scholarly journals What Can We Learn from Experiments? Understanding the Threats to the Scalability of Experimental Results

2017 ◽  
Vol 107 (5) ◽  
pp. 282-286 ◽  
Author(s):  
Omar Al-Ubaydli ◽  
John A. List ◽  
Dana L. Suskind
Keyword(s):  
Large Scale ◽  
Treatment Effects ◽  
Experimental Studies ◽  
Experimental Results ◽  
Small Scale ◽  
Sources Of Information ◽  
Common Occurrence

Policymakers often consider interventions at the scale of the population, or some other large scale. One of the sources of information about the potential effects of such interventions is experimental studies conducted at a significantly smaller scale. A common occurrence is for the treatment effects detected in these small-scale studies to diminish substantially in size when applied at the larger scale that is of interest to policymakers. This paper provides an overview of the main reasons for a breakdown in scalability. Understanding the principal mechanisms represents a first step toward formulating countermeasures that promote scalability.

Dynamics of a Large Scale Hydraulic Capsule Pipeline System

1999 ◽  
Vol 124 (1) ◽  
pp. 191-195 ◽  
Author(s):  
Hongliu Du ◽  
Satish S. Nair
Keyword(s):  
Large Scale ◽  
Control Method ◽  
Experimental Studies ◽  
Small Scale ◽  
Pipeline System ◽  
Centrifugal Pumps ◽  
Long Distance ◽  
Column Separation ◽  
In Series ◽  
Hydraulic Capsule Pipeline

The dynamics of a booster station, which is critical for the control of a novel, long distance, hydraulic capsule pipeline, is simulated mathematically for design studies and control of the hydraulic transients caused by the valve actuators in the system. Several modifications to the pump bypass station configuration of the booster station have been studied. With the objective of eliminating column separation and reducing flow reversals, a configuration with several centrifugal pumps connected in series, and a carefully sized air chamber is found to be a viable design. A valve control method is designed to eliminate column separation and the design results in acceptable flow reversal levels in the main pipe. The simulation results match with trends in limited experimental studies performed on a small scale experimental capsule pipeline system.

Limit Load Analysis of Pressurized Containers

2014 ◽  
Author(s):  
C. Sklorz ◽  
F. Otremba ◽  
F. Reich
Keyword(s):  
Finite Element ◽  
Flow Stress ◽  
Yield Strength ◽  
Large Scale ◽  
Limit Load ◽  
Experimental Results ◽  
Small Scale ◽  
Finite Element Calculations ◽  
Load Analysis ◽  
Design Pressure

Limit load analysis is a well known method to calculate the allowable design pressure of container components. A limit load of a pressurized container is achieved, when the stress of a wall and the flow stress are equal. In the following paper the transferability of limit load analysis from small scale tank containers up to large scale containers (railway tank) are investigated. Finite element calculations are carried out and compared with experimental results. It can be concluded that the limit load analysis works very well. Furthermore, the yield strength of the material should be used as flow stress.

INVESTIGATION INTO THE INFLUENCE OF IMPREGNATION ON PINE TIMBER COMBUSTION USING A CONE CALORIMETER AND LARGE SCALE TESTS

2011 ◽  
Vol 3 (3) ◽  
pp. 91-104 ◽  
Author(s):  
Jerzy Gałaj ◽  
Zbignev Karpovič ◽  
Waldemar Jaskółowski
Keyword(s):  
Cone Calorimeter ◽  
Large Scale ◽  
Experimental Studies ◽  
Fire Retardant ◽  
Full Scale ◽  
Lower Amount ◽  
Small Scale ◽  
Fire Retardants ◽  
Co Concentration ◽  
Piloted Ignition

Fire safety is one of the main requirements with respect to the regulations on the buildings involved into the category of human hazards. Human safety measures are applied equally to inhabitants, users, customers, spectators, etc., as well as to fire brigades taking part in the activities connected with rescue actions. Methods for emission research were applied to estimate thermo-kinetic parameters related to smoke and toxic gases. The methods fall into two types: full scale methods reflect fire conditions and small laboratory scale methods having a significantly lower degree of reflection. This paper presents the results of studies on the influence of BAK-1 and Flamasepas-2 fire retardants produced in Lithuania and applied for timber on the selected parameters of the fire environment. Experimental studies were conducted using a cone calorimeter (small scale) in the closed compartment equipped with measuring devices (full scale). The undertaken studies have demonstrated that considering some parameters, such as heat release rate (HRR), a positive effect of the lower amount of the released heat can be obtained. Unfortunately, in case of the major part of the studied parameters, including time to ignition, CO concentration and extinction parameter reflecting smokiness, worse results (shorter time, higher CO values and higher extinction coefficient) have been observed for the treated timber rather than for the non-impregnated one. The obtained results have showed combustion with piloted ignition. In case of no piloted ignition, the results were slightly different. For all studied specimens treated with fire retardants, no ignition was observed and tests were terminated following 15 minutes. CO concentration and extinction parameter (smokiness) were higher for non-impregnated timber. Full scale experiments have confirmed the above provided information; moreover, it has been found that the application of fire retardant has no significant impact on temperatures in the compartment.

Turbulent characteristics of a shallow wall-bounded plane jet: experimental implications for river mouth hydrodynamics

2009 ◽  
Vol 627 ◽  
pp. 423-449 ◽  
Author(s):  
JOEL C. ROWLAND ◽  
MARK T. STACEY ◽  
WILLIAM E. DIETRICH
Keyword(s):  
Large Scale ◽  
Experimental Studies ◽  
River Mouth ◽  
Experimental Results ◽  
Stream Velocity ◽  
Shear Stresses ◽  
Lateral Shear ◽  
Turbulent Structures ◽  
Turbulent Characteristics ◽  
Plane Jet

Jets arising from rivers, streams and tidal flows entering still waters differ from most experimental studies of jets both in aspect ratio and in the presence of a solid bottom boundary and an upper free surface. Despite these differences, the applicability of experimental jet studies to these systems remains largely untested by either field or realistically scaled experimental studies. Here we present experimental results for a wall-bounded plane jet scaled to jets created by flow discharging into floodplain lakes. A characteristic feature of both our prototype and experimental jets is the presence of large-scale meandering turbulent structures that span the width of the jets. In our experimental jets, we observe self-similarity in the distribution of mean streamwise velocities by a distance of six channel widths downstream of the jet outlet. After a distance of nine channel widths the velocity decay and the spreading rates largely agree with prior experimental results for plane jets. The magnitudes and distributions of the cross-stream velocity and lateral shear stresses approach self-preserving conditions in the upper half of the flow, but decrease in magnitude, and deviate from self-preserving distributions with proximity to the bed. The presence of the meandering structure has little influence on the mean structure of the jet, but dominates the jet turbulence. A comparison of turbulence analysed at time scales both greater than and less than the period of the meandering structure indicates that these structures increase turbulence intensities by 3–5 times, and produce lateral shear stresses and momentum diffusivities that are one and two orders of magnitude greater, respectively, than turbulence generated by bed friction alone.

Transient Modeling of a Capillary Pumped Loop for Terrestrial Applications

2016 ◽  
Vol 138 (7) ◽  
Author(s):  
Nicolas Blet ◽  
Vincent Platel ◽  
Vincent Ayel ◽  
Yves Bertin ◽  
Cyril Romestant
Keyword(s):  
Large Scale ◽  
Experimental Studies ◽  
Electronics Cooling ◽  
Industrial Applications ◽  
Experimental Results ◽  
Loop Heat Pipe ◽  
Electrical Networks ◽  
Balance Equations ◽  
Capillary Pumped Loop ◽  
Nodal Method

Improvement of a new design for a capillary pumped loop (CPL) ensuring high-dissipation electronics cooling in ground transportation has been carried out over recent years. Experimental studies on the hybrid loop, which share some characteristics with the standard CPL and loop heat pipe (LHP), have underlined the sizable potential of this new system, particularly with regard to its upcoming industrial applications. In order to obtain a reliable tool for sizing and design of this CPL for terrestrial applications (CPLTA), the present transient thermohydraulic modeling has been developed. Based on the nodal method, the model's originality consists of transcribing balance equations under electrical networks by analogy. The model's validation is provided by experimental results from a new CPLTA bench with three parallel evaporators. Large-scale numerical evaluation of loop behavior in a gravity field with a single evaporator shall facilitate understanding of the different couplings between loop parts. In addition, modeling of a multi-evaporator loop is introduced and compared with recent experimental results.

scholarly journals A MAPPING METHOD OF INTEGRATING MULTI-SCALE RIVER THEMATIC MAPS

2017 ◽  
Vol XLII-2/W7 ◽  
pp. 573-577
Author(s):  
W. Zhang ◽  
C. Yue ◽  
C. Cui ◽  
L. Meng
Keyword(s):  
Spatial Analysis ◽  
Large Scale ◽  
Mapping Method ◽  
Experimental Results ◽  
Small Scale ◽  
Thematic Maps ◽  
Fast Calculation ◽  
Thematic Map ◽  
Multi Scale ◽  
Scale Line

Small-scale maps are generally used in spatial analysis for fast calculation, but part of important features are missing due to its generalization level, which makes the analysis results less accurate. Therefore, it is necessary to improve feature completeness of smallscale maps. The goal of this paper is to put forward a mapping method of integrating the existing multi-scale river thematic maps. In order to achieve this goal, this paper proposed an algorithm for multi-scale line features matching by calculating the distance from node to polyline and an integrating algorithm by simplifying, shortening and merging the features from the original multi-scale thematic maps. The experimental results proved that the new map produced by the method proposed in this paper keeps the same scale as the original small-scale map and it is consistent with the original large-scale map in terms of feature completeness. The strategy proposed in this paper can be used to produce a new river thematic map concluding all the features that users need; moreover, the new map not only expresses features completely but also takes up less storage.

scholarly journals DIMPLE GENERATOR OF VORTEX STRUCTURES

2021 ◽  
pp. 95-102
Author(s):  
A. V. Voskobijnyk ◽  
V. M. Turick ◽  
O. A. Voskoboinyk ◽  
V. A. Voskoboinick
Keyword(s):  
Large Scale ◽  
Vortex Flow ◽  
Flat Surface ◽  
Pressure Fluctuations ◽  
Experimental Studies ◽  
Vortex Structures ◽  
Small Scale ◽  
Wall Pressure Fluctuations ◽  
Large Scale Vortex ◽  
Streamlined Surface

The paper presents the results of experimental studies of the space-time characteristics of the velocity and pressure field inside a hemispherical dimple on a flat surface. The features of the formation and development of vortex structures generated inside the dimple, as well as their interaction with the streamlined surface of the dimple and the boundary layer were established. Integral, spectral and correlation characteristics of the field of velocity, dynamic and wall pressure fluctuations were obtained. The velocities and directions of transfer of large-scale vortex structures and small-scale vortices inside the dimple were determined. The frequencies of rotations and ejections of large-scale vortices, the frequencies of oscillations of the vortex flow inside the dimple and self-oscillations of the vortex structures of the shear layer, their subharmonics and harmonics of higher orders were established.

Prediction of Welding-Induced Distortion of Fixed Plate Edge Using Design of Experiment Approach

2020 ◽  
Vol 27 (1) ◽  
pp. 134-142
Author(s):  
Tomasz Urbański ◽  
Andrzej Banaszek ◽  
Wojciech Jurczak
Keyword(s):  
Design Of Experiment ◽  
Large Scale ◽  
Experimental Studies ◽  
Steel Structures ◽  
Butt Joint ◽  
Experimental Results ◽  
Plate Edge ◽  
Shipbuilding Industry ◽  
Fixed Plate ◽  
Weld Distortion

AbstractThe paper presents the results of experimental studies on distortion of the fixed plate edge due to formation of a butt joint. This is a hidden form of weld distortion present in structural nodes and identified at the ship hull pre-fabrication stages. The investigations were performed according to a design of experiment (DoE) approach in laboratory conditions resembling those encountered in the shipbuilding industry. The presented analysis includes the technological–construction parameters influencing the evaluated distortion shape. The implemented method of experimental results evaluation allows the utilisation of the approximation dependence to predict the fixed plate edge distortion in large-scale steel structures.

Compressive Behavior of Large-Scale Hybrid FRP-Concrete-Steel Double-Skin Tubular Columns

2011 ◽  
Vol 243-249 ◽  
pp. 1138-1144 ◽  
Author(s):  
Pan Xie ◽  
T Yu ◽  
Y.L. Wong ◽  
J.G. Teng
Keyword(s):  
Large Scale ◽  
Experimental Studies ◽  
Steel Tube ◽  
Small Scale ◽  
Structural Members ◽  
Compression Tests ◽  
Tubular Columns ◽  
Compressive Response ◽  
Double Skin ◽  
Frp Tube

Hybrid FRP-concrete-steel double-skin tubular columns (DSTCs) are a new form of hybrid structural members. A hybrid DTSC consists of an inner steel tube, an outer FRP tube and a concrete infill between them. Hybrid DSTCs possess many important advantages over conventional structural members, including their excellent corrosion resistance as well as excellent ductility and seismic resistance. A large amount of research has been conducted on hybrid DSTCs, but the existing experimental studies have been limited to the testing of small-scale columns. This paper presents preliminary results from the first series of large-scale axial compression tests on hybrid DSTCs, which forms part of a larger experimental study currently under way at The Hong Kong Polytechnic University. These test results confirm the excellent axial compressive response of hybrid DSTCs as initially expected.

scholarly journals HYDRODYNAMICS UNDER LARGE-SCALE REGULAR AND BICHROMATIC BREAKING WAVES

2018 ◽  
pp. 90
Author(s):  
Dominic Van der A ◽  
Joep Van der Zanden ◽  
Ming Li ◽  
James Cooper ◽  
Simon Clark ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Surf Zone ◽  
Experimental Studies ◽  
Breaking Waves ◽  
Irregular Waves ◽  
Small Scale ◽  
Breaking Wave ◽  
Wave Flume ◽  
Cfd Models

Multiphase CFD models recently have proved promising in modelling cross‐shore sediment transport and morphodynamics (Jacobsen et al 2014). However, modelling breaking wave turbulence remains a major challenge for these models, because it occurs at very different spatial and temporal length scales and involves the interaction between surface generated turbulence and turbulence generated in the bottom boundary layer. To an extent these challenges arise from a lack of appropriate experimental data, since most previous experimental studies involved breaking waves at small-scale, and have not permitted investigation of the turbulent boundary layer processes. Moreover, most existing studies have concentrated on regular waves, thereby excluding the flow and turbulence dynamics occurring at wave group time-scales under irregular waves within the surf zone. These limitations motivated a new experiment in the large-scale CIEM wave flume in Barcelona involving regular and irregular waves. The experiment was conducted in May-July 2017 within the HYDRALAB+ Transnational Access project HYBRID.

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