Skocz do pozycji: 1.

Tytuł:

Experimental study on dynamic structure of propeller tip vortex

Autorzy:

Li, Guangnian
Chen, Qingren
Liu, Yue

Powiązania:

https://bibliotekanauki.pl/articles/260305.pdf

Data publikacji:

2020

Wydawca:

Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa

Tematy:

propeller
blade tip
tip vortex
PIV

Opis:

Propeller cavitation is a main source of fluctuating pressure and noise induced by propellers, and the tip vortex cavitation is the principal source. The present study measures the flow fields near the blade tip using the 2D-PIV technique. The experimental setup and scheme are introduced. We monitor the process of generation and shedding of the propeller tip vortex in real time and analyse the dynamic structure of the tip vortex by testing the propeller wake field under different phases of the axial plane. The distribution characteristics of radial and axial velocity are also analysed. The influence range and the vorticity of the tip vortex and trailing vortex are obtained. All of the measured quantitative data are useful for future propeller design.

Źródło:

Polish Maritime Research; 2020, 2; 11-18
1233-2585

Pojawia się w:

Polish Maritime Research

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 2.

Tytuł:

The unsteadiness of tip clearance flow and its effect to stability of transonic axial compressor
Nieustaloność przepływu w szczelinie wierzchołkowej i jej wpływ na stabilność pracy przydźwiękowej sprężarki osiowej

Autorzy:

Hu, J. F.
Zhu, X. C.
Ou-Yang, H.
Tian, J.
Wu, Y. D.
Qiang, X. Q.
Zhao, G.
Du, Z. H.

Powiązania:

https://bibliotekanauki.pl/articles/281445.pdf

Data publikacji:

2013

Wydawca:

Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej

Tematy:

tip leakage flow
compressor
stability

Opis:

The steady and unsteady RANS simulations of a transonic compressor rotor (NASA rotor 37) are performed to investigate the tip clearance flow characteristic and correlations between tip leakage flow and compressor stability. For steady simulations, the results are compared with the aerodynamic probe and laser anemometer data. The speed lines and span-wise aerodynamic parameters agree well with the experimental data. On the other hand, the tip clearance flow of unsteady simulations are analysed clearly at a near stall condition. The results show that there is a mass flow rate boundary. The tip clearance flow oscillates substantially with a frequency about 50% BPF when the mass is less than that, which is caused by tip clearance flow, shock, and the interaction between them and the oncoming flow. The interface between the oncoming flow and clearance flow shifts forward, and the tip clearance flow may spill over into the adjacent blade passage as the mass flow decreases, which may results in the spike stall inception.
W pracy przedstawiono symulacje stanu ustalonego i nieustalonego przydźwiękowej sprężarki osiowej (turbina NASA 37) z zastosowaniem metody Reynoldsa uśredniania równań Naviera-Stokesa (RANS) w celu zbadania charakterystyki przepływu w szczelinie wierzchołkowej oraz określenia zależności pomiędzy stratami związanymi z upływem w tej szczelinie a stabilnością pracy sprężarki. Wyniki symulacji stanu ustalonego porównano z danymi doświadczalnymi uzyskanymi za pomocą sondy aerodynamicznej i laserowego wiatromierza. Wyznaczone wzdłuż rozpiętości sprężarki linie prędkości przepływu i jego parametry aerodynamiczne okazały się zgodne z danymi doświadczalnymi. W przypadku symulacji stanu nieustalonego, analizę przepływu w szczelinie wierzchołkowej przeprowadzono dla warunków bliskich oderwania, tj. utraty wydajności sprężarki, wyznaczając graniczny wydatek przepływu dla takiej sytuacji. Poniżej tej granicznej wartości, zmiany przepływu w szczelinie oscylują z częstotliwością sięgającą 50% częstotliwości przejścia łopatek (tzw. BPF), co jest konsekwencją interakcji wywołanej zderzeniem przepływu z falą napływową w szczelinie wierzchołkowej. Powierzchnia tej interakcji przesuwa się do przodu, a sam przepływ może rozpaść się na fragmenty znajdujące ujście w kanałach przyległych łopatek. Zjawisko to zachodzi przy malejącym wydatku, a to z kolei może indukować oderwanie przepływu skokowymi zmianami mocy współpracującego silnika.

Źródło:

Journal of Theoretical and Applied Mechanics; 2013, 51, 2; 431-438
1429-2955

Pojawia się w:

Journal of Theoretical and Applied Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 3.

Tytuł:

Nano-hardness of the material of thin layers of the injector tip depending on the depth under the precisly finished co-operating surfaces

Autorzy:

Miszczak, A.
Kuznetsova, T.
Czaban, A.

Powiązania:

https://bibliotekanauki.pl/articles/243108.pdf

Data publikacji:

2015

Wydawca:

Instytut Techniczny Wojsk Lotniczych

Tematy:

nanohardness
Young's modulus
nano-identer
injector tip nozzle
injector spray pattern
injector tip needle

Opis:

In this paper, the authors present the results of experimental studies of the nano-hardness and Young's modulus of the injector spray pattern body and needle (the tip of the injector). The nano-hardness of a thin-layer of precisely finished co-operating surfaces was tested according to the depth below the surface of the sample (deep into the material). The quality of precisely finished surfaces of a fuel infector has a very large impact on the proper operation of a diesel engine. Both, the needle and the body of the injector spray pattern, are individually adjusted and lapped to maintain the proper gap between them. The gap between the needle and the injector tip body affects the proper dosage and quality of the sprayed fuel. Impurities in the fuel are of the same order of magnitude or even greater than this gap. Hard particles that penetrate between the side surfaces of the needle and body of the injector tip could result in scratching, which generate leaks and drops of injection pressure, increased fuel consumption, poor spraying of fuel, leaking of fuel to the lubricating oil and reduction of its operating properties. The hardness of the precisely finished surfaces of the injector is essential in the process of wear of these surfaces. The aim of the study was to determine the hardness and Young's modulus of thin layers of precisely finished co-operating surfaces of injector tip and estimation of the thickness of these layers. The nano-hardness measurements were made with the Hysitron TI 950 TriboIdenter, where the test is conducted using a nano-indenter with a mechanical method. The device allows selecting from several to several dozen of measurement points and performs automatic measurement of nano-hardness and Young's modulus in the indicated locations. The study concerns the tip (body and needle) of the non-used Bosch DLLA 160 S 1305 injector. The presented results can be used to develop some new methods of coating the co-operating surfaces with the hard thin layers, e.g. the use of titanium in order to decrease wear and increase scratching resistance.

Źródło:

Journal of KONES; 2015, 22, 3; 155-160
1231-4005
2354-0133

Pojawia się w:

Journal of KONES

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 4.

Tytuł:

Two dimensional model of CMM probing system

Autorzy:

Ali, Salah H.R.

Powiązania:

https://bibliotekanauki.pl/articles/950738.pdf

Data publikacji:

2010

Wydawca:

Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów

Tematy:

CMM
trigger probe
stylus tip
tip root errors
and two-dimensional-model (2DM)

Opis:

A coordinate measuring machine (CMM) as an automation technology is playing the key role in the modern industry to improve the measurement accuracy. Accurate probing that is computer controlled is the current trend for the next generation of coordinate metrology. However, the CMM probing system is limited by its dynamic root errors that may markedly affect its response characteristics. In this paper, dynamic response errors of CMM measurements have been analyzed. The adopted probe stylus sizes throughout the course of measurements are found to cause some waviness errors during CMM operations due to each of the prescribed angle of the probe tip contact point with the specimen surface and the radius of the stylus tip. Variations in the geometry of the stylus have their consequent effects on its inherent intrinsic dynamic characteristics that in turn would cause relevant systematic root errors in the resulted measurements. Unforeseeable geometrical errors of a CMM using a ductile touch-trigger probing system have been characterized theoretically. These results are analyzed in order to investigate the effect of the dynamic root errors in the light of six probe stylus tip of the situation into account when assessing the accuracy of the CMM measurements. Analytical approaches have been applied on a developed two dimensional model (2DM) of stylus tip to demonstrate the capability of such approaches of emphasizing the root error concept using the strategy of CMM ductile trigger type of probe.

Źródło:

Journal of Automation Mobile Robotics and Intelligent Systems; 2010, 4, 2; 3-7
1897-8649
2080-2145

Pojawia się w:

Journal of Automation Mobile Robotics and Intelligent Systems

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 5.

Tytuł:

Development of an on-line damage detection, discrimination and tracking system for the spin rig facility

Autorzy:

Przysowa, R.
Bereś, W.
Carnegie, C.

Powiązania:

https://bibliotekanauki.pl/articles/241879.pdf

Data publikacji:

2017

Wydawca:

Instytut Techniczny Wojsk Lotniczych

Tematy:

disc crack
disc health monitoring
vacuum spin testing
tip timing
tip clearance
low cycle fatigue

Opis:

The main goal of the work reported here was to expand the capability of the NRC-Aerospace spin rig by adding an on-line damage detection, discrimination and tracking system, and to develop necessary expertise that will allow for optimizing the NDE inspection periods of gas turbine engine components in this facility and minimizing undetected crack nucleation and growth and possibility of catastrophic failures. Passive eddy-current sensors and a data acquisition system able to simultaneously measure blade deflection and tip clearance were selected to monitor health of rotating components. Before application of the system in the spin rig, the system was tested with a rotor rig to check sensor responses to deliberately induced changes in blade tip positions in both radial and circumferential directions. The monitored disc had 12 bolts simulating aerofoils that could be turned into threaded holes to extend or shorten the protruding parts of the bolts. On the other hand, bolt vibration was not excited and analysed during the experiment. Lessons learned on the rotor rig are used to prepare and plan spin tests in vacuum chamber.

Źródło:

Journal of KONES; 2017, 24, 2; 197-209
1231-4005
2354-0133

Pojawia się w:

Journal of KONES

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 6.

Tytuł:

Uyghurs of Syria: Significance for the Syrian Conflict and International Implications
Ujgurzy w Syrii – znaczenie dla konfliktu syryjskiego i implikacje międzynarodowe

Autorzy:

Mazur, Przemysław

Powiązania:

https://bibliotekanauki.pl/articles/22435850.pdf

Data publikacji:

2023-09-30

Wydawca:

Wydawnictwo Adam Marszałek

Tematy:

Uyghurs
Syria
terrorism
Turkey
China
ISIS
Turkistan Islamic Party (TIP)
Ujgurzy
TIP
terroryzm
Turcja
Chiny

Opis:

The main objective of the article was to determine whether the Uyghurs were a relevant group in the Syrian conflict, i.e., whether they were numerous, well-organized and determined enough to take the fight to the Syrian army or other non-state actors or cooperate with them. Several levels of analysis were carried out in this article. Firstly, article aimed to show where the Uyghurs in Syria came from. Secondly, the following section assessed their importance to the Syrian conflict, as well as who they worked with and fought against. Thirdly, it analysed whether their military and political involvement could have an impact on the international situation. Last but not least, the fate of Uyghurs, especially those who left for Syria, was discussed. The latter issue is also a question about Syria, its fate and place in the politics of other countries.
Głównym celem artykułu było ustalenie, czy Ujgurzy byli istotną grupą w konflikcie syryjskim, innymi słowy – czy byli na tyle liczni, dobrze zorganizowani i zdeterminowani, by podjąć walkę z wojskami syryjskimi czy innymi aktorami niepaństwowymi lub z nimi współpracować. W artykule przeprowadzono analizę na kilku poziomach. Po pierwsze, artykuł miał na celu ustalenie, z jakich przyczyn Ujgurzy wyemigrowali do Syrii. Po drugie, oceniono ich znaczenie dla konfliktu syryjskiego, a także to, z kim współpracowali i z kim walczyli. Po trzecie, przeanalizowano, czy ich militarne i polityczne zaangażowanie może mieć wpływ na sytuację międzynarodową. Na koniec omówiono losy Ujgurów, zwłaszcza tych, którzy wyjechali do Syrii. To ostatnie zagadnienie stanowi też pytanie o Syrię, jej dalsze losy i miejsce w polityce innych państw.

Źródło:

Athenaeum. Polskie Studia Politologiczne; 2023, 79; 194-214
1505-2192

Pojawia się w:

Athenaeum. Polskie Studia Politologiczne

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 7.

Tytuł:

Numerical study of stall inception in a transonic axial compressor rotor based on the throttle model

Autorzy:

Zhu, X.
Liu, B.
Hu, J.
Shen, X.

Powiązania:

https://bibliotekanauki.pl/articles/280516.pdf

Data publikacji:

2015

Wydawca:

Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej

Tematy:

stall
axial compressor
throttle
tip clearance flow

Opis:

The goal of the current paper is to investigate inner flow behavior on stall inception in a transonic compressor rotor. The stall inception process is numerically carried out by unsteady 3-D simulations based on the throttle model. The current study shows that stall starts from the tip of the blade, and stall cell extends to the axial, circumferential and radial directions. Through the comparison of flow transition characteristics at different flow rate conditions, the interface between the incoming flow and tip clearance flow shifts forward to the upstream as the mass flow decreases. Eventually, the shock detaches from the blade leading edge, and tip clearance flow spills into the adjacent blade passage, thus stall happens in the affected blade passages.

Źródło:

Journal of Theoretical and Applied Mechanics; 2015, 53, 2; 307-316
1429-2955

Pojawia się w:

Journal of Theoretical and Applied Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 8.

Tytuł:

Dynamic interaction of the cavitating propeller tip vortex with the rudder

Autorzy:

Szantyr, J. A.

Powiązania:

https://bibliotekanauki.pl/articles/260364.pdf

Data publikacji:

2007

Wydawca:

Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa

Tematy:

propeller blades
rudder
cavitating
tip vortex shed

Opis:

The hydrodynamic interaction between the ship propeller and the rudder has many aspects. One of the most interesting is the interaction between the cavitating tip vortex shed from the propeller blades and the rudder. This interaction leads to strongly dynamic behaviour of the cavitating vortex, which in turn generates unusually high pressure pulses in its vicinity. Possibly accurate prediction of these pulses is one of the most important problems in the hydrodynamic design of a new ship. The paper presents a relatively simple computational model of the propeller cavitating tip vortex behaviour close to the rudder leading edge. The model is based on the traditional Rankine vortex and on the potential solution of the dynamics of the cylindrical sections of the cavitating kernel passing through the strongly variable pressure field in the vicinity of the rudder leading edge. The model reproduces numerically the experimentally observed process of initial compression of the vortex kernel in the high pressure region near the stagnation point at the rudder leading edge and subsequent explosive growth of the kernel in the low pressure region further downstream. Numerical simulation of this process enables computation of the additional pressure pulses generated due to this phenomenon and transmitted onto the hull surface. This new numerical model of the cavitating tip vortex is incorporated in the modified unsteady lifting surface program for prediction of propeller cavitation, which has been successfully used in the process of propeller design for several years and which recently has been extended to include the effects of propeller – rudder interaction. The results of calculations are compared with the experimental measurements and they demonstrate reasonable agreement between theory and physical reality.

Źródło:

Polish Maritime Research; 2007, 4; 10-14
1233-2585

Pojawia się w:

Polish Maritime Research

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 9.

Tytuł:

Optimization of tip seal with honeycomb land in LP counter rotating gas turbine engine

Autorzy:

Wróblewski, W.
Dykas, S.
Bochon, K.
Rulik, S.

Powiązania:

https://bibliotekanauki.pl/articles/1943216.pdf

Data publikacji:

2010

Wydawca:

Politechnika Gdańska

Tematy:

tip seal
LP turbine
honeycomb land
optimization

Opis:

The goal of the presented work is an optimization of the geometrical configuration of the tip seal with a honeycomb land, to reduce the leakage flow in the counter-rotating LP turbine of a contra-rotating open rotor aero-engine. This goal was achieved with the use of the Ansys-CFX commercial code and an in-house optimization procedure. The detailed studies including the mesh influence, the stages of the computational domain simplification, and geometry variants are discussed. The optimization process is based on a single objective genetic algorithm (SOGA). The automatic grid generation process and the CFD calculations are based on scripts prepared under the Ansys-ICEM and Ansys-CFX software. The whole procedure is written in the Visual Basic for Applications language (VBA), which allows a direct access to the CAD software with the use of macros and allows a proper connection between the CAD environment and the CFD software. The described algorithm allows parallel computing. In addition to the optimization studies, a sensitivity analysis was also performed. For this purpose, the Elementary Effects Method (EEM) was used. This paper was written within the DREAM European project (Validation of Radical Engine Architecture Systems) of the 7th Framework Program of the European Union.

Źródło:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2010, 14, 3; 189-207
1428-6394

Pojawia się w:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 10.

Tytuł:

Study of topology and vortex structure in turbine cascades with tip clearance under different incidence angles
Badania topologii i struktury wirów palisady turbiny z luzem wierzchołkowym przy różnych kątach natarcia

Autorzy:

Yan, P. G.
Qiang, X. Q.
Teng, J. F.
Han, W. J.

Powiązania:

https://bibliotekanauki.pl/articles/279519.pdf

Data publikacji:

2013

Wydawca:

Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej

Tematy:

turbine cascade
tip clearance
topological rules
experimental study

Opis:

Three sets of conventional straight, positive curved and negative curved turbine cascades with tip clearance were tested with experimental measurement. The impact of incidence angles and blade bending on the tip leakage was studied under larger clearance (0.036 of span). An ink trace visualization of the wall flow and topology theory was adopted and thus the topological structures of the blade surface, the upper and lower end wall were analyzed in this paper. It was found that, compared with the same cascade under the zero incidence angle, the saddle points all move to the upstream, the scope of the separation expands along the flow and span direction, and the separation line of the upper and lower passage vortex climb to the middle span of the blade when the flow incidence angle increased from zero to 20º. Under the condition of zero and 20º incidence angle, the positive curved blade will eliminate the upper passage vortex. The numbers of singular points are reduced and the interaction loss between the passage vortex and the leakage vortex is greatly reduced too. On the other hand, it also strengthens the blocking effect of the end wall cross flow on the leakage flow, thereby reduces the relative leakage flow rate.
W pracy zaprezentowano wyniki pomiarów eksperymentalnych trzech zestawów konwencjonalnych palisad turbin o prostym, dodatnio i ujemnie zakrzywionym profilu. Zbadano wpływ kąta natarcia oraz efekt zginania łopatek na straty wskutek upływu przy luzie wierzchołkowym sięgającym 3.6% rozpiętości łopatek. Do analizy zastosowano wizualizację śladów pozostawianych barwnikiem oraz teorię topologii, tj. struktur topologicznych reprezentujących powierzchnię łopatki oraz górnej i dolnej ściany krańcowej. Zaobserwowano, że w porównaniu do analogicznej palisady o zerowym kącie natarcia wszystkie punkty siodłowe przesuwają się w gorę przepływu, a obszar oderwania strugi rozszerza się wzdłuż promienia łopatki. Jednocześnie granica oderwania górnego i dolnego wiru przemieszcza się ku środkowi łopatki, gdy kąt natarcia narasta od zera do 20◦. Przy tych granicznych wartościach kąta natarcia łopatki o dodatniej krzywiźnie profilu eliminują górny wir podczas przejścia. Ponadto okazało się, że liczba punktów osobliwych zmniejszyła się podobnie, jak osłabiła się interakcja pomiędzy wirami przejścia i wirami upływu. Stwierdzono, że wzmacnia to efekt blokowania upływu poprzecznym przepływem na krańcowej ścianie łopatki, co ostatecznie redukuje straty indukowane upływem.

Źródło:

Journal of Theoretical and Applied Mechanics; 2013, 51, 2; 363-373
1429-2955

Pojawia się w:

Journal of Theoretical and Applied Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 11.

Tytuł:

Measuring fan speed using the impeller tip pressure method
Pomiar prędkości obrotowej wentylatora metodą oznaczania ciśnienia na końcówce wirnika

Autorzy:

Li, Y. M.
Chen, K. Y.

Powiązania:

https://bibliotekanauki.pl/articles/348569.pdf

Data publikacji:

2012

Wydawca:

Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH

Tematy:

końcówka wirnika
ciśnienie na końcówce wirnika
zmiany ciśnienia
prędkość obrotowa wentylatora
impeller tip
tip-pressure
pressure pulsation
fan speed

Opis:

The accurate measurement of fan speed is impact in the fan performance test experiments. As there is some relationship between the impeller tip pressure pulse frequency and speed of the impeller, the paper proposed a new impeller tip speed measurement method through counter-rotating fan speed measurement studies. The use of pressure sensors, data acquisition cards and programming technologies to measure the speed of reading directly integrated into the previous fan performance automated test systems was also presented. This proves that this is an effective method by comparing the results of the field tests.
Aby wykonać dokładny pomiar prędkości obrotowej wiatraka należy przeprowadzić test jego osiągów. Ponieważ istnieje związek pomiędzy częstotliwością zmian ciśnienia na końcówce wirnika i prędkością obracania wirnika, w niniejszym artykule zaproponowano nową metodę pomiaru prędkości obrotowej końcówki wirnika poprzez badanie pomiaru prędkości obrotowej wentylatora przeciwbieżnego. Przedstawiono również zastosowanie czujników ciśnienia, kart rejestracji danych oraz technologii programistycznych do pomiaru prędkości wskazań zawartych w poprzednich systemach automatycznego testowania osiągów wentylatora. Porównanie wyników prób terenowych dowodzi skuteczności tej metody.

Źródło:

AGH Journal of Mining and Geoengineering; 2012, 36, 3; 209-215
1732-6702

Pojawia się w:

AGH Journal of Mining and Geoengineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 12.

Tytuł:

Analysis of residual strength of a helicopter tail boom

Autorzy:

Reymer, P.
Leski, A.

Powiązania:

https://bibliotekanauki.pl/articles/246055.pdf

Data publikacji:

2010

Wydawca:

Instytut Techniczny Wojsk Lotniczych

Tematy:

residual strength
tail boom
crack tip opening angle

Opis:

The aim of this work is to determine the residual strength of a Mi-24 helicopter's tail boom with a structural damage. The idea of this work has come from the fact that these helicopters are operated on a battlefleld and often suffer such damages. It may be crucial to make a quick estimation whether any particular damage can cause a critical failure to the whole structure. The scope of this work covers static loading of the structure during landing. The analysis has been based on a numerical model that makes use of the Finite Element Method. The model has been developed using reverse engineering techniques. Structural discontinuities have been modelled in characteristic sections where stress concentrations occur. Boundary conditions and loads applied have been chosen to simulate normal and hard landings. Two failure criteria have been chosen: one based on the Crack Tip Opening Angle (CTOA) method that enables very efficient verification, and the second concerning the tail boom tip dislocation, taken from the helicopter,s alignment manual. The specific load history has been designed to enable detection of tail boom tip dislocation due to plastic strain in the vicinity of damage tips after the hard landing.

Źródło:

Journal of KONES; 2010, 17, 1; 343-349
1231-4005
2354-0133

Pojawia się w:

Journal of KONES

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 13.

Tytuł:

Rotor blade vibration simulator of steam turbine with aliasing frequencies up to 25 Hz

Autorzy:

Piechowski, L.
Rządkowski, R.
Troka, P.
Piechowski, P.
Szczepanik, R.

Powiązania:

https://bibliotekanauki.pl/articles/175409.pdf

Data publikacji:

2016

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

tip-timing
rotor blade vibration
blade vibration simulator

Opis:

The tip-timing measurement of rotor blade vibration of a real turbine is very expensive. An electronic simulator of unshrouded steam turbine rotor blade vibrations for aliasing frequencies up to 25 Hz is presented in this paper. The results of the simulated blade vibrations were compared with ones carried out on a real steam turbine. The simulator can be also used to: calibrate the measurement channels, help in the designing and manufacturing new tip-timing systems, and check the reliability of other tip-timing systems.

Źródło:

Transactions of the Institute of Fluid-Flow Machinery; 2016, 134; 121-129
0079-3205

Pojawia się w:

Transactions of the Institute of Fluid-Flow Machinery

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 14.

Tytuł:

Effect of circumferential grooves casing treatment on tip leakage flow and loss in a transonic mixed-flow compressor

Autorzy:

Qiang, X. Q.
Zhu, M. M.
Teng, J. F.

Powiązania:

https://bibliotekanauki.pl/articles/279263.pdf

Data publikacji:

2013

Wydawca:

Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej

Tematy:

compressor
casing treatment
tip leakage
flow loss
numerical simulation

Opis:

A numerical simulation of a single stage transonic mixed-flow compressor is presented. The simulation is run with a multi-passage grid that models the 3D, viscous, steady and unsteady flow field. The effect of circumferential grooves casing treatment on the compressor overall performance, tip leakage flow and loss has been studied. The results show that the narrow operating range has been significantly broaden by the casing treatment grooves, while the mismatching between the rotor and stator still exists and becomes even worse. Detailed analysis indicates that the fluid from circumferential grooves is injected into the blade passage near the suction surface and re-energizes the leakage flow, which makes mainly contribution to manipulation of the tip leakage flow and stall margin improvement. Since the pressure difference across the blade tip section has a great impact on the effectiveness of circumferential grooves, the positions of shock wave and tip leakage flow as well as where the interaction takes place ought to be taken into account through the casing treatment design procedure.

Źródło:

Journal of Theoretical and Applied Mechanics; 2013, 51, 4; 903-913
1429-2955

Pojawia się w:

Journal of Theoretical and Applied Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 15.

Tytuł:

Tip leakage flows in turbines

Autorzy:

Lampart, P.

Powiązania:

https://bibliotekanauki.pl/articles/1955214.pdf

Data publikacji:

2006

Wydawca:

Politechnika Gdańska

Tematy:

axial flow turbine
shrouded/unshrouded blades
tip leakage
CFD

Opis:

Mechanisms of formation of the tir leakage over shrouded and unshrouded rotor blades are described in the paper. The loss diagrams for these two types of leakage in a wide range of cascade inlet and outlet flow angles are also plotted. They are obtained in a theoretical way from a model of stream mixing with the help of simplifying assumptions concerning the load of the rotor profile. Results of numerical investigations based on a 3D RANS solver FlowER are also presented in the paper. They extend on the effects of geometrical and flow parameters of the cascade (stage or stage group) on the development of flow losses in the leakage-dominated region as well as on the interaction of tip leakage flow with secondary flows. The tip clearance size, the level of flow turning in the cascade, incidence angle and the effect of relative motion of the blades and endwall are considered here in the case of unshrouded free-tip blades. In the case of shrouded rotor blades the tip leakage mass flow rate and its direction on the re-entry to the blade-to-blade passage. Since the tip leakage non-uniformities are hardly dissipated within the blade row where they originate, the interaction of the tip leakage with the flow in the downstream stator is considered. Same investigations also take into account the effect of relative motion of the stator and rotor blades.

Źródło:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2006, 10, 2; 139-175
1428-6394

Pojawia się w:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 16.

Tytuł:

Numerical analysis of the tip vortex in an air-conditioners propeller fan

Autorzy:

Wang, J.
Wu, K.

Powiązania:

https://bibliotekanauki.pl/articles/1955218.pdf

Data publikacji:

2006

Wydawca:

Politechnika Gdańska

Tematy:

tip vortex
internal flow field
propeller fan
numerical simulation

Opis:

A steady, incompressible, turbulent flow field inside a propeller fan used in an air conditioner has been analyzed numerically using the single-equation Spalart-Allmaras turbulence model. It has been found that the formation of tip vortex starts from the blade tip's suction side at about one third of the axial chord's length aft of the rotor's leading edge. It is due to the rolling-up of the intense shear layer flow between the main axial flow and the suck-in inward flow caused by the large pressure difference between the pressure and the suction sides. The tip vortex passes through the blade passage in a curve reversed towards the direction of the blade's rotation. Its trace is partial to the tangential direction as it goes into the aft part of the blade passage covered by the shroud and, simultaneously, its trace in the radial direction is turned from the outward direction to the inward direction. The operating flow rates have an important effect on the axial position of the tip vor-tex's trace, while its effect on the radial position is negligible. At law flow rates, the vortex disappears at a location closer to the leading edge. The effect of the shroud's width on the tip vortex's trajectory is notable. For a fan with a wide shroud, the trace of the tip vortex moves upstream with a smaller radial influence region than that of a fan with a narrower shroud.

Źródło:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2006, 10, 2; 101-112
1428-6394

Pojawia się w:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 17.

Tytuł:

Microstructural study of failure phenomena in WC 94%-Co 6% hard metal alloy tips of radial picks

Autorzy:

Nahak, S.
Chattopadhyaya, S.
Dewangan, S.
Hloch, S.
Krolczyk, G.
Legutko, S.

Powiązania:

https://bibliotekanauki.pl/articles/102813.pdf

Data publikacji:

2017

Wydawca:

Stowarzyszenie Inżynierów i Techników Mechaników Polskich

Tematy:

radial picks
WC-Co tip
FESEM
EDS
failure behaviour

Opis:

An excellent combination of hardness, strength, stiffness and high melting point has proved the WC-Co as an ideal material for tools that are used for metal cutting, coal mining, oil drilling, etc. The ongoing research in WC-Co is focussed on enhancing its wear resistant properties as much as possible. For the purpose, many attempts have been made to study the tribological behaviour of WC-Co for a long time. Researchers have used various grades of WC-Co in different working environments and accordingly they have characterized the wear phenomena involved there within. In this direction of research, the present paper makes an attempt to understand various wear behaviours in WC 94%-Co 6% hard metal alloy. WC-Co was used as a tip of the coal cutting tool named radial pick. Two radial picks have been taken for critical analysis through field emission scanning electron microscopy (FESEM) attached with energy dispersive X-ray spectroscopy (EDS). In this work, the failure behaviours in the tools have been divided into five categories: (1) Abrasion on individual grain; (2) Corrosion in carbide grains; (3) Fragmentation and removal of WC grains; (4) Pores in WC grains; and (5) Coal and rock embedding. The most possible reasons behind each failure phenomenon have been explained comprehensively with the help of high-resolution microscopic images. However, it is usually observed that, initially, the tool gets minor cracks due to sudden impact. These cracks provide a path to the rock and coal particles to get entrenched inside the microstructure of cemented carbide. Finally, the intermixed external elements degrade the binder content (i.e. cobalt) and the tool becomes useless.

Źródło:

Advances in Science and Technology. Research Journal; 2017, 11, 1; 36-47
2299-8624

Pojawia się w:

Advances in Science and Technology. Research Journal

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 18.

Tytuł:

Numerical analysis on the influence of the twisted blade on the aerodynamic performance of turbine

Autorzy:

Jin, J.
Wang, Z.
Cao, L.

Powiązania:

https://bibliotekanauki.pl/articles/258444.pdf

Data publikacji:

2016

Wydawca:

Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa

Tematy:

turbine
twisted blade
leakage vortex
pressure gradient
tip clearance

Opis:

With the gradual increase of the thermal power unit capacity, the inlet steam parameters and flow of the turbine also increase gradually, which causes considerable secondary flow loss. Therefore, studying the causes and distribution of secondary flow loss within the level is of great significance to effectively improve the stage internal efficiency of turbine. Take high-pressure stage moving blade of a turbine as the research object, and adopt the k-ωSST model, the SIMPLEC algorithm to numerically simulate the formation and development process of leakage vortex between the tip clearance of the positive bending twisted blade and its effect on the secondary flow of cascade passage. Results show that relative to the conventional twisted blade, the scope of influence of leakage vortex which the steam flow formed near the suction surface of positive bending twisted blade and the disturbance to passage mainstream become smaller, and the increase of tip clearance has weakened the „C” type pressure gradient of suction surface of the positive bending twisted blade, increased the thickness of the boundary layer at both ends of blades and the loss of the blade end.

Źródło:

Polish Maritime Research; 2016, S 1; 86-90
1233-2585

Pojawia się w:

Polish Maritime Research

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 19.

Tytuł:

Importance of explant size and origin for cryopreservation of Rosa pomifera “Karpatia” shoot tips by a droplet vitrification method

Autorzy:

Kwasniewska, E.
Dziedzic, E.
Pawlowska, B.

Powiązania:

https://bibliotekanauki.pl/articles/951284.pdf

Data publikacji:

2015

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

cryopreservation
Rosa pomifera
shoot tip
droplet vitrification
axenic culture

Źródło:

BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2015, 96, 1
0860-7796

Pojawia się w:

BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 20.

Tytuł:

Experimental Study on the Half Flat Tip Serrated Trailing Edge for Stand Fan

Autorzy:

Lee, Hsiao Mun
Lim, Kian Meng
Xie, Jinlong
Lee, Heow Pueh

Powiązania:

https://bibliotekanauki.pl/articles/177337.pdf

Data publikacji:

2020

Wydawca:

Polska Akademia Nauk. Czasopisma i Monografie PAN

Tematy:

trailing edge noise
half flat tip
serration
stand fan

Opis:

The effectiveness of half flat tip serrations on reducing fan blade trailing edge noise was investigated using experimental methods. The experiments were conducted at an anechoic chamber under different rotating fan speeds. Numerical simulations were performed to investigate the mass flow rate generated by the serrated fan and compared with that by the baseline fan. The experimental results showed that the overall amount of noise reduction decreased with the increasing of the distance away from the fan. It was found that the effectiveness of the serrations was not proportional with the rotating speed of the fan where it was most effective at 263 rpm and 2041 rpm with noise reductions about 3.1 dBA and 3.5 dBA, respectively. This phenomenon might be depended on how trailing edge vortex would interact with the serrations at different speeds of the fan. The reduction of mass flow rate reduced with the increasing of the rotating speed and the highest reduction was found at 263 rpm which was about 18% and this reduction was accompanied by overall noise reduction of 3.1 dBA.

Źródło:

Archives of Acoustics; 2020, 45, 2; 359-365
0137-5075

Pojawia się w:

Archives of Acoustics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 21.

Tytuł:

Probe radius correction methods - review and comparison of existing methods

Autorzy:

Rak, A.
Woźniak, A.

Powiązania:

https://bibliotekanauki.pl/articles/385250.pdf

Data publikacji:

2009

Wydawca:

Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów

Tematy:

coordinate measuring machine (CMM)
scanning probe
probe tip radius correction

Opis:

Scanning technology has been becoming more common then ever. Scanning offers new and effective possibilities of measurement. Nowadays planning, production and assembling without high accurate metrology is impossible. Measurement of small, curved elements became much easier with great development of mechanical components of measure machines, such as: guideways, transducers, bearings, servomechanisms. All this improvement made possible to collect with good accuracy points in high density. Algorithms, and computer software were greatly improved as well. Especially, many efforts were put on probe radius correction algorithms development. In this paper a review and a comparison of probe radius correction methods are shown.

Źródło:

Journal of Automation Mobile Robotics and Intelligent Systems; 2009, 3, 4; 169-171
1897-8649
2080-2145

Pojawia się w:

Journal of Automation Mobile Robotics and Intelligent Systems

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 22.

Tytuł:

Multiple spike stall cells in low speed axial compressor rotor blade row

Autorzy:

Taghavi-Zenouz, R
Abbasi, S.

Powiązania:

https://bibliotekanauki.pl/articles/279770.pdf

Data publikacji:

2015

Wydawca:

Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej

Tematy:

axial compressor
spike stall inception
tip leakage flow
frequency spectrum

Opis:

Inception and development of multiple stall cells of short length scales are numerically investigated in an axial compressor rotor blade row. The method of investigation is based on time accurate three-dimensional full annulus simulations. Time dependent flow structure results revealed that there are two criteria responsible for inception of a special kind of stall, introduced as spike stall in the literature. These criteria are defined as leading edge spillage and trailing edge backflow, which occur at specific mass flow rates near to stall conditions. The numerical results revealed that once the spike stall cells appear, they cover roughly two blade passages in the circumferential direction and cover about 25% of the blade height. By further revolution of the blade row, the number of cells tends to increase. For the present case study, the number of stall cells increased to three after 8.5 rotor revolutions from the moment of the initial spike stall occurrence. Even at this moment, both of the above mentioned criteria for the spike stall inception have been observed within the blades passages. These events caused the inlet relative flow angle to the blade rows, and therefore the flow incidence angle and consequent blockage to the main flow, to increase. The tip leakage flow frequency spectrum has been studied through surveying instantaneous static pressure signals imposed on pressure side of the blades and also on the casing walls. These latter results showed that any further revolving of the rotor blade row, exceeding 8.5 revolutions, causes the spike stall to disturb the flow structure significantly.

Źródło:

Journal of Theoretical and Applied Mechanics; 2015, 53, 1; 47-57
1429-2955

Pojawia się w:

Journal of Theoretical and Applied Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 23.

Tytuł:

Research on Changes in Microstructures and Mechanical Properties of Welding Caps as a Result of their Usage During Resistance Spot Welding Process

Autorzy:

Rdzawski, Zbigniew
Kwaśniewski, Paweł
Głuchowski, Wojciech
Łagoda, Marek
Maleta, Marcin
Boczkal, Sonia
Franczak, Krystian

Powiązania:

https://bibliotekanauki.pl/articles/2203749.pdf

Data publikacji:

2023

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

CuCrZr alloy
resistance spot welding
mechanical properties
microanalysis
tip electrodes

Opis:

Mating electrodes made of copper alloys are commonly used for welding galvanized steel sheets used in the production of car bodies. These alloys are characterized by high mechanical properties, a high level of electrical and thermal conductivity as well as the stability of these properties under changing conditions of current, thermal and mechanical load. Much careful attention was paid to the essence of the ongoing structural changes as well as to the mechanical properties in the welding process (RSW - Resistant Spot Welding) of steel sheets, including high-strength ones. There is a lack of research on structural changes and the related mechanical properties occurring in welding electrodes made of copper alloys caused by the welding process. This study is devoted to these issues and contains a critical review of the research results enabling a better understanding of the relationships between the structure and properties of welding electrodes caused by the cyclic welding process. In order to illustrate the phenomena occurring during the welding process, both in the material to be welded and in the tip electrodes, hardness and structural tests were carried out on electrode samples before and after their exploitation. The data collected in the article supplements a certain lack of information in the literature regarding the microstructural aspects of the welding process of galvanized steel sheets for the production of car bodies. The conducted research may be the starting point for the search for more effective materials for the tip electrodes.

Źródło:

Archives of Metallurgy and Materials; 2023, 68, 1; 295--306
1733-3490

Pojawia się w:

Archives of Metallurgy and Materials

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 24.

Tytuł:

Effects of boundary layer control method on hydrodynamic characteristics and tip vortex creation of a hydrofoil

Autorzy:

Ghadimi, P.
Araz-Tanha, A.
Nemati-Kourabbasloo, N.
Tavakoli, S.

Powiązania:

https://bibliotekanauki.pl/articles/259965.pdf

Data publikacji:

2017

Wydawca:

Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa

Tematy:

steady water injection
boundary layer control
hydrofoil
NACA 0015
tip vortex

Opis:

There is currently a significant focus on using boundary layer control (BLC) approach for controlling the flow around bodies, especially the foil sections. In marine engineering this is done with the hope of increasing the lift – to – drag ratio and efficiency of the hydrofoils. In this paper, effects of the method on hydrodynamic characteristics and tip vortex formation of a hydrofoil are studied. Steady water injection at the tip of the hydrofoil is simulated in different conditions by using ANSYS-CFX commercial software. Validity of the proposed simulations is verified by comparing the obtained results against available experimental data. Effects of the injection on the lift, drag, and lift – to – drag ratio are studied and the ranges within which the injection has the most positive or negative effects, are determined. Furthermore, flow pattern and pressure variation are studied upon the water injection to determine the most positive and negative case and to ascertain the main reasons triggering these phenomena.

Źródło:

Polish Maritime Research; 2017, 2; 27-39
1233-2585

Pojawia się w:

Polish Maritime Research

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 25.

Tytuł:

A simple model of the scanning near-field optical microscopy probe tip for electric field enhancement

Autorzy:

Wang, Y.
Cai, W.
Yang, M.
Liu, Z.
Shang, G.

Powiązania:

https://bibliotekanauki.pl/articles/174091.pdf

Data publikacji:

2017

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

near-field tip
electromagnetic field enhancement
finite-difference time-domain
FDTD

Opis:

In this paper, we present a simple near-field probe model that is composed of an elongated ellipsoid and a finite metal truncated cone. The elongated ellipsoid has been shown to act as a protrusion or separate particle near a truncated cone apex with strong near-field enhancement under laser excitation. By controllably varying the length of the ellipsoid protrusion from the truncated cone, the truncated cone-ellipsoid probes can be adapted to the suitability of near-field probes. The effects of substrate material and excitation wavelength on the near field enhancement for different tip apexes are also discussed. In addition, we compared the properties of the truncated cone-ellipsoid probe with the widely used hemisphere conical tip by launching surface plasmon polaritons on plasmonic waveguides to prove the suitability of the truncated cone-ellipsoid probes as high performance near-field probes. The present simple model would provide a theoretical basis for the actual construction of probes.

Źródło:

Optica Applicata; 2017, 47, 1; 119-130
0078-5466
1899-7015

Pojawia się w:

Optica Applicata

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 26.

Tytuł:

In vitro regeneration of Plantago media L. from shoot tips and other seedling explants

Autorzy:

Budzianowska, A.
Malkiewicz, M.
Budzianowski, J.

Powiązania:

https://bibliotekanauki.pl/articles/951282.pdf

Data publikacji:

2015

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

conference
Plantago media
in vitro
regeneration
shoot tip
seedling explant
propagation

Źródło:

BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2015, 96, 1
0860-7796

Pojawia się w:

BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 27.

Tytuł:

In vitro regeneration of Centaurium erythraea Rafn from shoot tips and other seedling explants

Autorzy:

Piatczak, E
Wysokinska, H.

Powiązania:

https://bibliotekanauki.pl/articles/56437.pdf

Data publikacji:

2003

Wydawca:

Polskie Towarzystwo Botaniczne

Tematy:

Centaurium erythraea
micropropagation
seedling explant
shoot tip
regeneration
organogenesis
in vitro
Gentianaceae

Opis:

Various explants from 30-day-old seedlings of Centaurium erythraea Rafn were evaluated for their morphogenetic capacity under in vitro culture conditions. Shoot formation from shoot tip explants was achieved mainly through adventitious bud differentiation. The highest number of shoots (up to 43.3 ± 2.2 from a single shoot tip) was obtained on Murashige and Skoog medium (MS) supplemented with indole-3-acetic acid (IAA) (0.57 μM) and 6-benzylaminopurine (BAP) (4.4 μM). Adventitious shoot regeneration was also achieved through organogenesis from calluses obtained from hypocotyls, cotyledons, roots and leaves on MS medium containing IAA (2.85 μM) and BAP (0.88 μM). Significant differences were noted between explant types in their effects on shoot regeneration. In the primary culture, the best response was obtained either from calluses derived from roots or leaves (44.4 ± 4.5 and 40.2 ± 6.0 shoots per callus, respectively). The number of subcultures of inoculated calluses affected both the multiplication rate (the number of shoots/explant) and shoot morphology (the frequency of shoot hyperhydricity). Shoots rooted with the frequency of 94-100% after culture on MS medium without growth regulators. Plantlets were successfully acclimatized (97%) under high relative humidity and then moved to the greenhouse.

Źródło:

Acta Societatis Botanicorum Poloniae; 2003, 72, 4
0001-6977
2083-9480

Pojawia się w:

Acta Societatis Botanicorum Poloniae

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 28.

Tytuł:

Multiscale water drop contact angles at selected silica surfaces

Autorzy:

Zhang, Chen
Wang, Xuming
Li, Lixia
Jin, Jiaqi
Polson, Randy
Miller, Jan D.

Powiązania:

https://bibliotekanauki.pl/articles/2146924.pdf

Data publikacji:

2022

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

contact angle
atomic force microscopy
hollow tip
submicron-drop
wettability
MD simulation

Opis:

In this study, multiscale advancing contact angles for glycerol/water drops at silica surfaces are reported for millidrops, submicron-drops, and nanodrops. Selected silica surfaces were muscovite, silicon, and talc. The contact angles for millidrops (1–2 mm) were determined by the traditional sessile drop technique. For submicron-drops (0.1–1.0 μm), a hollow tip Atomic Force Microscope (AFM) procedure was used. The contact angles for nanodrops (~7 nm) were examined from Molecular Dynamics (MD) simulation. The results were compared to evaluate the effect of drop size on the contact angle. In the case of the hydrophobic talc surface, the 75° advancing contact angle did not vary significantly with drop size. For the hydrophilic muscovite surface, the water drop wet the surface and an advancing contact angle of about 10° was found for the millidrops and submicron-drops. However, for the MD simulated nanodrops, attachment and spreading of the ~7 nm drop created a 2D film of molecular dimensions, the contact angle of which was difficult to define and varied from 0° to 17°. Perhaps of equal interest from the MD simulation results was that the spreading of the glycerol/water nanodrop at the muscovite surface resulted in crystallographic directional transport of water molecules to the extremities of the 2D film. Such separation and segregation left the center of the film with an increased concentration of glycerol. Based on these results, the line tension, which has been found in other investigations to account for contact angle decrease with a decrease in drop size, does not seem to be a significant factor in this study.

Źródło:

Physicochemical Problems of Mineral Processing; 2022, 58, 5; art. no. 152154
1643-1049
2084-4735

Pojawia się w:

Physicochemical Problems of Mineral Processing

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 29.

Tytuł:

Verification of strength resistance of sandy soil using small scale penetrometer tests

Autorzy:

Saleem, Hiba D.
Aldefae, Asad H.
Humaish, Wissam H.

Powiązania:

https://bibliotekanauki.pl/articles/35538646.pdf

Data publikacji:

2021

Wydawca:

Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie

Tematy:

cone penetration
tip resistance
sleeve resistance
relative density
angle of internal friction

Opis:

This study focuses on utilizing cone penetrometer models to determine strength (resistance) of sandy soil and also assessment how the relative density and the angle of friction effects on the measured cone penetration resistance in sandy soil. Simple empirical equations are used also to determine the cone penetration resistance components such as the sleeve resistance and the tip resistance. Simple comparison is performed between the measured and calculated soil strength and well agreement is noticed between them.

Źródło:

Scientific Review Engineering and Environmental Sciences; 2021, 30, 2; 304-314
1732-9353

Pojawia się w:

Scientific Review Engineering and Environmental Sciences

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 30.

Tytuł:

Numerical simulation and theoretical analysis of the 3D viscous flow in centrifugal impellers

Autorzy:

Kang, S.
Hirsch, Ch.

Powiązania:

https://bibliotekanauki.pl/articles/1967654.pdf

Data publikacji:

2001

Wydawca:

Politechnika Gdańska

Tematy:

centrifugal compressor
secondary flow
CFD
computational fluid dynamics CFD
tip leakage flows

Opis:

This paper investigates the three-dimensional viscous ow in centrifugal impellers through theoretical analysis and numerical simulations, which is a summary of the authors' recent work. A quantitative evaluation of the dierent contributions to the streamwise vorticity is performed, namely, the passage vortices along the endwalls due to the ow turning; a passage vortex generated by the Coriolis forces proportional to the local loading and mainly active in the radial parts of the impeller; blade surface vortices due to the meridional curvature. In the numerical simulation the NASA Large Scale Centrifugal Compressor (LSCC) impeller with vaneless diuser is computed at three ow rates. An advanced Navier-Stokes solver, EURANUS/TURBO is applied with an algebraic turbulence model of Badwin-Lomax and a linear k-" model for closure, for dierent meshes. An in-depth validation has been performed based on the measured data. An excellent agreement is obtained for most of the data over a wide region of the ow passage. Structures of the 3D ow in the blade passage and the tip region, and their variations with ow rate as well, are analysed based on the numerical results.

Źródło:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2001, 5, 4; 433-458
1428-6394

Pojawia się w:

TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 31.

Tytuł:

Application of micronucleus assay in plants to monitor environmental pollution in situ

Autorzy:

Kośmider, Beata
Osiecka, Regina
Siciński, Jan T

Powiązania:

https://bibliotekanauki.pl/articles/764964.pdf

Data publikacji:

2008

Wydawca:

Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego

Tematy:

monitoring in situ
environmental pollution
micronuclei
pollen mother cells
root tip cells

Opis:

Samples of 5 vascular plant species: Achillea millefolium L., Artemisia vulgaris L., Festuca gigantea (L.) VILL., Ranunculus acris L. s. str. and Vicia angustifolia L. were collected near Fuel Storage Station, Chemical Fibre Factory “Wistom” in Tomaszów Mazowiecki and Sewage Treatment Plant in Sulejów. Genotoxicity of environmental pollution was analysed using micronucleus assays in pollen mother and root tip cells in comparison with plant material collected in the Tatra and Babia G óra National Parks. Abnorm alities in morphology of plants growing in polluted areas were also found. The cytogenetical analyses revealed positive correlation between the percentage of micronuclei and the presence of heavy metals in soil. Pollen mother cells (germ line) were found more susceptible to DNA damage as compared with root tip cells (somatic line).

Źródło:

Acta Universitatis Lodziensis. Folia Biologica et Oecologica; 2008, 4
1730-2366
2083-8484

Pojawia się w:

Acta Universitatis Lodziensis. Folia Biologica et Oecologica

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 32.

Tytuł:

Insight Into Vibration Sources in Turbines

Autorzy:

Moneta, Grzegorz
Jachimowicz, Jerzy
Pietrzakowski, Marek
Doligalski, Adam
Szwedowicz, Jarosław

Powiązania:

https://bibliotekanauki.pl/articles/2105187.pdf

Data publikacji:

2021

Wydawca:

Sieć Badawcza Łukasiewicz - Instytut Lotnictwa

Tematy:

vibrations
blade
gas turbine
turbine engine
strain gauge
tip timing
Additive Manufacturing

Opis:

Despite of nearly 100 years of turbine engine development and design, blade vibrations remain a great engineering challenge. The rotating turbine blades’ vibrations lead to cyclic oscillations, which result in alternating stress and strain in harsh environments of high temperature and pressure. In modern aeroengines, high hot flow velocities might generate erosion and corrosion pitting on the metal surfaces, that leverage remarkably mean stresses. The combination of both mean and alternating stresses can lead to unexpected engine failures, especially under resonance conditions. Then, alternating stress amplitudes can exceed the safety endurance limit, what accelerates the high cyclic fatigue leading quickly to catastrophic failure of the blade. Concerning the existing state-of-the-art and new market demands, this paper revises forced vibrations with respect to excitation mechanisms related to three design levels: (i) a component like the blade design, (ii) turbine stage design consisting of vanes and blades and (iii) a system design of a combustor and turbine. This work reviews the best practices for preventing the crotating turbine and compressor blades from High Cyclic Fatigue in the design process. Finally, an engine commissioning is briefly weighed up all the pros and cons to the experimental validations and needed measuring equipment.

Źródło:

Fatigue of Aircraft Structures; 2021, 13; 40--53
2081-7738
2300-7591

Pojawia się w:

Fatigue of Aircraft Structures

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 33.

Tytuł:

Evolutionary computing approaches to optimum design of fuzzy logic controller for a flexible robot system

Autorzy:

Subudhi, B.
Ranasingh, S.

Powiązania:

https://bibliotekanauki.pl/articles/230107.pdf

Data publikacji:

2013

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

flexible manipulator
fuzzy logic
genetic algorithm
bacteria foraging optimization
tip position tracking

Opis:

This paper presents the design of a Fuzzy Logic Controller (FLC) whose parameters are optimized by using Genetic Algorithm (GA) and Bacteria Foraging Optimization (BFO) for tip position control of a single link flexible manipulator. The proposed FLC is designed by minimizing the fitness function, which is defined as a function of tip position error, through GA and BFO optimization algorithms achieving perfect tip position tracking of the single link flexible manipulator. Then the tip position responses obtained by using both the above controllers are compared to suggest the best controller for the tip position tracking.

Źródło:

Archives of Control Sciences; 2013, 23, 4; 395-412
1230-2384

Pojawia się w:

Archives of Control Sciences

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 34.

Tytuł:

Numerical loss analysis on slot-type casing treatment in a transonic compressor stage

Autorzy:

Zhu, M.-M.
Qiang, X.-Q.
Teng, J.-F.

Powiązania:

https://bibliotekanauki.pl/articles/280437.pdf

Data publikacji:

2017

Wydawca:

Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej

Tematy:

axial compressor
numerical simulation
slot-type casing treatment
loss mechanism
tip leakage flow

Opis:

To understand the loss mechanism of slot-type casing treatment, a numerical loss analysis has been carried out in a 1.5 axial transonic compressor stage with various slots. Spanwise and streamwise distribution curves of pitch-averaged entropy have been presented to survey the development of loss generation. Further, detailed entropy distributions at eight axial cuts, which have been taken through the blade row and slots, have been further analyzed to interpret the loss mechanism. The most dramatic loss growth occurred above 95% span, which directly resulted from slots injection flow upstream the leading edge. Loss generations with smooth casing have been primarily ascribed to low-momentum tip leakage flow/vortex and suction surface separation at the leading edge. CU0 slot, the arc-curved slots with 50% rotor tip exposure, has been capable of suppressing the suction surface separation loss. Meanwhile, accelerated tip leakage flow brought about additional loss near the casing and pressure surface. Upstream high entropy flow would be absorbed into the rear portion of slots repeatedly, which resulted in further loss.

Źródło:

Journal of Theoretical and Applied Mechanics; 2017, 55, 1; 293-306
1429-2955

Pojawia się w:

Journal of Theoretical and Applied Mechanics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 35.

Tytuł:

Design and evaluation of a needle tip measurement system based on binocular vision

Autorzy:

Lin, Yuyang
Shi, Yunlai
Zhang, Jun
Wang, Fugang
Sun, Haichao

Powiązania:

https://bibliotekanauki.pl/articles/220501.pdf

Data publikacji:

2020

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

needle tip measurement
binocular vision system
measurement capability analysis
non-contact optical positioning

Opis:

The precise location of the needle tip is critical in robot-assisted needle-based percutaneous interventions. An automatic needle tip measuring system based on binocular vision technology with the advantages of non-contact, excellent accuracy and high stability is designed and evaluated. First the measurement requirements of the prostate intervention robot are introduced. A laser interferometer is used as the reference for measuring the position of the needle tip whose relative position variation is described as the needle tip distance in the time domain. The parameters of the binocular cameras are obtained by Zhang’s calibration method. Then a robust needle tip extraction algorithm is specially designed to detect the pixel coordinates of the needle tip without installing the marked points. Once the binocular cameras have completed the stereo matching, the 3D coordinates of the needle tip are estimated. The measurement capability analysis (MCA) is used to evaluate the performance of the proposed system. The accuracy of the system can be controlled within 0.3621 mm. The agreement analysis is conducted by the Bland-Altman analysis, and the Pearson correlation coefficient is 0.999847. The P/T ratio value is 16.42% in the repeatability analysis. The results indicate that the accuracy and stability of the binocular vision needle tip measuring system are adequate to meet the requirement for the needle tip measurement in percutaneous interventions.

Źródło:

Metrology and Measurement Systems; 2020, 27, 3; 495-512
0860-8229

Pojawia się w:

Metrology and Measurement Systems

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 36.

Tytuł:

Analiza wpływu ciśnienia wtrysku w układzie common rail na zasięg strugi wybranych paliw zastępczych
Analysis of the influence of injection pressure in common rail system on spray tip penetration of the selected alternative fuels

Autorzy:

Jaworski, A.
Kuszewski, H.
Lejda, K.
Ustrzycki, A.
Woś, P.

Powiązania:

https://bibliotekanauki.pl/articles/133329.pdf

Data publikacji:

2013

Wydawca:

Polskie Towarzystwo Naukowe Silników Spalinowych

Tematy:

wtrysk paliwa
paliwa alternatywne
zasięg strugi
fuel injection
alternative fuels
spray tip penetration

Opis:

W artykule przedstawiono badania wpływu ciśnienia wtrysku na zasięg strugi paliwa dla wybranych paliw takich jak olej napędowy, biodiesel, olej rzepakowy oraz ich mieszaniny. Badania realizowano na specjalnie opracowanym stanowisku z układem zasilania typu Common Rail, przy wtrysku do komory wypełnionej badanym paliwem. Badania prowadzono dla różnych ciśnień w zasobniku, a do wyznaczenia zasięgu strugi użyto systemu VisioScope firmy AVL. Zasięg strugi określano na podstawie zarejestrowanych przebiegów w funkcji kąta obrotu wałka pompy wysokiego ciśnienia.
This article presents the research results of influence of injection pressure on the spray tip penetration of selected fuels such as diesel, biodiesel, rapeseed oil and mixtures of these fuels. The study was performed on a specially developed test stand with a Common Rail injection system, and at fuel injected into the chamber filled with research fuel. The study was made for a different pressures in the rail; for determination of spray tip penetration the AVL VisioScope system was used. The results was determined on the base of recorded pictures of injected fuel stream as a function of rotation angle of the high pressure pump shaft.

Źródło:

Combustion Engines; 2013, 52, 3; 618-624
2300-9896
2658-1442

Pojawia się w:

Combustion Engines

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 37.

Tytuł:

Magnet loss analysis for a high-speed PM machine with segmented PM and modified tooth-tips shape

Autorzy:

Mlot, A.
Łukaniszyn, M.
Korkosz, M.

Powiązania:

https://bibliotekanauki.pl/articles/140982.pdf

Data publikacji:

2016

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

magnet loss reduction
magnet segmentation
tooth-tip modification
permanent magnet machine
high-speed motor

Opis:

This paper presents the loss-oriented performance analysis of a radial highspeed permanent magnet (PM) machine with concentrated windings for automotive application. The PM synchronous machine was designed for an operating frequency up to 800 Hz. The main aim of this paper is to analyse the selected methods for magnet eddycurrent loss reduction. The first approach to rotor modification regards magnet segmentation in circumferential and axial directions. The second approach is based on changes in tooth-tips shape of the stator. The best variants of tooth-tip shapes are determined for further investigation, and adopted with a rotor having magnet segmentation. It is found that the machine with a segmented magnet leads to magnet loss reduction by 81%. Further loss reduction by 45% can be realized with the proposed tooth-tip shape. Additionally, owing to the stator and rotor modifications, the main machine parameters are investigated, such as back-EMF, electromagnetic torque, torque ripple and cogging torque. The 2-D and 3-D finite element analysis (FEA) is used for electromagnetic analysis. An experimental approach based on a partially wound stator is employed to verify the 3-D FEA.

Źródło:

Archives of Electrical Engineering; 2016, 65, 4; 671-683
1427-4221
2300-2506

Pojawia się w:

Archives of Electrical Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 38.

Tytuł:

Study of Effect of Linear Tip Relief Modification in Power Transmission Efficiency of Spur Gears

Autorzy:

Thamba, Narendiranath Babu
Tambare, Abhijeet Mukund
Ananthanarayanan, Krishna Caitanya
Duraiswamy, Rama Prabha
Thangavelu, Shankar
Easwara Pillai, Raj Kumar
Mangalaraja, Ramalinga Viswanathan

Powiązania:

https://bibliotekanauki.pl/articles/176575.pdf

Data publikacji:

2020

Wydawca:

Polska Akademia Nauk. Czasopisma i Monografie PAN

Tematy:

linear gear tip relief profile modification
tooth profile deformation
transmission efficiency
TE
transmission error

Opis:

This paper explores the influence of linear gear tip relief modification on power transmission efficiency. In real time applications gears experience transmission error (TE) during operation which increases noise and vibration and also results in increased tooth profile deformation during operation of the gear. By providing tip relief profile modification this TE can be decreased. Using MATLAB for computation and ANSYS for the simulation of deformation, stress, strain, life, and factor of safety results for the gear assemblies are obtained. Deformation results are used for the computation change in power transmission efficiency followed by the modal and harmonic analysis of the gears and gear assemblies to determine change in the first mode of natural frequency.

Źródło:

Archives of Acoustics; 2020, 45, 2; 271-282
0137-5075

Pojawia się w:

Archives of Acoustics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 39.

Tytuł:

Cytogenetic effects of Fusarium mycotoxins on root tip cells of rye [Secale cereale L.], wheat [Triticum aestivum L.] and field bean [Vicia faba L.var.minor]

Autorzy:

Packa, D

Powiązania:

https://bibliotekanauki.pl/articles/2046676.pdf

Data publikacji:

1997

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

mycotoxin
rye
rot tip
fumonisin B1
fumonisin B3
mitosis
Triticum aestivum
fungi
tip cell
Fusarium
chromosome
wheat
Secale cereale
bean
fumonisin B2
Vicia faba var.minor
plant tissue
metaphase
moniliformin

Opis:

The effects of fusarial toxins: DAS, T-2, DON, 3 Ac-DON, MON and ZEA, on actively dividing root tip cells of rye, wheat and field bean were investigated. Three concentrations: 1, 5 and 10 µg mL⁻¹ were applied for 24 hours. Nuclei and chromosomes were stained using the Feulgens method. It has been found that trichothecene mycotoxins (DAS, T-2, DON, 3 Ac-DON) had a profound effect on mitosis, as they decreased the mitotic index, produced excessive condensation of pro- and metaphase chromosomes, C-metaphascs and C-anaphases, and caused an accumulation of metaphases. The main effect of trichothecene mycotoxins, probably caused via their influence on protein synthesis, was abnormal functioning of the mitotic spindle.

Źródło:

Journal of Applied Genetics; 1997, 38, 3; 259-272
1234-1983

Pojawia się w:

Journal of Applied Genetics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 40.

Tytuł:

Micropropagation of Plantago asiatica L. through culture of shoot-tips

Autorzy:

Makowczynska, J
Andrzejewska-Golec, E.

Powiązania:

https://bibliotekanauki.pl/articles/58965.pdf

Data publikacji:

2003

Wydawca:

Polskie Towarzystwo Botaniczne

Tematy:

shoot tip culture
rooting
micropropagation
medicinal plant
Plantago asiatica
Plantaginaceae
in vitro
medicinal species

Opis:

Shoot-tip multiplication of the medicinal species - Plantago asiatica was carried on MS medium with IAA and BAP or kinetin. Best results in micropropagation were achieved by adding 0.1 mg/dm3 IAA and 1 mg/dm3 BAP. After 6 weeks shoots were transferred to MS medium for rooting. The resulting plantlets were transferred after 8 weeks into pots and after a period of adaptation into the ground (field culture). The species Plantago asiatica was propagated in vitro by shoot-tip multiplication for the first time.

Źródło:

Acta Societatis Botanicorum Poloniae; 2003, 72, 3
0001-6977
2083-9480

Pojawia się w:

Acta Societatis Botanicorum Poloniae

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 41.

Tytuł:

Molecular dynamics simulation of an aqueous Na2SO4 solution

Autorzy:

Nieszporek, Krzysztof
Nieszporek, Jolanta

Powiązania:

https://bibliotekanauki.pl/articles/764099.pdf

Data publikacji:

2017

Wydawca:

Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej

Tematy:

hydrogen bond
sulfate
water
solvation structure
tip3p
radial distribution function
hydration shell

Opis:

The structure of sodium sulfate in tip3p water solution with the concentration of 0.1191 mol/dm3 was studied by means of classical molecular dynamics. Both ions have clear hydration shells. The comparison between radial distribution functions and cumulative numbers of selected atoms around the reference one makes it possible to precisely describe the structure of investigated system. Applying such tools geometrical parameters of the hydrogen bond of the dimer SO42-/H2O have been obtained. 

Źródło:

Annales Universitatis Mariae Curie-Skłodowska, sectio AA – Chemia; 2017, 72, 2
2083-358X

Pojawia się w:

Annales Universitatis Mariae Curie-Skłodowska, sectio AA – Chemia

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 42.

Tytuł:

A protocol for synthetic seeds from Salvia officinalis L. shoot tips

Autorzy:

Grzegorczyk, I.
Wysokinska, H.

Powiązania:

https://bibliotekanauki.pl/articles/19244.pdf

Data publikacji:

2011

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

synthetic seed
seed
Salvia officinalis
shoot tip
calcium alginate
cold storage
encapsulation
sage
perennial plant

Opis:

Shoot tips excised from shoot culture of Salvia officinalis were encapsulated in 2% or 3% (w/v) sodium alginate and exposed to 50 mM calcium chloride for complexation. Immediately or after 6, 12 or 24 weeks of storage at 4°C, the synthetic seeds were cultured for 6 weeks on half-strength MS medium supplemented with indole-3- acetic acid (IAA) (0.1 mg/l) and solidified with 0.7% agar. The frequency of shoot and root emergence from encapsulated shoot tips was affected by the concentrations of sodium alginate and additives in the gel matrix (sucrose, gibberellic acid, MS nutrient medium) as well as duration of storage. The frequency of shoot and root induction of non-stored synthetic seeds was highest with shoot tips encapsulated with 2% sodium alginate containing 1.5% sucrose and 0.5 mg/l gibberellic acid (GA3). Shoot tips maintained their viability and ability to develop shoots even after 24 weeks of storage when they were encapsulated in 3% alginate with 1/3 MS medium, sucrose (1.5%) and GA3 (0.25 mg/l). Root formation tended to decrease with storage time. Overall, 90% of the plantlets derived from stored and non-stored synthetic seeds survived in the greenhouse and grew to phenotypically normal plants. This procedure can enable the use of synthetic seed technology for germplasm conservation of S. officinalis, a plant species of high medical and commercial value.

Źródło:

Acta Biologica Cracoviensia. Series Botanica; 2011, 53, 1
0001-5296

Pojawia się w:

Acta Biologica Cracoviensia. Series Botanica

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 43.

Tytuł:

Heavy Metals in Soil and Plants During Revegetation of Coal Mine Spoil Tips and Surrounded Territories

Autorzy:

Kucher, Larisa
Krasnoshtan, Igor
Nedilska, Uliana
Muliarchuk, Oksana
Manzii, Olena
Menderetsky, Vadim
Boroday, Vira
Beregniak, Evgeniy
Voitsekhivskyi, Volodymyr
Myronycheva, Olena

Powiązania:

https://bibliotekanauki.pl/articles/27323823.pdf

Data publikacji:

2023

Wydawca:

Polskie Towarzystwo Inżynierii Ekologicznej

Tematy:

spoil tip
rock waste
heavy metals
threshold limiting value
soil
pH
ordinary chernozem
plant biomass

Opis:

Coal mining in Donbas is a global problem as it causes the destabilization of ecological landscapes. Spoil tips, covering almost 52% of the territory, alter the topography of the land, affect the ecosystem, and decrease soil fertility. The soils become degraded and are unsuitable for agricultural use. The occupation of the Donetsk region by the Russian Federation has suspended the observation and research of man-made influence on this territory, which is a major concern for the scientific community. To reduce the negative impact of spoil tips, it is necessary to slow down the process of pyrite oxidation and the formation of toxic substances, as well as the migration of heavy metals due to erosion. Biological reclamation with grass and woody plants can help in achieving this goal. Another urgent issue is the constant supervision and assessment of the suitability of the bedrock of coal mines for agricultural use. The study investigated the total and mobile content of heavy metals in the rock samples from the “South Donbaska-1” mine, ordinary chernozem (background soil), and vegetation growing on the spoil tip. The results showed that the content of Co, Cr, Cu, and Fe in the rock of the spoil tip is higher than in the background soils. The content of heavy metals gradually decreases as the distance from the spoil tip increases. The content of Pb in ordinary chernozem and rock is practically the same, indicating its active migration. An analysis of the biomass of plant samples growing on the spoil tip showed that the content of Co, Cu, and Zn was within the limits of the threshold limiting values. However, the content of other studied elements exceeded the permissible norms. The research results provide information on the ecological state of the spoil tip and can be used for recreational as well as reclamation works in these areas.

Źródło:

Journal of Ecological Engineering; 2023, 24, 7; 234--245
2299-8993

Pojawia się w:

Journal of Ecological Engineering

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 44.

Tytuł:

Zastosowanie metody inwersji danych z pomiarów elektrooporowych do oceny stanu termicznego hałdy pogórniczej w Chorzowie
The use of the electrical resistivity data inversion method for thermal state assessment of a coal mine heap in Chorzów

Autorzy:

Kotyrba, A.
Siwek, A.

Powiązania:

https://bibliotekanauki.pl/articles/2075670.pdf

Data publikacji:

2017

Wydawca:

Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy

Tematy:

Górny Śląsk
węgiel
odpady
składowisko
geotermia
elektrooporowość
Upper Silesia
coal
waste
spoil tip
geothermics
geoelectrics

Opis:

Air conditions in post-mining areas are threatened by thermal activity of old spoil tips of coal mines. Reclamation operations cause only time-limited suppression of the oxidation process of carbon particles in the spoil heap. There are different reasons for that process. One of them is the incorrectly recognized geometry of the combustion spots in the spoil tip mass and the ways in which they are powered by oxygen from the atmosphere. The 1D inversion of vertical resistivity sounding data (VES) allows visualizing the down-going thermal effects and concluding about transport of atmospheric air (oxygen) and combustion gases in the whole mass. The resistivity distribution within waste can effectively support interpretation of geochemical and geothermic observations made on the spoil tip. The article describes the results of resistivity measurements made on an old spoil tip with waste from coal production in a heavy urbanized area of Chorzów City. Currently, the area of the former spoil heap is used for recreation and sports purposes (a park).

Źródło:

Przegląd Geologiczny; 2017, 65, 8; 496--504
0033-2151

Pojawia się w:

Przegląd Geologiczny

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 45.

Tytuł:

Cryopreservation of cherry rootstock Gisela 5 (Prunus cerasus × Prunus canescens) shoot tips by droplet-vitrification technique

Autorzy:

Ruzic, D.
Vujovic, T.
Cerovic, R.

Powiązania:

https://bibliotekanauki.pl/articles/2189.pdf

Data publikacji:

2013

Wydawca:

Instytut Ogrodnictwa

Tematy:

cherry
Gisela 5 cultivar
rootstock
cryopreservation
Prunus cerasus × Prunus canescens
droplet-vitrification technique
shoot tip

Źródło:

Journal of Horticultural Research; 2013, 21, 2
2300-5009

Pojawia się w:

Journal of Horticultural Research

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 46.

Tytuł:

Spatial, functional and comparative analysis of a Late Palaeolithic Swiderian culture settlement at Kraków-Bieżanów site 15
Przestrzenna, funkcjonalna i porównawcza analiza obozowiska kultury świderskiej z Krakowa Bieżanowa stanowisko 15

Autorzy:

Pyżewicz, Katarzyna
Serwatka, Kamil
Stefański, Damian

Powiązania:

https://bibliotekanauki.pl/articles/584876.pdf

Data publikacji:

2017

Wydawca:

Łódzkie Towarzystwo Naukowe

Tematy:

Paleolit schyłkowy
kultura świderska
analiza geometryczno-mrfometryczna kształtu
analiza traseologiczna
analiza przekroju poprzecznego
Late Palaeolithic
Swiderian culture
Swiderian point
use-wear analysis
tip cross-sectional area analysis
tip angle analysis
geometric-morphometric outline shape analysis

Opis:

Niniejszy artykuł jest studium poświęconym organizacji przestrzennej osadnictwa kultury świderskiej na stanowisku w Krakowie-Bieżanowie 15. W trakcie szerokopłaszczyznowych badań ratowniczych (2004-2008), pozyskano tam liczne materiały krzemienne wiązane z tą kulturą. Pochodzą one zarówno z obiektów, jak np. niewielkiej krzemienicy (KB-15/1 – obiekt 1), czy skupiska materiału (obiekt 2 i 3), jak również ze znacznej części przebadanej partii stanowiska, gdzie zostały podjęte jako znaleziska pojedyncze. Analiza planigraficzna podstawowych grup narzędziowych, tj. liściaków (ostrzy) świderskich, drapaczy i rylców, pokazała, że ich rozrzut wokół obiektów archeologicznych nie jest przypadkowy i wskazuje on na zróżnicowanie w zakresie funkcjonalnej organizacji przestrzeni przez ludność kultury świderskiej na stanowisku. Niniejsze badanie miało odpowiedzieć na pytanie dotyczące właściwości tego zróżnicowania. W tym celu przebadano mikroskopowo część dostępnego materiału. Chociaż stan zachowania zabytków mocno ograniczył możliwość przeprowadzenie analizy traseologicznej, to poczyniono szereg cennych obserwacji. Szczególnie interesujące wnioski dotyczyły liściaków i drapaczy. Dodatkowo, liściaki świderskie, jako miarodajna kategoria zabytków związanych z kulturą świderską, zostały przeanalizowane przez zastosowanie metod morfometrycznych (analiza przekroju poprzecznego ostrza, analiza kąta ostrza, morfometria geometryczna kształtu liściaków), a płynące z nich wnioski uzupełniły badania traseologiczne. Uzyskane wyniki pozwoliły na wskazanie wyróżniających się obszarów (strefy liściaków, drapaczy i rylców) oraz ich interpretację funkcjonalną.
This article is a study devoted to the spatial organization of a settlement of the Swiderian culture at Kraków-Bieżanów site 15. In the course of wide-scale rescue excavations (1999-2008), numerous lithic materials associated with this culture were discovered. They come from archaeological features such as the small kshemenitsa (KB-15/1 – feature 1) or spots of material clustering (features 2 and 3), they were collected as single finds. The spatialanalysis of the basic tool groups, i.e. Swiderian points, endscrapers and burins, showed that their distribution around archaeological objects wasnot accidental and points to diversity in functional space organization at the site. The aim of this investigation was to find the reason for the nature of this differentiation. For this purpose, a part of the available material has been studied by means of use-wear analysis. Although the state of preservation of lithics greatly reduced the possibility of carrying out functional analysis, a number of valuable observations were made. Particularly interesting were results concerning Swiderian points and endscrapers. In addition, Swiderian points, as the most intriguing category of typological tool related to the Swiderian culture, were analyzed by morphometric methods (tip cross-sectional area analysis, tip angle analysis, geometrics morphometrics) which were subjected to corroborated use-wear studies. The results obtained indicated the distictive areas (points, endscrapers and burins zones) and shed light on their functional interpretation.

Źródło:

Acta Archaeologica Lodziensia; 2017, 63; 7-27
0065-0986
2451-0300

Pojawia się w:

Acta Archaeologica Lodziensia

Dostawca treści:

Biblioteka Nauki

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Tytuł:

Charakterystyka pól naprężeń przed wierzchołkiem pęknięcia dla kwadratowej płyty poddanej dwuosiowemu rozciąganiu
Characteristic of the stress fields near crack tip for center cracked square plate in biaxial tension

Autorzy:

Grabania, M.

Powiązania:

https://bibliotekanauki.pl/articles/253275.pdf

Data publikacji:

2015

Wydawca:

Instytut Naukowo-Wydawniczy TTS

Tematy:

pole naprężeń
rozciąganie
materiał sprężysto-plastyczny
wierzchołek pęknięcia
stress field
stretching
elastic-plastic material
crack tip

Opis:

W artykule przedstawiona została charakterystyka pól naprężeń przed wierzchołkiem pęknięcia dla kwadratowej płyty zawierającej centralne pęknięcie, poddanej dwuosiowemu rozciąganiu. Praca prezentuje szczegóły obliczeń numerycznych, a także porównania stanów naprężeń dla płyt poddanych jednoosiowemu rozciąganiu oraz płyt poddawanych dwuosiowemu rozciąganiu. Analiza numeryczna prowadzona jest dla szeregu modeli materiałów sprężysto-plastycznych oraz różnych względnych długości pęknięcia. Dyskusja dotyczy wpływu geometrii, poziomu i rodzaju obciążenia zewnętrznego oraz charakterystyki materiałowej na pole naprężeń przed wierzchołkiem pęknięcia.
In the paper the stress field near front of crack for center cracked square plate in biaxial tension was pre-sented. The paper presents the details of numerical calculations, and also the comparison of states of stress for plates subjected to uniaxial tensile and plates to be in biaxial tension. The influence of the crack length, material characteristic and the level or type of external load were discussed.

Źródło:

TTS Technika Transportu Szynowego; 2015, 12; 585-592, CD
1232-3829
2543-5728

Pojawia się w:

TTS Technika Transportu Szynowego

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 48.

Tytuł:

Stability assessment as a criterion of stabilization of the movement trajectory of mobile crane working elements

Autorzy:

Kacalak, W.
Budniak, Z.
Majewski, M.

Powiązania:

https://bibliotekanauki.pl/articles/265654.pdf

Data publikacji:

2018

Wydawca:

Uniwersytet Zielonogórski. Oficyna Wydawnicza

Tematy:

dźwig samojezdny
stabilność żurawia
udźwig
mobile crane
stability of crane
overturning torque
lifting capacity
tip-over axis

Opis:

The article presents a stability assessment method of the mobile crane handling system based on the safety indicator values that were accepted as the trajectory optimization criterion. With the use of the mathematical model built and the model built in the integrated CAD/CAE environment, analyses were conducted of the displacements of the mass centre of the crane system, reactions of the outrigger system, stabilizing and overturning torques that act on the crane as well as the safety indicator values for the given movement trajectories of the crane working elements.

Źródło:

International Journal of Applied Mechanics and Engineering; 2018, 23, 1; 65-77
1734-4492
2353-9003

Pojawia się w:

International Journal of Applied Mechanics and Engineering

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 49.

Tytuł:

Opodatkowanie i oskładkowanie napiwków — glosa do wyroku Sądu Najwyższego z 13.09.2018 r. (II UK 343/17),
Taxation and contributions in respect of tips — a gloss to the judgment of the Supreme Court of 13 September 2018 (II UK 343/17)

Autorzy:

Morawski, Wojciech
Wantoch-Rekowski, Jacek

Powiązania:

https://bibliotekanauki.pl/articles/1835964.pdf

Data publikacji:

2019-10-31

Wydawca:

Polskie Wydawnictwo Ekonomiczne

Tematy:

napiwek
podatek dochodowy od osób fizycznych
składki na ubezpieczenia społeczne
tip
income tax on natural persons
social security contributions

Opis:

Przedmiotem glosy jest wyrok Sądu Najwyższego z 13.09.2018 r., w którym dokonano kwalifikacji prawnej napiwku — na płaszczyźnie ustawy o podatku dochodowym od osób fizycznych i ustawy o systemie ubezpieczeń społecznych. Orzeczenie nie może być uznane za prawidłowe, ponieważ Sąd Najwyższy sformułował tezę o źródłach finansowania podatku i składek bez odwołania się do przepisów, poprzestając na intencjach „napiwkodawcy” jako kluczowym czynniku kształtującym prawa i obowiązki płatnika.
The subject of the opinion is the Supreme Court ruling of 13.09.2018, which provides for the legal qualification of a tip – based on the Act on Income Tax from Natural Persons and the Act on the Social Insurance System. The ruling cannot be considered correct because the Supreme Court formulated a thesis on the sources of tax and contributions financing without referring to the regulations, confining itself to the intentions of the "tip provider" as a key factor influencing the rights and obligations of the payee.

Źródło:

Przegląd Ustawodawstwa Gospodarczego; 2019, 10; 39-44
0137-5490

Pojawia się w:

Przegląd Ustawodawstwa Gospodarczego

Dostawca treści:

Biblioteka Nauki

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Skocz do pozycji: 50.

Tytuł:

Ocena trwałości zmęczeniowej końcówki drążka kierowniczego
Experimental assessment of fatigue durability of steering rod tip

Autorzy:

Szymczak, T.
Brodecki, A.
Kowalewski, Z.
Lasota, P.

Powiązania:

https://bibliotekanauki.pl/articles/107581.pdf

Data publikacji:

2018

Wydawca:

Instytut Transportu Samochodowego

Tematy:

przegub
zmęczenie
obciążenie zmienne cyklicznie
liczba cykli
trwałość
pęknięcie
rod tip
fatigue
cyclic loading
number of cycles
durability
crack

Opis:

W pracy zaprezentowano wyniki badań trwałościowych końcówki drążka kierowniczego pojazdu o dmc powyżej 3.5 tony. W badaniach wykorzystywano wielkogabarytową platformę wibroizolowaną, serwohydrauliczny siłownik mobilny oraz cyfrowy kontroler sygnałów IST Instron. Próby prowadzono w warunkach działania obciążenia zmiennego cyklicznie do uzyskania 2×10⁶ cykli. Ze względu na kompleksową ocenę zachowania końcówki drążka kierowniczego testy przerywano, by wykonywać oględziny obiektu badań. Wyznaczono zmiany kąta wychylenia oraz momentu siły w funkcji liczby cykli oraz przedstawiono ich prognozę. Omówiono procedurę badawczą służącą ocenie trwałości przegubu kulistego.
The paper reports results from test of steering rod tip used in car having permissible total mass above 3.5 t. Anti-vibration platform, servo-hydraulic actuator and digital controller IST Instron were used to execute the tests. The experiments were carried out under cyclic loading up to 2×10⁶ cycles. The tests were interrupted for inspecting the examined object. Variations of angle and force moment and prediction of their values versus number of cycles are presented. Details of experimental procedure for evaluation of steering rod tip are provided.

Źródło:

Transport Samochodowy; 2018, 2; 63-72
1731-2795

Pojawia się w:

Transport Samochodowy

Dostawca treści:

Biblioteka Nauki

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