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151.
A. F. A. Algarray H. Jun I.-E. M. Mahdi 《Journal of Applied Mechanics and Technical Physics》2017,58(6):1108-1114
The effects of the end conditions of cross-ply laminated composite beams on their dimensionless natural frequencies of free vibration is investigated. The problem is analyzed and solved by using the energy approach, which is formulated by a finite element model. Various end conditions of beams are used. Each beam has either movable ends or immovable ends. Numerical results are verified by comparisons with other relevant works. It is found that more constrained beams have higher values of natural frequencies of transverse vibration. The values of the natural frequencies of longitudinal modes are found to be the same for all beams with movable ends because they are generated by longitudinal movements only. 相似文献
152.
Drag amplification of long flexible riser models undergoing multi-mode VIV in uniform currents 总被引:2,自引:0,他引:2
Measurement data of long flexible riser models are used to study the drag amplification due to multi-mode vortex induced vibration (VIV). The riser model was towed in a towing tank, and vibration along its length was measured indirectly at a set of discrete points using accelerometers, along with the total drag and lift forces on the model. These data were used to fit expressions for the drag amplification taking into account the spatial variation of the vibration amplitude along the riser length. The results were compared with the existing empirical expression used in the VIV analysis tool SHEAR7 as well as other test data. It was found that the expression in SHEAR7 agrees well with the test data. However, for larger vibration amplitudes, it appears to under-predict the drag amplification. 相似文献
153.
Steady and pulsatile flow and heat transfer in a channel lined with two porous layers subject to constant wall heat flux under
local thermal non-equilibrium (LTNE) condition is numerically investigated. To do this, a physical boundary condition in the
interface of porous media and clear region of the channel is derived. The objective of this work is, first, to assess the
effects of local solid-to-fluid heat transfer (a criterion indicating on departure from local thermal equilibrium (LTE) condition),
solid-to-fluid thermal conductivity ratio and porous layer thickness on convective heat transfer in steady condition inside
a channel partially filled with porous media; second, to examine the impact of pulsatile flow on heat transfer in the same
channel. The effects of LTNE condition and thermal conductivity ratio in pulsatile flow are also briefly discussed. It is
observed that Nusselt number inside the channel increases when the problem is tending to LTE condition. Therefore, careless
consideration of LTE may lead to overestimation of heat transfer. Solid-to-fluid thermal conductivity ratio is also shown
to enhance heat transfer in constant porous media thickness. It is also revealed that an increase in the amplitude of pulsation
may result in enhancement of Nusselt number, while Nusselt number has a minimum in a certain frequency for each value of amplitude. 相似文献
154.
155.
Sayyid Mahdi Rafigh Amir Heydarinasab 《International Journal of Polymer Analysis and Characterization》2017,22(6):497-508
In this study, hydroxyethyl curdlans (HeCDs) with different molecular weights were successfully fabricated. The structure and properties of the synthesized HeCDs were measured by FTIR, 13C nuclear magnetic resonance (NMR), and Raman spectroscopy and compared with curdlan. The degree of crystallinity of HeCDs was measured with X-ray diffractometry (XRD). Differential scanning calorimetry and thermogravimetric analysis were performed to determine thermal properties of HeCs. Solubility of HeCDs was tested in water, common organic solvents, and NaOH solution. Antioxidant activities of HeCs were investigated using various in vitro assay systems. The HeCDs exhibited a dose-dependent free radical scavenging activity as shown by their DPPH radical, ABTS radical and superoxide anion radical inhibition, and ferrous chelating ability and reducing power. The improved water solubility property and antioxidant activity of these curdlan derivatives could have a wide range of applications, particularly its use as an antioxidant in food, food packaging, biomedical, and pharmaceutical industries. 相似文献
156.
Mahdi?Saedshoar?Heris Mohammad?JavidiEmail author 《Mediterranean Journal of Mathematics》2017,14(3):134
In this paper, we study the fractional backward differential formula (FBDF) for the numerical solution of fractional delay differential equations (FDDEs) of the following form: \(\lambda _n {}_0^C D_t^{\alpha _n } y(t - \tau ) + \lambda _{n - 1} {}_0^C D_t^{\alpha _{n - 1} } y(t - \tau ) + \cdots + \lambda _1 {}_0^C D_t^{\alpha _1 } y(t - \tau ) + \lambda _{n + 1} y(t) = f(t), t \in [0,T]\), where \( \lambda _i \in \) \(\mathbb {R}\,(i = 1,\ldots ,n + 1)\,,\,\lambda _{n + 1} \ne 0,\,\, 0 \leqslant \alpha _1< \alpha _2< \cdots< \alpha _n < 1,\,\,T > 0,\) in Caputo sense. We find the Green’s functions for this equation corresponding to periodic/anti-periodic conditions in term of the Mittag-Leffler type. Our investigation is focused on stability properties of the numerical methods and we determine stability regions for the FDDEs. Finally, some numerical examples are given to show the effectiveness of the numerical method and the results are in excellent agreement with the theoretical analysis 相似文献
157.
Hofmeister effect challenge 总被引:1,自引:0,他引:1
158.
Many properties of silicon carbide (SiC) nanotubes, such as their high mechanical strength and resistance to corrosive environments, are superior to those of their carboneous counterparts, namely, carbon nanotubes (CNTs) and, therefore, SiC nanotubes can be a viable alternative to CNTs in a variety of applications. We employ molecular dynamics simulations to examine flow of water in SiC nanotubes and to study the differences and similarities with the same phenomenon in the CNTs. The simulations indicate that SiC nanotubes always provide larger flow enhancements than those reported for the CNTs. Moreover, a given flow enhancement in SiC nanotubes requires an applied pressure gradient that is at least an order of magnitude smaller than the corresponding value in a CNT of the same size. 相似文献
159.
160.
Ekechukwu Gerald K. Khishvand Mahdi Kuang Wendi Piri Mohammad Masalmeh Shehadeh 《Transport in Porous Media》2021,136(2):369-410
Transport in Porous Media - On the basis of a well-based model (Model I) developed in a previous work (Liu and Valkó in SPE J 2019. https://doi.org/10.2118/197049-PA ), in which a fractional... 相似文献