<p>Although a superconductor has zero resistivity when carrying a direct current, losses do occur when it is exposed to an alternating magnetic field and/or is carrying an alternating current. The magnitude of these so-called AC losses depends on the operating temperature, the amplitude and the direction of the magnetic field, the transport current, and the frequency. Therefore, the use of high-temperature superconductors, HTSs, in electric power components such as cables, transformers or reactors, requires knowledge of the AC losses.</p><p>This thesis deals with the development of AC loss models for HTSs, mainly for Bi-2223 tapes. In particular, the orientation of the applied magnetic field is taken into account in the modelling. The basis for the models is the results of experimental investigations.</p><p>The basic concepts of HTSs with special emphasis on the modelling of AC losses are presented. These can be broken down into several components. Their sources and natures are described. One of the components is the hysteretic loss and it is the dominating loss in AC applications at power frequencies. Therefore, the other loss components are neglected in the modelling.</p><p>Models are presented and the associated parameters are investigated with respect to their dependence of the magnetic field as well as the temperature. The AC losses for parallel and perpendicular magnetic field with respect to the wide side of the tape are calculated numerically. Moreover, a semi-empirical model for intermediate angels of the applied magnetic field is proposed. The comparisons show good agreement with experimental results.</p><p><b>Keywords:</b> High-temperature superconductors, AC loss modelling, hysteresis, E-J characteristic.</p>

A high resolution speedy delivery time domain reflectometer (SD/TDR) has been developed in the Electrical Engineering department at The University of Texas at Austin. The SD/TDR uses a novel non-sinusoidal signal that does not undergo dispersion during transmission in a lossy media. SD/TDR is used to estimate the length and detect the location of faults in the transmission lines. Time of flight (TOF) is one of the critical parameters of SD/TDR and a function of several temperature dependent factors. Given the TOF and length of a transmission line, signal delay can be computed. This research presents an empirical study of the effect of temperature on the TOF in a plenum grade coaxial cable for temperatures ranging from -3 °C to 60 °C. We also study the effect of temperature on characteristic impedance of the coaxial cable. Finally, a SD double exponential waveform is used to estimate TOF for calibrated short and open terminations. / text

The state of the art in artificial micro self assembly concepts are reviewed. The history of assembly is presented with a comparison to macro assembly, which has been widely studied, and micro self assembly. Criteria were developed and tested to show that macro assembly is more complex in ways that micro self assembly is not. Self assembly requirements for successful and complex self assembly, which evolved from the macro and micro comparison, are also established and tested. A method to assemble complex structures in the micro scale is proposed and demonstrated at the meso scale. The basic concepts of self assembly and a novel approach to complex multi layer self assembly is analyzed.

Modern mobile devices incorporate several transmit and receive antennas in highly constrained volumes. As miniaturized antennas impinge upon fundamental physical limits on efficiency, new design approaches are required to support ever-smaller devices with more varied and robust communication performance. We take an unconventional design approach in which an arbitrary metallic structure and its components can be modified to act as efficient radiators. Using eigenmode analysis and the theory of characteristic modes (TCM), we develop algorithms that allow for effective integration of antennas with mechanical structures and enable structure reuse, helping meet stringent space and weight constraints without sacrificing electromagnetic performance. We derive TCM-based objectives for effective exploration of the design space in the electromagnetic (EM) domain. The procedure includes a feed placement technique that identifies viable excitation points on the structure without running full EM analysis. In addition to computational advantages, this provides a point of comparison among a variety of antenna shapes. Empirical evaluation shows that the estimates of radiated power from TCM can effectively guide optimization toward structures with improved radiating properties. Automated feed placement increases the proportion of good-quality designs among the explored candidates by consistently selecting the most promising feed positions. The ability of the TCM-based algorithm to direct the search is further validated on two real-world applications: integration of a GPS antenna with the frame of a mobile phone and integration of an S-band antenna with the frame of a small spacecraft. To the best of our knowledge, this is the first work that applies TCM to automated optimization of antennas. We investigate how to leverage domain-specific methods and solution representations in the coupled optimization of antennas. We develop a novel multiobjective optimization framework based on local search in each domain. In this procedure, the local optima in each objective are obtained and modified to create a new population of candidate designs. On a number of benchmark problems, the proposed technique is competitive with leading multi-objective algorithms: while it finds a less uniform distribution along the Pareto front, it shows better performance in locating solutions at the boundaries of the tradeoff curve. The local search algorithm is successfully applied to topology optimization of an antenna for a CubeSat, a small low-cost satellite platform.

The novelty and originality of the work consists in the fact that in order to obtain asymptotic expansions with optimal values of the remainder terms in the zone of large deviations, along with the cumulant method the classical method of characteristic functions has to be used. In addition, when solving the problems stated in the work, other than the well known results in the problems of limit theorems of the probability theory and mathematical statistics, we have to estimate constants. Technically it is frequently rather a complicated task. The results obtained in the work have good opportunities to be applied in probability theory, mathematical statistics, econometric, etc. That is illustrated in the last section of the work in which theorems of large deviations are proved in the summation of weighted random variables with weights as well as discounted limit theorems.

Darbe gaunama, jog silpno matų konvergavimo erdvės X prasme išlpaukia charakteringųjų transformacijų konvergavimas ir atvirkščiai, jeigu charakteringosios transformacijos konverguoja į funkcijas tolydžias nuliniame taške, tai iš čia išplaukia matų silpnas konvergavimas erdvės X prasme. / It is obtained, that the weak convergence in the sense of X implies the convergence of characteristic transforms, and, on the contrary, if the characteristic transforms converge weakly to the functions contiuous at zero, the from this the weak convergence in the sense of X for the probability measures fallows.

It is an important step in clinical practice to discriminate real diseased patients from healthy persons. It would be great to get such discrimination from some common information like personal information, life style, and the contact with diseased patient. In this study, a score is calculated for each patient based on a survey through generalized linear model, and then the diseased status is decided according to previous sexually transmitted diseases (STDs) records. This study will facilitate clinics in grouping patients into real diseased or healthy, which in turn will affect the method clinics take to screen patients: complete screening for possible diseased patient and some common screening for potentially healthy persons.

One of the issues regarding the misclassification in case-control studies is whether the misclassification error rates are the same for both cases and controls. Currently, a common practice is to assume that the rates are the same (“non-differential” assumption). However, it is suspicious that this assumption is valid in many case-control studies. Unfortunately, no test is available so far to test the validity of the assumption of non-differential misclassification when the validation data are not available. We propose the first such method to test the validity of non-differential assumption in a case-control study with 2 × 2 contingency table. First, the Exposure Operating Characteristic curve is defined. Next, two non-parametric methods are applied to test the assumption of non-differential misclassification. Three examples from practical applications are used to illustrate the methods and a comparison is made.

Baigiamojo darbo tikslas yra išnagrinėti buitinių nužudymų kriminalistinės charakteristikos elementus ir nustatyti jos reikšmę nusikaltimų tyrimui. Buitinių nužudymų kriminalistinė charakteristika yra mokslinis teorinis modelis, apimantis tam tikrą informaciją, kurią naudojant galima pasiekti gerų tyrimo rezultatų. Iš tyčinių nužudymų, kaip atskirą nužudymų porūšį galime išskirti buitinius nužudymus, tai labiausiai paplitęs nužudymų porūšis. Buitinių nužudymų kriminalistinės charakteristikos struktūra sudaryta iš elementų, kurie išreikšti požymių visuma, atsispindinčių šio nužudymo porūšio elementuose, kurių pagrindu galima sudaryti atitinkamas prielaidas pasirenkant optimalius kriminalistinius metodus, priemones ir būdus nusikaltimų išaiškinimui, tyrimui. Buitinių nužudymų kriminalistinės charakteristikos sistemą, sudaro šie elementai: asmuo, padaręs buitinį nužudymą; buitinio nužudymo situacija; nukentėjusysis – nusikaltimo pasikėsinimo dalykas; buitinių nužudymų būdai. Praktinė buitinių nužudymų charakteristikos reikšmė yra tai, kad tyrėjas padaryto nužudymo atveju nustatęs net vieną ar keletą nužudymo elementų ir sulyginęs juos su turimomis tipinėmis nusikaltimų charakteristikomis gali sudaryti bendrą vaizdą apie tiriamą nusikaltimą, o tai palengvins jo atskleidimą. / The purpose of my degree work is the analysis of crime detection elements of household murders, as finding-out of his value for investigation of crimes. Crime detection analysis of household murders is scientific theoretical model containing some information, using which it is possible to reach good results in investigation. From deliberate crimes as separate subspecies of murders it is possible to allocate household murders which are the most widespread subspecies. The structure of household murders crime detection characteristics will consist of components, which means and ways for disclosing crimes are set of the attributes reflected in elements of subspecies of this murder on the basis of which it is possible to form corresponding preconditions choosing optimum crime detection methods, their investigation. The system of household murders crime detection characteristics, in my opinion, should consist of the following elements: the person who has made household murder; a situation of household murder; suffering - as object of a crime; ways of fulfillments of household murders. Practical value of the characteristic of household murders will be, that the inspector in case of the committed murder having established one or several elements of murder and having compared them with available typical characteristics of murders, can make the general opinion on the perfect crime, that will facilitate his investigation.

The aim of the study - to investigate interaction regularities of water flow energy distribution and stream beds during the naturalization process, to identify morphometric changes in the beds of streams and to assess the impact of these factors on the ecological status of rivers. To achieving this aim, 6 specific tasks were identified: 1 Designing geostatistical models of hydromorphological characteristics of regulated and natural river beds based on the field research results; 2 Identifying morphometric characteristics of river beds based on geostatistical models; 3 Determining regularities of the flow energy distribution and its interaction with the stream bed; 4 Determining the abundance and composition of grass and woody vegetation in the investigated sections of streams; 5 Determining the diversity, composition and abundance of macrozoobenthos and fish species; 6 Identifying the impact of flow energy distribution and stream bed interaction on the ecological status of rivers. / Darbo tikslas – ištirti vandens tėkmės energijos pasiskirstymo ir upelių vagų sąveikos dėsningumus, vykstant natūralizacijos procesams, nustatyti morfometrinius pokyčius upelių vagose lemiančius veiksnius ir įvertinti jų poveikį upių ekologinei būklei. Darbo tikslui pasiekti buvo sprendžiami 6 uždaviniai: 1) taikant natūrinių tyrimų rezultatus, sudaryti geostatistinius reguliuotų ir natūralių vagų hidromorfologinių charakteristikų modelius; 2) pasinaudojus gautais modeliais, nustatyti morfometrines vagų charakteristikas; 3) pasinaudojus gautais modeliais, išsiaiškinti tėkmės energijos pasiskirstymo ir jos sąveikos su upelių vaga dėsningumus; 4) ištirti žolinės ir sumedėjusios augalijos gausą ir jos sudėtį tiriamų upelių atkarpose; 5) nustatyti makrozoobentoso ir juo besimaitinančių žuvų rūšinę įvairovę, sudėtį ir gausą; 6) išsiaiškinti tėkmės energijos pasiskirstymo ir upelių vagų sąveikos įtaką upių ekologinei būklei.