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Search results for: LOW TEMPERATURE TESTS
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High-temperature heat pumps – new devices for heat recovery and production of technological steam
PublicationIn the paper, the original high temperature compressor based heat pump with a dry working fluid, i.e. the one in which the slope of saturated vapour line is positive, was presented. The objective of the paper is to investigate the possibility of preparation of technological steam with tempperature 120 C from the waste heat resource at temperature of 50 C. Single comppression cycles as well as cascade systems have been considered...
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The fracture behaviour of notched PMMA specimens under simple loading conditions – Tension and torsion experimental tests
PublicationThis paper presents the results of experimental testing of flat PMMA specimens during uniaxial loading conditions. Two separate tests were conducted: tensile and torsion. The specimens were weakened with V-type edge notches with different root radii: 0.5; 2 and 10 mm. The specimens were made in two thickness variants: 5 and 15 mm. Monotonic tensile and torsion tests were carried out while keeping the averaged strain rate constant,...
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Room temperature depinning of the charge-density waves in quasi-two-dimensional 1T-TaS2 devices
PublicationWe report on the depinning of nearly commensurate charge-density waves in 1T-TaS2 thin films at room temperature. A combination of the differential current–voltage measurements with the low-frequency noise spectroscopy provides unambiguous means for detecting the depinning threshold field in quasi-2D materials. The depinning process in 1T-TaS2 is not accompanied by an observable abrupt increase in electric current—in striking contrast...
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Enhanced method of DS-CDMA low level singnals detection
PublicationThe following article comprises three main parts. The first one generally describes two methods of low level signals detection which are in the interest of this study. The signal spectrum averaging technique is shown as well as the method exploiting averaged spectrum of the signal raised to the power of 2n (nN). Additionally, this section briefly presents proposed enhancements and modifications of these two solutions, which allow...
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On the low-cost design of abbreviated multisection planar matching transformer
PublicationA numerically demanding wideband matching transformer composed of three nonuniform transmission lines (NUTLs) has been designed and optimized at a low computational cost. The computational feasibility of the design has been acquired through the exploitation of low-fidelity NUTL models in most steps of the design procedure and an implicit space mapping optimization engine, providing high accuracy results with only a handful of EM...
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A low-voltage CMOS negative impedance converter for analogue filtering applications
PublicationLow-voltage high-frequency continuous-time filters are still required in many applications and are the subject of continuing research. There are many techniques to realize integrated filters, including OTA C, Opamp RC and MOSFET-C-Opamp. The latter two show high dynamic range at low supply voltage, but their frequency operating range is usually limited to several megahertz. Transconductance filters are dedicated to higher frequencies....
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Effect of sintering temperature on electrochemical performance of porous SrTi1-xFexO3-δ (x = 0.35, 0.5, 0.7) oxygen electrodes for solid oxide cells
PublicationThis work evaluates the effects of the sintering temperature (800 °C, 900 °C, 1000 °C) of SrTi1-xFexO3-δ (x = 0.35, 0.5, 0.7) porous electrodes on their electrochemical performance as potential oxygen electrode materials of solid oxide cells. The materials were prepared by a solid-state reaction method and revealed the expected cubic perovskite structure. After milling, the powders were characterised by a sub-micrometre particle...
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Finite element method simulations of various cases of crash tests with N2/W4/A steel road barrier
PublicationThe subject of this study is performance of N2/W4/A steel road safety barrier investigated in numerical simulations. System was checked under several types of initial conditions, which were assumed basing on the TB11 and TB32 normative crash tests. The main goal of present study is to investigate the relationship between initial conditions (angle and velocity) of the impact and the severity indices (associated to the vehicle occupant) during...
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The influence of solution annealing temperature on the properties of Lean Duplex 2101 welded joints in tubes
PublicationThe article presents a technology of TIG longitudinal welding without filler material (142) of heat exchanger tubes made of Lean Duplex 2101. The results of studies on the effect of heat treatment (solution annealing) on tensile strength, plasticity, delta ferrite and the structure of smooth tubes are shown. It was found, that the change in solution annealing temperature across the tested range has an impact on mechanical properties...
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Low-power device simulator for micro-energy measurement methods testing
PublicationThe paper presents low-power device simulator designed for testing of micro-energy measurement methods. Such kind methods can be used for evaluation of power systems based on Energy Harvesting. The device allows to set the current consumption characteristic over the time, thus making possible playing the role of different types of low-power devices e.g. simulating sensor network node.
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Theoretical study of thermofrictional oscillations due to negative friction-temperature characteristic
PublicationAnalytical study on oscillations of a body on a moving counterbody has been done by assuming imperfect frictional thermal contact and friction that decreases with contact temperature. It has been shown that stick-slip oscillation occurs due to decrease of friction coefficient when the body moves in the opposite direction to the counterbody. Dynamical characteristics, such as conditions for stable sliding and limit cycles, have...
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Use of AMI Meters in the Process of Low Voltage Grid Optimization
PublicationThis is a report of a project involving, inter alia, low voltage grid performance optimization with data from AMI meters . The study was supported with a European UPGRID grant, and executed by a consortium of companies from seven European countries, including Poland .
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Low-Reflection Subgridding
PublicationArtykuł przedstawia technikę umieszczania makromodeli w trójwymiarowej siatce dyskretyzacji metody różnic skończonych. Umożliwia ona łączenie obszarów siatki o różnym kroku dyskretyzacji. Zastosowana prosta interpolacja liniowa wraz z kolokacją pól sąsiadujących ze sobą podobszarów prowadzi do uzyskania małego współczynnika odbicia od obszaru z gęstą siatką.
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Investigations of the Working Process in a Dual-Fuel Low-Emission Combustion Chamber for an FPSO Gas Turbine Engine
PublicationThis investigation is devoted to an analysis of the working process in a dual-fuel low-emission combustion chamber for a floating vessel’s gas turbine. The low-emission gas turbine combustion chamber with partial pre-mixing of fuel and air inside the outer and inner radial-axial swirlers was chosen as the object of research. When modelling processes in a dual-flow low-emission gas turbine combustion chamber, a generalized method...
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The influence of inflation pressure and ambient temperature on the value of the truck tires rolling resistance
PublicationThe articlediscusses the effect of inflation pressure and the ambient temperature on the value of the rolling resistance of truck tires which directly translates into fuel consumption. For this purpose, a series of measurements was made at two ambient temperatures (at 25°C and -15°C), using different pumping pressures.
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Improving the CPX method by specifying reference tyres and including corrections for rubber hardnes and temperature
PublicationRecently completed work in the EU project ROSANNE and in working group ISO/TC43/SC1/WG33 has allowed substantial improvements to measurements made by the Close-Proximity (CPX) method, intended for measurement of noise properties of road surfaces.The paper summarizes the experimental work and describes the conclusions and implementation in ISO/FDIS 11819-2 (CPX method) and in the supporting ISO (draft) Technical Specifications 11819-3...
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Analysis of compressive forces in CFGFT cylindrical pillars and their coatings using laboratory tests and metric spaces
PublicationThe article discusses compressive forces tests in composite-concrete pillars with the use of laboratory active experiment including the factors and properties of materials which have a significant impact on the test results and their repeatability. A polymer composite based on glass fiber reinforced resin with different fiber beam angles (20, 55 and 85) was used as a buffer/coat of the pole. Due to the problems with direct comparison...
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Modified Manganese Phosphate Conversion Coating on Low-Carbon Steel
PublicationConversion coatings are one of the primary types of galvanic coatings used to protect steel structures against corrosion. They are created through chemical reactions between the metal surface and the environment of the phosphating. This paper investigates the impact that the addition of new metal cations to the phosphating reaction environment has on the quality of the final coating. So far, standard phosphate coatings have contained...
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Effect of annealing temperature on slurry erosion resistance of ferritic X10CrAlSi18 steel
PublicationIn the present work, the slurry erosion tests were carried out to investigate the influence of heat treatment on slurry erosion process of ferritic X10CrAlSi18 stainless steel using a slurry pot test rig. X10CrAlSi18 stainless steel was tested in as-received condition and after annealing at three different temperatures: 600°C, 800°C and 1000°C. Degradation of materials due to slurry erosion depends on many factors connected with...
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Local properties of organic coatings close to glass transition temperature
PublicationAcrylic coating applied on copper substrate has been investigated at different temperatures starting from the ambient one up to the level above the glass transition temperature. Its local topographic and electric properties have been examined with the atomic force microscopy (AFM) based approach including dc current mapping and local impedance spectroscopy. The local findings have been compared with the information from global...
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Assessment of the Accuracy of a Virtual Multi-Channel Temperature Measuring Instrument
PublicationThe multi-channel temperature measurement system developed works with NTC thermistors. The article presents the results of theoretical and empirical evaluation of accuracy obtained in measurement channels. The basis for the theoretical assessment is the mathematical model for each of the measurement channels and the characteristics of the system elements included in the circuits of the measurement channel. Two different methods were...
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Optical-Fiber Microsphere-Based Temperature Sensors with ZnO ALD Coating—Comparative Study
PublicationThis study presents the microsphere-based fiber-optic sensor with the ZnO Atomic Layer Deposition coating thickness of 100 nm and 200 nm for temperature measurements. Metrological properties of the sensor were investigated over the temperature range from 100 °C to 300 °C, with a 10 °C step. The interferometric signal was used to monitor the integrity of the microsphere and its attachment to the connecting fiber. For the sensor...
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Low-Cost Automated Design of Compact Branch-Line Couplers
PublicationBranch-line couplers (BLCs) are important components of wireless communication systems. Conventional BLCs are often characterized by large footprints which make miniaturization an important prerequisite for their application in modern devices. State-of-the-art approaches to design of compact BLCs are largely based on the use of high-permittivity substrates and multi-layer topologies. Alternative methods involve replacement of transmission-line...
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Flow Maps and Flow Patterns of R1233zd(E) in a Circular Minichannel at Low, Medium and High Values of Saturation Pressure
PublicationThere is a gap in knowledge regarding the flow pattern of low-boiling working fluids in the range of high saturation temperatures (above 120°C) and medium and high reduced pressures (0.5-0.9). Data are present in the literature for similar values of reduced pressures, but for lower values of saturation temperature. This is due to the existing refrigeration applications of these working fluids. At high values of reduced pressure,...
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Prediction of cast-in-place concrete strength of the extradosed bridge deck based on temperature monitoring and numerical simulations
PublicationThe work is devoted to the implementation of a monitoring system for high performance concrete embedded in the span of an extradosed bridge deck using a modified maturity method augmented by numerical simulations conducted by the authors’ FEM code. The paper presents all research stages of bridge construction and considers the conclusions drawn from the results of laboratory tests, field measurements, and numerical calculations....
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Magneto-thermal convection of low concentration nanofluids
PublicationThe main aim of this paper was to analyze possible utilization of the low concentration nanofluids and the magnetic field to enhance heat transfer. The studied fluids were based on water with an addition of copper particles (40-60 nm diameter). They belonged to the diamagnetic group of materials. As a first attempt to stated target the analysis of enclosure placed in the maximal value of square magnetic induction gradient was carried...
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Novel microstrip low-pass filters with fractal defected ground structures
PublicationIn this study, three microstrip low-pass filters (LPFs) containing fractal-shaped defected ground structures have been designed and manufactured. To improve the performance of microstrip LPF, cascades of inductively coupled fractal resonators have been applied. Simultaneously, to achieve relatively constant microstrip impedance resulting in essentially low reflection losses, a modification of the strip geometry has been introduced....
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Analytical method for calculation of heat source temperature drop for the Organic Rankine Cycle application
PublicationIn the paper presented are considerations on the cooperation of the limited capacity heat source with the Organic Rankine Cycle unit. Usually the heat source providing thermal energy to the Organic Rankine Cycle (ORC) may have twofold characteristics. It can be in the form of a single phase fluid, i.e. as hot exhaust gas or hot liquid, or in some cases it may be available as a phase changing fluid, as for example, technological...
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Polarisation effects in low-energy positron–molecule scattering
PublicationThe UK molecular R-matrix method has been adapted to treat positron collisions from polyatomic targets. A simple empirical enhancement factor which corrects for the underestimation of electron–positron polarisation and correlation effects in the calculations performed with the static-plus-polarization model at low scattering energies is presented. Application of this model to positron scattering from carbon dioxide at energies...
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Characterizing surface and air temperature in the Baltic Sea coastal area using remote sensing techniques and GIS
PublicationEstimation of surface temperature using multispectral imagery retrieved from satellite sensors constitutes several problems in terms of accuracy, accessibility, quality and evaluation. In order to obtain accurate results, currently utilized methods rely on removing atmospheric fluctuations in separate spectral windows, applying atmospheric corrections or utilizing additional information related to atmosphere or surface characteristics...
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Low energy differential elastic electron scattering from trichloromethane
PublicationExperimental differential cross sections for low energy electron scattering from trichloromethane is measured utilizing a crossed electron-molecular beam experiment via the relative flow method, for the incident electron energies in the range of E = 0.5 eV-30 eV and the scattering angles in the range of θ = 10◦ − 130◦ .
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High temperature corrosion of evaporator tubes with thermal sprayed coatings
PublicationDegradation examinations of outer surface of low-emission steam boiler evaporator tubes are presented in the paper. Metallographic evaluation of scale morphology, its micro sites chemical composition analysis and distribution of elements on cross sections have been performed. Water-wall tubes were exposed in steam boiler for up to two years period. Common tubes made of 16Mo3 steel suffered sulphide and molten salts corrosions....
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Magnetosonic Excitation of the Entropy Perturbations in a Plasma with Thermal Conduction Depending on Temperature
PublicationNonlinear excitation of the entropy perturbations by magnetosonic waves in a uniform and infinite plasma model is considered. The wave vector of slow or fast mode forms an arbitrary angle (0 B B ) with the equilibrium straight magnetic field, and all perturbations are functions of the time and longitudinal coordinate. Thermal conduction is the only factor which destroys isentropicity of wave perturbations and causes the nonlinear...
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APPLICATION OF SATELLITE IMAGERY AND GIS TOOLS FOR LAND SURFACE TEMPERATURE ESTIMATION AND VERIFICATION
PublicationLand surface temperature (LST) plays an important role in many land-surface processes on regional as well on global scales. It is also a good indicator of energy flux phenomena and is used as a parameter in various Earth observation related studies. However, LST estimation based on processing and utilisation of satellite derived data constitutes several problems in terms of time limitations, accessibility, atmospheric influence...
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Low Current Transformer Utilizing Co-Based Amorphous Alloys
PublicationMetal oxide surge arresters have been widely used for protection of power system networks against overvoltages due to atmospheric discharges or malfunction of devices connected to the network. During its operation a surge arrester structure is degradated, what can be observed as an increase of a surge arrester leakage current. Paper presents an implementation of a new, high-permeability, Co64Fe4Ni1Si15B14 amorphous alloy as a current...
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Low current transformer utilizing Co-based amorphous alloys
PublicationMetal oxide surge arresters have been widely used for protection of power system networks against overvoltages due to atmospheric discharges or malfunction of devices connected to the network. During its operation a surge arrester structure is degradated, what can be observed as an increase of a surge arrester leakage current. Paper presents an implementation of a new, high-permeability, Co64Fe4Ni1Si15B14 amorphous alloy as a current...
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Intercorrelation between CPTU-DMT tests for sands on the Baltic coast
PublicationNa podstawie badań terenowych opracowano szereg zależności między parametrami uzyskanymi z badania CPTU i DMT w czystych piaskach kwarcowych na Wybrzeżu Bałtyku. Uwzględniono wpływ historii geologicznej złoża oraz prekonsolidacji. Przedstawiono zależności dla piasków normalnie konsolidowanych i prekonsolidowanych. Prekonsolidacja i historia geologiczna bardziej wpływają na wyniki badania DMT niż CPTU. Zaproponowano oszacowanie...
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Measurement accuracy evaluation of transmission line earthings by impulse tests
PublicationUziemienia słupów linii energetycznych powinny być sprawdzane okresowo. Pomiary rezystancji takich uziemień przy pomocy metody niskoczęstotliwościowej wymaga wyłaczania linii i odkręcania przewodów odprowadzających od konstrukcji słupa. Metoda udarowa jest znacznie łatwiejsza w tej aplikacji i nie wymaga wyłaczania linii na czas pomiarów. W pracy oszacowano wpływ uziemień sąsiednich słupów na dokładność pomiarów metodą udarową.
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Fatigue life tests of steel laser-welded sandwich structures
PublicationW publikacji zaprezentowano rezultaty systematycznych badań trwałości zmęczeniowej elementarnych połączeń wykonanych techniką spawania laserowego dla różnych wariantów geometrii złącz. Pokazano uzyskane wyniki i ich aproksymację, porównano uzyskane rezultaty dla różnych geometrii.
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Tests of local strains in steel laser - welded sandwich structure
PublicationW publikacji zaprezentowano rezultaty badań odkształceń w strefie spoiny laserowej konstrukcji sandwich. Pokazano obiekt badań, metodykę i oprzyrządowanie oraz proces rejestracji. Przedstawiono uzyskane wyniki i wnioski z nich wypływające.
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Characteristics of tyre chips-sand mixtures from triaxial tests
PublicationAnaliza parametrów wytrzymałościowych i odkształcalności mieszanek piasku i kawałków zużytych opon. Powtórne użycie tego materiału, odpowiednio przetworzonego na skrawki i elementy o kształcie kołowym pozwala po odpowiednim zmieszaniu z gruntem niespoistym na uzyskanie materiału o zwiększonej wytrzymałości na ścinanie zachowywanej również przy dużych odkształceniach. Analizowano mieszanki o różnej zawartości opon przy naprężeniach...
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Characterization of NiTi SMA in its unusual behaviour in wear tests
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Determination of POPs in environmental matrices – proficiency tests for Polish laboratories
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Rapid Influenza Diagnostic Tests - Indications, Clinical Implications and Usefulness
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Tests of soil-geotextile systems in changeable hydraulic head conditions.
PublicationArtykuł zawiera opis stanowiska badawczego i przeprowadzonych badań filtracji w układzie grunt-geowłóknina w kierunku normalnym do płaszczyzny geosyntetyku.
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Statistical analysis of pressuremeter tests for the north transversal tunnel in Grenoble
PublicationInterpretacja wyników badań presjometrycznych metodą statystyczną. Wartości charakterystyczne. Zastosowano rozkłady normalny, log-normalny, wykładniczy, Weybulla, Gamma, Chiz, Studenta i Pareto. Określono zmienność parametrów geotechnicznych zastosowanych do projektu tunelu i współczynnika bezpieczeństwa w czasie drążenia tunelu.
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Determination of POPs in environmental matrices - proficiency tests for Polish laboratories
PublicationKatedra Chemii Analitycznej Wydziału Chemicznego PG we współpracy ze Stowarzyszeniem RefMat oraz firmą LGC Promochem Sp. z o.o. prowadzi od 2003 roku wieloletni projekt badań biegłości laboratoriów. Celem badań jest określenie biegłości laboratoriów w zakresie oznaczania związków organicznych (anality z grupy PCB, WWA, pestycydy) w próbkach środowiskowych. W ramach projektu przeprowadzono dotychczas trzy badania biegłości dotyczące...
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Scale effect in shaft friction from direct shear tests
PublicationPrzeanalizowano wartości maksymalne tarcia uzyskane w aparacie bezpośredniego ścinania w kontakcie konstrukcja-grunt dla piasków kwarcowych i węglanowych oraz gładkiego i szorstkiego kontaktu. Badania przeprowadzono przy regulowanej sztywności normalnej kontaktu, przy różnej składowej normalnej naprężenia w kontakcie i różnym zagęszczeniu gruntu. Określono efekt skali jako stosunek wartości tarcia mobilizowanego na modelu do tarcia...
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A role of destructive and non-destructive tests in creep damage Identification
PublicationPrzedstawiono wyniki badań mjących zilustrować i określić rolę badań niszczących i nieniszczących w identyfikowaniu degradacji po pełzaniu
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FEM ANALYSIS AND EXPERIMENTAL TESTS OF RIGID RISER HANGING SYSTEM
PublicationThe article presents the analysis, project, and experimental examination of an original rigid riser for Coil Tubing Pipes. The principle of riser operation is based on the use of friction forces. The research included the FEM analysis of the designed riser, calculations of the required bolt tensions, and checking the effect of the clamping force on stress distribution in the pipeline. The results of computer simulation were verified...