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1
Bozdogan, K. B., and D. Ozturk. "Free Vibration Analysis of a Thin-Walled Beam with Shear Sensitive Material." Mathematical Problems in Engineering 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/493905.
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This paper presents a method for a free vibration analysis of a thin-walled beam of doubly asymmetric cross section filled with shear sensitive material. In the study, first of all, a dynamic transfer matrix method was obtained for planar shear flexure and torsional motion. Then, uncoupled angular frequencies were obtained by using dynamic element transfer matrices and boundary conditions. Coupled frequencies were obtained by the well-known two-dimensional approaches. At the end of the study, a sample taken from the literature was solved, and the results were evaluated in order to test the convenience of the method.
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Bartels, Larry M. "Panel Effects in the American National Election Studies." Political Analysis 8, no. 1 (1999): 1–20. http://dx.doi.org/10.1093/oxfordjournals.pan.a029802.
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Parallel panel and fresh cross-section samples in recent National Election Study surveys provide valuable leverage for assessing the magnitude of biases in statistical analyses of survey data due to panel attrition and panel conditioning. My analyses employing a variety of typical regression models suggest that substantial panel biases are likely to be fairly rare in these data, even when panel and cross-section respondents have markedly different characteristics. However, two of the dependent variables considered here—campaign interest and turnout—do appear to be sufficiently sensitive to panel effects to warrant significant discounting or adjustment of panel data. I propose adjustments for panel effects in both cross-sectional and dynamic analyses, based upon variants of the “fractional pooling” (Bartels 1996) and “two-stage auxiliary instrumental variables” (Franklin 1990) methods.
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Rafezy, B., and W. P. Howson. "Exact dynamic stiffness matrix for a thin-walled beam of doubly asymmetric cross-section filled with shear sensitive material." International Journal for Numerical Methods in Engineering 69, no. 13 (August 31, 2006): 2758–79. http://dx.doi.org/10.1002/nme.1864.
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LIPATOV, A. V., and N. P. ZOTOV. "STUDY OF BFKL GLUON DYNAMICS IN HEAVY QUARKONIUM PHOTOPRODUCTION AT HERA." Modern Physics Letters A 15, no. 10 (March 28, 2000): 695–707. http://dx.doi.org/10.1142/s0217732300000682.
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In the framework of semihard QCD approach we consider the processes of inelastic heavy quarkonium photoproduction at HERA with emphasis on the BFKL dynamics of gluon distributions. We investigate the dependences of the total cross-section of inelastic J/Ψ photoproduction and also pT and z spectra on different forms of the unintegrated gluon distribution. It is shown that the total cross-section is most sensitive to the Pomeron intercept parameter Δ. We compare the theoretical results with the available H1 and ZEUS experimental data.
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Chen, Wei, and Zi Xing Lu. "Dynamic Crushing Behavior of the High-Density Closed-Cell Foams." Advanced Materials Research 306-307 (August 2011): 485–88. http://dx.doi.org/10.4028/www.scientific.net/amr.306-307.485.
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The face-centered cubic model is used to investigate the dynamic crushing behavior of high density closed-cell foams. The influences of the constant loading rate and the specimen aspect ratio on the crushing stress were discussed. It is demonstrated that the crushing stress is more sensitive to the constant loading rate than the specimen aspect ratio. To describe the dynamic crushing behavior of the foam theoretically, the idealized rigid-perfectly plastic-locking (RPPL) stress-strain model is extended to a more general case, in which both the density and the cross-section area are discontinuous. The good agreement between the finite element results and theoretical results confirms that the dynamic crushing behavior of foam can be described by the modified RPPL stress-strain model.
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SHARIATI, MOHSEN, and FARIBA KHOSRAVINEJAD. "THE LASER-ASSISTED FIELD EFFECT TRANSISTOR GAS SENSOR BASED ON MORPHOLOGICAL ZINC-EXCITED TIN-DOPED In2O3 NANOWIRES." Surface Review and Letters 24, no. 08 (December 2017): 1750113. http://dx.doi.org/10.1142/s0218625x1750113x.
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The gas nanosensor of indium oxide nanowires in laser assisted approach, doped with tin and zinc for gas sensing and 1D growth purposes respectively, was reported. The nanowires were very sensitive to H2S gas in low concentration of 20[Formula: see text]ppb gas at room temperature. The fast dynamic intensive and sensitive response to gas was in a few seconds with an on/off sensitivity ratio of around 10. The square cross-section indium oxide nanowires were fabricated through physical vapor deposition (PVD) mechanism and annealing approach. The field emission scanning electron microscopy (FESEM) observations indicated that the annealing temperature was vital in nanostructures’ morphology. The fabricated nanowires for the optimized annealing temperature in applied growth technique were around 60[Formula: see text]nm in diameter.
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Wouters, Peter, and Armand van Deursen. "Thermal Distortion of Signal Propagation Modes Due to Dynamic Loading in Medium-Voltage Cables." Energies 13, no. 17 (August 27, 2020): 4436. http://dx.doi.org/10.3390/en13174436.
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Temperature variation from dynamic cable loading affects the propagation characteristics of transient signals. The distortion of modal signal components as a function of temperature in a three-phase medium-voltage cable is investigated. The temperature influence arises mainly through the complex insulation permittivity, which has a non-linear relationship with temperature. Near the maximum operating temperature of the cross-linked polyethylene insulation, the propagation velocity increases by 0.56% per degree centigrade but is an order of magnitude less sensitive at ambient temperature. The paper presents modeling results based on cable impedance and admittance matrices obtained from electromagnetic field simulation, taking into account the time-varying temperature distribution in the cable cross-section. The results are verified by applying Rayleigh–Schrödinger perturbation analysis. In the time domain, signal patterns shift when the modal propagation velocities change upon cable loading. Moreover, separation of degenerate modes is observed when the cable phase conductors carry an unbalanced current. The perspectives for exploiting the temperature dependency of signal propagation for pinpointing cable defects and for dynamic rating of underground power cables are discussed.
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Li, Hui, Gao Cheng, Yongjian Liu, and Dan Zhong. "Anomalous Thermal Response of Graphene Kirigami Induced by Tailored Shape to Uniaxial Tensile Strain: A Molecular Dynamics Study." Nanomaterials 10, no. 1 (January 9, 2020): 126. http://dx.doi.org/10.3390/nano10010126.
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The mechanical and thermal properties of graphene kirigami are strongly dependent on the tailoring structures. Here, thermal conductivity of three typical graphene kirigami structures, including square kirigami graphene, reentrant hexagonal honeycomb structure, and quadrilateral star structure under uniaxial strain are explored using molecular dynamics simulations. We find that the structural deformation of graphene kirigami is sensitive to its tailoring geometry. It influences thermal conductivity of graphene by changing heat flux scattering, heat path, and cross-section area. It is found that the factor of cross-section area can lead to four times difference of thermal conductivity in the large deformation system. Our results are elucidated based on analysis of micro-heat flux, geometry deformation, and atomic lattice deformation. These insights enable us to design of more efficient thermal management devices with elaborated graphene kirigami materials.
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LIU, JIAN YE, WEN-JUN GUO, WEI ZUO, and XI GUO LEE. "STUDIES FOR THE EQUATION OF STATE IN THE ISOSPIN ASYMMETRICAL NUCLEAR INTERACTIONS." International Journal of Modern Physics E 18, no. 03 (March 2009): 675–91. http://dx.doi.org/10.1142/s0218301309012793.
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In order to determine the equation of state in the isospin asymmetrical nuclear interactions, we have found the observables for extracting the information of them within the isospin-dependent quantum molecular dynamics in recent years. The several sensitive probes for extracting the information of the in-medium nucleon–nucleon cross section and the symmetry potential have found; meanwhile, their mechanisms are investigated in more details. The main point in this paper gives the summary for above probes and their outlook in the future.
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Dargay, Joyce M., Jean-Loup Madre, and Akli Berri. "Car Ownership Dynamics Seen Through the Follow-Up of Cohorts: Comparison of France and the United Kingdom." Transportation Research Record: Journal of the Transportation Research Board 1733, no. 1 (January 2000): 31–38. http://dx.doi.org/10.3141/1733-05.
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The dynamics of car ownership based on age-cohort data constructed from repeated cross-section surveys is investigated for France and the United Kingdom, both nationally and for different geographic areas. Two different modeling strategies are used: a demographic approach and a dynamic econometric approach. The demographic approach is primarily oriented toward long-term forecasting. It takes into account changes in car ownership over the life cycle for each generation, differences between generations, and period effects explained by income and prices. The dynamic econometric approach is mainly concerned with estimating the elasticity of car ownership with respect to income and prices in the short and long run. It is based on a dynamic model in which household car ownership is specified as a function of income, prices, sociodemographic factors, and previous car ownership. The results using the two approaches are quite similar. The income elasticity is significantly higher in the United Kingdom than in France, is higher in rural than in urban areas, and decreases over time as car ownership increases. Generation gaps, which have been important between older generations, are not significant for households whose head was born after the 1940s, which implies that the diffusion of car ownership over generations is nearing completion. In addition, a declining income elasticity confirms a progressive evolution toward saturation. Finally, car ownership is considerably more sensitive to car purchase prices than to gasoline prices and both appear to be more significant in densely populated zones than in rural areas.
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Ghasemi, Abbas, and Xianguo Li. "Cross-sectional reshaping of perturbed/unperturbed rectangular jets." International Journal of Numerical Methods for Heat & Fluid Flow 29, no. 7 (July 1, 2019): 2206–23. http://dx.doi.org/10.1108/hff-09-2018-0479.
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Purpose This study aims to investigate the cross-sectional reshaping in transitioning/starting rectangular jets of aspect ratio 2 under various inlet perturbation conditions at the Reynolds number of Re = UDh/v = 17,750. Design/methodology/approach Large eddy simulation results compared with the phase-locked particle image velocimetry data exhibit the cross-sectional jet deformations from rectangular to rounder shapes. Inflow velocity oscillations are introduced at the fundamental frequency associated with the Kelvin–Helmholtz instability characterized by the spectral analysis of the hotwire data and the linear stability predictions. Findings The initially rectangular cross-section of the jet reshapes into the rounder geometries with increased downstream distance while the edges of the jet become distorted due to the shear layer instability more significantly observed near the high curvature corners. The different expansion rates in the longer and shorter edges of the jet and the consequent cross-sectional reshaping are found to be sensitive to small levels of random inlet perturbations. In addition, introducing controlled sinusoidal oscillations results in the formation of more organized trailing shear layer where the stronger vortex rings go through the curvature-induced deformations. Originality/value Spatio-temporal study of vortex dynamics in transitioning rectangular jets reveals important information about the effect of the controlled jet forcing on local entrainment. Dynamics of the leading vortex dominates the entrainment in transitioning jets which are commonly used in practical applications. Near-field entrainment is also promoted proportional to the amplitude of the controlled inlet oscillations within the trailing vortex rings.
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Berger, EJ. "Friction modeling for dynamic system simulation." Applied Mechanics Reviews 55, no. 6 (October 16, 2002): 535–77. http://dx.doi.org/10.1115/1.1501080.
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Friction is a very complicated phenomenon arising at the contact of surfaces. Experiments indicate a functional dependence upon a large variety of parameters, including sliding speed, acceleration, critical sliding distance, temperature, normal load, humidity, surface preparation, and, of course, material combination. In many engineering applications, the success of models in predicting experimental results remains strongly sensitive to the friction model. Furthermore, a broad cross section of engineering and science disciplines have developed interesting ways of representing friction, with models originating from the fundamental mechanics areas, the system dynamics and controls fields, as well as many others. A fundamental unresolved question in system simulation remains: what is the most appropriate way to include friction in an analytical or numerical model, and what are the implications of friction model choice? This review article draws upon the vast body of literature from many diverse engineering fields and critically examines the use of various friction models under different circumstances. Special focus is given to specific topics: lumped-parameter system models (usually of low order)—use of various types of parameter dependence of friction; continuum system models—continuous interface models and their discretization; self-excited system response—steady-sliding stability, stick/slip, and friction model requirements; and forced system response—stick/slip, partial slip, and friction model requirements. The conclusion from this broad survey is that the system model and friction model are fundamentally coupled, and they cannot be chosen independently. Furthermore, the usefulness of friction model and the success of the system dynamic model rely strongly on each other. Across disciplines, it is clear that multi-scale effects can dominate performance of friction contacts, and as a result more research is needed into computational tools and approaches capable of resolving the diverse length scales present in many practical problems. There are 196 references cited in this review-article.
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Regan, Marc A., and Krishnan Mahesh. "Adjoint sensitivity and optimal perturbations of the low-speed jet in cross-flow." Journal of Fluid Mechanics 877 (August 22, 2019): 330–72. http://dx.doi.org/10.1017/jfm.2019.582.
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The tri-global stability and sensitivity of the low-speed jet in cross-flow are studied using the adjoint equations and finite-time horizon optimal disturbance analysis at Reynolds number $Re=2000$, based on the average velocity at the jet exit, the jet nozzle exit diameter and the kinematic viscosity of the jet, for two jet-to-cross-flow velocity ratios $R=2$ and $4$. A novel capability is developed on unstructured grids and parallel platforms for this purpose. Asymmetric modes are more important to the overall dynamics at $R=4$, suggesting increased sensitivity to experimental asymmetries at higher $R$. Low-frequency modes show a connection to wake vortices. Adjoint modes show that the upstream shear layer is most sensitive to perturbations along the upstream side of the jet nozzle. Lower frequency downstream modes are sensitive in the cross-flow boundary layer. For $R=2$, optimal analysis reveals that for short time horizons, asymmetric perturbations dominate and grow along the counter-rotating vortex pair observed in the cross-section. However, as the time horizon increases, large transient growth is observed along the upstream shear layer. When $R=4$, the optimal perturbations for short time scales grow along the downstream shear layer. For long time horizons, they become hybrid modes that grow along both the upstream and downstream shear layers.
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Peister, Cale, Cameron O’Keeffe, Jose Imbert, Clifford Butcher, Michael Worswick, Skye Malcolm, Jim Dykeman, Cyrus Yau, Ron Soldaat, and Willie Bernert. "Dynamic and Quasi-Static Testing and Modeling of Hot Stamped Tailor-Welded Axial Crush Rails." Proceedings 2, no. 8 (September 26, 2018): 526. http://dx.doi.org/10.3390/icem18-05401.
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In the current research, the use of tailor-welded blanks (TWBs) comprising Usibor® 1500-AS laser welded to more ductile Ductibor® 500-AS is considered. The TWBs were hot stamped to form top-hat cross-section channels with axially tailored properties. Axial crush rails were assembled by spot welding together two of these hot stamped channels along their flanges. The tailored rails were crush tested under dynamic (crash) and quasi-static conditions using an 855 kg crash sled facility at 10.6 m/s impact speed, and a 670 kN servo-hydraulic press at 0.5 mm/s, respectively. Non-tailored channels composed entirely of Ductibor® 500-AS were also tested for base material characterization and as a comparison to the tailored conditions. Numerical models of the crash experiments were developed. The material models include measured fracture loci using the generalized incremental stress state dependent damage model (GISSMO), with rate sensitive constitutive behavior. Spot weld failure was also considered based on tests of spot welded coupons. The accuracy of the predicted force-displacement and energy absorption response, extent of parent metal cracking, and extent of weld failure are evaluated in comparison to the experiments. The difference in response between quasi-static and dynamic testing is also evaluated.
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Young, Gavin, and Philipp Kukura. "Interferometric Scattering Microscopy." Annual Review of Physical Chemistry 70, no. 1 (June 14, 2019): 301–22. http://dx.doi.org/10.1146/annurev-physchem-050317-021247.
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Interferometric scattering microscopy (iSCAT) is an extremely sensitive imaging method based on the efficient detection of light scattered by nanoscopic objects. The ability to, at least in principle, maintain high imaging contrast independent of the exposure time or the scattering cross section of the object allows for unique applications in single-particle tracking, label-free imaging of nanoscopic (dis)assembly, and quantitative single-molecule characterization. We illustrate these capabilities in areas as diverse as mechanistic studies of motor protein function, viral capsid assembly, and single-molecule mass measurement in solution. We anticipate that iSCAT will become a widely used approach to unravel previously hidden details of biomolecular dynamics and interactions.
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Mason, T. E., and A. D. Taylor. "Neutron Scattering in Materials Research." MRS Bulletin 24, no. 12 (December 1999): 14–16. http://dx.doi.org/10.1557/s0883769400053665.
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With materials of ever-increasing complexity becoming key elements of the technologies underpinning industrial and economic development, there is an ongoing need for tools that reveal the microscopic origins of physical, electrical, magnetic, chemical, and biological properties. Neutron scattering is one such powerful tool for the study of the structure and dynamics of materials. Neutrons are well suited to this purpose for several reasons:∎ Neutrons are electrically neutral, leading to penetration depths of centimeters and thereby enabling in situ studies.∎ Neutron cross sections exhibit no regular dependence on atomic number and are similar in magnitude across the periodic table, giving rise to sensitivity to light elements in the presence of heavier ones.∎ Certain large differences in isotopic scattering cross sections (e.g., hydrogen to deuterium, H/D) make neutrons especially useful for the study of light atoms in materials.∎ The range of momentum transfer available allows probing of a broad range of length scales (0.1–105 Å), important in many different materials and applications.∎ Thermal and “cold” (longer-wavelength) neutrons cover a range of energies sufficient to probe a wide range of lattice or magnetic excitations, “slow” dynamic processes such as polymer chain reptation, and so forth.∎ Neutrons have magnetic moments and are thus uniquely sensitive probes of magnetic interactions.∎ Neutrons can be polarized, allowing the cross sections (magnetic and non-magnetic) to be separated.∎ The simplicity of the magnetic and nuclear interactions makes interpretation of results straightforward.
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Milovanović, Predrag, Petar Kljajić, Tatjana Popović, Goran Andrić, and Marijana Pražić-Golić. "Dynamic of Brassicogethes aeneus (F.) (Coleoptera, Nitidulidae) populations in Serbia’s downriver Danube section and their susceptibility to insecticides." Spanish Journal of Agricultural Research 17, no. 2 (July 26, 2019): e1008. http://dx.doi.org/10.5424/sjar/2019172-14219.
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This paper presents data on the dynamic of B. aeneus populations in winter oilseed rape in the downriver section of the Danube in Serbia, which were acquired by yellow water traps and a beating method. Their susceptibility to several insecticides of different classes (organophosphates, pyrethroids and neonicotinoids) (adult vial test and dipping test) was tested over two seasons (2009 and 2010). B. aeneus populations developing under the agroecological conditions that exist in Serbia were monitored to detect the moment of OSR infestation during its sensitive growth stages. Adults were counted, and the data revealed that they infest winter OSR crops during the stem elongation growth stage (BBCH 30-31), reaching a population peak at the green-yellow bud stage (BBCH 57-59), and exceeding the economic threshold, while the populations decreased substantially during the subsequent stage (BBCH 61-69). Laboratory test results did not confirm any changes in B. aeneus susceptibility/resistance to pyrethroid, organophosphate and neonicotinoid insecticides. Migration of B. aeneus populations was monitored as a way of developing predictive models for estimation of infestation severity and the timing of pest outbreaks under agroecological conditions existing in Serbia. As resistance to pyrethroids has been confirmed in B. aeneus populations in many European countries, their susceptibility will be further monitored.
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Mansyur, Carol Leler, Benjamin C. Amick, Ronald B. Harrist, Luisa Franzini, and Robert E. Roberts. "The Cultural Production of Health Inequalities: A Cross-Sectional, Multilevel Examination of 52 Countries." International Journal of Health Services 39, no. 2 (April 2009): 301–19. http://dx.doi.org/10.2190/hs.39.2.e.
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In a 2001 report, the U.S. National Institutes of Health called for more integration of the social sciences into health-related research, including research guided by theories and methods that take social and cultural systems into consideration. Based on a theoretical framework that integrates Hofstede's cultural dimensions with sociological theory, the authors used multilevel modeling to explore the association of culture with structural inequality and health disparities. Their results support the idea that cultural dimensions and social structure, along with economic development, may account for much of the cross-national variation in the distribution of health inequalities. Sensitivity tests also suggest that an interaction between culture and social structure may confound the relationship between income inequality and health. It is necessary to identify important cultural and social structural characteristics before we can achieve an understanding of the complex, dynamic systems that affect health, and develop culturally sensitive interventions and policies. This study takes a step toward identifying some of the relevant cultural and structural influences. More research is needed to explore the pathways leading from the sociocultural environment to health inequalities.
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Gosteev, Yu A., A. D. Obukhovskiy, and S. D. Salenko. "Numerical simulation of the transverse flow over spans of girder bridges." Advanced Engineering Research 18, no. 4 (December 26, 2018): 362–78. http://dx.doi.org/10.23947/1992-5980-2018-18-4-362-378.
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Introduction. The technique of numerical modeling of the transverse flow over span structures of bridges on the basis of the two-dimensional URANS (Unsteady Reynolds-averaged Navier-Stokes) approach used in the modern methods and software packages for computational fluid dynamics is verified. The work objective was debugging and experimental substantiation of this technique with the use of the database on the aerodynamic characteristics of the cross-sections of span structures of girder bridges of standard shapes pre-developed by the authors.Materials and Methods. A numerical simulation of the transverse flow of low-turbulent (smooth) and turbulent air flows around the bridge structures in a range of practically interesting attack angles is carried out. SST k − ω turbulence model was used as the closing one. The technique was preliminarily tested on the check problem for the flow of the rectangular crosssection beams. Calculations were carried out using the licensed ANSYS software.Research Results. The calculated dependences on the attack angle of the aerodynamic coefficients of forces (drag and lift) and the moment of the cross sections of the girder bridges of standard shapes are obtained. These data refer to the span structures at the construction phase (without deck and parapets, without parapets) and operation phase, under the conditions of model smooth and turbulent incoming flow. The latter allows us to outline the boundaries for more weighted estimates of the aerodynamic characteristics of thegirder bridges in a real wind current. The best agreement with the experimental data was obtained from the drag of the cross-section. The magnitude of the lifting force is more sensitive to the presence and extent of the separation regions, so its numerical determination is less accurate. The reproduction of the angle-of-attack effect on the aerodynamic moment of the cross-section is the most challenging for the majority of configurations.Discussion and Conclusions. Comparison of the calculated and experimental data indicates the applicability of the URANS approach to the operational prediction of the aerodynamic characteristics of the single-beam span structures. In the case of multi-beam span structures, where the aerodynamic interference between separate girders plays an important role, the URANS approach must apparently give way to more accurate eddy-resolving methods. The results obtained can be used in the aerodynamic analysis of structures and in practice of the relevant design organizations in the field of transport construction.
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Majdalani, Samer, Jean-Philippe Chazarin, and Roger Moussa. "A New Water Level Measurement Method Combining Infrared Sensors and Floats for Applications on Laboratory Scale Channel under Unsteady Flow Regime." Sensors 19, no. 7 (March 28, 2019): 1511. http://dx.doi.org/10.3390/s19071511.
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In this paper, we studied water transport under an unsteady flow regime in an experimental channel (4 m in length; 3 cm in width). Our experiments implicated some measuring requirements, specifically, a water level (WL) detection technique that is able to measure WL in a range of 2 cm with a precision of 1 mm. The existing WL detection techniques could not meet our measurement requirements. Therefore, we propose a new measurement method that combines two approaches: An “old” water contact technique (float) with a “new” remote non-contact technique (infrared sensor). We used an extruded polystyrene (XPS Foam) that needed some adequate treatment before using it as float in experimental measurements. The combination of IR-sensors with treated float foam lead to a sensitive measurement method that is able to detect flat and sharp flow signals, as well as highly dynamic variations of water surface level. Based on the experimental measurements of WL and outflow at the channel output, we deduced a loop rating curve that is suitable with a power law adjustment. The new measurement method could be extended to larger scale applications like rivers and more complicated cross section geometry of irregular shape.
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Lund, Fernando, and Bruno Scheihing-Hitschfeld. "The Scattering of Phonons by Infinitely Long Quantum Dislocations Segments and the Generation of Thermal Transport Anisotropy in a Solid Threaded by Many Parallel Dislocations." Nanomaterials 10, no. 9 (August 29, 2020): 1711. http://dx.doi.org/10.3390/nano10091711.
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A canonical quantization procedure is applied to the interaction of elastic waves—phonons—with infinitely long dislocations that can oscillate about an equilibrium, straight line, configuration. The interaction is implemented through the well-known Peach–Koehler force. For small dislocation excursions away from the equilibrium position, the quantum theory can be solved to all orders in the coupling constant. We study in detail the quantum excitations of the dislocation line and its interactions with phonons. The consequences for the drag on a dislocation caused by the phonon wind are pointed out. We compute the cross-section for phonons incident on the dislocation lines for an arbitrary angle of incidence. The consequences for thermal transport are explored, and we compare our results, involving a dynamic dislocation, with those of Klemens and Carruthers, involving a static dislocation. In our case, the relaxation time is inversely proportional to frequency, rather than directly proportional to frequency. As a consequence, the thermal transport anisotropy generated on a material by the presence of a highly-oriented array of dislocations is considerably more sensitive to the frequency of each propagating mode, and, therefore, to the temperature of the material.
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Sier, Daniel, Geoffrey P. Cousland, Ryan M. Trevorah, Ruwini S. K. Ekanayake, Chanh Q. Tran, James R. Hester, and Christopher T. Chantler. "High accuracy determination of photoelectric cross sections, X-ray absorption fine structure and nanostructure analysis of zinc selenide using the X-ray extended range technique." Journal of Synchrotron Radiation 27, no. 5 (August 17, 2020): 1262–77. http://dx.doi.org/10.1107/s1600577520010097.
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Measurements of mass attenuation coefficients and X-ray absorption fine structure (XAFS) of zinc selenide (ZnSe) are reported to accuracies typically better than 0.13%. The high accuracy of the results presented here is due to our successful implementation of the X-ray extended range technique, a relatively new methodology, which can be set up on most synchrotron X-ray beamlines. 561 attenuation coefficients were recorded in the energy range 6.8–15 keV with measurements concentrated at the zinc and selenium pre-edge, near-edge and fine-structure absorption edge regions. This accuracy yielded detailed nanostructural analysis of room-temperature ZnSe with full uncertainty propagation. Bond lengths, accurate to 0.003 Å to 0.009 Å, or 0.1% to 0.3%, are plausible and physical. Small variation from a crystalline structure suggests local dynamic motion beyond that of a standard crystal lattice, noting that XAFS is sensitive to dynamic correlated motion. The results obtained in this work are the most accurate to date with comparisons with theoretically determined values of the attenuation showing discrepancies from literature theory of up to 4%, motivating further investigation into the origin of such discrepancies.
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Hyvärinen, Jari, Matts Karlsson, and Lin Zhou. "Study of concept for hydraulic hose dynamics investigations to enable understanding of the hose fluid–structure interaction behavior." Advances in Mechanical Engineering 12, no. 4 (April 2020): 168781402091611. http://dx.doi.org/10.1177/1687814020916110.
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Fatigue failure of a hydraulic hose systems, caused by violent vibrations, has become a critical factor creating operational and maintenance cost for the end user of rock drill equipment. Similar behavior is also appearing in, for example, forestry machines. Hoses are used as parts of the energy feeding system in machines such as the ones use for mining and civil construction operations. This work aims to create an understanding of the dynamic behavior of a selected hydraulic hose. The numerical modeling approach selected includes a boundary element method approach in the fluid-elastic analysis of the dynamics of a pressurized hose with conveying fluid. Experimental modal analysis was used to validate the numerical model. Pre-tension and pressure-induced tension were monitored with an in-house-developed strain gauge–based load cell. The analysis and experiments show that a complex coupling, of pure structural bending modes, appears when the hose is subjected to internal flow. Some of the modeshapes show a circular motion of the hose cross sections. As shown in this article, these coupled modes become increasingly sensitive to external or internal excitation with increasing flow rate. To illustrate the strength of the proposed approach, the second part of the work in this article presents a parametric study of hose dynamics for hoses with typical dimensions used in industrial applications. This investigation of how different parameters influence the dynamic characteristics of hydraulic hoses shows, for example, that hose end-support stiffness has a large impact on the stability and dynamic behavior of the hose. A soft support tends to create a static instability–type behavior where the lowest frequency mode frequency decreases to levels close to zero with increasing flow speed. Pre-tension of the hose has a stabilizing effect on the hose dynamics. In the case when the internal pressure of the hydraulic hose does not generate tension of the hose, then the increase or decrease in the internal pressure has limited influence on the hose dynamics: this is at least a conclusion valid in the investigated 100–210 bar pressure range. In addition, a smaller diameter hose is more sensitive than a larger diameter hose, and this is valid as long as the pre-tension is high enough to maintain static stability in the entire flow rate range.
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O’Connor, Evan, C. J. Horowitz, Zidu Lin, and Sean Couch. "Core-Collapse Supernova Simulations including Neutrino Interactions from the Virial EOS." Proceedings of the International Astronomical Union 12, S331 (February 2017): 107–12. http://dx.doi.org/10.1017/s1743921317004586.
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AbstractCore-collapse supernova explosions are driven by a central engine that converts a small fraction of the gravitational binding energy released during core collapse to outgoing kinetic energy. The suspected mode for this energy conversion is the neutrino mechanism, where a fraction of the neutrinos emitted from the newly formed protoneutron star are absorbed by and heat the matter behind the supernova shock. Accurate neutrino-matter interaction terms are crucial for simulating these explosions. In this proceedings for IAUS 331, SN 1987A, 30 years later, we explore several corrections to the neutrino-nucleon scattering opacity and demonstrate the effect on the dynamics of the core-collapse supernova central engine via two dimensional neutrino-radiation-hydrodynamics simulations. Our results reveal that the explosion properties are sensitive to corrections to the neutral-current scattering cross section at the 10-20% level, but only for densities at or above ~1012 g cm−3.
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Xie, Yurun, Hailin Zhao, Yufeng Wang, Yin Huang, Tao Wang, Xin Xu, Chunlei Xiao, Zhigang Sun, Dong H. Zhang, and Xueming Yang. "Quantum interference in H + HD → H2 + D between direct abstraction and roaming insertion pathways." Science 368, no. 6492 (May 14, 2020): 767–71. http://dx.doi.org/10.1126/science.abb1564.
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Understanding quantum interferences is essential to the study of chemical reaction dynamics. Here, we provide an interesting case of quantum interference between two topologically distinct pathways in the H + HD → H2 + D reaction in the collision energy range between 1.94 and 2.21 eV, manifested as oscillations in the energy dependence of the differential cross section for the H2 (v′ = 2, j′ = 3) product (where v′ is the vibrational quantum number and j′ is the rotational quantum number) in the backward scattering direction. The notable oscillation patterns observed are attributed to the strong quantum interference between the direct abstraction pathway and an unusual roaming insertion pathway. More interestingly, the observed interference pattern also provides a sensitive probe of the geometric phase effect at an energy far below the conical intersection in this reaction, which resembles the Aharonov–Bohm effect in physics, clearly demonstrating the quantum nature of chemical reactivity.
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He, C., K. N. Liou, Y. Takano, R. Zhang, M. Levy Zamora, P. Yang, Q. Li, and L. R. Leung. "Variation of the radiative properties during black carbon aging: theoretical and experimental intercomparison." Atmospheric Chemistry and Physics 15, no. 20 (October 28, 2015): 11967–80. http://dx.doi.org/10.5194/acp-15-11967-2015.
Full textAbstract:
Abstract. A theoretical black carbon (BC) aging model is developed to account for three typical evolution stages, namely, freshly emitted aggregates, BC coated by soluble material, and BC particles undergoing further hygroscopic growth. The geometric-optics surface-wave (GOS) approach is employed to compute the BC single-scattering properties at each aging stage, which are subsequently compared with laboratory measurements. Theoretical calculations are consistent with measurements in extinction and absorption cross sections for fresh BC aggregates with different BC sizes (i.e., mobility diameters of 155, 245, and 320 nm), with differences of ≤ 25 %. The measured optical cross sections for BC coated by sulfuric acid and for that undergoing further hygroscopic growth are generally captured (differences < 30 %) by theoretical calculations using a concentric core-shell structure, with an overestimate in extinction and absorption of the smallest BC size and an underestimate in scattering of the largest BC size. We find that the absorption and scattering cross sections of fresh BC aggregates vary by 20–40 and 50–65 %, respectively, due to the use of upper (1.95–0.79i) and lower (1.75–0.63i) bounds of BC refractive index, while the variations are < 20 % in absorption and < 50 % in scattering in the case of coated BC particles. Sensitivity analyses of the BC morphology show that the optical properties of fresh BC aggregates are more sensitive to fractal dimension than primary spherule size. The absorption and scattering cross sections of coated BC particles vary by more than a factor of 2 due to different coating structures. We find an increase of 20–250 % in absorption and a factor of 3–15 in scattering during aging, significantly depending on coating morphology and aging stages. This study suggests that an accurate estimate of BC radiative effects requires the incorporation of a dynamic BC aging process that accounts for realistic coating structures in climate models.
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Zhang, Bei Chen, Qing Lian Li, Yuan Wang, and Jian Qiang Zhang. "Analysis of Two-Phase Pressure Drop Fluctuation Characteristics in a Single Mini-Channel." Defect and Diffusion Forum 366 (April 2016): 151–56. http://dx.doi.org/10.4028/www.scientific.net/ddf.366.151.
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Two-phase pressure drop fluctuations during flow boiling in a single mini-channel were experimentally investigated. Degassed water was tested in circular cross section mini-channels with the hydraulic diameter of 1.0 mm at liquid mass fluxes range of 21.19-84.77 kg m-2 s-1 and heat fluxes of 0~155.75 kW m-2. Effects of heat flux and mass flux on pressure drop fluctuations were discussed based on the time and frequency domain analysis of the measured pressure drop. Two types of fluctuations were identified, which are the incipient boiling fluctuation (IBF) and the explosive boiling fluctuation (EBF) respectively. The IBF is a low frequency low amplitude fluctuation, which relates to the bubble dynamics when incipient boiling occurs. It is sensitive to the thermal and flow conditions. With the increase of heat flux and mass flux, the IBF is suppressed. The EBF is a low frequency high amplitude fluctuation, which occurs near the critical heat flux.
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Lampert, Martina. "Attention to Quotation(s): From Activation to Inhibition." Cognitive Semantics 3, no. 2 (August 29, 2017): 182–216. http://dx.doi.org/10.1163/23526416-00302003.
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In the spirit of Talmy’s recent remark on desirable extensions of cognitive semantics into discourse analysis and multimodality, this paper outlines an agenda for framing quotation as an attention- and modality-sensitive phenomenon. A quotation’s distinct discourse function by itself – naturally – calls for an attention-driven analysis, and the representational subsystems of language yield modality-specific manifestations: Conventionalized figural delimiters prompt quotations’ metalinguistic and verbatim status in writing, while in (casual) speech they tend to stand out through vocal dynamics and visible bodily actions. With recourse to Talmy’s attention-based trigger-and-target construct, I will scrutinize a cross-section of videotaped samples of quoting by experienced us speakers from different speech genres in public settings, to demonstrate orally performed quotations’ responsiveness to attentional gradience: Exhibiting patterns of activation, attenuation, inhibition, and sustainment in indexing ‘the other voice,’ the case studies illustrate multiple effects of fore- and backgrounding ensuing from the different modalities’ complex interactions.
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Tatsumi, Kazuyoshi, Shunsuke Muto, and Ján Rusz. "Energy Loss by Channeled Electrons: A Quantitative Study on Transition Metal Oxides." Microscopy and Microanalysis 19, no. 6 (August 29, 2013): 1586–94. http://dx.doi.org/10.1017/s1431927613013214.
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AbstractElectron energy-loss spectroscopy (EELS) attached to current transmission electron microscopes can probe not only element-selective chemical information, but also site-selective information that depends on the position that a specific element occupies in a crystal lattice. The latter information is exploited by utilizing the Bloch waves symmetry in the crystal, which changes with its orientation with respect to the incident electron wave (electron channeling). We demonstrate the orientation dependence of the cross-section of the electron energy-loss near-edge structure for particular crystalline sites of spinel ferrites, by quantitatively taking into account the dynamical diffraction effects with a large number of the diffracted beams. The theoretical results are consistent with a set of experiments in which the transition metal sites in spinel crystal structures are selectively excited. A new measurement scheme for site-selective EELS using a two-dimensional position-sensitive detector is proposed and validated by theoretical predictions and trial experiments.
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LIU, JIAN-YE, YONG ZHONG XING, HANG LIU, WEN-JUN GUO, and XI GUO LEE. "ENTRANCE CHANNEL EFFECTS ON THE ISOSPIN FRACTIONATION AT INTERMEDIATE ENERGY HEAVY ION COLLISIONS." International Journal of Modern Physics E 14, no. 04 (June 2005): 587–97. http://dx.doi.org/10.1142/s0218301305003430.
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We investigate the dependence of isospin fractionation degree on the entrance channel condition, which includes the impact parameter, the beam energy, the mass and the neutron–proton ratio of the colliding system as well as quantifying the gas phase and the liquid phase by using the isospin dependent quantum molecular dynamics model. We found that the isospin fractionation degree increases markedly with the enhancements of the neutron–proton ratio of system and the beam energy; however, it decreases with increasing system mass as well as slowly increases with the enhancement of the impact parameter. In particular, the property for the sensitive dependence of isospin fractionation degree on the symmetry potential and its weak dependence on the in-medium nucleon–nucleon cross-section is preserved for all the neutron-rich systems and all the impact parameters in the relative lower beam energy region. In this case, the isospin fractionation degree for all the neutron-rich systems can be directly compared with the experimental data to extract the information on the symmetry potential in the relative lower beam energy region.
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M. Adam, Anokye, and Imran Sharif Chaudhry. "The currency union effect on intra-regional trade in Economic Community of West African States (ECOWAS)." Journal of International Trade Law and Policy 13, no. 2 (June 10, 2014): 102–22. http://dx.doi.org/10.1108/jitlp-04-2013-0008.
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Purpose – The purpose of this paper is to investigate the currency union (CU) effect on aggregate intra-trade in the Economic Community of West African States (ECOWAS) and on bilateral trade among individual countries using the gravity model. Design/methodology/approach – Using panel dynamic ordinary least square, we examined the short- and long-run CU effect on aggregate intra-ECOWAS trade and bilateral trade among ECOWAS countries from 1995 to 2010. Chow poolability test was conducted for the appropriateness of pooling the cross-section parameters as against individual model. The augmented Dickey–Fuller (ADF) test; the Phillips–Perron (PP) test; and the Kwiatkowski, Phillips, Schmidt and Shin (KPSS) test were conducted on the individual data series, and the Levin, Lin and Chu test; the Im, Pesaran and Shin test; the Breitung test; and the Hadri test were used for testing cross-sectional independent panel unit root tests. Kao panel cointegration test was conducted to identify long-run relationships. Findings – We found evidence of significant positive CU effect on aggregate intra-ECOWAS trade. The estimates also show that Benin, Burkina Faso, Niger, Senegal and Togo trade more with countries they share common currency with than what they would have been in both short and long run. We again observed that CU is insignificant in explaining Cote d’Ivoire, Mali and Senegal intra-trade with ECOWAS countries, though their observed intra-trade with ECOWAS is relatively high which is found to be explained by export diversification. Practical implications – The findings reveal that CU is good for aggregate intra-regional trade though some individual members respond negative to CU. The finding of diversification as a necessary tool to increase intra-regional trade imply that as effort of introducing single currency is being pursued rigorously, effort to diversify export or trade complement should not be overlooked. Originality/value – There exist panel studies on CU on aggregate intra-regional trade in ECOWAS. However, there is a need to have country level study to identify CU effect on each country, as it is sensitive to country-specific factors which are unobservable in time series analysis of group of countries. Also, our group estimate differs in methodology in the sense that the dynamic generalised least takes care of endogeneity in trade gravity literature.
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Fullerton, Eric E., Ivan K. Schuller, and Y. Bruynseraede. "Quantitative X-Ray Diffraction From Superlattices." MRS Bulletin 17, no. 12 (December 1992): 33–38. http://dx.doi.org/10.1557/s0883769400046935.
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The physical properties of superlattices have been the subject of considerable interest because a wide range of phenomena associated with very thin films, interfaces, and coupling effects can be studied. Recent areas of activity in metallic superlattices include antiferromagnetic coupling of ferromagnetic layers across nonmagnetic spacer layers, giant magnetoresistance, magnetic surface anisotropy, low-dimensional superconductivity, and anomalous mechanical properties. All of these phenomena are strongly affected by the chemical and physical properties of the individual layers and by the superlattice structure. Therefore, a detailed understanding of the properties of superlattices requires a nondestructive, quantitative determination of the superlattice structure.Because superlattices are not in thermodynamic equilibrium, their structure is sensitive to preparation methods and growth conditions. A dramatic example of superlattice structural dependence on growth conditions is shown in Figure 1, for sputtered Nb/Si superlattices. Increasing the Ar pressure during sputtering decreases the kinetic energy of the deposited atoms, thereby changing their surface mobility, and thus altering growth dynamics. Figure 1 shows the low-angle x-ray diffraction and cross-sectional transmission electron microscopy (TEM) images of [Nb(35 Å)/Si(25 Å)]40, superlattices sputtered in, respectively, 3 and 15 mTorr of Ar. The TEM image of the 3 mTorr superlattice clearly shows the smooth and continuous layering across the entire cross section of the image (≈5 μm). This is characteristic of sputtered metal/semiconductor superlattices used for x-ray optics.
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AHMAD, TAUSEEF, I. A. RIZVI, AVINASH AGARWAL, RAKESH KUMAR, K. S. GOLDA, and A. K. CHAUBEY. "REACTION MECHANISMS IN 12C+93Nb SYSTEM: EXCITATION FUNCTIONS AND RECOIL RANGE DISTRIBUTIONS BELOW 7 MeV/u." International Journal of Modern Physics E 20, no. 03 (March 2011): 645–55. http://dx.doi.org/10.1142/s0218301311018137.
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The experiments were performed to study excitation functions (EFs) of evaporation residues (ERs), i.e. 103,102,101Ag, 101,100,99Pd, 101,100Rh, 97Ru, 96Tc, 95Tc, 94Tc, 93Mo m , 92Nb m populated in the reactions induced by 12C on 93Nb for exploring the reaction dynamics involved at energies ≈ 47–75 MeV. The activation technique followed by offline γ-ray spectrometry has been employed to measure EFs. These measurements were simulated with other reported values available in literature as well as with theoretical predictions based on computer code PACE-2. The effect of variation of level density parameter involved in this code has also been studied. An excellent agreement was found between theoretical and experimental values in some of the fusion evaporation channels. However, significant enhancement of cross-section as observed in α-emission channels may be due to incomplete fusion (ICF) process and/or direct reaction process. To confirm the aforesaid reaction mechanism, Recoil Range Distributions (RRDs) of various ERs have been measured at ≈ 80 MeV. Moreover, an attempt is made to separate the percentage relative contributions of complete and incomplete fusion components from the analysis of the measured RRDs data. Further, the relative percentage ICF fraction, also estimated from EFs data, was found to be sensitive with the projectile energy.
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He, C., K. N. Liou, Y. Takano, R. Zhang, M. L. Zamora, P. Yang, Q. Li, and L. R. Leung. "Variation of the radiative properties during black carbon aging: theoretical and experimental intercomparison." Atmospheric Chemistry and Physics Discussions 15, no. 14 (July 20, 2015): 19835–72. http://dx.doi.org/10.5194/acpd-15-19835-2015.
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Abstract. A theoretical black carbon (BC) aging model is developed to account for three typical evolution stages, namely, freshly emitted aggregates, coated BC by soluble material, and BC particles undergoing further hygroscopic growth. The geometric-optics surface-wave (GOS) approach is employed to compute the BC single-scattering properties at each aging stage, which are subsequently compared with laboratory measurements. Theoretical calculations are consistent with measurements in extinction and absorption cross sections for fresh BC aggregates, but overestimate the scattering cross sections for BC mobility diameters of 155, 245, and 320 nm, because of uncertainties associated with theoretical calculations for small particles as well as laboratory scattering measurements. The measured optical cross sections for coated BC by sulfuric acid and for those undergoing further hygroscopic growth are captured by theoretical calculations using a concentric core-shell structure, with differences of less than 20 %. This suggests that the core-shell shape represents the realistic BC coating morphology reasonably well in this case, which is consistent with the observed strong structure compaction during aging. We find that the absorption and scattering properties of fresh BC aggregates vary by up to 60 % due to uncertainty in the BC refractive index, which, however, is a factor of two smaller in the case of coated BC particles. Sensitivity analyses on the BC morphology show that the optical properties of fresh BC aggregates are more sensitive to fractal dimension than primary spherule size. The absorption and scattering cross sections of coated BC particles vary by more than a factor of two due to different coating structures. We find an increase of 20–250 % in absorption and a factor of 3–15 in scattering during aging, significantly depending on coating morphology and aging stages. Applying the aging model to CalNex 2010 field measurements, we show that the resulting BC direct radiative forcing (DRF) first increases from 1.5 to 1.7 W m-2 and subsequently decreases to 1.0 W m-2 during the transport from the Los Angeles Basin to downwind regions, as a result of the competition between absorption enhancement due to coating and dilution of BC concentration. The BC DRF can vary by up to a factor of two due to differences in BC coating morphology. Thus, an accurate estimate of BC DRF requires the incorporation of a dynamic BC aging process that accounts for realistic morphology in climate models, particularly for the regional analysis with high atmospheric heterogeneity.
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Sanders, M. A., and J. L. Salisbury. "Centrin-mediated microtubule severing during flagellar excision in Chlamydomonas reinhardtii." Journal of Cell Biology 108, no. 5 (May 1, 1989): 1751–60. http://dx.doi.org/10.1083/jcb.108.5.1751.
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Chlamydomonas cells excise their flagella in response to a variety of experimental conditions (e.g., extremes of temperature or pH, alcohol or detergent treatment, and mechanical shear). Here, we show that flagellar excision is an active process whereby microtubules are severed at select sites within the transition zone. The transition zone is located between the flagellar axoneme and the basal body; it is characterized by a pair of central cylinders that have an H shape when viewed in longitudinal section. Both central cylinders are connected to the A tubule of each microtubule doublet of the transition zone by fibers (approximately 5 nm diam). When viewed in cross section, these fibers are seen to form a distinctive stellate pattern characteristic of the transition zone (Manton, I. 1964. J. R. Microsc. Soc. 82:279-285; Ringo. D. L. 1967. J. Cell Biol. 33:543-571). We demonstrate that at the time of flagellar excision these fibers contract and displace the microtubule doublets of the axoneme inward. We believe that the resulting shear force and torsional load act to sever the axonemal microtubules immediately distal to the central cylinder. Structural alterations of the transition zone during flagellar excision occur both in living cells and detergent-extracted cell models, and are dependent on the presence of calcium (greater than or equal to 10(-6) M). Immunolocalization using monoclonal antibodies against the calcium-binding protein centrin demonstrate the presence of centrin in the fiber-based stellate structure of the transition zone of wild-type cells. Examination of the flagellar autotomy mutant, fa-1, which fails to excise its flagella (Lewin, R., and C. Burrascano. 1983. Experientia. 39:1397-1398), demonstrates that the fa-1 lacks the ability to completely contract the fibers of the stellate structure. We conclude that flagellar excision in Chlamydomonas involves microtubule severing that is mediated by the action of calcium-sensitive contractile fibers of the transition zone. These observations have led us to question whether microtubule severing may be a more general phenomenon than previously suspected and to suggest that microtubule severing may contribute to the dynamic behavior of cytoplasmic microtubules in other cells.
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Zhukova, T. V. "Wavelike Character of Pension Reforms. First-wave 1994–2008." Outlines of global transformations: politics, economics, law 12, no. 6 (December 30, 2019): 130–51. http://dx.doi.org/10.23932/2542-0240-2019-12-6-6.
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The article puts forward the hypothesis about the wave nature of pension systems reforms since the early 1990 under the effect of demographic and economic factors. In response to the results of previous works on this subject and statistical analysis results, wave’s mechanism has been identified. Conditions for starting the wave of pension reforms established with long-term demographic trend in periods of tension (the higher growth rates of age dependency ratio and others). The start and dynamic of the wave are determined by macroeconomic shocks arise from decreasing phase of business-cycle. The growth phase of pension reforms are followed by the period of deceleration. There is a factor that slowdowns responses to macroeconomic shocks (the decisions about pension reforms are not accepted instantly). Pension system adjusts to new conditions until further tightening. Quantitative and quality analysis of pension reforms across countries would allow to test this hypothesis. To that end an appropriate instruments have been developed: the classifier of pension reform (67 items with scoring system to estimate the depth of the changes), evaluation system for economic factors influences via sensitive to pension systems indicators and associated macroeconomic shocks. A cross-section of 24 countries generates a mix of pension reforms for the period of 1994–2019, two waves of pension reforms (1990–2008 and 2009 – present) is revealed, the hypothesis of waves nature of pension reforms is confirmed. The heart of pension systems transformations in the first way is identified. These are lowering of government pensions obligations, shifting the risks from state to population with the introduction of DCschemes. The suggestions that the implementation of second pillar is positive only for countries with well-developed financial market. The research of second-wave of pension reforms and projection of the third way will be dealt with in the next article.
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Boeglin, Werner, and Misak Sargsian. "Modern studies of the Deuteron: From the lab frame to the light front." International Journal of Modern Physics E 24, no. 03 (March 2015): 1530003. http://dx.doi.org/10.1142/s0218301315300039.
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We review the recent progress made in studies of deuteron structure at small internucleon distances. This progress is largely facilitated by the new generation of experiments in deuteron electrodisintegration carried out at unprecedentedly high momentum transfer. The theoretical analysis of these data confirms the onset of the high energy eikonal regime in the scattering process which allows one to separate long-range nuclear effects from the effects genuinely related to the short distance structure of the deuteron. Our conclusion is that for the first time the deuteron is probed at relative momenta beyond 300 MeV/c without dominating long-range effects. As a result, at these large nucleon momenta the cross-section is sensitive to the nuclear dynamics at subfermi distances. Due to large internal momenta involved we are dealing with the relativistic bound state that is best described by the light-cone momentum distribution of nucleons in the deuteron. We present the first attempt of extracting the deuteron light-cone momentum distribution function from data and discuss the importance of this quantity for studies of quantum chromodynamics (QCD) structure of the bound nucleon in deep inelastic scattering (DIS) off the deuteron. We conclude the review giving an outlook of the next generation of high energy experiments which will extend our reach to much smaller distances in the deuteron.
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Altenburg, T. M., H. Degens, W. van Mechelen, A. J. Sargeant, and A. de Haan. "Recruitment of single muscle fibers during submaximal cycling exercise." Journal of Applied Physiology 103, no. 5 (November 2007): 1752–56. http://dx.doi.org/10.1152/japplphysiol.00496.2007.
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In literature, an inconsistency exists in the submaximal exercise intensity at which type II fibers are activated. In the present study, the recruitment of type I and II fibers was investigated from the very beginning and throughout a 45-min cycle exercise at 75% of the maximal oxygen uptake, which corresponded to 38% of the maximal dynamic muscle force. Biopsies of the vastus lateralis muscle were taken from six subjects at rest and during the exercise, two at each time point. From the first biopsy single fibers were isolated and characterized as type I and II, and phosphocreatine-to-creatine (PCr/Cr) ratios and periodic acid-Schiff (PAS) stain intensities were measured. Cross sections were cut from the second biopsy, individual fibers were characterized as type I and II, and PAS stain intensities were measured. A decline in PCr/Cr ratio and in PAS stain intensity was used as indication of fiber recruitment. Within 1 min of exercise both type I and, although to a lesser extent, type II fibers were recruited. Furthermore, the PCr/Cr ratio revealed that the same proportion of fibers was recruited during the whole 45 min of exercise, indicating a rather constant recruitment. The PAS staining, however, proved inadequate to fully demonstrate fiber recruitment even after 45 min of exercise. We conclude that during cycling exercise a greater proportion of type II fibers is recruited than previously reported for isometric contractions, probably because of the dynamic character of the exercise. Furthermore, the PCr/Cr ratio method is more sensitive in determining fiber activation than the PAS stain intensity method.
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Bagheri-Sadeghi, Nojan, Brian T. Helenbrook, and Kenneth D. Visser. "Ducted wind turbine optimization and sensitivity to rotor position." Wind Energy Science 3, no. 1 (April 25, 2018): 221–29. http://dx.doi.org/10.5194/wes-3-221-2018.
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Abstract. The design of a ducted wind turbine modeled using an actuator disc was studied using Reynolds-averaged Navier–Stokes (RANS) computational fluid dynamics (CFD) simulations. The design variables included the rotor thrust coefficient, the angle of attack of the duct cross section, the radial gap between the rotor and the duct, and the axial location of the rotor in the duct. Two different power coefficients, the rotor power coefficient (based on the rotor swept area) and the total power coefficient (based on the exit area of the duct), were used as optimization objectives. The optimal value of thrust coefficients for all designs was nearly constant, having a value between 0.9 and 1. The rotor power coefficient was sensitive to rotor gap but was insensitive to the rotor's axial location for positions ranging from upstream of the throat to nearly half the distance down the duct. Compared to the design that maximized rotor power coefficient, the design for maximal total power coefficient was characterized by a smaller angle of attack, a smaller rotor gap, and a downstream placement of the rotor. The insensitivity of power output to the rotor position implies that a rotor placed further downstream in the duct could produce the same power with a considerably smaller duct exit area and thus a greater total power coefficient. The design for that maximized total power coefficient exceeded Betz's limit with a total power coefficient of 0.67.
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Reimer, L. "Energy-filtering Transmission Electron Microscopy in materials and life science." Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 936–37. http://dx.doi.org/10.1017/s0424820100172413.
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Energy-filtering transmission electron microscopy can be realized by an imaging filter lens in thecolumn of a TEM, a post-column electron energy-loss spectrometer or a dedicated STEM. This offers new possibilities in analytical electron microscopy by combining the operation modes of electron-spectroscopic imaging (ESI), electron-spectroscopic diffraction (ESD) and the record of an electron energy-loss spectrum (EELS).ESI can be used in the zero-loss mode to remove all inelastically scattered electrons. Thicker amorphous and crystalline specimens can be observed without chromatic aberration and with a transmissionof 10−3 up to 80(110) and 150(200) μg/cm2 at 80(120) keV, respectively. This results in a condiserable increase of scattering, phase and Bragg contrast, especially for low Z material because the ratio of inelastic-to-elastic cross section increases as 20/Z with decreasing atomic number. In future energy-filtered high-resolution crystal-lattice images will offer us a better comparison with dynamical simulations. Plasmon loss filtering can be applied for a better separation of phases (e.g. precipitates in a matrix), which differ in their plasmon loss by about 1 eV. Owing to intersections of the energy loss spectra, different parts of a specimen can change their contrast when tuning the selected energy window. Structures containing non carbon atoms will beconsiderably increased in a bright field like contrast relative to the carboneous matrix just below the carbon K edge (structure—sensitive imaging).
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ORTONA, GIACOMO. "OPEN CHARM ANALYSIS ON THE FIRST PP COLLISIONS AT $\sqrt{s} = 7~{\rm TeV}$ WITH ALICE." International Journal of Modern Physics: Conference Series 02 (January 2011): 25–30. http://dx.doi.org/10.1142/s201019451100081x.
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A Large Ion Collider Experiment (ALICE) is one of the four large experiments at the Large Hadron Collider (LHC), and the one dedicated to ultra relativistic heavy ion collisions, aiming at investigating the properties of the high-density state of QCD matter produced in such events. ALICE started to collect data in proton-proton collisions at the LHC at CERN in November 2009 (with a centre of mass energy [Formula: see text]). Since March 2010 data are being recorded at an energy of [Formula: see text] while from November 7 to December 6 LHC provided Pb-Pb collisions at an energy of [Formula: see text] per nucleon-nucleon pair. In Pb-Pb collisions heavy quarks are regarded as sensitive probes of the interaction dynamics between the parton and medium produced in the collisions, and the energies available at LHC will allow to study the production of heavy flavours with high statistics. Proton-proton data will be used to measure the heavy flavours production cross section to compare with perturbative QCD calculations in an unexplored energy domain and they will provide the reference for the study of Pb-Pb collisions. After a description of the ALICE experiment focused on its heavy flavour related performance, the status of the first analysis on charm production, measured by reconstructing the decays of D0, D+, D*+, and Ds into hadronic and semi-leptonic channels will be presented. An outlook of the same measurements for the upcoming Pb-Pb run will also be discussed.
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TOKUDA, ISAO, RYUJI TOKUNAGA, and KAZUYUKI AIHARA. "A SIMPLE GEOMETRICAL STRUCTURE UNDERLYING SPEECH SIGNALS OF THE JAPANESE VOWEL /a/." International Journal of Bifurcation and Chaos 06, no. 01 (January 1996): 149–60. http://dx.doi.org/10.1142/s0218127496001892.
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We provide several pieces of evidence for possible chaotic dynamics in the irregular behavior of normal speech signals of the Japanese vowel /a/. First, principal component analysis demonstrates that a simple geometric structure underlying the complex speech signal is well reconstructed in a three-dimensional delay-coordinate space. Observations of the reconstructed speech trajectory at multiple cross sections also display speech dynamics with stretching, folding and compressing. Second, Lyapunov spectrum analysis indicates sensitive dependence on initial conditions with a positive Lyapunov exponent for the speech signals of several different speakers. Third, nonlinear modeling analysis with an artificial neural network shows that the nonlinear dynamics of the vowel sound is well reproduced by a deterministic dynamical model.
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Pozo, Jose M., Arjan J. Geers, Maria-Cruz Villa-Uriol, and Alejandro F. Frangi. "Flow complexity in open systems: interlacing complexity index based on mutual information." Journal of Fluid Mechanics 825 (July 21, 2017): 704–42. http://dx.doi.org/10.1017/jfm.2017.392.
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Flow complexity is related to a number of phenomena in science and engineering and has been approached from the perspective of chaotic dynamical systems, ergodic processes or mixing of fluids, just to name a few. To the best of our knowledge, all existing methods to quantify flow complexity are only valid for infinite time evolution, for closed systems or for mixing of two substances. We introduce an index of flow complexity coined interlacing complexity index (ICI), valid for a single-phase flow in an open system with inlet and outlet regions, involving finite times. ICI is based on Shannon’s mutual information (MI), and inspired by an analogy between inlet–outlet open flow systems and communication systems in communication theory. The roles of transmitter, receiver and communication channel are played, respectively, by the inlet, the outlet and the flow transport between them. A perfectly laminar flow in a straight tube can be compared to an ideal communication channel where the transmitted and received messages are identical and hence the MI between input and output is maximal. For more complex flows, generated by more intricate conditions or geometries, the ability to discriminate the outlet position by knowing the inlet position is decreased, reducing the corresponding MI. The behaviour of the ICI has been tested with numerical experiments on diverse flows cases. The results indicate that the ICI provides a sensitive complexity measure with intuitive interpretation in a diversity of conditions and in agreement with other observations, such as Dean vortices and subjective visual assessments. As a crucial component of the ICI formulation, we also introduce the natural distribution of streamlines and the natural distribution of world-lines, with invariance properties with respect to the cross-section used to parameterize them, valid for any type of mass-preserving flow.
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Nemirovsky, Y. V., and A. V. Mishchenko. "Dynamic analysis of composite rods with variable cross-section." Computational Continuum Mechanics 8, no. 2 (2015): 188–99. http://dx.doi.org/10.7242/1999-6691/2015.8.2.16.
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Eisenberger, Moshe. "Dynamic stiffness matrix for variable cross-section Timoshenko beams." Communications in Numerical Methods in Engineering 11, no. 6 (June 1995): 507–13. http://dx.doi.org/10.1002/cnm.1640110605.
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Zhang, Xin, Yi Quan Xu, Kai Meng, and Qing Guan Chen. "Dynamic Detection and Analysis of Raw Silk’s Flatness." Advanced Materials Research 175-176 (January 2011): 385–88. http://dx.doi.org/10.4028/www.scientific.net/amr.175-176.385.
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The shape of most raw silk’s cross-section can be regarded as ellipse approximately. Axial length of the raw silk’s cross-section was detected and recorded dynamically by photoelectric sensor combined with the software of LabVIEW. Two photoelectric sensors were located orthogonally to measure axial lengths of the ellipse. The major and minor values can be considered as the major and minor axis values of the raw silk’s elliptical cross-section respectively. Thereby, the flatness and the area of raw silk’s cross-section can be calculated according to the values of major and minor axes. In addition, the raw silk’s evenness was characterized based on the variation of the cross-sectional area.
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Jablonski, A. "Transport cross section for electrons at energies of surface-sensitive spectroscopies." Physical Review B 58, no. 24 (December 15, 1998): 16470–80. http://dx.doi.org/10.1103/physrevb.58.16470.
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Grigoriev, A. V., O. A. Rudakov, and A. V. Solovieva. "Gas dynamic calculation of detonation in variable cross-section ducts." VESTNIK of Samara University. Aerospace and Mechanical Engineering 18, no. 1 (April 16, 2019): 42–54. http://dx.doi.org/10.18287/2541-7533-2019-18-1-42-54.
Full textAbstract:
Formulas of gas dynamic calculation of detonation parameters in variable cross-section ducts are presented and a design detonation diagram is given. The diagram shows the detonation characteristics of super-compressed detonation and under-compressed detonation as the function of shock wave specific speed depending on the intensity of temperature of the ideal gas in a subsonic one-dimensional flow behind the shock wave propagating in a chemically active air-fuel mixture and on the ratio of geometrical expansion (convergence) of the duct. The propagation of a stationary shock-wave the static pressure of which in the output cross-section of the expanded duct is equal to atmospheric pressure is referred to as design detonation. This means that all the energy of the shock wave at the output of the duct can be converted into polytropic work function of gas expansion in a detonation engine. Otherwise, if the flow takes place in the mode of overexpansion due to the separation of the compressive shock wave inside the duct or in the case of insufficient expansion part of the shock wave energy will be lost. The total impulse equation for a geometrically expanding duct is solved by replacing the integral describing the thrust force with the average integral value of the curve of the static pressure acting on the side wall of the expanding duct. The frictional force is neglected due to its insignificant value. It is shown that the presence of an insufficiently compressed shock wave is not possible as the shock wave moving at the supersonic speed in the convergent duct will be decelerated to the sonic speed. To stabilize it additional heat should be supplied to transform the convergent duct behind the compressive shock wave into a semi-permanent cross-section duct wherein thermal crisis stabilizing the shock wave can be achieved. The minimum value of the detonation pipe diameter of 50 mm is substantiated. Below that value sharp reduction of combustion efficiency takes place. The results of the work can be used for the computation of detonation engine thermodynamic cycle parameters.
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Grigoriev, A. V., O. A. Rudakov, and A. V. Solovieva. "Gas dynamic calculation of detonation in constant-cross-section ducts." VESTNIK of Samara University. Aerospace and Mechanical Engineering 18, no. 3 (October 31, 2019): 48–58. http://dx.doi.org/10.18287/2541-7533-2019-18-3-48-58.
Full textAbstract:
The paper presents a computational method with the use of gas-dynamic functions of parameters of detonation in a one-dimensional subsonic flow of ideal gas behind the shock wave propagating in chemically active air-and-fuel mixture in a uniform-cross-section duct, where the resultant of normal pressure forces acting on its side surface is equal to zero. Stabilization of the shock wave is provided by the onset of thermal crisis with the air-and-fuel mixture combustion heat supply to the gas behind the wave. In this case the value of the specific speed of the combustion products is equal to the critical one. The solution of the total-impulse equation considering the above mentioned peculiarities of the flow in a uniform-cross-section duct establishes clear correlation of the specific speed of the stabilized shock wave to the rate of rise of the temperature of the gas behind it, which gives an opportunity to determine all detonation parameters. The shock wave can be initiated by the detonation of an explosive substance and carries a huge amount of energy. It is shown that the shock wave can be obtained only if the source of small disturbances itself moves at the supersonic speed. It is shown that total pressure behind the shock wave decreases significantly and the entropy increases due to the wave losses, whereas the static pressure increases significantly. An explanation of this effect is given. A formula for calculating the rate of gas temperature rise was derived as a function of the specific speed of the shock wave, the air-and-fuel mixture heat value and the heat availability factor that designates the dissociation of the combustion products and heat loss through the duct wall under specified initial conditions. The reliability of the method of calculating detonation was experimentally substantiated. The work is currently important for the evaluation of the detonation engine efficiency.
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Kim, Sung-Kyun, and Oh-Seop Song. "Dynamic Response Analysis of Composite H-type Cross-section Beams." Transactions of the Korean Society for Noise and Vibration Engineering 20, no. 6 (June 20, 2010): 583–92. http://dx.doi.org/10.5050/ksnve.2010.20.6.583.
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