Rails worked under a harsh environment in the electromagnetic launching. Measurement of temperature at or close to the rail-and-armature interface of an electromagnetic launch (EML) is capability that would provide a significant insight into the EML performance. This interface is difficult to access and requires any sensor to tolerate sliding contacts, high electrical currents, and extreme temperatures. As a result, the existing temperature sensor technology has not been successful in providing data at that location. The development of the fiber Bragg grating (FBG) may provide a potential solution for this requirement. By designing and building a temperature measurement system based on FBG, we can collect dynamic temperature data of the rail during the launch. This paper establishes a model of transient thermal field of EML, calculates the variation of rail temperature under the effect of the Joule heat, and compares with the measurement result. After adding the model in the case of the protection package of FBG temperature sensor, the simulation data agrees well with the test data, and the sensors do not been destroyed even disturbed. All of the above prove that this method is feasible, and the sensors can be used in the following tests.

Ion generation based on face detection and recognitionXiaokang Wu^{1, a}, Chenggang Xie^{2, b}, Qin Lu^{2, c1}National University Of Defense Technology, Changsha 410073, China;^a172896292@qq.com,^bqingqingzijin_k@126.com,Keywords: face detection, face recognition, key frame, video abstraction In order to facilitate users browse the behaviors and expressions of interesting objects in a video quickly, need to remove the redundancy information and extract key frames related to the object interested. This paper uses a fast face detection based on skin color, and recognition technology using spectrum feature matching, decompose the coupling video, and classify frames related to the object into different sets, generate a different video abstraction of each object. Experimental results show that the algorithm under different light conditions has better practicability.

How to design an impact platform that can provide a strong electromagnetic environment for all kinds of precision electronic equipment and experimental reference for strong electromagnetic protection is of great significance. In this article, an electromagnetic coil system that generated a strong magnetic field environment was designed and studied. First, the coil parameters and coil structure were designed. Then, the Comsol finite element software was used to simulate and design the three-component coil. The coil distance and turns were adjusted to make the coil center produce a uniform magnetic field area and meet the strong magnetic field index. Finally, the coil system was built to verify the magnetic field generated by the coil through experiments. This system will be used to simulate the strong magnetic field environment that produces different high precision and may occur in the operating environment of the equipment. It will also be used to provide strong magnetic field impact test support conditions for aerospace, naval vessels, and various types of equipment, so as to find and solve the problem of antistrong magnetic reliability of equipment in the design stage.

Magnetic shape memory alloys with multiple entropy change (ΔS_M ) peaks are promising to extend the working temperature window (ΔT _eff) in active magnetic refrigeration. They usually have multi-step martensitic transformations, since the multiple variations of structure and magnetic states lead to the one-to-one corresponding ΔS_M peaks. In this work, we report an interesting Ni₄₂Co₈Mn_37.5In_12.5 magnetocaloric alloy, which exhibits only one-step martensitic transformation but generates two considerable ΔS_M peaks with the value of 7.2 J K⁻¹ kg⁻¹ and 9.9 J K⁻¹ kg⁻¹ under 6 T respectively. This phenomenon is attributed to the restriction internal stresses stemming from the lattice mismatch between martensite and austenite, the random local stresses produced by defects, the interfacial hindrances of wide phase boundaries, and the inhibition of dispersed precipitates, which divide the one-step transformation into two discrete stages. Such multiple ΔS_M peaks are beneficial for expanding the working temperature window of magnetocaloric refrigerators.