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51.
Mohamadi Arash Shahgholi Majid Ashenai Ghasemi Faramarz 《International Journal of Mechanics and Materials in Design》2022,18(1):125-154
International Journal of Mechanics and Materials in Design - The focus of the present paper is on investigating the nonlinear dynamics of the axially moving FG-CNTRC shells with different... 相似文献
52.
Behnam Akhoundi Mojtaba Nabipour Faramarz Hajami Diana Shakoori 《Polymer Engineering and Science》2020,60(5):979-987
Fused deposition modeling (FDM) is the trendiest three-dimensional (3D) printing method among additive manufacturing technologies. In this process, the final parts are constructed through layer-by-layer adhesion of thermoplastic polymers. Amorphous thermoplastic polymers have better printability compared to semicrystalline ones; so, they are most popular with FDM users. Generally, the overall mechanical properties of FDM 3D printed parts are weaker in comparison to the traditional methods (such as injection molding) due to the weak bonds between the deposited rasters and layers. Therefore, the introduction of new materials with higher mechanical properties and easy printing process of the semicrystalline polymers has always been challenging to progress the mechanical properties of the products. In this study by the FDM process, the effect of nozzle temperature and heat treatment (annealing) on the mechanical properties of high-temperature polylactic acids is investigated. The increase in the nozzle temperature develops the rasters and layers bonding, and the heat treatment of the parts after printing rises the crystallinity percentage, which is crucial for the improvement of mechanical properties. Experimental results show that an increase in the nozzle temperature raises the tensile strength and modulus to 65.7 MPa and 4.97 GPa, respectively. Furthermore, the heat treatment process increases the tensile strength and modulus up to 67.4 MPa and 5.65 GPa. The final tensile modulus values are the highest ones reported for pure materials printed by the FDM process. POLYM. ENG. SCI., 60:979–987, 2020. © 2020 Society of Plastics Engineers 相似文献
53.
Experimental validation of a deep neural network—Sparse representation classification ensemble method 下载免费PDF全文
Milad Fallahian Faramarz Khoshnoudian Saeid Talaei Viviana Meruane Fariba Shadan 《The Structural Design of Tall and Special Buildings》2018,27(15)
In the current study, a new pattern recognition‐based damage detection technique is developed using the frequency response function of the structure. Principal component analysis is employed as an authoritative feature extraction method for dimensional reduction of the measured frequency response function data and constructing distinct feature patterns. Subsequently, as a novel approach, an ensemble of 2 powerful classifiers containing deep neural networks and couple sparse coding classification is utilized for damage prediction of the structure because there is no individual optimal classifier for all the problems. Verification of the proposed method is evaluated by an aluminum beam experimental setup besides a numerical 3D finite element model of a truss bridge. Damage detection results elucidate that the ensemble method decisions are much more accurate compared with the individual classifier decision. The proposed ensemble method verifies to be a novel, robust, and powerful damage detection process. 相似文献
54.
Faramarz Ashenai Ghasemi Sajjad Daneshpayeh Ismail Ghasemi Mohsen Ayaz 《Polymer Bulletin》2016,73(6):1741-1760
55.
Polyacrylonitrile nanofibers (PAN-nFs) were produced using the electrospinning method. Subsequently, the electrospun fibers were modified by diethylenetriamine to produce aminated polyacrylonitrile (APAN) nanofibers. Finally, the adsorbability of copper ions on the surface of the nanofibers was examined in an aqueous solution. Attenuated total internal reflection (ATIR) analysis confirmed the surface amination of the produced PAN-nFs. The grafting yield was calculated by the gravimetric method. The optimum condition was determined to yield the maximum grafting of amine groups to PAN with no losses in sample flexibility. Atomic absorption spectroscopy (AAS) was used to measure the copper ion concentration in the solution. Results indicate that the adsorption process in nanofibers is three times faster in comparison with microfibers. Moreover, the pH effect was studied based on the adsorption behavior of copper ions on the APAN nanofibers. In addition, thermodynamic parameters were calculated, revealing that the process was endothermic and demonstrating that randomness increased at the solid-solution interface during the process. The obtained enthalpy value indicates that the chelation of copper ions among the aminated polyacrylonitrile can be regarded as a chemical adsorption process. The adsorption data fit well with the Langmuir isotherm. The saturation adsorption capacity obtained from the Langmuir model for Cu(II) ions was 116.522 mg/g which is five times more than the reported value for APAN microfibers [S. Deng, R. Bai, J.P. Chen, Aminated polyacrylonitrile fibers for lead and copper removal, Langmuir,19 (2003)5058-5064]. Analysis using atomic force microscopy (AFM) showed that the surface roughness increased upon adsorption of the metal ion. Scanning electron microscopy (SEM) examination demonstrated that there were no cracks or sign of degradation on the surface after amination. 相似文献
56.
Pouya Rajaee Faramarz Ashenai Ghasemi Seyyed Ali Sajjadi Mohammad Fasihi 《应用聚合物科学杂志》2024,141(16):e55262
The increasing application of additive manufacturing (AM) technology across various sectors has sparked significant interest in characterizing 3D-printed components. An essential aspect of achieving fracture-resistant designs is gaining a comprehensive understanding of the fracture behavior exhibited by these components. While most studies have focused on linear-elastic fracture mechanics (LEFM), there is a lack of comprehensive studies on the post-yield fracture behavior (PYFM) of 3D-printed components. As a result, this study aims to fill this gap by investigating the impact of raster angle, a critical parameter influencing fracture properties and often leading to premature failures, on the fracture properties of fused deposition modeling (FDM) 3D printed acrylonitrile butadiene styrene (ABS) using essential work of fracture (EWF). Outcomes showed that by changing lay-ups from [90]5 to [0]5, the value of we or elastic work increased by nearly 306%. Further, the maximum and minimum values of the plastic work (βwp) were for [45/−45/45/−45/45] and [90]5 lay-ups, in order. By changing lay-ups from [90]5 to [45/−45/45/−45/45], the value of βwp increased by approximately 216%. In addition, the fractured surfaces of tested samples are also analyzed to provide insights into the dominant failure mechanisms for different raster angles. 相似文献
57.
Loss of hot ductility at the straightening stage of the continuous casting of high-strength low-alloy steel is attributed
to different microalloying elements, in particular, Nb. However, such elements are essential for the desired mechanical characteristics
of the final product. Since the chemistry cannot be altered to alleviate the problem, thermomechanical processing was studied
in order to improve the hot ductility. Two Nb-microalloyed steels, one also containing B, were examined. The thermal history
occurring in the continuous casting process was taken into account as well. First, it was noticed that the steel with B has
a higher hot ductility than the other after being subjected to in-situ melting followed by the thermal schedule. Grain boundary sliding was recognized as the failure mechanism. Then, the effect
of deformation applied in the vicinity of the δ→γ transformation, while the thermal schedule was being executed, was investigated. Such deformation appeared to improve the
hot ductility remarkably. Finally, the mechanism of such improvement in the hot ductility was elaborated. 相似文献
58.
Geochemical and Mineralogical Characterization of a Pyritic Waste Pile at the Anjir Tangeh Coal Washing Plant, Zirab, Northern Iran 总被引:3,自引:2,他引:1
Majid Shahhoseiny Faramarz Doulati Ardejani Seyed Ziaedin Shafaei Mohammad Noaparast Dariush Hamidi 《Mine Water and the Environment》2013,32(2):84-96
Coal washing at the Anjir Tangeh plant, in Zirab, northern Iran, has produced more than 1.5 Mt of coal wastes. These waste materials were geochemically and mineralogically characterised to guide development of an appropriate remediation scheme. Three vertical trenches up to 4 m deep were excavated from the coal waste pile surface and 25 solid samples were collected at 0.5 m intervals. The samples were analysed for total concentrations of 54 elements, paste pH, SO 4 ?2 , CO 3 ?2 , and HCO3 ?. The lowest pH values were measured at a depth of 0.3 m. The upper portion (1 m) of one profile was moderately oxidised, while oxidation in the other two profiles did not extend more than 0.8 and 0.5 m beneath the pile surface. The waste piles have low acid-producing potential (15–21.87 kg CaCO3/t) and high values of acid-neutralizing potential (0.06–96.2 kg CaCO3/t). Fe, Al, S, Na, Mn, Pb, Zn, Cd, and Ag increased with increasing depth, while Mo, Sr, Zr, and Ni decreased with increasing depth. The results show pyrite oxidation at depth and subsequent leaching of the oxidation products. Mn, Zn, Cu, Pb, Ag, and Cd are the most important contaminants of concern at this site. 相似文献
59.
Abstract A theoretical analysis for a fibre-optic ring resonator is given by assuming a polarization modulation in the loop fibre. If the change in polarization angle θ in the loop is large, the output intensity has two resonance dips separated in phase by an angle equal to 2θ, when the loop phase is scanned from 0 to 2π. When θ is small, the resonator output produces only one resonance dip and the amplitude of this resonance dip is a measure of θ. By placing a polarizer at the resonator output, a resonance peak in the intensity is produced with an amplitude that increases with increasing θ. Such a system has potential applications, for example, in Faraday current sensing, with an increased sensitivity. The effects of birefringence in the loop and the angle of polarization of the input light are also analysed. 相似文献
60.
Mahmood M. Shokrieh Masood Esmkhani Faramarz Vahedi Hamid R. Shahverdi 《Iranian Polymer Journal》2013,22(10):721-727
In the present research, the reinforcement effect of vapor grown carbon nanofiber (VGCNF) was studied in relation to the mechanical properties and electrical conduction behavior of fabricated nanocomposites. Different weight fractions of nanofillers into epoxy resin, from 0.05 to 1 wt% and up to 2 wt% for mechanical and electrical properties were investigated. It was found that the optimum improvement in mechanical properties of nanocomposite is obtained at 0.25 wt% of carbon nanofibers. At this filler content, 23 % enhancement in tensile strength and 10 % in flexural strength have been observed. The degree of the VGCNF dispersion has been monitored by means of viscosity variation of the suspension during the sonication process to obtain the optimum sonication time. Finally, the quality of the dispersion for post-cured nanocomposites is characterized by fractured surfaces using the scanning electron microscopy. Agglomerates had a direct effect on the reduction of tensile and flexural strength of nanocomposites. The electrical conductivity was obtained by means of surface measuring method. The optimum amount of filler for the generation of a fine electrical conductivity was found to be around 0.5 wt% of VGCNF. After the threshold point, the electrical conductivity of nanocomposites was slightly raised in spite of adding more filler contents. 相似文献