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Abstract In this paper, a triangle matching method for geomagnetic navigation is developed, which aims at introducing as little redundant information as possible to improve the matching effect of regions with less magnetic information. According to the triangle similarity, the matching triangles are constructed on the isocline information corresponding to the trained BPNN geomagnetic map, and the best matching parameters can be obtained through the correcting function. Simulations based on uniform distribution and random distribution have been performed for the validation of the proposed algorithm. The anti-interference of the algorithm on noise is further demonstrated by comparing with the ICCP method using Monte Carlo simulation. [ABSTRACT FROM AUTHOR]

In this paper, a geomagnetic correcting navigation method is developed inspired by the simultaneous localization and mapping method, which can greatly improve the positioning precision, and helps to improve the mapping accuracy. The geomagnetic characteristic information on navigation path was analyzed during the navigation. The error models of simultaneous localization and mapping method combined with inertial navigation system were described to help developing Kalman filter. Simulations based on the actual geomagnetic reference map have been performed for the validation of the proposed algorithm. The method’s feasibility is further demonstrated by analysis of optimal segment length using Monte Carlo simulation. [ABSTRACT FROM AUTHOR]

We study quantum-mechanical diffusion master equation by comparison with the classical diffusion equation, and deduce how a pure coherent state evolves into a mixed state by diffusion both in classical way and in quantum mechanical way. [ABSTRACT FROM AUTHOR]

Using the polarimetric imaging sensor on LEO (Low-Earth Orbit) satellites to photograph the atmospheric polarization pattern derived from the polarized light backscattered by the atmospheric particles is proposed in this paper. First, the formation of polarization pattern and its measurement principle are introduced based on Rayleigh scattering, and the extraatmospheric polarization pattern is analyzed. Afterwards, it is presented that how to attain the geocentric vector and the solar vector simultaneously from the polarization pattern through the least squares method, which is verified by simulation subsequently. The simulation results show that it is feasible to derive the two vectors from the captured image. [ABSTRACT FROM AUTHOR]

It is put forward that solar vector can be obtained with polarization sensors in this paper, which plays an important role as a great clue of navigation. First, the design of the polarization sensor is introduced with the extraction method of azimuth angle from the polarization pattern. Then, it is advanced that solar vector can be attained through observing different directions using one or two polarization sensors. Consequently, an experiment is conducted and the results indicate that both algorithms of measuring solar vector are feasible. For the method of measuring solar vector with two polarization sensors, the accuracy of solar azimuth angle is 0.2°(1σ), and the accuracy of solar elevation angle is 0.4°(1σ) approximately. By contrast, the accuracy is relatively low for the method of using single polarization sensor. [ABSTRACT FROM AUTHOR]

This paper focuses on robust autopilot design for bank-to-turn (BTT) missiles by using adaptive dual-layer sliding mode control (ADSMC) under model uncertainties and external disturbances. This adaptive sliding mode scheme has a dual-layer structure. One layer drives the system reach the sliding surface in finite time, and the other minimizes the size of the control gains, whilst still guaranteeing the existence of a sliding motion. Therefore, the resulting adaptation law enables reducing the chattering magnitude compared with the traditional super-twisting method. The relationship between the gains and how to obtain them are also given in detail in this paper. Autopilot design progress for three channels is conducted and the closed-loop stability of bank-to-turn missile dynamics is guaranteed. Promising dynamic performance and strong robustness have been achieved for the bank-to-turn missile dynamics as shown in the simulation. [ABSTRACT FROM AUTHOR]

When using near-infrared (NIR) laser with wavelength around 1000 nm to weld Al alloys, the high laser reflectivity of Al alloys prevents most of the laser energy from participating in welding. While, the shorter wavelength laser can provide better absorption rate for Al alloys. The welding experiments of 6082 Al alloy using 455 nm wavelength blue laser and 1080 nm wavelength NIR laser were systematically studied. By analyzing the macroscopic morphology, infrared thermography, microstructure and mechanical properties of the welds, the special physical phenomenon of blue laser in the welding process, and the characteristics of two different wavelengths of laser welding 6082 alloy were studied. Results showed that the depth and width of weld welded by blue laser were greater than those welded by NIR laser. Meanwhile, the grains of the blue laser weld were fine, and the mechanical properties of the weld welded by blue laser was almost equal to that of NIR laser. Finally, the effects of different wavelengths of laser heat sources on the microstructure and mechanical properties of the joints were mainly studied. [ABSTRACT FROM AUTHOR]

In this paper, we develop a strictly convergent nonsingular terminal sliding mode guidance law for missiles with impact angle constraints. A novel nonsingular terminal sliding mode (NNTSM) control scheme is first proposed to improve the effectiveness of conventional terminal sliding mode in the whole phase plane, where the time taken to reach both the sliding surface and equilibrium point is guaranteed to be finite time. The proposed NNTSM control scheme is then applied to the guidance law of missiles with impact angle constraints, where extended state observer is designed to estimate the target acceleration. Simulation results are presented to validate the proposed guidance law. [ABSTRACT FROM AUTHOR]

Abstract: By virtue of operator ordering technique and the generating function of polynomials, we provide a simple and neat approach to studying operator identities and mathematical formulas regarding to two-variable Hermite polynomials, which differs from the existing mathematical ways. We not only derive some new integration formulas and summation relations about two-variable Hermite polynomial, but also draw a conclusion that two-variable Hermite polynomial excitation of two-mode squeezed vacuum state is a squeezed two-mode number state. This may open a new route of developing mathematics by virtue of the quantum mechanical representations and operator ordering technique. [Copyright &y& Elsevier]

Abstract: By virtue of the linear combination of a †and a and the coordinate-momentum intermediate representation as well as operator-ordering technique we derive some new expansion identities about Hermite-polynomial operators and Laguerre-polynomial operators. We also find a new approach for transiting the Hermite polynomial operator to the associated Laguerre polynomial operator. The reciprocal formula of the associated Laguerre polynomial is also derived. [Copyright &y& Elsevier]

Abstract: In Ref. by using the plane-wave representation of the fundamental Gaussian mode as a seed function, Enderlein and Pampaloni derived higher-order beam modes (Laguerre–Gaussian laser beams) of the electromagnetic field by acting with differential operators on this fundamental solution. In this paper we show that their approach can be improved by directly performing the integration with the aid of the two-variable Hermite polynomials, in so doing these modes can exhibit some new good characters. Their relationship to the eigenmodes of light propagation in the quadratic graded-index (GRIN) medium is pointed out. By introducing the two-mode entangled state representation the quantum states corresponding to these modes are also found which turns out to be the Hermite-polynomial excitation on the two-mode squeezed vacuum state. [Copyright &y& Elsevier]

Abstract: A multichannel double-polarization bandpass optical filter, which has the performance of variable channel interval, is theoretically proposed. The filter consists of a stack of two one-dimensional photonic crystals (1D PCs). Based on the resonant couple of evanescent waves localized at the interfaces between neighboring layers, the linear transmission properties of the filter are numerically simulated by the transfer matrix method. The simulation results show that channel number of the filter can be changed by varying the thickness of the middle layer in the centrosymmetric 1D PC structure, while the bandwidth and wavelength of the channel can be adjusted by the incident angle of light. This work may be helpful in designing multichannel double-polarization bandpass optical filter in optical communication systems. [Copyright &y& Elsevier]

By using the singular eigenvector (eigenket) of the creation operator a † we study how Dirac's inverse operators are squeezed and what is the normally ordered expansion of a † cosh λ + a sinh λ − 1 . We find the rule for converting annihilator's eigenket to creator's eigenket is: e z → e − ∂ ∂ z * δ ( z * ) , where δ ( z * ) is the Dirac's Delta function in contour integration form. We also derive the squeezed creation operator's eigenket and conclude that a † cosh λ + a sinh λ − 1 | 0 〉 is an excited squeezed state. [ABSTRACT FROM AUTHOR]

Abstract: The split-step Fourier method is used to study the energy switching characteristics of fiber nonlinear directional couplers with the third-order dispersion. The effects of the third-order dispersion increases with the third-order dispersion coefficient and input power and result in pulse shift and energy decreases. Adding high-order nonlinear can partly overcomes these effects. [Copyright &y& Elsevier]

A novel series of Er3+ doped LiYbW 2 O 8 phosphors were synthesized by high-temperature solid-state process. Upon 980 nm NIR laser excitation, the up-conversion emission spectra show that the intense green emissions and weak red emissions can be proposed as the transitions of 2H 11/2 →4I 15/2 , 4S 3/2 →4I 15/2 , 4F 9/2(2) →4I 15/2 and 4F 9/2(1) →4I 15/2 of Er3+ ions, respectively. The optical temperature sensing properties were carefully investigated on the basis of fluorescence intensity ratio (FIR) technology about energy level transitions of 2H 11/2 →4I 15/2 and 4S 3/2 →4I 15/2 in the range from 300 K to 500 K. Moreover, the maximum values of relative sensitivity (S r) and absolute sensitivity (S a) are separately about 1.62% K−1 at 300 K and 0.64% K−1 at 500 K, which can prove that the sensitivity of LiYbW 2 O 8 :Er3+ is superior to the latest reported materials for temperature sensors. Results evidence that the Er3+ doped LiYbW 2 O 8 phosphors can be outstanding candidates for optical temperature sensors with high S r and S a. [ABSTRACT FROM AUTHOR]

Abstract: The beam quality factor M 2 of multimode fiber lasers using coiling technique is studied based on the fiber bend loss theory. M 2 is obtained through calculating bend loss and intensity change of different modes in a multimode fiber. The influence of bend-induced field deformation on M 2 is evaluated. Relationship of M 2 to coiling radius is studied for the multimode fiber lasers. It is shown that M 2 keeps almost unchanged in some range of the coiling radius. The performance of mode selection is compared between fibers with the same V-parameter but different NA values. Fibers with smaller NA value are shown to be more effective for mode selection and are more conducive to achieving good beam quality laser output. [Copyright &y& Elsevier]

Abstract A new attitude determination method based on skylight polarization sensors and magnetometers is proposed for microsatellites in the low earth orbits. First, a two-channel polarization sensor is developed to measure skylight polarization and obtain the solar direction information. Second, the measurement model of the polarization sensor and three-axis magnetometer are derived. Finally, with the satellite attitude equation as the state equation, an extended Kalman filter is developed to estimate the satellite attitude. Simulation results manifested the feasibility of using polarization sensors and magnetometers to determine the attitude information of low earth orbit microsatellite. [ABSTRACT FROM AUTHOR]

A robust constrained autopilot control is addressed for a generic missile subject to angle of attack constraint, actuator nonlinearities and matched and mismatched uncertainties by utilizing integral barrier Lyapunov functional (IBLF) technique and dynamic surface control (DSC). Comparing with the existing IBLF-based literatures, the exploited methodology not only ensures the state constraint satisfaction, but also tackles the actuator limitations which include magnitude, rate and width constraints by introducing an auxiliary compensation design. For the problem of matched and mismatched uncertainties, an extended state observer (ESO) is explicitly utilized. Rigorous proofs are derived to demonstrate that the constrained state remains in its compact set and the closed-loop system achieves uniform ultimately bounded stability. Finally, Simulation results are performed to verify the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

A series of CaLa 1- x LiTeO 6 : x Dy3+ phosphors were synthesized via a conventional solid-state reaction method, and the effects of different Dy3+ doping concentrations on the luminescence properties of the phosphors were studied. The excitation spectrum indicated that these synthesized phosphors had strong absorption bands in near-ultraviolet (n-UV) region in the range from 300 to 500 nm. There were two sharp emission peaks in the visible region, which were located at 483 nm, 574 nm, corresponding to transitions of 4F 9/2 →6H 15/2 (magnetic dipole transition) and 4F 9/2 →6H 13/2 (electric dipole transition), respectively. The phosphor CaLa 0.95 LiTeO 6 :0.05Dy3+ shows superior thermal stability. When the temperature rises to 425 K, the luminous intensity remains at 79% compared with the initial intensity of 300 K. These results demonstrate that the CaLa 1- x LiTeO 6 : x Dy3+ phosphors have great potential as a single-phase luminescence material for near-ultraviolet (n-UV) excitation. [ABSTRACT FROM AUTHOR]

A novel terminal guidance system with a pulse-width-pulse-frequency (PWPF) modulator based on variable dead zone is designed for exo-atmospheric kill vehicle (EKV). At first, a three dimensional (3D) missile-target engagement kinematics is established on the line-of-sight (LOS) coordinate system, the guidance law is compensated by estimated maneuvering acceleration of target from nonlinear disturbance observer (DO). Secondly, a 3D terminal sliding mode guidance law with gradually increasing robustness is proposed for EKV, and the finite time stability of closed system is strictly proven. A PWPF modulator with variable dead zone is proposed to resist the sensitivity of LOS angle with relative distance decreasing, and the stability of modulator is proven by describing function technique. Finally, the guidance performances are assessed through a numerical simulation, the proposed guidance law is better attack precision than traditional guidance law, and the PWPF modulator with variable dead zone is more reasonable in fuel allocation and smaller on miss distance than traditional PWPF modulator. [ABSTRACT FROM AUTHOR]

Abstract: A pulse master-oscillator fiber power amplifier system with china-made large-mode-area fiber and a (6+1)×1 multimode combiner is demonstrated. The system generates up to 4.8W of amplified radiation (100kHz) at a wavelength of 1064nm with a near-diffraction-limited beam quality (M 2=1.2), and the overall slope efficiency with respect to the launched pump power is 50%. Some basic characteristics of this system, including the pulse-amplification characteristics, the gain characteristics, as well as the emission spectrum characteristics are investigated in detail. [Copyright &y& Elsevier]

A novel of Dy3+ activated Ba 2 ScMO 6 (M = Nb, Ta) phosphors were successfully synthesized by a solid-state reaction. Their phase structures and luminescence properties were characterized by X-ray powder diffraction (XRD), photoluminescence excitation (PLE) and photoluminescence (PL) spectra, concentration quenching mechanism and luminescence lifetime. The samples exhibited two prominent emission peaks in the visible wavelength region located at 494 and 583 nm, which were corresponding to the 4F 9/2 →6H 15/2 transition and the 4F 9/2 →6H 13/2 transition of Dy3+, respectively. According to Dexter's theory, the concentration quenching mechanism occurred through electric dipole-dipole interaction, and the Commission International del'Eclairagethe (CIE) chromaticity coordinates of Dy3+-doped of Ba 2 ScMO 6 (M = Nb, Ta) phosphors were very close to "ideal white" (x = 0.333, y = 0.333). Therefore, the results indicate that Ba 2 Sc 1- x MO 6 : x Dy3+ (M = Nb, Ta) phosphors could be used as near-ultraviolet (n -UV) excited single component white luminescent materials. [ABSTRACT FROM AUTHOR]

The absorption characteristics of three types of trace gases (sulfur dioxide, nitrogen dioxide and nitric oxide) were simulated through line-by-line integral algorithm utilizing the HITRAN2012 database. The effect of temperature, pressure, and other interfering gases were analyzed in the mid-infrared band (2–5 μm) and suitable sets of wavelengths were proposed for the mid-infrared differential absorption lidar (MI-DIAL). The absorption spectrum of one typical trace gas was measured and it was found to be reasonably consistent with that of the simulated one. The lidar system simulated results showed that the selected sets of wavelength can be used in MI-DIAL to detect the polluted gases. [ABSTRACT FROM AUTHOR]

In this letter, the adaptive estimation problem of the neuron states is studied for delayed neural networks with Markovian jumping parameters. Through employing a new nonnegative function and the M -matrix method, some sufficient conditions are derived to ensure the almost sure asymptotical stability for the dynamics of estimator error. Several suitable parameters update laws are found by the adaptive feedback control technique. Finally, a simulation example is provided to illustrate the effectiveness of the proposed adaptive estimation method. [ABSTRACT FROM AUTHOR]

In the present study, the possibility of using Fourier transform near-infrared spectroscopy (FT-NIR) to measure the concentration of polyphenols in Yunnan tobacco was investigated. Selected samples representing a wide range of varieties and regions were analyzed by high performance liquid chromatography (HPLC) for the concentrations of polyphenols in tobacco. Results showed that positive correlations existed between NIR spectra and concentration of objective compound upon the established linear and nonlinear regression models. The optimal model was obtained by comparing different modeling processes. It was demonstrated that the PLS regression covering the range of 5450–4250 cm −1 could lead to a good linear relationship between spectra and polyphenols with the R 2 of 0.9170. Optimal model generated the RMSEP of 0.254, RSEP of 0.0554, and RPD of 3.47, revealing that the linear model was able to predict the content of polyphenols in tobacco. Support vector regression (SVR) preprocessed by SNV obtained the predictable results with the R 2 of 0.8461, RMSEP of 0.374, and RPD of 2.36, which was inferior to PLS modeling. [ABSTRACT FROM AUTHOR]

We have demonstrated that the gold nanorods (GNRs) can be used as effective saturable absorbers for passively Q-switched erbium-doped fiber laser (EDFL). Two types of GNRs were synthesized by a seed-mediated growth method. The longitudinal surface plasmon resonance wavelengths of the GNRs with different aspect ratios were around 1068 and 1442 nm, respectively. The GNRs were mixed with sodium carboxymethylcellulose (NaCMC) to form GNRs-NaCMC films with different absorption wavelengths. Using these GNRs-NaCMC films, 9.6-μs pulses with a repetition rate of ∼22.9 kHz and 10.4-μs pulses with a repetition rate of ∼22.4 kHz were obtained from the passively Q-switched EDFLs at a pump power of ∼120 mW, respectively. [ABSTRACT FROM AUTHOR]

In order to improve the coupling efficiency of solar fiber lasers, a new kind of transversely pumping geometry is proposed. A two-stage concentration system is designed to concentrate the sunlight into the Nd-doped fiber coiled in a ring chamber with high-reflective inner surfaces. The primary concentrator is an off-axis Fresnel lens with a radius of 600 mm, and the secondary concentrator is a compound parabolic optical waveguide. With this concentration configuration, the collection efficiency can be as high as 21.4%. 73.5 W solar power is absorbed by the fiber core according to ray-tracing simulation. Output characteristics of the solar fiber laser are further analyzed by calculating the rate equations. 2.6 W laser output is obtained and the slope efficiency reaches 3.7%. [ABSTRACT FROM AUTHOR]

A series of single-phase Sr 2 ScTaO 6 :Ln3+ (Ln3+ = Sm3+/Dy3+) phosphors were successfully prepared by the traditional high-temperature solid-state method, and the effects of different Ln3+ doping concentrations on the luminescence properties of the phosphors were studied. The structure and luminescence properties of the phosphors were characterized by powder X-ray diffraction (XRD), photoluminescence, fluorescence lifetime and thermal stability. Under the excitation of 405 nm, the Sr 2 ScTaO 6 :Sm3+ samples have three emission peaks, corresponding to the 4G 5/2 →6H J/2 (J = 5, 7, and 9) transitions of Sm3+. The Sr 2 ScTaO 6 :Dy3+ samples have two main emission peaks at 493 nm (4F 9/2 →6H 15/2) and 581 nm (4F 9/2 →6H 13/2) for 366 nm excitation. Due to the different energy transfer between different energy levels, the decay time of Sm3+ and Dy3+ ions are different. The phosphors show excellent thermal stability, and the emission intensity are 85 % and 80 % for Sm3+ and Dy3+ ions at 423 K, respectively. These results demonstrate that the Sr 2 ScTaO 6 :Ln3+ (Ln3+ = Sm3+/Dy3+) phosphors have great potential as a single-phase luminescence materials for near-ultraviolet (n -UV) excitation. [ABSTRACT FROM AUTHOR]

Single-phased Sr 3 NaY(PO 4) 3 F:Ce3+, Mn2+ phosphors were synthesized by solid-state reaction method. The X-ray powder diffraction (XRD), photoluminescence (PL) spectrum and energy transfer from Ce3+ to Mn2+ of the samples were investigated. The PL spectrum of Sr 3 NaY(PO 4) 3 F:Ce3+, Mn2+ show there is a wide hump in the range of 300 to 450 nm of Ce3+ ions and characteristic peak of Mn2+ ions. The emission intensity of Mn2+ increased and that of Ce3+ decreased with increasing Mn2+ concentration. The color-tunable of the Sr 3 NaY(PO 4) 3 F:Ce3+, Mn2+ phosphors adjust from blue to yellow by changing the Mn2+ doping concentration. The decay curves show that energy transfer mechanism between Ce3+ and Mn2+ is quadrupole-quadrupole interaction. Moreover, the Sr 3 NaY(PO 4) 3 F:Ce3+, Mn2+ phosphors exhibit excellent thermal stability. Based on obtained results, the Sr 3 NaY(PO 4) 3 F:Ce3+, Mn2+ phosphors can act as efficient candidate phosphors materials for NUV-pumped white light-emitting diodes. [ABSTRACT FROM AUTHOR]