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Set membership estimation applied to the localization of small UAS in tight flight formations
J. Bolting,S. Fergani 제어로봇시스템학회 2018 제어로봇시스템학회 국제학술대회 논문집 Vol.2018 No.10
This paper proposes a set membership approach for UAS (unmanned aerial system)localization in a tight flight formation. A novel set membership estimation strategy based on the typical hardware available for localization (due to the cost constraints put on small UAS for civil applications) is developed. The main idea is as follows: using time-differenced differential GNSS carrier phase observations, the relative position between UAS can be tracked with centimeter-level precision, but affected by an unknown constant meter-level bias due to the initial coarse position standalone position estimate. Using pseudorange observations, as well as UWB range observations, the guaranteed space containing this position bias is determined using dense box particle sampling and sequential purging. The carrier phase trajectory fully captures the dynamics of the UAS motion and enables precise relative position holding from t = 0 on. The proposed set membership filter scheme is fully complementary to and independent of any other algorithm employed to estimate the relative position. simulation results of the problem of cooperative relative localization between UAS on a formation flight benchmark compared to a standard Extended Kalman Filter illustrate the benefits arising from the deterministic nature of set membership filtering.
HESSER J. E.,STETSON P. B.,HARRISM W. E.,BOLTE M.,SMECKER-HANE T. A.,VANDENBERG D. A.,BELL R. A.,BOND H. E.,BERGH S. VAN DEN,MCCLURE R. D.,FAHLMAN G. G.,RICHER H. B. The Korean Astronomical Society 1996 Journal of The Korean Astronomical Society Vol.29 No.suppl1
We review observational evidence bearing on the formation of a prototypical large spiral galaxy, the Milky Way. New ground- and space-based studies of globular star clusters and dwarf spheroidal galaxies provide a wealth of information to constrain theories of galaxy formation. It appears likely that the Milky Way formed by an combination of rapid, dissipative collapse and mergers, but the relative contributions of these two mechanisms remain controversial. New evidence, however, indicates that initial star and star cluster formation occurred simultaneously over a volume that presently extends to twice the distance of the Magellanic Clouds.
Photoinduced degradation of 2,4-dichlorophenol in water: influence of various Fe(III) carboxylates
Wang, Lei,Zhang, Changbo,Mestankova, Hana,Wu, Feng,Deng, Nansheng,Pan, Gang,Bolte, Michele,Mailhot, Gilles Korean Society of Photoscience 2009 Photochemical & photobiological sciences Vol.8 No.7
Fe(III)-carboxylate complexes were investigated with respect to tri-carboxylic (citric), di-carboxylic (tartaric) and mono-carboxylic (pyruvic) acids. In agreement with the chemical structure, results demonstrated that Fe(III) was complexed by citric acid with a ratio of 1 : 1 (Fe/ligand), tartaric acid (D or L) with a ratio of 1 : 2 and by pyruvic acid with a ratio of 1 : 3. The iron concentration was fixed at 0.3 mmol $L^{-1}$ and the ligand concentration ranged from 0 to 1.0 mmol $L^{-1}$. The primary stage of 2,4-dichlorophenol (2,4-DCP) degradation photoinduced by these Fe(III) complexes was investigated under monochromatic irradiation (${\lambda}$ = 365, 313 and 296 nm). The values of initial quantum yields of 2,4-DCP disappearance (between 0.01 and 0.135) and Fe(II) formation (between 0.002 and 0.47) were evaluated and are presented in detail. Short irradiation wavelength (296 nm), low pH (3.0) and high oxygen concentration favoured the pollutant degradation. The disappearance of 2,4-DCP was complete under these favourable conditions.
Molecular insights into DNA interference by CRISPR-associated nuclease-helicase Cas3
Gong, Bei,Shin, Minsang,Sun, Jiali,Jung, Che-Hun,Bolt, Edward L.,van der Oost, John,Kim, Jeong-Sun National Academy of Sciences 2014 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.111 No.46
<P><B>Significance</B></P><P>Bacteria can repel invader DNA and RNA molecules by using an adaptive immunity mechanism called clustered regularly interspaced short palindromic repeats (CRISPRs)-Cas. CRISPR loci in a host genome are a repository of DNA fragments obtained from previous encounters with an invader, which can be transcribed and activated into short RNA molecules (crRNA) with sequences complementary to invader DNA or RNA. In some CRISPR-Cas systems, crRNA is assembled into a targeting complex called “Cascade” that seeks invader DNA to form an R-loop that triggers recruitment of a nuclease-helicase, Cas3, to destroy invader DNA. In this study, we show atomic resolution structures of a full-length Cas3, revealing how Cas3 coordinates binding, ATP-dependent translocation, and nuclease digestion of invader DNA.</P><P>Mobile genetic elements in bacteria are neutralized by a system based on clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (Cas) proteins. Type I CRISPR-Cas systems use a “Cascade” ribonucleoprotein complex to guide RNA specifically to complementary sequence in invader double-stranded DNA (dsDNA), a process called “interference.” After target recognition by Cascade, formation of an R-loop triggers recruitment of a Cas3 nuclease-helicase, completing the interference process by destroying the invader dsDNA. To elucidate the molecular mechanism of CRISPR interference, we analyzed crystal structures of Cas3 from the bacterium <I>Thermobaculum terrenum</I>, with and without a bound ATP analog. The structures reveal a histidine-aspartate (HD)-type nuclease domain fused to superfamily-2 (SF2) helicase domains and a distinct C-terminal domain. Binding of ATP analog at the interface of the SF2 helicase RecA-like domains rearranges a motif V with implications for the enzyme mechanism. The HD-nucleolytic site contains two metal ions that are positioned at the end of a proposed nucleic acid-binding tunnel running through the SF2 helicase structure. This structural alignment suggests a mechanism for 3′ to 5′ nucleolytic processing of the displaced strand of invader DNA that is coordinated with ATP-dependent 3′ to 5′ translocation of Cas3 along DNA. In agreement with biochemical studies, the presented Cas3 structures reveal important mechanistic details on the neutralization of genetic invaders by type I CRISPR-Cas systems.</P>