Wind loads analysis at the anchorages of the Talavera de la Reina cable stayed bridge

This paper describes wind tunnel tests performed on wind tunnel models of the Talavera de la Reina cable stayed bridge. The work describes the aeroelastic model construction and it is focused on the evaluation and analysis of the mean and peak wind loads at the tower foundation and the cable anchorages since these data can be very useful by the bridge manufacturer as a support for the bridge design. The work is part of a complete wind tunnel study carried out to analyze the aeroelastic stability of the bridge

Mechanisms for analysis and detection of ransomware in desktop operating systems

Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do ParanáRansomware attacks have become a danger to computer systems, leading to data loss, monetary losses, and business interruptions. We propose a machine learning-based method for ransomware detection on Linux to identify these attacks. To detect ransomware activity on the system, our approach combines the file system with a predictive model. To obtain sufficient infection information we use the data from the alteration calls to the files on the file system. This data is then fed into a machine-learning algorithm. Using a dataset we collected from uninfected files and files infected with various types of ransomware and were able to achieve a high detection rate with a low false positive rate. Our methodology can be incorporated into current security programs to improve detection and defense against ransomware attacks in the Linux environment.Os ataques de ransomware se tornaram um perigo para os sistemas de computador, levando à perda de dados, perdas monetárias e interrupções nos negócios. Propomos um método baseado em aprendizado de máquina para detecção de ransomware no Linux para identificar esses ataques. Para detectar a atividade de ransomware no sistema, nossa abordagem combina o sistema de arquivos com um modelo preditivo. Para obter informações suficientes sobre a infecção, usamos os dados das chamadas de alteração dos arquivos no sistema de arquivos. Esses dados são então inseridos em um algoritmo de aprendizado de máquina. Usando um conjunto de dados que coletamos de arquivos não infectados e arquivos infectados com vários tipos de ransomware, conseguimos atingir uma alta taxa de detecção com uma baixa taxa de falsos positivos. Esta metodologia pode ser incorporada nos programas de segurança atuais para melhorar a detecção e a defesa contra ataques de ransomware no ambiente Linux

Study of the Effect of Water Depth on Potential Flow Solution of the OC4 Semisubmersible Floating Offshore Wind Turbine

AbstractThis work aims at assessing the influence of water depth on the potential flow solution for a semisubersible floating offshore wind turbine. More specifically, the system developed for the Offshore Code Comparison Collaboration Continuation (OC4) of the Inter- national Energy Agency IEA was considered for this paper. This work has been inspired by previous studies concerning the effect of shallow water on Liquified Natural Gas Carriers (LNGC). The influence of water depth on the hydrodynamics of such systems is evident from measurements as well as from simulations, specifically when secondary effects in the wave and flow modelling are addressed. This scenario has motivated the comparative study for the Floating Wind Turbine herein reported, also taking into account second order hydrodynamics (Quadratic Transfer Functions, QTF) as well as low frequency contribution in the incoming wave, due to shallow water (Setdown effect). The simulations were conducted relying on the codes DIFFRAC and aNySIM, de- veloped at Maritime Research Institute of Netherlands (MARIN) and the results are presented for a range of water depth between the nominal value of 200 m and the extreme shallow water of 30 m

Full scale monitoring of the twin chimneys of the rovinari power plant

The presented paper deals with the structural identification and monitoring of two twin chimneys in very close arrangement. Due to twin arrangement, important interference effects are expected to modify the chimney response to wind action, causing vortex shedding and state-dependent excitation associated to the oscillatory motion of the leeward chimney, in and out of the windward chimney wake. The complexity of the physics of this problem is increased by the dependency of the aerodynamics of circular cylinders on Reynolds number; however, there is a weakness of literature about cylinders behaviour at critical and super-critical range of Reynolds number, due to experimental limitations. Also the International Committee on Industrial Chimneys (CICIND) does not provide, at present, any specific technical guideline about twin chimneys whose interaxis distance is less or equal two times the diameter, as in this case. For this reason a Tuned Mass Damper (TMD) has been installed in order to increase the damping of the chimney, as merely suggested. This work aims at assessing the effectiveness of the installed TMD and characterizing the tower dynamic behaviour itself due to the wind excitation, as well as providing full scale measurements for twin cylinders configuration at high Reynolds numbers

Adding aerodynamic damping: the wing design for the Third Bosphorus Bridge

This paper is about the design of wing profiles adequate for giving to the Third Bosphorus Brige an additional aerodynamic damping on both vertical bending as well as torsional modes. The additional damping estimate procedure is made through a simplified quasi steady approach. A CFD approach has been used for a preliminary design and optimization of the wing profile and its position over the wind screen at the upwind and downwind location

Wind tunnel validation of AeroDyn within LIFES50+ project: Imposed Surge and Pitch tests

This paper presents the first set of results of the steady and unsteady wind tunnel tests, performed at Politecnico di Milano wind tunnel, on a 1/75 rigid scale model of the DTU 10 MW wind turbine, within the LIFES50+ project. The aim of these tests is the validation of the open source code AeroDyn developed at NREL. Numerical and experimental steady results are compared in terms of thrust and torque coefficients, showing good agreement, as well as for unsteady measurements gathered with a 2 degree-of-freedom test rig, capable of imposing the displacements at the base of the model, and providing the surge and pitch motion of the floating offshore wind turbine (FOWT) scale model. The measurements of the unsteady test configuration are compared with AeroDyn/Dynin module results, implementing the generalized dynamic wake (GDW) model. Numerical and experimental comparison showed similar behaviours in terms of non linear hysteresis, however some discrepancies are herein reported and need further data analysis and interpretations about the aerodynamic integral quantities, with a special attention to the physics of the unsteady phenomenon