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We have developed, manufactured, and tested a new feed design for interferometric radio telescopes with "large-N, small-D" designs. Such arrays require low-cost and low-complexity feeds for mass production on reasonable timescales and budgets, and also require those feeds to be compact to minimize obstruction of the dishes, along with having ultra-wide frequency bands of operation for most current and future science goals. The feed presented in this paper modifies the exponentially tapered slot antenna (Vivaldi) and quad-ridged flared horn antenna designs by having an oversized backshort, a novel method of maintaining a small size that is well-suited for deeper dishes (f ∕ D ≤ 0. 2 5). It is made of laser cut aluminum and printed circuit boards, such that it is inexpensive (≲ 7 5 USD per feed in large-scale production) and quick to build; it has a 5:1 frequency ratio, and its size is approximately a third of its longest operating wavelength. We present the science and engineering constraints that went into design decisions, the development and optimization process, and the simulated performance. A version of this feed design was optimized and fabricated for the Canadian Hydrogen Observatory and Radio-transient Detector (CHORD) prototypes. When simulated on CHORD's very deep dishes (f ∕ D = 0. 2 1) and with CHORD's custom first-stage amplifiers, the on-sky system temperature T sys of the complete receiving system from dish to digitizer remains below 30 K over most of the 0.3–1.5 GHz band, and maintains an aperture efficiency η A between 0.4 and 0.6. The entire receiving chain operates at ambient temperature. The feed is designed to slightly under-illuminate the CHORD dishes, in order to minimize coupling between array elements and spillover. [ABSTRACT FROM AUTHOR]

Black soldier fly larvae contains nutrients such as crude protein, amino acid, fat and trace elements, which can partially or even completely replace soybean meal and fish meal in animal feeding. It is the most economical and safe measure to solve protein shortage in animal feed industry. In order to meet the demand of insect protein feed, the industrial culture of black soldier fly has become a big trend. Different breeding substrates and breeding environment are the limiting factors of black soldier fly in large-scale breeding. In this paper, the characteristics of intestinal flora of black soldier fly and its influencing factors on the level of industrial culture are discussed, which provides ideas and reference for further improving the efficiency of industrial breeding of black soldier fly. [ABSTRACT FROM AUTHOR]

Straw is both a by-product of agriculture and a valuable resource for biomass. Turning straw wastes into resource will increase industrial efficiency, promote the cycle of planting and breeding, and meet the needs of people's livelihood such as clean heating in villages and towns. In China, the zoning layout of straw utilization is still not perfect, resulting in structural excess of straw in different regions and in certain season. The problems of straw resource waste and environmental pollution are outstanding. Based on the theory of comprehensive utilization of straw, we proposed a comprehensive utilization path of straw, which was “agricultural priority, agricultural production, rural energy utilization, and diversified utilization of fertilizers, feed, fuel, base materials and raw materials”. The goal was “market user demand orientation, continuous supply of raw materials, comprehensive utilization for agriculture and industry, and significant improvement in comprehensive benefits”. The comprehensive utilization potential of straw in China was 876 million tons, an increase was 156 million tons from 2015, Fertilizer utilization potential of straw was 476 million tons; Feed utilization potential of straw was 220 million tons; Energy utilization potential of straw was 120 million tons; Base material and raw material utilization potential of straw was 60 million. Among them, fertilizer, feed and energy utilization increased by 87.224 million tons, 51.232 million tons and 17.20 million tons from 2015. The straw resources in the six regions of Northeast China, North China, East China, South China, Northwest China and Southwest China could be fully utilized. The demand for forage in Central China was still unsatisfactory. Through fertilizer and feed utilization, the directly and indirectly substitution potential of chemical fertilizers was: nitrogen fertilizer (N) 14.816 million tons, phosphate fertilizer (P2O5) 4.19 million tons, potash fertilizer (K2O) 18.851 million tons, saving cost of fertilizers about 6 859 million yuan, equivalent to saving costs for unit straw replacement of fertilizer by 98.5 yuan per ton of straw. Through energy utilization, it could replace 59.824 million tons of fossil energy such as coal, reduce 150 million tons of carbon dioxide emissions, 4.487 million tons of sulfur dioxide, 2.243 million tons of nitrogen oxides, and 40.68 million tons of soot. The economic benefits of carbon emissions trading could reach 2 025 million yuan, equivalent to the increase in straw carbon emissions by16.9 yuan per unit ton of straw. Therefore, environmental and economic benefits were significant. The results of the study provide a reference for improving the comprehensive utilization level of straw, and the government decision-making and industrial development. [ABSTRACT FROM AUTHOR]