Engineering, Technology and Applied Science Research

Published by Engineering, Technology and Applied Science Research
Online ISSN: 1792-8036
Publications
Article
This paper compares the prestress losses as calculated by four different design codes; British standard CP110, Comite Europeen du Beton 70 and 78, American Concrete Institute 77 and the Prestressed Concrete Institute method (PCI). The comparison is done by determining the total losses which take place in a rectangular prestressed concrete beam for both pre-tensioning and post-tensioning systems. The results show that total losses calculated for the post-tensioning method are higher than those calculated for the pre-tensioning method, which is not the usual case. It seems that the PCI method may be required for special structures or for simply supported slender members which may be sensitive to small changes in deflections. However, for non-special structures, or where actual losses have little effect on the design, it is better to compute losses by the ACI method because it is simple and does take into considerations interactions between the various sources of losses. However, it is not possible to conclude which method gives the more accurate prediction of shrinkage and creep without direct co-relation to realistic insitu data.
 
Corrosion rates of samples that were corroded for 168 hours in 3.5% NaCl
SEM investigations after the corrosion test, (a) 4.7m/min, (b) 10m/min
Article
In this study, the effect of Shot Peening (SP) and Micro Arc Oxidation (MAO) process on the corrosion resistance of 0.5% La with added AZ31 Mg alloy, hot rolled at different rolling speeds, was investigated. It was found that the surface of the rolled material at a rolling speed of 4.7m/min had higher surface smoothness values than the one rolled at 10m/min. It was observed that the corrosion rate changed in the first 40 of 168 hours. In the following hours, the corrosion rate showed different results according to the initial microstructure properties of the base materials. Initially, pore size was the dominant factor determining corrosion resistance, although, after coating, the corrosion rate was affected by the twins formed, based on rolling speed, which enhanced the corrosion rate between 48 and 168 hours.
 
Article
The growth mode of MgCl2 on Ti (0001) and on SiO2 grown on Si (100) was investigated by X-ray Photoelectron Spectroscopy (XPS) under UHV conditions. Magnesium chloride grows on both Ti (0001) single crystal and SiO2 following the Frank-van der Merve, (FM) growth mode.
 
Article
In order to meet the socio-economic demands around the globe, construction industry not only consumes concrete at a very fast pace but also yields huge amounts of construction and demolishing waste. The phenomenon gives rise to environmental issues due to production of concrete ingredients and due to dumping of the waste. Therefore, one of the solutions is the production of green concrete utilizing demolished waste. This research work studies the effect of prolonged fire (18 hours) on the flexural behavior of reinforced concrete–recycled aggregate beams. The beams were using 50% replacement of natural coarse aggregates with demolished concrete. The beam samples were cast as both normal and rich mix concrete and were cured for 28 days. After curing, the beams were exposed to fire at 1000°C in a purpose made oven, followed by testing in a universal load testing machine under central point load. The test results show that the proposed beams (cast with rich mix) exhibited about 22% reduction in flexural strength. The failure mode of the beams was observed as shear failure.
 
Article
Libya is currently interested in utilizing renewable energy technologies to reduce the energy dependence on oil reserves and Greenhouse Gas (GHG) emissions. The objective of this study is to investigate the feasibility of a 10MW grid-connected PV power plant in Libya. NASA data are used to analyze the global horizontal irradiation, direct normal irradiation, and air temperature of 22 selected locations in Libya and to evaluate the potential of solar energy. RETScreen software is used to estimate the energy production, GHG emissions, and financial parameters for the 22 locations. Based on the solar atlas map, it is noticed that the highest global horizontal irradiation is in the southern part of Libya, which ranged from 2100 to 2500kWh/m2. These results indicate that Libya has a huge solar energy potential that can be used to ‎generate electricity. Moreover, based on techno-economic results, it is observed that the highest electricity generation of 22067.13MWh is recorded at Al Κufrah and the lowest at Al Jabal al Akhdar with a value of 17891.38MWh. Furthermore, Al Kufrah and Murzuq are the best locations for the future installation of PV power plants from annual energy and the economic parameters point of view. The maximum value of power that can be generated by the plant was estimated to be 22.06GW.
 
(a) shows the ratio of the intensity of Cl2p photoelectron peak of the deposit, divided with the intensity of the Si2p of the substrate as a function of the deposition time of each step. In this case there are no obvious changes in the slope of the line, indicating that there is no layer by layer growth of the deposit. Although, fig.4 (b) shows an almost exponential increase of MgKLL intensity as a function of deposition time which is characteristic of layer by layer growth of the deposit through the law of Beer. This observation could be explained by taking into account that the reconstructed Si (111)7x7 surface is a very rough surface
Graphical representations of the ratios Cl2p/Si2p and MgKLL/Si2p as a function of the MgCl2 deposition time.
Article
The growth mode of MgCl2 on Au foil and Si (111) 7x7 reconstructed surface under UHV conditions, was investigated by X-ray Photoelectron Spectroscopy (XPS). Magnesium chloride grows with the Frank-van der Merve, (FM) growth mode on the Au foil. On Si surface there is evidence for the layer by layer growth of MgCl2 but leaving uncovered silicon areas at the first steps of deposition due to the Si (111)7x7 surface roughness.
 
Comparison of primary and secondary inductance for the different topologies of the on-chip TF, for the case of flipped (dash line) and nonflipped (solid line) feed lines. (a) Octagon interleaved TF (b) Octagon stacked TF (c) Square interleaved TF (d) Symmetrical square and octagon interleaved TF
Figure 6: Comparison values of (a) Minimum insertion loss, and (b) Coupling factor K for different topologies of the on-chip TF
Article
In this study, modeling and designing different topologies of on-chip transformers are presented using 130nm SiGe BiCMOS technology. Interleaved, stacked, and full symmetrical interleaved transformers are investigated. Octagon and square shapes are used for designing transformers with flipped and non-flipped feed lines. A comparison between performances of various configurations is presented using a full-wave simulator. The octagon stacked transformer with flipped feed lines showed a good performance at around 60GHz. The simulated results demonstrated a coupling factor K of 0.94, minimum insertion loss of 1.01518dB, and Q-factor of 9 with a minimum occupied area of 0.0019mm2.
 
Article
In chaos-based spread spectrum systems, the use of spreading code and chaotic binary sequence expands the bandwidth of the information-bearing signal but this expansion results in SNR degradation under the constraint of constant channel capacity according to Hartley-Shannon law. To compensate for this drawback, our proposed model employs an irregular low-density parity-check (LDPC) code with its iterative decoding algorithm. Coupled with this forward error correction (FEC) coding, we used non-coherent (NC) 16-ary differential chaos shift keying (16-DCSK) that additionally provides the ability of data encryption due to its use of chaotic signals compared with the conventional modulation schemes. Analytical expressions of bit error probability (BEP) are derived under the assumption of the three-ray model along with partial band noise jamming (PBNJ) over a Rayleigh fading channel. Simulation results assert that the proposed system can mitigate the effect of PBNJ via lowering BEP by coding gain and processing gain under identical transmission power. It is also confirmed that a higher level of security can be provided by the use of proposed two iteration functions of Duffing Map-based chaotic binary sequence than the security level of one iteration function of Logistic Map, based on the balance and autocorrelation analysis.
 
Confirmed COVID-19 cases per million. Published online at OurWorldInData.org. Retrieved from: https://ourworldindata.org/coronavirustesting [3].
Confirmed COVID-19 deaths per million. Published online at OurWorldInData.org. Retrieved from: https://ourworldindata.org/coronavirustesting [3].
Article
The importance of classification algorithms has increased in recent years. Classification is a branch of supervised learning with the goal of predicting class labels categorical of new cases. Additionally, with Coronavirus (COVID-19) propagation since 2019, the world still faces a great challenge in defeating COVID-19 even with modern methods and technologies. This paper gives an overview of classification algorithms to provide the readers with an understanding of the concept of the state-of-the-art classification algorithms and their applications used in the COVID-19 diagnosis and detection. It also describes some of the research published on classification algorithms, the existing gaps in the research, and future research directions. This article encourages both academics and machine learning learners to further strengthen the basis of classification methods.
 
Visualization of a few ovid CXR images.
CT scan images of covid patients.
CT scan images of normal patients.
General architecture of the CovNet.
Article
Covid-19 is a highly infectious disease that spreads extremely fast and is transmitted through indirect or direct contact. The scientists have categorized the Covid-19 cases into five different types: severe, critical, asymptomatic, moderate, and mild. Up to May 2021 more than 133.2 million peoples have been infected and almost 2.9 million people have lost their lives from Covid-19. To diagnose Covid-19, practitioners use RT-PCR tests that suffer from many False Positive (FP) and False Negative (FN) results while they take a long time. One solution to this is the conduction of a greater number of tests simultaneously to improve the True Positive (TP) ratio. However, CT-scan and X-ray images can also be used for early detection of Covid-19 related pneumonia. By the use of modern deep learning techniques, accuracy of more than 95% can be achieved. We used eight CNN (CovNet)-based deep learning models, namely ResNet 152 v2, InceptionResNet v2, Xception, Inception v3, ResNet 50, NASNetLarge, DenseNet 201, and VGG 16 for both X-rays and CT-scans to diagnose pneumonia. The achieved comparative results show that the proposed models are able to differentiate the Covid-19 positive cases.
 
ML solutions towards the Covid-19 pandemic.
Article
Coronavirus-2019 disease (Covid-19) is a contagious respiratory disease that emerged in late 2019 and has been recognized by the World Health Organization (WHO) as a global pandemic in early 2020. Since then, researchers have been exploring various strategies and techniques to fight against this outbreak. The point when the pandemic appeared was also a period in which Machine Learning (ML) and Deep Learning (DL) algorithms were competing with traditional technologies, leading to significant findings in diverse domains. Consequently, many researchers employed ML/DL to speed up Covid-19 detection, prevention, and treatment. This paper reviews the state-of-the-art ML/DL tools used, thoroughly evaluating these techniques and their impact on the battle against Covid-19. This article aims to provide valuable insight to the researchers to assess the use of ML against the Covid-19 pandemic.
 
Article
The adoption of e-learning technology has become a major challenge for many academic institutions during the Covid-19 pandemic. More and more institutions are questioning the success of adopting this technology and are seeking to understand their adoption process. The objective of the current research work is to study the factors affecting the intent of Saudi university students to adopt online technologies during the Covid-19 pandemic. Based on the Information Technology Adoption Model, UTAUT, a research model was designed and validated by combining the factorial analysis method with simple linear regression analysis. The study revealed four key factors that had significant and positive effects on users' intent to use online technology, including the perceived usefulness, perceived ease of use, teacher influence, university management commitment, and availability of student technical assistance.
 
Article
The current paper aims to analyze the architectural genotype principle that considers the arrangement of spaces as an abstract relational model. The goal is to demonstrate that syntactic measurements show that spatial structures allow messages to be decoded in each dwelling's inner spaces' architecture. The research uses the justified graphic technique for spatial syntax. Twelve detached houses have been randomly selected out of a total of sixty-two contemporary buildings that were built in a subdivision of Setif between 1990 and 2010. The analysis findings showed that the spatial characteristics and properties that constitute the generic rule underlying the studied space can be detected. This research supports the notion that the implementation of the spatial syntax method can aid in the proposition of innovative solutions regarding the design of sustainable housing projects.
 
Article
This paper aims to apply the Fourth Order Finite Difference Method (FDM) to solve the one-dimensional unsteady conduction-convection equation with energy generation (or sink) in cylindrical and spherical coordinates. Two applications were compared through exact solutions to demonstrate the accuracy of the proposed formulation.
 
Article
In the domain of image captioning, many pre-trained datasets are available. Using these datasets, models can be trained to automatically generate image descriptions regarding the contents of an image. Researchers usually do not spend much time in creating and training the new dataset before using it for a specific application, instead, they simply use existing pre-trained datasets. MS COCO, ImageNet, Flicker, and Pascal VOC, are well-known datasets that are widely used in the task of generating image captions. In most available image captioning datasets, image textual information, which can play a vital role in generating more precise image descriptions, is missing. This paper presents the process of creating a new dataset that consists of images along with text and captions. Images of the nearby vicinity of the campus of MIT World Peace University-MITWPU, India, were taken for the new dataset named MITWPU-1K. This dataset can be used in object detection and caption generation of images. The objective of this paper is to highlight the steps required for creating a new dataset. This necessitated a review of the existing dataset models prior to creating the new dataset. A sequential convolutional model for detecting objects on a new dataset is also presented. The process of creating a new image captioning dataset and the gained insights are described.
 
Map of the two nested domains of WRF simulations at the Kabul River Basin (d01 = 6km, d02 = 2km).
Time series comparison between the WRF simulated precipitation (blue), observed gauge precipitation (red), and TRMM precipitation (green) for d01 (left column) and d02 (right column).
WRF precipitation percent bias against gauge data in domain d01 and domain d02.
Article
Extreme precipitation events are among the most severe weather hazards. Knowledge about the spatial patterns underlying such events in the Upper Indus Basin is limited because estimating precipitation is very challenging due to the data scarcity and the complex orography. Numerical weather prediction models can be applied at a fine resolution to overcome this issue. The Advanced Research Weather Research and Forecasting (WRF) model version 3.8.1 was applied over the Kabul River Basin to simulate the temperature and precipitation of monsoon season 2010, i.e., 1st May to 16th September 2010. We considered the May month as a spin-up period. The initial and boundary conditions were derived from the National Oceanic and Atmospheric Administration, Climate Forecast System Reanalysis data. The model was set up by using two-nested domains with increasing horizontal resolution moving inward from 15km on domain d01 to 5km on domain d02. The simulations were compared with TRMM 3B42, and station data collected from the Pakistan Meteorological Department and Water and the Power Development Authority using bias, percentage bias, root mean square error, and Pearson correlation. The results revealed that the simulated precipitation was improved from d01 to d02. However, the model showed mixed results with overestimation of precipitation at some stations and underestimations at others. Simulated precipitation generally agreed better with TRMM than with station data. Overall, the results indicate that the WRF model can be used to simulate heavy precipitation in complex terrain.
 
Respondents' academic qualification.
Significant factors hindering the implementation of ISO (with AI score).
Article
ISO 9001:2015 is known as the highest quality management standard, enhancing customer and company satisfaction. While the manufacturing industry is playing a vital role in Pakistan’s GDP, the implementation of ISO 9001:2015 is not widespread. This study aims to examine the factors that hinder the implementation of ISO 9001:2015 in Pakistan’s manufacturing industry and recommend suggestions to overcome them. An in-depth literature review identified 32 general factors that hinder the implementation of ISO 9001:2015. A structured questionnaire was designed and distributed to 135 respondents to examine the factors hindering the implementation of ISO 9001:2015 in Pakistan’s manufacturing industry. The gathered data were analyzed using the average index formula, and 8 significant factors were identified. These factors were used in the design of a semi-structured questionnaire distributed among high qualified and experienced respondents working in top managerial posts of manufacturing industries in Pakistan. The collected data were analyzed using content analysis. The findings can be helpful in the determination of recommendations regarding the implementation of ISO 9001:2015 in the manufacturing industries of Pakistan.
 
Article
The Greek islands of Crete and Rhodes are equipped with isolated transmission systems that fall under the jurisdiction of the Islands Network Operation Department of HEDNO S. A., which carries out their operation and maintenance on behalf of PPC S.A. After 2016, the Transmission Line Operation and Maintenance Subsection of the Department, started to incorporate new approaches to improve the routine work of the subsection. These approaches include Unmanned Aerial Vehicle (drone) inspections, GIS/GPS software/applications and project management/issue tracking tools such as Mantis Bug Tracker (or MantisBT. This paper provides a brief review of the maintenance practices in combination with the properties and peculiarities of the specific systems, and further investigates the MantisBT records from 2016 to 2020, in order to provide a view of the routine work of transmission line maintenance through the case studies of Crete and Rhodes. It should be noted that the majority of these issues are related to the Cretan transmission system and thus, this paper also aims to provide a screenshot of the situation before the interconnection of the isolated Cretan Transmission System to the mainland system, expected to initiate in 2021.
 
Article
Colombo district has become an increasingly congested urban society. It has been reported that the frequent flooding in the Colombo district occurs due to the shrinking of open spaces, illegal constructions, and lack of suitable waste disposal facilities. Therefore, this study focuses on analyzing the impact of land-use change on the flood of Colombo district in May 2016 in comparison to the land-use during the flood in 1989. Accordingly, Landsat images were utilized to identify the land-use by using NDVI, NDBI, and NDWI indices. Out of the several techniques examined, SVM classification was chosen, and change detection techniques in conjunction with remote sensing and GIS environment were adopted. SVM classification showed the highest accuracy for land-use classification, which was 99.0% in 1989 and 99.9% in 2016. The comparison of land-use changes of 1989 and 2016 with similar flood extent of the Colombo district proved that the area of the Kelani river watershed changed into urban area, having a significant impact on flood inundation. The Kelani river watershed includes 23% of the total urban area of the Colombo district. Similarly, the entire area of land-use transformation covered 37.7% of the area within the watershed region of the Colombo district. Eventually, this research identified the significant impact of Colombo district floods in May 2016 on land-use changes.
 
Article
This paper presents the results of a foresight study examining the future knowledge, skills, and competencies required by quality professionals to meet the goals and objectives of the Saudi Vision 2030. The study aims to develop a methodology allowing the forecasting of skills and competency demands in the future. Data collection was conducted through the design of a web-based questionnaire that was distributed online to academic and quality management specialists in Saudi Arabia. The questionnaire consisted of four sections and forty items aiming to identify the necessary competencies that quality professionals should develop to deal with the changing business environments. The validity and reliability of the questionnaire were confirmed by Cronbach’s alpha and the data were analyzed using descriptive tests (mean and standard deviation). One-way ANOVA method was also used to test the significant differences in participants’ attitudes. The results of the study clearly emphasize on the emerging need for new effective skills to face this new era of the rapid pace of technological changes. The outcomes of this study may be used by policy-makers, local authorities, employers, academics, and researchers to set up future-oriented education and training policies to bridge the gap between skills demand and supply which arises out of labor market changes.
 
Article
This paper presents the traveling wave based fault location methods of SEL-400L, and SFL-2000 available on the market for a 66.9km, 220kV Hoa Khanh-Thanh My transmission line in Central Viet Nam, such as single-ended, and double-ended, all of which rely on measurements from inductive CTs and capacitive VTs. Focus was given on the building process of a Matlab Simulink model to evaluate these methods. Current and voltage signals were sent to an analog Chebyshev type II filter which passes higher frequency signals at 3kHz and rejects low frequencies signal at 50Hz. After that, these output signals are used in Clarke's transformation for getting 0 and α components. The detail coefficient of the selected components after DWT using Db4 wavelet at decomposition level 1 can be used to determine the fault types, the direction of fault and propose a crest-wave comparison solution to identify exactly the adjacent bus' reflected wave from the fault point's reflected wave for the fault location. Finally, the accuracy of fault location on the transmission line is reviewed by varying various parameters like fault type, fault location and fault resistance on a given power system model.
 
Gradation of RA and NA
Maximum load
Maximum deflection
Average flexural strength (rich mix vs normal mix)
Article
In this article, the effect of prolonged fire (24-hour duration) on reinforced concrete beams made with recycled aggregates from demolished concrete was experimentally investigated. Demolished concrete was used recycled coarse aggregates in equal proportion with natural coarse aggregates. Normal and rich mix concrete with water-cement ratio equal to 0.54 were used. As a control specimen, beams with all-natural aggregates were also cast to compare with the results of the proposed beams. All beams were cured for 28 days and exposed to fire at 1000°C in an oven for 24 hours. After the elapse of this fire period, the beams were allowed to air cool, followed by testing till failure in a universal load testing machine. Comparison of the test results shows that rich mix concrete beams more reduction in flexural strength, more increase in maximum load carrying capacity and deflection than normal mix beams. The maximum reduction in flexural strength was 32.41% for beams cast with 50% RCA and rich mix. Although the fire duration used in this study is rare, yet the outcome provides guidelines for taking proper decisions for retrofitting/strengthening of the fire affected structure before putting it back in service.
 
Geometrical representation of the slotted patch element of the proposed microstrip antenna.
S11 parameter as a function of frequency for the proposed antenna design.
The radiation pattern and E-H plane for the proposed antenna at 28GHz.
Article
Microstrip patch antennas have been widely investigated and used in modern mobile communication technologies including 5G. Previous works in the area demonstrated that such antennas can be designed to operate in the low, mid, and high bands of 5G networks. This paper focuses on high-band millimeter-wave 5G mobile applications. In particular, the proposed microstrip patch antenna was designed to operate at 26 and 28GHz, which are the first introduced and widely used frequency bands of the 5G. This study aims to enhance the gain and other radiation characteristics of the antenna by adding a combination of different slot shapes to a single rectangular patch that is commonly used in other 5G antennas. The results show that an extremely high gain is achieved by inserting two symmetric L-slots and a middle-placed square slot. The dimensions of the slots were simulated and optimized using the CST Studio Suite simulator. A comparative study was also conducted showing that the proposed antenna features higher gain and directivity and provides very good VSWR and efficiency along with a reasonably large enough bandwidth at the two resonance frequencies considered.
 
Article
According to most valid Design Codes including the Iranian Seismic Design Code (Standard No. 2800), moment resisting frames in dual systems must have the ability of resisting the 25% of the total lateral load of the dual system independently. This study is conducted to investigate the implementation of this rule for dual steel structures with two types of steel braced frame. Also, its effect on the strength of the structure and the distribution of lateral load between the frames and the bracing system is evaluated. In order to investigate the effect of that rule, structural models with 5, 10 and 15 floors are modeled. Nonlinear static analysis is employed and results are discussed. Following the Standard No. 2008 seems to increase the structure’s lateral resistance and decrease the number of elements entered into the inelastic behavior stage. In general, the structure has a more desirable inelastic behavior.
 
Article
In next-generation mobile networks, hundreds of diverse devices aim to be interconnected, posing huge challenges in capacity, coverage, efficiency, reliability, and connectivity. These and other challenges are addressed at Radio Frequency (RF) parts such as several radiating unit antennas, with very fine beamforming capabilities along with the requirements of high gains and minimized size. This work presents an 8×8 Aperture Coupled Microstrip Patch Antenna (AC-MPA) in the form of a planar array modeled for the 28GHz frequency band with high gain and compact size, making it suitable for 5G networks. The antenna is designed using a substrate with overall dimensions of 74.6×85.648×0.107mm3 and relative permittivity of ε0 = 4.3.
 
Article
This paper focuses on solving the fluid flow and heat transfer equations inside a two-dimensional square enclosure containing three hot obstacles affected by gravity and magnetic force placed on a ramp using Boltzmann method (LBM) applying multiple relaxation times (MRT). Although, the Lattice Boltzmann with MRT is a complex technique, it is a relatively new, stable, fast and high-accurate one. The main objective of this research was to numerically model the fluid flow and ultimately obtaining the velocity field, flow and temperature contour lines inside a two-dimensional enclosure. The results and their comparisons for different types of heat transfer revealed that free or forced heat transfer has a considerable impact on the heat transfer and stream lines. This can be controlled by modifying the Richardson number. It is revealed that changing the intensity of the magnetic field (Hartman number) has an appreciable effect on the heat transfer.
 
Article
Plane wave generator is normally composed of two explosives having dissimilar detonation velocity. It is used for directing the spherically outgoing shock wave front to a planar form. Plane wave generators are utilized to find material behavior under dynamic loading. This paper presents the shock arrival time for two plane wave generators by developed Matlab code and its comparison with Ansys Autodyn. The diameter of both plane wave generators is kept the same. One plane wave generator is composed of Octogen and Barium Nitrate and the other is composed of Octogen and Tri Nitro Toluene. Obtained results were surprisingly in agreement. Maximum and minimum obtained flatness for the plane wave were ±0.56 and ±0.08ms respectively within the whole diameter of the plane wave generator. The developed code can be utilized to find the profile of a plane wave generator, minimizing the time and cost many times.
 
Article
This paper researches a novel 2D Z-shaped Electromagnetic Band-Gap (EBG) structure, its dispersion diagram and application field. Based on a transmission line model, the dispersion equation is derived and theoretically investigated. In order to validate theoretical results, a full wave analysis is performed and the electromagnetic properties of the structure are revealed. The theoretical results show good agreement with the full wave simulation results. The frequency response of the structure is compared to the well know structures of Jerusalem cross and patch EBG. The results show the applicability of the proposed 2D Z-shaped EBG in microstrip patch antennas, microstrip filters and high speed switching circuits, where the suppression of parasitic surface wave is required.
 
Article
Noise is always present in offshore seismic data, as there isn't a single method that could eliminate all the forms of noise. In this study, noise removal techniques were applied to attenuate different noises in 2D shallow-marine seismic data from the Baltic Sea area. Amplitude recovery should be applied before the noise attenuation stage as a preconditioning process for showing all noises in the deeper part of the seismic data. Frequency filters (notch filter and low-cut filter), frequency-wavenumber (FK) filter, and swell noise attenuation (Deswell) were applied as robust noise attenuation techniques. The method of directly modifying the amplitude spectrum of the seismic data is known as frequency filtering. A notch filter can be used to remove the harmonic noise of the power line harmonic noise (mono-frequency noise). A low-cut filter can be used to remove the low-frequency noises due to the influence of hydrostatic pressure variations. The linearly correlated events, such as tail-buoy and operational noise, were removed using the FK filter. Incoherent noise, such as swell noise, can be attenuated by swell noise attenuation (Deswell). The seismic results are displayed before and after the applied noise attenuation techniques to prove the validity of the applied filters. This study aimed to show the importance of shallow offshore seismic data processing in removing different types of noise, as it increases the value of data for seismic data interpretation and marine geohazard assessment.
 
Article
After large-scale photovoltaic (PV) and wind power integration with the national grid, the island grid detection is a crucial technique that identifies when a grid should be considered as dead. This logic is built in an IEC61850 grid controller which mainly depends on the bus bar scheme and fault type. It becomes more complex when the ½ circuit breaker scheme is utilized. The lack of communication redundancy causes island mal-operation due to the substation's DC supply failure. In order to avoid such mal-operation discrepancies, this paper investigates the conventional islanding detection method. Then, an advanced IEC61850 grid controller 2oo3 architecture is proposed for islanding detection, based on SAS redundant communication which improves reliability. However, even if there is an interface communication failure, the power plant control center can still detect the islanding through the proposed IEC61850 grid controller and SCADA IEC60870-5-101/104 gateways integration. This method has the tendency of full supervision of the entire grid and perfect logical judgment by plant operation staff. This feasible and the proposed redundant communication architecture can play a decisive role for power system network stability in order to avoid system blackout.
 
Article
In this paper we propose a novel concept named Enhanced Multivariable Memory Polynomials (EMVP) for the behavioral modeling and linearization of Multiple Input Multiple Output (MIMO) transmitters in the presence of linear (LC) and nonlinear (NLC) coupling effects. The proposed model improves the linearization performance of the conventional Multivariable Memory Polynomials (MVP) model. Its performance is experimentally compared with the ones of three popular polynomial models. EMVP model has succeeded in offering better linearization of MIMO transmitters, with fewer coefficients, compared to the conventional models. Experimental results showed improvement in Adjacent Channel Power Ratio (ACPR
 
Article
The growing evidence of increased magnetite nanoparticles (both endo- and exo-genic) in the human brain raises the importance of assessing the entire power deposition when electromagnetic waves at GHz frequencies propagate in such tissues. This frequency range corresponds to many popular portable communication devices that emit radiation close to a human's head. At these frequencies, the current dosimetric numerical codes can not accurately compute the magnetic losses part. This is due to the lack of an implemented computational algorithm based on solving the coupled Maxwell and Landau-Lifshitz-Gilbert equations, in the case of magneto-dielectrics, considering eddy currents losses and specific properties of magnetic sub-millimetric particles. This paper focuses on analyzing the limits and the inconsistencies when using commercial dosimetric numerical software to analyze the total absorbed power in brain models having ferrimagnetic content and being exposed to 3.5GHz electromagnetic waves. Magnetic losses computed using Polder’s permeability tensor as constitutive relation lead to unreliable results. However, using such software can provide a preliminary view of the electromagnetic impact of ultra- and super-high frequencies on magnetic-dielectric tissues.
 
Article
In Electric Discharge Machining (EDM), the thermal energy used for material erosion depends on the intensity of electric sparks, the thermal conductivities of electrode material and the dielectric liquid. In this paper, the effect of EDM on AISI 304L steel is studied using copper and graphite electrodes and distilled water and kerosene oil as dielectric liquids. Material Removal Rates (MRR), Tool Wear Rates (TWR) and surface conditions are calculated for four different combinations with the two electrode materials and the two dielectric liquids. These investigations are carried out at different pulse currents. Machined surfaces are evaluated by morphological studies, energy dispersive spectrographs (EDS) and white layer thickness using Scanning Electron Microscopy (SEM). It is found that a transfer of carbon takes place from the kerosene oil and the graphite electrodes into the machined surface which alters the metallurgical characteristics, depending on the electrical and thermal conductivities of the electrode material and the dielectric liquid.
 
Article
Tungsten inert gas (TIG) is a wide common process used in fabrication due to its low cost equipment, high quality and accuracy welds but has low productivity related to the low penetration depth in single pass. A new perspective, the Activated Tungsten Inert Gas (ATIG), in which the same equipment as TIG is used, except that a thin layer of activated flux is deposited on a workpiece surface. In this work, eight kinds of oxides were tested on 316L austenitic stainless steel. Three levels of welding current were used to study the effect of different activating fluxes on weld bead geometry and mechanical properties. X-ray Photoelectron Spectroscopy (XPS) was used for the first and the second level energy for different ATIG welds to analyze the relationship between the weld shape and oxygen content in welds. The experimental results showed that the weld profile is related to the thermodynamic stability of selected oxides and in relation to the energy provided. ATIG with TiO2, SiO2, MnO2 oxides presented the deepest welds followed by Cr2O3, Fe2O3, and ZnO. Finally ZrO2, CaO oxides had no effect on the weld depth. The ATIG welded joint showed better tensile strength than TIG. The ATIG hardness measurements carried out showed also better if not the same as TIG weld except for the Silicon oxide weld. Results of the impact test showed that, except for the titanium dioxide TiO2 which has a good benefit, the weldment using the other oxide fluxes exhibits worse withstanding to sudden shock than TIG welding.
 
Article
The effects of different tempering temperatures and heat treatment times on the corrosion resistance of rolled ASTM A-36 steel in various concentrations of hydrochloric acid (HCl) and sodium chloride (NaCl) were studied in this work, using the conventional weight loss measurement. Rolled and heat-treated specimens were placed in the acidic media for five days and for seven days in NaCl, respectively, and the corrosion rates were evaluated. The microstructure of steel before and after heat treatment was studied. Corrosion resistance revealed remarkable changes from the effect of tempering after water or oil quenching of steel. Generally, the corrosion rate increases from the effect of steel hardening. Tempering of water-quenched steel at 450Co for one hour highly improves the corrosion resistance of 0.27% carbon steel.
 
Basis for rapid prototyping (std. part: motorcycle housing) IV. METHODOLOGY One should refer to the three approaches forming the verification triangle (Figure 5).
Three methods for the verification triangle [3]
Theoretical description of the qualifying process
(a) Test piece defined by CAO, (b) Piece obtained by xxx3D
Position of the test piece relative to the MMT probe
Article
This work presents geometric qualification on rapid prototyping process in the case of open access 3D printers where a working model is proposed and a prototype measurement is presented. The problem, which is to develop a methodological approach for the realization of five test pieces of equal dimensions based on complete process knowledge of the downstream material deposit movement according to XML standards, is addressed after a state of the art review. The result allows confirming the quality of the machine recommended by the manufacturer. Basically, the adopted methodology was used to fill the vacuum in the 3D FDM (open source) 3D geometric qualification (DQ) as well as to pave the way for the 3D printing processes standardization [1].
 
Article
The objective of this computational study was to propose a rapid procedure in obtaining an estimation of elastic moduli of solid phases of porous natural-polymeric biomaterials used for bone tissue engineering. This procedure was based on the comparison of experimental results to finite element (FE) responses of parallelepiped so-called representative volume elements (rev) of the material at hand. To address this issue a series of quasi-static unconfined compression tests were designed and performed on three prepared cylindrical biopolymer samples. Subsequently, a computed tomography scan was performed on fabricated specimens and two 3D images were reconstructed. Various parallelepiped revs of different sizes and located at distinct places within both constructs were isolated and then analyzed under unconfined compressive loads using FE modelling. In this preliminary study, for the sake of simplicity, the dried biopolymer solid is assumed to be linear elastic.
 
Article
This paper discusses the indirect space vector modulation for four-leg matrix converter. Four-leg matrix converter has been proven to be a reliable, cost-effective, and compact power electronic interface to supply unbalanced or nonlinear loads. However, the added fourth leg has shifted the inverter side modulation from simple two-dimension SVM into complex three-dimension. This paper employs a new technique to implement indirect 3D SVM in digital controllers with further simplification in the modulation process. Moreover, Simulink simulation using repetitive controller has been performed to regulate the output voltage for 400 Hz Power supplies.
 
Article
The objective of this computational study was to propose a rapid procedure in obtaining an estimation of elastic moduli of solid phases of porous natural-polymeric biomaterials used for bone tissue engineering. This procedure was based on the comparison of experimental results to finite element (FE) responses of parallelepiped so-called representative volume elements (rev) of the material at hand. To address this issue a series of quasi-static unconfined compression tests were designed and performed on three prepared cylindrical biopolymer samples. Subsequently, a computed tomography scan was performed on fabricated specimens and two 3D images were reconstructed. Various parallelepiped revs of different sizes and located at distinct places within both constructs were isolated and then analyzed under unconfined compressive loads using FE modelling. In this preliminary study, for the sake of simplicity, the dried biopolymer solid is assumed to be linear elastic.
 
Article
Injection process into a confined cross flow is quite important for many applications including chemical engineering and water desalination technology. The aim of this study is to investigate the performance of the injection process into a confined cross-flow of a round pipe using a single piston injection pump. A computational fluid dynamics (CFD) analysis has been carried out to investigate the effect of the locations of the maximum velocity and minimum pressure on the confined cross-flow process. The jet trajectory is analyzed and related to the injection pump shaft angle of rotation during the injection duty cycle by focusing on the maximum instant injection flow of the piston action. Results indicate a low effect of the jet trajectory within the range related to the injection pump operational conditions. Constant cross-flow was used and injection flow is altered to vary the jet to line flow ratio (QR). The maximum jet trajectory exhibits low penetration inside the cross-flow. The results showed three regions of the flow ratio effect zones with different behaviors. Results also showed that getting closer to the injection port causes a significant decrease on the locations of the maximum velocity and minimum pressure.
 
Article
It is well known that fuzzy logic can be used in the control of complex systems described by highly nonlinear mathematical models. However, the main difficulty in the design of a fuzzy controller comes with the adjustment of the controller's parameters that are usually determined by human experts' knowledge or trial and error methods. In this paper, we describe an implementation of fuzzy logic in order to reduce oscillations during the positioning of a 3D crane system. The fuzzy controller's structure is quite simple, requiring only two input variables. The proposed fuzzy controller has been applied to an experimental laboratory framework and results show that oscillations are significantly reduced.
 
Three-phase -four wire shunt active filter.
, Figure 9 and Figure 10 illustrates the performance of shunt active power filter under different main voltages, as load is highly inductive, current draw by load is integrated with rich harmonics.  illustrates the performance of Shunt active power filter under balanced sinusoidal voltage condition, THD for p-q method with PI Controller using matlab simulation is 2.15% and using RTDS Hard ware is 2.21; THD for i d -i q method with PI Controller using matlab simulation is 1.97% and using RTDS Hard ware is 2.04% . Figure 9 illustrates the performance of Shunt active power filter under un-balanced sinusoidal voltage condition, THD for p-q method with PI Controller using matlab simulation is 4.16% and using RTDS Hard ware is 4.23; THD for i d -i q method with PI Controller using matlab simulation is 3.11% and using RTDS Hard ware is 3.26%.
Article
This paper presents a control strategy for a three phase four-wire shunt active filter. The shunt active filter is a custom-power device capable to compensate, in real time, harmonics and unbalances in an electrical system. The main objective of this paper is to analyse the performance of instantaneous real active and reactive power (p-q) control strategy for extracting reference currents of shunt active filters under balanced, un-balanced and balanced non-sinusoidal conditions with PI controller in MATLAB/Simulink environment and also with Real Time Digital Simulator (RTDS) Hardware. When the supply voltages are balanced and sinusoidal, the all control strategies are converge to the same compensation characteristics; However, the supply voltages are distorted and/or un-balanced sinusoidal, these control strategies result in different degrees of compensation in harmonics. Extensive simulations are carried out with PI controller for p-q control strategy under different main voltages. The 3-ph 4-wire SHAF system is also implemented on a RTDS Hardware to further verify its effectiveness. The detailed simulation and RT DS Hardware results are included.
 
Article
In this study, a milling experiment was performed, with 3x13 steel selected as the experimental material along with TiAlN coated inserts. The Box-Behnken method was used to design the experimental matrix with a total of eighteen experiments. Cutting speed, feed amount, and depth of cut were selected as the input parameters. Three regression models of surface roughness have been established, one using the experimentally measured surface texture, one using the Johnson transform to convert the surface texture data, and one using Box-Cox transformation to convert the surface texture data. A comparison of the accuracy of the three models was performed. The results show that the model using the Box-Cox transformation has the highest accuracy, followed by the model using the Johnson transformation. In addition, the influence of cutting parameters on surface roughness is also discussed in detail.
 
Article
A low power, low phase noise adaptive bandwidth phase locked loop is presented in this paper. The proposed structure benefits from a novel lock status monitor unit (LSMU) that determines loop operation and loop bandwidth. The loop filter resistance and charge pump current are inversely proportional and bandwidth to reference frequency is maintained fixed. This structure is simulated in 0.18 μm CMOS technology and simulation results are presented.
 
Article
AISI 420 martensitic stainless steel is used for making gas and steam turbine blades, steel balls and medical instruments, due to its anti-corrosive properties. Turning of AISI 420 SS would be a worthy procedure specifically in manufacturing high surface finish parts. In this work, effort has been made to investigate the cooling and lubricating performance of SiO2 (silicon dioxide) nanoparticles at different weight concentrations of 0.1g, 0.5g and 1g mixed in a novel developed base fluid (synthetic). The performance of optimum SiO2 based cutting fluid is evaluated based on the turning process with output responses like surface finish and cutting temperature. Taguchi technique was used with standard L9(3**4) orthogonal array. The responses, surface roughness, and cutting temperature were analyzed using S/N (signal-to-noise) and ANOVA (analysis of variance). This analysis identifies the significant input parameter combination to obtain minimum surface roughness and temperature.
 
Article
The production of hydrogen from Poly Ethylene Terephthalate (PET) using CT 434 ZSM-5 is investigated in this research study. Gas chromatography equipped with a thermal conductivity detector is used to detect the amount of hydrogen produced at different temperatures. The Chromatograph spectrum of pure hydrogen as well as the spectra of evolved gases at 250oC, 280oC, 310oC and 340oC are obtained to validate the presence of hydrogen. The spectra of percentage of hydrogen and peak area to height ratio with increasing temperature shows a similar trend except at the temperature of 340oC. Maximum hydrogen percentage of 20.11% is found in the evolved gases collected at temperature of 250oC. The retention time of sample collected at 340oC is very close to reference retention time 2.014 min observed for a pure hydrogen sample.
 
Pressing and heating of the Ti-6-4 powder
Wear resistance friction coefficient change for Group A
SEM image of heat-treated specimens at ×500 for B2 (layer thickness: B2=10.4µm)
Article
Titanium alloys are widely used due to their high performance and low density in comparison with iron-based alloys. Their applications extend to aerospace and military in order to utilize their high resistance for corrosion. Understanding the mechanical properties and microstructure of titanium alloys is critical for performance optimization, as well as their implications on strength, plasticity, and fatigue. Ti-6Al-4V is an α+β two-phase alloy and is considered one of the most commonly used titanium alloys for weight reduction and high-performance. To avoid manufacturing defects, such as porosity and composition segregation, Hot Isostatic Pressing (HIP) is used to consolidate alloy powder. The HIP method is also used to facilitate the manufacturing of complex structures that cannot be made with forging and casting. In the current research, Ti-6Al-4V alloys were manufactured with HIP and the impact on heat treatment under different temperatures and sintering durations on the performance and microstructure of the alloy was studied. The results show changes in mechanical properties and microstructure with the increase of temperature and duration.
 
The laser cutting machine AMADA AS 4000 E.
The 3D-SurfaScan optical profilometer.
Sz as a function of V for three values of p.
Sz as a function of p for three values of V.
Article
This paper investigates high power CO2 laser cutting of 5mm-thick Ti-6Al-4V titanium alloy sheets, aiming to evaluate the effects of various laser cutting parameters on surface roughness. Using multiple linear regression, a mathematical model based on experimental data was proposed to predict the maximum height of the surface Sz as a function of two laser cutting parameters, namely cutting speed and assist-gas pressure. The adequacy of the proposed model was validated by Analysis Of Variance (ANOVA). Experimental data were compared with the model’s data to verify the capacity of the proposed model. The results indicated that for fixed laser power, cutting speed is the predominant cutting parameter that affects the maximum height of surface roughness.
 
Experimental set-up.
Workpiece specimen.
Multiple response optimization analysis results.
Article
Titanium and its alloys give immense specific strength, imparting properties such as corrosion and fracture resistance, making them the right candidate for medical and aerospace applications. There is a wide range of engineering applications that use titanium alloys in a variety of forms. The cost of these alloys is slightly higher in comparison to other variants due to the problematic extraction of the molten process. To reduce costs, titanium alloy products could be made by casting, isothermal forging, radial swaging, or powder metallurgy, although these techniques require some kind of finishing machining process. Titanium and its alloys are difficult to machine due to skinny chips leading to a small cutting tool-workpiece contact area. The thermal conductivity of titanium alloys is too low and the stress produced is too large due to the small contact area, which results in very high cutting temperatures. This paper deals with the experimental study of the influence of the Minimum Quantity Lubricant (MQL) environment in the milling of Ti-6Al-4V alloy considering the optimization of surface roughness and production rate. Taguchi-based TOPSIS and ANOVA were used to analyze the results. The experimental results show that MQL with vegetable oil is successfully applied in the milling of Ti-6Al-4V. The research confirms the suitability of TOPSIS in solving the Multiple Criteria Decision Making (MCDM) issue, by choosing the best alternative at Vc=120m/min, fz=0.065mm/tooth, and ap=0.2mm, where the surface roughness and material removal rate are 0.41µm and 44.1492cm3/min respectively. Besides, ANOVA can be used to predict the best parameters set in the milling process based on the regression model. The parameters predicted by ANOVA analysis do not coincide with any implemented parameters
 
Article
This paper presents a low-profile, wearable textile antenna, designed for Wireless Body Area Network (WBAN) applications operating in the 5.8GHz band for Industrial, Scientific, and Medical (ISM) applications. An Artificial Magnetic Conductor (AMC) structure was used to improve antenna performance and protect the human body from back-radiation. The antenna with the integrated AMC achieved a measured gain of 8.92dBi, an efficiency of 80%, a wide impedance bandwidth of 1.4GHz (24.1%), and SAR values of 0.00103 and 0.00034W/Kg for 10g and 1g tissues respectively. The proposed antenna was studied in a worn-on-body scenario using a multilayer numerical model of the human body. The influence of the thickness of each tissue layer of the human body was investigated. The results showed that the antenna maintained its performance, a stable gain was obtained, and the SAR values were also below the IEEE guidelines that guarantee the safety of the wearer.
 
Top-cited authors
Ziad Alqadi
  • Al-Balqa' Applied University
Dionisios Pylarinos
  • Hellenic Electricity Distribution Network Operator S.A. (HEDNO S.A.)
Majed Omar Dwairi
  • Al-Balqa Applied University
Amjad Hindi
  • Al-Balqa' Applied University
Kiriakos Siderakis
  • Hellenic Mediterranean University