Electrical and Magnetical Modeling of Inductive Coupled Power Transfer Systems

Nowadays, there is a very high number of electronic devices with different ranges of power. Desktop peripherals and cellphones are an example of widely used low power devices. Contactless power transfer is useful to supply or recharge these devices without any physical link. Their lifetime can be increased because wires are a source of dysfunction. Contactless power transfer is also very useful in supplying rotating parts. Indeed, the brushes typically used for this purpose are impractical for high speed applications and are also a source of dysfunction. In recent years, the development of electric vehicles became a great opportunity for contactless power transfer applications. The batteries of these vehicles have a limited autonomy which makes the charging process very important. By taking as a starting point, the contactless battery charging for an electric vehicle, this work addresses contactless power transfer using inductive couplers. The modelling proposed in the scope of this work is available for different ranges of power. However, special attention is given to crucial points for high power applications, which are the efficiency of the system and the radiated magnetic field. Indeed, the efficiency in high power transfer is a crucial point for ecological and thermal dissipation reasons. The radiated field must be limited to meet magnetic radiation guidelines and to ensure the safety of users. The inductive coupled power transfer (ICPT), similar to a conventional transformer, is made of two magnetically coupled coils. The first one, called the primary coil, is supplied with an alternating current, which induces a voltage in the secondary coil. The amplitude of the induced voltage in the secondary coil is a function of the magnetic coupling factor and the operating frequency. The main difference between conventional transformers and inductive couplers is the value of the magnetic coupling. Indeed, the distance between the coils is larger for inductive couplers, and the magnetic field lines are not guided by a ferromagnetic material as in the case in conventional transformers. As a result, such a system is also called an "air-transformer". To obtain high performance in spite of a very low coupling factor (typically $0.1$ compared to $0.9$), compensation capacitances are inserted into the system. They compensate the very low power factor due to the magnetisation of the inductances. The different compensation topologies are studied and compared in detail in this work. They determine the load characteristic, the frequency response and the values of the voltages and currents in the coils. A novel compensation methodology is proposed and compared to the existing one. It aims to simplify the transformer's control instead of maximizing the efficiency. When a conductive plate is close to the transformer, Eddy currents are induced leading to the generation of Joule losses. The system efficiency is thus decreased and thermal dissipation becomes an issue. In this case, adding magnetic shielding to the structure is very efficient. A modelling of these effects is performed and several shielding topologies are proposed. An optimisation of the shielding geometry, based on genetic algorithms, is also undertaken

Tropical summer induces DNA fragmentation in boar spermatozoa: implications for evaluating seasonal infertility

Summer infertility continues to undermine pig productivity, costing the pig industry millions in annual losses. The boar’s inefficient capacity to sweat, non-pendulous scrotum and the extensive use of European breeds in tropical conditions, can make the boar particularly vulnerable to the effects of heat stress; however, the link between summer heat stress and boar sperm DNA damage has not yet been demonstrated. Semen from five Large White boars was collected and evaluated during the early dry, late dry and peak wet seasons to determine the effect of seasonal heat stress on the quality and DNA integrity of boar spermatozoa. DNA damage in spermatozoa during the peak wet was 16-fold greater than during the early dry and nearly 9-fold greater than during the late dry season. Sperm concentration was 1.6-fold lower in the peak wet than early dry whereas no difference was found across several motility parameters as determined by computer-assisted sperm analysis. These results demonstrate that tropical summer (peak wet season) induces DNA damage and reduces concentration without depressing motility in boar spermatozoa, suggesting that traditional methods of evaluating sperm motility may not detect inherently compromised spermatozoa. Boar management strategies (such as antioxidant supplementation) need to be developed to specifically mitigate this problem

Global distributions and strain diversity of avian infectious bronchitis virus: a review

The poultry industry faces challenge amidst global food security crisis. Infectious bronchitis is one of the most important viral infections that cause huge economic loss to the poultry industry worldwide. The causative agent, infectious bronchitis virus (IBV) is an RNA virus with great ability for mutation and recombination; thus, capable of generating new virus strains that are difficult to control. There are many IBV strains found worldwide, including the Massachusetts, 4/91, D274, and QX-like strains that can be grouped under the classic or variant serotypes. Currently, information on the epidemiology, strain diversity, and global distribution of IBV has not been comprehensively reported. This review is an update of current knowledge on the distribution, genetic relationship, and diversity of the IBV strains found worldwide

Les lymphomes B ALK positifs (une nouvelle entité parmi les lymphomes B diffus à grandes cellules)

TOULOUSE3-BU Santé-Centrale (315552105) / SudocTOULOUSE3-BU Santé-Allées (315552109) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Recherches sur la syntaxe en milieu sous-prolétaire

Auvigne Marie-Agnès, Monte Michèle. Recherches sur la syntaxe en milieu sous-prolétaire. In: Langage et société, n°19, 1982. pp. 23-63