Floods through inundated urban environments constitute a hazard to the population andinfrastructure. A series of field measurements were performed in an inundated section ofthe City of Brisbane (Australia) during a major flood in January 2011. Using an acousticDoppler velocimeter (ADV), detailed velocity and suspended sediment concentrationmeasurements were conducted about the peak of the flood. The results are discussed with afocus on the safety of individuals in floodwaters and the sediment deposition during theflood recession. The force of the floodwaters in Gardens Point Road was deemed unsafe forindividual evacuation. A comparison with past laboratory results suggested that previousrecommendations could be inappropriate and unsafe in real flood flows.

The stability properties of the rotating free surface flow in a cylindrical container isstudied using a global stability approach, considering successively three models. For thecase of solid body rotation (Newton’s bucket), all eigenmodes are found to be stable, andare classified into three families: gravity waves, singular inertial modes, and Rossbywaves. For the case of a potential flow, an instability is found. The mechanism isexplained as a resonance between gravity waves and centrifugal waves, and is thought to beat the origin of the “rotating polygon instability” observed in experiments where the flowis driven by rotation of the bottom plate (see L. Tophøj, J. Mougel, T. Bohr, D. Fabre,The Rotating Polygon Instability of a Swirling Free Surface Flow, Phys. Rev. Lett. 110(2013) 194502). Finally, in the case of the Rankine vortex which in fact consists in thecombination of the two first cases, we report a new instability mechanism involving Rossbyand gravity waves.

Sustainability is one of the challenging issues in electricity production systems.Recently, solid oxide fuel cell (SOFC) has been suggested for use in combined heat andpower (CHP) systems. This application is introduced as a promisingenvironmentally-friendly system according to the thermodynamic and electrochemical models.In this paper, an atmospheric SOFC/CHP cycle was analysed based on integrating exergyconcepts, energy and mass balance equations. In this regard, a zero-dimensional energy andmass balance model was developed in engineering equation solver (EES) software. Twodimensionless parameters (the exergetic performance coefficient (EPC) for investigatingthe whole cycle, and exergetic efficiency for investigating the exergy efficiency of themain component of this cycle) were applied. Results show that efficiencies of the systemhave been increased substantially. The electrical efficiency, total efficiency and EPC ofthis cycle were ~54%,~79% and~58% respectively.Moreover, the CO2emission is 19% lower than when compared with a conventional combined power cycle fed bynatural gas. In addition, a dynamic economic evaluation was performed to extract the mostsensitive parameters affecting the outputs: electricity sales price (ESP), equipmentpurchase cost and fuel cost. Furthermore, an electricity production cost of~125 $MW.h-1 wasattributed to our model, resulting in yet further cost reduction for widespreadapplications of this cycle.

Showerhead cooling process which consists of internal convective cooling and externalfilm cooling of a turbine blade is investigated using ANSYS-CFX software. The aim of thepresent investigation is to provide a better understanding of the fundamental nature ofshowerhead cooling using the three dimensional Reynolds averaged Navier Stokes analysis. Anumerical model has been developed to study the effects of coupled internal and externalcooling of the leading edge for a semi-elliptical body shape with the SST k-ω model. This modelconsists of all internal flow passages and cooling hole rows at the leading edge. Thenumerical results obtained are discussed and compared with experimental data available inthe literature. The results show that the cooling efficiency increases with the increaseof the blowing ratio and the Mach number, therefore, the overall efficiency for the steelbecomes less important compared to the plexiglas which has a low thermal conductivity.

The finite element analysis of the behaviour of airframes subjected to crash or impactloadings requires the use of suitable finite elements, in particular for the modelling ofriveted assemblies. In order to predict the structure survivability, it is indeednecessary to focus on these areas because stress concentrations, and consequently crackinitiations, which can lead to catastrophic loss of the airplane, are likely to occur.Because of the local nature of the phenomenon, the disproportion between the aircraft andthe assembly scale, and the large number of fasteners in a complete structure (more than100 000), super-elements for the fasteners and for the perforated sheets have beendeveloped in order to suitably model assemblies in structural calculations. However, thesetwo types of finite elements can not be currently connected together. The paper presentedhere focuses on how to link these finite elements.

This paper presents closed loop simulation of a CMOS-MEMS force sensor for biomedicalapplications employing an optimal proportional-integral-derivative controller. Since thedynamic behavior of the sensor under investigation is nonlinear the iterative feedbacktuning approach was proposed for optimal gains tuning of the proposed controller.Simulation results presented in this research illustrate that the proposed controllersuppresses the undesired in-plane vibration induced by environment or gripper 40 timesfaster than the nonlinear controller proposed in the literature. To suppress the maximuminput disturbance the maximum voltage was approximately 18 V which was less than thepull-in voltage of 30 V. The proposed controller is served to actuate two stator fingersadjacent to a rotor finger in order to provide both the attractive and repellent forcesduring manipulation. Employing the proposed mechanism not only resolves the drawbackscorresponding to the nonlinear controller presented in the literature but also improvesits performance of the closed loop system by using the complete nonlinear dynamics of theforce sensor. Also, applying complete non-linear dynamic of model improves the performanceof controller and is one of superior features of proposed PID controller in comparisonwith the classical controller presented in literature.

In this paper we present the design of a compact active cardiac stabilizer based onplanar compliant mechanisms and piezoelectric actuators. Considering an assembly of planarmanufactured structures helps to simplify the manufacturing process and may increase thecompactness. Parallel architectures constitute interesting solutions for their intrinsicstiffness properties, but in a planar configuration parallel manipulators often exhibitkinematic singularities. Two design approaches for planar parallel compliant mechanismsare presented in this paper. One design approach consists in designing a passive compliantmechanism in a configuration close to the singularity by introducing some asymmetriesduring the manufacturing process. The second design approach consists in taking advantageof the singularities of parallel manipulators to obtain non-trivial solutions. The newproposed active stabilizer, composed of planar compliant mechanisms, is introduced and itsperformances are discussed.

When operational modal analysis (OMA) is conducted on operating machines or structureswithout knowing excitations and perturbations neither the number of concerned frequencies,one problem raises on the validity of modal parameters identification (especially dampingratios) and on the precision of results obtained. This paper presents an OMA methodallowing for the evaluation of uncertainties of modal parameters (frequencies, dampingratios and mode shapes). The method is based on the vector autoregressive model (VAR) formultiple numbers of measured channels. It is seen that the uncertainty of modal parametersdecreases with higher model orders; the calculation of uncertainty allows also for theconstruction of an objective criterion for the selection of computing model order based ona threshold of confidence interval. The derivation confirms also that the identificationof natural frequencies deals with a smaller uncertainty compared with the damping ratioestimation, and hence it can be conducted with a lower computing model order. Numericalsimulations and experiments on a steel plate show the feasibility and the effectiveness ofthe developed OMA method.

The effects of punch geometry and sample size on forming limit diagrams in expansion areinvestigated in the case of a 2024 aluminium alloy. Four configurations were selected:flat punch (Marciniak test) or hemispheric punch and decimetric vs. centimetric toolingdimensions. Both decimetric and centimetric deep-drawing devices are associated with animage correlation tool that allows identifying without any contact the deformation on thesurface of planar or non-planar specimens. Strains on the surface of the samples areobserved by means of a double numerisation in three dimensions of the sample before andafter deformation by using stereoscopic vision and triangulation. Finally, deep-drawinglimit of the four configurations are compared in expansion state and with literature.Results mainly show that hemispherical punch allows measuring higher strains and is lesssensitive to size effect than Marciniak test.