André Seidel

Tax Evasion, Corruption and Market Entry

We analyze the impact of tax policy on the market entry of firms in the presence of corruption and tax evasion. In a world with corruption, firms must bribe corrupt officials to enter the market. For a given level of bribes, higher tax rates and stricter enforcement of taxation decrease tax evasion but typically reduce market entry. However, when the level of bribes reacts to tax policy, higher taxes and stricter enforcement of taxation can have a double benefit. Up to a certain threshold, for which we develop a simple rule, stricter enforcement increases market entry and reduces tax evasion.

Aspects of Creep Behavior of Textile Reinforcements for Composite Materials~!2009-03-04~!2009-10-15~!2009-12-11~!

Numerous technical applications utilize fiber reinforced composites made with high performance glass and/or carbon fibers. These fibers are especially desirable due to their mechanical and chemical properties resulting in high tensile strength. A relatively new application field is textile reinforced concrete (TRC), which is composed of a textile structure made up of multifilament yarns (rovings) and a cement matrix. To guarantee that the fibers retain their strength over long periods of time in an alkaline milieu, alkaline resistant materials such as alkali-resistant glass fibers (AR-glass) are used. Further requirements placed on textile reinforcements include excellent mechanical properties, such as high strength and stiffness, which remain unchanged or are nominally altered under long-term stresses. These properties will be discussed in this paper within the framework of an experiment conducted, which observed the behavior of AR-glass rovings under continuous long-term stress relative to time. The paper analyzes and interprets the results obtained on the yarns’ mechanical properties. The objective was to develop a mechanical model of the material behavior of the textile structures to aid in the prognosis of long-term behavior of textile reinforced composite materials (i.e. textile reinforced concrete).

Study of tensile behavior for high-performance fiber materials under high-temperature loads

Textile high-performance filament yarn subjected to extremely high thermal loads can be found in various technical application fields. Besides the mechanical loads, textile fiber materials have to also satisfy high safety requirements in these applications with respect to thermal loads. Some of the main fields of application in the field of mechanical engineering are turbines, drive devices, rocket components and fire protection coatings. Textile grid-like structures are also being increasingly used in civil engineering as reinforcements (textile concretes). The design and development of textile structures for these applications demands studying and acquiring the material behavior under high thermal loads. Neither sufficient data nor standardized testing methods have been extensively achieved for evaluating the tensile characteristics of filament yarns under thermal influences. Hence, studying the thermal behavior of these yarns, which are used as input material for the reinforcing structures, is essential. The impact of the standard atmospheric condition on the oxidation behavior of the yarns, as in the case of carbon filament yarns and their influence on the physicochemical and tensile mechanical properties, have to be studied as well. This paper aims to address this issue and provides an insight into the current research about the development and realization of a novel test stand and the subsequent study of tensile mechanical behavior for textile high-performance fiber material under extreme thermal loads together with their physicochemical behavior.

Stress-strain behavior of carbon filament yarns under high strain rates

Fiber-reinforced composites used in numerous technical applications have to meet the ever increasing safety requirements. Resistance to extreme stress under high velocity impact loads assumes even greater significance. Previous studies on the behavior of fiber-reinforced composites under impact loads provide little insight about the properties of filament yarns, a basis for many composite applications. Hence this paper focuses on the development of a suitable test method for performing high speed tensile tests on all filament yarn types, and the acquisition and analysis of the test results. This will enable the derivation of material models for their usage in the field of composites applications. Initially, the widely used carbon fiber filament yarns have been tested. The conclusive test results with a reduced yarn clamp mass and high stiffness of the test apparatus indicate that tensile strength and modulus of elasticity of carbon filament yarns increase with higher strain rates.

Tax Evasion, Corruption and Tax Loopholes

Abstract This paper addresses tax loopholes that allow firms to exploit borderline cases between legal tax avoidance and illegal tax evasion. In general, tax loopholes are detrimental to a revenue-maximizing government. This may change in the presence of corruption in the tax administration. Tax loopholes may serve as a separating mechanism that helps governments maximize revenues and curb corruption, which may explain why developing countries only gradually close loopholes in their tax codes.