Showing papers by "Vaughn College of Aeronautics and Technology published in 2017"
TL;DR: The goal of the developed algorithm is to obtain an optimal transmission map as well as to remove hazes from a single input image to solve the problem of fog cover, and the method preserves the natural appearance of the image.
Abstract: Fog cover is generally present in outdoor scenes, which limits the potential for efficient information extraction from images. In this paper, the goal of the developed algorithm is to obtain an optimal transmission map as well as to remove hazes from a single input image. To solve the problem, we meticulously analyze the optical model and recast the initial transmission map under an additional boundary prior. For better preservation of the results, the difference-structure-preservation dictionary could be learned, such that the local consistency features of the transmission map could be well preserved after coefficient shrinkage. Experimental results show that the method preserves the natural appearance of the image.
69 citations
TL;DR: In this article, a sort of W/Cr co-doped Bi4Ti3O12 ceramics with different additional amount of Cr2O3: Bi4 Ti2.95W0.05O12.
51 citations
Osaka University1, California Institute of Technology2, University of Notre Dame3, Goddard Space Flight Center4, Ohio State University5, Niels Bohr Institute6, Heidelberg University7, Massey University8, Tsinghua University9, Zhejiang University10, University of Auckland11, Nagoya University12, Vaughn College of Aeronautics and Technology13, Victoria University of Wellington14, Kyoto Sangyo University15, Centre national de la recherche scientifique16, University of Tasmania17, Tel Aviv University18, European Southern Observatory19, University of Salerno20, Ames Research Center21, University of Toulouse22, Las Cumbres Observatory Global Telescope Network23, University of St Andrews24, Vision Institute25, Open University26, INAF27, Qatar Airways28
TL;DR: In this article, the authors reported the discovery of a microlensing planet, MOA-2016-BLG-227Lb, with a large planet/host mass ratio of q ≃ 9 × 10^(−3).
Abstract: We report the discovery of a microlensing planet—MOA-2016-BLG-227Lb—with a large planet/host mass ratio of q ≃ 9 × 10^(−3). This event was located near the K2 Campaign 9 field that was observed by a large number of telescopes. As a result, the event was in the microlensing survey area of a number of these telescopes, and this enabled good coverage of the planetary light-curve signal. High angular resolution adaptive optics images from the Keck telescope reveal excess flux at the position of the source above the flux of the source star, as indicated by the light-curve model. This excess flux could be due to the lens star, but it could also be due to a companion to the source or lens star, or even an unrelated star. We consider all these possibilities in a Bayesian analysis in the context of a standard Galactic model. Our analysis indicates that it is unlikely that a large fraction of the excess flux comes from the lens, unless solar-type stars are much more likely to host planets of this mass ratio than lower mass stars. We recommend that a method similar to the one developed in this paper be used for other events with high angular resolution follow-up observations when the follow-up observations are insufficient to measure the lens–source relative proper motion.
49 citations
Korea Astronomy and Space Science Institute1, Harvard University2, University of Warsaw3, Massey University4, California Institute of Technology5, Zhejiang University6, Tsinghua University7, University of St Andrews8, European Southern Observatory9, University of Copenhagen10, Ohio State University11, University of Toronto12, Massachusetts Institute of Technology13, University of Canterbury14, Korea University of Science and Technology15, Max Planck Society16, Chungbuk National University17, Kyung Hee University18, University of Salerno19, Nagoya University20, Goddard Space Flight Center21, University of Auckland22, Osaka University23, Vaughn College of Aeronautics and Technology24, Victoria University of Wellington25, Japan Aerospace Exploration Agency26, Kyoto Sangyo University27, Ames Research Center28, Vanderbilt University29, University of Manchester30, Chinese Academy of Sciences31, University of Toulouse32, Las Cumbres Observatory Global Telescope Network33, Heidelberg University34, Institut d'Astrophysique de Paris35, Tel Aviv University36, Open University37, Liverpool John Moores University38, Istituto Nazionale di Fisica Nucleare39, University of Hamburg40, Stockholm University41, INAF42, Keele University43, University of Antofagasta44, Pontifical Catholic University of Chile45, Sharif University of Technology46, Isfahan University of Technology47, Aarhus University48
TL;DR: The OGLE-2016-BLG-1190Lb is the first Spitzer microlensing planet in the Galactic bulge/bar, an assignation that can be confirmed by two epochs of high-resolution imaging of the combined source-lens baseline object as discussed by the authors.
Abstract: We report the discovery of OGLE-2016-BLG-1190Lb, which is likely to be the first Spitzer microlensing planet in the Galactic bulge/bar, an assignation that can be confirmed by two epochs of high-resolution imaging of the combined source–lens baseline object. The planet's mass, M p = 13.4 ± 0.9 M J , places it right at the deuterium-burning limit, i.e., the conventional boundary between "planets" and "brown dwarfs." Its existence raises the question of whether such objects are really "planets" (formed within the disks of their hosts) or "failed stars" (low-mass objects formed by gas fragmentation). This question may ultimately be addressed by comparing disk and bulge/bar planets, which is a goal of the Spitzer microlens program. The host is a G dwarf, M host = 0.89 ± 0.07 M ⊙, and the planet has a semimajor axis a ~ 2.0 au. We use Kepler K2 Campaign 9 microlensing data to break the lens-mass degeneracy that generically impacts parallax solutions from Earth–Spitzer observations alone, which is the first successful application of this approach. The microlensing data, derived primarily from near-continuous, ultradense survey observations from OGLE, MOA, and three KMTNet telescopes, contain more orbital information than for any previous microlensing planet, but not quite enough to accurately specify the full orbit. However, these data do permit the first rigorous test of microlensing orbital-motion measurements, which are typically derived from data taken over <1% of an orbital period.
39 citations
TL;DR: In this paper, generalized stochastic resonance (GSR) was investigated in a fractional harmonic oscillator with time delay and fluctuation damping, and the analytical expression of the output amplitude gain was derived by applying small delay approximation and stochastically averaging.
Abstract: We investigate generalized stochastic resonance (GSR) in a fractional harmonic oscillator with time delay and fluctuation damping. Considering that nonlinear noise widely exists in actual systems compared with linear noise, the fluctuation of damping is modeled as polynomial trichotomous noise. The analytical expression of the output amplitude gain is derived by applying small delay approximation and stochastic averaging. Simulation results show that the output amplitude gain curves, as functions of time delay versus noise parameters, behave non-monotonically and exhibit typical GSR. Furthermore, nonlinear phenomena of stochastic multi-resonance with two, three, and four peaks are observed. Finally, we provide the phase diagrams for GSR versus time delay with different system parameters. Furthermore, the mechanism underlying the stochastic multi-resonance with two, three, and four peaks, as well as their connections, is elucidated. This study could serve as a theoretical basis for the practical use and control of GSR in future works.
29 citations
TL;DR: In this article, the porosity is a key property that plays a crucial role in enhancing the performance of solid oxide fuel cell (SOFC) electrodes, and the addition of pyrolyzable pore-formers to the electrode materials of SOFCs can generate suitable porous microstructures with the required porosity, pore sizes, and morphology.
26 citations
TL;DR: In this paper, an effective three dimensional thermal-electrical coupling analysis finite element model of composite laminate suffered from lightning current was established based on ABAQUS, to elucidate the effects of lighting current waveform parameters and thermal/electrical properties on the extent of ablation damage.
Abstract: According to the mathematical analysis model constructed on the basis of energy-balance relationship in lightning strike, and accompany with the simplified calculation strategy of composite resin pyrolysis degree dependent electrical conductivity, an effective three dimensional thermal-electrical coupling analysis finite element model of composite laminate suffered from lightning current was established based on ABAQUS, to elucidate the effects of lighting current waveform parameters and thermal/electrical properties of composite laminate on the extent of ablation damage. Simulated predictions agree well with the composite lightning strike directed effect experimental data, illustrating the potential accuracy of the constructed model. The analytical results revealed that extent of composite lightning strike ablation damage can be characterized by action integral validly, there exist remarkable power function relationships between action integral and visual damage area, projected damage area, maximum damage depth and damage volume of ablation damage, and enhancing the electrical conductivity and specific heat of composite, ablation damage will be descended obviously, power function relationships also exist between electrical conductivity, specific heat and ablation damage, however, the impact of thermal conductivity on the extent of ablation damage is not notable. The conclusions obtained provide some guidance for composite anti-lightning strike structure-function integration design.
26 citations
TL;DR: In this paper, a sequential dip-coating coupled with co-firing process was developed to fabricate anode-supported microtubular solid oxide fuel cells (MT-SOFCs) using carbon rods as a sacrificial template.
23 citations
TL;DR: A novel dehazing approach based on a local consistent Markov random field framework, which effectively improves the image quality captured by the CMOS image sensor and has the combined advantages of detail recovery and color preservation.
Abstract: The CMOS (Complementary Metal-Oxide-Semiconductor) is a new type of solid image sensor device widely used in object tracking, object recognition, intelligent navigation fields, and so on. However, images captured by outdoor CMOS sensor devices are usually affected by suspended atmospheric particles (such as haze), causing a reduction in image contrast, color distortion problems, and so on. In view of this, we propose a novel dehazing approach based on a local consistent Markov random field (MRF) framework. The neighboring clique in traditional MRF is extended to the non-neighboring clique, which is defined on local consistent blocks based on two clues, where both the atmospheric light and transmission map satisfy the character of local consistency. In this framework, our model can strengthen the restriction of the whole image while incorporating more sophisticated statistical priors, resulting in more expressive power of modeling, thus, solving inadequate detail recovery effectively and alleviating color distortion. Moreover, the local consistent MRF framework can obtain details while maintaining better results for dehazing, which effectively improves the image quality captured by the CMOS image sensor. Experimental results verified that the method proposed has the combined advantages of detail recovery and color preservation.
20 citations
Chungbuk National University1, University of Warsaw2, Korea Astronomy and Space Science Institute3, Max Planck Society4, Ohio State University5, Massey University6, University of Canterbury7, Korea University of Science and Technology8, Smithsonian Astrophysical Observatory9, Kyung Hee University10, Nagoya University11, Goddard Space Flight Center12, University of Notre Dame13, University of Auckland14, Osaka University15, Vaughn College of Aeronautics and Technology16, Victoria University of Wellington17, Japan Aerospace Exploration Agency18, Kyoto Sangyo University19
17 citations
TL;DR: In this paper, a coupled thermal-electrical model constructed is capable to simulate the ablation damage for carbon woven fabric/epoxy laminates exposed to simulated lightning current through experimental verification.
Abstract: To clarify the evolution of damage for typical carbon woven fabric/epoxy laminates exposed to lightning strike, artificial lightning testing on carbon woven fabric/epoxy laminates were conducted, damage was assessed using visual inspection and damage peeling approaches. Relationships between damage size and action integral were also elucidated. Results showed that damage appearance of carbon woven fabric/epoxy laminate presents circular distribution, and center of the circle located at the lightning attachment point approximately, there exist no damage projected area dislocations for different layers, visual damage territory represents maximum damage scope; visible damage can be categorized into five modes: resin ablation, fiber fracture and sublimation, delamination, ablation scallops and block-shaped ply-lift; delamination damage due to resin pyrolysis and internal pressure exist obvious distinguish; project area of total damage is linear with action integral for the same type specimens, that of resin ablation damage is linear with action integral, but no correlation with specimen type, for all specimens, damage depth is linear with logarithm of action integral. The coupled thermal–electrical model constructed is capable to simulate the ablation damage for carbon woven fabric/epoxy laminates exposed to simulated lightning current through experimental verification.
TL;DR: Simulation results demonstrate that the output SNR, as a function of system parameter, shows the different generalized SR behaviors in the case of various internal parameters of driving chirp signal and external parameters of the moving target.
Osaka University1, University of Warsaw2, Goddard Space Flight Center3, University of Notre Dame4, Massey University5, University of Auckland6, Nagoya University7, Vaughn College of Aeronautics and Technology8, Victoria University of Wellington9, University of Canterbury10, Kyoto Sangyo University11, Ohio State University12, University of Warwick13
TL;DR: The OGLE-2013-BLG-1761 microlensing event was reported in this article, where a super-Jupiter mass planet with a mass of m(sub p) = 2.7(+ 2.9) was orbited by an M/K dwarf with amass of M(sub L) = 0.33(+ 0.32-1.5)
Abstract: We report the discovery and the analysis of the planetary microlensing event, OGLE-2013-BLG-1761. There are some degenerate solutions in this event because the planetary anomaly is only sparsely sampled. However, the detailed light curve analysis ruled out all stellar binary models and shows the lens to be a planetary system. There is the so-called close wide degeneracy in the solutions with the planet host mass ratio of q approx.(7.0+/-2.0) x 10(exp -3) and q approx.(8.1+/-2.6) x 10(exp -3) with the projected separation in Einstein radius units of s = 0.95 (close) and s = 1.18(wide), respectively. The microlens parallax effect is not detected, but the finite source effect is detected. Our Bayesian analysis indicates that the lens system is located -D(sub L) = 6.9(+ 1.0 -1.2)kpc away from us and the host star is an M/K dwarf with amass of M(sub L) = 0.33(+ 0.32- 1.9)Stellar Mass orbited by a super-Jupiter mass planet with a mass of m(sub p) = 2.7(+ 2.5 - 1.5) M(sub Jup) at the projected separation of a(sub l) = 1.8(+ 0.5 -0.5)au. The preference of the large lens distance in the Bayesian analysis is due to the relatively large observed source star radius. The distance and other physical parameters may be constrained by the future high-resolution imaging by large ground telescopes or HST. If the estimated lens distance is correct, then this planet provides another sample for testing the claimed deficit of planets in the Galactic bulge.
TL;DR: In this article, the elastic-plastic deformation behaviors of nano-grained and coarsegrained yttrium aluminum garnet (YAG) transparent ceramics are investigated using nanoindentation.
Abstract: The elastic-plastic deformation behaviors of nano-grained and coarse-grained yttrium aluminum garnet (YAG) transparent ceramics are investigated using nanoindentation. An inverse Hall-Petch relation is observed for the nano-grained YAG ceramic and a forward Hall-Petch relation is observed for the coarse-grained YAG ceramic. In addition, the plastic work ratio as a function of applied load for the nano-grained YAG ceramic shows a different trend than that for the coarse-grained YAG ceramic. These observations suggest that the plastic deformation of the nano-grained YAG ceramic cannot be attributed to the normal dislocation mechanism and is controlled by grain boundary sliding. A generalized self-consistent model for studying the mechanical behavior of the nano-grained YAG ceramic is developed and validated by experimental results. The stress-strain relationship predicted by this model is embedded in finite element simulations which confirmed that the plastic deformation of the nano-grained YAG ceramic indeed can be attributed to grain boundary sliding.
Goddard Space Flight Center1, University of Notre Dame2, Massey University3, Nagoya University4, University of Auckland5, Osaka University6, Vaughn College of Aeronautics and Technology7, Victoria University of Wellington8, Japan Aerospace Exploration Agency9, University of Canterbury10, Kyoto Sangyo University11
Tsinghua University1, Ohio State University2, Massey University3, Korea Astronomy and Space Science Institute4, Max Planck Society5, University of Warsaw6, Osaka University7, University of Salerno8, Goddard Space Flight Center9, Vision Institute10, Smithsonian Astrophysical Observatory11, Chungbuk National University12, Nagoya University13, University of Notre Dame14, University of Auckland15, Vaughn College of Aeronautics and Technology16, Victoria University of Wellington17, Japan Aerospace Exploration Agency18, University of Canterbury19, Kyoto Sangyo University20, California Institute of Technology21, Korea University of Science and Technology22, Kyung Hee University23, Las Cumbres Observatory Global Telescope Network24, Heidelberg University25, Qatar Airways26, University of St Andrews27, Open University28, Liverpool John Moores University29
TL;DR: The analysis of the binary gravitational microlensing event MOA-2015-BLG-020 is presented in this article, where the light curve deviates significantly from the lensing model that is based on the rectilinear lens-source relative motion.
Abstract: We present the analysis of the binary gravitational microlensing event MOA-2015-BLG-020. The event has a fairly long timescale (~63 days) and thus the light curve deviates significantly from the lensing model that is based on the rectilinear lens-source relative motion. This enables us to measure the microlensing parallax through the annual parallax effect. The microlensing parallax parameters constrained by the ground-based data are confirmed by the Spitzer observations through the satellite parallax method. By additionally measuring the angular Einstein radius from the analysis of the resolved caustic crossing, the physical parameters of the lens are determined. It is found that the binary lens is composed of two dwarf stars with masses M_1 = 0.606 ± 0.028 M⊙ and M_2 = 0.125 ± 0.006 M⊙ in the Galactic disk. Assuming that the source star is at the same distance as the bulge red clump stars, we find the lens is at a distance D_L = 2.44 ± 0.10 kpc. We also provide a summary and short discussion of all of the published microlensing events in which the annual parallax effect is confirmed by other independent observations.
TL;DR: In this article, an RUL prediction method based on the consistency test of a Wiener process is proposed, and the validity of the presented method is verified by accurate computation results of real data, which provides a theoretical and practical guidance for engineers to predict the RUL of equipment after maintenance.
TL;DR: In this article, the authors presented a theoretic implementation method of morphing a UAV to fly in the air and submerge in the water, considering the tremendous differences between hydrodynamic configuration and aerodynamic configuration of a vehicle.
Abstract: This paper presents a theoretic implementation method of Morphing Unmanned Submersible Aerial Vehicle (MUSAV), which can both submerge in the water and fly in the air. Two different shapes are put forward so that the vehicle can suit both submergence and flight, considering the tremendous differences between hydrodynamic configuration and aerodynamic configuration of a vehicle. The transition of the two shapes can be achieved by using morphing technology. The water-to-air process, including water-exit, morphing, take-off and steady flight, is analyzed. The hydrodynamic and aerodynamic model of the vehicle exiting the water surface obliquely and then taking off into the air has been founded. The control strategy after morphing is analyzed and the control method is given. Numerical method is used to validate the motion model of the water-exit process. Results of simulations show the validity of the proposed model and the feasibility of MUSAV in theory.
TL;DR: In this paper, a generalized Langevin equation with Mittag-Leffler friction kernel was used for modeling anomalous diffusion processes with long-memory and long-range dependence.
Abstract: The resonant behavior of a generalized Langevin equation (GLE) in the presence of a Mittag-Leffler noise is studied analytically in this paper. Considering that a GLE with a Mittag-Leffler friction kernel is very useful for modeling anomalous diffusion processes with long-memory and long-range dependence, and the surrounding molecules do not only collide with the Brownian particle but also adhere to the Brownian particle for random time. Thus, we consider the Brownian particle with fluctuating mass, and the fluctuations of the mass are modelled as a dichotomous noise. Applying the stochastic averaging method, we obtain the exact expression of the output amplitude gain of the system. By studying the impact of the driving frequency and the noise parameters, we find the non-monotonic behaviors of the output amplitude gain. The results indicate that the bona fide SR, the wide sense SR and the conventional SR phenomena occur in the proposed harmonic oscillator with fluctuating mass driven by Mittag-Leffler noise. It is found that when we consider the output amplitude gain versus the driving frequency, the phenomena of stochastic multi-resonance (SMR) with two, three and four peaks are observed, and the quadruple-peaks SR phenomenon had never been observed in previous literature. Besides, when we investigate the dependence of output amplitude gain on the memory exponent, the inverse stochastic resonance (ISR) phenomenon takes place, in contrast to the well-known phenomenon of stochastic resonance. Furthermore, we compare the corresponding ordinary harmonic oscillator without memory to our generalized model, and found that the properties of long-memory and long-range dependence endows our generalized model with more abundant dynamic behaviors than the ordinary harmonic oscillator without memory.
TL;DR: In this article, a series of amorphous SiO 2 -Al 2 O 3 composites oxides with varying content of siO 2 were prepared by sol-gel method and used as the supports of Rh-based catalysts.
TL;DR: In this paper, the first-order moments of a linear fractional oscillator with random trichotomous mass and frequency were derived by using the Shapiro-Loginov formula and the Laplace transformation technique.
Abstract: The stochastic resonance (SR) phenomena of a linear fractional oscillator with random trichotomous mass and random trichotomous frequency are investigate in this paper. By using the Shapiro–Loginov formula and the Laplace transformation technique, the exact expression of the first-order moment of the system’s steady response is derived. The numerical results demonstrate that the evolution of the output amplitude is nonmonotonic with frequency of the periodic signal, noise parameters and fractional order. The generalized SR (GSR) phenomena, including single GSR (SGSR) and doubly GSR (DGSR), and trebly GSR (TGSR), are detected in this fractional system. Then, the GSR regions in the α − γ plane are determined through numerical calculations. In addition, the interaction effect of the multiplicative trichotomous noise and memory can diversify the stochastic multiresonance (SMR) phenomena, and induce reverse-resonance phenomena.
TL;DR: This technique can be used for the real-time measurement of the real loop gain in a closed PLL without breaking its locking state and the agreement of the measured loop gain and theoretical calculations proves the validity of this measurement technique.
Abstract: A simple and robust technique for directly measuring the loop gain and bandwidth of a phase-locked loop (PLL) is proposed. This technique can be used for the real-time measurement of the real loop gain in a closed PLL without breaking its locking state. The agreement of the measured loop gain and theoretical calculations proves the validity of the proposed measurement technique. This technique with a simple configuration can be easily expanded to other phase-locking systems whose loop gain and bandwidth should be measured precisely.
TL;DR: In this paper, static and tension-tension fatigue experiments were conducted on T800/MTM46 cross-ply composite laminates and the residual strength of survival specimens were determined.
Abstract: Static and tension–tension fatigue experiments were conducted on T800/MTM46 cross-ply composite laminates. Fatigue limit and residual strength of the survival specimens were determined. Failure mod...
01 Jul 2017
TL;DR: In this paper, the authors proposed a stealth-based multi-effectors distribution scheme for flying wing in which the radar cross section (RCS) of each control surface is calculated and analyzed.
Abstract: With regard to the objective of stealthy optimization in control surface deflection, the stealth-based multi-effectors distribution scheme is presented for flying wing in this paper. The radar cross section (RCS) of each control surface is calculated and analyzed. The stealthy efficiency data curves are obtained through comparing the deflection values with the normal state. Taking the objective of optimal stealthy performance into account, the weighted pseudo-inverse is achieved by equivalence transformation. Furthermore, the sequential quadratic programming (SQP) based control allocation is applied to get rid of actuator constraints. To validate the effectiveness of the proposed approach, the simulation on the flying wing indicates that the stealthy generated by control surfaces can be minimized by reasonable deflections.
TL;DR: The review discusses both physical theories and critical technologies in the bio-inspired microfluidics, from biomimetic design to real-world applications, so as to offer new ideas for the design and application of smart microfluids.
Abstract: Bio-inspired microfluidic systems can be obtained through multidisciplinary approaches by using bio-inspired structural and functional designs for the microfluidic devices. This review mainly focuses on the concept of bio-inspired microfluidics to improve the properties of microfluidic systems for breaking through the bottlenecks of the current microfluidic devices, such as anti-fouling, smart, and dynamic response inside the microchannels under different environments. In addition, here, we show the current research progress of bio-inspired microfluidic systems in applications related to anti-fouling and smart devices, and biomedical research. The review discusses both physical theories and critical technologies in the bio-inspired microfluidics, from biomimetic design to real-world applications, so as to offer new ideas for the design and application of smart microfluidics, and the authors hope this review will inspire the active interest of many scientists in the area of the development and application ...
TL;DR: To improve the recognition probability of airborne infrared search and track systems (IRSTS) in air-to-air operations, the point target recognition probability model is established and the detection envelope is calculated for the airborne IRSTS.
Abstract: To improve the recognition probability of airborne infrared search and track systems (IRSTS) in air-to-air operations, the point target recognition probability model is established. And using an operating range model, the detection envelope is calculated for the airborne IRSTS. Combining with different operational backgrounds and specific technical parameters, the simulation results show that: (1) an increase in visual range and target speed, along with a decrease of oblique angle, produces an increase in the recognition probability; (2) the angle of maximum operating range of each detection envelope is the optimum detection point for the airborne IRSTS; and (3) the optimum threshold noise ratio is 8-10. These conclusions provide further scope in improving the operational effectiveness of airborne IRSTS in practical applications.
01 Jul 2017
TL;DR: In this paper, a generalized autoregressive conditional heteroskedastic model (GARCH) is proposed to model the degradation behavior of the solder joint under constant vibration loading, the voltage value at both sides of the Solder Joint is taken as the degradation characteristic.
Abstract: The degradation behavior of the solder joint under constant vibration loading is discussed, the voltage value at both sides of the solder joint is taken as the degradation characteristic. Considering the heteroskedasticity of characteristic signal under the vibration loading, the general time series model cannot describe heteroskedasticity, a Generalized Autoregressive Conditional Heteroskedastic model (GARCH) is proposed. Firstly, the upper and lower quantiles of the voltage signal are extracted. The failure time is determined by using the upper quantile and the degradation process is analyzed by the lower quantile. Secondly, the Auto-Regressive(AR) is built as the regressive basic model. Thirdly, a GARCH(1,1) model is proposed, which is tested by the Autoregressive Conditional Heteroskedastic (ARCH) method, the parameters of the model is estimated by the Maximum Likelihood algorithm. Finally, the performance of the presented GARCH based degradation model is examined by real data from experiment, which is compared with the classical AR model according to Akaike Information Criterion(AIC). The results suggest that GARCH(1,1) is superior to AR model, presented a theoretical foundation for further study about the degradation modeling of solder joint under vibration loading.
TL;DR: A wide range of computational methods including central scheme, MUSCL scheme, linear upwind scheme and Weighted Essentially Non Oscillatory (WENO) scheme have been applied in the current hybrid schemes framework.
Abstract: An idea of designing oscillation-less and high-resolution hybrid schemes is proposed and several types of hybrid schemes based on this idea are presented on block-structured grids. The general framework, for designing various types of hybrid schemes, is established using a Multi-dimensional Optimal Order Detection (MOOD) method proposed by Clain, Diot and Loubere [1]. The methodology utilizes low dissipation or dispersion but less robust schemes to update the solution and then implements robust and high resolution schemes to deal with problematic situations. A wide range of computational methods including central scheme, MUSCL scheme, linear upwind scheme and Weighted Essentially Non Oscillatory (WENO) scheme have been applied in the current hybrid schemes framework. Detailed numerical studies on classical test cases for the Euler system are performed, addressing the issues of the resolution and non-oscillatory property around the discontinuities.
01 Jul 2017
TL;DR: Simulation and experiments both show that the fuzzy immune PID algorithm based on the conventional PID controller has good dynamic and static performance, and it can effectively control the servo motor.
Abstract: Conventional parameter-not-adjustable PID controller has a poor dynamic response, and the output cannot follow the input quickly, accurately and stably when dealing with the uncertain parameters, non-linear, wide input system. Current mainstream self-turning algorithms are difficult to transplant to the embedded platform due to the large volume, real-time issue. A fuzzy immune PID algorithm based on the conventional PID controller is put forward to realize the self-tuning of the PID parameters following motor speed value. Against the proportional parameter, it is adjusted according to the mechanism of the human immune system, and its non-linear part is approximated by the fuzzy algorithm; Against the integral and derivative parameters, its self-adjustment is directly realized by the fuzzy algorithm. Finally, the validity of the whole algorithm is verified by using MATLAB / Simulink simulation platform. The hardware of the controller manufacture based on the STM32 produced by St semiconductor is completed and velocity tracking experiments are done. When the servo motor is given 60r/min and 360r/min speed inputs, the response time is within 130ms and the amount of overshoot is below 0.5%. In the case of external disturbance, the speed fluctuation value is within 0.2%. Then the controller is applied to full range chassis and succeeded in controlling it with high precision. Simulation and experiments both show that the controller has good dynamic and static performance, and it can effectively control the servo motor.
01 Jul 2017
TL;DR: In this article, a fusion approach based on adaptive regression (AR) and particle filter (PF) is put forward to predict the remaining life of high reliability and long life airborne fuel pump.
Abstract: In order to predict the remaining life of high reliability and long life airborne fuel pump, a fusion approach based on adaptive regression (AR) and particle filter (PF) is put forward. Firstly, the basic principles of adaptive regression algorithm and particle filter algorithm are introduced. Then, a fusion framework based on statistical prediction and data driven prediction is proposed. Secondly, taking into account the relationship between outlet pressure and performance degradation of airborne fuel pump, an AR model is used to establish the life degradation model of the airborne fuel pump. Finally, the RUL prediction of airborne fuel pump is realized by the fusion particle filter algorithm. The experimental results illustrate that compared to traditional regression approach, the proposed approach not only can effectively predict the life of airborne fuel pump, but also has the uncertainty expression of the prediction result.