Lightweight Design of Solar UAV Wing Structures Based on Sandwich Equivalent Theory

In this paper, an equivalent method based on sandwich plate is deduced, and the equivalent parameters of the honeycomb plate are obtained. With these equivalent parameters, the honeycomb plate equivalent FEM simulation model and actual model are established, and three-point bending simulations of the equivalent model and the actual model three-point are completed. Then, a three-point bending test of a real honeycomb sandwich panel was performed for comparison with the simulation result, which agrees well with the test result and shows the effectiveness of the equivalent model. The equivalent model of honeycomb sandwich plate win ribs is established for structural topology optimization and wing static simulation analysis, and a prototype of the solar UAV is made for flight testing according to the topology optimization results. The simulation and prototype test results indicated that the sandwich equivalent theory is suitable for the lightweight design of solar UAV wing structures with honeycomb sandwich plate materials, and this method can provide a reference for the same type of wing structure design.

The extension of thixotropy of cement paste under vibration: a shear-vibration equivalent theory

The rheology of cement paste under vibration follows the transformation from Bingham model to Hershel-Bulkly model to Power-Law model. Most of the existing research is obtained through a large number of experiments in the data fitting process, and cannot express the time-varying characteristics of viscosity. Furthermore, thixotropy of cement paste is based on static experiment and cannot be applied under vibration. In this paper a shear-vibration equivalent theory is proposed, which consider the effect of vibration is the same as the shear effect on the viscosity change of cement paste. Combining vibrational shear equivalent theory and HI theory, the rheological changes of cement paste under vibration are obtained through numerical simulation. This theory has been verified by a series of experiments with numerical simulations, and can be used to study the rheology of concrete under vibration.

Perceptual design method research in product design

On the purpose of deepening method research of perceptual analysis, based on the description of the relationship between perceptual design and rational design, the importance of perceptual design in modern product design is clarified. To strengthen the emotional expression of the product, the study focuses on sort perceptual design method with the background of perceptual design internalization and equivalent theory. Taking the perceptual design as the bond, how the method located sensibility in product design is analyzed. By taking advantage of formal beauty rule, more perceptual elements are added into product design to summarize the method and principle based on the product perceptual design.

Modeling of a Plasma Antenna with Inhomogeneous Distribution of Electron Density

The distribution of the electron density along a plasma antenna can influence the antenna’s performance. But little has been done in this regard in former studies. In this paper, a model of a practical plasma antenna with an inhomogeneous distribution of electron density is founded according to the transmission-line equivalent theory of a metal monopole, from which the current distribution and the radiation pattern of a plasma antenna with appropriate parameters are calculated. The results show that the electrical current distribution, the maximum radiation direction, and the beamwidth of a plasma antenna vary with electron density distributions. To validate the model, the plasma antenna with the same parameters is also simulated based on electromagnetic software HFSS. It is found that the results from the two ways are almost consistent.

The Axiomatic Structure of Empirical Content

We define the empirical content of an economic theory as the least restrictive observationally equivalent theory. We show that the empirical content of a theory is captured by a certain kind of axiomatization, with axioms that are universal negations of conjunctions of atomic formulae. (JEL B41, D01, D11)