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81.
Siavash Sattar Rahul Jujjavarapu Sergei G. Kravchenko Oleksandr G. Kravchenko 《Journal of the American Ceramic Society》2020,103(11):6543-6553
In this study, a novel computational micromechanical framework is proposed to predict the effective mechanical properties of the ice-templated ceramics under off-axis compressive loading. The mechanical behavior is simulated by a computational micromechanical model and validated against experimental results. Smeared cracking approach was used to describe failure in ice-templated alumina. The representative volume element (RVE) was developed based on the honeycomb analogy of lamellar walls considering the morphology of the material. The periodic boundary conditions were applied in RVE to simulate bulk behavior of the material. The compression testing was conducted on the ice-templated alumina samples to obtain the effective compressive moduli and strength with different loading angles. Digital image correlation method was used to measure strain field during the experiment and quantify the effective misalignment angle corresponding to porous material. The effective stiffness and strength obtained from RVE analysis compared well with experimental results. The proposed micro-mechanical RVE model allows for determining the properties of the ice-templated porous ceramic for various off-axis angles. 相似文献
82.
Maryam Ranjbar Mostafa Yousefi 《Journal of Inorganic and Organometallic Polymers and Materials》2014,24(3):652-655
A new nano-sized La(III) supramolecular compound, [pyda.H]2[La2(pydc)4(H2O)4]·2H2O (1), where [pyda.H]+ = 2,6-diaminopyridinium, and [pydc]2? = 2,6-pyridinedicarboxylate, was synthesized by the sonochemical method and characterized by field emission scanning electron microscope (FESEM), X-ray powder diffraction (XRD) and elemental analyses. Lanthanum oxide nanoparticles were prepared by direct thermal decomposition of 1 nanostructures in a programmable furnace up to 800 °C in ambient atmosphere. The structural characterization was performed by powder XRD; and, morphological observations by FESEM revealed that the quasi-spherical La2O3 nanoparticles obtained are well crystallized and uniform in both morphology and particle size. The study demonstrates that supramolecular compounds may be suitable precursors for the simple one-pot preparation of nanoscale metal oxide materials with different morphologies. 相似文献
83.
Powder Metallurgy and Metal Ceramics - An extensive scanning electron microscopy and image analysis is carried out on Alumina and Zirconia Dispersed Alumina (ZDA) ceramic composites containing... 相似文献
84.
Aziz A. Fallah Fariba Zeynali S. Siavash Saei-Dehkordi Mohammad Rahnama Tina Jafari 《Journal für Verbraucherschutz und Lebensmittelsicherheit》2011,6(3):367-374
This study aimed to determine the concentrations of aluminium, cadmium, lead and nickel in edible muscle of three commercially valuable fish species (Rutilus frisii kutum, Liza aurata and Cyprinus carpio) from four fishing sites of Iranian coastal waters of the Caspian Sea during winter and summer. The samples were analyzed using graphite furnace atomic absorption spectrometry (GFAAS) after wet-ashing digestion. The results were expressed as ??g/g of wet weight. The resulted range of metals in fish species was between 0.89?C2.46???g/g for aluminium, 0.03?C0.17???g/g for cadmium, 0.21?C0.38???g/g for lead and 0.12?C0.52???g/g for nickel. Seasonal variation influenced concentration of the metals in fish samples of some fishing sites. The highest concentrations found were 4.63???g/g for aluminium in winter and 0.82???g/g for lead in summer in Cyprinus carpio; while cadmium (0.49???g/g) and nickel (1.14???g/g) were the highest in Rutilus frisii kutum in winter. This demonstrates that estimated daily and weekly intakes of aluminium, lead and nickel and estimated monthly intake of cadmium via consumption of fish flesh are below the established PTDI, PTWI and PTMI values. 相似文献
85.
Siavash Riahi Kowsar Bagherzadeh Nazila Davarkhah Mohammad Reza Ganjali Parviz Norouzi 《Materials science & engineering. C, Materials for biological applications》2011,31(5):992-996
A numerical simple, accurate and precise method based on spectrophotometric data coupled with multivariate calibration methods, PLS and MLR, combined with GA was developed for the simultaneous determination of two benzodiazepines, Clobazam and Flurazepam. A data set of absorption spectra obtained from a calibration set of mixtures containing the compounds was used to build GA-PLS and GA-MLR models. The models were tested using a dataset constructed from the compound synthetic solutions. The better model was also applied to plasma samples. The proposed method requires no preliminary separation steps and can be used for these drugs analysis in quality control laboratories. 相似文献
86.
87.
Zohreh Rashidi Ranjbar Ali Morsali 《Journal of Inorganic and Organometallic Polymers and Materials》2011,21(3):421-430
A new zinc(II) coordination polymer, {[Zn(bpcdp)2(DMF)4](ClO4)2·(H2O)2}n (1) bpcdp = 2,6-bis(4-pyridinecarboxamide)pyridine has been synthesized and characterized by IR, 1HNMR and 13CNMR spectroscopy. The single crystal X-ray data of compound 1 shows the zinc(II) atom has been considered as octahedral with ZnN2O4 coordination sphere. Two nitrogen atoms of bpcdp ligand and four oxygen atoms of DMF molecules have occupied coordination
sphere around zinc(II) atoms. The prepared zinc(II) coordination polymer grows in three-dimensional network by hydrogen bonding
and π–π stacking interaction. The nanostructure of compound 1 were obtained by sonochemical process and studied by scanning electron microscopy (SEM), X-ray powder diffraction (XRD),
IR and NMR spectroscopy. Thermal stabilities of single crystalline and nano-size samples of compound 1 were studied by thermal gravimetric (TG) and differential thermal analyses (DTA). The ZnO nanoparticles were obtained by
direct calcination of compound 1 at 400 °C and by thermolysis in oleic acid at 200 °C. The obtained zinc(II) oxide nanoparticles were characterized by X-ray
diffraction (XRD) and scanning electron microscopy (SEM). 相似文献
88.
Seyed Ali Asghar Akbari Mousavi Shahab Ranjbar Bahador 《JOM Journal of the Minerals, Metals and Materials Society》2011,63(2):69-76
The effects of performing three twist extrusion passes on high purity aluminum samples were studied in this paper in regard
to numerical analysis and experimental studies. The finite element analysis of the von-Mises stress and the equivalent plastic
strain in the outer longitudinal and transverse cross-sections, which are parallel and normal to the billet axis respectively,
was carried out. The simulation results showed that the end of the workpiece underwent more equivalent plastic strains in
contrast to the head of the sample. Moreover, the corner regions experienced more strains than the center zone did. However,
the heterogeneity in strain distribution in both longitudinal and transverse cross-sections decreased by performing the sequential
twist extrusion passes. The experimental outcomes such as microstructure evolutions, microhardness and tensile tests validated
the simulation results. 相似文献
89.
Siavash Ghavami Olaf Wolkenhauer Farshad Lahouti Mukhtar Ullah Michael Linnebacher 《IET systems biology》2014,8(5):230
Knowing the expected temporal evolution of the proportion of different cell types in sample tissues gives an indication about the progression of the disease and its possible response to drugs. Such systems have been modelled using Markov processes. We here consider an experimentally realistic scenario in which transition probabilities are estimated from noisy cell population size measurements. Using aggregated data of FACS measurements, we develop MMSE and ML estimators and formulate two problems to find the minimum number of required samples and measurements to guarantee the accuracy of predicted population sizes. Our numerical results show that the convergence mechanism of transition probabilities and steady states differ widely from the real values if one uses the standard deterministic approach for noisy measurements. This provides support for our argument that for the analysis of FACS data one should consider the observed state as a random variable. The second problem we address is about the consequences of estimating the probability of a cell being in a particular state from measurements of small population of cells. We show how the uncertainty arising from small sample sizes can be captured by a distribution for the state probability.Inspec keywords: cancer, tumours, cellular biophysics, biomedical measurement, Gaussian distribution, maximum likelihood estimation, mean square error methods, hidden Markov models, fluorescence, random processes, convergence of numerical methodsOther keywords: cancer cell population dynamics, malignant tumours, tissue samples, normal tissue cells, disease, drugs, Markov process, cell population size measurement, hidden Markov model, noisy measurement, state transition probability, fluorescence‐activated cell sorting measurement, minimum mean square error estimator, maximum likelihood estimator, transition probability matrix, noise distributions, Gaussian distributions, MMSE, convergence mechanism, standard deterministic approach, stochastic phenomena, random variable 相似文献
90.
Babak Ranjbar Abolfazl Ranjbar Noiey Behrooz Rezaie 《International Journal of Adaptive Control and Signal Processing》2021,35(10):2094-2107
In this article, a decentralized adaptive integral terminal sliding mode control is presented for a class of nonlinear connected systems. It is assumed that the system is also confronted by unknown disturbances, while the interconnections between subsystems are assumed unknown. An integral terminal sliding surface for each subsystem is locally considered to guarantee the stability of the closed-loop system, and to increase the convergence speed during a tracking task. The unknown interconnections between subsystems are estimated using adaptive rules. An appropriate Lyapunov candidate is chosen to perform global stability analysis. In this regard, design parameters are chosen such that the closed-loop stability is ensured. Performance of the proposed method for a mechanical connected system, including two chaotic subsystems, is shown through simulations. 相似文献