Perceiving guaranteed collision-free robot trajectories in unknown and unpredictable environments

The dissertation introduces novel approaches for solving a fundamental problem: detecting a collision-free robot trajectory based on sensing in real-world environments that are mostly unknown and unpredictable, i.e., obstacle geometries and their motions are unknown. Such a collision-free trajectory must provide a guarantee of safe robot motion by accounting for robot motion uncertainty and obstacle motion uncertainty. Further, as simultaneous planning and execution of robot motion is required to navigate in such environments, the collision-free trajectory must be detected in real-time. Two novel concepts: (a) dynamic envelopes and (b) atomic obstacles, are introduced to perceive if a robot at a configuration q, at a future time t, i.e., at a point ? = (q, t) in the robot's configuration-time space (CT space), will be collision-free or not, based on sensor data generated at each sensing moment t, in real-time. A dynamic envelope detects a collision-free region in the CT space in spite of unknown motions of obstacles. Atomic obstacles are used to represent perceived unknown obstacles in the environment at each sensing moment. The robot motion uncertainty is modeled by considering that a robot actually moves in a certain tunnel of a desired trajectory in its CT space. An approach based on dynamic envelopes is presented for detecting if a continuous tunnel of trajectories are guaranteed collision-free in an unpredictable environment, where obstacle motions are unknown. An efficient collision-checker is also developed that can perform fast real-time collision detection between a dynamic envelope and a large number of atomic obstacles in an unknown environment. The effectiveness of these methods is tested for different robots using both simulations and real-world experiments

Electron, Muon, and Hadron Lateral Distributions Measured in Air-Showers by the KASCADE Experiment

Measurements of electron, muon, and hadron lateral distributions of extensive air showers as recorded by the KASCADE experiment are presented. The data cover the energy range from about 5x10^14 eV up to almost 10^17 eV and extend from the inner core region to distances of 200 m. The electron and muon distributions are corrected for mutual contaminations by taking into account the detector properties in the experiment. All distributions are well described by NKG-functions. The scale radii describing the electron and hadron data best are approx. 30 m and 10 m, respectively. We discuss the correlation between scale radii and `age' parameter as well as their dependence on shower size, zenith angle, and particle energy threshold.Comment: 28 pages, 14 figures, Accepted for publication in Astroparticle Physic

Observations on the nuclear interaction of cosmic ray pions and nucleons of energies ≳ 20 GeV. Part I. Experimental details and results relating to fluctuations in the angular distribution of the secondary particles produced in interactions in carbon

In this paper, which is the first of a series entitled 'Observations on the Nuclear Interactions of Cosmic Ray Pions and Nucleons of Energy ≳ 20 GeV', a description is given of the experimental arrangement, the types of data collected and the methods employed to analyse and classify the data. Results on the fluctuations in the angular distribution of the secondary particles produced in interactions in carbon are also presented and it is shown that these fluctuations are considerably larger in certain cases than what can be accounted for purely from statistical fluctuations in the isotropic and uncorrelated emission of secondaries in the c.m. system of the collision with a target nucleon and in others difficult to be understood on this basis if additional features of these interactions are also considered. It is suggested that 'correlated emission' of secondaries possibly due to final state inter-actions or multiparticle resonances with different 'Q-values' and other properties are perhaps the cause of the observed fluctuations; this is in contrast to the explanation in terms of simple motion of 'fire balls' in the c.m. system as has been generally discussed

Observations on the nuclear interactions of cosmic ray pions and nucleons at energies ≳ 20 GeV Part II. The extremely collimated nuclear interactions

Detailed features of extremely collimated nuclear interactions induced by cosmic ray particles in carbon and brass (belonging to group I as classified in Part I of this series of papers) are presented. These extremely collimated nuclear interactions seem to be preferentially induced by pions rather than by nucleons; also the relative frequency of these seems to be less when brass is used as target compared to the case with carbon as target. The distribution of multiplicities of secondary particles emitted in the forward direction show certain regularities in the case of interactions induced by charged primaries. Observations on the γ-rays associated with these events give support to the interpretation that in these inelastic collisions pions are produced in pairs in the forward direction with low transverse momentum. It is suggested that such a low energy di-pion system could be the same as found in the so-called ABC effect

Gas separation by membranes : technology and business assessment

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1985.Bibliography: leaves 123-132.by Sorab R. Vatcha.M.S

Charismatic Leadership and Corporate Cultism at Enron: The Elimination of Dissent, the Promotion of Conformity and Organizational Collapse

Enron stands out as one of the most spectacular failures in business history. Thus far, most attention has been focused on its accountancy practices. This article, by contrast, explores its internal culture and the leadership practices of its top people. These included a particular emphasis on charismatic leadership, particularly in the persons of Kenneth Lay and Jeffrey Skilling; the promotion of a compelling vision by these leaders of a totalistic nature; individual consideration, expressed in a recruitment system designed to activate a process analogous to conversion; and the promotion of a culture characterized by conformity and the penalizing of dissent. Drawing on the vast archive of material now available on Enron, and in particular on the best known accounts of former employees, the article discusses to what extent Enron can be usefully regarded as an example of a corporate cult. Finally, the discussion is located in the context of emerging trends in business and leadership practice, and considers the extent to which what happened at Enron is suggestive of a growing business phenomenon

Charismatic leadership and corporate cultism at Enron: the elimination of dissent, the promotion of conformity and organizational collapse

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Evidence for change in the characteristics of strong interactions at ultra-high energies

An attempt has been made to understand the experimental results on the size dependence of several properties of high energy hadrons reported in a previous paper (see ibid., vol.6, no.7, 1050 of 1973) in terms of the characteristics of high energy collisions and primary composition using detailed Monte Carlo simulations. It is shown that the behaviour of the high energy hadron component, especially the size dependence, cannot be accounted for in terms of a change of primary composition alone in the energy range 1014-1016 eV which has been suggested by some of the earlier investigations to explain certain properties of air showers. The present analysis strongly suggests the need for invoking rather drastic changes in the characteristics of strong interactions at ultra-high energies