Showing papers in "International Journal of Engineering - Transactions C: Aspects in 2023"

Improving the Position Accuracy of Rover Receiver using Differential Positioning in Indian Regional Navigation Satellite System

Abstract: Navigation with Indian Constellation (NavIC) is the Indian Regional Navigation Satellite System (IRNSS) developed by Indian Space Research Organization (ISRO) to provide the position and navigation services for Indian region. NavIC or IRNSS is individual satellite constellation which has seven satellites covering the Indian subcontinent. Accuracy of NavIC standalone is insufficient in certain applications such as civil aviation. To improve the position accuracy performance of NavIC system, differential positioning technique is utilized. In this paper, differential positioning is carried out, considering two IGS (IRNSS-GPS-SBAS) receivers (one as reference station and the other as rover), which are capable of receiving IRNSS signals from 7 satellites, GPS signals from 12 satellites, SBAS signals from 2 satellites. Here, NavIC constellation alone is considered for the analysis. The differential positioning is carried out using the pseudorange measurements on L5 (1176.45 MHz), S1 (2492.028 MHz) and dual (L5 and S1 both) and accuracies are compared in terms of the statistical parameters Circular Error Probability (CEP), Distance Root Mean Square (DRMS), 2DRMS (twice the DRMS). The improvement in the horizontal accuracy (2DRMS) of the rover using pseudorange measurements on L5 is observed to be 78.81%, on S1 it is 69.14 % and using dual frequency (L5 and S1 both) it is 80.73% when compared to NavIC standalone.

Electrolyte Temperature Dependency of Electrodeposited Nickel in Sulfate Solution on the Hardness and Corrosion Behaviors

Abstract: The hardness and corrosion resistance of nickel (Ni) deposit on a substrate could be reached by controlling electrolyte temperature during deposition. In this research, the electrodeposition of Ni at various temperatures of electrolytes was performed. Electrodeposited Ni films using an optical digital camera, X-ray diffraction (XRD), scanning electron microscope with energy-dispersive x-ray spectroscopy (SEM-EDS), microhardness test, and potentiostat were investigated. The bright deposit occurred at 25 °C; an increase in the temperature to 40 °C leads to a change of color into semi-bright. Shifting to a higher temperature would increase the deposition rate, cathodic current efficiency, grain size, and oxygen content. The X-ray reflections in the planes (111), (200), and (220) correspond to as the Ni phase with a face center cubic (FCC) crystal structure. Decreasing crystallite size and micro-strain promoted to reach high hardness. Increasing the corrosion current density implies decreasing polarization resistance. The sample at the lowest electrolyte temperature has a better hardness, and the sample formed at 25 °C sulfate solution had less corrosion rate.

Numerical Analysis on Flow Characteristics of Gas-liquid Two-phase Flow in a Vertical Pipe with Downward Stream

Abstract: Through this paper, a 3D simulation together with experimental observation was conducted to study two-phase flow in a vertical tube. OpenFOAM software was employed to analyze air and water. Main flow stream was downward which was considered to be within a vertical pipe of 10 mm in diameter. Study included two inputs for flows: upper input for water and side input for air. Several states with various mass fluxes for both water and air were studied. Based on physics of the issue, numerical simulation was considered to be time-dependent. Obtained results showed that when air velocity occupied lower values, air momentum cannot overcome water momentum leading in small slugs. When airflow velocity was more than water flow rate, it dominated water flow and consequently could affect mainstream direction. Also, velocity graphs on centerline represented that going forward in time, velocity magnitude experiences a significant value of fluctuations and large oscillations occur next to outlet. Comparing experimental and numerical results, approximately 9% differences can be found which showed suitable agreement. Results showed that at initial steps, void fraction faces a significant jump in values. Intensity of this change in void fraction values was higher in lower water velocity. Indeed, by increment of water velocity, inertial forces associated with liquid phase find a dominant role in overall hydrodynamics of the gas-liquid flow. Also, it is obvious that flowing manner in cases 1, 2, and 3 are similar but after case 4, flow pattern varies. These changes are more considerable in cases 5 and 6.

Potential Use of Fly Ash for Developing Angular-shaped Aggregate

Abstract: The prices of aggregate are increasing in India due to the massive demand for natural aggregate for infrastructure development. An attempt has been made to check the feasibility of the past developed technique for developing angular-shaped light-weight fly ash coarse aggregate from three different types of fly ashes. In this study, the effects of binder content, water content and hot water bath curing temperature on the compressive strength of blocks, as well as the impact value of prepared aggregate for fly ash-binder mixes were investigated. A relationship between impact value and compressive strength has also been suggested to predict the impact value of fly ash aggregate based on the compressive strength of block. For making angular-shaped fly ash aggregate, it was found that the fly ash with CaO content of 0.71%-3.85% requires higher binder content and curing temperature than that required for fly ash with CaO content of 10.45%. The resulting lightweight aggregates from three fly ashes have a compacted structure and angular shape for good interlocking. The results of mechanical properties test showed that the aggregate also meets the criteria of Indian code specifications for structural concrete aggregate.

Evaluating Finn-Byrne Model in Liquefaction Analysis of Quay Wall and Cantilevered Retaining Wall Models

Abstract: Two centrifuge tests on a quay wall and a cantilevered retaining wall with saturated granular backfills were simulated using Finn-Byrne model. Capabilities of Finn-Byrne model in liquefaction analysis of the quay wall and the cantilevered retaining wall were evaluated. The quay wall model subjected to a horizontal acceleration time history and the cantilevered retaining wall model subjected to a horizontal and a vertical time history. The constitutive model is a linear elastic – perfectly plastic model. Hooke’s elasticity and Mohr-coulomb criterion for the yield surface were assumed for the backfill material behavior. The excess porewater pressure generation, acceleration, wall lateral displacement, lateral earth pressures, deformation pattern, and backfill settlements were monitored and compared with centrifuge tests’ results. The results showed that the adopted model is suitable for stability and displacement analyses of the quay walls and cantilevered retaining walls. However, a care should be taken when assessing the backfill settlements and dynamic earth pressure behind the wall stem. The rest of the results showed a good agreement with the centrifuge tests’ results.

A Dynamic Model for Laminated Piezoelectric Microbeam

Abstract: Piezoelectric beams are widely used in micro-electromechanical systems. At the microscale, the influence of the size effect on a piezoelectric beam cannot be ignored. In this paper, higher-order elasticity theories are considered to predict the behaviors of piezoelectric micro-structures and a size-dependent dynamic model of a laminated piezoelectric microbeam is established. The governing equations for the laminated piezoelectric microbeam are derived using the variational principle. The natural frequencies of piezoelectric microbeams are obtained by size-dependent dynamic models. The results reveal that the size effect can enhance the structural stiffness at the microscale. The natural frequency obtained by using the classical model is smaller than that obtained using the size-dependent model. Compared with the modified couple stress model, the modified couple stress model underestimates the size-dependent response. Thus, the modified couple stress model is a simplification of the modified strain gradient model. The influence of beam thickness on the natural frequency is also discussed. With increasing the thickness, the natural frequency of the size-dependent models gradually approaches the result of the classical model. If the value of h/l is greater than 15, the influence of the size effect can be neglected. Additionally, the relative thickness can influence the natural frequency, and if the relative thickness is greater than 5 or less than −5, the bilayer beam can be simplified to a single-layer beam.

Comparative Analysis of Web Hosting Server Performance

Abstract: This research discusses the comparison performance of different hosting servers. The hosting server that is used as a comparison consists of four types. Namely, Indonesian shared hosting servers, foreign shared hosting servers, Indonesian virtual private servers, and foreign virtual private servers. The parameters tested in this study are load time, domain name system, connection, and secure socket layer. The tools used for testing the performance comparison of the hosting server are Dotcom-Tools, Pingdom.com, Webpage Test, and sitespeed. The results of this comparison can be an input for potential users who have plans to online their applications using a hosting server. The total value of web server hosting Indonesian shared hosting servers (SH I) is 28.975 milliseconds (ms), foreign shared hosting servers (SH LN) are 8.267 ms, Indonesian virtual private servers (VPS I) are 14.195 ms, Foreign virtual private servers (VPS LN) are 11.835 ms. This research concludes that foreign shared hosting servers (SH LN) are the best web hosting servers because, on some of the parameters tested, this server has the best value because it gets the lowest value with 8.267 ms.

Evaluation of lightweight Concrete Core Test Including Steel Bars

Abstract: In many steel reinforced concrete members, steel bars are not avoidable during concrete core drilling and the presence of these steel bars have a direct impact on the results of this test. This study aims to examine the effect of steel bars presence on the test results of recycled aggregate lightweight concrete (LWC) cores. For the purpose, one lightweight concrete mix was made with a total number of 48 concrete cores were taken from a slab having the dimensions of 1 m width, 1.5 m length and 0.15m thickness. Each core has the dimensions of 90 mm in diameter and 150 mm in height. Three different sizes of steel bars (12, 16 and 20 mm) were used in six different locations (25, 45 and 65 mm) from the base of the core and (15 and 30 mm) from the center line of the core. A recycled crashed clay brick (CCB) was used as an alternative to the coarse aggregate. Compare to the density of the normal concrete (2400 kg/m3), the LWC was able to achieve nearly 20% reduction of the total weight by fully replacing of normal aggregate with CCB. It has been found that the presence of the steel increases the compressive strength of the LWC cores. This effect is more noticeable when the location of the steel bar is near to the mid-height or the centerline of the concrete core. Also, the influence of the steel bar diameter has increased by increasing the size of the steel bar.

Synthesis of Hard Layer by Titanium Addition During Welding Process and Quenched Directly

Abstract: Enhance the surface hardness of materials usually conducted through a hardfacing technique. Hardfacing is popular, whereby materials with better properties are deposited over cheaper bulk material. This work fabricated hard layers by adding titanium (Ti) wire during the welding process. This research used low-carbon steel as the base material, wire optime Ti grade 1 for Ti addition, and an HV 600 electrode with a diameter of 3.2 mm for filler metal. A single-layer weld was conducted with SMAW (positive polarity and 90 A). The samples were directly quenched in a different solution after welding. The properties of the weld layer were examined phase, structure, microstructure, macrostructure, and hardness using optical emission spectroscopy (OES), x-ray diffraction (XRD), an optical microscope, a digital camera, and a hardness device, respectively. Adding titanium (Ti) to the weld layer and quenching the samples after welding in the solution enhances the hardness. This phenomenon is attributed to different phase compositions, oxides, and microstructures. A fine dispersion of small particles and oxide amount is important in increasing hardness. There is no cracking in the weld and base metal. In conclusion, samples BNTiO and BNTiM are recommended for lathe-cutting tools.

An Enhanced McCormick Envelopes to Represent Kron's Loss Formula

Abstract: Recently, some researchers have employed the McCormick envelopes method to convexify some NP-hard optimization problems with bilinear terms. However, few publications concentrate on its variants to derive a more tight convex relaxation for practical applications. This paper proposes a new viewpoint on Kron’s loss formula, also known as the B-matrix formula, as an equation having bilinear terms. Relying on the perspective, we transform the loss equation to some linear constraints using an enhanced McCormick relaxation. In the technique, the domain of bilinear variables is divided into some smaller parts to improve the relaxation tightness. Some case studies with different nonconvex terms are considered to verify the effectiveness of the enhanced envelopes for capturing Kron’s loss formula. The findings from the numerical simulations suggest that the proposed approach can represent Kron’s loss equation precisely. Moreover, the method performs more effectively than the other methods available in the literature as it usually converges to more optimal solutions.

Equilibrium of Ammonia (NH3) and Ammonium (NH4+) during Microalgae Harvesting using Electrocoagulation

Abstract: Harvesting microalgae is an important process in gaining biomass while the remaining water is still rich in nutrients. These nutrients, mainly nitrogen and phosphorous, could cause eutrophication of water bodies (rivers, lakes, and oceans) and ecosystem degradation if discharged directly without proper treatment. Electrocoagulation (EC) is one of the harvesting methods and has several advantages: ease of operation, fast harvesting, adaptability, environmental friendliness, and low footprint. However, EC method for harvesting microalgae has the potential in producing ammonia, which is undesirable due to its threat to the environment. The purpose of this study is to establish the equilibrium of ammonium (NH4+) and ammonia (NH3) during Dunaliella salina harvesting. The harvesting was conducted using EC with a variation of 20 volts, 30 min, and 400 rpm. The result shows that the harvesting efficiency can reach 93.72% after 5 min of processing, decreasing the concentration of inorganic nitrogen compounds in total ammonia nitrogen (TAN) to 98.80%.

Viscosity Analysis of Water-based Copper Oxide Nanofluids

Abstract: In this paper, the effects of weight concentration of nanoparticles and temperature on the viscosity of water-based copper oxide nanofluids have been studied experimentally using analysis of variance (ANOVA)-based two-factor three-level (23) factorial design. The results show that a maximum increase of 23.12% in viscosity is observed at 30°C temperature as the weight concentration of nanoparticles increases from 0.03 to 0.3wt.%. Whereas the temperature increases from 30 to 60°C, the viscosity decreases up to 46.19% in the case of 0.3wt.% nanofluid. Temperature is found to be more dominant than the concentration of nanoparticles. The optimum value of viscosity (0.513 mPa.s) is found at concentrations of 0.1wt.% and 60°C temperature with an 18.72% enhancement in viscosity as compared to the base fluid. The experimental and model values of viscosity have been compared with the predictions of the proposed equation for viscosity. The experimentally measured results are found near the proposed results whereas the model underestimates the viscosity in the case of all nanofluids. The maximum underestimation of 25.92 % was observed in the case of 0.3wt.% nanofluid at 60°C temperature.

Application of Ultra-sensitive Pillar-enhanced Quartz Crystal Resonators for Airborne Detection of Nanoparticles: A Theoretical Study

Abstract: Although quartz crystal resonators (QCR) have been used for airborne detection of particles and viruses, they suffer from various limitations, such as low sensitivity compared to other devices. Therefore, it is necessary to develop a new device capable of achieving high sensitivity, which can be used for practical airborne detections. The current study reports a comprehensive parametric theoretical model for analyzing the response of ultra-sensitive pillar-enhanced QCR (QCR-P) for airborne detection of nanoparticles. The electromechanical model comprised an equivalent circuit integrated with pillars containing nanoparticles. It was shown that pillar height and particle radius play a critical role in the response of QCR-P devices. The study revealed that selecting the optimal pillar height can lead to a significant frequency shift depending on the nanoparticle radius and pillar height, while it is independent of particle mass density. These results underscore the potential of utilizing pillars to substantially enhance the sensitivity of conventional QCR up to 140 times in the airborne detection of nanoparticles. These findings can be utilized to design optimum pillar heights to achieve maximum sensitivity in the airborne detection of nanoparticles and proteins, thereby enabling the adoption of ultra-sensitive pillar-enhanced quartz crystal resonators for practical airborne applications.

A Novel Hybrid Model for Technology Strategy Formulating in High-tech Industries under Uncertainty: A Case Study

Abstract: Globalization and increased virtual communication have posed many challenges to high-tech companies; hence, such companies are sparing efforts to detect the best technologies in this field to solve new and emerging challenges addressing traffic load, communication system security, and infrastructure optimization. Telecommunications companies deal with a highly dynamic and uncertain environment, where their relevant technologies are changing and developing at an increasing speed. Regarding such an environment in telecommunications companies, the present study aimed to present an efficient model for formulating technology strategies for these companies. The proposed model is a hybrid method of attractiveness-capability matrix and, multi-criteria decision-making approaches in an uncertain and dynamic environment. The model provides the attractiveness-capability evaluation factors and criteria regarding the requirements of dynamic and uncertain environments in these companies. This approach provides a more accurate picture of the rapidly changing technologies in formulating technology strategy. The model also used the fuzzy TOPSIS to control the uncertainty aroused by widespread emerging technologies in such organizations. The proposed model is implemented concerning the requirements of the Mobile Communications Company of Iran (MCI), and its results are discussed in detail.

New Approach of Deployment of the Multi-static Radars Based on an Aperture Angle and the Probability of False Alarm

Abstract: 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.

Human Disease Prediction using Machine Learning Techniques and Real-life Parameters

Abstract: Disease prediction of a human means predicting the probability of a patient’s disease after examining the combinations of the patient’s symptoms. Monitoring a patient's condition and health information at the initial examination can help doctors to treat a patient's condition effectively. This analysis in the medical industry would lead to a streamlined and expedited treatment of patients. The previous researchers have primarily emphasized machine learning models mainly Support Vector Machine (SVM), K-nearest neighbors (KNN), and RUSboost for the detection of diseases with the symptoms as parameters. However, the data used by the prior researchers for training the model is not transformed and the model is completely dependent on the symptoms, while their accuracy is poor. Nevertheless, there is a need to design a modified model for better accuracy and early prediction of human disease. The proposed model has improved the efficacy and accuracy model, by resolving the issue of the earlier researcher’s models. The proposed model is using the medical dataset from Kaggle and transforms the data by assigning the weights based on their rarity. This dataset is then trained using a combination of machine learning algorithms: Random Forest, Long Short-Term Memory (LSTM), and SVM. Parallel to this, the history of the patient can be analyzed using LSTM Algorithm. SVM is then used to conclude, the possible disease. The proposed model has achieved better accuracy and reliability as compared to state-of-the-art methods. The proposed model is useful to contribute towards development in the automation of the healthcare industries.

Application of a Novel Optimization Algorithm in Design of Lead Rubber Bearing Isolation Systems for Seismic Rehabilitation of Building Structures

Abstract: Various mechanical and geometrical parameters have different effects on the isolation system's performance. Thus, a sensitivity study of the isolated structures' behavior is an essential matter. In this regard, the isolation systems should be designed using optimization approaches to consider the effects of the different factors. In this study, the optimal design of the lead rubber bearing (LRB) seismic isolation was conducted by considering mass irregularity and near-fault seismic excitation effects. Also, sensitivity analysis of the behavior of the considered isolated buildings was implemented concerning the mechanical parameters of the LRB system. A nonlinear time history dynamic analysis was used here, and the design optimization of the LRB isolator was programmed using the newly introduced grasshopper optimization algorithm (GOA). The main purpose was to investigate the ability of the GOA to optimize the design parameters of the LRB-isolated frames. The results proved the desirable ability of the GOA to solve optimal design problems for isolation systems. Also, the sensitivity analysis of the seismic behavior of LRB base-isolated structures showed that the yield base shear index had the most important effects. Also, the mass irregularity parameter showed a negligible influence.

Growth Media Optimization for Production of Alkaline Protease from Industrial Wastewater using Bacillus subtilis PTCC 1254

Abstract: Alkaline proteases are widely used in industrial processes due to their high pH tolerance and thermal stability. In present work, the protease producing ability of Bacillus strains (Bacillus subtilis PTCC 1254, B. subtilis PTCC 1156 and B. subtilis PTCC 1715) was studied. B. subtilis PTCC 1254 showed the highest proteolytic activity and therefore, the strain was selected as the biological agent in the submerged fermentation. Cell growth kinetic model was investigated using Malthus and Logistic equations, which were relatively well fitted to the experimental data. The maximum specific growth rate for Malthus and Logistic models were 0.187 and 0.377 h-1, respectively. The optimum culture conditions were defined as follows: pH 9, temperature 37°C, fermentation time 72 h, agitation speed 150 rpm and 4% inoculum with medium contained 1 g/l CaCl2, 0.6 g/l K2HPO4, 1 g/l KH2PO4, 0.2 g/l MgSO4.7H2O, 2 g/l sugarcane bagasse and 4 g/l corn bran as carbon and nitrogen sources. A 25% v/v industrial wastewater containing starchy waste was used as main substrate. Under optimum conditions, maximum alkaline protease activity of 117.43 U/ml was achieved. Also, the obtained protease was able to remove blood stain from cotton fabric and hydrolyze gelatin of X-ray film. Thus, this protease showed potential applications in detergent and photographic industries.

Standards for Selection of Surfactant Compositions used in Completion and Stimulation Fluids

Abstract: 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.

Numerical Modeling of Sediment-flow around Obstacle Inspired by Marine Sponges: Considering Body Configurations

Abstract: Coral reefs are exposed to extinction due to the sediment blocking through coral colonies. In this condition, there is no practical solution that originates from nature. Among all aquatic animals, marine tubular sponges have marvelous mechanisms. These natural creatures can inspire the design of a device for managing sediment-flow hydrodynamics. They suck flow from body perforation and pump water and undigested materials from the top outlet. Therefore, coinciding with receiving nutrients, the flow becomes circulated. This may help the momentum transfer through the coral colonies. In the current study, a synthetic sponge by motivating the tubular sponges was designed. Synthetic sponges’ suction/pumping discharge was constant at 150 L/h. They have a body diameter of 8 and 15 cm and a height of 20 cm. The perforation area distribution changes to understand how it may influence sediment-flow hydrodynamics. The numerical modeling based on Reynolds Averaged Navier Stokes (RANS) equations and image processing technique (surface LIC) were deployed to determine the vortical flow patterns. Results confirmed that choosing the best body perforation configuration and area distribution can generate the dipole vortex. In this condition, a tornado combines with dipole and erodes the sediments to ≈ 30% near the bed. Moreover, the sediment concentration reduces to ≈ 20% in the water column at X/D =1. In this condition, it can be observed that the emergence of specific vorticities and re-circulations develops the suspension of particles. Therefore, the synthetic sponge with precise design can be practical for enhancing the momentum transferring and preventing pollutant blockage among coral colonies.

Effect of Aging Treatment on Microstructure and Mechanical Properties of Al0.7CoCrFeNi High Entropy Alloy

Abstract: In this study, the effects of aging times and temperatures on the microstructure, hardness and compression strength of Al0.7CoCrFeNi high entropy alloy have been investigated. The alloy was cast in a vacuum induction melting furnace, homogenized at 1250 ˚C for 6 h; then aged at 700 to 1000˚C for 2-8 h. The as-cast structure is dendritic and includes FCC(A1) and BCC(A2, B2) phases with the hardness of 497 HV. During ageing, B2 precipitates at the grain boundaries at 700˚C and the hardness increases about 7%. The ratio of BCC to FCC phases on the basis of XRD in as-cast alloy is approximately equal which is increased by ageing at 700˚C. At 800˚C, the formation of a destructive and hard phase of σ cause to increases the hardness to 543 HV and the ratio of (A2+B2)/A1 has decreased. At 1000 ˚C, the ratio of (A2+ B2)/A1 increases, and the peak intensity of σ decreases, so that the hardness value decreases to 385 HV. The results of hot deformation test showed that the alloy at the strain rate of 10-3 s-1 and temperatures of 800, 900, 1000 and 1100˚C has a yield strength of 306, 179, 91 and 50 MPa, respectively.

Experimental Investigation of the Effects of using Waste Rubber Ash on Mechanical Properties of Plain Concrete

Abstract: In this study, the effects of using rubber ash on the mechanical properties of plain concrete were experimentally investigated. The main purpose of this study was to determine the proper fraction of rubber ash to be utilized in concrete by investigating the mechanical properties of concrete such as elasticity modulus, compressive strength, tensile strength, bending strength, and fresh concrete slump. Four different fractions of rubber ash (2.5, 5, 7.5 and 10% of cement weight) were added to the concrete mixture. Based on the results achieved from the tests conducted on the specimens, it could be deduced that adding rubber ash to concrete considerably increased compressive and bending strength and reduced the slump flow. It also increased tensile strength and elasticity modulus at a lower level.

Design and Simulation of a Novel Hetero-junction Bipolar Transistor with Gate-Controlled Current Gain

Abstract: A new structure for SiGe Hetero-junction Bipolar transistor (HBT) is designed and simulated using Silvaco simulator. The considered extra terminal gives the ability to control the transistor's current gain. By applying voltage to the gate terminal, the base effective width would be controlled. Decrement of the Base width yields to the carrier recombination rate reduction, let the emitted electrons to have higher chance to reach the collector. Considering extra terminal have two approaches. One is to improve the current gain of the transistor by applying a constant voltage to the gate and the other is to modify the characteristics of the transistor in such a way that the current gain became optimized. The current gain of the transistor without any gate voltage is about 50V, which increases to 750 for high and 50,000 for low collector currents with the gate voltage variation consideration. In addition, our final proposed gate-controlled HBT with a large gate over the base and collector has the breakdown voltage of 8V and the cut-off frequency of about 11 GHz. The maximum FoM of 1200 is achieved using the proposed structure.

Variations of Organic Loading Rate on Tofu Wastewater Degradation using Upflow Anaerobic Sludge Blanket Reactor by Modified Stover-Kincannon Model

Abstract: This research aims to examine the varians of organic loading rate (OLR) on degradation of tofu wastewater using the hybrid upflow anaerobic sludge blanket (hybrid UASB) reactor using the modified kinetic model of Stover Kincannon. This reactor was operated at OLRs variation of 1.5-12 kg COD m-3 d-1 and HRT of 12 - 24 hours for 328 days. Higher COD removal efficiency of 86.41% and biogas production of 7700 mL were achieved at OLR 4.8 kg COD m-3 d-1 and HRT 24 hours on 140 days. Modified Stover-Kincannon model was observed and matched data sets were obtained. The kinetic values of model obtained at HRT variations, the parameters KB and μmax were 3.7, 12.97, 2.42 mgL-1 d-1 and 0.59, 9.41, 0.014 mgL-1 d-1, respectively. This model was a plot of the inverse of the removal rate, versus inverse of the total loading rate resulted in a straight line. It showed that the Stover-Kincannon Model is the rate of substrate removal was affected by the organic load rate (OLR) that flowed into the hybrid UASB reactor.

Experimental Analysis of Square Position on Variable Displacement Electrohydraulic Actuation System by Open Loop Control

Abstract: Electrohydraulic actuation systems offer definative position control and an energy-efficient solution. Such systems are widely used in mobile machinery, robotics, and various stationary systems. Achieving good control of actuator position of the variable displacement electrohydraulic actuation system by an open loop control is the objective of this study. For square position (reference position) control, amplitude is taken as 0.1 m, at 0.05, 0.15 and 0.25 Hertz of frequency. Square position control is accomplished with LabVIEW algorithm through the application of compact RIO controller having input and output module. Appropriate control of voltage supply is obtained, when response position and reference position show appropiate accuracy. A higher Pearson’s correlation coefficient near to 1 and lower the Mean absolute error, Mean deviation of error and standard deviation of error represent the best response position. It is observed that highest value of correlation coefficient achieved at 0.05 Hertz of frequency for response R3. At a lower frequency, square position control is better with higher correlation coefficient and lowest values of errors.

A Hybrid Approach to Sentiment Analysis of Iranian Stock Market User’s Opinions

Abstract: With the significant growth of social media, individuals and organizations are increasingly using public opinion in these media to make their own decisions. The purpose of sentiment analysis is to automatically extract people’s sentiments from those social networks. Social networks related to financial markets, including stock markets, have recently attracted the attention of many individuals and organizations. people in these networks share their opinions and ideas about each share in the form of a post or tweet. In fact, sentiment analysis in this field is the assessment of people’s attitude towards each share. There are different approaches in sentiment analysis, in this article, a hybrid approach is proposed for sentiment analysis. In this way the feature vector used in machine learning is obtained from a lexicon that is automatically extracted from user’s tweets. This lexicon is made by using stock price information related to user’s opinion. Also, by using the next day’s price information of each share, amendments were suggested to this lexicon. Therefore, the lexicon generated for the feature vector was constructed in three ways, and all three methods reported about an 8% improvement over the baseline method in terms of F-score. The baseline method that is considered for this work, is the Persian version of SentiStrength lexicon which is designed for general purpose.

Compaction Quality Control of Coarse-grained Soils Using Dynamic Penetration Test Results through Correlation with Relative Compaction Percentages

Abstract: In this study, in order to control the compaction quality of the coarse-grained soils used in sub-base and base layers of several road construction projects, the dynamic penetration test (DPT) has been conducted on 50 locations using both dynamic penetrometer of light (DPL) and dynamic penetrometer of medium (DPM). First, in order to obtain the results independently from the penetrometer type, the dynamic cone resistance (qd) values were calculated in each location based on hammer blows of both DPL and DPM. Next, the average values of qd obtained by both the penetrometers, were correlated with the percentages of relative compaction (RC) in the same location obtained by performing the sand cone test on location and modified proctor test in laboratory. Accordingly, it was extracted a power correlation between the qd values and RC percentages, with the determination coefficient (R2) of about 0.64. Then, for considering the effect of soil grains size using the median particle size (D50), a more accurate power correlation was obtained which as a result, the R2 value enhanced to 0.89. Furthermore, in order to consider the soil vertical stresses caused by depth of testing as well as obtaining a normalized relationship, the qd values were divided by the vertical stresses and correlated with the RC percentages. Afterwards, regarding the effect of soils grains size and also their gradation properties, this time by using the dimensionless coefficients of uniformity (Cu) and curvature (Cc), it was extracted an other normalized power correlation. The results showed that the R2 value enhanced from about 0.49 to 0.92.

Improving the Accuracy of Brain Tumor Identification in Magnetic Resonanceaging using Super-pixel and Fast Primal Dual Algorithm

Abstract: Brain tumors are one of the most common causes of death that have been widely investigated by scholars in research areas, including care and prevention. Despite various empirical studies on the brain tumor segmentatin, there is still a need for further investigation. This fact is more needed in the automatic methods of brain tumors detection. In the present study, a new method for improving brain tumor segmentation accuracy based on super-pixel and fast primal dual (PD) algorithms has been proposed. The proposed method detects brain tumor tissue in Flair-MRI imaging in BRATS2012 dataset. This method detects the primary borders of tumors using a super-pixel algorithm, and improves brain tumor borders using fast PD in Markov random field optimization. Then, post-processing processes are used to delete white brain areas. Finally, an active contour algorithm was employed to display tumor area. Different experiments were carried on the proposed method and qualitative and quantitative criteria such as dice similarity measure, accuracy and F-measure were used for evaluation. The obtained results showed the efficiency of the proposed method, such that in the accuracy and sensitivity of 86.59 and 88.57% and F1-Measure 86.37 were obtained, respectively.

The Equipment Scheduling and Assignment Problem in the Overhaul Industry

Abstract: In this article, equipment overhaul is considered in a multi-stage flow shop scheduling problem. In this problem, the equipments are disassembled in the first stage, overhaul and repairs are done on the equipment in parallel workshops in the second stage, and the assembly operation is done in parallel workshops in the third stage. Considering a three-stage overhaul with parallel machines in the second and third stages is new in the overhaul industry. The sequence of equipment processing is determined in the first stage, as well as the allocation and sequence of equipment in the second and third stages should be done in such a way that the total completion time of jobs is minimized. Unlike most articles, the sequence of processing jobs is not the same in all stages and changes with the use of decoding. For the next innovation: in order to solve the problem, a new mathematical model is presented. Two new improved algorithms, Genetic Algorithms (GA) and Particle Swarm Optimization (PSO) are presented to solve the problem in large dimensions. By using the shortest processing time (SPT) heuristic, these two algorithm have been improved and Hybrid GA (HGA) and Hybrid PSO (HPSO) algorithms have been presented. In order to achieve better results with the current conditions, the parameters setting is done by one-way analysis of variance (ANOVA). Finally, it is possible to improve the performance of the equipment by applying the discussed issues.

Performance Assessment of Ductile Detailing Code-Based Reinforced Concrete Special Moment Resisting Frames

Abstract: Reinforced concrete (RC) buildings make up the majority of Indian building stocks. Structural elements of these buildings are often designed limited to non-ductile detailing. With a very low building replacement rate, many Indian buildings are vulnerable to earthquakes and pose a significant risk to lives, properties and economic activities. This paper examines the effectiveness of ductile-detailing in mitigating the seismic collapse risk by analyzing the behaviour of a four-storey RC Special Moment Resisting Frame (RC SMRF) using the latest codes of ductile detailing. It also aims to quantify the impact of lateral force resisting system detailing on the performance and cost of RC SMRF buildings and its benefits. The present study emphasizes the effect of ductile detailing on three fundamental aspects of the structure – safety, stability and economy. Two four-storeyed building models – one without ductile detailing and the other with ductile detailing are designed and then analyzed using non-linear static analysis. The results of this study represent the behaviour of ductile-detailed and non-ductile-detailed buildings in terms of pushover curves, and hinge behaviour and identify the mode of final failure. In extension to that, a cost-benefit analysis is done to study the benefits of ductile detailing with the increased cost. The marginal increase in initial cost associated with ductile detailing is significantly outweighed by the resulting savings in the repair and downtime costs during the service life of the building.