in this paper the reflection coefficient of electromagnetic wave incidence on the walls of the buildings and obstacles that occurs in mobile communication path was modified by solving the riccati nonlinear equations. for this purpose, the building walls are assumed inhomogeneous layers where their permittivity changes as function of the wall thickness. using this reflection coefficient, a new p...

This paper describes an improved model for multiple building diffraction modeling based on the uniform theory of diffraction (UTD). A well-known problem in conventional uniform theory of diffraction (CUTD) is multiple-edge transition zone diffraction. Here, higher order diffracted fields are used in order to improve the result; hence, we use higher order diffraction coefficients to improve a hy...

The diffraction of an inhomogeneous plane wave by an impedance wedge embedded in a lossy medium is analyzed. The rigorous integral representation for the field is asymptotically evaluated in the context of the uniform geometrical theory of diffraction (UTD) so that the asymptotic expressions obtained can be employed in a ray analysis of the scattering from more complex edge geometries located i...

This study describes systems submitted by the Center for Robust Speech Systems (CRSS) from the University of Texas at Dallas (UTD) to the 2016 National Institute of Standards and Technology (NIST) Speaker Recognition Evaluation (SRE). We developed 4 UBM and DNN i-vector based speaker recognition systems with alternate data sets and feature representations. Given that the emphasis of the NIST SR...

This paper describes the medical information retrieval (MIR) systems designed by the University of Texas at Dallas (UTD) for clinical decision support (CDS) which were submitted to the TREC 2014. We investigated the impact of various knowledge bases for automatic query expansion in the four officially submitted runs. Each of these systems exploits both Wikipedia and PubMed corpus statistics in ...

Human activity recognition (HAR) using smartphone sensors have been recently studied in various applications including healthcare, fitness, and smart home. Their accuracy often depends on high-quality feature design effectiveness of classification algorithms, where existing work mostly replies laborious hand-crafted shallow learning architecture. Recent deep techniques demonstrate outstanding p...

We present an algorithm for fast computation of diffraction paths for geometric-acoustics in complex environments based on the UTD formulation. Our method extends ray-frustum tracing to efficiently compute paths in the shadow region caused by long diffracting edges. Our approach can handle general scenes with moving sources, receivers, and dynamic objects. We evaluate the accuracy through compa...

The paper deals with a study of diffraction on dielectric wedge (building corner) in millimeter frequency band, both theoretically and experimentally, to provide knowledge support for ray tracing/launching calculations of MWS interference issues in urban areas. The main motivation was to find balance between reasonably reliable results and necessary demands on calculation complexity and input d...

This work presents an algorithm to perform radiowave coverage predictions in urban environments using the Uniform Theory of Diffraction (UTD). The ray-tracing algorithm is based on the image theory for a quasi-3D environment. Multiple reflections and diffractions are considered through the separation of multipath components into four different classes, used to determine the scattered field. The...

This paper describes our system for the task of extracting frame semantic structures in SemEval–2007. The system architecture uses two types of learning models in each part of the task: Support Vector Machines (SVM) and Maximum Entropy (ME). Designed as a pipeline of classifiers, the semantic parsing system obtained competitive precision scores on the test data.