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61.
Ayat Mehdi Kamali Abdoljabbar Mirzakuchaki Sattar 《Wireless Personal Communications》2019,108(2):1243-1259
Wireless Personal Communications - In this paper, a robust carrier recovery loop for high dynamic and weak signals in GPS receivers is proposed. To achieve optimal tracking performance at... 相似文献
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Amiri Aryan Dardel Morteza Daniali Hamidreza Mohammadi 《Multibody System Dynamics》2019,47(4):363-395
Multibody System Dynamics - In the current study, the dynamic behavior of two planar mechanisms with revolute joints, in the presence of clearances is investigated. Subsequently, a control scheme... 相似文献
64.
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Arezou Elahi Alireza Alfi Hamidreza Modares 《IEEE/CAA Journal of Automatica Sinica》2019,6(3):667-675
This paper presents a distributed control protocol for consensus control of multi-agent systems (MASs) under external disturbances and network imperfections, including communication delay and random packet dropout. To comply with the discrete nature of networked systems, in contrast to most of the existing work for MASs under network imperfections, the agents are modeled by discrete-time dynamics. The communication network is considered to be undirected, its delay is considered to be time-varying but bounded, and its packet dropout is modeled by a Bernoulli distributed white sequence. Sufficient conditions in terms of linear matrix inequalities (LMIs) for asymptotic mean-square consensus stability are derived under network imperfections without considering external disturbances. A desired disturbance attenuation level in the presence of both external disturbances and network imperfections is also provided. A simulation example is given to verify the effectiveness of the proposed approach in coping with network imperfection and disturbances. 相似文献
65.
Partial safety factors for resistance applied in the design equation of semi‐probabilistic formats can be obtained from the evaluation of a test database. These partial safety factors are influenced by two factors, the material uncertainty and the model uncertainty. This topic is covered in a former publication [1]. It includes the determination of a partial factor for the model uncertainty of unreinforced masonry shear walls. In this study the authors examine the next step, and calculate the partial factor of resistance applying the same method, as recommended i n EN 1990 – Annex D. In addition to the Coefficient of Variation (COV) for the model uncertainty, the calculation of the resistance partial factor considers deviations in geometry, as well as loading and material properties. The influence of the material uncertainty on structural performance is considered in the calculation by means of a weighted average of all COV values for various types of material properties, based on the number of relevant failure modes in the test database. In the last step, the resistance partial factors for models defined in DIN EN 1996‐1‐1/NA and DIN EN 1996‐1‐1/NA – Annex K are calculated by applying the probabilistic methods recommended in EN 1990 – Annex D and the model bias. 相似文献
66.
In the present work, Al-xB4C nanocomposite (x = 0, 1, 2, 3, 4 and 5 in wt%, having the average B4C size of 50 nm) were prepared using a high-energy ball mill. The milling times up to 16 h were applied. Then, the microstructural evolutions, mechanical properties, compressibility and sintering behavior of nanocomposites were investigated. The changes in powders morphology and microstructure during the milling process were characterized by laser diffraction particle size analyzer (LDA), SEM, XRD, EDS and TEM techniques. Compressibility and sintering behavior of milled powders compacted under different pressures (100–900 MPa) and at different sintering temperatures (500, 550 and 600 °C) were also studied. The pressing behavior of the nanocomposites was analyzed using linear compaction equations developed by Heckel, Panelli-Filho and Ge. The results showed the significant effects of B4C amounts and sintering temperatures on the compressibility and sintering behavior of nanocomposites. The increase in the B4C amount led to a decrease in both the compressibility rate and the sinterability of specimens. The maximum compression strength of 265 MPa and Vickers hardness of 165 VHN were obtained for Al-5 wt.% B4C nanocomposite milled for 16 h followed by sintering at 600 °C. 相似文献
67.
Moharramnejad Mojtaba Ehsani Ali Malekshah Rahime Eshaghi Shahi Mehrnaz Bavandpour Razieh Rajabi Hamidreza Mojab Seyyed Mohammadreza 《Journal of Materials Science: Materials in Electronics》2022,33(25):19693-19710
Journal of Materials Science: Materials in Electronics - This review gives an overview of the synthesis, surface, and electrochemical investigations over Mn-based compounds in the development of... 相似文献
68.
Javad Tousi Marzieh Kamali Iman Izadi Farid Sheikholeslam 《International Journal of Control, Automation and Systems》2018,16(6):2733-2742
In this paper a distributed adaptive dynamic surface controller is proposed for multi-agent systems under fixed directed graph topologies. The agents have uncertain nonlinear dynamics and are influenced by bounded unknown disturbances. The controller should synchronize the states of all agents with the corresponding states of the nonautonomous leader. It is proved that, with the proposed controller, the synchronization error remains bounded; and the bounds can be arbitrarily decreased by increasing the controller gains. The control rules are designed such that each agent only requires the state information of its neighbors, rendering a distributed control. The effectiveness of the proposed method is demonstrated through two simulation examples. 相似文献
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70.
Adriyan Milev Michael Wilson G.S. Kamali Kannangara Nguyen Tran 《Materials Chemistry and Physics》2008,111(2-3):346-350
The structure evolution to nanocrystalline graphite produced by ball milling in n-dodecane has been studied by Fourier analysis of broadened X-ray diffraction line profiles according to double-Voigt method. The Fourier analysis gave size and strain distributions of the coherently diffracting domains (X-ray crystallite size) and root-mean-square-strain (rmss) and their average values. The precursor graphite was defined by average crystal sizes of about hundreds of nanometers, measured along the in-plane and out-of-plane directions, and low rmss value of 0.38 × 10−3. During milling, the average crystallite sizes of graphite decreased to about 6 and 43 nm along the out-of-plane and in-plane directions, respectively. Correspondingly, the rmss of milled graphite increased to 6.54 × 10−3. Analysis of the out-of-plane to in-plane crystallite size ratios showed that the crystallites became progressively thinner and flatter. A linear relationship between rmss and reciprocal crystallite size along the stacking axis revealed that size of disordered boundary regions gradually increased at the expense of ordered crystalline regions. A model describing crystalline–nanocrystalline transformation of graphite along different crystallographic axis was formulated and used to discuss the experimental data. It was concluded that a distortion-controlled process is responsible for the crystalline–nanocrystalline transformation of graphite milled in n-dodecane. 相似文献