In this paper, we consider the problem of detecting a multichannel signal in interference and noise when signal mismatch happens. We first propose two selective detectors, since their strong selectivity is preferred in some situations. However, these two detectors would not be suitable candidates if a robust detector is needed. To overcome this shortcoming, we then devise a tunable detector, which is parametrized by a non-negative scaling factor, referred to as the tunable parameter. By adjusting the tunable parameter, the proposed detector can smoothly change its capability in rejecting or robustly detecting a mismatch signal. Moreover, one selective detector and the tunable detector with an appropriate tunable parameter can provide nearly the same detection performance as existing detectors in the absence of signal mismatch. We obtain analytical expressions for the probabilities of detection (PDs) and probabilities of false alarm (PFAs) of the three proposed detectors, which are verified by Monte Carlo simulations.

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In this paper, a MgO-SiO 2 -Al 2 O 3 -ZnO ceramic-glass coating sprayed on carbon steel was studied at high temperature. The property of the MgO-SiO 2 -Al 2 O 3 -ZnO ceramic-glass coating was analyzed in a range of 900°C and 1 150°C a share. The experimental results indicated that the MgO-SiO 2 -Al 2 O 3 -ZnO coating exhibited powerful anti-oxidation property for carbon steel. The MgO-SiO 2 -Al 2 O 3 -ZnO coating could improve the anti-oxidation performance of carbon steel by 84% at 1 050°C for 60 min. The Ea of blank and coated samples were 108.65 and 202.55 kJ/mol, respectively. The k p of the blank sample (0.61 mg 2 ·cm − 4 ·s − 1 ) was 7.6 times as much as that of coated sample (0.08 mg 2 ·cm − 4 · s − 1 ). It demonstrated the coating slowed down oxidation reaction rate and then improved the anti-oxidation performance of carbon steel. The possible protection mechanisms of the MgO-SiO 2 -Al 2 O 3 -ZnO ceramic-glass coating were also investigated using the SEM-EDS, XRD and TG-DTA characterization methods. The mixture formed between the coating and steel substrate (such as MgFe (x = 0.4, 0.85, 0.94)) played a role in blocking the spread of ions and improved the oxidation resistance of carbon steel during heating treatment. The synergy of the formed Al, Mg and Zn compound layers in the coating could also block spread of oxygen and iron ions and exert an influence on enhancing anti-oxidation property.

A novel micro-electromechanical systems inertial switch based on non-silicon surface micromachining technology has been designed, fabricated and characterized in the present work. Compared with the traditional inertial switch, a compliant cantilever beam as a stationary electrode has been proposed to prolong the contact time, which can realize sufficient elastic deformation during the contact between the electrodes. The dynamic contact process is analyzed theoretically and the corresponding mechanical impact mechanism is also explained. To investigate the contact-enhancing mechanism of the cantilever beam, the switch applied half-sine acceleration with various amplitudes in the sensitive direction is simulated with ANSYS software. The dynamic simulation results confirm the contact-enhancing mechanism described by the theoretical analysis and it is shown that the contact time (i.e., the switch-on time) can be prolonged effectively by utilizing the elastic deformation of the cantilever beam and increased with the applied accelerations. The inertial switch is successfully fabricated by electroplating and sacrificial layer processes technologies. The prototype has been characterized by dropping hammer experiment. The test results indicate that the contact effect is improved significantly and the contact time is ∼80 µs under the 297 g acceleration, and the maximum value is ∼410 µs for the 672 g acceleration amplitude, which is in general accordance with the simulated results. The mechanical contact between the cantilever beam and the proof mass is evaluated following thousands of impacts. The scanning electron micrographs of the contact surfaces indicate that the all-metal switch still keeps a good mechanical property after suffering the hot contact, and the contact resistance is also stable.

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