Faculty of Computer Science and Engineering

Permanent URI for this communityhttps://repository.ukim.mk/handle/20.500.12188/5

The Faculty of Computer Science and Engineering (FCSE) within UKIM is the largest and most prestigious faculty in the field of computer science and technologies in Macedonia, and among the largest faculties in that field in the region. The FCSE teaching staff consists of 50 professors and 30 associates. These include many “best in field” personnel, such as the most referenced scientists in Macedonia and the most influential professors in the ICT industry in the Republic of Macedonia.

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Improving the QRS detection for one-channel ECG sensor
(SAGE Publications, 2019-11-07)
Domazet, Ervin
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We analyzed several QRS detection algorithms in order to build a quality industrial beat detector, intended for a small, wearable, one channel electrocardiogram sensor with a sampling rate of 125 Hz, and analog-to-digital conversion of 10 bits. The research was a lengthy process that included building several hundred rules to cope with the QRS detection problems and finding an optimal threshold value for several parameters. We obtained 99.90% QRS sensitivity and 99.90% QRS positive predictive rate measured on the first channel of rescaled and resampled MIT-BIH Arrhythmia ECG database. Even more so, our solution works better than the algorithms for the original signals with a sampling rate of 360 Hz and analog-to-digital conversion of 11 bits.
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A new model for cloud elastic services efficiency
(Informa UK Limited, 2018-02-09)
Ristov, Sasko
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Mathá, Roland
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Kimovski, Dragi
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Prodan, Radu
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The speedup measures the improvement in performance when the computational resources are being scaled. The efficiency, on the other side, provides the ratio between the achieved speedup and the number of scaled computational resources (processors). Both parameters (speedup and efficiency), which are defined according to Amdahl’s Law, provide very important information about performance of a computer system with scaled resources compared with a computer system with a single processor. However, as cloud elastic services’ load is variable, apart of the scaled resources, it is vital to analyse the load in order to determine which system is more effective and efficient. Unfortunately, both the speedup and efficiency are not sufficient enough for proper modeling of cloud elastic services, as the assumptions for both the speedup and efficiency are that the system’s resources are scaled, while the load is constant. In this paper, we extend the scaling of resources and define two additional scaled systems by (i) scaling the load and (ii) scaling both the load and resources. We introduce a model to determine the efficiency for each scaled system, which can be used to compare the efficiencies of all scaled systems, regardless if they are scaled in terms of load or resources. We have evaluated the model by using Windows Azure and the experimental results confirm the theoretical analysis. Although one can argue that web services are scalable and comply with Gustafson’s Law only, we provide a taxonomy that classifies scaled systems based on the compliance with both the Amdahl’s and Gustafson’s laws. For three different scaled systems (scaled resources R, scaled load L and combination RL), we introduce a model to determine the scaling efficiency. Our model extends the current definition of efficiency according to Amdahl’s Law, which assumes scaling the resources, and not the load.
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Design specification of an ECG mobile application
(IEEE, 2017-11)
Domazet, Ervin
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The latest developments in IoT, have brought upon new innovations in that space. Electronic health solutions are among these innovations. Statistics indicate that cardiovascular diseases are the primary cause of deaths globally. Our knowledge about this type of diseases shows that specific types of heart attacks can be prevented. Real-time acquisition and processing using wearable biosensors can enable the detection of cardiac symptoms at an early stage. The concept of mHealth is defined as the combination of current state of the technology and the telecommunications infrastructure, in order to provide healthcare services. This paper contributes to such solutions by provisioning generic design specifications of an ECG mobile application.
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Enhancing and simulating the RIP routing protocol in cloud
(IEEE, 2014-11)
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Ristov, Sasko
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Network routers use dynamic routing protocols to learn remote networks automatically. Each routing protocol has its own pros and cons when considering administration, maintenance, metrics, convergence time, backup routes, network complexity and size, scalability, resource requirements and so on. RIP is the simplest routing protocol, which is supported by almost all routers and many operating systems, but has several deficiencies, such as emerging routing loops and slow convergence. In this paper, we develop a new idea by enhancing RIP in order to to reduce its deficiencies. The cloud environment is used to develop and monitor the enhanced RIP's packets. The packets were monitored successfully, and remote networks were discovered by using them. Additionally, changes were done in the Wireshark packet analyzer in order to recognize the enhanced RIP's packets.
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Max-log-MAP decoding with reduced memory complexity
(IEEE, 2015-09)
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Given an M-state (recursive) convolutional encoder and information sequence of length n, the space complexity of unoptimized Bahl-Cocke-Jelinek-Raviv (BCJR) decoder is considered to be O(nm). However, if BCJR's forward alpha coefficients are continuously recomputed instead of stored in memory, it can be shown that the space complexity will drop to O(m). In this paper we start from these observations and present a technique for memory reduction in the Max-Log-MAP algorithm. We test our design on a rate-1/2 1025-bit-long Turbo Code and show considerable memory saving.
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Scalable architecture of e-ordering system in cloud
(IEEE, 2015-05)
Dimitrievski, Filip
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Ristov, Sasko
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Todays dynamic economy enforces the companies to dismiss their minor-business departments and to turn the efforts towards the main business. This is emphasized especially to small and start-up companies, which would like to order the issues as a service from third parties as OPEX (Operational Expenditure), rather than investing in their own departments as CAPEX (Capital Expenditure). Even more, they expect to achieve their orders as faster as possible. Since the number of such companies is floating, as well as the number of their employees, these requirements demand a scalable system for e-ordering. Such a system will allow the consumer companies to order some services from the sellers. In this paper we present scalable architecture in the cloud, which can be offered as a service both to the consumers (buyers) and clients (sellers), along with two business models according to the market in a particular region or state.
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Scalable system for e-orders as a service in cloud
(IEEE, 2015-09)
Ristov, Sasko
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Dimitrievski, Filip
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Cloud market grows each year and companies' dilemma is when and where to migrate their services and applications. Companies can migrate the whole application together with its data, or move only data to some application or service that is already prepared in the cloud. Companies have challenges in either way. For the former, the company should redevelop its application to be applicable to the cloud architecture of the cloud service provider, while it should develop some adapter or make some data transformation for the latter. This paper focuses on the migration of the application along with its data and presents the development of scalable and portable system for e-ordering, which can be offered as a service in the cloud. The system orchestrates the resources dynamically and groups buyers and sellers according to the needs, thus reducing the database size and optimizing the cost and performance. Series of experiments are conducted to prove the scalability of the system hosted in the scalable Eucalyptus cloud framework. The results show a phenomenon, that is, superlinear improvement (greater than the scaled resources) of the performance while scaling the resources. The new architecture achieves speedup of up to 20 while scaling the resources only with factor four. Also, superlinearity appears in the number of handled requests.
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E-Testing question development technologies and strategies
(IEEE, 2015-03)
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Ristov, Sasko
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Advanced learning technologies integrate questions as a very relevant function in building e-Testing systems and especially in intelligent tutoring systems. Therefore, a huge challenge is the generation of a necessary and relevant assessment content. The existing efforts to realize open source learning materials and establishment of massive open online courses introduce another challenge for realization of a sophisticated system and appropriate knowledge database with huge number of questions reflecting all relevant knowledge items (learning objectives). In this paper we present the experience in realization of a real e-Testing system by building two variations: the first with standard graphical interface, and the other with an enhanced media interaction supporting interactive images. We present several question generation strategies for conventional approach using multiple-choice questions and also for the system with interactive images. These techniques can be used to develop a large set of questions and assessment content.
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Technologies for Interactive Learning and Assessment Content Development
(IGI Global, 2016-01-01)
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Ristov, Sasko
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<p>Recent technology trends evolved the student assessment from traditional ones (“pen-and-paper” and “face-to-face”) to modern e-Assessment system. These modern approaches allow the teachers to conduct and evaluate an exam with huge number of students in a short period of time. Even more important, both the teacher and the students achieve the evaluation results immediately after the assessment has finished. Although the e-Assessment system speeds up the evaluation, teachers face a huge challenge to prepare, organize and generate a huge set of questions. The questions must cover all learning objectives and their number should be as large as possible to prevent cheating by guessing or memorization of correct answers from previous exams. This paper presents several technologies that can efficiently realize strategies to develop a huge question database with minimal teacher efforts. It also describes the methodologies and strategies based on a specific technology. The technologies are categorized in two classes of e-Assessment systems that are used at the authors' faculty: the traditional e-Assessment system with usual multiple-choice answers and the newest e-Assessment system with interactive images. The question generation is based on defining the questions and answers as XML files (for more advanced users) and MS Word-based files (for users with basic IT background). The question database can be used both for efficient and effective e-Assessment and e-Learning.</p>
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Interoperability of ECG standards
(IEEE, 2018-05)
Stamenov, Dejan
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The increased demand for interoperability of electronic health records leads to the need for establishing reliable standards for storing and retrieving electrocardiogram data. Multiple medical record data standards were created in response to medical organization initiatives, based on binary and XML formats. These standards raise the need to maximize interoperability between systems that share ECG datasets. HL7 aECG, SCP-ECG, DICOM, and ISHNE are among the most popular ECG standards, which are compared within this paper. We have implemented an adapter system - ECGConvert, which provides interoperability on raw ECG to HL7 aECG and SCP-ECG, while also supporting ISHNE format to HL7 aECG conversion. We provide a discussion for the interoperability of these standards in the healthcare, the problems we have faced and solution to improve the process of sharing ECG datasets between organizations. Our interoperability platform can support the wearable ECG devices that provide single-channel ECG streaming data. The metadata raw ECG record can be converted to any of currently used ECG standards by the built prototype.

Faculty of Computer Science and Engineering

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