Cyclic cosmology from Lagrange-multiplier modified gravity

We investigate cyclic and singularity-free evolutions in a universe governed by Lagrange-multiplier modified gravity, either in scalar-field cosmology, as well as in $f(R)$ one. In the scalar case, cyclicity can be induced by a suitably reconstructed simple potential, and the matter content of the universe can be successfully incorporated. In the case of $f(R)$-gravity, cyclicity can be induced by a suitable reconstructed second function $f_2(R)$ of a very simple form, however the matter evolution cannot be analytically handled. Furthermore, we study the evolution of cosmological perturbations for the two scenarios. For the scalar case the system possesses no wavelike modes due to a dust-like sound speed, while for the $f(R)$ case there exist an oscillation mode of perturbations which indicates a dynamical degree of freedom. Both scenarios allow for stable parameter spaces of cosmological perturbations through the bouncing point.Comment: 8 pages, 3 figures, references added, accepted for publicatio

Analysis of Ensiling Suitability of Moringa, a Woody Plant

To effectively use the woody plant resources as animal feed, the ensiling suitability of Moringa including the dynamics of microbial community, chemical composition, and silage fermentation were studied. Tender stems and leaves of Moringa at the full-bloom stage of second cutting was used for silage preparation in Guizhou, China. After 3, 7, 15, 30, and 60 days of ensiling, five silos for each treatment were opened to analyze the fermentation characteristics. Moringa before ensiling contained 104 lactic acid bacteria (LAB), 106 aerobic bacteria, 104 coliform bacteria, 102 yeast, and 104 mold based on colony-forming unit/g of fresh matter (FM). The aerobic bacteria were dominant microbial population in the fresh Moringa. After 3 days of ensiling, the LAB increased as the highest numbers to dominate the silage fermentation. After 7 days of ensiling, the coliform bacteria and mold counts in Moringa silage dropped below the detection levels. The dry matter (DM) of fresh Moringa was 26.57%, their neutral detergent fiber (NDF) and crude protein (CP) contents were 27.40% and 20.90% on a DM basis, respectively. During ensiling, all silages did not emerge great difference in chemical composition. After 7 days of ensiling, all silages displayed a good fermentation patterns, with a low pH value. The result suggested that Moringa can be prepare as silage to be potential woody feed resources for livestock

A Wideband Multilayer Substrate Integrated Waveguide Cavity-Backed Slot Antenna Array

© 2017 IEEE. In this paper, a wideband 2 × 2 multilayer substrate integrated waveguide (SIW)-based cavity-backed slot array is proposed. The array element is constructed by stacking five layers of SIW cavity-backed slots and has a wide impedance bandwidth from 18 to 30 GHz. Two different feed networks based on probe coupling and slot coupling are introduced to maintain the wideband characteristic of the proposed element when employed in an array. Two 2 × 2 arrays fed by the proposed feed networks are designed, fabricated, and tested. The measured results show that both the arrays employing probe coupling and slot coupling feed networks have a wide impedance bandwidth over 30%. Within the obtained operation bands, good radiation performance is achieved. Moreover, advantages and disadvantages of the proposed two feed networks are discussed