Wyniki wyszukiwania - Biblioteka Nauki

1

Nanoscale heat transport

100%

Bodzenta J.

Materials Science Poland

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2008

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tom Vol. 26, No. 1

97--103

EN

New physical phenomena connected with heat transport in structures with dimensions comparable with characteristic lengths of energy carriers are briefly reviewed. Problems with basic physical understanding of mechanisms responsible for energy transport in such structures are considered. In particular, the role of boundaries is discussed. Thermal properties of a few structures which dimensions influence heat transport, namely: superlattices and multilayered systems, nanoporous materials and nanotubes are analyzed. Problem of hot spots in electronic devices is also mentioned. The last part of the paper is devoted to methods of experimental investigation of thermal properties of nanostructures. Capabilities and shortcomings of two relatively new experimental techniques: picosecond reflectance thermometry and scanning thermal microscopy have been discussed.

2

Nano-Scale Structure Investigation of Vapour Deposited AlCrSiN Coating Using Transmission Electron Microscope Techniques

88%

Lukaszkowicz K. , Labisz K. , Basiaga M. , Jonda E.

Archives of Metallurgy and Materials

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2016

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tom Vol. 61, iss. 2A

837--842

EN

The investigations concerned the structural analysis of the AlCrSiN coating deposited by arc Physical Vapour Deposition method on the X40CrMoV5-1 hot work tool steel substrate. The deposition process was carried out on a device equipped with a technique of lateral, rotating cathodes. The nano/microstructure, phase identification and chemical state of the coating were analysed by high-resolution transmission electron microscopy. It was found that the investigated coatings have nanostructured nature consisting of fine crystallites. The fractographic tests were made using the scanning electron microscope and allow to state, that the coating was deposited uniformly and tightly adhere to the substrate material. In the work is presented the nature of a transition zone between the produced AlCrSiN coating and substrate material.

3

Quantum-Classical Calculations of the Nanomechanical Properties of Metals

75%

Dziedzic J.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2009

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tom Vol. 13, No 3

207-310

EN

Molecular-dynamics (MD) simulations constitute an important tool in the study of nanoscale metallic systems, especially so in the face of the difficulties plaguing their experimental analysis. Main limitations of the MD method stem from the empirical nature of the potentials employed, their functional form which is postulated ad hoc, and its classical nature. The neglect of electronic effects and the unjustified utilization of the potential for system configurations significantly different from those, for which the potential was parametrized makes the results of strictly classical calculations dubious, at least for a certain class of systems. On the other hand, high computational complexity of quantum-based methods, where atomic interactions are described ab initio, prohibits their direct use in the study of systems larger than several tens of atoms. In the last decade, a growing popularity of so-called hybrid (or cross-scaling) methods can be observed, that is, methods which treat the most interesting part of the system with a quantum-based approach, while the remainder is treated classically. Physically sound handshaking between the two methodologies (quantum and classical) within a single simulation constitutes a serious challenge, the majority of difficulties concentrating around the interface between the fragments of the system treated with the two methods. The aforementioned interface is most easily constructed for covalently bonded systems, where the bonds cut by the isolation of the quantum-based region can be saturated by the introduction of specially crafted link-atoms. In metallic systems, however, due to electronic delocalization, this traditional approach cannot be employed. This paper describes a physically sound and adequately efficient computational technique, which allows for the inclusion of results of locally employed quantum-based computations within a molecular-dynamics simulation, for systems described by the many-body Sutton-Chen (SC) potential, used in the study of fcc metals. The proposed technique was developed taking as a point of departure the Learn-on-the-Fly (LOTF) formalism, a recent development itself. The original LOTF approach is only suitable for two- or three-body potentials and is serial in nature, whereas the proposed technique can be used with many-body potentials and is parallel-ready. An implementation of the proposed approach in the form of computer code, which allows for parallel hybrid computations for metallic systems is also described. Finally, results from a set of hybrid simulations of nanoindentation of a copper workmaterial with a hard indenter utilizing the aforementoned technique and computer code is presented, as evidence of its viability.

4

Projekt stanowiska badawczego do testowania mikro i nano-skrawania w warunkach próżni i niskich temperatur

75%

Musiał W. , Dziedzic J. , Rybicki J. , Kordowska M.

Mechanik

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2014

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tom R. 87, nr 2CD

PL

Rozwój informatyki w ostatnich kilku dekadach umożliwił intensyfikację obliczeń komputerowych na poziomie molekularnym. Modelowanie zjawisk fizycznych przy pomocy komputera umożliwiło weryfikację i nowe podejście do wiedzy teoretycznej dotyczącej praw fizyki i umożliwiło ich analizę na poziomie atomowym. Współcześnie symulacje komputerowe używane są nie tylko do sprawdzania i weryfikowania teorii naukowych, ale również aby przewidywać wyniki eksperymentów i umożliwiać opisywanie i identyfikowanie modeli rzeczywistych procesów. Modele molekularne umożliwiają wykorzystywanie symulacji również do analizy skrawania w nanoskali.

EN

The last several decades have witnessed the flourishing and maturing of computer simulation. Modelling physical phenomena by means of a computer has acquired a status of a discipline in its own right, along the age-old theoretical and empirical approaches. Today, simulation is used not only to validate the predictions of theory and the results of experiment, it also has predictive capacity of its own, describing the exact behavior of simplified models of actual systems. Low cost and relative simplicity constitute major advantages of the simulation approach over experimental analysis when nanoscale systems are considered.

5

Synthesis, spectroscopic and thermogravimetric interpretations of UO2(II), ZrO(II), Zr(IV), VO(II) and V(V) ciprofloxacin antibiotic drug complexes

63%

Albedair L. A.

Polish Journal of Chemical Technology

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2021

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tom Vol. 23, nr 1

45--52

EN

New five ciprofloxacin (CIP) complexes of dioxouranium(II), oxozirconium(II), zirconium(IV), oxovanadium(II) and vanadium(IV) in the proportion 1:2 have been prepared using CIP as a drug chelate with UO2(NO3)2. 6H2O, ZrOCl2. 8H2O, ZrC4, VOSO4. xH2O and V2O5 respectively. The CIP complexes have been characterized based on the elemental analysis, molar conductance, magnetic, (FTIR & 1HNMR) spectral and thermal studies. The molar conductance studies of the synthesized complexes in DMSO solvent with concentration of 10–3 M indicate their non-electrolytic properties. At room temperature, the magnetic moment measurements revealed a diamagnetic behavior for all CIP prepared complexes. The different formulas of the new complexes can be represented as [UO2(CIP)2(NO3)2] (I), [VO(CIP)2(SO4)(H2O)] (II), [V2(O)(O2)2(CIP)2] (III), [Zr(O)(CIP)2(Cl)2] (IV), and [Zr(CIP)2(Cl)4] (V). The thermal analysis data of the complexes indicates the absence of coordinated water molecules except for vanadyl(II) complex (II). The CIP chelate is a uni-dentate ligand coordinated to the mentioned metal ion through terminal piperazinyl nitrogen. The transmission electron microscopy (TEM) investigation confirms the nano-structured form of the complexes.

6

Sources and the perspectives of the nanosciences and the nanotechnology

63%

Giergiel J.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

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2006

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tom z. 31

23-30

EN

History like to repeat itself. The world has originated in nano scale. The first cells were appeared 4,5 bilion years ago. Then micro and macro organisms were created. Nowadays there exist macro organisms and macro devices which are in turn made in minature to micro scale. From the micro scale we descend to the nano scale.

7

Analysis of damage processes in nanopillar arrays with hierarchical load transfer

63%

Derda T.

Journal of Applied Mathematics and Computational Mechanics

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2016

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tom Vol. 15, nr 3

27--36

EN

A computational model for the damage analysis in the axially loaded nanopillar arrays was developed on the basis of the Fibre Bundle Model and hierarchical load sharing protocol. The nanopillars are characterised by random strength-thresholds drawn according to the nanoscale Weibull statistics. We study the influence of the coordination number and the number of hierarchy levels on the system strength, size of the catastrophic avalanche and probability of breakdown.

8

Boundary conditions on the bio-cell surfaces for nanolubrication of microbearings

63%

Wierzcholski K.

Journal of KONES

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2007

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tom Vol. 14, No. 3

603-610

EN

The aim of the paper is the formulation of boundary conditions for liquid velocity and friction forces in nano scale and presentation of analogies between boundary conditions for super thin liquid layer about 100nm height around cultivated cell of cartilage human joint in bioreactor and boundary conditions for thin lubrication layer in micro bearing with no greater journal diameter than 2mm. To be considered flow of viscous liquid with non-Newtonian, viscoelastic properties in super thin boundary layer in direct contact with superficial layer of cultivated cells. Such flow is caused by the cell growth, weeping and suction process of the liquid from boundary thin layer into porous cell body. Liquid properties inside super thin layer depend above all from physical properties of bodies and surfaces which are restricted the thin liquid layer. It is specific feature of thin liquid layers which distinguishes such flows from lubrication flows where gap height reaches several dozen micrometers. Apparent viscosity of such liquid depends on shear rate which occur in thin boundary layer. Additional the dynamic viscosity of the liquid depends on Young modulus of cell superficial layer and on geometrical structure of the cell. Presented model of boundary conditions enables its application to the research connected with the optimal lubrication in slide micro bearings [6], [8].

PL

Tematem pracy jest sformułowanie warunków brzegowych dla prędkości cieczy i sił tarcia w nanoskali oraz przedstawienie analogii pomiędzy warunkami brzegowymi dla super cienkiej warstewki cieczy o wysokości poniżej 100 nm opływającej hodowane komórki chrząstki stawowej człowieka w bioreaktorze a warunkami brzegowymi dla cienkiej warstwy smarującej w mikro łożyskach o średnicy wału nieprzekraczającej 1mm. Rozpatrywany jest przepływ cieczy lepkiej o właściwościach nie Newtonowskich, lepko-sprężystych w super cienkiej warstwie granicznej występujący w bezpośrednim otoczeniu warstwy wierzchniej hodowanego chondrocytu. Taki przepływ jest wywołany między innymi wzrostem komórki, a także procesem przesączania się cieczy odżywczej z cienkiej warstwy granicznej do porowatego ciała komórek. Własności cieczy w super cienkiej warstwie zależą przede wszystkim od właściwości fizycznych ciałścianek lub powierzchni ograniczającej tak cienką warstewkę. Jest to specyfika przepływu w super cienkich warstewkach odróżniająca te przepływy od klasycznych przepływów smarujących gdzie wysokość szczeliny osiąga kilkanaście mikrometrów. Lepkość pozorna takiej cieczy zależy od prędkości deformacji, a więc od prędkości przepływu tej cieczy w cienkiej warstwie granicznej. Ponadto lepkość takiej cieczy zależy od modułu Younga warstwy wierzchniej oraz od struktury geometrycznej powierzchni hodowanego chondrocytu. Przedstawiony model warunków brzegowych umożliwia jego zastosowania do badań związanych z optymalnym smarowaniem mikro-łożysk ślizgowych.

9

Optymalizacja banków filtrów z przełączanymi prądami dla technologii CMOS w nano-skali

51%

Naumowicz M. , Handkiewicz A. , Szczęsny S.

Przegląd Elektrotechniczny

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2016

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tom R. 92, nr 9

81--83

PL

W artykule omówiono problem projektowania i optymalizowania układów analogowych pracujących w trybie przełączanych prądów. Technologia CMOS z tranzystorami o rozmiarach kanałów mniejszych niż kilka dziesiątek nm. jest wzięta pod uwagę. Zaprezentowano metodę optymalizacji charakterystyki częstotliwościowej z uwzględnieniem eliminacji zjawiska offsetu w odpowiedzi czasowej analogowych układów scalonych. Procedura projektowania bazuje na algorytmie Hooke'a-Jeeves'a zmodyfikowanym pod kątem optymalizacji dyskretnej. Wyniki przedstawiono dla pary filtrów piątego rzędu pracującej w trybie przełączanych prądów. Otrzymane rezultaty niemal całkowicie pokrywają się z charakterystykami idealnymi, świadcząc o skuteczności zaproponowanej metody optymalizacji.

EN

In the paper the problem of design and optimization of analog circuits, operating in switched current mode, is described. The CMOS technology with transistors of channel dimensions smaller than several tens of nm is taking into account. A method to optimize the frequency response with regard to the offset elimination in the time response of analog integrated circuits is presented. The procedure is based on the Hooke- Jeeves algorithm modified for discrete optimization. The results are shown for a fifth-order filter pair operating in the switched current mode. The results almost completely coincide with the ideal frequency response, demonstrating the effectiveness of the proposed optimization methods.

10

ADC z w pełni różnicowym integratorem w trybie prądowym

51%

Handkiewicz A. , Naumowicz M. , Kropidłowski M. , Szczęsny S.

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2018

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tom R. 94, nr 9

22--25

PL

Przedmiotem pracy są przetworniki ADC w trybie prądowym dla standardowych, cyfrowych technologii CMOS w nanoskali. Wykazano, że taki przetwornik z integratorem prądowym o strukturze różnicowej daje kilkubitową dokładność konieczną dla przetwarzania potokowego. W pracy zaprezentowano realizację w pełni różnicową pozwalającą na zwiększenie rozdzielczości przetwornika o dodatkowy bit.

EN

The subject of the work are ADC converters in current mode for standard digital CMOS technology at the nanoscale. It was shown that such a converter with a current integrator with a differential structure gives several-bit accuracy necessary for pipelined processing. The paper presents a fully differential implementation that allows to increase the resolution of the converter by an additional bit.