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Wyświetlanie 1-13 z 13
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:
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:
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
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
Artykuł
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
Artykuł
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
Artykuł
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
Artykuł
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
Artykuł
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
Artykuł
Tytuł:
Performance of variance function estimators for autoregressive time series of order one: asymptotic normality and numerical study
Autorzy:
Borkowski, P.
Mielniczuk, J.
Powiązania:
https://bibliotekanauki.pl/articles/206217.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
autoregressive process
bandwidth
heteroscedasticity
integrated squared error
local linear and local maximum likelihood estimator
difference-based estimator
geometric moment contraction
variance function
volatility
Opis:
We study performance of several conditional variance estimators for an autoregressive time series which include local linear smoothers with various bandwidths, local likelihood and difference-based estimators. In the theoretical part, asymptotic normality of the local linear estimator of variance with no mixing assumptions imposed on the underlying process is proved. Moreover, numerical examples performed reveal that a two-stage local linear smoother with a bandwidth, proposed by Ruppert, Sheather and Wand, used to estimate the regression function and a simple rule of thumb bandwidth for variance estimation performs best for variances without much structure, whereas the bandwidth considered by Fan and Yao works very well for much more variable variances.
Źródło:
Control and Cybernetics; 2012, 41, 2; 415-441
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research of influence of time of reaction of the driver on the calculation of the capacity of the highway
Исследование влияния времени реакции водителя на расчет пропускной способности автотрассы
Autorzy:
Shevtsova, A.
Novikov, I.
Borovskoy, A.
Powiązania:
https://bibliotekanauki.pl/articles/374513.pdf
Data publikacji:
2015
Wydawca:
Politechnika Śląska. Wydawnictwo Politechniki Śląskiej
Tematy:
time of reaction of the driver
bandwidth
site of the road network
traffic regulation
system driver-car-road-environment
highway
throughput highway
czas reakcji kierowcy
pasmo
witryny sieci drogowej
regulacja ruchu drogowego
system kierowca-samochód-droga-środowisko
autostrada
przepustowość autostrady
Opis:
In the work we performed a review of studies of foreign scholars on changing the reaction time of the driver depending on various road conditions, namely the change in the response time when using the traffic light regulation. Earlier by the authors of this article have already been carried out research in the field of throughput of a site of a highway with traffic regulation, which showed that this value depends on the time of reaction of the driver. In this article the estimation of how much bandwidth the highway using different result obtained in the course of analysis, time value of reaction of the driver and is a direct correlation bandwidth from the time of reaction of the driver. The values obtained allow to conclude that taking into account the psycho-physiological characteristics of drivers (response time) will have a significant impact on the throughput and the various methods of organization and reorganization of sections of the road network, implementation of which is used investigated the amount of bandwidth.
В работе выполнен обзор исследований зарубежных ученых по изменению времени реакции водителя в зависимости от различных дорожных условий, а именно изменение времени реакции при использовании светофорного регулирования. Ранее авторами данной статьи уже были проведены исследования в области пропускной способности участка автотрассы при светофорном регулировании, которые показали, что данная величина зависит от времени реакции водителя. В данной статье проведен расчет величины пропускной способности автотрассы при использовании различных, полученных в ходе анализа, значений времени реакции водителя и установлена прямая зависимость пропускной способности от времени реакции водителя. Полученные значения, позволяют сделать вывод о том, что учет психофизиологических характеристик водителей (время реакции) будет оказывать значительное влияние на пропускную способность и различные методы организации и реорганизации участков улично-дорожной сети, при реализации которых используется исследуемая величина пропускной способности.
Źródło:
Transport Problems; 2015, 10, 3; 53-59
1896-0596
2300-861X
Pojawia się w:
Transport Problems
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-13 z 13

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