Unemployment Benefits and the Duration of Unemployment in East Germany

This paper studies the impact of unemployment benefits on unemployment duration for East Germany using data from the German Socio-Economic Panel. It concentrates on exit from unemployment into employment. Estimation results of a discrete-time hazard rate model imply that moderate cuts in the replacement rate raise the hazards by little. The effect of the replacement rate on the hazards becomes weaker the longer people are unemployed. The threat of periods of benefit sanction could explain this. The hazards are not generally declining in time until exhausting unemployment insurance (UI) benefits, but rise just prior to exhausting UI

Towards a Formal Model of Privacy-Sensitive Dynamic Coalitions

The concept of dynamic coalitions (also virtual organizations) describes the temporary interconnection of autonomous agents, who share information or resources in order to achieve a common goal. Through modern technologies these coalitions may form across company, organization and system borders. Therefor questions of access control and security are of vital significance for the architectures supporting these coalitions. In this paper, we present our first steps to reach a formal framework for modeling and verifying the design of privacy-sensitive dynamic coalition infrastructures and their processes. In order to do so we extend existing dynamic coalition modeling approaches with an access-control-concept, which manages access to information through policies. Furthermore we regard the processes underlying these coalitions and present first works in formalizing these processes. As a result of the present paper we illustrate the usefulness of the Abstract State Machine (ASM) method for this task. We demonstrate a formal treatment of privacy-sensitive dynamic coalitions by two example ASMs which model certain access control situations. A logical consideration of these ASMs can lead to a better understanding and a verification of the ASMs according to the aspired specification.Comment: In Proceedings FAVO 2011, arXiv:1204.579

System requirements analysis of train dispatching protocols with Ontological Hazard Analysis

Sieker B. Systemanforderungsanalyse von Bahnbetriebsverfahren mit Hilfe der Ontological Hazard Analysis am Beispiel des Zugleitbetriebs nach FV-NE. Bielefeld (Germany): Bielefeld University; 2010.The Ontological Hazard Analysis (OHA) is a specification and analysis method for system safety requirements, based on many small but rigorous refinement steps and causal analysis. This development sequence is applied to train-dispatching protocols as defined in the German railway standard FV-NE. Ontological Hazard Analysis is a method for safety-requirements derivation and analysis that allows for logical traceability of safety requirements through system development through to (at least) design. It uses formal refinement and requires methods from formal logics, in particular many-sorted logics that use a number of different axioms.Eisenbahnregelwerke sind traditionell in natürlicher Sprache verfasst. Dies führt zu zahlreichen Problemen beim Erstellen und Verifizieren von Lasten- und Pflichtenheften und bei der unzweideutigen Spezifikation von Systemen für ein bestimmtes Betriebsverfahren. Die Ontological Hazard Analysis ist eine Methode, mit der sich durch formale Verfeinerung ("Formal Refinement") vollständige Spezifikationen der Safety-Requirements erstellen lassen. Mit Hilfe des Model-Checkers SPIN werden weitere Eigenschaften des Systems geprüft, die keine Sicherheitsanforderungen sind. Die Ontological Hazard Analysis ist, anders als gängige andere Verfahren, in der Lage, für ein echtes Bahnbetriebsverfahren eine nahtlose Nachvollziehbarkeit (audit trail) von abstrakten Spezifikationen bis zum Quellcode - abgesehen von möglichen Compilerproblemen auch bis zum Objektcode - zu bieten, und dabei gleichzeitig logische, relative Vollständigkeit der Sicherheitsanforderungen (Safety Requirements) zu garantieren

The Hungarian Unemployment Insurance Benefit System and Incentives to Return to Work

This paper analyses the impact of the Hungarian unemployment insurance (UI) benefit system on the speed of exit from unemployment to regular employment. The duration analysis relies on unemployment spells from two inflow cohorts, which are administered under distinct UI rules. Thus, it exploits a natural experiment to identify disincentive effects. Kaplan-Meier estimates suggest that the benefit reform did not significantly change the transition rates. Moreover, a semi-parametric analysis cannot find remarkable disincentive effects but an entitlement effect. The hazards of men and women rise somewhat in the last two months before they run out of UI benefit

QuantUM: Quantitative Safety Analysis of UML Models

When developing a safety-critical system it is essential to obtain an assessment of different design alternatives. In particular, an early safety assessment of the architectural design of a system is desirable. In spite of the plethora of available formal quantitative analysis methods it is still difficult for software and system architects to integrate these techniques into their every day work. This is mainly due to the lack of methods that can be directly applied to architecture level models, for instance given as UML diagrams. Also, it is necessary that the description methods used do not require a profound knowledge of formal methods. Our approach bridges this gap and improves the integration of quantitative safety analysis methods into the development process. All inputs of the analysis are specified at the level of a UML model. This model is then automatically translated into the analysis model, and the results of the analysis are consequently represented on the level of the UML model. Thus the analysis model and the formal methods used during the analysis are hidden from the user. We illustrate the usefulness of our approach using an industrial strength case study.Comment: In Proceedings QAPL 2011, arXiv:1107.074

Safety-driven system engineering process

Thesis (S. M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2008.MIT Barker Library copy: leaves 82 to 106 bound upside-down.Includes bibliographical references (leaves 56-59).As the demand for high-performing complex systems has increased, the ability of engineers to meet that demand has not kept pace. The creators of the traditional system engineering processes did not anticipate modern complex systems, and the application of traditional processes to complex systems such as spacecraft has repeatedly led to disastrous results. Too often, system safety is considered late in the design process, after much of the design is set. This thesis presents an iterative safety-driven system engineering process to address this problem. The process integrates safety into the design process, ensuring that safety is designed into the system, rather than added on. The techniques used in this process are: I) Intent Specifications, a framework for organizing system development and operational information in a hierarchical structure; 2) the System-Theoretic Accident Modeling and Processes (STAMP) model of accident causation, a framework upon which to base powerful safety engineering techniques; 3) STAMP-based Hazard Analysis (STPA) a novel hazard analysis technique; and 4) SpecTRM-Requirements Language (SpecTRM-RL), a formal modeling language. Intent Specification is used to document the design with complete traceability from system goals, requirements, and constraints to the operational design and software code. The STAMP framework is used to apply concepts from control theory to system engineering. STPA is used to identify hazards and eliminate them or mitigate their effects to ensure a safe system design. Finally, SpecTRM-RL is used to create the blackbox behavior models. An example of this process applied to an outer moon exploration mission is presented (in the form of an intent specification) and discussed. The specification focuses on the design of the control system and functionality of the scientific instruments, while also including a high-level design of the entire spacecraft. The application of the process described in this thesis demonstrates that design decisions are safety-driven, and that the results of the hazard analysis are integrated into all aspects of the design.by Margaret Virginia Stringfellow.S.M