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Search Results: 1 - 10 of 150515 matches for " H. H. Hardy "
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Euler-Lagrange Elasticity: Differential Equations for Elasticity without Stress or Strain  [PDF]
H. H. Hardy
Journal of Applied Mathematics and Physics (JAMP) , 2013, DOI: 10.4236/jamp.2013.17004

Differential equations to describe elasticity are derived without the use of stress or strain. The points within the body are the independent parameters instead of strain and surface forces replace stress tensors. These differential equations are a continuous analytical model that can then be solved using any of the standard techniques of differential equations. Although the equations do not require the definition stress or strain, these quantities can be calculated as dependent parameters. This approach to elasticity is simple, which avoids the need for multiple definitions of stress and strain, and provides a simple experimental procedure to find scalar representations of material properties in terms of the energy of deformation. The derived differential equations describe both infinitesimal and finite deformations.

Euler-Lagrange Elasticity with Dynamics  [PDF]
H. H. Hardy
Journal of Applied Mathematics and Physics (JAMP) , 2014, DOI: 10.4236/jamp.2014.213138
Abstract: The equations of Euler-Lagrange elasticity describe elastic deformations without reference to stress or strain. These equations as previously published are applicable only to quasi-static deformations. This paper extends these equations to include time dependent deformations. To accomplish this, an appropriate Lagrangian is defined and an extrema of the integral of this Lagrangian over the original material volume and time is found. The result is a set of Euler equations for the dynamics of elastic materials without stress or strain, which are appropriate for both finite and infinitesimal deformations of both isotropic and anisotropic materials. Finally, the resulting equations are shown to be no more than Newton's Laws applied to each infinitesimal volume of the material.
Linear Algebra Provides a Basis for Elasticity without Stress or Strain  [PDF]
H. H. Hardy
Soft (Soft) , 2015, DOI: 10.4236/soft.2015.43003
Abstract: Linear algebra provides insights into the description of elasticity without stress or strain. Classical descriptions of elasticity usually begin with defining stress and strain and the constitutive equations of the material that relate these to each other. Elasticity without stress or strain begins with the positions of the points and the energy of deformation. The energy of deformation as a function of the positions of the points within the material provides the material properties for the model. A discrete or continuous model of the deformation can be constructed by minimizing the total energy of deformation. As presented, this approach is limited to hyper-elastic materials, but is appropriate for infinitesimal and finite deformations, isotropic and anisotropic materials, as well as quasi-static and dynamic responses.
Neutrino-electron processes in a strongly magnetized thermal plasma
Stephen J. Hardy,Markus H. Thoma
Physics , 2000, DOI: 10.1103/PhysRevD.63.025014
Abstract: We present a new method of calculating the rate of neutrino-electron interactions in a strong magnetic field based on finite temperature field theory. Using this method, in which the effect of the magnetic field on the electron states is taken into account exactly, we calculate the rates of all of the lowest order neutrino-electron interactions in a plasma. As an example of the use of this technique, we explicitly calculate the rate at which neutrinos and antineutrinos annihilate in a highly magnetized plasma, and compare that to the rate in an unmagnetized plasma. The most important channel for energy deposition is the gyromagnetic absorption of a neutrino-antineutrino pair on an electron or positron in the plasma ($\nu\bar{\nu} e^\pm\leftrightarrow e^\pm$). Our results show that the rate of annihilation increases with the magnetic field strength once it reaches a certain critical value, which is dependent on the incident neutrino energies and the ambient temperature of the plasma. It is also shown that the annihilation rates are strongly dependent on the angle between the incident particles and the direction of the magnetic field. If sufficiently strong fields exist in the regions surrounding the core of a type II supernovae or in the central engines of gamma ray bursts, these processes will lead to more efficient plasma heating mechanism than in an unmagnetized medium, and moreover, one which is intrinsically anisotropic.
Computational ghost imaging versus imaging laser radar for 3D imaging
Nicholas D. Hardy,Jeffrey H. Shapiro
Physics , 2012, DOI: 10.1103/PhysRevA.87.023820
Abstract: Ghost imaging has been receiving increasing interest for possible use as a remote-sensing system. There has been little comparison, however, between ghost imaging and the imaging laser radars with which it would be competing. Toward that end, this paper presents a performance comparison between a pulsed, computational ghost imager and a pulsed, floodlight-illumination imaging laser radar. Both are considered for range-resolving (3D) imaging of a collection of rough-surfaced objects at standoff ranges in the presence of atmospheric turbulence. Their spatial resolutions and signal-to-noise ratios are evaluated as functions of the system parameters, and these results are used to assess each system's performance trade-offs. Scenarios in which a reflective ghost-imaging system has advantages over a laser radar are identified.
Neanderthal Use of Fish, Mammals, Birds, Starchy Plants and Wood 125-250,000 Years Ago
Bruce L. Hardy, Marie-Hélène Moncel
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0023768
Abstract: Neanderthals are most often portrayed as big game hunters who derived the vast majority of their diet from large terrestrial herbivores while birds, fish and plants are seen as relatively unimportant or beyond the capabilities of Neanderthals. Although evidence for exploitation of other resources (small mammals, birds, fish, shellfish, and plants) has been found at certain Neanderthal sites, these are typically dismissed as unusual exceptions. The general view suggests that Neanderthal diet may broaden with time, but that this only occurs sometime after 50,000 years ago. We present evidence, in the form of lithic residue and use-wear analyses, for an example of a broad-based subsistence for Neanderthals at the site of Payre, Ardèche, France (beginning of MIS 5/end of MIS 6 to beginning of MIS 7/end of MIS 8; approximately 125–250,000 years ago). In addition to large terrestrial herbivores, Neanderthals at Payre also exploited starchy plants, birds, and fish. These results demonstrate a varied subsistence already in place with early Neanderthals and suggest that our ideas of Neanderthal subsistence are biased by our dependence on the zooarchaeological record and a deep-seated intellectual emphasis on big game hunting.
Risk assessment of plant protection products
Hardy T,Bopp S,Egsmose M,Fontier H
EFSA Journal , 2012, DOI: 10.2903/j.efsa.2012.s1010
Abstract: EFSA’s Panel on Plant Protection Products and their Residues (PPR Panel) provides independent scientific advice in the field of risk assessment of plant protection products (PPPs, pesticides). Since its establishment in 2003 under Regulation (EC) No 178/2002, it has delivered a series of scientific outputs in support of evaluation of pesticide active substances, establishing scientific principles and guidance documents in the field of pesticide risk assessment and in support of decision making of European Union (EU) law makers. Next to a series of scientific opinions evaluating specific adverse effects of PPPs for human health (like for instance carcinogenicity) the Panel also delivered scientific opinions on general principles in the field of human health risk assessment (like reference value setting) and is, in particular over the last years, very much engaged in development of methodologies to meet new challenges in regulatory risk assessments such as assessment of toxicity of pesticide metabolites and potential cumulative effects of pesticides to human health. Fate, behaviour and transformation of pesticides after their application and consequent release to the environment are a major aspect of pesticide risk assessment. The PPR Panel has achieved major accomplishments by delivering guidance and scientific opinions on degradation in soil, exposure of soil organisms and assessment of environmental risks by use of pesticides in greenhouses or grown under cover. A series of scientific opinions have been delivered also in the field of environmental risk assessment of pesticides. Scientific output covered specific issues arising in the peer review of specific active substances, revision of data requirements, development of risk assessment methodologies and the development of guidance documents. A major milestone of the PPR Panel was the development of the methodological framework for deriving specific protection goals for environmental risk assessment of pesticides in view of the future dialogue between risk managers and risk assessors during the next steps of the revision of the ecotoxicology guidance documents.
Divining Integrative Medicine
Steven H. Stumpf,Simon J. Shapiro,Mary L. Hardy
Evidence-Based Complementary and Alternative Medicine , 2008, DOI: 10.1093/ecam/nem104
Molecular Dynamics Simulations Suggest that Electrostatic Funnel Directs Binding of Tamiflu to Influenza N1 Neuraminidases
Ly Le ?,Eric H. Lee ?,David J. Hardy,Thanh N. Truong,Klaus Schulten
PLOS Computational Biology , 2010, DOI: 10.1371/journal.pcbi.1000939
Abstract: Oseltamivir (Tamiflu) is currently the frontline antiviral drug employed to fight the flu virus in infected individuals by inhibiting neuraminidase, a flu protein responsible for the release of newly synthesized virions. However, oseltamivir resistance has become a critical problem due to rapid mutation of the flu virus. Unfortunately, how mutations actually confer drug resistance is not well understood. In this study, we employ molecular dynamics (MD) and steered molecular dynamics (SMD) simulations, as well as graphics processing unit (GPU)-accelerated electrostatic mapping, to uncover the mechanism behind point mutation induced oseltamivir-resistance in both H5N1 “avian” and H1N1pdm “swine” flu N1-subtype neuraminidases. The simulations reveal an electrostatic binding funnel that plays a key role in directing oseltamivir into and out of its binding site on N1 neuraminidase. The binding pathway for oseltamivir suggests how mutations disrupt drug binding and how new drugs may circumvent the resistance mechanisms.
Scenario Analysis of Nutrient Removal from Municipal Wastewater by Microalgal Biofilms
Nadine C. Boelee,Hardy Temmink,Marcel Janssen,Cees J. N. Buisman,René H. Wijffels
Water , 2012, DOI: 10.3390/w4020460
Abstract: Microalgae can be used for the treatment of municipal wastewater. The application of microalgal biofilms in wastewater treatment systems seems attractive, being able to remove nitrogen, phosphorus and COD from wastewater at a short hydraulic retention time. This study therefore investigates the area requirement, achieved effluent concentrations and biomass production of a hypothetical large-scale microalgal biofilm system treating municipal wastewater. Three scenarios were defined: using microalgal biofilms: (1) as a post-treatment; (2) as a second stage of wastewater treatment, after a first stage in which COD is removed by activated sludge; and (3) in a symbiotic microalgal/heterotrophic system. The analysis showed that in the Netherlands, the area requirements for these three scenarios range from 0.32 to 2.1 m2 per person equivalent. Moreover, it was found that it was not possible to simultaneously remove all nitrogen and phosphorus from the wastewater, because of the nitrogen:phosphorus ratio in the wastewater. Phosphorus was limiting in the post-treatment scenario, while nitrogen was limiting in the two other scenarios. Furthermore, a substantial amount of microalgal biomass was produced, ranging from 13 to 59 g per person equivalent per day. These findings show that microalgal biofilm systems hold large potential as seasonal wastewater treatment systems and that it is worthwhile to investigate these systems further.
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