The description of chemical reactions by the method of the Full Optimized Reaction Space. The ring-opening of unsubstituted and substituted cyclopropylidene to allene

The ring-opening reaction of singlet cyclopropylidene to singlet D(,2d) allene is studied by means of ab-initio FORS-MCSCF calcula- tions. The energy surface is determined for many intermediate geometries defined by the C-C-C opening angle and the two CH(,2) rotation angles. For each choice of these three variables, the remaining twelve internal coordinates are relaxed by energy minimization. The results obtained differ markedly from those of earlier, less sophisticated calculations. As the C-C-C angle opens, the reaction is found to proceed first on a disrotatory pathway uphill to the transition region around a C-C-C angle of 84(DEGREES), where the reaction path bifurcates. It then follows one of two more or less conrotatory downhill pathways. From an opening angle of about 100(DEGREES) on there exists a state of free synchronized disrotatory motion in the molecule. It is shown that the reaction of the unsubstituted species is non-stereospecific;The characteristics of the bifurcating transition region, the first one ever found for a chemical reaction, are examined in detail and the theory governing similar surfaces is developed and generalized. It is shown that for a surface to exhibit such a bifurcation, a Valley Ridge Inflection (VRI) point must be present, i.e. the reaction path valley must, at some point, change into a ridge. Several examples of such surfaces are given and the actual reaction surface is fitted to the appropriate model by means of an analytical least mean squares fit;The geometries are first calculated using a minimal basis set. Based on these geometries, extended basis set calculations (including polarization functions) are performed for key points along the reaction path. The main effect of this basis set improve- ment is a substantive lowering of the ring-opening barrier;Since experimental evidence, based exclusively on the substi- tuted species, suggests that the reaction is stereospecific, a potential simulating the steric effects of substituents is added to the originally calculated surface. The results are analyzed and it is shown that all;experimental observations can be adequately explained solely by means of nonbonded interactions between substituent groups; *USDOE Report IS-T 1212. This work was performed under Contract No. W-7405-eng-82 with the U.S. Department of Energy

Decision shaping and strategy learning in multi-robot interactions

Recent developments in robot technology have contributed to the advancement of autonomous behaviours in human-robot systems; for example, in following instructions received from an interacting human partner. Nevertheless, increasingly many systems are moving towards more seamless forms of interaction, where factors such as implicit trust and persuasion between humans and robots are brought to the fore. In this context, the problem of attaining, through suitable computational models and algorithms, more complex strategic behaviours that can influence human decisions and actions during an interaction, remains largely open. To address this issue, this thesis introduces the problem of decision shaping in strategic interactions between humans and robots, where a robot seeks to lead, without however forcing, an interacting human partner to a particular state. Our approach to this problem is based on a combination of statistical modeling and synthesis of demonstrated behaviours, which enables robots to efficiently adapt to novel interacting agents. We primarily focus on interactions between autonomous and teleoperated (i.e. human-controlled) NAO humanoid robots, using the adversarial soccer penalty shooting game as an illustrative example. We begin by describing the various challenges that a robot operating in such complex interactive environments is likely to face. Then, we introduce a procedure through which composable strategy templates can be learned from provided human demonstrations of interactive behaviours. We subsequently present our primary contribution to the shaping problem, a Bayesian learning framework that empirically models and predicts the responses of an interacting agent, and computes action strategies that are likely to influence that agent towards a desired goal. We then address the related issue of factors affecting human decisions in these interactive strategic environments, such as the availability of perceptual information for the human operator. Finally, we describe an information processing algorithm, based on the Orient motion capture platform, which serves to facilitate direct (as opposed to teleoperation-mediated) strategic interactions between humans and robots. Our experiments introduce and evaluate a wide range of novel autonomous behaviours, where robots are shown to (learn to) influence a variety of interacting agents, ranging from other simple autonomous agents, to robots controlled by experienced human subjects. These results demonstrate the benefits of strategic reasoning in human-robot interaction, and constitute an important step towards realistic, practical applications, where robots are expected to be not just passive agents, but active, influencing participants

User experience evaluation of human representation in collaborative virtual environments

Human embodiment/representation in virtual environments (VEs) similarly to the human body in real life is endowed with multimodal input/output capabilities that convey multiform messages enabling communication, interaction and collaboration in VEs. This paper assesses how effectively different types of virtual human (VH) artefacts enable smooth communication and interaction in VEs. With special focus on the REal and Virtual Engagement In Realistic Immersive Environments (REVERIE) multi-modal immersive system prototype, a research project funded by the European Commission Seventh Framework Programme (FP7/2007-2013), the paper evaluates the effectiveness of REVERIE VH representation on the foregoing issues based on two specifically designed use cases and through the lens of a set of design guidelines generated by previous extensive empirical user-centred research. The impact of REVERIE VH representations on the quality of user experience (UX) is evaluated through field trials. The output of the current study proposes directions for improving human representation in collaborative virtual environments (CVEs) as an extrapolation of lessons learned by the evaluation of REVERIE VH representation

The description of chemical reactions by the method of the Full Optimized Reaction Space. The ring-opening of unsubstituted and substituted cyclopropylidene to allene

The ring-opening reaction of singlet cyclopropylidene to singlet D(,2d) allene is studied by means of ab-initio FORS-MCSCF calcula- tions. The energy surface is determined for many intermediate geometries defined by the C-C-C opening angle and the two CH(,2) rotation angles. For each choice of these three variables, the remaining twelve internal coordinates are relaxed by energy minimization. The results obtained differ markedly from those of earlier, less sophisticated calculations. As the C-C-C angle opens, the reaction is found to proceed first on a disrotatory pathway uphill to the transition region around a C-C-C angle of 84(DEGREES), where the reaction path bifurcates. It then follows one of two more or less conrotatory downhill pathways. From an opening angle of about 100(DEGREES) on there exists a state of free synchronized disrotatory motion in the molecule. It is shown that the reaction of the unsubstituted species is non-stereospecific;The characteristics of the bifurcating transition region, the first one ever found for a chemical reaction, are examined in detail and the theory governing similar surfaces is developed and generalized. It is shown that for a surface to exhibit such a bifurcation, a Valley Ridge Inflection (VRI) point must be present, i.e. the reaction path valley must, at some point, change into a ridge. Several examples of such surfaces are given and the actual reaction surface is fitted to the appropriate model by means of an analytical least mean squares fit;The geometries are first calculated using a minimal basis set. Based on these geometries, extended basis set calculations (including polarization functions) are performed for key points along the reaction path. The main effect of this basis set improve- ment is a substantive lowering of the ring-opening barrier;Since experimental evidence, based exclusively on the substi- tuted species, suggests that the reaction is stereospecific, a potential simulating the steric effects of substituents is added to the originally calculated surface. The results are analyzed and it is shown that all;experimental observations can be adequately explained solely by means of nonbonded interactions between substituent groups; *USDOE Report IS-T 1212. This work was performed under Contract No. W-7405-eng-82 with the U.S. Department of Energy.</p

The (H2o)2-Star Cluster at a Geometry of Intramolecular Charge-Transfer

Journal URL: http://www.sciencedirect.com/science/journal/0166128

Hydrogen Complexes of Be2(2+)

Journal URL: http://www.sciencedirect.com/science/journal/0009261