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Tytuł:
Struktury planarnych matryc Butlera w układzie demonstratora technologii namiaru źródeł promieniowania mikrofalowego
Butler planar matrix structures in a technology demonstrator system for direction finding of microwave radiation sources
Autorzy:
Chudy, Z.
Powiązania:
https://bibliotekanauki.pl/articles/153724.pdf
Data publikacji:
2011
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
źródła promieniowania elektromagnetycznego
namiar
kołowy szyk anten
matryca Butlera
electromagnetic radiation sources
direction finding system
circular antennas array
Butler matrix
Opis:
Nowe typy systemów odbiorczych umożliwiających wykrycie i analizę sygnałów emitowanych przez występujące emitery energii elektromagnetycznej to urządzenia, które gwarantują określenie częstotliwości nośnej wykrytego sygnału, określenie namiaru na ZE tj. źródło sygnału oraz innych parametrów charakterystycznych z jednoczesnym przetwarzaniem i rejestracją tych danych. Sugerowane rozwiązanie układowe to przykład szerokopasmowego systemu bez przeszukiwania pracującego w trybie monoimpulsowym.
The new types of receiver systems enable detection and analysis of the signals emitted by electromagnetic sources. They are systems which guarantee determining the carrier frequency of the finding, defining the direction finding of the signal source and well as other specific parameters with simultaneous data processing and recording . The proposed system solution is an example of the broadband system with no scanning mode working in monoimpulse mode. Data from monitoring of the electromagnetic environment with data from analysing and identifying radar emissions are necessary for taking a decision concerning the situation on earth, at see, as well as in the air, by services responsible for "on-line" checking the condition of electromagnetic surroundings. The equipment used in such systems should analyse, classify and identify detected signals very fast to determine the level of danger. Besides identifying, these system are used for immediate warning about scanning with an electromagnetic beam. The presented experimental model for identification-warning systems can be used in stationary as well as portable systems (for example: on vehicles, in plane and in ship) thanks to its small dimensions. Taking into considerations the working band, the obtained accuracy of localisation and the monopulse operation regime one can summarise that the presented system can be very efficient for detecting the short-time emission.
Źródło:
Pomiary Automatyka Kontrola; 2011, R. 57, nr 11, 11; 1363-1367
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kluczowe zalety i ograniczenia macierzowych struktur organizacyjnych
The Key Advantages and Disadvantages of Matrix Organizational Structures
Autorzy:
Goś, Krzysztof
Powiązania:
https://bibliotekanauki.pl/articles/1810861.pdf
Data publikacji:
2015-11-15
Wydawca:
Uniwersytet Warszawski. Wydawnictwo Naukowe Wydziału Zarządzania
Tematy:
matrix structures
matrix organizations
matrix management
cross-functional
structures
struktury macierzowe
organizacje macierzowe
zarządzanie macierzowe,
zespoły międzyfunkcyjne
Opis:
ograniczeń koncepcji macierzowych struktur organizacyjnych. Po krótkim wprowadzeniu do dziedziny zidentyfikowano w nim i omówiono osiem kluczowych cech organizacji macierzowych. Przeprowadzona analiza publikacji wykazała, że trzy ze wspomnianych cech są przeważnie postrzegane jako zalety organizacji macierzowych, jedna jako ich ograniczenie, zaś pozostałe cztery budzą kontrowersje wśród teoretyków co do ich pozytywnego bądź negatywnego charakteru. Owe kontrowersyjne cechy wskazano jako proponowany obszar do dalszych badań.
The article is a review of the literature on the key advantages and disadvantages of matrix organizational structures. After providing a brief introduction into the discipline, it identifies and discusses eight major characteristics of matrix organizations. In the reviewed publications, three characteristics are considered primarily as advantages of matrix structures, one as a disadvantage, whereas the four remaining arouse controversies as to their beneficial or negative nature. The controversial characteristics are indicated as a field for further investigation.
Źródło:
Studia i Materiały; 2015, 2/2015 (19); 66-83
1733-9758
Pojawia się w:
Studia i Materiały
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling DNA and RNA secondary structures using matrix insertion-deletion systems
Autorzy:
Kuppusamy, L.
Mahendran, A.
Powiązania:
https://bibliotekanauki.pl/articles/330807.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
biomolecular structure
insertion deletion system
intermolecular
intramolecular
secondary structure
struktura biomolekularna
struktura międzycząsteczkowa
struktura wtórna
Opis:
Insertion and deletion are operations that occur commonly in DNA processing and RNA editing. Since biological macromolecules can be viewed as symbols, gene sequences can be represented as strings and structures can be interpreted as languages. This suggests that the bio-molecular structures that occur at different levels can be theoretically studied by formal languages. In the literature, there is no unique grammar formalism that captures various bio-molecular structures. To overcome this deficiency, in this paper, we introduce a simple grammar model called the matrix insertion–deletion system, and using it we model several bio-molecular structures that occur at the intramolecular, intermolecular and RNA secondary levels.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2016, 26, 1; 245-258
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermally Stimulated Depolarization Current in Heterogeneous Structures. The Dielectric Matrix with Dielectric Spheres
Autorzy:
Poźniak, J.
Powiązania:
https://bibliotekanauki.pl/articles/1920683.pdf
Data publikacji:
1992-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.30.+d
Opis:
Theoretical analysis of the thermally stimulated depolarization current in heterogeneous structure is performed. Two systems are considered: (i) a single dielectric sphere in dielectric matrix and (ii) a continuous dielectric medium containing sparsely distributed dielectric spheres (Wagner-Voigt model of heterogeneous dielectric. The existence of the interfacial charge is taken into account. The equations are found which describe the dependence of the thermally stimulated depolarization current density on the polarization conditions and on the electrical properties of the both materials.
Źródło:
Acta Physica Polonica A; 1992, 81, 4-5; 589-597
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Macierzowa struktura organizacyjna i jej wykorzystanie w zarządzaniu projektami
Matrix Organization Structure and its use in Project Managing
Autorzy:
Pawlak, Marek
Powiązania:
https://bibliotekanauki.pl/articles/1853508.pdf
Data publikacji:
2005
Wydawca:
Katolicki Uniwersytet Lubelski Jana Pawła II. Towarzystwo Naukowe KUL
Tematy:
zarządzanie projektami
struktury organizacyjne
struktura macierzowa
project management
organization structures
matrix structure
Opis:
The article is devoted to one of the typical organization structures used in project managing, i.e. the matrix structure. On the basis of research into subject literature its characteristic features, and advantages and disadvantages are described. In particular, the form of this structure, the distribution of roles between project managers and line managers, their duties, typical causes of conflicts, and rules of coordination and cooperation are discussed. Also some varieties of matrix structures are presented. Next, ideal conditions are specified in which the matrix structure may be applied and the problems that are connected with its use. One of the conditions of implementation of this kind of structure is the proper organization culture. The advantages and disadvantages of the structure are discussed considering such questions as: the very project, its manager, functional cells and project personnel.
Źródło:
Roczniki Nauk Społecznych; 2005, 33, 3; 117-139
0137-4176
Pojawia się w:
Roczniki Nauk Społecznych
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic structures of CdSe quantum dots embedded in ZnSe
Autorzy:
Jayawardhana, M. R. P. I.
Wijewardena Gamalath, K. A. I. L.
Powiązania:
https://bibliotekanauki.pl/articles/1178287.pdf
Data publikacji:
2017
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
LCAO method
Quantum dot
Sparse matrices
adjacency matrix
folded spectrum method
optical matrix elements
strain effects
valence band offset
Opis:
The electronic structures and optical matrix elements of CdSe semiconductor quantum dots of near cubical, hemispherical and cylindrical shape embedded in ZnSe were calculated. Bulk Hamiltonian matrices were obtained using the empirical tight binding method including spin-orbital coupling and relativistic effects. All quantum dots were simulated in reciprocal space and the number of atoms in each quantum dot was kept nearly equal for the comparison purpose. An adjacency matrix was produced which indicates the adjacencies of unit cells and the bulk Hamiltonian was included for each adjacency point in order to obtain the quantum dot Hamiltonians. The strain effects, valence band offset and spin orbital coupling were included in the calculations. The quantum dot Hamiltonian was solved to obtain the highest and lowest eigenvalues from which the electronic structure was obtained. Then eigenvalues near integers ranging from the lowest eigenvalue to highest eigenvalue was generated for the point.
Źródło:
World Scientific News; 2017, 86, 3; 205-225
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some Algebraic Structures of Picture Fuzzy Matrices
Autorzy:
Silambarasan, I.
Powiązania:
https://bibliotekanauki.pl/articles/1031777.pdf
Data publikacji:
2020
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Algebraic product
Algebraic sum
Exponentiation operations
Intuitionistic fuzzy matrix
Picture fuzzy matrix
Scalar multiplication
Opis:
In this paper, the concept of Picture fuzzy matrices, which are direct extensions of an intuitionistic fuzzy matrices. Then we define some algebraic operations of Picture fuzzy matrices, such as max-min, min-max, complement, algebraic sum, algebraic product, scalar multiplication (nA) and exponentiation (A^n). We also investigate their algebraic properties of these operations. Furthermore, we define a new operation(@) on Picture fuzzy matrices and discuss distributive laws in the case where the operations of ⊕_℘,〖 ⊗〗_℘,〖 ∧〗_℘ and ∨_℘ are combined each other.
Źródło:
World Scientific News; 2020, 150; 78-91
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Buildings Materials & Structures Based on Advanced Polymer Nanostructured Matrix
Autorzy:
Gizelter, R.
Powiązania:
https://bibliotekanauki.pl/articles/411525.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
RubCon
butadiene rubber
natural rubber
rubber industry
Opis:
Development of manufacture of linear diene oligomers belonging to a liquid rubbers class with viscous liquids consistence allowed to create a new class of conglomerate polymer composite materials - rubber concrete (RubCon®). Rubber concrete is the advanced constructional material created for last years. It is polymer concrete with a unique set of physical-mechanical, chemical and technological properties which allow to obtain highly effective building structures and products on its basis.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2014, 9; 103-114
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Risk Assessment Approaches for Offshore Structures
Autorzy:
Shouman, M.
Ghoneim, N. I.
El-Khatib, M.
Powiązania:
https://bibliotekanauki.pl/articles/1841492.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
offshore structures
risk assessment
QRA
hazard identification
offshore platform
risk matrix
risk index
formal safety assessment
Opis:
Risk assessment and management was established as a scientific field some 30–40 years ago. Principles and methods were developed for how to conceptualize, assess, and manage risk. These principles and methods still represent largely the foundation of this field today, but many advances have been made, linked to both the theoretical platform and practical models and procedures. The purpose of the thesis is to perform a review of these advances, with a special focus on the fundamental ideas and thinking on which these are based. We have looked for trends in perspectives and approaches, and we reflect on where further development of the risk field is needed and should be encouraged. The present study is written for readers with different types of background, not only for experts on risk. However, there is a conflict between the cost impact and safety aspect. E&P managers as well as government supervisor authorities are constantly faced with decisions to be made regarding of safety. In order to ensure comparability and to set priorities application of QRA is a useful tool to justify choices made with regard to personnel safety, environmental protection, asset damage and business reputation, it is recommended to apply the systematic cause analysis method and develop the risk management models which contains an integral approach toward the health, safety and environmental aspect.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2021, 15, 2; 401-406
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic core-shell structures as potential carriers in drug delivery system
Autorzy:
Łuszczyk, K.
Powiązania:
https://bibliotekanauki.pl/articles/1190035.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
nanocząstki magnetyczne
matryca krzemionkowa
struktura typu rdzeń-otoczka
magnetic nanoparticles
silica matrix
core-shell structure
drug delivery
Opis:
Magnetic core-shell structures have a high potential for promising application in biomedicine as drug carriers. In this paper, magnetic core-shell structure obtained by the sol-gel method was presented. In order to provide the protective coating of magnetic MnFe2O4 nanoparticles, amorphous silica was used. It has been shown that magnetic core was successfully encapsulated in SiO2 matrix and that the received core-shell material had magnetic properties.
Źródło:
Interdisciplinary Journal of Engineering Sciences; 2014, 2, 1; 1--4
2300-5874
Pojawia się w:
Interdisciplinary Journal of Engineering Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On fault tolerant control structures incorporating fault estimation
Autorzy:
Krokavec, D.
Filasová, A.
Liščinský, P.
Powiązania:
https://bibliotekanauki.pl/articles/229298.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
linear systems
fault tolerant control
fault estimation
linear matrix inequalities
H∞ norm
H2/H∞ control strategy
Opis:
The paper provides the minimal necessary modifications of linear matrix inequality conditions for the mixed H2/H∞ control design as well as for the augmented observer-based fault estimation to be mutually compatible in joint design of integrated fault estimation and fault tolerant control. To be possible, within this integration, to design the controller which guarantees a pre-specified H∞ norm disturbance attenuation level, the design conditions has to be regularized using the H2 performance index and, moreover, augmented fault observer must be of enforced dynamics. Analyzing the ambit of performances given on the mixed H2/H∞ design, the joint design conditions are formulated as a minimization problem subject to convex constraints expressed by a system of LMIs. The feasibility of the conditions is demonstrated by a numerical example.
Źródło:
Archives of Control Sciences; 2016, 26, 4; 453-469
1230-2384
Pojawia się w:
Archives of Control Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wybrane struktury niezawodnościowe systemów sygnalizacji pożaru dla scenariusza pożarowego i realizacji sprzętowej
Selected structures of reliability structures of fire signaling systems for fire scale and handling equipment
Autorzy:
Klimczak, T.
Paś, J.
Powiązania:
https://bibliotekanauki.pl/articles/310924.pdf
Data publikacji:
2017
Wydawca:
Instytut Naukowo-Wydawniczy "SPATIUM"
Tematy:
sygnalizacja pożarowa
system sygnalizacji pożarowej
scenariusz pożarowy
matryca sterowań
fire signaling systems
fire incident scenario
control matrix
Opis:
W artykule przedstawiono zasadę działania i strukturę techniczną elektronicznego systemu bezpieczeństwa - tj. systemu sygnalizacji pożarowej, który eksploatowany jest w budynku nastawni LCS. Budynek zlokalizowany jest na rozległym obszarze kolejowym. Najbardziej istotnym urządzeniem przeciwpożarowym dla scenariusza pożarowego jest system sygnalizacji pożarowej, który pełni role integratora wszystkich urządzeń przeciwpożarowych, technicznych i technologicznych w budynku. Opracowany scenariusz pożarowy realizowany jest w oparciu o adresowalną, mikroprocesorową centralę sygnalizacji pożarowej. Dla wybranej struktury technicznej realizującej założony scenariusz pożarowy zaproponowano określone struktury niezawodnościowe, które umożliwiają określenie dopuszczalnych wartości wskaźników niezawodnościowych dla danego rozwiązania technicznego.
The article presents the operating principle and technical structure of the electronic safety system - ie the fire alarm system which operates the LCS control room. The building is located on a vast railway area. The most important fire safety device for a fire scenario is the fire alarm system, which plays an integral role in all fire, technical and technological equipment in the building. The developed fire scenario is based on an addressable, microprocessor fire alarm panel. For the selected technical structure that implements the assumed fire scenario, certain reliability structures have been proposed that allow for the determination of acceptable reliability levels for a given technical solution.
Źródło:
Autobusy : technika, eksploatacja, systemy transportowe; 2017, 18, 12; 956-961, CD
1509-5878
2450-7725
Pojawia się w:
Autobusy : technika, eksploatacja, systemy transportowe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inversion of selected structures of block matrices of chosen mechatronic systems
Autorzy:
Trawiński, T.
Kochan, A.
Kielan, P.
Kurzyk, D.
Powiązania:
https://bibliotekanauki.pl/articles/202402.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
arrowhead matrices
mechatronic systems
matrix inversion
computational complexity
systemy mechatroniczne
złożoność obliczeniowa
grupy macierzy
macierz inwersji
Opis:
This paper describes how to calculate the number of algebraic operations necessary to implement block matrix inversion that occurs, among others, in mathematical models of modern positioning systems of mass storage devices. The inversion method of block matrices is presented as well. The presented form of general formulas describing the calculation complexity of inverted form of block matrix were prepared for three different cases of division into internal blocks. The obtained results are compared with a standard Gaussian method and the “inv” method used in Matlab. The proposed method for matrix inversion is much more effective in comparison in standard Matlab matrix inversion “inv” function (almost two times faster) and is much less numerically complex than standard Gauss method.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2016, 64, 4; 853-863
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The application of volume texture extraction to three-dimensional seismic data – lithofacial structures exploration within the Miocene deposits of the Carpathian Foredeep
Autorzy:
Łukaszewski, Mariusz
Powiązania:
https://bibliotekanauki.pl/articles/1841768.pdf
Data publikacji:
2020
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Carpathian Foredeep
channel system
seismic attributes
machine learning
Grey Level Co-occurrence Matrix
Opis:
There are numerous conventional fields of natural gas in the Carpathian Foredeep, and there is also evidence to suggest that unconventional gas accumulations may occur in this region. The different seismic signatures of these geological forms, the small scale of amplitude variation, and the large amount of data make the process of geological interpretation extremely time consuming. Moreover, the dispersed nature of information in a large block of seismic data increasingly requires automatic, self-learning cognitive processes. Recent developments with Machine Learning have added new capabilities to seismic interpretation, especially to multi-attribute seismic analysis. Each case requires a proper selection of attributes. In this paper, the Grey Level Co-occurrence Matrix method is presented and its two texture attributes: Energy and Entropy. Haralick’s two texture parameters were applied to an advanced interpretation of the interval of Miocene deposits in order to discover the subtle geological features hidden between the seismic traces. As a result, a submarine-slope channel system was delineated leading to the discovery of unknown earlier relationships between gas boreholes and the geological environment. The Miocene deposits filling the Carpathian Foredeep, due to their lithological and facies diversity, provide excellent conditions for testing and implementing Machine Learning techniques. The presented texture attributes are the desired input components for self-learning systems for seismic facies classification.
Źródło:
Geology, Geophysics and Environment; 2020, 46, 4; 301-313
2299-8004
2353-0790
Pojawia się w:
Geology, Geophysics and Environment
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Numerical Approach to Calculate the Radiation Efficiency of Baffled Planar Structures Using the Far Field
Autorzy:
González-Montenegro, M. A.
Jordan, R.
Lenzi, A.
Arenas, J. P.
Powiązania:
https://bibliotekanauki.pl/articles/176303.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
propagating matrix
far field
sound power
structural finite element analysis
Opis:
A numerical method is developed for estimating the acoustic power of any baffled planar structure, which is vibrating with arbitrary surface velocity profile. It is well known that this parameter may be calculated with good accuracy using near field data, in terms of an impedance matrix, which is generated by the discretization of the vibrating surface into a number of elementary radiators. Thus, the sound pressure field on the structure surface can be determined by a combination of the matrix and the volume velocity vector. Then, the sound power can be estimated through integration of the acoustic intensity over a closed surface. On the other hand, few works exist in which the calculation is done in the far field from near field data by the use of radiation matrices, possibly because the numerical integration becomes complicated and expensive due to large variations of directivity of the source. In this work a different approach is used, based in the so-called Propagating Matrix, which is useful for calculating the sound pressure of an arbitrary number of points into free space, and it can be employed to estimate the sound power by integrating over a finite number of pressure points over a hemispherical surface surrounding the vibrating structure. Through numerical analysis, the advantages/disadvantages of the current method are investigated, when compared with numerical methods based on near field data. A flexible rectangular baffled panel is considered, where the normal velocity profile is previously calculated using a commercial finite element software. However, the method can easily be extended to any arbitrary shape. Good results are obtained in the low frequency range showing high computational performance of the method. Moreover, strategies are proposed to improve the performance of the method in terms of both computational cost and speed.
Źródło:
Archives of Acoustics; 2014, 39, 2; 249-260
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-performance quasi one-dimensional mirrors of mechanical waves built of periodic and aperiodic structures
Autorzy:
Garus, S.
Sochacki, W.
Powiązania:
https://bibliotekanauki.pl/articles/122921.pdf
Data publikacji:
2018
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
mechanical waves
phononic
reflectance
transfer matrix
band gap
fale mechaniczne
struktura okresowa
współczynnik odbicia
macierz transferu
pasmo wzbronione
Opis:
The work studied the reflectance for quasi one-dimensional phononical structures. In composite superlattices, the thickness of the layers, their arrangement and selection of constituent materials with appropriate properties such as the density and velocity of mechanical waves propagation allows for the creation of a phononic band gap (PhBG) phenomenon. PhBG is characterized by high reflectance of the mechanical wave incident on the analyzed structure, which means that the wave does not propagate in the superlattice. The paper proposes periodic and aperiodic structures characterized by a wide range of reflectance for the ultrasonic frequencies of mechanical waves and shows how the change the thickness of the layer affects the properties of the analyzed structures.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2018, 17, 4; 19-24
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Minimizing the number of layers of the quasi one-dimensional phononic structures
Autorzy:
Garus, Sebastian
Sochacki, Wojciech
Kubanek, Mariusz
Nabiałek, Marcin
Powiązania:
https://bibliotekanauki.pl/articles/2173523.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
mechanical waves
phononic
transfer matrix
band gap
genetic algorithm
fale mechaniczne
fononiczny
macierz przejścia
pasmo wzbronione
algorytm genetyczny
Opis:
In the work, multi-criteria optimization of phononic structures was performed to minimize the transmission in the frequency range of acoustic waves, eliminate high transmission peaks with a small half-width inside of the band gap, and what was the most important part of the work – to minimize the number of layers in the structure. Two types of the genetic algorithm were compared in the study. The first one was characterized by a constant number of layers (GACL) of the phononic structure of each individual in each population. Then, the algorithm was run for a different number of layers, as a result of which the structures with the best value of the objective function were determined. In the second version of the algorithm, individuals in populations had a variable number of layers (GAVL) which required a different type of target function and crossover procedure. The transmission for quasi-one-dimensional phononic structures was determined with the use of the transfer matrix method algorithm. Based on the research, it can be concluded that the developed GAVL algorithm with an appropriately selected objective function achieved optimal solutions in a much smaller number of iterations than the GACL algorithm, and the value of the k parameter below 1 leads to faster achievement of the optimal structure.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2022, 70, 1; e139394, 1--8
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the Alternative Structures for a Three-Grade Markov Manpower System
Autorzy:
Amenaghawon, Vincent A.
Ekhosuehi, Virtue U.
Osagiede, Augustine A.
Powiązania:
https://bibliotekanauki.pl/articles/1818653.pdf
Data publikacji:
2020
Wydawca:
Politechnika Rzeszowska im. Ignacego Łukasiewicza. Oficyna Wydawnicza
Tematy:
embeddability problem
manpower system
Markov chain
stochastic matrix
z-transform
problem z możliwością osadzania
system siły roboczej
łańcuch Markowa
macierz stochastyczna
Opis:
This paper considers a manpower system modelled withinthe Markov chain context under the condition that recruitment is doneto replace outgoing flows. The paper takes up the embeddability problemin a three-grade manpower system and examines it from the standpointof generating function (i.e., the z-transform of stochastic matrices). Themethod constructs a stochastic matrix that is made up of a limiting-stateprobability matrix and a partial sum of transient matrices. Examples areprovided to illustrate the utility of the method.
Źródło:
Journal of Mathematics and Applications; 2020, 43; 5--17
1733-6775
2300-9926
Pojawia się w:
Journal of Mathematics and Applications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
O miernikach konkurecyjności regionalnej
On Measures of Regional Competitiveness
Autorzy:
Ponikowski, Henryk
Powiązania:
https://bibliotekanauki.pl/articles/1856574.pdf
Data publikacji:
2004
Wydawca:
Katolicki Uniwersytet Lubelski Jana Pawła II. Towarzystwo Naukowe KUL
Tematy:
konkurencyjność regionalna
cechy konkurencyjności
wielowymiarowa macierz danych
mierniki struktur konkurencyjności
mierniki dystansów konkurencyjności
regional competitiveness
features of competitiveness
multidimensional matrix of data
measures of competitiveness structures
measures of competitiveness distances
Opis:
The article is concerned with quantification of the idea of regional competitiveness. The fact that a generally accepted definition is missing from the subject literature results in problems appearing in empirical studies, that are connected with measuring this category. We accept that regional competitiveness is the ability of the administrative system to effect changes in its inner quantitative structure, that is the number and intensity of elements that make up the region, and its qualitative structure, that is the kind and type of relations occurring between the elements of the region and its surrounding. Formulated in this way regional competitiveness is reduced to a measure of regional structures and distances.
Źródło:
Roczniki Nauk Społecznych; 2004, 32, 3; 241-247
0137-4176
Pojawia się w:
Roczniki Nauk Społecznych
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
O mechanizmie uszkodzenia mikrostruktury matrycy cementowej betonu obiektów oczyszczalni ścieków przemysłowych
On the mechanism of damage to the microstructure of the cement matrix of concrete in industrial liquid waste treatment structures
Autorzy:
Słomka-Słupik, B.
Zybura, A.
Powiązania:
https://bibliotekanauki.pl/articles/163215.pdf
Data publikacji:
2010
Wydawca:
Polski Związek Inżynierów i Techników Budownictwa
Tematy:
ścieki przemysłowe
ścieki agresywne
oczyszczalnia ścieków
zbiornik żelbetowy
chlorek amonu
matryca cementowa
uszkodzenie mikrostruktury
industrial sewage
aggresive sewage
sewage treatment plant
reinforced concrete tank
ammonium chloride
cement matrix
microstructure damage
Opis:
Trwałość betonu żelbetowych zbiorników oczyszczalni ścieków jest obniżana wieloma czynnikami - fizycznymi, chemicznymi i biologicznymi. W wodach poprodukcyjnych zakładów koksowniczych i zakładów sztucznych nawozów azotowych występują między innymi duże ilości jonów chlorkowych (CI-) i amonowych (NH4+). Zestaw tych jonów stanowi szczególnie niebezpieczne środowiska dla budowli żelbetawych. W artykule opisano mechanizmy uszkodzenia mikrostruktury matrycy cementowej spowodowane takimi właśnie czynnikami.
The durability of the concrete in reinforced-concrete tanks in liquid waste treatment facilities is reduced by many factors - physical, chemical and biological. In the waste water produced by coke plants and artificial nitrate fertilizer factories, there occur (among others) large quantities of chloride (CI) and ammonium [NH4) ions. The combination of these ions produces a particularly dangerous environment for reinforced-concrete structures. This paper describes the mechanisms of damage to the microstructure of the cement matrix caused by such factors.
Źródło:
Przegląd Budowlany; 2010, R. 81, nr 2, 2; 41-44
0033-2038
Pojawia się w:
Przegląd Budowlany
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on the influence of airflow resistance of layered porous structures on the sound absorption coefficient
Autorzy:
Flach, Artur
Powiązania:
https://bibliotekanauki.pl/articles/24201972.pdf
Data publikacji:
2022
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Tematy:
airflow resistance
anechoic wedges
transfer matrix method
optimization
PSO
particle swarm optimization
opór przepływu powietrza
kliny akustyczne
metoda macierzy przejścia
optymalizacja
optymalizacja roju cząstek
Opis:
The paper presents the research on the influence of airflow resistance on the sound absorption coefficient of layered porous structures. For the calculation of the sound absorption coefficient, the models of layered sound-absorbing structures were developed with the use of numerical computational models. Using the developed models, optimization was carried out to maximize the average sound absorption coefficient of the structures for a given frequency range. As a result of the research, the dependence of the change in airflow resistance for the successive layers of the material was determined. The results of the work will be particularly useful in the design of wedges used in anechoic chambers.
Źródło:
Vibrations in Physical Systems; 2022, 33, 3; art. no. 2022311
0860-6897
Pojawia się w:
Vibrations in Physical Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Hydrostatic Pressure on Photoluminescence Spectra from Structures with Si Nanocrystals Fabricated in SiO$\text{}_{2}$ Matrix
Autorzy:
Zhuravlev, K.
Tyschenko, I.
Vandyshev, E.
Bulytova, N.
Misiuk, A.
Rebohle, L.
Skorupa, W.
Powiązania:
https://bibliotekanauki.pl/articles/2035528.pdf
Data publikacji:
2002-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.Ac
73.63.Bd
78.67.-n
68.35.Fx
Opis:
The effect of hydrostatic pressure applied at high temperature on photoluminescence of Si-implanted SiO$\text{}_{2}$ films was studied. A "blue"-shift of PL spectrum from the SiO$\text{}_{2}$ films implanted with Si$\text{}^{+}$ ions to total dose of 1.2×10$\text{}^{17}$ cm$\text{}^{-2}$ with an increase in hydrostatic pressure was observed. For the films implanted with Si$\text{}^{+}$ ions to a total dose of 4.8×10$\text{}^{16}$ cm$\text{}^{-2}$ high temperature annealing under high hydrostatic pressure (12 kbar) causes a "red"-shift of photoluminescence spectrum. The "red" photoluminescence bands are attributed to Si nanocrystals while the "blue" ones are related to Si nanocrystals of reduced size or chains of silicon atoms or ≡Si-Si≡ defects. A decrease in size of Si nanocluster size occurs in result of the pressure-induced decrease in the diffusion of silicon atoms.
Źródło:
Acta Physica Polonica A; 2002, 102, 2; 337-344
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The relationship between the structural anisotropy of the PFA polymer/compressed expanded graphite-matrix composites and acoustic emission characteristics
Autorzy:
Berdowska, Sylwia
Berdowski, Janusz
Aubry, Frederic
Powiązania:
https://bibliotekanauki.pl/articles/2086891.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
acoustic emission
spectrum distribution
anisotropic structures
polyfurfuryl alcohol
compressed expanded graphite
composite membrane
emisja akustyczna
rozkład widma
struktura anizotropowa
alkohol polifurfurylowy
grafit ekspandowany prasowany
membrana kompozytowa
Opis:
The main aim of the study was to search for the relationship between the anisotropy of the structure of polyfurfuryl alcohol (PFA) – polymer/compressed expanded graphite (CEG)-matrix composites at subsequent stages of the technological process and characteristics of the acoustic emission (AE) descriptors. These composites, obtained after successive technological procedures of impregnation, polymerization, and carbonization, possess different structure, densities, porosity, and other physicochemical properties. In the structures of composites prepared on the basis of CEG, two basic directions can be distinguished: parallel to the bedding plane of graphite sheets and perpendicular to it. The measurements were carried out for the stress acting in these two main directions. The investigation has shown that the AE method enables the detection of anisotropy in the structure of materials. The results of the research show that all four of the acoustic emission descriptors studied in this work are sensitive to the technological stages of these materials on the one hand and their structure anisotropy on the other. Fourier analysis of the recorded spectra provides interesting conclusions about the structural properties of composites as well as a lot of information about the bonding forces between the carbon atoms of which the CEG matrix is composed and the PFA polymer or turbostratic carbon.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 5; e138235, 1--8
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impregnation studies and mechanical characterization of cellular, natural, fiber-reinforced, composite structures
Impregnacja włókien naturalnych i właściwości mechaniczne kompozytów z ich udziałem
Autorzy:
Geller, S.
Weissenborn, O.
Gude, M.
Czulak, A.
Powiązania:
https://bibliotekanauki.pl/articles/947013.pdf
Data publikacji:
2016
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Chemii Przemysłowej
Tematy:
natural fibers
fiber-reinforced plastics
polyurethane spray coat method
cellular matrix
włókna naturalne
tworzywa polimerowe wzmocnione włóknami
metoda warstwowego natrysku poliuretanu
matryca komórkowa
Opis:
With the use of natural fibers as a substitute for synthetic reinforcements, a significant contribution towards advanced ecological and efficient lightweight structures can be made.Within this article, the polyurethane (PUR) spray coat method is used for the manufacture of natural fiber-reinforced composites based on the fiber materials linen and hemp. Both the investigation of the mechanical properties and the yarn impregnation, as a reference for the composite quality, are of major interest and help to evaluate the potential of these bio-based materials as a contribution towards advanced lightweight components.
Kompozyty wzmocnione włóknami naturalnymi na bazie lnu i konopi wytwarzano metodą warstwowego natrysku poliuretanu (PUR). Zbadano proces impregnacji przędzy i właściwości mechaniczne otrzymanych kompozytów oraz oceniono możliwości zastosowania takich materiałów pochodzenia naturalnego w zaawansowanych lekkich elementach konstrukcyjnych.
Źródło:
Polimery; 2016, 61, 2; 125-132
0032-2725
Pojawia się w:
Polimery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
O występowaniu i wpływie na trwałość konstrukcji drewnianych, zmiennego w czasie modułu sztywności poprzecznej G
On the occurrence of the time-dependent shear modulus G and its effect on the durability of wooden structures
Autorzy:
Misztal, Barbara
Powiązania:
https://bibliotekanauki.pl/chapters/2194752.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
moduł sztywności poprzecznej
włókno drzewne
lepkosprężysta matryca
siła poprzeczna
shear modulus
wooden fibre
visco-elastic matrix
shear force
Opis:
W opracowaniu omówiono historyczne rozwiązania konstrukcji stosowane w celu zmniejszenia wpływu sił poprzecznych. Zaprezentowano model drewna jako naturalnego kompozytu włóknistego, zbudowanego z włókien umieszczonych w lepkosprężystej matrycy. Opisano badania na modelach wspornikowych z drewna, w celu pokazania trendu zmian ugięć i zmniejszenia wartości modułów sprężystości podłużnej E i poprzecznej G zaobserwowaną w czasie 72 godzin. Wskazuje to na osłabienie zamocowania włókien w lepko sprężystej matrycy po długim czasie eksploatacji konstrukcji i powoduje wzrost przemieszczenia poprzecznego.
The paper discusses some historical solutions of wooden structures used in order to reduce the impact of shear forces. A model of wood as a natural fibrous composite, built of fibres located in a visco-elastic matrix, was presented. The testing on support models made of wood was described in order to show the trend of variations of deflections and that of the reduction in the value of moduli of longitudinal elasticity E and shear moduli G surveyed during 72 hours. The trend demonstrated evidences a weakening of the fastening of fibres in the visco-elastic matrix during the operation of the wooden structure, also an increase in shear forces leading to the reduction in the global load capacity of an element or a system made of wood.
Źródło:
Dziedzictwo architektoniczne. Ochrona i badania obiektów zabytkowych; 17-25
9788374931519
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-25 z 27

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