Science.gov

Sample records for damage evolution law

  1. Characterization of damage evolution in non linear media by means of power law exponent: Modeling and experiments

    NASA Astrophysics Data System (ADS)

    Idjimarene, S.; Scalerandi, M.; Bentahar, M.

    2014-02-01

    Non linear Mesoscopic Elastic materials are characterized by the presence of a distribution of microscopic features like grain boundaries, phase transition and micro-cracks which result in a heterogeneous structure at the mesoscopic scale. It comes out from experimental observations that these materials are described by a non classical nonlinear Equation Of State (EOS) which has the particularity of being multivalued (presents hysteresis in the quasi static stress-strain relation) and amplitude dependent (due to nonlinearity in dynamic experiments). To evaluate the material's integrity, one needs to learn about microscopic defects which are at the origin of fracture process in materials. Thus non linear indicators y could be extracted from quantification of the amplitude dependence of non linear phenomena where power laws y = axb are found to be well fitting this kind of behavior. Several experiments on damage evolution show a wide range of variation of the exponent b of the power law going from 1 up to 3 when y is defined as a dimensionless quantity. Using multi-scale multi-state models to describe microscopic mechanisms expected to take place in such systems, we aim to link the variations of b to the micro-structure, that is to say, to the involved mechanism.

  2. One damage law for different mechanisms

    NASA Astrophysics Data System (ADS)

    Lemaitre, J.; Sermage, J. P.

    1997-07-01

    We consider here a general three-dimensional kinetic damage law. It uses the thermodynamic of irreversible processes formalism and the phenomenological aspects of isotropic damage. It gives the damage rate as a function of its associated variable, the strain energy density release rate and the accumulated plastic strain rate. Associated with different plastic constitutive equations, this damage law takes into account brittle damage, ductile damage, low and high cycle fatigue and creep damage. In this paper we mainly focus on creep-fatigue interaction and high cycle fatigue. Associated to a viscoplastic constitutive equation having kinematic hardening, the damage law gives the non linear creep-fatigue interaction. The agreement with experiments is good. Associated to plastic constitutive equations also having kinematic hardening but introduced in a micromechanical two scale model based on the self-consistent scheme, it models the non linear accumulation of damage induced by a succession of sequences of different amplitudes as well as the effect of the mean stress and the influence of non proportional loading.

  3. Evolution of the Second Law of Thermodynamics

    ERIC Educational Resources Information Center

    Raman, V. V.

    1970-01-01

    Presents the history surrounding the evolution of the second law of thermodynamics. Discusses Sadi Carnot's contributions, but also refers to those by Clapeyron, Thomson, Joule, Clausius, and Boltzman among others. (RR)

  4. Radiation damage evolution in ceramics

    SciTech Connect

    Devanathan, Ramaswami

    2009-09-15

    A review is presented of recent results on radiation damage production, defect accumulation and dynamic annealing in a number of ceramics, such as silicon carbide, zircon and zirconia. Under energetic particle irradiation, ceramics can undergo amorphization by the accumulation of point defects and defect clusters (silicon carbide) or direct impact amorphization (zircon). Ceramics that resist radiation-induced amorphization have mechanisms to dissipate the primary knock-on atom energy, such as replacement collision sequences that leave the lattice undisturbed and low-energy cation site exchange. The presence of engineered mobile defects, such as structural vacancies in stabilized zirconia, can dynamically anneal radiation damage. Thus, defect engineering is a promising strategy to design radiation tolerance for applications such as nuclear waste disposal.

  5. Complexity, organization, evolution, and constructal law

    NASA Astrophysics Data System (ADS)

    Bejan, A.; Errera, M. R.

    2016-02-01

    Physics is concise, simple, unambiguous, and constantly improving. Yet, confusion reigns in the field especially with respect to complexity and the second law of thermodynamics. In this paper, we step back and take a look at these notions—their meaning and definition—on the background provided by nature and thermodynamics. We review the central concepts and words that underpin the physics of evolutionary design today: information, knowledge, evolution, change, arrow of time, pattern, organization, drawings, complexity, fractal dimension, object, icon, model, empiricism, theory, disorder, second law, the "any" system in thermodynamics, morphing freely, and the constructal law. We show, for example, that information is not knowledge, fractal dimension is not a measure of complexity, and pattern is not a live flow architecture. Drawings, as physical means to facilitate the flow of knowledge, are subject to the natural tendency toward design evolution. Complexity, organization, and evolution in nature are most powerful and useful when pursued as a discipline, with precise terms, rules, and principles.

  6. Stochastic damage evolution in textile laminates

    NASA Technical Reports Server (NTRS)

    Dzenis, Yuris A.; Bogdanovich, Alexander E.; Pastore, Christopher M.

    1993-01-01

    A probabilistic model utilizing random material characteristics to predict damage evolution in textile laminates is presented. Model is based on a division of each ply into two sublaminas consisting of cells. The probability of cell failure is calculated using stochastic function theory and maximal strain failure criterion. Three modes of failure, i.e. fiber breakage, matrix failure in transverse direction, as well as matrix or interface shear cracking, are taken into account. Computed failure probabilities are utilized in reducing cell stiffness based on the mesovolume concept. A numerical algorithm is developed predicting the damage evolution and deformation history of textile laminates. Effect of scatter of fiber orientation on cell properties is discussed. Weave influence on damage accumulation is illustrated with the help of an example of a Kevlar/epoxy laminate.

  7. Fatigue damage evolution in uni-directional metal matrix composites using a micro-mechanical damage model

    SciTech Connect

    Echle, R.; Voyiadjis, G.Z.

    1997-07-01

    In recent years Metal Matrix Composites (MMC) have drawn wide attention as candidate materials for high temperature applications needed in aerospace and aeronautic industries. Especially the Titanium Matrix Composites (TMC) have been favored for such applications mainly due to their high strength to weight ratio and their ability to maintain their structural integrity even at elevated temperatures. Despite the increased use of these TMC`s for the last decade there is still a need for appropriate material models able to simulate the material behavior of such advanced MMC`s under severe loading conditions such as fatigue loading. Modeling fatigue behavior of MMC`s requires the prediction of material degradation during the material lifetime through the concept of damage and damage evolution. A micro-mechanical fatigue damage model is proposed here capable of modeling damage evolution at the constituent level. Damage criteria are defined for each individual constituent and appropriate damage evolution laws are derived. Furthermore damage evolution in the interface region is considered separately. The overall composite damage is obtained through the employment of a homogenization procedure such as the Mori-Tanaka averaging scheme. Numerical results are shown for high cycle fatigue with respect to a variation in various material and damage model parameters. Furthermore the damage evolution in the fiber, the matrix and the overall composite is presented for a complete fatigue simulation.

  8. Brittleness Effect on Rock Fatigue Damage Evolution

    NASA Astrophysics Data System (ADS)

    Nejati, Hamid Reza; Ghazvinian, Abdolhadi

    2014-09-01

    The damage evolution mechanism of rocks is one of the most important aspects in studying of rock fatigue behavior. Fatigue damage evolution of three rock types (onyx marble, sandstone and soft limestone) with different brittleness were considered in the present study. Intensive experimental tests were conducted on the chosen rock samples and acoustic emission (AE) sensors were used in some of them to monitor the fracturing process. Experimental tests indicated that brittleness strongly influences damage evolution of rocks in the course of static and dynamic loading. AE monitoring revealed that micro-crack density induced by the applied loads during different stages of the failure processes increases as rock brittleness increases. Also, results of fatigue tests on the three rock types indicated that the rock with the most induced micro-cracks during loading cycles has the least fatigue life. Furthermore, the condition of failure surfaces of the studied rocks samples, subjected to dynamic and static loading, were evaluated and it was concluded that the roughness of failure surfaces is influenced by loading types and rock brittleness. Dynamic failure surfaces were rougher than static ones and low brittle rock demonstrate a smoother failure surface compared to high brittle rock.

  9. Damages for pain and suffering in tort law.

    PubMed

    Mendelson, Danuta

    2008-05-01

    Legislation enacted between 2002 and 2005 by each Australian State and Territory reformed and partially codified the common law of personal injuries. This column examines the nature and history of damages for pain and suffering and analyses the approach taken by different Australian jurisdictions to compensation for non-economic loss. Non-economic loss is generally composed of pain and suffering, loss of amenities of life, and loss of enjoyment of life (some jurisdictions, eg New South Wales, also include disfigurement, and loss of expectation of life). Several jurisdictions have imposed thresholds that a claimant must meet as a prerequisite to suing for damages at common law. PMID:18575167

  10. Entropy evolution law in a laser process

    SciTech Connect

    Chen, Jun-hua Fan, Hong-yi

    2013-07-15

    For the first time, we obtain the entropy variation law in a laser process after finding the Kraus operator of the master equation describing the laser process with the use of the entangled state representation. The behavior of entropy is determined by the competition of the gain and damping in the laser process. The evolution formula for the number of photons is also obtained. -- Highlights: •We apply the thermo-field dynamics method to the master equation of a laser. •We find the operator-sum (Kraus) representation for the density operator. •We find both the normally ordered and compact forms of ρ(t) for ρ{sub 0}=|z〉〈z|. •We find the exact expression of the laser’s entropy. •Our results reveal quantitatively how a laser beam can be generated in a laser.

  11. Fracture and damage evolution of fluorinated polymers

    SciTech Connect

    Brown, E. N.; Rae, P.; Orler, E. B.; Thissell, W. R.; Dattelbaum, D. M.

    2004-01-01

    Fluoropolymers are often semi-crystalline in nature, with their linear chains forming complicated phases near room temperature and ambient pressure. The most widely used fluorocarbon polymer for engineering applications is polytetrafluoroethylene (PTFE), due to its extremely low coefficient of friction, outstanding resistance to corrosion, and excellent electrical properties. The phase structure of PTFE is complex with four well-characterized crystalline phases (three observed at atmospheric pressure) and substantial molecular motion well below the melting point. The first-order transition at 19 C between phases II and IV is an unraveling in the helical conformation. Further rotational disordering and untwisting of the helices occurs above 30 C giving way to phase I. The mechanical behavior, including fracture and damage evolution, of PTFE depends on the chain and segment motions dictated by crystalline phase microstructure. The presence of three unique phases at ambient pressure near room temperature implies that failure during standard operating conditions may be strongly dependent on the phase. This paper presents a preliminary study of fracture and damage evolution in PTFE with the effects of temperature-induced phase on fracture mechanisms. The quasi-static fracture of PTFE in the atmospheric pressure regime, over a range of temperatures, was found to be strongly phase dependent: phase II exhibits brittle-fracture, phase IV displays ductile-fracture with crazing and some stable crack growth, and plastic flow dominates phase 1. The bulk failure properties are correlated to failure mechanisms through fractography of the fracture surfaces (optical microscopy and scanning electron microscopy (SEM)).

  12. A continuum theory of grain size evolution and damage

    NASA Astrophysics Data System (ADS)

    Ricard, Y.; Bercovici, D.

    2009-01-01

    Lithospheric shear localization, as occurs in the formation of tectonic plate boundaries, is often associated with diminished grain size (e.g., mylonites). Grain size reduction is typically attributed to dynamic recrystallization; however, theoretical models of shear localization arising from this hypothesis are problematic because (1) they require the simultaneous action of two creep mechanisms (diffusion and dislocation creep) that occur in different deformation regimes (i.e., in grain size stress space) and (2) the grain growth ("healing") laws employed by these models are derived from normal grain growth or coarsening theory, which are valid in the absence of deformation, although the shear localization setting itself requires deformation. Here we present a new first principles grained-continuum theory, which accounts for both coarsening and damage-induced grain size reduction in a monomineralic assemblage undergoing irrecoverable deformation. Damage per se is the generic process for generation of microcracks, defects, dislocations (including recrystallization), subgrains, nuclei, and cataclastic breakdown of grains. The theory contains coupled macroscopic continuum mechanical and grain-scale statistical components. The continuum level of the theory considers standard mass, momentum, and energy conservation, as well as entropy production, on a statistically averaged grained continuum. The grain-scale element of the theory describes both the evolution of the grain size distribution and mechanisms for both continuous grain growth and discontinuous grain fracture and coalescence. The continuous and discontinuous processes of grain size variation are prescribed by nonequilibrium thermodynamics (in particular, the treatment of entropy production provides the phenomenological laws for grain growth and reduction); grain size evolution thus incorporates the free energy differences between grains, including both grain boundary surface energy (which controls coarsening) and the contribution of deformational work to these free energies (which controls damage). In the absence of deformation, only two mechanisms that increase the average grain size are allowed by the second law of thermodynamics. One mechanism, involving continuous diffusive mass transport from small to large grains, captures the essential components of normal grain growth theories of Lifshitz-Slyosov and Hillert. The second mechanism involves the aggregation of grains and is described using a Smoluchovski formalism. With the inclusion of deformational work and damage, the theory predicts two mechanisms for which the thermodynamic requirement of entropy positivity always forces large grains to shrink and small ones to grow. The first such damage-driven mechanism involving continuous mass transfer from large to small grains tends to homogenize the distribution of grain size toward its initial mean grain size. The second damage mechanism favors the creation of small grains by discontinuous division of larger grains and reduces the mean grain size with time. When considered separately, most of these mechanisms allow for self-similar grain size distributions whose scales (i.e., statistical moments such as the mean, variance, and skewness) can all be described by a single grain scale, such as the mean or maximum. However, the combination of mechanisms, e.g., one that captures the competition between continuous coarsening and mean grain size reduction by breakage, does not generally permit a self-similar solution for the grain size distribution, which contradicts the classic assumption that grain growth laws allowing for both coarsening and recrystallization can be treated with a single grain scale such as the mean size.

  13. Evolution equations: Frobenius integrability, conservation laws and travelling waves

    NASA Astrophysics Data System (ADS)

    Prince, Geoff; Tehseen, Naghmana

    2015-10-01

    We give new results concerning the Frobenius integrability and solution of evolution equations admitting travelling wave solutions. In particular, we give a powerful result which explains the extraordinary integrability of some of these equations. We also discuss ‘local’ conservations laws for evolution equations in general and demonstrate all the results for the Korteweg-de Vries equation.

  14. The evolution of law in biopreparedness.

    PubMed

    Hodge, James G

    2012-03-01

    The decade following the terrorist attacks on September 11, 2001, and ensuing anthrax exposures that same fall has seen significant legal reforms designed to improve biopreparedness nationally. Over the past 10 years, a transformative series of legal changes have effectively (1) rebuilt components of federal, state, and local governments to improve response efforts; (2) created an entire new legal classification known as "public health emergencies"; and (3) overhauled existing legal norms defining the roles and responsibilities of public and private actors in emergency response efforts. The back story as to how law plays an essential role in facilitating biopreparedness, however, is pocked with controversies and conflicts between law- and policymakers, public health officials, emergency managers, civil libertarians, scholars, and others. Significant legal challenges for the next decade remain. Issues related to interjurisdictional coordination; duplicative legal declarations of emergency, disaster, and public health emergency; real-time legal decision making; and liability protections for emergency responders and entities remain unresolved. This article explores the evolving tale underlying the rise and prominence of law as a pivotal tool in national biopreparedness and response efforts in the interests of preventing excess morbidity and mortality during public health emergencies. PMID:22455677

  15. 32 CFR 536.50 - Determination of damages-applicable law.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... September 1, 1995. See Moragne v. States Marine Lines, Inc., 398 U.S. 375 (1970) and federal case law. Where... 32 National Defense 3 2010-07-01 2010-07-01 true Determination of damages-applicable law. 536.50... damages—applicable law. (a) The Federal Tort Claims Act. The whole law of the place where the...

  16. Imaging damage evolution in a small particle metal matrix composite

    PubMed

    Evans; Phaneuf; Boyd

    1999-11-01

    It is difficult to study effectively microstructural damage in metal matrix composites (MMCs) due to artefacts arising from traditional metallographic sample preparation techniques. The sectioning and imaging capabilities of the focused ion beam (FIB) microscope provide an excellent method for studying damage accumulation in MMCs. The capabilities of the FIB system have been used to carry out a study of damage evolution in a powder-processed/hot-extruded Al2080/SiCp MMC. Microvoid damage is found to be preserved accurately during FIB sectioning, allowing measurements of the fraction of decohered particles and the void area fraction. These microscopic damage measurements are correlated with the macroscopic damage parameter, D, as determined by density measurements. Using transmission electron microscopy, the evolution of dislocation structures at the SiC-matrix interfaces has been examined. A previously unreported decohesion mechanism has been observed. PMID:10540267

  17. Evolution of power law distributions in science and society

    NASA Astrophysics Data System (ADS)

    Jeon, Young-Pyo; McCoy, Benjamin J.

    2005-09-01

    Power law distributions have been observed in numerous physical and social systems; for example, the size distributions of particles, aerosols, corporations, and cities are often power laws. Each system is an ensemble of clusters, comprising units that combine with or dissociate from the cluster. Constructing models and investigating their properties are needed to understand how such clusters evolve. To describe the growth of clusters, we hypothesize that a distribution obeys a governing population dynamics equation based on a reversible association-dissociation process. The rate coefficients are considered to depend on the cluster size as power expressions, thus providing an explanation for the asymptotic evolution of power law distributions.

  18. The constructal law and the evolution of design in nature

    NASA Astrophysics Data System (ADS)

    Bejan, Adrian; Lorente, Sylvie

    2011-10-01

    The constructal law accounts for the universal phenomenon of generation and evolution of design (configuration, shape, structure, pattern, rhythm). This phenomenon is observed across the board, in animate, inanimate and human systems. The constructal law states the time direction of the evolutionary design phenomenon. It defines the concept of design evolution in physics. Along with the first and second law, the constructal law elevates thermodynamics to a science of systems with configuration. In this article we review the more recent work of our group, with emphasis on the advances made with the constructal law in the natural sciences. Highlighted are the oneness of animate and inanimate designs, the origin of finite-size organs on animals and vehicles, the flow of stresses as the generator of design in solid structures (skeletons, vegetation), the universality and rigidity of hierarchy in all flow systems, and the global design of human flows. Noteworthy is the tapestry of distributed energy systems, which balances nodes of production with networks of distribution on the landscape, and serves as key to energy sustainability and empowerment. At the global level, the constructal law accounts for the geography and design of human movement, wealth and communications.

  19. Exact Conservation Laws and Exclusion Principle of Biological Evolution

    NASA Astrophysics Data System (ADS)

    Azbel', Mark Ya.

    2003-03-01

    Biological evolution is dynamics of diversity and complexity of living beings from cells to humans. Metabolism, which allows for entropy decrease, and mortality, which allows for natural selection, are its biological must. Their characteristics are known to yield approximate (and rather noisy) universal relations. I conjecture they are accurate for certain ("canonic") fractions of these characteristics. (The conjecture is verified with experimental tests of its counterintuitive predictions). A relation, which is conserved under (invariant to) transformations from one species in its living conditions to another, is a conservation law of biological evolution. Of course, all parameters of such transformations can hardly be comprehensively specified. However, when canonic fractions are additive, the very invariance of the law to an extraordinary wide class of transformations, with no other experimental data, in any given interval of canonic fraction values accurately predicts [1]: either their conservation law is linear, or the population is homogeneous with respect to their values (an "exclusion principle" of their heterogeneity in an otherwise heterogeneous population). To be specific. Metabolism conservation laws (e.g., the dependence of oxygen consumption at rest per heartbeat on the animal mass) are linear. They imply [2] the existence of fundamental biological constants, which are similar to those crucial in physics. Survivability conservation law (the relation between the probabilities to survive to any two given ages) is piecewise linear (with four linear intervals). At the intersections mortality is homogeneous, and its susceptibility to living conditions vanishes. The law predicts that a dominant canonic fraction of mortality in protected populations is reversible for species as different as humans and flies, and may be eliminated. All these predictions agree with experimental data. (For instance, mortality of Swedish females, born in 1916, at 48 years decreases to its value 28 years earlier). The law implies the existence of a new, reversible, kind of evolution, whose relaxation (i.e. adjustment to external conditions) time is small compared to the lifespan of an animal. The law suggests its universal mechanism which may be rapidly and biologically non-specifically regulated, and whose molecular nature may be established in specified physical and biological experiments. A crucial problem is to unravel a complete set of conservation laws of unique evolutionary dynamics and their physiological and physical nature. . [1] M.Ya. Azbel',Phys. Rev. E66, 016107 (2002), Exp. Geront. 37, 859 (2002); [2] M. Ya. Azbel', PNAS USA 91, 12453 (1994)

  20. Law of genome evolution direction: Coding information quantity grows

    NASA Astrophysics Data System (ADS)

    Luo, Liao-Fu

    2009-06-01

    The problem of the directionality of genome evolution is studied. Based on the analysis of C-value paradox and the evolution of genome size, we propose that the function-coding information quantity of a genome always grows in the course of evolution through sequence duplication, expansion of code, and gene transfer from outside. The function-coding information quantity of a genome consists of two parts, p-coding information quantity that encodes functional protein and n-coding information quantity that encodes other functional elements. The evidences on the law of the evolutionary directionality are indicated. The needs of function are the motive force for the expansion of coding information quantity, and the information quantity expansion is the way to make functional innovation and extension for a species. Therefore, the increase of coding information quantity of a genome is a measure of the acquired new function, and it determines the directionality of genome evolution.

  1. Permeability of WIPP Salt During Damage Evolution and Healing

    SciTech Connect

    BODNER,SOL R.; CHAN,KWAI S.; MUNSON,DARRELL E.

    1999-12-03

    The presence of damage in the form of microcracks can increase the permeability of salt. In this paper, an analytical formulation of the permeability of damaged rock salt is presented for both initially intact and porous conditions. The analysis shows that permeability is related to the connected (i.e., gas accessible) volumetric strain and porosity according to two different power-laws, which may be summed to give the overall behavior of a porous salt with damage. This relationship was incorporated into a constitutive model, known as the Multimechanism Deformation Coupled Fracture (MDCF) model, which has been formulated to describe the inelastic flow behavior of rock salt due to coupled creep, damage, and healing. The extended model was used to calculate the permeability of rock salt from the Waste Isolation Pilot Plant (WIPP) site under conditions where damage evolved with stress over a time period. Permeability changes resulting from both damage development under deviatoric stresses and damage healing under hydrostatic pressures were considered. The calculated results were compared against experimental data from the literature, which indicated that permeability in damaged intact WIPP salt depends on the magnitude of the gas accessible volumetric strain and not on the total volumetric strain. Consequently, the permeability of WIPP salt is significantly affected by the kinetics of crack closure, but shows little dependence on the kinetics of crack removal by sintering.

  2. The constructal law of design and evolution in nature

    PubMed Central

    Bejan, Adrian; Lorente, Sylvie

    2010-01-01

    Constructal theory is the view that (i) the generation of images of design (pattern, rhythm) in nature is a phenomenon of physics and (ii) this phenomenon is covered by a principle (the constructal law): ‘for a finite-size flow system to persist in time (to live) it must evolve such that it provides greater and greater access to the currents that flow through it’. This law is about the necessity of design to occur, and about the time direction of the phenomenon: the tape of the design evolution ‘movie’ runs such that existing configurations are replaced by globally easier flowing configurations. The constructal law has two useful sides: the prediction of natural phenomena and the strategic engineering of novel architectures, based on the constructal law, i.e. not by mimicking nature. We show that the emergence of scaling laws in inanimate (geophysical) flow systems is the same phenomenon as the emergence of allometric laws in animate (biological) flow systems. Examples are lung design, animal locomotion, vegetation, river basins, turbulent flow structure, self-lubrication and natural multi-scale porous media. This article outlines the place of the constructal law as a self-standing law in physics, which covers all the ad hoc (and contradictory) statements of optimality such as minimum entropy generation, maximum entropy generation, minimum flow resistance, maximum flow resistance, minimum time, minimum weight, uniform maximum stresses and characteristic organ sizes. Nature is configured to flow and move as a conglomerate of ‘engine and brake’ designs. PMID:20368252

  3. Evolution of the violin: The law of effect in action.

    PubMed

    Wasserman, Edward A; Cullen, Patrick

    2016-01-01

    As is true for most other human inventions, the origin of the violin is unknown. What is known is that this popular and versatile instrument has notably changed over the course of several hundred years. At issue is whether those evolutionary changes in the construction of the violin are the result of premeditated, intelligent design or whether they arose through a trial-and-error process. Recent scientific evidence favors the latter account. Our perspective piece puts these recent empirical findings into a comprehensive selectionist framework. According to this view, the many things we do and make--like violins--arise from a process of variation and selection which accords with the law of effect. Contrary to popular opinion, there is neither mystique nor romance in this process; it is as fundamental and ubiquitous as the law of natural selection. As with the law of natural selection in the evolution of organisms, there is staunch resistance to the role of the law of effect in the evolution of human inventions. We conclude our piece by considering several objections to our perspective. PMID:26569015

  4. 32 CFR 536.50 - Determination of damages-applicable law.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 3 2013-07-01 2013-07-01 false Determination of damages-applicable law. 536.50 Section 536.50 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY CLAIMS AND ACCOUNTS CLAIMS AGAINST THE UNITED STATES Investigation and Processing of Claims § 536.50 Determination of damages—applicable law. (a) The...

  5. Stochastic damage evolution modeling in laminates. Ph.D. Thesis

    SciTech Connect

    Dzenis, Y.A.

    1994-01-01

    A stochastic mesomechanics model has been developed for damage accumulation analysis in advanced laminated composites. The model is based on a theory of excursions of random process beyond the limiting bounds. Stochastic strains in the laminate subjected to random Gaussian in-plane loading are calculated using lamination theory and random functions theory. Probabilistic variation of stiffness and strength characteristics of plies are used in the analysis. A stochastic version of maximum strain failure criterion is applied for damage probability calculation. A mesovolume concept is utilized in modeling stiffness degradation. The model is verified experimentally based on the available data. Capabilities of the model are illustrated by predictions of damage accumulation and failure in a Kevlar/epoxy (0/ +/- 30/90){sub s} laminate under quasistationary, long-term stationary, and cyclic loading. Effects of loading rate, deviation, stationary level and cyclic amplitude on damage evolution are discussed. High-cycle fatigue behavior of laminate is calculated utilizing the observed stages in failure accumulation under the cyclic loading. Percolation type analysis of damage morphology is performed for the inhomogeneous anisotropic media. The model and computer codes developed can be incorporated into structural analysis software and used in design of laminated structures.

  6. Cohesive Laws and Progressive Damage Analysis of Composite Bonded Joints, a Combined Numerical/Experimental Approach

    NASA Technical Reports Server (NTRS)

    Girolamo, Donato; Davila, Carlos G.; Leone, Frank A.; Lin, Shih-Yung

    2015-01-01

    The results of an experimental/numerical campaign aimed to develop progressive damage analysis (PDA) tools for predicting the strength of a composite bonded joint under tensile loads are presented. The PDA is based on continuum damage mechanics (CDM) to account for intralaminar damage, and cohesive laws to account for interlaminar and adhesive damage. The adhesive response is characterized using standard fracture specimens and digital image correlation (DIC). The displacement fields measured by DIC are used to calculate the J-integrals, from which the associated cohesive laws of the structural adhesive can be derived. A finite element model of a sandwich conventional splice joint (CSJ) under tensile loads was developed. The simulations, in agreement with experimental tests, indicate that the model is capable of predicting the interactions of damage modes that lead to the failure of the joint.

  7. Time evolution of damage due to environmentally assisted aging in a fiber bundle model

    NASA Astrophysics Data System (ADS)

    Lennartz-Sassinek, S.; Main, I. G.; Danku, Z.; Kun, F.

    2013-09-01

    Damage growth in composite materials is a complex process which is of interest in many fields of science and engineering. We consider this problem in a fiber bundle model where fibers undergo an aging process due to the accumulation of damage driven by the locally acting stress in a chemically active environment. By subjecting the bundle to a constant external load, fibers fail either when the load on them exceeds their individual intrinsic strength or when the accumulated internal damage exceeds a random threshold. We analyze the time evolution of the breaking process under low external loads where aging of fibers dominates. In the mean field limit, we show analytically that the aging system continuously accelerates in a way which can be characterized by an inverse power law of the event rate with a singularity that defines a failure time. The exponent is not universal; it depends on the details of the aging process. For localized load sharing, a more complex damage process emerges which is dominated by distinct spatial regions of the system with different degrees of stress concentration. Analytical calculations revealed that the final acceleration to global failure is preceded by a stationary accumulation of damage. When the disorder is strong, the accelerating phase has the same functional behavior as in the mean field limit. The analytical results are verified by computer simulations.

  8. Damage evolution in metal matrix composites subjected to thermomechanical fatigue

    SciTech Connect

    Allen, D.H.; Hurtado, L.D.; Helms, K.L.E.

    1995-05-01

    A thermomechanical analysis of unidirectional continuous fiber metal matrix composites is presented. The analysis includes the effects of processing induced residual thermal stresses, interface cracking, and inelastic matrix behavior on damage evolution. Due to the complexity of the nonlinear effects, the analysis is performed computationally using the finite element method. The interface fracture is modeled by a nonlinear constitutive model. The problem formulation is summarized and results are presented for a four-ply unidirectional SCS-6/{beta}21S titanium composite under high temperature isothermal mechanical fatigue.

  9. Simulation of Damage Evolution in Discontinously Reinforced Metal Matrix Composites

    SciTech Connect

    Biner, S.B.; Hu, Shenyang Y.

    2009-08-01

    First, a phase-field model for elastic-plastic solids obeying von Mises yield criterion will be described. Then, this phase-field model will be extended to simulate the damage evolution due to nucleation and growth of voids in ductile matrix for discontinuously reinforced composites. The role of reinforcement morphology and the modulus effects leading to final failure all included in the simulations in an effort to make a parametric investigation. The advantages and disadvantages of such phase-field modeling approach in comparison to well established other continuum methods will be elucidated.

  10. Boundary damage effects on the evolution of creep strain

    NASA Astrophysics Data System (ADS)

    Gullickson, J.; Needleman, A.; Staroselsky, A.; Cassenti, B.

    2008-10-01

    The effect of a reduced section thickness leading to creep strain greater than that observed in the creep response of thicker sections is termed the thickness debit effect. We carry out three-dimensional analyses of the creep response of specimens with rectangular cross sections under uniaxial tensile loading having a boundary damage layer and explore whether this can account for the thickness debit effect. The particular damage mechanism modeled is plastic void nucleation, growth and coalescence with void nucleation taken to be confined to a surface layer and the material characterized as an elastic-power law creeping solid. Three-dimensional transient analyses are carried out but used to simulate quasi-static loading conditions. Results are presented for the effect of the thickness of the boundary damage layer on the creep response. The effect of varying the parameters characterizing the void nucleation process is also investigated. The results qualitatively exhibit a variety of features of the thickness debit effect seen in experiments.

  11. Chromosome damage evolution after low and high LET irradiation

    NASA Astrophysics Data System (ADS)

    Andreev, Sergey; Eidelman, Yuri

    Ionizing radiation induces DNA and chromatin lesions which are converted to chromosome lesions detected in the first post-irradiation mitosis by classic cytogenetic techniques as chromosomal aberrations (CAs). These techniques allow to monitor also delayed aberrations observed after many cell generations post-irradiation - the manifestation of chromosomal instability phenotype (CIN). The problem discussed is how to predict time evolution from initial to delayed DNA/chromosome damage. To address this question, in the present work a mechanistic model of CIN is elaborated which integrates pathways of (*) DNA damage induction and its conversion to chromosome lesions (aberrations), (**) lesion transmission and generation through cell cycles. Delayed aberrations in subsequent cycles are formed in the model owing to two pathways, DNA damage generation de novo as well as CA transmission from previous cycles. DNA damage generation rate is assumed to consist of bystander and non-bystander components. Bystander signals impact all cells roughly equally, whereas non-bystander DSB generation rate differs for the descendants of unirradiated and irradiated cells. Monte Carlo simulation of processes underlying CIN allows to predict the time evolution of initial radiation-induced damage - kinetics curve for delayed unstable aberrations (dicentrics) together with dose response and RBE as a function of time after high vs low LET irradiation. The experimental data for radiation-induced CIN in TK6 lymphoblastoid cells and human lymphocytes irradiated with low (gamma) and high (Fe, C) LET radiation are analyzed on the basis of the proposed model. One of the conclusions is that without bystander signaling, just taking into account the initial DNA damage and non-bystander DSB generation, it is impossible to describe the available experimental data for high-LET-induced CIN. The exact contribution of bystander effects for high vs low LET remains unknown, but the relative contribution may be assessed at large times after initial acute irradiation. RBE for delayed aberrations depends on LET, time and cell line, which probably reflects a genetic background for bystander component. The proposed modeling approach creates a basis for integration of complex network of bystander/inflammatory signaling in systems-level platform for quantification of radiation induced CIN.

  12. Empirical laws of survival and evolution: Their universality and implications

    PubMed Central

    Azbel', Mark Ya.

    1999-01-01

    Presented analysis of human and fly life tables proves that with the specified accuracy their entire survival and mortality curves are uniquely determined by a single point (e.g., by the birth mortality q0), according to the law, which is universal for species as remote as humans and flies. Mortality at any age decreases with the birth mortality q0. According to life tables, in the narrow vicinity of a certain q0 value (which is the same for all animals of a given species, independent of their living conditions), the curves change very rapidly and nearly simultaneously for an entire population of different ages. The change is the largest in old age. Because probability to survive to the mean reproductive age quantifies biological fitness and evolution, its universal rapid change with q0 (which changes with living conditions) manifests a new kind of an evolutionary spurt of an entire population. Agreement between theoretical and life table data is explicitly seen in the figures. Analysis of the data on basic metabolism reduces it to the maximal mean lifespan (for animals from invertebrates to mammals), or to the maximal mean fission time (for bacteria), and universally scales them with the total number of body atoms only. Phenomenological origin of this unification and universality of metabolism, survival, and evolution is suggested. Their implications and challenges are discussed. PMID:10611390

  13. Evolution of the passive film on mechanically damaged nitinol.

    PubMed

    Schroeder, Valeska

    2009-07-01

    The corrosion behavior of Nitinol-based medical implants is critical to their success in vivo. Contemporary Nitinol-based medical implants are typically chemically passivated or electrochemically polished to form a protective passive film. However, mechanically formed surfaces caused by handling damage, fretting, or fatigue fracture may also be present on a device in vivo. In this study, mechanically polished surfaces are used to simulate mechanically damaged surfaces such that analytical techniques, including electrochemical impedance spectroscopy, open circuit potential monitoring, X-ray photoelectron spectroscopy (XPS), and Mott-Schottky analysis may be used to monitor the evolution of the passive film on mechanically damaged Nitinol. These mechanically polished Nitinol surfaces are compared with chemically passivated and electrochemically polished Nitinol surfaces and mechanically polished titanium surfaces in phosphate buffered saline solution. The mechanically polished Nitinol exhibits lower impedance at low frequencies, empirically modeled to a thinner film with lower film resistance than chemically passivated and electrochemically polished Nitinol and mechanically polished titanium. Moreover, the passive film on mechanically polished Nitinol continues to develop over time, increasing in its thickness and film resistance. This characterization demonstrates that mechanically formed surfaces may be initially less protective than chemically passivated and electrochemically polished Nitinol surfaces, but continue to become thicker and more resistant to electrochemical reactions with exposure to saline solution. PMID:18481784

  14. The Evolution of Health Care Advance Planning Law and Policy

    PubMed Central

    Sabatino, Charles P

    2010-01-01

    Context: The legal tools of health care advance planning have substantially changed since their emergence in the mid-1970s. Thirty years of policy development, primarily at the state legislative level addressing surrogate decision making and advance directives, have resulted in a disjointed policy landscape, yet with important points of convergence evolving over time. An understanding of the evolution of advance care planning policy has important implications for policy at both the state and federal levels. Methods: This article is a longitudinal statutory and literature review of health care advance planning from its origins to the present. Findings: While considerable variability across the states still remains, changes in law and policy over time suggest a gradual paradigm shift from what is described as a “legal transactional approach” to a “communications approach,” the most recent extension of which is the emergence of Physician Orders for Life-Sustaining Treatment, or POLST. The communications approach helps translate patients’ goals into visible and portable medical orders. Conclusions: States are likely to continue gradually moving away from a legal transactional mode of advance planning toward a communications model, albeit with challenges to authentic and reliable communication that accurately translates patients’ wishes into the care they receive. In the meantime, the states and their health care institutions will continue to serve as the primary laboratory for advance care planning policy and practice. PMID:20579283

  15. Phase dependent fracture and damage evolution of polytetrafluoroethylene (PTFE)

    SciTech Connect

    Brown, E. N.; Rae, P.; Orler, E. B.; Thissell, W. R.; Dattelbaum, D. M.

    2004-01-01

    Compared with other polymers, polytetrafluoroethylene (PTFE) presents several advantages for load-bearing structural components including higher strength at elevated temperatures and higher toughness at lowered temperatures. Failure sensitive applications of PTFE include surgical implants, aerospace components, and chemical barriers. Polytetrafluoroethylene is semicrystalline in nature with their linear chains forming complicated phases near room temperature and ambient pressure. The presence of three unique phases near room temperature implies that failure during standard operating conditions may be strongly dependent on the phase. This paper presents a comprehensive and systematic study of fracture and damage evolution in PTFE to elicit the effects of temperature-induced phase on fracture mechanisms. The fracture behavior of PTFE is observed to undergo transitions from brittle-fracture below 19 C to ductile-fracture with crazing and some stable crack growth to plastic flow aver 30 C. The bulk failure properties are correlated to failure mechanisms through fractography and analysis of the crystalline structure.

  16. Defect and damage evolution quantification in dynamically-deformed metals using orientation-imaging microscopy

    SciTech Connect

    Gray, George T., III; Livescu, Veronica; Cerreta, Ellen K

    2010-03-18

    Orientation-imaging microscopy offers unique capabilities to quantify the defects and damage evolution occurring in metals following dynamic and shock loading. Examples of the quantification of the types of deformation twins activated, volume fraction of twinning, and damage evolution as a function of shock loading in Ta are presented. Electron back-scatter diffraction (EBSD) examination of the damage evolution in sweeping-detonation-wave shock loading to study spallation in Cu is also presented.

  17. Scale Invariance in Landscape Evolution Models Using Stream Power Laws

    NASA Astrophysics Data System (ADS)

    Kwang, J. S.; Parker, G.

    2014-12-01

    Landscape evolution models (LEM) commonly utilize stream power laws to simulate river incision with formulations such as E = KAmSn, where E is a vertical incision rate [L/T], K is an erodibility constant [L1-2m/T], A is an upstream drainage area [L2], S is a local channel gradient [-], and m and n are positive exponents that describe the basin hydrology. In our reduced complexity model, the landscape approached equilibrium by balancing an incision rate with a constant, uniform, vertical rock uplift rate at every location in the landscape. From our simulations, for a combination of m and n, the landscape exhibited scale invariance. That is, regardless of the size and scale of the basin, the relief and vertical structure of the landscape remained constant. Therefore, the relief and elevation profile of the landscape at equilibrium were only dependent on the coefficients for erodibility and uplift and an equation that described how upstream area, A, increased as the length of a stream increased. In our analytical 1D models, we utilized two equations that described upslope area, (a) A = Bl, where B is the profile width [L], and l is the stream length from the ridge [L] and (b) A = Clh, Hack's Law, where C is a constant [L2-h] and h is a positive exponent. With these equations, (a) m = n and (b) hm = n resulted in scale invariance. In our numerical 2D models, the relationship between A and l was inherent in the actual structure of the drainage network. From our numerical 2D results, scale invariance occurred when 2m = n. Additionally, using reasonable values from the literature for exponents, n, m and h, resulted in singularities at the ridges in the landscape, which caused truncation error. In consequence, the elevation of the ridge increased as the number of grid cells in the domain increased in the numerical model, and the model was unable to converge. These singularities at the ridges appeared when (a) m ≥ n and (b) hm ≥ n in the analytical model and 2m ≥ n in the numerical model. Here we present (1) 1D analytical solutions and (2) 2D numerical solutions that demonstrate scale invariance in LEMs and (3) the consequences of the singularity in 2D LEM numerical simulations. These results will help provide insight about the structure and dynamics of landscapes and drainage networks and shed light on geomorphological empirical relationships.

  18. On-site inspections of pavement damages evolution using GPR

    NASA Astrophysics Data System (ADS)

    Tosti, Fabio; D'Amico, Fabrizio; Calvi, Alessandro; Benedetto, Andrea

    2014-05-01

    Ground-penetrating radar (GPR) is being increasingly used for pavements maintenance due to the wide range of applications spanning from physical to geometrical inspections, thereby allowing for a reliable diagnosis of the main causes of road structural damages. In this work, an off-ground GPR system was used to investigate a large-scale rural road network. Two sets of surveys were carried out in different time periods, with the main goals to i) localize the most critical sections; ii) monitor the evolution of previous damages and localize newborn deep faults, although not revealed at the pavement surface level; iii) analyze the causes of both evolution and emergence of faults by considering environmental and human factors. A 1-GHz GPR air-launched antenna was linked to an instrumented van for collecting data at traffic speed. Other support techniques (e.g. GPS data logger, odometer, HD video camera) were used for cross-checking,. Such centre frequency of investigation along with a 25-ns time window allow for a signal penetration of 900 mm, consistent with the deepest layer interfaces. The bottom of the array was 400 mm over the surface, with a minimum distance of 1200 mm from the van body. Scan length of maximum 10 km were provided for avoiding heavy computational loads. The rural road network was located in the District of Rieti, 100 km north from Rome, Italy, and mostly develops in a hilly and mountainous landscape. In most of the investigated roads, the carriageway consists in two lanes of 3.75 meters wide and two shoulders of 0.50 meters wide. A typical road section includes a HMA layer (65 mm average thickness), a base layer (100 mm average thickness), and a subbase layer (300 mm average thickness), as described by pavement design charts. The first set of surveys was carried out in two days at the beginning of spring in moderately dry conditions. Overall, 320-km-long inspections were performed in both travel directions, thereby showing a productivity of approximately 160 km/day at 40 km/h speed, on the average. After processing and first-checking, GPR profiles were divided into homogeneous sections according to the combination of different parameters (e.g. route analyzed, long distance conditions of regularity/irregularity in layers arrangement). In such context, a high consistency between surface damages, mismatches from the GPR scans, and boundary environmental conditions was demonstrated. In addition, deep mismatches were detected even for early-stage or unrevealed faults. The second set of surveys was carried out in autumn in high humidity conditions, due to recent rainfalls. 160 km of relevant routes from the same road network were investigated. Results showed a high consistency with those collected during the first-stage of surveys. Minor changes were found in those sections with low traffic loads (e.g. farther away from the biggest town of Rieti), whereas major mismatches were detected in wetlands (e.g. close to rivers), work zones, and nearby those sections already deeply damaged in the past. This work benefited from networking activities carried out within the EU funded COST Action TU1208 'Civil Engineering Applications of Ground Penetrating Radar'.

  19. A biophysical model of cell evolution after cytotoxic treatments: Damage, repair and cell response.

    PubMed

    Tomezak, M; Abbadie, C; Lartigau, E; Cleri, F

    2016-01-21

    We present a theoretical agent-based model of cell evolution under the action of cytotoxic treatments, such as radiotherapy or chemotherapy. The major features of cell cycle and proliferation, cell damage and repair, and chemical diffusion are included. Cell evolution is based on a discrete Markov chain, with cells stepping along a sequence of discrete internal states from 'normal' to 'inactive'. Probabilistic laws are introduced for each type of event a cell can undergo during its life: duplication, arrest, senescence, damage, reparation, or death. We adjust the model parameters on a series of cell irradiation experiments, carried out in a clinical LINAC, in which the damage and repair kinetics of single- and double-strand breaks are followed. Two showcase applications of the model are then presented. In the first one, we reconstruct the cell survival curves from a number of published low- and high-dose irradiation experiments. We reobtain a very good description of the data without assuming the well-known linear-quadratic model, but instead including a variable DSB repair probability. The repair capability of the model spontaneously saturates to an exponential decay at increasingly high doses. As a second test, we attempt to simulate the two extreme possibilities of the so-called 'bystander' effect in radiotherapy: the 'local' effect versus a 'global' effect, respectively activated by the short-range or long-range diffusion of some factor, presumably secreted by the irradiated cells. Even with an oversimplified simulation, we could demonstrate a sizeable difference in the proliferation rate of non-irradiated cells, the proliferation acceleration being much larger for the global than the local effect, for relatively small fractions of irradiated cells in the colony. PMID:26549470

  20. Numerical Simulation of Rock Mass Damage Evolution During Deep-Buried Tunnel Excavation by Drill and Blast

    NASA Astrophysics Data System (ADS)

    Yang, Jianhua; Lu, Wenbo; Hu, Yingguo; Chen, Ming; Yan, Peng

    2015-09-01

    Presence of an excavation damage zone (EDZ) around a tunnel perimeter is of significant concern with regard to safety, stability, costs and overall performance of the tunnel. For deep-buried tunnel excavation by drill and blast, it is generally accepted that a combination of effects of stress redistribution and blasting is mainly responsible for development of the EDZ. However, few open literatures can be found to use numerical methods to investigate the behavior of rock damage induced by the combined effects, and it is still far from full understanding how, when and to what degree the blasting affects the behavior of the EDZ during excavation. By implementing a statistical damage evolution law based on stress criterion into the commercial software LS-DYNA through its user-subroutines, this paper presents a 3D numerical simulation of the rock damage evolution of a deep-buried tunnel excavation, with a special emphasis on the combined effects of the stress redistribution of surrounding rock masses and the blasting-induced damage. Influence of repeated blast loadings on the damage extension for practical millisecond delay blasting is investigated in the present analysis. Accompanying explosive detonation and secession of rock fragments from their initial locations, in situ stress in the immediate vicinity of the excavation face is suddenly released. The transient characteristics of the in situ stress release and induced dynamic responses in the surrounding rock masses are also highlighted. From the simulation results, some instructive conclusions are drawn with respect to the rock damage mechanism and evolution during deep-buried tunnel excavation by drill and blast.

  1. Scaling laws for convection with temperature-dependent viscosity and grain-damage

    NASA Astrophysics Data System (ADS)

    Foley, Bradford J.; Bercovici, David

    2014-10-01

    Numerical experiments of convection with grain-damage are used to develop scaling laws for convective heat flow, mantle velocity and plate velocity across the stagnant lid and plate-tectonic regimes. Three main cases are presented in order of increasing complexity: a simple case wherein viscosity is only dependent on grain size, a case where viscosity depends on temperature and grain size, and finally a case where viscosity is temperature and grain size sensitive, and the grain-growth (or healing) is also temperature sensitive. In all cases, convection with grain-damage scales differently than Newtonian convection; whereas the Nusselt number (Nu), typically scales with the reference Rayleigh number, Ra0, to the 1/3 power, for grain-damage this exponent is larger because increasing Ra0 also enhances damage. In addition, Nu, mantle velocity, and plate velocity are also functions of the damage to healing ratio, (D/H); increasing D/H increases Nu because more damage leads to more vigorous convection. For the fully realistic case, numerical results show stagnant lid convection, fully mobilized convection that resembles the temperature-independent viscosity case, and partially mobile or transitional convection, depending on D/H, Ra0, and the activation energies for viscosity and healing. Applying our scaling laws for the fully realistic case to Earth and Venus we demonstrate that increasing surface temperature dramatically decreases plate speed and heat flow, essentially shutting down plate tectonics, due to increased healing in lithospheric shear zones, as proposed previously. Contrary to many previous studies, the transitional regime between the stagnant lid and fully mobilized regimes is large, and the transition from stagnant lid to mobile convection is gradual and continuous. Thus planets could exhibit a full range of surface mobility, as opposed to the bimodal distribution of fully mobile lid planets and stagnant lid planets that is typically assumed.

  2. The evolution of Zipf's law indicative of city development

    NASA Astrophysics Data System (ADS)

    Chen, Yanguang

    2016-02-01

    Zipf's law of city-size distributions can be expressed by three types of mathematical models: one-parameter form, two-parameter form, and three-parameter form. The one-parameter and one of the two-parameter models are familiar to urban scientists. However, the three-parameter model and another type of two-parameter model have not attracted attention. This paper is devoted to exploring the conditions and scopes of application of these Zipf models. By mathematical reasoning and empirical analysis, new discoveries are made as follows. First, if the size distribution of cities in a geographical region cannot be described with the one- or two-parameter model, maybe it can be characterized by the three-parameter model with a scaling factor and a scale-translational factor. Second, all these Zipf models can be unified by hierarchical scaling laws based on cascade structure. Third, the patterns of city-size distributions seem to evolve from three-parameter mode to two-parameter mode, and then to one-parameter mode. Four-year census data of Chinese cities are employed to verify the three-parameter Zipf's law and the corresponding hierarchical structure of rank-size distributions. This study is revealing for people to understand the scientific laws of social systems and the property of urban development.

  3. Experimental and Analytical Evaluation of Stressing-Rate State Evolution in Rate-State Friction Laws

    NASA Astrophysics Data System (ADS)

    Bhattacharya, P.; Rubin, A. M.; Bayart, E.; Savage, H. M.; Marone, C.; Beeler, N. M.

    2013-12-01

    Standard rate and state friction laws fail to explain the full range of observations from laboratory friction experiments. A new state evolution law has been proposed by Nagata et al. (2012) that adds a linear stressing-rate-dependent term to the Dieterich (aging) law, which may provide a remedy. They introduce a parameter c that controls the contribution of the stressing rate to state evolution. We show through analytical approximations that the new law can transition between the responses of the traditional Dieterich (aging) and Ruina (slip) laws in velocity step up/down experiments when the value of c is tuned properly. In particular, for c = 0 the response is pure aging while for finite, non-zero c one observes slip law like behavior for small velocity jumps but aging law like response for larger jumps. The magnitude of the velocity jump required to see this transition between aging and slip behaviour increases as c increases. In the limit of c >> 1 the response to velocity steps becomes purely slip law like. In this limit, numerical simulations show that this law loses its appealing time dependent healing property. An approach using Markov Chain Monte Carlo parameter search on data for large magnitude velocity step tests reveals that it is only possible to determine a lower bound on c using datasets that are well explained by the slip law. For a dataset with velocity steps of two orders of magnitude on simulated fault gouge we find this lower bound to be c ≈ 10.0. This is significantly larger than c ≈ 2.0 used by Nagata et al. (2012) to fit their data (mainly bare rock experiments with smaller excursions from steady state than our dataset). Similar parameter estimation exercises on slide hold slide data reveal that none of the state evolution laws considered - Dieterich, Ruina, Kato-Tullis and Nagata - match the relevant features of the data. In particular, even the aging law predicts only the correct rate of healing for long hold times but not the correct amount of healing. For c = 10.0, the Nagata law shows significant slip dependence in healing rate for long hold times which is at odds with the lab data and similar to the slip law response. If one accepts frictional healing observed in the laboratory as a ';proper' analog for fault strengthening over the interseismic period, we conclude that none of the investigated state evolution laws provides a comprehensive and correct constitutive relation.

  4. The Coffin-Manson law as a consequence of the statistical nature of the LCF surface damage

    NASA Astrophysics Data System (ADS)

    Brechet, Y.; Magnin, T.; Sornette, D.

    1992-09-01

    The transition between the Coffin-Manson law in low cycle fatigue and the Basquin law in high cycle fatigue is shown to be closely related to the microstructural aspects of damage accumulation in the two different fatigue domains. In LCF, the surface extension of microcracks is predominant whereas their bulk propagation is dominating in HCF. Along these lines, the Coffin-Manson law is derived using standard methods of statistical physics of disordered systems. The university of the Coffin-Manson exponent for single-phased materials is shown to be a direct consequence of the statistical nature of damage accumulation due to the growth and the interaction of surface microcracks.

  5. [Evolution of pharmaceutical regulations from the origins to Germinal law].

    PubMed

    Lafont, Olivier

    2003-01-01

    The rising of pharmaceutical regulations took place in the civilisations located around the Mediterranean Sea. Egypt, Mesopotamia, Greco-Roman world, Byzantine Empire, were followed by Bagdad, where sayadila, inspections and grabadins appeared. The creation of Universities, during the XIIth and XIIIth centuries, plaid a role in the rising of apothecaries communities in Occident. Melfi Constitutions (Constititiones Melfiae, 1231) and new constitutions (1241) inspired most of the regulations of apothecaries communities in Europe. Declaration of the King of France in April 1777 announced the famous "Loi de Germinal", Germinal law, which organized the modern Pharmacy, in 1803. PMID:14763458

  6. The Evolution of the Exponent of Zipf's Law in Language Ontogeny

    PubMed Central

    Baixeries, Jaume; Elvevåg, Brita; Ferrer-i-Cancho, Ramon

    2013-01-01

    It is well-known that word frequencies arrange themselves according to Zipf's law. However, little is known about the dependency of the parameters of the law and the complexity of a communication system. Many models of the evolution of language assume that the exponent of the law remains constant as the complexity of a communication systems increases. Using longitudinal studies of child language, we analysed the word rank distribution for the speech of children and adults participating in conversations. The adults typically included family members (e.g., parents) or the investigators conducting the research. Our analysis of the evolution of Zipf's law yields two main unexpected results. First, in children the exponent of the law tends to decrease over time while this tendency is weaker in adults, thus suggesting this is not a mere mirror effect of adult speech. Second, although the exponent of the law is more stable in adults, their exponents fall below 1 which is the typical value of the exponent assumed in both children and adults. Our analysis also shows a tendency of the mean length of utterances (MLU), a simple estimate of syntactic complexity, to increase as the exponent decreases. The parallel evolution of the exponent and a simple indicator of syntactic complexity (MLU) supports the hypothesis that the exponent of Zipf's law and linguistic complexity are inter-related. The assumption that Zipf's law for word ranks is a power-law with a constant exponent of one in both adults and children needs to be revised. PMID:23516390

  7. Effects of grain size distribution on the creep damage evolution of polycrystalline materials

    NASA Astrophysics Data System (ADS)

    Yu, Tao; Shi, Huiji

    2010-04-01

    It is evident that realistic microstructures of polycrystalline materials demonstrate a certain distribution of grain size, which has not been widely studied in most analyses of mechanical properties of materials at high temperatures. In this work, the effects of grain size distribution on the creep damage evolution induced by void growth of polycrystalline materials were investigated by the Voronoi tessellation approach, taking into account the void evolution on the grain boundaries in a grain aggregate cell. The results indicate that with the decrease in mean grain size, the damage variable increases faster. When the mean grain sizes are the same, the more uniform the grain size is, the faster the damage variable increases.

  8. A universal scaling law for the evolution of granular gases

    NASA Astrophysics Data System (ADS)

    Hummel, Mathias; Clewett, James P. D.; Mazza, Marco G.

    2016-04-01

    Dry, freely evolving granular materials in a dilute gaseous state coalesce into dense clusters only due to dissipative interactions. Here we show that the evolution of a dilute, freely cooling granular gas is determined in a universal way by the ratio of inertial flow and thermal velocities, that is, the Mach number. Theoretical calculations and direct numerical simulations of the granular Navier-Stokes equations show that irrespective of the coefficient of restitution, density or initial velocity distribution, the density fluctuations follow a universal quadratic dependence on the system's Mach number. We find that the clustering exhibits a scale-free dynamics but the clustered state becomes observable when the Mach number is approximately of O(1) . Our results provide a method to determine the age of a granular gas and predict the macroscopic appearance of clusters.

  9. A universal scaling law for the evolution of granular gases

    NASA Astrophysics Data System (ADS)

    Hummel, Mathias; Clewett, James; Mazza, Marco G.

    Dry, freely evolving granular materials in a dilute gaseous state coalesce into dense clusters only due to dissipative interactions. This clustering transition is important for a number of problems ranging from geophysics to cosmology. Here we show that the evolution of a dilute, freely cooling granular gas is determined in a universal way by the ratio of inertial flow and thermal velocities, that is, the Mach number. Theoretical calculations and direct numerical simulations of the granular Navier-Stokes equations show that irrespective of the coefficient of restitution, density or initial velocity distribution, the density fluctuations follow a universal quadratic dependence on the system's Mach number. We find that the clustering exhibits a scale-free dynamics but the clustered state becomes observable when the Mach number is approximately of O(1). Our results provide a method to determine the age of a granular gas and predict the macroscopic appearance of clusters.

  10. Information Theory, Scaling Laws and the Thermodynamics of Evolution.

    PubMed

    Wallace; Wallace

    1998-06-21

    Renormalization symmetry and the Legendre transformation are imposed on a parametized form of ergodic source uncertainty, a widely-applied model for "languages" ranging from the spoken word to genetic codes. Using the Shannon-McMillan theorem to identify a duality between source uncertainty and free energy density, this procedure: (i) suggests that a punctuated "phase change" and resulting sudden fragmentation or coalescence should be the norm for "language"-based phenomena, particularly the transfer of "genetic" information within reproducing populations; (ii) gives a power law for that phase change near transition; (iii) provides a "disorder" construct similar to an entropy which may trigger higher degrees of punctuation in social systems than is suggested from simple physical analogs; and (iv) gives "equations of state" relating ensemble averages which should be observable within coalesced systems. The general formalism is explicitly applied to problems of speciation, coevolution and group selection, and comparison made with the work of Eigen and his associates.Copyright 1998 Academic Press Limited PMID:9782104

  11. Statistical distribution of laser damage and spatial scaling law for a model with multiple defect cooperation in damage

    NASA Astrophysics Data System (ADS)

    Bercegol, Herve

    2000-03-01

    A simple model is proposed, featuring cooperation of many defects to the damage process. For identical, randomly and independently distributed defects, the response of the optical components to a spatially gaussian laser pulse is calculated. The absorption response of the component is a probability distribution, which depends on the values of mean defect density and beam equivalent area. For a damage threshold expressed as a value of the absorbed energy, the statistical distribution of damage in obtained theoretically, as a function of fluence. The damage fluence distribution resembles the lognormal function found in many recent experimental measurements. Damage statistics were also calculated for a diverse spatial dimensions of the beam. This cooperative model of a damage is compared to the description of defect-related damage developed in particular by Mike Feit et al to correlate small beam damage test to large area irradiation results. In the latter work ,defects react one by one, contrary to the present view.

  12. Exploring the effect of power law social popularity on language evolution.

    PubMed

    Gong, Tao; Shuai, Lan

    2014-01-01

    We evaluate the effect of a power-law-distributed social popularity on the origin and change of language, based on three artificial life models meticulously tracing the evolution of linguistic conventions including lexical items, categories, and simple syntax. A cross-model analysis reveals an optimal social popularity, in which the λ value of the power law distribution is around 1.0. Under this scaling, linguistic conventions can efficiently emerge and widely diffuse among individuals, thus maintaining a useful level of mutual understandability even in a big population. From an evolutionary perspective, we regard this social optimality as a tradeoff among social scaling, mutual understandability, and population growth. Empirical evidence confirms that such optimal power laws exist in many large-scale social systems that are constructed primarily via language-related interactions. This study contributes to the empirical explorations and theoretical discussions of the evolutionary relations between ubiquitous power laws in social systems and relevant individual behaviors. PMID:24730762

  13. von Baer's law for the ages: lost and found principles of developmental evolution.

    PubMed

    Abzhanov, Arhat

    2013-12-01

    In 1828, Karl Ernst von Baer formulated a series of empirically defined rules, which became widely known as the 'Law of Development' or 'von Baer's law of embryology'. This was one the most significant attempts to define the principles that connected morphological complexity and embryonic development. Understanding this relation is central to both evolutionary biology and developmental genetics. Von Baer's ideas have been both a source of inspiration to generations of biologists and a target of continuous criticism over many years. With advances in multiple fields, including paleontology, cladistics, phylogenetics, genomics, and cell and developmental biology, it is now possible to examine carefully the significance of von Baer's law and its predictions. In this review, I argue that, 185 years after von Baer's law was first formulated, its main concepts after proper refurbishing remain surprisingly relevant in revealing the fundamentals of the evolution-development connection, and suggest that their explanation should become the focus of renewed research. PMID:24120296

  14. General introduction to microstructural evolution under cascade damage conditions

    SciTech Connect

    Wiedersich, H.

    1993-06-01

    A short overview of the processes that affect the evolution of the microstructure during irradiation is given. The processes include defect production with an emphasis on the effects of the dynamic cascade events, defect clustering, irradiation-enhanced diffusion, radiation-induced segregation, phase decompositions and phase transformations. A simple model for the description of the development of the defect microstructure in a pure metal during cascade producing irradiation is also outlined which can provide, in principle, defect fluxes required for the description of the microstructural processes such as phase decomposition and irradiation-induced precipitation.

  15. Studying the laws of software evolution in a long-lived FLOSS project

    PubMed Central

    Gonzalez-Barahona, Jesus M; Robles, Gregorio; Herraiz, Israel; Ortega, Felipe

    2014-01-01

    Some free, open-source software projects have been around for quite a long time, the longest living ones dating from the early 1980s. For some of them, detailed information about their evolution is available in source code management systems tracking all their code changes for periods of more than 15 years. This paper examines in detail the evolution of one of such projects, glibc, with the main aim of understanding how it evolved and how it matched Lehman's laws of software evolution. As a result, we have developed a methodology for studying the evolution of such long-lived projects based on the information in their source code management repository, described in detail several aspects of the history of glibc, including some activity and size metrics, and found how some of the laws of software evolution may not hold in this case. © 2013 The Authors. Journal of Software: Evolution and Process published by John Wiley & Sons Ltd. PMID:25893093

  16. Influence of tensile duration on dynamically induced damage evolution of OFHC

    NASA Astrophysics Data System (ADS)

    Xiaoyang, Pei; Hongliang, He; Ping, Li; Hui, Peng; Dynamic Damage Evolution Team

    2013-06-01

    Plate impact experiments have been carried out to examine the influence of tensile duration on dynamically induced damage evolution of OFHC. A new double-layer-sample target experimental technique, tentatively termed as damage-frozen technique, is presented in this paper, with which the tensile duration can be controlled. The experimental configuration used in this work permits real-time (VISAR) measurements of the second sample free surface velocity histories and post experiment metallurgical analysis of the soft recovered samples. It is shown that for the same dynamic loading profile but different tensile duration, the free surface velocity profiles are nearly the same, with only differences in the slope between the pull-back minima and spall peak, but pre-spall damage including number, size and distribution of the void are significantly different. Based on these results, the relationship between wave profiles and damage evolution with different tensile duration time is established.

  17. Rheological Control of Interbedded Siliciclastic Strata on Damage Zone Evolution During Fault Growth

    NASA Astrophysics Data System (ADS)

    Wightman, R. H.; Imber, J.; Healy, D.; Holdsworth, R. E.; McCaffrey, K. J.; Jones, R. R.

    2006-12-01

    Fault damage zones can have a major impact on fluid flow through sub-surface reservoirs. The typical resolution of seismic reflection data is such that faults with throws <15m are not imaged, and those with throws >15 m are imaged as discrete planes, revealing none of the smaller scale architecture of the fault damage zones. Previous field studies show that damage zone width scales with fault throw, which suggests that a relationship exists between fault growth and increasing damage zone width. However, this hypothesis remains largely untested and the factors controlling damage zone evolution are poorly understood. This study develops kinematic models to describe the evolution of damage zones during fault growth. The predictions of these models are tested against quantitative geometric attributes of natural fault damage zones preserved in siliciclastic sand/shale sequences from the Carboniferous Northumberland Basin, NE England. These data, obtained from faults with throws spanning 0.1-20 m, were measured from detailed (cm-resolution) digital outcrop models captured using terrestrial laser scanning techniques. Study locations include areas of active open-cast coal mining that provide good 3D exposure of faults during progressive coal extraction. The damage zones comprise complex arrays of structural elements including: fault splays and oversteps; drag folds; rotated fault-bound blocks; sub-parallel fracture sets and ductile shear zones; cataclasite lenses; and intensely deformed scaly gouge. We propose two complimentary kinematic models to explain the structural relationships observed within these damage zones. The first model predicts the development of cataclasite lenses from fault-bounded blocks in contractional oversteps with increasing fault throw. In this scenario, the damage zone width remains approximately constant, defined by the initial fault separation. The second model describes the space incompatibility that develops between discrete fault planes in coherent sandstone layers and wider damage zones in adjacent shales where throw is distributed along sub-parallel fracture sets and ductile shear zones. In this scenario, damage zone width may increase with increasing fault throw. Alternatively, the width of the damage zone may be controlled by thickness of the rheologically weaker shale. These geologically-based models highlight the importance of bed thickness and rheology - in addition to fault throw - in controlling damage zone evolution and provide a basis for predicting the likely sizes of different damage zone elements associated with seismically-imaged faults in the subsurface.

  18. Dynamic damage evolution of solids in compression: Microcracking, plastic flow, and brittle-ductile transition

    SciTech Connect

    Deng, H.; Nemat-Nasser, S. . Center of Excellence for Advanced Materials)

    1994-07-01

    Dynamic compressive damage evolution in solids, associated with brittle microcracking and ductile plastic flow, is modeled through plastic flow and tensile microcracking, which are induced by the deformation of preexisting microflaws at grain boundaries, slip bands, and microcavities. The micromechanical aspect of this model is discussed in terms of the dominance of microcracking or plastic flow, and possible transition from microcracking to plastic flow is investigated. The effect of lateral confinement on the dynamic damage evolution is investigated, emphasizing the brittle-ductile transition.

  19. The Coffin-Manson law as a consequence of the statistical nature of the LCF surface damage

    SciTech Connect

    Brechet, Y.; Magnin, T.; Sornette, D. Lille I, Universite, Villeneuve-d'Ascq Nice, Universite, )

    1992-09-01

    The transition between the Coffin-Manson law in low cycle fatigue and the Basquin law in high cycle fatigue is shown to be closely related to the microstructural aspects of damage accumulation in the two different fatigue domains. In LCF, the surface extension of microcracks is predominant whereas their bulk propagation is dominating in HCF. Along these lines, the Coffin-Manson law is derived using standard methods of statistical physics of disordered systems. The university of the Coffin-Manson exponent for single-phased materials is shown to be a direct consequence of the statistical nature of damage accumulation due to the growth and the interaction of surface microcracks. 22 refs.

  20. Microstructure: Property correlation. [multiaxial fatigue damage evolution in waspaloy

    NASA Technical Reports Server (NTRS)

    Jayaraman, N.

    1990-01-01

    Strain controlled torsional and biaxial (tension-torsion) low cycle fatigue behavior of Waspaloy was studied at room temperature as a function of heat treatment. Biaxial tests were conducted under proportional (when the axial and torsional strain cycles are in-phase) and non-proportional (when the axial and torsional strain cycles are 90 deg out-of-phase) cyclic conditions. The deformation behavior under these different cyclic conditions were evaluated by slip trace analysis. For this, a Schmidt-type factor was defined for multiaxial loading conditions and it was shown that when the slip deformation is predominant, non-proportional cycles are more damaging than proportional or pure axial or torsional cycles. This was attributed to the fact that under non-proportional cyclic conditions, deformation was through multiple slip as opposed single slip for other loading conditions, which gave rise to increased hardening. The total life for a given test condition was found to be independent of heat treatment. This was interpreted as being due to the differences in the cycles to initiation and propagation of cracks.

  1. Ductile damage evolution and experimental simulation under high rates of strain in 10100 copper.

    SciTech Connect

    Thissell, W. R.; McKirgan, J. B.; Chen, S. R.; Trujillo, C. P.; Macdougall, D. A. S.

    2001-01-01

    The high strain-rate damage evolution and Eracture behavior of half-hard 10 LOO Cu was investigated by experiments and computer simulations. Testing of uniaxial stress and axisymmetric notched bars of the Hancock-Mackenzie geometries were performetl using a momentum trapped tensile split Hopkinson pressure bar. Specimens were. tested to fracture and to several stages of incipient failure prior to fracture. Recovered specimens were sectioned and metallographically examined using image analysis and optical profilornelry to quantify the resulting damage. The quantified damage is described by spatially resolved porosity distributions, spatially resolved volumetric number densiries, and spatia Ily resolved void size distributions. Concurrent to mechanical testing, explicit finite element simulations of the tensile split Hopkinson pressure bar experiments were perfornicd to quantify the local stress-state and strain-state within the material and to determine the evolution of damage within the notch region. The coinpressive plasticity behavior of the material was fit to the mechanical threshold stress constitutive model, and was used in the simulations. The quantified damage was coniprued with damage model (TEPLA) predictions and used to refine model parameters and damage nucleation criteria. The simulation results also show that the maximum stress triaxiality in the specimens quickly enlarges after the onset of plastic flow or tensile instability to almost twice that of the Bridgman predicted levels.

  2. Radiation-induced damage and evolution of defects in Mo

    SciTech Connect

    Starikov, Sergey V.; Insepov, Zeke; Rest, Jeffrey; Kuksin, Alexey Yu.; Norman, Genri E.; Stegailov, Vladimir V.; Yanilkin, Alexey V.

    2011-09-01

    The formation of defects in bcc Mo lattice as a result of 50-keV Xe bombardment is studied via atomistic simulation with an interatomic potential developed using the force-matching ab initio based approach. The defect evolution in the cascade is described. Diffusion and interaction of interstitials and vacancies are analyzed. Only small interstitial atom clusters form directly in the cascade. Larger clusters grow only via aggregation at temperatures up to 2000 K. Stable forms of clusters demonstrate one-dimensional diffusion with a very high diffusion coefficient and escape quickly to the open surface. Point vacancies have much lower diffusivity and do not aggregate. The possibility of a large prismatic vacancy loop formation near the impact surface as a result of fast recrystallization is revealed. The mobility of the vacancy dislocation loop segments is high, however, the motion of the entire loops is strongly hindered by neighbor point defects. This paper explains the existence of the large prismatic vacancy loops and the absence of the interstitial loops in the recent experiments with ion irradiation of Mo foils.

  3. Asymmetrical Damage Partitioning in Bacteria: A Model for the Evolution of Stochasticity, Determinism, and Genetic Assimilation

    PubMed Central

    Chao, Lin; Rang, Camilla Ulla; Proenca, Audrey Menegaz; Chao, Jasper Ubirajara

    2016-01-01

    Non-genetic phenotypic variation is common in biological organisms. The variation is potentially beneficial if the environment is changing. If the benefit is large, selection can favor the evolution of genetic assimilation, the process by which the expression of a trait is transferred from environmental to genetic control. Genetic assimilation is an important evolutionary transition, but it is poorly understood because the fitness costs and benefits of variation are often unknown. Here we show that the partitioning of damage by a mother bacterium to its two daughters can evolve through genetic assimilation. Bacterial phenotypes are also highly variable. Because gene-regulating elements can have low copy numbers, the variation is attributed to stochastic sampling. Extant Escherichia coli partition asymmetrically and deterministically more damage to the old daughter, the one receiving the mother’s old pole. By modeling in silico damage partitioning in a population, we show that deterministic asymmetry is advantageous because it increases fitness variance and hence the efficiency of natural selection. However, we find that symmetrical but stochastic partitioning can be similarly beneficial. To examine why bacteria evolved deterministic asymmetry, we modeled the effect of damage anchored to the mother’s old pole. While anchored damage strengthens selection for asymmetry by creating additional fitness variance, it has the opposite effect on symmetry. The difference results because anchored damage reinforces the polarization of partitioning in asymmetric bacteria. In symmetric bacteria, it dilutes the polarization. Thus, stochasticity alone may have protected early bacteria from damage, but deterministic asymmetry has evolved to be equally important in extant bacteria. We estimate that 47% of damage partitioning is deterministic in E. coli. We suggest that the evolution of deterministic asymmetry from stochasticity offers an example of Waddington’s genetic assimilation. Our model is able to quantify the evolution of the assimilation because it characterizes the fitness consequences of variation. PMID:26761487

  4. Asymmetrical Damage Partitioning in Bacteria: A Model for the Evolution of Stochasticity, Determinism, and Genetic Assimilation.

    PubMed

    Chao, Lin; Rang, Camilla Ulla; Proenca, Audrey Menegaz; Chao, Jasper Ubirajara

    2016-01-01

    Non-genetic phenotypic variation is common in biological organisms. The variation is potentially beneficial if the environment is changing. If the benefit is large, selection can favor the evolution of genetic assimilation, the process by which the expression of a trait is transferred from environmental to genetic control. Genetic assimilation is an important evolutionary transition, but it is poorly understood because the fitness costs and benefits of variation are often unknown. Here we show that the partitioning of damage by a mother bacterium to its two daughters can evolve through genetic assimilation. Bacterial phenotypes are also highly variable. Because gene-regulating elements can have low copy numbers, the variation is attributed to stochastic sampling. Extant Escherichia coli partition asymmetrically and deterministically more damage to the old daughter, the one receiving the mother's old pole. By modeling in silico damage partitioning in a population, we show that deterministic asymmetry is advantageous because it increases fitness variance and hence the efficiency of natural selection. However, we find that symmetrical but stochastic partitioning can be similarly beneficial. To examine why bacteria evolved deterministic asymmetry, we modeled the effect of damage anchored to the mother's old pole. While anchored damage strengthens selection for asymmetry by creating additional fitness variance, it has the opposite effect on symmetry. The difference results because anchored damage reinforces the polarization of partitioning in asymmetric bacteria. In symmetric bacteria, it dilutes the polarization. Thus, stochasticity alone may have protected early bacteria from damage, but deterministic asymmetry has evolved to be equally important in extant bacteria. We estimate that 47% of damage partitioning is deterministic in E. coli. We suggest that the evolution of deterministic asymmetry from stochasticity offers an example of Waddington's genetic assimilation. Our model is able to quantify the evolution of the assimilation because it characterizes the fitness consequences of variation. PMID:26761487

  5. Damage and permiability evolution in creep-failed microgranite

    NASA Astrophysics Data System (ADS)

    Odling, N.; Elphick, S.; Main, I.; Meredith, P.; Ngwenya, B.

    2003-04-01

    The importance of crack generation during deformation is now becoming widely recognized as one of the key factors that control important processes involving fluid flow in rocks of low permeability e.g., hydro-thermal circulation at mid-ocean ridges, energy recovery from geothermal reservoirs, and accelerating deformation preceding volcanic eruptions. Here we describe experiments that extend the study of Meredith et al. (2000) by examining the relationship between slow deformation, the growth of micro-fractures, and permeability in Ailsa Craig microgranite (ACM) close to the fracture interconnection percolation threshold. To examine the inter-relationship between the above factors we have undertaken creep experiments on cores of ACM during which we have measured acoustic emissions, solute breakthrough curves, and electrical impedance (EI), at a strain rate of 10e(-6). The initial network of distributed damage was generated in a 38mm-diameter core of ACM by heating at 1°C/hr to 900°C then cooling to room temperature at the same rate. The treated core was then placed in a Hasler cell with integral acoustic emission and electrical impedance sensors and initially loaded to 20MPa. To measure breakthrough curves, solutions of deionized/distilled/degassed water was alternated with a degassed 1M NaCl solution at a flow rate of 1cc/hr. Differential fluid pressures were monitored by piezoelectric pressure gauges and the strain in the sample was monitored by LVDTs attached to the pistons. Initial 'breakthrough' tests under hydrostatic conditions show that the EI response detects first a linear change in impedance as the solute front advances through the core followed by a more gradual decrease as the front ‘breaks out’ of the core end. The EI response, therefore, describes both the advection and dispersion terms associated with the solute front in the core. The data allow the inter-relationship between crack generation/growth, effective cumulative aperture, permeability and hydraulic dispersion to be examined during the process of creep deformation. Of particular interest is the behaviour of the system close to failure, where rapid changes in fracture network characteristics occur.

  6. Damage evolution in Au-implanted Ho2Ti2O7 titanate pyrochlore

    SciTech Connect

    Zhang, Yanwen; Jagielski, Jacek; Bae, In-Tae; Xiang, Xia; Thome, Lionel; Balakrishnan, G.; Paul, D. M.; Weber, William J.

    2010-10-01

    Damage evolution at room temperature in Ho2Ti2O7 single crystals is studied under 1 MeV Au2+ ion irradiation by Rutherford backscattering spectroscopy along the <001> direction. For a better determination of ion-induced disorder profile, an iterative procedure and a Monte Carlo code (McChasy) were used to analyze ion channeling spectra. A disorder accumulation model, with contributions from the amorphous fraction and the crystalline disorder, is fit to the Ho damage accumulation data. The damage evolution behavior indicates that the relative disorder on the Ho sublattice follows a nonlinear dependence on dose and that defect-stimulated amorphization is the primary amorphization mechanism. Similar irradiation behavior previously was observed in Sm2Ti2O7. A slower damage accumulation rate for Ho2Ti2O7, as compared with damage evolution in Sm2Ti2O7, is mainly attributed to a lower effective cross section for defect-simulated amorphization.

  7. Numerical Simulations of Inter-laminar Damage Evolution in a Composite Wing Box

    NASA Astrophysics Data System (ADS)

    Riccio, A.; Raimondo, A.; Borrelli, R.; Mercurio, U.; Tescione, D.; Scaramuzzino, F.

    2014-06-01

    In this paper, a numerical study has been carried out on skin delamination and skin-stringer debonding growth in a composite wing-box under compressive loading conditions. The adopted numerical models use the Virtual Crack Closure Technique to simulate the inter-laminar damage evolution and the numerical analyses have been performed by means of the FEM code ABAQUS and B2000++. The obtained numerical results have been assessed and compared each other in terms of delaminated area evolution, delamination growth initiation load and strain distributions. In order to investigate the effectiveness of the adopted numerical platforms in predicting the evolution of inter-laminar damages, comparisons with experimental data, in terms of load displacement curves and strains in the debonding area, have been also introduced.

  8. Damage evolution of yttria-stabilized zirconia induced by He irradiation

    SciTech Connect

    Yang, Tengfei; Huang, Xuejun; Gao, Yuan; Wang, Chenxu; Zhang, Yanwen; Xue, Jianming; Yan, Sha; Wang, Yugang

    2012-01-01

    The study presents an investigation of damage evolution of yttria-stabilized zirconia (YSZ) induced by irradiation of 100 keV He ions at room temperature as a function of fluence. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and atomic force microscopy (AFM) were used in order to study the nature and evolution of structural damage at different levels. Our study shows that various kinds of defects are formed with the increasing fluence. Firstly, at low fluences, from 1 1016 to 4 1016 cm 2, of which maximum values of displacement per atom (dpa) range from 0.29 to 1.17, an elastic strain which is attributed to the accumulation of irradiation-induced discrete point defects, is presented. Secondly, in the intermediate fluences ranging from 8 1016 to 1 1017 cm 2 with corresponding dpa varying from 2.33 to 2.91, a large drop of elastic strain occurs accompanied by presence of an intensive damage region, which is comprised by large and interacted defect clusters. Thirdly, at the two high fluences of 2 1017 and 4 1017 cm 2, of which dpa are 5.83 and 11.65 respectively, a great amount of ribbon-like He bubbles with granular structure and cracks are presented at the depth of maximum concentration of deposited He atoms. The structural damage evolution and the mechanism of formation of He bubbles are discussed.

  9. Critical evaluation of state evolution laws in rate and state friction: Fitting large velocity steps in simulated fault gouge with time-, slip-, and stress-dependent constitutive laws

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Pathikrit; Rubin, Allan M.; Bayart, Elsa; Savage, Heather M.; Marone, Chris

    2015-09-01

    The variations in the response of different state evolution laws to large velocity increases can dramatically alter the style of earthquake nucleation in numerical simulations. But most velocity step friction experiments do not drive the sliding surface far enough above steady state to probe this relevant portion of the parameter space. We try to address this by fitting 1-3 orders of magnitude velocity step data on simulated gouge using the most widely used state evolution laws. We consider the Dieterich (Aging) and Ruina (Slip) formulations along with a stress-dependent state evolution law recently proposed by Nagata et al. (2012). Our inversions confirm the results from smaller velocity step tests that the Aging law cannot explain the observed response and that the Slip law produces much better fits to the data. The stress-dependent Nagata law can produce fits identical to, and sometimes slightly better than, those produced by the Slip law using a sufficiently large value of an additional free parameter c that controls the stress dependence of state evolution. A Monte Carlo search of the parameter space confirms analytical results that velocity step data that are well represented by the Slip law can only impose a lower bound on acceptable values of c and that this lower bound increases with the size of the velocity step being fit. We find that our 1-3 orders of magnitude velocity steps on synthetic gouge impose this lower bound on c to be 10-100, significantly larger than the value of 2 obtained by Nagata et al. (2012) based on experiments on initially bare rock surfaces with generally smaller departures from steady state.

  10. Fatigue-damage evolution and damage-induced reduction of critical current of a Nb3Al superconducting composite

    NASA Astrophysics Data System (ADS)

    Ochiai, S.; Sekino, F.; Sawada, T.; Ohno, H.; Hojo, M.; Tanaka, M.; Okuda, H.; Koganeya, M.; Hayashi, K.; Yamada, Y.; Ayai, N.; Watanabe, K.

    2003-09-01

    We have studied the fatigue-damage mechanism of a Nb3Al superconducting composite at room temperature, and the influences of the fatigue damages introduced at room temperature on the critical current at 4.2 K and the residual strength at room temperature. The main (largest) fatigue crack arose first in the clad copper and then extended into the inner core with an increasing number of stress cycles. The cracking of the Nb3Al filaments in the core region occurred at a late stage (around 60-90% of the fatigue life). Once the fracture of the core occurred, it extended very quickly, resulting in a quick reduction in critical current and the residual strength with increasing stress cycles. Such a behaviour was accounted for by the crack growth calculated from the S-N curves (the relation of the maximum stress to the number of stress cycles at failure) combined with the Paris law. The size and distribution of the subcracks along the specimen length, and therefore the reduction in critical current of the region apart from the main crack, were dependent on the maximum stress level. The large subcracks causing fracture of the Nb3Al filaments were formed when the maximum stress was around 300-460 MPa, resulting in large reduction in critical current, but not when the maximum stress was outside such a stress range.

  11. Analysis of WWER-440 and PWR RPV welds surveillance data to compare irradiation damage evolution

    NASA Astrophysics Data System (ADS)

    Debarberis, L.; Acosta, B.; Zeman, A.; Sevini, F.; Ballesteros, A.; Kryukov, A.; Gillemot, F.; Brumovsky, M.

    2006-04-01

    It is known that for Russian-type and Western water reactor pressure vessel steels there is a similar degradation in mechanical properties during equivalent neutron irradiation. Available surveillance results from WWER and PWR vessels are used in this article to compare irradiation damage evolution for the different reactor pressure vessel welds. The analysis is done through the semi-mechanistic model for radiation embrittlement developed by JRC-IE. Consistency analysis with BWR vessel materials and model alloys has also been performed within this study. Globally the two families of studied materials follow similar trends regarding the evolution of irradiation damage. Moreover in the high fluence range typical of operation of WWER the radiation stability of these vessels is greater than the foreseen one for PWR.

  12. Modeling of delamination damage evolution in laminated composites subjected to low velocity impact

    NASA Technical Reports Server (NTRS)

    Lo, David C.; Allen, David H.

    1994-01-01

    This study examines the delamination evolution, under quasi-static conditions, of laminated polymeric composites with mechanically nonlinear resin rich interfaces. The constitutive behavior of the interface is represented by two models developed by Needleman and Tvegaard. These models assumed that the interfacial tractions, a function of only the interfacial displacement, will behave similarly to the interatomic forces generated during the interatomic seperation. The interface material's parameters control the load at which the delamination growth initiates and the final delamination size. A wide range of damage accumulation responses have been obtained by varying the model parameters. These results show that Tvergaard's model has been found to be better suited of the two models in predicting damage evolution for the configurations examined.

  13. The Influence of Grain Boundary Type upon Damage Evolution at Grain Boundary Interfaces

    SciTech Connect

    Perez-Bergquist, Alejandro G; Brandl, Christian; Escobedo, Juan P; Trujillo, Carl P; Cerreta, Ellen K; Gray III, George T; Germann, Timothy C

    2012-07-09

    In a prior work, it was found that grain boundary structure strongly influences damage evolution at grain boundaries in copper samples subjected to either shock compression or incipient spall. Here, several grain boundaries with different grain boundary structures, including a {Sigma}3 (10-1) boundary, are interrogated via conventional transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) to investigate the effects of atomic-scale structural differences on grain boundary strength and mobility. Boundaries are studied both before and after shock compression at a peak shock stress of 10 GPa. Results of the TEM and HRTEM work are used in conjunction with MD modeling to propose a model for shock-induced damage evolution at grain boundary interfaces that is dependent upon coincidence.

  14. Cumulative creep-fatigue damage evolution in an austenitic stainless steel

    NASA Technical Reports Server (NTRS)

    Mcgaw, Michael A.

    1992-01-01

    A model of cumulative creep-fatigue damage has been developed which is based on the use of damage curve equations to describe the evolution of creep-fatigue damage for four basic creep-fatigue cycle types. These cycle types correspond to the four fundamental cycles of the Strain Range Partitioning Life Prediction approach of Manson, Halford, and Hirschberg. A concept referred to as Damage Coupling is introduced to analytically account for the differences in the nature of the damage introduced by each cycle type. For application of this model, the cumulative creep-fatigue damage behavior of type 316 stainless steel at 816 C has been experimentally established for the two-level loading cases involving fatigue and creep-fatigue, in various permutations. The tests were conducted such that the lower life (high strain) cycling was applied first, for a controlled number of cycles, and the higher life (lower strain) cycling was conducted at the second level, to failure. The proposed model correlated the majority of the observed cumulative creep-fatigue data.

  15. Non-linear power law approach for spatial and temporal pattern analysis of salt marsh evolution

    NASA Astrophysics Data System (ADS)

    Taramelli, A.; Cornacchia, L.; Valentini, E.; Bozzeda, F.

    2013-11-01

    Many complex systems on the Earth surface show non-equilibrium fluctuations, often determining the spontaneous evolution towards a critical state. In this context salt marshes are characterized by complex patterns both in geomorphological and ecological features, which often appear to be strongly correlated. A striking feature in salt marshes is vegetation distribution, which can self-organize in patterns over time and space. Self-organized patchiness of vegetation can often give rise to power law relationships in the frequency distribution of patch sizes. In cases where the whole distribution does not follow a power law, the variance of scale in its tail may often be disregarded. To this end, the research aims at how changes in the main climatic and hydrodynamic variables may influence such non-linearity, and how numerical thresholds can describe this. Since it would be difficult to simultaneously monitor the presence and typology of vegetation and channel sinuosity through in situ data, and even harder to analyze them over medium to large time-space scales, remote sensing offers the ability to analyze the scale invariance of patchiness distributions. Here, we focus on a densely vegetated and channelized salt marsh (Scheldt estuary Belgium-the Netherlands) by means of the sub-pixel analysis on satellite images to calculate the non-linearity in the values of the power law exponents due to the variance of scale. The deviation from power laws represents stochastic conditions under climate drivers that can be hybridized on the basis of a fuzzy Bayesian generative algorithm. The results show that the hybrid approach is able to simulate the non-linearity inherent to the system and clearly show the existence of a link between the autocorrelation level of the target variable (i.e. size of vegetation patches), due to its self-organization properties, and the influence exerted on it by the external drivers (i.e. climate and hydrology). Considering the results of the stochastic model, high uncertainties can be associated to the short term climate influence on the saltmarshes, and the medium-long term spatial and temporal trends seem to be dominated by vegetation with its evolution in time and space. The evolution of vegetation patches (under power law) and channel sinuosity can then be used to forecast potential deviation from steady states in intertidal systems, taking into account the climatic and hydrological regimes.

  16. The second law of thermodynamics under unitary evolution and external operations

    SciTech Connect

    Ikeda, Tatsuhiko N.; Sakumichi, Naoyuki; Polkovnikov, Anatoli; Ueda, Masahito

    2015-03-15

    The von Neumann entropy cannot represent the thermodynamic entropy of equilibrium pure states in isolated quantum systems. The diagonal entropy, which is the Shannon entropy in the energy eigenbasis at each instant of time, is a natural generalization of the von Neumann entropy and applicable to equilibrium pure states. We show that the diagonal entropy is consistent with the second law of thermodynamics upon arbitrary external unitary operations. In terms of the diagonal entropy, thermodynamic irreversibility follows from the facts that quantum trajectories under unitary evolution are restricted by the Hamiltonian dynamics and that the external operation is performed without reference to the microscopic state of the system.

  17. The second law of thermodynamics under unitary evolution and external operations

    NASA Astrophysics Data System (ADS)

    Ikeda, Tatsuhiko N.; Sakumichi, Naoyuki; Polkovnikov, Anatoli; Ueda, Masahito

    2015-03-01

    The von Neumann entropy cannot represent the thermodynamic entropy of equilibrium pure states in isolated quantum systems. The diagonal entropy, which is the Shannon entropy in the energy eigenbasis at each instant of time, is a natural generalization of the von Neumann entropy and applicable to equilibrium pure states. We show that the diagonal entropy is consistent with the second law of thermodynamics upon arbitrary external unitary operations. In terms of the diagonal entropy, thermodynamic irreversibility follows from the facts that quantum trajectories under unitary evolution are restricted by the Hamiltonian dynamics and that the external operation is performed without reference to the microscopic state of the system.

  18. Scaling laws in laser-induced potassium dihydrogen phosphate crystal damage by nanosecond pulses at 3{omega}

    SciTech Connect

    Dyan, A.; Enguehard, F.; Lallich, S.; Piombini, H.; Duchateau, G.

    2008-06-15

    A model for the description of laser-induced damage in bulk potassium dihydrogen phosphate (KDP) by nanosecond laser pulses is addressed. It is based on the heating of nanometric plasma balls whose absorption efficiency is described through the Mie theory. The plasma optical indices are then evaluated within the Drude model framework. This modeling provides an evaluation of the scaling law exponent x linking the damage threshold laser pulse energy density F{sub c} to the pulse duration {tau} as F{sub c}={alpha}{tau}{sup x}, where {alpha} is a constant. The inverse problem for which the knowledge of experimental data allows one to determine physical parameters of the model is considered. The results suggest that the critical plasma density is reached in a time much shorter than the pulse duration. Information about the nature of defects responsible for the damage initiation is also provided.

  19. Unification of Small and Large Time Scales for Biological Evolution: Deviations from Power Law

    NASA Astrophysics Data System (ADS)

    Chowdhury, Debashish; Stauffer, Dietrich; Kunwar, Ambarish

    2003-02-01

    We develop a unified model that describes both “micro” and “macro” evolutions within a single theoretical framework. The ecosystem is described as a dynamic network; the population dynamics at each node of this network describes the “microevolution” over ecological time scales (i.e., birth, ageing, and natural death of individual organisms), while the appearance of new nodes, the slow changes of the links, and the disappearance of existing nodes accounts for the “macroevolution” over geological time scales (i.e., the origination, evolution, and extinction of species). In contrast to several earlier claims in the literature, we observe strong deviations from power law in the regime of long lifetimes.

  20. Damage evolution in GLARE fibre-metal laminate under repeated low-velocity impact tests

    NASA Astrophysics Data System (ADS)

    Morinière, Freddy D.; Alderliesten, René C.; Tooski, Mehdi Yarmohammad; Benedictus, Rinze

    2012-12-01

    An experimental study was performed on the repeated low-velocity impact behaviour of GLARE. Damage evolution in the material constituents was characterised with successive number of impacts. Records were correlated with visual inspection, ultrasound C-scan and chemical etching. The stiffness of the plate varied when cumulating the number of impacts. Damage accumulation was limited thanks to the synthesis of unidirectional composite and metal. The glass/epoxy plies with high elastic tensile strength could withstand several impacts before perforation despite delamination growth in the vicinity of the impacted area. The damage tolerant aluminium layers prevented the penetration of the projectile and avoided the expansion of delamination. This efficient mechanism preserved the structural integrity of GLARE until first aluminium cracking at the non-impacted side. Among the different failure modes, plate deformation absorbed most of the impact energy. The findings will support the development of a generic quasi-static analytical model and numerical methods.

  1. 32 CFR 536.50 - Determination of damages-applicable law.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., is prohibited. See DA Pam 27-162, paragraphs 2-56 and 3-4b. (f) Source of attorney's fees. Attorney's... damages—applicable law. (a) The Federal Tort Claims Act. The whole law of the place where the incident... the place of injury or death does not necessarily apply. Where there is a conflict between local...

  2. 32 CFR 536.50 - Determination of damages-applicable law.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., is prohibited. See DA Pam 27-162, paragraphs 2-56 and 3-4b. (f) Source of attorney's fees. Attorney's... damages—applicable law. (a) The Federal Tort Claims Act. The whole law of the place where the incident... the place of injury or death does not necessarily apply. Where there is a conflict between local...

  3. 32 CFR 536.50 - Determination of damages-applicable law.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., is prohibited. See DA Pam 27-162, paragraphs 2-56 and 3-4b. (f) Source of attorney's fees. Attorney's... damages—applicable law. (a) The Federal Tort Claims Act. The whole law of the place where the incident... the place of injury or death does not necessarily apply. Where there is a conflict between local...

  4. 26 CFR 1.162-22 - Treble damage payments under the antitrust laws.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Federal antitrust laws or enters a plea of guilty or nolo contendere to an indictment or information... account of such violation or any related violation of the Federal antitrust laws, provided such related... contesting a judgment of conviction, the taxpayer should file a protective claim for credit or refund...

  5. 26 CFR 1.162-22 - Treble damage payments under the antitrust laws.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Federal antitrust laws or enters a plea of guilty or nolo contendere to an indictment or information... account of such violation or any related violation of the Federal antitrust laws, provided such related... contesting a judgment of conviction, the taxpayer should file a protective claim for credit or refund...

  6. Intraspecific competition facilitates the evolution of tolerance to insect damage in the perennial plant Solanum carolinense.

    PubMed

    McNutt, David W; Halpern, Stacey L; Barrows, Kahaili; Underwood, Nora

    2012-12-01

    Tolerance to herbivory (the degree to which plants maintain fitness after damage) is a key component of plant defense, so understanding how natural selection and evolutionary constraints act on tolerance traits is important to general theories of plant-herbivore interactions. These factors may be affected by plant competition, which often interacts with damage to influence trait expression and fitness. However, few studies have manipulated competitor density to examine the evolutionary effects of competition on tolerance. In this study, we tested whether intraspecific competition affects four aspects of the evolution of tolerance to herbivory in the perennial plant Solanum carolinense: phenotypic expression, expression of genetic variation, the adaptive value of tolerance, and costs of tolerance. We manipulated insect damage and intraspecific competition for clonal lines of S. carolinense in a greenhouse experiment, and measured tolerance in terms of sexual and asexual fitness components. Compared to plants growing at low density, plants growing at high density had greater expression of and genetic variation in tolerance, and experienced greater fitness benefits from tolerance when damaged. Tolerance was not costly for plants growing at either density, and only plants growing at low density benefited from tolerance when undamaged, perhaps due to greater intrinsic growth rates of more tolerant genotypes. These results suggest that competition is likely to facilitate the evolution of tolerance in S. carolinense, and perhaps in other plants that regularly experience competition, while spatio-temporal variation in density may maintain genetic variation in tolerance. PMID:22684886

  7. Mathematical modeling of genome evolution: Where do the power laws come from

    NASA Astrophysics Data System (ADS)

    Koonin, Eugene

    2003-03-01

    Power law distributions appear in numerous biological, physical, social and other contexts, which appear to be fundamentally different. In biology, power laws have been claimed to describe the distributions of the connections of enzymes and metabolites in metabolic networks, the number of interaction partners of a given protein, the number of members in paralogous families, and other quantities. In network analysis, power laws imply evolution of the network with preferential attachment, i.e. a greater likelihood of nodes being added to pre-existing hubs. Exploration of different types of evolutionary models in an attempt to determine which of them lead to power law distributions has the potential of revealing non-trivial aspects of genome evolution. A simple model of evolution of the domain composition of proteomes was developed, with the following elementary processes: i) domain birth (duplication with divergence), ii) death (inactivation and/or deletion), and iii) innovation (emergence from non-coding or non-globular sequences or acquisition via horizontal gene transfer). This formalism can be described as a birth, death and innovation model (BDIM). The formulas for equilibrium frequencies of domain families of different size and the total number of families at equilibrium were derived for a general BDIM. All asymptotics of equilibrium frequencies of domain families possible for the given type of models were found and their appearance depending on model parameters was investigated. It was proved that the power law asymptotics appears if, and only if, the model is balanced, i.e., domain duplication (birth) and deletion (death) rates are asymptotically equal up to the second order. It was further proved that any power asymptotic with the degree not equal to -1 can appear only if the assumption of independence of the birth/death rates on the size of a domain family is rejected. Specific cases of BDIMs, namely simple, linear, polynomial and rational models, were explored in detail and the distributions of the equilibrium frequencies of domain families of different size were determined for each case. The BDIM formalism was applied to the analysis of the domain family size distributions in prokaryotic and eukaryotic proteomes and an excellent fit was observed between these empirical data and a particular form of the model, the second-order balanced linear BDIM. Calculation of the parameters of these models suggests surprisingly high innovation rates, comparable to the total domain birth (duplication) and death (elimination) rates, particularly for prokaryotic genomes. Thus, a straightforward model of genome evolution, which does not explicitly include selection, seems to be sufficient to explain the observed distributions of domain family sizes, in which power laws appear as asymptotic. However, for the model to be compatible with the data, there has to be a precise balance between domain birth, death and innovation rates, and this is likely to be maintained by selection. The developed approach is oriented at a mathematical description of evolution of domain composition of proteomes, but a simple reformulation could be applied to models of other evolving networks with preferential attachment.

  8. 26 CFR 1.162-22 - Treble damage payments under the antitrust laws.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... damages entered against the taxpayer under section 4 of the Clayton Act (15 U.S.C. 15), as amended, on... section shall include the Federal acts enumerated in paragraph (1) of section 1 of the Clayton Act (15 U.S... $300,000 in treble damages under section 4 of the Clayton Act. Z Co.'s complaint alleged that...

  9. 26 CFR 1.162-22 - Treble damage payments under the antitrust laws.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... damages entered against the taxpayer under section 4 of the Clayton Act (15 U.S.C. 15), as amended, on... section shall include the Federal acts enumerated in paragraph (1) of section 1 of the Clayton Act (15 U.S... $300,000 in treble damages under section 4 of the Clayton Act. Z Co.'s complaint alleged that...

  10. Laws of Conservation as Related to Brain Growth, Aging, and Evolution: Symmetry of the Minicolumn

    PubMed Central

    Casanova, Manuel F.; El-Baz, Ayman; Switala, Andrew

    2011-01-01

    Development, aging, and evolution offer different time scales regarding possible anatomical transformations of the brain. This article expands on the perspective that the cerebral cortex exhibits a modular architecture with invariant properties in regards to these time scales. These properties arise from morphometric relations of the ontogenetic minicolumn as expressed in Noether’s first theorem, i.e., that for each continuous symmetry there is a conserved quantity. Whenever minicolumnar symmetry is disturbed by either developmental or aging processes the principle of least action limits the scope of morphometric alterations. Alternatively, local and global divergences from these laws apply to acquired processes when the system is no longer isolated from its environment. The underlying precepts to these physical laws can be expressed in terms of mathematical equations that are conservative of quantity. Invariant properties of the brain include the rotational symmetry of minicolumns, a scaling proportion or “even expansion” between pyramidal cells and core minicolumnar size, and the translation of neuronal elements from the main axis of the minicolumn. It is our belief that a significant portion of the architectural complexity of the cerebral cortex, its response to injury, and its evolutionary transformation, can all be captured by a small set of basic physical laws dictated by the symmetry of minicolumns. The putative preservations of parameters related to the symmetry of the minicolumn suggest that the development and final organization of the cortex follows a deterministic process. PMID:22207838

  11. Laws of conservation as related to brain growth, aging, and evolution: symmetry of the minicolumn.

    PubMed

    Casanova, Manuel F; El-Baz, Ayman; Switala, Andrew

    2011-01-01

    Development, aging, and evolution offer different time scales regarding possible anatomical transformations of the brain. This article expands on the perspective that the cerebral cortex exhibits a modular architecture with invariant properties in regards to these time scales. These properties arise from morphometric relations of the ontogenetic minicolumn as expressed in Noether's first theorem, i.e., that for each continuous symmetry there is a conserved quantity. Whenever minicolumnar symmetry is disturbed by either developmental or aging processes the principle of least action limits the scope of morphometric alterations. Alternatively, local and global divergences from these laws apply to acquired processes when the system is no longer isolated from its environment. The underlying precepts to these physical laws can be expressed in terms of mathematical equations that are conservative of quantity. Invariant properties of the brain include the rotational symmetry of minicolumns, a scaling proportion or "even expansion" between pyramidal cells and core minicolumnar size, and the translation of neuronal elements from the main axis of the minicolumn. It is our belief that a significant portion of the architectural complexity of the cerebral cortex, its response to injury, and its evolutionary transformation, can all be captured by a small set of basic physical laws dictated by the symmetry of minicolumns. The putative preservations of parameters related to the symmetry of the minicolumn suggest that the development and final organization of the cortex follows a deterministic process. PMID:22207838

  12. Dynamic damage evolution in aluminum as a model system for understanding FCC materials in extreme conditions

    NASA Astrophysics Data System (ADS)

    Sanchez, Nathaniel Jonathon

    Materials play a key role in many emerging technologies. Future technologies in the energy and defense sectors will place huge demands on material performance with respect to stress, strain, temperature, and pressure. These applications require that the response of materials on dynamic (microsecond) time scales be predictable and controllable. Hence, the goal of this research project was to study the extreme environment of shock loaded damage evolution in aluminum as a model system for understanding dynamic response of FCC metals in these environments. Phase one utilized plate impact experiments to study the influence of spatial effects (in the form of microstructural defect distributions) on the dynamic damage evolution process. Samples were soft recovered for shot analysis and comparison to real time laser velocimetry. Results revealed that the length scale of defects controls the failure mechanisms of the microstructure; suggesting defect density and the spatial distribution of defects are critical factors in the deformation process in extreme environments. Phase two studied the influence of kinetic effects (in the form of dynamic tensile loading rate) to reveal time dependence on the dynamic deformation process. Results concluded damage nucleation and growth rates are highly time dependent and can be overdriven as higher tensile loading rates result in extremely short time durations. It was shown that laser velocimetry provides an adequate means for understanding the dynamic damage evolution process when soft recovery of the sample is unavailable. This was shown by comparing laser velocimetry results with data obtained from optical analysis on recovered specimens. The methodology here provides a means to systematically study materials of interest in extreme conditions and provides a pathway for obtaining the relevant physics needed for model development leading to a predictive capability.

  13. A Numerical Method for Simulating the Microscopic Damage Evolution in Composites Under Uniaxial Transverse Tension

    NASA Astrophysics Data System (ADS)

    Zhi, Jie; Zhao, Libin; Zhang, Jianyu; Liu, Zhanli

    2015-08-01

    In this paper, a new numerical method that combines a surface-based cohesive model and extended finite element method (XFEM) without predefining the crack paths is presented to simulate the microscopic damage evolution in composites under uniaxial transverse tension. The proposed method is verified to accurately capture the crack kinking into the matrix after fiber/matrix debonding. A statistical representative volume element (SRVE) under periodic boundary conditions is used to approximate the microstructure of the composites. The interface parameters of the cohesive models are investigated, in which the initial interface stiffness has a great effect on the predictions of the fiber/matrix debonding. The detailed debonding states of SRVE with strong and weak interfaces are compared based on the surface-based and element-based cohesive models. The mechanism of damage in composites under transverse tension is described as the appearance of the interface cracks and their induced matrix micro-cracking, both of which coalesce into transversal macro-cracks. Good agreement is found between the predictions of the model and the in situ experimental observations, demonstrating the efficiency of the presented model for simulating the microscopic damage evolution in composites.

  14. Process-induced damage evolution and management in resin transfer molding of composite panels

    NASA Astrophysics Data System (ADS)

    Kuan, Yean-Der

    2000-10-01

    Woven fiber composites made by resin transfer molding process are currently used as the primary and secondary load bearing structures in automotive and aircraft industries. A variety of defects could be evolved during the injection stage and the curing stage of the process. Improper injection conditions or unsound tool design would result in process induced damage in the form of dry spots, incomplete filling, or displacement of the fiber. In the curing stage, the process parameters of heating and cooling rates, and the temperature level at each element of the curing cycle have direct effects on the development of internal residual stresses, and shape distortion due to warpage. The work in this dissertation aims at developing numerical models to predict, characterize, and minimize process-induced damage during both the injection stage and curing stage in RTM process for woven-fiber composites. A control volume technique based on the finite difference method is used to characterize the flow behavior in resin transfer molding (RTM) of composite structures. Resin flow through fiber mats is modeled as a two-phase flow through porous media. Experimental results on flow behavior of EPON 826 epoxy resin into irregular mold cavity with fiberglass mats agree well with the present numerical simulation. Parametric analysis of several case studies using developed model illustrates the effectiveness of the flow model in investigating the flow pattern, mold filling time, dry spots formulation, and pressure distribution inside the mold. A numerical model describing the evolution of process-induced damage during curing in molded composite panels was developed. The effects of thermo-mechanical and thermo-chemical responses of the material on the evolution of damage during resin transfer molding of the panels are quantified. The developed numerical model in conjunction with an optimization module based on Simulated Annealing (SA) scheme form a useful tool for conducting a parametric design analysis for characterization and management of process-induced damage in composite panels. Experimental investigation of resin transfer molding of composite panels made of epoxy resin (EPON 826) and eight-harness graphite fiber mats, indicates that low cure temperature, moderate heating rate and high rate of cooling after cure would minimize damage during curing. Furthermore the experimental measurements are in agreement with the degree of damage predicted by the numerical models and hence verifying the effectiveness of these models. The models and methods developed in the present work are of broader applicability to process design and optimization of resin transfer molding of composite structures.

  15. Damage Evolution in GaN Under MeV Heavy Ion Implantation

    SciTech Connect

    Gao, Yuan; Xue, Jianming; Zhang, Dongzheng; Wang, Zilong; Lan, Chune; Yan, Sha; Wang, Yugang; Xu, Fujun; Shen, Bo; Zhang, Yanwen

    2009-10-22

    Damage evaluation processes in patterned GaN implanted by 3 MeV Au2+ ions were investigated as function of ion fluences and annealing temperatures. Surface swelling was observed by using AFM and the results showed that the swelling height depends on ion fluence and annealing temperature. A four-stage of implantatation-induced damage evolution, including point defects, defect clustering, disordering or amorphization and even decomposition, was found and was contributed to defect formation, accumulation and N bubble formation induced at different level of dpa. Crater-like holes were observed on the surface of GaN implanted at the ion fluence of 2×1016 cm-2, and it is considered as an evidence of N loss and broken bubbles formed during implantation.

  16. Simulation of Damage Evolution in Composites: A Phase-field Model

    SciTech Connect

    Biner, S.B.; Hu, Shenyang Y.

    2009-04-01

    First, a phase-field model for elastic-plastic solids obeying von Mises yield criterion will be described. Then, this phase-field model will be extended to simulate the damage evolution due to nucleation and growth of voids in ductile matrix for discontinuously reinforced composites. The role of reinforcement morphology and the modulus effects leading to final failure all included in the simulations in an effort to make a parametric investigation. The advantages and disadvantages of such phase-field modeling approach in comparison to well established other continuum methods will be elucidated.

  17. Damage evolution and residual stresses in plasma-sprayed zirconia thermal barrier coatings.

    SciTech Connect

    Singh, J. P.

    1999-02-03

    Air-plasma-sprayed zirconia thermal barrier coatings were subjected to thermal cycling and residual stress evolution in thermally grown oxide scale was studied by micro- and macro-ruby fluorescence spectroscopy. The macro approach reveals that compressive stress in the oxide scale increases with increasing number of thermal cycles (and thus increasing scale thickness), reaching a value of 1.8 GPa at a scale thickness of 3-4 {micro}m (80 cycles). Micro-ruby fluorescence spectroscopy indicates that protrusions of the zirconia top coat into the bond coat act as localized areas of high stress concentration, leading to damage initiation during thermal cycling.

  18. Effect of Temperature on Damage Evolution of Cr25Ni35Nb Alloy Subjected to Combined Mechanical and Environmental Degradation

    NASA Astrophysics Data System (ADS)

    Shen, Limin; Liu, Huansheng; Gong, Jianming; Geng, Luyang

    2015-07-01

    Due to combined mechanical and environmental degradation, i.e. coupled creep and carburization, Cr25Ni35Nb alloy often fails prior to the expected design life. In the present paper, based on the continuum damage mechanics, the constitutive model of coupled multi-damage factors for computing the damage evolution of Cr25Ni35Nb alloy was proposed. The damage prediction was carried out by using finite element method based on ABAQUS code. And then damage evolution processes at different operating temperatures (950 °C and 1050 °C) were simulated and the effect of service temperature on the damage evolution was discussed. The results showed that the rate of damage increased obviously with operating temperature increasing. The location with maximum damage is along the inner surface of tube, which implies that fracture begins along the inner surface of tube under the action of coupled creep and carburization damage and this is coincident with the actual observation of the failure of furnace tube.

  19. 26 CFR 1.162-22 - Treble damage payments under the antitrust laws.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... criminal conspiracy between X Co. and Y Co. forced Z Co. to pay excessive prices for electrical... example (1) except that Z Co.'s claim for treble damages was based on a conspiracy to fix and maintain... by the defendants' fraudulent concealment of their conspiracy. Since the United States has...

  20. Detection of structural damage in multiwire cables by monitoring the entropy evolution of wavelet coefficients

    NASA Astrophysics Data System (ADS)

    Ibáñez, Flor; Baltazar, Arturo; Mijarez, Rito; Aranda, Jorge

    2015-03-01

    Multiwire cables are widely used in important civil structures. Since they are exposed to several dynamic and static loads, their structural health can be compromised. The cables can also be submitted to mechanical contact, tension and energy propagation in addition to changes in size and material within their wires. Due to the critical role played by multiwire cables, it is necessary to develop a non-destructive health monitoring method to maintain their structure and proper performance. Ultrasonic inspection using guided waves is a promising non-destructive damage monitoring technique for rods, single wires and multiwire cables. The propagated guided waves are composed by an infinite number of vibrational modes making their analysis difficult. In this work, an entropy-based method to identify small changes in non-stationary signals is proposed. A system to capture and post-process acoustic signals is implemented. The Discrete Wavelet Transform (DWT) is computed in order to obtain the reconstructed wavelet coefficients of the signals and to analyze the energy at different scales. The feasibility of using the concept of entropy evolution of non-stationary signals to detect damage in multiwire cables is evaluated. The results show that there is a high correlation between the entropy value and damage level of the cable. The proposed method has low sensitivity to noise and reduces the computational complexity found in a typical time-frequency analysis.

  1. An incremental-iterative method for modeling damage evolution in voxel-based microstructure models

    NASA Astrophysics Data System (ADS)

    Zhu, Qi-Zhi; Yvonnet, Julien

    2015-02-01

    Numerical methods motivated by rapid advances in image processing techniques have been intensively developed during recent years and increasingly applied to simulate heterogeneous materials with complex microstructure. The present work aims at elaborating an incremental-iterative numerical method for voxel-based modeling of damage evolution in quasi-brittle microstructures. The iterative scheme based on the Lippmann-Schwinger equation in the real space domain (Yvonnet, in Int J Numer Methods Eng 92:178-205, 2012) is first cast into an incremental form so as to implement nonlinear material models efficiently. In the proposed scheme, local strain increments at material grid points are computed iteratively by a mapping operation through a transformation array, while local stresses are determined using a constitutive model that accounts for material degradation by damage. For validation, benchmark studies and numerical simulations using microtomographic data of concrete are performed. For each test, numerical predictions by the incremental-iterative scheme and the finite element method, respectively, are presented and compared for both global responses and local damage distributions. It is emphasized that the proposed incremental-iterative formulation can be straightforwardly applied in the framework of other Lippmann-Schwinger equation-based schemes, like the fast Fourier transform method.

  2. Detection of damage in multiwire cables based on wavelet entropy evolution

    NASA Astrophysics Data System (ADS)

    Ibáñez, Flor; Baltazar, Arturo; Mijarez, Rito

    2015-08-01

    Multiwire cables are widely used in important engineering structures. Since they are exposed to several dynamic and static loads as well as detrimental environmental conditions, their structural health can be compromised. Due to the critical role played by multiwire cables, it is necessary to develop a non-destructive health monitoring method to maintain their structure and proper performance. Ultrasonic inspection using guided waves is a promising non-destructive damage monitoring technique for rods, single and multiwire cables. However, the propagated guided waves are composed of an infinite number of dispersive vibrational modes making their analysis difficult. In this work, an entropy-based method to identify small changes in non-stationary signals is proposed. An experimental system to capture and post-process acoustic signals is implemented. The discrete wavelet transform is computed in order to obtain the reconstructed wavelet coefficients of the signals and to analyze the energy at different scales. The use of the concept of entropy evolution of non-stationary signals to detect damage in multiwire cables is evaluated. The results show that there is a correlation between the entropy value and level of damage of the cable including breaking of single wires and change in the mechanical contact conditions among the wires. It is found that the studied method has low sensitivity to signal noise and can reduce the computational complexity encountered in a typical time-frequency analysis.

  3. Jurisdiction and applicable law in cases of damage from space in Europe—The advent of the most suitable choice—Rome II

    NASA Astrophysics Data System (ADS)

    Smith, Lesley Jane; Doldirina, Catherine

    2010-01-01

    Liability for space activities is a much discussed subject and the advent of commercial space operations has only added to its importance. Articles VI and VII Outer Space Treaty, together with Articles II and III Liability Convention, remain the main entry level for state liability for damage arising from private space activities. Few space-faring nations have introduced national space statutes that include a flow down of their international obligations. The European Union (EU) Regulation on the law applicable to non-contractual obligations—hereinafter Rome II Regulation—could harbour developments for liability law in the context of damage resulting from space operations. Space activities were not the main focus of the Regulation but may well turn out to be an interesting spin-off. The Regulation prescribes general rules that will determine the law applicable to damage scenarios where more than one legal system applies. It is important for trans-national tort cases in that it does not limit the rules of applicable law to EU Member States only. This paper focuses on the common rules applicable to damage actions based on torts or other non-contractual obligations as they apply to damage caused by space activities. After an assessment of the relevant international and national law norms, the impact of the Rome II Regulation will be addressed.

  4. Regional Distribution and Evolution of Gray Matter Damage in Different Populations of Multiple Sclerosis Patients

    PubMed Central

    Calabrese, Massimiliano; Reynolds, Richard; Magliozzi, Roberta; Castellaro, Marco; Morra, Aldo; Scalfari, Antonio; Farina, Gabriele; Romualdi, Chiara; Gajofatto, Alberto; Pitteri, Marco; Benedetti, Maria Donata; Monaco, Salvatore

    2015-01-01

    Background Both gray-matter (GM) atrophy and lesions occur from the earliest stages of Multiple Sclerosis (MS) and are one of the major determinants of long-term clinical outcomes. Nevertheless, the relationship between focal and diffuse GM damage has not been clarified yet. Here we investigate the regional distribution and temporal evolution of cortical thinning and how it is influenced by the local appearance of new GM lesions at different stages of the disease in different populations of MS patients. Methods We studied twenty MS patients with clinically isolated syndrome (CIS), 27 with early relapsing-remitting MS (RRMS, disease duration <5 years), 29 with late RRMS (disease duration ≥ 5 years) and 20 with secondary-progressive MS (SPMS). The distribution and evolution of regional cortical thickness and GM lesions were assessed during 5-year follow-up. Results The results showed that new lesions appeared more frequently in hippocampus and parahippocampal gyri (9.1%), insula (8.9%), cingulate cortex (8.3%), superior frontal gyrus (8.1%), and cerebellum (6.5%). The aforementioned regions showed the greatest reduction in thickness/volume, although (several) differences were observed across subgroups. The correlation between the appearance of new cortical lesions and cortical thinning was stronger in CIS (r2 = 50.0, p<0.001) and in early RRMS (r2 = 52.3, p<0.001), compared to late RRMS (r2 = 25.5, p<0.001) and SPMS (r2 = 6.3, p = 0.133). Conclusions We conclude that GM atrophy and lesions appear to be different signatures of cortical disease in MS having in common overlapping spatio-temporal distribution patterns. However, the correlation between focal and diffuse damage is only moderate and more evident in the early phase of the disease. PMID:26267665

  5. Microstructural Observation and Simulation of Micro Damage Evolution of Ternary Polypropylene Blend with Ethylene-Propylene-Rubber (EPR) and Talc

    NASA Astrophysics Data System (ADS)

    Mae, Hiroyuki; Omiya, Masaki; Kishimoto, Kikuo

    An attempt has been made to study the microstructural deformation and micro damage evolution process in the thermoplastic polypropylene (PP) blended with the ethylene-propylene rubber (EPR) and talc. The in situ observation is conducted during uniaxially stretching within TEM step by step to investigate the deformation events depending on the elongation of samples. In addition, the microstructural deformation and damage evolution process were simulated by coarse-grained molecular dynamics (MD). The experimental result shows that the micro damage initiates at the interface between PP matrix and talc particle. Then, the micro void is generated there, leading to the fibrils of the PP matrix and EPR particles. The similar trend of the micro damage evolution process is obtained by MD simulation. Finally, the effects of the interfacial strength of PP-EPR and PP-talc on the microstructural damage evolution and macroscopic mechanical properties are investigated. It is indicated that increasing the interfacial strength between PP-EPR is more effective for improving the stiffness and the maximum stress, compared to the PP-talc interfacial strength. In addition, to enhance the material ductility, it is important to increase the interfacial strength of PP-EPR.

  6. The evolution and definition of the concept of 'automatism' in Canadian case law.

    PubMed

    Jang, D; Coles, E M

    1995-01-01

    Legal and psychological perspectives are blended in a review of the evolution and definition of the legal concept of 'automatism'. Despite the oft-cited, succinct definitions such as those provided by Bowlby JA in R v Kasperek [1951] 101 CCC 375, and by Mr Justice Lacourciere (as he then was) in R v K [1971] 3 CCC (2d) 84 which emphasize a lack of consciousness, case law has shown a tendency to emphasize a lack of volitional control. It has also insisted that such a deficit be primarily brought about by an external factor over which the accused either had no control or, if they had control, of which effects they lacked knowledge. Two noticeable omissions are identified. One is a lack of a logical evaluation of expert testimony in terms of the complexity of the criminal acts that have been claimed to accompany an impoverished mental state. The other is the failure to recognize the mental chemistry of the presence of multiple conditions in the same person at the same time. An overriding concern has been protection of the public, and decisions in a number of cases can be regarded as attempts to ensure that this is achieved before permitting the unqualified acquittal that automatism would bring. PMID:8524004

  7. Prediction of damage evolution in continuous fiber metal matrix composites subjected to fatigue loading

    SciTech Connect

    Allen, D.; Helms, K.; Lagoudas, D.

    1995-08-01

    A life prediction model is being developed by the authors for application to metal matrix composites (MMC`s). The systems under study are continuous silicon carbide fibers imbedded in titanium matrix. The model utilizes a computationally based framework based on thermodynamics and continuum mechanics, and accounts for matrix inelasticity, damage evolution, and environmental degradation due to oxidation. The computational model utilizes the finite element method, and an evolutionary analysis of a unit cell is accomplished via a time stepping algorithm. The computational scheme accounts for damage growth such as fiber-matrix debonding, surface cracking, and matrix cracking via the inclusion of cohesive zone elements in the unit cell. These elements are located based on experimental evidence also obtained by the authors. The current paper outlines the formulation utilized by the authors to solve this problem, and recent results are discussed. Specifically, results are given for a four-ply unidirectional composite subjected to cyclic fatigue loading at 650{degrees}C both in air and inert gas. The effects of oxidation on the life of the composite are predicted with the model, and the results are compared to limited experimental results.

  8. PCA algorithm for detection, localisation and evolution of damages in gearbox bearings

    NASA Astrophysics Data System (ADS)

    Pirra, M.; Gandino, E.; Torri, A.; Garibaldi, L.; Machorro-López, J. M.

    2011-07-01

    A fundamental aspect when dealing with rolling element bearings, which often represent a key component in rotating machineries, consists in correctly identifying a degraded behaviour of a bearing with a reasonable level of confidence. This is one of the main requirements a health and usage monitoring system (HUMS) should have. This paper introduces a monitoring technique for the diagnosis of bearing faults based on Principal Component Analysis (PCA). This method overcomes the problem of acquiring data under different environmental conditions (hardly biasing the data) and allows accurate damage recognition, also assuring a rather low number of False Alarms (FA). In addition, a novel criterion is proposed in order to isolate the area in which the faulty bearing stands. Another useful feature of this PCA-based method concerns the capability to observe an increasing trend in the evolution of bearing degradation. The described technique is tested on an industrial rig (designed by Avio S.p.A.), consisting of a full size aeroengine gearbox. Healthy and variously damaged bearings, such as with an inner or rolling element fault, are set up and vibration signals are collected and processed in order to properly detect a fault. Finally, data collected from a test rig assembled by the Dynamics & Identification Research Group (DIRG) are used to demonstrate that the proposed method is able to correctly detect and to classify different levels of the same type of fault and also to localise it.

  9. Relating damage evolution of concrete cooled to cryogenic temperatures to permeability

    NASA Astrophysics Data System (ADS)

    Kogbara, Reginald B.; Iyengar, Srinath R.; Grasley, Zachary C.; Rahman, Syeda; Masad, Eyad A.; Zollinger, Dan G.

    2014-11-01

    Typically, 9% Ni steel is used for primary containment of liquefied natural gas (LNG). Utilization of concrete in place of 9% Ni steel for primary containment would lead to significant cost savings. Hence, this study investigates changes in the microstructure of concrete due to cryogenic freezing that would affect its relevant engineering properties for containment. The study also evaluates the effect of aggregate type on the damage potential of concrete subjected to cryogenic freezing. The aim is to investigate design methodologies to produce damage-resistant cryogenic concrete. The study employed four concrete mixture designs involving river sand as fine aggregate, and coarse aggregates with different coefficient of thermal expansion (CTE) values. Specifically, the coarse aggregates were limestone, sandstone, trap rock and lightweight aggregate. Concrete cubes were cured under water for at least 28 days and thereafter frozen from ambient (20 °C) to cryogenic temperature (-165 °C). Acoustic emission (AE) sensors were placed on the concrete cubes during freezing. X-ray computed tomography (XRCT) was employed to study the microstructure of concrete cores, before and after cryogenic freezing. The impact of the microstructural evolution thus obtained from AE and XRCT on relevant engineering properties was determined via water and chloride permeability tests. Microcrack propagation determined from AE correlated with changes in permeability. There were no observable cracks in majority of the concrete mixtures after freezing. This implies that microcracks detected via AE and increased permeability was very well distributed and smaller than the XRCT's resolution. Damage (microcracking) resistance of the concrete with different aggregates was in the order limestone ⩾ trap rock ≫ lightweight aggregate ⩾ sandstone.

  10. Proposed damage evolution model for large-scale finite element modeling of the dual coolant US-ITER TBM

    NASA Astrophysics Data System (ADS)

    Sharafat, S.; El-Awady, J.; Liu, S.; Diegele, E.; Ghoniem, N. M.

    2007-08-01

    Large-scale finite element modeling (FEM) of the US Dual Coolant Lead Lithium ITER Test Blanket Module including damage evolution is under development. A comprehensive rate-theory based radiation damage creep deformation code was integrated with the ABACUS FEM code. The advantage of this approach is that time-dependent in-reactor deformations and radiation damage can now be directly coupled with 'material properties' of FEM analyses. The coupled FEM-Creep damage model successfully simulated the simultaneous microstructure and stress evolution in small tensile test-bar structures. Applying the integrated Creep/FEM code to large structures is still computationally prohibitive. Instead, for thermo-structural analysis of the DCLL TBM structure the integrated FEM-creep damage model was used to develop true stress-strain behavior of F82H ferritic steel. Based on this integrated damage evolution-FEM approach it is proposed to use large-scale FEM analysis to identify and isolate critical stress areas for follow up analysis using detailed and fully integrated creep-FEM approach.

  11. Evolution of elastic wave speed during shear-induced damage and healing within laboratory fault zones

    NASA Astrophysics Data System (ADS)

    Kaproth, Bryan M.; Marone, Chris

    2014-06-01

    Earthquake faults fail and restrengthen repeatedly during the seismic cycle. Faults restrengthen via a set of processes known collectively as fault healing, which is well documented in the laboratory but less well understood in tectonic fault zones. Recent observations of fault zone wave speed following earthquakes suggest opportunities to connect laboratory and field observations of fault healing. However, existing laboratory data lack detail necessary to identify specific processes linking elastic wave speed to fault damage and healing. Here we document changes in elastic properties during laboratory seismic cycles, simulated via periods of nonshear and quasistatic fault slip. Experiments were conducted on brine-saturated halite under conditions favoring pressure solution, analogous to healing processes within and at the base of the seismogenic zone. We find that elastic wave speed (V) and amplitude (A) correlate with porosity. For each percent of porosity lost during compaction, VP increases by ~3%, VS by ~2%, AP by ~10%, and AS by ~7%. Moreover, V and A decrease with granular dilation during fault slip. With increasing shear strain, fabric formation dominates the ultrasonic signals. We find that fault strength depends on fault porosity, making VP and VS potential proxies for fault strength evolution. Our data show that a 1% change in VP or VS results in a friction increase of 0.01 or 0.02, respectively. Within natural fault zones, advances in monitoring elastic wave speed may provide critical information on the evolution of fault strength and seismic hazard throughout the seismic cycle.

  12. Modeling the long-term evolution of the primary damage in ferritic alloys using coarse-grained methods

    NASA Astrophysics Data System (ADS)

    Becquart, C. S.; Barbu, A.; Bocquet, J. L.; Caturla, M. J.; Domain, C.; Fu, C.-C.; Golubov, S. I.; Hou, M.; Malerba, L.; Ortiz, C. J.; Souidi, A.; Stoller, R. E.

    2010-11-01

    Knowledge of the long-term evolution of the microstructure after introduction of primary damage is an essential ingredient in understanding mechanical property changes that occur during irradiation. Within the European integrated project "PERFECT," different techniques have been developed or improved to model microstructure evolution of Fe alloys under irradiation. This review paper aims to present the current state of the art of these techniques, as developed in the project, as well as the main results obtained.

  13. Damage Evolution in Composite Materials and Sandwich Structures Under Impulse Loading

    NASA Astrophysics Data System (ADS)

    Silva, Michael Lee

    Damage evolution in composite materials is a rather complex phenomenon. There are numerous failure modes in composite materials stemming from the interaction of the various constituent materials and the particular loading conditions. This thesis is concerned with investigating damage evolution in sandwich structures under repeated transient loading conditions associated with impulse loading due to hull slamming of high-speed marine craft. To fully understand the complex stress interactions, a full field technique to reveal stress or strain is required. Several full field techniques exist but are limited to materials with particular optical properties. A full field technique applicable to most materials is known as thermoelastic stress analysis (TSA) and reveals the variation in sum of principal stresses of a cyclically loaded sample by correlating the stresses to a small temperature change occurring at the loading frequency. Digital image correlation (DIC) is another noncontact full field technique that reveals the deformation field by tracking the motion of subsets of a random speckle pattern during the loading cycles. A novel experimental technique to aid in the study of damage progression that combines TSA and DIC simultaneously utilizing a single infrared camera is presented in this thesis. A technique to reliably perform DIC with an infrared (IR) camera is developed utilizing variable emissivity paint. The thermal data can then be corrected for rigid-body motion and deformation such that each pixel represents the same material point in all frames. TSA is then performed on this corrected data, reducing motion blur and increasing accuracy. This combined method with a single infrared camera has several advantages, including a straightforward experimental setup without the need to correct for geometric effects of two spatially separate cameras. Additionally, there is no need for external lighting in TSA as the measured electromagnetic radiation is emitted by the sample's thermal fields. The particular stress resolution of TSA will depend on properties of the material of interest but the noise floor for the temperature variation is universal to the camera utilized. For the camera system in this thesis, the noise floor was found to be fairly frequency independent with a magnitude of 0.01 °C, giving the minimum measurable stress for 2024 aluminum alloy of 3.6 MPa and for Nylon of 0.84 MPa. The average displacement range found during a static DIC test with IR images was 0.1 pixels. The maximum displacement variation at 1 Hz was 0.018 pixels. The average variation in strain at 1 Hz was 25 microstrain comparable to traditional DIC measurements in the visible optical regime. The combined TSA-DIC method in IR was validated with several benchmark example problems including plate structures with holes, cracks, and bimaterials. The validated technique was applied to foam-core sandwich composite beams under repeated simulated wave slamming loading. There are numerous failure modes in sandwich composite materials and the full field stress and strain from TSA and DIC, respectively, allow for improved failure analysis and prediction. Understanding damage in sandwich structures under impulse loading is a complex open area of research and the combined TSA-DIC method provides further insight into the failure process.

  14. Information on the evolution of severe LWR fuel element damage obtained in the CORA program

    NASA Astrophysics Data System (ADS)

    Schanz, G.; Hagen, S.; Hofmann, P.; Schumacher, G.; Sepold, L.

    1992-06-01

    In the CORA program a series of out-of-pile experiments on LWR severe accidental situations is being performed, in which test bundles of LWR typical components and arrangements (PWR, BWR) are exposed to temperature transients up to about 2400°C under flowing steam. The individual features of the facility, the test conduct, and the evaluation will be presented. In the frame of the international cooperation in severe fuel damage (SFD) programs the CORA tests are contributing confirmatory and complementary informations to the results from the limited number of in-pile tests. The identification of basic phenomena of the fuel element destruction, observed as a function of temperature, is supported by separate-effects test results. Most important mechanisms are the steam oxidation of the Zircaloy cladding, which determines the temperature escalation, the chemical interaction between UO 2 fuel and cladding, which dominates fuel liquefaction, relocation and resulting blockage formation, as well as chemical interactions with Inconel spacer grids and absorber units ((Ag, In, Cd) alloy or B 4C), which are leading to extensive low-temperature melt formation around 1200°C. Interrelations between those basic phenomena, resulting for example in cladding deformation ("flowering") and the dramatic hydrogen formation in response to the fast cooling of a hot bundle by cold water ("quenching") are determining the evolution paths of fuel element destruction, which are to be identified. A further important task is the abstraction from mechanistic and microstructural details in order to get a rough classification of damage regimes (temperature and extent), a practicable analytical treatment of the materials behaviour, and a basis for decisions in accident mitigation and management procedures.

  15. Fatigue crack initiation and damage evolution of unnotched titanium matrix composites

    NASA Astrophysics Data System (ADS)

    Her, Yung-Chiun

    Fatigue crack initiation, multiplication, matrix crack density evolution, and stiffness reduction of several unnotched SCS-6 silicon carbide fiber-reinforced titanium and titanium aluminide matrix composites have been investigated experimentally and analytically. The effects of the thickness of the interfacial reaction layer and fiber coating on fatigue crack initiation life, crack growth rate, and fatigue damage evolution of the composites were examined. Growth behavior of small fatigue cracks in TMCs was also studied carefully. It was found that fatigue crack initiation and multiplication of TMCs are strongly influenced by the thickness of the interfacial reaction layer. Fatigue crack will not develop from the micro-notches in the interfacial reaction layer until the thickness of the reaction layer exceeds a critical value. Matrix crack growth rate is affected by the applied stress level, however, it appears to be independent of the matrix material and heat treatment. The combined effects of fatigue crack multiplication and propagation result in stiffness degradation of the composites. The Ag/Ta duplex fiber coating significantly improves the transverse tensile and flexural creep resistance of the SCS-6/Ti-25-10 composite. However, the Ag/Ta-coated composite exhibits a shorter crack initiation life, higher number of matrix cracks, and higher crack growth rate than the uncoated composite. The embrittlement of the residual Ag/Ta layer suggests that Ag is not an effective diffusion barrier to prevent the interdiffusion of atomic species across the interface. The high interfacial cracking density and high interfacial bond strength in the Ag/Ta-coated SCS-6/Tisb3Al composite are believed to be responsible for its poor fatigue damage tolerance. For titanium alloys, the threshold intensity factor range, Delta Ksbth, for small fatigue cracks in the matrix alloys of TMCs has been determined to be between 0.9 ˜ 1.0 MPa*msp{1/2} which is much lower than that for long fatigue cracks which is ˜5 MPa*msp{1/2}. The crack growth rate fluctuates widely while the cracks are short, and converges gradually with crack growth. The transition from short fatigue crack to long fatigue crack in the SCS-6/Ti-15-3 composite has been found to occur when the crack length is in the range of 400 to 1000 mum. Finally, an interface-controlled fatigue cracking model incorporating a modified shear-lag model, the strain-life equation, and a fiber bridging model is developed to predict the fatigue crack initiation life, matrix crack growth rate, saturated matrix crack spacing, normalized matrix crack density, and residual stiffness of the composites. The predicted fatigue properties correlate well with experimental results.

  16. Surface damage and structure evolution of recrystallized tungsten exposed to ELM-like transient loads

    NASA Astrophysics Data System (ADS)

    Yuan, Y.; Du, J.; Wirtz, M.; Luo, G.-N.; Lu, G.-H.; Liu, W.

    2016-03-01

    Surface damage and structure evolution of the full tungsten ITER divertor under transient heat loads is a key concern for component lifetime and plasma operations. Recrystallization caused by transients and steady-state heat loads can lead to degradation of the material properties and is therefore one of the most serious issues for tungsten armor. In order to investigate the thermal response of the recrystallized tungsten under edge localized mode-like transient thermal loads, fully recrystallized tungsten samples with different average grain sizes are exposed to cyclic thermal shocks in the electron beam facility JUDITH 1. The results indicate that not only does the microstructure change due to recrystallization, but that the surface residual stress induced by mechanical polishing strongly influences the surface cracking behavior. The stress-free surface prepared by electro-polishing is shown to be more resistant to cracking than the mechanically polished one. The resulting surface roughness depends largely on the loading conditions instead of the recrystallized-grain size. As the base temperature increases from room temperature to 400 °C, surface roughening mainly due to the shear bands in each grain becomes more pronounced, and sub-grains (up to 3 μm) are simultaneously formed in the sub-surface. The directions of the shear bands exhibit strong grain-orientation dependence, and they are generally aligned with the traces of {1 1 2} twin habit planes. The results suggest that twinning deformation and dynamic recrystallization represent the predominant mechanism for surface roughening and related microstructure evolution.

  17. Impact of surface oxidation on damage evolution in metal matrix composites

    SciTech Connect

    Xu, S.; Lagoudas, D.C.; Allen, D.H.

    1995-12-31

    The surface oxidation in Metal Matrix Composites (MMC) with a moving oxide-metal interface is analyzed by means of a fixed grid direct finite element method (FGDFEM). Oxidation in the metal matrix is modeled by Fickian diffusion of oxygen, while the oxidation process and the resulting immobilized oxygen at the interface is accounted for by the introduction of a jump discontinuity in the oxygen concentration across the interface. The I-D problems of a uniformly growing oxide layer from the surface of a semi-infinite solid, outward oxygen diffusion and oxidation from a cylindrical cavity, as well as inward oxygen diffusion and oxidation from the surface of a cylinder, are considered as I-D benchmark problems. The 2-D plane problem of oxidation from the surface of a square is also studied as a 2-D benchmark problem. A four-ply unidirectional SiC/Ti-15-3 MMC laminate undergoing transverse tension with a pre-existing surface oxide layer is investigated using a viscoplastic finite element analysis with damage evolution modeled by failing interface elements.

  18. The discrepancies in multistep damage evolution of yttria-stabilized zirconia irradiated with different ions

    SciTech Connect

    Yang, Tengfei; Taylor, Caitlin A.; Kong, Shuyan; Wang, Chenxu; Zhang, Yanwen; Huang, Xuejun; Xue, Jianming; Yan, Sha; Wang, Yugang

    2013-01-01

    This paper reports a comprehensive investigation of structural damage in yttria-stabilized zirconia irradiated with different ions over a wide fluence range. A similar multistep damage accumulation exists for the irradiations of different ions, but the critical doses for occurrence of second damage step, characterized by a faster increase in damage fraction, and the maximum elastic strain at the first damage step are varied and depend on ion mass. For irradiations of heavier ions, the second damage step occurs at a higher dose with a lower critical elastic strain. Furthermore, larger extended defects were observed in the irradiations of heavy ions at the second damage step. Associated with other experiment results and multistep damage accumulation model, the distinct discrepancies in the damage buildup under irradiations of different ions were interpreted by the effects of electronic excitation, energy of primary knock-on atom and chemistry contributions of deposited ions.

  19. Power-law spectrum and small-world structure emerge from coupled evolution of neuronal activity and synaptic dynamics

    NASA Astrophysics Data System (ADS)

    Zeng, Hong-Li; Zhu, Chen-Ping; Guo, Yan-Dong; Teng, Ao; Jia, Jing; Kong, Hui; Zhou, Rui; Yang, Juan-Ping; Li, Su-Quan

    2015-04-01

    A co-evolutionary neuronal network model based on previous ones is proposed, and both functional and structural properties are numerically calculated. Recent experiments have revealed power-law behavior in electrocorticogram (ECoG) spectrum related with synaptic plasticity and reorganization. In the present neuronal network model, the network starts its evolution from the initial configuration of random network which is the least biased and without special structure, and the interaction rules among neurons are modified from both models by Bornholdt's and Arcangelis' groups to simulate the process of synaptic development and maturation. The system exhibits dynamic small-world structure which is the result of evolution instead of the assumption beforehand. Meanwhile, the power spectrum of electrical signals reproduces the power-law behavior with the exponent 2.0 just as what is experimentally measured in ECoG spectrum. Moreover, the power spectrum of the average degree per neuron over time also exhibits power-law behavior, with the exponent 2.0 again over more than 5 orders of magnitude. Different from previous results, our network exhibits assortative degree-degree correlation which is expected to be checked by experiments.

  20. Features in chemical kinetics. I. Signatures of self-emerging dimensional reduction from a general format of the evolution law.

    PubMed

    Nicolini, Paolo; Frezzato, Diego

    2013-06-21

    Simplification of chemical kinetics description through dimensional reduction is particularly important to achieve an accurate numerical treatment of complex reacting systems, especially when stiff kinetics are considered and a comprehensive picture of the evolving system is required. To this aim several tools have been proposed in the past decades, such as sensitivity analysis, lumping approaches, and exploitation of time scales separation. In addition, there are methods based on the existence of the so-called slow manifolds, which are hyper-surfaces of lower dimension than the one of the whole phase-space and in whose neighborhood the slow evolution occurs after an initial fast transient. On the other hand, all tools contain to some extent a degree of subjectivity which seems to be irremovable. With reference to macroscopic and spatially homogeneous reacting systems under isothermal conditions, in this work we shall adopt a phenomenological approach to let self-emerge the dimensional reduction from the mathematical structure of the evolution law. By transforming the original system of polynomial differential equations, which describes the chemical evolution, into a universal quadratic format, and making a direct inspection of the high-order time-derivatives of the new dynamic variables, we then formulate a conjecture which leads to the concept of an "attractiveness" region in the phase-space where a well-defined state-dependent rate function ? has the simple evolution ?[over dot]=-?(2) along any trajectory up to the stationary state. This constitutes, by itself, a drastic dimensional reduction from a system of N-dimensional equations (being N the number of chemical species) to a one-dimensional and universal evolution law for such a characteristic rate. Step-by-step numerical inspections on model kinetic schemes are presented. In the companion paper [P. Nicolini and D. Frezzato, J. Chem. Phys. 138, 234102 (2013)] this outcome will be naturally related to the appearance (and hence, to the definition) of the slow manifolds. PMID:23802945

  1. Features in chemical kinetics. I. Signatures of self-emerging dimensional reduction from a general format of the evolution law

    NASA Astrophysics Data System (ADS)

    Nicolini, Paolo; Frezzato, Diego

    2013-06-01

    Simplification of chemical kinetics description through dimensional reduction is particularly important to achieve an accurate numerical treatment of complex reacting systems, especially when stiff kinetics are considered and a comprehensive picture of the evolving system is required. To this aim several tools have been proposed in the past decades, such as sensitivity analysis, lumping approaches, and exploitation of time scales separation. In addition, there are methods based on the existence of the so-called slow manifolds, which are hyper-surfaces of lower dimension than the one of the whole phase-space and in whose neighborhood the slow evolution occurs after an initial fast transient. On the other hand, all tools contain to some extent a degree of subjectivity which seems to be irremovable. With reference to macroscopic and spatially homogeneous reacting systems under isothermal conditions, in this work we shall adopt a phenomenological approach to let self-emerge the dimensional reduction from the mathematical structure of the evolution law. By transforming the original system of polynomial differential equations, which describes the chemical evolution, into a universal quadratic format, and making a direct inspection of the high-order time-derivatives of the new dynamic variables, we then formulate a conjecture which leads to the concept of an "attractiveness" region in the phase-space where a well-defined state-dependent rate function ? has the simple evolution dot{? }= - ? ^2 along any trajectory up to the stationary state. This constitutes, by itself, a drastic dimensional reduction from a system of N-dimensional equations (being N the number of chemical species) to a one-dimensional and universal evolution law for such a characteristic rate. Step-by-step numerical inspections on model kinetic schemes are presented. In the companion paper [P. Nicolini and D. Frezzato, J. Chem. Phys. 138, 234102 (2013)], 10.1063/1.4809593 this outcome will be naturally related to the appearance (and hence, to the definition) of the slow manifolds.

  2. Teaching about Controversial Issues: Resolving Conflict between Creationism and Evolution through Law-Related Education.

    ERIC Educational Resources Information Center

    Morishita, Ford

    1991-01-01

    Presents a unit on evolution and creation theories in which students explore the legal issues surrounding the teaching of evolution and creation in biology. Students write preliminary essays, study conflict resolution techniques, and conduct a moot trial of the Scopes case of 1925. A course outline is provided. (MDH)

  3. A methodology for determining the evolution law of gob permeability and its distributions in longwall coal mines

    NASA Astrophysics Data System (ADS)

    Zhang, Cun; Tu, Shihao; Zhang, Lei; Bai, Qingsheng; Yuan, Yong; Wang, Fangtian

    2016-04-01

    In order to understand the permeability evolution law of the gob by mining disturbances and obtain the permeability distribution of the fully compacted gob, comprehensive methods including theoretical analyses of monitoring data and numerical simulation are used to determine the permeability of gobs in the mining process. Based on current research, three zones of the vertical stress and permeability in the gob are introduced in this article, which are the caving rock mass accumulation zone, the gradually compacted zone and the fully compacted zone. A simple algorithm is written by using FISH language to be imported into the reservoir model. FISH language is an internal programming language in FLAC3D. It is possible to calculate the permeability at each zone with this algorithm in the mining process. Besides, we analyze the gas flow rates from seven gob gas ventholes (GGV) located on a longwall face operated in a mine of a Huainan coalfield in Huainan City, China. Combined with Darcy’s law, a calculation model of permeability around GGV in the gob is proposed. Using this model, the evolution law of permeability in the gob is deduced; the phases of permeability evolution are the decline stage and the stable stage. The result of the vertical stress monitoring data and good fitting effect of the permeability to the experimental data show that the permeability decline caused by the compaction of the gob is the principal reason for the decline stage. The stable stage indicates that the gob has been fully compacted, and the average period of full gob compaction is 47.75 d. The permeability in the middle of the compacted gob is much smaller than the permeability on the edge of the gob which presents an O shape trend. Besides, the little difference among the results of the numerical simulation, the permeability calculation model and other commonly used calculation models validate the correctness of the permeability calculation model and numerical simulation results.

  4. Low velocity impact response and damage evolution in unreinforced resin systems and self-repairing polymer matrix composites

    NASA Astrophysics Data System (ADS)

    Motuku, Molefi

    The low velocity impact response and damage evolution in unreinforced polymer matrices, conventional polymer matrix composites, and self-repairing polymer matrix composites was investigated. The impact response study of unreinforced matrices and conventional laminates was undertaken because the failure initiation energies, threshold energy levels, failure characteristics and damage evolution in both the matrix material (unreinforced resin plaques) and the composite are intrinsic to proper design of a self-repairing composite. The self-repairing concept was investigated due to its attractive potential to alleviate damage problems in polymer matrix composites. Self-repairing composites, which fall under the category of passive smart polymer composites, have the potential to self repair both micro- and macro-damage resulting from impacts as well as non-impact loading. The self-repairing mechanism is achieved through the incorporation of hollow fibers in addition to the normal solid reinforcing fibers. The hollow fibers store the damage-repairing solution or chemicals that are released into the matrix or damaged zone upon fiber failure to repair and/or arrest damage progression. The room temperature low velocity impact response and damage evolution in DERAKANE 411-350 and 411-C50 vinyl ester unreinforced resin systems was investigated as a function of impact energy level, sample thickness, matrix material and catalyst system. The low velocity impact response of conventional and self-repairing glass reinforced polymer composites was investigated by addressing the fabrication and some of the parameters that influence their response to low velocity impact loading. Specific issues addressed by this study include developing a process to fabricate self-repairing laminates, processing quality; selection of storage material for the repairing solution; release and transportation of repairing solution; the effect of the number, type and spatial distribution of the repairing tubes, specimen thickness, matrix material and impact energy level. Plain weave S-2 glass fabric reinforcement, vinyl ester 411-C50, and EPON-862 epoxy resin systems were considered in the study of conventional and self-repairing laminates. Composite panels were fabricated by using vacuum assisted resin transfer molding (VARTM) process. The response of unreinforced resin plaques, conventional laminates and self-repairing laminates to low-velocity impact loading was investigated using the impact load histories, impact plots and fractography analysis.

  5. Padova Charter on personal injury and damage under civil-tort law : Medico-legal guidelines on methods of ascertainment and criteria of evaluation.

    PubMed

    Ferrara, Santo Davide; Baccino, Eric; Boscolo-Berto, Rafael; Comandè, Giovanni; Domenici, Ranieri; Hernandez-Cueto, Claudio; Gulmen, Mete Korkut; Mendelson, George; Montisci, Massimo; Norelli, Gian Aristide; Pinchi, Vilma; Ranavaya, Mohammed; Shokry, Dina A; Sterzik, Vera; Vermylen, Yvo; Vieira, Duarte Nuno; Viel, Guido; Zoja, Riccardo

    2016-01-01

    Compensation for personal damage, defined as any pecuniary or non-pecuniary loss causally related to a personal injury under civil-tort law, is strictly based on the local jurisdiction and therefore varies significantly across the world. This manuscript presents the first "International Guidelines on Medico-Legal Methods of Ascertainment and Criteria of Evaluation of Personal Injury and Damage under Civil-Tort Law". This consensus document, which includes a step-by-step illustrated explanation of flow charts articulated in eight sequential steps and a comprehensive description of the ascertainment methodology and the criteria of evaluation, has been developed by an International Working Group composed of juridical and medico-legal experts and adopted as Guidelines by the International Academy of Legal Medicine (IALM). PMID:26342285

  6. Spatiotemporal evolution of blood brain barrier damage and tissue infarction within the first 3h after ischemia onset.

    PubMed

    Jin, Xinchun; Liu, Jie; Yang, Yi; Liu, Ke J; Yang, Yirong; Liu, Wenlan

    2012-12-01

    Blood brain barrier (BBB) damage that occurs within the thrombolytic time window is increasingly appreciated to negatively impact the safety and efficacy profiles of thrombolytic therapy for ischemic stroke. However, the spatiotemporal evolution of BBB damage in this early stroke stage and the underlying mechanisms remain unclear. Here, we investigated the topographical distribution of BBB damage and its association with tissue injury within the first 3 h after ischemia onset and the roles of matrix metalloproteinase (MMP)-2/9 in this process. Rats were subjected to 1, 2, or 3 h of middle cerebral artery occlusion (MCAO) followed by 10 min reperfusion with fluorescence-labeled dextran as BBB permeability marker. Acute tissue infarction was evidenced by staining defect with triphenyltetrazolium chloride (TTC). Cerebral blood flow (CBF) was measured by magnetic resonance imaging. MMP-2/9 were assessed by gel and in situ zymography. After 2-h MCAO, dextran leakage was seen in the ischemic ventromedial striatum and the preoptic area which showed ~70% CBF reduction, and expanded to other MCA regions including the cortex after 3-h MCAO. Interestingly, high (2000 kDa) and low (70 kDa) molecular weight dextrans displayed almost identical leakage patterns. Different from BBB damage, tissue infarction was first seen in the ischemic dorsal striatum and the parietal/insular cortex which experienced ~90% CBF reduction. Increased gelatinolytic activity colocalized with dextran leakage, and MMP-2 was found to be the major enzymatic source on gelatin zymograms. Pretreatment with MMP inhibitor GM6001 significantly reduced dextran leakage induced by 2-h and 3-h MCAO. Taken together, our findings reveal substantial differences in the topographic distribution of BBB damage and tissue infarction within the first 3 h after MCAO onset. Unlike ischemic neuronal damage, BBB damage appears to develop faster in brain regions with moderately severe ischemia, and MMP-2 contributes to this early ischemic BBB damage. PMID:22813865

  7. Study of the damage evolution function of tin silver copper in cycling

    NASA Astrophysics Data System (ADS)

    Qasaimeh, Awni

    The present research focused on the assessment of solder joint fatigue life in microelectronics assemblies. A general concern of any reliability engineer is whether accelerated tests are relevant to field conditions. The risk of this was minimized by developing an approach to reduce the duration of an accelerated thermal cycling test, thus allowing for the use of less accelerated test conditions. For this purpose the conventional dye and pry technique was improved and used together with artificial neural networks to measure and characterize very early stages of crack growth. The same work also demonstrated a quantitative link between thermal cycling induced recrystallization and a strong acceleration of the subsequent fatigue crack growth and failure. A new study was conducted in which different combinations of annealing and isothermal cycling provided a systematic characterization of the effects of a range of individual parameters on the recrystallization. Experiments showed the ongoing coarsening of secondary precipitates to have a clear effect on recrystallization. The rate of recrystallization was also shown not to scale with the inelastic energy deposition. This means that the most popular current thermal cycling model cannot apply to SnAgCu solder joints. Recrystallization of the Sn grains is usually not the rate limiting mechanism in isothermal cycling. The crack initiation stage often takes up a much greater fraction of the overall life, and the eventual failure of BGA joints tends to involve transgranular crack growth instead. Cycling of individual solder joints allowed for monitoring of the evolution of the solder properties and the rate of inelastic energy deposition. Both the number of cycles to crack initiation and the subsequent number of cycles to failure were shown to be determined by the inelastic energy deposition. This provides for a simple model for the extrapolation of accelerated test results to the much milder cycling amplitudes characteristic of long term service conditions based on conventional Finite Element Modeling. It also offers a critical basis for the ongoing development of a practical model to account for the often dramatic break-down of Miner's rule of linear damage accumulation under variable cycling amplitudes as expected in realistic applications.

  8. Menzerath-Altmann law in mammalian exons reflects the dynamics of gene structure evolution.

    PubMed

    Nikolaou, Christoforos

    2014-12-01

    Genomic sequences exhibit self-organization properties at various hierarchical levels. One such is the gene structure of higher eukaryotes with its complex exon/intron arrangement. Exon sizes and exon numbers in genes have been shown to conform to a law derived from statistical linguistics and formulated by Menzerath and Altmann, according to which the mean size of the constituents of an entity is inversely related to the number of these constituents. We herein perform a detailed analysis of this property in the complete exon set of the mouse genome in correlation to the sequence conservation of each exon and the transcriptional complexity of each gene locus. We show that extensive linear fits, representative of accordance to Menzerath-Altmann law are restricted to a particular subset of genes that are formed by exons under low or intermediate sequence constraints and have a small number of alternative transcripts. Based on this observation we propose a hypothesis for the law of Menzerath-Altmann in mammalian genes being predominantly due to genes that are more versatile in function and thus, more prone to undergo changes in their structure. To this end we demonstrate one test case where gene categories of different functionality also show differences in the extent of conformity to Menzerath-Altmann law. PMID:25155263

  9. Limitations on the Evolution of Quantum Coherences: Towards Fully Quantum Second Laws of Thermodynamics

    NASA Astrophysics Data System (ADS)

    Ćwikliński, Piotr; Studziński, Michał; Horodecki, Michał; Oppenheim, Jonathan

    2015-11-01

    The second law of thermodynamics places a limitation into which states a system can evolve into. For systems in contact with a heat bath, it can be combined with the law of energy conservation, and it says that a system can only evolve into another if the free energy goes down. Recently, it's been shown that there are actually many second laws, and that it is only for large macroscopic systems that they all become equivalent to the ordinary one. These additional second laws also hold for quantum systems, and are, in fact, often more relevant in this regime. They place a restriction on how the probabilities of energy levels can evolve. Here, we consider additional restrictions on how the coherences between energy levels can evolve. Coherences can only go down, and we provide a set of restrictions which limit the extent to which they can be maintained. We find that coherences over energy levels must decay at rates that are suitably adapted to the transition rates between energy levels. We show that the limitations are matched in the case of a single qubit, in which case we obtain the full characterization of state-to-state transformations. For higher dimensions, we conjecture that more severe constraints exist. We also introduce a new class of thermodynamical operations which allow for greater manipulation of coherences and study its power with respect to a class of operations known as thermal operations.

  10. Limitations on the Evolution of Quantum Coherences: Towards Fully Quantum Second Laws of Thermodynamics.

    PubMed

    Ćwikliński, Piotr; Studziński, Michał; Horodecki, Michał; Oppenheim, Jonathan

    2015-11-20

    The second law of thermodynamics places a limitation into which states a system can evolve into. For systems in contact with a heat bath, it can be combined with the law of energy conservation, and it says that a system can only evolve into another if the free energy goes down. Recently, it's been shown that there are actually many second laws, and that it is only for large macroscopic systems that they all become equivalent to the ordinary one. These additional second laws also hold for quantum systems, and are, in fact, often more relevant in this regime. They place a restriction on how the probabilities of energy levels can evolve. Here, we consider additional restrictions on how the coherences between energy levels can evolve. Coherences can only go down, and we provide a set of restrictions which limit the extent to which they can be maintained. We find that coherences over energy levels must decay at rates that are suitably adapted to the transition rates between energy levels. We show that the limitations are matched in the case of a single qubit, in which case we obtain the full characterization of state-to-state transformations. For higher dimensions, we conjecture that more severe constraints exist. We also introduce a new class of thermodynamical operations which allow for greater manipulation of coherences and study its power with respect to a class of operations known as thermal operations. PMID:26636834

  11. Numerical simulation of the damage evolution in the pelvic floor muscles during childbirth.

    PubMed

    Oliveira, Dulce A; Parente, Marco P L; Calvo, Begoña; Mascarenhas, Teresa; Natal Jorge, Renato M

    2016-02-29

    Several studies have shown that pelvic floor injuries during a vaginal delivery can be considered a significant factor in the development of pelvic floor dysfunction. Such disorders include a group of conditions affecting women like urinary incontinence, pelvic organ prolapse and fecal incontinence. Numerical simulations are valuable tools that are contributing to the clarification of the mechanisms behind pelvic floor disorders. The aim of this work is to propose a mechanical model implemented in the finite element method context to estimate the damage in the pelvic floor muscles by mechanical effects during a vaginal delivery of a fetus in vertex presentation and occipitoanterior position. The constitutive model adopted has already been successfully used in the simulation of childbirth and the structural damage model added has previously been applied to characterize the damage process in biological soft tissues undergoing finite deformations. The constitutive parameters were fit to experimental data available in the literature and the final proposed material model is suitable to estimate the mechanical damage in the pelvic floor muscle during a vaginal delivery. The computational model predicts that even an apparently uneventful vaginal delivery inflicts injuries to the pelvic floor muscles, particularly during the extension of the fetus head, having been obtained more than 10% of damaged fibers. As a clinical evidence, the present work allows to conclude that the puborectalis component of the levator ani muscle is the most prone to damage. PMID:26895779

  12. DNA repair and the evolution of transformation in Bacillus subtilis. 3. Sex with damaged DNA

    SciTech Connect

    Hoelzer, M.A.; Michod, R.E. )

    1991-06-01

    Natural genetic transformation in the bacterium Bacillus subtilis provides an experimental system for studying the evolutionary function of sexual recombination. The repair hypothesis proposes that during transformation the exogenous DNA taken up by cells is used as template for recombinational repair of damages in the recipient cell's genome. Earlier results demonstrated that the population density of transformed cells (i.e., sexual cells) increases, relative to nontransformed cells (primarily asexual cells), with increasing dosage of ultraviolet irradiation, provided that the cells are transformed with undamaged homologous DNA after they have become damaged. In nature, however, donor DNA for transformation is likely to come from cells that are as damaged as the recipient cells. In order to better simulate the effects of transformation in natural populations we conducted similar experiments as those just described using damaged donor DNA. The authors document in this report that transformants continue to increase in relative density even if they are transformed with damaged donor DNA. These results suggest that sites of transformation are often damaged sites in the recipient cell's genome.

  13. A coarse-grained model of thermally activated damage in heterogeneous media: Time evolution of the creep rate

    NASA Astrophysics Data System (ADS)

    Baxevanis, Th.

    2008-08-01

    A coarse-grained mean-field model is proposed where the damage enhanced creep of heterogeneous materials is described by the theory of absolute reaction rates. The dynamics of the proposed model, below a critical load, is characterized by an intensive precursor activity in the form of avalanches of microscopic breaking events that leads to a final catastrophic cascade occurring at a finite strain. Above the critical load, failure is instantaneous. The critical load is the static (elastic) fracture strength; thus the model is consistent with its time-independent analogue. Finally, the proposed model reproduces the experimental observations on the time evolution of the creep rate.

  14. Comparing monofractal and multifractal analysis of corrosion damage evolution in reinforcing bars.

    PubMed

    Xu, Yidong; Qian, Chunxiang; Pan, Lei; Wang, Bingbing; Lou, Chi

    2012-01-01

    Based on fractal theory and damage mechanics, the aim of this paper is to describe the monofractal and multifractal characteristics of corrosion morphology and develop a new approach to characterize the nonuniform corrosion degree of reinforcing bars. The relationship between fractal parameters and tensile strength of reinforcing bars are discussed. The results showed that corrosion mass loss ratio of a bar cannot accurately reflect the damage degree of the bar. The corrosion morphology of reinforcing bars exhibits both monofractal and multifractal features. The fractal dimension and the tensile strength of corroded steel bars exhibit a power function relationship, while the width of multifractal spectrum and tensile strength of corroded steel bars exhibit a linear relationship. By comparison, using width of multifractal spectrum as multifractal damage variable not only reflects the distribution of corrosion damage in reinforcing bars, but also reveals the influence of nonuniform corrosion on the mechanical properties of reinforcing bars. The present research provides a new approach for the establishment of corrosion damage constitutive models of reinforcing bars. PMID:22238682

  15. Comparing Monofractal and Multifractal Analysis of Corrosion Damage Evolution in Reinforcing Bars

    PubMed Central

    Xu, Yidong; Qian, Chunxiang; Pan, Lei; Wang, Bingbing; Lou, Chi

    2012-01-01

    Based on fractal theory and damage mechanics, the aim of this paper is to describe the monofractal and multifractal characteristics of corrosion morphology and develop a new approach to characterize the nonuniform corrosion degree of reinforcing bars. The relationship between fractal parameters and tensile strength of reinforcing bars are discussed. The results showed that corrosion mass loss ratio of a bar cannot accurately reflect the damage degree of the bar. The corrosion morphology of reinforcing bars exhibits both monofractal and multifractal features. The fractal dimension and the tensile strength of corroded steel bars exhibit a power function relationship, while the width of multifractal spectrum and tensile strength of corroded steel bars exhibit a linear relationship. By comparison, using width of multifractal spectrum as multifractal damage variable not only reflects the distribution of corrosion damage in reinforcing bars, but also reveals the influence of nonuniform corrosion on the mechanical properties of reinforcing bars. The present research provides a new approach for the establishment of corrosion damage constitutive models of reinforcing bars. PMID:22238682

  16. Space Law

    NASA Astrophysics Data System (ADS)

    Hermida, Julian

    2006-01-01

    This chapter examines the salient characteristics of Space Law. It analyzes the origins and evolution of Space Law, its main international principles, and some current topics of interest to the scientific community: the delimitation of airspace and outer space, intellectual property, and criminal responsibility.

  17. From Migmatites to Plutons: Power Law Relationships in the Evolution of Magmatic Bodies

    NASA Astrophysics Data System (ADS)

    Soesoo, Alvar; Bons, Paul D.

    2015-07-01

    Magma is generated by partial melting from micrometre-scale droplets at the source and may accumulate to form >100 km-scale plutons. Magma accumulation thus spans well over ten orders of magnitude in scale. Here we provide measurements of migmatitic leucosomes and granitic veins in drill cores from the Estonian Proterozoic basement and outcrops at Masku in SW Finland and Montemor-o-Novo, central Portugal. Despite the differences in size and number of measured leucosomes and magmatic veins, differences in host rock types and metamorphic grades, the cumulative width distribution of the studied magmatic leucosomes/veins follows a power law with exponents usually between 0.7 and 1.8. Published maps of the SE Australian Lachlan Fold Belt were used to investigate the distribution of granitoid pluton sizes. The granites occupy ca. 22 % of the 2.6 × 105 km2 area. The cumulative pluton area distributions show good power law distributions with exponents between 0.6 and 0.8 depending on pluton area group. Using the self-affine nature of pluton shapes, it is possible to estimate the total volume of magma that was expelled from the source in the 2.6 × 105 km2 map area, giving an estimated 0.8 km3 of magma per km2. It has been suggested in the literature that magma batches in the source merge to form ever-bigger batches in a self-organized way. This leads to a power law for the cumulative distribution of magma volumes, with an exponent m V between 1 for inefficient melt extraction, and 2/3 for maximum accumulation efficiency as most of the volume resides in the largest batches that can escape from the source. If m V ≥ 1, the mass of the magma is dominated by small batches; in case m = 2/3, about 50 % of all magma in the system is placed in a single largest batch. Our observations support the model that the crust develops a self-organized critical state during magma generation. In this state, magma batches accumulate in a non-continuous, step-wise manner to form ever-larger accumulations. There is no characteristic length or time scale in the partial melting process or its products. Smallest melt segregations and >km-scale plotuns form the end members of a continuous chain of mergers of magma batches.

  18. Implication of the power law cutoff evolution in XTE J1550-564

    NASA Astrophysics Data System (ADS)

    Titarchuk, Lev; Shaposhnikov, Nikolai

    We present spectral analysis of data collected using RXTE during two periods of X-ray activity in 1998 and 2000 from the Galactic X-ray black hole binary XTE J1550-564. We particularly concentrate on the behavior of the high energy cutoff of the power law part of the spectrum. The 1998 event was very powerful, showing a quick initial transition from low-hard state to very high state. The power law cutoff energy decreases from low-hard to intermediate states and increased again during transition to very high and high-soft states. For the 2000 outburst we also observe the decrease of the cutoff energy during the start of the state transition, similar to that in 1998 outburst, however the increase of the high energy cutoff (folding energy) is not apparent in this track because the source does not reach the real high-soft state in this event. We attribute this difference in the cutoff energy behavior to the different partial contributions of the thermal and non-thermal (bulk motion) Comptonization in photon upscattering. Namely, during the 1998 event higher accretion rate presumably provided more cooling to Comptonizing media and thus reducing the effectiveness of the thermal upscattering process. Under these conditions the bulk motion should take a leading role in boosting the input soft photons. This observational behavior of the cutoff energy presents an additional evidence of the existence of the converging bulk motion region near the central objects and provides further support for the previously reported index saturations effect as a black hole signature.

  19. Permeability of natural rock salt from the Waste Isolation Pilot Plant (WIPP) during damage evolution and healing

    SciTech Connect

    Pfeifle, T.W.

    1998-06-01

    The US Department of Energy has developed the Waste Isolation Pilot Plant (WIPP) in the bedded salt of southeastern New Mexico to demonstrate the safe disposal of radioactive transuranic wastes. Four vertical shafts provide access to the underground workings located at a depth of about 660 meters. These shafts connect the underground facility to the surface and potentially provide communication between lithologic units, so they will be sealed to limit both the release of hazardous waste from and fluid flow into the repository. The seal design must consider the potential for fluid flow through a disturbed rock zone (DRZ) that develops in the salt near the shafts. The DRZ, which forms initially during excavation and then evolves with time, is expected to have higher permeability than the native salt. The closure of the shaft openings (i.e., through salt creep) will compress the seals, thereby inducing a compressive back-stress on the DRZ. This back-stress is expected to arrest the evolution of the DRZ, and with time will promote healing of damage. This paper presents laboratory data from tertiary creep and hydrostatic compression tests designed to characterize damage evolution and healing in WIPP salt. Healing is quantified in terms of permanent reduction in permeability, and the data are used to estimate healing times based on considerations of first-order kinetics.

  20. Constitutive behavior, texture and damage evolution in BCC metal using taylor impact test.

    SciTech Connect

    Trujillo, C. P.; Gray, G. T. , III; Chen, S. R.; Chavez, R. L.

    2004-01-01

    To capture the evolution of anisotropy in textured metals under high rate conditions, we developed a method that enables us to digitally resolve this event. Using a Taylor Anvil Test Facility, we dynamically deformed unalloyed Ta, while capturing real time digital images of the radial flow at the impact surface. We measured the elliptical footprint and plotted its eccentricity (ratio of major to minor diameters) versus real time. The current engineering strength constitutive models allow for an initial texture, but they cannot accurately predict the texture evolution during deformation. This test will allow us to track anisotropy to better validate our constitutive models.

  1. Toward a mechanistic understanding of the damage evolution of SnAgCu solder joints in accelerated thermal cycling test

    NASA Astrophysics Data System (ADS)

    Mahin Shirazi, Sam

    Accelerated thermal cycling (ATC) tests are the most commonly used tests for the thermo-mechanical performance assessment of microelectronics assemblies. Currently used reliability models have failed to incorporate the microstructural dependency of lead free solder joint behavior and its microstructure evolution during cycling. Thus, it is essential to have a mechanistic understanding of the effect of cycling parameters on damage evolution and failure of lead free solder joints in ATC. Recrystallization has been identified as the damage rate controlling mechanism in ATC. Usually it takes 1/3 of life for completion of recrystallization regardless of cycling parameters. Thus, the life of the solder joints can be predicted by estimating global recrystallization. The objective of the first part of the study was to examine whether the damage scenario applies in service is the same as the harsh thermal cycling tests (i.e. 0/100 °C and -40/125 °C) commonly used in industry. Microstructure analysis results on a variety of lead free solder SnAgCu assemblies subjected to the both harsh (0/100 °C) and mild (20/80 °C) ATC confirmed similar failure mechanism under the both testing conditions. Sn grain morphology (interlaced versus beach ball) has a significant effect on the thermo-mechanical performance (and thus the model) of the lead free solder joints. The longer thermal cycling lifetime observed in the interlaced solder joints subjected to the ATC compared to the beach ball structure was correlated to the different initial microstructure and the microstructure evolution during cycling. For the modeling proposes, the present study was focused on Sn-Ag-Cu solder joints with either a single Sn grain or beach ball structure. Microstructural analysis results of the simulated thermal cycling experiment revealed that, the life can be approximated as determined by the accumulation of a certain amount of work during the high temperature dwells. Finally the effect of precipitates spacing on acceleration factor was investigated. Results indicated that a smaller initial precipitate spacing would tend to result in a longer life in mild thermal cycling/service (where there is lower stresses). Accordingly, it is essential to incorporate the dependence of damage rate (i.e. recrystallization) on precipitate coarsening in any predictions.

  2. Characterizing Damage Evolution and Yield in Sandstone Under Triaxial Loading as a Function of Changing Effective Pressure

    NASA Astrophysics Data System (ADS)

    Choens, R. C.; Chester, F. M.

    2009-12-01

    Experimental rock deformation was used to study 1) the accumulation of microscopic damage preceding macroscopic failure across the brittle-ductile transition (BDT) in granular porous rocks, 2) how damage induced at one effective pressure (P) affects failure at a different P, and 3) the appropriateness of single yield envelope versus multiple yield envelope models. Granular porous material is idealized as an elastic-plastic material, where failure occurs by localized dilatant shear at low P and compactant cataclastic flow at high P. Given distinct failure modes in the low and high P regimes, different types of damage may develop prior to failure at different P. As such, yielding of porous rocks has been modeled with a single yield envelope, or with two distinct yield envelopes corresponding to the different failure modes. Water saturated cylinders of Berea sandstone (18% porosity, 185 m grain size) were deformed in triaxial compression at a shortening rate of 4 m/s. During each experiment, the confining and pore pressure were held constant; acoustic emissions (AE), axial stress, axial displacement, and pore volume changes were recorded. Samples were deformed at pore pressures of 10, 20, and 30 MPa, and confining pressures of 50, 180, and 260 MPa to investigate the brittle, transitional, and ductile regimes. Three different load paths were used. The first involved loading to failure to establish a baseline response. The second involved initial loading to 80% of the differential stress at failure, unloading, and reloading to failure at a different pore pressure. The third was similar to the second, except confining pressure was changed between load and reload to cause failure in a different regime than the initial load. AE is used to quantify damage evolution, and the Kaiser effect was used to map damage states in stress space. The experiments show that contours of equivalent damage are subparallel to the failure envelope across the BDT, and that macroscopic failure depends on load path and the cumulative damage state. Damage induced in either the low or high pressure regimes has little effect for failure in the other deformation regime, supporting the concept of distinct processes and damage development in the two regimes. The behavior across the brittle-ductile transition is most consistent with a model based on two distinct yield envelopes each associated with distinct damage mechanisms and a sharp transition between the low and high pressure regimes. These results could be important in predicting formation damage and permeability changes in over-pressured reservoirs that undergo large drops in pore pressure, as well as for reservoirs undergoing advance recovery methods and sequestration that increase pore pressure. This could also aid in understanding deformation in tectonic basins that experienced P changes due to burial or exhumation, or from cyclic loading along faults.

  3. Deformation Failure Characteristics of Coal Body and Mining Induced Stress Evolution Law

    PubMed Central

    Wen, Zhijie; Wen, Jinhao; Shi, Yongkui; Jia, Chuanyang

    2014-01-01

    The results of the interaction between coal failure and mining pressure field evolution during mining are presented. Not only the mechanical model of stope and its relative structure division, but also the failure and behavior characteristic of coal body under different mining stages are built and demonstrated. Namely, the breaking arch and stress arch which influence the mining area are quantified calculated. A systematic method of stress field distribution is worked out. All this indicates that the pore distribution of coal body with different compressed volume has fractal character; it appears to be the linear relationship between propagation range of internal stress field and compressed volume of coal body and nonlinear relationship between the range of outburst coal mass and the number of pores which is influenced by mining pressure. The results provide theory reference for the research on the range of mining-induced stress and broken coal wall. PMID:24967438

  4. Contact behavior evolution induced by damage growth in radio-frequency microelectromechanical system switches

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Peroulis, D.

    2015-02-01

    This study provides a two-contact-event model to explain the evolution of the contact behavior of microelectromechanical system (MEMS) switches through their lifetime. The succession of two dynamic contact events is carefully considered during actuation inspired by experimental observations. The contact between the MEMS switch tip and the drain can be treated as an effective contact between an elastic hemisphere and a rigid plane. If the first contact event results in elastic deformation, the effective hemisphere will fully recover. Consequently, the subsequent contact event also produces elastic deformation. If, on the other hand, the first contact event induces elastoplastic or plastic deformation, a residual depth will be produced between the hemisphere and the rigid plane. The contact force of the subsequent contact event can be significantly reduced due to this additional residual depth. With the growth of residual depth during the switch cycling process, the modeling results show three possible situations of contact radius evolution: (1) The contact radius increases to a maximum value and then decreases to zero; (2) the contact radius increases to one local maximum value; then decreases to a local minimum value; subsequently increases again to another maximum value, and finally decreases to zero; and (3) the contact radius increases to one maximum value and then decreases to zero; after an intermittent response, the contact radius increases again to another maximum value and finally decreases to zero. Furthermore, the Maxwell spreading formula is applied to determine the contact resistance which is inversely proportional to the contact radius. Three situations of contact resistance evolution corresponding to the evolution of contact radius are obtained. All three situations are also observed and validated by the experimental results.

  5. Patterns of evolution of myocyte damage after human heart transplantation detected by indium-111 monoclonal antimyosin

    SciTech Connect

    Ballester-Rodes, M.; Carrio-Gasset, I.; Abadal-Berini, L.; Obrador-Mayol, D.; Berna-Roqueta, L.; Caralps-Riera, J.M.

    1988-09-15

    The indium-111 labeled Fab fragment of antimyosin monoclonal antibody was used to study cardiac rejection and the time course of myocyte damage after transplantation. Fifty-three studies were performed in 21 patients, 17 men and 4 women, aged 19 to 54 years (mean 37 +/- 8), from 7 to 40 months after transplantation. Repeat studies were available in 8, and 10 were studied after the first year of transplantation. A heart-to-lung ratio was used for quantitation of uptake (normal 1.46 +/- 0.04). Differences between absent (1.69 +/- 0.29) and moderate (1.90 +/- 0.36) rejection were significant (p less than 0.03). Antimyosin ratio at 1 to 3 months (1.89 +/- 0.35) differed from that at greater than 12 months (1.65 +/- 0.2) (p less than 0.01). Repeat studies revealed a decrease in antimyosin ratio in 5 patients with uneventful clinical course; 2 had persistent activity after transplantation and suffered heart failure from rejection. After 1 year of transplantation uptake was within normal limits in 7 of 10 patients, and high uptake was associated with vascular rejection in 1. Because they can define evolving patterns of myocardial lesion activity, antimyosin studies could be useful both in patient management and in concentrating resources for those patients who most require them. The heart-to-lung ratio is suggested to monitor sequentially the degree of myocyte damage after transplantation.

  6. Damage evolution in acetabular replacements under long-term physiological loading conditions.

    PubMed

    Wang, J-Y; Heaton-Adegbile, P; New, A; Hussell, J G; Tong, J

    2009-05-29

    Damage development in cemented acetabular replacements has been studied in bovine pelvic bones under long-term physiological loading conditions, including normal walking, stair climbing and a combined block loading with representative routine activities. The physiological loading conditions were achieved using a specially designed hip simulator for fixation endurance testing. Damage was detected and monitored using micro-CT scanning at regular intervals of the experiments, and verified by microscopic studies post testing. The results show that debonding at the bone-cement interface defined the failure of cement fixation in all cases, and debondings initiated near the dome of the acetabulum in the superior-posterior quadrant, consistent with the high-stress region identified from the finite element analysis of implanted acetabular models Zant, N.P., Heaton-Adegbile, P., Hussell, J.G., Tong, J., 2008b. In-vitro fatigue failure of cemented acetabular replacements-a hip simulator study. Journal of Biomechanical Engineering, Transactions of the ASME, 130, 021019-1-9]; [Tong, J., Zant, N.P., Wang, J-Y., Heaton-Adegbile, P., Hussell, J.G., 2008. Fatigue in cemented acetabulum. International Journal of Fatigue, 30(8), 1366-1375]. PMID:19345357

  7. Dictyostelium discoideum, a lower eukaryote model for the study of DNA repair: Implications for the role of DNA-damaging chemicals in the evolution of repair proficient cells

    NASA Astrophysics Data System (ADS)

    Deering, R. A.

    1994-10-01

    The evolution of the ability of living cells to cope with stress is crucial for the maintenance of their genetic integrity. Yet low levels of mutation must remain to allow adaptation to environmental changes. The cellular slime mold D. discoideum is a good system for studying molecular aspects of the repair of lethal and mutagenic damage to DNA by radiation and chemicals. The wild-type strains of this soil microorganism are extremely resistant to DNA damaging agents. In nature the amoeboid cells in their replicative stage feed on soil bacteria and are exposed to numerous DNA-damaging chemicals produced by various soil microorganisms. It is probable that the evolution of repair systems in this organism and perhaps in others is a consequence of the necessity to cope with chemical damage which also confers resistance to radiation.

  8. The effects of shockwave profile shape and shock obliquity on spallation in Cu and Ta: kinetic and stress-state effects on damage evolution(u)

    SciTech Connect

    Gray, George T

    2010-12-14

    Widespread research over the past five decades has provided a wealth of experimental data and insight concerning shock hardening and the spallation response of materials subjected to square-topped shock-wave loading profiles. Less quantitative data have been gathered on the effect of direct, in-contact, high explosive (HE)-driven Taylor wave (or triangular-wave) loading profile shock loading on the shock hardening, damage evolution, or spallation response of materials. Explosive loading induces an impulse dubbed a 'Taylor Wave'. This is a significantly different loading history than that achieved by a square-topped impulse in terms of both the pulse duration at a fixed peak pressure, and a different unloading strain rate from the peak Hugoniot state achieved. The goal of this research is to quantify the influence of shockwave obliquity on the spallation response of copper and tantalum by subjecting plates of each material to HE-driven sweeping detonation-wave loading and quantify both the wave propagation and the post-mortem damage evolution. This talk will summarize our current understanding of damage evolution during sweeping detonation-wave spallation loading in Cu and Ta and show comparisons to modeling simulations. The spallation responses of Cu and Ta are both shown to be critically dependent on the shockwave profile and the stress-state of the shock. Based on variations in the specifics of the shock drive (pulse shape, peak stress, shock obliquity) and sample geometry in Cu and Ta, 'spall strength' varies by over a factor of two and the details of the mechanisms of the damage evolution is seen to vary. Simplistic models of spallation, such as P{sub min} based on 1-D square-top shock data lack the physics to capture the influence of kinetics on damage evolution such as that operative during sweeping detonation loading. Such considerations are important for the development of predictive models of damage evolution and spallation in metals and alloys.

  9. Creep in Thermally Cracked Granite: Physical, Mechanical and Damage Properties Evolution

    NASA Astrophysics Data System (ADS)

    Wang, X.; Schubnel, A. J.; Fortin, J.; Gueguen, Y.; Ge, H.

    2011-12-01

    We investigate the effects of pervasive crack damage on the rupture processes of a fine-grained granite, under triaxial stress, in wet (H20) and dry (argon gas) saturated conditions, at room temperature. Eight samples of La Peyratte granite (a granodiorite with an average grain size of 200 microns) were cored with an initial porosity of <1%. Damage was introduced by heating four samples up to 700°C. These were then compared to the intact granite specimens. 4 samples were deformed at a constant strain rate of 2x10-6/s until brittle failure occurred. 4 other samples were deformed in creep conditions. During these 8 experiments, at each step, we recorded strains, elastic wave velocities and Acoustic Emissions (AE). Our main results are: 1. The brittle strength of the sample remained unchanged (approx. 500MPa deviatoric stress at 30MPa effective pressure), whether the sample was heat-treated or not. We did not observe any significant water weakening as well. However, the onset of dilatancy was observed at lower deviatoric stress in the heat-treated specimen than for the intact ones. 2. Acoustic emissions revealed useful in order to image the rupture processes. Indeed, AE locations and Focal mechanism were in good agreement with the post mortem analysis of sample. In intact specimen, failure occurred after a larger premonitory AE activity, while heat-treated specimen had a longer aftershocks activity. In creep conditions, we show that extreme damage localization is already initiated during the primary and secondary creep phases. 3. However, in all our experiments, we observed the development of an elastic fabric well before the onset of rupture. To be more precise, measuring the P wave velocities along two different horizontal travel paths - one perpendicular and one parallel to the eventual rupture plane, away from the nucleation zone - we showed that that both started to diverge as early as at 70% of the final rupture strength. This shows that quite early on during the experiment, the strain localization processes have started and the final fault orientation has already been selected.

  10. Slip, Crystal Orientation, and Damage Evolution During Thermal Cycling in High-Strain Wafer-Level Chip-Scale Packages

    NASA Astrophysics Data System (ADS)

    Zhou, Bite; Zhou, Quan; Bieler, Thomas R.; Lee, Tae-kyu

    2015-03-01

    Wafer-level chip-scale package samples with pre-cross-sectioned edge rows were thermally cycled to study microstructure evolution and damage development. Electron backscattered diffraction (EBSD) and high-energy x-ray diffraction were used to obtain Sn grain orientations and the average coefficient of thermal expansion normal to the board in every joint of the package for samples in the as-fabricated and thermally cycled conditions. The results indicated a near-random distribution of joint orientation. Optical, scanning electron microscopy, and EBSD methods were used to characterize microstructure changes in pre-cross-sectioned samples due to thermal cycling. Slip trace analysis and Orientation Imaging Microscopy™ (OIM) show that slip systems with high Schmid factors (estimated global shear stress based on the package neutral point) are responsible for the observed microstructure evolution during thermal cycling, which provides information about slip systems that are more easily activated. Two joints were analyzed in detail to evaluate slip activity at different stages of their thermal history. The first case showed that a solidification twin grain boundary misorientation deviated from the twin relationship due to slip activity during thermal cycling, which can influence damage development and the path of crack propagation. The second case showed a new grain orientation developing due to gradual lattice rotation about the Sn [110] axis by a continuous recrystallization mechanism. This rotation was correlated with the operation of slip system . Small tin whiskers emerged from the initially polished chip interface and grew with increasing thermal cycles until a crack developed in the solder that relieved the stress. As the local stresses are not known experimentally, this analysis provides observations that can be compared with a crystal plasticity model simulation.

  11. Models for predicting damage evolution in metal matrix composites subjected to cyclic loading

    SciTech Connect

    Allen, D.H.; Hurtado, L.D.; Helms, K.L.E.

    1995-03-01

    A thermomechanical analysis of a continuous fiber metal matrix composite (MMC) subjected to cyclic loading is performed herein. The analysis includes the effects of processing induced residual thermal stresses, matrix inelasticity, and interface cracking. Due to these complexities, the analysis is performed computationally using the finite element method. Matrix inelasticity is modelled with a rate dependent viscoplasticity model. Interface fracture is modelled by the use of a nonlinear interface constitutive model. The problem formulation is summarized, and results are given for a four-ply unidirectional SCS-6/{beta}21S titanium composite under high temperature isothermal mechanical fatigue. Results indicate rate dependent viscoplasticity can be a significant mechanism for dissipating the energy available for damage propagation, thus contributing to improved ductility of the composite. Results also indicate that the model may be useful for inclusion in life prediction methodologies for MMC`s.

  12. Strain Accumulation and Damage Evolution During Creep of SiCf/SiC Composites

    NASA Astrophysics Data System (ADS)

    Wilshire, Brian; Burt, Howard

    For many high-performance applications, worldwide research efforts continue to be focussed on ceramic-fibre-reinforced ceramic-matrix composites (CFCMCs), with numerous studies featuring SiC-fibre-reinforced SiC-matrix materials (termed SiCf/SiC type products). In particular, because these CFCMCs are being considered for components which must operate for long periods without failure under load in hostile high-temperature environments, special attention has then been directed to characterization of their creep and creep fracture behaviour. In turn, many of these studies have been concerned with clarification of the damage processes which cause creep failure, aiming to acquire the understanding needed for future product development and component design.

  13. Damage Evolution in Al Wire Bonds Subjected to a Junction Temperature Fluctuation of 30 K

    NASA Astrophysics Data System (ADS)

    Agyakwa, Pearl A.; Yang, Li; Arjmand, Elaheh; Evans, Paul; Corfield, Martin R.; Johnson, C. Mark

    2016-04-01

    Ultrasonically bonded heavy Al wires subjected to a small junction temperature fluctuation under power cycling from 40°C to 70°C were investigated using a non-destructive three-dimensional (3-D) x-ray tomography evaluation approach. The occurrence of irreversible deformation of the microstructure and wear-out under such conditions were demonstrated. The observed microstructures consist of interfacial and inter-granular cracks concentrated in zones of stress intensity, i.e., near heels and emanating from interface precracks. Interfacial voids were also observed within the bond interior. Degradation rates of `first' and `stitch' bonds are compared and contrasted. A correlative microscopy study combining perspectives from optical microscopy with the x-ray tomography results clarifies the damage observed. An estimation of lifetime is made from the results and discussed in the light of existing predictions.

  14. An explicit finite element formulation for dynamic strain localization and damage evolution in metals

    SciTech Connect

    Mourad, Hashem M; Bronkhorst, Curt A; Addessio, Francis L

    2010-12-16

    An explicit finite element formulation, used to study the behavior and failure mechanisms of metallic materials under high strain rate loading, is presented. The formulation is based on the assumed-strain approach of Fish and Belytschko [1988], which allows localization bands to be embedded within an element, thereby alleviating mesh sensitivity and reducing the required computational effort. The behavior of the material outside localization bands (and of the virgin material prior to the onset of strain localization) is represented using a Gurson-type coupled plasticity-damage model based on the work of Johnson and Addessio [1988]. Assuming adiabatic conditions, the response of the localization band material is represented by a set of constitutive equations for large elasticviscoplastic deformations in metals at high strain rates and high homologous temperatures (see Brown et al. [1989]). Computational results are compared to experimental data for different metallic alloys to illustrate the advantages of the proposed modeling strategy.

  15. Evolution.

    ERIC Educational Resources Information Center

    Mayr, Ernst

    1978-01-01

    Traces the history of evolution theory from Lamarck and Darwin to the present. Discusses natural selection in detail. Suggests that, besides biological evolution, there is also a cultural evolution which is more rapid than the former. (MA)

  16. Civil Law Glossary.

    ERIC Educational Resources Information Center

    Update on Law-Related Education, 1997

    1997-01-01

    Presents a glossary of civil law terms originally compiled for journalists by the American Bar Association. Defines many essential civil law concepts and practices including compensatory damages, jurisdiction, motion to dismiss, discovery, and remedy. (MJP)

  17. THEORETICAL INVESTIGATION OF MICROSTRUCTURE EVOLUTION AND DEFORMATION OF ZIRCONIUM UNDER CASCADE DAMAGE CONDITIONS

    SciTech Connect

    Barashev, Alexander V; Golubov, Stanislav I; Stoller, Roger E

    2012-06-01

    This work is based on our reaction-diffusion model of radiation growth of Zr-based materials proposed recently in [1]. In [1], the equations for the strain rates in unloaded pure crystal under cascade damage conditions of, e.g., neutron or heavy-ion irradiation were derived as functions of dislocation densities, which include contributions from dislocation loops, and spatial distribution of their Burgers vectors. The model takes into account the intra-cascade clustering of self-interstitial atoms and their one-dimensional diffusion; explains the growth stages, including the break-away growth of pre-annealed samples; and accounts for some striking observations, such as of negative strain in prismatic direction, and co-existence of vacancy- and interstitial-type prismatic loops. In this report, the change of dislocation densities due to accumulation of sessile dislocation loops is taken into account explicitly to investigate the dose dependence of radiation growth. The dose dependence of climb rates of dislocations is calculated, which is important for the climb-induced glide model of radiation creep. The results of fitting the model to available experimental data and some numerical calculations of the strain behavior of Zr for different initial dislocation structures are presented and discussed. The computer code RIMD-ZR.V1 (Radiation Induced Microstructure and Deformation of Zr) developed is described and attached to this report.

  18. Acoustic and Ultrasonic Spectral Evolution in Pre- and Post-Damage Self-Healing Poly (Ethylene Co-Methacrylic Acid) Ionomer Samples

    NASA Astrophysics Data System (ADS)

    Buckley, Jonathan; Pestka, Kenneth, II; Kalista, Stephen

    We measured the pre- and post-damage resonant spectra of several self-healing ionomer samples composed of poly (ethylene co-methacrylic acid) (EMAA). The post-damage results indicate significant time-dependent variation in the acoustic and ultrasonic resonant spectral waveforms of these self-healing samples. These results are consistent with other recent experiments that demonstrate time evolution of resonant frequencies and associated quality factors within samples of post-damage EMAA ionomers. However, in our experiments it was found that, in some circumstances, the quality factors and associated resonant frequencies can exhibit time-dependent variation both before and after external damage. By quantifying time-dependent variations in the spectra of undamaged samples, including quality factor, resonant frequency and spectral waveform, we demonstrate a method to isolate changes in the resonant spectra that are present solely due to the post-damage healing behavior of these EMAA ionomers.

  19. Adaptive Response to DNA-Damaging Agents in Natural Saccharomyces cerevisiae Populations from “Evolution Canyon”, Mt. Carmel, Israel

    PubMed Central

    Lidzbarsky, Gabriel A.; Shkolnik, Tamar; Nevo, Eviatar

    2009-01-01

    Background Natural populations of most organisms, especially unicellular microorganisms, are constantly exposed to harsh environmental factors which affect their growth. UV radiation is one of the most important physical parameters which influences yeast growth in nature. Here we used 46 natural strains of Saccharomyces cerevisiae isolated from several natural populations at the “Evolution Canyon” microsite (Nahal Oren, Mt. Carmel, Israel). The opposing slopes of this canyon share the same geology, soil, and macroclimate, but they differ in microclimatic conditions. The interslope differences in solar radiation (200%–800% more on the “African” slope) caused the development of two distinct biomes. The south-facing slope is sunnier and has xeric, savannoid “African” environment while the north-facing slope is represented by temperate, “European” forested environment. Here we studied the phenotypic response of the S. cerevisiae strains to UVA and UVC radiations and to methyl methanesulfonate (MMS) in order to evaluate the interslope effect on the strains' ability to withstand DNA-damaging agents. Methodology/Principal Findings We exposed our strains to the different DNA-damaging agents and measured survival by counting colony forming units. The strains from the “African” slope were more resilient to both UVA and MMS than the strains from the “European” slope. In contrast, we found that there was almost no difference between strains (with similar ploidy) from the opposite slopes, in their sensitivity to UVC radiation. These results suggest that the “African” strains are more adapted to higher solar radiation than the “European” strains. We also found that the tetraploids strains were more tolerant to all DNA-damaging agents than their neighboring diploid strains, which suggest that high ploidy level might be a mechanism of adaptation to high solar radiation. Conclusions/Significance Our results and the results of parallel studies with several other organisms, suggest that natural selection appears to select, at a microscale, for adaptive complexes that can tolerate the higher UV radiation on the “African” slope. PMID:19526052

  20. Dynamic damage model of crevasse opening and application to glacier calving

    NASA Astrophysics Data System (ADS)

    Pralong, A.; Funk, M.

    2005-01-01

    Theory and applications of continuum damage mechanics for ice are discussed, and on this basis, an ice damage model, valid at low stresses, is proposed. The model describes the damage itself, the rheology of the damaged ice, and the damage evolution. A local damaging and healing law is considered, and its parameterization is motivated. The model parameters are inferred from published data of laboratory experiments. The model is subsequently implemented in a finite element code and applied to the prediction of a calving process and to the destabilization of an ice chunk from a hanging glacier. Numerical results show good agreement with field measurements.

  1. Damage-induced nonassociated inelastic flow in rock salt

    SciTech Connect

    Chan, K.S.; Bodner, S.R.; Brodsky, N.S.; Fossum, A.F.

    1993-06-01

    The multi-mechanism deformation coupled fracture model recently developed by CHAN, et al. (1992), for describing time-dependent, pressure-sensitive inelastic flow and damage evolution in crystalline solids was evaluated against triaxial creep experiments on rock salt. Guided by experimental observations, the kinetic equation and the flow law for damage-induced inelastic flow in the model were modified to account for the development of damage and inelastic dilatation in the transient creep regime. The revised model was then utilized to obtain the creep response and damage evolution in rock salt as a function of confining pressure and stress difference. Comparison between model calculation and experiment revealed that damage-induced inelastic flow is nonassociated, dilatational, and contributes significantly to the macroscopic strain rate observed in rock salt deformed at low confining pressures. The inelastic strain rate and volumetric strain due to damage decrease with increasing confining pressures, and all are suppressed at sufficiently high confining pressures.

  2. Modeling Damage Growth in Oxidized High-Temperature Polymeric Composites

    NASA Astrophysics Data System (ADS)

    An, Nan; Pochiraju, Kishore

    2013-02-01

    Thermal oxidation is a major degradation mechanism for polymers and composites operating at high temperatures. Controlling the damage progression in oxidative environments is critical for enhancing the long-term durability of these materials. The surface oxidation of the material and the damage evolution in high-temperature polymer matrix composite materials (HTPMCs) are highly coupled mechanisms. In this article, three-dimensional, finite-element methods are used to simulate both oxidation layer and damage growth in polymers subjected to bending loads and laminated composites subjected to uniaxial tension. An oxygen diffusion-reaction model determines the changes in properties due to oxidation and chemical strains induced by oxidation. The damage growth is simulated using mesh-free extended finite-element techniques and suitable damage initiation laws. The damage evolution observed with simulations is seen to be consistent with experimental observations reported in the literature.

  3. An investigation of the effects of history dependent damage in time dependent fracture mechanics: nano-scale studies of damage evolution

    SciTech Connect

    Brust, F.W. Jr; Mohan, R.; Yang, Y.P.; Oh, J.; Katsube, N.

    2002-12-01

    High-temperature operation of technical engineering systems is critical for system efficiency, and will be a key driver in the future US DOE energy policy. Developing an understanding of high-temperature creep and creep-fatigue failure processes is a key driver for the research work described here. The focus is on understanding the high-temperature deformation and damage development on the nano-scale (50 to 500 nm) level. The high-temperature damage development process, especially with regard to low and high cyclic loading, which has received little attention to date, is studied. Damage development under cyclic loading develops in a fashion quite different from the constant load situation. The development of analytical methodologies so that high-temperature management of new systems can be realized is the key goal of this work.

  4. A Description Of Crevasse Formation Using Continuum Damage Mechanics

    NASA Astrophysics Data System (ADS)

    Pralong, A.; Funk, M.; Luethi, M. P.

    2003-12-01

    Continuum damage mechanics describes the progressive deterioration of material subjected to loading. For polycrystalline ice, a local isotropic damage evolution law coupled to Glen's flow law allows the description of creep to failure. The damage evolution law has been derived from mesoscopic tests performed in traction and shearing. Damage initiation is controlled by a size dependent stress threshold, which has been inferred from published data of laboratory experiments. Crack healing is considered by a simple dynamic law. The rheology of the damaged ice is implemented in a FE model to describe the formation of crevasses at a macroscopic scale. A level set method is applied to model the evolution of the glacier geometry. The main purpose of this investigation is the modelling of the destabilization of large ice masses from hanging glaciers. The rupture of large ice chunks has been computed for different hanging glaciers in Switzerland. Numerical results compared with field observations and measurements showed good agreement. The ability of the model to describe phenomena connected to crevasse opening seems to be promising for other glaciological applications such as rift opening or ice stream margin formation.

  5. A damage analysis for brittle materials using stochastic micro-structural information

    NASA Astrophysics Data System (ADS)

    Lin, Shih-Po; Chen, Jiun-Shyan; Liang, Shixue

    2016-01-01

    In this work, a micro-crack informed stochastic damage analysis is performed to consider the failures of material with stochastic microstructure. The derivation of the damage evolution law is based on the Helmholtz free energy equivalence between cracked microstructure and homogenized continuum. The damage model is constructed under the stochastic representative volume element (SRVE) framework. The characteristics of SRVE used in the construction of the stochastic damage model have been investigated based on the principle of the minimum potential energy. The mesh dependency issue has been addressed by introducing a scaling law into the damage evolution equation. The proposed methods are then validated through the comparison between numerical simulations and experimental observations of a high strength concrete. It is observed that the standard deviation of porosity in the microstructures has stronger effect on the damage states and the peak stresses than its effect on the Young's and shear moduli in the macro-scale responses.

  6. A damage analysis for brittle materials using stochastic micro-structural information

    NASA Astrophysics Data System (ADS)

    Lin, Shih-Po; Chen, Jiun-Shyan; Liang, Shixue

    2016-03-01

    In this work, a micro-crack informed stochastic damage analysis is performed to consider the failures of material with stochastic microstructure. The derivation of the damage evolution law is based on the Helmholtz free energy equivalence between cracked microstructure and homogenized continuum. The damage model is constructed under the stochastic representative volume element (SRVE) framework. The characteristics of SRVE used in the construction of the stochastic damage model have been investigated based on the principle of the minimum potential energy. The mesh dependency issue has been addressed by introducing a scaling law into the damage evolution equation. The proposed methods are then validated through the comparison between numerical simulations and experimental observations of a high strength concrete. It is observed that the standard deviation of porosity in the microstructures has stronger effect on the damage states and the peak stresses than its effect on the Young's and shear moduli in the macro-scale responses.

  7. The effects of shockwave profile shape and shock obliquity on spallation : studies of kinetics and stress state effects on damage evolution

    SciTech Connect

    Gray, George T., III; Hull, Larry M; Faulkner, J R; Briggs, M E; Cerreta, E K; Addessio, F L; Bourne, N K

    2009-06-22

    Shock-loading of a material in contact with a high explosive (HE) experiences a 'Taylor wave' (triangular wave) loading profile in contrast to the square-wave loading profile imparted via the impact of a flyer plate. Detailed metallographic and mlcrotextural analysis of the damage evolution in spalled Cu samples as a function of square/triangle and sweeping detonation-wave loading is presented.

  8. Brittle Creep, Damage and Time to Failure in Rocks

    NASA Astrophysics Data System (ADS)

    Amitrano, D.; Helmstetter, A.

    2005-12-01

    We first review published data of time to failure, t_f, of rocks under creep conditions. We compare exponential and power-law relationship between t_f and the applied stress for tests performed on different types of rock and various environmental conditions. This data shows that the time to failure changes by several orders of magnitude when varying the confining pressure, the temperature or the water saturation. We then use this time-to-failure relation as input for a numerical model based on progressive damage. This model reproduces the primary and tertiary creep regimes observed experimentally for rocks. During primary creep, the strain rate, the energy rate, and the rate of damage events decay with time as a power-law with an exponent of 0.8. The tertiary creep is characterized by a power-law acceleration of damage with an exponent of 0.8 for the event rate, and 1.3 for strain and energy rates. We derive analytical solutions for a simplified version of the model, which explain qualitatively these results. The distribution of damage event sizes is a power law when integrated over all the simulation. The temporal evolution of this distribution shows an increase of the mean event size before failure. During primary creep, damage is relatively uniform in space. Damage localization occurs at the transition between primary and tertiary creep, when damage rate starts accelerating. The final state of the simulation shows highly damaged bands, similar to shear bands observed during laboratory experiments. The thickness and the orientation of these bands depend on the applied stress. This model shows that a complex global behavior (primary and tertiary creep regimes, power-law distribution of event sizes, and damage localization) can emerge from a simple elementary behavior, based on progressive damage and experimentally established time-to-failure law.

  9. Influence of sweeping detonation-wave loading on damage evolution during spallation loading of tantalum in both a planar and curved geometry

    SciTech Connect

    Gray, George Thompson III; Hull, Lawrence Mark; Livescu, Veronica; Faulkner, James; Briggs, Matthew E.; Meyer, Ross Keith; Andrews, Heather Lynn; Hare, Steven John; Jakulewicz, Micah Shawn; Shinas, Michael A.

    2015-03-30

    Widespread research over the past five decades has provided a wealth of experimental data and insight concerning the shock hardening, damage evolution, and the spallation response of materials subjected to square-topped shock-wave loading profiles. However, fewer quantitative studies have been conducted on the effect of direct, in-contact, high explosive (HE)-driven Taylor wave (unsupported shocks) loading on the shock hardening, damage evolution, or spallation response of materials. Systematic studies quantifying the effect of sweeping-detonation wave loading are yet sparser. In this study, the damage evolution and spallation response of Ta is shown to be critically dependent on the peak shock stress, the geometry of the sample (flat or curved plate geometry), and the shock obliquity during sweeping-detonation-wave shock loading. Sweepingwave loading in the flat-plate geometry is observed to: a) yield a lower spall strength than previously documented for 1-D supported-shock-wave loading, b) exhibit increased shock hardening as a function of increasing obliquity, and c) lead to an increased incidence of deformation twin formation with increasing shock obliquity. Sweeping-wave loading of a 10 cm radius curved Ta plate is observed to: a) lead to an increase in the shear stress as a function of increasing obliquity, b) display a more developed level of damage evolution, extensive voids and coalescence, and lower spall strength with obliquity in the curved plate than seen in the flat-plate sweeping-detonation wave loading for an equivalent HE loading, and c) no increased propensity for deformation twin formation with increasing obliquity as seen in the flat-plate geometry. The overall observations comparing and contrasting the flat versus curved sweeping-wave spall experiments with 1D loaded spallation behavior suggests a coupled influence of obliquity and geometry on dynamic shock-induced damage evolution and spall strength. Coupled experimental and modeling research to quantify the combined effects of sweeping-wave loading with increasingly complex sample geometries on the shockwave response of materials is clearly crucial to providing the basis for developing and thereafter validation of predictive modeling capability.

  10. Farmers, Ranchers, and the Railroad: The Evolution of Fence Law in the Great Plains, 1865-1900

    ERIC Educational Resources Information Center

    Kawashima, Yasuhide

    2010-01-01

    This article is divided into three parts. The first examines specific fencing policies in Kansas, Nebraska, and other Plains states, highlighting the transformation from the "fence-out" to "fence-in" (herd laws) policies. The second part discusses the coming of the railroads to the Great Plains and the farmers and the ranchers as beneficiaries who…

  11. Development of a viscoelastic continuum damage model for cyclic loading

    NASA Astrophysics Data System (ADS)

    Sullivan, R. W.

    2008-12-01

    A previously developed spectrum model for linear viscoelastic behavior of solids is used to describe the rate-dependent damage growth of a time dependent material under cyclic loading. Through the use of the iterative solution of a special Volterra integral equation, the cyclic strain history is described. The spectrum-based model is generalized for any strain rate and any uniaxial load history to formulate the damage function. Damage evolution in the body is described through the use of a rate-type evolution law which uses a pseudo strain to express the viscoelastic constitutive equation with damage. The resulting damage function is used to formulate a residual strength model. The methodology presented is demonstrated by comparing the peak values of the computed cyclic strain history as well as the residual strength model predictions to the experimental data of a polymer matrix composite.

  12. Propagation of continuum damage in a viscoelastic ice bar

    SciTech Connect

    Shin, J.G. . Dept. of Naval Architecture and Ocean Engineering); Karr, D.G. . Dept. of Naval Architecture and Marine Engineering)

    1994-05-01

    An initial value problem of a semi-infinite nonlinear viscoelastic bar is solved with continuum damage evolution. The evolution law of the continuum damage for a viscoelastic material is used in order to explore the propagation of two crushing mechanisms: grain boundary cracking and transgranular cracking. Using the method of characteristics, the speed of propagation is found to be dependent on the continuum damage. On the wave front, the delayed elastic strain is zero, and only the continuum damage due to the transgranular cracking evolves. A finite difference method is developed to solve the governing equations on the obtained characteristic lines, and gives a stable solution for the propagation of the stress, strain, and damage. Numerical results are obtained and discussed using the material properties of polycrystalline ice.

  13. Equilibrium configurations and stability of a damaged body under uniaxial tractions

    NASA Astrophysics Data System (ADS)

    Lanzoni, Luca; Tarantino, Angelo Marcello

    2015-02-01

    This paper deals with the equilibrium problem in nonlinear dissipative inelasticity of damaged bodies subject to uniaxial loading. To model the damage effects, a damage function, affecting the stored energy function, is defined. In the framework of the continuum thermodynamics theory, the constitutive law for damaged hyperelastic materials and an inequality for the energy release rate are derived. By means of an energy-based damage criterion, the irreversible evolution law for the damage function is obtained. After formulating the equilibrium boundary value problem, explicit expressions governing the global development of the equilibrium paths are written. Successively, the stability of the equilibrium solutions are assessed through the energy criterion. For a damaged body under uniaxial loading, seven inequalities are derived. These conditions, if fulfilled, ensure the stability of the solutions under each type of small perturbation. Finally, a number of applications for compressible neo-Hookean and Mooney-Rivlin materials are performed.

  14. Comparison of Tensile Damage Evolution in Ti6A14V Joints Between Laser Beam Welding and Gas Tungsten Arc Welding

    NASA Astrophysics Data System (ADS)

    Gao, Xiao-Long; Zhang, Lin-Jie; Liu, Jing; Zhang, Jian-Xun

    2014-09-01

    The present paper studied the evolution of tensile damage in joints welded using laser beam welding (LBW) and gas tungsten arc welding (TIG) under a uniaxial tensile load. The damage evolution in the LBW joints and TIG-welded joints was studied by using digital image correlation (DIC) technology and monitoring changes in Young's modulus during tensile testing. To study the mechanism of void nucleation and growth in the LBW joints and TIG-welded joints, test specimens with various amounts of plastic deformation were analyzed using a scanning electron microscope (SEM). Compared with TIG-welded joints, LBW-welded joints have a finer microstructure and higher microhardness in the fusion zone. The SEM analysis and DIC test results indicated that the critical strain of void nucleation was greater in the LBW-welded joints than in the TIG-welded joints, while the growth rate of voids was lower in the LBW-welded joints than in the TIG-welded joints. Thus, the damage ratio in the LBW joints was lower than that in the TIG-welded joints during tensile testing. This can be due to the coarser martensitic α' and the application of TC-1 welding rods in the TIG-welded joint.

  15. Comparison of Tensile Damage Evolution in Ti6A14V Joints Between Laser Beam Welding and Gas Tungsten Arc Welding

    NASA Astrophysics Data System (ADS)

    Gao, Xiao-Long; Zhang, Lin-Jie; Liu, Jing; Zhang, Jian-Xun

    2014-12-01

    The present paper studied the evolution of tensile damage in joints welded using laser beam welding (LBW) and gas tungsten arc welding (TIG) under a uniaxial tensile load. The damage evolution in the LBW joints and TIG-welded joints was studied by using digital image correlation (DIC) technology and monitoring changes in Young's modulus during tensile testing. To study the mechanism of void nucleation and growth in the LBW joints and TIG-welded joints, test specimens with various amounts of plastic deformation were analyzed using a scanning electron microscope (SEM). Compared with TIG-welded joints, LBW-welded joints have a finer microstructure and higher microhardness in the fusion zone. The SEM analysis and DIC test results indicated that the critical strain of void nucleation was greater in the LBW-welded joints than in the TIG-welded joints, while the growth rate of voids was lower in the LBW-welded joints than in the TIG-welded joints. Thus, the damage ratio in the LBW joints was lower than that in the TIG-welded joints during tensile testing. This can be due to the coarser martensitic α' and the application of TC-1 welding rods in the TIG-welded joint.

  16. Evolution of patients' complaints in a French university hospital: is there a contribution of a law regarding patients' rights?

    PubMed Central

    Giugliani, Camila; Gault, Nathalie; Fares, Valia; Jegu, Jérémie; Trolli, Sergio Eleni dit; Biga, Julie; Vidal-Trecan, Gwenaelle

    2009-01-01

    Background Legislative measures have been identified as one effective way of changing attitude or behaviour towards health care. The aim of this study was to describe trends in patients' complaints for medical issues; to evaluate the contribution of a law regarding patients' rights, and to identify factors associated to patients' perception of a medical error. Methods Patients with a complaint letter for medical issues in a French university hospital were included. Trends in complaint rates were analysed. Comparisons were made between a first (1998–2000) and a second (2001–2004) time period, before and after the diffusion of the law, and according to the perception of a medical error. Results Complaints for medical issues increased from 1998 to 2004. Of 164 complaints analysed, 66% were motivated by the perception of a medical error (47% during the first time period vs. 73% during the second time period; p = 0.001). Error or delay in diagnosis/treatment and surgical/medical complication were the main reasons for complaints. Surgical departments had the higher number of complaints. Second time period, substandard care, disability, and adverse effect of a health product were independently associated with the perception of a medical error, positively for the formers, and negatively for the latter. Conclusion This study revealed an increase with time in the number of complaints for medical issues in a university hospital, as well as an increase in the perception of a medical error after the passing of a law regarding patients' rights in France. PMID:19660131

  17. Evolution

    NASA Astrophysics Data System (ADS)

    Peter, Ulmschneider

    When we are looking for intelligent life outside the Earth, there is a fundamental question: Assuming that life has formed on an extraterrestrial planet, will it also develop toward intelligence? As this is hotly debated, we will now describe the development of life on Earth in more detail in order to show that there are good reasons why evolution should culminate in intelligent beings.

  18. Integrability and conservation laws for the nonlinear evolution equations of partially coherent waves in noninstantaneous Kerr media.

    PubMed

    Hansson, T; Lisak, M; Anderson, D

    2012-02-10

    It is shown that the evolution equations describing partially coherent wave propagation in noninstantaneous Kerr media are integrable and have an infinite number of invariants. A recursion relation for generating these invariants is presented, and it is demonstrated how to express them in the coherent density, self-consistent multimode, mutual coherence, and Wigner formalisms. PMID:22401072

  19. Spatial evolution of the helical behavior and the 2/3 power-law in single-square-grid-generated turbulence

    NASA Astrophysics Data System (ADS)

    Zhou, Yi; Nagata, Kouji; Sakai, Yasuhiko; Ito, Yasumasa; Hayase, Toshiyuki

    2016-04-01

    Direct numerical simulations are performed to investigate the helical properties of single-square-grid-generated turbulence. The streamwise evolution of the probability density functions of the relative helicity density h reveals the existence of a transition from a quasi-two-dimensional state to a three-dimensional state. The correlations between the helicity and the enstrophy level as well as the dissipation level are examined. When conditioned on a high level of dissipation or enstrophy, in the energy decay region the velocity and vorticity vectors in both instantaneous and fluctuating fields become more aligned. However, this correlation does not hold in the production region. We also study the second-order structure function and reveal that a well-defined 2/3 power-law can be found at a location quite close to the grid, where the turbulent flow is still in the transition state.

  20. Postbuckling Investigations of Piezoelectric Microdevices Considering Damage Effects

    PubMed Central

    Sun, Zhigang; Wang, Xianqiao

    2014-01-01

    Piezoelectric material has been emerging as a popular building block in MEMS devices owing to its unique mechanical and electrical material properties. However, the reliability of MEMS devices under buckling deformation environments remains elusive and needs to be further explored. Based on the Talreja's tensor valued internal state damage variables as well as the Helmhotlz free energy of piezoelectric material, a constitutive model of piezoelectric materials with damage is presented. The Kachanvo damage evolution law under in-plane compressive loads is employed. The model is applied to the specific case of the postbuckling analysis of the piezoelectric plate with damage. Then, adopting von Karman's plate theory, the nonlinear governing equations of the piezoelectric plates with initial geometric deflection including damage effects under in-plane compressive loads are established. By using the finite difference method and the Newmark scheme, the damage evolution for damage accumulation is developed and the finite difference procedure for postbuckling equilibrium path is simultaneously employed. Numerical results show the postbuckling behaviors of initial flat and deflected piezoelectric plates with damage or no damage under different sets of electrical loading conditions. The effects of applied voltage, aspect ratio of plate, thick-span ratio of plate, damage as well as initial geometric deflections on the postbuckling behaviors of the piezoelectric plate are discussed. PMID:24618774

  1. Postbuckling investigations of piezoelectric microdevices considering damage effects.

    PubMed

    Sun, Zhigang; Wang, Xianqiao

    2014-01-01

    Piezoelectric material has been emerging as a popular building block in MEMS devices owing to its unique mechanical and electrical material properties. However, the reliability of MEMS devices under buckling deformation environments remains elusive and needs to be further explored. Based on the Talreja's tensor valued internal state damage variables as well as the Helmhotlz free energy of piezoelectric material, a constitutive model of piezoelectric materials with damage is presented. The Kachanvo damage evolution law under in-plane compressive loads is employed. The model is applied to the specific case of the postbuckling analysis of the piezoelectric plate with damage. Then, adopting von Karman's plate theory, the nonlinear governing equations of the piezoelectric plates with initial geometric deflection including damage effects under in-plane compressive loads are established. By using the finite difference method and the Newmark scheme, the damage evolution for damage accumulation is developed and the finite difference procedure for postbuckling equilibrium path is simultaneously employed. Numerical results show the postbuckling behaviors of initial flat and deflected piezoelectric plates with damage or no damage under different sets of electrical loading conditions. The effects of applied voltage, aspect ratio of plate, thick-span ratio of plate, damage as well as initial geometric deflections on the postbuckling behaviors of the piezoelectric plate are discussed. PMID:24618774

  2. Application of Phase Space Warping on Damage Tracking for Bearing Fault

    NASA Astrophysics Data System (ADS)

    Fan, Bin; Hu, Niaoqing; Hu, Lei; Gu, Fengshou

    2012-05-01

    Nowadays, the significance of keeping equipment function properly each time is obvious. If equipment fails during its use, it may have disastrous consequences. Estimating remaining useful life (RUL) of equipment is a key to prevent such calamities, improve its reliability, provide security and reduce unnecessary maintenance and operational cost. The evolution and tracking of damage is the foundation of RUL predicting, and also is one of the most important content of mechanical fault diagnosis. Slow-time variable process of mechanical damage would lead the phase space reconstructed by fast-time variable vibrate signals warping. Search the dynamics characteristic law of damage evolution analysis in the phase space, and build the relationship between fast-time variable signals and slow-time variable damage, and then damage evolution tracking is possible. To validate the theory, simulation model of bearing damage evolution is built, the outer-race fault evolution signals is obtained, and the trend of evolution of degradation of bearing fault is described with Phase Space Warping (PSW) theory and Smooth Orthogonal Decomposition (SOD). The results proved the feasibility of the methodology of PSW in damage evolution tracking.

  3. Selective neuronal vulnerability of human hippocampal CA1 neurons: lesion evolution, temporal course, and pattern of hippocampal damage in diffusion-weighted MR imaging.

    PubMed

    Bartsch, Thorsten; Döhring, Juliane; Reuter, Sigrid; Finke, Carsten; Rohr, Axel; Brauer, Henriette; Deuschl, Günther; Jansen, Olav

    2015-11-01

    The CA1 (cornu ammonis) region of hippocampus is selectively vulnerable to a variety of metabolic and cytotoxic insults, which is mirrored in a delayed neuronal death of CA1 neurons. The basis and mechanisms of this regional susceptibility of CA1 neurons are poorly understood, and the correlates in human diseases affecting the hippocampus are not clear. Adopting a translational approach, the lesion evolution, temporal course, pattern of diffusion changes, and damage in hippocampal CA1 in acute neurologic disorders were studied using high-resolution magnetic resonance imaging. In patients with hippocampal ischemia (n=50), limbic encephalitis (n=30), after status epilepticus (n=17), and transient global amnesia (n=53), the CA1 region was selectively affected compared with other CA regions of the hippocampus. CA1 neurons exhibited a maximum decrease of apparent diffusion coefficient (ADC) 48 to 72 hours after the insult, irrespective of the nature of the insult. Hypoxic-ischemic insults led to a significant lower ADC suggesting that the ischemic insult results in a stronger impairment of cellular metabolism. The evolution of diffusion changes show that CA1 diffusion lesions mirror the delayed time course of the pathophysiologic cascade typically observed in animal models. Studying the imaging correlates of hippocampal damage in humans provides valuable insight into the pathophysiology and neurobiology of the hippocampus. PMID:26082014

  4. Implications of the Power Law Cutoff Evolution in XTE J1550-564 to the Comptonization Regimes

    NASA Astrophysics Data System (ADS)

    Shaposhnikov, Nikolai; Titarchuk, L.

    2010-05-01

    We present spectral analysis of data collected using RXTE during two periods of X-ray activity in 1998 and 2000 from the Galactic X-ray black hole binary XTE J1550-564. We particularly concentrate on the behavior of the high energy cutoff (folding energy) of the power law part of the spectrum. The 1998 event was very powerful, showing a quick initial transition from low-hard state to very high state. The power law cutoff energy decreased from low-hard to intermediate states and increased again during transition to very high and high-soft states. For the 2000 outburst we also observe the decrease of the cutoff energy during the start of the state transition, similar to that in 1998 outburst, however the increase of the high energy cutoff is not apparent in this track because the source does not reach the real high-soft state in this event. We attribute this difference in the cutoff energy behavior to the different partial contributions of the thermal and non-thermal (bulk motion) Comptonization in photon upscattering. Namely, during the 1998 event higher accretion rate presumably provided more cooling to the Comptonizing media and thus reducing the effectiveness of the thermal upscattering process. Under these conditions the bulk motion should take a leading role in boosting the input soft photons. This observational behavior of the cutoff energy presents an additional evidence of the existence of the converging bulk motion region near the central objects and provides further support for the previously reported index saturations effect as a black hole signature.

  5. Damage characterization for particles filled semi-crystalline polymer

    NASA Astrophysics Data System (ADS)

    Lauro, Franck; Balieu, Romain; Bennani, Bruno; Haugou, Gregory; Bourel, Benjamin; Chaari, Fahmi; Matsumoto, Tsukatada; Mottola, Ernesto

    2015-09-01

    Damage evolution and characterization in semi-crystalline polymer filled with particles under various loadings is still a challenge. A specific damage characterization method using Digital Image Correlation is proposed for a wide range of strain rates considering tensile tests with hydraulic jacks as well as Hopkinson's bars. This damage measurement is obtained by using and adapting the SEE method [1] which was developed to characterize the behaviour laws at constant strain rates of polymeric materials in dynamic. To validate the characterization process, various damage measurement techniques are used under quasi-static conditions before to apply the procedure in dynamic. So, the well-known damage characterization by loss of stiffness technique under quasi-static loading is applied to a polypropylene. In addition, an in-situ tensile test, carried out in a microtomograph, is used to observe the cavitation phenomenon in real time. A good correlation is obtained between all these techniques and consequently the proposed technique is supposed suitable for measuring the ductile damage observed in semi-crystalline polymers under dynamic loading. By applying it to the semi-crystalline polymer at moderate and high speed loadings, the damage evolution is measured and it is observed that the damage evolution is not strain rate dependent but the failure strain on the contrary is strain rate dependent.

  6. Simultaneous Tomography and Diffraction Analysis of Creep Damage

    NASA Astrophysics Data System (ADS)

    Pyzalla, A.; Camin, B.; Buslaps, T.; Di Michiel, M.; Kaminski, H.; Kottar, A.; Pernack, A.; Reimers, W.

    2005-04-01

    Creep damage by void nucleation and growth limits the lifetime of components subjected to loading at high temperatures. We report a combined tomography and diffraction experiment using high-energy synchrotron radiation that permitted us to follow in situ void growth and microstructure development in bulk samples. The results reveal that void growth versus time follows an exponential growth law. The formation of large void volumes coincides with texture evolution and dislocation density, reaching a steady state. Creep damage during a large proportion of sample creep life is homogeneous before damage localization occurs, which leads to rapid failure. The in situ determination of void evolution in bulk samples should allow for the assessment of creep damage in metallic materials and subsequently for lifetime predictions about samples and components that are subject to high-temperature loading.

  7. Investigation of a Novel NDE Method for Monitoring Thermomechanical Damage and Microstructure Evolution in Ferritic-Martensitic Steels for Generation IV Nuclear Energy Systems

    SciTech Connect

    Nagy, Peter

    2013-09-30

    The main goal of the proposed project is the development of validated nondestructive evaluation (NDE) techniques for in situ monitoring of ferritic-martensitic steels like Grade 91 9Cr-1Mo, which are candidate materials for Generation IV nuclear energy structural components operating at temperatures up to ~650{degree}C and for steam-generator tubing for sodium-cooled fast reactors. Full assessment of thermomechanical damage requires a clear separation between thermally activated microstructural evolution and creep damage caused by simultaneous mechanical stress. Creep damage can be classified as "negligible" creep without significant plastic strain and "ordinary" creep of the primary, secondary, and tertiary kind that is accompanied by significant plastic deformation and/or cavity nucleation and growth. Under negligible creep conditions of interest in this project, minimal or no plastic strain occurs, and the accumulation of creep damage does not significantly reduce the fatigue life of a structural component so that low-temperature design rules, such as the ASME Section III, Subsection NB, can be applied with confidence. The proposed research project will utilize a multifaceted approach in which the feasibility of electrical conductivity and thermo-electric monitoring methods is researched and coupled with detailed post-thermal/creep exposure characterization of microstructural changes and damage processes using state-of-the-art electron microscopy techniques, with the aim of establishing the most effective nondestructive materials evaluation technique for particular degradation modes in high-temperature alloys that are candidates for use in the Next Generation Nuclear Plant (NGNP) as well as providing the necessary mechanism-based underpinnings for relating the two. Only techniques suitable for practical application in situ will be considered. As the project evolves and results accumulate, we will also study the use of this technique for monitoring other GEN IV materials. Through the results obtained from this integrated materials behavior and NDE study, new insight will be gained into the best nondestructive creep and microstructure monitoring methods for the particular mechanisms identified in these materials. The proposed project includes collaboration with a national laboratory partner and the results will also serve as a foundation to guide the efforts of scientists in the DOE laboratory, university, and industrial communities concerned with the technological challenges of monitoring creep and microstructural evolution in materials planned to be used in Generation IV Nuclear Energy Systems.

  8. 77 FR 31827 - Pipeline Safety: Pipeline Damage Prevention Programs

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-30

    ... Safety: Pipeline Damage Prevention Programs AGENCY: Pipeline and Hazardous Materials Safety... excavation damage prevention law enforcement programs; establish an administrative process for making... excavation damage prevention law enforcement programs; and establish the adjudication process...

  9. Experimental evaluation of a constitutive model for inelastic flow and damage evolution in solids subjected to triaxial compression

    SciTech Connect

    Fossum, A.F.; Brodsky, N.S.; Munson, D.E.

    1992-12-31

    Recent concern over the potential for creep induced development of a damaged rock zone adjacent to shafts and rooms at the Waste Isolation Pilot Plant (WIPP) has motivated the formulation of a coupled constitutive description of continuum salt creep and damage. This constitutive model gives time-dependent inelastic flow and pressure-sensitive damage in crystalline solids. Initially the constitutive model was successfully used to simulate multiaxial, i.e. true triaxial, experiments obtained at relatively high, 2.5 to 20 MPa, confining pressures. Predictions of the complete creep curve, including the heretofore unmodeled tertiary creep, were also demonstrated. However, comparisons of model predictions with data were hampered because the bulk of the creep data existing on WIPP salt was intentionally obtained under confining pressures typically greater than 15 MPa, in an attempt to match the underground in situ lithostatic pressure level. It was realized that the high confining pressures suppressed tertiary creep and resulted in better defined steady state creep responses. To address the tertiary creep process directly, a number of creep tests were conducted at lower confining pressures for the explicit purpose of creating dilatant behavior.

  10. Experimental evaluation of a constitutive model for inelastic flow and damage evolution in solids subjected to triaxial compression

    SciTech Connect

    Fossum, A.F.; Brodsky, N.S. ); Chan, K.S. ); Munson, D.E. )

    1992-01-01

    Recent concern over the potential for creep induced development of a damaged rock zone adjacent to shafts and rooms at the Waste Isolation Pilot Plant (WIPP) has motivated the formulation of a coupled constitutive description of continuum salt creep and damage. This constitutive model gives time-dependent inelastic flow and pressure-sensitive damage in crystalline solids. Initially the constitutive model was successfully used to simulate multiaxial, i.e. true triaxial, experiments obtained at relatively high, 2.5 to 20 MPa, confining pressures. Predictions of the complete creep curve, including the heretofore unmodeled tertiary creep, were also demonstrated. However, comparisons of model predictions with data were hampered because the bulk of the creep data existing on WIPP salt was intentionally obtained under confining pressures typically greater than 15 MPa, in an attempt to match the underground in situ lithostatic pressure level. It was realized that the high confining pressures suppressed tertiary creep and resulted in better defined steady state creep responses. To address the tertiary creep process directly, a number of creep tests were conducted at lower confining pressures for the explicit purpose of creating dilatant behavior.

  11. Pyrolytic carbon free-radical evolution and irradiation damage of polyimide under low-energy proton irradiation

    SciTech Connect

    Sun Chengyue; Wu Yiyong; Xiao Jingdong; Li Ruifeng; Yang Dezhuang; He Shiyu

    2011-12-15

    Ionization and displacement effects are basic phenomena in damage processes of materials under space-particle irradiation. In this paper, the damage behaviors were investigated on the polyimide under proton irradiation using electron paramagnetic resonance (EPR) spectra analysis and optical absorbance valuation. The results indicate that the proton irradiation induces the formation of pyrolytic carbon free-radical with a g value of 2.0025, and the population of free radicals increases with the irradiation fluence. The most important finding is that the irradiation-induced free-radical population increases linearly with the displacement damage dose, as does the optical degradation, whereas the ionization effect alone, during the irradiation, cannot induce the formation of pyrolytic carbon free radical. Furthermore, during the post storage, after irradiation, the free-radical population decreases following a sum of an exponential and a linear mode with the storage time. It is interesting that, during the post storage, the recovery of the degraded optical absorbance of the polyimide follows a similar mode to that of free radicals, and the characteristic time constant changes with the wavelength of the optical spectra.

  12. Effects of processing history on the evolution of surface damage layer and dislocation substructure in large grain niobium cavities

    NASA Astrophysics Data System (ADS)

    Kang, D.; Bieler, T. R.; Compton, C.

    2015-12-01

    Large grain niobium (Nb) is being investigated for fabricating superconducting radiofrequency cavities as an alternative to the traditional approach using fine grain polycrystalline Nb sheets. Past studies have identified a surface damage layer on fine grain cavities due to deep drawing and demonstrated the necessity for chemical etching on the surface. However, the origin of and depth of the damage layer are not well understood, and similar exploration on large grain cavities is lacking. In this work, electron backscatter diffraction (EBSD) was used to examine the cross sections at the equator and iris of a half cell deep drawn from a large grain Nb ingot slice. The results indicate that the damage (identified by a high density of geometrically necessary dislocations) depends on crystal orientations, is different at the equator and iris, and is present through the full thickness of a half cell in some places. After electron backscatter diffraction, the specimens were heat treated at 800 °C or 1000 °C for two hours, and the same areas were reexamined. A more dramatic decrease in dislocation content was observed at the iris than the equator, where some regions exhibited no change. The specimens were then etched and examined again, to determine if the subsurface region behaved differently than the surface. Little change in the dislocation substructure was observed, suggesting that the large grain microstructure is retained with a normal furnace anneal.

  13. Temperature activated absorption during laser-induced damage: The evolution of laser-supported solid-state absorption fronts

    SciTech Connect

    Carr, C W; Bude, J D; Shen, N; Demange, P

    2010-10-26

    Previously we have shown that the size of laser induced damage sites in both KDP and SiO{sub 2} is largely governed by the duration of the laser pulse which creates them. Here we present a model based on experiment and simulation that accounts for this behavior. Specifically, we show that solid-state laser-supported absorption fronts are generated during a damage event and that these fronts propagate at constant velocities for laser intensities up to 4 GW/cm{sup 2}. It is the constant absorption front velocity that leads to the dependence of laser damage site size on pulse duration. We show that these absorption fronts are driven principally by the temperature-activated deep sub band-gap optical absorptivity, free electron transport, and thermal diffusion in defect-free silica for temperatures up to 15,000K and pressures < 15GPa. In addition to the practical application of selecting an optimal laser for pre-initiation of large aperture optics, this work serves as a platform for understanding general laser-matter interactions in dielectrics under a variety of conditions.

  14. Evolution of different dual-use concepts in international and national law and its implications on research ethics and governance.

    PubMed

    Rath, Johannes; Ischi, Monique; Perkins, Dana

    2014-09-01

    This paper provides an overview of the various dual-use concepts applied in national and international non-proliferation and anti-terrorism legislation, such as the Biological and Toxin Weapons Convention, the Chemical Weapons Convention and United Nations Security Council Resolution 1540, and national export control legislation and in relevant codes of conduct. While there is a vast literature covering dual-use concepts in particular with regard to life sciences, this is the first paper that incorporates into such discussion the United Nations Security Council Resolution 1540. In addition, recent developments such as the extension of dual-use export control legislation in the area of human rights protection are also identified and reviewed. The discussion of dual-use concepts is hereby undertaken in the context of human- and/or national-security-based approaches to security. This paper discusses four main concepts of dual use as applied today in international and national law: civilian versus military, peaceful versus non-peaceful, legitimate versus illegitimate and benevolent versus malevolent. In addition, the usage of the term to describe positive technology spin-offs between civilian and military applications is also briefly addressed. Attention is also given to the roles civil society and research ethics may play in the governance of dual-use sciences and technologies. PMID:24497004

  15. Do p+p Collisions Flow at RHIC? Understanding One-Particle Distributions, Multiplicity Evolution, and Conservation Laws

    NASA Astrophysics Data System (ADS)

    Chajęcki, Zbigniew; Lisa, Mike

    2009-11-01

    Collective, explosive flow in central heavy ion collisions manifests itself in the mass dependence of p distributions and femtoscopic length scales, measured in the soft sector (p≲1GeV/c). Measured p distributions from proton-proton collisions differ significantly from those from heavy ion collisions. This has been taken as evidence that p+p collisions generate little collective flow, a conclusion in line with naive expectations. We point out possible hazards of ignoring phase-space restrictions due to conservation laws when comparing high- and low-multiplicity final states. Already in two-particle correlation functions, we see clear signals of such phase-space restrictions in low-multiplicity collisions at RHIC. We discuss how these same effects, then, must appear in the single particle spectra. We argue that the effects of energy and momentum conservation actually dominate the observed systematics, and that p+p collisions may be much more similar to heavy ion collisions than generally thought.

  16. Temporal Variation of Aerosol Properties at a Rural Continental Site and Study of Aerosol Evolution through Growth Law Analysis

    NASA Technical Reports Server (NTRS)

    Wang, Jian; Collins, Don; Covert, David; Elleman, Robert; Ferrare, Richard A.; Gasparini, Roberto; Jonsson, Haflidi; Ogren, John; Sheridan, Patrick; Tsay, Si-Chee

    2006-01-01

    Aerosol size distributions were measured by a Scanning Mobility Particle Sizer (SMPS) onboard the CIRPAS Twin Otter aircraft during 16 flights at the Southern Great Plains (SGP) site in northern central Oklahoma as part of the Aerosol Intensive Operation period in May, 2003. During the same period a second SMPS was deployed at a surface station and provided continuous measurements. Combined with trace gas measurements at the SGP site and back-trajectory analysis, the aerosol size distributions provided insights into the sources of aerosols observed at the SGP site. High particle concentrations, observed mostly during daytime, were well correlated with the sulfur dioxide (SO2) mixing ratios, suggesting nucleation involving sulfuric acid is likely the main source of newly formed particles at the SGP. Aerosols within plumes originating from wildfires in Central America were measured at the surface site. Vertically compact aerosol layers, which can be traced back to forest fires in East Asia, were intercepted at altitudes over 3000 meters. Analyses of size dependent particle growth rates for four periods during which high cloud coverage was observed indicate growth dominated by volume controlled reactions. Sulfate accounts for 50% to 72% of the increase in aerosol volume concentration; the rest of the volume concentration increase was likely due to secondary organic species. The growth law analyses and meteorological conditions indicate that the sulfate was produced mainly through aqueous oxidation of SO2 in clouds droplets and hydrated aerosol particles.

  17. Temporal variation of aerosol properties at a rural continental site and study of aerosol evolution through growth law analysis

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Collins, Don; Covert, David; Elleman, Robert; Ferrare, Richard A.; Gasparini, Roberto; Jonsson, Haflidi; Ogren, John; Sheridan, Patrick; Tsay, Si-Chee

    2006-09-01

    Aerosol size distributions were measured by a Scanning Mobility Particle Sizer (SMPS) on board the CIRPAS Twin Otter aircraft during 16 flights at the Southern Great Plains (SGP) site in northern central Oklahoma as part of the Aerosol Intensive Operation period in May 2003. During the same period a second SMPS was deployed at a surface station and provided continuous measurements. Combined with trace gas measurements at the SGP site and back trajectory analysis, the aerosol size distributions provided insights into the sources of aerosols observed at the SGP site. High particle concentrations, observed mostly during daytime, were well correlated with the sulfur dioxide (SO2) mixing ratios, suggesting nucleation involving sulfuric acid is likely the main source of newly formed particles at the SGP. Aerosols within plumes originating from wildfires in Central America were measured at the surface site. Vertically compact aerosol layers, which can be traced back to forest fires in East Asia, were intercepted at altitudes over 3000 m. Analyses of size-dependent particle growth rates for four periods during which high cloud coverage was observed indicate growth dominated by volume controlled reactions. Sulfate accounts for 50% to 72% of the increase in aerosol volume concentration; the rest of the volume concentration increase was likely due to secondary organic species. The growth law analyses and meteorological conditions indicate that the sulfate was produced mainly through aqueous oxidation of SO2 in clouds droplets and hydrated aerosol particles.

  18. Continuum damage model for ferroelectric materials and its application to multilayer actuators

    NASA Astrophysics Data System (ADS)

    Gellmann, Roman; Ricoeur, Andreas

    2016-05-01

    In this paper a micromechanical continuum damage model for ferroelectric materials is presented. As a constitutive law it is implemented into a finite element (FE) code. The model is based on micromechanical considerations of domain switching and its interaction with microcrack growth and coalescence. A FE analysis of a multilayer actuator is performed, showing the initiation of damage zones at the electrode tips during the poling process. Further, the influence of mechanical pre-stressing on damage evolution and actuating properties is investigated. The results provided in this work give useful information on the damage of advanced piezoelectric devices and their optimization.

  19. Preventing Persons Affected by Serious Mental Illnesses from Obtaining Firearms: The Evolution of Law, Policy, and Practice in Massachusetts.

    PubMed

    Silver, James; Fisher, William H; Silver, Emily

    2015-06-01

    A history of commitment to a mental health facility disqualifies applicants for gun licenses. Identifying such a history has become increasingly complex as the locus of confinement has become more diversified and privatized. In Massachusetts, prior to 2014, the databases used to identify individuals who would be disqualified on such grounds had not contemporaneously matched the evolution of the state's mental health systems. A survey of Massachusetts police chiefs, who, as in many jurisdictions, are charged with certifying qualification, indicates that some have broadened the scope of their background checks to include the experience of their officers with respect to certain applicants. The survey identifying these patterns, conducted in 2014, preceded by one month significant legislative reforms that mandate the modification of the reporting into a centralized database commitments to all types of mental health and substance use facilities, thus allowing identification of all commitments occurring in the state. The anticipated utilization of a different database mechanism, which has parallels in several other states, potentially streamlines the background check process, but raises numerous concerns that need to be addressed in developing and using such databases. PMID:25737302

  20. Mechanical Response of Stitched T300 Mat/Urethane 420 IMR Composite Laminates: Property/Orientation Dependence and Damage Evolution

    SciTech Connect

    Deng, S.; Weitsman, Y.J.

    2000-03-01

    This report presents experimental and analytical results of investigations on the mechanical response of stitched T300 mat/urethane 420 IMR composite laminates with three different lay-up configurations. Tensile tests and short-term creep and recovery tests were conducted on the laminate coupons at various orientations. The X-ray photographic technique was adopted to detect the internal damage due to external loading history. The tensile data of laminates with antisymmetric and symmetric lay-ups indicated that lay- up sequences of cross-ply laminates do not have much influence on their tensile properties. However, misalignments within the stitch-bonded plies disturb the symmetry of intended quasi-isotropic laminates and thereby cause the mechanical properties to exhibit a certain amount of angular dependence. Classic lamination theory was found to be able to provide a very good prediction of tensile properties for the stitched laminates within linear range. Creep and recovery response of laminate coupons is greatly dependent on loading angles and load levels. The internal damage of laminate coupons is also directly related to loading angles and load levels as well as loading history.

  1. Evolution equation of population genetics: Relation to the density-matrix theory of quasiparticles with general dispersion laws

    NASA Astrophysics Data System (ADS)

    Bezák, V.

    2003-02-01

    The Waxman-Peck theory of population genetics is discussed in regard of soil bacteria. Each bacterium is understood as a carrier of a phenotypic parameter p. The central objective is the calculation of the probability density with respect to p, Φ(p,t;p0), of the carriers living at time t>0, provided that initially at t0=0, all bacteria carried the phenotypic parameter p0=0. The theory involves two small parameters: the mutation probability μ and a parameter γ involved in a function w(p) defining the fitness of the bacteria to survive the generation time τ and give birth to an offspring. The mutation from a state p to a state q is defined by a Gaussian with a dispersion σ2m. The author focuses our attention on a function φ(p,t) which determines uniquely the function Φ(p,t;p0) and satisfies a linear equation (Waxman’s equation). The Green function of this equation is mathematically identical with the one-particle Bloch density matrix, where μ characterizes the order of magnitude of the potential energy. (In the x representation, the potential energy is proportional to the inverted Gaussian with the dispersion σ2m). The author solves Waxman’s equation in the standard style of a perturbation theory and discusses how the solution depends on the choice of the fitness function w(p). In a sense, the function c(p)=1-w(p)/w(0) is analogous to the dispersion function E(p) of fictitious quasiparticles. In contrast to Waxman’s approximation, where c(p) was taken as a quadratic function, c(p)≈γp2, the author exemplifies the problem with another function, c(p)=γ[1-exp(-ap2)], where γ is small but a may be large. The author shows that the use of this function in the theory of the population genetics is the same as the use of a nonparabolic dispersion law E=E(p) in the density-matrix theory. With a general function c(p), the distribution function Φ(p,t;0) is composed of a δ-function component, N(t)δ(p), and a blurred component. When discussing the limiting transition for t→∞, the author shows that his function c(p) implies that N(t)→N(∞)≠0 in contrast with the asymptotics N(t)→0 resulting from the use of Waxman’s function c(p)˜p2.

  2. Modeling Fatigue Damage in Long-Fiber Thermoplastics

    SciTech Connect

    Nguyen, Ba Nghiep; Kunc, Vlastimil; Bapanapalli, Satish K.

    2009-10-30

    This paper applies a fatigue damage model recently developed for injection-molded long-fiber thermoplastics (LFTs) to predict the modulus reduction and fatigue lifetime of glass/polyamide 6,6 (PA6,6) specimens. The fatigue model uses a multiscale mechanistic approach to describe fatigue damage accumulation in these materials subjected to cyclic loading. Micromechanical modeling using a modified Eshelby-Mori-Tanaka approach combined with averaging techniques for fiber length and orientation distributions is performed to establish the stiffness reduction relation for the composite as a function of the microcrack volume fraction. Next, continuum damage mechanics and a thermodynamic formulation are used to derive the constitutive relations and the damage evolution law. The fatigue damage model has been implemented in the ABAQUS finite element code and has been applied to analyze fatigue of the studied glass/PA6,6 specimens. The predictions agree well with the experimental results.

  3. A model for time-independent and time-dependent damage evolution and their influence on creep of multidirectional polymer composite laminates

    NASA Astrophysics Data System (ADS)

    Asadi, Amir

    Application of polymer matrix composites in engineering structures has been steadily increasing over the past five decades. Multidirectional polymer composites are one class of continuous fiber reinforced polymer matrix composites used in aerospace structures, where the desired mechanical performance outweighs the cost. Their modulus and strength degrade with time (known as creep and creep rupture) during the service, owing to the viscos-elasticity of the polymer matrix. Additional contribution to this degradation comes from various damage modes developed in the plies of the composite with time and identified in this thesis as TDD (Time Dependent Damage). These damage modes may also develop due to process-induced residual stresses, and during loading to the service load, identified as TID (Time Independent Damage). TID influences the TDD, the creep and the creep rupture. The objective of this thesis is to develop a model to predict the evolution of TID and TDD in multiple plies of a laminate and their influence on creep. The predominant damage mode, transverse cracking, is modeled in this study. The model consists of four modules, PIS, QSL, SL, and VA. The PIS, QSL, and SL moduli predict changes in ply stresses for incremental change in temperature, stress, and time respectively, using lamination theory and assuming linear elastic behavior of the plies during an incremental step. In parallel, each module predicts the stored elastic energy in each ply after each incremental step and compares it with a critical stored elastic energy criterion to determine if a ply would crack. If fracture is predicted, the VA module based on variational analysis, is invoked to determine the crack density and the perturbation in ply stresses due to cracking. The perturbation stresses are used by the module that invoked the VA module to determine the ply stresses after cracking during the current incremental step. The model predictions for a [+/-45/90]s laminate, at two test temperatures (80°C and 180°C) and four stresses in the range of 20--54 MPa, compare very well with experimental results validating the model.

  4. A SMALL-SCALE DAMAGE APPROACH TO PREDICT FATIGUE CRACK GROWTH IN CERAMIC MATERIALS

    SciTech Connect

    Nguyen, Ba Nghiep; Koeppel, Brian J.; Khaleel, Mohammad A.

    2006-05-19

    This paper proposes a small-scale damage modeling approach to predict fatigue crack growth in ceramic materials. A fatigue damage model is formulated that uses two variables. One variable is the scalar damage variable governing the reduction of stiffness, and the other is the number of cycles. The damage evolution law is obtained based on thermodynamics of continuous media and a damage criterion containing a damage threshold function that depends on the damage variable and the cyclic loading parameters. The model has been implemented into the ABAQUS finite element code via user-subroutines and has been used in a modified boundary layer (MBL) modeling approach to analyze fatigue crack growth in a small fracture process zone situated at an initial crack tip. The model application is illustrated through an analysis of fatigue crack growth in an yttria-stabilized tetragonal zirconia material.

  5. Damage evolution of bi-body model composed of weakly cemented soft rock and coal considering different interface effect.

    PubMed

    Zhao, Zenghui; Lv, Xianzhou; Wang, Weiming; Tan, Yunliang

    2016-01-01

    Considering the structure effect of tunnel stability in western mining of China, three typical kinds of numerical model were respectively built as follows based on the strain softening constitutive model and linear elastic-perfectly plastic model for soft rock and interface: R-M, R-C(s)-M and R-C(w)-M. Calculation results revealed that the stress-strain relation and failure characteristics of the three models vary between each other. The combination model without interface or with a strong interface presented continuous failure, while weak interface exhibited 'cut off' effect. Thus, conceptual models of bi-material model and bi-body model were established. Then numerical experiments of tri-axial compression were carried out for the two models. The relationships between stress evolution, failure zone and deformation rate fluctuations as well as the displacement of interface were detailed analyzed. Results show that two breakaway points of deformation rate actually demonstrate the starting and penetration of the main rupture, respectively. It is distinguishable due to the large fluctuation. The bi-material model shows general continuous failure while bi-body model shows 'V' type shear zone in weak body and failure in strong body near the interface due to the interface effect. With the increasing of confining pressure, the 'cut off' effect of weak interface is not obvious. These conclusions lay the theoretical foundation for further development of constitutive model for soft rock-coal combination body. PMID:27066329

  6. Water, law, science

    NASA Astrophysics Data System (ADS)

    Narasimhan, T. N.

    2008-01-01

    SummaryIn a world with water resources severely impacted by technology, science must actively contribute to water law. To this end, this paper is an earth scientist's attempt to comprehend essential elements of water law, and to examine their connections to science. Science and law share a common logical framework of starting with a priori prescribed tenets, and drawing consistent inferences. In science, observationally established physical laws constitute the tenets, while in law, they stem from social values. The foundations of modern water law in Europe and the New World were formulated nearly two thousand years ago by Roman jurists who were inspired by Greek philosophy of reason. Recognizing that vital natural elements such as water, air, and the sea were governed by immutable natural laws, they reasoned that these elements belonged to all humans, and therefore cannot be owned as private property. Legally, such public property was to be governed by jus gentium, the law of all people or the law of all nations. In contrast, jus civile or civil law governed private property. Remarkably, jus gentium continues to be relevant in our contemporary society in which science plays a pivotal role in exploiting vital resources common to all. This paper examines the historical roots of modern water law, follows their evolution through the centuries, and examines how the spirit of science inherent in jus gentium is profoundly influencing evolving water and environmental laws in Europe, the United States and elsewhere. In a technological world, scientific knowledge has to lie at the core of water law. Yet, science cannot formulate law. It is hoped that a philosophical understanding of the relationships between science and law will contribute to their constructively coming together in the service of society.

  7. International law and law enforcement firearms.

    PubMed

    Jussila, Jorma; Normia, Pertti

    2004-01-01

    Several international agreements set constraints on the legitimate use of firearms as representing lethal force. Their meaning in terms of weapons technology must take into account their operational frame of reference, and legitimate warfare can be regarded as a law enforcement operation with similar principles on the use of force. Changes in weapons technology, such as new types of ammunition, transforming firearms into weapons with less-lethal and even humanitarian options, require new interpretations of the legislation. A division into lethal and non-lethal weapons is an oversimplification and the separation of international humanitarian law into military and law enforcement provisions can be questioned from the technical aspect. The type of technology acceptable for law enforcement use of firearms should be defined. An assessment for weapon injury should not be based on lethality, but rather on the potential for tissue damage and its reversibility. PMID:15015547

  8. 32 CFR 537.5 - Applicable law.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    .... However, as to what law of damages is applicable, Maryland or Virginia depecage (choice of law) theory may... years, or the insurer's notice requirement set forth in the policy. United States v. Hartford...

  9. 32 CFR 537.5 - Applicable law.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    .... However, as to what law of damages is applicable, Maryland or Virginia depecage (choice of law) theory may... years, or the insurer's notice requirement set forth in the policy. United States v. Hartford...

  10. 32 CFR 537.5 - Applicable law.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    .... However, as to what law of damages is applicable, Maryland or Virginia depecage (choice of law) theory may... years, or the insurer's notice requirement set forth in the policy. United States v. Hartford...

  11. Computer simulation of creep damage at crack tip in short fibre composites

    NASA Astrophysics Data System (ADS)

    Shuangyin, Zhang; Tsai, L. W.

    1994-08-01

    Creep damage at crack tip in short fibre composites has been simulated by using the finite element method (FEM). The well-known Schapery non-linear viscoelastic constitutive relationship was used to characterize time-dependent behaviour of the material. A modified recurrence equation was adopted to accelerate the iteration. Kachanov-Rabotnov's damage evolution law was employed. The growth of the damage zone with time around the crack tip was calculated and the results were shown with the so-called “digit photo”, which was produced by the printer.

  12. 43 CFR 8365.1-7 - State and local laws.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... and local laws. Except as otherwise provided by Federal law or regulation, State and local laws and..., or destruction or damage to property; (e) Air and water pollution; (f) Littering; (g) Sanitation;...

  13. 43 CFR 8365.1-7 - State and local laws.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... and local laws. Except as otherwise provided by Federal law or regulation, State and local laws and..., or destruction or damage to property; (e) Air and water pollution; (f) Littering; (g) Sanitation;...

  14. 43 CFR 8365.1-7 - State and local laws.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... and local laws. Except as otherwise provided by Federal law or regulation, State and local laws and..., or destruction or damage to property; (e) Air and water pollution; (f) Littering; (g) Sanitation;...

  15. Water, law, science

    SciTech Connect

    Narasimhan, T.N.

    2007-10-17

    In a world with water resources severely impacted bytechnology, science must actively contribute to water law. To this end,this paper is an earth scientist s attempt to comprehend essentialelements of water law, and to examine their connections to science.Science and law share a common logical framework of starting with apriori prescribed tenets, and drawing consistent inferences. In science,observationally established physical laws constitute the tenets, while inlaw, they stem from social values. The foundations of modern water law inEurope and the New World were formulated nearly two thousand years ago byRoman jurists who were inspired by Greek philosophy of reason.Recognizing that vital natural elements such as water, air, and the seawere governed by immutable natural laws, they reasoned that theseelements belonged to all humans, and therefore cannot be owned as privateproperty. Legally, such public property was to be governed by jusgentium, the law of all people or the law of all nations. In contrast,jus civile or civil law governed private property. Remarkably, jusgentium continues to be relevant in our contemporary society in whichscience plays a pivotal role in exploiting vital resources common to all.This paper examines the historical roots of modern water law, followstheir evolution through the centuries, and examines how the spirit ofscience inherent in jus gentium is profoundly influencing evolving waterand environmental laws in Europe, the United States and elsewhere. In atechnological world, scientific knowledge has to lie at the core of waterlaw. Yet, science cannot formulate law. It is hoped that a philosophicalunderstanding of the relationships between science and law willcontribute to their constructively coming together in the service ofsociety.

  16. Prediction Of Formability In Sheet Metal Forming Processes Using A Local Damage Model

    SciTech Connect

    Teixeira, P.; Santos, Abel; Cesar Sa, J.; Andrade Pires, F.; Barata da Rocha, A.

    2007-05-17

    The formability in sheet metal forming processes is mainly conditioned by ductile fracture resulting from geometric instabilities due to necking and strain localization. The macroscopic collapse associated with ductile failure is a result of internal degradation described throughout metallographic observations by the nucleation, growth and coalescence of voids and micro-cracks. Damage influences and is influenced by plastic deformation and therefore these two dissipative phenomena should be coupled at the constitutive level. In this contribution, Lemaitre's ductile damage model is coupled with Hill's orthotropic plasticity criterion. The coupling between damaging and material behavior is accounted for within the framework of Continuum Damage Mechanics (CDM). The resulting constitutive equations are implemented in the Abaqus/Explicit code, for the prediction of fracture onset in sheet metal forming processes. The damage evolution law takes into account the important effect of micro-crack closure, which dramatically decreases the rate of damage growth under compressive paths.

  17. Medium energy ion scattering analysis of the evolution and annealing of damage and associated dopant redistribution of ultra shallow implants in Si

    NASA Astrophysics Data System (ADS)

    van den Berg, J. A.; Reading, M. A.; Armour, D. G.; Carter, G.; Zalm, P. C.; Bailey, P.; Noakes, T. C. Q.

    As junction depths in advanced semiconductor devices move to below 20 nm, the process of disorder evolution during ion implantation at ultra low energies becomes increasingly influenced by the surface. This may also hold for shallow regrowth and dopant redistribution processes during subsequent thermal annealing of the substrate. The investigation of these near-surface processes requires analytical techniques with a depth resolution of≤1 nm. Medium energy ion scattering (MEIS) has the unique capability of simultaneously providing quantitative, high-resolution depth distributions of implant disorder (displaced Si lattice atoms) and of implanted atoms, albeit not of light species. We report here a comparative MEIS investigation into the growth mode of shallow disordered/amorphised layers during≤1 keV B+ and 2.5 keV As+ ion implantation into Si. In both cases the growth of the damage depth profiles differs significantly from the energy deposition function, as it is strongly determined on the one hand by the proximity of the surface acting as a nucleation site for migrating point defects formed during implantation, which results in planar growth of the amorphous layer, and on the other by the dynamic annealing processes operating at room temperature. When such defect recombination processes are inhibited, e.g. for low dose, ultra shallow 200 eV B+ implants, MEIS shows that defect production yields exceeding the Kinchin-Pease model predictions are achieved. For As implants, a correlation is observed between the movement of the As and the depth of the growing, planar amorphous layer. Thermal annealing of As implanted samples at different temperatures and durations leads to solid phase epitaxial regrowth. During regrowth, MEIS shows that there is a close correlation between damage dissolution, the movement of nearly half of the As dopant into substitutional sites and the snowploughing of a fraction of the As in front of the advancing amorphous/crystalline interface leading to the formation of a less than 1 nm wide As pile-up layer trapped under the oxide.

  18. Cumulative creep damage for polycarbonate and polysulfone

    NASA Technical Reports Server (NTRS)

    Zhang, M.; Brinson, H. F.

    1985-01-01

    The literature for creep to failure cumulative damage laws are reviewed. Creep to failure tests performed on polycarbonate and polysulfone under single and two step loadings are discussed. A cumulative damage law or modified time fraction rule is developed using a power law for transient creep response as the starting point. Experimental results are approximated well by the new rule. Damage and failure mechanisms associated with the two materials are suggested.

  19. 32 CFR 750.33 - Damages.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 5 2013-07-01 2013-07-01 false Damages. 750.33 Section 750.33 National Defense... Claims Act § 750.33 Damages. (a) Generally. The measure of damages is determined by the law of the place... for interest prior to judgment or for punitive damages. In a death case, if the place where the act...

  20. 32 CFR 750.33 - Damages.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 5 2011-07-01 2011-07-01 false Damages. 750.33 Section 750.33 National Defense... Claims Act § 750.33 Damages. (a) Generally. The measure of damages is determined by the law of the place... for interest prior to judgment or for punitive damages. In a death case, if the place where the act...

  1. 32 CFR 750.33 - Damages.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 5 2012-07-01 2012-07-01 false Damages. 750.33 Section 750.33 National Defense... Claims Act § 750.33 Damages. (a) Generally. The measure of damages is determined by the law of the place... for interest prior to judgment or for punitive damages. In a death case, if the place where the act...

  2. 32 CFR 750.33 - Damages.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 5 2014-07-01 2014-07-01 false Damages. 750.33 Section 750.33 National Defense... Claims Act § 750.33 Damages. (a) Generally. The measure of damages is determined by the law of the place... for interest prior to judgment or for punitive damages. In a death case, if the place where the act...

  3. 32 CFR 750.33 - Damages.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 5 2010-07-01 2010-07-01 false Damages. 750.33 Section 750.33 National Defense... Claims Act § 750.33 Damages. (a) Generally. The measure of damages is determined by the law of the place... for interest prior to judgment or for punitive damages. In a death case, if the place where the act...

  4. Heat transfer in damaged material

    NASA Astrophysics Data System (ADS)

    Kruis, J.

    2013-10-01

    Fully coupled thermo-mechanical analysis of civil engineering problems is studied. The mechanical analysis is based on damage mechanics which is useful for modeling of behaviour of quasi-brittle materials, especially in tension. The damage is assumed to be isotropic. The heat transfer is assumed in the form of heat conduction governed by the Fourier law and heat radiation governed by the Stefan-Boltzmann law. Fully coupled thermo-mechanical problem is formulated.

  5. Limit laws for Zipf's law

    NASA Astrophysics Data System (ADS)

    Eliazar, Iddo

    2011-01-01

    In this communication we establish stochastic limit laws leading from Zipf's law to Pareto's and Heaps' laws. We consider finite ensembles governed by Zipf's law and study their asymptotic statistics as the ensemble size tends to infinity. A Lorenz-curve analysis establishes three types of limit laws for the ensembles' statistical structure: 'communist', 'monarchic', and Paretian. Further considering a dynamic setting in which the ensembles grow stochastically in time, a functional central limit theorem analysis establishes a Gaussian approximation for the ensembles' stochastic growth. The Gaussian approximation provides a generalized and corrected formulation of Heaps' law.

  6. Courtside: A Damaging Lesson

    ERIC Educational Resources Information Center

    Zirkel, Perry A.

    2004-01-01

    This case presents a costly lesson for teachers and for districts that include a liquidated, or stipulated, damages clause in their teacher employment contracts. Although the court enforced the clause in this case, in this well-reasoned recent decision and in most of the much older, canvassed case law from other jurisdictions, the answer to the…

  7. MULTI-WAVELENGTH OBSERVATIONS OF THE SPATIO-TEMPORAL EVOLUTION OF SOLAR FLARES WITH AIA/SDO. II. HYDRODYNAMIC SCALING LAWS AND THERMAL ENERGIES

    SciTech Connect

    Aschwanden, Markus J.; Shimizu, Toshifumi E-mail: shimizu.toshifumi@isas.jaxa.jp

    2013-10-20

    In this study we measure physical parameters of the same set of 155 M- and X-class solar flares observed with AIA/SDO as analyzed in Paper I, by performing a differential emission measure analysis to determine the flare peak emission measure EM{sub p} , peak temperature T{sub p} , electron density n{sub p} , and thermal energy E{sub th}, in addition to the spatial scales L, areas A, and volumes V measured in Paper I. The parameter ranges for M- and X-class flares are log (EM{sub p}) = 47.0-50.5, T{sub p} = 5.0-17.8 MK, n{sub p} = 4 × 10{sup 9}-9 × 10{sup 11} cm{sup –3}, and thermal energies of E{sub th} = 1.6 × 10{sup 28}-1.1 × 10{sup 32} erg. We find that these parameters obey the Rosner-Tucker-Vaiana (RTV) scaling law T{sub p}{sup 2}∝n{sub p} L and H∝T {sup 7/2} L {sup –2} during the peak time t{sub p} of the flare density n{sub p} , when energy balance between the heating rate H and the conductive and radiative loss rates is achieved for a short instant and thus enables the applicability of the RTV scaling law. The application of the RTV scaling law predicts power-law distributions for all physical parameters, which we demonstrate with numerical Monte Carlo simulations as well as with analytical calculations. A consequence of the RTV law is also that we can retrieve the size distribution of heating rates, for which we find N(H)∝H {sup –1.8}, which is consistent with the magnetic flux distribution N(Φ)∝Φ{sup –1.85} observed by Parnell et al. and the heating flux scaling law F{sub H} ∝HL∝B/L of Schrijver et al.. The fractal-diffusive self-organized criticality model in conjunction with the RTV scaling law reproduces the observed power-law distributions and their slopes for all geometrical and physical parameters and can be used to predict the size distributions for other flare data sets, instruments, and detection algorithms.

  8. Micro-Macro Analysis and Phenomenological Modelling of Salt Viscous Damage and Application to Salt Caverns

    NASA Astrophysics Data System (ADS)

    Zhu, Cheng; Pouya, Ahmad; Arson, Chloé

    2015-11-01

    This paper aims to gain fundamental understanding of the microscopic mechanisms that control the transition between secondary and tertiary creep around salt caverns in typical geological storage conditions. We use a self-consistent inclusion-matrix model to homogenize the viscoplastic deformation of halite polycrystals and predict the number of broken grains in a Representative Elementary Volume of salt. We use this micro-macro modeling framework to simulate creep tests under various axial stresses, which gives us the critical viscoplastic strain at which grain breakage (i.e., tertiary creep) is expected to occur. The comparison of simulation results for short-term and long-term creep indicates that the initiation of tertiary creep depends on the stress and the viscoplastic strain. We use the critical viscoplastic deformation as a yield criterion to control the transition between secondary and tertiary creep in a phenomenological viscoplastic model, which we implement into the Finite Element Method program POROFIS. We model a 850-m-deep salt cavern of irregular shape, in axis-symmetric conditions. Simulations of cavern depressurization indicate that a strain-dependent damage evolution law is more suitable than a stress-dependent damage evolution law, because it avoids high damage concentrations and allows capturing the formation of a damaged zone around the cavity. The modeling framework explained in this paper is expected to provide new insights to link grain breakage to phenomenological damage variables used in Continuum Damage Mechanics.

  9. An anisotropic thermomechanical damage model for concrete at transient elevated temperatures.

    PubMed

    Baker, Graham; de Borst, René

    2005-11-15

    The behaviour of concrete at elevated temperatures is important for an assessment of integrity (strength and durability) of structures exposed to a high-temperature environment, in applications such as fire exposure, smelting plants and nuclear installations. In modelling terms, a coupled thermomechanical analysis represents a generalization of the computational mechanics of fracture and damage. Here, we develop a fully coupled anisotropic thermomechanical damage model for concrete under high stress and transient temperature, with emphasis on the adherence of the model to the laws of thermodynamics. Specific analytical results are given, deduced from thermodynamics, of a novel interpretation on specific heat, evolution of entropy and the identification of the complete anisotropic, thermomechanical damage surface. The model is also shown to be stable in a computational sense, and to satisfy the laws of thermodynamics. PMID:16243703

  10. Cumulative creep damage for polycarbonate and polysulfone

    NASA Technical Reports Server (NTRS)

    Zhang, M. J.; Straight, M. R.; Brinson, H. F.

    1985-01-01

    Creep to failure tests performed on polycarbonate and polysulfone under single and two step loadings are discussed. A cumulative damage law or modified time fraction rule is developed using a power law for transient creep response as the starting point. Experimental results are approximated well by the new rule. Damage and failure mechanisms associated with the two materials are suggested.

  11. Exact law of live nature

    NASA Astrophysics Data System (ADS)

    Azbel, Mark Ya.

    2005-07-01

    Exact law of mortality dynamics in changing populations and environment is derived. It includes no explicit characteristics of animal- environment interactions (metabolism etc) which are a must for life; it is universal for all animals, from single cell yeast to humans, with their drastically different biology, evolutionary history, and complexity; it is rapidly (within few percent of life span) reversible. Such law is unique for live systems with their homeostatic self-adjustment to environment (cf. thermodynamics of liquids and glasses). The law which is valid for all live, and only live, systems is their specific natural law. Mortality is an instrument of natural selection and biological diversity. Its law, which is preserved in evolution of all species, is a conservation law of mortality, selection, evolution, biology. The law implies new kind of intrinsic mortality and adaptation which dominate in evolutionary unprecedented protected populations and, in contrast to species specific natural selection, proceed via universal stepwise rungs and reduce to universal cellular mechanism. The law demonstrates that intrinsic mortality and at least certain aspects of aging are disposable evolutionary byproducts, and directed genetic and/or biological changes may yield healthy and vital Methuselah lifespan. This is consistent with experiments. Universality implies that single cell yeast may provide a master key to the cellular mechanism of universal mortality, aging, selection, evolution, and its regulation in all animals. One may look for its manifestations in animal cells also, e.g., in their replicative senescence and cancer. Evolutionary origin and genetic nature of universality are suggested.

  12. A model for high temperature creep of single crystal superalloys based on nonlocal damage and viscoplastic material behavior

    NASA Astrophysics Data System (ADS)

    Trinh, B. T.; Hackl, K.

    2014-07-01

    A model for high temperature creep of single crystal superalloys is developed, which includes constitutive laws for nonlocal damage and viscoplasticity. It is based on a variational formulation, employing potentials for free energy, and dissipation originating from plasticity and damage. Evolution equations for plastic strain and damage variables are derived from the well-established minimum principle for the dissipation potential. The model is capable of describing the different stages of creep in a unified way. Plastic deformation in superalloys incorporates the evolution of dislocation densities of the different phases present. It results in a time dependence of the creep rate in primary and secondary creep. Tertiary creep is taken into account by introducing local and nonlocal damage. Herein, the nonlocal one is included in order to model strain localization as well as to remove mesh dependence of finite element calculations. Numerical results and comparisons with experimental data of the single crystal superalloy LEK94 are shown.

  13. Partition coefficients for REE between garnets and liquids - Implications of non-Henry's Law behaviour for models of basalt origin and evolution

    NASA Technical Reports Server (NTRS)

    Harrison, W. J.

    1981-01-01

    An experimental investigation of Ce, Sm and Tm rare earth element (REE) partition coefficients between coexisting garnets (both natural and synthetic) and hydrous liquids shows that Henry's Law may not be obeyed over a range of REE concentrations of geological relevance. Systematic differences between the three REE and the two garnet compositions may be explained in terms of the differences between REE ionic radii and those of the dodecahedral site into which they substitute, substantiating the Harrison and Wood (1980) model of altervalent substitution. Model calculations demonstrate that significant variation can occur in the rare earth contents of melts produced from a garnet lherzolite, if Henry's Law partition coefficients do not apply for the garnet phase.

  14. Limits of imagination: the 150th Anniversary of Mendel's Laws, and why Mendel failed to see the importance of his discovery for Darwin's theory of evolution.

    PubMed

    Singh, Rama S

    2015-09-01

    Mendel is credited for discovering Laws of Heredity, but his work has come under criticism on three grounds: for possible falsification of data to fit his expectations, for getting undue credit for the laws of heredity without having ideas of segregation and independent assortment, and for being interested in the development of hybrids rather than in the laws of heredity. I present a brief review of these criticisms and conclude that Mendel deserved to be called the father of genetics even if he may not, and most likely did not, have clear ideas of segregation and particulate determiners as we know them now. I argue that neither Mendel understood the evolutionary significance of his findings for the problem of genetic variation, nor would Darwin have understood their significance had he read Mendel's paper. I argue that the limits to imagination, in both cases, came from their mental framework being shaped by existing paradigms-blending inheritance in the case of Darwin, hybrid development in the case of Mendel. Like Einstein, Darwin's natural selection was deterministic; like Niels Bohr, Mendel's Laws were probabilistic-based on random segregation of trait-determining "factors". Unlike Einstein who understood quantum mechanics, Darwin would have been at a loss with Mendel's paper with no guide to turn to. Geniuses in their imaginations are like heat-seeking missiles locked-in with their targets of deep interests and they generally see things in one dimension only. Imagination has limits; unaided imagination is like a bird without wings--it goes nowhere. PMID:26372894

  15. Law 302.

    ERIC Educational Resources Information Center

    Manitoba Dept. of Education, Winnipeg.

    This publication outlines a law course intended as part of a business education program in the secondary schools of Manitoba, Canada. The one credit course of study should be taught over a period of 110-120 hours of instruction. It provides students with an introduction to the principles, practices, and consequences of law with regard to torts,…

  16. Interacting damage models mapped onto ising and percolation models

    SciTech Connect

    Toussaint, Renaud; Pride, Steven R.

    2004-03-23

    The authors introduce a class of damage models on regular lattices with isotropic interactions between the broken cells of the lattice. Quasistatic fiber bundles are an example. The interactions are assumed to be weak, in the sense that the stress perturbation from a broken cell is much smaller than the mean stress in the system. The system starts intact with a surface-energy threshold required to break any cell sampled from an uncorrelated quenched-disorder distribution. The evolution of this heterogeneous system is ruled by Griffith's principle which states that a cell breaks when the release in potential (elastic) energy in the system exceeds the surface-energy barrier necessary to break the cell. By direct integration over all possible realizations of the quenched disorder, they obtain the probability distribution of each damage configuration at any level of the imposed external deformation. They demonstrate an isomorphism between the distributions so obtained and standard generalized Ising models, in which the coupling constants and effective temperature in the Ising model are functions of the nature of the quenched-disorder distribution and the extent of accumulated damage. In particular, they show that damage models with global load sharing are isomorphic to standard percolation theory, that damage models with local load sharing rule are isomorphic to the standard ising model, and draw consequences thereof for the universality class and behavior of the autocorrelation length of the breakdown transitions corresponding to these models. they also treat damage models having more general power-law interactions, and classify the breakdown process as a function of the power-law interaction exponent. Last, they also show that the probability distribution over configurations is a maximum of Shannon's entropy under some specific constraints related to the energetic balance of the fracture process, which firmly relates this type of quenched-disorder based damage model to standard statistical mechanics.

  17. Irreversible entropy model for damage diagnosis in resistors

    NASA Astrophysics Data System (ADS)

    Cuadras, Angel; Crisóstomo, Javier; Ovejas, Victoria J.; Quilez, Marcos

    2015-10-01

    We propose a method to characterize electrical resistor damage based on entropy measurements. Irreversible entropy and the rate at which it is generated are more convenient parameters than resistance for describing damage because they are essentially positive in virtue of the second law of thermodynamics, whereas resistance may increase or decrease depending on the degradation mechanism. Commercial resistors were tested in order to characterize the damage induced by power surges. Resistors were biased with constant and pulsed voltage signals, leading to power dissipation in the range of 4-8 W, which is well above the 0.25 W nominal power to initiate failure. Entropy was inferred from the added power and temperature evolution. A model is proposed to understand the relationship among resistance, entropy, and damage. The power surge dissipates into heat (Joule effect) and damages the resistor. The results show a correlation between entropy generation rate and resistor failure. We conclude that damage can be conveniently assessed from irreversible entropy generation. Our results for resistors can be easily extrapolated to other systems or machines that can be modeled based on their resistance.

  18. 3D Progressive Damage Modeling for Laminated Composite Based on Crack Band Theory and Continuum Damage Mechanics

    NASA Technical Reports Server (NTRS)

    Wang, John T.; Pineda, Evan J.; Ranatunga, Vipul; Smeltzer, Stanley S.

    2015-01-01

    A simple continuum damage mechanics (CDM) based 3D progressive damage analysis (PDA) tool for laminated composites was developed and implemented as a user defined material subroutine to link with a commercially available explicit finite element code. This PDA tool uses linear lamina properties from standard tests, predicts damage initiation with an easy-to-implement Hashin-Rotem failure criteria, and in the damage evolution phase, evaluates the degradation of material properties based on the crack band theory and traction-separation cohesive laws. It follows Matzenmiller et al.'s formulation to incorporate the degrading material properties into the damaged stiffness matrix. Since nonlinear shear and matrix stress-strain relations are not implemented, correction factors are used for slowing the reduction of the damaged shear stiffness terms to reflect the effect of these nonlinearities on the laminate strength predictions. This CDM based PDA tool is implemented as a user defined material (VUMAT) to link with the Abaqus/Explicit code. Strength predictions obtained, using this VUMAT, are correlated with test data for a set of notched specimens under tension and compression loads.

  19. A damage mechanics based general purpose interface/contact element

    NASA Astrophysics Data System (ADS)

    Yan, Chengyong

    Most of the microelectronics packaging structures consist of layered substrates connected with bonding materials, such as solder or epoxy. Predicting the thermomechanical behavior of these multilayered structures is a challenging task in electronic packaging engineering. In a layered structure the most complex part is always the interfaces between the strates. Simulating the thermo-mechanical behavior of such interfaces, is the main theme of this dissertation. The most commonly used solder material, Pb-Sn alloy, has a very low melting temperature 180sp°C, so that the material demonstrates a highly viscous behavior. And, creep usually dominates the failure mechanism. Hence, the theory of viscoplasticity is adapted to describe the constitutive behavior. In a multilayered assembly each layer has a different coefficient of thermal expansion. Under thermal cycling, due to heat dissipated from circuits, interfaces and interconnects experience low cycle fatigue. Presently, the state-of-the art damage mechanics model used for fatigue life predictions is based on Kachanov (1986) continuum damage model. This model uses plastic strain as a damage criterion. Since plastic strain is a stress path dependent value, the criterion does not yield unique damage values for the same state of stress. In this dissertation a new damage evolution equation based on the second law of thermodynamic is proposed. The new criterion is based on the entropy of the system and it yields unique damage values for all stress paths to the final state of stress. In the electronics industry, there is a strong desire to develop fatigue free interconnections. The proposed interface/contact element can also simulate the behavior of the fatigue free Z-direction thin film interconnections as well as traditional layered interconnects. The proposed interface element can simulate behavior of a bonded interface or unbonded sliding interface, also called contact element. The proposed element was verified against laboratory test data presented in the literature. The results demonstrate that the proposed element and the damage law perform very well. The most important scientific contribution of this dissertation is the proposed damage criterion based on second law of thermodynamic and entropy of the system. The proposed general purpose interface/contact element is another contribution of this research. Compared to the previous adhoc interface elements proposed in the literature, the new one is, much more powerful and includes creep, plastic deformations, sliding, temperature, damage, cyclic behavior and fatigue life in a unified formulation.

  20. Progressive Damage Analysis of Laminated Composite (PDALC)-A Computational Model Implemented in the NASA COMET Finite Element Code

    NASA Technical Reports Server (NTRS)

    Lo, David C.; Coats, Timothy W.; Harris, Charles E.; Allen, David H.

    1996-01-01

    A method for analysis of progressive failure in the Computational Structural Mechanics Testbed is presented in this report. The relationship employed in this analysis describes the matrix crack damage and fiber fracture via kinematics-based volume-averaged variables. Damage accumulation during monotonic and cyclic loads is predicted by damage evolution laws for tensile load conditions. The implementation of this damage model required the development of two testbed processors. While this report concentrates on the theory and usage of these processors, a complete list of all testbed processors and inputs that are required for this analysis are included. Sample calculations for laminates subjected to monotonic and cyclic loads were performed to illustrate the damage accumulation, stress redistribution, and changes to the global response that occur during the load history. Residual strength predictions made with this information compared favorably with experimental measurements.

  1. Sun Damage

    MedlinePlus

    ... and rashes clinical tools newsletter | contact Share | Sun Damage A A A The sun has a profound ... rough or scaly areas of skin due to damage from sun exposure. Some actinic keratoses can turn ...

  2. MULTI-WAVELENGTH OBSERVATIONS OF THE SPATIO-TEMPORAL EVOLUTION OF SOLAR FLARES WITH AIA/SDO. I. UNIVERSAL SCALING LAWS OF SPACE AND TIME PARAMETERS

    SciTech Connect

    Aschwanden, Markus J.; Zhang, Jie; Liu, Kai E-mail: jzhang7@gmu.edu

    2013-09-20

    We extend a previous statistical solar flare study of 155 GOES M- and X-class flares observed with AIA/SDO to all seven coronal wavelengths (94, 131, 171, 193, 211, 304, and 335 Å) to test the wavelength dependence of scaling laws and statistical distributions. Except for the 171 and 193 Å wavelengths, which are affected by EUV dimming caused by coronal mass ejections (CMEs), we find near-identical size distributions of geometric (lengths L, flare areas A, volumes V, and fractal dimension D{sub 2}), temporal (flare durations T), and spatio-temporal parameters (diffusion coefficient κ, spreading exponent β, and maximum expansion velocities v{sub max}) in different wavelengths, which are consistent with the universal predictions of the fractal-diffusive avalanche model of a slowly driven, self-organized criticality (FD-SOC) system, i.e., N(L)∝L {sup –3}, N(A)∝A {sup –2}, N(V)∝V {sup –5/3}, N(T)∝T {sup –2}, and D{sub 2} = 3/2, for a Euclidean dimension d = 3. Empirically, we find also a new strong correlation κ∝L {sup 0.94±0.01} and the three-parameter scaling law L∝κ T {sup 0.1}, which is more consistent with the logistic-growth model than with classical diffusion. The findings suggest long-range correlation lengths in the FD-SOC system that operate in the vicinity of a critical state, which could be used for predictions of individual extreme events. We find also that eruptive flares (with accompanying CMEs) have larger volumes V, longer flare durations T, higher EUV and soft X-ray fluxes, and somewhat larger diffusion coefficients κ than confined flares (without CMEs)

  3. Progressive Damage Analysis of Laminated Composite (PDALC) (A Computational Model Implemented in the NASA COMET Finite Element Code). 2.0

    NASA Technical Reports Server (NTRS)

    Coats, Timothy W.; Harris, Charles E.; Lo, David C.; Allen, David H.

    1998-01-01

    A method for analysis of progressive failure in the Computational Structural Mechanics Testbed is presented in this report. The relationship employed in this analysis describes the matrix crack damage and fiber fracture via kinematics-based volume-averaged damage variables. Damage accumulation during monotonic and cyclic loads is predicted by damage evolution laws for tensile load conditions. The implementation of this damage model required the development of two testbed processors. While this report concentrates on the theory and usage of these processors, a complete listing of all testbed processors and inputs that are required for this analysis are included. Sample calculations for laminates subjected to monotonic and cyclic loads were performed to illustrate the damage accumulation, stress redistribution, and changes to the global response that occurs during the loading history. Residual strength predictions made with this information compared favorably with experimental measurements.

  4. Effects of multiaxial stress state and saltwater on fatigue damage and failure of glass/epoxy composite

    NASA Astrophysics Data System (ADS)

    Wang, Feng

    2007-12-01

    Fiber composites used in advanced mechanical systems are generally subjected to cyclic loading with multiaxial stress state. Thus multiaxial fatigue is a subject of major importance in design and evaluation of long-term performance of composite structures and components. Theoretical work was initially performed to address the fundamental issues of damage evolution and material degradation in glass/epoxy composites subject to multiaxial cyclic stresses. A continuum damage mechanics formulation based on irreversible thermodynamics was used to construct multiaxial cyclic constitutive equations of the composite. With coupling of damage anisotropy and multiaxial stress state and using Gibb's free energy function, damage driving force was determined. Based on the second principle of thermodynamics, evolution equations were also obtained to describe the change of the damage state in the composite under multiaxial fatigue loading. A newly introduced failure-life theory was employed for the fiber composite, based on anisotropic nature of composite strength property and distinct mechanisms of microcrack formation and growth under different multiaxial cyclic stresses. A driving force for fatigue failure was formulated with a governing function, involving combined cyclic shear and transverse tensile stresses along the weakest principal material plane of the composite. Multiaxial fatigue life of the composite was related to the forcing function using a power-law. A formulation of thermomechanical response of a fiber composite based on the general thermodynamics theory was proposed to establish a model that can couple water sorption, applied stress and damage in the composite. Starting from general Gibbs free energy, constitutive equations, which describe the relationships between state variables and corresponding driving forces, were derived. The evolution laws that describe relationships of damage driving force-damage evolution and chemical potential gradient-water flux were also given. Critical multiaxial fatigue experiments were conducted on filament-wound glass/epoxy composite tubular specimens to characterize the damage initiation and evolution. At the same time, experiment data were also been used to determine the material and multiaxial stress parameters of the fatigue-life laws for the composite and to demonstrate the validity of the theory.

  5. The Role of Elastic and Plastic Anisotropy of Sn in Recrystallization and Damage Evolution During Thermal Cycling in SAC305 Solder Joints

    SciTech Connect

    Bieler, Thomas R.; Zhou, Bite; Blair, Lauren; Zamiri, Amir; Darbandi, Payam; Pourboghrat, Farhang; Lee, Tae-Kyu; Liu, Kuo-Chuan

    2013-04-08

    Because failures in lead-free solder joints occur at locations other than the most highly shear-strained regions, reliability prediction is challenging. To gain physical understanding of this phenomenon, physically based understanding of how elastic and plastic deformation anisotropy affect microstructural evolution during thermomechanical cycling is necessary. Upon solidification, SAC305 (Sn-3.0Ag-0.5Cu) solder joints are usually single or tricrystals. The evolution of microstructures and properties is characterized statistically using optical and orientation imaging microscopy. In situ synchrotron x-ray measurements during thermal cycling are used to examine how crystal orientation and thermal cycling history change strain history. Extensive characterization of a low-stress plastic ball grid array (PBGA) package design at different stages of cycling history is compared with preliminary experiments using higher-stress package designs. With time and thermal history, microstructural evolution occurs mostly from continuous recrystallization and particle coarsening that is unique to each joint, because of the specific interaction between local thermal and displacement boundary conditions and the strong anisotropic elastic, plastic, expansion, and diffusional properties of Sn crystals. The rate of development of recrystallized microstructures is a strong function of strain and aging. Cracks form at recrystallized (random) boundaries, and then percolate through recrystallized regions. Complications arising from electromigration and corrosion are also considered.

  6. Property Evaluation and Damage Evolution of Environmental Barrier Coatings and Environmental Barrier Coated SiC/SiC Ceramic Matrix Composite Sub-Elements

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Halbig, Michael; Jaskowiak, Martha; Hurst, Janet; Bhatt, Ram; Fox, Dennis S.

    2014-01-01

    This paper describes recent development of environmental barrier coatings on SiC/SiC ceramic matrix composites. The creep and fatigue behavior at aggressive long-term high temperature conditions have been evaluated and highlighted. Thermal conductivity and high thermal gradient cyclic durability of environmental barrier coatings have been evaluated. The damage accumulation and complex stress-strain behavior environmental barrier coatings on SiCSiC ceramic matrix composite turbine airfoil subelements during the thermal cyclic and fatigue testing of have been also reported.

  7. Matrix metaloproteinases activity during the evolution of hypoxic-ischemic brain damage in the immature rat. The effect of 1-methylnicotinamide (MNA).

    PubMed

    Dragun, P; Makarewicz, D; Wójcik, L; Ziemka-Nałecz, M; Słomka, M; Zalewska, T

    2008-09-01

    Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that degrade the extracellular matrix and carry out key functions during brain development. Apart from a physiological role, excessive activation of MMPs in brain tissue has been postulated to represent a pathway for cell death arising from ischemia. To evaluate the possible involvement of MMPs in the perinatal brain asphyxia, we exposed 7-day-old rats to hypoxia-ischemia (HI). Unilateral HI was administered by ligation of the common carotid artery followed by hypoxia (7.4% O2/92.6% N2) for 65 minutes. This insult is known to produce brain damage confined to the cerebral hemisphere ipsilateral to the arterial occlusion in > 90% of animals. HI resulted in a significant elevation of MMP-2 and MMP-9 activity in the ipsilateral forebrain. The maximum activation was found at 48 hours and 7-14 days after the insult. These results suggest that early and late induction of MMPs may play a role in neuronal death as well as in repair processes. The treatment of animals subjected to HI with 1-methylnicotinamide (MNA), the anti-inflammatory agent, led to the inhibition of MMP-9 in an acute phase of ischemic damage and to the activation of MMP-2 in the later stages after injury. The timing of MMPs modulation by MNA may indicate its possible therapeutic implications. PMID:18953089

  8. Exact law of live nature

    NASA Astrophysics Data System (ADS)

    Azbel‧, Mark Ya.

    2005-08-01

    The exact law of mortality dynamics in changing populations and environment is derived. It includes no explicit characteristics of animal-environment interactions (metabolism, etc.) which are a must for life; it is universal for all animals, from single-cell yeast to humans, with their drastically different biology, evolutionary history, and complexity; it is rapidly (within few percent of life span) reversible. Such a law is unique for live systems with their homeostatic self-adjustment to environment (cf. thermodynamics of liquids and glasses). The law which is valid for all live, and only live, systems is their specific natural law. Mortality is an instrument of natural selection and biological diversity. Its law, which is preserved in evolution of all species, is a conservation law of mortality, selection, evolution, biology. The law implies new kinds of intrinsic mortality and adaptation which dominate in evolutionary unprecedented protected populations and, in contrast to species-specific natural selection, proceed via universal stepwise rungs and reduce to universal cellular mechanism. The law demonstrates that intrinsic mortality and at least certain aspects of aging are disposable evolutionary byproducts, and directed genetic and/or biological changes may yield healthy and vital Methuselah lifespan. This is consistent with experiments. Universality implies that single-cell yeast may provide a master key to the cellular mechanism of universal mortality, aging, selection, evolution, and its regulation in all animals. One may look for its manifestations in animal cells also, e.g., in their replicative senescence and cancer. Evolutionary origin and genetic nature of universality are suggested.

  9. Law in Wyoming.

    ERIC Educational Resources Information Center

    Wyoming Law-Related Education Advisory Council, Cheyenne.

    This document is intended to give students an overview of laws in Wyoming. Subjects covered include civil and criminal law; courts in Wyoming; juvenile law, juvenile court procedure; rights of children; family law; employment law; automobile-related law; laws affecting the schools; and citizenship rights and responsibilities. The laws and courts…

  10. School Law.

    ERIC Educational Resources Information Center

    Splitt, David A.

    1987-01-01

    The United States Supreme Court upheld a California state law requiring employers to allow a pregnant woman up to four months of unpaid maternity leave if she claims pregnancy as a disability. A bill before Congress addresses parental leave and job protection for parents caring for a new baby or a sick child. (MLH)

  11. School Law.

    ERIC Educational Resources Information Center

    Splitt, David A.

    1986-01-01

    Reviews four recent court decisions affecting school law. A Circuit Court of Appeals ruling upheld Norfolk Schools' decision to abolish busing and reinstate neighborhood schools. The United States Supreme Court dismissed appeals to lower court decisions involving a minimum grade prerequisite, a teacher's privacy rights, and an "adult" movie…

  12. School Law

    ERIC Educational Resources Information Center

    Splitt, David A.

    1987-01-01

    Forecasts no major surprises during the U.S. Supreme Court's 1987-88 term. Like the "Edwards v. Aguillard" ruling against Louisiana's creation science law, upcoming decisions concerning religious issues (controversial textbooks and moments of silence) and free speech (language use and controversial subject matter in student publications) will

  13. School Law.

    ERIC Educational Resources Information Center

    Splitt, David A.

    1982-01-01

    Summarizes three current issues in school law, including school district suits over potentially carcinogenic asbestos insulation, a California judge's finding that captionless educational television discriminates against hearing-impaired students, and the federal government's attempt to keep the Fairfax (Virginia) school system from charging…

  14. Consequences of the Thermal Transient on the Evolution of the Damaged Zone Around a Repository for Heat-Emitting High-Level Radioactive Waste in a Clay Formation: a Performance Assessment Perspective

    NASA Astrophysics Data System (ADS)

    Yu, Li; Weetjens, Eef; Sillen, Xavier; Vietor, Tim; Li, Xiangling; Delage, Pierre; Labiouse, Vincent; Charlier, Robert

    2014-01-01

    A proper evaluation of the perturbations of the host rock induced by the excavation and the emplacement of exothermic wastes is essential for the assessment of the long-term safety of high-level radioactive waste disposals in clay formations. The impact of the thermal transient on the evolution of the damaged zone (DZ) has been explored in the European Commission project TIMODAZ (thermal impact on the damaged zone around a radioactive waste disposal in clay host rocks, 2006-2010). This paper integrates the scientific results of the TIMODAZ project from a performance assessment (PA) point of view, showing how these results support and justify key PA assumptions and the values of PA model parameters. This paper also contextualises the significance of the thermal impact on the DZ from a safety case perspective, highlighting how the project outcomes result into an improved understanding of the thermo-hydro-mechanical behaviour of the clay host rocks. The results obtained in the TIMODAZ project strengthen the assessment basis of the safety evaluation of the current repository designs. There was no evidence throughout the TIMODAZ experimental observations of a temperature-induced additional opening of fractures nor of a significant permeability increase of the DZ. Instead, thermally induced plasticity, swelling and creep seem to be beneficial to the sealing of fractures and to the recovery of a very low permeability in the DZ, close to that of an undisturbed clay host rock. Results from the TIMODAZ project indicate that the favourable properties of the clay host rock, which guarantee the effectiveness of the safety functions of the repository system, are expected to be maintained after the heating-cooling cycle. Hence, the basic assumptions usually made in PA calculations so far are expected to remain valid, and the performance of the system should not be affected in a negative way by the thermal evolution of the DZ around a radioactive waste repository in clay host rock.

  15. Undermining Evolution: Where State Standards Go Wrong

    ERIC Educational Resources Information Center

    American Educator, 2012

    2012-01-01

    While many states are handling evolution better today than in the past, anti-evolution pressures continue to threaten state science standards. In April 2012, for example, Tennessee passed a law that enables teachers to bring anti-evolution materials into the classroom without being challenged by administrators. This law is similar to the Science…

  16. [Disability and damage of integrity].

    PubMed

    Baumann, H E

    1993-05-01

    A Swiss ophthalmologist should at minimum be aware, that, according to insurance law, these two technical terms are not identical. Some details of legal principles have to be known if being an expert for insurance or court of justice. Damage of integrity is related to the immaterial, permanent and significant reduction in physical or mental integrity, whereas invalidity relates exclusively to economic damage as a consequence of a permanent or temporary reduction of income due to accident or occupational disease; as a consequence the level of any invalidity pension is not directly related to the medically defined damage of integrity. PMID:8377399

  17. Flexure with Damage

    NASA Astrophysics Data System (ADS)

    Manaker, D. M.; Turcotte, D. L.; Kellogg, L. H.; Lyzenga, G. A.

    2004-12-01

    Investigations in structural geology and geophysics often apply continuum mechanics to solve problems relating to the deformation of the crust and lithosphere, such as the bending of strata due to a laccolith, bending of the lithosphere under island chains, bending of the lithosphere at an ocean trench. These solutions are largely based on linear elasticity. However, many processes involve stresses that exceed the elastic limit. Thus plastic, as well as elastic, deformation occurs. The temporal and spatial changes in material rheology and the nonlinear nature of the process preclude the development of analytical solutions in these complex cases. To account for the evolving rheology, we apply continuum damage mechanics as an empirical method to solve the problem of a bending beam. We use a numerical method to obtain quasi-static solutions to the Navier equation. We use the program GeoFEST v 4.5 (Geophysical Finite Element Simulation Tool), developed by NASA Jet Propulsion Laboratory, to generate solutions for each time step. Where the Von Mises stresses exceed the critical stress, we apply damage to the elements and reduce the shear modulus of the element. Damage is calculated for each time step by a power law relationship of the ratio of the critical stress to the Von Mises stress and the critical strain to the Von Mises strain, accounting for relaxation of the material due to increasing damage. To test our method, we apply damage rheology to a 2-D simple beam deforming under its own weight. This problem can be considered an analog for folding. Where stresses exceed the critical stress, we simulate the formation of damage and observe the time-dependent relaxation of the stress and strain to levels below the plastic limit. Thus damage can be used as a proxy for irreversible deformation in the fold hinge area, representing brittle fracture and microcracking where extensional fiber stresses dominate, and material dissolution where compressional fiber stresses dominate.

  18. Stigma law.

    PubMed

    1998-10-30

    Massachusetts enacted a law, called House No. 2099, that relieves real estate brokers from liability for not disclosing the history of a property to a potential buyer. The statute says that certain information does not need to be disclosed in a real estate transaction. Such information includes whether any previous occupants had HIV/AIDS or any other disease that is unlikely to be transmitted casually. PMID:11366009

  19. Characterization of creep and creep damage by in-situ microtomography

    NASA Astrophysics Data System (ADS)

    Borbély, András; Dzieciol, Krzysztof; Sket, Federico; Isaac, Augusta; di Michiel, Marco; Buslaps, Thomas; Kaysser-Pyzalla, Anke R.

    2011-07-01

    Application of in-situ microtomography to characterization of power law creep and creep damage in structural materials is presented. It is shown first that the successively reconstructed volumes are adequately monitoring the macroscopic sample shape and that microtomography is an optimal tool to characterize inhomogeneous specimen deformation. Based on a two-step image correlation technique the evolution of single voids is revealed and the basis of a pioneering approach to creep damage studies is presented. The method allows the unequivocal separation of three concurrent damage mechanisms: nucleation, growth, and coalescence of voids. The results indicate that growth rate of voids with equivalent diameters in the range of 2-5 mm is of about one order of magnitude higher than the prediction of continuum solid mechanics. Analysis of void coalescence points out the presence of two stable growth regimes related to coalescence between primary and secondary voids, respectively.

  20. DNA damage checkpoint, damage repair, and genome stability.

    PubMed

    Liu, Wei-Feng; Yu, Shan-Shan; Chen, Guan-Jun; Li, Yue-Zhong

    2006-05-01

    Genomic DNA is under constant attack from both endogenous and exogenous sources of DNA damaging agents. Without proper care, the ensuing DNA damages would lead to alteration of genomic structure thus affecting the faithful transmission of genetic information. During the process of evolution, organisms have acquired a series of mechanisms responding to and repairing DNA damage, thus assuring the maintenance of genome stability and faithful transmission of genetic information. DNA damage checkpoint is one such important mechanism by which, in the face of DNA damage, a cell can respond to amplified damage signals, either by actively halting the cell cycle until it ensures that critical processes such as DNA replication or mitosis are complete or by initiating apoptosis as a last resort. Over the last decade, complex hierarchical interactions between the key components like ATM/ATR in the checkpoint pathway and various other mediators, effectors including DNA damage repair proteins have begun to emerge. In the meantime, an intimate relationship between mechanisms of damage checkpoint pathway, DNA damage repair, and genome stability was also uncovered. Reviewed herein are the recent findings on both the mechanisms of activation of checkpoint pathways and their coordination with DNA damage repair machinery as well as their effect on genomic integrity. PMID:16722332

  1. Effect of the order of He+ and H+ ion co-implantation on damage generation and thermal evolution of complexes, platelets, and blisters in silicon

    NASA Astrophysics Data System (ADS)

    Daghbouj, N.; Cherkashin, N.; Darras, F.-X.; Paillard, V.; Fnaiech, M.; Claverie, A.

    2016-04-01

    Hydrogen and helium co-implantation is nowadays used to efficiently transfer thin Si layers and fabricate silicon on insulator wafers for the microelectronic industry. The synergy between the two implants which is reflected through the dramatic reduction of the total fluence needed to fracture silicon has been reported to be strongly influenced by the implantation order. Contradictory conclusions on the mechanisms involved in the formation and thermal evolution of defects and complexes have been drawn. In this work, we have experimentally studied in detail the characteristics of Si samples co-implanted with He and H, comparing the defects which are formed following each implantation and after annealing. We show that the second implant always ballistically destroys the stable defects and complexes formed after the first implant and that the redistribution of these point defects among new complexes drives the final difference observed in the samples after annealing. When H is implanted first, He precipitates in the form of nano-bubbles and agglomerates within H-related platelets and nano-cracks. When He is implanted first, the whole He fluence is ultimately used to pressurize H-related platelets which quickly evolve into micro-cracks and surface blisters. We provide detailed scenarios describing the atomic mechanisms involved during and after co-implantation and annealing which well-explain our results and the reasons for the apparent contradictions reported at the state of the art.

  2. Full-Scale Prestress Loss Monitoring of Damaged RC Structures Using Distributed Optical Fiber Sensing Technology

    PubMed Central

    Lan, Chunguang; Zhou, Zhi; Ou, Jinping

    2012-01-01

    For the safety of prestressed structures, prestress loss is a critical issue that will increase with structural damage, so it is necessary to investigate prestress loss of prestressed structures under different damage scenarios. Unfortunately, to date, no qualified techniques are available due to difficulty for sensors to survive in harsh construction environments of long service life and large span. In this paper, a novel smart steel strand based on the Brillouin optical time domain analysis (BOTDA) sensing technique was designed and manufactured, and then series of tests were used to characterize properties of the smart steel strands. Based on prestress loss principle analysis of damaged structures, laboratory tests of two similar beams with different damages were used to verify the concept of full-scale prestress loss monitoring of damaged reinforced concrete (RC) beams by using the smart steel strands. The prestress losses obtained from the Brillouin sensors are compared with that from conventional sensors, which provided the evolution law of prestress losses of damaged RC beams. The monitoring results from the proposed smart strand can reveal both spatial distribution and time history of prestress losses of damaged RC beams. PMID:22778590

  3. Elastic-Plastic Constitutive Equation of WC-Co Cemented Carbides with Anisotropic Damage

    NASA Astrophysics Data System (ADS)

    Hayakawa, Kunio; Nakamura, Tamotsu; Tanaka, Shigekazu

    2007-05-01

    Elastic-plastic constitutive equation of WC-Co cemented carbides with anisotropic damage is proposed to predict a precise service life of cold forging tools. A 2nd rank symmetric tensor damage tensor is introduced in order to express the stress unilaterality; a salient difference in uniaxial behavior between tension and compression. The conventional framework of irreversible thermodynamics is used to derive the constitutive equation. The Gibbs potential is formulated as a function of stress, damage tensor, isotropic hardening variable and kinematic hardening variable. The elastic-damage constitutive equation, conjugate forces of damage, isotropic hardening and kinematic hardening variable is derived from the potential. For the kinematic hardening variable, the superposition of three kinematic hardening laws is employed in order to improve the cyclic behavior of the material. For the evolution equation of the damage tensor, the damage is assumed to progress by fracture of the Co matrix — WC particle interface and by the mechanism of fatigue, i.e. the accumulation of microscopic plastic strain in matrix and particles. By using the constitutive equations, calculation of uniaxial tensile and compressive test is performed and the results are compared with the experimental ones in the literature. Furthermore, finite element analysis on cold forward extrusion was carried out, in which the proposed constitutive equation was employed as die insert material.

  4. Elastic-Plastic Constitutive Equation of WC-Co Cemented Carbides with Anisotropic Damage

    SciTech Connect

    Hayakawa, Kunio; Nakamura, Tamotsu; Tanaka, Shigekazu

    2007-05-17

    Elastic-plastic constitutive equation of WC-Co cemented carbides with anisotropic damage is proposed to predict a precise service life of cold forging tools. A 2nd rank symmetric tensor damage tensor is introduced in order to express the stress unilaterality; a salient difference in uniaxial behavior between tension and compression. The conventional framework of irreversible thermodynamics is used to derive the constitutive equation. The Gibbs potential is formulated as a function of stress, damage tensor, isotropic hardening variable and kinematic hardening variable. The elastic-damage constitutive equation, conjugate forces of damage, isotropic hardening and kinematic hardening variable is derived from the potential. For the kinematic hardening variable, the superposition of three kinematic hardening laws is employed in order to improve the cyclic behavior of the material. For the evolution equation of the damage tensor, the damage is assumed to progress by fracture of the Co matrix - WC particle interface and by the mechanism of fatigue, i.e. the accumulation of microscopic plastic strain in matrix and particles. By using the constitutive equations, calculation of uniaxial tensile and compressive test is performed and the results are compared with the experimental ones in the literature. Furthermore, finite element analysis on cold forward extrusion was carried out, in which the proposed constitutive equation was employed as die insert material.

  5. Full-scale prestress loss monitoring of damaged RC structures using distributed optical fiber sensing technology.

    PubMed

    Lan, Chunguang; Zhou, Zhi; Ou, Jinping

    2012-01-01

    For the safety of prestressed structures, prestress loss is a critical issue that will increase with structural damage, so it is necessary to investigate prestress loss of prestressed structures under different damage scenarios. Unfortunately, to date, no qualified techniques are available due to difficulty for sensors to survive in harsh construction environments of long service life and large span. In this paper, a novel smart steel strand based on the Brillouin optical time domain analysis (BOTDA) sensing technique was designed and manufactured, and then series of tests were used to characterize properties of the smart steel strands. Based on prestress loss principle analysis of damaged structures, laboratory tests of two similar beams with different damages were used to verify the concept of full-scale prestress loss monitoring of damaged reinforced concrete (RC) beams by using the smart steel strands. The prestress losses obtained from the Brillouin sensors are compared with that from conventional sensors, which provided the evolution law of prestress losses of damaged RC beams. The monitoring results from the proposed smart strand can reveal both spatial distribution and time history of prestress losses of damaged RC beams. PMID:22778590

  6. Congenital ureteropelvic junction obstruction: physiopathology, decoupling of tout court pelvic dilatation-obstruction semantic connection, biomarkers to predict renal damage evolution.

    PubMed

    Alberti, C

    2012-02-01

    The widespread use of fetal ultrasonography results in a frequent antenatally observation of hydronephrosis, ureteropelvic junction obstruction (UPJO) accounting for the greatest fraction of congenital obstructive nephropathy. UPJO may be considered, in most cases, as a functional obstructive condition, depending on defective fetal smooth muscle/nerve development at this level, with lack of peristaltic wave propagation--aperistaltic segment--and, therefore, poor urine ejection from the renal pelvis into the ureter. The UPJO-related physiopathologic events are, at first, the compliant dilatation of renal pelvis that, acting as hydraulic buffer, protects the renal parenchyma from the rising intrapelvic pressure-related potential damages, and, subsequently, beyond such phase of dynamic balance, the tubular cell stretch-stress induced by increased intratubular pressure and following parenchymal inflammatory lesions: inflammatory infiltrates, fibroblast proliferation, activation of myofibroblasts, tubulo-interstitial fibrosis. Reactive oxygen species (ROS), nitric oxide (NO), several chemo- and cytokines, growth factors, prostaglandins and eicosanoids, angiotensin-II are the main pathogenetic mediators of the obstructive nephropathy. Apoptosis of tubular cells is the major cause of the tubular atrophy, together with epithelial-mesenchymal transdifferentiation. Some criticisms on tout court semantic renal pelvis dilatation-obstruction connection have been raised considering that the renal pelvis expansion isn't, in any case, linked to an ostructive condition, as it may be verified by diuretic (furosemide) renogram together with scintiscan-based evaluation of differential renal function. In this regard, rather than repetitive invasive nuclear procedures that expose the children to ionizing radiations, an intriguing noninvasive strategy, based on the evaluation of urinary biomarkers and urinary proteome, can define the UPJO-related possible progress of parenchymal lesions, thus predicting which patients must require an obstruction correcting surgery and in which patients, instead, the hydronephrosis will spontaneously resolve. PMID:22428472

  7. 45 CFR 164.412 - Law enforcement delay.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... § 164.412 Law enforcement delay. If a law enforcement official states to a covered entity or business... 45 Public Welfare 1 2011-10-01 2011-10-01 false Law enforcement delay. 164.412 Section 164.412... investigation or cause damage to national security, a covered entity or business associate shall: (a) If...

  8. 45 CFR 164.412 - Law enforcement delay.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... § 164.412 Law enforcement delay. If a law enforcement official states to a covered entity or business... 45 Public Welfare 1 2014-10-01 2014-10-01 false Law enforcement delay. 164.412 Section 164.412... investigation or cause damage to national security, a covered entity or business associate shall: (a) If...

  9. 45 CFR 164.412 - Law enforcement delay.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... § 164.412 Law enforcement delay. If a law enforcement official states to a covered entity or business... 45 Public Welfare 1 2012-10-01 2012-10-01 false Law enforcement delay. 164.412 Section 164.412... investigation or cause damage to national security, a covered entity or business associate shall: (a) If...

  10. 45 CFR 164.412 - Law enforcement delay.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... § 164.412 Law enforcement delay. If a law enforcement official states to a covered entity or business... 45 Public Welfare 1 2013-10-01 2013-10-01 false Law enforcement delay. 164.412 Section 164.412... investigation or cause damage to national security, a covered entity or business associate shall: (a) If...

  11. Bullard's Law

    NASA Astrophysics Data System (ADS)

    Sclater, J. G.

    2002-12-01

    The first scientist to measure heat flow through the floor of the oceans systematically, Teddy Bullard had received his Ph D in the thirties as a nuclear physicist under Rutherford at Cambridge University. Immediately before WWII and then entirely thereafter, Teddy Bullard devoted himself to better understanding the Earth, ending his career as the Head of the Department of Geodesy and Geophysics at Cambridge. However, he sometimes regretted that he had had to abandon nuclear physics to find a job. He especially bemoaned the fact that unlike, most of his contemporaries from the Cavendish, he had had no important physical law named after him. To rectify this oversight Maurice Hill, the leader of the marine group at the Department, formulated what came to be known Bullard's Law - "Never take a second heat flow measurement within 20 km of the original for fear that it differ from the first by two orders of magnitude". In this presentation, I review the background information that led to Bullard's Law, to the realization that the early workers (1949 - 1965: Maxwell, Von Herzen, Bullard, Day, Langseth, Gerard, Uyeda, Yasui, Vacquier, Reitzel, Nason and Lee amongst others) had measured the heat flow correctly and that they had observed a large but real variability in heat flow near the crest of the mid-ocean ridges. I discuss the early attempts to explain the variability, and, the various sedimentary observations (Skornyakova, Arrhenius, Bonatti and Bostrom), magnetic measurements (Irving) and physical inferences (Elder and Lister) that led to the realization that fluid flowing through the oceanic crust might have created the variability. I finish by discussing an expedition to the Galapagos Spreading Center where NSF funded Dick Von Herzen and I to prove Lister wrong. Instead our graduate student Dave Williams, to my surprise but not Dick's, observed the first deep sea hydrothermal plume. The rest is history.

  12. On Common Ground: Jost's (1897) Law of Forgetting and Ribot's (1881) Law of Retrograde Amnesia

    ERIC Educational Resources Information Center

    Wixted, John T.

    2004-01-01

    T. Ribot's (1881) law of retrograde amnesia states that brain damage impairs recently formed memories to a greater extent than older memories, which is generally taken to imply that memories need time to consolidate. A. Jost's (1897) law of forgetting states that if 2 memories are of the same strength but different ages, the older will decay more…

  13. 43 CFR 9239.1-3 - Measure of damages.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Measure of damages. 9239.1-3 Section 9239... Measure of damages. (a) Unless State law provides stricter penalties, in which case the State law shall...) The provisions of paragraph (a) of this section shall not be deemed to limit the measure of...

  14. A Grained Continuum Theory of Damage and Coarsening

    NASA Astrophysics Data System (ADS)

    Bercovici, D.; Ricard, Y.

    2005-12-01

    Formation of tectonic plate boundaries from mantle and lithosphere dynamics involves shear localization during deformation as well as remnant weak zones after deformation ceases. The requisite state variable that delineates the weak zone could be, for example, increased temperature or water content, although a well documented feature of lithospheric weak zones is reduced grainsize (i.e., mylonites). Grainsize reduction is typically attributed to dynamic recrystallization although the models arising from this hypothesis are problematic: grainsize reduction occurs during dislocation creep while the rheological effect of grainsize occurs in diffusion creep and these creep mechanisms exist in different stress regimes. Moreover, the grain-growth ("healing") laws employed for these models assume static grain-growth or coarsening, although the setting itself is far from static or equilibrium. Here we present a new grained-continuum theory for simultaneous and competing coarsening and grainsize reduction through a "damage" mechanics and nonequilibrium thermodynamics approach. The theory contains coupled grainsize/statistical and continuum/macroscopic components. The grainsize/statistical element of the theory prescribes the evolution of the grainsize distribution through space and time, and a kinetic phenomenological (i.e., nonequilibrium thermodynamic) law for how grainzize changes depending on free energy differences between grains, including both grain-boundary surface energy (which controls coarsening) and the contribution of deformational work to these free energies (which controls damage). The continuum level of the theory considers standard mass, momentum and energy conservation on the statistically averaged grained continuum; however, the continuum treatment of energy conservation and entropy-source positivity provide the phenomenological law for the statistical grain-growth law. A fundamental thermodynamic requirement arising from the theory is that deformational work must always cause large grains to shrink and small ones to grow, causing the grainsize distribution to propagate to smaller grainsizes and thus to mean grainsize reduction. The theory also captures the essential static-coarsening predictions of self-similar grainsize distributions from Lifshitz-Slyosov and Hillert theories. However, with the inclusion of nonstatic/nonequilibrium conditions such as damage and deformational work, the theory also predicts a range of self-similar and non-self-similar (even singular) grainsize distribution evolutions involving either coarsening or grainsize reduction and shear localization.

  15. Administrative Law: The Hidden Comparative Law Course.

    ERIC Educational Resources Information Center

    Strauss, Peter L.

    1996-01-01

    Argues that the main contribution of the Administrative Law course to law students is that it presents problems which contrast with those of the standard court-centered curriculum and can illuminate other areas of law, repeatedly confronting students with doctrinal differences. Offers several examples from civil procedure, constitutional law, and…

  16. Fractional order viscoelasticity and theoretical progress in rheological constitutive law for rocks

    NASA Astrophysics Data System (ADS)

    Kawada, Y.; Yajima, T.; Nagahama, H.

    2010-12-01

    Fractional calculus has recently become an important tool in the analysis of relaxation phenomena, such as stress-strain relationships in composite materials. This is because the memory effect, an essence of viscoelasticity, cannot be entirely described by the empirical constitutive equations with the integer-order time derivative. We derive a generalized viscoelastic constitutive equation from an energy function with fractional-order time derivatives. The constitutive equation reduces the empirical models of viscoelasticity such as Maxwell, Kelvin-Voigt and Zener models and represents the relaxation behavior of any kind of viscoelastic materials such as polymer, metal and rocks, enabling us to investigate the time-dependent property of relaxation and the origin of power-law dynamics. The constitutive equation is a differential equation with fractional order, and taking the Laplace transformations yield solutions with the Mittag-Leffler function having the asymptotic behavior of temporal power-law. The constitutive equation is hence equivalent to the Boltzmann superposition integral (a definition of the viscoelastic behavior) with power-law kernel, i.e., the Green’s function exhibiting temporal power-law relaxation, and in its special case, the kernel becomes an exponential function having a characteristic time. We also analyze experimental data sets on the deformation of rocks such as halite and lherzolite exhibiting the empirical flow-law (the power-law scaling between bulk stress and strain-rate) and show that the behaviors can be described by the viscoelastic constitutive equation with fractional-order derivatives as well. The order of fractional derivative is identical to the reciprocal of stress exponent of flow law reflecting the memory effect in viscoelasticity and the deformation mechanisms of rocks. It is also denoted that the power-law scaling in viscoelastic behavior of rocks is related to aspects of crustal fluid dynamics and change in atmospheric radon concentration associated with damage evolution prior to catastrophic failure (analogous to an earthquake).

  17. A methodology to predict creep life for advanced ceramics using continuum damage mechanics

    SciTech Connect

    Chuang, T.J.; Duffy, S.F.

    1994-01-01

    A methodology is proposed to estimate creep rupture life for advanced ceramics such as continuous fiber reinforced ceramic matrix composites (CFCMC). Based on the premise that the damage pattern takes the form of a heterogeneous distribution of grain boundary cavities in the majority of creep life, a damage parameter is incorporated in various creep strain rate equations. The resulting constitutive equations for creep strain and accumulated damage are cast in terms of stress, and other affinities. It is pointed out that these affinities can be derived from a scalar creep potential in non equilibrium thermodynamics. The evolutionary laws are formulated based on many micro-mechanical models. The time-dependent reliability or hazard rate for a SiC is then established by damage mechanics with Weibull analysis. A unit cell model is presented for predicting life of a uni-directional CFCMC subjected to a constant far-field stress. A system of coupled flrst order ordinary differential equations is derived from which the evolution of creep damage can be solved giving the rupture life. It is shown that the stress dependence on the lifetime is very sensitive to the type of damage mechanisms active at the microstructural level.

  18. Analysing the Law of Dynamic Subsidence in Mining Area by Fusing Insar and Leveling Measurements

    NASA Astrophysics Data System (ADS)

    Yang, Z. F.; Li, Z. W.; Zhu, J. J.; Hu, J.; Wang, Y. J.; Chen, G. L.

    2013-07-01

    Understanding the law of mining surface dynamic subsidence plays an important role in protecting the villages and other infrastructures against subsidence damage and disturbance. Unfortunately, the existed methods are mostly based on a few sparse leveling measurements, the accuracy and reliability of which are degraded when the feature points of the leveling measurements are lost in the processing of subsidence evolution. This paper presents a method to analysing the law of mining surface dynamic subsidence by fusing interferometric synthetic aperture radar (InSAR) and leveling measurements. By comparing the fitted results obtained by fusing InSAR/leveling and those only by independent leveling, it is shown that the InSAR/levelling fusion not only can make up the deficiency when the leveling measurements lost the feature points of dynamic subsidence, but also can improve the accuracy and reliability of results.

  19. 32 CFR 750.69 - Measure of damages.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 5 2012-07-01 2012-07-01 false Measure of damages. 750.69 Section 750.69... Claims Not Cognizable Under Any Other Provision of Law § 750.69 Measure of damages. Generally, the measure-of-damage provisions under the MCA are used to determine the extent of recovery for...

  20. 32 CFR 750.69 - Measure of damages.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 5 2011-07-01 2011-07-01 false Measure of damages. 750.69 Section 750.69... Claims Not Cognizable Under Any Other Provision of Law § 750.69 Measure of damages. Generally, the measure-of-damage provisions under the MCA are used to determine the extent of recovery for...

  1. 32 CFR 750.69 - Measure of damages.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 5 2010-07-01 2010-07-01 false Measure of damages. 750.69 Section 750.69... Claims Not Cognizable Under Any Other Provision of Law § 750.69 Measure of damages. Generally, the measure-of-damage provisions under the MCA are used to determine the extent of recovery for...

  2. Molecular dynamics simulation of radiation damage cascades in diamond

    NASA Astrophysics Data System (ADS)

    Buchan, J. T.; Robinson, M.; Christie, H. J.; Roach, D. L.; Ross, D. K.; Marks, N. A.

    2015-06-01

    Radiation damage cascades in diamond are studied by molecular dynamics simulations employing the Environment Dependent Interaction Potential for carbon. Primary knock-on atom (PKA) energies up to 2.5 keV are considered and a uniformly distributed set of 25 initial PKA directions provide robust statistics. The simulations reveal the atomistic origins of radiation-resistance in diamond and provide a comprehensive computational analysis of cascade evolution and dynamics. As for the case of graphite, the atomic trajectories are found to have a fractal-like character, thermal spikes are absent and only isolated point defects are generated. Quantitative analysis shows that the instantaneous maximum kinetic energy decays exponentially with time, and that the timescale of the ballistic phase has a power-law dependence on PKA energy. Defect recombination is efficient and independent of PKA energy, with only 50% of displacements resulting in defects, superior to graphite where the same quantity is nearly 75%.

  3. Three-dimensional cohesive modeling of impact damage of composites

    NASA Astrophysics Data System (ADS)

    Yu, Chengxiang

    The objective of this work is to establish the applicability of cohesive theories of fracture in situations involving material interface, material heterogeneity (e.g., layered composites), material anisotropy (e.g., fiber-reinforced composites), shear cracks, intersonic dynamic crack growth and dynamic crack branching. The widely used cohesive model is extended to orthotropic range. The so-developed computational tool, completed by a self-adaptive fracture procedure and a frictional contact algorithm, is capable of following the evolution of three-dimensional damage processes, modeling the progressive decohesion of interfaces and anisotropic materials. The material parameters required by cohesive laws are directly obtained from static experiments. The ability of the methodology to simulate diverse problems such as delamination between fibers of graphite/epoxy composites, as well as sandwich structures and branching within brittle bulk materials has been demonstrated.

  4. Right Hemisphere Brain Damage

    MedlinePlus

    ... Language and Swallowing / Disorders and Diseases Right Hemisphere Brain Damage [ en Español ] What is right hemisphere brain ... right hemisphere brain damage ? What is right hemisphere brain damage? Right hemisphere brain damage (RHD) is damage ...

  5. Demonstrating the Gas Laws.

    ERIC Educational Resources Information Center

    Holko, David A.

    1982-01-01

    Presents a complete computer program demonstrating the relationship between volume/pressure for Boyle's Law, volume/temperature for Charles' Law, and volume/moles of gas for Avagadro's Law. The programing reinforces students' application of gas laws and equates a simulated moving piston to theoretical values derived using the ideal gas law.…

  6. Inclusion and the Law.

    ERIC Educational Resources Information Center

    Damer, Linda K.

    2001-01-01

    Describe four different laws related to the education of children with disabilities: (1) Public Law 94-142; (2) Public Law 99-457; (3) Public Law 101-336 ADA; and (4) Public Law 101-476 IDEA. Discusses the topic of mainstreaming and highlights the recent legal decisions that have occurred. (CMK)

  7. Demonstrating the Gas Laws.

    ERIC Educational Resources Information Center

    Holko, David A.

    1982-01-01

    Presents a complete computer program demonstrating the relationship between volume/pressure for Boyle's Law, volume/temperature for Charles' Law, and volume/moles of gas for Avagadro's Law. The programing reinforces students' application of gas laws and equates a simulated moving piston to theoretical values derived using the ideal gas law.

  8. A continuum damage model of fatigue-induced damage in laminated composites

    NASA Technical Reports Server (NTRS)

    Harris, Charles E.; Allen, David H.

    1988-01-01

    A model is presented which predicts the stress-strain behavior of continuous fiber reinforced laminated composites in the presence of microstructural damage. The model is based on the concept of continuum damage mechanics and uses internal state variables to characterize the various damage modes. The associated internal state variable growth laws are mathematical models of the loading history induced development of microstructural damage. The model is demonstrated by using it to predict the response of damaged AS-4/3502 graphite/epoxy laminate panels.

  9. Evolution of internal variables in an expanding hollow cylinder at large plastic strains.

    PubMed

    Alexandrov, Sergei; Dinh Kien, Nguyen; Erisov, Yaroslav; Grechnikov, Fedor

    2016-01-01

    An efficient method for calculating the evolution of internal variables in an expanding hollow cylinder of rigid/plastic material is proposed. The conventional constitutive equations for rigid plastic, hardening material are supplemented with quite an arbitrary set of evolution laws for internal variables assuming that the material is incompressible. No restriction is imposed on the hardening law. The problem is solved in Lagrangian coordinates. This significantly facilitates a numerical treatment of the problem. In particular, the initial/boundary value problem is reduced to a system of equations in characteristic coordinates. A finite difference scheme is used for solving these equations. An illustrative example is presented assuming that the internal variables are the equivalent plastic strain and a damage parameter. PMID:27066385

  10. Evolution and Friendship

    ERIC Educational Resources Information Center

    Mena-Werth, Jose

    2005-01-01

    In 1925, Williams Jennings Bryan, a former congressman from Nebraska and a former Secretary of State under Woodrow Wilson, spent two agonizing weeks defending his religious faith that cost him his life a month after. Bryan was a prosecutor of high school teacher John Scopes, who had violated Tennessee state law by teaching the theory of evolution.

  11. Evolution and Friendship

    ERIC Educational Resources Information Center

    Mena-Werth, Jose

    2005-01-01

    In 1925, Williams Jennings Bryan, a former congressman from Nebraska and a former Secretary of State under Woodrow Wilson, spent two agonizing weeks defending his religious faith that cost him his life a month after. Bryan was a prosecutor of high school teacher John Scopes, who had violated Tennessee state law by teaching the theory of evolution.…

  12. CONSTITUTIVE RELATIONSHIP OF TISSUE BEHAVIOR WITH DAMAGE ACCUMULATION OF HUMAN CORTICAL BONE

    PubMed Central

    Luo, Qing; Leng, Huijie; Acuna, Rae; Dong, Xuanliang; Rong, Qiguo; Wang, Xiaodu

    2010-01-01

    Microdamage accumulation has been identified as a major conduit for bone tissues to absorb fracture energy. Due to the poor understanding of its underlying mechanism, however, an adequate constitutive relationship between damage accumulation and the mechanical behavior of bone has not yet been established. In this study, the constitutive relationship between the damage accumulation induced by overload and the evolution of mechanical properties of bone with incremental deformation was established based on the experimental results obtained from a novel progressive loading protocol developed in our laboratory. First, a decayed exponential model was proposed to capture the damage accumulation (modulus loss) with increasing applied strain. Next, a power law function was proposed to represent the progression of plastic deformation with damage accumulation. Finally, a linear combination of the Kohlrausch-Williams-Watts (KWW) function and Debye function was used to depict the viscoelastic behavior of bone associated with damage accumulation. The results of this study may help develop a constitutive model for predicting the mechanical behavior of cortical bone tissues. PMID:20472239

  13. Incorporating Micro-Mechanics Based Damage Models into Earthquake Rupture Simulations

    NASA Astrophysics Data System (ADS)

    Bhat, H.; Rosakis, A.; Sammis, C. G.

    2012-12-01

    The micromechanical damage mechanics formulated by Ashby and Sammis, 1990 and generalized by Deshpande and Evans 2008 has been extended to allow for a more generalized stress state and to incorporate an experimentally motivated new crack growth (damage evolution) law that is valid over a wide range of loading rates. This law is sensitive to both the crack tip stress field and its time derivative. Incorporating this feature produces additional strain-rate sensitivity in the constitutive response. The model is also experimentally verified by predicting the failure strength of Dionysus-Pentelicon marble over a wide range of strain rates. Model parameters determined from quasi-static experiments were used to predict the failure strength at higher loading rates. Agreement with experimental results was excellent. After this verification step the constitutive law was incorporated into a Finite Element Code focused on simulating dynamic earthquake ruptures with specific focus on the ends of the fault (fault tip process zone) and the resulting strong ground motion radiation was studied.

  14. Students and the Law.

    ERIC Educational Resources Information Center

    South Carolina State Dept. of Education, Columbia. Office of Vocational Education.

    Designed as a practical approach to the study of law, this publication offers seven lesson plans focusing on legal topics that have potential significance to high school students preparing to enter the world of work. Lesson plans address the following topics: minors and the law, automobile insurance, employment law, sports and the law, computer…

  15. Innovations in Law.

    ERIC Educational Resources Information Center

    Martz, Carlton

    2000-01-01

    This issue of "Bill of Rights in Action" looks at historical and recent innovations in law. The first article examines the code of laws developed by the ancient Hebrews which influenced Roman law, English law, and the U.S. Declaration of Independence and Constitution. The second article explores Thomas Jefferson's writing of the Declaration of…

  16. Maryland Law and Education.

    ERIC Educational Resources Information Center

    Dubel, Robert Y.

    This document analyzes the major elements of Maryland school and college law pertaining to governance. While recognizing differences between school and college law in Maryland, this study shows that there are many elements in common between the two. This study will be primarily concerned with civil law rather than criminal law. School personnel or…

  17. [Teaching about Family Law].

    ERIC Educational Resources Information Center

    Ryan, John Paul, Ed.

    1992-01-01

    This issue of "Focus on Law Studies""contains a special emphasis on teaching about law and the family", in the form of the following three articles: "Teaching Family Law: Growing Pains and All" (Susan Frelich Appleton); "The Family Goes to Court: Including Law in a Sociological Perspective on the Family" (Mary Ann Lamanna); and Michael Grossberg's

  18. Law As a Career.

    ERIC Educational Resources Information Center

    American Bar Association, Chicago, IL. Public Education Div.

    Intended as a guide for people considering a career in law, this booklet addresses the following questions: (1) "What is the lawyer's role in society?" (2) "Should you be a lawyer?" (3) "What about jobs?" (4) "How much do lawyers make?" (5) "How do you choose a law school?" (6) "How to get into law school?" (7) "What is law school like?" (8) "How…

  19. [Teaching about Family Law].

    ERIC Educational Resources Information Center

    Ryan, John Paul, Ed.

    1992-01-01

    This issue of "Focus on Law Studies""contains a special emphasis on teaching about law and the family", in the form of the following three articles: "Teaching Family Law: Growing Pains and All" (Susan Frelich Appleton); "The Family Goes to Court: Including Law in a Sociological Perspective on the Family" (Mary Ann Lamanna); and Michael Grossberg's…

  20. The Study on spall and damage in convergent geometry

    NASA Astrophysics Data System (ADS)

    Xiaoyang, Pei; Xui, Peng; Hongliang, He; Ping, Li

    2015-06-01

    Spallation damage in ductile materials is the process of void nucleation, growth and coalescence due to states of high tensile stress. Typical experiments are conducted in a planar, uniaxial stress configuration. Here, the effect of convergent geometry on the properties of dynamic damage evolution of OFHC are investigated. The spall fracture experiments are conducted using explosive generators. The damage evolution process are studied using the time-resolved free-surface velocity interferometry, post-experiment metallurgical analysis of the soft recovered samples. It indicated that, the convergent effect is a very important factors for the spallation damage, and the distinct differences are observed in the damage pattern between planar and convergent experiment.

  1. Natural resources policy and law: Trends and directions

    SciTech Connect

    MacDonnell, L.J.; Bates, S.F.

    1993-11-01

    The book explores past, present, and future directions in natural resource environmental law and policy, with a special emphasis on new laws and important legal cases of the past decade and their implications for the future. Its ten chapters, each written by a leading expert in the field, consider both specific concerns and broad themes, including topics such as history and evolution of natural resources law and policy, laws governing mining and minerals, oil and gas, and public lands, and relationship between environmentalism and environmental law, and future directions of the field.

  2. The Distinction between Civil and Criminal Law: A Lesson Plan for High School Law-Related Educators To Support "Understanding the Federal Courts."

    ERIC Educational Resources Information Center

    Administrative Office of the United States Courts, Washington, DC.

    The O. J. Simpson trials taught much of the United States a basic lesson in the difference between criminal law and civil law. Many students learn in their government classes that a person cannot be tried twice for the same crime. A person found innocent in a criminal trial, however, can be sued under civil law procedures for damages. It is…

  3. Damaged Skylab

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The Saturn V vehicle, carrying the unmarned orbital workshop for the Skylab-1 mission, lifted off successfully and all systems performed normally. Sixty-three seconds into the flight, engineers in the operation support and control center saw an unexpected telemetry indication that signalled that damages occurred on one solar array and the micrometeoroid shield during the launch. The micrometeoroid shield, a thin protective cylinder surrounding the workshop protecting it from tiny space particles and the sun's scorching heat, ripped loose from its position around the workshop. This caused the loss of one solar wing and jammed the other. Still unoccupied, the Skylab was stricken with the loss of the heat shield and sunlight beat mercilessly on the lab's sensitive skin. Internal temperatures soared, rendering the station uninhabitable, threatening foods, medicines, films, and experiments. This image, taken during a fly-around inspection by the Skylab-2 crew, shows a crippled Skylab in orbit. The crew found their home in space to be in serious shape; the heat shield gone, one solar wing gone, and the other jammed. The Marshall Space Flight Center (MSFC) developed, tested, rehearsed, and approved three repair options. These options included a parasol sunshade and a twin-pole sunshade to restore the temperature inside the workshop, and a set of metal cutting tools to free the jammed solar panel.

  4. Damaged Skylab

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The Saturn V vehicle, carrying the unmarned orbital workshop for the Skylab-1 mission, lifted off successfully and all systems performed normally. Sixty-three seconds into the flight, engineers in the operation support and control center saw an unexpected telemetry indication that signalled that damages occurred on one solar array and the micrometeoroid shield during the launch. The micrometeoroid shield, a thin protective cylinder surrounding the workshop, that protected it from tiny space particles and the sun's scorching heat, ripped loose from its position around the workshop. This caused the loss of one solar wing and jammed the other. Still unoccupied, the Skylab was stricken with the loss of the heat shield and sunlight beat mercilessly on the lab's sensitive skin. Internal temperatures soared, rendering the station uninhabitable, threatening foods, medicines, films, and experiments. This image, taken during a fly-around inspection by the Skylab-2 crew, shows the exterior skin of the workshop discolored by solar radiation. The Marshall Space Flight Center (MSFC) developed, tested, rehearsed, and approved three repair options. These options included a parasol sunshade and a twin-pole sunshade to restore the temperature inside the workshop, and a set of metal cutting tools to free the jammed solar panel.

  5. Continuum damage mechanics for sintered powder metals

    NASA Astrophysics Data System (ADS)

    Yuan, Huang; Ma, SongYun; Zhang, Long

    2015-01-01

    Sintered metals are characterized by the high porosity (? 8%) and voids/micro-cracks in microns. Inelastic behavior of the materials is coupled with micro-crack propagation and coalescence of open voids. In the present work the damage evolution of the sintered iron under multi-axial monotonic loading conditions was investigated experimentally and computationally. The tests indicated that damage of the sintered iron initiated already at a stress level much lower than the macroscopic yield stress. The damage process can be divided into the stress-dominated elastic damage and the plastic damage described by the plastic strain. Based on the uniaxial tensile tests an elastic-plastic continuum damage model was developed which predicts both elastic damage and plastic damage in the sintered iron under general multi-axial monotonic loading conditions. Computational predictions agree with experiments with different multi-axial loading paths. A phenomenological continuum damage model for the sintered metal is developed based on the experimental observations to predict the inelastic behavior and damage process to failure under multi-axial loading conditions. The proposed damage model is experimentally verified under different loading conditions.

  6. Continuum damage modeling of ice shelves: inversion of surface velocities for a state damage variable

    NASA Astrophysics Data System (ADS)

    Borstad, C.; Larour, E.; Morlighem, M.; Seroussi, H.; Rignot, E.

    2012-04-01

    Continuum damage mechanics is a promising alternative to fracture mechanics for representing rifting, crevassing and calving processes in ice sheet models. The constitutive relations describing ice rheology can be modified using state variables which describe the effects of cracking and damage without explicitly seeking to resolve individual cracks. The challenge in formulating a damage model for application in a large-scale ice sheet model is in the computational cost associated with the increase in model complexity and the addition of a differential equation describing the evolution of damage. We present an investigation of the spatial distribution of damage for the Larsen C ice shelf using a scalar isotropic damage model implemented in the Ice Sheet System Model (ISSM). The representation of damage using a single scalar is a simple but numerically efficient approach to accounting for the effects of fractures on ice flow. InSAR-derived surface velocities are used to invert for the scalar damage variable, leading to a spatial map of damage analogous to that produced by inverting for the ice rigidity itself. The key distinction in inverting for the damage variable is that thermal and mechanical components of the constitutive relation are formally separated in the inversion. This spatial mapping of damage is a key first step in forward modeling of the stability of ice shelves using damage mechanics, and we discuss ongoing work to implement a transient damage model in ISSM to project the mechanical integrity of ice shelves in a warming climate.

  7. Does Your Collective Bargaining Agreement Violate Antitrust Law?

    ERIC Educational Resources Information Center

    Bigoness, William J.; And Others

    1981-01-01

    To familiarize managers with the conditions under which collective bargaining agreements may violate antitrust law, the historical evolution of antitrust law concerning labor-management relations is traced; the managerial implications of the United States Supreme Court's decisions are discussed; and likely future trends are suggested. (Author/MLF)

  8. Cumulative creep damage for unidirectional composites under step loading

    NASA Astrophysics Data System (ADS)

    Guedes, Rui Miranda

    2012-11-01

    The creep lifetime prediction of unidirectional composite materials under step loading, based on constant loading durability diagram, is analyzed for the two-step creep loading condition. For this purpose different nonlinear cumulative-damage laws are revisited and applied to predict creep lifetime. One possible approach to accounting for damage accumulation is provided by the continuum-damage mechanics (CDM). However, the CDM lifetime expression obtained for constant loading condition presents some drawbacks. Specifically, the upper stress range is not accommodated by CDM form. A modification of CDM is proposed, forcing the CDM to capture the short-term creep failure. It is proven that this modified CDM (MCDM) does not yield the same predictions as the Linear Cumulative-damage law (Miner's law). Predictions obtained from the nonlinear cumulative-damage laws are compared against synthetic lifetime generated by a micromechanical model that simulates unidirectional composites under two-step creep loading condition. Comparable deviations from Miner's law are obtained by the nonlinear cumulative-damage laws.

  9. Gas evolution from spheres

    SciTech Connect

    Longhurst, G.R.

    1991-04-01

    Gas evolution from spherical solids or liquids where no convective processes are active is analyzed. Three problem classes are considered: (1) constant concentration boundary, (2) Henry's law (first order) boundary, and (3) Sieverts' law (second order) boundary. General expressions are derived for dimensionless times and transport parameters appropriate to each of the classes considered. However, in the second order case, the non-linearities of the problem require the presence of explicit dimensional variables in the solution. Sample problems are solved to illustrate the method. 5 refs., 4 figs.

  10. Tort law and medical malpractice insurance premiums.

    PubMed

    Kilgore, Meredith L; Morrisey, Michael A; Nelson, Leonard J

    2006-01-01

    This paper estimated the effects of tort law and insurer investment returns on physician malpractice insurance premiums. Data were collected on tort law from 1991 through 2004, and multivariate regression models, including fixed effects for state and year, were used to estimate the effect of changes in tort law on medical malpractice premiums. The premium consequences of national policy changes were simulated. The analysis found that the introduction of a new damage cap lowered malpractice premiums for internal medicine, general surgery, and obstetrics/gynecology by 17.3%, 20.7%, and 25.5%, respectively. Lowering damage caps by dollar 100,000 reduced premiums by 4%. Statutes of repose also resulted in lower premiums. No other tort law changes had the effect of lowering premiums. Simulation results indicate that a national cap of dollar 250,000 on awards for noneconomic damages in all states would imply premium savings of dollar 16.9 billion. Extending a dollar 250,000 cap to all states that do not currently have them would save dollar 1.4 billion annually, or about 8% of the total. A negative effect on malpractice premiums was found for the Dow Jones industrial average, but not for bond prices; effects of the Nasdaq index were not significant for internal medicine, but were marginally significant for surgery and obstetrics premiums. PMID:17176968

  11. Law-Related Education.

    ERIC Educational Resources Information Center

    Little, Timothy H.

    1987-01-01

    Identifies five "motives" behind law-related education. They are citizenship education, delinquency prevention, survival skills, critical thinking, and ethics education. Presents a brief survey designed to collect information about law-related education in the Michigan public schools. (JDH)

  12. Damage thresholds in laser irradiated optical materials

    SciTech Connect

    Guignard, F.; Autric, M.; Baudinaud, V.

    1997-12-01

    An experimental study on the damage induced by laser irradiation on different materials, borosilicate glass, fused silicate, moulded and stretched polymethylmethacrylate (PMMA), has been performed. The irradiation source is a 1KJ pulsed cold cathode electron gun preionized TEA CO{sub 2} laser. Damage mechanisms are controlled by the in-depth absorption of the 10,6 {mu}m radiation according to the Beer-Lambert law. The heating of the interaction area gives rise to thermal or thermo-mechanical damages. PMMA is damaged following a boiling process. Stretched PMMA is fractured first, releasing stresses, then boiled like moulded PMMA at higher energy. BK7 crazed after the irradiation due to thermomechanical stresses, silicate melt and vaporized. Optical damages have been characterized by measuring the contrast transfer function through the irradiated samples.

  13. Health care law versus constitutional law.

    PubMed

    Hall, Mark A

    2013-04-01

    National Federation of Independent Business v. Sebelius, the Supreme Court's ruling on the Patient Protection and Affordable Care Act, is a landmark decision - both for constitutional law and for health care law and policy. Others will study its implications for constitutional limits on a range of federal powers beyond health care. This article considers to what extent the decision is also about health care law, properly conceived. Under one view, health care law is the subdiscipline that inquires how courts and government actors take account of the special features of medicine that make legal or policy issues especially problematic - rather than regarding health care delivery and finance more generically, like most any other economic or social enterprise. Viewed this way, the opinions from the Court's conservative justices are mainly about general constitutional law principles. In contrast, Justice Ruth Bader Ginsburg's dissenting opinion for the four more liberal justices is just as much about health care law as it is about constitutional law. Her opinion gives detailed attention to the unique features of health care finance and delivery in order to inform her analysis of constitutional precedents and principles. Thus, the Court's multiple opinions give a vivid depiction of the compelling contrasts between communal versus individualistic conceptions of caring for those in need, and between health care and health insurance as ordinary commodities versus ones that merit special economic, social, and legal status. PMID:23262771

  14. Damage and fatigue described by a fractional derivative model

    NASA Astrophysics Data System (ADS)

    Caputo, Michele; Fabrizio, Mauro

    2015-07-01

    As in [1], damage is associated with fatigue that a material undergoes. In this paper, because we work with viscoelastic solids represented by a fractional model, damage is described by the order of the fractional derivative, which represents the phase field satisfying Ginzburg-Landau equation, which describes the evolution of damage. Finally, in our model, damage is caused, not only by fatigue, but also directly by a source related to environmental factors and described by a positive time function.

  15. Law of Empires.

    ERIC Educational Resources Information Center

    Martz, Carlton

    2001-01-01

    This issue of "Bill of Rights in Action" explores issues raised by empires and imperial law. The first article, "Clash of Empires: The Fight for North America," looks at the clash of empires and the fight for North America during the 18th century. The second article, "When Roman Law Ruled the Western World," examines Roman Law, which helped hold…

  16. The Laws Are Yours.

    ERIC Educational Resources Information Center

    Lawyers' Wives of Wisconsin, Racine.

    The pamphlet briefly describes various facets of the law and legal system in Wisconsin, and defines many legal terms. The objective is to further public understanding of the law and of the legal profession, particularly in Wisconsin. No attempt is made to answer specific legal questions. Sections cover civil and criminal law; the federal court…

  17. Henry's Law: A Retrospective

    ERIC Educational Resources Information Center

    Rosenberg, Robert M.; Peticolas, Warner L.

    2004-01-01

    A retrospective view of Henry's law and its applicability in any specific system at a finite concentration is tested. It can be concluded that Henry's law is only a limiting law and is adequate at low mole fractions but is useful for practical purposes where high precision is not required.

  18. School of Law

    ERIC Educational Resources Information Center

    Olsen, Ken

    2005-01-01

    This article explains how Street Law helps teachers to defuse tensions between students and police through a combination of education, empathy, and expertise. Street Law was born at Georgetown in 1972. Every year, it sends two dozen law students like Courtney Donovan into Washington, D.C., high schools to help teach the year long course. Street

  19. Peridynamic modeling of pitting corrosion damage

    NASA Astrophysics Data System (ADS)

    Chen, Ziguang; Bobaru, Florin

    2015-05-01

    In this paper we introduce a peridynamic model for the evolution of damage from pitting corrosion capable of capturing subsurface damage. We model the anodic reaction in corrosion processes (in which electroplating is negligible) as an effective peridynamic diffusion process in the electrolyte/solid system coupled with a phase-change mechanism that allows for autonomous evolution of the moving interface. In order to simulate creation of subsurface damage, we introduce a corrosion damage model based on a stochastic relationship that connects the concentration in the metal to the damage of peridynamic mechanical-bonds that are superposed onto diffusion-bonds. We study convergence of this formulation for diffusion-dominated stage. The model leads to formation of a subsurface damage layer, seen in experiments. We validate results against experiments on pit growth rate and polarization data for pitting corrosion. We extend the 1D model to the 2D and 3D, and introduce a new damage-dependent corrosion model to account for broken mechanical bonds that enhance the corrosion rate. This coupled model can predict the pit shape and damage profile in materials with microstructural heterogeneities, such as defects, interfaces, inclusions, and grain boundaries.

  20. Omori law for eruption foreshocks and aftershocks

    NASA Astrophysics Data System (ADS)

    Schmid, A.; Grasso, J.-R.

    2012-07-01

    Using the 1973-2009 worldwide catalogs for M ≥ 4.8 seismicity and VEI ≥ 0 volcano eruptions, we compare the properties of seismic damage patterns contemporary with eruption with the properties of foreshocks and aftershocks of classic tectonic earthquakes. Using superposed epoch analysis, we demonstrated that the seismicity rate after eruption decreases as a power law similar to the Omori law of earthquake aftershocks. We further show that a complete mapping of Omori law of earthquake aftershocks onto eruption aftershocks does exist as Rerup(t) = (K0.10β(VEI))/[(t+c)p], volcanic explosivity index (VEI), being an empirical measure that exponentially scales with eruption size. β close to 0.4 is the value reported for M = 5-6.5 earthquakes from the same catalog. The p values are in the 0.7 range, i.e., robustly smaller than the 0.9-1.0 range for earthquake aftershocks we estimated in the volcanic area. K value for eruptions is 2-10 times smaller than for earthquakes, and it scales with VEI values. All those parameters characterize a slower damage relaxation after eruptions than after earthquakes. When earthquakes' foreshock rates are proposed to be independent of the main shock magnitude, we resolved a strong increase in foreshock rates including an increase of the p' value of the inverse Omori law prior eruptions with eruption size. These patterns, all emerging from mean field analysis, are evidence of the volcanic eruptions being contemporary with a stochastic brittle damage in the Earth crust. These results suggest a generic damage relaxation within the Earth crust as power law distributed after or before events. The loading and relaxation exponents and the damage rate emerge as being controlled by the loading rate, as reported during lab-scale experiments. The more impulsive the loading, i.e., km/s for the slip velocity during earthquakes against km/h for dyke propagation, the faster the relaxation (0.9-1.0 p values for earthquakes' aftershocks against 0.7 for eruptions' aftershocks). Before eruptions, the larger the impending events, the higher the p values. All the observations converge toward the amplitude and frequency of the stress step to drive the Omori law parameters as qualitatively reproduced by the rate and state friction law response of brittle crust faults to loading.

  1. Is life law-like?

    PubMed

    Weiss, Kenneth M; Buchanan, Anne V

    2011-08-01

    Genes are generally assumed to be primary biological causes of biological phenotypes and their evolution. In just over a century, a research agenda that has built on Mendel's experiments and on Darwin's theory of natural selection as a law of nature has had unprecedented scientific success in isolating and characterizing many aspects of genetic causation. We revel in these successes, and yet the story is not quite so simple. The complex cooperative nature of genetic architecture and its evolution include teasingly tractable components, but much remains elusive. The proliferation of data generated in our "omics" age raises the question of whether we even have (or need) a unified theory or "law" of life, or even clear standards of inference by which to answer the question. If not, this not only has implications for the widely promulgated belief that we will soon be able to predict phenotypes like disease risk from genes, but also speaks to the limitations in the underlying science itself. Much of life seems to be characterized by ad hoc, ephemeral, contextual probabilism without proper underlying distributions. To the extent that this is true, causal effects are not asymptotically predictable, and new ways of understanding life may be required. PMID:21828277

  2. Macrothermodynamics of Biological Evolution:

    NASA Astrophysics Data System (ADS)

    Gladyshev, Georgi P.

    The author sets forth general considerations pertaining to the thermodynamic theory of biological evolution and the aging of living organisms. It becomes much easier to comprehend the phenomenon of life scrutinizing the formation of structural hierarchies of biological matter applying different temporal scales. These scales are 'identified' by nature itself, and this is reflected in the law of temporal hierarchies. The author discusses some misunderstandings in thermodynamics and evolutionary biology. A simple physicochemical model of biological evolution and the development of living beings is proposed. The considered theory makes it possible to use physicochemical evaluations to develop effective anti-aging diets.

  3. Three Laws in Darwinian Evolutionary Theory

    NASA Astrophysics Data System (ADS)

    Ao, Ping

    2006-03-01

    Recent works to formulate laws in Darwinian evolutionary dynamics will be discussed. Specifically, three laws which form a consistent mathematical framework for the evolutionary dynamics in biology will be spelt out. The second law is most quantitative and is explicitly expressed in the unique form of a stochastic differential equation. Salient features of Darwinian evolutionary dynamics are captured by this law: the probabilistic nature of evolution, ascendancy, and the adaptive landscape. Four dynamical elements are introduced in this formulation: the ascendant matrix, the transverse matrix, the Wright evolutionary potential, and the stochastic drive. The first law may be regarded as a special case of the second law. It gives the reference point to discuss the evolutionary dynamics. The third law describes the relationship between the focused level of description to its lower and higher ones, and defines the dichotomy of deterministic and stochastic drives. It is an acknowledgement of the hierarchical structure in biology. A new interpretation of Fisher's fundamental theorem of natural selection is provided in terms of the F-Theorem. Ref. P. Ao, Physics of Life Reviews 2 (2005) 117-156.

  4. Intermediate evolution using SNIa, and BAO

    NASA Astrophysics Data System (ADS)

    Cárdenas, Víctor H.; Herrera, O.

    2015-10-01

    We study the intermediate evolution model and show that, compared with the recent study of a power-law evolution, the intermediate evolution is a better description of the low-redshift regime supported by observations from type Ia supernovae and BAO. We found also that recent data suggest that the intermediate evolution is as good a fit to this redshift range as the \\varLambdaCDM model.

  5. A two-scale damage model with material length

    NASA Astrophysics Data System (ADS)

    Dascalu, Cristian

    2009-09-01

    The Note presents the formulation of a class of two-scale damage models involving a micro-structural length. A homogenization method based on asymptotic developments is employed to deduce the macroscopic damage equations. The damage model completely results from energy-based micro-crack propagation laws, without supplementary phenomenological assumptions. We show that the resulting two-scale model has the property of capturing micro-structural lengths. When damage evolves, the micro-structural length is given by the ratio of the surface density of energy dissipated during the micro-crack growth and the macroscopic damage energy release rate per unit volume of the material. The use of fracture criteria based on resistance curves or power laws for sub-critical growth of micro-cracks leads to quasi-brittle and, respectively, time-dependent damage models. To cite this article: C. Dascalu, C. R. Mecanique 337 (2009).

  6. The evolution of airplanes

    NASA Astrophysics Data System (ADS)

    Bejan, A.; Charles, J. D.; Lorente, S.

    2014-07-01

    The prevailing view is that we cannot witness biological evolution because it occurred on a time scale immensely greater than our lifetime. Here, we show that we can witness evolution in our lifetime by watching the evolution of the flying human-and-machine species: the airplane. We document this evolution, and we also predict it based on a physics principle: the constructal law. We show that the airplanes must obey theoretical allometric rules that unite them with the birds and other animals. For example, the larger airplanes are faster, more efficient as vehicles, and have greater range. The engine mass is proportional to the body size: this scaling is analogous to animal design, where the mass of the motive organs (muscle, heart, lung) is proportional to the body size. Large or small, airplanes exhibit a proportionality between wing span and fuselage length, and between fuel load and body size. The animal-design counterparts of these features are evident. The view that emerges is that the evolution phenomenon is broader than biological evolution. The evolution of technology, river basins, and animal design is one phenomenon, and it belongs in physics.

  7. Darwinian Evolution and Fractals

    NASA Astrophysics Data System (ADS)

    Carr, Paul H.

    2009-05-01

    Did nature's beauty emerge by chance or was it intelligently designed? Richard Dawkins asserts that evolution is blind aimless chance. Michael Behe believes, on the contrary, that the first cell was intelligently designed. The scientific evidence is that nature's creativity arises from the interplay between chance AND design (laws). Darwin's ``Origin of the Species,'' published 150 years ago in 1859, characterized evolution as the interplay between variations (symbolized by dice) and the natural selection law (design). This is evident in recent discoveries in DNA, Madelbrot's Fractal Geometry of Nature, and the success of the genetic design algorithm. Algorithms for generating fractals have the same interplay between randomness and law as evolution. Fractal statistics, which are not completely random, characterize such phenomena such as fluctuations in the stock market, the Nile River, rainfall, and tree rings. As chaos theorist Joseph Ford put it: God plays dice, but the dice are loaded. Thus Darwin, in discovering the evolutionary interplay between variations and natural selection, was throwing God's dice!

  8. Time-dependent corona models - Scaling laws

    NASA Technical Reports Server (NTRS)

    Korevaar, P.; Martens, P. C. H.

    1989-01-01

    Scaling laws are derived for the one-dimensional time-dependent Euler equations that describe the evolution of a spherically symmetric stellar atmosphere. With these scaling laws the results of the time-dependent calculations by Korevaar (1989) obtained for one star are applicable over the whole Hertzsprung-Russell diagram and even to elliptic galaxies. The scaling is exact for stars with the same M/R-ratio and a good approximation for stars with a different M/R-ratio. The global relaxation oscillation found by Korevaar (1989) is scaled to main sequence stars, a solar coronal hole, cool giants and elliptic galaxies.

  9. Power-law distributions in protoneutron stars

    NASA Astrophysics Data System (ADS)

    Gervino, G.; Lavagno, A.; Pigato, D.

    2016-01-01

    We investigate the physical properties of the protoneutron stars in the framework of a relativistic mean-field theory based on nonextensive statistical mechanics, characterized by power-law distributions. We study the finite-temperature equation of state in, β-stable matter at fixed entropy per baryon, in the absence and in the presence of hyperons and trapped neutrinos. We show that nonextensive power-law effects could play a crucial role in the structure and in the evolution of the protoneutron stars also for small deviations from the standard Boltzmann-Gibbs statistics.

  10. Conservation law of operator current in open quantum systems

    NASA Astrophysics Data System (ADS)

    Salmilehto, J.; Solinas, P.; Möttönen, M.

    2012-03-01

    We derive a fundamental conservation law of operator current for master equations describing reduced quantum systems. If this law is broken, the temporal integral of the current operator of an arbitrary system observable does not yield in general the change of that observable in the evolution. We study Lindblad-type master equations as examples and prove that the application of the secular approximation during their derivation results in a violation of the conservation law. We show that generally any violation of the law leads to artificial corrections to the complete quantum dynamics, thus questioning the accuracy of the particular master equation.

  11. Damage analysis and fundamental studies. Quarterly progress report, October-December 1979

    SciTech Connect

    Doran, D. G.

    1980-02-01

    Progress on each of the following topics is outlined: (1) rotating target neutron source, (2) fusion materials irradiation test facility, (3) environmental characterization, (4) damage production, and (5) damage microstructure evolution and mechanical behavior. (MOW)

  12. Zipf's law, power laws and maximum entropy

    NASA Astrophysics Data System (ADS)

    Visser, Matt

    2013-04-01

    Zipf's law, and power laws in general, have attracted and continue to attract considerable attention in a wide variety of disciplines—from astronomy to demographics to software structure to economics to linguistics to zoology, and even warfare. A recent model of random group formation (RGF) attempts a general explanation of such phenomena based on Jaynes' notion of maximum entropy applied to a particular choice of cost function. In the present paper I argue that the specific cost function used in the RGF model is in fact unnecessarily complicated, and that power laws can be obtained in a much simpler way by applying maximum entropy ideas directly to the Shannon entropy subject only to a single constraint: that the average of the logarithm of the observable quantity is specified.

  13. Brittle creep, damage, and time to failure in rocks

    NASA Astrophysics Data System (ADS)

    Amitrano, David; Helmstetter, AgnèS.

    2006-11-01

    We propose a numerical model based on static fatigue laws in order to model the time-dependent damage and deformation of rocks under creep. An empirical relation between time to failure and applied stress is used to simulate the behavior of each element of our finite element model. We review available data on creep experiments in order to study how the material properties and the loading conditions control the failure time. The main parameter that controls the failure time is the applied stress. Two commonly used models, an exponential tf-exp (-bσ/σ0) and a power law function tf-σb' fit the data as well. These time-to-failure laws are used at the scale of each element to simulate its damage as a function of its stress history. An element is damaged by decreasing its Young's modulus to simulate the effect of increasing crack density at smaller scales. Elastic interactions between elements and heterogeneity of the mechanical properties lead to the emergence of a complex macroscopic behavior, which is richer than the elementary one. In particular, we observe primary and tertiary creep regimes associated respectively with a power law decay and increase of the rate of strain, damage event and energy release. Our model produces a power law distribution of damage event sizes, with an average size that increases with time as a power law until macroscopic failure. Damage localization emerges at the transition between primary and tertiary creep, when damage rate starts accelerating. The final state of the simulation shows highly damaged bands, similar to shear bands observed in laboratory experiments. The thickness and the orientation of these bands depend on the applied stress. This model thus reproduces many properties of rock creep, which were previously not modeled simultaneously.

  14. Grain evolution during hot forging

    NASA Astrophysics Data System (ADS)

    Jin, Quanlin

    2013-05-01

    A review on grain evolution during hot forging is presented in this paper. The discussion focus is on the experimental law, the microscopic mechanism, the physical model and the evolution equations of grain refinement and growth. This is because the grain evolution is the most important microstructure evolution effecting on the part mechanical behaviors, and to establish reasonable grain evolution is a very important and difficult work for macro microscopic coupling constitutive equation. The following contents about constitutive equation and grain evolution are discussed. 1) The experimental phenomena and evolution laws of grain growth and grain refinement under differential working conditions (deformation, heating, cooling) in order to adapt to the needs of numerical simulation of whole forging process. 2) The advantages and disadvantages of the traditional empirical equations on grain growth, grain refinement and recrystallization process are analyzed. 3) The recent advances in physic models for dynamic recrystallizaton and dynamic grain growth are introduced in detail. Comparing to the empirical equations, these models are closer to the actual physical process. The models not only describe the details of grain changes, but also reveal the relationship between the accumulated dislocations energy and grain size evolution. In addition, the assumptions used in the models and their influences on prediction function are also discussed in order to improve the models.

  15. Power-law relaxation in a complex system: Omori law after a financial market crash.

    PubMed

    Lillo, F; Mantegna, R N

    2003-07-01

    We study the relaxation dynamics of a financial market just after the occurrence of a crash by investigating the number of times the absolute value of an index return is exceeding a given threshold value. We show that the empirical observation of a power law evolution of the number of events exceeding the selected threshold (a behavior known as the Omori law in geophysics) is consistent with the simultaneous occurrence of (i) a return probability density function characterized by a power law asymptotic behavior and (ii) a power-law relaxation decay of its typical scale. Our empirical observation cannot be explained within the framework of simple and widespread stochastic volatility models. PMID:12935212

  16. Adhesive Characterization and Progressive Damage Analysis of Bonded Composite Joints

    NASA Technical Reports Server (NTRS)

    Girolamo, Donato; Davila, Carlos G.; Leone, Frank A.; Lin, Shih-Yung

    2014-01-01

    The results of an experimental/numerical campaign aimed to develop progressive damage analysis (PDA) tools for predicting the strength of a composite bonded joint under tensile loads are presented. The PDA is based on continuum damage mechanics (CDM) to account for intralaminar damage, and cohesive laws to account for interlaminar and adhesive damage. The adhesive response is characterized using standard fracture specimens and digital image correlation (DIC). The displacement fields measured by DIC are used to calculate the J-integrals, from which the associated cohesive laws of the structural adhesive can be derived. A finite element model of a sandwich conventional splice joint (CSJ) under tensile loads was developed. The simulations indicate that the model is capable of predicting the interactions of damage modes that lead to the failure of the joint.

  17. [Law 6/84: "an inappropriate law"].

    PubMed

    Barroco, L E

    1994-01-01

    The intervention of Dr. Luis Elmano Barroco was evaluated at a meeting on March 19, 1994, on the topic of the state of abortion after 10 years of the new abortion law. Some aspects of the law of 1984 are characterized as inappropriate and inadequate because of the experience of the maternity ward of Dr. Alfredo da Costa. It was expected that in the wake of the publication of the law, official health care institutions would provide services for termination of pregnancy in accordance with legal indications. However, a survey carried out by the Association for Family Planning in July 1993 revealed that more than 50% of hospitals did not perform abortions because of the inexistence of specialized services or lack of resources or on grounds of conscientious objection. Even a revision of the abortion law does not take into consideration the fact that before 12 weeks of gestation it is difficult to precisely confirm grave lesions or the physical and psychological state of health of the pregnant woman which could be potentially life threatening. It was not taken into account either that it is impossible to diagnose definitively chromosomal aberrations, severe diseases, and fetal malformation before the 16th week. The law did not contemplate the prevailing socioeconomical conditions either that lead to clandestine abortion with high morbidity and mortality from cervical lesions, uterine perforation, infections, sepsis, and salpingitis. Prenatal diagnosis for eugenic abortion can be carried out by cytogenetic analysis of the amniotic fluid and ecography, but such diagnosis probably amounts to only 30-40% of risk cases in the whole country. A recent study by the Johns Hopkins University indicated that the chance of survival of a child born before 24 weeks is nil, therefore the limit of induced abortion should be extended to the 24th week to facilitate diagnosis of possible genetic abnormalities. PMID:12179270

  18. School Law Update, 1986.

    ERIC Educational Resources Information Center

    Jones, Thomas N., Ed.; Semler, Darel P., Ed.

    A wide variety of contemporary legal issues, involving all levels of public and private education, are addressed in the 20 separate chapters comprising this volume. The titles and authors of the chapters are as follows: (1) Due Process of Law: Loudermill v. Cleveland Board of Education (Hooker); (2) Schools, Technology and the Law (Helm); (3)…

  19. Teaching Information Technology Law

    ERIC Educational Resources Information Center

    Taylor, M. J.; Jones, R. P.; Haggerty, J.; Gresty, D.

    2009-01-01

    In this paper we discuss an approach to the teaching of information technology law to higher education computing students that attempts to prepare them for professional computing practice. As information technology has become ubiquitous its interactions with the law have become more numerous. Information technology practitioners, and in particular

  20. Pop Goes the Law

    ERIC Educational Resources Information Center

    Harper, Steven J.

    2013-01-01

    The Law School Admission Council recently reported that applications were heading toward a 30-year low, reflecting, as a "New York Times" article put it, "increased concern over soaring tuition, crushing student debt, and diminishing prospects of lucrative employment upon graduation." Since 2004 the number of law-school applicants has dropped from…

  1. Science and the Law.

    ERIC Educational Resources Information Center

    Kennedy, Donald; Merrill, Richard A.

    2000-01-01

    Explaines the role of the Carnegie Commission which was formed to explore the relationship between the disciplines of science, technology, and the law. Discusses concerns about the individual right of privacy in projects such as the Human Genome Project. Focuses on the panel on Science, Technology, and Law which was established in 1999. (YDS)

  2. The Law of Elasticity

    ERIC Educational Resources Information Center

    Cocco, Alberto; Masin, Sergio Cesare

    2010-01-01

    Participants estimated the imagined elongation of a spring while they were imagining that a load was stretching the spring. This elongation turned out to be a multiplicative function of spring length and load weight--a cognitive law analogous to Hooke's law of elasticity. Participants also estimated the total imagined elongation of springs joined…

  3. Nanotechnology and the Law

    NASA Astrophysics Data System (ADS)

    Desmoulin-Canselier, Sonia; Lacour, Stéphanie

    Law and nanotechnology form a vast subject. The aim here will be to examine them from the societal standpoint of nanoethics, if necessary without due reference to the work that has been undertaken. For while law differs from ethics, as we shall attempt to explain throughout this reflection, it must also be studied in its relationship with social realities.

  4. Law Studies Curriculum.

    ERIC Educational Resources Information Center

    Seminole County Board of Public Instruction, Sanford, FL. Dept. of Curriculum Services.

    This law studies curriculum guide describes a course designed to provide secondary students with the opportunity to acquire an understanding of the U.S. legal process. The law studies course is intended to develop corresponding concepts and skills in conjunction with the content presented. The content areas of the curriculum include: (1)…

  5. Civil Law: 12 Activities.

    ERIC Educational Resources Information Center

    Dresbach, Debra

    These learning activities on civil law are intended to supplement the secondary level Scholastic materials "Living Law." Case studies, simulations, and role-play activities are included. Information provided for each activity includes a brief overview, background information, teacher instructions and a description of each activity. Activities…

  6. The Corporate Law Curriculum

    ERIC Educational Resources Information Center

    Mofsky, James S.

    1976-01-01

    On the premise that corporate counsel must be an able diagnostician before he can focus on highly specialized and interrelated issues of business law, the author suggests an approach to corporate law curriculum in which the basic course balances the quality and quantity of material designed to create the needed sensitivity. (JT)

  7. Lotka's Law Revisited.

    ERIC Educational Resources Information Center

    Potter, William Gray

    1981-01-01

    Discusses the literature that has become associated with Lotka's Law of Scientific Productivity (a general theoretical estimate of author productivity in the sciences) and attempts to identify the important factors of Lotka's original methodology that should be considered when attempting to test applicability of Lotka's Law. Forty-seven references…

  8. Social Studies: Law Education.

    ERIC Educational Resources Information Center

    Curriculum Review, 1979

    1979-01-01

    Reviews 11 series, texts, supplements, kits, and professional references for law instruction, including civil and criminal law, the Bill of Rights, and controversial legal issues: arson, gun control, capital punishment, and euthanasia. While all grade levels are covered, the emphasis is on secondary-level materials. (SJL)

  9. Teaching Information Technology Law

    ERIC Educational Resources Information Center

    Taylor, M. J.; Jones, R. P.; Haggerty, J.; Gresty, D.

    2009-01-01

    In this paper we discuss an approach to the teaching of information technology law to higher education computing students that attempts to prepare them for professional computing practice. As information technology has become ubiquitous its interactions with the law have become more numerous. Information technology practitioners, and in particular…

  10. Teachers and the Law.

    ERIC Educational Resources Information Center

    Fischer, Louis; And Others

    This book is designed to promote legal literacy for public school teachers. It examines a wide range of constitutional, statutory, and case law that directly affects their work. Its purpose is to provide teachers with the knowledge necessary to comply with the law, assert their rights, and bring violations to the attention of administrators and…

  11. Charles' Law of Gases.

    ERIC Educational Resources Information Center

    Petty, John T.

    1995-01-01

    Describes an experiment that uses air to test Charles' law. Reinforces the student's intuitive feel for Charles' law with quantitative numbers they can see, introduces the idea of extrapolating experimental data to obtain a theoretical value, and gives a physical quantitative meaning to the concept of absolute zero. (JRH)

  12. Bicycle Law Enforcement Manual.

    ERIC Educational Resources Information Center

    Hunter, William W.; Stutts, Jane C.

    This manual is an attempt to draw together relevant resources and information for localities interested in developing a bicycle law enforcement operation. It is divided into five major sections. Section I explains the need for and importance of bicycle law enforcement. In section II are presented examples of past and current bicycle law…

  13. Law and You.

    ERIC Educational Resources Information Center

    Schurr, Sandra

    Fourteen activity units are presented to help elementary and junior high students learn about laws, rules, and respect for others. A pretest introduces the materials by asking students why society has rules and laws, which ones apply to children, and what reactions students have to the word "cop." The subsequent units involve the students in group…

  14. Researching International Law.

    ERIC Educational Resources Information Center

    Kennedy, Ann

    Designed for the undergraduate student who is doing research on public international law and graduate students in fields other than law, this guide is specifically addressed to students at San Francisco State University, although the resources discussed are typical of those to be found in a medium-sized academic library. The guide is divided into

  15. Laws for Young Mountaineers.

    ERIC Educational Resources Information Center

    Kanawha County Board of Education, Charleston, WV.

    This booklet introduces secondary grade students to the criminal laws of West Virginia. It can easily be adapted and used by educators in other states. The authors believe that young people must recognize and understand these laws and the mechanisms which society uses to implement and enforce them if they are to function as an integral, important,…

  16. Reinventing Howard's Law School.

    ERIC Educational Resources Information Center

    Glenn, Gwendolyn

    2001-01-01

    Describes efforts by Alice Gresham Bullock, dean of the Howard University School of Law, to improve the school (including building a new library and improving relations with faculty) and restore Howard to its previous stature as a leader in civil rights law. (EV)

  17. Indian Law Enforcement History.

    ERIC Educational Resources Information Center

    Etheridge, David

    Written as a tribute to American Indian law enforcement officers and the Indian Criminal Justice System, this monographh details the history of the legislative, judicial, financial, and cultural problems associated with the development of Indian law enforcement. Citing numerous court cases, pieces of legislation, and individual and organizational…

  18. Language and the Law.

    ERIC Educational Resources Information Center

    Gibbons, John

    1999-01-01

    Discusses the language of law and its general interest to the field of applied linguistics. Specific focus is on legal language, the problems and remedies of legal communication (e.g., language and disadvantage before the law, improving legal communication) the legislation of language (e.g., language rights, language crimes), and forensic…

  19. EOS Laser Atmosphere Wind Sounder (LAWS) investigation

    NASA Technical Reports Server (NTRS)

    1996-01-01

    In this final report, the set of tasks that evolved from the Laser Atmosphere Wind Sounder (LAWS) Science Team are reviewed, the major accomplishments are summarized, and a complete set of resulting references provided. The tasks included preparation of a plan for the LAWS Algorithm Development and Evolution Laboratory (LADEL); participation in the preparation of a joint CNES/NASA proposal to build a space-based DWL; involvement in the Global Backscatter Experiments (GLOBE); evaluation of several DWL concepts including 'Quick-LAWS', SPNDL and several direct detection technologies; and an extensive series of system trade studies and Observing System Simulation Experiments (OSSE's). In this report, some of the key accomplishments are briefly summarized with reference to interim reports, special reports, conference/workshop presentations, and publications.

  20. International resources law

    SciTech Connect

    Not Available

    1991-01-01

    This book covers: Historical origins of civil code legal systems; Modern civil law practice for mineral lawyers; Treaties and agreements for protection of international investments; Europe 1992-toward a single energy market; Dispute resolution in international agreements; Assessment of political risk; Reducing political risk; Protecting mineral investments from upheaval in developing countries; Typical world petroleum arrangements; government take in the Pacific Rim - Papua New Guinea; Mineral base of the USSR and prospects of investment; International taxation for the mining practitioner; Tax considerations - branch versus subsidiary; Doing business in the host country - nontax considerations; Impact of host-country laws on operations and profits; Mineral development and native rights - New Zealand; Designing the investment vehicle: mining; International oil and gas joint ventures; Selected U.S. laws with extraterritorial effect; U.S. tax and securities laws applied to foreign joint venturers; and Extraterritorial effect of U.S. laws.

  1. Impact crater scaling laws

    NASA Technical Reports Server (NTRS)

    Holsapple, K. A.

    1987-01-01

    Impact craters are numerous on planetary bodies and furnish important information about the composition and past histories of those bodies. The interpretation of that information requires knowledge about the fundamental aspects of impact cratering mechanics. Since the typical conditions of impacts are at a size scale and velocity far in excess of experimental capabilities, direct simulations are precluded. Therefore, one must rely on extrapolation from experiments of relatively slow impacts of very small bodies, using physically based scaling laws, or must study the actual cases of interest using numerical code solutions of the fundamental physical laws that govern these processes. A progress report is presented on research on impact cratering scaling laws, on numerical studies that were designed to investigate those laws, and on various applications of the scaling laws developed by the author and his colleagues. These applications are briefly reviewed.

  2. Accepting Evolution or Discarding Science

    ERIC Educational Resources Information Center

    Sharpes, Donald K.; Peramas, Mary M.

    2006-01-01

    Challenging basic principles of constitutional law, advocates of intelligent design are undermining educators' ability to teach evolution in their science classrooms. Because US Supreme Court rulings now prohibit creationist accounts of the origin of life in schools, arguments favoring divine intervention, known as intelligent design, have emerged…

  3. Plate tectonics, damage and inheritance.

    PubMed

    Bercovici, David; Ricard, Yanick

    2014-04-24

    The initiation of plate tectonics on Earth is a critical event in our planet's history. The time lag between the first proto-subduction (about 4 billion years ago) and global tectonics (approximately 3 billion years ago) suggests that plates and plate boundaries became widespread over a period of 1 billion years. The reason for this time lag is unknown but fundamental to understanding the origin of plate tectonics. Here we suggest that when sufficient lithospheric damage (which promotes shear localization and long-lived weak zones) combines with transient mantle flow and migrating proto-subduction, it leads to the accumulation of weak plate boundaries and eventually to fully formed tectonic plates driven by subduction alone. We simulate this process using a grain evolution and damage mechanism with a composite rheology (which is compatible with field and laboratory observations of polycrystalline rocks), coupled to an idealized model of pressure-driven lithospheric flow in which a low-pressure zone is equivalent to the suction of convective downwellings. In the simplest case, for Earth-like conditions, a few successive rotations of the driving pressure field yield relic damaged weak zones that are inherited by the lithospheric flow to form a nearly perfect plate, with passive spreading and strike-slip margins that persist and localize further, even though flow is driven only by subduction. But for hotter surface conditions, such as those on Venus, accumulation and inheritance of damage is negligible; hence only subduction zones survive and plate tectonics does not spread, which corresponds to observations. After plates have developed, continued changes in driving forces, combined with inherited damage and weak zones, promote increased tectonic complexity, such as oblique subduction, strike-slip boundaries that are subparallel to plate motion, and spalling of minor plates. PMID:24717430

  4. Child Labor Laws in Mississippi.

    ERIC Educational Resources Information Center

    Robbins, Jerry H.

    Child labor laws have not attracted much attention in recent years. Much of the basic legislation and the case law dates from the early part of the 20th century. This paper discusses the Mississippi statutory law on the subject, compares that law with legislation in five other States, and discusses case law in Mississippi and in other States.…

  5. Chemical Laws, Idealization and Approximation

    ERIC Educational Resources Information Center

    Tobin, Emma

    2013-01-01

    This paper examines the notion of laws in chemistry. Vihalemm ("Found Chem" 5(1):7-22, 2003) argues that the laws of chemistry are fundamentally the same as the laws of physics they are all "ceteris paribus" laws which are true "in ideal conditions". In contrast, Scerri (2000) contends that the laws of chemistry are…

  6. [Teaching about Law and Literature].

    ERIC Educational Resources Information Center

    Ryan, John Paul, Ed.

    1993-01-01

    This issue of "Focus on Law Studies" contains a special emphasis on teaching about law and literature, in the form of the following six articles: "Law and Literature: New Combinations in Teaching" (John Paul Ryan); "Teaching Law and American Literature" (Janet Eldred); "Teaching Law with Sacco, Vanzetti, and the Rosenbergs" (Susan N. Herman); Ann…

  7. Chemical Laws, Idealization and Approximation

    ERIC Educational Resources Information Center

    Tobin, Emma

    2013-01-01

    This paper examines the notion of laws in chemistry. Vihalemm ("Found Chem" 5(1):7-22, 2003) argues that the laws of chemistry are fundamentally the same as the laws of physics they are all "ceteris paribus" laws which are true "in ideal conditions". In contrast, Scerri (2000) contends that the laws of chemistry are

  8. Substitution of Azotobacter vinelandii hydrogenase small-subunit cysteines by serines can create insensitivity to inhibition by O2 and preferentially damages H2 oxidation over H2 evolution.

    PubMed Central

    McTavish, H; Sayavedra-Soto, L A; Arp, D J

    1995-01-01

    Mutants in which conserved cysteines 294, 297 or 64 and 65 of the Azotobacter vinelandii hydrogenase small subunit were replaced by serines were studied. Cysteines 294 and 297 are homologous to cysteines 246 and 249 of the Desulfovibrio gigas hydrogenase, and these cysteines are ligands to the [3Fe-4S] clusters (A. Volbeda, M.-H. Charon, C. Piras, E. C. Hatchikian, M. Frey, and J. C. Fontecilla-Camps, Nature (London) 373:580-587, 1995). Cysteine 65 is homologous to cysteine 20 of the D. gigas hydrogenase, and this cysteine is a ligand to the proximal [4Fe-4S] cluster. All three mutants retained some hydrogenase activity. All three mutants studied had H2 oxidation-to-H2 evolution activity ratios with whole cells of approximately 1.5, compared with 46 for the wild type. The changes preferentially deplete H2 oxidation activity, while having less effect on evolution. The K64,65C-->S hydrogenase was partially purified and had a specific activity for the evolution reaction that was 22% that of the wild type, while the oxidation-specific activity was 2% that of the wild type. Because cysteine 65 provides a ligand to the proximal [4Fe-4S] cluster, this cluster can be altered without entirely eliminating enzyme activity. Likewise, the detection of H2 evolution and H2 oxidation activities with whole cells and membranes of the K294C-->S and K297C-->S mutants indicates that the [3Fe-4S] cluster can also be altered or possibly eliminated without entirely eliminating enzyme activity. Membranes with K294C-->S or K297C-->S hydrogenase were uninhibited by O2 in H2 oxidation and uninhibited by H2 in H2 evolution. Wild-type membranes and membranes with K64,65C-->S hydrogenase were both sensitive to these inhibitors. These data indicate that the [3Fe-4S] cluster controls the reversible inhibition of hydrogenase activity by O2 or H2. PMID:7608067

  9. Acid mine drainage: Common law, SMCRA, and the Clean Water Act

    SciTech Connect

    Henrich, C.

    1995-12-31

    Acid mine drainage is a major problem related to coal mining which, if unabated, can severely damage the aquatic environment. Damage resulting from acid mine drainage was first addressed by common law and riparian principles. As societal laws changed, common law principles alone could not effectively control this problem. Preventing and controlling pollution including acid mine drainage are important goals of the Surface Mining Control Reclamation Act (SMCRA) and the Clean Water Act (CWA). This article examines how common law, SMCRA, and the CWA address the acid mine drainage issue independently, and how improvements in the control of acid mine drainage can be achieved.

  10. The new energy law

    SciTech Connect

    Allen, Z.

    1997-05-01

    Foreign companies, as well as Polish companies, have long awaited the introduction of a new environment for doing business in Poland`s energy sector. The adoption by the Sejm (lower house of the Polish Parliament) of a new Energy Law (Prawo Energetyczne) promises to move Poland into a brave new world for energy sector businesses. With this law, Poland hopes to leapfrog into the vanguard of European countries in terms of privatization and demonopolization of its energy sectors. Only the United Kingdom may be more progressive in this regard. During the past several months, a draft law was passed by the Sejm and sent to the Senate. The Senate introduced nearly 50 changes, passed the law and returned it to the Sejm. At that point, the Sejm committee responsible for this law recommended against almost all the Senate`s changes, returning the draft law to its original form. The actions by the Sejm, now awaited, will be final with only the signature of the president needed to put the law into force. Subsequently, this examination of the law is based upon the draft as originally passed by the Sejm and expected to be signed by Poland`s president. There are several key provisions of the proposed new law that make it so different from the current regulatory structure. The key terms that the Polish government likes to use are privatization and demonopolization, of which the latter is to come first. It is a leap forward from an energy sector that was owned entirely by the State, and where prices at all levels, from the coal mines to the residential consumer, were set without regard to cost.

  11. Lenz's Law Magic Trick

    NASA Astrophysics Data System (ADS)

    Ruiz, Michael J.

    2006-02-01

    The demonstration of Lenz's law by dropping a powerful magnet down a nonmagnetic metal pipe has become a classic lecture-hall demonstration.1,2 An inexpensive version is packaged as a professional magic trick3 called "Newton's Nightmare." Combining sleight-of-hand with a demonstration of Lenz's law is a surefire way to heighten student interest. The subsequent student discussion motivated by a desire to understand the magic trick can lead to a memorable physics lesson. This paper will discuss Lenz's law magic and review literature that reveals the subtlety of the physics.

  12. Sexuality and Australian law.

    PubMed

    Kirby, Michael

    2005-01-01

    The author describes the changing legal environment concerning same-sex relationships in the common law world with special reference to Australia. He refers to shifts in public opinion recorded in opinion polls; important decisions of human rights courts and tribunals; and changes in national law and court decisions. He then reviews the Australian constitutional setting which divides lawmaking responsibility on such subjects between the federal, State and Territory legislatures. He describes initiatives adopted in the States and Territories and the more modest changes effected in federal law and practice. He concludes on a note of optimism concerning Australia's future reforms affecting discrimination on the grounds of sexuality. PMID:15814500

  13. Electrodynamic force law controversy.

    PubMed

    Graneau, P; Graneau, N

    2001-05-01

    Cavalleri et al. [Phys. Rev. E 52, 2505 (1998); Eur. J. Phys. 17, 205 (1996)] have attempted to resolve the electrodynamic force law controversy. This attempt to prove the validity of either the Ampère or Lorentz force law by theory and experiment has revealed only that the two are equivalent when predicting the force on part of a circuit due to the current in the complete circuit. However, in our analysis of internal stresses, only Ampère's force law agrees with experiment. PMID:11415053

  14. Anomalous law of cooling

    SciTech Connect

    Lapas, Luciano C.; Ferreira, Rogelma M. S.; Rubí, J. Miguel; Oliveira, Fernando A.

    2015-03-14

    We analyze the temperature relaxation phenomena of systems in contact with a thermal reservoir that undergoes a non-Markovian diffusion process. From a generalized Langevin equation, we show that the temperature is governed by a law of cooling of the Newton’s law type in which the relaxation time depends on the velocity autocorrelation and is then characterized by the memory function. The analysis of the temperature decay reveals the existence of an anomalous cooling in which the temperature may oscillate. Despite this anomalous behavior, we show that the variation of entropy remains always positive in accordance with the second law of thermodynamics.

  15. Is Life Law-Like?

    PubMed Central

    Weiss, Kenneth M.; Buchanan, Anne V.

    2011-01-01

    Genes are generally assumed to be primary biological causes of biological phenotypes and their evolution. In just over a century, a research agenda that has built on Mendel’s experiments and on Darwin’s theory of natural selection as a law of nature has had unprecedented scientific success in isolating and characterizing many aspects of genetic causation. We revel in these successes, and yet the story is not quite so simple. The complex cooperative nature of genetic architecture and its evolution include teasingly tractable components, but much remains elusive. The proliferation of data generated in our “omics” age raises the question of whether we even have (or need) a unified theory or “law” of life, or even clear standards of inference by which to answer the question. If not, this not only has implications for the widely promulgated belief that we will soon be able to predict phenotypes like disease risk from genes, but also speaks to the limitations in the underlying science itself. Much of life seems to be characterized by ad hoc, ephemeral, contextual probabilism without proper underlying distributions. To the extent that this is true, causal effects are not asymptotically predictable, and new ways of understanding life may be required. PMID:21828277

  16. The LSU Law Center -- Canada Bijuralism Conference. Introduction: Global Law and the Law School Curriculum.

    ERIC Educational Resources Information Center

    Costonis, John J.

    2002-01-01

    Introduces papers from a conference focused on the bijural programs of Louisiana State University Law Center and McGill University Faculty of Law. The programs educate all first-degree law students in both the common law and civil law traditions, preparing them for the increasing globalization of legal practice. (EV)

  17. [Compulsory admission to hospital in Tunisia: a necessary evolution].

    PubMed

    Ellouze, Faten; Lahmar, Aymen; Beji, Rami; Dridi, Anis; Fadhel M'rad, Mohamed

    2015-01-01

    The evolution of the legislation governing compulsory admission to hospital in Tunisia is interesting for two reasons. The country's 2011 revolution notably brought about major changes to the legislative framework, from constitutional through to ordinary laws. At the same time, the current trend for globalisation is also affecting legislation: international laws, treaties and UN charters are imposed on the laws of individual countries. This article looks at how Tunisian law governing compulsory admission to hospital has had to evolve. PMID:26143219

  18. What Is Benford's Law?

    ERIC Educational Resources Information Center

    Bradley, Jonathan R.; Farnsworth, David L.

    2009-01-01

    The surprising property of many data sets that their first significant digits follow Benford's Law provides examples that can pique and hold students' interest. Several ideas for student activities are presented.

  19. Potential conservation laws

    SciTech Connect

    Kunzinger, Michael; Popovych, Roman O.

    2008-10-15

    We prove that potential conservation laws have characteristics depending only on local variables if and only if they are induced by local conservation laws. Therefore, characteristics of pure potential conservation laws have to essentially depend on potential variables. This statement provides a significant generalization of results of the recent paper by Bluman et al. [J. Math. Phys. 47, 113505 (2006)]. Moreover, we present extensions to gauged potential systems, Abelian and general coverings, and general foliated systems of differential equations. An example illustrating possible applications of these results is given. A special version of the Hadamard lemma for fiber bundles and the notions of weighted jet spaces are proposed as new tools for the investigation of potential conservation laws.

  20. Premises for Law

    ERIC Educational Resources Information Center

    Gallagher, Arlene F.

    1975-01-01

    This article presents some of those premises the author believes are significant to the study of law, coupled with some classroom strategies for elementary education designed to examine those premises. (Author/JR)

  1. [The Organ Transplantation Law].

    PubMed

    Yuzawa, Kenji; Takahara, Shiro

    2010-12-01

    The old Organ Transplantation Law was issued in 1997 and had never been revised for 12 years. Brain dead donors had to leave written consent to donate their own organs as well as their family consent. The organ donation from children under 15 years old was prohibited. The majority of the patients in need of organ transplantation died of organ shortages in Japan. Many patients especially children had to travel abroad to receive organs. The amendment bill for the Organ Transplantation Law was passed in the House of Councilors on July 13, 2009. The new Organ Transplantation Law permit organ donation from brain dead donors who had not refused to donate their organs, as long as there is family consent. Children under 15 years old can become donors. This article explains the old and the new Organ Transplantation Laws and the course of the amendment. PMID:21174678

  2. Fault damage zones

    NASA Astrophysics Data System (ADS)

    Kim, Young-Seog; Peacock, David C. P.; Sanderson, David J.

    2004-03-01

    Damage zones show very similar geometries across a wide range of scales and fault types, including strike-slip, normal and thrust faults. We use a geometric classification of damage zones into tip-, wall-, and linking-damage zones, based on their location around faults. These classes can be sub-divided in terms of fault and fracture patterns within the damage zone. A variety of damage zone structures can occur at mode II tips of strike-slip faults, including wing cracks, horsetail fractures, antithetic faults, and synthetic branch faults. Wall damage zones result from the propagation of mode II and mode III fault tips through a rock, or from damage associated with the increase in slip on a fault. Wall damage zone structures include extension fractures, antithetic faults, synthetic faults, and rotated blocks with associated triangular openings. The damage formed at the mode III tips of strike-slip faults (e.g. observed in cliff sections) are classified as wall damage zones, because the damage zone structures are distributed along a fault trace in map view. Mixed-mode tips are likely to show characteristics of both mode II and mode III tips. Linking damage zones are developed at steps between two sub-parallel faults, and the structures developed depend on whether the step is extensional or contractional. Extension fractures and pull-aparts typically develop in extensional steps, whilst solution seams, antithetic faults and synthetic faults commonly develop in contractional steps. Rotated blocks, isolated lenses or strike-slip duplexes may occur in both extensional and contractional steps. Damage zone geometries and structures are strongly controlled by the location around a fault, the slip mode at a fault tip, and by the evolutionary stage of the fault. Although other factors control the nature of damage zones (e.g. lithology, rheology and stress system), the three-dimensional fault geometry and slip mode at each tip must be considered to gain an understanding of damage zones around faults.

  3. Health care litigation: achieving fairness and reasonableness in punitive damages awards.

    PubMed

    Cole, C A; Bernheim, S J; Holtz, M D

    1991-01-01

    This article, the eighth in a series on health care litigation, discusses whether due process considerations require that the common-law procedures for awarding punitive damages be modified and whether juries have undue discretion in awarding punitive damages. The authors analyze an important recent United States Supreme Court punitive damages case and examine the changes states may need to make in their punitive damages assessment procedures to conform with the Supreme Court's holding. PMID:10110710

  4. Rediscovering Kepler's laws using Newton's gravitation law and NASA data

    NASA Astrophysics Data System (ADS)

    Springsteen, Paul; Keith, Jason

    2010-03-01

    Kepler's three laws of planetary motion were originally discovered by using data acquired from Tycho Brache's naked eye observations of the planets. We show how Kepler's third law can be reproduced using planetary data from NASA. We will also be using Newton's Gravitational law to explain why Kepler's three laws exist as they do.

  5. Consequences of Lotka's Law for the Law of Bradford.

    ERIC Educational Resources Information Center

    Egghe, L.

    1985-01-01

    After discussion of the equivalency of the information laws of Bradford, Leimkuhler, Lotka, and Mandelbrot, aberrations from Leimkuhler's law (including "Groos droop" as encountered in practice) are studied. Other aberrations of Leimkuhler's law are explained, starting from generalization of verbal formulation of Bradford's Law. (18 references)…

  6. Damage control resuscitation: history, theory and technique

    PubMed Central

    Ball, Chad G.

    2014-01-01

    Damage control resuscitation (DCR) represents the natural evolution of the initial concept of damage control surgery. It currently includes early blood product transfusion, immediate arrest and/or temporization of ongoing hemorrhage (i.e., temporary intravascular shunts and/or balloon tamponade) as well as restoration of blood volume and physiologic/hematologic stability. As a result, DCR addresses the early coagulopathy of trauma, avoids massive crystalloid resuscitation and leaves the peritoneal cavity open when a patient approaches physiologic exhaustion without improvement. This concept also applies to severe injuries within anatomical transition zones as well as extremities. This review will discuss each of these concepts in detail. PMID:24461267

  7. Damage control resuscitation: history, theory and technique.

    PubMed

    Ball, Chad G

    2014-02-01

    Damage control resuscitation (DCR) represents the natural evolution of the initial concept of damage control surgery. It currently includes early blood product transfusion, immediate arrest and/or temporization of ongoing hemorrhage (i.e., temporary intravascular shunts and/or balloon tamponade) as well as restoration of blood volume and physiologic/hematologic stability. As a result, DCR addresses the early coagulopathy of trauma, avoids massive crystalloid resuscitation and leaves the peritoneal cavity open when a patient approaches physiologic exhaustion without improvement. This concept also applies to severe injuries within anatomical transition zones as well as extremities. This review will discuss each of these concepts in detail. PMID:24461267

  8. The law of the leading digits and the world religions

    NASA Astrophysics Data System (ADS)

    Mir, T. A.

    2012-02-01

    Benford's law states that the occurrence of significant digits in many data sets is not uniform but tends to follow a logarithmic distribution such that the smaller digits appear as first significant digits more frequently than the larger ones. We investigate here numerical data on the country-wise adherent distribution of seven major world religions i.e. Christianity, Islam, Buddhism, Hinduism, Sikhism, Judaism and Baha'ism to see if the proportion of the leading digits occurring in the distribution conforms to Benford's law. We find that the adherent data of all the religions, except Christianity, excellently does conform to Benford's law. Furthermore, unlike the adherent data on Christianity, the significant digit distribution of the three major Christian denominations i.e. Catholicism, Protestantism and Orthodoxy obeys the law. Thus in spite of their complexity general laws can be established for the evolution of religious groups.

  9. 24 CFR 115.204 - Criteria for adequacy of law.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... HUD's implementing regulations found at 24 CFR part 100. (b) In addition to the factors described in... persons, as described in 24 CFR part 100, subpart E. (e) A determination of the adequacy of a state or... assessment of punitive damages against the respondent. (2) If an agency's law offers an...

  10. A Data Analysis for the Inverse Square Law

    NASA Astrophysics Data System (ADS)

    Downie, Russell

    2007-04-01

    When first encountered, inverse square laws can damage the confidence of beginning physics students whose maths skills are uncertain. Engaging in practical exercises that help them work with the idea can be a great help. We have used the following apparatus for a number of years and our students understand and enjoy the exercise.

  11. Corrosion Damage Functions

    SciTech Connect

    Jones, Russell H.

    2002-11-30

    Corrosion damage can lead to reduced operational lifetimes. Often this damage is not as obvious as general corrosion but takes the form of pits, intergranular corrosion, crevice corrosion and hydrogen absorption. These types of corrosion damage lead to stress corrosion cracking, hydrogen induced cracking and corrosion fatigue. A critical step in defining a corrosion damage function is determining the relationship between the corrosion damage, the resulting crack propagation mechanism and component lifetimes. The sequence of events is often some localized corrosion event such as pitting, transition of the pit to a planar crack, propagation of this short crack, transition of the short crack to long crack conditions and continued propagation through Stage I, II, and III of the long crack SCC regimes. A description of critical corrosion damage processes and examples of the transition to long crack SCC conditions will be discussed.

  12. Integrated Modelling of Damage and Fracture in Sheet Metal Forming

    NASA Astrophysics Data System (ADS)

    Peerlings, R. H. J.; Mediavilla, J.; Geers, M. G. D.

    2007-05-01

    A framework for finite element simulations of ductile damage development and ductile fracture during metal forming is presented. The damage evolution is described by a phenomenological continuum damage model. Crack growth and fracture are treated as the ultimate consequences of the damage process. Computationally, the initiation and growth of cracks is traced by an adaptive remeshing strategy, thereby allowing for opening crack faces. The application of the method to the fabrication of food-can lids demonstrates its capabilities, but also some of its limitations.

  13. Physical Laws for Mechanobiology

    NASA Technical Reports Server (NTRS)

    Freed, Alan D.

    2007-01-01

    Higher-level physical laws applicable to biological tissues are presented that will permit the modeling of metabolic activity at the cellular level, including variations in the mass of a tissue. Here the tissue is represented as a fluid/solid mixture, wherein molecular solutes transport within the fluid, and cells can migrate throughout the porous solid. Variations in mass can arise via exchanges in mass between the constituent phases within a control volume such that mass is conserved in the tissue overall. The governing balance laws for mass, momentum, energy, and entropy are a special case of those describing a chemically reacting mixture with diffusion. Thermodynamic constraints on the constitutive structure are addressed. Biophysics; Biomechanics; Brownian motion; Cell migration; Mixture theory; Thermodynamic laws; Tissue mechanics

  14. Damage Tolerance of Composites

    NASA Technical Reports Server (NTRS)

    Hodge, Andy

    2007-01-01

    Fracture control requirements have been developed to address damage tolerance of composites for manned space flight hardware. The requirements provide the framework for critical and noncritical hardware assessment and testing. The need for damage threat assessments, impact damage protection plans, and nondestructive evaluation are also addressed. Hardware intended to be damage tolerant have extensive coupon, sub-element, and full-scale testing requirements in-line with the Building Block Approach concept from the MIL-HDBK-17, Department of Defense Composite Materials Handbook.

  15. Law of the Sea

    SciTech Connect

    Borgese, E.M.

    1983-03-01

    Seabed development will proceed even though the US declined to join 119 nations signing the Law of the Sea Treaty. The new law replaces laissez faire development with management of the seas. The US, Soviet Union, and 15 other countries, while withholding their signatures from the convention, did sign the Final Act of the Conference and can sign as full participants in the future if they choose. The new management approach considers global socio-economic and resource needs. It emphasizes international cooperation in the areas of economic development, disarmament, and in establishing rules and regulations for exploring the seabed. (DCK)

  16. Anisotropic Damage Analysis of HY100 Steel Under Quasistatic Loading Conditions

    SciTech Connect

    Los Alamos National Laboratory

    2001-01-01

    The effect of MnS inclusion orientation on damage evolution and fracture toughness in HYlOO steel is investigated in the context of anisotropic damage modeling at the continuum level. Experimental notched-bar data sets are analyzed and modeled using finite element calculations with constitutive behavior that assumes isotropic elastoplastic behavior in conjunction with anisotropic damage.

  17. 29 CFR 6.19 - Decision of the Administrative Law Judge.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Administrative Law Judge shall make no findings regarding liquidated damages under the Contract Work Hours and... 29 Labor 1 2011-07-01 2011-07-01 false Decision of the Administrative Law Judge. 6.19 Section 6.19... Proceedings Under the Service Contract Act (and Under the Contract Work Hours and Safety Standards Act...

  18. 29 CFR 6.19 - Decision of the Administrative Law Judge.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Administrative Law Judge shall make no findings regarding liquidated damages under the Contract Work Hours and... 29 Labor 1 2010-07-01 2010-07-01 true Decision of the Administrative Law Judge. 6.19 Section 6.19... Proceedings Under the Service Contract Act (and Under the Contract Work Hours and Safety Standards Act...

  19. The Evolution of Complex Life

    NASA Technical Reports Server (NTRS)

    Billingham, John

    1989-01-01

    In considering the probabilities that intelligent life might exist elsewhere in the Universe, it is important to ask questions about the factors governing the emergence of complex living organisms in the context of evolutionary biology, planetary environments and events in space. Two important problems arise. First, what can be learned about the general laws governing the evolution of complex life anywhere in space by studying its history on the Earth? Second, how is the evolution of complex life affected by events in space? To address these problems, a series of Science Workshops on the Evolution of Complex Life was held at the Ames Research Center. Included in this paper are highlights of those workshops, with particular emphasis on the first question, namely the evolution of complex extraterrestrial life.

  20. Repair of UV damage in bacteria.

    PubMed

    Goosen, Nora; Moolenaar, Geri F

    2008-03-01

    From the start of the first primitive life forms on earth ultraviolet (UV) light has been a seriously threatening factor. UV light is absorbed by the DNA causing several types of damage that can interfere with transcription and replication. In bacteria a number of different repair mechanisms have evolved to repair these UV-induced lesions. These mechanisms include direct reversal of the damage by a photolyase (photoreactivation), removing of the damaged base by a DNA glycosylase (base excision repair, BER), incision of the DNA adjacent to the damage by an endonuclease (UV-damage endonuclease, UVDE) or removal of a complete oligonucleotide containing the damage (nucleotide excision repair, NER). This paper presents an inventory of genes encoding enzymes involved in these repair pathways based on the analysis of complete genome sequences of a large number of eubacteria and archaebacteria. From the comparison of homologous sequences between the different species a picture emerges how the repair systems have been transmitted during evolution. In addition, a comparative analysis of amino acid sequences of homologous proteins allows the prediction of specific functions in as yet uncharacterized proteins or protein domains. PMID:17951115

  1. Diffusion Processes Satisfying a Conservation Law Constraint

    DOE PAGESBeta

    Bakosi, J.; Ristorcelli, J. R.

    2014-03-04

    We investigate coupled stochastic differential equations governing N non-negative continuous random variables that satisfy a conservation principle. In various fields a conservation law requires that a set of fluctuating variables be non-negative and (if appropriately normalized) sum to one. As a result, any stochastic differential equation model to be realizable must not produce events outside of the allowed sample space. We develop a set of constraints on the drift and diffusion terms of such stochastic models to ensure that both the non-negativity and the unit-sum conservation law constraint are satisfied as the variables evolve in time. We investigate the consequencesmore » of the developed constraints on the Fokker-Planck equation, the associated system of stochastic differential equations, and the evolution equations of the first four moments of the probability density function. We show that random variables, satisfying a conservation law constraint, represented by stochastic diffusion processes, must have diffusion terms that are coupled and nonlinear. The set of constraints developed enables the development of statistical representations of fluctuating variables satisfying a conservation law. We exemplify the results with the bivariate beta process and the multivariate Wright-Fisher, Dirichlet, and Lochner’s generalized Dirichlet processes.« less

  2. Diffusion Processes Satisfying a Conservation Law Constraint

    SciTech Connect

    Bakosi, J.; Ristorcelli, J. R.

    2014-03-04

    We investigate coupled stochastic differential equations governing N non-negative continuous random variables that satisfy a conservation principle. In various fields a conservation law requires that a set of fluctuating variables be non-negative and (if appropriately normalized) sum to one. As a result, any stochastic differential equation model to be realizable must not produce events outside of the allowed sample space. We develop a set of constraints on the drift and diffusion terms of such stochastic models to ensure that both the non-negativity and the unit-sum conservation law constraint are satisfied as the variables evolve in time. We investigate the consequences of the developed constraints on the Fokker-Planck equation, the associated system of stochastic differential equations, and the evolution equations of the first four moments of the probability density function. We show that random variables, satisfying a conservation law constraint, represented by stochastic diffusion processes, must have diffusion terms that are coupled and nonlinear. The set of constraints developed enables the development of statistical representations of fluctuating variables satisfying a conservation law. We exemplify the results with the bivariate beta process and the multivariate Wright-Fisher, Dirichlet, and Lochner’s generalized Dirichlet processes.

  3. Evaluating glaucoma damage: emerging imaging technologies

    PubMed Central

    Kostanyan, Tigran; Wollstein, Gadi; Schuman, Joel S

    2015-01-01

    The use of ocular imaging tools to estimate structural and functional damage in glaucoma has become a common clinical practice and a substantial focus of vision research. The evolution of the imaging technologies through increased scanning speed, penetration depth, image registration and development of multimodal devices has the potential to detect the pathology more reliably and in earlier stages. This review is focused on new ocular imaging modalities used for glaucoma diagnosis. PMID:27087829

  4. [Cloning and law in Hungary].

    PubMed

    Julesz, Máté

    2015-03-01

    Reproductive human cloning is prohibited in Hungary, as in many other countries. Therapeutic human cloning is not prohibited, just like in many other countries. Stem cell therapy is also allowed. Article III, paragraph (3) of the Hungarian basic law (constitution) strictly forbids total human cloning. Article 1 of the Additional Protocol to the Oviedo Convention, on the Prohibition of Cloning Human Beings (1998) stipulates that any intervention seeking to create a human being genetically identical to another human being, whether living or dead, is prohibited. In Hungary, according to Article 174 of the Criminal Code, total human cloning constitutes a crime. Article 180, paragraph (3) of the Hungarian Act on Health declares that embryos shall not be brought about for research purposes; research shall be conducted only on embryos brought about for reproductive purposes when this is authorized by the persons entitled to decide upon its disposal, or when the embryo is damaged. Article 180, paragraph (5) of the Hungarian Act on Health stipulates that multiple individuals who genetically conform to one another shall not be brought about. According to Article 181, paragraph (1) of the Hungarian Act on Health, an embryo used for research shall be kept alive for not longer than 14 days, not counting the time it was frozen for storage and the time period of research. PMID:25749537

  5. Law of universal mortality.

    PubMed

    Azbel', Mark Ya

    2002-07-01

    Mortality is arguably the best statistically quantified biological phenomenon. This allows for a physical approach to its study. I establish that in well protected populations, a dominant fraction of mortality at a given age depends on a single parameter only. Such invariance to any other time and space changes is known only in general relativity. It is so mathematically restrictive that, with no other knowledge of experimental data, it is sufficient to predict the exact law. It is universal for species as remote as humans and flies. The law unravels its biologically nonspecific thermodynamic mechanism. It implies that within a couple of years human mortality may be reset to its value at a much younger age. The reversal (albeit not yet as rapid) is consistent with demographic data. For instance, Swedish females, born in 1916, at 48 yr restored their mortality rate 28 yr earlier. The law and its other predictions and implications are also verified. The universal law suggests that a dominant fraction of mortality in well protected populations is just a by-product, which may be eliminated. Total mortality can be significantly decreased. PMID:12241426

  6. The Gas Laws

    ERIC Educational Resources Information Center

    Raman, V. V.

    1973-01-01

    Inquires into the individual names and dates which are associated with the various perfect gas laws on the basis of published and historically researched works. Indicates the presence of eight features in giving a scientist credit for a scientific discovery. (CC)

  7. Demonstrating Newton's Second Law.

    ERIC Educational Resources Information Center

    Fricker, H. S.

    1994-01-01

    Describes an apparatus for demonstrating the second law of motion. Provides sample data and discusses the merits of this method over traditional methods of supplying a constant force. The method produces empirical best-fit lines which convincingly demonstrate that for a fixed mass, acceleration is proportional to force. (DDR)

  8. School Law Update, 1985.

    ERIC Educational Resources Information Center

    Jones, Thomas N., Ed.; Semler, Darel P., Ed.

    A wide variety of contemporary legal issues, involving all levels of public and private education, are addressed in the 20 papers in this volume. Written in law review style and including legal citations, the papers and authors included are: (1) "Who Runs the Schools" (Flygare); (2) "Copyright Issues in Computer-Assisted Instruction" (Helm); (3)…

  9. Public Relations & the Law.

    ERIC Educational Resources Information Center

    Walsh, Frank

    This monograph synthesizes the laws and regulations that form the basis of the right to representation in the court of public opinion by all who would seek to influence public and private decisions. It expresses the framework of human and social values that underlie this constitutional freedom and that give public relations and other management…

  10. Law and the Consumer.

    ERIC Educational Resources Information Center

    Idleman, Hillis K.

    One of eleven modules developed for secondary school consumer education, this document emphasizes the need of the consumer, especially the disadvantaged consumer, to understand the law and the protection it can offer. The material is presented in three columns: understandings (usually formulated as questions followed by commentary), suggested…

  11. Team Teaching School Law

    ERIC Educational Resources Information Center

    Vanko, John G.; Rogina, Raymond P.

    2005-01-01

    Graduate students preparing themselves for a career in school administration are typically apprehensive about the legal issues they will face in their first administrative position. After teaching school law for the first time, the author believed that there had to be a more effective way to reach these students rather than the traditional methods…

  12. Law and Ecomanagement.

    ERIC Educational Resources Information Center

    Mayda, Jaro

    1986-01-01

    This article argues that environmental awareness has a substantial impact on law, both as a technical discipline and as a policy process. It further develops the concept of ecomanagement and reviews the role of environmental impact assessments in policy development. (JDH)

  13. School Law Issue.

    ERIC Educational Resources Information Center

    Update on Law-Related Education, 1994

    1994-01-01

    This law-related education teaching resource calls attention to civil rights in the school. Julius Menacker gives an overview of major national school legislation and the federal courts' roles in the constitutional areas of equal protection, freedom of expression, and due process. Aggie Alvez offers new perspectives on the constitutional,

  14. [Epilepsy and Canon Law].

    PubMed

    Bonduelle, M

    1987-01-01

    The Canon Law (Codex Iuris Canonici), promulgated in 1917, was a classification of laws and jurisprudence which ruled the early Church, governed the ecclesiastical condition of Roman Church until its reorganisation in 1983. It forbade to be ordained or to exercise orders already received to "those who are or were epileptics either not quite in their right mind or possessed by the Evil One". All the context and in particular the paragraph which treated of bodily lacks, indicated that between these three conditions, there was juxtaposition and no confusion. The texts specified the foundations of these dispositions, not in a malefic view of epilepsy inherited from Morbus Sacer of Antiquity, but in decency and on account of risk incured by Eucharist in case of fit. Some derogations could attenuate the severity of these dispositions--as jurisprudence had taken progresses of Epileptology and therapeutics into consideration. In the new Code of Canon Law (1983) physical disabilities were removed from the text and also possessed evil and epilepsy, the only impediment being "insanity or other psychic defect" appreciation of which is done by experts. Concerning poorly controlled epilepsies, we believe that experts will be allowed to express their opinion and a new jurisprudence will make up for the silence of the law. PMID:3310183

  15. Discipline and the Law.

    ERIC Educational Resources Information Center

    Zirkel, Perry A.

    1996-01-01

    Some superintendents'"zero-tolerance" stance on guns, drugs, and disruptive student behavior conflicts with federal laws (Individuals with Disabilities Act and Americans with Disabilities Act), which apply a "zero-reject" policy to many categories of students with disabilities. Superintendents should revamp policies and practices and think twice…

  16. Environment Law Review--1970.

    ERIC Educational Resources Information Center

    Sherrod, H. Floyd; And Others

    This is the first of several volumes to be published annually in the field of environmental law. It contains material from periodicals published in early 1970, 1969, and several articles of special significance which appeared in periodicals bearing 1968 dates. It has been collected primarily for lawyers so they may have, in convenient reference…

  17. Protective Policy Laws.

    ERIC Educational Resources Information Center

    Gehrin, Donald D.

    1994-01-01

    Offers ways to help student affairs administrators understand protective policy laws and regulations. Looks at how such federal guidelines affect campus policies, practices, and procedures. Examines the Buckley Amendment, student consumer information, student right-to-know, campus security, and the Drug Free Schools and Communities Act. (Includes…

  18. Law Related Education.

    ERIC Educational Resources Information Center

    Maslow, R., Ed.; Kirchgaessner, R., Ed.

    1989-01-01

    This journal edition focuses upon the many resources for teachers to draw upon in order to infuse law-related education (LRE) into their classrooms. Isidore Starr explains the reasons behind the LRE movement, while Mabel McKinney-Browning describes the existing American Bar Association's programs in LRE. Judith Zimmer covers the Street Law…

  19. Environment Law Review--1970.

    ERIC Educational Resources Information Center

    Sherrod, H. Floyd; And Others

    This is the first of several volumes to be published annually in the field of environmental law. It contains material from periodicals published in early 1970, 1969, and several articles of special significance which appeared in periodicals bearing 1968 dates. It has been collected primarily for lawyers so they may have, in convenient reference

  20. Financial Disclosure Laws.

    ERIC Educational Resources Information Center

    Merz, Carol

    1983-01-01

    A study of school board presidents and superintendents in Washington, Missouri, and New Jersey reveals that strict financial disclosure laws tend to reduce the number of professionals on boards; however, board members with professional occupations differ from other board members on a number of measures. (MLF)

  1. Environmental Law II.

    ERIC Educational Resources Information Center

    Continuing Legal Education in Colorado, Inc., Denver.

    Presented are papers delivered at a 1976 Colorado environmental law conference. Included in the publication are the conference schedule, the text of nine papers, background information on authors, and bibliography listings for each paper. Titles and topics of the papers are the following: (1) Water Resources Development and the Environment…

  2. Discretion in Administrative Law.

    ERIC Educational Resources Information Center

    Grey, J.

    1979-01-01

    Clarifies the concept of discretion, demonstrates how far the courts have been willing to tolerate it, and charts some new paths that appear to be opening before those who advocate wide judicial review. Available from the Osgoode Hall Law School, York University, 4700 Keele Street, Downsview, Ontario, Canada, M3J 2R5; $8.00/issue. (Author/IRT)

  3. School Law: Background Checks.

    ERIC Educational Resources Information Center

    Splitt, David A.

    1988-01-01

    In an Oklahoma case, the district court ruled that the school district had failed to investigate the background of a teacher convicted of a second sexual abuse charge. School districts should examine personnel polices and practices, and the school lawyer should review state laws, regulations, and court cases. (MLF)

  4. The Law and Desegregation.

    ERIC Educational Resources Information Center

    Weinberg, Meyer, Ed.; And Others

    1978-01-01

    This report reviews and analyzes six books on the subject of the law and racial equality, especially as related to school desegregation. The books examined are: (1)"Government by Judiciary" by Raoul Berger, which examines the Supreme Court's interpretation of the 14th Amendment; (2) "Disaster by Decree," by Lino A. Graglia, which criticizes…

  5. Law as Focus.

    ERIC Educational Resources Information Center

    Blythe, Joan Heiges

    1989-01-01

    Shows how teachers can increase students' general appreciation of literature and improve students' writing skills by studying literature with legal issues and images of the law. Cites several examples of such literature, including Geoffrey Chaucer's "Canterbury Tales," William Shakespeare's "Measure for Measure," and Jonathan Swift's "Gulliver's…

  6. Preventive Law Curriculum Guide.

    ERIC Educational Resources Information Center

    Henderson, Martha V.; Gullatt, David E.; Hardin, Dawn T.; Jannik, Catherine; Tollett, John R.

    This curriculum guide presents a context for preservice education and/or professional development in education law for teachers. Section 1, "Teacher Liability," discusses "Duty to Supervise,""Providing Reasonable Care,""Duty,""Preventing Student-to-Student Sexual Harassment,""Reporting Child Abuse,""Issuing Permission Slips,""Defense for…

  7. ADHD and School Law.

    ERIC Educational Resources Information Center

    Gregg, Soleil

    A review of the research and legal literature summarizes the status of attention deficit hyperactivity disorder (ADHD) under school law. Following a brief introduction, discussion of ADHD as a disability notes the impact of ADHD on overall functioning and provides a table of diagnostic criteria for subtypes of ADHD. The following section focuses…

  8. Teaching Evolution

    ERIC Educational Resources Information Center

    Bryner, Jeanna

    2005-01-01

    Eighty years after the famous 1925 Scopes "monkey trial," which tested a teacher's right to discuss the theory of evolution in the classroom, evolution--and its most recent counterview, called "intelligent design"--are in the headlines again, and just about everyone seems to have an opinion. This past July, President Bush weighed in, telling…

  9. FTS evolution

    NASA Technical Reports Server (NTRS)

    Provost, David E.

    1990-01-01

    Viewgraphs on flight telerobotic servicer evolution are presented. Topics covered include: paths for FTS evolution; frequently performed actions; primary task states; EPS radiator panel installation; generic task definitions; path planning; non-contact alignment; contact planning and control; and human operator interface.

  10. A damage mechanics based approach to structural deterioration and reliability

    SciTech Connect

    Bhattcharya, B.; Ellingwood, B.

    1998-02-01

    Structural deterioration often occurs without perceptible manifestation. Continuum damage mechanics defines structural damage in terms of the material microstructure, and relates the damage variable to the macroscopic strength or stiffness of the structure. This enables one to predict the state of damage prior to the initiation of a macroscopic flaw, and allows one to estimate residual strength/service life of an existing structure. The accumulation of damage is a dissipative process that is governed by the laws of thermodynamics. Partial differential equations for damage growth in terms of the Helmholtz free energy are derived from fundamental thermodynamical conditions. Closed-form solutions to the equations are obtained under uniaxial loading for ductile deformation damage as a function of plastic strain, for creep damage as a function of time, and for fatigue damage as function of number of cycles. The proposed damage growth model is extended into the stochastic domain by considering fluctuations in the free energy, and closed-form solutions of the resulting stochastic differential equation are obtained in each of the three cases mentioned above. A reliability analysis of a ring-stiffened cylindrical steel shell subjected to corrosion, accidental pressure, and temperature is performed.

  11. Clarifying Baker's Law

    PubMed Central

    Cheptou, P.-O.

    2012-01-01

    Background Baker's Law states that colonization by self-compatible organisms is more likely to be successful than colonization by self-incompatible organisms because of the ability for self-compatible organisms to produce offspring without pollination agents. This simple model has proved very successful in plant ecology and has been applied to various contexts, including colonizing or ruderal species, islands colonizers, invasive species or mating system variation across distribution ranges. Moreover, it is one of the only models in population biology linking two traits of major importance in ecology, namely dispersal and mating system. Although Baker's Law has stimulated a large number of empirical studies reporting the association of self-fertilization and colonizing ability in various contexts, the data have not established a general pattern for the association of traits. Scope In this paper, a critical position is adopted to discuss and clarify Baker's Law. From the literature referring to Baker's Law, an analysis made regarding how mating success is considered in such studies and discrepancies with population genetics theory of mating systems are highlighted. The data reporting the association of self-fertilization and colonizing ability are also briefly reviewed and the potential bias in interpretation is discussed. Lastly, a recent theoretical model analysing the link between colonizing ability and self-fertilization is considered. Conclusions Evolutionary predictions are actually more complex than Baker's intuitive arguments. It appears that Baker's Law encompasses a variety of ecological scenarios, which cannot be considered a priori as equivalent. Questioning what has been considered as self-evident for more than 50 years seems a reasonable objective to analyse in-depth dispersal and mating system traits. PMID:21685434

  12. Hagfors' law revisited

    NASA Astrophysics Data System (ADS)

    Sultan-Salem, Ahmed K.; Tyler, G. Leonard

    2006-04-01

    Hagfors' scattering law, σ°H($\\theta$), is in wide use in connection with the study of backscatter data from planetary surfaces because it provides good agreement with a variety of observations. The surface root-mean-square slope inferred on the basis of σ°H($\\theta$) is customarily taken as C-1/2, where C is the shape parameter in σ°H($\\theta$). The relationship between the surface slope and C is indefinite, however, because of the indeterminateness of the surface scales contributing to the scattering process. Moreover, the horizontal scale of the inferred slope obtained is not specified. As a consequence of limitations in the Kirchhoff approximation on which it is predicated, σ°H($\\theta$) does not conserve energy. The use of a fractional Brownian fractal surface model leads to a scattering law with the same functional form as σ°H($\\theta$) when the Hurst exponent characterizing the fractal model is 1/2. Fractal-based scattering laws, derived by applying the Kirchhoff approximation, suffer the same deficiency with regard to conservation of energy. In contrast to σ°H($\\theta$), slope information for fractal-based laws is explicit with respect to horizontal scale. Both σ°H($\\theta$) and fractal-based laws require that the illuminated surface area exceeds a certain value, which is a function of the electromagnetic wavelength and surface parameters, in order to reduce the surface radar cross section overestimation error, introduced by a mathematical approximation, below some specified value. This requirement may be necessary to take into account in experiments where the radar resolution cells are comparable in size to the wavelength, such as in Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS).

  13. Guest Editorial: Laser Damage

    SciTech Connect

    Vitaly Gruzdev, Michelle D. Shinn

    2012-12-01

    Laser damage of optical materials, first reported in 1964, continues to limit the output energy and power of pulsed and continuous-wave laser systems. In spite of some 48 years of research in this area, interest from the international laser community to laser damage issues remains at a very high level and does not show any sign of decreasing. Moreover, it grows with the development of novel laser systems, for example, ultrafast and short-wavelength lasers that involve new damage effects and specific mechanisms not studied before. This interest is evident from the high level of attendance and presentations at the annual SPIE Laser Damage Symposium (aka, Boulder Damage Symposium) that has been held in Boulder, Colorado, since 1969. This special section of Optical Engineering is the first one devoted to the entire field of laser damage rather than to a specific part. It is prepared in response to growing interest from the international laser-damage community. Some papers in this special section were presented at the Laser Damage Symposium; others were submitted in response to the general call for papers for this special section. The 18 papers compiled into this special section represent many sides of the broad field of laser-damage research. They consider theoretical studies of the fundamental mechanisms of laser damage including laser-driven electron dynamics in solids (O. Brenk and B. Rethfeld; A. Nikiforov, A. Epifanov, and S. Garnov; T. Apostolova et al.), modeling of propagation effects for ultrashort high-intensity laser pulses (J. Gulley), an overview of mechanisms of inclusion-induced damage (M. Koldunov and A. Manenkov), the formation of specific periodic ripples on a metal surface by femtosecond laser pulses (M. Ahsan and M. Lee), and the laser-plasma effects on damage in glass (Y. Li et al). Material characterization is represented by the papers devoted to accurate and reliable measurements of absorption with special emphasis on thin films (C. Mühlig and S. Bublitz; B. Cho, E. Danielewicz, and J. Rudisill; W. Palm et al; and J. Lu et al.). Statistical treatment of measurements of the laser-damage threshold (J. Arenberg) and the relationship to damage mechanisms (F. Wagner et al.) represent the large subfield of laser-damage measurements. Various aspects of multilayer coating and thin-film characterization are considered in papers by B. Cho, J. Rudisill, and E. Danielewicz (spectral shift in multilayer mirrors) and R. Weber et al. (novel approach to damage studies based on third-harmonic generation microscopy). Of special interest for readers is the paper by C. Stolz that summarizes the results of four “thin-film damage competitions” organized as a part of the Laser Damage Symposium. Another paper is devoted to thermal annealing of damage precursors (N. Shen et al.). Finally, the influence of nano-size contamination on initiation of laser damage by ultrashort pulses is considered in paper of V. Komolov et al.

  14. A Quantitative Examination Whether Education Mitigates Stress Levels among Law Enforcement Officers

    ERIC Educational Resources Information Center

    Metts, Gary A.

    2012-01-01

    Stress is damaging if it is continual, overwhelming. and prolonged. Law enforcement officers face stressful events daily. A relationship exists between stress levels and the physical and psychological effects to the human body. Although there is a general understanding of the damage stress can do physically and psychologically, many elements that…

  15. A Quantitative Examination Whether Education Mitigates Stress Levels among Law Enforcement Officers

    ERIC Educational Resources Information Center

    Metts, Gary A.

    2012-01-01

    Stress is damaging if it is continual, overwhelming. and prolonged. Law enforcement officers face stressful events daily. A relationship exists between stress levels and the physical and psychological effects to the human body. Although there is a general understanding of the damage stress can do physically and psychologically, many elements that

  16. Living Dangerously--Changing Press Law in India.

    ERIC Educational Resources Information Center

    Ryan, Timothy

    An examination of the changes in press laws after India gained its independence in 1947 shows how a free press is shaped mostly by the structure and evolution of the democratic society that it is intended to serve. The most salient features that have characterized the Indian press, from the early nineteenth century to the present day, are…

  17. Conservation laws, differential identities, and constraints of partial differential equations

    NASA Astrophysics Data System (ADS)

    Zharinov, V. V.

    2015-11-01

    We consider specific cohomological properties such as low-dimensional conservation laws and differential identities of systems of partial differential equations (PDEs). We show that such properties are inherent to complex systems such as evolution systems with constraints. The mathematical tools used here are the algebraic analysis of PDEs and cohomologies over differential algebras and modules.

  18. Metabolite Damage and Metabolite Damage Control in Plants.

    PubMed

    Hanson, Andrew D; Henry, Christopher S; Fiehn, Oliver; de Crécy-Lagard, Valérie

    2016-04-29

    It is increasingly clear that (a) many metabolites undergo spontaneous or enzyme-catalyzed side reactions in vivo, (b) the damaged metabolites formed by these reactions can be harmful, and (c) organisms have biochemical systems that limit the buildup of damaged metabolites. These damage-control systems either return a damaged molecule to its pristine state (metabolite repair) or convert harmful molecules to harmless ones (damage preemption). Because all organisms share a core set of metabolites that suffer the same chemical and enzymatic damage reactions, certain damage-control systems are widely conserved across the kingdoms of life. Relatively few damage reactions and damage-control systems are well known. Uncovering new damage reactions and identifying the corresponding damaged metabolites, damage-control genes, and enzymes demands a coordinated mix of chemistry, metabolomics, cheminformatics, biochemistry, and comparative genomics. This review illustrates the above points using examples from plants, which are at least as prone to metabolite damage as other organisms. PMID:26667673

  19. Space law - Current status and issues

    NASA Technical Reports Server (NTRS)

    Hosenball, S. N.

    1983-01-01

    The evolution of space law over the past 25 years is surveyed, with attention also given to the procedures that were followed. The treaties now in existence are given, as are issues currently before the United Nations Committee on the Peaceful Uses of Outer Space. Projections that were made 25 years ago are discussed in the light of subsequent developments. It is noted that nearly all the technological advances in space activities forecast 25 years ago have come to pass. Various provisions of the 1967 Outer Space Principles Treaty relating to stricture against weapons and the militarization of space are discussed.

  20. Hubble's Law Implies Benford's Law for Distances to Galaxies

    NASA Astrophysics Data System (ADS)

    Hill, Theodore P.; Fox, Ronald F.

    2016-03-01

    A recent article by Alexopoulos and Leontsinis presented empirical evidence that the first digits of the distances from the Earth to galaxies are a reasonably good fit to the probabilities predicted by Benford's law, the well known logarithmic statistical distribution of significant digits. The purpose of the present article is to give a theoretical explanation, based on Hubble's law and mathematical properties of Benford's law, why galaxy distances might be expected to follow Benford's law. The new galaxy-distance law derived here, which is robust with respect to change of scale and base, to additive and multiplicative computational or observational errors, and to variability of the Hubble constant in both time and space, predicts that conformity to Benford's law will improve as more data on distances to galaxies becomes available. Conversely, with the logical derivation of this law presented here, the recent empirical observations may be viewed as independent evidence of the validity of Hubble's law.

  1. The Legitimacy of Punitive Damages in Media Libel Cases.

    ERIC Educational Resources Information Center

    Thomas, James H.

    The constitutionality of punitive damage awards in media defamation litigation was examined through a review of federal and state libel case law since the 1964 Supreme Court decision in "New York Times v. Sullivan." Using the opinions of various courts and justices and studies of libel litigation, a number of areas bearing on the issue were…

  2. The Environmental Law Handbook.

    ERIC Educational Resources Information Center

    Landau, Norman J.; Rheingold, Paul D.

    Designed for conservation groups from laymen to lawyers, this handbook tells how polluters and despoilers of our environment can be brought to court in civil actions and compelled to desist and pay damages. It shows how to prepare a case and gives relevant information on pleadings and complaints, answers, motions and briefs; cites statutes and…

  3. Stellar evolution.

    NASA Technical Reports Server (NTRS)

    Chiu, H.-Y. (Editor); Muriel, A.

    1972-01-01

    Aspects of normal stellar evolution are discussed together with evolution near the main sequence, stellar evolution from main sequence to white dwarf or carbon ignition, the structure of massive main-sequence stars, and problems of stellar stability and stellar pulsation. Other subjects considered include variable stars, white dwarfs, close binaries, novae, early supernova luminosity, neutron stars, the photometry of field horizontal-branch stars, and stellar opacity. Transport mechanisms in stars are examined together with thermonuclear reactions and nucleosynthesis, the instability problem in nuclear burning shells, stellar coalescence, and intense magnetic fields in astrophysics. Individual items are announced in this issue.

  4. Vermont Law School's Unique Master of Studies in Environmental Law.

    ERIC Educational Resources Information Center

    Suagee, Dean B.

    2003-01-01

    Vermont Law School offers a 1-year master of studies in environmental law for which the only prerequisite is a bachelor's degree. A fellowship program waives tuition and provides stipends for American Indians taking the program. Courses on federal Indian law complement the program. The Native community at nearby Dartmouth College provides social…

  5. DNA Damage Response

    PubMed Central

    Giglia-Mari, Giuseppina; Zotter, Angelika; Vermeulen, Wim

    2011-01-01

    Structural changes to DNA severely affect its functions, such as replication and transcription, and play a major role in age-related diseases and cancer. A complicated and entangled network of DNA damage response (DDR) mechanisms, including multiple DNA repair pathways, damage tolerance processes, and cell-cycle checkpoints safeguard genomic integrity. Like transcription and replication, DDR is a chromatin-associated process that is generally tightly controlled in time and space. As DNA damage can occur at any time on any genomic location, a specialized spatio-temporal orchestration of this defense apparatus is required. PMID:20980439

  6. War Damage Assessment

    NASA Technical Reports Server (NTRS)

    1994-01-01

    During and after the Persian Gulf war, hundreds of "oil lakes" were created in Kuwait by oil released from damaged wells. The lakes are a hazard to the Kuwait atmosphere, soil and ground water and must be carefully monitored. Boston University Center for Remote Sensing, assisted by other organizations, has accurately mapped the lakes using Landsat and Spot imagery. The war damage included the formation of over 300 oil lakes, oil pollution and sand dune movement. Total damage area is over 5,400 square kilometers - 30 percent of Kuwait's total surface area.

  7. Registration law proposed

    NASA Astrophysics Data System (ADS)

    Richman, Barbara T.

    A proposal has been submitted to a New Jersey state senator for a state law that would establish a noncompulsory registration program to identify qualified professional geologists and soil scientists. The proposal, which would create a registration law similar to those in other states, is supported by the membership of the Northeast Section of the American Institute of Professional Geologists (AIPG) and by the New Jersey Association of Professional Soil Scientists (NJAPSS).The proposal, drawn up by the membership of the Northeast Section of AIPG (which includes the six New England states, New York, and New Jersey) in cooperation with NJAPSS and the New York-Philadelphia section of the Association of Engineering Geology, has been submitted to Democratic State Senator Raymond J. Zane. The senator's staff has indicated that they will review the proposal and refine it for presentation to the entire state senate, according to Richard H. Young, vice president of AIPG's northeastern section.

  8. On electromagnetic conservation laws

    NASA Astrophysics Data System (ADS)

    Goedecke, G. H.

    2000-04-01

    Subdivision of any charge-current source into N separately conserved sources results in N(N+1)/2 separate conservation laws for each of the interesting electromagnetic quantities, energy, momentum, and angular momentum. The subdivision may be done arbitrarily, so N is also arbitrary. These separate conservation laws are derived and applied to several examples, including the Fourier series representation of any time-dependent source, the derivation of the optical theorem in scattering, the energy balance for a resistor carrying a steady current, and the force on one charged capacitor plate due to the other. A general result is that the Lorentz force exerted by any static source on itself is zero. Other applications are also discussed.

  9. Bridging the scales with statistical damage mechanics

    NASA Astrophysics Data System (ADS)

    Rinaldi, Antonio

    An important task in damage mechanics is to estimate the damage tolerance of a structure when micro-cracks form in the microstructure. This dissertation focuses mostly on quasi-brittle materials, such as some polycrystalline ceramics, which undergo a homogeneous-heterogeneous transition. Large data scatter and size effects characterize the softening phase. Discrete models provide reliable estimates of macro-parameters also in the softening phase. The microstructure is represented by two-dimensional disordered lattices that capture the randomness of geometrical, topological and mechanical properties on the micro-scale. A rigorous procedure for the calibration of lattices from experimental data is proposed. The proper definition of the damage parameter D for the lattice and the formulation of analytical constitutive relations are identified from numerical data of static tensile tests. A novel two-steps scaling procedure is developed providing the scaling laws for D necessary to model the size effects. Our analysis suggests the existence of a maximum dissipation principle governing the micro-scale energy redistribution when new damage forms. Damage-controlled simulations are used to detect "snapbacks" and clarify their connection with large avalanches near the critical point. Detailed examination of micro-fields establishes the statistical foundations of D in the hardening phase. A new perspective emerges concerning the key-role of the micro-perturbation induced by the damage. The notion of damage nucleation as a partially-correlated process is introduced based of the distinction between primary and secondary broken links. Such distinction reflects in D and is relevant for multiaxial loading. An alternative pseudo-empirical model, based on numerical data and extreme value theory, is also formulated to capture both data scatter and size effects. Two applications of discrete modeling for fatigue and plasticity are presented. By adding a micro damage accumulation rule, fatigue-damage is investigated in strain-controlled cycling. Surprisingly, the fatigue life data from simulations are described by the same statistical distributions, such as Lognormal and Weibull, commonly encountered experimentally and in reliability models. Finally, an excursus about damage-plasticity in ductile materials is offered. Single slip mechanism of single crystal plasticity is embedded into the micro-constitutive relations. While the model is limited to incipient plasticity, it captures the formation of shear bands from the localization of slip planes.

  10. ISI law enforcement research

    NASA Astrophysics Data System (ADS)

    LaCoss, Jeff; Granacki, John; Wills, Jack

    1998-12-01

    The Advanced System Division of ISI is engaged in a number of projects focused on using commercial technologies to produce a low-cost system with extensive capability for reconfiguration and experimentation. Low-cost platforms for mobile computing and communications enable experimental approaches to determining requirements for law enforcement and military field applications. Unfortunately, flexible COTS hardware is generally unavailable, forcing experiments to make use of costly special-purpose hardware.

  11. Ethics and Law

    NASA Astrophysics Data System (ADS)

    Vilacoba Ramos, Andrés

    2007-04-01

    Ethics are the set of moral rules that govern human conduct. Hegel, for his part, asserted that ethicity implied the full realization of freedom, as well as the suppression of it as arbitrariness. In this paper, we point out that, through the relation between Law and Ethics, we can discover how high are the Ethics of a society, as well as the adherence of its members to it.

  12. Enforcing pollution control laws

    SciTech Connect

    Russell, C.S.; Harrington, W.; Vaughan, W.J.

    1986-01-01

    The heightened environmental consciousness of the 1970s prompted passage of a multitude of ambitious and unprecedented laws designed to clean up the environment and protect it for future generations. But beyond the mere passing of laws lay the difficult tasks of implementing, monitoring, and enforcing them. The authors of this book describe the current state of air and water pollution monitoring and enforcement activity a decade later, within the context of relevant legal, technological, and statistical developments. They mediate between the concerns of the theoretical literature-where it is generally assumed that violations are discovered and punished-and the real world-where violations are rarely discovered and almost never punished. Monitoring and enforcement procedures to date have been aimed at achieving initial rather than continuing compliance with regulations. The authors contend that it is time for a new approach focusing on the enduring problems of compliance. Economic models are used to show the extent of the difficulties involved in monitoring and enforcing pollution control laws on a continuous basis.

  13. Henry's Law and Noisy Knuckles.

    ERIC Educational Resources Information Center

    Kimbrough, Doris R.

    1999-01-01

    Discusses Henry's Law which describes the relationship between the pressure of gas and the concentration of that gas in a solution. Presents an application of Henry's Law to the cracking of knuckles. (CCM)

  14. Turning around Newton's Second Law

    ERIC Educational Resources Information Center

    Goff, John Eric

    2004-01-01

    Conceptual and quantitative difficulties surrounding Newton's second law often arise among introductory physics students. Simply turning around how one expresses Newton's second law may assist students in their understanding of a deceptively simple-looking equation.

  15. Dynamics and Adaptive Control for Stability Recovery of Damaged Aircraft

    NASA Technical Reports Server (NTRS)

    Nguyen, Nhan; Krishnakumar, Kalmanje; Kaneshige, John; Nespeca, Pascal

    2006-01-01

    This paper presents a recent study of a damaged generic transport model as part of a NASA research project to investigate adaptive control methods for stability recovery of damaged aircraft operating in off-nominal flight conditions under damage and or failures. Aerodynamic modeling of damage effects is performed using an aerodynamic code to assess changes in the stability and control derivatives of a generic transport aircraft. Certain types of damage such as damage to one of the wings or horizontal stabilizers can cause the aircraft to become asymmetric, thus resulting in a coupling between the longitudinal and lateral motions. Flight dynamics for a general asymmetric aircraft is derived to account for changes in the center of gravity that can compromise the stability of the damaged aircraft. An iterative trim analysis for the translational motion is developed to refine the trim procedure by accounting for the effects of the control surface deflection. A hybrid direct-indirect neural network, adaptive flight control is proposed as an adaptive law for stabilizing the rotational motion of the damaged aircraft. The indirect adaptation is designed to estimate the plant dynamics of the damaged aircraft in conjunction with the direct adaptation that computes the control augmentation. Two approaches are presented 1) an adaptive law derived from the Lyapunov stability theory to ensure that the signals are bounded, and 2) a recursive least-square method for parameter identification. A hardware-in-the-loop simulation is conducted and demonstrates the effectiveness of the direct neural network adaptive flight control in the stability recovery of the damaged aircraft. A preliminary simulation of the hybrid adaptive flight control has been performed and initial data have shown the effectiveness of the proposed hybrid approach. Future work will include further investigations and high-fidelity simulations of the proposed hybrid adaptive Bight control approach.

  16. Simulating Evolution

    ERIC Educational Resources Information Center

    Stebbins, Robert C.; Allen, Brockenbrough

    1975-01-01

    Described are simulations that can be used to illustrate evolution by natural selection. Suggestions for simulating phenomena such as adaptive radiation, color match to background and vision of predators are offered. (BR)

  17. Composites Damage Tolerance Workshop

    NASA Technical Reports Server (NTRS)

    Gregg, Wayne

    2006-01-01

    The Composite Damage Tolerance Workshop included participants from NASA, academia, and private industry. The objectives of the workshop were to begin dialogue in order to establish a working group within the Agency, create awareness of damage tolerance requirements for Constellation, and discuss potential composite hardware for the Crew Launch Vehicle (CLV) Upper Stage (US) and Crew Module. It was proposed that a composites damage tolerance working group be created that acts within the framework of the existing NASA Fracture Control Methodology Panel. The working group charter would be to identify damage tolerance gaps and obstacles for implementation of composite structures into manned space flight systems and to develop strategies and recommendations to overcome these obstacles.

  18. Northridge, CA Earthquake Damage

    The person in this image was a USGS employee at the time this was taken. Collection of USGS still images taken after the January 17, 1994 Northridge earthquake highlighting the damage to buildings and infrastructure....

  19. Composite heat damage assessment

    SciTech Connect

    Janke, C.J.; Wachter, E.A.; Philpot, H.E.; Powell, G.L.

    1993-12-31

    The effects of heat damage were determined on the residual mechanical, physical, and chemical properties of IM6/3501-6 laminates, and potential nondestructive techniques to detect and assess material heat damage were evaluated. About one thousand preconditioned specimens were exposed to elevated temperatures, then cooled to room temperature and tested in compression, flexure, interlaminar shear, shore-D hardness, weight loss, and change in thickness. Specimens experienced significant and irreversible reduction in their residual properties when exposed to temperatures exceeding the material upper service temperature of this material (350{degrees}F). The Diffuse Reflectance Infrared Fourier Transform and Laser-Pumped Fluorescence techniques were found to be capable of rapid, in-service, nondestructive detection and quantitation of heat damage in IM6/3501- 6. These techniques also have the potential applicability to detect and assess heat damage effects in other polymer matrix composites.

  20. LSD and Genetic Damage

    ERIC Educational Resources Information Center

    Dishotsky, Norman I.; And Others

    1971-01-01

    Reviews studies of the effects of lysergic acid diethylamide (LSD) on man and other organisms. Concludes that pure LSD injected in moderate doses does not cause chromosome or detectable genetic damage and is not a teratogen or carcinogen. (JM)

  1. Nonlinear damage analysis: Postulate and evaluation

    NASA Technical Reports Server (NTRS)

    Leis, B. N.; Forte, T. P.

    1983-01-01

    The objective of this program is to assess the viability of a damage postulate which asserts that the fatigue resistance curve of a metal is history dependent due to inelastic action. The study focusses on OFE copper because this simple model material accentuates the inelastic action central to the damage postulate. Data relevant to damage evolution and crack initiation are developed via a study of surface topography. The effects of surface layer residual stresses are explored via comparative testing as were the effects in initial prestraining. The results of the study very clearly show the deformation history dependence of the fatigue resistance of OFE copper. Furthermore the concept of deformation history dependence is shown to qualitatively explain the fatigue resistance of all histories considered. Likewise quantitative predictions for block cycle histories are found to accurately track the observed results. In this respect the assertion that damage per cycle for a given level of the damage parameter is deformation history dependent appears to be physically justified.

  2. Punctuated equilibrium and power law in economic dynamics

    NASA Astrophysics Data System (ADS)

    Gupta, Abhijit Kar

    2012-02-01

    This work is primarily based on a recently proposed toy model by Thurner et al. (2010) [3] on Schumpeterian economic dynamics (inspired by the idea of economist Joseph Schumpeter [9]). Interestingly, punctuated equilibrium has been shown to emerge from the dynamics. The punctuated equilibrium and Power law are known to be associated with similar kinds of biologically relevant evolutionary models proposed in the past. The occurrence of the Power law is a signature of Self-Organised Criticality (SOC). In our view, power laws can be obtained by controlling the dynamics through incorporating the idea of feedback into the algorithm in some way. The so-called 'feedback' was achieved by introducing the idea of fitness and selection processes in the biological evolutionary models. Therefore, we examine the possible emergence of a power law by invoking the concepts of 'fitness' and 'selection' in the present model of economic evolution.

  3. Time Dependence of Joy's Law for Emerging Active Regions

    NASA Astrophysics Data System (ADS)

    Chintzoglou, Georgios; Zhang, J.; Liu, Y.

    2013-07-01

    Joy's law governs the tilt of Active Regions (ARs) with respect to their absolute heliographic latitude. Together with Hale's law of hemispheric polarity, it is essential in constraining solar dynamo models. However, previous studies on Joy's law show only a weak positive trend between AR tilt angles and latitudes. In this study, we are focusing on the time dependence of Joy's law, for the cases of emerging ARs of Solar Cycle 24. We selected 40 ARs that emerge on the East hemisphere, effectively maximizing the observing time for each AR. Then, by converting the helioprojective maps into heliographic, we determine the geometrical as well as the magnetic-flux-weighted centroids for each emergence case. That way we are able to track the temporal evolution of their physical properties, including locations, fluxes of positive and negative polarities, as well as the tilt angles of these regions in a continuous manner until emergence stops and the ARs assume their final state.

  4. Law and the Physical Educator.

    ERIC Educational Resources Information Center

    Jansma, Paul; French, Ron

    1982-01-01

    Since federal and state laws directly influence the professional activities of physical educators, it is essential to understand the implications of particular laws and regulations as well as legal processes. Some misconceptions about the law are examined, and techniques by which physical educators can affect educational policy are explored. (JN)

  5. Law-Focused Education: Iowa.

    ERIC Educational Resources Information Center

    University of Northern Iowa, Cedar Falls. Malcolm Price Lab. School.

    This law-focused resource booklet is intended to help secondary level students learn about the civil law portion of Iowa's judicial system. The materials are designed to help students understand how to deal with conflict in a peaceful and orderly manner and how to cope with decision making in personal law situations as related to the family, the…

  6. Practical Law in New Mexico.

    ERIC Educational Resources Information Center

    Smith, Melinda, Ed.

    This book was written for teachers and students as a New Mexico supplement to "Street Law: A Course in Practical Law" (West Publishing Company, 1980), a text used in many high school law classes. The book may also be used as a teacher and student resource for civics, government, and other courses in the high school curriculum, or lay people might…

  7. Immigration Law & the American Dream.

    ERIC Educational Resources Information Center

    Parrini, Michelle, Ed.; Parins, Claire, Ed.; Kittlaus, Jennifer, Ed.; Bliss, Pam, Ed.

    2001-01-01

    This magazine is designed to help high school teachers of civics, government, history, law, and law-related education program developers educate students about legal issues. This issue focuses on immigration law and the American Dream. It includes 11 articles: (1) "U.S. Immigration Policy and Globalization" (P. Martin; S. Martin) explains how the…

  8. Freedom under Law. Revised edition.

    ERIC Educational Resources Information Center

    Denver Public Schools, CO.

    This pamphlet identifies and explains Colorado laws as they apply to juveniles and adults. The handbook was specifically developed to help teenagers know how the laws protect them and how they are expected to comply with them. Two short sections discuss the necessity of having laws and give definitions of 12 legal terms such as felony and petty

  9. Freedom under Law. Revised edition.

    ERIC Educational Resources Information Center

    Denver Public Schools, CO.

    This pamphlet identifies and explains Colorado laws as they apply to juveniles and adults. The handbook was specifically developed to help teenagers know how the laws protect them and how they are expected to comply with them. Two short sections discuss the necessity of having laws and give definitions of 12 legal terms such as felony and petty…

  10. Tax Breaks for Law Students.

    ERIC Educational Resources Information Center

    Button, Alan L.

    1981-01-01

    A guide to federal income tax law as it affects law students is presented. Some costs that may constitute valuable above-the-line deductions are identified: moving expenses, educational expenses, job-seeking expenses, and income averaging. Available from Washington and Lee University School of Law, Lexington, VA 24450, $5.50 sc) (MLW)

  11. Immigration Law & the American Dream.

    ERIC Educational Resources Information Center

    Parrini, Michelle, Ed.; Parins, Claire, Ed.; Kittlaus, Jennifer, Ed.; Bliss, Pam, Ed.

    2001-01-01

    This magazine is designed to help high school teachers of civics, government, history, law, and law-related education program developers educate students about legal issues. This issue focuses on immigration law and the American Dream. It includes 11 articles: (1) "U.S. Immigration Policy and Globalization" (P. Martin; S. Martin) explains how the

  12. Higher Education and the Law.

    ERIC Educational Resources Information Center

    Edwards, Harry T.; Nordin, Virginia Davis

    The proliferation of laws, regulations, and judicial opinions affecting higher education and the nature of the impact of these laws on the academic community are examined. Designed for use by both students and practitioners, the book employs the "case method" design based on the belief that law cases furnish the best sources for study and review…

  13. General laws of evolution and the problem of extraterrestrial civilizations

    NASA Astrophysics Data System (ADS)

    Kaziutinskii, V. V.

    The paper examines the possible relationship betweeen the integral properties of the evolving universe (i.e., the Metagalaxy) and the appearance of conditions making possible the existence of mankind. The possible existence of extraterrestial civilizations is discussed in the light of the anthropic principle.

  14. Simple model of self-organized biological evolution

    SciTech Connect

    de Boer, J.; Derrida, B.; Flyvbjerg, H.; Jackson, A.D.; Wettig, T. The Isaac Newton Institute for Mathematical Sciences, 20 Clarkson Road, Cambridge, CB4 0EH Laboratoire de Physique Statistique, Ecole Normale Superieure, 24 rue Lhomond, F-75005 Paris Service de Physique Theorique, Centre de Etudes Nucleaires de Saclay, F-91191, Gif-Sur-Yvette CONNECT, The Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen )

    1994-08-08

    We give an exact solution of a recently proposed self-organized critical model of biological evolution. We show that the model has a power law distribution of durations of coevolutionary avalanches'' with a mean field exponent 3/2. We also calculate analytically the finite size effects which cut off this power law at times of the order of the system size.

  15. Chemical Laws, Idealization and Approximation

    NASA Astrophysics Data System (ADS)

    Tobin, Emma

    2013-07-01

    This paper examines the notion of laws in chemistry. Vihalemm ( Found Chem 5(1):7-22, 2003) argues that the laws of chemistry are fundamentally the same as the laws of physics they are all ceteris paribus laws which are true "in ideal conditions". In contrast, Scerri (2000) contends that the laws of chemistry are fundamentally different to the laws of physics, because they involve approximations. Christie ( Stud Hist Philos Sci 25:613-629, 1994) and Christie and Christie ( Of minds and molecules. Oxford University Press, New York, pp. 34-50, 2000) agree that the laws of chemistry are operationally different to the laws of physics, but claim that the distinction between exact and approximate laws is too simplistic to taxonomise them. Approximations in chemistry involve diverse kinds of activity and often what counts as a scientific law in chemistry is dictated by the context of its use in scientific practice. This paper addresses the question of what makes chemical laws distinctive independently of the separate question as to how they are related to the laws of physics. From an analysis of some candidate ceteris paribus laws in chemistry, this paper argues that there are two distinct kinds of ceteris paribus laws in chemistry; idealized and approximate chemical laws. Thus, while Christie ( Stud Hist Philos Sci 25:613-629, 1994) and Christie and Christie ( Of minds and molecules. Oxford University Press, New York, pp. 34--50, 2000) are correct to point out that the candidate generalisations in chemistry are diverse and heterogeneous, a distinction between idealizations and approximations can nevertheless be used to successfully taxonomise them.

  16. Kinetics of wealth and the Pareto law

    NASA Astrophysics Data System (ADS)

    Boghosian, Bruce M.

    2014-04-01

    An important class of economic models involve agents whose wealth changes due to transactions with other agents. Several authors have pointed out an analogy with kinetic theory, which describes molecules whose momentum and energy change due to interactions with other molecules. We pursue this analogy and derive a Boltzmann equation for the time evolution of the wealth distribution of a population of agents for the so-called Yard-Sale Model of wealth exchange. We examine the solutions to this equation by a combination of analytical and numerical methods and investigate its long-time limit. We study an important limit of this equation for small transaction sizes and derive a partial integrodifferential equation governing the evolution of the wealth distribution in a closed economy. We then describe how this model can be extended to include features such as inflation, production, and taxation. In particular, we show that the model with taxation exhibits the basic features of the Pareto law, namely, a lower cutoff to the wealth density at small values of wealth, and approximate power-law behavior at large values of wealth.

  17. Kinetics of wealth and the Pareto law.

    PubMed

    Boghosian, Bruce M

    2014-04-01

    An important class of economic models involve agents whose wealth changes due to transactions with other agents. Several authors have pointed out an analogy with kinetic theory, which describes molecules whose momentum and energy change due to interactions with other molecules. We pursue this analogy and derive a Boltzmann equation for the time evolution of the wealth distribution of a population of agents for the so-called Yard-Sale Model of wealth exchange. We examine the solutions to this equation by a combination of analytical and numerical methods and investigate its long-time limit. We study an important limit of this equation for small transaction sizes and derive a partial integrodifferential equation governing the evolution of the wealth distribution in a closed economy. We then describe how this model can be extended to include features such as inflation, production, and taxation. In particular, we show that the model with taxation exhibits the basic features of the Pareto law, namely, a lower cutoff to the wealth density at small values of wealth, and approximate power-law behavior at large values of wealth. PMID:24827290

  18. Damage Tolerance and Durability of Material Systems

    NASA Astrophysics Data System (ADS)

    Reifsnider, Kenneth L.; Case, Scott W.

    2002-04-01

    A daring, original approach to understanding and predicting the mechanical behavior of materials "Damage is an abstraction . . . Strength is an observable, an independent variable that can be measured, with clear and familiar engineering definitions." -from the Preface to Damage Tolerance and Durability of Material Systems Long-term behavior is one of the most challenging and important aspects of material engineering. There is a great need for a useful conceptual or operational framework for measuring long-term behavior. As much a revolution in philosophy as an engineering text, Damage Tolerance and Durability of Material Systems postulates a new mechanistic philosophy and methodology for predicting the remaining strength and life of engineering material. This philosophy associates the local physical changes in material states and stress states caused by time-variable applied environments with global properties and performance. There are three fundamental issues associated with the mechanical behavior of engineering materials and structures: their stiffness, strength, and life. Treating these issues from the standpoint of technical difficulty, time, and cost for characterization, and relationship to safety, reliability, liability, and economy, the authors explore such topics as: * Damage tolerance and failure modes * Factors that determine composite strength * Micromechanical models of composite stiffness and strength * Stiffness evolution * Strength evolution during damage accumulation * Non-uniform stress states * Lifetime prediction With a robust selection of example applications and case studies, this book takes a step toward the fulfillment of a vision of a future in which the prediction of physical properties from first principles will make possible the creation and application of new materials and material systems at a remarkable cost savings.

  19. Thresholded Power law Size Distributions of Instabilities in Astrophysics

    NASA Astrophysics Data System (ADS)

    Aschwanden, Markus J.

    2015-11-01

    Power-law-like size distributions are ubiquitous in astrophysical instabilities. There are at least four natural effects that cause deviations from ideal power law size distributions, which we model here in a generalized way: (1) a physical threshold of an instability; (2) incomplete sampling of the smallest events below a threshold x0; (3) contamination by an event-unrelated background xb; and (4) truncation effects at the largest events due to a finite system size. These effects can be modeled in the simplest terms with a “thresholded power law” distribution function (also called generalized Pareto [type II] or Lomax distribution), N(x){dx}\\propto {(x+{x}0)}-a{dx}, where x0 > 0 is positive for a threshold effect, while x0 < 0 is negative for background contamination. We analytically derive the functional shape of this thresholded power law distribution function from an exponential growth evolution model, which produces avalanches only when a disturbance exceeds a critical threshold x0. We apply the thresholded power law distribution function to terrestrial, solar (HXRBS, BATSE, RHESSI), and stellar flare (Kepler) data sets. We find that the thresholded power law model provides an adequate fit to most of the observed data. Major advantages of this model are the automated choice of the power law fitting range, diagnostics of background contamination, physical instability thresholds, instrumental detection thresholds, and finite system size limits. When testing self-organized criticality models that predict ideal power laws, we suggest including these natural truncation effects.

  20. Initiation and Evolution of Matrix Cracking in Non-Symmetric Laminates under in-Plane and Flexural Loading

    NASA Astrophysics Data System (ADS)

    Adumitroaie, Adi

    A constitutive model of progressive matrix cracking in fibers reinforced laminated composite is developed for the case of both membrane and flexural deformation. The progressive damage model makes use of the following key ingredients i) an appropriate material model for calculating the reduced thermo-elastic properties of the laminate containing individual plies affected by matrix cracking, ii) an energy based damage evolution criterion inspired by Fracture Mechanics, iii) an homogenization technique inspired by Continuum Damage Mechanics, iv) an iterative procedure in order to detect the conditions for damage growth in individual plies of the laminate, and to increase the damage level when the conditions are met, and v) the Classical Laminate Theory in order to describe the overall membrane and flexural deformation of the laminated composite. These elements are integrated into a new progressive damage model, where both the degraded mechanical properties of the laminate for given levels of matrix cracking in individual plies, and the matrix cracking process (both onset and progression) under applied loading are regarded. Crack densities in individual plies of the laminates are the damage state variables of the model. This formulation is unlike the progressive damage models for laminated composites implemented in most of the FEA commercial packages, where softening laws are implemented in order to describe the stiffness reduction and the damage evolution. By using the ply crack densities as state variables the model is able to predict and to keep track of the crack density in individual plies during the loading history, which can be of interest in application where the permeability of the laminate is a limiting design factor. One example of this kind of application can be pressure vessels containing fluids or gases. Thermal residual stresses are taken into account in the present analytical model, which can extend the predictive capabilities of the model to applications in the range of cryogenic temperatures. The process of matrix cracking under I, II, or mixed I-II modes conditions are included in the present model. The loading case can be in-plane, flexural or combination of the two. There is no limitation on the configuration of the laminate or on the number of the cracking plies, as it is the case of the most models available in the literature, where only symmetric stacking sequences are addressed. The analytical model is validated against available experimental data for the case of both membrane and flexural loading.

  1. Discussion on ``Frontiers of the Second Law''

    NASA Astrophysics Data System (ADS)

    Lloyd, Seth; Bejan, Adrian; Bennett, Charles; Beretta, Gian Paolo; Butler, Howard; Gordon, Lyndsay; Grmela, Miroslav; Gyftopoulos, Elias P.; Hatsopoulos, George N.; Jou, David; Kjelstrup, Signe; Lior, Noam; Miller, Sam; Rubi, Miguel; Schneider, Eric D.; Sekulic, Dusan P.; Zhang, Zhuomin

    2008-08-01

    This article reports an open discussion that took place during the Keenan Symposium "Meeting the Entropy Challenge" (held in Cambridge, Massachusetts, on October 4, 2007) following the short presentationseach reported as a separate article in the present volumeby Adrian Bejan, Bjarne Andresen, Miguel Rubi, Signe Kjelstrup, David Jou, Miroslav Grmela, Lyndsay Gordon, and Eric Schneider. All panelists and the audience were asked to address the following questions Is the second law relevant when we trap single ions, prepare, manipulate and measure single photons, excite single atoms, induce spin echoes, measure quantum entanglement? Is it possible or impossible to build Maxwell demons that beat the second law by exploiting fluctuations? Is the maximum entropy generation principle capable of unifying nonequilibrium molecular dynamics, chemical kinetics, nonlocal and nonequilibrium rheology, biological systems, natural structures, and cosmological evolution? Research in quantum computation and quantum information has raised many fundamental questions about the foundations of quantum theory. Are any of these questions related to the second law?

  2. Assessing Tropical Cyclone Damage

    NASA Astrophysics Data System (ADS)

    Done, J.; Czajkowski, J.

    2012-12-01

    Landfalling tropical cyclones impact large coastal and inland areas causing direct damage due to winds, storm-surge flooding, tornadoes, and precipitation; as well as causing substantial indirect damage such as electrical outages and business interruption. The likely climate change impact of increased tropical cyclone intensity, combined with increases in exposure, bring the possibility of increased damage in the future. A considerable amount of research has focused on modeling economic damage due to tropical cyclones, and a series of indices have been developed to assess damages under climate change. We highlight a number of ways this research can be improved through a series of case study analyses. First, historical loss estimates are revisited to properly account for; time, impacted regions, the source of damage by type, and whether the damage was direct/indirect and insured/uninsured. Second, the drivers of loss from both the socio-economic and physical side are examined. A case is made to move beyond the use of maximum wind speed to more stable metrics and the use of other characteristics of the wind field such as direction, degree of gustiness, and duration is explored. A novel approach presented here is the potential to model losses directly as a function of climate variables such as sea surface temperature, greenhouse gases, and aerosols. This work is the first stage in the development of a tropical cyclone loss model to enable projections of losses under scenarios of both socio-economic change (such as population migration or altered policy) and physical change (such as shifts in tropical cyclone activity one from basin to another or within the same basin).

  3. [Environmental damage assessment: international regulations and revelation to China].

    PubMed

    Zhang, Hong-zhen; Cao, Dong; Yu, Fang; Wang, Jin-nan; Qi, Ji; Jia, Qian; Zhang, Tian-zhu; Luo, Yong-ming

    2013-05-01

    As the whole society gradually realizes the scarcity of nature resources and environmental value, countries all over the world have evolved and improved the system of environmental damage assessment through the practices of pollution prevention and ecological environmental protection. On one hand, in the research prospective, the practices of environmental damage assessment brought new challenges to environmental law, environmental economics, environmental science, environmental engineering, etc. On the other hand, they constantly promoted and developed relevant laws and regulations, techniques, working mechanism, and guidelines on procedure in practice. On the hasis of comparison and analysis of international practices and experiences from US, EU, and Japan, etc., this article identified relevant concepts, content, and scope of environmental damage assessment, and presented its scientific positioning and development direction. At present, both theory and practice of environmental damage assessment in China are in their infancy period. Considering current environmental situation and socioeconomic development features of China, learning international practices and experiences and raising the orientation of environmental damage assessment have great meaning in exploring the suitable environmental damage assessment system. PMID:23914513

  4. The laws of violence.

    PubMed

    Bache, J

    2000-11-01

    Working in an accident and emergency (A&E) department inevitably involves dealing with the consequences of violence, and a knowledge of the laws of violence is a useful adjunct to the clinical practice of A&E medicine. The police and the Crown Prosecution Service decide whether or not to charge a suspect, and which charge is appropriate. All criminal offences are initially considered in the magistrates' court but the more serious offences may be committed to crown court. Specific offences include common assault, actual bodily harm, grievous bodily harm, and grievous bodily harm with intent. If the defendant is found guilty, an appropriate sentence is imposed. PMID:11104238

  5. Epilepsy and law.

    PubMed

    Beran, Roy G

    2008-05-01

    Epilepsy can define who one is rather than the diagnosis one has. It may be considered under the rubric of disability with legislative protection against discrimination. Those seeking remedy should investigate alternative dispute resolution in preference to litigation. Many areas of the life of a person with epilepsy deserve examination when considering epilepsy and law. Just some of these include: duty of care; informed consent; driving; research; social interactions; insurance; recreational pursuits; employment; and privacy. This article examines the legal implications and ramifications of these selected topics, acknowledging that the limited scope of the article has only exposed the tip of the iceberg to encourage further exploration. PMID:18234559

  6. Environmental law institute

    SciTech Connect

    Futrell, J.W.

    1993-10-01

    Congress and the Clinton Administration must consider reauthorizing some of the country's most important environmental statutes during a time of increasing environmental concern and decreasing financial resources. The debate over the U.S. environmental direction is fierce; yet if history is any guide, the result of the commotion will be better policy. The constant tugging and pulling may slog the law-making process, but resulting policy is often much better because of it. Fundamental policy issues continue to be as pertinent today as they were in the 1970s.

  7. On integrable conservation laws

    PubMed Central

    Arsie, Alessandro; Lorenzoni, Paolo; Moro, Antonio

    2015-01-01

    We study normal forms of scalar integrable dispersive (not necessarily Hamiltonian) conservation laws, via the Dubrovin–Zhang perturbative scheme. Our computations support the conjecture that such normal forms are parametrized by infinitely many arbitrary functions that can be identified with the coefficients of the quasi-linear part of the equation. Moreover, in general, we conjecture that two scalar integrable evolutionary partial differential equations having the same quasi-linear part are Miura equivalent. This conjecture is also consistent with the tensorial behaviour of these coefficients under general Miura transformations. PMID:25568614

  8. Simulation of Self-Repair Process of Steels Damaged by Creep

    NASA Astrophysics Data System (ADS)

    Toi, Yutaka; Hirose, Satoshi

    The continuum damage mechanics is extended to cover the self-repair process as well as the damage process. The repair variable and its evolution equation are newly introduced to consider the repair process. In the constitutive modeling, the equation of creep based on kinematic/isotropic hardening theory is extended to take the effect of damage into account. The evolution equation of a repair variable is proposed, based on Dyson's equation of creep cavity growth. The validity of the proposed modeling is illustrated through the simulations for the self-repair process of two kinds of steels damaged by creep.

  9. Infrared thermography of damage evaluation in leather products

    NASA Astrophysics Data System (ADS)

    Luong, Minh Phong

    1999-05-01

    The paper aims to illustrate three advantages of infrared thermography as a non-destructive, non-contact and real-time technique (a) to observe the progressive damage processes and failure mechanisms of leather, (b) to detect the occurrence of intrinsic dissipation localization, and (b) to evaluate a threshold of acceptable damage. The parameter, investigated in this paper, is the heat generation due to intrinsic dissipation caused by anelasticity and/or inelasticity of leather. It readily describes the damage location and the failure evolution of leather for sport foot-wear.

  10. The constitutive representation of high-temperature creep damage

    NASA Technical Reports Server (NTRS)

    Chan, K. S.

    1988-01-01

    The elastic-viscoplastic constitutive equations of Bodner-Partom were applied to modeling creep damage in a high temperature Ni-alloy, B1900 + Hf. Both tertiary creep in bulk materials and creep crack growth in flawed materials were considered. In the latter case, the energy rate line integral was used for characterizing the crack driving force, and the rate of crack extension was computed using a local damage formulation that assumed fracture was controlled by cavitation occurring within the crack-tip process zone. The results of this investigation were used to assess the evolution equation for isotropic damage utilized in the Bodner-Partom constitutive equations.

  11. Repairing damaged structures

    SciTech Connect

    Perano, A.C.

    1980-08-01

    While Grace Platform was being installed, damage was sustained to jacket members, varying from metal rubbing to denting and puncturing by a falling section of pile follower. Because the 12-legged jacket is in a water depth in excess of 300 ft it was necessary to use a remote controlled vehicle in order to establish a preliminary damage report to determine whether the structural integrity of the jacket with the damaged braces required repair, reinforcing, removal, or just to be left as they were. From information gathered on videotapes, it was possible to direct the divers to all questionable areas and to study each in detail. From the sketches, photographs and accompanying report, there was sufficient information and data for the designers of the platform to conduct an investigation and analysis of the areas in question. The analysis was performed using storm and seismic loading conditions. The results obtained determined damaged members. All parties concerned with the damage investigation agreed upon which structures needed to be repaired and under what conditions the repairs would take place.

  12. Reducing Radiation Damage

    SciTech Connect

    Blankenbecler, Richard

    2006-06-05

    This talk describes the use of a modified treatment sequence, i.e., radiation dose, geometry, dwell time, etc., to mitigate some of the deleterious effects of cancer radiotherapy by utilizing natural cell repair processes. If bad side effects can be reduced, a more aggressive therapy can be put into place. Cells contain many mechanisms that repair damage of various types. If the damage can not be repaired, cells will undergo apoptosis (cell death). Data will be reviewed that support the fact that a small dose of radiation will activate damage repair genes within a cell. Once the mechanisms are fully active, they will efficiently repair the severe damage from a much larger radiation dose. The data ranges from experiments on specific cell cultures using microarray (gene chip) techniques to experiments on complete organisms. The suggested effect and treatment is consistent with the assumption that all radiation is harmful, no matter how small the dose. Nevertheless, the harm can be reduced. These mechanisms need to be further studied and characterized. In particular, their time dependence needs to be understood before the proposed treatment can be optimized. Under certain situations it is also possible that the deleterious effects of chemotherapy can be mitigated and the damage to radiation workers can be reduced.

  13. [Common law, civil law: thinking about the tools of the judge in bioethics].

    PubMed

    Baudouin, Jean-Louis

    2006-01-01

    Civilian and common law judges differ substantially in their approach to the resolution of issues concerning bioethics and health sciences. Whereas the civilian judge will first take into account the legislative source, his common law counterpart will most probably first look at judicial precedents for guidance. In both systems, however, the legislative drafting technique differs substantially and has a direct impact on judicial interpretation of the law. Both systems also differ in the way that judicial decisions are drafted and rendered. In the common law tradition, judges draft their own opinion, leaving the possibility of dissent which, in turn, helps to better illustrate contentious issues and may have an influence on social awareness of difficult problems. Finally, in bioethics, legislation should be preferred if only for a question of social legitimacy, since decisions are then taken by elected representatives. However, this type of legislation should be subject to periodical review to better adapt its rules to the evolution of science and society. PMID:17902324

  14. PSYCHIATRY AND THE LAW

    PubMed Central

    Zeifert, Mark

    1957-01-01

    In Rex vs. Arnold (1724) it was held that to avail himself of the defense of insanity “a man must be totally deprived of his understanding and memory, so as not to know what he is doing, no more than an infant, a brute, or a wild beast.” Although there has been some modification of this formula in most jurisdictions, the courts still operate under the McNaghten Rule (1843) which is no more logical and actually is more difficult to apply. That such a situation exists in 1956 is a reflection on the indifference of society—and particularly the courts which it elects—as well as on the failure of modern psychiatry to communicate its viewpoint to society. If we are to correct the sad formulae of the “right and wrong” and “policeman at the elbow” tests, we must have more study and better methods of communication in this area. A similar state of confusion exists in the methods of commitment of mentally ill people to psychiatric hospitals. The methods prescribed by law are archaic and cruel—and again reflect the failure of modern psychiatry to communicate its understanding to the legislatures and courts. There are many other areas of conflict between law (which looks to the past for its insights) and psychiatry (which seeks for its concepts in the current scientific advances). PMID:13383383

  15. Medicine and the law.

    PubMed

    Golman, S J

    1975-02-01

    1. Public and private benefits offering security for life if the need is of sufficient magnitude inhibits optimum restoration of the patient. 2. The physician frequently does not recognise nor is concerned with the premorbid attitude, goals or life-style of the patient and does not effectively deal with the future temporal needs of the patient, thereby contributing to less than satisfactory levels of restoration. 3. The law and its objectives as practised by the lawyers often develop into an intense adversary posture, threatening the security of the patient and jeopardising a satisfactory level of restoration. 4. Administration of the law by judicial and quasi-judicial judges and juries is manipulated to give the highest award possible, therefore the plaintiff will not be restored to the satisfactory level of which he is capable. 5. There is hostility and little communication between physician and lawyer again contributing to the patient's failure in restoration. 6. The adversary system is accused of creating conditions contributing to unsatisfactory restoration but can be utilised as a motivational force with innovative and creative thinking on the part of the professions to meet the real needs and goals for security of the patient and motivate his restoration. 7. Communication and role-playing exchange between the professions and the patient as his condition will require, promote a successful and acceptable restoration. 8. The counsel involved develop the process for prompt financial disposition without involving the patient in the adversary process or in trial. PMID:1121408

  16. Fault tolerant control laws

    NASA Technical Reports Server (NTRS)

    Ly, U. L.; Ho, J. K.

    1986-01-01

    A systematic procedure for the synthesis of fault tolerant control laws to actuator failure has been presented. Two design methods were used to synthesize fault tolerant controllers: the conventional LQ design method and a direct feedback controller design method SANDY. The latter method is used primarily to streamline the full-state Q feedback design into a practical implementable output feedback controller structure. To achieve robustness to control actuator failure, the redundant surfaces are properly balanced according to their control effectiveness. A simple gain schedule based on the landing gear up/down logic involving only three gains was developed to handle three design flight conditions: Mach .25 and Mach .60 at 5000 ft and Mach .90 at 20,000 ft. The fault tolerant control law developed in this study provides good stability augmentation and performance for the relaxed static stability aircraft. The augmented aircraft responses are found to be invariant to the presence of a failure. Furthermore, single-loop stability margins of +6 dB in gain and +30 deg in phase were achieved along with -40 dB/decade rolloff at high frequency.

  17. Integrable viscous conservation laws

    NASA Astrophysics Data System (ADS)

    Arsie, Alessandro; Lorenzoni, Paolo; Moro, Antonio

    2015-06-01

    We propose an extension of the Dubrovin-Zhang perturbative approach to the study of normal forms for non-Hamiltonian integrable scalar conservation laws. The explicit computation of the first few corrections leads to the conjecture that such normal forms are parameterized by one single functional parameter, named the viscous central invariant. A constant valued viscous central invariant corresponds to the well-known Burgers hierarchy. The case of a linear viscous central invariant provides a viscous analog of the Camassa-Holm equation, that formerly appeared as a reduction of two-component Hamiltonian integrable systems. We write explicitly the negative and positive hierarchy associated with this equation and prove the integrability showing that they can be mapped respectively into the heat hierarchy and its negative counterpart, named the Klein-Gordon hierarchy. A local well-posedness theorem for periodic initial data is also proven. We show how transport equations can be used to effectively construct asymptotic solutions via an extension of the quasi-Miura map that preserves the initial datum. The method is alternative to the method of the string equation for Hamiltonian conservation laws and naturally extends to the viscous case. Using these tools we derive the viscous analog of the Painlevé I2 equation that describes the universal behaviour of the solution at the critical point of gradient catastrophe.

  18. A scaling law of radial gas distribution in disk galaxies

    NASA Technical Reports Server (NTRS)

    Wang, Zhong

    1990-01-01

    Based on the idea that local conditions within a galactic disk largely determine the region's evolution time scale, researchers built a theoretical model to take into account molecular cloud and star formations in the disk evolution process. Despite some variations that may be caused by spiral arms and central bulge masses, they found that many late-type galaxies show consistency with the model in their radial atomic and molecular gas profiles. In particular, researchers propose that a scaling law be used to generalize the gas distribution characteristics. This scaling law may be useful in helping to understand the observed gas contents in many galaxies. Their model assumes an exponential mass distribution with disk radius. Most of the mass are in atomic gas state at the beginning of the evolution. Molecular clouds form through a modified Schmidt Law which takes into account gravitational instabilities in a possible three-phase structure of diffuse interstellar medium (McKee and Ostriker, 1977; Balbus and Cowie, 1985); whereas star formation proceeds presumably unaffected by the environmental conditions outside of molecular clouds (Young, 1987). In such a model both atomic and molecular gas profiles in a typical galactic disk (as a result of the evolution) can be fitted simultaneously by adjusting the efficiency constants. Galaxies of different sizes and masses, on the other hand, can be compared with the model by simply scaling their characteristic length scales and shifting their radial ranges to match the assumed disk total mass profile sigma tot(r).

  19. Crumpling Damaged Graphene

    PubMed Central

    Giordanelli, I.; Mendoza, M.; Andrade Jr., J. S.; Gomes, M. A. F.; Herrmann, H. J.

    2016-01-01

    Through molecular mechanics we find that non-covalent interactions modify the fractality of crumpled damaged graphene. Pristine graphene membranes are damaged by adding random vacancies and carbon-hydrogen bonds. Crumpled membranes exhibit a fractal dimension of 2.71 ± 0.02 when all interactions between carbon atoms are considered, and 2.30 ± 0.05 when non-covalent interactions are suppressed. The transition between these two values, obtained by switching on/off the non-covalent interactions of equilibrium configurations, is shown to be reversible and independent on thermalisation. In order to explain this transition, we propose a theoretical model that is compatible with our numerical findings. Finally, we also compare damaged graphene membranes with other crumpled structures, as for instance polymerised membranes and paper sheets, that share similar scaling properties. PMID:27173442

  20. Damage Tolerance Assessment Branch

    NASA Technical Reports Server (NTRS)

    Walker, James L.

    2013-01-01

    The Damage Tolerance Assessment Branch evaluates the ability of a structure to perform reliably throughout its service life in the presence of a defect, crack, or other form of damage. Such assessment is fundamental to the use of structural materials and requires an integral blend of materials engineering, fracture testing and analysis, and nondestructive evaluation. The vision of the Branch is to increase the safety of manned space flight by improving the fracture control and the associated nondestructive evaluation processes through development and application of standards, guidelines, advanced test and analytical methods. The Branch also strives to assist and solve non-aerospace related NDE and damage tolerance problems, providing consultation, prototyping and inspection services.