Key Technologies of Turbofan Engine for High Altitude Long Endurance Fly-wing UAV

High altitude long endurance(HALE) UAV has made great development since its birth and participation in war. With the expansion of combat mission to high-risk confrontation battlefield, HALE fly-wing UAV has become a hot-spot in the world today. In this paper, the requirements of HALE fly-wing UAV for turbofan engine are described, effect of key design parameters on the performance of turban engine is analyzed based on the basic principle of aero engine, the key problems and research progress of HALE fly-wing UAV are summarized. This paper is of important reference value in the selection of turbofan engine for HALE fly-wing UAV and the improvement of its adaptability design

Study on Matching Constant Speed Propeller for Piston Engine on MALE UAV

The medium altitude long endurance (MALE) UAV has many advantages, which can be used to carry out a variety of military and civil missions, and has become the research and development hotspot of various countries. In order to make the MALE UAV have good dynamic and economic performance in all flight stages, a method of matching constant speed propeller for piston engine is proposed. According to the speed and fuel consumption characteristic curve of piston engine, the economic working points of the engine are selected and then efficiencies of each propeller on the economic working points above are compared and analyzed. Wind tunnel tests of full scale engine and propeller are conducted. Results show that the proposed method could be used to select optimal constant propeller for preliminarily selected piston engine

Relationship Between Gene Duplicability and Diversifiability in the Topology of Biochemical Networks

Background: Selective gene duplicability, the extensive expansion of a small number of gene families, is universal. Quantitatively, the number of genes (P(K)) with K duplicates in a genome decreases precipitously as K increases, and often follows a power law (P(k)∝k-α). Functional diversification, either neo- or sub-functionalization, is a major evolution route for duplicate genes. Results: Using three lines of genomic datasets, we studied the relationship between gene duplicability and diversifiability in the topology of biochemical networks. First, we explored scenario where two pathways in the biochemical networks antagonize each other. Synthetic knockout of respective genes for the two pathways rescues the phenotypic defects of each individual knockout. We identified duplicate gene pairs with sufficient divergences that represent this antagonism relationship in the yeast S. cerevisiae. Such pairs overwhelmingly belong to large gene families, thus tend to have high duplicability. Second, we used distances between proteins of duplicate genes in the protein interaction network as a metric of their diversification. The higher a gene’s duplicate count, the further the proteins of this gene and its duplicates drift away from one another in the networks, which is especially true for genetically antagonizing duplicate genes. Third, we computed a sequence-homology-based clustering coefficient to quantify sequence diversifiability among duplicate genes – the lower the coefficient, the more the sequences have diverged. Duplicate count (K) of a gene is negatively correlated to the clustering coefficient of its duplicates, suggesting that gene duplicability is related to the extent of sequence divergence within the duplicate gene family. Conclusion: Thus, a positive correlation exists between gene diversifiability and duplicability in the context of biochemical networks - an improvement of our understanding of gene duplicability

Human Mitochondrial SUV3 and Polynucleotide Phosphorylase Form a 330-kDa Heteropentamer to Cooperatively Degrade Double-stranded RNA with a 3′-to-5′ Directionality*

Efficient turnover of unnecessary and misfolded RNAs is critical for maintaining the integrity and function of the mitochondria. The mitochondrial RNA degradosome of budding yeast (mtEXO) has been recently studied and characterized; yet no RNA degradation machinery has been identified in the mammalian mitochondria. In this communication, we demonstrated that purified human SUV3 (suppressor of Var1 3) dimer and polynucleotide phosphorylase (PNPase) trimer form a 330-kDa heteropentamer that is capable of efficiently degrading double-stranded RNA (dsRNA) substrates in the presence of ATP, a task the individual components cannot perform separately. The configuration of this complex is similar to that of the core complex of the E. coli RNA degradosome lacking RNase E but very different from that of the yeast mtEXO. The hSUV3-hPNPase complex prefers substrates containing a 3′ overhang and degrades the RNA in a 3′-to-5′ directionality. Deleting a short stretch of amino acids (positions 510–514) compromises the ability of hSUV3 to form a stable complex with hPNPase to degrade dsRNA substrates but does not affect its helicase activity. Furthermore, two additional hSUV3 mutants with abolished helicase activity because of disrupted ATPase or RNA binding activities were able to bind hPNPase. However, the resulting complexes failed to degrade dsRNA, suggesting that an intact helicase activity is essential for the complex to serve as an effective RNA degradosome. Taken together, these results strongly suggest that the complex of hSUV3-hPNPase is an integral entity for efficient degradation of structured RNA and may be the long sought RNA-degrading complex in the mammalian mitochondria