Marek Kaminski

Dynamic thermal modelling of a power integrated circuit with the application of structure functions

This paper presents dynamic thermal analyses of a power integrated circuit with a cooling assembly. The investigations are based on the examination of the cumulative and differential structure functions obtained from the circuit cooling curves recorded during transient circuit temperature measurements. The experiments carried out and the comprehensive study of the computed structure functions rendered possible determination of the interface contact resistance and the heat transfer coefficient values necessary for numerical thermal simulations illustrating the influence of these thermal model parameters on circuit temperature.

Real-time prediction of acute cardiovascular events using hardware-implemented Bayesian networks

This paper presents a decision support system that aims to estimate a patient׳s general condition and detect situations which pose an immediate danger to the patient׳s health or life. The use of this system might be especially important in places such as accident and emergency departments or admission wards, where a small medical team has to take care of many patients in various general conditions. Particular stress is laid on cardiovascular and pulmonary conditions, including those leading to sudden cardiac arrest. The proposed system is a stand-alone microprocessor-based device that works in conjunction with a standard vital signs monitor, which provides input signals such as temperature, blood pressure, pulseoxymetry, ECG, and ICG. The signals are preprocessed and analysed by a set of artificial intelligence algorithms, the core of which is based on Bayesian networks. The paper focuses on the construction and evaluation of the Bayesian network, both its structure and numerical specification.

Applications of Ray-Casting in Medical Imaging

The authors present applications of ray casting as segmentation and analysis method for processing of medical imaging data. The first application features ray casting based image segmentation for extraction of a region enclosing heart structures from a series of CT scans. Proposed method yields significant gains in reduction of the data set size, that are of importance in applications such as Transesophageal USG simulations on mobile devices or web platforms.

Assessment of interleukin-6, interleukin-8 and interleukin-18 count in the serum of IUGR newborns

Abstract Aim: Aim of this study was to assess concentrations of interleukin-6 (IL-6), interleukin-8 (IL-8) and interleukin-18 (IL-18) in the serum of newborns with diagnosed intrauterine growth restriction (IUGR) in comparison to concentrations in serum of newborns with weight appropriate for gestational age (AGA). Materials: Research was conducted at the Lodz Medical University Clinic of Neonatology during 2010–2011. Surveyed group consisted of 50 hypotrophic full-term infants of single pregnancies (average weight: 2329 ± 287 g); control group, enclosing 50 infants AGA (average weight: 3544 ± 2161 g). Both groups received average Apgar score of 9 points. Concentrations of analysed cytokines were marked between 4–6 hours after birth. The enzyme-linked immunosorbent assay (ELISA) test was used to determine interleukins concentrations. Study was prospective. Statistics on the data were conducted with the Kolmogorov–Smirnov test. Significance level: p < 0.05. Results: Concentrations of IL-6 and IL-18 were elevated in the IUGR group in a statistically significant manner in comparison to the control group. Conclusions: An elevated level of IL-6 and IL-18 in the IUGR group, comparing to control group, signifies the existence of inflammation in the process of developing IUGR, therefore, screening tests estimating levels of interleukins as IL-6 and IL-18 might be clinically useful in predicting the occurrence of IUGR and help preventing it.

Application of structure functions for the investigation of forced air cooling

This paper presents thermal analyses of a power amplifier placed in a wind tunnel. All the investigations are based on the transient temperature measurements performed during the circuit cooling process. The measured cooling curves were used to compute the cumulative and differential structure functions for the circuit with a heat sink. These functions helped to determine the optimal values of circuit model parameters necessary for numerical thermal simulations. The experiments demonstrated the influence of the wind speed on the value of the heat transfer coefficient and consequently on the temperature of the entire structure.

Application of RC Equivalent Networks to Modelling of Nonlinear Thermal Phenomena

The main goal of this paper is to present an extension of a numerical solver dedicated to thermal simulation of electronic structures. This solver implements the finite difference method and employs the RC equivalent network approach. The hereby-proposed extension renders possible thermal simulation taking into account non-linear cases when material thermal properties and heat transfer coefficient values depend on temperature. For this purpose, the standard equivalent RC circuit method has been significantly modified. All the required modifications are presented in this paper in detail. Additionally, the differences between the results obtained with both the linear and non-linear simulators have been compared and discussed based on the examples of selected test structures.

Layout based thermal simulations of 3D integrated circuits

In this paper, a three-dimensional (3D) thermal simulations of basic integrated circuit (IC) components are presented. The layout of the real application specific integrated circuit (ASIC) generated in CAD CADENCE software were loaded into the CFD-ACE environment, where the 3D thermal simulation was done. The influence of many heating points was considered in simulations. Comparison among several cooling conditions was also made and presented in the paper.

Economic Optimization of an Underground Power Cable Installation

This paper presents a mathematical model for the selection of an optimal power cable conductor cross section and the dimensions of a corrective backfill. To this end, a detailed model for the calculation of the life-cycle cost of cable ownership is presented. The formula considers the material and labor costs in the production of a power cable as well as the cost of losses during its operation. Simultaneously, the procedure seeks the optimal size of the corrective backfill, taking ampacity constraints into account. Since the formulation is complex, a genetic algorithm is proposed to solve the optimization problem. A real-life numerical example is presented.

Evaluation of the impact of atmospheric pressure in different seasons on blood pressure in patients with arterial hypertension.

OBJECTIVES Atmospheric pressure is the most objective weather factor because regardless of if outdoors or indoors it affects all objects in the same way. The majority of previous studies have used the average daily values of atmospheric pressure in a bioclimatic analysis and have found no correlation with blood pressure changes. The main objective of our research was to assess the relationship between atmospheric pressure recorded with a frequency of 1 measurement per minute and the results of 24-h blood pressure monitoring in patients with treated hypertension in different seasons in the moderate climate of the City of Łódź (Poland). MATERIAL AND METHODS The study group consisted of 1662 patients, divided into 2 equal groups (due to a lower and higher average value of atmospheric pressure). Comparisons between blood pressure values in the 2 groups were performed using the Mann-Whitney U test. RESULTS We observed a significant difference in blood pressure recorded during the lower and higher range of atmospheric pressure: on the days of the spring months systolic (p = 0.043) and diastolic (p = 0.005) blood pressure, and at nights of the winter months systolic blood pressure (p = 0.013). CONCLUSIONS A significant inverse relationship between atmospheric pressure and blood pressure during the spring days and, only for systolic blood pressure, during winter nights was observed. Int J Occup Med Environ Health 2016;29(5):783-792.

Fusion of morphological data obtained by coronary computed tomography angiography with quantitative echocardiographic data on regional myocardial function.

BACKGROUND Three-dimensional (3D) fusion of morphological data obtained by coronary computed tomography angiography (CCTA) with functional data from resting and stress echocardiography could potentially provide additional information compared to examination results analyzed separately and increase the diagnostic and prognostic value of non-invasive imaging in patients with suspected coronary artery disease (CAD). Using vendor-independent software developed in our institution, we aimed to assess the feasibility and reproducibility of 3D fusion of morphological CCTA data with echocardiographic data regarding regional myocardial function. METHODS Thirty patients with suspected CAD underwent CCTA and resting transthoracic echocardiography. From CCTA we obtained 3D reconstructions of coronary arteries and left ventricle (LV). Offline speckle-tracking analysis of the echocardiographic images provided parametric maps depicting myocardial longitudinal strain in 17 segments of the LV. Using our software, 3 independent investigators fused echocardiographic maps with CCTA reconstruc-tions in all patients. Based on the obtained fused models, each segment of the LV was assigned to one of the major coronary artery branches. RESULTS Mean time necessary for data fusion was 65 ± 7 s. Complete agreement between independent investigators in assignment of LV segments to coronary branches was obtained in 94% of the segments. The average coefficient of agreement (kappa) between the investigators was 0.950 and the intra-class correlation coefficient was 0.9329 (95% CI 0.9227-0.9420). CONCLUSIONS Three-dimensional fusion of morphological CCTA data with quantitative echocardiographic data on regional myocardial function is feasible and allows highly repro-ducible assignment of myocardial segments to coronary artery branches.