Three essays on financial intermediation

Financial intermediation plays a central role in connecting capital demanders, i. e. firms, and capital suppliers, i. e. investors. My essays focus on two types of financial intermediaries, namely investment banks, who provide a variety of services for firms and institutional investors, and sell-side security analysts, who analyze and provide information about firms, mainly, to institutional investors. The first essay studies security analysts’ cognitive biases in issuing earnings forecasts; the second essay studies analysts’ capital expenditure forecasts; and, the third essay studies the underwriting relationship value between investment banks and their client firms

Identification of machining defects by Small Displacement Torsor and form parameterization method

In the context of product quality, the methods that can be used to estimate machining defects and predict causes of these defects are one of the important factors of a manufacturing process. The two approaches that are presented in this article are used to determine the machining defects. The first approach uses the Small Displacement Torsor (SDT) concept [BM] to determine displacement dispersions (translations and rotations) of machined surfaces. The second one, which takes into account form errors of machined surface (i.e. twist, comber, undulation), uses a geometrical model based on the modal shape's properties, namely the form parameterization method [FS1]. A case study is then carried out to analyze the machining defects of a batch of machined parts

CSI-based versus RSS-based Secret-Key Generation under Correlated Eavesdropping

Physical-layer security (PLS) has the potential to strongly enhance the overall system security as an alternative to or in combination with conventional cryptographic primitives usually implemented at higher network layers. Secret-key generation relying on wireless channel reciprocity is an interesting solution as it can be efficiently implemented at the physical layer of emerging wireless communication networks, while providing information-theoretic security guarantees. In this paper, we investigate and compare the secret-key capacity based on the sampling of the entire complex channel state information (CSI) or only its envelope, the received signal strength (RSS). Moreover, as opposed to previous works, we take into account the fact that the eavesdropper's observations might be correlated and we consider the high signal-to-noise ratio (SNR) regime where we can find simple analytical expressions for the secret-key capacity. As already found in previous works, we find that RSS-based secret-key generation is heavily penalized as compared to CSI-based systems. At high SNR, we are able to precisely and simply quantify this penalty: a halved pre-log factor and a constant penalty of about 0.69 bit, which disappears as Eve's channel gets highly correlated

Construction des codes temps-espace en treillis équilibré pour nT antennes et modulation 4-PSK

National audienceCet article propose une nouvelle famille des codes temps-espace en treillis (STTC) pour plusieurs antennes d'émission et une modulation 4-PSK. On les appelle codes "équilibrés" car ils utilisent les points de la constellation MIMO d'une façon équiprobable. En comparant avec les autres codes publiés, on remarque que cette famille de codes fournit les meilleurs codes STTC. On peut alors limiter la recherche systématique des meilleurs codes seulement à cette famille de codes. L'article présente une méthode originale de construction des codes STTC équilibrés. Une liste complète des meilleurs codes à 4 états pour 2 antennes et plusieurs codes équilibrés à 16 états pour 2 et 3 antennes sont aussi donnés

4-PSK Balanced STTC with Two Transmit Antennas

International audienceIn this paper we introduce a new class of space-time trellis codes (STTC). We call them Balanced STTC (B-STTC) because the points of the constellation are used with the same probability. Comparing to known codes, the balanced codes offer the best performance. Therefore, the systematic search for good codes can be reduced to this class. We present here the design of the 4-PSK balanced STTC with 2 transmit antennas. A complete list of the best 4-state and several 16-state good balanced codes are also given

4-PSK Balanced STTC with Two Transmit Antennas

International audienceIn this paper we introduce a new class of space-time trellis codes (STTC). We call them Balanced STTC (B-STTC) because the points of the constellation are used with the same probability. Comparing to known codes, the balanced codes offer the best performance. Therefore, the systematic search for good codes can be reduced to this class. We present here the design of the 4-PSK balanced STTC with 2 transmit antennas. A complete list of the best 4-state and several 16-state good balanced codes are also given

A New Class of Balanced 4-PSK STTC for Two and Three Transmit Antennas

International audienceA new class of 4-PSK Space Time Trellis Codes (STTC) for 2 and 3 transmit antennas is proposed in this paper. We call these codes Balanced STTC because they use the points of the constellation with the same probability. Comparing to known codes, these codes offer the best performance. Therefore, the systematic search for good codes can be reduced to this class. It is shown that all the best published codes are balanced. The paper presents the design of these balanced STTC and gives a complete list of the best 4-state codes. Several 16-state balanced codes for 2 and 3 transmit antennas are also given

QPSK Balanced Space Time Trellis Codes

International audienceAll the best known space-time trellis codes (STTCs) belong to the Balanced STTCs class. The first method to design balanced STTCs is proposed in this letter. The exhaustive code search of optimal codes can then be reduced to this class. Finally, the proposed method is used to construct new QPSK codes for 3 and 4 transmit antennas which outperform the best previously published codes of the same complexity