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61.
Sanaz?Bazaz BehbahaniView authors OrcID profile Xiaobo?TanEmail author 《Journal of Nonlinear Science》2017,27(4):1155-1181
Pectoral fins play a vital role in the maneuvering and locomotion of fish, and they have become an important actuation mechanism for robotic fish. In this paper, we explore the effect of flexibility of robotic fish pectoral fins on the robot locomotion performance and mechanical efficiency. A dynamic model for the robotic fish is presented, where the flexible fin is modeled as multiple rigid elements connected via torsional springs and dampers. Blade element theory is used to capture the hydrodynamic force on the fin. The model is validated with experimental results obtained on a robotic fish prototype, equipped with 3D-printed fins of different flexibility. The model is then used to analyze the impacts of fin flexibility and power/recovery stroke speed ratio on the robot swimming speed and mechanical efficiency. It is found that, in general, flexible fins demonstrate advantages over rigid fins in speed and efficiency at relatively low fin-beat frequencies, while rigid fins outperform flexible fins at higher frequencies. For a given fin flexibility, the optimal frequency for speed performance differs from the optimal frequency for mechanical efficiency. In addition, for any given fin, there is an optimal power/recovery stroke speed ratio, typically in the range of 2–3, that maximizes the speed performance. Overall, the presented model offers a promising tool for fin flexibility and gait design, to achieve speed and efficiency objectives for robotic fish actuated with pectoral fins. 相似文献
62.
Rasouli S Hosseinkhani S Yaghmaei P Ebrahim-Habibi A 《Applied biochemistry and biotechnology》2011,165(2):572-582
In this study, we used sugars as stabilizing additives to improve the thermostability and to inhibit aggregation of firefly
luciferase. The combination of sucrose and trehalose has a strong stabilizing effect on firefly luciferase activity and prevents
its thermoinactivation. These additives can also increase optimum temperature. It has been shown that the presence of both
sucrose and trehalose can inhibit thermal aggregation of firefly luciferase and decrease bioluminescence decay rate. In order
to understand the molecular mechanism of thermostabilization, we investigated the effects of sucrose and trehalose combination
on the secondary structure of luciferase by Fourier transform infrared spectroscopy. Minor changes in content of secondary
structure of firefly luciferase are observed upon treatment with additives. 相似文献
63.
Najmadin Azizi Elahm Gholibeglo Sanaz Dehghan Nayeri 《Monatshefte für Chemie / Chemical Monthly》2012,37(8):1171-1174
Abstract
Multicomponent reactions with ultrasonic activation have been used as a simple, rapid, atom economic, and green method for the synthesis of dithiocarbamate derivatives in water. The one-pot, three-component condensation of primary and secondary amines with carbon disulfide and unsaturated carbonyl compounds or alkyl halides under ultrasonic irradiation was developed as a green and fast protocol for the rapid high-yielding preparation of dithiocarbamates in water. 相似文献64.
An efficient approach for the synthesis of novel 1,3-indandionylamidinium betaines via four-component reaction of 1,3-indandione, aldehydes, amines, and isocyanides, without assistance of any catalyst and under mild reaction conditions has been reported. The structures of these compounds were confirmed by IR, mass spectroscopic, 1H NMR, 13C NMR, and single-crystal X-ray diffraction studies. 相似文献
65.
Mojtaba Lashkari Nourallah Hazeri Malek Taher Maghsoodlou Sayyed Mostafa Habibi Khorassani Niloufar Akbarzadeh Torbati Asghar Hosseinian Santiago García‐Granda Laura Torre‐Fernndez 《Heteroatom Chemistry》2013,24(1):58-65
A three‐component synthesis of α‐aminophosphonate is described from a reaction between aldehydes, 2‐aminobenzothiazole, and triethyl phosphite in the presence of InCl3 as a catalyst under solvent‐free conditions for the generation of the particular α‐aminophosphonates. These products have two potentially biologically active parts, aminophosphonate and benzothiazole. This method offers advantages such as short reaction times, good yields, solvent‐free conditions, and easy workup with the green aspects by avoiding toxic catalysts and solvents. The crystal structure of 4b has been determined by X‐ray crystallography. This compound crystallizes in the monoclinic space group C2/c with cell parameters a = 21.9285(5) Å, b = 10.3221(2) Å, c = 18.5979(5) Å, β = 108.759(3)°, V = 3985.99(18) Å3, Dcalc = 1.301 mg m−3, and Z = 8. The final R value is 0.0501 for 3741 reflections. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 24:58–65, 2013; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21063 相似文献
66.
We compute fractal dimension and permutation entropy for healthy and people who have experienced heart failure. Our result shows that permutation entropy is a suitable approach as well as detrend fluctuation analysis (DFA). The result of DFA shows that the fractal dimensions for healthy and heart failure are different as well as the permutation entropy result. The fluctuation value for permutation entropy for an individual who has experienced heart failure is bigger than for a healthy person. There is some specific change in the interbeat signal of a person who has experienced heart failure, but there is not previous trend for a healthy person. 相似文献
67.
B. Amrani F. El Haj Hassan H. Akbarzadeh 《Journal of Physics and Chemistry of Solids》2009,70(7):1055-1061
We have performed first-principles calculations using full potential linearized augmented plane wave (FP-LAPW) method within density functional theory (DFT) to investigate the fundamental properties of CuxAg1−xI alloys. We used both GGA96 [J.P. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett. 77 (1996) 3865.] and EVGGA [E. Engel, S.H. Vosko, Phys. Rev. B. 47 (1993) 13164.] generalized gradient approximations of the exchange-correlation energy that are based on the optimization of total energy and corresponding potential. Quantities such as lattice constants, bulk modulus, band gap, density of occupied states and effective mass were calculated as a function of copper molar fraction x. These parameters were found to depend non-linearly on alloy composition x, except the lattice parameter, which follows Vegard's law. The microscopic origins of the gap bowing were explained using the approach of Zunger and co-workers; we have concluded that the band-gap energy bowing was mainly caused by the chemical charge-transfer effect and the volume deformation , while the structural relaxation contribute to the gap bowing parameter at smaller magnitude. The calculated phase diagram shows a broad miscibility gap for this alloy with a high critical temperature. 相似文献
68.
Issa Yavari Mohammad J. Bayat Sanaz Souri Mehdi Sirouspour 《Helvetica chimica acta》2009,92(9):1903-1907
A one‐pot synthesis of 2‐(4‐oxo‐1,3‐thiazinan‐5‐yl)acetic acids is described via a three‐component reaction between primary alkylamines and ithaconic anhydride and phenyl isothiocyanate or benzoyl isothiocyanate. 相似文献
69.
The 1:1 zwitterionic intermediates obtained from the reaction between isoquinoline, quinoline, pyridine, or N-methylimidazole with activated acetylenes are trapped by ethyl pyruvate to produce highly functionalized fused [1,3]oxazines
in good yields. 相似文献
70.
Mina Abbasipour Ramin Khajavi Ali Akbar Yousefi Mohammad Esmail Yazdanshenas Farhad Razaghian Abdolhamid Akbarzadeh 《先进技术聚合物》2019,30(2):279-291
In this study, it was aimed to increase the piezoelectric and pyroelectric properties of electrospun polyvinylidene fluoride (PVDF) nanofibers simultaneously by using specific nanofillers. Graphene oxide (GO), graphene, and halloysite nanotubes with different concentrations (0, 0.05, 0.4, and 1.6% wt/wt) were combined with PVDF solution and were fabricated in the form of nanofibers through electrospinning. Pyroelectric properties of samples were measured by submerging sealed samples in hot water (360°K) and ice (270°K). The piezoelectric properties of the samples were evaluated through bending tests. The microstructural, mechanical, and thermal properties of the electrospun PVDF nanocomposite were investigated using scanning electron microscope, Instron instrument, and thermogravimetric analysis, respectively. To further support the experimental observations for generating electric voltage in the bended nanogenerator, the PVDF nanogenerator (PNG) was also modeled by a finite element analysis based on the theory of linear piezoelectricity using COMSOL Multiphysics simulation software. Experimental results showed that adding nanofillers could improve the piezoelectric and pyroelectric properties of all samples, associated with the increment of β‐phase in the nanofibers. It was concluded that adding nanofillers could increase pyroelectricity about 50% more than piezoelectricity in pristine PVDF nanofiber web. The PNG containing 1.6 wt% GO showed the highest efficiency in terms of piezoelectricity and pyroelectricity. In addition, the results showed that the ratio of piezoelectric to pyroelectric coefficients was constant (~1.5) and it was independent of the nanofiller type and content. The effect of external force and vibration frequency on the output voltage was also investigated. Increasing the compressive force and vibration frequency caused a greater output voltage. Finally, the fabricated nanogenerator was integrated on insole and elbow to investigate its energy harvesting capabilities from body movement. 相似文献