Wyniki wyszukiwania - BazTech

1

Neuro-genetic optimization of ribbed heat exchanger using entropy augmentation generation number

Konchada Pavan K., Sukhvinder Bhatti, Relangi Siddhardha, Chekuri Rambhadriraju

Archives of Thermodynamics

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2020

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Vol. 41, no 2

169--184

EN

Numerical predictions of heat transfer under laminar conditions in a square duct with ribs are presented in this paper. Ribs are provided on top and bottom walls in a square duct in a staggered manner. The flow rates have been varied between Reynolds number 200 and 600. Various configurations of ribs by varying length, width and depth have been investigated for their effect on heat transfer, friction factor and entropy augmentation generation number. Further artificial neural network integrated with genetic algorithm was used to minimize the entropy augmentation generation number (performance factor) by selecting the optimum rib dimensions in a selected range. Genetic algorithm is compared with microgenetic algorithm to examine the reduction in computational time for outlay of solution accuracy.

2

Rib kinematics analysis in oblique and lateral impact tests

Jastrzębski Dominik, Perz Rafał

Acta of Bioengineering and Biomechanics

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2020

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Vol. 22, no. 1

135--141

EN

Understanding thorax kinematics and rib breaking mechanisms in conditions of oblique and lateral impact is crucial in safety systems development. To increase knowledge level on this subject, simulation and experimental tests are necessary. The purpose of this study was to obtain single rib kinematics in the case of oblique and lateral impact conditions using numerical simulation approach. Methods: Two impact tests using human body model of a 50th percentile man (THUMS v4.0.1 AM50) were performed in LS-Dyna R7.1.1. Impactor was a rigid cylinder with a diameter of 152 mm, and velocity equal to 6.7 m/s. Impact angle measured to sagittal plane was 30 and 90°, respectively in oblique and lateral impact case. Results: Kinematics of ribs from 3rd to 6th were analyzed. Results shown significant similarities between oblique impact and kinematics of ribs tested in frontal impact conditions in the literature, with maximal costochondral joint displacement relatively to costovertebral joint varying from 65.4 mm (3rd rib) to 82.0 mm (5th rib). Deformation of rib in lateral impact conditions was different than during oblique impact test, with distinctive “flattening” approximately in the middle of the rib. Maximal relative displacement varies from 16.4 mm (6th rib) to 26.6 mm (5th rib) and its location depends on the analyzed rib. Conclusions: Oblique impact scenario may be simulated for the single rib on an experimental way using set-up of the frontal impact. Experimental simulation of the lateral impact for the single rib should not use the same set-up, as the kinematics analysis showed significant differences between simulated cases.

3

Mechanical and histomorphometrical evaluation of false and floating ribs of young adults with idiopathic scoliosis

Głowacki Jakub, Tomanik Magdalena, Pezowicz Celina, Krauss Hanna

Acta of Bioengineering and Biomechanics

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2020

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Vol. 22, no. 2

3--10

EN

The aim of this paper was to assess the histomorphometrical and mechanical properties of ribs in patients with idiopathic scoliosis who underwent corrective surgery of scoliosis combined with thoracoplasty. Methods: The analyzed material encompasses 20 females between the ages of 12 and 18, whose pre-operative Cobb angle was 56.85 degrees, on average. The participants were divided into two age groups, up to the age of 15 and above 15 years old, taking into account the anatomical location of the assessed rib fragments with a division into floating and false ribs. The analysis of mechanical parameters was carried out by means of the quasi-static 3-point bending test, and the histomorphometric evaluation of the examined rib fragments was carried out using high-resolution computed tomography. Results: The existence of explicit relationships between selected radiological parameters describing scoliosis and mechanical and histomorphometric parameters of the ribs has not been confirmed. Statistically significant correlations between age and rib stiffness as well as between Young’s modulus and stiffness depending on the anatomical location of the examined rib fragment were confirmed. Conclusions: Mechanical and histomorphometric properties of bone tissue in patients with scoliosis are not explicitly associated with the radiological parameters characterizing scoliosis.

4

Wpływ grubości żeber na wartości temperatury na powierzchni płyty w ogrzewaniu podłogowym

Wiśnik K., Sabiniak H. G.

Ciepłownictwo, Ogrzewnictwo, Wentylacja

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2018

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T. 49, nr 3

103--106

PL

W artykule wykorzystano koncepcję żebra, polegającą na rozwinięciu powierzchni wymiany ciepła rur grzewczych zatopionych w warstwie jastrychu, co prowadziło do zwiększenia ilości oddawanego ciepła z powierzchni płyty grzewczej, przy jednoczesnym obniżeniu temperatury czynnika zasilającego. W artykule przedstawiono wpływ zmiany grubości żeber prostokątnych zatopionych w warstwie jastrychu na rozkład temperatury na powierzchni płyty grzewczej. Badania empiryczne w warunkach ustalonej wymiany ciepła wykonane zostały z wykorzystaniem programu Ansys.

EN

In the research a concept of rib is used, in which the surface of heat exchange in the heating pipes has been developed, which leads to increase of the amount of heat transmitted from the surface of the heating plate with a subsequent lowering of the supply factor temperature. The article presents the effect of changing the thickness of rectangular ribs on the distribution of temperatures on the surface of heating plate. Numerical analyses have been carried out for the predetermined states on the basis of the finite element method in the Ansys program.

5

Rzeczywisty rozkład temperatury na powierzchni płyt grzewczych

Sabiniak H. G., Wiśnik K.

Instal

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2015

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nr 2

44--46

PL

W artykule przedstawiono możliwości rozwinięcia powierzchni wymiany ciepła rur zasilających w ogrzewaniu podłogowym. Zbadano wpływ kształtu i odległości między żebrami na rozkład temperatury na powierzchni płyty grzewczej w zależności od zmiennej wartości temperatury czynnika zasilającego. Badania doświadczalne przeprowadzone zostały dla stanów ustalonych.

EN

The article presents possibilities of developing the heat transfer area of supply pipes in underfloor heating. It examines the influence of ribs shape and distance between them on the distribution of temperature on the surface of heating plate depending on the variable value of temperature of the heating factor. Experimental analyses have been carried out for the established states.

6

Dome over the Gdynia seaport building

Godycki-Ćwirko T., Nagrodzka-Godycka K., Piotrkowski P.

Archives of Civil Engineering

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2014

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Vol. 60, nr 2

223--239

EN

The paper presents the description of structure and the selected problems of the technical condition, as well as the strength analysis of the thin-walled reinforced concrete shell which has been making a covering of the main hall of the Gdynia Seaport Building through the last 80 years. The rectangle projection of four single curvature shells of the dome was shaped out of mutual perpendicular intersection of two cylindrical shells. The analysis of the state of stress and deformations was carried out using the special model worked out in MES considering the combination of loads, the thermal ones included. For the long lasting loads (the deadweight of the dome), the computed results of static quantities were confronted with analytical results obtained according to F. Dischinger’s method. This method had been applied by the DYWIDAG Company in Berlin and its branch in Katowice (Poland) who designed the Gdynia Dome. The computational analysis and the assessment of the technical state, along with laboratory pH tests of concrete, made it possible to carry out the overall evaluation of durability and safety of operation of the Gdynia Seaport Dome through the next decades.

7

The mechanical properties of human ribs in young adult

Pezowicz C., Głowacki M.

Acta of Bioengineering and Biomechanics

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2012

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Vol. 14, no. 2

53-60

EN

A good understanding of thoracic biomechanics is important for complete examination and control of chest behaviour under conditions of physiological and pathological work, and under the impact of external forces leading to traumatic loading of the chest. The purpose of the study was to analyse the mechanical properties of human ribs obtained from individuals under the age of 25 with scoliosis deformation and to correlate them with geometric properties of ribs. Thirty three fragments of ribs (9th to 12th) were tested in three-point bending. Rib fragments were collected intraoperatively from female patients treated for scoliosis in the thoracic, thoracolumbar, and lumbar spine. The results were used to determine the maximum failure force, stiffness, and Young's modulus. A significant relationship was found between the age and elastic modulus of the ribs. The analysis was carried out for two age groups, i.e., between the ages of 10 and 15 and between the ages of 16 and 22, and statistically significant differences were obtained for Young's modulus ( p = 0.0001) amounting to, respectively, 2.79 +- 1.34 GPa for the first group and 7.44 š+-2.85 GPa for the second group. The results show a significant impact of age on the mechanical properties of ribs.

8

Racjonalny układ żeber i otworów w środniku blachownic stalowych

Chybiński M., Garstecki A.

Zeszyty Naukowe Politechniki Rzeszowskiej. Budownictwo i Inżynieria Środowiska

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2011

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z. 58, nr 3/II

225-232

PL

Praca przedstawia wyniki analizy nośności blachownic stalowych dla różnych układów żeber i otworów wyciętych w środniku. Bada się stateczność globalną i lokalną. Analizy prowadzi się metodą elementów skończonych z zastosowaniem elementów typu powłokowego. Przeprowadzono zarówno analizy liniowe jak i nieliniowe z uwzględnieniem wstępnych imperfekcji geometrycznych. Wyniki analiz potwierdziły, że zarówno konfiguracja użebrowania jak i rozmieszczenie oraz kształt otworów w środniku mają bardzo duży wpływ na nośność blachownic, co uzasadnia celowość podjętych badań.

EN

The stability of girders with various orthogonal and diagonal configurations of ribs is studied using FEM with shell elements. Linear stability analysis was carried out for a numerous set of rib configurations, with variable web thickness and different shapes of openings. Nonlinear stability analyses accounting for initial geometric imperfection were performed for a beam with orthogonal ribs and its counterpart with diagonal ones. Linear and nonlinear analyses demonstrated that a rationally designed configuration of ribs and openings can strongly improve the stability response of girders. Diagonal configuration proved to be more favorable.

9

Boiling heat transfer on ribs with temperature dependent conductivity

Orzechowski T., Orman Ł.

Turbulence : international journal

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2004

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Vol. 10

91-98

EN

In the paper theoretical analysis of the performance of the rib with porous micro-structure has been conducted. The microstructure has been modelled by microrib of the rectangular cross-section. Thermal conductivity of the material of the rib has been assumed to be linearly dependent on temperature. For such a configuration an equation of the rib during boiling with heat transfer coefficient exponentially dependent on the wall superheat has been presented and calculated. Both the efficiency and the effectiveness have also been determined.