211 research outputs found
The Exterior and Interior World of The Qing Calligrapher Yi Bingshou
Honors (Bachelor's)History of ArtUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/120574/1/linyic.pd
UbiquitināIndependent Entry into the Yeast Recycling Pathway
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92023/1/j.1600-0854.2002.030204.x.pd
Output Feedback Fractional-Order Nonsingular Terminal Sliding Mode Control of Underwater Remotely Operated Vehicles
For the 4-DOF (degrees of freedom) trajectory tracking control problem of underwater remotely operated vehicles (ROVs) in the presence of model uncertainties and external disturbances, a novel output feedback fractional-order nonsingular terminal sliding mode control (FO-NTSMC) technique is introduced in light of the equivalent output injection sliding mode observer (SMO) and TSMC principle and fractional calculus technology. The equivalent output injection SMO is applied to reconstruct the full states in finite time. Meanwhile, the FO-NTSMC algorithm, based on a new proposed fractional-order switching manifold, is designed to stabilize the tracking error to equilibrium points in finite time. The corresponding stability analysis of the closed-loop system is presented using the fractional-order version of the Lyapunov stability theory. Comparative numerical simulation results are presented and analyzed to demonstrate the effectiveness of the proposed method. Finally, it is noteworthy that the proposed output feedback FO-NTSMC technique can be used to control a broad range of nonlinear second-order dynamical systems in finite time
Multi-Fidelity Space Mission Planning and Infrastructure Design Framework for Space Resource Logistics
To build a sustainable and affordable space transportation system for human
space exploration, the design and deployment of space infrastructures are
critical; one attractive and promising infrastructure system is the in-situ
resource utilization (ISRU) system. The design analysis and trade studies for
ISRU systems require the consideration of not only the design of the ISRU plant
itself but also other infrastructure systems (e.g., storage, power) and various
ISRU architecture options (e.g., resource, location, technology). This paper
proposes a system-level space infrastructure and its logistics design
optimization framework to perform architecture trade studies. A new space
infrastructure logistics optimization problem formulation is proposed that
considers infrastructure subsystems' internal interactions and their external
synergistic effects with space logistics simultaneously. Since the full-size
version of this proposed problem formulation can be computationally
prohibitive, a new multi-fidelity optimization formulation is developed by
varying the granularity of the commodity type definition over the network
graph; this multi-fidelity formulation can find an approximation solution to
the full-size problem computationally efficiently with little sacrifice in the
solution quality. The proposed problem formulation and method are applied to a
multi-mission lunar exploration campaign to demonstrate their values.Comment: 34 pages, 3 figures, presented at the AIAA Propulsion and Energy
Forum 2019, submitted to the Journal of Spacecraft and Rocket
Fuzzy Classification of High Resolution Remote Sensing Scenes Using Visual Attention Features
In recent years the spatial resolutions of remote sensing images have been improved greatly. However, a higher spatial resolution image does not always lead to a better result of automatic scene classification. Visual attention is an important characteristic of the human visual system, which can effectively help to classify remote sensing scenes. In this study, a novel visual attention feature extraction algorithmwas proposed,which extracted visual attention features through amultiscale process. And a fuzzy classification method using visual attention features (FC-VAF) was developed to performhigh resolution remote sensing scene classification. FCVAF was evaluated by using remote sensing scenes from widely used high resolution remote sensing images, including IKONOS, QuickBird, and ZY-3 images. FC-VAF achieved more accurate classification results than the others according to the quantitative accuracy evaluation indices.We also discussed the role and impacts of different decomposition levels and different wavelets on the classification accuracy. FC-VAF improves the accuracy of high resolution scene classification and therefore advances the research of digital image analysis and the applications of high resolution remote sensing imagesThis paper was supported by the National Natural Science
Foundation of China (Grant no. 41371343)
Super-resolution mapping of wetland inundation from remote sensing imagery based on integration of back-propagation neural network and genetic algorithm
Mapping the spatio-temporal characteristics of wetland inundation has an important significance to the study of wetland environment and associated flora and fauna. High temporal remote sensing imagery is widely used for this purpose with the limitations of relatively low spatial resolutions. In this study, a novel method based on integration of back-propagation neural network (BP) and genetic algorithm (GA), so-called IBPGA, is proposed for super-resolution mapping of wetland inundation (SMWI) from multispectral remote sensing imagery. The IBPGA-SMWI algorithm is developed, including the fitness function and integration search strategy. IBPGA-SMWI was evaluated using Landsat TM/ETM + imagery from the Poyanghu wetland in China and the Macquarie Marshes in Australia. Compared with traditional SMWI methods, IBPGA-SMWI consistently achieved more accurate super-resolution mapping results in terms of visual and quantitative evaluations. In comparison with GA-SMWI, IBPGA-SMWI not only improved the accuracy of SMWI, but also accelerated the convergence speed of the algorithm. The sensitivity analysis of IBPGA-SMWI in relation to standard crossover rate, BP crossover rate and mutation rate was also carried out to discuss the algorithm performance. It is hoped that the results of this study will enhance the application of median-low resolution remote sensing imagery in wetland inundation mapping and monitoring, and ultimately support the studies of wetland environment.This paper was supported by the National Natural Science Foundation
of China (Grant No. 41371343 and Grant No. 41001255) and the scholarship
provided by the China Scholarship Council (Grant No.
201308420290)
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