Browsing by Subject "Information systems"

Now showing 1 - 20 of 22

Open Access
An analysis of manipulated information and respective alternative costs in information systems and in decision making structures
(International Institute of Informatics and Systemics, IIIS, 2006) Güvenen O.; Öztürk, M.H.
Today Information Technologies create base for the most important decision support systems for the practices in academia, business and politics. The effectiveness and success of operations that are supported by information systems are directly correlated with the quantity, accuracy, timing, credibility and the quality of the information that prevails in the system. Rapid development of these technologies in recent decades allows high level of information transaction and communication through the whole world. The quantity of information that flows through information systems has increased tremendously. New researches and technological applications in this area aim to improve the systems quantitatively. However, despite a huge and continuous increase in information flow, the quality and reliability of the information in the systems are doubtful from many perspectives. We believe that quality and reliability considerations in information technologies are not handled by researchers and users adequately. So in this research we decided to discuss about quality and reliability aspects of the information flow. To be able to evaluate the information from qualitative perspectives, we believe that it is crucial to handle the problem in science and especially in social sciences by endogenising socio-economic phenomena and science methodology approaches. We hope this work will create a stimulus for researchers of Information Technologies and Systems to give importance to the reliability and quality of information issues.
Open Access
Auction based scheduling for distributed systems
(International Institute of Informatics and Systemics, 2006) Zarifoğlu, Emrah; Sabuncuoğlu, İhsan
Businesses deal with huge databases over a geographically distributed supply network. When this is combined with scheduling and planning needs, it becomes too difficult to handle. Recently, Fast Consumer Goods sector tends to consolidate their manufacturing facilities on a single supplier serving to a distributed customer network. This decentralized structure causes imperfect information sharing between customers and the supplier. We model this problem as a single machine distributed scheduling problem with job agents representing the customers and the machine agent representing the supplier. We developed Auction Based Algorithm by exploiting the opportunity to use game theoretic approach to solve the problem in the decentralized utility case. Results of our extensive computational experiments indicate that Auction Based Algorithm converges to the upper bound found for the total utility measure.
Open Access
Automatic detection of salient objects and spatial relations in videos for a video database system
(Elsevier BV, 2008-10) Sevilmiş, T.; Baştan M.; Güdükbay, Uğur; Ulusoy, Özgür
Multimedia databases have gained popularity due to rapidly growing quantities of multimedia data and the need to perform efficient indexing, retrieval and analysis of this data. One downside of multimedia databases is the necessity to process the data for feature extraction and labeling prior to storage and querying. Huge amount of data makes it impossible to complete this task manually. We propose a tool for the automatic detection and tracking of salient objects, and derivation of spatio-temporal relations between them in video. Our system aims to reduce the work for manual selection and labeling of objects significantly by detecting and tracking the salient objects, and hence, requiring to enter the label for each object only once within each shot instead of specifying the labels for each object in every frame they appear. This is also required as a first step in a fully-automatic video database management system in which the labeling should also be done automatically. The proposed framework covers a scalable architecture for video processing and stages of shot boundary detection, salient object detection and tracking, and knowledge-base construction for effective spatio-temporal object querying. © 2008 Elsevier B.V. All rights reserved.
Open Access
A bilevel uncapacitated location/pricing problem with Hotelling access costs in one-dimensional space
(International Conference on Information Systems, Logistics and Supply Chain, 2016) Arbib, C.; Pınar, Mustafa Ç.; Tonelli, M.
We formulate a spatial pricing problem as bilevel non-capacitated location: a leader first decides which facilities to open and sets service prices taking competing offers into account; then, customers make individual decisions minimizing individual costs that include access charges in the spirit of Hotelling. Both leader and customers are assumed to be risk-neutral. For non-metric costs (i.e., when access costs do not satisfy the triangle inequality), the problem is NP-hard even if facilities can be opened at no fixed cost. We describe an algorithm for solving the Euclidean 1-dimensional case (i.e., with access cost defined by the Euclidean norm on a line) with fixed opening costs and a single competing facility.
Open Access
BilVideo: Design and implementation of a video database management system
(Springer, 2005) Dönderler, M. E.; Şaykol, E.; Arslan, U.; Ulusoy, Özgür; Güdükbay, Uğur
With the advances in information technology, the amount of multimedia data captured, produced, and stored is increasing rapidly. As a consequence, multimedia content is widely used for many applications in today's world, and hence, a need for organizing this data, and accessing it from repositories with vast amount of information has been a driving stimulus both commercially and academically. In compliance with this inevitable trend, first image and especially later video database management systems have attracted a great deal of attention, since traditional database systems are designed to deal with alphanumeric information only, thereby not being suitable for multimedia data. In this paper, a prototype video database management system, which we call BilVideo, is introduced. The system architecture of BilVideo is original in that it provides full support for spatio-temporal queries that contain any combination of spatial, temporal, object-appearance, external-predicate, trajectory-projection, and similarity-based object-trajectory conditions by a rule-based system built on a knowledge-base, while utilizing an object-relational database to respond to semantic (keyword, event/activity, and category-based), color, shape, and texture queries. The parts of BilVideo (Fact-Extractor, Video-Annotator, its Web-based visual query interface, and its SQL-like textual query language) are presented, as well. Moreover, our query processing strategy is also briefly explained. © 2005 Springer Science + Business Media, Inc.
Open Access
CiSE: a circular spring embedder layout algorithm
(Institute of Electrical and Electronics Engineers, 2013) Dogrusoz, U.; Belviranli, M. E.; Dilek, A.
We present a new algorithm for automatic layout of clustered graphs using a circular style. The algorithm tries to determine optimal location and orientation of individual clusters intrinsically within a modified spring embedder. Heuristics such as reversal of the order of nodes in a cluster and swap of neighboring node pairs in the same cluster are employed intermittently to further relax the spring embedder system, resulting in reduced inter-cluster edge crossings. Unlike other algorithms generating circular drawings, our algorithm does not require the quotient graph to be acyclic, nor does it sacrifice the edge crossing number of individual clusters to improve respective positioning of the clusters. Moreover, it reduces the total area required by a cluster by using the space inside the associated circle. Experimental results show that the execution time and quality of the produced drawings with respect to commonly accepted layout criteria are quite satisfactory, surpassing previous algorithms. The algorithm has also been successfully implemented and made publicly available as part of a compound and clustered graph editing and layout tool named Chisio. © 1995-2012 IEEE.
Open Access
Diffusion of geograpgic information system at municipalities in Istanbul
(Chamber of Mining Engineers of Turkey, 2015-04) Çavur, M.; Özturan, M.; Karaduman, C.; İçli, Abdullah Bera
This study aims to develop a better understanding of diffusion of Geographic Information Systems within municipalities and examines the infrastructure of Istanbul municipalities and whether they are ready for this technology or not. This study uses two research methods: The first one comprises interviews with the experts of GIS in Turkey. The second one comprises questionnaires conducted with Geographic Information Systems - related departments of Istanbul municipalities. Data collected online have been analyzed by using descriptive statistics, reliability tests, Anova and regression to test the hypotheses. One of the findings is that almost half of the municipalities implement Geographic Information Systems without a vision or a plan for the future. Another finding is that Geographic Information Systems is mainly used to perform registration and maintenance functions instead of supporting the decision-making process. Finally, there is an optimistic expectation of municipalities regarding the use of Geographic Information Systems in the future.
Open Access
E-museum: web-based tour and information system for museums
(IEEE, 2006) Baştanlar, Y.; Altıngövde, İsmail Şenol; Aksay, A.; Alav, O.; Çavuş, Özge; Yardımcı, Y.; Ulusoy, Ozgur; Güdükbay, Uğur; Çetin, A. Enis; Akar, G. B.; Aksoy, Selim
A web-based system - consisting of data entrance, access and retrieval modules - is constructed for museums. Internet users that visit the e-museum, are able to view the written and visual information belonging to the artworks in the museum, are able to follow the virtual tour prepared for the different sections of the museum, are able to browse the artworks according to certain properties, are able to search the artworks having the similar visual content with the viewed artwork. © 2006 IEEE.
Open Access
Effectiveness of information systems outsourcing: An exploratory case study
(IADIS, 2012) Uçar, Erkan; Bilgen, S.
The objective of this research is to construct an assessment model for measuring the effectiveness of Information Systems (IS) outsourcing. "Lack of expertise" and "cost effectiveness" constitute the major points of motivation for IS outsourcing. Although various decision models and analytical frameworks have been modeled before, the literature is not abundant on a complete qualitative model. In contrast with the decision models which are executed before an outsourcing engagement (a-priori), an effectiveness assessment model will be an a-posteriori guide which will enable the clients to measure their outsourcing performance and re-evaluate their business and management strategies. This paper examines the factors for outsourcing effectiveness through the framework of an exploratory case study for an IS developed by a major Turkish software house for a public organization. © 2012 IADIS.
Open Access
Empirical distributions of daily equity index returns : a comparison
(Elsevier Ltd, 2016) Corlu, C. G.; Meterelliyoz, M.; Tiniç, M.
The normality assumption concerning the distribution of equity returns has long been challenged both empirically and theoretically. Alternative distributions have been proposed to better capture the characteristics of equity return data. This paper investigates the ability of five alternative distributions to represent the behavior of daily equity index returns over the period 1979-2014: the skewed Student-t distribution, the generalized lambda distribution, the Johnson system of distributions, the normal inverse Gaussian distribution, and the g-and-h distribution. We find that the generalized lambda distribution is a prominent alternative for modeling the behavior of daily equity index returns. © 2016 Elsevier Ltd. All rights reserved.
Open Access
Evaluating higher education performance via machine learning during disruptive times: a case of applied education in Türkiye
(Wiley, 2024-12) Yılmaz, Semih Sait; Collins, Ayşe; Ali, Seyid Amjad
In response to the COVID-19 pandemic, an abrupt wave of digitisation and online migration swept the higher education institutions around the globe. In the aftermath of this digital transformation which endures as the legacy of the pandemic, what lacks in knowledge is how effective the anti-COVID measures were in maintaining quality education. Using machine learning to analyse student grades as a proxy for educational standards, this study investigates and demonstrates the evaluative potential of machine learning (vs. traditional statistics) with respect to not only crisis responses in education but also applied studies such as Information Systems and Tourism. Main implication of this study is the analytical utility of machine learning even when educational data are irregular and small. However, incorporating accurate and meaningful data points into the existing online educational systems is crucial to leverage this utility of machine learning.
Open Access
Evaluation of a broadcast scheduling algorithm
(Springer, Berlin, Heidelberg, 2001) Karakaya, M.; Ulusoy, Özgür
One of the two main approaches of data broadcasting is pull- based data delivery. In this paper, we focus on the problem of scheduling data items to broadcast in such a pull-based environment. Previous work has shown that the Longest Wait First heuristic has the best performance results compared to all other broadcast scheduling algorithms, however the decision overhead avoids its practical implementation. Observing this fact, we propose an efficient broadcast scheduling algorithm which is based on an approximate version of the Longest Wait First heuristic. We also compare the performance of the proposed algorithm against well- known broadcast scheduling algorithms. © Springer-Verlag Berlin Heidelberg 2001.
Open Access
A framework for applying the principles of depth perception to information visualization
(Association for Computing Machinery, 2013) Zeynep, C. Y.; Bulbul, A.; Capin, T.
During the visualization of 3D content, using the depth cues selectively to support the design goals and enabling a user to perceive the spatial relationships between the objects are important concerns. In this novel solution, we automate this process by proposing a framework that determines important depth cues for the input scene and the rendering methods to provide these cues. While determining the importance of the cues, we consider the user's tasks and the scene's spatial layout. The importance of each depth cue is calculated using a fuzzy logic-based decision system. Then, suitable rendering methods that provide the important cues are selected by performing a cost-profit analysis on the rendering costs of the methods and their contribution to depth perception. Possible cue conflicts are considered and handled in the system. We also provide formal experimental studies designed for several visualization tasks. A statistical analysis of the experiments verifies the success of our framework. © 2013 ACM.
Open Access
Keyphrase extraction through query performance prediction
(Sage Publications Ltd., 2012) Ercan, G.; Cicekli, I.
Previous research shows that keyphrases are useful tools in document retrieval and navigation. While these point to a relation between keyphrases and document retrieval performance, no other work uses this relationship to identify keyphrases of a given document. This work aims to establish a link between the problems of query performance prediction (QPP) and keyphrase extraction. To this end, features used in QPP are evaluated in keyphrase extraction using a naïve Bayes classifier. Our experiments indicate that these features improve the effectiveness of keyphrase extraction in documents of different length. More importantly, commonly used features of frequency and first position in text perform poorly on shorter documents, whereas QPP features are more robust and achieve better results. © 2012 The Author(s).
Open Access
KiMPA: A kinematics-based method for polygon approximation
(Springer, Berlin, Heidelberg, 2002) Şaykol, Ediz; Gülesir, Gürcan; Güdükbay, Uğur; Ulusoy, Özgür
In different types of information systems, such as multimedia information systems and geographic information systems, object-based information is represented via polygons corresponding to the boundaries of object regions. In many applications, the polygons have large number of vertices and edges, thus a way of representing the polygons with less number of vertices and edges is developed. This approach, called polygon approximation, or polygon simplification, is basically motivated with the difficulties faced in processing polygons with large number of vertices. Besides, large memory usage and disk requirements, and the possibility of having relatively more noise can also be considered as the reasons for polygon simplification. In this paper, a kinematics-based method for polygon approximation is proposed. The vertices of polygons are simplified according to the velocities and accelerations of the vertices with respect to the centroid of the polygon. Another property of the proposed method is that the user may set the number of vertices to be in the approximated polygon, and may hierarchically simplify the output. The approximation method is demonstrated through the experiments based on a set of polygonal objects. © Springer-Verlag Berlin Heidelberg 2002.
Open Access
A layout algorithm for undirected compound graphs
(Elsevier, 2009-03-15) Doğrusöz, Uğur; Giral, Erhan; Çetintaş, Ahmet; Civril, Ali; Demir, Emek
We present an algorithm for the layout of undirected compound graphs, relaxing restrictions of previously known algorithms in regards to topology and geometry. The algorithm is based on the traditional force-directed layout scheme with extensions to handle multi-level nesting, edges between nodes of arbitrary nesting levels, varying node sizes, and other possible application-specific constraints. Experimental results show that the execution time and quality of the produced drawings with respect to commonly accepted layout criteria are quite satisfactory. The algorithm has also been successfully implemented as part of a pathway integration and analysis toolkit named PATIKA, for drawing complicated biological pathways with compartmental constraints and arbitrary nesting relations to represent molecular complexes and various types of pathway abstractions. © 2008 Elsevier Inc. All rights reserved.
Open Access
Realistic rendering and animation of a multi-layered human body model
(IEEE, 2006) Yeşil, Mehmet Şahin; Güdükbay, Uğur
A framework for realistic rendering of a multi-layered human body model is proposed in this paper. The human model is composed of three layers: skeleton, muscle, and skin. The skeleton layer, represented by a set of joints and bones, controls the animation of the human body using inverse kinematics. Muscles are represented with action lines that are defined by a set of control points. An action line applies the force produced by a muscle on the bones and on the skin mesh. The skin layer is modeled as a 3D mesh and deformed during animation by binding the skin layer to both the skeleton and muscle layers. The skin is deformed by a two-step algorithm according to the current state of the skeleton and muscle layers. Performance experiments show that it is possible to obtain real-time frame rates for a moderately complex human model containing approximately 33,000 triangles on the skin layer. © 2006 IEEE.
Open Access
Stance detection: a survey
(Association for Computing Machinery, 2020) Küçük, D.; Can, Fazlı
Automatic elicitation of semantic information from natural language texts is an important research problem with many practical application areas. Especially after the recent proliferation of online content through channels such as social media sites, news portals, and forums; solutions to problems such as sentiment analysis, sarcasm/controversy/veracity/rumour/fake news detection, and argument mining gained increasing impact and significance, revealed with large volumes of related scientific publications. In this article, we tackle an important problem from the same family and present a survey of stance detection in social media posts and (online) regular texts. Although stance detection is defined in different ways in different application settings, the most common definition is “automatic classification of the stance of the producer of a piece of text, towards a target, into one of these three classes: {Favor, Against, Neither}.” Our survey includes definitions of related problems and concepts, classifications of the proposed approaches so far, descriptions of the relevant datasets and tools, and related outstanding issues. Stance detection is a recent natural language processing topic with diverse application areas, and our survey article on this newly emerging topic will act as a significant resource for interested researchers and practitioners.
Open Access
A “suggested” picture of web search in Turkish
(ACM, 2016-05) Sarıgil, E.; Yılmaz, O.; Altıngövde, İ. Ş.; Özcan, R.; Ulusoy, Özgür
Although query log analysis provides crucial insights about Web users’ search interests, conducting such analyses is almost impossible for some languages, as large-scale and public query logs are quite scarce. In this study, we first survey the existing query collections in Turkish and discuss their limitations. Next, we adopt a novel strategy to obtain a set of Turkish queries using the query autocompletion services from the four major search engines and provide the first large-scale analysis of Web queries and their results in Turkish.
Open Access
A Systematic mapping study on the current status of total cost of ownership for information systems
(Gazi Üniversitesi Bilişim Enstitüsü, 2018) Giray, G.; Tüzün, Eray
More and more organizations are being run dependent on information systems. This makes information systems a pivotal component of our lives. Because of globalization and harsh competition, strategic cost management has become essential to keep or gain competitive advantage. These two trends make the investigation of Total Cost of Ownership (TCO) for information systems crucial. To this end, a systematic mapping study (SMS) is presented to identify the use of TCO in information systems context. A summary of the findings after analyzing and synthesizing 75 relevant publications are as follows: (1) an increased interest in TCO for information systems is observed over the years; (2) 76% of the selected publications lack validation and evaluation; (3) the main motivation behind the 72% of the publications is reduction of TCO; (4) essential means of reducing TCO are cloud computing, SaaS model, and multi-tenancy; (5) TCO calculations are also generally made to compare cloud-based infrastructures with in-house infrastructures and SaaS model with on-premise software; (6) TCO is an important criterion in making investment decisions for information systems such as ERP, CRM.