The problem of impact angle control guidance for a field-of-view constrained missile against non-maneuvering or maneuvering targets is solved by using the sliding mode control theory. The existing impact angle control guidance laws with field-of-view constraint are only applicable against stationary targets and most of them suffer abrupt-jumping of guidance command due to the application of additional guidance mode switching logic. In this paper, the field-of-view constraint is handled without using any additional switching logic. In particular, a novel time-varying sliding surface is first designed to achieve zero miss distance and zero impact angle error without violating the field-of-view constraint during the sliding mode phase. Then a control integral barrier Lyapunov function is used to design the reaching law so that the sliding mode can be reached within finite time and the field-of-view constraint is not violated during the reaching phase as well. A nonlinear extended state observer is constructed to estimate the disturbance caused by unknown target maneuver, and the undesirable chattering is alleviated effectively by using the estimation as a compensation item in the guidance law. The performance of the proposed guidance law is illustrated with simulations.
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http://dx.doi.org/10.1016/j.isatra.2015.12.018 | DOI Listing |
Phys Med Biol
January 2025
Department of Radiology, University of Chicago, 5841 South Maryland Avenue, Chicago, IL 60637, USA, Chicago, 60637, UNITED STATES.
Objective: Accurate image reconstruction from data with truncation in X-ray computed tomography (CT) remains a topic of research interest; and the works reported previously in the literature focus largely on reconstructing an image only within the scanning field-of-view (FOV). We develop algorithms to invert the data model with truncation for accurate image reconstruction within the entire subject support or a region slightly smaller than the subject support.
Methods: We formulate image reconstruction from data with truncation as an optimization program, which includes hybrid constraints on image total variation (TV) and image L1-norm for effectively suppressing truncation artifacts.
Int J Radiat Oncol Biol Phys
January 2025
Department of Radiation Oncology, University of Florida College of Medicine, Jacksonville, FL, USA.
Objectives: Radiotherapy manages pancreatic cancer in various settings; however, the proximity of gastrointestinal (GI) luminal organs-at-risk (OAR) poses challenges to conventional radiotherapy. Proton beam therapy (PBT) may reduce toxicities compared to photon therapy. This consensus statement summarizes PBT's safe and optimal delivery for pancreatic tumors.
View Article and Find Full Text PDFLight Sci Appl
January 2025
Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtzplatz 1, Eggenstein-Leopoldshafen, 76344, Germany.
The core advantage of metalenses over traditional bulky lenses lies in their thin volume and lightweight. Nevertheless, as the application scenarios of metalenses extend to the macro-scale optical imaging field, a contradiction arises between the increasing demand for large-aperture metalenses and the synchronous rise in design and processing costs. In response to the application requirements of metalens with diameter reaching the order of 10λ or even 10λ, this paper proposes a novel design method for fixed-height concentric-ring metalenses, wherein, under the constraints of the processing technology, a subwavelength 2D building unit library is constructed based on different topological structures, and the overall cross-section of the metalens is assembled.
View Article and Find Full Text PDFSci Rep
December 2024
The School of Automation Science and Electrical Engineering, Beihang University, Beijing, 100191, China.
The movement of biological swarms is widespread in nature, and collective behavior enhances a swarm's adaptability to its environment. However, most research focuses on free swarm movement, overlooking the impact of environmental constraints such as tubes. This study examines the swimming behavior of Petitella georgiae through a tube.
View Article and Find Full Text PDFBiomicrofluidics
December 2024
Shanghai Aurefluidics Technology Co. Ltd, Shanghai 201800, China.
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