International Journal of Engineering
Volume:35 Issue: 10, Oct 2022

Incidents that occur suddenly due to natural and human functions and impose hardships on society are called crises. As the Earth’s climate changes have increased the number of natural crises, including earthquakes, floods, hurricanes, etc., in recent years, human beings have felt the need for crisis management and the necessary planning in critical situations more than ever. This research aims to model and solve the problem of location, allocation, and inventory in post-crisis conditions. To meet this purpose, first, we have conducted a review of the previous papers. Then, we have identified the research gaps in management and planning in critical situations. In this study, uncertain budgets and demands and bi-level programming decision-making are the innovations. As a result, we have developed mixed-integer linear mathematical models to cover the research gaps. Finally, several problems have been solved in small dimensions by GAMS software and large-sized problems by genetic and electromagnetic meta-heuristic algorithms. Then, we analyzed the algorithms’ performance which indicates the genetic algorithm is better than the electromagnetic algorithm in this issue.

The bio-mediated soil improvement techniques have been gaining increasing attention recently. In this method, the bacteria was cultivated aerobically in the laboratory and added to the soil with reactant solutions such as urea and calcium chloride. Most of the existing studies are on sandy soils and few researches have been done on silty sandy soils. However, most soils in nature are compounds of fine-grained and coarse-grained soils. In fine-grained soils, silt does not have very good resistance due to the lack of adhesion between its particles. Hence, in this study Sporosarcina pasteurii bacterium was cultivated aerobically for stabilizing sand with different percentages of silt to determine the optimum bacteria suspension volume. After some bacterial tests such as measuring bacterial growth, standard plate count, gram staining, pH determination, growth without urea, and urease test, geo-technical tests like soil sieve, compaction, and Atterberg limits were also done. Standard plate count was estimated 2.5*108 through serial dilution plating and culture media pH was determined 8.64 from different samples. Moreover, to achieve the best results, different sampling methods were compared. As the calcium carbonate creates a network of calcified bridges of calcite between sand grains, an electron microscope was used for scanning the surface with a focused beam of electrons. Results of triaxial tests show that the maximum strength for samples with 0%, 10%, 20%, 30% and 40% of silt was improved from 700, 900, 750, 600 and 550 to 1100, 1400, 1550, 1600, and 1500 kPa respectively by adding optimum bacteria suspension volume.

A series of inductor loads may not be the best design criterion for improvement in circuit performance. In this work, the best compromise so far for the trade-off in power consumption, input referred noise current spectral density, with wide bandwidth, high transimpedance gain and low DC supply voltage is reported. A simulated 65 nm CMOS feedforward transimpedance amplifier is introduced with a series of single PMOS loads instead of a series of inductor loads. A bandwidth of 20.16 GHz with a transimpedance gain of 51.16 dBΩ, an input referred noise current spectral density of 34.3 p A⁄√Hz, a power consumption of 1.052 mW and with a 1V DC supply voltage are presented. In addition, an active inductor load (instead of inductor load) is introduced within the 65 nm CMOS feedforward transimpedance amplifier. A bandwidth of 3.75 GHz with a transimpedance gain of 42.7 dBΩ, an input referred noise current spectral density of 21.4 p A⁄√Hz, a power consumption of 0.66 mW and with a 1V DC supply voltage are reported.

A concept to heal the damaged surface through healing agents in metallic composites is expensive, as the selection of design parameters for such new generation smart composites are at their initial developmental stage. In the present study, the two case studies based on self-healing smart structure are included with different input design parameters to evaluate the mending of crack after healing. Taguchi based L8 experiments were conducted to analyze the influential parameters responsible for higher self-healing assessments (i.e. recovery in crack width, recovery in crack depth and flexural strength recovery). For evaluating the self-healing assessments, a soft computing technique based on S/N ratio obtained for ANOVA analysis is considered for constructing the fuzzy logic predictive model. Further, Linear regression models i.e. a statistical tool is generated to judge the accuracy of the predicted model through various error analyses. Based on S/N ratio Fuzzy logic model, results show less error values of 6.33 % and 4.94 % for case study-I and case study-II respectively in comparison to the regression model adapted for all self-healing assessments. This provides a close resemblance with the experimental observations even with less number of experimental runs. It concludes that the fuzzy logic model provides a powerful soft computing tool to perform large research work related to the design of input parameters for metallic based self-healing composites structures in near future.

Face recognition is one of the most common authentication techniques widely used due to its easy access. In many face recognition applications, captured images are often of low resolution. Face recognition methods perform poorly on low resolution images because they are trained on high resolution face images. Although existing face hallucination methods may generate visually pleasing images, they cannot improve the performance of face recognition methods at low resolution as the structure of the face image and high-frequency details are not sufficiently preserved. Recent advances in deep learning have been used in this paper to propose a new face super-resolution approach to empower face recognition methods. In this paper, a Generative Adversarial Network is used to empower face recognition in low-resolution images. This network considers image edges and reconstructs high-frequency details to preserve the face structure. The proposed technique to generate super-resolved features is usable in any face recognition method. We have used some state-of-the-art face recognition methods to evaluate the proposed method. The results show a significant impact of the proposed method on the accuracy of face recognition of low resolution images.

Among the intermediate metal diborides, HfB2 and ZrB2 are the most suitable options for high temperature applications. Compounds such as borides, carbides and nitrides of the IV-V group intermediate metals, which have melting temperatures above 3000 °C [1], are known as ultra high temperature ceramics (UHTCs). In this study, HfB2-SiC-graphite composites have been fabricated using spark plasma sintering at 1900 ℃ for 10 min. The effect of graphite content on microstructure, mechanical properties were studied and also oxidation resistance of prepared composites was investigated at 1400 ℃ for 32 h. Weight changes and the thickness of formed oxide layer was measured. The relative density, toughness and strength of SPSed composites were increased with inccraesing of graphite up 2.5 wt% and then decraesed. The hardness of composites were decreased when graphite was added. The oxidation resistance of composite improved after graphite addition up 2.5 wt%, while ecessive quantity of graphite caused to poor oxidation resistance of composite.

The expansion of the online food delivery apps (OFDAs) around the globe has accelerated because of the sudden growing cases of the COVID-19 pandemic. OFDAs are quickly expanding in India, providing a huge number of chances for different OFDA platforms and creating a competitive market. There are several criteria and dimensions for OFDAs businesses to explore to keep with the frequently changing competitive market and achieve long-term success. A Pythagorean fuzzy set (PFS) is a powerful tool for dealing with uncertainty. Distance measure of PFS is a hot research topic and has real-life applications in many areas, such as decision making, medical diagnosis, patterns analysis, clustering, etc. The article aims to examine the results of the novel Pythagorean fuzzy distance measure strategy to select the best online app using TOPSIS method to select the best OFDAs. Firstly, all the axioms related to distance measures are proved for the proposed measures. The proposed work uses five distinct alternatives/options and four attributes/criteria in a fuzzy environment to deal with imprecise and conflicting information. The findings indicate that the proposed methodology is a more realistic way to choose the best OFDAs among others. Finally, a sensitivity analysis is used to determine whether the chosen alternative was the best option among the other components and to ensure that the TOPSIS technique results were accurate.

In this study, the effect of PCL coating on the mechanical strength, cell behavior and cell attachment of the hierarchical meso/macroporous Titania scaffold were investigated. The Titania scaffold as the substrate was fabricated through the evaporation-induced self-assembly coupled with the foamy method. Then prepared scaffolds were coated by polycaprolactone solution with three different weight percentages by the dip-coating method. SAXS, WAXRD, SEM, compressive strength, MTT and cell attachment test were applied to characterized the samples. Based on XRD results, as polycaprolactone concentration increased, the intensity of the crystalline polycaprolactone phase increased while the TiO2 peak intensity decreased due to the covering of mesoporous titania by polycaprolactone. Compressive strength showed that by increasing polycaprolactone percent, the porosity decrease from 89.5 to 73.8 % which caused increasing strength from 0.2 to 0.79 MPa. The SEM results illustrated that by increasing polycaprolactone concentration from 1.2 to 1.5 wt%, the macrospores were filled by polycaprolactone. In this regard, The sample containing 1wt% polycaprolactone was choosen as the selective sample. Also, the MTT test reported a small trace of cytotoxicity in contact with the L929 mouse fibroblast cells. The cell attachment test that was performed by using MG63 cells, showed that the coated samples provided the suitable substrate for cells to attach and also showed cell viability on the surface of the coated substrate. Overall, according to the results, the hierarchical meso/macroporous Titania scaffold coated with 1 wt% polycaprolactone, could have good potential to use in tissue engineering.

In the present paper, an innovative fire-earthquake resistant joint called high-performance tube (HP-T) connection is presented and numerically validated. This HP-T connection improves the axial and rotational ductility as well as prevents brittle failure. Two series of models were simulated in ABAQUS software. In the first set of models, which was designed for heat simulation, a sequentially coupled thermal-stress analysis was performed to investigate the effects of different parameters such as web and flange tube thickness and the ratio of the applied load. To simulate the fire damage, two probable scenarios were considered: bottom flange tube damage and beam web damage when exposed to combined initial loading and fire. In the second set of models for seismic simulation, the failure mode, hysteretic curves, and strain distribution were analyzed. According to the results, HP-T robust connection not only provides appropriate ductility enhancement in force-variable fire conditions but also withstands at least 8% inter-story drift without considerable strength reduction.

When it comes to evaluating mining projects, uncertainty plays a significant role, particularly in the analysis of mining economic characteristics, which makes the assessment of a mining project erroneous and untrustworthy. The volatility of mineral prices is a major cause of economic ambiguity and concern. Economic uncertainty has extensively been examined in mining production project planning, but the majority of the study has focused on single-element deposits, with little emphasis devoted to the significance of pricing uncertainty in two-element deposits. Using a three-dimensional tree model, this study investigates how design could be affected by the pricing uncertainty of two different elements. In this model, not only annual volatility but also monthly volatility are considered due to momentary changes in the price of several elements. To authenticate the proposed model, a numerical example was resolved using discounted cash flow, binomial tree, pyramid tree, and three-dimensional modeling techniques, and the results of each approach were compared to those of real-world data. Following the findings of the current investigation, it can be concluded that the values derived from the suggested model (a net present value of $ 324.2 thousand) are more precise than the values acquired from other approaches, and that they are just 8% out of step with reality. Other methods, on the other hand, come up with results that are at least 17% and at most 39% different from those that come from real data.

With ever increasing demand of IoT based sensor systems, there is a need to assess the performance of  wireless sensor networks especially in indoor environment. In these networks, antenna plays an important  role. The performance of onboard antenna of the sensor module  with respect to its height and orientation are examined in this paper. Several experiments were carried out mostly in indoor environment by changing orientation and height of the antennas. The performance is assessed on the basis of Received Signal Strength (RSS) and its modelling using linear, logarithmic and rational polynomial regression techniques which will characterize the channel in a particular environment.   Out of all the combinations in terms of height of the antennas and their orientation, it is found for a given indoor environment, with transmitting antenna at a medium height facing upwards and receiving antenna with an inclination of 700  towards transmitter resulted in  better performance with R2poly value of 86.81% and RMSE of 4dB. Therefore, this combination is suggested for wireless sensor networks in indoor environment for achieving the of cost-effective energy-efficient green IoT. The analysis would be useful for improving the efficiency and coverage of wireless sensor networks.

Pozzolans are supplementary cementitious materials (SCMs) that many researchers have found suitable for partial replacement of cement in concrete in order to reduce the environmental hazards and energy consumption involved in the production of concrete. However, these materials have been seldomly used in the present day construction industry especially in Nigeria, in spite of notable research efforts on them over the past decade and abundance of evidence to support their tremendous benefits. A question therefore naturally arises: What is responsible for the hesitation in applying pozzolans widely in the construction industry? This paper investigated by means of a research survey the reasons for their low acceptance and adoption by stakeholders in the construction industry. Opinions from 82 respondents of impressive involvement in the construction industry were collated and statistically analyzed using non-parametric tests, namely Cronbach’s Alpha Reliability, Kruskal-Wallis H and Mann-Whitney U tests. The results of the analyses affirmed that pozzolans are effective in mitigating the negative environmental effects caused by using conventional cement in concrete. It further revealed that notable factors militating against their adoption in the construction industry include unavailability of relevant mixture design standards for pozzolanic concrete, lack of commercial production of pozzolanic concrete, unavailability of sufficiently skilled professionals on pozzolan application, inadequate public awareness, lack of policies recommending and guiding its use, and fears on results achievable with use of pozzolans. Respondents generally agreed that development of proper guidelines and standards, as well as adequate public awareness will favour wide acceptance and industrial application of pozzolans.

Fall is one of the most critical health challenges in the community, which can cause severe injuries and even death. The primary purpose of this study is to develop a deep neural network using wearable sensor data to detect falls. Most datasets in this field suffer from the problem of data imbalance so that the instances belonging to the Fall classes are significantly less than the data of the normal class. This study offers a dynamic sampling technique for increasing the balance rate between the samples belonging to fall and normal classes to improve the accuracy of the learning algorithms. The Sisfall dataset was used in which human activity is divided into three categories: normal activity (BKG), moments before the fall (Alert), and role on the ground (Fall). Three deep learning models, CNN, LSTM, and a hybrid model called Conv-LSTM, were implemented on this dataset, and their performance was evaluated. Accordingly, the Conv-LSTM hybrid model presents 96.23%, 98.59%, and 99.38% in the Sensitivity parameter for the BKG, Alert, and Fall classes, respectively. For the accuracy parameter, we have managed to reach 97.12%. In addition, by using noise smoothing and removal techniques, we can hit a 97.83% accuracy rate. The results indicate the proposed model's superiority compared to other similar studies.

This study presents the ATENA-3D simulation of natural aggregate concrete (NAC) and recycled aggregate concrete (RAC) beams subjected to pure torsion and the beam was validated by the experimental results with corresponding outputs. All the test specimens were 150 mm wide, 250 mm, deep and 1800 mm long. The natural coarse aggregate (NCA) were replaced by coarse recycled concrete aggregate (RCA) at three replacement ratios of 0 %, 50 %, and 100 % to prepare concrete. All the beam specimens were simulated and tested to assess the parameters like torque, twist, crack pattern, stiffness, and toughness in pure torsion. The comparison of ATENA-3D and experimental results showed that torque resistance capacity, stiffness, and toughness of beams decreased as the % of RCA increased in the concrete. A similar torque-twist curve pattern was observed in simulation and experimental studies. All the specimens failed due to torsional cracking. The torsional capacity of the beams in ATENA-3D software was higher by 9.80 %, 10.67 %, and 12.80 % than the experimental results. The results reveal that varying the quantity of RCA in RAC does not compromise the pure torsional behavior of the beam in both methods. Also, it can be concluded that the use of RCA in RAC is acceptable for structural concrete beams in pure torsion.

Large bone defects caused by trauma or disease needs extra intervention. Gelatin/chitosan complex is one of the most valuable compositions for bone healing, but fast degradation in aqueous solution and low mechanical properties increase the need for cross-linking agent. The cross-linker concentration and cross-linking method had a significant effect on the properties of fabricated scaffolds. Here, three different cross-linking methods of Glutaraldehyde (GA), including addition to the solution, vapor exposure, and immersion, were studied by different in-vitro analyses to find the best GA cross-linker concentration and cross-linking method. Scanning electron microscopy showed homogeneous microstructures in all samples. Fourier transform infrared spectrophotometry revealed cross-linking reactions in all samples. Swelling ratio and biodegradation ratio was reduced by increasing cross-linking concentration and exposure time. Nonetheless, higher cross-linker concentration and exposure time improved mechanical properties, while it seems the cross-linking exposure time had more effect than concentration. Accordingly, GA (1 wt%) cross-linked scaffold with solution addition method showed suitable performance with 39.3° contact angle, 1.45±0.05 MPa compressive strength, 22.31±1.3 (%) swelling ratio, and 26.33±4.47 (%) biodegradation ratio. In-vitro experiments indicated cells were spread all over the scaffolds with higher than 80 (%) cell viability in all time points. The expression of alkaline phosphatase (ALP) and osteo-related genes (osteocalcin and related transcription factor 2) were improved during 14 days of cell incubation and showed the high capacity of the scaffold support in mineralization and osto-differentiation. Therefore GA (1 wt% ) cross-linked scaffold with solution addition was introduced as the best candidate for bone repair and further studies.

Encryption is very important to protect sensitive data, especially images, from any illegal access and infringement. This research is presented to provide an image encryption optimization method for communication based on image security. This method uses the grasshopper optimization algorithm to perform optimal encryption and irregular logical mapping. Initially, this approach creates multiple encrypted images and a chaotic map, in which the session key for the initial conditions of the map depends on a simple suspended image. After that, the encrypted images work as an initial and particles set for optimization through the grasshopper optimization algorithm. The optimized encoded image with the correlation coefficient of the continuous pixels is expressed as a function of proportion. The results from Matlab simulation of the proposed encoding method show that the encrypted images are the same, and the adjacent pixels are highly correlated with other outstanding encoding rows, such as planar histogram entropy and effective pixel rate of change average correction strength.

Considering soil layering is a crucial and effective issue in investigating the seismicity of structures. However, previous studies have not examined the presence of a rock layer in soft soil. So; in the present paper, the effect of the rock layer in soft soil on the forces and displacements created in the low-and mid-rise steel moment frame was investigated. Thus, several numerical calculations were performed on 12 different sizes of rock layers at three different depths. Finite element models were analyzed using ABAQUS Software and considering the interaction of structure and soil. Results of the studies show that the value of force and displacement depends on the frequency of the structure, the frequency of the soil-structure system, dominant earthquake frequency, the rock weight, and the stiffness of the structure. Two new parameters are defined that have a linear relationship with force and displacement. Results show that the thickness and length of the rock layer affect the value of force and displacement. Also, the presence of a rock layer in the soil may not be reliable and may increase the shear force by up to 27%, the axial force by up to 10%, and the moment by up to 19%. The effect of the presence of a rock layer on the displacement is more than on the force and increases the lateral displacement by up to 31% and the relative vertical displacement of the foundation by up to 59%.

The problem of solar radiation intermittency can significantly affect the thermal performance of solar air heaters (SAHs). The efficient solution for this problem is utilizing thermal storage to store the thermal energy and using it again in off sunshine hours. The present study analyzed the thermal performance of two configurations of counterflow double pass solar air heater. The first configuration included a conventional flat plate solar absorber, while the second configuration involved tubular capsules that are filled with water as a sensible thermal storage material. The tubular capsules have been installed longitudinally in parallel to the direction of airflow. The study involved numerical and experimental parts. The results showed a remarkable enhancement in useful energy production when using the tubular capsules. Moreover, the SAH with tubular capsules can produce useful energy for a longer time due to the presence of the thermal storage material within capsules. It is found that the total useful energy in the case of tubular capsules is about 4082, 4295.3, 4426, 4584, and 4693 (W) at a mass flow rate of 0.03, 0.025, 0.02, 0.015, and 0.01 (kg/s) respectively, with an increment of 39.1, 51.2, 59.4, 74.8, and 89.6% respectively as compared with the flat-plate absorber. In addition, the average thermo-hydraulic efficiency in the case of tubular capsules are higher than those values which are achieved in flat plate case by about 9.3, 15, 19.6, 28.2, and 40% at a mass flow rate of 0.03, 0.025, 0.02, 0.015, and 0.01 kg/s respectively.

The experimental program of this study aims to investigate the tensile behaviour of geopolymer concrete reinforced with steel fiber and made of recycled materials. The primary ingredients of the steel fiber reinforced geopolymer concrete in this study were waste materials. The recycled steel fiber was extracted from tires and chopped into tiny fibers with an average length of 20 mm and an average diameter of 0.7 mm. The fly ash-based geopolymer concrete in this study consisted of coarse aggregate, which was crushed recycled concrete. Also, the fine aggregate was crushed waste glass. In addition to the compressive strength, tensile test procedures such as splitting tensile strength, double punch tensile strength, and flexural tensile strength were all investigated in this study. Recycled steel fiber was compared to a new and hybrid steel fiber (50% new + 50% recycled) with three different volumetric percentages of steel fiber (0.5%, 1.0%, and 1.5%). The new steel fiber geopolymer concrete mix with 1.5% of steel fiber showed the highest test results among other mixes. This conduct could be explained as the new steel fiber having a uniform, straight shape with hooked ends, increasing the anchorage between the fly ash binder and the steel fiber. In addition, the recycled steel fiber was contained some rubber crumbs that could be another reason that negatively affected the tensile properties of the geopolymer concrete.

In February 2018, the Indonesian government suspended all big-scale elevated construction projects underway in Indonesia for several months to conduct a thorough investigation. The temporary suspension was triggered because of the prevalent construction accidents, most of which were due to construction failures. Previous studies stated that companies should implement a quality culture to carry out quality management properly. This study aims to measure the maturity level of the quality culture of state-owned, private, and foreign construction companies and compare them using gap analysis. In order to do so, this study has developed a measurement instrument adapted for construction companies based on previous studies, expert judgment, and input from respondents. The results showed that the maturity level of state-owned, foreign, and private construction companies in Indonesia were 64%, 70%, and 53% of the expected condition, respectively. In addition, this study observed eight priority indicators to have a significant relationship with construction failure, whose maturity level needs to be improved to reduce the construction failure rate. Those priority indicators included Inspiration & Motivation, Horizontal Alignment, Progress Monitoring, Feedback from Costumer, Staff Empowerment, Attitude to Quality Improvement, Attitude to Staff, and Training Provision.

This research builds a decision-based optimization model to evaluate and decide on the methods of technology transfer in the auto-battery industry under uncertainty. This research is conducted based on the needs of the country's battery industry and shows the impact of technology transfer on world-class manufacturing. At first, the effective indices in the assessment of a technology transfer method are singled out through reviewing the literature and the experts' judgment. The sample population in this research consists of experts from eight auto-battery manufacturing companies. Then, each of the approved indices is assessed via the best-worst method, and in continuation, the technology transfer methods are evaluated and prioritized using an MOORA method as multi-criteria decision-making under uncertainty. The gray theory is also used to deal with uncertainty. According to the results obtained from the best-worst method, the five significant indices (i.e., improving style management, business strategy, cost-effectiveness, how to communicate with the organization, and competitiveness) are considered to select the technology transfer methods in the auto-battery production industry. Finally, to implement the proposed framework in the state auto-battery manufacturing industries, a dual-purpose mathematical model is introduced for optimized world-class technology transfer methods. To solve the proposed model, the developed ε-constraint method is used. Finally, based on the results of the proposed method, the transfer method of joint investment is recognized as the most suitable technique for technology transfer in this industry.

This paper presents a pulsed-power generator that can produce a high voltage bipolar pulse from a relatively low-voltage input source, based on the switched-capacitor concept. The circuit boosts the input voltage by storing energy in several capacitors in a predefined pattern and simultaneously releasing it to the load. It is worth noting that the structure can short-circuit its output terminal while charging the capacitors without using any switches across the load. This topology is mainly suitable for applications requiring a high voltage pulse and only having access to low voltage input sources. Moreover, thee structure can generate a combination of wide and narrow pulses by alteranting its output voltage between two different values. Precise calculation and employment of capacitors ensure that the structure can properly generate the intended output pulses with an acceptable ever-so-slight voltage drop. Finally, MATLAB Simulink was used to evaluate the circuit’s operation, and experimental tests were conducted on a laboratory setup, where the results confirmed the proper performance of the circuit.