No abstract

The objective of this study was to test the effectiveness of mapping the canopies of Firmiana danxiaensis (FD), a rare and endangered plant species in China, from remotely sensed images acquired by a customized imaging system mounted on an unmanned aerial vehicle (UAV). The work was conducted in an experiment site (approximately 10 km 2 ) at the foot of Danxia Mountain in Guangdong Province, China. The study was conducted as an experimental task for a to-be-launched large-scale FD surveying on Danxia Mountain (about 200 km 2 in area) by remote sensing on UAV platforms. First, field-based spectra were collected through hand-held hyperspectral spectroradiometer and then analyzed to help design a classification schema which was capable of differentiating the targeted plant species in the study site. Second, remote-sensed images for the experiment site were acquired and calibrated through a variety of preprocessing steps. Orthoimages and a digital surface model (DSM) were generated as input data from the calibrated UAV images. The spectra and geometry features were used to segment the preprocessed UAV imagery into homogeneous patches. Lastly, a hierarchical classification, combined with a support vector machine (SVM), was proposed to identify FD canopies from the segmented patches. The effectiveness of the classification was evaluated by on-site GPS recordings. The result illustrated that the proposed hierarchical classification schema with a SVM classifier on the remote sensing imagery collected by the imaging system on UAV provided a promising method for mapping of the spatial distribution of the FD canopies, which serves as a replacement for field surveys in the attempt to realize a wide-scale plant survey by the local governments.

Since titanium alloys have been widely used as joint replacement biomaterials, their superficial lubrication has evolved to be a critical factor for normal use. For this purpose, one kind of typical microgel, poly­(NIPAAm-co-AA), was synthesized by emulsifier-free emulsion polymerization and used as an aqueous lubricating additive between titanium alloy contacts. The results show that the as-synthesized microgels reduced the coefficient of friction by 46% and the wear volume by 45%, compared with pure water. Meanwhile, due to their thermosensitive property, the microgels were employed as smart additives to modulate the interfacial friction, which was attributed to the transition of the hydrated state and the elastic deformation of microgel particles. To further dissect the lubrication mechanism, it was found that the lubricating property of microgels was substantially associated with the formation of a hydrated layer surrounding microgels, microbearing effect, interfacial adsorption, and the colloidal stability. Looking beyond, as one kind of soft colloidal lubricant, the microgels may play an important role in the biomedical metal lubrication.

The impact of trade policy on foreign trade is becoming increasingly prominent. This paper chooses the Chinese soybean futures market to study the impact of Sino-US trade friction. The results show that the asymmetric effect and volatility of the Chinese soybean futures market become larger after the beginning of Sino-US trade friction. In addition, the relationship among Chinese soybean futures, Chinese soybean meal futures, and Chinese soybean oil futures is strengthened. However, the relationship between Chinese soybean meal futures and American soybean meal futures and between Chinese soybean oil futures and American soybean oil futures has weakened since Sino-US trade friction started.

Addition of 10 vol% biomass-based methyl levulinate (ML), ethyl levulinate (EL), butyl levulinate (BL), gamma-valerolactone (GVL), dimethyl carbonate (DimC), and diethyl carbonate (DieC) in gasoline were selected as blended fuels. Physical-chemical properties of six different blends of biofuels and gasoline, including miscibility, octane number, distillation, vapor pressure, unwashed gum content, solvent washed gum content, copper corrosiveness, water content, mechanical admixtures, and lower heating value was evaluated according to the China National Standards. Blended fuels were then evaluated on the performance and emissions of a gasoline test engine without any modification. The results showed that all biomass-based fuels at 10 vol% have good miscibility in gasoline at temperatures of –30 to 30 °C. Experiments were performed at 4500 rpm engine speed at different engine loads (from 10% to 100% in 10% intervals). Results showed slightly lower engine power at different loads with the blended fuels than those from gasoline fuelled engine. However, the brake specific fuel consumption (BSFC) with the blended fuels was slightly higher than that from gasoline. Emission of carbon monoxide (CO), total unburned hydrocarbon (THC) and oxides of nitrogen (NOx) was reduced significantly from the blended fuels compared to gasoline while carbon dioxide (CO2) emission was slightly higher than that from gasoline. The data suggests that 10 vol% addition of biomass-based levulinates and carbonates fuels to gasoline is suitable for use in gasoline engines.