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排序方式: 共有337条查询结果,搜索用时 46 毫秒
1.
Pressure-assisted infiltration was used to synthesize SiC/Al 6061 composites containing high weight percentages of SiC. A combination of PEG and glass water was used to fabricate SiC preforms and the effect of the presence of glass water on the microstructure and mechanical properties of the preforms was evaluated by performing compression tests on the preforms. Also, the compressive strength and the hardness of the SiC/Al composites were investigated. The results revealed that the glass water improved the compressive strength of the preforms by about five times. The microstructural characterization of the composites showed that the penetration of the aluminum melt into the preforms was completed and almost no porosity could be seen in the microstructures of the composites. Moreover, the composite containing 75 wt% SiC exhibited the highest compressive strength as well as the maximum hardness. The results of the wear tests showed that increasing the SiC content reduces the wear rate so that the Al-75 wt% SiC composite has a lower wear rate and a lower coefficient of friction than those of Al-67 wt% SiC composite. This indicated higher wear resistance in these composites than the Al alloy due to the formation of a tribological layer on the surface of the composites. 相似文献
2.
Zahra Kiarsi Mohammad Hojjati Behrooz Alizadeh Behbahani Mohammad Noshad 《Journal of Food Safety》2020,40(3):e12782
Nutmeg (Myristica fragrans) seed was subjected to the hydro-distillation method to extract its essential oil (NEO). Its main constituents were α-pinene (20.16%), sabinene (14.45%), and β-pinene (13.26%) with great antimicrobial and antioxidant actions. A novel edible coating was then fabricated based on the sage seed mucilage (SSM) and NEO, to ameliorate the quality and shelf-life of beef slices. The NEO-loaded SSM coating was able to significantly decrease the population of total viable count, Escherichia coli, Staphylococcus aureus, psychrotrophic bacteria, and fungi. Moreover, lipid oxidation of beef slices was remarkably suppressed upon the application of bioactive NEO-loaded SSM edible coating, as compared with the control by Day 6. The coated beef sample, especially NEO-rich SSM coated ones perceived a higher consumer acceptance and firmness than the SSM coated and noncoated samples. The SSM edible coating containing NEO could therefore have the potential to control the growth of pathogenic microorganisms and lipid oxidation, and to improve the color stability and sensory properties of meat and meat products. 相似文献
3.
An experimental study of a cross-flow type plate heat exchanger for dehumidification/cooling 总被引:1,自引:0,他引:1
The thermal and dehumidification behaviour of a standard cross-flow type plate heat exchanger, intended for use as a dehumidifier/cooler, has been investigated both experimentally and numerically. Three sets of experiments have been carried out where air is blown into the primary and secondary sides of the exchanger, while water and liquid desiccant were being sprayed in a counter flow arrangement. The first set represents the indirect evaporative cooling of the primary stream by the secondary air stream. The second set is with liquid desiccant only and no indirect evaporative cooling. In the third set of experiments the primary air stream is indirectly evaporatively cooled by the secondary air stream and dehumidified by the liquid desiccant sprayed into the primary side of the exchanger. The above experiments indicate that the heat exchanger performs well when used with liquid desiccant. Furthermore, for an exchanger angle of 45°, there is an optimum value of air mass flow rate at which the effectiveness and dehumidification efficiency of the plate heat exchanger are maxima. To investigate the effect of the ambient air conditions on the PHE performance, further experiments were carried out using a heater element and a humidifier. The results show that under laboratory conditions the exchanger effectiveness and dehumidification efficiency increase with increasing primary air inlet temperature and humidity ratio. The experimental results were used to validate a computer model developed for the cross-flow type plate heat exchanger/dehumidifier. Comparison indicates that the numerical results are in good agreement with the experiments. 相似文献
4.
Nima Alizadeh Asha-Dee N. Celestine Maria L. Auad Vinamra Agrawal 《Polymer Engineering and Science》2021,61(5):1299-1309
The stress relaxation behavior of acrylic–polyurethane (PU)-based graft-interpenetrating polymer networks (IPNs) was characterized via dynamic mechanical analysis (DMA) and modeled using finite element method (FEM) analysis. Stress relaxation of glassy IPN specimens was experimentally studied under flexural testing, while rubbery IPN specimens were tested in tension. The effects of varying the styrene content in the acrylic copolymer phase, compatibility of the two phases in IPNs, and changing the concentration of acrylic copolymer and PU were studied. A higher percentage of styrene content resulted in higher homogeneity of IPN specimens, and decrease in initial modulus for acrylic copolymer specimens. Additionally, glassy IPN specimens with 90% styrene shows resistance to relaxation as high as acrylic copolymer samples. Experimental results were used to develop a numerical model to study stress relaxation response of specimens. While polymer systems have been studied computationally, numerical modeling of IPN systems is still in its infancy. A three-dimensional FEM model was developed using the Generalized Maxwell model and four-term Prony series constants, which were extracted from the stress relaxation experiments. With four terms in the Prony series, a good match was observed between experimental observations and results from the FEM model. 相似文献
5.
Majid Alizadeh Moghadam Reza Mohammadi Ehsan Sadeghi Mohammad Amin Mohammadifar Mohammad Nejatian Maryam Fallah Milad Rouhi 《应用聚合物科学杂志》2021,138(28):50672
The effects of gum tragacanth obtained from two species of Astragalus Gossypinus (GT-G) and A. Parrowianus (GT-P) at two levels of 10% and 30% combined with cellulose nanofibers (CNF; 5%) on the physico-mechanical and structural properties of polyvinyl alcohol (PVA) nanocomposite film were investigated in this study. The water solubility and water vapor permeability of the films decreased with increasing the content of both gums, especially in the film containing 30% GT-P. The highest values of the tensile strength (39.3 MPa) and elongation at break (445%) belonged to the treatment containing 10% GT-P (90/10P/0). The FTIR and DSC analyses confirmed good interactions between GT and PVA in the 90/10P/0 treatment. SEM images indicated the dense structure of this film as the optimum treatment. Although the presence of CNF in the films containing GT-G improved some properties, especially the Young modulus, it impaired all the functional properties of nanocomposite GT-P film. 相似文献
6.
Mohammad Ali Badamchizadeh Sohrab Khanmohammadi Gasem Alizadeh Ali Aghagolzade 《International Journal of Control, Automation and Systems》2009,7(3):331-339
Considering an infinite number of eigenvalues for time delay systems, it is difficult to determine their stability. We have
developed a new approach for the stability test of time delay nonlinear hybrid systems. Construction of Lyapunov functions
for hybrid systems is generally a difficult task, but once these functions are found, stability’s analysis of the system is
straight-forward. In this paper both delay-independent and delay-dependent stability tests are proposed, based on the construction
of appropriate Lyapunov-Krasovskii functionals. The methodology is based on the sum of squares decomposition of multivariate
polynomials and the algorithmic construction is achieved through the use of semidefinite programming. The reduction techniques
provide numerical solution of large-scale instances; otherwise they will be computationally infeasible to solve. The introduced
method can be used for hybrid systems with linear or nonlinear vector fields. Finally simulation results show the correctness
and validity of the designed method.
Recommended by Editorial Board member Young Soo Suh under the direction of Editor Jae Weon Choi. The authors wish to express
their thanks to Dr. A. Papachristodoulou and Dr. M. Peet for their helpful comments and suggestions.
Mohammad Ali Badamchizadeh was born in Tabriz, Iran, in December 1975. He received the B.S. degree in Electrical Engineering from University of Tabriz
in 1998 and the M.Sc. degree in Control Engineering from University of Tabriz in 2001. He received the Ph.D. degree in Control
Engineering from University of Tabriz in 2007. He is now an Assistant Professor in the Faculty of Electrical and Computer
Engineering at University of Tabriz. His research interests include Hybrid dynamical systems, Stability of systems, Time delay
systems, Robot path planning.
Sohrab Khanmohammadi received the B.S. degree in Industrial Engineering from Sharif University, Iran in 1977 and the M.Sc. degree in Automatic
from University Paul Sabatie, France in 1980 and the Ph.D. degree in Automatic from National University, ENSAE, France in
1983. He is now a Professor of Electrical Engineering at University of Tabriz. His research interests are Fuzzy control, Artificial
Intelligence applications in control and simulation on industrial systems and human behavior.
Gasem Alizadeh was born in Tabriz, Iran in 1967. He received the B.S. degree in Electrical Engineering from Sharif University, Iran in 1990
and the M.Sc. degree from Khajeh Nasir Toosi University, Iran in 1993 and the Ph.D. degree in Electrical Engineering from
Tarbiat Modarres University, Iran in 1998. From 1998, he is a Member of University of Tabriz in Iran. His research interests
are robust and optimal control, guidance, navigation and adaptive control.
Ali Aghagolzadeh was born in Babol, Iran. He received the B.S. degree in Electrical Engineering in 1985 from University of Tabriz, Tabriz,
Iran, and the M.Sc. degree in Electrical Engineering in 1988 from the Illinois Institute of Technology, Chicago, IL. He also
attended the School of Electrical Engineering at Purdue University in August 1998 where he was also employed as a part-time
research assistant and received the Ph.D. degree in 1991. He is currently an Associate Professor of Electrical Engineering
at University of Tabriz, Tabriz, Iran. His research interests include digital signal and image processing, image coding and
communication, computer vision, and image analysis. 相似文献
7.
Fracture investigation of U‐notch made of tungsten–copper functionally graded materials by means of strain energy density
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H. Mohammadi H. Salavati Y. Alizadeh A. Abdullah F. Berto 《Fatigue & Fracture of Engineering Materials & Structures》2017,40(12):1984-1993
The averaged strain energy density over a well‐defined control volume was employed to assess the fracture of U‐notched specimens made of tungsten–copper functionally graded materials under prevalent mode II loading. The boundary of control volume was evaluated by using a numerical method. Power law function was employed to describe the mechanical properties (elasticity modulus, Poisson's ratio, fracture toughness and ultimate tensile stress) through the specimen width. The effect of notch tip radius and notch depth on notch stress intensity factors and mode mixity parameter χ were assessed. In addition, a comparison based on fracture load between functionally graded and homogeneous W–Cu was made. Furthermore, in this research, it was shown that the mean value of the strain energy density over the control volume can be accurately determined using coarse meshes for functionally graded materials. 相似文献
8.
We propose an adaptive neuro‐fuzzy inference system (ANFIS) for stock portfolio return prediction. Previous work has shown that portfolio optimization can be improved by using predicted stock earnings rather than historical earnings. We show that predicted portfolio returns can be improved by using ANFIS and taking as input a variety of technical and fundamental attributes about various indices of the stock market. To generate membership functions, we use a robust noise rejection‐clustering algorithm. The neuro‐fuzzy model is tested on portfolios constituted from the Tehran Stock Exchange. In our experiments, the proposed method performs better in predicting the portfolio return than the classical Markowitz portfolio optimization method, a multiple regression, a neural network, and the Sugeno–Yasukawa method. © 2010 Wiley Periodicals, Inc. 相似文献
9.
Farzad Hashemzadeh Iraj Hassanzadeh Mahdi Tavakoli Ghasem Alizadeh 《Journal of Intelligent and Robotic Systems》2012,68(3-4):245-259
In this paper, we introduce a new adaptive controller design scheme for nonlinear telerobotic systems with varying time delays where the delays and their variation rates are unknown. The designed controller has the ability to synchronize the state behaviors of the local and the remote robots. In this paper, asymptotic stability in the presence of varying time delays is of interest. Using the proposed controller, asymptotic stability of the bilateral telerobotic system subject to any bounded yet unknown varying delay with a bounded yet unknown rate of change can be guaranteed. Besides the varying time delay, the proposed adaptive controller has the ability to adapt to the parameter variations in the local and the remote robots’ dynamics. It is shown that position and velocity errors between the local and the remote manipulators converge to the zero asymptotically, thus ensuring teleoperation transparency. Experimental and simulation results with a pair of PHANToM haptic devices and a pair of planar manipulators under varying time delays in the communication channel demonstrate the effectiveness of the proposed scheme. 相似文献
10.