This paper presents analytical fan-beam and cone-beam reconstruction algorithms that compensate for uniform attenuation in single photon emission computed tomography. First, a fan-beam algorithm is developed by obtaining a relationship between the two-dimensional (2D) Fourier transform of parallel-beam projections and fan-beam projections. Using this relationship, 2D Fourier transforms of equiv...

This paper extends the theory of the Gröbner fan and Gröbner walk for ideals in polynomial rings to the case of submodules of free modules over a polynomial ring. The Gröbner fan for a submodule creates a correspondence between a pair consisting of a cone in the fan and a point in the support of the cone and a pair consisting of a leading monomial submodule (or equivalently, a reduced marked Gr...

When they reach a flat plain, rivers often deposit their sediment load into a cone-shaped structure called alluvial fan. We present a simplified experimental setup that reproduces, in one dimension, basic features of alluvial fans. A mixture of water and glycerol transports and deposits glass beads between two transparent panels separated by a narrow gap. As the beads, which mimic natural sedim...

The recently discovered deposits of a channelized fan located northeast of Holden Crater preserve a history of vertical and lateral accretion and avulsion of many channels, indicating water flowed freely across the surface of the fan during its construction. These sedimentary deposits, however, do not unambiguously discriminate between a deltaic or purely riverine origin for the feature. By usi...

The problem of the reconstruction of binary matrices from their fan-beam projections is investigated here. A fan-beam projection model is implemented and afterwards employed in systematic experiments to determine the optimal parameter values for a data acquisition and reconstruction algorithm. The fan-beam model, the reconstruction algorithm which uses the optimization method of Simulated Annea...

Many arid alluvial-fan terraces downwind from eolian sand sources exhibit an abrupt increase in Av-horizon thickness and sand content below a critical elevation which varies from fan to fan. Above this elevation, sand accumulates locally and is not transported across the fan. Below this elevation both coarse and fine eolian sand from nearby playa and channel sources is readily transported acros...

A topological drawing of a graph is fan-planar if for each edge e the edges crossing e have a common endpoint on the same side of e, and a fan-planar graph is a graph admitting such a drawing. Equivalently, this can be formulated by two forbidden patterns, one of which is the configuration where e is crossed by two independent edges and the other where e is crossed by incident edges with the co...

Simple to implement, low cost designs in CMOS Domino logic are presented. These designs require less transistors and are full Domino logic compatible while they attain better performance compared to the standard Domino logic implementations. Wide fan-in logic such as domino circuits is used in high-performance applications. Dynamic domino logic circuits are widely used in modern digital VLSI ci...

It is shown that the particular form of the frequency support of raw data and focused imagery obtained from an ultra-wideband, wide beamwidth synthetic aperture radar system can be exploited in nonseparable sampling schemes to reduce the overall amount of raw data samples and image pixels that need to be stored and computed. Furthermore, it is demonstrated that the constant integration angle ba...

A cavity-backed spiral antenna with ultra-wide band width is presented. By using a parabolic reflector, the radiation of the antenna becomes uni-directional, and the gain is promoted. The antenna is fed by a coaxial cut-away balun with fan-shaped patch which keeps a wideband impedance matching. The simulated bandwidth for VSWR < 2 covers 0.36 ~ 6.83GHz or bandwidth ratio of 19:1, and the gain a...