Željka Car

Stochastic modeling of signal propagation in power-line communication networks

Signal propagation through power-line networks has been studied by a number of researchers. Among a number of propagation models described in literature, deterministic models based on actual physical description of the network can be constructed as both very accurate and very efficient in computational terms. Yet they have an inherent drawback of being suitable for propagation analyses in static conditions and steady state only. Thus, our main research problem was how to extend a deterministic frequency-domain-based propagation model for a more practically useful modeling of channels of multi-port power-line communication networks. We have concentrated on a particular model that we presented in an earlier literature. Our main findings are as follows: Computationally efficient deterministic models can be utilized for stochastic simulations in multi-port power-line network environments by repeating the propagation simulation routine virtually as many times as needed, to model the network parameter variability by appropriate stochastic modeling of termination impedances connected to each of the multiple network ports. In this way, an extended set of physical properties of the channel can be simulated and statistically analyzed, such as the complex transfer function, impulse response, delay spread, and group delay. Copyright

Mannosylated N-Aryl Substituted 3-Hydroxypyridine-4-Ones: Synthesis, Hemagglutination Inhibitory Properties, and Molecular Modeling

Structural alterations of the aglycon portions of α‐mannosides influence their inhibitory potency toward type 1‐fimbriated Escherichia coli. The aim of our work was to prepare and explore inhibitory properties of novel mannosylated N‐aryl‐substituted 3‐hydroxypyridine‐4‐ones because they possess needed structural characteristics as possible FimH antagonists. Hemagglutination inhibitory tests showed that the examined 3‐hydroxypyridine‐4‐one α‐mannosides exhibited better inhibitory activity than methyl α‐d‐mannopyranoside used as a reference compound. Molecular modeling studies revealed the specific interactions responsible for the observed binding activities toward the mannose‐specific FimH lectin. The activity depends on the substituent in p‐position on the aglycon aromatic ring.

Software verification process improvement proposal using six sigma

In the rapidly growing modern telecommunications industry, software quality and reliability requirements are in contrast to the shorter time to market and higher complexity requirements dictated by strong competition on the telecommunication market. In such a rapidly changing environment, software development organization must improve almost on a daily basis in order to achieve the operational excellence which leads to business success. In this paper, an approach to the continuous improvement of the software verification process based on the application of Six Sigma is given. More precisely, with the help of the Six Sigma methodology, change management, and statistical tools and techniques, the proposed approach solves the problem of fault slippage through verification phases, which is particularly important in overlapping project conditions. Success of the proposed process improvement, proved using Six Sigma methodologies for a case study from a real industrial project, encourages wide and general application to any software verification process.

A quality cost reduction model for large-scale software development

Understanding quality costs is recognized as a prerequisite for decreasing the variability of the success of software development projects. This paper presents an empirical quality cost reduction (QCR) model to support the decision-making process for additional investment in the early phases of software verification. The main idea of the QCR model is to direct additional investment into software units that have some fault-slip potential in their later verification phases, with the aim of reducing costs and increasing product quality. The fault-slip potential of a software unit within a system is determined by analogy with historical projects. After a preliminary study on a sample of software units, which proves that we can lower quality costs with additional investment into particular verification activities, we examine the effectiveness of the proposed QCR model using real project data. The results show that applying the model produces a positive business case, meaning that the model lowers quality costs and increases quality, resulting in economic benefit. The potential to reduce quality costs is growing significantly with the evolution of software systems and the reuse of their software units. The proposed model is the result of a research project performed at Ericsson.

e-Accessible service system: calibrator and communicator

Augmentative and Alternative Communication (AAC) includes various communication methods used by people with speech and language impairments, and is often aided by electronic devices such as smartphones or tablets. Since skills and limitations vary for each user, it is possible to create an interface on these electronic devices that would adjust to users needs in ways that would significantly improve usability and ease of use. Paper describes e-Accessible service system containing Calibrator and Communicator services. Calibrator measures users preferences and limitations regarding user interface through calibration process and calculates UI parameters adapted to the particular user. The parameters are forwarded to the Communicator service, whose main purpose is to supplement speech or writing for people with complex communication needs.

Synthesis and Enzymic Hydrolysis of Acylated Adenosine Derivatives

Abstract Various derivatives of adenosine were prepared by acylation of adenosine (6‐amino‐9‐(β‐D‐ribofuranosyl)purine (1) with different molar equivalents of acetic anhydride and/or pivaloyl chloride in pyridine. Compounds 6‐acetylamino‐9‐[(2,3,5‐tri‐O‐acetyl)‐β‐D‐ribofuranosyl]purine (3), 6‐amino‐9‐[(2,3,5‐tri‐O‐acetyl)‐β‐D‐ribofuranosyl]purine (4), and 6‐pivaloylamino‐9‐[(2,3,5‐tri‐O‐pivaloyl)‐β‐D‐ribofuranosyl]purine (5) were subsequently submitted to hydrolysis catalyzed by a number of hydrolytic enzymes. Regioselective enzymic deacetylation at the primary hydroxyl group of 3 and 4 with butyrylcholinesterase (BChE) produced 6‐acetylamino‐9‐[(2,3‐di‐O‐acetyl)‐β‐D‐ribofuranosyl]purine (9) and 6‐amino‐9‐[(2,3‐di‐O‐acetyl‐β‐D‐ribofuranosyl]purine (10), respectively. All structures were established by 1H and 13C NMR spectroscopies.

Introducing session on ICT-Based alternative and augmentative communication

Persons with complex communication needs are individuals who are unable to use speech as their primary method of communication. Reasons for complex communication needs differ widely, such as physical and/or intellectual impairment, Down syndrome, Autistic Spectrum Disease etc. Alternative and augmentative communication (AAC) is based on the use of graphic and textual symbols to represent certain objects, actions, or concepts. AAC has been proven as highly beneficial for improving speech, literacy, learning, employment, and quality of life for persons with complex communication needs. ICT-based AAC services refer to services that enable symbol-based human-to-human and human-to-machine communication in a computer and networking environment.

Synthesis of Acylated Methyl 2‐Acetamido‐2‐Deoxy‐α‐D‐Mannopyranosides

Abstract 2‐Acetamido‐2‐deoxy‐β‐D‐mannopyranose (1) was glycosylated by the Fischer method using an acidic ion‐exchange resin as the catalyst to give α‐methyl glycoside 2. Selective pivaloylations of methyl 2‐acetamido‐2‐deoxy‐α‐D‐mannopyranoside (2) have been studied under various reaction conditions. Two partially pivaloylated products were submitted to additional acetylations. All structures were established by NMR spectroscopy. Structure of the methyl 2‐acetamido‐2‐deoxy‐3,6‐di‐O‐pivaloyl‐α‐D‐mannopyranoside (4) was determined by X‐ray analysis.

Requirements and Architecture Modeling in Software Engineering Courses

Modeling of requirements and software architecture involves abstraction and critical reasoning that is the most complex stage of development. This knowledge area is the hardest for students to acquire within computer science curricula. The main problem is the fact that the full understanding of this knowledge may only be visible while developing and evolving large scale complex software systems. The learning strategy may have significant impact on students ability to capture this knowledge. On the other hand, we may need different learning strategies depending on the context of study programme and students knowledge base. Here, in this paper, we present different strategies taken within software engineering courses but in different study programme context. We discuss lessons learned from two courses that belong to two different study programmes at Croatian Universities. Also, the deviate learning strategies involving approach and modeling tools and techniques used in these courses are different.

User interface adaptation for ICT based alternative and augmentative applications

Original scientific paper Support of ICT in Alternative and Augmentative Communication (AAC) has been recognized as the key enabler of better inclusion of persons with complex communication needs into everyday life. Due to complex, and often very individual, communication needs, such persons need the ability to quickly adapt graphical user interfaces according to their needs, skills, impairments and possibilities. The paper proposes initial automatic adaptation of AAC application user interfaces that is performed only once and then distributed across AAC applications through a specialized AAC platform. The adaptation is formally specified using timed Petri nets and evaluated on a group of users, aiming at producing components that can be re-used without the need for further evaluation, thus enabling rapid development of new applications without the need for real user testing, due to the nature and availability of AAC users. Finally, the paper proposes several methods of choosing symbols and weighs the benefits of each method according to evaluation results.