Timing Analysis for DAG-based and GFP Scheduled Tasks

Modern embedded systems have made the transition from single-core to multi-core architectures, providing performance improvement via parallelism rather than higher clock frequencies. DAGs are considered among the most generic task models in the real-time domain and are well suited to exploit this parallelism. In this paper we provide a schedulability test using response-time analysis exploiting exploring and bounding the self interference of a DAG task. Additionally we bound the interference a high priority task has on lower priority ones

Magnification relations for Kerr lensing and testing Cosmic Censorship

A Kerr black hole with mass parameter m and angular momentum parameter a acting as a gravitational lens gives rise to two images in the weak field limit. We study the corresponding magnification relations, namely the signed and absolute magnification sums and the centroid up to post-Newtonian order. We show that there are post-Newtonian corrections to the total absolute magnification and centroid proportional to a/m, which is in contrast to the spherically symmetric case where such corrections vanish. Hence we also propose a new set of lensing observables for the two images involving these corrections, which should allow measuring a/m with gravitational lensing. In fact, the resolution capabilities needed to observe this for the Galactic black hole should in principle be accessible to current and near-future instrumentation. Since a/m >1 indicates a naked singularity, a most interesting application would be a test of the Cosmic Censorship conjecture. The technique used to derive the image properties is based on the degeneracy of the Kerr lens and a suitably displaced Schwarzschild lens at post-Newtonian order. A simple physical explanation for this degeneracy is also given.Comment: 13 pages, version 2: references added, minor changes. To appear in Phys. Rev.

The Economics of Behavior. Essays on the Organizational Effects of Identification, Wage Expectations, and Fairness Concerns

This thesis deals with behavioral factors that critically influence the outcomes of organizational practices. Our research features a mix of different methods combining theoretical arguments with evidence from field and experimental data to investigate to what extent employees' decisions are driven by psychological motives such as emotional attachment, expectations, and fairness perceptions. The combination of methods allows us to analyze a problem from different perspectives and to gather evidence from complementary sources, thus giving a more complete picture of the question of interest. We show that behavioral mechanisms play a crucial role in determining the consequences of organizational practices, often affecting them in unexpected ways. Chapter 2 studies the role of employees' identification with their employer as a component of match quality for determining job satisfaction, effort provision, job search, bargaining behavior, and resulting wage growth. In a first step, we analyze a stylized formal model, which integrates the emotional attachment to the employer into the employee's utility function. As a second step, we test the theoretically predicted patterns using a novel employer-employee panel dataset. We take advantage of a validated survey measure of “affective commitment” as a proxy for employee identification. Consistent with our theoretical model, we find that, for committed employees, absolute wage is significantly less predictive for job satisfaction. Additionally, we observe that employees with higher commitment have significantly fewer absence days and more hours of unpaid overtime, which represent our effort measures. Moreover, higher commitment predicts a lower wage growth in the future and is associated with a lower propensity to search for alternatives, receive an external offer, and to quit the current employment voluntarily. However, we also find evidence that employees can successfully exploit their higher threat point when they have obtained an external offer, thus resulting in increased wage growth. This relationship seems to be even more pronounced for more committed employees. In chapter 3, we experimentally analyze the effect of quota interventions on subjective evaluations in a peer-review context. Our results show that quotas have a significant impact on peer-review behavior. First, we find that quotas affect the overall level of peer-reviews provided. This effect, however, depends on the perceived procedural fairness which varies between treatments. Second, we show that quotas lead to systematic biases in peer-reviews against the affirmed group. They receive significantly less favorable peer-reviews relative to their non-affirmed peers. This second effect is not related to the perceived procedural fairness since it remains robust across both quota treatments. Instead, these distortions seem to be a result of the enhanced competition among affirmed inviduals under the quota regime as they are fully driven by peer-reviews provided by affirmed individuals to other affirmed peers. Lastly, we study spillover effects of quotas on giving in an additional dictator experiment after the conclusion of the main experiment. We find that a quota in the previous experiment significantly reduces altruistic behavior among individuals that were affirmed before. Our study gives insights into potential negative side effects and shows that quotas can lead to distortions in subjective peer-reviews, and therefore harm the group that is supposed to benefit from the quota. Additionally, we provide evidence of negative spillover effects of quotas to non-competitive environments. We study the effect of training participation on employees' fair wage expectations, effort provision, and finally productivity in chapter 4. We theoretically argue that because of the increased productivity potential, employees hold higher fair wage expectations after receiving training. We use an extensive linked employer-employee survey dataset to study the relationship between training participation and future wage expectations. The analyses of our field dataset indicate that employees hold higher future wage expectations as a result of training participation. Our experimental results confirm this relationship and give additional insights into the behavioral mechanisms behind training participation. We find that even though training is effective in increasing the skills and thus productivity potential of an employee, this does not neccessary translate into increased productivity for the employer. Instead, our results show that trained employees negatively adjust effort both on the extensive and intensive margin. Additional analyses reveal that, in line with our theoretical considerations, the difference between the actual and the perceived fair wage is a determinant of whether or not an employee releases his productivity potential. Thus, these results indicate that fairness concerns can impair the positive productivity effects of training. The research presented in this thesis demonstrates the importance of psychological factors for employer-employee interactions and the outcomes of managerial measures. We show that it is critical to understand the behavioral mechanisms at play in order to achieve the intended results and potentially take precautionary actions to prevent adverse effects

Runtime CRPD management for rate-based scheduling

Temporal isolation is an increasingly relevant con- cern in particular for ARINC-351 and virtualisation- based systems. Traditional approaches like the rate- based scheduling framework RBED do not take into account the impact of preemptions in terms of loss of working set in the acceleration hardware (e.g. caches). While some improvements have been suggested in the literature, they are overly heavy in the presence of small high-priority tasks such as interrupt service routines. Within this paper we propose an approach enabling adaptive assessment of this preemption delay in a tem- poral isolation framework with special consideration of capabilities and limitations of the approach.This work was supported by the Portuguese Science and Technology Foundation (FCT) (CISTER FCT-608) and ARTEMIS-JU (RECOMP project ARTEMIS/0202/2009

A single parameter representation of hygroscopic growth and cloud condensation nucleus activity – Part 2: Including solubility

The ability of a particle to serve as a cloud condensation nucleus in the atmosphere is determined by its size, hygroscopicity and its solubility in water. Usually size and hygroscopicity alone are sufficient to predict CCN activity. Single parameter representations for hygroscopicity have been shown to successfully model complex, multicomponent particles types. Under the assumption of either complete solubility, or complete insolubility of a component, it is not necessary to explicitly include that component's solubility into the single parameter framework. This is not the case if sparingly soluble materials are present. In this work we explicitly account for solubility by modifying the single parameter equations. We demonstrate that sensitivity to the actual value of solubility emerges only in the regime of 2×10<sup>−1</sup>–5×10<sup>−4</sup>, where the solubility values are expressed as volume of solute per unit volume of water present in a saturated solution. Compounds that do not fall inside this sparingly soluble envelope can be adequately modeled assuming they are either infinitely soluble in water or completely insoluble

Influences on the fraction of hydrophobic and hydrophilic black carbon in the atmosphere

Black carbon (BC) is a short term climate forcer that directly warms the atmosphere, slows convection, and hinders quantification of the effect of greenhouse gases on climate change. The atmospheric lifetime of BC particles with respect to nucleation scavenging in clouds is controlled by their ability to serve as cloud condensation nuclei (CCN). To serve as CCN under typical conditions, hydrophobic BC particles must acquire hygroscopic coatings. However, the quantitative relationship between coatings and hygroscopic properties for ambient BC particles is not known nor is the time scale for hydrophobic-to-hydrophilic conversion. Here we introduce a method for measuring the hygroscopicity of externally and internally mixed BC particles by coupling a single particle soot photometer with a humidified tandem differential mobility analyzer. We test this technique using uncoated and coated laboratory generated model BC compounds and apply it to characterize the hygroscopicity distribution of ambient BC particles. From these data we derive that the observed number fraction of BC that is CCN active at 0.2% supersaturation is generally low in an urban area near sources and that it varies with the trajectory of the airmass. We anticipate that our method can be combined with measures of air parcel physical and photochemical age to provide the first quantitative estimates for characterizing hydrophobic-to-hydrophilic conversion rates in the atmosphere.Peer reviewe

A single parameter representation of hygroscopic growth and cloud condensation nucleus activity – Part 3: Including surfactant partitioning

Atmospheric particles can serve as cloud condensation nuclei in the atmosphere. The presence of surface active compounds in the particle may affect the critical supersaturation that is required to activate a particle. Modelling surfactants in the context of Köhler theory, however, is difficult because surfactant enrichment at the surface implies that a stable radial concentration gradient must exist in the droplet. In this study, we introduce a hybrid model that accounts for partitioning between the bulk and surface phases in the context of single parameter representations of cloud condensation nucleus activity. The presented formulation incorporates analytical approximations of surfactant partitioning to yield a set of equations that maintain the conceptual and mathematical simplicity of the single parameter framework. The resulting set of equations allows users of the single parameter model to account for surfactant partitioning by applying minor modifications to already existing code