On the use of lightweight mateials in small-scale mobile bed physical models

2013 ◽  
Vol 165 ◽  
pp. 1575-1580 ◽  
Author(s):  
Valentina Petruzzelli ◽  
Vicente Gracia Garcia ◽  
Francesc Xavier Gironella i Cobos ◽  
Antonio Felice Petrillo
Keyword(s):  
Physical Models ◽  
Small Scale ◽  
Mobile Bed

scholarly journals The application of computational fluid dynamics and small-scale physical models to assess the effects of operational practices on the risk to public health within large indoor swimming pools

2015 ◽  
Vol 13 (4) ◽  
pp. 939-952 ◽  
Author(s):  
Lowell Lewis ◽  
John Chew ◽  
Iain Woodley ◽  
Jeni Colbourne ◽  
Katherine Pond
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Disease Transmission ◽  
Time Frame ◽  
Physical Models ◽  
Microbial Pathogens ◽  
Small Scale ◽  
Swimming Pools ◽  
Policy Makers ◽  
Operational Practices

Swimming pools provide an excellent facility for exercise and leisure but are also prone to contamination from microbial pathogens. The study modelled a 50-m × 20-m swimming pool using both a small-scale physical model and computational fluid dynamics to investigate how water and pathogens move around a pool in order to identify potential risk spots. Our study revealed a number of lessons for pool operators, designers and policy-makers: disinfection reaches the majority of a full-scale pool in approximately 16 minutes operating at the maximum permissible inlet velocity of 0.5 m/s. This suggests that where a pool is designed to have 15 paired inlets it is capable of distributing disinfectant throughout the water body within an acceptable time frame. However, the study also showed that the exchange rate of water is not uniform across the pool tank and that there is potential for areas of the pool tank to retain contaminated water for significant periods of time. ‘Dead spots’ exist at either end of the pool where pathogens could remain. This is particularly significant if there is a faecal release into the pool by bathers infected with Cryptosporidium parvum, increasing the potential for waterborne disease transmission.

scholarly journals Measurement of three-dimensional displacement field in piled embankments using synchrotron X-ray tomography

2019 ◽  
Vol 56 (6) ◽  
pp. 885-892 ◽  
Author(s):  
Louis King ◽  
Abdelmalek Bouazza ◽  
Anton Maksimenko ◽  
Will P. Gates ◽  
Stephen Dubsky
Keyword(s):  
High Resolution ◽  
Imaging Techniques ◽  
Three Dimensional ◽  
Physical Models ◽  
Scale Model ◽  
Small Scale ◽  
Full Field ◽  
X Ray ◽  
Wide Range ◽  
Piled Embankments

The measurement of displacement fields by nondestructive imaging techniques opens up the potential to study the pre-failure mechanisms of a wide range of geotechnical problems within physical models. With the advancement of imaging technologies, it has become possible to achieve high-resolution three-dimensional computed tomography volumes of relatively large samples, which may have previously resulted in excessively long scan times or significant imaging artefacts. Imaging of small-scale model piled embankments (142 mm diameter) comprising sand was undertaken using the imaging and medical beamline at the Australian Synchrotron. The monochromatic X-ray beam produced high-resolution reconstructed volumes with a fine texture due to the size and mineralogy of the sand grains as well as the phase contrast enhancement achieved by the monochromatic X-ray beam. The reconstructed volumes were well suited to the application of digital volume correlation, which utilizes cross-correlation techniques to estimate three-dimensional full-field displacement vectors. The output provides insight into the strain localizations that develop within piled embankments and an example of how advanced imaging techniques can be utilized to study the kinematics of physical models.

scholarly journals Sinkhole collapse propagation studies through instrumented small-scale physical models

2020 ◽  
Vol 382 ◽  
pp. 71-76
Author(s):  
Maria Ferentinou
Keyword(s):  
Warning System ◽  
Physical Models ◽  
Critical Conditions ◽  
Small Scale ◽  
Optic Fiber ◽  
Fiber Sensors ◽  
Ground Collapse ◽  
Scale Models ◽  
Sinkhole Collapse ◽  
Fbg Sensors

Abstract. Sinkholes are common geohazards, frequently responsible for sudden catastrophic ground collapse. Thus, effective monitoring would allow for further understanding of the mechanism of occurrence of sinkholes and lead to the development of a potential early warning system to provide an alarm or a warning of incipient col-lapse. In the current study, fiber Bragg gratings (FBGs) were used to instrument reduced scale models, simulating a sinkhole event. The tests were conducted by embedding optic fiber sensors in the soil and inducing failure until critical conditions were reached. FBG sensors were manufactured in a single optic fiber cable. The measurements of small horizontal strains were recorded simultaneously and in various positions. Failure mechanism was found to relate to the backfill density, and compaction.

scholarly journals Detection of arterial wall abnormalities via Bayesian model selection

2018 ◽  
Author(s):  
Karen Larson ◽  
Clark Bowman ◽  
Costas Papadimitriou ◽  
Petros Koumoutsakos ◽  
Anastasios Matzavinos
Keyword(s):  
Parameter Estimation ◽  
Model Selection ◽  
Parallel Implementation ◽  
Real Data ◽  
Physical Models ◽  
Patient Specific ◽  
Small Scale ◽  
Tree Model ◽  
Arterial Tree ◽  
Flow Models

AbstractPatient-specific modeling of hemodynamics in arterial networks has so far relied on parameter estimation for inexpensive or small-scale models. We describe here a Bayesian uncertainty quantification framework which makes two major advances: an efficient parallel implementation, allowing parameter estimation for more complex forward models, and a system for practical model selection, allowing evidence-based comparison between distinct physical models. We demonstrate the proposed methodology by generating simulated noisy flow velocity data from a branching arterial tree model in which a structural defect is introduced at an unknown location; our approach is shown to accurately locate the abnormality and estimate its physical properties even in the presence of significant observational and systemic error. As the method readily admits real data, it shows great potential in patient-specific parameter fitting for hemodynamical flow models.

Resource Scalability at Wave Energy Test Sites

2014 ◽  
Author(s):  
Brendan Cahill
Keyword(s):  
Wave Energy ◽  
Energy Resource ◽  
Ocean Waves ◽  
Primary Objective ◽  
Full Scale ◽  
Physical Models ◽  
Small Scale ◽  
Marine Energy ◽  
Lake Washington ◽  
Guide Device

Harnessing the power of ocean waves offers enormous potential as a source of renewable energy. To date the technologies for capturing this resource, collectively known as wave energy converters (WECs), have yet to reach commercial viability and continued research and development efforts are required to move wave energy to the industrial scale. Integral to this process is ensuring that technologies progress along a staged development pathway; proving WEC concepts using small scale physical models in controlled settings such as laboratory wave tanks before eventually advancing to testing sub-prototype and full scale devices in real sea conditions. The primary objective of this research is to improve the understanding of how best to address the scaling of wave resource measurements and wave energy device power production when analyzing the results of sea-trials. This paper draws on measured data from three test sites; Galway Bay in Ireland, the Pacific Marine Energy Test Centre off the coast of Oregon, and Lake Washington, and assesses how accurately they recreate, at reduced scale, the conditions that commercial WEC installations are likely to encounter at exposed deployment locations. Appropriate techniques for extrapolating these results to predict the performance of commercial WECs at energy-rich locations on the west coasts of Ireland and the US are also demonstrated and discussed. The output from this research will be a set of protocols for addressing wave energy resource scalability to help guide device developers through this important stage of technology progression. Improved knowledge regarding resource scalability will allow for more streamlined progression of WEC concepts from wave tanks to sea-trials, and eventually to full-scale ocean deployment. It will also result in a reduced uncertainty about device power output and survivability, which are key drivers in determining the economic viability of projects.

scholarly journals Detection of arterial wall abnormalities via Bayesian model selection

2019 ◽  
Vol 6 (10) ◽  
pp. 182229
Author(s):  
Karen Larson ◽  
Clark Bowman ◽  
Costas Papadimitriou ◽  
Petros Koumoutsakos ◽  
Anastasios Matzavinos
Keyword(s):  
Parameter Estimation ◽  
Model Selection ◽  
Parallel Implementation ◽  
Real Data ◽  
Physical Models ◽  
Patient Specific ◽  
Small Scale ◽  
Tree Model ◽  
Arterial Tree ◽  
Flow Models

Patient-specific modelling of haemodynamics in arterial networks has so far relied on parameter estimation for inexpensive or small-scale models. We describe here a Bayesian uncertainty quantification framework which makes two major advances: an efficient parallel implementation, allowing parameter estimation for more complex forward models, and a system for practical model selection, allowing evidence-based comparison between distinct physical models. We demonstrate the proposed methodology by generating simulated noisy flow velocity data from a branching arterial tree model in which a structural defect is introduced at an unknown location; our approach is shown to accurately locate the abnormality and estimate its physical properties even in the presence of significant observational and systemic error. As the method readily admits real data, it shows great potential in patient-specific parameter fitting for haemodynamical flow models.

scholarly journals Super-resolution emulator of cosmological simulations using deep physical models

2020 ◽  
Vol 495 (4) ◽  
pp. 4227-4236 ◽  
Author(s):  
Doogesh Kodi Ramanah ◽  
Tom Charnock ◽  
Francisco Villaescusa-Navarro ◽  
Benjamin D Wandelt
Keyword(s):  
Large Scale ◽  
Initial Conditions ◽  
Computational Cost ◽  
Physical Modelling ◽  
Real Space ◽  
Physical Models ◽  
Small Scale ◽  
Cosmological Simulations ◽  
Scale Structures ◽  
Small Scale Structures

ABSTRACT We present an extension of our recently developed Wasserstein optimized model to emulate accurate high-resolution (HR) features from computationally cheaper low-resolution (LR) cosmological simulations. Our deep physical modelling technique relies on restricted neural networks to perform a mapping of the distribution of the LR cosmic density field to the space of the HR small-scale structures. We constrain our network using a single triplet of HR initial conditions and the corresponding LR and HR evolved dark matter simulations from the quijote suite of simulations. We exploit the information content of the HR initial conditions as a well-constructed prior distribution from which the network emulates the small-scale structures. Once fitted, our physical model yields emulated HR simulations at low computational cost, while also providing some insights about how the large-scale modes affect the small-scale structure in real space.

Investgation of the geometric characteristics of a floating bilevel packaged rafting unit

2016 ◽  
Author(s):  
С.В. Посыпанов
Keyword(s):  
Closed Form Solution ◽  
Forest Products ◽  
Strength Properties ◽  
Form Solution ◽  
Physical Models ◽  
Shell Structures ◽  
Small Scale ◽  
Theoretical Investigations ◽  
Specialized Equipment ◽  
Geometric Elements

Технологии, связанные с формированием двухярусных пакетных сплоточных единиц, перспективны при организации транспорта лесоматериалов по средним и малым рекам. Также они могут быть интересны лесозаготовителям, для которых приобретение специализированной сплоточной техники нецелесообразно или невозможно. Для обеспечения возможности выполнения технологических и прочностных расчетов, связанных с указанными единицами, необходимы сведения о взаимозависимостях их геометрических характеристик. Для получения нужной информации использовали эластиковую теорию. При этом пакеты, составляющие сплоточную единицу, представляли как гибкие невесомые оболочки, заполненные сыпучими средами, находящимися под воздействием сил тяжести и Архимеда. Обвязки нижних пакетов рассматривали как бесперегибные эластики второго рода, обвязки верхних – как комбинации фрагментов двух таких эластик: подводной и надводной. Используя параметрические уравнения указанных кривых, получили замкнутую систему уравнений, отражающих зависимости искомых геометрических характеристик от модулярных углов, параметров эластик и модулярных высот, измерение которых на практике проблематично. Из-за присутствия в системе эллиптических интегралов ее аналитическое решение, обеспечивающее возможность выражения одних общепринятых характеристик через другие используемые на практике параметры оказалось невозможным. Предложили свой алгоритм численного решения системы, реализовали его на компьютере, выполнили соответствующие расчеты. При этом задача была сведена к безразмерному виду с целью уменьшения объема вычислений и обеспечения универсальности их результатов. Опираясь на материалы ранее проведенных исследований, связали значения вычисленных характеристик рассматриваемой сплоточной единицы с соответствующими геометрическими параметрами отдельных пакетов, составляющих ее, при нахождении их на суше или наплаву. Используя результаты выполненных вычислений, получили аппроксимирующие зависимости для сравнительно простого определения искомых геометрических характеристик при практических расчетах и дальнейших научных исследованиях. Установили характер и степень влияния определяющих факторов на указанные характеристики. Достоверность результатов теоретических исследований подтвердили в ходе экспериментальной проверки на моделях. Technologies of forming ofbilevel packaged rafting units are perspective for arrangement of transportation of forest products along the small and medium-scale rivers.Those technologies are potentially useful for small-scale loggers, who are not capable to purchase specialized equipment for rafts forming. The geometric and strength properties of the rafting units are necessary for implementation of relevant technological and strengthening estimations. In order to obtain required information, the elasticity theory was applied. The log packages were considered as flexible shell structures filled up with granular material, effected by gravity and Archimedes forces. The lower packages strappings were deemed as non-inflective second order elasticity, the upper ones – as combinations of fragments of underwater andoverwater elasticities. The circuit system of equations was developed to describe dependence of geometric elements on the elasticities parameters, modular angles and elevations, practical metering of which is problematic.The system contains the elliptical integrals, so the closed form solution was found impossible. The author’s algorithm of a numerical solution of the system is proposed and instrumented. Computations were carried outwithin the practical data span in adimensionless form. Based on the results of the previous studies, the parameters of a rafting unit was associated with the latter of log packages for afloat and ashore positions. The approximating dependencies for theoretical investigations and practical activities were developed. The reliability of estimates was proved via the physical models experiments.

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