Numerical Studies of Dark Energy Models and Observations

The cosmological standard view is based on the assumptions of homogeneity, isotropy and general relativistic gravitational interaction. These alone are not sufficient for describing the current cosmological observations of accelerated expansion of space. Although general relativity is extremely accurately tested to describe the local gravitational phenomena, there is a strong demand for modifying either the energy content of the universe or the gravitational interaction itself to account for the accelerated expansion. By adding a non-luminous matter component and a constant energy component with negative pressure, the observations can be explained with general relativity. Gravitation, cosmological models and their observational phenomenology are discussed in this thesis. Several classes of dark energy models that are motivated by theories outside the standard formulation of physics were studied with emphasis on the observational interpretation. All the cosmological models that seek to explain the cosmological observations, must also conform to the local phenomena. This poses stringent conditions for the physically viable cosmological models. Predictions from a supergravity quintessence model was compared to Supernova 1a data and several metric gravity models were studied with local experimental results. Polytropic stellar configurations of solar, white dwarf and neutron stars were numerically studied with modified gravity models. The main interest was to study the spacetime around the stars. The results shed light on the viability of the studied cosmological models.Siirretty Doriast

Automated hardening and testing CentOS linux 7 : security profiling with the USGCB baseline

Operating system hardening for a Linux operating system can be automated and needs to be performed in high security environments. Automated hardening is needed in virtual environments with lots of instances. Also, for identical system environments deployment automation is essential. Automatic system hardening is a well-established administration procedure. The purpose of this work was to combine several tools and guides in one text and to obtain a low-level guide for a secure virtual environment. In this Bachelor's Thesis work, theory of Linux operating system hardening was studied and a study on automated installation of hardened Linux operating systems, according to the USGCB security standard, was performed. Also, the security standard, SCAP content via XCCDF checklist was studied and a new independent rule was created for system hardening. The produced environment consists of a hardened virtualization host and three hardened guest virtual machines. The system environment was designed in parts with VMware Workstation and implemented on DELL server hardware, where the study and analysis of the automated hardening were performed. A quantitative results of the hardening are discussed and the created and tested checklists presented. The results indicate that a sufficiently good security state can be obtained with the used tools and with only a little manual configuration.Linux -käyttöjärjestelmäkoventaminen, eli tietoturvakäytännön mukainen konfigurointi, voidaan automatisoida CentOS käyttöjärjestelmälle. Kovennettu käyttöjärjestelmä on yleinen vaatimus korkean turvallisuuden ympäristöissä. Automatisoidusti suoritettu kovennus on tarpeen esimerkiksi virtuaaliympäristöissä missä on paljon virtuaalikoneita, tai jos tietyllä tavalla kovennettu virtuaalikone täytyy asentaa useaan eri paikkaan. Automaattinen käyttöjärjestelmäkoventaminen on tietoturva-ammattilaisten hyvin tuntema toimenpide. Tämän työn tarkoituksena on, uuden kovennustavan keksimisen sijaan, tutkia ja tuottaa dokumentti usean vapaan lähdekoodin kovennusohjelmiston käytöstä kovennetun virtuaaliympäristön tuottamisesta. Tässä työssä on tutustuttu käyttöjärjestelmäkoventamisen teoriaan ja tutkittu automatisoitua USGCB tietoturvastandardin mukaista Linux -käyttöjärjestelmäkoventamista. Tässä työssä on myös tutkittu tietoturvastandardi SCAP:in mukaisen itsenäisen kovennussännön tuottamista. Tuotettu ympäristö koostuu kovennetusta virtuaalialustasta sekä kolmesta virtuaalikoneesta. Virtuaalikoneet on rakennettu sekä testattu VMware Workstation -virtuaalikonneessa ja varsinaista tutkimusta varten asennettu DELL PowerEdge palvelimelle. Tutkimuksen tuloksena esitetään analyysi käytetyn OpenSCAP ohjelmiston tulosten perusteella. Analyysin perusteella esitetään CentOS käyttöjärjestelmän automaattisen koventamisen tuottavan riittävän hyvän tietoturvatason. Prosessi vaati vähäistä manuaalista konfigurointia asennuksen jälkeen

Floating platforms: Encounters between performance art and science

Peer reviewe