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1

Experimental validation of a CFD model of a ground heat exchanger with slinky coils

Grzywacz Robert, Teper Mikołaj

Polish Journal of Chemical Technology

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2024

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Vol. 26, nr 2

86--91

EN

Rising energy prices have increased the popularity of many renewable energy sources including heat pumps. In the case of ground heat pumps research related to the analysis of the operation and selection of ground heat exchangers as a heat source are insufficient. With this in mind, on the operation of the horizontal slinky coil heat exchanger research work has been undertaken. As a research tool, the Computational Fluid Dynamics has been used. To check the adequacy of the CFD model, a validation of the model was carried out using the results of research on a real heat exchanger. Comparison was made: values of ground temperatures, outlet temperatures from the exchanger, and heat flux exchanged by the heat exchanger. In the opinion of the authors, the validation of the CFD model was successful.

2

Application of the KUKA KUBE test-bed for the hardware-in-the-loop validation of the space manipulator control system

Wojtunik Mateusz, Łuczak Piotr, Rybus Tomasz, Granosik Grzegorz

Artificial Satellites : Journal of Planetary Geodesy

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2023

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Vol. 58, Special Issue 1

231--248

EN

The on-ground validation of control systems designed for manipulators working in orbit is very difficult due to the necessity of simulating the microgravity environment on Earth. In this paper, we present the possibilities of utilising the KUKA KUBE test-bed with industrial robots to experimentally verify space systems using hardware-in-the-loop tests. The fixed-base KUKA industrial robot is operated in gravitational environment, while the space system model plant is solved in real time parallel to on-ground experiment. The test-bed measurements are the input of the model plant, and the output of the model is treated as an input for the industrial robot actuation. In the performed experiment, the control system based on the Dynamic Jacobian is validated. The desired point that is reached by the manipulator’s endeffector is constant in the simulated environment and moving with respect to the test-bed frame. The position of the space manipulator’s end-effector is calculated by evaluating dynamics of the satellite in real-time model. The results show that the control system applied to the KUKA robot works correctly. The measurements from the torque sensors mounted in KUKA robot’s joints are in accordance with the simulation results. This fact enhances the possibilities of gravity compensation, thus simulating microgravity environment on the test-bed.

3

Effects of rotation on transient fluid flow and heat transfer through a curved square duct: the case of negative rotation

Hasan Mohammad Sanjeed, Mollah Md. Tusher, Kumar Dipankar, Mondal Rabindra Nath, Lorenzini Giulio

International Journal of Applied Mechanics and Engineering

|

2021

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Vol. 26, no. 4

29--50

EN

The fluid flow and heat transfer through a rotating curved duct has received much attention in recent years because of vast applications in mechanical devices. It is noticed that there occur two different types of rotations in a rotating curved duct such as positive and negative rotation. The positive rotation through the curved duct is widely investigated while the investigation on the negative rotation is rarely available. The paper investigates the influence of negative rotation for a wide range of Taylor number [...] when the duct itself rotates about the center of curvature. Due to the rotation, three types of forces including Coriolis, centrifugal, and buoyancy forces are generated. The study focuses and explains the combined effect of these forces on the fluid flow in details. First, the linear stability of the steady solution is performed. An unsteady solution is then obtained by time-evolution calculation and flow transition is determined by calculating phase space and power spectrum. When Tr is raised in the negative direction, the flow behavior shows different flow instabilities including steady-state, periodic, multi-periodic, and chaotic oscillations. Furthermore, the pattern variations of axial and secondary flow velocity and isotherms are obtained, and it is found that there is a strong interaction between the flow velocities and the isotherms. Then temperature gradients are calculated which show that the fluid mixing and the acts of secondary flow have a strong influence on heat transfer in the fluid. Diagrams of unsteady flow and vortex structure are further sketched and precisely elucidate the curvature effects on unsteady fluid flow. Finally, a comparison between the numerical and experimental data is discussed which demonstrates that both data coincide with each other.

4

Modelowanie i walidacja wytrzymałościowa kompozytowej skorupy nośnej fotela kolejowego

Gołębiowski Łukasz, Siwek Marcin, Ciesielski Marcin, Zagórski Andrzej, Krauze Sławomir, Majewski Radosław

Problemy Kolejnictwa

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2020

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Z. 189

7--16

PL

Przedmiotem prac modelowych i badań doświadczalnych jest kompozytowa skorupa nośna fotela kolejowego. Zaprojektowano kształt geometryczny i strukturę materiałową konstrukcji oraz dobrano materiały. Do budowy skorupy wykorzystano kompozyty włókniste o osnowie polimerowej (kompozyty FRP – Fiber Reinforce Polimer), które są lżejsze w porównaniu ze stalą i jednocześnie zapewniają odpowiednie standardy z zakresu wytrzymałości i bezpieczeństwa. Opracowano obliczeniowy model skorupy i przeprowadzono analizę wytrzymałościową zgodnie z wytycznymi branżowej normy oraz hipotezami wytrzymałościowymi dotyczącymi kompozytów FRP. Obliczenia przeprowadzono za pomocą oprogramowania ANSYS (Ansys Composite PrepPost), bazującego na metodzie elementów skończonych. W artykule przedstawiono analizę wytrzymałościową zoptymalizowanego modelu kompozytowej skorupy nośnej fotela. Na podstawie wytycznych z prac modelowych wytworzono model fizyczny (walidacyjny), w technologii laminowania próżniowego na gorąco. Walidację doświadczalną modelowania z wynikiem pozytywnym przeprowadzono na stanowisku badawczym firmy S.Z.T.K. TAPS – Maciej Kowalski.

5

Modelling and Validation of the Composite Shell of a Train Seat

Gołębiowski Łukasz, Siwek Marcin, Ciesielski Marcin, Zagórski Andrzej, Krauze Sławomir, Majewski Radosław

Problemy Kolejnictwa

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2020

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Z. 189

75--84

EN

The subject of the modelling work and the conducted experiments is the composite shell of a train seat. The activities carried out involved designing the geometry, planning the material structure, and selecting the materials to be used. The shell was built using polymer matrix fibrous composites (i.e. FRP – Fibre Reinforced Polymer – composites), which are lighter than steel and comply with the relevant standards for strength and safety at the same time. This was followed by creating a computational model for the shell and conducting a strength analysis in accordance with the guidelines of the relevant industry standard and strength hypotheses adopted for FRP composites. The calculations were conducted using ANSYS Composite PrepPost software based on the finite element method. The article offers a strength analysis of an optimised composite shell of a train seat. Based on the guidelines obtained as a result of the conducted modelling work, a physical prototype (validation model) of the seat was created. Hot vacuum lamination technology was applied in the production process. The experimental validation of the model, producing a positive result, was conducted using a test stand owned by S.Z.T.K. TAPS – Maciej Kowalski.

6

Fault tolerant multicontrollers for nonlinear systems: A real validation on a chemical process

Mejdi Sondess, Messaoud Anis, Ben Abdennour Ridha

International Journal of Applied Mathematics and Computer Science

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2020

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Vol. 30, no. 1

61--74

EN

An active sensor fault tolerant controller for nonlinear systems represented by a decoupled multimodel is proposed. Active fault tolerant control requires accurate fault estimation. Thus, to estimate both state variables and sensor faults, a discrete unknown input multiobserver, based on an augmented state multimodel, is designed. The multiobserver gains are computed by solving linear matrix inequalities with equality constraints. A multicontrol strategy is proposed for the compensation of the sensor fault and recovering the desired performances. This strategy integrates a bank of controllers, corresponding to a set of partial models, to generate a set of control laws compensating the fault effect. Then, a switching strategy between the generated local control laws is established in order to apply the most suitable control law that tolerates the fault and maintains good closed loop performances. The effectiveness of the proposed strategy is proven through a numerical example and also through a real time application on a chemical reactor. The obtained results confirm satisfactory closed loop performance in terms of trajectory tracking and fault tolerance.

7

Numerical modelling of post-ground subsystem in road safety barrier crash tests

Klasztorny Marian, Nycz Daniel Bronisław, Dziewulski Paweł, Gieleta Roman, Stankiewicz Michał, Zielonka Karol

Engineering Transactions

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2019

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Vol. 67, iss. 4

513--534

EN

A new analytical algorithm for determining the elastoplastic parameters for soft, medium and hard plastic cohesive soils, corresponding to *MAT_005_SOIL_AND_FOAM material model available LS-Dyna FE code, was formulated. The numerical modelling of the post-soil subsystem, applicable in the modelling of road safety barrier crash tests using this material model of the roadside dehydrated ground, was developed. The methodology was presented on the example of a Sigma-100 steel post partly driven into the soil and subjected to a static flexural-torsional test using a horizontal tensioned rope. The experimental validation of the numerical modelling and simulation was carried out on the testing site at the Automotive Industry Institute, Warsaw, Poland. The simulations were carried out for numerical models with soil solid elements with reduced integration (ELFORM_1) and full integration (ELFORM_2). The simulation results are in the form of graphs of the rope tension vs. displacement of the upper measurement point of the post and in the form of deformation of the post-soil system. It was shown that the validation experiment was carried out on the post embedded in hydrated soft plastic cohesive soil.

8

Experimental Validation of Riveting Process Fe Simulation

Wronicz W.

Fatigue of Aircraft Structures

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2018

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Iss. 10

63--72

EN

Rivets are critical areas in metal airframes from the fatigue point of view. Fatigue behaviour of riveted joints depends strongly on the residual stress system around the rivet holes. The both most convenient and most common method of determining these stresses is the Finite Element (FE) analyses. The validation of models used is necessary to ensure the reliability of results. This paper presents the validation process of the riveting FE simulations for the universal and the countersunk rivets. At first, the material model of the rivets was validated with the use of the force-displacement curves of the press stamp obtained experimentally. Because of the displacement measurement method, it was necessary to take into account the flexibility of the stand. After that, good correlation between the numerical simulations and the experiment was obtained for both rivet types. At the second stage, strains around driven heads measured with the use of strip gauge patterns were compared with the results of the FE simulations. Quite good correlation was obtained for the countersunk rivet. In the case of the universal rivet, the numerical results are significantly higher values than the measured ones. Differences in correlation of the experiments and FE simulations for the analysed rivet types probably result from material differences of the rivets.

9

Enhanced modelling and numerical testing of GFRP composite box beam with adhesive joints

Klasztorny M., Nycz D. B., Zając K. P.

Composites Theory and Practice

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2018

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R. 18, nr 4

217--226

EN

The subject of the experiment and numerical research is a simply-supported thin-walled box beam with a span of 2.00 m, created by gluing two composite GFRP shells. The beam was subjected to a three-point bending test controlled by displacement in the range from 0 to 300 mm. An experimental bending test, numerical modelling and simulations of this test as well as validation of the modelling and simulation were carried out. In comparison with the authors’ previous publication, adjustments and enhancements include: correction of the GFRP material constants and friction coefficients; testing the key numerical parameters of the geometrically and physically non-linear task, i.e. an iteration step in the implicit algorithm, a convergence tolerance coefficient, FE mesh density; testing the use of the Glue contact option in the MSC.Marc FE code for modelling adhesive joints; quasi-optimization of the ply sequence with the maximum load bearing capacity as the objective function. The parameters and options of numerical modelling and simulation of glued composite shells in the MSC.Marc system were determined, useful for detailed design calculations of composite FRP structures.

PL

Przedmiotem badań numerycznych jest cienkościenna belka skrzynkowa swobodnie podparta, o rozpiętości 2.00 m, utworzona przez sklejenie dwóch powłok kompozytowych GFRP ze sobą na całej długości belki. Belkę poddano próbie trójpunktowego zginania sterowanego przemieszczeniem w zakresie od 0 do 300 mm. Przeprowadzono eksperymentalną próbę zginania, modelowanie numeryczne i symulacje tej próby oraz walidację modelowania i symulacji. W porównaniu z poprzednią pracą autorów (Composites Theory and Practice, 2015) korekty i ulepszenia obejmują: korektę stałych materiałowych kompozytu GFRP i współczynników tarcia, testowanie parametrów numerycznych zadania nieliniowego geometrycznie i fizycznie, tj. krok iteracyjny w algorytmie implicite, współczynnik tolerancji zbieżności, gęstość siatki elementów skończonych, testowanie opcji Glue contact w systemie MSC.Marc do modelowania spoin klejowych, quasi-optymalizacja sekwencji warstw z funkcją celu w postaci maksimum nośności belki przy zginaniu. Wyznaczono parametry i opcje modelowania numerycznego i symulacji kompozytowych powłok sklejanych z użyciem systemu MSC.Marc, przydatne do szczegółowych obliczeń projektowych konstrukcji z kompozytów FRP.

10

Search for the most useful geometry of an acoustic journal bearing

Gawarkiewicz R.

Tribologia

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2017

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nr 3

57--66

EN

Computer simulations of a number of journal bearing’s geometries utilising acoustic levitation were carried out. The choice of the best geometry depended on the ability of a deformed shape, created by piezo-electric elements, to facilitate squeeze film ultrasonic levitation, and also to create three evenly distributed diverging aerodynamic gaps. Deformations of analysed variants of the bearing’s shape were generated by numerical simulations utilising the finite element method. For the chosen shapes of geometry, prototype bearings were made and their usefulness verified experimentally. As a result, the bearing with the highest load carrying capacity was identified.

PL

Przeprowadzono analizę użyteczności szeregu geometrii panwi łożyska poprzecznego wykorzystującego lewitację akustyczną. Wybór najlepszego z przeanalizowanych rozwiązań zależał od zdolności do uzyskiwania kształtu jego powierzchni czynnej sprzyjającego powstaniu ponaddźwiękowej lewitacji akustycznej (wykorzystującej efekt „wyciskania” filmu smarnego), a także umożliwiającego tworzenie zbieżnych równomiernie obwodowo rozmieszczonych szczelin smarnych, które były warunkiem powstawania filmu aerodynamicznego. Kształt części czynnej łożyska zależał od jej deformacji wywoływanej elementami piezoelektrycznymi. Spodziewane deformacje poszczególnych wariantów panwi otrzymywano na drodze symulacji numerycznych wykorzystujących metodę elementów skończonych. Dla wytypowanych geometrii wykonano prototypy łożysk, których przydatność zweryfikowano podczas badań doświadczalnych. Ostatecznie udało się uzyskać postacie panwi łożyskowej o bardzo dużej stabilności pracy, nawet w warunkach impulsowego obciążenia poprzecznego.

11

Discussion on Usability of the Niyama Criterion for Porosity Predicting in Cast Iron Castings

Ignaszak Z.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 3

196--204

EN

The paper refers to previous publications of the author, focused on criteria of casting feeding, including the thermal criterion proposed by Niyama. On the basis of this criterion, present in the post-processing of practically all the simulation codes, danger of casting compactness (in the sense of soundness) in form of a microporosity, caused by the shrinkage phenomena, is predicted. The vast majority of publications in this field concerns shrinkage and feeding phenomena in the cast steel castings – these are the alloys, in which parallel expansion phenomenon does not occur as in the cast irons (graphite crystallization). The paper, basing on the simulation-experimental studies, presents problems of usability of a classic, definition-based approach to the Niyama criterion for the cast iron castings, especially of greater massiveness, for prediction of presence of zones of dispersed porosity, with relation to predictions of the shrinkage type defects. The graphite expansion and its influence on shrinkage compensation during solidification of eutectic is also discussed.

12

Non-linear viscoelastic constitutive model for bovine cortical bone tissue

Pawlikowski M., Barcz K.

Biocybernetics and Biomedical Engineering

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2016

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Vol. 36, no. 3

491--498

EN

In the paper a constitutive law formulation for bovine cortical bone tissue is presented. The formulation is based on experimental studies performed on bovine cortical bone samples. Bone tissue is regarded as a non-linear viscoelastic material. The constitutive law is derived from the postulated strain energy function. The model captures typical viscoelastic effects, i.e. hysteresis, stress relaxation and rate-dependence. The elastic and rheological constants were identified on the basis of experimental tests, i.e. relaxation tests and monotonic uniaxial tests at three different strain rates, i.e. [...] = 0:1 min_1, [...] = 0:5 min_1 and [...] = 1:0 min_1. In order to numerically validate the constitutive model the fourth-order stiffness tensor was analytically derived and introduced to Abaqus® finite element (FE) software by means of UMAT subroutine. The model was experimentally validated. The validation results show that the derived constitutive law is adequate to model stress–strain behaviour of the considered bone tissue. The constitutive model, although formulated in the strain rate range [...] = 0:1-1:0 min_1, is also valid for the strain rate values slightly higher than [...] = 1:0 min_1. The work presented in the paper proves that the formulated constitutive model is very useful in modelling compressive behaviour of bone under various ranges of load.

13

Modelling and numerical simulations of a TB51 road crash test using a simplified coach model

Dziewulski P.

Archiwum Motoryzacji

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2016

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Vol. 72, nr 2

29--42

EN

The paper proposes a methodology of a TB51 virtual crash test on the example of the selected bridge protective barrier, using a simplified coach model. In simulations of crash tests, the nonlinear, explicit finite element code LS-Dyna v971 was used. The simulation results corresponding to the simplified model were compared with the simulation results for a quasi-accurate model and the experimental crash test results. It was shown that the simplified vehicle model can be used in tests certifying a barrier modified in relation to the certified reference barrier.

PL

W pracy zaproponowano metodologię wirtualnego badania zderzeniowego TB51 wg normy PN-EN 1317 na przykładzie wybranej mostowej bariery ochronnej, z zastosowaniem uproszczonego modelu autobusu. Celowo zrezygnowano z wpływu zawieszenia, tarcia kół o nawierzchnię, obrotu wokół poziomych osi centralnych pojazdu oraz maksymalnie uproszczono strefy zgniotu. Celem jest skrócenie symulacji i umożliwienie szybkiej kalibracji modelu pojazdu. Takie podejście pomoże również jednostkom certyfikującym w ocenie wyników ze względu na uproszczenie i ujednolicenie pojazdów używanych w symulacjach uderzenia w barierę. Wyniki symulacji odpowiadające modelowi uproszczonemu porównano z wynikami symulacji dla modelu quasi-dokładnego oraz z wynikami eksperymentalnego testu zderzeniowego. Wykazano, że uproszczony model pojazdu może być zastosowany do badań certyfikujących bariery zmodyfikowanej w stosunku do bariery referencyjnej mającej certyfikat. Do symulacji testów zderzeniowych zastosowano nieliniowy jawny kod Metody Elementów Skończonych LS-Dyna v971.

14

Analysis of radiative heat transfer impact in cross-flow tube and fin heat exchangers

Hanuszkiewicz-Drapała M., Bury T., Widziewicz K.

Archives of Thermodynamics

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2016

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Vol. 37, no. 1

99--112

EN

A cross-flow, tube and fin heat exchanger of the water – air type is the subject of the analysis. The analysis had experimental and computational form and was aimed for evaluation of radiative heat transfer impact on the heat exchanger performance. The main element of the test facility was an enlarged recurrent segment of the heat exchanger under consideration. The main results of measurements are heat transfer rates, as well as temperature distributions on the surface of the first fin obtained by using the infrared camera. The experimental results have been next compared to computational ones coming from a numerical model of the test station. The model has been elaborated using computational fluid dynamics software. The computations have been accomplished for two cases: without radiative heat transfer and taking this phenomenon into account. Evaluation of the radiative heat transfer impact in considered system has been done by comparing all the received results.

15

Modelling, simulation and validation of bending test of box segment formed as two composite shells glued together

Klasztorny M., Nycz D., Cedrowski M.

Composites Theory and Practice

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2015

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R. 15, nr 2

88--94

EN

The present experimental and numerical research is focused on a box composite beam, so-called a validation segment, consisting of two vinylester/glass shells glued together. The top shell has a hat cross-section, whereas the bottom one is flat. The shells are glued together at two horizontal contact strips. The validation segment reflects the central part of the cross- and longitudinal-section of a box composite superstructure of a footbridge designed by the authors. The dimensions of the cross-section and the number of fabric layers in the validation segment are decreased twice in comparison with the footbridge superstructure. Moreover, the composite beam was rotated by 180° in relation to the footbridge. The validation segment is 2.35 m long, and the cross-section overall dimensions are 0.60 m × 0.26 m (width×height). The laminate components, glue and manufacturing technology of the validation segment are the same as for the composite footbridge. The study develops a methodology for numerical modelling and simulation by the Finite Element Method of box composite girders formed as two composite shells glued together. The methodology is developed in reference to the validation segment which is subjected to the 3-point bending test with shear. Experimental validation of the modelling and simulation was carried out for the basic case of new laminates at 20°C. FE computer code MSC.Marc 2010 was used for the numerical modelling and simulation.

PL

Przedmiotem badań eksperymentalnych i numerycznych jest belka kompozytowa o przekroju skrzynkowym, zwana segmentem walidacyjnym, składająca się z dwóch sklejonych ze sobą powłok kompozytowych winyloestrowo-szklanych. Powłoka górna ma przekrój kapeluszowy, a powłoka dolna jest płaska. Powłoki są sklejone ze sobą na dwóch poziomych pasach kontaktu. Segment walidacyjny odwzorowuje środkową część przekroju poprzecznego i podłużnego konstrukcji nośnej kompozytowej skrzynkowej kładki dla pieszych zaprojektowanej przez autorów. Wymiary przekroju poprzecznego oraz liczba warstw tkanin w laminatach segmentu walidacyjnego są dwukrotnie mniejsze w porównaniu z konstrukcją nośną kładki. Ponadto, segment belkowy obrócono o 180° w porównaniu z kładką. Długość segmentu wynosi 2,35 m, a wymiary gabarytowe przekroju poprzecznego są równe 0,60 m × 0,26 m (szerokość × wysokość). Komponenty laminatów, klej oraz technologia wytwarzania segmentu walidacyjnego są takie same jak w przypadku kładki kompozytowej. Opracowano metodykę modelowania numerycznego i symulacji z wykorzystaniem metody elementów skończonych belek kompozytowych w formie dwóch sklejonych ze sobą powłok kompozytowych. Metodyka została opracowana w odniesieniu do segmentu walidacyjnego poddanego trójpunktowemu zginaniu ze ścinaniem. Walidację eksperymentalną modelowania i symulacji przeprowadzono w podstawowym przypadku laminatów nowych w temperaturze 20°C. Do numerycznego modelowania i symulacji zastosowano kod elementów skończonych MSC.Marc 2010.

16

Numerical model of a cross-flow heat exchanger with non-uniform flow of media

Hanuszkiewicz-Drapala M., Bury T., Widziewicz K.

Journal of Power Technologies

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2013

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Vol. 93, nr 5

295--302

EN

This paper presents thermal-hydraulic analyses of finned cross flow heat exchangers working in media flow maldistribution conditions. The authors postulate a possibility of performing such analyses through the use of CFD models of recurrent segments of the heat exchangers. Media inflow to each recurrent segment may be individually defined and thus the flow maldistribution in the whole heat exchanger could be considered. The methodology of creating these models, running calculations and results of very initial experimental validation is presented in the paper.

17

The comparison of density-elastic modulus equations for the distal ulna at multiple forearm positions : a finite element study

Neuert M. A. C., Austman R. L., Dunning C. E.

Acta of Bioengineering and Biomechanics

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2013

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Vol. 15, no. 3

37--43

EN

The accuracy of an empirically derived density-modulus equation for bone depends upon the loading conditions and anatomic site of bone specimens used for experimentation. A recent study used FE modeling to compare the ability of three density-modulus relationships to predict strain during bending in neutral forearm rotation in the distal ulna; however, due to the inhomogeneous nature of these FE models, the performance of each equation is not necessarily consistent throughout forearm rotation. This issue is addressed in the present study, which compares the performance of these equations in pronation and supination. Strain gauge data were collected at six discreet locations of six ulna specimens loaded in bending at 40° of pronation and supination. Three FE models of each specimen were made, one for each density-modulus relation, and the strain output compared to the experimental data. The equation previously shown to be most accurate in predicting ulnar strain in neutral forearm rotation was also most accurate in pronation and supination. These results identify this one equation as the most appropriate for future FE analysis of the ulna (including adaptive remodeling, and further show that isotropic and inhomogeneous FE bone models may provide consistent results in different planes of bending.

18

Identification of layers distribution in the composite coupon using finite element method and three point bending test

Mazurkiewicz Ł., Małachowski J., Damaziak K., Baranowski P., Gotowicki P.

Acta Mechanica et Automatica

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2013

|

Vol. 7, no. 3

160--165

EN

The main objective of the study is to develop experimentally validated FE model and perform numerical analysis of layered composites made by hand lay-up techniques during tension and bending test. The research object is glass - polyester laminate made of four unidirectional layers. In order to validate the numerical models experimental test were performed. Due to the very different stiffness modulus in tension and bending loading the material properties obtained from standard test are not suitable to apply in numerical model. Significantly different behaviour compared to experimental test was obtained for tree point bending where the numerical model becomes too stiff. Simple coupons, relatively easy to manufacture presented in the paper have very low quality. The differences in actual and theoretical bending stiffness (obtained from tension stiffness) exceed 70%. In order to represent the actual structure the layers of the composite were divided by resin layers and also additional resin layer at the top and bottom of the model were defined. Single stage optimization process was used to adjust the material layout. After layer set-up modification very significant improvement can be seen for flexural behaviour.

19

Validation of services supporting healthcare standards conformance

Górski J., Jarzębowicz A., Miler J.

Metrology and Measurement Systems

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2012

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Vol. 19, nr 2

269-282

EN

The paper presents the results of experimental validation of a set of innovative software services supporting processes of achieving, assessing and maintaining conformance with standards and regulations. The study involved several hospitals implementing the Accreditation Standard promoted by the Polish Ministry of Health. First we introduce NOR-STA services that implement the TRUST-IT methodology of argument management. Then we describe and justify a set of metrics aiming at assessment of the effectiveness and efficiency of the services. Next we present values of the metrics that were built from the data collected. The paper concludes with giving the interpretation and discussing the results of the measurements with respect to the objectives of the validation experiment.

20

Numerical modeling of unsteady state operation of tube and plate fin heat exchangers

Taler D., Korzeń A.

Journal of Energy Science

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2012

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Vol. 1, nr 2

103--117

EN

Cross-flow tubular heat exchangers are applied as condensers and evaporators in air conditioners and heat pumps or as air heaters in heating systems. They are also applied as water coolers in so called 'dry' water cooling systems of power plants, as well as car radiators. There are analytical and numerical mathematical models of heat exchangers of that type to determine the steady state temperature distribution of fluids and the rate of heat transferred between fluids. In view of the wide range of applications in practice, these heat exchangers were experimentally examined in steady-state conditions, mostly to determine the overall heat transfer coefficient or the correlation for the heat transfer coefficients on the air side and on the internal surface of the tubes. There exist many references on the transient response of heat exchangers. Most of them, however, focus on the non-steady-state heat transfer processes in parallel and counter flow heat exchangers. In this paper, the new equation set describing transient heat transfer process in tube and fin cross-flow tube exchanger will be given and subsequently solved using the finite volume method.