Elastic response of (1 − x)Ba(Ti0.8Zr0.2)O3 – x(Ba0.7Ca0.3)TiO3 (x = 0.45–0.55) and the role of the intermediate orthorhombic phase in enhancing the piezoelectric coupling

2014 ◽  
Vol 105 (23) ◽  
pp. 232904 ◽  
Author(s):  
F. Cordero ◽  
F. Craciun ◽  
M. Dinescu ◽  
N. Scarisoreanu ◽  
C. Galassi ◽  
...  
Keyword(s):  
Orthorhombic Phase ◽  
Elastic Response ◽  
Piezoelectric Coupling

Virtual trabecular bone models and their mechanical response

2008 ◽  
Vol 222 (8) ◽  
pp. 1185-1195 ◽  
Author(s):  
F E Donaldson ◽  
P Pankaj ◽  
A H Law ◽  
A H Simpson
Keyword(s):  
Finite Element ◽  
Trabecular Bone ◽  
Mechanical Behaviour ◽  
Mechanical Response ◽  
Elastic Response ◽  
Anatomical Site ◽  
Virtual Samples ◽  
Micro Level ◽  
Architectural Characteristics

The study of the mechanical behaviour of trabecular bone has extensively employed micro-level finite element (μFE) models generated from images of real bone samples. It is now recognized that the key determinants of the mechanical behaviour of bone are related to its micro-architecture. The key indices of micro-architecture, in turn, depend on factors such as age, anatomical site, sex, and degree of osteoporosis. In practice, it is difficult to acquire sufficient samples that encompass these variations. In this preliminary study, a method of generating virtual finite element (FE) samples of trabecular bone is considered. Virtual samples, calibrated to satisfy some of the key micro-architectural characteristics, are generated computationally. The apparent level elastic and post-elastic mechanical behaviour of the generated samples is examined: the elastic mechanical response of these samples is found to compare well with natural trabecular bone studies conducted by previous investigators; the post-elastic response of virtual samples shows that material non-linearities have a much greater effect in comparison with geometrical non-linearity for the bone densities considered. Similar behaviour has been reported by previous studies conducted on real trabecular bone. It is concluded that virtual modelling presents a potentially valuable tool in the study of the mechanical behaviour of trabecular bone and the role of its micro-architecture.

THE ROLE OF OXYGEN IN YBa2Cu3O7−δ

1988 ◽  
Vol 02 (03n04) ◽  
pp. 379-391 ◽  
Author(s):  
JOHN B. GOODENOUGH ◽  
A. MANTHIRAM
Keyword(s):  
Oxygen Atom ◽  
Oxygen Partial Pressure ◽  
Basal Plane ◽  
Redox Reactions ◽  
Orthorhombic Phase ◽  
Near Neighbor ◽  
Oxidation States ◽  
Internal Electric Field ◽  
Phase 3

Five observations concerning the role of oxygen in the high-Tc superconductors YBa 2 Cu 3 O 7−δ are emphasized: (1) An internal electric field parallel to the c-axis constrains the redox reactions associated with the intercalation/disintercalation of oxygen primarily to the [ CuO 3−δ]3− layers located between Ba 2+ layers. (2) Intercalation of O 2− into the tetragonal YBa 2 Cu 3 O 6 phase results in an ordering onto one of the basal-plane axes of the Cu(1) layer, the b-axis of the orthorhombic phase. (3) Ordering between and within b-axis chains gives rise to discrete phases predicted to occur at O 6.875, O 6.75, O 6.5, O 6.25, and O 6.125. (4) An equilibrium oxidation state for the intercalation layer depends not only on the oxygen partial pressure and temperature, but also on the cations of the structure. (5) At higher oxidation states of the intercalation layer, any oxygen atom on the a-axis interacts with a near-neighbor oxygen on the b-axis to trap out holes in a peroxide ion ( O 2)2−.

Molecular Theories of Rubberlike Elasticity and Polymer Viscoelasticity

1972 ◽  
Vol 45 (3) ◽  
pp. 638-666 ◽  
Author(s):  
Mitchel Shen ◽  
William F. Hall ◽  
Roger E. Dewames
Keyword(s):  
Physical Properties ◽  
Configurational Entropy ◽  
Polymer Chains ◽  
Elastic Response ◽  
Linear Polymers ◽  
Polymer Molecules ◽  
Recent Developments ◽  
Conformational Statistics ◽  
Polymer Viscoelasticity

Abstract The foundation for nearly all the molecular theories of the physical properties of polymers was laid in 1934 when Guth and Mark and Kuhn first recognized the role of configurational entropy of polymer chains. By virtue of ability of their segments to rotate with respect to each other along the chain backbone, macromolecules are capable of assuming a myriad of conformations. It is this long, flexible chain nature of polymer molecules that provides us a link in interpreting the macroscopic physical properties in terms of microscopic molecular dynamics. In this review we shall demonstrate the utilization of conformational statistics in the formulation of molecular theories for two important aspects of the mechanical properties of polymers. The first part deals with the equilibrium elastic response of a crosslinked rubberlike network. A simplified derivation will be given on the basis of the entropic approach. Some of the underlying assumptions will then be examined, and the contribution of internal energy to rubber elasticity scrutinized. The second part describes the transient viscoelastic properties of linear polymers in solution and in bulk. Limitations of the model will be assessed and its applications to experimental data explored. It should be pointed out that a number of reviews are available in the literature both for elasticity and viscoelasticity of polymers. The present work is not an exhaustive review of these fields, but rather concentrates on the more recent developments not previously discussed. The emphasis will be placed upon polymers in the bulk state, although solution properties will be mentioned where appropriate.

scholarly journals Discretion of the Monetary Policy: An Exemplification with Bolivia

2019 ◽  
Vol 66 (1) ◽  
pp. 101-115 ◽  
Author(s):  
Roger Alejandro Banegas Rivero ◽  
Marco Alberto Núñez Ramírez ◽  
Sacnicté Valdez del Ríoe
Keyword(s):  
Monetary Policy ◽  
Central Bank ◽  
Interest Rates ◽  
Open Economy ◽  
Generalized Method Of Moments ◽  
Elastic Response ◽  
Output Gap ◽  
Open Market ◽  
Economic Cycle

Abstract In this paper, we evaluate and quantify the role of the discretion of the monetary policy in an open small and open economy (the case of Bolivia). The results suggest that conventional instruments of the Central Bank respond in different ways: interest rates present a sensitive/elastic response to output gap (actual economic cycle) [1.8]; an inelastic mechanism to inflation [0.5]. On the other hand, open market operations in the Central Bank responds elastically to inflation [1.2] and insensible to the output gap. These results are robust to alternative specification utilizing the Generalized Method of moments (GMM), for the quarterly period from 2000(T1)-2015(T4).

The role of elastic, undrained, and drained responses in triggering earthquakes at Monticello Reservoir, South Carolina

1992 ◽  
Vol 82 (4) ◽  
pp. 1867-1888
Author(s):  
Kusala Rajendran ◽  
Pradeep Talwani
Keyword(s):  
South Carolina ◽  
Pore Pressure ◽  
In Situ Stress ◽  
Elastic Response ◽  
Reservoir Induced Seismicity ◽  
Reservoir Impoundment ◽  
Stress Changes ◽  
Individual Contributions ◽  
Monticello Reservoir

Abstract Following reservoir impoundment, stress changes occur due to elastic response and changes in pore pressure due to drained and undrained responses of the substratum. Elastic response may stabilize or destabilize the reservoir environment, depending on the nature of pre-existing stress field. However, the increase in pore pressure always leads to weakening of the rocks, facilitating the onset of seismicity. In most reservoirs, we usually observe the coupled poroelastic effect, and it is usually difficult to isolate individual contributions. Due to the availability of detailed seismicity and geological and in situ stress data at Monticello Reservoir, it was possible to study various factors that control the mechanism of reservoir-induced seismicity. Our results suggest that, during the filling period, the instability resulted from elastic, undrained, and possibly onset of drained response. Subsequently, the seismicity showed a more consistent pattern associated with diffusion of pore pressure.

Elastic response of Carbon Black reinforced polyester based composites using micromechanical models: Role of interphase

2022 ◽  
pp. 239779142110701
Author(s):  
Mehdi Karevan
Keyword(s):  
Carbon Black ◽  
Thermal Studies ◽  
Elastic Response ◽  
Elastic Behavior ◽  
Analytical Prediction ◽  
Morphological Studies ◽  
Micromechanical Models ◽  
The Impact ◽  
Carbon Based

Carbon-based reinforcements have been widely reported in improving mechanical properties of polymers. However, still few studies exist on the incorporation of the interphase as a result of the interfacial interactions into analytical prediction tools. To better understand the effect of interfacial interphase, this study compares and correlates the experimental mechanical response of polyester based composites filled with carbon black (CB) with the elastic behavior obtained from the micromechanical models. Mold cast composites of polyester reinforced with 0 wt%–10 wt% of CB were fabricated. To determine the length of cooperative rearranging region (CRR) as a measure of the interphase, thermal studies focusing on the variations in the specific heat capacity or the relaxation strength of the composites around the glass transition temperature ( Tg) range were performed using a thermodynamical model. Micromechanical models such as the Halpin-Tsai and Tandon-Weng were used to determine the Young’s modulus with respect to the CB wt% and diameter as well as the interphase thickness and modulus. The results exhibited the sensitivity of the models to the existence of the interphase as a secondary mechanism, which was correlated to the cross-link density and interfacial bonding. The impact results showed the decrease in the impact resistance upon the addition of higher filler loadings ascribed to the destroyed bonding at the interface and CBs agglomeration confirmed by morphological studies. The research results can be further utilized in the explanation of the changes in the elastic response of carbon-based reinforced thermosetting composites emphasizing the key role of interphase.

Mobility of alpha-actinin along growing actin filaments might affect the cellular chirality

2021 ◽  
pp. 1-14
Author(s):  
Xi Li ◽  
Bin Chen
Keyword(s):  
Actin Filaments ◽  
Critical Role ◽  
Axial Direction ◽  
Biomechanical Properties ◽  
Model Analysis ◽  
Elastic Response ◽  
Cell Phenotype ◽  
Radial Fiber ◽  
Proper Functions

Abstract Chirality is a widespread feature existing in nature and can be critical in the proper functions of some organisms. In our previous work, a rotational clutch-filament model for a radial fiber was built to reveal the critical role of α-actinin in the cellular chiral swirling. Here we assume two mobility modes of α-actinin along actin filaments. In Mode A, where α-actinin concomitantly moves together with a growing filament, our model analysis suggests that cells cannot swirl clockwise; in Mode B, where α-actinin is fixed along the axial direction of the radial fiber instead, our model analysis suggests that both counter-clockwise and clockwise chiral swirling occur, in consistency with experiments. Thus, our studies suggest that how α-actinin moves along growing filaments within a radial fiber would strongly affect cellular swirling. In addition, the previous rotational clutch-model has been improved by considering the elastic response of a radial fiber to a torque and distributed biomechanical properties of varied cell phenotype.

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