An efficient LP-based admissible heuristic for cost-based abduction

Cost-based abduction (CBA) is an important problem in reasoning under uncertainty. The CBA problem is NP-hard, and existing techniques have exponential worst-case complexity. This paper presents an admissible heuristic for CBA based on the use of linear programming to obtain an optimistic estimate of the cost-to-goal. The article then presents empirical results that indicate that the authors' method is efficient in comparison to Santos‘ integer linear programming method.     

An enhanced opinion retrieval approach via implicit feature identification

Journal of Intelligent Information Systems - Recently, there has been an enormous increase in the number of reviews of popular products. Therefore, opinion analysis has become a tedious task for...     

A mechanism for the corrodability of hafnium and the anodic oxide film thereon in HCl solutions

A study is made to account for the corrodability of each of the naturally developed and anodically formed oxide films on hafnium in HCl solutions. The behaviour of these oxide films was investigated by capacitance and potential measurements. The naturally developed oxide film grows spontaneously according to a direct logarithmic law. In diluted HCl (< 1 N), the rate of growth is small but the resultant film has better electrochemical insulating properties than that rapidly grown in the more concentrated solutions. On the other hand, the anodic oxide film is more liable to chemical (currentless) dissolution in HCl as the initial thickness increases. The rate determining step in the dissolution process is determined mainly by the oxide and is almost independent of the acid concentration. The behaviour of each of the two films has been correlated to changes in the fine structure of the parent oxide during its growth.     

Numerical study on maximum rebound ratio in blasting wave propagation along radian direction normal to joints

1 INTRODUCTION For one dimensional wave, such as seismic wave, passing across single joint or multiple parallel joints, combining the theory of displacement discontinuities and the method of characteristics, solutions in terms of magnitudes of the reflection ratio and the transmission ratio have been obtained by several researchers[1?6] for P-wave and S-wave respectively. However, for a practical dynamic problem in a rock mass involving blasting wave propagation from a tunnel or borehole,…     

Influence of cell geometry and mesh resolution on large eddy simulation predictions of flow around a single building

A number of research studies have employed a wide variety of test conditions to numerically assess flow field around buildings. In such studies, the employed mesh system and its resolution played a crucial role in determining the ultimate degree of solution accuracy. The objective of this study is to better establish a quantitative assessment of the influence of cell geometry and mesh resolution on the numerical predictions of large eddy simulation (LES) of the flow field around a single building. In order to achieve this objective, a number of mesh styles including conventional hexahedral-based mesh, tetrahedral-based mesh, and prism-based mesh have been considered. In addition, hybrid meshes of tetrahedron and hexahedron cells are also considered. In each mesh style, four grid resolutions were investigated: coarse, medium, fine, and very fine. Accuracy of the simulation has been assessed by applying comparisons to the experimental data available in literature. Moreover, quantitative grid convergence was calculated based on the grid convergence index, which accounts for the degree of grid refinement. Future studies are needed to analytically evaluate the influence of cell geometry on the solution accuracy and to more precisely evaluate other grid system options including various forms of hybrid configuration meshes.     

Equilibrium and kinetic studies on the extraction of gadolinium(III) from nitrate medium by di‐2‐ethylhexylphosphoric acid in kerosene using a single drop technique

The liquid–liquid extraction of Gd(III) from aqueous nitrate medium was studied using di‐2‐ethylhexylphosphoric acid (HDEHP) in kerosene. On the basis of the slope analysis data, the composition of the extracted species was found to be [Gd A₃(HA)] with the extraction equilibrium constant (K_ex) = (1.48 ± 0.042) × 10^?12 mol dm^?3. The results of the effect of temperature on the value of the equilibrium extraction constant indicated the endothermic character of the extraction system. The kinetics of the forward extraction of Gd³⁺ from nitrate medium by HDEHP in kerosene was investigated using the single drop column technique. The rate of flux (mass transfer per unit area) was found to be proportional to [Gd(III)], [H₂A₂]_(o), [NO₃^?], and [H⁺]^?1 in the liquid drop organic phase. The forward extraction rate constant, k_f, was 2.24 × 10^?3 m s^?1 using the equation: Copyright © 2005 Society of Chemical Industry     

Effect of large excavation on deformation of adjacent MRT tunnels

A large excavation of approximately 140 m wide, 200 m long and 15 m deep was made close to two Mass Rapid Transit (MRT) tunnels of 6 m diameter with invert depth of 15–27 m. In view of the scale and distance of excavation, significant effects on the MRT tunnels were expected. The paper presents the monitoring of the tunnel deformations during the excavation. A sophisticated monitoring system using a motorised total station was installed in the MRT tunnels to monitor their displacements and to ensure that the stringent requirements for safeguarding the tunnels were not violated during any part of the excavation works. The paper also presents the modelling of the excavation using a finite element program. The results obtained were reasonably close to the monitoring results. It was found that the stiffness of the tunnel lining has significant influence on the displacement and distortion of tunnels caused by an adjacent excavation. A stiffer lining undergoes less displacement and distortion but is likely to experience significantly greater bending moments.