It is a well-known fact that project activities are subject to considerable uncertainty, which may lead to multiple schedule disruptions during project execution. As a result, the random nature of activity durations has been the subject of numerous research efforts since the introduction of the initial PERT. A common problem which arises in project management is the fact that the planned schedule is often disrupted by several uncontrollable factors like weather conditions, other environmental factors, additional time that might be required for rework and correction of detected defects. As a result, project managers are often unable to meet the promised completion dates. It is therefore vital to take into account such possible disruptions and their potential negative consequences at the project schedule design stage. Hence, the ability of the pre-schedule to absorb disruptions may be very important in such settings. At this point two new criteria are used in modern scheduling literature: &quot / robustness&quot / and &quot / stability&quot / . In this thesis, we propose several stability measures. These measures are embedded in a tabu search algorithm to generate stable schedules in a multi resource environment subject to random disruptions.

La notion de robustesse peut se définir par le maintien des performances et de la santé quelles que soient les conditions d’environnement. Le sevrage constitue la phase où la plus grande quantité d’antibiotiques est utilisée car il est source de perturbations multiples pour le porcelet. L’identification de porcs robustes permettrait d’envisager des soins spécifiques et/ou une sélection génétique sur ce caractère. Les objectifs de cette thèse étaient d’identifier certains marqueurs physiologiques associés à la robustesse du porcelet au sevrage et de prédire cette robustesse par des variables physiologiques décrivant ces réponses mesurées avant et après sevrage. Pour répondre à cet objectif, des variables physiologiques ont d’abord été mesurées dans des environnements très divers puis celles associées à la robustesse ont été identifiées. Une première étude a été conduite en installation expérimentale visant à étudier les effets de l’âge, des conditions de sevrage et de la santé sur l’évoPar ailleurs, dans une deuxième étude, des variables physiologiques ont été mesurées dans 16 élevages commerciaux autour du sevrage. Les performances de croissance et le statut sanitaire étaient les 2 facteurs de variations d’élevages contrôlés. L’analyse des données a permis de mettre en évidence une forte influence du statut sanitaire sur les variables physiologiques mesurées autour du sevrage. Des variables descriptives du statut oxydant, du statut métabolique et de l’activation du système immunitaire ont été associées à la robustesse du porcelet au sevrage. Ainsi, les porcelets les plus / The concept of robustness can be defined as the ability to maintain performances and health whatever environmental conditions. Weaning is the step where the biggest part of antibiotics is used because it is the source of multiple perturbations for the piglet. The identification of robust pigs could allow settling specific care and/or genetic selection on this criteria. The objectives of this thesis were to identify physiological parameters associated with the robustness of piglet at weaning and to predict this robustness by biological variables describing those measured responses before and after weaning. To answer to this objective, physiological variables were first measured in very different environments and, then, those ones associated with the robustness were identified. A first experiment was realized in experimental unit, aiming to study the effects of age, weaning conditions and health on the evolution of blood variables describing immune and metabolic status, stress and oxidatGrowth performances and health status were the two controlled factors of variations of farms. The analysis of data allowed us to show a high influence of health status on physiological variables around weaning. Some variables describing oxidative status, metabolic status and the activation of immune system were associated with the robustness of piglet at weaning. Thus, the most robust piglets are those ones who, in favorable or unfavorable environments, have a capacity to limit their oxidative stress, to mobilize less body reserves and to activate quickly their immune system. Those variables

abstract: For this thesis a Monte Carlo simulation was conducted to investigate the robustness of three latent interaction modeling approaches (constrained product indicator, generalized appended product indicator (GAPI), and latent moderated structural equations (LMS)) under high degrees of nonnormality of the exogenous indicators, which have not been investigated in previous literature. Results showed that the constrained product indicator and LMS approaches yielded biased estimates of the interaction effect when the exogenous indicators were highly nonnormal. When the violation of nonnormality was not severe (symmetric with excess kurtosis < 1), the LMS approach with ML estimation yielded the most precise latent interaction effect estimates. The LMS approach with ML estimation also had the highest statistical power among the three approaches, given that the actual Type-I error rates of the Wald and likelihood ratio test of interaction effect were acceptable. In highly nonnormal conditions, only the GAPI approach with ML estimation yielded unbiased latent interaction effect estimates, with an acceptable actual Type-I error rate of both the Wald test and likelihood ratio test of interaction effect. No support for the use of the Satorra-Bentler or Yuan-Bentler ML corrections was found across all three methods. / Dissertation/Thesis / M.A. Psychology 2010

Doctor of Philosophy / Department of Electrical and Computer Engineering / Don M. Gruenbacher / Caterina M. Scoglio / As today's networks are no longer individual networks, networks are less robust towards failures and attacks. For example, computer networks and power networks are interdependent. Computer networks provide smart control for power networks, while power networks provide power supply. Localized network failures and attacks are amplified and exacerbated back and forth between two networks due to their interdependencies. This dissertation focuses on finding solutions to enhance network robustness. Software-defined networking provides a programmable architecture, which can dynamically adapt to any changes and can reduce the complexities of network traffic management. This architecture brings opportunities to enhance network robustness, for example, adapting to network changes, routing traffic bypassing malfunction devices, dropping malicious flows, etc. However, as SDN is rapidly proceeding from vision to reality, the SDN architecture itself might be exposed to some robustness threats. Especially, the SDN control plane is tremendously attractive to attackers, since it is the "brain" of entire networks. Thus, researching on network robustness helps protect network from a destructive disaster. In this dissertation, we first build a novel, realistic interdependent network framework to model cyber-physical networks. We allocate dependency links under a limited budget and evaluate network robustness. We further revise a network flow algorithm and find solutions to obtain a basic robust network structure. Extensive simulations on random networks and real networks show that our deployment method produces topologies that are more robust than the ones obtained by other deployment techniques. Second, we tackle middlebox chain problems using SDN. In computer networks, applications require traffic to sequence through multiple types of middleboxes to accomplish network functionality. Middlebox policies, numerous applications' requirements, and resource allocations complicate network management. Furthermore, middlebox failures can affect network robustness. We formulate a mixed-integer linear programming problem to achieve a network load-balancing objective in the context of middlebox policy chain routing. Our global routing approach manages network resources efficiently by simplifying candidate-path selections, balancing the entire network and using the simulated annealing algorithm. Moreover, in case of middlebox failures, we design a fast rerouting mechanism by exploiting the remaining link and middlebox resources locally. We implement proposed routing approaches on a Mininet testbed and evaluate experiments' scalability, assessing the effectiveness of the approaches. Third, we build an adversary model to describe in detail how to launch distributed denial of service (DDoS) attacks to overwhelm the SDN controller. Then we discuss possible defense mechanisms to protect the controller from DDoS attacks. We implement a successful DDoS attack and our defense mechanism on the Mininet testbed to demonstrate its feasibility in the real world. In summary, we vertically dive into enhancing network robustness by constructing a topological framework, making routing decisions, and protecting the SDN controller.

abstract: In this thesis we deal with the problem of temporal logic robustness estimation. We present a dynamic programming algorithm for the robust estimation problem of Metric Temporal Logic (MTL) formulas regarding a finite trace of time stated sequence. This algorithm not only tests if the MTL specification is satisfied by the given input which is a finite system trajectory, but also quantifies to what extend does the sequence satisfies or violates the MTL specification. The implementation of the algorithm is the DP-TALIRO toolbox for MATLAB. Currently it is used as the temporal logic robust computing engine of S-TALIRO which is a tool for MATLAB searching for trajectories of minimal robustness in Simulink/ Stateflow. DP-TALIRO is expected to have near linear running time and constant memory requirement depending on the structure of the MTL formula. DP-TALIRO toolbox also integrates new features not supported in its ancestor FW-TALIRO such as parameter replacement, most related iteration and most related predicate. A derivative of DP-TALIRO which is DP-T-TALIRO is also addressed in this thesis which applies dynamic programming algorithm for time robustness computation. We test the running time of DP-TALIRO and compare it with FW-TALIRO. Finally, we present an application where DP-TALIRO is used as the robustness computation core of S-TALIRO for a parameter estimation problem. / Dissertation/Thesis / M.S. Computer Science 2013

Abstract The activity of neurons is critically dependent upon the suite of voltage-dependent ion channels expressed in their membranes. In particular, voltage-gated K+ channels are extremely diverse in their function, contributing to the regulation of distinct aspects of neuronal activity by shaping the voltage responses. In this study the role of K+ channels in neural coding is investigated in Drosophila photoreceptors by using biophysical models with parameters derived from the electrophysiological experiments. Due to their biophysical properties, the Shaker channels attenuate the fast transients and amplify the slower signal components, enabling photoreceptors to use their voltage range more effectively. Slow delayed rectifier channels, shown to be encoded by the Shab gene, activate at high light intensities, thereby attenuating the light-induced depolarization and preventing response saturation. Activation of Shab channels also reduces the membrane time constant making it possible to encode faster events. Interactions between the voltage-gated K+ channels and the currents generated by the light induced conductance (LIC) were investigated during naturalistic stimulation in wild type and Shaker mutant photoreceptors. It is shown that in addition to eliminating the Shaker current, the mutation increased the Shab current and affected the current flowing through the LIC. Part of these changes could be attributed to direct feedback from the Shaker channels via the membrane potential. However, it is suggested that also other changes may occur in the LIC due to mutation in K+ channels, possibly during photoreceptor development. Comparison of the Shaker and Shab mutant photoreceptors with the wild type revealed that a concurrent decrease in the steady-state input resistance followed from deletion of the voltage-gated K+ channels. This allowed partial compensation of the compression and saturation caused by the loss of Shaker channels and it maintained the characteristics of the light-voltage relationship in Shab mutant photoreceptors. However, wild type properties were not fully restored in either mutant. Indeed, decreased input resistance results in reduced efficiency of neural processing, assessed by the metabolic cost of information. Results of this study demonstrate the importance of the voltage-gated K+ channels for neural coding precision and highlight the robustness of neuronal information processing gained through regulation of the electrical properties.

In the experimental ITER fusion reactor, currently under construction in Cadarache, France, components close to the plasma will get activated and contaminated over time. Therefore, these components will need to be maintained remotely in a so called hot cell facility. The maintenance will be executed according to step-by-step procedures, with every procedure meticulously validated and formally described in an Operation Sequence Description (OSD). To support formal validation, OSDs are to be captured in an ITER-dedicated Structured Language (SL), a form of domain specific programming language. The Remote Handling Study Centre (RHSC), located at FOM institute DIFFER, Nieuwegein, The Netherlands, has an ITER Remote Handling Control Room representative setup which connects to a virtual ITER Hot Cell back-end environment. In this setup, Remote Handling maintenance scenarios and procedures can be tested under realistic conditions. In this thesis, a Structured Language for ITER maintenance is proposed, implemented as a prototype to capture several realistic operational sequences from existing projects, and integrated in the RHSC workflow. The Structured Language programs are converted to schedulable tasks, by inferring their resource usage and time duration from the structured task descriptions. These tasks are then scheduled using a proposed set of scheduling heuristics. The resulting schedule is subsequently submitted to many simulated executions, with random variation in the execution time of individual tasks. The variation that is applied in the execution time, is based on representative task execution times was measured for a recent and repetitive set of maintenance tasks performed at JET. It is shown that inserting a certain amount of slack in the schedule improves its robustness. ITER maintenance scheduling should account for uncertainty by including slack in the resulting planning.

Purpose: In the last decade, supply chains of many global firms have been exposed to severe and costly supply chain disruptions. Triggered by either a manmade or a natural disaster, these disruptions are often a result of the increased network complexity and interdependency. One of the many contributing factors to this increased network complexity is the conscious effort by organizations to over optimise their efficiency and performance. The field of supply chain resilience, robustness and vulnerability studies, a new and growing area of knowledge, is contributing towards discovering the causes leading to supply chain disasters and measures to tackle them. Criticized to be highly fragmented and fraught with conceptual ambiguity, the filed has been evolving by incorporating vulnerability and resilience research from other interdisciplinary domains. This present research aims at mapping the intellectual territory of the resilience, robustness and vulnerability domain by conducting a literature review. The review also aims to establish a conceptual clarity in the definition of terms and constructs relevant to the field and to discover conceptual and methodological gaps in the existing body of literature. Design/methodology/approach: This literature review is conducted using a systematic review approach which benefits from a clearly defined audit and decision trail. After filtering through 2077 titles, the review is taken up for 43 articles. Findings: The review demonstrates that the drivers of vulnerability and strategies to tackle it can be grouped into three themes, Structural, Operational and Strategic. The review also demonstrates that the field is still plagued with conceptual ambiguity. By the analysis of the findings, a number of research directions were identified. Research limitations/implications: Major limitations to this study were the associated personal bias in quality assessment of included and excluded articles. Also, due to blurred definitions of terms and constructs in the literature, the thematic classification of findings could be challenged. Lastly, it cannot be stated with conviction that the chosen 43 articles are sufficient. Practical implications: This research highlights the future conceptual and methodological prospects in the field of resilience, robustness and vulnerability. The direction of structural research proposed in the thesis has a very high potential to secure future supply chains. Originality/value: This review is first to address the issue of SCV, SCRel and SCRob. The review provides an extensive overview of the present extant of the vulnerability, robustness research and it proposes a thematic framework to further extend the knowledge in this filed.

Abstract The Generalized Predictive Controller in transfer function representation is proposed for the cascade control task. The recommended cascade GPC (CGPC) applies one predictor and one cost function that results in several advantageous features: The disturbance regulations of the inner and the outer loops can be totally decoupled; The inner disturbance regulation is well damped, the typical overshoot of the traditional cascade control structure is avoided; The robustness properties of the inner and the outer loops can be designed separately; The anti-windup properties of the CGPC are exactly as perfect as in the case of the simple SISO GPC. The typical problem of the saturation in the inner loop, resulting in modeling error for the outer loop, is prevented. The CGPC was applied as the oxygen controller of a pilot fluidized bed boiler. The investigation is based on simulation experiments and on experiments on a pilot scale boiler. In another simulation experiment, the CGPC was applied as the temperature controller of at a steam superheater stage. The results of the experiments well illustrated the power of the proposed cascade control algorithm.

Water resources managers are required to develop comprehensive water resource plans based on severely uncertain information of the effects of climate change on local hydrology and future socio-economic changes to localised demand. In England and Wales, current water resource planning methodologies include a headroom estimation process separate from water resources simulation modelling. This process quantifies uncertainty based on only one point of an assumed range of deviations from the expected climate and projected demand 25 years into the future. The research presented herein addresses this problem by developing an integrated the Water Resources Planning Robustness Assessment (WRP-RA) method based on Information-Gap Decision Theory (IGDT) to quantitatively assess the robustness of various supply side and demand side management options over a broad range of plausible futures. Findings show that beyond the uncertainty range explored with the headroom method, a preference reversal can occur, i.e. some management strategies that underperform at lower uncertainties, outperform at higher levels of uncertainty. Also, some management strategies that perform relatively well within the headroom range of uncertainty, fail just beyond this range. Additionally, this thesis demonstrates that when 50% or more of the population adopts demand side management in the form of efficiency related measures and/or innovative options such as rainwater collection and/or greywater reuse, the robustness of a management strategy can be greatly improved as can its ability to recover after a drought episode. The use of Multi-Criteria Decision Analysis shifts the focus away from reservoir expansion options and large-scale river abstractions that perform best in regards to water availability, to strategies that include innovative demand side management actions of rainwater collection and greywater reuse as well efficiency measures along with more traditional supply-side schemes. Therefore, this thesis illustrates how the WRP-RA can offer a comprehensive picture of the relative robustness of management strategies to more extreme supply/demand futures. The knowledge of which options and collections of options perform better in response to higher demands and lower supplies offers insight into more secure long term investment strategies.