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Three-dimensional mapping is an essential component of autonomous Micro Aerial Vehicle (MAV) navigation. The paper focuses on the 3D spatial representation method of MAV to overcome the collision problem caused by soft constraints, control error, and planning with the center of mass by inflating the occupancy grid map. A fast incremental inflated map construction method is proposed, which reduces the time-consumption caused by the increase of map range and inflated size. The method focuses on areas of the map that occupied state changes and introduces two arrays that record newly appearing and disappearing obstacles. Then, a series of breadth-first search algorithms are used to traverse the parts of the inflated map that need local modification to update the inflated map. Moreover, a sliding map model is designed based on the MAV position, which is suitable for large-range autonomous flight. The effectiveness of the proposed approach is verified with simulated and actual flight data. The proposed method takes about 3 ms to construct the inflated map with a local update range of 16 m × 16 m × 6 m. [ABSTRACT FROM AUTHOR]

The total quota control and reserve of rare earths are important means for the sustainable development and utilization of rare-earth resources. Focusing on the government reserve of rare-earth products under stochastic demand, this paper analyses the interactive decisions of the government and the rare-earth firms from a game-theoretic perspective. The government determines the total quantity, reserve quantity and reserve–release quantity of the rare-earth products to maximize social warfare, while the firm decides the price of rare-earth products to maximize its own profit. The results show that the production cost and the expected net present value (NPV) of the reserve are important factors affecting the government's decisions. When the expected NPV of the reserve is below a threshold, the government adopts the no-reserve strategy: it determines only a total quota index that maximizes the current-period social welfare but keeps no reserve. When the expected NPV of a reserve is higher than the above threshold but lower than the production cost, the government adopts the low-reserve strategy: it determines a total quota index and a low reserve that are both in increasing in the expected NPV of reserve, and will release the reserve as many as possible if there is a supply shortage. When the expected NPV of a reserve is higher than both the above threshold and the production cost, the government adopts the high-reserve strategy: it sets a total quota index which is sufficiently large to cover the entire market demand, reserves a large amount, and releases part of the reserve to completely fill the demand gap (if any). [ABSTRACT FROM AUTHOR]

In 2020, China put forward the goals of "peak carbon dioxide emissions" and "carbon neutrality" ("double-carbon") and it is urgent for the energy industry to achieve green transformation. Aiming at the rigid requirements of the carbon-peaking and carbon-neutrality goals ("double-carbon"), this study established a performance evaluation index system for an energy supply chain of a four-tier structure based on the "double-carbon" goals, calculating its weight by the analytic hierarchy process (AHP). On this basis, a three-stage data envelopment analysis (DEA) evaluation model was established to evaluate the performance of the energy supply chain in 2010–2019. According to the three-stage DEA evaluation mode, the initial input–output efficiency value of the energy supply chain was calculated by the DEA-BCC (extended by Banker, Charnes and Cooper) model and DEA-CCR (proposed by Charnes, Cooper and Rhodes) model and the influence of environmental noise was eliminated by stochastic frontier analysis (SFA) regression; we then obtained the adjusted efficiency value for the energy supply chain. At the same time, taking 2015 as the dividing point, the advantages and disadvantages between the traditional energy supply chain and new energy supply chain were analyzed and summarized. Further analysis and suggestions are provided to consumers, enterprises and countries from four aspects: energy supply, energy production and processing, energy transmission and distribution and energy consumption. [ABSTRACT FROM AUTHOR]

The genomic and carbohydrate metabolic features of Pseudoalteromonas agarivorans Hao 2018 (P. agarivorans Hao 2018) were investigated through pan-genomic and transcriptomic analyses, and key enzyme genes that may encode the process involved in its extracellular polysaccharide synthesis were screened. The pan-genome of the P. agarivorans strains consists of a core-genome containing 2331 genes, an accessory-genome containing 956 genes, and a unique-genome containing 1519 genes. Clusters of Orthologous Groups analyses showed that P. agarivorans harbors strain-specifically diverse metabolisms, probably representing high evolutionary genome changes. The Kyoto Encyclopedia of Genes and Genomes and reconstructed carbohydrate metabolic pathways displayed that P. agarivorans strains can utilize a variety of carbohydrates, such as d-glucose, d-fructose, and d-lactose. Analyses of differentially expressed genes showed that compared with the stationary phase (24 h), strain P. agarivorans Hao 2018 had upregulated expression of genes related to the synthesis of extracellular polysaccharides in the logarithmic growth phase (2 h), and that the expression of these genes affected extracellular polysaccharide transport, nucleotide sugar synthesis, and glycosyltransferase synthesis. This is the first investigation of the genomic and metabolic features of P. agarivorans through pan-genomic and transcriptomic analyses, and these intriguing discoveries provide the possibility to produce novel marine drug lead compounds with high biological activity. [ABSTRACT FROM AUTHOR]

Exopolysaccharides (EPSs) are carbohydrate polymers produced and secreted by microorganisms. In a changing marine environment, EPS secretion can reduce damage from external environmental disturbances to microorganisms. Meanwhile, EPSs have promising application prospects in the fields of food, cosmetics, and pharmaceuticals. Changes in external environmental pH have been shown to affect the synthesis of EPSs in microorganisms. In this study, we analyzed the effects of different initial fermentation pHs on the production, monosaccharide composition, and antioxidant activity of the EPSs of Pseudoalteromonas agarivorans Hao 2018. In addition, the transcriptome sequence of P. agarivorans Hao 2018 under different initial fermentation pH levels was determined. GO and KEGG analyses showed that the differentially expressed genes were concentrated in the two-component regulatory system and bacterial chemotaxis pathways. We further identified the expression of key genes involved in EPS synthesis during pH changes. In particular, the expression of genes encoding the glucose/galactose MFS transporter, phosphomannomutase, and mannose-1-phosphate guanylyltransferase was upregulated when the environmental pH increased, thus promoting EPS synthesis. This study not only contributes to elucidating the environmental adaptation mechanisms of P. agarivorans, but also provides important theoretical guidance for the directed development of new products using biologically active polysaccharides. [ABSTRACT FROM AUTHOR]

Given a set of sensors distributed on the plane and a set of Point of Interests (POIs) on a line segment, a primary task of the mobile wireless sensor network is to schedule covering the POIs by the sensors, such that each POI is monitored by at least one sensor. For balancing the energy consumption, we study the min-max line barrier target coverage (LBTC) problem which aims to minimize the maximum movement of the sensors from their original positions to their final positions at which the coverage is composed. We first proved that when the radius of the sensors are non-uniform integers, even 1-dimensional LBTC (1D-LBTC), a special case of LBTC in which the sensors are distributed on the line segment instead of the plane, is NP -hard. The hardness result is interesting, since the continuous version of LBTC to cover a given line segment instead of the POIs is known polynomial solvable. Then we present an exact algorithm for LBTC with uniform radius and sensors distributed on the plane, via solving the decision version of LBTC. We argue that our algorithm runs in time O (n 2 log n) and produces an optimal solution to LBTC. The time complexity compares favorably to the state-of-art runtime O (n 3 log n) of the continuous version which aims to cover a line barrier instead of the targets. Last but not the least, we carry out numerical experiments to evaluate the practical performance of the algorithms, which demonstrates a practical runtime gain comparing with an optimal algorithm based on integer linear programming. [ABSTRACT FROM AUTHOR]

Many marine bacteria secrete exopolysaccharides (EPSs), which are made up of a substantial component of the macro-molecules surrounding cells. Recently, the wide demand for EPSs for food, cosmetics, pharmaceutical and other applications has led to great interest in them. In this study, an EPS produced by marine bacteria Aerococcus uriaeequi HZ strains (EPS-A) was isolated and purified to examine its structure and biological function. The molecular weight of EPS-A analyzed by high-performance liquid gel filtration chromatography (HPGFC) is found to have a number average of 2.22 × 10⁵ and weight average of 2.84 × 10⁵, respectively. High-performance liquid chromatography (HPLC) and Fourier-transform⁻infrared (FT⁻IR) analysis indicate that EPS-A was a polysaccharide composed of glucose and a little mannose. In addition, the flocculating rate of sewage of EPS-A was 79.90%. The hygroscopicity studies showed that hygroscopicity of EPS-A was higher than chitosan but lower than that of sodium hyaluronate. The moisture retention of EPS-A showed similar retention activity to both chitosan and sodium hyaluronate. EPS-A also can scavenge free radicals including both OH• free radical and O₂• - free radical and the activity to O₂• - free radical is similar to vitamin C. Safety assessment on mice indicated that the EPS-A is safe for external use and oral administration. EPS-A has great potential for applications in medicine due to its characteristics mentioned above.