Wyniki wyszukiwania - Biblioteka Nauki

1

Identification and formation of alliterations vs. the pre-school period and the model of reading education implemented in a nursery school

100%

Jaszczyszyn E.

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2009

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tom 03

EN

Child-friendly educational procedures consisting in the supporting a child in the mastering of the reading are implemented in two ways: a) an intermediate way (by “developing the readiness), and b) in an immediate way - by learning to read. Both types of actions should merge. Amongst factors determining success in the learning to read and write, P. Bryant and U. Goswami - authors of the casual theory of reading, indicate early-child-hood phonological skills, including: identification and formation of rhymes and alliterations (i.e. the capability to differentiate larger elements than a single sound, but smaller than syllables (rhymes and alliterations)). Child’s susceptibility to, among other things, alliterations results in advances in reading and writing in the subsequent education. A significant part of the reported study was devoted to models of reading education applied in the case of the six-year-olds examined. Ideas on how to “introduce children into the world of writing” are basically realized acc. to two models - a standard and a holistic one (see: Górniewicz, 1989; Arciszewska, 2002; Marzano, Paynter, 2004). In both models, children are provided conditions for developing their “readiness for reading” and “mastering the skill of reading”. The models differ in terms of organization and applied methods of the learning to read (Czerwińska, Narożnik, 1997; Doman, Doman, 1992; Majchrzak, 1995, 2007; Rocławski, 1998; Arciszewska, 2002). Both models involve the acquisition of prosodic elements of language (with various intensity). The presented fragment of a research was aimed at providing an answer to a question on the level of capabilities to identify and form alliterations displayed by the surveyed six-year-old children. In analyses, consideration was given to the number of years the children have been attending to a nursery school and the model of reading education realized therein.

2

Analiza pełnofalowa anteny skanującej na podłożu ferroelekrycznym

100%

Jaszczyszyn E.

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tom Vol. 50, z. 2

287-311

PL

W pracy przedstawiono koncepcję i opracowano nowy rodzaj skanującej anteny paskowej na podłożu ferroelektrycznym bez konieczności wykorzystania przesuwników fazy. Ponadto opracowano uogólnioną metodę analizy elektrodynamicznej rozpatrywanej struktury promieniującej wraz z metodą analizy numerycznej. Wyniki badań anteny skanującej wskazują na możliwość szerokiego jej zastosowania, a przedstawiona metoda analizy pełnofalowej do projektowania struktur promieniujących.

EN

Electronically scanned microwave antennas is accomplished by electronically altering the phase across the antenna radiating aperture (by means of discrete phase shifting elements or by changing frequency). This conventional inertialess scanning techniques in the microwave region are not cheap. A new scan antenna concept that realizable design using low-cost fabrication processes is presented. This concept is based on the first higher order mode on a microstrip line, which substrate is made using ceramic-polymer composite with modified ferroelectric powder Ba0,65Sr0,35TiO3 and appropriate polymer (grains of the powder have been sprayed into polymer with specific method). This ceramic-polymer composite was designed to change permittivity in response to an applied electric control field. The property of ferroelectric materials having a dielectric constant which can be modulated at high frequencies is very attractive. The feasibility of dielectric scanning (changing the direction of the beam by varying the relative permittivity of the electrically controlled ceramic-polymer composite) has been investigated. The radiation characteristics of such antenna have been accurate evaluated. Both longitudinal and transverse currents are treated. The method of solution used is an extension of the Fourier integral method which is used in conjunction with the method of moments (Galerkin solution). The propagation constant kx for higher order modes in open microstrip were calculated. In the present structure the complex propagation constant can be changed by changing the frequency or by changing the dielectric constant of the substrate (E2) as in the case of electrically controlled ferroelectric ceramic-polymer composite. In general, the direction of the radiated beam is given by Om = sin-1 (B), where kx (E2) = B(E2) = j * A(E2). For frequencies not far above the cut-off frequency, that means for B/k 0 < 1 (B in phase constant of the first higher order mode), the fields of the first higher order mode on the microstrip line are coupled to the line very loosely resulting in a considerable radiation.

3

Model kolejkowy dla analizy Sieci Inteligentnej

63%

Kryvinska N. , Jaszczyszyn E.

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tom Vol. 50, z. 1

25-32

PL

Wraz z wdrażaniem usług Sieci Inteligentnych (ang. Intelligent Network) pojawia się potrzeba oszacowania wydajności systemu w przypadku wykorzystania platformy z rozproszoną inteligencją. Przedstawiony artykuł omawia model kolejkowy dla analizy połączeń telefonicznych (wywołań) Sieci Inteligentnej. Sieć Inteligentna została przedstawiona w postaci sieci kolejkowej przy założeniu, że łączna liczba abonentów (tj. SSP) jest stała, co powoduje, że mamy zamkniętą sieć kolejkową. Rozproszoną architekturę Sieci Inteligentnej przedstawiono w postaci modelu kolejkowego ze źródłem skończonym - M/M/1/K/K. W artykule oszacowano czas oczekiwania odpowiedzi, oraz przedstawiono wyniki analizy i odpowiednie zależności.

EN

With increasing deployment of IN services, design and engineering of network intelligence platforms to accomodate the ever-changing and growing demands of customers, presents a rich market of opportunities and challenges. As telecommunications industry evolves, customers are increasingly coming expecting instantaneous acces to service providers, together with transparency to network failures. System performance dictates that response times need to be minimized, sufficient redundant capacity, to be installed in case of failure and controls embedded within the design to manage the exceptional situations that continually threaten network integrity. The service scenario mixes service demand, physical network topology, signaling message flows, the mapping of functional entities to physical components, and routing as part of the network design process. For the system performance aspect, the most significant changes due to intelligent network are the distribution of network intelligence and the new services made possible by this distributed architecture. In IN environment, a call involves the cooperative processing of several network elements connected by a signaling network. This fundamental change possesses some new challenges to teletraffic experts to ensure that IN network are designed to provide customer's services with good performance. This paper discusses a queuing system model for the performance analysis of IN call processing. The intelligent network is presented as a network of queues where the total number of customers (e.g., SSPs) is fixed, thus forming a closed queuing network. The In distributed architecture is modeled as a finite source queuing model -- M/M/1/K/K. The expected response time for that model is analyzed and computed. The numerical results and the corresponding curves are provided. And, related to open questions, future work is summarized.

4

Synteza paskowych szyków antenowych na podłożu ferroelektrycznym

63%

Jaszczyszyn E. , Modelski J.

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2002

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tom Vol. 48, z. 1

67-80

PL

W pracy przedstawiono nową metodę syntezy anten paskowych, przydatnych do zastosowań w systemach adaptacyjnych. Proponowana metoda polega na poszukiwaniu optymalnych kształtów charakterystyk promieniowania pojedynczych radiatorów w szyku antenowym (przez zmianę przenikalności elektrycznej podłoża ferroelektrycznego radiatora paskowego) bez konieczności stosowania przesuwników fazy i tłumików. W pracy przedstawione wyniki syntezy oraz porównanie proponowanej metody z ogólnie stosowanymi.

EN

ln modern radio system smart beamforming is often required. Communications antennas must offer a large number of operating modes (including pencil and shaped beams with fast switching between them) in order to ensure the best coverage of the service area. Therefore in designing smart antennas one of the main challenges is to provide a prescribed shaped antenna pattern that simultaneously suppresses interference signals (which locations are either known or unknown). As a rule this problem is solved with the use of phased-array antennas. This type of array consists of multiple stationary antenna elements which are fed coherently and use variable phase or time-delay control at each element to scan the beam to given angles in space. Variable amplitude control is sometimes also provided for pattern shaping. Performance of each radiating element bas significant influence on the parameters of antenna array, e.g. pattern, beamwidth, directivity gain, sidelobes, cross-polarization levels etc. Reducing the cost of phased array antennas has recently become the subject of considerable interest. The most prominent obstacle to this is the cost of current phase shifter elements (p-I-n diodes, MESFETs, ferrite). AIl of these are expensive, constituting a significant portion of the total receive-array cost. Additionally, p-I-n diodes and MESFETs introduce significant losses. These losses necessitate additional amplification of signal thus complicate the overall system design. New developments in MEMS and ferroelectric technologies promise low loss/high performance phase shifters. Both technologies provide low losses with beam capabilities, high isolation, good power handling ability, and low intermodulation distortion. Ferroelectrics are beneficial for applications operating at microwaves range, offering large phase shift per loss, low losses (0.2-0.3 dB, depending on frequency and matching), and large power handling capability. Bulk ferroelectric are beneficial for large phased array antennas because acceptable radiation characteristics may be achieved with fewer elements, lower cost, smaller size, and weight and lower power consumption. The design of a low-cost antenna array with 2D steering capability is very important for radiocommunication. As the satellite and mobile wireless communications technologies continue to utilize higher frequencies in the 20 to 60 GHz range, the design of a phased array antenna becomes prohibitively expensive. Also the realization od 2D scanning capability to track the satellite or to provide adequate urban communications systems becomes increasingly difficult to realize at a sufficiently low-cost suitable for the consumer market. The aim of this paper is to present a new method of array pattern synthesis by taking into consideration pattern of each radiator specially of the ferroelectric one. Radiating elements employing ferroelectric materials may give much better performance compared with ferrite ones, because of their high power handling capability, low drive power, full military temperature range of operation and low cost. The main feature of the ferroelectric antennas is the change of ferroelectric material permittivity with an applied dc control voltage. The permittivity change by varying the dc bias enables to create different radiation patterns. This permits to use such radiating element in several applications, e.g. smart antenna arrays. In this paper, new method of pattern synthesis of antenna arrays without phase shifters and attenuators has been presented. This concept is based on utilizing voltage-controlled ferroelectric array, where variable pattern of each antenna element is used to synthesize array pattrern.

5

Zastosowanie ultrakrótkich impulsów w mikrofalowym systemie obrazującym

51%

Bury M. , Kozłowski S. , Jaszczyszyn E.

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2008

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tom Vol. 49, nr 2

22-25

PL

Zaprezentowano model laboratoryjny mikrofalowego systemu obrazującego. System ten pozwala na uzyskanie przekroju poprzecznego obiektu umieszczonego na stole obrotowym i oświetlanego pod różnymi kątami ultrakrótkimi impulsami mikrofalowymi. Omówiono uproszczony model matematyczny systemu, wyniki symulacji komputerowych oraz wyniki pomiarów.

EN

The paper concerns a laboratory model of microwave imaging system. It allows obtaining the cross-section of the object under test located on a revolving platform and excited with ultra short microwave pulses. The cross-section is calculated on a base of raw measurement data matrix constituted by the received signals, reflected from the object under test for subsequent angle locations. Paper presents mathematical model of the system, the results of computer simulations as well as measurement results.

6

Badania właściwości materiałów ferroelektrycznych w zakresie mikrofal

51%

Jaszczyszyn E. , Szafran M. , Modelski J. , Bobryk E.

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tom Vol. 49, z. 2

247-256

PL

W pracy przedstawiono impulsową metodę do pomiaru parametrów materiałów ceramiczno-polimerowych, przydatnych do zastosowań w zakresie mikrofal. Przeprowadzono także badania kompozytowych warstw ceramiczno-polimerowych zawierających modyfikowany ceramiczny proszek ferroelektryczny typu Ba0.65Sr0.35TiO3 oraz odpowiedni polimer, w którym w sposób dyskretny rozproszone zostały ziarna tego proszku. Otrzymane współczynniki przestrajania skutecznej przenikalności elektrycznej pozwalają stwierdzić, że warstwy takie nadają się do opracowania nowych typów anten oraz podzespołów mikrofalowych.

EN

Pulse method for microwave measurement of the ceramic-polymer materials parameters has been developed. Ceramic-polymer composite substrates with modified ferroelectric powder Ba0.65Sr0.35TiO3 and appropriate polymer (grains of the powder have been sprayed into polymer with specific method) have been also investigated. The powder Ba0.65 Sr0.35TiO3 has been synthesized at the temperature range 1150-1350C/3h and admixture (from 0,5% to 3%) of oxides of nickel or manganese or iron have been added. The ferroelectric powder after being granulated (into grinder) according to desired size (1-5 um) has been utilized in order to obtain ceramic-polymer films. The substrates of the ceramic-polymer composite have been designed such that volume of the ferroelectric powder was from 75% to 97,5%. However, volume of the polymer was at the range from 2,5 to 25%. Thickness of the composite layer has been chosen from 100 to 500 um. The type of the polymer required for obtaining the composite with desired parameters has been also investigated. Main properties of the composite are mechanical resistance and flexibility. They permit to operate easy with obtained substrate and cover conductive plane with it. The polystyrene and polyvinyl butyral are the best among many investigated polymers. The proposed pulse method for microwave measurement of the ceramic-polymer materials parameters is based on measurement of the pulse delay to after pulse passed of the microstrip line fragment. The substrate of the microstrip line is realized with ferroelectric material. Utilizing this pulse method permits to accurately define the pulse delay without matched to microstrip, but it does not permit to assign losses. Because permittivities of the investigated materials are primarily unknown this way might be very useful. Microstrip line can be matched and the losses can be determined by changing pulse magnitudes. Obtained results (e.g. tuning ability coefficient of the effective permittivity) show that ceramic-polymer substrate can be utilized in designing new type of antennas and microwave devices.

7

Ceramic-polymer composites for microwave applications

45%

Szafran M. , Bogdańska B. , Bobryk E. , Jaszczyszyn E. , Derzakowski K.

Composites Theory and Practice

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2012

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tom R. 12, nr 1

9-13

EN

Ceramic-polymer composites with ferroelectric properties provide significant opportunities in the design and manufacture of modern electronic materials whose functional characteristics are constantly being improved. Barium titanate (BT) and barium strontium titanate (BST) are known and widely used materials in electronics. The paper presents the results of research on a receiving ceramic-polymer composite with an as low as possible permittivity and loss tangent. As a ceramic fraction barium-strontium titanate (BST) with various dopants (Fe2O3, Ni2O3, La2O3, SnO2 and Y2O3) were tested and as an organic one - water dispersions of styrene-acrylic polymers. The influence of BST doped with metal oxides on the sintering process was observed. X-ray diffraction patterns were made for sintered powders while the Vickers hardness, relative density and volume shrinkage of sintered pellets were studied. The zeta potential as a function of pH for pure BST and doped with Ni2O3 were measured. BST doped with Ni2O3 had the best relative density and this powder was used for further research. For the aqueous tape casting method four water dispersions of polymers with different concentrations and structures as binders were tested. For these polymers heat flow as a function of temperature by differential scanning calorimetry (DSC) and the glass transition temperature were measured. Additionally, the concentration of water dispersion of the polymers was tested by the gravimetric method. For the obtained ceramic - polymer composites, the relative permittivity and loss tangent were measured at a 9 GHz frequency.

PL

Kompozyty ceramiczno-polimerowe o właściwościach ferroelektrycznych dają znaczne możliwości przy projektowaniu i wytwarzaniu nowoczesnych materiałów elektronicznych o nowych i wciąż udoskonalanych cechach użytkowych. Znanym od lat i powszechnie stosowanym materiałem w elektronice jest tytanian baru (BT) oraz tytanian barowo-strontowy (BST). Domieszkowanie BST tlenkami metali powoduje zmianę parametrów elektrycznych (np. przenikalności dielektrycznej, tangensa kąta strat) oraz fizycznych (twardości, zagęszczenia). W niniejszej pracy badano wpływ domieszek (Fe2O3, Ni2O3, La2O3, SnO2 i Y2O3) na proces spiekania BST w zakresie 1200÷1400°C. Przeprowadzono analizę rentgenograficzną otrzymanych proszków, a także zbadano mikrotwardość Vickersa, względne zagęszczenie spieków oraz ich skurczliwość objętościową. Wykonano pomiary potencjału zeta w funkcji pH dla czystego BST oraz domieszkowanego 2 i 8% mol Ni2O3. Na podstawie otrzymanych wyników wybrano proszek o najlepszym zagęszczeniu (BST + 5% mol Ni2O3) i dobrano spoiwo polimerowe oraz upłynniacz, aby otrzymać gęstwę odpowiednią do odlania folii metodą aqueous tape casting. Istotne było dobranie polimerów obniżających lub niewpływających znacząco na wartość względnej przenikalności dielektrycznej, ponieważ po procesie formowania folia nie była już spiekana. Badano wodne dyspersje polimerów styrenowo-akrylowych o różnych stężeniach, które wyznaczono metodą wagową. Wykonano pomiary zmiany strumienia ciepła w funkcji temperatury metodą skaningowej kalorymetrii różnicowej (DSC) i na podstawie tej zależności wyznaczono temperaturę zeszklenia analizowanych polimerów. Uzyskane kompozyty ceramiczno-polimerowe o różnych zawartościach proszku ceramicznego (60 i 55%) oraz różnych ilościach domieszek (2, 5 i 8% mol) poddano badaniom względnej przenikalności dielektrycznej oraz tangensa kąta strat przy częstotliwości 9 GHz.