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Number of results: 62
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Abstract

The successful application of a multi-clusteringbased neighborhood approach to recommender systems has led to increased recommendation accuracy and the elimination of divergence related to differences in clustering methods traditionally used. The Multi-Clustering Collaborative Filtering algorithm was developed to achieve this, as described in the author’s previous papers. However, utilizing multiple clusters poses challenges regarding memory consumption and scalability. Not all partitionings are equally advantageous, making selecting clusters for the recommender system’s input crucial without compromising recommendation accuracy. This article presents a solution for selecting clustering schemes based on internal indices evaluation. This method can be employed for preparing input data in collaborative filtering recommender systems. The study’s results confirm the positive impact of scheme selection on the overall recommendation performance, as it typically improves after the selection process. Furthermore, a smaller number of clustering schemes used as input for the recommender system enhances scalability and reduces memory consumption. The findings are compared with baseline recommenders’ outcomes to validate the effectiveness of the proposed approach.
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Authors and Affiliations

Urszula Kużelewska
1

  1. Faculty of Computer Science, Bialystok Uni-versity of Technology, Wiejska 45a, 15-351 Bialystok, Poland
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Abstract

The term extreme rainfall refers to an event during which the thresholds of various hydrological and geomorphic processes are exceeded. The frequency of extremes varies in different climatic zones and in time. The clustering of extreme events happens when the extremes are repeated every 2–3 years, every year or even several times a year. Such clusterings disturb the equilibrium of slope and river channel systems and are separated by periods of stability and recovery. The occurences of clusters are exemplified by present – day processes, historical records and geological records. On this base a model of phases with frequent and rare clusterings during the Holocene was constructed.
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Authors and Affiliations

Leszek Starkel
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Abstract

The article deals with the issue of formation and functioning of rural tourism clusters in Ukraine. Here, formation of cluster structures in rural tourism is at its initial stage. Analysis of existing clusters resulted in their classification into groups based on the criterion of specialization: lodging and food (farmsteads), agritourist and local history tourism clusters. Analysis of the main research models for the creation and analysis of rural tourism clusters functioning has been performed. A multilevel universal model of the rural tourism clusters with basic structural levels (basic, affiliate and accompanying) has been proposed for scientific and practical purposes. This model was used to form two cluster initiatives in the ethnographic region of the Ukrainian Carpathians – in the Boykivshchyna. The need to use foreign experience in rural tourism cluster research has been emphasized.

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Authors and Affiliations

Marta Malska
Lidiya Dubis
Yuriy Zinko
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Abstract

Clusters belong to the regional innovation system, which led to the formulation and implementation of the cluster-based policy in many countries. The positive impact of clusters on the competitiveness of regions was confirmed by empirical studies. Absence of clusters means retardation in a regional development. The implementation of cluster policy supporting coopetition into the scope of principled regional policy assumptions seems urgent. In this way effective conditions for the formation of growth poles around industries specific for a given region will be developed and, consequently, the economic specialization of individual regions will be achieved. Observation of the benefits resulting from the functioning of clusters in the region, taking into account their possible negative impact, will allow to determine the specificity of regional development policy based on clusters. These problems indicated above are the subject of this study, based on the Polish and foreign literature available on the subject employing the desk research method.

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Authors and Affiliations

Sylwia Guzdek
ORCID: ORCID
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Abstract

The Energy Law of April 10, 1997 initiated changes in the energy market in Poland. Actions taken on the basis of this law were aimed at the modernization and development of the power sector. Organizational and legal changes causing the development of distributed generation, thus increasing the level of market competition have been introduced. The care for high quality of customer service, including the protection of vulnerable customers, environmental protection, growing share of renewable energy and emission reduction requirements have become a reality. It seems, therefore, that it is necessary for the Polish energy sector to undergo permanent modernization, to develop the production and industrial infrastructure and to develop modern conventional technologies by way of implementing innovations in the field of energy companies. The author of the paper argues that it is indispensable to make a broadly understood transfer of knowledge and technology to the energy sector on the basis of a knowledge-based economy. This also applies to energy clusters, which currently constitute a platform for cooperation: entrepreneurs, scientific-research units, and public authorities. The functioning of these entities is an important catalyst for the transfer of knowledge and technologies. Their regional nature boosts competitiveness of the involved enterprises, and is a natural way of transferring knowledge to the energy market.
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Authors and Affiliations

Radosław Miśkiewicz
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Abstract

The paper discusses the use of multiclustering statistical analysis in the assessment of domestic wastewater filtration effectiveness. Calculations included data collected over four months of experiments with using waste as filling material of vertical flow filters for domestic sewage treatment. The effectiveness of pollutants removal was analysed in case of me-chanically shredded waste in the form of PET flakes, PUR foam trims, shredded rubber tires and wadding. The organic compounds (CODcr, BOD5) removal, suspend solids, biogens (as NH4+, PO43– ions) and oxygen saturation changing com-pared with sand filling was analysed. Multiclustering statistical analysis allowed to divide pollutants removal efficiency of analysed materials into 3 clusters, depending on the hydraulic loading. The first group consisted in quality parameters of treated sewage: the highest reduction of BOD5 and NH4-N. It included the values of quality parameters and indicators for the filtrates obtained at the lowest hydraulic load from columns filled with 60 cm of rubber tires or sand. The second group comprised the results for fillings containing foam, PET and rubber tires (the other hydraulic loads).It featured the highest reduction of total suspended solids and PO43–. Removal of easily biodegradable organic compounds was at a similar level in both cluster groups. The filter filled with polyester waste (wadding), which was as effective as 30 cm layer of sand, and the filters filled with 60 cm of sand working at the highest hydraulic load. Third group showed the lowest values of parameters and indicators for analysed filtrates.

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Authors and Affiliations

Dawid Bedla
Ewa Dacewicz
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Abstract

In the current industrial scenarios those involved in production and services distribution

are called to deal with a plurality of stakeholders, considering different interests, readings

and positions. This paper exploits the concept of collaboration in this fast changes and

flexible scenario by describing the characteristics of collaboration among enterprises and

their scope. In this context, the purpose of all managers to maximize utility, to save cost or

to minimize of transaction costs is hard to be reached. Under this prospective, to collaborate

with other firms is a logical way to work and to pursue the previous objectives. The purpose

of this paper is to define all the aspects of collaboration, mainly among enterprises, and the

reasons that can drive a manager to stipulate a collaboration agreement. Two different ways,

through collaboration can rise, have been described: collaboration induced by external body

(top-down collaboration) or born in a spontaneous way (bottom-up). The management of

the collaboration and the identification of key performance indicators, able to control the

development of the network system, is addressed by exploiting the Italian network contract

and the case study of the energy cluster.

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Authors and Affiliations

Teresa Taurino
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Abstract

Wireless sensor network is a dynamic field of networking and communication because of its increasing demand in critical Industrial and Robotics applications. Clustering is the technique mainly used in the WSN to deal with large load density for efficient energy conservation. Formation of number of duplicate clusters in the clustering algorithm decreases the throughput and network lifetime of WSN. To deal with this problem, advance distributive energy-efficient adaptive clustering protocol with sleep/wake scheduling algorithm (DEACP-S/W) for the selection of optimal cluster head is presented in this paper. The presented sleep/wake cluster head scheduling along with distributive adaptive clustering protocol helps in reducing the transmission delay by properly balancing of load among nodes. The performance of algorithm is evaluated on the basis of network lifetime, throughput, average residual energy, packet delivered to the base station (BS) and CH of nodes. The results are compared with standard LEACH and DEACP protocols and it is observed that the proposed protocol performs better than existing algorithms. Throughput is improved by 8.1% over LEACH and by 2.7% over DEACP. Average residual energy is increased by 6.4% over LEACH and by 4% over DEACP. Also, the network is operable for nearly 33% more rounds compared to these reference algorithms which ultimately results in increasing lifetime of the Wireless Sensor Network.
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Bibliography

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[2] K. Pavai, A. Sivagami and D. Sridharan, "Study of Routing Protocols in Wireless Sensor Networks,” 2009 International Conference on Advances in Computing, Control and Telecommunication Technologies, Trivandrum, Kerala, 2009, pp. 522-525.
[3] D. Goyal and M. R. Tripathy, "Routing Protocols in Wireless Sensor Networks: A Survey,"2012 Second International Conference on Advanced Computing & Communication Technologies, Rohtak, Haryana, 2012, pp. 474-480.
[4] NasirSaeed, Ahmed Bader, T.Y. Al-Naffouri, Mohamed-slim Alouini, “When Wireless Communication Faces COVID-19: Combating the Pandemic and Saving the Economy,” Research Gate Journal, May 2020.
[5] Jitendra Singh, Rakesh Kumar, “Clustering algorithms for wireless sensor networks: A review,” 2nd International Conference on Computing for Sustainable Global Development, May 2015.
[6] S. Misra and R. Kumar, "A literature survey on various clustering approaches in wireless sensor network," IEEE 2nd International Conference on Communication Control and Intelligent Systems (CCIS), Mathura, 2016, pp. 18-22.
[7] S. Mishra, R. Bano, S. Kumar and V. Dixit, "A literature survey on routing protocol in wireless sensor network," IEEE International Conference on Innovations in Information, Embedded and Communication Systems (ICIIECS), Coimbatore, 2017, pp. 1-4.
[8] Kalyani Wankhede, Sumedha Sirsikar, “Review of Clustering Algorithms in Wireless Sensor Networks,” International Journal of Advance Foundation and Research in Computer (IJAFRC), Volume 1, Issue 11, November 2014, pp.126-133.
[9] Sangho Yi, Junyoung Heo, Yookun Cho and Jiman Hong b, “PEACH: Power-efficient and adaptive clustering hierarch protocol for wireless sensor networks,” Computer Communications, ELSEVIER, 23 June 2007, pp. 2842–2852.
[10] K. T. Kim and H. Y. Youn, “Energy-Driven Adaptive Clustering Hierarchy (EDACH) for Wireless Sensor Networks,” International Federation of Info. Processing, vol. 3823, Dec. 2005, pp. 1098–1107.
[11] V. Loscri, G. Morabito and S. Marano, “A Two-Level Hierarchy for Low-Energy Adaptive Clustering Hierarchy(TL-LEACH),” IEEE Proceedings of Vehicular Technology Conference, vol. 3, 2005, pp. 1809-1813.
[12] S. Nasr, M. Quwaider, “LEACH Protocol Enhancement for Increasing WSN Lifetime,” 2020 11th International Conference on Information and Communication Systems (ICICS), April 2020, pp. 102-107.
[13] M. Kaddi, Z. Khalili, M. Bruchra, “A Differential Evolution Based Clustering and Routing Protocol for WSN,” 2020 International Conference on Mathematics and Information Technology, March 2020, pp. 190-195.
[14] G. Malshetty, B. Mathapati, “Efficient Clustering in WSN-Cloud using LBSO (Load Based Self Organised) technique,” Third International Conference on Trends in Electronics and Informatics(ICOEI), October 2019, pp. 1243-1247.
[15] K. Dubey, A. Yadav, P. Kumar, P. Shekar, P. Rajput, S. Kumar, “Power Optimization Algorithm for Heterogeneous WSN using Multiple Attributes,” Proceedings of Third International Conference on Computing Methodologies and Communication (ICCMC), August 2019, pp. 294-299.
[16] O. Younis, S. Fahmy, “HEED: A Hybrid Energy-Efficient Distributed Clustering Approach for Ad Hoc Sensor Networks,” IEEE Transactions on mobile computing, vol. 3(4) , 2004, pp. 1-36
[17] A. Manjeshwar, D. P. Agrawal, “TEEN: A Routing Protocol for Enhanced Efficiency in Wireless Sensor Networks,” 15th International Workshop on Parallel and Distributed Processing Symposium (IPDPS), 23–27 April 2001, pp. 2009–2015.
[18] A. Manjeshwar, D. P. Agrawal, “APTEEN: A Hybrid Protocol for Efficient Routing and Comprehensive Information Retrieval in Wireless Sensor Networks,” 2nd International Workshop on Parallel and Distributed Computing Issues in Wireless Networks and Mobile Computing,” April 2002, pp. 195–202.
[19] Chirihane Gherbi, Zibouda Aliouat, Mohamed Benmohammed, “A Novel Load Balancing Scheduling Algorithm For Wireless Sensor Networks,” Journal of Network And Systems Management (2019) 27, pp. 430–462.
[20] Heinzelman W,Chandrakasan A and Balakrishnan H, "Energy-Efficient Communication Protocols for Wireless Microsensor Networks," Proceedings of the 33rd Hawaaian International Conference on Systems Science (HICSS), January 2000.
[21] JiuqiangXu, Wei Liu, Fenggao Lang, Yuanyuan Zhang, Chenglong Wang, “Distance Measurement Model Based on RSSI in WSN,” Scientific Research Journal on Wireless Sensor Network, August 2010, pp. 606-611
[22] Nazir Babar, Hasbullah Halabi & Madani Sajjad, “Sleep/wake scheduling scheme for minimizing end-to-end delay in multi-hop wireless sensor networks,” EURASIP Journal on Wireless Communications and Networking, 2011, art. no 92. doi: 10.1186/1687-1499-2011-92.

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Authors and Affiliations

Shankar D. Chavan
1
Shahaji R. Jagdale
1
Dhanashree A. Kulkarni
1
Sneha R. Jadhav
1

  1. Dr. D. Y. Patil Institute of Technology, Pimpri, Pune
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Abstract

The development of electromobility is a challenge for the power system in both technical and economic-market terms. As of today, there are no analyses to determine the power necessary to supply the planned infrastructure and to estimate the incentives and economic benefits resulting from the modification of the settlement method. The document determining the legal regulations and the obligation to build vehicle charging stations for specific municipalities is the Act on Electromobility and Alternative Fuels. This act estimates that the development of electromobility, due to the specifics including not only individual vehicles, will take place in certain areas. The places which in the first stage will be dedicated to the potential implementation of the concept of electromobility will be municipalities covering large agglomerations. In addition, due to the local aspect, the development of electromobility may take place in the areas of energy clusters’ initiatives, which, using the policy of increasing energy awareness, are aimed at energy production from local renewable energy resources. The planned development of electromobility assumes a systematic increase in the number of electric cars caused by the introduction of support systems. The dynamization of this sector will cause an increase in the demand for electricity. Due to power system reasons, an important factor determining the level of energy consumption depending on the time of day may be an appropriate shape of the pricing for the charging service. Appropriate price list stimulation can affect the behavior of recipients, causing the charging of cars in the off-peak of electricity demand. The aim of the article is to characterize the scale of the phenomenon of electromobility in the context of the emergence of a charging points infrastructure along with the possibility of price-setting stimulation affecting the profile of energy demand. It is also important to consider the challenges and responsibilities of municipalities and energy clusters from the perspective of introducing electromobility.

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Authors and Affiliations

Kinga Bojda
Maciej Sołtysik
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Abstract

An analysis of the power system functioning and the behaviors of the energy market participants allows the trends taking place within years to be identified, including these associated with the evolution of the electric energy and power demand profiles. The problems of balancing the peak power demand are of both a short and long term nature, which implies the need for changes in the electricity generation sector. Apart from the existing “silo-type” generation units, the construction of distributed energy sources implemented in the civic formula in the framework of self-sufficient energy communes and energy clusters is becoming increasingly important. Support for these programs is realized both at the legislative level, as well as within dedicated competitions and ministerial activities. The financial support carried out by the National Fund for Environmental Protection and Water Management and the Regional Operational Programs is also noticeable. One of the activities aimed at spreading the idea of clustering was the competition for certified energy clusters, conducted by the Ministry of Energy. The goal of the contest was the promotion and development of the distributed energy sector, which could be used for the improvement of energy security in the local manner and constitute a basis for the knowledge necessary in planning and developing the state’s energy policy. The paper presents a synthetic analysis of the results of the competition for a certified energy cluster from the perspective of planning and operational needs related to the functioning of the power system. Further, the information about the investment plans of new generation capacities, including their breakdown with respect to type, achievable power and costs has been provided. Also, the balancing of the demand for electric energy by own generation within the energy clusters has been characterized for three time perspectives

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Authors and Affiliations

Maciej Sołtysik
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Abstract

In spite of technological, logistic and economic difficulties, interest in renewable energy sources in the world is consistently increasing. This trend is also observed in Poland, mainly due to the urgent need to tackle the problem of climate change, which is caused by the increasing concentration of gaseous pollutants in the atmosphere. The paper presents a short script of the issue of estimating renewable energy resources in Poland in the context of creating local low carbon economy plans at the level of municipalities/counties where RES sources should be taken into account. The author proposed an individual approach to estimate the potential of RES, taking the local conditions and the short characteristics of the small and medium companies sector in Poland into account. These companies have a great application potential to increase the share of renewable energies and to improve energy efficiency in their business. The actions, which are taken by the Ministry of Energy in the field of civil energy development, enhancing local energy security and the sustainable development of renewable energy resources support the development of energy clusters covering one district or five municipalities. In the article, the author presents data on the number of companies possessing a concession for generating electricity in RES installations in the power range from 40 kW to 200 kW. These companies can largely be the nucleus for creating a local cluster in which microgrids will be a key element.

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Authors and Affiliations

Tomasz Mirowski
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Abstract

Wireless sensor network (WSN) is assortment of sensor nodes proficient in environmental information sensing, refining it and transmitting it to base station in sovereign manner. The minute sensors communicate themselves to sense and monitor the environment. The main challenges are limited power, short communication range, low bandwidth and limited processing. The power source of these sensor nodes are the main hurdle in design of energy efficient network. The main objective of the proposed clustering and data transmission algorithm is to augment network performance by using swarm intelligence approach. This technique is based on K-mean based clustering, data rate optimization using firefly optimization algorithm and Ant colony optimization based data forwarding. The KFOA is divided in three parts: (1) Clustering of sensor nodes using K-mean technique and (2) data rate optimization for controlling congestion and (3) using shortest path for data transmission based on Ant colony optimization (ACO) technique. The performance is analyzed based on two scenarios as with rate optimization and without rate optimization. The first scenario consists of two operations as kmean clustering and ACO based routing. The second scenario consists of three operations as mentioned in KFOA. The performance is evaluated in terms of throughput, packet delivery ratio, energy dissipation and residual energy analysis. The simulation results show improvement in performance by using with rate optimization technique.
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Authors and Affiliations

Savita Sandeep Jadhav
1
Sangeeta Jadhav
2

  1. Dr. D.Y. Patil Institute of Technology, Pimpri, Pune, India
  2. Army Institute of Technology, Dighi Hills, Pune, India
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Abstract

This article presents a consistent solution of Transmit Power Control in centralized (clustered) wireless network with and without jamming. Depending on the policy assumed, appropriate solutions are applied to minimize the power used in a system or to satisfy expected Quality of Service. Because of specific nature of the system there is no optimal solution which can be applied in practice. Correctness and effectiveness of four proposed Transmit Power Control algorithms was presented in the form of computer simulation results in which the system capacity, mean power used and the number of successful links were described.

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Authors and Affiliations

Jarosław Michalak
ORCID: ORCID
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Abstract

This paper introduces a novel approach to building network cluster structures, based on the modified LEACH algorithm. The proposed solution takes into account the multitasking of the network infrastructure, resulting from various functions performed by individual nodes. Therefore, instead of a single head, dedicated to a given cluster, a set of heads is selected, the number of which corresponds to the number of performed functions. Outcomes of simulations, comparing the classical and the multifunctional approach, are presented. The obtained results confirm that both algorithms deliver similar levels of energy consumption, as well as efficiency in terms of the number of individual nodes discharged.
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Authors and Affiliations

A. Paszkiewicz
1
ORCID: ORCID
C. Ćwikła
2
M. Bolanowski
1
ORCID: ORCID
M. Ganzha
3
ORCID: ORCID
M. Paprzycki
3
ORCID: ORCID
M. Hodoň
4
ORCID: ORCID

  1. Department of Complex Systems, Rzeszow University of Technology, Al. Powstańców Warszawy 12, Rzeszów 35-959, Poland
  2. Rzeszow University of Technology, Al. Powstańców Warszawy 12, Rzeszów 35-959, Poland
  3. Systems Research Institute Polish Academy of Sciences, Newelska 6, Warszawa 01-447, Poland
  4. Department of Technical Cybernetics, University of Žilina, Univerzitná 8215/1, 010 26 Žilina, Slovakia
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Abstract

This paper details a hardware implementation of a distributed Θ(1) time algorithm allows to select dynamically the master device in ad-hoc or cluster-based networks in a constant time regardless the number of devices in the same cluster. The algorithm allows each device to automatically detect its own status; master or slave; based on identifier without adding extra overheads or exchanging packets that slow down the network. We propose a baseband design that implements algorithm functions and we detail the hardware implementation using Matlab/Simulink and Ettus B210 USRP. Tests held in laboratory prove that algorithm works as expected.

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Authors and Affiliations

Mohammed El Khattabi
Jelloul Elmesbahi
Ahmed Errami and Omar Bouattane Mohammed Khaldoun
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Abstract

In this paper cluster consensus is investigated for general fractional-order multi agent systems with nonlinear dynamics via adaptive sliding mode controller. First, cluster consensus for fractional-order nonlinear multi agent systems with general formis investigated. Then, cluster consensus for the fractional-order nonlinear multi agent systems with first-order and general form dynamics is investigated by using adaptive sliding mode controller. Sufficient conditions for achieving cluster consensus for general fractional-order nonlinear multi agent systems are proved based on algebraic graph theory, Lyapunov stability theorem andMittag-Leffler function. Finally, simulation examples are presented for first-order and general form multi agent systems, i.e. a single-link flexible joint manipulator which demonstrates the efficiency of the proposed adaptive controller.

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Authors and Affiliations

Zahra Yaghoubi
Heidar Ali Talebi
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Abstract

The interrelation between fuzzy logic and cluster renewal approaches for heat transfer modeling in a circulating fluidized bed (CFB) has been established based on a local furnace data. The furnace data have been measured in a 1296 t/h CFB boiler with low level of flue gas recirculation. In the present study, the bed temperature and suspension density were treated as experimental variables along the furnace height. The measured bed temperature and suspension density were varied in the range of 1131–1156 K and 1.93–6.32 kg/m3, respectively. Using the heat transfer coefficient for commercial CFB combustor, two empirical heat transfer correlation were developed in terms of important operating parameters including bed temperature and also suspension density. The fuzzy logic results were found to be in good agreement with the corresponding experimental heat transfer data obtained based on cluster renewal approach. The predicted bed-to-wall heat transfer coefficient covered a range of 109–241 W/(m2K) and 111–240 W/(m2), for fuzzy logic and cluster renewal approach respectively. The divergence in calculated heat flux recovery along the furnace height between fuzzy logic and cluster renewal approach did not exceeded ±2%.

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Authors and Affiliations

Artur Błaszczuk
Jarosław Krzywański
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Abstract

This paper focuses on assessment of the effect of flue gas recirculation (FGR) on heat transfer behavior in 1296t/h supercritical coal-fired circulating fluidized bed (CFB) combustor. The performance test in supercritical CFB combustor with capacity 966 MWthwas performed with the low level of flue gas recirculation rate 6.9% into furnace chamber, for 80% unit load at the bed pressure of 7.7 kPa and the ratio of secondary air to the primary air SA/PA = 0.33. Heat transfer behavior in a supercritical CFB furnace between the active heat transfer surfaces (membrane wall and superheater) and bed material has been analyzed for Geldart B particle with Sauter mean diameters of 0.219 and 0.246 mm. Bed material used in the heat transfer experiments had particle density of 2700 kg/m3. A mechanistic heat transfer model based on cluster renewal approach was used in this work. A heat transfer analysis of CFB combustion system with detailed consideration of bed-to-wall heat transfer coefficient distributions along furnace height is investigated. Heat transfer data for FGR test were compared with the data obtained for representative conditions without recycled flue gases back to the furnace through star-up burners.
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Authors and Affiliations

Artur Błaszczuk
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Abstract

Experimental research has been carried out in a supercritical circulating fluidized bed combustor in order to indicate the effect of the bed particle size on bed-to-wall heat transfer coefficient. The bed inventory used were 0.219, 0.246 and 0.411 mm Sauter mean particles diameter. The operating parameters of a circulating fluidized bed combustor covered a range from 3.13 to 5.11 m/s for superficial gas velocity, 23.7 to 26.2 kg/(m2s) for the circulation rate of solids, 0.33 for the secondary air fraction and 7500 to 8440 Pa pressure drop. Furthermore, the bed temperature, suspension density and the main parameters of cluster renewal approach were treated as experimental variables along the furnace height. The cluster renewal approach was used in order to predict the bed-to-wall heat transfer coefficient. A simple semi-empirical method was proposed to estimate the overall heat transfer coefficient inside the furnace as a function of particle size and suspension density. The computationally obtained results were compared with the experimental data of this work.
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Authors and Affiliations

A. Błaszczuk
W. Nowak
S. Jagodzik
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Abstract

The aim of this article is to evaluate the quality of the Danube River in its course through Serbia as well as to demonstrate the possibilities for using three statistical methods: Principal Component Analysis (PCA), Factor Analysis (FA) and Cluster Analysis (CA) in the surface water quality management. Given that the Danube is an important trans-boundary river, thorough water quality monitoring by sampling at different distances during shorter and longer periods of time is not only ecological, but also a political issue. Monitoring was carried out at monthly intervals from January to December 2011, at 17 sampling sites. The obtained data set was treated by multivariate techniques in order, firstly, to identify the similarities and differences between sampling periods and locations, secondly, to recognize variables that affect the temporal and spatial water quality changes and thirdly, to present the anthropogenic impact on water quality parameters.

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Authors and Affiliations

Danijela Voza
Milovan Vukovic
Ljiljana Takic
Djordje Nikolic
Ivana Mladenovic-Ranisavljevic
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Abstract

In the study suitability of water quality index approach and environmetric methods in fi ngerprinting heavy metal pollution as well as comparison of spatial variability of multiple contaminants in surface water were assessed in the case of The Gediz River Basin, Turkey. Water quality variables were categorized into two classes using factor and cluster analysis. Furthermore, soil contamination index was adapted to water pollution index and used to fi nd out the relative relationship between the reference standards and the current situation of heavy metal contamination in water. Results revealed that surface water heavy metal content was mainly governed by metal processing, textile and tannery industries in the region. On the other hand, metal processing industry discharges mainly degraded quality of water in Kemalpasa and Menemen. Furthermore, Kemalpasa region has been heavily affected from tannery and textile industries effl uents. Moreover, pollution parameters have not been infl uenced by changes in physical factors (discharge and temperature). This study indicated the effectiveness of water quality index approach and statistical tools in fi ngerprinting of pollution and comparative assessment of water quality. Both methods can assist decision makers to determine priorities in management practices.
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Authors and Affiliations

Hülya Boyacioglu
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Abstract

The purpose of this work is to find a correlation for heat transfer to walls in a 1296 t/h supercritical circulating fluidised bed (CFB) boiler. The effect of bed-to-wall heat transfer coefficient in a long active heat transfer surface was discussed, excluding the radiation component. Experiments for four different unit loads (i.e. 100% MCR, 80% MCR, 60% MCR and 40% MCR) were conducted at a constant excess air ratio and high level of bed pressure (ca. 6 kPa) in each test run. The empirical correlation of the heat transfer coefficient in a large-scale CFB boiler was mainly determined by two key operating parameters, suspension density and bed temperature. Furthermore, data processing was used in order to develop empirical correlation ranges between 3.05 to 5.35 m·s-1 for gas superficial velocity, 0.25 to 0.51 for the ratio of the secondary to the primary air, 1028 to 1137K for bed temperature inside the furnace chamber of a commercial CFB boiler, and 1.20 to 553 kg·m-3 for suspension density. The suspension density was specified on the base of pressure measurements inside the boiler’s combustion chamber using pressure sensors. Pressure measurements were collected at the measuring ports situated on the front wall of the combustion chamber. The obtained correlation of the heat transfer coefficient is in agreement with the data obtained from typical industrial CFB boilers.

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Authors and Affiliations

Wojciech Nowak
Artur Błaszczuk
Szymon Jagodzik

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