Implementation of Thermite Reactions in the Production of Advanced Intermetallic-Matrix Composites: The Case of Nb2O5/Al Thermite Mixture

Arman Ahmadi‑Binahri,Mandana Adeli,M. Reza Aboutalebi,Sergey Krasikov 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.6

In this study, the application of thermite reactions in Nb2O5–Al system in the fabrication of novel NbAl3/Al2O3 compositeswas investigated. Combining the thermite reactions with self-propagating high-temperature synthesis (SHS) techniquein compressed powder mixtures of Nb2O5+ Al resulted in layer-by-layer progress of the exothermic reaction, controlledformation of the desired products and their coexistence in each reacted layer. Characterization of the products using X-raydiffraction (XRD), scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS) techniques showedthat all samples were composed of a metallic matrix including NbAl3as the main compound, along with Al2O3as ceramicreinforcing phase. Differential thermal analysis (DTA) analysis was used to study the mechanism of reaction using bothstoichiometric and over-stoichiometric amounts of aluminum. The effect of such parameters as stoichiometry and greendensity of the samples on the combustion temperature, formed phases, microstructure, and hardness of the obtained compositeswas investigated using samples with stoichiometric as well 20 wt% and 40 wt% excess aluminum, and samples withgreen densities of 75%, 85%, and 95% of theoretical maximum density (TMD). The presence of excess aluminum resultedin prolonged reaction times, lower combustion temperatures, and lower mean values of hardness. While the variations ingreen density had no remarkable effect on the microstructural features of products within the density range under study, themost intensive reactions, highest combustion temperature, and highest mean value of hardness were encountered in sampleswith green density of 85%TMD.

Manufacturing of low cost MoSi2/Al2O3 composites by microwave activated self propagating high temperature Synthesis

Arman Sedghi 한양대학교 세라믹연구소 2013 Journal of Ceramic Processing Research Vol.14 No.1

In this research, low cost MoSi2/Al2O3 composites with various amounts of molybdenum oxide, silica and aluminum were prepared by a microwave activated self propagating high temperature synthesis method. The effect of pressure and microwave radiation time on the physical properties and chemical composition of these composites were investigated. The results showed that for compression of green samples, a maximum density and a minimum porosity can be achieved by applying 300 MPa pressure and increasing the microwave radiation time, would lead to the desired phases and completion of the reaction. After 50 seconds of microwave radiation, the sintering density and hardness would reach the maximum values of 4.75 g/cm3 and 1015 Vickers respectively

Comparison of electrical properties of zinc oxide varistors manufactured from micro and nano ZnO powder

Arman Sedghi,Nastaran Riyahi Noori 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.6

Zinc oxide varistors are semiconductor ceramics, which their excellent nonlinear electrical characteristics which are induced from their grain boundaries and depend on their microstructures. Based on a theoretical aspect, finer primary particles with a narrow size distributions offer better electrical properties. Then these properties are related to the size and morphology of ZnO grains. In this research, zinc oxide micro and nano powders were synthesized by a sol-gel method and the effect of the ZnO particle size on the electrical properties of zinc oxide varistors was investigated. The results showed that if ZnO nano powder is used instead of micro powder for fabrication of varistors, the sintering time and temperature were decreased; also,the electrical properties such as the nonlinear coefficient and breakdown voltage were increased up to 43 and 4750 V/cm versus 34.8 and 2920 V/cm respectively.

Multi-Criteria Supplier Selection Decisions in Supply Chain Networks

Arman Sajedinejad,Seyed Kamal Chaharsooghi 대한산업공학회 2018 Industrial Engineeering & Management Systems Vol.17 No.3

Competition among firms in current global market shifts to competition among networks of firms and it forces supply networks to negotiate and cooperate with all partners more than ever. Collaborative initiatives such as collaborative design, collaborative planning, forecasting and open collective innovations are increasingly accepted as approaches to effectively support decision-making processes in a variety of domains, including, manufacturing, education, healthcare and software industry (Camilleri and Hernández, 2016). Demands and constraints in the supply chain design operations are worthy of attention. The present paper is intended to study the supplier selection problem in a network of suppliers and buyers in the context of a multi-product supply chain. In the beginning, quality measures for supplier selection are collected and categorized into seven areas. Every quality area has been evaluated using the proposed fuzzy variables. In order to rank each product of each supplier in the view of every buyer, fuzzy AHP algorithm was applied. A multi-objective integer programing model was designed to make the whole network beneficial from cost as well as quality metrics. A Genetic Algorithm (3 dimensional) was presented in this study to gain acceptable solution in an advance way. An illustrative example is presented in this paper to transparent the proposed algorithm.

Effect of Synthesis Mode and Ni Particle Size on Microstructural Aspects and Hardness Properties of Combustion-Synthesized NiTi

Arman Khobzi,Mandana Adeli,Ashkan Sabour‑Bagherzadeh,Ashkan Arab,Hooman Abedi 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5

NiTi intermetallic compound was fabricated via two modes of the combustion synthesis process, namely, thermal explosion(TE) and self-propagating synthesis (SHS). The effect of combustion synthesis mode as well as Ni particle size on themicrostructure and microhardness of the final products was investigated. The phases in the products were determined usingXRD technique, and microstructural investigations were performed using optical as well as SEM-EDS in order to make acomparison between microstructural evolutions in each mode, other conditions being constant. The analyses showed thatthe desired B2(NiTi) was successfully formed as the primary phase in all samples, and no unreacted Ni or Ti powders werepresent. The main secondary phase was NiTi2which was invariably present in all samples; however, the percentage as wellas the morphology of the detrimental NiTi2phase was found out to be controllable by the mode of combustion as well asNi particle size. A comparison between the two modes revealed that samples produced by TE showed coarse dendritesin the microstructure; they also presented higher average microhardness values. The SHS-synthesized samples exhibitedmicrostructures similar to those observed in heat-treated and homogenized NiTi obtained from methods such as vacuum arcremelting and vacuum induction melting, and contained finely dispersed NiTi2particles. It was shown that a decrease in Niparticle size presented a grain refining effect on NiTi2in both modes.

The Effect of Nutrition Education Program on Overweight/Obese Patients with Non-Alcoholic Fatty Liver Disease: a Single-Blind Parallel Randomized Controlled Trial

( Arman Arab ),( Amir Hadi ),( Seyedeh Parisa Moosavian ),( Nahid Rafie ),( Hossein Hajianfar ) 한국임상영양학회 2019 Clinical Nutrition Research Vol.8 No.3

The aim of this study was to assess the effects of a nutrition education program on overweight/obese patients with non-alcoholic fatty liver disease (NAFLD). This single-blind, parallel randomized controlled trial was conducted on 82 NAFLD patients (mean age 48.89 ± 9.85 years) in Isfahan, Iran. Patients were randomly allocated to receive nutrition education program combined with usual care or usual care alone for 2 months. Metabolic markers, including lipid profile, fasting blood glucose (FBG) and dietary intakes were obtained for each patient at baseline and at the end of the study. Nutrition education intervention resulted in a significant decrease compared with usual care in serum levels of total cholesterol (TC) and triglyceride (TG) (p < 0.05). However, our intervention did not lead to a significant improvement in FBG, low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C), respectively (p > 0.05). Furthermore, energy and sugar intakes of patients were reduced significantly in response to our intervention (p < 0.05). Nutrition education intervention significantly reduced serum levels of TC and TG but did not affect other metabolic markers including FBG, LDL-C, and HDL-C. Also, it could reduce total energy and sugar intake. Thus, this study could be useful to use this educational program for NAFLD patients in order to influence their metabolic markers and dietary intakes.

Design a Methodology to Model-Reference Control of First Order Delays System

Arman Jahed,Farzin Piltan,Saman Namvarrechi,Iman Nazari,Ali Roshanzamir,Nasri B. Sulaiman 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.3

Design a nonlinear controller for second order nonlinear uncertain dynamical systems is one of the most important challenging works. This research focuses on the design, and analysis of a model-reference sliding mode controller for first order delay system, in presence of uncertainties. In order to provide high performance nonlinear methodology, model-reference sliding mode controller is selected. Pure sliding mode controller can be used to control of partly known nonlinear dynamic parameters. Conversely, pure sliding mode controller is used in many applications; it has an important drawback namely; chattering phenomenon. To attenuation the chattering, new filter based high speed control technique is introduced. In this technique, two type derivative techniques are used to improve the rate of delay as well stability, robustness and chattering attenuation. This technique cased to improve the rate of delay compare with conventional PID controller and conventional sliding mode controller.

A Study on the influence of thermal energy on the behaviour of TaOx-based RRAM

Arman Kadyrov,Kyesan Lee,Seunghyun Lee 한국통신학회 2022 한국통신학회 학술대회논문집 Vol.2022 No.11

ABOUT THE ANCIENT RITUAL OF DAMAGE TO ITEMS PLACED IN THE GRAVE

Arman Beisenov,Gulnar Jumabekova 가천대학교 아시아문화연구소 2016 아시아문화연구 Vol.41 No.-

The archaeologists have many facts stating that the ancient graves had objects that were intentionally spoiled before putting them into the grave. This tradition was widespread both chronologically and geographically, and, therefore, it is not associated with certain cultures or regions. A new fact about this ritual was recorded in 2015 in the study of the burial ground of the middle Sarmatian period Borsyk which is located in West Kazakhstan. The central grave of the kurgan 6 had badly damaged bronze cauldron. The grave was robbed in antiquity. Some scattered bones of a human skeleton, small ornaments of gold foil from the full dress of a nobleman were found in the grave. The diameter of the kurgan 50 m, height – 1,7 m .Dimensions of graves at the top - 4,5x3,8 m. Its depth - 2.3 m. The parameters of the kurgan and the grave, the nature of the findings show that this monument was the burial place of the representative of the Sarmatian elite. The cauldron is located in the northern corner of the grave and is strongly deformed. It has been bent and folded double. Along the edges, there are numerous destructions, traces of numerous blows by metal tool on the surface. As a result there are deep dents, cracks. Around the cauldron its small fragments were found. Thus, it is quite obvious that the boiler has been intentionally deformed by participants of the ancient ritual. Currently, the researchers have not expressed their unequivocal opinion about the essence of the ritual. The main hypothesis of the scientists is to ensure that the damage of ritual objects was associated with the idea of enduing the subjects with ‘other’, unearthly qualities that are originated from the owner’s death. Cauldrons have played an important role in the life of steppe leaders. It is assumed that the sacred nature of the use of them (bowls) in the culture of the steppe peoples is associated with the feast, the battle, the sacred hunting. Perhaps there was a tradition to bury the cauldrons with their owners, after making a damage of the subject in connection with the concept of the other world and the role of the leader-hero in it.

Early outcomes of cleft and palatal width following anterior palate repair (vomerine flap) in infants with wide cleft lip and palate

Arman Zaharil Mat Saad,Koh Siang Chai,Wan Azman Wan Sulaiman,Siti Fatimah Noor Mat Johar,Ahmad Sukari Halim 대한성형외과학회 2019 Archives of Plastic Surgery Vol.46 No.6

Background Anterior palatal repair performed during cleft lip repair using a vomerine flapmay assist in recruiting additional soft tissue for subsequent completion of palatoplasty, especiallyin patients with a wide cleft. We present our early results in the hope of triggering are-evaluation of this technique regarding its advantages for maxillary growth through furtherstudies of patients with a wide cleft. Methods A retrospective analysis of patients with complete unilateral and bilateral cleft lipand palate was performed, including cleft and palatal measurements taken during initial surgery(lip repair together with anterior palate repair) and upon completion of palatoplasty. Results In total, 14 patients were included in this study, of whom nine (63.3%) had unilateralcleft lip and palate and five (37.5%) had bilateral cleft. All patients had a wide cleft palate. Lip and anterior palate repair was done at a median age of 3 months, while completion ofpalatoplasty was done at a median age of 10.5 months. Measurements taken upon completionof palatoplasty showed significant cleft width reduction in the mid-palate and intertubercleregions; however, the palatal arch distances at nearby landmarks showed non-significantmarginal changes. Conclusions Anterior palate repair using a vomerine flap significantly reduced the remainingcleft width, while the palatal width remained. Further research is warranted to explore thelong-term effects of this technique in wide cleft patients in terms of facial growth.