Wyniki wyszukiwania - BazTech

1

Comparative analysis of different trust metrics of user-user trust-based recommendation system

Roy Falguni, Hasan Mahamudul

Computer Science

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2022

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T. 23 (3)

335--373

EN

Information overload is the biggest challenge nowadays for any website – especially e-commerce websites. However, this challenge has arisen due to the fast growth of information on the web (WWW) along with easier access to the internet. A collaborative filtering-based recommender system is the most useful application for solving the information overload problem by filtering relevant information for users according to their interests. However, the current system faces some significant limitations such as data sparsity, low accuracy, cold-start, and malicious attacks. To alleviate the above-mentioned issues, the relationship of trust incorporates in the system where it can be among users or items; such a system is known as a trust-based recommender system (TBRS). From the user perspective, the motive of a TBRS is to utilize the reliability among users to generate more-accurate and trusted recommendations. However, the study aims to present a comparative analysis of different trust metrics in the context of the type of trust definition of TBRS. Also, the study accomplishes 24 trust metrics in terms of the methodology, trust properties & measurements, validation approaches, and the experimented data set.

2

Analysis of Coverage and Area Spectral Efficiency under Various Design Parameters of Heterogeneous Cellular Network

Abbasi Anum, Shaikh M. Mujtaba, Dahri Safia, Soomro Sarfraz Ahmed, Panhwar Fozia Aijaz

International Journal of Electronics and Telecommunications

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2021

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Vol. 67, No. 4

639--645

EN

As day by day the population is increasing, the use of mobile phones and different applications is increasing which requires high data rate for transmission. Homogeneous cellular network cannot fulfill the demand of mobile users, so creating a heterogeneous cellular network (HCN) is a better choice for higher coverage and capacity to fulfil the increasing demand of upcoming 5G and ultra-dense cellular networks. In this research, the impact of antenna heights and gains under varying pico to macro base stations density ratio from 2G to 5G and beyond on two-tier heterogeneous cellular network has been analyzed for obtaining optimum results of coverage and area spectral efficiency. Furthermore, how the association of UEs affects the coverage and ASE while changing the BSs antenna heights and gains has been explored for the two-tier HCN network model. The simulation results show that by considering the maximum macro BS antenna height, pico BS antenna height equal to user equipment (UE) antenna height and unity gains for both macro and pico tiers, the optimum coverage and area spectral efficiency (ASE) for a two-tier fully loaded heterogeneous cellular network can be obtained.

3

Badanie pokrycia radiowego w bezprzewodowej sieci kampusowej

Pluta Sławomir, Grytz Mateusz

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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2019

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nr 9

752--755

PL

Przedstawiono wyniki prac badawczych prowadzonych w celu oceny prawidłowości planowania kampusowej sieci WLAN Politechniki Opolskiej, realizującej usługę Eduroam. Wykonano pomiary stopnia pokrycia budynku sygnałem radiowym, generowanym przez rzeczywistą sieć WLAN w warunkach terenowych II Kampusu PO.

EN

The article presents the results of research conducted in order to asses quality of campus wireless area network planning for Eduroam service. Measurements of the degree of coverage of the building with a radio signal generated by the actual WLAN network in the field conditions of the 2nd Campus of The Opole University of Technology were carried out.. Examinations of the coverage were carried out in an indoor environment and outdoor environment. The WLAN network is well designed, and the place of installation of access points allows favorable propagation of radio waves, also in classrooms separated by a wall, with an acceptable reduction of the radio signal level.

4

Klasyfikacja danych z wykorzystaniem zmodyfikowanego podejścia opartego na dynamicznym programowaniu

Zielosko B., Żabiński K.

Studia Informatica

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2017

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Vol. 38, nr 2

45--54

PL

Artykuł stanowi kontynuację badań dotyczących zmodyfikowanego algorytmu dynamicznego programowania dla optymalizacji reguł decyzyjnych względem pokrycia. Praca przedstawia wyniki eksperymentalne dotyczące regułowego klasyfikatora, dla zbiorów danych umieszczonych w Repozytorium Uczenia Maszynowego.

EN

The article is a continuation of research connected with a modified dy-namic programming algorithm for optimization of decision rules relative to coverage. The paper contains experimental results for rule based classifier using data sets from UCI Machine Learning Repository.

5

An estimation method of message receiving probability for a satellite automatic identification system using a binomial distribution model

Seta T., Matsukura H., Aratani T., Tamura K.

Zeszyty Naukowe Akademii Morskiej w Szczecinie

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2016

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nr 46 (118)

101--107

EN

Automatic identification system (AIS) data are used to analyze vessels’ positions or maritime traffic. Recently, satellites are being adopted for gathering AIS data (satellite AIS). A satellite AIS can gather AIS data from all over the world, including the center of the ocean. However, because a satellite moves around the world every day, there is a very short window of time that the satellite can receive signals from some specific area. Furthermore, because a satellite AIS receives signals simultaneously from a wider area than a terrestrial AIS does, the satellite AIS has lower rate of signal reception, especially near vessel congested areas. This may cause many unrecognized vessels. For this situation, this paper proposes a new method to estimate the number of unrecognized vessels based on a binomial distribution model. With this method, we are able to estimate the number of unrecognized vessels just from satellite AIS data themselves.

6

Application of Dynamic Programming Approach to Optimization of Association Rules Relative to Coverage and Length

Zielosko B.

Fundamenta Informaticae

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2016

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Vol. 148, nr 1/2

87--105

EN

In the paper, an application of dynamic programming approach to global optimization of approximate association rules relative to coverage and length is presented. It is an extension of the dynamic programming approach to optimization of decision rules to inconsistent tables. Experimental results with data sets from UCI Machine Learning Repository are included.

7

Ocena stanu roślinności na zielonych ścianach z wykorzystaniem metod teledetekcyjnych

Skarżyński D., Pływaczyk A., Pęczkowski G.

Inżynieria Ekologiczna

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2015

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Nr 43

166--171

PL

Badania nad możliwością wykorzystania metod teledetekcyjnych w celu oceny stanu roślinności na zielonych ścianach wykonano na modelach doświadczalnych w latach 2010–2011. Analizowano dwa modele różniące się pomiędzy sobą podłożem wegetacyjnym: model retencyjny (MR I) z substratem glebowym oraz model ekonomiczny (ME II) z filcem hydroponicznym. W poszczególnych panelach posadzono rośliny reprezentujące krzewy, byliny oraz trawy. Łącznie na modelach doświadczalnych zastosowano 60 gatunków roślin dobranych w zależności od wystawy ścian. Ocenę kondycji roślin wykonano na podstawie prowadzonych obserwacji terenowych oraz analizy znormalizowanego wskaźnika roślinności NDVI (ang. Normalized Difference Vegetation Index). Stwierdzono, że roślinność na modelu retencyjnym (MR I) posiada znacznie wyższe wartości wskaźnika NDVI w porównaniu z modelem ekonomicznym (ME II). Porównanie procentowego pokrycia paneli modelu retencyjnego (MR I) i ekonomicznego (ME II) przez roślinny wykonano poprzez oddzielenie płaszczyzny tła od powierzchni roślin, ustalając jako kryterium podziału wskaźnik NDVI z przedziału od -1 do 0,2. Wykazano wyraźny kontrast pomiędzy stopniem pokrycia na badanych modelach na poszczególnych elewacjach. Na modelu retencyjnym (MR I) pokrycie paneli roślinami było znacznie większe niż na modelu ekonomicznym (ME II), gdzie rozwój roślin był ograniczony. Rozwój roślinności na modelu retencyjnym (MR I) z wykorzystaniem substratu glebowego w panelach roślinnych był prawidłowy co wskazuje na możliwość stosowania tego typu rozwiązań w warunkach klimatycznych Dolnego Śląska. Roślinność na modelu ekonomicznym (ME II) charakteryzuje gorszy rozwój w całym okresie wegetacyjnym, dlatego też nie jest on zalecany. Badania wykazały, że możliwa jest ocena stanu roślinności na zielonych ścianach z wykorzystaniem metod teledetekcyjnych bazujących na zmodyfikowanym sprzęcie fotograficznym.

EN

Research on the possibility of using remote sensing methods to evaluate condition of vegetation on the green walls were performed on experimental models in 2010–2011. Two models that differ from one another with vegetation layer were analyzed: a retention model (MR I) with substrate soil and an economic model (ME II) with hydroponic felt. In the individual panels plants representing shrubs, perennials and grasses were planted. In total, on experimental models 60 plant species was applied depending on the exhibition of the walls. The evaluation of the plants condition was performed based on field observations and the analysis of Normalized Difference Vegetation Index (NDVI). Evaluation of vegetation condition using remote sensing methods leads to the conclusion that the vegetation on retention model (MR I) have a much higher NDVI index value compared with the economic model (ME II). The comparison of the percent coverage of panels on retention model (MR I) and economic model (ME II) by the plants was done by separating the background plane from the plant surface. As a division criterion NDVI ratio in the range from -1 to 0.2 was taken. The results showed a clear contrast between the level of plant coverage of the examined models for individual facades. On the retention model (MR I) panels plant covering was significantly higher than on an economic model (ME II) where plant growth was limited. The growth of vegetation on the retention model (MR I) using substrate soil in plant panels was normal suggesting the potential use of such solutions in the climatic conditions of Lower Silesia. Vegetation on the economic model (ME II) is characterized by a worse growth throughout the growing season, which is why it is not recommended. The study showed that it is possible to evaluate the conditions of vegetation on the green walls with the use of remote sensing methods based on a modified photographic camera.

8

Relationships Between Length and Coverage of Decision Rules

Amin T., Chikalov I., Moshkov M., Zielosko B.

Fundamenta Informaticae

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2014

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Vol. 129, nr 1/2

1--13

EN

The paper describes a new tool for study relationships between length and coverage of exact decision rules. This tool is based on dynamic programming approach. We also present results of experiments with decision tables from UCI Machine Learning Repository.

9

Coverage of exact decision rules

Zielosko B.

Studia Informatica

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2013

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Vol. 34, nr 2A

251--262

PL

W artykule zaproponowano heurystykę na podstawie algorytmu dynamicznego programowania dla optymalizacji dokładnych reguł decyzyjnych odnośnie do pokrycia. Celem przeprowadzonych badań jest: (i) zbadanie pokrycia reguł konstruowanych za pomocą proponowanego algorytmu oraz porównanie z pokryciem reguł konstruowanych za pomocą algorytmu dynamicznego programowania, (ii) zbadanie rozmiaru grafu (liczba węzłów i krawędzi w skierowanym grafie acyklicznym) skonstruowanego za pomocą proponowanego algorytmu oraz porównanie go z rozmiarem grafu skonstruowanego za pomocą algorytmu dynamicznego programowania.

EN

In the paper, author proposes a heuristics based on dynamic programming algorithm for optimization of exact decision rules relative to coverage. There are two aims for the proposed algorithm: (i) study of coverage of rules and comparison with coverage of rules constructed by the dynamic programming algorithm, (ii) study of size of directed acyclic graph (the number of nodes and edges) and comparison with size of the graph constructed by the dynamic programming algorithm.

10

An algorithm for joint location, coverage and routing in wireless sensor networks

Jagusiak S., Józefczyk J.

Journal of Theoretical and Applied Computer Science

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2013

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Vol. 7, nr 3

61--71

EN

This paper deals with selected joint problem of location, coverage and routing in a class of wireless sensor networks. The minimization of the total cost of data collection and transmission as well as sensors and sinks location is considered. Its NP-hardness is justified and a heuristic solution algorithm based on the result of the circulation problem in a directed graph is proposed. The quality of the algorithm has been assessed during numerical experiments, and the examples of corresponding results are presented.

11

Dynamic Programming Approach for Partial Decision Rule Optimization

Amin T., Chikalov I., Moshkov M., Zielosko B.

Fundamenta Informaticae

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2012

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Vol. 119, nr 3/4

233-248

EN

This paper is devoted to the study of an extension of dynamic programming approach which allows optimization of partial decision rules relative to the length or coverage. We introduce an uncertainty measure J(T) which is the difference between number of rows in a decision table T and number of rows with the most common decision for T. For a nonnegative real number , we consider γ-decision rules (partial decision rules) that localize rows in subtables of T with uncertainty at most γ. Presented algorithm constructs a directed acyclic graph Δ(T) which nodes are subtables of the decision table T given by systems of equations of the kind "attribute = value". This algorithm finishes the partitioning of a subtable when its uncertainty is at most . The graph Δ(T) allows us to describe the whole set of so-called irredundant γ-decision rules. We can optimize such set of rules according to length or coverage. This paper contains also results of experiments with decision tables from UCI Machine Learning Repository.

12

Considerations on coverage and navigation in wireless mobile sensor networks

Goszczynski T., Pilat Z.

Journal of Automation Mobile Robotics and Intelligent Systems

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2011

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Vol. 5, No. 1

58-63

EN

In wireless mobile sensor networks, periodic calculation of coverage is very important, since mobile sensors can be moved adequately to current needs, thus increasing the coverage. Those moves require the execution of navigation tasks. Global network central algorithms for those tasks are very costly regarding energy consumption and computational resources. Considerations presented herein pertain to the best algorithms for a network of numerous small mobile sensor nodes used for monitoring of large terrains. Localized algorithms suggested in this paper help calculate the coverage on-line and locally with the involvement of neighboring nodes only. Furthermore, localized collaborative navigation is presented. It enables yielding position estimation with no GPS use and ensures improvement rather than deterioration over time. It uses multi-sensor fusion algorithms based on optimization and a distributed iterative extended Kalman Filter.

13

A Survey of Multi-Objective Deployment in Wireless Sensor Networks

Marks M.

Journal of Telecommunications and Information Technology

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2010

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nr 3

36-41

EN

The major challenge in designing wireless sensor networks (WSNs) is to find tradeoff between the desired and contrary requirements for the lifetime, coverage or cost while coping with the computation, energy and communication constraints. This paper examines the optimal placement of nodes for a WSN. It is impossible to consider the deployment of the nodes separately from WSNs applications. We highlight the properties of WSNs applications that determine the placement problem. We identify and enumerate the various objectives that should be considered. The paper provides an overview and concentrates on multi-objective strategies, their assumptions, optimization problem formulation and results.

14

A hybrid-mesh solution for coverage issues in WiMAX metropolitan area networks

Gierłowski K., Wodniak J., Nowicki K.

Journal of Telecommunications and Information Technology

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2008

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nr 1

20-28

EN

The new WiMAX technology offers several advantages over the currently available (GSMor UMTS-based) solutions. It is a cost effective, evolving, and robust technology providing quality of service guarantees, high reliability, wide cov- erage and non-line-of-sight (NLOS) transmission capabilities. All these features make it particularly suitable for densely populated urban environments. In this paper we discuss the design and implementation difficulties concerning network coverage discovered in a test-bed implementation of WiMAX. We point out the presence of unexpected "white spots" in the coverage, which are not inherently characteristic of the WiMAX concept. As a possible remedy to this significant drawback of the otherwise very promising technology, we consider reconfigurable mesh organization of WiMAX base stations. We also suggest directions for further development of this kind of network operation, partly based on our practical experience. Despite the clear advantages of the mesh mode in WiMAX networks, its development is currently at an early stage, due to the high complexity of the necessary mechanisms. In this situation, we propose an original, much simpler solution: the so-called support-mesh mode.

15

Analiza przestrzenna z użyciem obiektów ciągłych i jej zastosowanie w leśnictwie

Łabaj A.

Roczniki Geomatyki

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2004

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T. 2, z. 4

51-58

EN

Analysis of continuous fields (coverages), widely known in GIS technology, has not yet been used to significant degree in the Spatial Information System created for the needs of the State Forests. Also, there are not many scientific and conceptual works in the area of continuous fields modeling for the needs of forestry. In the paper, the following subjects are presented: 1) two potential areas for application of continuous models in forest districts, i.e. digital terrain model (DTM) and soil maps when discussing the method of their creation and use, 2) growing possibilities of using continuous fields models, particularly DTM, in GIS technology to make multi-variant analyses for the needs of the State Forests Administration, 3) prospects for development of large scale DTM in Poland, including for the needs of forestry. Conditions necessary for successful application of continuous fields models in forest districts were defined as follows: 1) accumulation of precise source data, 2) providing applications for appropriate analyses and 3D visualisation, 3) staff training.

16

Extraction of Structure of Medical Diagnosis from Clinical Data

Tsumoto S.

Fundamenta Informaticae

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2004

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Vol. 59, nr 2,3

271--285

EN

One of the most important problems with rule induction methods is that they cannot extract rules, which plausibly represent expert decision processes. In this paper, the characteristics of experts' rules are closely examined and a new approach to extract plausible rules is introduced, which consists of the following three procedures. First, the characterization of decision attributes (given classes) is extracted from databases and the concept hierarchy for given classes is calculated. Second, based on the hierarchy, rules for each hierarchical level are induced from data. Then, for each given class, rules for all the hierarchical levels are integrated into one rule. The proposed method was evaluated on a medical database, the experimental results of which show that induced rules correctly represent experts' decision processes.