Filtry
wszystkich: 6008
wybranych: 5304
wyświetlamy 1000 najlepszych wyników Pomoc
Wyniki wyszukiwania dla: bumble bees
-
Application of the Bodner-Partom constitutive equations for modelling of the technical fabric Valmex used for the hanging roof of the Forest Opera in Sopot
PublikacjaThe study of an inelastic properties of the technical fabric Valmex used for 20 years as the roof structure of the Forest Opera in Sopot (Poland) is presented. The uniaxial tensile laboratory tests with constant strain rate have been conducted and analysed. Parameters of the Bodner-Partom constitutive model have been identified and verified by numerical simulations. Two approaches of the parameters identification have been proposed:...
-
SSFR Test of Synchronous Machine for Different Saturation Levels using Finite-Element Method
PublikacjaIn this paper the StandStill Frequency Response characteristics (SSFR) of saturated synchronous generator (SG) have been calculated using Finite Element Method (FEM) analysis. In order to validate proposed approach for unsaturated conditions FEM simulation from Flux2D software has been compared with the measurements performed on the 10 kVA, 4- poles synchronous machine ELMOR GCe64a of salient rotor construction, equipped with a...
-
Elliptical slot UWB monopole antenna
PublikacjaThe UWB monopole antenna with elliptical radiating slot end and microstrip feeding line terminated with radial stub have been designed, fabricated and measured. The antenna show return loss less than -12 dB in the whole UWB bandwidth. Linearity of the reflection coefficient phase product have also been achieved. Radiation patterns of the antenna measured at three selected frequency points indicated regular, approximately omni directional...
-
Elements of six sigma methodoloygy in polish smes. the pomeranian region context
PublikacjaIn this article, it has been suggested that the effectiveness of the design and implementation of the process approach in the SMEs sector affects the effectiveness and efficiency of the application of elements of the Six Sigma ™ concept. The selected results of the research have been presented to answer the question to what extent small and medium-sized manufacturing, service and production - service companies in Pomeranian region...
-
ASIC Design Example of Complex SoC with FPGA Prototyping
PublikacjaThe paper presents an example of the System on a Chip design, where the FPGA prototyping has been used. Two FPGA prototypes have been realized. The first FPGA prototype uses AVNET board containing Xilinx Virtex4 device accompanied by custom board with required devices. The second FPGA prototype has been built using the custom PCB with Xilinx Virtex-4 XC4VLX60 FPGA accompanied by all needed external components. The final system...
-
Formation of High Corrosion Resistant Nanotubular Layers on TitaniumAlloy Ti13Nb13Zr
PublikacjaThis paper presents results of oxidation tests and corrosion investigations of titanium alloy Ti13Nb13Zr performed at different conditions. The oxide layers have been formed by electrochemical method in 2M H3PO4 + 0.3% HF solution for 30 min. and 1 h at 20 V constantvoltage. The corrosion tests have been made by potentiodynamic method in Ringer`s solution at pH ranged between 3 and 7. It has been shown that the nano-oxide films,...
-
Synthesis and application of oligomer with hydroxy groups based on peroxy derivative of ED-24 epoxy resin and POLYTHF-2000 oligoether
PublikacjaNew oligomer with peroxy, primary and secondary hydroxy groups has been synthesized on the basis of peroxy derivative of ED-24 epoxy resin (PO) and PolyTHF-2000 oligoether according to the developed procedure. The effect of the catalysts nature and amount, temperature and process time on the reaction rate has been studied. Benzyltriethylammonium chloride, potassium hydroxide,1,4-diazobicyclooctane and the mixture composed of benzyltriethylammonium...
-
Formation of High Corrosion Resistant Nanotubular Layers on TitaniumAlloy Ti13Nb13Zr
PublikacjaThis paper presents results of oxidation tests and corrosion investigations of titanium alloy Ti13Nb13Zr performed at different conditions. The oxide layers have been formed by electrochemical method in 2M H3PO4 + 0.3% HF solution for 30 min. and 1 h at 20 V constantvoltage. The corrosion tests have been made by potentiodynamic method in Ringer`s solution at pH ranged between 3 and 7. It has been shown that the nano-oxide films,...
-
Phytoextraction and recovery of rare earth elements using willow (Salix spp.)
PublikacjaSoil and water contaminations are caused by rare earth elements (REEs) due to mining and industrial activities, that threaten the ecosystem and human health. Therefore, phytoremediation methods need to be developed to overcome this problem. To date, little research has been conducted concerning the phytoremediation potential of Salix for REEs. In this study, two Salix species (Salix myrsinifolia and Salix schwerinii) and two Salix...
-
Nonlinear model of a synchronous generator for analysis of more electric aircraft power systems
PublikacjaA nonlinear model for studying a variable-speed synchronous generator (SG) in more electric aircraft (MEA) power system has been developed. The saturation effects of the SG magnetic circuit have been considered. The model has been implemented in the Synopys/Saber simulation environment. The modelling language MAST has been used to elaborate the SG model. The model exhibit a network with the same number of external terminals/ports...
-
Diagnostic testing of marine propulsion systems with internal combustion engines by means of vibration measurement and results analysis
PublikacjaIn this paper selected issues concerning vibration diagnosis of the mechanical system within marine propulsion units have been presented, carried out on the basis of experimental examinations of a real object in which an exceedance of the allowable vibration’s level had been observed. Used diagnosing system has been characterised. A procedure of longitudinal and transverse vibrations shaft lines of the mechanical system within...
-
Nonlinear Model of Synchronous Generator for Autonomous Electrical Power Systems Analysis
PublikacjaThis paper presents the nonlinear lookup table model for synchronous generator (SG) analysis. The saturation effects of the SG magnetic circuit have been considered. The saturated characteristic of the SG magnetic circuit are based on the open circuit saturation curve for magnetizing inductances. The model has been implemented into the Synopsys/Saber software using the MAST modelling language. To implement the no-load voltage characteristic...
-
Targ Węglowy as the keystone of two ring road complexes of Gdańsk city centre
PublikacjaThe urban structure of Gdansk city centre is determined by two ring road complexes. The first of them, the Gdansk Ring, has been created as a result of a city defortification at the turn of the 19th and 20th centuries and has been destroyed in the end of World War Two with the rest of Gdansk. The second, the Main Town Green Belt, has been formed in place of the medieval fortification system of the city’s most important historical...
-
Hybrid DUMBRA: an efficient QoS routing algorithm for networks with DiffServ architecture
PublikacjaDynamic routing is very important issue of current packet networks. It may support the QoS and help utilize available network resources. Unfortunately current routing mechanisms are not sufficient to fully support QoS. Although many research has been done in this area no generic QoS routing algorithm has been proposed that could be used across all network structures. Existing QoS routing algorithms are either dedicated to limited...
-
One-step recovery of REE oxalates in electro-leaching of spent NdFeB magnets
PublikacjaRecovery of rare-earth elements (REEs) from spent NdFeB magnets is receiving great attention because of high amount of neodymium and potential risk of environmental pollution. In this study, a novel environment-friendly hydrometallurgical route is proposed for efficient recovery of REEs during electrochemical leaching with sulfuric and oxalic acids. With proper adjustment of the electrolyte composition and operating conditions,...
-
A Review of Traffic Analysis Attacks and Countermeasures in Mobile Agents' Networks
PublikacjaFor traditional, message-based communication, traffic analysis has been already studied for over three decades and during that time various attacks have been recognised. As far as mobile agents’ networks are concerned only a few, specific-scope studies have been conducted. This leaves a gap that needs to be addressed as nowadays, in the era of Big Data, the Internet of Things, Smart Infrastructures and growing concerns for privacy,...
-
Approaches to Static Digestion Models
PublikacjaIt is not possible to look in detail at the wide range of static digestion methods that have been used to date. However, this section looks at some of the general approaches that have been used to look at the digestion of various nutrients and bioactives. I have focussed on the two main nutrients that undergo digestion in the upper GI tract, namely protein and lipid. In the case of protein, the research has largely been driven...
-
Structure and thermoelectric properties of Bi–Te alloys obtained by novel method of oxide substrates reduction
PublikacjaA novel method of thermoelectric materials fabrication has been developed. Oxide reagents have been melted at high temperature in air, quenched, milled to powder and reduced in hydrogen to form Bi–Te alloys. Structural and thermoelectric properties of samples have been investigated depending on initial composition and temperature of reduction process. Sample 25Bi2O3–75TeO2 reduced at 340 °C for 10 h has been found to be a p-type...
-
Signal filtering method of the fast-varying diesel exhaust gas temperature
PublikacjaThe paper presents the problem of the impact of external distortions originating on laboratory test stands on the results of measurements of fast-varying diesel exhaust gas temperature. It has been stressed how significant the aspect of the test stand adaptation is during an experiment to ensure the smallest possible impact. This paper, however, focuses on the methods of mathematical processing of a signal recorded during experimental...
-
The Role of a Software Product Manager in Various Business Environments
PublikacjaThe aim of the paper is to identify the role of the software product manager depending on the size of the company and the characteristics of the product they are working on. This has been achieved in cooperation with 15 experts from the IT industry. The companies were divided into 4 levels of size: micro-enterprises, small businesses, medium businesses and large enterprises. The characteristics of the products were divided into...
-
Superconductivity and itinerant ferromagnetism of Y9Co7 probed by ac susceptibility
PublikacjaThe ac magnetic susceptibility of a single crystal sample of the compound Y9Co7 has been measured in applied dc fields ranging from 0–6.7 kOe by utilizing a tunnel diode resonator circuit. In agreement with previous measurements on this material, a superconducting transition has been observed to occur at TSC ≈ 2.5 K. A broad maximum has been observed in the zero field susceptibility measurements from 2.5 K < T < 8 K and its behavior...
-
Angle Tracking Observer for Filtering Rotor Position Estimates in Sensorless Electric Drives
PublikacjaSensorless electric drives use measurements of electrical quantities to estimate rotor position and speed. Measurement errors deteriorate the estimation accuracy, thus additional means are necessary to remove high-frequency components from estimated signals. This paper proposes to use an Angle Tracking Observer (ATO) for reducing noise in rotor position estimates, which is related to random errors in the measurements. A simplified,...
-
Behaviour of Colliding Multi-Storey Buildings under Earthquake Excitation Considering Soil-Structure Interaction
PublikacjaThis paper investigates the coupled effect of the supporting soil flexibility and pounding between neighbouring, insufficiently separated buildings under earthquake excitation. Two adjacent three-storey structures, modelled as inelastic lumped mass systems with different structural characteristics, have been considered in the study. The models have been excited using the time history of the Kobe earthquake of 1995. A nonlinear...
-
Effect of the ionic liquids on extraction of aromatic and sulfur compounds from the model petrochemical stream
PublikacjaSuitability of a imidazolium ionic liquids (ILs) as solvents in dearomatization and desulfurization in the ternary systems and in a model multicomponent systems has been analyzed. With this aim, ternary liquid-liquid phase equilibrium data (LLE) have been obtained for ternary mixtures of {IL + benzene, or toluene, or thiophene, or 2-butanethiol + hexane}, or {IL + benzene + 2-methylpentane} at T = 298.15 K and ambient pressure,...
-
Influence of service ageing on polyester-reinforced polyvinyl chloride-coated fabrics reported through mathematical material models
PublikacjaIn this paper the coupled service (constructional tension) and environmental (sunlight, rainfalls, temperature variations) ageing influence on the polyester-reinforced polyvinyl chloride (PVC)-coated fabric VALMEX is studied. Two cases of the same fabric have been analyzed: one USED for 20 years on the real construction of the Forest Opera in Sopot (Poland), and one kept as a spare material (NOT USED). The following tests have...
-
Downlink Capacity-Coverage Trade-off Estimation Based on Measurement of WCDMA/FDD Interface Load
PublikacjaThe method of capacity-coverage trade-off determination by using of universal load characteristics and normalized coverage curves for the WCDMA/FDD radio interface has been presented. The practical applications of discussed method for UMTS radio network planning process and network exploitation has been mentioned.
-
A compact seven-section rat-race hybrid coupler incorporating pbg cells
PublikacjaA conventional rat-race coupler has been doubly miniaturized: (i) characteristic impedances and electrical lengths of microstrip sections have been adequately modified as the first step of size reduction and (ii) T-shaped PBG cells have been implemented to diminish strip section length as the second step of circuit rat-race couplerminiaturization. The experimental results show good agreement with theoretical characteristics. Furthermore,...
-
Third harmonic index as a diagnostic tool of high-voltage varistors
PublikacjaThe recommended methods for standard testing of high-voltage varistors demand application of high voltages and intensive currents that is inconvenient and needs extensive power consumption. These methods require metallization of the prepared ZnO structures that increases costs of testing. Another method of varistor quality and endurance evaluation by the third harmonic index measurement at relatively low voltage range has been...
-
Slow-wave resonant structures in branch-line coupler miniaturization: a case study
PublikacjaA case study of novel slow-wave resonant structures dedicated to efficient microstrip branch-line coupler size reduction has been presented. A compact 3-dB branch-line coupler has been designed to mimic the performance of its conventional counterpart, simultaneously demonstrating a substantial 88% surface area reduction. The vital usefulness of the approach in the process of microstrip line abbreviation has been experimentally...
-
Slow-wave fractal-shaped compact microstrip resonant cell
PublikacjaA novel fractal-shaped compact microstrip resonant cell (CMRC) featuring a strong slow-wave effect has been presented. Its vital usefulness in the process of microstrip line miniaturisation has been proved and experimentally validated on the basis of a compact 3-dB branch-line coupler illustrating the possibilities of the approach. A prototype example structure has been designed to mirror the characteristics of a conventional device,...
-
Diagnosis of bearing damage in induction motors by instantaneous power analysis
PublikacjaResearch of the machine with simulated bearing damages has been carried out, where variable load torque, simulating bearing damage, was introduced. The results show that components which can be used for bearings diagnosis appear in the spectrum of the product of current and supply voltage instantaneous values. These components are easier to identify than the components of current spectrum, which have been used so far in diagnostic...
-
Wpływ procesu redukcji na właściwości strukturalne i mechaniczne szkieł tlenkowych z grupy (Pb,Bi)-(Si,Ge)-O = Influence of reduction process on the structural and mechanical properties of (Pb,Bi)-(Si,Ge)-O oxide glasses
PublikacjaThe effect of the reduction process in H2 at 380 °C on the microstructure and elemental composition of a glass Bi0.4Pb0.2Si0.4Ox has been investigated. It has been shown that after reduction a clearly separated top layer with a thickness of approx. 50 µm was formed on the surface of the sample. This layer is depleted of oxygen and has higher electrical conductivity than the interior of the glass. It has also been found that some...
-
Apparent molar volumes and compressibilities of alkaline earth metal ions in methanol and dimethylsulfoxide
PublikacjaTemperature dependencies of density of magnesium (II), calcium (II), strontium (II), barium (II) perchlorates as well as beryllium (II), and sodium trifluoromethanesulfonates in methanol and dimethylsulfoxide have been determined over the composition range studied. From density data the apparent molar volumes and partial molar volumes of the salts at infinite dilution as well as the expansibilities have been evaluated. The apparent...
-
Influence of reduction process on the structural and mechanical properties of (Pb,Bi)-(Si,Ge)-O oxide glasses
PublikacjaThe effect of the reduction process in H2 at 380 °C on the microstructure and elemental composition of a glass Bi0.4Pb0.2Si0.4Ox has been investigated. It has been shown that after reduction a clearly separated top layer with a thickness of approx. 50 µm was formed on the surface of the sample. This layer is depleted of oxygen and has higher electrical conductivity than the interior of the glass. It has also been found that some...
-
Five-phase squirrel-cage motor. Construction and drive properties
PublikacjaThis paper presents the simulation and experimental results of a five-phase squirrel-cage induction motor. The new machine has been designed to operate in a drive system with third harmonic rotor flux injection in order to improve the motor torque utilization. The motor structure, the mathematical model as well as the laboratory prototype have been described. The motor speed-torque characteristics and transients are elaborated...
-
Comparison of the tests for equivalence of the measurement methods for measurement of PM10 dust in ambient air
PublikacjaThe paper presents the motives for conducting the equivalence tests and the reasons of discrepancies between the results of PM10 dust concentration obtained via the reference method and the methods based on 'on-site' measurement. The reference and non-reference methods of measurement of PM10 dust concentration in air have been discussed. Field tests for equivalence, following the Polish standard and the European Union (EU) guidelines,...
-
Total cross section measurements for electron scattering from tin(IV) chloride (SnCl4)
PublikacjaTotal cross section for electron scattering from SnCl4 molecules has been measured for energies from 0.6 to 300 eV. Obtained results have been compared with total cross sections for electron scattering from other tetrachloride molecules: XCl4 where X=C, Si, Ge.
-
Study on deformed steel columns subjected to impact load due to soft-storey failure in buildings during earthquakes
PublikacjaThe so called soft-storey failure is one of the most typical types of damage induced in buildings as the result of earthquake excitation. It has been observed during ground motions that the failure of an upper soft storey of a structure results in large vertical impact load acting on the lower floors. If the resistance of the structural members of the lower storeys is not sufficient it may further lead to progressive collapse of...
-
Mathematical model to assess energy consumption using water inflow-drainage system of iron-ore mines in terms of a stochastic process
PublikacjaPurpose is to develop a unified mathematical model to assess energy efficiency of a water inflow-drainage process as the real variant of stochastic method for water pumping from underground workings of iron-ore mines. Methods. The research process was based upon the methods of probability theory as well as stochastic modelling methods. The stochastic function integration has been reduced to summation of its ordinates and further...
-
Two-body dissociation of isoxazole following double photoionization – an experimental PEPIPICO and theoretical DFT and MP2 study
PublikacjaThe dissociative double photoionization of isoxazole molecules has been investigated experimentally and theoretically. The experiment has been carried out in the 27.5–36 eV photon energy range using vacuum ultraviolet (VUV) synchrotron radiation excitation combined with ion time-of-flight (TOF) spectrometry and photoelectron–photoion–photoion coincidence (PEPIPICO) technique. Five wellresolved two-body dissociation channels have...
-
Historical carpentry corner log joints—Numerical analysis within stochastic framework
PublikacjaThe paper presents the results of numerical analysis performed on historical, traditional carpentry corner logjoints of two basic topologies: the short-corner dovetail connection and the saddle notch connection. These types of carpentry joints are commonly used in currently preserved objects of wooden architecture. All connections have been modelled in pinewood, which has been defined in the Finite Element software MSC.Marc/Mentat...
-
Operation evaluation method for marine turbine combustion engines in terms of energetics
PublikacjaAn evaluation proposal (quantitative determination) of an y combustion turbine engine operation has been presented , wherein the impact energy occurs at a given time due to Energy conversion. The fact has been taken into account that in this type of internal combustion engines the energy conversion occurs first in the combustion chambers and in the spaces between the blade of the turbine engine. It was assumed that in the combustion...
-
Comparison of various flow maldistribution quantification methods in mini heat exchangers
PublikacjaThe aim of study is to compare various flow maldistribution quantification methods, using velocity, mass flow rate, pressure, and temperature. An experimentally validated numerical study has been prepared and a heat exchanger with 34 semi-circular channels with a diameter of 3.1 mm has been tested. The minichannels were heated from the bottom with a heat flux of 50, 60, 70, and 80 kW/m2. The cases for various inlet velocities of...
-
The importance of anchoring ligands of binuclear sensitizers on electron transfer processes and photovoltaic action in dye-sensitized solar cells
PublikacjaThe relatively low photon-to-current conversion efficiency of dye-sensitized solar cells is their major drawback limiting widespread application. Light harvesting, followed by a series of electron transfer processes, is the critical step in photocurrent generation. An in-depth understanding and fine optimization of those processes are crucial to enhance cell performance. In this work, we synthesize two new bi-ruthenium sensitizers...
-
An analysis of wind conditions at pedestrian level in the selected types of multi-family housing developments
PublikacjaThe following article addresses the issue of wind conditions around urban building development at pedestrian level. Factors that depend on those issues include wind comfort and air quality within urbanized spaces. The conditions specific of cities located in a temperate climate zone have been taken into account. The article is intended to identify aerodynamic phenomena characteristic of the three basic types of multi-family building...
-
Solid phase microextraction: state of the art, opportunities and applications
PublikacjaSolid phase microextraction is one of the most popular green techniques used for sample preparations in analytical chemistry. It is a simple, rapid, sensitive, and solvent-free technique. Since SPME was first introduced in the early 1990s, there has been an intensification of research in order to elaborate new methodical solutions in many research facilities around the world, which could increase the use of this technique. More...
-
Experimental research on technical fabric of the Forest Opera Roof in Sopot
PublikacjaThe experimental analysis of the technical fabric Valmex is presented. The study involves uniaxial tensile, cyclic, rheological and biaxial tests. Some of the main differencies between two types of the analysed material have been identified. Mechanical properties of the textile have been modeled by the viscoelastic standard model with quite good effect.
-
Electroelastic biaxial compression of nanoplates considering piezoelectric effects
PublikacjaIn the present theoretical work, it is assumed that a piezoelectric nanoplate is connected to the voltage meter which voltages have resulted from deformation of the plate due to in-plane compressive forces whether they are critical buckling loads or arbitrary forces. In order to derive governing equations, a simplified four-variable shear deformation plate theory has been employed using Hamilton’s principle and Von-Kármán...
-
Towards β-selectivity in functional estrogen receptor antagonists
PublikacjaBased on the benzo[b]naphtho[1,2-d]furan and benzo[b]naphtho[1,2-d]thiophene frameworks, a series of ligands with different basic side chains (BSCs) has been synthesized and pharmacologically evaluated. Also, their binding modes have been modelled using docking techniques. It was found that the introduction of a BSC in these systems brings about a decrease of affinity for both estrogen receptors α and β in an in vitro competitive...
-
Investigation of catalytic layers on anode for solid oxide fuel cells operating with synthetic biogas
PublikacjaIn this paper solid oxide fuel cells operating with dry synthetic biogas have been examined. In order to increase their stability the layers of CuO-CeO2, Cu1.3Mn1.7O4 and Y0.08Sr0.92Ti0.8Fe0.2O3 -δ have been deposited on the Ni-YSZ anode site. These layers should catalyze the internal biogas reforming and prevent the carbon deposition on the anode site. It has been found that CuO-CeO2 and Cu1.3Mn1.7O4 catalysts led to an increase...