In many cases non-cooperative things that have no available ID numbers need to be identified via electromagnetic sensing. In order to obtain target's accuracy Radar Cross Section (RCS) character, separating target signal from background is a necessary step in RCS measurement of heavy targets mounted on a metal pylon and both geometric fit and algebraic fit can be applied in the separation procedure. In this paper, the feasibility of Kasa method in separation of target signal and background signal is researched. The bias of Kasa method under whole circle circumstance is deducted, and the validation of simulation data using Kasa method has been accomplished. The separation result of two measurement data is compared between Kasa method and ODR (Orthogonal Distance Regression) method, and the comparison result shows that Kasa method can be used in separation of background and target signal.

The infrared detection has been widely used in electrical industry with the safety, high sensitivity, high efficiency and calculability. Referring to technical regulations such as Application rules of infrared diagnosis for live electrical equipment (DLIT 664-2008 ), only infrared image feature and temperature difference can be indicated for the heating equipment caused by voltage. The quantitative analysis of internal defects parameters such as capacitance and dielectric loss with infrared images hasn't been developed. In order to guide the precise infrared detective and diagnose for the electical equipments in substation, this paper built the equivalent physical and theoretical heating models for several types of the equipments such as arresters and current transformers to research the identification principles of the internal defects with infrared thermography. According to the heating principles of electrical equipments, the equivalent physical models were fabricated to simulate the internal defects with the same heat-transferring path and surface. By setting the calculated heating power, degradation of the key parameters such as dielectric loss, capacitance, resistive current of arresters was simulated and estimated with infrared detection of the surface. 3-D models of the electric equipments were built for precise calculation of the internal heat-transferring process and external surface temperature distribution. The calculation was based on the design sketches of the equipments in the finite-element method. Models was configured with special heat source, the characteristics parameters of the materials and other unknown parameters probed with iterative algorithm. The results were proved by the infrared detection of the real equipments and the equivalent physical models. It's concluded that temperature rise and difference of the surface can be used to judge the internal defects of the electrical equipments in substation. A variety of heating simulation models for electrical equipments can be built with the method in this paper. It's expected that the more detailed detection and diagnosis principle with infrared thermography will be set down.

Abstract:In order to reveal the function of Mg on the characteristics of mechanical properties in high strength low alloy steel, the steels containing with different Mg contents were refined with vacuum induction furnace and rolled with double-stick reversible rolling mill. The characteristics of mechanical properties and rolled microstructure were systematically investigated in present study. The results show that, the yield and the tensile strengths increase with Mg content from 0.0008% to 0.0026%. The 0.0026%Mg addition makes the yield strength, tensile strength, and elongation of steel increase to 473MPa, 605MPa and 36.5%, increasing by 38MPa,70MPa, and 8% compared with the steel without Mg addition. The improved toughness is obtained both the transversal and longitudinal impact, and the increment in the Charpy impact toughness is also characterized to increase with the concentrations from 0.0008% to 0.0026%. The improved toughness and tensile of Mg-containing steels are attributed to both the refined microstructure and the bainite dominated microstructure in steel. Moreover, the bainitic structure obtained by the addition of Mg into the molten steel results in a continuous yield behavior emerges in 0.0026%Mg steel.

Tear propagation is a typical breakage modality of fabric laminates. In this paper, analysis methods and their empirical formulas about tear propagation of a kind of fabric laminate which is used in high altitude lighter-than-air vehicle (LTA) is studied. The methods include Griffith’s energy balance method, Thiele’s empirical formula method, Stress field consideration method and critical stress intensity factor method. Testing about tear propagation strength in biaxial stress is done by a tailor-made testing machine to study on the methods. And then a comparison is drawn between these formulas and results of the experimentation. Subsequently, advantages and disadvantages of these formulas and their scope of application are concluded. While by using the empirical formulas, the analysis of tear propagation of different incision shapes is given. It is useful for the further study on different fabric laminates.

Original defects in the envelope material easily torn damage under overpressure, when the stratospheric airship in use. This paper based on linear elastic theory studied the tear strength of envelope material containing initial center crack and proposed theoretical model for this problem. Choose Vectran fiber as a reinforcing layer of stratospheric airship envelope material, Combined with digital speckle method measuring tear strength of envelope materials containing different initial center crack length. Comparative analysis found that the theoretical model applicable to estimate the tear strength of envelope material, that center initial crack width ratio is less than 50%.It estimation error within 5% .It satisfies the requirement of engineering application accuracy.