The Rubber Pendulum, the Joule Effect, and the Dynamic Stress-Strain Curve

1935 ◽  
Vol 8 (2) ◽  
pp. 151-173 ◽  
Author(s):  
W. B. Wiegand ◽  
J. W. Snyder
Keyword(s):  
Strain Curve ◽  
Electric Heating ◽  
Radiant Heat ◽  
Rubber Band ◽  
The Other ◽  
General Description ◽  
Joule Effect ◽  
Heat Engines ◽  
Metal Shield ◽  
Original Length

Abstract General Description.—The rubber pendulum is one of two devices (Wiegand, Trans. Inst. Rubber Ind., 1, 141 (1925)) which, by employing the Joule effect, constitute rubber heat engines in that they continuously convert heat into mechanical work. In Fig. 1 is shown the original pendulum. It consists of an ordinary pendulum of slow period fitted with a rubber band, one end of which is attached to the bob; the other to the upright support. This rubber band is stretched to four or five times its original length. Behind the upright is a metal shield so arranged that when the bob has reached the extremity of its swing the rubber band is clear of the shield, during the rest of the oscillation being in its shadow. Behind the pendulum and shield is an electric heating element with a copper reflector. The pendulum is started by displacement from the center towards one or other extremity. As this is done the rubber band is increased in length. At the extremity of the oscillation the stretch band is exposed to the radiant heat from the element, the Joule effect is brought into play and the band tends to shrink, thus pulling back the bob. Directly the band moves back within the shadow of the shield it cools, relaxes, and so allows the bob to swing out to the other side. Thereupon the band is once more heated up, contracts and so repeats the oscillation, which continues as long as the heat energy is supplied. When the electric current is turned off the pendulum dies down.

A Mathematical Treatment of a Theory of Rubber Structure

1935 ◽  
Vol 8 (1) ◽  
pp. 23-38
Author(s):  
T. R. Griffith
Keyword(s):  
Elastic Modulus ◽  
Plastic Flow ◽  
Strain Curve ◽  
The Other ◽  
Stress Axis ◽  
Mathematical Treatment ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Joule Effect ◽  
Vulcanized Rubber

Abstract A brief consideration of the work that has been done on the structure of rubber convinces, one that the elasticity is wholly or at least mainly explained by a consideration of the kinetics involved. The fact that when a strip of stretched rubber, one end of which is free, contracts when it is warmed, contrary to the behavior of most bodies, and that it becomes warmed on stretching, commonly known as the Gough-Joule effect, pp. 453–461, would lead one to suspect .that there is a connection between the kinetic energy of the rubber molecule and its elasticity. Lundal, Bouasse, Hyde, Somerville and Cope, Partenheimer and Whitby and Katz have reported observations, principally stress-strain curves, which show that vulcanized rubber has a lower modulus of elasticity at higher temperatures, i. e., it becomes easier to stretch as the temperature is raised. On the other hand, Schmulewitsch, Stevens, and Williams found that the elastic modulus increases with the temperature. Williams shows that the softening of vulcanized rubber with rise of temperature is due to an increase of plasticity. In order to get rid of plastic flow, he first stretches the specimen several times to within about 50 per cent of its breaking elongation, and then obtains an autographic stress-strain curve of the rubber stretched very quickly. He finds that in this case the rubber actually becomes stiffer with rise of temperature, increasing temperatures causing the stress-strain curves to lean progressively more and more toward the stress axis. He concludes that rise of temperature has two effects, one a softening due to increase of plasticity, rendering plastic flow more easy, the other an actual stiffening of the rubber due to rise of temperature. It is not easy to explain the latter effect on any theory which does not take kinetics into account.

THEORETICAL ANALYSIS AND EXPERIMENT OF A NOVEL DEP CHIP WITH 3-D SILICON ELECTRODES

2005 ◽  
Vol 15 (02) ◽  
pp. 231-236 ◽  
Author(s):  
LIMING YU ◽  
FRANCIS E. H. TAY ◽  
GUOLIN XU ◽  
CIPRIAN ILIESCU ◽  
MARIOARA AVRAM
Keyword(s):  
Theoretical Analysis ◽  
Applied Voltage ◽  
Microfluidic Channel ◽  
The Other ◽  
Yeast Cells ◽  
Applied Potential ◽  
Dielectrophoretic Force ◽  
Joule Effect ◽  
Doped Silicon ◽  
Planar Electrodes

This paper presents a novel dielectrophoresis (DEP) device where the DEP electrodes define the channel walls. This is achieved by fabricating microfluidic channel walls from highly doped silicon so that they can also function as DEP electrodes. Compared with planar electrodes, this device increases the exhibited dielectrophoretic force on the particle, therefore decreases the applied potential and reduces the heating of the solution. A DEP device with triangle electrodes has been designed and fabricated. Compared with the other two configurations, semi-circular and square, triangle electrode presents an increased force, which can decrease the applied voltage and reduce the Joule effect. Yeast cells have been used to for testing the performance of the device.

scholarly journals Note on terrestrial radiation

1883 ◽  
Vol 35 (224-226) ◽  
pp. 21-25
Keyword(s):  
Radiant Heat ◽  
The Other ◽  
Cotton Wool ◽  
The Earth ◽  
Meteorological Observations

On Hind Head, a fine moorland plateau about three miles from Haslemere, with an elevation of 900 feet above the sea, I have recently erected a small iron hut, which forms, not only a place of rest, but an extremely suitable station for meteorological observations. Here, since the beginning of last November, I have continued to record from time to time the temperature of the earth’s surface as compared with that of the air above the surface. My object was to apply, if possible, the results which my experiments had established regarding the action of aqueous vapour upon radiant heat. Two stout poles about 6 feet high were firmly fixed in the earth 8 feet asunder. From one pole to the other was stretched a string, from the centre of which the air thermometer was suspended. Its bulb was 4 feet above the earth. The surface thermometer was placed upon a layer of cotton wool, on a spot cleared of heather, which thickly covered the rest of the ground. The outlook from the thermometers was free and extensive; with the exception of the iron hut just referred to, there was no house near, the hut being about 50 yards distant from the thermometers.

Oscillating Contractions in Protoplasmic Strands of Physarum: Mechanical and Thermal Methods of Phase Shifting for Studying the Nature of the Synchronizing Factor and its Transmission

1980 ◽  
Vol 85 (1) ◽  
pp. 21-31
Author(s):  
U. ACHENBACH ◽  
K. E. WOHLFARTH-BOTTERMANN
Keyword(s):  
Contractile Activity ◽  
Signal Transmission ◽  
Rapid Change ◽  
Isometric Tension ◽  
The Other ◽  
Rapid Phase ◽  
Thermal Methods ◽  
Original Length ◽  
Set Up ◽  
Rhythmic Contractile Activity

A new experimental investigation chamber was used to analyse the control of rhythmic contractile activity in Physarum. A strand was mounted in such a way that isometric tension measurements of contraction forces could be made on two regions independently, the two regions remaining connected. It was possible to disturb one region experimentally and to compare its behaviour with the other. A short time after being set up in the apparatus, the isometric contraction cycles in the two regions became synchronous. Stretching one region by 50% of its original length induced a phase delay relative to the other. A brief unilateral cold shock (Δt = 5舑15 °C) had a similar phase-retarding effect. Synchrony was subsequently reattained, unless the connecting region was cut or, for example, treated with 30 mM benzamide. In approximately 25% of the investigated strands, a rapid change to a higher temperature (Δt = 2舑5 °C) caused the warmed side to be phase-advanced. However, 75% of the strands did not show a phase shift, suggesting that a rapid phase regulation is supported by increased temperature. The described experimental assay is suitable for analysing the pathway and the nature of signal transmission in plasmodial strands. Note: Partly presented at the International Titisee-Conference on Cellular Oscillators, 22舑24 March 1979 (see J. exp. Biol. (1979)).

Thermal Stress and the Contribution of Radiant Heat

1980 ◽  
Vol 66 (1) ◽  
pp. 45-49
Author(s):  
D. J. Smith
Keyword(s):  
Radiant Heat ◽  
The Other ◽  
Endurance Time ◽  
Deep Body Temperature ◽  
Cardiovascular Stress ◽  
Globe Temperature ◽  
Climatic Severity ◽  
The Relationship ◽  
Deep Body ◽  
Different Climates

AbstractSixteen young, healthy volunteers were exposed to eight thermally severe environments, each subject being exposed to four different climates. Four climates had a radiant heat component; globe temperature some 10°C above dry bulb. In the other four climates, the globe temperature was close to the dry bulb. Measurements of endurance time in the different climates were made, as were changes in deep body temperature and heart rate. The relationship between the wet bulb globe thermometer index (WBGT) and stay times in the non-radiant climates agreed well with that of previous workers. Further, the WBGT index appeared adequate, in the situation under study, in terms of its ability to quantify climatic severity, thermal and cardiovascular stress and hence endurance in climates with a high radiant heat component.

scholarly journals Human impacts and their interactions in the Baltic Sea region

2021 ◽  
Author(s):  
Marcus Reckermann ◽  
Anders Omstedt ◽  
Tarmo Soomere ◽  
Juris Aigars ◽  
Naveed Akhtar ◽  
...  
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Human Activities ◽  
Human Impacts ◽  
The Other ◽  
Indigenous Species ◽  
General Description ◽  
The Baltic Sea ◽  
Baltic Sea Region ◽  
The Baltic

Abstract. Coastal environments, in particular heavily populated semi-enclosed marginal seas and coasts like the Baltic Sea region, are stongly affected by human activities. A multitude of human impacts, including climate change, affects the different compartments of the environment, and these effects interact with each other. As part of the Baltic Earth Assessment Reports (BEAR), we present an inventory and discussion of different human-induced factors and processes affecting the environment of the Baltic Sea region, and their interrelations. Some are naturally occurring and modified by human activities (i.e. climate change, coastal processes, hypoxia, acidification, submarine groundwater discharges, marine ecosystems, non-indigenous species, land use and land cover), some are completely human-induced (i.e. agriculture, aquaculture, fisheries, river regulations, offshore wind farms, shipping, chemical contamination, dumped warfare agents, marine litter and microplastics, tourism, coastal management), and they are all interrelated to different degrees. We present a general description and analysis of the state of knowledge on these interrelations. Our main insight is that climate change has an overarching, integrating impact on all of the other factors and can be interpreted as a background effect, which has different implications for the other factors. Impacts on the environment and the human sphere can be roughly allocated to anthropogenic drivers such as food production, energy production, transport, industry and economy. We conclude that a sound management and regulation of human activities must be implemented in order to use and keep the environments and ecosystems of the Baltic Sea region sustainably in a good shape. This must balance the human needs, which exert tremendous pressures on the systems, as humans are the overwhelming driving force for almost all changes we see. The findings from this inventory of available information and analysis of the different factors and their interactions in the Baltic Sea region can largely be transferred to other comparable marginal and coastal seas in the world.

BODY TEMPERATURE AND SURVIVAL OF PREMATURE INFANTS

PEDIATRICS ◽  
1964 ◽  
Vol 34 (2) ◽  
pp. 171-181
Author(s):  
Richard L. Day ◽  
Lawrence Caliguiri ◽  
Carolyn Kamenski ◽  
Florence Ehrlich
Keyword(s):  
Body Temperature ◽  
Premature Infants ◽  
Excess Mortality ◽  
Radiant Heat ◽  
The Other ◽  
Control Group ◽  
Heat Lamp ◽  
Autopsy Data ◽  
Males And Females ◽  
High Risk Infants

One hundred and twenty-five premature infants were divided into two groups, one being treated in incubators at an air temperature of 31.8°C (89°F) and the other in the same style of incubator, but with more careful regulation of body temperature by a radiant heat device actuated by a thermistor taped to the abdomen and set for 36°C (97°F). There was a trend toward lower mortality among the heat lamp babies which was present in males and females, whites and Negroes, and which was not related to an accidental distribution of high risk infants to the control group. The advantage was most pronounced among babies vaginally born in the vertex position between birth weights of 800 and 1,599 gm inclusive. The cause of the excess mortality was not revealed by autopsy data. The results confirm those of Silverman, but extend them in that his "normothermic" babies were in conditions similar to our cold or control babies. The trends shown in this paper, taken in combination with those of the previous studies of Silverman, of Jolly et al., and of Buetow and Klein14 in this issue, point to the desirability of care in the control of the temperature of premature infants.

Software Tools Used in Math Refresher Courses at the University of Alcalá, Spain

2012 ◽  
pp. 327-349
Author(s):  
J.G. Alcázar ◽  
M. Marvá ◽  
D. Orden ◽  
F. San Segundo
Keyword(s):  
Mathematics Education ◽  
The Other ◽  
Sufficient Information ◽  
Software System ◽  
General Description ◽  
Software Suite ◽  
Learning Platform ◽  
E Learning ◽  
The One ◽  
The University

We describe our experience of using the following mathematical tools: an e-learning platform (Moodle), several components of the WIRIS software suite for mathematics education (the formula editor, WIRIS CAS, and WIRIS-Quizzes), the dynamical geometry package GeoGebra, the computational knowledge engine Wolfram Alpha, and the mathematics software system SAGE. Our aim in this chapter is two-fold: on the one hand, we report the use of these tools in Math refresher courses. On the other, we provide sufficient information about them for readers to decide on the usefulness of these tools in their own particular context (maybe different from that of a refresher course). More specifically, for each tool we give a general description, some comments on its use in Math refresher courses, and a list of (general) advantages and drawbacks.

Modelling of Complex DEH Systems

2017 ◽  
Author(s):  
Øyvind Pharo Hanisch
Keyword(s):  
Electric Heating ◽  
The Other ◽  
Flow Assurance ◽  
Complex Field ◽  
Close Interaction ◽  
Close Proximity ◽  
Current Systems

Direct Electric Heating (DEH) is an increasingly attractive method for flow assurance that has been in use for more than 15 years. All current systems in operation consist of a single flowline or have subsea architecture such that interaction between systems as well as components in the proximity is limited. DEH is selected as flow assurance for two ongoing field developments where the layout is such that there will be interaction with other subsea architecture. One system has numerous flowline systems in close interaction and the other has unfavorable crossing. This paper presents some of the design aspects which do arise for fields where the flowlines are in close proximity to each other. The paper also discusses how to handle interference with existing infrastructure when installing DEH in a complex field layout. The aspects studied are effect on power rating, ac corrosion and thermal rating of cables and flowlines.

Compression Stress Strain of Rubber

1933 ◽  
Vol 6 (1) ◽  
pp. 126-150 ◽  
Author(s):  
J. R. Sheppard ◽  
W. J. Clapson
Keyword(s):  
Hollow Sphere ◽  
Compressive Force ◽  
Strain Curve ◽  
The Other ◽  
One Dimension ◽  
Compression Stress ◽  
Stress Strain ◽  
Strain Data ◽  
Tensile Forces ◽  
Strain Axis

Abstract 1. A relation of simple form between compressive force and equivalent two-way tensile forces is developed. 2. Based on this relation, a new method for determining the compression stress strain of rubber is outlined, which avoids difficulties and errors inherent in direct compression. It consists in applying tensile forces simultaneously in two directions, and, from these and the strained dimensions, in computing the compressive force that would have produced the same deformation. 3. The mode of applying the two-way tensiles is to inflate a hollow sphere of rubber; the experimental data required to determine the compression stress strain are pressure of gas in, and dimensions of, the inflating hollow sphere. 4. The method has been applied to cold-cured pure-gum rubber in the form of toy balloons which, in its ordinary elongation stress strain, shows a breaking elongation of about 650 to 700 per cent and a tensile of 30 to 40 kg. per square centimeter. While the numerical values obtained on this stock have no special significance, as they will vary from stock to stock, the following are examples: breaking compression, about 97.3 per cent; breaking compressive force, 6000 to 9000 kg. per square centimeter (on original cross section); hysteresis, 29 to 35 per cent of work of compression to near rupture. 5. As a common measuring stick by which to gage degree of strain in deformations of different types—e. g., increasing one dimension (and diminishing the other two) as against diminishing one dimension (and increasing the other two)—energy seems the best. Energy at break for ordinary elongation stress strain was 50 to 70 kg. cm. per cubic centimeter, and for compression stress strain was 89 to 103 kg. cm. per cubic centimeter. 6. The compression stress-strain data may, if desired, be expressed in terms of two-way tensiles vs. two-way elongations. Energy of compression may be computed either as twice the area subtended between such a curve and the strain axis, or as the area between the compression stress strain and the strain axis. 7. It is strongly indicated that the compression stress strain of rubber is continuous with the ordinary elongation stress strain when both are plotted in the same units, and that the complete stress strain should accordingly be considered as a single continuous curve having an elongation branch and a compression branch with the origin as dividing point. 8. The analytic features of the complete stress strain are described. 9. Granting the observed concavity of the upper part of the elongation stress strain, and the thesis of continuity between elongation and compression, a point of inflection is bound to exist theoretically. 10. Implications of the thesis of continuity are: (1) An equation for the stress-strain curve must fit the complete curve; it is not sufficient that it fit the elongation branch only. (2) It is impossible to compute the compression stress strain from the ordinary (one-way) elongation stress-strain data. The two sets of data are related empirically. 11. When compressive force and equivalent two-way tensiles are based on actual cross sections, stress conditions at a point are expressed and we have the simple rule: Pressure at a point is numerically equal to the transverse tensions which, substituted therefor, will maintain the same strain.

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