Achievement of AC Voltage Traceability and Uncertainty of NIS, Egypt through Capabilities of NIST, USA

This paper describes the methodology used to achieve the AC voltage traceability and the associated uncertainty in National Institute for Standards (NIS), Egypt via the capabilities of National Institute for Standards and Technology (NIST), USA.  The methodology includes the use of the thermal voltage converters (TVCs) and micropotentiometers (µPots) via a new automated calibration system for determination of the AC-DC Differences at different frequencies.  To confirm the results of this process, a bilateral comparison with NIST was organized through a set of (TVCs) to cover the range from 1 V to 200 V at frequencies of 55 Hz, 1 kHz, 10 kHz and 200 kHz.  The comparison results associated with the uncertainty analysis are also discussed in this paper.  For low values of AC voltage, new three µPots were fabricated at NIST to establish the traceability from 50 mV to 200 mV at frequencies from 20 Hz to 1 MHz. The converters used in this work are also modeled then simulated using LT-spice/SwCAD III simulator. Keywords: electrical measurements, thermal voltage converter, micropotentiometer, modelling and electrical simulation, uncertainty analysis, bilateral comparison

Kinetic Studies on Thermal Degradation of Nonwood Plants

Thermal analysis of nonwood plants (bagasse, rice straw, and rice hulls) was carried by using differential thermal (DT) and thermogravimetric (TG) analysis under oxidizing and inert atmospheres. Degradation patterns were different, depending on the kind of material and on the pyrolytic atmosphere. Thermal curves of rice straw and hulls were very similar, but bagasse showed a different curve. Degradation of bagasse is similar to hardwood. The rate of thermal degradation of nonwood plants is faster than wood because of their porous structure. Kinetic studies were based on weight loss obtained from TG analysis. A dual mechanism concept, similar to wood, was found for nonwood plants. Two values of activation energy were obtained with a transition temperature at 335 C. Rice straw and hulls have low values of activation energy due to their porous structure and presence of high percentage of silica, while activation energies of bagasse are close to that of hardwood. The presence of inorganic impurities in the cellulosic material has an effect on the kinetics of thermal decomposition

Studies on the Mechanism of Flame Retardation in Wood

Two lignins, of different carbohydrate content, were pyrolyzed before and after treatment with inorganic salts. Lignin that is relatively free of carbohydrate was inert to the salts: its DTA curve did not change. The DTA curve of lignin associated with about 50% carbohydrate showed a shift of the exothermic peak io a higher temperature and the appearance ofa new exotherm; lithium chloride was the most effective salt in causing this shift. The results support the chemical theory of flame retardation

Mechanism of Thermal Decomposition of Lignin

Differential thermal analysis studies of milled wood lignin and lignin carbohydrate complex at different heating rates showed three exothermic peaks. The heating rate is the factor that affects their sharpness and position. The peaks are sharp at low heating rates. Infrared spectra and scanning electron micrographs of the pyrolyzed lignin residues show that aliphatic scission of the lignin molecule at the onset of pyrolysis and progressive carbonization of the surface are the principal features of degradation; there is no intermediate compound formed during the pyrolysis

Theoretical Study of Variation of Propagation Constant in a Cylindrical Waveguide Due to Chirality: Chiro-Phase Shifting

We discuss a conceptual idea for a reciprocal phase shifting using chiral materials. Such phase shifters, which can be called chiro-phase shifers, may, in principle, consist of a general cylindrical waveguide in which a thin chiral rod is inserted longitudinally. A standard commonly used perturbation technique is utilized to analyze theoretically the effects of a chiral rod\u27s parameters (and in particular its chirality admittance) on propagation constants of guided modes in such waveguides. A simple expression relating the relative change of propagation constants to other relevant quantities such as polarization characteristics of unperturbed guided modes, material parameters of chiral rod, and location of the rod is presented, and the case of a circular metallic chiro-phase shifter is discussed in some detail. Physical insights into the results are also provided

Surface and subsurface structures of Kalabsha area, southern Egypt, from remote sensing, aeromagnetic and gravity data

AbstractKalabsha area is known to be the most seismo-active zone at the southwestern region of the Aswan High Dam, in southern Egypt. The main purpose of this work is the analysis and interpretation of satellite imagery, aeromagnetic and ground gravity data of Kalabsha area in order to reveal the subsurface lithology and structure. The Landsat ETM+ data were produced in a false-color composite image (bands 1, 2 and 3 in RGB) at the same scale as the geological map in order to reveal some extra geological and structural features.An attempt has been made to analyse the complex nature of gravity and magnetic anomalies over the Kalabsha area to reveal their relationship with surface geology, structure and tectonics setting. These analyses include isolation of anomalies into regional and residual components using the band-pass filter, second vertical derivatives (SVD), upward continuation, and shadowgrams technique. It was noticed that, there is close correlation between gravity, magnetic and many of the major surface geological features of the region. The basement structural map of Kalabsha area has been prepared from the integration of SVD of regional component maps of both gravity and magnetic.The interpretation of the basement tectonic map of the area indicated the presence of two sets of faults NNW–SSE to N–S which is dissected by an E–W to WNW–ESE fault system. These two sets of fault systems as deduced from the gravity and aeromagnetic data were found to match well with that obtained from the Landsat image and geological map

Polarographic Studies on Complexes of Pd(II) & Co(II) with Triethanolamine

721-72

Evaluating Water Table Rising Under Eastern Cairo (Metro Line)

The booming increase in population in last decades led to poor environmental condition in some areas in the capital city of Egypt. The main two tackled environmental impacts from the increased population, in this research, are the heavy traffic densities jam and groundwater rise in many areas in the city. The massive population causes traffic congestion in the capital due to the increased poor planned urban expansion. The groundwater rise is resulted from leakage from over loeaded and poorly maintained drinking and sanitary water networks. More than 40% of the capacity of these networks leaked to ground, moving, with the topographic gradient sub-surfable  to the lower areas; transporting all pollutants and dissolved salts from soil to the aquifer. This, also, threatens the buildings stability and prevent the usability of these buildings. The government is currently exerting massive efforts and increasing the investments tremendously on solving the traffic congestions and implementing new roads. Zooming into the study area, replacing the non-working old metro track into a road to link between Mansheyet El-Bakry and El-Demrdash is faced with the high groundwater table occurring in the area. The main objective of the current research is, to evaluate the proposed alternatives for solving the traffic problem through implementing new road, taking into consideration conducting a suitable solution for the high groundwater table. Moreover, investigating the main causes of the groundwater rise and assess environmentally the impact on the study area. Several proposed alternatives were evaluated for solving the concerned issues through extensive field and hydrogeological investigations, pumping tests, and numerical model (GMS- modflow) to simulate the hydrogeological conditions of the study area and test the proposed solutions. The alternatives were, also, assessed through a designed weighted impact assessment to analyze the best solution. the weighting assessment factors include efficiency, initial and operational costs, extracted water volume, lower groundwater rise, building stability, construction feasibility. The comprehensive investigation and assessment indicated that the most effective solution.  Nevertheless, prevention at source is also urgently needed through rehabilitation of drinking and sanitary water networks in the capital to minimize the seepage and losses percentage of the transported water. Keywords:Groundwater Rise, Cairo, traffic congestions, dewatering system, groundwater modeling, groundwater quality DOI: 10.7176/CER/14-6-03 Publication date:October 31st 2022

Sentiment Analysis on Twitters Big Data Against the Covid- 19 Pandemic Using Machine Learning Algorithms

This paper analyzes users reactions on Twitter to the COVID-19 pandemic, using machine learning and data mining algorithms to classify tweets according to economic and health fears. A large dataset of tweets is explored, extracted, transformed, loaded, cleansed, and analyzed. The proposed framework improves prediction quality with a proposed dictionary that is used to classify tweets. The study compares four supervised machine learning algorithms and finds that people discuss the pandemics dangers from economic and health perspectives with equal frequency. The Naive Bayes algorithm achieves the highest percentage of correct predictions