Multi-agent Motion Planning for Dense and Dynamic Environments via Deep Reinforcement Learning

This paper introduces a hybrid algorithm of deep reinforcement learning (RL) and Force-based motion planning (FMP) to solve distributed motion planning problem in dense and dynamic environments. Individually, RL and FMP algorithms each have their own limitations. FMP is not able to produce time-optimal paths and existing RL solutions are not able to produce collision-free paths in dense environments. Therefore, we first tried improving the performance of recent RL approaches by introducing a new reward function that not only eliminates the requirement of a pre supervised learning (SL) step but also decreases the chance of collision in crowded environments. That improved things, but there were still a lot of failure cases. So, we developed a hybrid approach to leverage the simpler FMP approach in stuck, simple and high-risk cases, and continue using RL for normal cases in which FMP can't produce optimal path. Also, we extend GA3C-CADRL algorithm to 3D environment. Simulation results show that the proposed algorithm outperforms both deep RL and FMP algorithms and produces up to 50% more successful scenarios than deep RL and up to 75% less extra time to reach goal than FMP.Comment: IEEE Robotics and Automation Letters (2020

The Ithaca Interpretation of Quantum Mechanics

I list several strong requirements for what I would consider a sensible interpretation of quantum mechanics and I discuss two simple theorems. One, as far as I know, is new; the other was only noted a few years ago. Both have important implications for such a sensible interpretation. My talk will not clear everything up; indeed, you may conclude that it has not cleared anything up. But I hope it will provide a different perspective from which to view some old and vexing puzzles (or, if you believe nothing needs to be cleared up, some ancient verities.)Comment: 21 pages, plain TEX. Notes for a lecture given at the Golden Jubilee Workshop on Foundations of Quantum Theory, Tata Institute, Bombay, September 9-12, 199

Feynman's interpretation of quantum theory

A historically important but little known debate regarding the necessity and meaning of macroscopic superpositions, in particular those containing different gravitational fields, is discussed from a modern perspective.Comment: Published version for Eur.Phys.J. H. 15 pages pdf. Final version available at http://www.springerlink.com/openurl.asp?genre=article&id=doi:10.1140/epjh/e2011-10035-

Detection of Planetary and Stellar Companions to Neighboring Stars via a Combination of Radial Velocity and Direct Imaging Techniques

13 pages, 6 figures, 4 tables, accepted for publication in the Astronomical Journal (submitted 25 Feb 2019; accepted 28 April 2019). Machine readable tables and Posteriors from the RadVel fits are available here: http://stephenkane.net/rvfits.tarThe sensitivities of radial velocity (RV) surveys for exoplanet detection are extending to increasingly longer orbital periods, where companions with periods of several years are now being regularly discovered. Companions with orbital periods that exceed the duration of the survey manifest in the data as an incomplete orbit or linear trend, a feature that can either present as the sole detectable companion to the host star, or as an additional signal overlain on the signatures of previously discovered companion(s). A diagnostic that can confirm or constrain scenarios in which the trend is caused by an unseen stellar rather than planetary companion is the use of high-contrast imaging observations. Here, we present RV data from the Anglo-Australian Planet Search (AAPS) for 20 stars that show evidence of orbiting companions. Of these, six companions have resolved orbits, with three that lie in the planetary regime. Two of these (HD 92987b and HD 221420b) are new discoveries. Follow-up observations using the Differential Speckle Survey Instrument (DSSI) on the Gemini South telescope revealed that 5 of the 20 monitored companions are likely stellar in nature. We use the sensitivity of the AAPS and DSSI data to place constraints on the mass of the companions for the remaining systems. Our analysis shows that a planetary-mass companion provides the most likely self-consistent explanation of the data for many of the remaining systems.Peer reviewedFinal Accepted Versio

Removal of Multiway Stop Signs with Minimum Hazard, Volume I: Technical Report

DTFH61-82-C-00029This study reports on the experience of more than 30 political jurisdictions throughout the United States which have converted multiway, stop sign-controlled intersections to lesser forms of controls. In all instances, those officials interviewed during field visits reported converting 4-way or 3-way stop intersections to 2-way or 1-way stop intersections. A great variety of procedures and accompanying notice, caution, and warning signs were found to have been used in the conversion of the more than 172 intersections studied. Generally, low volume, low speed, residential intersections were being converted safely without the use of supplementary signs. As intersection volumes increased, there was an increased need for multiway stop sign-intersection conversion aids. Procedures were developed by which multiway stop sign-controlled intersection can be converted to lesser forms of control with minimum hazard. Signs installed prior to the conversion. Signs placed under the remaining stop signs after conversion should read "CAUTION, CROSS TRAFFIC DOES NOT STOP." Any stop line pavement markings on the new through street should be removed. Volume I reports on the overall study effort. Volume II addresses details of the recommended conversion procedures for use as a guide by local officials

Forecast for Military Systems Using Electronic Digital Computers

Many plans are now being considered for the military use of information systems built around electronic digital computers. Such systems appear unique in their ability to process and evaluate information sufficiently rapidly for modern high-speed military operations. The advantages gained when digital information systems make possible the better integration and more effective use of other military equipment should more than justify the diversion of men and resources to digital information system development. An approximate estimate has been made of the time and cost to bring such information systems to useful military realization. This forecast shows a period of fifteen years and a research and development cost, including field testing and trial operation, of two billion dollars ($2,000,000,000) to bring these systems to an operational status. An equal or greater production program would follow for equipping the Military Services with production equipment. Compensating adjustments in completion time and total cost can be made to meet military necessity. Such a program would require an active training plan to provide necessary personnel. An initial investigation requiring four years and sixty-five million dollars ($65,000,000) would provide tho necessary information on which the importance and feasibility of the complete program could be judged

Climate emergency summit III:nature-based solutions report

An RSGS & SNH report from the Climate Summit held in April 2020"The Climate Emergency is the result of burning fossils fuels and changes in the way we use the land that short-circuit global carbon and nitrogen cycles. To remain within safe climate limits (1.5-2°C), the remaining carbon budget for all people, and for all time, is now so small that stopping fossil fuel use, while essential, will not by itself address the problem. Changing the way we use the land and sea is now essential. Nature-based solutions are vital to creating a safe operating space for humanity. "Extract from the foreword by Dr Clive Mitchell, Outcome Manager: People and Nature, Scottish Natural Heritage. The report has 45 contributors for a variety of institutions

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