Mapping Datalog program execution to networks of processors

The problem of mapping the parallel bottom up execution of Datalog programs to an interconnected network of processors is studied. The parallelization is achieved by using hash functions that partition the set of instantiations for the rules. We first examine this problem in an environment where the number of processors and the interconnection topology is known, and communication between program segments residing at non-adjacent processors is not permitted. An algorithm is presented that decides whether a given Datalog program can be mapped onto such an architecture. We then relax the constraint on the architecture by allowing program segments residing at non-adjacent processors to communicate, A theory of approximate mappings is developed, and an algorithm to obtain the closest approximate mapping of a given Datalog program onto a given architecture is presented     

Role of zirconium addition on stability of UAl3 phase in Al---U system

The microstructural changes of Al-22 wt%U and Al-46 wt%U alloys containing 3 wt% Zr were investigated after heat treatment at 620°C for 1 to 45 days. Though it is reported that addition of 3 wt% Zr stabilizes the (U,Zr)Al₃ phase at room temperature, the present investigation shows that the (U,Zr)Al₃ phase is not stable but slowly transforms to the U_0.9Al₄ phase. The high temperature creep curves generated for these ternary alloys showed a wavy pattern which also suggests that the (U,Zr)Al₃ phase is not stable.     

Rare earth cobaltite catalysts: Relation of activity to spin and valence states of cobalt

Catalytic activities of rare earth cobaltites and related compounds are shown to be related to the spin and valence states of cobalt.     

Betadrenoceptors in urinary bladder

When rat peroneal nerves were fixed under 5 different fixation schedules with various osmolalities (310, 410 and 900 milliosmoles), the frequency of abnormality of mitochondria in the axoplasm was lowest in myelinated fibers fixed with 6% glutaraldehyde in 0.1 M cacodylate buffer (900 milliosmoles). The relationship of axonal area to number of myelin lamellae was significantly different between high-osmolality fixation and low-osmolality fixation. Assuming that the number of myelin lamellae remains the same with fixation, there was a significant shrinkage in the axonal area of fibers with high-osmolality fixation. The amount of shrinkage was less in larger fibers than in smaller fibers fixed at high osmolality.     

Dilatometric technique for evaluation of the kinetics of solid-state transformation of maraging steel

Solid-state transformation kinetics of a 350 grade commercial maraging steel were investigated using a nonisothermal dilatometric technique. Two solid-state reactions—namely, precipitation of intermetallic phases from supersaturated martensite and reversion of martensite to austenite—were identified. Determination was made of the temperatures at which the rates of these reactions reached a maximum at different heating rates. The kinetics of the individual reactions in terms of activation energy were analyzed by simplified procedures based on the Kissinger equation. An estimated activation energy of 145 ± 4 kJ/mol for the precipitation of intermetallic phases was in good agreement with reported results based on the isothermal hardness measurement technique. Martensite to austenite reversion was associated with an activation energy of 224 ± 4 kJ/mol, which is very close to the activation energy for diffusion of substitutional elements in ferrite. Results were supplemented with microstructural analysis.     

Limiting current in gyrotrons

Analytical expression for the space charge limited current is derived on the basis of a simplified model. Numerical data for wide ranging beam and geometrical parameters are presented.     

Pyroelectric detection properties of gadolinium molybdate (gmo)

The pyroelectric detection properties of gadolinium molybdate (GMO) crystals have been studied near and at its 159°C ferroelectric transition temperature. Responsivity and detectivity figures of merit are calculated from measurements of pyroelectric currents induced by white light irradiation and are compared with room temperature figures of merit for TGS and SBN detectors. Since GMO does not exhibit a dielectric anomaly, it can be used as a threshold detector by heating through the transition temperature from a pre-selected temperature increment below the transition. Voltage-sensitive pyroelectric currents at the transition, found previously, permit voltage control of the threshold.     

Hydromagnetic stability of helical flows permeated by a magnetic field with a radial component

In this paper, we have studied the linear stability of the nondissipative helical flow of an incompressible perfectly conducting fluid between two concentric cylinders permeated by a non-zero radial magnetic field. It is found that a rigidly rotating column of a perfectly conducting fluid permeated by a magnetic field [($\text{A/r}$), ($\text{C/r}$), $\text{B}{}_0$], where $\text{A, C, B}{}_0$ are constants, is stable for all infinitesimal disturbances.