Search for: ghasemi--a
Total 26 records
Modeling and parallel computation of the non-linear interaction of rigid bodies with incompressible multi-phase flow, Article Computers and Mathematics with Applications ; Volume 72, Issue 4 , 2016 , Pages 1055-1065 ; 08981221 (ISSN) ; Ghasemi, A. M ; Nikbakhti, R ; Ghasemi, A. R ; Hedayati, F ; Sharif University of Technology
A computational tool is developed to capture the interaction of solid object with two-phase flow. The full two-dimensional Navier–Stokes equations are solved on a regular structured grid to resolve the flow field. The level set and the immersed boundary methods are used to capture the free surface of a fluid and a solid object, respectively. A two-step projection method along with Multi-Processing (OpenMP) is employed to solve the flow equations. The computational tool is verified based on numerical and experimental data with three scenarios: a cylinder falling into a rectangular domain due to gravity, transient vertical oscillation of a cylinder by releasing above its equilibrium position,...
High content of boride-forming elements in in617 nickel-based superalloy enables short isothermal solidification time during transient liquid phase bonding, Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 51, Issue 11 , 2020 , Pages 5715-5724 ; Ghasemi, A ; Pouranvari, M ; Sharif University of Technology
Isothermal solidification stage during transient liquid phase bonding is the key to preclude intermetallic phase formation during solidification of the liquid phase. The rate of isothermal solidification is controlled by solid-state diffusion. Therefore, the bonding time required to complete isothermal solidification is generally long. This paper reports a very short isothermal solidification time for transient liquid phase bonding of IN617 solid solution nickel-based superalloy using a boron-containing filler metal. A eutectic-free bond with limited grain growth in the base material with high shear strength is achievable by utilizing a short (i.e., 5 minutes) thermal bonding strategy. The...
Enhanced mechanical properties of martensitic stainless steels resistance spot welds enabled by in situ rapid tempering, Article Science and Technology of Welding and Joining ; Volume 25, Issue 2 , 2020 , Pages 119-126 ; Aghajani, H ; Ghasemi, A ; Sharif University of Technology
Taylor and Francis Ltd 2020
Resistance spot weldability of martensitic stainless steels is impaired by the formation of brittle martensite in the fusion zone (FZ). In this paper, in situ rapid tempering via applying a second pulse current after a first melting/solidification pulse during resistance spot welding of AISI 420 martensitic stainless steel sheets was used as a pathway to enhance the toughness of the FZ. By using proper second pulse conditions, the FZ with reduced hardness can be generated which is featured by a decomposed martensitic structure with nano-sized carbide precipitations. The improved toughness as a consequence of this modified microstructure resulted in remarkable enhancement of the peak load and...
Article Scientia Iranica ; Volume 11, Issue 4 , 2004 , Pages 386-391 ; 10263098 (ISSN) ; Ghasemi, A ; Sharif University of Technology
Sharif University of Technology 2004
In this paper, the effect of morphology, size and volume fraction of the most important microstructural constituents of cast A356 aluminum alloy on its main mechanical properties has been studied. The investigated variables consist of Dendrite Arm Spacing (DAS) of α aluminum phases, spheroicity of silicon particles in eutectic areas and 2-D micro porosity areas. The variations of Quality Index (Qi) with DAS and spheroicity of eutectic silicon particles follow a linear relationship. For the micro-porosity area of a polished section of the studied samples, two linear relationships were found, one for values less than 1.25% and another for higher values. As the basis for a quantitative analysis...
Article 2006 Spring Technical Conference of the ASME Internal Combustion Engine Division, Aachen, 7 May 2006 through 10 May 2006 ; 2006 , Pages 109-115 ; 15296598 (ISSN) ; 0791842061 (ISBN); 9780791842065 (ISBN) ; Mozafari, A. A ; Ghasemi, A ; Sharif University of Technology
The monolithic catalytic converter still is the main pollution control device for modern vehicles in order to reach the ever-increasing legislative demands for low emission standards. The catalytic converters require a large expansion from the exhaust pipe to the front face of the monolith. Unfortunately, packaging constraints often do not permit the use of long diffusers. Hence, flow separation within the diffuser leads to a non-uniform flow distribution across the monolith. A uniform flow distribution at the inlet monolith face is favorable for the conversion efficiency as well as the durability of the catalytic converter. Therefore the main problem is to optimize the flow distribution at...
Effect of Ti-Zn substitution on structural, magnetic and microwave absorption characteristics of strontium hexaferrite, Article Journal of Alloys and Compounds ; Vol. 583, issue , 2014 , p. 325-328 ; Ghasemi, A ; Nemati, A ; Azami Ghadikolaei, M ; Paimozd, E ; Sharif University of Technology
SrFe12-xTix/2Zn x/2O19 (x = 0-2.5) powders were synthesized by use of chlorides through co-precipitation method. The obtained powders were then milled by high energy ball mill to crash hard agglomerates and achieve nanoparticles. In order to evaluate microwave absorption versus frequency, composites including ferrite, as a filler, and matrix of polyvinylchloride (PVC) with weight ratio of 70% ferrite were prepared. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), vibrating sample magnetometer (VSM) and vector network analyzer (VNA) were employed to study the structural, magnetic and microwave absorption properties...
Article Transactions of the Indian Institute of Metals ; Volume 68, Issue 5 , October , 2015 , Pages 991-998 ; 09722815 (ISSN) ; Ghasemi, A ; Pouraliakbar, H ; Jandaghi, M. R ; Sharif University of Technology
Springer India 2015
Dissimilar Al/Cu joints were produced through simple cold compression technique. The influence of different reductions (40, 53 and 66 %) on the joint strength was studied. Also, the effect of heat treatment on the joints’ mechanical characteristics was investigated using a modified miniature shear test. Microscopical examinations by means of optical and scanning electron microscopes were conducted and results confirmed that acceptable joints produced through 53 and 66 % deformations. According to the shear test results, it was revealed that post-weld heat treatment influenced the joint’s strength and caused strength enhancement in the samples which were not subjected to annealing prior to...
Article Journal of Materials Science: Materials in Electronics ; Volume 27, Issue 2 , 2016 , Pages 1901-1905 ; 09574522 (ISSN) ; Ghasemi, A ; Ghadi Kolaei, M. A ; Nemati, A ; Paimozd, E ; Sharif University of Technology
Springer New York LLC
Strontium hexaferrites with the composition of SrFe12−xTix/2Znx/2O19 (x = 0–2.5 in steps of 0.5) were synthesized using chlorides by means of co-precipitation route. The structural, magnetic and microwave absorption properties of the samples were surveyed. The results confirmed that the magnetoplumbite single phase was obtained for all samples and the hexagonal particles dispersed within size range of 1–2 µm. With increasing amount of dopant, coercivity decreased from 5640 to 1486 Oe while the maximum saturation magnetization was 63 emu/g and belonged to x = 0.5. The reflection loss results denoted that the prepared composites had excellent microwave absorption properties and the maximum...
A comprehensive experimental and numerical study on redistribution of residual stresses by shot peening, Article Materials and Design ; Volume 90 , 2016 , Pages 478-487 ; 02641275 (ISSN) ; Ghasemi, A ; Farrahi, G. H ; Sherafatnia, K ; Sharif University of Technology
Elsevier Ltd 2016
Shot peening is one of the most effective surface strengthening treatment technologies in which compressive residual stresses are induced beneath the specimen surface. Effects of various factors on the distribution of residual stress profile induced by shot peening have been investigated by many researchers. However, initial residual stresses are one of the important factors which affect the shot peening residual stress.This study is aimed to present comprehensive numerical and experimental study on the effect of initial residual stresses on the shot peened specimen. Initial residual stresses were induced using a four-point bending rig and grinding. Incremental center hole drilling (ICHD)...
Experimental measurement and analytical determination of shot peening residual stresses considering friction and real unloading behavior, Article Materials Science and Engineering A ; Volume 657 , 2016 , Pages 309-321 ; 09215093 (ISSN) ; Farrahi, G. H ; Mahmoudi, A. H ; Ghasemi, A ; Sharif University of Technology
Elsevier Ltd 2016
This paper presents an analytical model to predict the residual stress distribution induced by Shot peening. The analytical approach is based on the work of Shen and Atluri (2006)  with some modifications. The modifications are related to the elasto-plastic unloading of shot impingements, friction coefficient effect and the fraction of kinetic energy transmitted to the treated material. In order to predict more realistic residual stresses, the elasto-plastic unloading phase of shot impacts is modeled using two nonlinear kinematic hardening models considering the Bauschinger effect. Moreover, the effect of the Coulomb friction between target surface and shots is evaluated. For this...
Parallelized numerical modeling of the interaction of a solid object with immiscible incompressible two-phase fluid flow, Article Engineering Computations (Swansea, Wales) ; Volume 34, Issue 3 , 2017 , Pages 709-724 ; 02644401 (ISSN) ; Nikbakhti, R ; Ghasemi, A ; Hedayati, F ; Malvandi, A ; Sharif University of Technology
Purpose - A numerical method is developed to capture the interaction of solid object with two-phase flow with high density ratios. The current computational tool would be the first step of accurate modeling of wave energy converters in which the immense energy of the ocean can be extracted at low cost. Design/methodology/approach - The full two-dimensional Navier-Stokes equations are discretized on a regular structured grid, and the two-step projection method along with multi-processing (OpenMP) is used to efficiently solve the flow equations. The level set and the immersed boundary methods are used to capture the free surface of a fluid and a solid object, respectively. The full...
Temperature-responsive smart nanocarriers for delivery of therapeutic agents: applications and recent advances, Article ACS Applied Materials and Interfaces ; Volume 8, Issue 33 , 2016 , Pages 21107-21133 ; 19448244 (ISSN) ; Sahandi Zangabad, P ; Ghasemi, A ; Amiri, M ; Bahrami, M ; Malekzad, H ; Ghahramanzadeh Asl, H ; Mahdieh, Z ; Bozorgomid, M ; Ghasemi, A ; Rahmani Taji Boyuk, M. R ; Hamblin, M. R ; Sharif University of Technology
American Chemical Society 2016
Smart drug delivery systems (DDSs) have attracted the attention of many scientists, as carriers that can be stimulated by changes in environmental parameters such as temperature, pH, light, electromagnetic fields, mechanical forces, etc. These smart nanocarriers can release their cargo on demand when their target is reached and the stimulus is applied. Using the techniques of nanotechnology, these nanocarriers can be tailored to be target-specific, and exhibit delayed or controlled release of drugs. Temperature-responsive nanocarriers are one of most important groups of smart nanoparticles (NPs) that have been investigated during the past decades. Temperature can either act as an external...
Article BIOSIGNALS 2012 - Proceedings of the International Conference on Bio-Inspired Systems and Signal Processing ; 2012 , Pages 32-37 ; 9789898425898 (ISBN) ; Ghasemi, A ; Tavanaei, M ; Sameti, H ; Manzuri, M. T ; Inst. Syst. Technol. Inf., Control Commun. (INSTICC) ; Sharif University of Technology
A classifier based on Support Vector Data Description (SVDD) is proposed for spoken digit recognition. We use the Mel Frequency Discrete Wavelet Coefficients (MFDWC) and the Mel Frequency cepstral Coefficients (MFCC) as the feature vectors. The proposed classifier is compared to the HMM and results are promising and we show the HMM and SVDD classifiers have equal accuracy rates. The performance of the proposed features and SVDD classifier with several kernel functions are evaluated and compared in clean and noisy speech. Because of multi resolution and localization of the Wavelet Transform (WT) and using SVDD, experiments on the spoken digit recognition systems based on MFDWC features and...
Article Tumor Biology ; Volume 39, Issue 6 , 2017 ; 10104283 (ISSN) ; Mostafaei, S ; Yari, K ; Ghasemi, A ; Chenar, H. M ; Moghoofei, M ; Sharif University of Technology
Human parvovirus B19 (B19) is a small, non-enveloped virus and belongs to Parvoviridae family. B19 persists in many tissues such as thyroid tissue and even thyroid cancer. The main aim of this study was to determine the presence of B19, its association with increased inflammation in thyroid tissue, and thus its possible role in thyroid cancer progression. Studies have shown that virus replication in non-permissive tissue leads to overexpression of non-structural protein and results in upregulation of proinflammatory cytokines such as interleukin 6 and tumor necrosis factor alpha. A total of 36 paraffin-embedded thyroid specimens and serum were collected from patients and 12 samples were used...
Nanocaged platforms: Modification, drug delivery and nanotoxicity. Opening synthetic cages to release the tiger, Article Nanoscale ; Volume 9, Issue 4 , 2017 , Pages 1356-1392 ; 20403364 (ISSN) ; Karimi, M ; Mehdizadeh, F ; Malekzad, H ; Ghasemi, A ; Bahrami, S ; Zare, H ; Moghoofei, M ; Hekmatmanesh, A ; Hamblin, M. R ; Sharif University of Technology
Royal Society of Chemistry 2017
Nanocages (NCs) have emerged as a new class of drug-carriers, with a wide range of possibilities in multi-modality medical treatments and theranostics. Nanocages can overcome such limitations as high toxicity caused by anti-cancer chemotherapy or by the nanocarrier itself, due to their unique characteristics. These properties consist of: (1) a high loading-capacity (spacious interior); (2) a porous structure (analogous to openings between the bars of the cage); (3) enabling smart release (a key to unlock the cage); and (4) a low likelihood of unfavorable immune responses (the outside of the cage is safe). In this review, we cover different classes of NC structures such as virus-like...
MicroRNAs 29, 150, 155, 223 level and their relation to viral and immunological markers in HIV-1 infected naive patients, Article Future Virology ; Volume 13, Issue 9 , 2018 , Pages 637-645 ; 17460794 (ISSN) ; Bokharaei Salim, F ; Esghaei, M ; Keyvani, H ; Honardoost, M ; Mostafaei, S ; Ghasemi, A ; Tavakoli, A ; Javanmard, D ; Babaei, F ; Garshasbi, S ; Monavari, S. H ; Sharif University of Technology
Aim: The aim of this study was to assess the relationship between microRNAs and viral and immunological markers in HIV-1 infection. Materials & methods: The expression level of miRNAs was evaluated in 60 HIV-1 patients and 20 healthy controls using real-time PCR assays. Results: The results showed that among all miRNAs, miR-29 and miR-150 were significantly downregulated in HIV-1 patients compared with healthy controls, while miR-155 and miR-223 were significantly upregulated compared with healthy controls (p < 0.001 for all comparisons). Conclusion: The mentioned miRNAs seem to influence the clinical progression of HIV-1 infection in naive patients. Moreover, determining the profiles of...
Bacterial components as naturally inspired nano-carriers for drug/gene delivery and immunization: set the bugs to work?, Article Biotechnology Advances ; Volume 36, Issue 4 , 2018 , Pages 968-985 ; 07349750 (ISSN) ; Moghoofei, M ; Mirkiani, S ; Ghasemi, A ; Rabiee, N ; Hadifar, S ; Beyzavi, A ; Karimi, M ; Hamblin, M. R ; Sharif University of Technology
Elsevier Inc 2018
Drug delivery is a rapidly growing area of research motivated by the nanotechnology revolution, the ideal of personalized medicine, and the desire to reduce the side effects of toxic anti-cancer drugs. Amongst a bewildering array of different nanostructures and nanocarriers, those examples that are fundamentally bio-inspired and derived from natural sources are particularly preferred. Delivery of vaccines is also an active area of research in this field. Bacterial cells and their components that have been used for drug delivery, include the crystalline cell-surface layer known as “S-layer” bacterial ghosts, bacterial outer membrane vesicles, and bacterial products or derivatives (e.g....
Article Clinical Respiratory Journal ; Volume 12, Issue 5 , 2018 , Pages 1787-1801 ; 17526981 (ISSN) ; Monavari, H. R ; Mostafaei, S ; Hadifar, S ; Ghasemi, A ; Babaei, F ; Kavosi, H ; Tavakoli, A ; Javanmard, D ; Esghaei, M ; Khodabandehlou, N ; Sharif University of Technology
Blackwell Publishing Ltd 2018
Objective: This systematic review and meta-analysis was performed to determine the prevalence rate of influenza virus from different parts of Middle East region, and present an overall relative frequency (RF) for this region. Methods: The authors performed a systematic literature review from several reliable databases such as PubMed, ISI Web of Science and Scopus during 2000–2016. Furthermore, the keywords of this research were ‘Influenza’, ‘Subtype’, ‘Seroprevalence’, ‘Incidence’, ‘Seroepidemiology’, ‘H1N1’, ‘H3N2’, ‘H5N1’, ‘H9N2’, ‘Middle-East’ and ‘Meta-analysis’. The reported data were selected according to inclusion and exclusion criteria. Results: The authors selected 71 studies out of...
Article BMC Cancer ; Volume 19, Issue 1 , 2019 ; 14712407 (ISSN) ; Mostafaei, S ; Etemadi, A ; Ghasemi, A ; Payandeh, M ; Hadifar, S ; Norooznezhad, A. H ; Kazemnejad, A ; Moghoofei, M ; Sharif University of Technology
BioMed Central Ltd 2019
Background: Breast cancer is currently the most common neoplasm diagnosed in women globally. There is a growing body of evidence to suggest that human papillomavirus (HPV) infection may play a key role in invasiveness of breast cancer. The aim of this study was to determine the presence of HPV in patients with breast cancer and its possible association with cancer progression. Methods: Breast specimens were collected from 72 patients with breast cancer and 31 healthy controls. The presence of HPV was investigated by polymerase chain reaction (PCR) and genotyping was performed for positive cases. We also evaluated the viral factors such as E6, E2, and E7 in HPV positive cases. Enzyme-linked...
Recent developments in graphene and graphene oxide: properties, synthesis, and modifications: a review, Article ChemistrySelect ; Volume 5, Issue 33 , 2020 , Pages 10200-10219 ; Abbaspour, S ; Abdolahi Sadatlu, M. A ; Mirkiani, S ; Ghasemi, A ; Hoseini Ghahfarokhi, M ; Mozaffari, N ; Karimi, M ; Hamblin, M. R ; Sharif University of Technology
Graphene was first discovered as a sheet structure mechanically exfoliated from a block of graphite, but in recent years researchers have extended their investigations into this two-dimensional carbon nanostructure. Various applications of graphene-based materials have included electronics, photonics, optoelectronics, sensors, and drug / gene delivery systems. These single atom carbon layers have the potential to be formed in different morphologies e. g., quantum dots, nanosheets, and nanoparticles, which can be tailored to achieve new breakthrough innovations. Nowadays, the utilization of graphene-based nanomaterials in medicine is a hot research topic. This review discusses the structure,...