2017 - Repozytorium publikacji - Politechnika Gdańska

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Examining Feature Vector for Phoneme Recognition / Analiza parametrów w kontekście automatycznej klasyfikacji fonemów
- Grazina Korvel
- Bożena Kostek
2017
The aim of this paper is to analyze usability of descriptors coming from music information retrieval to the phoneme analysis. The case study presented consists in several steps. First, a short overview of parameters utilized in speech analysis is given. Then, a set of time and frequency domain-based parameters is selected and discussed in the context of stop consonant acoustical characteristics. A toolbox created for this purpose in the Matlab environment is presented. The next analysis step includes the process of selecting the most discriminating descriptors based on Bron Kerbosch algorithm. It is shown that parameters resulted from this analysis can be used for separation of consonants. Finally, phoneme recognition is performed employing k-NN classifier.
Excess molar volume and viscosity deviation for binary mixtures of gamma-butyrolactone with dimethyl sulfoxide
- Joanna Krakowiak
- Maciej Śmiechowski
2017 JOURNAL OF CHEMICAL THERMODYNAMICS
The densities of binary liquid mixtures of dimethyl sulfoxide and gamma-butyrolactone at (293.15, 298.15, 303.15 and 313.15) K and viscosity at T=298.15 K have been measured at atmospheric pressure over theentire range of concentration. From these data the excess molar volumes VE at (293.15, 298.15, 303.15 and 313.15) K and the viscosity deviation, the excess entropy, and the excess Gibbs energy of activation for viscous flow at T=298.15 K have been determined. These data were mathematically represented by the Redlich-Kister polynomial. Partial and apparent molar volumes have been calculated for better understanding of the interactions in the binary systems. The obtained data indicate the lack of specific interactions between unlike molecules, which seem to be a little weaker as compared to the interactions in pure solvents.
EXCHANGE TRADED COMMODITIES AS A CATEGORY OF INNOVATIVE PRODUCTS ON EUROPEAN FINANCIAL MARKETS
- Adam Marszk
2017 Pełny tekst Financial Internet Quarterly
The article presents the main features of one category of innovative financial products – exchange traded commodities (ETCs) and results of the analysis of the European market for ETCs. ETCs are products listed and traded on the stock exchanges and they offer investors returns based on various assets (commodities or currencies). In contrast with the most widely recognized exchange traded funds (ETFs), ETCs are structured as debt instruments due to legal requirements regarding investment funds in the European Union. The European ETCs market is the largest in the world (in terms of assets its share in the global market in 2015 was close to 98%). It had developed rapidly until 2012 when total assets reached the record-high value of ca. 26,6 billion EUR (i.e. 9,5% of total assets of all exchange traded products listed in Europe). Over the next few years both the value of assets and market share of ETCs decreased significantly, mostly due to decline of the tracked assets’ prices (especially commodities) – during the analyzed time periodthe average flows to commodity or currency ETCs were close to 0.
Expedited EM-Driven Design of Miniaturized Microwave Hybrid Couplers Using Surrogate-Based Optimization
- Piotr Kurgan
2017 Pełny tekst
Miniaturization of microwave hybrid couplers is important for contemporary wireless communication engineering. Using standard computer-aided design methods for development of compact structures is extremely challenging due to a general lack of computationally efficient and accurate simulation models. Poor accuracy of available equivalent circuits results from neglecting parasitic cross-couplings that greatly affect the performance of miniaturized devices. On the other hand, electromagnetic (EM) simulations may be very accurate, but at the same time they are extremely CPU-heavy and time consuming. The methodologies included in this dissertation address the problem of reliable and computationally efficient design of miniaturized hybrid couplers. The proposed methods are based on a generic SBO scheme and employ a number of customized techniques for development of fast and accurate surrogates. These techniques include decomposition, equivalent circuits, EM modeling, response surface approximations, and space mapping. The presented numerical results, confirmed also experimentally, indicate a dramatic reduction in the computational cost of the discussed methods (on average, 25 times speedup in comparison to direct EM optimization). A suite of novel hybrid couplers obtained in this work demonstrate outstanding miniaturization ratios ranging between 82% and 94% with good transmission characteristics. To the best of author’s knowledge, the developed methods are the only procedures so far in the literature that allow for obtaining high-performance EM-validated design solutions of miniaturized hybrid couplers at a low computational cost.
Expedited Metaheuristic-Based Antenna Optimization Using EM Model Resolution Management
- Anna Pietrenko-Dąbrowska
- Sławomir Kozieł
- Leifur Leifsson
2017
Design of modern antenna systems heavily relies on numerical opti-mization methods. Their primary purpose is performance improvement by tun-ing of geometry and material parameters of the antenna under study. For relia-bility, the process has to be conducted using full-wave electromagnetic (EM) simulation models, which are associated with sizable computational expendi-tures. The problem is aggravated in the case of global optimization, typically carried out using nature-inspired algorithms. To reduce the CPU cost, popula-tion-based routines are often combined with surrogate modeling techniques, frequently in the form of machine learning procedures. While offering certain advantages, their efficiency is worsened by the curse of dimensionality and antenna response nonlinearity. In this article, we investigate computational ad-vantages of combining population-based optimization with variable-resolution EM models. Consequently, a model management scheme is developed, which adjusts the discretization level of the antenna under optimization within the continuous spectrum of acceptable fidelities. Starting from the lowest practically useful fidelity, the resolution converges to the highest assumed level when the search process is close to conclusion. Several adjustment profiles are considered to investigate the speedup-reliability trade-offs. Numerical results have been obtained for two microstrip antennas and particle swarm optimizer as a widely-used nature-inspired algorithm. Consistent acceleration of up to eighty percent has been obtained in comparison to the single-resolution version with minor deterioration of the design quality. Another attractive feature of our methodology is versatility and easy implementation and handling.
Expedited simulation-driven design optimization of UWB antennas by means of response features
- Sławomir Kozieł
- Adrian Bekasiewicz
2017 Pełny tekst INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING
In this work, a method for fast design optimization of broadband antennas is considered. The approach is based on a feature-based optimization (FBO) concept where reflection characteristics of the structure at hand are formulated in terms of suitably defined feature points. Redefinition of the design problem allows for reducing the design optimization cost, because the dependence of feature point coordinates on antenna dimensions is less nonlinear than for the original frequency characteristics (here, S-parameters). This results in faster convergence of the optimization algorithm. The cost of the design process is further reduced using variable-fidelity electromagnetic (EM) simulation models. In case of UWB antennas, the feature points are defined, among others, as the levels of the reflection characteristic at its local in-band maxima, as well as location of the frequency point which corresponds to acceptable reflection around the lower corner frequency within the UWB band. Also, the number of characteristic points depends on antenna topology and its dimensions. Performance of FBO-based design optimization is demonstrated using two examples of planar UWB antennas. Moreover, the computational cost of the approach is compared to conventional optimization driven by a pattern search algorithm. Experimental validation of the numerical results is also provided.
Experience-Oriented Intelligence for Internet of Things
- Haoxi Zhang
- Fei Li
- Juan Wang
- Cesar Sanín
- Edward Szczerbicki
2017 Pełny tekst CYBERNETICS AND SYSTEMS
The Internet of Things (IoT) has gained significant attention from industry as well as academia during the past decade. The main reason behind this interest is the capabilities of the IoT for seamlessly integrating classical networks and networked objects, and hence allows people to create an intelligent environment based on this powerful integration. However, how to extract useful information from data produced by IoT and facilitate standard knowledge sharing amongst different IoT systems, are still open issues to be addressed. In this paper, we propose a novel approach, the Experience-Oriented Smart Things (EOST), that utilizes deep learning and knowledge representation concept called Decisional DNA to help IoT systems acquire, represent, and store knowledge, as well as share it amid various domains where it can be required to support decisions. We demonstrate our approach in a set of experiments, in which the IoT systems use knowledge gained from past experience to make decisions and predictions. The presented initial results show that the EOST is a very promising approach for knowledge capture, representation, sharing, and reusing in IoT systems.
Experiencing historic waterways and water landscapes of the Vistula River Delta
- Lucyna Nyka
2017
The paper gives insights into the characteristics of Vistula River Delta water landscapes, referring to the process of creating land out of water by Polish, Dutch and German settlers. Based on this, the paper presents an integrated strategy formed upon studies in cultural geography and aesthetics, and focused on enhancing the unique characteristics of the region and its rediscovery by tourism. The long process of constructing Vistula River Delta landscape out of water, marshlands and alluvial deposits resulted in creating a unique polder territory structured by canals, dikes, systems of water locks and bridges. Patterns of canals and surrounding landscapes changed in time along with the development of hydro-engineering constructions, leading to the emergence of a unique cultural identity. After decades of negligence the Vistula River Delta landscape is currently being re-appreciated. New challenges arise, however, imposing questions on possible strategies for sustainable tourism that will lead to the discovery of historical waterways and their related landscapes in their natural-cultural unity, and not only provide visitors with knowledge about the region but also with the direct experience of this water–dependant territory. Developing a water-connections strategy by means of rivers and historic canals allows people to stay directly on water, participate with its rhythms and flows, and get insights into the unique topography negotiated between land and water. It will not only stimulate tourism but also contribute to the better appreciation of the heritage understood as a consequent continuous process of negotiating the boundaries between the river and inhabitable space – nature and architecture.
Experimental and numerical analysis of an aluminum cantilevered beam with polymer adhesive
- Natalia Lasowicz
- Robert Jankowski
2017 Pełny tekst Procedia Engineering
In this paper, experimental and numerical investigation on a composite cantilevered aluminum beam has been conducted. The subject of the study consists of two plain aluminum elements bonded with polymer adhesive of different thickness. It has been proven in the previous study that this kind of material has high damping properties. During an experimental investigation, value of damping ratios have been obtained. The aim of a numerical analysis was to determine dynamic parameters, such as modes of free vibration and corresponding natural frequencies. The results obtained from the analysis have been compared with the values estimated for plain cantilevered beam. The results of the study clearly show that bonding two stiff elements with the analyzed polymer adhesive leads to the significant increase in overall damping properties.
Experimental and numerical assessment of size effect in geometrically similar slender concrete beams with basalt reinforcement
- Ewelina Korol
- Andrzej Tejchman-Konarzewski
- Zenon Mróz
2017 ENGINEERING STRUCTURES
W artykule przedstawiono doświadczalne i numeryczne wyniki badań efektu skali w geometrycznie podobnych smukłych belkach betonowych ze zbrojeniem bazaltowym. Doświadczenia zostały symulowane stosując metodę elementów skończonych w oparciu o model sprężysto-plastyczny z degradacją sztywności i nielokalnym osłabieniem. Otrzymano dobrą zgodność wyników doświadczalnych z numerycznymi.
EXPERIMENTAL AND NUMERICAL INVESTIGATIONS OF CONCRETE BEHAVIOUR AT MESO-LEVEL DURING QUASI-STATIC SPLITTING TENSION
- Jan Suchorzewski
- Andrzej Tejchman-Konarzewski
2017 Pełny tekst
The paper describes experimental and numerical results of quasi-static splitting tensile tests on concrete specimens at meso-scale level. The loading strip was made of plywood or steel. Fracture in concrete was detected at the aggregate level by means of three non-destructive methods: 3D x-ray micro-computed tomography, 2D scanning electron microscope and manual 2D digital microscope. The discrete element method was used to directly simulate experiments at the meso-scale. Concrete was modelled as a random heterogeneous 4-phase material composed of aggregate particles, cement matrix, interfacial transitional zones and macro-voids based on micro-tomographic images. Two-dimensional calculations with real concrete microstructure were carried out. A satisfactory agreement between numerical and experimental results was achieved. The evolution of contact normal forces, coordination number, broken contacts, grain rotations and crack displacements was also investigated. In addition, each energy component was calculated and analyzed at a different stress-displacement stage.
Experimental evaluation of estimator mean square error curve for cognitive tracking radar
- Michał Meller
2017 Pełny tekst
To make decisions, cognitive radar must rely on predictions of its own performance. In the literature, these predictions are usually based on some form of Cram\'er-Rao lower bound. This approach is scientifically sound, but it also brings a possibility of the cognitive controller overestimating radar performance. It therefore makes sense to back theoretical predictions with careful experiments which will verify their applicability. Using a simple direction of arrival estimator as an example we discuss how an experimental performance curve can be obtained. We also propose an extended approach, which employs experimental data to estimate parameters of a performance curve which includes floor and threshold effects.
Experimental investigations on adiabatic frictional pressure drops of R134a during flow in 5mm diameter channel
- Rafał Andrzejczyk
- Tomasz Muszyński
- Carlos Alberto Dorao
2017 EXPERIMENTAL THERMAL AND FLUID SCIENCE
The article presents detailed two-phase adiabatic pressure drops data for refrigerant R134a at a saturation pressure of 5.5 bar corresponding to the saturation temperature of 19.4 °C. Study cases have been set for a mass flux varying from 100 to 500 kg/m2 s. The frictional pressure drop was characterized for the refrigerant R134a, for vapor qualities ranging from 0 to 1. Long-time thermal stability of test facility allowed to gather a comprehensive experimental database for two-phase frictional pressure drop including multiple data points in transition and dryout flow regions. The effect of transition region on the peak value of two-phase frictional pressure drop, for literature models and experiment, is recognized. A systematic assessment of predictive techniques for two-phase frictional pressure drop in adiabatic flows for varying vapor quality was conducted. Both qualitative and quantitative analysis of gathered data vs. literature models was presented. Verification of the pressure drop for two-phase adiabatic flow showed that for Zhang and Webb correlation 93% of experimental data fits in the range of ±30%. The model proposed by Thome et al. in other hand predicts almost 33% of data within 10% error, but only 80% of the data is predicted within 30% error. Additional prediction of the peak value of two-phase frictional pressure drop with literature models and the experiment was made.
Experimental study of pressure rise at the evaporator of capillary pumped loop with acetone and water as working fluids
- Paweł Szymański
- Dariusz Mikielewicz
2017 Pełny tekst EXPERIMENTAL THERMAL AND FLUID SCIENCE
In this work studied is the possibility of fluid pumping using capillary forces in the capillary pumped loop. Experimental and theoretical studies have been performed to understand the phenomena associated with heat transfer in porous structure of the evaporator. The capillary effect was studied during operation of two different capillary porous structures with two different working fluids, namely water and acetone. The results gave a foundation for a new concept of modern evaporator for waste heat recovery that supports the fluid pumping in the thermodynamic cycle. The results shows that evaporator filled by capillary wick made of Ni-Cu sintered porous material can produce the pressure difference up to 1.63 kPa at theheat rate input of 100 W.
Experimental Study on Effectiveness of a Prototype Seismic Isolation System Made of Polymeric Bearings
- Tomasz Falborski
- Robert Jankowski
2017 Pełny tekst Applied Sciences-Basel
Seismic isolation is identified as one of the most popular and effective methods of protecting structures under strong dynamic excitations. Base isolators, such as Lead Rubber Bearings, High Damping Rubber Bearings, and Friction Pendulum Bearings, are widely used in practice in many earthquake-prone regions of the world to mitigate structural vibrations, and therefore minimize loss of life and property damage during seismic events. The present paper reports the results of the comprehensive experimental investigation designed to verify the effectiveness of a prototype base isolation system made of Polymeric Bearings in reducing structural vibrations. In order to construct seismic bearings considered in this study, a specially prepared polymeric material with improved damping properties was used. The dynamic behaviour of a single-storey and two-storey experimental model, both fixed-base and base-isolated, under a number of different ground motions, was extensively studied. The reduction in lateral response was measured by comparing the peak accelerations recorded at the top of the analyzed model structures with and without a base isolation system. The results of this research clearly demonstrate that the application of the prototype Polymeric Bearings leads to significant improvement in seismic response by reducing the lateral acceleration.
Experimental Testbed of ASON/GMPLS architecture
- Kamil Bławat
- Sylwester Kaczmarek
- Magdalena Młynarczuk
2017 Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne
The paper presents the ASON/GMPLS architecture realized in the Department of Teleinformation Networks at Gdansk University of Technology based on the FSP 3000R7 ADVA Optical Networking platform. The FSP 3000R7 is a high-performance WDM networking system with GMPLS control plane for bidirectional transmission of optical signals. The system uses a modular structure which enables a flexible upgrade of capacity and functionality. The authors have made an effort to implement ASON/GMPLS architecture based on Fiber Service Platform with GMPLS control plane (FSP 3000R7). The ASON/GMPLS architecture is realized according to actual standards and recommendation. In the paper ASON/GMPLS architecture, Fiber Service Platform with GMPLS control plane and ASON/GMPLS implementation of laboratory testbed are presented. The details of implementation are briefly described. Moreover functional test results are presented.
EXPERIMENTAL VERIFICATION OF THE METHOD OF FLOW BOILING AND FLOW CONDENSATION HEAT TRANSFER PREDICTION FOR SELECTED FLUIDS
- Dariusz Mikielewicz
- Blanka Jakubowska
2017
In the paper presented are the results of calculations using authors own model to predict heat transfer coefficient during flow boiling of different refrigerants. The experimental data from various research studies from literature were collected. Calculations were conducted for a full range of quality variation and a wide range of mass velocity. The aim of the study was to test the sensitivity of the in- house developed model. The results show the importance of taking into account the surface tension as the parameter exhibiting its importance in case of the flow in minichannels as well as the influence of reduced pressure. The calculations of the two-phase multiplier have been made taking into account the non-adiabatic effects in bubbly and annular flow cases.
Experiments and numerical analyses for composite RC-EPS slabs
- Łukasz Skarżyński
- Ireneusz Marzec
- Andrzej Tejchman-Konarzewski
2017 Computers and Concrete
W artykule przedstawiono wyniki doświadczalne i numeryczne dla kompozytowych płyt złożonych z żelbetu i styropianu. Wykonano doświadczenia dla płyt w skali 1:1 podczas zginania. Wyniki doświadczalne zostały modelowane stosując 2 różne modele: sprężysto-plastyczny i połączony sprężysto-plastyczny z degradacja sztywności. Oba model zostały wyposażone w długość charakterystyczna mikrostruktury. Osiągnięto dobra zgodność miedzy wynikami doświadczalnymi i numerycznymi.
Extended duration running and impulse loading characteristics of an acoustic bearing with enhanced geometry
- Tadeusz Stolarski
- Rafał Gawarkiewicz
- Krzysztof Tesch
2017 TRIBOLOGY LETTERS
This paper presents performance during prolonged running of the acoustic bearing when PZTs are switched off and when they are switched on. The effect of active PZT on shaft’s displacements in X and Y directions is clearly demonstrated. Performance of the acoustic bearing was also assessed when an impulse force was applied to the running shaft at speed. Once again the benefits of having PZTs active are beyond doubt. The instability caused by the impulse force was rapidly mitigated as the bearing returned to its usual dynamics within around two second. In contrast, dynamics of the acoustic bearing operating with PZTs switched off was significantly disturbed and in the time of the test never returned to its status before application of the impulse force.
Extending Expressiveness of Knowledge Description with Contextual Approach
- Aleksander Waloszek
- Wojciech Waloszek
2017
In the paper we show how imposing the contextual structure of a knowledge base can lead to extending its expressiveness without changing the underlying language. We show this using the example of Description Logics, which constitutes a base for a range of dialects for expressing knowledge in ontologies (including state-of-the-art OWL). While the contextual frameworks have been used in knowledge bases, they have been perceived as a tool for merging different viewpoints and domains, or a tool for simplifying reasoning by constraining the range of the statements being considered. We show, how it may also be used as a way of expressing more complicated interrelationships between terms, and discuss the import of this fact for authoring ontologies.