Filters
total: 1549
filtered: 1407
-
Catalog
Chosen catalog filters
displaying 1000 best results Help
Search results for: VR CAVES
-
Probabilistic Methods in Reliability Assessment of Engineering Lightweight Structures
PublicationThe paper considers the probability-based analysis of structural safety measures. Two different numerical examples of representative lightweight structures are considered – a submerged truss tower supporting an offshore platform, and an overhead power line support truss tower. On the basis of these examples, the importance of a motivated selection of analysis method and a proper choice of the number of important variables is shown....
-
Detection of debonding in adhesive joints using Lamb wave propagation
PublicationAdhesively bonded joints are widely used in many branches of industry. Mechanical degradation of this type of connections does not have significant symptoms that can be noticed during visual assessment, so non-destructive testing becomes a very important issue. The paper deals with experimental investigations of adhesively bonded steel plates with different defects. Five samples (an intact one and four with damages in the form...
-
Determination of the optimal curvature of the turnout diverging track for HSR using dynamic analysis
PublicationThe paper presents an analytical method of identifying the curvature of the turnout diverging track consisting of sections of varying curvature. Such turnout is mainly applied on High Speed Railway. Both linear and nonlinear (polynomial) curvatures of the turnout diverging track are considered in the paper. Obtained solutions enable to assume curvature values at the beginning and end point of the geometrical layout of the turnout.The...
-
Ultrasonic Tomography of Brick Columns Based on FEM Calculations
PublicationUltrasonic tomography is one of the most developed method of non-destructive testing. Despite being used mainly in medicine, it is becoming more and more popular as a method for monitoring of structural elements. It allows to examine the internal structure and technical condition of the tested element. This paper investigates the influence of crosssectional geometry on an obtained tomographic image. Wave propagation signals were...
-
Corporate social responsibility practices incomes and outcomes: Stakeholders' pressure, culture, employee commitment, corporate reputation, and brand performance. A Polish–German cross‐country study
PublicationThis study aims to compare employee perception of corporate social responsibility (CSR) practice incomes and outcomes in the construction industry in Poland and Germany. It proposes a model that examines the influence of stakeholder pressure, culture, and CSR practices on company brand performance, reputation, and employee identification. The findings suggest that the structure of relationships varies for project‐managed construction...
-
Model Predictive Super-Twisting Sliding Mode Control for An Autonomous Surface Vehicle
PublicationThis paper presents a new robust Model Predictive Control (MPC) algorithm for trajectory tracking of an Autonomous Surface Vehicle (ASV) in presence of the time-varying external disturbances including winds, waves and ocean currents as well as dynamical uncertainties. For fulfilling the robustness property, a sliding mode control-based procedure for designing of MPC and a super-twisting term are adopted. The MPC algorithm has been...
-
Numerical simulations of overflow experiments on a model dike
PublicationDike failure due to overtopping is one of the important factors, which should be considered in the dike designing process. Although the overflow is characterized by the relatively low risk of occurrence, in many cases dikes are totally destroyed or seriously damaged. An interesting phenomenon occurring during overflow is the trapping of air in pores of the unsaturated soil material. As the infiltration progresses from all sides,...
-
Mathematical modeling of hydrogen production performance in thermocatalytic reactor based on the intermetallic phase of Ni3Al
PublicationThe main goal of the following work is to adjust mathematical modelling for mass transfer, to specific conditions resulting from presence of chemical surface reactions in the flow of the mixture consisting of helium and methanol. The thermocatalytic devices used for decomposition of organic compounds incorporate microchannels coupled at the ends and heated to 500 oC at the walls regions. The results of the experiment were compared...
-
Influence of YARN Schedulers on Power Consumption and Processing Time for Various Big Data Benchmarks
PublicationClimate change caused by human activities can influence the lives of everybody onthe planet. The environmental concerns must be taken into consideration by all fields of studyincludingICT. Green Computing aims to reduce negative effects of IT on the environment while,at the same time, maintaining all of the possible benefits it provides. Several Big Data platformslike Apache Spark orYARNhave become widely used in analytics and...
-
Scenarios in the development strategies of larger cities in Poland
PublicationSummary: Planning prepares decisions and future actions. Therefore, future conditions should be considered in planning, in particular strategic planning, due to its long-term nature. To accomplish this, certain prognostic methods should be applied. A scenario method is seen as one of the most useful prognostic method, especially in cases when social and institutional behaviour plays a crucial role. The aim of the paper is an analysis...
-
Effect of solar radiation on current-carrying capacity of PVC-insulated power cables – the numerical point of view
PublicationPower cables are usually buried in the soil, which results in their relatively high current-carrying capacity. However, there are cases in which the starting/final section of a cable line runs along a pole of an overhead power line. Power cables can be directly exposed to solar radiation then, and this negatively influences their current-carrying capacity as well as estimated life of the cables’ insulation. An analysis of thermal...
-
Modelling of Longitudinal Elastic Wave Propagation in a Steel Rod Using the Discrete Element Method
PublicationThe paper deals with the issue of modelling elastic wave propagation using the discrete element method (DEM). The case of a longitudinal wave in a rod with a circular cross-section was considered. A novel, complex algorithm consisting of the preparation of models and simulation of elastic waves was developed. A series of DEM models were prepared for simulations, differing in discretisation and material parameters. Additional calculations...
-
Experimental investigations and damage growth modeling of EN‐AW 2024 aluminum alloy under LCF loading accounting creep pre‐deformation
PublicationThis article presents the results of experimental tests of creep rupture and of low-cycle fatigue (LCF) of EN-AW 2024 aluminum alloy devoid of damage and having preliminary damage. The preliminary damage was dealt in the process of creep at elevated temperature 100C, 200C, and 300C until achievement of two different strain values at each temperature. Samples with preliminary damage were subjected to fatigue tests at room temperature....
-
Performance Evaluation of GAM in Off-Body Path Loss Modelling for Body Area Networks
PublicationThis paper addresses the performance evaluation of an off-body path loss model, based on measurements at 2.45 GHz, which has been developed with the use of the Generalised Additive Model, allowing to model a non-linear dependence on different predictor variables. The model formulates path loss as a function of distance, antennas’ heights, antenna orientation angle and polarisation, results showing that performance is very sensitive...
-
The Impact of Covid-19 on the Performance of Exchange Traded Funds on Developed and Emerging Markets
PublicationIn this paper an endeavour was made to evaluate the impact of Covid-19 on the achievement of the investment objectives by selected ETFs in developed and emerging markets. For this purpose, the tracking errors calculated for 18 different ETFs operating on the basis of American, Asian and European stock indexes were analyzed. The time range of the research was selected in such a way as to compare the period before the pandemic(pre-Covid)...
-
Decoupled Kalman filter based identification of time-varying FIR systems
PublicationWhen system parameters vary at a fast rate, identification schemes based on model-free local estimation approaches do not yield satisfactory results. In cases like this, more sophisticated parameter tracking procedures must be used, based on explicit models of parameter variation (often referred to as hypermodels), either deterministic or stochastic. Kalman filter trackers, which belong to the second category, are seldom used in...
-
Action Plan “Women”
PublicationEmployees of a company are not the first alternative coming into one’s mind when searching suitable successor for the business. Those belonging to the company’s management group are in many cases asked for their interest in being a successor, but the lower level an employee is in the hierarchy, the less probably he/she is inquired of his/her interest in becoming a successor. The contemporary entrepreneur may have had conflicts...
-
SHORT REVIEW AND 3-D FEM ANALYSIS OF BASIC TYPES OF FOUNDATION FOR OFFSHORE WIND TURBINES
PublicationSome problems of the foundations of offshore wind turbines are considered in this paper. A short review is presented on the two basic types of foundations, i.e. monopiles and gravity foundations, including their basic features and applications as well as general design considerations. Also, some issues regarding analysis are discussed, including geotechnical problems and modelling techniques. A numerical model of offshores turbine...
-
Improving Clairvoyant: reduction algorithm resilient to imbalanced process arrival patterns
PublicationThe Clairvoyant algorithm proposed in “A novel MPI reduction algorithm resilient to imbalances in process arrival times” was analyzed, commented and improved. The comments concern handling certain edge cases in the original pseudocode and description, i.e., adding another state of a process, improved cache friendliness more precise complexity estimations and some other issues improving the robustness of the algorithm implementation....
-
Evaluation of applicability of classic methods of a fault loop impedance measurement to circuits with residual current devices
PublicationMeasurement of fault loop impedance in low voltage grids and systems is in most cases performed to verify the effectiveness of protection against electric shock by automatic disconnection of supply. For the sake of measurement accuracy, it is advisable to perform it using large current. Unfortunately, in circuits with residual current devices which are very widely used nowadays, a large measurement current may trigger those devices...
-
Three-dimensional mapping for data collected using variable stereo baseline
PublicationThe paper describes a system of 3D mapping of data collected with due regard for variable baseline. This solution constitute an extension to a VisRobot sub-system developed as a subsystem, necessary for implementing the generic idea of using mobile robots to explore an indoor static environment. This subsystem is to acquire stereo images, calculate the depth in the images and construct the sought 3D map. Stereo images are obtained...
-
Material for Automatic Phonetic Transcription of Speech Recorded in Various Conditions
PublicationAutomatic speech recognition (ASR) is under constant development, especially in cases when speech is casually produced or it is acquired in various environment conditions, or in the presence of background noise. Phonetic transcription is an important step in the process of full speech recognition and is discussed in the presented work as the main focus in this process. ASR is widely implemented in mobile devices technology, but...
-
Estimating Traffic Intensity Employing Passive Acoustic Radar and Enhanced Microwave Doppler Radar Sensor
PublicationInnovative road signs that can autonomously display the speed limit in cases where the trac situation requires it are under development. The autonomous road sign contains many types of sensors, of which the subject of interest in this article is the Doppler sensor that we have improved and the constructed and calibrated acoustic probe. An algorithm for performing vehicle detection and tracking, as well as vehicle speed measurement,...
-
Process arrival pattern aware algorithms for acceleration of scatter and gather operations
PublicationImbalanced process arrival patterns (PAPs) are ubiquitous in many parallel and distributed systems, especially in HPC ones. The collective operations, e.g. in MPI, are designed for equal process arrival times (PATs), and are not optimized for deviations in their appearance. We propose eight new PAP-aware algorithms for the scatter and gather operations. They are binomial or linear tree adaptations introducing additional process...
-
Numerical Study of Concrete Mesostructure Effect on Lamb Wave Propagation
PublicationThe article presents the results of the numerical investigation of Lamb wave propagation in concrete plates while taking into account the complex concrete mesostructure. Several concrete models with randomly distributed aggregates were generated with the use of the Monte Carlo method. The influence of aggregate ratio and particle size on dispersion curves representing Lamb wave modes was analyzed. The results obtained for heterogeneous...
-
Detekcja i lokalizacja nieprzewodzenia tranzystorów falownika napięcia na podstawie analizy prądu obciążenia
PublicationPrzedstawiono nową metodę detekcji i lokalizacji nieprzewodzenia tranzystorów w falownikach napięcia zasilających silniki indukcyjne małej mocy. Metoda bazuje na monitorowaniu wartości dwóch sygnałów dia-gnostycznych. Pierwszy z nich, wskaźnik braku przepływu prądu, wykorzystano w celu detekcji uszkodzeń. Drugi, stosunek wartości średniej prądu do wartości średniej bezwzględnej, zawiera informacje umożliwiające lokalizację uszkodzonych...
-
Modelling of Asphalt Mixes under Long Time Creep at Low Temperatures
PublicationProper description of asphalt mixtures behavior under long time load is one of the most important factors in analyses of strain and stress relations at low temperatures both from traffic and environmental loads. For example different models of thermal stress accumulation require different approaches of description of asphalt concrete. But in all cases it is required to describe its behavior under long time loading, which in some...
-
Empirical analysis of tree-based classification models for customer churn prediction
PublicationCustomer churn is a vital and reoccurring problem facing most business industries, particularly the telecommunications industry. Considering the fierce competition among telecommunications firms and the high expenses of attracting and gaining new subscribers, keeping existing loyal subscribers becomes crucial. Early prediction of disgruntled subscribers can assist telecommunications firms in identifying the reasons for churn and...
-
Love your mistakes!—they help you adapt to change. How do knowledge, collaboration and learning cultures foster organizational intelligence?
PublicationPurpose: The study aims to determine how the acceptance of mistakes is related to adaptability to change in a broad organizational context. Therefore it explores how knowledge, collaboration, and learning culture (including “acceptance of mistakes”) might help organizations overcome their resistance to change. Methodology: The study uses two sample groups: students aged 18–24 (330 cases) and employees aged >24 (326 cases) who work...
-
A Regular Expression Matching Application with Configurable Data Intensity for Testing Heterogeneous HPC Systems
PublicationModern High Performance Computing (HPC) systems are becoming increasingly heterogeneous in terms of utilized hardware, as well as software solutions. The problems, that we wish to efficiently solve using those systems have different complexity, not only considering magnitude, but also the type of complexity: computation, data or communication intensity. Developing new mechanisms for dealing with those complexities or choosing an...
-
Guided wave propagation in diagnostic of steel elements
PublicationThis paper is devoted to numerical investigations of elastic wave propagation in steel elements. The aim of this study is to conduct numerical analysis and experimental investigations on the propagation of elastic waves in steel elements in the context of damage detection. In particular, this paper is devoted to detection of damage occurring in the form of notch or changed thickness. This approach utilized the fact that any discontinuities...
-
Guided wave propagation in diagnostic of steel elements
PublicationThis paper is devoted to numerical investigations of elastic wave propagation in steel elements. The aim of this study is to conduct numerical analysis and experimental investigations on the propagation of elastic waves in steel elements in the context of damage detection. In particular, this paper is devoted to detection of damage occurring in the form of notch or changed thickness. This approach utilized the fact that any discontinuities...
-
Development of Local IDF-formula Using Controlled Random Search Method for Global Optimization
PublicationThe aim of the study is to present the effective and relatively simple empirical approach to rainfall Intensity-Duration-Frequency-formulas development, based on Controlled Random Search (CRS) for global optimization. The approach is mainly dedicated to the cases in which the commonly used IDF-relationships do not provide satisfactory fit between simulations and observations, and more complex formulas with higher number of parameters...
-
Eqiuitable coloring of corona products of cubic graphs is harder than ordinary coloring
PublicationA graph is equitably k-colorable if its vertices can be partitioned into k independent sets in such a way that the number of vertices in any two sets differ by at most one. The smallest k for which such a coloring exists is known as the equitable chromatic number of G. In this paper the problem of determinig the equitable coloring number for coronas of cubic graphs is studied. Although the problem of ordinary coloring of coronas...
-
Effect of adhesive compliance in the assessment of soft adhesives with the wedge test
PublicationWedge tests are usually analysed assuming that the free, unbonded members may be treated as encastré cantilever beams. However, if the adhesive layer is sufficiently flexible (e.g., due to low elastic modulus), then significant strain in the bonded region may occur and lead to modification of the behaviour outside this region. Using in conjunction a sensitive strain gauge method on asymmetric wedge tests and a mathematical analysis...
-
Numerical analysis of the container vessel's self-propulsion at different rudder deflection angles
PublicationNowadays, CFD becomes one of the most commonly used research method in ship hydrodynamics, limited to the analyses of hull resistance in calm water. With continuously improving computing power and increasingly more accurate numerical methods it is possible to simulate more complex cases. State of the art CFD tools also enable development of new ways of assessing ship maneuvering performance. This paper presents an attempt on...
-
Application of electrochemical impedance spectroscopy to monitoring discharging process of nickel/metal hydride battery.
PublicationThis paper presents the possibility of applying impedance analysis to cell diagnostics. In order to obtain characteristic curves of both electrodes of a NiMH battery simultaneously, a reference electrode was added into the circuit. The authors analysed the cell under three cases, i.e. when its properties are determined only by the state of the positive electrode, only by the state of the negative electrode, or when both electrodes...
-
Influence of compaction effectiveness on interlayer bonding of asphalt layers
PublicationThe paper presents the results of research on the interlayer bonding of asphalt layers compacted in the laboratory and in the field. To measure the interlayer bonding at a temperature of 20°C the Leutner test apparatus was used and load was applied at a rate of 50 mm/minute. Three types of interlayer interfaces were tested: no tack coat and tack coats made of two types of the pure bitumen emulsions. Four compaction techniques were...
-
Experimental and theoretical solubility advantage screening of bi-component solid curcumin formulations
PublicationA comprehensive experimental and theoretical screening was performed for identification of curcumin solubilizers. Experimental data led to formulation of a non-linear QSPR model correlating molecular descriptors with measured solubilities. The majority of synthesized binary systems exhibited a moderate enhancement of curcumin solubility, which was found to be the highest in the case of curcumin cocrystallized with pyrogallol. New...
-
Friction and Lubrication of Large Tilting-Pad Thrust Bearings
PublicationFluid film bearings have been extensively used in the industry because of their unbeatable durability and extremely low friction coefficient, despite a very low coefficient of friction dissipation of energy being noticeable, especially in large bearings. Lubricating systems of large tilting pad thrust bearings utilized in large, vertical shaft hydrogenerators are presented in this paper. A large amount of heat is generated due...
-
Rapid design of miniaturised branch-line couplers through concurrent cell optimisation and surrogate-assisted fine-tuning
PublicationIn this study, the authors introduce a methodology for low-cost simulation-driven design optimisation of highly miniaturised branch-line couplers (BLCs). The first stage of their design approach exploits fast concurrent optimisation of geometrically dependent, but electromagnetically isolated cells that constitute a BLC. The cross-coupling effects between the cells are taken into account in the second stage, where a surrogate-assisted...
-
On IPSec Performance Testing of IPv4/IPv6 IPSec Gateway
PublicationZapewnienie, że brama IPSec (ang. Internet Protocol Security) spełnia oczekiwania wydajnościowe jest jednym z najważniejszych wyzwań, przed jakimi stoi zespół projektowy tworzący ten produkt. Jedynie odpowiednie podejście do walidacji może zagwarantować, że przepustowość ruchu IPSec bramy jest na oczekiwanym poziomie, czas dodawania/usuwania konfiguracji SA (ang. Security Associations) jest akceptowalny, brama IPSec jest w stanie...
-
Purification and biochemical characteristic of a cold-active recombinant esterase from Pseudoalteromonas sp. 643A under denaturing conditions.
PublicationIn this paper production of a cold-active esterase EstA from the Antarctic bacterium Pseudoalteromonas sp. 643A in E. coli expression system was described. The purification and biochemical characteristic of EstA were performed in the presence of urea and then compared with results obtained for the esterase with no addition of urea and isolated from the native source. In both cases the cold-active enzyme displayed similar properties....
-
Electron impact iozization of CCl4 and SF6 embedded in superfluid helium droplets
PublicationElectron impact ionization of helium nano-droplets containing several 104 He atoms and doped with CCl4 or SF6 molecules is studied with high-mass resolution. The mass spectra show significant clustering of CCl4 molecules, less so for SF6 under our experimental conditions. Positive ion efficiency curves as a function of electron energy indicate complete immersion of the molecules inside the helium droplets in both cases. For CCl4...
-
Acoustic streaming caused by some types of aperiodic sound. Buildup of acoustic streaming
PublicationThe analysis of streaming caused by aperiodic sound of different types (switched on at transducer sound or sound determined by initial conditions) is undertaken. The analysis bases on analytical governing equation for streaming Eulerian velocity, which is a result of decomposition of the hydrodynamic equations into acoustic and non-acoustic parts. Its driving force (of acoustic nature) represents a sum of two terms; one is the...
-
TIME-AND-SPACE STRUCTURE OF FORCE-DRIVEN RIGID SPHEREWAVEFIELD
PublicationThis paper introduces a time-domain, causality-inspired description of a vector-source acoustic wavefield of arbitrary time evolution, where a sphere is a practical realisation of quasi-point contact surface without which a point force would not be able to exert an impact onto non-viscous fluid. At every space location, the resulting acoustic field is described by a pair of physical variables characterising the time evolution of...
-
Analysis of unsteady flow forces on the thermowell of steam temperature sensor
PublicationIn this paper, 3D numerical analysis of unsteady flow forces acting on the measuring sheath of steam temperature is presented. According to that purpose, the CFD (Computation Fluid Dynamic [1]) approach has been used. The nonstationary of fluid acting on the measuring sheath such as: Strouhal frequency, amplitude of pressure, structure of vortex, peak of pressure, field of pressure, field of velocity etc. are studied analytically...
-
Municipal wastewater reclamation: Reclaimed water for hydrogen production by electrolysis – A case study
PublicationThis paper presents an analysis of a treatment system selection for municipal wastewater stream based on the DuPont Water Solutions WAVE software. The results obtained based on an analysis of 7 different processing cases studies (ultrafiltration and reverse osmosis) confirmed that the application of 2-pass membrane systems enables the reclamation of water from municipal wastewater that fulfills the requirements concerning the...
-
Modeling lubricant flow between thrust-bearing pads
PublicationInlet temperature is one of the main inputs in all models for the analysis of fluid film bearing performance. At the same time, inlettemperature distribution and also oil velocity distribution at the inlet are the result of flow phenomena in the gap between the bearingpads. These phenomena are complex and in many cases further affected by any special arrangements of forced oil supply to the gapbetween pads. The reason for such...
-
Two examples of Quantum Dynamical Semigroups
PublicationThe Hamiltonians of the considered bi-partite systems are of the form $$ H_{S,R} = H_S /times 1_R + Q_{S} /times M_R + 1_S /times H_R $$ Subindex $S$ corresponds to the observed system and $R$ to the reservoir (the enviroment of $S$). Two classes of systems are distinguished: the discrete-continuous...