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21.
In this investigation, attempts have been made to study the inhibitive effect of N,N′-ortho-phenylen acetyle acetone imine (S1) and 4-[(3-{[1-(2-hydroxy phenyl) methylidene] amino} propyl) ethanemidol]-1,3-benzenediol (S2) in the concentration range of 50–400 ppm for mild steel with two different microstructures resulted from two different heat treatments (annealed (A) and quenched and tempered (Q&T)) in 1 M hydrochloric acid solution. Both Schiff bases acted as a mixed type inhibitors. The S1 inhibitor for both microstructures showed better inhibition efficiency than S2. The A samples indicated slightly less corrosion than Q&T samples in 1 M HCl solution in absence of inhibitor due to the formation of duplex γ-Fe2O3/Fe3O4. 相似文献
22.
In this research work, CuO nano-particles were synthesized at 750 °C (for 2 h) by the direct thermal-decomposition method using the brochantite as precursor. The nano-particles were characterized using X-ray diffraction (XRD), energy dispersive spectra (EDS), infrared spectrum (IR), and scanning electron microscope (SEM). SEM image showed that the CuO nano-particles were of rod shape with diameter and length of 235 ± 5 nm and 856 ± 5 nm, respectively. As a result, this method could be used at an industrial scale as a cheap and convenient way in production of pure tenorite nano-particles. 相似文献
23.
Distinguishing condition curve for radial gates 总被引:1,自引:0,他引:1
Identifying the free or submerged flow condition and the threshold between the two regimes is vital for accurate flow measurement through a gate. In this paper, analytical findings about distinguishing condition curve of radial gates are presented. The generality of the available calibration methods of the radial gates has been analyzed. Then, based on the assumption of starting the transition zone right at the interception point of the free and submerged flow relationships, a comprehensive equation is developed to distinguish the flow condition through a radial gate. Using ample high quality available experimental data, the accuracy of the proposed distinguishing curve was verified. The results indicated that the proposed distinguishing curve accurately identified observed flow condition data. Finally, by defining a suitable sensitivity index, the effects of downstream channel width, energy loss through the gate, Reynolds number, and contraction coefficient on the distinguishing condition curve have been evaluated. Also, the results promise the application of the proposed method for situations where only one of some parallel radial gates is operating under the submerged flow condition. 相似文献
24.
Diagrids are known as an esthetically pleasing and structurally efficient system. The current design codes and provisions, however, provide no specific guidelines for their design under extreme events such as earthquakes. This paper presents a comprehensive investigation of the performance of steel diagrid structures to evaluate their key seismic performance factors. Nonlinear static, time‐history dynamic, and incremental dynamic analyses are used to assess diagrid performance and collapse mechanisms in a high seismic region. Seismic performance factors including response modification factor, ductility factor, overstrength factor, and deflection amplification factor are quantified using 4 different methodologies. Four archetype groups of diagrid buildings ranging in height from 4 to 30 stories have been investigated. An R factor in the range of 4 to 5 is recommended for steel diagrid frames in the range of 8 to 30 stories unless supplementary analyses are conducted to find the optimal diagonal angle. For low‐rise steel diagrids (under 8 stories), an R factor in the range of 3.5 to 4 is recommended. Further, an overstrength and ductility of 2.5 and 2 are recommended. This paper lays the groundwork for including steel diagrids in design provisions. 相似文献
25.
26.
In recent years, diagrid structures have received increasing attention among both designers and researchers of tall buildings for creating one‐of‐a‐kind signature structures. This paper presents a state‐of‐the‐art review of diagrid structures. First, various diagrid configurations, main factors affecting their behaviors, and related design parameters and approaches are discussed. Then, diagrid applications for free‐form steel and concrete structures are introduced showing the diagrid applicability for complex structures followed by recent advances in structural design of diagrid connections, diagrid nonlinear behavior, and structural control of diagrids. Recent studies about a new variation of tubular and diagrid systems, hexagrids, are discussed briefly. Finally, the diagrid potential in design of sustainable buildings is delineated. 相似文献
27.
Majidi Mir Reza Pournaghi-Azar Mohammad Hossein Saadatirad Afsaneh Alipour Esmaeel 《Food Analytical Methods》2015,8(4):1067-1077
Food Analytical Methods - This paper describes the use of a pencil lead electrode (PLE) covered by hemoglobin (Hb) through a simple and rapid electroless method for the electroreduction of hydrogen... 相似文献
28.
Micro electro-mechanical systems (MEMS) are increasingly being used in measurement and control problems due to their small
size, low cost, and low power consumption. The vibrating gyroscope is a MEMS device that will have a significant impact on
stability control systems in the transportation industry. This paper investigates the application of a modified model reference
adaptive control for MEMS gyroscope. Using this adaptive control algorithm, an estimation of the angular velocity and the
damping and stiffness coefficients in real time is easily computable. Changing the conventional model reference input makes
it feasible to utilize a low pass filter to remove unwanted oscillations caused by high adaptation gain. This new adaptive
control technique enables quick compensation for large changes in the system dynamics, providing consistent estimation of
gyroscope parameters including angular velocity and large robustness to parameter variations and external disturbances. The
asymptotic stability of the mentioned adaptive controller is guaranteed using the Lyapunov direct method. Numerical simulation
is presented to verify the effectiveness of the proposed control scheme. 相似文献
29.
Salman Movahedirad Asghar Molaei Dehkordi Esmaeel Abbaszade Molaei Mehdi Haghi Mohammad Banaei Johannes A. M. Kuipers 《化学工程与技术》2014,37(12):2096-2102
Bubble splitting in 2D gas‐solid freely bubbling fluidized beds is experimentally investigated using digital image analysis. The quantitative results can be applied for the development of a new breakage model for bubbly fluidized beds, especially discrete bubble models. The variation of splitting frequency with bubble diameter, new resulting bubble volumes, positions, and also the assumptions of mass and momentum conservation for bubbles after breakage are studied in detail. Small bubbles are found to be more stable than large ones and nearly all mother bubbles split into two almost equally sized daughter bubbles. The momentum of gas bubbles in the vertical direction remains approximately constant after breakage, whereas that of bubbles in the horizontal direction changes with no clear trend. The effect of fluidizing gas velocity in breakage frequency is also examined. 相似文献
30.
M. Barfeie Ali R. Soheili Maryam Arab Ameri 《Engineering Analysis with Boundary Elements》2013,37(12):1567-1575
In this paper, a two-dimensional variational mesh generation method is applied to obtain adaptive centers for radial basis functions (RBFs). At first, a set of uniform centers is distributed in the domain, then mesh generation differential equations are used to move the centers to region with high gradients. An iterative algorithm is introduced to solve steady-state mesh generation differential equations with RBFs. Functions with steep variation in the domains are used to validate the adaptive centers generation method. In addition to the centers adaption process is applied to solve elliptic partial differential equations via RBFs collocation method. Numerical results of Helmholtz differential equation show a clear reduction in the error, when the adaptive centers are used for RBFs. 相似文献