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In the time of increased awareness about the environment problems by the public opinion and also intensive international efforts to reduce emissions of greenhouse gases, as well increase of the generation of electrical energy to facilitate industrial growth, the conference offers broad contribution towards achieving the goals of diversification and sustainable development.
Focus of the student conference is to promote the discussion of views from scientists and students from Wroclaw University of Technology, Technical University of Ostrava and Brandenburg University of Technology Cottbus-Senftenberg.
The conference offers prominent academics and industrial practitioners from all over the world the forum for discussion about the future of electrical energy and environmental issues and presents a base for identifying directions for continuation of research.
In the time of increased awareness about the environment problems by the public opinion and also intensive international efforts to reduce emissions of greenhouse gases, as well increase of the generation of electrical energy to facilitate industrial growth, the conference offers broad contribution towards achieving the goals of diversification and sustainable development.
Focus of the student conference is to promote the discussion of views from scientists and students from Wroclaw University of Technology, Technical University of Ostrava and Brandenburg Technical University of Cottbus.
The conference offers prominent academics and industrial practitioners from all over the world the forum for discussion about the future of electrical energy and environmental issues and presents a base for identifying directions for continuation of research.
Based on a longitudinal study of a Pupil Referral Unit (PRU) in England for children excluded from mainstream schools and utilising a moral economy lens, this article explores how solidarity is created and maintained in a very particular community of teachers and learning support assistants (LSAs). A moral economy approach highlights the centrality of people’s moral norms and values for understanding the multi-layered dimensions of solidarity in organisations and how it changes in the context of transformations in the labour process. The article illustrates how teachers and LSAs rely on mutuality, underpinned by moral norms of justice, and values of care, dignity and recognition, to cope with physically and emotionally demanding work that is under-resourced and undervalued. The analysis reveals that solidarity is not only against unjust workplace regimes, but also for connectivity and a humanised labour process.
In the time of increased awareness about the environment problems by the public opinion and also intensive international efforts to reduce emissions of greenhouse gases, as well increase of the generation of electrical energy to facilitate industrial growth, the conference offers broad contribution towards achieving the goals of diversification and sustainable development.
Focus of the student conference is to promote the discussion of views from scientists and students from Wroclaw University of Technology, Technical University of Ostrava and Brandenburg University of Technology Cottbus-Senftenberg.
The conference offers prominent academics and industrial practitioners from all over the world the forum for discussion about the future of electrical energy and environmental issues and presents a base for identifying directions for continuation of research.
As the current literature on public space shows, the significant role of public space in enhancing social sustainability is justified – at least theoretically (Yadollahi, 2015). Nevertheless, in empirical research and practice, a more comprehensive methodological framework is required, which takes into account the complexities of local understandings of public space and social sustainability. This paper is a contribution to the development of such a framework.
The publication addresses architectural conservation as a discipline that plays a vital role in the construction of identities, and therefore, is prone to being appropriated for political purposes. The publication contains 14 research papers that reflect diverse ideologised memorialisation processes and have been grouped by three sub-themes: destruction/reconstruction, transformation, and interpretation. The international contributors from diverse academic backgrounds discuss heritage politics in different cultural regions, nation-states, and political systems in order to investigate cases of ideologised heritage conservation and their relationship to religion, history, and politics.
In recent years, biodiesel is an alternative fuel to petroleum diesel that is renewable and creates less harmful emissions than conventional diesel. Biodiesel blends – usually B20 or below, have been the most commonly used biodiesel blends. In current study, the kinetic mechanism of n-decane/α-methylnaphthalene (AMN)/methyl-decanoate (MD) blend is developed and validated as the surrogate for biodiesel/diesel blends. The IDEA reference fuel (70% n-decane/30% AMN by liquid volume) was formulated in the past as a two-component diesel surrogate fuel. A comprehensive and compact oxidation model for the IDEA reference fuel is developed. One important fuel-fuel interaction pathway via reaction pathway of A2CH2 + HO2 is observed and detailed discussed. The IDEA blends are validated by comprehensive target experiments for n-decane, AMN, and the AMN/n-decane blends. Ignition delay times, flame speeds, and species composition in jet stirred reactor and counter flow flames are successfully simulated for a broad range of temperatures (500-2000 K) and pressures (1-50 bar). The simulations of the IDEA blend with current mod-el show acceptable agreement when compared with different experiments of ignition delay times for diesel fuels as well as flame speed experiments. With a chain of ten carbon atoms and a methyl-ester group attached, MD is considered as a one-component surrogate fuel for biodiesel. A comprehensive and compact kinetic model for MD is developed. The mechanism is critically tested by comparison of model predictions with experimental data over a wide temperature (500 to 1500 K) and pressure (1 to 20 bar) range and for different fuel/oxidizer ratios. The good maintenance of chemical information during the reduction has been confirmed by simulation results, as well as the sensitivity and flow analyses performed using the detailed and the skeletal model. The MD model is compared with available experimental ignition delay times of biodiesel fuels. The good agreement between the simulations and the experiments proves that this model is a reliable kinetic model for simulations, either used by itself or in combination with IDEA blend. To improve the mechanism analysis, this thesis introduces a new three-stage reactive flow analysis. The final skeletal n-decane/AMN/MD blend with skeletal base mechanism includes 295 species and 3500 reactions by using the CGR approach. Based on the above validations and comparisons, current blend is considered as one surrogate for biodiesel/diesel blends that is suitable for improving kinetic understanding and for application in engine simulations.
Safety evaluation of truss structures depends upon the determination of the axial forces and corresponding stresses in axially loaded members. Due to presence of damages, change in intended use, increase in service loads or accidental actions, structural assessment of existing truss structures is necessary. Precise identification of the stresses plays a crucial role for the preservation of historic truss structures. The assessment measures require non-destructiveness, minimum intervention and practical applicability.
Motivated by the preservation of existing truss−type constructions composed of axially loaded slender members, the present work aims to develop a non-destructive methodology to identify the axial forces or corresponding stress states in iron and steel truss structures. The approach is based on vibration measurements and the finite element method combined with optimization techniques.
After a state of the art review, numerical and experimental studies were carried out in the research work on different partial systems of truss-type structures. The examined aspects included the effects of structural loading on the dynamic performance of truss structures, modelling of joint connections, mode pairing criteria, selection of updating parameters and definition of an objective function, as well as the use of different optimization techniques.
A methodology consisted of a two-stage model updating procedure using optimization techniques was proposed for the determination of multiple member axial forces and estimation of the joint flexibility of truss-type constructions. In the first stage optimization, the validation criterion is based on the experimentally identified global natural frequencies and mode shapes of the truss. Additionally, the axial forces in selected individual members of the truss are used. They are estimated from the natural frequencies and five amplitudes of the corresponding local mode shapes of the members using an analytically−based algorithm. Based on the results of the identified axial forces in the first stage, a second optimization procedure for the joint stiffness is performed. In this stage, the modal parameters of the global natural frequencies and mode shapes are used as validation criterion.
From the results of the investigated systems, the identified axial forces by the proposed methodology agree well with the experimentally measured axial forces. Furthermore, recommendations are given in the work for a guideline of measuring concepts and assessment strategies applied to existing iron and steel truss-type structures.
Intrusion detection is a concept from the field of IT security. Network intrusion detection systems (NIDS) are used in addition to preventative measures, such as firewalls, to enable an automated detection of attacks.
Network security threats often consist of multiple attack phases directed against various components of the network. During each attack phase, varying types of security-related events can be observed at various points in the network. Security monitoring, however, is nowadays essentially limited to the uplink to the internet. Sometimes it is also used to a limited extent at key points within a network, but the analysis methods do not have the same depth as at the uplink. Other areas, such as virtual networks in virtual machines (VMs), are not covered at all, yet. The aim of this thesis has been to improve the detection capability of attacks in local area networks. With a glance at the area of safety engineering, it appears efficient to secure these networks thoroughly and to develop additional monitoring solutions only for the remaining problem cases. This entails several challenges for the analysis of different parts of the TCP/IP stack. The lowermost part of the network stack has to be analyzed for attacks on network components, such as switches and VM bridges. For this, there is still no technology. Although attacks on the layers~2 and 3, such as ARP spoofing and rogue DHCP servers in physical networks, can be controlled to some extent by appropriate switches, equivalent methods are not used in virtual networks. Therefore, a software-defined networking based approach is proposed to counteract the respective attacks, which works for physical and virtual networks. The upper layers are already largely covered by traditional NIDS methods, but the rapidly increasing data rates of local area networks often lead to an uncontrolled discarding of traffic due to overload situations in the monitoring stations.
Therefore, the drawbacks of current optimization approaches are outlined based on a detailed performance profiling of typical intrusion detection systems. A new approach for parallelizing the intrusion detection analysis that copes with the increasing network dynamics is introduced and evaluated. Since further special issues for NIDS particularly go back to the massive use of web technologies in today's networks, a firewall architecture is presented which applies novel NIDS methods based on machine learning to identify web applications and to ward off malicious inputs. The architecture addresses the entire process chain starting from the data transfer with HTTP via the analysis of manipulated web documents to the extraction and analysis of active contents.
Verification of software for Contiki-based low-power embedded systems using software model checking
(2017)
The main building blocks for the internet of things are connected embedded systems. Often these systems are also used in safety critical applications. Therefore, it is particularly important that these devices work according to their specification i.e. they behave as intended. Nowadays, even for simple devices embedded operating systems as Contiki are used to simplify application development and to increase portability between different hardware platforms.
The main objective of this thesis is to present a methodology for the verification of software applications written for the operation system Contiki, taking the system hardware into account. Therefore, software model checking and especially bounded model checking [BCC⁺03] is used as a technique, which allows to formally verify software for embedded systems.
For verifying the software against its specification, it is also necessary to build a model of the system hardware. Thereby, the difficulty is to create a model which is detailed enough to capture the hardware behavior so that the software performs correctly, while keeping the computation effort for the verification process manageable. In this work, the drivers which communicate with the hardware are therefore replaced with abstract models during the verification process. This enables the verification based on an abstract hardware platform independent of specific hardware.
A special role within embedded systems play interrupts. Interrupts are used to save power and can also be used to react on external events. Current methods for verification of interrupt driven software are based on the interleaving model and partial order reduction to reduce the size of the verification problem. This thesis argues that this method is not sufficient for software, whose behavior relies on periodically occurring interrupts. Therefore, in this thesis, a new approach called periodic interrupt modeling is introduced. This approach can be applied automatically and reduces the number of incorrect verification results due to inaccurate modeling. In addition, properties can be proven that depend on the number of occurring interrupts.
Using applications for the Contiki operating system, and based on a verification flow, the approaches toward interrupt modeling are compared.