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OPERATOR NORM AND LOWER BOUND OF FOUR-DIMENSIONAL GENERALIZED HAUSDORFF MATRICES

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Acta Mathematica Scientia 2022年第1期42卷 429-436页

作者： gholamreza TALEBI Department of Mathematical sciences Vali-e-Asr University of RafsanjanRafsanjanIslamic Republic of Iran

The problem addressed is the exact determination of the operator norm and lower bound of four-dimensional generalized Hausdorff matrices on the double sequence spaces L_(p).A Hardy type formulae is found as an exact value for their operator norm and a Copson type formulae is established as a lower estimate for their lower ***,exact values are found for the operator norm and lower bound of the transpose of generalized Hausdorff matrices.

关键词： four-dimensional Hausdorff matrices

Effect of transparency on Josephson junction between s+g-wave superconductors

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Chinese Physics B 2010年第10期19卷 499-504页

作者： gholamreza Rashedi Department of Physics University of Isfahan

In this paper, a dc Josephson junction between borocarbide superconductors has been studied theoretically. The s＋g-wave pairing symmetry which is observed in rare earth complex of borocarbides has a huge anisotropy and is an interesting form of unconventional superconductivity. We calculate the Josephson current in a superconductorinsulator-superconductor （SIS） Josephson junction with s＋g-wave superconducting pairing symmetry. In our planar junction c-axis is parallel to an interface with finite transparency but ab-planes of two tetragonal superconductors are misorientated by angle α. We obtain that the Josephson current is strongly dependent on mis-orientation between the left and the right ab-planes. An insulator sandwiched between two superconductors which acts as a potential barrier is demonstrated by a transparency coefficient. The effects of the potential barrier and the mis-orientation on the current are studied analytically and numerically. Occurrence of 0-θ transition in this s＋g-wave junction is investigated in this paper. A comparison between d-wave Josephson junction and s＋g-wave one is also made in the present paper.

关键词： Josephson junction unconventional superconductor borocarbides

Risk factors for congenital nasolacrimal duct obstruction in children under two years of age

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国际眼科杂志 2025年第1期25卷 17-23页

作者： Rozhin Kasiri gholamreza Khataminia Ali Kasiri Mohammad Sadegh Mirdehghan Mohammad Armin Kasiri Infectious Ophthalmologic Research Center Ahvaz Jundishapur University of Medical SciencesAhvaz ***Iran Islamic Azad University Tehran Medical Sciences Tehran ***Iran

·AIM:To identify various risk factors that may play a significant role in the development of congenital nasolacrimal duct obstruction(CNLDO).·METHODS:This observational case-control study included a case group of 122 children less than two years of age with CNLDO who underwent probing and irrigation treatment at the ophthalmology department of Imam Khomeini Hospital in Ahvaz,Iran,from June 2022 to June2024.A control group of 122 age-matched children without CNLDO was also included for *** was collected from the children's medical records.·RESULTS:The study found a significant correlation between the occurrence of CNLDO and several maternal factors,such as preeclampsia,the use of levothyroxine,hypothyroidism,having more than three pregnancies(gravidity>3),natural pregnancy,and gestational diabetes ***,in children,factors,such as oxygen therapy,anemia,reflux,jaundice,and a family history of CNLDO in first-degree relatives were associated with CNLDO,and maternal preeclampsia and hypothyroidism were found to significantly increase the risk of developing CNLDO in children.·CONCLUSION:Given that CNLDO affects both premature and full-term children,the present findings may potentially facilitate the early identification of children and infants at risk of nasolacrimal duct obstruction,thereby preventing the onset of chronic dacryocystitis.

关键词： risk factors congenital nasolacrimal duct obstruction children

Investigation of a novel pyrogenic pulser in a laboratory motor

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Chinese Journal of Aeronautics 2020年第1期33卷 134-148页

作者： Roohollah TAHERINEZHAD gholamreza ZAREPOUR Department of Mechanical Engineering University of GuilanRasht 51665-315Iran

In this paper,a novel pyrogenic pulser was designed both analytically and numerically and was evaluated with empirical *** motivation of this study was the need for active control of the aero acoustic pressure oscillations by injecting the secondary flow into the solid rocket ***,in brief,pyrotechnic and pyrogenic pulsers were introduced,and then analytical governing equations were presented in three transient,sinusoidal and Hercules *** order to understand the internal pressure of the pulsar and its plume length,the injection flow field was evaluated using the ANSYS-Fluent software with both k-ωSST and k-εRealizable models both at ambient and motor *** that,the design and manufacturing of the pulser hardware and the test process were ***,analytical,numerical and experimental results were *** results show that there is a good correlation between the transient analysis in theory and the numerical solution by the k-ωSST model and the empirical test *** addition,pyrogenic pulsers design depends on various parameters of motor and pulser charge performance *** quality of pulser charge bonding to its insulator and erosion of its throat path due to injection have an important role to obtain a desirable pulser mass flow rate and plume length.

关键词： Aero acoustic Pressure oscillation Pyrogenic pulsers Secondary injection Solid rocket motors

Evaluation of pressure oscillations by a laboratory motor

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Chinese Journal of Aeronautics 2020年第3期33卷 805-825页

作者： Roohollah TAHERINEZHAD gholamreza ZAREPOUR Department of Mechanical Engineering University of GuilanRasht 51665-315Iran

Aeroacoustic pressure oscillation is one of the important challenges in segmented solid rocket motors with high slenderness *** reason for these oscillations can be searched in vortex shedding due to grain burning surfaces, holes and *** this paper, a novel sub-scaled motor was used for evaluation of aeroacoustic pressure ***, the related parameters to scale down using Buckingham's Pi-theorem were determined and then the sub-scaled motor was designed and *** this, Strouhal number in various grain forms and vortex shedding prediction criteria have been ***, one-dimensional linear and non-linear solution approaches have been *** understand the motor internal flow and vortex shedding formation, steady state computational fluid dynamic performed for seven regression steps and finally, two static tests have been *** show that various definitions for Strouhal number are useful only for primarily glance on vortex shedding and pressure oscillations and so CFD solution and the test program are inevitable for a correct understanding of the ballistic operational condition of the *** results demonstrated the existence of such oscillations with frequencies nearly equal to axial *** seems that non-linear parameters have small effects on aeroacoustic pressure oscillation and therefore the linear solution is acceptable to obtain approximate *** course,it should be emphasized that linear solution represents oscillations on overall motor action time,whereas the output of non-linear solution depends on thermochemistry properties of solid propellant and combustion ***, with a non-linear solution, oscillations maybe occur in some intervals of action ***(Fast Fourier Transformation) results demonstrated that although both first and second acoustic modes have been excited, the position of longitudinal oscillation has an important role on which one is dominant.

关键词： Aeroacoustic Pressure oscillation Solid rocket motor Strouhal number Sub-scale Vortex shedding

Proposal of a probabilistic assessment of structural collapse concomitantly subject to earthquake and gas explosion

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Frontiers of Structural and Civil Engineering 2018年第3期12卷 425-437页

作者： gholamreza ABDOLLAHZADEH Hadi FAGHIHMALEKI Department of Civil Engineering Babol Noshirvani University of Technology Shariati Av. Babol Mazandaran Iran

In recent decades, many public buildings, located in seismic-prone residential areas, had to grapple with abnormal loads against which the structures were unguarded. In this piece of research, an ordinary three dimensional reinforced concrete building is selected as case study. The building is located in an earthquake-prone region; however, it is designed according to seismic building codes. Yet, it is not shielded against abnormal loads, such as blasts. It is assumed that the building suffers a blast load, due to mechanical/thermal installation failure during or after intense seismic oscillations. These two critical incidents are regarded codependent and compatible. So the researchers developed scenarios and tried to assess different probabilities for each scenario and carried out an analysis to ensure if progressive collapse had set in or not. In the first step, two analysis models were used for each scenario; a non-linear dynamic time history analysis and a blast local dynamic analysis. In the second step, having the structural destructions of the first step in view, a pushdown analysis was carried out to determine the severity of progressive collapse and assess building robustness. Finally, the annual probability of structural collapse under simultaneous earthquake and blast loads was estimated and offered.

关键词： gas blast pushdown analysis progressive collapse annual probability of structural collapse 3D model of structure

Oxidative desulfurization of model and real oil samples using Mo supported on hierarchical alumina–silica: Process optimization by Box–Behnken experimental design

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Chinese Journal of Chemical Engineering 2019年第11期27卷 2759-2770页

作者： Nasim Ghorbani gholamreza Moradi Catalyst Research Center Department of Chemical EngineeringFaculty of EngineeringRazi UniversityKermanshahIran

The catalytic performance of Mo supported on hierarchical alumina–silica(Si/Al = 15) with Mo loadings of 3, 6 and 15 wt% was investigated for the oxidative desulfurization(ODS) of model and real oil samples. Hierarchical alumina–silica(h Al–Si) was synthesized by economical and ecofriendly silicate-1 seed-induced route using cetyltrimethylammonium bromide(CTAB) as mesoporogen. The effect of CTAB on the structure of catalyst was studied by characterization techniques. The results revealed that 6%Mo/h Al–Si had the highest sulfur removal compared to the other catalyst loadings. The effect of operating parameters was evaluated using Box–Behnken experimental design. The optimal desulfurization conditions with the 6%Mo/h Al–Si catalyst were determined at oxidation temperature of 67 ℃, oxidation time of 42 min, H2O2/S molar ratio of 8 and catalyst dosage of 0.008 g·ml^-1 for achieving a conversion of 95%. Under optimal conditions, different sulfur-containing compounds with initial concentration of 1000 ppm, Dibenzothiophene(DBT), Benzothiophene(BT) and Thiophen(Th), showed the catalytic oxidation reactivity in the order of DBT > BT>Th. According to the regeneration experiments, the 6%Mo/h Al–Si catalyst was reused 4 times with a little reduction in the performance. Also, the total sulfur content of gasoline and diesel after ODS process reached 156.6 and 4592.2 ppm, respectively.

关键词： Oxidative desulfurization Hierarchical alumina–silica Silicate-1 seed-induced route Box–Behnken experimental design

Experimental and numerical analysis of beam to column joints in steel structures

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Frontiers of Structural and Civil Engineering 2018年第4期12卷 642-661页

作者： gholamreza ABDOLLAHZADEH Seyed Mostafa SHABANIAN Faculty of Civil Engineering Babol Noshirvani University of TechnologyBabolIran

The behaviors such as extreme non-elastic response, constant changes in roughness and resistance, as well as formability under extreme loads such as earthquakes are the primary challenges in the modeling of beam-to-column connections. In this research, two modeling methods including mechanical and neural network methods have been presented in order to model the complex hysteresis behavior of beam-to-column connections with flange plate. First, the component-based mechanical model will be introduced in which every source of transformation has been shown only with geometrical and material properties. This is followed by the investigation of a neural network method for direct extraction of information out of experimental data. For the validation of behavioral curves as well as training of the neural network, the experiments were carried out on samples with real dimensions of beam-to-column connections with flange plate in the laboratory. At the end, the combinational modeling framework is presented. The comparisons reveal that the combinational modeling is able to display the complex narrowed hysteresis behavior of the beam-to-column connections with flange plate. This model has also been successfully employed for the prediction of the behavior of a newly designed connection.

关键词： beam to column connections experiments component method neural network model combinational modeling

Synthesis of boron nitride nanorod and its performance as a metalfree catalyst for oxidative desulfurization of diesel fuel

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Chinese Journal of Chemical Engineering 2024年第4期68卷 120-132页

作者： Tanaz Ghanadi gholamreza Moradi Alimorad Rashidi Catalyst Research Center Faculty of Chemical and Petroleum EngineeringRazi UniversityKermanshahIran Nanotechnology Research Center Research Institute of Petroleum Industry(RIPI)TehranIran

In order to reduce the sulfur compounds in diesel fuel,boron nitride(BN)has been used as a novel metal-free catalyst in the present *** nanocatalyst was synthesized via template-free approach followed by heating treatment at 900℃ in nitrogen atmosphere that the characteristics of the sample were identified by the X-ray diffraction,Fourier-transform infrared spectroscopy,Raman spectroscopy,field emission scanning electron microscopy,transmission electron microscopy,atomic force microscopy,and N2 adsorption-desorption *** results of structural and morphological analysis represented that BN has been successfully *** efficacy of the main operating parameters on the process was studied by using response surface methodology based on the Box-Behnken design *** prepared catalyst showed high efficiency in oxidative desulfurization of diesel fuel with initial sulfur content of 8040 mg·kg^(-1)*** statistical analysis,a significant quadratic model was obtained to predict the sulfur removal as a function of efficient *** maximum efficiency of 72.4%was achieved under optimized conditions at oxidant/sulfur molar ratio of 10.2,temperature of 71℃,reaction time of 113 min,and catalyst dosage of 0.36 ***,the reusability of the BN was studied,and the result showed little reduction in activity of the catalyst after 10 times ***,a plausible mechanism was proposed for oxidation of sulfur compounds on the surface of the *** present study shows that BN materials can be selected as promising metal-free catalysts for desulfurization process.

关键词： Desulfurization Boron nitride(BN)nanostructure Experimental design BoxeBehnken