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排序方式: 共有1681条查询结果,搜索用时 31 毫秒
21.
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
22.
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
23.
Masoud Zarifneshat Pejman Khadivi 《Journal of Network and Computer Applications》2013,36(3):1078-1090
In order to evaluate performance of protocols for ad hoc networks, the protocols have to be tested under realistic conditions. These conditions may include a reasonable transmission range, a limited buffer size, and realistic movement of mobile users (mobility models). In this paper, we propose a new and realistic type of random mobility models in which the mobile node has to decelerate to reach the point of direction change and accelerates with a defined acceleration to reach its intended speed. This realistic mobility model is proposed based on random mobility models. In reality, mobile objects tend to change their speed when they are going to change their direction, i.e. decelerate when approaching a direction change point and accelerate when they start their movement in a new direction. Therefore, in this paper, we implement this behavior in random mobility models which lack such specification. In fact, this paper represents our effort to use this accelerated movement to anticipate a probable direction change of a mobile node with reasonable confidence. The simulation type of this paper is based on traces produced by a mobility trace generator tool. We use a data mining concept called association rule mining to find any possible correlations between accelerated movement of mobile node and the probability that mobile node wants to change its direction. We calculate confidence and lift parameters for this matter, and simulate this mobility model based on random mobility models. These simulations show a meaningful correlation between occurrence of an accelerated movement and event of mobile node's direction change. 相似文献
24.
Masoud Hajarian 《国际自动化与计算杂志》2013,10(5):481-486
Linear matrix equations are encountered in many systems and control applications.In this paper,we consider the general coupled matrix equations(including the generalized coupled Sylvester matrix equations as a special case)l t=1EstYtFst = Gs,s = 1,2,···,l over the generalized reflexive matrix group(Y1,Y2,···,Yl).We derive an efcient gradient-iterative(GI) algorithm for fnding the generalized reflexive solution group of the general coupled matrix equations.Convergence analysis indicates that the algorithm always converges to the generalized reflexive solution group for any initial generalized reflexive matrix group(Y1(1),Y2(1),···,Yl(1)).Finally,numerical results are presented to test and illustrate the performance of the algorithm in terms of convergence,accuracy as well as the efciency. 相似文献
25.
Increasingly, software systems are constructed by integrating and composing multiple existing applications. The resulting complexity increases the need for self-management of the system. However, adding autonomic behavior to composite systems is difficult, especially when the constituent components are heterogeneous and they were not originally designed to support such interactions. Moreover, entangling the code for self-management with the code for the business logic of the original applications may actually increase the complexity of the systems, counter to the desired goal. In this paper, we address autonomization of composite systems that use CORBA, one of the first widely used middleware platforms introduced more than 17 years ago that is still commonly used in numerous systems. We propose a model, called Adaptive CORBA Template (ACT), that enables autonomic behavior to be added to CORBA applications automatically and transparently, that is, without requiring any modifications to the code implementing the business logic of the original applications. To do so, ACT uses “generic” interceptors, which are added to CORBA applications at startup time and enable autonomic behavior to be introduced later at runtime. We have developed ACT/J, a prototype of ACT in Java. We describe a case study in which ACT/J is used to introduce three types of autonomic behavior (self-healing, self-optimization, and self-configuration) to a distributed surveillance application. 相似文献
26.
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
27.
Multidisciplinary design optimization of a small solid propellant launch vehicle using system sensitivity analysis 总被引:2,自引:1,他引:1
Jahangir Jodei Masoud Ebrahimi Jafar Roshanian 《Structural and Multidisciplinary Optimization》2009,38(1):93-100
Multidisciplinary design optimization approaches have significant effects on aerospace vehicle design methodology. In designing
next generation of space launch systems, MDO processes will face new and greater challenges. This study develops a system
sensitivity analysis method to optimize multidisciplinary design of a two-stage small solid propellant launch vehicle. Suitable
design variables, technological, and functional constraints are considered. Appropriate combinations of disciplines such as
propulsion, weight, geometry, and trajectory simulation are used. A generalized sensitivity equation is developed and solved.
These results are basis for optimization. Comparison of the developed approach with gradient optimization methods reveals
that developed approach requires less computation time. 相似文献
28.
Masoud Alahbakhshi Aditya Mishra Grigorii Verkhogliadov Emigdio E. Turner Ross Haroldson Austen C. Adams Qing Gu Jeffrey J. Rack Jason D. Slinker Anvar A. Zakhidov 《Advanced functional materials》2023,33(28):2214315
Perovskite light-emitting diodes (PeLEDs) are advancing because of their superior external quantum efficiencies (EQEs) and color purity. Still, additional work is needed for blue PeLEDs to achieve the same benchmarks as the other visible colors. This study demonstrates an extremely efficient blue PeLED with a 488 nm peak emission, a maximum luminance of 8600 cd m−2, and a maximum EQE of 12.2% by incorporating the double-sided ethane-1,2-diammonium bromide (EDBr2) ligand salt along with the long-chain ligand methylphenylammonium chloride (MeCl). The EDBr2 successfully improves the interaction between 2D perovskite layers by reducing the weak van der Waals interaction and creating a Dion–Jacobson (DJ) structure. Whereas the pristine sample (without EDBr2) is inhibited by small stacking number (n) 2D phases with nonradiative recombination regions that diminish the PeLED performance, adding EDBr2 successfully enables better energy transfer from small n phases to larger n phases. As evidenced by photoluminescence (PL), scanning electron microscopy (SEM), and atomic force microscopy (AFM) characterization, EDBr2 improves the morphology by reduction of pinholes and passivation of defects, subsequently improving the efficiencies and operational lifetimes of quasi-2D blue PeLEDs. 相似文献
29.
30.
Ali Eshaghi Mohammad Mashreghi Mahere Rezazade Bazaz Masoud HomayouniTabrizi Majid Darroudi 《IET nanobiotechnology / IET》2017,11(5):517
The aim of this study is to introduce natural‐based polymers, chitosan and starch, to design a remedial nanocomposite, comprising of cerium oxide nanoparticles and silver nanoparticles, to investigate their effects in accelerating wound healing and in wound microbial load. Cerium oxide nanoparticles synthesized in starch solution added to the colloidal dispersion of synthesized silver nanoparticles in chitosan to make a three‐component nanomaterial. Mice were anaesthetized and two parallel full‐thickness round wounds were excised under aseptic conditions with the help of sterile dermal biopsy punch. Furthermore, effects of silver‐chitosan and silver‐cerium‐chitosan nanocomposite had evaluated on rate of wound closure and collagen density and on microbial load of wound in full‐thickness model. Results showed that both silver chitosan and silver‐cerium‐chitosan had significant impact on acceleration of wound closure and collagen content and on reduction of wound microbial load in comparison with control group, which was, received no treatments. However, the silver‐cerium‐chitosan nanocomposite is more potent than silver‐chitosan group and control group in wound closure. The wound healing effects of silver‐cerium‐chitosan nanocomposite are due to unique features of its three components and this nanocomposite promises impressive remedies for clinical application.Inspec keywords: wounds, nanocomposites, nanomedicine, nanoparticles, proteins, cerium, silver, polymers, colloids, patient treatmentOther keywords: biopolymer‐based nanocomposite wound dressing, wound healing properties, wound microbial load, natural‐based polymers, chitosan, remedial nanocomposite, cerium oxide nanoparticles, nanoceria, silver nanoparticles, starch solution, three‐component nanomaterial, synthesised silver nanoparticles, ketamine intraperitoneal injection, silver‐cerium‐chitosan nanocomposite, wound closure, collagen density, wound healing effects, wound care, aseptic conditions, sterile dermal biopsy punch, Ag‐Ce 相似文献