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1

Analysis of the characteristics of magnetic properties change in the rock failure process

Zhang He, Sun Qiang, Zhenlong Ge

Acta Geophysica

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2020

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Vol. 68, no. 2

289--302

EN

It is difcult to observe changes in the internal structure of natural rocks when under certain pressure ranges. However, such rocks have specifc magnetic properties that are established during their formation process. Through studying changes in their magnetic properties while under pressure, which are readily observed and analyzed, as combined and contrasted with their associated structural changes, the relationship between the stress–strain and the magnetic feld intensity can be established. Based on the stress–strain and magnetic feld strength data obtained from the relevant literature, the process of rock and rock-like mechanical failure can be divided into three stages: elastic, plastic, and rupture. The performances of diferent rocks during these stages were analyzed, and there was an obvious transition point between any two adjacent stages. Thus, this study provides theoretical support to establish the relationship between structure and magnetic variations of rocks and rock-like bodies.

2

Metallurgical analysis of the causes of failure of the hardening furnace conveyor belt

Merda A., Klimaszewska K., Sroka M., Golański G.

Archives of Materials Science and Engineering

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2019

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Vol. 98, nr 2

68--73

EN

Purpose: The aim of the tests was to analyze the microstructure and mechanical properties of a section of the hardening furnace conveyor belt serviced at the temperature of 880-920°C in the carburizing atmosphere, in the context of determining the probable causes of its failure. Design/methodology/approach: The scope of performed tests included: chemical composition analysis of the steel and particles, microstructure investigated using optical and scanning electron microscopy, X-ray phase analysis. Findings: The analysis of the chemical composition showed that the examined material was austenitic steel X15CrNiSi25-21 (S310). Performed metallurgical tests showed that after the service the examined steel was characterized by austenitic structure with numerous precipitates of diverse morphology. In the structure the sigma phase particles and probably the M23C6 carbides precipitates were observed. The continuous grid of precipitates on the boundaries of grains (mainly the sigma phase) and the influence of the cyclic changing heat loads (or thermo-mechanical loads) were the main causes of failure of the analysed detail. Research limitations/implications: The aim of the work was to determine the probable causes of damage of the material used for a conveyor belt of a hardening furnace. Practical implications: The results of investigation and analysis of the metallographic of het-resisting austenitic steel X15CrNiSi25-21 (S310) after service at the temperature of 880-920°C are presented. Originality/value: The paper presents the results of research on the microstructure and mechanical properties of the section of hardening furnace conveyor belt made of creepresisting austenitic steel. The aim of the performed tests was to determine the probable causes of damage of the analysed detail.

3

Analysis of damage of the cooling aggregate in vehicle with cold storage chamber

Woźniak M., Batory D., Siczek K.

Journal of KONES

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2018

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Vol. 25, No. 1

475--482

EN

Vehicles with cold storage chambers realize the transport of fast spoil articles. The cooling system of such chamber is its critical subsystem, the essential component of which is a cooling aggregate driven by vehicle combustion engine via belt transmission. The main assembly of the analysed aggregate was the axial five-piston compressor. Small aluminum pistons were led in cylinders in fixed head made of aluminum alloy. Such pistons were driven through steel tappets, mating through their spherical surfaces with spherical seats made in small pistons. Through their front surfaces, placed opposite to the spherical surfaces, the spatial disc cam made of aluminum alloy drove small pistons. The cam was mounted on the steel shaft. The co-operation of described parts was in presence of refrigerant oil. The abrasive and fatigue wear of elements occurred. Because of long-term utilizing of the aggregate the damage of radial sealing ring occurred. Then, external impurities of high hardness got into the contact zone between the mating surfaces. The main aim of the study was to analyse consequences of such fact. The failure was noticed in the form of wear of disc cam, front surfaces of tappets, and the plastic deformation in the spherical surfaces of the seats. Then, due to deformation and the displacements of the rotating shaft, wear of the side surface of disc cam during contacts with small pistons surfaces took place. Moreover, we noticed wear of the side surfaces of the pistons and the cylinders mating with them in the fixed head. In the article, we present figures of damaged surfaces of elements and results of the SEM analysis of spherical surfaces of tappets. The material transfer occurred between the spherical surfaces of tappets and their seats.

4

Evaluation of the Damage Initiation of a Composite Thin-Walled Structure, on the Example of the ADUSTER Gyroplane Undercarriage

Szklarek Karol, Różyło Patryk

Advances in Science and Technology. Research Journal

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2018

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Vol. 12, no 4

48--55

EN

The subject of the research was a undercarriage leg of a gyroplane made of composite materials. The aim of the work was to assess the level of damage initiation of the composite gyroplane undercarriage. In the study, a structural capacity analysis was carried out, taking into account the phenomenon of damage initiation. Numerical calculations were conducted based on the finite element method in the ABAQUS® software. The issue was solved according to the Newton-Raphson algorithm.

5

Acoustic camera as a tool for identifying machinery and equipment failures

Pavlikova Ľudmila, Hricová Beata, Lumnitzer Ervín

Advances in Science and Technology. Research Journal

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2018

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Vol. 12, no 1

322--328

EN

Sound and noise are as old as humanity itself. They have accompanied civilization, evolution, and development for centuries. Music and speech represent not only the key elements of human life but also unpleasant feelings of noise that have always been an integral part of human existence. As industrial development has required more energy, powerful machinery, and equipment, there have been still noisier machines. Traffic has grown quickly due to the number and speed of vehicles. For that reason, an acoustic camera is used for the dynamic visualization of machinery and equipment noise as it analyses the sources of noise in details. Subsequently, qualified measures are introduced based on the results of the analysis. The paper considers launching another application. According to the proposed methodology, its use in identifying machinery and equipment failures and their maintenance is proved. The experiment was performed on a four-wheel lawn mower. The primary focus was on the identification of failures using an acoustic camera. The previous method allowed to quickly, precisely and efficiently identifying the failures in two out of five tested machines.

6

Evaluation of Strength and Failure of Brittle Rock Containing Initial Cracks under Lithospheric Conditions

Li X., Qi C., Shao Z., Ma C.

Acta Geophysica

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2018

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Vol. 66, no. 2

141--152

EN

Natural brittle rock contains numerous randomly distributed microcracks. Crack initiation, growth, and coalescence play a predominant role in evaluation for the strength and failure of brittle rocks. A new analytical method is proposed to predict the strength and failure of brittle rocks containing initial microcracks. The formulation of this method is based on an improved wing crack model and a suggested micro-macro relation. In this improved wing crack model, the parameter of crack angle is especially introduced as a variable, and the analytical stress-crack relation considering crack angle effect is obtained. Coupling the proposed stresscrack relation and the suggested micro-macro relation describing the relation between crack growth and axial strain, the stress-strain constitutive relation is obtained to predict the rock strength and failure. Considering different initial microcrack sizes, friction coefficients and confining pressures, effects of crack angle on tensile wedge force acting on initial crack interface are studied, and effects of crack angle on stress-strain constitutive relation of rocks are also analyzed. The strength and crack initiation stress under different crack angles are discussed, and the value of most disadvantaged angle triggering crack initiation and rock failure is founded. The analytical results are similar to the published study results. Rationality of this proposed analytical method is verified.

7

Przyczyny niedostatecznych efektów partnerstwa publiczno-prywatnego w realizacji celów publicznych

Biliński T.

Przegląd Budowlany

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2014

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R. 85, nr 2

30--32

PL

W artykule przedstawiono genezę powstawania przepisów prawnych dotyczących koncesji na roboty budowlane lub usługi. Przekonanie, że instytucja partnerstwa publiczno-prywatnego przyniesie dużo korzyści społeczno-gospodarczych nie sprawdziło się. Efekty współdziałania podmiotów publicznych i prywatnych w realizacji celów publicznych były niewystarczające. Uchwalenie ustawy o koncesji na roboty budowlane lub usługi nie przyniosło oczekiwanych efektów. Nieliczne przykłady zrealizowanych przedsięwzięć inwestycyjnych nie są satysfakcjonujące. Trudne jest zatem ustalenie zasadniczych przyczyn takiego stanu. Wymienione w artykule przyczyny mogą stanowić podstawę do dalszych studiów nad oceną dotychczasowych efektów partnerstwa publiczno-prywatnego.

EN

The paper presents the origins of creation of legal regulations concerning the concession for construction works or services. The conviction that the public-private partnership will bring numerous social and economic benefits did not come true. The results of cooperation between public and private entities in achieving public objectives were insufficient. Adoption of the act on concession for construction works or services did not bring the expected results. Scarce examples of realized investment projects are not satisfactory. Thus, the determination of causes underlying such a state of affairs remains difficult. The causes enumerated in the paper might constitute a basis for further research on the assessment of the results of the public-private partnership achieved so far.

8

Sukces projektu: kryteria pomiaru, definicje

Urbanelis R.

Gospodarka Materiałowa i Logistyka

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2014

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nr 1

18--26

PL

Istnieje wiele publikacji traktujących o czynnikach sukcesu projektu: autorzy przedstawiają badania, ankiety i szeregują czynniki od najbardziej istotnych, grupują je i klasyfikują. Jednocześnie bardzo niewiele publikacji definiuje sukces lub niepowodzenie projektu jako takie lub omawia kryteria, którymi mierzony będzie ów sukces. Niniejsza praca systematyzuje obecny stan wiedzy i podejście autorów do interpretacji i kryteriów sukcesu: omawia rolę trójkąta projektowego w definicji sukcesu, przytaczając jednocześnie kontrprzykłady w tym zakresie. Pokazuje, jak koncepcja sukcesu zmieniała się przez ostatnie dziesiątki lat, a następnie – jak ocena sukcesu bądź niepowodzenia tego samego projektu może zmieniać się w ujęciu czasowym i jak odnieść ją do poziomu operacyjnego, taktycznego i strategicznego organizacji. Na końcu publikacji autor postuluje kompromisowe i „miękkie” podejście do definicji sukcesu oparte na konkretnych grupach kryteriów, ale również narracji, retoryce czy upływie czasu.

EN

There have been a lot of papers discussing project success factors: numerous authors present research results, pools, and putting success/failure factors in order of importance, or grouping them and classifying them. At the very same time, there’re only a few papers that define project success or failure per se, or discuss criteria how that success will be measured. This paper brings up current knowledge status, and author’s approach to interpretation of the success criteria: it discusses role of project’s triangle in definition of success, showing also counterexamples in this matter. It shows how the concept of success evolved over the years, then how judgment of the very same project can change in time, and how to map this judgment to operational, tactical and strategic levels of the organization. At the end of the paper, author postulate compromised and “soft” approach to project success definition, on one side based on clearly pre-defined groups of criteria, but on the other side based on narration, rhetoric and flow of time.

9

The causes of the failure of organizational changes in the light of empirical research

Skalik J.

Management

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2006

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Vol. 10, no 1

27-32

EN

Change is the only stable thing in the reality of an organization. The necessity to introduce changes is generally accepted and strongly supported by organization theorists. It often happens in practice that there are frequent diversions from advice provided by the theory, which is the reason for the failure of organizational changes. Its causes and results have been specified on the basis of empirical research and presented in this article.

PL

Jedynie stałą rzeczą w rzeczywistości organizacji jest zmiana. Konieczność ich wprowadzania jest powszechnie akceptowana i mocno wspierana przez teoretyków organizacji. W praktyce zauważa się dość częste odstępstwa od zaleceń teorii co jest przyczyną niepowodzeń zmian organizacyjnych. Ich istota i skutki zostały określone na podstawie badań empirycznych i przedstawione w treści niniejszego artykułu.