Aerodynamic Load Analysis of a Variable Camber Continuous Trailing Edge Flap System on a Flexible Wing Aircraft

This paper presents an investigative aerodynamic analysis conducted on the novel control surface known as a Variable Camber Continuous Trailing Edge Flap (VCCTEF). The VCCTEF is modeled as a control effector on the NASA Generic Transport Model (GTM) where wing flexibility is considered. Aerodynamic modeling of the aircraft is conducted using vortex-lattice method (VLM), and an aeroelastic model of the aircraft that utilizes a coupled finite-element analysis (FEA) vortex-lattice solution is employed. VLM solutions are used to determine quasi-steady aerodynamic loading over the aeroelastic wing structures with VCCTEF. The load data is used to calculate aerodynamic sensitivities to control surface deployment and is also integrated to determine overall hinge moments. This analysis is conducted for different flight conditions, where control sensitivities compare the VCCTEF effectiveness against conventional control surfaces. Hinge moment results provide insight into aeroelastic wing loads, and worst case hinge moments for the VCCTEF can be estimated. Results show that the VCCTEF offers greater control authority than conventional ailerons at cruise, and nominal flap settings are determined for a low-speed take-off condition where the VCCTEF maintains comparable control effectiveness. Worst case hinge moment values are presented, where for a possible VCCTEF configuration, the stiff wing model demonstrates up to a 5.90 percent increase in flap hinge moment relative to a rigid model, and a reduced stiffness model demonstrates up to an 11.42 percent increase

Coupled Vortex-Lattice Flight Dynamic Model with Aeroelastic Finite-Element Model of Flexible Wing Transport Aircraft with Variable Camber Continuous Trailing Edge Flap for Drag Reduction

This paper presents a coupled vortex-lattice flight dynamic model with an aeroelastic finite-element model to predict dynamic characteristics of a flexible wing transport aircraft. The aircraft model is based on NASA Generic Transport Model (GTM) with representative mass and stiffness properties to achieve a wing tip deflection about twice that of a conventional transport aircraft (10% versus 5%). This flexible wing transport aircraft is referred to as an Elastically Shaped Aircraft Concept (ESAC) which is equipped with a Variable Camber Continuous Trailing Edge Flap (VCCTEF) system for active wing shaping control for drag reduction. A vortex-lattice aerodynamic model of the ESAC is developed and is coupled with an aeroelastic finite-element model via an automated geometry modeler. This coupled model is used to compute static and dynamic aeroelastic solutions. The deflection information from the finite-element model and the vortex-lattice model is used to compute unsteady contributions to the aerodynamic force and moment coefficients. A coupled aeroelastic-longitudinal flight dynamic model is developed by coupling the finite-element model with the rigid-body flight dynamic model of the GTM

Investigation of the estrogenic activity of Pueraria candollei variety mirifica extract on rats

Background: Pueraria candollei variety mirifica (PM) has been widely used as ingredient in many rejuvenating products. In this study, we aimed to assess the estrogenic activity of PM extract grown in Vietnam.Methods: Estrogenic activity of PM extract was estimated on immature female rats by using uterotrophic method to measure the weight of the reproductive organs. Estrogenic activity of PM extract also was investigated in mature female ovariectomized rats by evaluating the vaginal cells growth, reproductive organs weight, serum estradiol concentration.Results: Our results showed that PM extract at doses of 100 mg/kg, 200 mg/kg had increased the reproductive organs weight in immature rats and female ovariectomized rats. In addition, PM extract had increased the serum estradiol concentration and the vaginal cells growth by increasing the percentage of keratinocytes in female ovariectomized rats.Conclusions: Our results showed that PM extract has strong estrogenic activity in rats

Postbuckling of functionally graded cylindrical shells based on improved Donnell equations

This paper presents an analytical approach to investigate the buckling and postbuckling of functionally graded cylindrical shells subjected to axial and transversemechanical loads incorporating the effects of temperature. Material properties are assumed to be temperature independent, and graded in the thickness direction accordingto a simple power law distribution in terms of the volume fractions of constituents. Equilibrium equations for perfect cylindrical shells are derived by using improved Donnell shell theory taking into account geometrical nonlinearity. One-term approximate solution is assumed to satisfy simply supported boundary conditions and closed-form expressions of buckling loads and load-deflection curves are determined by Galerkin method. Analysis shows the effects of material and the geometric parameters, buckling mode, pre-existent axial compressive and thermal loads on the nonlinear response of the shells

Dinophysis spp. recorded in the coastal waters of northern Vietnam during 2002-2003

A monitoring on toxins responsible for Diarrhetic Shellfish Poisoning (DSP) was carried out at several culture areas of hard clam (Meretrix meretrix) in the northern coast of Vietnam during May 2002 and December 2003. Quantitative observation of Dinophysis spp. was made one to four times every month and DSP toxins in the hard clam grown in the area was analyzed monthly using the HPLC method. Six species of Dinophysis were recorded, including D. caudata, D. fortii, D. miles, D. rotundata, D. mitra and D. hastata. Among them, D. caudata was the most common species. Others were not common and their densities were ignorable. D. caudata appeared almost all around the year at all sampling sites with density ranged from 0 to more than 3000 cells/l. However, it was more abundant during the warm period, i.e. from late February to late November. For the rest of a year, cells were rarely found. D. caudata was recorded in a wide range of temperature (15-34.3℃), but its significant density (over 100 cells/l) was only observed when water temperature exceeded 20℃. D. caudata appeared and could reach high density at all salinity in the range of 8-34 PSU. The highest recorded density was 3128 cells/l at 22℃ and 8.2 PSU in Thanh Hoa area in February 2003. ""Blooms"" of D. caudata, together with other dominant dinoflagellates, usually coincided with the vanishing period of diatoms. Okadaic acid (OA) was detected in edible part of clams but at low concentration in all samples. Maximal level was 80ng OA/100g, encountered in Thanh Hoa transect during August 2002 and April 2003. DTX 1-4 were not detected in all samples. No significant correlation between OA concentration in clam and the density of D. caudata in the water sample was observed, although toxins sometimes peaked the same time with D. caudata density. Low concentration of toxins implicates low risk of DSP and explains the absence of poisoning cases in the area so far. However, other shellfishes in the area should also be subjected to toxin monitoring

Approximation solution for steel concrete beam accounting high-order shear deformation using trigonometric-series

Steel concrete beams have a reasonable structure in terms of using material and high load carrying capacity. This paper deals with an approximate solution based on a trigonometric series for the static of steel concrete beams. The displacement field is based on the higher-order theory using Reddy’s hypothesis. The governing equations are derived from variation principles. An approximate solution based on the representation of displacement fields by trigonometric series is developed to solve the static problem of steel concrete beams. In order to verify the accuracy of the present approximate solution, numerical results are compared with those of exact solutions using classical beam theory. The displacements and nominal stress distributions in the depth direction are obtained with various high of beams. The present approximate approach can accurately predict the displacements and stresses of steel concrete beams

Approximation solution for steel concrete beam accounting high-order shear deformation using trigonometric-series

Steel concrete beams have a reasonable structure in terms of using material and high load carrying capacity. This paper deals with an approximate solution based on a trigonometric series for the static of steel concrete beams. The displacement field is based on the higher-order theory using Reddy’s hypothesis. The governing equations are derived from variation principles. An approximate solution based on the representation of displacement fields by trigonometric series is developed to solve the static problem of steel concrete beams. In order to verify the accuracy of the present approximate solution, numerical results are compared with those of exact solutions using classical beam theory. The displacements and nominal stress distributions in the depth direction are obtained with various high of beams. The present approximate approach can accurately predict the displacements and stresses of steel concrete beams

The relation between university GPA and family background: Evidence from a university in Vietnam

Based on three data sets of information on students of a university in Vietnam, we estimate the factors affecting GPA by using the two-stage least squares (2SLS) method. The results of estimation highlight that parents’ occupation as farmers and living location in rural areas have an adverse impact on the GPA of students at university (University GPA). Causally, the government does not control or monitor the hours of part-time work of students earning a living cost and tuition fee, which rise dynamically in city located the university. Furthermore, we also find a positive relation between national university entrance point and the university GPA

Damage detection for a cable-stayed Bridge under the effect of moving loads using Transmissibility and Artificial Neural Network

Artificial Neural Network (ANN) has been widely used for Structural Health Monitoring (SHM) in the last decades. To detect damage in the structure, ANN often uses input data consisting of natural frequencies or mode shapes. However, this data is not sensitive enough to accurately identify minor structural defects. Therefore, in this study, we propose to use transmissibility to generate input data for the input layer of ANN. Transmissibility uses output signals exclusively to preserve structural dynamic properties and is sensitive to damage characteristics. To evaluate the efficiency of the proposed approach, a cable-stayed bridge with a wide variety of damage scenarios is employed. The results show that the combination of transmissibility and ANN not only accurately detect damages but also outperforms natural frequencies-based ANN in terms of accuracy and computational cost