A Numerical Investigation Into the Bottom Boundary Effect for Spudcan Penetration on Sand Overlying Clay in Centrifuge Test

2012 ◽  
Author(s):  
Shah Neyamat Ullah ◽  
Yuxia Hu
Keyword(s):  
Layer Thickness ◽  
Large Scale ◽  
Boundary Effect ◽  
Small Strain ◽  
Sand Layer ◽  
Centrifuge Test ◽  
Bottom Boundary ◽  
Centrifuge Testing ◽  
Soil Failure ◽  
Large Scale Testing

In the last two decades centrifuge testing of geomaterials to meet offshore design has gained momentum. In the absence of large scale testing this technique with all its versatility has been successfully used for many offshore applications encompassing spudcan foundation, anchors, caissons, piles etc. Although many real soil failure characteristics can be replicated in the centrifuge, the centrifuge strong box may constrain the testing range when large displacement of spudcan foundation needs to be tested, especially in multiple layer soils. The paper investigates the rigid bottom boundary effect of the centrifuge strong box during large penetration of spudcan foundation into sand over clay soil profiles. Large deformation finite element (LDFE) method incorporating RITSS (Remeshing and Interpolation Technique using Small Strain) approach has been adopted for numerical simulation of the problem. With fixed vertical space available, the effects of sand layer thickness, sand friction and dilation angles have been studied. The LDFE/RITSS method was validated by existing centrifuge test data. It was observed that, during spudcan penetration, the development of sand plug trapped beneath the spudcan played a crucial role in the bottom boundary effect. The boundary effect started earlier when the ratio of sand layer thickness to spudcan diameter was greater than unity.

A Database for the Experimental Study of Earthquake-Induced Liquefaction and Lateral Spreading in Sands

2016 ◽  
Vol 32 (2) ◽  
pp. 1261-1279
Author(s):  
Tarek Abdoun ◽  
Waleed El-Sekelly ◽  
Ricardo Dobry ◽  
Sabanayagam Thevanayagam ◽  
Marcelo Gonzalez
Keyword(s):  
Large Scale ◽  
Rensselaer Polytechnic Institute ◽  
Lateral Spreading ◽  
Soil Behavior ◽  
Centrifuge Testing ◽  
Geotechnical Centrifuge ◽  
Testing Facility ◽  
Large Scale Testing ◽  
Materials Used ◽  
The University

Centrifuge and large-scale testing in geotechnical engineering are very useful tools for modeling soil behavior under different loading conditions, particularly under earthquake loading. The paper presents an extensive database of nine centrifuge and large-scale liquefaction experiments performed both at the geotechnical centrifuge testing facility at Rensselaer Polytechnic Institute (RPI) and the large-scale testing facility at the University at Buffalo (UB). The database described herein was generated using the NEEShub online DataStore tool under the name “CENSEIS: Centrifuge and Large (Full)-Scale Modeling of Seismic Pore Pressures in Sands” (DOI: http://dx.doi.org/10.4231/D3GF0MX4F ). The paper discusses the tools and materials used in the experiments along with an explanation of each item in the database. Sample analyses are also presented in the paper to give an insight on the capabilities of the database for numerical and analytical applications. The paper is concluded with some possible applications along with tips and limitations of the database.

Effect of Underlying Sand Layer on Undrained Capacity of Spudcan Foundations in Soft Clay Under Combined Loading

2018 ◽  
Author(s):  
Yifa Wang ◽  
Mark J. Cassidy ◽  
Britta Bienen
Keyword(s):  
Soft Clay ◽  
Three Dimensional ◽  
Small Strain ◽  
Combined Loading ◽  
Sand Layer ◽  
Element Analysis ◽  
Moment Capacity ◽  
Soil Failure ◽  
Failure Envelopes ◽  
Vertical Bearing

During the operational phase, the spudcan foundations of a mobile jack-up rig are subjected to combined vertical, horizontal and moment loading. Although previous research has indicated a substantial increase in vertical bearing capacity when a spudcan penetrates through a soft clay layer towards a sand layer, the response of spudcan foundations subjected to combined loadings in such stratification has yet to be understood. This study investigates the effect of the underlying stronger sand layer on the undrained VHM capacity of a spudcan foundation using three-dimensional small-strain finite element analysis. Results show the significant increase in vertical and moment capacity, whereas the horizontal capacity is minimally affected. The soil failure mechanisms are identified and changes in the size and shape of failure envelopes, accounting for the sand layer underneath, are quantified. An analytical expression is proposed to predict the combined capacity of a spudcan foundation in clay overlying sand.

Methodology for Evaluating Inlet Protection Practices Using Large-Scale Testing Techniques

2015 ◽  
Vol 20 (4) ◽  
pp. 04014049 ◽  
Author(s):  
M. A. Perez ◽  
W. C. Zech ◽  
W. N. Donald ◽  
X. Fang
Keyword(s):  
Large Scale ◽  
Large Scale Testing ◽  
Testing Techniques

scholarly journals Direct detection of SARS-CoV-2 using non-commercial RT-LAMP reagents on heat-inactivated samples

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alisa Alekseenko ◽  
Donal Barrett ◽  
Yerma Pareja-Sanchez ◽  
Rebecca J. Howard ◽  
Emilia Strandback ◽  
...  
Keyword(s):  
Large Scale ◽  
Direct Detection ◽  
Dna Polymerases ◽  
Scale Up ◽  
Lamp Assay ◽  
Cost Effective ◽  
Reaction Conditions ◽  
Clinical Patient ◽  
Reverse Transcriptases ◽  
Large Scale Testing

AbstractRT-LAMP detection of SARS-CoV-2 has been shown to be a valuable approach to scale up COVID-19 diagnostics and thus contribute to limiting the spread of the disease. Here we present the optimization of highly cost-effective in-house produced enzymes, and we benchmark their performance against commercial alternatives. We explore the compatibility between multiple DNA polymerases with high strand-displacement activity and thermostable reverse transcriptases required for RT-LAMP. We optimize reaction conditions and demonstrate their applicability using both synthetic RNA and clinical patient samples. Finally, we validate the optimized RT-LAMP assay for the detection of SARS-CoV-2 in unextracted heat-inactivated nasopharyngeal samples from 184 patients. We anticipate that optimized and affordable reagents for RT-LAMP will facilitate the expansion of SARS-CoV-2 testing globally, especially in sites and settings where the need for large scale testing cannot be met by commercial alternatives.

Selection and Substantiation of Methods for Evaluating Cosmetic Products for Deodorant and Antiperspirant Action

2021 ◽  
Vol 37 (2) ◽  
pp. 54-64
Author(s):  
D.V. Barabash ◽  
I.A. Butorova
Keyword(s):  
Large Scale ◽  
Gravimetric Method ◽  
Population Data ◽  
Diffusion Method ◽  
Disc Diffusion ◽  
Disc Diffusion Method ◽  
Large Scale Testing ◽  
Sweat Secretion ◽  
Microbiological Methods ◽  
Number Of Microorganisms

The possibility of using simple and available methods for analyzing deodorants/antiperspirants has been studied. The gravimetric method was shown to have acceptable metrological characteristics under repeatability conditions when evaluating antiperspirant activity. A decrease in the number of microorganisms (CFU) on the axilla skin was observed in a rinse test experiment 4 h and 8 h after the application of deodorants/antiperspirants. The microbial population data were inversely proportional to the antiperspirant activity values of the tested compositions. The sweat secretion reducing decreases the amount of nutrients required for microbial development, which makes it possible to use the rinse test to indirectly evaluate deodorant activity in research and development of personal care products. However, due to its laboriousness and the need for volunteers, the method cannot be recommended for large-scale testing. It was shown that the disc diffusion method (DDM) used to detect Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus subtilis cannot be applied to the assessment of the intrinsic antimicrobial activity of the tested cosmetic compositions. This indicates the necessity of additional studies to select test microorganisms typical for the armpit area. In addition, DDM is useful if the deodorant effect of the composition is created by the addition of low-volatile antibacterial compounds. Therefore, microbiological methods have limited applications and are not suitable for widespread use. deodorant action; antiperspirant action, gravimetry, disc diffusion method, rinse test; deodorant; antiperspirant; cosmetic; efficiency; consumer properties, functional properties This work was supported by MUCTR (project no. K-2020-007).

The structure of a highly decelerated axisymmetric turbulent boundary layer

2021 ◽  
Vol 929 ◽  
Author(s):  
N. Agastya Balantrapu ◽  
Christopher Hickling ◽  
W. Nathan Alexander ◽  
William Devenport
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Shear Layer ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Large Scale ◽  
Convection Velocity ◽  
Mean Flow ◽  
Mean Velocity ◽  
The Mean

Experiments were performed over a body of revolution at a length-based Reynolds number of 1.9 million. While the lateral curvature parameters are moderate ( $\delta /r_s < 2, r_s^+>500$ , where $\delta$ is the boundary layer thickness and r s is the radius of curvature), the pressure gradient is increasingly adverse ( $\beta _{C} \in [5 \text {--} 18]$ where $\beta_{C}$ is Clauser’s pressure gradient parameter), representative of vehicle-relevant conditions. The mean flow in the outer regions of this fully attached boundary layer displays some properties of a free-shear layer, with the mean-velocity and turbulence intensity profiles attaining self-similarity with the ‘embedded shear layer’ scaling (Schatzman & Thomas, J. Fluid Mech., vol. 815, 2017, pp. 592–642). Spectral analysis of the streamwise turbulence revealed that, as the mean flow decelerates, the large-scale motions energize across the boundary layer, growing proportionally with the boundary layer thickness. When scaled with the shear layer parameters, the distribution of the energy in the low-frequency region is approximately self-similar, emphasizing the role of the embedded shear layer in the large-scale motions. The correlation structure of the boundary layer is discussed at length to supply information towards the development of turbulence and aeroacoustic models. One major finding is that the estimation of integral turbulence length scales from single-point measurements, via Taylor's hypothesis, requires significant corrections to the convection velocity in the inner 50 % of the boundary layer. The apparent convection velocity (estimated from the ratio of integral length scale to the time scale), is approximately 40 % greater than the local mean velocity, suggesting the turbulence is convected much faster than previously thought. Closer to the wall even higher corrections are required.

Trust, efficacy and ethicacy when testing prisoners for COVID-19

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Steve Lambert ◽  
Dean Wilkinson
Keyword(s):  
Large Scale ◽  
Current System ◽  
Epidemiological Studies ◽  
Careful Consideration ◽  
Power Relationships ◽  
England And Wales ◽  
Content Type ◽  
Large Scale Testing ◽  
The Uk ◽  
The Impact

Purpose The outbreak of the severe acute respiratory syndrome coronavirus 2 virus and subsequent COVID-19 illness has had a major impact on all levels of society internationally. The extent of the impact of COVID-19 on prison staff and prisoners in England and Wales is unknown. Testing for COVID-19 both asymptomatic and symptomatic, as well as for antibodies, to date, has been minimal. The purpose of this paper is to explore the widespread testing of COVID-19 in prisons poses philosophical and ethical questions around trust, efficacy and ethicacy. Design/methodology/approach This paper is both descriptive, providing an overview of the widespread testing of COVID-19 in prisoners in England and Wales, and conceptual in that it discusses and argues the issues associated with large-scale testing. This paper provides a discussion, using comparative studies, of the issues associated with large-scale testing of prisoners across the prison estate in England and Wales (120 prisons). The issues identified in this paper are contextualised through the lens of COVID-19, but they are equally transferrable to epidemiological studies of any pandemic. Given the prevalence of COVID-19 globally and the lack of information about its spread in prisons, at the time of writing this paper, there is a programme of asymptomatic testing of prisoners. However, there remains a paucity of data on the spread of COVID-19 in prisons because of the progress with the ongoing testing programme. Findings The authors argue that the widespread testing of prisoners requires careful consideration of the details regarding who is included in testing, how consent is gained and how tests are administered. This paper outlines and argues the importance of considering the complex nuance of power relationships within the prison system, among prisoner officers, medical staff and prisoners and the detrimental consequences. Practical implications The widespread testing of COVID-19 presents ethical and practical challenges. Careful planning is required when considering the ethics of who should be included in COVID-19 testing, how consent will be gained, who and how tests will be administered and very practical challenges around the recording and assigning of COVID-19 test kits inside the prison. The current system for the general population requires scanning of barcodes and registration using a mobile number; these facilities are not permitted inside a prison. Originality/value This paper looks at the issues associated with mass testing of prisoners for COVID-19. According to the authors’ knowledge, there has not been any research that looks at the issues of testing either in the UK or internationally. The literature available details countries’ responses to the pandemic rather and scientific papers on the development of vaccines. Therefore, this paper is an original review of some of the practicalities that need to be addressed to ensure that testing can be as successful as possible.

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