamed Lotfi ◽  
Rodolphe Heyd ◽  
Abderrahim Bakak ◽  
Abdellah Hadaoui ◽  
Abdelaziz Koumina
Keyword(s):  
Thermal Conductivity ◽  
Room Temperature ◽  
Volume Fraction ◽  
High Viscosity ◽  
Copper Oxides ◽  
Nanoparticle Volume Fraction ◽  
Graphene Flake ◽  
Temperature Oscillations ◽  
Graphene Flakes ◽  
3Ω Technique

We report, in this work, our study of the thermal conductivity of high-viscosity nanofluids based on glycerol. Three nanofluids have been prepared with different thermal contrasts, by suspending graphene flakes, copper oxides, or silica nanoparticles in pure glycerol. The nanofluids were thermally characterized at room temperature with the 3ω technique, with low amplitudes of the temperature oscillations. A significant enhancement of the thermal conductivity is found in both the glycerol/copper oxide and the glycerol/graphene flake nanofluids. Our results question the role played by the Brownian motion in the microscopic mechanisms of the thermal conductivity of high-viscosity glycerol-based nanofluids. A similar behavior of the thermal conductivity as a function of the nanoparticle volume fraction was found for all three glycerol-based nanofluids presently investigated. These results could be explained on the basis of fractal aggregation in the nanofluids.

scholarly journals Phase-response analysis of synchronization for periodic flows

2018 ◽  
Vol 846 ◽  
Author(s):  
Kunihiko Taira ◽  
Hiroya Nakao
Keyword(s):  
Fluid Flows ◽  
Phase Response ◽  
Response Analysis ◽  
Phase Variable ◽  
External Forcing ◽  
Cylinder Wake ◽  
Periodic Flows ◽  
Phase Dynamics ◽  
Phase Reduction ◽  
Synchronization Phase

We apply phase-reduction analysis to examine synchronization properties of periodic fluid flows. The dynamics of unsteady flows is described in terms of the phase dynamics, reducing the high-dimensional fluid flow to its single scalar phase variable. We characterize the phase response to impulse perturbations, which can in turn quantify the influence of periodic perturbations on the unsteady flow. These insights from phase-based analysis uncover the condition for synchronization. In the present work, we study as an example the influence of periodic external forcing on an unsteady cylinder wake. The condition for synchronization is identified and agrees closely with results from direct numerical simulations. Moreover, the analysis reveals the optimal forcing direction for synchronization. Phase-response analysis holds potential to uncover lock-on characteristics for a range of periodic flows.

Dependence of Intergranular Fracture on Boundary Topography and Cohesion

1973 ◽  
Vol 31 ◽  
pp. 150-151
Author(s):  
J. E. Doherty ◽  
A. F. Giamei ◽  
B. H. Kear ◽  
C. W. Steinke
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Nickel Base Superalloy ◽  
Boundary Shear ◽  
Room Temperature Ductility ◽  
Solid Solution Matrix ◽  
Nickel Base ◽  
Solution Matrix ◽  
Different Levels ◽  
Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

Hepatocyte Alterations in Guinea Pigs FED Polychlorinated Biphenyls (PCBs), Dibenzodioxins (PCDD), AND DIBENZOFURANS (PCDF)

1982 ◽  
Vol 40 ◽  
pp. 56-57
Author(s):  
J. N. Turner ◽  
D. N. Collins
Keyword(s):  
Guinea Pigs ◽  
Room Temperature ◽  
Dose Group ◽  
Methyl Cellulose ◽  
Uranyl Acetate ◽  
Target Organ ◽  
Office Building ◽  
Lead Citrate ◽  
Control Groups ◽  
Cooling Fluid

A fire involving an electric service transformer and its cooling fluid, a mixture of PCBs and chlorinated benzenes, contaminated an office building with a fine soot. Chemical analysis showed PCDDs and PCDFs including the highly toxic tetra isomers. Guinea pigs were chosen as an experimental animal to test the soot's toxicity because of their sensitivity to these compounds, and the liver was examined because it is a target organ. The soot was suspended in 0.75% methyl cellulose and administered in a single dose by gavage at levels of 1,10,100, and 500mgm soot/kgm body weight. Each dose group was composed of 6 males and 6 females. Control groups included 12 (6 male, 6 female) animals fed activated carbon in methyl cellulose, 6 males fed methyl cellulose, and 16 males and 10 females untreated. The guinea pigs were sacrificed at 42 days by suffocation in CO2. Liver samples were immediately immersed and minced in 2% gluteraldehyde in cacadylate buffer at pH 7.4 and 4°C. After overnight fixation, samples were postfixed in 1% OsO4 in cacodylate for 1 hr at room temperature, embedded in epon, sectioned and stained with uranyl acetate and lead citrate.

Domain Formation in Synthetic Quartz

1971 ◽  
Vol 29 ◽  
pp. 156-157
Author(s):  
Joseph J. Comer
Keyword(s):  
Electron Beam ◽  
Room Temperature ◽  
Domain Formation ◽  
Synthetic Quartz ◽  
Transmission Electron ◽  
Black Spots ◽  
Diffraction Mode ◽  
Domain Boundaries ◽  
Kikuchi Lines ◽  
Straight Lines

Domains visible by transmission electron microscopy, believed to be Dauphiné inversion twins, were found in some specimens of synthetic quartz heated to 680°C and cooled to room temperature. With the electron beam close to parallel to the [0001] direction the domain boundaries appeared as straight lines normal to <100> and <410> or <510> directions. In the selected area diffraction mode, a shift of the Kikuchi lines was observed when the electron beam was made to traverse the specimen across a boundary. This shift indicates a change in orientation which accounts for the visibility of the domain by diffraction contrast when the specimen is tilted. Upon exposure to a 100 KV electron beam with a flux of 5x 1018 electrons/cm2sec the boundaries are rapidly decorated by radiation damage centers appearing as black spots. Similar crystallographio boundaries were sometimes found in unannealed (0001) quartz damaged by electrons.

A Liquid Nitrogen Cooled Stage for STEM

1974 ◽  
Vol 32 ◽  
pp. 444-445
Author(s):  
Louis T. Germinario
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Liquid Nitrogen ◽  
Room Temperature ◽  
Objective Lens ◽  
Thermal Drift ◽  
Specimen Holder ◽  
Resolution Capability ◽  
Focal Position

A liquid nitrogen stage has been developed for the JEOL JEM-100B electron microscope equipped with a scanning attachment. The design is a modification of the standard JEM-100B SEM specimen holder with specimen cooling to any temperatures In the range ~ 55°K to room temperature. Since the specimen plane is maintained at the ‘high resolution’ focal position of the objective lens and ‘bumping’ and thermal drift la minimized by supercooling the liquid nitrogen, the high resolution capability of the microscope is maintained (Fig.4).

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