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1.
The effect of flow pulsations is studied via a discrete element model on hydrodynamics of spouted bed, which is being used in many important industries like drying processes. Decreased horizontal air percolation and preserving upward momentum, increased particle circulation, increased particle traverse distance, and better homogeneity are resulted from flow pulsations in spouted beds. Among the waveforms studied, square and triangular waveforms differ most and least from steady spouting, respectively. The predictions indicate that the pulsed spouted bed has the potential to enhance both gas and particle motion, hence being useful in drying and other operations. 相似文献
2.
Maysam Mohammadi Ali Yazdani Mohammad E. Bahrololoom Akram Alfantazi 《Journal of Coatings Technology and Research》2013,10(2):219-229
In this article, the effects of two inorganic corrosion inhibitors, permanganate and phosphate anions, on morphology, composition, thickness, and corrosion resistance of the anodic film formed on 2024 aluminum alloy in sulfuric acid were investigated. Surface morphology of the oxide films were studied by field emission scanning electron microscopy. Electrochemical impedance spectroscopy and potentiodynamic polarization tests were conducted to assess the corrosion resistance of the coatings. These analyses showed that the presence of the mentioned inhibitors changed the coating morphology, especially in the case of phosphate ions. Corrosion results indicated that using inhibitors during the anodizing process increased the corrosion resistance of the anodized samples. The increases were approximately 81% and 97% for 0.05 M of permanganate and phosphate ions, respectively, compared with the anodized coatings in the absence of additives. An increase in the inhibitor concentration results in better corrosion resistance of the aluminum anodic layer. 相似文献
3.
The term multipath routing means using multiple paths concurrently to transport data over network. The main problem of this routing scheme is the difference among the delays of selected paths, which causes reordering of a single flow's packets. In this paper, this problem is analyzed through a sociological perspective. We show that reordering problem is not inherently related to multipath routing, rather caused by the dominant capitalist view of the problem. then, the problem is addressed through a Marxism perspective. We theoretically prove that by this perspective, there exists a routing scheme that minimizes latency and also the requirement of buffering at receiver. 相似文献
4.
Maysam Abbasi Ehsan Abbasi Behrouz Tousi Gevork B. Gharehpetian 《International Journal of Circuit Theory and Applications》2019,47(10):1630-1644
This paper presents a new step-up switched-capacitor (SC) DC-DC converter which has many advantages such as reduction in investment cost, control complexity, number of components, voltage stress on components, and size over traditional topologies. In the proposed structure, power switches are reduced in number which in turn leads to the merits mentioned earlier and makes the converter more suitable for industrial applications. Furthermore, a previously introduced zero-current switching (ZCS) method is used here which provides soft switching for the devices. There is also a reduction in the number of required inductors to achieve ZCS due to the decreased number of switches in the proposed converter. The proposed converter is validated by comprehensive simulation results in MATLAB Simulink environment and also precise experimental results which show the acceptable performance of the proposed topology. 相似文献
5.
Axial compressive behavior of concrete actively confined by metal strips; part A: experimental study
Hasan Moghaddam Maysam Samadi Kypros Pilakoutas Saiid Mohebbi 《Materials and Structures》2010,43(10):1369-1381
This paper presents the results of an experimental study on the application of strapping technique for retrofit of concrete
compressive specimens. In this technique, standard strapping devices, which are used in the packaging industry, are applied
to post-tension high strength metal strips around the concrete columns. Experimental program included axial compressive tests
on 72 cylindrical and prismatic compressive specimens, which were actively confined by pre-stressed metal strips. The effects
of various parameters on strength and ductility of confined concrete were studied including compressive strength of concrete,
mechanical volumetric ratio of confining strips, post-tensioning force in the strip, number of strip layers wrapped around
the specimens and details of strip joint. The effects of strength and ductility of confining strips on the behavior of confined
specimens were also studied. Longitudinal and lateral strains of concrete and strain of the strips were monitored. Test results
showed significant increase in the strength and ductility of specimens due to active confinement by metal strips. It was observed
that ductility of confining material plays the most important role in enhancement of concrete ductility. The gain in strength
is strongly dependent to the effective mechanical volumetric ratio of confining strips. It was also observed that the active
confinement of concrete by post-tensioning the confining element results in stiffer pre-peak response of concrete specimens
than the usual passive confinement. 相似文献
6.
To investigate the heat transfer characteristics of a car radiator involved nanofluids, we used GAMBIT & FLUENT softwares and calculated the effective physical parameters using some famous models as a single‐phase mixture. Carbon nanotubes and boron nitride nanotubes have been used in less than 1% volume concentration in flat and twisted tubes. Our results show that nanofluids application in a twisted tube gives a great enhancement in the thermal performance in comparison of the flat tube. 相似文献
7.
Thermodynamic and Economic Optimization of Plate Fin Heat Exchangers Using the Bees Algorithm
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This study presents the successful application of the bees algorithm (BA) for optimal design of a cross‐flow plate fin heat exchanger by offset strip fins. The ε – NTU method is used to approximate the heat exchanger effectiveness and pressure drop. Two different objective functions including the minimization of total annual cost (sum of investment and operational costs) and total number of entropy generation units for certain heat duty required under given space constraints are considered as targets of optimization separately. Based on the applications, seven design parameters (heat exchanger length at hot and cold sides, fin height, fin frequency, fin thickness, fin‐strip length, and number of hot side layers) are selected as optimization variables. Two examples from the literature are presented to illustrate the efficiency and accuracy of the proposed algorithm. Results showed that the BA can detect an optimum configuration with higher speed (short computational time) and accuracy compared to the imperialist competitive algorithm (ICA) and the genetic algorithm (GA). © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res, 43(5): 427–446, 2014; Published online 3 October 2013 in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21087 相似文献
8.
We present a new noise shaping method and a dual-polarity calibration technique suited for successive approximation register type analog to digital converters (SAR–ADC). Noise is pushed to higher frequencies with the noise shaping by adding a switched capacitor. The SAR capacitor array mismatch has been compensated by the dual-polarity digital calibration with minimum circuit overhead. A proof-of-concept prototype SAR–ADC using the proposed techniques has been fabricated in a 0.5-μm standard CMOS technology. It achieves 67.7 dB SNDR at 62.5 kHz sampling frequency, while consuming 38.3 μW power with 1.8 V supply. 相似文献
9.
A review on pulsed flow in gas-solid fluidized beds and spouted beds: Recent work and future outlook
This paper reviews the application of pulsed flow in fluidized and spouted beds, widely used in various industries. A number of pulsing studies have been performed to improve the performance of these beds, enhance mixing and promote homogeneity. One effective way to increase the efficiency is to pulse the incoming flow, removing inactive or dead zones, thereby preventing agglomeration and settling. Although numerous studies have been carried out on conventional beds, little has been written on pulsed beds, in spite of their proven advantages. The role of pulsations in hydrodynamics, mixing, segregation, heat transfer, drying, and agglomeration are among the topics addressed. Future needs are identified and projected. 相似文献
10.
Maysam Mirahmadi Author VitaeAbdallah ShamiAuthor Vitae 《Computer Networks》2012,56(1):244-259
Hybrid optical-wireless networks provide the inexpensive broadband bandwidth, vital for modern applications, as well as mobility, and scalability required for an access network. However, in order to provide satisfactory Quality of Service (QoS) on such a non-homogeneous network, innovative designs are required.This paper proposes a novel scheduling mechanism to significantly improve the delay guarantee, while maintaining high-level throughput, by predicting the incoming traffic to optical network units (ONU). The proposed scheduler managed to exploit the available information in hybrid optical-wireless networks, to enhance the ONU scheduler. This results in accurate prediction of incoming traffic, which leads to intelligent and traffic-aware, scheduling and dynamic bandwidth assignment (DBA).Based on the proposed architecture, two DBA algorithms are proposed and their performance is evaluated by extensive simulations. Moreover, the maximum throughput of such network is analyzed. The results show that by using the proposed algorithms, the delay bound of delay-sensitive traffic classes can be decreased by a factor of two, without any adverse effect on the throughput. 相似文献