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On 13th November 2016, the Kaikoura region of New Zealand was struck by a major Mw7.8 earthquake. In this study, coseismic deformation field is derived from 1 Hz high-rate GPS observations based on the GAMIT track solution module, combining with PCA spatial filtering method firstly. Then the 5 s peak displacement of P-wave (Pd) and the peak ground displacement (PGD) are extracted from the real-time simulated kinematic displacements of the trackRTr module. Finally, the warning magnitude is calculated from the statistical regression model. Our results indicate that the duration time of the kinematic deformation is up to 2 min. The KAIK and HANM stations, which are closest to the epicenter, have secondary severe deformation. And the deformation amplitude of the north stations of the epicenter is larger than that of the south. The static coseismic deformation field from high-rate GPS observations shows the characteristics of the focal mechanism of strike-slip after thrust. In addition, the Pd warning magnitudes from different stations have a significant difference, with the maximum magnitude difference of Mw2.5. Considering the timeliness and reliability of the warning magnitude jointly, the warning magnitude from the four-station PGD joint warning method of reasonable spatial distribution can reach its initial stability (Mw7.56) at 23 s after the event, while final stability (Mw7.78) at 110 s, which is consistent with the USGS moment tensor magnitude (Mw7.8).

For large lifting body plane symmetric aircrafts, lateral maneuvering near the target may cause severe aerodynamic coupling between the lateral channels, possibly resulting in instability of the rolling channel. Aiming at this kind of coupling problem, the lateral system is decomposed based on the singular perturbation theory, and the cascade model of the inner and the outer loops is established. The outer loop is used as an example to design the sliding mode (SM) control law, and the stability of the closed-loop system is analyzed. The sliding mode disturbance observer (SMDO) is also employed to estimate and compensate for the coupling term and improves the robustness of the rolling channel against the lateral coupling. Simulation results show that the designed controller has good dynamic characteristics and anti-disturbance ability, improving the robustness and performance of the control system.

This letter presents a planar triple-band multiple- input-multiple-output (MIMO) antenna that meets GSM900/1800 and LTE2600 bands protocols. The antenna element contains three individual meander-line-type inverted-L radiators; the highest frequency band radiator is fed by a transmission line, while the other two utilize the proximity-coupling feeding mechanism driven by the highest band radiator. The MIMO antenna is incorporated with two symmetric triple-band antenna elements and two physical decoupling devices. The two antenna elements are closely spaced with 1/15 wavelength of the lowest band. The two decoupling devices, a T-shaped slot and a meandering microstrip-line resonator, are built for the highest and the lowest frequency bands, respectively. Meanwhile, a negligible mutual coupling effect in middle band is achieved by using a collinear-placed transverse meander-line pair in the MIMO antenna. The antenna prototype measurement results show good impedance matching with low mutual coupling effect. The calculated envelope correlation coefficient verifies the suitability of the proposed antenna for mobile wireless access applications.

Precision guided weapon is the main weapon in modern warfare. The precision guided weapon with photoelectric guidance has the advantages of strong resolution and high accuracy. It is widely used in the fields of sea-to-sea, air defense, anti-missile, space attack and defense. As optoelectronic guided weapons play an increasingly prominent role in modern warfare, their corresponding countermeasures are also constantly developing, which makes the combat environment more complex and requires them to continuously enhance adaptability to the increasingly complex battlefield environment. Based on the summary of the application of existing optical detection technologies such as infrared, visible light and laser semi-active in guided weapons, the shortcomings of the current technology in complex combat environments are analyzed, such as harsh natural weather, complex background and human interference. In view of the current development of multi-spectral detection, polarization imaging, laser three-dimensional imaging, quantum detection and other new technologies, the current research progress and results are introduced. It mainly includes multi-spectral multi-segment segmentation against true and false target camouflage recognition, polarization imaging against rain and fog, bad natural weather, laser three-dimensional imaging in the application of anti-complex background and penetration shielding and other research advantages and research progress. Finally, the problems in the application of the new detection technology and the key technologies that need to be broken through are systematically analyzed, and it is suggested that the guidance application of the new detection technology should be promoted through the joint attack of the basic technology and the application technology.

There exists a steady-state error in the closed-loop system output with some conventional linear active rejection control approaches when the pitch channel control variable of the near space vehicle is the angle of attack. In this study, a cascaded linear active disturbance rejection control approach based on the cascaded control idea is proposed. Both the inner-loop controller and the outer-loop controller are designed by the linear active disturbance rejection control method. The inner-loop is built by angular rate feedback to improve dynamic performance of the closed-loop system, and the outer-loop is built by angle of attack feedback to remove the undesired steady-state error. The approach is employed to a hypersonic near space vehicle autopilot. The numerical simulations show that the proposed approach preserves the performances on time domain and frequency domain as good as those of the conventional active disturbance rejection control approaches, and it has the better performances on disturbance rejection and angle of attack command tracking accuracy than those of some previous active disturbance rejection control approaches.

The angular rate is the derivative of pitch angle other than the derivative of angle of attack, there determinately exists a steady-state error in the closed-loop system output with the linear active rejection control in the case that the control variable is the angle of attack. In this study, an unbiased linear active disturbance rejection control approach based on two-loop control is proposed. The internal-loop is built by angular rate feedback to improve the damping, and the external-loop is built by angle of attack feedback to realize the system output accurately reproducing the reference input. Furthermore, a linear active disturbance rej ection control is applied for the external-loop controller design. The approach is employed to a hypersonic near space vehicle autopilot. The numerical simulations show that the proposed approach preserves the performance on frequency domain as good as that of the conventional active disturbance rejection control approach, the steady-state error of the closed-loop system is well removed, and the angle of attack command is tracked with better accuracy than that of some previous active disturbance rejection control approaches.

This paper presents a compact dual-band MIMO antenna that is compatible to the IEEE 802.11n wireless LAN standards. The MIMO antenna contains two tree-type elements placed back to back with distance of one-sixth wavelength of 2.4GHz; the element in the MIMO antenna is structured with a two-branch tree-type planar inverted-L monopoles, the lengths in both branches are set to the electrical quarter-wavelength of the frequency bands of 5.2GHz and 2.4GHz respectively. The MIMO antenna characterized by small size, low mutual coupling effect and nearly omni-directional coverage in radiation pattern make it entirely applicable to the mobile wireless network applications. The measurement results of the fabricated MIMO antenna demonstrate the success of the suggested design topologies.

Few investigation interests have been focused on anti-windup design under Active Disturbance Rejection Control scheme. In this study, an anti-windup compensation strategy under ADRC scheme is proposed. The strategy is also a special case of the unified framework for anti-windup compensation. By feeding the actual plant input into the extended state observer, the extended state is correctly estimated while actuator saturation emerges, then the adequate controller output is accordingly produced to alleviate the adverse influence of actuator saturation on closed-loop dynamics. The approach is applied to a hypersonic near space vehicle pitch-axis autopilot design with fin-deflection saturation, the capability and effectiveness of the proposed approach is demonstrated by the results.

The angular rate is the derivative of pitch angle other than the derivative of angle of attack, there determinately exists a steady-state error in the closed-loop system output in the case that the control variable is the angle of attack. In this study, A linear compensation term is introduced into the extended state observer, and an unbiased linear active disturbance rejection control approach is proposed. The approach is employed to a hypersonic near space vehicle autopilot. The numeral simulations show that the proposed approach preserves the performance on frequency domain as good as that of the conventional active disturbance rejection control approach, furthermore, the steady-error of the closed system is removed simultaneously, and the angle of attack command is tracked with better accuracy than that of some previous active disturbance rejection control approaches.