Magistro tezių tikslas yra sukurti skirtingų programinės įrangos tipų (gatavos arba reikalingos sukurti) įsigijimo valdymo gaires. Tokioms gairėms sukurti pirmiausia reikia apibrėžti programinės įrangos tipus. Kiekvienam apibrėžtam programinės įrangos tipui nustatyti jų įsigijimo keliai ir sudaryti kriterijai, kurie padėtų parinkti tinkamą įsigijimo kelią. Literatūros šaltinių apžvalgoje išanalizavus programinės įrangos įsigijimo modelius bei standartus nustatyti šie programinės įrangos tipai: COTS, MOTS ir naujai kuriama programinė įranga (NKPĮ). Remiantis įsigijamos programinės įrangos tipais ir projekto charakteristikomis nustatyti įsigijimo keliai. Programinės įrangos įsigijimo keliui parinkti sudaryti kriterijai, kurie apibūdina įsigyjamą programinę įrangą, įsigijimo projekto resursus ir aplinkos faktorius. Veiklos, kurios turi būti vykdomos kiekviename programinės įrangos įsigijimo kelyje, nustatytos panaudojant CMMI-ACQ procesų modelį. Procesų veiklos vykdytinos kiekviename programinės įrangos įsigijimo kelyje: nurodoma, kokiu keliu turi būti įsigyjama programinė įranga, kokias veiklas reikia vykdyti, pateikiamos rekomenduojamos pastangos, reikalingos kiekvienam PĮ įsigijimo keliui. / The primary objective of master thesis is to provide guidelines for managing a different types of software acquisition projects. Firstly, to provide guidelines is necessary to define types of software. Secondly, to create the ways of acquisition for each defined type of software and to create criteria that allows to select the right way of acquisition. During the analysis of existing software acquisition process models software types was defined: COTS (Commercial-off-the-shelf software), MOTS (Modified-off-the-shelf software), fully developed software. To have an effective acquisition processes, it is useful to employ an adequate level of formality for those processes according to the characteristics of the acquisition project. The ways of software acquisition was defined in accordance with defined software types and characteristics of acquisition projects. That can be used as a guideline on what level of formality is appropriate for the actual software acquisition project. To select the way to acquire software, there were created criteria that describes the characteristics of acquiring software, acquisition project resources and environment factors. CMMI-ACQ process model was used to define activities of each software acquisition way. Each acquisition way contains suggestions on what activities to perform for the different acquisition project customization.

The cooling systems in a gas turbine are especially important as the turbine blades and vanes are exposed to extreme temperatures. The relatively cool air is extracted from the compressors and fed to the turbines to cool the turbine blades. The manufacturing of these blades and channels used to cool is especially complicated using conventional manufacturing techniques. Additive Manufacturing (AM) gives the designer much more freedom to design core components. The AM technique currently explored is the Selective Laser Melting process (SLM). The surface area is exposed to the cooling airflow by using lattice structures which can be manufactured at relative ease using AM. This thesis will provide some insights into using AM parts for the cooling, by analyzing the pressure drop that could be expected from superalloys that are manufactured using AM. The surface roughness is an inherent property of the AM components therefore it would be interesting to analyze a turbulent flow through AM channels (CM247LC and INCONEL 939). The thesis deals with turbulent flows as the airflow used for cooling in the gas turbine is most likely turbulent.  The friction factor (Darcy–Weisbach friction factor) is used to relate the impact of the surface roughness to the pressure drop. The results from the previous experiments are contrasted as the flow in the previous experiments was assumed to be fully developed but in reality, it was not. And the accuracy of the previous results to the actual fully developed flow will shed some light on the feasibility of the flow analysis techniques used in the previous experiments. It is found that the previous experimental results for the CM247LC TPs have good agreement with current experimental results but INCONEL 939 exhibits significant deviation. The possible reasons for the deviations are directly linked to the assumptions made to calculate the minor losses. The Test Pieces (TP) analyzed in this thesis have varying length to diameter (L/D) ratios and the impact of the variation of different L/D ratios is analyzed along with varying pressure ratios. Where the flow resistance increases with an increase in L/D and pressure ratio. The technique to accommodate the compressibility of the airflow is also explored in this thesis. Finally, reasons for the manifestation of anomalies are discussed. The probability of the compressibility effects of the airflow on the anomalies was found to be quite high, and concluding remarks are provided.

In this thesis I investigate characteristics of turbulent flow in a channel where one of the walls has riblets, superhydrophobic microribs, or a hybrid surface with traditional riblets built on a superhydrophobic microrib surface. PIV measurements are used to find the velocity profile, the turbulent statistics, and shear stress profile in the rectangular channel with one wall having a structured test surface. Both riblets and superhydrophobic surfaces can each provide a reduction in the wall shear stress in a turbulent channel flow. Characterizing the features of the flow using particle image velocimetry (PIV) is the focus of this research. Superhydrophobicity results from the combination of a hydrophobic coating applied to a surface with microrib structures, resulting in a very low surface energy, such that the fluid does not penetrate in between the structures. The micro-rib structures are aligned in the streamwise flow direction. The riblets are larger than the micro-rib structure by an order of magnitude and protrude into the flow. All the test surfaces were produced on silicon wafers using photolithographic techniques. Pressure in the channel is maintained below the Laplace pressure for all testing, creating sustainable air pockets between the microribs. Velocity profiles, turbulent statistics, shear stress profiles, and friction factors are presented. Measurements were acquired for Reynolds numbers ranging from 4.5x10^3 to 2.0x10^4. Modest drag reductions were observed for the riblet surfaces. Substantial drag increase occurred over the superhydrophobic surfaces. The hybrid surfaces showed the greatest drag reduction. Turbulence production was strongly reduced during riblet and hybrid tests.

Une analyse critique de la modélisation des échanges thermiques des câbles d’énergie en galerie est réalisée, avec l’étude de facteurs d’influences propres aux modes de pose des câbles dans ces ouvrages. Les câbles, de plusieurs kilomètres, chauffent du fait du courant transmis dans leurs âmes. Ils sont alors refroidis par une convection forcée turbulente, dans l’axe des câbles, et échangent par rayonnement avec les parois. Pour étudier ce refroidissement, un banc d’essais expérimental a été conçu, en similitude de Reynolds, modélisant différents câbles soumis à un écoulement turbulent développé. Les résultats sont comparés et étayés par des simulations numériques 3D, développées sous l’outil OpenFOAM. Les études réalisées ont permis de mettre en évidence la mésestimation importante de l’échange convectif par la norme existante. Celle-ci propose un refroidissement qui se compose en réalité pour un tiers de l’effet de supports maintenant les câbles et d’un autre tiers d’un écoulement encore en début d’établissement. Le dernier tiers étant le refroidissement effectif des câbles. L’impact des groupements des câbles est aussi étudié, avec un résultat étonnant où un groupe de deux câbles en nappe est trouvé mieux refroidis qu’un seul, lorsque ceux-ci sont placés en proche paroi de la galerie. A l’issue des travaux, une unique loi de refroidissement conservative est proposée, permettant de modéliser tous les cas traités. Cette loi a un impact important sur l’intensité maximale admissible des câbles, qui est dégradée de 5% à 9% par rapport à précédemment pour un cas idéalisé. / A critical analysis of the thermal rating of power cables in tunnels is carried out, with the study of factors of influence specific to cable laying constrains. The heat generation in the cables, due to the transiting current, is dissipated by an axial turbulent forced convection and by radiation with the tunnel walls. To characterize this cooling, an experimental mock-up tunnel has been designed, modelling various cables in a fully-developed turbulent flow. The results are compared and bolstered by 3D numerical simulations, developed under the OpenFOAM code. The studies have highlighted an important underestimation of the convective exchange by the existing standard. Their cooling law is actually a sum of the effects of racks supporting the cables, for a third, and the effect of a flow still underdeveloped for another third. The last third being the actual cooling of the cables. The impact of groups configurations is also studied, with an astonishing result for groups of two cables, which are better cooled than a single cable case, when installed close to a wall. Following the analysis, a single conservative cooling law is proposed to model all studied cases. This law has a significant impact on the permissible current in the cables, which is downgraded from 5% to 9% from previous ratings.