Interference effects between duct and control vane on a micro air vehicle / Sheila Tobing, Tiauw Hiong Go and Roxana Vasilescu

A numerical study on the interference effects between duct and control vanes on a Vertical Takeoff and Landing Micro Air Vehicle is presented in this paper. The numerical analysis is conducted systematically with the solver first validated before it is applied to the full vehicle simulations. Different combinations of duct and control vanes are tested to determine the interactions between the two components and their effects on the vehicle's aerodynamics. The simulations show that the duct influences the local flow around the control vanes. The duct redirects the flow before it passes the control vanes, altering the aerodynamic forces and moment generated by the vanes as well as the vehicle. The control vanes generate lower aerodynamic forces and moments under the influences of the duct, compared to when they are simulated as isolated (individual) components. The over-predictions of the vehicle's aerodynamic forces and moments need to be taken into consideration in designing as they will introduce a high error to the design

Helicopter Blade Tip Vortex Modifications in Hover Using Piezoelectrically Modulated Blowing

Aeroacoustic investigations regarding different types of helicopter noise have indicated that the most annoying noise is caused by impulsive blade surface pressure changes in descent or forward flight conditions. Blade Vortex Interaction (BVI) is one of the main phenomena producing significant impulsive noise by the unsteady fluctuation in blade loading due to the rapid change of induced velocity field during interaction with vortices shed from previous blades. The tip vortex core structure and the blade vortex miss distance were identified as having a primary influence on BVI. In this thesis, piezoelectrically modulated and/or vectored blowing at the rotor blade tip is theoretically investigated as an active technique for modifying the structure of the tip vortex core as well as for increasing blade vortex miss distance. The mechanisms of formation and convection of rotor blade tip vortices up to and beyond 360 degrees wake age are described based on the CFD results for the baseline cases of a hovering rotor with rounded and square tips. A methodology combining electromechanical and CFD modeling is developed and applied to the study of a piezoelectrically modulated and vectored blowing two-dimensional wing section. The thesis is focused on the CFD analysis of rotor flow with modulated tangential blowing over a rounded blade tip, and with steady mid-plane blade tip blowing, respectively. Computational results characterizing the far-wake flow indicate that for steady tangential blowing the miss distance can be doubled compared to the baseline case, which may lead to a significant reduction in BVI noise level if this trend shown in hover can be replicated in low speed forward flight. Moreover, near-wake flow analysis show that through modulated blowing a higher dissipation of vorticity can be obtained.Ph.D.Committee Chair: Dancila, Stefan; Committee Member: Ruzzene, Massimo; Committee Member: Sankar, Lakshmi; Committee Member: Smith, Marilyn; Committee Member: Yu,Yun

Dimensionnement et exécution de pieux énergétiques : Validation par essais in-situ et en laboratoire

Les pieux énergétiques représentent une solution alternative intéressante, face à l’accroissement des besoins mondiaux en énergie et à la réduction de l’utilisation des énergies fossiles. L’objectif principal de la thèse est d’identifier et de quantifier les principaux facteurs influençant le dimensionnement des pieux géothermiques, qui sont impactés par les changements de température des pieux lors de leur activité. Pour ce faire, ce travail de thèse a été dressé en 3 campagnes expérimentales, dont deux à échelle réelle : (i) une première campagne à chargement thermomécanique contrôlé (Marne La Vallée), (ii) une seconde campagne en conditions d’utilisation réelles sous une station d’épuration (Sept Sorts) et (iii) une troisième campagne à l’échelle du laboratoire grâce à une nouvelle machine de cisaillement direct d’interface permettant l’étude du comportement thermo mécanique des interfaces sol-structure. Ces trois campagnes expérimentales ont pour but de quantifier l’effet de la température et des cycles de température sur le comportement des pieux énergétiques. Les premiers résultats expérimentaux de la campagne de Sept Sorts ont ensuite été simules dans le code LAGAMINE via la méthode des éléments finis, afin d’adopter une approche complémentaire permettant de mieux appréhender la réponse thermomécanique de ce type de pieu lors de l’activation géothermique. et (iii) une troisième campagne à l’échelle du laboratoire grâce à une nouvelle machine de cisaillement direct d’interface permettant l’étude du comportement thermo mécanique des interfaces sol-structure. Ces trois campagnes expérimentales ont pour but de quantifier l’effet de la température et des cycles de température sur le comportement des pieux énergétiques. Les premiers résultats expérimentaux de la campagne de Sept Sorts ont ensuite été simules dans le code LAGAMINE via la méthode des éléments finis, afin d’adopter une approche complémentaire permettant de mieux appréhender la réponse thermomécanique de ce type de pieu lors de l’activation géothermique.Energy piles, also called thermo-active piles, are an alternative solution to the increase in the global energy demand as well as in mitigating socio-economical stakes concerning the increase of energy costs due to fossil fuels. Energy piles are double purpose structures that allow transferring the loads from the superstructure to the soil and that integrate pipe circuits allowing heat exchange between the pile and the surrounding ground. The objective of this thesis is to identify and quantify the principal parameters involved in the geotechnical design of pile foundations impacted by temperature changes associated with geothermal activation. For this purpose, this research work was organized in 3 experimental campaigns: (i) A full scale load controlled test at Ecole des Ponts Paris-Tech, (ii) Full scale energy piles monitoring under real exploitation conditions at Sept Sorts, (Seine et Marne, France), (iii) Laboratory tests in order to assess the effect of temperature and temperature cycles at the soil-pile interface. The experimental results are used to estimate the effect of geothermal activation of a pile foundation, on its bearing capacity as well as on its long-term exploitation. Finally, preliminary numerical simulations were performed using a thermo-hydro mechanical model, using the finite element method code LAGAMINE able to capture the main phenomena

Dimensionnement et exécution de pieux énergétiques : Validation par essais in-situ et en laboratoire

Energy piles, also called thermo-active piles, are an alternative solution to the increase in the global energy demand as well as in mitigating socio-economical stakes concerning the increase of energy costs due to fossil fuels. Energy piles are double purpose structures that allow transferring the loads from the superstructure to the soil and that integrate pipe circuits allowing heat exchange between the pile and the surrounding ground. The objective of this thesis is to identify and quantify the principal parameters involved in the geotechnical design of pile foundations impacted by temperature changes associated with geothermal activation. For this purpose, this research work was organized in 3 experimental campaigns: (i) A full scale load controlled test at Ecole des Ponts Paris-Tech, (ii) Full scale energy piles monitoring under real exploitation conditions at Sept Sorts, (Seine et Marne, France), (iii) Laboratory tests in order to assess the effect of temperature and temperature cycles at the soil-pile interface. The experimental results are used to estimate the effect of geothermal activation of a pile foundation, on its bearing capacity as well as on its long-term exploitation. Finally, preliminary numerical simulations were performed using a thermo-hydro mechanical model, using the finite element method code LAGAMINE able to capture the main phenomena.Les pieux énergétiques représentent une solution alternative intéressante, face à l’accroissement des besoins mondiaux en énergie et à la réduction de l’utilisation des énergies fossiles. L’objectif principal de la thèse est d’identifier et de quantifier les principaux facteurs influençant le dimensionnement des pieux géothermiques, qui sont impactés par les changements de température des pieux lors de leur activité. Pour ce faire, ce travail de thèse a été dressé en 3 campagnes expérimentales, dont deux à échelle réelle : (i) une première campagne à chargement thermomécanique contrôlé (Marne La Vallée), (ii) une seconde campagne en conditions d’utilisation réelles sous une station d’épuration (Sept Sorts) et (iii) une troisième campagne à l’échelle du laboratoire grâce à une nouvelle machine de cisaillement direct d’interface permettant l’étude du comportement thermo mécanique des interfaces sol-structure. Ces trois campagnes expérimentales ont pour but de quantifier l’effet de la température et des cycles de température sur le comportement des pieux énergétiques. Les premiers résultats expérimentaux de la campagne de Sept Sorts ont ensuite été simules dans le code LAGAMINE via la méthode des éléments finis, afin d’adopter une approche complémentaire permettant de mieux appréhender la réponse thermomécanique de ce type de pieu lors de l’activation géothermique. et (iii) une troisième campagne à l’échelle du laboratoire grâce à une nouvelle machine de cisaillement direct d’interface permettant l’étude du comportement thermo mécanique des interfaces sol-structure. Ces trois campagnes expérimentales ont pour but de quantifier l’effet de la température et des cycles de température sur le comportement des pieux énergétiques. Les premiers résultats expérimentaux de la campagne de Sept Sorts ont ensuite été simules dans le code LAGAMINE via la méthode des éléments finis, afin d’adopter une approche complémentaire permettant de mieux appréhender la réponse thermomécanique de ce type de pieu lors de l’activation géothermique

Numerical modelling of energy piles under combined loading

International audienceThe growing use of fossil fuels and other non-renewable energy sources has made climate change a critical global issue. In order to counter this threat, several countries are engaged in an ecological transition, and are looking for technologies using renewable energy sources. In this context, energy geostructures, such as thermo-active (or energy) piles, have been developed, consisting in fixing heat exchanger pipes to the reinforcement cages of foundation piles to extract/inject the heat from/into the ground with the purpose of meeting the building heating and cooling demands. Their specificity is their dual function: structural support and energy exchanger. In the case of energy piles, two aspects can be critical and should be considered in their design. The first is the nature of the cyclic thermal loading, which can affect the mechanical response of the energy pile. In fact, during temperature variation along the pile, stresses change and pile head movements are induced (Figure 1), due to the thermal dilatancy/contraction of the pile and the behaviour of the soil-pile interface [1, 2, 3, 4, 5, 6]. Consequently, cyclic thermal loading can induce a deterioration of the shear stresses at the soil-pile interface and hence a deterioration of the pile's bearing capacity [7]. The second aspect concerns the adaptation of design under combined lateral and axial loads. Indeed, the co-existence of a lateral loading can affect the axial response of the pile and vice-versa [8]. These configurations are the most favourable for installing heat exchanger pipes since, mechanically, they require reinforcement cages all along the pile height. Studies on energy piles have mainly investigated their behaviour under axial loading. Energy piles under lateral loading have hardly been considered [9]. The aim of this paper is to present a practical calculation tool for modelling energy piles that takes into account the combined loading on the pile response. An original 1D finite element approach is developed for engineering practice, taking into account the rheology of the problem. The pile is discretised in beam finite elements with three degrees of freedom at each node (vertical displacement, horizontal displacement and rotation). The soil is modelled by surface shear and normal springs. This tool is based on the solution of the equilibrium equation of the global system by an iterative plastic correction procedure. This correction is based on the yield criterion defined in the code. The main strength of this approach lies in its capability to consider a 3D failure envelope for an energy pile, capturing its behaviour under combined axial, lateral and cyclic thermal loading. It can clearly represent the critical effects of these loads by adopting an appropriate behaviour law for the soil-pile interface. In addition to being practical and easy to use, this tool has the advantage of reducing calculation time compared to more complex 3D numerical methods, especially in the case of cyclic thermal loading

China-Angola Investment Model

In the aftermath of Angola’s civil war, strong economic relations developed between the country and the People’s Republic of China. Our study addresses China’s investment risks in Angola, considering an infrastructure-for-petroleum partnership between these two countries. The main working hypothesis is that the recovery of Chinese investments made in Angola is has translated into thousands of barrels of petroleum being imported daily from Angola. We analyzed the main economic, social, and political indicators that describe the situation in Angola that could impact the recovery of Chinese loans in the form of oil exports. Data processing implied involved regression-based imputation, MinMax data normalization, the use of the Analytical Hierarchy Process (AHP), and econometric analysis, next to the construction of a composite risk indicator. The results of the econometric analysis highlighted that an increase in the composite risk indicator of 1% leads to a decrease in the quantity of petroleum exported by almost 6377 barrels per day. Because, at least in the short run, the economic diversification in Angola is weak, and the most important asset is its oil, the partnership with China will continue to exist. This cooperation model represents a source of economic growth and infrastructure development for Angola and a source of energy that fuels China—one of the most powerful economies in the world

Progress in Electrochemical (Bio)Sensors for Monitoring Wine Production

Electrochemical sensors and biosensors have been proposed as fast and cost effective analytical tools, meeting the robustness and performance requirements for industrial process monitoring. In wine production, electrochemical biosensors have proven useful for monitoring critical parameters related to alcoholic fermentation (AF), malolactic fermentation (MLF), determining the impact of the various technological steps and treatments on wine quality, or assessing the differences due to wine age, grape variety, vineyard or geographical region. This review summarizes the current information on the voltamperometric biosensors developed for monitoring wine production with a focus on sensing concepts tested in industry-like settings and on the main quality parameters such as glucose, alcohol, malic and lactic acids, phenolic compounds and allergens. Recent progress featuring nanomaterial-enabled enhancement of sensor performance and applications based on screen-printed electrodes is emphasized. A case study presents the monitoring of alcoholic fermentation based on commercial biosensors adapted with minimal method development for the detection of glucose and phenolic compounds in wine and included in an automated monitoring system. The current challenges and perspectives for the wider application of electrochemical sensors in monitoring industrial processes such as wine production are discussed

Digital globalization and its impact on economic and social life

Research background: While some researchers see digital globalization as a new form of globalization, others liken digitalisation to the globalization that needs to be managed and driven so that institutions and businesses can meet the challenge of digitalisation together. Digitization has encompassed all aspects of economic and social life. In increasingly fierce competition, technological advances and the challenges of science are becoming catalysts for globalization. There is research that suggests that conventional wisdom would say that globalization has stopped arguing that global trade in goods has flattened and cross-border capital flows have fallen sharply since the economic crisis of 2008. However, research shows that globalization is not reversing but enters a new phase that could be defined by a sustained increase in data and information flows. More than a decade later, the new global crisis caused by the COVID-19 pandemic is strengthening the role of information and communication technologies in both the economy and social life. Purpose of the article: The aim of this paper is to highlight the main characteristics of digital globalization that have a major impact on current and future economic and social life. Methods: Documentary analysis and review of the literature are the main research methods. These are doubled by a bibliographic analysis of IT tools. Findings & Value added: Following the documentary analysis, we identified a series of characteristics that allow us to consider that global digitalization can become the determining factor of the economy with direct implications in social life