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•One of the highest prevalence of dleptospirosis in Europe with human incidence rate 1.53/100000.•Increased risk for human infections was related to defined parameters.•Variations in ...seroprevalence and changing trends in prevailing serogroups were recorded.•Importance of continuous monitoring with constant multidisciplinary communication.
Leptospirosis is a geographically widespread and globally underestimated zoonosis that affects humans and variety of animals. To identify trends and possible risk factors, joined medical and veterinary teams investigated epidemiology and epizootiology of leptospirosis in Croatia. Retrospective analysis of data obtained from referent diagnostic laboratories included a total of 1917 human and 123964 animal sera tested in the period from 2009 to 2014. We found high human leptospirosis average incidence rate of 1.53/100000 with clear predominance of male patients older than 40 years (sex ratio M/F:3.2; median age 51±15.1years). Statistical analysis revealed seasonal and annual variations of incidence in humans that were primarily associated with favourable weather conditions (temperature 10–19, 9°C and precipitation above 100mm/m2). Majority of infections in humans were caused by serogroups Sejroe, Australis and Icterohaemorrhagiae. Notable variations in seroprevalence and changing trends in prevailing serogroups were recorded in most of the domestic animals and during the entire period of investigation. All of the observed findings underline leptospirosis as a significant human and veterinary public health threat and emphasize the importance of continuous multidisciplinary surveillance. We also argue that only input from both professions improves our overall knowledge on leptospirosis and leads to better and more efficient prevention and control strategies.
Fully generic 3D shapes of centrifugal roof fan vanes are explored based on a custom-developed numerical workflow with the ability to vary the vane 3D shape by manipulating the control points of ...parametric surfaces and change the number of vanes and rotation speed. An excellence formulation is based on design flow efficiency, multi-regime operational conditions and noise criteria for various cases, including multi-objective optimization. Multiple cases of optimization demonstrate the suitability of customized and individualized fan designs for specific working environments according to the selected excellence criteria. Noise analysis is considered as an additional decision-making tool for cases where multiple solutions of equal efficiency are generated and as an additional criteria for multi-objective optimization. The 3D vane shape enables further gains in efficiency compared to 2D shape optimization, while multi-objective optimization with noise as an additional criterion shows potential to greatly reduce the roof fan noise with only small losses in efficiency. The developed workflow which comprises (i) a 3D parametric shape modeler, (ii) an evolutionary optimizer and (iii) a computational fluid dynamics (CFD) simulator can be viewed as an integral tool for optimizing the designs of roof fans under custom conditions.
Vertical-axis wind turbines, such as Savonius-type wind turbines (SWT) are an attractive choice for small-scale electricity generation. Recent SWT research is mostly targeted at improving the SWT ...power coefficient, which is also the topic of this paper. The power coefficient was improved by optimization of a multi-blade SWT (2, 4 and 6), with blades based on circular arc segments. Additional optimization variables were the tip-speed ratio and the aspect ratio. The main novelty of this paper is the global optimization using genetic algorithm, which involved analysis of many different designs (∼105) using a validated 3D CFD model with a 4eq SST turbulence model. Since many designs were investigated, the optimization result is considered as the global optimal solution. In the 4 and 6-blade cases, the global optimal solution was similar to the previously proposed Scooplet-based design. The design was improved to achieve power coefficient cP = 0.32 with aspect ratio 1.5, and additionally cP = 0.34 with an increased aspect ratio of 2.5. Optimized designs were compared with a similar multiple quarter-blade design known from previous research (which was outperformed by 60%). For the 2-blade case a novel design was reached, which operates at TSR = 1.2, and achieves a 12% improvement over the classical SWT.
•Analysis of ∼105 Savonius-type wind turbine (SWT) designs using 3D CFD model.•Global optimization provided new 2,4 and 6-blade SWT designs.•2-blade design achieved 12% improvement over the classical SWT.•4 and 6-blade design achieved almost 50% improvement over the classical SWT.•3D CFD was validated against several experimental and numerical studies.
Simple design and low power coefficient of Savonius-style wind turbines make them attractive in experimental and computational fluid dynamics (CFD) based optimization studies. Still, after numerous ...studies the power coefficient is low, and the single optimal Savonius-style wind turbine shape and configuration is not known. This leaves room for improving the power coefficient, and the objective of this paper is to find an improved solution with application of smart numerical optimization.
Several Savonius blade improvements proposed by other researchers were initially analyzed. The numerical (3D CFD) analysis has shown that simple modifications of the blades can be better than more complicated shapes such as spline or elliptical curve. This has encouraged the investigation on what is the limit to the optimized design which used only simple circular-arc based blades. Thus, we perform a global optimization of Savonius blade pair where each pair is composed of two circular arc segments. The smart numerical optimization was performed using 2D CFD and the results were verified and compared with the previous designs using the 3D CFD. The selected optimization operating conditions were tip speed ratio 0.9 and wind speed 12 m/s. The novel optimized design achieved 39% improvement of the maximum power coefficient relative to the classical Savonius design.
Vertical-axis wind turbines (VAWT) are becoming popular solutions for electric power generation. Among them, Savonius-type VAWTs have low rotational speed, reduced noise and ability to self-start, ...but their disadvantage is the low energy conversion efficiency. This paper investigates a novel VAWT concept and whether it can provide a higher energy conversion efficiency. The novel concept is a Savonius-type VAWT with flexible blades that change their shape passively due to aerodynamic and blade inertial forces during rotation. An initial design was optimized by a customized shape optimization workflow based on genetic algorithms. The blade design evaluation was performed by CFD model with two-way fluid-structure interaction. The optimization objective was to determine the optimal blade shape, thickness distribution and location of the blade support arms by maximizing the power coefficient and keeping structural stresses below the design limit. The results show that 8% improvement of the power coefficient is possible while keeping the structural stress within the design limit. A detailed performance analysis in the paper shows that there is potential for further optimization considering annual energy production for a selected location. For that purpose, the proposed optimization workflow can serve as a tool for development of future designs.
•Novel concept of Savonius-type flexible vertical-axis wind turbine proposed.•The optimization workflow includes novel shape optimization method.•Flexible design can improve the power coefficient compared to the rigid design.•Proposed concept can be used for location-specific optimization.
Savonius-type vertical axis wind turbine (SWT) has several characteristics appropriate for urban usage: low rotational speed, low noise, easy self-starting; but also has a low power coefficient. One ...of the methods to improve the SWT efficiency is to use fixed deflector blades, but this makes the SWT performance sensitive to wind direction. This paper performs a robust optimization of deflector blade shape, considering the whole range of wind directions. The objectives are to reduce the required production material and to maximize the annual energy production (which is related to the average power coefficient cPave). Each design efficiency is estimated using 2D CFD transient simulation with GEKO turbulence model. The results show that cPave is increased to cPave = 0.35 using an 8-blade optimized deflector (46% improvement compared to no-deflector) coupled with classical SWT rotor. The 4-blade deflector is inferior with 33% improvement (cPave = 0.32) but with 60% material reduction compared to the previous design. Application of the novel Scooplet-based design achieves a further improvement of cPave = 0.43 and cP,ave = 0.385 for 4-blade and 8-blade deflectors, respectively. A selected optimized design was evaluated using 3D CFD for various aspect ratios (Ar).
This paper presents a numerical workflow designed and developed for autonomous synthesis of vertical axis wind turbine (VAWT) blades for maximum annual energy production at a specified location given ...by specified wind speed distribution and prescribed tip speed ratio. The workflow can synthesize shapes of both classical VAWT designs: Darrieus and Savonius rotors. This is achieved using a novel shape parameterization scheme based on B-splines which represents a compromise between shape generality and the multitude of shape variables. The developed computational framework enables the optimizer to synthesize and evaluate a variety of geometrically and even topologically different shapes such as the Darrieus and Savonius types. Moreover, the workflow can invent (i.e. numerically generate without a resembling initial shape) new generic shapes for custom operating conditions. Both single wind-speed and systems related to real-site operating conditions specified by a given distribution of wind speeds are considered. The developed workflow consists of efficient geometry parameterization, a genetic algorithm based optimizer and a computational fluid dynamics based simulator. The rather promising results of custom-shaped vertical axis wind turbines for maximum annual energy production at a given specific site are presented using a set of case studies.
•Numerical workflow for autonomous synthesis of vertical axis wind turbine blades.•Blades shape is synthesized for maximum annual energy production.•For different locations the workflow synthesizes different shapes.•The workflow can invent new shapes (without a resembling initial shape).•Several case studies are presented with promising results.
A computational framework for the shape optimization of wind turbine blades is developed for variable operating conditions specified by local wind speed distributions. The numerical workflow consists ...of a genetic algorithm based optimizer, a computational fluid dynamics based simulator and a 3D geometric modeller. The developed numerical workflow also implements the coupling of the process flows as well as passing data amongst the individual applications including the corresponding data mining. Several approaches to modeling 3D shapes are developed and employed by the workflow. They include parametric curves defining 2D curves lofted into 3D shapes in combination with applying computational geometry operators and full 3D parametric surface models which enable generic 3D shapes to be represented. The proposed definitions of excellence include annual energy production for given wind speed distributions and net-present-value and internal-rate-of-return based indicators as potential constituents of the fitness functions. Several case studies are presented with promising results towards the aspired custom-shaped wind turbine blades for optimum performance for any given specific location. The developed computational workflow can therefore be seen as a numerical device for custom optimization of performance of renewable energy systems.
•Fully generic modelling of 3-D blade shape using parametric entities.•Computationally efficient 3D CFD adopted for robust optimization.•Design excellence based on annual energy production for operating regime mix.•Financially realistic objective function is proposed.•Case studies with promising results for optimum performance blades.
Vezikularni stomatitis (VS) reemergentna je virusna zarazna bolest prije svega konja, goveda i svinja, ali i ovaca, koza, ljama i alpaka. Uzročnik bolesti je virus vezikularnog stomatitisa, arbovirus ...iz porodice Rhabdoviridae, u koju su uključeni različiti virusi kralježnjaka, beskralježnjaka i mnogih biljnih vrsta. Zbog nemogućnosti kliničkog razlikovanja od slinavke i šapa, vezikularni stomatitis u goveda i svinja iziskuje posebnu pozornost, iznimno kontagiozne zarazne bolesti papkara. Kliničkom slikom bolesti u konja i goveda dominira ptijalizam kao posljedica formiranja, a potom pucanja vezikula na dorzalnoj strani jezika, mekom nepcu, dentalnoj ploči i mukokutanom spoju usana. Lezije se nalaze i na krunskom djelu kopita, papaka, a u goveda i na sisama. Zbog erozija koje nastaju na mjestu rupturiranih vezikula bolesna životinja odbija hranu, a opiru se i mužnji. Za razliku od konja i goveda u kojih je obilno slinjenje, prvi simptom bolesti u svinja je šepanje koje izaziva lezije na krunskom djelu papaka. Bolest se unutar stada širi izravnim kontaktom, kontaminiranim predmetima, opremom i površinama, a veliku ulogu u širenju virusa VS imaju i insekti (komarci, pješčane muhe, mušice svrbljivice i komarčići), mehanički i/ili kao biološki vektori. Prevencija vezikularnog stomatitisa temelji se na izolaciji zaraženih stada, ograničenom kretanju primljivih životinja u zaraženom području, kontroli insekata (vektora) i uporabi cjepiva, dostupnih u nekim endemskim regijama Srednje i Južne Amerike. Povremena pojava infekcije u ljudi predstavlja određeno javno-zdravstveni problem. U ljudi bolest je blaga i slična je gripi te se smatra manje opasnom zoonozom.
A population of small mammals in Eastern Croatia was investigated in order to determine Leptospira carriage rates and identify circulating serovars.
•Leptospira carriage rate and circulating serovars ...investigated in small mammals.•Very high carriage rate detected (29.9%).•Three genomic species and five serovars detected.•Serogroups in small mammals correlate with serogroups in humans in that area.
In this survey we investigated a population of small mammals in Eastern Croatia in order to determine Leptospira carriage rates and identify circulating serovars. Out of 67 trapped animals, 20 (29.9%) isolates were obtained. Identification of isolates using microscopic agglutination test, pulsed field gel electrophoresis and multi locus sequence typing revealed that 10 (50.0%) isolates belong to serogroup Pomona, serovar Mozdok, 6 (30.0%) isolates to serogroup Australis, serovar Jalna, 2 (10.0%) isolates to serogroup Sejroe, serovar Saxkoebing, and 1 (5.0%) isolate to serogroup Grippotyphosa, serovar Grippotyphosa. One isolate from serogroup Bataviae was unable to be identified to the serovar level. Amplification of a 331-bp region of the locus LA0322 using real-time polymerase chain reaction determined that 12 (60.0%) isolates belong to L. kirschneri, 6 (30.0%) isolates to L. interrogans, and 2 (10.0%) isolates to L. borgpetersenii. Leptospira carriage rate was high (29.9%), which corresponds to a high incidence of human and domestic animal leptospirosis in Eastern Croatia. Furthermore, 90.0% of the isolates belong to serogroups Pomona, Australis and Sejroe which are also the most prevalent serogroups in humans in this area. These findings suggest that small mammals might be an important source of Leptospira spp. infection in Eastern Croatia.
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