Cure of GR-S in Thick Articles

1944 ◽  
Vol 17 (4) ◽  
pp. 984-993
Author(s):  
Ross E. Morris ◽  
Joseph W. Hollister ◽  
Paul A. Mallard
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
Laboratory Tests ◽  
Exothermic Reaction ◽  
Thin Sheets ◽  
Thin Sections ◽  
Curing Conditions ◽  
Know How ◽  
Flow Through ◽  
The Difference

Abstract Information on the relative rates of cure of GR-S stocks and similar Hevea stocks in thick sections is of interest to many rubber manufacturers. Since curing conditions for thick articles from Hevea stocks have been established, they would like to know how these conditions must be altered when GR-S stocks are used in the same applications. They could develop a GR-S stock with the same rate of cure as the Hevea stock which it replaces according to laboratory tests on comparatively thin sheets, but this agreement does not mean necessarily that thick sections cure at the same rate. The respective rates of heat flow through the rubbers must be considered. Only if the rates of heat flow as well as the curing rates of thin sections are in agreement, will the curing rates of the thick sections be equal. Juve and Garvey found that GR-S tread stocks cure faster in the center of thick sections than similar Hevea tread stocks. They were unable to explain this behavior because, according to their measurements, the thermal conductivity of the GR-S tread stock was less, and its specific heat greater than, the corresponding values for the Hevea tread stock. They concluded that the difference mav be due to an exothermic reaction.

scholarly journals Fe Melting Transition: Electrical Resistivity, Thermal Conductivity, and Heat Flow at the Inner Core Boundaries of Mercury and Ganymede

Crystals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 359 ◽  
Author(s):  
Innocent C. Ezenwa ◽  
Richard A. Secco
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Heat Flow ◽  
Inner Core ◽  
Outer Core ◽  
Melting Transition ◽  
Planetary Bodies ◽  
Core Boundary ◽  
The Difference ◽  
Electronic Scattering

The electrical resistivity and thermal conductivity behavior of Fe at core conditions are important for understanding planetary interior thermal evolution as well as characterizing the generation and sustainability of planetary dynamos. We discuss the electrical resistivity and thermal conductivity of Fe, Co, and Ni at the solid–liquid melting transition using experimental data from previous studies at 1 atm and at high pressures. With increasing pressure, the increasing difference in the change in resistivity of these metals on melting is interpreted as due to decreasing paramagnon-induced electronic scattering contribution to the total electronic scattering. At the melting transition of Fe, we show that the difference in the value of the thermal conductivity on the solid and liquid sides increases with increasing pressure. At a pure Fe inner core boundary of Mercury and Ganymede at ~5 GPa and ~9 GPa, respectively, our analyses suggest that the thermal conductivity of the solid inner core of small terrestrial planetary bodies should be higher than that of the liquid outer core. We found that the thermal conductivity difference on the solid and liquid sides of Mercury’s inner core boundary is ~2 W(mK)−1. This translates into an excess of total adiabatic heat flow of ~0.01–0.02 TW on the inner core side, depending on the relative size of inner and outer core. For a pure Fe Ganymede inner core, the difference in thermal conductivity is ~7 W(mK)−1, corresponding to an excess of total adiabatic heat flow of ~0.02 TW on the inner core side of the boundary. The mismatch in conducted heat across the solid and liquid sides of the inner core boundary in both planetary bodies appears to be insignificant in terms of generating thermal convection in their outer cores to power an internal dynamo suggesting that chemical composition is important.

scholarly journals Avoiding Being Trapped in False Analogical Modeling of Composite Wall Thermal Resistance

2018 ◽  
Vol 1 (2) ◽  
pp. 69-77
Author(s):  
Mohammed Aliedeh*
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Flow ◽  
Thermal Resistance ◽  
Detailed Calculation ◽  
True Value ◽  
Parallel Wall ◽  
Composite Wall ◽  
The Difference ◽  
Composite Walls

Because Analogy is considered as a double-edged sword, thermal engineers should be cautious in analogical maneuvering between electrical and thermal domains in order not to be slipped into building misconceptions about thermal resistance concept. Composite wall thermal resistance (CWTR) modeling is one of the practical examples that illustrates the probability of misusing analogy. Heat transfer undergraduate textbooks coverage of CWTR suffers a lean towards “cookbook” coverage that reports concise statements that lack deep clarification and illustration. Transparent Thinking Approach (TTA) is employed to present a detailed calculation and illustration of a typical CWTR modeling based on isothermal and adiabatic assumptions. The calculation of a typical CWTR for different values of wall thermal conductivities shows that the difference in parallel walls thermal conductivity is creating a large discrepancy that may reach 80% between heat flows calculated based on isothermal and adiabatic assumptions. It is found that for a series-parallel arrangement of composite walls with high difference in parallel wall thermal conductivity values, the true value of heat flow is bracketed between the isothermal and adiabatic heat flow values. The transparent way of presenting CWTR modeling can be readily included in any standard heat transfer textbook and result in greatly enhancing CWTR modeling coverage.

scholarly journals Mars Regolith Properties as Constrained from HP3 Mole Operations and Thermal Measurements

2020 ◽  
Author(s):  
Tilman Spohn ◽  
Matthias Grott ◽  
Nils Müller ◽  
Jörg Knollenberg ◽  
Christian Krause ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Lower Bound ◽  
Heat Flow ◽  
Thermal Inertia ◽  
Geothermal Gradient ◽  
Thermal Measurements ◽  
Initial Penetration ◽  
Flow Through ◽  
Homogeneous Soil ◽  
Insight Mission

<p>The Heat Flow and Physical Properties Package HP<sup>3</sup> onboard the Nasa InSight mission has been on the surface of Mars for more than one Earth year. The instrument's primary goal is to measure Mars' surface heat flow through measuring the geothermal gradient and the thermal condunctivity at depths between 3 and 5m. To get to depth, the package includes a penetrator nicknamed the "Mole"  equipped with sensors to precisely measure the thermal conductivity. The Mole tows a tether with printed temperature sensors;  a device to measure the length of the tether towed and a tiltmeter will help to track the path of the Mole and the tether. Progress of the Mole has been stymied by difficulties of digging into the regolith. The Mole functions as a mechanical diode with an internal hammer mechanism that drives it forward. Recoil is balanced mostly by internal masses but a remaining 3 to 5N has to be absorbed by hull friction. The Mole was designed to work in cohesionless sand but at the InSight landing a cohesive duricrust of at least 7cm thickness but possibly 20cm thick was found. Upon initial penetration to 35cm depth, the Mole punched a hole about 6cm wide and 7cm deep into the duricrust, leaving more than a fourth of its length without hull friction.  It is widely agreed that the lack of friction is the reason for the failure to penetrate further. The HP<sup>3</sup> team has since used the robotic arm with its scoop to pin the Mole to the wall of the hole and helped it penetrate further to almost 40cm. The initial penetration rate of the Mole has been used to estimate a penetration resistance of 300kPa. Attempts to crush the duricrust a few cm away from the pit have been unsuccessful from which a lower bound to the compressive strength of 350kPa is estimated.  Analysis of the slope of the steep walls of the hole gave a lower bound to cohesion of 10kPa. As for thermal properties, a measurement of the thermal conductivity of the regolith with the Mole thermal sensors resulted in 0.045 Wm<sup>-1</sup>K<sup>-1</sup>.  The value is considerably uncertain because part of the Mole having contact to air.  The HP³ radiometer has been monitoring the surface temperature next to the lander and a thermal model fitted to the data give a regolith thermal inertia of  189 ± 10 J m<sup>-2</sup> K<sup>-1</sup> s<sup>-1/2</sup>. With best estimates of heat capacity and density, this corresponds to a thermal conductivity of 0.045 Wm<sup>-1</sup>K<sup>-1</sup>, consistent with the above measurement using the Mole. The data can be fitted well with a homogeneous soil model, but observations of Phobos eclipses in March 2019 indicate that there possibly is a thin top layer of lower thermal conductivity. A model with a top 5 mm layer of 0.02 Wm-1K-1 above a half-space of 0.05 Wm-1K-1 matches the amplitudes of both the diurnal and eclipse temperature curves. Another set of eclipses will occur in April 2020.</p><p> </p>

AN INSTRUMENT FOR MEASURING HEAT FLOW, TEMPERATURE, AND THERMAL CONDUCTIVITY IN THE LUNAR SURFACE LAYER

1970 ◽  
Author(s):  
A. E. Wechsler ◽  
E. M. Drake ◽  
F. E. Ruccia ◽  
J. E. McCullough ◽  
P. Felsenthal ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Surface Layer ◽  
Heat Flow ◽  
Lunar Surface ◽  
Flow Temperature

DISTINGUISHING THE INDISTINGUISHABLE OF THE WORDS INJURED, WOUNDED, AND HURT: A CORPUS INVESTIGATION

2017 ◽  
Vol 24 (1) ◽  
pp. 19
Author(s):  
Kusumawardani Dewa Ayu Novi
Keyword(s):  
English Word ◽  
Know How ◽  
Efl Students ◽  
The Difference

Most people, especially EFL students, claimed that English has rich vocabularies. Each vocabulary has many synonyms that could be found in thesaurus. But the problem is, those synonymous words can hardly be differentiated when applied in daily communication. It is because each of the English word has its own context and rule when it is used in a sentence or an utterance. However, in reality, this rule is often ignored by people. It is because they rely more on their intuition. Yet, it needs more than intuition to know the difference and how to use the words properly. The words ‘injured’, ‘wounded’, and ‘hurt’ were chosen as the object of this study, since those words are synonymous and distinguishable. A quick survey had been done by the researcher to know how EFL students and people in general used these three words. It turned out that they used those three words by ignoring the rule and depending on their intuition instead. The aim of this research is to help people to know the difference among those three words. By retrieving data from COCA and finding the collocation of those words, it is hoped that the reader will realize that these synonymous words are not as synonymous as they thought.

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