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Number of results: 6
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Abstract

This study is focused on experimental investigation of selected type of brazed plate heat exchanger (PHEx). The Wilson plot approach was applied in order to estimate heat transfer coefficients for the PHEx passages. The main aim of the paper was to experimentally check ability of several correlations published in the literature to predict heat transfer coefficients by comparison experimentally obtained data with appropriate predictions. The results obtained revealed that Hausen and Dittus-Boelter correlations underestimated heat transfer coefficient for the tested PHEx by an order of magnitude. The Aspen Plate code overestimated heat transfer coefficient by about 50%, while Muley-Manglik correlation overestimated it from 1% to 25%, dependent on the value of Reynolds number and hot or cold liquid side.

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Authors and Affiliations

Janusz T. Cieśliński
Artur Fiuk
Krzysztof Typiński
Bartłomiej Siemieńczuk
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Abstract

In the study a new proposal of convective velocity determination necessary for eddy size determination from the dissipative range in a turbulent flow in a mixer was made. The proposed quantity depends on all the mean and fluctuating velocity components. By applying convective velocity one may determine the distribution of time and linear Taylor microscale in a stirred vessel.

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Authors and Affiliations

Tomasz Kurasiński
Czesław Kuncewicz
Jacek Stelmach
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Abstract

In this paper we present results of systematic and comprehensive simulation analysis of the Tsao & Safonov unfalsified controller for complex robot manipulators. In particular, we show that the controller falsification procedure yields the closedloop unfalsified controller, which accomplishes the control objective, within a finite and relatively short time interval with the number of invocations of linear programming based unfalsified controller selection procedure being relatively small. We also present some conclusions resulting from the investigation of the effect of such elements as manipulator structure complexity, prior knowledge about disturbances, reference trajectory and assigned closed-loop spectrum on unfalsified controller performance and computational complexity.

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Authors and Affiliations

M. Pawluk
K. Arent
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Abstract

The problems of identification of objects have been strictly bound with sea navigation for a long time. The article presents a method of object identification by means of artificial neural networks. The classification of objects is effected on the basis of a radio signal. A comparison between classical methods and neural methods has been made. The results of research performed have been presented on real data, and a detailed analysis of the probabilistic network and its identification.
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Authors and Affiliations

Andrzej Stateczny
Tomasz Praczyk
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Abstract

A i m s: Gestational diabetes mellitus (GDM) is an emerging worldwide problem. Changes in clinical characteristics of women affected by GDM in a long-term perspective are still not properly investigated. We aimed to examine such changes over a decade in a retrospective single-center analysis.
M e t h o d s: The medical documentation from Department of Metabolic Diseases, Krakow, Poland was analyzed. We included 633 women consecutively diagnosed with GDM in one of three time intervals: 2007–2008 (N = 157), 2012–2013 (N = 272), 2016–2017 (N = 234). Statistical analyses were performed.
R e s u l t s: Comparison of the three groups identified differences in the mean age of women at the GDM diagnosis (30.7 ± 5.0 years vs. 31.2 ± 4.7 vs. 32.5 ± 4.7, respectively, starting from the earliest 2007–2008 group), pregnancy week at GDM diagnosis (28.0 ± 5.3 wks. vs. 25.9 ± 4.9 vs. 23.4 ± 6.8), the proportion of women diagnosed before the 24th week of pregnancy (12.8% vs. 16.5% vs. 31.3%), and gestational weight gain (12.4 ± 5.0 kg vs. 10.4 ± 5.2 vs. 10.0 ± 5.7); (p = 0.001 or less for all comparisons). We also found differences for glucose values on fasting and at 2 hours with the highest (0 min) and lowest level (120 min) in the 2016–2017, respectively. Finally, a borderline difference for the weight, but not for BMI, was found (64.1 ± 14.1 kg vs. 66.2 ± 13.1 vs. 67.8 ± 15.6; p = 0.04). Differences were also identified in the post hoc analysis between cohorts.
C o n c l u s i o n: This retrospective analysis illustrates changes in characteristics of women with GDM occurring over the period of decade in Poland. They likely result from both epidemiological trends and modifications of the WHO criteria for the GDM diagnosis.
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Bibliography

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2. Lowe L.P., Metzger B.E., Dyer A.R., et al.: Hyperglycemia and Adverse Pregnancy Outcome (HAPO) Study: associations of maternal A1C and glucose with pregnancy outcomes. Diabetes Care. 2012; 35: 574–580.
3. Gortazar L., Flores-Le Roux J.A., Benaiges D., et al.: Trends in prevalence of gestational diabetes and perinatal outcomes in Catalonia, Spain, 2006 to 2015: the Diagestcat Study. Diabetes Metab Res Rev. 2019; 35: e3151.
4. Cade T.J., Polyakov A., Brennecke S.P.: Implications of the introduction of new criteria for the diagnosis of gestational diabetes: a health outcome and cost of care analysis. BMJ Open. 2019; 9: e023293.
5. Mack L.R., Tomich P.G.: Gestational Diabetes: Diagnosis, Classification and Clinical Care. Obstet. Gynecol. Clin. North Am. 2017; 44: 207–217.
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7. Lean S.C., Derricott H., Jones R.L., et al.: Advanced maternal age and adverse pregnancy outcomes: A systematic review and meta-analysis. PLoS One. 2017; 12: e0186287.
8. Chiefari E., Arcidiacono B., Foti D., et al.: Gestational diabetes mellitus: an updated overview. J Endocrinol Invest. 2017; 40:.899–909.
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13. 2020 Guidelines on the management of diabetic patients. A position of Diabetes Poland. Clinical Diabetology, supplement A, 2014.
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15. Molina-García L., Hidalgo-Ruiz M., Cocera-Ruíz E.M., et al.: The delay of motherhood: Reasons, determinants, time used to achieve pregnancy, and maternal anxiety level. PLoS One. 2019; 14: e0227063.
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Authors and Affiliations

Magdalena Wilk
1 2
Katarzyna Cyganek
1 2
Bartłomiej Matejko
1 2
Sabina Krzyżowska
1 2
Izabela Lasoń
1 2
Barbara Katra
1 2
Joanna Zięba-Parkitny
2
Przemysław Witek
1 2
Maciej T. Małecki
1 2

  1. Department of Metabolic Diseases, Jagiellonian University Medical College, Kraków, Poland
  2. University Hospital, Kraków, Poland
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Abstract

Changes taking place in weathered bedrock and vegetation of the ground moraine of Werenskiold glacier during about 50 years are presented. These results are based on phytosociological survey and analysis of the population structure of Saxifraga oppositifolia in 20 experimental fields and the analysis of physical and chemical features of the soils. In the process of succession, with chemical features not much changed and spongy structure just beginning, the number of vascular plants did not increase. In the process of succession the gradual increase in the density of S. oppositifolia population was observed. The size of its individuals and the share of flowering individuals also increased.

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Authors and Affiliations

Ewa Pirożnikow
Andrzej Górniak

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