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This work presents some numerical simulations, performed using AMESim software, for a system composed by two redundant servo-actuators. Certain operating conditions are taken into account for these two electro-hydrostatic servo-actuators, which are coupled to the command surface (aileron) of a transport aircraft. We first considered the situation of slight asymmetries in the construction of the servo-actuators, then a situation in which one servo-actuator fails at maximum flight speed, and then at a medium flight speed, and finally we considered the effect of gusts upon the system. Small differences in the construction of the servo-actuators were taken into consideration by modifying each of the pump displacements, one by +2% and one by −2%, from the nominal value. It is possible that many other asymmetries exist in the construction of servo-actuators, such as different liquid leakages in the cylinders or pumps, small differences in the controller coefficients, and so on. These differences should be taken into account in future works. Our results provide evidence that, under some operation situations of redundant servo-actuators, significant overstresses can appear in one servo-actuator, leading to a decrease in the time for which the system operates correctly. [ABSTRACT FROM AUTHOR]

The effects of various parameters on the performance of a straight bladed vertical axis wind turbine, using the vortex model, have been numerically investigated. A vortex model has been used to evaluate the performance of a vertical axis wind turbine, by means of aerodynamic characteristics of different airfoils for Reynolds numbers between 105 and 106. Parameters such as the thickness and the camber of the blade airfoil, the solidity, the type of blade profile, the number of blades and the pitch angle, which influence the power coefficient, CP, and the start-up regime. This study can be used in the designing an optimal vertical axis wind turbine in a specific location, when the prevailed wind regime is known.

The COVID-19 pandemic opened the doors for a corresponding "infodemic", associated with various misleading narratives related to the SARS-CoV-2 virus. As the way to stop the pandemic was unveiled, misleading narratives switched from the disease itself to the vaccine. Nevertheless, a rather scarce corpus of literature has approached the effects of these narratives on the willingness to take a vaccine against COVID-19. This study investigates how exposure to conspiracy narratives versus information that counter these narratives influences people's willingness to get vaccinated. Based on an experimental design, using a sample of Romanian students (N=301), this research shows that exposure to factual information related to COVID-19 vaccines meant to debunk conspiracy theories leads to higher willingness to vaccinate. Furthermore, this study shows that young, educated Romanians consider distant others to be more influenced by conspiracy theories on this topic, and, therefore, more prone to exhibit hesitancy towards COVID-19 vaccination. [ABSTRACT FROM AUTHOR]

This paper examines the digital behaviour on one widely used instant messaging (IM) platform, namely WhatsApp, of young people in Romania, with a focus on the reasons for sharing information on the platform and dependency of using it. Within the broad framework of the digital single market, little is known about the motivations and behavioural patterns of young Europeans while using the increasingly popular IM platforms, nor is it clear whether country characteristics are relevant or not when evaluating the impact of such technological platforms on the life of young audiences. Rooted in the uses and gratifications perspective, this study uses media diaries (N = 229), filled in by young people in an ordinary day of the week and self-administered questionnaires in order to assess what might be the main gratifications that lead young and educated people to share information on WhatsApp and what makes them spend more time and be dependent on the platform on a daily basis. Main results show that the most frequent reasons why young Romanians use WhatsApp are social, professional, and instrumental. Moreover, the tendency to share content on the platform is higher for people who use it for instrumental and informative purposes. Dependency on the platform is significantly higher for young people who use it to fulfil affective needs (i.e., to express or receive affection or emotional support and avoid loneliness). [ABSTRACT FROM AUTHOR]

Switchgrass (Panicum virgatum L.) is a lignocellulosic perennial grass with great potential in bioenergy field. Lignocellulosic bioenergy crops are mostly resistant to cell wall deconstruction, and therefore yield suboptimal levels of biofuel. The one-carbon pathway (also known as C1 metabolism) is critical for polymer methylation, including that of lignin and hemicelluloses in cell walls. Folylpolyglutamate synthetase (FPGS) catalyzes a biochemical reaction that leads to the formation of folylpolyglutamate, an important cofactor for many enzymes in the C1 pathway. In this study, the putatively novel switchgrass PvFPGS1 gene was identified and its functional role in cell wall composition and biofuel production was examined by RNAi knockdown analysis. The PvFPGS1 -downregulated plants were analyzed in the field over three growing seasons. Transgenic plants with the highest reduction in PvFPGS1 expression grew slower and produced lower end-of-season biomass. Transgenic plants with low-to-moderate reduction in PvFPGS1 transcript levels produced equivalent biomass as controls. There were no significant differences observed for lignin content and syringyl/guaiacyl lignin monomer ratio in the low-to-moderately reduced PvFPGS1 transgenic lines compared with the controls. Similarly, sugar release efficiency was also not significantly different in these transgenic lines compared with the control lines. However, transgenic plants produced up to 18% more ethanol while maintaining congruent growth and biomass as non-transgenic controls. Severity of rust disease among transgenic and control lines were not different during the time course of the field experiments. Altogether, the unchanged lignin content and composition in the low-to-moderate PvFPGS1 -downregulated lines may suggest that partial downregulation of PvFPGS1 expression did not impact lignin biosynthesis in switchgrass. In conclusion, the manipulation of PvFPGS1 expression in bioenergy crops may be useful to increase biofuel potential with no growth penalty or increased susceptibility to rust in feedstock. [ABSTRACT FROM AUTHOR]

The relationship between heavenly bodies and earthly behavior along with its importance took many centuries before the rigor scientific understanding enabled the true influences on Earth, such as its complicated motion and perceived other regularities in the behavior of earthly objects. One of these was the tendency for all things in one vicinity to move in the same downward direction according to the influence that is known as gravity property. Moreover, matter was observed to transform, sometimes, from one form into another, such as with melting of ice or vaporizing/cavitation of water, but the total quantity of that matter never seemed to change, which reflects the law at which we now refer to as the conservation/ integrity of mass, including its latent energy. Much latter it is noticed that planet Earth forms a self-regulating complex system, i.e. the Earth's surface is alive, that is known as the Gaia hypothesis, reflected in the Newton-Galilei dynamics through the law of equal action and reaction for stress vector and tensor, respectively. In addition, at was noticed that there are many material bodies with the important property that they retain their shapes, excepting the flowing fluids, whence the idea of rigid spatial motion arose, and it becomes possible to understood spatial relationships in terms a precise, well-defined geometry, the Euclidian three-dimensional geometry. Though the heavenly bodies are permanently moving in a self-built on universe like a timeless perpetuum mobile, the time remains an important property for the behaviors/motions of an Earth-bound object due to their relativity as against the diurnal rotation depending on the velocities of the impacted object. In contrast to the constant inertia condition where for small starting velocities and accelerations the Newton's determinist principle is applied, the onset of a motion of the Earth-bound material bodies, at higher velocities and accelerations (O(g)), involves changes of moving matter/inertia under influence of gravitational field via some intrinsic latent motions/processes. They achieve the kinetic-gravitational mutual energy transfer obeying the Galilei's law of inertia for self-equilibrating impact forces. The intrinsic motions, at the cellular scale (10-6 m), are responsible for the kinetic trinity of the momentum, kinetic energy and power, and they represent what it is called structured turbulence, i.e. a Galilean space-time structure according to the mathematical idea of a bundle (or fibre bundle) and its gauge connection. The bundle and gauge connection are a kind of Galilean transformation to a system moving with constant velocity carrying its relativistic non-inertial fraction as a blend of structure less turbulence and non-rigorously defined intermittency of a non-inertial motion. [ABSTRACT FROM AUTHOR]

In a continually changing global political environment, fake news has become a widely debated topic by both researchers and ordinary people. Despite the relevance and the diversity of approaches, few studies have focused on the typology of fake news in specialised scientific literature, while proper assessment methods and detection techniques are not well-established yet. This paper addresses the complex concept of fake news, presenting its significance and highlighting its different types, from propaganda to news satire; the moderators of the fake news effects and the ways to counter disinformation. This exploratory study reveals that solutions to combat the phenomenon exist, but they focus more on effects rather than on causes, leaving space open for further research. [ABSTRACT FROM AUTHOR]

General relativity describes the physical force of gravity and its relation with the space-time structure. The fundamental physical insight behind the theory of general relativity is that the effects of acceleration cannot be distinguished from those of gravity. The presence of matter changes the geometry of space and acceleration is experienced in relation to that geometry. In particular, the geometry of space and time is dynamically governed by physical laws that are not independently given. Such a case is the fluid turbulence which remained unexplained for over fifty years within the framework derived from the classical Navier-Stokes theory. The physical and mathematical problem of the genuine turbulence remains an unsolved one. This paper considers the turbulence as a manifestation of non-Newtonian behavior induced by the gravity-like accelerations at the beginning of motion. The fluid particles with high accelerations exhibit in wall-bound flows with large Reynolds number a sort of structure-less, background turbulence. It is shown that the relativistic viewpoint may solve the present paradigmatic crisis of turbulence. [ABSTRACT FROM AUTHOR]

Numerical investigations on the flow control around airfoils, in conjunction with Coandã effect, based on RANS equations are done. The circulation control uses the tangential blowing jet on the upper surface of the airfoil near the trailing edge with the rounded or modified flatback surface. Flow field spectra around such a configurations, involving the delayed of flow separation are obtained and analyzed by CFD methods. Thus can be identified the optimum domain of the geometric and jet flow parameters in which this flow control method should be used. [ABSTRACT FROM AUTHOR]

Coanda effect consists of the tendency of a jet to adhere to and to flow around nearby solid boundaries. This general class of phenomena, which may be observed in both liquid and gaseous jets, are known as the Coanda effect. In this paper, interest in the detailed behavior of an existing Coandă ejector model is taken, used in propulsion systems. The goal is to investigate the influence of various geometric parameters and pressure ratios on the Coandă ejector performance. The application of the Coandă effect to the directional control of a jet is also presented. Deviation of the thrust force by direct flow can be achieved by using the Coanda effect to change the angle of the primary jet engine exhaust nozzle. Since single jet flows or multi-jet flows are extensively applied in conjunction with the Coandă surface, as confined or free jet flows, in the last part of the paper, further insight into complexities involving issues such as the variety of flow structure and the related bifurcation and flow instabilities are provided. Thus, the conditions and the limits within which one can benefit from the advantages of Coandă-type flows are determined. [ABSTRACT FROM AUTHOR]

The application of the Coandă effect to the directional control of a jet or thrust is presented. Deviation of the thrust force by direct flow can be achieved by using the Coandă effect to change the angle of the primary jet engine exhaust nozzle. Major interest in the study of this phenomenon is caused by the possibility of using this effect for aircrafts with short take-off and landing, for thrust vectoring. The numerical investigations are performed using a RANS solver with an adequate turbulence model, showing a change of the jet direction. Thus, the conditions and the limits within which one can benefit from the advantages of Coandă-type flows are determined. [ABSTRACT FROM AUTHOR]

Objective: To develop and prototype a high-throughput microplate assay to assess anaerobic microorganisms and lignocellulosic biomasses in a rapid, cost-effective screen for consolidated bioprocessing potential.Results: Clostridium thermocellum parent Δhpt strain deconstructed Avicel to cellobiose, glucose, and generated lactic acid, formic acid, acetic acid and ethanol as fermentation products in titers and ratios similar to larger scale fermentations confirming the suitability of a plate-based method for C. thermocellum growth studies. C. thermocellum strain LL1210, with gene deletions in the key central metabolic pathways, produced higher ethanol titers in the Consolidated Bioprocessing (CBP) plate assay for both Avicel and switchgrass fermentations when compared to the Δhpt strain.Conclusion: A prototype microplate assay system is developed that will facilitate high-throughput bioprospecting for new lignocellulosic biomass types, genetic variants and new microbial strains for bioethanol production. [ABSTRACT FROM AUTHOR]

Summary: Sustainable utilization of lignocellulosic perennial grass feedstocks will be enabled by high biomass production and optimized cell wall chemistry for efficient conversion into biofuels. MicroRNAs are regulatory elements that modulate the expression of genes involved in various biological functions in plants, including growth and development. In greenhouse studies, overexpressing a microRNA (miR156) gene in switchgrass had dramatic effects on plant architecture and flowering, which appeared to be driven by transgene expression levels. High expressing lines were extremely dwarfed, whereas low and moderate‐expressing lines had higher biomass yields, improved sugar release and delayed flowering. Four lines with moderate or low miR156 overexpression from the prior greenhouse study were selected for a field experiment to assess the relationship between miR156 expression and biomass production over three years. We also analysed important bioenergy feedstock traits such as flowering, disease resistance, cell wall chemistry and biofuel production. Phenotypes of the transgenic lines were inconsistent between the greenhouse and the field as well as among different field growing seasons. One low expressing transgenic line consistently produced more biomass (25%–56%) than the control across all three seasons, which translated to the production of 30% more biofuel per plant during the final season. The other three transgenic lines produced less biomass than the control by the final season, and the two lines with moderate expression levels also exhibited altered disease susceptibilities. Results of this study emphasize the importance of performing multiyear field studies for plants with altered regulatory transgenes that target plant growth and development. [ABSTRACT FROM AUTHOR]

Transgenic Panicum virgatum L. silencing ( KD) or overexpressing ( OE) specific genes or a small RNA ( GAUT4- KD, mi RNA156- OE, MYB4- OE, COMT- KD and FPGS- KD) was grown in the field and aerial tissue analysed for biofuel production traits. Clones representing independent transgenic lines were established and senesced tissue was sampled after year 1 and 2 growth cycles. Biomass was analysed for wall sugars, recalcitrance to enzymatic digestibility and biofuel production using separate hydrolysis and fermentation. No correlation was found between plant carbohydrate content and biofuel production pointing to overriding structural and compositional elements that influence recalcitrance. Biomass yields were greater for all lines in the second year as plants establish in the field and standard amounts of biomass analysed from each line had more glucan, xylan and less ethanol (g/g basis) in the second- versus the first-year samples, pointing to a broad increase in tissue recalcitrance after regrowth from the perennial root. However, biomass from second-year growth of transgenics targeted for wall modification, GAUT4- KD, MYB4- OE, COMT- KD and FPGS- KD, had increased carbohydrate and ethanol yields (up to 12% and 21%, respectively) compared with control samples. The parental plant lines were found to have a significant impact on recalcitrance which can be exploited in future strategies. This summarizes progress towards generating next-generation bio-feedstocks with improved properties for microbial and enzymatic deconstruction, while providing a comprehensive quantitative analysis for the bioconversion of multiple plant lines in five transgenic strategies. [ABSTRACT FROM AUTHOR]

Biorefining of plant feedstocks into fuels and specialty chemicals, using biological conversion, requires the solubilization of lignocellulosics into simpler oligomeric compounds. However, non-pretreated woody biomass has shown high resistance to hydrolysis by cellulolytic microbes or purified cellulases. We investigate the limited solubilization of Populus deltoides by the cellulolytic thermophile Clostridium thermocellum in the absence of solute inhibitors. Compared to control samples, fermented poplar revealed that the hydrolysis of carbohydrates in secondary cell walls ceased prematurely as the presence of lignin increased at the surface. In quantitative fluorescence colocalization analysis by confocal laser scanning microscopy, the Manders’ coefficient of the fractional overlap between lignin and cellulose signals increased from an average of 0.67 to a near-maximum of 0.92 in fermented tissue. Chemical imaging by time-of-flight secondary ion mass spectrometry revealed a 49% decline in surface cellulose and a compensatory 30% and 11% increase in surface S- and G-lignin, respectively. Although 72% of the initial glucan was still present in the lignocellulose matrix of this feedstock, subsequent treatments with cell-free purified cellulases did not significantly restore hydrolysis. This confirmed that biomass surfaces had become non-productive for the C. thermocellum hydrolytic exoproteome. This study provides direct evidence for an explicit definition of feedstock recalcitrance, whereby depletion of surface carbohydrate increases lignin exposure which leads to inhibition of enzyme activity, while the bulk residual biomass retains significant undigested carbohydrate content. The analysis presented here establishes a novel method for the quantitation of lignocellulose recalcitrance. [ABSTRACT FROM AUTHOR]

A design method and analysis tool of an UAV propeller based on Blade Element Momentum Theory (BEMT) for low-Reynolds number flow is presented. BEMT is completed with 3D equilibrium- implementation, a post-stall model and swirl velocity considerations to improve the accuracy of the results. An open-source code, JBlade, based on BEMT is used to obtain performance curves in off-design cases for a given propeller. Finally, the results are analyzed for a UAV Hirrus propeller. This methodology can be used successfully in the preliminary design phase of an UAV propeller, whose data can then be used as input in an optimization method. [ABSTRACT FROM AUTHOR]

Background: Higher ratios of syringyl-to-guaiacyl (S/G) lignin components of Populus were shown to improve sugar release by enzymatic hydrolysis using commercial blends. Cellulolytic microbes are often robust biomass hydrolyzers and may offer cost advantages; however, it is unknown whether their activity can also be significantly influenced by the ratio of different monolignol types in Populus biomass. Hydrolysis and fermentation of autoclaved, but otherwise not pretreated Populus trichocarpa by Clostridium thermocellum ATCC 27405 was compared using feedstocks that had similar carbohydrate and total lignin contents but differed in S/G ratios. Results: Populus with an S/G ratio of 2.1 was converted more rapidly and to a greater extent compared to similar biomass that had a ratio of 1.2. For either microbes or commercial enzymes, an approximate 50 % relative difference in total solids solubilization was measured for both biomasses, which suggests that the differences and limitations in the microbial breakdown of lignocellulose may be largely from the enzymatic hydrolytic process. Surprisingly, the reduction in glucan content per gram solid in the residual microbially processed biomass was similar (17-18 %) irrespective of S/G ratio, pointing to a similar mechanism of solubilization that proceeded at different rates. Fermentation metabolome testing did not reveal the release of known biomass-derived alcohol and aldehyde inhibitors that could explain observed differences in microbial hydrolytic activity. Biomass-derived p-hydroxybenzoic acid was up to ninefold higher in low S/G ratio biomass fermentations, but was not found to be inhibitory in subsequent test fermentations. Cellulose crystallinity and degree of polymerization did not vary between Populus lines and had minor changes after fermentation. However, lignin molecular weights and cellulose accessibility determined by Simons' staining were positively correlated to the S/G content. Conclusions: Higher S/G ratios in Populus biomass lead to longer and more linear lignin chains and greater access to surface cellulosic content by microbe-bound enzymatic complexes. Substrate access limitation is suggested as a primary bottleneck in solubilization of minimally processed Populus, which has important implications for microbial deconstruction of lignocellulose biomass. Our findings will allow others to examine different Populus lines and to test if similar observations are possible for other plant species. [ABSTRACT FROM AUTHOR]

Combustion phenomenon is one of the most important problems involved in different industries, such as gas turbines, combustion chamber, melting of metals, etc. In this paper, combustion process of methane downstream of an axisymmetric sudden expansion in a circular pipe with a constant wall temperature has been studied. The conservation equations of mass, momentum, energy, and species as well as additional equations due to turbulence modeling have been numerically solved. The standard k-ε model and eddy dissipation combustion model has been used to simulate the turbulence and combustion phenomenon, respectively. Properties of gaseous mixture have been computed using the ideal gas equation of state. The governing equations have been discretized using a finite volume approach and power law scheme and the resulting set of algebraic equations has been solved simultaneously using the SIMPLER algorithm on a non-uniform staggered grid system. The numerical results have been compared with the other's numerical results and experimental data. [ABSTRACT FROM AUTHOR]

The goal of this paper is to provide a numerical flow analysis based on RANS equations in two directions: the study of augmented high-lift system for a cross-section airfoil of a wing up to transonic regime and the circulation control implemented by tangentially blowing jet over a highly curved surface due to Coanda effect on a rotor blade for a wind turbine. This study were analyzed the performance, sensitivities and limitations of the circulation control method based on blowing jet for a fixed wing as well as for a rotating wing. Directions of future research are identified and discussed. [ABSTRACT FROM AUTHOR]

In this paper we investigated numerically the dynamic stall phenomenon and the possibilities to control it, with application to vertical axis wind turbines (for urban users). The Phenomenon appear at low tip speed ratio (TSR<4) and it has a great impact on structural integrity of the wind turbine and power performances. For this reason we performed a computational study of dynamic stall around NACA 0012 airfoil in pitching motion at relative low Reynolds number (-105). Also, we performed the same analysis for four flow control methods: two passive (Gurney flap and slot) and two active (blowing jet on the rounded trailing edge and synthetic jet periodically activated). The Results are compared to those of an existing experimental case test. [ABSTRACT FROM AUTHOR]

Background Microbial cellulose conversion by Clostridium thermocellum 27405 occurs predominantly through the activity of substrate-adherent bacteria organized in thin, primarily single cell-layered biofilms. The importance of cellulosic surface exposure to microbial hydrolysis has received little attention despite its implied impact on conversion kinetics. Results We showed the spatial heterogeneity of fiber distribution in pure cellulosic sheets, which made direct measurements of biofilm colonization and surface penetration impossible. Therefore, we utilized on-line measurements of carbon dioxide (CO2) production in continuous-flow reactors, in conjunction with confocal imaging, to observe patterns of biofilm invasion and to indirectly estimate microbial accessibility to the substrate's surface and the resulting limitations on conversion kinetics. A strong positive correlation was found between cellulose consumption and CO2 production (R2 = 0.996) and between surface area and maximum biofilm activity (R2 = 0.981). We observed an initial biofilm development rate (0.46 h-1, 0.34 h-1 and 0.33 h-1) on Whatman sheets (#1, #598 and #3, respectively) that stabilized when the accessible surface was maximally colonized. The results suggest that cellulose conversion kinetics is initially subject to a microbial limitation period where the substrate is in excess, followed by a substrate limitation period where cellular mass, in the form of biofilms, is not limiting. Accessible surface area acts as an important determinant of the respective lengths of these two distinct periods. At end-point fermentation, all sheets were digested predominantly under substrate accessibility limitations (e.g., up to 81% of total CO2 production for Whatman #1). Integration of CO2 production rates over time showed Whatman #3 underwent the fastest conversion efficiency under microbial limitation, suggestive of best biofilm penetration, while Whatman #1 exhibited the least recalcitrance and the faster degradation during the substrate limitation period. Conclusion The results showed that the specific biofilm development rate of cellulolytic bacteria such as C. thermocellum has a notable effect on overall reactor kinetics during the period of microbial limitation, when ca. 20% of cellulose conversion occurs. The study further demonstrated the utility of on-line CO2 measurements as a method to assess biofilm development and substrate digestibility pertaining to microbial solubilization of cellulose, which is relevant when considering feedstock pre-treatment options. [ABSTRACT FROM AUTHOR]

The importance of bacterial adherence has been acknowledged in microbial lignocellulose conversion studies; however, few reports have described the function and structure of bioflims supported by cellulosic substrates. We investigated the organization, dynamic formation, and carbon flow associated with bioflims of the obligately anaerobic cellulolytic bacterium Clostridium thennocellum 27405. Using noninvasive, in situ fluorescence imaging, we showed biofilms capable of near complete substrate conversion with a characteristic monolayered cell structure without an extracellular polymeric matrix typically seen in biofilms. Cell division at the interface and terminal endospores appeared throughout all stages of bioflim growth. Using continuous-flow reactors with a rate of dilution (2 h-1) 12-fold higher than the bacterium's maximum growth rate, we compared biofllm activity under low (44 g/liter) and high (202 glliter) initial cellulose loading. The average hydrolysis rate was over 3-fold higher in the latter case, while the proportions of oligomeric cellulose hydrolysis products lost from the biofilm were 13.7% and 29.1% of the total substrate carbon hydrolyzed, respectively. Fermentative catabolism was comparable between the two cellulose loadings, with ca. 4% of metabolized sugar carbon being utilized for cell production, while 75.4% and 66.7% of the two cellulose loadings, respectively, were converted to primary carbon metabolites (ethanol, acetic acid, lactic acid, carbon dioxide). However, there was a notable difference in the ethanol-to-acetic acid ratio (gig), measured to be 0.91 for the low cellulose loading and 0.41 for the high cellulose loading. The results suggest that substrate availability for cell attachment rather than biofilm colonization rates govern the efficiency of cellulose conversion. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a NC toolpath generation strategy with tool engagement control for arbitrarily complex discrete part geometry, which reduces machining time and tool wear and can be used in high speed machining. The toolpath computation is based on image models for design part, raw stock and cutting tool, and involves pixel-based simulation of the milling process. Simulation results and comparison with existing methods are presented. [Copyright &y& Elsevier]

In this paper, a simulation environment for a short range 3D laser scanning system that uses triangulation is presented. The simulation is used for integrating a laser scanning probe that uses a line laser and two cameras, with a vertical articulated robotic arm with 6 degrees of freedom and a rotary table. The optical subsystem is simulated using POV-Ray ray tracing software, and the image processing for triangulation, together with the robotic arm kinematics and the user interlace, are implemented in MATLAB. [ABSTRACT FROM AUTHOR]

The purpose of these investigations is to study the possibilities to improve performances of a typical vertical axis wind turbines (VAWT), of Darrieus-type, using passive devices (mounted "on" or "inside" the blades of VAWT) to control dynamic flow separation (dynamic stall phenomenon). The passive devices considered for investigations are the Gurney flap, the slot or thin channel, and the turbulence promoters. Studies are performed numerically using computational fluid dynamics and where it is possible the results are compared with existent experimental or numerical data. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Self- starting is the major obstacle to be overcome for successful design of a vertical axis wind turbine (VAWT). In the past has been suggested that pitching the turbine blades such that pitch angle is not 90 degrees allows for self-starting. To understand the physics surrounding pitching, an analysis is carried out for a common airfoil profile, NACA 0012. The vortex model is used to predict aerodynamic performance of VAWT with pitched blades at various angles. As a result of the analysis carried out for the airfoil at various pitch angles, it was shown that the 'dead band' phenomenon could be overcome, but only slightly. At the same time, to overcome the 'dead band' with a level on confidence, torques in the tip speed ratio (TSR ) range of 0.75 to 2.75 must be increased to values further above zero. The paper aimed at giving an insight into the small wind turbine starting behavior and its influence parameters. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

In the last years, for home user, the wind turbine with vertical axis (VAWT) began to be more attractive due benefits in exploitation. In terms of aerodynamics, when the wind speed approaches the speed of operation (low value of tip speed ratio -TSR) the blade airfoil exceeds the critical angle of incidence for static conditions. Angle of incidence varies quickly across blade and the blade works in dynamic stall condition. The goal of the present work is to investigate the two-dimensional dynamic stall phenomenon around the NACA 0012 airfoil at relatively low Reynolds. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Influence of Interphase Mass Transfer (IMT) on the unsteady convective diffusion in a fluid flow through a tube surrounded by a porous medium is examined against the background of no IMT. The three coefficients namely exchange coefficient, convection coefficient, and dispersion coefficient are evaluated asymptotically at large-time. The exchange coefficient exists due to IMT. All-time analysis is made analytically when there is no IMT. The mean concentration distribution is measured at a point inside and outside the slug. The peak of mean concentration is higher than that of pure convection and it is further enhanced with increase of porous parameter. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]