Memory of Prior Dynamic Strain History in Filled Rubbers

2010 ◽  
Vol 83 (2) ◽  
pp. 149-159 ◽  
Author(s):  
Xiaorong Wang ◽  
Christopher G. Robertson
Keyword(s):  
Small Strain ◽  
Dynamic Strain ◽  
Hole Burning ◽  
Strain History ◽  
Power Relationship ◽  
Filled Elastomers ◽  
Dynamic Spectra ◽  
Filled Rubbers ◽  
Spectrum Hole ◽  
Relationship Of

Abstract We recently discovered that particle-reinforced rubbers after being sheared (or aged) in oscillation at a frequency ƒa at a small strain γa (e.g., ∼1% strain) for time ta can often display a spectrum hole or drop in their dissipation spectra. The location of the hole depends on the aging strain amplitude γa. The depth of this hole is influenced by both the oscillatory aging frequency ƒa and the aging duration ta, and follows a simple power relationship of the product of ƒa and ta. Sequential shear at two strains reveals that when γa1>γa2 the resulting dynamic spectra appear to be a combination of that aged at γa1 and γa2, whereas for γa1>γa2, the resulting dynamic spectra only reflect the characteristic hole burning of the second strain after holding at γa2. This new memory effect occurs at very small strains in filled elastomers and involves material stiffening during the strain aging; both of those features are quite different from the Mullins effect. Also, this new memory is found to last for more than 10 days without any noticeable sign of disappearing.

scholarly journals Non-Monotonic Sensor Behavior of Carbon Particle-Filled Textile Strain Sensors

2021 ◽  
Vol 6 (1) ◽  
pp. 13
Author(s):  
Johannes Mersch ◽  
Henriette Probst ◽  
Andreas Nocke ◽  
Chokri Cherif ◽  
Gerald Gerlach
Keyword(s):  
Thermoplastic Polyurethane ◽  
Carbon Particle ◽  
Equivalent Circuit Model ◽  
Conductive Filler ◽  
Underlying Mechanism ◽  
Human Motion ◽  
Strain Sensors ◽  
Material Behavior ◽  
Strain History ◽  
Filled Elastomers

Carbon particle-filled elastomers are a widely researched option to be used as piezoresistive strain sensors for soft robotics or human motion monitoring. Therefore, various polymers can be compounded with carbon black (CB), carbon nanotubes (CNT) or graphene. However, in many studies, the electrical resistance strain response of the carbon particle-filled elastomers is non-monotonic in dynamic evaluation scenarios. The non-monotonic material behavior is also called shoulder phenomenon or secondary peak. Until today, the underlying cause is not sufficiently well understood. In this study, several influencing test parameters on the shoulder phenomena are explored, such as strain level, strain rate and strain history. Moreover, material parameters such as CNT content and anisotropy are varied in melt-spun CNT filled thermoplastic polyurethane (TPU) filament yarns, and their non-monotonic sensor response is evaluated. Additionally, a theoretical concept for the underlying mechanism and thereupon-based model is presented. An equivalent circuit model is used, which incorporates the visco-elastic properties and the characteristic of the percolation network formed by the conductive filler material. The simulation results are in good agreement when compared to the experimental results.

Power outputs of slow and fast skeletal muscles of mice

1990 ◽  
Vol 68 (3) ◽  
pp. 1282-1285 ◽  
Author(s):  
S. V. Brooks ◽  
J. A. Faulkner ◽  
D. A. McCubbrey
Keyword(s):  
Direct Consequence ◽  
Stimulation Frequency ◽  
Maximum Power ◽  
Power Relationships ◽  
Power Relationship ◽  
Shortening Velocity ◽  
Optimum Velocity ◽  
Power Outputs ◽  
Relationship Of ◽  
Frequency Power

The purpose of this study was to contrast the frequency-power relationship of slow soleus and fast extensor digitorum longus (EDL) muscles to their frequency-force relationships and to investigate factors involved in the development of maximum power during a single contraction. Stimulation frequency-force and stimulation frequency-power relationships were determined for soleus and EDL muscles of the mouse for single contractions in situ at 35 degrees C. Power was measured during isovelocity shortening contractions with displacement through 10% of fiber length at the optimum velocity. Optimum velocity was defined as the shortening velocity for the generation of maximum power for a given stimulation frequency. Both force (N/cm2) and power (watts/kg) increased with stimulation frequency until a plateau was reached. For the frequency-force relationship, the curve for soleus muscles was merely shifted to the left of that for EDL muscles. In contrast, the power developed by EDL muscles was greater than that of soleus muscles (P less than 0.05) at each stimulation frequency. The higher power was a direct consequence of higher optimum velocities for EDL muscles compared with soleus muscles.

Laser-Doppler assessment of brain microcirculation: effect of systemic alterations

1989 ◽  
Vol 256 (4) ◽  
pp. H1247-H1254 ◽  
Author(s):  
R. L. Haberl ◽  
M. L. Heizer ◽  
A. Marmarou ◽  
E. F. Ellis
Keyword(s):  
Blood Flow ◽  
Blood Perfusion ◽  
Laser Doppler ◽  
Power Relationship ◽  
Arterial Pco2 ◽  
Cranial Window ◽  
Cell Velocity ◽  
Clearance Flow ◽  
Pial Arterioles ◽  
Relationship Of

There is a need for new technical approaches whereby the cerebral microcirculation can be easily and continuously assessed. The objective of this study was to determine whether laser-Doppler (LD) flowmetry can be utilized to assess changes in cerebral cortical blood flow and to determine whether changes in blood perfusion measured by LD flowmetry correlate with simultaneously measured changes in flow measured by H2 clearance in cats or with changes in pial arteriolar diameter measured with a microscope in rabbits equipped with a closed cranial window. In the rabbit experiments a 0.84-mm-diam LD probe was inserted through a cranial window port, and in the cat experiments the probe was fixed adjacent to the H2 probe. The probe was fixed at a distance of 1-2 mm from the cortical surface, where it and its associated electronics detect changes in blood cell velocity and blood volume within a tissue volume of approximately 1 mm3. Volume and velocity are multiplied to provide a flow signal. When cerebral blood flow in cats was decreased by hyperventilation-induced hypocapnia and increased by norepinephrine-induced hypertension, the percent changes in LD flow and H2 clearance flow changed linearly (r = 0.94, slope = 0.97). When arterial PCO2 was increased from 28 to 48 mmHg in the rabbit experiments, the pial arterioles dilated 19 +/- 4% (mean +/- SE) and LD flow increased by 74 +/- 9%, LD flow changes which would be predicted by a third power relationship of diameter to flow.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Reporting controversy in health policy: A content and field analysis

2009 ◽  
Vol 15 (2) ◽  
pp. 35-53 ◽  
Author(s):  
Chris Nash
Keyword(s):  
Field Analysis ◽  
Power Relationship ◽  
Negative Attitudes ◽  
Editorial Policies ◽  
News Reporting ◽  
Reporting Practices ◽  
Journalism Studies ◽  
Daily Telegraph ◽  
Relationship Of ◽  
General Community

This article reports on the research and analysis of editorial attitudes and news reporting in two prominent Sydney newspapers—The Daily Telegraph (DT) and The Sydney Morning Herald (SMH)—about the establishment and operation of the Medically Supervised Injecting Room (MSIC) in Kings Cross from January 1999 to December 2006. The establishment of the MSIC was highly controversial and generated strongly partisan attitudes among politicians, experts, local businesses and the general community. The research compares the editorial stance of these newspapers towards the injecting room and the reporting practices of the newspapers, in particular the range of sources used by the journalists; it deploys a content analysis to identify positive and negative attitudes in the preferred readings of the texts, the usage of sources within the reports and the partisan affiliations of those sources. It reveals stark differences in the reporting of the controversy by the two newspapers, and that the reporting differences were aligned with the respective editorial policies of the mastheads. The interpretation of these empirical findings using field theory is located within the debates in the journalism studies literature about the power relationship of journalistic practices to the interests of sources.

Philip Roth’s Kinds of Writing

2015 ◽  
Author(s):  
Bharat Tandon
Keyword(s):  
Nineteenth Century ◽  
Twentieth Century ◽  
Social Indicators ◽  
Power Relationship ◽  
Philip Roth ◽  
New Yorker ◽  
Times Square ◽  
The 1950S ◽  
Relationship Of ◽  
Implicit Power

This chapter explores The New Yorker's distinctive relationship with the Manhattan cityscape within which it was conceived and produced. It suggests ways in which both the magazine's treatments of the value of readable social indicators, and the larger cultural cachet of the magazine itself in the 1950s and 1960s, offered the young Philip Roth an early engagement with ideas that were to become defining imaginative preoccupations across his fictional and critical oeuvre, from Goodbye, Columbus to Nemesis. The chapter shows how there remains an important difference between textual cityscapes and Times Square in the middle of the twentieth century. Reading a nineteenth-century poster or a handbill may have been fascinating or disorientating to a passerby, but for the most part, the implicit power relationship of conventional reading would not have been challenged.

“For a Few Senators More”? Negotiating Constitutional Changes During Chile's Transition To Democracy

2005 ◽  
Vol 47 (02) ◽  
pp. 51-75
Author(s):  
Fredrik Uggla
Keyword(s):  
Contextual Factors ◽  
Transition To Democracy ◽  
Military Regime ◽  
Final Outcome ◽  
The Political ◽  
Power Relationship ◽  
Theoretical Perspectives ◽  
Relations Of Power ◽  
Relationship Of ◽  
Constitutional Changes

Abstract Chile's 1980 Constitution embodied the political aspirations of the nation's military regime. Before democratization, the constitution underwent a process of reform that did away with some of its most blatantly authoritarian provisions but preserved a set of institutions that would characterize and constrain the regained Chilean democracy. This article presents an account of that process. It juxtaposes two theoretical perspectives: one that sees the results as determined primarily by the power relationship of the participants, and one that stresses contextual factors, such as institutional traditions. This study argues that while the Chilean case largely confirms the importance of the existing constitution for the outcome, the final outcome depended nonetheless on the participants' assessment of the relations of power, and therefore might have been open to different results.

Measurement of Ethical Values

1973 ◽  
Vol 36 (3_suppl) ◽  
pp. 1075-1088E
Author(s):  
Joseph H. Jackson
Keyword(s):  
College Students ◽  
Power Relationship ◽  
Ethical Values ◽  
Student Groups ◽  
Large Numbers ◽  
Fundamental Scale ◽  
Derivative Method ◽  
Relationship Of ◽  
The Relationship

The judgments of the magnitudes of goodness or badness (ethical values) of their successive situations over several days were recorded by three groups of college students. The relationship of their judged magnitudes of goodness and badness to the reported durations of their situations is described here. Judgments in terms of named and briefly described category scales of goodness and badness (given to the students) and judgments in terms of numerical scales (selected within limits by students) displayed the same power relationship between the average durations of the situations and the judged magnitude intervals of ethical value. This relationship held for large numbers of judgments of an individual as well as for the three student groups. It is suggested that this relationship offers a derivative method for measurement of ethical values, relating the category or numerical scales used to the fundamental scale of duration. The relationship also supports the operational definitions of “a good situation” as “a situation in which we act so as to continue the situation as long as we can or as long as it will, and tend to repeat it,” and “a bad situation” as “a situation in which we act so as to discontinue the situation as soon as we can or as soon as it will, and tend not to repeat it.”

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