Abstract: A system for quickly locating and retrieving flight data of an aircraft after an aircraft mid-air mishap comprises: a flight data recorder; a tracking device comprising at least one camera; a rapid ejection system for ejecting the flight data recorder and tracking device; a soft landing system; and a tow system, wherein the tow system is configured to continue to transmit flight information from the aircraft to the tracking device via the data communication link for a period of time after the ejection of the tracking device; and wherein the tracking device transmits to the flight data recorder the flight information received from the aircraft after ejection and the images captured by the tracking device immediately following the mid-air mishap, and wherein the flight data recorder is configured to in turn transmit said flight information and images to the remote device.

Abstract: We investigate crack formation in deposition films from drying colloidal suspension drops, by varying the roughness and texture of the substrate. The experimental results indicate that the crack number or crack spacing presents a general dependence on the substrate roughness, despite the orientation of the substrate textures. Interestingly, the crack spacing decreases with the increase of the roughness. Two possible mechanisms are proposed to understand the dependence of the cracks on roughness. Firstly, the concentration reduction of the drying suspension due to collecting colloidal particles from the substrate textures decreases the crack spacing. Secondly, stress concentration resulting from the defects (the notches in textures) in the dried deposition enhances crack formation. However, a quantitative estimation by the calculation of the stress concentrating factors reveals that the notch of the substrate textures dominates crack variation. The results here bring forth a practical method for controlling the crack orientation and suppression, and a potential application to crack-free coatings, films and paintings during the drying of complex fluids.

Abstract: This paper reports a self-powered WSN system based on piezoelectric energy harvesting and used for aircraft health monitoring. The system consists of three main subsystems, energy harvesting unit, MCU & wireless transceiver unit, and sensors unit. The prototype has dimension of 138 mm (L) × 41 mm (W) × 23 mm (H) with a weight of only 40 grams, making it easily integrated and implemented in an aircraft environment. Simulation results showed that with an excitation of 40 Hz frequency and 0.5 g acceleration on the harvester, the system takes about 3.4 secs to power the system with a selected voltage and another 23 secs to perform the initialization operations of the system. After the initialization, data are measured and transmitted wirelessly with a total energy consumption of 0.65 mJ in one cycle every one second. In addition, a new power management strategy for the applications using capacitors to store harvested energy was proposed. The mechanism relies on the analysis of how much energy has been stored on capacitor to determine the executions of the operations in the system. A novel energy saving interface (ESI) is designed to minimize the power consumption during the voltage measurement and an intelligent algorithm was developed to implement the strategy. Initial experiments show that the adapted Z-Stack and the proposed algorithm can be implemented on the system designed in this paper.

Abstract: A method based on the Euler equations is proposed for solving transonic flutter problems. The transonic nonlinear flow field with local shock wave/boundary layer interaction is obtained by the Euler/boundary layer equations, and the aerodynamic forces are converted from the time domain to the frequency domain using system identification techniques. The structural dynamic equations in generalized coordinates are adopted for solving structure problems. The method is validated by a flutter boundary prediction of the AGARD 445.6 wing model. The simulation results show that the method presented in this paper is accurate for the prediction of transonic flutter boundary through comparison with experimental data and other simulation results. Furthermore, the present frequency domain method is also much more efficient than the time domain method.

Abstract: Debonding is one of the most dangerous damages in honeycomb sandwich structures, which causes stiffness reduction and is invisible from the surface Guided wave-based non-destructive evaluation is a promising approach with high sensitivity and high efficiency for debonding detection A torsional guided wave method is proposed to inspect debonding damage in honeycomb sandwich beams, which is proved to be better in damage location for the beams in the paper than the flexural wave used before The honeycomb heterogeneity effect on the interaction between guided waves and debonding are first investigated by finite element methods Then the ability of torsional waves to determine debonding locations and sizes is discussed in detail Finally, in order to verify the proposed method, experiments are carried out to inspect debonding damage with two sizes

Abstract: A new study shows that a moving contact line could be more dangerous for a hydrophobic coating layer on a surface than lamellar flow. The tiny water drops generate a driving force that removes the coating molecules, collecting and depositing them on the substrate as the contact line recedes.

Abstract: The damage introduced by low-velocity impact is a threat to adhesively bonded composite joints. The impact response and tensile behaviors after impact of composite scarf joints was investigated using experimental and finite element analysis techniques. 18 specimens were impacted in three different locations and tensile tests after impact were conducted. The test results demonstrated that when impacted on the back face of scarf tip, the average dent depth was largest and the average tensile strength after impact was lowest. When impacted in the middle of the bondline slope, the dent depth was smallest and the tensile strength after impact was highest. When impacted on the front face of scarf tip, the dent depth and the tensile strength after impact was mediate. Stress concentration was observed in the scarf tips and areas beside the impact location because of the influence of bending stress and bypass load. The finite element analysis results showed that the extensive expand of fiber damage and adhesive damage lead to catastrophic failure of the whole structure.

Abstract: The current RANS models are generally established and calibrated under incompressible condition and these kinds of models could succeed in predicting many features of incompressible flows. However, these models extended to the high-speed, compressible flows are always less accurate. In the paper, a compressible von Karman length scale is proposed for compressible flows considering the variable densities. It contains no empirical coefficients and is based on phenomenological theory. In the turbulent kinetic equation, the extra unclosed terms induced by non-constant densities are treated as dissipation terms and the equation is closed algebraically via the introduction of the von Karman length scale. The original and the proposed von Karman length scale lead to two different kinds of SAS (scale adaption simulation) models, KDO (turbulence kinetic energy dependent only) and CKDO (compressible KDO), respectively. Compressible mixing layer with significant compressibility is studied within standard k–ϵ...

Abstract: In this paper we offer an explanation for why regional jets are less used in emerging economies by using a real options valuation (ROV) approach. Our ROV analysis is based on the observation that airlines are operating under different development and regulatory environments between emerging economies and developed economies. We quantify the values of the options using a case study of aircraft acquisition by airlines in the US, Brazil and China. It is found that although a theoretical value gap (a negative ROV) exists between narrow-body aircraft and regional jets (e.g., between A320 and E190) for the US carrier that operates in the condition of a low initial passenger volume per trip and a low passenger growth rate, the gap will be weaken and even become a positive ROV for the Brazilian and Chinese carriers facing a high growth rate. Furthermore, regulatory restrictions faced by Chinese carriers have a positive influence on the ROV that is biased towards narrowbody aircraft over regional jets, although this influence is less than the positive ROV impact from the high growth rate. The managerial and policy implications are also discussed.

Abstract: This paper presents an improved quantum behaved particle swarm optimization (IQPSO) algorithm to identify the robot kinematics parameter errors to improve the absolute accuracy of serial robots. The IQPSO algorithm is based on the quantum behaved particle swarm optimization (QPSO) algorithm. To improve the convergence speed, in the IQPSO algorithm, each dimension of the global best position is kept to be the best at each iterative process by comparing each dimension with the pre-value in the last iterative process. Comparing the IQPSO algorithm with least squared algorithm, the absolute accuracy of the robot can be improved 200 %. And compared with the standard particle swarm optimization (SPSO) algorithm and QPSO algorithm, the convergence speed is improved about 200 %. So the proposed algorithm can effectively identify the robot kinematics parameter errors.

Abstract: For aircraft complex systems such as auxiliary power unit (APU), the performance evaluation is currently restricted to observation of several typical parameters. Many other monitoring parameters recorded in Quick Access Recorder (QAR) reflect the APU condition from various aspects yet without enough attention. This study intends to propose integrated performance indicators through feature extraction among many monitoring parameters. Clustering analysis is then conducted to validate the effectiveness of the method by anomaly identification. This method has the potential to easily evaluate performance of some complex aircraft systems for early warning and prevent degradation from early stage.

Abstract: The influence of different coating formulas and times on the water and oil resistance of paperboard was studied. The water and oil resistance of paperboard coated with a modified butadiene-styrene copolymer latex and fluorinated anion grease-proof agent was better than that coated with modified butadiene-styrene copolymer latex, where the modified butadiene-styrene copolymer latex was used as the pre-coating substrate and the F1516 fluorinated grease-proof agent was used as the top coating material. By coating modified butadiene-styrene copolymer latex with 30% solid content and F1516 fluorinated grease-proof agent with 24% solid content, the oil resistance of paperboard could reach anti-oil grade 12 and the water resistance could increased by 98.64% (compared with the base paperboard without any coating treatment).

Abstract: Dynamic load of helicopter rotors due to gust directly affects the structural stress and flight performance for helicopters. Based on a large deflection beam theory, an aeroelastic model for isolated helicopter rotors in the time domain is constructed. The dynamic response and structural load for a rotor under the impulse gust and slope-shape gust are calculated, respectively. First, a nonlinear Euler beam model with 36 degrees-of-freedoms per element is applied to depict the structural dynamics for an isolated rotor. The generalized dynamic wake model and Leishman-Beddoes dynamic stall model are applied to calculate the nonlinear unsteady aerodynamic forces on rotors. Then, we transformed the differential aeroelastic governing equation to an algebraic one. Hence, the widely used Newton-Raphson iteration algorithm is employed to simulate the dynamic gust load. An isolated helicopter rotor with four blades is studied to validate the structural model and the aeroelastic model. The modal frequencies based on the Euler beam model agree well with published ones by CAMRAD. The flap deflection due to impulse gust with the speed of 2m/s increases twice to the one without gust. In this numerical example, results indicate that the bending moment at the blade root is alleviated due to elastic effect.

Abstract: The tensile and compression strength of the Z shaped stiffened-welded plate is studied in this paper. Through the analysis of the main influential factors of the panel strength, the theoretical calculation formula of the tensile and compression strength of the panel plate which are verified by the experimental values is established in this paper,. And the tensile strength prediction value is 8.4% larger than the experimental value while the compression strength prediction value is 4.36% smaller than the experimental value. This method can provide reference for the selection of welding structure.

Abstract: A new algorithm is proposed in this paper to solve the problem of multisource distance measurement equipment (DME) pulse interference suppression for global positioning system (GPS) L5 signal. The problem can be treated as DME signal estimation, and then can be taken as a problem of optimization. Based on nonlinear least squares (NLS) criterion, using WRELAX iteration method, the optimization problem can be solved to estimate the multisource DME signal. Once DME pulse interference signal is estimated, then it can be reconstructed, and finally can be eliminated and suppressed. Compared with traditional method, the proposed method can reserve more useful GPS satellite data. The performance of proposed method is verified by numerical simulations.

Abstract: L5 signal is set up for civil aviation exclusively in GPS (Global Positioning System), and takes up exclusive frequency band. However, the DME (Distance Measurement Equipment) signal which has already applied for distance measurement works as the same frequency band as GPS L5. DME signal with high power will decrease SINR (Signal to Interference and Noise Ratio) of GPS L5 and even give rise to acquisition failure. On DME interference suppression, the traditional methods will bring loss to useful satellite data. Thus the performance of GPS L5 receiver will suffer from serious degradation. In the light of the received signal model, a new DME interference mitigation algorithm is presented in this paper. Firstly, frequency is estimated with time-modulated windowed all-phase DFT (tmwapDFT). Then, we use the estimated frequency to get amplitude and signal delay information with signal separation estimation theory. Compared with traditional method, the proposed method can reserve more useful satellite data. The performance of proposed method is verified by simulations.

Abstract: The wind tunnel test for a scaled airframe model normally can not obtain the high frequency components when transform the scaled model to full scale. Meanwhile, due to the limitation of the acoustic wind tunnel facilities, the measurement can not perform a full acoustic directivity covering from 0 to 180°. In order to extend the frequency and polar angle information acquired by wind tunnel test results, a method for extrapolation of frequency and directivity of a 1:7.6 scaled full airframe wind tunnel test data is developed. The entire sound pressure spectrum is decomposed into two segments: low frequency segment and mid-high frequency segment. Each segment is fitted by a spectrum envelope with different slopes generated from flight test spectrums. An auto regressive model (AR model) is also developed and applied to extrapolate the acoustic directivity in this paper.

Abstract: Landing gear noise can be significant at aircraft approach. It is difficult to quantify the landing gear noise during a flight test. The motivation of this work is to develop a feasible method with acoustic wind tunnel test to predict the in-flight landing gear noise. The prediction is based on an empirical model (Guo 2006) calibrated by wind tunnel test. The wind tunnel test was conducted on a 1:7.6 scale model of an airframe. The calibration of the empirical model and the wind tunnel test focuses on the installation effects that include interaction with flap and the local flow velocity in the existing empirical model. The installation effect on the far-field directivity factor is investigated by the experimental studies. The mean flow patterns of the wing with deployed slat and flap at approach configuration are calculated by CFD solver ANSYS. After validation of the empirical model, the result of the scale model is transposed to the full scale landing gear noise in the flight condition.

Abstract: In this paper, fatigue crack growth and delamination behaviours of a new fibre metal laminate (FML) named as Al-Li alloy laminate were tested under different single tensile overloads and compared with those of glass laminate aluminium reinforced epoxy. The results indicate that the crack growth rate of Al-Li alloy laminate after overload applied can quickly get back to its original level when the crack grows outside of the overload plastic zone. The overload has no influence on the delamination shape and size of Al-Li alloy laminate. These results are obviously different from those found in the present study for GLARE, in which the crack growth rate cannot recover after overload, even though the crack is far beyond the overload plastic zone. A kink nearby the location of overload applied was found in the obtained delamination shape. This study provides some new results for better understanding the damage tolerance mechanism of FMLs.

Abstract: The research of adsorption theory has recently gained renewed attention due to its critical relevance to a number of trending industrial applications, hydrogen storage and shale gas exploration for instance. The existing theoretical foundation, laid mostly in the early twentieth century, was largely based on simple heuristic molecular interaction models and static interaction potential which, although being insightful in illuminating the fundamental mechanisms, are insufficient for computations with realistic adsorbent structure and adsorbate hydrodynamics, both critical for real-life applications. Here we present and validate a novel lattice Boltzmann model incorporating both adsorbate-adsorbate and adsorbate-adsorbent interactions with hydrodynamics which, for the first time, allows adsorption to be computed with real-life details. Connection with the classic Ono-Kondo lattice theory is established and various adsorption isotherms, both within and beyond the IUPAC classification are observed as a pseudo-potential is varied. This new approach not only enables an important physical to be simulated for real-life applications, but also provides an enabling theoretical framework within which the fundamentals of adsorption can be studied.