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1
Kevlahan, N. K. R. "The propagation of weak shocks in non-uniform flows". Journal of Fluid Mechanics 327 (25 novembre 1996): 161–97. http://dx.doi.org/10.1017/s0022112096008506.
Testo completoAbstract (sommario):
A new theory of the propagation of weak shocks into non-uniform, two-dimensional flows is introduced. The theory is based on a description of shock propagation in terms of a manifold equation together with compatibility conditions for shock strength and its normal derivatives behind the shock. This approach was developed by Ravindran & Prasad (1993) for shocks of arbitrary strength propagating into a medium at rest and is extended here to non-uniform media and restricted to moderately weak shocks. The theory is tested against known analytical solutions for cylindrical and plane shocks, and against a full direct numerical simulation (DNS) of a shock propagating into a sinusoidal shear flow. The test against DNS shows that the present theory accurately predicts the evolution of a moderately weak shock front, including the formation of shock-shocks due to shock focusing. The theory is then applied to the focusing of an initially parabolic shock, and to the propagation of an initially straight shock into a variety of simple flows (sinusoidal shear, vortex array, point-vortex array) exhibiting some fundamental properties of turbulent flows. A number of relations are deduced for the variation of shock quantities with initial shock strength MS0 and the Mach number of the flow ahead of the shock MU (e.g. separation of shock-shocks and maximum shock strength at a focus). It is found that shock-shocks are likely to form in turbulent flows with Mt/M1N > 0.14–0.25, where Mt is the average Mach number of the turbulence and M1N is the Mach number of the shock in a flow at rest. The shock moves up to 1.5% faster in a two-dimensional vortex array than in uniform flow.
2
GAVRILYUK, S. L., e R. SAUREL. "Rankine–Hugoniot relations for shocks in heterogeneous mixtures". Journal of Fluid Mechanics 575 (marzo 2007): 495–507. http://dx.doi.org/10.1017/s0022112006004496.
Testo completoAbstract (sommario):
The conservation of mass, momentum and energy are not sufficient to close a system of jump relations for shocks propagating in a heterogeneous mixture of compressible fluids. We propose here a closed set of relations corresponding to a two-stage structure of shock fronts. At the first stage, microkinetic energy due to the relative motion of mixture components is produced at the shock front. At the second stage, this microkinetic energy disappears inducing strong variations in the thermodynamical states that reach mechanical equilibrium. The microkinetic energy produced at the shock front is estimated by using an idea developed earlier for turbulent shocks in compressible fluids. The relaxation zone between the shocked state and the equilibrium state is integrated over a thermodynamic path a justification of which is provided. Comparisons with experiments on shock propagation in a mixture of condensed materials confirm the proposed theory.
3
Hesselink, Lambertus, e Bradford Sturtevant. "Propagation of weak shocks through a random medium". Journal of Fluid Mechanics 196 (novembre 1988): 513–53. http://dx.doi.org/10.1017/s0022112088002800.
Testo completoAbstract (sommario):
The propagation of weak shock waves (Ms = 1.007, 1.03 and 1.1) through a statistically uniform random medium has been investigated experimentally in a shock tube. The wave-from geometry, rise time and amplitude of initially plane shocks which have propagated through a random mixture of helium and refrigerant 12 are measured. The effect of shock propagation on the properties of the random medium is visualized with schlieren and shadow photography. The pressure histories of the distorted shock waves reflecting from a normal end wall are observed to be both peaked and rounded. In the rounded case the perturbed shock is found to be made up of a succession of weak, slightly curved fronts with a total effective rise time orders of magnitude greater than the classical Taylor thickness. The radius of curvature of the weakest shocks after propagating through the random medium is inferred from observations at two downstream stations to be about 7 times the integral scale of the gas inhomogeneities. It is concluded that the observed distortions of the wave fronts can best be explained in terms of random focusing and defocusing of the front by the inhomogeneities in the medium. A ray-tracing calculation has been used to interpret the experimental observations. It is found that geometrical considerations are sufficient to account for many of the effects observed on the shocks.
4
Erkaev, N. V., V. A. Shaidurov, V. S. Semenov e H. K. Biernat. "Effects of MHD slow shocks propagating along magnetic flux tubes in a dipole magnetic field". Nonlinear Processes in Geophysics 9, n. 2 (30 aprile 2002): 163–72. http://dx.doi.org/10.5194/npg-9-163-2002.
Testo completoAbstract (sommario):
Abstract. Variations of the plasma pressure in a magnetic flux tube can produce MHD waves evolving into shocks. In the case of a low plasma beta, plasma pressure pulses in the magnetic flux tube generate MHD slow shocks propagating along the tube. For converging magnetic field lines, such as in a dipole magnetic field, the cross section of the magnetic flux tube decreases enormously with increasing magnetic field strength. In such a case, the propagation of MHD waves along magnetic flux tubes is rather different from that in the case of uniform magnetic fields. In this paper, the propagation of MHD slow shocks is studied numerically using the ideal MHD equations in an approximation suitable for a thin magnetic flux tube with a low plasma beta. The results obtained in the numerical study show that the jumps in the plasma parameters at the MHD slow shock increase greatly while the shock is propagating in the narrowing magnetic flux tube. The results are applied to the case of the interaction between Jupiter and its satellite Io, the latter being considered as a source of plasma pressure pulses.
5
Watari, S., e T. Detman. "In situ local shock speed and transit shock speed". Annales Geophysicae 16, n. 4 (30 aprile 1998): 370–75. http://dx.doi.org/10.1007/s00585-998-0370-9.
Testo completoAbstract (sommario):
Abstract. A useful index for estimating the transit speeds was derived by analyzing interplanetary shock observations. This index is the ratio of the in situ local shock speed and the transit speed; it is 0.6–0.9 for most observed shocks. The local shock speed and the transit speed calculated for the results of the magnetohydrodynamic simulation show good agreement with the observations. The relation expressed by the index is well explained by a simplified propagation model assuming a blast wave. For several shocks the ratio is approximately 1.2, implying that these shocks accelerated during propagation in slow-speed solar wind. This ratio is similar to that for the background solar wind acceleration.Keywords. Interplanetary physics (Flare and stream dynamics; Interplanetary shocks; Solar wind plasma)
6
Cook, David. "Real Propagation of Monetary Shocks: Dynamic Complementarities and Capital Utilization". Macroeconomic Dynamics 3, n. 3 (settembre 1999): 368–83. http://dx.doi.org/10.1017/s1365100599012043.
Testo completoAbstract (sommario):
This paper studies the dynamic propagation of a liquidity shock through two real propagation channels: dynamic complementarities and time-varying capital utilization. The findings for an economy with intertemporal externalities are: (1) An otherwise transient liquidity shock will have real effects on output for several years; (2) time-varying capital utilization strongly augments this propagation; (3) the real effects of monetary shocks last longer when external productivity depreciates faster; and (4) nominal prices respond more sluggishly to a change in the money supply when there is a strong real propagation channel.
7
Tenorio-Tagle, Guillermo. "On the Formation and Propagation of Interstellar Jets". International Astronomical Union Colloquium 120 (1989): 264–75. http://dx.doi.org/10.1017/s0252921100023848.
Testo completoAbstract (sommario):
Summary.The flow that results from stationary supersonically converging conical streams is studied by means of two dimensional numerical calculations. Convcrgency leads to a “colimator” conical shock and this to the formation of an underexpanded hydrodynamical jet. The properties of the conical shock and of the collimated stream are summarized for a variety of initial conditions. The resultant jets are followed to large distances (≥ 7.5X1017 cm) away from the injection point, and are shown to develop a complicated structure that eventually approaches a stationary state. Stationary features such as crossing shocks are shown to evolve from working surface shocks, left behind the head of the jet to ensure self-collimation of the beam matter.
8
Xu, Y. F., S. C. Hu, Y. Cai e S. N. Luo. "Origins of plastic shock waves in single-crystal Cu". Journal of Applied Physics 131, n. 11 (21 marzo 2022): 115901. http://dx.doi.org/10.1063/5.0080757.
Testo completoAbstract (sommario):
We investigate shock wave propagation in single-crystal Cu with large-scale molecular dynamics simulations. Plastic shock waves propagate via dislocation nucleation or growth. With decreasing particle velocity, a remarkable drop in plastic shock wave velocity relative to the linear shock velocity–particle velocity relation is observed in the elastic–plastic two-wave regime for different loading directions. This reduction can be attributed to the changes in the mechanisms of plastic shock wave generation/propagation, from the dislocation nucleation-dominant mode, to the alternating nucleation and growth mode, and to the growth-dominant mode. For weak shocks, the plastic shock advances at the speed of the growth of existing dislocations (below the maximum elastic shock wave speed), considerably slower than the dislocation nucleation front for strong shocks (above the maximum elastic shock wave speed).
9
Ohmura, Takumi, Mami Machida, Kenji Nakamura, Yuki Kudoh, Yuta Asahina e Ryoji Matsumoto. "Two-Temperature Magnetohydrodynamics Simulations of Propagation of Semi-Relativistic Jets". Galaxies 7, n. 1 (11 gennaio 2019): 14. http://dx.doi.org/10.3390/galaxies7010014.
Testo completoAbstract (sommario):
In astrophysical jets observed in active galactic nuclei and in microquasars, the energy exchange rate by Coulomb collision is insufficient for thermal equilibrium between ions and electrons. Therefore, it is necessary to consider the difference between the ion temperature and the electron temperature. We present the results of two-temperature magnetohydrodynamics(MHD) simulations to demonstrate the effects of Coulomb coupling. It is assumed that the thermal dissipation heats only ions. We find that the ion and electron temperatures are separated through shocks. Since the ion entropy is increased by energy dissipation at shocks and the Coulomb collisions are inefficient, electron temperature becomes about 10 times lower than the ion temperature in the hotspot ahead of the jet terminal shock. In the cocoon, electron temperature decreases by gas mixing between high temperature cocoon gas and low temperature shocked-ambient gas even when we neglect radiative cooling, but electrons can be heated through collisions with ions. Radiation intensity maps are produced by post processing numerical results. Distributions of the thermal bremsstrahlung radiation computed from electron temperature have bright filament and cavity around the jet terminal shock.
10
MONICA, A., e PHOOLAN PRASAD. "Propagation of a curved weak shock". Journal of Fluid Mechanics 434 (10 maggio 2001): 119–51. http://dx.doi.org/10.1017/s0022112001003731.
Testo completoAbstract (sommario):
Propagation of a curved shock is governed by a system of shock ray equations which is coupled to an infinite system of transport equations along these rays. For a two-dimensional weak shock, it has been suggested that this system can be approximated by a hyperbolic system of four partial differential equations in a ray coordinate system, which consists of two independent variables (ζ, t) where the curves t = constant give successive positions of the shock and ζ = constant give rays. The equations show that shock rays not only stretch longitudinally due to finite amplitude on a shock front but also turn due to a non-uniform distribution of the shock strength on it. These changes finally lead to a modification of the amplitude of the shock strength. Since discontinuities in the form of kinks appear on the shock, it is necessary to study the problem by using the correct conservation form of these equations. We use such a system of equations in conservation form to construct a total-variation-bounded finite difference scheme. The numerical solution captures converging shock fronts with a pair of kinks on them – the shock front emerges without the usual folds in the caustic region. The shock strength, even when the shock passes through the caustic region, remains so small that the small-amplitude theory remains valid. The shock strength ultimately decays with a well-defined geometrical shape of the shock front – a pair of kinks which separate a central disc from a pair of wings on the two sides. We also study the ultimate shape and decay of shocks of initially periodic shapes and plane shocks with a dent and a bulge.
11
Lkhagvadorj, Munkhjargal, Gábor Facskó, Andrea Opitz, Péter Kovács e David G. Sibeck. "Propagation of Interplanetary Shocks in the Inner Heliosphere". Astrophysical Journal 980, n. 1 (7 febbraio 2025): 137. https://doi.org/10.3847/1538-4357/ad9d12.
Testo completoAbstract (sommario):
Abstract Interplanetary (IP) shocks are one of the crucial dynamic phenomena in the heliosphere. They can accelerate particles to high energies, generate plasma waves, and trigger geomagnetic storms in Earth’s magnetosphere, significantly impacting technological infrastructure. In this study, two IP shock events are selected to study the temporal variations of the shock parameters using magnetometer and ion plasma measurements from STEREO-A and B, the Wind, Cluster fleet, and the Advanced Composition Explorer spacecraft. The shock normal vectors are determined using minimum variance analysis and magnetic coplanarity methods. During the 2007 May 7 event, the shock parameters and the shock normal direction remain consistent across each spacecraft crossing of the shock. The shock surface appears to be tilted by almost the same degree as the Parker spiral, and the driver could be a corotating interaction region (CIR). During the 2007 April 23 event, the shock parameters do not change significantly except for the shock angle θ Bn ; however, the shape of the IP shock appears to be twisted in the direction perpendicular to the Sun–Earth line as well. The driver of this rippled shock is a stream interaction region/CIR as well.
12
Manzo, Gerardo, e Antonio Picca. "The Impact of Sovereign Shocks". Management Science 66, n. 7 (luglio 2020): 3113–32. http://dx.doi.org/10.1287/mnsc.2019.3326.
Testo completoAbstract (sommario):
This paper studies the dynamic propagation mechanisms of systemic risk shocks within and across macrosystems of governments and financial institutions. We propose a novel approach to identify relevant systemic shocks and to classify them into sovereign or banking categories. We find that sovereign shocks have a significant and persistent impact on the probability of a collective banking default. We also explore channels through which these shocks propagate and identify how sovereign fiscal fragility and banking exposure are relevant mechanisms of shock transmission. This paper was accepted by Gustavo Manso, finance.
13
INOUE, YOSHINORI, e TAKERU YANO. "Propagation of strongly nonlinear plane N-waves". Journal of Fluid Mechanics 341 (25 giugno 1997): 59–76. http://dx.doi.org/10.1017/s0022112097005405.
Testo completoAbstract (sommario):
Formation and evolution of N (-like) waves is studied without the restriction of low amplitude, namely weak nonlinearity. To this end, the classical piston problem of gasdynamics is investigated, in which the wave is radiated by a piston executing a single cycle of harmonic oscillation into an inviscid perfect gas. The method of analysis is based on the simple-wave theory up to the shock formation time, and beyond that time on the numerical calculation by a high-resolution TVD upwind scheme. The initial sinusoid-like wave profile is rapidly distorted as the wave propagates, and this leads to the formation of head and tail shocks. The main effects of strong nonlinearity may be listed as follows: (i) entropy production at shock fronts, (ii) the existence of waves reflected from shocks, (iii) an asymmetric wave profile stemming from the boundary condition at the source of the strongly nonlinear problem. As the result, the strongly nonlinear wave possesses the following remarkable distinctive features, in contrast to its counterpart in the weakly nonlinear regime. The tail shock is not formed at the tail of the wave, and the expansion wave behind the head shock has non-uniform intensity. The N (-like) wave propagates with some excess mass. Thereby a region with low density, associated with the entropy production, appears in the vicinity of the source.
14
Salisu, Afees A., Rangan Gupta e Idris A. Adediran. "The Effect of US Uncertainty Shock on International Equity Markets: The Role of the Global Financial Cycle". Review of Economic Analysis 15, n. 2 (26 giugno 2023): 139–59. http://dx.doi.org/10.15353/rea.v15i2.5213.
Testo completoAbstract (sommario):
We contribute to the literature on the international propagation of uncertainty shocks with a Global Vector Autoregressive (GVAR) model that quantifies the spillover effects of uncertainty shocks in the US on to real equity prices of 32 advanced and emerging countries (besides the US). In this regard, we also account for the role of global financial market conditions in the propagation of these shocks, using high and low values of the Global Financial Cycle (GFCy) index. Using quarterly data over 1980:1 to 2019:2, our findings reveal greater response of advanced markets than emerging counterparts to an US uncertainty shock. Further, we show consistent higher negative responses during weak financial conditions than otherwise, confirming the intervening role of the GFCy index. Our results have important implications for investors and policymakers.
15
Kinnan, Cynthia, Krislert Samphantharak, Robert Townsend e Diego Vera-Cossio. "Propagation and Insurance in Village Networks". American Economic Review 114, n. 1 (1 gennaio 2024): 252–84. http://dx.doi.org/10.1257/aer.20220892.
Testo completoAbstract (sommario):
Firms in developing countries are embedded in supply chains and labor networks. These linkages may propagate or attenuate shocks. Using panel data from Thai villages, we document three facts: as households facing idiosyncratic shocks adjust their production, these shocks propagate to other households on both the production and consumption sides; propagation is greater via labor than supply chain links; and shocks in denser networks and to more central households propagate more, while access to formal or informal insurance reduces propagation. Social benefits from expanding safety nets may be higher than private benefits. (JEL D13, D22, G22, I10, L14, L26, O10)
16
Bisnovatyi-Kogan, G. S., e S. A. Silich. "Thin Layer Approximation in 3-D". International Astronomical Union Colloquium 166 (1997): 137–40. http://dx.doi.org/10.1017/s025292110007086x.
Testo completoAbstract (sommario):
AbstractEquations are derived which describe the propagation of strong shocks in the interstellar matter, without any restrictions for symmetry, in a thin layer approximation (2.5 dimensions). Using these equations permits to calculate the propagation of shock waves from nonsymmetric supernovae explosions in a medium with arbitrary density distribution and the formation of superbubbles in galaxies.
17
Liao, Yihan. "Microeconomic Shock Propagation Through Production Networks in China". Mathematics 13, n. 3 (23 gennaio 2025): 359. https://doi.org/10.3390/math13030359.
Testo completoAbstract (sommario):
The question of whether microeconomic shocks induce aggregate fluctuations constitutes a central issue in economic research. This paper introduces a general equilibrium model with production networks to explore the propagation mechanisms of microeconomic shocks. A novel triangular production network structure is introduced, and simulations are performed using China’s input-output table to analyze the propagation of these shocks within the Chinese economy. The model demonstrates that the first-order effects of microeconomic shocks propagate downstream along the industrial chain, while the second-order effects of microeconomic productivity shocks propagate both upstream and downstream along the chain. The first-order propagation mechanism of microeconomic shocks involves changes in prices within the affected sector and its downstream sectors. Additionally, the second-order effects of microeconomic shocks rely on the reallocation of factors. The simulation results indicate that China’s production network matrix is triangular, and that the financial sector plays a crucial role in amplifying the effects of microeconomic shocks. Government should prioritize supporting upstream fundamental sectors to mitigate the adverse impacts of external shocks on economic fluctuations and to address systemic financial risks.
18
Shanmugaraju, A., e S. Umapathy. "On the Possibility of Radio Emission from Quasi-parallel and Quasi-perpendicular Propagation of Shocks". International Astronomical Union Colloquium 179 (2000): 259–62. http://dx.doi.org/10.1017/s0252921100064629.
Testo completoAbstract (sommario):
AbstractA set of 21 solar type II radio bursts observed using Hiraiso radio spectrograph have been analysed to study the direction of propagation of coronal shocks. A simple analysis is carried out to find the approximate angle between the shock normal and magnetic field by solving the Rankine-Hugoniot MHD relation with assumption of Alfven speed and plasma beta. From this analysis, it is suggested that both quasi-parallel shocks (favourable) and quasi-perpendicular shocks can generate type II bursts depending upon the circumstances of the corona.
19
Wu, Chin-Chun, Kan Liou, Brian E. Wood e Lynn Hutting. "Effects of Background Solar Wind and Drag Force on the Propagation of Coronal-mass-ejection-driven Shocks". Astrophysical Journal 977, n. 2 (1 dicembre 2024): 212. https://doi.org/10.3847/1538-4357/ad88ee.
Testo completoAbstract (sommario):
Abstract The propagation of interplanetary shocks, particularly those driven by coronal mass ejections (CMEs), is still an outstanding question in heliophysics and space weather forecasting. Here, we address the effects of the ambient solar wind on the propagation of two similar CME-driven shocks from the Sun to Earth. The two shock events (CME03, 2010 April 3; CME12, 2012 July 12) have the following properties. Both events (1) were driven by a halo CME (i.e., the source location is near the Sun–Earth line); (2) had a CME source in the southern hemisphere; (3) had a similar transit time (∼2 days) to Earth; (4) occurred in a nonquiet solar period; and (5) led to a severe geomagnetic storm. The initial (near the Sun) propagation speed, as measured by coronagraph images, was slower (by ∼300 km s−1) for CME03 than CME12, but it took about the same amount of traveling time for both events to reach Earth. According to the in situ solar wind observations from the Wind spacecraft, the CME03-driven shock was associated with a faster solar wind upstream of the shock than the CME12-driven shock. This is also demonstrated in our global MHD simulations. Analysis of our simulation result indicates that the drag force indirectly plays an important role in the shock propagation. The present study suggests that in addition to the initial CME propagation speed near the Sun, the shock speed (in the inertial frame) and the ambient solar wind conditions—in particular, the solar wind speed—are key to timing the arrival of CME-driven shock events.
20
Dzhambova, Krastina. "Estimating the dynamics of fiscal financing in emerging economies". Economic Analysis Letters 3, n. 1 (1 settembre 2023): 16–29. http://dx.doi.org/10.58567/eal03010003.
Testo completoAbstract (sommario):
I present a theoretical model and an empirical approach for jointly estimating the effectiveness of fiscal policy and the stochastic process of sovereign interest rate shocks. The theoretical model has features relevant to small open and emerging economies. Interest rate shocks affect the ability of firms to finance payroll expenses. This theoretical feature creates a propagation mechanism for interest rate shocks and affects government spending multipliers. This paper proposes a strategy for jointly estimating government spending multipliers and the interest rate shock process parameters.
21
Andria, Joseph, Giacomo di Tollo e Jaan Kalda. "Propagation of Bankruptcy Risk over Scale-Free Economic Networks". Entropy 24, n. 12 (24 novembre 2022): 1713. http://dx.doi.org/10.3390/e24121713.
Testo completoAbstract (sommario):
The propagation of bankruptcy-induced shocks across domestic and global economies is sometimes very dramatic; this phenomenon can be modelled as a dynamical process in economic networks. Economic networks are usually scale-free, and scale-free networks are known to be vulnerable with respect to targeted attacks, i.e., attacks directed towards the biggest nodes of the network. Here we address the following question: to what extent does the scale-free nature of economic networks and the vulnerability of the biggest nodes affect the propagation of economic shocks? We model the dynamics of bankruptcies as the propagation of financial contagion across the banking sector over a scale-free network of banks, and perform Monte-Carlo simulations based on synthetic networks. In addition, we analyze the public data regarding the bankruptcy of US banks from the Federal Deposit Insurance Corporation. The dynamics of the shock propagation is characterized in terms of the Bank Failures Diffusion Index, i.e., the average number of new bankruptcies triggered by the bankruptcy of a single bank, and in terms of the Shannon entropy of the whole network. The simulation results are in-line with the empirical findings, and indicate the important role of the biggest banks in the dynamics of economic shocks.
22
Jin, Yi, e Qingyuan Zhang. "Cascading Failure Modeling for Circuit Systems Considering Continuous Degradation and Random Shocks Using an Impedance Network". Symmetry 16, n. 4 (17 aprile 2024): 488. http://dx.doi.org/10.3390/sym16040488.
Testo completoAbstract (sommario):
The reliability of circuit systems is primarily affected by cascading failures due to their complex structural and functional coupling. Causes of cascading failure during circuit operation include the continuous degradation process of components and external random shocks. Circuit systems can exhibit asymmetric structural changes and functional loss during cascading failure propagation due to the coupling of degradation and shock and their uncertainty effects. To tackle this issue, this paper abstracts the circuit into an impedance network and constructs a component failure behavior model that considers the correlation between degradation and shock. The interactions between soft and hard failure processes among different components are discussed. Two types of cascading failure propagation processes are described: slow propagation associated with continuous degradation and damage shock, and fast propagation due to fatal shock. Based on this, a cascading failure simulation algorithm is developed. This article presents a case study to demonstrate the proposed models and to analyze the reliability of a typical circuit system.
23
Maleckar, M. M., M. C. Woods, V. Y. Sidorov, M. R. Holcomb, D. N. Mashburn, J. P. Wikswo e N. A. Trayanova. "Polarity reversal lowers activation time during diastolic field stimulation of the rabbit ventricles: insights into mechanisms". American Journal of Physiology-Heart and Circulatory Physiology 295, n. 4 (ottobre 2008): H1626—H1633. http://dx.doi.org/10.1152/ajpheart.00706.2008.
Testo completoAbstract (sommario):
To fully characterize the mechanisms of defibrillation, it is necessary to understand the response, within the three-dimensional (3D) volume of the ventricles, to shocks given in diastole. Studies that have examined diastolic responses conducted measurements on the epicardium or on a transmural surface of the left ventricular (LV) wall only. The goal of this study was to use optical imaging experiments and 3D bidomain simulations, including a model of optical mapping, to ascertain the shock-induced virtual electrode and activation patterns throughout the rabbit ventricles following diastolic shocks. We tested the hypothesis that the locations of shock-induced regions of hyperpolarization govern the different diastolic activation patterns for shocks of reversed polarity. In model and experiment, uniform-field monophasic shocks of reversed polarities (cathode over the right ventricle is RV−, reverse polarity is LV−) were applied to the ventricles in diastole. Experiments and simulations revealed that RV− shocks resulted in longer activation times compared with LV− shocks of the same strength. 3D simulations demonstrated that RV− shocks induced a greater volume of hyperpolarization at shock end compared with LV− shocks; most of these hyperpolarized regions were located in the LV. The results of this study indicate that ventricular geometry plays an important role in both the location and size of the shock-induced virtual anodes that determine activation delay during the shock and subsequently affect shock-induced propagation. If regions of hyperpolarization that develop during the shock are sufficiently large, activation delay may persist until shock end.
24
Kaur, Rupinder, e Nareshpal Singh Saini. "Ion Acoustic Shocks in a Weakly Relativistic Ion-Beam Degenerate Magnetoplasma". Galaxies 9, n. 3 (6 settembre 2021): 64. http://dx.doi.org/10.3390/galaxies9030064.
Testo completoAbstract (sommario):
A theoretical investigation is carried out to study the propagation properties of ion acoustic shocks in a plasma comprising of positive inertial ions, weakly relativistic ion beam and trapped electrons in the presence of a quantizing magnetic field. By using the reductive perturbation technique, the Korteweg–de Vries-Burgers (KdVB) equation and oscillatory shocks solution are derived. The characteristics of such kinds of shock waves are examined and discussed in detail under suitable conditions for different physical parameters. The strength of the magnetic field, ion beam concentration and ion-beam streaming velocity have a great influence on the amplitude and width of the shock waves and oscillatory shocks. The results may be useful to study the characteristics of ion acoustic shock waves in dense astrophysical regions such as neutron stars.
25
den Haan, Wouter J., Garey Ramey e Joel Watson. "Job Destruction and Propagation of Shocks". American Economic Review 90, n. 3 (1 giugno 2000): 482–98. http://dx.doi.org/10.1257/aer.90.3.482.
Testo completoAbstract (sommario):
This paper considers propagation of aggregate shocks in a dynamic general-equilibrium model with labor-market matching and endogenous job destruction. Cyclical fluctuations in the job-destruction rate magnify the output effects of shocks, as well as making them much more persistent. Interactions between capital adjustment and the job-destruction rate play an important role in generating persistence. Propagation effects are shown to be quantitatively substantial when the model is calibrated using job-flow data. Incorporating costly capital adjustment leads to significantly greater propagation. (JEL E24, E32)
26
SCHWENDEMAN, DONALD W. "On converging shock waves of spherical and polyhedral form". Journal of Fluid Mechanics 454 (10 marzo 2002): 365–86. http://dx.doi.org/10.1017/s0022112001007170.
Testo completoAbstract (sommario):
The behaviour of converging spherical shock waves is considered using Whitham's theory of geometrical shock dynamics. An analysis of converging shocks whose initial shape takes the form of regular polyhedra is presented. The analysis of this problem is motivated by the earlier work on converging cylindrical shocks discussed in Schwendeman & Whitham (1987). In that paper, exact solutions were reported for converging polygonal shocks in which the initial shape re-forms repeatedly as the shock contracts. For the polyhedral case, the analysis is performed both analytically and numerically for an equivalent problem involving shock propagation in a converging channel with triangular cross-section. It is found that a repeating sequence of shock surfaces composed of nearly planar pieces develops, although the initial planar surface does not re-form, and that the increase in strength of the shock at each iterate in the sequence follows the same behaviour as for a converging spherical shock independent of the convergence angle of the channel. In this sense, the shocks are stable and the result is analogous to that found in the two-dimensional case. A numerical study of converging spherical shocks subject to smooth initial perturbations in strength shows a strong tendency to form surfaces composed of nearly planar pieces suggesting that the stability result is fairly general.
27
Hu, Youqiu. "Anisotropic propagation of flare-induced shocks". Chinese Science Bulletin 43, n. 5 (marzo 1998): 402–4. http://dx.doi.org/10.1007/bf02883719.
Testo completo
28
GOODMAN, JEREMY, e ANDREW MACFADYEN. "Ultra-relativistic geometrical shock dynamics and vorticity". Journal of Fluid Mechanics 604 (14 maggio 2008): 325–38. http://dx.doi.org/10.1017/s0022112008001249.
Testo completoAbstract (sommario):
Geometrical shock dynamics, also called CCW theory, yields approximate equations for shock propagation in which only the conditions at the shock appear explicitly; the post-shock flow is presumed approximately uniform and enters implicitly via a Riemann invariant. The non-relativistic theory, formulated by G. B. Whitham and others, matches many experimental results surprisingly well. Motivated by astrophysical applications, we adapt the theory to ultra-relativistic shocks advancing into an ideal fluid whose pressure is negligible ahead of the shock, but is one third of its proper energy density behind the shock. Exact results are recovered for some self-similar cylindrical and spherical shocks with power-law pre-shock density profiles. Comparison is made with numerical solutions of the full hydrodynamic equations. We review relativistic vorticity and circulation. In an ultra-relativistic ideal fluid, circulation can be defined so that it changes only at shocks, notwithstanding entropy gradients in smooth parts of the flow.
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Pitňa, Alexander, Jana Šafránková, Zdeněk Němeček, Gilbert Pi, Gary Zank, Lingling Zhao, Laxman Adhikari e Masaru Nakanotani. "Turbulent Heating of Solar Wind Plasma Downstream of Magnetohydrodynamic Shocks". Astrophysical Journal 963, n. 2 (1 marzo 2024): 161. http://dx.doi.org/10.3847/1538-4357/ad1c64.
Testo completoAbstract (sommario):
Abstract Interplanetary (IP) shocks are believed to play a significant role in both amplifying the background level of turbulent fluctuations and in heating the bulk solar wind (SW). This study investigates the thermodynamic properties downstream of IP shocks. We examine the temperature, density, and specific entropy changes in the shocked plasma, taking into consideration the geometric aspects of IP shock propagation within the expanding SW. Specifically, in our analysis, we account for the fact that any particular temporal range of one-point measurement may correspond to vastly different physically relevant temporal and/or spatial dimensions, such as the age of the shocked plasma and/or radial distance to the place where the plasma encountered the shock. Thus, our approach resolves the contradictions in previously reported temperature and specific entropy profiles in downstream regions and suggests that downstream regions exhibit greater turbulent heating compared to the pristine SW. This may contribute to the overall heating of the SW plasma. The paper presents a phenomenological parameter to predict specific entropy profiles and demonstrates the consistency of the proposed model with observations. We discuss the implications of these results for the thermodynamics of the SW beyond 1 au.
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McKenna-Lawlor, S. M. P., M. Dryer, Z. Smith, K. Kecskemety, C. D. Fry, W. Sun, C. S. Deehr, D. Berdichevsky, K. Kudela e G. Zastenker. "Arrival times of Flare/Halo CME associated shocks at the Earth: comparison of the predictions of three numerical models with these observations". Annales Geophysicae 20, n. 7 (31 luglio 2002): 917–35. http://dx.doi.org/10.5194/angeo-20-917-2002.
Testo completoAbstract (sommario):
Abstract. The arrival times at L1 of eleven travelling shocks associated both with X-ray flaring and with halo CMEs recorded aboard SOHO/LASCO have been considered. Close to the Sun the velocities of these events were estimated using either Type II radio records or CME speeds. Close to the Earth the shocks were detected in the data of various solar wind plasma, interplanetary magnetic field (IMF) and energetic particle experiments aboard SOHO, ACE, WIND, INTERBALL-1 and IMP-8. The real-time shock arrival predictions of three numerical models, namely the Shock Time of Arrival Model (STOA), the Interplanetary Shock Propagation Model (ISPM) and the Hakamada-Akasofu-Fry Solar Wind Model (HAFv.2) were tested against these observations. This is the first time that energetic protons (tens of keV to a few MeV) have been used to complement plasma and IMF data in validating shock propagation models. The models were all generally successful in predicting shock arrivals. STOA provided the smallest values of the "predicted minus measured" arrival times and displayed a typical predictive precision better than about 8 h. The ratio of the calculated standard deviation of the transit times to Earth to the standard deviation of the measurements was estimated for each model (treating interacting events as composite shocks) and these ratios turned out to be 0.60, 1.15 and 1.02 for STOA, ISPM and HAFv.2, respectively. If an event in the sample for which the shock velocity was not well known is omitted from consideration, these ratios become 0.36, 0.76 and 0.81, respectively. Larger statistical samples should now be tested. The ratio of the in situ shock velocity and the "Sun to L1" transit velocity (Vsh /Vtr) was in the range of 0.7–0.9 for individual, non-interacting, shock events. HAFv.2 uniquely provided information on those changes in the COBpoint (the moving Connection point on the shock along the IMF to the OBserver) which directly influenced energetic particle rise times. This model also illustrated the non-uniform upstream conditions through which the various shocks propagated; furthermore it simulated shock deformation on a scale of fractions of an AU. On the spatial scale (300 RE ), where near-Earth spacecraft are located, the passing shocks, in conformity with the models, were found to be locally planar. The shocks also showed tilting relative to the Sun-Earth line, probably reflecting the inherent directionality associated with their solar origin. Key words. Interplanetary physics (energetic particles; interplanetary shocks; solar wind plasma)
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Caraiani, Petre. "Monetary Policy Shocks and Input–Output Characteristics of Production Networks". Journal of Risk and Financial Management 16, n. 3 (2 marzo 2023): 168. http://dx.doi.org/10.3390/jrfm16030168.
Testo completoAbstract (sommario):
This paper revisits the production network’s role in transmitting monetary policy shocks. The study uses macroeconomic data for multiple OECD economies, for which it estimates the time-varying impulse response functions of GDP to monetary shocks. In contrast to recent macroeconomics papers focusing on upstreamness or downstreamness, the paper studies measures from the input–output literature, like average propagation length or fields of influence. When looking at the relationship between the production network measures and the impact of monetary policy shocks on GDP, measures like average propagation length or rows’ fields of influence, amplify the negative impact of the monetary policy shocks, while the forward linkage dampens them.
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Nabert, Christian, e Karl-Heinz Glassmeier. "The influence of resistivity gradients on shock conditions for a Petschek reconnection geometry". Annales Geophysicae 34, n. 4 (13 aprile 2016): 421–25. http://dx.doi.org/10.5194/angeo-34-421-2016.
Testo completoAbstract (sommario):
Abstract. Shock waves can strongly influence magnetic reconnection as seen by the slow shocks attached to the diffusion region in Petschek reconnection. We derive necessary conditions for such shocks in a nonuniform resistive magnetohydrodynamic plasma and discuss them with respect to the slow shocks in Petschek reconnection. Expressions for the spatial variation of the velocity and the magnetic field are derived by rearranging terms of the resistive magnetohydrodynamic equations without solving them. These expressions contain removable singularities if the flow velocity of the plasma equals a certain characteristic velocity depending on the other flow quantities. Such a singularity can be related to the strong spatial variations across a shock. In contrast to the analysis of Rankine–Hugoniot relations, the investigation of these singularities allows us to take the finite resistivity into account. Starting from considering perpendicular shocks in a simplified one-dimensional geometry to introduce the approach, shock conditions for a more general two-dimensional situation are derived. Then the latter relations are limited to an incompressible plasma to consider the subcritical slow shocks of Petschek reconnection. A gradient of the resistivity significantly modifies the characteristic velocity of wave propagation. The corresponding relations show that a gradient of the resistivity can lower the characteristic Alfvén velocity to an effective Alfvén velocity. This can strongly impact the conditions for shocks in a Petschek reconnection geometry.
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Andersen, Torben M., e Svend Hylleberg. "WAGE ADJUSTMENT AND EMPLOYMENT PERSISTENCY". Macroeconomic Dynamics 2, n. 4 (dicembre 1998): 472–91. http://dx.doi.org/10.1017/s1365100598009043.
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Persistent high unemployment has fostered the employment persistency hypothesis according to which employment changes are driven by unanticipated shocks whereas anticipated shocks that potentially could change employment are absorbed by wage changes. Empirical tests of the persistency hypothesis fail to distinguish between the properties of shocks and endogenous propagation mechanism causing persistency. This paper develops a new test strategy by explicitly distinguishing between these two factors. The methodology is applied to the manufacturing sector in Denmark, and some support in favor of an endogenous propagation mechanism causing employment persistency is found.
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Baqaee, David, e Elisa Rubbo. "Micro Propagation and Macro Aggregation". Annual Review of Economics 15, n. 1 (13 settembre 2023): 91–123. http://dx.doi.org/10.1146/annurev-economics-082322-012833.
Testo completoAbstract (sommario):
This article reviews a framework for studying the aggregation and propagation of microeconomic shocks in general equilibrium. We discuss the determinants of aggregate measures of real economic activity, like real GDP, real domestic absorption, and aggregate productivity in both efficient and inefficient environments. We also discuss how shocks from one set of producers are transmitted to other producers through prices and quantities. The framework we provide is amenable to generalization and can be used to study any collection of producers ranging from one isolated producer to an industry consisting of heterogeneous producers to an entire economy. We conclude with a brief survey of some of the applied questions that can be addressed using the analytical tools presented in this review and avenues for future work.
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Lee, Sin Yee, Zulkefly Abdul Karim, Norlin Khalid e Mohd Azlan Shah Zaidi. "The Spillover Effects of Chinese Shocks on the Belt and Road Initiative Economies: New Evidence Using Panel Vector Autoregression". Mathematics 10, n. 14 (11 luglio 2022): 2414. http://dx.doi.org/10.3390/math10142414.
Testo completoAbstract (sommario):
This paper investigates the spillover effects of Chinese real and monetary sector shocks on the Belt Road Initiative (BRI) economies. The study adopted a panel vector autoregression (PVAR) estimation technique to analyse the dynamic propagation of Chinese shocks in the real sector (gross domestic product (GDP) and trade openness (OPEN)) and monetary sector (nominal interest rate (NIR)) for a sample of 50 BRI countries from 2000 to 2017. The main results revealed that Chinese income shocks positively spill over to all macroeconomic variables except BRI countries’ consumer price index (CPI). However, the Chinese trade openness shock only has a temporary positive spillover to BRI international trade and a temporary negative spillover on its monetary policy. In addition, the Chinese monetary policy shock has a negative spillover on GDP and a positive spillover on CPI in BRI economies. Chinese shocks, however, do not constitute a significant source of variation in any interest variable. As explained by the Chinese income shock, the BRI interest rate is the highest percentage of variable variation accumulated over time. Further, the highest variation of Chinese trade shock is BRI trade openness, and lastly, the highest variation of Chinese interest rate shock is CPI in BRI economies. The beggar-thy-neighbour effect may dominate the positive trade effect and is a negative impact of the Chinese shocks. Hence, BRI economies should alleviate the adverse shocks since the upcoming rapid growth from the Chinese has disturbed the BRI economies. Our results reveal the importance of Chinese development on BRI partners’ economies and the significance of Chinese shocks in real and monetary sectors in assisting policymakers in designing international and monetary policy for BRI economies.
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Mohd Basri, Nurliyana, Zulkefly Abdul Karim e Noorasiah Sulaiman. "The Effects of Factors of Production Shocks on Labor Productivity: New Evidence Using Panel VAR Analysis". Sustainability 12, n. 20 (20 ottobre 2020): 8710. http://dx.doi.org/10.3390/su12208710.
Testo completoAbstract (sommario):
Labor productivity has an essential role in creating a more sustainable labor market platform, leading to better economic sustainability. However, the sluggish growth in labor productivity in Malaysia could hinder the vision in realizing the status of a high-income nation in the future. Thus, understanding how production shocks affect labor productivity sustainability is crucial for firms in managing their inputs (resources). This paper aims to elucidate how shocks in wage, capital intensity, and human capital may affect the dynamic of labor productivity in the Malaysian manufacturing industry. The study further explains the magnitude of this impact on labor productivity. This study employs the panel vector autoregression (PVAR) model in analyzing the propagation of the shocks through the impulse response function and variance decomposition. The main findings reveal that shocks in production factors have a positive and significant transitional impact on productivity and the cumulative effects are positive over time. The economic impact of wage shock is material, whereas capital intensity shock is moderate and only exerts a minor effect on labor productivity emanating from human capital shock. These findings provide further insights into assisting policymakers in amplifying the current labor market policy for sustainable economic growth.
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Andersen, Torben M. "Real and Nominal Propagation of Nominal Shocks". Economic Journal 114, n. 492 (5 dicembre 2003): 174–95. http://dx.doi.org/10.1046/j.0013-0133.2003.00182.x.
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Andersen, Torben M., e Niels C. Beier. "Propagation of Nominal Shocks in Open Economies". Manchester School 71, n. 6 (dicembre 2003): 567–92. http://dx.doi.org/10.1046/j.1467-9957.2003.00367.x.
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Zappalà, Guglielmo. "Sectoral Impact and Propagation of Weather Shocks". IMF Working Papers 2023, n. 053 (marzo 2023): 1. http://dx.doi.org/10.5089/9798400236518.001.
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Dewachter, Hans, Romain Houssa e Priscilla Toffano. "Spatial propagation of macroeconomic shocks in Europe". Review of World Economics 148, n. 2 (10 febbraio 2012): 377–402. http://dx.doi.org/10.1007/s10290-012-0118-1.
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Inoue, Hiroyasu. "Propagation of International Supply-Chain Disruptions between Firms in a Country". Journal of Risk and Financial Management 14, n. 10 (1 ottobre 2021): 461. http://dx.doi.org/10.3390/jrfm14100461.
Testo completoAbstract (sommario):
This study shows how import and export shocks propagate through domestic supply chains using actual Japanese supply-chain data and a world input-output table (WIOT) based on firm-level agent-based simulations. We propose three different models with which to connect the domestic firms to a WIOT. Then, we estimate the value-added losses of Japanese firms caused by shocks of different magnitudes and durations originating in China, in the EU and the US, and globally. The volume and rates at which losses increase are very different across the connection models, which indicates that the assignment of international connections to firms matters greatly. The losses increase sublinearly as the duration expands, which indicates that the shock propagation ultimately saturates the economy. Rates of saturation differ substantially depending on the assignment of international connections. The losses increase superlinearly as the initial reduction rate increases. This occurs because there is a greater probability of one supplier being replaced by other suppliers if the reduction is smaller.
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Miyamoto, Wataru, Thuy Lan Nguyen e Dmitriy Sergeyev. "How Oil Shocks Propagate: Evidence on the Monetary Policy Channel". Federal Reserve Bank of San Francisco, Working Paper Series 2024, n. 07 (10 dicembre 2023): 01–85. http://dx.doi.org/10.24148/wp2024-07.
Testo completoAbstract (sommario):
Using high-frequency responses of oil futures prices to prominent oil market news, we estimate the effects of oil supply news shocks when systematic monetary policy is switched off by the zero lower bound (ZLB) and when it is not (normal periods) in Japan, the United Kingdom, and the United States. We find that negative oil supply news shocks are less contractionary (and even expansionary) at the ZLB compared to normal periods. Inflation expectations increase during both periods, while the short nominal interest rates remain constant at the ZLB, pointing to the importance of monetary policy for oil shock propagation.
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Lario, D., I. G. Richardson, L. B. Wilson III, L. Berger, L. K. Jian e D. Trotta. "The Extended Field-aligned Suprathermal Proton Beam and Long-lasting Trapped Energetic Particle Population Observed Upstream of a Transient Interplanetary Shock". Astrophysical Journal 925, n. 2 (1 febbraio 2022): 198. http://dx.doi.org/10.3847/1538-4357/ac3c47.
Testo completoAbstract (sommario):
Abstract The properties of the suprathermal particle distributions observed upstream of interplanetary shocks depend not only on the properties of the shocks but also on the transport conditions encountered by the particles as they propagate away from the shocks. The confinement of particles in close proximity to the shocks, as well as particle scattering processes during propagation to the spacecraft, lead to the common observation of upstream diffuse particle distributions. We present observations of a rare extended anisotropic low-energy (≲30 keV) proton beam together with a trapped ≳500 keV proton population observed in association with the arrival of an oblique interplanetary shock at the Advanced Composition Explorer, the Interplanetary Monitoring Platform-8, and the Wind spacecraft on 2001 January 31. Continuous injection of particles by the traveling shock into a smooth radial magnetic field region formed in the tail of a modest high-speed solar wind stream produced an extended foreshock region of energetic particles. The absence of enhanced magnetic field fluctuations upstream of the shock results in the observation of a prolonged anisotropic field-aligned beam of ≲30 keV protons as well as a population of higher-energy (≳500 keV) protons with small pitch-angle cosine (μ ∼ 0) extending far from the shock.
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Raghavan, Mala, e Evelyn S. Devadason. "How Resilient Is ASEAN-5 to Trade Shocks? A Comparison of Regional and Global Shocks". Global Journal of Emerging Market Economies 12, n. 1 (gennaio 2020): 93–115. http://dx.doi.org/10.1177/0974910120906239.
Testo completoAbstract (sommario):
This article studies the resilience of the ASEAN region to external shocks amid the unfolding effects of the USA–China trade war. It investigates and compares the effects of regional (ASEAN) and global (USA, China) shocks on ASEAN-5 using a Structural VAR (SVAR) framework. To identify the propagation of economic shocks and spillovers on ASEAN-5, the changing trade links between the economies considered are used to account for time variations spanning the period 1978Q1–2018Q2. Three major results follow from the analyses on trade links and output multiplier effects. First, the response of ASEAN-5 to shocks from the USA and China were more pronounced than regional shocks for the period after the Asian financial crisis. Second, the increasing cumulative impact of China’s shock on ASEAN was congruous to the growing trade links and trade intensities between ASEAN and China. Third, the USA and China were dominant growth drivers for the weaker trade-linked ASEAN partners. Taken together, the results suggest that global shocks matter for the region, and the economic resilience of the region to global shocks depends on indirect effects apart from the direct trade links.
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Baley, Isaac, e Andrés Blanco. "Firm Uncertainty Cycles and the Propagation of Nominal Shocks". American Economic Journal: Macroeconomics 11, n. 1 (1 gennaio 2019): 276–337. http://dx.doi.org/10.1257/mac.20170402.
Testo completoAbstract (sommario):
We develop a framework to study the impact of idiosyncratic uncertainty on aggregate economic outcomes. Agents learn about individual characteristics, which receive infrequent, large, and persistent shocks. In this environment, idiosyncratic uncertainty moves in cycles, fluctuating between periods of high and low uncertainty; with additional fixed adjustment costs, the frequency and size of agents' actions also fluctuate in cycles. We apply our framework to study pricing behavior and the propagation of nominal shocks. We show, analytically and quantitatively, that idiosyncratic uncertainty cycles amplify the real effects of nominal shocks by generating cross-sectional dispersion in firms' adjustment frequency and in learning speed. (JEL D21, D81, D83, E31, E32, E52)
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Carvalho, Vasco M., e Alireza Tahbaz-Salehi. "Production Networks: A Primer". Annual Review of Economics 11, n. 1 (2 agosto 2019): 635–63. http://dx.doi.org/10.1146/annurev-economics-080218-030212.
Testo completoAbstract (sommario):
This article reviews the literature on production networks in macroeconomics. It presents the theoretical foundations for the role of input–output linkages as a shock propagation channel and as a mechanism for transforming microeconomic shocks into macroeconomic fluctuations. The article also provides a brief guide to the growing literature that explores these themes empirically and quantitatively.
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Stan, Claudiu Andrei, Koji Motomura, Gabriel Blaj, Yoshiaki Kumagai, Yiwen Li, Daehyun You, Taishi Ono et al. "The Magnitude and Waveform of Shock Waves Induced by X-ray Lasers in Water". Applied Sciences 10, n. 4 (22 febbraio 2020): 1497. http://dx.doi.org/10.3390/app10041497.
Testo completoAbstract (sommario):
The high energy densities deposited in materials by focused X-ray laser pulses generate shock waves which travel away from the irradiated region, and can generate complex wave patterns or induce phase changes. We determined the time-pressure histories of shocks induced by X-ray laser pulses in liquid water microdrops, by measuring the surface velocity of the microdrops from images recorded during the reflection of the shock at the surface. Measurements were made with ~30 µm diameter droplets using 10 keV X-rays, for X-ray pulse energies that deposited linear energy densities from 3.5 to 120 mJ/m; measurements were also made with ~60 µm diameter drops for a narrower energy range. At a distance of 15 µm from the X-ray beam, the peak shock pressures ranged from 44 to 472 MPa, and the corresponding time-pressure histories of the shocks had a fast quasi-exponential decay with positive pressure durations estimated to range from 2 to 5 ns. Knowledge of the amplitude and waveform of the shock waves enables accurate modeling of shock propagation and experiment designs that either maximize or minimize the effect of shocks.
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Gonzalez-Esparza, A., e E. Aguilar-Rodriguez. "Speed evolution of fast CME/shocks with SOHO/LASCO, WIND/WAVES, IPS and in-situ WIND data: analysis of kilometric type-II emissions". Annales Geophysicae 27, n. 10 (21 ottobre 2009): 3957–66. http://dx.doi.org/10.5194/angeo-27-3957-2009.
Testo completoAbstract (sommario):
Abstract. Fast CME/shocks propagating in the interplanetary medium can generate kilometric Type II (km-TII) radio emissions at the local plasma frequency and/or its harmonic, so these radio emissions provide a means of remotely tracking CME/shocks. We apply a new analysis technique, using the frequency drift of km-TII spectrum obtained by the Thermal Noise Receiver (TNR) of the WIND/WAVES experiment, to infer, at some adequate intervals, the propagation speed of six CME/shocks. We combine these results with previously reported speeds from coronagraph white light and interplanetary scintillation observations, and in-situ measurements, to study the temporal speed evolution of the six events. The speed values obtained by the km-TII analysis are in a reasonable agreement with the speed measurements obtained by other techniques at different heliocentric distance ranges. The combination of all the speed measurements show a gradual deceleration of the CME/shocks as they propagate to 1 AU. This new technique can be useful in studying the evolution of fast CME/shocks when adequate intervals of km-TII emissions are available.
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Surana, Karam S., Jacob K. Kendall e Celso H. Carranga. "Formation, Propagation and Reflection of 1D Normal Shocks in Riemann Shock Tube". Applied Mathematics 13, n. 03 (2022): 295–323. http://dx.doi.org/10.4236/am.2022.133022.
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Barrot, Jean-Noël, e Julien Sauvagnat. "Input Specificity and the Propagation of Idiosyncratic Shocks in Production Networks *". Quarterly Journal of Economics 131, n. 3 (3 maggio 2016): 1543–92. http://dx.doi.org/10.1093/qje/qjw018.
Testo completoAbstract (sommario):
Abstract This article examines whether firm-level idiosyncratic shocks propagate in production networks. We identify idiosyncratic shocks with the occurrence of natural disasters. We find that affected suppliers impose substantial output losses on their customers, especially when they produce specific inputs. These output losses translate into significant market value losses, and they spill over to other suppliers. Our point estimates are economically large, suggesting that input specificity is an important determinant of the propagation of idiosyncratic shocks in the economy.