Gradually intractable problems and nondeterministic log-space lower bounds

The paper places five different problems (thek-pebble game problem, two problems aboutk finite automata, the reachability problem for Petri nets withk tokens, and the teachability problem for graphs whose k-dimensional edge sets are described by Cartesian products ofk factors) into the hierarchyNL _k of problems solvable by nondeterministic Turing machines ink-log₂ n space (and binary tape alphabet, to avoid tape speed-up). The results, when combined with the conjecture thatNL _i contains problems that requireO(n ^k ) deterministic time, show that these problems, while inP for every fixed value ofk, have polynomial deterministic time complexities with the degree of the polynomial growing linearly with the parameterk, and hence are, in this sense, gradually intractable.     

A self-organization learning algorithm for visuo-motor coordination in unstructured environments

In this paper, we propose a learning algorithm for coordinating a robot system where the movement of an arm is controlled through a stereo camera system. Instead of calibrating the usually complex non-linear transformation between the arm and cameras, the algorithm decomposes the whole transformation automatically into local linear transformations and then makes the linearization map recorded by the arm controller. The linearization is carried out by a learning process based on a Kohonen-style self-organization network. To deal with unstructured environments in which some obstacles exist, some virtual forces are introduced for dealing with the high degree of complexity underlying in the transformation. This work was presented, in part, at the International Symposium on Artificial Life and Robotics, Oita, Japan, February 18–20, 1996     

Investigation of high-temperature chemical interaction of calcium silicate insulation and cesium hydroxide

ABSTRACT

The interaction of cesium hydroxide and a calcium silicate insulation material was experimentally investigated at high-temperature conditions to evaluate the possibility of unprecedented cesium retention under severe accident of boiling water reactor. The temperature where the interactions occurred and chemical species of cesium after the interaction were examined in this study. A thermogravimetry equipped with differential thermal analysis was used to analyze thermal events in the samples of mixed calcium silicate and cesium hydroxide under oxidizing and reducing atmospheric conditions with a maximum temperature of 1100°C. Before being mixed with cesium hydroxide, a part of calcium silicate was pretreated at high temperature to evaluate the effect of possible structural changes of this material due to a preceding thermal history and also for the sake of thermodynamic evaluation. It was found that for the original material, as xonotlite (Ca₆Si₆O₁₇(OH)₂) crystal, the endothermic reaction with cesium hydroxide occurred over the temperature range 575–730°C; meanwhile, for heat-treated material, which varied the crystal phase of original material to wollastonite (CaSiO₃), the interaction occurred over the temperature range 700–1100°C. The X-ray diffraction analyses have indicated that both types of calcium silicates regardless of the atmospheric conditions, cesium aluminum silicate, CsAlSiO₄, was formed with aluminum in the samples as an impurity or adduct. The insolubility of this formed cesium suggested the potency of cesium localization in the primary containment vessels on other structural materials that possess similar elements to that of calcium silicate insulation; hence, an effective decommissioning process could be developed.     

Fluctuation of Global Gene Expression by Endogenous miRNA Response to the Introduction of an Exogenous miRNA

Most of the intracellular endogenous microRNAs (endo-miRNAs) are considered to be saturated in Argonaute (Ago) proteins in the RNA-induced silencing complexes (RISCs). When exogenous miRNAs (exo-miRNAs) are introduced into cells, endo-miRNAs in the RISC may be replaced with exo-miRNAs or exo-miRNAs, and endo-miRNAs might also compete for the position in the newly synthesized RISC with each other. This would lead to the fluctuation of global gene expression not only by repression of exo-miRNA target gene expression, but also by the increase of the endo-miRNA target gene expression. In the present study, we quantified the changes in the expression levels of target genes of exo-miRNA and endo-miRNA in the cells transfected with fifteen different exo-miRNAs by microarray experiments. Different exo-miRNAs increased ratios of expression levels of target genes of a given endo-miRNA to different extents, suggesting that the replacement efficiencies might differ according to the exo-miRNA types. However, the increased ratios in the expression levels of each endo-miRNA target genes by the transfection of any particular exo-miRNA were mostly equivalent, suggesting that the endo-miRNAs present in the RISC might be replaced with excessive exo-miRNAs at similar levels, probably because they exist in single-stranded forms in the RISC.     

Performance of surface ionic conduction single chamber fuel cell prepared by the sol gel method

The performance of surface ionic conduction single chamber fuel cell (SIC‐SCFC) prepared by the sol gel method was studied on electric characteristics due to the differences of the operating temperature and humidity, the electrode distance and electrolyte film depth, and multiple cells with the series and parallel connections. The SIC–SCFC was arranged the both anode of Pt and cathode of Au on the boehmite electrolyte. The open circuit voltage (OCV) of single cell achieved a maximum of 530mV in the dry gas mixtures of O₂/H₂=50% in room temperature operation, and but it became decrease as over 60%. The OCV was maintained the constant value between operating temperatures of 30°C to 80°C, and but it was decreased sharply at over 90°C because a humidity on the cell became lower as increasing operating temperature. Then, the cell property was improved to 120°C by adding to the humidity of 70% using a humidifier. The electrode distance and the electrolyte film depth of SIC‐SCFC found to be contributed to the reductions of the cell resistance and the surface roughness on the electrode, respectively. Moreover, the power property of SIC‐SCFC was significantly improved by cell stacks comprised of the series or parallel connection of a cell.     

A multiagent‐based microgrid operation method considering charging and discharging strategies of electric vehicles

In this paper, we propose a multiagent‐based microgrid (MG) operation method considering charging and discharging electric vehicles (EVs). The proposed system consists of five types of agents: single microgrid controller agent, several load agents, several gas turbines/engine agents, several photovoltaic generation agents, and several electric vehicle agents. In the proposed method, the load balancing can be realized by suppressing sudden fluctuations in supply and demand balance due to the synchronization of charging and discharging of EVs. From the simulation results, it can be seen that the proposed multiagent system could realize the load equalization in MG.     

A PSS‐Free PEDOT Conductive Film Supported by a Hierarchical Nanoporous Layer Glass

The importance of transparent conductive film is increasing due to its use in applications such as touch‐panel devices. Although indium tin oxide is widely used because of its high conductivity and transparency, conductive polymers are being studied as alternative materials that avoid the use of rare metals and the brittleness associated with existing systems. Polyethylene dioxythiophene (PEDOT)/polyethylene sulfonic acid (PSS) is drawing a lot of attention due to its well‐balanced conductivity, transparency, film formability, and chemical stability. The nonconductive PSS reportedly covers the conductive PEDOT. The PSS shell provides carrier and film‐formability to PEDOT but is also a barrier that hinders electrical conductivity. Therefore, the PEDOT film formability is explored supported by a substrate without the addition of PSS. The “hierarchical nanoporous layer glass” holds the PSS‐free PEDOT with its nanopores to form a homogeneous, transparent film. The PSS‐free PEDOT film thus achieves transparency of over 85% and resistivity of below 500 Ω sq^?1.     

Low‐power‐consumption TFT‐LCD with dynamic memory embedded in the pixels

A low‐power‐consumption thin‐film‐transistor liquid‐crystal display (TFT‐LCD) with dynamic memory cells embedded in each pixel using low‐temperature poly‐Si technology has been developed. By holding data in the memory, the operating rate of the data driver can be dramatically reduced to 4 Hz. Eight levels of gray scale with low power consumption can be achieved by using the area‐ratio gray‐scale method. This TFT‐LCD can be used for displaying fine still images, with low power consumption.     

SleepExplorer: a visualization tool to make sense of correlations between personal sleep data and contextual factors

Getting enough quality sleep is a key part of a healthy lifestyle. Many people are tracking their sleep through mobile and wearable technology, together with contextual information that may influence sleep quality, like exercise, diet, and stress. However, there is limited support to help people make sense of this wealth of data, i.e., to explore the relationship between sleep data and contextual data. We strive to bridge this gap between sleep-tracking and sense-making through the design of SleepExplorer, a web-based tool that helps individuals understand sleep quality through multi-dimensional sleep structure and explore correlations between sleep data and contextual information. Based on a two-week field study with 12 participants, this paper offers a rich understanding on how technology can support sense-making on personal sleep data: SleepExplorer organizes a flux of sleep data into sleep structure, guides sleep-tracking activities, highlights connections between sleep and contributing factors, and supports individuals in taking actions. We discuss challenges and opportunities to inform the work of researchers and designers creating data-driven health and well-being applications.