An important consideration for the successful design of flexible pavement systems in Texas is the prediction and control of the vertical change in height of the subgrade soils due to swelling upon wetting and shrinkage upon drying. The purpose of this study was two-fold. The first objective was to measure the volume change characteristics of clayey subgrade soils from the SH130 corridor in Texas through a suction based approach using the pressure plate. The second goal was to test the effects of treating the soils with the EcSS-3000 chemical stabilizer and lime on controlling the vertical movement and moisture susceptibility. Recent research studies have indicated that the suction compression index, γh, is the parameter that has the most significant direct influence on the amount of vertical movement taking place in expansive soils. The results indicate a 40-50 % reduction in the average γh values and a similar magnitude of reduction in combined swell and shrink potential. Further, the resilient modulus (Mr) of representative samples was compared prior to and after treatment separately with 6% hydrated lime and EcSS-3000. The purpose of measuring the Mr of the soils was to analyze the moisture susceptibility of the soils and to study the effects of subgrade stabilization on performance of typical pavement systems against the common distresses using the ME-PDG software tool. Also, the contribution of the expansive soils to pavement roughness was measured in terms of loss of serviceability (ΔPSI) using the measured Mr and vertical movement values. The analysis indicate a significant reduction in drop of Mr values of the lime and EcSS-3000 treated soils and a marked improvement in cracking and subgrade rutting characteristics of the pavements. An average reduction in ΔPSI of the pavements by 0.2 to 0.3 points was observed on the stabilized soils. This study on expansive subgrades and the associated effects of ionic stabilization have yielded the information necessary as guidance for dealing with relevant engineering problems due to expansive soils.

Developing software for high-dependable space applications and systems is a formidable task. With new political and market pressures on the space industry to deliver more software at a lower cost, optimization of their methods and standards need to be investigated. The industry has to follow standards that strictly sets quality goals and prescribes engineering processes and methods to fulfill them. The overall goal of this study is to evaluate if current use of ECSS standards is cost efficient and if there are ways to make the process leaner while still maintaining the quality and to analyze if their V&V activities can be optimized. This paper presents results from two industrial case studies of companies in the European space industry that are following ECSS standards and have various V&V activities. The case studies reported here focused on how the ECSS standards were used by the companies and how that affected their processes and how their V&V activities can be optimized. / Utveckling av programvara för hög funktionssäkra rymden applikationer och system är en formidabel uppgift. Med nya politiska och marknadsmässiga trycket på rymdindustrin att leverera mer mjukvara till en lägre kostnad, optimering av deras metoder och standarder måste utredas. Industrin har att följa standarder som absolut uppsättningar kvalitetsmål och föreskriver tekniska processer och metoder för att uppfylla dem. Det övergripande målet för denna studie är att utvärdera om den nuvarande användningen av ECSS standarder är kostnaden effektivt och om det finns sätt att göra processen smidigare och samtidigt bibehålla kvaliteten och för att analysera om V & V verksamhet kan optimeras. Detta dokument presenterar resultat från två industriella fallstudier av företag inom den europeiska rymdindustrin som är Följande ECSS krav och ha olika V & V verksamhet. Fallstudierna redovisas här fokuserat på hur ECSS standarder som används av företag och hur detta påverkat deras processer och hur deras V & V verksamhet kan optimeras.

The introduction of standards in software development is more or less common practice today and regarding software for space applications, standards are one of the primary mechanisms to ensure a sufficient quality level. The space industry has special requirements in terms of reliability and dependability and the European Cooperation for Space Standardization (ECSS) standards is a tool used to fulfill them. The use of standards provides many benefits however it also comes with a compliance cost, in terms of, for example, additional documentation and activities. For making the right decisions on which development and quality assurance activities to focus on, it is important to know not only their added value but also their costs. In this paper a method is presented for a Cost of Standard Compliance Analysis (CoSCA) in software development. It consists of seven steps and is based on a model which divides the costs into four different types based on the actual reason for conducting activities required by the standard. The four different types of compliance cost are quality-adding, confidence-adding, adherence and development necessary costs. The adherence costs are those costs that are required by or follow from the use of a standard but do not add any immediate value to the functionality, quality or quality assurance of the software. As a result of a CoSCA analysis, the cost for complying with the standard for all the separate development activities is calculated. Initial results from applying the method to a company, that develops software for the space industry and complying with the ECSS standards, are presented. The result gives an indication of potential optimization possibilities and for the top ten adherence activities examples are presented. The evaluation showed that the method is practical and usable with an acceptable level of effort and that it helps pinpoint development activities with high adherence costs.

Space industry has been booming in the recent times, investments have not justbeen made on satellites and launch vehicles but also on space sustainability. Spaceindustry has its users in national agencies, private commercial agencies, academia andexperimental organisations. Smallsats and cubesats are one of the most interestingdomains in space industry today. This has led to pure research and astonishinginnovations in this domain to enable lower costs, lower mass, increased orbital period,better accessibility and global impact. Development of sustainable products requiresthe system to qualify a certain standard set up in the industry. This standard ensuresthat the system safely completes its mission up in space. The problem described byGomSpace Sweden concerns one of their ongoing products, a cold gas propulsionunit which is suitable for a typical 6U cubesat called ESA6DOF. In large, the productconsists of a structure, two propellant tanks, one plenum tank, piping, electronics andsix thrusters. Qualification of this propulsion system module involves the system toundergo a random vibration test according to ECSS standards. This thesis work shallbe focused on setting up the structure needed to perform random vibration simulationsin COMSOL. This step is done to primarily iterate the design to make it robust enoughto sustain loads during flight and also to avoid any physical damages during testingcampaign. Followed by performing the actual random vibration test at a facility usingthe assembled ESA6DOF propulsion module. Finally, this ends with validating thesimulation results with that of testing. / Rymdindustrin har blomstrat den senaste tiden. Investeringar har inte bara gjortspå satelliter och bärraketer utan också på hållbarhet i rymden. Rymdindustrinhar sina användare i nationella organisationer, privata kommersiella organisationer,universitetsvärlden och forsknings organisationer. Smallsats och cubesats är tvåav de mest intressanta domänerna inom rymdindustrin idag. Detta har letttill grundforskning och häpnadsväckande innovationer inom detta område för attmöjliggöra lägre kostnader, lägre massa, ökad omloppstid, bättre tillgänglighetoch global påverkan. Utveckling av hållbara produkter kräver att systemet möteren viss standard uppsatt i branschen. Denna standard säkerställer att systemetsäkert slutför sitt uppdrag uppe i rymden. Problemet som beskrivs av GomSpaceSweden gäller en av deras pågående produkter, en kallgasdrivenhet lämplig för entypisk 6U cubesat kallad ESA6DOF. I stort består produkten av en struktur, tvådrivmedelstankar, en plenumtank, rörledningar, elektronik och sex finjusterarraketer.Kvalificeringen av denna framdrivningssystemmodul innebär att systemet genomgåren slumpmässig vibration enligt ECSS-standarder. Detta examensarbete harfokuserat på att sätta upp den struktur som behövs för att utföra slumpmässigavibrationssimuleringar i COMSOL. Detta steg gjordes för att i första hand itereradesignen för att göra den robust nog att tåla belastningar under flygning och ävenför att undvika fysiska skador under testkampanjen. Efter detta utfördes det faktiskaslumpmässiga vibrationstestet på en anläggning med den sammansatta ESA6DOF-framdrivningsmodulen. Avslutningsvis utfördes validering av simuleringsresultatenmot testresultaten.

The Concurrent Design Platform 4 (CDP4®) is a collaborative Model-Based Systems Engineering (MBSE) software tool conceived for architecting complex systems. Nevertheless, there are limitations concerning the manageable number of system options. The upcoming Siemens tool for generative engineering, Simcenter™ Studio, is attempting to overcome this limitation by enabling automatic synthesis and evaluation of architecture variants. The motivation for the Generative Concurrent Design (GCD) project as a collaboration between RHEA, Siemens and OHB is to develop a combined prototype of these two tools. This thesis presents a modelling of Copernicus Next Generation (CNG) space component, using generative capabilities in a typical Phase-0 study. It represents the third step of the bottom-up GCD validation process, intended to investigate how architecting differs among “Sub-system”, “Systems” and “Systems of Systems (SoS)”. Therefore, this work provides an architecting strategy which is generalizable for other SoS use-cases and contributes to assess whether extensions to ECSS-E-TM-10-25 are necessary to successfully support GCD. / Concurrent Design Platform 4 (CDP4®) är ett samarbetsverktyg för modellbaserad systemteknik (MBSE) som utformats för att bygga komplexa system. Dock finns det begränsningar vad gäller det antalet hanterbara systemalternativ. Det kommande Siemens-verktyget för generativ teknik, Simcenter™ Studio, försöker övervinna denna begränsning genom att möjliggöra automatisk syntes och utvärdering av arkitekturvarianter. Motivationen för Generative Concurrent Design (GCD) -projektet som ett samarbete mellan RHEA, Siemens och OHB är att utveckla en kombinerad prototyp av verktygen CDP4® och Simcenter™. Detta examensarbete presenterar en modellering av rymdkomponenten Copernicus Next Generation (CNG) med användning av generativa funktioner i en typisk fas-0-studie. Den representerar det tredje steget i GCD-valideringsprocessen nedifrån och upp, avsedd att undersöka hur arkitekturen skiljer sig åt mellan "Sub-system", "Systems" och "Systems of Systems (SoS)". Detta arbete ger därför en arkitektonisk strategi som är generaliserbar för andra SoS-användningsfall och bidrar till att bedöma om förlängningar till ECSS-E-TM-10-25 är nödvändiga för att framgångsrikt stödja GCD.