Projektovanje i ispitivanje struktura baza podataka u upravljanju održavanjem vazduhoplovanih sistema

Visoki zahtevi koji se postavljaju sistemu za odrzavanje vazduhoplova izmedu ostalog zahtevaju temeljnu analizu postojece strategije odrzavanja i njeno znacajno unapredenje. Savremeni sistemi odrzavanja obuhvataju i upravljanje odrzavanjem, tj. zasnovani su na automatizovanoj podrsci odrzavanju primenom racunara (Computer Integrated Maintenance Management). U osnovi automatizovane podrske odrzavanju primenom racunara je model podataka. Veoma je vazno da je model podataka dovoljno bogat da bi mogao, na relativno lak nacin prihvatiti i u sebe ukljuciti razlicite koncepte realnog sistema zajedno sa svojim atribu- tima i medusobnim vezama. Hijerarhijske strukture podataka (strukture podataka tipa stablo) su posebno interesantne u sistemu odrzavanja vazduhoplova i one su predmet istrazivanja u ovom radu. Postavlja se sledeci zahtev. Obezbediti takvu implementaciju hijerarhijske struk- ture koja pruza mogucnost njene ekasne obrade. Rekurzija koja je u osnovi hijerarhijske strukture podataka odnosno stabla koji je reprezent ovakve strukture podataka, moze biti problem u ekasnom upravljanju sistemom odrzavanja vazduhoplova. U radu su date nove karakterizacije stabla, koje daju osnov za nerekurzivne modele hijerarhijske strukture poda- taka. U kontekstu ogranicenih resursa u sistemu za odrzavanje vazduhoplova posebno su intere- santne optimalne strategije odrzavanja. Bitan segment sistema za upravljanje odrzavanjem je planiranje odrzavanja. Jedan od osnovnih problema izmedu ostalog je neizvesnost dogadaja koji znacajno uticu na samo planiranje. Rec je o dogadajima koji su po svojoj prirodi slucajni. Posebno analizira se planiranje odrzavanja u slucaju kada skup aktivnosti ima hijerarhijsku strukturu i pri tome je trajanje pojedinih aktivnosti iz datog skupa aktivno- sti slucajna velicina. Pod pretpostavkom da aktivnost na visem nivou hijerarhije ne moze zapoceti pre nego sto su zavrsene sve aktivnosti na nizem nivou hijerarhije i da su poznati gubici koji nastaju u slucaju da se sa nekim aktivnostima kasni, odnosno da su poznati gu- bici u slucaju da su neke aktivnosti preuranjene, potrebno je formirati optimalnu strategiju aktiviranja aktivnosti iz datog skupa. U slucaju hijerarhije visine jedan problem se svodi na poznati newsboy problem, ali je u opstem slucaju isuvise komplikovan. U radu se predlaze heuristicki pristup kojim se do resenja dolazi iterativnom primenom jednostavnog resenja problema na dvononiovskoj hijerarhiji. Vazduhoplovi su savremena saobracajna sredstva vrhunske tehnologije sa velikim bro- jem komponenti i kompleksnom strukturom. Pojedine komponente vazduhoplova se koriste na razlicit nacin, trpe razlicita opterecenja i odrzavaju po programu koji je njima najbolje prilagoden. Jedan od nacina savladavanja slozenosti je takozvana hijerarhijska dekompozi- cija. Slozeni koncept se na jednom nivou apstrakcije posmatra kao jedinstvena celina. Na nizem nivou apstrakcije se posmatra kao koncept koji se sastoji od delova (komponenti). Uzastopnom primenom opisanog postupka dobija se takozvana hijerarhijska sastavnica. Da- kle jedan od bitnih koncepata u sistemu odrzavanja vazduhoplova jeste sastavnica. Poseban problem je obezbediti kvalitetan sadrzaj hijerarhijske strukture podataka, odnosno u sistemu za upravljanje odrzavanjem vazduhoplova treba obezbediti kvalitetnu sastavnicu. U radu je predlozena eksibilna struktura sastavnica koja u velikoj meri podrzava njeno sadrzajno rasirenje...The high demands that are placed to aircraft maintenance systems among other things require thorough analysis of existing maintenance strategy and its signicant improvement. Modern maintenance systems include the management of maintenance, i.e. they are based on automated maintenance support by computer - Computer Integrated Maintenance Mana- gement. The basic component in automated maintenance support account is data model. It is important that the data model is rich enough to accept in a relatively easy way a variety of real system concepts together with their attributes and interrelations. Hierarchical data structure ( textit tree type data structure) are of special interest in the aircraft maintenance systems, and they are the subject of this study. This raise the following request. Implement hierarchical data structure which allows ecient processing. Recursion which is essential in implementation of hierarchical data structure, i.e., of the tree, which is typical representative of these data structures, can be a problem in ecient aircraft maintenance management. This study gives a new characterizations of tree, which provide a basis for nonrecursive models of hierarchical data structures. In the context of limited resources in the aircraft maintenance systems, optimal mainte- nance strategies are of special interest. An important segment of the maintenance manage- ment system is maintenance planning. One of the major problems is uncertainty of events which signicantly aect maintenance planning. These events are random by its nature. In particular, the planning of maintenance is analyzed in the case when the set of activities has a hierarchical structure and duration, of each activity from a given set of activities, is random value. Assuming that the activity at a higher level of hierarchy can not begin before the completion of all activities at a lower level of hierarchy, and that losses incurred in the case of delayed activities, i.e., losses incurred in the case of premature activity are known, it is necessary to establish optimal activating strategy for each activity from given set of activities. In the case of one level hierarchy, problem is reduced to the well known newsboy problem, but it is too complicated in general. In this study, a heuristic approach is proposed for the solution of general problem that is based on iterative application of the solution of a simple two levels hierarchy problem. Aircrafts are modern high-tech means of transport with a large number of components and complex structure. Components of aircraft are used in dierent ways, they suer dierent loads and are maintained by the programs that are best suited for them. One way to overcome this complexity is so-called hierarchical decomposition. Complex concept at one level of abstraction is seen as unied. At the lower level of abstraction it is seen as a concept that consists of parts (other components). Repeated application of described procedure gives the so-called hierarchical bill of material. So one of the important concepts in the aircraft maintenance systems is bill of material. A particular problem is to provide quality hierarchical data structures to the aircraft maintenance management system, i.e., to provide quality bill of material. This study proposes a exible structure of the bill of material which greatly supports disseminate its content..

Projektovanje i ispitivanje struktura baza podataka u upravljanju održavanjem vazduhoplovanih sistema

Visoki zahtevi koji se postavljaju sistemu za odrzavanje vazduhoplova izmedu ostalog zahtevaju temeljnu analizu postojece strategije odrzavanja i njeno znacajno unapredenje. Savremeni sistemi odrzavanja obuhvataju i upravljanje odrzavanjem, tj. zasnovani su na automatizovanoj podrsci odrzavanju primenom racunara (Computer Integrated Maintenance Management). U osnovi automatizovane podrske odrzavanju primenom racunara je model podataka. Veoma je vazno da je model podataka dovoljno bogat da bi mogao, na relativno lak nacin prihvatiti i u sebe ukljuciti razlicite koncepte realnog sistema zajedno sa svojim atribu- tima i medusobnim vezama. Hijerarhijske strukture podataka (strukture podataka tipa stablo) su posebno interesantne u sistemu odrzavanja vazduhoplova i one su predmet istrazivanja u ovom radu. Postavlja se sledeci zahtev. Obezbediti takvu implementaciju hijerarhijske struk- ture koja pruza mogucnost njene ekasne obrade. Rekurzija koja je u osnovi hijerarhijske strukture podataka odnosno stabla koji je reprezent ovakve strukture podataka, moze biti problem u ekasnom upravljanju sistemom odrzavanja vazduhoplova. U radu su date nove karakterizacije stabla, koje daju osnov za nerekurzivne modele hijerarhijske strukture poda- taka. U kontekstu ogranicenih resursa u sistemu za odrzavanje vazduhoplova posebno su intere- santne optimalne strategije odrzavanja. Bitan segment sistema za upravljanje odrzavanjem je planiranje odrzavanja. Jedan od osnovnih problema izmedu ostalog je neizvesnost dogadaja koji znacajno uticu na samo planiranje. Rec je o dogadajima koji su po svojoj prirodi slucajni. Posebno analizira se planiranje odrzavanja u slucaju kada skup aktivnosti ima hijerarhijsku strukturu i pri tome je trajanje pojedinih aktivnosti iz datog skupa aktivno- sti slucajna velicina. Pod pretpostavkom da aktivnost na visem nivou hijerarhije ne moze zapoceti pre nego sto su zavrsene sve aktivnosti na nizem nivou hijerarhije i da su poznati gubici koji nastaju u slucaju da se sa nekim aktivnostima kasni, odnosno da su poznati gu- bici u slucaju da su neke aktivnosti preuranjene, potrebno je formirati optimalnu strategiju aktiviranja aktivnosti iz datog skupa. U slucaju hijerarhije visine jedan problem se svodi na poznati newsboy problem, ali je u opstem slucaju isuvise komplikovan. U radu se predlaze heuristicki pristup kojim se do resenja dolazi iterativnom primenom jednostavnog resenja problema na dvononiovskoj hijerarhiji. Vazduhoplovi su savremena saobracajna sredstva vrhunske tehnologije sa velikim bro- jem komponenti i kompleksnom strukturom. Pojedine komponente vazduhoplova se koriste na razlicit nacin, trpe razlicita opterecenja i odrzavaju po programu koji je njima najbolje prilagoden. Jedan od nacina savladavanja slozenosti je takozvana hijerarhijska dekompozi- cija. Slozeni koncept se na jednom nivou apstrakcije posmatra kao jedinstvena celina. Na nizem nivou apstrakcije se posmatra kao koncept koji se sastoji od delova (komponenti). Uzastopnom primenom opisanog postupka dobija se takozvana hijerarhijska sastavnica. Da- kle jedan od bitnih koncepata u sistemu odrzavanja vazduhoplova jeste sastavnica. Poseban problem je obezbediti kvalitetan sadrzaj hijerarhijske strukture podataka, odnosno u sistemu za upravljanje odrzavanjem vazduhoplova treba obezbediti kvalitetnu sastavnicu. U radu je predlozena eksibilna struktura sastavnica koja u velikoj meri podrzava njeno sadrzajno rasirenje...The high demands that are placed to aircraft maintenance systems among other things require thorough analysis of existing maintenance strategy and its signicant improvement. Modern maintenance systems include the management of maintenance, i.e. they are based on automated maintenance support by computer - Computer Integrated Maintenance Mana- gement. The basic component in automated maintenance support account is data model. It is important that the data model is rich enough to accept in a relatively easy way a variety of real system concepts together with their attributes and interrelations. Hierarchical data structure ( textit tree type data structure) are of special interest in the aircraft maintenance systems, and they are the subject of this study. This raise the following request. Implement hierarchical data structure which allows ecient processing. Recursion which is essential in implementation of hierarchical data structure, i.e., of the tree, which is typical representative of these data structures, can be a problem in ecient aircraft maintenance management. This study gives a new characterizations of tree, which provide a basis for nonrecursive models of hierarchical data structures. In the context of limited resources in the aircraft maintenance systems, optimal mainte- nance strategies are of special interest. An important segment of the maintenance manage- ment system is maintenance planning. One of the major problems is uncertainty of events which signicantly aect maintenance planning. These events are random by its nature. In particular, the planning of maintenance is analyzed in the case when the set of activities has a hierarchical structure and duration, of each activity from a given set of activities, is random value. Assuming that the activity at a higher level of hierarchy can not begin before the completion of all activities at a lower level of hierarchy, and that losses incurred in the case of delayed activities, i.e., losses incurred in the case of premature activity are known, it is necessary to establish optimal activating strategy for each activity from given set of activities. In the case of one level hierarchy, problem is reduced to the well known newsboy problem, but it is too complicated in general. In this study, a heuristic approach is proposed for the solution of general problem that is based on iterative application of the solution of a simple two levels hierarchy problem. Aircrafts are modern high-tech means of transport with a large number of components and complex structure. Components of aircraft are used in dierent ways, they suer dierent loads and are maintained by the programs that are best suited for them. One way to overcome this complexity is so-called hierarchical decomposition. Complex concept at one level of abstraction is seen as unied. At the lower level of abstraction it is seen as a concept that consists of parts (other components). Repeated application of described procedure gives the so-called hierarchical bill of material. So one of the important concepts in the aircraft maintenance systems is bill of material. A particular problem is to provide quality hierarchical data structures to the aircraft maintenance management system, i.e., to provide quality bill of material. This study proposes a exible structure of the bill of material which greatly supports disseminate its content..

Analysis of anatomical and morphological characteristics of the nasal pyramid as a criterion for approach selection in rhinoplasty.

Rinoplastika je sigurno jedan od najvećih izazova za hirurga u domenu estetske hirurgije. Nos sa svojim centralnim položajem na licu ima iznimno važnu ulogu u interpersonalnoj rekogniciji tako da se ne dopušta ni minimalna greška u njegovoj remodelaciji, posebno sa aspekta uvek prisutnih visokih očekivanja pacijenata. U rinoplastici se najčesće koriste dva klasična operativna pristupa, zatvoreni i otvoreni pristup. Indikacija za odabir pristupa u rinoplastici ne sme biti bazirana na kriterijumu koji proizilazi iz subjektivnog afiniteta hirurga, već na preciznu preoperativnu evaluaciju anatomskih, morfoloških i topografskih karakteristika deformiteta nazalne piramide, odnosno na što objektivniji kriterijum. Kao klasične indikacije za otvoreni pristup, navode se značajna iskrivljenost nosa, iskrivljen i u isto vreme sedlast nos, asimetrja nosa uključujući i posledice rascepa usne i/ili nepca, kao i u 2/3 slučajeva sekundarna rinoplastika, dok se sve ostale rinoplastike rade zatvorenim pristupom. Iz dostupne savremene stručne literature, jasno se da uočiti da izbor pristupa odnosno indikacije za otvoreni i zatvoreni pristup nisu dovoljno uniformne i utemeljene na objektivnim kriterijumima, iz tih razloga je preduzeto ovo istraživanje. Cilj ovog istraživanja je da se ispita postojeći veliki broj standardizovanih morfo-anatomskih parametra koji karakterišu lice i nosnu piramidu, uključujući i novo otkrivene tačku kyphion i dorzoprofilni ugao, kako bi se načinila selekcija onih koji svojim realnim i objektivnim značajem, kao i sa svojom jednostavnom uočljivosti i praktičnom mogućnošću beleženja i mogli biti inkorporirani u smernice, odnosno indikacije za odabir pristupa u rinoplastici, kao i kriterijuma za procenu uspešnosti izvedene rinoplastike. Studija je planirana po tipu morfo-anatomske, kadaverične i klinicke. Bitne morfo-anatomske karakteristike nosne piramide za koje ne postoje standardni kriterijumi ili su oni nedovoljno definisani, utvrđene su na seriji od 44 kadaverična preparata, metodama antropometrije i radiološke analize...Rhinoplasty is certainly one of the biggest challenges for surgeons in the field of aesthetic surgery. The nose with its central position on the face has an extremely important role in interpersonal recognition, so that it does not allow even the minimum error in its remodeling especially in terms of ever-present high expectations of patients. In rhinoplasty are frequently used two classical operational approaches, external and internal approach. Indications for approach selection in rhinoplasty should not be based on criteria arising from subjective surgeons’ affinity but on precise preoperative evaluation of anatomical, morphological and topographical characteristics of the nasal pyramid deformity, on an objective criterion as well. As the classical indications for open access, according to a significant distortion of the nose, twisted at the same time saddled nose, nasal asymmetry including the consequences of the cleft lip and / or palate as well as 2/3 of a secondary rhinoplasties, while all other for closed rhinoplasty approach. From the available modern scientific literature, it is clear to note that the choice of approach or indications for internal and external approach, are not uniform and based on objective criteria for these reasons, this study was undertaken. The aim of this study is to examine the existing large number of standardized morpho-anatomical parameters that characterize the face and the nasal pyramid, including a newly discovered spot kyphion and dorsal profile angle, to the selection of those who made her real and objective character, as well as with its simple visibility and convenience of recording and could be incorporated into the guidelines and indications for the choice of approach in rhinoplasty, as well as the criteria for assessing the performed rhinoplasty. The study was planned by type of morpho-anatomical, cadaveric and clinical. Important morpho-anatomical characteristics of the nasal pyramid for which there are no standard criteria, or they are not wll-defined, have been established on a series of 44 cadaveric preparations, anthropometry methods and radiological analysis. A clinical study was retrospective, partly prospective and controlled..

Electronics ceramics grain boundaries and complex fractal dimension

Analysis of ceramic grain boundaries, esspecially for BaTiO3 , is also important for its dielectric and conductive properties. In this regard, the fractal analysis was highlighted. The grain contacts geometry based on intergranular contact surface fractal morphology was the subject of our long term research. A new approach based on complex dimension fractal geometry and correlation between microstructurenanostructure and rare-earth properties and other additives doped BaTiO3-ceramics and electronics properties, is applied . In addition to the continuous type of scaling typical for real standard fractal objects, complex objects are considered here, which also have a discrete scaling symmetry with logarithmic space period. That rely on their appearance on the various , micro and macro, electrical and other properties of BaTiO3-ceramics

Fractal nature Heywang model correction and Brownian motions

Ceramics grains contacts are essential for understanding complex dielectric properties of electronic ceramics materials. Since the actual contact surface is an irregular object, the theory of fractal sets is applied. Also, the Heywang model of intergranular capacity are introduced as a basic idea for relations with fractal structure. The BaTiO3-ceramics has fractal form in, at least, two levels: shapes and distributions of grains and intergranular contacts. Using fractal modeling approach, reconstruction of microstructure, like shapes of grains or intergranular contacts can be successfully done. Furthermore, the area of grains surface is calculated by using fractal correction that expresses the irregularity of grains surface through fractal dimension. It is known that BaTiO3 and similar ceramics have fractal nature based on three different phenomena. First, there is process of Brownian-fractal motions inside the material during sintering in the form of flowing micro-particles –ions, atoms, electrons which is an essentially fractal phenomena. This motion has fractal structure and can be undergo the process of fractal modification. Second, there are so called “negative space” made of pores and intergranular space. Being extremely complex, the pore space plays an important role in microelectronic, PTC and other phenomena. Third, ceramic grains have fractal shape seeing as a contour in cross section or as grain’s surface. These triple factors, in combination, make the microelectronic environment of very peculiar electro-static and dynamics microelectronic environment. In order to obtain an equivalent circuit model, which provides a more realistic representation of the electronic materials electrical properties, in this article an intergranular contacts model for the BaTiO3 electrical properties characterization were determined and implemented. Considering obtained results, the directions of possible BaTiO3-ceramics materials properties prognosis are determined according to the correlations synthesisstructure- properties

The Rare earth Neodymium Zinc Titanite properties in microwave telecommunications and fractal nature structure analysis

In this paper we present the research results on dielectric properties based on Rare earth Neodymium Zinc Titanites (NZT). These results show that we have a stable perovskite structure and the other structure search suggest that the monoclinic crystal structure could be proposed for NZT. Modelling and simulation were used in this research to define the atomic position and crystal structure of NZT. The compositions have very specific dielectric properties which could useful in microwave telecommunications. It is very important to reduce the size, weight and microelectronic devices coast for future applications. So, the new miniaturization, better packaging and higher level of integrations, by using multi-layer processes and advanced interconnection methods are very important for modern telecommunications. In that sense, some new results and knowledges about fractal nature in materials, electronic ceramics and perovskites are very important for new fractal microelectronics applications for modern communications and IT technologies. Instead of classic semiconductor technologies, which are not anymore so much perspective and promising in this area. Finally, all of these aspects are very important for microanthena systems in telecommunications

Structural and Dielectric Properties of Rare earth Neodymium Zinc Titanite

Using the high -resolution x-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), and temperature-dependent microwave resonator characterization the dielectric properties and phase assemblage of Rare earth Neodymium Zinc Titanite (NZT) was investigated in this research work. NZT ceramics samples were prepared via mixed oxide. The result shows that it is distrustful to be a stable perovskite structure, in fact something comparable to Ilmenite structure, nevertheless further research shows that the monoclinic structure can be purposed for NZT. The Modelling and simulation were used in this study to define the atomic position and structure of NZT. In conclusions, single-phase ceramics of NZT; have been synthesised at every sintering temperature 1250-1675°C. NZT has the temperature coefficient of resonant frequency 47 MK-1, Quality factor was 42000 at frequency of 4.33 GHz and relative permittivity 36. The crystal structure of NZT is monoclinic with Bravais Lattice P and space group of P21/n. Kikuchi line shows that this material has a single phase. These compositions have promising dielectric properties and can be used in microwave telecommunications

Forensic Science and Fractal Nature Analysis

The forensic photography, also referred to as crime scene photography, is an activity that records the initial appearance of the crime scene and physical evidence, in order to provide a permanent record for the court. Now a day, we can imagine the crime scene investigation without photography evidence. Crime or accident scene photographs can often be re-analysed in cold cases or when the images need to be enlarged to show critical details. Fractals are rough or fragmented geometric shape that can be subdivided in parts, each of which is a reduced copy of the whole Fractal dimension (FD) is an important fractal geometry feature. There are many applications in various fields including image processing, image analysis, texture segmentation, shape classification and identifying the image features such as roughness and smoothness of an image. The damage image can be reviewed, analyzed and reconstructed by fractals

Fractional Calculus Model of Electrical Impedance Applied to Human Skin

Fractional calculus is a mathematical approach dealing with derivatives and integrals of arbitrary and complex orders. Therefore, it adds a new dimension to understand and describe basic nature and behavior of complex systems in an improved way. Here we use the fractional calculus for modeling electrical properties of biological systems. We derived a new class of generalized models for electrical impedance and applied them to human skin by experimental data fitting. The primary model introduces new generalizations of: 1) Weyl fractional derivative operator, 2) Cole equation, and 3) Constant Phase Element (CPE). These generalizations were described by the novel equation which presented parameter (beta) related to remnant memory and corrected four essential parameters (R-0, R-infinity, alpha, tau(alpha)). We further generalized single generalized element by introducing specific partial sum of Maclaurin series determined by parameters (beta(*), gamma,delta ...). We defined individual primary model elements and their serial combination models by the appropriate equations and electrical schemes. Cole equation is a special case of our generalized class of models for beta* = gamma = delta = ... = 0. Previous bioimpedance data analyses of living systems using basic Cole and serial Cole models show significant imprecisions. Our new class of models considerably improves the quality of fitting, evaluated by mean square errors, for bioimpedance data obtained from human skin. Our models with new parameters presented in specific partial sum of Maclaurin series also extend representation, understanding and description of complex systems electrical properties in terms of remnant memory effects

Generalized Lorentz model description of electrical, dielectric, conductive and magnetic processes two-time relaxations in BaTiO3 ceramics with constitutive relations

In this study, generalized Lorentz model is considered in the framework of dielectric, conductive and/or magnetic responses of materials. Beside positive temperature coefficient of resistivity (PTCR) materials (current stabilizers, time delay circuits and current limiters for overvoltage or overcurrent protection, temperature sensors, self-heating, …), magnetic properties indicate to multifunctional or specific applications (for example, nanocubic technologies). AC conductivity studies of various BaTiO3 ceramics or similar ceramics produced equivalent circuits with impedance spectra, usually within the framework of RCPE elements serial connection (CPE - constant phase element) or Cole element. One of the first models that explains PTC effect is the Heywang model, in terms of grain boundaries potential barriers of the Shottky type. Dielectric frequency spectra can be described in similar relationships. However, magnetic features of BaTiO3 ceramics are not well described. In this presentation all three behaviors (dielectric, conductive and magnetic) of materials and their relationships are considered in the case of electric or magnetic alternate fields, which are the basis for experimental measurements