Temat: mechanical impact - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Changes in the quality characteristics of raspberry fruit due to mechanical vibrations and storage conditions
Autorzy:: Mazur, Jacek
Panasiewicz, Marian
Zawiślak, Kazimierz
Sobczak, Paweł
Nadulski, Rafał
Łysiak, Grzegorz
Kraśnicka, Kinga
Tematy:: raspberry fruits
mechanical impact
juice leakage; Pokaż więcej
Wydawca:: Uniwersytet Warmińsko-Mazurski w Olsztynie
Powiązania:: https://bibliotekanauki.pl/articles/298046.pdf Link otwiera się w nowym oknie
Opis:: The paper presents the results of a study investigating a mechanical impact, in the form of vibrations, on the overall quality of raspberry fruits after harvest, in view of the conditions of their transport to the consumer and the processing plant. The degree of compaction of the raspberry fruit layer was determined during a test carried out under laboratory conditions, and the amount of juice leakage, resulting from the vibrations to which the raspberries were subjected, was measured. It was demonstrated that the quantity (mass) of juice leakage was considerably affected by the mechanical impact, in the form of vibrations, exerted on a layer of raspberry fruits. The leakage was smaller in cooled fruits, and significantly greater in fruits that were not subjected to cooling immediately after harvest, and were stored under ambient conditions.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Influence of moisture content and number of mechanical impacts, upon the energy and sprouting capacity of wheat grains
Autorzy:: Fraczek, J.
Slipek, Z.
Tematy:: transport
sprouting capacity
mechanical impact
wheat
grain
moisture content
harvest
cleaning
energy; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Agrofizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/25234.pdf Link otwiera się w nowym oknie
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Zagadnienia trwałości pokryć dachowych w głównych budynkach elektrowni
Autorzy:: Hotała, Eugeniusz
Tematy:: oddziaływanie mechaniczne
oddziaływanie termiczne
uszkodzenie
trwałość
pokrycie dachowe
pokrycie papowe
odporność
pianka poliuretanowa
budynek elektrowni
mechanical impact
thermal impact
damage
durability
roof cover
tar paper covering
resistance
polyurethane foam
power plant building; Pokaż więcej
Wydawca:: PWB MEDIA Zdziebłowski
Powiązania:: https://bibliotekanauki.pl/articles/129403.pdf Link otwiera się w nowym oknie
Opis:: Pokrycia dachowe głównych budynków elektrowni narażone są na różne niekorzystne oddziaływania mechaniczne i termiczne. W wielu przypadkach pokrycia te ulegają dość szybkiemu zużyciu lub różnorodnym uszkodzeniom. W pracy zaprezentowano niektóre przypadki uszkodzeń dachowych pokryć papowych oraz pokryć z pianki poliuretanowej (PUR) w budynkach kotłowni i maszynowni oraz w innych budynkach. Szczególną uwagę zwrócono na dużą wrażliwość pokryć z pianki PUR na czynniki mechaniczne i termiczne. Wskazano na potrzebę badań odporności pianek poliuretanowych na specyficzne czynniki występujące w dachach budynków elektrowni.
Roof coverings of the main power plant buildings are exposed to various adverse mechanical and thermal impacts. In many cases, these coverings wear out quite quickly or are damaged in various ways. The paper presents some cases of damage of tar paper coverings and polyurethane (PUR) foam coverings in boiler room and engine room buildings and other buildings. Special attention was paid to high sensitivity of PUR foam coverings to mechanical and thermal factotors. The need to test the resistance of polyurethane foams to specific factors occurring in the roofs of power plant buildings was indicated.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Autorzy:: Gnecco, Enrico
Khaksar, Hesam
Der, Oguzhan
Opis:: The invasive presence of nanoplastics in various ecosystems makes them a significant environmental problem nowadays. One of the main production mechanisms of nanoplastics is mechanical wear. The combination of friction, abrasion, and shear forces can indeed lead to the progressive fragmentation of polymeric materials. The high surface area–volume ratio of the resulting nanoparticles not only alters the physicochemical properties of the polymers but also leads to increased interaction with biological systems, which raises questions about the persistence of nanoplastics in the environment and their potential toxicity. Despite the growing body of research on microplastics, studies specifically addressing the formation, characterization, and impact of wear-induced nanoplastics remain limited. This article describes current research on the formation mechanisms of nanoplastics generated by mechanical wear, highlighting the tribological processes underlying their release. Advanced characterization techniques used to identify the morphology and composition of these particles are also mentioned. The techniques include atomic force microscopy (AFM), scanning electron microscopy (SEM), and, to some extent, Raman spectroscopy. In the case of AFM, an example of application to the extrusion of nanoplastics from polystyrene surfaces subjected to repeated nanoscratching is also provided.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 5.

Tytuł:: Vibroacoustic Helicopter Impact on Elevated Helipad
Autorzy:: Cieślak, Sławomir
Krzymień, Wiesław
Tematy:: mechanical engineering
helipad
helicopter
noise
vibrations
impact; Pokaż więcej
Wydawca:: Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
Powiązania:: https://bibliotekanauki.pl/articles/36809460.pdf Link otwiera się w nowym oknie
Opis:: A helicopter landing and taking off on an elevated helipad is a source of noise that affects the environment and causes vibrations of the landing pad or the building infrastructure. Vibrations are also excited by the air stream flowing through the main rotor and transferred to the landing pad by contact of the helicopter chassis. Vibrations are transferred to the building through the structure of the helipad. Depending on the damping properties of the structure and the vibro-isolating elements used, vibrations can be felt in rooms used by people and also transmitted to devices located in the building. The subject of the study described in this paper is the vibroacoustic effects of an EC-135 helicopter on an elevated landing pad during landing, standstill with the propulsion system engaged and take-off. Measurements of vibrations and noise were made at points located both on the landing pad and in the building. The paper presents selected results of measurements in various phases of flight and helicopter manoeuvres. The frequency analyses of the fragment of the measurement data for the flight phase, in which the highest levels of impact were recorded, were also performed and included. The results are presented as graphs and annotated.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Experimental and analytical approaches on air spring absorbers made of ldpe polymer
Autorzy:: Obst, Maciej
Kurpisz, Dariusz
Jakubowski, Michał
Tematy:: LDPE absorbers
reaction on impact
analytical approach
mechanical parameters
impact test
LDPE bellows impact
protective; Pokaż więcej
Wydawca:: Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Powiązania:: https://bibliotekanauki.pl/articles/58907255.pdf Link otwiera się w nowym oknie
Opis:: Damping and energy-consuming elements can be found in many technical applications. This means these component types can prevent fractures or injuries in the case of products or people, respectively. In the last time, many modern applications and inventions associated with the reduction of the effects of an impact are observed especially in the mode of transportation safety area. The significant development of the automotive industry, increasing popularity of motorbikes, electric bikes and scooters, sports field, etc., require new solutions for personal safety protection. Human head and neck protection, and other body parts protection are typical groups of solutions from biomechanics and mechanical engineering. Authors have investigated LDPE-made pneumatic absorbers under axial impact force. Based on the experimental approach and analytical model, mechanical characteristics are presented. Impact force value, deceleration and damping for different loading conditions are shown. Because safety systems’ impact protective features can be matched to impact conditions, results indicated that absorber damping could possibly be a good solution for them, shaping the impact characteristics according to safety requirements.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Collision modeling of single unit impact absorber for mechanical systems vibration attenuation
Autorzy:: Chehaibi, Kaouther
Mrad, Charfeddine
Nasri, Rachid
Tematy:: mechanical system
single unit impact absorber
collision modeling; Pokaż więcej
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Powiązania:: https://bibliotekanauki.pl/articles/281907.pdf Link otwiera się w nowym oknie
Opis:: A single unit impact absorber is a ball absorber located in a mechanical system to attenuate its undesirable vibration. The absorber has a free motion constrained by stops. Collisions between the main system and the absorber masses help to dissipate kinetic energy as heat, noise and high frequency vibrations and thus reducing the main system dynamic response. However, the collisions give rise to discontinuity and strong nonlinearity. This work intends to study the effect of the collision modeling on the absorber efficiency. The contact force-based linear viscoelastic model of Hook-Newton, nonlinear elastic model of Hertz, and nonlinear viscoelastic model proposed by Hunt and Crossley are considered. For each case, analytical study is conducted to determine the equations of motion. The system responses are obtained for forced vibration, considering the whole ball motion cycle: left impact-free motion-right impact and following a numerical resolution based on the Newmark method. Finally, comparison of different impact models is made to conclude on the single unit impact absorber performance.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Low-velocity impact behaviour of open-cell foams
Autorzy:: Hedayati, R.
Sadighi, M.
Tematy:: open-cell foam
low-velocity impact
biomaterial
mechanical properties; Pokaż więcej
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Powiązania:: https://bibliotekanauki.pl/articles/949323.pdf Link otwiera się w nowym oknie
Opis:: Metal foams are cellular solids that show some unique properties which cannot be found in other natural or human-made materials. While the impact characteristics of closed-cell foams under static and impact loadings appear to be well-studied in the literature, the impact behaviour of open-cell foams is not yet well-understood. In this study, open-cell foams with two different densities are impacted by drop weights with different kinetic energies. The effects of foam density, impactor initial height, and impactor weight on the recorded stresstime, stress-strain, and energy-strain curves are investigated. While the stress-strain curve of closed-cell foams under impact loading usually consists of a single bell, the results of the current study showed that both the stress-time and stress-strain curves of most the samples consist of two consecutive bells. By increasing weight of the impacting weight, the number of bells increases which helps in increasing the impact period and keeping the maximum generated stress low. Compared to closed-cell foams, the open-cell foams can therefore better absorb the energy, as long as the impact energy is relatively small. The relatively low stiffness as well as the presence of large hollow space inside the open-cell foams also makes them favorable for being used as biomedical scaffolds.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Measurement of Short-Circuit Effects on Transformer Winding with SFRA Method and Impact Test
Autorzy:: Gutten, M.
Janura, R.
Šebök, M.
Korenčiak, D.
Kučera, M.
Tematy:: transformer
mechanical effects
measuring methods
frequency response
impact test; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/221649.pdf Link otwiera się w nowym oknie
Opis:: The paper presents theoretical and experimental analyses of a possible effect of the short-circuit forces on the transformer winding. The first part of the paper is focused on creation and activity of the radial and axial forces during a short circuit. It shows dimensions, direction and − of course − the resulting mechanical stress. The presented equation shows basic dependencies of these mechanical forces created in the transformer winding. Finally, the paper presents experimental methods of diagnosing and analysing the effects of short-circuit forces on the transformer winding.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Środowiskowe aspekty uszczelnień czołowych w przemyśle browarniczym
Environmental aspects of mechanical seal failures in the brewing industry
Autorzy:: Kasprzak, J.
Rewolińska, A.
Tematy:: uszczelnienie czołowe
uszkodzenie
oddziaływanie środowiskowe
mechanical seal
failure
environmental impact; Pokaż więcej
Wydawca:: Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Powiązania:: https://bibliotekanauki.pl/articles/2072541.pdf Link otwiera się w nowym oknie
Opis:: W pracy omówiono problem następstw użytkowania uszczelnień czołowych stosowanych w pompach wirowych w przemyśle browarniczym. Przedstawiono szerszy kontekst stosowania uszczelnień czołowych w przemyśle spożywczym, jak również dokonano analizy literatury w aspekcie eksploatacyjnych uszkodzeń uszczelnień czołowych w tej gałęzi przemysłu. Problematykę tę rozszerzono o zagadnienia oddziaływania na środowisko - opisano powszechnie stosowaną metodykę wartościowania oddziaływań środowiskowych oraz - jako przykład - przedstawiono studium przypadku, dotyczące środowiskowej analizy wybranego typu uszczelnienia czołowego.
Issues of mechanical seal failures used in impeller pumps in the brewing industry are described in the paper. A wider context of application of mechanical seals in the food industry is shown, together with the literature analysis concerning mechanical seal failures. These topic was extended to environmental impact issues - commonly applied methods of environmental evaluation of technical objects are described. A case study of environmental analysis of chosen mechanical seal is shown as an example.
Dostawca treści:: Biblioteka Nauki

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