Spectra of Random Regular Hypergraphs

In this paper, we study the spectra of regular hypergraphs following the definitions from Feng and Li (1996). Our main result is an analog of Alon's conjecture for the spectral gap of the random regular hypergraphs. We then relate the second eigenvalues to both its expansion property and the mixing rate of the non-backtracking random walk on regular hypergraphs. We also prove the spectral gap for the non-backtracking operator of a random regular hypergraph introduced in Angelini et al. (2015). Finally, we obtain the convergence of the empirical spectral distribution (ESD) for random regular hypergraphs in different regimes. Under certain conditions, we can show a local law for the ESD.

Enhanced Negative Thermal Expansion Property Deduced by the Breaks of Superstructure

The HfV2O7/HfMo2O8 composite were prepared in situ. The phase, structure and thermal expansion property were analyzed. The results indicate the composite consist of cubic HfV2O7 and hexagonal HfMo2O8. The two types of structures were coexisted and mixed uniformly, and interacted with each other. The mutual nested structure suppressed the formation of 3×3×3 superstructure in HfV2O7 (RT) introduced by the reaction in situ. The promoted coupled rotation of quasi-rigid polyhedron units could enhance the negative thermal expansion (NTE) property. The HfV2O7/HfMo2O8 composite exhibits excellent NTE property from 250 to 673 K (at least) with CTE -3.09 × 10-6 K-1. The good NTE property and thermal stability over a wide temperature range, especially near the RT range, bring a good potential application in designing zero thermal expansion materials.

Analysis of the Influence of Shrinkage Tensile Stress in Potting Material on the Anti-Overload Performance of the Circuit Board

In this article, the influence of shrinkage tensile stress in potting materials on the anti-overload performance of a circuit board was studied. Firstly, the phenomenon of shrinkage tensile stress in common potting materials was analyzed, and it was found that the commonly used potting adhesives displayed large shrinkage characteristics. Secondly, a small experiment was set up to verify that the shrinkage tensile stress of potting adhesives would lead to printed circuit board (PCB) deformation, and the shrinkage stress was contrary to the acceleration direction of overload. Thirdly, the influence of potting adhesives on the overload resistance of the PCB was analyzed. However, the shrinkage tensile stress in the potting adhesive weakened the anti-overload ability of the circuit board. When there was a small amount of expansion stress in the potting adhesive, the overload resistance of the circuit board could be partially increased. From the analysis, it is indicated that a material with a certain expansion property, elasticity, and dense structure should be selected as the potting adhesive. This article provides a reference for improving the overload resistance of electronic devices.

VARIOUS FACTORS AFFECT THE QUALITY OF FERMENTED CASSAVA STARCH

Fermented cassava starch is one of modified cassava starch products and used in many countries in several food products. The fresh extracted cassava starch is modified by a process of fermentation and sun drying by means the traditional methods. Several works have shown that fermentative process alters the starch granule, giving fermented starch its characteristics are different from those of the native cassava starch. The main difference between fermented cassava starch[A1] and native cassava starch reside in the expansion property. Understanding the transformation of physico-chemical properties of cassava starch during fermentation is important for controlling the production processes. This discourse refers to the several works that intend to chemically show the expansion property of fermented cassava starch, considered a chemically and enzymatically modified product, with acidic characteristics, perforated granules and high expansion capacity. Expansion is a natural characteristic of fermented cassava starch, defined as the growth rate of the dough during oven cooking, also referred to as expansion rate. The main aim of this discourse is to get a better understanding how to manage the production processes in order to achieve greater consistency in the quality of sour cassava starch.Â