Robert A. Singer

The majority of tactical weapons systems require that manned maneuverable vehicles, such as aircraft, ships, and submarines, be tracked accurately. An optimal Kalman filter has been derived for this purpose using a target model that is simple to implement and that represents closely the motions of maneuvering targets. Using this filter, parametric tracking accuracy data have been generated as a function of target maneuver characteristics, sensor observation noise, and data rate and that permits rapid a priori estimates of tracking performance to be made when maneuvering targets are to be tracked by sensors providing any combination of range, bearing, and elevation measurements.

Mixtures of palladium acetate and o-(di-tert-butylphosphino)biphenyl (4) catalyze the room-temperature Suzuki coupling of aryl bromides and aryl chlorides with 0.5−1.0 mol % Pd. Use of o-(dicyclohexylphosphino)biphenyl (2) allows Suzuki couplings to be carried out at low catalyst loadings (0.000001−0.02 mol % Pd). The process tolerates a broad range of functional groups and substrate combinations including the use of sterically hindered substrates. This is the most active catalyst system in terms of reaction temperature, turnover number, and steric tolerance which has been reported to date.

Asymmetric catalysis of the Mukaiyama aldol reaction has been reported with complexes derived from Al, B, Sn(II), and
\nTi(IV). The levels of asymmetric induction for the addition of propionate-, isobutyrate-, and acetate-derived silyl thioketene acetals to aldehydes parallel those obtained with chiral-auxiliary-based methodologies. However, silyl ketene acetals derived from O-alkyl acetates uniformly provide aldolates possessing lower levels of asymmetric induction. We have initiated a study aimed at the design and synthesis of chiral Ti(IV) complexes that catalyze the enantioselective Mukaiyama aldol of O-trimethylsilyl, O-methyl, and O-ethyl ketene acetals with aldehydes. We report herein a catalyst that consists of a tridentate ligand derived from 3, Ti(O'^iPr)_4, and 3,5-di-tert-butylsalicylic acid. This catalyst (2-5 mol %) furnishes aldol adducts in good yields and high levels of asymmetric induction (88-97% ee).

When tracking targets in dense environments, sensor reports originating from sources other than the target being tracked (i.e., from clutter, thermal false alarms, other targets) are occasionally incorrectly used in track updating. As a result tracking performance degrades, and the error covariance matrix calculated on-line by the usual types of tracking filters becomes extremely unreliable for estimating actual accuracies. This paper makes three contributions in this area. First, a new tracking filter is developed that incorporates, in an a posteriori statistical fashion, all data available from sensor reports located in the vicinity of the track, and that provides both optimal performance and reliable estimates of this performance when operating in dense environments. The optimality of and the performance equations for this filter are verified by analytical and simulation results. Second, several computationally efficient classes of suboptimal tracking filters based on the optimal filter developed in this paper and on an optimal filter of another class that appeared previously in the literature are developed. Third, using an extensive Monte Carlo simulation, the various optimal and suboptimal filters as well as the Kalman filter are compared, with regard to the differences between the on-line calculated and experimental covariances of each filter, and with regard to relative accuracies, computational requirements, and numbers of divergences or lost tracks each produces.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCatalytic, Enantioselective Dienolate Additions to Aldehydes: Preparation of Optically Active Acetoacetate Aldol AdductsRobert A. Singer and Erick M. CarreiraCite this: J. Am. Chem. Soc. 1995, 117, 49, 12360–12361Publication Date (Print):December 1, 1995Publication History Published online1 May 2002Published inissue 1 December 1995https://pubs.acs.org/doi/10.1021/ja00154a049https://doi.org/10.1021/ja00154a049research-articleACS PublicationsRequest reuse permissionsArticle Views1984Altmetric-Citations217LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (2)»Supporting Information Supporting Information Get e-Alerts