Assembly of graphene sheets into 3D macroscopic structures.
Yin, Shengyan; Niu, Zhiqiang; Chen, Xiaodong
2012-08-20
Integration of graphene sheets, 2D nanoscale building blocks, into 3D macroscopic assemblies and ultimately into a functional system is essential to explore the advanced properties of individual graphene sheets for macroscopic applications. This Concept paper summarizes different ways, such as flow-directed assembly, layer-by-layer deposition, template-directed method, and leavening strategy to assemble graphene sheets into the layered and porous 3D macroscopic structures. The obtained structures show unique properties, such as flexible network, high specific surface area, and outstanding electrical and mechanical properties. Furthermore, the functional systems based on such graphene 3D macroscopic structures have shown enhanced performance in the applications of energy storage, catalysis, environmental remediation, and sensing.
Entanglement analysis for macroscopic Schrödinger's Cat state
NASA Astrophysics Data System (ADS)
Sheng, Yu-Bo; Zhou, Lan
2015-02-01
Macroscopic entanglement, or say the Schrödinger's Cat state has attracted much attention for a long time. Recently, the first theoretical work of Fröwis and Dür (Phys. Rev. Lett., 106 (2011) 110402) and the first experiment of Lu et al. (Nat. Photon., 8 (2014) 364) both showed that, a new type of Schrödinger's Cat state, the logic-qubit entanglement (concatenated Greenberger-Horne-Zeilinger (C-GHZ) state) is immune and robust to the noise, and is possible to be applied in future large-scale quantum networks. In this paper, we describe a protocol of entanglement analysis for this kind of Schrödinger's Cat state. Both the Bell-state type of logic-qubit entanglement and multipartite C-GHZ state can be completely distinguished. Based on the entanglement analysis, an arbitrary unknown macroscopic Schrödinger's Cat superposed state can be teleportated and we can also perform the macroscopic entanglement swapping. Our protocol shows that it is possible to realize long-distance quantum communication and large-scale quantum network based on logic-qubit entanglement.
King, Simon; Dimech, Margaret; Johnstone, Susan
2016-06-01
We examined whether introduction of a structured macroscopic reporting template for rectal tumour resection specimens improved the completeness and efficiency in collecting key macroscopic data elements. Fifty free text (narrative) macroscopic reports retrieved from 2012 to 2014 were compared with 50 structured macroscopic reports from 2013 to 2015, all of which were generated at John Hunter Hospital, Newcastle, NSW. The six standard macroscopic data elements examined in this study were reported in all 50 anatomical pathology reports using a structured macroscopic reporting dictation template. Free text reports demonstrated significantly impaired data collection when recording intactness of mesorectum (p<0.001), relationship to anterior peritoneal reflection (p=0.028) and distance of tumour to the non-peritonealised circumferential margin (p<0.001). The number of words used was also significantly (p<0.001) reduced using pre-formatted structured reports compared to free text reports. The introduction of a structured reporting dictation template improves data collection and may reduce the subsequent administrative burden when macroscopically evaluating rectal resections. PMID:27114373
Zhu, Zhongcheng; Li, Yang; Xu, Hui; Peng, Xin; Chen, Ya-Nan; Shang, Cong; Zhang, Qin; Liu, Jiaqi; Wang, Huiliang
2016-06-22
Bulk graphene oxide (GO) nanocomposite materials with macroscopically oriented GO liquid crystalline (LC) structures exhibit interesting anisotropic properties, but their facile preparations remain challenging. This work reports for the first time the facile preparation of poly(N-isopropylacrylamide) (PNIPAM)/GO nanocomposite hydrogels with macroscopically oriented LC structures with the assistance of a flow field induced by vacuum degassing and the in situ polymerization accelerated by GO. The hydrogel prepared with a GO concentration of 5.0 mg mL(-1) exhibits macroscopically aligned LC structures, which endow the gels with anisotropic optical, mechanical properties, and dimensional changes during the phase transition. The hydrogels show dramatically enhanced tensile mechanical properties and phase transition rates. The oriented LC structures are not damaged during the phase transition of the PNIPAM/GO hydrogels, and hence their LC behavior undergoes reversible change. Moreover, highly oriented LC structures can also be formed when the gels are elongated, even for the gels which do not have macroscopically oriented LC structures. Very impressively, the oriented LC structures in the hydrogels can be permanently maintained by drying the gel samples elongated to and then kept at a constant tensile strain. The thermosensitive nature of PNIPAM and the angle-dependent nature of the macroscopically aligned GO LC structures allow the practical applications of the PNIPAM/GO hydrogels as optical switches, soft sensors, and actuators and so on.
Macroscopic effects of the spectral structure in turbulent flows
NASA Astrophysics Data System (ADS)
Tran, T.; Chakraborty, P.; Guttenberg, N.; Prescott, A.; Kellay, H.; Goldburg, W.; Goldenfeld, N.; Gioia, G.
2010-11-01
There is a missing link between macroscopic properties of turbulent flows, such as the frictional drag of a wall-bounded flow, and the turbulent spectrum. To seek the missing link we carry out unprecedented experimental measurements of the frictional drag in turbulent soap-film flows over smooth walls. These flows are effectively two-dimensional, and we are able to create soap-film flows with the two types of turbulent spectrum that are theoretically possible in two dimensions: the "enstrophy cascade," for which the spectral exponent α= 3, and the "inverse energy cascade," for which the spectral exponent α= 5/3. We find that the functional relation between the frictional drag f and the Reynolds number Re depends on the spectral exponent: where α= 3, f ˜Re-1/2; where α= 5/3, f ˜Re-1/4. Each of these scalings may be predicted from the attendant value of α by using a recently proposed spectral theory of the frictional drag. In this theory the frictional drag of turbulent flows on smooth walls is predicted to be f ˜Re^(1-α)/(1+α).
Macroscopic structures of lyotropic lamellar phase under spatial confinement
NASA Astrophysics Data System (ADS)
Iwashita, Yasutaka; Tanaka, Hajime
2004-03-01
We study the formation of lamellar structure of lyotropic liquid crystal composed of C_12E_5/H_2O in wedge-shaped cell. The equilibrium lamellar structure in this cell is known to be an edge dislocation array, which is formed if lamellar layers well align homeotropically to cell surface. When we formed the lamellar phase in the cell, however, some lamellar structures far from equilibrium appeared such as random orientation lamella with dense defects and onion phase in particular condition. This means non-equilibrium, which has not been taken into account so far, is important in this problem. In observing their formation processes in detail, we found the origin of these non-equilibrium lamellar structures is a complex coupling between homo- or heterogeneous nucleation of lamella, elasticity of membrane and spatial confinement (or sample thickness). We will show the relation between spatial confinement and the morphology of structure, and discuss their physical origins.
Micro/macroscopic fluid flow in open cell fibrous structures and porous media
NASA Astrophysics Data System (ADS)
Tamayol, Ali
Fibrous porous materials are involved in a wide range of applications including composite fabrication, filtration, compact heat exchangers, fuel cell technology, and tissue engineering to name a few. Fibrous structures, such as metalfoams, have unique characteristics such as low weight, high porosity, high mechanical strength, and high surface to volume ratio. More importantly, in many applications the fibrous microstructures can be tailored to meet a range of requirements. Therefore, fibrous materials have the potential to be used in emerging sustainable energy conversion applications. The first step for analyzing transport phenomena in porous materials is to determine the micro/macroscopic flow-field inside the medium. In applications where the porous media is confined in a channel, the system performance is tightly related to the flow properties of the porous medium and its interaction with the channel walls, i.e., macroscopic velocity distribution. Therefore, the focus of the study has been on: developing new mechanistic model(s) for determining permeability and inertial coefficient of fibrous porous materials; investigating the effects of microstructural and mechanical parameters such as porosity, fiber orientation, mechanical compression, and fiber distribution on the flow properties and pressure drop of fibrous structures; determining the macroscopic flow-field in confined porous media where the porous structure fills the channel cross-section totally or partially. A systematic approach has been followed to study different aspects of the flow through fibrous materials. The complex microstructure of real materials has been modelled using unit cells that have been assumed to be repeated throughout the media. Implementing various exact and approximate analytical techniques such as integral technique, point matching, blending rules, and scale analysis the flow properties of such media have been modelled; the targeted properties include permeability and inertial
Structure and macroscopic tackiness of ultrathin pressure sensitive adhesive films.
Diethert, Alexander; Körstgens, Volker; Magerl, David; Ecker, Katharina; Perlich, Jan; Roth, Stephan V; Müller-Buschbaum, Peter
2012-08-01
Ultrathin layers of the statistical copolymer P(nBA-stat-MA) with a majority of n-butyl acrylate (nBA) and a minority of methyl acrylate (MA) are characterized with respect to the film morphology and the mechanical response in a probe tack test. The probed copolymer can be regarded as a model system of a pressure sensitive adhesive (PSA). The films are prepared by spin-coating which enables an easy thickness control via the polymer concentration of the solution. The film thickness is determined with x-ray reflectivity (XRR) and white light interferometry (WLI). Grazing incidence small angle x-ray scattering (GISAXS) provides detailed and statistically significant information about the film morphology. Two types of lateral structures are identified and no strong correlation of these structures with the PSA film thickness is observed. In contrast, prominent parameters of the probe tack test, such as the stress maximum and the tack energy, exhibit an exponential dependence on the film thickness. PMID:22817560
Structure and macroscopic tackiness of ultrathin pressure sensitive adhesive films.
Diethert, Alexander; Körstgens, Volker; Magerl, David; Ecker, Katharina; Perlich, Jan; Roth, Stephan V; Müller-Buschbaum, Peter
2012-08-01
Ultrathin layers of the statistical copolymer P(nBA-stat-MA) with a majority of n-butyl acrylate (nBA) and a minority of methyl acrylate (MA) are characterized with respect to the film morphology and the mechanical response in a probe tack test. The probed copolymer can be regarded as a model system of a pressure sensitive adhesive (PSA). The films are prepared by spin-coating which enables an easy thickness control via the polymer concentration of the solution. The film thickness is determined with x-ray reflectivity (XRR) and white light interferometry (WLI). Grazing incidence small angle x-ray scattering (GISAXS) provides detailed and statistically significant information about the film morphology. Two types of lateral structures are identified and no strong correlation of these structures with the PSA film thickness is observed. In contrast, prominent parameters of the probe tack test, such as the stress maximum and the tack energy, exhibit an exponential dependence on the film thickness.
NASA Astrophysics Data System (ADS)
Sandhage, Kenneth H.
2010-06-01
The scalable fabrication of nano-structured materials with complex morphologies and tailorable chemistries remains a significant challenge. One strategy for such synthesis consists of the generation of a solid structure with a desired morphology (a “preform”), followed by reactive conversion of the preform into a new chemistry. Several gas/solid and liquid/solid reaction processes that are capable of such chemical conversion into new micro-to-nano-structured materials, while preserving the macroscopic-to-microscopic preform morphologies, are described in this overview. Such shape-preserving chemical transformation of one material into another could be considered a modern type of materials “alchemy.”
NASA Astrophysics Data System (ADS)
Alexander, F.; Villagrasa, C.; Rabus, H.; Wilkens, J. J.
2015-12-01
The research project BioQuaRT within the European Metrology Research Programme aimed at correlating ion track structure characteristics with the biological effects of radiation and developed measurement and simulation techniques for determining ion track structure on different length scales from about 2 nm to about 10 μm. Within this framework, we investigated methods to translate track-structure quantities derived on a nanometre scale to macroscopic dimensions. Here we make use of parameterizations that link the energy of the projectile to the ionization pattern of the track using nanodosimetric ionization cluster size distributions. They were defined with data generated by simulations of ion tracks in liquid water using the Geant4 Monte Carlo toolkit with the Geant4-DNA processes. For the clinical situation with a mixed radiation field, where particles of various energies hit a cell from several directions, we have to find macroscopic relevant mean values. They can be determined by appropriate local weighting functions for the identified parameterization. We show that a stopping power weighted mean value of the mentioned track structure properties can describe the overall track structure in a cell exposed to a mixed radiation field. The parameterization, together with the presented stopping power weighting approach, show how nanometric track structure properties could be integrated into treatment planning systems without the need to perform time consuming simulations on the nanometer level for each individual patient.
Macroscopic analysis of axisymmetric functionally gradient material under thermal loading
Kwon, P.; Dharan, C.K.H.; Ferrari, M. )
1994-06-01
The axisymmetric functionally gradient materials (FGMs) subject to nonuniform temperature variations were studied with the combined use of homogenization and inhomogeneous eigenstrained media analysis. The material properties and the temperature variations were assumed to depend on the radial coordinate only. The inhomogeneous material properties of the FGM cylinder can be obtained by modulating the concentration level of spherical alumina particles in an aluminum matrix. The resulting stresses due to the temperature variation are presented for numerous distribution functions of alumina particles. It is shown that the particle distribution extensively influences the intensity and profile of the thermal stresses.
López-López, María; Merk, Virginia; García-Ruiz, Carmen; Kneipp, Janina
2016-07-01
Gunshot residues (GSR) result from the discharge of a firearm being a potential piece of evidence in criminal investigations. The macroscopic GSR particles are basically formed by burned and non-burned gunpowder. Motivated by the demand of trace analysis of these samples, in this paper, the use of surface-enhanced Raman scattering (SERS) was evaluated for the analysis of gunpowders and macroscopic GSR particles. Twenty-one different smokeless gunpowders were extracted with ethanol. SERS spectra were obtained from the diluted extracts using gold nanoaggregates and an excitation wavelength of 633 nm. They show mainly bands that could be assigned to the stabilizers diphenylamine and ethylcentralite present in the gunpowders. Then, macroscopic GSR particles obtained after firing two different ammunition cartridges on clothing were also measured using the same procedure. SERS allowed the detection of the particles collected with an aluminum stub from cloth targets without interferences from the adhesive carbon. The results demonstrate the great potential of SERS for the analysis of macroscopic GSR particles. Furthermore, they indicate that the grain-to-grain inhomogeneity of the gunpowders needs to be considered. Graphical Abstract SERS allows the detection of GSR particles collected with adhesive stubs from cloth targets using gold nanoaggregates and an excitation wavelength of 633 nm. PMID:27137517
López-López, María; Merk, Virginia; García-Ruiz, Carmen; Kneipp, Janina
2016-07-01
Gunshot residues (GSR) result from the discharge of a firearm being a potential piece of evidence in criminal investigations. The macroscopic GSR particles are basically formed by burned and non-burned gunpowder. Motivated by the demand of trace analysis of these samples, in this paper, the use of surface-enhanced Raman scattering (SERS) was evaluated for the analysis of gunpowders and macroscopic GSR particles. Twenty-one different smokeless gunpowders were extracted with ethanol. SERS spectra were obtained from the diluted extracts using gold nanoaggregates and an excitation wavelength of 633 nm. They show mainly bands that could be assigned to the stabilizers diphenylamine and ethylcentralite present in the gunpowders. Then, macroscopic GSR particles obtained after firing two different ammunition cartridges on clothing were also measured using the same procedure. SERS allowed the detection of the particles collected with an aluminum stub from cloth targets without interferences from the adhesive carbon. The results demonstrate the great potential of SERS for the analysis of macroscopic GSR particles. Furthermore, they indicate that the grain-to-grain inhomogeneity of the gunpowders needs to be considered. Graphical Abstract SERS allows the detection of GSR particles collected with adhesive stubs from cloth targets using gold nanoaggregates and an excitation wavelength of 633 nm.
Majumdar, A.; Alencar, A. M.; Buldyrev, S. V.; Hantos, Z.; Stanley, H. E.; Suki, B.
2001-07-30
We analyze the problem of fluid flow in a bifurcating structure containing random blockages that can be removed by fluid pressure. We introduce an asymmetric tree model and find that the predicted pressure-volume relation is connected to the distribution {Pi}(n) of the generation number n of the tree's terminal segments. We use this relation to explore the branching structure of the lung by analyzing experimental pressure-volume data from dog lungs. The {Pi}(n) extracted from the data using the model agrees well with experimental data on the branching structure. We can thus obtain information about the asymmetric structure of the lung from macroscopic, noninvasive pressure-volume measurements.
NASA Astrophysics Data System (ADS)
Rowe, D. J.; McCoy, A. E.; Caprio, M. A.
2016-03-01
The nuclear collective models introduced by Bohr, Mottelson and Rainwater, together with the Mayer-Jensen shell model, have provided the central framework for the development of nuclear physics. This paper reviews the microscopic evolution of the collective models and their underlying foundations. In particular, it is shown that the Bohr-Mottelson models have expressions as macroscopic limits of microscopic models that have precisely defined expressions in many-nucleon quantum mechanics. Understanding collective models in this way is especially useful because it enables the analysis of nuclear properties in terms of them to be revisited and reassessed in the light of their microscopic foundations.
Shiba, Kiyotaka; Honma, Takako; Minamisawa, Tamiko; Nishiguchi, Keiichi; Noda, Tetsuo
2003-02-01
By controlling the growth of inorganic crystals, macro-biomolecules, including proteins, play pivotal roles in modulating biomineralization. Natural proteins that promote biomineralization are often composed of simple repeats of peptide sequences; however, the relationship between these repetitive structures and their functions remains largely unknown. Here we show that an artificial protein containing a repeated peptide sequence allows NaCl, KCl, CuSO(4) and sucrose to form a variety of macroscopic structures, as represented by their dendritic configurations. Mutational analyses revealed that the physicochemical characteristics of the protein, not the peptide sequence per se, were responsible for formation of the dendritic structures. This suggests that proteins that modulate crystal growth may have evolved as repeat-containing forms at a relatively high rate. These observations could serve as the basis for developing new genetic programming systems for creation of artificial proteins able to modulate crystal growth from inorganic compounds, and may thus provide a new tool for nano-biotechnology.
Controlled preparation and structure characterization of BiFeO{sub 3} with macroscopic shapes
Wu, Qiang; Chen, Pengfei; Zhao, Li; Yao, Weifeng; Qi, Xuemei
2015-01-15
Graphical abstract: We firstly explored two facile and successful techniques for BiFeO{sub 3} immobilization on silica fiber, namely, a combined impregnation method with carbon nanofibers (CNFs) templates route, and a combined solvothermal method with CNFs templates route. It is expected that such materials with direct macroscopic shapes would hold promise as highly functionalized materials for potential practical applications, especially in photocatalysis. - Highlights: • BiFeO{sub 3} with macroscopic shape was successfully obtained. • The synthetic methods used here are facile, effective, and reproducible. • Phase composition was strongly affected by calcination temperatures. • The obtained materials are promising visible-light-driven photocatalysts. - Abstract: BiFeO{sub 3} was successfully immobilized on silica fiber via two synthetic techniques (a combined impregnation method with carbon nanofibers templates route; a combined solvothermal method with carbon nanofibers templates route). The phase structure, morphology and optical absorption property of the samples were characterized by X-ray diffraction, field emission scanning electron microscopy, and ultraviolet–visible diffuse reflectance spectroscopy. The results confirmed that carbon nanofibers can act as effective templates for BiFeO{sub 3} immobilization on silica fiber with the applied two methods. Compared with solvent thermal method, impregnation method tends to form a relatively uniform particle size distribution and highly-crystallized phase when the calcination temperature was kept at 773 K for 5 h. It turned out the phase composition of the samples is strongly affected by the calcination temperatures for both cases. Such materials with direct macroscopic shapes would hold promise as highly functionalized materials for potential practical applications, especially in photocatalysis.
Macroscopic and microscopic analysis of knife stab wounds on fleshed and clothed ribs.
Ferllini, Roxana
2012-05-01
Stab wounds upon bone are analyzed to interpret the weapon used and the physical context in which the attack occurred. The literature demonstrates that most research conducted pertaining to wound patterns has been carried out on defleshed and unclothed bone samples, not adequately replicating actual circumstances. For this research, six half pig torsos (Sus scrofa), fleshed (including muscle, fat, epidermis, and dermis layers) and clothed, were stabbed using three knife types, applying both straight and downward thrusts. Analysis conducted macroscopically and through a scanning electron microscope with an environmental secondary electron detector revealed a general lack of consistency in wound pattern and associated secondary effects. Consequently, it was not possible to establish wound pattern per knife type as suggested in previous research or relate it to stab motion. Advantage of microscopic analysis was evident in recognizing wound traits and observation of trace evidence not visible macroscopically.
Kotani, Kiyoshi; Yamaguchi, Ikuhiro; Yoshida, Lui; Jimbo, Yasuhiko; Ermentrout, G. Bard
2014-01-01
Gamma oscillations of the local field potential are organized by collective dynamics of numerous neurons and have many functional roles in cognition and/or attention. To mathematically and physiologically analyse relationships between individual inhibitory neurons and macroscopic oscillations, we derive a modification of the theta model, which possesses voltage-dependent dynamics with appropriate synaptic interactions. Bifurcation analysis of the corresponding Fokker–Planck equation (FPE) enables us to consider how synaptic interactions organize collective oscillations. We also develop the adjoint method (infinitesimal phase resetting curve) for simultaneous equations consisting of ordinary differential equations representing synaptic dynamics and a partial differential equation for determining the probability distribution of the membrane potential. This method provides a macroscopic phase response function (PRF), which gives insights into how it is modulated by external perturbation or internal changes of parameters. We investigate the effects of synaptic time constants and shunting inhibition on these gamma oscillations. The sensitivity of rising and decaying time constants is analysed in the oscillatory parameter regions; we find that these sensitivities are not largely dependent on rate of synaptic coupling but, rather, on current and noise intensity. Analyses of shunting inhibition reveal that it can affect both promotion and elimination of gamma oscillations. When the macroscopic oscillation is far from the bifurcation, shunting promotes the gamma oscillations and the PRF becomes flatter as the reversal potential of the synapse increases, indicating the insensitivity of gamma oscillations to perturbations. By contrast, when the macroscopic oscillation is near the bifurcation, shunting eliminates gamma oscillations and a stable firing state appears. More interestingly, under appropriate balance of parameters, two branches of bifurcation are found in our
Shock structure and temperature overshoot in macroscopic multi-temperature model of mixtures
Madjarević, Damir Simić, Srboljub; Ruggeri, Tommaso
2014-10-15
The paper discusses the shock structure in macroscopic multi-temperature model of gaseous mixtures, recently established within the framework of extended thermodynamics. The study is restricted to weak and moderate shocks in a binary mixture of ideal gases with negligible viscosity and heat conductivity. The model predicts the existence of temperature overshoot of heavier constituent, like more sophisticated approaches, but also puts in evidence its non-monotonic behavior not documented in other studies. This phenomenon is explained as a consequence of weak energy exchange between the constituents, either due to large mass difference, or large rarefaction of the mixture. In the range of small Mach number it is also shown that shock thickness (or equivalently, the inverse of Knudsen number) decreases with the increase of Mach number, as well as when the mixture tends to behave like a single-component gas (small mass difference and/or presence of one constituent in traces)
Using the dynamic bond to access macroscopically responsive structurally dynamic polymers
NASA Astrophysics Data System (ADS)
Wojtecki, Rudy J.; Meador, Michael A.; Rowan, Stuart J.
2011-01-01
New materials that have the ability to reversibly adapt to their environment and possess a wide range of responses ranging from self-healing to mechanical work are continually emerging. These adaptive systems have the potential to revolutionize technologies such as sensors and actuators, as well as numerous biomedical applications. We will describe the emergence of a new trend in the design of adaptive materials that involves the use of reversible chemistry (both non-covalent and covalent) to programme a response that originates at the most fundamental (molecular) level. Materials that make use of this approach - structurally dynamic polymers - produce macroscopic responses from a change in the material's molecular architecture (that is, the rearrangement or reorganization of the polymer components, or polymeric aggregates). This design approach requires careful selection of the reversible/dynamic bond used in the construction of the material to control its environmental responsiveness.
State-space based analysis and forecasting of macroscopic road safety trends in Greece.
Antoniou, Constantinos; Yannis, George
2013-11-01
In this paper, macroscopic road safety trends in Greece are analyzed using state-space models and data for 52 years (1960-2011). Seemingly unrelated time series equations (SUTSE) models are developed first, followed by richer latent risk time-series (LRT) models. As reliable estimates of vehicle-kilometers are not available for Greece, the number of vehicles in circulation is used as a proxy to the exposure. Alternative considered models are presented and discussed, including diagnostics for the assessment of their model quality and recommendations for further enrichment of this model. Important interventions were incorporated in the models developed (1986 financial crisis, 1991 old-car exchange scheme, 1996 new road fatality definition) and found statistically significant. Furthermore, the forecasting results using data up to 2008 were compared with final actual data (2009-2011) indicating that the models perform properly, even in unusual situations, like the current strong financial crisis in Greece. Forecasting results up to 2020 are also presented and compared with the forecasts of a model that explicitly considers the currently on-going recession. Modeling the recession, and assuming that it will end by 2013, results in more reasonable estimates of risk and vehicle-kilometers for the 2020 horizon. This research demonstrates the benefits of using advanced state-space modeling techniques for modeling macroscopic road safety trends, such as allowing the explicit modeling of interventions. The challenges associated with the application of such state-of-the-art models for macroscopic phenomena, such as traffic fatalities in a region or country, are also highlighted. Furthermore, it is demonstrated that it is possible to apply such complex models using the relatively short time-series that are available in macroscopic road safety analysis.
Nono, Yoshihiro; Mouri, Emiko; Nakata, Munetaka; Nakato, Teruyuki
2016-03-01
Multiscale structures of anisotropic nanoparticles up to macroscopic scales are important in order to produce practical materials through nanotechnology. As an example of such structures, hierarchical organization of colloidal liquid crystals of niobium oxide nanosheets yields stripe textures observable by naked eyes. The stripes are generated by the growth of liquid crystalline domains (tactoids) and the alignment of the tactoids under an electric field and gravity applied in the directions orthogonal to each other. The nanosheets forming the tactoids are unidirectionally aligned along the flow induced by gravity, and the aligned tactoids are stretched to be connected each other to form the stripes. Time evolution of the stripes indicates that they are generated during the settlement of the nanosheets. The nanosheets are debundled with the settlement, and thus the stripes are gradually degenerated during the settlement. Larger tactoids cause faster nanosheet settlement and stripe degeneration. The electric field applied orthogonally to gravity has roles of pinning the nanosheets to slow down their settlement and retains the stripes for several hours. PMID:27455743
NASA Astrophysics Data System (ADS)
Kanick, Stephen C.
2016-03-01
The onset and progression of cancer introduces changes to the intra-cellular ultrastructural components and to the morphology of the extracellular matrix. While previous work has shown that localized scatter imaging is sensitive to pathology-induced differences in these aspects of tissue microstructure, wide adaptation this knowledge for surgical guidance is limited by two factors. First, the time required to image with confocal-level localization of the remission signal can be substantial. Second, localized (i.e. sub-diffuse) scatter remission intensity is influenced interchangeably by parameters that define scattering frequency and anisotropy. This similarity relationship must be carefully considered in order to obtain unique estimates of biomarkers that define either the scatter density or features that describe the distribution (e.g. shape, size, and orientation) of scatterers. This study presents a novel approach that uses structured light imaging to address both of these limitations. Monte Carlo data were used to model the reflectance intensity over a wide range of spatial frequencies, reduced scattering coefficients, absorption coefficients, and a metric of the scattering phase function that directly maps to the fractal dimension of scatter sizes. The approach is validated in tissue-simulating phantoms constructed with user-tuned scattering phase functions. The validation analysis shows that the phase function can be described in the presence of different scatter densities or background absorptions. Preliminary data from clinical tissue specimens show quantitative images of both the scatter density and the tissue fractal dimension for various tissue types and pathologies. These data represent a novel wide-field quantitative approach to mapping microscopic structural biomarkers that cannot be obtained with standard diffuse imaging. Implications for the use of this approach to assess surgical margins will be discussed.
Macroscopic and microscopic analysis of mass transfer in reversed phase liquid chromatography.
Bacskay, Ivett; Felinger, Attila
2009-02-20
For the correct description of a chromatographic process, the determination of mass-transfer kinetics in the column is required because the influence of the mass-transfer kinetics on the shape of chromatographic band profiles is crucial. Several sources of mass transfer in a chromatographic bed have been identified and studied: the axial dispersion in the stream of mobile phase, the external mass-transfer resistance, intraparticle diffusion, and the kinetics of adsorption-desorption In this study we compare mass-transfer coefficients obtained in a reversed phase chromatographic column using macroscopic and microscopic approaches. The general rate model, the plate height equation, moment analysis, and stochastic analysis were used to assess chromatographic process during the separation of alkylbenzenes.
Macroscopic and histopathologic analysis of human knee menisci in aging and osteoarthritis
Pauli, C.; Grogan, S.P.; Patil, S.; Otsuki, S.; Hasegawa, A.; Koziol, J.; Lotz, M.K.; D’Lima, D.D.
2011-01-01
Objective Meniscus lesions following trauma or associated with osteoarthritis (OA) have been described, yet meniscus aging has not been systematically analyzed. The objectives of this study were to (i) establish standardized protocols for representative macroscopic and microscopic analysis, (ii) improve existing scoring systems, and (iii) apply these techniques to a large number of human menisci. Design Medial and lateral menisci from 107 human knees were obtained and cut in two different planes (triangle/crossection and transverse/horizontal) in three separate locations (mid portion, anterior and posterior horns). All sections included vascular and avascular regions and were graded for i) surface integrity, ii) cellularity, iii) matrix/fiber organization and collagen alignment, and iv) Safranin-O staining intensity. The cartilage in all knee compartments was also scored. Results The new macroscopic and microscopic grading systems showed high inter-reader and intra-reader intraclass correlation coefficients. The major age-related changes in menisci in joints with no or minimal OA included increased Safranin-O staining intensity, decreased cell density, the appearance of acellular zones, and evidence of mucoid degeneration with some loss of collagen fiber organization. The earliest meniscus changes occurred predominantly along the inner rim. Menisci from OA joints showed severe fibrocartilaginous separation of the matrix, extensive fraying, tears and calcification. Abnormal cell arrangements included decreased cellularity, diffuse hypercellularity along with cellular hypertrophy and abnormal cell clusters. In general, the anterior horns of both medial and lateral menisci were less affected by age and OA. Conclusions New standardized protocols and new validated grading systems allowed us to conduct a more systematic evaluation of changes in aging and OA menisci at a macroscopic and microscopic level. Several meniscus abnormalities appear to be specific to aging in
Carreón-Calderón, Bernardo
2012-10-14
Stability analysis is generally used to verify that the solution to phase equilibrium calculations corresponds to a stable state (minimum of the free energy). In this work, tangent plane distance analysis for stability of macroscopic mixtures is also used for analyzing the nucleation process, reconciling thus this analysis with classical nucleation theories. In the context of the revised nucleation theory, the driving force and the nucleation work are expressed as a function of the Lagrange multiplier corresponding to the mole fraction constraint from the minimization problem of stability analysis. Using a van der Waals fluid applied to a ternary mixture, Lagrange multiplier properties are illustrated. In particular, it is shown how the Lagrange multiplier value is equal to one on the binodal and spinodal curves at the same time as the driving force of nucleation vanishes on these curves. Finally, it is shown that, on the spinodal curve, the nucleation work from the revised and generalized nucleation theories are characterized by two different local minima from stability analysis, irrespective of any interfacial tension models. PMID:23061836
Carreón-Calderón, Bernardo
2012-10-14
Stability analysis is generally used to verify that the solution to phase equilibrium calculations corresponds to a stable state (minimum of the free energy). In this work, tangent plane distance analysis for stability of macroscopic mixtures is also used for analyzing the nucleation process, reconciling thus this analysis with classical nucleation theories. In the context of the revised nucleation theory, the driving force and the nucleation work are expressed as a function of the Lagrange multiplier corresponding to the mole fraction constraint from the minimization problem of stability analysis. Using a van der Waals fluid applied to a ternary mixture, Lagrange multiplier properties are illustrated. In particular, it is shown how the Lagrange multiplier value is equal to one on the binodal and spinodal curves at the same time as the driving force of nucleation vanishes on these curves. Finally, it is shown that, on the spinodal curve, the nucleation work from the revised and generalized nucleation theories are characterized by two different local minima from stability analysis, irrespective of any interfacial tension models.
Braunschweig, Björn; Schulze-Zachau, Felix; Nagel, Eva; Engelhardt, Kathrin; Stoyanov, Stefan; Gochev, Georgi; Khristov, Khr; Mileva, Elena; Exerowa, Dotchi; Miller, Reinhard; Peukert, Wolfgang
2016-07-01
β-Lactoglobulin (BLG) adsorption layers at air-water interfaces were studied in situ with vibrational sum-frequency generation (SFG), tensiometry, surface dilatational rheology and ellipsometry as a function of bulk Ca(2+) concentration. The relation between the interfacial molecular structure of adsorbed BLG and the interactions with the supporting electrolyte is additionally addressed on higher length scales along the foam hierarchy - from the ubiquitous air-water interface through thin foam films to macroscopic foam. For concentrations <1 mM, a strong decrease in SFG intensity from O-H stretching bands and a slight increase in layer thickness and surface pressure are observed. A further increase in Ca(2+) concentrations above 1 mM causes an apparent change in the polarity of aromatic C-H stretching vibrations from interfacial BLG which we associate to a charge reversal at the interface. Foam film measurements show formation of common black films at Ca(2+) concentrations above 1 mM due to considerable decrease of the stabilizing electrostatic disjoining pressure. These observations also correlate with a minimum in macroscopic foam stability. For concentrations >30 mM Ca(2+), micrographs of foam films show clear signatures of aggregates which tend to increase the stability of foam films. Here, the interfacial layers have a higher surface dilatational elasticity. In fact, macroscopic foams formed from BLG dilutions with high Ca(2+) concentrations where aggregates and interfacial layers with higher elasticity are found, showed the highest stability with much smaller bubble sizes.
A Macroscopic Mathematical Model for Cell Migration Assays Using a Real-Time Cell Analysis
Angelini, Claudia; Carfora, Maria Francesca; Carriero, Maria Vincenza; Natalini, Roberto
2016-01-01
Experiments of cell migration and chemotaxis assays have been classically performed in the so-called Boyden Chambers. A recent technology, xCELLigence Real Time Cell Analysis, is now allowing to monitor the cell migration in real time. This technology measures impedance changes caused by the gradual increase of electrode surface occupation by cells during the course of time and provide a Cell Index which is proportional to cellular morphology, spreading, ruffling and adhesion quality as well as cell number. In this paper we propose a macroscopic mathematical model, based on advection-reaction-diffusion partial differential equations, describing the cell migration assay using the real-time technology. We carried out numerical simulations to compare simulated model dynamics with data of observed biological experiments on three different cell lines and in two experimental settings: absence of chemotactic signals (basal migration) and presence of a chemoattractant. Overall we conclude that our minimal mathematical model is able to describe the phenomenon in the real time scale and numerical results show a good agreement with the experimental evidences. PMID:27680883
NASA Astrophysics Data System (ADS)
Fuchs, Alexander N.; Wirth, Franz X.; Rinck, Philipp; Zaeh, Michael F.
Structural lightweight construction is increasingly utilized in the aerospace and automotive industry. Hybrid structures have great potential, especially with regard to load-specific component layouts. Usually, a surface pre-treatment is applied prior to joining dissimilar materials to improve bonding mechanisms such as form closure. In previous studies pulsed wave (pw) lasers were used for structuring metals. This paper presents the results of aluminum pre-treatment via a continuous wave (cw) single-mode fiber laser: macroscopic and microscopic structures were generated on the aluminum surface; the samples were joined with glass fiber reinforced polyamide using Friction Press Joining (FPJ), a method for joining metals and thermoplastic polymers in lap joint configuration. Using these new methods for surface structuring, shear strength was increased by 40% compared to previous studies with pw lasers.
Moran, J.M.; Nigg, D.W.; Wheeler, F.J.; Bauer, W.F. )
1992-05-01
Calculations of radiation flux and dose distributions for boron neutron capture therapy (BNCT) of brain tumors are typically performed using sophisticated three-dimensional analytical models based on either a homogeneous approximation or a simplified few-region approximation to the actual highly heterogeneous geometry of the irradiation volume. Such models should be validated by comparison with calculations using detailed models in which all significant macroscopic tissue heterogeneities and geometric structures are explicitly represented as faithfully as possible. This paper describes such a validation exercise for BNCT of canine brain tumors. Geometric measurements of the canine anatomical structures of interest for this work were performed by dissecting and examining two essentially identical Labrador retriever heads. Chemical analyses of various tissue samples taken during the dissections were conducted to obtain measurements of elemental compositions for the tissues of interest. The resulting geometry and tissue composition data were then used to construct a detailed heterogeneous calculational model of the Labrador head. Calculations of three-dimensional radiation flux distributions pertinent to BNCT were performed for this model using the TORT discrete-ordinates radiation transport code. The calculations were repeated for a corresponding volume-weighted homogeneous-tissue model. Comparison of the results showed that peak neutron and photon flux magnitudes were quite similar for the two models (within 5%), but that the spatial flux profiles were shifted in the heterogeneous model such that the fluxes in some locations away from the peak differed from the corresponding fluxes in the homogeneous model by as much as 10%--20%. Differences of this magnitude can be therapeutically significant, emphasizing the need for proper validation of simplified treatment planning models.
NASA Astrophysics Data System (ADS)
Crankshaw, D. S.; Segall, K.; Nakada, D.; Orlando, T. P.; Levitov, L. S.; Lloyd, S.; Valenzuela, S. O.; Markovic, N.; Tinkham, M.; Berggren, K. K.
2004-04-01
dc measurements are made in a superconducting, persistent current qubit structure with a time-ordered meter. The persistent-current qubit has a double-well potential, with the two minima corresponding to magnetization states of opposite sign. Macroscopic resonant tunneling between the two wells is observed at values of energy bias that correspond to the positions of the calculated quantum levels. The magnetometer, a superconducting quantum interference device, detects the state of the qubit in a time-ordered fashion, measuring one state before the other. This results in a different meter output depending on the initial state, providing different signatures of the energy levels for each tunneling direction.
Shi, Xiaomeng; Ye, Zhirui; Shiwakoti, Nirajan; Tang, Dounan; Wang, Chao; Wang, Wei
2016-10-01
A recent crowd stampede during a New Year's Eve celebration in Shanghai, China resulted in 36 fatalities and over 49 serious injuries. Many of such tragic crowd accidents around the world resulted from complex multi-direction crowd movement such as merging behavior. Although there are a few studies on merging crowd behavior, none of them have conducted a systematic analysis considering the impact of both merging angle and flow direction towards the safety of pedestrian crowd movement. In this study, a series of controlled laboratory experiments were conducted to examine the safety constraints of merging pedestrian crowd movements considering merging angle (60°, 90° and 180°) and flow direction under slow running and blocked vision condition. Then, macroscopic and microscopic properties of crowd dynamics are obtained and visualized through the analysis of pedestrian crowd trajectory data derived from video footage. It was found that merging angle had a significant influence on the fluctuations of pedestrian flows, which is important in a critical situation such as emergency evacuation. As the merging angle increased, mean velocity and mean flow at the measuring region in the exit corridors decreased, while mean density increased. A similar trend was observed for the number of weaving and overtaking conflicts, which resulted in the increase of mean headway. Further, flow direction had a significant impact on the outflow of the individuals while blocked vision had an influence on pedestrian crowd interactions and merging process. Finally, this paper discusses safety assessments on crowd merging behaviors along with some recommendations for future research. Findings from this study can assist in the development and validation of pedestrian crowd simulation models as well as organization and control of crowd events.
Wilson, Samantha L; Guilbert, Marie; Sulé-Suso, Josep; Torbet, Jim; Jeannesson, Pierre; Sockalingum, Ganesh D; Yang, Ying
2014-01-01
During aging, collagen structure changes, detrimentally affecting tissues' biophysical and biomechanical properties due to an accumulation of advanced glycation end-products (AGEs). In this investigation, we conducted a parallel study of microscopic and macroscopic properties of different-aged collagens from newborn to 2-yr-old rats, to examine the effect of aging on fibrillogenesis, mechanical and contractile properties of reconstituted hydrogels from these collagens seeded with or without fibroblasts. In addition to fibrillogenesis of collagen under the conventional conditions, some fibrillogenesis was conducted alongside a 12-T magnetic field, and gelation rate and AGE content were measured. A nondestructive indentation technique and optical coherence tomography were used to determine the elastic modulus and dimensional changes, respectively. It was revealed that in comparison to younger specimens, older collagens exhibited higher viscosity, faster gelation rates, and a higher AGE-specific fluorescence. Exceptionally, only young collagens formed highly aligned fibrils under magnetic fields. The youngest collagen demonstrated a higher elastic modulus and contraction in comparison to the older collagen. We conclude that aging changes collagen monomer structure, which considerably affects the fibrillogenesis process, the architecture of the resulting collagen fibers and the global network, and the macroscopic properties of the formed constructs.
No effect of schizophrenia risk genes MIR137, TCF4, and ZNF804A on macroscopic brain structure.
Cousijn, Helena; Eissing, Marc; Fernández, Guillén; Fisher, Simon E; Franke, Barbara; Zwiers, Marcel; Harrison, Paul J; Arias-Vásquez, Alejandro
2014-11-01
Single nucleotide polymorphisms (SNPs) within the MIR137, TCF4, and ZNF804A genes show genome-wide association to schizophrenia. However, the biological basis for the associations is unknown. Here, we tested the effects of these genes on brain structure in 1300 healthy adults. Using volumetry and voxel-based morphometry, neither gene-wide effects--including the combined effect of the genes--nor single SNP effects--including specific psychosis risk SNPs--were found on total brain volume, grey matter, white matter, or hippocampal volume. These results suggest that the associations between these risk genes and schizophrenia are unlikely to be mediated via effects on macroscopic brain structure.
NASA Astrophysics Data System (ADS)
Iyer, Mrinal; Radhakrishnan, Balachandran; Gavini, Vikram
2015-03-01
We employed a real-space formulation of orbital-free density functional theory using finite-element basis to study the defect-core and energetics of an edge dislocation in Aluminum. Our study shows that the core-size of a perfect edge dislocation is around ten times the magnitude of the Burgers vector. This finding is contrary to the widely accepted notion that continuum descriptions of dislocation energetics are accurate beyond ∼1-3 Burgers vector from the dislocation line. Consistent with prior electronic-structure studies, we find that the perfect edge dislocation dissociates into two Shockley partials with a partial separation distance of 12.8 Å. Interestingly, our study revealed a significant influence of macroscopic deformations on the core-energy of Shockley partials. We show that this dependence of the core-energy on macroscopic deformations results in an additional force on dislocations, beyond the Peach-Koehler force, that is proportional to strain gradients. Further, we demonstrate that this force from core-effects can be significant and can play an important role in governing the dislocation behavior in regions of inhomogeneous deformations.
Lucia, Umberto
2016-01-01
The relation between macroscopic irreversibility and microscopic reversibility is a present unsolved problem. Constructal law is introduced to develop analytically the Einstein’s, Schrödinger’s, and Gibbs’ considerations on the interaction between particles and thermal radiation (photons). The result leads to consider the atoms and molecules as open systems in continuous interaction with flows of photons from their surroundings. The consequent result is that, in any atomic transition, the energy related to the microscopic irreversibility is negligible, while when a great number of atoms (of the order of Avogadro’s number) is considered, this energy related to irreversibility becomes so large that its order of magnitude must be taken into account. Consequently, macroscopic irreversibility results related to microscopic irreversibility by flows of photons and amount of atoms involved in the processes. PMID:27762333
NASA Technical Reports Server (NTRS)
1991-01-01
After an 800-foot-tall offshore oil recovery platform collapsed, the engineers at Engineering Dynamics, Inc., Kenner, LA, needed to learn the cause of the collapse, and analyze the proposed repairs. They used STAGSC-1, a NASA structural analysis program with geometric and nonlinear buckling analysis. The program allowed engineers to determine the deflected and buckling shapes of the structural elements. They could then view the proposed repairs under the pressure that caused the original collapse.
Lin, Naibo; Liu, Xiang Yang
2015-11-01
This review examines how the concepts and ideas of crystallization can be extended further and applied to the field of mesoscopic soft materials. It concerns the structural characteristics vs. the macroscopic performance, and the formation mechanism of crystal networks. Although this subject can be discussed in a broad sense across the area of mesoscopic soft materials, our main focus is on supramolecular materials, spider and silkworm silks, and biominerals. First, the occurrence of a hierarchical structure, i.e. crystal network and domain network structures, will facilitate the formation kinetics of mesoscopic phases and boost up the macroscopic performance of materials in some cases (i.e. spider silk fibres). Second, the structure and performance of materials can be correlated in some way by the four factors: topology, correlation length, symmetry/ordering, and strength of association of crystal networks. Moreover, four different kinetic paths of crystal network formation are identified, namely, one-step process of assembly, two-step process of assembly, mixed mode of assembly and foreign molecule mediated assembly. Based on the basic mechanisms of crystal nucleation and growth, the formation of crystal networks, such as crystallographic mismatch (or noncrystallographic) branching (tip branching and fibre side branching) and fibre/polymeric side merging, are reviewed. This facilitates the rational design and construction of crystal networks in supramolecular materials. In this context, the (re-)construction of a hierarchical crystal network structure can be implemented by thermal, precipitate, chemical, and sonication stimuli. As another important class of soft materials, the unusual mechanical performance of spider and silkworm silk fibres are reviewed in comparison with the regenerated silk protein derivatives. It follows that the considerably larger breaking stress and unusual breaking strain of spider silk fibres vs. silkworm silk fibres can be interpreted
Lin, Naibo; Liu, Xiang Yang
2015-11-01
This review examines how the concepts and ideas of crystallization can be extended further and applied to the field of mesoscopic soft materials. It concerns the structural characteristics vs. the macroscopic performance, and the formation mechanism of crystal networks. Although this subject can be discussed in a broad sense across the area of mesoscopic soft materials, our main focus is on supramolecular materials, spider and silkworm silks, and biominerals. First, the occurrence of a hierarchical structure, i.e. crystal network and domain network structures, will facilitate the formation kinetics of mesoscopic phases and boost up the macroscopic performance of materials in some cases (i.e. spider silk fibres). Second, the structure and performance of materials can be correlated in some way by the four factors: topology, correlation length, symmetry/ordering, and strength of association of crystal networks. Moreover, four different kinetic paths of crystal network formation are identified, namely, one-step process of assembly, two-step process of assembly, mixed mode of assembly and foreign molecule mediated assembly. Based on the basic mechanisms of crystal nucleation and growth, the formation of crystal networks, such as crystallographic mismatch (or noncrystallographic) branching (tip branching and fibre side branching) and fibre/polymeric side merging, are reviewed. This facilitates the rational design and construction of crystal networks in supramolecular materials. In this context, the (re-)construction of a hierarchical crystal network structure can be implemented by thermal, precipitate, chemical, and sonication stimuli. As another important class of soft materials, the unusual mechanical performance of spider and silkworm silk fibres are reviewed in comparison with the regenerated silk protein derivatives. It follows that the considerably larger breaking stress and unusual breaking strain of spider silk fibres vs. silkworm silk fibres can be interpreted
NASA Astrophysics Data System (ADS)
Heuer, Andreas
2008-09-01
In this review a systematic analysis of the potential energy landscape (PEL) of glass-forming systems is presented. Starting from the thermodynamics, the route towards the dynamics is elucidated. A key step in this endeavor is the concept of metabasins. The relevant energy scales of the PEL can be characterized. Based on the simulation results for some glass-forming systems one can formulate a relevant model system (ideal Gaussian glass-former) which can be treated analytically. The macroscopic transport can be related to the microscopic hopping processes, using either the strong relation between energy (thermodynamics) and waiting times (dynamics) or, alternatively, the concepts of the continuous-time random walk. The relation to the geometric properties of the PEL is stressed. The emergence of length scales within the PEL approach as well as the nature of finite-size effects is discussed. Furthermore, the PEL view is compared to other approaches describing the glass transition.
ERIC Educational Resources Information Center
Burson, Kristen M.; Schlexer, Philomena; Bu¨chner, Christin; Lichtenstein, Leonid; Heyde, Markus; Freund, Hans-Joachim
2015-01-01
A two-part experiment using bubble rafts to analyze amorphous structures is presented. In the first part, the distinctions between crystalline and vitreous structures are examined. In the second part, the interface between crystalline and amorphous regions is considered. Bubble rafts are easy to produce and provide excellent analogy to recent…
Stichel, T; Hecht, B; Steenhusen, S; Houbertz, R; Sextl, G
2016-09-15
The two-photon photopolymerization of resins by focused laser light in principle enables the fabrication of structures with details below the diffraction limit. However, the method can be highly susceptible to aberrations, which hinders the fabrication of structures that are larger than, e.g., the working distance of the microscope objective. Here, two-photon polymerization is extended to the fabrication of macroscopic structures by making use of medium numerical-aperture microscope objectives. By introducing a substrate holder movable in the axial direction it is possible to keep the focusing conditions constant and to fabricate very large structures with heights that are not limited by the working distance of the objective. Moreover, the constant focusing conditions enable us to quantify spherical aberrations by experimental mapping of the optical point-spread function, which manifests itself in the shape of singe photo-polymerized voxels. By monitoring such shapes it is possible to minimize aberrations. Effective aberration control enables us to fabricate large but detailed biomedical scaffolds with interconnected pores, e.g., in the shape of a human stirrup bone.
Wu, Zi Liang; Kurokawa, Takayuki; Liang, Songmiao; Furukawa, Hidemitsu; Gong, Jian Ping
2010-07-28
A hydrogel with cylindrically symmetric structure at macroscopic scale has been developed by polymerization of a cationic monomer in the presence of a small amount of semi-rigid polyanion poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT) in a cylinder glass tube. The polyion complex radially aligns in the outer region of the synthesized cylinder gel. On the other hand, it orients in concentric and axial directions in the inner region. To the authors' knowledge, this is the first report of such millimeter-scale ordered structure developed in a polymeric hydrogel. We elucidate that homeotropic alignment on the glass wall is energetically favorable for the semi-rigid polyion complex, resulting in the radial orientation in the outer region. In the inner region, the oriented structures result from the monomer difffusion (due to the heterogeneous polymerization) that induces PBDT orientation perpendicular to the diffusion direction. The structured gels showing sensitive response of birefringence to external force are expected to find applications in optical sensors. PMID:20590113
Stichel, T; Hecht, B; Steenhusen, S; Houbertz, R; Sextl, G
2016-09-15
The two-photon photopolymerization of resins by focused laser light in principle enables the fabrication of structures with details below the diffraction limit. However, the method can be highly susceptible to aberrations, which hinders the fabrication of structures that are larger than, e.g., the working distance of the microscope objective. Here, two-photon polymerization is extended to the fabrication of macroscopic structures by making use of medium numerical-aperture microscope objectives. By introducing a substrate holder movable in the axial direction it is possible to keep the focusing conditions constant and to fabricate very large structures with heights that are not limited by the working distance of the objective. Moreover, the constant focusing conditions enable us to quantify spherical aberrations by experimental mapping of the optical point-spread function, which manifests itself in the shape of singe photo-polymerized voxels. By monitoring such shapes it is possible to minimize aberrations. Effective aberration control enables us to fabricate large but detailed biomedical scaffolds with interconnected pores, e.g., in the shape of a human stirrup bone. PMID:27628374
Designing ‘Smart’ Particles for the Assembly of Complex Macroscopic Structures**
Barg, S.; Bell, R.; Weaver, J.; Walter, C.; Goyos, L.; Saiz, E.
2013-01-01
Surface functionalization with a branched copolymer surfactant is used to create responsive inorganic particles that can self-assemble in complex structures. The assembly process is triggered by a pH switch that reversibly activates multiple hydrogen bonds between ceramic particles and soft templates. PMID:23780923
NASA Astrophysics Data System (ADS)
Tune, Travis; Irving, Tom; Sponberg, Simon
Muscle is a unique hierarchical material composed of millions of molecular motors arranged on filaments in a regular lattice structure. The macroscopic, material behavior of muscle can be characterized by its workloop, a periodically activated force-length curve. Muscle is capable of operating as a spring, motor, brake, or strut, defined by its workloop. We are interested in the multiscale physics of muscle that drive its ``energetic versatility'' - the ability of muscle to alter its function. Here we introduce a system of two muscles from the cockroach whose workloops are not explained by our current understanding of the determinants of workloop function (the classic force-length, force-velocity, and twitch response). Differences in material behavior may arise from structural differences in the muscle's active lattice. Using the BIOCat beam at the Advanced Photon Source at Argonne NL, we tested for differences in the two muscles' lattice structure. Small-angle x-ray scattering (SAXS) revealed a difference of 4-8
Gustafsson, Emil; Hedberg, Jonas; Larsson, Per A; Wågberg, Lars; Johnson, C Magnus
2015-04-21
Adsorption of a single layer of molecules on a surface, or even a reorientation of already present molecules, can significantly affect the surface properties of a material. In this study, vibrational sum frequency spectroscopy (VSFS) has been used to study the change in molecular structure at the solid-air interface following thermal curing of polyelectrolyte multilayers of poly(allylamine hydrochloride) and poly(acrylic acid). Significant changes in the VSF spectra were observed after curing. These changes were accompanied by a distinct increase in the static water contact angle, showing how the properties of the layer-by-layer molecular structure are controlled not just by the polyelectrolyte in the outermost layer but ultimately by the orientation of the chemical constituents in the outermost layers. PMID:25859709
Wolthers, M; Di Tommaso, D; Du, Z; de Leeuw, N H
2012-11-21
Calcite-water interactions are important not only in carbon sequestration and the global carbon cycle, but also in contaminant behaviour in calcite-bearing host rock and in many industrial applications. Here we quantify the effect of variations in surface structure on calcite surface reactivity. Firstly, we employ classical Molecular Dynamics simulations of calcite surfaces containing an etch pit and a growth terrace, to show that the local environment in water around structurally different surface sites is distinct. In addition to observing the expected formation of more calcium-water interactions and hydrogen-bonds at lower-coordinated sites, we also observed subtle differences in hydrogen bonding around acute versus obtuse edges and corners. We subsequently used this information to refine the protonation constants for the calcite surface sites, according to the Charge Distribution MUltiSite Ion Complexation (CD-MUSIC) approach. The subtle differences in hydrogen bonding translate into markedly different charging behaviour versus pH, in particular for acute versus obtuse corner sites. The results show quantitatively that calcite surface reactivity is directly related to surface topography. The information obtained in this study is not only crucial for the improvement of existing macroscopic surface models of the reactivity of calcite towards contaminants, but also improves our atomic-level understanding of mineral-water interactions.
Topp, Kimberly S; Boyd, Benjamin S
2012-01-01
Peripheral nerves are composed of motor and sensory axons, associated ensheathing Schwann cells, and organized layers of connective tissues that are in continuity with the tissues of the central nervous system. Nerve fiber anatomy facilitates conduction of electrical impulses to convey information over a distance, and the length of these polarized cells necessitates regulated axonal transport of organelles and structural proteins for normal cell function. Nerve connective tissues serve a protective function as the limb is subjected to the stresses of myriad limb positions and postures. Thus, the tissues are uniquely arranged to control the local nerve fiber environment and modulate physical stresses. In this brief review, we describe the microscopic anatomy and physiology of peripheral nerve and the biomechanical properties that enable nerve to withstand the physical stresses of everyday life. PMID:22133662
Nogueira-Melo, Georgea Santos; Santos, Paulo Jorge Parreira; Gibertoni, Tatiana Baptista
2014-12-01
Mangroves are transitional ecosystems between terrestrial and marine environments, and are dis- tinguished by a high abundance of animals, plants, and fungi. Although macrofungi occur in different types of habitat, including mangroves, little is known about their community structure and dynamic. Therefore the aim of this study was to analyze the diversity of macrofungi in a number of Brazilian mangroves, and the relation- ship between such diversity, precipitation and area of collection. A total of 32 field trips were undertaken from 2009 to 2010, and macrofungi were studied in four 250 x 40 m transects: Timbó and Santa Cruz Channel on the Northern coast, and Maracaipe and Ariquindá on the Southern coast. All basidiomata found along the transects were placed in paper bags, air-dried and identified using existing literature. It was found that Northern areas predominantly featured Avicennia schaueriana mangroves, while Rhizophora mangle dominated in Southern transects. A total of 275 specimens were collected, and 33 species, 28 genera, 14 families and six orders were represented. Overall abundance and species richness did not vary significantly among areas, but varied according to time, being higher during the rainy season. Subtle differences in composition were observed over time and between areas, probably due to variations in plant species occurrence. Further studies with collections during months of greater precipitation in transects dominated by different mangrove species of the same ecosystem are suggested to assess the overall diversity of mycobiota in these ecosystems. PMID:25720189
Nogueira-Melo, Georgea Santos; Santos, Paulo Jorge Parreira; Gibertoni, Tatiana Baptista
2014-12-01
Mangroves are transitional ecosystems between terrestrial and marine environments, and are dis- tinguished by a high abundance of animals, plants, and fungi. Although macrofungi occur in different types of habitat, including mangroves, little is known about their community structure and dynamic. Therefore the aim of this study was to analyze the diversity of macrofungi in a number of Brazilian mangroves, and the relation- ship between such diversity, precipitation and area of collection. A total of 32 field trips were undertaken from 2009 to 2010, and macrofungi were studied in four 250 x 40 m transects: Timbó and Santa Cruz Channel on the Northern coast, and Maracaipe and Ariquindá on the Southern coast. All basidiomata found along the transects were placed in paper bags, air-dried and identified using existing literature. It was found that Northern areas predominantly featured Avicennia schaueriana mangroves, while Rhizophora mangle dominated in Southern transects. A total of 275 specimens were collected, and 33 species, 28 genera, 14 families and six orders were represented. Overall abundance and species richness did not vary significantly among areas, but varied according to time, being higher during the rainy season. Subtle differences in composition were observed over time and between areas, probably due to variations in plant species occurrence. Further studies with collections during months of greater precipitation in transects dominated by different mangrove species of the same ecosystem are suggested to assess the overall diversity of mycobiota in these ecosystems.
NASA Astrophysics Data System (ADS)
Yang, Wenchao; Yao, Yao; Wu, Chang-Qin
2015-04-01
In the currently popular organic-inorganic hybrid perovskite solar cells, the slowness of the charge recombination processes is found to be a key factor for contributing to their high efficiencies and high open circuit voltages, but the underlying recombination mechanism remains unclear. In this work, we investigate the bimolecular recombination (BR) and the trap-assisted monomolecular recombination (MR) in meso-structured perovskite solar cells under steady state working condition, and try to reveal their roles on determining the device performance. Some interfacial effects such as the injection barriers at the selective contacts are examined as well. Based on the macroscopic device modeling, the recombination resistance-voltage (Rrec-V) and the current density-voltage (J-V) curves are calculated to characterize the recombination mechanism and describe the device performance, respectively. Through comparison with the impedance spectroscopy extracted Rrec data, it is found that under the typical BR reduction factor and deep trap densities observed in experiments, the MR dominates the charge recombination in the low voltage regime, while the BR dominates in the high voltage regime. The short circuit current and the fill factor could be reduced by the significant MR but the open circuit voltage is generally determined by the BR. The different electron injection barriers at the contact can change the BR rate and induce different patterns for the Rrec-V characteristics. For the perovskites of increased band gaps, the Rrec's are significantly enhanced, corresponding to the high open circuit voltages. Finally, it is revealed that the reduced effective charge mobility due to the transport in electron and hole transporting material makes the Rrec decrease slowly with the increasing voltage, which leads to increased open circuit voltage.
Axnér, E; Holm, D; Gavier-Widén, D; Söderberg, A; Bergqvist, A S
2015-09-15
Although monitoring wild animals in the field is essential for estimations of population size and development, there are pitfalls associated with field monitoring. In addition, some detailed data about reproductive physiology can be difficult to obtain in wild live animals. Studying reproductive organs from the Eurasian lynx killed at hunting or found dead could be used as a valuable addition to other field data. We evaluated reproductive organs from 39 Eurasian lynx females (Lynx lynx) killed in Sweden during the hunting seasons in 2009, 2010, and 2011. According to notes on ovarian structures, the animals were categorized as being in one of four different reproductive stages: juvenile (n = 10), follicular stage (n = 8), luteal stage (n = 11), and anestrus (n = 10). Corpora lutea were classified as fresh CL from the present season or as luteal bodies from previous cycles. Microscopic evaluations were blindly coded while the outer measurements of the vagina and uterus were taken at the time of organ retrieval. The width of the endometrium, myometrium, outer width of the uterine horns, and the diameter of the vagina differed significantly with the reproductive stage (P < 0.001) and were largest in the follicular and luteal phases. The number of endometrial glands evaluated blindly coded on a subjective scale was significantly associated with the reproductive stage (P < 0.0001) and was significantly higher in the luteal phase than that in any other reproductive stages (P < 0.05). Cornification of the vaginal epithelium was only observed in females in the follicular stage or in females with signs of a recent ovulation. In conclusion, both macroscopic and histologic measurements are useful for a correct classification of the reproductive stage when evaluating reproductive organs in the Eurasian lynx killed during the hunting season. Routine evaluation of reproductive organs has a potential to be a useful additional tool to field studies of live lynx to monitor their
Axnér, E; Holm, D; Gavier-Widén, D; Söderberg, A; Bergqvist, A S
2015-09-15
Although monitoring wild animals in the field is essential for estimations of population size and development, there are pitfalls associated with field monitoring. In addition, some detailed data about reproductive physiology can be difficult to obtain in wild live animals. Studying reproductive organs from the Eurasian lynx killed at hunting or found dead could be used as a valuable addition to other field data. We evaluated reproductive organs from 39 Eurasian lynx females (Lynx lynx) killed in Sweden during the hunting seasons in 2009, 2010, and 2011. According to notes on ovarian structures, the animals were categorized as being in one of four different reproductive stages: juvenile (n = 10), follicular stage (n = 8), luteal stage (n = 11), and anestrus (n = 10). Corpora lutea were classified as fresh CL from the present season or as luteal bodies from previous cycles. Microscopic evaluations were blindly coded while the outer measurements of the vagina and uterus were taken at the time of organ retrieval. The width of the endometrium, myometrium, outer width of the uterine horns, and the diameter of the vagina differed significantly with the reproductive stage (P < 0.001) and were largest in the follicular and luteal phases. The number of endometrial glands evaluated blindly coded on a subjective scale was significantly associated with the reproductive stage (P < 0.0001) and was significantly higher in the luteal phase than that in any other reproductive stages (P < 0.05). Cornification of the vaginal epithelium was only observed in females in the follicular stage or in females with signs of a recent ovulation. In conclusion, both macroscopic and histologic measurements are useful for a correct classification of the reproductive stage when evaluating reproductive organs in the Eurasian lynx killed during the hunting season. Routine evaluation of reproductive organs has a potential to be a useful additional tool to field studies of live lynx to monitor their
Yang, Wenchao; Yao, Yao Wu, Chang-Qin
2015-04-21
In the currently popular organic-inorganic hybrid perovskite solar cells, the slowness of the charge recombination processes is found to be a key factor for contributing to their high efficiencies and high open circuit voltages, but the underlying recombination mechanism remains unclear. In this work, we investigate the bimolecular recombination (BR) and the trap-assisted monomolecular recombination (MR) in meso-structured perovskite solar cells under steady state working condition, and try to reveal their roles on determining the device performance. Some interfacial effects such as the injection barriers at the selective contacts are examined as well. Based on the macroscopic device modeling, the recombination resistance-voltage (R{sub rec}−V) and the current density-voltage (J–V) curves are calculated to characterize the recombination mechanism and describe the device performance, respectively. Through comparison with the impedance spectroscopy extracted R{sub rec} data, it is found that under the typical BR reduction factor and deep trap densities observed in experiments, the MR dominates the charge recombination in the low voltage regime, while the BR dominates in the high voltage regime. The short circuit current and the fill factor could be reduced by the significant MR but the open circuit voltage is generally determined by the BR. The different electron injection barriers at the contact can change the BR rate and induce different patterns for the R{sub rec}–V characteristics. For the perovskites of increased band gaps, the R{sub rec}'s are significantly enhanced, corresponding to the high open circuit voltages. Finally, it is revealed that the reduced effective charge mobility due to the transport in electron and hole transporting material makes the R{sub rec} decrease slowly with the increasing voltage, which leads to increased open circuit voltage.
Jha, Amit K.; Malik, Manisha S.; Farach-Carson, Mary C.; Duncan, Randall L.; Jia, Xinqiao
2010-01-01
We aimed to develop biomimetic hydrogel matrices that not only exhibit structural hierarchy and mechanical integrity, but also present biological cues in a controlled fashion. To this end, photocrosslinkable, hyaluronic acid (HA)-based hydrogel particles (HGPs) were synthesized via an inverse emulsion crosslinking process followed by chemical modification with glycidyl methacrylate (GMA). HA modified with GMA (HA-GMA) was employed as the soluble macromer. Macroscopic hydrogels containing covalently integrated hydrogel particles (HA-c-HGP) were prepared by radical polymerization of HA-GMA in the presence of crosslinkable HGPs. The covalent linkages between the hydrogel particles and the secondary HA matrix resulted in the formation of a diffuse, fibrilar interface around the particles. Compared to the traditional bulk gels synthesized by photocrosslinking of HA-GMA, these hydrogels exhibited a reduced sol fraction and a lower equilibrium swelling ratio. When tested under uniaxial compression, the HA-c-HGP gels were more pliable than the HA-p-HGP gels and fractured at higher strain than the HA-GMA gels. Primary bovine chondrocytes were photoencapsulated in the HA matrices with minimal cell damage. The 3D microenvironment created by HA-GMA and HA HGPs not only maintained the chondrocyte phenotype but also fostered the production of cartilage specific extracellular matrix. To further improve the biological activities of the HA-c-HGP gels, bone morphogenetic protein 2 (BMP-2) was loaded into the immobilized HGPs. BMP-2 was released from the HA-c-HGP gels in a controlled manner with reduced initial burst over prolonged periods of time. The HA-c-HGP gels are promising candidates for use as bioactive matrices for cartilage tissue engineering. PMID:20936090
Macroscopic and microscopic aspects in nuclear fission
NASA Astrophysics Data System (ADS)
Strutinsky, V.
1989-10-01
Nuclear macroscopic properties are determined as statistical averages and it is then recognized that several levels of macroscopic descriptions may exist. By zooming the averaging scale the gross shell structures are distinguished from the macroscopic background and a theory can be formed consistently combining both the macroscopic and microscopic features. The shell structure varies in the fissioning nucleus on its way to scission leading to a double-humped shape of the fission barrier. This is due to modifications of the classical periodic paths responsible for the quantal non-uniformity of the single-particle phase space. Briefly results of the combined theory for the fission process are outlined.
Rukmangadachar, Lokesh A.; Makharia, Govind K.; Mishra, Asha; Das, Prasenjit; Hariprasad, Gururao; Srinivasan, Alagiri; Gupta, Siddhartha Datta; Ahuja, Vineet; Acharya, Subrat K.
2016-01-01
Differentiation between intestinal tuberculosis (ITB) and Crohn’s disease (CD) is challenging in geographical regions where both these diseases are prevalent. There is a need of biomarkers for differentiation between these two disorders. Colonic biopsies from inflamed mucosa of treatment-naive patients with ITB, CD and controls were used for analysis. Protein extracted from biopsies was digested with trypsin and resulting peptides were labeled with iTRAQ reagents. The peptides were subsequently analyzed using LC-MS/MS for identification and quantification. Gene ontology annotation for proteins was analyzed in PANTHER. Validation experiments were done for six differentially expressed proteins using immunohistochemistry. 533 proteins were identified and 241 proteins were quantified from 5 sets of iTRAQ experiments. While 63 were differentially expressed in colonic mucosa of patients with CD and ITB in at least one set of iTRAQ experiment, 11 proteins were differentially expressed in more than one set of experiments. Six proteins used for validation using immunohistochemistry in a larger cohort of patients; none of them however was differentially expressed in patients with ITB and CD. There are differentially expressed proteins in tissue proteome of CD and ITB. Further experiments are required using a larger cohort of homogeneous tissue samples. PMID:26988818
NASA Astrophysics Data System (ADS)
Meyer, Daniel W.; Bijeljic, Branko
2016-07-01
We devise an efficient methodology to provide a universal statistical description of advection-dominated dispersion (Péclet→∞ ) in natural porous media including carbonates. First, we investigate the dispersion of tracer particles by direct numerical simulation (DNS). The transverse dispersion is found to be essentially determined by the tortuosity and it approaches a Fickian limit within a dozen characteristic scales. Longitudinal dispersion was found to be Fickian in the limit for bead packs and superdiffusive for all other natural media inspected. We demonstrate that the Lagrangian velocity correlation length is a quantity that characterizes the spatial variability for transport. Finally, a statistical transport model is presented that sheds light on the connection between pore-scale characteristics and the resulting macroscopic transport behavior. Our computationally efficient model accurately reproduces the transport behavior in longitudinal direction and approaches the Fickian limit in transverse direction.
NASA Astrophysics Data System (ADS)
Boffy, R.; Peuget, S.; Schweins, R.; Beaucour, J.; Bermejo, F. J.
2016-05-01
The behaviour of four alkali-borosilicate glasses under homogeneous thermal neutron irradiation has been studied. These materials are used for the manufacturing of neutron guides which are installed in most facilities as devices to transport neutrons from intense sources such as nuclear reactors or spallation sources up to scientific instruments. Several experimental techniques such as Raman, NMR, SANS and STEM have been employed in order to understand the rather different macroscopic behaviour under irradiation of materials that belong to a same glass family. The results have shown that the remarkable glass shrinking observed for neutron doses below 0.5 ·1018 n/cm2 critically depends upon the presence of domains where silicate and borate network do not mix.
Meyer, Daniel W; Bijeljic, Branko
2016-07-01
We devise an efficient methodology to provide a universal statistical description of advection-dominated dispersion (Péclet→∞) in natural porous media including carbonates. First, we investigate the dispersion of tracer particles by direct numerical simulation (DNS). The transverse dispersion is found to be essentially determined by the tortuosity and it approaches a Fickian limit within a dozen characteristic scales. Longitudinal dispersion was found to be Fickian in the limit for bead packs and superdiffusive for all other natural media inspected. We demonstrate that the Lagrangian velocity correlation length is a quantity that characterizes the spatial variability for transport. Finally, a statistical transport model is presented that sheds light on the connection between pore-scale characteristics and the resulting macroscopic transport behavior. Our computationally efficient model accurately reproduces the transport behavior in longitudinal direction and approaches the Fickian limit in transverse direction. PMID:27575217
ERIC Educational Resources Information Center
Rahayu, Sri; Kita, Masakazu
2010-01-01
This study investigated Indonesian and Japanese students' understandings of macroscopic and submicroscopic levels of representing matter and its changes and the difficulties they have with these concepts. A multiple-choice questionnaire was constructed and delivered to 447 Indonesian and 446 Japanese public senior high school students. The data…
Noffke, Nora
2015-02-01
Sandstone beds of the <3.7 Ga Gillespie Lake Member on Mars have been interpreted as evidence of an ancient playa lake environment. On Earth, such environments have been sites of colonization by microbial mats from the early Archean to the present time. Terrestrial microbial mats in playa lake environments form microbialites known as microbially induced sedimentary structures (MISS). On Mars, three lithofacies of the Gillespie Lake Member sandstone display centimeter- to meter-scale structures similar in macroscopic morphology to terrestrial MISS that include "erosional remnants and pockets," "mat chips," "roll-ups," "desiccation cracks," and "gas domes." The microbially induced sedimentary-like structures identified in Curiosity rover mission images do not have a random distribution. Rather, they were found to be arranged in spatial associations and temporal successions that indicate they changed over time. On Earth, if such MISS occurred with this type of spatial association and temporal succession, they would be interpreted as having recorded the growth of a microbially dominated ecosystem that thrived in pools that later dried completely: erosional pockets, mat chips, and roll-ups resulted from water eroding an ancient microbial mat-covered sedimentary surface; during the course of subsequent water recess, channels would have cut deep into the microbial mats, leaving erosional remnants behind; desiccation cracks and gas domes would have occurred during a final period of subaerial exposure of the microbial mats. In this paper, the similarities of the macroscopic morphologies, spatial associations, and temporal succession of sedimentary structures on Mars to MISS preserved on Earth has led to the following hypothesis: The sedimentary structures in the <3.7 Ga Gillespie Lake Member on Mars are ancient MISS produced by interactions between microbial mats and their environment. Proposed here is a strategy for detecting, identifying, confirming, and differentiating
Noffke, Nora
2015-02-01
Sandstone beds of the <3.7 Ga Gillespie Lake Member on Mars have been interpreted as evidence of an ancient playa lake environment. On Earth, such environments have been sites of colonization by microbial mats from the early Archean to the present time. Terrestrial microbial mats in playa lake environments form microbialites known as microbially induced sedimentary structures (MISS). On Mars, three lithofacies of the Gillespie Lake Member sandstone display centimeter- to meter-scale structures similar in macroscopic morphology to terrestrial MISS that include "erosional remnants and pockets," "mat chips," "roll-ups," "desiccation cracks," and "gas domes." The microbially induced sedimentary-like structures identified in Curiosity rover mission images do not have a random distribution. Rather, they were found to be arranged in spatial associations and temporal successions that indicate they changed over time. On Earth, if such MISS occurred with this type of spatial association and temporal succession, they would be interpreted as having recorded the growth of a microbially dominated ecosystem that thrived in pools that later dried completely: erosional pockets, mat chips, and roll-ups resulted from water eroding an ancient microbial mat-covered sedimentary surface; during the course of subsequent water recess, channels would have cut deep into the microbial mats, leaving erosional remnants behind; desiccation cracks and gas domes would have occurred during a final period of subaerial exposure of the microbial mats. In this paper, the similarities of the macroscopic morphologies, spatial associations, and temporal succession of sedimentary structures on Mars to MISS preserved on Earth has led to the following hypothesis: The sedimentary structures in the <3.7 Ga Gillespie Lake Member on Mars are ancient MISS produced by interactions between microbial mats and their environment. Proposed here is a strategy for detecting, identifying, confirming, and differentiating
Nielen, Michel W F; van Beek, Teris A
2014-11-01
Laser-ablation electrospray ionization (LAESI) mass spectrometry imaging (MSI) does not require very flat surfaces, high-precision sample preparation, or the addition of matrix. Because of these features, LAESI-MSI may be the method of choice for spatially-resolved food analysis. In this work, LAESI time-of-flight MSI was investigated for macroscopic and microscopic imaging of pesticides, mycotoxins, and plant metabolites on rose leaves, orange and lemon fruit, ergot bodies, cherry tomatoes, and maize kernels. Accurate mass ion-map data were acquired at sampling locations with an x-y center-to-center distance of 0.2-1.0 mm and were superimposed onto co-registered optical images. The spatially-resolved ion maps of pesticides on rose leaves suggest co-application of registered and banned pesticides. Ion maps of the fungicide imazalil reveal that this compound is only localized on the peel of citrus fruit. However, according to three-dimensional LAESI-MSI the penetration depth of imazalil into the peel has significant local variation. Ion maps of different plant alkaloids on ergot bodies from rye reveal co-localization in accordance with expectations. The feasibility of using untargeted MSI for food analysis was revealed by ion maps of plant metabolites in cherry tomatoes and maize-kernel slices. For tomatoes, traveling-wave ion mobility (TWIM) was used to discriminate between different lycoperoside glycoalkaloid isomers; for maize quadrupole time-of-flight tandem mass spectrometry (MS-MS) was successfully used to elucidate the structure of a localized unknown. It is envisaged that LAESI-MSI will contribute to future research in food science, agriforensics, and plant metabolomics. PMID:24961635
NASA Astrophysics Data System (ADS)
Kitano, H.; Ota, K.; Hamada, K.; Takemura, R.; Ohmaki, M.; Maeda, A.; Suzuki, M.
2009-03-01
A nanometer-thick small mesa consiting of only two or three Bi2Sr2CaCu2Oy intrinsic Josephson junctions (IJJs) is studied through the switching current distribution measurements down to 0.4 K. Experimental results clearly show that the first switching events from the zero-voltage state for 1 K < T < 4 K are successfully described by a conventional thermal activation (TA) theory for a single Josephson junction, and that they become independent of temperature below T* ~ 0.7 K. We observe the microwave-induced peak in the switching distribution at 0.4 K, which is induced by the microwave irradiation at 55 GHz. These results strongly suggest that the system crossovers to macroscopic quantum tunneling (MQT) regime below T*, which is as high as the previously reported value for a stacked IJJs with several tens of junctions, in contrast to the recent result on a similar mesa-structured surface IJJ.
Buckling of regular, chiral and hierarchical honeycombs under a general macroscopic stress state
Haghpanah, Babak; Papadopoulos, Jim; Mousanezhad, Davood; Nayeb-Hashemi, Hamid; Vaziri, Ashkan
2014-01-01
An approach to obtain analytical closed-form expressions for the macroscopic ‘buckling strength’ of various two-dimensional cellular structures is presented. The method is based on classical beam-column end-moment behaviour expressed in a matrix form. It is applied to sample honeycombs with square, triangular and hexagonal unit cells to determine their buckling strength under a general macroscopic in-plane stress state. The results were verified using finite-element Eigenvalue analysis. PMID:25002823
NASA Astrophysics Data System (ADS)
Schneider, Ling; Laustsen, Milan; Mandsberg, Nikolaj; Taboryski, Rafael
2016-02-01
We discuss the influence of surface structure, namely the height and opening angles of nano- and microcones on the surface wettability. We show experimental evidence that the opening angle of the cones is the critical parameter on sample superhydrophobicity, namely static contact angles and roll-off angles. The textured surfaces are fabricated on silicon wafers by using a simple one-step method of reactive ion etching at different processing time and gas flow rates. By using hydrophobic coating or hydrophilic surface treatment, we are able to switch the surface wettability from superhydrophilic to superhydrophobic without altering surface structures. In addition, we show examples of polymer replicas (polypropylene and poly(methyl methacrylate) with different wettability, fabricated by injection moulding using templates of the silicon cone-structures.
Schneider, Ling; Laustsen, Milan; Mandsberg, Nikolaj; Taboryski, Rafael
2016-01-01
We discuss the influence of surface structure, namely the height and opening angles of nano- and microcones on the surface wettability. We show experimental evidence that the opening angle of the cones is the critical parameter on sample superhydrophobicity, namely static contact angles and roll-off angles. The textured surfaces are fabricated on silicon wafers by using a simple one-step method of reactive ion etching at different processing time and gas flow rates. By using hydrophobic coating or hydrophilic surface treatment, we are able to switch the surface wettability from superhydrophilic to superhydrophobic without altering surface structures. In addition, we show examples of polymer replicas (polypropylene and poly(methyl methacrylate) with different wettability, fabricated by injection moulding using templates of the silicon cone-structures. PMID:26892169
NASA Astrophysics Data System (ADS)
Wichtowski, Marek; Ziółkowski, Andrzej
2016-09-01
The validity of the commonly used time-dependent wave equation describing the propagation of screening one-dimensional solitons in photorefractive materials is discussed. Concentrating attention on temporal development of the space-charge field, we show that the widely used standard solution follows from a phenomenological description, which is consistent with the band transport model equations only in specific cases. The exact analytical solution for the localized optical beam is derived within the microscopic model under a low contrast approximation. The numerical modeling of photorefractive response to an arbitrary contrast is performed and compared with standard solutions. The range of applicability of the macroscopic approach for three basic classes of photorefractive crystals is discussed.
NASA Technical Reports Server (NTRS)
1984-01-01
Nonlinear structural analysis techniques for engine structures and components are addressed. The finite element method and boundary element method are discussed in terms of stress and structural analyses of shells, plates, and laminates.
Rank distributions: A panoramic macroscopic outlook
NASA Astrophysics Data System (ADS)
Eliazar, Iddo I.; Cohen, Morrel H.
2014-01-01
This paper presents a panoramic macroscopic outlook of rank distributions. We establish a general framework for the analysis of rank distributions, which classifies them into five macroscopic "socioeconomic" states: monarchy, oligarchy-feudalism, criticality, socialism-capitalism, and communism. Oligarchy-feudalism is shown to be characterized by discrete macroscopic rank distributions, and socialism-capitalism is shown to be characterized by continuous macroscopic size distributions. Criticality is a transition state between oligarchy-feudalism and socialism-capitalism, which can manifest allometric scaling with multifractal spectra. Monarchy and communism are extreme forms of oligarchy-feudalism and socialism-capitalism, respectively, in which the intrinsic randomness vanishes. The general framework is applied to three different models of rank distributions—top-down, bottom-up, and global—and unveils each model's macroscopic universality and versatility. The global model yields a macroscopic classification of the generalized Zipf law, an omnipresent form of rank distributions observed across the sciences. An amalgamation of the three models establishes a universal rank-distribution explanation for the macroscopic emergence of a prevalent class of continuous size distributions, ones governed by unimodal densities with both Pareto and inverse-Pareto power-law tails.
Rank distributions: a panoramic macroscopic outlook.
Eliazar, Iddo I; Cohen, Morrel H
2014-01-01
This paper presents a panoramic macroscopic outlook of rank distributions. We establish a general framework for the analysis of rank distributions, which classifies them into five macroscopic "socioeconomic" states: monarchy, oligarchy-feudalism, criticality, socialism-capitalism, and communism. Oligarchy-feudalism is shown to be characterized by discrete macroscopic rank distributions, and socialism-capitalism is shown to be characterized by continuous macroscopic size distributions. Criticality is a transition state between oligarchy-feudalism and socialism-capitalism, which can manifest allometric scaling with multifractal spectra. Monarchy and communism are extreme forms of oligarchy-feudalism and socialism-capitalism, respectively, in which the intrinsic randomness vanishes. The general framework is applied to three different models of rank distributions-top-down, bottom-up, and global-and unveils each model's macroscopic universality and versatility. The global model yields a macroscopic classification of the generalized Zipf law, an omnipresent form of rank distributions observed across the sciences. An amalgamation of the three models establishes a universal rank-distribution explanation for the macroscopic emergence of a prevalent class of continuous size distributions, ones governed by unimodal densities with both Pareto and inverse-Pareto power-law tails. PMID:24580176
NASA Astrophysics Data System (ADS)
Ota, K.; Hamada, K.; Takemura, R.; Ohmaki, M.; Machi, T.; Tanabe, K.; Suzuki, M.; Maeda, A.; Kitano, H.
2009-04-01
We investigated macroscopic quantum tunneling (MQT) of Bi2Sr2CaCu2Oy intrinsic Josephson junctions (IJJs) for two device structures. One is a small mesa, which is a few nanometers thick with only two or three IJJs, and the other is a stack of a few hundred IJJs in a narrow bridge structure. The experimental results regarding the switching-current distribution for the first switch from the zero-voltage state were in good agreement with the conventional theory for a single Josephson junction, indicating that the crossover temperature from thermal activation to the MQT regime for the former device structure was similar to that for the latter device structure. Together with the observation of multiphoton transitions between quantized energy levels in the MQT regime, these results strongly suggest that the observed MQT behavior is intrinsic to a single IJJ in high- Tc cuprates and is independent of the device structure. The switching-current distribution for the second switch from the first resistive state, which was carefully distinguished from the first switch, was also compared with respect to the two device structures. In spite of the differences between the heat transfer environments, the second switch exhibited a similar temperature-independent behavior for both devices up to a much higher temperature than the crossover temperature for the first switch. We argue that this cannot be explained in terms of self-heating caused by dissipative currents after the first switch. As possible candidates for this phenomenon, the MQT process for the second switch and the effective increase in the electronic temperature due to the quasiparticle injection are discussed.
Nagaoka, Masataka
2015-12-31
A new efficient hybrid Monte Carlo (MC)/molecular dynamics (MD) reaction method with a rare event-driving mechanism is introduced as a practical ‘atomistic’ molecular simulation of large-scale chemically reactive systems. Starting its demonstrative application to the racemization reaction of (R)-2-chlorobutane in N,N-dimethylformamide solution, several other applications are shown from the practical viewpoint of molecular controlling of complex chemical reactions, stereochemistry and aggregate structures. Finally, I would like to mention the future applications of the hybrid MC/MD reaction method.
Smodlaka, H; Henry, R W; Reed, R B
2009-06-01
The ringed seal [Pusa (Phoca) hispida], as well as other seals, exhibits unique anatomical properties when compared to its terrestrial counterparts. In the ringed seal, the most conspicuous marine adaptation is the aortic bulb. This large dilatation of the ascending aorta is comparable to that found in other seal species and marine mammals. The branches of the ascending aorta (brachiocephalic trunk, left common carotid artery and left subclavian artery) are similar to those of higher primates and man. The peculiarities of the venous system are: three pulmonary veins, a pericardial venous plexus, a caval sphincter, a hepatic sinus with paired caudal vena cavae and a large extradural venous plexus. Generally, three common pulmonary veins (right, left and caudal) empty into the left atrium. The pericardial venous plexus lies deep to the mediastinal pericardial pleura (pleura pericardica) on the auricular (ventral) surface of the heart. The caval sphincter surrounds the caudal vena cava as it passes through the diaphragm. Caudal to the diaphragm, the vena cava is dilated (the hepatic sinus), and near the cranial extremity of the kidneys, it becomes biphid. The azygos vein is formed from the union of the right and left azygos veins at the level of the 5th thoracic vertebra. Cardiovascular physiological studies show some of these anatomical variations, especially of the venous system and the ascending aorta, to be modifications for diving. This investigation documents the large blood vessels associated with the heart and related structures in the ringed seal. PMID:19245671
Aerobrake plasmadynamics - Macroscopic effects
NASA Astrophysics Data System (ADS)
Shebalin, John V.
1990-06-01
The flow around an aerobraking spacecraft (such as the Aeroassist Flight Experiment reentry vehicle) will contain a region of partially ionized gas, that is, a plasma. It is shown here by numerical simulation that macroscopic plasmadynamic effects (which are not included in standard aerothermodynamic simulations) will have a noticeable effect on the reentry flow field. In particular, there are thermoelectric phenomena which can have a major influence in flow dynamics at the front of an ionizing bowshock. These thermoelectric phenomena arise because of the presence of large density and temperature gradients at the front of a reentry bowshock, and they include strong local magnetic fields, electric currents, and ohmic heating. One important result is the dramatic increase in temperature (over the case where plasma effects are neglected) at a reentry shock front; the implication is that macroscopic plasmadynamic effects can no longer be neglected in simulations of hypersonic reentry flow fields.
Fernandes, M Marques; Scheinost, A C; Baeyens, B
2016-08-01
The credibility of long-term safety assessments of radioactive waste repositories may be greatly enhanced by a molecular level understanding of the sorption processes onto individual minerals present in the near- and far-fields. In this study we couple macroscopic sorption experiments to surface complexation modelling and spectroscopic investigations, including extended X-ray absorption fine structure (EXAFS) and time-resolved laser fluorescence spectroscopies (TRLFS), to elucidate the uptake mechanism of trivalent lanthanides and actinides (Ln/An(III)) by montmorillonite in the absence and presence of dissolved carbonate. Based on the experimental sorption isotherms for the carbonate-free system, the previously developed 2 site protolysis non electrostatic surface complexation and cation exchange (2SPNE SC/CE) model needed to be complemented with an additional surface complexation reaction onto weak sites. The fitting of sorption isotherms in the presence of carbonate required refinement of the previously published model by reducing the strong site capacity and by adding the formation of Ln/An(III)-carbonato complexes both on strong and weak sites. EXAFS spectra of selected Am samples and TRLFS spectra of selected Cm samples corroborate the model assumptions by showing the existence of different surface complexation sites and evidencing the formation of Ln/An(III) carbonate surface complexes. In the absence of carbonate and at low loadings, Ln/An(III) form strong inner-sphere complexes through binding to three Al(O,OH)6 octahedra, most likely by occupying vacant sites in the octahedral layers of montmorillonite, which are exposed on {010} and {110} edge faces. At higher loadings, Ln/An(III) binds to only one Al octahedron, forming a weaker, edge-sharing surface complex. In the presence of carbonate, we identified a ternary mono- or dicarbonato Ln/An(III) complex binding directly to one Al(O,OH)6 octahedron, revealing that type-A ternary complexes form with the one
Macroscopic Magnetic Frustration
NASA Astrophysics Data System (ADS)
Mellado, Paula; Concha, Andres; Mahadevan, L.
2012-12-01
Although geometrical frustration transcends scale, it has primarily been evoked in the micro- and mesoscopic realm to characterize such phases as spin ice, liquids, and glasses and to explain the behavior of such materials as multiferroics, high-temperature superconductors, colloids, and copolymers. Here we introduce a system of macroscopic ferromagnetic rotors arranged in a planar lattice capable of out-of-plane movement that exhibit the characteristic honeycomb spin ice rules studied and seen so far only in its mesoscopic manifestation. We find that a polarized initial state of this system settles into the honeycomb spin ice phase with relaxation on multiple time scales. We explain this relaxation process using a minimal classical mechanical model that includes Coulombic interactions between magnetic charges located at the ends of the magnets and viscous dissipation at the hinges. Our study shows how macroscopic frustration arises in a purely classical setting that is amenable to experiment, easy manipulation, theory, and computation, and shows phenomena that are not visible in their microscopic counterparts.
Nuclear physics: Macroscopic aspects
Swiatecki, W.J.
1993-12-01
A systematic macroscopic, leptodermous approach to nuclear statics and dynamics is described, based formally on the assumptions {h_bar} {yields} 0 and b/R << 1, where b is the surface diffuseness and R the nuclear radius. The resulting static model of shell-corrected nuclear binding energies and deformabilities is accurate to better than 1 part in a thousand and yields a firm determination of the principal properties of the nuclear fluid. As regards dynamics, the above approach suggests that nuclear shape evolutions will often be dominated by dissipation, but quantitative comparisons with experimental data are more difficult than in the case of statics. In its simplest liquid drop version the model exhibits interesting formal connections to the classic astronomical problem of rotating gravitating masses.
Local Realism of Macroscopic Correlations
NASA Astrophysics Data System (ADS)
Ramanathan, R.; Paterek, T.; Kay, A.; Kurzyński, P.; Kaszlikowski, D.
2011-08-01
We identify conditions under which correlations resulting from quantum measurements performed on macroscopic systems (systems composed of a number of particles of the order of the Avogadro number) can be described by local realism. We argue that the emergence of local realism at the macroscopic level is caused by an interplay between the monogamous nature of quantum correlations and the fact that macroscopic measurements do not reveal properties of individual particles.
NASA Technical Reports Server (NTRS)
Assaad, Mahmoud; Arnold, Steven M.
1999-01-01
A special class of composite laminates composed of soft rubbery matrices and stiff reinforcements made of steel wires or synthetic fibers is examined, where each constituent behaves in a nonlinear fashion even in the small strain domain. Composite laminates made of piles stacked at alternating small orientation angles with respect to the applied axial strain are primarily dominated by the nonlinear behavior of the reinforcing fibers. However; composites with large ply orientations or those perpendicular to the loading axis, will approximate the behavior of the matrix phase and respond in even a more complex fashion for arbitrarily stacked piles. The geometric nonlinearity due to small cord rotations during loading was deemed here to have a second order effect and consequently dropped from any consideration. The user subroutine USRMAT within the Micromechanics Analysis Code with the Generalized Method of Cells (MAC/GMC), was utilized to introduce the constituent material nonlinear behavior. Stress-strain behavior at the macro level was experimentally generated for single and multi ply composites comprised of continuous Nylon-66 reinforcements embedded in a carbon black loaded rubbery matrix. Comparisons between the predicted macro composite behavior and experimental results are excellent when material nonlinearity is included in the analysis. In this paper, a brief review of GMC is provided, along with a description of the nonlinear behavior of the constituents and associated constituent constitutive relations, and the improved macro (or composite) behavior predictions are documented and illustrated.
Analysis of Geological Structures
NASA Astrophysics Data System (ADS)
Price, Neville J.; Cosgrove, John W.
1990-08-01
A knowledge of structural geology is fundamental to understanding the processes by which the earth's crust has evolved. It is a subject of fundamental importance to students of geology, experienced field geologists and academic researchers as well as to petroleum and mining engineers. In contrast to many structural textbooks which dwell upon geometrical descriptions of geological structures, this book emphasises mechanical principles and the way in which they can be used to understand how and why a wide range of geological structures develop. Structures on all scales are considered but the emphasis of the book is on those that can be seen on the scale of hand specimen or outcrop. Drawing on their considerable teaching experience the authors present a coherent and lucid analysis of geological structures which will be welcomed by a wide variety of earth scientists.
Probabilistic Structural Analysis Program
NASA Technical Reports Server (NTRS)
Pai, Shantaram S.; Chamis, Christos C.; Murthy, Pappu L. N.; Stefko, George L.; Riha, David S.; Thacker, Ben H.; Nagpal, Vinod K.; Mital, Subodh K.
2010-01-01
NASA/NESSUS 6.2c is a general-purpose, probabilistic analysis program that computes probability of failure and probabilistic sensitivity measures of engineered systems. Because NASA/NESSUS uses highly computationally efficient and accurate analysis techniques, probabilistic solutions can be obtained even for extremely large and complex models. Once the probabilistic response is quantified, the results can be used to support risk-informed decisions regarding reliability for safety-critical and one-of-a-kind systems, as well as for maintaining a level of quality while reducing manufacturing costs for larger-quantity products. NASA/NESSUS has been successfully applied to a diverse range of problems in aerospace, gas turbine engines, biomechanics, pipelines, defense, weaponry, and infrastructure. This program combines state-of-the-art probabilistic algorithms with general-purpose structural analysis and lifting methods to compute the probabilistic response and reliability of engineered structures. Uncertainties in load, material properties, geometry, boundary conditions, and initial conditions can be simulated. The structural analysis methods include non-linear finite-element methods, heat-transfer analysis, polymer/ceramic matrix composite analysis, monolithic (conventional metallic) materials life-prediction methodologies, boundary element methods, and user-written subroutines. Several probabilistic algorithms are available such as the advanced mean value method and the adaptive importance sampling method. NASA/NESSUS 6.2c is structured in a modular format with 15 elements.
Buckberg, G D; Clemente, C; Cox, J L; Coghlan, H C; Castella, M; Torrent-Guasp, F; Gharib, M
2001-10-01
Torrent-Guasp's model of the helical heart is presented, which includes the cardiac muscular structures that produce 2 simple loops and that start at the pulmonary artery and end in the aorta. These components include a horizontal basal loop that surrounds the right and left ventricles, changes direction through a spiral fold in the ventricular band to cause a ventricular helix produced by now obliquely oriented fibers, forming a descending and ascending segment of the apical loop with an apical vortex. These anatomic concepts are successively activated to produce a sequence of narrowing by the basal loop, shortening by the descending segment, lengthening by the ascending segment, and widening in the cardiac cycle that causes ventricular ejection to empty and suction to fill. The factors responsible for internal torsional movements for cardiac output and suction are defined, together with mechanisms responsible for electromechanical activity produced during sequential changes in contraction and relaxation properties. These interactions of mechanical structure and function are defined in relation to pressure-related cardiac events observed from aortic, left ventricular, and left atrial recordings. PMID:11807733
[Structural sensitivity analysis].
Carrera-Hueso, F J; Ramón-Barrios, A
2011-05-01
The aim of this study was to perform a structural sensitivity analysis of a decision model and to identify its advantages and limitations. A previously published model of dinoprostone was modified, taking two scenarios into account: eliminating postpartum hemorrhages and including both hemorrhages and uterine hyperstimulation among the adverse effects. The result of the structural sensitivity analysis shows the robustness of the underlying model and confirmed the initial results: the intrauterine device is more cost-effective than intracervical dinoprostone gel. Structural sensitivity analyses should be congruent with the situation studied and clinically validated. Although uncertainty may be only slightly reduced, these analyses provide information and add greater validity and reliability to the model.
Structural analysis of glucans
Novak, Miroslav
2014-01-01
Glucans are most widespread polysaccharides in the nature. There is a large diversity in their molecular weight and configuration depending on the original source. According to the anomeric structure of glucose units it is possible to distinguish linear and branched α-, β- as well as mixed α,β-glucans with various glycoside bond positions and molecular masses. Isolation of glucans from raw sources needs removal of ballast compounds including proteins, lipids, polyphenols and other polysaccharides. Purity control of glucan fractions is necessary to evaluate the isolation and purification steps; more rigorous structural analyses of purified polysaccharides are required to clarify their structure. A set of spectroscopic, chemical and separation methods are used for this purpose. Among them, NMR spectroscopy is known as a powerful tool in structural analysis of glucans both in solution and in solid state. Along with chemolytic methods [methylation analysis (MA), periodate oxidation, partial chemical or enzymatic hydrolysis, etc.], correlation NMR experiments are able to determine the exact structure of tested polysaccharides. Vibration spectroscopic methods (FTIR, Raman) are sensitive to anomeric structure of glucans and can be used for purity control as well. Molecular weight distribution, homogeneity and branching of glucans can be estimated by size-exclusion chromatography (SEC), laser light scattering (LLS) and viscometry. PMID:25332993
COI Structural Analysis Presentation
NASA Technical Reports Server (NTRS)
Cline, Todd; Stahl, H. Philip (Technical Monitor)
2001-01-01
This report discusses the structural analysis of the Next Generation Space Telescope Mirror System Demonstrator (NMSD) developed by Composite Optics Incorporated (COI) in support of the Next Generation Space Telescope (NGST) project. The mirror was submitted to Marshall Space Flight Center (MSFC) for cryogenic testing and evaluation. Once at MSFC, the mirror was lowered to approximately 40 K and the optical surface distortions were measured. Alongside this experiment, an analytical model was developed and used to compare to the test results. A NASTRAN finite element model was provided by COI and a thermal model was developed from it. Using the thermal model, steady state nodal temperatures were calculated based on the predicted environment of the large cryogenic test chamber at MSFC. This temperature distribution was applied in the structural analysis to solve for the deflections of the optical surface. Finally, these deflections were submitted for optical analysis and comparison to the interferometer test data.
Design oriented structural analysis
NASA Technical Reports Server (NTRS)
Giles, Gary L.
1994-01-01
Desirable characteristics and benefits of design oriented analysis methods are described and illustrated by presenting a synoptic description of the development and uses of the Equivalent Laminated Plate Solution (ELAPS) computer code. ELAPS is a design oriented structural analysis method which is intended for use in the early design of aircraft wing structures. Model preparation is minimized by using a few large plate segments to model the wing box structure. Computational efficiency is achieved by using a limited number of global displacement functions that encompass all segments over the wing planform. Coupling with other codes is facilitated since the output quantities such as deflections and stresses are calculated as continuous functions over the plate segments. Various aspects of the ELAPS development are discussed including the analytical formulation, verification of results by comparison with finite element analysis results, coupling with other codes, and calculation of sensitivity derivatives. The effectiveness of ELAPS for multidisciplinary design application is illustrated by describing its use in design studies of high speed civil transport wing structures.
Macroscopic characterisations of Web accessibility
NASA Astrophysics Data System (ADS)
Lopes, Rui; Carriço, Luis
2010-12-01
The Web Science framework poses fundamental questions on the analysis of the Web, by focusing on how microscopic properties (e.g. at the level of a Web page or Web site) emerge into macroscopic properties and phenomena. One research topic on the analysis of the Web is Web accessibility evaluation, which centres on understanding how accessible a Web page is for people with disabilities. However, when framing Web accessibility evaluation on Web Science, we have found that existing research stays at the microscopic level. This article presents an experimental study on framing Web accessibility evaluation into Web Science's goals. This study resulted in novel accessibility properties of the Web not found at microscopic levels, as well as of Web accessibility evaluation processes themselves. We observed at large scale some of the empirical knowledge on how accessibility is perceived by designers and developers, such as the disparity of interpretations of accessibility evaluation tools warnings. We also found a direct relation between accessibility quality and Web page complexity. We provide a set of guidelines for designing Web pages, education on Web accessibility, as well as on the computational limits of large-scale Web accessibility evaluations.
NASA Technical Reports Server (NTRS)
Housner, J. M.; Anderson, M.; Belvin, W.; Horner, G.
1985-01-01
Dynamic analysis of large space antenna systems must treat the deployment as well as vibration and control of the deployed antenna. Candidate computer programs for deployment dynamics, and issues and needs for future program developments are reviewed. Some results for mast and hoop deployment are also presented. Modeling of complex antenna geometry with conventional finite element methods and with repetitive exact elements is considered. Analytical comparisons with experimental results for a 15 meter hoop/column antenna revealed the importance of accurate structural properties including nonlinear joints. Slackening of cables in this antenna is also a consideration. The technology of designing actively damped structures through analytical optimization is discussed and results are presented.
Continuous Feedback and Macroscopic Coherence
NASA Technical Reports Server (NTRS)
Tombesi, Paolo; Vitali, David
1996-01-01
We show that a model, recently introduced for quantum nondemolition measurements of a quantum observable, can be adapted to obtain a measurement scheme which is able to slow down the destruction of macroscopic coherence due to the measurement apparatus.
Quantal radiation from macroscopic rotation
NASA Astrophysics Data System (ADS)
Strutinsky, V.; Plujko, V.
1988-09-01
Macroscopic rotation of deformed excited nuclei may under certain conditions be accompanied by radiation of quasi-discrete gamma rays which resemble the cascade of transitions between nuclear rotational states.
NASA Technical Reports Server (NTRS)
Kobayashi, Tsunehiro
1996-01-01
Quantum macroscopic motions are investigated in the scheme consisting of N-number of harmonic oscillators in terms of ultra-power representations of nonstandard analysis. Decoherence is derived from the large internal degrees of freedom of macroscopic matters.
Macroscopic constraints on string unification
Taylor, T.R.
1989-03-01
The comparison of sting theory with experiment requires a huge extrapolation from the microscopic distances, of order of the Planck length, up to the macroscopic laboratory distances. The quantum effects give rise to large corrections to the macroscopic predictions of sting unification. I discus the model-independent constraints on the gravitational sector of string theory due to the inevitable existence of universal Fradkin-Tseytlin dilatons. 9 refs.
Computational engine structural analysis
NASA Technical Reports Server (NTRS)
Chamis, C. C.; Johns, R. H.
1986-01-01
A significant research activity at the NASA Lewis Research Center is the computational simulation of complex multidisciplinary engine structural problems. This simulation is performed using computational engine structural analysis (CESA) which consists of integrated multidisciplinary computer codes in conjunction with computer post-processing for problem-specific application. A variety of the computational simulations of specific cases are described in some detail in this paper. These case studies include: (1) aeroelastic behavior of bladed rotors, (2) high velocity impact of fan blades, (3) blade-loss transient response, (4) rotor/stator/squeeze-film/bearing interaction, (5) blade-fragment/rotor-burst containment, and (6) structural behavior of advanced swept turboprops. These representative case studies are selected to demonstrate the breath of the problems analyzed and the role of the computer including post-processing and graphical display of voluminous output data.
Predicting metapopulation lifetime from macroscopic network properties.
Drechsler, Martin
2009-03-01
This paper presents a comparatively simple approximation formula for the mean life time of a metapopulation in a habitat network where habitat patch arrangement may be irregular and patch sizes differ. It is based on previous work on the development of an analytical approximation formula by Frank and Wissel [K. Frank, C. Wissel, A formula for the mean lifetime of metapopulations in heterogeneous landscapes, Am. Nat. 159 (2002) 530] and extends it by abstracting from individual patch locations. The mean metapopulation lifetime is expressed as a function of four macroscopic network properties: the ratio of dispersal range and network size, the ratio of range of environmental correlation and network size, and the total number and (geometric mean) size of the patches. The analysis takes into account that (ceteris paribus) patches close to the boundary of the habitat network contribute less to metapopulation survival than patches close to the centre of the network. Ignoring this fact can lead to a substantial overestimation of the mean metapopulation lifetime. Due to its numerical simplicity, the formula can be used as a conservation objective function even in complex network design problems where the number of patches to be allocated is very large. Numerical tests of the formula show that it performs very well within a wide range of network structures. PMID:19159631
Structured Data in Structural Analysis Software
NASA Technical Reports Server (NTRS)
Kunz, Donald L.; Hopkins, Stewart
1987-01-01
This paper discusses the use of computer data structures in finite-element structural analysis programs. A number of data structure types that have been shown to be useful in such programs are introduced and described. A simple finite-element model is used to demonstrate how the given set of data structure types naturally lend themselves to developing software for the model. Different methods of implementing data structures in the context of a program are discussed.
Structural Analysis Made 'NESSUSary'
NASA Technical Reports Server (NTRS)
2005-01-01
Everywhere you look, chances are something that was designed and tested by a computer will be in plain view. Computers are now utilized to design and test just about everything imaginable, from automobiles and airplanes to bridges and boats, and elevators and escalators to streets and skyscrapers. Computer-design engineering first emerged in the 1970s, in the automobile and aerospace industries. Since computers were in their infancy, however, architects and engineers during the time were limited to producing only designs similar to hand-drafted drawings. (At the end of 1970s, a typical computer-aided design system was a 16-bit minicomputer with a price tag of $125,000.) Eventually, computers became more affordable and related software became more sophisticated, offering designers the "bells and whistles" to go beyond the limits of basic drafting and rendering, and venture into more skillful applications. One of the major advancements was the ability to test the objects being designed for the probability of failure. This advancement was especially important for the aerospace industry, where complicated and expensive structures are designed. The ability to perform reliability and risk assessment without using extensive hardware testing is critical to design and certification. In 1984, NASA initiated the Probabilistic Structural Analysis Methods (PSAM) project at Glenn Research Center to develop analysis methods and computer programs for the probabilistic structural analysis of select engine components for current Space Shuttle and future space propulsion systems. NASA envisioned that these methods and computational tools would play a critical role in establishing increased system performance and durability, and assist in structural system qualification and certification. Not only was the PSAM project beneficial to aerospace, it paved the way for a commercial risk- probability tool that is evaluating risks in diverse, down- to-Earth application
Sandell, Linda J.; Zhang, Bo; Wright, Rick W.; Brophy, Robert H.
2016-01-01
Objectives (i) To provide baseline knowledge of gene expression in macroscopically normal articular cartilage, (ii) to test the hypothesis that age, body-mass-index (BMI), and sex are associated with cartilage RNA transcriptome, and (iii) to predict individuals at potential risk for developing “pre-osteoarthritis” (OA) based on screening of genetic risk-alleles associated with OA and gene transcripts differentially expressed between normal and OA cartilage. Design Healthy-appearing cartilage was obtained from the medial femoral notch of 12 knees with a meniscus tear undergoing arthroscopic partial meniscectomy. Cartilage had no radiographic, magnetic-resonance-imaging or arthroscopic evidence for degeneration. RNA was subjected to Affymetrix microarrays followed by validation of selected transcripts by microfluidic digital polymerase-chain-reaction. The underlying biological processes were explored computationally. Transcriptome-wide gene expression was probed for association with known OA genetic risk-alleles assembled from published literature and for comparison with gene transcripts differentially expressed between healthy and OA cartilage from other studies. Results We generated a list of 27,641 gene transcripts in healthy cartilage. Several gene transcripts representing numerous biological processes were correlated with age and BMI and differentially expressed by sex. Based on disease-specific Ingenuity Pathways Analysis, gene transcripts associated with aging were enriched for bone/cartilage disease while the gene expression profile associated with BMI was enriched for growth-plate calcification and OA. When segregated by genetic risk-alleles, two clusters of study patients emerged, one cluster containing transcripts predicted by risk studies. When segregated by OA-associated gene transcripts, three clusters of study patients emerged, one of which is remarkably similar to gene expression pattern in OA. Conclusions Our study provides a list of gene
Active Polar Two-Fluid Macroscopic Dynamics
NASA Astrophysics Data System (ADS)
Pleiner, Harald; Svensek, Daniel; Brand, Helmut R.
2014-03-01
We study the dynamics of systems with a polar dynamic preferred direction. Examples include the pattern-forming growth of bacteria (in a solvent, shoals of fish (moving in water currents), flocks of birds and migrating insects (flying in windy air). Because the preferred direction only exists dynamically, but not statically, the macroscopic variable of choice is the macroscopic velocity associated with the motion of the active units. We derive the macroscopic equations for such a system and discuss novel static, reversible and irreversible cross-couplings connected to this second velocity. We find a normal mode structure quite different compared to the static descriptions, as well as linear couplings between (active) flow and e.g. densities and concentrations due to the genuine two-fluid transport derivatives. On the other hand, we get, quite similar to the static case, a direct linear relation between the stress tensor and the structure tensor. This prominent ``active'' term is responsible for many active effects, meaning that our approach can describe those effects as well. In addition, we also deal with explicitly chiral systems, which are important for many active systems. In particular, we find an active flow-induced heat current specific for the dynamic chiral polar order.
Macroscopic-microscopic mass models
Nix, J.R.; Moller, P.
1995-07-01
We discuss recent developments in macroscopic-microscopic mass models, including the 1992 finite-range droplet model, the 1992 extended- Thomas-Fermi Strutinsky-integral model, and the 1994 Thomas-Fermi model, with particular emphasis on how well they extrapolate to new regions of nuclei. We also address what recent developments in macroscopic-microscopic mass models are teaching us about such physically relevant issues as the nuclear curvature energy, a new congruence energy arising from a greater-than-average overlap of neutron and proton wave functions, the nuclear incompressibility coefficient, and the coulomb redistribution energy arising from a central density depression. We conclude with a brief discussion of the recently discovered rock of metastable superheavy nuclei near {sup 272}110 that had been correctly predicted by macroscopic-microscopic models, along with a possible new tack for reaching an island near {sup 290}110 beyond our present horizon.
Are cloned quantum states macroscopic?
Fröwis, F; Dür, W
2012-10-26
We study quantum states produced by optimal phase covariant quantum cloners. We argue that cloned quantum superpositions are not macroscopic superpositions in the spirit of Schrödinger's cat, despite their large particle number. This is indicated by calculating several measures for macroscopic superpositions from the literature, as well as by investigating the distinguishability of the two superposed cloned states. The latter rapidly diminishes when considering imperfect detectors or noisy states and does not increase with the system size. In contrast, we find that cloned quantum states themselves are macroscopic, in the sense of both proposed measures and their usefulness in quantum metrology with an optimal scaling in system size. We investigate the applicability of cloned states for parameter estimation in the presence of different kinds of noise.
Structural Analysis of Biodiversity
Sirovich, Lawrence; Stoeckle, Mark Y.; Zhang, Yu
2010-01-01
Large, recently-available genomic databases cover a wide range of life forms, suggesting opportunity for insights into genetic structure of biodiversity. In this study we refine our recently-described technique using indicator vectors to analyze and visualize nucleotide sequences. The indicator vector approach generates correlation matrices, dubbed Klee diagrams, which represent a novel way of assembling and viewing large genomic datasets. To explore its potential utility, here we apply the improved algorithm to a collection of almost 17000 DNA barcode sequences covering 12 widely-separated animal taxa, demonstrating that indicator vectors for classification gave correct assignment in all 11000 test cases. Indicator vector analysis revealed discontinuities corresponding to species- and higher-level taxonomic divisions, suggesting an efficient approach to classification of organisms from poorly-studied groups. As compared to standard distance metrics, indicator vectors preserve diagnostic character probabilities, enable automated classification of test sequences, and generate high-information density single-page displays. These results support application of indicator vectors for comparative analysis of large nucleotide data sets and raise prospect of gaining insight into broad-scale patterns in the genetic structure of biodiversity. PMID:20195371
Macroscopic aspects of the Unruh effect
NASA Astrophysics Data System (ADS)
Buchholz, Detlev; Verch, Rainer
2015-12-01
Macroscopic concepts pertaining to the Unruh effect are elaborated and used to clarify its physical manifestations. Based on a description of the motion of accelerated, spatially extended laboratories in Minkowski space in terms of Poincaré transformations, it is shown that, from a macroscopic perspective, an accelerated observer will not register with his measuring instruments any global thermal effects of acceleration in the inertial (Minkowskian) vacuum state. As is explained, this result is not in conflict with the well-known fact that microscopic probes used as thermometers respond non-trivially to acceleration if coupled to the vacuum. But this response cannot be interpreted as the effect of some exchange of thermal energy with a gas surrounding the observer; in fact, it is induced by the measuring process itself. It is also shown that genuine equilibrium states in a uniformly accelerated laboratory cannot be spatially homogeneous. In particular, these states coincide with the homogeneous inertial vacuum at sufficiently large distances from the horizon of the observer and consequently have the same (zero) temperature there. The analysis is carried out in the theory of a free massless scalar field; however the conclusion that the Unruh effect is not of a macroscopic thermal origin is generally valid.
Macroscopic resonances in planar geometry
NASA Astrophysics Data System (ADS)
Strutinsky, V.; Vydrug-Vlasenko, S.; Magner, A.
1987-09-01
Resonating response is a characteristic feature of free-particle system contained between two vibrating planar surfaces. Resonance frequencies and widths are determined by a mean period of motion of particles reflected from the walls. Resonances due to quasiperiodic macroscopic motion appear when the interaction among quasi-particles by means of perturbations of the common self-consistent field is included. They have finite widths corresponding to collisionless Landau dissipation. Possible relationship of this phenomenon to nuclear giant resonances is discussed.
Macroscopic nanowire networks from hierarchically assembled mesostructures
NASA Astrophysics Data System (ADS)
Wang, Donghai
Nanoscale building blocks, such as nanocrystals and one-dimensional (1D) nanostructures, have attracted tremendous attention due to their peculiar and fascinating properties. It is necessary to assemble the low dimensional nanoscale building blocks into macroscopic nanostructured architectures for potential applications in energy storage, separation, catalysis, computation, sensing, etc. This dissertation demonstrates synthesis, characterization and applications of macroscopic hierarchical metal or semiconductor (e.g., Pt, CdSe) nanowire networks. These nanowire networks were synthesized by electrodeposition within the pores of highly-ordered mesoporous silica template followed by removal of the silica template, resulting in robust nanowire networks with replicated mesopore structure. The nanowire diameter (3-10 nm) and network mesostructures (e.g. 2D, 3D and superstructures) are controlled by the pore size and the mesostructure of the silica template. As-synthesized metal nanowires self support to form networks with high electrochemical active surface area, which are further applied in enzymatic glucose sensing. Semiconductor CdSe nanowire networks show tunable optical properties dependent on nanowire diameter and have been demonstrated as a good electron acceptor in CdSe nanowire network/polymer photovoltaic devices. The dissertation also describes self-assembly behavior of composite mesostructures under physical confined environment. Novel mesostructures and mesostructured nanowire superstructures have been achieved by the confined assembly and the replication procedure mentioned above. Our approach provides an easy and efficient way to synthesize macroscopic hierarchical nanowire networks with well-controlled diameter and mesoscale arrangement, which will be of great interest for sensor, photovoltaic, and other applications.
NASA Astrophysics Data System (ADS)
Haberland, C. A.; Sonnemann, T.; Landgraf, A.; Ryberg, T.; Kulikova, G.; Krueger, F.; Dzhumabaeva, A.; Abdrakhmatov, K.; Abdybachaev, U.; Orunbaev, S.; Rosenwinkel, S.; Sharshebaev, A.
2014-12-01
Earthquakes in low-strain regions and their driving forces are still sparsely studied and understood, and constitute serious first-order research questions. Data acquisition concerning paleo-earthquakes, related hazards, and tectonic activity beyond historical records plays an important role. Such information can be obtained with tools from tectonic geomorphology, geophysics, historic seismicity, and paleo-seismology that should span a variety of time and length scales. The Chon-Kemin Valley in the northern Tien Shan (Kyrgyzstan) is a small, intermontane basin of unknown origin framed by a network of active faults. In the year 1911, the Chon-Kemin earthquake (Mw=8.1) activated fault structures of about 200 km length which also ruptured the surface along the Chon-Kemin Valley and caused numerous landslides and rock avalanches of up to several tens of millions of cubic meters in volume. The Chon-Kemin earthquake was one of a series of strong seismic events that affected the northern Tien Shan between 1885 and 1938. A seismic survey across the Chon-Kemin Valley was conducted to investigate the subsurface velocity structure of the valley and its surrounding faults. Tomographic inversion techniques were applied to first-arrival traveltimes of refracted P waves, and the seismic data were screened for reflection signatures. Additionally, the region was analyzed through paleo-seismological trenching. Tomographic and reflection images identified a shallow basin structure bounded by a set of thrust faults in the south only which - in part - correlate with the surface trace of the rupture. The deformation seems to be distributed in time and space across several sub-parallel fault strands. Synthesis of historical (analog) recordings of this earthquake provide new insights into the source mechanisms and processes.
ERIC Educational Resources Information Center
Casanova, Manuel F.; El-Baz, Ayman; Mott, Meghan; Mannheim, Glenn; Hassan, Hossam; Fahmi, Rachid; Giedd, Jay; Rumsey, Judith M.; Switala, Andrew E.; Farag, Aly
2009-01-01
Minicolumnar changes that generalize throughout a significant portion of the cortex have macroscopic structural correlates that may be visualized with modern structural neuroimaging techniques. In magnetic resonance images (MRIs) of fourteen autistic patients and 28 controls, the present study found macroscopic morphological correlates to recent…
NASA Astrophysics Data System (ADS)
Pokrovsky, O. S.; Pokrovski, G. S.; Schott, J.; Galy, A.
2006-07-01
Adsorption of germanium on goethite was studied at 25 °C in batch reactors as a function of pH (1-12), germanium concentration in solution (10 -7 to 0.002 M) and solid/solution ratio (1.8-17 g/L). The maximal surface site density determined via Ge adsorption experiments at pH from 6 to 10 is equal to 2.5 ± 0.1 μmol/m 2. The percentage of adsorbed Ge increases with pH at pH < 9, reaches a maximum at pH ˜ 9 and slightly decreases when pH is further increased to 11. These results allowed generation of a 2-p K Surface Complexation Model (SCM) which implies a constant capacitance of the electric double layer and postulates the presence of two Ge complexes, >FeO-Ge(OH)30 and >FeO-GeO(OH)2-, at the goethite-solution interface. Coprecipitation of Ge with iron oxy(hydr)oxides formed during Fe(II) oxidation by atmospheric oxygen or by Fe(III) hydrolysis in neutral solutions led to high Ge incorporations in solid with maximal Ge/Fe molar ratio close to 0.5. The molar Ge/Fe ratio in precipitated solid is proportional to that in the initial solution according to the equation (Ge/Fe) solid = k × (Ge/Fe) solution with 0.7 ⩽ k ⩽ 1.0. The structure of adsorbed and coprecipitated Ge complexes was further characterized using XAFS spectroscopy. In agreement with previous data on oxyanions adsorption on goethite, bi-dentate bi-nuclear surface complexes composed of tetrahedrally coordinated Ge attached to the corners of two adjacent Fe octahedra represent the dominant contribution to the EXAFS signal. Coprecipitated samples with Ge/Fe molar ratios >0.1, and samples not aged in solution (<1 day) having intermediate Ge/Fe ratios (0.01-0.1) show 4 ± 0.3 oxygen atoms at 1.76 ± 0.01 Å around Ge. Samples less concentrated in Ge (0.001 < Ge/Fe < 0.10) and aged longer times in solution (up to 280 days) exhibit a splitting of the first atomic shell with Ge in both tetrahedral ( R = 1.77 ± 0.02 Å) and octahedral ( R = 1.92 ± 0.03 Å) coordination with oxygen. In these samples
Making Macroscopic Assemblies of Aligned Carbon Nanotubes
NASA Technical Reports Server (NTRS)
Smalley, Richard E.; Colbert, Daniel T.; Smith, Ken A.; Walters, Deron A.; Casavant, Michael J.; Qin, Xiaochuan; Yakobson, Boris; Hauge, Robert H.; Saini, Rajesh Kumar; Chiung, Wan-Ting; Huffman, Charles B.
2005-01-01
A method of aligning and assembling single-wall carbon nanotubes (SWNTs) to fabricate macroscopic structures has been invented. The method entails suspending SWNTs in a fluid, orienting the SWNTs by use of a magnetic and/or electric field, and then removing the aligned SWNTs from suspension in such a way as to assemble them while maintaining the alignment. SWNTs are essentially tubular extensions of fullerene molecules. It is desirable to assemble aligned SWNTs into macroscopic structures because the common alignment of the SWNTs in such a structure makes it possible to exploit, on a macroscopic scale, the unique mechanical, chemical, and electrical properties that individual oriented SWNTs exhibit at the molecular level. Because of their small size and high electrical conductivity, carbon nanotubes, and especially SWNTs, are useful for making electrical connectors in integrated circuits. Carbon nanotubes can be used as antennas at optical frequencies, and as probes in scanning tunneling microscopes, atomic-force microscopes, and the like. Carbon nanotubes can be used with or instead of carbon black in tires. Carbon nanotubes are useful as supports for catalysts. Ropes of SWNTs are metallic and, as such, are potentially useful in some applications in which electrical conductors are needed - for example, they could be used as additives in formulating electrically conductive paints. Finally, macroscopic assemblies of aligned SWNTs can serve as templates for the growth of more and larger structures of the same type. The great variety of tubular fullerene molecules and of the structures that could be formed by assembling them in various ways precludes a complete description of the present method within the limits of this article. It must suffice to present a typical example of the use of one of many possible variants of the method to form a membrane comprising SWNTs aligned substantially parallel to each other in the membrane plane. The apparatus used in this variant
Regularized Generalized Structured Component Analysis
ERIC Educational Resources Information Center
Hwang, Heungsun
2009-01-01
Generalized structured component analysis (GSCA) has been proposed as a component-based approach to structural equation modeling. In practice, GSCA may suffer from multi-collinearity, i.e., high correlations among exogenous variables. GSCA has yet no remedy for this problem. Thus, a regularized extension of GSCA is proposed that integrates a ridge…
Microscopic versus macroscopic calculation of dielectric nanospheres
NASA Astrophysics Data System (ADS)
Kühn, M.; Kliem, H.
2008-12-01
The issue of nanodielectrics has recently become an important field of interest. The term describes nanometric dielectrics, i. e. dielectric materials with structural dimensions typically smaller than 100 run. In contrast to the behaviour of a bulk material the nanodielectrics can behave completely different. With shrinking dimensions the surface or rather boundary effects outweigh the volume effects. This leads to a different observable physics at the nanoscale. A crucial point is the question whether a continuum model for the calculation of dielectric properties is still applicable for these nanomaterials. In order to answer this question we simulated dielectric nanospheres with a microscopic local field method and compared the results to the macroscopic mean field theory.
Fibrous random materials: From microstructure to macroscopic properties
NASA Astrophysics Data System (ADS)
Yazdchi, K.; Luding, S.
2013-06-01
Fibrous porous materials are involved in a wide range of applications including composite materials, fuel cells, heat exchangers and (biological)filters. Fluid flow through these materials plays an important role in many engineering applications and processes, such as textiles and paper manufacturing or transport of (under)ground water and pollutants. While most porous materials have complex geometry, some can be seen as two-dimensional particulate/fibrous systems, in which we introduce several microscopic quantities, based on Voronoi and Delaunay tessellations, to characterize their microstructure. In particular, by analyzing the topological properties of Voronoi polygons, we observe a smooth transition from disorder to order, for increasing packing fraction. Using fully resolved finite element (FE) simulations of Newtonian, incompressible fluid flow perpendicular to the fibres, the macroscopic permeability is calculated in creeping flow regimes. The effect of fibre arrangement and local crystalline regions on the macroscopic permeability is discussed and the macroscopic property is linked to the microscopic structural quantities.
The Advantages of Not Entangling Macroscopic Diamonds at Room Temperature
Brezinski, Mark E.
2013-01-01
The recent paper entitled by K. C. Lee et al. (2011) establishes nonlocal macroscopic quantum correlations, which they term “entanglement”, under ambient conditions. Photon(s)-phonon entanglements are established within each interferometer arm. However, our analysis demonstrates, the phonon fields between arms become correlated as a result of single-photon wavepacket path indistinguishability, not true nonlocal entanglement. We also note that a coherence expansion (as opposed to decoherence) resulted from local entanglement which was not recognized. It occurred from nearly identical Raman scattering in each arm (importantly not meeting the Born and Markovian approximations). The ability to establish nonlocal macroscopic quantum correlations through path indistinguishability rather than entanglement offers the opportunity to greatly expand quantum macroscopic theory and application, even though it was not true nonlocal entanglement. PMID:27429619
Sagnac interferometry as a probe to the commutation relation of a macroscopic quantum mirror
Yang Ran; Gong Xuefei; Pei Shouyong; Luo Ziren; Lau, Y. K.
2010-09-15
Single photon Sagnac interferometry as a probe to macroscopic quantum mechanics is considered at the theoretical level. For a freely moving macroscopic quantum mirror susceptible to radiation pressure force inside a Sagnac interferometer, a careful analysis of the input-output relation reveals that the particle spectrum readout at the bright and dark ports encode information concerning the noncommutativity of position and momentum of the macroscopic mirror. A feasible experimental scheme to probe the commutation relation of a macroscopic quantum mirror is outlined to explore the possible frontier between classical and quantum regimes. In the Appendix, the case of Michelson interferometry as a feasible probe is also sketched.
CODSTRAN: Composite durability structural analysis
NASA Technical Reports Server (NTRS)
Chamis, C. C.; Smith, G. T.
1978-01-01
CODSTRAN (COmposite Durability STRuctural ANalysis) is an integrated computer program being developed for the prediction of defect growth and fracture of composite structures subjected to service loads and environments. CODSTRAN is briefly described with respect to organization, capabilities and present status. Application of CODSTRAN current capability to a flat composite laminate with a center slit which was subjected to axial tension loading predicted defect growth which is in good agreement with C-scan ultrasonic test records.
NASA Astrophysics Data System (ADS)
Das, Sambit; Iyer, Mrinal; Radhakrishnan, Balachandran; Gavini, Vikram
2016-10-01
The studies reported in Section 3.1 on core size and core energetics were all conducted using finite-element meshes which had discretization errors of under 0.005 eV in the computed dislocation energies (Ed, refer to Eq. (8)). However, we have accidentally used a slightly coarser mesh for the study reported in Section 3.2 on the dependence of the dislocation core energy on macroscopic deformations. This issue came to light recently while conducting a follow-up study on interacting dislocations. Thus, we proceeded to repeat our study reported in Section 3.2 of the article with finite-element meshes that result in discretization errors under 0.005 eV. While the qualitative results reported in Section 3.2 of the manuscript change remain unchanged-i.e. there is a considerable dependence of the dislocation core-energy on macroscopic deformations, and the slopes corresponding to the core-energy dependence on macroscopic strains are non-zero at zero macroscopic strain-there are considerable quantitative changes. The new results are provided in Figs. 1-4 for the various macroscopic strains considered.
Structural analysis of aligned RNAs.
Voss, Björn
2006-01-01
The knowledge about classes of non-coding RNAs (ncRNAs) is growing very fast and it is mainly the structure which is the common characteristic property shared by members of the same class. For correct characterization of such classes it is therefore of great importance to analyse the structural features in great detail. In this manuscript I present RNAlishapes which combines various secondary structure analysis methods, such as suboptimal folding and shape abstraction, with a comparative approach known as RNA alignment folding. RNAlishapes makes use of an extended thermodynamic model and covariance scoring, which allows to reward covariation of paired bases. Applying the algorithm to a set of bacterial trp-operon leaders using shape abstraction it was able to identify the two alternating conformations of this attenuator. Besides providing in-depth analysis methods for aligned RNAs, the tool also shows a fairly well prediction accuracy. Therefore, RNAlishapes provides the community with a powerful tool for structural analysis of classes of RNAs and is also a reasonable method for consensus structure prediction based on sequence alignments. RNAlishapes is available for online use and download at http://rna.cyanolab.de. PMID:17020924
Structural Analysis of Communication Development.
ERIC Educational Resources Information Center
Conville, Richard L.
This paper discusses the question of the legitimacy of applying structural analysis to actual human behavior and illustrates its legitimacy by using the reasoning in an essay by Paul Ricoeur. It then asks if the principles of communication development (obliqueness, exchange, and dying) derived from Helen Keller's experience of communication…
Structural Analysis and Design Software
NASA Technical Reports Server (NTRS)
1997-01-01
Collier Research and Development Corporation received a one-of-a-kind computer code for designing exotic hypersonic aircraft called ST-SIZE in the first ever Langley Research Center software copyright license agreement. Collier transformed the NASA computer code into a commercial software package called HyperSizer, which integrates with other Finite Element Modeling and Finite Analysis private-sector structural analysis program. ST-SIZE was chiefly conceived as a means to improve and speed the structural design of a future aerospace plane for Langley Hypersonic Vehicles Office. Including the NASA computer code into HyperSizer has enabled the company to also apply the software to applications other than aerospace, including improved design and construction for offices, marine structures, cargo containers, commercial and military aircraft, rail cars, and a host of everyday consumer products.
Efficient Analysis of Complex Structures
NASA Technical Reports Server (NTRS)
Kapania, Rakesh K.
2000-01-01
Last various accomplishments achieved during this project are : (1) A Survey of Neural Network (NN) applications using MATLAB NN Toolbox on structural engineering especially on equivalent continuum models (Appendix A). (2) Application of NN and GAs to simulate and synthesize substructures: 1-D and 2-D beam problems (Appendix B). (3) Development of an equivalent plate-model analysis method (EPA) for static and vibration analysis of general trapezoidal built-up wing structures composed of skins, spars and ribs. Calculation of all sorts of test cases and comparison with measurements or FEA results. (Appendix C). (4) Basic work on using second order sensitivities on simulating wing modal response, discussion of sensitivity evaluation approaches, and some results (Appendix D). (5) Establishing a general methodology of simulating the modal responses by direct application of NN and by sensitivity techniques, in a design space composed of a number of design points. Comparison is made through examples using these two methods (Appendix E). (6) Establishing a general methodology of efficient analysis of complex wing structures by indirect application of NN: the NN-aided Equivalent Plate Analysis. Training of the Neural Networks for this purpose in several cases of design spaces, which can be applicable for actual design of complex wings (Appendix F).
Structural analysis of vibroacoustical processes
NASA Technical Reports Server (NTRS)
Gromov, A. P.; Myasnikov, L. L.; Myasnikova, Y. N.; Finagin, B. A.
1973-01-01
The method of automatic identification of acoustical signals, by means of the segmentation was used to investigate noises and vibrations in machines and mechanisms, for cybernetic diagnostics. The structural analysis consists of presentation of a noise or vibroacoustical signal as a sequence of segments, determined by the time quantization, in which each segment is characterized by specific spectral characteristics. The structural spectrum is plotted as a histogram of the segments, also as a relation of the probability density of appearance of a segment to the segment type. It is assumed that the conditions of ergodic processes are maintained.
Structured Functional Principal Component Analysis
Shou, Haochang; Zipunnikov, Vadim; Crainiceanu, Ciprian M.; Greven, Sonja
2015-01-01
Summary Motivated by modern observational studies, we introduce a class of functional models that expand nested and crossed designs. These models account for the natural inheritance of the correlation structures from sampling designs in studies where the fundamental unit is a function or image. Inference is based on functional quadratics and their relationship with the underlying covariance structure of the latent processes. A computationally fast and scalable estimation procedure is developed for high-dimensional data. Methods are used in applications including high-frequency accelerometer data for daily activity, pitch linguistic data for phonetic analysis, and EEG data for studying electrical brain activity during sleep. PMID:25327216
Uncertainty Analysis of Composite Structures
NASA Technical Reports Server (NTRS)
Noor, Ahmed K.; Starnes, James H., Jr.; Peters, Jeanne M.
2000-01-01
A two-phase approach and a computational procedure are presented for predicting the variability in the nonlinear response of composite structures associated with variations in the geometric and material parameters of the structure. In the first phase, hierarchical sensitivity analysis is used to identify the major parameters, which have the most effect on the response quantities of interest. In the second phase, the major parameters are taken to be fuzzy parameters, and a fuzzy set analysis is used to determine the range of variation of the response, associated with preselected variations in the major parameters. The effectiveness of the procedure is demonstrated by means of a numerical example of a cylindrical panel with four T-shaped stiffeners and a circular cutout.
Anovitz, Lawrence {Larry} M; Mamontov, Eugene; Ishai, Paul ben; Kolesnikov, Alexander I
2013-01-01
The properties of fluids can be significantly altered by the geometry of their confining environments. While there has been significant work on the properties of such confined fluids, the properties of fluids under ultraconfinement, environments where, at least in one plane, the dimensions of the confining environment are similar to that of the confined molecule, have not been investigated. This paper investigates the dynamic properties of water in beryl (Be3Al2Si6O18), the structure of which contains approximately 5-A-diam channels parallel to the c axis. Three techniques, inelastic neutron scattering, quasielastic neutron scattering, and dielectric spectroscopy, have been used to quantify these properties over a dynamic range covering approximately 16 orders of magnitude. Because beryl can be obtained in large single crystals we were able to quantify directional variations, perpendicular and parallel to the channel directions, in the dynamics of the confined fluid. These are significantly anisotropic and, somewhat counterintuitively, show that vibrations parallel to the c-axis channels are significantly more hindered than those perpendicular to the channels. The effective potential for vibrations in the c direction is harder than the potential in directions perpendicular to it. There is evidence of single-file diffusion of water molecules along the channels at higher temperatures, but below 150 K this diffusion is strongly suppressed. No such suppression, however, has been observed in the channel-perpendicular direction. Inelastic neutron scattering spectra include an intramolecular stretching O-H peak at 465 meV. As this is nearly coincident with that known for free water molecules and approximately 30 meV higher than that in liquid water or ice, this suggests that there is no hydrogen bonding constraining vibrations between the channel water and the beryl structure. However, dielectric spectroscopic measurements at higher temperatures and lower frequencies
Grid Stiffened Structure Analysis Tool
NASA Technical Reports Server (NTRS)
1999-01-01
The Grid Stiffened Analysis Tool contract is contract performed by Boeing under NASA purchase order H30249D. The contract calls for a "best effort" study comprised of two tasks: (1) Create documentation for a composite grid-stiffened structure analysis tool, in the form of a Microsoft EXCEL spread sheet, that was developed by originally at Stanford University and later further developed by the Air Force, and (2) Write a program that functions as a NASTRAN pre-processor to generate an FEM code for grid-stiffened structure. In performing this contract, Task 1 was given higher priority because it enables NASA to make efficient use of a unique tool they already have; Task 2 was proposed by Boeing because it also would be beneficial to the analysis of composite grid-stiffened structures, specifically in generating models for preliminary design studies. The contract is now complete, this package includes copies of the user's documentation for Task 1 and a CD ROM & diskette with an electronic copy of the user's documentation and an updated version of the "GRID 99" spreadsheet.
Timm, David M.; Chen, Jianbo; Sing, David; Gage, Jacob A.; Haisler, William L.; Neeley, Shane K.; Raphael, Robert M.; Dehghani, Mehdi; Rosenblatt, Kevin P.; Killian, T. C.; Tseng, Hubert; Souza, Glauco R.
2013-01-01
There is a growing demand for in vitro assays for toxicity screening in three-dimensional (3D) environments. In this study, 3D cell culture using magnetic levitation was used to create an assay in which cells were patterned into 3D rings that close over time. The rate of closure was determined from time-lapse images taken with a mobile device and related to drug concentration. Rings of human embryonic kidney cells (HEK293) and tracheal smooth muscle cells (SMCs) were tested with ibuprofen and sodium dodecyl sulfate (SDS). Ring closure correlated with the viability and migration of cells in two dimensions (2D). Images taken using a mobile device were similar in analysis to images taken with a microscope. Ring closure may serve as a promising label-free and quantitative assay for high-throughput in vivo toxicity in 3D cultures. PMID:24141454
Timm, David M; Chen, Jianbo; Sing, David; Gage, Jacob A; Haisler, William L; Neeley, Shane K; Raphael, Robert M; Dehghani, Mehdi; Rosenblatt, Kevin P; Killian, T C; Tseng, Hubert; Souza, Glauco R
2013-01-01
There is a growing demand for in vitro assays for toxicity screening in three-dimensional (3D) environments. In this study, 3D cell culture using magnetic levitation was used to create an assay in which cells were patterned into 3D rings that close over time. The rate of closure was determined from time-lapse images taken with a mobile device and related to drug concentration. Rings of human embryonic kidney cells (HEK293) and tracheal smooth muscle cells (SMCs) were tested with ibuprofen and sodium dodecyl sulfate (SDS). Ring closure correlated with the viability and migration of cells in two dimensions (2D). Images taken using a mobile device were similar in analysis to images taken with a microscope. Ring closure may serve as a promising label-free and quantitative assay for high-throughput in vivo toxicity in 3D cultures. PMID:24141454
NASA Astrophysics Data System (ADS)
Timm, David M.; Chen, Jianbo; Sing, David; Gage, Jacob A.; Haisler, William L.; Neeley, Shane K.; Raphael, Robert M.; Dehghani, Mehdi; Rosenblatt, Kevin P.; Killian, T. C.; Tseng, Hubert; Souza, Glauco R.
2013-10-01
There is a growing demand for in vitro assays for toxicity screening in three-dimensional (3D) environments. In this study, 3D cell culture using magnetic levitation was used to create an assay in which cells were patterned into 3D rings that close over time. The rate of closure was determined from time-lapse images taken with a mobile device and related to drug concentration. Rings of human embryonic kidney cells (HEK293) and tracheal smooth muscle cells (SMCs) were tested with ibuprofen and sodium dodecyl sulfate (SDS). Ring closure correlated with the viability and migration of cells in two dimensions (2D). Images taken using a mobile device were similar in analysis to images taken with a microscope. Ring closure may serve as a promising label-free and quantitative assay for high-throughput in vivo toxicity in 3D cultures.
Towards a macroscopic generator coordinate method
NASA Astrophysics Data System (ADS)
Strutinsky, V. M.; Ivanyuk, F. A.; Vydrug-Vlasenko, S. M.
1992-09-01
Collective quantities are defined as macroscopic statistical averages over many level crossing points where microscopic densities are redistributed. Accordingly, the generator coordinate method (GCM) is reconsidered. It is concluded that, contrary to earlier arguments, the macroscopically defined inertia parameter which appears in the GCM Hamiltonian has a finite value close to that obtained using traditional theories assuming the existence of the adiabatic BCS ground state.
Macroscopic ordering of helical pores for arraying guest molecules noncentrosymmetrically
Li, Chunji; Cho, Joonil; Yamada, Kuniyo; Hashizume, Daisuke; Araoka, Fumito; Takezoe, Hideo; Aida, Takuzo; Ishida, Yasuhiro
2015-01-01
Helical nanostructures have attracted continuous attention, not only as media for chiral recognition and synthesis, but also as motifs for studying intriguing physical phenomena that never occur in centrosymmetric systems. To improve the quality of signals from these phenomena, which is a key issue for their further exploration, the most straightforward is the macroscopic orientation of helices. Here as a versatile scaffold to rationally construct this hardly accessible structure, we report a polymer framework with helical pores that unidirectionally orient over a large area (∼10 cm2). The framework, prepared by crosslinking a supramolecular liquid crystal preorganized in a magnetic field, is chemically robust, functionalized with carboxyl groups and capable of incorporating various basic or cationic guest molecules. When a nonlinear optical chromophore is incorporated in the framework, the resultant complex displays a markedly efficient nonlinear optical output, owing to the coherence of signals ensured by the macroscopically oriented helical structure. PMID:26416086
Macroscopic ordering of helical pores for arraying guest molecules noncentrosymmetrically
NASA Astrophysics Data System (ADS)
Li, Chunji; Cho, Joonil; Yamada, Kuniyo; Hashizume, Daisuke; Araoka, Fumito; Takezoe, Hideo; Aida, Takuzo; Ishida, Yasuhiro
2015-09-01
Helical nanostructures have attracted continuous attention, not only as media for chiral recognition and synthesis, but also as motifs for studying intriguing physical phenomena that never occur in centrosymmetric systems. To improve the quality of signals from these phenomena, which is a key issue for their further exploration, the most straightforward is the macroscopic orientation of helices. Here as a versatile scaffold to rationally construct this hardly accessible structure, we report a polymer framework with helical pores that unidirectionally orient over a large area (~10 cm2). The framework, prepared by crosslinking a supramolecular liquid crystal preorganized in a magnetic field, is chemically robust, functionalized with carboxyl groups and capable of incorporating various basic or cationic guest molecules. When a nonlinear optical chromophore is incorporated in the framework, the resultant complex displays a markedly efficient nonlinear optical output, owing to the coherence of signals ensured by the macroscopically oriented helical structure.
NASA Astrophysics Data System (ADS)
Wu, Y.; Chen, G. L.; Hui, X. D.; Liu, C. T.; Lin, Y.; Shang, X. C.; Lu, Z. P.
2009-10-01
Based on mechanical instability of individual shear transformation zones (STZs), a quantitative link between the microplastic instability and macroscopic deformation behavior of metallic glasses was proposed. Our analysis confirms that macroscopic metallic glasses comprise a statistical distribution of STZ embryos with distributed values of activation energy, and the microplastic instability of all the individual STZs dictates the macroscopic deformation behavior of amorphous solids. The statistical model presented in this paper can successfully reproduce the macroscopic stress-strain curves determined experimentally and readily be used to predict strain-rate effects on the macroscopic responses with the availability of the material parameters at a certain strain rate, which offer new insights into understanding the actual deformation mechanism in amorphous solids.
The macroscopic delamination of thin films from elastic substrates
Vella, Dominic; Bico, José; Boudaoud, Arezki; Roman, Benoit; Reis, Pedro M.
2009-01-01
The wrinkling and delamination of stiff thin films adhered to a polymer substrate have important applications in “flexible electronics.” The resulting periodic structures, when used for circuitry, have remarkable mechanical properties because stretching or twisting of the substrate is mostly accommodated through bending of the film, which minimizes fatigue or fracture. To date, applications in this context have used substrate patterning to create an anisotropic substrate-film adhesion energy, thereby producing a controlled array of delamination “blisters.” However, even in the absence of such patterning, blisters appear spontaneously, with a characteristic size. Here, we perform well-controlled experiments at macroscopic scales to study what sets the dimensions of these blisters in terms of the material properties and explain our results by using a combination of scaling and analytical methods. Besides pointing to a method for determining the interfacial toughness, our analysis suggests a number of design guidelines for the thin films used in flexible electronic applications. Crucially, we show that, to avoid the possibility that delamination may cause fatigue damage, the thin film thickness must be greater than a critical value, which we determine. PMID:19556551
The Proell Effect: A Macroscopic Maxwell's Demon
NASA Astrophysics Data System (ADS)
Rauen, Kenneth M.
2011-12-01
Maxwell's Demon is a legitimate challenge to the Second Law of Thermodynamics when the "demon" is executed via the Proell effect. Thermal energy transfer according to the Kinetic Theory of Heat and Statistical Mechanics that takes place over distances greater than the mean free path of a gas circumvents the microscopic randomness that leads to macroscopic irreversibility. No information is required to sort the particles as no sorting occurs; the entire volume of gas undergoes the same transition. The Proell effect achieves quasi-spontaneous thermal separation without sorting by the perturbation of a heterogeneous constant volume system with displacement and regeneration. The classical analysis of the constant volume process, such as found in the Stirling Cycle, is incomplete and therefore incorrect. There are extra energy flows that classical thermo does not recognize. When a working fluid is displaced across a regenerator with a temperature gradient in a constant volume system, complimentary compression and expansion work takes place that transfers energy between the regenerator and the bulk gas volumes of the hot and cold sides of the constant volume system. Heat capacity at constant pressure applies instead of heat capacity at constant volume. The resultant increase in calculated, recyclable energy allows the Carnot Limit to be exceeded in certain cycles. Super-Carnot heat engines and heat pumps have been designed and a US patent has been awarded.
Structural Analysis of Fungal Cerebrosides
Barreto-Bergter, Eliana; Sassaki, Guilherme L.; de Souza, Lauro M.
2011-01-01
Of the ceramide monohexosides (CMHs), gluco- and galactosyl-ceramides are the main neutral glycosphingolipids expressed in fungal cells. Their structural determination is greatly dependent on the use of mass spectrometric techniques, including fast atom bombardment-mass spectrometry, electrospray ionization, and energy collision-induced dissociation mass spectrometry. Nuclear magnetic resonance has also been used successfully. Such a combination of techniques, combined with classical analytical separation, such as high-performance thin layer chromatography and column chromatography, has led to the structural elucidation of a great number of fungal CMHs. The structure of fungal CMH is conserved among fungal species and consists of a glucose or galactose residue attached to a ceramide moiety containing 9-methyl-4,8-sphingadienine with an amidic linkage to hydroxylated fatty acids, most commonly having 16 or 18 carbon atoms and unsaturation between C-3 and C-4. Along with their unique structural characteristics, fungal CMHs have a peculiar subcellular distribution and striking biological properties. Fungal cerebrosides were also characterized as antigenic molecules directly or indirectly involved in cell growth or differentiation in Schizophyllum commune, Cryptococcus neoformans, Pseudallescheria boydii, Candida albicans, Aspergillus nidulans, Aspergillus fumigatus, and Colletotrichum gloeosporioides. Besides classical techniques for cerebroside (CMH) analysis, we now describe new approaches, combining conventional thin layer chromatography and mass spectrometry, as well as emerging technologies for subcellular localization and distribution of glycosphingolipids by secondary ion mass spectrometry and imaging matrix-assisted laser desorption ionization time-of-flight. PMID:22164155
Random-phase approximation as a macroscopic description
NASA Astrophysics Data System (ADS)
Strutinsky, V. M.; Abrosimov, V. I.
1990-09-01
Analysis of nuclear processes in terms of cross-sections averaged over the many microscopic channels, as in the “poor resolution” experiments, corresponds to a macroscopic level of description. In this paper energy-averaged strength function is considered. In order to determine the frequency dependence of this quantity statistically averaged single-particle density is introduced for which equations are obtained analogous to random phase approximation.
Macroscopic Description for Networks of Spiking Neurons
NASA Astrophysics Data System (ADS)
Montbrió, Ernest; Pazó, Diego; Roxin, Alex
2015-04-01
A major goal of neuroscience, statistical physics, and nonlinear dynamics is to understand how brain function arises from the collective dynamics of networks of spiking neurons. This challenge has been chiefly addressed through large-scale numerical simulations. Alternatively, researchers have formulated mean-field theories to gain insight into macroscopic states of large neuronal networks in terms of the collective firing activity of the neurons, or the firing rate. However, these theories have not succeeded in establishing an exact correspondence between the firing rate of the network and the underlying microscopic state of the spiking neurons. This has largely constrained the range of applicability of such macroscopic descriptions, particularly when trying to describe neuronal synchronization. Here, we provide the derivation of a set of exact macroscopic equations for a network of spiking neurons. Our results reveal that the spike generation mechanism of individual neurons introduces an effective coupling between two biophysically relevant macroscopic quantities, the firing rate and the mean membrane potential, which together govern the evolution of the neuronal network. The resulting equations exactly describe all possible macroscopic dynamical states of the network, including states of synchronous spiking activity. Finally, we show that the firing-rate description is related, via a conformal map, to a low-dimensional description in terms of the Kuramoto order parameter, called Ott-Antonsen theory. We anticipate that our results will be an important tool in investigating how large networks of spiking neurons self-organize in time to process and encode information in the brain.
Macroscopic aspects of interfacial reactions
NASA Technical Reports Server (NTRS)
Heckel, R. W.
1976-01-01
The extent of interdiffusion and formation of new phases is determined by the constitution diagram of the alloy system, the interdiffusion coefficients of the phases present, and the thermal conditions (temperature and time) associated with the bonding process and/or subsequent use of the bonded structure. In many instance, the kinetics of interdiffusion and phase formation can be predicted from known parameters using numerical methods and computer techniques. Predictions are compared with experimentally determined parameters for a variety of metallurgical alloy systems.
Examining brain microstructure using structure tensor analysis of histological sections.
Budde, Matthew D; Frank, Joseph A
2012-10-15
The mammalian central nervous system has a tremendous structural complexity, and diffusion tensor imaging (DTI) is unique in its ability to extract microstructural tissue properties at a macroscopic scale. However, despite its widespread use and applications in clinical and research settings, accurate validation of DTI has notoriously lagged the advances in image acquisition and analysis. In this report, we demonstrate an approach to visualize and quantify the microscopic features of histological sections on multiple length scales using techniques derived from image texture analysis. Structure tensor (ST) analysis was applied to fluorescence microscopy images of rat brain sections to visualize and quantify tissue microstructure. Images were digitally color-coded based on the local orientation in the pixelwise ST implementation, which allowed direct visualization of white matter complexity at the microscopic level. A piecewise ST algorithm was also employed to quantify anisotropy and orientation at a resolution comparable to that typically acquired with DTI. Anisotropy measured with ST analysis of stained histological sections was highly correlated with anisotropy measured by ex vivo DTI of the same brains (R(2)=0.92). Furthermore, angular histograms, or Fiber Orientation Distributions (FODs), were computed to mimic similar measures derived from high angular resolution diffusion imaging methods. The FODs for each pixel were fit to a mixture of von Mises distributions to identify putative regions of multiple fiber populations (i.e. crossing fibers). Despite its current application to two-dimensional microscopy, the ST analysis is a novel approach to visualize and quantify microstructure in the central nervous system in both health and disease, and advances the available set of tools for validating DTI and other diffusion MRI techniques. PMID:22759994
Effect of ultraviolet light irradiation on macroscopic single-walled carbon nanotube bundles
Miko, Cs.; Milas, M.; Seo, J.W.; Gaal, R.; Kulik, A.; Forro, L.
2006-04-10
We have measured the electrical conductivity and the Young modulus of macroscopic oriented ropes containing single-walled carbon nanotubes under ultraviolet (UV) irradiation. We found that UV irradiation increases both the electrical conductivity and the strength of the macroscopic bundle. These phenomena are explained by the generation of cross-links between the tubes in the macroscopic bundle due to the UV-induced interaction between the solvent dimethyl-formamide and the free radicals present on the surface of carbon nanotubes. Transmission electron microscopy investigation shows that the wall structure of nanotubes is preserved during this process, which is a valuable advantage compared to electron irradiation.
Nanoplasmon-enabled macroscopic thermal management
Jonsson, Gustav Edman; Miljkovic, Vladimir; Dmitriev, Alexandre
2014-01-01
In numerous applications of energy harvesting via transformation of light into heat the focus recently shifted towards highly absorptive nanoplasmonic materials. It is currently established that noble metals-based absorptive plasmonic platforms deliver significant light-capturing capability and can be viewed as super-absorbers of optical radiation. Naturally, approaches to the direct experimental probing of macroscopic temperature increase resulting from these absorbers are welcomed. Here we derive a general quantitative method of characterizing heat-generating properties of optically absorptive layers via macroscopic thermal imaging. We further monitor macroscopic areas that are homogeneously heated by several degrees with nanostructures that occupy a mere 8% of the surface, leaving it essentially transparent and evidencing significant heat generation capability of nanoplasmon-enabled light capture. This has a direct bearing to a large number of applications where thermal management is crucial. PMID:24870613
Quantum communication with macroscopically bright nonclassical states.
Usenko, Vladyslav C; Ruppert, Laszlo; Filip, Radim
2015-11-30
We analyze homodyne detection of macroscopically bright multimode nonclassical states of light and propose their application in quantum communication. We observe that the homodyne detection is sensitive to a mode-matching of the bright light to the highly intense local oscillator. Unmatched bright modes of light result in additional noise which technically limits detection of Gaussian entanglement at macroscopic level. When the mode-matching is sufficient, we show that multimode quantum key distribution with bright beams is feasible. It finally merges the quantum communication with classical optical technology of visible beams of light.
Effects of Microstructure Variations on Macroscopic Terahertz Metafilm Properties
O'Hara, John F.; Smirnova, Evgenya; Azad, Abul K.; Chen, Hou-Tong; Taylor, Antoinette J.
2007-01-01
The properties of planar, single-layer metamaterials, or metafilms, are studied by varying the structural components of the split-ring resonators used to comprise the overall medium. Measurements and simulations reveal how minor design variations in split-ring resonator structures can result in significant changes in the macroscopic properties of the metafilm. A transmission-line/circuit model is also used to clarify some of the behavior and design limitations of the metafilms. Though our results are illustrated in the terahertz frequency range, the work has broader implications, particularly with respect to filtering, modulation, and switching devices.
Jeong, Hyunseok
2005-09-15
Recently, there have been several suggestions that weak Kerr nonlinearity can be used for generation of macroscopic superpositions and entanglement and for linear optics quantum computation. However, it is not immediately clear that this approach can overcome decoherence effects. Our numerical study shows that nonlinearity of weak strength could be useful for macroscopic entanglement generation and quantum gate operations in the presence of decoherence. We suggest specific values for real experiments based on our analysis. Our discussion shows that the generation of macroscopic entanglement using this approach is within the reach of current technology.
Srivastava, Vikram K; Quinlan, Ronald; Agapov, Alexander L; Dunlap, John R; Nelson, Kimberly M; Duranty, Edward R; Sokolov, Alexei P; Bhat, Gajanan; Mays, Jimmy
2014-01-01
The excellent properties exhibited by monolayer graphene have spurred the development of exfoliation techniques using bulk graphite to produce large quantities of pristine monolayer sheets. Development of simple chemistry to exfoliate and intercalate graphite and graphite mimics in large quantities is required for numerous applications. To determine the macroscopic behavior of restacked, exfoliated bulk materials, a systematic approach is presented using a simple, redox-liquid sonication process along to obtain large quantities of 2D and 3D hexagonally layered graphite, molybdenum disulfi de, and boron nitride, which are subsequently characterized to observe chemical and structural changes. For MoS 2 sonicated with the antioxidant sodium bisulfi te, results from Raman spectroscopy, X-ray diffraction, and electron microscopy indicate the presence of distorted phases from different polymorphs, and apparent nanotube structures in the bulk, restacked powder. Furthermore, using thermograviemtric analysis, the antioxidant enhances the resistance to oxidative degradation of MoS 2 , upon thermal treatment up to 900 C. The addition of the ionic antioxidant decreased dispersion stability in non-polar solvent, suggesting decreased compatibility with non-polar systems. Using simple chemical methods, the ability to generate tailored multidimensional layered materials with unique macroscopic properties is critical for numerous applications, including electrical devices, reinforced polymer composites, lithium ion capacitors, and chemical sensing.
Immobilization of WO{sub 3} or MoO{sub 3} on macroscopic silica fiber via CNFs template
Wu, Qiang Zhao, Li; Han, Ruobing
2013-08-01
Graphical abstract: Uniform immobilization of tungsten trioxide (WO{sub 3}) or molybdenum trioxide (MoO{sub 3}) on silica fiber was successfully achieved by using carbon nanofibers (CNFs) as template. FE-SEM coupled with XRD analysis confirmed the template effect and the existence of WO{sub 3} or MoO{sub 3} immobilized on silica fiber. It is expected that such materials with direct macroscopic shapes would hold promise as highly functionalized materials for potential practical applications, especially in photocatalysis. - Highlights: • WO{sub 3} or MoO{sub 3} with macroscopic shapes were successfully obtained. • WO{sub 3} and MoO{sub 3} immobilization depended on CNFs templates. • FE-SEM and XRD confirmed the structure and phase composition. - Abstract: Uniform immobilization of tungsten trioxide (WO{sub 3}) or molybdenum trioxide (MoO{sub 3}) on silica fiber was successfully achieved by using carbon nanofibers (CNFs) as template. Field emission scanning electron microscopy (FE-SEM), coupled with X-ray diffraction (XRD) analysis confirmed the template effect and the existence of WO{sub 3} or MoO{sub 3} immobilized on silica fiber. It is expected that such materials with direct macroscopic shapes would hold promise as highly functionalized materials for potential practical applications, especially in photocatalysis.
Chung, Hayoung; Choi, Joonmyung; Yun, Jung-Hoon; Cho, Maenghyo
2016-01-01
A liquid crystal network whose chromophores are functionalized by photochromic dye exhibits light-induced mechanical behaviour. As a result, the micro-scaled thermotropic traits of the network and the macroscopic phase behaviour are both influenced as light alternates the shape of the dyes. In this paper, we present an analysis of this photomechanical behaviour based on the proposed multiscale framework, which incorporates the molecular details of microstate evolution into a continuum-based understanding. The effects of trans-to-cis photoisomerization driven by actinic light irradiation are first examined using molecular dynamics simulations, and are compared against the predictions of the classical dilution model; this reveals certain characteristics of mesogenic interaction upon isomerization, followed by changes in the polymeric structure. We then upscale the thermotropic phase-related information with the aid of a nonlinear finite element analysis; macroscopic deflection with respect to the wide ranges of temperature and actinic light intensity are thereby examined, which reveals that the classical model underestimates the true deformation. This work therefore provides measures for analysing photomechanics in general by bridging the gap between the micro- and macro-scales. PMID:26828417
NASA Astrophysics Data System (ADS)
Chung, Hayoung; Choi, Joonmyung; Yun, Jung-Hoon; Cho, Maenghyo
2016-02-01
A liquid crystal network whose chromophores are functionalized by photochromic dye exhibits light-induced mechanical behaviour. As a result, the micro-scaled thermotropic traits of the network and the macroscopic phase behaviour are both influenced as light alternates the shape of the dyes. In this paper, we present an analysis of this photomechanical behaviour based on the proposed multiscale framework, which incorporates the molecular details of microstate evolution into a continuum-based understanding. The effects of trans-to-cis photoisomerization driven by actinic light irradiation are first examined using molecular dynamics simulations, and are compared against the predictions of the classical dilution model; this reveals certain characteristics of mesogenic interaction upon isomerization, followed by changes in the polymeric structure. We then upscale the thermotropic phase-related information with the aid of a nonlinear finite element analysis; macroscopic deflection with respect to the wide ranges of temperature and actinic light intensity are thereby examined, which reveals that the classical model underestimates the true deformation. This work therefore provides measures for analysing photomechanics in general by bridging the gap between the micro- and macro-scales.
The macroscopic polarization effect on thermal conductivity of binary nitrides
NASA Astrophysics Data System (ADS)
Sahoo, S. K.; Sahoo, B. K.; Sahoo, S.
2013-10-01
We theoretically investigate the effect of macroscopic polarization on phonon thermal conductivity of wurtzite (WZ) binary nitrides (AlN, GaN and InN). Our results show that macroscopic polarization contributes to the effective elastic constant of the wurtzite nitrides and modifies the phonon group velocity, Debye frequency, and Debye temperature. Using revised phonon velocity and Debye temperature, different phonon scattering rates and combined scattering rate are calculated as functions of the phonon frequency at room temperature. We estimate phonon thermal conductivity of binary nitrides using these modified parameters. The theoretical analysis shows that up to a certain temperature (different for AlN, GaN, and InN) the polarization effect acts as ill effect and reduces the thermal conductivity. However, after this temperature, the thermal conductivity is significantly enhanced by the polarization effect. The revised thermal conductivity at room temperature is found to be increased by 12% in GaN, 18% in InN and 20% in case of AlN due to macroscopic polarization, i.e., maximum polarization effect is observed in AlN and minimum in GaN. The method we have developed can be used for calculation of thermal energy in the active region of nitride optoelectronic devices.
Lozenge Tilings, Glauber Dynamics and Macroscopic Shape
NASA Astrophysics Data System (ADS)
Laslier, Benoît; Toninelli, Fabio Lucio
2015-09-01
We study the Glauber dynamics on the set of tilings of a finite domain of the plane with lozenges of side 1/ L. Under the invariant measure of the process (the uniform measure over all tilings), it is well known (Cohn et al. J Am Math Soc 14:297-346, 2001) that the random height function associated to the tiling converges in probability, in the scaling limit , to a non-trivial macroscopic shape minimizing a certain surface tension functional. According to the boundary conditions, the macroscopic shape can be either analytic or contain "frozen regions" (Arctic Circle phenomenon Cohn et al. N Y J Math 4:137-165, 1998; Jockusch et al. Random domino tilings and the arctic circle theorem, arXiv:math/9801068, 1998). It is widely conjectured, on the basis of theoretical considerations (Henley J Statist Phys 89:483-507, 1997; Spohn J Stat Phys 71:1081-1132, 1993), partial mathematical results (Caputo et al. Commun Math Phys 311:157-189, 2012; Wilson Ann Appl Probab 14:274-325, 2004) and numerical simulations for similar models (Destainville Phys Rev Lett 88:030601, 2002; cf. also the bibliography in Henley (J Statist Phys 89:483-507, 1997) and Wilson (Ann Appl Probab 14:274-325, 2004), that the Glauber dynamics approaches the equilibrium macroscopic shape in a time of order L 2+ o(1). In this work we prove this conjecture, under the assumption that the macroscopic equilibrium shape contains no "frozen region".
Berkeley Experiments on Superfluid Macroscopic Quantum Effects
Packard, Richard
2006-09-07
This paper provides a brief history of the evolution of the Berkeley experiments on macroscopic quantum effects in superfluid helium. The narrative follows the evolution of the experiments proceeding from the detection of single vortex lines to vortex photography to quantized circulation in 3He to Josephson effects and superfluid gyroscopes in both 4He and 3He.
Macroscopic Modeling of Polymer-Electrolyte Membranes
Weber, A.Z.; Newman, J.
2007-04-01
In this chapter, the various approaches for the macroscopic modeling of transport phenomena in polymer-electrolyte membranes are discussed. This includes general background and modeling methodologies, as well as exploration of the governing equations and some membrane-related topic of interest.
[Macroscopic hematuria in an adolescent in Chad].
Ballivet de Régloix, S; Maurin, O; Douniama Ondaï, C
2012-01-01
We report the case of a 16-year-old Chadian boy referred for chronic macroscopic hematuria and dysuria, diagnosed as urinary schistosomiasis, contracted while bathing in contaminated fresh water. The diagnostic approach and treatment in light of the limited resources available in Africa are described in detail.
Separation of the Microscopic and Macroscopic Domains
ERIC Educational Resources Information Center
Van Zandt, L. L.
1977-01-01
Examines the possibility of observing interference in quantum magnification experiments such as the celebrated "Schroedinger cat". Uses the possibility of observing interference for separating the realm of microscopic from macroscopic dynamics; estimates the dividing line to fall at system sizes of about 100 Daltons. (MLH)
Macroscopic behavior of ferrocholesteric liquid crystals and ferrocholesteric gels and elastomers.
Brand, Helmut R; Fink, Alexander; Pleiner, Harald
2015-06-01
We study the influence of macroscopic chirality on the macroscopic properties of superparamagnetic liquid crystals and gels. Specifically we derive macroscopic dynamic equations for ferrocholesteric low molecular weight (LMW) liquid crystals and for ferrocholesteric gels and elastomers in the local description using the director field as macroscopic variable. The magnetization is treated as a macroscopic dynamic degree of freedom and its coupling to all other macroscopic variables is examined in detail. We incorporate into our dynamic analysis terms that are linear in a magnetic field giving rise to a number of cross-coupling terms not possible otherwise. A number of properties that are unique to the class of systems studied arise. As an example for a static property we find a term in the generalized energy which is linear in the electric field and quadratic in the magnetic field. We find that applying a magnetic field to a ferrocholesteric can lead to reversible electric currents, heat currents and concentration currents, which change their sign with a sign change of macroscopic chirality. As an example of a rather intriguing dissipative dynamic contribution we point out that for ferrocholesterics and for ferrocholesteric gels and elastomers in a magnetic field extensional flow leads to electric and heat currents.
Microwave Diffraction Techniques from Macroscopic Crystal Models
ERIC Educational Resources Information Center
Murray, William Henry
1974-01-01
Discusses the construction of a diffractometer table and four microwave models which are built of styrofoam balls with implanted metallic reflecting spheres and designed to simulate the structures of carbon (graphite structure), sodium chloride, tin oxide, and palladium oxide. Included are samples of Bragg patterns and computer-analysis results.…
Connecting Pore Scale Dynamics to Macroscopic Models for Two-Fluid Phase Flow
NASA Astrophysics Data System (ADS)
McClure, J. E.; Dye, A. L.; Miller, C. T.; Gray, W. G.
2015-12-01
Imaging technologies such as computed micro-tomography (CMT) provide high resolution three-dimensional images of real porous medium systems that reveal the true geometric structure of fluid and solid phases. Simulation and analysis tools are essential to extract knowledge from this raw data, and can be applied in tandem to provide information that is otherwise inaccessible. Guidance from multi-scale averaging theory is used to develop a multi-scale analysis framework to determine phase connectivity and extract interfacial areas, curvatures, common line length, contact angle and the velocities of the interface and common curve. The approach is applied to analyze pore-scale dynamics based on a multiphase lattice Boltzmann method. Dense sets of simulations are performed to evaluate the equilibrium relationship between capillary pressure, saturation and interfacial area for several experimentally imaged porous media. The approach is also used study the evolution of macroscopic quantities under dynamic conditions, which is compared to the equilibrium data.
Modeling, Analysis, and Optimization Issues for Large Space Structures
NASA Technical Reports Server (NTRS)
Pinson, L. D. (Compiler); Amos, A. K. (Compiler); Venkayya, V. B. (Compiler)
1983-01-01
Topics concerning the modeling, analysis, and optimization of large space structures are discussed including structure-control interaction, structural and structural dynamics modeling, thermal analysis, testing, and design.
Proton irradiation effects on beryllium - A macroscopic assessment
NASA Astrophysics Data System (ADS)
Simos, Nikolaos; Elbakhshwan, Mohamed; Zhong, Zhong; Camino, Fernando
2016-10-01
Beryllium, due to its excellent neutron multiplication and moderation properties, in conjunction with its good thermal properties, is under consideration for use as plasma facing material in fusion reactors and as a very effective neutron reflector in fission reactors. While it is characterized by unique combination of structural, chemical, atomic number, and neutron absorption cross section it suffers, however, from irradiation generated transmutation gases such as helium and tritium which exhibit low solubility leading to supersaturation of the Be matrix and tend to precipitate into bubbles that coalesce and induce swelling and embrittlement thus degrading the metal and limiting its lifetime. Utilization of beryllium as a pion production low-Z target in high power proton accelerators has been sought both for its low Z and good thermal properties in an effort to mitigate thermos-mechanical shock that is expected to be induced under the multi-MW power demand. To assess irradiation-induced changes in the thermal and mechanical properties of Beryllium, a study focusing on proton irradiation damage effects has been undertaken using 200 MeV protons from the Brookhaven National Laboratory Linac and followed by a multi-faceted post-irradiation analysis that included the thermal and volumetric stability of irradiated beryllium, the stress-strain behavior and its ductility loss as a function of proton fluence and the effects of proton irradiation on the microstructure using synchrotron X-ray diffraction. The mimicking of high temperature irradiation of Beryllium via high temperature annealing schemes has been conducted as part of the post-irradiation study. This paper focuses on the thermal stability and mechanical property changes of the proton irradiated beryllium and presents results of the macroscopic property changes of Beryllium deduced from thermal and mechanical tests.
Interdisciplinary applications of network dynamics: From microscopic to Macroscopic
NASA Astrophysics Data System (ADS)
Jeong, Hawoong
``Everything touches everything.'' We are living in a connected world, which has been modeled successfully by complex networks. Ever since, network science becomes new paradigm for understanding our connected yet complex world. After investigating network structure itself, our focus naturally moved to dynamics of/on the network because our connected world is not static but dynamic. In this presentation, we will briefly review the historical development of network science and show some applications of network dynamics ranging from microscopic (metabolic engineering, PNAS, 104 13638) to macroscopic scale (price of anarchy in transportation network, Phys.Rev.Lett. 101 128701). Supported by National Research Foundation of Korea through Grant No. 2011-0028908.
Multivariate crash modeling for motor vehicle and non-motorized modes at the macroscopic level.
Lee, Jaeyoung; Abdel-Aty, Mohamed; Jiang, Ximiao
2015-05-01
Macroscopic traffic crash analyses have been conducted to incorporate traffic safety into long-term transportation planning. This study aims at developing a multivariate Poisson lognormal conditional autoregressive model at the macroscopic level for crashes by different transportation modes such as motor vehicle, bicycle, and pedestrian crashes. Many previous studies have shown the presence of common unobserved factors across different crash types. Thus, it was expected that adopting multivariate model structure would show a better modeling performance since it can capture shared unobserved features across various types. The multivariate model and univariate model were estimated based on traffic analysis zones (TAZs) and compared. It was found that the multivariate model significantly outperforms the univariate model. It is expected that the findings from this study can contribute to more reliable traffic crash modeling, especially when focusing on different modes. Also, variables that are found significant for each mode can be used to guide traffic safety policy decision makers to allocate resources more efficiently for the zones with higher risk of a particular transportation mode.
Macroscopic invisibility cloaking of visible light.
Chen, Xianzhong; Luo, Yu; Zhang, Jingjing; Jiang, Kyle; Pendry, John B; Zhang, Shuang
2011-01-01
Invisibility cloaks, which used to be confined to the realm of fiction, have now been turned into a scientific reality thanks to the enabling theoretical tools of transformation optics and conformal mapping. Inspired by those theoretical works, the experimental realization of electromagnetic invisibility cloaks has been reported at various electromagnetic frequencies. All the invisibility cloaks demonstrated thus far, however, have relied on nano- or micro-fabricated artificial composite materials with spatially varying electromagnetic properties, which limit the size of the cloaked region to a few wavelengths. Here, we report the first realization of a macroscopic volumetric invisibility cloak constructed from natural birefringent crystals. The cloak operates at visible frequencies and is capable of hiding, for a specific light polarization, three-dimensional objects of the scale of centimetres and millimetres. Our work opens avenues for future applications with macroscopic cloaking devices.
Macroscopic Quantum Superposition in Cavity Optomechanics
NASA Astrophysics Data System (ADS)
Liao, Jie-Qiao; Tian, Lin
Quantum superposition in mechanical systems is not only a key evidence of macroscopic quantum coherence, but can also be utilized in modern quantum technology. Here we propose an efficient approach for creating macroscopically distinct mechanical superposition states in a two-mode optomechanical system. Photon hopping between the two cavity-modes is modulated sinusoidally. The modulated photon tunneling enables an ultrastrong radiation-pressure force acting on the mechanical resonator, and hence significantly increases the mechanical displacement induced by a single photon. We present systematic studies on the generation of the Yurke-Stoler-like states in the presence of system dissipations. The state generation method is general and it can be implemented with either optomechanical or electromechanical systems. The authors are supported by the National Science Foundation under Award No. NSF-DMR-0956064 and the DARPA ORCHID program through AFOSR.
Macroscopic invisibility cloaking of visible light
Chen, Xianzhong; Luo, Yu; Zhang, Jingjing; Jiang, Kyle; Pendry, John B.; Zhang, Shuang
2011-01-01
Invisibility cloaks, which used to be confined to the realm of fiction, have now been turned into a scientific reality thanks to the enabling theoretical tools of transformation optics and conformal mapping. Inspired by those theoretical works, the experimental realization of electromagnetic invisibility cloaks has been reported at various electromagnetic frequencies. All the invisibility cloaks demonstrated thus far, however, have relied on nano- or micro-fabricated artificial composite materials with spatially varying electromagnetic properties, which limit the size of the cloaked region to a few wavelengths. Here, we report the first realization of a macroscopic volumetric invisibility cloak constructed from natural birefringent crystals. The cloak operates at visible frequencies and is capable of hiding, for a specific light polarization, three-dimensional objects of the scale of centimetres and millimetres. Our work opens avenues for future applications with macroscopic cloaking devices. PMID:21285954
Macroscopic invisibility cloak for visible light.
Zhang, Baile; Luo, Yuan; Liu, Xiaogang; Barbastathis, George
2011-01-21
Invisibility cloaks, a subject that usually occurs in science fiction and myths, have attracted wide interest recently because of their possible realization. The biggest challenge to true invisibility is known to be the cloaking of a macroscopic object in the broad range of wavelengths visible to the human eye. Here we experimentally solve this problem by incorporating the principle of transformation optics into a conventional optical lens fabrication with low-cost materials and simple manufacturing techniques. A transparent cloak made of two pieces of calcite is created. This cloak is able to conceal a macroscopic object with a maximum height of 2 mm, larger than 3500 free-space-wavelength, inside a transparent liquid environment. Its working bandwidth encompassing red, green, and blue light is also demonstrated.
Mathematical analysis of compressive/tensile molecular and nuclear structures
NASA Astrophysics Data System (ADS)
Wang, Dayu
Mathematical analysis in chemistry is a fascinating and critical tool to explain experimental observations. In this dissertation, mathematical methods to present chemical bonding and other structures for many-particle systems are discussed at different levels (molecular, atomic, and nuclear). First, the tetrahedral geometry of single, double, or triple carbon-carbon bonds gives an unsatisfying demonstration of bond lengths, compared to experimental trends. To correct this, Platonic solids and Archimedean solids were evaluated as atoms in covalent carbon or nitrogen bond systems in order to find the best solids for geometric fitting. Pentagonal solids, e.g. the dodecahedron and icosidodecahedron, give the best fit with experimental bond lengths; an ideal pyramidal solid which models covalent bonds was also generated. Second, the macroscopic compression/tension architectural approach was applied to forces at the molecular level, considering atomic interactions as compressive (repulsive) and tensile (attractive) forces. Two particle interactions were considered, followed by a model of the dihydrogen molecule (H2; two protons and two electrons). Dihydrogen was evaluated as two different types of compression/tension structures: a coaxial spring model and a ring model. Using similar methods, covalent diatomic molecules (made up of C, N, O, or F) were evaluated. Finally, the compression/tension model was extended to the nuclear level, based on the observation that nuclei with certain numbers of protons/neutrons (magic numbers) have extra stability compared to other nucleon ratios. A hollow spherical model was developed that combines elements of the classic nuclear shell model and liquid drop model. Nuclear structure and the trend of the "island of stability" for the current and extended periodic table were studied.
Polarization properties of macroscopic Bell states
Iskhakov, Timur Sh.; Chekhova, Maria V.; Leuchs, Gerd
2011-10-15
The four two-photon polarization Bell states are one of the main instruments in the toolbox of quantum optics and quantum information. In our experiment we produce their multiphoton counterparts, macroscopic Bell states. These are relevant to applications in quantum technologies because they provide efficient interactions with material quantum objects and with each other via nonlinear interactions. Furthermore, we study the polarization properties of these states using the concept of second-order degree of polarization and its higher-order generalization.
Can a macroscopic gyroscope feel torsion
NASA Technical Reports Server (NTRS)
Stoeger, W. R.; Yasskin, P. B.
1979-01-01
We demonstrate that for a large class of Lagrangian-based torsion theories a macroscopic gyroscope is insensitive to the torsion field: there can be no coupling of the torsion to the gyroscope's angular momentum of rotation. To detect torsion a polarized system with a net elementary particle spin is needed. These conclusions are evident from the conservation laws, which form the basis for deriving the equations of motion.
NASA Astrophysics Data System (ADS)
Gawad, J.; Khairullah, Md; Roose, D.; Van Bael, A.
2016-08-01
Multi-scale simulations are computationally expensive if a two-way coupling is employed. In the context of sheet metal forming simulations, a fine-scale representative volume element (RVE) crystal plasticity (CP) model would supply the Finite Element analysis with plastic properties, taking into account the evolution of crystallographic texture and other microstructural features. The main bottleneck is that the fine-scale model must be evaluated at virtually every integration point in the macroscopic FE mesh. We propose to address this issue by exploiting a verifiable assumption that fine-scale state variables of similar RVEs, as well as the derived properties, subjected to similar macroscopic boundary conditions evolve along nearly identical trajectories. Furthermore, the macroscopic field variables primarily responsible for the evolution of fine-scale state variables often feature local quasi-homogeneities. Adjacent integration points in the FE mesh can be then clustered together in the regions where the field responsible for the evolution shows low variance. This way the fine-scale evolution is tracked only at a limited number of material points and the derived plastic properties are propagated to the surrounding integration points subjected to similar deformation. Optimal configurations of the clusters vary in time as the local deformation conditions may change during the forming process, so the clusters must be periodically adapted. We consider two operations on the clusters of integration points: splitting (refinement) and merging (unrefinement). The concept is tested in the Hierarchical Multi-Scale (HMS) framework [1] that computes macroscopic deformations by means of the FEM, whereas the micro-structural evolution at the individual FE integration points is predicted by a CP model. The HMS locally and adaptively approximates homogenized stress responses of the CP model by means of analytical plastic potential or yield criterion function. Our earlier work
Toward a macroscopic parameterization of iceberg calving
NASA Astrophysics Data System (ADS)
Amundson, J. M.
2014-12-01
Parameterization of iceberg calving for prognostic glacier and ice sheet models remains a major challenge due to a poor understanding of the physical processes governing calving. Here, I propose a semi-empirical, macroscopic parameterization of calving that ignores the complex physics of the glacier-ocean interface, can be applied to any calving margin, and is easy to implement with very little computational cost. To test the parameterization, I apply it to a one-dimensional flowline model of an Alaskan-style tidewater glacier and subject the model to various climatic forcings. The model produces results that are roughly consistent with observations, i.e., rapid retreat and flow acceleration through an overdeepening over decades and slow re-advance over millenia. Model results are compared to the previously proposed water depth, height above flotation, and crevasse-depth calving parameterizations to show that they are consistent with the macroscopic parameterization under certain conditions. Although there remains a great deal of uncertainty in the exact form of the macroscopic parameterization, it does appear to be a promising and simple way to model the glacier-ocean boundary.
NASA Astrophysics Data System (ADS)
Muramatsu, M.; Terada, K.; Kawada, T.; Yashiro, K.; Takahashi, K.; Takase, S.
2015-10-01
In order to perform stress analyses of a solid oxide fuel cell (SOFC) under operation, we propose a characterization method of its time-varying macroscopic electro-chemo-mechanical behavior of electrodes by considering the time-varying geometries of anode microstructures due to Ni-sintering. The phase-field method is employed to simulate the micro-scale morphology change with time, from which the time-variation of the amount of triple-phase boundaries is directly predicted. Then, to evaluate the time-variation of the macroscopic oxygen ionic and electronic conductivities and the inelastic properties of the anode electrode, numerical material tests based on the homogenization method are conducted for each state of sintered microstructures. In these homogenization analyses, we also have to consider the dependencies of the properties of constituent materials on the temperature and/or the oxygen potential that is supposed to change within an operation period. To predict the oxygen potential distribution in an overall SOFC structure under long-period operation, which determines reduction-induced expansive/contractive deformation of oxide materials, an unsteady problem of macroscopic oxygen ionic and electronic conductions is solved. Using the calculated stress-free strains and the homogenized mechanical properties, both of which depend on the operational environment, we carry out the macroscopic stress analysis of the SOFC.
Schulze-Zachau, Felix; Nagel, Eva; Engelhardt, Kathrin; Stoyanov, Stefan; Gochev, Georgi; Khristov, Khr.; Mileva, Elena; Exerowa, Dotchi; Miller, Reinhard; Peukert, Wolfgang
2016-01-01
β-Lactoglobulin (BLG) adsorption layers at air–water interfaces were studied in situ with vibrational sum-frequency generation (SFG), tensiometry, surface dilatational rheology and ellipsometry as a function of bulk Ca2+ concentration. The relation between the interfacial molecular structure of adsorbed BLG and the interactions with the supporting electrolyte is additionally addressed on higher length scales along the foam hierarchy – from the ubiquitous air–water interface through thin foam films to macroscopic foam. For concentrations <1 mM, a strong decrease in SFG intensity from O–H stretching bands and a slight increase in layer thickness and surface pressure are observed. A further increase in Ca2+ concentrations above 1 mM causes an apparent change in the polarity of aromatic C–H stretching vibrations from interfacial BLG which we associate to a charge reversal at the interface. Foam film measurements show formation of common black films at Ca2+ concentrations above 1 mM due to considerable decrease of the stabilizing electrostatic disjoining pressure. These observations also correlate with a minimum in macroscopic foam stability. For concentrations >30 mM Ca2+, micrographs of foam films show clear signatures of aggregates which tend to increase the stability of foam films. Here, the interfacial layers have a higher surface dilatational elasticity. In fact, macroscopic foams formed from BLG dilutions with high Ca2+ concentrations where aggregates and interfacial layers with higher elasticity are found, showed the highest stability with much smaller bubble sizes. PMID:27337699
Fourier Analysis and Structure Determination--Part III: X-ray Crystal Structure Analysis.
ERIC Educational Resources Information Center
Chesick, John P.
1989-01-01
Discussed is single crystal X-ray crystal structure analysis. A common link between the NMR imaging and the traditional X-ray crystal structure analysis is reported. Claims that comparisons aid in the understanding of both techniques. (MVL)
Macroscopic Subdivision of Silica Aerogel Collectors for Sample Return Missions
Ishii, H A; Bradley, J P
2005-09-14
Silica aerogel collector tiles have been employed for the collection of particles in low Earth orbit and, more recently, for the capture of cometary particles by NASA's Stardust mission. Reliable, reproducible methods for cutting these and future collector tiles from sample return missions are necessary to maximize the science output from the extremely valuable embedded particles. We present a means of macroscopic subdivision of collector tiles by generating large-scale cuts over several centimeters in silica aerogel with almost no material loss. The cut surfaces are smooth and optically clear allowing visual location of particles for analysis and extraction. This capability is complementary to the smaller-scale cutting capabilities previously described [Westphal (2004), Ishii (2005a, 2005b)] for removing individual impacts and particulate debris in tiny aerogel extractions. Macroscopic cuts enable division and storage or distribution of portions of aerogel tiles for immediate analysis of samples by certain techniques in situ or further extraction of samples suited for other methods of analysis.
Structural analysis techniqes for remote sensing
NASA Technical Reports Server (NTRS)
Shapiro, L. G.
1982-01-01
The structural analysis of remotely sensed imagery is defined and basic techniques for implementing the process are described. Structural analysis uses knowledge of the properties of an entity, its parts and their relationships, and the relationships in which it participates at a higher level to locate and recognize objects in a visual scene. The representation of structural knowledge, the development of algorithms for using the knowledge to help analyze an image, and techniques for storage and retrieval of relational models are addressed.
Probabilistic structural analysis by extremum methods
NASA Technical Reports Server (NTRS)
Nafday, Avinash M.
1990-01-01
The objective is to demonstrate discrete extremum methods of structural analysis as a tool for structural system reliability evaluation. Specifically, linear and multiobjective linear programming models for analysis of rigid plastic frames under proportional and multiparametric loadings, respectively, are considered. Kinematic and static approaches for analysis form a primal-dual pair in each of these models and have a polyhedral format. Duality relations link extreme points and hyperplanes of these polyhedra and lead naturally to dual methods for system reliability evaluation.
[Macroscopic Functional Networks of the Human Brain when Viewing and Recalling Short Videos].
Verkhlyutov, V M; Sokolov, P A; Ushakov, V L; Velichkovsky, B M
2015-01-01
Macroscopic functional network of the human brain were identified by use of the independent component analysis (ICA) of fMRI while viewing and imaging/recalling stories. The networks were relatively stable in structure, but had a specific dynamics in different experimental conditions. When comparing detected networks with previously detected resting state networks it was found that they coincide on localization. We. discovered also the specificity of activating the peripheral and central parts of retinotopic projections in the visual cortex. The peripheral areas were activated during subject viewing and imaging/recalling. On the contrary, the central departments strengthened their activation when viewing and reduced activity during the imaging/recalling. PMID:26281231
Ding, W; Li, A; Wu, J; Yang, Z; Meng, Y; Wang, S; Gong, H
2013-08-01
Acquiring a whole mouse brain at the micrometer scale is a complex, continuous and time-consuming process. Because of defects caused by sample preparation and microscopy, the acquired image data sets suffer from various macroscopic density artefacts that worsen the image quality. We have to develop the available preprocessing methods to improve image quality by removing the artefacts that effect cell segmentation, vascular tracing and visualization. In this study, a set of automatic artefact removal methods is proposed for images obtained by tissue staining and optical microscopy. These methods significantly improve the complicated images that contain various structures, including cells and blood vessels. The whole mouse brain data set with Nissl staining was tested, and the intensity of the processed images was uniformly distributed throughout different brain areas. Furthermore, the processed image data set with its uniform brightness and high quality is now a fundamental atlas for image analysis, including cell segmentation, vascular tracing and visualization.
Structural analysis of ultra-high speed aircraft structural components
NASA Technical Reports Server (NTRS)
Lenzen, K. H.; Siegel, W. H.
1977-01-01
The buckling characteristics of a hypersonic beaded skin panel were investigated under pure compression with boundary conditions similar to those found in a wing mounted condition. The primary phases of analysis reported include: (1) experimental testing of the panel to failure; (2) finite element structural analysis of the beaded panel with the computer program NASTRAN; and (3) summary of the semiclassical buckling equations for the beaded panel under purely compressive loads. A comparison of each of the analysis methods is also included.
Automating Structural Analysis of Spacecraft Vehicles
NASA Technical Reports Server (NTRS)
Hrinda, Glenn A.
2004-01-01
A major effort within NASA's vehicle analysis discipline has been to automate structural analysis and sizing optimization during conceptual design studies of advanced spacecraft. Traditional spacecraft structural sizing has involved detailed finite element analysis (FEA) requiring large degree-of-freedom (DOF) finite element models (FEM). Creation and analysis of these models can be time consuming and limit model size during conceptual designs. The goal is to find an optimal design that meets the mission requirements but produces the lightest structure. A structural sizing tool called HyperSizer has been successfully used in the conceptual design phase of a reusable launch vehicle and planetary exploration spacecraft. The program couples with FEA to enable system level performance assessments and weight predictions including design optimization of material selections and sizing of spacecraft members. The software's analysis capabilities are based on established aerospace structural methods for strength, stability and stiffness that produce adequately sized members and reliable structural weight estimates. The software also helps to identify potential structural deficiencies early in the conceptual design so changes can be made without wasted time. HyperSizer's automated analysis and sizing optimization increases productivity and brings standardization to a systems study. These benefits will be illustrated in examining two different types of conceptual spacecraft designed using the software. A hypersonic air breathing, single stage to orbit (SSTO), reusable launch vehicle (RLV) will be highlighted as well as an aeroshell for a planetary exploration vehicle used for aerocapture at Mars. By showing the two different types of vehicles, the software's flexibility will be demonstrated with an emphasis on reducing aeroshell structural weight. Member sizes, concepts and material selections will be discussed as well as analysis methods used in optimizing the structure
Micro and macroscopic investigation to quantify tillage impact on soil hydrodynamic behaviour
NASA Astrophysics Data System (ADS)
Beckers, E.; Roisin, C.; Plougonven, E.; Deraedt, D.; Léonard, A.; Degré, A.
2012-04-01
Nowadays, tillage simplification is an increasing practice. Many advantages are cited in the literature, such as energy saving, soil conservation etc. Agricultural management practices influence soil structure, but consequent changes in soil hydrodynamic behaviour at the field scale are still not well understood. Many studies focus only on macroscopic measurements which do not provide mechanistic explanations. Moreover, research shows divergent conclusions over structure modification. The aim of this work is to fill this gap by quantifying soil structure modification depending on tillage intensity through both macroscopic and microscopic measurements, the latter improving our comprehension of the fundamental mechanisms involved. Our experiment takes place in Gentinnes (Walloon Brabant, Belgium), on a field organized in a Latin square scheme. Since 2004, plots have been cultivated in conventional tillage (CT) or in reduced tillage (RT). The latter consists in sowing after stubble ploughing of about 10cm. The crop rotation is sugar beet followed by winter wheat. The soil is mainly composed of silt loam and can be classified as a Luvisol. Macroscopic investigations consist in establishing pF and K(h) curves and 3D soil strength profiles. At the microscale, 3D morphologic parameters are measured using X-ray microtomography. Because of the variation of working depth between management practices (10cm for RT vs. 25cm for CT), two horizons were investigated: H1 between 0-10cm and H2 between 12-25cm. 3D soil strength profiles were established thanks to a fully automated penetrometer (30° angle cone with a base area of 10mm2) which covered a 160 × 80cm2 area with 5cm spacing between neighbouring points. At each node, penetration was performed and soil strength measurements were collected every 1cm from 5 to 55cm depth. K(h) curves were provided by 20cm diameter tension-infiltrometer measurements (Eijkelkamp Agrisearch Equipment). Undisturbed soil samples were removed from
Mass spectrometry for pectin structure analysis.
Ralet, Marie-Christine; Lerouge, Patrice; Quéméner, Bernard
2009-09-28
Pectin are extremely complex biopolymers made up of different structural domains. Enzymatic degradation followed by purification and structural analysis of the degradation products proved to be efficient tools for the understanding of pectin fine structure, including covalent interactions between pectic structural domains or with other cell wall polysaccharides. Due to its high sensitivity, high throughput and capacity to analyze mixtures, mass spectrometry has gained more and more importance as a tool for oligosaccharides structural characterization in the past 10 years. This review will focus on the combined use of mass spectrometry and enzymatic digestion for pectins structural characterization. PMID:19058795
Dai, Zhaohe; Liu, Luqi; Qi, Xiaoying; Kuang, Jun; Wei, Yueguang; Zhu, Hongwei; Zhang, Zhong
2016-01-01
Efficient assembly of carbon nanotube (CNT) based cellular solids with appropriate structure is the key to fully realize the potential of individual nanotubes in macroscopic architecture. In this work, the macroscopic CNT sponge consisting of randomly interconnected individual carbon nanotubes was grown by CVD, exhibiting a combination of super-elasticity, high strength to weight ratio, fatigue resistance, thermo-mechanical stability and electro-mechanical stability. To deeply understand such extraordinary mechanical performance compared to that of conventional cellular materials and other nanostructured cellular architectures, a thorough study on the response of this CNT-based spongy structure to compression is conducted based on classic elastic theory. The strong inter-tube bonding between neighboring nanotubes is examined, believed to play a critical role in the reversible deformation such as bending and buckling without structural collapse under compression. Based on in-situ scanning electron microscopy observation and nanotube deformation analysis, structural evolution (completely elastic bending-buckling transition) of the carbon nanotubes sponges to deformation is proposed to clarify their mechanical properties and nonlinear electromechanical coupling behavior. PMID:26732143
NASA Astrophysics Data System (ADS)
Dai, Zhaohe; Liu, Luqi; Qi, Xiaoying; Kuang, Jun; Wei, Yueguang; Zhu, Hongwei; Zhang, Zhong
2016-01-01
Efficient assembly of carbon nanotube (CNT) based cellular solids with appropriate structure is the key to fully realize the potential of individual nanotubes in macroscopic architecture. In this work, the macroscopic CNT sponge consisting of randomly interconnected individual carbon nanotubes was grown by CVD, exhibiting a combination of super-elasticity, high strength to weight ratio, fatigue resistance, thermo-mechanical stability and electro-mechanical stability. To deeply understand such extraordinary mechanical performance compared to that of conventional cellular materials and other nanostructured cellular architectures, a thorough study on the response of this CNT-based spongy structure to compression is conducted based on classic elastic theory. The strong inter-tube bonding between neighboring nanotubes is examined, believed to play a critical role in the reversible deformation such as bending and buckling without structural collapse under compression. Based on in-situ scanning electron microscopy observation and nanotube deformation analysis, structural evolution (completely elastic bending-buckling transition) of the carbon nanotubes sponges to deformation is proposed to clarify their mechanical properties and nonlinear electromechanical coupling behavior.
Dai, Zhaohe; Liu, Luqi; Qi, Xiaoying; Kuang, Jun; Wei, Yueguang; Zhu, Hongwei; Zhang, Zhong
2016-01-01
Efficient assembly of carbon nanotube (CNT) based cellular solids with appropriate structure is the key to fully realize the potential of individual nanotubes in macroscopic architecture. In this work, the macroscopic CNT sponge consisting of randomly interconnected individual carbon nanotubes was grown by CVD, exhibiting a combination of super-elasticity, high strength to weight ratio, fatigue resistance, thermo-mechanical stability and electro-mechanical stability. To deeply understand such extraordinary mechanical performance compared to that of conventional cellular materials and other nanostructured cellular architectures, a thorough study on the response of this CNT-based spongy structure to compression is conducted based on classic elastic theory. The strong inter-tube bonding between neighboring nanotubes is examined, believed to play a critical role in the reversible deformation such as bending and buckling without structural collapse under compression. Based on in-situ scanning electron microscopy observation and nanotube deformation analysis, structural evolution (completely elastic bending-buckling transition) of the carbon nanotubes sponges to deformation is proposed to clarify their mechanical properties and nonlinear electromechanical coupling behavior.
Dai, Zhaohe; Liu, Luqi; Qi, Xiaoying; Kuang, Jun; Wei, Yueguang; Zhu, Hongwei; Zhang, Zhong
2016-01-01
Efficient assembly of carbon nanotube (CNT) based cellular solids with appropriate structure is the key to fully realize the potential of individual nanotubes in macroscopic architecture. In this work, the macroscopic CNT sponge consisting of randomly interconnected individual carbon nanotubes was grown by CVD, exhibiting a combination of super-elasticity, high strength to weight ratio, fatigue resistance, thermo-mechanical stability and electro-mechanical stability. To deeply understand such extraordinary mechanical performance compared to that of conventional cellular materials and other nanostructured cellular architectures, a thorough study on the response of this CNT-based spongy structure to compression is conducted based on classic elastic theory. The strong inter-tube bonding between neighboring nanotubes is examined, believed to play a critical role in the reversible deformation such as bending and buckling without structural collapse under compression. Based on in-situ scanning electron microscopy observation and nanotube deformation analysis, structural evolution (completely elastic bending-buckling transition) of the carbon nanotubes sponges to deformation is proposed to clarify their mechanical properties and nonlinear electromechanical coupling behavior. PMID:26732143
Structural analysis consultation using artificial intelligence
NASA Technical Reports Server (NTRS)
Melosh, R. J.; Marcal, P. V.; Berke, L.
1978-01-01
The primary goal of consultation is definition of the best strategy to deal with a structural engineering analysis objective. The knowledge base to meet the need is designed to identify the type of numerical analysis, the needed modeling detail, and specific analysis data required. Decisions are constructed on the basis of the data in the knowledge base - material behavior, relations between geometry and structural behavior, measures of the importance of time and temperature changes - and user supplied specifics characteristics of the spectrum of analysis types, the relation between accuracy and model detail on the structure, its mechanical loadings, and its temperature states. Existing software demonstrated the feasibility of the approach, encompassing the 36 analysis classes spanning nonlinear, temperature affected, incremental analyses which track the behavior of structural systems.
Transient Macroscopic Chemistry in the DSMC Method
NASA Astrophysics Data System (ADS)
Goldsworthy, M. J.; Macrossan, M. N.; Abdel-Jawad, M.
2008-12-01
In the Direct Simulation Monte Carlo method, a combination of statistical and deterministic procedures applied to a finite number of `simulator' particles are used to model rarefied gas-kinetic processes. Traditionally, chemical reactions are modelled using information from specific colliding particle pairs. In the Macroscopic Chemistry Method (MCM), the reactions are decoupled from the specific particle pairs selected for collisions. Information from all of the particles within a cell is used to determine a reaction rate coefficient for that cell. MCM has previously been applied to steady flow DSMC simulations. Here we show how MCM can be used to model chemical kinetics in DSMC simulations of unsteady flow. Results are compared with a collision-based chemistry procedure for two binary reactions in a 1-D unsteady shock-expansion tube simulation and during the unsteady development of 2-D flow through a cavity. For the shock tube simulation, close agreement is demonstrated between the two methods for instantaneous, ensemble-averaged profiles of temperature and species mole fractions. For the cavity flow, a high degree of thermal non-equilibrium is present and non-equilibrium reaction rate correction factors are employed in MCM. Very close agreement is demonstrated for ensemble averaged mole fraction contours predicted by the particle and macroscopic methods at three different flow-times. A comparison of the accumulated number of net reactions per cell shows that both methods compute identical numbers of reaction events. For the 2-D flow, MCM required similar CPU and memory resources to the particle chemistry method. The Macroscopic Chemistry Method is applicable to any general DSMC code using any viscosity or non-reacting collision models and any non-reacting energy exchange models. MCM can be used to implement any reaction rate formulations, whether these be from experimental or theoretical studies.
Compressor Has No Moving Macroscopic Parts
NASA Technical Reports Server (NTRS)
Gasser, Max
1995-01-01
Compressor containing no moving macroscopic parts functions by alternating piston and valve actions of successive beds of magnetic particles. Fabricated easily because no need for precisely fitting parts rotating or sliding on each other. Also no need for lubricant fluid contaminating fluid to be compressed. Compressor operates continuously, eliminating troublesome on/off cycling of other compressors, and decreasing consumption of energy. Phased cells push fluid from bottom to top, adding increments of pressure. Each cell contains magnetic powder particles loose when electromagnet coil deenergized, but tightly packed when coil energized.
Static Nonlinear Analysis In Concrete Structures
Hemmati, Ali
2008-07-08
Push-over analysis is a simple and applied approach which can be used for estimation of demand responses influenced by earthquake stimulations. The analysis is non-linear static analysis of the structure affected under increasing lateral loads and specifying the displacement--load diagram or structure capacity curve, draw the curve the base shear values and lateral deflection on the roof level of the building will be used. However, for estimation of the real behavior of the structure against earthquake, the non-linear dynamic analysis approaches and various accelerographs should be applied. Of course it should be noted that this approach especially in relation with tall buildings is complex and time consuming. In the article, the different patterns of lateral loading in push-over analysis have been compared with non-linear dynamic analysis approach so that the results represented accordingly. The researches indicated the uniformly--distributed loading is closer to real status.
NAPS: Network Analysis of Protein Structures
Chakrabarty, Broto; Parekh, Nita
2016-01-01
Traditionally, protein structures have been analysed by the secondary structure architecture and fold arrangement. An alternative approach that has shown promise is modelling proteins as a network of non-covalent interactions between amino acid residues. The network representation of proteins provide a systems approach to topological analysis of complex three-dimensional structures irrespective of secondary structure and fold type and provide insights into structure-function relationship. We have developed a web server for network based analysis of protein structures, NAPS, that facilitates quantitative and qualitative (visual) analysis of residue–residue interactions in: single chains, protein complex, modelled protein structures and trajectories (e.g. from molecular dynamics simulations). The user can specify atom type for network construction, distance range (in Å) and minimal amino acid separation along the sequence. NAPS provides users selection of node(s) and its neighbourhood based on centrality measures, physicochemical properties of amino acids or cluster of well-connected residues (k-cliques) for further analysis. Visual analysis of interacting domains and protein chains, and shortest path lengths between pair of residues are additional features that aid in functional analysis. NAPS support various analyses and visualization views for identifying functional residues, provide insight into mechanisms of protein folding, domain-domain and protein–protein interactions for understanding communication within and between proteins. URL:http://bioinf.iiit.ac.in/NAPS/. PMID:27151201
NAPS: Network Analysis of Protein Structures.
Chakrabarty, Broto; Parekh, Nita
2016-07-01
Traditionally, protein structures have been analysed by the secondary structure architecture and fold arrangement. An alternative approach that has shown promise is modelling proteins as a network of non-covalent interactions between amino acid residues. The network representation of proteins provide a systems approach to topological analysis of complex three-dimensional structures irrespective of secondary structure and fold type and provide insights into structure-function relationship. We have developed a web server for network based analysis of protein structures, NAPS, that facilitates quantitative and qualitative (visual) analysis of residue-residue interactions in: single chains, protein complex, modelled protein structures and trajectories (e.g. from molecular dynamics simulations). The user can specify atom type for network construction, distance range (in Å) and minimal amino acid separation along the sequence. NAPS provides users selection of node(s) and its neighbourhood based on centrality measures, physicochemical properties of amino acids or cluster of well-connected residues (k-cliques) for further analysis. Visual analysis of interacting domains and protein chains, and shortest path lengths between pair of residues are additional features that aid in functional analysis. NAPS support various analyses and visualization views for identifying functional residues, provide insight into mechanisms of protein folding, domain-domain and protein-protein interactions for understanding communication within and between proteins. URL:http://bioinf.iiit.ac.in/NAPS/. PMID:27151201
Structural analysis of stratocumulus convection
NASA Technical Reports Server (NTRS)
Siems, S. T.; Baker, M. B.; Bretherton, C. S.
1990-01-01
The 1 and 20 Hz data are examined from the Electra flights made on July 5, 1987. The flight legs consisted of seven horizontal turbulent legs at the inversion, midcloud, and below clouds, plus 4 soundings made within the same period. The Rosemont temperature sensor and the top and bottom dewpoint sensors were used to measure temperature and humidity at 1 Hz. Inversion structure and entrainment; local dynamics and large scale forcing; convective elements; and decoupling of cloud and subcloud are discussed in relationship to the results of the Electra flight.
Thermal and structural analysis of Hermes
NASA Astrophysics Data System (ADS)
Petiau, C.
1989-08-01
After a brief recap of Hermes TPS and structure principles, we present the organization of thermal and structural analysis of the Hermes project, and we describe the way to resolve the problems of connections between calculations performed by the different Hermes partners. We describe in detail the interactions between the general model of TPS, used for global dimensioning of insulation, and refined thermal models giving an accurate temperature map inside details of "hot" and "cold" structures. The organization for structural analysis is based on a finite element general model which supports preliminary design, loads and vibration analyses. Boundary conditions for refined subpart analyses are cut to size, into the general model by a super element technique. This process involves the use by all partners of efficient computer codes, in the field of structural analysis and optimization integrated with CAD; for this Dassault proposes as a reference: the CATIA-ELFINI system.
Semantic Antinomies and Deep Structure Analysis
ERIC Educational Resources Information Center
Zuber, Ryszard
1975-01-01
This article discusses constructions known as semantic antinomies, that is, the paradoxical results of false presuppositions, and how they can be dealt with by means of deep structure analysis. See FL 508 186 for availability. (CLK)
Macroscopic theory for capillary-pressure hysteresis.
Athukorallage, Bhagya; Aulisa, Eugenio; Iyer, Ram; Zhang, Larry
2015-03-01
In this article, we present a theory of macroscopic contact angle hysteresis by considering the minimization of the Helmholtz free energy of a solid-liquid-gas system over a convex set, subject to a constant volume constraint. The liquid and solid surfaces in contact are assumed to adhere weakly to each other, causing the interfacial energy to be set-valued. A simple calculus of variations argument for the minimization of the Helmholtz energy leads to the Young-Laplace equation for the drop surface in contact with the gas and a variational inequality that yields contact angle hysteresis for advancing/receding flow. We also show that the Young-Laplace equation with a Dirichlet boundary condition together with the variational inequality yields a basic hysteresis operator that describes the relationship between capillary pressure and volume. We validate the theory using results from the experiment for a sessile macroscopic drop. Although the capillary effect is a complex phenomenon even for a droplet as various points along the contact line might be pinned, the capillary pressure and volume of the drop are scalar variables that encapsulate the global quasistatic energy information for the entire droplet. Studying the capillary pressure versus volume relationship greatly simplifies the understanding and modeling of the phenomenon just as scalar magnetic hysteresis graphs greatly aided the modeling of devices with magnetic materials.
Macroscopic theory for capillary-pressure hysteresis.
Athukorallage, Bhagya; Aulisa, Eugenio; Iyer, Ram; Zhang, Larry
2015-03-01
In this article, we present a theory of macroscopic contact angle hysteresis by considering the minimization of the Helmholtz free energy of a solid-liquid-gas system over a convex set, subject to a constant volume constraint. The liquid and solid surfaces in contact are assumed to adhere weakly to each other, causing the interfacial energy to be set-valued. A simple calculus of variations argument for the minimization of the Helmholtz energy leads to the Young-Laplace equation for the drop surface in contact with the gas and a variational inequality that yields contact angle hysteresis for advancing/receding flow. We also show that the Young-Laplace equation with a Dirichlet boundary condition together with the variational inequality yields a basic hysteresis operator that describes the relationship between capillary pressure and volume. We validate the theory using results from the experiment for a sessile macroscopic drop. Although the capillary effect is a complex phenomenon even for a droplet as various points along the contact line might be pinned, the capillary pressure and volume of the drop are scalar variables that encapsulate the global quasistatic energy information for the entire droplet. Studying the capillary pressure versus volume relationship greatly simplifies the understanding and modeling of the phenomenon just as scalar magnetic hysteresis graphs greatly aided the modeling of devices with magnetic materials. PMID:25646688
A Macroscopic Realization of the Weak Interaction
NASA Technical Reports Server (NTRS)
Nishimori, Arito
2003-01-01
A.J.Leggett suggested in 1977 that a permanent electric dipole moment due to the parity-nonconserving electron-nucleon interaction, even though it is extremely small, could be measured in the superfluid He-3 B because the moment should be proportional to the size of the sample in this system. If this moment is observed, it will be the first example of a macroscopic realization of the weak interaction. In our planned experiments, a high electric field of up to 6 kV/cm is applied between two parallel electrodes in the He-3 sample. We expect to observe the NMR frequency of the lowest-lying spin-wave mode trapped by the liquid crystal-like texture of the B phase rotation axis in our geometry. The interaction of the electric field and the macroscopic permanent electric dipole moment, which is oriented along the rotation axis, will cause a small change in the texture and hence a small increase in the frequency of the spin wave mode. Besides the basic ideas, we present the purpose and the design of our first cell that is under construction.
Macroscopic strain potentials in nonlinear porous materials
NASA Astrophysics Data System (ADS)
Yi, Liu; Zhuping, Huang
2003-02-01
By taking a hollow sphere as a representative volume element (RVE), the macroscopic strain potentials of porous materials with power-law incompressible matrix are studied in this paper. According to the principles of the minimum potential energy in nonlinear elasticity and the variational procedure, static admissible stress fields and kinematic admissible displacement fields are constructed, and hence the upper and the lower bounds of the macroscopic strain potential are obtained. The bounds given in the present paper differ so slightly that they both provide perfect approximations of the exact strain potential of the studied porous materials. It is also found that the upper bound proposed by previous authors is much higher than the present one, and the lower bounds given by Cocks is much lower. Moreover, the present calculation is also compared with the variational lower bound of Ponte Castañeda for statistically isotropic porous materials. Finally, the validity of the hollow spherical RVE for the studied nonlinear porous material is discussed by the difference between the present numerical results and the Cocks bound.
Measurement contextuality is implied by macroscopic realism
Chen Zeqian; Montina, A.
2011-04-15
Ontological theories of quantum mechanics provide a realistic description of single systems by means of well-defined quantities conditioning the measurement outcomes. In order to be complete, they should also fulfill the minimal condition of macroscopic realism. Under the assumption of outcome determinism and for Hilbert space dimension greater than 2, they were all proved to be contextual for projective measurements. In recent years a generalized concept of noncontextuality was introduced that applies also to the case of outcome indeterminism and unsharp measurements. It was pointed out that the Beltrametti-Bugajski model is an example of measurement noncontextual indeterminist theory. Here we provide a simple proof that this model is the only one with such a feature for projective measurements and Hilbert space dimension greater than 2. In other words, there is no extension of quantum theory providing more accurate predictions of outcomes and simultaneously preserving the minimal labeling of events through projective operators. As a corollary, noncontextuality for projective measurements implies noncontextuality for unsharp measurements. By noting that the condition of macroscopic realism requires an extension of quantum theory, unless a breaking of unitarity is invoked, we arrive at the conclusion that the only way to solve the measurement problem in the framework of an ontological theory is by relaxing the hypothesis of measurement noncontextuality in its generalized sense.
Deterministic Creation of Macroscopic Cat States
Lombardo, Daniel; Twamley, Jason
2015-01-01
Despite current technological advances, observing quantum mechanical effects outside of the nanoscopic realm is extremely challenging. For this reason, the observation of such effects on larger scale systems is currently one of the most attractive goals in quantum science. Many experimental protocols have been proposed for both the creation and observation of quantum states on macroscopic scales, in particular, in the field of optomechanics. The majority of these proposals, however, rely on performing measurements, making them probabilistic. In this work we develop a completely deterministic method of macroscopic quantum state creation. We study the prototypical optomechanical Membrane In The Middle model and show that by controlling the membrane’s opacity, and through careful choice of the optical cavity initial state, we can deterministically create and grow the spatial extent of the membrane’s position into a large cat state. It is found that by using a Bose-Einstein condensate as a membrane high fidelity cat states with spatial separations of up to ∼300 nm can be achieved. PMID:26345157
Structural Dynamics and Data Analysis
NASA Technical Reports Server (NTRS)
Luthman, Briana L.
2013-01-01
This project consists of two parts, the first will be the post-flight analysis of data from a Delta IV launch vehicle, and the second will be a Finite Element Analysis of a CubeSat. Shock and vibration data was collected on WGS-5 (Wideband Global SATCOM- 5) which was launched on a Delta IV launch vehicle. Using CAM (CAlculation with Matrices) software, the data is to be plotted into Time History, Shock Response Spectrum, and SPL (Sound Pressure Level) curves. In this format the data is to be reviewed and compared to flight instrumentation data from previous flights of the same launch vehicle. This is done to ensure the current mission environments, such as shock, random vibration, and acoustics, are not out of family with existing flight experience. In family means the peaks on the SRS curve for WGS-5 are similar to the peaks from the previous flights and there are no major outliers. The curves from the data will then be compiled into a useful format so that is can be peer reviewed then presented before an engineering review board if required. Also, the reviewed data will be uploaded to the Engineering Review Board Information System (ERBIS) to archive. The second part of this project is conducting Finite Element Analysis of a CubeSat. In 2010, Merritt Island High School partnered with NASA to design, build and launch a CubeSat. The team is now called StangSat in honor of their mascot, the mustang. Over the past few years, the StangSat team has built a satellite and has now been manifested for flight on a SpaceX Falcon 9 launch in 2014. To prepare for the final launch, a test flight was conducted in Mojave, California. StangSat was launched on a Prospector 18D, a high altitude rocket made by Garvey Spacecraft Corporation, along with their sister satellite CP9 built by California Polytechnic University. However, StangSat was damaged during an off nominal landing and this project will give beneficial insights into what loads the CubeSat experienced during the crash
Probabilistic structural analysis for nuclear thermal propulsion
NASA Technical Reports Server (NTRS)
Shah, Ashwin
1993-01-01
Viewgraphs of probabilistic structural analysis for nuclear thermal propulsion are presented. The objective of the study was to develop a methodology to certify Space Nuclear Propulsion System (SNPS) Nozzle with assured reliability. Topics covered include: advantage of probabilistic structural analysis; space nuclear propulsion system nozzle uncertainties in the random variables; SNPS nozzle natural frequency; and sensitivity of primitive variable uncertainties SNPS nozzle natural frequency and shell stress.
Septin crystallization for structural analysis.
Valadares, N F; Garratt, R C
2016-01-01
Septins are filament-forming proteins found in many eukaryotes. Despite being important components of the cytoskeleton, only recently details of their macromolecular assemblies and crystal structures have started to appear in the literature. These are of fundamental importance to the understanding of cytoskeleton dynamics, membrane barrier formation, and bacterial caging, as well as essential cellular processes such as cell division, exocytosis, and vesicle trafficking. However, obtaining this data is frequently hindered by several experimental difficulties common to the majority of septin samples. Here we provide an overview of the current approaches to circumvent or minimize the experimental complications observed in septin crystallography focusing mainly, but not exclusively, on the choice of the septin construct and how to best prepare the sample itself. PMID:27473918
Generalized Structured Component Analysis with Latent Interactions
ERIC Educational Resources Information Center
Hwang, Heungsun; Ho, Moon-Ho Ringo; Lee, Jonathan
2010-01-01
Generalized structured component analysis (GSCA) is a component-based approach to structural equation modeling. In practice, researchers may often be interested in examining the interaction effects of latent variables. However, GSCA has been geared only for the specification and testing of the main effects of variables. Thus, an extension of GSCA…
Structural analysis of second-generation heliostats
Dunder, V.D.
1981-12-01
As part of the overall evaluation of the four second-generation heliostats, a finite element analysis was performed to evaluate structure performance of the mirror modules subjected to gravity, operational wind loads and survival wind loads. All designs evaluated were found to be structurally adequate.
Friction in macroscopic thermodynamics: A kinetic point of view
NASA Astrophysics Data System (ADS)
Bizarro, João P. S.
2015-12-01
To provide a solid support to a macroscopic framework developed to explicitly account for friction in thermodynamics, a kinetic description of frictional dissipation is developed. Using either a dissipative Fokker-Planck equation for Brownian motion or a Boltzmann equation with a friction-force term added, it is shown that both approaches lead to the emergence of the macroscopic thermodynamic relations that state the first and second laws with friction. The analysis is directly applied to the problem of determining the minimum amount of heating generated by memory erasure, known in computer science as Landauer's bound, and leads to a better understanding of the energetics behind the latter. A generalisation of Boltzmann's H theorem to include friction explicitly is also recovered, and the thermodynamics of granular rotators acted by a frictional torque and of radio-frequency (RF) current drive of fusion plasmas, in which collisional drag is present, are addressed as well. Various physics results are revisited employing the first and second laws with friction that have been derived from the appropriate dissipative kinetic equations, lower bounds for entropy production rates being derived both for granular rotators and for RF current drive.
New inroads in an old subject: Plasticity, from around the atomic to the macroscopic scale
NASA Astrophysics Data System (ADS)
Acharya, Amit
2010-05-01
Nonsingular, stressed, dislocation (wall) profiles are shown to be 1-d equilibria of a non-equilibrium theory of Field Dislocation Mechanics (FDM). It is also shown that such equilibrium profiles corresponding to a given level of load cannot generally serve as a travelling wave profile of the governing equation for other values of nearby constant load; however, one case of soft loading with a special form of the dislocation velocity law is demonstrated to have no 'Peierls barrier' in this sense. The analysis is facilitated by the formulation of a 1-d, scalar, time-dependent, Hamilton-Jacobi equation as an exact special case of the full 3-d FDM theory accounting for non-convex elastic energy, small, Nye-tensor-dependent core energy, and possibly an energy contribution based on incompatible slip. Relevant nonlinear stability questions, including that of nucleation, are formulated in a non-equilibrium setting. Elementary averaging ideas show a singular perturbation structure in the evolution of the (unsymmetric) macroscopic plastic distortion, thus pointing to the possibility of predicting generally rate-insensitive slow response constrained to a tensorial 'yield' surface, while allowing fast excursions off it, even though only simple kinetic assumptions are employed in the microscopic FDM theory. The emergent small viscosity on averaging that serves as the small parameter for the perturbation structure is a robust, almost-geometric consequence of large gradients of slip in the dislocation core and the persistent presence of a large number of dislocations in the averaging volume. In the simplest approximation, the macroscopic yield criterion displays anisotropy based on the microscopic dislocation line and Burgers vector distribution, a dependence on the Laplacian of the incompatible slip tensor and a nonlocal term related to a Stokes-Helmholtz-curl projection of an 'internal stress' derived from the incompatible slip energy.
Impact analysis of composite aircraft structures
NASA Technical Reports Server (NTRS)
Pifko, Allan B.; Kushner, Alan S.
1993-01-01
The impact analysis of composite aircraft structures is discussed. Topics discussed include: background remarks on aircraft crashworthiness; comments on modeling strategies for crashworthiness simulation; initial study of simulation of progressive failure of an aircraft component constructed of composite material; and research direction in composite characterization for impact analysis.
Fuzzy Clusterwise Generalized Structured Component Analysis
ERIC Educational Resources Information Center
Hwang, Heungsun; Desarbo, Wayne S.; Takane, Yoshio
2007-01-01
Generalized Structured Component Analysis (GSCA) was recently introduced by Hwang and Takane (2004) as a component-based approach to path analysis with latent variables. The parameters of GSCA are estimated by pooling data across respondents under the implicit assumption that they all come from a single, homogenous group. However, as has been…
Thermal analysis considerations for large space structures
NASA Technical Reports Server (NTRS)
Adelman, H. M.; Shore, C. P.
1983-01-01
A number of issues and needs relative to thermal analysis of large space structures and space stations are discussed. Some indications of trends in the Langley thermal-structural analysis research program consistent with the issues and needs are also presented. The main heat transfer mechanism in space is radiation; consequently, there is a need for a strong thrust on improved radiation analysis capability. Also the important interactions among temperatures, deformations, and controls need to be accounted for. Finite element analysis capability seems to be lagging behind lumped-parameter capability or heat pipe analysis. The Langley plan will include improving radiation analysis capability, evaluating the errors involved in certain approximate analysis and modeling techniques for large space trusses, and continuing the development of integrated thermal-structural finite elements with an emphasis on radiation heat transfer. Work will be initiated to develop finite element analysis techniques for heat pipes. Finally, optimization research activities will be oriented toward methods to design flexible orbiting structures to account for thermal and thermal deformation requirements.
Structural Analysis in a Conceptual Design Framework
NASA Technical Reports Server (NTRS)
Padula, Sharon L.; Robinson, Jay H.; Eldred, Lloyd B.
2012-01-01
Supersonic aircraft designers must shape the outer mold line of the aircraft to improve multiple objectives, such as mission performance, cruise efficiency, and sonic-boom signatures. Conceptual designers have demonstrated an ability to assess these objectives for a large number of candidate designs. Other critical objectives and constraints, such as weight, fuel volume, aeroelastic effects, and structural soundness, are more difficult to address during the conceptual design process. The present research adds both static structural analysis and sizing to an existing conceptual design framework. The ultimate goal is to include structural analysis in the multidisciplinary optimization of a supersonic aircraft. Progress towards that goal is discussed and demonstrated.
Structural response analysis of tension leg platforms
Yoshida, K.; Oka, N.; Ozaki, M.
1984-03-01
A linear response analysis method of the Tension Leg Platform (TLP) subjected to regular waves is proposed. In this analysis method, flexibility of the superstructure can be taken into account in the equations of motion; response motions, tension variations of tendons and structural member forces are solved simultaneously. The applicability of this method is confirmed by comparison with the test results on two kinds of small-scale TLP models. The structural responses obtained from these calculations and their effects on tension variation of tendons are studied. Finally, several kinds of structural response characteristics are conclusively discussed.
Seismic analysis of nuclear power plant structures
NASA Technical Reports Server (NTRS)
Go, J. C.
1973-01-01
Primary structures for nuclear power plants are designed to resist expected earthquakes of the site. Two intensities are referred to as Operating Basis Earthquake and Design Basis Earthquake. These structures are required to accommodate these seismic loadings without loss of their functional integrity. Thus, no plastic yield is allowed. The application of NASTRAN in analyzing some of these seismic induced structural dynamic problems is described. NASTRAN, with some modifications, can be used to analyze most structures that are subjected to seismic loads. A brief review of the formulation of seismic-induced structural dynamics is also presented. Two typical structural problems were selected to illustrate the application of the various methods of seismic structural analysis by the NASTRAN system.
Structural-Thermal-Optical-Performance (STOP) Analysis
NASA Technical Reports Server (NTRS)
Bolognese, Jeffrey; Irish, Sandra
2015-01-01
The presentation will be given at the 26th Annual Thermal Fluids Analysis Workshop (TFAWS 2015) hosted by the Goddard Spaceflight Center (GSFC) Thermal Engineering Branch (Code 545). A STOP analysis is a multidiscipline analysis, consisting of Structural, Thermal and Optical Performance Analyses, that is performed for all space flight instruments and satellites. This course will explain the different parts of performing this analysis. The student will learn how to effectively interact with each discipline in order to accurately obtain the system analysis results.
Thermal and structural analysis of Hermes
NASA Astrophysics Data System (ADS)
Petiau, C.
1989-01-01
The organization of the thermal and structural analysis of the Hermes project is described. A way to resolve the problem of connections between calculations performed by the different Hermes partners is outlined. The interactions between the general model of TPS (thermal protection system) used for global dimensioning of insulation, and refined thermal models giving accurate temperature map details of hot and cold structures, are described. The organization of the structural analysis is based on a finite element general model which supports preliminary design, loads and vibration analyses. Boundary conditions for refined subpart analyses, are cut to size, into the general model by super element techniques. This process involves the use by all partners of efficient computer codes. The Catia-Elfini software system is proposed as a possible code system for structural analysis and optimization purposes.
Simultaneous analysis and design. [in structural engineering
NASA Technical Reports Server (NTRS)
Haftka, R. T.
1985-01-01
Optimization techniques are increasingly being used for performing nonlinear structural analysis. The development of element by element (EBE) preconditioned conjugate gradient (CG) techniques is expected to extend this trend to linear analysis. Under these circumstances the structural design problem can be viewed as a nested optimization problem. There are computational benefits to treating this nested problem as a large single optimization problem. The response variables (such as displacements) and the structural parameters are all treated as design variables in a unified formulation which performs simultaneously the design and analysis. Two examples are used for demonstration. A seventy-two bar truss is optimized subject to linear stress constraints and a wing box structure is optimized subject to nonlinear collapse constraints. Both examples show substantial computational savings with the unified approach as compared to the traditional nested approach.
Thermal analysis of the TMT telescope structure
NASA Astrophysics Data System (ADS)
Cho, Myung; Corredor, Andrew; Vogiatzis, Konstantinos; Angeli, George
2010-07-01
Thermal performances of the Thirty Meter Telescope (TMT) structure were evaluated by finite element thermal models. The thermal models consist of the telescope optical assembly systems, instruments, laser facility, control and electronic equipments, and structural members. Temporal and spatial temperature distributions of the optical assembly systems and the telescope structure were calculated under various thermal conditions including air convections, conductions, heat flux loadings, and radiations. In order to capture thermal responses faithfully, a three-consecutive-day thermal environment data was implemented. This thermal boundary condition was created by CFD based on the environment conditions of the corresponding TMT site. The thermo-elastic analysis was made to predict thermal deformations of the telescope structure at every hour for three days. The line of sight calculation was made using the thermally induced structural deformations. Merit function was utilized to calculate the OPD maps after repositioning the optics based on a best fit of M1 segment deformations. The goal of this thermal analysis is to establish creditable thermal models by finite element analysis to simulate the thermal effects with the TMT site environment data. These thermal models can be utilized for estimating the thermal responses of the TMT structure. Thermal performance prediction of the TMT structure will guide us to assess the thermal impacts, and enables us to establish a thermal control strategy and requirements in order to minimize the thermal effects on the telescope structure due to heat dissipation from the telescope mounted equipment and systems.
Probabilistic structural analysis computer code (NESSUS)
NASA Technical Reports Server (NTRS)
Shiao, Michael C.
1988-01-01
Probabilistic structural analysis has been developed to analyze the effects of fluctuating loads, variable material properties, and uncertain analytical models especially for high performance structures such as SSME turbopump blades. The computer code NESSUS (Numerical Evaluation of Stochastic Structure Under Stress) was developed to serve as a primary computation tool for the characterization of the probabilistic structural response due to the stochastic environments by statistical description. The code consists of three major modules NESSUS/PRE, NESSUS/FEM, and NESSUS/FPI. NESSUS/PRE is a preprocessor which decomposes the spatially correlated random variables into a set of uncorrelated random variables using a modal analysis method. NESSUS/FEM is a finite element module which provides structural sensitivities to all the random variables considered. NESSUS/FPI is Fast Probability Integration method by which a cumulative distribution function or a probability density function is calculated.
Macroscopic definition of distributed swarm morphogenesis
NASA Astrophysics Data System (ADS)
Aznar, Fidel; Pujol, Mar; Rizo, Ramón
2012-12-01
In this paper, we present a system that will be able to obtain microscopic assembly behaviours for a robotic swarm to achieve an assembly target (macroscopic model). It will be designed taking into consideration the essential features of a self-assembling system needed to be implemented in a real robotic swarm. This system is composed of a typology of generative languages PD0L, and an algorithm for generating individual rules to be processed by the robots. The assembly process will be performed in a distributed manner, and will be also designed to require minimal communication capabilities between robots. Both the expressive capacities of language and the rule generation algorithm will be demonstrated by evaluating their performance with a core set of test morphologies widely used in self-assembly tasks. Furthermore, we compare the assembly time and the number of messages required between a classic controller (centralised) and our distributed approach.
Macroscopic balance model for wave rotors
NASA Technical Reports Server (NTRS)
Welch, Gerard E.
1996-01-01
A mathematical model for multi-port wave rotors is described. The wave processes that effect energy exchange within the rotor passage are modeled using one-dimensional gas dynamics. Macroscopic mass and energy balances relate volume-averaged thermodynamic properties in the rotor passage control volume to the mass, momentum, and energy fluxes at the ports. Loss models account for entropy production in boundary layers and in separating flows caused by blade-blockage, incidence, and gradual opening and closing of rotor passages. The mathematical model provides a basis for predicting design-point wave rotor performance, port timing, and machine size. Model predictions are evaluated through comparisons with CFD calculations and three-port wave rotor experimental data. A four-port wave rotor design example is provided to demonstrate model applicability. The modeling approach is amenable to wave rotor optimization studies and rapid assessment of the trade-offs associated with integrating wave rotors into gas turbine engine systems.
Macroscopically local correlations can violate information causality.
Cavalcanti, Daniel; Salles, Alejo; Scarani, Valerio
2010-01-01
Although quantum mechanics is a very successful theory, its foundations are still a subject of intense debate. One of the main problems is that quantum mechanics is based on abstract mathematical axioms, rather than on physical principles. Quantum information theory has recently provided new ideas from which one could obtain physical axioms constraining the resulting statistics one can obtain in experiments. Information causality (IC) and macroscopic locality (ML) are two principles recently proposed to solve this problem. However, none of them were proven to define the set of correlations one can observe. In this study, we show an extension of IC and study its consequences. It is shown that the two above-mentioned principles are inequivalent: if the correlations allowed by nature were the ones satisfying ML, IC would be violated. This gives more confidence in IC as a physical principle, defining the possible correlation allowed by nature. PMID:21266986
Macroscopic model of scanning force microscope
Guerra-Vela, Claudio; Zypman, Fredy R.
2004-10-05
A macroscopic version of the Scanning Force Microscope is described. It consists of a cantilever under the influence of external forces, which mimic the tip-sample interactions. The use of this piece of equipment is threefold. First, it serves as direct way to understand the parts and functions of the Scanning Force Microscope, and thus it is effectively used as an instructional tool. Second, due to its large size, it allows for simple measurements of applied forces and parameters that define the state of motion of the system. This information, in turn, serves to compare the interaction forces with the reconstructed ones, which cannot be done directly with the standard microscopic set up. Third, it provides a kinematics method to non-destructively measure elastic constants of materials, such as Young's and shear modules, with special application for brittle materials.
Taming macroscopic jamming in transportation networks
NASA Astrophysics Data System (ADS)
Ezaki, Takahiro; Nishi, Ryosuke; Nishinari, Katsuhiro
2015-06-01
In transportation networks, a spontaneous jamming transition is often observed, e.g. in urban road networks and airport networks. Because of this instability, flow distribution is significantly imbalanced on a macroscopic level. To mitigate the congestion, we consider a simple control method, in which congested nodes are closed temporarily, and investigate how it influences the overall system. Depending on the timing of the node closure and opening, and congestion level of a network, the system displays three different phases: free-flow phase, controlled phase, and deadlock phase. We show that when the system is in the controlled phase, the average flow is significantly improved, whereas when in the deadlock phase, the flow drops to zero. We study how the control method increases the network flow and obtain their transition boundary analytically.
Macroscopic and direct light propulsion of bulk graphene material
NASA Astrophysics Data System (ADS)
Zhang, Tengfei; Chang, Huicong; Wu, Yingpeng; Xiao, Peishuang; Yi, Ningbo; Lu, Yanhong; Ma, Yanfeng; Huang, Yi; Zhao, Kai; Yan, Xiao-Qing; Liu, Zhi-Bo; Tian, Jian-Guo; Chen, Yongsheng
2015-07-01
It has been a great challenge to achieve the direct light manipulation of matter on a bulk scale. In this work the direct light propulsion of matter is observed on a macroscopic scale using a bulk graphene-based material. The unique structure and properties of graphene, and the novel morphology of the bulk three-dimensional linked graphene material make it capable not only of absorbing light at various wavelengths but also of emitting energetic electrons efficiently enough to drive the bulk material, following Newtonian mechanics. Thus, the unique photonic and electronic properties of individual graphene sheets are manifested in the response of the bulk state. These results offer an exciting opportunity to bring about bulk-scale light manipulation with the potential to realize long-sought applications in areas such as the solar sail and space transportation driven directly by sunlight.
Macroscopic chirality of a liquid crystal from nonchiral molecules
Jakli, A.; Nair, G. G.; Lee, C. K.; Sun, R.; Chien, L. C.
2001-06-01
The transfer of chirality from nonchiral polymer networks to the racemic B2 phase of nonchiral banana-shaped molecules is demonstrated. This corresponds to the transfer of chirality from an achiral material to another achiral material. There are two levels of chirality transfers. (a) On a microscopic level the presence of a polymer network (chiral or nonchiral) favors a chiral state over a thermodynamically stable racemic state due to the inversion symmetry breaking at the polymer-liquid crystal interfaces. (b) A macroscopically chiral (enantimerically enriched) sample can be produced if the polymer network has a helical structure, and/or contains chemically chiral groups. The chirality transfer can be locally suppressed by exposing the liquid crystal to a strong electric field treatment.
NASA Technical Reports Server (NTRS)
Johnson, Adriel D.
1992-01-01
Conditions simulating low- and high-gravity, reveal changes in macroscopic pattern formation in selected microorganisms, but whether these structures are gravity dependent is not clear. Two theories have been identified in the fluid dynamics community which support macroscopic pattern formation. The first one is gravity dependent (fluid density models) where small concentrated regions of organisms sink unstably, and the second is gravity independent (wave reinforcement theory) where organisms align their movements in concert, such that either their swimming strokes beat in phase or their vortices entrain neighbors to follow parallel paths. Studies have shown that macroscopic pattern formation is consistent with the fluid density models for protozoa and algae and wave reinforcement hypothesis for caprine spermatozoa.
NASA Technical Reports Server (NTRS)
Saether, Erik; Hochhalter, Jacob D.; Glaessgen, Edward H.; Mishin, Yuri
2014-01-01
A multiscale modeling methodology is developed for structurally-graded material microstructures. Molecular dynamic (MD) simulations are performed at the nanoscale to determine fundamental failure mechanisms and quantify material constitutive parameters. These parameters are used to calibrate material processes at the mesoscale using discrete dislocation dynamics (DD). Different grain boundary interactions with dislocations are analyzed using DD to predict grain-size dependent stress-strain behavior. These relationships are mapped into crystal plasticity (CP) parameters to develop a computationally efficient finite element-based DD/CP model for continuum-level simulations and complete the multiscale analysis by predicting the behavior of macroscopic physical specimens. The present analysis is focused on simulating the behavior of a graded microstructure in which grain sizes are on the order of nanometers in the exterior region and transition to larger, multi-micron size in the interior domain. This microstructural configuration has been shown to offer improved mechanical properties over homogeneous coarse-grained materials by increasing yield stress while maintaining ductility. Various mesoscopic polycrystal models of structurally-graded microstructures are generated, analyzed and used as a benchmark for comparison between multiscale DD/CP model and DD predictions. A final series of simulations utilize the DD/CP analysis method exclusively to study macroscopic models that cannot be analyzed by MD or DD methods alone due to the model size.
Macroscopic entanglement in many-particle quantum states
NASA Astrophysics Data System (ADS)
Tichy, Malte C.; Park, Chae-Yeun; Kang, Minsu; Jeong, Hyunseok; Mølmer, Klaus
2016-04-01
We elucidate the relationship between Schrödinger-cat-like macroscopicity and geometric entanglement and argue that these quantities are not interchangeable. While both properties are lost due to decoherence, we show that macroscopicity is rare in uniform and in so-called random physical ensembles of pure quantum states, despite possibly large geometric entanglement. In contrast, permutation-symmetric pure states feature rather low geometric entanglement and strong and robust macroscopicity.
Gonzalez, Lee; Wade, Matthew; Bell, Nancy; Thomas, Kate; Wess, Tim
2013-02-01
Maintaining appropriate temperatures and relative humidity is considered essential to extending the useful life of parchment artifacts. Although the relationship between environmental factors and changes to the physical state of artifacts is reasonably understood, an improved understanding of the relationship between the molecular conformation and changes to the macroscopic condition of parchment is needed to optimize environmental conditions. Using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR FT-IR) analysis, the conformation of the molecular structure in selected parchment samples with specific macroscopic conditions, typically discoloration and planar deformations (e.g., cockling and tearing), have been made. The results of this investigation showed that the Fourier transform infrared signal differs for parchment samples exhibiting different macroscopic conditions. In areas exhibiting planar deformation, a change in the Fourier Transform Infrared signal was observed that indicates unfolding of the molecular conformation. In comparison, the discolored samples showed a change in molecular conformation that indicates a chemical change within the collagen molecular structure. This paper discusses the possible causal associations and implications of these findings for the conservation and preservation of parchment artifacts.
Analysis and sizing of Mars aerobrake structure
NASA Technical Reports Server (NTRS)
Raju, I. S.; Craft, W. J.
1993-01-01
A cone-sphere aeroshell structure for aerobraking into Martian atmosphere is studied. Using this structural configuration, a space frame load-bearing structure is proposed. To generate this structure efficiently and to perform a variety of studies of several configurations, a mesh generator that utilizes only a few configurational parameters is developed. A finite element analysis program that analyzes space frame structures was developed. A sizing algorithm that arrives at a minimum mass configuration was developed and integrated into the finite element analysis program. A typical 135-ft-diam aerobrake configuration was analyzed and sized. The minimum mass obtained in this study using high modulus graphite/epoxy composite material members is compared with the masses obtained from two other aerobrake structures using lightweight erectable tetrahedral truss and part-spherical truss configurations. Excellent agreement for the minimum mass was obtained with the three different aerobrake structures. Also, the minimum mass using the present structure was obtained when the supports were not at the base but at about 75 percent of the base diameter.
Analysis of flexible structures under lateral impact
Ramirez, D. F.; Razavi, H.
2012-07-01
Three methods for analysis of flexible structures under lateral impact are presented. The first proposed method (Method A) consists of: (1) modifying an available deceleration on a rigid target with conservation principles to account for structural flexibility; and (2) transient nonlinear analysis of the structure with the corrected forcing function. The second proposed method (Method B) is similar to Method A in obtaining the forcing function but it solves the equations of motion of an idealized two-degree-of-freedom system instead of directly using conservation principles. The last method simply provides the maximum force in the structure using the conservation of energy and linear momentum. A coupled simulation is also performed in LS-DYNA and compared against the proposed methods. A case study is presented to illustrate the applicability of all three methods and the LS-DYNA simulation. (authors)
Toroidal dipolar excitation and macroscopic electromagnetic properties of metamaterials
NASA Astrophysics Data System (ADS)
Savinov, V.; Fedotov, V. A.; Zheludev, N. I.
2014-05-01
The toroidal dipole is a peculiar electromagnetic excitation that can not be presented in terms of standard electric and magnetic multipoles. A static toroidal dipole has been shown to lead to violation of parity in atomic spectra and many other unusual electromagnetic phenomena. The existence of electromagnetic resonances of toroidal nature was experimentally demonstrated only recently, first in the microwave metamaterials, and then at optical frequencies, where they could be important in spectroscopy analysis of a wide class of media with constituents of toroidal symmetry, such as complex organic molecules, fullerenes, bacteriophages, etc. Despite the experimental progress in studying toroidal resonances, no direct link has yet been established between microscopic toroidal excitations and macroscopic scattering characteristics of the medium. To address this essential gap in the electromagnetic theory, we have developed an analytical approach for calculating the transmissivity and reflectivity of thin slabs of materials that exhibit toroidal dipolar excitations.
Structural analysis for a 40-story building
NASA Technical Reports Server (NTRS)
Hua, L.
1972-01-01
NASTRAN was chosen as the principal analytical tool for structural analysis of the Illinois Center Plaza Hotel Building in Chicago, Illinois. The building is a 40-story, reinforced concrete structure utilizing a monolithic slab-column system. The displacements, member stresses, and foundation loads due to wind load, live load, and dead load were obtained through a series of NASTRAN runs. These analyses and the input technique are described.
Structural sensitivity analysis: Methods, applications and needs
NASA Technical Reports Server (NTRS)
Adelman, H. M.; Haftka, R. T.; Camarda, C. J.; Walsh, J. L.
1984-01-01
Innovative techniques applicable to sensitivity analysis of discretized structural systems are reviewed. The techniques include a finite difference step size selection algorithm, a method for derivatives of iterative solutions, a Green's function technique for derivatives of transient response, simultaneous calculation of temperatures and their derivatives, derivatives with respect to shape, and derivatives of optimum designs with respect to problem parameters. Computerized implementations of sensitivity analysis and applications of sensitivity derivatives are also discussed. Some of the critical needs in the structural sensitivity area are indicated along with plans for dealing with some of those needs.
Structural sensitivity analysis: Methods, applications, and needs
NASA Technical Reports Server (NTRS)
Adelman, H. M.; Haftka, R. T.; Camarda, C. J.; Walsh, J. L.
1984-01-01
Some innovative techniques applicable to sensitivity analysis of discretized structural systems are reviewed. These techniques include a finite-difference step-size selection algorithm, a method for derivatives of iterative solutions, a Green's function technique for derivatives of transient response, a simultaneous calculation of temperatures and their derivatives, derivatives with respect to shape, and derivatives of optimum designs with respect to problem parameters. Computerized implementations of sensitivity analysis and applications of sensitivity derivatives are also discussed. Finally, some of the critical needs in the structural sensitivity area are indicated along with Langley plans for dealing with some of these needs.
RNA Secondary Structure Analysis Using RNAstructure.
Mathews, David H
2014-06-17
RNAstructure is a user-friendly program for the prediction and analysis of RNA secondary structure. It is available as a Web server, as a program with a graphical user interface, or as a set of command-line tools. The programs are available for Microsoft Windows, Macintosh OS X, or Linux. This unit provides protocols for RNA secondary structure prediction (using the Web server or the graphical user interface) and prediction of high-affinity oligonucleotide biding sites to a structured RNA target (using the graphical user interface).
Improving transient analysis technology for aircraft structures
NASA Technical Reports Server (NTRS)
Melosh, R. J.; Chargin, Mladen
1989-01-01
Aircraft dynamic analyses are demanding of computer simulation capabilities. The modeling complexities of semi-monocoque construction, irregular geometry, high-performance materials, and high-accuracy analysis are present. At issue are the safety of the passengers and the integrity of the structure for a wide variety of flight-operating and emergency conditions. The technology which supports engineering of aircraft structures using computer simulation is examined. Available computer support is briefly described and improvement of accuracy and efficiency are recommended. Improved accuracy of simulation will lead to a more economical structure. Improved efficiency will result in lowering development time and expense.
ERIC Educational Resources Information Center
Cook, Michelle; Wiebe, Eric N.; Carter, Glenda
2008-01-01
Previous research has indicated that the use of multiple representations with macroscopic and molecular features can improve conceptual understanding; however, the influence of prior knowledge of the domain cannot be overlooked. Using eye-tracking technology and sequential analysis, this study investigated how high school students (n = 54) with…
The Assessment of Structural Analysis Skills.
ERIC Educational Resources Information Center
Johnson, Dale D.; And Others
Two studies were undertaken to continue a line of research designed to identify the subskills of word identification that correlate most highly with reading comprehension and to develop empirically based instruments to assess those subskills. The issues studied related to the broad area of structural analysis and concerned assessment of skills in…
Cloud Macroscopic Organization: Order Emerging from Randomness
NASA Technical Reports Server (NTRS)
Yuan, Tianle
2011-01-01
Clouds play a central role in many aspects of the climate system and their forms and shapes are remarkably diverse. Appropriate representation of clouds in climate models is a major challenge because cloud processes span at least eight orders of magnitude in spatial scales. Here we show that there exists order in cloud size distribution of low-level clouds, and that it follows a power-law distribution with exponent gamma close to 2. gamma is insensitive to yearly variations in environmental conditions, but has regional variations and land-ocean contrasts. More importantly, we demonstrate this self-organizing behavior of clouds emerges naturally from a complex network model with simple, physical organizing principles: random clumping and merging. We also demonstrate symmetry between clear and cloudy skies in terms of macroscopic organization because of similar fundamental underlying organizing principles. The order in the apparently complex cloud-clear field thus has its root in random local interactions. Studying cloud organization with complex network models is an attractive new approach that has wide applications in climate science. We also propose a concept of cloud statistic mechanics approach. This approach is fully complementary to deterministic models, and the two approaches provide a powerful framework to meet the challenge of representing clouds in our climate models when working in tandem.
Macroscopic hematuria in patients on anticoagulation therapy
Mariyanovski, Valeri; Hadzhiyska, Valeria
2015-01-01
Introduction Visible hematuria is not rare in patients on anticoagulant therapy. There is no consensus regarding the diagnostic approach for them; some authors suggest restricted volume of diagnostic procedures because of the low number of urological etiology found. Some antibiotics have been reported to potentiate the effect of oral anticoagulants. Material and methods The study addresses the need for urological assessment of patients on anticoagulation therapy and the possible role of some drugs administrated simultaneously with an oral anticoagulant, for the onset of macroscopic hematuria. Patients hospitalized with hematuria, both with or without anticoagulation therapy, were investigated and followed up. Results The onset of hematuria depends on the monitoring of oral anticoagulation. INR (International Normalized Ratio) value corresponds with the probability of non-urological etiology, where INR>4 carries relatively low risk for urological and malignant etiology. Some antibiotics may influence the anticoagulation effect, so INR value may be elevated and hematuria may occur. Conclusions Anticoagulation therapy should be administrated carefully and individually. The risk of urological etiology of hematuria is lower in patients on oral anticoagulants (especially when INR >4), however, it is not zero. PMID:26568876
Macroscopic characteristics of the praying mantis electroretinogram.
Popkiewicz, Barbara; Prete, Frederick R
2013-08-01
We described the macroscopic characteristics of the praying mantis ERG in three species, Tenodera aridifolia sinensis, Sphodromantis lineola, and Popa spurca. In all cases, when elicited by square wave light pulses longer than 400 ms, light adapted (LA) ERGs consisted of four component waveforms: a cornea negative transient and sustained ON, a cornea negative transient OFF, and a cornea positive sustained OFF. The former two ON, and the latter OFF components were attributed to photoreceptor depolarization and repolarization, respectively. Metabolic stress via CO2 induced anoxia selectively eliminated the transient OFF (independent of its effect on the other components) suggesting the transient OFF represents activity of the lamina interneurons on which the photoreceptors synapse. Dark adapted (DA) ERGs differed from LA ERGs in that the sustained ON and OFF amplitudes were larger, and the transient ON and OFF components were absent. Increased stimulus durations increased the amplitudes and derivatives of, and decreased the latencies to the maximum amplitudes of the OFF components. Increasing stimulus intensity increased the amplitude of the sustained ON and OFF components, but not the transient OFF. These results suggest that the mantis' visual system displays increased contrast coding efficiency with increased light adaptation, and that there are differences in gain between photoreceptor and lamina interneuron responses. Finally, responses to luminance decrements as brief a 1 ms were evident in LA recordings, and were resolved at frequencies up to 60 Hz. PMID:23684801
Macroscopic resonant tunnelling through Andreev interferometers
NASA Astrophysics Data System (ADS)
Goorden, M. C.; Jacquod, Ph; Weiss, J.
2008-04-01
We investigate the conductance through and the spectrum of ballistic chaotic quantum dots attached to two s-wave superconductors, as a function of the phase difference phi between the two order parameters. A combination of analytical techniques—random matrix theory, Nazarov's circuit theory and the trajectory-based semiclassical theory—allows us to explore the quantum-to-classical crossover in detail. When the superconductors are not phase-biased, phi = 0, we recover known results that the spectrum of the quantum dot exhibits an excitation gap, while the conductance across two normal leads carrying NN channels and connected to the dot via tunnel contacts of transparency ΓN is \\propto \\Gamma_{\\mathrm {N}}^2 N_{\\mathrm {N}} . In contrast, when phi = π, the excitation gap closes and the conductance becomes G \\propto \\Gamma_{\\mathrm {N}} N_{\\mathrm {N}} in the universal regime. For \\Gamma_{\\mathrm {N}} \\ll 1 , we observe an order-of-magnitude enhancement of the conductance towards G \\propto N_{\\mathrm {N}} in the short-wavelength limit. We relate this enhancement to resonant tunnelling through a macroscopic number of levels close to the Fermi energy. Our predictions are corroborated by numerical simulations.
Macroscopic resonant tunnelling through Andreev interferometers.
Goorden, M C; Jacquod, Ph; Weiss, J
2008-04-01
We investigate the conductance through and the spectrum of ballistic chaotic quantum dots attached to two s-wave superconductors, as a function of the phase difference phi between the two order parameters. A combination of analytical techniques-random matrix theory, Nazarov's circuit theory and the trajectory-based semiclassical theory-allows us to explore the quantum-to-classical crossover in detail. When the superconductors are not phase-biased, phi = 0, we recover known results that the spectrum of the quantum dot exhibits an excitation gap, while the conductance across two normal leads carrying N(N) channels and connected to the dot via tunnel contacts of transparency Gamma(N) is [Formula: see text]. In contrast, when phi = pi, the excitation gap closes and the conductance becomes [Formula: see text] in the universal regime. For [Formula: see text], we observe an order-of-magnitude enhancement of the conductance towards [Formula: see text] in the short-wavelength limit. We relate this enhancement to resonant tunnelling through a macroscopic number of levels close to the Fermi energy. Our predictions are corroborated by numerical simulations. PMID:19636148
Investigation of dissipative forces near macroscopic media
Becker, R.S.
1982-12-01
The interaction of classical charged particles with the fields they induce in macroscopic dielectric media is investigated. For 10- to 1000-eV electrons, the angular perturbation of the trajectory by the image potential for surface impact parameters of 50 to 100 A is shown to be of the order of 0.001 rads over a distance of 100 A. The energy loss incurred by low-energy particles due to collective excitations such as surface plasmons is shown to be observable with a transition probability of 0.01 to 0.001 (Becker, et al., 1981b). The dispersion of real surface plasmon modes in planar and cylindrical geometries is discussed and is derived for pinhole geometry described in terms of a single-sheeted hyperboloid of revolution. An experimental apparatus for the measurement of collective losses for medium-energy electrons translating close to a dielectric surface is described and discussed. Data showing such losses at electron energies of 500 to 900 eV in silver foils containing many small apertures are presented and shown to be in good agreement with classical stopping power calculations and quantum mechanical calculations carried out in the low-velocity limit. The data and calculations are compared and contrasted with earlier transmission and reflection measurements, and the course of further investigation is discussed.
Turbine blade nonlinear structural and life analysis
NASA Technical Reports Server (NTRS)
Mcknight, R. L.; Laflen, J. H.; Halford, G. R.; Kaufman, A.
1982-01-01
The utility of advanced structural analysis and life prediction techniques was evaluated for the life assessment of a commercial air-cooled turbine blade with a history of tip cracking. Three dimensional, nonlinear finite element structural analyses were performed for the blade tip region. The computed strain-temperature history of the critical location was imposed on a uniaxial strain controlled test specimen to evaluate the validity of the structural analysis method. Experimental results indicated higher peak stresses and greater stress relaxation than the analytical predictions. Life predictions using the Strainrange Partitioning and Frequency Modified approaches predicted 1200 to 4420 cycles and 2700 cycles to crack initiation, respectively, compared to an observed life of 3000 cycles.
Macroscopic quantum tunnelling in a current biased Josephson junction
Martinis, J.M.; Devoret, M.H.; Clarke, J.; Urbina, C.
1984-11-01
We discuss in this work an attempt to answer experimentally the question: do macroscopic variables obey quantum mechanics. More precisely, this experiment deals with the question of quantum-mechanical tunnelling of a macroscopic variable, a subject related to the famous Schrodinger's cat problem in the theory of measurement.
Shape analysis of simulated breast anatomical structures
NASA Astrophysics Data System (ADS)
Contijoch, Francisco; Lynch, Jennifer M.; Pokrajac, David D.; Maidment, Andrew D. A.; Bakic, Predrag R.
2012-03-01
Recent advances in high-resolution 3D breast imaging, namely, digital breast tomosynthesis and dedicated breast CT, have enabled detailed analysis of the shape and distribution of anatomical structures in the breast. Such analysis is critically important, since the projections of breast anatomical structures make up the parenchymal pattern in clinical images which can mask the existing abnormalities or introduce false alarms; the parenchymal pattern is also correlated with the risk of cancer. As a first step towards the shape analysis of anatomical structures in the breast, we have analyzed an anthropomorphic software breast phantom. The phantom generation is based upon the recursive splitting of the phantom volume using octrees, which produces irregularly shaped tissue compartments, qualitatively mimicking the breast anatomy. The shape analysis was performed by fitting ellipsoids to the simulated tissue compartments. The ellipsoidal semi-axes were calculated by matching the moments of inertia of each individual compartment and of an ellipsoid. The distribution of Dice coefficients, measuring volumetric overlap between the compartment and the corresponding ellipsoid, as well as the distribution of aspect ratios, measuring relative orientations of the ellipsoids, were used to characterize various classes of phantoms with qualitatively distinctive appearance. A comparison between input parameters for phantom generation and the properties of fitted ellipsoids indicated the high level of user control in the design of software breast phantoms. The proposed shape analysis could be extended to clinical breast images, and used to inform the selection of simulation parameters for improved realism.
Functional network macroscopes for probing past and present Earth system dynamics (Invited)
NASA Astrophysics Data System (ADS)
Donges, J. F.
2013-12-01
The Earth, as viewed from a physicist's perspective, is a dynamical system of great complexity. Functional complex networks are inferred from observational data and model runs or constructed on the basis of theoretical considerations. Representing statistical interdependencies or causal interactions between objects (e.g., Earth system subdomains, processes, or local field variables), functional complex networks are conceptually well-suited for naturally addressing some of the fundamental questions of Earth system analysis concerning, among others, major dynamical patterns, teleconnections, and feedback loops in the planetary machinery, as well as critical elements such as thresholds, bottlenecks, and switches. The first part of this talk concerns complex network theory and network-based time series analysis. Regarding complex network theory, the novel contributions include consistent frameworks for analyzing the topology of (i) general networks of interacting networks and (ii) networks with vertices of heterogeneously distributed weights, as well as (iii) an analytical theory for describing spatial networks. In the realm of time series analysis, (i) recurrence network analysis is put forward as a theoretically founded, nonlinear technique for the study of single, but possibly multivariate time series. (ii) Coupled climate networks are introduced as an exploratory tool of data analysis for quantitatively characterizing the intricate statistical interdependency structure within and between several fields of time series. The second part presents applications for detecting dynamical transitions (tipping points) in time series and studying bottlenecks in the atmosphere's general circulation structure. The analysis of paleoclimate data reveals a possible influence of large-scale shifts in Plio-Pleistocene African climate variability on events in human evolution. This presentation summarizes the contents of the dissertation titled "Functional network macroscopes for
Economic Evaluation of Computerized Structural Analysis
NASA Technical Reports Server (NTRS)
Fortin, P. E.
1985-01-01
This completed effort involved a technical and economic study of the capabilities of computer programs in the area of structural analysis. The applicability of the programs to NASA projects and to other users was studied. The applications in other industries was explored including both research and development and applied areas. The costs of several alternative analysis programs were compared. A literature search covered applicable technical literature including journals, trade publications and books. In addition to the literature search, several commercial companies that have developed computerized structural analysis programs were contacted and their technical brochures reviewed. These programs include SDRC I-DEAS, MSC/NASTRAN, SCADA, SUPERSAP, NISA/DISPLAY, STAAD-III, MICAS, GTSTRUDL, and STARS. These programs were briefly reviewed as applicable to NASA projects.
Out of plane analysis for composite structures
NASA Technical Reports Server (NTRS)
Paul, P. C.; Saff, C. R.; Sanger, Kenneth B.; Mahler, M. A.; Kan, Han Pin; Kautz, Edward F.
1990-01-01
Simple two dimensional analysis techniques were developed to aid in the design of strong joints for integrally stiffened/bonded composite structures subjected to out of plane loads. It was found that most out of plane failures were due to induced stresses arising from rapid changes in load path direction or geometry, induced stresses due to changes in geometry caused by buckling, or direct stresses produced by fuel pressure or bearing loads. While the analysis techniques were developed to address a great variety of out of plane loading conditions, they were primarily derived to address the conditions described above. The methods were developed and verified using existing element test data. The methods were demonstrated using the data from a test failure of a high strain wingbox that was designed, built, and tested under a previous program. Subsequently, a set of design guidelines were assembled to assist in the design of safe, strong integral composite structures using the analysis techniques developed.
Macroscopic modeling of plant water uptake: soil and root resistances
NASA Astrophysics Data System (ADS)
Vogel, Tomas; Votrubova, Jana; Dohnal, Michal; Dusek, Jaromir
2014-05-01
The macroscopic physically-based plant root water uptake (RWU) model, based on water-potential-gradient formulation (Vogel et al., 2013), was used to simulate the observed soil-plant-atmosphere interactions at a forest site located in a temperate humid climate of central Europe and to gain an improved insight into the mutual interplay of RWU parameters that affects the soil water distribution in the root zone. In the applied RWU model, the uptake rates are directly proportional to the potential gradient and indirectly proportional to the local soil and root resistances to water flow. The RWU algorithm is implemented in a one-dimensional dual-continuum model of soil water flow based on Richards' equation. The RWU model is defined by four parameters (root length density distribution, average active root radius, radial root resistance, and the threshold value of the root xylem potential). In addition, soil resistance to water extraction by roots is related to soil hydraulic conductivity function and actual soil water content. The RWU model is capable of simulating both the compensatory root water uptake, in situations when reduced uptake from dry layers is compensated by increased uptake from wetter layers, and the root-mediated hydraulic redistribution of soil water, contributing to more natural soil moisture distribution throughout the root zone. The present study focusses on the sensitivity analysis of the combined soil water flow and RWU model responses in respect to variations of RWU model parameters. Vogel T., M. Dohnal, J. Dusek, J. Votrubova, and M. Tesar. 2013. Macroscopic modeling of plant water uptake in a forest stand involving root-mediated soil-water redistribution. Vadose Zone Journal, 12, 10.2136/vzj2012.0154.
Akram, Raheel; Cheng, Mengjiao; Guo, Fengli; Iqbal, Saleem; Shi, Feng
2016-04-19
The mismatching phenomena are ubiquitous in complex and advanced self-assembly, such as hierarchical assembly, macroscopic supramolecular assembly, and so on. Recently, for macroscopic supramolecular assembly, the strategy of maximizing the interactive surface area was used and supposed to handle this problem; however, now there is little understanding of whether interactive surface area is the dominant factor to guide the assembly patterns. Herein by taking millimeter cylinder building blocks with different diameter/height (d/h) ratios as model systems, we have investigated the interactive-surface-area-dependent assembling behaviors in macroscopic supramolecular assembly. The results showed that the increasing d/h ratio of cylinders contributed to selectivity of face-to-face assembled pattern over face-to-side or side-to-side geometries, thus having improved the ordering degree of the assembled structures; however, the mismatching phenomena could not be totally avoided due to high colliding chances in kinetics and the thermally favorable stability of these structures. We further confirmed the above hypothesis by in situ measurements of interactive forces of building blocks with different assembled patterns. This work of macroscopic supramolecular assembly provides an in situ visible platform, which is significant to clarify the influences of interactive surface area on the assembly behaviors.
Uncertain structural dynamics of aircraft panels and fuzzy structures analysis
NASA Astrophysics Data System (ADS)
Sparrow, Victor W.; Buehrle, Ralph D.
2002-11-01
Aircraft fuselage panels, seemingly simple structures, are actually complex because of the uncertainty of the attachments of the frame stiffeners and longitudinal stringers. It is clearly important to understand the dynamics of these panels because of the subsequent radiation into the passenger cabin, even when complete information is not available for all portions of the finite-element model. Over the last few years a fuzzy structures analysis (FSA) approach has been undertaken at Penn State and NASA Langley to quantify the uncertainty in modeling aircraft panels. A new MSC.Nastran [MSC.Software Corp. (Santa Ana, CA)] Direct Matrix Abstraction Program (DMAP) code was written and tested [AIAA paper 2001-1320, 42nd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conf., Seattle, WA, 16 April 2001] and was applied to simple fuselage panel models [J. Acoust. Soc. Am. 109, 2410(A) (2001)]. Recently the work has focused on understanding the dynamics of a realistic aluminum fuselage panel, typical of today's aircraft construction. This presentation will provide an overview of the research and recent results will be given for the fuselage panel. Comparison between experiments and the FSA results will be shown for different fuzzy input parameters. [Work supported by NASA Research Cooperative Agreement NCC-1-382.
The assembly of C. elegans lamins into macroscopic fibers.
Zingerman-Koladko, Irena; Khayat, Maayan; Harapin, Jan; Shoseyov, Oded; Gruenbaum, Yosef; Salman, Ahmad; Medalia, Ohad; Ben-Harush, Kfir
2016-10-01
Intermediate filament (IF) proteins are known mainly by their propensity to form viscoelastic filamentous networks within cells. In addition, IF-proteins are essential parts of various biological materials, such as horn and hagfish slime threads, which exhibit a range of mechanical properties from hard to elastic. These properties and their self-assembly nature made IF-proteins attractive building blocks for biomimetic and biological materials in diverse applications. Here we show that a type V IF-protein, the Caenorhabditis elegans nuclear lamin (Ce-lamin), is a promising building block for protein-based fibers. Electron cryo-tomography of vitrified sections enabled us to depict the higher ordered assembly of the Ce-lamin into macroscopic fibers through the creation of paracrystalline fibers, which are prominent in vitro structures of lamins. The lamin fibers respond to tensile force as other IF-protein-based fibers, i.e., hagfish slime threads, and possess unique mechanical properties that may potentially be used in certain applications. The self-assembly nature of lamin proteins into a filamentous structure, which is further assembled into a complex network, can be easily modulated. This knowledge may lead to a better understanding of the relationship in IF-proteins-based fibers and materials, between their hierarchical structures and their mechanical properties.
The assembly of C. elegans lamins into macroscopic fibers.
Zingerman-Koladko, Irena; Khayat, Maayan; Harapin, Jan; Shoseyov, Oded; Gruenbaum, Yosef; Salman, Ahmad; Medalia, Ohad; Ben-Harush, Kfir
2016-10-01
Intermediate filament (IF) proteins are known mainly by their propensity to form viscoelastic filamentous networks within cells. In addition, IF-proteins are essential parts of various biological materials, such as horn and hagfish slime threads, which exhibit a range of mechanical properties from hard to elastic. These properties and their self-assembly nature made IF-proteins attractive building blocks for biomimetic and biological materials in diverse applications. Here we show that a type V IF-protein, the Caenorhabditis elegans nuclear lamin (Ce-lamin), is a promising building block for protein-based fibers. Electron cryo-tomography of vitrified sections enabled us to depict the higher ordered assembly of the Ce-lamin into macroscopic fibers through the creation of paracrystalline fibers, which are prominent in vitro structures of lamins. The lamin fibers respond to tensile force as other IF-protein-based fibers, i.e., hagfish slime threads, and possess unique mechanical properties that may potentially be used in certain applications. The self-assembly nature of lamin proteins into a filamentous structure, which is further assembled into a complex network, can be easily modulated. This knowledge may lead to a better understanding of the relationship in IF-proteins-based fibers and materials, between their hierarchical structures and their mechanical properties. PMID:27341289
Stochastic Simulation Tool for Aerospace Structural Analysis
NASA Technical Reports Server (NTRS)
Knight, Norman F.; Moore, David F.
2006-01-01
Stochastic simulation refers to incorporating the effects of design tolerances and uncertainties into the design analysis model and then determining their influence on the design. A high-level evaluation of one such stochastic simulation tool, the MSC.Robust Design tool by MSC.Software Corporation, has been conducted. This stochastic simulation tool provides structural analysts with a tool to interrogate their structural design based on their mathematical description of the design problem using finite element analysis methods. This tool leverages the analyst's prior investment in finite element model development of a particular design. The original finite element model is treated as the baseline structural analysis model for the stochastic simulations that are to be performed. A Monte Carlo approach is used by MSC.Robust Design to determine the effects of scatter in design input variables on response output parameters. The tool was not designed to provide a probabilistic assessment, but to assist engineers in understanding cause and effect. It is driven by a graphical-user interface and retains the engineer-in-the-loop strategy for design evaluation and improvement. The application problem for the evaluation is chosen to be a two-dimensional shell finite element model of a Space Shuttle wing leading-edge panel under re-entry aerodynamic loading. MSC.Robust Design adds value to the analysis effort by rapidly being able to identify design input variables whose variability causes the most influence in response output parameters.
Coupled Aerodynamic-Thermal-Structural (CATS) Analysis
NASA Technical Reports Server (NTRS)
1995-01-01
Coupled Aerodynamic-Thermal-Structural (CATS) Analysis is a focused effort within the Numerical Propulsion System Simulation (NPSS) program to streamline multidisciplinary analysis of aeropropulsion components and assemblies. Multidisciplinary analysis of axial-flow compressor performance has been selected for the initial focus of this project. CATS will permit more accurate compressor system analysis by enabling users to include thermal and mechanical effects as an integral part of the aerodynamic analysis of the compressor primary flowpath. Thus, critical details, such as the variation of blade tip clearances and the deformation of the flowpath geometry, can be more accurately modeled and included in the aerodynamic analyses. The benefits of this coupled analysis capability are (1) performance and stall line predictions are improved by the inclusion of tip clearances and hot geometries, (2) design alternatives can be readily analyzed, and (3) higher fidelity analysis by researchers in various disciplines is possible. The goals for this project are a 10-percent improvement in stall margin predictions and a 2:1 speed-up in multidisciplinary analysis times. Working cooperatively with Pratt & Whitney, the Lewis CATS team defined the engineering processes and identified the software products necessary for streamlining these processes. The basic approach is to integrate the aerodynamic, thermal, and structural computational analyses by using data management and Non-Uniform Rational B-Splines (NURBS) based data mapping. Five software products have been defined for this task: (1) a primary flowpath data mapper, (2) a two-dimensional data mapper, (3) a database interface, (4) a blade structural pre- and post-processor, and (5) a computational fluid dynamics code for aerothermal analysis of the drum rotor. Thus far (1) a cooperative agreement has been established with Pratt & Whitney, (2) a Primary Flowpath Data Mapper has been prototyped and delivered to General Electric
Structural analysis of light aircraft using NASTRAN
NASA Technical Reports Server (NTRS)
Wilkinson, M. T.; Bruce, A. C.
1973-01-01
An application of NASTRAN to the structural analysis of light aircraft was conducted to determine the cost effectiveness. A model of the Baby Ace D model homebuilt aircraft was used. The NASTRAN model of the aircraft consists of 193 grid points connected by 352 structural members. All members are either rod or beam elements, including bending of unsymmetrical cross sections and torsion of noncircular cross sections. The aerodynamic loads applied to the aircraft were in accordance with FAA regulations governing the utility category aircraft.
Estrada, Nicolas; Lizcano, Arcesio; Taboada, Alfredo
2010-07-01
This is the second of two papers investigating the mechanical response of cemented granular materials by means of contact dynamics simulations. In this paper, a two-dimensional polydisperse sample with high void ratio is sheared in a load-controlled simple shear numerical device until the stress state of the sample reaches the yield stress. We first study the stress transmission properties of the granular material in terms of the fabric of different subsets of contacts characterized by the magnitude of their normal forces. This analysis highlights the existence of a peculiar force carrying structure in the cemented material, which is reminiscent of the bimodal stress transmission reported for cohesionless granular media. Then, the evolution of contact forces and torques is investigated trying to identify the micromechanical conditions that trigger macroscopic yielding. It is shown that global failure can be associated to the apparition of a group of particles whose contacts fulfill at least one of the local rupture conditions. In particular, these particles form a large region that percolates through the sample at the moment of failure, evidencing the relationship between macroscopic yielding and the emergence of large-scale correlations in the system.
Estrada, Nicolas; Lizcano, Arcesio; Taboada, Alfredo
2010-07-01
This is the second of two papers investigating the mechanical response of cemented granular materials by means of contact dynamics simulations. In this paper, a two-dimensional polydisperse sample with high void ratio is sheared in a load-controlled simple shear numerical device until the stress state of the sample reaches the yield stress. We first study the stress transmission properties of the granular material in terms of the fabric of different subsets of contacts characterized by the magnitude of their normal forces. This analysis highlights the existence of a peculiar force carrying structure in the cemented material, which is reminiscent of the bimodal stress transmission reported for cohesionless granular media. Then, the evolution of contact forces and torques is investigated trying to identify the micromechanical conditions that trigger macroscopic yielding. It is shown that global failure can be associated to the apparition of a group of particles whose contacts fulfill at least one of the local rupture conditions. In particular, these particles form a large region that percolates through the sample at the moment of failure, evidencing the relationship between macroscopic yielding and the emergence of large-scale correlations in the system. PMID:20866608
Coupled structural/thermal/electromagnetic analysis/tailoring of graded composite structures
NASA Technical Reports Server (NTRS)
Mcknight, R. L.; Huang, H.; Hartle, M.
1992-01-01
Accomplishments are described for the third years effort of a 5-year program to develop a methodology for coupled structural/thermal/electromagnetic analysis/tailoring of graded composite structures. These accomplishments include: (1) structural analysis capability specialized for graded composite structures including large deformation and deformation position eigenanalysis technologies; (2) a thermal analyzer specialized for graded composite structures; (3) absorption of electromagnetic waves by graded composite structures; and (4) coupled structural thermal/electromagnetic analysis of graded composite structures.
Structural analysis of ITER magnet feeders
Ilyin, Yuri; Gung, Chen-Yu; Bauer, Pierre; Chen, Yonghua; Jong, Cornelis; Devred, Arnaud; Mitchell, Neil; Lorriere, Philippe; Farek, Jaromir; Nannini, Matthieu
2012-06-15
This paper summarizes the results of the static structural analyses, which were conducted in support of the ITER magnet feeder design with the aim of validating certain components against the structural design criteria. While almost every feeder has unique features, they all share many common constructional elements and the same functional specifications. The analysis approach to assess the load conditions and stresses that have driven the design is equivalent for all feeders, except for particularities that needed to be modeled in each case. The mechanical analysis of the feeders follows the sub-modeling approach: the results of the global mechanical model of a feeder assembly are used as input for the detailed models of the feeder' sub-assemblies or single components. Examples of such approach, including the load conditions, stress assessment criteria and solutions for the most critical components, are discussed. It has been concluded that the feeder system is safe in the referential operation scenarios. (authors)
Analysis of Open TEM-Waveguide Structures
NASA Astrophysics Data System (ADS)
Rambousky, R.; Garbe, H.
This work belongs to a research project on the analysis and characterization of higher order modes occurring in open TEM-waveguide structures. An open TEM waveguide, derived from a conventional GTEM cell by removing the sidewalls, is investigated. The intrinsic resonances of the electromagnetic field occurring in the test volume of the waveguide are analyzed in frequency domain by computer simulation and measurement. This resonance behavior is compared to that of more simplified wire models, describing just the planar septum of the original TEM waveguide. The influence of the number of wires used in the wire model is investigated with respect to the resonant behavior. The use of wire structures is a prerequisite for application of transmission-line super theory (TLST) for further analysis.
Modeling Dissociation-Vibration Coupling with the Macroscopic Chemistry Method
NASA Astrophysics Data System (ADS)
Lilley, Charles R.; Macrossan, Michael N.
2005-05-01
We test the recently developed macroscopic approach to modeling chemistry in DSMC, by simulating the flow of rarefied dissociating nitrogen over a blunt cylinder. In this macroscopic method, chemical reactions are decoupled from the collision routine. Molecules are chosen to undergo dissociation at each time step, after the collisions are calculated. The required number of reaction events is calculated from macroscopic reaction rate expressions with macroscopic information taken from the time-averaged cell properties. One advantage of this method is that "state-of-the-art" macroscopic information about reaction rates can be used directly in DSMC in the same way as in continuum codes. Hybrid Navier-Stokes/DSMC codes can therefore easily use the same chemical models in both rarefied and continuum flow regions. Here we show that the macroscopic method can capture dissociation-vibration (DV) coupling, which is an important effect in vibrationally cold blunt body flows because it results in increased surface heat fluxes. We use the macroscopic method with Park's two-temperature rate model, often used in continuum studies, to capture DV coupling in DSMC. This produces a flowfield in reasonable agreement with that calculated using the conventional collision-based threshold line dissociation model.
CARES - CERAMICS ANALYSIS AND RELIABILITY EVALUATION OF STRUCTURES
NASA Technical Reports Server (NTRS)
Nemeth, N. N.
1994-01-01
The beneficial properties of structural ceramics include their high-temperature strength, light weight, hardness, and corrosion and oxidation resistance. For advanced heat engines, ceramics have demonstrated functional abilities at temperatures well beyond the operational limits of metals. This is offset by the fact that ceramic materials tend to be brittle. When a load is applied, their lack of significant plastic deformation causes the material to crack at microscopic flaws, destroying the component. CARES calculates the fast-fracture reliability or failure probability of macroscopically isotropic ceramic components. These components may be subjected to complex thermomechanical loadings. The program uses results from a commercial structural analysis program (MSC/NASTRAN or ANSYS) to evaluate component reliability due to inherent surface and/or volume type flaws. A multiple material capability allows the finite element model reliability to be a function of many different ceramic material statistical characterizations. The reliability analysis uses element stress, temperature, area, and volume output, which are obtained from two dimensional shell and three dimensional solid isoparametric or axisymmetric finite elements. CARES utilizes the Batdorf model and the two-parameter Weibull cumulative distribution function to describe the effects of multi-axial stress states on material strength. The shear-sensitive Batdorf model requires a user-selected flaw geometry and a mixed-mode fracture criterion. Flaws intersecting the surface and imperfections embedded in the volume can be modeled. The total strain energy release rate theory is used as a mixed mode fracture criterion for co-planar crack extension. Out-of-plane crack extension criteria are approximated by a simple equation with a semi-empirical constant that can model the maximum tangential stress theory, the minimum strain energy density criterion, the maximum strain energy release rate theory, or experimental
Structural analysis at aircraft conceptual design stage
NASA Astrophysics Data System (ADS)
Mansouri, Reza
In the past 50 years, computers have helped by augmenting human efforts with tremendous pace. The aircraft industry is not an exception. Aircraft industry is more than ever dependent on computing because of a high level of complexity and the increasing need for excellence to survive a highly competitive marketplace. Designers choose computers to perform almost every analysis task. But while doing so, existing effective, accurate and easy to use classical analytical methods are often forgotten, which can be very useful especially in the early phases of the aircraft design where concept generation and evaluation demands physical visibility of design parameters to make decisions [39, 2004]. Structural analysis methods have been used by human beings since the very early civilization. Centuries before computers were invented; the pyramids were designed and constructed by Egyptians around 2000 B.C, the Parthenon was built by the Greeks, around 240 B.C, Dujiangyan was built by the Chinese. Persepolis, Hagia Sophia, Taj Mahal, Eiffel tower are only few more examples of historical buildings, bridges and monuments that were constructed before we had any advancement made in computer aided engineering. Aircraft industry is no exception either. In the first half of the 20th century, engineers used classical method and designed civil transport aircraft such as Ford Tri Motor (1926), Lockheed Vega (1927), Lockheed 9 Orion (1931), Douglas DC-3 (1935), Douglas DC-4/C-54 Skymaster (1938), Boeing 307 (1938) and Boeing 314 Clipper (1939) and managed to become airborne without difficulty. Evidencing, while advanced numerical methods such as the finite element analysis is one of the most effective structural analysis methods; classical structural analysis methods can also be as useful especially during the early phase of a fixed wing aircraft design where major decisions are made and concept generation and evaluation demands physical visibility of design parameters to make decisions
Probabilistic seismic demand analysis of nonlinear structures
NASA Astrophysics Data System (ADS)
Shome, Nilesh
Recent earthquakes in California have initiated improvement in current design philosophy and at present the civil engineering community is working towards development of performance-based earthquake engineering of structures. The objective of this study is to develop efficient, but accurate procedures for probabilistic analysis of nonlinear seismic behavior of structures. The proposed procedures help the near-term development of seismic-building assessments which require an estimation of seismic demand at a given intensity level. We also develop procedures to estimate the probability of exceedance of any specified nonlinear response level due to future ground motions at a specific site. This is referred as Probabilistic Seismic Demand Analysis (PSDA). The latter procedure prepares the way for the next stage development of seismic assessment that consider the uncertainties in nonlinear response and capacity. The proposed procedures require structure-specific nonlinear analyses for a relatively small set of recorded accelerograms and (site-specific or USGS-map-like) seismic hazard analyses. We have addressed some of the important issues of nonlinear seismic demand analysis, which are selection of records for structural analysis, the number of records to be used, scaling of records, etc. Initially these issues are studied through nonlinear analysis of structures for a number of magnitude-distance bins of records. Subsequently we introduce regression analysis of response results against spectral acceleration, magnitude, duration, etc., which helps to resolve these issues more systematically. We illustrate the demand-hazard calculations through two major example problems: a 5story and a 20-story SMRF building. Several simple, but quite accurate closed-form solutions have also been proposed to expedite the demand-hazard calculations. We find that vector-valued (e.g., 2-D) PSDA estimates demand hazard more accurately. This procedure, however, requires information about 2
Wideband sensitivity analysis of plasmonic structures
NASA Astrophysics Data System (ADS)
Ahmed, Osman S.; Bakr, Mohamed H.; Li, Xun; Nomura, Tsuyoshi
2013-03-01
We propose an adjoint variable method (AVM) for efficient wideband sensitivity analysis of the dispersive plasmonic structures. Transmission Line Modeling (TLM) is exploited for calculation of the structure sensitivities. The theory is developed for general dispersive materials modeled by Drude or Lorentz model. Utilizing the dispersive AVM, sensitivities are calculated with respect to all the designable parameters regardless of their number using at most one extra simulation. This is significantly more efficient than the regular finite difference approaches whose computational overhead scales linearly with the number of design parameters. A Z-domain formulation is utilized to allow for the extension of the theory to a general material model. The theory has been successfully applied to a structure with teethshaped plasmonic resonator. The design variables are the shape parameters (widths and thicknesses) of these teeth. The results are compared to the accurate yet expensive finite difference approach and good agreement is achieved.
Interval prediction in structural dynamic analysis
NASA Technical Reports Server (NTRS)
Hasselman, Timothy K.; Chrostowski, Jon D.; Ross, Timothy J.
1992-01-01
Methods for assessing the predictive accuracy of structural dynamic models are examined with attention given to the effects of modal mass, stiffness, and damping uncertainties. The methods are based on a nondeterministic analysis called 'interval prediction' in which interval variables are used to describe parameters and responses that are unknown. Statistical databases for generic modeling uncertainties are derived from experimental data and incorporated analytically to evaluate responses. Covariance matrices of modal mass, stiffness, and damping parameters are propagated numerically in models of large space structures by means of three methods. The test data tend to fall within the predicted intervals of uncertainty determined by the statistical databases. The present findings demonstrate the suitability of using data from previously analyzed and tested space structures for assessing the predictive accuracy of an analytical model.
Phase analysis of amplitude binary mask structures
NASA Astrophysics Data System (ADS)
Puthankovilakam, Krishnaparvathy; Scharf, Toralf; Herzig, Hans Peter; Vogler, Uwe; Bramati, Arianna; Voelkel, Reinhard
2016-03-01
Shaping of light behind masks using different techniques is the milestone of the printing industry. The aerial image distribution or the intensity distribution at the printing distances defines the resolution of the structure after printing. Contrast and phase are the two parameters that play a major role in shaping of light to get the desired intensity pattern. Here, in contrast to many other contributions that focus on intensity, we discuss the phase evolution for different structures. The amplitude or intensity characteristics of the structures in a binary mask at different proximity gaps have been analyzed extensively for many industrial applications. But the phase evolution from the binary mask having OPC structures is not considered so far. The mask we consider here is the normal amplitude binary mask but having high resolution Optical Proximity Correction (OPC) structures for corners. The corner structures represent a two dimensional problem which is difficult to handle with simple rules of phase masks design and therefore of particular interest. The evolution of light from small amplitude structures might lead to high contrast by creating sharp phase changes or phase singularities which are points of zero intensity. We show the phase modulation at different proximity gaps and can visualize the shaping of light according to the phase changes. The analysis is done with an instrument called High Resolution Interference Microscopy (HRIM), a Mach-Zehnder interferometer that gives access to three-dimensional phase and amplitude images. The current paper emphasizes on the phase measurement of different optical proximity correction structures, and especially on corners of a binary mask.
Joshi, J.R.
2000-06-20
The Process, Purification and Stack Buildings are collocated safety related concrete shear wall structures with plan dimensions in excess of 100 feet. An important aspect of their seismic analysis was the determination of structure soil structure interaction (SSSI) effects, if any. The SSSI analysis of the Process Building, with one other building at a time, was performed with the SASSI computer code for up to 50 frequencies. Each combined model had about 1500 interaction nodes. Results of the SSSI analysis were compared with those from soil structure interaction (SSI) analysis of the individual buildings, done with ABAQUS and SASSI codes, for three parameters: peak accelerations, seismic forces and the in-structure floor response spectra (FRS). The results may be of wider interest due to the model size and the potential applicability to other deep soil layered sites. Results obtained from the ABAQUS analysis were consistently higher, as expected, than those from the SSI and SSSI analyses using the SASSI. The SSSI effect between the Process and Purification Buildings was not significant. The Process and Stack Building results demonstrated that under certain conditions a massive structure can have an observable effect on the seismic response of a smaller and less stiff structure.
Remote geologic structural analysis of Yucca Flat
NASA Astrophysics Data System (ADS)
Foley, M. G.; Heasler, P. G.; Hoover, K. A.; Rynes, N. J.; Thiessen, R. L.; Alfaro, J. L.
1991-12-01
The Remote Geologic Analysis (RGA) system was developed by Pacific Northwest Laboratory (PNL) to identify crustal structures that may affect seismic wave propagation from nuclear tests. Using automated methods, the RGA system identifies all valleys in a digital elevation model (DEM), fits three-dimensional vectors to valley bottoms, and catalogs all potential fracture or fault planes defined by coplanar pairs of valley vectors. The system generates a cluster hierarchy of planar features having greater-than-random density that may represent areas of anomalous topography manifesting structural control of erosional drainage development. Because RGA uses computer methods to identify zones of hypothesized control of topography, ground truth using a well-characterized test site was critical in our evaluation of RGA's characterization of inaccessible test sites for seismic verification studies. Therefore, we applied RGA to a study area centered on Yucca Flat at the Nevada Test Site (NTS) and compared our results with both mapped geology and geologic structures and with seismic yield-magnitude models. This is the final report of PNL's RGA development project for peer review within the U.S. Department of Energy Office of Arms Control (OAC) seismic-verification community. In this report, we discuss the Yucca Flat study area, the analytical basis of the RGA system and its application to Yucca Flat, the results of the analysis, and the relation of the analytical results to known topography, geology, and geologic structures.
Remote geologic structural analysis of Yucca Flat
Foley, M.G.; Heasler, P.G.; Hoover, K.A. ); Rynes, N.J. ); Thiessen, R.L.; Alfaro, J.L. )
1991-12-01
The Remote Geologic Analysis (RGA) system was developed by Pacific Northwest Laboratory (PNL) to identify crustal structures that may affect seismic wave propagation from nuclear tests. Using automated methods, the RGA system identifies all valleys in a digital elevation model (DEM), fits three-dimensional vectors to valley bottoms, and catalogs all potential fracture or fault planes defined by coplanar pairs of valley vectors. The system generates a cluster hierarchy of planar features having greater-than-random density that may represent areas of anomalous topography manifesting structural control of erosional drainage development. Because RGA uses computer methods to identify zones of hypothesized control of topography, ground truth using a well-characterized test site was critical in our evaluation of RGA's characterization of inaccessible test sites for seismic verification studies. Therefore, we applied RGA to a study area centered on Yucca Flat at the Nevada Test Site (NTS) and compared our results with both mapped geology and geologic structures and with seismic yield-magnitude models. This is the final report of PNL's RGA development project for peer review within the US Department of Energy Office of Arms Control (OAC) seismic-verification community. In this report, we discuss the Yucca Flat study area, the analytical basis of the RGA system and its application to Yucca Flat, the results of the analysis, and the relation of the analytical results to known topography, geology, and geologic structures. 41 refs., 39 figs., 2 tabs.
Remote geologic structural analysis of Yucca Flat
Foley, M.G.; Heasler, P.G.; Hoover, K.A.; Rynes, N.J.; Thiessen, R.L.; Alfaro, J.L.
1991-12-01
The Remote Geologic Analysis (RGA) system was developed by Pacific Northwest Laboratory (PNL) to identify crustal structures that may affect seismic wave propagation from nuclear tests. Using automated methods, the RGA system identifies all valleys in a digital elevation model (DEM), fits three-dimensional vectors to valley bottoms, and catalogs all potential fracture or fault planes defined by coplanar pairs of valley vectors. The system generates a cluster hierarchy of planar features having greater-than-random density that may represent areas of anomalous topography manifesting structural control of erosional drainage development. Because RGA uses computer methods to identify zones of hypothesized control of topography, ground truth using a well-characterized test site was critical in our evaluation of RGA`s characterization of inaccessible test sites for seismic verification studies. Therefore, we applied RGA to a study area centered on Yucca Flat at the Nevada Test Site (NTS) and compared our results with both mapped geology and geologic structures and with seismic yield-magnitude models. This is the final report of PNL`s RGA development project for peer review within the US Department of Energy Office of Arms Control (OAC) seismic-verification community. In this report, we discuss the Yucca Flat study area, the analytical basis of the RGA system and its application to Yucca Flat, the results of the analysis, and the relation of the analytical results to known topography, geology, and geologic structures. 41 refs., 39 figs., 2 tabs.
Nanospheres, nanotubes, toroids, and gels with controlled macroscopic chirality.
Arias, Sandra; Freire, Félix; Quiñoá, Emilio; Riguera, Ricardo
2014-12-01
The interaction of a highly dynamic poly(aryl acetylene) (poly-1) with Li(+), Na(+), and Ag(+) leads to macroscopically chiral supramolecular nanospheres, nanotubes, toroids, and gels. With Ag(+), nanospheres with M helicity and tunable sizes are generated, which complement those obtained from the same polymer with divalent cations. With Li(+) or Na(+), poly-1 yields chiral nanotubes, gels, or toroids with encapsulating properties and M helicity. Right-handed supramolecular structures can be obtained by using the enantiomeric polymer. The interaction of poly-1 with Na(+) produces nanostructures whose helicity is highly dependent on the solvation state of the cation. Therefore, structures with either of the two helicities can be prepared from the same polymer by manipulation of the cosolvent. Such chiral nanotubes, toroids, and gels have previously not been obtained from helical polymer-metal complexes. Chiral nanospheres made of poly(aryl acetylene) that were previously assembled with metal(II) species can now be obtained with metal(I) species. PMID:25209219
Macroscopic Carbon Nanotube-based 3D Monoliths.
Du, Ran; Zhao, Qiuchen; Zhang, Na; Zhang, Jin
2015-07-15
Carbon nanotubes (CNTs) are one of the most promising carbon allotropes with incredible diverse physicochemical properties, thereby enjoying continuous worldwide attention since their discovery about two decades ago. From the point of view of practical applications, assembling individual CNTs into macroscopic functional and high-performance materials is of paramount importance. For example, multiscaled CNT-based assemblies including 1D fibers, 2D films, and 3D monoliths have been developed. Among all of these, monolithic 3D CNT architectures with porous structures have attracted increasing interest in the last few years. In this form, theoretically all individual CNTs are well connected and fully expose their surfaces. These 3D architectures have huge specific surface areas, hierarchical pores, and interconnected conductive networks, resulting in enhanced mass/electron transport and countless accessible active sites for diverse applications (e.g. catalysis, capacitors, and sorption). More importantly, the monolithic form of 3D CNT assemblies can impart additional application potentials to materials, such as free-standing electrodes, sensors, and recyclable sorbents. However, scaling the properties of individual CNTs to 3D assemblies, improving use of the diverse, structure-dependent properties of CNTs, and increasing the performance-to-cost ratio are great unsolved challenges for their real commercialization. This review aims to provide a comprehensive introduction of this young and energetic field, i.e., CNT-based 3D monoliths, with a focus on the preparation principles, current synthetic methods, and typical applications. Opportunities and challenges in this field are also presented.
Experimental demonstration of macroscopic quantum coherence in Gaussian states
Marquardt, Christoph; Leuchs, Gerd; Andersen, Ulrik L.; Takeno, Yuishi; Yukawa, Mitsuyoshi; Yonezawa, Hidehiro; Furusawa, Akira
2007-09-15
We witness experimentally the presence of macroscopic coherence in Gaussian quantum states using a recently proposed criterion [E. G. Cavalcanti and M. D. Reid, Phys. Rev. Lett. 97 170405 (2006)]. The macroscopic coherence stems from interference between macroscopically distinct states in phase space, and we prove experimentally that a coherent state contains these features with a distance in phase space of 0.51{+-}0.02 shot noise units. This is surprising because coherent states are generally considered being at the border between classical and quantum states, not yet displaying any nonclassical effect. For squeezed and entangled states the effect may be larger but depends critically on the state purity.
Structural Analysis Using Computer Based Methods
NASA Technical Reports Server (NTRS)
Dietz, Matthew R.
2013-01-01
The stiffness of a flex hose that will be used in the umbilical arms of the Space Launch Systems mobile launcher needed to be determined in order to properly qualify ground umbilical plate behavior during vehicle separation post T-0. This data is also necessary to properly size and design the motors used to retract the umbilical arms. Therefore an experiment was created to determine the stiffness of the hose. Before the test apparatus for the experiment could be built, the structure had to be analyzed to ensure it would not fail under given loading conditions. The design model was imported into the analysis software and optimized to decrease runtime while still providing accurate restlts and allow for seamless meshing. Areas exceeding the allowable stresses in the structure were located and modified before submitting the design for fabrication. In addition, a mock up of a deep space habitat and the support frame was designed and needed to be analyzed for structural integrity under different loading conditions. The load cases were provided by the customer and were applied to the structure after optimizing the geometry. Once again, weak points in the structure were located and recommended design changes were made to the customer and the process was repeated until the load conditions were met without exceeding the allowable stresses. After the stresses met the required factors of safety the designs were released for fabrication.
NASA Astrophysics Data System (ADS)
Leinonen, Risto; Asikainen, Mervi A.; Hirvonen, Pekka E.
2015-12-01
[This paper is part of the Focused Collection on Upper Division Physics Courses.] This study concentrates on evaluating the consistency of upper-division students' use of the second law of thermodynamics at macroscopic and microscopic levels. Data were collected by means of a paper and pencil test (N =4 8 ) focusing on the macroscopic and microscopic features of the second law concerned with heat transfer processes. The data analysis was based on a qualitative content analysis where students' responses to the macroscopic- and microscopic-level items were categorized to provide insight into the consistency of the students' ideas; if students relied on the same idea at both levels, they ended up in the same category at both levels, and their use of the second law was consistent. The most essential finding is that a majority of students, 52%-69% depending on the physical system under evaluation, used the second law of thermodynamics consistently at macroscopic and microscopic levels; approximately 40% of the students used it correctly in terms of physics while others relied on erroneous ideas, such as the idea of conserving entropy. The most common inconsistency harbored by 10%-15% of the students (depending on the physical system under evaluation) was students' tendency to consider the number of accessible microstates to remain constant even if the entropy was stated to increase in a similar process; other inconsistencies were only seen in the answers of a few students. In order to address the observed inconsistencies, we would suggest that lecturers should utilize tasks that challenge students to evaluate phenomena at macroscopic and microscopic levels concurrently and tasks that would guide students in their search for contradictions in their thinking.
Structural Analysis of Sandwich Foam Panels
Kosny, Jan; Huo, X. Sharon
2010-04-01
The Sandwich Panel Technologies including Structural Insulated Panels (SIPs) can be used to replace the conventional wooden-frame construction method. The main purpose of this Cooperative Research and Development Agreement (CRADA) between UT-Battelle, LLC and SGI Venture, Inc. was to design a novel high R-value type of metal sandwich panelized technology. This CRADA project report presents design concept discussion and numerical analysis results from thermal performance study of this new building envelope system. The main objective of this work was to develop a basic concept of a new generation of wall panel technologies which will have R-value over R-20 will use thermal mass to improve energy performance in cooling dominated climates and will be 100% termite resistant. The main advantages of using sandwich panels are as follows: (1) better energy saving structural panels with high and uniform overall wall R-value across the elevation that could not be achieved in traditional walls; and (2) reducing the use of raw materials or need for virgin lumber. For better utilization of these Sandwich panels, engineers need to have a thorough understanding of the actual performance of the panels and system. Detailed analysis and study on the capacities and deformation of individual panels and its assembly have to be performed to achieve that goal. The major project activity was to conduct structural analysis of the stresses, strains, load capacities, and deformations of individual sandwich components under various load cases. The analysis simulated the actual loading conditions of the regular residential building and used actual material properties of the steel facings and foam.
Macroscopic modeling for heat and water vapor transfer in dry snow by homogenization.
Calonne, Neige; Geindreau, Christian; Flin, Frédéric
2014-11-26
Dry snow metamorphism, involved in several topics related to cryospheric sciences, is mainly linked to heat and water vapor transfers through snow including sublimation and deposition at the ice-pore interface. In this paper, the macroscopic equivalent modeling of heat and water vapor transfers through a snow layer was derived from the physics at the pore scale using the homogenization of multiple scale expansions. The microscopic phenomena under consideration are heat conduction, vapor diffusion, sublimation, and deposition. The obtained macroscopic equivalent model is described by two coupled transient diffusion equations including a source term arising from phase change at the pore scale. By dimensional analysis, it was shown that the influence of such source terms on the overall transfers can generally not be neglected, except typically under small temperature gradients. The precision and the robustness of the proposed macroscopic modeling were illustrated through 2D numerical simulations. Finally, the effective vapor diffusion tensor arising in the macroscopic modeling was computed on 3D images of snow. The self-consistent formula offers a good estimate of the effective diffusion coefficient with respect to the snow density, within an average relative error of 10%. Our results confirm recent work that the effective vapor diffusion is not enhanced in snow. PMID:25011981
High-throughput imaging of adult fluorescent zebrafish with an LED fluorescence macroscope
Blackburn, Jessica S; Liu, Sali; Raimondi, Aubrey R; Ignatius, Myron S; Salthouse, Christopher D; Langenau, David M
2011-01-01
Zebrafish are a useful vertebrate model for the study of development, behavior, disease and cancer. A major advantage of zebrafish is that large numbers of animals can be economically used for experimentation; however, high-throughput methods for imaging live adult zebrafish had not been developed. Here, we describe protocols for building a light-emitting diode (LED) fluorescence macroscope and for using it to simultaneously image up to 30 adult animals that transgenically express a fluorescent protein, are transplanted with fluorescently labeled tumor cells or are tagged with fluorescent elastomers. These protocols show that the LED fluorescence macroscope is capable of distinguishing five fluorescent proteins and can image unanesthetized swimming adult zebrafish in multiple fluorescent channels simultaneously. The macroscope can be built and used for imaging within 1 day, whereas creating fluorescently labeled adult zebrafish requires 1 hour to several months, depending on the method chosen. The LED fluorescence macroscope provides a low-cost, high-throughput method to rapidly screen adult fluorescent zebrafish and it will be useful for imaging transgenic animals, screening for tumor engraftment, and tagging individual fish for long-term analysis. PMID:21293462
Macroscopic modeling for heat and water vapor transfer in dry snow by homogenization.
Calonne, Neige; Geindreau, Christian; Flin, Frédéric
2014-11-26
Dry snow metamorphism, involved in several topics related to cryospheric sciences, is mainly linked to heat and water vapor transfers through snow including sublimation and deposition at the ice-pore interface. In this paper, the macroscopic equivalent modeling of heat and water vapor transfers through a snow layer was derived from the physics at the pore scale using the homogenization of multiple scale expansions. The microscopic phenomena under consideration are heat conduction, vapor diffusion, sublimation, and deposition. The obtained macroscopic equivalent model is described by two coupled transient diffusion equations including a source term arising from phase change at the pore scale. By dimensional analysis, it was shown that the influence of such source terms on the overall transfers can generally not be neglected, except typically under small temperature gradients. The precision and the robustness of the proposed macroscopic modeling were illustrated through 2D numerical simulations. Finally, the effective vapor diffusion tensor arising in the macroscopic modeling was computed on 3D images of snow. The self-consistent formula offers a good estimate of the effective diffusion coefficient with respect to the snow density, within an average relative error of 10%. Our results confirm recent work that the effective vapor diffusion is not enhanced in snow.
Podoshvedov, Sergey A.; Kim, Jaewan
2006-09-15
We suggest an all-optical scheme to generate entangled superposition of a single photon with macroscopic entangled states for testing macroscopic realism. The scheme consists of source of single photons, a Mach-Zehnder interferometer in routes of which a system of coupled-down converters with type-I phase matching is inserted, and a beam splitter for the other auxiliary modes of the scheme. We use quantization of the pumping modes, depletion of the coherent states passing through the system, and interference effect in the pumping modes in the process of erasing which-path information of the single-photon on exit from the Mach-Zehnder interferometer. We show the macroscopic fields of the output superposition are distinguishable states. This scheme generates macroscopic entangled state that violates Bell's inequality. Moreover, the detailed analysis concerning change of amplitudes of entangled superposition by means of repeating this process many times is accomplished. We show our scheme works without photon number resolving detection and it is robust to detector inefficiency.
Challenge to macroscopic probes of quantum spacetime based on noncommutative geometry.
Amelino-Camelia, Giovanni
2013-09-01
Over the last decade, a growing number of quantum-gravity researchers has been looking for opportunities for the first ever experimental evidence of a Planck-length quantum property of spacetime. These studies are usually based on the analysis of some candidate indirect implications of spacetime quantization, such as a possible curvature of momentum space. Some recent proposals have raised hope that we might also gain direct experimental access to quantum properties of spacetime, by finding evidence of limitations to the measurability of the center-of-mass coordinates of some macroscopic bodies. However, I here observe that the arguments that originally led to speculating about spacetime quantization do not apply to the localization of the center of mass of a macroscopic body. And, I also analyze some popular formalizations of the notion of quantum spacetime, finding that when the quantization of spacetime is Planckian for the constituent particles, then for the center of mass of a composite macroscopic body the quantization of spacetime is much weaker than Planckian. These results suggest that the center-of-mass observables of macroscopic bodies should not provide good opportunities for uncovering quantum properties of spacetime. And, they also raise some conceptual challenges for theories of mechanics in quantum spacetime, in which, for example, free protons and free atoms should feel the effects of spacetime quantization differently.
Molecular Eigensolution Symmetry Analysis and Fine Structure
Harter, William G.; Mitchell, Justin C.
2013-01-01
Spectra of high-symmetry molecules contain fine and superfine level cluster structure related to J-tunneling between hills and valleys on rovibronic energy surfaces (RES). Such graphic visualizations help disentangle multi-level dynamics, selection rules, and state mixing effects including widespread violation of nuclear spin symmetry species. A review of RES analysis compares it to that of potential energy surfaces (PES) used in Born–Oppenheimer approximations. Both take advantage of adiabatic coupling in order to visualize Hamiltonian eigensolutions. RES of symmetric and D2 asymmetric top rank-2-tensor Hamiltonians are compared with Oh spherical top rank-4-tensor fine-structure clusters of 6-fold and 8-fold tunneling multiplets. Then extreme 12-fold and 24-fold multiplets are analyzed by RES plots of higher rank tensor Hamiltonians. Such extreme clustering is rare in fundamental bands but prevalent in hot bands, and analysis of its superfine structure requires more efficient labeling and a more powerful group theory. This is introduced using elementary examples involving two groups of order-6 (C6 and D3~C3v), then applied to families of Oh clusters in SF6 spectra and to extreme clusters. PMID:23344041
Microscopic and Macroscopic Studies on Resistance Responses to Daylily Rust
Technology Transfer Automated Retrieval System (TEKTRAN)
Infection process of Puccinia hemerocallidis, the causal agent of daylily rust, and resistance responses in eight daylily cultivars were studied macroscopically and microscopically. After germination of urediniospores, appressoria formed at the tip of germ tubes and penetrated through stomatal openi...
Hyperspectral unmixing using macroscopic and microscopic mixture models
NASA Astrophysics Data System (ADS)
Close, Ryan; Gader, Paul; Wilson, Joseph
2014-01-01
Macroscopic and microscopic mixture models and algorithms for hyperspectral unmixing are presented. Unmixing algorithms are derived from an objective function. The objective function incorporates the linear mixture model for macroscopic unmixing and a nonlinear mixture model for microscopic unmixing. The nonlinear mixture model is derived from a bidirectional reflectance distribution function for microscopic mixtures. The algorithm is designed to unmix hyperspectral images composed of macroscopic or microscopic mixtures. The mixture types and abundances at each pixel can be estimated directly from the data without prior knowledge of mixture types. Endmembers can also be estimated. Results are presented using synthetic data sets of macroscopic and microscopic mixtures and using well-known, well-characterized laboratory data sets. The unmixing accuracy of this new physics-based algorithm is compared to linear methods and to results published for other nonlinear models. The proposed method achieves the best unmixing accuracy.
Comment on 'How macroscopic properties dictate microscopic probabilities'
Finkelstein, J.
2003-02-01
Aharonov and Reznik have argued [in Phys. Rev A 65, 052116 (2002)] that the form of the probabilistic predictions of quantum theory can be seen to follow from properties of macroscopic systems. An error in their argument is identified.
Nonlinear frequency response analysis of structural vibrations
NASA Astrophysics Data System (ADS)
Weeger, Oliver; Wever, Utz; Simeon, Bernd
2014-12-01
In this paper we present a method for nonlinear frequency response analysis of mechanical vibrations of 3-dimensional solid structures. For computing nonlinear frequency response to periodic excitations, we employ the well-established harmonic balance method. A fundamental aspect for allowing a large-scale application of the method is model order reduction of the discretized equation of motion. Therefore we propose the utilization of a modal projection method enhanced with modal derivatives, providing second-order information. For an efficient spatial discretization of continuum mechanics nonlinear partial differential equations, including large deformations and hyperelastic material laws, we employ the concept of isogeometric analysis. Isogeometric finite element methods have already been shown to possess advantages over classical finite element discretizations in terms of higher accuracy of numerical approximations in the fields of linear vibration and static large deformation analysis. With several computational examples, we demonstrate the applicability and accuracy of the modal derivative reduction method for nonlinear static computations and vibration analysis. Thus, the presented method opens a promising perspective on application of nonlinear frequency analysis to large-scale industrial problems.
Macroscopic quantum effects in intrinsic Josephson junction stacks
NASA Astrophysics Data System (ADS)
Koyama, T.; Machida, M.
2008-09-01
A macroscopic quantum theory for the capacitively-coupled intrinsic Josephson junctions (IJJ’s) is constructed. We clarify the multi-junction effect for the macroscopic quantum tunneling (MQT) to the first resistive branch. It is shown that the escape rate is greatly enhanced by the capacitive coupling between junctions. We also discuss the origin of the N2-enhancement in the escape rate observed in the uniformly switching in Bi-2212 IJJ’s.
Dynamic analysis of flexible multibody structures
NASA Technical Reports Server (NTRS)
Hernried, Alan G.
1989-01-01
A system composed of several interconnected elastic components that may experience large angular motion relative to each other during operation is referred to as a flexible multibody structure. Several formulations were proposed for the determination of the dynamic response of controlled flexible multibody structures. In general, these formulations consist of superposing elastic deformations of the component body onto the large rigid body motion of the component. It was shown that this particular methodology for combining linear structural deformations with nonlinear kinematics can lead to erroneous response predictions when either the beam member is very flexible or the rotational speed is high. In addition, previous formulations introduce constraint equations to define the interrelations among system components. This approach increases the number of equations that must be solved, and may result in contraint violation when numerical error accumulates during the integration process. In order to overcome the difficulties, a new approach was suggested. The approach is essentially a finite element formulation which takes advantage of the fact that many multibody structures are joint dominated. The Large Angle Transient Dynamic Analysis (LATDYN) program for clarity of documentation, ease of use, user friendliness, modeling generality, and accuracy of results was evaluated. This required gaining a working familiarity with the code and performing several case studies.
Probabilistic Computational Methods in Structural Failure Analysis
NASA Astrophysics Data System (ADS)
Krejsa, Martin; Kralik, Juraj
2015-12-01
Probabilistic methods are used in engineering where a computational model contains random variables. Each random variable in the probabilistic calculations contains uncertainties. Typical sources of uncertainties are properties of the material and production and/or assembly inaccuracies in the geometry or the environment where the structure should be located. The paper is focused on methods for the calculations of failure probabilities in structural failure and reliability analysis with special attention on newly developed probabilistic method: Direct Optimized Probabilistic Calculation (DOProC), which is highly efficient in terms of calculation time and the accuracy of the solution. The novelty of the proposed method lies in an optimized numerical integration that does not require any simulation technique. The algorithm has been implemented in mentioned software applications, and has been used several times in probabilistic tasks and probabilistic reliability assessments.
General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures
Liu, Yen Vinokur, Marcel; Panesi, Marco; Sahai, Amal
2015-04-07
This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model’s accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy
General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures.
Liu, Yen; Panesi, Marco; Sahai, Amal; Vinokur, Marcel
2015-04-01
This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model's accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy
On the Inherent Self-Excited Macroscopic Randomness of Chaotic Three-Body Systems
NASA Astrophysics Data System (ADS)
Liao, Shijun; Li, Xiaoming
-excited macroscopic randomness (uncertainty) is inherent and unavailable. This work also implies that an universe could randomly evolve by itself into complicated structures, without any external forces. To emphasize this point, the so-called "molecule-effect" (or "nonbutterfly effect") of chaos is suggested in this paper. All of these reliable computations could deepen our understandings of chaos from physical viewpoints, and reveal a kind of origin of macroscopic randomness/uncertainty.
General multi-group macroscopic modeling for thermo-chemical non-equilibrium gas mixtures.
Liu, Yen; Panesi, Marco; Sahai, Amal; Vinokur, Marcel
2015-04-01
This paper opens a new door to macroscopic modeling for thermal and chemical non-equilibrium. In a game-changing approach, we discard conventional theories and practices stemming from the separation of internal energy modes and the Landau-Teller relaxation equation. Instead, we solve the fundamental microscopic equations in their moment forms but seek only optimum representations for the microscopic state distribution function that provides converged and time accurate solutions for certain macroscopic quantities at all times. The modeling makes no ad hoc assumptions or simplifications at the microscopic level and includes all possible collisional and radiative processes; it therefore retains all non-equilibrium fluid physics. We formulate the thermal and chemical non-equilibrium macroscopic equations and rate coefficients in a coupled and unified fashion for gases undergoing completely general transitions. All collisional partners can have internal structures and can change their internal energy states after transitions. The model is based on the reconstruction of the state distribution function. The internal energy space is subdivided into multiple groups in order to better describe non-equilibrium state distributions. The logarithm of the distribution function in each group is expressed as a power series in internal energy based on the maximum entropy principle. The method of weighted residuals is applied to the microscopic equations to obtain macroscopic moment equations and rate coefficients succinctly to any order. The model's accuracy depends only on the assumed expression of the state distribution function and the number of groups used and can be self-checked for accuracy and convergence. We show that the macroscopic internal energy transfer, similar to mass and momentum transfers, occurs through nonlinear collisional processes and is not a simple relaxation process described by, e.g., the Landau-Teller equation. Unlike the classical vibrational energy
Irreversibility in macroscopic physics: From Carnot cycle to dissipative structures
NASA Astrophysics Data System (ADS)
Glansdorff, P.
1987-07-01
The conceptual foundations of the modern thermodynamic theory related to a large category of far-from-equilibrium phenomena are outlined, and the historical continuity with early developments based on the impossibility of perpetual motion is discussed. In this perspective the discovery of thermodynamic stability criteria around steady or periodic processes, together with a general evolution criterion that is valid in the non-linear region (and thus implying creation of order and applicability to living systems), appears as a most remarkable development indeed. The leading role played by the Brussels school and particularly by Ilya Prigogine is emphasized.
Irreversibility in macroscopic physics: from Carnot cycle to dissipative structures
Glansdorff, P.
1987-07-01
The conceptual foundations of the modern thermodynamic theory related to a large category of far-from-equilibrium phenomena are outlined, and the historical continuity with early developments based on the impossibility of perpetual motion is discussed. In this perspective the discovery of thermodynamic stability criteria around steady or periodic processes, together with a general evolution criterion that is valid in the non-linear region (and thus implying creation of order and applicability to living systems), appears as a most remarkable development indeed. The leading role played by the Brussels school and particularly by Ilya Prigogine is emphasized.
Geometrically nonlinear analysis of laminated elastic structures
NASA Technical Reports Server (NTRS)
Reddy, J. N.
1984-01-01
Laminated composite plates and shells that can be used to model automobile bodies, aircraft wings and fuselages, and pressure vessels among many other were analyzed. The finite element method, a numerical technique for engineering analysis of structures, is used to model the geometry and approximate the solution. Various alternative formulations for analyzing laminated plates and shells are developed and their finite element models are tested for accuracy and economy in computation. These include the shear deformation laminate theory and degenerated 3-D elasticity theory for laminates.
Electrokinetic assembly of selenium and silver nanowires into macroscopic fibers.
Wang, Michael C P; Zhang, Xin; Majidi, Elham; Nedelec, Kevin; Gates, Byron D
2010-05-25
Solution-phase synthesized nanowires with high aspect ratios can be a challenge to assemble into desired structures. As synthesized, these nanostructures readily bend and entangle with each other to form larger aggregates. This manuscript reports a general procedure for directing the assembly of semiconducting and metallic nanowires into fibers that can easily span distances >1 cm. Dispersions of these nanostructures in a low dielectric solution are organized by electrokinetic techniques into fibers that can be isolated from solution. Theoretical studies suggest that the assembled fibers adopt an orientation along electric field lines in the solution. The number of assembled fibers is a function of the duration of the assembly process, the magnitude of the electric potential, and the initial concentration of nanowires dispersed in solution. These findings offer a general method for the assembly of nanowires into macroscopic fibers of tunable dimensions. Fibers of selenium nanowires isolated from solution can reversibly bend in response to a source of electrostatic charges positioned in close proximity to the free-standing fiber. These flexible selenium fibers also exhibit a photoconductive response when illuminated with white light.
Cheng, Mengjiao; Ju, Guannan; Zhang, Yingwei; Song, Mengmeng; Zhang, Yajun; Shi, Feng
2014-10-15
Chemical energy supplied by the catalytic decomposition of H2O2 is introduced into macroscopic building blocks, which self-propel, interact with each other, and finally assemble into ordered and advanced structures. The geometry is highly dependent on the way that the catalyst is loaded. The integration of catalyst and building block provides assembling component as well as its energy of motion. PMID:24838346
Structural reliability analysis of laminated CMC components
NASA Technical Reports Server (NTRS)
Duffy, Stephen F.; Palko, Joseph L.; Gyekenyesi, John P.
1991-01-01
For laminated ceramic matrix composite (CMC) materials to realize their full potential in aerospace applications, design methods and protocols are a necessity. The time independent failure response of these materials is focussed on and a reliability analysis is presented associated with the initiation of matrix cracking. A public domain computer algorithm is highlighted that was coupled with the laminate analysis of a finite element code and which serves as a design aid to analyze structural components made from laminated CMC materials. Issues relevant to the effect of the size of the component are discussed, and a parameter estimation procedure is presented. The estimation procedure allows three parameters to be calculated from a failure population that has an underlying Weibull distribution.
Mitter, Christian; Jakab, András; Brugger, Peter C.; Ricken, Gerda; Gruber, Gerlinde M.; Bettelheim, Dieter; Scharrer, Anke; Langs, Georg; Hainfellner, Johannes A.; Prayer, Daniela; Kasprian, Gregor
2015-01-01
Diffusion tensor imaging (DTI) and tractography offer the unique possibility to visualize the developing white matter macroanatomy of the human fetal brain in vivo and in utero and are currently under investigation for their potential use in the diagnosis of developmental pathologies of the human central nervous system. However, in order to establish in utero DTI as a clinical imaging tool, an independent comparison between macroscopic imaging and microscopic histology data in the same subject is needed. The present study aimed to cross-validate normal as well as abnormal in utero tractography results of commissural and internal capsule fibers in human fetal brains using postmortem histological structure tensor (ST) analysis. In utero tractography findings from two structurally unremarkable and five abnormal fetal brains were compared to the results of postmortem ST analysis applied to digitalized whole hemisphere sections of the same subjects. An approach to perform ST-based deterministic tractography in histological sections was implemented to overcome limitations in correlating in utero tractography to postmortem histology data. ST analysis and histology-based tractography of fetal brain sections enabled the direct assessment of the anisotropic organization and main fiber orientation of fetal telencephalic layers on a micro- and macroscopic scale, and validated in utero tractography results of corpus callosum and internal capsule fiber tracts. Cross-validation of abnormal in utero tractography results could be achieved in four subjects with agenesis of the corpus callosum (ACC) and in two cases with malformations of internal capsule fibers. In addition, potential limitations of current DTI-based in utero tractography could be demonstrated in several brain regions. Combining the three-dimensional nature of DTI-based in utero tractography with the microscopic resolution provided by histological ST analysis may ultimately facilitate a more complete morphologic
Mitter, Christian; Jakab, András; Brugger, Peter C; Ricken, Gerda; Gruber, Gerlinde M; Bettelheim, Dieter; Scharrer, Anke; Langs, Georg; Hainfellner, Johannes A; Prayer, Daniela; Kasprian, Gregor
2015-01-01
Diffusion tensor imaging (DTI) and tractography offer the unique possibility to visualize the developing white matter macroanatomy of the human fetal brain in vivo and in utero and are currently under investigation for their potential use in the diagnosis of developmental pathologies of the human central nervous system. However, in order to establish in utero DTI as a clinical imaging tool, an independent comparison between macroscopic imaging and microscopic histology data in the same subject is needed. The present study aimed to cross-validate normal as well as abnormal in utero tractography results of commissural and internal capsule fibers in human fetal brains using postmortem histological structure tensor (ST) analysis. In utero tractography findings from two structurally unremarkable and five abnormal fetal brains were compared to the results of postmortem ST analysis applied to digitalized whole hemisphere sections of the same subjects. An approach to perform ST-based deterministic tractography in histological sections was implemented to overcome limitations in correlating in utero tractography to postmortem histology data. ST analysis and histology-based tractography of fetal brain sections enabled the direct assessment of the anisotropic organization and main fiber orientation of fetal telencephalic layers on a micro- and macroscopic scale, and validated in utero tractography results of corpus callosum and internal capsule fiber tracts. Cross-validation of abnormal in utero tractography results could be achieved in four subjects with agenesis of the corpus callosum (ACC) and in two cases with malformations of internal capsule fibers. In addition, potential limitations of current DTI-based in utero tractography could be demonstrated in several brain regions. Combining the three-dimensional nature of DTI-based in utero tractography with the microscopic resolution provided by histological ST analysis may ultimately facilitate a more complete morphologic
Fe(II) sorption on a synthetic montmorillonite. A combined macroscopic and spectroscopic study.
Soltermann, Daniela; Fernandes, Maria Marques; Baeyens, Bart; Dähn, Rainer; Miehé-Brendlé, Jocelyne; Wehrli, Bernhard; Bradbury, Michael H
2013-07-01
Extended X-ray absorption fine structure (EXAFS) and Mössbauer spectroscopy combined with macroscopic sorption experiments were employed to investigate the sorption mechanism of Fe(II) on an iron-free synthetic montmorillonite (Na-IFM). Batch sorption experiments were performed to measure the Fe(II) uptake on Na-IFM at trace concentrations as a function of pH and as a function of sorbate concentration at pH 6.2 and 6.7 under anoxic conditions (O2 < 0.1 ppm). A two-site protolysis nonelectrostatic surface complexation and cation exchange sorption model was used to quantitatively describe the uptake of Fe(II) on Na-IFM. Two types of clay surface binding sites were required to model the Fe(II) sorption, the so-called strong (≡S(S)OH) and weak (≡S(W)OH) sites. EXAFS data show spectroscopic differences between Fe sorbed at low and medium absorber concentrations that were chosen to be characteristic for sorption on strong and weak sites, respectively. Data analysis indicates that Fe is located in the continuity of the octahedral sheet at trans-symmetric sites. Mössbauer spectroscopy measurements confirmed that iron sorbed on the weak edge sites is predominantly present as Fe(II), whereas a significant part of surface-bound Fe(III) was produced on the strong sites (∼12% vs ∼37% Fe(III) species to total sorbed Fe).
Niu, Z.; Bruckman, M.; Li, S.; Lee, A.; Lee, B.; Pingali, S.-V.; Thiyagarajan, P.; Wang, Q.; Univ. of South Carolina
2007-06-05
One-dimensional (1D) polyaniline/tobacco mosaic virus (TMV) composite nanofibers and macroscopic bundles of such fibers were generated via a self-assembly process of TMV assisted by in-situ polymerization of polyaniline on the surface of TMV. At near-neutral reaction pH, branched polyaniline formed on the surface of TMV preventing lateral association. Therefore, long 1D nanofibers were observed with high aspect ratios and excellent processibility. At a lower pH, transmission electron microscopy (TEM) analysis revealed that initially long nanofibers were formed which resulted in bundled structures upon long-time reaction, presumably mediated by the hydrophobic interaction because of the polyaniline on the surface of TMV. In-situ time-resolved small-angle X-ray scattering study of TMV at different reaction conditions supported this mechanism. This novel strategy to assemble TMV into 1D and 3D supramolecular composites could be utilized in the fabrication of advanced materials for potential applications including electronics, optics, sensing, and biomedical engineering.
How coupled elementary units determine the dynamics of macroscopic glass-forming systems
NASA Astrophysics Data System (ADS)
Rehwald, Christian; Heuer, Andreas
2012-11-01
We investigate the dynamics of a binary mixture Lennard-Jones system of different system sizes with respect to the importance of the properties of the underlying potential energy landscape (PEL). We show that the dynamics of small systems can be very well described within the continuous time random walk formalism, which is determined solely by PEL parameters. Finite size analysis shows that the diffusivity of large and small systems are very similar. This suggests that the PEL parameters of the small system also determine the local dynamics in large systems. The structural relaxation time, however, displays significant finite size effects. Furthermore, using a nonequilibrium configuration of a large system, we find that causal connections exist between nearby regions of the system. These findings can be described by the coupled landscape model for which a macroscopic system is described by a superposition of elementary systems, each described by its PEL. A minimum coupling is introduced which accounts for the finite size behavior. The coupling strength, as the single adjustable parameter, becomes smaller closer to the glass transition.
Ceramics Analysis and Reliability Evaluation of Structures (CARES). Users and programmers manual
NASA Technical Reports Server (NTRS)
Nemeth, Noel N.; Manderscheid, Jane M.; Gyekenyesi, John P.
1990-01-01
This manual describes how to use the Ceramics Analysis and Reliability Evaluation of Structures (CARES) computer program. The primary function of the code is to calculate the fast fracture reliability or failure probability of macroscopically isotropic ceramic components. These components may be subjected to complex thermomechanical loadings, such as those found in heat engine applications. The program uses results from MSC/NASTRAN or ANSYS finite element analysis programs to evaluate component reliability due to inherent surface and/or volume type flaws. CARES utilizes the Batdorf model and the two-parameter Weibull cumulative distribution function to describe the effect of multiaxial stress states on material strength. The principle of independent action (PIA) and the Weibull normal stress averaging models are also included. Weibull material strength parameters, the Batdorf crack density coefficient, and other related statistical quantities are estimated from four-point bend bar or unifrom uniaxial tensile specimen fracture strength data. Parameter estimation can be performed for single or multiple failure modes by using the least-square analysis or the maximum likelihood method. Kolmogorov-Smirnov and Anderson-Darling goodness-of-fit tests, ninety percent confidence intervals on the Weibull parameters, and Kanofsky-Srinivasan ninety percent confidence band values are also provided. The probabilistic fast-fracture theories used in CARES, along with the input and output for CARES, are described. Example problems to demonstrate various feature of the program are also included. This manual describes the MSC/NASTRAN version of the CARES program.
NASA Technical Reports Server (NTRS)
Dorris, William J.; Hairr, John W.; Huang, Jui-Tien; Ingram, J. Edward; Shah, Bharat M.
1992-01-01
Non-linear analysis methods were adapted and incorporated in a finite element based DIAL code. These methods are necessary to evaluate the global response of a stiffened structure under combined in-plane and out-of-plane loading. These methods include the Arc Length method and target point analysis procedure. A new interface material model was implemented that can model elastic-plastic behavior of the bond adhesive. Direct application of this method is in skin/stiffener interface failure assessment. Addition of the AML (angle minus longitudinal or load) failure procedure and Hasin's failure criteria provides added capability in the failure predictions. Interactive Stiffened Panel Analysis modules were developed as interactive pre-and post-processors. Each module provides the means of performing self-initiated finite elements based analysis of primary structures such as a flat or curved stiffened panel; a corrugated flat sandwich panel; and a curved geodesic fuselage panel. This module brings finite element analysis into the design of composite structures without the requirement for the user to know much about the techniques and procedures needed to actually perform a finite element analysis from scratch. An interactive finite element code was developed to predict bolted joint strength considering material and geometrical non-linearity. The developed method conducts an ultimate strength failure analysis using a set of material degradation models.
Macroscopic Neural Oscillation during Skilled Reaching Movements in Humans
Chung, Chun Kee
2016-01-01
The neural mechanism of skilled movements, such as reaching, has been considered to differ from that of rhythmic movement such as locomotion. It is generally thought that skilled movements are consciously controlled by the brain, while rhythmic movements are usually controlled autonomously by the spinal cord and brain stem. However, several studies in recent decades have suggested that neural networks in the spinal cord may also be involved in the generation of skilled movements. Moreover, a recent study revealed that neural activities in the motor cortex exhibit rhythmic oscillations corresponding to movement frequency during reaching movements as rhythmic movements. However, whether the oscillations are generated in the spinal cord or the cortical circuit in the motor cortex causes the oscillations is unclear. If the spinal cord is involved in the skilled movements, then similar rhythmic oscillations with time delays should be found in macroscopic neural activity. We measured whole-brain MEG signals during reaching. The MEG signals were analyzed using a dynamical analysis method. We found that rhythmic oscillations with time delays occur in all subjects during reaching movements. The results suggest that the corticospinal system is involved in the generation and control of the skilled movements as rhythmic movements. PMID:27524996
LETTERS AND COMMENTS: Adiabatic process reversibility: microscopic and macroscopic views
NASA Astrophysics Data System (ADS)
Anacleto, Joaquim; Pereira, Mário G.
2009-05-01
The reversibility of adiabatic processes was recently addressed by two publications. In the first (Miranda 2008 Eur. J. Phys. 29 937-43), an equation was derived relating the initial and final volumes and temperatures for adiabatic expansions of an ideal gas, using a microscopic approach. In that relation the parameter r accounts for the process reversibility, ranging between 0 and 1, which corresponds to the free and reversible expansion, respectively. In the second (Anacleto and Pereira 2009 Eur. J. Phys. 30 177-83), the authors have shown that thermodynamics can effectively and efficiently be used to obtain the general law for adiabatic processes carried out by an ideal gas, including compressions, for which r \\ge 1. The present work integrates and extends the aforementioned studies, providing thus further insights into the analysis of the adiabatic process. It is shown that Miranda's work is wholly valid for compressions. In addition, it is demonstrated that the adiabatic reversibility coefficient given in terms of the piston velocity and the root mean square velocity of the gas particles is equivalent to the macroscopic description, given just by the quotient between surroundings and system pressure values.
Tinnitus does not require macroscopic tonotopic map reorganization
Langers, Dave R. M.; de Kleine, Emile; van Dijk, Pim
2012-01-01
The pathophysiology underlying tinnitus, a hearing disorder characterized by the chronic perception of phantom sound, has been related to aberrant plastic reorganization of the central auditory system. More specifically, tinnitus is thought to involve changes in the tonotopic representation of sound. In the present study we used high-resolution functional magnetic resonance imaging to determine tonotopic maps in the auditory cortex of 20 patients with tinnitus but otherwise near-normal hearing, and compared these to equivalent outcomes from 20 healthy controls with matched hearing thresholds. Using a dedicated experimental paradigm and data-driven analysis techniques, multiple tonotopic gradients could be robustly distinguished in both hemispheres, arranged in a pattern consistent with previous findings. Yet, maps were not found to significantly differ between the two groups in any way. In particular, we found no evidence for an overrepresentation of high sound frequencies, matching the tinnitus pitch. A significant difference in evoked response magnitude was found near the low-frequency tonotopic endpoint on the lateral extreme of left Heschl’s gyrus. Our results suggest that macroscopic tonotopic reorganization in the auditory cortex is not required for the emergence of tinnitus, and is not typical for tinnitus that accompanies normal hearing to mild hearing loss. PMID:22347171
Properties of nuclear matter from macroscopic-microscopic mass formulas
NASA Astrophysics Data System (ADS)
Wang, Ning; Liu, Min; Ou, Li; Zhang, Yingxun
2015-12-01
Based on the standard Skyrme energy density functionals together with the extended Thomas-Fermi approach, the properties of symmetric and asymmetric nuclear matter represented in two macroscopic-microscopic mass formulas: Lublin-Strasbourg nuclear drop energy (LSD) formula and Weizsäcker-Skyrme (WS*) formula, are extracted through matching the energy per particle of finite nuclei. For LSD and WS*, the obtained incompressibility coefficients of symmetric nuclear matter are K∞ = 230 ± 11 MeV and 235 ± 11 MeV, respectively. The slope parameter of symmetry energy at saturation density is L = 41.6 ± 7.6 MeV for LSD and 51.5 ± 9.6 MeV for WS*, respectively, which is compatible with the liquid-drop analysis of Lattimer and Lim [4]. The density dependence of the mean-field isoscalar and isovector effective mass, and the neutron-proton effective masses splitting for neutron matter are simultaneously investigated. The results are generally consistent with those from the Skyrme Hartree-Fock-Bogoliubov calculations and nucleon optical potentials, and the standard deviations are large and increase rapidly with density. A better constraint for the effective mass is helpful to reduce uncertainties of the depth of the mean-field potential.
Macroscopic Evidence for the Hibernating Behavior of Materials Stock.
Daigo, Ichiro; Iwata, Kohei; Ohkata, Ikumi; Goto, Yoshikazu
2015-07-21
Hibernating stock is defined as material stock that is no longer used, but is not yet recovered. Although hibernating stock plays a role in materials recoverability, its contribution to the overall material cycle is not clearly understood. Therefore, an analysis of the time-series potential generation of steel scrap in Japan was performed and compared against the actual recovery, proving that the steel scrap recovered each year exceeds the annual generation potential and providing the first macroscopic evidence of hibernating stock recovery. These results indicate that hibernation behavior should be considered when evaluating materials recoverability. The particular characteristics of hibernating stock were also identified. These materials tend to be located far from scrap yards and/or have low bulk density, while also minimally obstructing new activity. In fact, hibernating materials are typically only recovered when they obstruct new activity. Hence, in order to increase steel recoverability, the recovery cost must be reduced. The end-of-life recycling rates (EoL-RRs) were also evaluated, and were found to exhibit a significant change over time. Consequently, the annual EoL-RR cannot be considered as a representative value, and a value for the EoL-RR(s) of relevant year(s) that has been evaluated over the entire period should be used instead.
Structure-Function Analysis of Yeast Tubulin
Luchniak, Anna; Fukuda, Yusuke; Gupta, Mohan L.
2014-01-01
Microtubules play essential roles in a wide variety of cellular processes including cell division, motility, and vesicular transport. Microtubule function depends on the polymerization dynamics of tubulin, and specific interactions between tubulin and diverse microtubule-associated proteins. To date, investigation of the structural and functional properties of tubulin and tubulin mutants has been limited by the inability to obtain functional protein from overexpression systems, and by the heterogeneous mixture of tubulin isotypes typically isolated from higher eukaryotes. The budding yeast, Saccharomyces cerevisiae, has emerged as a leading system for tubulin structure-function analysis. Yeast cells encode a single beta-tubulin gene and can be engineered to express just one, of two, alpha isotypes. Moreover, yeast allows site-directed modification of tubulin genes at the endogenous loci expressed under the native promoter and regulatory elements. These advantageous features provide a homogeneous and controlled environment for analysis of the functional consequences of specific mutations. Here we present techniques to generate site-specific tubulin mutations in diploid and haploid cells, assess the ability of the mutated protein to support cell viability, measure overall microtubule stability, and define changes in the specific parameters of microtubule dynamic instability. We also outline strategies to determine whether mutations disrupt interactions with microtubule-associated proteins. Microtubule-based functions in yeast are well defined, which allows the observed changes in microtubule properties to be related to the role of microtubules in specific cellular processes. PMID:23973083
Modeling ancient Egyptian mummification on fresh human tissue: macroscopic and histological aspects.
Papageorgopoulou, Christina; Shved, Natallia; Wanek, Johann; Rühli, Frank J
2015-06-01
Many studies have been concerned with the ancient Egyptian mummification method; nevertheless, little effort has been made to explore it experimentally. The goal of this study is to apply evidence-based diagnostic criteria and state-of-the art methodology in order to improve knowledge on soft tissues preservation and postmortem alterations. Two human lower limbs (LL) from a female donor were (1) "naturally" mummified by dry heat and (2) artificially in natron. At specific time intervals a macroscopic and radiological examination of the LL was performed and skin and muscle samples were taken for histological and biomolecular analysis. Temperature, humidity, pH, and weight of the LL were systematically measured. The mummification by dry heat was stopped after 7 days due to unexpected lack of mummification progress. The mummification in natron was completed successfully after 208 days. The humidity, the external temperature, and the pH were proven with Pearson correlation and principal component analysis as important factors for the mummification process. The steady removal of water from the tissues through the natron has prevented the putrefaction. This is also evident in the absence of bacteria or fungi through the microbiological analysis. The histological analysis revealed very good preservation of the skin and the muscle tissues. In the muscular sample certain degree of structural disintegration can be seen, particularly affecting the epimysium whilst in the skin samples the epidermis, especially the stratum corneum, is mostly affected. The samples show better preservation compared with ancient Egyptian sections and other mummified tissues from historic or forensic context.
NASA Astrophysics Data System (ADS)
Lara-Cabrera, R.; Cotta, C.; Fernández-Leiva, A. J.
2014-02-01
Games constitute a research domain that is attracting the interest of scientists from numerous disciplines. This is particularly true from the perspective of computational intelligence. In order to examine the growing importance of this area in the gaming domain, we present an analysis of the scientific collaboration network of researchers working on computational intelligence in games (CIG). This network has been constructed from bibliographical data obtained from the Digital Bibliography & Library Project (DBLP). We have analyzed from a temporal perspective several properties of the CIG network at the macroscopic, mesoscopic and microscopic levels, studying the large-scale structure, the growth mechanics, and collaboration patterns among other features. Overall, computational intelligence in games exhibits similarities with other collaboration networks such as for example a log-normal degree distribution and sub-linear preferential attachment for new authors. It also has distinctive features, e.g. the number of papers co-authored is exponentially distributed, the internal preferential attachment (new collaborations among existing authors) is linear, and fidelity rates (measured as the relative preference for publishing with previous collaborators) grow super-linearly. The macroscopic and mesoscopic evolution of the network indicates the field is very active and vibrant, but it is still at an early developmental stage. We have also analyzed communities and central nodes and how these are reflected in research topics, thus identifying active research subareas.
Macroscopic hotspots identification: A Bayesian spatio-temporal interaction approach.
Dong, Ni; Huang, Helai; Lee, Jaeyoung; Gao, Mingyun; Abdel-Aty, Mohamed
2016-07-01
This study proposes a Bayesian spatio-temporal interaction approach for hotspot identification by applying the full Bayesian (FB) technique in the context of macroscopic safety analysis. Compared with the emerging Bayesian spatial and temporal approach, the Bayesian spatio-temporal interaction model contributes to a detailed understanding of differential trends through analyzing and mapping probabilities of area-specific crash trends as differing from the mean trend and highlights specific locations where crash occurrence is deteriorating or improving over time. With traffic analysis zones (TAZs) crash data collected in Florida, an empirical analysis was conducted to evaluate the following three approaches for hotspot identification: FB ranking using a Poisson-lognormal (PLN) model, FB ranking using a Bayesian spatial and temporal (B-ST) model and FB ranking using a Bayesian spatio-temporal interaction (B-ST-I) model. The results show that (a) the models accounting for space-time effects perform better in safety ranking than does the PLN model, and (b) the FB approach using the B-ST-I model significantly outperforms the B-ST approach in correctly identifying hotspots by explicitly accounting for the space-time variation in addition to the stable spatial/temporal patterns of crash occurrence. In practice, the B-ST-I approach plays key roles in addressing two issues: (a) how the identified hotspots have evolved over time and (b) the identification of areas that, whilst not yet hotspots, show a tendency to become hotspots. Finally, it can provide guidance to policy decision makers to efficiently improve zonal-level safety.
Macroscopic hotspots identification: A Bayesian spatio-temporal interaction approach.
Dong, Ni; Huang, Helai; Lee, Jaeyoung; Gao, Mingyun; Abdel-Aty, Mohamed
2016-07-01
This study proposes a Bayesian spatio-temporal interaction approach for hotspot identification by applying the full Bayesian (FB) technique in the context of macroscopic safety analysis. Compared with the emerging Bayesian spatial and temporal approach, the Bayesian spatio-temporal interaction model contributes to a detailed understanding of differential trends through analyzing and mapping probabilities of area-specific crash trends as differing from the mean trend and highlights specific locations where crash occurrence is deteriorating or improving over time. With traffic analysis zones (TAZs) crash data collected in Florida, an empirical analysis was conducted to evaluate the following three approaches for hotspot identification: FB ranking using a Poisson-lognormal (PLN) model, FB ranking using a Bayesian spatial and temporal (B-ST) model and FB ranking using a Bayesian spatio-temporal interaction (B-ST-I) model. The results show that (a) the models accounting for space-time effects perform better in safety ranking than does the PLN model, and (b) the FB approach using the B-ST-I model significantly outperforms the B-ST approach in correctly identifying hotspots by explicitly accounting for the space-time variation in addition to the stable spatial/temporal patterns of crash occurrence. In practice, the B-ST-I approach plays key roles in addressing two issues: (a) how the identified hotspots have evolved over time and (b) the identification of areas that, whilst not yet hotspots, show a tendency to become hotspots. Finally, it can provide guidance to policy decision makers to efficiently improve zonal-level safety. PMID:27110645
Structural Analysis of the JET TAE Antenna
Titus, P.H.; Snipes, J.; Fasoli, A.F.; Testa, D.; Walton, B.
2005-05-15
In this paper the mechanical design of the new active MHD antennas for JET is described and the structural/mechanical analysis for the antennas is presented. These new antennas replace the existing n = 1 or 2 saddle coils with a set of eight smaller antennas designed to excite Toroidal Alfven Eigenmodes (TAE's) with high toroidal mode number (n {approx} 10) in the frequency range of 30 kHz-500 kHz. TAE's with these higher mode numbers are expected in ITER and could enhance the loss of fast alpha particles in a burning plasma regime. By studying the properties of stable TAE's excited actively by these antennas, high performance regimes of operation avoiding unstable fast particle driven modes can be found. A more complete overview of the experiment may be found in Reference 1. Two antenna assemblies will be installed at toroidally opposite positions. Antenna wires are protected from the plasma heat flux by CFC tiles mounted on mini-limiters, located between the individual windings. The main structural element is a box section. The support scheme utilizes cantilevered brackets that connect to the saddle coils, and 'wing' brackets which add support to the top of the frame. Conservative estimates of the disruption currents in the MHD antennas and frame were used to calculate loading and resulting stress in the antenna structure. Fields, field transients, and halo current specifications were provided by JET. The frame originally was designed as a continuous loop, and was converted to an open structure to break eddy current loops. Antenna eddy currents were computed assuming the antenna is shorted. In the final design, frame forces primarily result from halo currents entering around the mini limiters that now protect the antenna windings. Accelerations due to the vessel disruption dynamic response were included in the loading. The antenna mechanical design has been shown to perform adequately for all identified disruption loading.
Atomic-level analysis of membrane-protein structure.
Hendrickson, Wayne A
2016-06-01
Membrane proteins are substantially more challenging than natively soluble proteins as subjects for structural analysis. Thus, membrane proteins are greatly underrepresented in structural databases. Recently, focused consortium efforts and advances in methodology for protein production, crystallographic analysis and cryo-EM analysis have accelerated the pace of atomic-level structure determination of membrane proteins.
Direct growth of macroscopic fibers composed of large diameter SWNTs by CVD
NASA Astrophysics Data System (ADS)
Yang, Q. H.; Bai, S.; Fournier, T.; Li, F.; Wang, G.; Cheng, H. M.; Bai, J. B.
2003-03-01
Macroscopic nanotube fibers, composed of aligned large diameter single-walled carbon nanotubes (SWNTs), were prepared by a simple CVD method. These fibers, which constitute the nanotube ropes of loose structure like hemp cords, can be divided into the nanotube threads (mesoscopically) and subdivided into nanotube bundles (microscopically). The samples show good alignment at different scales. The fibers, several micrometers in diameter, have a relatively stable structure and only dissociated partially under ultrasonic dispersion. The obtained SWNTs have good crystalline structure and good purity. The influence of the CVD conditions on the fiber morphology was also investigated.
Nuclear magnetic resonance studies of macroscopic morphology and dynamics
Barrall, G A
1995-09-01
Nuclear magnetic resonance techniques are traditionally used to study molecular level structure and dynamics with a noted exception in medically applied NMR imaging (MRI). In this work, new experimental methods and theory are presented relevant to the study of macroscopic morphology and dynamics using NMR field gradient techniques and solid state two-dimensional exchange NMR. The goal in this work is not to take some particular system and study it in great detail, rather it is to show the utility of a number of new and novel techniques using ideal systems primarily as a proof of principle. By taking advantage of the analogy between NMR imaging and diffraction, one may simplify the experiments necessary for characterizing the statistical properties of the sample morphology. For a sample composed of many small features, e.g. a porous medium, the NMR diffraction techniques take advantage of both the narrow spatial range and spatial isotropy of the sample`s density autocorrelation function to obtain high resolution structural information in considerably less time than that required by conventional NMR imaging approaches. The time savings of the technique indicates that NMR diffraction is capable of finer spatial resolution than conventional NMR imaging techniques. Radio frequency NMR imaging with a coaxial resonator represents the first use of cylindrically symmetric field gradients in imaging. The apparatus as built has achieved resolution at the micron level for water samples, and has the potential to be very useful in the imaging of circularly symmetric systems. The study of displacement probability densities in flow through a random porous medium has revealed the presence of features related to the interconnectedness of the void volumes. The pulsed gradient techniques used have proven successful at measuring flow properties for time and length scales considerably shorter than those studied by more conventional techniques.
Bacterial Macroscopic Rope-like Fibers with Cytopathic and Adhesive Properties*
Xicohtencatl-Cortes, Juan; Saldaña, Zeus; Deng, Wanyin; Castañeda, Elsa; Freer, Enrique; Tarr, Phil I.; Finlay, B. Brett; Puente, José Luis; Girón, Jorge A.
2010-01-01
We present a body of ultrastructural, biochemical, and genetic evidence that demonstrates the oligomerization of virulence-associated autotransporter proteins EspC or EspP produced by deadly human pathogens enterohemorrhagic and enteropathogenic Escherichia coli into novel macroscopic rope-like structures (>1 cm long). The rope-like structures showed high aggregation and insolubility, stability to anionic detergents and high temperature, and binding to Congo Red and thioflavin T dyes. These are properties also exhibited by human amyloidogenic proteins. These macroscopic ropes were not observed in cultures of nonpathogenic Escherichia coli or isogenic espP or espC deletion mutants of enterohemorrhagic or enteropathogenic Escherichia coli but were produced by an Escherichia coli K-12 strain carrying a plasmid expressing espP. Purified recombinant EspP monomers were able to self-assemble into macroscopic ropes upon incubation, suggesting that no other protein was required for assembly. The ropes bound to and showed cytopathic effects on cultured epithelial cells, served as a substratum for bacterial adherence and biofilm formation, and protected bacteria from antimicrobial compounds. We hypothesize that these ropes play a biologically significant role in the survival and pathogenic scheme of these organisms. PMID:20688909
NASA Astrophysics Data System (ADS)
Lunn, David J.; Gould, Oliver E. C.; Whittell, George R.; Armstrong, Daniel P.; Mineart, Kenneth P.; Winnik, Mitchell A.; Spontak, Richard J.; Pringle, Paul G.; Manners, Ian
2016-08-01
Anisotropic nanoparticles prepared from block copolymers are of growing importance as building blocks for the creation of synthetic hierarchical materials. However, the assembly of these structural units is generally limited to the use of amphiphilic interactions. Here we report a simple, reversible coordination-driven hierarchical self-assembly strategy for the preparation of micron-scale fibres and macroscopic films based on monodisperse cylindrical block copolymer micelles. Coordination of Pd(0) metal centres to phosphine ligands immobilized within the soluble coronas of block copolymer micelles is found to induce intermicelle crosslinking, affording stable linear fibres comprised of micelle subunits in a staggered arrangement. The mean length of the fibres can be varied by altering the micelle concentration, reaction stoichiometry or aspect ratio of the micelle building blocks. Furthermore, the fibres aggregate on drying to form robust, self-supporting macroscopic micelle-based thin films with useful mechanical properties that are analogous to crosslinked polymer networks, but on a longer length scale.
Lunn, David J; Gould, Oliver E C; Whittell, George R; Armstrong, Daniel P; Mineart, Kenneth P; Winnik, Mitchell A; Spontak, Richard J; Pringle, Paul G; Manners, Ian
2016-08-19
Anisotropic nanoparticles prepared from block copolymers are of growing importance as building blocks for the creation of synthetic hierarchical materials. However, the assembly of these structural units is generally limited to the use of amphiphilic interactions. Here we report a simple, reversible coordination-driven hierarchical self-assembly strategy for the preparation of micron-scale fibres and macroscopic films based on monodisperse cylindrical block copolymer micelles. Coordination of Pd(0) metal centres to phosphine ligands immobilized within the soluble coronas of block copolymer micelles is found to induce intermicelle crosslinking, affording stable linear fibres comprised of micelle subunits in a staggered arrangement. The mean length of the fibres can be varied by altering the micelle concentration, reaction stoichiometry or aspect ratio of the micelle building blocks. Furthermore, the fibres aggregate on drying to form robust, self-supporting macroscopic micelle-based thin films with useful mechanical properties that are analogous to crosslinked polymer networks, but on a longer length scale.
Study of Fission Barrier Heights of Uranium Isotopes by the Macroscopic-Microscopic Method
NASA Astrophysics Data System (ADS)
Zhong, Chun-Lai; Fan, Tie-Shuan
2014-09-01
Potential energy surfaces of uranium nuclei in the range of mass numbers 229 through 244 are investigated in the framework of the macroscopic-microscopic model and the heights of static fission barriers are obtained in terms of a double-humped structure. The macroscopic part of the nuclear energy is calculated according to Lublin—Strasbourg-drop (LSD) model. Shell and pairing corrections as the microscopic part are calculated with a folded-Yukawa single-particle potential. The calculation is carried out in a five-dimensional parameter space of the generalized Lawrence shapes. In order to extract saddle points on the potential energy surface, a new algorithm which can effectively find an optimal fission path leading from the ground state to the scission point is developed. The comparison of our results with available experimental data and others' theoretical results confirms the reliability of our calculations.
Structure Tensor Based Analysis of Cells and Nuclei Organization in Tissues.
Zhang, Wenxing; Fehrenbach, Jérôme; Desmaison, Annaïck; Lobjois, Valérie; Ducommun, Bernard; Weiss, Pierre
2016-01-01
Extracting geometrical information from large 2D or 3D biomedical images is important to better understand fundamental phenomena such as morphogenesis. We address the problem of automatically analyzing spatial organization of cells or nuclei in 2D or 3D images of tissues. This problem is challenging due to the usually low quality of microscopy images as well as their typically large sizes. The structure tensor is a simple and robust descriptor that was developed to analyze textures orientation. Contrarily to segmentation methods which rely on an object based modeling of images, the structure tensor considers the sample at a macroscopic scale, like a continuous medium. We show that this tool allows quantifying two important features of nuclei in tissues: their privileged orientation as well as the ratio between the length of their main axes. A quantitative evaluation of the method is provided for synthetic and real 2D and 3D images. As an application, we analyze the nuclei orientation and anisotropy on multicellular tumor spheroids cryosections. This analysis reveals that cells are elongated in a privileged direction that is parallel to the spheroid boundary. A MATLAB toolbox and an Icy plugin are available to use the proposed method.
Purification and Structural Analysis of Desmoplakin.
Choi, Hee-Jung; Weis, William I
2016-01-01
Desmoplakin (DP) is an obligate component of desmosomes, where it links the desmosomal cadherin/plakoglobin/plakophilin assembly to intermediate filaments. DP contains a large amino-terminal domain (DPNT) that binds to the cadherin/plakoglobin/plakophilin complex, a central coiled-coil domain that dimerizes the molecule, and a C-terminal domain (DPCT) that binds to intermediate filaments. DPNT contains a plakin domain, comprising a set of spectrin-like repeats. DPCT contains three plakin repeat domains, each formed by 4.5 repeats of a sequence motif known as a plakin repeat that bind to intermediate filaments. Here, we review purification, biochemical characterization, and structural analysis of the DPNT plakin domain and the DPCT plakin repeat domains.
Recent developments in structural sensitivity analysis
NASA Technical Reports Server (NTRS)
Haftka, Raphael T.; Adelman, Howard M.
1988-01-01
Recent developments are reviewed in two major areas of structural sensitivity analysis: sensitivity of static and transient response; and sensitivity of vibration and buckling eigenproblems. Recent developments from the standpoint of computational cost, accuracy, and ease of implementation are presented. In the area of static response, current interest is focused on sensitivity to shape variation and sensitivity of nonlinear response. Two general approaches are used for computing sensitivities: differentiation of the continuum equations followed by discretization, and the reverse approach of discretization followed by differentiation. It is shown that the choice of methods has important accuracy and implementation implications. In the area of eigenproblem sensitivity, there is a great deal of interest and significant progress in sensitivity of problems with repeated eigenvalues. In addition to reviewing recent contributions in this area, the paper raises the issue of differentiability and continuity associated with the occurrence of repeated eigenvalues.
Random motion analysis of flexible satellite structures
NASA Technical Reports Server (NTRS)
Huang, T. C.; Das, A.
1978-01-01
A singular perturbation formulation is used to study the responses of a flexible satellite when random measurement errors can occur. The random variables, at different instants of time, are assumed to be uncorrelated. Procedures for obtaining maxima and minima are described, and a variation of the linear method is developed for the formal solution of the two-point boundary-value problems represented by the variational equations. Random and deterministic solutions for the structural position coordinates are studied, and an analytic algorithm for treating the force equation of motion is developed. Since the random system indicated by the variational equation will always be asymptotically unstable, any analysis of stability must be based on the deterministic system.
Structural analysis of nucleosomal barrier to transcription
Gaykalova, Daria A.; Kulaeva, Olga I.; Volokh, Olesya; Shaytan, Alexey K.; Hsieh, Fu-Kai; Kirpichnikov, Mikhail P.; Sokolova, Olga S.; Studitsky, Vasily M.
2015-01-01
Thousands of human and Drosophila genes are regulated at the level of transcript elongation and nucleosomes are likely targets for this regulation. However, the molecular mechanisms of formation of the nucleosomal barrier to transcribing RNA polymerase II (Pol II) and nucleosome survival during/after transcription remain unknown. Here we show that both DNA–histone interactions and Pol II backtracking contribute to formation of the barrier and that nucleosome survival during transcription likely occurs through allosterically stabilized histone–histone interactions. Structural analysis indicates that after Pol II encounters the barrier, the enzyme backtracks and nucleosomal DNA recoils on the octamer, locking Pol II in the arrested state. DNA is displaced from one of the H2A/H2B dimers that remains associated with the octamer. The data reveal the importance of intranucleosomal DNA–protein and protein–protein interactions during conformational changes in the nucleosome structure on transcription. Mechanisms of nucleosomal barrier formation and nucleosome survival during transcription are proposed. PMID:26460019
Analysis of structures with rotating, flexible substructures
NASA Technical Reports Server (NTRS)
Hopkins, A. Stewart; Likins, Peter
1987-01-01
A new methodology has been developed for the dynamic analysis of flexible structures, parts of which may be experiencing discrete motion relative to other parts. This methodology provides the capability of representing the continuum deformations typically treated using finite element methods. In addition, it provides the capability of representing the discrete motion at joints traditionally available with multibody methods. After decomposing the structure into substructures and associating a frame of reference with each substructure, the equations of motion for each substructure can be written explicitly including contributions due to the frame of reference generalized coordinates. By expanding the set of constraints to include constraints that eliminate the redundancy introduced by the frame generalized coordinates, the equations of motion become amenable to solution. The first digital computer program using this methodology, the General Rotorcraft Aeromechanical Stability Program (GRASP), was introduced in 1986. Although GRASP is limited to applications involving steady-state rotation, extension to arbitrary motions (including spin-up) can be accomplished by the selective retention of nonlinear terms in this formulation.
Extracting Macroscopic Information from Web Links.
ERIC Educational Resources Information Center
Thelwall, Mike
2001-01-01
Discussion of Web-based link analysis focuses on an evaluation of Ingversen's proposed external Web Impact Factor for the original use of the Web, namely the interlinking of academic research. Studies relationships between academic hyperlinks and research activities for British universities and discusses the use of search engines for Web link…
Nanostructure surveys of macroscopic specimens by small-angle scattering tensor tomography
NASA Astrophysics Data System (ADS)
Liebi, Marianne; Georgiadis, Marios; Menzel, Andreas; Schneider, Philipp; Kohlbrecher, Joachim; Bunk, Oliver; Guizar-Sicairos, Manuel
2015-11-01
The mechanical properties of many materials are based on the macroscopic arrangement and orientation of their nanostructure. This nanostructure can be ordered over a range of length scales. In biology, the principle of hierarchical ordering is often used to maximize functionality, such as strength and robustness of the material, while minimizing weight and energy cost. Methods for nanoscale imaging provide direct visual access to the ultrastructure (nanoscale structure that is too small to be imaged using light microscopy), but the field of view is limited and does not easily allow a full correlative study of changes in the ultrastructure over a macroscopic sample. Other methods of probing ultrastructure ordering, such as small-angle scattering of X-rays or neutrons, can be applied to macroscopic samples; however, these scattering methods remain constrained to two-dimensional specimens or to isotropically oriented ultrastructures. These constraints limit the use of these methods for studying nanostructures with more complex orientation patterns, which are abundant in nature and materials science. Here, we introduce an imaging method that combines small-angle scattering with tensor tomography to probe nanoscale structures in three-dimensional macroscopic samples in a non-destructive way. We demonstrate the method by measuring the main orientation and the degree of orientation of nanoscale mineralized collagen fibrils in a human trabecula bone sample with a spatial resolution of 25 micrometres. Symmetries within the sample, such as the cylindrical symmetry commonly observed for mineralized collagen fibrils in bone, allow for tractable sampling requirements and numerical efficiency. Small-angle scattering tensor tomography is applicable to both biological and materials science specimens, and may be useful for understanding and characterizing smart or bio-inspired materials. Moreover, because the method is non-destructive, it is appropriate for in situ measurements and
Structures and Analysis of Carotenoid Molecules.
Rodriguez-Amaya, Delia B
2016-01-01
Modifications of the usual C40 linear and symmetrical carotenoid skeleton give rise to a wide array of structures of carotenes and xanthophylls in plant tissues. These include acyclic, monocyclic and dicyclic carotenoids, along with hydroxy and epoxy xanthophylls and apocarotenoids. Carotenols can be unesterified or esterified (monoester) in one or two (diester) hydroxyl groups with fatty acids. E-Z isomerization increases the array of possible plant carotenoids even further. Screening and especially quantitative analysis are being carried out worldwide. Visible absorption spectrometry and near infrared reflectance spectroscopy have been used for the initial estimation of the total carotenoid content or the principal carotenoid content when large numbers of samples needed to be analyzed within a short time, as would be the case in breeding programs. Although inherently difficult, quantitative analysis of the individual carotenoids is essential. Knowledge of the sources of errors and means to avoid them has led to a large body of reliable quantitative compositional data on carotenoids. Reverse-phase HPLC with a photodiode array detector has been the preferred analytical technique, but UHPLC is increasingly employed. HPLC-MS has been used mainly for identification and NMR has been useful in unequivocally identifying geometric isomers. PMID:27485219
Structure/load dependent vectors for linear structural dynamic analysis
NASA Technical Reports Server (NTRS)
Qin, Jiangning; Nguyen, Duc T.
1992-01-01
The dynamic solution vectors yielded by the present structure/load dependent-vectors method for large-scale linear structural dynamic analyses involving complex loadings can be used as starting vectors, so that both structure and load characteristics are encompassed by the basis vectors. The method is shown to entail fewer vectors than current alternatives for a given level of accuracy, especially in the cases of structures that have external concentrated masses. Numerical results are presented which illustrate the advantages of this dependent-vectors method relative to other reduction methods.
NASA Astrophysics Data System (ADS)
Yoon, Peter H.; Seough, Jungjoon; Hwang, Junga; Nariyuki, Yasuhiro
2015-08-01
The protons and helium ions in the solar wind are observed to possess anisotropic temperature profiles. The anisotropy appears to be limited by various marginal instability conditions. One of the efficient methods to investigate the global dynamics and distribution of various temperature anisotropies in the large-scale solar wind models may be that based upon the macroscopic quasi-linear approach. The present paper investigates the proton and helium ion anisotropy instabilities on the basis of the quasi-linear theory versus particle-in-cell simulation. It is found that the overall dynamical development of the particle temperatures is quite accurately reproduced by the macroscopic quasi-linear scheme. The wave energy development in time, however, shows somewhat less restrictive comparisons, indicating that while the quasi-linear method is acceptable for the particle dynamics, the wave analysis probably requires higher-order physics, such as wave-wave coupling or nonlinear wave-particle interaction.
Graphene chiral liquid crystals and macroscopic assembled fibres
NASA Astrophysics Data System (ADS)
Xu, Zhen; Gao, Chao
2011-12-01
Chirality and liquid crystals are both widely expressed in nature and biology. Helical assembly of mesophasic molecules and colloids may produce intriguing chiral liquid crystals. To date, chiral liquid crystals of 2D colloids have not been explored. As a typical 2D colloid, graphene is now receiving unprecedented attention. However, making macroscopic graphene fibres is hindered by the poor dispersibility of graphene and by the lack of an assembly method. Here we report that soluble, chemically oxidized graphene or graphene oxide sheets can form chiral liquid crystals in a twist-grain-boundary phase-like model with simultaneous lamellar ordering and long-range helical frustrations. Aqueous graphene oxide liquid crystals were continuously spun into metres of macroscopic graphene oxide fibres; subsequent chemical reduction gave the first macroscopic neat graphene fibres with high conductivity and good mechanical performance. The flexible, strong graphene fibres were knitted into designed patterns and into directionally conductive textiles.
Graphene chiral liquid crystals and macroscopic assembled fibres
Xu, Zhen; Gao, Chao
2011-01-01
Chirality and liquid crystals are both widely expressed in nature and biology. Helical assembly of mesophasic molecules and colloids may produce intriguing chiral liquid crystals. To date, chiral liquid crystals of 2D colloids have not been explored. As a typical 2D colloid, graphene is now receiving unprecedented attention. However, making macroscopic graphene fibres is hindered by the poor dispersibility of graphene and by the lack of an assembly method. Here we report that soluble, chemically oxidized graphene or graphene oxide sheets can form chiral liquid crystals in a twist-grain-boundary phase-like model with simultaneous lamellar ordering and long-range helical frustrations. Aqueous graphene oxide liquid crystals were continuously spun into metres of macroscopic graphene oxide fibres; subsequent chemical reduction gave the first macroscopic neat graphene fibres with high conductivity and good mechanical performance. The flexible, strong graphene fibres were knitted into designed patterns and into directionally conductive textiles. PMID:22146390
[Studies on macroscopic and microscopic characteristics of Ophiocordyceps xuefengensis].
Liu, Hao; Zhen, Lan-ping; Zhu, Ru-cai; Zhang, Shui-han; Huang, Hui-yong
2015-07-01
The macroscopic characteristics, tissue, caterpillar body wall and powder of Ophiocordyceps xuefengensis in different batch numbers were observed and researched by the macroscopic and microscopic identification methods. The result shows that the morphology, size, abdominal annulations of caterpillar, etc. of 0. xuefengensis are the macroscopic identification characteristics, the caterpillar body surface mycelium, body wall sculpture and crochets on abdominal legs are the microscopic identification characteristics. These characters are stable and regular discriminant features, which are proved to be the identification basis of O. xuefengensis. In addition, The characters such as crochets on abdominal legs arrange in two parallel ellipse rings, the inner crochets are long strip, and the external toes are unciform, are specific. PMID:26666033
Atomistic Simulation of the Transition from Atomistic to Macroscopic Cratering
Samela, Juha; Nordlund, Kai
2008-07-11
Using large-scale atomistic simulations, we show that the macroscopic cratering behavior emerges for projectile impacts on Au at projectile sizes between 1000 and 10 000 Au atoms at impact velocities comparable to typical meteoroid velocities. In this size regime, we detect a compression of material in Au nanoparticle impacts similar to that observed for hypervelocity macroscopic impacts. The simulated crater volumes agree with the values calculated using the macroscopic crater size scaling law, in spite of a downwards extrapolation over more than 15 orders of magnitude in terms of the impactor volume. The result demonstrates that atomistic simulations can be used as a tool to understand the strength properties of materials in cases where only continuum models have been possible before.
Macroscopic quantumness: Theory and applications in optical sciences
NASA Astrophysics Data System (ADS)
Jeong, Hyunseok; Sasaki, Masahide
2015-02-01
Since the early days of quantum mechanics, as illustrated by Schrödinger's Gedankenexperiment, macroscopic quantum phenomena have attracted great interest among scientists and general audience. As highlighted by the Nobel prize in Physics in 2012, the scientific community could assent that the state-of-the-art technology to measure and manipulate individual quantum systems is now available in laboratories. We believe that the next step in order is to collectively control large quantum systems even at a 'macroscopic' level. This will be an intriguing challenge, from the fundamental point of view, for testing quantum mechanics in the macroscopic limit. Furthermore, it will make another major step forward to practical implementations of quantum information technologies.
Optimal Estimation of Ion-Channel Kinetics from Macroscopic Currents
Zeng, Xuhui; Yao, Jing; Yuchi, Ming; Ding, Jiuping
2012-01-01
Markov modeling provides an effective approach for modeling ion channel kinetics. There are several search algorithms for global fitting of macroscopic or single-channel currents across different experimental conditions. Here we present a particle swarm optimization(PSO)-based approach which, when used in combination with golden section search (GSS), can fit macroscopic voltage responses with a high degree of accuracy (errors within 1%) and reasonable amount of calculation time (less than 10 hours for 20 free parameters) on a desktop computer. We also describe a method for initial value estimation of the model parameters, which appears to favor identification of global optimum and can further reduce the computational cost. The PSO-GSS algorithm is applicable for kinetic models of arbitrary topology and size and compatible with common stimulation protocols, which provides a convenient approach for establishing kinetic models at the macroscopic level. PMID:22536358
Broadband macroscopic cortical oscillations emerge from intrinsic neuronal response failures.
Goldental, Amir; Vardi, Roni; Sardi, Shira; Sabo, Pinhas; Kanter, Ido
2015-01-01
Broadband spontaneous macroscopic neural oscillations are rhythmic cortical firing which were extensively examined during the last century, however, their possible origination is still controversial. In this work we show how macroscopic oscillations emerge in solely excitatory random networks and without topological constraints. We experimentally and theoretically show that these oscillations stem from the counterintuitive underlying mechanism-the intrinsic stochastic neuronal response failures (NRFs). These NRFs, which are characterized by short-term memory, lead to cooperation among neurons, resulting in sub- or several- Hertz macroscopic oscillations which coexist with high frequency gamma oscillations. A quantitative interplay between the statistical network properties and the emerging oscillations is supported by simulations of large networks based on single-neuron in-vitro experiments and a Langevin equation describing the network dynamics. Results call for the examination of these oscillations in the presence of inhibition and external drives. PMID:26578893
Role of macroscopic particles in deep-sea oxygen consumption.
Bochdansky, Alexander B; van Aken, Hendrik M; Herndl, Gerhard J
2010-05-01
Macroscopic particles (>500 mum), including marine snow, large migrating zooplankton, and their fast-sinking fecal pellets, represent primary vehicles of organic carbon flux from the surface to the deep sea. In contrast, freely suspended microscopic particles such as bacteria and protists do not sink, and they contribute the largest portion of metabolism in the upper ocean. In bathy- and abyssopelagic layers of the ocean (2,000-6,000 m), however, microscopic particles may not dominate oxygen consumption. In a section across the tropical Atlantic, we show that macroscopic particle peaks occurred frequently in the deep sea, whereas microscopic particles were barely detectable. In 10 of 17 deep-sea profiles (>2,000 m depth), macroscopic particle abundances were more strongly cross-correlated with oxygen deficits than microscopic particles, suggesting that biomass bound to large particles dominates overall deep-sea metabolism.
Broadband macroscopic cortical oscillations emerge from intrinsic neuronal response failures
Goldental, Amir; Vardi, Roni; Sardi, Shira; Sabo, Pinhas; Kanter, Ido
2015-01-01
Broadband spontaneous macroscopic neural oscillations are rhythmic cortical firing which were extensively examined during the last century, however, their possible origination is still controversial. In this work we show how macroscopic oscillations emerge in solely excitatory random networks and without topological constraints. We experimentally and theoretically show that these oscillations stem from the counterintuitive underlying mechanism—the intrinsic stochastic neuronal response failures (NRFs). These NRFs, which are characterized by short-term memory, lead to cooperation among neurons, resulting in sub- or several- Hertz macroscopic oscillations which coexist with high frequency gamma oscillations. A quantitative interplay between the statistical network properties and the emerging oscillations is supported by simulations of large networks based on single-neuron in-vitro experiments and a Langevin equation describing the network dynamics. Results call for the examination of these oscillations in the presence of inhibition and external drives. PMID:26578893
Microscopic to Macroscopic Dynamical Models of Sociality
NASA Astrophysics Data System (ADS)
Solis Salas, Citlali; Woolley, Thomas; Pearce, Eiluned; Dunbar, Robin; Maini, Philip; Social; Evolutionary Neuroscience Research Group (Senrg) Collaboration
To help them survive, social animals, such as humans, need to share knowledge and responsibilities with other members of the species. The larger their social network, the bigger the pool of knowledge available to them. Since time is a limited resource, a way of optimising its use is meeting amongst individuals whilst fulfilling other necessities. In this sense it is useful to know how many, and how often, early humans could meet during a given period of time whilst performing other necessary tasks, such as food gathering. Using a simplified model of these dynamics, which comprehend encounter and memory, we aim at producing a lower-bound to the number of meetings hunter-gatherers could have during a year. We compare the stochastic agent-based model to its mean-field approximation and explore some of the features necessary for the difference between low population dynamics and its continuum limit. We observe an emergent property that could have an inference in the layered structure seen in each person's social organisation. This could give some insight into hunter-gatherer's lives and the development of the social layered structure we have today. With support from the Mexican Council for Science and Technology (CONACyT), the Public Education Secretariat (SEP), and the Mexican National Autonomous University's Foundation (Fundacion UNAM).
Innovations in macroscopic evaluation of pancreatic specimens and radiologic correlation.
Triantopoulou, Charikleia; Papaparaskeva, Kleo; Agalianos, Christos; Dervenis, Christos
2016-01-01
The purpose of this study was to evaluate the feasibility of a novel dissection technique of surgical specimens in different cases of pancreatic tumors and provide a radiologic pathologic correlation. In our hospital, that is a referral center for pancreatic diseases, the macroscopic evaluation of the pancreatectomy specimens is performed by the pathologists using the axial slicing technique (instead of the traditional procedure with longitudinal opening of the main pancreatic and/or common bile duct and slicing along the plane defined by both ducts). The specimen is sliced in an axial plane that is perpendicular to the longitudinal axis of the descending duodenum. The procedure results in a large number of thin slices (3-4 mm). This plane is identical to that of CT or MRI and correlation between pathology and imaging is straightforward. We studied 70 cases of suspected different solid and cystic pancreatic tumors and we correlated the tumor size and location, the structure-consistency (areas of necrosis-hemorrhage-fibrosis-inflammation), the degree of vessels' infiltration, the size of pancreatic and common bile duct and the distance from resection margins. Missed findings by imaging or pitfalls were recorded and we tried to explain all discrepancies between radiology evaluation and the histopathological findings. Radiologic-pathologic correlation is extremely important, adding crucial information on imaging limitations and enabling quality assessment of surgical specimens. The deep knowledge of different pancreatic tumors' consistency and way of extension helps to improve radiologists' diagnostic accuracy and minimize the radiological-surgical mismatching, preventing patients from unnecessary surgery. PMID:27069980
Macroscopicity in an optomechanical matter-wave interferometer
NASA Astrophysics Data System (ADS)
Xuereb, André; Ulbricht, Hendrik; Paternostro, Mauro
2015-02-01
We analyse a proposal that we have recently put forward for an interface between matter-wave and optomechanical technologies from the perspective of macroscopic quantumness. In particular, by making use of a measure of macroscopicity in quantum superpositions that is particularly well suited for continuous variables systems, we demonstrate the existence of working points for our interface at which a quantum mechanical superposition of genuinely mesoscopic states is achieved. Our proposal thus holds the potential to affirm itself as a viable atom-to-mechanics transducer of quantum coherences.
A review of macroscopic ductile failure criteria.
Corona, Edmundo; Reedlunn, Benjamin
2013-09-01
The objective of this work was to describe several of the ductile failure criteria com- monly used to solve practical problems. The following failure models were considered: equivalent plastic strain, equivalent plastic strain in tension, maximum shear, Mohr- Coulomb, Wellman's tearing parameter, Johnson-Cook and BCJ MEM. The document presents the main characteristics of each failure model as well as sample failure predic- tions for simple proportional loading stress histories in three dimensions and in plane stress. Plasticity calculations prior to failure were conducted with a simple, linear hardening, J2 plasticity model. The resulting failure envelopes were plotted in prin- cipal stress space and plastic strain space, where the dependence on stress triaxiality and Lode angle are clearly visible. This information may help analysts select a ductile fracture model for a practical problem and help interpret analysis results.
Studies into the averaging problem: Macroscopic gravity and precision cosmology
NASA Astrophysics Data System (ADS)
Wijenayake, Tharake S.
With the tremendous improvement in the precision of available astrophysical data in the recent past, it becomes increasingly important to examine some of the underlying assumptions behind the standard model of cosmology and take into consideration nonlinear and relativistic corrections which may affect it at percent precision level. Due to its mathematical rigor and fully covariant and exact nature, Zalaletdinov's macroscopic gravity (MG) is arguably one of the most promising frameworks to explore nonlinearities due to inhomogeneities in the real Universe. We study the application of MG to precision cosmology, focusing on developing a self-consistent cosmology model built on the averaging framework that adequately describes the large-scale Universe and can be used to study real data sets. We first implement an algorithmic procedure using computer algebra systems to explore new exact solutions to the MG field equations. After validating the process with an existing isotropic solution, we derive a new homogeneous, anisotropic and exact solution. Next, we use the simplest (and currently only) solvable homogeneous and isotropic model of MG and obtain an observable function for cosmological expansion using some reasonable assumptions on light propagation. We find that the principal modification to the angular diameter distance is through the change in the expansion history. We then linearize the MG field equations and derive a framework that contains large-scale structure, but the small scale inhomogeneities have been smoothed out and encapsulated into an additional cosmological parameter representing the averaging effect. We derive an expression for the evolution of the density contrast and peculiar velocities and integrate them to study the growth rate of large-scale structure. We find that increasing the magnitude of the averaging term leads to enhanced growth at late times. Thus, for the same matter content, the growth rate of large scale structure in the MG model
Macroscopic Graphene Fibers Directly Assembled from CVD-Grown Fiber-Shaped Hollow Graphene Tubes.
Chen, Tao; Dai, Liming
2015-12-01
Using a copper wire as the substrate for the CVD growth of a hollow multilayer graphene tube, we prepared a macroscopic porous graphene fiber by removing the copper in an aqueous mixture solution of iron chloride (FeCl3, 1 M) and hydrochloric acid (HCl, 3 M) and continuously drawing the newly released graphene tube out of the liquid. The length of the macroscopic graphene fiber thus produced is determined mainly by the length of the copper wire used. The resultant macroscopic graphene fiber with the integrated graphene structure exhibited a high electrical conductivity (127.3 S cm(-1)) and good flexibility over thousands bending cycles, showing great promise as flexible electrodes for wearable optoelectronics and energy devices-exemplified by its use as a flexible conductive wire for lighting a LED and a cathode in a fiber-shaped dye-sensitized solar cell (DSSC) with one of the highest energy conversion efficiencies (3.25%) among fiber-shaped DSSCs. PMID:26473977
Macroscopic Models of Local Field Potentials and the Apparent 1/f Noise in Brain Activity
Bédard, Claude; Destexhe, Alain
2009-01-01
The power spectrum of local field potentials (LFPs) has been reported to scale as the inverse of the frequency, but the origin of this 1/f noise is at present unclear. Macroscopic measurements in cortical tissue demonstrated that electric conductivity (as well as permittivity) is frequency-dependent, while other measurements failed to evidence any dependence on frequency. In this article, we propose a model of the genesis of LFPs that accounts for the above data and contradictions. Starting from first principles (Maxwell equations), we introduce a macroscopic formalism in which macroscopic measurements are naturally incorporated, and also examine different physical causes for the frequency dependence. We suggest that ionic diffusion primes over electric field effects, and is responsible for the frequency dependence. This explains the contradictory observations, and also reproduces the 1/f power spectral structure of LFPs, as well as more complex frequency scaling. Finally, we suggest a measurement method to reveal the frequency dependence of current propagation in biological tissue, and which could be used to directly test the predictions of this formalism. PMID:19348744
Badendick, Jessica; Godkin, Owen; Kohl, Benjamin; Meier, Carola; Jagielski, Michal; Huang, Zhao; Arens, Stephan; Schneider, Tobias; Schulze-Tanzil, Gundula
2016-01-01
Osteoarthritis (OA) might affect chondrocyte culture characteristics and complement expression. Therefore, this study addressed the interrelation between macroscopical and microscopical structure, complement expression, and chondrocyte culture characteristics in non-OA and OA cartilage. Femoral head cartilage samples harvested from patients with femoral neck fractures (FNFs) and OA were analyzed for macroscopical alterations using an in-house scoring system, graded histologically (Mankin score), and immunolabeled for complement regulatory proteins (CRPs) and receptors. Morphology of monolayer cultured chondrocytes isolated from a subset of samples was assessed. The macroscopical score distinguished the FNF and OA cartilage samples and correlated significantly with the histological results. Chondrocyte phenotype from FNF or OA cartilage differed. Complement receptor C5aR, CRPs CD55 and CD59, and weakly receptor C3AR were detected in the investigated FNF and OA cartilage, except for CD46, which was detected in only two of the five investigated donors. The in-house score also allows inexperienced observers to distinguish non-OA and OA cartilage for experimental purposes. PMID:27158224
Protein Structure Recognition: From Eigenvector Analysis to Structural Threading Method
Haibo Cao
2003-12-12
In this work, they try to understand the protein folding problem using pair-wise hydrophobic interaction as the dominant interaction for the protein folding process. They found a strong correlation between amino acid sequences and the corresponding native structure of the protein. Some applications of this correlation were discussed in this dissertation include the domain partition and a new structural threading method as well as the performance of this method in the CASP5 competition. In the first part, they give a brief introduction to the protein folding problem. Some essential knowledge and progress from other research groups was discussed. This part includes discussions of interactions among amino acids residues, lattice HP model, and the design ability principle. In the second part, they try to establish the correlation between amino acid sequence and the corresponding native structure of the protein. This correlation was observed in the eigenvector study of protein contact matrix. They believe the correlation is universal, thus it can be used in automatic partition of protein structures into folding domains. In the third part, they discuss a threading method based on the correlation between amino acid sequences and ominant eigenvector of the structure contact-matrix. A mathematically straightforward iteration scheme provides a self-consistent optimum global sequence-structure alignment. The computational efficiency of this method makes it possible to search whole protein structure databases for structural homology without relying on sequence similarity. The sensitivity and specificity of this method is discussed, along with a case of blind test prediction. In the appendix, they list the overall performance of this threading method in CASP5 blind test in comparison with other existing approaches.
Structural analysis of galactoarabinan from duckweed.
Yu, Li; Yu, Changjiang; Zhu, Ming; Cao, Yingping; Yang, Haiyan; Zhang, Xu; Ma, Yubin; Zhou, Gongke
2015-03-01
A highly branched galactoarabinan named DAG1 (Mw∼4.0×10(4) Da) was purified from Lemna aequinoctialis 6000 via 70% (v/v) ethanol extraction, followed by size-exclusion chromatography on Bio-Gel P2 and Superdex 75. Methylation analysis showed that DAG1 consisted of t-Araf, (1→5)-Araf, (1→2,5)-Araf, (1→3)-Galp, and (1→3,6)-Galp in a relative proportion of approximately 6:4:3:3:3, suggesting an arabinogalactan/galactoarabinan polysacchairde. With the aid of arabinan degrading enzymes, the structure of DAG1 repeating unit was further characterized by ELISA with specific monoclonal antibodies and Yariv reagent assay. Analyses indicated that the proposed repeating unit of DAG1 had a backbone composed of seven α-(1→5)-L-arabinofuranose residues where branching occurred at O-2 with either terminal arabinoses or arabinogalactan side chain. The arabinogalactan side chain was composed of six β-(1→3)-D-galactopyranose residues, half of which were ramified at O-6 with terminal arabinoses and the last galactose was terminated with arabinose.
Tunneling of a heavily damped macroscopic variable
Schwartz, D.B.
1987-01-01
The author studied the effect of damping upon fluxoid transitions in simple microfabricated circuits consisting of an inductor and small-area Josephson tunnel junctions. In order to provide an easily characterized source of damping, the tunnel junctions were fabricated with low-inductance resistive shunts across them. To keep tunneling from being suppressed to unreachably low temperatures, the samples were designed to exhibit tunneling at high temperatures in the absence of damping. This was achieved by having junction areas of approximately 0.1 ..mu../sup 2/, which pushes the characteristic time scales to over 10/sup 12/ s/sup -1/. Tunneling was unambiguously observed at 2K in the unshunted samples. The temperature where thermal activation won over tunneling in determining the escape rate was suppressed by an order of magnitude in the shunted samples, in good agreement with theoretical predictions. The predicted T/sup 2/ dependence of the exponent of the tunneling rate upon temperature was also clearly observed in the data. At temperatures where thermal activation dominates the escape-rate quantum corrections to the escape rate are predicted. Analysis of these effects upon the data is complicated by the high frequencies involved. Although the data does not constitute a clear test of these corrections, it seems clear that simple thermal activation without quantum corrections does not suffice to explain it.
Coupled structural/thermal/electromagnetic analysis/tailoring of graded composite structures
NASA Technical Reports Server (NTRS)
Mcknight, R. L.; Chen, P. C.; Dame, L. T.; Huang, H.
1992-01-01
Accomplishments are described for the first year effort of a 5-year program to develop a methodology for coupled structural/thermal/electromagnetic analysis/tailoring of graded composite structures. These accomplishments include: (1) the results of the selective literature survey; (2) 8-, 16-, and 20-noded isoparametric plate and shell elements; (3) large deformation structural analysis; (4) eigenanalysis; (5) anisotropic heat transfer analysis; and (6) anisotropic electromagnetic analysis.
The effect of macroscopic polarization on intrinsic and extrinsic thermal conductivities of AlN
NASA Astrophysics Data System (ADS)
Gedam, Vikas; Pansari, Anju; Sinha, Arvind Kumar; Sahoo, Bijay Kumar
2015-03-01
The effect of macroscopic polarization on thermal conductivity of bulk wurtzite AlN has been theoretically investigated. Our results show that macroscopic polarization modifies the phonon group velocity, Debye frequency and Debye temperature of the AlN. Using revised phonon velocity and Debye temperature, various phonon scattering rates and combined scattering rate are calculated as functions of the phonon frequency at room temperature. The intrinsic and extrinsic thermal conductivities of AlN have been estimated using these modified parameters. The theoretical analysis shows that up to a certain temperature the polarization effect acts as negative effect and reduces the intrinsic and extrinsic thermal conductivities. However, after this temperature both thermal conductivities are significantly enhanced. High phonon velocity and Debye temperature are the reason of this enhancement which happens due to the polarization effect. The revised thermal conductivities at room temperature are found to be increased by more than 20% in AlN due to macroscopic polarization phenomenon. The method we have developed can be taken into account during the simulation of heat transport in optoelectronic nitride devices to minimize the self heating processes.
Yasui, K; Hirai, T; Kato, T; Torii, A; Uesaka, K; Morimoto, T; Kodera, Y; Yamamura, Y; Kito, T; Hamajima, N
1997-01-01
OBJECTIVE: The authors defined a new macroscopic classification of liver metastases from colorectal cancer. SUMMARY BACKGROUND DATA: There were different prognostic results after the same operative procedure for liver metastases with similar background factors. METHODS: Eighty-one resected liver metastases were classified into simple nodular (SN) or confluent nodular (CN) types according to the characteristics of the cut surface of the tumor. RESULTS: The 5-year survival rates after hepatectomy were 41.7% for the SN lesions (n = 39) and 23.1% for the CN lesions (n = 42). The difference between the survival curves was statistically significant (p = 0.0307). Multivariate analysis using Cox's proportional hazards model revealed that the macroscopic type (p = 0.023), the tumor diameter (p = 0.0001), and the presence of lymph node metastases (p = 0.0016) were statistically significant independent prognostic factors. CONCLUSION: The new macroscopic classification may be valuable as a prognostic factor reflecting the biologic behavior of liver metastases. Images Figure 1. PMID:9389391
Basic Characteristics of a Macroscopic Measure for Detecting Abnormal Changes in a Multiagent System
Kinoshita, Tetsuo
2015-01-01
Multiagent application systems must deal with various changes in both the system and the system environment at runtime. Generally, such changes have undesirable negative effects on the system. To manage and control the system, it is important to observe and detect negative effects using an appropriate observation function of the system’s behavior. This paper focuses on the design of this function and proposes a new macroscopic measure with which to observe behavioral characteristics of a runtime multiagent system. The proposed measure is designed as the variance of fluctuation of a macroscopic activity factor of the whole system, based on theoretical analysis of the macroscopic behavioral model of a multiagent system. Experiments are conducted to investigate basic characteristics of the proposed measure, using a test bed system. The results of experiments show that the proposed measure reacts quickly and increases drastically in response to abnormal changes in the system. Hence, the proposed measure is considered a measure that can be used to detect undesirable changes in a multiagent system. PMID:25897499
From macroscopic yield criteria to atomic stresses in polymer glasses
MacNeill, David; Rottler, Joerg
2010-01-15
The relationship between macroscopic shear yield criteria and local stress distributions in deformed polymer glasses is investigated via molecular dynamics simulations on different scales of coarse-graining. Macroscopic shear stresses at the yield point obey a pressure-modified von Mises (pmvM) criterion for many different loading conditions and strain rates. Average local stresses in small volume elements obey the same yield criterion for volumes containing approx. 100 atoms or more. Qualitatively different behavior is observed on smaller scales: the average octahedral atomic shear stress has a simple linear relationship to hydrostatic pressure regardless of macroscopic stress state and failure mode. Local plastic events are identified through a threshold in the mean-squared nonaffine displacement and compared to the local stress state. We find that the pmvM criterion only predicts local yield events when stress and displacements are averaged over at least 100 atoms. By contrast, macroscopic shear yield criteria appear to lose their ability to predict plastic activity on the atomic scale.
A Macroscopic Analogue of the Nuclear Pairing Potential
ERIC Educational Resources Information Center
Dunlap, Richard A.
2013-01-01
A macroscopic system involving permanent magnets is used as an analogue to nucleons in a nucleus to illustrate the significance of the pairing interaction. This illustrates that the view of the total nuclear energy based only on the nucleon occupancy of the energy levels can yield erroneous results and it is only when the pairing interaction is…
From 1D to 3D - macroscopic nanowire aerogel monoliths.
Cheng, Wei; Rechberger, Felix; Niederberger, Markus
2016-08-01
Here we present a strategy to assemble one-dimensional nanostructures into a three-dimensional architecture with macroscopic size. With the assistance of centrifugation, we successfully gel ultrathin W18O49 nanowires with diameters of 1 to 2 nm and aspect ratios larger than 100 into 3D networks, which are transformed into monolithic aerogels by supercritical drying. PMID:27389477
Implementing the Deutsch-Jozsa algorithm with macroscopic ensembles
NASA Astrophysics Data System (ADS)
Semenenko, Henry; Byrnes, Tim
2016-05-01
Quantum computing implementations under consideration today typically deal with systems with microscopic degrees of freedom such as photons, ions, cold atoms, and superconducting circuits. The quantum information is stored typically in low-dimensional Hilbert spaces such as qubits, as quantum effects are strongest in such systems. It has, however, been demonstrated that quantum effects can be observed in mesoscopic and macroscopic systems, such as nanomechanical systems and gas ensembles. While few-qubit quantum information demonstrations have been performed with such macroscopic systems, a quantum algorithm showing exponential speedup over classical algorithms is yet to be shown. Here, we show that the Deutsch-Jozsa algorithm can be implemented with macroscopic ensembles. The encoding that we use avoids the detrimental effects of decoherence that normally plagues macroscopic implementations. We discuss two mapping procedures which can be chosen depending upon the constraints of the oracle and the experiment. Both methods have an exponential speedup over the classical case, and only require control of the ensembles at the level of the total spin of the ensembles. It is shown that both approaches reproduce the qubit Deutsch-Jozsa algorithm, and are robust under decoherence.
Testing macroscopic realism through high-mass interferometry
NASA Astrophysics Data System (ADS)
Emary, Clive; Cotter, J. P.; Arndt, Markus
2014-10-01
We define a quantum witness for high-mass matter-wave interferometers that allows us to test fundamental assumptions of macroscopic realism. We propose an experimental realization using absorptive laser gratings and show that such systems can strongly violate a macrorealistic quantum-witness equality. The measurement of the witness can therefore provide clear evidence of physics beyond macrorealism for macromolecules and nanoparticles.
Generation of macroscopic superposition states with small nonlinearity
Jeong, H.; Ralph, T.C.; Kim, M. S.; Ham, B.S.
2004-12-01
We suggest a scheme to generate a macroscopic superposition state ('Schroedinger cat state') of a free-propagating optical field using a beam splitter, homodyne measurement, and a very small Kerr nonlinear effect. Our scheme makes it possible to reduce considerably the required nonlinear effect to generate an optical cat state using simple and efficient optical elements.
Stereodynamics: From elementary processes to macroscopic chemical reactions
Kasai, Toshio; Che, Dock-Chil; Tsai, Po-Yu; Lin, King-Chuen; Palazzetti, Federico; Aquilanti, Vincenzo
2015-12-31
This paper aims at discussing new facets on stereodynamical behaviors in chemical reactions, i.e. the effects of molecular orientation and alignment on reactive processes. Further topics on macroscopic processes involving deviations from Arrhenius behavior in the temperature dependence of chemical reactions and chirality effects in collisions are also discussed.
From 1D to 3D - macroscopic nanowire aerogel monoliths.
Cheng, Wei; Rechberger, Felix; Niederberger, Markus
2016-08-01
Here we present a strategy to assemble one-dimensional nanostructures into a three-dimensional architecture with macroscopic size. With the assistance of centrifugation, we successfully gel ultrathin W18O49 nanowires with diameters of 1 to 2 nm and aspect ratios larger than 100 into 3D networks, which are transformed into monolithic aerogels by supercritical drying.
LEAD SORPTION ON RUTHENIUM OXIDE: A MACROSCOPIC AND SPECTROSCOPIC STUDY
The sorption and desorption of Pb on RuO2 xH2O were examined kinetically and thermodynamically via spectroscopic and macroscopic investigations. X-ray absorption spectroscopy (XAS) was employed to determine the sorption mechanism with regard to identity of nearest atomic neighbo...
Free-Vibration Analysis of Structures
NASA Technical Reports Server (NTRS)
Gupta, K. K.
1985-01-01
Improved numerical procedure more than twice as fast as previous methods. Unified numerical algorithm efficiently solves free-vibration problems of stationary or spinning structures with or without viscous or structural damping. Algorithm used to solve static problems involving multiple loads and to solve quadratic matrix eigenvalue problems associated with finite-dynamic-element structural discretization.
A macroscopic non-destructive testing system based on the cantilever-sample contact resonance
NASA Astrophysics Data System (ADS)
Fu, Ji; Lin, Lizhi; Zhou, Xilong; Li, Yingwei; Li, Faxin
2012-12-01
Detecting the inside or buried defects in materials and structures is always a challenge in the field of nondestructive testing (NDT). In this paper, enlightened by the operation principle of the contact resonance force microscopy or atomic force acoustic microscopy (AFAM), we proposed a macroscopic NDT system based on contact resonance of the cantilever-sample surface to detect the local stiffness variations in materials or structures. We fabricated a piezoelectric unimorph with the dimension typically of 150 mm × 8 mm × 2 mm to act as a macroscopic cantilever, whose flexural mode vibration was driven by a wideband power amplifier together with a signal generator. The vibration signal of the macroscopic cantilever is detected by a high sensitive strain gauge bonded on the cantilever surface which is much more stable than the laser diode sensor in AFAM, thus making it very suitable for outdoor operations. Scanning is realized by a three-dimensional motorized stage with the Z axis for pressing force setting. The whole system is controlled by a LabVIEW-based homemade software. Like the AFAM, this NDT system can also work in two modes, i.e., the single-frequency mode and the resonance-tracking mode. In the latter mode, the contact stiffness at each pixel of the sample can be obtained by using the measured contact resonance frequency and a beam dynamics model. Testing results of this NDT system on a grid structure with an opaque panel show that in both modes the prefabricated defect beneath the panel can be detected and the grid structures can be clearly "seen," which indicates the validity of this NDT system. The sensitivity of this NDT system was also examined.
Gecko toe and lamellar shear adhesion on macroscopic, engineered rough surfaces.
Gillies, Andrew G; Henry, Amy; Lin, Hauwen; Ren, Angela; Shiuan, Kevin; Fearing, Ronald S; Full, Robert J
2014-01-15
The role in adhesion of the toes and lamellae - intermediate-sized structures - found on the gecko foot remains unclear. Insight into the function of these structures can lead to a more general understanding of the hierarchical nature of the gecko adhesive system, but in particular how environmental topology may relate to gecko foot morphology. We sought to discern the mechanics of the toes and lamellae by examining gecko adhesion on controlled, macroscopically rough surfaces. We used live Tokay geckos, Gekko gecko, to observe the maximum shear force a gecko foot can attain on an engineered substrate constructed with sinusoidal patterns of varying amplitudes and wavelengths in sizes similar to the dimensions of the toes and lamellae structures (0.5 to 6 mm). We found shear adhesion was significantly decreased on surfaces that had amplitudes and wavelengths approaching the lamella length and inter-lamella spacing, losing 95% of shear adhesion over the range tested. We discovered that the toes are capable of adhering to surfaces with amplitudes much larger than their dimensions even without engaging claws, maintaining 60% of shear adhesion on surfaces with amplitudes of 3 mm. Gecko adhesion can be predicted by the ratio of the lamella dimensions to surface feature dimensions. In addition to setae, remarkable macroscopic-scale features of gecko toes and lamellae that include compliance and passive conformation are necessary to maintain contact, and consequently, generate shear adhesion on macroscopically rough surfaces. Findings on the larger scale structures in the hierarchy of gecko foot function could provide the biological inspiration to drive the design of more effective and versatile synthetic fibrillar adhesives.
Analysis and design technology for high-speed aircraft structures
NASA Technical Reports Server (NTRS)
Starnes, James H., Jr.; Camarda, Charles J.
1992-01-01
Recent high-speed aircraft structures research activities at NASA Langley Research Center are described. The following topics are covered: the development of analytical and numerical solutions to global and local thermal and structural problems, experimental verification of analysis methods, identification of failure mechanisms, and the incorporation of analysis methods into design and optimization strategies. The paper describes recent NASA Langley advances in analysis and design methods, structural and thermal concepts, and test methods.
Probabilistic structural analysis of adaptive/smart/intelligent space structures
NASA Technical Reports Server (NTRS)
Pai, Shantaram S.; Chamis, Christos C.
1991-01-01
A three-bay, space, cantilever truss is probabilistically evaluated for adaptive/smart/intelligent behavior. For each behavior, the scatter (ranges) in buckling loads, vibration frequencies, and member axial forces are probabilistically determined. Sensitivities associated with uncertainties in the structure, material and load variables that describe the truss are determined for different probabilities. The relative magnitude for these sensitivities are used to identify significant truss variables that control/classify its behavior to respond as an adaptive/smart/intelligent structure. Results show that the probabilistic buckling loads and vibration frequencies increase for each truss classification, with a substantial increase for intelligent trusses. Similarly, the probabilistic member axial forces reduce for adaptive and intelligent trusses and increase for smart trusses.
Probabilistic structural analysis of adaptive/smart/intelligent space structures
NASA Technical Reports Server (NTRS)
Pai, Shantaram S.; Chamis, Christos C.
1992-01-01
A three-bay, space, cantilever truss is probabilistically evaluated for adaptive/smart/intelligent behavior. For each behavior, the scatter (ranges) in buckling loads, vibration frequencies, and member axial forces are probabilistically determined. Sensitivities associated with uncertainties in the structure, material and load variables that describe the truss are determined for different probabilities. The relative magnitude for these sensitivities are used to identify significant truss variables that control/classify its behavior to respond as an adaptive/smart/intelligent structure. Results show that the probabilistic buckling loads and vibration frequencies increase for each truss classification, with a substantial increase for intelligent trusses. Similarly, the probabilistic member axial forces reduce for adaptive and intelligent trusses and increase for smart trusses.
Advances in Computational Stability Analysis of Composite Aerospace Structures
Degenhardt, R.; Araujo, F. C. de
2010-09-30
European aircraft industry demands for reduced development and operating costs. Structural weight reduction by exploitation of structural reserves in composite aerospace structures contributes to this aim, however, it requires accurate and experimentally validated stability analysis of real structures under realistic loading conditions. This paper presents different advances from the area of computational stability analysis of composite aerospace structures which contribute to that field. For stringer stiffened panels main results of the finished EU project COCOMAT are given. It investigated the exploitation of reserves in primary fibre composite fuselage structures through an accurate and reliable simulation of postbuckling and collapse. For unstiffened cylindrical composite shells a proposal for a new design method is presented.
ESF GROUND SUPPORT - STRUCTURAL STEEL ANALYSIS
T. Misiak
1996-06-26
The purpose and objective of this analysis are to expand the level of detail and confirm member sizes for steel sets included in the Ground Support Design Analysis, Reference 5.20. This analysis also provides bounding values and details and defines critical design attributes for alternative configurations of the steel set. One possible configuration for the steel set is presented. This analysis covers the steel set design for the Exploratory Studies Facility (ESF) entire Main Loop 25-foot diameter tunnel.
APT/LEDA RFQ and support frame structural analysis
Ellis, S.
1997-04-01
This report documents structural analysis of the Accelerator Production of Tritium Low Energy Demonstration Accelerator (APT/LEDA) Radio Frequency Quadrupole (RFQ) accelerator structure and its associated support frame. This work was conducted for the Department of Energy in support of the APT/LEDA. Structural analysis of the RFQ was performed to quantify stress levels and deflections due to both vacuum loading and gravity loading. This analysis also verified the proposed support scheme geometry and quantified interface loads. This analysis also determined the necessary stiffness and strength requirements of the RFQ support frame verifying the conceptual design geometry and allowing specification of individual frame elements. Complete structural analysis of the frame was completed subsequently. This report details structural analysis of the RFQ assembly with regard to gravity and vacuum loads only. Thermally induced stresses from the Radio Frequency (RF) surface resistance heating were not considered.
Integrated transient thermal-structural finite element analysis
NASA Technical Reports Server (NTRS)
Thornton, E. A.; Dechaumphai, P.; Wieting, A. R.; Tamma, K. K.
1981-01-01
An integrated thermal structural finite element approach for efficient coupling of transient thermal and structural analysis is presented. Integrated thermal structural rod and one dimensional axisymmetric elements considering conduction and convection are developed and used in transient thermal structural applications. The improved accuracy of the integrated approach is illustrated by comparisons with exact transient heat conduction elasticity solutions and conventional finite element thermal finite element structural analyses.
Structural dynamics: Probabilistic structural analysis methods. Program overview
NASA Technical Reports Server (NTRS)
Chamis, Christos C.; Hopkins, Dale A.
1991-01-01
A brief description is provided of the fundamental aspects of a quantification process. Progress since the last structural durability conference in 1989 is summarized. The methodology to date and that to be developed during the life of the program is presented. The uncertain factors are presented. The approach is outlined that is required to achieve component and/or system certification in the shortest possible time for affordable reliability risk. Two new elements appear in a block diagram: (1) uncertainties in human factor, and (2) uncertainties in the computer code. Research to quantify the uncertainties in the human factor was initiated and is discussed.
Advertising Agencies: An Analysis of Industry Structure.
ERIC Educational Resources Information Center
Smith, Sandra J.
Noting that advertising agencies have not been examined as a collective industry, this paper looks at the development and structure of the advertising agency industry. The first portion of the paper discusses the development of the agency. The remaining two sections deal with trends in and the structure of the industry including: (1) the growth of…
The Specific Analysis of Structural Equation Models
ERIC Educational Resources Information Center
McDonald, Roderick P.
2004-01-01
Conventional structural equation modeling fits a covariance structure implied by the equations of the model. This treatment of the model often gives misleading results because overall goodness of fit tests do not focus on the specific constraints implied by the model. An alternative treatment arising from Pearl's directed acyclic graph theory…
Crystal structure analysis of intermetallic compounds
NASA Technical Reports Server (NTRS)
Conner, R. A., Jr.; Downey, J. W.; Dwight, A. E.
1968-01-01
Study concerns crystal structures and lattice parameters for a number of new intermetallic compounds. Crystal structure data have been collected on equiatomic compounds, formed between an element of the Sc, Ti, V, or Cr group and an element of the Co or Ni group. The data, obtained by conventional methods, are presented in an easily usable tabular form.
Electromagnetic duality symmetry and helicity conservation for the macroscopic Maxwell's equations.
Fernandez-Corbaton, Ivan; Zambrana-Puyalto, Xavier; Tischler, Nora; Vidal, Xavier; Juan, Mathieu L; Molina-Terriza, Gabriel
2013-08-01
In this Letter, we show that the electromagnetic duality symmetry, broken in the microscopic Maxwell's equations by the presence of charges, can be restored for the macroscopic Maxwell's equations. The restoration of this symmetry is shown to be independent of the geometry of the problem. These results provide a tool for the study of light-matter interactions within the framework of symmetries and conservation laws. We illustrate its use by determining the helicity content of the natural modes of structures possessing spatial inversion symmetries and by elucidating the root causes for some surprising effects in the scattering off magnetic spheres. PMID:23971539
Reliability analysis applied to structural tests
NASA Technical Reports Server (NTRS)
Diamond, P.; Payne, A. O.
1972-01-01
The application of reliability theory to predict, from structural fatigue test data, the risk of failure of a structure under service conditions because its load-carrying capability is progressively reduced by the extension of a fatigue crack, is considered. The procedure is applicable to both safe-life and fail-safe structures and, for a prescribed safety level, it will enable an inspection procedure to be planned or, if inspection is not feasible, it will evaluate the life to replacement. The theory has been further developed to cope with the case of structures with initial cracks, such as can occur in modern high-strength materials which are susceptible to the formation of small flaws during the production process. The method has been applied to a structure of high-strength steel and the results are compared with those obtained by the current life estimation procedures. This has shown that the conventional methods can be unconservative in certain cases, depending on the characteristics of the structure and the design operating conditions. The suitability of the probabilistic approach to the interpretation of the results from full-scale fatigue testing of aircraft structures is discussed and the assumptions involved are examined.
Structural Configuration Systems Analysis for Advanced Aircraft Fuselage Concepts
NASA Technical Reports Server (NTRS)
Mukhopadhyay, Vivek; Welstead, Jason R.; Quinlan, Jesse R.; Guynn, Mark D.
2016-01-01
Structural configuration analysis of an advanced aircraft fuselage concept is investigated. This concept is characterized by a double-bubble section fuselage with rear mounted engines. Based on lessons learned from structural systems analysis of unconventional aircraft, high-fidelity finite-element models (FEM) are developed for evaluating structural performance of three double-bubble section configurations. Structural sizing and stress analysis are applied for design improvement and weight reduction. Among the three double-bubble configurations, the double-D cross-section fuselage design was found to have a relatively lower structural weight. The structural FEM weights of these three double-bubble fuselage section concepts are also compared with several cylindrical fuselage models. Since these fuselage concepts are different in size, shape and material, the fuselage structural FEM weights are normalized by the corresponding passenger floor area for a relative comparison. This structural systems analysis indicates that an advanced composite double-D section fuselage may have a relative structural weight ratio advantage over a conventional aluminum fuselage. Ten commercial and conceptual aircraft fuselage structural weight estimates, which are empirically derived from the corresponding maximum takeoff gross weight, are also presented and compared with the FEM- based estimates for possible correlation. A conceptual full vehicle FEM model with a double-D fuselage is also developed for preliminary structural analysis and weight estimation.
Enabling Rapid and Robust Structural Analysis During Conceptual Design
NASA Technical Reports Server (NTRS)
Eldred, Lloyd B.; Padula, Sharon L.; Li, Wu
2015-01-01
This paper describes a multi-year effort to add a structural analysis subprocess to a supersonic aircraft conceptual design process. The desired capabilities include parametric geometry, automatic finite element mesh generation, static and aeroelastic analysis, and structural sizing. The paper discusses implementation details of the new subprocess, captures lessons learned, and suggests future improvements. The subprocess quickly compares concepts and robustly handles large changes in wing or fuselage geometry. The subprocess can rank concepts with regard to their structural feasibility and can identify promising regions of the design space. The automated structural analysis subprocess is deemed robust and rapid enough to be included in multidisciplinary conceptual design and optimization studies.
A novel CFD/structural analysis of a cross parachute
LaFarge, R.A.; Nelsen, J.M.; Gwinn, K.W.
1993-12-31
A novel CFD/structural analysis was performed to predict functionality of a cross parachute under loadings near the structural limits of the parachute. The determination of parachute functionality was based on the computed structural integrity of the canopy and suspension lines. In addition to the standard aerodynamic pressure loading on the canopy, the structural analysis considered the reduction in fabric strength due to the computed aerodynamic heating. The intent was to illustrate the feasibility of such an analysis with the commercially available software PATRAN.
Finite element-finite difference thermal/structural analysis of large space truss structures
NASA Technical Reports Server (NTRS)
Warren, Andrew H.; Arelt, Joseph E.; Eskew, William F.; Rogers, Karen M.
1992-01-01
A technique of automated and efficient thermal-structural processing of truss structures that interfaces the finite element and finite difference method was developed. The thermal-structural analysis tasks include development of the thermal and structural math models, thermal analysis, development of an interface and data transfer between the models, and finally an evaluation of the thermal stresses and displacements in the structure. Consequently, the objective of the developed technique was to minimize the model development time, in order to assure an automatic transfer of data between the thermal and structural models as well as to minimize the computer resources needed for the analysis itself. The method and techniques described are illustrated on the thermal/structural analysis of the Space Station Freedom main truss.
From 1D to 3D - macroscopic nanowire aerogel monoliths
NASA Astrophysics Data System (ADS)
Cheng, Wei; Rechberger, Felix; Niederberger, Markus
2016-07-01
Here we present a strategy to assemble one-dimensional nanostructures into a three-dimensional architecture with macroscopic size. With the assistance of centrifugation, we successfully gel ultrathin W18O49 nanowires with diameters of 1 to 2 nm and aspect ratios larger than 100 into 3D networks, which are transformed into monolithic aerogels by supercritical drying.Here we present a strategy to assemble one-dimensional nanostructures into a three-dimensional architecture with macroscopic size. With the assistance of centrifugation, we successfully gel ultrathin W18O49 nanowires with diameters of 1 to 2 nm and aspect ratios larger than 100 into 3D networks, which are transformed into monolithic aerogels by supercritical drying. Electronic supplementary information (ESI) available: Experimental details, SEM and TEM images, and digital photographs. See DOI: 10.1039/c6nr04429h
Indirect measurement of interfacial melting from macroscopic ice observations
NASA Astrophysics Data System (ADS)
Saruya, Tomotaka; Kurita, Kei; Rempel, Alan W.
2014-06-01
Premelted water that is adsorbed to particle surfaces and confined to capillary regions remains in the liquid state well below the bulk melting temperature and can supply the segregated growth of ice lenses. Using macroscopic measurements of ice-lens initiation position in step-freezing experiments, we infer how the nanometer-scale thicknesses of premelted films depend on temperature depression below bulk melting. The interfacial interactions between ice, liquid, and soda-lime glass particles exhibit a power-law behavior that suggests premelting in our system is dominated by short-range electrostatic forces. Using our inferred film thicknesses as inputs to a simple force-balance model with no adjustable parameters, we obtain good quantitative agreement between numerical predictions and observed ice-lens thickness. Macroscopic observations of lensing behavior have the potential as probes of premelting behavior in other systems.
Indirect measurement of interfacial melting from macroscopic ice observations.
Saruya, Tomotaka; Kurita, Kei; Rempel, Alan W
2014-06-01
Premelted water that is adsorbed to particle surfaces and confined to capillary regions remains in the liquid state well below the bulk melting temperature and can supply the segregated growth of ice lenses. Using macroscopic measurements of ice-lens initiation position in step-freezing experiments, we infer how the nanometer-scale thicknesses of premelted films depend on temperature depression below bulk melting. The interfacial interactions between ice, liquid, and soda-lime glass particles exhibit a power-law behavior that suggests premelting in our system is dominated by short-range electrostatic forces. Using our inferred film thicknesses as inputs to a simple force-balance model with no adjustable parameters, we obtain good quantitative agreement between numerical predictions and observed ice-lens thickness. Macroscopic observations of lensing behavior have the potential as probes of premelting behavior in other systems.
Wave speeds in the macroscopic extended model for ultrarelativistic gases
Borghero, F.; Demontis, F.; Pennisi, S.
2013-11-15
Equations determining wave speeds for a model of ultrarelativistic gases are investigated. This model is already present in literature; it deals with an arbitrary number of moments and it was proposed in the context of exact macroscopic approaches in Extended Thermodynamics. We find these results: the whole system for the determination of the wave speeds can be divided into independent subsystems which are expressed by linear combinations, through scalar coefficients, of tensors all of the same order; some wave speeds, but not all of them, are expressed by square roots of rational numbers; finally, we prove that these wave speeds for the macroscopic model are the same of those furnished by the kinetic model.
Macroscopically Separated Gaps in Dimer Coverings of Aztec Rectangles
NASA Astrophysics Data System (ADS)
Ciucu, Mihai
2016-05-01
In this paper we determine the interaction of diagonal defect clusters in regions of an Aztec rectangle that scale to arbitrary points on its symmetry axis (in earlier work we treated the case when this point was the center of the scaled Aztec rectangle). We use the resulting formulas to determine the asymptotics of the correlation of defects that are macroscopically separated from one another and feel the influence of the boundary. In several of the treated situations this seems not to be accomplishable by previous methods. Our applications include the case of two long neutral strings, which turn out to interact by an analog of the Casimir force, two families of neutral doublets that turn out to interact completely independently of one another, a neutral doublet and a very long neutral string, a general collection of macroscopically separated monomer and separation defects, and the case of long strings consisting of consecutive monomers.
Has Macroscopic Superposition in Superconducting Qubits Really Been Demonstrated?
NASA Astrophysics Data System (ADS)
Kadin, Alan M.; Kaplan, Steven B.
Quantum computing depends on many qubits coupled via quantum entanglement, where each qubit must be a simultaneous superposition of two quantum states of different energies, rather than one state or the other as in classical bits. It is widely believed that observations of energy quantization and Rabi oscillations in macroscopic superconducting circuits prove that these are proper qubits with quantum superposition. But is this really the only interpretration? We propose a novel paradigm for macroscopic quantum systems, in which energies are quantized (with photon-mediated transitions), but the quantized states are realistic objects without superposition. For example, a circuit could make a transition from one quantized value of flux to another, but would never have both at the same time. We further suggest a superconducting circuit that can put this proposal to a test. Without quantum superposition, most of the potential benefit of quantum computing would be lost.
Macroscopic view of light pressure on a continuous medium
NASA Astrophysics Data System (ADS)
Gorkunov, M. V.; Kondratov, A. V.
2013-07-01
The ambiguity of the macroscopic description of light pressure on a continuous medium originates from the uncertainty of dividing the energy-momentum tensor of electromagnetically excited matter into a material and field parts or, equivalently, the total acting force into pressure and deformation terms. We show that, although there exists a continuum of formally correct formulations, one can adopt the appropriate form of the macroscopic field stress tensor that allows a unified description of pressure during elementary light-matter interactions, such as reflection, refraction, absorption, and nonlinear conversion. The derived simple expressions for the pressure force are compatible with the polariton momentum ℏk. The corresponding relation for the electromagnetic momentum density generalizes Rytov's definition for right-handed and left-handed frequency dispersive media.
Crystallization and Structure Analysis of Membrane Proteins
NASA Astrophysics Data System (ADS)
Newman, Richard
In recent years, there has been great progress in the determination of high-resolution three-dimensional (3D) structures of membrane proteins. The first major breakthrough came with the crystallization (1) and X-ray crystallography (2,3) of the bacterial photosynthetic reaction center (see refs. 4 and 5 for reviews). The structure of another, entirely different membrane protein, the bacterial outer membrane porin from Rhodobacter capsulatus, has now been determined by X-ray crystallography (6). Recent results by electron crystallography of two-dimensional (2D) crystals have been most encouraging. The high-resolution 3D structure of bacteriorhodopsin (7) plant light-harvesting complex (8) and projection maps of several other membrane proteins at similar resolutions (9-11) have been obtained by this technique. Electron crystallography seems particularly appropriate for membrane proteins that are prone to form 2D crystals, and it is hoped that many more structures will be determined in this way.
Solid Propellant Grain Structural Integrity Analysis
NASA Technical Reports Server (NTRS)
1973-01-01
The structural properties of solid propellant rocket grains were studied to determine the propellant resistance to stresses. Grain geometry, thermal properties, mechanical properties, and failure modes are discussed along with design criteria and recommended practices.
Structural analysis of kasugamycin inhibition of translation
Schuwirth, Barbara S; Day, J Michael; Hau, Cathy W; Janssen, Gary R; Dahlberg, Albert E; Cate, Jamie H Doudna; Vila-Sanjurjo, Antón
2008-01-01
The prokaryotic ribosome is an important target of antibiotic action. We determined the X-ray structure of the aminoglycoside kasugamycin (Ksg) in complex with the Escherichia coli 70S ribosome at 3.5-Å resolution. The structure reveals that the drug binds within the messenger RNA channel of the 30S subunit between the universally conserved G926 and A794 nucleotides in 16S ribosomal RNA, which are sites of Ksg resistance. To our surprise, Ksg resistance mutations do not inhibit binding of the drug to the ribosome. The present structural and biochemical results indicate that inhibition by Ksg and Ksg resistance are closely linked to the structure of the mRNA at the junction of the peptidyl-tRNA and exit-tRNA sites (P and E sites). PMID:16998486
Analysis of structures under fire conditions
NASA Astrophysics Data System (ADS)
Kajaste-Rudnitski, Juri
The prospect of the application of a standard finite element method program to study the ability of a structure to withstand fire is studied. The objective of using a finite element method program for structure fire resistance evaluation is to compliment, if not to substitute, the expensive fire tests of the natural size structural elements. Besides, an existing measurement technique provides limited scope of data: the temperature and displacement at the reference points of the structure. Furthermore, the simulation of the real fire situation is rather difficult in the laboratory conditions. The numerical model of the concrete type of material with temperature dependent properties is studied. The standard finite element method program ABAQUS chosen for this purpose enables users to create their own subroutines and insert them into the main program.
Computer applications for engineering/structural analysis. Revision 1
Zaslawsky, M.; Samaddar, S.K.
1991-12-31
Analysts and organizations have a tendency to lock themselves into specific codes with the obvious consequences of not addressing the real problem and thus reaching the wrong conclusion. This paper discusses the role of the analyst in selecting computer codes. The participation and support of a computation division in modifying the source program, configuration management, and pre- and post-processing of codes are among the subjects discussed. Specific examples illustrating the computer code selection process are described in the following problem areas: soil structure interaction, structural analysis of nuclear reactors, analysis of waste tanks where fluid structure interaction is important, analysis of equipment, structure-structure interaction, analysis of the operation of the superconductor supercollider which includes friction and transient temperature, and 3D analysis of the 10-meter telescope being built in Hawaii. Validation and verification of computer codes and their impact on the selection process are also discussed.
Probabilistic structural analysis algorithm development for computational efficiency
NASA Technical Reports Server (NTRS)
Wu, Y.-T.
1991-01-01
The PSAM (Probabilistic Structural Analysis Methods) program is developing a probabilistic structural risk assessment capability for the SSME components. An advanced probabilistic structural analysis software system, NESSUS (Numerical Evaluation of Stochastic Structures Under Stress), is being developed as part of the PSAM effort to accurately simulate stochastic structures operating under severe random loading conditions. One of the challenges in developing the NESSUS system is the development of the probabilistic algorithms that provide both efficiency and accuracy. The main probability algorithms developed and implemented in the NESSUS system are efficient, but approximate in nature. In the last six years, the algorithms have improved very significantly.
Optical detection of the Casimir force between macroscopic objects.
Petrov, Victor; Petrov, Mikhail; Bryksin, Valeriy; Petter, Juergen; Tschudi, Theo
2006-11-01
We report the optical detection of mechanical deformation of a macroscopic object induced by the Casimir force. An adaptive holographic interferometer based on a photorefractive BaTiO3:Co crystal was used to measure periodical nonlinear deformations of a thin pellicle caused by an oscillating Casimir force. A reasonable agreement between the experimental and calculated values of the first and second harmonics of the Casimir force oscillations has been obtained. PMID:17041670
Fast Analytical Methods for Macroscopic Electrostatic Models in Biomolecular Simulations*
Xu, Zhenli; Cai, Wei
2013-01-01
We review recent developments of fast analytical methods for macroscopic electrostatic calculations in biological applications, including the Poisson–Boltzmann (PB) and the generalized Born models for electrostatic solvation energy. The focus is on analytical approaches for hybrid solvation models, especially the image charge method for a spherical cavity, and also the generalized Born theory as an approximation to the PB model. This review places much emphasis on the mathematical details behind these methods. PMID:23745011
Macroscopic phase separation in high-temperature superconductors
Wen, Hai-Hu
2000-01-01
High-temperature superconductivity is recovered by introducing extra holes to the Cu-O planes, which initially are insulating with antiferromagnetism. In this paper I present data to show the macroscopic electronic phase separation that is caused by either mobile doping or electronic instability in the overdoped region. My results clearly demonstrate that the electronic inhomogeneity is probably a general feature of high-temperature superconductors. PMID:11027323
Macroscopic vacuum effects in an inhomogeneous and nonstationary electromagnetic field
Gal'tsov, D.V.; Nikitina, N.S.
1983-04-01
Macroscopic effects of vacuum polarization by a strong nonuniform and nonstationary fields, which are kinematically forbidden in the case of a uniform magnetic field, are considered. Calculations are perfomed for the deflection of a light beam in the field of a magnetic dipole, for the production of photon pairs by an inclined rotator, and for doubling and modulation of the frequency in scattering of low-frequency electromagnetic waves by the magnetic field of an inclined rotator.
Fission barriers in a macroscopic-microscopic model
Dobrowolski, A.; Pomorski, K.; Bartel, J.
2007-02-15
In the framework of the macroscopic-microscopic model, this study investigates fission barriers in the region of actinide nuclei. A very effective four-dimensional shape parametrization for fissioning nuclei is proposed. Taking, in particular, the left-right mass asymmetric and nonaxial shapes into account is demonstrated to have a substantial effect on fission barrier heights. The influence of proton versus neutron deformation differences on the potential energy landscape of fissioning nuclei is also discussed.
Optimal asymptotic learning rate: Macroscopic versus microscopic dynamics
NASA Astrophysics Data System (ADS)
Leen, Todd K.; Schottky, Bernhard; Saad, David
1999-01-01
We investigate the asymptotic dynamics of on-line learning for neural networks, and provide an exact solution to the network dynamics at late times under various annealing schedules. The dynamics is solved using two different frameworks: the master equation and order parameter dynamics, which concentrate on microscopic and macroscopic parameters, respectively. The two approaches provide complementary descriptions of the dynamics. Optimal annealing rates and the corresponding prefactors are derived for soft committee machine networks with hidden layers of arbitrary size.
Macroscopic superposition of ultracold atoms with orbital degrees of freedom
Garcia-March, M. A.; Carr, L. D.; Dounas-Frazer, D. R.
2011-04-15
We introduce higher dimensions into the problem of Bose-Einstein condensates in a double-well potential, taking into account orbital angular momentum. We completely characterize the eigenstates of this system, delineating new regimes via both analytical high-order perturbation theory and numerical exact diagonalization. Among these regimes are mixed Josephson- and Fock-like behavior, crossings in both excited and ground states, and shadows of macroscopic superposition states.
Quantitatively Resolving Multivalent Interactions on Macroscopic Scale Using Force Spectroscopy
Hu, Qiongzheng; Yang, Haopeng; Wang, Yuhong; Xu, Shoujun
2016-01-01
Multivalent interactions remain difficult to be characterized and consequently controlled, particularly on a macroscopic scale. Using force-induced remnant magnetization spectroscopy (FIRMS), we have resolved the single-, double-, and triple- biotin—streptavidin interactions, multivalent DNA interactions and CXCL12-CXCR4 interactions, on millimetre-scale surfaces. Our results establish FIRMS as a viable method for systematic resolution and controlled formation of multivalent interactions. PMID:26864087
Optomechanical entanglement of a macroscopic oscillator by quantum feedback
NASA Astrophysics Data System (ADS)
Wu, E.; Li, Fengzhi; Zhang, Xuefeng; Ma, Yonghong
2016-07-01
We propose a scheme to generate the case of macroscopic entanglement in the optomechanical system, which consist of Fabry-Perot cavity and a mechanical oscillator by applying a homodyne-mediated quantum feedback. We explore the effect of feedback on the entanglement in vacuum and coherent state, respectively. The results show that the introduction of quantum feedback can increase the entanglement effectively between the cavity mode and the oscillator mode.
Measurement-Induced Macroscopic Superposition States in Cavity Optomechanics
NASA Astrophysics Data System (ADS)
Hoff, Ulrich B.; Kollath-Bönig, Johann; Neergaard-Nielsen, Jonas S.; Andersen, Ulrik L.
2016-09-01
A novel protocol for generating quantum superpositions of macroscopically distinct states of a bulk mechanical oscillator is proposed, compatible with existing optomechanical devices operating in the bad-cavity limit. By combining a pulsed optomechanical quantum nondemolition (QND) interaction with nonclassical optical resources and measurement-induced feedback, the need for strong single-photon coupling is avoided. We outline a three-pulse sequence of QND interactions encompassing squeezing-enhanced cooling by measurement, state preparation, and tomography.
Anisotropic magnetothermopower in ferromagnetic thin films grown on macroscopic substrates
NASA Astrophysics Data System (ADS)
Jayathilaka, P. B.; Belyea, D. D.; Fawcett, T. J.; Miller, Casey W.
2015-05-01
We report observing the anisotropic magnetothermopower in a variety of ferromagnetic thin films grown on macroscopic substrates. These measurements were enabled by eliminating spurious signals related to the Anomalous Nernst Effect by butt-mounting the sample to the heat source and sink, and appropriate positioning of electrical contacts to avoid unwanted thermal gradients. This protocol enabled detailed measurements of the magnetothermopower in the transverse and longitudinal configurations. This may enable Spin Seebeck Effect studies in the in-plane geometry.
Macroscopic Equations Governing Noisy Spiking Neuronal Populations with Linear Synapses
Galtier, Mathieu N.; Touboul, Jonathan
2013-01-01
Deriving tractable reduced equations of biological neural networks capturing the macroscopic dynamics of sub-populations of neurons has been a longstanding problem in computational neuroscience. In this paper, we propose a reduction of large-scale multi-population stochastic networks based on the mean-field theory. We derive, for a wide class of spiking neuron models, a system of differential equations of the type of the usual Wilson-Cowan systems describing the macroscopic activity of populations, under the assumption that synaptic integration is linear with random coefficients. Our reduction involves one unknown function, the effective non-linearity of the network of populations, which can be analytically determined in simple cases, and numerically computed in general. This function depends on the underlying properties of the cells, and in particular the noise level. Appropriate parameters and functions involved in the reduction are given for different models of neurons: McKean, Fitzhugh-Nagumo and Hodgkin-Huxley models. Simulations of the reduced model show a precise agreement with the macroscopic dynamics of the networks for the first two models. PMID:24236067
The mirrors model: macroscopic diffusion without noise or chaos
NASA Astrophysics Data System (ADS)
Chiffaudel, Yann; Lefevere, Raphaël
2016-03-01
Before stating our main result, we first clarify through classical examples the status of the laws of macroscopic physics as laws of large numbers. We next consider the mirrors model in a finite d-dimensional domain and connected to particles reservoirs at fixed chemical potentials. The dynamics is purely deterministic and non-ergodic but takes place in a random environment. We study the macroscopic current of particles in the stationary regime. We show first that when the size of the system goes to infinity, the behaviour of the stationary current of particles is governed by the proportion of orbits crossing the system. This allows us to formulate a necessary and sufficient condition on the distribution of the set of orbits that ensures the validity of Fick’s law. Using this approach, we show that Fick’s law relating the stationary macroscopic current of particles to the concentration difference holds in three dimensions and above. The negative correlations between crossing orbits play a key role in the argument.
Macroscopic states induced in superconducting media by a transport current under flux creep
NASA Astrophysics Data System (ADS)
Romanovskii, V. R.
2016-08-01
The physical features of the formation of macroscopic states of superconducting composites consisting of a superconductor and a coating under flux creep are discussed. It is demonstrated that there exist characteristic electric field strengths depending on the properties of the superconductor, cooling conditions, and characteristics of the stabilizing coating, which affect the intensity of the E-I characteristics of the superconducting composites. Analysis shows that the measurements of the critical properties of superconductors can be accompanied by a nonuniform electric field distribution over the composite cross section and high stable superheating of the superconductor, which do not lead to superconductivity breaking.
Structural Analysis of the NCSX Vacuum Vessel
Fred Dahlgren; Art Brooks; Paul Goranson; Mike Cole; Peter Titus
2004-09-28
The NCSX (National Compact Stellarator Experiment) vacuum vessel has a rather unique shape being very closely coupled topologically to the three-fold stellarator symmetry of the plasma it contains. This shape does not permit the use of the common forms of pressure vessel analysis and necessitates the reliance on finite element analysis. The current paper describes the NCSX vacuum vessel stress analysis including external pressure, thermal, and electro-magnetic loading from internal plasma disruptions and bakeout temperatures of up to 400 degrees centigrade. Buckling and dynamic loading conditions are also considered.
NASA Technical Reports Server (NTRS)
Arnold, S. M.; Saleeb, A. F.; Wilt, T. E.; Trowbridge, D.
2000-01-01
Extensive research efforts have been made over the years on the phenomenological representations of constitutive material behavior in the inelastic analysis and life assessment of structures composed of advanced monolithic and composite (CMC, MMC, and PMC) materials. Recently, emphasis has been placed on concurrently addressing three important and related areas of constitutive and degradation modeling; i.e. (i) mathematical formulation, (ii) algorithmic developments for the updating (integrating) of external (e.g. stress) and internal state variable, as well as (iii) parameter estimation for the characterization of the specific model. This concurrent perspective has resulted in; i) the formulation of a fully-associative viscoelastoplastic model (GVIPS), (ii) development of an efficient implicit integration and it's associative, symmetric, consistent tangent stiffness matrix algorithm for integration of the underlying rate flow/evolutionary equations, and iii) a robust, stand-alone, Constitutive Material Parameter Estimator (COMPARE) for automatically characterizing the various time-dependent, nonlinear, material models. Furthermore, to provide a robust multi-scale framework for the deformation and life analysis of structures composed of composite materials, NASA Glenn has aggressively pursued the development of a sufficiently general, accurate, and efficient micromechanics approach known as the generalized method of cells (GMC). This work has resulted in the development of MAC/GMC, a stand-alone micromechanics analysis tool that can easily and accurately design/analyze multiphase (composite) materials subjected to complex histories. MAC/GMC admits generalized, physically based, deformation and damage models for each constituent and provides "closed-form" expressions for the macroscopic composite response in terms of the properties, size, shape, distribution, and response of the individual constituents or phases that comprise the material. Consequently, MAC/GMC can
Terahertz wave spectrum analysis of microstrip structure
NASA Astrophysics Data System (ADS)
Song, Mei-jing; Li, Jiu-sheng
2011-11-01
Terahertz wave is a kind of electromagnetic wave ranging from 0.1~10THz, between microwave and infrared, which occupies a special place in the electromagnetic spectrum. Terahertz radiation has a strong penetration for many media materials and nonpolar substance, for example, dielectric material, plastic, paper carton and cloth. In recent years, researchers around the world have paid great attention on terahertz technology, such as safety inspection, chemical biology, medical diagnosis and terahertz wave imaging, etc. Transmission properties of two-dimensional metal microstrip structures in the terahertz regime are presented and tested. Resonant terahertz transmission was demonstrated in four different arrays of subwavelength microstrip structure patterned on semiconductor. The effects of microstrip microstrip structure shape were investigated by using terahertz time-domain spectroscopy system. The resonant terahertz transmission has center frequency of 2.05 THz, transmission of 70%.
Terahertz wave spectrum analysis of microstrip structure
NASA Astrophysics Data System (ADS)
Song, Mei-jing; Li, Jiu-sheng
2012-03-01
Terahertz wave is a kind of electromagnetic wave ranging from 0.1~10THz, between microwave and infrared, which occupies a special place in the electromagnetic spectrum. Terahertz radiation has a strong penetration for many media materials and nonpolar substance, for example, dielectric material, plastic, paper carton and cloth. In recent years, researchers around the world have paid great attention on terahertz technology, such as safety inspection, chemical biology, medical diagnosis and terahertz wave imaging, etc. Transmission properties of two-dimensional metal microstrip structures in the terahertz regime are presented and tested. Resonant terahertz transmission was demonstrated in four different arrays of subwavelength microstrip structure patterned on semiconductor. The effects of microstrip microstrip structure shape were investigated by using terahertz time-domain spectroscopy system. The resonant terahertz transmission has center frequency of 2.05 THz, transmission of 70%.
Condensed Antenna Structural Models for Dynamics Analysis
NASA Technical Reports Server (NTRS)
Levy, R.
1985-01-01
Condensed degree-of-freedom models are compared with large degree-of-freedom finite-element models of a representative antenna-tipping and alidade structure, for both locked and free-rotor configurations. It is shown that: (1) the effective-mass models accurately reproduce the lower-mode natural frequencies of the finite element model; (2) frequency responses for the two types of models are in agreement up to at least 16 rad/s for specific points; and (3) transient responses computed for the same points are in good agreement. It is concluded that the effective-mass model, which best represents the five lower modes of the finite-element model, is a sufficient representation of the structure for future incorporation with a total servo control structure dynamic simulation.
Total-System Approach To Design And Analysis Of Structures
NASA Technical Reports Server (NTRS)
Verderaime, V.
1995-01-01
Paper presents overview and study of, and comprehensive approach to, multidisciplinary engineering design and analysis of structures. Emphasizes issues related to design of semistatic structures in environments in which spacecraft launched, underlying concepts applicable to other structures within unique terrestrial, marine, or flight environments. Purpose of study to understand interactions among traditionally separate engineering design disciplines with view toward optimizing not only structure but also overall design process.
Structural Analysis Using NX Nastran 9.0
NASA Technical Reports Server (NTRS)
Rolewicz, Benjamin M.
2014-01-01
NX Nastran is a powerful Finite Element Analysis (FEA) software package used to solve linear and non-linear models for structural and thermal systems. The software, which consists of both a solver and user interface, breaks down analysis into four files, each of which are important to the end results of the analysis. The software offers capabilities for a variety of types of analysis, and also contains a respectable modeling program. Over the course of ten weeks, I was trained to effectively implement NX Nastran into structural analysis and refinement for parts of two missions at NASA's Kennedy Space Center, the Restore mission and the Orion mission.
An endoscope for simultaneous macroscopic navigation and microscopic inspection of luminal sidewalls
NASA Astrophysics Data System (ADS)
Leavesley, Silas; Sturgis, Jennifer; Robinson, J. Paul
2008-02-01
Endoscopic techniques are commonly used for esophageal and gastrointestinal screening. In this process, atypical regions are identified by gross visual and morphological changes. These regions are then biopsied for pathological confirmation prior to determining treatment. In an effort to increase the sensitivity of endoscopic screening, many groups have performed work in developing microscopic endoscopes capable of inspecting tissues on a cellular level. These microscopic endoscopes are generally implemented as either a stand-alone fiber or through the working channel of a traditional endoscope, and are oriented in a manner similar to traditional flexible endoscopes, imaging the region directly ahead of the endoscope with a wide-angle lens. However, this may not be the optimum configuration for microscopic inspection of luminal sidewalls. We present a novel optical configuration for an endoscope that can simultaneously function as a traditional forward-viewing macroscopic endoscope and as a sidewall-viewing microscopic endoscope. With the first prototype, we have realized a water-emersion microscopic that is capable of imaging tissues on a single-cell level. In addition, microscopic side-port configuration enables efficient mapping of the luminal wall. Utilizing simultaneous macroscopic and microscopic imaging, we are developing software for image registration and analysis that will enable localization of microscopic features within a macroscopic frame of reference. Through a combination of microscopic sidewall imaging and software for image analysis, we aim to provide the clinician with the equivalent of an in vivo biopsy, increasing screening effectiveness and decreasing discomfort and costs related to performing multiple biopsies of suspected regions.
Cognitive Diagnostic Analysis Using Hierarchically Structured Skills
ERIC Educational Resources Information Center
Su, Yu-Lan
2013-01-01
This dissertation proposes two modified cognitive diagnostic models (CDMs), the deterministic, inputs, noisy, "and" gate with hierarchy (DINA-H) model and the deterministic, inputs, noisy, "or" gate with hierarchy (DINO-H) model. Both models incorporate the hierarchical structures of the cognitive skills in the model estimation…
RNA structural analysis by evolving SHAPE chemistry.
Spitale, Robert C; Flynn, Ryan A; Torre, Eduardo A; Kool, Eric T; Chang, Howard Y
2014-01-01
RNA is central to the flow of biological information. From transcription to splicing, RNA localization, translation, and decay, RNA is intimately involved in regulating every step of the gene expression program, and is thus essential for health and understanding disease. RNA has the unique ability to base-pair with itself and other nucleic acids to form complex structures. Hence the information content in RNA is not simply its linear sequence of bases, but is also encoded in complex folding of RNA molecules. A general chemical functionality that all RNAs have is a 2'-hydroxyl group in the ribose ring, and the reactivity of the 2'-hydroxyl in RNA is gated by local nucleotide flexibility. In other words, the 2'-hydroxyl is reactive at single-stranded and conformationally flexible positions but is unreactive at nucleotides constrained by base-pairing. Recent efforts have been focused on developing reagents that modify RNA as a function of RNA 2' hydroxyl group reactivity. Such RNA structure probing techniques can be read out by primer extension in experiments termed RNA SHAPE (selective 2'- hydroxyl acylation and primer extension). Herein, we describe the efforts devoted to the design and utilization of SHAPE probes for characterizing RNA structure. We also describe current technological advances that are being applied to utilize SHAPE chemistry with deep sequencing to probe many RNAs in parallel. The merging of chemistry with genomics is sure to open the door to genome-wide exploration of RNA structure and function.
Theses "Discussion" Sections: A Structural Move Analysis
ERIC Educational Resources Information Center
Nodoushan, Mohammad Ali Salmani; Khakbaz, Nafiseh
2011-01-01
The current study aimed at finding the probable differences between the move structure of Iranian MA graduates' thesis discussion subgenres and those of their non-Iranian counterparts, on the one hand, and those of journal paper authors, on the other. It also aimed at identifying the moves that are considered obligatory, conventional, or optional…
An Efficient Analysis Methodology for Fluted-Core Composite Structures
NASA Technical Reports Server (NTRS)
Oremont, Leonard; Schultz, Marc R.
2012-01-01
The primary loading condition in launch-vehicle barrel sections is axial compression, and it is therefore important to understand the compression behavior of any structures, structural concepts, and materials considered in launch-vehicle designs. This understanding will necessarily come from a combination of test and analysis. However, certain potentially beneficial structures and structural concepts do not lend themselves to commonly used simplified analysis methods, and therefore innovative analysis methodologies must be developed if these structures and structural concepts are to be considered. This paper discusses such an analysis technique for the fluted-core sandwich composite structural concept. The presented technique is based on commercially available finite-element codes, and uses shell elements to capture behavior that would normally require solid elements to capture the detailed mechanical response of the structure. The shell thicknesses and offsets using this analysis technique are parameterized, and the parameters are adjusted through a heuristic procedure until this model matches the mechanical behavior of a more detailed shell-and-solid model. Additionally, the detailed shell-and-solid model can be strategically placed in a larger, global shell-only model to capture important local behavior. Comparisons between shell-only models, experiments, and more detailed shell-and-solid models show excellent agreement. The discussed analysis methodology, though only discussed in the context of fluted-core composites, is widely applicable to other concepts.
Large-scale structural analysis: The structural analyst, the CSM Testbed and the NAS System
NASA Technical Reports Server (NTRS)
Knight, Norman F., Jr.; Mccleary, Susan L.; Macy, Steven C.; Aminpour, Mohammad A.
1989-01-01
The Computational Structural Mechanics (CSM) activity is developing advanced structural analysis and computational methods that exploit high-performance computers. Methods are developed in the framework of the CSM testbed software system and applied to representative complex structural analysis problems from the aerospace industry. An overview of the CSM testbed methods development environment is presented and some numerical methods developed on a CRAY-2 are described. Selected application studies performed on the NAS CRAY-2 are also summarized.
Application of structured analysis to a telerobotic system
NASA Technical Reports Server (NTRS)
Dashman, Eric; Mclin, David; Harrison, F. W.; Soloway, Donald; Young, Steven
1990-01-01
The analysis and evaluation of a multiple arm telerobotic research and demonstration system developed by the NASA Intelligent Systems Research Laboratory (ISRL) is described. Structured analysis techniques were used to develop a detailed requirements model of an existing telerobotic testbed. Performance models generated during this process were used to further evaluate the total system. A commercial CASE tool called Teamwork was used to carry out the structured analysis and development of the functional requirements model. A structured analysis and design process using the ISRL telerobotic system as a model is described. Evaluation of this system focused on the identification of bottlenecks in this implementation. The results demonstrate that the use of structured methods and analysis tools can give useful performance information early in a design cycle. This information can be used to ensure that the proposed system meets its design requirements before it is built.
Experiences with a preliminary NICE/SPAR structural analysis system
NASA Technical Reports Server (NTRS)
Lotts, C. G.; Greene, W. H.
1985-01-01
Development of a new structural analysis system based on the original SPAR finite element code and the NICE system is described. The system is denoted NICE/SPAR. NICE was designed at Lockheed Palo Alto Research Laboratory and contains data management utilities, a command language interpreter, and a command language definition for integrating engineering computational modules. SPAR is a system of programs used for finite element structural analysis developed for NASA by Engineering Information Systems, Inc. It includes many complementary structural analysis and utility functions which communicate through a common database. The work on NICE/SPAR was motivated by requirements for a highly modular and flexible structural analysis system to use as a tool in carrying out research in computational methods and exploring new computer hardware. Analysis examples are presented which demonstrate the benefits gained from a combination of the NICE command language with the SPAR computational modules.
Fabrication and Characterization of Three-Dimensional Macroscopic All-Carbon Scaffolds
Lalwani, Gaurav; Kwaczala, Andrea Trinward; Kanakia, Shruti; Patel, Sunny C.; Judex, Stefan; Sitharaman, Balaji
2012-01-01
We report a simple method to fabricate macroscopic, 3-D, free standing, all-carbon scaffolds (porous structures) using multiwalled carbon nanotubes (MWCNTs) as the starting materials. The scaffolds prepared by radical initiated thermal crosslinking, and annealing of MWCNTs possess macroscale interconnected pores, robust structural integrity, stability, and conductivity. The porosity of the three-dimensional structure can be controlled by varying the amount of radical initiator, thereby allowing the design of porous scaffolds tailored towards specific potential applications. This method also allows the fabrication of 3-D scaffolds using other carbon nanomaterials such as single-walled carbon nanotubes, fullerenes, and graphene indicating that it could be used as a versatile method for 3-D assembly of carbon nanostructures with pi bond networks. PMID:23436939
Complex eigenvalue analysis of rotating structures
NASA Technical Reports Server (NTRS)
Patel, J. S.; Seltzer, S. M.
1972-01-01
A FORTRAN subroutine to NASTRAN which constructs coriolis and centripetal acceleration matrices, and a centrifugal load vector due to spin about a selected point or about the mass center of the structure is discussed. The rigid translational degrees of freedom can be removed by using a transformation matrix T and its explicitly given inverse. These matrices are generated in the subroutine and their explicit expressions are given.
Truncated Moment Analysis of Nucleon Structure Functions
A. Psaker; W. Melnitchouk; M. E. Christy; C. E. Keppel
2007-11-16
We employ a novel new approach using "truncated" moments, or integrals of structure functions over restricted regions of x, to study local quark-hadron duality, and the degree to which individual resonance regions are dominated by leading twists. Because truncated moments obey the same Q^2 evolution equations as the leading twist parton distributions, this approach makes possible for the first time a description of resonance region data and the phenomenon of quark-hadron duality directly from QCD.
Probabilistic Computer Analysis for Rapid Evaluation of Structures.
2007-03-29
P-CARES 2.0.0, Probabilistic Computer Analysis for Rapid Evaluation of Structures, was developed for NRC staff use to determine the validity and accuracy of the analysis methods used by various utilities for structural safety evaluations of nuclear power plants. P-CARES provides the capability to effectively evaluate the probabilistic seismic response using simplified soil and structural models and to quickly check the validity and/or accuracy of the SSI data received from applicants and licensees. The code ismore » organized in a modular format with the basic modules of the system performing static, seismic, and nonlinear analysis.« less
Probabilistic Computer Analysis for Rapid Evaluation of Structures.
XU, JIM
2007-03-29
P-CARES 2.0.0, Probabilistic Computer Analysis for Rapid Evaluation of Structures, was developed for NRC staff use to determine the validity and accuracy of the analysis methods used by various utilities for structural safety evaluations of nuclear power plants. P-CARES provides the capability to effectively evaluate the probabilistic seismic response using simplified soil and structural models and to quickly check the validity and/or accuracy of the SSI data received from applicants and licensees. The code is organized in a modular format with the basic modules of the system performing static, seismic, and nonlinear analysis.
Acoustic Emission Analysis of Prestressed Concrete Structures
NASA Astrophysics Data System (ADS)
Elfergani, H. A.; Pullin, R.; Holford, K. M.
2011-07-01
Corrosion is a substantial problem in numerous structures and in particular corrosion is very serious in reinforced and prestressed concrete and must, in certain applications, be given special consideration because failure may result in loss of life and high financial cost. Furthermore corrosion cannot only be considered a long term problem with many studies reporting failure of bridges and concrete pipes due to corrosion within a short period after they were constructed. The concrete pipes which transport water are examples of structures that have suffered from corrosion; for example, the pipes of The Great Man-Made River Project of Libya. Five pipe failures due to corrosion have occurred since their installation. The main reason for the damage is corrosion of prestressed wires in the pipes due to the attack of chloride ions from the surrounding soil. Detection of the corrosion in initial stages has been very important to avoid other failures and the interruption of water flow. Even though most non-destructive methods which are used in the project are able to detect wire breaks, they cannot detect the presence of corrosion. Hence in areas where no excavation has been completed, areas of serious damage can go undetected. Therefore, the major problem which faces engineers is to find the best way to detect the corrosion and prevent the pipes from deteriorating. This paper reports on the use of the Acoustic Emission (AE) technique to detect the early stages of corrosion prior to deterioration of concrete structures.
Nonlinear dynamic analysis of quasi-symmetric anisotropic structures
NASA Technical Reports Server (NTRS)
Noor, Ahmed K.; Peters, Jeanne M.
1987-01-01
An efficient computational method for the nonlinear dynamic analysis of quasi-symmetric anisotropic structures is proposed. The application of mixed models simplifies the analytical development and improves the accuracy of the response predictions, and operator splitting allows the reduction of the analysis model of the quasi-symmetric structure to that of the corresponding symmetric structure. The preconditoned conjugate gradient provides a stable and effective technique for generating the unsymmetric response of the structure as the sum of a symmetrized response plus correction modes. The effectiveness of the strategy is demonstrated with the example of a laminated anisotropic shallow shell of quadrilateral planform subjected to uniform normal loading.
Modal analysis of kagome-lattice structures
NASA Astrophysics Data System (ADS)
Perez, H.; Blakley, S.; Zheltikov, A. M.
2015-05-01
The first few lowest order circularly symmetric electromagnetic eigenmodes of a full kagome lattice are compared to those of a kagome lattice with a hexagonal defect. This analysis offers important insights into the physics behind the waveguiding properties of hollow-core fibers with a kagome-lattice cladding.
Analysis of lossy composite terminating structures
NASA Technical Reports Server (NTRS)
Andre, R.; Dominek, A.; Munk, J.; Wang, N.
1991-01-01
A finite element solution and computer code for the electromagnetic scattering of inhomogeneous penetrable bodies is presented. The application for the code is for the analysis and design of leading and trailing edge terminations when conducting and nonconducting materials are used. Examples of simple triangular shaped terminations are also presented.
NASA Astrophysics Data System (ADS)
Thadison, Felicia Culver
Explanations of chemical phenomena rely on understanding the behavior of submicroscopic particles. Because this level is "invisible," it is described using symbols such as models, diagrams and equations. For this reason, students often view chemistry as a "difficult" subject. The laboratory offers a unique opportunity for the students to experience chemistry macroscopically as well as symbolically. The purpose of this investigation was to determine how chemistry lab students explained chemical phenomenon on the macroscopic, submicroscopic, and representational/symbolic level. The participants were undergraduate students enrolled in an introductory level general chemistry lab course. Students' background information (gender, the number of previous chemistry courses), scores on final exams, and final average for the course were collected. Johnstone's triangle of representation guided the design and implementation of this study. A semi-structured interview was also conducted to bring out student explanations. The questionnaires required students to draw a molecule of water, complete acid base reaction equations, represent, submicroscopically, the four stages of an acid-base titration, and provide definitions of various terms. Students were able represent the submicroscopic level of water. Students were not able to represent the submicroscopic level of the reaction between an acid and a base. Students were able to represent the macroscopic level of an acid base reaction. Students were able to symbolically represent the reaction of an acid and a base. These findings indicate that students can use all three levels of chemical representation. However, students showed an inability to connect the levels in relation to acid-base chemistry. There was no relationship between a student's ability to use the levels and his or her final score in the course.
Template matching method for the analysis of interstellar cloud structure
NASA Astrophysics Data System (ADS)
Juvela, M.
2016-09-01
Context. The structure of interstellar medium can be characterised at large scales in terms of its global statistics (e.g. power spectra) and at small scales by the properties of individual cores. Interest has been increasing in structures at intermediate scales, resulting in a number of methods being developed for the analysis of filamentary structures. Aims: We describe the application of the generic template-matching (TM) method to the analysis of maps. Our aim is to show that it provides a fast and still relatively robust way to identify elongated structures or other image features. Methods: We present the implementation of a TM algorithm for map analysis. The results are compared against rolling Hough transform (RHT), one of the methods previously used to identify filamentary structures. We illustrate the method by applying it to Herschel surface brightness data. Results: The performance of the TM method is found to be comparable to that of RHT but TM appears to be more robust regarding the input parameters, for example, those related to the selected spatial scales. Small modifications of TM enable one to target structures at different size and intensity levels. In addition to elongated features, we demonstrate the possibility of using TM to also identify other types of structures. Conclusions: The TM method is a viable tool for data quality control, exploratory data analysis, and even quantitative analysis of structures in image data.
Structural dynamic analysis of a ball joint
NASA Astrophysics Data System (ADS)
Hwang, Seok-Cheol; Lee, Kwon-Hee
2012-11-01
Ball joint is a rotating and swiveling element that is typically installed at the interface between two parts. In an automobile, the ball joint is the component that connects the control arms to the steering knuckle. The ball joint can also be installed in linkage systems for motion control applications. This paper describes the simulation strategy for a ball joint analysis, considering manufacturing process. Its manufacturing process can be divided into plugging and spinning. Then, the interested responses is selected as the stress distribution generated between its ball and bearing. In this paper, a commercial code of NX DAFUL using an implicit integration method is introduced to calculate the response. In addition, the gap analysis is performed to investigate the fitness, focusing on the response of the displacement of a ball stud. Also, the optimum design is suggested through case studies.
Parallel processing in finite element structural analysis
NASA Technical Reports Server (NTRS)
Noor, Ahmed K.
1987-01-01
A brief review is made of the fundamental concepts and basic issues of parallel processing. Discussion focuses on parallel numerical algorithms, performance evaluation of machines and algorithms, and parallelism in finite element computations. A computational strategy is proposed for maximizing the degree of parallelism at different levels of the finite element analysis process including: 1) formulation level (through the use of mixed finite element models); 2) analysis level (through additive decomposition of the different arrays in the governing equations into the contributions to a symmetrized response plus correction terms); 3) numerical algorithm level (through the use of operator splitting techniques and application of iterative processes); and 4) implementation level (through the effective combination of vectorization, multitasking and microtasking, whenever available).
Structural analysis of hierarchically organized zeolites
NASA Astrophysics Data System (ADS)
Mitchell, Sharon; Pinar, Ana B.; Kenvin, Jeffrey; Crivelli, Paolo; Kärger, Jörg; Pérez-Ramírez, Javier
2015-10-01
Advances in materials synthesis bring about many opportunities for technological applications, but are often accompanied by unprecedented complexity. This is clearly illustrated by the case of hierarchically organized zeolite catalysts, a class of crystalline microporous solids that has been revolutionized by the engineering of multilevel pore architectures, which combine unique chemical functionality with efficient molecular transport. Three key attributes, the crystal, the pore and the active site structure, can be expected to dominate the design process. This review examines the adequacy of the palette of techniques applied to characterize these distinguishing features and their catalytic impact.
Structural analysis of suerconducting bending magnets
Meuser, R.B.
1980-05-01
Mechanical stresses, displacements, and the effects of displacements upon aberrations of the magnetic field in the aperture have been calculated for a class of superconducting bending-magnet configurations. The analytical model employed for the coil is one in which elements are free to slide without restraint upon each other, and upon the surrounding structure. Coil configurations considered range from an idealized one in which the current density varies as cosine theta to more realistic ones consisting of regions of uniform current density. With few exceptions, the results for the more realistic coils closely match those of the cos theta coil.
Analysis of dispersion characteristics of phononic structures
Parkhomenko, D. A. Kolenov, S. A.; Grigoruk, V. I.; Movchan, N. N.
2011-05-15
A general theory for calculating the dispersion of bulk acoustic waves in 3D and 2D phononic crystals made of anisotropic materials is presented, which is based on the plane-wave expansion method. Two approaches to separating acoustic modes in the dispersion diagrams are proposed. The pattern of the acoustic field distribution is studied as depending on the wavevector direction for various types of modes. Degeneracy of acoustic modes in directions different from the axes of symmetry of the phononic crystal is demonstrated. Possibilities of the proposed method are illustrated by the application to 3D and 2D silicon-based phononic crystal structures.
Structural analysis of hierarchically organized zeolites
Mitchell, Sharon; Pinar, Ana B.; Kenvin, Jeffrey; Crivelli, Paolo; Kärger, Jörg; Pérez-Ramírez, Javier
2015-01-01
Advances in materials synthesis bring about many opportunities for technological applications, but are often accompanied by unprecedented complexity. This is clearly illustrated by the case of hierarchically organized zeolite catalysts, a class of crystalline microporous solids that has been revolutionized by the engineering of multilevel pore architectures, which combine unique chemical functionality with efficient molecular transport. Three key attributes, the crystal, the pore and the active site structure, can be expected to dominate the design process. This review examines the adequacy of the palette of techniques applied to characterize these distinguishing features and their catalytic impact. PMID:26482337
Molecular and structural analysis of viscoelastic properties
NASA Astrophysics Data System (ADS)
Yapp, Rebecca D.; Kalyanam, Sureshkumar; Insana, Michael F.
2007-03-01
Elasticity imaging is emerging as an important tool for breast cancer detection and monitoring of treatment. Viscoelastic image contrast in breast lesions is generated by disease specific processes that modify the molecular structure of connective tissues. We showed previously that gelatin hydrogels exhibit mechanical behavior similar to native collagen found in breast tissue and therefore are suitable as phantoms for elasticity imaging. This paper summarizes our study of the viscoelastic properties of hydrogels designed to discover molecular-scale sources of elasticity image contrast.
Scale relativity theory and integrative systems biology: 2. Macroscopic quantum-type mechanics.
Nottale, Laurent; Auffray, Charles
2008-05-01
In these two companion papers, we provide an overview and a brief history of the multiple roots, current developments and recent advances of integrative systems biology and identify multiscale integration as its grand challenge. Then we introduce the fundamental principles and the successive steps that have been followed in the construction of the scale relativity theory, which aims at describing the effects of a non-differentiable and fractal (i.e., explicitly scale dependent) geometry of space-time. The first paper of this series was devoted, in this new framework, to the construction from first principles of scale laws of increasing complexity, and to the discussion of some tentative applications of these laws to biological systems. In this second review and perspective paper, we describe the effects induced by the internal fractal structures of trajectories on motion in standard space. Their main consequence is the transformation of classical dynamics into a generalized, quantum-like self-organized dynamics. A Schrödinger-type equation is derived as an integral of the geodesic equation in a fractal space. We then indicate how gauge fields can be constructed from a geometric re-interpretation of gauge transformations as scale transformations in fractal space-time. Finally, we introduce a new tentative development of the theory, in which quantum laws would hold also in scale space, introducing complexergy as a measure of organizational complexity. Initial possible applications of this extended framework to the processes of morphogenesis and the emergence of prokaryotic and eukaryotic cellular structures are discussed. Having founded elements of the evolutionary, developmental, biochemical and cellular theories on the first principles of scale relativity theory, we introduce proposals for the construction of an integrative theory of life and for the design and implementation of novel macroscopic quantum-type experiments and devices, and discuss their potential
Structure analysis on synthetic emerald crystals
NASA Astrophysics Data System (ADS)
Lee, Pei-Lun; Lee, Jiann-Shing; Huang, Eugene; Liao, Ju-Hsiou
2013-05-01
Single crystals of emerald synthesized by means of the flux method were adopted for crystallographic analyses. Emerald crystals with a wide range of Cr3+-doping content up to 3.16 wt% Cr2O3 were examined by X-ray single crystal diffraction refinement method. The crystal structures of the emerald crystals were refined to R 1 (all data) of 0.019-0.024 and w R 2 (all data) of 0.061-0.073. When Cr3+ substitutes for Al3+, the main adjustment takes place in the Al-octahedron and Be-tetrahedron. The effect of substitution of Cr3+ for Al3+ in the beryl structure results in progressively lengthening of the Al-O distance, while the length of the other bonds remains nearly unchanged. The substitution of Cr3+ for Al3+ may have caused the expansion of a axis, while keeping the c axis unchanged in the emerald lattice. As a consequence, the Al-O-Si and Al-O-Be bonding angles are found to decrease, while the angle of Si-O-Be increases as the Al-O distance increases during the Cr replacement.
Analysis of hyperfine structure in photoassociation spectra
NASA Astrophysics Data System (ADS)
Bergeman, T.
2008-05-01
The low Doppler width in photoassociation spectra from cold atoms makes hyperfine structure clearly visible, especially with heavier alkali atoms. Recently the focus has been on photoassociation to weakly bound dimers [1,2]. However there are also useful data on somewhat more deeply bound levels [2] for which a different coupling scheme is appropriate. Following [3], we use a F = J + I representation, and develop a transformation between this and the usual case e representation which applies at asymptotically large internuclear distance. We hope to model and assign hyperfine structure in φ = 1 states, using appropriate ground and excited state wavefunctions. To obtain eigenvalues from very large DVR matrices, we use a ``stepwise diagonalization'' procedure, which appears to be more efficient than standard sparse matrix methods. [1] E. Tiesinga et al. PRA 71, 052703 (2005); K. M. Jones et al, RMP 78, 483 (2006). [2] Data on Rb2 from J. Qi, D. Wang, Y. Huang, H. Pechkis, E. Eyler, P. Gould, W. C. Stwalley, C. C. Tsai and D.J. Heinzen; Data on RbCs from A. J. Kerman, J. M. Sage, S. Sainis and D. DeMille. [3] B. Gao, PRA 54, 2022 (1996).
Nonlinear transient analysis of joint dominated structures
NASA Technical Reports Server (NTRS)
Chapman, J. M.; Shaw, F. H.; Russell, W. C.
1987-01-01
A residual force technique is presented that can perform the transient analyses of large, flexible, and joint dominated structures. The technique permits substantial size reduction in the number of degrees of freedom describing the nonlinear structural models and can account for such nonlinear joint phenomena as free-play and hysteresis. In general, joints can have arbitrary force-state map representations but these are used in the form of residual force maps. One essential feature of the technique is to replace the arbitrary force-state maps describing the nonlinear joints with residual force maps describing the truss links. The main advantage of this replacement is that the incrementally small relative displacements and velocities across a joint are not monitored directly thereby avoiding numerical difficulties. Instead, very small and 'soft' residual forces are defined giving a numerically attractive form for the equations of motion and thereby permitting numerically stable integration algorithms. The technique was successfully applied to the transient analyses of a large 58 bay, 60 meter truss having nonlinear joints. A method to perform link testing is also presented.
Structural and quantitative analysis of Equisetum alkaloids.
Cramer, Luise; Ernst, Ludger; Lubienski, Marcus; Papke, Uli; Schiebel, Hans-Martin; Jerz, Gerold; Beuerle, Till
2015-08-01
Equisetum palustre L. is known for its toxicity for livestock. Several studies in the past addressed the isolation and identification of the responsible alkaloids. So far, palustrine (1) and N(5)-formylpalustrine (2) are known alkaloids of E. palustre. A HPLC-ESI-MS/MS method in combination with simple sample work-up was developed to identify and quantitate Equisetum alkaloids. Besides the two known alkaloids six related alkaloids were detected in different Equisetum samples. The structure of the alkaloid palustridiene (3) was derived by comprehensive 1D and 2D NMR experiments. N(5)-Acetylpalustrine (4) was also thoroughly characterized by NMR for the first time. The structure of N(5)-formylpalustridiene (5) is proposed based on mass spectrometry results. Twenty-two E. palustre samples were screened by a HPLC-ESI-MS/MS method after development of a simple sample work-up and in most cases the set of all eight alkaloids were detected in all parts of the plant. A high variability of the alkaloid content and distribution was found depending on plant organ, plant origin and season ranging from 88 to 597mg/kg dried weight. However, palustrine (1) and the alkaloid palustridiene (3) always represented the main alkaloids. For the first time, a comprehensive identification, quantitation and distribution of Equisetum alkaloids was achieved.
Mixed time integration methods for transient thermal analysis of structures
NASA Technical Reports Server (NTRS)
Liu, W. K.
1982-01-01
The computational methods used to predict and optimize the thermal structural behavior of aerospace vehicle structures are reviewed. In general, two classes of algorithms, implicit and explicit, are used in transient thermal analysis of structures. Each of these two methods has its own merits. Due to the different time scales of the mechanical and thermal responses, the selection of a time integration method can be a different yet critical factor in the efficient solution of such problems. Therefore mixed time integration methods for transient thermal analysis of structures are being developed. The computer implementation aspects and numerical evaluation of these mixed time implicit-explicit algorithms in thermal analysis of structures are presented. A computationally useful method of estimating the critical time step for linear quadrilateral element is also given. Numerical tests confirm the stability criterion and accuracy characteristics of the methods. The superiority of these mixed time methods to the fully implicit method or the fully explicit method is also demonstrated.
Maximum Entropy Methods as the Bridge Between Microscopic and Macroscopic Theory
NASA Astrophysics Data System (ADS)
Taylor, Jamie M.
2016-09-01
This paper is concerned with an investigation into a function of macroscopic variables known as the singular potential, building on previous work by Ball and Majumdar. The singular potential is a function of the admissible statistical averages of probability distributions on a state space, defined so that it corresponds to the maximum possible entropy given known observed statistical averages, although non-classical entropy-like objective functions will also be considered. First the set of admissible moments must be established, and under the conditions presented in this work the set is open, bounded and convex allowing a description in terms of supporting hyperplanes, which provides estimates on the development of singularities for related probability distributions. Under appropriate conditions it is shown that the singular potential is strictly convex, as differentiable as the microscopic entropy, and blows up uniformly as the macroscopic variable tends to the boundary of the set of admissible moments. Applications of the singular potential are then discussed, and particular consideration will be given to certain free-energy functionals typical in mean-field theory, demonstrating an equivalence between certain microscopic and macroscopic free-energy functionals. This allows statements about L^1-local minimisers of Onsager's free energy to be obtained which cannot be given by two-sided variations, and overcomes the need to ensure local minimisers are bounded away from zero and +∞ before taking L^∞ variations. The analysis also permits the definition of a dual order parameter for which Onsager's free energy allows an explicit representation. Also, the difficulties in approximating the singular potential by everywhere defined functions, in particular by polynomial functions, are addressed, with examples demonstrating the failure of the Taylor approximation to preserve relevant shape properties of the singular potential.
Maximum Entropy Methods as the Bridge Between Microscopic and Macroscopic Theory
NASA Astrophysics Data System (ADS)
Taylor, Jamie M.
2016-07-01
This paper is concerned with an investigation into a function of macroscopic variables known as the singular potential, building on previous work by Ball and Majumdar. The singular potential is a function of the admissible statistical averages of probability distributions on a state space, defined so that it corresponds to the maximum possible entropy given known observed statistical averages, although non-classical entropy-like objective functions will also be considered. First the set of admissible moments must be established, and under the conditions presented in this work the set is open, bounded and convex allowing a description in terms of supporting hyperplanes, which provides estimates on the development of singularities for related probability distributions. Under appropriate conditions it is shown that the singular potential is strictly convex, as differentiable as the microscopic entropy, and blows up uniformly as the macroscopic variable tends to the boundary of the set of admissible moments. Applications of the singular potential are then discussed, and particular consideration will be given to certain free-energy functionals typical in mean-field theory, demonstrating an equivalence between certain microscopic and macroscopic free-energy functionals. This allows statements about L^1 -local minimisers of Onsager's free energy to be obtained which cannot be given by two-sided variations, and overcomes the need to ensure local minimisers are bounded away from zero and +∞ before taking L^∞ variations. The analysis also permits the definition of a dual order parameter for which Onsager's free energy allows an explicit representation. Also, the difficulties in approximating the singular potential by everywhere defined functions, in particular by polynomial functions, are addressed, with examples demonstrating the failure of the Taylor approximation to preserve relevant shape properties of the singular potential.
NASA Astrophysics Data System (ADS)
Chanin, Rochelle Jennifer
The purpose of this study was to investigate whether CHEM-PHYS 102 students' understanding of physical and chemical change was enhanced by experiencing an activity in which they interacted with visualizations of physical and chemical change at the macroscopic and particulate levels. Students were administered a pre test prior to instruction on physical and chemical change. Mid semester they participated in one of three visualization treatments, and at the end of the semester a post test was administered. The research questioned explored in this study were: 1) Does participation in the PCAct affect students' ability to correctly distinguish physical and chemical changes as measured by the pre and post PCA? 2) When students are specifically cued with particulate level visualizations is there an increase in the frequency of particulate level explanations? 3) Is the explanation perspective of the student consistent with the stimulus? And 4) How many particulate visualizations on the PCAct must students experience to increase the frequency of particulate level explanations on the post PCA? This study specifically analyzes the visualization treatment, physical and chemical change activity (PCAct), and uses scores on students' performance on the post test to measure gains. Methods of analysis included independent and dependent samples
Hekmat, Mohamad Hamed; Mirzaei, Masoud
2015-01-01
In the present research, we tried to improve the performance of the lattice Boltzmann (LB) -based adjoint approach by utilizing the mesoscopic inherent of the LB method. In this regard, two macroscopic discrete adjoint (MADA) and microscopic discrete adjoint (MIDA) approaches are used to answer the following two challenging questions. Is it possible to extend the concept of the macroscopic and microscopic variables of the flow field to the corresponding adjoint ones? Further, similar to the conservative laws in the LB method, is it possible to find the comparable conservation equations in the adjoint approach? If so, then a definite framework, similar to that used in the flow solution by the LB method, can be employed in the flow sensitivity analysis by the MIDA approach. This achievement can decrease the implementation cost and coding efforts of the MIDA method in complicated sensitivity analysis problems. First, the MADA and MIDA equations are extracted based on the LB method using the duality viewpoint. Meanwhile, using an elementary case, inverse design of a two-dimensional unsteady Poiseuille flow in a periodic channel with constant body forces, the procedure of analytical evaluation of the adjoint variables is described. The numerical results show that similar correlations between the distribution functions can be seen between the corresponding adjoint ones. Besides, the results are promising, emphasizing the flow field adjoint variables can be evaluated via the adjoint distribution functions. Finally, the adjoint conservative laws are introduced. PMID:25679735
Failure Analysis and Mechanisms of Failure of Fibrous Composite Structures
NASA Technical Reports Server (NTRS)
Noor, A. K. (Compiler); Shuart, M. J. (Compiler); Starnes, J. H., Jr. (Compiler); Williams, J. G. (Compiler)
1983-01-01
The state of the art of failure analysis and current design practices, especially as applied to the use of fibrous composite materials in aircraft structures is discussed. Deficiencies in these technologies are identified, as are directions for future research.
Progressive Failure Analysis Methodology for Laminated Composite Structures
NASA Technical Reports Server (NTRS)
Sleight, David W.
1999-01-01
A progressive failure analysis method has been developed for predicting the failure of laminated composite structures under geometrically nonlinear deformations. The progressive failure analysis uses C(exp 1) shell elements based on classical lamination theory to calculate the in-plane stresses. Several failure criteria, including the maximum strain criterion, Hashin's criterion, and Christensen's criterion, are used to predict the failure mechanisms and several options are available to degrade the material properties after failures. The progressive failure analysis method is implemented in the COMET finite element analysis code and can predict the damage and response of laminated composite structures from initial loading to final failure. The different failure criteria and material degradation methods are compared and assessed by performing analyses of several laminated composite structures. Results from the progressive failure method indicate good correlation with the existing test data except in structural applications where interlaminar stresses are important which may cause failure mechanisms such as debonding or delaminations.
Applications of Mass Spectrometry to Structural Analysis of Marine Oligosaccharides
Lang, Yinzhi; Zhao, Xia; Liu, Lili; Yu, Guangli
2014-01-01
Marine oligosaccharides have attracted increasing attention recently in developing potential drugs and biomaterials for their particular physical and chemical properties. However, the composition and sequence analysis of marine oligosaccharides are very challenging for their structural complexity and heterogeneity. Mass spectrometry (MS) has become an important technique for carbohydrate analysis by providing more detailed structural information, including molecular mass, sugar constituent, sequence, inter-residue linkage position and substitution pattern. This paper provides an overview of the structural analysis based on MS approaches in marine oligosaccharides, which are derived from some biologically important marine polysaccharides, including agaran, carrageenan, alginate, sulfated fucan, chitosan, glycosaminoglycan (GAG) and GAG-like polysaccharides. Applications of electrospray ionization mass spectrometry (ESI-MS) are mainly presented and the general applications of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) are also outlined. Some technical challenges in the structural analysis of marine oligosaccharides by MS have also been pointed out. PMID:24983643
Sensitivity analysis of discrete structural systems: A survey
NASA Technical Reports Server (NTRS)
Adelman, H. M.; Haftka, R. T.
1984-01-01
Methods for calculating sensitivity derivatives for discrete structural systems are surveyed, primarily covering literature published during the past two decades. Methods are described for calculating derivatives of static displacements and stresses, eigenvalues and eigenvectors, transient structural response, and derivatives of optimum structural designs with respect to problem parameters. The survey is focused on publications addressed to structural analysis, but also includes a number of methods developed in nonstructural fields such as electronics, controls, and physical chemistry which are directly applicable to structural problems. Most notable among the nonstructural-based methods are the adjoint variable technique from control theory, and the Green's function and FAST methods from physical chemistry.
Statistical energy analysis of complex structures, phase 2
NASA Technical Reports Server (NTRS)
Trudell, R. W.; Yano, L. I.
1980-01-01
A method for estimating the structural vibration properties of complex systems in high frequency environments was investigated. The structure analyzed was the Materials Experiment Assembly, (MEA), which is a portion of the OST-2A payload for the space transportation system. Statistical energy analysis (SEA) techniques were used to model the structure and predict the structural element response to acoustic excitation. A comparison of the intial response predictions and measured acoustic test data is presented. The conclusions indicate that: the SEA predicted the response of primary structure to acoustic excitation over a wide range of frequencies; and the contribution of mechanically induced random vibration to the total MEA is not significant.
Integrated transient thermal-structural finite element analysis
NASA Technical Reports Server (NTRS)
Thornton, E. A.; Decahaumphai, P.; Tamma, K. K.; Wieting, A. R.
1981-01-01
An integrated thermal-structural finite element approach for efficient coupling of transient thermal and structural analysis is presented. New integrated thermal-structural rod and one dimensional axisymmetric elements considering conduction and convection are developed and used in transient thermal-structural applications. The improved accuracy of the integrated approach is illustrated by comparisons with exact transient heat conduction-elasticity solutions and conventional finite element thermal-finite element structural analyses. Results indicate that the approach offers significant potential for further development with other elements.
Reliability analysis of structures under periodic proof tests in service
NASA Technical Reports Server (NTRS)
Yang, J.-N.
1976-01-01
A reliability analysis of structures subjected to random service loads and periodic proof tests treats gust loads and maneuver loads as random processes. Crack initiation, crack propagation, and strength degradation are treated as the fatigue process. The time to fatigue crack initiation and ultimate strength are random variables. Residual strength decreases during crack propagation, so that failure rate increases with time. When a structure fails under periodic proof testing, a new structure is built and proof-tested. The probability of structural failure in service is derived from treatment of all the random variables, strength degradations, service loads, proof tests, and the renewal of failed structures. Some numerical examples are worked out.
Macroscopic noncontextuality as a principle for almost-quantum correlations
NASA Astrophysics Data System (ADS)
Henson, Joe; Sainz, Ana Belén
2015-04-01
Quantum mechanics allows only certain sets of experimental results (or "probabilistic models") for Bell-type quantum nonlocality experiments. A derivation of this set from simple physical or information theoretic principles would represent an important step forward in our understanding of quantum mechanics, and this problem has been intensely investigated in recent years. "Macroscopic locality," which requires the recovery of locality in the limit of large numbers of trials, is one of several principles discussed in the literature that place a bound on the set of quantum probabilistic models. A similar question can also be asked about probabilistic models for the more general class of quantum contextuality experiments. Here, we extend the macroscopic locality principle to this more general setting, using the hypergraph approach of Acín, Fritz, Leverrier, and Sainz [Comm. Math. Phys. 334(2), 533-628 (2015), 10.1007/s00220-014-2260-1], which provides a framework to study both phenomena of nonlocality and contextuality in a unified manner. We find that the set of probabilistic models allowed by our macroscopic noncontextuality principle is equivalent to an important and previously studied set in this formalism, which is slightly larger than the quantum set. In the particular case of Bell scenarios, this set is equivalent to the set of "almost-quantum" models, which is of particular interest since the latter was recently shown to satisfy all but one of the principles that have been proposed to bound quantum probabilistic models, without being implied by any of them (or even their conjunction). Our condition is the first characterization of the almost-quantum set from a simple physical principle.
Macroscopic polarization in crystalline dielectrics: the geometric phase approach
NASA Astrophysics Data System (ADS)
Resta, Raffaele
1994-07-01
The macroscopic electric polarization of a crystal is often defined as the dipole of a unit cell. In fact, such a dipole moment is ill defined, and the above definition is incorrect. Looking more closely, the quantity generally measured is differential polarization, defined with respect to a "reference state" of the same material. Such differential polarizations include either derivatives of the polarization (dielectric permittivity, Born effective charges, piezoelectricity, pyroelectricity) or finite differences (ferroelectricity). On the theoretical side, the differential concept is basic as well. Owing to continuity, a polarization difference is equivalent to a macroscopic current, which is directly accessible to the theory as a bulk property. Polarization is a quantum phenomenon and cannot be treated with a classical model, particularly whenever delocalized valence electrons are present in the dielectric. In a quantum picture, the current is basically a property of the phase of the wave functions, as opposed to the charge, which is a property of their modulus. An elegant and complete theory has recently been developed by King-Smith and Vanderbilt, in which the polarization difference between any two crystal states-in a null electric field-takes the form of a geometric quantum phase. The author gives a comprehensive account of this theory, which is relevant for dealing with transverse-optic phonons, piezoelectricity, and ferroelectricity. Its relation to the established concepts of linear-response theory is also discussed. Within the geometric phase approach, the relevant polarization difference occurs as the circuit integral of a Berry connection (or "vector potential"), while the corresponding curvature (or "magnetic field") provides the macroscopic linear response.
Analysis of Smart Composite Structures Including Debonding
NASA Technical Reports Server (NTRS)
Chattopadhyay, Aditi; Seeley, Charles E.
1997-01-01
Smart composite structures with distributed sensors and actuators have the capability to actively respond to a changing environment while offering significant weight savings and additional passive controllability through ply tailoring. Piezoelectric sensing and actuation of composite laminates is the most promising concept due to the static and dynamic control capabilities. Essential to the implementation of these smart composites are the development of accurate and efficient modeling techniques and experimental validation. This research addresses each of these important topics. A refined higher order theory is developed to model composite structures with surface bonded or embedded piezoelectric transducers. These transducers are used as both sensors and actuators for closed loop control. The theory accurately captures the transverse shear deformation through the thickness of the smart composite laminate while satisfying stress free boundary conditions on the free surfaces. The theory is extended to include the effect of debonding at the actuator-laminate interface. The developed analytical model is implemented using the finite element method utilizing an induced strain approach for computational efficiency. This allows general laminate geometries and boundary conditions to be analyzed. The state space control equations are developed to allow flexibility in the design of the control system. Circuit concepts are also discussed. Static and dynamic results of smart composite structures, obtained using the higher order theory, are correlated with available analytical data. Comparisons, including debonded laminates, are also made with a general purpose finite element code and available experimental data. Overall, very good agreement is observed. Convergence of the finite element implementation of the higher order theory is shown with exact solutions. Additional results demonstrate the utility of the developed theory to study piezoelectric actuation of composite
An expert system for integrated structural analysis and design optimization for aerospace structures
NASA Technical Reports Server (NTRS)
1992-01-01
The results of a research study on the development of an expert system for integrated structural analysis and design optimization is presented. An Object Representation Language (ORL) was developed first in conjunction with a rule-based system. This ORL/AI shell was then used to develop expert systems to provide assistance with a variety of structural analysis and design optimization tasks, in conjunction with procedural modules for finite element structural analysis and design optimization. The main goal of the research study was to provide expertise, judgment, and reasoning capabilities in the aerospace structural design process. This will allow engineers performing structural analysis and design, even without extensive experience in the field, to develop error-free, efficient and reliable structural designs very rapidly and cost-effectively. This would not only improve the productivity of design engineers and analysts, but also significantly reduce time to completion of structural design. An extensive literature survey in the field of structural analysis, design optimization, artificial intelligence, and database management systems and their application to the structural design process was first performed. A feasibility study was then performed, and the architecture and the conceptual design for the integrated 'intelligent' structural analysis and design optimization software was then developed. An Object Representation Language (ORL), in conjunction with a rule-based system, was then developed using C++. Such an approach would improve the expressiveness for knowledge representation (especially for structural analysis and design applications), provide ability to build very large and practical expert systems, and provide an efficient way for storing knowledge. Functional specifications for the expert systems were then developed. The ORL/AI shell was then used to develop a variety of modules of expert systems for a variety of modeling, finite element analysis, and
Entanglement of mixed macroscopic superpositions: An entangling-power study
Paternostro, M.; Kim, M. S.; Jeong, H.
2006-01-15
We investigate entanglement properties of a recently introduced class of macroscopic quantum superpositions in two-mode mixed states. One of the tools we use in order to infer the entanglement in this non-Gaussian class of states is the power to entangle a qubit system. Our study reveals features which are hidden in a standard approach to entanglement investigation based on the uncertainty principle of the quadrature variables. We briefly describe the experimental setup corresponding to our theoretical scenario and a suitable modification of the protocol which makes our proposal realizable within the current experimental capabilities.
Macroscopic traffic modeling with the finite difference method
Mughabghab, S.; Azarm, A.; Stock, D.
1996-03-15
A traffic congestion forecasting model (ATOP), developed in the present investigation, is described briefly. Several macroscopic models, based on the solution of the partial differential equation of conservation of vehicles by the finite difference method, were tested using actual traffic data. The functional form, as well as the parameters, of the equation of state which describes the relation between traffic speed and traffic density, were determined for a section of the Long Island Expressway. The Lax method and the forward difference technique were applied. The results of extensive tests showed that the Lax method, in addition to giving very good agreement with the traffic data, produces stable solutions.
Microscopic time-reversibility and macroscopic irreversibility: Still a paradox
Posch, H.A.; Dellago, Ch.; Hoover, W.G.; Kum, O. |
1995-09-13
Microscopic time reversibility and macroscopic irreversibility are a paradoxical combination. This was first observed by J. Loschmidt in 1876 and was explained, for conservative systems, by L. Boltzmann the following year. Both these features are also present in modern simulations of classic many-body systems in steady nonequilibrium states. We illustrate them here for the simplest possible models, a continuous one-dimensional model of field-driven diffusion, the so-called driven Lorentz gas or Galton Board, and an ergodic time reversible dissipative map.
Violation of smooth observable macroscopic realism in a harmonic oscillator.
Leshem, Amir; Gat, Omri
2009-08-14
We study the emergence of macrorealism in a harmonic oscillator subject to consecutive measurements of a squeezed action. We demonstrate a breakdown of dynamical realism in a wide parameter range that is maximized in a scaling limit of extreme squeezing, where it is based on measurements of smooth observables, implying that macroscopic realism is not valid in the harmonic oscillator. We propose an indirect experimental test of these predictions with entangled photons by demonstrating that local realism in a composite system implies dynamical realism in a subsystem.
Macroscopic Test of the Aharonov-Bohm Effect
Caprez, Adam; Barwick, Brett; Batelaan, Herman
2007-11-23
The Aharonov-Bohm (AB) effect is a purely quantum mechanical effect. The original (classified as type-I) AB-phase shift exists in experimental conditions where the electromagnetic fields and forces are zero. It is the absence of forces that makes the AB effect entirely quantum mechanical. Although the AB-phase shift has been demonstrated unambiguously, the absence of forces in type-I AB effects has never been shown. Here, we report the observation of the absence of time delays associated with forces of the magnitude needed to explain the AB-phase shift for a macroscopic system.
Single-atom quantum control of macroscopic mechanical oscillators
NASA Astrophysics Data System (ADS)
Bariani, F.; Otterbach, J.; Tan, Huatang; Meystre, P.
2014-01-01
We investigate a hybrid electromechanical system consisting of a pair of charged macroscopic mechanical oscillators coupled to a small ensemble of Rydberg atoms. The resonant dipole-dipole coupling between an internal atomic Rydberg transition and the mechanics allows cooling to its motional ground state with a single atom despite the considerable mass imbalance between the two subsystems. We show that the rich electronic spectrum of Rydberg atoms, combined with their high degree of optical control, paves the way towards implementing various quantum-control protocols for the mechanical oscillators.
Implementation of efficient sensitivity analysis for optimization of large structures
NASA Technical Reports Server (NTRS)
Umaretiya, J. R.; Kamil, H.
1990-01-01
The paper presents the theoretical bases and implementation techniques of sensitivity analyses for efficient structural optimization of large structures, based on finite element static and dynamic analysis methods. The sensitivity analyses have been implemented in conjunction with two methods for optimization, namely, the Mathematical Programming and Optimality Criteria methods. The paper discusses the implementation of the sensitivity analysis method into our in-house software package, AutoDesign.
Pore structure analysis of American coals
Gallegos, D.P.; Smith, D.M.; Stermer, D.L.
1987-01-01
The pore structure of 19 American coals, representing a wide range of rank and geographic origin, has been studied via gas adsorption, mercury porosimetry, helium displacement and NMR spin-lattice relaxation measurements. Nitrogen adsorption at 77 K was used to determine surface area in the pore range of r/sub p/ > approx. = 1nm and carbon dioxide adsorption at 273 K was used to obtain the total surface area. Porosimetry results were complicated by inter-particle void filling, surface roughness/porosity and sample compression. By employing a range of particle sizes, information concerning the relative magnitude of these mechanisms was ascertained as a function of pressure. Spin-lattice relaxation measurements of water contained in saturated coal were used to find pore size distributions over a broad range of T/sub 1/, the spin-lattice relaxation time. Good qualitative agreement was obtained between these measurements and gas adsorption/condensation results. 13 refs., 3 figs., 1 tab.
NASA Astrophysics Data System (ADS)
Lu, Peizhen
the 98% RH sample. However, HD zone shrinkage in both samples eventually slowed. Finally, we analyze this problem beginning with two-particle neck growth. We utilize Arzt's approach to connect macroscopic compact shrinkage to multiple scale microstructural variation. The connectivity of the compact is simulated through distinct element methods that specify certain structural parameters. The accuracy of this approach can be verified by measurements of high and low density zone dimensional behaviors followed by examination of the corresponding sintered state microstructures.
Sensitivity Analysis for Coupled Aero-structural Systems
NASA Technical Reports Server (NTRS)
Giunta, Anthony A.
1999-01-01
A novel method has been developed for calculating gradients of aerodynamic force and moment coefficients for an aeroelastic aircraft model. This method uses the Global Sensitivity Equations (GSE) to account for the aero-structural coupling, and a reduced-order modal analysis approach to condense the coupling bandwidth between the aerodynamic and structural models. Parallel computing is applied to reduce the computational expense of the numerous high fidelity aerodynamic analyses needed for the coupled aero-structural system. Good agreement is obtained between aerodynamic force and moment gradients computed with the GSE/modal analysis approach and the same quantities computed using brute-force, computationally expensive, finite difference approximations. A comparison between the computational expense of the GSE/modal analysis method and a pure finite difference approach is presented. These results show that the GSE/modal analysis approach is the more computationally efficient technique if sensitivity analysis is to be performed for two or more aircraft design parameters.
Microfabricated structures for integrated DNA analysis.
Burns, M A; Mastrangelo, C H; Sammarco, T S; Man, F P; Webster, J R; Johnsons, B N; Foerster, B; Jones, D; Fields, Y; Kaiser, A R; Burke, D T
1996-01-01
Photolithographic micromachining of silicon is a candidate technology for the construction of high-throughput DNA analysis devices. However, the development of complex silicon microfabricated systems has been hindered in part by the lack of a simple, versatile pumping method for integrating individual components. Here we describe a surface-tension-based pump able to move discrete nanoliter drops through enclosed channels using only local heating. This thermocapillary pump can accurately mix, measure, and divide drops by simple electronic control. In addition, we have constructed thermal-cycling chambers, gel electrophoresis channels, and radiolabeled DNA detectors that are compatible with the fabrication of thermocapillary pump channels. Since all of the components are made by conventional photolithographic techniques, they can be assembled into more complex integrated systems. The combination of pump and components into self-contained miniaturized devices may provide significant improvements in DNA analysis speed, portability, and cost. The potential of microfabricated systems lies in the low unit cost of silicon-based construction and in the efficient sample handling afforded by component integration. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:8643614
Probabilistic structural analysis methods for select space propulsion system components
NASA Technical Reports Server (NTRS)
Millwater, H. R.; Cruse, T. A.
1989-01-01
The Probabilistic Structural Analysis Methods (PSAM) project developed at the Southwest Research Institute integrates state-of-the-art structural analysis techniques with probability theory for the design and analysis of complex large-scale engineering structures. An advanced efficient software system (NESSUS) capable of performing complex probabilistic analysis has been developed. NESSUS contains a number of software components to perform probabilistic analysis of structures. These components include: an expert system, a probabilistic finite element code, a probabilistic boundary element code and a fast probability integrator. The NESSUS software system is shown. An expert system is included to capture and utilize PSAM knowledge and experience. NESSUS/EXPERT is an interactive menu-driven expert system that provides information to assist in the use of the probabilistic finite element code NESSUS/FEM and the fast probability integrator (FPI). The expert system menu structure is summarized. The NESSUS system contains a state-of-the-art nonlinear probabilistic finite element code, NESSUS/FEM, to determine the structural response and sensitivities. A broad range of analysis capabilities and an extensive element library is present.
A Family Structure Approach to the Analysis of Poverty.
ERIC Educational Resources Information Center
Stuby, Richard G.
A typological approach to the analysis of poverty, based on selected characteristics of family structure, is suggested since the family unit is a concrete or actual structure in society, and much of the research and many of the action programs of the war on poverty have implicitly invoked some concept of the family. The typology of family…
Westerlund, Fredrik; Lemke, Henrik T; Hassenkam, Tue; Simonsen, Jens B; Laursen, Bo W
2013-06-01
Highly fluorescent, discotic trioxatriangulenium dyes were aligned by simple spin-casting on substrates with friction transferred PTFE layers. The fluorescent crystalline thin films show near perfect macroscopic alignment on centimeter large areas directly from spin-casting. Gracing Incidence X-ray Diffraction (GIXD) unambiguously allowed the determination of a long-range order unit cell as well as its orientation with respect to the PTFE fibers. Further analysis of the X-ray data, in conjunction with polarized absorption spectroscopy, suggest a lamellar packing model with alternating layers of alkyl chains and ionic dyes oriented parallel to the substrate. This structure results in a highly anisotropic electrostatic potential around the cationic chromophore, causing significant shifts in energy and orientation of the optical transitions. Thus, the optical properties of the material are, to a large extent, controlled by the position of the otherwise inert PF6(-) counterions. The bright fluorescence from the films is also polarized parallel to the PTFE alignment layer. Doping of the thin films with fluorescent energy acceptor traps shows that efficient exciton migration takes place in the thin films. The excellent exciton transfer capabilities, in conjunction with the perfect alignment, might be of interest in future applications in solar energy harvesting or as thin film sensors. PMID:23627252
Reliability Analysis of Brittle, Thin Walled Structures
Jonathan A Salem and Lynn Powers
2007-02-09
One emerging application for ceramics is diesel particulate filters being used order to meet EPA regulations going into effect in 2008. Diesel particulates are known to be carcinogenic and thus need to be minimized. Current systems use filters made from ceramics such as mullite and corderite. The filters are brittle and must operate at very high temperatures during a burn out cycle used to remove the soot buildup. Thus the filters are subjected to thermal shock stresses and life time reliability analysis is required. NASA GRC has developed reliability based design methods and test methods for such applications, such as CARES/Life and American Society for Testing and Materials (ASTM) C1499 “Standard Test Method for Equibiaxial Strength of Ceramics.”
Stress analysis for structures with surface cracks
NASA Technical Reports Server (NTRS)
Bell, J. C.
1978-01-01
Two basic forms of analysis, one treating stresses around arbitrarily loaded circular cracks, the other treating stresses due to loads arbitrarily distributed on the surface of a half space, are united by a boundary-point least squares method to obtain analyses for stresses from surface cracks in places or bars. Calculations were for enough cases to show how effects from the crack vary with the depth-to-length ratio, the fractional penetration ratio, the obliquity of the load, and to some extent the fractional span ratio. The results include plots showing stress intensity factors, stress component distributions near the crack, and crack opening displacement patterns. Favorable comparisons are shown with two kinds of independent experiments, but the main method for confirming the results is by wide checking of overall satisfaction of boundary conditions, so that external confirmation is not essential. Principles involved in designing analyses which promote dependability of the results are proposed and illustrated.
Partial Wave Analysis of Coupled Photonic Structures
NASA Technical Reports Server (NTRS)
Fuller, Kirk A.; Smith, David D.; Curreri, Peter A. (Technical Monitor)
2002-01-01
The very high quality factors sustained by microcavity optical resonators are relevant to applications in wavelength filtering, routing, switching, modulation, and multiplexing/demultiplexing. Increases in the density of photonic elements require that attention be paid to how electromagnetic (EM) coupling modifies their optical properties. This is especially true when cavity resonances are involved, in which case, their characteristics may be fundamentally altered. Understanding the optical properties of microcavities that are near or in contact with photonic elements---such as other microcavities, nanostructures, couplers, and substrates---can be expected to advance our understanding of the roles that these structures may play in VLSI photonics, biosensors and similar device technologies. Wc present results from recent theoretical studies of the effects of inter- and intracavity coupling on optical resonances in compound spherical particles. Concentrically stratified spheres and bispheres constituted from homogeneous and stratified spheres are subjects of this investigation. A new formulation is introduced for the absorption of light in an arbitrary layer of a multilayered sphere, which is based on multiple reflections of the spherical partial waves of the Lorenz-Mie solution for scattering by a sphere. Absorption efficiencies, which can be used to profile cavity resonances and to infer fluorescence yields or the onset of nonlinear optical processes in the microcavities, are presented. Splitting of resonances in these multisphere systems is paid particular attention, and consequences for photonic device development and possible performance enhancements through carefully designed architectures that exploit EM coupling are considered.
Analysis of boron carbides' electronic structure
NASA Technical Reports Server (NTRS)
Howard, Iris A.; Beckel, Charles L.
1986-01-01
The electronic properties of boron-rich icosahedral clusters were studied as a means of understanding the electronic structure of the icosahedral borides such as boron carbide. A lower bound was estimated on bipolaron formation energies in B12 and B11C icosahedra, and the associated distortions. While the magnitude of the distortion associated with bipolaron formation is similar in both cases, the calculated formation energies differ greatly, formation being much more favorable on B11C icosahedra. The stable positions of a divalent atom relative to an icosahedral borane was also investigated, with the result that a stable energy minimum was found when the atom is at the center of the borane, internal to the B12 cage. If incorporation of dopant atoms into B12 cages in icosahedral boride solids is feasible, novel materials might result. In addition, the normal modes of a B12H12 cluster, of the C2B10 cage in para-carborane, and of a B12 icosahedron of reduced (D sub 3d) symmetry, such as is found in the icosahedral borides, were calculated. The nature of these vibrational modes will be important in determining, for instance, the character of the electron-lattice coupling in the borides, and in analyzing the lattice contribution to the thermal conductivity.
Coupled structural/thermal/electromagnetic analysis/tailoring of graded composite structures
NASA Technical Reports Server (NTRS)
Hartle, M. S.; Mcknight, R. L.; Huang, H.; Holt, R.
1992-01-01
Described here are the accomplishments of a 5-year program to develop a methodology for coupled structural, thermal, electromagnetic analysis tailoring of graded component structures. The capabilities developed over the course of the program are the analyzer module and the tailoring module for the modeling of graded materials. Highlighted accomplishments for the past year include the addition of a buckling analysis capability, the addition of mode shape slope calculation for flutter analysis, verification of the analysis modules using simulated components, and verification of the tailoring module.
Macroscopic tensile plasticity by scalarizating stress distribution in bulk metallic glass
Gao, Meng; Dong, Jie; Huan, Yong; Wang, Yong Tian; Wang, Wei-Hua
2016-01-01
The macroscopic tensile plasticity of bulk metallic glasses (BMGs) is highly desirable for various engineering applications. However, upon yielding, plastic deformation of BMGs is highly localized into narrow shear bands and then leads to the “work softening” behaviors and subsequently catastrophic fracture, which is the major obstacle for their structural applications. Here we report that macroscopic tensile plasticity in BMG can be obtained by designing surface pore distribution using laser surface texturing. The surface pore array by design creates a complex stress field compared to the uniaxial tensile stress field of conventional glassy specimens, and the stress field scalarization induces the unusual tensile plasticity. By systematically analyzing fracture behaviors and finite element simulation, we show that the stress field scalarization can resist the main shear band propagation and promote the formation of larger plastic zones near the pores, which undertake the homogeneous tensile plasticity. These results might give enlightenment for understanding the deformation mechanism and for further improvement of the mechanical performance of metallic glasses. PMID:26902264