scholarly journals Modeling SAOS Yield Stress of Cement Suspensions: Microstructure-Based Computational Approach

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2769
Author(s):  
Neven Ukrainczyk ◽  
Mareike Thiedeitz ◽  
Thomas Kränkel ◽  
Eddie Koenders ◽  
Christoph Gehlen
Keyword(s):  
Yield Stress ◽  
Critical Strain ◽  
Van Der Waals ◽  
Particle Interaction ◽  
High Sensitivity ◽  
Salient Feature ◽  
Model Parameters ◽  
Mathematical Tool ◽  
Interaction Forces ◽  
Small Amplitude Oscillatory Shear

Two static yield stress models, one known as YODEL and the newly proposed BreakPro, based on inter-particle bond breaking probability, were employed to comparatively simulate the yield stress of cement suspensions, induced by oscillatory rheological tests with small amplitude oscillatory shear (SAOS). This yield stress occurs at a critical strain in the order of 0.01%, and is commonly attributed to the limit of the linear viscoelastic domain, where attractive forces bridge the cement particles and form a flocculated particle network. YODEL is based on van der Waals (vdW) interaction forces to describe the yield stress for flow onset at a critical strain of a few percent, developed for simple non-reactive particulate suspensions. However, due to the high pH and reactivity of cementitious suspensions, their particle interaction forces are much higher than vdW. Therefore, until now, the YODEL adaptations to cementitious suspensions did not explicitly consider the microstructural-based salient feature of the original model, but used it as an implicit fitting parameter to scale the average attractive force. In this paper, the force is inversely estimated using the full power of the two microstructural-based models, presenting a new mathematical tool for investigating the fragility of the rigid percolated structure of cement suspensions. The model parameters were calibrated on measured yield stresses obtained by SAOS measurements in a high-sensitivity rheometer. The estimated forces were found to be 5.57 (BreakPro) and 1.43 (YODEL) times higher than typical van der Waals forces. The YODEL percolation threshold of 21% turned out to be significantly lower than the one found by the BreakPro model (37%). This indicated that BreakPro modeling assumptions are better suited for the description of yield stress at SAOS critical strain than the YODEL model.

scholarly journals Giant gauge factor of Van der Waals material based strain sensors

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wenjie Yan ◽  
Huei-Ru Fuh ◽  
Yanhui Lv ◽  
Ke-Qiu Chen ◽  
Tsung-Yin Tsai ◽  
...  
Keyword(s):  
Carrier Mobility ◽  
Large Range ◽  
Van Der Waals ◽  
High Sensitivity ◽  
Strain Sensors ◽  
Strain Gauges ◽  
Gauge Factor ◽  
Proof Of Concept ◽  
High Flexibility ◽  
Small Deformations

AbstractThere is an emergent demand for high-flexibility, high-sensitivity and low-power strain gauges capable of sensing small deformations and vibrations in extreme conditions. Enhancing the gauge factor remains one of the greatest challenges for strain sensors. This is typically limited to below 300 and set when the sensor is fabricated. We report a strategy to tune and enhance the gauge factor of strain sensors based on Van der Waals materials by tuning the carrier mobility and concentration through an interplay of piezoelectric and photoelectric effects. For a SnS2 sensor we report a gauge factor up to 3933, and the ability to tune it over a large range, from 23 to 3933. Results from SnS2, GaSe, GeSe, monolayer WSe2, and monolayer MoSe2 sensors suggest that this is a universal phenomenon for Van der Waals semiconductors. We also provide proof of concept demonstrations by detecting vibrations caused by sound and capturing body movements.

How the particle interaction forces determine soil water infiltration: Specific ion effects

2019 ◽  
Vol 568 ◽  
pp. 492-500 ◽  
Author(s):  
Wuquan Ding ◽  
Xinmin Liu ◽  
Feinan Hu ◽  
Hualing Zhu ◽  
Yaxue Luo ◽  
...  
Keyword(s):  
Soil Water ◽  
Particle Interaction ◽  
Water Infiltration ◽  
Interaction Forces ◽  
Specific Ion Effects ◽  
Soil Water Infiltration ◽  
Ion Effects

Separation-dependence evolution of inter-particle interaction in the oriented-attachment growth of nanorods: a case of hexagonal nanocrystals

The Analyst ◽  
2014 ◽  
Vol 139 (13) ◽  
pp. 3393-3397 ◽  
Author(s):  
Yuanqiang Song ◽  
Aifang Liu ◽  
Yu Pan ◽  
Xiaoning Wang ◽  
Jiarui Hu ◽  
...  
Keyword(s):  
Van Der Waals ◽  
Particle Interaction ◽  
Van Der Waals Interaction ◽  
Oriented Attachment ◽  
Coulombic Interaction ◽  
Hexagonal Nanorods

By focusing on hexagonal nanorods, the countering effects of van der Waals interaction and Coulombic interaction on the oriented attachment growth of 1D nanocrystals are investigated.

Influence of Forming and Flattening on the Measured Tensile Properties of Linepipe

2006 ◽  
Author(s):  
Philippe Thibaux ◽  
Dennis Van Hoecke ◽  
Gert De Vos
Keyword(s):  
Tensile Test ◽  
Tensile Properties ◽  
Yield Stress ◽  
Mechanical Behaviour ◽  
Base Material ◽  
Constitutive Laws ◽  
Pipe Production ◽  
Model Parameters ◽  
Deformation Path ◽  
Reverse Deformation

Steelmakers are producing plates or coils, which are subsequently formed into pipes. The mechanical properties are checked after steel and pipe production, and it is commonly observed that the tensile properties of pipes differ from the properties of plate or coil. The difference in tensile properties is attributed to the forming of the pipe and the subsequent flattening of a pipe section to make a flat tensile test sample. The reverse deformation during pipe forming and flattening is expected to cause a Bauschinger effect leading to a decrease of the yield stress of the pipe compared to the yield stress of the base material. First, a kinematics description of the pipe forming is presented. This kinematics description is important to know the deformation path followed by the material during pipe forming, flattening and tensile test. Once the deformation path is known, the stress state can be computed using constitutive laws. Three constitutive laws are presented here and their ability to describe the mechanical behaviour is further discussed. To determine the mechanical behaviour in reverse deformation paths, a specific experimental set-up has been developed to make reverse tests in tension and compression. Using this experimental facility, an X60 grade on coil has been characterized. Models parameters are fitted on the experimental data. Using these model parameters, a tensile test after forming and flattening is modelled. The simulation shows that a very accurate description of material behaviour is required to predict the final tensile properties.

scholarly journals First millimeter Mapping of the jet and nucleus of M87

1996 ◽  
Vol 175 ◽  
pp. 175-176
Author(s):  
V. Despringre ◽  
D. Fraix-Burnet
Keyword(s):  
Thermal Emission ◽  
Cutoff Frequency ◽  
Low Frequency ◽  
High Sensitivity ◽  
Model Parameters ◽  
Relativistic Electrons ◽  
Extragalactic Jets ◽  
Molecular Lines ◽  
Optical Wavelengths ◽  
Cold Dust

An intriguing question about extragalactic jets is why they are so few being seen at optical wavelengths, or equivalently, why the cutoff frequency of the synchrotron radiation is generally not in the optical, but rather in the infrared or even in the sub- millimeter domain. The answer is undoubtedly related to the efficiency of the acceleration of the relativistic electrons responsible for the synchrotron emission. The presence of a break at low frequency somewhere in the synchrotron spectrum is another feature that constrains the model parameters, but its precise location is unknown for most jets, because of the lack of photometry in the millimeter domain. It was thus necessary to fill the gap between radio and optical wavelengths in the synchrotron spectrum of optical jets. The required observation had to be of high sensitivity and high spatial resolution (of the order of 1″). Another reason for observing at millimeter wavelengths is that molecular lines and thermal emission from cold dust are detectable in this frequency range.

Reverse engineering of gene regulatory networks based on S-systems and Bat algorithm

2016 ◽  
Vol 14 (03) ◽  
pp. 1650010 ◽  
Author(s):  
Sudip Mandal ◽  
Abhinandan Khan ◽  
Goutam Saha ◽  
Rajat Kumar Pal
Keyword(s):  
Reverse Engineering ◽  
Gene Regulatory Networks ◽  
Regulatory Networks ◽  
Real Life ◽  
Bat Algorithm ◽  
Genetic Network ◽  
Model Parameters ◽  
Mathematical Tool ◽  
Gene Regulatory ◽  
Artificial Network

The correct inference of gene regulatory networks for the understanding of the intricacies of the complex biological regulations remains an intriguing task for researchers. With the availability of large dimensional microarray data, relationships among thousands of genes can be simultaneously extracted. Among the prevalent models of reverse engineering genetic networks, S-system is considered to be an efficient mathematical tool. In this paper, Bat algorithm, based on the echolocation of bats, has been used to optimize the S-system model parameters. A decoupled S-system has been implemented to reduce the complexity of the algorithm. Initially, the proposed method has been successfully tested on an artificial network with and without the presence of noise. Based on the fact that a real-life genetic network is sparsely connected, a novel Accumulative Cardinality based decoupled S-system has been proposed. The cardinality has been varied from zero up to a maximum value, and this model has been implemented for the reconstruction of the DNA SOS repair network of Escherichia coli. The obtained results have shown significant improvements in the detection of a greater number of true regulations, and in the minimization of false detections compared to other existing methods.

Evaluation of allergic response using dynamic thermography

2015 ◽  
Vol 23 (1) ◽  
Author(s):  
E. Rokita ◽  
T. Rok ◽  
G. Tatoń
Keyword(s):  
Allergic Reaction ◽  
Skin Prick Test ◽  
High Sensitivity ◽  
Allergic Response ◽  
Coefficient Of Determination ◽  
Model Parameters ◽  
Prick Test ◽  
Skin Reactivity ◽  
Heated Area ◽  
Spatio Temporal

AbstractSkin dynamic termography supplemented by a mathematical model is presented as an objective and sensitive indicator of the skin prick test result. Termographic measurements were performed simultaneously with routine skin prick tests. The IR images were acquired every 70 s up to 910 s after skin prick. In the model histamine is treated as the principal mediator of the allergic reaction. Histamine produces vasolidation and the engorged vessels are responsible for an increase in skin temperature. The model parameters were determined by fitting the analytical solutions to the spatio-temporal distributions of the differences between measured and baseline temperatures. The model reproduces experimental data very well (coefficient of determination = 0.805÷0.995). The method offers a set of parameters to describe separately skin allergic reaction and skin reactivity. The release of histamine after allergen injection is the best indicator of allergic response. The diagnostic parameter better correlates with the standard evaluation of a skin prick test (correlation coefficient = 0.98) than the result of the thermographic planimetric method based on temperature and heated area determination (0.81). The high sensitivity of the method allows for determination of the allergic response in patients with the reduced skin reactivity.

scholarly journals Parameter Optimization for Selected Correlation Analysis of Intracranial Pathophysiology

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Rupert Faltermeier ◽  
Martin A. Proescholdt ◽  
Sylvia Bele ◽  
Alexander Brawanski
Keyword(s):  
Correlation Analysis ◽  
Cerebral Autoregulation ◽  
High Sensitivity ◽  
Mathematical Tool ◽  
Time Resolved ◽  
Arterial Blood ◽  
Severe Impairment ◽  
Windowing Technique ◽  
Tool Set ◽  
Real Time Application

Recently we proposed a mathematical tool set, called selected correlation analysis, that reliably detects positive and negative correlations between arterial blood pressure (ABP) and intracranial pressure (ICP). Such correlations are associated with severe impairment of the cerebral autoregulation and intracranial compliance, as predicted by a mathematical model. The time resolved selected correlation analysis is based on a windowing technique combined with Fourier-based coherence calculations and therefore depends on several parameters. For real time application of this method at an ICU it is inevitable to adjust this mathematical tool for high sensitivity and distinct reliability. In this study, we will introduce a method to optimize the parameters of the selected correlation analysis by correlating an index, called selected correlation positive (SCP), with the outcome of the patients represented by the Glasgow Outcome Scale (GOS). For that purpose, the data of twenty-five patients were used to calculate the SCP value for each patient and multitude of feasible parameter sets of the selected correlation analysis. It could be shown that an optimized set of parameters is able to improve the sensitivity of the method by a factor greater than four in comparison to our first analyses.

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