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Spin Excitons from Hybridized Heavy Quasiparticles in YbB12 and CeB6
Alireza Akbari,Peter Thalmeier 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.10
In f-electron compounds the small indirect hybridization gap which is on the scale of the Kondo temperature leads to an enhanced bare spin response around the zone boundary wave vector, Q =(π, π, π). Due to the interaction of hybridized quasiparticles a collective spin exciton resonance mode may appear within or at the gap threshold around Q. It was found in the small hybridization gap semiconductor YbB12 as well as in the heavy fermion metal CeB6. There are similarities to the spin excitons observed within the excitation gap of unconventional superconductors. We use an Anderson lattice type model supplemented by the molecular fields of hidden and magnetic order in the case of CeB6 to calculate the RPA spin response in these compounds. It exhibits the salient feature in frequency and momentum dependence around Q found by inelastic neutron scattering.
Modeling and control of a flexible continuum module actuated by embedded shape memory alloys
Alireza Hadi,Hossein Akbari 국제구조공학회 2016 Smart Structures and Systems, An International Jou Vol.18 No.4
Continuum manipulators as a kind of mechanical arms are useful tools in special robotic applications. In medical applications, like colonoscopy, a maneuverable thin and flexible manipulator is required. This research is focused on developing a basic module for such an application using shape memory alloys (SMA). In the structure of the module three wires of SMA are uniformly distributed and attached to the circumference of a flexible tube. By activating wires, individually or together, different rotation regimes are provided. SMA model is used based on Brinson work. The SMA model is combined to model of flexible tube to provide a composite model of the module. Simulating the model in Matlab provided a platform to be used to develop controller. Complex and nonlinear behavior of SMA make the control problem hard especially when a few SMA actuators are active simultaneously. In this paper, position control of the two degree of freedom module is under focus. An experimental control strategy is developed to regulate a desired position in the module. The simulation results present a reasonable performance of the controller. Moreover, the results are verified through experiments and show that the continuum module of this paper would be used in real modular manipulators.
Akbari, Reza,Maadani, Saeed,Abedi, Alireza,Maalek, Shahrokh Techno-Press 2019 Structural monitoring and maintenance Vol.6 No.2
The effects of foundation scour depth and riverbed condition on the natural frequencies of a typical cross-river integral abutment bridge have been studied. The conventional operational modal analysis technique has been employed in order to extract the modal properties of the bridge and the results have been used in the Finite Element (FE) model updating procedure. Two tests have been carried out in two different levels of water and wet condition of the riverbed. In the first test, the riverbed was in dry condition for two subsequent years and the level of water was 10 meter lower than the natural riverbed. In the second test, the river was opened to water flow from the upstream dam and the level of water was 2 meter higher than the natural riverbed. The results of these two tests have also been used in order to find to what extend the presence of water flow in the river and saturation of the surrounding soil affect the bridge natural frequencies. Finally, the updated FE model of the bridge has been applied in a series of parametric analyses incorporating the effect of piles' relative scour depth on the bridge natural frequency of the first four vibration modes.
Alireza Bahramian,Mohsen Mohammadi,Mahdi Akbari,Mahdi Sadeghi Naeeni,Zahra Fakhroueian 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.2
The effects of N2, CH4 and CO2 injection on asphaltene precipitation have been experimentally investigated using a reservoir oil fluid from south of Iran, making use of light transmission method. The results are compared and the effects of injected gases on reducing asphaltene colloidal stability in oil are found in the following order: CH4>N2>CO2. It is observed that CO2 can act like an inhibitor and can increase the solubility of asphaltene, decreasing the asphaltene precipitation onset. A thermodynamic discussion explains the effect of CO2 on the solubility of asphaltene based on the solubility parameters of recombined oil and CO2, calculated from Peng-Robinson equation of state along with an empirical correlation for volumetric properties of CO2.
Influencing Parameters on Supercritical Water Reactor Design for Phenol Oxidation
( Maryam Akbari ),( Morteza Nazaripour ),( Alireza Bazargan ),( Majid Bazargan ) 한국화학공학회 2021 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.59 No.1
For accurate and reliable process design for phenol oxidation in a plug flow reactor with supercritical water, modeling can be very insightful. Here, the velocity and density distribution along the reactor have been predicted by a numerical model and variations of temperature and phenol mass fraction are calculated under various flow conditions. The numerical model shows that as we proceed along the length of the reactor the temperature falls from above 430℃ to approximately 380℃. This is because the generated heat from the exothermic reaction is less that the amount lost through the walls of the reactor. Also, along the length, the linear velocity falls to less than one-third of the initial value while the density more than doubles. This is due to the fall in temperature which results in higher density which in turn demands a lower velocity to satisfy the continuity equation. Having a higher oxygen concentration at the reactor inlet leads to much faster phenol destruction; this leads to lower capital costs (shorter reactor will be required); however, the operational expenditures will increase for supplying the needed oxygen. The phenol destruction depends heavily on the kinetic parameters and can be as high as 99.9%. Using different kinetic parameters is shown to significantly influence the predicted distributions inside the reactor and final phenol conversion. These results demonstrate the importance of selecting kinetic parameters carefully particularly when these predictions are used for reactor design.
Shiva Torabian,Alireza Soffianian,Sima Fakheran,Ali Asgarian,Hossein Akbari Feizabad,Josef Senn 대한공간정보학회 2018 Spatial Information Research Vol.26 No.1
One of the primary reason of species extinction especially rare species with very specific requirements, is habitat destruction. To protect these species, habitat suitability evaluation plays a central role. Hence, an attempt is made in this study to evaluate the suitability of sand cat’s habitat in a sand dune-dominated landscape in Iran. Four Landsat-derived indices including Normalized Difference Vegetation Index (NDVI), Weighted Difference Vegetation Index, Brightness Index (BI) and Salinity Index were combined to characterize sand cat’s habitat requirements through a land use land cover (LULC) map. Furthermore, a set of landscape metrics were employed to explore the spatial pattern LULC classes. Sand cat’s habitat suitability map was generated by linear combination of the standardized and relatively weighted NDVI and BI indices and then categorized into five classes of most suitable, highly suitable, moderately suitable, least suitable and not suitable. The results showed that about 75% of the total area is suitable for sand cat. Although this region is rich in biodiversity, it has not yet been subject to any conservation planning and should be granted more conservation attentions.
Genomic Profiling of Chronic Myelogenous Leukemia: Basic and Clinical Approach
Aliasghar Keramatinia,Alireza Ahadi,Mohammad Esmaeil Akbari,Maryam Mohseny,Alireza Mosavi Jarahi,Narjes Mehrvar,Neda Mansouri,S.A. Mortazavi Tabatabaei,Abolfazl Movafagh 대한암예방학회 2017 Journal of cancer prevention Vol.22 No.2
Chronic myeloid leukemia (CML) is a hematological stem cell cancer driven by BCR-ABL1 fusion protein. We review the previous and recent evidence on the significance of CML in diagnostic and clinic management. The technical monitoring of BCR-ABL1 with quantitative real time-PCR has been used in assessing patient outcome. The cytogenetic mark of CML is Philadelphia chromosome, that is formed by reciprocal chromosomal translocations between human chromosome 9 and 22, t(9:22) (q34:q11). It makes a BCR-ABL1 fusion protein with an anomaly tyrosine kinase activity that promotes the characteristic proliferation of progenitor cells in CML and acute lymphoblastic lymphoma. The targeting of BCR-ABL1 fusion kinase is the first novel paradigm of molecularly targeted curing.