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排序方式: 共有1224条查询结果,搜索用时 62 毫秒
1.
Khalil Ghanbari Ali Akbar Golneshan Mohsen Yazdani Hesam Moghadasi Navid Malekian 《亚洲传热研究》2021,50(6):5697-5713
Nanofluids have been known as practical materials to ameliorate heat transfer within diverse industrial systems. The current work presents an empirical study on forced convection effects of Al2O3–water nanofluid within an annulus tube. A laminar flow regime has been considered to perform the experiment in high Reynolds number range using several concentrations of nanofluid. Also, the boundary conditions include a constant uniform heat flux applied on the outer shell and an adiabatic condition to the inner tube. Nanofluid particle is visualized with transmission electron microscopy to figure out the nanofluid particles. Additionally, the pressure drop is obtained by measuring the inlet and outlet pressure with respect to the ambient condition. The experimental results showed that adding nanoparticles to the base fluid will increase the heat transfer coefficient (HTC) and average Nusselt number. In addition, by increasing viscosity effects at maximum Reynolds number of 1140 and increasing nanofluid concentration from 1% to 4% (maximum performance at 4%), HTC increases by 18%. 相似文献
2.
Max J. Cotler Erin B. Rousseau Khalil B. Ramadi Joshua Fang Ann M. Graybiel Robert Langer Michael J. Cima 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(37)
Enhanced understanding of neuropathologies has created a need for more advanced tools. Current neural implants result in extensive glial scarring and are not able to highly localize drug delivery due to their size. Smaller implants reduce surgical trauma and improve spatial resolution, but such a reduction requires improvements in device design to enable accurate and chronic implantation in subcortical structures. Flexible needle steering techniques offer improved control over implant placement, but often require complex closed‐loop control for accurate implantation. This study reports the development of steerable microinvasive neural implants (S‐MINIs) constructed from borosilicate capillaries (OD = 60 µm, ID = 20 µm) that do not require closed‐loop guidance or guide tubes. S‐MINIs reduce glial scarring 3.5‐fold compared to prior implants. Bevel steered needles are utilized for open‐loop targeting of deep‐brain structures. This study demonstrates a sinusoidal relationship between implant bevel angle and the trajectory radius of curvature both in vitro and ex vivo. This relationship allows for bevel‐tipped capillaries to be steered to a target with an average error of 0.23 mm ± 0.19 without closed‐loop control. Polished microcapillaries present a new microinvasive tool for chronic, predictable targeting of pathophysiological structures without the need for closed‐loop feedback and complex imaging. 相似文献
3.
The hydraulic‐thermal characteristics of 3D pinned heat sink designs have been numerically compared as the first part of a three‐part investigation. Five different pin geometries (circular, square, triangular, strip, and elliptic pins) and an unpinned heat sink with three types of nanofluids (Al2O3–H2O, SiO2–H2O, and CuO–H2O) are considered for laminar forced convection. The range of Reynolds number is from 100 to 1000, and volume fractions vary between 0% and 5%. The finite volume method is employed to solve the Navier–Stokes and energy equations by employing a SIMPLE algorithm for a computational solution. Three parameters are presented—the Nusselt number, the bottom temperature, and the hydrothermal performance of the heat sink with pressure drop data. The findings indicated that the overall hydrothermal performance of elliptic‐pinned (EP) heat sinks produces the most substantial value of 3.10 for pure water. For different nanofluids, the SiO2–water nanofluids with EPs have the most significant hydrothermal performance. Also, this factor is enhanced with an increase in nanofluid concentration up to nearly 3.34 for 5% of SiO2–water. Consequently, applying the elliptic‐pinned heat sinks is recommended with pure water for considering an increase in the pressure drop, with 5% of SiO2–water nanofluids, regardless of an enlargement of pressure drop for heat‐dissipation applications. 相似文献
4.
Nano-Magnesium ferrite (MgFe2O4) powders have been prepared by a modified combustion synthesis method named impregnated active layer combustion (IALC). The effects of five important parameters such as main fuel to oxidizer ratio (F/O), main fuel type, added fuel type, template type and main fuel (Added F/MF) to the added fuel ratio have been studied using Taguchi design. Xylitol, D-mannitol, ethylene diamine tetra acetic acid (EDTA) and diethylene triamine penta acetic acid (DTPA) were used as fuels. Besides, waste newspaper and Platanus orientalis leaf (POL) were used as new green templates. Samples were characterized by XRD, XRF, SEM, TEM, BET and VSM analyses. Results showed that the average crystallite size of the sample prepared under optimized condition (mixture of Xylitol and DTPA as fuel, POL as template, and Added F/MF ratio of 0.75) was 17.66?nm. The result was confirmed by TEM. The saturated magnetization of the optimum sample was 21?emu/g and the specific surface area was 15.377?m2/g. 相似文献
5.
6.
Hessam Golmohamadi 《国际能源研究杂志》2021,45(1):938-960
This paper proposes a novel structure to optimize the operational strategies of responsive farms for day‐ahead peak shaving. To achieve the aim, the modern irrigation system of farms, including groundwater, surface water, and booster water pumps, are modeled mathematically. To develop the demand response (DR) potentials of the farms, electrical storage systems, and self‐generation facilities, including thermal distributed generations and on‐farm solar sites, are addressed. In order to facilitate the integration of the agricultural DR programs into the electricity market, a mathematical formulation for agricultural demand response aggregator (ADRA) is suggested. The ADRA participates in the day‐ahead electricity market on behalf of the responsive farms. To overcome the price uncertainty of the electricity market, a robust optimization approach is addressed. This approach determines the robust decisions of farms in the worst‐case realizations of the uncertain electricity price. Regarding on‐farm solar sites located in rural areas, a data‐driven approach is used to estimate the solar power generation of a significant number of sites without needing to install costly communication and measurement infrastructures. Finally, the proposed approach is implemented on agricultural lands in the northeast of Iran. The numerical results show that the suggested approach provides day‐ahead peak shaving for the power systems meeting the crop's water requirements. 相似文献
7.
Khalil Mokhtari Abdelhafid Elhadri Mourad Abdelaziz 《International Journal of Adaptive Control and Signal Processing》2019,33(9):1359-1373
For a class of nonlinear systems with the representation {A(x), B(x), C} and where the system parameters and dynamics are unknown, a simple adaptive synergetic controller ensuring the asymptotic convergence of the system to a desired manifold is proposed based on the technique of simple adaptive control (SAC). It is well known that the design of the synergetic control (SC) law requires a thorough knowledge of the system parameters and dynamics. Such problem obstructs the synthesis of the SC law and the designer is prompted to pass through the estimation methods, which, in turn, poses a problem of increasing the computation time of the control algorithm. To cope with this problem, a solution is proposed by modifying the original SC law to develop an SAC‐like adaptive SC law without the need of prior knowledge of the system. The stability of the proposed adaptive controller is formally proven via the Lyapunov approach. Experimental application to a quadrotor system is given to validate the theoretical results. 相似文献
8.
Rauf Tavakoli Bakhshi Puyan Mirarab Meysam Shahbazi Khalil 《Theoretical Foundations of Chemical Engineering》2020,54(5):995-1004
Theoretical Foundations of Chemical Engineering - In this work, with the aim of accurate prediction of water content, H2S and CO2 absorption capacity of diethanolamine (DEA) solvent in Khangiran... 相似文献
9.
10.
Noor-Ul-Ain Babar Yasir Faheem Joya Hassan Khalil Fayyaz Hussain Khurram Saleem Joya 《International Journal of Hydrogen Energy》2021,46(11):7885-7902
Developing only Fe derived bifunctional overall water splitting electrocatalyst both for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) while performing at low onset overpotential and with high catalytic stability is a rare instance. We present here the first demonstration of unique iron-oxide nanobeads (FeOx-NBs) based electrocatalyst executing both OER and HER with high activity. Thin-film electrocatalytic FeOx-NBs assembly is surface grown via simple spray coating (SC). The unique SC/FeOx-NBs propels OER initiating water oxidation just at 1.49 VRHE (η = 260 mV) that is the lowest observable onset potential for OER on simple Fe-oxide based catalytic films reported so far. Catalyst also reveals decently high HER activity and competent overall water splitting performance in the FeOx-NBs two-electrode system as well. Catalyst also presents stable kinetics, with promising high electrochemically active surface area (ECSA) of 1765 cm2, notable Tafel slopes of just 54 mV dec1? (OER) and 85 mV dec1? (HER), high exchange current density of 1.10 mA cm2? (OER), 0.58 mA cm2? (HER) and TOF of 74.29s1?@1.58VRHE, 262s1?@1.62VRHE (OER) and 82.5s1?@-0.45VRHE, 681s1?@-0.56VRHE (HER). 相似文献