International Journal of Engineering
Volume:36 Issue: 9, Sep 2023

This article proposes a new engineering approach to detect targets using multi-static radars. It considers the aperture angle and the probability of false alarm of detection which allow to improve the performances of the radar system deployment. This proposed method is tested on three tomographic modes of multi-static radars: Single Input Multiple Output (SIMO), Multiple Input Multiple Output (MIMO), and Synthetic Aperture Radar (SAR). In this work, a calculation and estimation method for the parameters (spacing sensor and tilt angle of baseline) are developed using the deployment of the radar system based on geometrical arrangements. Employing these parameters, estimated by the proposed approach, and using them for the calculation of the tomographic resolution, the nearest ambiguity location, and the scan loss which are radar deployment performances. The results show that the spacing between sensors varies from 40 to 70% with an increment of aperture angle from 15° to 30° and the step of variation in the false alarm probability of detection. The length of the radar system deployment is also reduced by 6.66%. This approach improves the capabilities of distinction of the targets in a multi-static radar system and allows a reduction in deployment costs.

Depleting good quality natural aggregates and soils call for the need of use of industrial by-products and waste materials in road construction. Use of wastes and by-products in road construction consume large quantities and resolve issue of their safe disposal. Class C fly ash is the by-product from thermal power plants while quarry dust is waste left behind during quarrying processes. This study investigated the application of class C fly ash and quarry dust mix for utilization in subbase layer of flexible pavement. The class C fly ash and quarry dust mixed were studied with the help of unconfined compressive strength test, repeated load triaxial test, durability test and microstructural analysis. The mixture of 90% fly ash plus 10% quarry dust was found to be suitable with respect to strength and durability criteria to be used as subbase material in flexible pavement. Owing to the formation of cementitious phases during pozzolanic reaction, proposed mix demonstrated significantly higher resilient modulus than conventional granular subbase material. The service life ratio for pavement with proposed mix is 1.2 and 1.26 in fatigue and rutting respectively compared to conventional pavement. The use of quarry dust and fly ash in large quantities in flexible pavement is an economical as well as sustainable solution for road construction.

The growing need of the population for energy and hydrocarbon fuel, leads to an accelerated pace of development of the oil industry. In this regard, there is a need to develop new or renew the development of old oil fields. Among a range of existing EOR methods, the use of surfactants is considered as one of the main options aimed for both raising oil production and improving oil recovery. In this work, a study was carried out to define the characteristics and criteria for selection of an effective surfactants which are used in the tertiary scheme of recovery (IOR or EOR) from reservoir formations and especually during Enhanced Oil Recovery (EOR) flooding system. Three cationic surfactants with specific trade names were used in this study. It has been revealed that addition of surfactants positively affects inhibition of clay issues even in a more efficient manner than potassium chloride as one of the most widespread used clay inhibitors. At the end, a comprehensive discussion and suggestions are provided on the importance of temperature, concentration and bottom-hole conditions that affect selection of an optimum surfactant.

Accurate land cover classification from the digital surface model (DSM) obtained from LiDAR sensors is a challenging topic that researchers have considered in recent years. In general, the classification accuracy of land covers leads to low accuracy using a single-band DSM image. Hence, it seems necessary to develop efficient methods to extract relevant spatial information, which improves classification accuracy. In this regard, using spatial features based on morphological profiles (MPs) has significantly increased classification accuracy. Despite MPs' efficiency in increasing the DSM's classification accuracy, the classification accuracy results under the situation of limited training samples are not still at satisfactory levels. The main novelty of this paper is to propose a new feature space based on local kernel descriptors obtained from MP for addressing the mentioned challenge of MP-based DSM classification. These innovative feature vectors consider local nonlinear dependencies and higher-order statistics between the morphological features. The experiments of this study are conducted on two well-known DSM datasets of Houston and Trento. Our results show that support vector machine (SVM)-based DSM classification with the new local kernel features achieved an average accuracy of 93.75%, which is much better than conventional SVM classification with single-band DSM and MP features (by about 57% and 11.5% on average, respectively). Additionally, our proposed method outperformed two other DSM classification methods by an average of 4.7%.

Nowadays Quantum-dot Cellular Automata (QCA) is one of the new technologies in nanoscale which can be used in future circuits. Most digital circuits are implemented with CMOS technology, but CMOS has some problems like power consumption and circuit size. So, for solving these problems a new method (QCA) is presented. It is clear that converters play a crucial role in the digital world. So, due to the aforementioned point, in this paper, two digital code converters, containing an excess-3 to decimal, and a decimal to excess-3 code converter are presented. The tile method is used to design proposed circuits in quantum-dot cellular automata (QCA) nanotechnology. The tile method gives a unique block for the majority and NOT gates. This property facilitates integration. Both of the proposed code converters have 1.75 clock cycles delay and have an energy dissipation of about 100meV. In the excess-3 code to decimal converter, 516 cells are used, which occupy an area equal to 0.43µm2 also in the decimal to excess-3 code converter. 321 cells are used, which occupy an area equal to 0.28 µm2.

The corrosion of reinforced concrete (RC) is a leading cause of structural failures and engineering problems in current infrastructural aspects; making corrosion monitoring of reinforcements in concrete structures highly important especially from safety point of view. Non-destructive testing (NDT) methods are useful approaches for in-situ detection and evaluation of steel corrosion in RC for monitoring time trend of corrosion of rebars. Recently, some NDT methods such as magnetic and resistive sensors as well as electrochemical monitoring methods such as electrochemical impedance spectroscopy were develop for RC rebar corrosion monitoring. This paper presents a novel approach using modern smartphones equipped with magnetic sensors and commercially available analog Hall-Effect sensors to monitor rebar corrosion within the concrete .Results showed a reasonable sensitivity of the methods to detect and monitor corrosion of rebars with time. In order to check and validate the data obtained in this study, another non-destructive electromagnetic test by a search coil connected to a LCR meter was used to monitor corrosion. The results obtained with this method were consistent with the previous methods. In other words, by using these three methods, it is possible to successfully monitor and determine the severity of corrosion.

In this study, five one-way brick slab specimens were manufactured to investigate the behavior of brick slabs composed of various types of bricks (solid bricks, perforated bricks, and cellular concrete blocks (thermostone). The span ranges from 600 to 800 mm, while the camber ranges from 0 to 30 mm. Previously, cellular concrete blocks, solid and perforated clay bricks were employed as the building materials. These samples were tested by being subjected to flexural three-point loading. The results revealed that increasing camber by 30 mm for solid brick specimens increased ductility, and ultimate strength, by 5.5% and 77.62, respectively. Increasing the span from 600 to 800 mm for solid brick specimens decreased the ultimate strength and ductility by 37.96% and 6.83%, respectively. Cellular concrete blocks can be used in the construction of slabs due to their lightweight and acceptable structural response when compared to solid brick specimens. Due to their good structural performance and lightweight, perforated bricks can be used to build brick slabs. Brittleness and the sudden collapse of the brickwork arch characterized the failure mode in all samples.

This work presents an experimental study that investigates the behavoir of both conventional and under-reamed piles embedded in a single layer of sand with varying relative densities and examines piles in different soil layers, subjected to pullout static monotonic loading. The study focuses on the influence of the spacing ratio between under-reams and the number of bulbs on the pile's ultimate pullout load. A uniform pile stem, a pile with a single bulb, and a pile with twin bulbs were the three varieties of small-scale models of aluminum piles that were utilized. The pile's measurements were 25 mm in shaft diameter by 550 mm in height, with a 62.5 mm bulb diameter. To establish their impact on the uplift capability of an under-reamed pile in sand, the current work examines the location, spacing between bulbs, and the number of bulbs. At 35% relative density, the influence of various bulb spacing ratios S/Du is investigated (S/Du =1.0, S/Du = 1.25, S/Du = 1.5, S/Du = 1.75, and S/Du = 2). The test results revealed that the maximum ultimate pullout capacity is achieved when the bulb spacing ratio is S/Du =1.5. The pullout capacity increases 3.5 times for a single bulb and 7 times for a double bulb compared with a straight pile under the same condition, as well as an under-reamed pile in a dense or medium sand layer overlain by loose sand rises to a peak before capacity declines. Load-displacement curves and initial stiffness improve compared to homogeneous, loose, sandy soil.

We have designed and simulated a 10-nanometer regime gate High Electron Mobility Transistor (HEMT) with an undoped region (UR) under the gate with high k dielectric as hafnium oxide (HfO2). The thickness of metal gate(G) and undoped regions are equal but length of channel(C) is not equivalent. The proposed Undoped under the gate dielectric High Electron Mobility Transistor reduces the maximum electric field(V) in the channel region and increases the drain current significantly. The High-K dielectric High Electron Mobility Transistor structure obtained a saturated Ion current of 60% higher than the conventional structure. For High critical Power and High-frequency Power transmission Amplifiers utilizes the AlGaN/GaN/SiC-based High Electron Mobility Transistor with an undoped region under the gate with High-K Hafnium oxide. The Proposed advanced High Electron Mobility Transistor Produces a higher Drain current (Id), 54% high transconductance (Gm) with Low On-Resistance (Ron), and High conductivity in comparison to typical High Electron Mobility Transistor. In Addition to these improved characteristics, the Electric field along the Y direction is also observed. The proposed structure formed by Low-k Dielectric materials in the process of Silicon Dioxide(SiO2) and High-k dielectric being Titanium Dioxide (TiO2) and Hafnium Oxide (HfO2) created more opportunities in Power electronics and radio frequency operations.

Structure health monitoring is still a challenging issue despite continuous research efforts since a long time. Modeshape changes are a remarkable symptom of the damaged element location in structural system identification. In this paper, various mode shape based prediction techniques are applied to a common structural model. A cantilever beam model is formulated using the distributed mass and stiffness matrix based finite element modelling. Multiple damages are introduced in the above cantilever beam even with two, three and four member damage combinations. The results does not provide a concrete solution on the damage element location prediction. Further, in the computational part, the distributed computing technique using element-to-element matrix multiplications is applied. The Roving technique is also applied, which acts as a counter for self-automation. The proposed approach provides a better damage element location prediction even for the multiple damaged member combinations. The roving technique means an element scanning technique, which works with a computer clock speed. The novelty of the approach is that the method is simple and it could be applied to other structures. While scanning as automation no element is left out. Another beauty of the method is that no prior damage elements are assumed as many statistical based approaches assumed in prior. This approach could be a better way to the automation process, for the system identification and machine learning tools.

The integration of Internet of Things (IoT) and cloud-based cathodic protection (CP) systems is an innovative approach that can lead to improve pipeline protection from corrosion. Using a printed circuit board (PCB) to measure and control current and voltage makes it possible to monitor PC systems in real time. The web interface that is connected to the PCB circuit through IoT technology provides a platform for instant evaluation of the data obtained, thereby enabling early detection of potential problems. One of the key benefits of real-time monitoring is improved data management and security. The data obtained can be stored on a cloud server, making it easier to access and analyze. This eliminates the need for manual inspections, which can be time-consuming and error-prone. Additionally, real-time monitoring can reduce downtime, as problems can be detected and resolved quickly, preventing the need for lengthy manual inspections and maintenance. This innovative approach has tremendous potential for the future of pipeline protection and corrosion control. The developed PCB circuit features a mobile UART that provides program protection, and the interface can control multiple PCB cards and relays independently. The monitoring system can be updated without interrupting data acquisition. The use of open-source software, database hosting, and low-cost PCB development facilitates commercialization. This study could inspire new applications in asset management and monitoring.

Catalytic pyrolysis of Ulva lactuca macroalgae was studied over Amberlyst-15 catalyst at temperature 400, 500, and 600 oC. The comparison between catalytic and non-catalytic pyrolysis in the conversion of Ulva lactuca was determined. Intriguingly, it was found that Amberlyst-15 catalyst improved bio-oil production efficiency. The highest bio-oil yield of 29.54 wt% was achieved at 600 oC with the presence of an Amberlyst-15 catalyst. Furthermore, Amberlyst-15 catalyst could enhance gas production by over 73.88%. It could be attributed due to the catalytic pyrolysis could promote more small molecules that are more volatile through a cracking process. Elemental and functional groups in pyrolytic bio-oils were identified via GC-MS analysis. The acidity and structure of Amberlyst-15 catalyst significantly affected the distribution of product components, especially the formation of aromatic hydrocarbons, with a 27.78% relative yield. The first-order kinetic model showed that the production of aromatic hydrocarbons follows Arrhenius law.

A design of a wideband bidirectional pattern antenna, accomplished by the integration of a circular patch, crescents as parasitic elements, encompassed by a circular ring adjoining the ground plane, to operate over the mid-band 5G sub-6 GHz applications is reported. It is come up with a copper grazed on FR4 substrate with relative permittivity of 4.3 and height of 1.6 mm. The proposed antenna is fed by a 50-ohm coplanar waveguide, which is printed on the same side of the radiating circular patch. A concise antenna model with dimensions of 45 × 45 × 0.6 mm3 was made up and investigated to affirm the simulation outcomes. Good consistency was confirmed between experimental and simulation results. The proposed antenna has the benefit of bidirectional pattern with a good gain of 5.24 dBi and wide bandwidth covering of 111.4% (1.81-6.36 GHz) — it is one of good postulants for 5G new radiation application especially for indoor environment, narrow, and long path services area like corridor, tunnel, and train station, etc.

Today, contrary to the benefits and advantages that the use of polymer materials has had for humans, the use of these materials has caused environmental problems for human life due to their non-degradability in nature. Therefore, the use of biodegradable polymers such as polylactic acid (PLA) is increasing. One of the main applications of plastic materials is the production of disposable containers. In this research, the thermoforming process of PLA sheets reinforced with graphene oxide nanoparticles (nGO) (0.4 and 1 wt.%) was investigated. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to study the morphology of the samples before and after thermoforming. The mechanical properties before and after the thermoforming process were investigated by tensile test. The results showed that after the thermoforming process, the tensile strength of the sheets significantly increased, so that for the sample containing 1wt.% of nGO, the tensile strength increased by about 70%. The results of the thickness distribution investigation showed that the lowest amount of thickness reduction, approximately 68%, is related to the sample containing 1 wt. % of nGO. The results of the DSC thermal test showed that the degree of crystallinity of the samples significantly decreased after thermoforming.

Energy consumption and throughput optimization in cognitive radio networks (CRNs) are two critical issues that have attracted more attention in recent years. In this paper, we consider maximization of the energy efficiency and improvement of the throughput as optimization metrics for jointly optimizing sensing times and energy detection thresholds in each sub-channel and selecting the spectrum sensing (SS) and data transmitting multi-antenna secondary users (SUs) in multi-channel multi-antenna CRN under constraints on the probabilities of false alarm and detection. The considered problem is solved based on the convex optimization method and the algorithm having less computational complexity compared to baseline approaches is proposed to achieve the optimal parameters and goals of the problem. The performance of the proposed scheme is evaluated by simulations and compared with the other methods. The results indicate that the proposed approach can achieve less energy consumption while the minimum required throughput is guaranteed.