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Harmonized requirements apply for the marketing authorization of medicinal products in the EU Member States. On the contrary, the national legislations on the drug reimbursement are not harmonized. The aim of this study was to find out if they are robust enough to ensure high standards of public health protection with focus on the symptomatic treatment of dementia in the elderly. A computerized search of authorized therapeutic indications of haloperidol and trihexyphenidyl in the national databases of 8 EU member states and an analysis of the national legislation on reimbursement policies in Lithuania and Latvia was performed. There is a discrepancy in the decisions on the marketing authorization vs the reimbursement in Lithuania and Latvia (reimbursement of haloperidol and trihexyphenidyl for the off-label treatment of dementia). National legislation on the drug reimbursement in Lithuania and Latvia does not provide safeguards for public health at the same level as the marketing authorization does. Absence of a revision of former decisions in the light of new evidence is a critical weakness of the drug reimbursement in Lithuania and Latvia. Reimbursement for the off-label indications may pose a risk to public health.

Objective. There are well-documented reports of cisplatin-associated hyponatremia in the literature, but there are no data on gender-dependent differences. The aim of the present study was to define characteristics of 24-hour urinary sodium excretion in young adult Wistar rats of both genders and to evaluate the gender-related effect of cisplatin. Materials and methods. Twelve control Wistar rats (6 males and 6 females) and 12 cisplatintreated Wistar rats (6 males and 6 females) after a single and repeated injection of cisplatin (once a day for 3 days) at a dose of 2.5 mg/kg body weight into the caudal vein were examined. The experiment was carried out by measuring 24-h urinary sodium, potassium, chloride, magnesium, creatinine excretion and pH in the urine of age-matched male and female rats. Results. The 24-h urinary sodium excretion, sodium/chloride ratio, and diuresis showed no gender-related differences in control rats. After a single administration of 2.5 mg/kg cisplatin, 24-h urinary sodium excretion was not significantly higher in cisplatin-treated rats than in gender-matched controls. After repeated cisplatin administration, 24-h urinary sodium excretion was significantly higher in cisplatin-treated male rats as compared to matched controls (P&lt, 0.05). No such effect was found in cisplatin-treated female rats. Conclusion. The study data show that cisplatin enhances urinary sodium excretion in male but not in female rats. The mechanism of such a gender-related effect is not yet clear. Further investigations are necessary to elucidate the mechanism of this pharmacological effect of cisplatin.

Darbe nagrinėjama priverstinės sinchronizacijos sistema, sudaryta iš n generatorių, kurių vienas (vedantysis) priverstinai sinchronizuoja (n−1) sujungtų į žiedą valdomų generatorių. Šiai sistemai sudarytas matematinis modelis, gautos pereinamųjųu funkcijų matricos elementų tikslios analizinės išraiškos., The forced synchronization system compared of n oscillators (n = 4, 6, 8) is analysed. Exact analytical expressions for elements of the step responsesmatrix of the system are derived.

Depression is one of the leading causes of disability worldwide, affecting 121 million people in whole world. In many developed countries, the number of prescriptions for antidepressants increased steeply during the 1990s. The objective of the present study was to evaluate the antidepressant prescribing patterns in all regions of Lithuania during 2003–2004, to analyze the use within different antidepressant groups, and to examine trends in age- and gender-specific antidepressant use. Antidepressants were classified into three groups according to Anatomic Therapeutic Chemical (ATC) Classification specifying the defined daily doses. The results of our study show an increase in the use of reimbursed antidepressants except tricyclic in 2004 when compared to 2003. Increase in the use of selective serotonin reuptake inhibitors and other nontricyclic antidepressants is probably related to their better tolerability, improved risk-benefit ratio, and less toxicity in overdose. There was no increase in the percentage of consumed selective serotonin reuptake inhibitors in elderly patients when compared with younger ones, despite elderly patients are most likely to benefit from reduced sedation, less antimuscarinic and less cardiac toxicity of selective serotonin reuptake inhibitors. The prevalence of the antidepressant use is the highest among middle-aged people (40–59 years), while the young (under 20) and elderly (older than 70) patients receive mostly selective serotonin reuptake inhibitors. Additional studies should be carried out in order to assess drug-prescribing patterns in accordance with the guidelines of depression treatment in Lithuania considering diagnosis, dosage, and duration of treatment.

Breastfeeding is the most healthful method of feeding neonates and infants. In 2001 about 98% of new mothers in Lithuania started breastfeeding their neonates. One-third of nursing women (34%) discontinued breastfeeding at the time when infant reached the age of 3 months. About 56% of women breastfed their infants longer than 4 months. Only 3–6% of nursing women discontinued breastfeeding after the fourth month. Discontinuation of breastfeeding in 21–23% of all cases was directly or indirectly associated with use of medications. Such data suggest that there is a lack of information often leading physicians to advise mothers to discontinue breastfeeding because of medication use. The aim of this article was to survey the situation about classification of drugs used during breastfeeding and factors influencing drug transfer into milk in order to give more information for physician concerning the use of medication during breastfeeding. In this review, a short description of main pharmacokinetic characteristics, influencing drug transfer into milk; information on the classification of drugs used during breastfeeding; some considerations on drug safety and possible adverse effects of medications on breastfed infant; the list of drugs preferred for nursing women are presented.

Antipsychotic drugs have been used clinically for approximately 50 years. Reserpine and chlorpromazine were first drugs found be useful in schizophrenia. The term “antipsychotic” is used to describe a group of drugs that has been used mainly for treating of schizophrenia, but also is effective in some other psychoses and agitated states. The dopamine hypothesis is the most fully developed of several hypothesis and is the basis for rational drug therapy. However, the dopamine hypothesis is far from complete. Typical antipsychotic drugs have a wide spectrum of central nervous system, autonomic and endocrine effects. The most recently introduced antipsychotics are at least as potent in inhibiting 5-HT receptors as they are in inhibiting D receptors. A rational choice of antipsychotic drugs may be based on differences between chemical structures and pharmacological differences. No basis exists for choosing drugs for the use against selected target symptoms, as there is no evidence of specificity in their effects.

Aim of the study: To compare safety and efficacy of combined hormonal contraceptives and assess what factors influence choice of combined hormonal contraceptives Research objectives: 1. Analyze information about efficacy and safety of combined hormonal contraceptives. 2. Analyze and identify efficacy and safety differences between different combined hormonal contraceptives. 3. Assess what factors causes choice of combined hormonal contraceptives. Methodology: Questionnaire-based survey of customers buying combined hormonal contraceptives in pharmacies was carried out. 346 respondents were questioned in total. Statistical analysis of data was carried out by means of SPSS program package (Version 22.0). Statistical links were assessed by means of Pearson χ2 compatibility criteria. Outcome: 70.2% respondents have chosen contraceptive pills, 20.2 % - contraceptive ring, 9.6 % - contraceptive patch. It was found that what factors are the most important depends on social factors (age, education, marital status, number of children, earnings) and chosen contraception method. Efficacy is the most important factor for contraceptive ring users. Doctor‘s recommendations are the most important for contraceptive ring users who are older and have higher education. Acceptability is the most important for contraceptive patch users who are not married. Price is the most important for contraceptive pills users who have secondary education, are not married, have children and minimal earnings. Side effects are the most important for contraceptive ring users who have high education, have children and big earnings. Conclusions: 1. In theory, combined hormonal contraceptives efficacy reaches 99 %, but in practice it is less. Considering that serious side effects are rare, combined hormonal contraceptives benefits outweigh the risks. 2. The main safety and efficacy differences of combined hormonal contraceptives are venous tromboembolism, arterial thrombosis and androgenic effects, which are dependent from type of progestin and level of estrogen. Efficacy of different combined hormonal contraceptives is very similar. 3. The most important factors influencing preference to select combined hormonal contraceptives are: efficacy (the most important factor and it’s not dependent from any social factors or contraceptive method). Doctor‘s recommendations (significance is dependent from education and contraceptive method; p

Aim: Analyze dangerous drug interactions and interactions with others substances in ambulatory care practice and reveal the pharmacist role in order to avoid them. Tasks: 1. Choose dangerous drug interactions from analyzed scientific literature in pursuance to reveal pharmacist role in avoiding them. 2. Estimate practical role of pharmacist with on the basis of analyzed anonymous questionnaire. Objectives and methods: The participants of the research project – pharmacists working in community pharmacies, patients taking statins and patients taking ACE inhibitors. Test method – an anonymous questionnaire. In total there were 230 questionnaires distributed to pharmacists, 179 questionnaires were returned fully completed (response rate 77,80proc.). In total there were distributed 550 questionnaires to patients, 406 questionnaires were returned fully completed (response rate 73,50 proc.). The statistical analysis was performed using SPSS (Statistical Package for Social Science) 17.0 Results: 39 % of respondents are taking ACE inhibitors with potassium supplements. 14 % of respondents are taking statins with grapefruits. About possible drug interaction know about 50 % of patients who are taking ACE inhibitors or statins. 89 % of pharmacists claim that they inform patients about drug interaction, but according to patients – 21-34 % of them know about interactions from pharmacists. Those pharmacists who work in cities or those who work longer than 21 years know and inform less about drug interactions than those, who work in cities or work less than 5 years. Pharmacists who read SPC know about drug interaction 2,4 times more. Patient knowledge about drug interaction increase about 25 % when pharmacists inquire patient what drug they are taking. Conclusion:1.According to drug consumption and literature common drug interactions are ACE inhibitors with potassium supplements and statins with grapefruit or grapefruit juice components. 2. Pacients knowledge about drug interactions is not sufficient – about 50 proc. of patient who are taking ACE inhibitors or statins knows about drug interaction. Too much of patients (39 %) are taking ACE inhibitors with potassium supplements. 3. Pharmacists role is not sufficient despite that they can significantly take part in avoiding drug interaction: pharmacists inquire half of patients if they are taking additiniol drugs or supplements. Almost half of the patients who are taking ACE inhibitors consume potassium supplements. Consumption of this combination increase with age. 4. SPC reading and patients inquiring about additional drug or supplement consumption improve pharmacist role in avoiding drug interactions.

Aim: Perform analysis of the literature about new pharmacotherapeutic groups – sodium – glucose co-transporter inhibitors (SGLT-2), a dipeptidyl peptidase-4 inhibitors (DPP-4) and incretin mimetic (GLP-1) drugs for diabetes, to assess their advantages and disadvantages compared with older groups and to assess patient satisfaction. Tasks: to get acquainted with the features in various phases in type 2 diabetes mellitus treatment, perform analysis of scientific literature in order to compare new and older pharmacotherapeutic group of drugs for type 2 diabetes mellitus advantages and disadvantages, perform for diabetes patients a questionnaire survey to compare satisfaction with the treatment of different pharmacotherapeutic gruop of drugs for type 2 diabetes. Object – old and new generation of pharmacotherapeutic group antidiabetic drugs. Methods: A questionnaire based survey for lithuanian patients of second type diabetes was carried out. The obtained data was fed into Excel 2015 spreadsheet and analyzed by statistical software package SPSS 21.0 Results: DPP-4 inhibitors stand out with the greatest health satisfaction (49,2 %) but with GLP- 1 mimetics health satisfaction is much lower (42,1 %). The lowest health satissfaction was associated with sulphonylurea monotherapy (35.7%). The DPP-4 inhibitors in treatment combinations is associated with the greatest satisfaction with insufficient glycemic control (with the Met - 67.2%, SK - 74.2%, MET + SK - 64.6%) and the lowest – with the use of GLP-1 in combination with MET and MET + SK combination (respectively 55.6% and 52.9%). With sulphonylurea as monotherapy or in combination with GLP-1 mimetics and DPP-4 inhibitors hypoglycaemia occurred more frequently. Less incidence of hypoglycaemia is related with metofrmin both in monotherapy and in combinations. DPP-4 inhibitors and GLP-1 added to the therapy did not increase the incidence of hypoglycemia. In most cases, respondents as symptoms of hypoglycaemia identify weakness (38.1%), sweating (13.4%) and tremor (11.5%). Conclusions: 1. Based on the results and the literature, a new generation of drugs (GLP-1 mimetics, DPP-4 inhibitors) compared with a sulphonylurea with lower frequency of hypoglycaemia, and better health evaluation, is associated better treatment satisfaction. 2. DPP-4 inhibitors is associated with the highest satisfaction with treatment. 3. Metformin is associated with greater treatment satisfaction than GLP-1 mimetics and sulphonylureas. 4. Respondents' knowledge of hypoglycemia is very poor, and this can lead to poor treatment safety, and worse treatment satisfaction. Practical recommendations: encourage patients to visit coureses for diabetes patients to provide information about: diabetes, its complications; hypoglycaemia risk of taking a drug, what it is and how to recognize it. Physician in selecting the patient medication should take into consideration the satisfaction of one or another drug to be expected.

Remiantis sinchronizacijos sistemos struktūrine schema sudaromas jos matematinis modelis – matricinė diferencialinė lygtis su vėluojančiu argumentu. Ši lygtis yra sprendžiama nuoseklaus integravimo metodu ir gauti rezultatai lyginami su rezultatais gautais metodu, paremtu dde23 funkcijos taikymu. Sprendžiant matricinę diferencialinę lygtį nuoseklaus integravimo metodu intervalas dalijamas į vėlavimo ilgio dalinius intervalus ir kiekviename intervale lygtis sprendžiama atskirai, kaip matricinė diferencialinė lygtis be vėluojančio argumento. Ieškodami sprendinio kiekviename intervale, taikome Laplaso transformaciją. Naudojantis matricinės diferencialinės lygties su vėluojančiu argumentu sprendiniu, išvedame sinchronizacijos sistemos pereinamųjų funkcijų ir generatorių virpesių fazių skirtumų analizines išraiškas. Remiantis gautomis išraiškomis atliekame pereinamųjų procesų tyrimus., Time delay is often encountered in various technical systems, such as electric, pneumatic and hydraulic networks, chemical processes, long transmission lines, robotics, etc. The existence of pure time lag, regardless if it is present in the control or/and the state, may cause undesirable system transient response, or even instability. The aim of this work is to investigate the mutual synchronization system, composed of five oscillators. The mathematical model of the synchronization system is the matrix differential equation with delayed argument. It is solved applying the Laplase transformation method. Using this method the analytical expressions for step responses and differences between phases are found. The results of consequent integration method are compared with the results got using method with dde23 function.

Darbe nagrinėjama ryšio tinklo tarpusavio sinchronizacijos sistema, sudaryta iš penkių į grandinę sujungtų generatorių. Darbo tikslas – sudaryti sinchronizacijos sistemos matematinį modelį, rasti sistemos pereinamųjų funkcijų ir generatorių virpesių fazių skirtumų tikslias analizines išraiškas, ištirti sistemos pereinamuosius procesus ir jos darbą nusistovėjusiame režime. Nagrinėjamos tarpusavio sinchronizacijos sistemos matematinis modelis – matricinė diferencialinė lygtis su vėluojančiu argumentu. Šią lygtį sprendžiame taikant Laplaso transformaciją ir „žingsnių“ metodą. Remdamiesi surastu sprendiniu, randame sinchronizacijos sistemos pereinamųjų funkcijų, vidinių ryšių struktūrą nusakančios matricos ir generatorių virpesių fazių skirtumų tikslias analizines išraiškas. Remiantis sinchronizacijos sistemos pereinamosiomis funkcijomis, tiriami sistemos pereinamieji procesai, atsirandantys įjungus sistemos generatorių valdymą., The mathematical model of the synchronization system composed of five joined into a chain oscillators is investigated. The mathematical model of the synchronization system is the system of matrix differential equation with delayed arguments. The solution of the matrix differential equation is obtained applying the Laplace transform and the “steps“ method. The analytical expressions of the system‘s step response functions, the matrix and the phase differences of the oscillators are obtained. Steady values of the step response functions and steady values of the phase differences are obtained applying the limiting value theorem. The transition processes of the system with equal and different delays are investigated.

Darbe nagrinėjama ryšio tinklo sinchronizacijos sistema, sudaryta iš keturių tarpusavyje sinchronizuotų generatorių. Darbo tikslas - sudaryti sinchronizacijos sistemos matematinį modelį, rasti sistemos pereinamųjų funkcijų ir generatorių virpesių fazių skirtumų tikslias analizines išraiškas, ištirti sistemos pereinamuosius procesus ir jos darbą nusistovėjusiame režime. Nagrinėjamos sistemos matematinis modelis - matricinė diferencialinė lygtis su vėluojančiu argumentu. Ši lygtis sprendžiama „žingsnių“ metodu. Tuo tikslu intervalas dalijamas į vienodo ilgio dalinius intervalus. Kiekviename daliniame intervale lygtis sprendžiama atskirai, kaip paprasta matricinė diferencialinė lygtis be vėluojančio argumento. Naudojantis gautu sprendiniu, rastos tikslios sinchronizacijos sistemos pereinamųjų funkcijų analizinės išraiškos. Remiantis šiomis išraiškomis, atliktas pereinamųjų procesų sinchronizacijos sistemoje tyrimas. The mutual synchronization system of the communication network, composed of four oscillators, is investigated in the work. Following aims were raised in this work: to compose the mathematical model of the synchronization system, to find the exact expressions of the step responses of the system and of the phase differences of the oscillations of oscillators, to investigate the transients in the synchronization system. The mathematical model of the system is the matrix differential equation with delayed argument. This equation is solved applying the method of consequent integration (method of “steps”). For this purpose the interval is divided to subintervals of equal length. The equation in each subinterval is solved separately, as ordinary differential equation without delayed argument. Using obtained expression of the solution, the expressions of step responses of the system are got. The expressions of step responses are applied investigating the transients in the synchronization system.

Darbe nagrinėjama ryšio tinklo sinchronizacijos sistema, sudaryta iš keturių tarpusavyje sinchronizuotų generatorių. Darbo tikslas - sudaryti sinchronizacijos sistemos matematinį modelį, rasti sistemos pereinamųjų funkcijų ir generatorių virpesių fazių skirtumų tikslias analizines išraiškas, ištirti sistemos pereinamuosius procesus ir jos darbą nusistovėjusiame režime. Nagrinėjamos sistemos matematinis modelis - matricinė diferencialinė lygtis su vėluojančiu argumentu. Ši lygtis sprendžiama „žingsnių“ metodu. Tuo tikslu intervalas dalijamas į vienodo ilgio dalinius intervalus. Kiekviename daliniame intervale lygtis sprendžiama atskirai, kaip paprasta matricinė diferencialinė lygtis be vėluojančio argumento. Naudojantis gautu sprendiniu, rastos tikslios sinchronizacijos sistemos pereinamųjų funkcijų analizinės išraiškos. Remiantis šiomis išraiškomis, atliktas pereinamųjų procesų sinchronizacijos sistemoje tyrimas., The mutual synchronization system of the communication network, composed of four oscillators, is investigated in the work. Following aims were raised in this work: to compose the mathematical model of the synchronization system, to find the exact expressions of the step responses of the system and of the phase differences of the oscillations of oscillators, to investigate the transients in the synchronization system. The mathematical model of the system is the matrix differential equation with delayed argument. This equation is solved applying the method of consequent integration (method of “steps”). For this purpose the interval is divided to subintervals of equal length. The equation in each subinterval is solved separately, as ordinary differential equation without delayed argument. Using obtained expression of the solution, the expressions of step responses of the system are got. The expressions of step responses are applied investigating the transients in the synchronization system.

Disertacijoje nagrinėjama interneto tinklo infrastruktūros patikimumo problematika, analizei naudojant tinklo topologijos tyrimus, grafų teorijos taikymą ir tinklo modeliavimą. Tyrimų objektas, interneto tinklo infrastruktūra, kurios pagrindą sudaro autonominės sistemos ir tarptinklinių sujungimų linijos. Nuo stabilios interneto tinklo veiklos priklauso informacijos pasiekiamumas, elektroninė komercija, nutolusių objektų valdymas ir t. t. Pagrindinis disertacijos tikslas – sukurti metodikas ir algoritmus, skirtus interneto tinklo infrastruktūros analizei bei veiklos patikimumo kontrolei. Tyrimų taikymo sritis – interneto tinklo veiklos tęstinumo priežiūra ir reguliavimas. Darbe sprendžiami šie pagrindiniai uždaviniai: interneto tinklo topologijos analizės modelio ir priemonių sudarymas; interneto junglumo tyrimas siekiant identifikuoti kritinius elementus, kurių pažeidimai susiję su tinklo funkcionalumo praradimu; kritinių interneto tinklo elementų stebėsenos modelio sudarymas; eksperimentiniai kibernetinių atakų simuliacijos bandymai; bei interneto tinklo infrastruktūros patikimo stiprinimo parinkimas. Disertaciją sudaro įvadas, 5 skyriai, rezultatų apibendrinimas, naudotos literatūros ir autoriaus publikacijų disertacijos tema sąrašai bei priedai. The dissertation investigates the issues of dependability of the Internet network infrastructure that were studied by using the network topology analysis, graph theory and network modelling. The object of the study is the Internet network infrastructure, based on autonomous systems and interconnecting lines. Stable functioning of the Internet network determines the availability of information, electronic commerce, control of remote objects, etc. The main objective is to develop the methodologies and algorithms for analysing the Internet network infrastructure and controlling the reliability of functioning. The scope of application of the study is the supervision and regulation of continuity of the Internet. The following main tasks are solved: development of the topological scheme of the Internet network, selection of models and tools for analysis; the Internet network connectivity analysis for the purpose of identification of the critical network elements, whose violations would result in loss of connectivity of the network; as well as development of the model for monitoring of the critical elements of the Internet network and cyber-attacks simulation experiments. The scientific work consists of the general characteristic of the dissertation, 5 chapters, conclusions, list of literature, list of publications and annexes.

Disertacijoje nagrinėjama belaidės prieigos tinklų savybės, gebėjimas kontroliuoti ir užtikrinti paslaugos kokybę (QoS) bei stebėti ją vartotojų įrenginiuose. Darbo tikslas – ištirti belaidės prieigos tinklų darbo parametrų įtaką paslaugos kokybei ir sukurti apibendrintą paslaugos kokybės stebėsenos priemonių, taikomų galutinio vartotojo įrenginyje, modelį. The dissertation investigates wireless access network performance, ability to control and enforce quality of service (QoS) and track it at user device. The objective of presented research is to investigate wireless access network performance parameter impact on quality of service and develop reference model of QoS monitor, applied for end-user device.

The dissertation investigates wireless access network performance, ability to control and enforce quality of service (QoS) and track it at user device. The objective of presented research is to investigate wireless access network performance parameter impact on quality of service and develop reference model of QoS monitor, applied for end-user device. In order to reach the objective, the following tasks had to be solved: - To analyze existing measures of QoS evaluation, actual achieved, perceived QoS monitoring and Service Level Agreement (SLA) enforcement. - To analyze performance properties of contemporary wireless user access network technologies in order to determine their capabilities providing data services and employing soft and hard QoS mechanisms. - To analyze network performance characteristics in order to determine factors, influencing quality of service in wireless access networks. - To design principles of evaluation of actually achieved quality of service. - To develop a reference model of QoS requirement composition and monitoring system. - To develop and experimentally test QoS monitor for web browsing service. First chapter of the dissertation reviews QoS definitions, categories, existing methods of QoS evaluation and formulates the problem of QoS and service level agreement enforcement measures. Second chapter presents analysis of various access networks applicable to data and voice services. The analysis is focused on available bit rate, referred to... [to full text] Disertacijoje nagrinėjama belaidės prieigos tinklų savybės, gebėjimas kontroliuoti ir užtikrinti paslaugos kokybę (QoS) bei stebėti ją vartotojų įrenginiuose. Darbo tikslas – ištirti belaidės prieigos tinklų darbo parametrų įtaką paslaugos kokybei ir sukurti apibendrintą paslaugos kokybės stebėsenos priemonių, taikomų galutinio vartotojo įrenginyje, modelį. Šiam tikslui pasiekti, sprendžiami tokie uždaviniai: - Išanalizuoti esamas paslaugos kokybės vertinimo, realiai patirtos ir suvokiamos kokybės stebėsenos bei paslaugų lygmens susitarimų (SLA) užtikrinimo priemones. - Išanalizuoti dabartinių belaidžių vartotojo prieigos technologijų savybes teikiant duomenų perdavimo paslaugas ir taikant griežtus bei švelnius paslaugos kokybės užtikrinimo mechanizmus. - Išanalizuoti belaidžių prieigos tinklų charakteristikas siekiant nustatyti faktorius, įtakojančius paslaugos kokybę belaidžiuose prieigos tinkluose. - Suformuluoti realiai pasiektos paslaugos kokybės vertinimo principus. - Sukurti apibendrintą paslaugos kokybės reikalavimų sudarymo ir stebėsenos sistemos vartotojo įrenginyje modelį. - Sukurti ir eksperimentiškai įvertinti paslaugos kokybės stebėsenos sistemą interneto naršymo paslaugai. Pirmajame disertacijos skyriuje pateikiama žinomų paslaugos kokybės vertinimo ir valdymo procesų apžvalga, koncentruojantis į vartotojo perspektyvą ir galimybes įvertinti realiai gaunamą ir vartotojo suvokiamą paslaugų kokybę. Antrajame skyriuje pateikiama paplitusių belaidės prieigos tinklų... [toliau žr. visą tekstą]

Disertacijoje nagrinėjami GSM kanale vykstantys balso paketų praradimai. Nagrinėjama galimybė vertinti trumpų balso segmentų kokybę PESQ algoritmu. Pasiūlomas naujas, mažos trukmės balso signalų kokybės vertinimo PESQ algoritmu metodas. Pristatomas originalus balso kokybės vertinimo metodas mobiliojo ryšio sistemoms, paremtas balso kokybės klasėmis. Thesis presents the research of voice frame losses in the GSM. The possibility of evaluation of quality of short duration signals using PESQ algorithm is analysed. New method for preparation of short duration signals for PESQ measurements is proposed. Original method based on quality classes for voice quality evaluation in mobile communications is presented.

Thesis presents the research of voice frame losses in the GSM. The possibility of evaluation of quality of short duration signals using PESQ algorithm is analysed. New method for preparation of short duration signals for PESQ measurements is proposed. Original method based on quality classes for voice quality evaluation in mobile communications is presented. Disertacijoje nagrinėjami GSM kanale vykstantys balso paketų praradimai. Nagrinėjama galimybė vertinti trumpų balso segmentų kokybę PESQ algoritmu. Pasiūlomas naujas, mažos trukmės balso signalų kokybės vertinimo PESQ algoritmu metodas. Pristatomas originalus balso kokybės vertinimo metodas mobiliojo ryšio sistemoms, paremtas balso kokybės klasėmis.

Topicality of the problem. Wireless WAN technologies which can provide multimedia services to customer in most cases are implemented by the commercial providers of voice services. Thus technologies are expensive in development of the Hot-Spots, where volatile expanded concentration of customers may be observed. For such purposes the main alternative technologies are the IEEE 802.11. In modern telecommunications industry the expansion of the IEEE 802.11 networks is one of the fastest growing segment of the telecommunications market. This technology has quickly found a significant place and popularity to provide the typical services of Internet in business, home networking, and etc. Growing evolution of Internet technologies determines transmitted data flows to take a shape of specific real time multimedia flows features. For such conditions the IEEE 802.11 general technology was not adapted. It is important to develop the new operation methods based on IEEE 802.11 without changing main standard specification. This method lets to adopt an existing in market equipment of IEEE 802.11 for multimedia or voice flows. The methodology of IEEE 802.11 technological expenditures influence estimation, presented in dissertation, has not been used before. This estimation method allows to evaluate rationality of physical resource utilization and to predict protocol modification directions. Also, method of synchronous voice communication in customer access is proposed. This solution allows... [to full text] Mokslo problemos aktualumas. Plačiajuostės licencijuojamų dažnių bevielės technologijos, kurios paprastai skirtos vartotojams teikti komercines multimedijos ir balso paslaugas, yra per brangios vystant prieigos tinklus, kuriuose sutinkama didelė vartotojų koncentracija. Dėl to šios technologijos dažniausiai naudojamos tik komercinių balso paslaugų tiekėjų. Labiausiai tinkama alternatyva – yra IEEE 802.11 technologijos, kurių naudojimas modernių telekomunikacijų tinklų išplėtimui įvairiose tipinėse sąlygose yra pastebimai auganti telekomunikacijų rinkos dalis. Ši technologija greitai išplito ir tapo populiari verslo, namų, „paskutinės mylios“ ir kituose tinklų vystymo sprendimuose. Modernėjant Interneto technologijoms, telekomunikacijų tinkluose įsivyrauja multimedijos požymių turintys srautai, kurių sukurtoms specifinėms sąlygoms IEEE 802.11 technologijos nėra pritaikytos. Todėl svarbu kurti naujus, ribines galimybes išnaudojančius, bet specifikacijos nekeičiančius protokolus, kurie leistų rinkoje esančią įrangą adaptuoti realaus laiko srautams. Disertacijoje naudojama IEEE 802.11 MAC protokolo technologinių sąnaudų įtakos vertinimo metodika nebuvo taikoma. Šis vertinimo būdas leidžia įvertinti fizinio resurso užėmimo racionalumą ir numatyti IEEE 802.11 protokolo modifikavimo kryptis. Pateiktas sinchroninis vartotojų prieigos adaptacijos balso perdavimams būdas leidžia racionaliai panaudoti IEEE 802.11 protokolą balsui adaptuotose vartotojų prieigose. Todėl, galima teigti... [toliau žr. visą tekstą]

Mokslo problemos aktualumas. Plačiajuostės licencijuojamų dažnių bevielės technologijos, kurios paprastai skirtos vartotojams teikti komercines multimedijos ir balso paslaugas, yra per brangios vystant prieigos tinklus, kuriuose sutinkama didelė vartotojų koncentracija. Dėl to šios technologijos dažniausiai naudojamos tik komercinių balso paslaugų tiekėjų. Labiausiai tinkama alternatyva – yra IEEE 802.11 technologijos, kurių naudojimas modernių telekomunikacijų tinklų išplėtimui įvairiose tipinėse sąlygose yra pastebimai auganti telekomunikacijų rinkos dalis. Ši technologija greitai išplito ir tapo populiari verslo, namų, „paskutinės mylios“ ir kituose tinklų vystymo sprendimuose. Modernėjant Interneto technologijoms, telekomunikacijų tinkluose įsivyrauja multimedijos požymių turintys srautai, kurių sukurtoms specifinėms sąlygoms IEEE 802.11 technologijos nėra pritaikytos. Todėl svarbu kurti naujus, ribines galimybes išnaudojančius, bet specifikacijos nekeičiančius protokolus, kurie leistų rinkoje esančią įrangą adaptuoti realaus laiko srautams. Disertacijoje naudojama IEEE 802.11 MAC protokolo technologinių sąnaudų įtakos vertinimo metodika nebuvo taikoma. Šis vertinimo būdas leidžia įvertinti fizinio resurso užėmimo racionalumą ir numatyti IEEE 802.11 protokolo modifikavimo kryptis. Pateiktas sinchroninis vartotojų prieigos adaptacijos balso perdavimams būdas leidžia racionaliai panaudoti IEEE 802.11 protokolą balsui adaptuotose vartotojų prieigose. Todėl, galima teigti... [toliau žr. visą tekstą] Topicality of the problem. Wireless WAN technologies which can provide multimedia services to customer in most cases are implemented by the commercial providers of voice services. Thus technologies are expensive in development of the Hot-Spots, where volatile expanded concentration of customers may be observed. For such purposes the main alternative technologies are the IEEE 802.11. In modern telecommunications industry the expansion of the IEEE 802.11 networks is one of the fastest growing segment of the telecommunications market. This technology has quickly found a significant place and popularity to provide the typical services of Internet in business, home networking, and etc. Growing evolution of Internet technologies determines transmitted data flows to take a shape of specific real time multimedia flows features. For such conditions the IEEE 802.11 general technology was not adapted. It is important to develop the new operation methods based on IEEE 802.11 without changing main standard specification. This method lets to adopt an existing in market equipment of IEEE 802.11 for multimedia or voice flows. The methodology of IEEE 802.11 technological expenditures influence estimation, presented in dissertation, has not been used before. This estimation method allows to evaluate rationality of physical resource utilization and to predict protocol modification directions. Also, method of synchronous voice communication in customer access is proposed. This solution allows... [to full text]

The paper is devoted to statistical nonparametric estimation of multivariate distribution density. The influence of data pre-clustering on the estimation accuracy of multimodal density is analysed by means of the Monte-Carlo method.

The mutual synchronization system composed of four oscillators is analysed in the work. The matrix differential equation with delayed arguments is the mathematical model of the synchronization system. The solution of the matrix differential equation is obtained applying the method of “steps” and Laplace transform. The solution involves the powers of the matrix describing the structure of internal links of the synchronization system. The powers of this matrix are calculated taking into account the eigenvalues and eigenvectors of the matrix. Applying solution of the matrix differential equation the step responses matrix of the system is obtained and transient responses are analysed. The dependence of the phase differences of the oscillators on initial conditions is analysed.

There are numerous synchronization methodologies available in solving the problem of network synchronization. This paper presents an analytical analysis of the mathematical model of forced synchronization system composed of four oscillators. Exact analytical and graphical expressions of transition functions and exact expressions of the phase differences between signals of oscillators of this synchronization system are obtained.

SUMMARY There are numerous methodologies available in solving the problem in synchronizing timing oscillators of the communication networks: pleziosynchronization, forced synchronization or mutual synchronization. In the presented work the mutual synchronization system composed of four oscillators is analyzed. The mathematical model of the synchronization system is matrix differential equation with delayed argument. Applying the method of “steps” and Laplace transform we find the solution of the matrix differential equation and the step responses matrix of the synchronization system. Exact analytical and graphical expressions of transition functions and exact expressions of the phase differences between signals of oscillators of this synchronization system are obtained.

The mutual synchronization system composed of four oscillators is analysed in the work. The matrix differential equation with delayed arguments is the mathematical model of the synchronization system. The solution of the matrix differential equation is obtained applying the method of “steps” and Laplace transform. The solution involves the powers of the matrix describing the structure of internal links of the synchronization system. The powers of this matrix are calculated taking into account the eigenvalues and eigenvectors of the matrix. Applying solution of the matrix differential equation the step responses matrix of the system is obtained and transient responses are analysed. The dependence of the phase differences of the oscillators on initial conditions is analysed.

There are numerous synchronization methodologies available in solving the problem of network synchronization. This paper presents an analytical analysis of the mathematical model of forced synchronization system composed of four oscillators. Exact analytical and graphical expressions of transition functions and exact expressions of the phase differences between signals of oscillators of this synchronization system are obtained.

The mutual in the synchronization system is analyzed in this work. The mutual in the synchronization is a double – side synchronization of interdependent tactical oscillators. Every of interdependent oscillators has influence on the frequency of other oscillators. The frequency of all oscillators will be the same and equal to the certain medium frequency which depends upon, the frequency and distances among separate oscillators of all in the settled regime of them joined into the net. The objective of the work is to analyze the synchronization system which is joined of four interdependent oscillators. The mathematical model of synchronization system is formed, analytic expressions of transitional function and differences among phases of oscillation are set transitional processes of synchronization system and differences among phases of oscillation are researched. The mathematical model of synchronization system is matrixal rectilinear dif. Equation with the argument to be late. It is solved using the method of steps and the transformation of Laplace. Exact analytical expressions of the solution components are found using Jordan’s form of descriptive matrix which describes the structure of inherent relations among the blocks of the system analytical expressions of transitional functions in the system and differences of phases of oscillation are obtained on the basis of the solution.

The mathematical model of the forced synchronization system, composed of four oscillators is investigated. The mathematical model of the system is the matrix differential equation with delayed arguments. The matrix differential equation is solved using method of steps and applying Laplace transform. Using this method and exact solution of the matrix differential equation with delayed arguments was obtained and exact expressions of the elements of the step responses matrix, of the synchronization system are got. On the base of derived formulas the transition processes of the system are investigated.

The mutual in the synchronization system is analyzed in this work. The mutual in the synchronization is a double – side synchronization of interdependent tactical oscillators. Every of interdependent oscillators has influence on the frequency of other oscillators. The frequency of all oscillators will be the same and equal to the certain medium frequency which depends upon, the frequency and distances among separate oscillators of all in the settled regime of them joined into the net. The objective of the work is to analyze the synchronization system which is joined of four interdependent oscillators. The mathematical model of synchronization system is formed, analytic expressions of transitional function and differences among phases of oscillation are set transitional processes of synchronization system and differences among phases of oscillation are researched. The mathematical model of synchronization system is matrixal rectilinear dif. Equation with the argument to be late. It is solved using the method of steps and the transformation of Laplace. Exact analytical expressions of the solution components are found using Jordan’s form of descriptive matrix which describes the structure of inherent relations among the blocks of the system analytical expressions of transitional functions in the system and differences of phases of oscillation are obtained on the basis of the solution.