KV. Cohomology and some applications

Two versions of the KV-cohomology are presented and some algebraic and geometrical applications are given. We will see some applications to stochastic manifold. As a consequence, we can apply these ideas in Lorentzian geometry, in particular in the theory of null hypersurfaces where it is defined a non Levi-Civitta connection as an auxiliary tool, and so, there is a stochastic structure.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Thermodynamic Conditions in Quenching Chamber of Low Voltage Circuit Breaker

Práce se zabývá studiem procesů probíhajících při zhášení silnoproudého oblouku ve zhášecí komoře jističe. Je zaměřena na výpočet dynamiky tekutin a teplotního pole v okolí elektrického oblouku. V práci je dále popsán vliv vzdálenosti plechů v komoře a vliv tvarů plechů z hlediska aerodynamických podmínek uvnitř komory. Dalším cílem dosaženým touto prací je poskytnutí informací o vlivu polohy elektrického oblouku na termodynamické vlastnosti uvnitř komory. Toto je důležité, zejména pokud je oblouk do komory vtahován jinými silami, např. elektromagnetickými a během tohoto vtahovacího procesu mění svůj tvar i polohu. Za účelem co nejjednoduššího, ale zároveň co nejefektivnějšího řešení úkolu, byl vyvinut software určen speciálně pro výpočet dynamiky tekutin numerickou metodou konečných objemů (FVM). Tato metoda je, v porovnání s rozšířenější metodou konečných prvků (FEM), vhodnější pro výpočet dynamiky tekutin (CFD) zejména proto, že režie na výpočet jedné iterace jsou menší v porovnání s ostatními numerickými metodami. Další výhodou tohoto softwarového řešení je jeho modularita a rozšiřitelnost. Cely koncept softwaru je postaven na tzv. zásuvných modulech. Díky tomuto řešení můžeme využít výpočtové jádro pro další numerické analýzy, např. strukturální, elektromagnetickou apod. Jediná potřeba pro úspěšné používání těchto analýz je napsáni solveru pro konečné prvky (FEM). Jelikož je software koncipován jako multi–thread aplikace, využívá výkon současných vícejádrových procesorů naplno. Tato vlastnost se ještě více projeví, pokud se výpočet přesune z CPU na GPU. Jelikož současné grafické karty vyšších tříd mají několik desítek až stovek výpočetních jader a pracují s mnohem rychlejšími pamětmi, než CPU, je výpočetní výkon několikanásobně vyšší.Work deals with the study of processes that attend the electric arc extinction inside the quenching chamber of a circuit breaker. It is focused on several areas. The first one is concerned to fluid dynamics calculations (CFD) and the second one is aimed at thermal field calculations. In this work effects of metal plates distance together with metal plates shapes are described from aerodynamical point of view. Another objective solved by this work is to give information about influence of an electric arc position in a quenching chamber, which changed its shape due to forces acting on it during extinction process. For purpose of this work a new software solution for CFD was developed. Whole software concept is based on plug-ins. Due to this solution, the software§s calculation core can be used for other numerical analyses, like structural, electromagnetic, etc. The only requirement is to write a plug-in for these analyses. Because the software is designed as multi-threaded application, it can use the fully performance of current multi-core processors. Above mentioned property can be especially shown off, when a calculation is moved from CPU to GPU (Graphics Processing Units). Current high-end graphic cards have tens to hundreds cores and work with faster memories than CPU. Due to this fact, the simulation performance can raised manifold.

Subsidy Competition and the Role of Firm Ownership

This paper addresses the role that foreign vs. domestic ownership of companies plays for governments in asymmetric countries' competition for a multinational's subsidiary. I argue that equilibrium subsidies as well as a foreign investor's location decision in policy competition between these countries critically depend on the ownership structure of incumbent firms. This shows that small countries with few national incumbents in an industry may be successful in attracting multinationals

A Note on the Manickam-Mikl\'os-Singhi Conjecture for Vector Spaces

Let $V$ be an $n$-dimensional vector space over a finite field $\mathbb{F}_q$. Define a real-valued weight function on the $1$-dimensional vector spaces of $V$ such that the sum of all weights is zero. Let the weight of a subspace $S$ be the sum of the weights of the $1$-dimensional subspaces contained in $S$. In 1988 Manickam and Singhi conjectured that if $n \geq 4k$, then the number of $k$-dimensional subspaces with nonnegative weight is at least the number of $k$-dimensional subspaces on a fixed $1$-dimensional subspace. Recently, Chowdhury, Huang, Sarkis, Shahriari, and Sudakov proved the conjecture of Manickam and Singhi for $n \geq 3k$. We modify the technique used by Chowdhury et al. to prove the conjecture for $n \geq 2k$ if $q$ is large. Furthermore, if equality holds and $n \geq 2k+1$, then the set of $k$-dimensional subspaces with nonnegative weight is the set of all $k$-dimensional subspaces on a fixed $1$-dimensional subspace.Comment: 15 pages; this version fixes typos and some minor mistakes, also some proofs got a bit more explicit for an easier understandin

Bargaining under Incomplete Information, Fairness, and the Hold-Up Problem

In the hold-up problem incomplete contracts cause the proceeds of relation specific investments to be allocated by ex-post bargaining. The present paper investigates the efficiency of incomplete contracts if individuals have heterogeneous preferences implying heterogeneous bargaining behavior and - equally important - preferences are private information. As the sunk investment costs can thus potentially signal preferences, they can influence beliefs and consequently bargaining outcomes. The necessities of signalling are shown to generate very strong investment incentives. These incentives are based on the desire not to reveal information that is unfavorable in the ensuing bargaining. After finding all perfect Bayesian equilibria in pure strategies, the paper derives the necessary and sufficient conditions under which it is optimal to invest and trade efficiently

Animating the Archive: The trial and testimony of a Sufi saint

In 1895 the colonial administration of Senegal sentenced Sheikh Amadu Bamba to exile for stirring anti-colonial disobedience. At his trial, Bamba allegedly recited a prayer in defiance of the French authorities. Although there is no archival record to prove that the prayer was recited, since the 1970s Bamba's disciples have flocked to the former seat of colonial power to commemorate his act of resistance; their testimony has displaced the authority of the colonial archive and imagines a decolonial utopia in archival absence. This article examines how their prayer subverts the colonial archive, while it remains entangled in its substrate

Fairness, Adverse Selection, and Employment Contracts

This paper considers a firm whose potential employees have private information on both their productivity and the extent of their fairness concerns. Fairness is modelled as inequity aversion, where fair-minded workers suffer if their colleagues get more income net of production costs. Screening workers with equal productivity but different fairness concerns is shown to be impossible if both types are to be employed, thereby rendering the optimal employment contracts discontinuous in the fraction of fair-minded workers. As a result, fairness might infuence the employment contracts of all workers although only some are fair-minded, and identical firms facing very similar pools of workers might employ very different remuneration schemes