Skocz do pozycji: 1.

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

/5

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Skocz do pozycji: 2.

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

/5

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Skocz do pozycji: 3.

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

/5

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Skocz do pozycji: 4.

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

/5

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Skocz do pozycji: 5.

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

/5

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Skocz do pozycji: 6.

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

/5

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Skocz do pozycji: 7.

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

/5

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Skocz do pozycji: 8.

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

/5

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Skocz do pozycji: 9.

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

/5

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Skocz do pozycji: 10.

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

/5

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Skocz do pozycji: 11.

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

/5

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Skocz do pozycji: 12.

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

/5

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Skocz do pozycji: 13.

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

/5

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Skocz do pozycji: 14.

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

/5

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Skocz do pozycji: 15.

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

/5

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Skocz do pozycji: 16.

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

/5

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Skocz do pozycji: 17.

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

/5

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Skocz do pozycji: 18.

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

/5

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Skocz do pozycji: 19.

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

/5

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Skocz do pozycji: 20.

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

/5

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Skocz do pozycji: 21.

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

/5

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Skocz do pozycji: 22.

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

/5

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Skocz do pozycji: 23.

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

/5

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Skocz do pozycji: 24.

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

/5

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Skocz do pozycji: 25.

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

/5

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Skocz do pozycji: 26.

Tytuł:

Limitations of WSSUS modeling of stationary underwater acoustic communication channel

Autorzy:

Kochańska, I.
Nissen, I.

Powiązania:

https://bibliotekanauki.pl/articles/331730.pdf

Data publikacji:

2016

Wydawca:

Polskie Towarzystwo Akustyczne

Tematy:

underwater communications
impulse response
stationary time
stationary bandwidth
adaptive communications
WSSUS modeling

Opis:

Performances of underwater acoustic communication (UAC) systems are strongly related to specific propagation conditions of the underwater channel. Due to their large variability, there is a need for adaptive matching of the UAC systems signaling to the transmission properties of the channel. This requires a knowledge of instantaneous channel characteristics, in terms of the specific parameters of stochastic models. The wide-sense stationary uncorrelated scattering (WSSUS) assumption simplifies the estimation of terrestrial wireless channel transmission properties. Although UAC channels are hardly ever WSSUS, the rationale of such a stochastic modeling is that over a short period of time, and for a limited frequency range, this assumption is reasonably satisfied. The limits of application of the local-sense stationary uncorrelated scattering (LSSUS) model are determined by the stationary time and frequency. This paper presents the results of LSSUS model analysis for UAC channel measurements gathered by the former Research Department for Underwater Acoustics and Marine Geophysics (FWG), now part of the WTD71, during the SIMO experiment in the Bornholm Basin of the Baltic Sea.

Źródło:

Hydroacoustics; 2016, 19; 229-238
1642-1817

Pojawia się w:

Hydroacoustics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 27.

Tytuł:

Synthesis method for distributed amplifiers

Autorzy:

Zólomy, A.

Powiązania:

https://bibliotekanauki.pl/articles/309227.pdf

Data publikacji:

2003

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

wzmacniacz
synchronizacja fazowa
distributed amplifier
gain-bandwidth products
phase synchronization
optical receivers

Opis:

New design method is presented for distributed amplifiers (DA). It is shown that by proper design of the applied transmission lines (TL) between the active devices the image impedance and the cut-off frequency (COF) of the input or output line of the DA can be independently tuned. As a consequence, the phase mismatch between the lines of the DA can be adjusted independently from the termination conditions and from the capacitances of the applied transistor and thus flat gain characteristic can be achieved. The method is well applicable for nearly unilateral devices like HBTs [1] and yields the highest gain-bandwidth product.

Źródło:

Journal of Telecommunications and Information Technology; 2003, 1; 20-23
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 28.

Tytuł:

A concept of Differentiated Services architecture supporting military oriented Quality of Service

Autorzy:

Kwiatkowski, M.

Powiązania:

https://bibliotekanauki.pl/articles/307725.pdf

Data publikacji:

2003

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

quality of service
military networks
differentiated services
bandwidth brokerage
policy based network management

Opis:

This paper presents a concept of IP Differentiated Services (DiffServ) architecture in conjunction with bandwidth brokerage and policy based network management, all aimed at efficient and flexible provision of the military oriented Quality of Service (M-QoS) features in the Australian Defence (strategic) wide area network and its satellite trunk interconnections with the tactical domain. Typical DiffServ functions are analysed in the paper with regard to their roles in offering M-QoS. Some preliminary simulation results of applying these mechanisms to achieve traffic policing and differentiation for (UDP) video traffic streams, are also presented. Finally, the paper proposes the use of bandwidth brokerage in each DiffiServ domain to facilitate automatic Service Level Specification (SLS) arrangements with end-user applications, and policy based network management to support the flexible implementation of bandwidth brokerage.

Źródło:

Journal of Telecommunications and Information Technology; 2003, 2; 71-76
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 29.

Tytuł:

QoS Equalization in a W-CDMA Cell Supporting Calls of Innite or Finite Sources with Interference Cancelation

Autorzy:

Moscholios, I. D.
Kallos, G. A.
Katsiva, M. A.
Vassilakis, V. G.
Logothetis, M. D.

Powiązania:

https://bibliotekanauki.pl/articles/308455.pdf

Data publikacji:

2014

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

bandwidth reservation
infinite sources
finite sources
recursive formula
time-call congestion probabilities
WCDMA

Opis:

In this paper, a multirate loss model for the calculation of time and call congestion probabilities in a Wideband Code Division Multiple Access (W-CDMA) cell is considered. It utilizes the Bandwidth Reservation (BR) policy and supports calls generated by an infinite or finite number of users. The BR policy achieves QoS equalization by equalizing congestion probabilities among calls of dierent service-classes. In the proposed models a multiple access interference is considered, and the notion of local blocking, user's activity and interference cancelation. Although the analysis of the proposed models reveals that the steady state probabilities do not have a product form solution, the authors show that the calculation of time and call congestion probabilities can be based on approximate but recursive formulas, whose accuracy is verified through simulation and found to be quite satisfactory.

Źródło:

Journal of Telecommunications and Information Technology; 2014, 3; 63-70
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 30.

Tytuł:

Auction Models Supporting End-to-End Connection Trading

Autorzy:

Kołtyś, K.
Pieńkosz, K.
Toczyłowski, E.

Powiązania:

https://bibliotekanauki.pl/articles/309215.pdf

Data publikacji:

2012

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

bandwidth allocation
divisible commodities
end-to-end connections
multi-commodity trade
multipath routing

Opis:

The paper concerns bandwidth allocation problem on the telecommunication market where there are many sellers and buyers. Sellers offer the bandwidth of telecommunication links. Buyers are interested in the purchase of the bandwidth of several links that makes up an end-to-end connection between two nodes of telecommunication network. We analyze three auction models supporting such a bandwidth exchange: NSP (network second price), BCBT (model for balancing communication bandwidth trading) and BCBT-CG which is a modification of BCBT that applies column generation technique. All of these models concern divisible network resources, treat bandwidth of telecommunication links as an elementary commodity offered for sale, and allow for purchasing bandwidth along multiple paths joining two telecommunication nodes. All of them also aim at maximizing the social welfare. Considered auction models have been compared in the respect of economic and computational efficiency. Experimental studies have been performed on several test instances based on the SNDlib library data sets.

Źródło:

Journal of Telecommunications and Information Technology; 2012, 2; 55-62
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 31.

Tytuł:

A Contribution to the System : Theoretic Approach to Bandwidth Estimation

Autorzy:

Borys, A.
Wasielewska, K.
Rybarczyk, D.

Powiązania:

https://bibliotekanauki.pl/articles/226012.pdf

Data publikacji:

2013

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

network calculus
rate chirps
bandwidth estimation
nonlinear and/or linear parametric traffic systems

Opis:

The network calculus provides a theoretical background for description of traffic in computer networks. Using this tool in explanation of the so-called pathchirp method of measuring the available bandwidth, the validity and range of application of some relationships exploited are verified in this paper. The derivations are carried out in a wider context than that considered in a recent paper by Liebeherr et al. published in IEEE/ACM Transactions on Networking on network bandwidth estimation, providing thereby new insights and outcomes. These results, summarized in a table, show a means of bounding the service curve, depending upon its convexity or non-convexity property assumed and upon the linearity or non-linearity of a network considered. Moreover, it is shown here that the nonlinear network example analyzed by Liebeherr et al. can be viewed equivalently as a linear parametric network. For this network, the behaviour of the cross traffic is considered in a more detail, too.

Źródło:

International Journal of Electronics and Telecommunications; 2013, 59, 2; 141-149
2300-1933

Pojawia się w:

International Journal of Electronics and Telecommunications

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 32.

Tytuł:

Comparison of determination methods of vibrations damping coefficients for complex structures

Autorzy:

Flaga, A.
Szulej, J.
Wielgos, P.

Powiązania:

https://bibliotekanauki.pl/articles/390348.pdf

Data publikacji:

2008

Wydawca:

Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej

Tematy:

damping
potential energy method
kinetic energy method
collocation method
half-power bandwidth method

Opis:

The purpose of this paper is to present methods of vibrations damping coefficient determination. The methods, such as collocation method, two energetic methods and half-power bandwidth method concern composite structures. The verification of methods has been taken into account in this work. Two real compound models and two numerical models have been created. Time series of vibrations of these models have been measured and calculated. The comparison of four methods has been made on the basis of obtained results.

Źródło:

Budownictwo i Architektura; 2008, 3, 2; 53-61
1899-0665

Pojawia się w:

Budownictwo i Architektura

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 33.

Tytuł:

A novel approach to enhance the performance of mobile ad hoc network (manet) through a new bandwidth optimization technique

Autorzy:

Rahman, Md. Torikur

Powiązania:

https://bibliotekanauki.pl/articles/117738.pdf

Data publikacji:

2019

Wydawca:

Polskie Towarzystwo Promocji Wiedzy

Tematy:

MANET
leaky bucket
token bucket
delay
bandwidth optimization
komunikacja mobilna
opóźnienie
optymalizacja przepustowości

Opis:

Now is the age of information technology. World is advancing day by day. At present in this progressing world communication from one place to another has become so easy, less costly, and faster. This modern life is almost impossible with the help of these communication technologies. People need to talk, need to share data, need to express their emotion from long distance. So they need to use technologies to communicate with one another. Nowadays the fields of MANET have yielded more and more popularity and thus MANET have become a subject of great interest for the researchers to enforce research activities. Mobile Ad Hoc Network (MANET) is the cooperative engagement of a collection of mobile nodes without the required intervention of any centralized access point or existing infrastructure. There is an increasing trend to adopt mobile ad hoc networking for commercial uses. Mobile Ad Hoc Network (MANET) is an emerging area of research to provide various communication services to the end users. But these communication services of Mobile Ad Hoc Network (MANET) use high capacity of bandwidth and a big amount of internet speed. Bandwidth optimization is indispensable in various communications for successful acceptance and deployment of such a technology. Thinking of this, I propose a New Bandwidth Optimization Technique that Enhance the Performance of Mobile Ad Hoc Network (MANET). The new Bandwidth optimization technique which is more efficient in terms of time delay in Mobile Ad Hoc Network (MANET) can redirect a new way towards optimization development in network communication and device junction technology.

Źródło:

Applied Computer Science; 2019, 15, 2; 42-52
1895-3735

Pojawia się w:

Applied Computer Science

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 34.

Tytuł:

Bandwidth Enhancement for Half Mode Substrate Integrated Waveguide Antenna using Defected Ground Structures

Autorzy:

Astuti, Dian Widi
Rivayanto
Muslim
Simanjuntak, Imelda
Firmansyah, Teguh
Cahyasiwi, Dwi Astuti
Natali, Yus

Powiązania:

https://bibliotekanauki.pl/articles/27311970.pdf

Data publikacji:

2023

Wydawca:

Polska Akademia Nauk. Czasopisma i Monografie PAN

Tematy:

Bandwidth enhancement
dual cavity
half modesubstrate integrated waveguide
defected ground structure
U-slot

Opis:

The SIW antenna suffers from the narrow bandwidth for a single cavity and single resonant. Defected ground structure (DGS) with a dual cavity was the solution to solve narrow bandwidth by resulting in hybrid resonance. The hybrid resonance with 14.83% impedance bandwidth is proposed in this antenna design. The first resonance resulted from the combination of the TE101 modes from inner and outer HMSIW cavities while the second resonance resulted from the combination of the strong TE101 and the weak TE102 mode from the inner HMSIW cavity and the addition of the weak TE101 from the outer HMSIW cavity. The measurement antenna design has a broadband antenna with a 14.31% (5.71 – 6.59 GHz) impedance bandwidth by using substrate Rogers RO 5880.

Źródło:

International Journal of Electronics and Telecommunications; 2023, 69, 3; 449--454
2300-1933

Pojawia się w:

International Journal of Electronics and Telecommunications

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 35.

Tytuł:

Effects of using various methods for car shock absorbers diagnostic tests

Autorzy:

Guzek, Marek
Zdanowicz, Piotr

Powiązania:

https://bibliotekanauki.pl/articles/263600.pdf

Data publikacji:

2020

Wydawca:

Sieć Badawcza Łukasiewicz. Przemysłowy Instytut Motoryzacji

Tematy:

shock absorbers testing
EUSAMA test
phase angle method
half-power bandwidth method
simulation tests

Opis:

The work concerns the diagnostic assessment of the technical condition of the car suspension. The paper discusses practical problems that usually appear during testing of car shock absorbers mounted in a vehicle. The results of experimental tests for passenger car, carried out according to the EUSAMA standard test, were compared with the results obtained using newer methods (phase angle method and half power bandwidth method - HPBM). The article also deals with the issue of incompatibility of typical excitation at diagnostic devices for testing suspension with the one that often occurs in road conditions (by simulation method). The main purpose of the work was to assess the usefulness and reliability of various diagnostic methods intended for the testing of vehicle shock absorbers without disassembly them from the vehicle. The analyses carried out indicated the advantages and disadvantages of these methods in practice. It is also shown that the conditions of diagnostic tests correspond poorly to the operating conditions of the shock absorbers under normal vehicle operating conditions. An important factor in this case is the sliding friction in the suspension.

Źródło:

Archiwum Motoryzacji; 2020, 88, 2; 99-108
1234-754X
2084-476X

Pojawia się w:

Archiwum Motoryzacji

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 36.

Tytuł:

Impact of network architecture and aggregation proces on bandwidth allocation in wireless sensor networks

Autorzy:

Azizi, T.
Beghdad, R.

Powiązania:

https://bibliotekanauki.pl/articles/1839115.pdf

Data publikacji:

2018

Wydawca:

Polska Akademia Nauk. Instytut Badań Systemowych PAN

Tematy:

data aggregation
TDMA
bandwidth
superframe length
time slot
tree-based and spiral-based architecture

Opis:

Assigning bandwidth to sensors in a Wireless Sensor Network (WSN), while using Time Division Multiple Access (TDMA) protocol, remains an important problem. Even if many solutions were proposed in the literature, nevertheless, and since 2013, we are mainly focused on the critical study and the improvement of Masri’s approach published in Telecommunication Systems journal. In this paper, we introduce an extended version of our previous approaches (see Tarek Azizi and Rachid Beghdad, 2013, 2014, 2016) based on three fundamental concepts: network architecture, TDMA protocol, and data aggregation, in order to assign the maximum bandwidth to all sensor nodes. Three solutions will be presented in detail: Spiral-Based Clustered Data Aggregation (SBCDA) architecture, Tree-Based Clustered Data Aggregation (TBCDA), and Tree-Based ClusteredWireless Sensor Network (TBC-WSN). Aggregating data can reduce the number of the packets transmitted to the sink. This is the reason why, in the three approaches here described, each cluster head (CH) collects and aggregates received packets from its child nodes, before transmitting the resulting packet to its parent, until the data reaches the sink node (base station). With a number of simulations, we will demonstrate that our approaches are very competitive with Masri’s proposition, and also with two other recent works.

Źródło:

Control and Cybernetics; 2018, 47, 4; 411-437
0324-8569

Pojawia się w:

Control and Cybernetics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 37.

Tytuł:

Measurement of impulse response of shallow water communication channel by correlation method

Autorzy:

Schmidt, J.
Kochańska, I.
Schmidt, A.

Powiązania:

https://bibliotekanauki.pl/articles/331786.pdf

Data publikacji:

2017

Wydawca:

Polskie Towarzystwo Akustyczne

Tematy:

underwater communications
impulse response
delay spread
Doppler spread
coherence time
coherence bandwidth
PRBS
HFM

Opis:

Performances of underwater acoustic communication (UAC) systems are strongly related to specific propagation conditions of the underwater channel; conditions that can additionally change in time due to the movement of the acoustic system transmitter and receiver or to reflection by underwater objects of the transmitted signal. The time-varying impulse response is a comprehensive description of dynamically changing transmission properties of the UAC channel. It is a basis for estimation of stochastic parameters used for designing the signaling scheme of the communication system. The paper presents the results of a measurement experiment conducted in a shallow water environment. The channel impulse response was measured by the correlation method with the use of two kinds of broadband signals: pseudo-random binary sequence (PRBS) and hyperbolic frequency modulation chirp (HFM). For each measurement result statistical transmission parameters, namely delay spread, Doppler spread, coherence time, and coherence bandwidth were estimated.

Źródło:

Hydroacoustics; 2017, 20; 149-158
1642-1817

Pojawia się w:

Hydroacoustics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 38.

Tytuł:

Microwave harmonic generation in fiber-optical links

Autorzy:

Hilt, A.

Powiązania:

https://bibliotekanauki.pl/articles/308140.pdf

Data publikacji:

2002

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

optical transmission
fiber dispersion
microwaves
harmonics
IM/DD
coherent model
fiber length-bandwidth product

Opis:

Optical transmission of microwave (MW) and millimeter-wave (MMW) signals has become an intensive research area in the last decade. There is a growing interest in optical processing of MW signals [1,2], phased array applications [3] and wireless distribution of broadband data in fiber-fed MMW subscriber access systems [4 - 10]. This paper extends the existing models of MW/MMW optical links that are based on optical intensity [10, 11]. The model is suitable for estimating harmonic levels of the MW modulation signal generated in the optical path. Considering a MW fiber-optic link both the optical transmitter and the receiver are responsible for harmonic generation. Furthermore, the optical fiber itself inserted between the transmitter and receiver induces harmincs due to dispersion. Exact modelling of harmonic generation requires a calculation based on the optical field instead of on a purely intensity basis [12 -14].

Źródło:

Journal of Telecommunications and Information Technology; 2002, 1; 22-28
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 39.

Tytuł:

Call Blocking Probabilities of Multirate Elastic and Adaptive Traffic under the Threshold and Bandwidth Reservation Policies

Autorzy:

Moscholios, I. D.
Logothetis, M. D.
Boucouvalas, A. C.
Vassilakis, V. G.

Powiązania:

https://bibliotekanauki.pl/articles/308771.pdf

Data publikacji:

2016

Wydawca:

Instytut Łączności - Państwowy Instytut Badawczy

Tematy:

adaptive trac policy
Call Blocking Probabilities
Multirate Loss Model
threshold and bandwidth reservation policy

Opis:

This paper proposes multirate teletraffic loss models of a link that accommodates different service-classes of elastic and adaptive calls. Calls follow a Poisson process, can tolerate bandwidth compression and have an exponentially distributed service time. When bandwidth compression occurs, the service time of new and in-service elastic calls increases. Adaptive calls do not alter their service time. All calls compete for the available link bandwidth under the combination of the Threshold (TH) and the Bandwidth Reservation (BR) policies. The TH policy can provide different QoS among service-classes by limiting the number of calls of a service-class up to a predefined threshold, which can be different for each service-class. The BR policy reserves part of the available link bandwidth to benefit calls of high bandwidth requirements. The analysis of the proposed models is based on approximate but recursive formulas, whereby authors determine call blocking probabilities and link utilization. The accuracy of the proposed formulas is verified through simulation and found to be very satisfactory.

Źródło:

Journal of Telecommunications and Information Technology; 2016, 1; 44-52
1509-4553
1899-8852

Pojawia się w:

Journal of Telecommunications and Information Technology

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 40.

Tytuł:

Bandwidth selection for kernel generalized regression neural networks in identification of hammerstein systems

Autorzy:

Lv, Jiaqing
Pawlak, Mirosław

Powiązania:

https://bibliotekanauki.pl/articles/2031118.pdf

Data publikacji:

2021

Wydawca:

Społeczna Akademia Nauk w Łodzi. Polskie Towarzystwo Sieci Neuronowych

Tematy:

generalized regression neural network
nonparametric estimation
bandwidth
data-driven selection
nonlinear system
Hammerstein system

Opis:

This paper addresses the issue of data-driven smoothing parameter (bandwidth) selection in the context of nonparametric system identification of dynamic systems. In particular, we examine the identification problem of the block-oriented Hammerstein cascade system. A class of kernel-type Generalized Regression Neural Networks (GRNN) is employed as the identification algorithm. The statistical accuracy of the kernel GRNN estimate is critically influenced by the choice of the bandwidth. Given the need of data-driven bandwidth specification we propose several automatic selection methods that are compared by means of simulation studies. Our experiments reveal that the method referred to as the partitioned cross-validation algorithm can be recommended as the practical procedure for the bandwidth choice for the kernel GRNN estimate in terms of its statistical accuracy and implementation aspects.

Źródło:

Journal of Artificial Intelligence and Soft Computing Research; 2021, 11, 3; 181-194
2083-2567
2449-6499

Pojawia się w:

Journal of Artificial Intelligence and Soft Computing Research

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 41.

Tytuł:

The Human Governance Problem: Complex Systems and the Limits of Human Cognition

Autorzy:

Atreides, Kyrtin

Powiązania:

https://bibliotekanauki.pl/articles/31233773.pdf

Data publikacji:

2023

Wydawca:

Polska Akademia Nauk. Instytut Filozofii i Socjologii PAN

Tematy:

e-Governance
complexity
cognitive bandwidth
AGI
Artificial General Intelligence
scalability
tool AI
cognitive bias

Opis:

The impact of complexity within government and societal systems is considered relative to the limitations of human cognitive bandwidth, and the resulting reliance on cognitive biases and systems of automation when that bandwidth is exceeded. Examples of how humans and societies have attempted to cope with the growing difference between the rate at which the complexity of systems and human cognitive capacities increase respectively are considered. The potential of and urgent need for systems capable of handling the existing and future complexity of systems, utilizing greater cognitive bandwidth through scalable AGI, are also considered, along with the practical limitations and considerations in how those systems may be deployed in real-world conditions. Several paradoxes resulting from the influence of prolific Narrow Tool AI systems manipulating large portions of the population are also noted.

Źródło:

Filozofia i Nauka; 2023, 11; 37-64
2300-4711
2545-1936

Pojawia się w:

Filozofia i Nauka

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 42.

Tytuł:

Mid-infrared polarization beam splitter based on square/circular hybrid air holes with wide bandwidth and ultrashort length

Autorzy:

Zheng, Guang-Ming

Powiązania:

https://bibliotekanauki.pl/articles/2172822.pdf

Data publikacji:

2022

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

polarization beam splitter
mid-infrared
photonic crystal fibre
bandwidth
square air hole
circular air hole

Opis:

A novel mid-infrared polarization beam splitter (PBS) based on GaS is proposed. The high birefringence is achieved by using the cladding structure of alternating arrangement of square and circular air holes as well as introducing double elliptical air holes. The finite element method (FEM) is utilized to investigate the mode coupling characteristics in the proposed PBS. The results show that the highest extinction ratio of 115 dB and shortest length of only 40 μm can be realized at a wavelength of 4 μm. A wide bandwidth of 200 nm ranging from 3.9 to 4.1 μm is obtained.

Źródło:

Optica Applicata; 2022, 52, 3; 345--358
0078-5466
1899-7015

Pojawia się w:

Optica Applicata

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 43.

Tytuł:

Innowacyjne rozwiązania w branży TSL na przykładzie technologii przewozów w systemie Flexiwaggon
Innovative solutions in the TSL industry on the example of transport technology with using the Flexiwaggon system

Autorzy:

Auguściuk, Marek
Pawelczyk, Natalia

Powiązania:

https://bibliotekanauki.pl/articles/1194499.pdf

Data publikacji:

2019

Wydawca:

Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej

Tematy:

transport intermodalny
technologia Flexiwaggon
trasa E75
koszty
przepustowość
intermodal transport
Flexiwaggon technology
route E75
costs
bandwidth

Opis:

The paper presents the concept of using modern Flexiwaggon intermodal transport technology as well as the accompanying infrastructure and transhipment centres to plan transport processes in the TSL industry. The solution, which has not been used in Poland so far, has been proposed as an alternative possibility of transporting goods, currently transported by road, on the Polish section of route E75. The paper focuses on justifying why the use of the above technology is economically, temporarily and ecologically beneficial. Attention was also paid to the possibility of responding to unforeseen situations.

Źródło:

Journal of TransLogistics; 2019, 5, 1; 119-130
2450-5870

Pojawia się w:

Journal of TransLogistics

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 44.

Tytuł:

A Compact Quasi-Yagi Microstrip Patch Antenna with High Gain and Bandwidth for UWB Application

Autorzy:

Chowdhury, Hasanur Rahman
Hussain, Sakhawa

Powiązania:

https://bibliotekanauki.pl/articles/27311937.pdf

Data publikacji:

2023

Wydawca:

Polska Akademia Nauk. Czasopisma i Monografie PAN

Tematy:

Quasi Yagi microstrip patch antenna
FR4 substrate
ultra-wide bandwidth (UWB)
high antenna gain and low return loss

Opis:

A quasi-Yagi microstrip patch antenna with four directors and truncated ground plane has been designed and fabricated to have an ultra-wide bandwidth, high gain, low return loss and better directivity with center frequency at 3.40 GHz. After optimization, the proposed antenna yields an ultra-wide bandwidth of 1.20 GHz with lower and upper cutoff frequencies at 3.12 GHz and 4.32 GHz, respectively. High gain of 5.25 dB, return loss of -28 dB and directivity of 6.28 dB are obtained at resonance frequency of 3.40 GHz. The measured results of fabricated antenna have shown excellent agreement with the simulation results providing bandwidth of 1.34 GHz with lower and upper cutoff frequencies at 3.04 GHz and 4.38 GHz, respectively. The antenna gain of 5.33 dB, return loss of -44 dB are obtained at resonance frequency of 3.36 GHz. The dimension of the antenna is only of 65 mm x 45 mm ensuring compact in size.

Źródło:

International Journal of Electronics and Telecommunications; 2023, 69, 3; 431--437
2300-1933

Pojawia się w:

International Journal of Electronics and Telecommunications

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 45.

Tytuł:

Algorytmy kolejkowania : algorytm RED (Random Early Detection)
Queueing algorithms : algorithm RED (Random Early Detection)

Autorzy:

Iljaszewicz, Paweł

Powiązania:

https://bibliotekanauki.pl/articles/131935.pdf

Data publikacji:

2018

Wydawca:

Wrocławska Wyższa Szkoła Informatyki Stosowanej Horyzont

Tematy:

aktywne zarządzanie kolejkami
AQM
metody kolejkowania
algorytm RED
przepustowość sieci
active queue management
queuing methods
RED algorithm
network bandwidth

Opis:

Artykuł omawia algorytm Losowego Wczesnego Wykrywania RED (ang. Random Early Detection) pozwalający bramce unikania przeciążeń w sieciach z komutacją pakietów. Brama wykrywa początkowe przeciążenie, obliczając średni rozmiar kolejki. Brama może powiadamiać o przeciążonych połączeniach lub o upuszczeniu pakietów przybywających do bramy, ustawiając bit w nagłówkach pakietów. Kiedy rozmiar średniej kolejki przekracza ustawiony próg, brama opada lub zaznacza każdy przybywający pakiet z pewnym prawdopodobieństwem, gdzie dokładny rozkład prawdopodobieństwa jest funkcją średniego rozmiaru kolejki. Bramki RED utrzymują średnią wielkość kolejki na niskim poziomie, jednocześnie zezwalając na sporadyczne impulsy pakietów w kolejce. Podczas przeciążenia prawdopodobieństwo, że brama powiadamia o konkretnym połączeniu, by zmniejszyć jego okno, jest mniej więcej proporcjonalne do udziału tego w przepustowości przez bramę. Bramki RED są zaprojektowane tak, aby dostarczyć protokół taki jak TCP, przeciążając warstwę transportową. Symulacje sieci TCP / IP są używane do zilustrowania wydajności bramki.
The subject of the study is to present the Random Early Detection (RED) algorithm that allows the gateway to avoid overloading in packet switched networks. The gateway detects the initial overload by calculating the average size of the queue. The gateway can notify about overload connections or by dropping packets arriving at the gate by setting a bit in the packet headers. When the size of the average queue exceeds the set threshold, the gate descends or marks each arriving packet with a certain probability, where the exact probability distribution is a function of the average queue size. RED gates maintain the average queue size at a low level, while allowing occasional packet bursts in the queue. During overload, probability that the gateway informs about a specific connection to reduce its window is more or less proportional to this connection involved in bandwidth through the gate. The RED gateways are designed to provide a protocol such as TCP to overload the transport layer. TCP / IP network simulations are used to illustrate the performance of the gateway.

Źródło:

Biuletyn Naukowy Wrocławskiej Wyższej Szkoły Informatyki Stosowanej. Informatyka; 2018, 8, 1; 4-8
2082-9892

Pojawia się w:

Biuletyn Naukowy Wrocławskiej Wyższej Szkoły Informatyki Stosowanej. Informatyka

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 46.

Tytuł:

Bandwidth and power enhancement in the MEMS-based piezoelectric energy harvester using magnetic tip mass

Autorzy:

Anand, Ashutosh
Pal, Srikanta
Kundu, Sudip

Powiązania:

https://bibliotekanauki.pl/articles/2173519.pdf

Data publikacji:

2022

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

vibration
piezoelectric energy harvester
magnetic tip mass
bandwidth
stress
wibracja
zbieracz energii piezoelektryczny
magnetyczna masa końcówki
przepustowość łącza
stres

Opis:

In this paper, the performance and frequency bandwidth of the piezoelectric energy harvester (PZEH) is improved by introducing two permanent magnets attached to the proof mass of a dual beam structure. Both magnets are in the vicinity of each other and attached in such a way to proof mass of a dual beam so that they create a magnetic field around each other. The generated magnetic field develops a repulsive force between the magnets, which improves electrical output and enhances the bandwidth of the harvester. The simple rectangular cantilever structure with and without magnetic tip mass has a frequency bandwidth of 4 Hz and 4.5 Hz, respectively. The proposed structure generates a peak voltage of 20 V at a frequency of 114.51 Hz at an excitation acceleration of 1 g (g= 9.8 m/s2 ). The peak output power of a proposed structure is 25.5 µW. The operational frequency range of a proposed dual beam cantilever with a magnetic tip mass of 30 mT is from 102.51 Hz to 120.51 Hz, i.e., 18 Hz. The operational frequency range of a dual beam cantilever without magnetic tip mass is from 104.18 Hz to 118.18 Hz, i.e., 14 Hz. There is an improvement of 22.22% in the frequency bandwidth of the proposed dual beam cantilever with a magnetic tip mass of 30 mT than the dual beam without magnetic tip mass.

Źródło:

Bulletin of the Polish Academy of Sciences. Technical Sciences; 2022, 70, 1; e137509, 1--10
0239-7528

Pojawia się w:

Bulletin of the Polish Academy of Sciences. Technical Sciences

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 47.

Tytuł:

The comparison of cohesive soil damping ratios obtained from resonant column tests and designated by the free-vibration decay and half-power bandwidth method
Porównanie wartości współczynnika tłumienia gruntu spoistego z laboratoryjnych badań w kolumnie rezonansowej uzyskanych metodą krzywej gaśnięcia drgań swobodnych i metoda half-power bandwidth

Autorzy:

Sas, W.

Powiązania:

https://bibliotekanauki.pl/articles/40369.pdf

Data publikacji:

2016

Wydawca:

Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie

Tematy:

soil parameter
laboratory test
field test
dynamic parameter
comparison
cohesive soil
resonant column
free-vibration decay
half-power bandwidth method

Opis:

One of the aims of modern laboratory studies is searching for dynamic parameters in a small strain of a soil. The reason behind this trend is the higher level of density of urban areas. City traffic, including trams, cars and subway trains, as well as certain types of construction works, can generate seismic waves, which cause a small strain between the soil and the structure to occur. This may lead to an exceeded limit serviceability state. The three main dynamic parameters of the soil are: Young modulus, shear modulus and damping ratio. Estimation of the cohesive soils damping ratio by two methods, namely free-vibration decay and half-power bandwidth, is the main goal of this article. The author performed his own research on two silty clay specimens in a resonant column. The conducted research show that the damping ratio obtained by using the half-power bandwidth method has significant error margin, which is equal approximately 50-60%, yet the curve shapes are very similar to the ones obtained by using the second method discussed in this paper. In author's opinion, more research on cohesive soils has to be performed in order to introduce necessary corrections to half-power bandwidth equations.
Jednym z celów we współczesnych badaniach laboratoryjnych jest poszukiwanie dynamicznych parametrów gruntu w tzw. małym zakresie odkształcń. Przyczyną takiego stanu rzeczy jest m.in. coraz gęstsza zabudowa miejska, a także ruch miejski, w tym: tramwaje, samochody, pociągi metra i niektóre rodzaje robót budowlanych, które mogą generować powstawanie małych odkształceń na styku grunt - konstrukcja. Takie odkształcenia mogą prowadzić do przekroczenia stanu granicznego używalności konstrukcji. Grunt posiada trzy główne parametry dynamiczne: moduł odkształcalności podłużnej, moduł ścinania oraz współczynnik tłumienia. Głównym celem artykułu było wyznaczenie współczynnika tłumienia gruntu spoistego metodą krzywej gaśnięcia drgań swobodnych i metodą half-power bandwidth. Przeprowadzono badania w kolumnie rezonansowej na dwóch próbka iłu pylastego. Wyniki pokazują, że metoda half-power bandwidth przeszacowuje współczynnik tłumienia w stosunku do metody krzywej gaśnięcia drgań swobodnych od 50 do 60%. Jednak kształty uzyskanych krzywych współczynnika tłumienia w zależności od odkształcenia postaciowego są bardzo podobne. Stwierdzono, że należy przeprowadzić dalsze badania, mające na celu wprowadzenie poprawek do równań metody half-power bandwidth.

Źródło:

Acta Scientiarum Polonorum. Architectura; 2016, 15, 1
1644-0633

Pojawia się w:

Acta Scientiarum Polonorum. Architectura

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 48.

Tytuł:

Utility optimization-based bandwidth allocation for elastic and inelastic services in peer-to-peer networks

Autorzy:

Li, Shiyong
Zhang, Yue
Wang, Yan
Sun, Wei

Powiązania:

https://bibliotekanauki.pl/articles/330690.pdf

Data publikacji:

2019

Wydawca:

Uniwersytet Zielonogórski. Oficyna Wydawnicza

Tematy:

peer-to-peer network
bandwidth allocation
elastic services
inelastic services
utility function
sieć peer-to-peer
alokacja przepustowości
funkcja użyteczności

Opis:

This paper considers reasonable bandwidth allocation for multiclass services in peer-to-peer (P2P) networks, measures the satisfaction of each peer as a customer by a utility function when acquiring one service, and develops an optimization model for bandwidth allocation with the objective of utility maximization. Elastic services with concave utilities are first considered and the exact expression of optimal bandwidth allocation for each peer is deduced. In order to obtain an optimum in distributed P2P networks, we develop a gradient-based bandwidth allocation scheme and illustrate the performance with numerical examples. Then we investigate bandwidth allocation for inelastic services with sigmoidal utilities, which is a nonconvex optimization problem. In order to solve it, we analyze provider capacity provisioning for bandwidth allocation of inelastic services and modify the update rule for prices that service customers should pay. Numerical examples are finally given to illustrate that the improved scheme can also efficiently converge to the global optimum.

Źródło:

International Journal of Applied Mathematics and Computer Science; 2019, 29, 1; 111-123
1641-876X
2083-8492

Pojawia się w:

International Journal of Applied Mathematics and Computer Science

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 49.

Tytuł:

FPGA-based bandwidth selection for kernel density estimation using high level synthesis approach

Autorzy:

Gramacki, A.
Sawerwain, M.
Gramacki, J.

Powiązania:

https://bibliotekanauki.pl/articles/201258.pdf

Data publikacji:

2016

Wydawca:

Polska Akademia Nauk. Czytelnia Czasopism PAN

Tematy:

FPGA
high level synthesis
kernel density estimation
bandwidth selection
plug-in selector
synteza wysokiego poziomu
jądrowy estymator gęstości
wybór pasma informacyjnego

Opis:

Field-programmable gate arrays (FPGA) technology can offer significantly higher performance at much lower power consumption than is available from single and multicore CPUs and GPUs (graphics processing unit) in many computational problems. Unfortunately, the pure programming for FPGA using hardware description languages (HDL), like VHDL or Verilog, is a difficult and not-trivial task and is not intuitive for C/C++/Java programmers. To bring the gap between programming effectiveness and difficulty, the high level synthesis (HLS) approach is promoted by main FPGA vendors. Nowadays, time-intensive calculations are mainly performed on GPU/CPU architectures, but can also be successfully performed using HLS approach. In the paper we implement a bandwidth selection algorithm for kernel density estimation (KDE) using HLS and show techniques which were used to optimize the final FPGA implementation. We are also going to show that FPGA speedups, comparing to highly optimized CPU and GPU implementations, are quite substantial. Moreover, power consumption for FPGA devices is usually much less than typical power consumption of the present CPUs and GPUs.

Źródło:

Bulletin of the Polish Academy of Sciences. Technical Sciences; 2016, 64, 4; 821-829
0239-7528

Pojawia się w:

Bulletin of the Polish Academy of Sciences. Technical Sciences

Dostawca treści:

Biblioteka Nauki

/5

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Skocz do pozycji: 50.

Tytuł:

Szerokość pasma jądrowego estymatora rozkładu pierśnic w drzewostanach olszy czarnej (Alnus glutinosa (L.) Gaertn.) z zachodniej części Kotliny Sandomierskiej
Bandwidth of kernel estimator of DBH distribution in black alder (Alnus glutinosa (L.) Gaertn.) stands from west part of the Sandomierz Basin

Autorzy:

Pogoda, P.
Ochał, W.
Orzeł, S.

Powiązania:

https://bibliotekanauki.pl/articles/985919.pdf

Data publikacji:

2018

Wydawca:

Polskie Towarzystwo Leśne

Tematy:

lesnictwo
dendrometria
drzewa lesne
olsza czarna
Alnus glutinosa
piersnice drzew
rozklad piersnic
estymacja
estymatory jadrowe nieparametryczne
kernel estimator
bandwidth
dbh structure
black alder

Opis:

Set of ‘nonparametric’ methods, that don’t make a priori assumption about functional form of empirical distribution was developed as an alternative to the parametric distribution modeling. The kernel estimators are one of such methods, that can be used to describe the frequency of data representing for example DBH records. Kernel smoothing requires the choice of weighting function and bandwidth also called as smoothing parameter or window. The lack of comprehensive analysis on the applicability of particular bandwidth selection methods to model DBH structure gave an impulse to present investigation aimed at determining value and variability of smoothing parameter in black alder stands. The optimal bandwidth was obtained according to six different variants of plug−in method proposed by Altman and Léger. Presented investigations were based on DBH measurements collected in 163 managed black alder stands aged from 6 to 89 years, growing in the west part of the Sandomierz Basin (S Poland). We measured in total 22,530 black alders, from 48 to 359 in individual stand. Stands were characterized by: age, quadratic mean diameter, basal area, mean height, Reineke’s stand density index and standard deviation of DBH. Smoothing parameter was obtained by means of plug−in method with the pilot bandwidth selected by: Silverman’s rule of thumb (nrd0), Scott’s method (nrd), unbiased cross−validation (ucv), biased cross−validation (bcv), method of Sheather and Jones (sj) and one−stage method of Wand and Jones (onestage). The bandwidth was first obtained to real data, then to 100 bootstrap samples of 5, 10, 15 ... and 100 trees from each stand. Smoothing parameters were characterized by mean and variance. Relationship between values of smoothing parameter and stand characteristics was determined. Finally the influence of sample size on value and variability of bandwidth was assessed. Value and variability of smoothing parameter in black alder stands are determined by stand age, sample size and method of bandwidth choice. There is a close relationship between bandwidth and the mean height (r from 0.75 to 0.83), quadratic mean diameter (r from 0.79 to 0.88) and standard deviation of DBH (r from 0.84 to 0.93). Potentially these stand features can be used to predict smoothing parameter values. Minor changes of bandwidth for samples containing above 50 trees together with persistence of standard error give an objective grounds for defining optimal number of diameters, that are necessary to kernel estimation of DBH distribution.

Źródło:

Sylwan; 2018, 162, 05; 411-421
0039-7660

Pojawia się w:

Sylwan

Dostawca treści:

Biblioteka Nauki

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