Implementation of basic QoS mechanisms on videoconferencing network model

Ovo istraživanje je posljedica višegodišnjeg korištenja videokonferencijske veze te pojave raznih problema koji prate istu. Kašnjenje slike i zvuka, pucanje veze, prekid slike ili zvuka samo su neki od razloga zbog kojih je nastao ovaj rad. U ovom radu pokušava se primjenom mehanizama kvalitete usluge na modelu CARNet-ove mreže poboljšati kvaliteta videokonferencijske veze. Na osnovu dobivenih rezultata simulacije videokonferencijske veze prikazani su grafovi ispuštanja paketa, kašnjenja te ostalih parametara bitnih za videokonferencijsku vezu.This research is the outcome of multiannual use of videoconferencing services and the emersion of various problems that come with videoconferencing applications. Video and audio delay, dropped connection, missing audio or video, are just some of the reasons for creating this paper. In this article quality of videoconferencing link in CARNet network is improved by implementing various QoS mechanisms. The obtained results of the videoconferencing simulation are represented in graphs which display dropped packets, delay and other videoconferencing parameters

Multi-parameter structural transformations of passive electrical networks and natural frequency assignment

The paper examines the problem of systems redesign within the context of passive electrical networks by considering the problem of multi-parameter changes, their representation and impact on properties such as characteristic frequencies. The general problem area is the modelling of systems, whose structure is not fixed but evolves during the system lifecycle. The specific problem we are addressing is the study of effect of changing the topology of an electrical network that is changing individual elements of the network into elements of different type and value, augmenting / or eliminating parts of the network and developing a framework that allows the study of the effect of such transformations on the natural frequencies. This problem is a special case of the more general network redesign problem. We use the Impedance-Admittance models and we establish a representation of the different types of transformations on such models. For the case of network cardinality preserving transformations, we formulate the natural frequencies assignment problem as a problem of zero assignment of matrix pencils by additive structured transformations and this allows the deployment of the Determinantal Assignment Problem framework for the study of assignment and determination of fixed natural frequencies

System Properties of Implicit Passive Electrical Networks Descriptions

Redesigning systems by changing elements, topology, organization, augmenting the system by the addition of subsystems, or removing parts, is a major challenge for systems and control theory. A special case is the redesign of passive electric networks which aims to change the natural dynamics of the network (natural frequencies) by the above operations leading to a modification of the network. This requires changing the system to achieve the desirable natural frequencies and involves the selection of alternative values for dynamic elements and non-dynamic elements within a fixed interconnection topology and/or alteration of the interconnection topology and possible evolution of the network (increase of elements, branches). The use of state-space or transfer function models does not provide a suitable framework for the study of this problem, since every time such changes are introduced, a new state space or transfer function model has to be recalculated. The use of impedance and admittance modeling, provides a suitable framework for the study of network properties under the process of re-engineering transformations. This paper deals with the fundamental system properties of the impedance-admittance network description which provide the appropriate framework for network re-engineering. We identify the natural topologies expressing the structured transformations linked to the impedance-graph, admittance graph-topology of the network and examine issues such as network regularity, number of finite frequencies and provide characterization of them in terms of the basic network matrices. The implicit network representation introduced provides a natural framework for expressing the different types of re-engineering transformations which can be used for the study of the natural frequencies assignment

Old Aged Agricultural Holdings

crOCeSS °£,aging of rural, particularly of agricultural population in Yugo- • * ; g\u27 in Slavonia, East Serbia and within some ethnical groups in other w n i a a nr!Pm S\u27 C* ”biJela kuga<< venia and Croatia ,particularly in Istna, Dalmatia and Lik a( »thwehriet ei sp ae sltoinlegn ctrea«d)i.t iIonn Slolaf8fry° n a° f.oreigIconutries, while in Kosovo and Metohia and mountainous parts ot Macedonia, and Bosnia and Hercegovina there is a deeprooted tradition or seasonal »pečalba« (temporary employment far away from home). „ Uowever, for the process of aging of agricultural population the most decisive l rh• coasetluence? brought about by the industrialization of the country. First of all this has caused the large and mass spatial and socio-professional mobilitv younger generation from the coutryside, then the compulsory 8-year schooling and mass education for other occupations have stimulated the transfer from agriculture to other branches of economy. num . £n tbe! second part, the author — on the basis of the special demographic criteria — has selected 103 communities with 4.500 settlements where demographic Ih?^aH°rS Sf OW-tha- the Process of aging of rural population is in full swing E g the index of aging m many of these communities surpasses 0.5, in the commune Mimcevo it is even 1.2236. In some of these settlements every the third or the life1«? these tillages °f 6°\u27 WhiCh refiects a lot on economic and cultural o,it £“ 7S? thl? T?art ?^aut£?r interprets some results of the interview carried out m 7 2 6 aged households. These results point out the pecularity of the aged agricultural household in the social structure of the rural environment. ., e7i!nkri,S^ ^r,e *be resuits concerned with reasons of an origination of the aged households: 1) in more than 57.0% of the interviewed Luseholds des 3r?nani0S 1 P¥rated,or t liv£ °n jhejr own, 2) in 17.9% there were no descendants A q J o / V descendants had died or were killed during the last world war 4) m 9.6/o descendants were under the maturity age or in schools 5) in 4 2% of tie interviewed households descendants were not able to work Consecluently, this confirms the author’s thesis that the reason for a mass of aged agricultural households are numerous, but the socio-professional a™L pat3al mobility are the most decisive factors of the process of aging of rural particularly of agricultural population. S

The Yugoslav Community and Old Peasants

In this article the author describes the effects of the ageing of Yugoslavia’s peasant population. Yugoslavia\u27s population, especially that in rural districts, is becoming comparatively older. As a result there are an increasing number of villages where one out of three, or even every second inhabitant is over 60 years old. The natural increase in population is lower in rural districts than in towns. This is due to the large number of young people giving up agricultural work and leaving the villages. Yugoslav villages differ greatly in size and in the levels of social organization and urbanization. About one third of the villages are situated in mountain districts. The life of ageing peasants in these villages is becoming increasingly difficult. Their working ability is diminishing, they have to give up land cultivation, they no longer reconstruct or maintain their houses and farm buildings, etc. Social life is also declining in these villages. A certain proportion of young people are not prepared to look after their old parents, while some are unable to do so because of their own inadequate incomes. Changes in the way of life and in the traditional views and values have led to increasing individualism and a conflicting relationship between the generations. The traditional forms of family solidarity are dying out while new ones within society as a whole are not yet adequately developed. It is the old peasants who have become the victims of this transitional situation. (As defined by a peasant: »Before, we had to please our elders; now we have to please the younger generations. When are we going to live?«) The author calls for a speedy inclusion of peasants into the country’s collective system of health insurance and social welfare which covers the other categories of the population

Matrix pencil representation of structural transformations of passive electrical networks

The paper examines the problem of systems redesign within the context of passive electrical networks by considering the problem of multi-parameter and topology changes, and their representation. This representation may be used to investigate the impact of such changes on properties such as characteristic frequencies. The general problem area is the modelling of systems, whose structure is not fixed but evolves during the system life-cycle. The specific problem we are addressing is the study of effect of changing the topology of an electrical network that is changing individual elements of the network into elements of different type and value, augmenting / or eliminating parts of the network and developing a framework that allows the study of the effect of such transformations on the natural frequencies. This problem is a special case of the more general network redesign problem. We use the Impedance-Admittance models and we establish a representation of the different types of transformations on such models. The representation of the structural transformations is given in terms of the companion pencil that preserves the natural topologies of the RLC network

Kompresija slike korištenjem B-tree algoritma kodiranja poboljšan modeliranjem podataka Burrows-Wheeler transformacijom

The paper shows that the partial differential based compression framework, Edge Enhancing Diffusion Compression (EEDC) on high compression ratios can come close to or even be better than present compression standard - JPEG2000 thus presenting a novel method for image compression. In this paper EEDC will be enhanced by changing its data coding, i.e. Huffman coding will be changed with an entropy coder accompanied with Burrows-Wheeler transformation and context mixing. Images, graphs and tables show image compression results. The purpose of this article is to examine the effectiveness of the PDEs in image compression and to evaluate it by comparing to cosine and wavelet transform based compression methods.Ovaj rad pokazuje kako je kompresija temeljena na parcijalnim diferencijalnim jednadžbama, tj. EEDC na velikom stupnju kompresije dovoljno dobra ili čak bolja od trenutačnog kompresijskog standarda - JPEG2000 time predstavljajući novu metodu kompresije slika. U ovom radu EEDC je poboljšan tako da je promijenjeno kodiranje podataka svjetline slike, tj. Huffmanovo kodiranje je zamijenjeno entropijskim koderom i Burrows-Wheeler transformacijom s miješanjem konteksta. Slike, grafovi i tablice prikazuju rezultate kompresije slika. Svrha ovog rada je ispitati efikasnost parcijalnih diferencijalnih jednadžbi u kompresiji slike te ju usporediti metodama kompresije koje su bazirane na kosinusnoj i wavelet transformaciji