Estimation of Concrete's Porosity by Ultrasounds

AbstractDurability of concrete depends strongly on porosity; this conditions the intensity of the interactions of the concrete with the aggressive agents. The pores inside the concrete facilitate the process of damage, which is generally initiated on the surface. The most used measurement is undoubtedly the measurement of porosity accessible to water. The porosimetry by intrusion with mercury constitutes a tool for investigation of the mesoporosity. The relationship between concrete mixtures, porosity and ultrasonic velocity of concrete samples measured by ultrasonic NDT is investigated. This experimental study is interested in the relations between the ultrasonic velocity measured by transducers of 7.5mm and 49.5mm diameter and with 54kHz frequency. Concrete specimens (160mm diameter and 320mm height) are fabricated with concrete of seven different mixtures (various W/C and S/S+G ratios), which gave porosities varying between 7% and 16%. Ultrasonic velocities in concrete were measured in longitudinal direction. Finally the results showed the influence of ratio W/C, where the porosity of the concretes of a ratio W/C _0,5 have correctly estimated by ultrasonic velocity. The integration of the concretes of a lower ratio, in this relation, caused a great dispersion. Porosity estimation of concretes with a ratio W/C lower than 0,5 became specific to each ratio

Nanostructured Al doped Sn02 films grown onto ITO substrate via spray pyrolysis route

We report on nanostructured films of Al doped tin oxide grown by facile spray pyrolysis route, and their physical properties are investigated. The sprayed films are grown onto ITO substrate at 300°C from (SnCl4, 5H2O)as precursor. The content of Al is kept at 3 % in the solution. Structural, optical, electrical and surface properties are investigated. X-rays pattern reveals polycrystalline structure and SnO2 phase occurence. The visible transmitance exceeds 85%, the band gap is 3.7 eV.Nanotips are observed by 3D atomic force microscope (AFM) picture. The films exhibits very low resistivity found to be 9.85 10-5.cm, a high electron concentration around 1021cm-3, and low mobility 20 cm2/Vs. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2053

Effect of metal on characteristics of MPc organic diodes

The fabrication and electrical characterization of metal phthalocyanine MPc organic diodes have been investigated. The Au / MPc / Si Schottky diodes are fabricated via a spin coating route. Based on the electrical measurement of the current versus bias voltage in dark conditions we extract the parameters such as ideality factor, saturation current, series resistance and rectifying factor. Role of metal M = Cu, Al, Zn, Mg on the electronic parameters is emphasized. The obtained values of n, 1.85, 2.22 and 4.40, show a non-ideal behavior. Using a derivate dV / dlnI and H(I) functions, we determine the ideality factor and series resistance and found to be 2 and 17 Ω for the CuPc device

RETRACTED : Influence parameters analysis in the gear helix correction

This article has been retracted at the request of the Editors-in-Chief, according to the Publication Ethics Policy and Publication Malpractice Statement.Please see : http://revue.ummto.dz/index.php/JMES/about/editorialPolicies#custom-2 This note is published, 25 June 202

Nanostructured Al Doped SnO2 Films Grown onto ITO Substrate via Spray Pyrolysis Route

We report on nanostructured films of Al doped tin oxide grown by facile spray pyrolysis route, and their physical properties were investigated. The sprayed films were grown onto indium tin oxide (ITO) substrate at 300 °C from the precursor (SnCl4, 5H2O). The content of Al is kept at 3 % in the solution. Structural, optical, electrical and surface properties were investigated. X-rays pattern reveals polycrystalline structure and SnO2 phase occurence. The visible transmitance exceeds 85 %, the band gap is found to be 3.7 eV. Nanotips were observed by 3D atomic force microscope (AFM) observation. Using the Hall effect measurements system (HMS), the films exhibit very low resistivity found to be 9.85 10 – 5 Ω.cm, a high electron concentration is around 1021 cm – 3, and the mobility reaches the value of 20 cm2/Vs. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2490

Evaluation of dimensionality reduction using PCA on EMG-based signal pattern classification

In this paper, we present a new low-cost system for surface electromyogram (sEMG) acquisition. developed and designed for rehabilitation application purposes. The noninvasive device delivers four-channel EMG bio-signals describing the electrical activity for the right upper limb muscles. The recorded EMG signals obtained from several healthy subjects were exploited to build a database for movement detection and to evaluate the mechanical properties of the upper limb muscles. The proposed study focuses mainly on the influence of the use of the principal component analysis (PCA) method on the movement classification performance based on the sEMG extracted signals. Several tests were conducted, and the simulation results clearly showed the positive impact of PCA as a dimensionality reduction approach with respect to two performance metrics: the classification rate (CR) and the system’s response time. This advantage was confirmed via numerical tests using three different classifiers: K-nearest neighbor (KNN), probabilistic neural network (PNN), and learning vector quantization (LVQ), with and without PCA. The obtained classification rates highlighted the success of the proposed method since a clear improvement in the classification rates was achieved

RETRACTED : Influence parameters analysis in the gear helix correction

This article has been retracted at the request of the Editors-in-Chief, according to the Publication Ethics Policy and Publication Malpractice Statement.Please see : http://revue.ummto.dz/index.php/JMES/about/editorialPolicies#custom-2 This note is published, 25 June 202

Multimodal biometric system for ECG, ear and iris recognition based on local descriptors

© 2019, Springer Science+Business Media, LLC, part of Springer Nature. Combination of multiple information extracted from different biometric modalities in multimodal biometric recognition system aims to solve the different drawbacks encountered in a unimodal biometric system. Fusion of many biometrics has proposed such as face, fingerprint, iris…etc. Recently, electrocardiograms (ECG) have been used as a new biometric technology in unimodal and multimodal biometric recognition system. ECG provides inherent the characteristic of liveness of a person, making it hard to spoof compared to other biometric techniques. Ear biometrics present a rich and stable source of information over an acceptable period of human life. Iris biometrics have been embedded with different biometric modalities such as fingerprint, face and palm print, because of their higher accuracy and reliability. In this paper, a new multimodal biometric system based ECG-ear-iris biometrics at feature level is proposed. Preprocessing techniques including normalization and segmentation are applied to ECG, ear and iris biometrics. Then, Local texture descriptors, namely 1D-LBP (One D-Local Binary Patterns), Shifted-1D-LBP and 1D-MR-LBP (Multi-Resolution) are used to extract the important features from the ECG signal and convert the ear and iris images to a 1D signals. KNN and RBF are used for matching to classify an unknown user into the genuine or impostor. The developed system is validated using the benchmark ID-ECG and USTB1, USTB2 and AMI ear and CASIA v1 iris databases. The experimental results demonstrate that the proposed approach outperforms unimodal biometric system. A Correct Recognition Rate (CRR) of 100% is achieved with an Equal Error Rate (EER) of 0.5%