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Advanced Field Investigations of Screw Piles and Columns / Zaawansowane Badania Terenowe Pali I Kolumn Wkrecanych

Abstract

Field investigations concerning screw piles and columns have been carried out for the “Bearing capacity and work in the soil of screw piles” research project, financed by the Polish Ministry of Science and Higher Education - project No N N506 369234. The tests of three instrumented screw piles were conducted together with CPTU tests and measurements of pile installation parameters (especially torque). The objectives of field investigations and the entire research project include discovering how screw piles work in the soil, locating and describing the correlations between CPTU results and rotation resistance during pile auger installation and next establishing correlations between CPTU results, rotation resistance and the bearing capacity of this kind of piles. The paper describes the investigation procedure and the basic results of tests carried out in the first of a series of sites.

Open access
Methods for Determination of Mean Speckle Size in Simulated Speckle Pattern

References [1] Dainty, J.C. (ed.) (1984). Laser Speckle and Related Phenomena (2nd ed.). Springer-Verlag. [2] Lehmann, P. (1999). Surface-roughness measurement based on the intensity correlation function of scattered light under speckle-pattern illumination. Applied Optics, 38 (7), 1144-1157. [3] Chicea, D. (2007). An alternative algorithm to calculate the biospeckle size in coherent light scattering experiments. Romanian Journal of Physics, 54 (1-2), 147-155. [4] Piederriere, Y., Meur, J

Open access
Determination of Radiative Heat Transfer Coefficient at High Temperatures Using a Combined Experimental-Computational Technique

Abstract

The radiative heat transfer coefficient at high temperatures is determined using a combination of experimental measurement and computational modeling. In the experimental part, cement mortar specimen is heated in a laboratory furnace to 600°C and the temperature field inside is recorded using built-in K-type thermocouples connected to a data logger. The measured temperatures are then used as input parameters in the three dimensional computational modeling whose objective is to find the best correlation between the measured and calculated data via four free parameters, namely the thermal conductivity of the specimen, effective thermal conductivity of thermal insulation, and heat transfer coefficients at normal and high temperatures. The optimization procedure which is performed using the genetic algorithms provides the value of the high-temperature radiative heat transfer coefficient of 3.64 W/(m2K).

Open access
Measurement of nanopatterned surfaces by real and reciprocal space techniques

Measurement of nanopatterned surfaces by real and reciprocal space techniques

A newly developed laboratory grazing-incidence small-angle X-ray scattering GISAXS system capable of statistical measurements of surface morphology at the nanometer scale was developed. The potential of the GISAXS system is compared to the AFM technique for a nanopatterned silicon surface produced by ion-beam erosion. The characteristic period of the ion-beam induced ripples and their lateral correlation length were estimated from AFM. Using GISAXS the reciprocal space map of surface morphology was measured and analyzed. The two microfocus X-ray sources emitting radiation at the Cu-Kα and Cr-Kα were used. The lateral periods of ripples obtained by the reciprocal space mapping techniques match the results of real space techniques. The setup has the potential to monitor and control the deposition process and formation of nanostructures with sufficient temporal and spatial resolution.

Open access
Statistical Analysis of Spectral Properties and Prosodic Parameters of Emotional Speech

Statistical Analysis of Spectral Properties and Prosodic Parameters of Emotional Speech

The paper addresses reflection of microintonation and spectral properties in male and female acted emotional speech. Microintonation component of speech melody is analyzed regarding its spectral and statistical parameters. According to psychological research of emotional speech, different emotions are accompanied by different spectral noise. We control its amount by spectral flatness according to which the high frequency noise is mixed in voiced frames during cepstral speech synthesis. Our experiments are aimed at statistical analysis of cepstral coefficient values and ranges of spectral flatness in three emotions (joy, sadness, anger), and a neutral state for comparison. Calculated histograms of spectral flatness distribution are visually compared and modelled by Gamma probability distribution. Histograms of cepstral coefficient distribution are evaluated and compared using skewness and kurtosis. Achieved statistical results show good correlation comparing male and female voices for all emotional states portrayed by several Czech and Slovak professional actors.

Open access
Ultrasonic Quality Assessment of Polymer-Cement Concrete with Pet Waste as the Aggregate

Abstract

Elaborating composites containing waste materials requires study of basic mechanical properties and assessment of their structure quality. The subject of investigation was PPC concrete where aggregate was substituted with PET remaining after beverages bottles grinding. Substitution was done up to 25% (by volume). Waste material was fractioned and applied in various granulations. The main goal was to indicate the influence of such modification on the composite mechanical properties and to examine composite structure quality at macro level. Since PET and quartz differ greatly in density, to perform such examination it was possible to apply the nondestructive ultrasonic method, one of the most common NDT techniques used in material science and industry. The paper presents the effects of substitution of quartz with PET on ultrasonic wave propagation in PCC. The ultrasonic test results (measurements of wave velocity) compared with results of destructive tests (flexural and compressive strength) showed great correlation.

Open access
Tissue Morphology and Cell Impedance Based Biosensors for Toxicity Testing

References Ďaďo, S., Mandys, V., Šmíd, R. (2001). Biomedical shape measurement for neurotoxicity testing. Measurement Science Review , 1 (1), 55-58. Ďaďo, S., Šmíd, R. (1998). Characterization of an object shape in the picture using continuous wavelet transform. In Proceedings of New Orientations in Signal Processing . Liptovský Mikuláš: Military Academy, 3-6. (in Czech) Ďaďo, S., Šmíd, R. (2003). Wavelet correlation for biomedical shape evaluation. In Measurement 2003

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Design and Optimization of Levenberg-Marquardt based Neural Network Classifier for EMG Signals to Identify Hand Motions

This paper presents an application of artificial neural network for the classification of single channel EMG signal in the context of hand motion detection. Seven statistical input features that are extracted from the preprocessed single channel EMG signals recorded for four predefined hand motions have been used for neural network classifier. Different structures of neural network, based on the number of hidden neurons and two prominent training algorithms, have been considered in the research to find out their applicability for EMG signal classification. The classification performances are analyzed for different architectures of neural network by considering the number of input features, number of hidden neurons, learning algorithms, correlation between network outputs and targets, and mean square error. Between the Levenberg-Marquardt and scaled conjugate gradient learning algorithms, the aforesaid algorithm shows better classification performance. The outcomes of the research show that the optimal design of Levenberg-Marquardt based neural network classifier can perform well with an average classification success rate of 88.4%. A comparison of results has also been presented to validate the effectiveness of the designed neural network classifier to discriminate EMG signals.

Open access
Phased Array Receiving Coils for Low Field Lungs MRI: Design and Optimization

Phased Array Receiving Coils for Low Field Lungs MRI: Design and Optimization

Recent techniques of radiofrequency (RF) probes and preamplifiers in Magnetic Resonance Imaging (MRI) developments almost reached the physical limits of signal to noise ratio (SNR). More improvements in speed accelerations of data acquisition are very difficult to achieve. One exception, called RF phased array coils, is recently being developed very progressively. The approach is conceptually similar to phased array used in radar techniques; hence it is usually called MRI phased array coils. It is necessary to ensure independence of the individual coil channels in the array by the coil and preamp decoupling and the coil geometry optimization to get maximum benefits from this technique. Thus, the qualitative design and method for optimization of geometric properties of the coil elements in phased arrays, with aim to increase SNR, minimize the G-factor and to limit noise correlation, are proposed in this paper. By the finite element method (FEM) simulations, we obtained the sensitivity maps and inductances of the coils. The introduced program primarily calculates the Sensitivity Encoding (SENSE) G-factor along with other parameters that can be derived from sensitivity maps. By the proposed optimization algorithm, the program is capable to calculate the optimal values of the geometric coil parameters in a relatively small number of iterations.

Open access
Hybrid Effects of Stirrup Ratio and Steel Fibers on Shear Behaviour of Self-Compacting Concrete

Abstract

Shear cracking behaviour of fibrous self-compacting concrete of normal and high strength grade (M30 and M70) is presented here. Two stirrup diameters (6mm ∅ and 8 mm ∅) with a constant steel fiber content of 38 kg/m3 (0.5% by volume of concrete) were selected for the present study. The size of the beam was fixed at 100x200x1200mm. The clear span of the beam 1100mm, was maintained throughout the study. A total of 16 shear-deficient beams were tested under three point loading. Two stirrup spacing (180mm and 360 mm) are used for the shear span-to-depth ratio (a/d = 2). Investigation indicates that initial cracking load and ultimate load increased as the area of shear reinforcement increased by increasing the diameter of stirrup. It was also noted that the failure mode was modified from brittle shear failure to flexural-shear failure in the presence of fibers. The mechanical behaviour of SFRSCC was improved due to the combined effect of stirrups and steel fibers. The stiffness, toughness, and deflection of the beams increased when compared to SCC beams without fibers. The experimental results were compared with existing models available in literature, and the correlation is satisfactory.

Open access