Barrier Configurations Research Articles

Scattering of water waves by surface-piercing barriers using dual BEM

The primary purpose of this paper is using the dual boundary element method (dual BEM) to analyze the reflection and the transmission of water waves resulting from a rectangular block, a single vertical thin barrier, a system of vertical, equally spaced, thin barriers, and thin barriers of specific shape (e.g., type L, T, T1, FR, FL and type ┌┐). The present model is formulated and applied to study the effects of surface-piercing barriers, which are modeled as zero-thickness structures. Two-dimensional problems are considered, and the linear gravity wave theory is used. Furthermore, the accuracy and the validity of the present method have been verified by comparing results with: (a) numerical results obtained from published analytical solutions, (b) other numerical results and (c) reliable experimental data. A very good agreement is observed. Finally, the reflection and transmission coefficients of all the examined configurations of barriers for various wave conditions are presented and discussed. The results show that the reflection coefficient steadily increases up to unity for the single barrier as the wavenumber increases while for the double barriers reflection coefficient oscillates between 0 and 1. For specific shape, there will be no phase difference problem for type L, so the transmission coefficients of type L are smaller than those of type T and T1. The performance characteristics indicated that the surface-piercing barriers may be beneficial to the design of the marine infrastructures in the future.

Cultural, ideological and practical barriers to open access adoption within the UK Academy: an ethnographically framed examination

This article presents the results of part of an ethnographic study which examined the perceptions, development and conceptions of open access (OA) practice across the UK higher education environment. It details a qualitative semi-structured interview data capture approach with many institutionally based OA practitioners, which provided a narrative picture of academic and institutional responses to emerging OA dissemination paradigms. Through an analytical process incorporating qualitative content analysis and ideological critique, it focuses on practitioner perceptions of the types and configuration of barriers between scholars and a greater cultural adoption of OA practices. While the greatest problems perceived relate to academic intellectual disengagement or indifference to publishing praxis change, no singular cause of resistance was identified. The study reveals practitioners’ perceptions of a multiplicity of operational, technological and ideological barriers blocking progress, and consequently a picture of academic engagement remaining disappointingly patchy. Moreover, moves to increase scholarly compliance through allying it to modalities of fiscal income and metrics, while potentially enhancing practical compliance, appear to risk distorting any revolutionary configuration of OA practices.

Topology optimization of reactive acoustic mufflers using a bi-directional evolutionary optimization method

This article proposes an acoustic muffler design procedure based on finite element models and a Bi-directional Evolutionary Acoustic Topology Optimization. The main goal is to find the best configuration of barriers inside acoustic mufflers used in the automotive industry that reduces sound pressure level in the outlet of the muffler. The acoustic medium is governed by Helmholtz equation and rigid wall boundary conditions are introduced to represent acoustic barriers. The continuum problem is written in the frequency domain and it is discretized using the finite element method. The adopted objective function is Transmission Loss (TL). Increasing TL guarantees that the sound pressure level ratio between outlet and inlet of the muffler is reduced. To find the configuration of acoustic barriers that increases the Transmission Loss function of the muffler an adaptation of the Bi-directional Evolutionary Structural Optimization (BESO) method is used. Applying the proposed design procedure topologies in 2D models are reached, which raises the Transmission Loss function for one or multiple frequencies. Three examples are presented to show the efficiency of the proposed procedure.

Solar cycle variation of the venus magnetic barrier

Although there is no intrinsic magnetic field at Venus, the convected interplanetary magnetic field piles up to form an induced magnetosphere around the planetary ionosphere. Previous investigations show that the magnetic barrier, the part of the induced magnetosphere in the dayside inner magnetosheath, can act as an effective obstacle to the solar wind during solar maximum, and the magnetic barrier can stop the solar wind even during solar minimum. In this study, we perform a comprehensive statistical study of the magnetic barrier near the terminator during almost a complete solar cycle by using Venus Express magnetic data. The magnetic barrier configuration is located at the dayside even near the terminator and a hemispheric asymmetry exists during the whole solar cycle. We also demonstrate that the general magnetic barrier configuration is controlled by the interplanetary magnetic field orientation and solar cycle dependent. The magnetic barrier under IMF quasi-perpendicular to the solar wind flow is stronger than quasi-parallel to the solar wind flow during the solar cycle, and this difference becomes larger with the increase in solar activity.

Numerical simulation of the effect of wind barrier openings on high-speed wind flow around a heliostat field

• A two-dimensional numerical simulation was conducted. • We investigated the effect of varying the wind barrier opening size on wind flow. • We analyzed the vertical profile of wind velocity and turbulence kinetic energy in the domain considered. • We proposed the recommended wind barrier opening size for reduction of wind velocity and turbulence kinetic energy. The application of heliostats for solar power tower plants has increased in recent years. Most of the solar power tower plants installed are on flat terrain, and they may be subjected to wind loads. In the present study, a two-dimensional numerical simulation of turbulent high-speed wind flow around a heliostat field was analyzed and the wind barrier effect on the flow was investigated with use of the computational fluid dynamics commercial code COMSOL ( k - ε turbulence model). The calculation was performed for different configurations of wind barriers with opening sizes of 0 m, 0.2 m, 0.5 m, and 1 m, respectively, and four heliostat orientations in each case: 0°, 30°, 60°, and 90°. The results show that the use of wind barriers reduces wind velocity in a solar power tower plant. We found that wind barriers with small openings (0.2 m and 0.5 m) are effective in reducing wind speed below 10 m from the ground and create, at the same time, less turbulence kinetic energy than the other configurations (0 m and 1 m).

Ultimate capacity of barrier–deck anchorage in MTQ TL-5 barrier reinforced with headed-end, high-modulus, sand-coated GFRP bars

This paper presents an experimental program to justify the barrier design at the barrier–deck junction when compared to the factored applied transverse vehicular loading specified in the Canadian Highway Bridge Design Code (CHBDC). Compared to the dimensioning and the glass fibre reinforced polymer (GFRP) bar detailing of a recently crash-tested GFRP-reinforced barrier, the adopted barrier configurations in this paper were similar to those specified by Ministry of Transportation of Québec (MTQ) for TL-5 barrier except that the base of the barrier was 40 mm narrower and the deck slab is of 200 mm thickness, leading to reduction in the GFRP embedment depth into the deck slab. Four full-scale TL-5 barrier specimens were tested to collapse. Correlation between the experimental findings and the factored applied moments from CHBDC equivalent vehicle impact forces resulting from the finite-element modelling of the barrier–deck system was conducted followed by recommendations for use of the proposed design in highway bridges in Québec.

Andreev reflection enhancement in semiconductor-superconductor structures

We develop a theoretical approach for modeling a wide range of semiconductor-superconductor structures with arbitrary potential barriers and a spatially dependent superconducting order parameter. We demonstrate asymmetry in the conductance spectrum as a result of a Schottky barrier shape. We further show that the Andreev reflection process can be significantly enhanced through resonant tunneling with appropriate barrier configuration, which can incorporate the Schottky barrier as a contributing component of the device. Moreover, we show that resonant tunneling can be achieved in superlattice structures as well. These theoretically demonstrated effects along with our modeling approach enable much more efficient Cooper pair injection into semiconductor-superconductor structures, including superconducting optoelectronic devices.

Experimental and simulation study of the restoration of a thallium (I)-contaminated aquifer by Permeable Adsorptive Barriers (PABs)

Permeable Adsorptive Barriers (PABs), filled with a commercial activated carbon, are tested as a technique for the remediation of a thallium (I)-contaminated aquifer located in the south of Italy. Thallium adsorption capacity of the activated carbon is experimentally determined through dedicated laboratory tests, allowing to obtain the main modelling parameters to describe the adsorption phenomena within the barrier. A 2D numerical model, solved by using a finite element approach via COMSOL Multi-physics®, is used to simulate the contaminant transport within the aquifer and for the PAB design. Investigations are carried out on an innovative barrier configuration, called Discontinuous Permeable Adsorptive Barrier (PAB-D). In addition, an optimization procedure is followed to determine the optimum PAB-D parameters, and to evaluate the total costs of the intervention. A PAB-D made by an array of wells having a diameter of 1.5m and spaced at a distance of 4m from each other, is shown to be the most cost-effective of those tested, and ensures the aquifer restoration within 80years. The simulation outcomes demonstrate that the designed PAB-D is an effective tool for the remediation of the aquifer under analysis, since the contaminant concentration downstream of the barrier is below the thallium regulatory limit for groundwater, also accounting for possible desorption phenomena. Finally, the best PAB-D configuration is compared with a continuous barrier (PAB-C), resulting in a 32% saving of adsorbing material volume, and 36% of the overall costs for the PAB-D.

An AI-based workflow for estimating shale barrier configurations from SAGD production histories

An artificial intelligence (AI)-based workflow is deployed to develop and test procedures for estimating shale barrier configurations from SAGD production profiles. The data employed in this project are derived from a set of synthetic SAGD reservoir simulations based on petrophysical properties and operational constraints representative of Athabasca oil sands reservoirs. Initially, a two-dimensional reservoir simulation model is employed. The underlying model is homogeneous. Its petrophysical properties, such as the porosity, permeability, initial oil saturation and net pay thickness, have been taken from average values for several pads in Suncor’s Firebag project. Reservoir heterogeneities are simulated by superimposing sets of idealized shale barrier configurations on the homogeneous model. The location and geometry of each shale barrier is parameterized by a unique set of indices. The resulting heterogeneous model is subjected to flow simulation to simulate SAGD production. Next, a two-step workflow is followed: (1) a network model based on AI tools is constructed to match the output of the reservoir simulation (shale indices are inputs, while production rate is the output) for a known training set of shale barrier configurations; (2) for a new SAGD production history generated via reservoir simulation with a shale barrier configuration that is unknown to the AI model generated in Step 1, an optimization scheme based on a genetic algorithm approach is adopted to perturb the shale indices until the difference between the target production history and the production history predicted from the AI model is minimized. A number of cases have been tested. The results show a good agreement between the shale barrier configurations predicted by the AI model with the configurations used to generate production histories in the reservoir simulation model (i.e., the “true” model). Thus, this optimization workflow offers potential to become an alternative tool for indirect inference of the uncertain distribution of shale barriers in SAGD reservoirs from data capturing field performance. This work highlights the potential of an AI-based workflow to infer the presence and distribution of heterogeneous shale barriers from field SAGD production time series data. It presents an innovative parameterization scheme suitable for representing heterogeneous characteristics of shale barriers. If this approach proves to be successful, it could allow the distribution of shale barriers to be inferred together with the impact of these barriers on SAGD performance. This would provide a basis for developing operating strategies to reduce the impact of the barriers.

Cogging torque reduction of Interior Permanent Magnet Synchronous Motor (IPMSM)

In this paper using combination of two separated ideas the torque ripple of Interior Permanent Magnet Synchronous Motor (IPMSM) is reduced. These two ideas are rotor PM segmented and modifying the rotor structure based on pole-arc ratio of flux barrier optimization. In addition the torque ripple due to the reluctance torque component decreased too. Analysis and simulation results including saturation have been performed using analytical method and Finite Element Method (FEM). The rotor flux barrier configuration of the proposed design is carried out by Response Surface Method (RSM) as optimization technique which is verified by FEM

Effectiveness of vertical barriers in preventing lateral flame spread over exposed EPS insulation wall

Insulation panels made of organic, combustible materials are frequently used in the exterior thermal insulation systems (ETIS) for buildings. Such combustible insulation panels have been involved in several catastrophic building fires in recent years in China. One potential strategy to mitigate this fire hazard is to limit fire spread over the ETIS. The present work evaluates the effectiveness of vertical fire barriers in inhibiting fire spread over exposed insulation walls made of expanded polystyrene (EPS) panels. Reduced-scale experiments were carried out indoors using EPS panels with or without two vertical barriers made of non-combustible mineral wool, the fire started at the bottom center of the middle panel. The interval and width of the barriers were varied systematically, while the temperature distribution on the wall, the radiation heat flux from the fire, and the infra-red (IR) images were recorded. To demonstrate the validity of the concept, an outdoor, full-scale experiment was carried out using a 7-floor building. Our reduced-scale experiments showed that the installation of two vertical fire barriers successfully stopped the lateral flame spread, decreasing the peak temperatures of the two side panels by about 300°C for all barrier configurations tested. When barrier width was fixed at 5cm, an increase of the barrier interval from 30 to 90cm led to increases in the peak temperatures, radiation heat flux, and the maximum rate of upward flame spread. By contrast, when barrier interval was fixed at 90cm, an increase of the barrier width from 2 to 5cm had little influence on the combustion dynamics of the middle panel but the peak temperature on the side panels dropped, consistent with the smaller heat transferred with wider fire barriers. In the regions of the side panels next to the barriers, pyrolysis and deformation could be observed with barrier widths of 2 and 3cm, but not 5cm. Finally, our outdoor, full-scale experiment demonstrated that a 30cm wide vertical barrier made of air-filled cement successfully stopped the lateral flame spread over exposed EPS wall. The study highlights the effectiveness of vertical fire barriers in preventing the lateral flame spread over the exposed EPS insulation wall and provides another option for enhancing the fire safety of the combustible insulation systems.

Scattering of oblique surface water waves by thin vertical barrier over undulating bed topography

The present study deals with the scattering of oblique surface water waves by small undulation on the bottom in the presence of a thin vertical barrier. Here, three different configurations of vertical barriers are investigated. Perturbation analysis is employed to determine the physical quantities, namely, the reflection and transmission coefficients. In this analysis, many different Boundary Value Problems (BVPs) are obtained out of which the first two bvps are considered. The zeroth order bvp is solved with the aid of eigenfunction expansion method. The first order reflection and transmission coefficients are derived in terms of the integrals by the method of the Green’s integral theorem. The variation of these coefficients is plotted and analyzed for different physical parameters. Furthermore, the energy balance relation, an important relation in the study of water wave scattering, is derived and checked for assuring the correctness of the numerical results for the present problem.

ZPulse characteristics and pattern analysis of corona discharges with different pressboard insulation barriers

Corona discharge is one of the significant problem associated with power transformer and can occur due to sharp points or free conductive particles. The existence of sharp points at joints or terminals or conducting parts is very difficult to avoid completely during the manufacturing process of the transformer. The free conductive particles can arise from manufacturing process or can be developed during service period of the transformer. These free conductive particles can adhere to paper or pressboard insulation barrier or freely move in the bulk oil. In transformers highly non uniform fields are often present due to sharp points and free conducting particles, so detecting their effect on the transformer is very critical for the life of transformer. In the present investigation, to generate a high voltage corona in air or oil, a test chamber of dimension 50cm x 50cm x 50cm made from Perspex material and fitted with removable needle plane electrode arrangement has been used. The discharge measurements are carried out using Partial Discharge (PD) measurement technique according to IEC 60270. The results obtained are presented and discussed. Discharge pulse characteristics such as magnitude, rise time and decay time of different needle plane barrier configurations are analyzed. This paper also discussing pattern analysis and dominant frequency of discharges due to different needle plane barrier configurations.

The degradation of oxadiazon by non-thermal plasma with a dielectric barrier configuration

To explore the feasibility of a degradation approach by non-thermal plasma and the corresponding degradation pathways, studies on the oxadiazon removal in synthetic wastewater by a dielectric barrier discharge plasma reactor were investigated. The loss of the nitro group, dechlorination and ring cleavage is mainly involved in the non-thermal plasma degradation pathways of oxadiazon in a solution based on the OES and LC-MS analysis. Detection of EC25 and the production of the chlorine ion and nitrate ion further demonstrate the feasibility and validity of the approach. The conditions with a proper applied voltage, solution flow rate, oxygen flow rate, and solution pH contribute to the plasma degradation processes with a degradation ratio of over 94%.

Fermi edge singularities in transport through lateral GaAs quantum dots

We measure tunnelling currents through electrostatically defined quantum dots in a GaAs/AlGaAs heterostructure connected to two leads. For certain tunnelling barrier configurations and high sample bias we find a pronounced resonance associated with a Fermi edge singularity. This many-body scattering effect appears when the electrochemical potential of the quantum dot is aligned with the Fermi level of the lead less coupled to the dot. By changing the relative tunnelling barrier strength we are able to tune the interaction of the localised electron with the Fermi sea.

地層処分人工バリアの設定値に関する考察

地層処分人工バリアの設定値に関する考察

Corrigendum.

CorrigendumCorrigendumPublished Online:27 Jan 2017https://doi.org/10.1152/jn.z9k-4005-corr.2016Original articleMoreSectionsPDF (48 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Wong AL, Goldsmith J, Krakauer JW. A motor planning stage represents the shape of upcoming movement trajectories. J Neurophysiol 116: 296–305, 2016. First published April 20, 2016; doi: https://doi.org/10.1152/jn.01064.2015.A graphing error was discovered in Fig. 3A in which the heights of the point-to-point bars (reflecting reaction times) were incorrect. However, the point-to-point reaction time values plotted in Fig. 3B, as well as the numerical values reported in the text, are correct. As all statistics were conducted using the values reported in the text, this error does not affect the reported statistics or the conclusions of the paper.Fig. 3.Results from experiment 2. A: unlike point-to-point reaches generated in the context of curved movements (left bars), point-to-point RTs performed in isolation (right bars) were not modulated by the presence of a path cue [point-to-point with (PPlan) or without (PNoPlan) a path cue]. This finding is different from that noted in experiment 1, where an RT cost was observed for point-to-point movements. B: Hick's law curves for the Planning (blue) and No-Planning (green) conditions for different numbers of barrier configurations. Curve fits excluded the point-to-point movements performed in isolation (filled triangles). RTs of point-to-point movements generated in the context of curved reaches have been extracted for comparison (open triangles).Download figureDownload PowerPointThis article has no references to display. Download PDF Previous Back to Top FiguresReferencesRelatedInformation Related ArticlesA motor planning stage represents the shape of upcoming movement trajectories 01 Aug 2016Journal of Neurophysiology More from this issue > Volume 117Issue 1January 2017Pages 476-476 Copyright & PermissionsCopyright © 2017 the American Physiological Societyhttps://doi.org/10.1152/jn.z9k-4005-corr.2016PubMed28130389History Published online 27 January 2017 Published in print 1 January 2017 Metrics

地層処分人工バリアの設定値に関する考察

地層処分人工バリアの設定値に関する考察

地層処分人工バリアの設定値に関する考察

地層処分人工バリアの設定値に関する考察

Reply to the 'Comment on "Proton transport in barium stannate: classical, semi-classical and quantum regime"'.

We respond to the erroneous criticisms about our modeling of proton transport in barium stannate [G. Geneste et al., Phys. Chem. Chem. Phys., 2015, 17, 19104]. In this previous work, we described, on the basis of density-functional calculations, proton transport in the classical and semi-classical regimes, and provided arguments in favor of an adiabatic picture for proton transfer at low temperature. We re-explain here our article (with more detail and precision), the content of which has been distorted in the Comment, and reiterate our arguments in this reply. We refute all criticisms. They are completely wrong in the context of our article. Even though a few of them are based on considerations probably true in some metals, they make no sense here since they do not correspond to the content of our work. It has not been understood in the Comment that two competitive configurations, associated with radically different transfer mechanisms, have been studied in our work. It has also not been understood in the Comment that the adiabatic regime described for transfer occurs in the protonic ground state, in a very-low barrier configuration with the protonic ground state energy larger than the barrier. Serious confusion has been made in the Comment with the case of H in metals like Nb or Ta, leading to the introduction of the notion of (protonic) "excited-state proton transfer", relevant for H in some metals, but (i) that does not correspond to the (ground state) adiabatic transfers here described, and (ii) that does not correspond to what is commonly described as the "adiabatic limit for proton transfer" in the scientific literature. We emphasize, accordingly, the large differences between proton transfer in the present oxide and hydrogen jumps in metals like Nb or Ta, and the similarities between proton transfer in the present oxide and in acid-base solutions. We finally describe a scenario for proton transfer in the present oxide regardless of the temperature regime.