Experimental confirmation of superposition from small-scale explosions

1988 ◽  
Vol 78 (3) ◽  
pp. 1059-1073 ◽  
Author(s):  
Brian W. Stump ◽  
Robert E. Reinke
Keyword(s):  
Propagation Path ◽  
Corner Frequency ◽  
Experimental Program ◽  
Small Scale ◽  
Linear Superposition ◽  
Source Effects ◽  
Single Burst ◽  
Constant Delay Time ◽  
Plane Passing ◽  
Burst Data

Abstract An in situ experimental program in alluvium is implemented and analyzed to test linear superposition. After separating stochastic and deterministic propagation path effects, direct superposition is experimentally validated at 20 m for two 5-lb charges spaced as close as 2 m in alluvium. The charges are separated by the scaled range of 147 m/kt1/3 and observed at the scaled range of 1470 m/kt1/3. Finite-spatial source effects are observed and simulated in the plane passing through two charges separated by 2 to 10 m. The deterministic single-burst waveforms are used to model the multiple-burst data. The effects observed and simulated include direct superposition below the corner frequency, shift to lower corner frequency with increasing charge separation, and spectral scalloping. For charges closely spaced (up to 4 m, observed at 20 and 24 m), the primary effect on the waveform is replicated by a constant delay time between two identical waveforms. For charges spaced by 10 m (observed at 20 and 30 m), the effects of propagation path differences must be included. These effects result in smoothed spectra.

scholarly journals Experimental and analytical study of seismic site response of discontinuous permafrost

2016 ◽  
Vol 53 (9) ◽  
pp. 1363-1375 ◽  
Author(s):  
Behrang Dadfar ◽  
M. Hesham El Naggar ◽  
Miroslav Nastev
Keyword(s):  
Shear Wave ◽  
Site Response ◽  
Free Field ◽  
Frozen Soil ◽  
Shaking Table ◽  
Experimental Program ◽  
Small Scale ◽  
Seismic Site Response ◽  
Discontinuous Permafrost ◽  
Spectral Accelerations

Seismic site response of discontinuous permafrost is discussed. The presence of frozen ground in soil deposits can significantly affect their dynamic response due to stiffer conditions characterized by higher shear-wave velocities compared to unfrozen soils. Both experimental and numerical investigations were conducted to examine the problem. The experimental program included a series of 1g shaking table tests on small-scale models. Nonlinear numerical analyses were performed employing FLAC software. The numerical model was verified using the obtained experimental results. Parametric simulations were then conducted using the verified model to study variations of the free-field spectral accelerations (on top of the frozen and unfrozen soil blocks) with the scheme of frozen–unfrozen soil, and to determine the key parameters and their effects on seismic site response. Results show that spectral accelerations were generally higher in frozen soils than in unfrozen ones. It was found that the shear-wave velocity of the frozen soil as well as the assumed geometry of the blocks and their spacing have a significant impact on the site response.

scholarly journals Magnetosheath-cusp interface

2004 ◽  
Vol 22 (1) ◽  
pp. 183-212 ◽  
Author(s):  
S. Savin ◽  
L. Zelenyi ◽  
S. Romanov ◽  
I. Sandahl ◽  
J. Pickett ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Solar Wind ◽  
Magnetic Fields ◽  
Large Scale ◽  
Traditional Approach ◽  
Qualitative Difference ◽  
Small Scale ◽  
Nonlinear Phenomena ◽  
Solar Wind Interaction ◽  
Linear Superposition

Abstract. We advance the achievements of Interball-1 and other contemporary missions in exploration of the magnetosheath-cusp interface. Extensive discussion of published results is accompanied by presentation of new data from a case study and a comparison of those data within the broader context of three-year magnetopause (MP) crossings by Interball-1. Multi-spacecraft boundary layer studies reveal that in ∼80% of the cases the interaction of the magnetosheath (MSH) flow with the high latitude MP produces a layer containing strong nonlinear turbulence, called the turbulent boundary layer (TBL). The TBL contains wave trains with flows at approximately the Alfvén speed along field lines and "diamagnetic bubbles" with small magnetic fields inside. A comparison of the multi-point measurements obtained on 29 May 1996 with a global MHD model indicates that three types of populating processes should be operative: large-scale (∼few RE) anti-parallel merging at sites remote from the cusp; medium-scale (few thousandkm) local TBL-merging of fields that are anti-parallel on average; small-scale (few hundredkm) bursty reconnection of fluctuating magnetic fields, representing a continuous mechanism for MSH plasma inflow into the magnetosphere, which could dominate in quasi-steady cases. The lowest frequency (∼1–2mHz) TBL fluctuations are traced throughout the magnetosheath from the post-bow shock region up to the inner magnetopause border. The resonance of these fluctuations with dayside flux tubes might provide an effective correlative link for the entire dayside region of the solar wind interaction with the magnetopause and cusp ionosphere. The TBL disturbances are characterized by kinked, double-sloped wave power spectra and, most probably, three-wave cascading. Both elliptical polarization and nearly Alfvénic phase velocities with characteristic dispersion indicate the kinetic Alfvénic nature of the TBL waves. The three-wave phase coupling could effectively support the self-organization of the TBL plasma by means of coherent resonant-like structures. The estimated characteristic scale of the "resonator" is of the order of the TBL dimension over the cusps. Inverse cascades of kinetic Alfvén waves are proposed for forming the larger scale "organizing" structures, which in turn synchronize all nonlinear cascades within the TBL in a self-consistent manner. This infers a qualitative difference from the traditional approach, wherein the MSH/cusp interaction is regarded as a linear superposition of magnetospheric responses on the solar wind or MSH disturbances. Key words. Magnetospheric physics (magnetopause, cusp, and boundary layers) – Space plasma physics (turbulence; nonlinear phenomena)

Pre-Test and Analysis of a Reinforced Concrete Slab Subjected to Blast From a Non-Confined Explosive

2018 ◽  
pp. 272-287
Author(s):  
Fausto B. Mendonça ◽  
Girum S. Urgessa
Keyword(s):  
Dynamic Analysis ◽  
Large Scale ◽  
Concrete Slab ◽  
Wave Parameter ◽  
Experimental Program ◽  
Small Scale ◽  
Maximum Displacement ◽  
Reinforced Concrete Slab ◽  
Test Experiment ◽  
Rc Slabs

A large scale experimental program consisting of testing 10 RC slabs with different variations of concrete compressive strength, reinforcement ratio and retrofit was conducted in Brazil. As part of that test program, a small-scale blast pre-test setup and associated dynamic analysis were conducted in order to confirm the proper functioning of the blast test sensors (pressure gages, displacement meter and accelerometers). The results of the pre-test were compared with theoretical blast wave parameter predictions using established equations and maximum displacement predictions using simplified dynamic analysis. The pre-test experiment provided useful insights and was shown to be critical for the success of the subsequent large scale blast tests.

A Simple Procedure for the Prediction of the Collapse Pressure of Pipelines With Narrow and Long Corrosion Defects: Uncertainty and Sensibility Analysis

2018 ◽  
Author(s):  
Nara Oliveira ◽  
Theodoro Netto
Keyword(s):  
Simple Procedure ◽  
Experimental Tests ◽  
External Pressure ◽  
Experimental Program ◽  
Small Scale ◽  
Test Results ◽  
Collapse Pressure ◽  
Operational Conditions ◽  
Sensibility Analysis ◽  
Corrosion Defects

The collapse pressure of pipelines containing corrosion defects is usually predicted by deterministic methods, either numerically or through empirical formulations. The severity of each individual corrosion defect can be determined by comparing the differential pressure during operation with the estimated collapse pressure. A simple deterministic procedure for estimating the collapse pressure of pipes with narrow and long defects has been recently proposed by Netto (2010). This formulation was based on a combined small-scale experimental program and nonlinear numerical analyses accounting for different materials and defect geometries. However, loads and resistance parameters have uncertainties which define the basic reliability problem. These uncertainties are mailyrelated to the geometric and material parameters of the pipe and the operational conditions. This paper presents additional experimental tests on corroded pipes under external pressure. The collapse pressure calculated using the equation proposed by Netto (2010) is compared with this new set of experiments and also with test results available in open literature. These results are used to estimate the equation uncertainty. Finally, a sensitivity analysis is performed to identify how geometric parameters of the defects influence the reduction of collapse pressure.

scholarly journals Comparison of Shredded Tire Chips and Tire Crumbs as Packing Media in Trickling Filters

2007 ◽  
Vol 42 (4) ◽  
pp. 319-326 ◽  
Author(s):  
Bibek Mondal ◽  
Mustafa A. Warith ◽  
Stephen D. Burns
Keyword(s):  
Oxygen Demand ◽  
Thick Layer ◽  
Ammonia Nitrogen ◽  
Experimental Program ◽  
Small Scale ◽  
Trickling Filters ◽  
Tire Chips ◽  
Organic Removal ◽  
Stable Conditions ◽  
Tire Crumbs

Abstract A five stage study was conducted using two trickling filters, one with shredded tire chips (12 to 50 mm) and the other with tire crumbs (1.5 to 6.5 mm) as packing media, and both landfill leachate and synthetically prepared leachate, to evaluate treatment performance. Due to increased surface area and sorption capacity, compared with other materials, a thick layer of biomass developed over the surface of tire chips and crumbs and sloughed off after approximately 21 days. Biochemical oxygen demand, chemical oxygen demand, and ammonia nitrogen removal were in the range of 81 to 96%, 76 to 90%, and 15 to 68%, respectively, under stable conditions. Organic removal and total dissolved solids reduction from the leachate were well correlated, with the exception of when biomass sloughing caused an increase in the organic content. The trickling filter with tire crumb media exhibited a more consistent organic removal throughout the experimental program. Tire chips, being readily available, could be a better alternative to crushed stone or gravel as a packing media in trickling filters. Tire crumbs appeared to be promising for small scale treatment systems.

scholarly journals Experimental investigation of the wind direction influence on the cooling of photovoltaic panels integrated in double skin façades

2019 ◽  
Vol 111 ◽  
pp. 03045
Author(s):  
Sebastian Valeriu Hudișteanu ◽  
Cătalin George Popovici
Keyword(s):  
Experimental Investigation ◽  
Wind Tunnel ◽  
Wind Direction ◽  
Warm Season ◽  
Experimental Program ◽  
Small Scale ◽  
Transfer Coefficients ◽  
Photovoltaic Panels ◽  
Reference Velocity ◽  
Double Skin

The paper presents a wind tunnel experimental investigation of a small-scale building model (1:30). The main objective of the study is to determine the influence of the reference wind direction over the ventilation inside the double skin façade (DSF) channel. The analyzed system consists of a building equipped with photovoltaic panels as the exterior glazing of DSF. The tests were achieved by conceiving and implementation of an experimental program using a wind tunnel with atmospheric boundary layer. The aim is to determine with acceptable probability the velocities that can be reached in the ventilated façade channel during the warm season and to establish a correlation between the external reference velocity magnitude and direction and the velocity field generated inside the channel of the façade. Measurements were carried out for the reference wind speed, total, dynamic and static pressure both in the reference point and inside the façade channel. The results of the investigation highlighted the correlation between the velocity and direction of the reference wind and the dynamics of the air movement inside the double skin façade. The measurements showed that for the analyzed configuration of the double skin façade, there is an optimal wind direction that ensures the best cooling effect to photovoltaic panels. Also, the convective heat transfer coefficients were determined under these conditions. The decrease of the photovoltaic panel’s temperature determines a raise of its efficiency and generated power.

scholarly journals Wind tunnel study of natural ventilation of building integrated photovoltaics double skin façade

2018 ◽  
Vol 32 ◽  
pp. 01020 ◽  
Author(s):  
Sebastian Valeriu Hudişteanu ◽  
Cătălin George Popovici ◽  
Nelu-Cristian Cherecheş
Keyword(s):  
Wind Tunnel ◽  
Natural Ventilation ◽  
Cooling Effect ◽  
Experimental Program ◽  
Small Scale ◽  
Photovoltaic Panels ◽  
Building Integrated Photovoltaics ◽  
Building Model ◽  
Double Skin ◽  
Wind Influence

The paper presents a wind tunnel experimental analysis of a small-scale building model (1:30). The objective of the study is to determine the wind influence on the ventilation of a double skin façade channel (DSF) and the cooling effect over integrated photovoltaic panels. The tests were achieved by conceiving and implementation of an experimental program using a wind tunnel with atmospheric boundary layer. The effect of the wind over the ventilation of the horizontal channels of double skin façades is evaluated for different incident velocities. The results are generalized for the average steady state values of the velocities analysed. The experimental results put in evidence the correlation between the reference wind velocity and the dynamics of the air movement inside the double skin façade. These values are used to determine the convective heat transfer and the cooling effect of the air streams inside the channel upon the integrated photovoltaic panels. The decrease of the photovoltaic panels temperature determines a raise of 11% in efficiency and power generated.

Application of Nontransfer Type Plasma Heating Technology for Core-Material-Relocation Tests in Boiling Water Reactor Severe Accident Conditions

2018 ◽  
Vol 4 (2) ◽  
Author(s):  
Yuta Abe ◽  
Ikken Sato ◽  
Toshio Nakagiri ◽  
Akihiro Ishimi ◽  
Yuji Nagae
Keyword(s):  
Plasma Heating ◽  
Boiling Water ◽  
Severe Accident ◽  
Core Material ◽  
Experimental Program ◽  
Small Scale ◽  
Boiling Water Reactor ◽  
Water Reactor ◽  
X Ray ◽  
Heating Technology

A new experimental program using nontransfer (NTR) type plasma heating is under consideration in Japan Atomic Energy Agency (JAEA) to clarify the uncertainty on core-material relocation (CMR) behavior of boiling water reactor (BWR). In order to confirm the applicability of this new technology, authors performed preparatory plasma heating tests using small-scale test pieces (107 mm × 107 mm × 222 mm (height)). An excellent perspective in terms of applicability of the NTR plasma heating to melting high melting-temperature materials such as ZrO2 has been obtained. In addition, molten pool was formed at the middle height of the test piece indicating its capability to simulate the initial phase of core degradation behavior consistent with the real UO2 fuel PHEBUS fission products (FP) tests. Furthermore, application of electron probe micro-analyzer (EPMA), scanning electron microscope (SEM)/energy dispersive X-ray spectrometry (EDX), and X-ray computed tomography (CT) led to a conclusion that the pool formed consisted mainly of Zr with some concentration of oxygen which tended to be enhanced at the upper surface region of the pool. Based on these results, an excellent perspective in terms of applicability of the NTR plasma heating technology to the severe accident (SA) experimental study was obtained.

Low-Cycle Fatigue of Base-Plate-to-Shell Connection in Uplifting Liquid Storage Tanks Under Seismic Loading

2019 ◽  
Author(s):  
Giannoula Chatzopoulou ◽  
Spyros A. Karamanos
Keyword(s):  
Mechanical Response ◽  
Low Cycle Fatigue ◽  
Fatigue Cracking ◽  
Base Plate ◽  
Seismic Loading ◽  
Experimental Program ◽  
Small Scale ◽  
Cycle Fatigue ◽  
Seismic Safety ◽  
Welded Connection

Abstract Unanchored steel tanks, subjected to strong seismic loading, may exhibit base plate uplifting. Under repeated uplifting, the welded connection of the tank base plate with the tank shell (a fillet-welded connection) is subjected to strong cyclic deformation, involving reverse plastic loading, and this could lead to failure of the welded connection in the form of low-cycle fatigue cracking. In the present paper, an experimental program is described, supported by numerical finite-element simulations. The tests are aimed at investigating the mechanical response of small-scale welded specimens, representing the connection of the base plate with the tank shell, subjected to uplifting loading conditions. The research has been partially supported by European research project INDUSE-2-SAFETY, on the seismic safety and resilience of critical components in industrial plants.

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