231 research outputs found
Using regional geochemical survey data to trace anomalous samples through geochemical genes: The Tieshanlong tungsten deposit area (Southeastern China) case study
No full textIn order to determine and trace geochemical anomalies in soils, a tungsten (W) metallogene was constructed according to the idea of the gold (Au) metallogene previously developed. Based on the outcomes obtained for the Tieshanlong tungsten deposit area in southeast China from both three weathered profiles and a subset of data extracted from a regional geochemical survey database, a value of 40% of similarity between a W metallogene and an ideal ore was set as a criterion to individuate samples with potential W mineralization. Based on their W or Au metallogenes, a value of 70% of similarity was also chosen as the threshold criterion to locate samples with similar genes relative to a parent rocks or its weathered products. Based on the regional geochemical survey data available for the Tieshanlong tungsten deposit area, single elemental anomalies were determined and classified by means of the “seven levels' classification” method. Integrated anomalies were also determined and classified by using similarities (relative to their ideal ore) on W and Au metallogenes. Results indicate that the determined anomaly regions are well spatially consistent with the known deposits and that the metallogenes can be used to trace mineralized soil samples. Furthermore, the location of mineralized samples sourced by (altered) magmatic rock could be well pinpointed on geochemical genes, as well.
It was also observed that a value of 80% similarity for a lithogene (a geochemical gene based on a sequence of eleven immobile elements) which, similarly to metallogene, allow to compares samples to a specific parent rock and its weathered products, may be too stringent in the case of sedimentary rocks (even if metamorphosed) due to their relevant geochemical heterogeneity
Enhancing Membrane Distillation Performance Using Carbon Nanomaterials
No full textEMBARGO NOTE: This item is embargoed until 2027-12-01Membrane distillation (MD) is a promising technology to treat high salinity wastewater, but the high operational cost, lack of comprehensive understanding in its heat and mass transfer, and limited ability in treating various wastewater (e.g., low surface tension wastewater, volatile contaminants rich wastewater, etc.) have impeded its translation from bench scale to field scale. Nanophotonic-Enabled Solar Membrane Distillation (NESMD) utilizes free sunlight to produce localized heat on the membrane surface, which can make MD economically viable. However, the current membranes for NESMD exhibit either an increased mass transfer resistance to water vapor or a decreased photothermal properties after immobilized on the substrate membrane surface. Plus, unlike conventional MD whose performance dependency on the operational and environmental conditions are well understood, the operational and environmental effects on NESMD have not been fully understood. In addition, none of the existing NESMD membrane is anti-wetting, which limits its application only in dealing high surface tension wastewaters. Lastly, all current MD and NESMD membranes suffer from the problem of poor rejection against volatile contaminants (VC).
In this dissertation, core-shell structure hydrophilic photothermal nanofiber is used to solve the tradeoff between membrane permeability and solar absorptivity. With good water stability, high solar absorbance, fast heating and heat dissipation abilities, and no additional vapor mass transfer resistance, it can be used as a coating material to convert a commercial membrane to a photothermal active membrane. Compared to existing solar MD coating materials, the novel core-shell structure coating shows a better solar MD performance.
To understand the impact of operation and environmental factors on NESMD, the response of NESMD to the environmental (i.e., solar irradiance, and feed water temperature and salinity) and operating conditions (e.g., feed flowrate) were systematically investigated. The results show that NESMD perform better under higher solar irradiance and feed/permeate inlet temperature, and lower IR portion light source, feed salinity, and feed flowrate.
To enable NESMD in treating low surface tension wastewater, a dual functional, omniphobic−photothermal nanocomposite membrane was developed to achieve wetting resistance and low energy consumption. The membrane was prepared by forming a hierarchical structure of 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS17) modified carbon black (CB) nanoparticles (NPs) on a polyvinylidene fluoride (PVDF) membrane surface. The fluorinated CB NPs absorbed sun light to provide localized heating for NESMD, which increased membrane flux by 25% upon simulated solar irradiation at one sun unit. The utilization efficiency of solar energy in the NESMD process, 75.9%, is more than one order of magnitude higher than the energy efficiency of the conventional direct contact membrane distillation process. Furthermore, the re-entrant structure formed by the CB NPs together with the hydrophobic FAS17 coating led to low surface energy and hence omniphobicity, increasing the contact angle of the 80 vol% ethanol-in-water from 0 to 94.2°. As a result, the dual functional membrane exhibited much higher resistance to wetting by surfactants. Whereas the pristine PVDF membrane was wetted by 0.2 mM SDS, SDS had no effect on the dual function membrane over the whole SDS concentration range tested (0.1 – 0.4 mM). The photothermal activity, improved thermal efficiency, and strong wetting resistance make the dual functional omniphobic−photothermal membrane an excellent membrane material for the NESMD process.
Lastly, to improve the VC rejection ability in MD, Graphene oxide (GO) based membranes were fabricated by sandwiching GO and ethylene diamine crosslinked GO (GO-EDA) between a commercial polyvinylidene difluoride (PVDF) membrane and electrospun PVDF nanofiber, and tested their volatile contaminant rejection under different feed temperature, feed pH, and durations by using NH3 as a model volatile contaminant. For the first time, a volatile-contaminants-rejective MD membrane was reported, and the rejection mechanism of NH3 by GO membrane was revealed. Compared to commercial MD membrane, under different experimental conditions, our GO-based membranes always show two orders of magnitude better NH3 rejection with only one third drop in water vapor mass transfer resistance. The NH3 rejection of GO membrane is as high as 97.8%, which is 2.7 times better than the state of art RO membrane. The high volatile contaminants rejection makes our GO membrane good candidates in treating volatile contaminants rich wastewater
Three Essays in Advanced Graph Neural Networks: From Multivariate Temporal Forecasting to Heterophilous Graph Learning
No full textIn recent decades, the rapid advancement of computing power and data collection techniques has led to an unprecedented surge in structured and semi-structured data, necessitating the development of deep learning techniques to extract meaningful insights. While traditional deep learning methods have demonstrated remarkable power across various domains, they struggle to model the complex inter-relational structures inherent in real-world data, such as graphs. Graph Neural Networks (GNNs) have emerged as a powerful framework to address this limitation, enabling the effective representation of interdependent entities and achieving success in numerous real-world applications.
However, several challenges remain for GNNs, particularly in areas such as multivariate time series forecasting and heterophilous graph learning. For instance, while GNNs have been widely applied to multivariate time series forecasting, their potential in probabilistic forecasting remains under-explored. Most existing GNN-based forecasting models focus on deterministic predictions, failing to quantify predictive uncertainty, which is crucial for decision-making. Developing a GNN-based framework that effectively integrates probabilistic modelling into temporal forecasting remains an open challenge.
Additionally, GNNs are often incorporated into time series models to capture inter-series dependencies, while intra-series temporal dependencies are typically modelled separately using temporal models. However, in real-world systems, intra- and inter-temporal dependencies are inherently intertwined, making it challenging to fully exploit complex entangled relationships using existing methods. This raises the question of whether time series data can be transformed into a pure graph representation to unify these dependencies under a pure graph paradigm..
A Study on the Measurement of Relative Poverty in Developing Countries with Large Populations
No full textUnder the goal of global poverty eradication, it has become a forward-looking research aim to establish relative poverty criteria and identify people experiencing relative poverty in countries with different demographic characteristics. This paper introduces a new method to measure the relative poverty standard, which is to use the fuzzy decision tree algorithm to objectively estimate the relative poverty standard. The advantage of this algorithm lies in (1) it not only maintaining the regression idea of measuring absolute poverty, but also emphasizing the nonlinearity when the demand is increasing, which can reflect the change in human needs. (2) It overcomes the division of the traditional method which clearly distinguishes between those experiencing poverty and those who are not by means of a subjective threshold, and it also avoids the subjectivity of the selection of multidimensional indicators. (3) It overcomes the problems of data skewness and extreme value issues that traditional methods have, and can exhibit multi-dimensional characteristics. (4) Most importantly, this method can overcome the gap problem caused by the complex population structure in developing countries with huge populations, and is more adaptable under big data conditions than traditional methods. Taking China as an example, using data from the China Household Finance Survey for validation, the validation results show that the relative poverty standard in China in 2019 can be approximately delineated as 5288.5 RMB; this result is higher than the absolute poverty standard line delineated in China in that year, lower than the relative poverty standard line measured using the proportion method, and it can satisfy the average per capita food, tobacco, and alcohol consumption expenditure of Chinese residents in that year. Thus, compared with other methods, the fuzzy decision tree algorithm can better match the identification of relative poverty in developing countries with large populations
A nordehydroabietyl amide-containing chiral diene for rhodium-catalysed asymmetric arylation to nitroolefins
No full textA highly enantioselective rhodium catalysed asymmetric arylation (RCAA) of nitroolefins with arylboronic acids is presented using a newly developed, C-1-symmetric, non-covalent interacted, phellandrene derived, nordehydroabietyl amide-containing chiral diene under mild conditions. Stereoelectronic effects were studied, suggesting an activation of the bound substrate through the secondary amide as a hydrogen-bond donor.NSFC [21462004]; State Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources [CMEMR2014-A04]; GXNU; [2015GXNSFBA 139032]SCI(E)[email protected]
Design of a centrifugal linear vibrating feeder driven by an eccentric motor
No full textIn this paper, a novel linear vibrating feeder is designed that uses the centrifugal motion of an eccentric motor as the driving source. Firstly, the working principle of the linear vibrating feeder is theoretically analyzed and the dynamic model is established. Subsequently, a dynamic simulation of the system is carried out using the ANSYS software. The relationship between the displacement amplitude, vibration speed, and frequency of the linear vibrating feeder prototype is tested using a three-dimensional vibrometer, with an OT-10A copper terminal used to test the prototype. The experimental results indicate that, at a vibration frequency of 125 Hz, maximum vibration speeds of 1.23 mm/s and 1.70 mm/s are reached in the X- and Z-directions, respectively. The corresponding maximum amplitudes are 0.7 mm and 0.99 mm, and the material feeding speed reaches a maximum value of 123 mm/s. Compared with similar piezoelectric and electromagnetic vibrating feeders, the total weight of the prototype is reduced by a third, the noise is reduced by more than 20 dB, and the driving voltage is only 3.6 V. Hence, the performance of the linear vibrating feeder has been successfully demonstrated.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author
Application of Dehydroabietic Acid in Palladium-Catalysed Enyne Cycloisomerisation
No full textDehydroabietic acid (DAA) promotes palladium(0)-catalysed cyclisations of arene-tethered 1,7-enynols and 1, m-enynoates (m = 6,7) to give fused carbocyclic dienes. 6,6,6,5-Tetracyclic lactones are accessible by one-pot cycloisomerisation/DielsAlder reaction/lactonisation from 1,7-enynols. Furthermore, asymmetric counteranion-directed cataly-sis has been developed, which afforded an indene derivative with an all-carbon quaternary stereogenic center.SCI(E)ARTICLE142442-244735
Synthesis of a Co–Mo sulfide catalyst with a hollow structure for highly efficient hydrodesulfurization of dibenzothiophene
No full textCo–Mo sulfides with tube-like structures exhibit super high activity for HDS of DBT.</p
Structural Design of Household OLED Modular Combination Lamp
No full textWith the improvement of people’s life quality, the design of household lamps is not only limited to its function and practicability, but also has a higher exploration and pursuit in the expression of “home” culture in the shape of lamps. However modern lamps and lanterns is designed seldom according to the consistent that installs a style to come to put forward integral illume plan, it is difficult to satisfy human nature greatly, individuation, bedroom style diversity, and with a unity of modularity requirements. In this paper, the new lighting technology of OLED is studied in depth. Then, the method of modular design is applied to carry out innovative design of OLED household lighting fixtures, and a concrete design example is given. It not only enriches the design style of lamps and lanterns, but also pays attention to the independent demand of users’ emotion
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