Interactions of a sub-surface crack with a center of dilatation in an elastic half-plane

This paper examines the interaction between a crack parallel to the free surface of an elastic half-plane and an internal center of dilatation. The problem is decomposed into two auxiliary problems. When the center of dilatation approaches the crack tip, two kinds of singularity are analytically obtained. If the overburden stress and the friction on crack surface are neglected, both modes I and II stress intensity factors (K_I and K_II) are induced at the crack tips. The maximum of K_I and K_II occurs when the center of dilatation is located in front of the crack tips. The tensile cracking is likely to be prohibited by the overburden stress, while shear cracking remains possible even including the effects of both overburden and friction on the crack surface.     

Use of nonlinear methods to assess effects of clonidine on blood pressure in spontaneously hypertensive rats

In spontaneously hypertensive rats (SHR), chronic infusion of clonidine failed to decrease blood pressure and blood pressure variability. We used nonlinear methods to get a deeper insight on the effects of clonidine on blood pressure dynamics. For 24 h and 4 wk, clonidine (0.1 mg . kg-1 . day-1 sc) was infused by minipumps in the conscious SHRs, and, for comparison, a vehicle was infused in SHRs and in Wistar-Kyoto rats. Blood pressure was recorded for 30 min before and after treatments. We used the Lyapunov exponent, approximated by the inverse of the lmax index derived from the recurrence plot method, to characterize nonlinear dynamics. Before treatment, lmax index of blood pressure was lower (P < 0.01) in the SHRs than in the Wistar-Kyoto rats. Clonidine significantly increased lmax (P < 0.01) to the level observed in normotensive rats, at 24 h and up to 4 wk after infusion. We conclude that clonidine has a significant chronic effect on blood pressure dynamics, as evidenced by nonlinear methods. Our study also suggests that the mechanisms governing blood pressure variations are nonlinear.     

Treatment of congestive heart failure in the elderly: emphasis on renal functional changes and impact of therapy

Congestive heart failure (CHF) is a syndrome in which the kidney plays a fundamental role, as sodium retention is a hallmark of the syndrome. An additional hallmark of CHF is that it affects the elderly disproportionately. This high incidence of CHF in the elderly is complicated by age-related alterations in renal hemodynamics and tubular function. In view of these age-related renal alterations, pharmacologic therapy for CHF in the elderly needs to be closely monitored. In addition, recent understanding of neurohumoral mechanisms of CHF has led to new therapeutic options for the treatment of CHF, which are reviewed here.     

Computer-aided geometric design and panel generation for hull forms based on rational cubic Bézier curves

For generation of hull forms, a method using rational cubic Bézier curves is chosen because of their superior segmentwise local-weighted behavior. A hull form is defined by two sets of grid lines—transverse grid lines arranged in length direction and longitudinal grid lines arranged in depth direction. Transverse lines are first defined, the points on the transverse lines with the same curve parameter values are then fitted to define longitudinal lines. Thereby, each curve is described by a rational cubic Bézier curve in space. The bilge, flat side and flat bottom can be defined precisely and more flexibilities are provided for defining bow and stern regions. By the way, a hull surface can be generated which is useful to produce desired data for hydrostatic or panel generations.     

Cyclic-cubes: a new family of interconnection networks of evenfixed-degrees

We introduce a new family of interconnection networks that are Cayley graphs with fixed degrees of any even number greater than or equal to four. We call the proposed graphs cyclic-cubes because contracting some cycles in such a graph results in a generalized hypercube. These Cayley graphs have optimal fault tolerance and logarithmic diameters. For comparable number of nodes, a cyclic-cube can have a diameter smaller than previously known fixed-degree networks. The proposed graphs can adopt an optimum routing algorithm known for one of its subfamilies of Cayley graphs. We also show that a graph in the new family has a Hamiltonian cycle and, hence, there is an embedding of a ring. Embedding of meshes and hypercubes are also discussed     

Coloured Petri net‐based modeling for distributed relational database queries

Abstract

In this paper, a new application of colour timed Petri net (CTPN) based methodology for distributed relational database queries modeling and corresponding simulation is addressed. This work, first based on parsed query definitions, converts logical query plans into designed CTPN models. Later, the improved cost‐based functions are then established and appended to CTPN with a general purpose CPN simulator‐Design/CPN to observe the thresholds of query operations. The propose CTPN can be used in the design phase as an experimental prototype to automatically simulate distributed database query processing which, in turn, may considerably reduce the load of developing the actual query processing software in the logical design phase of a distributed database system. Also, since all the essential details of query processing in CTPN have been simulated, the results of this study can be closely related to real world applications.     

Power dissipation of VLSI array processing systems

The Power Factor Approximation (PFA) power estimation method is reviewed and applied to VLSI array processing systems. The power dissipation of 1, 2, and 3 dimensional algorithms implemented on linear, hexagonal, and cubic processor arrays is investigated. Closed form equations are developed which show how the overall power dissipation is influenced by an algorithm's size and dimensionality, the target array processor's size and dimensionality, and the adopted partitioning strategy. The power estimation methods developed in this paper can be applied in the early phases of VLSI algorithm/architecture design, selection, and partitionment. The power dissipation of a matrix-matrix multiplication operation is estimated as an example application.This work was supported in part by the Hughes Aircraft Company fellowship program and the NSF initiation grant MIP-99-10437.     

Reverse shearing of shear bands in polystyrene

Shear bands produced in polystyrene by compression can be reverse sheared by a second compression in a perpendicular direction. The net shear strain can be zero or negative. Like the forward shear, the reverse shear also produces a ridge on the surface. The height of the ridge seems to be proportional to the reverse shear strain. On the side surface the reverse shear produces a step whose height increases at an average rate of 1.17 mm sec^–1 (at a crosshead speed of 1 mm sec^–1), estimated by high-speed cinematography at 1000 frames sec^–1. During the reverse shear the second compression experiences a yield drop whose size increases with the forward strain due to the first compression. The implications of these results are discussed.     

Prediction of facial attractiveness from facial proportions

This study investigates the relationship between facial attractiveness and facial proportions. Here, we generated facial images with different proportions using computer software, hence avoided the influence of hairstyle, facial expression as well as skin tone and texture on the perception of facial attractiveness. By analyzing the relationship between the facial proportions of 432 computer generated facial images and their attractiveness ratings, here we identified the optimum proportions for an attractive female face and further established a model of predicting facial attractiveness from four principle components of facial proportions with good predictability (R²=0.64).