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Synoptic-Thermodynamic Analysis of Pervasive Hailstorm Case Study: Tehran, March 30, 2015

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Journal of Geoscience and Environment Protection 2017年第9期5卷 155-175页

作者： mahmoud ahmadi Farzaneh Jafari Tayebeh Akbari Azirani Abbasali Dadashiroudbari Shahid Beheshti University Tehran Iran

The objective here is to assess the atmospheric evaluations with respect to the perilous hailstorm phenomenon in Tehran. To accomplish this study, the available data regarding 9 (WW) present weather codes that reveal the hailstorm phenomenon with different intensities in 3 hrs observations for 6 meteorological stations of Tehran and vicinity for the period between 1985-2015 are applied. It is revealed that hail occurrence in Tehran is at its maximum in transition seasons of spring and fall between the hrs. 6 - 18 (UTC). It is found that the instability indexes intensify in the afternoon with a higher atmospheric flotation indicative of the possibility in occurrence of thunder hailstorm. Synoptic assessments point to the fact that the synoptic pattern created this thunder storm due to expansion of two: low-pressure cores over Arabia and North-Europe and the cold high-pressure over South Russia with a NS orientation have developed an intense pressure gradient over Tehran province. The study area being located at the left exit of sub-tropical jet stream has made a Baroclinic atmosphere condition on Tehran province. Access to great humidity resources of Mediterranean and Black seas and a drastic decrease of temperature at the upper level of the cloud verifies the hail occurrence on March 30th of 2015 in Tehran.

关键词： Hail Thermodynamic Indexes Synoptic Blocking Systems Tehran Province

Context-dependency in medicine:how neuronal excitability influences the impact of dopamine on cognition

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Neural Regeneration Research 2025年第11期20卷 3225-3226页

作者： Mahboubeh ahmadi Nahid Rouhi Javad Mirnajafi-Zadeh Bechara J.Saab Department of Physiology Faculty of Medical SciencesTarbiat Modares UniversityTehranIran Mobio Interactive Pte.Ltd. SingaporeRepublic of Singapore

Dopamine,often termed the"feel-good"neurotransmitter,plays a crucial role in myriad physiological and psychological brain *** dopamine is primarily associated with pleasure,reward,and motivation,its effects can be quite complex;and this complexity is further compounded when examining how dopamine functions in typical versus disease-affected neural *** pa rticula r,epilepsy,characte rized by heightened brain excitability,is linked to cognitive dysfunction,and dopamine is implicated in elements of both its pathology and *** has been successful in describing the synaptic abnormalities believed to contribute to memory issues in epilepsy,aiding in the search for effective therapies for what persists as a major medical issue.

关键词： dopamine epilepsy primarily

Nano-microbubble flotation of fine and ultrafine chalcopyrite particles

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International Journal of Mining Science and Technology 2014年第4期24卷 559-566页

作者： ahmadi Rahman Khodadadi Darban Ahmad Abdollahy mahmoud Fan Maoming Department of Mineral Processing Engineering Tarbiat Modares University EFD Eriez Manufacturing Co.

As is well known to mineral processing scientists and engineers, fine and ultrafine particles are difficult to float mainly due to the low bubble-particle collision efficiencies. Though many efforts have been made to improve flotation performance of fine and ultrafine particles, there is still much more to be done. In this paper, the effects of nano-microbubbles （nanobuhbles and microbubbles） on the flotation of fine （-38 ＋ 14.36 μm） and ultrafine （-14.36 ＋ 5μm） chalcopyrite particles were investigated in a laboratory scale Denver flotation cell. Nano-microbubbles were generated using a specially-designed nano- microbubble generator based on the cavitation phenomenon in Venturi tubes. In order to better under- stand the mechanisms of nano-microbubble enhanced froth flotation of fine and ultrafine chalcopyrite particles, the nano-microbubble size distribution, stability and the effect of frother concentration on nano- bubble size were also studied by a laser diffraction method. Comparative flotation tests were performed in the presence and absence of nano-microbubbles to evaluate their impact on the fine and ultrafine chalcopyrite particle flotation recovery. According to the results, the mean size of nano-microbubbles increased over time, and decreased with increase of frother concentration. The laboratory-scale flotation test results indicated that flotation recovery of chalcopyrite fine and ultrafine particles increased by approximately 16-21% in the presence of nano-microbubbles, depending on operating conditions of the process. The presence of nano-microbubbles increased the recovery of ultrafine particles （-14.36 ＋ 5 μm） more than that of fine particles （-38 ＋ 14.36 μm）. Another major advantage is that the use of nano-microbubbles reduced the collector and frother consumptions by up to 75% and 50%, respectively.

关键词： Nanobubbles Nano-microbubble Bubble size distribution Chalcopyrite Froth flotation Fine particles

Quantum transport through a Z-shaped silicene nanoribbon

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Chinese Physics B 2017年第4期26卷 415-419页

作者： A ahmadi Fouladi Department of Physics Sari BranchIslamic Azad UniversitySariIran

In this work,the electronic transport properties of Z-shaped silicene nanoribbon（ZsSiNR） structure are *** calculations are based on the tight-binding model and Green＇s function method in Landauer-Biittiker formalism,in which the electronic density of states（DOS）,transmission probability,and current-voltage characteristics of the system are calculated,*** is shown that the geometry of the ZsSiNR structure can play an important role to control the electron transport through the *** is observed that the intensity of electron localization at the edges of the ZsSiNR decreases with the increase of the spin-orbit interaction（SOI） ***,the semiconductor to metallic transition occurs by increasing the SOI *** present theoretical results may be useful to design silicene-based devices in nanoelectronics.

关键词： Z-shaped silicene nanoribbon electronic transport Green's function method spin–orbit interaction

Optimal design of double-layer barrel vaults using genetic and pattern search algorithms and optimized neural network as surrogate model

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Frontiers of Structural and Civil Engineering 2023年第3期17卷 378-395页

作者： Reza JAVANMARDI Behrouz ahmadi-NEDUSHAN Department of Civil Engineering Yazd UniversityYazd 89195Iran

This paper presents a combined method based on optimized neural networks and optimization algorithms to solve structural optimization *** main idea is to utilize an optimized artificial neural network(OANN)as a surrogate model to reduce the number of computations for structural ***,the OANN is trained ***,the main optimization problem is solved using the OANN and a population-based *** algorithms considered in this step are the arithmetic optimization algorithm(AOA)and genetic algorithm(GA).Finally,the abovementioned problem is solved using the optimal point obtained from the previous step and the pattern search(PS)*** evaluate the performance of the proposed method,two numerical examples are *** the first example,the performance of two algorithms,OANN+AOA+PS and OANN+GA+PS,is *** the GA reduces the elapsed time by approximately 50%compared with using the *** show that both the OANN+GA+PS and OANN+AOA+PS algorithms perform well in solving structural optimization problems and achieve the same optimal ***,the OANN+GA+PS algorithm requires significantly fewer function evaluations to achieve the same accuracy as the OANN+AOA+PS algorithm.

关键词： optimization surrogate models artificial neural network SAP2000 genetic algorithm

Moisture-dependent physical properties of barley grains

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International Journal of Agricultural and Biological Engineering 2009年第4期2卷 84-91页

作者： mahmoud Tavakoli Hamed Tavakoli Ali Rajabipour Hojat ahmadi Seyed Mohammad Taghi Gharib-Zahedi Department of Food Science and Technology Faculty of AgricultureUniversity of ZabolZabolIran Department of Agricultural Machinery Engineering Faculty of Agricultural Engineering&TechnologyUniversity of TehranP.O.Box 4111Karaj 31587-77871Iran Department of Food Science and Engineering Faculty of Agricultural Engineering&TechnologyUniversity of TehranKarajIran

Designing equipment for processing,sorting,sizing and other post-harvest operations of agricultural products requires information about their physical *** study was carried out to evaluate the effect of moisture content on some physical properties of barley *** levels of moisture content ranging from 7.34%to 21.58%(d.b.)were *** average length,width,thickness,arithmetic mean diameter,geometric mean diameter,thousand grain mass,sphericity,surface area and repose angle increased from 8.91 to 9.64 mm,3.30 to 3.74 mm,2.58 to 2.98 mm,4.93 to 5.45 mm,4.23 to 4.75 mm,44.48 to 51.30 g,47.55%to 49.35%,56.66 to 71.09 mm2 and 31.16°to 36.90°,respectively,as moisture content increased from 7.34%to 21.58%(d.b.).The bulk density,true density and porosity were found to decrease with increasing moisture *** static friction coefficient of the grains increased linearly against various surfaces(plywood,glass and galvanized iron sheet)as the moisture content *** all moisture content,the maximum friction was offered by plywood,followed by galvanized iron sheet and glass surface.

关键词： barley moisture content angle of repose coefficient of friction

An efficient two-stage approach for structural damage detection using meta-heuristic algorithms and group method of data handling surrogate model

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Frontiers of Structural and Civil Engineering 2020年第4期14卷 907-929页

作者： Hamed FATHNEJAT Behrouz ahmadi-NEDUSHAN Department of Civil Engineering Yazd UniversityYazd 89195-741Iran

In this study,the performance of an efficient two-stage methodology which is applied in a damage detection system using a surrogate model of the structure has been *** the first stage,in order to locate the damage accurately,the performance of the modal strain energy based index for using different numbers of natural mode shapes has been evaluated using the confusion *** the second stage,to estimate the damage extent,the sensitivity of most used modal properties due to damage,such as natural frequency and flexibility matrix is compared with the mean normalized modal strain energy(MNMSE)of suspected damaged ***,a modal property change vector is evaluated using the group method of data handling(GMDH)network as a surrogate model during damage extent estimation by optimization algorithm;in this part of methodology,the performance of the three popular optimization algorithms including particle swarm optimization(PSO),bat algorithm(BA),and colliding bodies optimization(CBO)is examined and in this regard,root mean square deviation(RMSD)based on the modal property change vector has been proposed as an objective ***,the effect of noise in the measurement of structural responses by the sensors has also been ***,in order to achieve the most generalized neural network as a surrogate model,GMDH performance is compared with a properly trained cascade feed-forward neural network(CFNN)with log-sigmoid hidden layer transfer *** results indicate that the accuracy of damage extent estimation is acceptable in the case of integration of PSO and ***,the GMDH model is also more efficient and mimics the behavior of the structure slightly better than CFNN model.

关键词： two-stage method modal strain energy surrogate model GMDH optimization damage detection

Effects of Yttrium Addition on Microstructure, Hardness and Resistance to Wear and Corrosive Wear of TiNi Alloy

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Journal of Materials Science & Technology 2011年第9期27卷 851-855页

作者： Hojat ahmadi Meisam Nouri Faculty of Biosystems Engineering University of Tehran Department of Materials Engineering Tarbiat Modares University

TiNi alloy has a high resistance to wear and could be an excellent candidate for various tribological applications. In this paper, it was demonstrated that by addition of yttrium, hardness properties and resistance to wear and corrosive wear of TiNi alloy were improved. New yttrium rich regions were formed in microstructure of TiNi alloy. The improved properties of this alloy by the yttrium addition could be attributed to the formation of these regions. The results showed that there was an optimum content for addition of yttrium between 2% and 5% （in wt%）, and above this content the improvement in properties of TiNi became minor.

关键词： Yttrium TiNi Mechanical behaviour Wear Corrosive wear Microstructure

Photoactive area modification in bulk heterojunction organic solar cells using optimization of electrochemically synthesized ZnO nanorods

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Chinese Physics B 2015年第11期24卷 422-427页

作者： Mehdi ahmadi Sajjad Rashidi Dafeh Department of Physics Faculty of Science Vali-e-Asr University of Rafsanjan

In this work, ZnO nanorod arrays grown by an electrochemical deposition method are investigated. The crucial parameters of length, diameter, and density of the nanorods are optimized over the synthesize process and nanorods growth time. Crystalline structure, morphologies, and optical properties of ZnO nanorod arrays are studied by different techniques such as x-ray diffraction, scanning electron microscope, atomic force microscope, and UV-visible transmission spectra. The ZnO nanorod arrays are employed in an inverted bulk heterojunction organic solar cell of Poly （3-hexylthiophene）：[6- 6] Phenyl-（6） butyric acid methyl ester to introduce more surface contact between the electron transporter layer and the active layer. Our results show that the deposition time is a very important factor to achieve the aligned and uniform ZnO nanorods with suitable surface density which is required for effective infiltration of active area into the ZnO nanorod spacing and make a maximum interfacial surface contact for electron collection, as overgrowing causes nanorods to be too dense and thick and results in high resistance and lower visible light transmittance. By optimizing the thickness of the active layer on top of ZnO nanorods, an improved efficiency of 3.17% with a high FF beyond 60% was achieved.

关键词： electrochemical deposition density-controlled ZnO nanorods inverted polymer solar cells active area modification