Wojciech Walendziuk

High Frequency Electromagnetic Fields Analysis with the Use of the Parallel FDTD Method

In the paper the parallel algorithms of the Finite-Difference Time-Domain method are presented. Those algorithms are based on the space domain decomposition. In the presented work, communications among computation nodes in a cluster of PCs and the efficiency of the parallel algorithms are also discussed.

Parallel computation of the SAR distribution in a 3D human head model

This work presents a way of parallel computation of the Specific Absorption Rate distribution. The parallel program used in the computation was based on the FDTD (Finite-Difference Time-Domain) method [1,2,3]. In order to establish communication among the computational nodes, the MPI (Message Passing Interface) standard was used [4,5,6]. The presented example of a human head numerical model was built with the use of MRI (Magnetic Resonance Image) pictures.

Computer assisted uroflowmetry diagnostic system

In this paper an original uroflowmeter (called Adalbertus) has been presented. The device draws the flow chart and measures the parameters of urine flow. It is used in urological surgeries as an assistance in diagnosis of lower urinary track diseases like Benign Prostatic Hyperplasia (BPH). The measuring track and its main part - weight sensor have been described. Also the way of uncertainty calculation is mentioned. An example flow chart has been shown and the achieved results have been compared with a commercial product.

Testing a homogeneous cluster with the use of parallel benchmarks

Results of testing a homogeneous cluster of workstations with the use of commonly applied parallel benchmarks are described in the present paper. Some other procedures (parallel FDTD method) are also run in the cluster to determine its parameters influencing the efficiency of the computations.

Application of the speculative method to analysis of the dynamics of an asynchronous slip-ring motor

The speculative method is an original approach to the analysis of transient states appearing in electrical circuits in which the transient state is described by a system of linear or nonlinear ordinary differential equations. A general idea of this method is based on the decomposition of the time domain. Computations in the particular subintervals of time are conducted in parallel with the use of one of well-known numerical methods of solving ordinary differential equations systems. In this paper the analysis of the dynamics of an asynchronous slip-ring motor, as the example of the application of the speculative method, will be presented.

The Use of the Dynamic Space Decomposition Algorithm of a Computational Area in Heterogeneous Cluster Computations

This article presents an algorithm of the dynamic space decomposition being used in parallel methods of numerical simulations. This algorithm decomposes a numerical model defined by a rectangular grid of material data into subareas. These subareas are then assigned to particular computational nodes of a heterogeneous cluster system during initialisation of the computational process. The present work contains an example use of the algorithm applied to decompose the computational area in parallel implementation of the FDTD (finite-difference time-domain) method. The final part of the article contains the analysis of the decomposing algorithm in the form of the achieved speedup results of the parallel programme for various densities of the finite differences grid

ALTERNATIVE METHOD OF UPPER EXTREMITY FUNCTION ASSESSMENT OF STROKE PATIENTS BY ANGULAR KINEMATIC PARAMETERS

This study focuses on the functional assessment of the upper extremity of stroke patients via analysis of angular kinematics features. Amplitudes and angular velocities of multi-joint movements more precisely describe functional state at different impairment levels. However, the arm movement as a whole could be analyzed by means of joint angle–angle diagrams, which illustrate the 2D trajectory of upper extremity during movement and show the visual ranges of upper extremity in different cycles of motion. The functional range of motion of each upper extremity segment in all patient groups for more accurate assessment of capability was calculated. Moreover, we calculated the area (S) between two curves in joint angle–angle diagrams as a novel index of the complete upper extremity movement range evaluation. Our findings correspond to clinical rates and upper extremity assessment based on joint angle–angle diagrams seems to be a promising method for accurate assessment and/or predicting the outcomes of rehabilitation programs.

Analysis and application of two-current-source circuit as a signal conditioner for resistive sensors

Abstract The article presents the analysis of metrological properties of a two-current-source supplied circuit. It includes such data as precise and simplified equations for two circuit output voltages in the function of relative resistance increments of sensors. Moreover, graphs showing nonlinearity coefficients of both output voltages for two resistance increments varying widely are presented. Graphs of transfer resistances, depending on relative increments of sensors resistance were also created. The article also contains a description of bridge-based circuit realization with the use of a computer and a data acquisition (DAQ) card. Laboratory measurement of the difference and sum of relative resistance increments of two resistance decade boxes were carried out indirectly with the use of the created measurement system. Measurement errors were calculated and included in the article, as well.

A bridge-circuit for experimental simulation of quasi-static bending tests

A four-terminal (4T) bridge-circuit unconventionally supplied by two current sources connected in parallel to opposite arms, named double current bridge (2J) has been presented. This circuit has been applied for experimental stress analysis and worked with constantan foil strain gauges placed upon a beam. Some results of the measurements done with two-active-gauge bridge and four-active-gauge bridge have been described. Some advantages of these bridge-circuit, which could be used to the data acquisition during experimental measurements of a stress in a cantilever beam and a simply supported beam have been mentioned.

The distributed system for collecting and analysing selected medical data

In this paper the structure of a three-tiered distributed system for collecting and analysing medical examination data is presented. The idea of this work is to make an assistant tool for urologists to diagnose the lower urinary track diseases and their symptoms easier. The data (which are processed from the files made in the uroflowmeters - devices for measuring urine flow rate) are presented in web browser. It has been done with the use of PHP scripts which are accessed through Apache web server.