Concrete anisotropy estimated from ultrasonic signal amplitudes

2021 ◽  
Vol 63 (12) ◽  
pp. 1164-1173
Author(s):  
Nevbahar Ekin
Keyword(s):  
Construction Industry ◽  
Shear Wave ◽  
Concrete Strength ◽  
Linear Regression Analysis ◽  
Fast Fourier Transformation ◽  
Essential Information ◽  
Degree Of Anisotropy ◽  
Transmission Measurements ◽  
First Time ◽  
Dominant Frequencies

Abstract The anisotropy of concrete is an essential issue in the construction industry. In this study, for the first time, ultrasonic compression and shear wave signals have been investigated for the orthogonal directions of unreinforced concrete by means of fast Fourier transformation (FFT). For this purpose, cubic concrete samples were prepared in 12 designs of different strengths for ultrasound transmission measurements. The characteristic amplitudes at dominant frequencies were determined by the FFT of these signals. The FFT amplitude differences in the compression and the shear wave signals on the orthogonally oriented surfaces provide essential information about the presence and degree of anisotropy. According to linear regression analysis, the FFT amplitude anisotropies and the amplitude ratios of the compression and shear waves decreased significantly according to increasing concrete strength. In addition, it was found that the anisotropy and the ratio of the FFT amplitudes increased proportionally to the water/cement ratio, the porosity and the water content of the various concrete designs.

scholarly journals Comparative Study of Chemical Compositions and Antioxidant Capacities of Oils Obtained from 15 Macadamia (Macadamia integrifolia) Cultivars in China

Foods ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1031
Author(s):  
Xixiang Shuai ◽  
Taotao Dai ◽  
Mingshun Chen ◽  
Ruihong Liang ◽  
Liqing Du ◽  
...  
Keyword(s):  
Palmitoleic Acid ◽  
Linear Regression Analysis ◽  
Monounsaturated Fatty Acids ◽  
Multiple Linear Regression Analysis ◽  
Chemical Compositions ◽  
Macadamia Integrifolia ◽  
Antioxidant Capacities ◽  
Squalene Content ◽  
First Time ◽  
Insight Into

The planting area of macadamia in China accounted for more than one third of the world’s planted area. The lipid compositions, minor components, and antioxidant capacities of fifteen varieties of macadamia oil (MO) in China were comparatively investigated. All varieties of MO were rich in monounsaturated fatty acids, mainly including oleic acid (61.74–66.47%) and palmitoleic acid (13.22–17.63%). The main triacylglycerols of MO were first time reported, including 19.2–26.1% of triolein, 16.4–18.2% of 1-palmitoyl-2,3-dioleoyl-glycerol, and 11.9–13.7% of 1-palmitoleoyl-2-oleoyl-3-stearoyl-glycerol, etc. The polyphenol, α-tocotrienol and squalene content varied among the cultivars, while Fuji (791) contained the highest polyphenols and squalene content. Multiple linear regression analysis indicated the polyphenols and squalene content positively correlated with the antioxidant capacity. This study can provide a crucial directive for the breeding of macadamia and offer an insight into industrial application of MO in China.

scholarly journals Diagnosis of experimental stetohepatosis using ultrasound shear wave elastography

2015 ◽  
Vol 26 (1) ◽  
pp. 109-113
Keyword(s):  
Insulin Resistance ◽  
Shear Wave ◽  
Shear Wave Elastography ◽  
Mixed Diet ◽  
Sweetened Condensed Milk ◽  
Non Invasive ◽  
Condensed Milk ◽  
First Time ◽  
Diagnosis Technique

According to available literature data, NAFLD may play crucial role in the pathogenesis of type 2 diabetes and other conditions connected with insulin resistance. In order to study the essence of the NAFLD, we have created an experimental model of the steatohepatosis. The mixed diet for 8 weeks consisting of standard food (47%), sweetened condensed milk (44%), vegetable oil (8%) and vegetable starch (1%) develops non-alcoholic steatohepatosis in the animals undergoing the experiment. The morphological signs of the non-alcoholic steatohepatosis comprised as follows in the hepatocytes of the rats undergoing the experiment: presence of fine-drop fattiness (fine-drop steatosis) and accumulation of fat vacuoles shifting the nucleus towards the cell peripheral. Substantial increase in the liver pulp of the animals undergoing the experiment defined using the ultrasound shear wave elastography technique is indicative of the presence of the non-alcoholic steatohepatosis. The ultrasound shear wave elastography technique can be used as a non-invasive diagnosis marker of the non-alcoholic steatohepatosis. The said diagnosis technique has been recommended for the first time.

scholarly journals The Proposition of an EI Equation of Square and L–Shaped Slender Reinforced Concrete Columns under Combined Loading

2021 ◽  
Vol 11 (3) ◽  
pp. 7100-7106
Author(s):  
L. Hamzaoui ◽  
T. Bouzid
Keyword(s):  
Reinforced Concrete ◽  
Axial Load ◽  
Concrete Strength ◽  
Linear Regression Analysis ◽  
Strain Curve ◽  
Load Level ◽  
Combined Loading ◽  
Actual Behavior ◽  
Factors Affecting ◽  
Slender Columns

The stability and strength of slender Reinforced Concrete (RC) columns depend directly on the flexural stiffness EI, which is a major parameter in strain calculations including those with bending and axial load. Due to the non-linearity of the stress-strain curve of concrete, the effective bending stiffness EI always remains variable. Numerical simulations were performed for square and L-shaped reinforced concrete sections of slender columns subjected to an eccentric axial force to estimate the variation of El resulting from the actual behavior of the column, based on the moment-curvature relationship. Seventy thousand (70000) hypothetical slender columns, each with a different combination of variables, were used to investigate the main variables that affect the EI of RC slender columns. Using linear regression analysis, a new simple and linear expression of EI was developed. Slenderness, axial load level, and concrete strength have been identified as the most important factors affecting effective stiffness. Finally, the comparison between the results of the new equation and the methods proposed by ACI-318 and Euro Code-2 was carried out in connection with the experimental results of the literature. A good agreement of the results was found.

scholarly journals Experimental evidence for foraminiferal calcification under anoxia

2014 ◽  
Vol 11 (14) ◽  
pp. 4029-4038 ◽  
Author(s):  
M. P. Nardelli ◽  
C. Barras ◽  
E. Metzger ◽  
A. Mouret ◽  
H. L. Filipsson ◽  
...  
Keyword(s):  
Environmental Variability ◽  
Sediment Cores ◽  
Adult Mortality ◽  
Short Term ◽  
Essential Information ◽  
Ample Evidence ◽  
Anoxic Conditions ◽  
Inhibition Of Growth ◽  
Foraminiferal Species ◽  
First Time

Abstract. Benthic foraminiferal tests are widely used for paleoceanographic reconstructions from a range of different environments with varying dissolved oxygen concentrations in the bottom water. There is ample evidence that foraminifera can live in anoxic sediments. For some species, this is explained by a switch to facultative anaerobic metabolism (i.e. denitrification). Here we show for the first time that adult specimens of three benthic foraminiferal species are not only able to survive, but are also able to calcify under anoxic conditions, at various depths in the sediment, and with or without nitrates. In fact, several specimens of Ammonia tepida (1–4%), Bulimina marginata (8–24%) and Cassidulina laevigata (16–23%) were able to calcify at different redox fronts of sediment cores, under laboratory conditions. This demonstrates ongoing metabolic processes, even in micro-environments where denitrification is not possible. Earlier observations suggest that the disappearance of foraminiferal communities after prolonged anoxia is not due to instantaneous or strongly increased adult mortality. Here we show that it cannot be explained by an inhibition of growth through chamber addition either. Our observations of ongoing calcification under anoxic conditions mean that geochemical proxy data obtained from benthic foraminifera in settings experiencing intermittent anoxia have to be reconsidered. The analysis of whole single specimens or of their successive chambers may provide essential information about short-term environmental variability and/or the causes of anoxia.

scholarly journals Analysing Enabling Factors Affecting the On-site Productivity in Indian Construction Industry

2018 ◽  
Vol 49 (2) ◽  
pp. 185-193 ◽  
Author(s):  
Saurav Dixit
Keyword(s):  
Regression Analysis ◽  
Linear Regression ◽  
Reliability Analysis ◽  
Construction Industry ◽  
Pearson Correlation ◽  
Linear Regression Analysis ◽  
Research Paper ◽  
Site Productivity ◽  
Factors Affecting ◽  
Construction Productivity

The growth in construction productivity is low and do not continue for a long span of time. The purpose of the present research paper is to analyse the factors affecting on-site construction productivity in Indian construction industry. The tools used for the analysis are reliability analysis to check the consistency of the data, Pearson correlation analysis to mathematically validate the factor analysis, and linear regression analysis to propose a framework of factors affecting construction productivity. The findings of the reliability analysis concludes that the all the factors having a value of more than 0.67, which is considered to be good for the study, and the findings of the study conclude that the most significant 3 attributes grouped in linear regression analysis change in scope (R2), revision in drawings (R15), and response to change orders (R3) having maximum impact over the construction productivity. The research paper attempts to provide an insight and better understanding of the factors affecting on-site construction productivity in India and the ways and means to control and improve construction productivity of construction projects."This paper is the revised version of the paper that has been published in the proceedings of the Creative Construction Conference 2018: Dixit, S., Mandal, S. N., Thanikal, J. V, & Saurabh, K. (2018). Critical Analysis of Factors Affecting the on-site Productivity in Indian Construction Industry, (July), 38–45. https://doi.org/10.3311/CCC2018-006"

Frequencies in vibrating wood – Does cell organization matter?

IAWA Journal ◽  
2019 ◽  
Vol 40 (1) ◽  
pp. 124-142
Author(s):  
Oliver Dünisch
Keyword(s):  
Spatial Organization ◽  
Ring Width ◽  
Spatial Arrangement ◽  
Cell Types ◽  
Dominant Frequency ◽  
Fast Fourier Transformation ◽  
Frequency Spectra ◽  
Laser Sensors ◽  
Vibrating Plates ◽  
Dominant Frequencies

ABSTRACT The relationship between the spatial organization of different cell types, of the xylem rays, and of the tree rings and the frequencies in vibrating softwoods and hardwoods was studied under controlled conditions. In total, the frequencies in 1007 standardized vibrating plates from 16 softwoods and 74 hardwoods were analysed using high resolution laser sensors (accuracy ± 0.02 μm, sampling frequency 30 kHz) for vibration measurements. Overlapping frequencies within the frequency spectra were identified by means of Fast Fourier Transformation analysis. With regard to the number of distinct frequencies within the spectra, four different vibration types were identified: type 1–one dominant frequency within the frequency spectra; type 2-two dominant frequencies within the frequency spectra; type 3-three dominant frequencies within the frequency spectra; type 4-no dominant frequencies within the frequency spectra. The presence of distinct frequencies was correlated with a highly organized spatial arrangement of tracheids in softwoods, with a storied arrangement of the xylem rays in hardwoods, and with low variation in tree-ring width in both softwoods and hardwoods. The grid size for repetition in these xylem structures influenced the frequencies of the vibrating wood in absolute numbers. The results indicate that the analysis of the anatomical structure of the wood can contribute to the grading of timber for its vibration characteristics, which is of special interest for the selection of resonance wood for musical instruments.

scholarly journals Identification of Water Hammering for Centrifugal Pump Drive Systems

2020 ◽  
Vol 10 (8) ◽  
pp. 2683 ◽  
Author(s):  
Nabanita Dutta ◽  
Kaliannan Palanisamy ◽  
Umashankar Subramaniam ◽  
Sanjeevikumar Padmanaban ◽  
Jens Bo Holm-Nielsen ◽  
...  
Keyword(s):  
Linear Regression ◽  
Predictive Control ◽  
Wave Attenuation ◽  
Control Method ◽  
Early Stage ◽  
Linear Regression Analysis ◽  
Fast Fourier Transformation ◽  
Negative Wave ◽  
Pumping System ◽  
Drive Systems

Water hammering is a significant problem in pumping systems. It damages the pipelines of the pump drastically and needs to identify with an intelligent method. Various conventional methods such as the method of characteristics and wave attenuation methods are available to identify water hammering problems, and the predictive control method is one of the finest and time-saving methods that can identify the anomalies in the system at an early stage such that the device can be saved from total damage and reduce energy loss. In this research, a machine learning (ML) algorithm has used for a predictive control method for the identification of water hammering problems in a pumping system with the help of simulations and experimental-based works. A linear regression algorithm has been used in this work to predict water hammering problems. The efficiency of the algorithm is almost 90% compared to other ML algorithms. Through a Vib Sensor app-based device at different pressures and flow rates, the velocity of the pumping system, a fluctuation between healthy and faulty conditions, and acceleration value at different times have been collected for experimental analysis. A fault created to analyze a water hammering problem in a pumping system by the sudden closing and opening of the valve. When the valve suddenly closed, the kinetic energy in the system changed to elastic resilience, which created a series of positive and negative wave vibrations in the pipe. The present work concentrates on the water hammering problem of centrifugal pumping AC drive systems. The problem is mainly a pressure surge that occurs in the fluid, due to sudden or forced stops of valves or changes in the direction and momentum of the fluid. Various experimental results based on ML tool and fast Fourier transformation (FFT) analysis are obtained with a Vib Sensor testbed set-up to prove that linear regression analysis is the less time-consuming algorithm for fault detection, irrespective of data size.

A system to impose prescribed homogenous strains on cultured cells

2001 ◽  
Vol 91 (4) ◽  
pp. 1600-1610 ◽  
Author(s):  
Christopher M. Waters ◽  
Matthew R. Glucksberg ◽  
Eugene P. Lautenschlager ◽  
Chyh-Woei Lee ◽  
Reed M. Van Matre ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cultured Cells ◽  
Large Strain ◽  
Mechanical Strain ◽  
Airway Epithelial Cells ◽  
Airway Epithelial ◽  
Degree Of Anisotropy ◽  
High Degree ◽  
Membrane Shape ◽  
First Time

There is presently significant interest in cellular responses to physical forces, and numerous devices have been developed to apply stretch to cultured cells. Many of the early devices were limited by the heterogeneity of deformation of cells in different locations and by the high degree of anisotropy at a particular location. We have therefore developed a system to impose cyclic, large-strain, homogeneous stretch on a multiwell surface-treated silicone elastomer substrate plated with pulmonary epithelial cells. The pneumatically driven mechanism consists of four plates each with a clamp to fix one edge of the cruciform elastomer substrate. Four linear bearings set at predetermined angles between the plates ensure a constant ratio of principal strains throughout the stretch cycle. We present the design of the device and membrane shape, the surface modifications of the membrane to promote cell adhesion, predicted and experimental measurements of the strain field, and new data using cultured airway epithelial cells. We present for the first time the relationship between the magnitude of cyclic mechanical strain and the extent of wound closure and cell spreading.

Variation of Concrete Strength with the Insertion of Carbon Nanotubes

2013 ◽  
Vol 818 ◽  
pp. 124-131
Author(s):  
Assed N. Haddad ◽  
Jorge F. de Morais ◽  
Ana Catarina J. Evangelista
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Construction Industry ◽  
Concrete Strength ◽  
Cement Composites ◽  
Deformation Properties ◽  
The Face ◽  
Non Destructive ◽  
Technological Community

Nanomaterials could change the face of modern construction because they are more resistant, more durable and have notable features. Concrete is a material widely used in construction industry worldwide. Carbon nanotube has been considered a new and outstanding material in nanoscience field with great potential application in the construction industry. The study presented in this paper, aims at assessing how carbon nanotubes can affect cement composites and so the concrete, in terms of microstructure and physical-mechanical properties. Three different ratios of carbon nanotubes have been searched: 0.20%, 0.40% and 0.60%. To evaluate the mechanical properties of the samples, destructive and non-destructive tests were carried out to obtain compressive strength, tensile strength by diametrical compression, dynamic modulus of elasticity as well as the determination of their deformation properties. This work also aims to motivate entrepreneurs and professionals in the sector of civil engineering on the advantages of the application of nanotechnology in construction, as well as providing information to the scientific and technological community in general.

Optical Response of Mixed Molybdenum Dichalcogenides for Solar Cell Applications Using the Modified Becke–Johnson Potential

2016 ◽  
Vol 71 (3) ◽  
pp. 213-223 ◽  
Author(s):  
Ushma Ahuja ◽  
Ritu Joshi ◽  
D.C. Kothari ◽  
Harpal Tiwari ◽  
K. Venugopalan
Keyword(s):  
Solar Cell ◽  
Dielectric Constants ◽  
Full Potential ◽  
Energy Bands ◽  
Absorption Coefficients ◽  
Augmented Plane Wave ◽  
Wave Technique ◽  
Degree Of Anisotropy ◽  
Dependent Absorption ◽  
First Time

AbstractEnergy bands and density of states (DOS) of mixed molybdenum dichalcogenides like MoS2, MoSeS, MoSe2, MoTe2, MoTeS, and MoTe0.5S1.5 are reported for the first time using the Tran–Blaha modified Becke–Johnson potential within full potential-linearised augmented plane wave technique. From the partial DOS, a strong hybridisation between the Mo-d and chalcogen-p states is observed below the Fermi energy EF. In addition, the dielectric constants, absorption coefficients, and refractivity spectra of these compounds have also been deduced. The integrated absorption coefficients derived from the frequency-dependent absorption spectra within the energy range of 0–4.5 eV show a possibility of using molybdenum dichalcogenides, particularly MoTe0.5S1.5, in solar cell applications. Birefringence and degree of anisotropy are also discussed using the data on refractivity and imaginary components of the dielectric constant.

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