Filters
total: 21945
filtered: 9392
displaying 1000 best results Help
Search results for: ACOUSTIC JOURNAL BEARING
-
The development of an underwater telephone for digital communication purposes
PublicationThe underwater telephone HTL-10 has been designed to provide voice and data communication between helicopter and submarines using acoustic waves. It works in a half-duplex mode and uses analogue power-efficient modulation in the form of a single side-band, suppressed carrier, in a wide range of frequencies. It generates the transmitted signal, and processes the received signals. It is implemented with the use of digital signal...
-
Auxetic foams
PublicationThis paper presents a method of producing auxetic polyurethane foams (PUFs) and their unique properties. The experience was based on a synthesis of traditional flexible polyurethane foam and thermal conversion to auxetic foam. The foam specimens were transformed from conventional Poisson's ratio to auxetic (negative Poisson's ratio) [1]. Basic research was performed to determine the mechanical properties and cell structure. Auxetic...
-
Do Leonardo da Vinci’s drawings, room acoustics and radio astronomy have anything in common?
PublicationAfter introducing Leonardo da Vinci’s (LdV) predecessors in the field of light propagation research, his drawings on the topic of reflecting light by a spherical mirror are analysed. The discovery of LdV is presented, according to which, at an infinitely distant source of rays, a small fragment of the canopy is enough to generate a focus, while the rest of the mirror forms a caustic for which LdV did not indicate an application....
-
Shear fracture of longitudinally reinforced concrete beams under bending using Digital Image Correlation and FE simulations with concrete micro-structure based on X-ray micro-computed tomography images
PublicationThe paper presents experimental and numerical investigations of the shear fracture in rectangular concrete beams longitudinally reinforced with steel or basalt bar under quasi-static three point bending. Shear fracture process zone formation and development on the surface of beams was investigated by Digital Image Correlation (DIC) whereas thorough analyses of 3D material micro-structure, air voids, width and curvature of shear...
-
Photochemical Rearrangement of a 19-Membered Azoxybenzocrown: Products and their Properties
PublicationThe preparation and characterization of products of the chemical and photochemical rearrangements of a 19-membered o,o'-azoxybenzocrown were presented. In photochemical rearrangement, besides expected product i.e. 19-membered o-hydroxy-o,o'-azobenzocrown (19-o-OH), obtained under defined conditions with 75% yield, also other macrocyclic products were isolated and identified, namely: 19-membered p-hydroxy-o,o'-azobenzocrown (19-p-OH),...
-
A Proposed Machine Learning Model for Forecasting Impact of Traffic-Induced Vibrations on Buildings
PublicationTraffic-induced vibrations may cause various damages to buildings located near the road, including cracking of plaster, cracks in load-bearing elements or even collapse of the whole structure. Measurements of vibrations of real buildings are costly and laborious. Therefore the aim of the research is to propose the original numerical algorithm which allows us to predict, with high probability, the nega-tive dynamic impact of traffic-induced...
-
Materials Design for the Titanium Scaffold Based Implant
PublicationThe main objective of here presented research is a design the scaffold/porous titanium(Ti) alloy based composite material demonstrating better biocompatibility, longer lifetime andbioactivity behaviour for load-bearing implants. The development of such material is proposed bymaking a number of consecutive tasks. Modelling the mechanical, biomechanical and biologicalbehavior of porous titanium structure and an elaboration of results...
-
Materials Design for the Titanium Scaffold Based Implant
PublicationThe main objective of here presented research is a design the scaffold/porous titanium(Ti) alloy based composite material demonstrating better biocompatibility, longer lifetime andbioactivity behaviour for load-bearing implants. The development of such material is proposed bymaking a number of consecutive tasks. Modelling the mechanical, biomechanical and biologicalbehavior of porous titanium structure and an elaboration of results...
-
Tacit Knowledge Sharing and Project Performance. Does the Knowledge Workers' Personal Branding Matter?
PublicationTacit knowledge sharing is the real challenge for knowledge management today. Network economy has completely changed the role of knowledge workers who now become independent tacit knowledge producers. Bearing this fact in mind, the author studied how tacit knowledge sharing affects the process of building a personal brand and project performance. For this purpose, the authors conducted a study among Polish professionals with different...
-
Tetrahydroquinolinone derivatives exert antiproliferative effect on lung cancer cells through apoptosis induction
PublicationThe anticancer properties of quinolones is a topic of interest among researchers in the scientific world. Because these compounds do not cause side effects, unlike the commonly used cytostatics, they are considered a promising source of new anticancer drugs. In this work, we designed a brief synthetic pathway and obtained a series of novel 8-phenyltetrahydroquinolinone derivatives functionalized with benzyl-type moieties at position...
-
The Motion Analysis of Attacus Atlas Rigid Wing
PublicationThe remarkable aerodynamic efficiency of flapping insect wings has fascinated researchers for many years. Butterfly wings are distinguished by a much larger lifting surface, and thus, a different style of flapping flight. The considerations described in the article are an introduction to a fully flexible analysis of the wing in motion. The study of the rigid wing gives the basic knowledge necessary in the further process. The yaw,...
-
Development of Safirinium dyes for new applications: fluorescent staining of bacteria, human kidney cells, and the horny layer of the epidermis
PublicationLow-molecular synthetic fluorophores are convenient tools in bioimaging applications. Several derivatives of Safirinium dyes as well as their reactive N-hydroxysuccinimide (NHS) esters bearing diverse substituents were synthesized and evaluated experimentally in terms of their lipophilicity by means of reverse-phase and immobilized artificial membrane high-performance liquid chromatography. Subsequently, the selected compounds...
-
Phosphinophosphoranes: Mixed-Valent Phosphorus Compounds with Ambiphilic Properties
PublicationHerein, we present a simple synthesis of mixed-valent phosphinophosphoranes bearing three- and five-coordinate phosphorus centers. Compounds with phosphorus–phosphorus bonds were synthesized via a reaction of lithium phosphides RR′PLi with cat2PCl (cat = catecholate), whereas derivatives with methylene-linked phosphorus centers were obtained via a reaction of phosphanylmethanides RR′CH2Li with cat2PCl. The presence of accessible...
-
Multivariate Assessment of Procedures for Molecularly Imprinted Polymer Synthesis for Pesticides Determination in Environmental and Agricultural Samples
PublicationIn the case of quantitative and qualitative analysis of pesticides in environmental and food samples, it is required to perform a sample pre-treatment process. It allows to minimalize the impact of interferences on the final results, as well as increase the recovery rate. Nowadays, apart from routinely employed sample preparation techniques such as solid-phase extraction (SPE) or solid-phase microextraction (SPME), the application...
-
Analysis of Failure Mechanism in Joints with Positive Eccentricity in CFS Truss
PublicationThe paper presents studies concerning the load-bearing capacity of truss joints with a positive eccentricity resulting from the arrangement of geometric members and the failure mechanisms observed in the joints. Based on the previously conducted experimental study, a numerical model of the tested fragment of the CFS truss with eccentricity in the joint was created and validated. All structural details of the tested truss and the...
-
Vibro piles performance prediction using result of CPT
PublicationVibro piles belong to the group of full displacement piles with an expanded base, characterised by a very high load capacity, especially in non-cohesive soils. The problem is to adopt a reliable method for the determination of full load–settlement (Q–s) curve. A frequent difficulty is the determination of the load capacity limit based on the static load test because the course of the load–settlement curve is of a linear nature....
-
Analiza wielokryterialna wariantów systemu zaopatrzenia w wodę zespołu padów
PublicationJednym z istotnych problemów decyzyjnych na etapie potencjalnej eksploatacji gazu z formacji łupkowych jest wybór sposobu zaopatrzenia w wodę kopalni gazu łupkowego. Z uwagi na duże zapotrzebowanie na wodę do procesu szczelinowania kolejno przekazywanych do eksploatacji odwiertów wydobywczych, należy poszukiwać systemu zaopatrzenia w wodę, który zagwarantuje wymaganą jej ilość, a jednocześnie nie będzie zbyt dużym obciążeniem dla...
-
Reactive Sintering of Ground Tire Rubber (GTR) Modified by a Trans-Polyoctenamer Rubber and Curing Additives
PublicationThe proposed method of ground tire rubber (GTR) utilization involves the application of trans-polyoctenamer rubber (TOR), a commercially available waste rubber modifier. The idea was to investigate the influence of various curing additives (sulfur, N-cyclohexyl-2-benzothiazole sulfenamide (CBS), dibenzothiazole disulfide (MBTS) and di-(2-ethyl)hexylphosphorylpolysulfide (SDT)) on curing characteristics, physico-mechanical, thermal,...
-
Application of Shape From Shading Technique for Side Scan Sonar Images
PublicationSide scan sonar (SSS) is one of the most widely used imaging systems in the underwater environment. It is relatively cheap and easy to deploy in comparison with more powerful sensors like multibeam echosounder or synthetic aperture sonar. Although, the SSS does not provide directly the seafloor bathymetry measurements. Its outputs are usually in a form of grey level acoustic images of seafloor. However, the analysis of such images...
-
Using wavelet techniques for multibeam sonar bathymetry data compression
PublicationMultibeam sonars are widely used in applications like high resolution bathymetry measurements or underwater object imaging. One of the significant problems in multibeam sensing of the marine environment is large amount of data which must be transmitted from the sonar processing unit to an operator station using a limited bit rate channel. For instance, such a situation would be in the case when the multibeam sonar was mounted on...
-
On the compression of multibeam sonar raw bathymetry data
PublicationMultibeam sonars are widely used in applications like high resolution bathymetry measurements or underwater object imaging. One of the significant problems in multibeam sensing of the marine environment is large amount of data which must be transmitted from the sonar processing unit to an operator station using a limited bit rate channel. For instance, such a situation would be in the case when the multibeam sonar was mounted on...
-
Separability Assessment of Selected Types of Vehicle-Associated Noise
PublicationMusic Information Retrieval (MIR) area as well as development of speech and environmental information recognition techniques brought various tools in-tended for recognizing low-level features of acoustic signals based on a set of calculated parameters. In this study, the MIRtoolbox MATLAB tool, designed for music parameter extraction, is used to obtain a vector of parameters to check whether they are suitable for separation of...
-
Propagation Characteristics of Partial Discharges in an Oil-Filled Power Transformer
PublicationPower transformers are among the most important assets in the power transmission and distribution grid. However, they suffer from degradation and possible faults causing major electrical and financial losses. Partial discharges (PDs) are used to identify the insulation health status and their degradation level. PDs are incipient, low-magnitude faults caused by localized dielectric breakdown. Those activities emit signals in many...
-
Comparison of Doppler Effect Estimation Methods for MFSK Transmission in Multipath Hydroacoustic Channel
PublicationUnderwater wireless communication remains a challenging topic, particularly for applications such as wreck penetration where multipath and Doppler effects are very intense. These effects are becoming even more difficult to mitigate for fast data transmission systems that utilize wideband signals. Due to the low propagation speed of acoustic wave in the water, there is a significant difference between the Doppler shift for lower...
-
Analysis of Impulse Responses Measured in Motion in a Towing Tank
PublicationThe growing interest in developing autonomous underwater vehicles (AUVs) and creating underwater sensor networks (USNs) has led to a need for communication tools in underwater environments. For obvious reasons, wireless means of communication are the most desirable. However, conducting research in real conditions is troublesome and costly. Moreover, as hydroacoustic propagation conditions change very significantly, even during...
-
Analysis of Impulse Responses Measured in Motion in a Towing Tank
PublicationThe growing interest in developing autonomous underwater vehicles (AUVs) and creating underwater sensor networks (USNs) has led to a need for communication tools in underwater environments. For obvious reasons, wireless means of communication are the most desirable. However, conducting research in real conditions is troublesome and costly. Moreover, as hydroacoustic propagation conditions change very significantly, even during...
-
Application of twin-plane ECT sensor for identification of the internal imperfections inside concrete beams
PublicationThe main purpose of this paper is to investigate application of special construction of Electrical Capacitance Tomography (ECT) sensor to concrete beams internal homogeneity tests. Identification of internal imperfection inside the concrete beams is one of the main problems related to analysis of the construction structure bearing capacity. Therefore, this paper shows attempts to study the measurement prospects for this non-invasive,...
-
Selected elements of the methodology and method of designing amphibious flood rescue vehicles
PublicationThe methodology of designing amphibious flood rescue vehicles at the preliminary stage of the design process has been presented. The study has been focused on the properties of such vehicles when afloat, with their on-land behaviour and performance characteristics having been left aside. In the study, a general assumption has been made that the amphibious flood rescue vehicles should be designed as, above all, watercraft that additionally...
-
Operational problems of large power diesel engines combusting biofuels, considered togetherwith assessment of their operation
PublicationWithin this article the issue of large power self ignition engines fed with biofuels has been undertaken. The analysis focused mainly on operation problems. There has been noticed some advantages and difficulties associated with the biofuel application to self ignition engines. The research problem has been characterised and the research purposes have been proposed enabling the most profitable formation of energetic features of...
-
Groundwater Quality in the Gdansk Aquifer System
PublicationThe Gdańsk hydrogeological system consists of three main aquifers: Cretaceous, Paleogene-Neogene and Pleistocene. Chemical composition of groundwater varies between water-bearing beds, although water from Pleistocene and Paleogene-Neogene aquifers shows much similarities. The dominant hydrochemical groundwater types is HCO3-Ca. This type is characteristic for Pleistocene deposits in the Kashubian Lake District where natural chemical...
-
Tacit Knowledge Sharing and Creativity. How to Derive Innovation from Project Teams?
PublicationModern companies are increasingly likely to work in a project management environment, which ensures their success in the implementation of innovation. The aim of the study is to prove that tacit knowledge is a mediator for creativity and project performance. Creativity as one of the crucial sources of innovation is stimulated by tacit knowledge. Bearing this fact in mind, the authors studied relations between tacit knowledge, creativity...
-
Novel condition monitoring of induction motor bearings via motor current signature analysis
PublicationThe paper authors are researching the assessment of bearing conditions in induction motors. The methods developed by the authors are based on measurements and analysis of the motor supply current, which is particularly attractive in the absence of access to the engine. The article provides an overview of selected methods of induction motor bearings diagnostic based on Motor Current Signature Analysis (MCSA). However, there is no...
-
Load-carrying capacity of axially loaded concrete-filled steel tubular columns made of thin tubes
PublicationAn experimental investigation was conducted on 30 CFST columns. An influence of the following factors on load-carrying capacity of the investigated columns was analyzed: the column slenderness (l1 = 42, l2 = 27 and l3 = 15), the tube thickness (the reinforcement ratio was equal to 4% or 6%), the way of applying the load to CFST columns (through the concrete core or through the entire cross-section), the bond strength between a...
-
Effects of electrophoretic deposition times and nanotubular oxide surfaces on properties of the nanohydroxyapatite/nanocopper coating on the Ti13Zr13Nb alloy
PublicationLoad-bearing implants are developed with a particular emphasis placed on an application of ceramic hydroxyapatite coatings in order, to enhance the bioactivity of titanium implants and to shorten the healing time. Therefore, thin, fully crystalline coatings that are, highly adhesive, hydrophilic and demonstrating antibacterial properties are ly looked for. The aim of this research was to develop and characterize the properties...
-
Prognozowanie wpływu drgań komunikacyjnych na budynki mieszkalne za pomocą sztucznych sieci neuronowych i maszyn wektorów wspierających
PublicationDrgania komunikacyjne mogą stanowić duże obciążenie eksploatacyjne budynku, powodując zarysowania i spękania tynków, odpadanie wypraw, zarysowania konstrukcji, pękanie elementów konstrukcji lub nawet zawalenie się budynku. Pomiary drgań na rzeczywistych konstrukcjach są pracochłonne i kosztowne, a co ważne nie w każdym przypadku są one uzasadnione. Celem pracy jest analiza autorskiego algorytmu, dzięki któremu z dużym prawdopodobieństwem...
-
Multistatyczny, Dopplerowski System określania położenia i prędkości ruchomych celów w wodzie
PublicationW omawianym w pracy multistatycznym, dopplerowskim systemie określania położenia i prędkości ruchomych celów w wodzie źródłem sygnału są dwa nadajniki emitujące sinusoidalne, akustyczne fale ciągłe o różnych częstotliwościach, które po odbiciu od ruchomego celu są obierane przez cztery hydrofony. W artykule przedstawiono analize teoretyczna efektu Dopplera, na którym oparte jest działanie systemu oraz metodę rozwiązania głównych...
-
An in-depth look at the tire rubber hardness influence on tire/road noise measurements
PublicationWhen assessing the acoustic quality of a road pavement with the close-proximity (CPX) or the on-board sound intensity (OBSI) method, the rubber hardness of the reference tire substantially affects the measurement. Practical experience shows that measurement tires can get significantly harder within a single measurement season. This is why one would like to normalize measurements to a reference rubber hardness. The recently published...
-
Vertical Temperature Stratification of the Gulf of Gdansk Water
PublicationThe Baltic Sea is characterized by variable hydroacoustic conditions, which depend on hydrological conditions throughout the year. The temperature of the water is the factor that has the greatest impact on the changes in the speed of the sound in this basin. Even at a small depth, we can observe a large temperature gradient affecting the accuracy of the conducted research using hydroacoustic devices. A characteristic feature of...
-
Investigation of Noise Threats and Their Impact on Hearing in Selected Schools
PublicationNoise measurements conducted in selected schools in Gdansk area are presented in this paper. The main aim of this research was to determine noise threats at schools. Some objective measurements of the acoustic climate were performed employing a noise monitoring station engineered at the Multimedia System Department, Gdansk University of Technology. Simultaneously, subjective noise annoyance examinations were carried out among pupils...
-
Investigation of noise threats and their impact on hearing in selected schools - a pilot study.
PublicationNoise measurements conducted in selected schools in Gdansk area are presented in this paper. The main aim of this research was to determine noise threats at schools. Some objective measurements of the acoustic climate were performed employing a noise monitoring station engineered at the Multimedia System Department, Gdansk University of Technology. Simultaneously, subjective noise annoyance examinations were carried out among pupils...
-
Nonlinear Modeling in Time Domain Numerical Analysis of Stringed Instrument Dynamics
PublicationMusical instruments are very various in terms of sound quality with their timbre shaped by materials and geometry. Materials' impact is commonly treated as dominant one by musicians, while it is unclear whether it is true or not. The research proposed in the study focuses on determining influence of both these factors on sound quality based on their impact on harmonic composition. Numerical approach has been chosen to allowed independent...
-
Effective degradation of sulfide ions and organic sulfides in cavitation-based Advanced Oxidation Processes (AOPs)
PublicationThe paper presents the results of investigations on the effectiveness and reaction rate constants of the oxidation of sulfide ions and organic sulfides in real industrial effluents from the production of bitumens (2000 mg S2- L-1) using hydrodynamic and acoustic cavitation. The content of the effluents was analysed in terms carbon disulfide, dimethyl sulfide, and di-tert-butyl disulfide concentration. A possibility of complete...
-
Estimation of Average Speed of Road Vehicles by Sound Intensity Analysis
PublicationConstant monitoring of road traffic is important part of modern smart city systems. The proposed method estimates average speed of road vehicles in the observation period, using a passive acoustic vector sensor. Speed estimation based on sound intensity analysis is a novel approach to the described problem. Sound intensity in two orthogonal axes is measured with a sensor placed alongside the road. Position of the apparent sound...
-
Non-destructive Testing of Wooden Elements
PublicationExamining the condition of wooden elements is crucial from the perspective of proper structure performance. If the deterioration in the internal wood condition, which displays no symptoms visible from the outside, is detected, the further spread of the deterioration can be prevented. Test results often point to the necessity of conducting repairs and, renovations, replacing the structure of wooden beams, or even substituting a...
-
Low-Voltage Low-Power Filters with Independent ω0 and Q Tuning for Electronic Cochlea Applications
PublicationAn acoustic second-order low-pass filter is proposed for filter banks emulating the operation of a human cochlea. By using a special filter structure and an innovative quality (Q)-factor tuning technique, an independent change of the cutoff frequency (ω0) and the Q-factor with unchanged gain at low frequencies is achieved in this filter. The techniques applied result in a simple filter design with low Q-factor sensitivity to component...
-
Powder metallurgy of the porous Ti-13Nb-13Zr alloy of different powder grain size
PublicationThe objective of the present project was to determine the effects of powder granulation (fraction of grain size) for the Ti-13Nb-13Zr alloy, produced by powder metallurgy, on its porosity, grain cohesion, compressive strength, and Young`s modulus. Two powder fractions, 45–105 µm, and 106–250 µm were applied. The 50 mass pct of NH4HCO3 was added as a space holder. The specimens were in compaction stage uniaxially pressed at pressure...
-
Yerba Mate - A Long but Current History
PublicationBearing in mind the growing interest in Yerba Mate, a comprehensive study has been prepared containing the most important aspects and possibilities of its use. The introduction of the work contains the species characteristics of Yerba Mate, as well as information about the origin and places of cultivation. The next part focuses on the analysis of the composition, pointing to purine alkaloids, polyphenols, saponins, and minerals...
-
The influence oil additives on spread cracks in silicon nitride
PublicationThe paper presents an experimental study of the influence of oil additives (Cl, S, P, cerium dioxide (CeO2)) on spread cracks in silicon nitride. The additives Cl, S, P are bound in molecules in liquid form soluble in the base oil. The CeO2 is purely in powder form in suspension. The use of CeO2 powder was made based on the good results of polishing of silicon nitride. A ceramic angular contact ball bearing was modelled using a...
-
Supply current signal and artificial neural networks in the induction motor bearings diagnostics
PublicationThis paper contains research results of the diagnostics of induction motor bearings based on measurement of the supply current with usage of artificial neural networks. Bearing failure amount is greater than 40% of all engine failures, which makes their damage-free operation crucial. Tests were performed on motors with intentionally made bearings defects. Chapter 2 introduces the concept of artificial neural networks. It presents...
-
Results of the “DPDT-Auger” Research Project on Screw Displacement Piles
PublicationThe main objective of the “DPDT-Auger” research project was to test the prototype DPDT auger for forming screw displacement piles in the ground (patented in Poland in 2020). An additional aim was to develop design methods and rules for the making of such piles. The augers and piles were first tested on a model scale, and then more extensively in the real scale on experimental field plots. The results found the overall functionality...