Two-Stage Optimal Dispatching of Wind Power-Photovoltaic-Solar Thermal Combined System Considering Economic Optimality and Fairness

Aiming at the problems of large-scale wind and solar grid connection,how to ensure the economy of system operation and how to realize fair scheduling between new energy power stations,a two-stage optimal dispatching model of wind power-photovoltaic-solar thermal combined system considering economic optimality and fairness is proposed.Firstly,the first stage dispatching model takes the overall economy optimization of the system as the goal and the principle of maximizing the consumption of wind and solar output,obtains the optimal output value under the economic conditions of each new energy station,and then obtains the maximum consumption space of the new energy station.Secondly,based on the optimization results of the first stage,the second stage dispatching model uses the dispatching method of fuzzy comprehensive ranking priority to prioritize the new energy stations,and then makes a fair allocation to the dispatching of the wind and solar stations.Finally,the analysis of a specific example shows that themodel can take into account the fairness of active power distribution of new energy stations on the basis of ensuring the economy of system operation,make full use of the consumption space,and realize the medium and long-term fairness distribution of dispatching plan.

Pre-reduction of WO_(3)-Co_(3)O_(4)by H_(2)-C_(2)H_4 in a fluidized bed

In order to avoid the formation ofηphase(W_(6)Co_(6)C or W_(3)Co_(3)C)that adversely affects the sintering process and its products in the preparation process of ultra-fine WC-Co powder,a technical route of prereduction of WO_(3)-Co_(3)O_(4)to WO_(2)-Co and then deep reduction carbonization to WC-Co powder has been proposed.This study mainly investigates the influence of gas partial pressure on the pre-reduction process of WO_(3)-Co_(3)O_(4)under a mixed atmosphere of H_(2)-C_(2)H_(4)-Ar at 600℃and establishes the kinetic equations of pre-reduction and carbon evolution.The results indicate that increasing the partial pressure of hydrogen is conducive to the rapid and complete conversion of WO_(3) to WO_(2).High carbon content can be generated by the deposition of C_(2)H_(4),and it hinders the diffusion of the reducing gas;WO_(3)still cannot be completely reduced to WO_(2)as the partial pressure of C_(2)H_(4) increases to 60%.For the carbon evolution of C_(2)H_(4),the carbon amount is positively related to the H_(2)partial pressure,but it shows the highest amount and evolution rate when the ethylene partial pressure is 20%.Based on the reduction rate curves of WO_(3) and carbon evolution rate curves of C_(2)H_(4),the rate equations of pre-reduction and carbon evolution of WO_(3)-Co_(3)O_(4)system at 600℃are established.The pre-reduction reaction belongs to the first-order reaction,and its equation is expressed as follows:r=-(dw_(WO_(3)))/dt=(9±0.15)×10^(-2)×P_(H_(2))^(0.44)P_(C_(2)H_(4))&(0.57)The carbon deposition rate equation of C_(2)H_(4) can be expressed as follows:r=-(dc_C)/dt=r_f-r_b≌7.35×10^(-2)×P_(C_(2)H_(4))^(0.31)

Learning to represent 2D human face with mathematical model

How to represent a human face pattern?While it is presented in a continuous way in human visual system,computers often store and process it in a discrete manner with 2D arrays of pixels.The authors attempt to learn a continuous surface representation for face image with explicit function.First,an explicit model(EmFace)for human face representation is pro-posed in the form of a finite sum of mathematical terms,where each term is an analytic function element.Further,to estimate the unknown parameters of EmFace,a novel neural network,EmNet,is designed with an encoder-decoder structure and trained from massive face images,where the encoder is defined by a deep convolutional neural network and the decoder is an explicit mathematical expression of EmFace.The authors demonstrate that our EmFace represents face image more accurate than the comparison method,with an average mean square error of 0.000888,0.000936,0.000953 on LFW,IARPA Janus Benchmark-B,and IJB-C datasets.Visualisation results show that,EmFace has a higher representation performance on faces with various expressions,postures,and other factors.Furthermore,EmFace achieves reasonable performance on several face image processing tasks,including face image restoration,denoising,and transformation.

High-performance supercapacitors based on free-standing SiC@PEDOT nanowires with robust cycling stability

Conductive polymers as one of the candidate materials with pseudocapacitor behavior have inspired wide attentions,because of their high conductivity,fexibility,low cost and excellent processability.However,the intrinsically poor cycling stability induced by the volume change over the doping/dedoping redox process limits their practical applications.Herein,we report the exploration of electrodes with robust cycling capacity for supercapacitors(SCs),which are rationally designed by coating conductive poly(3,4-ethylenedioxythiophene)(PEDOT)around free-standing SiC nanowires using an all-dry oxidative chemical vaper deposition(oCVD)method.The as-constructed SiC@PEDOT nanowire architecture enables a specific capacitance of 26.53 m F/cm^(2)at 0.2 m A/cm^(2),which is~370%to that of SiC nanowire counterpart(7.04 m F/cm^(2)).Moreover,their aqueous-based SCs exhibit robust cycling stability with104%capacity retention after 10000 cycles,which is among the highest values achieved for PEDOTbased SCs.

Residual Film Pollution in the Eighth Division of the Xinjiang Production and Construction Corps

This study investigated the residual film content and distribution at different soil depths in the Eighth Division of the Xinjiang Production and Construction Corps.Before spring plowing in 2019,representative fields in four areas(Anjihai,Shihezi suburbs,Mosuowan and Xiayedi)were selected for residual film collection.The average content of residual film in the Eighth Division was 104 kg/ha.The residual film content in the four areas decreased in the order Anjihai>Shihezi suburbs>Mosuowan>Xiayedi.The average amount of residual film collected from cotton fields was greater than that from corn fields.Residual film content in the cotton field at soil depths of 0~10 and 10~30 cm was higher than that in the corn field,whereas the residual film content at a 30–50 cm soil depth in the corn field was higher than that in the cotton field.The results showed that farmers do not consider the long-term benefits,the high cost and short time of recycling,and the easy recycling of surface residual film.The shallow that the higher content of residual film,the less water in the soil of cotton.The same time,the results showed that the quantity of residual film in cotton field had greater influence on cotton quality.

Size,composition,and mixing state of individual aerosol particles in a South China coastal city

Aerosol samples were collected in summer in Macao, a coastal city of the Pearl River Delta Region in China. Morphology, size, elemental composition, and mixing state of individual aerosol particles were determined by scanning electron microscopy coupled energy dispersive X-ray （SEM/EDX） and transmission electron microscopy （TEM）. Based on the morphologies of 5711 aerosol particles, they consist of soot （32%）, mineral （17%）, secondary-（22%）, and unknown fine particles （29%）. The sizes of these particles were mostly distributed between 0.1 and 0.4 μm. Compositions of 202 mineral particles were obtained by SEM/EDX. Mineral particles were mainly classified into three types： Si-rich, Ca-rich, and Na-rich. The compositions of typical mineral particles can indicate their sources in sampling location. For example, mineral particles, collected along the main street, were associated with trace amounts of heavy metals, such as Zn, Ti, Mn, Ba, Pb, and As. TEM observations indicate that most Na-rich particles were aged sea salt particles （e.g., Na2SO4 and NaNO3） which formed through heterogeneous chemical reactions between sea salt and acidic gases. Additionally, aging time of soot was short in Macao due to high humidity, high temperature, and high levels of sunlight in Macao. Most of soot and fine mineral dust particles were internally mixed with secondary particles.

Multi-objective optimization of methane production system from biomass through anaerobic digestion

This work addressed the multi-objective optimization of a biogas production system considering both environmental and economic criteria. A mixed integer non-linear programming(MINLP) model was established and solved with non-dominated sorting genetic algorithm Ⅱ, from which the Pareto fronts, the optimal technology combinations and operation conditions were obtained and analyzed. It's found that the system is feasible in both environmental and economic considerations after optimization. The most expensive processing section is decarbonization; the most expensive equipment is anaerobic digester; the most power-consuming processing section is digestion, followed by decarbonization and waste management. The positive green degree value on the process is attributed to processing section of digestion and waste management. 3:1 chicken feces and corn straw, solar energy, pressure swing adsorption and 3:1 chicken feces and rice straw, solar energy, pressure swing adsorption are turned out to be two robust technology combinations under different prices of methane and electricity by sensitivity analysis. The optimization results provide support for optimal design and operation of biogas production system considering environmental and economic objectives.

Highly Dispersive Co@N-C Catalyst as Freestanding Bifunctional Cathode for Flexible and Rechargeable Zinc–air Batteries

The design of efficient cathode with great cycle performance,high flexibility,and low cost is essential for the commercialization of zinc–air battery(ZAB).Herein,we report the exploration of freestanding bifunctional cathode with rationally designed structures,namely,tiny Co nanoparticles embedded in Ndoped carbon nanofiber aerogels,which have desired features including uniform Co dispersity,balanced distribution of N-C species,hierarchically porous structure with increased fraction of meso-to micropores,and moderate amounts of defects.Accordingly,the as-fabricated cathodes exhibit positive half-wave potential of 0.82 V for oxygen reduction and small overpotential of 350 mV at 10 mA cm^(−2) for oxygen evolution,respectively,which deliver smaller reversible oxygen electrode index(0.76 V)than the commercial Pt/C+RuO_(2)(0.80 V)and most Co-based electrocatalysts ever reported.Impressively,the as-constructed liquid rechargeable ZAB behaves high peak power density(160 mW cm^(−2)),large specific capacity(759.7 mAh g^(−1) at 10 mA cm^(−2),tested after 120 h of OCV tests),and robust stability over 277 h.Moreover,the as-assembled quasi-solid-state ZAB using such freestanding cathode represents excellent mechanical flexibility and outstanding cycle performance,regardless of being serviced under extremely bending conditions from 0°to 180°,underscoring their promising applications as durable bifunctional cathode for portable metalair batteries.

Compositional characteristics and toxicological responses of human lung epithelial cells to inhalable particles (PM_(10)) from ten typical biomass fuel combustions

As the primary component of haze,atmospheric inhalable particulate matters(PMio)are highly detri-mental to human health.Biomass combustion is one of China's most pivotal sources to aerosols pollution,inducing non-negligible emissions and uncertain risks.PMio samples directly from 10 representative biomass fuel combustion sources(2 groups covering the reality widely:straws of rice,wheat,corn,corncob,soybean,peanut,rape,sesame;and branches of pine,peach)were collected using the dilution channel sampler and analyzed for chemical compositions and in vitro cytotoxicity to human lung epithelial cell lines A549.The components of PMio are dominated by organic carbon(OC),followed by Water-soluble K+and Cl,and rich in metals Fe,Zn,Cr,and Ni.Generally,PMio emitted from biomass fuel combustions can weaken the antioxidant capacity of cells,and straws emissions,especially rape and peanut straws,show stronger ability to further induce oxidative stress and inflammatory damage than fuelwoods,owing to the key toxic roles of Cr,Ni,and Co.Therefore,reducing the specific source emis--sions of PMio from crop straw combustions rich in heavy metals could be an effective oriented strategy to improve environmental air quality and control aerosols pollution precisely for protecting public health.

Introduction to the special issue on “COVID-19”

COVID-19 pandemic is wreaking havoc and bringing the whole world into a standstill in an unprecedented fashion. Joint efforts from multiple sectors to address the various aspects of environment and public health through usage of green technologies have become essential. The application of cleaner and effective technologies can be expanded to management and control, pollution mitigation and valorization of waste. In this Special Issue of Geoscience Frontiers, we present contributions addressing the interactions of COVID-19 in relation to environment and human health.

Analysis on Content and Distribution of Residual Film in Fields of Different Crops

Before spring ploughing in 2019,the representative fields of the 8^(th) Division were selected,and residual film at different depths of soil in three areas of the 8^(th) Division was collected. Through the analysis on the weight and amount of residual film at different depths of soil,it was found that the average content of residual film in the 8^(th) Division was 104 kg/hm^2. From high to low,the content sequence of residual film in the three areas was Anjihai area,Mosuowan area and Xiayedi area. The average amount of residual film collected from the cotton field in the three areas was greater than that from the corn field. In the three areas,the content of residual film in the cotton field at the depth of 0-10 and 11-30 cm was higher than that in the corn field,while the content of residual film at the depth of 31-50 cm in the corn field was higher than that in the cotton field.

Analysis on the Current Situation, Impact and Source of Atmospheric Ozone Pollution in China

With the gradual improvement of PM 2.5 pollution in China,the problem of ozone pollution is becoming more and more serious.In recent years,ozone has become the only one of the six major air pollutants increasing year on year in China,and the primary pollutant of air pollution in many cities of China in summer.In this paper,pollution characteristics of ozone and its relationship with meteorological conditions in China s provincial capitals and some economically developed cities(27 cities in total),and temporal-spatial distribution rules of ozone in China were analyzed,and influence and main source of ozone in China were summarized.The results were as below:daily change of ozone concentration showed as single-peak type,and the maximum generally appeared at 15:00-16:00,while the minimum generally occurred at 07:00-08:00.Seasonal change of ozone concentration mainly showed as single-peak type.In summer,ozone concentration was the highest,followed by spring and autumn,and its concentration in winter was the lowest.The influence of meteorological factors on ozone showed as that there was significantly positive correlation between ozone and temperature,radiation quantity,and significantly negative correlation between ozone and humidity,NOx.Ozone near surface will have adverse effects on biosphere,climate and ecological environment.The source of ozone can be divided into two kinds:man-made and natural,and the most important source of near-surface ozone is man-made.

Integration of HAZOP and Bayesian network in city gas explosion emergency response processes

City gas explosion accidents have occurred frequently in recent years,leading to major injuries and losses.An effective emergency response process is necessary to deal with city gas accidents by preventing them from expanding and reducing losses.However,emergency response is a complex process that includes many contributing factors,such as personnel,departments,and materials.If one or more of these factors fails,it will affect the implementation of the emergency response.Therefore,more efforts should be made on the systematic procedures and methods addressing risks in emergency response process.From the view of Process Hazard Analysis(PHA),the emergency response process can be seen as a work process with many operation nodes.In this sense,PHA methods such as HAZOP can be used for the risk analysis of the emergency response process.First,the emergency response process of a city gas explosion accident is broken down into procedure-based operations.Then HAZOP is used to comprehensively review the process and obtain deviations,causes,and consequences,which are considered as risk factors.Finally,Bayesian networks are used to characterize the inter relationships of various factors and quantify the risk of the emergency response process.Furthermore,the most critical events can be identified based on the sensitivity analysis.The results show that firefighters'operations,management of the emergency command center,and environmental conditions on site are critical factors during city gas explosion accidents.The method proposed can help identify potential risks of the emergency response process systematically and prevent accident expansion.

Synthesis, mechanical investigation, and application of nitrogen and phosphorus co-doped carbon dots with a high photoluminescent quantum yield

Heteroatom-doped carbon dots （CDs） with a high photoluminescent quantum yield （PLQY） have recently attracted attention due to their applications in chemical sensors, photocatalysis, bioimaging, and drug delivery. Nitrogen and phosphorus are in close proximity to carbon in the periodic table and are key tracking elements in the field of biomedical imaging. These two elements alter the optical and electronic properties of CDs and help improve the fundamental understanding of their PLQY. This can also lead to multifunctional usage in photoimaging and photothermal therapy. However, most PLQYs resulting from the synthesis of P-doped CDs are currently below 50%. These CDs have limited usefulness in the fields of bioimaging and drug delivery. In this study, a single-step, high-efficiency hydrothermal method was applied to synthesize nitrogen and phosphorous-doped carbon dots （（N,P）-CDs） with a PLQY of up to 53.8% with independent emission behavior. Moreover, the CDs presented high monodispersity, robust excitation-independent luminescence, and stability over a large pH range. Spectroscopic investigations indicated that the PLQY of the （N,P）-CDs was primarily due to the addition of P and the passivation effect of the oxidized surface. The excellent fluorescence properties of （N,P）-CDs can be effectively and selectively quenched by Hg2~ ions. Such systems show a linear response in the 0-900 nM concentration range with a short response time, indicating their potential for applications in the fields of chemistry and biology.

Trace metals in atmospheric fine particles in one industrial urban city: Spatial variations, sources, and health implications

Trace metals in PM2.5 were measured at one industrial site and one urban site during September, 2010 in Ji＇nan, eastern China. Individual aerosol particles and PM2.5 samples were collected concurrently at both sites. Mass concentrations of eleven trace metals （i.e., Al, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Sr, Ba, and Pb） and one metalloid （i.e., As） were measured by inductively coupled plasma atomic emission spectroscopy （ICP-AES）. The result shows that mass concentrations of PM2.5 （130μg/m3） and trace metals （4.03 μg/m3） at the industrial site were 1.3 times and 1.7 times higher than those at the urban site, respectively, indicating that industrial activities nearby the city can emit trace metals into the surrounding atmosphere. Fe concentrations were the highest among all the measured trace metals at both sites, with concentrations of 1.04 ixg/m 3 at the urban site and 2.41 Itg/m3 at the industrial site, respectively. In addition, Pb showed the highest enrichment factors at both sites, suggesting the emissions from anthropogenic activities existed around the city. Correlation coefficient analysis and principal component analysis revealed that Cu, Fe, Mn, Pb, and Zn were originated from vehicular traffic and industrial emissions at both sites; As, Cr, and part of Pb from coal-fired power plant; Ba and Ti from natural soil. Based on the transmission electron microscopy analysis, we found that most of the trace metals were internally mixed with secondary sulfate/organic particles. These internally mixed trace metals in the urban air may have different toxic abilities compared with externally mixed trace metals.

Structural and Interfacial Effects on Drug Release Kinetics of Liquid‑Based Fibrous Catheter

Catheterization is indispensable in the field of modern medicine.However,catheter-related thrombosis and infections almost inevitably occur during the process,and as drugs can only be administered at the end of catheter,auxiliary strategies are required for successful implantation.Considering these intractable limitations,a type of self-adaptive,anti-coagulate liquidbased fibrous catheter has been developed.More importantly,it has positional drug release property that traditional catheters desperately need but couldn’t attain.Although enlightening,the feasibility and performance of the positional drug release have only been demonstrated by fluorescents,the specific drug release kinetics remains unknown for adaptation to application scenarios.Therefore,we systematically investigate the structural and interfacial effects of drug molecules and fibrous matrixes on drug release kinetics in a liquid-based fibrous catheter.Theoretical calculations and experiments demonstrate that oleophilic and hydrophilic molecules release slowly due to a dissolution-diffusion mechanism.Amphipathic molecules,however,will significantly affect the gating performance by affecting the interfacial stability,hence they release quickly with emulsifying the gating liquid.Besides the significant impact of molecular properties and interfacial effects,matrix pore size also has a slight influence that molecules release faster in bigger pores.Through this study,the liquid-based fibrous catheter may step further toward practical applications including chemotherapy,haemodialysis,angiography,etc.to overcome the existing catheter-related limitations.

Fine-control-valve of halide perovskite single crystal quality for high performance X-ray detection

Halide perovskite single crystals(HPSCs)provide a unique platform to study the optoelectronic properties of such emerging semiconductor materials,while the temperature induced crystal growth method often has an increased solute integration speed and/or unavoidable solute consumption,resulting in a soaring or slumping crystal growth rate of HPSCs.Here,we developed a universal and facile solvent-vola tilization-limited-growth(SVG)strategy to finely control the crystal growth rate by the fine-control-valve for high quality crystal grown through solution processes.The grown HPSCs by SVG method exhibited a record low trap density of 2.8×10^(8)cm^(-3)and a high charge carrier mobility-lifetime product(μτproduct)of 0.021 cm2/V,indicating the excellent crystal quality.The crystal surface defects were further passivated by oxygen suppliers as Lewis base,which led to a reduction of surface leakage current by two times when using for low dose rate X-ray detection.Such HPSC X-ray detector displayed a high sensitivity of 1274μC/(Gyair cm^(2))with a lowest detectable dose rate of 0.56μGyair/s under 120 keV hard X-ray.Further applications including alloy composition analysis and metal flaw detection by HPSC detectors were also demonstrated,which not only shows the bright future for product quality inspection and non-destructive materials analysis,but also paves the way for growing high quality single crystals and fabricating polycrystalline films.

Red/orange dual-emissive carbon dots for pH sensing and cell imaging

The dual-emissive N,S co-doped carbon dots (N,S-CDs) with a long emission wavelength were synthesized via solvothermal method.The N,S-CDs possess relatively high photoluminescence (PL) quantum yield (QY) (35.7%) towards near-infrared fluorescent peak up to 648 nm.With the advanced characterization techniques including X-ray photoelectron spectroscopy (XPS),Fourier transform infrared spectroscopy (FTIR),etc.It is found that the doped N,S elements play an important role in the formation of high QY CDs.The N,S-CDs exist distinct pH-sensitive feature with reversible fluorescence in a good linear relationship with pH values in the range of 1.0-13.0.What is more,N,S-CDs can be used as an ultrasensitive Ag+ probe sensor with the resolution up to 0.4 μM.This finding will expand the application of as prepared N,S-CDs in sensing and environmental fields.

Effects of tillage managements and maize straw returning on soil microbiome using 16S rDNA sequencing

Agricultural practices could affect bacterial diversity and community structure by altering soil physical and chemical properties. Straw returning and tillage practices are widely used in agriculture, however, the effects of these agricultural practices on microbiomes are still unclear. In the present study, we compared the 18 bacterial communities of soil with different straw returning and tillage treatment combinations. The V3-V4 regions of the 16S ribosomal RNA were amplified and analyzed by high-throughput sequencing technology. The results showed that the bacterial communities were consistently dominated by Acidobacteria, Proteobacteria, Actinobacteria, and Chloroflexi. Short-term straw returning and tillage practices significantly altered the diversity, relative abundance and functions of the soil microbiome. Soil subjected to rotary tillage and straw returning (RTS) combination possessed the highest bacterial diversity and lowest ratio of G+/G- bacteria, indicating that RTS could be an efficient integrated management system to improve microbiome in the short term. Double verifications based on relative abundance and network analysis, revealed close relationships of Mycobacterium and Methylibium with RTS, indicating they could serve as biomarkers for RTS. Investigating microbial changes under different agricultural practices will provide valuable foundations for land sustainable utilization and increase crop yields.

Atmospheric fine particles in a typical coastal port of Yangtze River Delta

In recent decades, coastal ports have experienced rapid development and become an important economic and ecological hub in China. Atmospheric particle is a research hotspot in atmospheric environmental sciences in inland regions. However, few studies on the atmospheric particle were conducted in coastal port areas in China, which indeed suffers atmospheric particle pollution. Lack of the physicochemical characteristics of fine particles serves as an obstacle toward the accurate control for air pollution in the coastal port area in China. Here, a field observation was conducted in an important coastal port city in Yangtze River Delta from March 6 to March 19, 2019. The average PM2.5 concentration was 63.7 ±27.8 μg/m^3 and NO3^-, SO4^2-, NH4^+, and organic matter accounted for ?60% of PM 2.5. Fe was the most abundant trace metal element and V as the ship emission indicator was detected. Transmission electron microscopy images showed that SK-rich, soot, Fe, SK-soot and SK-Fe were the major individual particles in the coastal port. V and soluble Fe were detected in sulfate coating of SK-Fe particles. We found that anthropogenic emissions, marine sea salt, and secondary atmosphere process were the major sources of fine particles. Backward trajectory analysis indicated that the dominant air masses were marine air mass, inland air mass from northern Zhejiang and inland-marine mixed air mass from Shandong and Shanghai during the sampling period. The findings can help us better understand the physicochemical properties of atmospheric fine particles in the coastal port of Eastern China.