«Quadrupole» mode DR filter for C-band applications

The possibility of reducing the radiation loss of dielectric resonator (DR) to the external environment has been investigated for the first time by applying higher order mode of DR, namely “quadrupole” type, with higher Q factor. The “quadrupole” mode for constructing narrow band-pass filter (<1%) has been studied. The resonant frequencies of dielectric resonator have been calculated on grounds of approximate analytical method as well as finite element method. The coupling coefficients of the rectangular DR with coplanar line have been scrutinized both as a function of the glass substrate’s height, namely bs, on which the DR is situated, and as a function of the DR’s displacement toward the center line, namely y₀. The synthesized two-resonator band-pass filter has the improved gain slope. The minimum value of insertion loss at the central frequency of 5.9 GHz is - 2.4dB, the shape factor is equal to 3.45

Flip Distance Between Triangulations of a Simple Polygon is NP-Complete

Let T be a triangulation of a simple polygon. A flip in T is the operation of removing one diagonal of T and adding a different one such that the resulting graph is again a triangulation. The flip distance between two triangulations is the smallest number of flips required to transform one triangulation into the other. For the special case of convex polygons, the problem of determining the shortest flip distance between two triangulations is equivalent to determining the rotation distance between two binary trees, a central problem which is still open after over 25 years of intensive study. We show that computing the flip distance between two triangulations of a simple polygon is NP-complete. This complements a recent result that shows APX-hardness of determining the flip distance between two triangulations of a planar point set.Comment: Accepted versio

Laryngeal chondrosarcoma (clinical case)

Laryngeal chondrosarcoma is a rare malignant tumor that originates from cartilage tissue. The incidence of this pathology varies from 1 to 12 %. Only isolated clinical cases of laryngeal chondrosarcoma and observations of small groups of patients with this disease are described  since statistical data on such rare types of tumors are often unavailable. Survival in this pathology may vary depending on various factors  such as the stage of the disease  the size of the tumor  the presence of metastases  the general condition of the patient and the effectiveness of treatment. Since laryngeal chondrosarcoma is a rare disease  there is relatively little scientific data on prognosis and survival. The article presents a clinical case of diagnosis of treatment and primary chondrosarcoma of the larynx