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Abstract

Various intelligent transportation systems are proposed in different forms of wireless communication technologies. Recently, the importance of visible light communication and free-space optics has been demonstrated in accomplishing vehicle-to-vehicle and infrastructure-to-vehicle communication systems, due to power efficiency, free licenses, and safety for human health. In this paper, a new hybrid relay system supported by free-space optics/visible light communication with two scenarios is proposed. The first one is that the data are transferred from the source to the relay through a free-space optics communication link and are then directed to the destination through a visible light communication link. The second scenario is that the data are transmitted from the source to the destination passing through two different relays to ensure larger coverage. A 10−6 bit error rate is achieved at a distance of 900 m for the first scenario with a remarkable signal-to-noise ratio of ~25.5 dB, while the largest distance that can be covered by the second scenario is 1200 m with a signal-to-noise ratio of ~30 dB.
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Authors and Affiliations

Suzan M. EL-Garhy
1 2
Ashraf A. M. Khalaf
2
ORCID: ORCID
Moustafa H. Aly
3
ORCID: ORCID
Mohamed Abaza
3
ORCID: ORCID

  1. Electronics and Communications Department, College of Engineering, Higher Technological Institute, Tenth of Ramadan, Egypt
  2. Electronics and Communications Department, Faculty of Engineering, Minia University, Egypt
  3. Electronics and Communications Department, College of Engineering and Technology, Arab Academy for Science Technology and Maritime Transport, Egypt
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Abstract

In the present paper, we analyze the model of a single–server queueing system with limited number of waiting positions, random volume customers and unlimited sectorized memory buffer. In such a system, the arriving customer is additionally characterized by a non– negative random volume vector whose indications usually represent the portions of unchanged information of a different type that are located in sectors of unlimited memory space dedicated for them during customer presence in the system. When the server ends the service of a customer, information immediately leaves the buffer, releasing resources of the proper sectors. We assume that in the investigated model, the service time of a customer is dependent on his volume vector characteristics. For such defined model, we obtain a general formula for steady–state joint distribution function of the total volume vector in terms of Laplace-Stieltjes transforms. We also present practical results for some special cases of the model together with formulae for steady–state initial moments of the analyzed random vector, in cases where the memory buffer is composed of at most two sectors. Some numerical computations illustrating obtained theoretical results are attached as well.
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Authors and Affiliations

Marcin Ziółkowski
1
ORCID: ORCID
Oleg Tikhonenko
2
ORCID: ORCID

  1. Institute of Information Technology, Warsaw University of Life Sciences – SGGW, Poland
  2. Institute of Computer Science, Cardinal Stefan Wyszynski University in Warsaw, Poland
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Abstract

Recently, simultaneous monitoring of process mean and variability has gained increasing attention. By departing from the accurate measurements assumption, this paper investigates the effect of gauge measurement errors on the performance of the maximum generally weighted moving average (Max-GWMA) chart for simultaneous monitoring of process mean and variability under an additive covariate model. Multiple measurements procedure is employed to compensate for the undesired impact of gauge inaccuracy on detection capability of the Max- GWMA chart. Simulation experiments in terms of average run length (ARL) are conducted to assess the power of the developed chart to detect different out-of-control scenarios. The results confirm that the gauge inaccuracy affects the sensitivity of the Max-GWMA chart. Moreover, the results show that taking multiple measurements per item adequately decreases the adverse effect of measurement errors. Finally, a real-life example is presented to demonstrate how measurement errors increases the false alarm rate of the Max-GWMA chart.
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Authors and Affiliations

Saeid Sharafi
1
Mohammad Reza Maleki
2
Ali Salmasnia
3
Reihaneh Mansoor
4

  1. Smart Research Center, Häme University of Applied Sciences, Finland
  2. Industrial Engineering Group, Golpayegan College of Engineering, Isfahan University of Technology, Golpayegan, Iran
  3. Department of Industrial Engineering, Faculty of Engineering, University of Qom, Iran
  4. Department of Industrial Engineering, University of Eyvanekey, Eyvanekey, Iran

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