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The current runway width design in China was still according to the aircraft size and the accumulated experience in the flight process, and there is no clear calculation method. This paper proposed a new runway width design method based on the wheel traces distribution of the aircraft. A laser test system was developed to measure the aircraft wheel tracks of 17 cross sections along the runway at a feeder airport. The test results indicated that when aircraft takes off or lands, the transverse wheels traces obeyed a normal distribution. The variation curve in landing was selected to fit a numerical formula, which was used to calculate the maximum landing variation within the forward motion range, and the expression of the wheel trace transverse distribution on the section with the maximum discretization was determined. At last, a failure probability of 0.0001% was chosen as the criterion to determine the runway width. It was showed that B737-30 should have at least 45 m width to ensure the 0.0001 % failure probability.

Aiming at the problems of high system complexity and low radiation efficiency of traditional multi-beam antenna array, the hybrid algorithm consisting of particle swarm optimization and convex optimization is proposed to synthesize the multi-beam pattern of the time modulated antenna array. Using this hybrid algorithm to optimize the timing of the radio frequency switch of antenna array, the multi-beam in the desired direction is realized, the array structure is simplified, and the radiation performance of the multi-beam pattern is improved. Through simulations, the hybrid algorithm effectively reduces the peak sidelobe level of main band and increases the peak radiation intensity of the low order sidebands. The experimental results further verify the correctness and efficiency of the theoretical analysis.

Developing correct, scalable, and fault-tolerant distributed databases is hard and labor-intensive. The increasing complexity of such systems under modern cloud infrastructures, e.g., geo-replicated multi-partitioned datacenters, further limits the number of design alternatives that can be explored in practice. There is therefore a need for the formal analysis of both their qualitative properties, e.g., data consistency, and their quantitative properties, e.g., latency, at an early design stage. In this paper we use formal modeling and both standard and statistical model checking techniques to explore the design space of replicated RAMP (Read Atomic Multi-Partition) transactions for geo-replicated databases. Specifically, we develop in Maude formal, executable specifications of three replicated RAMP designs, two by the RAMP developers and one by us, and analyze their data consistency properties. We further transform the Maude models into probabilistic rewrite theories for statistical model checking w.r.t. performance properties. Our results: (i) are consistent with the conjectures made by the RAMP developers; (ii) uncover our promising new design that not only provides all crucial data consistency guarantees but also outperforms the other design alternatives.

This paper is concerned with the global adaptive stabilization via output feedback for a class of uncertain planar nonlinear systems in the presence of uncertainty in both state and output equations. The systems under consideration are assumed to be dominated by a bounding system which is linear growth in the unmeasurable states but can be a polynomial output-dependent growth with unknown growth rate. Motivated by the closely related works, we propose a non-identifier based output feedback control scheme by using the idea of universal control integrated with a linear high-gain observer, whose gains are composed of two components, and both of them are dynamically updated in the new forms. The designed controller can globally regulate the states of the original system while maintaining global boundedness of the closed-loop system.

High-power single-longitudinal-mode regrowth-free gain-coupled distributed feedback laser diode based on ridge waveguide with periodic current injection is achieved at 990 nm. Our device is fabricated only by standard i-line lithography with micron-scale precision, obtains an excellent performance at high injection current. A continuous-wave power of over 0.681 W is achieved at 3 A. The maximum continuous-wave power at single-longitudinal-mode operation is up to 0.303 W at 1.4 A. Narrow linewidth emission has been reached with a 3 dB spectrum width less than 1.41 pm. The high side mode suppression ratio is over 35 dB. The lateral far field divergence angle is only 15.05°, the beam quality factor M2 is 1.245, achieving a laterally near-diffraction-limit emission. It is more beneficial for single-mode fiber coupling as pumping sources and other applications which require high beam quality at high power with easy fabrication technique.

With the increase of operating frequency of electronic devices, electromagnetic interference (EMI) radiation in the 20 GHz and higher frequency is becoming an increasingly difficult problem to solve, especially in the integrated circuit (IC) package with heat sink where the radiation from the chip will leak out through the gap between the heat sink and the ground plane of PCB. In this paper, the electromagnetic radiation mechanism of the package with heat sink in the frequency range up to 40 GHz is proposed from plenty of full-wave simulations using different absorbing materials, which is beneficial to the selection of package structural parameters and the suppression of radiation. According to the proposed mechanism, the methods to improve the EMI radiation suppression effect in the frequency range from 20 GHz to 30 GHz are designed.

As the helical gear is widely used as transmission part in the planetary gear train system, a six-degree-of-freedom bending-torsion-axis coupling dynamic model is established for the helical gear. In order to analyze the influence of the tooth profile modification on the gear meshing transmission, the tooth profile modification model is established, and the modification curve equation is analyzed by different curves. The results are substituted into the dynamic model of the original helical gear transmission, and a five-degree-of-freedom dynamic equation systematically considering tooth profile modification is obtained. The numerical simulation results show that the external stimulation, the tooth side gap and other factors have great influence on the vibration of the gear transmission, and the reasonable tooth profile curve can effectively reduce the system amplitude.

To solve the problem of tolerance design of the satellite antenna manipulator, a DH method was used to build the error scope model which included the equivalent analysis models of special tolerance, such as circular runout, coaxiality and parallelism. Based on this model, the error scope, maximal error range, position and attitude error of the manipulator end in each direction were calculated, and the results could be a reference for tolerance design of manipulators. The simulation results of a three-joint manipulator showed that the method was feasible, and the parallelism of the fitting surface of the root rotation joint which was close to the manipulator root and perpendicular to the arm axis affected the position and attitude accuracy of the manipulator end significantly. This study focused on the optimization and analysis of the tolerance, which could be a reference for the accuracy design and accurate assembling of satellite antennas.

A three-finger style grab mechanism is designed for space robot capturing a replaceable module on orbit in this paper. The grab mechanism is simplified by mathematical method and the grasping process is analyzed, then the collision detection model is built. The collisions between fingers and the matcher’s V-shaped grooves, between fingers and the matcher bottom surface, between the matcher bottom surface and the manipulator end-platform are analyzed in detail. The dynamic model of space floating base with six degree of freedom manipulator is established. The collision impact on the space robot is diminished by the application of the joint active damping control. The cases that the matcher has axial position error, radial position error, axial attitude error and radial attitude error at initial time are simulated. The results indicate that the three-finger style grab mechanism can complete the module grasp, the position and attitude error can be eliminated effectively.

A chalcogenide (ChG) vertical slot waveguide and a ChG horizontal slot waveguide racetrack resonator were proposed for gas sensing. The vertical slot waveguide and the upper strip waveguide of the horizontal slot waveguide are suspended to enhance light-gas interaction. The waveguide sensors were optimized and the sensing performances were studied numerically.

There is an emerging trend of integrating machine learning (ML) techniques into database systems (DB). Considering that almost all the ML toolkits assume that the input of ML algorithms is a single table even though many real-world datasets are stored as multiple tables due to normalization in DB. Thus, data scientists have to perform joins before learning a ML model. This strategy is called learning after joins, which incurs redundancy avoided by normalization. In the area of ML, the Support Vector Machine (SVM) is one of the most standard classification tools. In this paper, we focus on the factorized SVM with gaussian kernels over normalized data. We present factorized learning approaches for two main SVM optimization methods, i.e., Gradient Descent (GD) and Sequential Minimal Optimization (SMO), by factorizing gaussian kernel function computation. Furthermore, we transform the normalized data into matrices, and boost the efficiency of SVM learning via linear algebra operations. Extensive experiments with nine real normalized data sets demonstrate the efficiency and scalability of our proposed approaches.

A two-segment regrowth-free gain-coupled distributed feedback (DFB) laser monolithically integrated different gain contrast segments was proposed, realizing both wavelength-tunable (5 nm) and wavelength stabilization characteristics, controlled by a single electrode only. At current larger than 320 mA, side mode suppression ratio reached >30 dB with 3 dB linewidth

A low-cost regrowth-free narrow-strip single-longitudinal-mode diode laser, based on periodic anodes defined only by i-line lithography is proposed. With the periodic anodes separated by surface insulated grooves acting as a 44th-order gain grating, a high gain contrast is achieved without introducing effective index coupling. The CW output power of the device without facet coatings is up to 100.9 mW/facet at 980.63 nm in single-longitudinal-mode operation with a single facet having a power conversion efficiency of up to 18.6% and a slope efficiency of 0.53 W/A. The highest side-mode suppression ratio is 45 dB with a linewidth below 889 MHz, at 350 mA. The beam parameter product, M2, in the slow axis is 1.85, achieving a near diffraction-limited beam quality. A novel method for easy surface gratings fabrication is first presented, wherein, 4-μm-width periodic surface grooves, acting as waveguide ridges, are defined once by i-line lithography only without regrowth, nanoscale gratings fabrication, or facet coating. Owing to the low-cost fabrication methods and good performances, our single-longitudinal-mode devices can be used for widespread practical applications.

In order to perform target recognition under realistic conditions, it is necessary to extract local invariant features of a real scene. This paper proposes a novel local invariant feature extraction method for high dynamic range images. Firstly, based on the multi-exposure fusion HDR image calculation model, this paper introduces the perceptual model of human eye vision for scene irradiance, and establishes a complete theoretical model of HDR imaging and mapping. Then, this paper proposes a new LIFT extraction method, which performs LIFT detection on the scene reflection layer and LIFT description on the scene illumination layer. Finally, experiments have shown that this method can increase the number of correct matching of feature points of machine vision wide baseline images. The research results in this paper combine the invariant feature matching technology with the HDR image technology that can record the irradiance value of the real scene, thus expanding the application background of the image LIFT extraction technology.

GaN as the third generation semiconductor material has good prospects for development. The wide bandgap of GaN enables it to work at high temperature, and has higher breakdown voltage and better breakdown characteristics. The structure of AlGaN/GaN based high electron mobility transistor (AlGaN/GaN HEMT) is simulated and analyzed by using simulation software Silvaco ATLAS. Firstly, the effect of field plate structure on breakdown voltage is introduced, and then the effect of field plate length on breakdown voltage of devices is analyzed. The results show that the change of field plate length has great influence on breakdown voltage, and the optimal value is determined by testing, which has practical guiding significance for the actual device fabrication.