904 research outputs found

    Thrust vectoring for lateral-directional stability

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    The advantages and disadvantages of using thrust vectoring for lateral-directional control and the effects of reducing the tail size of a single-engine aircraft were investigated. The aerodynamic characteristics of the F-16 aircraft were generated by using the Aerodynamic Preliminary Analysis System II panel code. The resulting lateral-directional linear perturbation analysis of a modified F-16 aircraft with various tail sizes and yaw vectoring was performed at several speeds and altitudes to determine the stability and control trends for the aircraft compared to these trends for a baseline aircraft. A study of the paddle-type turning vane thrust vectoring control system as used on the National Aeronautics and Space Administration F/A-18 High Alpha Research Vehicle is also presented

    Einstein is still right: New tests of gravitational dynamics in the field of the Earth

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    It is presented and discussed here a recent analysis of LAGEOS II laser tracking data, which led to the first direct verification of the gravitoelectric relativistic precession in the field of the Earth, and to the simultaneous measurement of the Lense-Thirring and de Sitter effects. Emphasis is given on the analysis strategy and the modelization issues. It is also shown a further result, consisting in a new limit, much more stringent than the previous ones, on a possible non-Newtonian(Yukawa-like) interaction, acting at the scale of the system semimajor axis

    Multiaxis thrust vectoring using axisymmetric nozzles and postexit vanes on an F/A-18 configuration vehicle

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    A ground-based investigation was conducted on an operational system of multiaxis thrust vectoring using postexit vanes around an axisymmetric nozzle. This thrust vectoring system will be tested on the NASA F/A-18 High Alpha Research Vehicle (HARV) aircraft. The system provides thrust vectoring capability in both pitch and yaw. Ground based data were gathered from two separate tests at NASA Langley Research Center. The first was a static test in the 16-foot Transonic Tunnel Cold-Jet Facility with a 14.25 percent scale model of the axisymmetric nozzle and the postexit vanes. The second test was conducted in the 30 by 60 foot wind tunnel with a 16 percent F/A-18 complete configuration model. Data from the two sets are being used to develop models of jet plume deflection and thrust loss as a function of vane deflection. In addition, an aerodynamic interaction model based on plume deflection angles will be developed. Results from the scale model nozzle test showed that increased vane deflection caused exhaust plume turning. Aerodynamic interaction effects consisted primarily of favorable interaction of moments and unfavorable interaction of forces caused by the vectored jet plume

    Recombinant 60-kda Heat Shock Protein From Paracoccidioides Brasiliensis: Is It A Good Antigen For Serological Diagnosis Of Paracoccidioidomycosis?

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    Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Paracoccidioides brasiliensis and P. lutzii are fungi that cause paracoccidioidomycosis (PCM), the most prevalent systemic mycosis in South America. For serological diagnosis, although 43-kDa glycoprotein (gp43) is regarded as highly specific for PCM, the occurrence of false negative reactions in sera from patients infected with P. lutzii suggests that preparation with only one antigen is not recommended. Heat shock proteins are feasible alternatives as a second antigen because they are often highly immunogenic. In this study, we evaluated the usefulness of recombinant 60-kDa heat shock protein from P. brasiliensis (rPbHsp60) for the serological diagnosis of PCM. Using western blotting assay, we observed that 77.3% of the sera from PCM patients were positive to rPbHsp60, with 90.9% positivity to recombinant gp43 (rgp43). More importantly, sera from healthy subjects had 27% positivity to rPbHsp60 and none to rgp43. When rPbHsp60 was used in ELISA, we did not observe significant differences between the reactions with sera from PCM patients and healthy subjects, while the difference was clearly evident when the antigen was rgp43. Furthermore, rPbHsp60 was recognized by sera from patients with histoplasmosis, aspergillosis, sporotrichosis or tuberculosis in an ELISA test. These results show that rPbHsp60 is not a good antigen for PCM diagnosis.504Sao Paulo Research Foundation (FAPESP) [2013/12278-3]FAPESP [2012/07924-0, 2009/03235-3, 2012/08552-0]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

    Chemical Composition and Antioxidant Activity of Essential Oil from the Aerial Parts of Teucrium luteum (Mill.) Degen subsp. flavovirens (Batt.) Greuter & Burdet Growing Wild in Tunisia

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    Essential oils (EOs), the odorous and volatile products of a plant's secondary metabolism, have wide applications in folk medicine, in food flavoring and preservation, and in fragrance industries. The aim of this study was to analyze the chemical composition of the EO from the aerial parts (including the inflorescences) of wild Teucrium luteum subsp. flavovirens from Tunisia. The EO obtained by the hydrodistillation of air-dried plant material in a Clevenger-type apparatus was analyzed using gas chromatography coupled with mass spectrometry (GC-MS). Fifty-three components representing 83.9% of the total constituents were identified. The EO of T. luteum subsp. flavovirens is characterized by the presence of beta-elemol (7.2%), (+)-alpha-pinene (6%), beta-eudesmol (5.5%), guaiol (4.2%), alpha-bisabolol (4.2%), and beta-caryophyllene (4.1%) as principal chemical components. In vitro (DPPH and beta-carotene bleaching assays), it showed significantly higher radical scavenging and antioxidant properties than the reference compound, BHT. To the best of our knowledge, this is the first report describing the composition and antioxidant properties of the EO from Tunisian T. luteum subsp. flavovirens. Our preliminary data will help to valorize this potentially useful plant species from Tunisia and represent a starting point for further studies on its volatile fraction

    In situ formation of low molecular weight organogelators for slick solidification

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    We have investigated the in situ formation of Low Molecular Weight Organogelator (LMWO) molecules in oil-on-water slicks through dual reactive precursor injection. This method alleviates the need for any carrier solvent or prior heating, therefore reducing the environmental impact of LMWOs, giving instantaneous gelation, even at low temperatures (−5 °C). We show minimal leaching from our gels into the water layer

    Structural and Thermal Behaviour of a Timber-concrete Prefabricated Composite Wall System

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    Abstract Wood is the oldest building materials and still now it plays an important role in the construction sector. There are many general advantages in using timber for building purposes. First of all, it is an environmentally friendly, easily recyclable material; it has a low weight in relation to strength, which is advantageous for transport, handling and production; moreover wood has aesthetic qualities, which give great possibilities in architectural design. Lastly wooden structures have an excellent performance in case of earthquake if compared to traditional structures. In Europe the development of the timber-concrete composite structures (TCC) began during a shortage of steel for reinforcement in concrete in the beginning of XX century. TCC application was primarily a refurbishment technique for old historical buildings, during the last 50 years interest in TCC systems has increased, resulting in the construction also of new buildings. This paper presents the analysis of the structural and thermal behaviour of an timber-concrete prefabricated composite wall system, the Concrete Glulam Framed Panel (CGFP) which is a panel made of a concrete slab and a structural glulam frame. The research analyses the structural performance with quasi-static in-plane tests, focused on the in-plane strength and stiffness of individual panels, and the thermal behaviour of the system with steady state tests using an hot box apparatus. The results validate the efficacy of proposed system ensuring the resistance and the dissipative structural behaviour through the hierarchy response characterized by the wood frame, the braced reinforced concrete panel of the singular module and by the rocking effects of global system. On the other side hot-box measures demonstrated a high level of thermal resistance of the system reaching U-values around 0,20 W m -2 K -1 . Moreover experimental data permitted to calibrate a FEM model with which will be possible to study and analyse the panels in different conditions and configuration in both mechanical and thermal field

    DYNAMICAL SIMULATION OF A VALVETRAIN MECHANISM: AN ENGINEERING EDUCATION APPROACH

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    The present work aims to present a valvetrain model considering the dynamics functioning aspects of an Otto’s engine. The model will be constructed using Adams/View® software, which is a powerful modeling and simulating environment of dynamic systems. It allows building, simulating, refining and optimizing any mechanical system. In fact, the model will help engineering students to understand how the mechanism works, in terms of displacement, velocity and acceleration of the valve as a function of the time. It is also possible to know the behavior of the force in the spring as a function of the time and, finally, the torque applied in the cam due to a angular velocity input. Relative to spring force, during the Otto engine cycle, the cam lobe must be able to open and close the valve as fast and as smoothly as possible. The force responsible to close the valve is applied by the valve spring, which is also responsible for keeping contact between the cam lobe and the valve. Dynamic forces impose limits on cam and valve lift. Thus, the simulation model allows determining these forces and displacements through the cam rotation. As main objectives the authors wish to make available a model which is capable to show in 3D the animation of a valvetrain mechanism of an Otto engine, obtaining the main curves for analysis and evaluation of this mechanism performance

    [sup]1H NMR quantification of spray dried and spray freeze-dried saccharide carriers in dry powder inhaler formulations

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    Quantitative analysis using proton NMR (1H qNMR) has been employed in various areas such as pharmaceutical analysis (e.g., dissolution study), vaccines, natural products analysis, metabolites, and macrolide antibiotics in agriculture industry. However, it is not routinely used in the quantification of saccharides in dry powder inhaler (DPI) formulations. The aim of this study was to develop a 1H NMR method for the quantification of saccharides employed in DPI formulations. Dry powders as DPI carriers were prepared by spray drying (SD) and spray freeze drying (SFD) using three saccharides: namely D-mannitol, D-sorbitol and D-(+)-sucrose. The calibration curves constructed for all three saccharides demonstrated linearity with R2 value of 1. The 1H qNMR method produced accurate (relative error %: 0.184-3.697) and precise data with high repeatability (RSD %: 0.517-3.126) within the calibration curve concentration range. The 1H qNMR method also demonstrated significant sensitivity with low values of limit of detection (0.058 mM for D-mannitol, 0.045 mM for D-(+)-sucrose, and 0.056 mM for D-sorbitol) and limit of quantitation (0.175 mM for D-mannitol, 0.135 mM for D-(+)-sucrose, and 0.168 mM for D-sorbitol). Pulmonary deposition via impaction experiments of the three saccharides was quantified using the developed method. It was found that SFD D-mannitol (68.99%) and SFD D-(+)-sucrose (66.62%) exhibited better delivered dose (total saccharide deposition in throat and all impactor stages) than SD D-mannitol (49.03%) and SD D-(+)-sucrose (57.70%) (p< 0.05). The developed 1H qNMR methodology can be routinely used as an analytical method to assess pulmonary deposition in impaction experiments of saccharides employed as carriers in DPI formulations
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