Kinetic Spectrophotometric Determination of Trace Amounts of Sulfide

Barzegar, Mohsen,Jabbari, Ali,Esmaeili, Majid Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.9

A method for the determination of trace amount of sulfide based on the addition reaction of sulfide with methyl green at pH 7.5 and $25{\circ}C$ is described. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of the dyestuff at 637 nm by the initial rate and fixed time method. The calibration graph is linear in the range 30-1200 ppb. The theoretical limit of detection was 0.014 ppm. Seven replicate analysis of a sample solution containing 0.70 ppm sulfide gave a relative standard deviation of 1.5%. The interfering effects of various ions on sulfide determination have been reported and procedures for removal of interference have been described. The proposed method was applied successfully to the determination of sulfide in tap and wastewater samples.

Numerical study on the performance of semicircular and rectangular submerged breakwaters

Barzegar, Mohammad,Palaniappan, D. Techno-Press 2020 Ocean systems engineering Vol.10 No.2

A systematic numerical comparative study of the performance of semicircular and rectangular submerged breakwaters interacting with solitary waves is the basis of this paper. To accomplish this task, Nwogu's extended Boussinesq model equations are employed to simulate the interaction of the wave with breakwaters. The finite difference technique has been used to discretize the spatial terms while a fourth-order predictor-corrector method is employed for time discretization in our numerical model. The proposed computational scheme uses a staggered-grid system where the first-order spatial derivatives have been discretized with fourth-order accuracy. For validation purposes, five test cases are considered and numerical results have been successfully compared with the existing analytical and experimental results. The performances of the rectangular and semicircular breakwaters have been examined in terms of the wave reflection, transmission, and dissipation coefficients (RTD coefficients) denoted by K_R, K_T, K_D. The latter coefficient K_D emerges due to the non-energy conserving K_R and K_T. Our computational results and graphical illustrations show that the rectangular breakwater has higher reflection coefficients than semicircular breakwater for a fixed crest height, but as the wave height increases, the two reflection coefficients approach each other. un the other hand, the rectangular breakwater has larger dissipation coefficients compared to that of the semicircular breakwater and the difference between them increases as the height of the crest increases. However, the transmission coefficient for the semicircular breakwater is greater than that of the rectangular breakwater and the difference in their transmission coefficients increases with the crest height. Quantitatively, for rectangular breakwaters the reflection coefficients K_R are 5-15% higher while the diffusion coefficients K_D are 3-23% higher than that for the semicircular breakwaters, respectively. The transmission coefficients K_T for rectangular breakwater shows the better performance up to 2.47% than that for the semicircular breakwaters. Based on our computational results, one may conclude that the rectangular breakwater has a better overall performance than the semicircular breakwater. Although the model equations are non-dissipative, the non-energy conserving transmission and reflection coefficients due to wave-breakwater interactions lead to dissipation type contribution.

Spatial experience based route finding using ontologies

Barzegar, Maryam,Sadeghi-Niaraki, Abolghasem,Shakeri, Maryam Electronics and Telecommunications Research Instit 2020 ETRI Journal Vol.42 No.2

Spatial experiences in route finding, such as the ability of finding low-traffic routes, exert a significant influence on travel time in big cities; therefore, the spatial experiences of seasoned individuals such as taxi drivers in route finding can be useful for improving route-finding algorithms and preventing using routes having considerable traffic. In this regard, a spatial experience-based route-finding algorithm is introduced through ontology in this paper. To this end, different methods of modeling experiences are investigated. Then, a modeling method is chosen for modeling the experiences of drivers for route finding depending on the advantages of ontology, and an ontology based on the taxi drivers' experiences is proposed. This ontology is employed to create an ontology-based route-finding algorithm. The results are compared with those of Google maps in terms of route length and travel time at peak traffic time. According to the results, although the route lengths of route-finding method based on the ontology of drivers' experiences in three cases (from nine cases) are greater than that based on Google maps, the travel times are shorter in most cases, and in some routes, the difference in travel time reaches only 10 minutes.

Investigation of the U-shape submerged breakwater performance by the finite-different scheme

Barzegar, Mohammad Techno-Press 2021 Ocean systems engineering Vol.11 No.1

The submerged U-shape breakwater interaction with the solitary wave is simulated by the Boussinesq equations using the finite-difference scheme. The wave reflection, transmission, and dissipation (RTD) coefficients are used to investigate the U-shape breakwater's performance for different crest width, Lc1, and indent breakwater height, du. The results show that the submerged breakwater performance for a set of U-shape breakwater with the same cross-section area is related to the length of submerged breakwater crest, Lc1, and the distance between the crests, Lc2 (or the height of du). The breakwater has the maximum performance when the crest length is larger, and at the same time, the distance between them increases. Changing the Lc1 and du of the U-shape breakwaters result in a significant change in the RTD coefficients. Comparison of the U-shape breakwater, having the best performance, with the averaged RTD values shows that the transmission coefficients, Kt, has a better performance of up to 4% in comparison to other breakwaters. Also, the reflection coefficients KR and the diffusion coefficients, Kd shows a better performance of about 30% and 55% on average, respectively. However, the model governing equations are non-dissipative. The non-energy conserving of the transmission and reflection coefficients due to wave and breakwater interaction results in dissipation type contribution. The U-shape breakwater with the best performance is compared with the rectangular breakwater with the same cross-section area to investigate the economic advantages of the U-shape breakwater. The transmission coefficients, Kt, of the U-shape breakwater shows a better performance of 5% higher than the rectangular one. The reflection coefficient, KR, is 60% lower for U-shape in comparison to rectangular one; however, the diffusion coefficients, Kd, of U-shape breakwater is 35% higher than the rectangular breakwater. Therefore, we could say that the U-shape breakwater has a better performance than the rectangular one.

Research on Hand Tremors-Free in Active Joint Dental Automation

Ali Barzegar,Farzin Piltan,Abdol Majid Mirshekaran,Alireza Siahbazi,Mahmood Vosoogh,Nasri Sulaiman 보안공학연구지원센터 2015 International Journal of Hybrid Information Techno Vol.8 No.12

This research describes the design and implementation of nonlinear control strategies for three dimensions joint dental robot manipulators whose dynamic or kinematic models are uncertain. This technique describes the development of an adaptive task-space tracking controller for dental robot manipulators with uncertainty in the kinematic and dynamic models. The controller is developed based on the unit quaternion representation so that singularities associated with the otherwise commonly used three parameter representations are avoided. This controller requires the assumption that the manipulator models are nonlinearly parameterizable. However there might be scenarios where the structure of the manipulator dynamic model itself is unknown due to difficulty in modeling. These manipulators do not have rigid joints, hence, they are difficult to model and this leads to significant challenges in developing high-performance control algorithms. In this research to eliminate the hand tremors, PID controller is used and to improve the performance and reduce the steady state error PI based PD fuzzy rule base controller is used.

New Symmetric and Hybrid Multilevel Inverter Topology Employed in Solar Energy Systems

Mostafa Barzegar Kalashani,Daryush Nazarpour 한국전기전자재료학회 2018 Transactions on Electrical and Electronic Material Vol.19 No.4

In this paper, novel symmetric and hybrid topologies have been proposed for single phase multilevel inverter structuresbased on a new basic unit. The proposed topologies can be employed in solar energy systems. The main focus of this paperis to reduce the overall cost as well as to increase the effi ciency of the multilevel inverters. To generate greater number ofvoltage levels, the basic units have been cascaded with each other to make extended topology. Diff erent comparisons such asthe number of power switches and percentage of THD against the number of voltage levels have been drawn to illustrate theadvantages of the proposed topologies. To validate the performance of the proposed topologies, a 20 kW PV arrays basedon fi fteen-level hybrid inverter has been simulated through MATLAB/Simulink software.

Speed Control of Three-Phase Induction Motor Employing a Modular Multilevel Inverter Under Normal and Fault Tolerant Conditions

Mostafa Barzegar Kalashani,Behrouz-Tousi 한국전기전자재료학회 2018 Transactions on Electrical and Electronic Material Vol.19 No.6

Incapability under faulty conditions is one of the most important problems of induction motor drives which are controlledby multilevel inverters. This paper investigates a modular multilevel inverter which is employed as an induction motor drivewith capability of operation under normal and faulty conditions. For this aim, diff erent switching scenarios have been defi nedfor each switch under faulty conditions. In this method, when one of the switches is faulted, the switching scenario is alteredand the motor operates in its normal mode although a percent of output power is lost. One of the most important factors inmultilevel inverter design is the number of the power electronic elements which directly infl uences the cost of the system. From this view point, the presented multilevel inverter structure employs fewer number of power electronic elements in comparisonwith other conventional multilevel inverter topologies. The other advantage of the presented topology is its capabilityto cascade diff erent units which can be used for high power motor applications. To illustrate the effi ciency of the proposedsystem, a closed loop indirect fi eld oriented control method has been applied to the suggested topology. Diff erent scenariosincluding normal and abnormal conditions have been applied to the system. To verify the valid operation of the presentedsystem, a 15 kW three phase induction motor is selected and simulated using MATLAB/Simulink software. According tothe analysis and simulation results, the presented system shows a good performance under various conditions. In addition,good voltage balancing and low total harmonic distortion are the main features of the proposed system.

Nonlinear Model Predictive Control for Self-Driving cars Trajectory Tracking in GNSS-denied environments

Ali Barzegar,Oualid Doukhi,Deok-Jin Lee,Yeon-ho Jo 제어로봇시스템학회 2020 제어로봇시스템학회 국제학술대회 논문집 Vol.2020 No.10

In this paper, a trajectory tracking control problem for a self-driving vehicle is addressed using a nonlinear model predictive controller (NMPC). The solution relies on a direct multiple shooting method for discretizing the simplified differentially flat bicycle model which was used as a prediction plant to reduce the computational cost of NMPC. The solution makes use of the long prediction horizon of the NMPC, which allows safe trajectory tracking and achieving a user-specified goal location by controlling the longitudinal velocity and the steering angle. GNSS-denied navigation algorithm of the vehicle employs Visual Inertial Odometry (VIO) to obtain the position and orientation of car without using GNSS data. Simulation experiments is conducted to show the effectiveness of the system in tracking desired trajectories in high precision with speeds up to 1 m/s.

Quality retention and shelf life extension of fresh beef using Lepidium sativum seed mucilage-based edible coating containing Heracleum lasiopetalum essential oil: an experimental and modeling study

Hassan Barzegar,Behrooz Alizadeh Behbahani,Mohammad Amin Mehrnia 한국식품과학회 2020 Food Science and Biotechnology Vol.29 No.5

The instability and strong flavor or odor ofessential oils (EO) limit their direct incorporation into foodproducts. In this study, the antioxidant and antimicrobialHeracleum lasiopetalum essential oil (HLEO) was added toLepidium sativum seed mucilage (LSSM) solution at fourconcentrations (0, 0.5, 1, and 1.5%) to develop a noveledible coating and expand its food application. HLEOloadedLSSM coating was then used to improve the shelflife and quality of beef as a model food system. The coatedand control beef samples were periodically analyzed forphysicochemical analysis, microbiological, and sensorycharacteristics over a period of 9 days at 4 C. The HLEOenrichedLSSM coating, particularly 1.5% loaded oneresulted in a significant (p\0.05) increase in oxidativeand microbiological stability and overall acceptance of thebeef samples, compared to the control counterpart. HLEOloadedLSSM coating, therefore, provides a promisingalternative to preserve the meat products under coldstorage.

Mitigation of Ammonia Dispersion with Mesh Barrier under Various Atmospheric Stability Conditions

M. Barzegar Gerdroodbary,Mojtaba Mokhtari,Shervin Bishehsari,Keivan Fallah 한국대기환경학회 2016 Asian Journal of Atmospheric Environment (AJAE) Vol.10 No.3

In this study, the effects of the mesh barrier on the free dispersion of ammonia were numerically investigated under different atmospheric conditions. This study presents the detail and flow feature of the dispersion of ammonia through the mesh barrier on various free stream conditions to decline and limit the toxic danger of the ammonia. It is assumed that the dispersion of the ammonia occurred through the leakage in the pipeline. Parametric studies were conducted on the performance of the mesh barrier by using the Reynolds-averaged Navier-Stokes equations with realizable k-ε turbulence model. Numerical simulations of ammonia dispersion in the presence of mesh barrier revealed significant results in a fully turbulent free stream condition. The results clearly show that the flow behavior was found to be a direct result of mesh size and ammonia dispersion is highly influenced by these changes in flow patterns in downstream. In fact, the flow regime becomes laminar as flow passes through mesh barrier. According to the results, the mesh barrier decreased the maximum concentration of the ammonia gas and limited the risk zone (more than 500 ppm) lower than 2 m height. Furthermore, a significant reduction occurs in the slope of the upper boundary of NH3 risk zone distribution at downstream when a mesh barrier is presented. Thus, this device highly restricts the leak distribution of ammonia in the industrial plan.