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222 results on '"Kempa, Wojciech M."'

1. Queueing Systems with Random Volume Customers and a Sectorized Unlimited Memory Buffer

Author

Tikhonenko Oleg, Ziółkowski Marcin, and Kempa Wojciech M.

Subjects
queueing systems with random volume customers, sectorized memory buffer, total volume vector, laplace and laplace–stieltjes transforms, multi-variate l’hospital rule, Mathematics, QA1-939, Electronic computers. Computer science, QA75.5-76.95
Abstract

In the present paper, we concentrate on basic concepts connected with the theory of queueing systems with random volume customers and a sectorized unlimited memory buffer. In such systems, the arriving customers are additionally characterized by a non-negative random volume vector. The vector’s indications can be understood as the sizes of portions of information of a different type that are located in the sectors of memory space of the system during customers’ sojourn in it. This information does not change while a customer is present in the system. After service termination, information immediately leaves the buffer, releasing its resources. In analyzed models, the service time of a customer is assumed to be dependent on his volume vector characteristics, which has influence on the total volume vector distribution. We investigate three types of such queueing systems: the Erlang queueing system, the single-server queueing system with unlimited queue and the egalitarian processor sharing system. For these models, we obtain a joint distribution function of the total volume vector in terms of Laplace (or Laplace–Stieltjes) transforms and formulae for steady-state initial mixed moments of the analyzed random vector, in the case when the memory buffer is composed of two sectors. We also calculate these characteristics for some practical case in which the service time of a customer is proportional to the customer’s length (understood as the sum of the volume vector’s indications). Moreover, we present some numerical computations illustrating theoretical results.

Published
2021
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2. Intelligent Method of Identifying the Nonlinear Dynamic Model for Helicopter Turboshaft Engines.

Author

Vladov, Serhii, Banasik, Arkadiusz, Sachenko, Anatoliy, Kempa, Wojciech M., Sokurenko, Valerii, Muzychuk, Oleksandr, Pikiewicz, Piotr, Molga, Agnieszka, and Vysotska, Victoria

Subjects
ACCELERATION (Mechanics), ENERGY consumption, DYNAMIC models, TURBINES, TIME management, RECURRENT neural networks
Abstract

This research focused on the helicopter turboshaft engine dynamic model, identifying task solving in unsteady and transient modes (engine starting and acceleration) based on sensor data. It is known that about 85% of helicopter turboshaft engines operate in steady-state modes, while only around 15% operate in unsteady and transient modes. Therefore, developing dynamic multi-mode models that account for engine behavior during these modes is a critical scientific and practical task. The dynamic model for starting and acceleration modes has been further developed using on-board parameters recorded by sensors (gas-generator rotor r.p.m., free turbine rotor speed, gas temperature in front of the compressor turbine, fuel consumption) to achieve a 99.88% accuracy in identifying the dynamics of these parameters. An improved Elman recurrent neural network with dynamic stack memory was introduced, enhancing the robustness and increasing the performance by 2.7 times compared to traditional Elman networks. A theorem was proposed and proven, demonstrating that the total execution time for N Push and Pop operations in the dynamic stack memory does not exceed a certain value O(N). The training algorithm for the Elman network was improved using time delay considerations and Butterworth filter preprocessing, reducing the loss function from 2.5 to 0.12% over 120 epochs. The gradient diagram showed a decrease over time, indicating the model's approach to the minimum loss function, with optimal settings ensuring the stable training. [ABSTRACT FROM AUTHOR]

Published
2024
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4. Time to Start a Crowded Period in a Finite-Buffer Queue with Poisson Input Flow and General Processing Times

Author

Kempa, Wojciech M., Hutchison, David, Editorial Board Member, Kanade, Takeo, Editorial Board Member, Kittler, Josef, Editorial Board Member, Kleinberg, Jon M., Editorial Board Member, Mattern, Friedemann, Editorial Board Member, Mitchell, John C., Editorial Board Member, Naor, Moni, Editorial Board Member, Pandu Rangan, C., Editorial Board Member, Steffen, Bernhard, Editorial Board Member, Terzopoulos, Demetri, Editorial Board Member, Tygar, Doug, Editorial Board Member, Goos, Gerhard, Founding Editor, Hartmanis, Juris, Founding Editor, Dimov, Ivan, editor, Faragó, István, editor, and Vulkov, Lubin, editor

Published
2019
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8. Transient Queueing Delay in a Finite-Buffer Batch-Arrival Model with Constant Repeated Vacations

Author

Kempa, Wojciech M., Marjasz, Rafał, Barbosa, Simone Diniz Junqueira, Series Editor, Chen, Phoebe, Series Editor, Filipe, Joaquim, Series Editor, Kotenko, Igor, Series Editor, Sivalingam, Krishna M., Series Editor, Washio, Takashi, Series Editor, Yuan, Junsong, Series Editor, Zhou, Lizhu, Series Editor, Gaj, Piotr, editor, Sawicki, Michał, editor, Suchacka, Grażyna, editor, and Kwiecień, Andrzej, editor

Published
2018
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9. Time to Buffer Overflow in a Queueing Model with Working Vacation Policy

Author

Kempa, Wojciech M., Kobielnik, Martyna, Barbosa, Simone Diniz Junqueira, Series Editor, Chen, Phoebe, Series Editor, Filipe, Joaquim, Series Editor, Kotenko, Igor, Series Editor, Sivalingam, Krishna M., Series Editor, Washio, Takashi, Series Editor, Yuan, Junsong, Series Editor, Zhou, Lizhu, Series Editor, Gaj, Piotr, editor, Sawicki, Michał, editor, Suchacka, Grażyna, editor, and Kwiecień, Andrzej, editor

Published
2018
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10. Queueing Delay in a Finite-Buffer Model with Failures and Bernoulli Feedback

Author

Kempa, Wojciech M., Kacprzyk, Janusz, Series editor, Pal, Nikhil R., Advisory editor, Bello Perez, Rafael, Advisory editor, Corchado, Emilio S., Advisory editor, Hagras, Hani, Advisory editor, Kóczy, László T., Advisory editor, Kreinovich, Vladik, Advisory editor, Lin, Chin-Teng, Advisory editor, Lu, Jie, Advisory editor, Melin, Patricia, Advisory editor, Nedjah, Nadia, Advisory editor, Nguyen, Ngoc Thanh, Advisory editor, Wang, Jun, Advisory editor, Świątek, Jerzy, editor, Borzemski, Leszek, editor, and Wilimowska, Zofia, editor

Published
2018
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11. On Loss Process in a Queueing System Operating Under Single Vacation Policy

Author

Kempa, Wojciech M., Kacprzyk, Janusz, Series editor, Pal, Nikhil R., Advisory editor, Bello Perez, Rafael, Advisory editor, Corchado, Emilio S., Advisory editor, Hagras, Hani, Advisory editor, Kóczy, László T., Advisory editor, Kreinovich, Vladik, Advisory editor, Lin, Chin-Teng, Advisory editor, Lu, Jie, Advisory editor, Melin, Patricia, Advisory editor, Nedjah, Nadia, Advisory editor, Nguyen, Ngoc Thanh, Advisory editor, Wang, Jun, Advisory editor, Świątek, Jerzy, editor, Borzemski, Leszek, editor, and Wilimowska, Zofia, editor

Published
2018
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13. Departure Counting Process in a Wireless Network Node with Sleep Mode Modelled via Repeated Vacations

Author

Kempa, Wojciech M., Marjasz, Rafał, Barbosa, Simone Diniz Junqueira, Series editor, Chen, Phoebe, Series editor, Filipe, Joaquim, Series editor, Kotenko, Igor, Series editor, Sivalingam, Krishna M., Series editor, Washio, Takashi, Series editor, Yuan, Junsong, Series editor, Zhou, Lizhu, Series editor, Damaševičius, Robertas, editor, and Mikašytė, Vilma, editor

Published
2017
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14. Buffer Overflow Duration in a Model of WSN Node with Power Saving Mechanism Based on SV Policy

Author

Kempa, Wojciech M., Barbosa, Simone Diniz Junqueira, Series editor, Chen, Phoebe, Series editor, Filipe, Joaquim, Series editor, Kotenko, Igor, Series editor, Sivalingam, Krishna M., Series editor, Washio, Takashi, Series editor, Yuan, Junsong, Series editor, Zhou, Lizhu, Series editor, Damaševičius, Robertas, editor, and Mikašytė, Vilma, editor

Published
2017
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15. Erlang Service System with Limited Memory Space Under Control of AQM Mechanizm

Author

Tikhonenko, Oleg, Kempa, Wojciech M., Diniz Junqueira Barbosa, Simone, Series editor, Chen, Phoebe, Series editor, Du, Xiaoyong, Series editor, Filipe, Joaquim, Series editor, Kara, Orhun, Series editor, Kotenko, Igor, Series editor, Liu, Ting, Series editor, Sivalingam, Krishna M., Series editor, Washio, Takashi, Series editor, Gaj, Piotr, editor, Kwiecień, Andrzej, editor, and Sawicki, Michał, editor

Published
2017
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20. Analysis of Transient Virtual Delay in a Finite-Buffer Queueing Model with Generally Distributed Setup Times

Author

Kempa, Wojciech M., Kurzyk, Dariusz, Diniz Junqueira Barbosa, Simone, Series editor, Chen, Phoebe, Series editor, Du, Xiaoyong, Series editor, Filipe, Joaquim, Series editor, Kara, Orhun, Series editor, Kotenko, Igor, Series editor, Liu, Ting, Series editor, Sivalingam, Krishna M., Series editor, Washio, Takashi, Series editor, Czachórski, Tadeusz, editor, Gelenbe, Erol, editor, Grochla, Krzysztof, editor, and Lent, Ricardo, editor

Published
2016
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21. Study on Transient Queueing Delay in a Single-Channel Queueing Model with Setup and Closedown Times

Author

Kempa, Wojciech M., Paprocka, Iwona, Kalinowski, Krzysztof, Grabowik, Cezary, Krenczyk, Damian, Diniz Junqueira Barbosa, Simone, Series editor, Chen, Phoebe, Series editor, Du, Xiaoyong, Series editor, Filipe, Joaquim, Series editor, Kara, Orhun, Series editor, Kotenko, Igor, Series editor, Liu, Ting, Series editor, Sivalingam, Krishna M., Series editor, Washio, Takashi, Series editor, Dregvaite, Giedre, editor, and Damasevicius, Robertas, editor

Published
2016
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22. Transient Solution for Queue-Size Distribution in a Certain Finite-Buffer Model with Server Working Vacations

Author

Kempa, Wojciech M., Kobielnik, Martyna, Diniz Junqueira Barbosa, Simone, Series editor, Chen, Phoebe, Series editor, Du, Xiaoyong, Series editor, Filipe, Joaquim, Series editor, Kara, Orhun, Series editor, Kotenko, Igor, Series editor, Liu, Ting, Series editor, Sivalingam, Krishna M., Series editor, Washio, Takashi, Series editor, Dregvaite, Giedre, editor, and Damasevicius, Robertas, editor

Published
2016
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23. Transient Solution for Queueing Delay Distribution in the GI/M/1/K-type Mode with 'Queued' Waking up and Balking

Author

Kempa, Wojciech M., Woźniak, Marcin, Nowicki, Robert K., Gabryel, Marcin, Damaševicius, Robertas, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Weikum, Gerhard, Series editor, Rutkowski, Leszek, editor, Korytkowski, Marcin, editor, Scherer, Rafał, editor, Tadeusiewicz, Ryszard, editor, Zadeh, Lotfi A., editor, and Zurada, Jacek M., editor

Published
2016
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26. Efficient Management of Material Resources in Low-Carbon Construction.

Author

Mykytyuk, Petro, Brych, Vasyl, Manzhula, Volodymyr, Borysiak, Olena, Sachenko, Anatoliy, Banasik, Arkadiusz, Kempa, Wojciech M., Mykytyuk, Yuliia, Czupryna-Nowak, Aleksandra, and Lebid, Iryna

Subjects
MATERIALS management, CORPORATE profits, CONSTRUCTION & demolition debris, FINANCIAL statements, GROSS margins, CARBON offsetting, ENVIRONMENTAL indicators
Abstract

The sustainable implementation of resources and the transition to low-carbon construction is on the world's daily agenda. This paper describes the development of criteria for the efficient management of material resources in low-carbon construction. Net income, gross profit, balance sheets, and equity are proposed as indicators that serve as criteria for assessing the efficient use of resources. Nonlinear regression models were the methodological basis for the establishment of cause-and-effect relationships of the volume of construction of transport structures. It was established that since construction companies do not purchase materials for storage, the cost of materials for use in low-carbon technological construction work is directly proportional to the cost of construction. The volume of production in the construction industry is determined by construction costs. More efficient use of low-carbon materials reduces cost and construction waste. In this paper, we have established the relationship between the indicator of efficiency for the functioning of the construction enterprises in Ukraine and the use of low-carbon materials for the construction of transport structures. The practical value of the obtained results for low-carbon construction management lies in proving the relationship between the performance indicators of the construction enterprise (net profit, gross profit, output volume, balance sheets, and equity capital) and the use of low-carbon material resources. Our results form the basis for future research into the use of a cost-based model for low-carbon economy transition in municipalities and regions. [ABSTRACT FROM AUTHOR]

Published
2024
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28. TOWARDS A SMART CITY: MODELLING A BIKE-SHARING STATION VIA A QUEUEING LOSS SYSTEM.

Author

KEMPA, Wojciech M. and BANASIK, Arkadiusz

Subjects
SMART cities, DISTRIBUTION (Probability theory), URBAN renewal, CYCLING, MATHEMATICAL models, CONSUMERS
Abstract

Purpose: The article aims to build a mathematical model of a bike-sharing station based on an appropriate queueing system and show the model's usefulness in practice. Design/methodology/approach: In designing the model, constructing a queueing system described by exponential distributions with a finite accumulating buffer was used. The existence of the steady state of the system and the global balance principle were used to obtain analytical results. Findings: The most important analytical results are the stationary probability distribution of the number of rented bikes, the so-called loss probability (the probability that the customer has to resign from sharing due to the lack of bikes), as well as the average (mean) values of the number of rented bikes. Originality/value: The paper fits into the broadly understood trend of research related to the smart city concept. The proposed model may be beneficial in practice when designing specific solutions related to the development of bicycle rental stations. [ABSTRACT FROM AUTHOR]

Published
2023
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29. Performance evaluation of an M/G/n-type queue with bounded capacity and packet dropping

Author

Tikhonenko Oleg and Kempa Wojciech M.

Subjects
aqm algorithms, finite buffer, loss probability, total packet volume, queue-size distribution, Mathematics, QA1-939, Electronic computers. Computer science, QA75.5-76.95
Abstract

A queueing system of the M/G/n-type, n ≥ 1, with a bounded total volume is considered. It is assumed that the volumes of the arriving packets are generally distributed random variables. Moreover, the AQM-type mechanism is used to control the actual buffer state: each of the arriving packets is dropped with a probability depending on its volume and the occupied volume of the system at the pre-arrival epoch. The explicit formulae for the stationary queue-size distribution and the loss probability are found. Numerical examples illustrating theoretical formulae are given as well.

Published
2016
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30. Time-Dependent Behavior of Queueing Delay in GI/M/1/K-type Model with N-policy: Analytical Study with Applications to WSNs

Author

Kempa, Wojciech M., Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Kobsa, Alfred, editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Weikum, Gerhard, editor, Sericola, Bruno, editor, Telek, Miklós, editor, and Horváth, Gábor, editor

Published
2014
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31. On Applying Evolutionary Computation Methods to Optimization of Vacation Cycle Costs in Finite-Buffer Queue

Author

Woźniak, Marcin, Kempa, Wojciech M., Gabryel, Marcin, Nowicki, Robert K., Shao, Zhifei, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Kobsa, Alfred, editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Weikum, Gerhard, editor, Goebel, Randy, editor, Tanaka, Yuzuru, editor, Wahlster, Wolfgang, editor, Siekmann, Jörg, editor, Rutkowski, Leszek, editor, Korytkowski, Marcin, editor, Scherer, Rafał, editor, Tadeusiewicz, Ryszard, editor, Zadeh, Lotfi A., editor, and Zurada, Jacek M., editor

Published
2014
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33. Output Process in Batch-Arrival Queue with N-Policy and Multiple Vacations

Author

Kempa, Wojciech M., Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Dudin, Alexander, editor, and De Turck, Koen, editor

Published
2013
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34. Genetic Cost Optimization of the GI/M/1/N Finite-Buffer Queue with a Single Vacation Policy

Author

Gabryel, Marcin, Nowicki, Robert K., Woźniak, Marcin, Kempa, Wojciech M., Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Goebel, Randy, editor, Siekmann, Jörg, editor, Wahlster, Wolfgang, editor, Rutkowski, Leszek, editor, Korytkowski, Marcin, editor, Scherer, Rafał, editor, Tadeusiewicz, Ryszard, editor, Zadeh, Lotfi A., editor, and Zurada, Jacek M., editor

Published
2013
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35. The Generalization of AQM Algorithms for Queueing Systems with Bounded Capacity

Author

Tikhonenko, Oleg, Kempa, Wojciech M., Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Wyrzykowski, Roman, editor, Dongarra, Jack, editor, Karczewski, Konrad, editor, and Waśniewski, Jerzy, editor

Published
2012
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36. The Virtual Waiting Time in a Finite-Buffer Queue with a Single Vacation Policy

Author

Kempa, Wojciech M., Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Al-Begain, Khalid, editor, Fiems, Dieter, editor, and Vincent, Jean-Marc, editor

Published
2012
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37. Departure Process in Finite-Buffer Queue with Batch Arrivals

Author

Kempa, Wojciech M., Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Al-Begain, Khalid, editor, Balsamo, Simonetta, editor, Fiems, Dieter, editor, and Marin, Andrea, editor

Published
2011
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44. A finite-buffer queue with a single vacation policy: An analytical study with evolutionary positioning

Author

Woźniak Marcin, Kempa Wojciech M., Gabryel Marcin, and Nowicki Robert K.

Subjects
finite-buffer queue, evolutionary strategy, object positioning, queueing system, busy period, idle time, single vacation, Mathematics, QA1-939, Electronic computers. Computer science, QA75.5-76.95
Abstract

In this paper, application of an evolutionary strategy to positioning a GI/M/1/N-type finite-buffer queueing system with exhaustive service and a single vacation policy is presented. The examined object is modeled by a conditional joint transform of the first busy period, the first idle time and the number of packets completely served during the first busy period. A mathematical model is defined recursively by means of input distributions. In the paper, an analytical study and numerical experiments are presented. A cost optimization problem is solved using an evolutionary strategy for a class of queueing systems described by exponential and Erlang distributions.

Published
2014
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