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1

An IEEE 802.11 MAC Layer Covert Channel Based On Supported Rates

Teca Geovan, Natkaniec Marek

International Journal of Electronics and Telecommunications

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2023

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Vol. 69, No. 2

293--299

EN

Wireless Local Area Networks present several vulnerabilities that are exploited, and as a result, numerous attacks have been developed and used against them. Although countermeasures to detect and eliminate such threats have been created throughout the years, few methods exist to prevent the attacks. IEEE 802.11 covert channels could be considered a candidate to prevent Wi-Fi attacks since they allow secret communication between the client station and the access point without establishing an association. They can be implemented in frames that attackers do not target. This paper presents a new covert channel that prevents Wi-Fi attacks. We also describe metrics, and discuss the performance results of the proposed solution. We show that the new protocol is able to achieve high efficiency of operation.

2

Application of machine learning ensemble models for rainfall prediction

Ahmadi Hasan, Aminnejad Babak, Sabatsany Hojat

Acta Geophysica

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2023

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Vol. 71, no. 4

1775--1786

EN

Practical information can be drawn from rainfall for making long-term water resources management plans, taking flood mitigation measures, and even establishing proper irrigation systems. Given that a large amount of data with high resolution is required for physical modeling, this study proposes a new standalone sequential minimal optimization (SMO) regression model and develops its ensembles using Dagging (DA), random committee (RC), and additive regression (AR) models (i.e., DA-SMO, RC-SMO, and AR-SMO) for rainfall prediction. First, 30-year monthly data derived from the year 1988 to 2018 including evaporation, maximum and minimum temperatures, maximum and minimum relative humidity rates, sunshine hours, and wind speed as input and rainfall as the output were acquired from a synoptic station in Kermanshah, Iran. Next, based on the Pearson correlation coefficient (r-value) between input and output variables, different input scenarios were formed. Then, the dataset was separated into three subsets: development (1988–2008), calibration (2009–2010), and validation (2011–2018). Finally, the performance of the developed algorithms was validated using different visual (scatterplot and boxplot) and quantitative (percentage of BIAS, root mean square error, Nash–Sutcliffe efficiency, and mean absolute error) metrics. The results revealed that minimum relative humidity had the greatest effect on rainfall prediction. The most effective input scenario featured all the input variables except for wind speed. Our findings indicated that the DA-SMO ensemble algorithm outperformed other algorithms.

3

Monitoring the performance of a ship’s main engine based on big data technology

Liang Meng, Chen Mingzhi

Polish Maritime Research

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2022

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nr 3

128--140

EN

Under the recent background of ‘Green Shipping’ and rising fuel prices, it is very important to reduce the fuel consumption rate of ships, which is directly affected by the performance of the main engine. A reasonable maintenance schedule can optimise the performance of the main engine. However, a traditional maintenance schedule is based on the navigation distance and time, ignoring many other factors, such as a harsh working environments and frequently changing operating conditions, which will lead to faster performance degradation. In this study, a real-time evaluation method combing big data of ship energy efficiency with physics-based analysis is proposed to judge the degradation of main engine performance and assist in determining the maintenance schedule. Firstly, based on the developed ship energy efficiency big data platform, the distribution statistics and comparison of different operating states are carried out. Gaussian mixture model (GMM) and Density-Based Spatial Clustering of Applications with Noise (DBSCAN) are used to cluster the data and the high-density data areas are obtained as the analysis points. Then, the data of the analysis points are polynomial fitted, by the least square method, to obtain the propulsion characteristics curves, load characteristic curves, and speed characteristic curves, which can be used to observe the performance degradation of the main engine. The results show that this method can effectively monitor the degradation degree of the main engine performance, and is of great significance to fuel efficiency improvements and greenhouse gas (GHG) emissions reduction.

4

Efficiency of project management in higher education establishments on the example of Gdynia Maritime University

Kizielewicz Joanna, Winiarska Magdalena, Skrzeszewska Katarzyna, Szelągowska-Rudzka Katarzyna

Management

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2022

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Vol. 26, no. 1

164--188

EN

Project management is sufficiently described in the source literature. However, numerous published scientific works refer mainly to examples of good practice in project management in business entities, and unfortunately higher education establishments (HEE) are marginally analysed. Therefore, the analyses defined in study aim to evaluate the performance indicators of project management in universities, on the example of Gdynia Maritime University. In the studies the research in action method was applied as well as the technique of direct interview with project or department managers involved in the project implementation. The analyses covered selected projects that were implemented at the University between 2017 and 2021. Moreover, research questions were formulated, i.e., 1) Which indicators are used to assess the efficiency of project management at HEE?, 2) Does the surveyed HEE analyse the project management efficiency assessment? In order to conduct the study, the Author’s indicators were proposed to assess the efficiency of process management during the implementation of projects in HEE and these were applied in the analysis presented in this article. It was found that the surveyed university does not apply indicators to assess the efficiency of project management. Whereas the use fulness of indicators proposed by the Authors to study the efficiency of project management was confirmed by calculations performed. On these grounds, the Authors recommend the University authorities should consider implementing these indicators.

PL

Zarządzanie projektami jest solidnie opisane w literaturze przedmiotu. Jednakże liczne opublikowane prace naukowe odnoszą się głównie do przykładów dobrych praktyk w zarządzaniu projektami w podmiotach gospodarczych, a niestety jednostki szkolnictwa wyższego są traktowane marginalnie. Celem badań w niniejszej pracy jest zatem ocena wskaźników efektywności zarządzania projektami w uczelniach wyższych, przy czym jako przykład wybrano Uniwersytet Morski w Gdyni. W badaniach posłużono się metodą obserwacji uczestniczącej oraz techniką wywiadu bezpośredniego z kierownikami projektów lub działów zaangażowanych w realizację projektów. Badaniom poddano wybrane projekty, które realizowane były na Uczelni w okresie 2017-2021. Sformułowano również pytania badawcze tj. 1) Jakie wskaźniki wykorzystywane są do oceny efektywności zarządzania projektami w HEE?, 2) Czy w badanej HEE prowadzone są analizy oceny efektywności zarządzania w projektach? W celu przeprowadzenia badań zaproponowane zostały autorskie wskaźniki oceny efektywności zarządzania przy realizacji projektów na uczelniach i zastosowano je w analizie zaprezentowanej w artykule. Stwierdzono, że badana uczelnia nie stosuje wskaźników oceny efektywności zarządzania projektami. Natomiast użyteczność tych zaproponowanych przez Autorki do badania efektywności zarządzania projektami potwierdziły przeprowadzone obliczenia. Na ich podstawie Autorki rekomendują

5

Porównanie wydajności szkieletów programistycznych mapowania obiektowo-relacyjnego dostępnych w języku Java

Pitera Jakub Benedykt, Połeć Mateusz, Kozieł Grzegorz

Journal of Computer Sciences Institute

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2022

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Vol. 22

59--65

PL

Artykuł poświęcono wykonaniu analizy porównawczej wybranych narzędzi mapowania obiektowo-relacyjnego. Jego celem jest pomoc architektomoprogramowania w określeniu, która z analizowanych bibliotek będzie optymalnym wyborem do użycia w określonym projekcie.Celem artykułu jest ocena bibliotek Hibernate ORM, EclipseLink, Apache OpenJPAoraz DataNucleus pod kątem teoretycznym oraz praktycznym. Każde z badanych narzędzi opisane zostało według kryteriów pozwalających na wyodrębnienie najważniejszych cech mających wpływ na komunikację z relacyjnymi bazami danych. Cechy te następnie zostałyporównane na poziomie praktycznym poprzez zbadanie zachowania aplikacji testowych. Pod względem wydajnościowym, najlepsza okazała się biblioteka Apache OpenJPA, jednak pod względem konfiguracji i dostępności znacznie odstępuje od innych bibliotek. Spowodowane było tonieintuicyjną konfiguracją oraz ubogą dokumentacją technologii. Pod tym względem zdecydowanie górowała biblioteka Hibernate dziękipełnej kompatybilności ze szkieletem programistycznym Spring, intuicyjnej konfiguracji oraz bogatej dokumentacji i wsparcia przez obszerną społeczność korzystających z niej programistów.

EN

The paper concerns a performance evaluation of selected object-relational mapping tools. This work is intended to assist software architects in determining which of the analyzed libraries will be the optimal choice for use in a specific project. The work includes the comparison of Hibernate ORM, EclipseLink, Apache OpenJPA and DataNucleus libraries from the theoretical and practical point of view. Each of the examined tools has been described according to criteria allowing to distinguish the most important features influencing communication with relational databases. These features will then be compared on a practical level by examining the behavior of the test applications. In terms of performance, the Apache OpenJPA library turned out to be the best, but in terms of configuration and availability it significantly differs from other libraries. This was caused by an unintuitive configuration and poor documentation of the technology. In this respect, the Hibernate library definitely dominated thanks to full compatibility with the Spring programming framework, intuitive configuration as well as rich documentation and support by the extensive community of programmers using it.

6

An SFA-HMM performance evaluation method using state difference optimization for running gear systems in high-speed trains

Cheng Chao, Wang Meng, Wang Jiuhe, Shao Junjie, Chen Hongtian

International Journal of Applied Mathematics and Computer Science

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2022

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Vol. 32, no. 3

389--402

EN

The evaluation of system performance plays an increasingly important role in the reliability analysis of cyber-physical systems. Factors of external instability affect the evaluation results in complex systems. Taking the running gear in high-speed trains as an example, its complex operating environment is the most critical factor affecting the performance evaluation design. In order to optimize the evaluation while improving accuracy, this paper develops a performance evaluation method based on slow feature analysis and a hidden Markov model (SFA-HMM). The utilization of SFA can screen out the slowest features as HMM inputs, based on which a new HMM is established for performance evaluation of running gear systems. In addition to directly classical performance evaluation for running gear systems of high-speed trains, the slow feature statistic is proposed to detect the difference in the system state through test data, and then eliminate the error evaluation of the HMM in the stable state. In addition, indicator planning and status classification of the data are performed through historical information and expert knowledge. Finally, a case study of the running gear system in high-speed trains is discussed. After comparison, the result shows that the proposed method can enhance evaluation performance.

7

Upgradation of Wool Scouring Plant for Efficient Wastewater Treatment

Awchat Ganesh Deoraoji

Ecological Engineering & Environmental Technology

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2022

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Vol. 23, iss. 1

11--18

EN

The paper emphasized the manufacturing processes of the wool scouring plant, study of the wastewater characteristics generated from the plant in the laboratory, performance evaluation of the existing effluent treatment plant (ETP) with the present pollution load. On their basis, an approach and flow sheet for the treatment of wastewater obtained from wool scouring is suggested to improve the performance and treatment of wastewater.

8

Design and Performance Evaluation of Protective Clothing for Emergency Rescue

Zhang Haitang, Zheng Qing, Ke Ying, Wang Hongfu, Wang Min, Ye Yuanli

Autex Research Journal

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2022

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Vol. 22, no. 1

1--10

EN

Protective clothing is very important to guarantee the safety of emergency rescuers. And proper construction design of clothing will improve the rescue efficacy. This study developed a new set of emergency rescue protective clothing (NC) and evaluated its performance. Clothing fit test, freedom of movement, and rationality of pocket tests were conducted. The results showed that the amount of slippage at the hem, waist of pants, and leg opening of NC has been greatly reduced. The NC had provided better cloth fit and dynamic comfort. The storage capacity of the pockets had been increased, the position and angle design of the pocket made it easier to take and keep the rescue tools.

9

Towards digital twin-driven performance evaluation methodology of FMS

Bocewicz Grzegorz, Wójcik Robert, Sitek Paweł, Banaszak Zbigniew

Applied Computer Science

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2022

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Vol. 18, no 3

5--18

EN

The paper presents a method of automated modelling and performance evaluation of concurrent production flows carried out in Flexible Manufacturing Systems. The method allows for quick assessment of various variants of such systems, considering their structure and the organization of production flow of possible ways of their implementation. Its essence is the conditions imposed on the designed model, limiting the space of possible variants of the production flow only to deadlock-free variants. The practical usefulness of the model implemented in the proposed method illustrates the example, which describes the simultaneous assessment of alternative variants of the flexible machining module's structure and the planned multi-assortment production. The ability of the method to focus on feasible solutions offers attractive perspectives for guiding the Digital Twin-like scenario in situations caused by the need to change the production flow.

10

An Active Broadcast System for Safety-Oriented Facilities in Decentralized TDMA Assisted VANETs

Tamilarasi A., Sivabalaselvamani D., Rahunathan L., Adhithyaa N.

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 1

122--128

EN

In data link layer for vehicular Ad hoc Network, a twelve digit access control mechanism is available. That is Medium Access Control (MAC) protocol should be able to accommodate a wide variety of safety oriented real time applications in vehicular ad-hoc networks (VANETs). The most important aspect of those applications is the transmission safety messages in which we call it as Basic Safety Messages (BSMs) through V2V and V2I systems. When traffic thickness is heavy, a scheduled transfer of BSMs places a large load on the VANETs’ stack, compromising network compatibility and performance. This article addresses a Decentralized TDMA-based framework for regulating transmission boundaries in VANETs to increase the potential of BSM transmissions. The transmitting effects are often low, but they do not reduce the consciousness of the nodes in close proximity. Consolidating packet collisions are often observed and cutoff at that time by a concerted effort among the nodes. Our procedures will provide a profitable and efficient BSM broadcasting, according to the simulation results.

11

Development and Performance Evaluation of a Pulverizer for Plantain Flour Process Plant

Olutomilola Emmanuel Olatunji, Ayodeji Sesan Peter, Adeyeri Michael Kanisuru, Fagbemi Tayo Nathaniel

Production Engineering Archives

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2021

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Vol. 27, Iss. 3

223--231

EN

Diabetes, adjudged a risk factor for coronavirus infectious disease 2019 (COVID-19), can be managed through consumption of plantain and its associated products. Plantain is usually processed into flour and other storable/value-added products due to its very short shelf-life. To process unripe plantain pulps into flour, there is a need for size reduction after drying. This paper presents the development and performance evaluation of a size reduction unit for pulverizing, sieving and conveying material to the next processing stage in a plantain flour process plant. Its model was developed using solidworks application software. After design analysis, the model was simulated to establish its suitability/adequacy for fabrication. The pulverizer was fabricated using locally available materials. Its performance evaluation gave 400kg/h throughput, 96% crushing efficiency and 96% efficiency based on the required particle size. The average particle size of flour obtained was 236μm using 500μm screen. Effect of cyclone control-valve on the pulverizer’s overall efficiency was also investigated by allowing it to operate when the valve was completely closed, partially closed and fully opened. It was observed that the control-valve’s positions significantly influenced the machine’s performance/efficiency. It can thus be inferred that the position of cyclone control-valve has significant effect on a pulverizer’s efficiency/performance. Hence, leaving control-valve fully opened during operation would help a pulverizer perform with optimum efficiency, as the pulverizer was able to convey material, efficiently in that position, to the next processing stage during performance evaluation.

12

Performance evaluation model and algorithm of green supply chain management based on sustainable computing

He Chao

Ecological Chemistry and Engineering. S

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2021

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Vol. 28, nr 4

499--512

EN

How to facilitate collaborative development between the enterprise and the environment under the dual constraints of resources and the environment is the focus of today's green supply chain management system research. Through the performance evaluation of the green supply chain, we can understand the operation of the whole supply chain and its shortcomings, provide a basis for improving related processes, and have important practical significance for improving the competitiveness and protection of its products. First of all, by summarising and analysing the research status of sustainable supply chain management in different countries, the research idea and overall background of this paper are proposed. It discusses the theory of sustainable supply chain management and the performance evaluation system and calculation types of sustainable supply chain management. Finally, the relative weight of each index is determined based on the sustainability calculation method, and then the decentralisation degree of the index is constructed. During this period, the fuzzy comprehensive evaluation method is used to evaluate the performance of sustainable supply chain, conduct case analysis and summary, and evaluate the performance of green supply chain component in economic, social, environmental and other aspects. In this paper, representative companies are selected as examples to evaluate their green supply chain management performance, and the evaluation algorithm is studied based on sustainable calculation method. The results show that a reasonable and effective evaluation of the enterprise performance of green supply chain management and a sustainable algorithm study can effectively identify potential problems in the operation of the company and improve the overall operation of the company at this stage.

13

Experimental performance characterization and economic efficiency of 16.28 kWp grid-tied PV systems in semi-arid climate

Khennane Messaouda Benbitour, Boughali Slimane, Bechki Djamel, Zaghba Layachi, Fezzani Amor, Mahammed Idriss Hadj

Diagnostyka

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2021

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Vol. 22, No. 2

53--65

EN

The study of the paper aims to present a solar power plant performances and economic benefits of 16.28 kWp grid-tied solar PV systems under the real outdoor conditions of Ghardaïa, located in semi-arid area of the Algeria desert. The main goal of this study is to investigate the effectiveness, suitability, feasibility and reliably of these plants on the level of desert areas and under the influence of harsh conditions (desert environment) in the first part. In the second part, the contribution of solar PV plant to conventional networks in the arid and semi-arid environment to assess the rate of integration. Based on experimental measurement data, the paper also shows economic benefits of three photovoltaic plants. It was found that from the first January to last August 2019, the total produced energy by all PV arrays was 171.422 MWh which supplied to the internal grid and while, the consumed energy by the URAER unit was 159,094 kWh. Approximately 10, 95 % of the 159,094 MWh energy consumed in the whole year is provided from the generated PV solar energy that is 17,422 MWh. The total energy fed to the internal grid has grown from 27 MWh in 05/04/2018 to a maximum of 67.28 MWh recorded in 31/10/2019. The rate of integration of solar energy by all PV arrays in the internal network of the URAER varied between 6, 60% in January and 22, 96% in April. The integration of this renewable energy generation into the local grid in the URAER unit considered satisfactory over this period of operation. From the first January to last August 2019, the cost of electrical energy produced by solar plants is 2090,64 euro(277706,68 Algerian dinars) while the cost of energy consumed by the Applied Research Unit in renewable energies is 4772,82 euro(664853,826 Algerian dinars).

14

Ocular artifact elimination from electroencephalography signals: A systematic review

Ranjan Rakesh, Chandra Sahana Bikash, Kumar Bhandari Ashish

Biocybernetics and Biomedical Engineering

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2021

|

Vol. 41, no. 3

960--996

EN

Electroencephalography (EEG) is the signal of intrigue that has immense application in the clinical diagnosis of various neurological, psychiatric, psychological, psychophysiological, and neurocognitive disorders. It is significantly crucial in neural communication, brain-computer interface, and other practical tasks. EEG signal is exceptionally susceptible to artifacts, which are external noise signals originated from non-cerebral regions. The interference of artifacts in EEG signals can potentially affect the original recorded EEG signal quality and pattern. Therefore, artifact removal from EEG signal is critically important before applying it to a specific task for accurate outcomes. Researchers have proposed numerous techniques to remove various artifacts present in the contaminated EEG signal. However, neither optimum method nor criterion stands standard for endorsement of clinically recorded EEG signals. Therefore, the research related to artifact elimination from EEG signal is challenging and perplexing task. This paper attempts to give an extensive outline of the advancement in methodologies to eliminate one of the most common artifacts, i.e., ocular artifact. It is anticipated that the study will enlighten the researchers on all the existing ocular artifact elimination techniques with a validated simulation model on the recorded EEG signal. In future advancements, Standard norms in artifact elimination techniques are expected to diminish the neurologist’s load by substantiating the clinical diagnosis after gaining correct information from artifact-free EEG signals.

15

Synthesis of Natural Phenolic Compound Contained Alkaline Phenolic Foundry Resin and Its Performance Evaluation on Casting

Güvendik A. E., Ay Kadir

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 2

46--56

EN

In foundry, metal casting can be done with various methods. One of the most important methods preferred around the world is sand casting. Ester curable alkaline phenolic resins have produced to make sand molds by No-bake systems. They must have specific properties to make sand casting efficient and reliable. Production of these resins depends on some fossil raw-materials like phenol. To investigate more sustainable and green resin synthesis method, lots experiment have been done by substitution of phenol with renewable alternative phenolic materials like resorcinol, lignosulphonates and tannic acid and its derivatives. Different properties of resins were produced with competitive performance with the market product, ÇKE Alfanol A 72 No-Bake Resin. Without loss of performance, calcium lignosulfonate was used in polymer synthesis at the rate of 15% instead of phenol. On the other hand, the reaction in which lignin and resorcinol were combined instead of phenol by reducing it by 25% gave better results in terms of mechanical and thermal properties. Thermal properties were investigated for resorcinol and lignin modified resins by using TGA-DSC and mechanical performance of cured sand core sample were tested by Simpson Sand Strength Testing Machine as compression strength as N/cm2. After laboratory testing casting performance of new resins are compared with two different companies’ resins in steal casting demo. Experimental results were matched with casting trail and no defect was detected.

16

Modeling and Performance Evaluation of an Electromagnetic Voltage Regulator via Series Compensation

Brito Vinícius Henrique Farias, Oliveira José Carlos de, Santilio Fabricio Parra

Transactions on Environment and Electrical Engineering

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2020

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Vol. 4, No. 1

12--17

EN

Although there currently exists a wide range of voltage regulators that are commercially available, the search for devices with a simpler physical design remains the focus of research studies. Following this line, an electromagnetic voltage regulator (EVR) arrangement has been proposed. The EVR is constituted of an autotransformer that supplies, via discrete taps, a series transformer that injects voltage for regulating the feeder voltage. Even though its operating principle is shown as being similar to that of other devices on the market, the physical arrangement and operating strategy of EVR show novelties which result in properties such as: economic attractiveness, constructive simplicity, and operational reliability. Moreover, when installing voltage regulators, efficacy studies must be carried out to optimize equipment design. In this context, this paper aims at evaluating the factors that influence the effectiveness of the EVR in restoring voltage variations according to the determinations imposed by regulatory agencies. The ultimate goal of this study is to determine the voltage deviation range that the EVR is able to restore. To achieve this goal, a mathematical modeling of the EVR is given and study cases are computationally carried out to investigate its performance when connected to a typical distribution feeder.

17

Optimisation of decision-making process in industrial robot selection

Kangru Tavo, Riives Jüri, Otto Tauno, Kuts Vladimir, Moor Madis

Journal of Machine Engineering

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2020

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Vol. 20, No. 1

70--81

EN

The successful selection process of industrial robots (IRs) for today’s Cyber-Physical Systems is an important topic and there are different possibilities to solve the task. The primary task is to estimate the existing IR selection systems according to the suitability analysis and to highlight the main positive features and problematic areas. The objective of the reverse task is to carry out the sensitivity analysis of the existing robot-based manufacturing systems. The matching of these two approaches helps decision makers to develop the main principles of IR selection in today’s multidimensional and fast-changing economic world.

18

Design of multifunction simulator for engine room personnel training

Ivanov Artem, Kolosov Igor, Danyk Vadim, Voronenko Sergey, Lebedenko Yurii, Rudakova Hanna

Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska

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2020

|

T. 10, nr 2

62--69

EN

International requirements for improving energy efficiency and environmental protection and the necessary goals for their implementation in the marine industry are an actual problem. To integrate state-of-the-industry technologies and marine specialists education, the training complex is proposed. It is based on the platform of a hardware-software complex with the ability to integrate training equipment, simulators and software. That makes such a training complex multitask, universal, and flexible in achieving a variety of tasks and goals. The complex also implements high-quality education and training of marine specialists, conducting research after processing working out the results of engineering modelling of structural, thermal power, hydraulic, electrical, electronic, multi-physical and other solutions. The need to use the training complex allows us to form the necessary competence of the engine team personnel, develop methods and criteria for assessing competence, evaluate and demonstrate practical skills.

PL

Międzynarodowe wymogi dotyczące poprawy efektywności energetycznej i ochrony środowiska oraz cele niezbędne do ich wdrożenia w przemyśle morskim stanowią aktualny problem. W celu zintegrowania najnowocześniejszych technologii i kształcenia specjalistów z branży morskiej proponuje się utworzenie kompleksu szkoleniowego. Jest on oparty na platformie kompleksu sprzętowo-programowego z możliwością integracji sprzętu szkoleniowego, symulatorów i oprogramowania. To sprawia, że taki kompleks jest wielozadaniowy, uniwersalny i elastyczny w realizacji różnorodnych zadań i celów. Ponadto kompleks realizuje wysokiej jakości kształcenie i szkolenie specjalistów morskich, prowadząc badania po opracowaniu wyników modelowania inżynierskiego rozwiązań konstrukcyjnych, cieplnych, hydraulicznych, elektrycznych, elektronicznych, i innych. Wykorzystanie kompleksu szkoleniowego pozwala na kształtowanie niezbędnych kompetencji personelu zespołu inżynierskiego, opracowanie metod i kryteriów oceny kompetencji, ocenę i wykazanie umiejętności praktycznych.

19

An integrated approach for performance evaluation of mining industry: a case study of Iranian Steel Complex

Pezeshkan Mehdi, Hosseini Navid

Gospodarka Surowcami Mineralnymi

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2020

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T. 36, z. 3

5--28

EN

The continuous improvement in the industries and organizations hinges upon the evaluation of their performance. In fact, the performance evaluation assists organizations to identify their strengths and weaknesses and, accordingly, enhance their efficiency. As soon as the concept of sustainability was propounded in the engineering based industries, the performance evaluation got more importance due to the environmental issues and social concerns along with the economical aspects. Therefore, this paper is an attempt to propose an approach based on fuzzy best-worst method (BWM) and fuzzy inference system (FIS) in order to evaluate the performance of an Iranian steel complex in terms of sustainability concept. In the proposed approach, the weights of some selected criteria were determined by fuzzy BWM method and, then, the score of the under study industry was calculated in terms of economic, environmental, and social aspects. At the end, an FIS was developed to calculate the final score of the intended industry. In order to check the efficiency of the proposed approach, its performance was measured using expert knowledge as well as real data of a steel complex in Iran. A moderate to high performance has been achieved for the understudy case through conducting the proposed approach. It was suggested that the industry should focus on the criteria with both high weights and low evaluated scores (for example the environmental management technologies and knowledge criterion) to increase its performance evaluation score. The obtained results were indicative of the efficiency of the proposed approach.

PL

Ciągłe doskonalenie branż i organizacji zależy od oceny ich wydajności. W rzeczywistości ocena wyników pomaga organizacjom zidentyfikować ich mocne i słabe strony, a co za tym idzie, zwiększyć ich efektywność. Jak tylko koncepcja zrównoważonego rozwoju została zaproponowana w branżach opartych na inżynierii, ocena wydajności nabrała większego znaczenia ze względu na kwestie środowiskowe i społeczne, a także aspekty ekonomiczne. Artykuł jest próbą zaproponowania podejścia opartego na rozmytej metodzie best-worst (BWM) i rozmytym systemie wnioskowania (FIS) w celu oceny wydajności irańskiego kompleksu stalowego pod kątem koncepcji zrównoważonego rozwoju. W proponowanym podejściu, wagi wybranych kryteriów wyznaczono metodą rozmytą BWM, a następnie obliczono punktację badanej branży pod względem ekonomicznym, środowiskowym i społecznym. Na koniec opracowano rozmyty system wnioskowania FIS, aby obliczyć końcowy wynik dla planowanej branży. Aby sprawdzić efektywność proponowanego podejścia, mierzono jego wydajność, wykorzystując wiedzę ekspercką oraz rzeczywiste dane dotyczące kompleksu stalowego w Iranie. W analizowanym przypadku, poprzez zastosowanie proponowanego podejścia osiągnięto wyniki od umiarkowanych do wysokich. Zasugerowano, że w celu zwiększenia oceny wyników, branża powinna skupić się na kryteriach zarówno o dużej wadze, jak i nisko ocenianych punktach (na przykład technologie zarządzania środowiskowego i kryterium wiedzy). Uzyskane wyniki świadczyły o skuteczności zaproponowanego podejścia.

20

Phenomenological technique for prediction of cavitation erosion performance

Gireń B. G., Welzant A., Baran P.

Archives of Materials Science and Engineering

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2020

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Vol. 104, nr 2

69--85

EN

Purpose: Major aim of the work was to formulate 2-parameters models of the cavitation erosion process and to bring about the particular methods for prediction of its performance with due calculation formulas. Design/methodology/approach: Phenomenological model of the erosion supplemented with functional relationships between calculation parameters and the strength parameters stand for the foundations of the method. Having assumed the probabilistic nature of the process and fatigue regime of the material destruction, the volume loss in time has been determined as proportional to the integral of the appropriate probability function. Correlations between parameters have been derived by adjusting the computed erosion curves to the experimental ones for the vast diversity of the cases. Findings: Two different formulas for the volume loss of the material in time under cavitation loading have been derived. Research limitations/implications: Results obtained from both the International Cavitation Erosion Test program as well as the own experiments carried out at the rotating disk set-up supplied necessary experimental data. Preliminary verification of the method soundness was completed. Assumption on the independence of the calculation parameters on the loading conditions have been taken. The approach is valid provided the defined relationships are also independent on the type and amplitude of the loading. Practical implications: Achieving the objectives is expected to result in developing a technique for assessment of the material damage under cavitation loadings. Numerical implementation of the model completed with the derived functional relationships stand for a tool, enabling a prospective user to predict the material performance under defined cavitation loading. Originality/value: New formulas for calculating the efficiency of cavitation erosion, inferred from the models of high physical clarity are the original contribution to the methodology and techniques concerned.