ORGANIC TEA HAS MORE HEALTH BENEFIT AND ENVIRONMENTAL ADAPTABLITY THAN CONVENTIONAL TEA

Organic tea is booming in China since it is regarded as a high quality and healthy product. To confirm this believing, six pairs of organic and conventional teas from six farms in Zhejiang and Fujian Provinces, eastern China have been analyzed. The results show that organic teas had significantly higher tea polyphenols and water extracts compared to the conventional ones in most cases. Catechins, especially the epigallocatechin gallate, epicatechin gallate and epigallocatechin were significantly higher in organic tea. The concentrations of proline andγ-aminobutyric acid were also significantly higher in organic tea. However, the amino acids, particular theanine, aspartic acid and arginine were generally lower due to insufficient supply of mineral N in soils under organic management. These results could conclude that organic tea is more health benefit and environmental adaptable compared to its conventional counterpart

Research and application of maximum surface subsidence model under the condition of repeated mining in weakly cemented strata

The characteristics of surface subsidence under the condition of repeated mining in weakly cemented strata are of great significance to the safe and efficient mining and ecological restoration of coal resources in weakly cemented mining areas in western China. Theoretical analysis, similar simulation, numerical simulation and field monitoring are used to study the migration law of overlying strata and surface subsidence model under repeated mining conditions in weakly cemented strata, and the model is applied in engineering. The bulking characteristics of weakly cemented rock and the influence mechanism of repeated mining overburden strata movement on surface subsidence are discussed through theoretical analysis. The ‘maximum surface subsidence model under the condition of repeated mining in weakly cemented strata’ is established. There is a linear relationship between the bulking coefficient of weakly cemented rock, the mining thickness of lower coal and the maximum surface subsidence of weakly cemented strata. Through similar simulation and numerical simulation, the characteristics of repeated mining overburden and surface subsidence in weakly cemented strata are analyzed. The research results show that the development law of the separation height of the initial mining and repeated mining of the weakly cemented strata is basically the same, and both show a step-like rise. The surface subsidence curve of repeated mining is asymmetrically distributed, and the maximum subsidence value is biased towards the side of open cut. The maximum development height of overlying strata, the maximum surface subsidence value and the surface subsidence coefficient after initial mining and repeated mining are given. The established maximum surface subsidence model is used to predict the maximum surface subsidence value on site. The predicted value of the maximum surface subsidence model is similar to the measured value on site during the mining process of the working face, which verifies the rationality of the ' maximum surface subsidence model under the condition of repeated mining of weakly cemented strata '. At the same time, the predicted value of the maximum surface subsidence after the mining of the working face can provide a reference for the actual work on site

Influence of a groove-structured vortex generator on the drag reduction characteristics of a multiphase pump

The oil–gas mixture pump significantly contributes to marginal oil field extraction and remote transportation of deep-sea oil. Nevertheless, during the operation of the mixture pump, it is inevitable to encounter problems like the separation of the mixed media from the hydraulic components as well as the gas phase from the liquid phase, which leads to enhancing the flow resistance of the mixed media. Therefore, this study investigates the influence of a groove-structure vortex generator on the drag reduction characteristics of a helical axial-flow gas–liquid multiphase pump under the design flow rate condition and various inlet gas content rates. The findings show that the vortex generator with diverse groove depths can prevent the separation of the mixed media from the blade suction surface effectively and minimize the flow resistance of the media in the 1/10 of the blade inlet. In particular, excellent drag reduction results were gained with a maximum drag reduction rate of 36.7% when the relative depth was 3/40. In addition, the efficiency of the mixture pump increased by a maximum of 2.1%, and the head increased by a maximum of 4.3%. The significance of this study lies in its potential to further optimize the design and performance of gas–liquid multiphase pumps. It provides new insights into the design and application of vortex generators. It offers robust support for the optimization and enhancement of gas–liquid multiphase pumps

Validating automated eye disease screening AI algorithm in community and in-hospital scenarios

Purpose:To assess the accuracy and robustness of the AI algorithm for detecting referable diabetic retinopathy (RDR), referable macular diseases (RMD), and glaucoma suspect (GCS) from fundus images in community and in-hospital screening scenarios.MethodsWe collected two color fundus image datasets, namely, PUMCH (556 images, 166 subjects, and four camera models) and NSDE (534 images, 134 subjects, and two camera models). The AI algorithm generates the screening report after taking fundus images. The images were labeled as RDR, RMD, GCS, or none of the three by 3 licensed ophthalmologists. The resulting labels were treated as “ground truth” and then were used to compare against the AI screening reports to validate the sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) of the AI algorithm.ResultsOn the PUMCH dataset, regarding the prediction of RDR, the AI algorithm achieved overall results of 0.950 ± 0.058, 0.963 ± 0.024, and 0.954 ± 0.049 on sensitivity, specificity, and AUC, respectively. For RMD, the overall results are 0.919 ± 0.073, 0.929 ± 0.039, and 0.974 ± 0.009. For GCS, the overall results are 0.950 ± 0.059, 0.946 ± 0.016, and 0.976 ± 0.025.ConclusionThe AI algorithm can work robustly with various fundus camera models and achieve high accuracies for detecting RDR, RMD, and GCS

A constant gradient sound ray tracing underwater positioning algorithm considering incident beam angle

The spatial and temporal variation of sound velocity in sea water can make sound waves refract along the propagation direction, and effective elimination of refraction artifacts is very important to improve the accuracy of underwater acoustic positioning. When the sound velocity profile is known, sound ray tracing is an effective method to reduce the refraction artifacts. The existing sound ray tracing methods require that the incident beam angle is known, while the underwater acoustic positioning systems based on the distance intersection principle usually do not directly measure the incident beam angle. A constant gradient sound ray tracing underwater positioning algorithm considering incident beam angle is proposed, which can trace sound ray and estimate target position respectively by iterative calculation, and the incident beam angle is determined by a search method. In order to improve the calculation efficiency, a transcendental equation solution method is proposed to determine the incident beam angle iteratively. The experimental results show that the proposed method effectively eliminate the effect of the refraction artifacts by using sound velocity profile, and the calculation efficiency of the transcendental equation solution method is better than the search method

Chemically Tuned Waterflooding in Carbonate Reservoirs: Experimental and Simulation Investigation

Low salinity waterflooding (LSWF) has been widely investigated to reduce the residual oil saturation in swept areas and thus improve oil recovery. Recently, extensive studies on crude oil, brine, and rock system reported that LSWF and increased sulfate ion concentration in the injected water could change rock wettability during waterflooding. The objective of this paper is to provide a deeper understanding the effect of sulfate ion concentration and low salinity waterflooding on oil recovery improvement due to wettability modification by applying experimental and simulation approaches. An experimental model with the properties of the same core was designed to understand the effect of LSWF and sulfate ion concentration on improved oil recovery during the waterflooding process. Reactive transport simulator (CrunchFlow 2007) was used to simulate the experimental result. Once the experimental and simulation results were matched, a sensitivity analysis was done by changing sulfate ion concentration and calculate the wettability index based on chromatographic separation of tracer (SCN-) and sulfate ion (SO42-) to investigate how could affect the sulfate ion concentration on modifying rock wettability. So when the area between SCN- and SO42- increased, the wettability modified toward water wet. The experimental results found that both LSWF and increased sulfate ion concentration three times can improve oil recovery factor by 10% and 19.5%, respectively. The reactive transport simulator results showed that the area between SCN-and SO42- increased as SO42- concentration increased and improved the core wettability toward more water wetness. The temperature has a significant effect on the SO42- adsorption and the high temperature resulted in more SO4 adsorption and the core wettability modified to be more water wetness. Combined two approaches, experimental and simulation, could be a viable technique to understand LSWF and sulfate ion concentration effect on improved rock wettability toward water-wet

Selective Water Shutoff Technology Study and Application of W/O Emulsions

A new emulsifier PN-1 was synthesized. The crude oil of Jinzhou oilfield could be well emulsified by PN-1. The activated crude oil forms water/oil emulsion below 80% water-cut. Coreflood experiments were conducted to demonstrate the selective placement of the activated crude oil. Water shutoff operations using this new technique were conducted in Liaohe oil field of CNPC, resulting in 167,000 ton of incremental oil a 295,000 cu m of reduced water. The activated viscous crude was a selective water plugging agent, and could be successfully bullheaded into the formation without damaging non-target oil zones