Large scale green production of ultra-high capacity anode consisting of graphene encapsulated silicon nanoparticles

Kamali, Ali Reza,Kim, Hyun-Kyung,Kim, Kwang-Bum,Vasant Kumar, R.,Fray, Derek J. The Royal Society of Chemistry 2017 Journal of materials chemistry. A, Materials for e Vol.5 No.36

<▼1><P>High quality graphene nanosheets produced in molten salts were found to be capable of wrapping silicon nanoparticles, leading to the fabrication of graphene encapsulated silicon nanoparticles with an excellent stable electrochemical performance as anode material for Li-ion batteries.</P></▼1><▼2><P>Graphite, which is commercially used as anode material in Li-ion batteries, has a low theoretical capacity of 372 mA h g<SUP>−1</SUP>, and therefore should be replaced by an alternative with high capacity and cyclability for the automotive and other applications. The new material should also be capable of being fabricated by energy efficient non-polluting methods at a reasonable cost. This paper reports on the fabrication of a graphene–silicon nanocomposite which meets all these characteristics. High quality graphene was scalably produced by exfoliation of graphite in molten lithium chloride. Graphene nanosheets produced were found to be capable of wrapping silicon nanoparticles injected into the molten salt, leading to the fabrication of graphene encapsulated silicon nanoparticles with a controllable chemical composition. The electrochemical performance of graphene encapsulated silicon nanoparticles was evaluated and compared with that of Si nanoparticles and mechanically blended Si/graphene. The graphene encapsulated silicon nanoparticles exhibited an excellent stable electrochemical lithiation/delithiation performance with the capacity value of about 2000 mA h per gram of silicon at a high current density of 0.5 A g<SUP>−1</SUP>. The nanocomposite sample containing 50 wt% Si showed a reversible capacity of 981 mA h g<SUP>−1</SUP> after 260 cycles. By increasing the amount of Si content of the nanocomposite to 91 wt%, the reversible stable capacity increased to 2217 mA h g<SUP>−1</SUP>, demonstrating the capability of the molten salt method to correlate the cost and electrochemical performance of the graphene–silicon nanocomposite product.</P></▼2>

Scalable fabrication of highly conductive 3D graphene by electrochemical exfoliation of graphite in molten NaCl under Ar/H2 atmosphere

Ali Reza Kamali 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.52 No.-

The electrochemical exfoliation of graphite in molten NaCl under an Ar-4%H2 atmosphere was examined,and found to be a possible economic method for the green production of highly crystalline 3D graphenerelated nanostructures in a large scale. The role of hydrogen in the exfoliation process is highlighted. Thegraphene product exhibited a uniform mesoporous structure, high electrical conductivity of 2.1105S m 1 as well as a specific surface area of 232 m2 g 1 and thermal stability in air at temperatures below500 C. The exfoliation rate was estimated to be about 200 g graphene per liter of molten NaCl per day.

An Efficient Modified Immigrant Population Search Algorithm for Optimization over Unconstrained Spaces

Hamid-Reza Kamali,Parisa Shahnazari-Shahrezaei 대한산업공학회 2019 Industrial Engineeering & Management Systems Vol.18 No.1

Immigrant Population Search Algorithm (IPSA) is a combinatorial optimization method that is based on the population of solutions. In this paper, the structure of this algorithm is explained for unconstrained optimization. The steps of the algorithm include initialization, new population group immigration, removal of undesirable population groups and local search. After presenting the steps of the algorithm, a comparison with other meta-heuristic algorithms and their performance is done based on a number of mathematical optimization functions. The result of the comparison and statistical analysis shows that the proposed algorithm has a better performance over other algorithms that have been studied.

Free axial vibration analysis of axially functionally graded thick nanorods using nonlocal Bishop's theory

Reza Nazemnezhad,Kamran Kamali 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.28 No.6

Free axial vibration of axially functionally graded (AFG) nanorods is studied by focusing on the inertia of lateral motions and shear stiffness effects. To this end, Bishop's theory considering the inertia of the lateral motions and shear stiffness effects and the nonlocal theory considering the small scale effect are used. The material properties are assumed to change continuously through the length of the AFG nanorod according to a power-law distribution. Then, nonlocal governing equation of motion and boundary conditions are derived by implementing the Hamilton's principle. The governing equation is solved using the harmonic differential quadrature method (HDQM), After that, the first five axial natural frequencies of the AFG nanorod with clamped-clamped end condition are obtained. In the next step, effects of various parameters like the length of the AFG nanorod, the diameter of the AFG nanorod, material properties, and the nonlocal parameter value on natural frequencies are investigated. Results of the present study can be useful in more accurate design of nano-electro-mechanical systems in which nanotubes are used.

The Effects of the Vestibular Rehabilitation on the Benign Paroxysmal Positional Vertigo Recurrence Rate in Patients with Otolith Dysfunction

Reza Hoseinabadi,Akram Pourbakht,Nasrin Yazdani,Ali Kouhi,Mohammad Kamali,Farzaneh Zamiri Abdollahi,Sadegh Jafarzadeh 대한청각학회 2018 Journal of Audiology & Otology Vol.22 No.4

Background and Objectives: Although repositioning maneuvers have shown remarkable success rate in treatments of benign paroxysmal positional vertigo (BPPV), the high recurrence rate of BPPV has been an important issue. The aims of present study were to examine the effects of otolith dysfunction on BPPV recurrence rate and to describe the effect of vestibular rehabilitation exercises on BPPV recurrence in BPPV patients with concomitant otolith dysfunction. Subjects and Methods: Forty-five BPPV patients included in this study (three groups). Patients in group 1 had no otolith dysfunction and patients in groups 2 and 3 had concomitant otolith dysfunction. Otolith dysfunction was determined with ocular/cervical vestibular evoked myogenic potential (oVEMP and cVEMP) abnormalities. Epley’s maneuver was performed for the patients in all groups but patients in group 3 also received a 2-month vestibular rehabilitation program (habituation and otolith exercises). Results: This study showed that BPPV recurrent rate was significantly higher in patients with otolith dysfunction in comparison to the group 1 (p<0.05). Vestibular rehabilitation resulted in BPPV recurrence rate reduction. Utricular dysfunction showed significant correlation with BPPV recurrence rate. Conclusions:Otolith dysfunction can increase BPPV recurrence rate. Utricular dysfunction in comparison to saccular dysfunction leads to more BPPV recurrence rate. Vestibular rehabilitation program including habituation and otolith exercises may reduce the chance of BPPV recurrence.

Resin Capacity of Technical Woven Fabrics: Pore Volume and Pore Shape Simulation

Hamid Reza Sharafat,Mehdi Kamali Dolatabadi,Ali. A. A. Jeddi 한국섬유공학회 2020 Fibers and polymers Vol.21 No.11

Nowadays, technical woven fabrics are broadly utilized as reinforcement of composites. Resin capacity of wovenfabric is one of the main challenges in laminate fabrication. Resin diffusion during fabrication of the composite is extremelydepended on fabric micro-morphology. The geometry of weave unit cell and its pore are fundamental factors in evaluatingresin capacity and resin diffusion within fabrics. The main attempt of this study was obtaining an approach to evaluate resincapacity of a woven fabric via simulating pore shape and pore volume. For this purpose, four basic unit cells for all kind ofweaves were simulated with the two shapes of tow cross-section: lens and racetrack. Afterwards, 3D shape and volume oftheir pores were simulated using this approach. The proposed approach is established on the base of initial data of fabric suchas tow setts, tow titers, planar density and thickness of a technical fabric. To assess the simulation, three types of wovenfabrics namely, plain, twill and satin were impregnated by epoxy resin using vacuum infusion process. The volume fractionsof the matrix and fibers of real composites were compared with simulated ones. It was demonstrated that the approach withracetrack assumption led to high degree of convergence with experimental results. The maximum relative error of pioneeredmethod to evaluate volume of the pore in this condition exceeded up to 1.43 %. Suitable correlation between volumefractions of the pore and void was observed in experimental data. It is experimentally demonstrated that the void volumefraction of composite will be increased with decrease of pore volume due to difficulty of wetting. In this paper, it is illustratedthat the resin capacity of a woven fabric is a function of vacuum level in vacuum infusion process. For instance, resincapacity of a certain plain fabric could be reduced up to 10 % under 60 kPa (0.6 bar) of vacuum in contrast with steady stateof fabric at room atmosphere.

Horizontal Localization in Simulated Unilateral Hearing Loss

Anvarsamarein Parisa,Nazeri Ahmad Reza,Sameni Seyyed Jalal,Kamali Mohammad,Zarrin Koob Homa 대한청각학회 2018 Journal of Audiology & Otology Vol.22 No.1

Background and Objectives: The ability to localize a sound source is one of the binauralhearing benefits in a horizontal plane based on interaural time difference and interaural intensitydifference. Unilateral or bilateral asymmetric hearing loss will affect binaural hearing and leadto sound locating errors. In this cross sectional analytical descriptive study, the localization errorwas investigated when participants turned their heads to the sound source with closedeyes and after simulating unilateral hearing loss by placing earplugs inside the right ear canal. Subjects and Methods: This cross sectional analytical descriptive study was carried out on30 right-handed adults, 22 female and 8 male (average: 25 years, standard deviation: 3.16). They were selected with the available random access method. Horizontal localization wasevaluated with five speakers located at 0, ±30, and ±60 degree azimuths at a 1-meter distancefrom the examinee. Narrow-band noise signals were delivered at 35 dB SL in two “withoutearplug” and “with earplug” situations and the results were compared. The study was performedbetween September and December 2016 in Tehran, Iran. Results: Significantdifferences were observed in localization errors between the “with earplug” and “without earplug”situations. The localization differences were greater for left-side speakers (-30 and -60degrees) compared with right-side speakers (+30 and +60 degrees). The differences weremore apparent at 4,000 and 6,000 Hz, which confirmed the effect of unilateral simulatedhearing loss on interaural latency differences. Conclusions: Simulating hearing loss by usingan earplug in one ear (right) increased localization errors at all frequencies. The errorsincreased at higher frequencies.

Size dependence on reduction kinetic of iron based Fischer–Tropsch catalyst

Ali Nakhaei Pour,Mohammad Reza Housaindokht,Ensieh Ganji Babakhani,Mohammad Irani,Seyed Mehdi Kamali Shahri 한국공업화학회 2011 Journal of Industrial and Engineering Chemistry Vol.17 No.3

Catalyst structure has a significant influence on its kinetic behavior. In this work, effect of nanoparticle size on reduction kinetics of iron FTS catalyst [0] has been studied. Fe/Cu/La catalysts were prepared via bulk precipitation and microemulsion methods to produce a series of iron oxides with different particle size. In microemulsion method, the catalyst particle size was changed with type of surfactant such as SDS, Triton X-100, and SDBS. Size dependence on reduction rate constant (kr) was evaluated using the formation and growth of nuclei model (3D). The results showed that when the catalyst particle size increased, the reduction rate of iron catalyst decreased. A value of 3.11 nm and 0.53 h1were obtained for h parameter and size independent part of reduction rate constant (k1), which are consistent with the values reported in literatures.

Practical Explicit Model Predictive Control for a Class of Noise-embedded Chaotic Hybrid Systems

Seyyed Mostafa Tabatabaei,Sara Kamali,Mohammad Reza Jahed Motlagh,Mojtaba Barkhordari Yazdi 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.4

Controlling a class of chaotic hybrid systems in the presence of noise is investigated in this paper. Toreach this goal, an explicit model predictive control (eMPC) in combination with nonlinear estimators is employed. Using the eMPC method, all the computations of the common MPC approach are moved off-line. Therefore, theoff-line control law makes it easier to be implemented in comparison with the on-line approach, especially forcomplex systems like the chaotic ones. In order to verify the proposed control structure practically, an op-ampbased Chua’s chaotic circuit is designed. The white Gaussian noise is considered in this circuit. Therefore, thenonlinear estimators –extended and unscented Kalman filter (EKF and UKF)– are utilized to estimate signals fromthe noise-embedded chaotic system. Performance of these estimators for this experimental setup is compared inboth open-loop and closed-loop systems. The experimental results demonstrate the effectiveness of the eMPCapproach as well as the nonlinear estimators for chaos control in the presence of noise.

Dual coexisting interconnected graphene nanostructures for high performance supercapacitor applications

Kim, Hyun-Kyung,Kamali, Ali Reza,Roh, Kwang Chul,Kim, Kwang-Bum,Fray, Derek John The Royal Society of Chemistry 2016 ENERGY AND ENVIRONMENTAL SCIENCE Vol.9 No.7

<P>A facile and scalable high-temperature molten salt method was used to synthesize a high-quality hierarchical carbon nanostructure consisting of graphene nanosheets and nanoscrolls with an interconnected network and high electrical conductivity. During the process, the intercalation of lithium and hydrogen from molten LiCl into graphite led to the formation of a coexisting graphene sheetscroll nanostructure. An electrode using the fabricated interconnected carbon nanostructure showed a highly reversible specific capacitance of 213 F g(-1) at 1 A g(-1), excellent capacitance retention (84.5% of the initial specific capacitance (1 A g(-1)) at 50 A g(-1)), and good cyclability (97.9% after 10000 cycles). Such remarkable electrochemical performance is desirable for supercapacitor/ultracapacitor applications.</P>