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EXCHANGE RATE FORECASTING WITH OPTIMUM SINGULAR SPECTRUM ANALYSIS

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Journal of Systems Science & Complexity 2014年第1期27卷 47-55页

作者： GHODSI Mansi yarmohammadi masoud Executive Business Center Bourremouth University 89 Holdenhurst Road BH8 8EB UK Institute for In-ternational Energy Studies Tehran Iran. Department of Statistics Payame Noor University 19395-3697 Tehran I. R. Iran.

Forecasting exchange rate is undoubtedly an attractive and challenging issue that has been of interest in different domains for many years. The singular spectrum analysis （SSA） technique has been used as a promising technique for time series forecasting including exchange rate series. The SSA technique is based upon two main choices： Window length, L, and the number of singular values, r. These values are very important for the reconstruction stage and forecasting purposes. Here the authors consider an optimum version of the SSA technique for forecasting exchange rates. The forecasting performances of the SSA technique for one-step-ahead forecast of six exchange rate series are used to find the best L and r.

关键词： Exchange rate forecasting optimal singular spectrum analysis singular value windowlength.

Orbital electronic heat capacity of hydrogenated monolayer and bilayer graphene

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Chinese Physics B 2017年第2期26卷 375-381页

作者： Mohsen yarmohammadi Young Researchers and Elite Club Kermanshah Branch Islamic Azad University Kermanshah Ira

The tight-binding Harrison model and Green＇s function approach have been utilized in order to investigate the contribution of hybridized orbitals in the electronic density of states（DOS） and electronic heat capacity（EHC） for four hydrogenated structures, including monolayer chair-like, table-like, bilayer AA- and finally AB-stacked graphene. After hydrogenation, monolayer graphene and bilayer graphene are behave as semiconducting systems owning a wide direct band gap and this means that all orbitals have several states around the Fermi level. The energy gap in DOS and Schottky anomaly in EHC curves of these structures are compared together illustrating the maximum and minimum band gaps are appear for monolayer chair-like and bilayer AA-stacked graphane, respectively. In spite of these, our findings show that the maximum and minimum values of Schottky anomaly appear for hydrogenated bilayer AA-stacked and monolayer table-like configurations, respectively.

关键词： hydrogenated monolayer and bilayer graphene Harrison model electronic heat capacity density of states Green's function

Bound states of Dirac fermions in monolayer gapped graphene in the presence of local perturbations

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Chinese Physics B 2016年第6期25卷 563-568页

作者： Mohsen yarmohammadi Malek Zareyan Young Researchers and Elite Club Kermanshah BranchIslamic Azad University Department of Physics Institute for Advanced Studies in Basic Sciences (IASBS)

In graphene,conductance electrons behave as massless relativistic particles and obey an analogue of the Dirac equation in two dimensions with a chiral *** this reason,the bounding of electrons in graphene in the form of geometries of quantum dots is *** gapless graphene,due to its unique electronic band structure,there is a minimal conductivity at Dirac points,that is,in the limit of zero *** creates a problem for using such a highly motivated new material in electronic *** of the ways to overcome this problem is the creation of a band gap in the graphene band structure,which is made by inversion symmetry breaking（symmetry of sublattices）.We investigate the confined states of the massless Dirac fermions in an impured graphene by the short-range perturbations for ＂local chemical potential＂ and ＂local gap＂.The calculated energy spectrum exhibits quite different features with and without the perturbations.A characteristic equation for bound states（BSs） has been *** is surprisingly found that the relation between the radial functions of sublattices wave functions,i.e.,f_m~＋（r）,g_m~＋（r）,and f_m^-（r）,g_m^-（r）,can be established by SO（2） group.

关键词： monolayer gapped graphene quantum dots bound states inversion symmetry breaking

Spin-valley Hall conductivity of doped ferromagnetic silicene under strain

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Chinese Physics B 2017年第1期26卷 410-416页

作者： Bahram Shirzadi Mohsen yarmohammadi Department of Physics Razi University Kermanshah Iran Young Researchers and Elite Club Kermanshah Branch Islamic Azad University Kermanshah Iran

The spin-valley Hall conductivity（SHC-VHC） of two-dimensional material ferromagnetic graphene＇s silicon analog,silicene, is investigated in the presence of strain within the Kubo formalism in the context of the Kane–Mele *** Dirac cone approximation has been used to investigate the dynamics of carriers under the strain along the armchair（AC） direction. In particular, we study the effect of external static electric field on these conductivities under the *** the presence of the strain, the carriers have a larger effective mass and the transport decreases. Our findings show that SHC changes with respect to the direction of the applied electric field symmetrically while VHC increases ***, the reflection symmetry of the structure has been broken with the electric field and a phase transition occurs to topological insulator for strained ferromagnetic silicene. A critical strain is found in the presence of the electric field around 45%. SHC（VHC） decreases（increases） for strains smaller than this value symmetrically while it increases（decreases） for strains larger than one.

关键词： ferromagnetic silicene Kubo formalism strain spin-valley conductivity

Controlling Thermodynamic Properties of Ferromagnetic Group-Ⅳ Graphene-Like Nanosheets by Dilute Charged Impurity

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Communications in Theoretical Physics 2017年第5期67卷 569-576页

作者： Mohsen yarmohammadi Kavoos Mirabbaszadeh Department of Energy Engineering and Physics Amirkabir University of Technology Tehran Iran

Using the Kane-Mele Hamiltonian, Dirac theory and self-consistent Born approximation, we investigate the effect of dilute charged impurity on the electronic heat capacity and magnetic susceptibility of two-dimensional ferromagnetic honeycomb structure of group-Ⅳ elements including silicene, germanene and stanene within the Green's function approach. We also find these quantities in the presence of applied external electric field. Our results show that the silicene(stanene) has the maximum(minimum) heat capacity and magnetic susceptibility at uniform electric fields. From the behavior of theses quantities, the band gap has been changed with impurity concentration, impurity scattering strength and electric field. The analysis on the impurity-dependent magnetic susceptibility curves shows a phase transition from ferromagnetic to paramagnetic and antiferromagnetic phases. Interestingly, electronic heat capacity increases(decreases) with impurity concentration in silicene(germanene and stanene) structure.

关键词： ferromagnetic group-Ⅳ elements Green's function electronic heat capacity magnetic susceptibility phase transition

Impurity effects on electrical conductivity of doped bilayer graphene in the presence of a bias voltage

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Chinese Physics B 2016年第7期25卷 316-323页

作者： E Lotfi H Rezania B Arghavaninia M yarmohammadi Department of Physics Sanandaj Branch Islamic Azad University Department of Physics Razi University Department of Physics Kermanshah Branch Islamic Azad University Young researchers and Elite Club Kermanshah Branch Islamic Azad University

We address the electrical conductivity of bilayer graphene as a function of temperature, impurity concentration, and scattering strength in the presence of a finite bias voltage at finite doping, beginning with a description of the tight-binding model using the linear response theory and Green＇s function approach. Our results show a linear behavior at high doping for the case of high bias voltage. The effects of electron doping on the electrical conductivity have been studied via changing the electronic chemical potential. We also discuss and analyze how the bias voltage affects the temperature behavior of the electrical conductivity. Finally, we study the behavior of the electrical conductivity as a function of the impurity concentration and scattering strength for different bias voltages and chemical potentials respectively. The electrical conductivity is found to be monotonically decreasing with impurity scattering strength due to the increased scattering among electrons at higher impurity scattering strength.

关键词： bilayer graphene Green's function electrical conductivity

Rabies in medieval Persian literature – the Canon of Avicenna (980–1037 AD)

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Infectious Diseases of Poverty 2014年第1期3卷 56-61页

作者： Behnam Dalfardi Mohammad Hosein Esnaashary Hassan yarmohammadi Student Research Committee Shiraz University of Medical SciencesShirazIran Research Office for the History of Persian Medicine Shiraz University of Medical SciencesShirazIran

Ibn Sina(980-1037 AD),known by his full name Abu Ali al-Hussain ibn Abdallah ibn Sina and the Latin name‘Avicenna’,was a Persian scholar who is primarily remembered for his contributions to the science of *** authored Al-Qanun fi al-Tibb(The Canon of Medicine).Sections of his work are devoted to detailed descriptions of a number of infectious illnesses,particularly *** described rabies in humans and animals and explained its clinical manifestations,route of transmission,and treatment *** this article,our goal is to discuss Avicenna’s 11th-century points of view on rabies and compare them with modern medical knowledge.

关键词： Avicenna Canon of medicine Medieval history Persia Rabie

Optimization of FX-70 refrigerant evaporative heat transfer and fluid flow characteristics inside the corrugated tubes using multi-objective genetic algorithm

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Chinese Journal of Chemical Engineering 2020年第8期28卷 2142-2151页

作者： Mirollah Hosseini Hamid Hassanzadeh Afrouzi Sina yarmohammadi Hossein Arasteh Davood Toghraie AJafarian Amiri Arash Karimipour Department of Mechanical Engineering Islamic Azad UniversityQaemshahr BranchQaemshahrMazandaranIran Faculty of Mechanical Engineering Babol Noshirvani University of TechnologyBabolIran Department of Mechanical Engineering Isfahan University of TechnologyIsfahanIran Department of Mechanical Engineering Khomeinishahr BranchIslamic Azad UniversityKhomeinishahrIran Sustainable Management of Natural Resources and Environment Research Group Faculty of Environment and Labour SafetyTon Duc Thang UniversityHo Chi Minh CityVietnam

In this study,the heat transfer optimization(evaporation)and the specification of the FX-70 zeotropic refrigerant flow inside a corrugated pipe have been *** the low HTC(HTC),this type of refrigerant is highly applicable in low or medium temperature engineering systems during the evaporation *** eliminate this defect,high turbulence and proper mixing are ***,using heat transfer(HT)augmentation methods will be necessary and *** order to find the most favorable operating conditions that lead to the optimum combination of pressure drop(PD)and HTC,empirical data,neural networks,and genetic algorithms(GA)for multi-objective(MO)(NSGA II)are *** investigate the mentioned cases,the geometric parameters of corrugated pipes,vapor quality,and mass velocity of refrigerant were *** results showed that with vapor quality higher than 0.8 and corrugation depth and pitch of 1.5 and 7 mm,respectively,we would achieve the desired optimum design.

关键词： Optimization Genetic algorithm Neural network Corrugated tube FX-70 refrigerant

Melancholia in medieval Persian literature: The view of Hidayat of Al-Akhawayni

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World Journal of Psychiatry 2014年第2期4卷 37-41页

作者： Behnam Dalfardi Hassan yarmohammadi Ahmad Ghanizadeh Student Rese-arch Committee Shiraz University of Medical Sciences Research Office for the History of Persian Medicine Shiraz University of Medical Sciences Research Center for Psychiatry and Be-havioral Sciences Shiraz University of Medical SciencesHafez Hospital

"Melancholia" seems to be the oldest term used to describe the manifestations of depression. Throughout the history of medicine, melancholia has been the focus of consideration of many scholars who have provided varying definitions of this disorder and its manifestations. This continual process has resulted in the gradual development of the concept of melancholia over time. Persian scholars were among the scientists who have studied the melancholia and contributed to its concept. One figure, Al-Akhawayni Bukhari(?-983 AD), a Persian physician whose reputation was based on the treatment of patients with mental problems, investigated this disorder. He described Melancholia and explained its clinical manifestations and treatment methods. AlAkhawayni provided an early classification of the patients suffering from this disorder. Since the medieval Persian concept of melancholia is not well-known, this paper aims to review Al-Akhawayni's 10 th century knowledge on melancholia which can represent the early concept of this disorder in the Near East.

关键词： Al-Akhawayni Bipolar disorder Conversion disorder Depression Melancholia Persian Personality disorders Psychiatry