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Search results for: TRUSS BUCKLING LOAD
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Nonlocalized thermal behavior of rotating micromachined beams under dynamic and thermodynamic loads
PublicationRotating micromachined beams are one of the most practical devices with several applications from power generation to aerospace industries. Moreover, recent advances in micromachining technology have led to huge interests in fabricating miniature turbines, gyroscopes and microsensors thanks to their high quality/reliability performances. To this end, this article is organized to examine the axial dynamic reaction of a rotating...
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Towards an Understanding of the Stability Assessment of Floating Buildings
PublicationOne of the most important aspects of the design of floating facilities such as ships, floating offshore structures or floating houses is stability. Its impact on both general safety and operational aspects renders it a fundamental consideration already in preliminary design stages. Usually, the concept of sufficient stability of floating buildings is associated with the ability to keep an allowed heel angle and residual freeboard,...
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Centrally Pivoted Tilting Pad Thrust Bearing with Carbon-Based Coated Collar—Experimental Results of Low- and Medium-Speed Operation
PublicationExperimental results of the research on a tilting pad thrust bearing with symmetrical pad support in the conditions of high loads and low speeds are presented in the paper. As described in the literature review, experimental results of tilting pad bearings at low speed/high load regime and transient conditions are rare. Unusual material selection - steel pad against a DLC-type coating on the collar was utilized. Such material combination...
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Ancillary services to grids provided with distributed generation
PublicationThe paper introduces system for utilization of the customer-side generated energy. Additionally system can secure some ancillary services to grids. Those services include: current active filtering, load voltage stabilization and in case of grid voltage faults - uninterruptible load supplying (possible with energy storage device). Presented experimental results confirm flexibility of this arrangement in processes of power delivery...
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Dynamic Response of the Suspended on a Single Cable Footbridge
PublicationThe article presents numerical simulations, dynamic in situ load tests and a structural health monitoring (SHM) system installed in a suspended on a single cable footbridge. Numerical simulations performed prior to construction indicated the possibility of structural dynamics problems, finally confirmed in the course of dynamic test loading. In the dynamic load course the bridge deck developed vibrations displaying accelerations...
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Mathematical Models in Design Process of Ship Bow Thrusters
PublicationThe paper describes an application of simulation models for computer-aided design of ship bow thrusters. Generation of simulation models of ship bow thruster requires development and verifying of mathematical models of system component elements. Using the results of simulation the expert system is able to determine, that the rules of classification societies are met. Design procedures and mathematical models are part of an expert...
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Mathematical Models in Design Process of Ship Bow Thrusters
PublicationThe presentation is about an application of simulation models for computer-aided design of ship bow thrusters. Generation of simulation models of ship bow thruster requires development and verifying of mathematical models of system component elements. Using the results of simulation the expert system is able to determine, that the rules of classification societies are met. Design procedures and mathematical models are part of an...
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Subsoil degradation effect in reliability analysis of the jack-up platform structure
PublicationStructural reliability analysis is considered, by FORM and SORM applied to a certain idealized soil-platform structure interaction problem due to cyclic water wave and wind loads. Wave and wind loads are random variables, whereas dead load is deterministic. Load parameters are typical for storm conditions in the Baltic Sea. The soil-structure interaction is idealized as a set of linear translational and rotational springs. Due...
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Acoustic journal bearing - A search for adequate configuration
PublicationClassical non-contact bearings are already used in a number of specialist applications but there are somespecialist areas where they cannot be used for variety of reasons and acoustic sliding bearings could be an alternative. The paper presents the quest for a configuration of an acoustic journal bearing and shows that the overall shape of the bearing and its geometry are of a vital importance for the load capacity oft he bearing....
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Bearing capacity of the working platform with kinematic method
PublicationBearing capacity of the working platform for heavy tracks was analysed using Distinct Layout Optimization (DLO) method. The platform layer constructed from cohesionless soils is resting on weak cohesive subgrade. Different thickness of the platform, its effective angle of internal friction and undrained shear strength of the soft soil were taken into consideration. Kinematic method permits different failure mechanisms to be analyzed....
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Instructor Presence in Video Lectures: Preliminary Findings From an Online Experiment
PublicationMotivation. Despite the widespread use of video lectures in online and blended learning environments, there is still debate whether the presence of an instructor in the video helps or hinders learning. According to social agency theory, seeing the instructor makes learners believe that s/he is personally teaching them, which leads to deeper cognitive processing and, in turn, better learning outcomes. Conversely, according to cognitive...
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Study of Non-Newtonian biomagnetic blood flow in a stenosed bifurcated artery having elastic walls
PublicationFluid structure interaction (FSI) gained attention of researchers and scientist due to its applications in science felds like biomedical engineering, mechanical engineering etc. One of the major application in FSI is to study elastic wall behavior of stenotic arteries. In this paper we discussed an incompressible Non-Newtonian blood fow analysis in an elastic bifurcated artery. A magnetic feld is applied along x direction. For...
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Effect of pavement roughness and vehicle dynamic loads on decrease of fatigue life of flexible pavements
PublicationDue to the fact that pavement surfaces are not ideally even, dynamic loads of vehicle axles deviate from static loads. Higher dynamic loads contribute to faster pavement distress. The distribution of dynamic loads is similar to normal distribution and can be described by static load and factors DI (dynamic impact) and DLC (dynamic load coefficient). With the deterioration of pavement condition its evenness decreases as well and...
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IDENTIFICATION OF DAMAGES OF TRIBOLOGICAL ASSOCIATIONS IN CRANKSHAFT AND PISTON SYSTEMS OF TWO-STROKE INTERNAL COMBUSTION ENGINES USED AS MAIN PROPULSION IN SEA-GOING VESSELS AND PROPOSAL OF PROBABILISTIC DESCRIPTION OF LOADS AS CAUSES OF THESE DAMAGES
PublicationThe article discusses damages of essential tribological associations in crankshaft and piston systems of large power two-stroke engines used as main engines, which take place during transport tasks performed by those ships. Difficulties are named which make preventing those damages impossible, despite the fact that the technical state of engines of this type is identified with the aid of complex diagnostic systems making use of...
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DESIGN OF THE DUAL CONSTELLATION GPS/GALILEO MOBILE DEVICE FOR IMPROVING NAVIGATION OF THE VISUALLY IMPAIRED IN AN URBAN AREA, POLISH MARITIME RESEARCH
PublicationThe article discusses damages of essential tribological associations in crankshaft and piston systems of large power two-stroke engines used as main engines, which take place during transport tasks performed by those ships. Difficulties are named which make preventing those damages impossible, despite the fact that the technical state of engines of this type is identified with the aid of complex diagnostic systems making use of...
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Thin-walled cross section shape influence on steel member resistance.
PublicationThis work describes why trending thin-walled technology is achieving popularity in steel construction sector. A purpose of this article is to present the influence of the cold-formed element cross-section shape on an axial compression and a bending moment resistance. The authors have considered four different shapes assuming constant section area and thickness. Calculations were based on three different steel grades taking into...
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Distributed VoIP telecommunication system
PublicationIn the paper a distributed VoIP telecommunication system architecture with load balancing is described. Important features of this architecture are the high level of system reliability and the possibility of using lowcost hardware solutions.
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Educational and cognitive aspects of adaptation of nonuse spaces in monumental sacral objects.
PublicationThe area of attics and towers in historic churches in Europe are yet quite inaccessible places for visitors, shrouded in the atmosphere of mysticism, hiding many secrets. Introduction of the new public function into the non-used zones of the monumental sacral objects has many aspects including educational and cognitive ones which are discussed in the following article. The article indicates items that can be found in the zone above...
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The reasons of considarable deflections of roof trusses in engineering analysis
PublicationThe aim of the paper is to present an unconventional analysis of deformations of roof trusses of an exhibition pavilion. Structure of the main hall of the pavilion consists of repeatable span frames with steel pillars made of I-sections, fastened in the foundations and hinged supporting roof girders. The roof trusses, completed in steel construction, have undergone considerable permanent deflections. Deformations of the lower chord...
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Tensile strength of a weave tendon suture using tendons of different sizes
PublicationThis study compared the maximum load, stress, elongation at failure and the mode of failure of three kinds of tendons most frequently used for tendon grafting and tendon transfers, using the Pulvertaftweave suture.
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Implementacja pomierzonych imperfekcji geometrycznych powłokicylindrycznej do modelu obliczeniowego
PublicationThis paper presents the method of implementation of the geometrical imperfections used by the author during the experimental and numerical research into the load-carrying capacity of cylindrical steel shells subjected to uniform circumferential compression.
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Prediction of Pile Shaft Capacity in Tension Based on Some Direct CPT Methods—Vistula Marshland Test Site
PublicationThis paper presents different CPT methodologies for the prediction of the pile shaft resistance in tension on the example of three reference screw piles of the Jazowa test site in Poland. The shaft capacity was estimated based on the cone resistance, sleeve friction and CPT excess pore water pressure. Three piles with diameter 0.4 m and the length varied from 8 m to 14.6 m were subjected to static load tests in tension. Their...
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Optimization of the Relative Humidity of Reactant Gases in Hydrogen Fuel Cells Using Dynamic Impedance Measurements
PublicationWater management is a key factor affecting the efficiency of proton exchange membrane fuel cells (PEMFCs). The currently used monitoring methods of PEMFCs provide limited information about which processes or components that humidity has a significant impact upon. Herein, we propose the use of a novel approach of impedance measurements using a multi-sinusoidal perturbation signal, which enables impedance measurements under dynamic...
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Ultimate compressive strength assessment of uncleaned and cleaned corroded plates with locked crack
PublicationThe work presented here investigates the structural response of cleaned corroded plates, subjected to compressive load in the presence of a locked crack, where the change of mechanical properties as a result of corrosion development and the cleaning process is also accounted for. A Finite Element model for assessing the compressive strength, considering geometric and material nonlinearities, is developed, and the analysed plates...
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Modeling of Common Mode Currents Induced by Motor Cable in Converter Fed AC Motor Drives
PublicationInvestigation of conducted EMI generation in AC motor fed by pulse width modulated frequency converters requires to consider parasitic capacitances in converters, motor windings and feeding cables to be taken into account. Motor voltage transients and related common mode currents are significantly correlated with resonance effects occurring in load circuits. An analysis of frequency converter load impedance-frequency characteristics...
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Performance of the PEM fuel cell module. Part 2. Effect of excess ratio and stack temperature
PublicationThe paper describes a fuel cell based system performance under different thermal conditions. The system could be fed with bottled hydrogen or with very high purity hydrogen obtained from reforming of methanol. The system is based on two fuel cell units (1.2 kW each, produced by Ballard Power Systems Inc. and called Nexa), DC/DC converter, DC/AC inverter, microprocessor control unit, load unit, bottled hydrogen supply system and...
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Selected Stability Problems of Thin-Walled Columns and Beams
PublicationThe article reviews a number of papers in the light of buckling analy- sis of thin-walled columns and beams. Stability of thin-walled columns and beams are considered a vital engineering science issue in both historical and present-day approaches. The paper refers to the recent authors’ works of the 2012–2019 period, published in leading journals. Similar review of stability problems of thin-walled structures developed at Gdansk...
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Simplified stability analysis of steel cylindrical silos with corrugated walls and vertical columns
PublicationIn the paper a simplified stability analysis of steel cylindrical silos composed of corru¬gated walls and vertical open-sectional columns was proposed. The whole 3D silo was modeled as a single column resting on elastic foundation provided by the silo walls. In proposed formula for the calculation of the foundation stiffness the curvature of the silo walls was taken into account. Three different analyses were carried out using...
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Air journal bearing utilizing near-field acoustic levitation: stationary shaft case
PublicationResults of a study to examine a unique idea of self-levitating journal bearing are presented in this paper. the idea represents a radical departure from the current bearing technology. it utilisesacoustic levitation, which relies on the sound energy radiated by an object supporting a load. acoustic levitation has been demonstrated to support loads of up to 10 kg. in order to support a load theacoustic wave emitted by the radiating...
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Induction motor control application in high-speed train electric drive
PublicationThe chapter presents an application of induction motor mechanical speed and load torque observers in high-speed train drives. The observers are applied for a 1.2-MW electric drive with an induction motor. The goal of using such observers is to utilize computed variables for diagnostic purposes of speed sensors and torque transmission system. The concept of diagnostic system is presented in this paper, and proper criteria are proposed....
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Bending analysis of functionally graded nanoplates based on a higher-order shear deformation theory using dynamic relaxation method
PublicationIn this paper, bending analysis of rectangular functionally graded (FG) nanoplates under a uniform transverse load has been considered based on the modified couple stress theory. Using Hamilton’s principle, governing equations are derived based on a higher-order shear deformation theory (HSDT). The set of coupled equations are solved using the dynamic relaxation (DR) method combined with finite difference (FD) discretization technique...
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Tribological Properties of Thermoplastic Materials Formed by 3D Printing by FDM Process
PublicationThe dataset entitled 3D printed ABS thermoplastic vs. steel. Dry sliding wear test in constant load & velocity ring on flat configuration. Test parameters: print layer thickness and orientation. Test symbol: 019_h_4 contains: the time base (expressed in seconds and minutes), the friction torque for sliding friction, rotational velocity of the counter – specimen (velocity of sliding), friction coefficient, load in the friction contact...
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Multiple reference frame theory in the synchronous generator model considering harmonic distortions caused by nonuniform pole shoe saturation
PublicationThe paper describes a synchronous generator model developed based on the multiple reference frame theory. The main physical phenomena included in the model are the machine armature non-sinusoidal voltage waveform and the influence of armature current in load conditions on the armature voltage waveform higher harmonic components. The modified multiple reference frame theory model is proposed. In this modified theory model the field...
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REINFORCED CONCRETE SUPPORTING CONSTRUCTION OF THE STADIUM COVER FOR EURO 2012 IN GDAŃSK
PublicationIn the article structural issues that connected with the reinforced concrete supporting construction of the stadium roofing for EURO 2012 in Gdańsk were described. In the first part of the article the concept of stadium foundation were described. In the second the static - strength analysis for two variants fastening together individual foundation elements were made. The two assumed geometrically different concept of foundation...
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The impact of the distribution network reconfiguration on active power losses: Selected issues of UPGRID project realization
PublicationThe dynamic development of smart grids allows the use of remote controllable switches to change the configuration of the distribution network. The paper discusses the impact of the distribution system reconfiguration on active power losses, taking into account the typical daily load profiles. Based on modified IEEE 33-bus test distribution system the article presents the method of selection the appropriate sensitivity factor and...
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Hybrid geothermal-fossil power cycle analysis in a Polish setting with a focus on off-design performance and CO2 emissions reductions
PublicationGrowing demand for electricity due to economic development contributes to increased greenhouse gas production, especially CO2. However, emissions can be limited by enhancing the efficiency of primary energy conversion, such as integrating geothermal energy into coal-fired power plants. Therefore, this paper proposes replacing conventional feed-water heaters with geothermal preheaters to create a hybridized system. This study was...
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Prediction of fracture toughness in fibre-reinforced concrete, mortar, and rocks using various Machine learning techniques
PublicationMachine Learning (ML) method is widely used in engineering applications such as fracture mechanics. In this study, twenty different ML algorithms were employed and compared for the prediction of the fracture toughness and fracture load in modes I, II, and mixed-mode (I-II) of various materials, including fibre-reinforced concrete, cement mortar, sandstone, white travertine, marble, and granite. A set of 401 specimens of “Brazilian...
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Instrumented end notched flexure - Crack propagation and process zonemonitoring Part II: Data reduction and experimental
PublicationA mode II instrumented end notched flexure three point bending (ENF) adhesion test is described. The adhesive joint consists of two aluminium alloy (AW7075-T6) plates bonded with a structural epoxy adhesive (Hysol EA 9395™). Strain gauges are attached to the outer surface (backface) of the substrates in the lengthwise direction to measure local surface strain during crack propagation. Simultaneously, load/displacement measurements...
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Some Aspects of Shear Behavior of Soft Soil–Concrete Interfaces and Its Consequences in Pile Shaft Friction Modeling
PublicationThis paper examines the stiffness degradation and interface failure load on soft soil–concrete interface. The friction behavior and its variability is investigated. The direct shear tests under constant normal load were used to establish parameters to hyperbolic interface model which provided a good approximation of the data from instrumented piles. Four instrumented piles were used to obtain reference soil–concrete interface behavior....
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Lagrangian model of an isolated dc-dc converter with a 3-phase medium frequency transformer accounting magnetic cross saturation
PublicationThis article presents a nonlinear equivalent circuit model of an isolated dc-dc converter with a 3-phase medium frequency transformer. The model takes into account the magnetic cross saturation of the 3-phase core-type magnetic circuit. The model is suitable in detailed electromagnetic transient simulations of power systems involving isolated dc-dc converters. The model is developed using the Lagrange energy method. It involves...
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Investigation on Mode I Fracture Behavior of Hybrid Fiber-Reinforced Geopolymer Composites
PublicationRecent reports in the literature have shown that fber-reinforced geopolymer composites (FRGC) made with monofbers exhibit a signifcant enhancement in fracture energy. However, many aspects of the fracture performance of hybrid fberreinforced geopolymer composites (HFRGC) remain largely unexploited, and these are predominant for the structures. For the frst time, the mode I fracture energy of HFRGC is investigated. The mode I behavior...
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Prediction of pile shaft capacity in tension based on some direct CPT methods – Vistula Marshland test site
PublicationThis paper presents different CPT methodologies for the prediction of the pile shaft resistance in tension on the example of three reference screw piles of the Jazowa test site in Poland. The shaft capacity was estimated based on the cone resistance, sleeve friction and CPT excess pore water pressure. Three piles with a diameter of 0.4 m and the length...
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Dynamic mass measurement in checkweighers using a discrete time-variant low-pass filter
PublicationConveyor belt type checkweighers are complex mechanical systems consisting of a weighing sensor (strain gauge load cell, electrodynamically compensated load cell), packages (of different shapes, made of different materials) and a transport system (motors, gears, rollers). Disturbances generated by the vibrating parts of such a system are reflected in the signal power spectra in a form of strong spectral peaks, located usually in...
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A Comparison of the Efficiency of Deammonification under Different Aeration Strategies in a Laboratory-Scale Sequencing Batch Reactor
PublicationAn important source of nitrogen load entering the biological part of wastewater treatment plants (WWPTs) is derived from the anaerobic sludge digestion processes. Sludge digestion liquors constitute only 1-2% of the inflow to the plant, but the load of nitrogen directed with them to the main stream may be as high as 10-20% of the total nitrogen load. Therefore, numerous studies have focused on treatment of sludge digestion liquors...
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Simulation Results of Dynamic Capacity Reallocation in Hierarchical Cell Structure of UMTS Network
PublicationIn the paper simulation results of dynamic capacity reallocation between different layers of hierarchical cell structure of UMTS network has been described. This approach for load management seems to be useful for improving the resource utilization perfmorance.
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Direct design of Controlled Modulus Columns (CMC) based on in-situ testing
PublicationIn this paper, the serviceability limit state and bearing capacity of tension screw displacement piles were analyzed using the results of static pile load tests, carried out on the test plot near the Elbląg city, and field, and laboratory tests. The paper presents the methodology of determining the pile load-settlement curve using different types of t-z transfer functions. The new method of constructing the pile load-settlement...
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Influence of the particle size of carbonate-siliceous rock on the efficiency of phosphorous removal from domestic wastewater
PublicationtThe aim of the study was to determine the influence of the particle size of carbonate–silica rock (opoka)used in rock filters on the efficiency of phosphorus removal from domestic wastewater. The investigationswere carried out in a laboratory using a model consisting of three vertical flow filters with carbonate–silicarock of different particle sizes (G1= 1–2 mm; G2= 2–5 mm; G3= 5–10 mm). The tested rock was subjectedto decarbonising...
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Vibration monitoring of structures in the light of the Polish and international requirements
PublicationThe paper concerns the wide range of strategies used to protect structures against man-made dynamic excitation. The most popular approaches applied worldwide are compared, and the main differences and similarities are summarized. The literature studies are supported by the results of the measurements performed on different types of real structures, which are sensitive and insensitive to the dynamic load. To make the conclusions...
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Non-Salient Brushless Synchronous Generator Main Exciter Design for More Electric Aircraft
PublicationThis paper presents a prototype of high speed brushless synchronous generators (BSG) design for the application in autonomous electric power generation systems (e.g., airplane power grid). Commonly used salient pole field of the main generator part of BSG was replaced with a prototype non-salient pole field. The main objective of the research is an investigation into the advantages and disadvantages of a cylindrical field of the...
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MONITORING SYSTEM OF THE ROAD EMBANKMENT
PublicationThe paper presents the analysis of the monitoring system of the embankment supported on concrete columns and overlaid by a load transfer platform with the embedded steel grid. This field investigation was to study the complex interaction among the columns, the load transfer platform layer, and steel grid via in situ measurements during erection and live loading of the embankment. The study was focused on the behaviour of steel...