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Abstract

In the present paper, we investigate a multi-server Erlang queueing system with heterogeneous servers, non-homogeneous customers and limited memory space. The arriving customers appear according to a stationary Poisson process and are additionally characterized by some random volume. The service time of the customer depends on his volume and the joint distribution function of the customer volume and his service time can be different for different servers. The total customers volume is limited by some constant value. For the analyzed model, steady-state distribution of number of customers present in the system and loss probability are calculated. An analysis of some special cases and some numerical examples are attached as well.

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Authors and Affiliations

O. Tikhonenko
M. Ziółkowski
M. Kurkowski
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Abstract

This study aims at developing a machine learning based classification and regression-based models for slope stability analysis. 1140 different cases have been analysed using the Morgenstern price method in GeoSlope for non-homogeneous cohesive slopes as input for classification and regression-based models. Slope failures presents a serious challenge across many countries of the world. Understanding the various factors responsible for slope failure is very crucial in mitigating this problem. Therefore, different parameters which may be responsible for failure of slope are considered in this study. 9 different parameters (cohesion, specific gravity, slope angle, thickness of layers, internal angle of friction, saturation condition, wind and rain, blasting conditions and cloud burst conditions) have been identified for the purpose of this study including internal, external and factors representing the geometry of the slope has been included. Four different classification algorithms namely Random Forest, logistic regression, Support Vector Machine (SVM), and K Nearest Neighbor (KNN) has been modelled and their performances have been evaluated on several performance metrics. A similar comparison based on performance indices has been made among three different regression models Decision tree, random forest, and XGBoost regression.
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Authors and Affiliations

Sudhir Kumar Singh
1
ORCID: ORCID
Debashish Chakravarty
1
ORCID: ORCID

  1. Indian Institute of Technology, Kharagpur, India
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Abstract

Heat exhaustion of mining environments can cause a significant threat to human health. The existing cooling strategies for the mine face aim to cool the whole face. However, the necessary cooling space for the face is small, with a considerable amount of energy for cooling being wasted. Necessary cooling space is a space occupied by the workers in the face. This study proposed to build a non-homogeneous thermal environment for cost-effective energy savings in the face. An inlet air cooler was laid out in the intake airway to cool the whole face to some extent, and the tracking air cooler was designed to track the worker who constantly moved to improve the thermal environment. The cooling load and air distribution for this cooling strategy were investigated. In addition, the airflow in the face was solved numerically to estimate the cooling effect. The results revealed that an average energy saving of approximately 35% could be achieved. The thermal environment of the necessary cooling space within at least 10 m was significantly improved. This cooling strategy should be taken into account in mine cooling.
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Bibliography

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Authors and Affiliations

Xian Li
1
ORCID: ORCID
Yaru Wu
1
ORCID: ORCID
Yunfei Zhang
2
ORCID: ORCID

  1. Linyi University, School of Civil Engineering and Architecture, Linyi 276000, P.R. China
  2. Hohai University, College of Civil and Transportation Engineering, Nanjing 210098, P.R. China
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Abstract

In the paper, we investigate queueing system M/G/∞ with non–homogeneous customers. As non–homogenity, we mean that each customer is characterized by some arbitrarily distributed random volume. The arriving customers appear according to a stationary Poisson process. Service time of a customer is proportional to his volume. The system is unreliable what means that all its servers can break simultaneously and then the repair period goes on for random time having an arbitrary distribution. During this period, customers present in the system and arriving to it are not served. Their service continues immediately after repair period termination. Time intervals of the system in good repair mode have an exponential distribution. For such system, we determine steady–state sojourn time and total volume of customers present in it distributions. We also estimate the loss probability for the similar system with limited total volume. An analysis of some special cases and some numerical examples are attached as well.

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Authors and Affiliations

O. Tikhonenko
M. Ziółkowski
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Abstract

The aim of the work was to develop a prioritizing and scheduling method to be followed in small and medium-sized companies operating under conditions of non-rhythmic and nonrepeatable production. A system in which make to stock, make to order and engineer to order (MTS, MTO and ETO) tasks are carried out concurrently, referred to as a non-homogenous system, has been considered. Particular types of tasks have different priority indicators. Processes involved in the implementation of these tasks are dependent processes, which compete for access to resources. The work is based on the assumption that the developed procedure should be a universal tool that can be easily used by planners. It should also eliminate the intuitive manner of prioritizing tasks while providing a fast and easy to calculate way of obtaining an answer, i.e. a ready plan or schedule. As orders enter the system on an ongoing basis, the created plan and schedule should enable fast analysis of the result and make it possible to implement subsequent orders appearing in the system. The investigations were based on data from the non-homogenous production system functioning at the Experimental Plant of the Łukasiewicz Research Network – Institute of Ceramics and Building Materials, Refractory Materials Division – ICIMB. The developed procedure includes the following steps: 1 – Initial estimation of resource availability, 2 – MTS tasks planning, 3 – Production system capacity analysis, 4 – ETO tasks planning, 5 – MTO orders planning, 6 – Evaluation of the obtained schedule. The scheduling procedure is supported by KbRS (Knowledge-based Rescheduling System), which has been modified in functional terms for the needs of this work assumption.
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Authors and Affiliations

Bożena Skołud
1
Agnieszka Szopa
2
Krzysztof Kalinowski
1

  1. Silesian University of Technology, Faculty of Mechanical Engineering, Poland
  2. The Institute of Ceramics and Building Materials, Refractory Materials Division in Gliwice, Poland

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