In this paper, the efficiency of the robust design methods for large array antennas with the simultaneous presence of interval amplitude, phase excitation errors and antenna position errors is addressed. The CPU time for a single iteration of the robust optimization method is greatly reduced by the proposed prior knowledge-based algorithm (PKA). Mathematically, the array factor bounds of array antennas with interval uncertainties can be taken as the bounds of the modulus of the sum of the complex intervals with both the modulus and argument errors (CIMAS). The PKA for the modulus of CIMAS consists of three theorems: (1) the necessary conditions for each complex interval for the upper modulus bound of CIMAS; (2) the method for judging whether the lower modulus bound of CIMAS equals zero; and (3) the necessary conditions for each complex interval for the nonzero lower modulus bound of CIMAS. The efficiency and accuracy of PKA are demonstrated by comparisons with two popular methods. Based on Genetic Algorithm (GA) and PKA, the robust designs of array antennas under multiple constraints are also presented.

Surface mount technology (SMT) plays an important role in integrated circuits, but due to thermal stress alternation caused by temperature cycling, it tends to have thermo-mechanical reliability problems. At the same time, considering the environmental and health problems of lead (Pb)-based solders, the electronics industry has turned to lead-free solders, such as ternary alloy Sn-3Ag-0.5Cu (SAC305). As lead-free solders exhibit visco-plastic mechanical properties significantly affected by temperature, their thermo-mechanical reliability has received considerable attention. In this study, the interface delamination of an SMT solder joint using a SAC305 alloy under temperature cycling has been analyzed by the nonlinear finite element method. The results indicate that the highest contact pressure at the four corners of the termination/solder horizontal interface means that delamination is most likely to occur, followed by the y-direction side region of the solder/land interface and the top arc region of the termination/solder vertical interface. It should be noted that in order to keep the shape of the solder joint in the finite element model consistent with the actual situation after the reflow process, a minimum energy-based morphology evolution method has been incorporated into the established finite element model. Eventually, an Improved Efficient Global Optimization (IEGO) method was used to optimize the geometry of the SMT solder joint in order to reduce the contact pressure at critical points and critical regions. The optimization result shows that the contact pressure at the critical points and at the critical regions decreases significantly, which also means that the probability of thermal-induced delamination decreases.

Structural deformation caused by environmental loads (solar irradiation, snow and ice, devices heat dissipation, etc.), could severely deteriorate the performance of high-frequency large-aperture active phased array antenna (HLAPAA). The existing sensor placement methods for monitoring the real-time status of HLAPAA have issues with slow convergence rate, limited global search ability, and low optimization accuracy, especially with large HLAPAA with tens thousands of degrees of freedom. In this paper, we propose a novel HLAPAA sensor placement method with an adaptive double population grey wolf optimizer (ADGWO). This method introduces adaptive sentinel wolves into the basic grey wolf optimizer (GWO), improves the population update strategy and thus improves the convergence rate plus the global search ability. First, based on four benchmark functions, the test performance of ADGWO and other popular intelligence algorithms is provided. The comparison shows that the proposed method has excellent convergence speed, higher solution quality, stronger global search ability, and better robustness, making it suitable for optimal sensor placement (OSP) of large structures. Then, the ADGWO is applied to the sensor placement of an X-band HLAPAA. Compared with other OSP methods, the proposed method has advantages in terms of sensor distribution and computational and hardware cost. Finally, verification is carried out using an experimental antenna platform equipped with the optimal fiber Bragg grating (FBG) strain sensor configuration. The measurement results show that the reconstructed shape is in good agreement with the real (deformed) shape, and the calculated radiation pattern matches the radiation pattern measured in the anechoic chamber. Therefore, the proposed method and monitoring system based on ADGWO has broad application prospects in condition monitoring of large, lightweight, flexible antenna structures working in harsh environments.

Radio astronomy is a discipline of dynamics and wonders. The vast universe has many secrets to unravel. As one of the important facilities in this discipline, radio telescopes play a key role in collecting astronomical data and unraveling mysteries. With the demand of radio astronomy for a higher frequency, wider bandwidth, higher gain, and higher pointing accuracy, the aperture of the radio telescope is gradually increasing, and its electrical performance and structure have become tightly coupled. Therefore, how to ensure the stable and efficient operation of the telescope for the long-term operation has become the urgent demand for large aperture high-performance radio telescopes. Therefore, this paper firstly makes a comparison of the overall condition of large radio telescopes in nearly a decade that are both constructed and operated, including the progress of radio telescopes that are being constructed and the planning for construction. Then, systematically summarized the latest research progress of electromechanical coupling technology from 3 aspects of connotation and application of electromechanical coupling, and performance guarantee under slowly varying load and performance guarantee under rapidly varying load from the perspectives of design, manufacturing, and observation operating. Lastly, the future research direction of electromechanical coupling technology is pointed out according to the development trend of radio astronomy.

In this paper, the possibility to improve target detection performance in passive bistatic radar by jointly exploiting multiple signals at different carrier frequencies emitted by the same illuminator is investigated, namely multi-frequency passive bistatic radar (MFPBR) coherent integration. Since the carrier frequency of each signal is agile, the MFPBR coherent integration suffers from the problems of range phase incoherence and Doppler broadening. In order to tackle these challenges, a multi-frequency coherent integration target detection algorithm for passive bistatic radar is proposed. Specifically, this scheme corrects the Doppler broadening effect via TSP. Then, low sidelobe filtering based on convex optimization is carried out to remove the range phase incoherence and obtain the MF of the target's energy. Meanwhile, the high-range-resolution profiles (HRRP) of target can be generated. The advantage of the proposed algorithm is that it can obtain superior coherent integration and detection performance for both the single and multiple targets scenarios compared to existing methods. Finally, a series of measured and simulation results are presented to demonstrate the effectiveness of the proposed algorithm.