Multi-contact vertical ladder climbing with an HRP-2 humanoid

We describe the research and the integration methods we developed to make the HRP-2 humanoid robot climb vertical industrial-norm ladders. We use our multi-contact planner and multi-objective closed-loop control formulated as a QP (quadratic program). First, a set of contacts to climb the ladder is planned off-line (automatically or by the user). These contacts are provided as an input for a finite state machine. The latter builds supplementary tasks that account for geometric uncertainties and specific grasps procedures to be added to the QP controller. The latter provides instant desired states in terms of joint accelerations and contact forces to be tracked by the embedded low-level motor controllers. Our trials revealed that hardware changes are necessary, and parts of software must be made more robust. Yet, we confirmed that HRP-2 has the kinematic and power capabilities to climb real industrial ladders, such as those found in nuclear power plants and large scale manufacturing factories (e.g. aircraft, shipyard) and construction sites.     

Is numerical comparison digital? Analogical and symbolic effects in two-digit number comparison.

Do Ss compare multidigit numbers digit by digit (symbolic model) or do they compute the whole magnitude of the numbers before comparing them (holistic model)? In 4 experiments of timed 2-digit number comparisons with a fixed standard, the findings of J. V. Hinrichs et al (see record 1982-07073-001) were extended with French Ss. Reaction times (RTs) decreased with target-standard distance, with discontinuities at the boundaries of the standard's decade appearing only with standards 55 and 66 but not with 65. The data are compatible with the holistic model. A symbolic interference model that posits the simultaneous comparison of decades and units can also account for the results. To separate the 2 models, the decades and units digits of target numbers were presented asynchronously in Experiment 4. Contrary to the prediction of the interference model, presenting the units before the decades did not change the influence of units on RTs. Pros and cons of the holistic model are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of flow characteristics on the diffusion-limited current density in an electrodeposition cell

The main parameters characterizing the effect of the turbulent flow of an electrolyte between two planar electrodes, one of which may be in motion, are demonstrated by means of numerical and experimental studies. The analysis is carried out for the case of zinc electrodeposition. A model is proposed, which takes into account the production of hydrogen, to represent the variation of the diffusion limited current density as a function of the flow characteristics and of the solution composition.     

Application of the SIMS Method in Studies of Cr Segregation in Cr-Doped CoO: I, Aspects of Quantitative Analysis

Aspects of calibration of intensities of SIMS secondary ions vs concentration as well as sputtering time vs depth are considered for Cr-doped CoO. Advantages and limitations of the SIMS method in quantitative analysis of segregation-induced concentration profiles in oxide crystals are discussed. The studies indicate a substantial effect due to charging the surface during sputtering. The depth calibration was performed by using the Ta₂O₅/Ta system as a standard. Good depth resolution was revealed. The calibration dependence of Cr intensities on concentration is characterized by a wide scatter of data caused by charging the surface. Very good shape reproducibility of the intensity ratio vs depth profiles was revealed. Therefore, normalized intensity ratios can be used for calibration.     

Mössbauer resonance studies on the Ca2Fe2O5-LaFeO3 system

Phases between Ca₂Fe₂O₅ and LaFeO₃ with La_1?2yCa_2yFe³⁺O_3?y formulation have been prepared in order to study the oxygen defects in perovskite-related ferrites. X-ray-diffraction analysis and magnetic measurements have confirmed the previous results i.e. the existence of a critical concentration of vacancies above which long range ordering appears. A detailed Mössbauer resonance study shows a continuous evolution of the iron environment, tetrahedra being formed even for low values of y. This result has been discussed and compared with previous ones for homologous CaTi_1?2yFe_2yO_?y phases.     

Electrochemical impedance spectroscopy of BaCeO3 modified by Ti and Y

Barium cerate exhibits high protonic conductivity, especially when modified by trivalent dopant such as Y, Yb, Nd, Sm or Dy. Unfortunately, the poor chemical stability in the presence of CO₂ is the main disadvantage of this material. One of the possible approach to get the stable protonic conductor is the preparation of solid solutions. For example, doping of BaCeO₃ with Zr leads to the improvement of the chemical stability, but the electrical properties are simultaneously corrupted.In the present work the influence of Ti, per analogy to Zr, and Y dopants on electrical properties of BaCeO₃ was investigated using the electrochemical impedance spectroscopy (EIS) technique. BaCe_1−xTi_xO_3−δ (0 ≤ x ≤ 0.3) and Ba(Ce_0.95Ti_0.05)_0.95Y_0.05O_3−δ solid electrolytes were prepared by solid-state reaction method. It was found that the changes of electrical properties due to the introduction of Ti into the BaCeO₃ lattice is caused predominantly by the modification of the grain boundary properties. The Ti doping leads to the substantial decrease of grain boundary electrical conductivity, comparing to undoped material. The introduction of yttrium dopant to the BaCe_0.95Ti_0.05O₃ lattice has the opposite effect. The total electrical conductivity increases, due to significant modification of grain boundary electrical properties.     

Screening Approach for the Discovery of New Hybrid Perovskites with Efficient Photoemission

Owing to quantum confinement, low‐dimensional hybrid perovskite materials have recently shown a great potential for applications in optoelectronics. Such compounds can exhibit broad‐ or narrow‐band light emission, low‐temperature solution processability, high thermal stability, and relatively high photoluminescence quantum yields (PLQY). However, the search for efficient phosphors with a specific set of characteristics remains difficult because the family of hybrid perovskites consists in an extremely large chemical system (i.e., different halides, metals, and organic molecules), and optical properties are not predictable prior to material synthesis and characterization. Here, is proposed a simple approach to screen a significant amount of new hybrid lead halide perovskites. The synthetic method by fast crystallization at low temperature enables the rapid identification of the materials exhibiting the targeted photoluminescence properties. This approach is tested for the discovery of hybrid lead halide perovskites with efficient white‐light emission. Among 100 newly synthesized compounds, 5 exhibit intense white emission, and the in‐depth characterization of a selected candidate shows high color rendering index (CRI) = 78 and a PLQY of 9%, which is equivalent to the record reported for hybrid perovskites. This compound exhibits a new structure type for warm white‐light emitting hybrid perovskites with chains of corner‐sharing PbX₆.     

The coatings and high temperature corrosion data bank

This paper presents the current structure of C&HTC-DATA, the data bank on coatings and high temperature corrosion which has been created and is going to be operated by the Corrosion Data Center at the University of Provence in Marseilles, France. This data bank includes five databases, namely a bibliographic database, a coating database, a substrate alloy database, a corrosion database and a directory of research institutes and companies involved in high temperature corrosion and protection. These databases have been installed by a relational database management system. Computerized data collection forms have been perfected and tested and are used to collect data for the databases. The implementation with the data activity scheme of building the data bank, the metadata on coating and corrosion, the structure of the data bank and the structure of the databases composing the data bank are presented.