An alternative approach to comprehensive Gröbner bases

AbstractWe give an alternative definition of comprehensive Gröbner bases in terms of Gröbner bases in polynomial rings over commutative Von Neumann regular rings. Our comprehensive Gröbner bases are defined as Gröbner bases in polynomial rings over certain commutative Von Neumann regular rings, hence they have two important properties which do not hold in standard comprehensive Gröbner bases. One is that they have canonical forms in a natural way. Another one is that we can define monomial reductions which are compatible with any instantiation. Our comprehensive Gröbner bases are wider than Weispfenning’s original comprehensive Gröbner bases. That is there exists a polynomial ideal generated by our comprehensive Gröbner basis which cannot be generated by any of Weispfenning’s original comprehensive Gröbner bases

Superfluidity of liquid 4He confined to one-dimensional straight nanochannel structures

Superfluidity of liquid 4He confined in one-dimensional (1D) nanometer-size channels has been studied by means of a torsional oscillator. When the channel is larger than 2.8 nm in diameter, liquid 4He becomes superfluid at low temperatures and a dissipation due to quantized vortex is observed. The superfluid onset temperature is 1.8 K at 0.14 MPa for the 4.7 nm channel and 0.89 K at 0.01 MPa for the 2.8 nm channel. For the latter, it is suppressed strongly under the application of pressure, and continuously approaches zero at around 2.1 MPa at absolute zero, which suggests a quantum phase transition between the superfluid and nonsuperfluid states in the 1D channel

Ni-P alloy-carbon black composite films fabricated by electrodeposition

Ni-P alloy-carbon black (CB) composite films were fabricated by electroplating and their microstructures and properties were examined. The CB and phosphorus contents of the composite films were also investigated. The CB particles were found to be embedded in the Ni-P alloy matrix. The CB content in the deposits increased, reached a maximum value of 0.77 mass% with increasing CB concentration in the bath up to 10 g dm(-3), and then decreased with a further increase in the CB concentration in the bath. Both before and after heat treatment, the composite films had higher hardnesses and lower friction coefficients than the Ni-P alloy films. Both before and after heat treatment, the friction coefficient of 0.77 mass% CB composite films was about half that of Ni-P alloy films without CB.ArticleAPPLIED SURFACE SCIENCE 256: 6914-6917(2010)journal articl

Stochastic Speculative Computation Method and its Application to Monte Carlo Molecular Simulation

Monte Carlo (MC) molecular simulation has significant computational complexity, and parallel processing is considered effective for computation of problems with large complexity. In recent years, multicore or many-core processors have gained significant attention as they enable computation with a large degree of parallelism on desktop computers. However, in conventional parallel processing, processes must be synchronized frequently; thus, parallel computing is not necessarily efficient. In this study, we evaluate the effect of applying MultiStart-based speculative parallel computation to MC simulations. Using probability theory, we performed theoretical verification to determine if speculative computation is more effective than conventional parallel computation methods. The parameters obtained from the theoretical calculations were observed in experiments wherein the speculative method was applied to an MC molecular simulation. In this paper, we report the results of the theoretical verification and experiments, and we show that speculative computation can accelerate MC molecular simulations

Electrodeposition of Ni-P Alloy-Multiwalled Carbon Nanotube Composite Films

Ni–P alloy–multiwalled carbon nanotube (MWCNT) composite films were fabricated by an electrodeposition technique, and their microstructure, hardness, and frictional properties were analyzed. Ni–P alloy–MWCNT composite films containing 20–22 atom % P and 0.7–1.2 mass % MWCNTs were electrodeposited from a composite plating bath. MWCNTs were embedded relatively uniformly in the Ni–P alloy matrix. The hardness of the composite films was higher than that of the Ni–P alloy films, both before and after heat-treatment, and the friction coefficient of the composite films was lower than that of the Ni–P alloy films.ArticleJOURNAL OF THE ELECTROCHEMICAL SOCIETY. 157(1):D50-D53 (2010)journal articl

Development and Control of Articulated Mobile Robot for Climbing Steep Stairs

In this paper, we develop an articulated mobile robot that can climb stairs, and also move in narrow spaces and on 3-D terrain. This paper presents two control methods for this robot. The first is a 3-D steering method that is used to adapt the robot to the surrounding terrain. In this method, the robot relaxes its joints, allowing it to adapt to the terrain using its own weight, and then, resumes its motion employing the follow-the-leader method. The second control method is the semi-autonomous stair climbing method. In this method, the robot connects with the treads of the stairs using a body called a connecting part, and then shifts the connecting part from its head to its tail. The robot then uses the sensor information to shift the connecting part with appropriate timing. The robot can climb stairs using this method even if the stairs are steep, and the sizes of the riser and the tread of the stairs are unknown. Experiments are performed to demonstrate the effectiveness of the proposed methods and the developed robot

Phosphorus Particle Composite Plating with Ni-P Alloy Matrix

Ni-P alloy films containing phosphorus particles (called Ni-P alloy composite films) were fabricated by electrodeposition and were subsequently subjected to heat-treatment. Their compositions and microstructures were characterized, and their friction properties were evaluated using a ball-on-plate method. Composite electroplating in the nickel sulfate and chloride bath containing phosphorus acid and micrometer-sized phosphorus particles resulted in the Ni-P alloy coating with enhanced deposit phosphorus content. The phosphorus content of the films increased with increasing phosphorus particle concentration in the composite plating baths, reaching a maximum value of 29.0 atom %. The phosphorus particles were homogeneously distributed in this Ni- 29.0 atom % P alloy composite film. Heat-treatment converted the phases of the alloy composite films from an amorphous phase to stable crystalline phases, which are the same as those in the Ni- P binary alloy phase diagram. The friction coefficients of the Ni- P alloy films increased with increasing cycle number, whereas those of the Ni- P alloy composite films remained relatively constant. The alloy composite films had lower friction coefficients than the Ni- P alloy films both before and after heat-treatment. These results indicate that phosphorus particles are beneficial for maintaining a lower and stable friction coefficient during the ball-on-plate reciprocating friction test.ArticleJOURNAL OF THE ELECTROCHEMICAL SOCIETY 156: D283-D286(2009)journal articl

Saccharification of lignocellulosic biomass under mild condition using ionic liquid

Biomass is expected to be an alternative resource to fossil resources. In this study, the development of a biomass conversion method into the valuable chemical, reducing sugar, was examined. For the conversion, thermochemical technology was focused on for its advantage of short reaction time, and ionic liquid was focused on as a reagent to overcome the unpreferable disadvantage of thermochemical technology, which is the low selectivity. Cedar and crystalline cellulose were pretreated with ionic liquid for reforming into desirable precursors of reducing sugar. Especially when they were pretreated by 1-ethyl-3-methylimidazolium methylphosphonate at 150°C for 1 h, the pretreatment worked effectively by decreasing the crystallinity of samples. Pretreated cedar and crystalline cellulose were converted into reducing sugar under hydrothermal conditions, respectively, by 39 C-% and 90 C-%. Recovery of ionic liquid was also examined. When cedar was used as a material, lignin was dissolved into ionic liquid through pretreatment, which was undesirable because of difficult separation thereof. When crystalline cellulose was used as a material, 98.3% of the ionic liquid was recovered after the conversion with the highest yield of reducing sugar (90 C-%)