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  • Author: Paweł Rutkowski x
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Open access

Kamil Kornaus, Agnieszka Gubernat, Dariusz Zientara, Paweł Rutkowski and Ludosław Stobierski

Abstract

Previous studies concerning pure tungsten carbide polycrystalline materials revealed that nanolayers of graphite located between WC grains improve its thermal properties. What is more, pressure-induced orientation of graphene nano platelets (GNP) in hot pressed silicon nitride-graphene composites results in anisotropy of thermal conductivity. Aim of this study was to investigate if addition of GNP to WC will improve its thermal properties. For this purpose, tungsten carbide with 0.5–6 wt.% of GNP(12)-additive underwent hot pressing. The microstructure observations performed by SEM microscopy. The anisotropy was determined via ultrasonic measurements. The following mechanical properties were evaluated: Vickers hardness, bending strength, fracture toughness KIc. The influence of GNP(12) addition on oxidation resistance and thermal conductivity was examined. It was possible to manufacture hot-pressed WC-graphene composites with oriented GNP(12) particles, however, the addition of graphene decreased both thermal and mechanical properties of the material.

Open access

Robert Rozwałka, Tomasz Rutkowski and Paweł Bielak -Bielecki

Abstract

In Central Europe, as well as in Poland many introduced spider species have been recorded in the past decades. Most of them are from areas with warm climate, and spreading mainly in synanthropic environment, rarely colonizing natural habitats. Results of research, presented in this paper extend the list of Polish synanthropic araneofauna by four species: Latrodectus mactans, Cheiracanthium mildei, Heteropoda venatoria and Heliophanus cf. apiatus. In addition, new findings of rare or rarely collected synanthropic spider species (Nesticella mogera, Scytodes thoracica, Psilochorus simoni, Uloborus plumipes, Parasteatoda tabulata, Steatoda triangulosa, Mermessus trilobatus, Ostearius melanopygius, Hasarius adansoni, Leptorchestes berolinensis, Pseudeuophrys lanigera) are discussed. Presented data enrich our knowledge about distribution of these species in Poland and show new pathways of potential expansion. For Uloborus plumipes and Hasarius adansoni presence of stable, permanent populations is shown. Findings of Mermessus trilobatus and Ostearius melanopygius in open country suggest that these alien species are gradually colonizing natural biotopes.

Open access

Robert Rozwałka, Tomasz Rutkowski, Wojciech Staręga and Paweł Sienkiewicz

Abstract

The paper presents data on the occurrence of Thanatus atratus in Poland. The long-lasting confusion in Polish and European literature about the existence of 2 similar species T. atratus / T. vulgaris in Poland is clarified. Diagnostic images of T. atratus reproductive organs of both sexes are presented.

Open access

Mariusz Czapliński, Paweł Sokólski, Kazimierz Duzinkiewicz, Robert Piotrowski and Tomasz Rutkowski

Abstract

The pressurizer water level control system in nuclear power plant with pressurized water reactor (PWR) is responsible for coolant mass balance. The main control goal is to stabilize the water level at a reference value and to suppress the effect of time-varying disturbances (e.g. coolant leakage in primary circuit pipeline system). In the process of PWR power plant operation incorrect water level may disturb pressure control or may cause damage to electric heaters which could threaten plant security and stability. In modern reactors standard PID controllers are used to control water level in a pressurizer. This paper describes the performance of state feedback integral controller (SFIC) with reduced-order Luenberger state observer designed for water level control in a pressurizer and compares it to the standard PID controller. All steps from modeling of a pressurizer through control design to implementation and simulation testing in Matlab/Simulink environment are detailed in the paper.

Open access

Robert Rozwałka, Tomasz Rutkowski, Paweł Sienkiewicz and Katarzyna Renn

Abstract

Talavera aperta is a rare member of the Salticidae (jumping spiders). Its presence in Poland has been questioned. This paper presents data on 20 new localities of this poorly known species and a map of its distribution in western and central Poland. Detailed drawings of the male body, male palps and the female epigynum are also provided. T. aperta was usually collected from dry, sunny habitats, mostly in June, although some specimens were recorded in other months. In winter, spiders of this species were found in shells of small snails (Cepaea spp., Helicella obvia).

Open access

Piotr Martyniuk, Małgorzata Kopytko, Paweł Madejczyk, Aleksandra Henig, Kacper Grodecki, Waldemar Gawron and Jarosław Rutkowski

Abstract

The paper reports on a long-wave infrared (cut-off wavelength ~ 9 μm) HgCdTe detector operating under nbiased condition and room temperature (300 K) for both short response time and high detectivity operation. The ptimal structure in terms of the response time and detectivity versus device architecture was shown. The response time of the long-wave (active layer Cd composition, xCd = 0.19) HgCdTe detector for 300 K was calculated at a level of τs ~ 1 ns for zero bias condition, while the detectivity − at a level of D* ~ 109 cmHz1/2/W assuming immersion. It was presented that parameters of the active layer and P+ barrier layer play a critical role in order to reach τs ≤ 1 ns. An extra series resistance related to the processing (RS+ in a range 5−10 Ω) increased the response time more than two times (τs ~ 2.3 ns).

Open access

Artur Pliszko, Grzegorz Łazarski, Paweł Kalinowski, Wojciech Adamowski, Lucjan Rutkowski and Radosław Puchałka

Abstract

In this paper, an updated map of the distribution of Solidago ×niederederi, a natural hybrid between S. canadensis and S. virgaurea, in Poland is presented using the ATPOL cartogram method. A compiled list of 55 localities of the hybrid within 40 cartogram units (10-km squares) is provided and its negative impact on S. virgaurea is highlighted.