Toyota

About: Toyota is a company organization based out in Safenwil, Switzerland. It is known for research contribution in the topics: Internal combustion engine & Battery (electricity). The organization has 40032 authors who have published 55003 publications receiving 735317 citations. The organization is also known as: Toyota Motor Corporation & Toyota Jidosha KK.

Online convex optimization in the bandit setting: gradient descent without a gradient

Abstract: We study a general online convex optimization problem. We have a convex set S and an unknown sequence of cost functions c1, c2,..., and in each period, we choose a feasible point xt in S, and learn the cost ct(xt). If the function ct is also revealed after each period then, as Zinkevich shows in [25], gradient descent can be used on these functions to get regret bounds of O(√n). That is, after n rounds, the total cost incurred will be O(√n) more than the cost of the best single feasible decision chosen with the benefit of hindsight, minx Σ ct(x).We extend this to the "bandit" setting, where, in each period, only the cost ct(xt) is revealed, and bound the expected regret as O(n3/4).Our approach uses a simple approximation of the gradient that is computed from evaluating ct at a single (random) point. We show that this biased estimate is sufficient to approximate gradient descent on the sequence of functions. In other words, it is possible to use gradient descent without seeing anything more than the value of the functions at a single point. The guarantees hold even in the most general case: online against an adaptive adversary.For the online linear optimization problem [15], algorithms with low regrets in the bandit setting have recently been given against oblivious [1] and adaptive adversaries [19]. In contrast to these algorithms, which distinguish between explicit explore and exploit periods, our algorithm can be interpreted as doing a small amount of exploration in each period.

Electronic and optical properties of anatase TiO 2

Abstract: First-principles calculations using the full-potential linearized augmented plane-wave method have been performed to investigate detailed electronic and optical properties of ${\mathrm{TiO}}_{2}$ in the anatase structure. The fully optimized structure, obtained by minimizing the total energy and atomic forces, are in good agreement with experiment. Stabilization of the structure by the trade off between a favorable coordination in the ${\mathrm{sp}}^{2}$ hybridization and the Coulomb repulsion among oxygen atoms is also demonstrated. We calculate band structure, densities of states and charge densities, and interpret their features in terms of the bonding structure in the molecular orbital picture. The optical properties, calculated within the dipole approximation, are found to agree with recent experiments on single crystals of anatase ${\mathrm{TiO}}_{2}.$ Near the absorption edge, the results show a significant optical anisotropy in the components parallel and perpendicular to the c axis. We demonstrate that this large dichroism results from the existence of nonbonding ${d}_{\mathrm{xy}}$ orbitals located at the bottom of the conduction bands, which allows direct dipole transitions dominantly for the perpendicular component.

Homogeneous catalytic hydrogenation of supercritical carbon dioxide

Abstract: THE use of carbon dioxide as a starting material for the synthesis of organic compounds has long been a goal for synthetic chemists. The hydogenation of carbon dioxide to formic acid, methanol and other organic substances is particularly attractive, but has remained difficult. This route to formic acid has been described recently, based on the use of organometallic rhodium catalysts in dimethyl sulphoxideII and aqueous2 solvents. We report here the efficient production of formic acid in a supercritical mixture of carbon dioxide and hydrogen containing a catalytic ruthenium() phosphine complex. The use of a supercritical phase, in which hydrogen is highly miscible, leads to a very high initial rate of reaction up to 1,400 moles of formic acid per mole of catalyst per hour. The same reaction under identical conditions but in liquid organic solvents is much slower. Our results suggest that supercritical fluids represent a promising medium for homogeneous catalysis.

Path Planning for Autonomous Vehicles in Unknown Semi-structured Environments

Abstract: We describe a practical path-planning algorithm for an autonomous vehicle operating in an unknown semi-structured (or unstructured) environment, where obstacles are detected online by the robot’s sensors. This work was motivated by and experimentally validated in the 2007 DARPA Urban Challenge, where robotic vehicles had to autonomously navigate parking lots. The core of our approach to path planning consists of two phases. The first phase uses a variant of A* search (applied to the 3D kinematic state space of the vehicle) to obtain a kinematically feasible trajectory. The second phase then improves the quality of the solution via numeric non-linear optimization, leading to a local (and frequently global) optimum. Further, we extend our algorithm to use prior topological knowledge of the environment to guide path planning, leading to faster search and final trajectories better suited to the structure of the environment. We present experimental results from the DARPA Urban Challenge, where our robot demonstrated near-flawless performance in complex general path-planning tasks such as navigating parking lots and executing U-turns on blocked roads. We also present results on autonomous navigation of real parking lots. In those latter tasks, which are significantly more complex than the ones in the DARPA Urban Challenge, the time of a full replanning cycle of our planner is in the range of 50—300 ms.

Electrolyte roadblocks to a magnesium rechargeable battery

Abstract: Low cost, non-dendritic magnesium metal is an ideal anode for a post lithium ion battery. Currently, development of magnesium electrolytes governs the rate of progress in this field, because electrolyte properties determine the class of cathodes utilized. A review of the latest progress in the area of magnesium battery electrolyte and a perspective on mitigating present challenges is presented herein. Firstly, density functional theory has been shown to predict the potential window of magnesium electrolytes on inert electrodes. Secondly, we report initial efforts aimed to overcome the corrosive property of these magnesium organohaloaluminates towards less noble metals such as stainless steel. This is a major challenge in developing high voltage magnesium electrolytes essential for batteries which operate above 3V. We lastly touch on cathode candidates including the insertion and conversion classes. One conversion cathode we pay particular attention to is electrophilic sulfur which can be married with magnesium metal anodes by utilizing non-nucleophilic electrolytes obtained by simple crystallization of in situ generated magnesium organohaloaluminates. Effectively, non-nucleophilic electrolytes open the door to research on magnesium/sulfur batteries.