SKEW LAURENT POLYNOMIAL EXTENSIONS OF BAER AND P.P.-RINGS

Nasr-Isfahani, Alireza R.,Moussavi, Ahmad Korean Mathematical Society 2009 대한수학회보 Vol.46 No.6

Let R be a ring and ${\alpha}$ a monomorphism of R. We study the skew Laurent polynomial rings R[x, x$^{-1}$; ${\alpha}$] over an ${\alpha}$-skew Armendariz ring R. We show that, if R is an ${\alpha}$-skew Armendariz ring, then R is a Baer (resp. p.p.-)ring if and only if R[x, x$^{-1}$; ${\alpha}$] is a Baer (resp. p.p.-) ring. Consequently, if R is an Armendariz ring, then R is a Baer (resp. p.p.-)ring if and only if R[x, x$^{-1}$] is a Baer (resp. p.p.-)ring.

Enhancement of the gas separation properties of polyurethane membrane by epoxy nanoparticles

Ali Pournaghshband Isfahani,Morteza Sadeghi,Amir H. Saeedi Dehaghani,M. Ali Aravand 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.44 No.-

In this study, we report highly selective CO2 polyurethane incorporated with cured epoxy nanoparticles. PU–epoxy composite membranes were prepared via solution casting method. The obtained SEMmicrographs confirmed the nano-scale distribution of epoxy particles in the polymer matrix. DSC andFTIR spectra showed different phase separation for the PU composites compared to the pure PU. Theeffect of epoxy nanoparticles on the gas permeability of CO2, CH4, O2 and N2 was studied at 25 8C and10 bar. The selectivity of CO2/N2 increased from 25 for the pure PU membrane to 55.5 for the PU–EP10,while the CO2 permeability was unchanged.

Equality of Human Opportunities in the Middle East and North Africa

Djavad Salehi-Isfahani,Atiyeh Vahidmanesh 연세대학교 빈곤문제국제개발연구원 2022 Asian Development Perspectives (ADP) Vol.13 No.1

We present estimates of the Human Opportunity Index (HOI) for 10 countries in the Middle East and North Africa (MENA) using harmonized household expenditure and income surveys. The index measures equality of opportunity in access to basic services (electricity, piped water, sanitation and basic education) by children. MENA governments play a large role in provision of these services, so how equitably they are provided determines the life chances of MENA children and overall equality of opportunity in these countries. We find that HOI levels in MENA countries have improved over time and compare favorably with similar measures computed for other countries, notably those in Latin America. Our findings broadly indicate that authoritarian MENA governments that are widely criticized for failing to foster dynamic economies and deliver jobs and high economic growth, have done reasonably well in providing access to basic services and ensuring that they are delivered relatively equitably. We provide decompositions of HOI for individual outcomes over time to account for the contribution of the change in average access vs. its distribution to change in the HOI. We also provide the Shapley decompositions of the Dissimilarity Index of the outcomes to gain insight into the significance of different circumstances to changes in the HOI.

Skew Laurent polynomial extensions of Baer and p.p.-rings

Alireza R. Nasr-Isfahani,Ahmad Moussavi 대한수학회 2009 대한수학회보 Vol.46 No.6

Let R be a ring and α a monomorphism of R. We study the skew Laurent polynomial rings R[x, x^(−1);α] over an α-skew Armendariz ring R. We show that, if R is an α-skew Armendariz ring, then R is a Baer (resp. p.p.-)ring if and only if R[x, x^(−1);α] is a Baer (resp. p.p.-) ring. Consequently, if R is an Armendariz ring, then R is a Baer (resp. p.p.-)ring if and only if R[x, x^(−1)] is a Baer (resp. p.p.-)ring. Let R be a ring and α a monomorphism of R. We study the skew Laurent polynomial rings R[x, x^(−1);α] over an α-skew Armendariz ring R. We show that, if R is an α-skew Armendariz ring, then R is a Baer (resp. p.p.-)ring if and only if R[x, x^(−1);α] is a Baer (resp. p.p.-) ring. Consequently, if R is an Armendariz ring, then R is a Baer (resp. p.p.-)ring if and only if R[x, x^(−1)] is a Baer (resp. p.p.-)ring.

Optimal Design of a Direct-Drive Permanent Magnet Synchronous Generator for Small-Scale Wind Energy Conversion Systems

Mohammadali Abbasian,Arash Hassanpour Isfahani 한국자기학회 2011 Journal of Magnetics Vol.16 No.4

This paper presents an optimal design of a direct-drive permanent magnet synchronous generator for a smallscale wind energy conversion system. An analytical model of a small-scale grid-connected wind energy conversion system is presented, and the effects of generator design parameters on the payback period of the system are investigated. An optimization procedure based on genetic algorithm method is then employed to optimize four design parameters of the generator for use in a region with relatively low wind-speed. The aim of optimization is minimizing the payback period of the initial investment on wind energy conversion systems for residential applications. This makes the use of these systems more economical and appealing. Finite element method is employed to evaluate the performance of the optimized generator. The results obtained from finite element analysis are close to those achieved by analytical model.

Optimal flammability and thermal buckling resistance of eco-friendly abaca fiber/ polypropylene/egg shell powder/halloysite nanotubes composites

Saeed Kamarian,Reza Barbaz-Isfahani,Thanh Mai Nguyen Tran,Jung-Il Song Techno-Press 2024 Advances in nano research Vol.16 No.2

Upon direct/indirect exposure to flame or heat, composite structures may burn or thermally buckle. This issue becomes more important in the natural fiber-based composite structures with higher flammability and lower mechanical properties. The main goal of the present study was to obtain an optimal eco-friendly composite system with low flammability and high thermal buckling resistance. The studied composite consisted of polypropylene (PP) and short abaca fiber (AF) with eggshell powder (ESP) and halloysite clay nanotubes (HNTs) additives. An optimal base composite, consisting of 30 wt.% AF and 70 wt.% PP, abbreviated as OAP, was initially introduced based on burning rate (BR) and the Young's modulus determined by horizontal burning test (HBT) and tensile test, respectively. The effects of adding ESP to the base composite were then investigated with the same experimental tests. The results indicated that though the BR significantly decreased with the increase of ESP content up to 6 wt.%, it had a very destructive influence on the stiffness of the composite. To compensate for the damaging effect of ESP, small amount of HNT was used. The performance of OAP composite with 6 wt.% ESP and 3 wt.% HNT (OAPEH) was explored by conducting HBT, cone calorimeter test (CCT) and tensile test. The experimental results indicated a 9~23 % reduction in almost all flammability parameters such as heat release rate (HRR), total heat released (THR), maximum average rate of heat emission (MARHE), total smoke released (TSR), total smoke production (TSP), and mass loss (ML) during combustion. Furthermore, the combination of 6 wt.% ESP and 3 wt.% HNT reduced the stiffness of OAP to an insignificant amount by maximum 3%. Moreover, the char residue analysis revealed the distinct differences in the formation of char between AF/PP and AF/PP/ESP/HNT composites. Afterward, dilatometry test was carried out to examine the coefficient of thermal expansion (CTE) of OAP and OAPEH samples. The obtained results showed that the CTE of OAPEH composite was about 18% less than that of OAP. Finally, a theoretical model was used based on first-order shear deformation theory (FSDT) to predict the critical bucking temperatures of the OAP and OAPEH composite plates. It was shown that in the absence of mechanical load, the critical buckling temperatures of OAPEH composite plates were higher than those of OAP composites, such that the difference between the buckling temperatures increased with the increase of thickness. On the contrary, the positive effect of CTE reduction on the buckling temperature decreased by raising the axial compressive mechanical load on the composite plates which can be assigned to the reduction of stiffness after the incorporation of ESP. The results of present study generally stated that a suitable combination of AF, PP, ESP, and HNT can result in a relatively optimal and environmentally friendly composite with proper flame and thermal buckling resistance with no significant decline in the stiffness.

Using S Technology, in the Automotive Industry, with the Approach of Its Implementation in Commercial Vehicles

Soleimani, Gholamhossein,Amiri, Magsod,Khatami, Seyed Mohammadali,Isfahani, MohammadJavad Korean Institute of Industrial Engineers 2016 Industrial Engineeering & Management Systems Vol.15 No.4

The successful transfer of technology, needs to recognize the industrial purposes, resources, technology, innovation and the mode of transmission, methods of transmission, influential factors, it's how to recruit and how to develop, and each of these cognitive relies on special expertise. One of the important technologies is automotive technology, and s technology is important for the transition and its development in recent years. Hence, in this paper, after studying Iran and the world's automotive and emerging technologies situation, the status of commercial vehicles and s technology model are studied based on external models, technical specifications, and cost. In this way, we examine the incidence and the applicability of the technology used in the production of heavy-duty vehicles, in recent years, with the passage of time, and we examine the technology lifecycle, from the perspective of physical characteristics and technical features. The results show that the technology of the studied heavy-duty vehicles (Titan) is close to the time of his fall, because spending puberty, so, according to the investigation of new technologies, we should strive to create changes in vehicle technology.

Predicting ESP and HNT effects on the mechanical properties of eco-friendly composites subjected to micro-indentation test

Saeed Kamarian,Ali Khalvandi,Thanh Mai Nguyen Tran,Reza Barbaz-Isfahani,Saeed Saber-Samandari,Jung-Il Song Techno-Press 2023 Advances in nano research Vol.15 No.4

The main goal of the present study was to assess the effects of eggshell powder (ESP) and halloysite nanotubes (HNTs) on the mechanical properties of abaca fiber (AF)-reinforced natural composites. For this purpose, a limited number of indentation tests were first performed on the AF/polypropylene (PP) composites for different HNT and ESP loadings (0 wt.% ~ 6 wt.%), load amplitudes (150, 200, and 250 N), and two types of indenters (Vickers or conical). The Young's modulus, hardness and plasticity index of each specimen were calculated using the indentation test results and Oliver-Pharr method. The accuracy of the experimental results was confirmed by comparing the values of the Young's modulus obtained from the indentation test with the results of the conventional tensile test. Then, a feed-forward shallow artificial neural network (ANN) with high efficiency was trained based on the obtained experimental data. The trained ANN could properly predict the variations of the mentioned mechanical properties of AF/PP composites incorporated with different HNT and ESP loadings. Furthermore, the trained ANN demonstrated that HNTs increase the elastic modulus and hardness of the composite, while the incorporation of ESP reduces these properties. For instance, the Young's modulus of composites incorporated with 3 wt.% of ESP decreased by 30.7% compared with the pure composite, while increasing the weight fraction of ESP up to 6% decreased the Young's modulus by 34.8%. Moreover, the trained ANN indicated that HNTs have a more significant effect on reducing the plasticity index than ESP.

Using S Technology, in the Automotive Industry, with the Approach of Its Implementation in Commercial Vehicles

Gholamhossein Soleimani,Magsod Amiri,Seyed Mohammadali Khatami,MohammadJavad Isfahani 대한산업공학회 2016 Industrial Engineeering & Management Systems Vol.15 No.4

The successful transfer of technology, needs to recognize the industrial purposes, resources, technology, innovation and the mode of transmission, methods of transmission, influential factors, it’s how to recruit and how to develop, and each of these cognitive relies on special expertise. One of the important technologies is automotive technology, and s technology is important for the transition and its development in recent years. Hence, in this paper, after studying Iran and the world’s automotive and emerging technologies situation, the status of commercial vehicles and s technology model are studied based on external models, technical specifications, and cost. In this way, we examine the incidence and the applicability of the technology used in the production of heavy-duty vehicles, in recent years, with the passage of time, and we examine the technology lifecycle, from the perspective of physical characteristics and technical features. The results show that the technology of the studied heavy-duty vehicles (Titan) is close to the time of his fall, because spending puberty, so, according to the investigation of new technologies, we should strive to create changes in vehicle technology.