Operations and poly-operations in Algebraic Cobordism

We describe all operations from a theory A^* obtained from Algebraic Cobordism of M.Levine-F.Morel by change of coefficients to any oriented cohomology theory B^* (in the case of a field of characteristic zero). We prove that such an operation can be reconstructed out of it's action on the products of projective spaces. This reduces the construction of operations to algebra and extends the additive case done earlier, as well as the topological one obtained by T.Kashiwabara. The key new ingredients which permit us to treat the non-additive operations are: the use of "poly-operations" and the "Discrete Taylor expansion". As an application we construct the only missing, the 0-th (non-additive) Symmetric operation, for arbitrary p, which permits to sharpen results on the structure of Algebraic Cobordism. We also prove the general Riemann-Roch theorem for arbitrary (even non-additive) operations (over an arbitrary field). This extends the multiplicative case proved by I.Panin.Comment: To appear in Advances in Mathematic

A general solution framework for component commonality problems

Component commonality, the use of the same version of a component across multiple products, is increasingly considered as a promising way to offer high external variety while retaining low internal variety in operations. However, increasing commonality has both positive and negative cost effects, so that optimization approaches are required to identify an optimal commonality level. As a more or less of components influences nearly every process step along the supply chain, it is not astounding that a multitude of diverging commonality problems is investigated in literature, each of which developing a specific algorithm designed for the respective commonality problem considered. The paper on hand aims at a general framework, flexible and effcient enough to be applied to a wide range of commonality problems. Such a procedure basing on a two-stage graph approach is presented and tested. Finally, flexibility of the procedure is shown by customizing the framework to account for different types of commonality problems.Product variety, Component commonality, Optimization, Graph approach

The global operations of European firms

This Policy Brief is part of the EU-EFIGE (European Firms in a Global Economy) project which aims to address policy questions on the casual link between firm characteristics and internationalisation. Authored by Giorgio Barba Navaretti, University of Milan; Matteo Bugamelli, Bank of Italy; Gianmarco Ottaviano, Bruegel Senior Fellow; and Fabiano Schivardi, University of Cagliari, this paper is based on a comprehensive survey of 15,000 firms across seven EU countries. The findings of this paper set the foundation for deeper investigation into key policy challenges affecting European firms on the global stage.

Navigating hotel operations in times of COVID-19

Published versio

Random Quantum Operations

We define a natural ensemble of trace preserving, completely positive quantum maps and present algorithms to generate them at random. Spectral properties of the superoperator Phi associated with a given quantum map are investigated and a quantum analogue of the Frobenius-Perron theorem is proved. We derive a general formula for the density of eigenvalues of Phi and show the connection with the Ginibre ensemble of real non-symmetric random matrices. Numerical investigations of the spectral gap imply that a generic state of the system iterated several times by a fixed generic map converges exponentially to an invariant state

Space Vehicle Powerdown Philosophies Derived from the Space Shuttle Program

In spaceflight, electrical power is a vital but limited resource. Almost every spacecraft system, from avionics to life support systems, relies on electrical power. Since power can be limited by the generation system s performance, available consumables, solar array shading, or heat rejection capability, vehicle power management is a critical consideration in spacecraft design, mission planning, and real-time operations. The purpose of this paper is to capture the powerdown philosophies used during the Space Shuttle Program. This paper will discuss how electrical equipment is managed real-time to adjust the overall vehicle power level to ensure that systems and consumables will support changing mission objectives, as well as how electrical equipment is managed following system anomalies. We will focus on the power related impacts of anomalies in the generation systems, air and liquid cooling systems, and significant environmental events such as a fire, decrease in cabin pressure, or micrometeoroid debris strike. Additionally, considerations for executing powerdowns by crew action or by ground commands from Mission Control will be presented. General lessons learned from nearly 30 years of Space Shuttle powerdowns will be discussed, including an in depth case-study of STS-117. During this International Space Station (ISS) assembly mission, a failure of computers controlling the ISS guidance, navigation, and control system required that the Space Shuttle s maneuvering system be used to maintain attitude control. A powerdown was performed to save power generation consumables, thus extending the docked mission duration and allowing more time to resolve the issue