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1

Structural Analysis and Pegmatite Differentiation in the Ancient Claim, Giraúl IV, Namibe Pegmatite District, Angola

Leal Gomes Carlos

Inżynieria Mineralna

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2024

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Vol. 1, no. 1

33--42

EN

Since the early 60´s, in the past XX century, the Giraúl pegmatites have been known for their resources of beryl, mica and feldspars, which were exploited in a regular basis from Giraúl claims I to IV till 1974, during the Portuguese administration of Angolan territory. A broader exploration of this pegmatite field was performed by the ancient Lobito Mining Company (LMC) engaged in detailed geological mapping of the granitic pegmatites and the structural constraints of their location. A structural map of the region was than elaborated, combining the interpretation of aerial photographs with field work performed by the LMC geologists. Recently, a growing economic interest is attributed to these claims, in the region of Bulamucolocai, Pitau and Muvero desert-dry rivers (locally known as “Mulolas”), considering the Li, Cs, and Ta (LCT) metallic specialization of some pegmatite bodies and the occurrence of beryl and tourmaline gemstones, mainly, morganite (Cs-beryl), aquamarine and also elbaite-liddicoatite. Giant crystals of spodumene, up to 6 m in length, define individualized quartz + spodumene units inside some of the more typical LCT pegmatite bodies. Pollucite was identified in the main pegmatites of Giraúl IV claim and not in the adjacent igneous leucocratic breccias. These, in turn, correspond to a complex pegmatite assemblage, very peculiar in what concerns its selective metasomatic effect over some surrounding rocks, with the formation of rims of holmquistite amphibole in contact with gabbro and norite and schorl-dravite tourmaline in contact with gneissic to metapelitic hosts. The breccia-like granitic rock combines clasts of spodumene an K-feldspar with a matrix mainly composed of some quartz, albite and mica including tourmaline, garnet and F-apatite, as accessory minerals. In the same area, huge potassic pegmatites hold giant crystals of microcline and orthoclase and very little quartz, being unusual due to its high content of triplite – zwieselite and triphylite – lithiophilite primary phosphates. The overall composition of these pegmatites is more likely syenitic (low quartz content) than truly granitic. A high-resolution structural analysis of the LCT ensemble (pegmatite plus related lithotypes) is now proposed enhancing the unusual relations between granite breccia plugs, sill-like more typical pegmatites, irregular shaped isodiametric bodies and products of metasomatism. This approach will lead to the understanding of the true dimension, anatomy and inner fraccionation of the different LCT facies and rare-metal deposits with obvious consequences regarding mineral detection and resource – reserve estimation, through the proposal of a more suitable conceptual model to rule its exploration.

2

Space debris capture - about new methods of tethered space net opening by tubular booms

Pałgan Tomasz, Dacko Adam, Rataj Mirosław, Polak Szymon

Artificial Satellites : Journal of Planetary Geodesy

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2024

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Vol. 59, No. 1

1--10

EN

Nowadays, space debris is one of the main subjects of discussion regarding satellites in Earth’s orbit. Right now, there are about 26,000 orbiting satellites and only few of these satellites are operational. Recently, the Polish space sector has been strongly growing and delivering instruments working in space. The first part of this paper describes the several space instruments designed in the Space Research Centre Polish Academy of Science (SRC PAS). Instruments such as SWI, RPPWI, LPPWI, Ebox or Pre-boxes have been created for a mission to Jupiter named “JUICE”. After fulfilling their scientific mission, these instruments can increase the amount of debris in space. This is one of the reasons for taking up the topic of space debris reduction and the use of technical solutions used in this mission for the proposed solution presented later. The second part of this paper describes the new methods related to space debris. The activities can be related to the space debris removal programmes. The paper describes two methods developed by Polish scientists used for removal of space debris. One of them is the new capture method and mechanism designed for it. The special mechanism is based on tubular boom application for opening the net, to capture the space debris. The main parts of the mechanism are mechanisms which have been used in the JUICE space mission. The paper describes the main idea for these new methods, and for the design part prepared the strength confirmation by structural analysis. The main function of the mechanism has been verified by simulations and tests performed in laboratories.

3

Wybrane przykłady modelowania i analizy strukturalnej problemów decyzyjnych w budownictwie

Śladowski Grzegorz

Przegląd Budowlany

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2023

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R. 94, nr 1-2

98--102

PL

W artykule zwrócono uwagę na ważny aspekt, jakim jest modelowanie i analiza strukturalna problemów w procesie decyzyjnym. Zaprezentowane podejście systemowe na tle klasycznych wielokryterialnych metod wspomagania decyzji pozwala uwzględnić różne współzależne zewnętrzne i wewnętrzne relacje między kryteriami i wariantami decyzyjnymi, co jest istotne z perspektywy modelowanej rzeczywistości. Przedstawiono podstawowe metody modelowania i analizy struklturalnej, a całość rozważań została poparta wybranymi przykładami problemów decyzyjnych w budownictwie.

EN

This paper notes the important aspect of the modeling and structural analysis of problems in decision making. Against classical multi-criteria decision-making support methods, the presented approach considers different co-dependent external and internal relations between criteria and decision alternatives, which is significant from the standpoint of the reality we aim to model. Essential structural modeling and analysis methods were presented, and the entire discussion was backed by samples of decision problems from the construction sector.

4

The structure of the Silesian Beskid Block in the Vistula River source area in the Western Outer Carpathians (southern Poland)

Sikora Rafał

Annales Societatis Geologorum Poloniae

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2023

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Vol. 93, No. 2

137--163

EN

This paper presents new results of a detailed structural analysis of the bedrock of the Vistula source area within the Silesian Beskids (Outer Western Carpathians, S Poland). The bedrock of the study area is composed of the Upper Cretaceous flysch series of the Upper Godula Beds and Lower Istebna Beds. The study area is located on the southern limb of the Szczyrk Anticline within the Silesian Beskid Block. The research is based on cartographic field work and remote sensing analysis of a digital elevation model from LiDAR data. The structural analyses were supported by the extraction of the topolineaments and their spatial analysis. The results presented show that the monoclinal bedrock structure of the study area can be characterized by a systematic joint pattern, which determined the existence of faults and fault zones. Moreover, detailed analyses show differences in fracturing of the sedimentary strata and the existence of hidden fracture zones, not visible in the previous map view. Most of the faults are related to an orthogonal joint system, whereas the transverse and longitudinal faults are connected with fold and thrust structures that are exposed in outcrops and reflected in the topography. Kinematic analysis shows that the NW–SE-trending transverse faults underwent dextral movements, while the ENE–WSW-trending longitudinal faults recorded sinistral displacements. Furthermore, older strike-slip and oblique-slip displacements along faults were overprinted by normal dip-slip faulting. The new tectonic and relief data show no existence of the Gościejów Syncline in the northern part of the study area, which was depicted on previous maps. In conclusion, normal faulting and damage of the bedrock along fracture zones are interpreted as being related to the posttectonic, gravitational collapse of the rock massif. Its detailed recognition is very important for the further study of relationships between bedrock structure and mass movement characteristics, such as the geometry and kinematics of landslides.

5

Physical and reliability aspects of high-pressure ammonia water pipeline failures

Michnej Maciej, Młynarski Stanisław, Pilch Robert, Sikora Wojciech, Smolnik Maksymilian, Drożyner Przemysław

Eksploatacja i Niezawodność

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2022

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Vol. 24, no. 4

728--737

EN

The paper concerns the problem of the occurrence of failures of the high-pressure ammonia water pipeline of the coke oven battery complex, which is affected by chemical and thermal factors as well as the operating pressure occurring during its use. Pipeline failures manifested themselves as leaks (leakage of the medium) due to cracks in the area of the pipeline thermal elongation compensators. The conducted tests included, among others: visual inspection, penetration tests, macroscopic and microscopic tests as well as chemical analysis of the material. The study includes microscopic photographs of the material structure and cracks. The results of the pipeline strength and reliability analysis were also presented. On the basis of the conducted research and analyses conclusions were formulated. The assumed cause of the damage was the incorrectly made welded joints. Formulated recommendations and proposals for actions aimed at avoiding further failures of this and similar pipelines were related to the inspection time and preventive renewal.

6

Optimization of gear teeth in the wind turbine drive train with gear contact’s uncertainty using the reliability-based design optimization

Lee Changwoo, Park Yonghui

Archive of Mechanical Engineering

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2022

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LXIX, nr 4

713--728

EN

Although gear teeth give lots of advantages, there is a high possibility of failure in gear teeth in each gear stage in the drive train system. In this research, the authors developed proper gear teeth using the basic theorem of gear failure and reliability-based design optimization. A design variable characterized by a probability distribution was applied to the static stress analysis model and the dynamics analysis model to determine an objective function and constraint equations and to solve the reliability-based design optimization. For the optimization, the authors simulated the torsional drive train system which includes rotational coordinates. First, the authors established a static stress analysis model which gives information about endurance limit and bending strength. By expressing gear mesh stiffness in terms of the Fourier series, the equations of motion including the gear mesh models and kinematical relations in the drive train system were acquired in the form of the Lagrange equations and constraint equations. For the numerical analysis, the Newmark Beta method was used to get dynamic responses including gear mesh contact forces. From the results such as the gear mesh contact force, the authors calculated the probability of failure, arranged each probability and gear teeth, and proposed a reasonable and economic design of gear teeth.

7

Structure and metamorphism of the Dardania zone in the eastern part of Gjilan region (Kosovo)

Kutllovci Festim

Mining Science

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2021

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Vol. 28

93--102

EN

The Dardanian zone represents the western part of the Rhodope crystalline basement. This zone was structured and metamorphosed during the Hercynian and post Hercynian tectonic stages. The important aspects have been identified in the structure and metamorphism from this part of western Rhodopes. The geological setting of study region has clarified the most important aspects regarding: structural geology, deformation, tectonics, and metamorphism. The studied region represents an important node in the geology of Kosovo and beyond. In this region there is the border of the Vardar unit and the Serbo-North Macedonian tectonic unit (Dardania Massif). The Serbo-North Macedonian Massif (eastern part of Kosovo) structurally represents the upper part of Dacia and the innermost whole, compared to the Carpathian-Balkanids described above. The Crystalline belt of metamorphic rocks belongs to high-grade metamorphism. The rocks of the Upper Complex represent a volcano-sedimentary sequence that is metamorphosed only under greenschist facies conditions. The Lower Complex consisting of gneiss, micaschists and to a lesser extent amphibolites, quartzites, marbles and migmatites. The main event of the Hercynian tectonic period that structured the rocks forming in the Dardania zone is associated with the regional deformation D2. Its intensity is depending on the type of rocks, but it is noted an increase of the intensity from west to east. The associated schistosity S2(penetrating schistosity)is an axial plane schistosity of the isoclinals folds S0, S1. The schistosity S2 is homogenous, with an average strike direction of 345° and dip direction of 45°. The intersection lineation (L2) and the fold axis (B2) are very homogenous with the dip azimuth toward N (350°) and dip angle of 10°. The deformation D3 is associated with the crenulations of schistosity S3. The schistosity S3 represents the axial plan of the kink fold and crenulation. The schistosity S3 is very heterogeneous and it is difficult to arrive at conclusions regarding the average direction of this planar structure also to judge the kinematic aspects of the movement. Likewise, the axis of the crenulations B3 and L3 lineation represent relative heterogeneous linear structures. The deformation D4 is associated with the fracture schistosity S4. The schistosity S4 often show the axial plan of the open parallel folds. The schistosity S4 is homogenous with the range East–West with symmetric drop (in the N and S), by proving that we are dealing with a phase of deformation with an extensional tectonic regime (with the direction N–S).

8

Reduced equations of slope-deflection method in structural analysis

Husain Muhammed Abbas, Hasan Zahraa Hameed

International Journal of Applied Mechanics and Engineering

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2021

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Vol. 26, no. 4

51--62

EN

This paper presents an update of the slope-deflection method, which is used in the analysis of statically indeterminate structures. In this study, new reduced equations are presented based on including both the effects of the member rotations and the fixed end moments in one term, rather than two terms, in order to simplify the application of the slope-deflection method. The reduced equations are developed, then three numerical examples with comprehensive cases of beams are solved by applying both the original and the proposed reduced equations. The analysis outputs indicated that the reduced equations are applicable for all cases that can be analyzed by the slope-deflection method, and give identical results compared with the original equations. It is found that the reduced equations require less computations when the structure has no support settlement, compared with the original equations, whereas the computations are approximately similar when the structure has a support settlement.

9

Structural Analysis and Optimization of Electric Bike Front Drive with Bottom Bracket Electric Motor

Mesic Elmedin, Masic Adnan, Muratovic Enis, Delic Muamer, Hasanbegovic Salem

Advances in Science and Technology. Research Journal

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2021

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Vol. 15, no 1

273--282

EN

The main objective of this research was to propose a light and practical design solution for electric bike front drive with bottom bracket electric motor. The initial design needs to be redesigned so it can enable simultaneous use of the electric drive and pedal drive, with integration of the front gear shifter. After gathering the basic information linked to the problem and inspecting the initial design solution, the assets and flaws have been identified. The CAD models of the considered possible solutions were developed into FEM models which were used for struc- tural analysis in CAD/CAE software system CATIA. On the basis of the FEM analysis and additional criteria, the optimal solution was chosen, and structural optimization, based on FEM model, was performed. A prototype was manufactured and a mounting process in a place of the initial design was performed. Afterwards, electric bike with mounted prototype was tested under real conditions.

10

Building of calculation model and strength analysis by using finite element method on example of mold to foaming of cooling furniture

Ignasiak Łukasz, Woźniak Paweł, Bieńczak Agata

Journal of Research and Applications in Agricultural Engineering

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2020

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Vol. 65, nr 1

4--8

EN

The article presents the way of creating calculation model of mold to foaming of cooling furniture for needs of conducting strength analysis by using Finite Element Method. The method of creating model is described in detail taking into account of modeling techniques available in NX system, the division of model into finite elements (discretization) by using threedimensional, two-dimensional, one-dimensional elements was visualized. Finally, the results of numerical simulations in the form of stresses distribution in areas of considerable straining of structure was presented.

PL

W artykule przedstawiono sposób tworzenia modelu obliczeniowego formy do spieniania mebli chłodniczych dla potrzeb przeprowadzenia analiz wytrzymałościowych przy wykorzystaniu Metody Elementów Skończonych. Szczegółowo opisano metodę kreowania modelu z uwzględnieniem technik modelowania dostępnych w systemie NX, zobrazowano podział modelu na elementy skończone (dyskretyzację) przy wykorzystaniu elementów trójwymiarowych, dwuwymiarowych oraz jednowymiarowych. Przedstawiono wyniki z przeprowadzonych symulacji numerycznych w postaci rozkładu naprężeń w obszarach o znacznym wytężeniu.

11

Study of AlSi9Cu3 Alloy Crystallization Process with Increased Iron Content at Different Number of Remelts

Matejka M., Bolibruchova D., Kasińska J., Kuriš M.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 1

79--83

EN

Monitoring the solidification process is of great importance for understanding the quality of the melt, for controlling it, and for predicting the true properties of the alloy. Solidification is accompanied by the development of heat, the magnitude of which depends on the different phases occurring during solidification. Thermal analysis is now an important part of and tool for quality control, especially when using secondary aluminium alloys in the automotive industry. The effect of remelting on the change of crystallization of individual structural components of experimental AlSi9Cu3 alloy was determined by evaluation of cooling curves and their first derivatives. Structural analysis was evaluated using a scanning electron microscope. The effect of remelting was manifested especially in nucleation of phases rich in iron and copper. An increasing number of remelts had a negative effect after the fourth remelting, when harmful iron phases appeared in the structure in much larger dimensions.

12

New optimization algorithms and their application for 2D truss structures

Grzywiński Maksym, Dede Tayfun

Zeszyty Naukowe Politechniki Częstochowskiej. Budownictwo

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2019

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Z. 25 (175)

50-54

EN

In this study, two new algorithms named Rao-1 and Rao-2 are presented for the optimization of 2D truss structures. The main purpose of the optimization algorithms, used in this study, is to minimize the total weight of the truss structure. When carrying out this purpose, the allowable displacement and stress are taken into account as the constraints. The design variables are the cross-sectional areas of the steel truss bar elements. To calculate the structural response, the finite element analysis is coded in MATLAB. The optimal results obtained in this study are compared with those given in the literature in order to demonstrate the efficiency of the proposed algorithms.

PL

Przedstawiono nowe algorytmy o nazwach Rao-1 i Rao-2 do optymalizacji płaskiej kratownicy. Głównym celem problemu optymalizacyjnego zastosowanego w tym badaniu jest minimalizacja całkowitej masy konstrukcji kratownicy. Przy realizacji tego celu dopuszczalne przemieszczenia i naprężenia są uwzględniane jako ograniczenia. Zmienne projektowe to pola przekroju poprzecznego stalowych elementów kratownicy. Aby obliczyć optymalną konstrukcję, zastosowano metodę elementów skończonych zakodowaną w MATLAB-ie. Optymalne wyniki uzyskane w tym badaniu są porównywane z podanymi w literaturze w celu wykazania wydajności proponowanego algorytmu.

13

Large-scale deformations in Neogene deposits near Dobrzyń on the Vistula (central Poland) – thrusting from N/NE or valley-side glaciotectonics in the Płock Basin?

Roman Małgorzata, Żuk Rafał

Studia Quaternaria

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2019

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Vol. 36, Nr 2

147--159

EN

The article is focused on the most recent investigations of glaciotectonic structures in high escarpment exposures of the Vistula valley from Dobrzyń to Kuzki in the western part of the Płock Basin. Deformations involve Neogene and occasionally the Lower Pleistocene deposits and they are not expressed as landforms. Structural investigations and analysis of archival geological data provided new information on the origin of large-scale shear structures. Results obtained are clearly contrary to the concept of Brykczyński (1982) regarding valley-side glaciotectonics in the Płock Basin. An emergence of the extensive zone of serial thrust structures of significant amplitude (up to 100–150 m) was found to have not been controlled by a palaeovalley. A driving mechanism is interpreted as a gravity spreading in front of ice sheets advancing from north-northeast during the South Polish Complex (Dorst-Elsterian).

14

Mixed structure Zn(S,O) nanoparticles: synthesis and characterization

Dhupar Anu, Kumar Suresh, Sharma Vandana, Sharma J. K.

Materials Science Poland

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2019

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Vol. 37, No. 2

230--237

EN

In the present work, mixed structure Zn(S,O) nanoparticles have been synthesized using solution based chemical coprecipitation technique. Two different zinc sources (Zn(CH3COO) 2·2H2O and ZnSO4·7H2O) and one sulfur source (CSNH2NH2) have been used as primary chemical precursors for the synthesis of the nanoparticles in the presence and absence of a capping agent (EDTA). The structural, morphological, compositional and optical properties of the nanoparticles have been analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transmission infra-red (FT-IR) and UV-Visible (UV-Vis) spectroscopy. XRD revealed the formation of mixed phases of c-ZnS, h-ZnS and h-ZnO in the synthesized nanoparticles. The surface morphology was analyzed from SEM micrographs which showed noticeable changes due to the effect of EDTA. EDX analysis confirmed the presence of zinc, sulfur and oxygen in Zn(S,O) nanoparticles. FT-IR spectra identified the presence of characteristic absorption peaks of ZnS and ZnO along with other functional group elements. The optical band gap values were found to vary from 4.16 eV to 4.40 eV for Zn(S,O) nanoparticles which are higher in comparison to the band gap values of bulk ZnS and ZnO. These higher band gap values may be attributed to the mixed structure of Zn(S,O) nanoparticles.

15

The influence of high-strength bolts stiffening on flange connection behaviour

Major Izabela, Kuliński Krzysztof, Major Maciej

Engineering Transactions

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2019

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Vol. 67, iss. 2

199--211

EN

Flange connections can commonly be seen in advertising board structures, which are subjected to wind loading. Depending on the structure’s geometry, additional torsion forces should be taken into account. In this paper the static behaviour of a flange connection with highstrength bolts under torsion load has been discussed. The numerical analysis concerns two cases: a flange connection subjected only to a high-strength bolts prestressing load and a flange connection subjected to both – bolts prestressing force and torsion moment. The stated boundary problem has been solved with the use of SolidWorks software. The obtained numerical results show good agreement with the analytical method.

16

Development of Parametric CAD Model and Structural Analysis of the Car Jack

Pervan Nedim, Muminović Adis J., Muminović Adil, Delić Muamer

Advances in Science and Technology. Research Journal

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2019

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Vol. 13, no 3

24--30

EN

The purpose of a car jack is lifting the car and maintaining it at a certain height during different repairs. This paper focuses on the design of car jack, which belongs to the basic equipment of cars. Cars jacks are used mainly for changing tires and small repairs of a car. The aim of this paper was to create a parametric CAD model of a car jack and carry out numerical structural analysis of the car jack using the created parametric CAD model. The development of the parametric CAD model and structural analysis was performed using the CATIA V5 system. This paper describes the modern way of creating more complex mechanisms, which support quick modification of its parameters, and thus the entire design. The whole model of the car jack was parametrized. The stresses obtained by finite element method (FEM) analysis were confirmed with the analytical calculation in characteristic parts of the design, with some exceptions. At the end of the paper, an analysis of the obtained results was performed, on the basis of which specified conclusions were made.

17

The intramontane Orava Basin - evidence of large-scale Miocene to Quaternary sinistral wrenching in the Alpine-Carpathian-Pannonian area

Ludwiniak Mirosław, Śmigielski Michał, Kowalczyk Sebastian, Łoziński Maciej, Czarniecka Urszula, Lewińska Lena

Acta Geologica Polonica

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2019

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Vol. 69, no. 3

339--386

EN

The Carpathian Orava Basin is a tectonic structure filled with Neogene and Quaternary deposits superimposed on the collision zone between the ALCAPA and European plates. Tectonic features of the south-eastern margin of the Orava Basin and the adjoining part of the fore-arc Central Carpathian Palaeogene Basin were studied. Field observations of mesoscopic structures, analyses of digital elevation models and geological maps, supplemented with electrical resistivity tomography surveys were performed. Particular attention was paid to joint network analysis. The NE-SW-trending Krowiarki and Hruštinka-Biela Orava sinistral fault zones were recognized as key tectonic features that influenced the Orava Basin development. They constitute the north-eastern part of a larger Mur-Mürz-Žilina fault system that separates the Western Carpathians from the Eastern Alps. The interaction of these sinistral fault zones with the older tectonic structures of the collision zone caused the initiation and further development of the Orava Basin as a strike-slip-related basin. The Krowiarki Fault Zone subdivides areas with a different deformation pattern within the sediments of the Central Carpathian Palaeogene Basin and was active at least from the time of cessation of its sedimentation in the early Miocene. Comparison of structural data with the recent tectonic stress field, earthquake focal mechanisms and GPS measurements allows us to conclude that the Krowiarki Fault Zone shows a stable general pattern of tectonic activity for more than the last 20 myr and is presently still active.

18

Shaping curved steel rod structures

Dźwierzyńska J.

Technical Transactions

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2018

|

Vol. 115, iss. 8

87--98

EN

The paper addresses the problem of the efficient shaping of curved steel rod structures conducted based on the Enneper surface. The proposed parametric design process consists in linking the geometric shaping of grid models with their structural analysis and optimization, which is realized through the application of design tools working in the Rhinoceros 3D software. The mechanical performance of lattices covered with glass panels is evaluated and the structures are pre-dimensioned. The presented aesthetic grid shells with good structural characteristics may constitute original coverings. However, the analysis, which targets an early stage of the design, aims at providing design guidelines to facilitate communication between architects and civil engineers.

PL

W artykule podejmuje się problem efektywnego kształtowania krzywoliniowych, stalowych konstrukcji prętowych utworzonych na bazie powierzchni Ennepera. Zaproponowany parametryczny proces kształtowania polega na powiązaniu geometrycznego kształtowania siatkowych modeli z ich analizą strukturalną i optymalizacją, realizowanymi za pomocą narzędzi projektowych pracujących w środowisku Rhinoceros 3D. Oceniono mechaniczne właściwości kratownic pokrytych taflami szklanymi, a struktury wstępnie zwymiarowano. Zaprezentowane powłoki kratowe o dobrych właściwościach strukturalnych mogą stanowić oryginalne przekrycia, natomiast analiza strukturalna ukierunkowana na wczesny etap projektowania ma na celu dostarczenie wytycznych projektowych ułatwiających komunikację między architektami i inżynierami.

19

Application of the input-output model for structural analysis on the example of the agricultural sector in Poland

Czyżewski A., Grzelak A.

Management

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2018

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Vol. 22, no. 2

285--298

EN

The main objective of the article is to recognize possibilities of use of the input-output model to structural assessments in the economy, with particular reference to the agricultural sector. The included considerations have a theoretical and application dimension related to the agricultural sector. Understanding the nature of structural changes and associated tendencies is particularly useful in shaping the economic policy of the state about the use of non-automatic economic stabilizers and the identification of areas that constitute development barriers. Analysis of the case of the agricultural sector in the input-output model, from the perspective of structural evaluation, indicate that there are evident transformations. It includes, in particular, the relative increase of links between agriculture and other branches, the growth in the importance of imports (supply), and the decline in the role of self-supply. It can be expected that these trends will deepen under conditions of economic development.

PL

Głównym celem artykułu jest rozpoznanie możliwości wykorzystania modelu przepływów międzygałęziowych do makroekonomicznych analiz strukturalnych w gospodarce, ze szczególnym uwzględnieniem sektora rolnego. Zawarte rozważania łączą wymiar teoretyczny z aplikacyjnym dotyczącym sektora rolnego. Zrozumienie charakteru zmian strukturalnych i tendencji z tym związanych jest szczególnie przydatne w kreowaniu polityki gospodarczej państwa w zakresie stosowania nieautomatycznych stabilizatorów koniunktury, jak i identyfikacji obszarów stanowiących bariery rozwojowe. Analiza przypadku sektora rolnego w modelu input-output z perspektywy ocen strukturalnych pozwala na stwierdzenie, że następują wyraźne przeobrażenia. Chodzi tu w szczególności o relatywne zwiększenie powiązań rolnictwa z pozostałymi działami, wzrost znaczenia importu (zaopatrzenia), przy spadku roli samozaopatrzenia. Można oczekiwać, że tendencje te pogłębiać się będą w warunkach rozwoju gospodarczego.

20

Porous Composite for Bipolar Plate in Low Emission Hydrogen Fuel Cells

Wlodarczyk R.

Journal of Ecological Engineering

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2018

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Vol. 19, nr 1

225--232

EN

The paper presents the results of graphite-stainless steel composites for the bipolar plates in low-temperature fuel cells. The sinters were performed by powder metallurgy technology. The influence of technological parameters, especially molding pressure were examined. Following the requirements formulated by the DOE concerning the parameters of the materials, it indicated by the value of the parameters. The density, flowability, particle size of graphite and stainless steel powders have been evaluated. Composites have been tested by microstructure and phase analysis, properties of strength, functional properties: wettability, porosity, roughness. The special attention was paid to the analysis of corrosion resistance obtained sinters and influence of technological parameters on the corrosion. Corrosion tests were carried out under conditions simulating the environment of the fuel cell under anode and cathode conditions. The effect of pH solution during working of the cell on corrosion resistance of composites have been evaluated. Contact resistance depends on roughness of sinters. Low ICR determined high contact area GDL-BP and high electrical conductivity on the contact surface. The ICR in anode conditions after corrosion tests are not change significantly; composite materials can be used for materials for BP in terms of H2.