2018 - Repozytorium publikacji - Politechnika Gdańska

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A constitutive law for concrete with smooth transition from continuous into discontinuous cracks’ description
- Jerzy Bobiński
- Andrzej Tejchman-Konarzewski
2018
Paper presents a constitutive model for concrete that combines a continuous and discontinuous crack’s description to simulate the concrete under tensile dominated loads. In a continuum regime, two different constitutive laws were used. First, a plasticity model with the Rankine failure criterion and an associated flow rule was used. Second, a constitutive law based on isotropic damage mechanics was formulated. Both model alternatives were enriched by a characteristic length of micro-structure with the aid of a integral non-local theory to preserve the mesh-insensitivity of FE-results. Displacement jumps across cracks were captured by applying the eXtended Finite Element Method (XFEM) with cohesive tractions. A transfer function was introduced allowing for a gradual switch from a continuous (smeared) to discontinuous (discrete) softening process. Nodes and elements in the transition zone were doubled. Two benchmarks were numerically simulated with a dominated mode-I (three-point bending test) and under mixed-mode conditions (Nooru-Mohamed test).
A Data Driven Model for Predicting RNA-Protein Interactions based on Gradient Boosting Machine
- Dharm Skandh Jain
- Sanket Rajan Gupte
- Raviprasad Aduri
2018 Pełny tekst Scientific Reports
RNA protein interactions (RPI) play a pivotal role in the regulation of various biological processes. Experimental validation of RPI has been time-consuming, paving the way for computational prediction methods. The major limiting factor of these methods has been the accuracy and confidence of the predictions, and our in-house experiments show that they fail to accurately predict RPI involving short RNA sequences such as TERRA RNA. Here, we present a data-driven model for RPI prediction using a gradient boosting classifier. Amino acids and nucleotides are classified based on the high-resolution structural data of RNA protein complexes. The minimum structural unit consisting of five residues is used as the descriptor. Comparative analysis of existing methods shows the consistently higher performance of our method irrespective of the length of RNA present in the RPI. The method has been successfully applied to map RPI networks involving both long noncoding RNA as well as TERRA RNA. The method is also shown to successfully predict RNA and protein hubs present in RPI networks of four different organisms. The robustness of this method will provide a way for predicting RPI networks of yet unknown interactions for both long noncoding RNA and microRNA.
A Device for Measuring Auditory Brainstem Responses to Audio
- Piotr Odya
- Andrzej Czyżewski
- Andrzej Sroczyński
- Bożena Kostek
2018 Pełny tekst
Standard ABR devices use clicks and tone bursts to assess subjects’ hearing in an objective way. A new device was developed that extends the functionality of a standard ABR audiometer by collecting and analyzing auditory brainstem responses (ABR). The developed accessory allows for the use of complex sounds (e.g., speech or music excerpts) as stimuli. Therefore, it is possible to find out how efficiently different types of sounds are processed in the hearing system including brain. The paper contains technical details related to the design of the device, including its hardware and software parts. The test results that have been carried out to verify the operation of the device are also described.
A Family of Pb-based Superconductors with Variable Cubic to Hexagonal Packing
- Tai Kong
- Karolina Górnicka
- Sylwia Gołąb
- Bartlomiej Wiendlocha
- Tomasz Klimczuk
- Robert J. Cava
2018 JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
We describe three previously unreported superconductors, BaPb3, Ba0.89Sr0.11Pb3, and Ba0.5Sr0.5Pb3. These three materials, together with SrPb3, form a distinctive isoelectronic family of intermetallic superconductors based on the stacking of Pb planes, with crystal structures that display a hexagonal to cubic perovskite-like progression, as rarely seen in metals. The superconducting transition temperatures (Tc) are similar for all −2.2 K for BaPb3, 2.7 K for Ba0.89Sr0.11- Pb3, and 2.6 K for Ba0.5Sr0.5Pb3, and the previously reported Tc of SrPb3, ∼2 K, is confirmed. The materials are moderate coupling superconductors, and calculations show that the electronic densities of states at the Fermi energy are primarily contributed by Pb. The observations suggest that the Pb-stacking variation has only a minor effect on the superconductivity.
A fast time-frequency multi-window analysis using a tuning directional kernel
- Krzysztof Czarnecki
- Dominique Fourer
- François Auger
- Mirosław Rojewski
2018 Pełny tekst SIGNAL PROCESSING
In this paper, a novel approach for time-frequency analysis and detection, based on the chirplet transform and dedicated to non-stationary as well as multi-component signals, is presented. Its main purpose is the estimation of spectral energy, instantaneous frequency (IF), spectral delay (SD), and chirp rate (CR) with a high time-frequency resolution (separation ability) achieved by adaptive fitting of the transform kernel. We propose two efficient implementations of this idea, which allow to use the fast Fourier transform (FFT). In the first one, referred to as “self-tuning”, a previously proposed CR estimation is used for a local fitting of the chirplet kernel over time. For this purpose, we use the CR associated with the dominant (prominent) component. In the second one, we define a new measure for evaluating at each time-frequency point, how the used analyzing window is matched to the signal. This measure is defined as the absolute difference between the estimated CR and the CR parameter associated to the used analysis window. Our method is able to produce combined time-frequency distributions of the spectral energy, IF, SD, and CR. They are obtained using several classical chirplet transforms with analysis windows of various CRs. The compositions are made by finding the lowest fitting measure for every time-frequency points over all transforms. Finally, we assess the robustness of the methods by a detection application and time-frequency localization, both in the presence of high additive white Gaussian noise (additive white Gaussian noise (AWGN)) as well as we present many time-frequency (TF) images of synthetic and real-world signals.
A Framework of A Ship Domain-Based Near-Miss Detection Method Using Mamdani Neuro-Fuzzy Classification
- Tacjana Niksa-Rynkiewicz
- Rafał Szłapczyński
2018 Pełny tekst Polish Maritime Research
Safety analysis of navigation over a given area may cover application of various risk measures for ship collisions. One of them is percentage of the so called near- miss situations (potential collision situations). In this article a method of automatic detection of such situations based on the data from Automatic Identification System (AIS), is proposed. The method utilizes input parameters such as: collision risk measure based on ship’s domain concept, relative speed between ships as well as their course difference. For classification of ships encounters, there is used a neuro-fuzzy network which estimates a degree of collision hazard on the basis of a set of rules. The worked out method makes it possibile to apply an arbitrary ship’s domain as well as to learn the classifier on the basis of opinions of experts interpreting the data from the AIS.
A GPU Solver for Sparse Generalized Eigenvalue Problems with Symmetric Complex-Valued Matrices Obtained Using Higher-Order FEM
- Adam Dziekoński
- Michał Mrozowski
2018 Pełny tekst IEEE Access
The paper discusses a fast implementation of the stabilized locally optimal block preconditioned conjugate gradient (sLOBPCG) method, using a hierarchical multilevel preconditioner to solve nonHermitian sparse generalized eigenvalue problems with large symmetric complex-valued matrices obtained using the higher-order finite-element method (FEM), applied to the analysis of a microwave resonator. The resonant frequencies of the low-order modes are the eigenvalues of the smallest real part of a complex symmetric (though non-Hermitian) matrix pencil. These type of pencils arise in the FEM analysis of resonant cavities loaded with a lossy material. To accelerate the computations, graphics processing units (GPU, NVIDIA Pascal P100) were used. Single and dual-GPU variants are considered and a GPU-memorysaving implementation is proposed. An efficient sliced ELLR-T sparse matrix storage format was used and operations were performed on blocks of vectors for best performance on a GPU. As a result, significant speedups (exceeding a factor of six in some computational scenarios) were achieved over the reference parallel implementation using a multicore central processing unit (CPU, Intel Xeon E5-2680 v3, twelve cores). These results indicate that the solution of generalized eigenproblems needs much more GPU memory than iterative techniques when solving a sparse system of equations, and also requires a second GPU to store some data structures in order to reduce the footprint, even for a moderately large systems
A High-Efficient Measurement System With Optimization Feature for Prototype CMOS Image Sensors
- Miron Kłosowski
- Jacek Jakusz
- Waldemar Jendernalik
- Grzegorz Blakiewicz
- Stanisław Szczepański
- Sławomir Kozieł
2018 Pełny tekst IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT
In this paper, a gray-scale CMOS image sensor (CIS) characterization system with an optimization feature has been proposed. By using a very fast and precise control of light intensity, based on the pulsewidth-modulation method, it is avoided to measure the illuminance every time. These features accelerate the multicriteria CIS optimization requiring many thousands of measurements. The system throughput is 2.5 Gb/s, which allows for capturing images from large arrays of the size 3000 × 3000 pixels at the rate of 25 frames/s, or small arrays (128 × 128) at the rate of 15 000 frames/s. The efficient transfer of measurement data to the external software allows immediate presentation of optimization results in 3-D plots. The system automatically measures nonuniformity, spatial noise, temporal noise, signal-to-noise ratio, dynamic range, nonlinearity and image lag. A flat diffuser has been proposed as a cheaper alternative to an integrating sphere. This optical front-end is particularly useful for testing prototype CISs and vision-chips implemented in standard CMOS technologies as low- or ediumdynamic-range imagers.
A higher order transversely deformable shell-type spectral finite element for dynamic analysis of isotropic structures
- Arkadiusz Żak
- Marek Krawczuk
2018 Pełny tekst FINITE ELEMENTS IN ANALYSIS AND DESIGN
This paper deals with certain aspects related to the dynamic behaviour of isotropic shell-like structures analysed by the use of a higher order transversely deformable shell-type spectral finite element newly formulated and the approach known as the Time-domain Spectral Finite Element Method (TD-SFEM). Although recently this spectral approach is reported in the literature as a very powerful numerical tool used to solve various wave propagation problems, its properties make it also very well suited to solve static and dynamic modal problems. The robustness and effectiveness of the current spectral approach has been successfully demonstrated by the authors in the case of thin-walled spherical shell structures through a series of numerical tests comprising the analysis of natural frequencies and modes of vibration of an isotropic spherical shell as well as the wave propagation analysis in the case of the same spherical shell and a half-pipe shell-like structure.
A HISTORICAL BUILDING'S RESTORATION IN THE CONSTRUCTIONAL ASPECT ON THE EXAMPLE OF A BUILDING LOCATED IN POLAND
- Monika Zielińska
- Karol Grębowski
2018
Objects of cultural heritage are an extremely important element in the proper functioning of the social life. They provide information on our ancestors' actions, as well as shape our culture and social awareness. It is important for the historical objects to provide those information accurately, that is without any unnecessary human intervention over the years of the monument's existence. However, it is not always possible due to the damages influencing the objects. Actions aiming at strengthening the structure need to be taken in a large number of monuments. Nevertheless, the aforesaid strengthening should interfere as little as possible with the historical structure. Examples of such procedures are discussed in this article, on the basis of an object located in the northern part of Poland. The building, unused for years, fell into ruin and required a thorough renovation. The paper discusses strengthening works of both wooden and steel-brick ceilings. The works involving deepening and strengthening of foundations ensuring the stability of the whole building were also presented. Demonstrated was the reinforcement of the walls based on rebuilding, gluing bars in joints, and using a replacement system in the form of a reinforced concrete frame.
A material model of asphalt mixtures based on Monte Carlo simulations
- Cezary Szydłowski
- Jarosław Górski
- Marcin Stienss
- Łukasz Smakosz
2018 Pełny tekst
The paper aims to numerically reflect mineral-asphalt mixture structure by a standard FEM software. Laboratory test results are presented due to bending tests of circular notched elements. The result scatter is relatively high. An attempt was made to form a random aggregate distribution in order to obtain various results corresponding to laboratory tests. The material structure calibration, its homogenization and finite element dimensioning are the issues decisive for the objective mixture description. The representative volume element (RVE) is investigated here, while it does not precisely reflect the material structure it displays relevant global material parameters. The simulation procedure applied here makes it possible to introduce the name of Monte Carlo simulation-based constitutive model.
A Meta-Analysis of Pulse Arrival Time Based Blood Pressure Estimation
- Artur Poliński
- Michał Pietrewicz
- Tomasz Kocejko
- Adam Bujnowski
- Jacek Rumiński
- Jerzy Wtorek
2018
The paper presents a preliminary meta-analysis of the sample correlation between pulse arrival time (PAT) and blood pressure (BP). The aim of the study was to verify sample correlation coefficient between PAT and BP using an affine model BP = a · P AT + b for systolic and diastolic blood pressure. The databases included in the search were the IEEE Xplore Digital Library, Springer Link and Google Scholar. Only papers from 2005 to 2017 were included into analysis. The random-effects model was considered. The resulting sample correlation coefficient was equal to -0.82 (95 % CI; -0.89, -0.72) for systolic blood pressure and -0.64 (95% CI, -0.74 -0.51) for diastolic one. Egger’s regression test showed that there was no evidence of publication bias. Obtained 95% CI intervals for sample correlation coefficients for SBP and DBP are almost separate, which may indicate different relation between PAT and BP for systolic and diastolic pressure
A method for testing the wide-sense stationary uncorrelated scattering assumption fulfillment for an underwater acoustic channel
- Iwona Kochańska
- Ivor Nissen
- Jacek Marszal
2018 Journal of the Acoustical Society of America
Wide-sense stationary and uncorrelated scattering (WSSUS) assumptions are often applied for the statistical description of wireless communication channels. However, in the case of underwater acoustic channels the WSSUS model is of limited value. The degree of similarity of in-phase and quadrature components of the channel impulse response, measured with the use of bandpass modulated signals, can be used as an indicator of WSSUS assumption fulfillment. The paper describes an experimental method that uses quadrature Pseudo-Random Binary Sequence to evaluate the validity of the WSSUS assumption. The technique was developed by analyzing the shallow water experiment in the Bornholm Basin of the Baltic Sea.
A method of determination of electrical conduction mechanisms in complex amorphous materials
- Piotr Kupracz
- Natalia Anna Wójcik
- Ryszard Jan Barczyński
2018 Pełny tekst JOURNAL OF NON-CRYSTALLINE SOLIDS
A novel approach to determine conduction mechanisms in complex amorphous materials was presented and tested on a real system. In the first step of the presented method, total electrical admittance of the material is analyzed in order to separate a couple of processes, each of which can be described by Jonscher's universal dielectric response. In the following step, a temperature dependence of dielectric response parameters of the processes is determined and compared with known models of conduction mechanisms in structural amorphous materials. Using this approach, a presence of two different conduction mechanisms describing electrical conductivity in a two-phase glass was described.
A method of earth fault loop impedance measurement without unwanted tripping of RCDs
- Ryszard Roskosz
- Edward Musiał
- Stanisław Czapp
2018
In low-voltage networks, earth fault loop impedance (EFLI) measurement is the basis for assessing the effectiveness of automatic disconnection of supply. Such a measurement is performed during initial and periodical verification, especially in a TN low-voltage network. Nowadays, due to widespread application of residual current devices (RCDs), such test is difficult in many circuits because RCDs operate during the test. In this paper a method of EFLI measurement, without unwanted tripping of RCDs, is proposed. This method enables the measurement of EFLI using a relatively high value of full-wave testing current. It is recommended in terms of accuracy of the measurement.
A method of Functional Test interval selection with regards to Machinery and Economical aspects
- Jan Piesik
- Emilian Piesik
- Marcin Śliwiński
2018
This paper discusses the problem of choosing the optimal frequency of functional test, including the reliability calculations and production efficiency, but also the effect of company risk management. The proof test as a part of the functional test interval is well described for the process industry. Unfortunately, this situation is not the case for the machinery safety functions with low demand mode. Afterwards, it is presented current approach of companies, which to pursuing industrial excellence monitor their activity through appropriately selected key performance indicators, which enable, among other things, to increase productivity. In addition, companies are increasingly exploring potential risks in the face of new challenges as a part of sophisticated risk management, including the perception of the enterprise plants as a safe place for work, by customers and business partners. In the elimination of potential risks, the influence of human and its interaction with machines is increasingly taken into account. To illustrate the issue a tire cord twisting machines are used in the case study. In this article, the authors propose a solution in the selection of the functional test interval of safety function and complementary protective measures of machinery as a compromise to obtain satisfactory results regarding safety requirements, productivity indicators and risk management issues.
A METHOD OF TRUST MANAGEMENT IN WIRELESS SENSOR NETWORKS
- Janusz Górski
- Alan Turower
2018 International Journal of Security, Privacy an d Trust Management
The research problem considered in this paper is how to protect wireless sensor networks (WSN) against cyber-threats by applying trust management and how to strengthen network resilience to attacks targeting the trust management mechanism itself. A new method, called WSN Cooperative Trust Management Method (WCT2M), of distributed trust management in multi-layer wireless sensor networks is proposed and its performance is evaluated. The method is specified by giving its class model in UML and by explaining the related attributes and methods. Different attacks against the network and against WCT2M deployed in the network are considered. The experimental evaluation of WCT2M involves laboratory experiments and simulations using a dedicated simulator. The evaluation focuses on efficiency of detecting and isolating the malicious nodes that implement different attack scenarios in the network and on the method’s sensitivity to the changes in effectiveness of the security mechanisms deployed in the network nodes.
A Model for Risk Assessment and Management of Construction Projects in Urban Conditions
- Agata Siemaszko
- Beata Grzyl
- Adam Kristowski
2018
The authors are seeking new methods for improving the efficiency of the investments associated with the maintenance and operation of existing civil engineering structures. It is demonstrated how the knowledge about the elements of construction and operation phases and their relationships, combined with monitoring data can be used for more effective management of the risks associated with civil engineering projects. The methodology chosen for estimating the probabilities of risk events is known as Bayesian Belief Networks (BBNs). To better illustrate how the proposed approach works the authors use the example of multi-family residential building located in Gdansk made in the wood-frame technology.
A New Approach for the Mitigating of Flow Maldistribution in Parallel Microchannel Heat Sink
- Kumar Ritunesh
- Gurjeet Singh
- Dariusz Mikielewicz
2018 JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME
The problem of flow maldistribution is very critical in microchannel heat sinks (MCHS). It induces temperature nonuniformity, which may ultimately lead to the breakdown of associated system. In the present communication, a novel approach for the mitigation of flow maldistribution problem in parallel MCHS has been proposed using variable width microchannels. Numerical simulation of copper made parallel MCHS consisting of 25 channels has been carried out for the conventional design (CD) and the proposed design (PD). It is observed that the PD reduces flow maldistribution by 93.7%, which facilitated in effective uniform cooling across the entire projected area of MCHS. Temperature fluctuation at fluid–solid interface is reduced by 4.3 C, whereas maximum and average temperatures of microchannels projected area are reduced by 2.3 C and 1.1 C, respectively. PD is suitable in alleviating flow maldistribution problem for the extended range of off design conditions.
A new approach of coastal cliff monitoring using Mobile Laser Scanning
- Rafał Ossowski
- Paweł Tysiąc
2018 Pełny tekst Polish Maritime Research
The article proposes a new approach of coastal cliff monitoring which bases on a new comprehensive monitoring system, being a combination of mobile scanning from the sea with the geotechnical stability analysis. Mobile laser scanning is an innovative solution for 3D data collection which allows the monitored object geometry to be precisely measured, thus providing opportunities for series of analyses contributing to the development of an improved monitoring system. The authors present selected cliff profiles obtained from mobile scanning in the area of Jastrzebia Gora, complemented by relevant geotechnical analyses. The analysis of current cliff geometry is accompanied by calculations of hypothetical cliff profile changes resulting from possible action of nature forces. Finally, a comprehensive strategy for coastal cliff monitoring is proposed.