Rigid polyurethane foams are used for supports and as encapsulants for electronic assemblies in almost all weapon systems. Mechanical properties (storage, loss, rubbery, and glassy moduli) of three foams are being evaluated; the test scheme is illustrated. Aging tests are also being run on the long-term performance of foams being used in the Russian Fissile Material Container; ...
Energy Citations Database
We have investigated strain-accelerated dynamics of soft glasses theoretically and experimentally. Mechanical rheology measurements performed on a variety of systems reveal evidence for the speeding-up of relaxation at modest shear strains in both step and oscillatory shear flows. Using the soft glassy rheology (SGR) model framework, ...
NASA Astrophysics Data System (ADS)
We present in this Rapid Communication experimental evidence of an acceleration of the zenithal easy-axis dynamics of a nematic liquid crystal (NLC) with the age of a NLC-polymer layer. The comparison with other hard alignment layers strongly indicates that the polymer softness and its ability to reorient in the nematic ordering field is at the origin of ...
PubMed
... Title : Glassy Metals II. Atomic Structure and Dynamics, Electronic Structure, Magnetic Properties,. Descriptive Note : Technical Book,. ...
DTIC Science & Technology
The dynamic properties of plastic crystalline mixed adamantane's derivatives namely cyanoadamantane (75%) and chloroadamantane (25%) were investigated by dielectric and nuclear magnetic resonance (NMR) spectroscopy, covering a spectral range of 12 decades in the temperature range 110-420 K. Phase transformations were studied and dynamical parameters of the ...
Polymer membranes are widely used as barrier or gas/vapors separation materials. Recent experiments have demonstrated that the barrier properties of the polymer nanocomposites (PNC) dramatically different from pure polymer. Usually such properties are quantified by the permeability P of the material to a penetrant which consists of two contributions: the penetrant solubility S and diffusivity D: ...
The influence of the thickness of space lattice of epoxide resin ED-5 in the glassy state on the dynamic modulus of elasticity is investigated. It is shown that variation of the dynamic modulus of elasticity has an extreme nature, and a hypothesis is prop...
National Technical Information Service (NTIS)
... Accelerators and Colliders; Beam Dynamics; Applications and New Methods of Acceleration; New Methods; Linear Accelerators and Pulsed Power ...
... Descriptors : *ACCELEROMETERS, *LINEAR ACCELERATORS, USSR, DYNAMICS, IMPACT SHOCK, TRANSLATIONS, ACCELERATION ...
This report contains lecture notes on beam dynamics and acceleration concepts in particle accelerators. (LSP)
... joint planning, national and international politics ... Beam Dynamics; Accelerator Technology I ... Descriptors : *PARTICLE ACCELERATORS, SYMPOSIA ...
... Onset of 3D network � Vitrification � Glassy behavior 1 2 3 4 Page 28. Vitrification � T g = T g (α) � T large reduction of resin free volume ...
The anomalous dependence of the dynamic modulus of elasticity /804 ... dynamic modulus of elasticity on the degree'of cross linkage on ...
NASA Website
... Title : Molecular Dynamics Simulation of Atactic Poly(Propylene) Structural Differences between the Liquid and Glassy State. ...
... Abstract : The effect of large deformation on the dynamic properties of epoxy resin 826 under elongational creep were studied in the glassy state ...
The main purpose of this work is to investigate the glassy behavior of microemulsions and block copolymers. The origin of glassy behavior in microemulsions and block copolymers is frustration due to a competition between short-range interaction and long r...
... Accession Number : ADA101766. Title : Preliminary Study of the Effects of Prolonged Acceleration on Spinal Dynamics of Baboons. 1. Acceleration. ...
... conducted on accelerator facilities, involving zero ... of similar exposures on accelerators. ... IMPACT ACCELERATION, EXPERIMENTAL DATA, HIGH ...
Page 1. Acceleration Properties of Planar Manipulators ... Acceleration Properties of Planar Manipulators from a Dynamic Standpoint 12. ...
The coupling between electron transfer and protein dynamics has been investigated in reaction centers (RCs) from the wild type (wt) and the carotenoid-less strain R26 of the photosynthetic bacterium Rhodobacter sphaeroides. Recombination kinetics between the primary photoreduced quinone acceptor (QA-) and photoxidized donor (P+) have been analyzed at room temperature in RCs ...
... ADD422981. Title : On the Use of Acceleration Waves to Characterize the Dynamic Response of Nonlinear Viscoelastic Materials,. ...
... HUMAN TOLERANCE TO ACCELERATION Prepared under Contract No. ... IN THE ANALYSIS OF HUMAN TOLERANCE TO ACCELERATION ...
Self-dynamics of water molecules has been studied in hydrated tricalcium silicate as functions of temperature, aging, and in the presence of an additive. A dynamical model taking into account the existence of ``immobile water'' and ``glassy water'' has been used to analyze quasielastic neutron spectrometer spectra. We deduced the ...
The process of attachment of a deformable polystyrene colloidal particle to a planar substrate shows features of slow relaxation and aging, typically observed in many-body disordered and glassy systems. This slow dynamics is attributed to the presence of polymeric tethers constituting a few internal degrees of freedom. The effects of these few degrees of ...
... operational warfare, joint planning, national and international ... of a gas gun accelerator for dynamic warhead tests in the Laboratory for Ballistic ...
... Descriptors : *ACCELERATION, *FINITE ELEMENT ANALYSIS, *SHELTERS, *DYNAMIC LOADS, STRESSES, MATHEMATICAL MODELS, MASS ...
... Accession Number : ADA420006. Title : An Analysis of Airship Acceleration Dynamics for Airborne Gravimetry. Descriptive Note : Rept. ...
From numerical minimization of a model free-energy functional for a system of hard spheres, we show that the width of the local peaks of the time-averaged density field at a glassy free-energy minimum exhibits large spatial variation, similar to that of the "local Debye-Waller factor" in simulations of dynamical heterogeneity. Molecular ...
... The DSM does not describe the glassy regime in polymer dynamics and, therefore, the experimental value of G0 N (apparent plateau modulus) is ...
We discuss use of the generalized NK model to examine evolutionary dynamics within the immune system. We describe how randomness and diversity play key roles in the immune response and how their effects are captured by this hierarchical spin glass model. We discuss analytical aspects of the model as well as practical applications to design of the annual influenza vaccine. We ...
The problem of dynamics optimization for charged particle beams in RFQ accelerators is discussed in this article. The problems of the optimization of particle capture into the acceleration mode are analyzed. Accelerators with low injection energies are considered.
We study the dynamics of a one-dimensional fluid of orientable hard rectangles with a non-coarse-grained microscopic mechanism of facilitation. The length occupied by a rectangle depends on its orientation, which is a discrete variable coupled to an external field. The equilibrium properties of our model are essentially those of the Tonks gas, but at high densities the ...
The longitudinal particle dynamics in a linear accelerator in the acceleration regime of two waves with multiple frequency without regard for space charge is considered. The accelerating structure of a cavity resonator with 100 MeV drift tubes of is chose...
Modern graphics processing units (GPUs) provide impressive computing resources, which can be accessed conveniently through the CUDA programming interface. We describe how GPUs can be used to considerably speed up molecular dynamics (MD) simulations for system sizes ranging up to about 1 million particles. Particular emphasis is put on the numerical long-time stability in terms ...
This paper investigates the dynamics and acceleration levels of a new tethered system for micro- and
NASA Technical Reports Server (NTRS)
vibrations in the heme (i.e., motion of the iron atom with respect to the plane of the heme) are unaffectedThe Influence of Aqueous versus Glassy Solvents on Protein Dynamics: Vibrational Echo Experiments: Spectrally resolved infrared stimulated vibrational echo measurements are used to measure the vibrational
E-print Network
The purpose of this project is to define specific environmental constraints that influence glassy-winged sharpshooter (GWSS) population dynamics and overwintering success. The production of xylem excreta was used as a measure of GWSS feeding rates. GWSS individuals held at 8.3 to 31.1°C exhibited ...
Technology Transfer Automated Retrieval System (TEKTRAN)
In this paper we attempt to understand the origins of strain hardening response in glassy polymers at large strains through well-designed molecular dynamics (MD) simulations on an atomistic model of a glassy polymer. In the existing constitutive theories of glassy polymers, strain hardening is assumed to be the ...
This report discusses the results of a molecular dynamics (MD) study of molten and glassy SiSe2 using an effective interparticle interaction. Results for the partial pair-correlation functions, partial structure factors and bond-angle distributions are re...
We study the low-temperature dynamics of an elastic manifold driven through a random medium. For driving forces well below the zero- temperature depinning force, the manifold advances via thermally activated hops over the energy barriers separating favora...
, and in a solid trehalose matrix. Measurements are also presented that provide an accurate determination are modified somewhat but are still independent of viscosity. The experiments in trehalose give the dynamics, experiments are also presented on HbCO in trehalose, a glassy solvent at room temperature. Examination
The spontaneous thermodynamically driven densification, the so-called physical aging, of glassy poly(mehtyl methacrylate) (PMMA) and its nanocomposites with silica has been described by means of the free volume holes diffusion model. This mechanism is able to account for the partial decoupling between physical aging and segmental dynamics of PMMA in ...
There is mounting evidence that the surface of glassy polymers exhibits enhanced dynamics compared to the bulk material at the same temperature. Using nanoparticle embedding and relaxation of nanodeformations on the surface, we have developed a detailed characterization of the dynamics of glassy polymers ...
Dynamic compaction of glassy metal powder generally results in denser noncrystalline components than any other consolidation techniques. For example, a density of more than 90 % of the powder material can be achieved by dynamic compaction whereas it is typically about 70-80% for a component obtained by low temperature (below ...
Numerical shear experiments of a granular region using the lattice solid model often exhibit accelerating energy release in the lead-up to large events (Mora et al, 2000) and a growth in correlation lengths in the stress field (Mora and Place, 2002). While these results provide evidence for a Critical Point-like mechanism in elasto-dynamic systems and ...
A methodical investigation and measurement of human dynamic response to impact acceleration was conducted. Linear accelerations were measured on the top of the head, at the mouth, and at the base of the neck. Angular velocity was also measured at the base...
The results of calculating the effect of spread of some static and dynamic characteristics of 50 NP permalloy, of which the main accelerating elements of the linear induction accelerator are made, are described briefly. When making accelerating sections o...
... Resting heart acceleration could be added to typical dead heart response data to predict output acceleration wave forms. ...
... DIRECTION), PHASE, RESONANCE, TRANSLATIONS, CHARGE DENSITY, TRAVELING WAVES, PARTICLE BEAMS, LINEAR ACCELERATORS. ...
The characteristics of dayside electron acceleration regions, or inverted V's, and the nature of the
... TO -Gx IMPACT ACCELERATION N I. Experimental Design and Preliminary Experimental Data ... TO -Gx IMPACT ACCELERATION ...
... the results of a test program in which ejection catapults were test fired both in an environment of zero acceleration (catapult horizontal) and in a ...
... and accelerators, such as MD-GRAPE for molecular dynamics or Clearspeed [148] devices for accelerating floating point computations also show ...
... Accession Number : ADA205108. Title : Acceleration Properties of Planar Manipulators from a Dynamic Standpoint. Descriptive ...
Equations for dynamics without space charge are presented. The dynamic equations are reviewed and new equations for particle dynamics are presented. The two phenomena limiting accelerated current in a proton linear accelerator are reviewed. Beam loading, ...
Cavitation in glassy polymers is known to result from highly triaxial states of local stress and the presence of impurities. Understanding of cavitation, particularly void nucleation, is important as cavities are precursors to crazes, which in turn lead to fracture. In this work we study the early stages of void nucleation in glassy amorphous polymers by ...
The changes in the structure and kinetic properties of glassy and amorphous Si{300}, Si{400}, and Si{500} nanoparticles during heating from 300 to 1700 K are studied by molecular dynamics simulation. The nano-particle density increases with temperature and approaches the density of bulk solid silicon. As the temperature increases to 1400 K, a unimodal bond ...
The axiomatic theory of ideally glassy networks, which has proved effective in describing phase diagrams and properties of chalcogenide and oxide glasses and their foreign interfaces, is broadened here to include intermolecular interactions in hydrogen-bonded polyalcohols such as glycerol, monosaccharides (glucose), and the optimal bioprotective hydrogen-bonded disaccharide ...
We present extensive computational studies of glassy and jamming behavior in particulate systems composed of anisotropic particles in two and three dimensions. We focus on two classes of anisotropic particle shapes, convex (ellipsoidal) and concave (dimer) particles, which display contrasting structural and mechanical properties even at the same aspect ratio. For example, ...
We discuss the behavior of a quantum glassy system coupled to a bath of quantum oscillators. We show that the system localizes in the absence of interactions when coupled to a sub-Ohmic bath. When interactions are switched on localization disappears and the system undergoes a phase transition towards a glassy phase. We show that the position of the ...
The present work demonstrates the deformation behavior of Zr-Cu-Ni-Al bulk glassy alloys and Zr-Ni-Cu-Al-Pd glassy foils as well as Ni-Cu-Ti-Zr bulk crystal-glassy composites. Fracture of Zr60Cu16Ni14Al10 and Zr64.13Ni10.12Cu15.75Al10 bulk glassy alloys is featured by nearly equal fraction areas of cleavage-like ...
A detailed static atomistic model of the defense, glassy polycarbonate of 4,4'-isopropylidenediphenol ('bisphenol-A polycarbonate', PC) is used for a quasi-static simulation of localized motions. These motions include the phenylene ring 'flip', conformati...
The dynamic mechanical behavior (approximately 1 Hz) of four linear phosphazene homopolymers, two copolymers and two physical blends with overall composition approximating the copolymers, was examined between -180 and 250 C in an inert atmosphere. Crystal/melt, crystal/crystal, glass and glassy-state transitions were documented and the effect of high ...
A class of models for relaxation in strongly interacting glassy materials is suggested. Degrees of freedom are divided into a sequence of levels such that those in level n+1 are locked except when some of those in level n find the right combination to release them, this representing the hierarchy of constraints in real systems. The Kohlrausch anomalous relaxation law, ...
Inelastic light scattering was observed in situ from glassy ferroelectric LaBGeO5, which crystallizes the stillwellite-type stoichiometric phase, in the glass--supercooled liquid (SCL) and subsequent SCL--crystal phase transition regimes. The dynamics of the planar BO3 unit in the crystal growth period of the crystallization process was clarified through ...
... warfare, joint planning, national and international ... Rapid Electron Beam Accelerators (REBA-TRONS). ... the beam dynamics in a rebatron accelerator. ...
A model based on a single Brownian particle moving in a periodic effective field is used to understand the non-Gaussian dynamics in glassy systems of cage escape and subsequent recaging, often thought to be caused by a heterogeneous glass structure. The results are compared to molecular-dynamics simulations of systems with varying ...
The glassy dynamics of nanometer thin polymer layers supported on a solid substrate was investigated by Braodband Dielectric Spectroscopy (BDS). The thickness was systematically reduced finally resulting in randomly distributed polymer coils. Highest priority was put on an appropriate sample preparation including an annealing procedure for sufficient long ...
We use time-resolved rheology to elucidate the slow dynamics and aging in highly concentrated suspensions of multiarm star polymers. The linear and nonlinear rheological properties exhibit a terminal regime corresponding to a well-defined maximal relaxation time. Terminal relaxation is driven by arm relaxation which speeds up the escape of stars from their cages. The fact that ...
The theory of single particle dynamics in circular accelerators is developed in this presentation. The Hamiltonian formulation of a relativistic particle in an electromagnetic field is used. (AIP)
The design launch load cases included acceleration loads, dynamic pressures, ... acceleration loads, dynamic pressure loads, and cabin pressure loads for ...
Some of the dynamic characteristics of the human body were analyzed and mathematical analogs that can be used to predict the response of the body to acceleration environments were developed. The background of the acceleration tolerance problem, the basic ...
Molecular dynamics (MD) simulations have been performed to study the dynamics near the glass transition regime of molecular ions in ionic liquids. The glass transition temperature in the simulated 1-ethyl-3-methyl imidazolium nitrate (EMIM-NO(3)) system was determined by plotting density against temperatures. The dynamics at several ...
There are deep analogies between the melting dynamics in systems with a first-order phase transition and the dynamics from equilibrium in super-cooled liquids. For a class of Ising spin models undergoing a first-order transition--namely p-spin models on the so-called Nishimori line--it can be shown that the melting dynamics can be ...
Spatial confinement is known to induce a drastic change in the viscosity, relaxation times, and flow profile of liquids near the glass (or jamming) transition point. The essential underlying question is how a wall affects the dynamics of densely packed systems. Here we study this fundamental problem, using experiments on a driven granular hard-sphere liquid and numerical ...
Recent progress in developing statistical mechanical theories of supercooled polymer melts and glasses is reviewed. The focus is on those approaches that are either explicitly formulated for polymers, or are applications of more generic theories to interpret polymeric phenomena. These include two configurational entropy theories, a percolated free volume distribution model, and the activated ...
We have used rheooptical methods to study polymer chain dynamics in the glassy and melt states in narrow molecular weight fractions of polystyrene: mechanical shear stress and optical retardance were simultaneously monitored during oscillatory shear. The modified stress optical rule (MSOR) of Osaki and coworkers was used to separate ...
Interfacial rheology is the study of the relationship between interfacial stress and the resultant deformation of the interface. We have used this technique to study the 2D rheology of two different polymers, Poly methylmetha acrylate, PMMA and Polyvinylacetate, PVAc, as a function of concentration and temperature. The measured polymers differs widely in their bulk Tg : PMMA (117C) and PVAc (30C). ...
The dynamics of a cylinder rolling on a horizontal plane acted on by an external force applied at an arbitrary angle is studied with emphasis on the directions of the acceleration of the centre-of-mass and the angular acceleration of the body. If rolling occurs without slipping, there is a relationship between the directions of these ...
ERIC Educational Resources Information Center
Slow movement of molecules in glassy matrices controls the kinetics of chemical and physical reactions in dry seeds. Variation in physiological activity among seeds suggests that there are differences in mobility among seed glasses. Testing this hypothesis is difficult because few tools are available to measure molecular mobility within dry seeds. Here, motional properties ...
As an emerging class of photonic and electronic materials, glassy liquid crystals are capable of preserving in the solid state molecular order characteristic of liquid crystals. Because of superior chemical purity and favorable rheological properties, glassy liquid crystals can be readily processed into large-area monodomain films. This thesis aimed at ...
Complementary neutron spin-echo and x-ray experiments and molecular-dynamics simulations have been performed on difluorotetrachloroethane (CFCl2-CFCl2) glassy crystal. Static, single-molecule reorientational dynamics and collective dynamics properties are investigated. Our results confirm the strong analogy between ...
Dynamics and interactions in low temperature glasses can be studied with optical line narrowing techniques applied to chromophores embedded in glassy hosts. Prior to the use of optical methods, a wide variety of classical methods, such as heat capacities,...
... determine whether and how periodic fluctuations in plant water potential are correlated with glassy-winged sharpshooter feeding activity and dispersal. In Brazil, survival of the sharpshooter O. facialis w...
NBII National Biological Information Infrastructure
Results on lanthanum-modified lead zirconate-titanates (PLZTs) have revealed a pressure-induced crossover from a normal ferroelectric to a relaxor state and the continuous evolution of the dynamics and energetics of the relaxation process. This crossover ...
We have used the positron as a microscopic probe to clarify the connection between the microscopic properties (e.g., free volume distributions) and macroscopic properties (pressure, volume, and temperature relations) of polymers in the glassy state. Measu...
The complex response of glassy polymers to high strain-rate dynamic loading necessitates accurate modeling of these events for comparison with experiments. The strain-rate, temperature and the strain softening behavior are significant and must be consider...
Methods for measuring various storage moduli and damping factors of glassy polymers in the frequency range .01 to 10,000,000 Hz are critically reviewed. At frequencies between about .01 and 200 Hz, components of the complex tensile modulus E and Poisson's...
to produce asymptomatic infection with subsequent protective immunity. Sjogren & Sutherland (1975) showed: University of California, Cooperative Extension. Sjogren, I. & Sutherland, J. 1975 Studies of tuberculosis
... to vector Xylella fastidiosa, the causal agent of Pierce�s disease. The glassy-winged sharpshooter is native ... 24, 2008; Accepted: July 9, 2008Keywords: egg maturation, Pierce�s disease, Xylella fastidi...
The glassy winged sharpshooter, Homalodisca coagulata, poses a threat to California's grape industry due to its ability to vector Xylella fastidiosa, the causal agent of Pierce's disease. This insect is an exotic pest in California and is currently the subject of an area wide suppression program. ...
dynamics, first in polymer melts and glasses, and then in adhesion setups. The fundamental inquiry entangle polymer chain ensemble is highlighted. The thesis is concluded by a short outlook of the possible of dense polymer chain ensembles in the melt or glassy state, and during a very common application: polymer
The random energy model (REM) has become a key reference model for glassy systems. In particular, it is expected to provide a prime example of a system whose dynamics shows aging, a universal phenomenon characterizing the dynamics of complex systems. The analysis of its activated dynamics is based on so-called trap ...
... Descriptors : *Electron beams, *Particle accelerators, *Betatrons, *Equations, Dynamics, Toroids, Corrections, Magnetic fields, Walls, Diffusion ...
... Title : A Study of the Dynamic Model Technique in the Analysis of Human Tolerance to Acceleration. Descriptive Note : Technical note. ...
... Descriptors : (*SPINAL COLUMN, ANATOMICAL MODELS), (* CEREBROSPINAL FLUID, FLUID DYNAMICS), (*ACCELERATION ...
In this Perspective, I describe recent work on systems in which the traditional distinctions between (i) unentangled vs. well-entangled systems and (ii) melts vs. glasses seem least useful, and argue for the broader use in glassy polymer mechanics of two more dichotomies: systems which possess (iii) unary vs. binary and (iv) cooperative vs. nonccoperative relaxation ...
We study shear yielding and steady state flow of glassy materials with molecular dynamics simulations of two standard models: amorphous polymers and bidisperse Lennard-Jones glasses. For a fixed strain rate, the maximum shear yield stress and the steady state flow stress in simple shear both drop linearly with increasing temperature. The dependence on ...
We present experimental evidence confirming the recently established rich dynamic state diagram of asymmetric binary mixtures of soft colloidal spheres. These mixtures consist of glassy suspensions of large star polymers to which different small stars are added at varying concentrations. Using rheology and dynamic light scattering ...
Through elastic neutron scattering we investigated the fast dynamics of lysozyme in hydrated powder form or embedded in glycerol-water and glucose-water matrices. We calculated the relaxational contribution to the mean square displacements of protein hydrogen atoms. We found that the inverse of this quantity is linearly proportional to the logarithm of the viscosity of the ...
The Thouless, Anderson and Palmer (TAP) approach to thermodynamics of mean field spin glasses is generalized to dynamics. A method to compute the dynamical TAP equations is developed and applied to the p-spin spherical model. In this context we show to what extent the dynamics can be represented as an evolution in the free energy ...
A collection of notes, on various aspects of beam dynamics in linear accelerators, which were produced by the author during five years (1975 to 1980) of consultation for the LASL Accelerator Technology (AT) Division and Medium-Energy Physics (MP) Division is presented.
DOE Information Bridge
A study has been performed concerning the feasibility and general design of a gas gun accelerator for dynamic warhead tests in the Laboratory for Ballistic Research (LBO) of TNO-PML. The warhead accelerator system under consideration comprises the gas gun...
