Islamic Private Equity

The Islamic private equity (IPE) market has grown dramatically over the last few years. There are some similarities between venture capital (VC) and some traditional methods in Islamic financing. In medieval Islamic societies it is hard to pinpoint the starting of IPE but there were partnership arrangements similar to those practiced in conventional private equity (PE). But both academicians and professionals argue that the VC activity started in 1946 when General Doriot, a French born and a Harvard educated businessman, established the American Research and Development Corporation (ARDC). It grew in Silicon Valley in the 1970s. Intel and Microsoft are amongst the most famous projects financed through VC. Without the intervention of venture capitalists none of these would have seen light of day or at least achieved such a spectacular rate of development in such a short period (Queyrel, 2006).Islamic Finance, Islamic banks, Shari'ah compliance

Running-in wear modeling of honed surface for combustion engine cylinder liners

The texture change during running-in alters the performance and efficiency of a tribo-mechanical system. During mass production of cylinder liners, a final finishing stage known as ‘‘plateau honing’’ is commonly added to reduce the running-in wear process of the liner surface. The majority of researchers think that this operation improves the engine efficiency and decreases oil consumption. It was believed that there are close links between the surface topography of honed cylinders change and their wear resistance during running-in. However, these interactions have not yet been established. Some running-in wear models were developed in the open literature to predict topographical surface changes without considering the running-in conditions. The present paper thus investigates the various aspects of the wear modeling that caused running- in problems in honed surfaces and its implications on ring-pack friction performance. To illustrate this, plateau honing experiments under different conditions were first carried out on an instrumented vertical honing machine. The plateau honing experiments characterize the surface modifications during running-in wear of cast-iron engine bores using advanced characterization method. Based on the experimental evidence, a running-in wear model was developed. Finally, a numerical extension of the developed model was applied to solve the Reynolds equation by taking into account the real surface topographies of the engine bore. This enables us to predict realistic friction performance within the cylinder ring-pack tribosystem

Mutual influence of cross hatch angle and superficial roughness of honed surfaces on friction in ring-pack tribo-system

The cylinder bore surface texture, widely produced by the honing technique, is an essential factor for a good engine performance (friction, oil consumption, running-in, wear etc.). This explains the improvement and development of various new honing techniques. These different honing processes generate surfaces with various texture features characteristics (roughness, valleys depth, cross hatch angle, etc.). This paper addresses a comparison of ring-pack friction for cylinder surfaces produced by plateau honing and helical slide honing. It takes in consideration the mutual effect of superficial plateau roughness amplitude and honing angle. A numerical model is developed to predict friction within the cylinder ring-pack system in mixed lubrication regime. The results show the effectiveness of helical slide honed surface texture in comparison to plateau honed bore surface

Blow-up and lifespan estimate for the generalized tricomi equation with the scale-invariant damping and time derivative nonlinearity on exterior domain

The article is devoted to investigating the initial boundary value problem for the damped wave equation in the scale-invariant case with time-dependent speed of propagation on the exterior domain. By presenting suitable multipliers and applying the test-function technique, we study the blow-up and the lifespan of the solutions to the problem with derivative-type nonlinearity $ \d u_{tt}-t^{2m}\Delta u+\frac{\mu}{t}u_t=|u_t|^p, \quad \mbox{in}\ \Omega^{c}\times[1,\infty), $ that we associate with appropriate small initial data

La dialéctica jurídica y política entre la ley de importación argelina y la legislación de la OMC (Organización Mundial de Comercio)

La economía internacional ha definido cambios radicales en las economías proteccionistas a los regímenes económicos y comerciales libres bajo la Organización Mundial del Comercio, que requiere que los países que desean unirse a ellos cambien sus políticas económicas y comerciales de acuerdo con Principios del sistema de comercio internacional basado en el libre comercio. La adopción de una política de economía de mercado y la adhesión a la Organización, pero introdujo algunas leyes que contradicen los principios del libre comercio como el derecho de importación y las nuevas licencias de importación basadas en Restricciones cuantitativas a las importaciones

Islamic Private Equity

The Islamic private equity (IPE) market has grown dramatically over the last few years. There are some similarities between venture capital (VC) and some traditional methods in Islamic financing. In medieval Islamic societies it is hard to pinpoint the starting of IPE but there were partnership arrangements similar to those practiced in conventional private equity (PE). But both academicians and professionals argue that the VC activity started in 1946 when General Doriot, a French born and a Harvard educated businessman, established the American Research and Development Corporation (ARDC). It grew in Silicon Valley in the 1970s. Intel and Microsoft are amongst the most famous projects financed through VC. Without the intervention of venture capitalists none of these would have seen light of day or at least achieved such a spectacular rate of development in such a short period (Queyrel, 2006)

Islamic Private Equity

The Islamic private equity (IPE) market has grown dramatically over the last few years. There are some similarities between venture capital (VC) and some traditional methods in Islamic financing. In medieval Islamic societies it is hard to pinpoint the starting of IPE but there were partnership arrangements similar to those practiced in conventional private equity (PE). But both academicians and professionals argue that the VC activity started in 1946 when General Doriot, a French born and a Harvard educated businessman, established the American Research and Development Corporation (ARDC). It grew in Silicon Valley in the 1970s. Intel and Microsoft are amongst the most famous projects financed through VC. Without the intervention of venture capitalists none of these would have seen light of day or at least achieved such a spectacular rate of development in such a short period (Queyrel, 2006)

Code-based Identification and Signature Schemes

In an age of explosive growth of digital communications and electronic data storage, cryptography plays an integral role in our society. Some examples of daily use of cryptography are software updates, e-banking, electronic commerce, ATM cards, etc. The security of most currently used cryptosystems relies on the hardness of the factorization and discrete logarithm problems. However, in 1994 Peter Shor discovered polynomial-time algorithms for prime factorization and discrete logarithms on a quantum computer. Therefore, it is of extreme importance to develop cryptosystems that remain secure even when the adversary has access to a quantum computer; such systems are called post-quantum cryptosystems. One promising candidate is based on codes; in this thesis we focus more specifically on code-based identification and signature schemes. Public key identification schemes are typically applied in cryptography to reach the goal of entity authentication. Their applications include authentication and access control services such as remote login, credit card purchases and many others. One of the most well-known systems of this kind is the zero-knowledge identification scheme introduced in Crypto 1993 by Stern. It is very fast compared to schemes based on number-theoretic problems since it involves only simple and efficiently executable operations. However, its main drawbacks are the high communication complexity and the large public key size, that makes it impractical for many applications. Our first contribution addresses these drawbacks by taking a step towards reducing communication complexity and public key size simultaneously. To this end, we propose a novel zero-knowledge five-pass identification scheme which improves on Stern's scheme. It reduces the communication complexity by a factor of 25 % compared to Stern's one. Moreover, we obtain a public key of size of 4 KB, whereas Stern's scheme requires 15 KB for the same level of security. To the best of our knowledge, there is no code-based identification scheme with better performance than our proposal using random codes. Our second contribution consists of extending one of the most important paradigms in cryptography, namely the one by Fiat and Shamir. In doing so, we enlarge the class of identification schemes to which the Fiat-Shamir transform can be applied. Additionally, we put forward a generic methodology for proving the security of signature schemes derived from this class of identification schemes. We exemplify our extended paradigm and derive a provably secure signature scheme based on our proposed five-pass identification scheme. In order to contribute to the development of post-quantum schemes with additional features, we present an improved code-based threshold ring signature scheme using our two previous results. Our proposal has a shorter signature length and a smaller public-key size compared to Aguilar et al.'s scheme, which is the reference in this area