Search

Verifying imperative programs is hard. A key difficulty is that the specification of what an imperative program does is often intertwined with details about pointers and imperative state. Although there are a number of powerful separation logics that allow the details of imperative state to be captured and managed, these details are complicated and reasoning about them requires significant time and expertise. In this paper, we take a different approach: a memory-safe type system that, as part of type-checking, extracts functional specifications from imperative programs. This disentangles imperative state, which is handled by the type system, from functional specifications, which can be verified without reference to pointers. A key difficulty is that sometimes memory safety depends crucially on the functional specification of a program; e.g., an array index is only memory-safe if the index is in bounds. To handle this case, our specification extraction inserts dynamic checks into the specification. Verification then requires the additional proof that none of these checks fail. However, these checks are in a purely functional language, and so this proof also requires no reasoning about pointers.

Reconstructing the circuit model presents a challenge for circuits with unknown functional specifications. The circuit is thought of as a black box that, given an input, produces an output. The model of the circuit, on the other hand, is unknown. Given a set of inputs and their corresponding outputs, the goal is then to recover the circuit specification while maximizing reconstruction accuracy. This process is computationally difficult, and it becomes even more difficult to solve when only a subset of inputs and outputs are provided, as is the case in many large and complex circuits. This issue is addressed in this paper: Reconstructing the model of a circuit from a set of components and observations describing its inputs and outputs. Previous work proposed a decision tree approach, but this approach only works when the entire set of inputs and outputs is available. Nonetheless, for most systems, this requirement is unrealistic. To address this challenge, we propose an active learning approach and applying orthogonal arrays of fractional factorial design to sample labeled data for learning the reconstructed circuit. Evaluation on 9 well known circuits shows the benefits of the proposed algorithms in terms of accuracy, run time and the reconstructed circuit model.

The decisions a researcher makes at the model building stage are crucial for parameter identification. This paper contains a number of applied tips for solving identifiability problems and improving the strength of DSGE model parameter identification by fine-tuning the (1) choice of observables, (2) functional specifications, (3) model features and (4) choice of structural shocks. We offer a formal approach based on well-established diagnostics and indicators to uncover and address both theoretical (yes/no) identifiability issues and weak identification from a Bayesian perspective. The concepts are illustrated by two exemplary models that demonstrate the identification properties of different investment adjustment cost specifications and output-gap definitions. Our results provide theoretical support for the use of growth adjustment costs, investment-specific technology, and partial inflation indexation.

CD4(+)Foxp3(+) regulatory T (Treg) cells are key players in keeping excessive inflammation in check. Mounting evidence have shown that Treg cells exert a much more diverse function in both immunological and non-immunological processes. The development, maintenance and functional specification of Treg cells are regulated by multilayered factors, including antigens and TCR signaling, cytokines, epigenetic modifiers and transcription factors (TFs). In the review, we will focus on TFs by summarizing their unique and redundant roles in Treg cells under physiological and pathophysiological conditions. We will also discuss the recent advances of Treg trajectories between lymphoid organs and non-lymphoid tissues. This review will provide an updated view of the newly identified TFs and new functions of known TFs in Treg biology.

This paper derives firms’ desired rate of utilization from an explicit maximization of a conjectured rate of profit at the micro level. Invoking a strategic complementarity, desired utilization is thus an increasing function of not only the profit share but also the actual utilization. Drawing on recent empirical material and a straightforward functional specification, the model is subsequently numerically calibrated. In particular, this ensures a unique solution for a steady-state position in which the actual and the endogenous desired rates of utilization coincide. On the other hand, it turns out that the anticipated losses of firms by not producing at the desired level are rather small. Hence there may be only weak pressure on them to close a utilization gap in the ordinary way by suitable adjustments in fixed investment. It is indicated that this finding may serve Kaleckian economists as a more rigorous justification for viewing their equilibria as pertaining to the long run, even if they allow actual utilization to deviate persistently from desired utilization.

Diese Arbeit beschäftigt sich mit den kritischen Erfolgsfaktoren der Einzel- und Generalunternehmer-Vergabe von Bauleistungen im öffentlichen Bereich und wie sich diese auf die beiden Vergabearten auswirken. Die kritischen Erfolgsfaktoren behandeln die vorherrschenden Problematiken und üblichen Vorkommnisse (Planungsprobleme, Vergabestrategien, Stärken und Schwächen der Projektbeteiligten, Koordinierung, Schnittstellen, Zeitfaktor, Kosten und Gewährleistung), die in der österreichischen Baubranche auftreten. Neben der Erläuterung der einzelnen Projektbeteiligten, die bei einem Bauprozess mitwirken, werden die Anforderungen eines Bauprojektes durch den Bauherrn in Form von Projektzielen beleuchtet. Des Weiteren werden die verschiedenen und die in Österreich üblichen Bauabwicklungsmodelle sowie die Vergabearten nach dem Bundesvergabegesetz 2018 näher beschrieben. Eine umfangreiche, anonyme Online-Befragung von Experten, die in den drei Tätigkeitsbereichen Auftraggeber, Konsulenten und Auftragnehmer in der Baubranche vertreten sind, wurde durchgeführt. Diese Umfrage zeigt die Tendenzen der Vergabe von Einzelgewerken oder eines Generalunternehmers. Als Resümee werden die beiden Vergabearten gegenübergestellt und die für als sinnvoll betrachteten Konstellationen für die Abwicklung von Bauvorhaben vorgeschlagen. This thesis deals with the critical success factors of the single- and prime contractor award of construction services in the public sector and how these affect the two types of awards. The critical success factors deal with the prevailing problems and common occurrences (planning problems, award strategies, strengths and weaknesses of the project participants, coordination, interfaces, time factor, costs and warranty) that occur in the Austrian construction industry. In addition to the explanation of the individual project participants who are involved in a construction process, the requirements of a construction project are highlighted by the client in the form of project goals. Furthermore, the various construction management models that are customary in Austria and the types of procurement according to the Federal Procurement Act 2018 are described in more detail. An extensive, anonymous online survey of experts representing the three areas of activity of employees, consultants and contractors in the construction industry was carried out. This survey shows the tendencies in the awarding of individual trades or a general contractor. As a summary, the two types of awards are compared, and the constellations considered sensible for the execution of construction projects are proposed. Abweichender Titel laut Übersetzung der Verfasserin/des Verfassers Masterarbeit Wien, FH Campus Wien 2022

The cumulative stack-up of geometric variations in mechanical systems can be modeled summing and intersecting sets of constraints. These constraints derive from tolerance zones or from contact restrictions between parts. The advantage of this approach is its robustness for treating any kind of mechanisms, including the over-constrained ones. However, the sum of constraints, which must be computed when simulating the accumulation of defects in serial joints, is a very time-consuming operation. In previous papers, we proposed to virtually limit the degrees of freedom of the toleranced features and joints turning the polyhedra into polytopes to avoid manipulating unbounded objects. Even though this approach enables to process the whole mechanism, it also introduces bounding or cap facets which increase the complexity of the operand sets after each operation until becoming far too significant. In this work, we introduce algorithms summing, intersecting and testing inclusions. As they operate on sets of constraints using unbounded polyhedral objects, we identify the smaller sub-space in which the projection of these operands are bounded sets. Calculating the sum in this sub-space allows reducing the operands complexity significantly and consequently the computational time. Then, checking the final inclusion informs us not only about the compliance of the mechanism tolerances with respect to the functional specification but also to quantify how far we are from this target. Finally prismatic polyhedra integrate ISO and contacts specifications in a very natural way and are able to perform a full kinematic analysis of the mechanism. After presenting the geometric properties on which this approach rely, we demonstrate it on an industrial case. Then we compare the computation times, prove the robustness of the new method and show how to quantify the functional condition compliance with respect to a given set of tolerances.

A crucial step for the safety verification and validation process of Highly Automated Vehicles (HAV) is the definition of the Operational Design Domain (ODD). The ODD specifies the space of operation for the system under consideration, mainly based on the traffic environment and the subject vehicle behavior. Current approaches are able to describe the static traffic environment by representing the individual elements of the scenery, but they do not manage to identify the behavior-relevant information from these elements. This information is important for the functional specification of the system. We introduce a structure of behavioral attributes that assigns the behavior relevant information to the scenery. This enables the capturing of the limits of the behavioral demand of the scenery, which serves as a basis for the Behavior-Semantic Scenery Description (BSSD). The advantage of this behavioral abstraction process is a reduction in complexity while preserving the behavior-relevant information content. We illustrate this advantage by applying the behavioral attributes to different real-world intersection examples.