A four-dimensional Walker geometry is a four-dimensional manifold M with a neutral metric g and a parallel distribution of totally null two-planes. This distribution has a natural characterization as a projective spinor field subject to a certain constraint. Spinors therefore provide a natural tool for studying Walker geometry, which we exploit to draw together several themes in recent explicit...

A four-dimensional Walker geometry is a four-dimensional manifold M with a neutral metric g and a parallel distribution of totally null two-planes. This distribution has a natural characterization as a projective spinor field subject to a certain constraint. Spinors therefore provide a natural tool for studying Walker geometry, which we exploit to draw together several themes in recent explicit...

A four-dimensional Walker geometry is a four-dimensional manifold M with a neutral metric g and a parallel distribution of totally null two-planes. This distribution has a natural characterization as a projective spinor field subject to a certain constraint. Spinors therefore provide a natural tool for studying Walker geometry, which we exploit to draw together several themes in recent explicit...

Machines based on parallel kinematics typically utilize connector geometry to establish the kinematic state of the moving platform. Most active applications require the connectors to be both prime movers and sensors. In some applications, the connectors are passive, with a metrology function of determining moving platform position and orientation. A methodology is developed that generates optim...

Steam reforming integrated with oxidation of methanol was considered with numerical simulation. The parallel micro-channels with circular cross sections were used. Because when the catalytic deposited inside the rectangular micro-channels, it fills up the edges. Hence, the approximation of a cylindrical channel is appropriate. Effect of this changing in cross section was considered and results ...

the subject of geometry and proportions has been regarded as an issue which has a close relationship with architecture. since the entire universe, living beings and the human geometry can be seen clearly, that’s why our unconscious essence has accustomed to these proportions whereby reflection of this mentality can be seen in the architect’s hands and thought in the architecture. it can witness...

The group-invariant geometry on real and complex n-balls is hyperbolic geometry, if one pursues classical geometric notions in this context, in the sense that there are infinitely many straight lines (geodesics) through a given point not on a given straight line, thus contravening the parallel postulate for Euclidean geometry. We will not consider classical geometric notions here, since the tra...

The group-invariant geometry on real and complex n-balls is hyperbolic geometry, in the sense that there are infinitely many straight lines (geodesics) through a given point not on a given straight line, thus contravening the parallel postulate for Euclidean geometry. We will not directly consider geometric notions, since the transitive group action determines structure in a more useful form. S...