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41.
Genetic Algorithms (GAs) have been applied as an effective optimization search technique in various fields, including the field of control design. In this paper, a new control method using GAs is proposed to attenuate the responses of a structure under seismic excitation. The proposed controller uses the state-space reconstruction technique based on the embedding theorem to obtain full-state performance from the available reduced order feedback. The parameters of the new controller are optimized using GAs. The proposed GA-based control method is verified on a benchmark problem—active mass driver system, and the results are compared with other control methods. The robustness of the proposed control method is also examined. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
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Garrett A. Mitchell Daniel L. Orange Jamshid J. Gharib Paul Kennedy 《Marine Geophysical Researches》2018,39(1-2):323-347
Marine seep hunting surveys are a current focus of hydrocarbon exploration surveys due to recent advances in offshore geophysical surveying, geochemical sampling, and analytical technologies. Hydrocarbon seeps are ephemeral, small, discrete, and therefore difficult to sample on the deep seafloor. Multibeam echosounders are an efficient seafloor exploration tool to remotely locate and map seep features. Geophysical signatures from hydrocarbon seeps are acoustically-evident in bathymetric, seafloor backscatter, midwater backscatter datasets. Interpretation of these signatures in backscatter datasets is a fundamental component of commercial seep hunting campaigns. Degradation of backscatter datasets resulting from environmental, geometric, and system noise can interfere with the detection and delineation of seeps. We present a relative backscatter intensity normalization method and an oversampling acquisition technique that can improve the geological resolvability of hydrocarbon seeps. We use Green Canyon (GC) Block 600 in the Northern Gulf of Mexico as a seep calibration site for a Kongsberg EM302 30 kHz MBES prior to the start of the Gigante seep hunting program to analyze these techniques. At GC600, we evaluate the results of a backscatter intensity normalization, assess the effectiveness of 2X seafloor coverage in resolving seep-related features in backscatter data, and determine the off-nadir detection limits of bubble plumes using the EM302. Incorporating these techniques into seep hunting surveys can improve the detectability and sampling of seafloor seeps. 相似文献
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Jamshid Hassanzadeh Daniel F. Stockli Brian K. Horton Gary J. Axen Lisa D. Stockli Marty Grove Axel K. Schmitt J. Douglas Walker 《Tectonophysics》2008,451(1-4):71-96
Eurasia has largely grown to its present enormous size through episodic addition of crustal blocks by recurring birth and demise of oceans such as Paleotethys and Neotethys. Excluding the Kopet Dagh Mountains in the northeast, crystalline basement rocks of various dimensions are exposed in all continental tectonic zones of Iran. These rocks have traditionally been viewed as continental fragments with Gondwanan affinity and summarily been assigned Precambrian or younger ages, despite the fact that evidence from isotopic dating has largely been lacking. This study presents new ion microprobe and thermal-ionization zircon U-Pb geochronological data from granitoids and orthogneisses from several locations in central Iran and the Sanandaj–Sirjan structural zones to determine crystallization ages and investigate the origin and continental affinity of these various crustal fragments. The resulting U-Pb crystallization ages for the granites and orthogneisses range from late Neoproterozoic to Early Cambrian, matching the mostly juvenile Arabian–Nubian shield and Peri-Gondwanan terranes constructed after the main phase of Pan-African orogenesis. TIMS analyses of zircons with inherited cores from western Iran suggest that the Neoproterozoic crust of Iran might not be entirely juvenile, pointing to the potential presence of inherited older Proterozoic components as is common in the eastern Arabian shield. More importantly, the new zircon U-Pb crystallization ages unequivocally demonstrate that crystalline basement underlying the Sanandaj–Sirjan zone, central Iran, and the Alborz Mountains is composed of continental fragments with Gondwanan affiliation, characterized by wide spread late Neoproterozoic subduction-related magmatism. The exposure of these late Neoproterozoic–Early Cambrian basement rocks in the Iranian regions north of the Zagros is structurally controlled and linked to both large-scale crustal extension and exhumation during Mesozoic and Tertiary time as well as Tertiary collisional tectonics associated with the closure of Neotethys. 相似文献
44.
Farsi Mohammad Mohamadian Nima Ghorbani Hamzeh Wood David A. Davoodi Shadfar Moghadasi Jamshid Ahmadi Alvar Mehdi 《Natural Resources Research》2021,30(5):3455-3481
Natural Resources Research - Accurate prediction of pore-pressures in the subsurface is paramount for successful planning and drilling of oil and gas wellbores. It saves cost and time and helps to... 相似文献
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This paper presents a design‐variable‐based inelastic hysteretic model for beam–column connections. It has been well known that the load‐carrying capacity of connections heavily depends on the types and design variables even in the same connection type. Although many hysteretic connection models have been proposed, most of them are dependent on the specific connection type with presumed failure mechanisms. The proposed model can be responsive to variations both in design choices and in loading conditions. The proposed model consists of two modules: physical‐principle‐based module and neural network (NN)‐based module in which information flow from design space to response space is formulated in one complete model. Moreover, owing to robust learning capability of a new NN‐based module, the model can also learn complex dynamic evolutions in response space under earthquake loading conditions, such as yielding, post‐buckling and tearing, etc. Performance of the proposed model has been demonstrated with synthetic and experimental data of two connection types: extended‐end‐plate and top‐ and seat‐angle with double‐web‐angle connection. Furthermore, the design‐variable‐based model can be customized to any structural component beyond the application to beam–column connections. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
47.
This paper describes a three-dimensional discrete element method of analysis for granular materials. Individual particles are modelled as rigid, six-sided solids with six degrees of freedom. Various types of contacts are possible among the three-dimensional discrete elements. Models for these contact types are described. Computational aspects of the method, such as techniques for contact detection and data structure, are addressed. Selective results of three examples that demonstrate the application of the method to granular flow problems are presented and discussed. 相似文献
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Jamshid Shahabpour 《Resource Geology》2010,60(1):109-115
Feedback, one of the most fundamental processes existing in nature, is present in almost all dynamic systems. Feedback concepts have been utilized almost exclusively by engineers. Nevertheless, this theory is applicable to formulating and solving problems in geology, particularly in the ore-forming systems. Feedback is distinctly operative in the generation of two groups of mineral deposits: (i) Mineral deposits showing rhythmic structures/textures, such as layered chromite deposits, re-opened veins with banded structure/texture, Mississippi Valley-type deposits with alternate bands/crusts of barite and galena, proximal volcanogenic massive sulfide deposits with mineralized layers of breccia clasts, and banded iron formations with alternate silica and magnetite and/or hematite bands, and (ii) mineral deposits lacking visible rhythmic structures/textures, but showing evidence of rhythmic process(es), such as in porphyry base metal deposits. There is an alternation of positive and negative feedback mechanisms in the ore-forming systems discussed here, which implies the involvement of feedback loops of negative sign. 相似文献