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81.
82.
Saba Hemmati Alireza Sedrpoushan Nazanin Soudalizadeh Kaveh Khosravi Malak Hekmati 《应用有机金属化学》2019,33(10)
A green palladium (Pd)‐based catalyst supported on Rosa canina fruit extract‐modified graphene oxide [Pd nanoparticles (NPs)/reduced graphene oxide (RGO)‐Rosa canina] hybrid materials has been used as a recoverable and heterogeneous nanocatalyst for cyanating aryl halides using K4[Fe (CN)6] as the resource of cyanide. The nitriles were achieved in good to high yield, and the catalyst can be recovered and reused for up to seven cycles with no remarkable decrease in its catalytic activity. 相似文献
83.
M. R. Ayatollahi M. Dehghany Z. Kaveh 《Archive of Applied Mechanics (Ingenieur Archiv)》2013,83(3):345-356
Four-point bend (FPB) specimen is an important test sample in mixed mode fracture study of notched components made from brittle materials like rocks, brittle polymers, ceramics, etc. On the other hand, the notch stress intensity factors (NSIFs) are vital parameters in brittle fracture assessment of V-notched structures. Therefore, computation of NSIFs in FPB specimens is of practical interest to engineers and researchers. Since the available methods for calculating the NSIFs are often cumbersome and need complicated calculations, it is preferred to show them as a set of dimensionless parameters for the FPB specimen. In this research, the finite element method coupled with a recently developed algorithm called FEOD is employed to calculate the NSIFs of a FPB specimen for several V-shape notches and for different combinations of mode I and mode II. The obtained NSIFs are then converted to dimensionless parameters called notch shape factors and are illustrated in a number of figures. It is shown that depending on the notch depth and the location of loading points, full mode mixity from pure mode I to pure mode II can be provided in the FPB specimen. The numerical results obtained in this research are verified by using very limited results reported earlier in literature. 相似文献
84.
Kaveh Merat Hassan Salarieh Aria Alasty 《Journal of Computational and Applied Mathematics》2009,233(2):531-544
In this paper the control of discrete chaotic systems by designing linear feedback controllers is presented. The linear feedback control problem for nonlinear systems has been formulated under the viewpoint of dynamic programming. For suppressing chaos with minimum control effort, the system is stabilized on its first order unstable fixed point (UFP). The presented method also could be employed to make any desired nth order fixed point of the system, stable. Two different methods for higher order UFPs stabilization are suggested. Afterwards, these methods are applied to two well-known chaotic discrete systems: the Logistic and the Henon Maps. For each of them, the first and second UFPs in their chaotic regions are stabilized and simulation results are provided for the demonstration of performance. 相似文献
85.
Classification of experimental datasets such as target and clutter in sonar applications is a complex and challenging problem. One of the most useful instrument to classify sonar datasets is Multi-Layer Perceptron Neural Network (MLP NN). In this paper, due to the optimally updating the weights and biases vector of the MLP NN, Biogeography-Based Optimization (BBO) is used to train the network. BBO has a fair ability to solve high-dimensional real-world problems (such as sonar dataset classification) by maintaining a suitable balance between exploration and exploitation phases. The performance of BBO is sensitive to the migration model, especially for high-dimensional problems. To improve the exploitation ability of BBO and to record the better results for classifying sonar dataset, we propose novel migration models such as exponential-logarithmic, and some improved migration models having different emigration and immigration mathematical functions. To validate the performance of the proposed classifiers, this network will classify three datasets with various sizes and complexities. The simulation results indicate that our newly proposed classifiers perform better than the other benchmark algorithms in addition to original BBO in terms of avoiding gets stuck in local minima, classification accuracy, and convergence speed. 相似文献
86.
Hassan Salarieh Hoda Sadeghian Kaveh Merat 《Nonlinear Analysis: Real World Applications》2009,10(5):2864-2872
In this paper the problem of chaos control in single mode lateral oscillations of spinning disks is studied. At first, using the harmonic balance method, one of the periodic orbits of system is evaluated. Then proposing a nonlinear feedback strategy a control law is presented for chaos elimination by tracking the mentioned periodic solution. It is shown that although the system is not input-state feedback linearizable, by defining an output signal and using the input–output linearization method, the objective of complete periodic orbit tracking is achieved. The sufficient condition for this purpose is presented, and the performance of proposed method is examined by numerical simulation. 相似文献
87.
Oscillating chemical reactions are complex systems, involving a large number of chemical species. In an oscillating chemical
reaction, some species, usually a reaction intermediate, exhibit fluctuation in its concentration. In this report, oscillating
chemiluminescence produced by the addition of thiosemicarbazide (TSC) to the oscillating system H2O2–KSCN–CuSO4–NaOH was investigated using luminometry method. The effects of complexing agents, triethylenetetramine (TETA) and D-penicillamine,
on the behavior of the oscillating system were investigated. Moreover, the influence of non-aqueous solvents, dimethyl sulfoxide
(DMSO), nitromethane and acetonitrile, was studied. In the presence of solvents with high protophility, the chemiluminescence
(CL) intensity was increased (sevenfold), the light emitting and oscillating time was enhanced by threefold. In addition,
the effect of presence of non-ionic, cationic, and anionic surfactants was investigated. Non-ionic surfactant increased the
intensity of the oscillating CL reaction by 4.5-fold. 相似文献
88.
The delocalization of electron states in one-dimensional metals, such as TTF-TCNQ, accounts for the observed itinerant motion of the electrons at temperatures above about 50 K. This delocalization is related to the extended nature of the molecules in organic metals, which causes the amplitude for forward scattering by the phonons to exceed the amplitude for backward scattering by an order of magnitude. The large forward scattering, which delocalizes the electrons, does not contribute to the resistivity in the delocalized state. 相似文献
89.
H. Maleki-Ghaleh M.S. Shakeri Z. Dargahi M. Kavanlouei H. Kaveh Garabagh E. Moradpur-Tari A. Yourdkhani A. Fallah A. Zarrabi B. Koc M.H. Siadati 《Materials Today Chemistry》2022
The optical and electronic properties of molybdenum (Mo) doped rutile TiO2 prepared by the mechanochemical method were studied both experimentally and using density functional theory (DFT). The synthesized nanoparticles were characterized by XRD, TEM, EDS-MAP, and XPS. The XRD results showed the successful incorporation of Mo in the rutile crystal lattice. High-resolution TEM images illustrated a decreasing trend in the (110) d-spacing for samples doped up to 3 at%. The shift toward higher binding energies in the XPS spectra was due to the higher oxidization tendencies of Mo5+ and Mo6+ substituted in Ti4+ sites. The optical behavior of samples was examined by UV–Vis and photoluminescence spectroscopy. The bandgap energy value of rutile was reduced from 3.0 eV to 2.4 eV by 2 at% Mo doping. The DFT calculations showed a reduction of bandgap energy value of rutile to 2.35 eV with 2 at% Mo, which is in harmony with the experimental results. The creation of energy states below the conduction band because of Mo doping was identified as the reason for reducing the bandgap energy and photoluminescence emission of rutile. 相似文献
90.
Kaveh Parvanak Boroujeni 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2085-2091
A simple, chemoselective, and efficient method has been developed for direct conversion of arenes to symmetrical diaryl sulfoxides using thionyl chloride in the presence of a catalytic amount of cross-linked polystyrene-supported aluminium chloride (Ps-AlCl3) and silica gel–supported aluminium chloride (SiO2-AlCl3). These solid acid catalysts are stable and can be easily recovered and reused without appreciable change in their efficiency. 相似文献