This paper describes the application of the Finite-Volume Time-Domain (FVTD) method to characterize the influence of the substrate on Archimedean spiral antennas. The unstructured mesh of the FVTD method permits to model precisely the fine spiral structure and the thin underlying substrate. Time-domain numerical results permit to demonstrate how the substrate affects the distribution of current...

We present Smoothed Particle Hydrodynamics (SPH) simulations of the response of gas discs to a spiral potential. These simulations show that the commonly observed spurs and feathering in spiral galaxies can be understood as being due to structures present in the spiral arms that are sheared by the divergent orbits in a spiral potential. Thus, dense molecular cloud-like structures generate the p...

PURPOSE To compare prospectively the accuracy of spiral computed tomography (CT) with that of ventilation-perfusion scintigraphy for diagnosing pulmonary embolism. MATERIALS AND METHODS Within 48 hours of presentation, 142 patients suspected of having pulmonary embolism underwent spiral CT, scintigraphy, and (when indicated) pulmonary angiography. Pulmonary angiography was attempted if interp...

We expand our pervious numerical study of the properties of the stellar velocity distribution within the disk of a twoarmed spiral galaxy by considering spiral stellar density waves with different global Fourier amplitudes, C2. We confirm our previous conclusion that the ratio σ1 : σ2 of smallest versus largest principal axes of the stellar velocity ellipsoid becomes abnormally small near the o...

The problem of constructing a set of uniformly-distributed points on the surface of a sphere, also known as the Thomson problem, has a long and interesting history, which dates back to J.J. Thomson in 1904. A particular variant of the Thomson problem that is of great importance to biomedical imaging is that of generating a nearly uniform distribution of points on the sphere via a deterministic ...

Background: This study assessed the application value of 64-slice spiral computed tomography angiography (CTA) in a follow-up evaluation of patients receiving coronary stent implantation. Materials and Methods: A total of 468 patients who underwent percutaneous coronary intervention (PCI) at our hospital between January 2013 and October 2016 were selected for this study. Coronary angiography an...

In recent years, the popularity of wireless inductive power transfer (WIPT) system for electric vehicle battery charging (EVBC) is always ever-increasing. In the WIPT inductively coupled coil structure is the heart of the system and the mutual inductance (MI) between the coupled coils is the key factor for effective power transfer. This paper presents the analysis of mutual inductance between t...

Background: Prospectively electrocardiography (ECG)-triggered high-pitch spiral coronary computed tomography angiography (CCTA) is a unique scan mode for dual-source CT (DSCT). Our reports aim to compare image quality and radiation dose of CCTA using high-pitch spiral or sequential acquisition mode in patients with low and stable heart rates. Materials and Methods: Patients with low and stable ...

Spiral Architecture is a relative new and powerful approach to machine vision system. The geometrical arrangement of pixels on Spiral architecture can be described in terms of a hexagonal grid. However, all the existing hardware for capturing image and for displaying image are produced based on rectangular architecture. It has become a serious problem affecting the advanced research on Spiral A...

The drift behavior of spiral waves under the influence of a polarized electric field is investigated in the light that both the polarized electric field and the spiral waves possess rotation symmetry. Numerical simulations of a reaction-diffusion model show that the drift velocity of the spiral tip can be controlled by changing the polarization mode of the polarized electric field and some inte...