Horizontal Propagation Research Articles

Experimental investigation of pressure fluctuation propagation in two orthogonal directions using a clapboard-type internally circulating fluidized bed

In this work, the pressure wave propagation in the vertical and horizontal directions has been studied using a self-designed clapboard-type internally circulating fluidized bed. The effects of flow regimes and solid mixture on the pressure wave propagation characteristics were analyzed in terms of time-averaged pressure, standard deviation, power spectral density, dominant frequency, propagation time delay, and attenuation. The superficial velocity ratio had a remarkable effect on the pressure wave propagation time delay in the vertical direction but had less influence on the pressure wave propagation in the horizontal direction. The particle circulation provided an extra resistance force to the horizontal pressure wave propagation and resulted in an increase in the pressure wave decay factor in the horizontal direction. The addition of glass beads and salt greatly increased the time delay and decay factor both in vertical and horizontal directions. The addition of 15% corn powder (Geldart-C group) reduced the propagation time delay but increased the decay factor.

Propagation of gravity waves and its effects on pseudomomentum flux in a sudden stratospheric warming event

Abstract. Effects of realistic propagation of gravity waves (GWs) on distribution of GW pseudomomentum fluxes are explored using a global ray-tracing model for the 2009 sudden stratospheric warming (SSW) event. Four-dimensional (4D; x–z and t) and two-dimensional (2D; z and t) results are compared for various parameterized pseudomomentum fluxes. In ray-tracing equations, refraction due to horizontal wind shear and curvature effects are found important and comparable to one another in magnitude. In the 4D, westward pseudomomentum fluxes are enhanced in the upper troposphere and northern stratosphere due to refraction and curvature effects around fluctuating jet flows. In the northern polar upper mesosphere and lower thermosphere, eastward pseudomomentum fluxes are increased in the 4D. GWs are found to propagate more to the upper atmosphere in the 4D, since horizontal propagation and change in wave numbers due to refraction and curvature effects can make it more possible that GWs elude critical level filtering and saturation in the lower atmosphere. GW focusing effects occur around jet cores, and ray-tube effects appear where the polar stratospheric jets vary substantially in space and time. Enhancement of the structure of zonal wave number 2 in pseudomomentum fluxes in the middle stratosphere begins from the early stage of the SSW evolution. An increase in pseudomomentum fluxes in the upper atmosphere is present even after the onset in the 4D. Significantly enhanced pseudomomentum fluxes, when the polar vortex is disturbed, are related to GWs with small intrinsic group velocity (wave capture), and they would change nonlocally nearby large-scale vortex structures without substantially changing local mean flows.

Three‐Dimensional Radiative Effects By Shallow Cumulus Clouds on Dynamic Heterogeneities Over a Vegetated Surface

AbstractOne‐dimensional radiative transfer solvers are computationally much more efficient than full three‐dimensional radiative transfer solvers but do not account for the horizontal propagation of radiation and thus produce unrealistic surface irradiance fields in models that resolve clouds. Here, we study the impact of using a 3‐D radiative transfer solver on the direct and diffuse solar irradiance beneath clouds and the subsequent effect on the surface fluxes. We couple a relatively fast 3‐D radiative transfer approximation (TenStream solver) to the Dutch Atmosphere Large‐Eddy Simulation (DALES) model and perform simulations of a convective boundary layer over grassland with either 1‐D or 3‐D radiative transfer. Based on a single case study, simulations with 3‐D radiative transfer develop larger and thicker clouds, which we attribute mainly to the displaced clouds shadows. With increasing cloud thickness, the surface fluxes decrease in cloud shadows with both radiation schemes but increase beneath clouds with 3‐D radiative transfer. We find that with 3‐D radiative transfer, the horizontal length scales dominating the spatial variability of the surface fluxes are over twice as large as with 1‐D radiative transfer. The liquid water path and vertical wind velocity in the boundary layer are also dominated by larger length scales, suggesting that 3‐D radiative transfer may lead to larger convective thermals. Our case study demonstrates that 3‐D radiative effects can significantly impact dynamic heterogeneities induced by cloud shading. This may change our view on the coupling between boundary‐layer clouds and the surface and should be further tested for generalizability in future studies.

Analysis of Ionospheric Disturbances Caused by the 2018 Bering Sea Meteor Explosion Based on GPS Observations.

The Bering Sea meteor explosion that occurred on 18 December 2018 provides a good opportunity to study the ionospheric disturbances caused by meteor explosions. Total electron content (TEC) is the core parameter of ionospheric analysis. TEC and its changes can be accurately estimated based on the Global Positioning System (GPS). TID is detected in time and frequency domain based on power spectrum and Butterworth filtering method. By analyzing the waveform, period, wavelength, propagation speed and space-time distribution of TID, the location of the TID source is determined, and the process of TID formation and propagation is understood. The TID caused by meteor explosions has significant anisotropy characteristic. Two types of TID were found. For the first type, the average horizontal propagation velocity is 250.22 ± 5.98 m/s, the wavelength is ~135–240 km, the average period is about 12 min, and the propagation distance is less than 1400 km. About 8 min after the meteor explosion, the first type of TID source formed and propagated radially at the velocity of 250.22 ± 5.98 m/s. For the second type, the propagation velocity is ~434.02 m/s. According to the waveform, period, wavelength and propagation velocity of the TID, it is diagnosed to be the midscale traveling ionospheric disturbances (MSTID). Based on the characteristics of TID, we infer that the TID is excited by the gravity waves generated by the meteor explosion, which is in accordance with the propagation law of gravity waves in the ionosphere. And it is estimated that the average velocity of the up-going gravity waves is about 464.58 m/s. A simple model was established to explain the formation and the propagation of this TID, and to verify the characteristics of the TID propagation caused by nuclear explosion, earthquake, tsunami, and Chelyabinsk meteorite blast. It is estimated that the position of the TID source is consistent with the meteor explosion point, which further indicates that the TID is caused by the meteor explosion and propagates radially.

Species Transferability of Klebsiella pneumoniae Carbapenemase-2 Isolated from a High-Risk Clone of Escherichia coli ST410.

Sequence type 410 (ST410) of Escherichia coli is an extraintestinal pathogen associated with multi drug resistance. In this study, we aimed to investigate the horizontal propagation pathway of a highrisk clone of E. coli ST410 that produces Klebsiella pneumoniae carbapenemase (KPC). blaKPCencoding E. coli and K. pneumoniae isolates were evaluated, and complete sequencing and comparative analysis of blaKPC-encoding plasmids from E. coli and K. pneumoniae, antimicrobial susceptibility tests, polymerase chain reaction, multilocus sequence typing, and conjugal transfer of plasmids were performed. Whole-genome sequencing was performed for plasmids mediating KPC-2 production in E. coli and K. pneumoniae clinical isolates. Strains E. coli CPEc171209 and K. pneumoniae CPKp171210 were identified as ST410 and ST307, respectively. CPEc171209 harbored five plasmids belonging to serotype O8:H21, which is in the antimicrobial-resistant clade C4/H24. The CPKp171210 isolate harbored three plasmids. Both strains harbored various additional antimicrobial resistance genes. The IncX3 plasmid pECBHS_9_5 harbored blaKPC-2 within a truncated Tn4401a transposon, which also contains blaSHV-182 with duplicated conjugative elements. This plasmid displayed 100% identity with the IncX3 plasmid pKPBHS_10_3 from the K. pneumoniae CPKp171210 ST307 strain. The genes responsible for the conjugal transfer of the IncX3 plasmid included tra/trb clusters and pil genes coding the type IV pilus. ST410 can be transmitted between patients, posing an elevated risk in clinical settings. The emergence of a KPC-producing E. coli strain (ST410) is concerning because the blaKPC-2-bearing plasmids may carry treatment resistance across species barriers. Transgenic translocation occurs among carbapenem-resistant bacteria, which may spread rapidly via horizontal migration.

Practical concept of traveltime inversion of simulated P-wave vertical seismic profile data in weak to moderate arbitrary anisotropy

We have developed a practical concept of compressional wave (P-wave) traveltime inversion in weakly to moderately anisotropic media of arbitrary symmetry and orientation. The concept provides sufficient freedom to explain and reproduce observed anisotropic seismic signatures to a high degree of accuracy. The key to this concept is the proposed P-wave anisotropy parameterization (A-parameters) that, together with the use of the weak-anisotropy approximation, leads to a significantly simplified theory. Here, as an example, we use a simple and transparent formula relating P-wave traveltimes to 15 P-wave A-parameters describing anisotropy of arbitrary symmetry. The formula is used in the inversion scheme, which does not require any a priori information about anisotropy symmetry and its orientation, and it is applicable to weak and moderate anisotropy. As the first step, we test applicability of the proposed scheme on a blind inversion of synthetic P-wave traveltimes generated in vertical seismic profile experiments in homogeneous models. Three models of varying anisotropy are used: tilted orthorhombic and triclinic models of moderate anisotropy (approximately 10%) and an orthorhombic model of strong anisotropy (>25%) with a horizontal plane of symmetry. In all cases, the inversion yields the complete set of 15 P-wave A-parameters, which make reconstruction of corresponding phase-velocity surfaces possible with high accuracy. The inversion scheme is robust with respect to noise and the source distribution pattern. Its quality depends on the angular illumination of the medium; we determine how the absence of nearly horizontal propagation directions affects inversion accuracy. The results of the inversion are applicable, for example, in migration or as a starting model for inversion methods, such as full-waveform inversion, if a model refinement is desired. A similar procedure could be designed for the inversion of S-wave traveltimes in anisotropic media of arbitrary symmetry.

A small scale laboratory test and mass-point modeling on accumulation and horizontal propagation of cohesionless granular avalanche

A small scale laboratory test and mass-point modeling on accumulation and horizontal propagation of cohesionless granular avalanche

Biomimetic partition structure infused by nano-compositing liquid to form bio-inspired self-healing surface for corrosion inhibition

Finding versatile coating to prohibit three-dimensional corrosion propagation on metal surface is of essential importance. In this report, inspired by the natural pomegranate fruit, we have fabricated the partition structure by electrochemical method. The as-built Ce(OH)3 nanowall structure has circumvented the partition structure to inhibit the horizontal corrosion propagation on metal surface. Moreover, the partition structure is modified to realize superhydrophobicity and superoleophilicity wettability. Endowed by the two properties, binary-phase fluid is used to infuse the as-modified partition structure to form nano-compositing liquid infused surface (NCLIS). In vertical direction, the upgraded Nepenthes pitcher plant inspired surface has afforded much higher corrosion inhibition effect to the underneath metal substrate. After immersion for 600 h, Z0.01Hz of NCLIS is still as high as 1.19 × 108 Ω·cm2, which is ca. 2 orders of the magnitude larger than CS covered by liquid infused surface (LIS CS) with the same immersion period in seawater. Moreover, NCLIS coating shows self-healing capability to the underlying metal in atmospheric and seawater environment, even enduring the external mechanical damage. Therefore, the dual biomimetics of pomegranate and Nepenthes pitcher plant has afforded a versatile strategy to inhibit the corrosion from the horizontal and vertical directions.

Oscillatory Convection Onset in a Porous Rectangle with Non-analytical Corners

The analytical theory on Darcy–Bénard convection is dominated by normal-mode approaches, which essentially reduce the spatial order from four to two. This paper goes beyond the normal-mode paradigm of convection onset in a porous rectangle. A handpicked case where all four corners of the rectangle are non-analytical is therefore investigated. The marginal state is oscillatory with one-way horizontal wave propagation. The time-periodic convection pattern has no spatial periodicity and requires heavy numerical computation by the finite element method. The critical Rayleigh number at convection onset is computed, with its associated frequency of oscillation. Snapshots of the 2D eigenfunctions for the flow field and temperature field are plotted. Detailed local gradient analyses near two corners indicate that they hide logarithmic singularities, where the displayed eigenfunctions may represent outer solutions in matched asymptotic expansions. The results are validated with respect to the asymptotic limit of Nield (Water Resour Res 11:553–560, 1968).

Experimental evaluation of punching shear capacity of reinforced concrete slabs with horizontal crack due to compression rebar corrosion

AbstractPunching shear capacity of deteriorated reinforced concrete slab is experimentally investigated in this study. Since horizontal crack near the upper side rebar is often observed in deteriorated reinforced concrete bridge deck slabs due to rebar corrosion, horizontal crack propagation behavior was investigated by accelerated electric corrosion test. Then, in order to evaluate the influence of the horizontal crack on punching shear capacity of slabs, loading tests were carried out using the test specimens with the corrosion‐induced crack and with an artificial horizontal crack. According to the test results, the horizontal crack near the upper side rebar has a significant impact on punching shear capacity of slabs, and it is confirmed that punching shear capacity of reinforced concrete slab correlates to the width of the horizontal crack. Also, it is revealed that cover concrete above horizontal crack does not effectively work if width of the horizontal crack grows to a certain amount.

On the spreading of non-canonical thermals from direct numerical simulations

We present results from direct numerical simulations on laminar and turbulent non-canonical thermals with an initial rectangular density distribution at a Reynolds number of Re = 500 and Re = 5000, respectively. We find the non-canonical shape to induce strong azimuthal variations in the thermal for both the laminar and turbulent cases. These include noticeable differences in downward and horizontal propagation speeds as well as differences in the strength of the vortex tube. These differences persist over a significant period of time and help generate a cross-flow component that is otherwise not present in canonical cases. The cross-flow component is in the opposite direction to that observed in gravity currents with the same initial density distribution. This is counterintuitive seeing that both flows are solely driven by buoyancy. By extracting the three-dimensional streamlines, we find the descending vortex tube to force the dense fluid to follow a helical path.

Unraveling the complex deformation pattern at Yellowstone plateau through seismicity and fracture analysis

The intense unrest of the Yellowstone volcanic plateau is manifested through diffuse seismic activity, earthquake swarms, and episodes of complex surficial deformation that have been related to magmatic fluid transfer in the upper crust over the past several decades. While past studies have focused on modeling contemporary geophysical data, there has not been a fully-integrated evaluation of seismicity, fault kinematics, and stress field. Here we analyze a catalog of 10,201 relocated earthquakes recorded between 2010 and 2016 and determine 224 well-constrained double-couple focal mechanisms. The majority of the focal mechanisms (65%) are associated with the 2010 Madison Plateau seismic swarm. The focal mechanisms are predominantly strike-slip with subordinate normal faulting mechanisms. Possible causes of this predominance and of the concurrence of both kinematics are here discussed, in order to unravel the influence of magmatic processes such as past sill intrusions. The earthquake catalog has been analyzed in terms of location, time, and kinematics according to the phases of surficial deformation documented by GPS data in order to identify systematic patterns of deformation and has been compared to the 1988–2009 seismicity. The continuous downwarping of the overburden from 2010 to 2016 was accomodated by structural adjustment of the shallow crust through strike-slip motions on a multitude of scattered small fault planes. Furthermore, the predominance of strike-slip faulting during seismic swarms occurs when the fluid overpressure induces horizontal propagation of vertical fractures with strike-slip motions, followed by horizontal fluid flow.

Influence of Horizontal and Vertical Barriers on Fire Development for Ventilated Fa\xe7ades

Although using various innovative materials for ventilated facade systems positively contribute to the energy efficiency of buildings, the application of such materials can also pose a certain risk of fire propagation through the façade. In the last decade, medium and large-scale tests, as well as numerical analysis have been performed to assess the impact of fire barriers on fire propagation through ventilated façades. However, the number of fire barriers and their specific positions can also have an effect on the fire safety of facades, which has not been studied. Consequently, the question arises whether real fire exposure on a façade can be adequately simulated and analysed in sufficient detail, by using large-scale testing methods. This paper aims to conduct a parametric analysis on a broader range of large-scale samples by using the procedure given in the standard BS 8414-1:2015 + A1:2017. To understand better the impact of the number and position of cavity barriers for different types of insulation materials (stone wool/PIR/phenolic foam) used in modern façade systems with non-combustible cladding (ACM-A2). Seven tests were carried out in Croatia between October 2017 and April 2018. In the case of combustible insulation, two horizontal barriers were insufficient in preventing fire propagation. Temperatures accumulated above 600°C, reaching 840°C in PIR insulation and 979°C in phenolic foam insulation. For the same sample designed with non-combustible insulation, the maximum temperature measured was 133°C. Facades with combustible insulation passed the test only when four horizontal barriers were used. The existence of vertical barriers had a positive impact on preventing the fire propagation because the insulation on the left side of the chamber, behind the vertical barrier, remained undamaged. Vertical barriers on the right side of the chamber delayed the horizontal fire propagation from the main wall to the wing wall depending on the type of insulation. The results from these tests can serve as a basis for future research on the effects of fire barriers on fire propagation.

Numerical Simulation of Hydraulic Fracturing Effect Based on Abaqus

This study simulates the hydraulic fracturing process based on ABAQUS, and obtains the results of hydraulic fracturing fracture propagation under the influence of multi-parameters. Our research shows that:The effect of reservoir modification increases with the increase of injection rate of fracturing fluid. Under the condition of 8m3/min or above, the fracture can communicate with the fault zone 100m away from the bottom of the well. Under the condition of 10cP, the effect of fracture propagation in formation is good. Under the condition of 50cP, the effect of fracture propagation in fracture zone is good. Under the condition of 200cP, the effect of crack propagation is poor. When the injection volume of fracturing fluid is between 0 and 1440m3, the effect of fracture propagation increases gradually. When the injection volume of fracturing fluid is larger than 1440m3, the contribution of continuous injection become weak. The maximum vertical crustal stress results in the fracture extending to the depth. The maximum horizontal crustal stress results in the horizontal propagation of fractured fractures. This study analyzed the influence of formation parameters and hydraulic fracturing parameters on fracture propagation. It also plays an active role in predicting the effect of hydraulic fracturing.

Thermal shock resistance and failure analysis of plasma-sprayed thick 8YSZ-Al2O3 composite coatings

The effects of Al2O3 content and spraying power on bonding strength and thermal shock resistance of plasma-sprayed 8YSZ-Al2O3 composite coatings with thickness of ~900 μm were investigated. Thermal shock resistance decreased obviously with increasing the Al2O3 content and test temperature, while bonding strength showed an increasing trend. Relatively, the effect of spraying power on thermal shock resistance and bonding strength was small. Moreover, the Young's modulus of coating surface was increased from 99.07GPa to 134.59GPa with increasing Al2O3 content from 10 wt% to 40 wt%, while the corresponding thermal expansion coefficient (CTE) decreased from 9.68 × 10−6/°C to 7.29 × 10−6/°C. Thus, residual stresses on the surface of composite coatings changed from tensile (+13.3 MPa) to compressive (−189.0 MPa), which would cause greater stresses gradient as well as strain energy in the direction of coating thickness. During thermal shock testing, thermal stress increased sharply with increasing the test temperature and Al2O3 content. Meanwhile, introduction of Al2O3 resulted in denser microstructure, which was detrimental for stress releasing. According to the results, the horizontal crack propagation in the interface area caused by thermal stress and volume contraction caused by amorphous phase recrystallization were considered to be the main factors for thermal shock failure.

Investigating the compatibility of thermoplastic polyester elastomer/high-density polyethylene blends and its effect on the horizontal flame propagation

ABSTRACTThis paper explores the use of a terpolymer, composed of ethylene–butyl acrylate–glycidyl methacrylate (PE–BA–GMA) as a compatibiliser for blending thermoplastic polyester elastomer (Hytrel) and high-density polyethylene. We have studied the effect of adding this terpolymer on the morphology of the blends, and as a result, its effect on the mechanical properties. These properties have been further corroborated with X-Ray Diffraction Spectroscopy (XRD) and Dynamic Rheology of the blends. Fourier transform infrared spectroscopy (FTIR) has been used to study the mode of compatibilisation, while rheology has proved useful to correlate the phase morphology with SEM. We have also studied the effect of compatibilisation of this blend on Limiting Oxygen Index (LOI) and horizontal flame velocity.

Mechanical Properties and Thermal Shock Resistance of 8YSZ-Al2O3 Composite Coatings with Different Thicknesses

The mechanical properties and thermal shock resistance of plasma-sprayed 8YSZ-Al2O3 composite coatings with different thicknesses have been analyzed. At a thickness of 330 μm, the Young’s modulus of the coating surface increased from 96.54 to 121.39 GPa and the surface hardness from 6.63 to 9.14 GPa when the Al2O3 content was varied from 10 to 40 wt.%. Adding more alumina in the coating resulted in a change in the coating surface residual stress from tensile (48.8 MPa) to compressive (−115.9 MPa), while the thermal shock resistance at 1100 °C decreased from 162 to 56 cycles. Moreover, at given Al2O3 content, the thermal shock resistance of the coating decreased drastically when its thickness was increased, which can be attributed to the enhanced Young’s modulus and hardness near the bond coat/ceramic coating interface. An increase in the ceramic thickness resulted in a significant stress gradient as well as strain energy in the direction of the coating thickness, bringing about high thermal stress during thermal shock testing. The horizontal crack propagation caused by thermal stress in the interface area could be the main reason for coating failure.

Evidence of Mid- and Low-Latitude Nighttime Ionospheric $E$ –$F$ Coupling: Coordinated Observations of Sporadic $E$ Layers, $F$ -Region Field-Aligned Irregularities, and Medium-Scale Traveling Ionospheric Disturbances

We present the observational evidence of $E$ - and $F$ -region field-aligned irregularities (FAIs), nighttime medium-scale traveling ionospheric disturbances (MSTIDs), and a sporadic $E$ ( $E_{\text {S}}$ )-layer using the Wuhan very-high-frequency (VHF) coherent scatter radar, Wuhan Global Navigation Satellite System (GNSS) network, and Wuhan ionosonde. We observed simultaneously E and F FAIs by VHF radar and the $E_{\text {S}}$ -layer and spread- $F$ by Wuhan ionosonde. We also observed MSTIDs using the Wuhan GNSS network in a southwestward direction of propagation and horizontal propagation velocity of less than 180 m/s, for a period of ~33 min. Simultaneous observations of an $E_{\text {S}}$ -layer and FAIs in the $E$ -region and FAIs in the $F$ -region suggested the existence of an electrodynamic coupling between the $E$ and $F$ regions in the mid- and low-latitude nighttime ionosphere. A polarized electric field associated with nighttime MSTIDs can generate the uplift movements of the $F$ -region’s electron density. This uplift effect consequently can excite the gradient drift instability (GDI) with an accompanying enhanced vertical gradient of the $F$ -layer’s electron density. Our results indicated that the $F$ -region MSTIDs excited by Perkins instability might be further modulated by the $E \times B$ effect and subsequently can evolve to spread-F like FAIs. Our observational investigation provided the first evidence of the full dynamics and links among different ionospheric disturbances in a mid- and low-latitude nighttime region of China.

On gravity currents of fixed volume that encounter a down-slope or up-slope bottom

We consider a gravity current released from a lock into an ambient fluid of smaller density, that, from the beginning or after some horizontal propagation X1, propagates along an inclined (up- or down-) bottom. The flow (assumed in the inertial-buoyancy regime) is modeled by the shallow-water (SW) equations with a jump condition applied at the nose (front). The behavior of the current is dominated by the slope angle, θ, but is also affected by additional dimensionless parameters: the aspect ratio of the lock x0/h0, the height ratio of the ambient to lock, H/h0, and the distance of the backwall from the beginning of the slope, X1/x0. We show that the stability of the interface, reflected by the value of the bulk Richardson number, Ri, is essential in the interpretation and modeling. In the upslope flow, Ri increases and hence entrainment/mixing effects are unimportant. In the downslope flow, the current first accelerates and Ri decreases; this enhances entrainment and drag, which then decelerate the current. We show that the accelerating-decelerating downstream current is reproduced well by a SW model combined with a simple closure for the entrainment and drag. A comparison of the theoretical results with previously published experimental data for both upslope flow and downslope flow show fair agreement.

Interfacial imperfection study in pres-stressed rotating multiferroic cylindrical tube with wave vibration analytical approach

In the present paper, two distinct multiferroic composites are taken into account, i.e., PE (piezoelectric)/PM (piezomagnetic). An analytical technique is applied to study the shear horizontal (SH) wave propagation in a layered pre-stressed rotating cylindrical tube structure consisting of a PE material layer which is wrapped on PM material having an imperfect interface. It is assumed that consider interface is mechanical, electrically and magnetically damaged. Dispersion relations are obtained for electrical-magnetic open/short boundary conditions. Distinct graphs are drawn (numerically) to exhibit the influence of parameters like rotation, initial stress and imperfect parameters (mechanical, electrical and magnetic) on phase velocity. Parametric results on the phase velocities yield a significant conclusion of which some are: (a) Performance has Piezo-composites have a great impact on phase velocity. (b) The mechanical imperfection affects the more on phase velocity along with the combination of thickness ratio and wave number in respect to electrical -magneto imperfection (c) The PE/PM stiffening can monotonically increase the speed of phase.