Part I - Level crossings and other level functionals.<br />Part II - Some contributions in statistics of extremes and in statistical mechanics.

An increasing number of people today cross the Beitbridge border of South Africa and Zimbabwe. This comes with a corresponding growth of creative strategies that seek to aid the crossing of those people and goods that may lack the necessary documentation. Such ‘informal’ border crossings have come to define one of the important economic regions in Southern Africa, the post-1994 Limpopo Valley. This thesis approaches routine acts of facilitating undocumented border crossings as an everyday social politics with deep historical roots. By use of archival and ethnographic methods, the thesis examines the social history and embodied practices of a variety of actors who engage in undocumented border crossings. A particular focus is placed on the role of private transporters (omalayitsha), who represent an important link between an exclusionary and yet fragmentary migration regime and undocumented travellers. In three theoretical and four empirical chapters, and inspired by border studies as well as the critical realist approach in migration studies, the thesis connects border practice to irregular movement and cheap labour within a regional context defined, in part, by dispossession. Through thick interpretations of the lived experience of border practice, the study also connects such political economic processes (e.g. migrant irregularity, labour precarity and economic informality) to questions of social identity and migrant subjectivities. By situating the figure of the hyena at the centre of Southern African border struggles, the thesis invents an analytical concept that serves both an empirical and a theoretical task. Empirically, it enables a synthetic understanding of how everyday contestations around the possibility to work across the border for low-skill migrants have been interacting, through time, with broader processes of capital accumulation to partly shape the region’s migrant labour system. Theoretically, it shows how facilitation of undocumented border crossings calls for new sociological models that can account for processes that escape binary classification (as formal or informal, inclusive or exclusive, legal or illegal, ordered or disordered), thus contributing to a better understanding of the role of migration in the contemporary world. / Allt fler människor korsar idag gränsen vid Beitbridge mellan Sydafrika och Zimbabwe. Samtidigt sker en motsvarande ökning av kreativa strategier som gör att även personer och varor som saknar rätt handlingar kan ta sig över gränsen. Dessa ‘informella’ gränsövergångar har kommit att definiera vad som efter 1994 blivit en av de viktigaste ekonomiska regionerna i södra Afrika, Limpopodalen. I denna avhandling betraktas rutinerna vid sådana oregistrerade gränsövergångar som en vardagens politik med djupa historiska rötter. Genom arkivstudier och etnografiska observationer undersöker avhandlingen en samhällshistoria och en mänsklig aktivitet där en rad aktörer är inblandade i en pågående, papperslös migration. En viktig roll i sammanhanget har omalayitsha, dvs. privata transportörer, som ofta är en viktig länk mellan de papperslösa resenärerna och den migrationsregim som å ena sidan stänger dem ute och å andra sidan är så fragmenterad att de tillåts passera igenom. I tre teoretiska och fyra empiriska kapitel, samt med ett angreppssätt hämtat från gränsstudier (border studies) och den kritiskt realistiska skolan inom migrationsstudier, syftar avhandlingen till att förstå gränsövergångens praktik i förhållande till den irreguljära mobilitet och det överskott på billig arbetskraft som sätter sin prägel på en region där många är fattiga och fördrivna. I avhandlingens djuptolkningar av migranternas levda erfarenhet vid gränsen förbinds i sin tur de politiskt-ekonomiska processerna (irreguljär migration, prekära arbetsvillkor och ekonomisk informalitet) med frågor om samhällelig identitet och migrantens subjektivitet. Avhandlingen ser hyenafiguren som central för förståelsen av de ’gränskamper’ (border struggles) som utkämpas i södra Afrika; med hyenan introduceras också ett analytiskt begrepp. Empiriskt sett möjliggör begreppet en syntetisk förståelse av hur vardagliga tvister och problem som präglar arbetsmigrantens försök att jobba på andra sidan gränsen över tid samverkar med större processer av kapitalackumulation, som delvis formar regionens migrantarbetarsystem. I teoretiskt avseende visar begreppet hur förhandlingarna som sker vid gränskontrollen klargör behovet av nya sociologiska modeller som kan redogöra för samhällsprocesser som undflyr varje binär klassificering (som formell eller informell, inkluderande eller exkluderande, legal eller illegal, ordnad eller oordnad), och på så vis bidrar det till en bättre förståelse av migrationens betydelse i dagens värld.

Design for modernization of the railway station Brandys nad Orlici. The reconstruction of both the gridiron. The main rails increase the speed to the maximum, in passing tracks increase the speed to 60 km / h The station will eliminate level crossings on the platform. Width arrangement of the platforms will be designed to accommodate persons with reduced mobility options.

The goal of this thesis was to design the reconstruction of the railway station Svitavy. The line speed was rised from the current value to 160 km·h-1. New platforms were designed, therefore the railway substructure and the drainage were adjusted accordingly. Also, the effective length of the main tracks was extended to 740 m.

The thesis is devoted to analysing of flexible buried arch structures. Modelling of the flexible concrete arch is carried out via a nonlinear finite element model that accounts for soil constitutive relations, soil-structure interactions, sequential construction stages and soil compaction. Advanced FE-model was verified by measurement obtained by full-scale field testing of two buried arches. Mathematical optimization methods of genetic algorithms and Levenberg-Marquardt method are applied to already calibrated complex computational models in order to reduce bending and associated flexural stresses in the concrete section of buried arch. Centre line of the arch is parameterized by cubic Bezier curve to reach interpolation of thrust line. Optimization technique is applied with extensive parametrical study which shows the optimal shapes for buried arches of various span/rise ratios, backfill depths and foundation soil types. For practical application are given coordinates of Bézier curve control polygons of particular resulting shape. Subsequently is applied optimization method for a theoretical reduction of tensile stresses obtained by shape optimization of previously verified numerical model of buried arch. Comparisons of earth pressure, bending moment axial force and deflection of flexible structure during sequential construction of different span/raise ratios of buried arches are presented. The behaviour of flexible buried arch with effect of local traffic load model LM1 has been analysed via 3D finite elements model with respect to different depth of backfill above crown.