Wyniki wyszukiwania dla: TURBO CODES - MOST Wiedzy

Wyszukiwarka

Wyniki wyszukiwania dla: TURBO CODES

Filtry

wszystkich: 21685
wybranych: 1206

wyczyść wszystkie filtry


Filtry wybranego katalogu

  • Kategoria

  • Rok

  • Opcje

wyczyść Filtry wybranego katalogu niedostępne

Wyniki wyszukiwania dla: TURBO CODES

  • Ocena pracy dźwigara zadaszenia Hali Blanika w Gdańsku

    Wartykule przedstawiono kompleksowe sprawdzenie nośności stalowej konstrukcji zadaszenia Hali Leszka Blanika w Gdańsku. Dokonano oceny wpływu otworów dużej średnicy w środnikach dźwigara na jego nośność. Oszacowano nośność nietypowego, zginanego styku doczołowego łączącego elementy dwuteowe klasy 4. Obliczenia wykonano na podstawie norm i analiz modeli MES.

    Pełny tekst do pobrania w portalu

  • Drawing maps with advice

    Publikacja

    W pracy podejmujemy temat konstrukcji algorytmu dla agenta, który zostaje umieszczony w dowolnym wierzchołku grafu (wierzchołki są nierozróżnialne, krawędzie mają etykiety portów), po czym realizuje algorytm zmierzający do znalezienia drzewa spinającego grafu lub izomorficznej kopii grafu. Dla obu problemów podajemy asymptotycznie dokładne lub prawie dokładne oszacowania na ilość bitów dodatkowej informacji, którą agent musi otrzymać...

    Pełny tekst do pobrania w serwisie zewnętrznym

  • Power enhancement of the Brayton cycle by steam utilization

    Publikacja
    • K. Jesionek
    • A. Chrzczonowski
    • P. Ziółkowski
    • J. Badur

    - Archives of Thermodynamics - Rok 2012

    The paper presents thermodynamic analysis of the gas-steam unit of the 65 MWe combined heat and power station. Numerical analyses of the station was performed for the nominal operation conditions determining the Brayton and combined cycle. Furthermore, steam utilization for the gas turbine propulsion in the Cheng cycle was analysed. In the considered modernization, steam generated in the heat recovery steam generator unit is directed...

    Pełny tekst do pobrania w portalu

  • Numerical Studies on Propellers in Open Water and behind Hulls aiming to support the Evaluation of Propulsion Tests

    Publikacja
    • H. Streckwall
    • T. Lucke
    • T. Bugalski
    • J. Felicjancik
    • T. Goedicke
    • L. Greitsch
    • A. Talay
    • M. Alvar

    - Rok 2016

    A RANS based numerical analysis of propellers can contribute considerably to our understanding of propeller/hull interaction. It may also allow for a review of scaling procedures on results from experimental fluid dynamics (EFD). Using various RANS codes (Fluent, CFX, STAR-CCM+ and FreSCo+) on common test cases the authors first focused on propeller open water (POW) calculations. Next we simulated the propeller hull interaction...

    Pełny tekst do pobrania w serwisie zewnętrznym

  • On Configurability of Distributed Volunteer-Based Computing in the Comcute System

    Publikacja

    - Rok 2012

    The chapter proposes additional solutions that can be implemented within the Comcute system to increase its configurability. This refers to configuration of the reliability level in the W and S server layers, static or on-the-fly data partitioning and integration, configuration of the system for processing in the data streaming fashion, extending the system for selection of a project that the client wants to contribute to, ease...

  • Software Tools to Measure the Duplication of Information

    Data stored in average computer system usually is not unique, portions of stored data are duplicated. When duplicated data are stored in separate files containing source code of computer program of student homework, a possibility of cheating should be seriously considered. This paper presents software tools built, in order to detect re-use of pieces of code in supplied text files. Three aspects of information atching are considered:...

    Pełny tekst do pobrania w serwisie zewnętrznym

  • On the internal efficiency of a turbine stage: classical and CFD definitions

    Publikacja

    - Transactions of the Institute of Fluid-Flow Machinery - Rok 2012

    Almost entire fleet of steam turbines in Poland was designed between 1950 – 1980 with the use of the so-called zero dimensional (0D) calculation tools. For several years, design and modernization of the turbines occur in assistance with the state of the art methods that describe working fluid flow field based on 3D models and CFD codes. This cooperation between 0D and 3D codes requires exchange of overall, integral information...

  • Reinforced Secure Gossiping Against DoS Attacks in Post-Disaster Scenarios

    Publikacja

    - IEEE Access - Rok 2020

    During and after a disaster, the perceived quality of communication networks often becomes remarkably degraded with an increased ratio of packet losses due to physical damages of the networking equipment, disturbance to the radio frequency signals, continuous reconfiguration of the routing tables, or sudden spikes of the network traffic, e.g., caused by the increased user activity in a post-disaster period. Several techniques have...

    Pełny tekst do pobrania w portalu

  • INVESTIGATIONS OF THE EMISSION CHARACTERISTICS OF A DUAL-FUEL GAS TURBINE COMBUSTION CHAMBER OPERATING SIMULTANEOUSLY ON LIQUID AND GASEOUS FUELS

    Publikacja

    - Polish Maritime Research - Rok 2021

    T his study is dedicated to investigations of the working process in a dual-fuel low-emission combustion chamber for a floating vessel’s gas turbine. As the object of the research, a low-emission gas turbine combustion chamber with partial premixing of fuel and air inside the outer and inner radial-axial swirls was chosen. The method of the research is based on the numerical solution of the system of differential...

    Pełny tekst do pobrania w portalu

  • Architektura bezpieczeństwa systemu netBaltic

    W artykule zaprezentowano założenia dotyczące zabezpieczania węzłów sieci realizowanej w ramach systemu netBaltic. Ze względu na dużą różnorodność rozważanych mechanizmów komunikacyjnych architektura bezpieczeństwa została podzielona na kilka elementów – infrastrukturę klucza publicznego (PKI), bezpieczeństwo systemowe węzłów, zabezpieczanie komunikacji w modelu samoorganizującej wieloskokowej sieci kratowej, a także sieci niewrażliwej...

  • Artificial intelligence for software development — the present and the challenges for the future

    Since the time when first CASE (Computer-Aided Software Engineering) methods and tools were developed, little has been done in the area of automated creation of code. CASE tools support a software engineer in creation the system structure, in defining interfaces and relationships between software modules and, after the code has been written, in performing testing tasks on different levels of detail. Writing code is still the task...

    Pełny tekst do pobrania w portalu

  • Determining QoS in the Video Telephony Service in an IP Environment

    Publikacja

    - LECTURE NOTES IN COMPUTER SCIENCE - Rok 2010

    IP networks are indispensable nowadays. They are among the most efficient platforms. The constantly growing number of users and new services in these networks - the largest being the Internet - requires a good quality of any application used.Determining the QoS in real-time services is particularly important. This work is dedicated to exactly this aspect of the real-time service Video Telephony over IP (VToIP). First, the ITU-T...

  • generation of the vorticity mode by sound in a bingham plastic

    This study investigates interaction between acoustic and non-acoustic modes, such as vorticity mode,in some class of a non-newtonian fluid called Bingham plastic. The instantaneous equations describinginteraction between different modes are derived. The attention is paid to the nonlinear effects in the fieldof intense sound. The resulting equations which describe dynamics of both sound and the vorticity modeapply to both periodic...

    Pełny tekst do pobrania w portalu

  • Open-Source Coprocessor for Integer Multiple Precision Arithmetic

    Publikacja

    - Electronics - Rok 2020

    This paper presents an open-source digital circuit of the coprocessor for an integer multiple-precision arithmetic (MPA). The purpose of this coprocessor is to support a central processing unit (CPU) by offloading computations requiring integer precision higher than 32/64 bits. The coprocessor is developed using the very high speed integrated circuit hardware description language (VHDL) as an intellectual property (IP) core. Therefore,...

    Pełny tekst do pobrania w portalu

  • Local Texture Pattern Selection for Efficient Face Recognition and Tracking

    This paper describes the research aimed at finding the optimal configuration of the face recognition algorithm based on local texture descriptors (binary and ternary patterns). Since the identification module was supposed to be a part of the face tracking system developed for interactive wearable computer, proper feature selection, allowing for real-time operation, became particularly important. Our experiments showed that it is...

    Pełny tekst do pobrania w serwisie zewnętrznym

  • Reconstruction of 3D structure of positive corona streamer by local methods

    Publikacja
    • M. Kocik
    • M. Tański
    • J. Mizeraczyk
    • R. Ichiki
    • S. Kanazawa
    • J. Dembski

    - Rok 2009

    The computer algorithms were used for reconstruction of streamer 3D structure. We propose the 3D tree structure model of corona discharge streamer composed with nodes and edges between chosen couples of nodes, which enables easy computation of some important parameters ofstreamers. The 3D model can be derived directly from two projection images by global methods like evolutionary searching or particle simulations. In this paper...

    Pełny tekst do pobrania w serwisie zewnętrznym

  • Forced vibrations in a dynamic system that is damped by a mechanism that trans-pass through its singular position

    Publikacja

    - Rok 2017

    In the paper, vibrations of a hybrid multibody-continuous system are investigated. For all the mechanical devices, effective damping methods are crucial in the design process. To obtain it, installation of viscous dampers or elasto-viscous elements is dominant. In the paper, an alternative method is investigated. It is based on modal disparity. To describe the method briefly, when structural damping is present in continuous systems,...

  • Badanie jakości transmisji w interfejsie radiowym MC-CDMA

    Technika MC-CDMA (ang. Multi-Carrier Code Division Multiple Access) powstała z połączenia dwóch wcześniej stosowanych technik dostępu radiowego: CDMA (ang. Code Division Multiple Access) i OFDM (ang. Orthogonal Frequency-Division Multiplexing) i posiada zalety obu tych technologii. W referacie przedstawiona została budowa nadajnika i odbiornika dla tego interfejsu radiowego oraz wyniki badań symulacyjnych jakości transmisji w tym...

  • Multi-core processing system for real-time image processing in embedded computer vision applications

    Publikacja

    W artykule opisano architekturę wielordzeniowego programowalnego systemu do przetwarzania obrazów w czasie rzeczywistym. Dane obrazu są przetwarzane równocześnie przez wszystkie procesory. System umożliwia niskopoziomowe przetwarzanie obrazów,np. odejmowanie tła, wykrywanie obiektów ruchomych, transformacje geometryczne, indeksowanie wykrytych obiektów, ocena ich kształtu oraz podstawowa analiza trajektorii ruchu. Ang:This paper...

  • Context sensitive privacy management in a distributed environment

    Artykuł przedstawia mechanizm zarządzania prywatnością stworzony dla systemu rozproszonego z założeniem, że węzły systemu mają ograniczone zasoby (moc procesora, pamięć). Podstawowy pomysł zakłada, że prywatne dane są filtrowane zgodnie z polityką prywatności użytkowników przed ich ujawnieniem innym użytkownikom. Te decyzje są silnie umiejscowione, co ogranicza narzut związany z zarządzaniem prywatnością na węzłach systemu. Sam...

    Pełny tekst do pobrania w serwisie zewnętrznym

  • On-line Search in Two-Dimensional Environment

    We consider the following on-line pursuit-evasion problem. A team of mobile agents called searchers starts at an arbitrary node of an unknown network. Their goal is to execute a search strategy that guarantees capturing a fast and invisible intruder regardless of its movements using as few searchers as possible. We require that the strategy is connected and monotone, that is, at each point of the execution the part of the graph...

    Pełny tekst do pobrania w portalu

  • Arc-length Algorithm Efficiency in the Analysis of Thermally Loaded Multilayered Shells

    Publikacja

    This paper concerns the efficiency study of the arc-length algorithm in the geometrically non-linear analysis of thermally loaded multilayered shells. The thermal loading is considered as the one-way thermo-mechanical coupling effect. Two implementations of the arc-length method are examined: the path-following technique available in NX-Nastran and the RiksWempner-Ramm algorithm adopted in the authors’ computer code SHLTH. It is...

    Pełny tekst do pobrania w portalu

  • The reliability of tree and star networks

    This paper investigated the reliability of tree and star networks. Following measures of network reliability are assumed: the expected number of nodes, that can communicate with the central node; the expected number of node pairs, that are connected by a path through the central node; the expected number of node pairs communicating.

    Pełny tekst do pobrania w serwisie zewnętrznym

  • GENERALISED HERSCHEL MODEL APPLIED TO BLOOD FLOW MODELLING

    Publikacja

    - TASK Quarterly - Rok 2012

    This paper introduces a new rheological model of blood as a certain generalisation of the standard Herschel-Bulkley model. This model is a rheological constitutive equation and belongs to the group of the so-called generalised Newtonian fluids. Experimental data is compared with results, obtained from the new model, to demonstrate that it allows for the best agreement together with Luo-Kuang model. The new model may be easily implemented...

    Pełny tekst do pobrania w portalu

  • Safety-based approach in multifunctional building design

    Publikacja

    ABSTRACT: The modern trend in design of the public buildings is to create multifunctional environments in one building, hosting a variety of functions. Multifunctional buildings entertain large number of visitors. The complexity and vulnerability of this type of public space are the main reasons to use within their design process the performance based approach including the recognition of hazards. Safety and reliability approach...

  • New Method for Increasing Precision of Position Estimation of a Moving Person in Hybrid Inertial Navigation System

    Publikacja

    In this article a new method for increasing precision of position estimation of inertial navigation in hybrid localization system with reduced number of reference nodes for radio distance measurements is presented. Measuring tests were carried out to verify precision of position estimation of moving person in indoor environment.

  • Wireless Systems of Threats Monitoring

    Concept of wireless system of threats monitoring with self-organizing network of multipurpose data transfer nodes are presented. Two practical applications of this system are also presented. The first of these is the Global Wireless Monitoring System for Containers and the second is the Mobile Monitoring System for Gas Air Pollution Measurements.

  • Wireless systems of threats monitoring

    The concept of wireless system of threats monitoring with self-organizing network of multipurpose data transfer nodes are presented. Two practical applications of this system are also presented. The first of these is the Global Wireless Monitoring System for Containers, and the second is the Mobile Monitoring System for Gas Air Pollution Measurements.

  • Wireless systems of threats monitoring

    The concept of wireless system of threats monitoring with self-organizing network of multipurpose data transfer nodes are presented. Two practical applications of this system are also presented. The first of these is the Global Wireless Monitoring System for Containers, and the second is the Mobile Monitoring System for Gas Air Pollution Measurements.

  • Introducing a Computational Method to Retrofit Damaged Buildings under Seismic Mainshock-Aftershock Sequence

    Retrofitting damaged buildings is a challenge for engineers, since commercial software does not have the ability to consider the local damages and deformed shape of a building resulting from the mainshock record of an earthquake before applying the aftershock record. In this research, a computational method for retrofitting of damaged buildings under seismic mainshock-aftershock sequences is proposed, and proposed computational...

    Pełny tekst do pobrania w portalu

  • Collision-free network exploration

    Publikacja
    • J. Czyzowicz
    • D. Dereniowski
    • L. Gąsieniec
    • R. Klasing
    • A. Kosowski
    • D. Pająk

    - JOURNAL OF COMPUTER AND SYSTEM SCIENCES - Rok 2017

    Mobile agents start at different nodes of an n-node network. The agents synchronously move along the network edges in a collision-free way, i.e., in no round two agents may occupy the same node. An agent has no knowledge of the number and initial positions of other agents. We are looking for the shortest time required to reach a configuration in which each agent has visited all nodes and returned to its starting location. In...

    Pełny tekst do pobrania w portalu

  • Distributed protection against non-cooperative node behavior in multi-hop wireless networks

    Publikacja

    An important security problem in today's distributed data networks is the prevention of non-cooperative behavior i.e., attacks consisting in the modification of standard node operation to gain unfair advantage over other system nodes. Such a behavior is currently feasible in many types of computer networks whose communication protocols are designed to maximize the network performance assuming full node cooperation. Moreover, it...

  • Optical and chemical characterization of thin TiNx films deposited by DC-magnetron sputtering

    Publikacja

    - VACUUM - Rok 2008

    Thin titanium nitride (tinx) films were deposited on silicon substrates by means of a reactive dc-magnetron plasma. Layers were synthesized under various conditions of discharge power and nitrogen flows in two operation modes of the magnetron (the so-called "balanced" and "unbalanced" modes). The optical constants of the tinx films were investigated by spectroscopic ellipsometry (se). X-ray photoelectron spectroscopy (xps) was...

    Pełny tekst do pobrania w serwisie zewnętrznym

  • A METHOD OF TRUST MANAGEMENT IN WIRELESS SENSOR NETWORKS

    The research problem considered in this paper is how to protect wireless sensor networks (WSN) against cyber-threats by applying trust management and how to strengthen network resilience to attacks targeting the trust management mechanism itself. A new method, called WSN Cooperative Trust Management Method (WCT2M), of distributed trust management in multi-layer wireless sensor networks is proposed and its performance is evaluated....

    Pełny tekst do pobrania w serwisie zewnętrznym

  • Increase of power and efficiency of the 900 MW supercritical power plant through incorporation of the ORC

    Publikacja

    - Archives of Thermodynamics - Rok 2013

    The objective of the paper is to analyse thermodynamical and operational parameters of the supercritical power plant with reference conditions as well as following the introduction of the hybrid system incorporating ORC. In ORC the upper heat source is a stream of hot water from the system of heat recovery having temperature of 90 °C, which is additionally aided by heat from the bleeds of the steam turbine. Thermodynamical analysis...

    Pełny tekst do pobrania w portalu

  • Synchronous black hole search in directed graphs

    Publikacja

    - THEORETICAL COMPUTER SCIENCE - Rok 2011

    The paper considers a team of robots which has to explore a graph G, where some nodes can be harmful. Robots are initially located at the so-called home base node. The dangerous nodes are the so-called black hole nodes, and once a robot enters in one of them, it is destroyed. The goal is to find a strategy in order to explore G in such a way that minimum number of robots is wasted. The exploration ends if there is at least one...

    Pełny tekst do pobrania w portalu

  • Dedukcja zachowań węzłów sieci ad hoc na podstawie potwierdzeń końcowych: ocena dokładności

    Przebadano precyzję algorytmu dedukcji rzeczywistych spolegliwości węzłów sieci MANET w oparciu o potwierdzenia end-to-end i bez użycia mechanizmu watchdog. W przeprowadzonych eksperymentach numerycznych wskazano charakterystyki topologiczne wpływające na tę precyzję.

  • Low-Loss 3D-Printed Waveguide Filters Based on Deformed Dual-Mode Cavity Resonators

    Publikacja

    This paper introduces a new type of waveguide filter with smooth profile, based on specially designed dual-mode (DM) cavity resonators. The DM cavity design is achieved by applying a shape deformation scheme. The coupling between the two orthogonal cavity modes is implemented by breaking the symmetry of the structure, thus eliminating the need for additional coupling elements. The modes operating in the cavity are carefully analyzed...

    Pełny tekst do pobrania w portalu

  • Localization in wireless sensor networks using switched parasitic antennas

    Publikacja

    A switched parasitic monopole antenna for 2.4 GHz ISM applications is design and investigated in this paper. One of the most promising applications for such switched-beam antennas is localization in wireless sensor networks (WSN). It is demonstrated that the use of this antenna improves accuracy of localization algorithms and allows for reduction of the number of reference nodes in localization system.

    Pełny tekst do pobrania w serwisie zewnętrznym

  • Towards β-selectivity in functional estrogen receptor antagonists

    Publikacja
    • J. J. Rodríguez
    • K. Filipiak
    • M. Maslyk
    • J. Ciepielski
    • S. Demkowicz
    • S. de Pascual-Teresa
    • S. Martín-Santamaría
    • B. d. P. ..
    • A. Ramos

    - ORGANIC & BIOMOLECULAR CHEMISTRY - Rok 2012

    Based on the benzo[b]naphtho[1,2-d]furan and benzo[b]naphtho[1,2-d]thiophene frameworks, a series of ligands with different basic side chains (BSCs) has been synthesized and pharmacologically evaluated. Also, their binding modes have been modelled using docking techniques. It was found that the introduction of a BSC in these systems brings about a decrease of affinity for both estrogen receptors α and β in an in vitro competitive...

    Pełny tekst do pobrania w portalu

  • “Green” nature of the process of derivatization in analytical sample preparation

    Publikacja

    Nowadays, the idea of Green Analytical Chemistry (GAC) is of high importance what impacts on the rapid growth in the sample preparation area with special emphasis on sample preparation simplification, miniaturization, and automation. Because the derivatization process is often an essential element of the analytical procedure, it should be important to focus on this issue from GAC perspective and conduct a series of experiments...

    Pełny tekst do pobrania w portalu

  • Collaborative Exploration of Trees by Energy-Constrained Mobile Robots

    Publikacja

    - THEORY OF COMPUTING SYSTEMS - Rok 2018

    We study the problem of exploration of a tree by mobile agents (robots) that have limited energy. The energy constraint bounds the number of edges that can be traversed by a single agent. We use a team of agents to collectively explore the tree and the objective is to minimize the size of this team. The agents start at a single node, the designated root of the tree and the height of the tree is assumed to be less than the energy...

    Pełny tekst do pobrania w serwisie zewnętrznym

  • Electron collisions with cyanoacetylene HC3N : Vibrational excitation and dissociative electron attachment

    Publikacja
    • M. Ranković
    • P. Nag
    • M. Zawadzki
    • L. Ballauf
    • J. Žabka
    • M. Polášek
    • J. Kočišek
    • J. Fedor

    - PHYSICAL REVIEW A - Rok 2018

    We experimentally probe electron collisions with HC3N in the energy range from 0 to 10 eV with the focus on vibrational excitation and dissociative electron attachment. The vibrational excitation cross sections show a number of resonances which are mode specific: the two dominant π∗ resonances are visible in the excitation of all the vibrational modes; however, broad σ ∗ resonances are visible only in certain bond-stretching vibrational...

    Pełny tekst do pobrania w portalu

  • New Method for Increasing Precision of Position Estimation in Hybrid Inertial Navigation System

    In article new method for increasing precision of position estimation by using inertial navigation in hybrid localization system with reduced number of reference nodes for radio distance measurements was presented. Measuring campaign using developed measuring stand were carried out to verify precision of position estimation of moving person in indoor environment.

  • Sensitivity analysis of critical forces of trusses with side bracing

    The present research is devoted to the study of out-of-plane buckling of trusses with elastic side bracing. Inthis paper, a sensitivity analysis of critical buckling loads of a truss due to bracing stiffness is carried out. A method based on the sensitivity analysis for the determination of the threshold bracing stiffness conditionfor full bracing of a truss is proposed. The influence lines of the unit change of the bracing stiffness...

    Pełny tekst do pobrania w serwisie zewnętrznym

  • Revalorization of the Szewalski binary vapour cycle

    Publikacja

    The aim of the paper is to revalorizate of the Szewalski binary vapour cycle by analysing thermodynamical and operational parameters of this cycle. This was carried by accessible numerical CFM (Computational Flow Mechanics) codes type, by step-by-step modeling of separates apparatus. The binary vapour cycle is providing steam as the working fluid in the high temperature part of the cycle, while another fluid - a low boiling point...

    Pełny tekst do pobrania w portalu

  • Using Continuous Integration Techniques in Open Source Projects – An Exploratory Study

    For a growing number of software projects, continuous integration (CI) techniques are becoming an essential part of the process. However, the maturity of their adoption in open source projects varies. In this paper, we present an empirical study on GitHub repositories to explore the use of continuous integration techniques in open source projects. Following the Goal-Question-Metric (GQM) approach, 3 research questions and 7 metrics...

    Pełny tekst do pobrania w portalu

  • MEASUREMENT OF NOISE IN SUPERCAPACITORS

    A developed method and measurement setup for measurement of noise generated in a supercapacitor is presented. The requirements for noise data recording are considered and correlated with working modes of supercapacitors. An example of results of low-frequency noise measurements in commercially available supercapacitors are presented. The ability of flicker noise measurements suggests that they can be used to assess quality of tested supercapacitors.

    Pełny tekst do pobrania w portalu

  • Structural response of existing spatial truss roof construction based on Cosserat rod theory

    Paper presents the application of the Cosserat rod theory and newly developed associated finite elements code as the tools that support in the expert-designing engineering practice. Mechanical principles of the 3D spatially curved rods, dynamics (statics) laws, principle of virtual work are discussed. Corresponding FEM approach with interpolation and accumulation techniques of state variables are shown that enable the formulation...

    Pełny tekst do pobrania w portalu

  • Controlled English Interface for Knowledge Bases

    This paper describes the approach to interface for OWL Knowledge Bases based on Controlled English that is transformed directly to OWL 2 expressions and back. Two possible modes enable usage of the interface to specify Terminology, World Description as well as Integrity Constrains. Knowledge Base then can be validated against the Integrity Constrains to enable its continuous validation.

    Pełny tekst do pobrania w portalu