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41.
Alireza Khorsandi Saeed Ghavami Sabouri Somaieh Fathi Marzieh Asadnia-Jahromi 《Optics & Laser Technology》2011,43(5):956-959
We have reported a modified V-shaped external cavity, which is constructed around a commercial diode laser operating at a center wavelength of λ=785 nm by adding a new coated glass plate with about 50% reflectivity to the cavity. This allows simultaneous dual-wavelengths operation in the vicinity of Δνmin=0.18 THz to Δνmax=0.22 THz, which can be used as laser source for terahertz generation either for semiconductor devices or nonlinear schemes. 相似文献
42.
Toyohisa Fujita Hyun-Seo ParkKenji Ono Seiji MatsuoKatsunori Okaya Gjergj Dodbiba 《Journal of magnetism and magnetic materials》2011,323(10):1207-1210
In this work, a temperature sensitive functional fluid was synthesized, and then its movement under the influence of magnetic field was investigated. Silica coated FeNbVB particles, prepared by chemical synthesis, were dispersed into liquid gallium, because they have a relatively high magnetization and a high temperature dependency. The synthesized functional fluid (solid fraction of 0.3 mass%) showed temperature dependence for magnetization within the testing temperature range between 298 and 353 K. The movement of gallium based fluid under the influence of the magnetic field with a magnetic field gradient was observed at various temperatures. We found that at 318 K, fluid displacement of the synthesized functional fluid is better when compared with the fluid displacement at 348 K. 相似文献
43.
44.
We study the dynamic stability and instability of pinned fundamental ±1 vortex solutions to the Ginzburg–Landau equations
with external potential in ℝ2. For sufficiently small external potentials, there exists a perturbed vortex solution centered near each non-degenerate critical
point of the potential. With respect to both dissipative and Hamiltonian dynamics, we show that perturbed vortex solutions
which are concentrated near local maxima (resp. minima) are orbitally stable (resp. unstable). In the dissipative case, the
stability is in the stronger “asymptotic” sense.
The research of S. Gustafson partially supported by a grant from NSERC.
The research of F. Ting on this paper was supported by NSERC under grant N298724. 相似文献
45.
Alison Castro Superfine Reality S. Canty Anne Marie Marshall 《The Journal of Mathematical Behavior》2009,28(4):217-236
The study described herein represents an initial, exploratory attempt to understand what it means to translate between external representation systems. Researchers have traditionally considered translation as an all-or-none activity. We hypothesize that translation is comprised of both knowledge and skill components, and accordingly construe translation as an activity that our framework allows us to define as partial or complete. We examined the effects of part-whole knowledge in change unknown subtraction situations and the structure of three different external representations on first grade students’ ability to translate in a partitioning task. Based on three interviews conducted with each student, results from our mixed methods analysis showed that translation skill was affected by what students knew about subtraction and the structure of the ER. Further, whereas high knowledge students demonstrated greater difficulty with translating to the ERs, low knowledge students had difficulty translating from the problem statement as well as translating to the ERs. 相似文献
46.
In this paper a general three-dimensional simulation of turbulent fluid flow is presented to predict velocity and pressure fields for a centrifugal pump. A commercial CFD code was used to solve the governing equations of the flow field. In order to study the most suitable turbulence model, three known turbulence models of standard k–ε, RNG and RSM were applied. The complex flow configuration required us to use around 5,800,000 cells, and 12 computational nodes (processors) for parallel computing. Simulation results in the form of characteristic curves were compared with available experimental data, and an acceptable agreement was obtained. Additionally, effect of number of blades on the efficiency of pump was studied. The number of blades was changed from 5 to 7. The results show that the impeller with 7 blades has the highest head coefficient. Finally, it was observed also that the position of blades with respect to the tongue of volute has great effect on the start of the separation. Thus, to analyze the effect of blade number on the characteristics of the pump, the position of blade and tongue should be similar to each other. Investigations of this kind may help to reduce the required experimental work for the development and design of such devices. 相似文献
47.
48.
Trong Phu Do Pascal Ziegler 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2013,19(4):359-388
Gear drives are key components for all kinds of machines as well as of industrial equipment. Therein, beveloid gears and cycloid gears are increasingly used in industry. Gaining a more comprehensive understanding of those types of gears is essential. However, the measurement of the dynamic response of these gears is not an option due to the high cost of the required experiments. Along with the development of computer technology, several numerical tools and methods to study gears with standard and non-standard flank profiles have been introduced. Various works related to standard gears or beveloid and cycloid gears have been published. In this study, a contemporary review about the modelling and contact simulation of beveloid and cycloid gear drives will be given. Some studies will also be introduced to present an efficient approach to simulate contact forces and contact characteristics of gear wheels with standard and non-standard tooth profiles considering deformations too. 相似文献
49.
Electrospun membranes are widely utilized to enhance the water vapor permeability and drug delivery performance of transdermal drug delivery patches. Due to the lack of adhesion property,however,most of them cannot closely contact with skin,which impedes the delivery of drugs to the skin,thus affecting the transdermal administration. C5 resin is used to endow poly(styrene isoprene styrene)(SIS)electrospun membranes with pressure-sensitive adhesion property. Investigation is performed on how to control the structure,adhesion properties and drug delivery performance of SIS/C5 electrospun membranes loaded with synthetic capsaicin via compositions,drugs and electrospinning conditions. The results demonstrate that the electrospun membrane with a SIS/C5 ratio of 2∶1 has excellent water vapor permeability(7. 17×10-3 g/(h·cm2)and adhesion properties(180(°)peel strength is 0. 2 kN/m,tack force is 0. 64 N/cm2 ,holding power is greater than 7 days). The synthetic capsaicin has good compatibility with the SIS/C5 electrospun membranes,in which no drug crystallizes and the drug loading is beneficial to improve the water vapor permeability. As the drug loading is 8%,the tack force is 0. 6~0. 8 N/cm2 ,the 180(°)peel strength is 0. 2~0. 3 kN/m,the holding power is greater than 7 days,and no residue is left during peeling tests. In vitro drug release indicates that the drug has a behavior of sustained release with a 24-hour cumulative release rate of greater than 50% for all SIS/ C5 electrospun membranes,meeting the requirements of transdermal drug delivery patches. © 2022, Science Press (China). All rights reserved. 相似文献
50.
A series of(Si_O2/MgO/ID/MgCl_2)·TiClx Ziegler-Natta catalysts for propylene polymerization has been prepared with a new method. These catalysts were synthesized using soluble Mg-compounds as the Mg-source and the preparation progress was relatively simple. The catalyst could copy the spherical shape of the carrier very well. The propylene polymerization results showed that the catalyst revealed the best activity with 9,9-di(methoxymethyl)fluorene(BMMF) as internal donor at 50 °C with the optimal molar ratio Al/Ti = 5, which was much lower than what the industrial polypropylene catalyst used(at least molar ratio Al/Ti = 100), resulting in great cost saving. Additionally, the polymerization kinetics of the catalyst exhibited very stable property after achieving a relatively high value. These catalysts possessed rather high activity and good hydrogen response. The isotactic index(Ⅱ.) value of the PP products could be higher than 98% in the presence of both internal and external electron donors. Moreover, temperature rising elution fractionation method was used to understand the influence of donors and H2 on the properties of the PP products. 相似文献