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Abstrakt

In the article we study a model of TCP connection with Active Queue Managementin an intermediate IP router. We use the fluid flow approximation technique to model the interactions between the set of TCP flows and AQM algoithms. Computations for fluid flow approximation model are performed in the CUDA environment.
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In the article we study a model of network transmissions with Active Queue Management in an intermediate IP router. We use the OMNET++ discrete event simulator to model the varies variants of the CHOKe algoithms. We model a system where CHOKe, xCHOKe and gCHOKe are the AQM policy. The obtained results shows the behaviour of these algorithms. The paper presents also the implementation of AQM mechanisms in the router based on Linux.
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This paper presents non-linear mathematical model of a computer network with a part of wireless network. The article contains an analysis of the stability of the network based on TCP-DCR, which is a modification of the traditional TCP. Block diagram of the network model was converted to a form in order to investigate the D-stability using the method of the space of uncertain parameters. Robust D-stability is calculated for constant delays values.
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Human brain is “the perfect guessing machine” (James V. Stone (2012) Vision and Brain, Cambridge, Mass: The MIT Press, p. 155), trying to interpret sensory data in the light of previous biases or beliefs. Bayesian inference is carried out by three complex networks of the human brain: salience network, central executive network, and default mode network. Their function is analysed both in neurotypical person and Attention Deficit Disorder. Modern human being having predictive brain and overloaded mind must develop social identity, whose evolution went probably through three stages: social selection based on punishment, sexual selection based on reputation, and group selection based on identity.
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The article refers to the idea of using the software defined network (SDN) as an effective hardware and software platform enabling the creation and dynamic management of distributed ICT infrastructure supporting the rapid prototyping process. The authors proposed a new layered reference model remote distributed rapid prototyping that allows the development of heterogeneous, open systems of rapid prototyping in a distributed environment. Next, the implementation of this model was presented in which the functioning of the bottom layers of the model is based on the SDN architecture. Laboratory tests were carried out for this implementation which allowed to verify the proposed model in the real environment, as well as determine its potential and possibilities for further development. Thus, the approach described in the paper may contribute to the development and improvement of the efficiency of rapid prototyping processes which individual components are located in remote industrial, research and development units. Thanks to this, it will be possible to better integrate production processes as well as optimize the costs associated with prototyping. The proposed solution is also a response in this regard to the needs of industry 4.0 in the area of creating scalable, controllable and reliable platforms.
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Abstrakt

Poziom sprzedaży danego dobra uzależniony jest w dużej mierze od sieci dystrybucji. Przestrzenna analiza dystrybucji umożliwia racjonalizację sieci sprzedaży, co podnosi efektywność i wydajność sprzedaży przedsiębiorstwa z bezpośrednim przełożeniem na wzrost zysków. Z pomocą przychodzą tu tak zwane analizy przestrzenne. W artykule przedstawiono analizę sieci autoryzowanych sprzedawców Polskiej Grupy Górniczej dla województwa opolskiego. Analiza została wykonana z wykorzystaniem narzędzi GIS (SIP). Celem przeprowadzonej analizy było zaprezentowanie możliwych do zastosowania narzędzi weryfikacji już istniejącej sieci dystrybucji, jej racjonalizacji, bądź też tworzenia nowych punktów sprzedaży. Przedstawione narzędzia należą do operacji GIS stosowanych do przetwarzania danych przechowywanych w zasobach Systemów Informacji Przestrzennej. Są to tak zwane narzędzia geoprocessingu, czyli geoprzetwarzania. W artykule zaprezentowano kilka analiz przestrzennych, których rezultatem jest wybór najlepszej lokalizacji punktu dystrybucji pod względem określonych kryteriów. Stosowane narzędzia to między innymi zapytanie przestrzenne intersect (iloczyn), suma. Posłużono się także geokodowaniem, utworzono tak zwany kartodiagram. Przedstawiona przykładowa analiza może zostać wykonana dla sieci autoryzowanych sprzedawców zarówno w skali jednego województwa, miasta, jak też obszaru całego kraju. Użyte narzędzia dają możliwość sprecyzowania grupy docelowych odbiorców, obszarów na jakich się oni znajdują, obszarów koncentracji potencjalnych odbiorców. Pozwalają tym samym na ulokowanie punktów sprzedaży na obszarach charakteryzujących się wysokim prawdopodobieństwem znalezienia nowych klientów, umożliwiają wybór lokalizacji, np. zapewniającej dostęp do dróg, transportu kolejowego, lokalizacji o odpowiedniej powierzchni, sąsiedztwie.
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Abstrakt

A gigantic amounts of data and information on molecules that constitute the very complex cell machinery have been collected, classified and stored in data banks. Although we posses enormous amount of knowledge about the properties and functions of thousands of molecular entities, we are still far from understanding how they do work in a living cell. It is clear now that these molecules (genes, proteins) are not autonomous, that there is no direct linear relation between genotype and phenotype, and that the majority of functions are carried and executed by concerted molecular activity, and that the majority of diseases are multifactorial. A basic property of the matter in a living cell (both normal and pathologic) is an interaction between variety of macromolecules, mainly proteins, genes (DNA) etc. In a process of self-organization they are able to form an active molecular biologic system – a complex, labile and dynamic network which integrity is secured by non-covalent bounds. In this essay some basic properties of network structure and the universal rules that govern them are described. Network or system biology is promising new research approach in biology and medicine.
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Rockburst is a common engineering geological hazard. In order to evaluate rockburst liability in kimberlite at an underground diamond mine, a method combining generalized regression neural networks (GRNN) and fruit fly optimization algorithm (FOA) is employed. Based on two fundamental premises of rockburst occurrence, depth, σθ, σc, σt, B1, B2, SCF, Wet are determined as indicators of rockburst, which are also input vectors of GRNN model. 132 groups of data obtained from rockburst cases from all over the world are chosen as training samples to train the GRNN model; FOA is used to seek the optimal parameter σ that generates the most accurate GRNN model. The trained GRNN model is adopted to evaluate burst liability in kimberlite pipes. The same eight rockburst indicators are acquired from lab tests, mine site and FEM model as test sample features. Evaluation results made by GRNN can be confirmed by a rockburst case at this mine. GRNN do not require any prior knowledge about the nature of the relationship between the input and output variables and avoid analyzing the mechanism of rockburst, which has a bright prospect for engineering rockburst potential evaluation.
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Abstrakt

AbstractThe stability of fractional standard and positive continuous-time linear systems with state matrices in integer and rational powers is addressed. It is shown that the fractional systems are asymptotically stable if and only if the eigenvalues of the state matrices satisfy some conditions imposed on the phases of the eigenvalues. The fractional standard systems are unstable if the state matrices have at least one positive eigenvalue.
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AbstractThe classical Cayley-Hamilton theorem is extended to Drazin inverse matrices and to standard inverse matrices. It is shown that knowing the characteristic polynomial of the singular matrix or nonsingular matrix, it is possible to write the analog Cayley-Hamilton equations for Drazin inverse matrix and for standard inverse matrices.
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AbstractThe Caputo-Fabrizio definition of the fractional derivative is applied to minimum energy control of fractional positive continuous- time linear systems with bounded inputs. Conditions for the reachability of standard and positive fractional linear continuous-time systems are established. The minimum energy control problem for the fractional positive linear systems with bounded inputs is formulated and solved.
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Abstrakt

AbstractThis paper describes a new method of determining the reactive power factor. The reactive power factor herein is calculated on the basis of time samples and not] with the Fourier transform of signals, like it was done previously. The new reactive power factor calculation results from the receiver admittance-operator decomposition into the product of self-adjoint and unitary operators. This is an alternative decomposition to another one, namely into a sum of the Hermitian and skew-Hemiitian operators.
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AbstractThe paper presents the problem of estimating in-situ compressive strength of concrete in a comprehensive way, taking into account the possibility of direct tests of cored specimens and indirect methods of non-destructive tests: rebound hammer tests and ultrasonic pulse velocity measurements. The paper approaches the discussed problem in an original, scientifically documented and exhaustive way, in particular in terms of application.
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AbstractPositive descriptor fractional discrete-time linear systems with fractional different orders are addressed in the paper. The decomposition of the regular pencil is used to extend necessary and sufficient conditions for positivity of the descriptor fractional discrete-time linear system with different fractional orders. A method for finding the decentralized controller for the class of positive systems is proposed and its effectiveness is demonstrated on a numerical example.
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Abstrakt

AbstractThis 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.
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Abstrakt

Polska w ostatniej dekadzie stała się jednym z najbardziej aktywnych rynków poszukiwania niekonwencjonalnych złóż węglowodorów. Obecnie na terenie kraju obowiązuje 20 koncesji na poszukiwanie i/lub rozpoznawanie złóż, w tym gazu z łupków. Powierzchnia objęta koncesjami poszukiwawczymi to 7,5% powierzchni kraju. W cyklu życia projektu zagospodarowania i eksploatacji gazu z zasobów łupkowych można wyróżnić cztery główne etapy: wybór i przygotowanie miejsca wykonania odwiertów, etap wiercenia i szczelinowania hydraulicznego, eksploatacja (produkcja) i marketing oraz „wygaszenie” eksploatacji i rekultywacja terenu. W artykule przedstawiono koncepcję analizy kosztów projektu inwestycyjnego związanego z poszukiwaniem i zagospodarowaniem złoża/obszaru gazu z łupków. Poddano analizie dwa pierwsze etapy dotyczące prac przygotowawczych, realizowanych na wybranym placu oraz prac wiertniczych i szczelinowania hydraulicznego. Ze względów ekonomicznych jedynym racjonalnym sposobem udostępnienia złóż gazu łupkowego jest stosowanie otworów poziomych, wykonywanych pojedynczo lub grupowo. Ilość padów wiertniczych, pokrywających obszar koncesji jest podstawowym determinantem kosztów zagospodarowania złoża. W artykule przedstawiono wyniki analizy kosztów różnego rodzaju sposobu rozwiercania złoża o powierzchni 25 000 000 m2. Oszacowań kosztów dokonano dla dwóch wariantów: grupowego wiercenia dla trzech rodzajów padów wiertniczych − z trzema, pięcioma i siedmioma otworami oraz dla otworów wykonywanych pojedynczo. Wyniki analizy pokazują, że wraz ze wzrostem liczby odwiertów w padzie maleją sumaryczne koszty rozwiercania złoża o założonej powierzchni. Dla padów z trzema odwiertami są mniejsze w stosunku do wariantu drugiego o ponad 7%, przy pięciu są mniejsze o 11%, a przy siedmiu odwiertach realizowanych z jednego placu budowy są mniejsze w stosunku do wariantu drugiego o 11,5%. Autorzy poprzez zastosowaną metodykę wskazują kierunek oraz sposoby dalszych badań i analiz, które umożliwią optymalizację prac wiertniczych na złożach gazu z łupków.
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Abstrakt

This article analyses a hierarchical structure of academia within two academic social media networking sites, i.e. Academia.edu and ResearchGate. In this study, I investigate profiles (in these two services) of all academic staff members of Adam Mickiewicz University in Poznań (N = 2661). I use the concept of prestige to analyse whether the hierarchical structure of academia is being reproduced in analysed services. Since prestige is an unobservable construct, I use two indicators to measure it: the number of followers and the number of views. My findings show that the hierarchical structure differs between Academia.edu and Research- Gate. While the structure of ResearchGate is explicitly hierarchical in reference to degrees of the researchers (a higher degree is related to a higher value of the prestige indicators), the structure of Academia.edu resembles a reversed pyramid (a higher degree is related to a lower value of the prestige indicators). The article concludes with a discussion concerning possible causes of differences between services in terms of reproducing the hierarchical structure. Moreover, I provide potential implications of the results as well as the justification of the necessity of using the concept of prestige to determine hierarchical structure of academia.
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Abstrakt

Mining ventilation should ensure in the excavations required amount of air on the basis of determined regulations and to mitigate various hazards. These excavations are mainly: longwalls, function chambers and headings. Considering the financial aspect, the costs of air distribution should be as low as possible and due to mentioned above issues the optimal air distribution should be taken into account including the workers safety and minimization of the total output power of main ventilation fans. The optimal air distribution is when the airflow rate in the mining areas and functional chambers are suitable to the existing hazards, and the total output power of the main fans is at a minimal but sufficient rate. Restructuring of mining sector in Poland is usually connected with the connection of different mines. Hence, dependent air streams (dependent air stream flows through a branch which links two intake air streams or two return air streams) exist in ventilation networks of connected mines. The zones of intake air and return air include these air streams. There are also particular air streams in the networks which connect subnetworks of main ventilation fans. They enable to direct return air to specified fans and to obtain different airflows in return zone. The new method of decreasing the costs of ventilation is presented in the article. The method allows to determine the optimal parameters of main ventilation fans (fan pressure and air quantity) and optimal air distribution can be achieved as a result. Then the total output power of the fans is the lowest which makes the reduction of costs of mine ventilation. The new method was applied for selected ventilation network. For positive regulation (by means of the stoppings) the optimal air distribution was achieved when the total output power of the fans was 253.311 kW and for most energy-intensive air distribution it was 409.893 kW. The difference between these cases showed the difference in annual energy consumption which was 1 714 MWh what was related to annual costs of fan work equaled 245 102 Euro. Similar values for negative regulation (by means of auxiliary fans) were: the total output power of the fans 203.359 kW (optimal condition) and 362.405 kW (most energy-intensive condition). The difference of annual energy consumption was 1 742 MWh and annual difference of costs was 249 106 Euro. The differences between optimal airflows considering positive and negative regulations were: the total output power of fans 49.952 kW, annual energy consumption 547 MWh, annual costs 78 217 Euro.
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Abstrakt

Wzmocnienie potencjału badawczego i transferu wiedzy z instytutów badawczych do przedsiębiorstw jest jednym z celów utworzenia Sieci Badawczej: Łukasiewicz. W artykule przedstawiono wyniki analizy potencjału badawczego 38 instytutów badawczych, które mają znaleźć się w SBŁ w oparciu o dane dotyczące publikacji naukowych z lat 2013–2016. Liczba publikacji instytutów SBŁ była zbliżona do liczby publikacji instytutów TNO i VTT, ale mniejsza niż instytutów Fraunhofer. Publikacje instytutów SBŁ miały niższe wartości wskaźników współpracy międzynarodowej oraz współpracy z biznesem, a także wskaźników cytowalności. Współautorzy publikacji SBŁ pochodzili głównie z krajowych jednostek naukowych, zaś współautorstwo z instytutami Fraunhofera, TNO i VTT miało charakter marginalny. W artykule przedstawiono także ograniczenia i wyzwania przyjętej metody badawczej oraz przyszłe kierunki badań w tym zakresie.
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The article summarizes panel discussions led at the Polish Scientific Networks conference. It covers the topics of social and (un)social innovations, their sources, and applications, as well as the new approaches to the concept of the wisdom of the crowds (as opposed to swarm mentality). The article draws on academic research on trust and distrust, declining reliance on formal expertise and a turn against the science, and posttruth society phenomenon. The article concludes with observations about risk aversion in different cultures, to suggest some practical solutions in education programs, needed to address the challenges of the future.
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The petrographic composition of coal has a significant impact on its technological and sorption properties. That composition is most frequently determined by means of microscope quantitative analyses. Thus, aside from the purely scientific aspect, such measurements have an important practical application in the industrial usage of coal, as well as in issues related to the safety in underground mining facilities. The article discusses research aiming at analyzing the usefulness of selected parameters of a digital image description in the process of automatic identification of macerals of the inertinite group using neural networks. The description of the investigated images was based on statistical parameters determined on the basis of a histogram and co-occurrence matrix (Haralick parameters). Each of the studied macerals was described by means of a 20-element feature vector. An analysis of its principal components (PCA) was conducted, along with establishing the relationship between the number of the applied components and the effectiveness of the MLP network. Based on that, the optimum number of input variables for the investigated classification task was chosen, which resulted in reduction of the size of the network’s hidden layer. As part of the discussed research, the authors also analyzed the process of classification of macerals of the inertinite group using an algorithm based on a group of MLP networks, where each network possessed one output. As a result, average recognition effectiveness of 80.9% was obtained for a single MLP network, and of 93.6% for a group of neural networks. The obtained results indicate that it is possible to use the proposed methodology as a tool supporting microscopic analyses of coal.
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