The effect of credit rating changes on firms’ leverage : US firms between 2009 and 2017

This dissertation examines the effect of a change in credit rating on firm’s Leverage decisions. I find that firms tend to undertake strong capital market activities immediately after the 2008 financial crisis, by reducing their issuance of debt in the aftermath of a downgrade. I also find that firms with higher credit ratings have less debt and more equity when compared to firms that have lower credit ratings. Firms issue approximately less 3 percentage points of debt following a downgrade, whereas upgraded firms issue more debt, following the change in their credit rating.Esta dissertação examina o efeito de uma mudança na classificação de crédito nas decisões de Alavancagem da empresa. Acho que as empresas tenderam a realizar fortes atividades no mercado de capitais imediatamente após a crise financeira de 2008, reduzindo sua dívida de emissão. Também descobri que as empresas com classificações de crédito mais altas têm menos dívida e mais patrimônio quando comparadas às empresas com classificações de crédito mais baixas. Os rebaixamentos têm efeito negativo na emissão de dívida da empresa, as empresas emitem aproximadamente menos 3 pontos percentuais de dívida após um rebaixamento, enquanto as empresas atualizadas emitem mais dívida, após a mudança em sua classificação de crédito

Understanding the durability of advanced fibre-reinforced polymer (FRP) composites for structural applications

Fibre-reinforced polymer (FRP) composites are increasingly being used in the field of civil engineering, either for the rehabilitation/retrofitting of existing infrastructures or for the construction of new structural elements. However, such applications are still recent and there are still unresolved questions regarding the long-term durability of FRP reinforcements or structural elements under service conditions, and their behaviour under accidental fire events as well. In this chapter, it is proposed to highlight the basic mechanisms involved in the environmental degradation of FRP composites, with a large emphasis on ageing mechanisms of the polymer matrix and their consequences on the mechanical properties. The last section is specifically devoted to the fire behaviour of polymer composites and also recalls existing fire-proofing solutions

Identification de zones pluviométriques homogènes d’un bassin versant à partir de l’information topographique

La recherche de zones pluviométriques homogènes sur la base des informations issues de la topographie consiste à subdiviser un bassin versant en zones climatiques homogènes. Ces régions sont identifiées en intégrant une information externe en bonne corrélation avec la pluviométrie, à savoir le relief. Le climat étant caractérisé par la moyenne et l’écart‑type des séries mensuelles pluviométriques, une relation entre ces statistiques et les variables explicatives reliées à la topographie est établie sous la forme d’une régression linéaire multiple. Ces variables constituent des attributs topographiques, qui servent de support à une classification du bassin versant en zones homogènes, pouvant être une étape préliminaire à un travail d’optimisation de réseaux pluviométriques.The identification of homogeneous rainfall zones, on the basis of topographic information, consists of subdividing the area of a watershed into homogeneous climate zones. These regions are identified by integrating external information that is well correlated with rainfall, namely the relief. The climate is characterized by the average and standard deviation of monthly rainfall. In the present study, a relationship between these statistics and explanatory variables linked to the topography, was modelled using multiple linear regression. These variables constitute topographic attributes that are adopted as support for the classification of watersheds into homogeneous zones and may be the preliminary step in the optimisation of rainfall networks

Thermal simulation using BIM a case study: Tunisian traditional dwelling

Traditional architecture is adapted to the cultural and climatic environment. It was able to respond to the conditions of minimal comfort of its inhabitants. This architecture contains centuries of knowledge to encourage researchers to make out its secret and evaluate its energy efficiency. In Tunisian context, pioneering work analysis concerning traditional houses, have shown that comfort conditions were acceptable during the hot season and mediocre during the cold season. Other studies have shown that this kind of architecture was able to respond to winter and summer climate requirements, but especially in the summer period, in coherence with the lifestyle of residents. Several study models concerning the thermal behavior of buildings are found in the literature. These models use software for simulating stationary regime or transient. Each program has its own interface and its own modeling engine, calculation and analysis, as TRNSYS (Transient System Simulation Tool) and EnergyPlus. For the simulation, we opted for sustainable software that allows architects and engineers to collaborate and interoperate more efficiently based on workflow and project requirements. The use solution is the BIM (Building Information Modeling) of Autodesk Revit that allows coordination throughout the design project. Our paper examines the effectiveness of promising new technology BIM in the thermal simulation of traditional Tunisian architecture bioclimatic. Research has showed the importance of BIM technology in the workflow and is efficiency to determine the energy performance of buildings with passive design and to evaluate their energy consumption. Revit gives interesting results for the standard contemporary home. As far as it knows, there are no studies on the traditional bioclimatic house or vernacular character using BIM technology for simulate this type of habitat. In this paper, we propose to use Revit to study the thermal behavior of the Tunisian traditional home.Peer ReviewedPostprint (published version

Creep behavior of cold-curing epoxy adhesives: analysis and predictive approach

Composites In Civil Engineering (CICE), VANCOUVER, CANADA, 20-/08/2014 - 22/08/2014Creep behavior of cold-curing epoxy adhesives: analysis and predictive approach This study investigates the creep behavior of two commercially available cold-curing epoxy adhesives, intended for the bonding of external composite reinforcements on concrete structures. In a preliminary stage, the characteristics of the mineral fillers (nature, content and size) contained in the two systems were determined, and the viscoelastic properties of the unfilled epoxy matrices extracted from these systems were analyzed. Short-term tensile creep experiments were then carried-out on cured samples of the two adhesives and their unfilled matrices, in order to evaluate the influence of the fillers and the polymer network characteristics on the instantaneous and delayed mechanical responses. Finally, two predictive approaches based on either the Time-Temperature Superposition Principle (TTSP) or the Time-Stress Superposition Principle (TSSP) were applied to evaluate the long-term creep behavior, and their suitability in the case of cold-curing adhesives was discussed

Impact on survival of nuclear atypia in epithelioid malignant mesothelioma

Introduction: Malignant pleural mesothelioma is a rare tumour with a bad prognosis. The only consensual prognostic factorsare represented by the stage and the histologic type. Concerning the histologic type, epithelioid mesothelioma is known to havebetter prognosis in comparison with the sarcomatoid and biphasic types. Epithelioid mesotheliomas have been reported to bea heterogeneous prognostic group. Our aim was to assess the impact on the survival of different characteristics of epithelioidmesothelioma, including nuclear atypia, mitotic count, MIB-1 index, inflammatory host response, stromal desmoplasia, necrosis,vascular emboli and invasion depth. Material and methods: We performed a study of survival of 30 malignant pleural mesotheliomas according to the differentparameters studied. Results: The study included 26 women and 4 men. The mean age of the patients was 61 years. The microscopic exam concludedto an epithelioid mesothelioma in 17 cases, sarcomatoid mesothelioma in 4 cases and biphasic mesothelioma in 9 cases. The 17cases of epithelioid mesothelioma developed severe nuclear atypia in 6 cases and mild nuclear atypia in 11 cases. The mitoticcount and the MIB-1 score were respectively inferior to 5 mitoses/50 HPF and inferior to 10% in 11 cases and were superior to5 mitoses/50 HPF and superior to 10% in 6 cases. No vascular emboli were recorded. Tumour necrosis was reported in 1 case.The inflammatory host response was severe in 4 cases and mild in 13 cases. The tumoral stroma was desmoplastic in 4 cases.The invasion depth was superior to 0.5mm in 16 cases. The median overall survival amounted to 180 days. Nuclear atypia wasthe only feature that had impact on survival in the group of epithelioid mesothelioma. Conclusion: Our results highlight the correlation of nuclear atypia with survival

4x4 Time-Domain MIMO encoder with OFDM Scheme in WIMAX Context

The Standard Worldwide Interoperability for Microwave Access (WiMAX) offers the opportunity to develop applications that require more bandwidth and increased communication up to 50 km. Through literature reviews, the coding block is done in the frequency domain of the OFDM chain in a wireless communication system. This solution offers outstanding performance within the meaning of binary error rate and throughput. We propose to design a Simulink model of 4x4 OFDM transmission chain for WIMAX context and using a coding block in the temporal domain to test system performance and compare it to the one used in the frequency domain .We use the IEEE 802.16 standard [1] for the construction of the OFDM symbol, the generation of the preamble and the choice of the cyclic prefix length. Our choice is situated to test the performances of the system when the coding block is in the temporal domain. Our simulated chain offers a slightly better performance than the chain where the MIMO encoder is located in the frequency domain. This approach provides the ability to expand the number of transmitting antennas without revising all of the calculations