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Tytuł:
A Framework for Evaluation of Communication Bandwidth Market Models
Autorzy:
Stańczak, W.
Pałka, P.
Lubacz, J.
Toczyłowski, E.
Powiązania:
https://bibliotekanauki.pl/articles/309142.pdf
Data publikacji:
2010
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
auctions
bandwidth trading
resource allocation
Opis:
The article presents a method of analysis of market-based models for resource allocation in communication networks. It consists of several stages: classification of a market model, generation of input data, data adaptation to a tested model, test calculations and, finally, presentation and interpretation of results. A set of general criteria to assess various models has been proposed. Tests are run using dedicated computer applications, data is stored in open XML-based format originated in the multicommodity market model. Network topologies are derived from the SNDlib library.
Źródło:
Journal of Telecommunications and Information Technology; 2010, 2; 52-60
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An approximate necessary condition for the optimal bandwidth selector in kernel density estimation
Autorzy:
Gajek, L.
Lenic, A.
Powiązania:
https://bibliotekanauki.pl/articles/1340710.pdf
Data publikacji:
1993
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
bandwidth selection
kernel density estimation
resampling
Opis:
An approximate necessary condition for the optimal bandwidth choice is derived. This condition is used to construct an iterative bandwidth selector. The algorithm is based on resampling and step-wise fitting the bandwidth to the density estimator from the previous iteration. Examples show fast convergence of the algorithm to the bandwidth value which is surprisingly close to the optimal one no matter what is the initial knowledge on the unknown density.
Źródło:
Applicationes Mathematicae; 1993-1995, 22, 1; 123-138
1233-7234
Pojawia się w:
Applicationes Mathematicae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of bandwidth reservation algorithms in HIPERLAN/2
Autorzy:
Woźniak, J.
Janczak, T.
Machan, P.
Neubauer, W.
Powiązania:
https://bibliotekanauki.pl/articles/308243.pdf
Data publikacji:
2004
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
HIPERLAN/2
MAC
bandwidth allocation
QoS
Opis:
This paper focuses on performance of channel access methods in the HIPERLAN/2 standard. It discusses commonly used approaches to bandwidth allocation and presents a modified algorithm for effective bandwidth management based on pre-scheduled resource grants. Simulation results show that the new algorithm ensures much higher throughput compared to the standard method.
Źródło:
Journal of Telecommunications and Information Technology; 2004, 2; 54-60
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Model for Balancing Aggregated Communication Bandwidth Resources
Autorzy:
Pałka, P.
Kołtyś, K.
Toczyłowski, E.
Żółtowska, I.
Powiązania:
https://bibliotekanauki.pl/articles/309024.pdf
Data publikacji:
2009
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
aggregation
auctions
bandwidth market
multicommodity trade
Opis:
In this paper we present a multicommodity bandwidth exchange model for balancing aggregated communication bandwidth resources (BACBR) that allows us to aggregate similar offers. In this model offers submitted to sell (or buy) the same, similar, or equivalent network resources (or demands for end-to-end connections) are aggregated into single commodities. BACBR model is based on the balancing communication bandwidth trade (BCBT) model. It requires much less variables and constraints then original BCBT, however the outcomes need to be disaggregated. The general model for disaggregation is also given in the paper.
Źródło:
Journal of Telecommunications and Information Technology; 2009, 3; 43-49
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bandwidth broker extension for optimal resource management
Autorzy:
Sohail, S.
Jha, S.
Powiązania:
https://bibliotekanauki.pl/articles/307723.pdf
Data publikacji:
2003
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
bandwidth broker
per domain behavior
resources management
Opis:
Bandwidth broker (BB), resource manager of differentiated services domain cannot provide per domain behavior (PDB) attribute information to customers and neighboring domains at the time of service level agreement (SLA) negotiation. Extending BB's functionality to calculate PDB attributes can help it to negotiate SLAs dynamically and efficiently. Using current measurements or historic data about PDB attributes, bandwidth broker can perform off-line analysis to evaluate the range of quality of service (QoS) parameters that its domain can offer. Using these values BB can perform optimal capacity planning of the links and provide better QoS guarantees.
Źródło:
Journal of Telecommunications and Information Technology; 2003, 2; 77-82
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evolutionary Analysis of GSM, UMTS and LTE Mobile Network Architectures
Autorzy:
Ochang, Paschal A.
Irving, Philip J.
Powiązania:
https://bibliotekanauki.pl/articles/1191210.pdf
Data publikacji:
2016
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
GSM
UMTS
LTE
Network Achitecture
Security
Bandwidth
Opis:
The Global System for Mobile Communications (GSM) which is a standard for 2G (second generation) cellular networks has created an avenue for the development of 3G (third generation) and 4G (fourth Generation) cellular network standards such as Universal Mobile Telecommunications System (UMTS) and long term evolution (LTE). With the deployment of new technologies still on the way, the era beyond 3G and 4G requires that cellular and radio technologies need to work together forming highly heterogeneous networks, therefore this paper analyses already existing cellular network technologies such as LTE, GSM and UMTS in order to give a general understanding of their architectures, functional and evolutional dependencies and also to provide an evolutionary trend and a clear overview of the support provided for other telecommunications infrastructure.
Źródło:
World Scientific News; 2016, 54; 27-39
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pricing Rules Comparison in the Context of Bandwidth Trade
Autorzy:
Pałka, P.
Toczyłowski, E.
Powiązania:
https://bibliotekanauki.pl/articles/309148.pdf
Data publikacji:
2010
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
communication bandwidth trade
mechanism design
pricing rule
Opis:
In this paper we compare two pricing rules in the context of bandwidth trade. Allocation and pricing rules, together with a set of signals received from independent agents, constitute a market mechanism. In the paper we analyze two pricing rules: well known Vickrey-Clarke-Groves rule (VCG) and the parametric pricing rule (PPR).We apply these pricing rules to the allocation rule specified by the balancing communication bandwidth trade model (BCBT).
Źródło:
Journal of Telecommunications and Information Technology; 2010, 2; 61-66
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ensuring Equal Bandwidth for Remote Connections to the Local Company Server
Autorzy:
Muc, Adam
Muchowski, Tomasz
Kluczyk, Marcin
Szeleziński, Adam
Powiązania:
https://bibliotekanauki.pl/articles/2064809.pdf
Data publikacji:
2020
Wydawca:
STE GROUP
Tematy:
QOS
PCQ
bandwidth sharing
VPN
remote work
Opis:
Creating the required IT infrastructure to enable the ability for comfortable remote working is not an easy task. Improper configuration can create the possibility of taking over the whole bandwidth of the link by one device. Increasing bandwidth introduces extra costs and does not completely eliminate the problem – it will be more difficult to take over the whole bandwidth, but it is still possible. The solution to the problem may be the use of clouds and VPS, but it is associated with high costs and the need to entrust company data to providers of these services. Due to security and too high costs, this may not be an optimal solution. An alternative solution may be to use QoS along with PCQ. This mechanism allows to ensure equal division of the bandwidth between the devices under its control. With an appropriate configuration, QoS can eliminate the problem of taking over the whole bandwidth and ensure equal access to resources.
Źródło:
Multidisciplinary Aspects of Production Engineering; 2020, 3, 1; 285--295
2545-2827
Pojawia się w:
Multidisciplinary Aspects of Production Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Development and implementation of hash function for generating hashed message
Autorzy:
Noroozi, E.
Ghaeedi, A.
Powiązania:
https://bibliotekanauki.pl/articles/103361.pdf
Data publikacji:
2016
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
digital signature
steganography
bandwidth
authentication
hash message
Opis:
Steganography is a method of sending confidential information in a way that the existence of the channel in this communication remains secret. A collaborative approach between steganography and digital signature provides a high secure hidden data. Unfortunately, there are wide varieties of attacks that affect the quality of image steganography. Two issues that required to be addressed are large size of the ciphered data in digital signature and high bandwidth. The aim of the research is to propose a new method for producing a dynamic hashed message algorithm in digital signature and then embedded into image for enhancing robustness of image steganography with reduced bandwidth. A digital signature with smaller hash size than other hash algorithms was developed for authentication purposes. A hash function is used in the digital signature generation. The encoder function encoded the hashed message to generate the digital signature and then embedded into an image as a stego-image. In enhancing the robustness of the digital signature, we compressed or encoded it or performed both operations before embedding the data into the image. This encryption algorithm is also computationally efficient whereby for messages with the sizes less than 1600 bytes, the hashed file reduced the original file up to 8.51%.
Źródło:
Advances in Science and Technology. Research Journal; 2016, 10, 31; 31-39
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Polarization-independent metal-dielectric grating with improved bandwidth
Autorzy:
Wang, B
Li, H
Shu, W
Li, W
Li, C
Lei, L
Zhou, J
Powiązania:
https://bibliotekanauki.pl/articles/174684.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
rigorous coupled-wave analysis
reflective efficiency
improved bandwidth
Opis:
A polarization-independent reflective grating with improved bandwidth is presented based on the mixed metal-dielectric grating. The novel grating is composed of the substrate, the metal slab, two dielectric layers, and the covering layer. The grating parameters are optimized for the special duty cycle of 0.6 at an incident wavelength of 1550 nm used in dense wavelength division multiplexing (DWDM). With the designed grating, high efficiency can be diffracted into the reflective –1st order for both TE and TM polarizations, where the polarization-independence is exhibited. Most importantly, the efficiency of more than 90% can be achieved within the incident wavelength bandwidth of 1262–1686 nm, where the bandwidth is improved greatly compared with the reported surface-relief single-layer grating. The reflective grating can have advantages of high efficiency, polarization-independence, and wide bandwidth, which should be useful for DWDM applications.
Źródło:
Optica Applicata; 2015, 45, 1; 71-77
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new approach to header compression in secure communications
Autorzy:
Karg, C.
Lies, M.
Powiązania:
https://bibliotekanauki.pl/articles/307938.pdf
Data publikacji:
2006
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
IPv6
header compression
IP security
restricted bandwidth
Opis:
The paper presents a new header compression mechanism for the IPv6 protocol. Its main benefit is the reduction of the overhead caused by IPSec tunnel mode which enlarges datagrams in order to provide security services such as authentication and secrecy.
Źródło:
Journal of Telecommunications and Information Technology; 2006, 3; 3-8
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multicommodity Auction Model for Indivisible Network Resource Allocation
Autorzy:
Kołtyś, K.
Pałka, P.
Toczyłowski, E.
Żołtowska, I.
Powiązania:
https://bibliotekanauki.pl/articles/307940.pdf
Data publikacji:
2008
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
bandwidth allocation
indivisible commodities
modularity
multicommodity trade
pricing
Opis:
In this paper we present the multicommodity auction model BCBT-I that allocates indivisible network resources among bidders. The approach can be considered as a generalization of the basic multicommodity model for balancing communication bandwidth trade (BCBT). The BCBT model assumes that offers concerning inter-node links and point-to-point bandwidth demands can be realized partially. However, in the real-world trade there might be a need to include capacity modularity in the market balancing process. Thus we state the model for balancing communication bandwidth trade that takes into account the indivisibility of traded bandwidth modules. This requires to solve a mixed integer problem and increases computational complexity. Furthermore, the pricing issue appears nontrivial, as the dual prices cannot be longer used to set fair, competitive market prices. For clearing the market, we examine the multicommodity pricing mechanizm based on differentiation of buy and sell market prices.
Źródło:
Journal of Telecommunications and Information Technology; 2008, 4; 60-66
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The new data exchange facilities with CAN-FD
Autorzy:
Śmieja, M.
Duda, K.
Mamala, J.
Powiązania:
https://bibliotekanauki.pl/articles/247556.pdf
Data publikacji:
2016
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
automotive
communication networks
CAN
CAN-FD
transmission bandwidth
Opis:
The modern vehicles demand more and more data exchange to coordinate, control and monitor functions of on board system. The variety of networks applied in these systems is featured mainly by the bandwidth and time determinism. The development electronic information and network sciences find its reflection in the new and new automotive implementations. The last significant step towards the increase the throughout put of the on board network channels are works on CAN-FD. CAN is now the most common network present on board. It helps to manage the maintenance with the numerous subassemblies of the modern car. Next to the many features making CAN so useful and popular, there is a bandwidth limitation, which slows down further implementation of it. The new CAN-FD specification adds new properties that extend the possibilities of CAN as automotive network protocol. These are: different speed transmission in the arbitration phase and in the data phase during the message transmission as well as the extending the maximum size of data filed of the frame from 8 (CAN) to 64 (CAN-FD). In the paper there have been presented the limitations of existing CAN protocol usage, the explanation of the basics of the arbitration mechanisms and the response of the scientist and engineers to cope with it, as well as the formal result outlined in the CAN-FD specification.
Źródło:
Journal of KONES; 2016, 23, 4; 527-533
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of the impact of the frequency range of the tensometer bridge and projectile geometry on the results of measurements by the split Hopkinson pressure bar method
Autorzy:
Moćko, W.
Powiązania:
https://bibliotekanauki.pl/articles/220701.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Hopkinson bar
tensometer bridge
amplifier bandwidth
strain measurement
Opis:
The paper presents the results of the analysis of the striker shape impact on the shape of the mechanical elastic wave generated in the Hopkinson bar. The influence of the tensometer amplifier bandwidth on the stress-strain characteristics obtained in this method was analyzed too. For the purposes of analyzing under the computing environment ABAQUS / Explicit the test bench model was created, and then the analysis of the process of dynamic deformation of the specimen with specific mechanical parameters was carried out. Based on those tests, it was found that the geometry of the end of the striker has an effect on the form of the loading wave and the spectral width of the signal of that wave. Reduction of the striker end diameter reduces unwanted oscillations, however, adversely affects the time of strain rate stabilization. It was determined for the assumed test bench configuration that a tensometric measurement system with a bandwidth equal to 50 kHz is sufficient.
Źródło:
Metrology and Measurement Systems; 2013, 20, 4; 555-564
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of open multi-commodity market data model on the communication bandwidth market
Autorzy:
Kasprzak, P.
Kaleta, M.
Pałka, P.
Smoliła, K.
Toczyłowski, E.
Traczyk, T.
Powiązania:
https://bibliotekanauki.pl/articles/308563.pdf
Data publikacji:
2007
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
communication bandwidth trade
market clearing
multi-commodity trade
Opis:
In the paper the market model for balancing communication bandwidth trade (BCBT) is analyzed in the form of multi-commodity market data model (M3). The distinguishing feature of BCBT model is that it assumes that market players can place buy offers not only for isolated network resources - inter-node links, but also for end-to-end network paths of predefined capacity, that is, every offer concerns a point-to-point bandwidth connection between a pair of specified locations in a communication network. The model enables effective balancing of sell and buy offers for network resources in a way which maximizes global economic welfare. The open multi-commodity market data model provides efficient and clear mechanisms, which support the environment of auctions and multi-commodity exchanges, especially when the trade is constrained by the infrastructure resources. Thus the model may be used in designing open information systems for market balancing and clearing in the context of multicommodity trade in various network infrastructure sectors.
Źródło:
Journal of Telecommunications and Information Technology; 2007, 4; 45-50
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Observation of WiMAX Radio Parameters to Enhance Spectrum Utilization in Mixed Environment
Autorzy:
Kowalik, K.
Kliks, A.
Musznicki, B
Kołodziejski, M.
Kryszkiewicz, P.
Powiązania:
https://bibliotekanauki.pl/articles/307572.pdf
Data publikacji:
2018
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
5G
bandwidth sharing
spectrum utilization
statistical characteristics
WiMAX
Opis:
It is believed that 5G networks will provide 1000 times more capacity than current solutions. One of the keys to achieve that goal is not only the utilization of additional radio bands, but also and foremost, the dynamic and efficient spectrum sharing. To successfully implement it such feature statistical observation and analysis of currently operational legacy systems are required. Comprehensive data on the signal parameters will allow then to determine and tune the approach to simultaneous bandwidth usage by existing and new systems. Therefore, to define and introduce the problem this paper presents a conceptual analysis of IEEE 802.16e based WiMAX network operating in the 3.6--3.8 GHz band on the eve of spectrum sharing introduction.
Źródło:
Journal of Telecommunications and Information Technology; 2018, 1; 42-50
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Available Bandwidth and RSRP Based Handover Algorithm for LTE/LTE-Advanced Networks Tested in LTE-Sim Simulator
Autorzy:
Angri, Ismail
Najid, Abdellah
Mahfoudi, Mohammed
Powiązania:
https://bibliotekanauki.pl/articles/226002.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
mobility management
handover
LTE
lte-sim
available bandwidth
RSRP
Opis:
In this paper, we propose a new algorithm that improves the performance of the operation of Handover (HO) in LTE-Advanced (LTE-A) networks. As recognized, Mobility Management (MM) is an important pillar in LTE/LTE-A systems to provide high quality of service to users on the move. The handover algorithms define the method and the steps to follow to ensure a reliable transfer of the UEs from one cell to another without interruption or degradation of the services offered by the network. In this paper, the authors proposed a new handover algorithm for LTE/LTE-A networks based on the measurement and calculation of two important parameters, namely the available bandwidth and the Received Power (RSRP) at the level of eNodeBs. The proposed scheme named LTE Available Bandwidth and RSRP Based Handover Algorithm (LABRBHA) was tested in comparison with well-known algorithms in the literature as the LHHA, LHHAARC and the INTEGRATOR scheme using the open source simulator LTE-Sim. Finally, the network performances were investigated via three indicators: the number of lost packets during the handover operation, the latency as well as the maximum system throughput. The results reported that our algorithm shows remarkable improvements over other transfer schemes.
Źródło:
International Journal of Electronics and Telecommunications; 2019, 65, 1; 85-93
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bandwidth Estimation Using Network Calculus in Practice
Autorzy:
Wasielewska, Katarzyna
Borys, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/226756.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
bandwidth estimation
network calculus
quality of service
internet traffic
Opis:
An available bandwidth at a link is an unused capacity. Its measuring and/or estimation is not simple in practice. On the other hand, we know that its continuous knowledge is crucial for the operation of almost all networks. Therefore, there is a continuous effort in improving the existing and developing new methods of available bandwidth measurement and/or estimation. This paper deals with these problems. Network calculus terminology allows to express an available bandwidth in terms of a service curve. The service curve is a function representing a service available for a traffic flow which can be measured/estimated in a node as well as at an end-to-end connection of a network. An Internet traffic is highly unpredictable what hinders to a large extent an execution of the tasks mentioned above. This paper draws attention to pitfalls and difficulties with application of the existing network calculus methods of an available bandwidth estimation in a real Internet Service Provider (ISP) network. The results achieved in measurements have been also confirmed in simulations performed as well as by mathematical considerations presented here. They give a new perspective on the outcomes obtained by other authors and on their interpretations.
Źródło:
International Journal of Electronics and Telecommunications; 2019, 65, 1; 133-138
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multivariate kernel density estimation with a parametric support
Autorzy:
Jarnicka, J.
Powiązania:
https://bibliotekanauki.pl/articles/255530.pdf
Data publikacji:
2009
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
density estimation
kernel
bandwidth
kernel density estimator
EM algorithm
Opis:
We consider kernel density estimation in the multivariate case, focusing on the use of some elements of parametric estimation. We present a two-step method, based on a modification of the EM algorithm and the generalized kernel density estimator, and compare this method with a couple of well known multivariate kernel density estimation methods.
Źródło:
Opuscula Mathematica; 2009, 29, 1; 41-55
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimization of Spectrum Sensing Parameters in Cognitive Radio Using Adaptive Genetic Algorithm
Autorzy:
Chatterjee, S.
Dutta, S.
Bhattacharya, P. P.
Roy, J. S.
Powiązania:
https://bibliotekanauki.pl/articles/308511.pdf
Data publikacji:
2017
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
adaptive genetic algorithm
bandwidth
cognitive radio
spectrum sensing
throughput
Opis:
Quality of service parameters of cognitive radio, like, bandwidth, throughput and spectral efficiency are optimized using adaptive and demand based genetic algorithm. Simulation results show that the proposed method gives better real life solution to the cognitive radio network than other known approach.
Źródło:
Journal of Telecommunications and Information Technology; 2017, 1; 21-27
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Flexible coupling of drive and guide elements for parallel-driven feed axes to increase dynamics and accuracy of motion
Autorzy:
Peukert, C.
Merx, M.
Müller, J.
Ihlenfeldt, S.
Powiązania:
https://bibliotekanauki.pl/articles/99992.pdf
Data publikacji:
2017
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
compliant mechanism
parallel-driven feed axis
machine tool
control bandwidth
Opis:
Productivity enhancement is achievable by increasing the dynamics of machines. This can be accomplished by decreasing the moving mass or by increasing the driving forces. One possibility for increasing the drive forces lies in the use of multiple parallel-acting actuators. Because of the mechanical coupling between the drives, undesirable interference of the actuators occurs. This limits the control bandwidth of the feed axis. Feed axes of machine tools are mostly equipped with linear guides fitted with rolling elements. Since they dispose of just one degree of freedom, small errors in their alignment or thermally induced errors cause constraining loads. In this paper compliant mechanisms are used to mechanically decouple the slide from the guide and drive elements. The application of flexible joints in gantry axes with linear motors and ball screws is investigated. The dynamic behaviour of the feed axis components are modelled using the Finite Element Method. By applying the modal reduction technique, the dynamic behaviour is included in an elastic multibody simulation. With the mechanical decoupling of the drive and guide elements it is possible to increase the control bandwidth of the system. Deviations in motion may also be corrected with parallel-driven feed axis by applying compliant mechanisms.
Źródło:
Journal of Machine Engineering; 2017, 17, 2; 77-89
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bandwidth Trading: A Comparison of the Combinatorial and Multicommodity Approach
Autorzy:
Kołtyś, K.
Pałka, P.
Toczyłowski, E.
Żółtowska, I.
Powiązania:
https://bibliotekanauki.pl/articles/309152.pdf
Data publikacji:
2010
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
bandwidth allocation
combinatorial auction
computational efficiency
ndivisible resources
multicommodity trade
Opis:
Since the telecommunication market becomes more complex and dynamic, a strong need for a new, efficient and flexible bandwidth trading mechanisms appears. We believe that good mechanisms, that allow effective and fair allocation of bandwidth between market participants will help to develop the real competitive bandwidth market. In this paper we compare two different double-sided bandwidth auction mechanisms, that seem to be well suited approaches for trading indivisible units of bandwidth: combinatorial auction c-SeBiDA and multicommodity mechanism BACBR-I. The c-SeBiDA mechanism considers two types of commodities: inter-node links and paths consisting of particular links. Market participants may bid a single link, or a bundle of links, constituting a specific path. The BACBR-I mechanism is a multicommodity exchange model, that allows bidders to place buy offers not only for individual or bundled links, but rather for end-to-end connections. Therefore, it is the decision model that allocates the most efficient links to connections. We run a large set of experiments to test the allocation and computational efficiency obtained under both approaches.
Źródło:
Journal of Telecommunications and Information Technology; 2010, 2; 67-72
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimisation of Multistep Cavity Configuration to Extend Absorption Bandwidth of Micro Perforated Panel Absorber
Autorzy:
Falsafi, I.
Ohadi, A.
Powiązania:
https://bibliotekanauki.pl/articles/176825.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
micro perforated panel
MPP
multistep cavity
absorption bandwidth
optimisation
impedance tube
Opis:
Micro perforated panel (MPP) absorber is a new form of acoustic absorbing material in comparison with porous ones. These absorbers are considered as next generation ones and the best alternative for traditional porous materials like foams. MPP combined with a uniform air gap constructs an absorber which has high absorption but in a narrow bandwidth of frequency. This characteristic makes MPPAs insufficient for practical purposes in comparison with porous materials. In this study instead of using a uniform air gap behind the MPP, the cavity is divided into several partitions with different depth arrangement which have parallel faces. This method improves the absorption bandwidth to reach the looked for goal. To achieve theoretical absorption of this absorber, equivalent electro-acoustic circuit and Maa’s theory (MAA, 1998) are employed. Maa suggested formulas to calculate MPP’s impedance which show good match with experimental results carried out in previous studies. Electro-acoustic analogy is used to combine MPP’s impedance with acoustic impedances of complex partitioned cavity. To verify the theoretical analyses, constructed samples are experimentally tested via impedance tube. To establish the test, a multi-depth setup facing a MPP is inserted into impedance tube and the absorption coefficient is examined in the 63-1600 Hz frequency range. Theoretical results show good agreement compared to measured data, by which a conclusion can be made that partitioning the cavity behind MPP into different depths will improve absorption bandwidth and the electro-acoustic analogy is an appropriate theoretical method for absorption enhancement research, although an optimisation process is needed to achieve best results to prove the capability of this absorber. The optimisation process provides maximum possible absorption in a desired frequency range for a specified cavity configuration by giving the proper cavity depths. In this article numerical optimisation has been done to find cavity depths for a unique MPP.
Źródło:
Archives of Acoustics; 2018, 43, 2; 187-195
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Open concurrent network communication methods in building distributed Web applications
Autorzy:
Buchwald, Paweł
Dawid, Aleksander
Powiązania:
https://bibliotekanauki.pl/articles/1986993.pdf
Data publikacji:
2021-12-30
Wydawca:
Politechnika Gdańska
Tematy:
WebRTC
e-learning
LTE
LAN
WiFi
video transmission
jitter
delay
bandwidth
Opis:
The attractiveness of real-time multimedia communication as part of an e-learning platform largely depends on the quality of the telecommunications infrastructure and on theservices that support the exchange of audiovisual data. The research subject of this workis communication between stationary and mobile devices using distributed services such as Web Real-Time Communication (WebRTC) running in HTML5 compliant web browsers. The test connections were carried out in a peer-to-peer architecture over a local wireless WiFi network and a mobile network supporting the Long Term Evolution (LTE) standard for data interchange. Several audiovisual sessions between two clients were analyzed for different connection scenarios. Parameters responsible for the transmission quality, such as delay, jitter,packet loss, or the speed of sending and receiving video frames were measured for each scenario. Open audiovisual communication system performance experiments were conducted under real operating conditions. The obtained results indicated potential applications in the development of e-learning websites.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2021, 25, 4; 409-418
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design and Simulation of 2× 2Micro Strip Circular Patch Antenna Array at 28 GHz for 5G Mobile Station Application
Autorzy:
Hasan, Salim Abdullah
Ahmed, Abdulsattar Mohamed
Abdulqader, Mohanad Nawfal
Dawood, Younis Shareef
Powiązania:
https://bibliotekanauki.pl/articles/2200728.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
patch
5G
return loss
dielectric
array
divider
substrate
directivity
bandwidth
Opis:
This paper proposes the design and simulation of 2×2 circular patch antenna array working at 28 GHz by using four inset feed micro strip circular patch antennas to achieve beam forming with directivity around 13dB which is required to overcome part of high path loss challenge for high data rate mm-5G mobile station application. Four element 2x2 array consists of two 1x2 circular patch antenna arrays based on power divider and quarter wavelength transition lines as a matching circuit. The designed antenna array is simulated on RT/duroid 5880 dielectric substrate with properties of 0.5mm thickness, dielectric constant ε r =2.2, and tangent loss of 0.0009 by using Computer System Technology (CST) software. The performances in terms of return loss, 3D–radiation pattern is evaluated at 28 GHz frequency band. The design also includes the possibility of inserting four identical 2x2 antenna arrays at four edges of mobile station substrate to achieve broad space coverage by steering the beams of the mobile station arrays.
Źródło:
International Journal of Electronics and Telecommunications; 2022, 68, 4; 721--729
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
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