Open Source Software for Train Control Applications and its Architectural Implications

This document describes the research results that were obtained from the development of safety-critical software under the principles of open source. Different model-based designs and architectures within the railway control system application domain, including re-usable formalisms for verification \&{} validation, were investigated. The reduction of possible security threats caused by platform or supplier specific adaptations of modelled open-core software was analysed, and a possible solution by the usage of hardware virtualisation, instead of traditional memory management, was elaborated. At core of this work, the development of a graphical domain-specific language for modelling parts of the European Train Control System (ETCS) is presented, which is based on specialised data, control flow formalisms, and language elements derived from the specification document. For a more precise and therefore more appropriate syntax definition for safety-critical systems, the already existing GOPRR meta meta model was extended to the newly developed GOPPRR meta meta model. GOPPRR includes methods for defining constraints by the object constraint language, which supports the definition of static semantics to ensure correct model instances. Parts of the ETCS specification related to the train on-board unit were modelled in a new meta model. To transform the developed model of the ETCS specification into an executable application, a domain framework, according to the new meta model and the corresponding code generator, were designed and implemented, which have implicitly an integrated support for the verification \&{} validation process. To proof the correctness of the modelled specification, the resulting application was executed in a simulative environment to obtain simulation traces. The correspondence of traces to the expected data from the specification document supported the used methods and strategies in this dissertation as proof of concept

The effect of tow grouping resolution on shearing deformation of unidirectional non-crimp fabric

In the rapidly growing large-scale composites industry, specifically in the area of wind turbine blade manufacturing, reducing costs through reduced man-hours and materials while simultaneously increasing quality has become a major focus. One strategy is to automate the manual lay-up process. Automation techniques used in the aerospace industry are too costly for wind turbine blade manufacturing; therefore, new techniques need to be investigated. This research describes a new fabric pre-shearing process to reduce out-of-plane deformations during the lay-up process that enables automated deposition of unidirectional non-crimp fabrics (NCF) in molds. This new process controls the manipulation of broad-loom NCF fabrics such that fabric geometry is well controlled, reducing the need for naïve and inconsistent manual lay-ups. Previous research modeled the behavior of NCF fabric in order to predict the final characteristics of the fabric after shearing. However, this model was never validated with NCF fabric. The goal of this research was to determine the effects of shearing process parameters on NCF fabric geometry and validate the predicted characteristics generated by the previous shearing model. An empirical study of fabric shearing was conducted and the analysis of fabric samples transformed by the pre-shearing process is presented. A comparison of the conformance of un-sheared fabrics to pre-sheared fabrics shows that fabric pre-shearing reduces out-of-plane deformations and produces consistent fabric geometry

Innovation Campus Newest Piece of NU\u27sTradition of Excellence

Throughout the years, the University of Nebraska (NU) System has transformed and adapted to meet the ever-changing needs of our state. It continues to innovate and adapt to new technologies, ensuring our students receive a quality education while providing top-tier research for the nation. Part of that evolution is the Nebraska Innovation Campus(NIC) that will bring new opportunities to our students and state. I enjoyed touring the new facility this month with Chancellor Harvey Perlman and NIC’s Executive Director Dan Duncan. Still in its first phase of construction, the impressive facility is a research campus designed to facilitate new and more in-depth partnerships between the University and the private sector. NIC is being built on the former Nebraska State Fairgrounds. The first stage of construction includes the renovation of the 4-H building. The building is being repurposed to serve as a multi-functional meeting space, including a 400-seatauditorium, a 400-seat banquet room and several smaller rooms for breakout sessions, but the architecture and features of this iconic building – both inside and out – still stand strong.While the building’s original purpose has changed, its new occupants will protect and preserve this great cultural landmark for many years to come. As I was visiting the facility, NICofficials were also preparing to move into their new, state-of-the-art office space nearby. In addition to the conference center, the campus will eventually be home to a wet lab, a food processing pilot plant and a greenhouse complex. A number of private companies are in conversations with NIC about partnerships. Con Agra will move in next year, beginning the public-private partnerships. The campus will also include a business accelerator to help small business owners expand their operations. The partnerships are intended to pursue the mission of providing a “dynamic environment where university and private sector talent transform ideas into innovation that impacts the world.

Innovation Campus Newest Piece of NU\u27sTradition of Excellence

Throughout the years, the University of Nebraska (NU) System has transformed and adapted to meet the ever-changing needs of our state. It continues to innovate and adapt to new technologies, ensuring our students receive a quality education while providing top-tier research for the nation. Part of that evolution is the Nebraska Innovation Campus(NIC) that will bring new opportunities to our students and state. I enjoyed touring the new facility this month with Chancellor Harvey Perlman and NIC’s Executive Director Dan Duncan. Still in its first phase of construction, the impressive facility is a research campus designed to facilitate new and more in-depth partnerships between the University and the private sector. NIC is being built on the former Nebraska State Fairgrounds. The first stage of construction includes the renovation of the 4-H building. The building is being repurposed to serve as a multi-functional meeting space, including a 400-seatauditorium, a 400-seat banquet room and several smaller rooms for breakout sessions, but the architecture and features of this iconic building – both inside and out – still stand strong.While the building’s original purpose has changed, its new occupants will protect and preserve this great cultural landmark for many years to come. As I was visiting the facility, NICofficials were also preparing to move into their new, state-of-the-art office space nearby. In addition to the conference center, the campus will eventually be home to a wet lab, a food processing pilot plant and a greenhouse complex. A number of private companies are in conversations with NIC about partnerships. Con Agra will move in next year, beginning the public-private partnerships. The campus will also include a business accelerator to help small business owners expand their operations. The partnerships are intended to pursue the mission of providing a “dynamic environment where university and private sector talent transform ideas into innovation that impacts the world.

A Study of Indentation Cracking in Brittle Materials Using Cohesive Zone Finite Elements

Cohesive zone finite element simulations of pyramidal indentation cracking in brittle materials have been carried out in order to: (1) critically examine indentation cracking models that relate fracture toughness to indentation data; (2) determine the underlying physical mechanisms of indentation crack growth from a continuum view and their relationship to material properties; (3) explore the influence of indenter geometry on crack extension; and (4) provide a platform from which future simulations can add more complex material behavior as well as guidance for experimental measurements of fracture toughness. Standard fracture toughness geometries in addition to simplified indentation geometries were simulated in order to assess the advantages and limitations of using cohesive zone finite element simulations to study indentation cracking in brittle materials. Simulation results were found to be consistent with linear-elastic fracture mechanics when crack lengths approximately 10 times larger than process zone sizes. Results from Vickers indentation cracking simulations showed deviations from standard models and additional material dependencies not considered in therein. A transition in cracking behavior from median type cracks to Palmqvist type cracks was observed as the ratio of elastic modulus to hardness increased and plasticity played a more prominent role in the deformation response. Separate stress intensity factor solutions were derived for the two cracking regimes by applying simple scaling relationships and observations from the finite elements. Simulations of different indenter geometries were found to correlate well with the stress intensity factors. In addition, the indentation cracking response could be tailored to a specific behavior by changing the indenter centerline-to-face angle. Cohesive zone finite element simulations were found to be well suited to exploring, improving, and studying the materials science of indentation cracking