The investigations of physical attributes of oceans,including parameters such as heat flow and bathymetry,have garnered substantial attention and are particularly valuable for examining Earth’s thermal structures and...The investigations of physical attributes of oceans,including parameters such as heat flow and bathymetry,have garnered substantial attention and are particularly valuable for examining Earth’s thermal structures and dynamic processes.Nevertheless,classical plate cooling models exhibit disparities when predicting observed heat flow and seafloor depth for extremely young and old lithospheres.Furthermore,a comprehensive analysis of global heat flow predictions and regional ocean heat flow or bathymetry data with physical models has been lacking.In this study,we employed power-law models derived from the singularity theory of fractal density to meticulously fit the latest ocean heat flow and bathymetry.Notably,power-law models offer distinct advantages over traditional plate cooling models,showcasing robust self-similarity,scale invariance,or scaling properties,and providing a better fit to observed data.The outcomes of our singularity analysis concerning heat flow and bathymetry across diverse oceanic regions exhibit a degree of consistency with the global ocean spreading rate model.In addition,we applied the similarity method to predict a higher resolution(0.1°×0.1°)global heat flow map based on the most recent heat flow data and geological/geophysical observables refined through linear correlation analysis.Regions displaying significant disparities between predicted and observed heat flow are closely linked to hydrothermal vent fields and active structures.Finally,combining the actual bathymetry and predicted heat flow with the power-law models allows for the quantitative and comprehensive detection of anomalous regions of ocean subsidence and heat flow,which deviate from traditional plate cooling models.The anomalous regions of subsidence and heat flow show different degrees of anisotropy,providing new ideas and clues for further analysis of ocean topography or hydrothermal circulation of mid-ocean ridges.展开更多
Leveraging big data signal processing offers a pathway to the development of artificial intelligencedriven equipment.The analysis of fluid flow signals and the characterization of fluid flow behavior are of critical i...Leveraging big data signal processing offers a pathway to the development of artificial intelligencedriven equipment.The analysis of fluid flow signals and the characterization of fluid flow behavior are of critical in two-phase flow studies.Significant research efforts have focused on discerning flow regimes using various signal analysis methods.In this review,recent advances in time series signals analysis algorithms for stirred tank reactors have been summarized,and the detailed methodologies are categorized into the frequency domain methods,time-frequency domain methods,and state space methods.The strengths,limitations,and notable findings of each algorithm are highlighted.Additionally,the interrelationships between these methodologies have also been discussed,as well as the present progress achieved in various applications.Future research directions and challenges are also predicted to provide an overview of current research trends in data mining of time series for analyzing flow regimes and chaotic signals.This review offers a comprehensive summary for extracting and characterizing fluid flow behavior and serves as a theoretical reference for optimizing the characterization of chaotic signals in future research endeavors.展开更多
The occurrence of geogenic arsenic(As)in groundwater is a global public health concern.However,there remain large gaps in groundwater As data,making it difficult to identify non-compliant domestic wells,partly due to ...The occurrence of geogenic arsenic(As)in groundwater is a global public health concern.However,there remain large gaps in groundwater As data,making it difficult to identify non-compliant domestic wells,partly due to lack of low-cost methods capable of rapid As analysis.Therefore,the development of high through-put and reliable on-site determination methods for inorganic As is essential.Herein,a portable automated analyzer was developed for the determination of arsenite(As(Ⅲ)),arsenate(As(Ⅴ))and phosphate in As contaminated groundwater based on a previously adapted method for molybdenum blue spectrophotometry.After the optimization of the chemical reactions and flow manifold,the system demonstrated a high sample through-put(4.8/h for As(Ⅲ),As(Ⅴ)and phosphate analysis),allowing this system to screen 125 samples in 24 h.Other advantages include low operational costs(0.3 CNY per sample),appropriate sensitivity for contaminated groundwater(detection limits of 4.7μg/L,8.3μg/L and 5.4μg/L for As(Ⅲ),As(Ⅴ)and phosphate,respectively),good linearity(R^(2)>0.9996 at As concentrations up to 1600μg/L)and high precision(relative standard deviations of 3.5% and 2.8% for As(Ⅲ)and As(Ⅴ),respectively).The portable system was successfully used for As speciation analysis in 5 groundwater samples collected from multi-level wells at Yinchuan Plain,northwestern China,with total As concentrations ranging from 75.7 to 295.0μg/L,independently assessing As speciation,providing a promising novel method for the rapid on-site screening of As in tens of millions of domestic wells worldwide.展开更多
From a life cycle perspective,the material flow analysis is utilized to investigate the lithium material flows in international trade from 2000 to 2019.The results reveal that at the global level,the total volume of l...From a life cycle perspective,the material flow analysis is utilized to investigate the lithium material flows in international trade from 2000 to 2019.The results reveal that at the global level,the total volume of lithium trade grew rapidly,reaching 121116 t in 2019.Lithium trade was dominated by lithium minerals,lithium carbonate and lithium hydroxide rather than final lithium products,indicating an immaturity in global lithium industry.At the intercontinental level,Asia’s import trade and Oceania’s export trade led the world,accounting for 81.22%and 39.68%,respectively.At the national level,China,Japan and Korea became the main importers,while Chile and Australia were the main exporters.In addition,China’s trade volume far exceeded that of the United States.China’s exports were dominated by lithium-ion batteries,while the United States mainly imported lithium-ion batteries,proving that the development of China’s lithium industry was relatively faster.展开更多
To accurately acquire deep-sea live biological samples,a hydraulic suction macro-biological pressure-retaining sampler(HSMPS)was designed to achieve active capture of seafloor biological by a suction pump.The complex ...To accurately acquire deep-sea live biological samples,a hydraulic suction macro-biological pressure-retaining sampler(HSMPS)was designed to achieve active capture of seafloor biological by a suction pump.The complex flow fields of deep-sea biologicals at three different locations were simulated.The deep-sea biologicals cause the flow field pressure and velocity to rise at different locations of the sampler,and the magnitude of the rise varies at different locations.The internal flow properties of the sampler were analyzed for different pumping flow rates the sampler.When the flow rate of the sampler pump was greater than 14 m3/h,the velocity of the inlet of the inflow area was greater than the limiting velocity of the deep-sea biologicals.The pumping test of deep-sea biologicals pumping sampler was carried out in the laboratory,and the test results were basically consistent with the simulation analysis.In order to balance the deep-sea biologicals damage and escape rate,the pumping flow of the sampler should be controlled between 14 and 16 m3/h.The test results provide a theoretical basis for the design of deep-sea biologicals sampling equipment.展开更多
This study assesses the potential and benefits of reducing plastic consumption at the institutional level by taking the Beijing Institute of Petrochemical Technology(BIPT)in China as the case.By tracking the plastic m...This study assesses the potential and benefits of reducing plastic consumption at the institutional level by taking the Beijing Institute of Petrochemical Technology(BIPT)in China as the case.By tracking the plastic material flow on the BIPT campus,we provide insights into the efforts required to achieve a plastic-free campus.A mixed-methods approach was employed,encompassing material flow analysis,quantitative analysis of influencing factors,examination of best practices in universities,and market price-based valuation of plastic reduction.The main conclusions are as follows:(1)Each student consumed an average of 9.2 kg of plastics for daily use on BIPT campus in the base year of 2020,with campus canteens,off-campus cafés,and shops(offline and online)contributing to 36%,31%and 30%respectively.(2)BIPT has a reduction potential of 45%,equivalent to 4.1 kg per student annually,yielding benefits of 45 RMB from savings in oil material and production energy,avoiding plastic waste,and reducing carbon emission.(3)If all global tertiary institutions set a target of reducing plastics by 4.1 kg per student,1.94 Mt of plastics could be avoided by 2035.(4)Greater reductions and benefits could be achieved if tertiary institutions extend their efforts across all campus activities,with substantial indirect and long-term contributions ranging from more sustainable campus management to fostering a transition towards a green economy.These findings highlight that plastic-free initiatives require contextual construction and environmental education both on and off campus.展开更多
This paper presents a sensitivity analysis method for analyzing the key factors affecting the stability problem of the transonic compressors.The adjoint method is integrated into the meridional stability model,a linea...This paper presents a sensitivity analysis method for analyzing the key factors affecting the stability problem of the transonic compressors.The adjoint method is integrated into the meridional stability model,a linear stability prediction model utilized to analyze the flow stability problem of the compressor,and the sensitivity analysis method is further developed for the flow stability problem of the compressor.The study selects the NASA Rot or 37,a transonic compressor,as the research object to verify the proposed method and explore the sensitive factors leading to the stall inception.The results of sensitivity analysis to both the flow parameters and the external source terms reveal that the stall inception is sensitive to the base flow field at the rotor tip and the stability margin of the compressor can be enhanced by improving the flow field at this region.Physical explanations are presented and discussed to correlate the three-dimensional flow field to the results obtained via the employed analysis method,which shows that flow structures and characteristics near the end-wall region,especially the tip leakage flow or the tip leakage vortex and its interaction with the shock wave,contribute to the stall inception.展开更多
With the acceleration of industrialization and urbanization,ammonia nitrogen pollution in water bodies has become increasingly severe,making the development of efficient and low-consumption wastewater treatment tech-n...With the acceleration of industrialization and urbanization,ammonia nitrogen pollution in water bodies has become increasingly severe,making the development of efficient and low-consumption wastewater treatment tech-nologies highly significant.This study employs three-dimensional computational fluid dynamics(CFD)to investigate the cavitation mechanisms and flow field characteristics in a novel jet impingement-negative pressure ammonia removal reactor.The simulation,validated by experimental pressure data with a high degree of consistency,utilizes the Mixture model,the Realizable k-εturbulence model,and the Schnerr-Sauer cavitation model.The results demonstrate that the flow velocity undergoes a substantial acceleration within the orifice nozzle,triggering a dramatic pressure drop from an inlet value of approximately 1.17 MPa to below the saturated vapor pressure,reaching as low as−109 kPa,which induces intense cavitation.Cavitation bubbles primarily originate on the inner wall of the nozzle,with the vapor volume fraction peaking at about 0.42 within the orifice.A strong positive correlation was observed between the local vapor fraction and the flow velocity,indicating that cavitation enhances jet intensity.Furthermore,vortex structures near the wall and within the jacket sustain low-pressure zones,facilitating continuous cavitation and efficient mixing.This study quantitatively elucidates the cavitation dynamics and its interplay with the flow field,providing a solid theoretical and numerical basis for optimizing the reactor design to enhance ammonia removal efficiency.展开更多
This article presents a mathematical model addressing a scenario involving a hybrid nanofluid flow between two infinite parallel plates.One plate remains stationary,while the other moves downward at a squeezing veloci...This article presents a mathematical model addressing a scenario involving a hybrid nanofluid flow between two infinite parallel plates.One plate remains stationary,while the other moves downward at a squeezing velocity.The space between these plates contains a Darcy-Forchheimer porous medium.A mixture of water-based fluid with gold(Au)and silicon dioxide(Si O2)nanoparticles is formulated.In contrast to the conventional Fourier's heat flux equation,this study employs the Cattaneo-Christov heat flux equation.A uniform magnetic field is applied perpendicular to the flow direction,invoking magnetohydrodynamic(MHD)effects.Further,the model accounts for Joule heating,which is the heat generated when an electric current passes through the fluid.The problem is solved via NDSolve in MATHEMATICA.Numerical and statistical analyses are conducted to provide insights into the behavior of the nanomaterials between the parallel plates with respect to the flow,energy transport,and skin friction.The findings of this study have potential applications in enhancing cooling systems and optimizing thermal management strategies.It is observed that the squeezing motion generates additional pressure gradients within the fluid,which enhances the flow rate but reduces the frictional drag.Consequently,the fluid is pushed more vigorously between the plates,increasing the flow velocity.As the fluid experiences higher flow rates due to the increased squeezing effect,it spends less time in the region between the plates.The thermal relaxation,however,abruptly changes the temperature,leading to a decrease in the temperature fluctuations.展开更多
The chemiluminescence reactions between lucigenin and reductants such as Mo(LII),V( II), U(III), W(III), Cr(II), Ti(III) and Fe( II), which were produced on-line by passing Mo(VI),V(V),U(VI), W(VI), Cr(VI,III),Ti(IV) ...The chemiluminescence reactions between lucigenin and reductants such as Mo(LII),V( II), U(III), W(III), Cr(II), Ti(III) and Fe( II), which were produced on-line by passing Mo(VI),V(V),U(VI), W(VI), Cr(VI,III),Ti(IV) and Fe(III) through a micro Jones column, are studied in detail. Results show that the reactions can be used directly for the determination of these substances. The mechanism of the reactions is also investigated.展开更多
Poly（pheniothiazine） films were prepared on a porous carbon felt（CF） electrode surface by an electrooxidative polymerization of three phenothiazine derivatives（i.e.,Tthionine（TN）,Toluidine Blue（TB） and Methyl...Poly（pheniothiazine） films were prepared on a porous carbon felt（CF） electrode surface by an electrooxidative polymerization of three phenothiazine derivatives（i.e.,Tthionine（TN）,Toluidine Blue（TB） and Methylene Blue（MB）） from 0.1 mol/L phosphate buffer solution（pH 7.0）.Among the three phenothiazies,the poly（TB） film-modified CF exhibited an excellent electrocatalytic activity for the oxidation of nicotinamide adenine dinucleotide reduced form（NADH） at ＋0.2 V vs.Ag/AgCl.The poly（TB） film-modified CF was successfully used as working electrode unit of highly sensitive amperometric flow-through detector for NADH.The peak currents（peak heights） were almost unchanged,irrespective of a carrier flow rate ranging from 2.0 to 4.1 mL/min,resulting in the measurement of NADH（ca.30 samples/hr） at 4.1 mL/min.The peak current responses of NADH showed linear relationship over the concentration range from 1 to 30 μmol/L（sensitivity：0.318 μA/（μmol/L）;correlation coefficient：0.997）.The lower detection limit was found to be 0.3 μmol/L（S/N = 3）.展开更多
A dynamic transient flow analysis method considering complex factors such as the cyclic injection and production history in a gas field storage facility was established in view of the limitations of the existing metho...A dynamic transient flow analysis method considering complex factors such as the cyclic injection and production history in a gas field storage facility was established in view of the limitations of the existing methods for transient flow analysis and the characteristics of the injection-production operation of strongly heterogeneous gas reservoirs, and the corresponding theoretical charts were drawn. In addition, an injection-production dynamic transient flow analysis model named "three points and two stages" suitable for an underground gas storage(UGS) well with alternate working conditions was proposed. The "three points" refer to three time points during cyclic injection and production, namely, the starting point of gas injection for UGS construction, the beginning and ending points of the injection-production analysis stage;and the "two stages" refer to historical flow stage and injection-production analysis stage. The study shows that the dimensionless pseudo-pressure and dimensionless pseudo-pressure integral curves of UGS well flex downward in the early stage of the injection and production process, and the dimensionless pseudo-pressure integral derivative curve is convex during the gas production period and concave during the gas injection period, and the curves under different flow histories have atypical features. The new method present in this paper can analyze transient flow of UGS accurately. The application of this method to typical wells in Hutubi gas storage shows that the new method can fit the pressure history accurately, and obtain reliable parameters and results.展开更多
A stopped-flow reversed flow injection method for the determination of free cyanide is proposed. Pyridine-barbituric acid mixture is injected in the flow system as reagent to form the colour species with cyanide. The ...A stopped-flow reversed flow injection method for the determination of free cyanide is proposed. Pyridine-barbituric acid mixture is injected in the flow system as reagent to form the colour species with cyanide. The flow is stopped when the reagent zone comes in the flow cell, where absorbance-time data are collected at 580nm wavelength. The linear range of the determination is 0.1 -10μg/ml CN-. The sampling rate is 60h-1 and the relative standard deviation is 1.6% (n=16) at 5.0 μg/ml CN-1 level. With satisfactory results, the proposed method was applied to the determination of free cyanide in wastewater without sample pretreatment.展开更多
A simple and sensitive flow injection method is presented for the determination of histidine based on its enhancement of electrogenerated chemiluminescence (ECL) of luminol. After optimization of the experimental para...A simple and sensitive flow injection method is presented for the determination of histidine based on its enhancement of electrogenerated chemiluminescence (ECL) of luminol. After optimization of the experimental parameters, the working range for histidine was in 1.0 x 10-6 to 1.0 x 10 -3 mol/L with a detection limit (S/N = 3) of 0.56 mmol/L. The relative standard deviation was 1.6% for 11 measurements of 5 x 10 5 mol/L histidine solution. The proposed method has been successfully applied to the determination of histidine in real pharmaceutical preparation.展开更多
Sulfur dioxide has been found to decrease the chemiluminescence of luminol-iodine system.A new determination method for sulfur dioxide in atmosphere is developed by applying this reaction to a flow injection gas diffu...Sulfur dioxide has been found to decrease the chemiluminescence of luminol-iodine system.A new determination method for sulfur dioxide in atmosphere is developed by applying this reaction to a flow injection gas diffusion separation system.This permits the determination of sulfur dioxide selectively and rapidly.展开更多
Present study describes the development of a rapid, sensitive and selective flow injection analysis of hydrazine in the aqueous streams of purex process by liquid chromatography system coupled with UV-Visible detector...Present study describes the development of a rapid, sensitive and selective flow injection analysis of hydrazine in the aqueous streams of purex process by liquid chromatography system coupled with UV-Visible detector. The method is based on the formation of yellow coloured azine complex by reaction of hydrazine with para-dimethy laminobenzaldehyde (pDMAB). The formed yellow coloured complex is stable in acidic medium and has a maximum absorption at 460 nm. The presence of uranium in hydrazine solution is not interfering in the analysis. Under optimum condition, the absorption intensity linearly increased with the concentration of hydrazine in the range from 0.05-10 mg?L–1 with a correlation coefficient of R2=0.9999 (n=7). The experimental detection limit is 0.05mgL–1. The sampling frequency is 15 samples h–1 and the relative standard deviation was 2.1% for 0.05 mg?L–1. This method is suitable for automatic and continuous analysis and successfully applied to determine the concentration of hydrazine in the aqueous stream of nuclear fuel reprocessing.展开更多
The flow characteristics of shell-side fluid in the tube-and-shell heat exchangers with trisection helical baffles with 35° inclined angles are numerically analyzed. The secondary flow distribution of the fluid i...The flow characteristics of shell-side fluid in the tube-and-shell heat exchangers with trisection helical baffles with 35° inclined angles are numerically analyzed. The secondary flow distribution of the fluid in the shell-side channel is focused on. The results on meridian planes indicate that in the shell-side channel, the center part of fluid has an outward tendency because of the centrifugal force, and the peripheral region fluid has an inward tendency under the centripetal force. So in a spiral cycle, the fluid is divided into the upper and lower beams of streamlines, at the same time the Dean vortices are formed near the left baffle, and then the fluid turns to centripetal flow near the right baffle. Finally the two beams of streamlines merge in the main flow. The results of a number of parallel slices between two parallel baffles with the same sector in a swirl cycle also show the existence of the secondary flow and some backward flows at the V-gaps of the adjacent baffles. The secondary flows have a positive effect on mixing fluid by promoting the momentum and mass exchange between fluid particles near the tube wall and in the main stream, and thus they will enhance the heat transfer of the helix heat exchanger.展开更多
A simple, rapid and sensitive flow injection chemiluminescence （FI-CL） method has been developed for the determination of meloxicam. The method is based on the CL-emitting reaction between meloxicam and potassium pe...A simple, rapid and sensitive flow injection chemiluminescence （FI-CL） method has been developed for the determination of meloxicam. The method is based on the CL-emitting reaction between meloxicam and potassium permanganate in a hydrochloric acid medium, enhanced by formaldehyde （HCHO）. Under optimum conditions, calibration curve over the range of 1.0-20.0μg/mL was obtained. The proposed method was successfully applied to the determination of meloxicam in capsules with no evi- dence of interference from common excipients. The detection limit of this method was 25.6 ng/mL. The relative standard deviation was 2.1% for 10.0 μg/mL meloxicam. The sample throughput was found to be 120 samples/h.展开更多
Substance flow analysis was applied to analyzing the lead emissions in 2010. It turns out that in 2010, for every 1 kg of lead consumed, 0.48 kg lead is lost into the environment. The emissions in 2010 were estimated ...Substance flow analysis was applied to analyzing the lead emissions in 2010. It turns out that in 2010, for every 1 kg of lead consumed, 0.48 kg lead is lost into the environment. The emissions in 2010 were estimated to be 1.89×10^6 t, which were mainly from use （39.20%） and waste management＆recycling （33.13%）. The accumulative lead in 1960-2010 from the anthropogenic flow was estimated and the results show that the total accumulative lead in this period amounted to 19.54×10^6 t, which was equivalent to 14.26 kg and 2.04 g/m^2 at the present population and territory.展开更多
基金supported by the Guangdong Province Introduced Innovative R&D Team of Big Data-Mathematical Earth Sciences and Extreme Geological Events Team(grant number 2021ZT09H399)the National Natural Science Foundation of China(grant number 42430111,42050103).
文摘The investigations of physical attributes of oceans,including parameters such as heat flow and bathymetry,have garnered substantial attention and are particularly valuable for examining Earth’s thermal structures and dynamic processes.Nevertheless,classical plate cooling models exhibit disparities when predicting observed heat flow and seafloor depth for extremely young and old lithospheres.Furthermore,a comprehensive analysis of global heat flow predictions and regional ocean heat flow or bathymetry data with physical models has been lacking.In this study,we employed power-law models derived from the singularity theory of fractal density to meticulously fit the latest ocean heat flow and bathymetry.Notably,power-law models offer distinct advantages over traditional plate cooling models,showcasing robust self-similarity,scale invariance,or scaling properties,and providing a better fit to observed data.The outcomes of our singularity analysis concerning heat flow and bathymetry across diverse oceanic regions exhibit a degree of consistency with the global ocean spreading rate model.In addition,we applied the similarity method to predict a higher resolution(0.1°×0.1°)global heat flow map based on the most recent heat flow data and geological/geophysical observables refined through linear correlation analysis.Regions displaying significant disparities between predicted and observed heat flow are closely linked to hydrothermal vent fields and active structures.Finally,combining the actual bathymetry and predicted heat flow with the power-law models allows for the quantitative and comprehensive detection of anomalous regions of ocean subsidence and heat flow,which deviate from traditional plate cooling models.The anomalous regions of subsidence and heat flow show different degrees of anisotropy,providing new ideas and clues for further analysis of ocean topography or hydrothermal circulation of mid-ocean ridges.
基金the National Natural Science Foundation of China(22078030)the National Key Research and Development Project(2019YFC1905802,2022YFB3504305)+1 种基金the Joint Funds of the National Natural Science Foundation of China(U1802255,CSTB2022NSCQ-LZX0014)the Key Project of Independent Research Project of State Key Laboratory of Coal Mine Disaster Dynamics and Control(2011DA105287-zd201902).
文摘Leveraging big data signal processing offers a pathway to the development of artificial intelligencedriven equipment.The analysis of fluid flow signals and the characterization of fluid flow behavior are of critical in two-phase flow studies.Significant research efforts have focused on discerning flow regimes using various signal analysis methods.In this review,recent advances in time series signals analysis algorithms for stirred tank reactors have been summarized,and the detailed methodologies are categorized into the frequency domain methods,time-frequency domain methods,and state space methods.The strengths,limitations,and notable findings of each algorithm are highlighted.Additionally,the interrelationships between these methodologies have also been discussed,as well as the present progress achieved in various applications.Future research directions and challenges are also predicted to provide an overview of current research trends in data mining of time series for analyzing flow regimes and chaotic signals.This review offers a comprehensive summary for extracting and characterizing fluid flow behavior and serves as a theoretical reference for optimizing the characterization of chaotic signals in future research endeavors.
基金supported by the Natural Science Foundation of Fujian Province(No.2020J06008)for Distinguished Young Scholarsthe Fujian Provincial Central Guided Local Science and Technology Development Special Project(No.2022L3078).
文摘The occurrence of geogenic arsenic(As)in groundwater is a global public health concern.However,there remain large gaps in groundwater As data,making it difficult to identify non-compliant domestic wells,partly due to lack of low-cost methods capable of rapid As analysis.Therefore,the development of high through-put and reliable on-site determination methods for inorganic As is essential.Herein,a portable automated analyzer was developed for the determination of arsenite(As(Ⅲ)),arsenate(As(Ⅴ))and phosphate in As contaminated groundwater based on a previously adapted method for molybdenum blue spectrophotometry.After the optimization of the chemical reactions and flow manifold,the system demonstrated a high sample through-put(4.8/h for As(Ⅲ),As(Ⅴ)and phosphate analysis),allowing this system to screen 125 samples in 24 h.Other advantages include low operational costs(0.3 CNY per sample),appropriate sensitivity for contaminated groundwater(detection limits of 4.7μg/L,8.3μg/L and 5.4μg/L for As(Ⅲ),As(Ⅴ)and phosphate,respectively),good linearity(R^(2)>0.9996 at As concentrations up to 1600μg/L)and high precision(relative standard deviations of 3.5% and 2.8% for As(Ⅲ)and As(Ⅴ),respectively).The portable system was successfully used for As speciation analysis in 5 groundwater samples collected from multi-level wells at Yinchuan Plain,northwestern China,with total As concentrations ranging from 75.7 to 295.0μg/L,independently assessing As speciation,providing a promising novel method for the rapid on-site screening of As in tens of millions of domestic wells worldwide.
基金supported by the National Natural Science Foundation of China(Nos.71671187,71874210,71633006)the Natural Science Foundation of Hunan Province,China(No.2024JJ6539)+1 种基金the National Social Science Fund of China(No.22&ZD098)the Social Sciences Fund of Hunan Province,China(No.24YBQ138)。
文摘From a life cycle perspective,the material flow analysis is utilized to investigate the lithium material flows in international trade from 2000 to 2019.The results reveal that at the global level,the total volume of lithium trade grew rapidly,reaching 121116 t in 2019.Lithium trade was dominated by lithium minerals,lithium carbonate and lithium hydroxide rather than final lithium products,indicating an immaturity in global lithium industry.At the intercontinental level,Asia’s import trade and Oceania’s export trade led the world,accounting for 81.22%and 39.68%,respectively.At the national level,China,Japan and Korea became the main importers,while Chile and Australia were the main exporters.In addition,China’s trade volume far exceeded that of the United States.China’s exports were dominated by lithium-ion batteries,while the United States mainly imported lithium-ion batteries,proving that the development of China’s lithium industry was relatively faster.
基金Supported by National Key Research and Development Program of China(Grant Nos.2023YFC2809304,2022YFC2805904)National Natural Science Foundation of China(Grant No.52275106)Special Project for the Construction of Innovative City in Xiangtan of China(Grant No.ZX-ZD20221005).
文摘To accurately acquire deep-sea live biological samples,a hydraulic suction macro-biological pressure-retaining sampler(HSMPS)was designed to achieve active capture of seafloor biological by a suction pump.The complex flow fields of deep-sea biologicals at three different locations were simulated.The deep-sea biologicals cause the flow field pressure and velocity to rise at different locations of the sampler,and the magnitude of the rise varies at different locations.The internal flow properties of the sampler were analyzed for different pumping flow rates the sampler.When the flow rate of the sampler pump was greater than 14 m3/h,the velocity of the inlet of the inflow area was greater than the limiting velocity of the deep-sea biologicals.The pumping test of deep-sea biologicals pumping sampler was carried out in the laboratory,and the test results were basically consistent with the simulation analysis.In order to balance the deep-sea biologicals damage and escape rate,the pumping flow of the sampler should be controlled between 14 and 16 m3/h.The test results provide a theoretical basis for the design of deep-sea biologicals sampling equipment.
基金funded by Key Project of Education and Teaching Reform and Research at Beijing Institute of Petrochemical Technology(ZD20200508).
文摘This study assesses the potential and benefits of reducing plastic consumption at the institutional level by taking the Beijing Institute of Petrochemical Technology(BIPT)in China as the case.By tracking the plastic material flow on the BIPT campus,we provide insights into the efforts required to achieve a plastic-free campus.A mixed-methods approach was employed,encompassing material flow analysis,quantitative analysis of influencing factors,examination of best practices in universities,and market price-based valuation of plastic reduction.The main conclusions are as follows:(1)Each student consumed an average of 9.2 kg of plastics for daily use on BIPT campus in the base year of 2020,with campus canteens,off-campus cafés,and shops(offline and online)contributing to 36%,31%and 30%respectively.(2)BIPT has a reduction potential of 45%,equivalent to 4.1 kg per student annually,yielding benefits of 45 RMB from savings in oil material and production energy,avoiding plastic waste,and reducing carbon emission.(3)If all global tertiary institutions set a target of reducing plastics by 4.1 kg per student,1.94 Mt of plastics could be avoided by 2035.(4)Greater reductions and benefits could be achieved if tertiary institutions extend their efforts across all campus activities,with substantial indirect and long-term contributions ranging from more sustainable campus management to fostering a transition towards a green economy.These findings highlight that plastic-free initiatives require contextual construction and environmental education both on and off campus.
基金supported by the National Natural Science Foundation of China(Nos.52306036,52325602 and U2441279)the National Science and Technology Major Project,China(Nos.Y2022-Ⅱ-0003-0006 and Y2022-Ⅱ-0002-0005)supported by the Project of National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics,China(Nos.6142702200101 and 2024-CXPT-GF-JJ-88-0103)。
文摘This paper presents a sensitivity analysis method for analyzing the key factors affecting the stability problem of the transonic compressors.The adjoint method is integrated into the meridional stability model,a linear stability prediction model utilized to analyze the flow stability problem of the compressor,and the sensitivity analysis method is further developed for the flow stability problem of the compressor.The study selects the NASA Rot or 37,a transonic compressor,as the research object to verify the proposed method and explore the sensitive factors leading to the stall inception.The results of sensitivity analysis to both the flow parameters and the external source terms reveal that the stall inception is sensitive to the base flow field at the rotor tip and the stability margin of the compressor can be enhanced by improving the flow field at this region.Physical explanations are presented and discussed to correlate the three-dimensional flow field to the results obtained via the employed analysis method,which shows that flow structures and characteristics near the end-wall region,especially the tip leakage flow or the tip leakage vortex and its interaction with the shock wave,contribute to the stall inception.
基金supported by Chongqing Natural Science Foundation Innovation and Development Joint Fund(CSTB2023NSCQ-LZX0095)Chongqing Natural Science Foundation General Project(CSTB2025NSCQ-GPX0955)+3 种基金Science and Technology Research Program of Chongqing Municipal Education Commission of China(KJQN202401157)The Open and Innovation Fund of Hubei Three Gorges Laboratory(SK250005)The Key Laboratory of Manufacturing and Application of Intelligent Well Control for Oil and Gas Production and Transportation of Luzhou(2024LZOGB-05)postgraduate Innovation Project of Chongqing University of Technology(CYS240709).
文摘With the acceleration of industrialization and urbanization,ammonia nitrogen pollution in water bodies has become increasingly severe,making the development of efficient and low-consumption wastewater treatment tech-nologies highly significant.This study employs three-dimensional computational fluid dynamics(CFD)to investigate the cavitation mechanisms and flow field characteristics in a novel jet impingement-negative pressure ammonia removal reactor.The simulation,validated by experimental pressure data with a high degree of consistency,utilizes the Mixture model,the Realizable k-εturbulence model,and the Schnerr-Sauer cavitation model.The results demonstrate that the flow velocity undergoes a substantial acceleration within the orifice nozzle,triggering a dramatic pressure drop from an inlet value of approximately 1.17 MPa to below the saturated vapor pressure,reaching as low as−109 kPa,which induces intense cavitation.Cavitation bubbles primarily originate on the inner wall of the nozzle,with the vapor volume fraction peaking at about 0.42 within the orifice.A strong positive correlation was observed between the local vapor fraction and the flow velocity,indicating that cavitation enhances jet intensity.Furthermore,vortex structures near the wall and within the jacket sustain low-pressure zones,facilitating continuous cavitation and efficient mixing.This study quantitatively elucidates the cavitation dynamics and its interplay with the flow field,providing a solid theoretical and numerical basis for optimizing the reactor design to enhance ammonia removal efficiency.
文摘This article presents a mathematical model addressing a scenario involving a hybrid nanofluid flow between two infinite parallel plates.One plate remains stationary,while the other moves downward at a squeezing velocity.The space between these plates contains a Darcy-Forchheimer porous medium.A mixture of water-based fluid with gold(Au)and silicon dioxide(Si O2)nanoparticles is formulated.In contrast to the conventional Fourier's heat flux equation,this study employs the Cattaneo-Christov heat flux equation.A uniform magnetic field is applied perpendicular to the flow direction,invoking magnetohydrodynamic(MHD)effects.Further,the model accounts for Joule heating,which is the heat generated when an electric current passes through the fluid.The problem is solved via NDSolve in MATHEMATICA.Numerical and statistical analyses are conducted to provide insights into the behavior of the nanomaterials between the parallel plates with respect to the flow,energy transport,and skin friction.The findings of this study have potential applications in enhancing cooling systems and optimizing thermal management strategies.It is observed that the squeezing motion generates additional pressure gradients within the fluid,which enhances the flow rate but reduces the frictional drag.Consequently,the fluid is pushed more vigorously between the plates,increasing the flow velocity.As the fluid experiences higher flow rates due to the increased squeezing effect,it spends less time in the region between the plates.The thermal relaxation,however,abruptly changes the temperature,leading to a decrease in the temperature fluctuations.
文摘The chemiluminescence reactions between lucigenin and reductants such as Mo(LII),V( II), U(III), W(III), Cr(II), Ti(III) and Fe( II), which were produced on-line by passing Mo(VI),V(V),U(VI), W(VI), Cr(VI,III),Ti(IV) and Fe(III) through a micro Jones column, are studied in detail. Results show that the reactions can be used directly for the determination of these substances. The mechanism of the reactions is also investigated.
基金financially supported in part by the Open Research Center Project of the Ministry of Education,Science and Culture of Japan
文摘Poly（pheniothiazine） films were prepared on a porous carbon felt（CF） electrode surface by an electrooxidative polymerization of three phenothiazine derivatives（i.e.,Tthionine（TN）,Toluidine Blue（TB） and Methylene Blue（MB）） from 0.1 mol/L phosphate buffer solution（pH 7.0）.Among the three phenothiazies,the poly（TB） film-modified CF exhibited an excellent electrocatalytic activity for the oxidation of nicotinamide adenine dinucleotide reduced form（NADH） at ＋0.2 V vs.Ag/AgCl.The poly（TB） film-modified CF was successfully used as working electrode unit of highly sensitive amperometric flow-through detector for NADH.The peak currents（peak heights） were almost unchanged,irrespective of a carrier flow rate ranging from 2.0 to 4.1 mL/min,resulting in the measurement of NADH（ca.30 samples/hr） at 4.1 mL/min.The peak current responses of NADH showed linear relationship over the concentration range from 1 to 30 μmol/L（sensitivity：0.318 μA/（μmol/L）;correlation coefficient：0.997）.The lower detection limit was found to be 0.3 μmol/L（S/N = 3）.
基金Supported by the CNPC Major Scientific and Technological Project(2019B-3204)PetroChina Major Scientific and Technological Project(kt2020-16-01)。
文摘A dynamic transient flow analysis method considering complex factors such as the cyclic injection and production history in a gas field storage facility was established in view of the limitations of the existing methods for transient flow analysis and the characteristics of the injection-production operation of strongly heterogeneous gas reservoirs, and the corresponding theoretical charts were drawn. In addition, an injection-production dynamic transient flow analysis model named "three points and two stages" suitable for an underground gas storage(UGS) well with alternate working conditions was proposed. The "three points" refer to three time points during cyclic injection and production, namely, the starting point of gas injection for UGS construction, the beginning and ending points of the injection-production analysis stage;and the "two stages" refer to historical flow stage and injection-production analysis stage. The study shows that the dimensionless pseudo-pressure and dimensionless pseudo-pressure integral curves of UGS well flex downward in the early stage of the injection and production process, and the dimensionless pseudo-pressure integral derivative curve is convex during the gas production period and concave during the gas injection period, and the curves under different flow histories have atypical features. The new method present in this paper can analyze transient flow of UGS accurately. The application of this method to typical wells in Hutubi gas storage shows that the new method can fit the pressure history accurately, and obtain reliable parameters and results.
基金This study was supported by the National Natural Science Foundation of China
文摘A stopped-flow reversed flow injection method for the determination of free cyanide is proposed. Pyridine-barbituric acid mixture is injected in the flow system as reagent to form the colour species with cyanide. The flow is stopped when the reagent zone comes in the flow cell, where absorbance-time data are collected at 580nm wavelength. The linear range of the determination is 0.1 -10μg/ml CN-. The sampling rate is 60h-1 and the relative standard deviation is 1.6% (n=16) at 5.0 μg/ml CN-1 level. With satisfactory results, the proposed method was applied to the determination of free cyanide in wastewater without sample pretreatment.
文摘A simple and sensitive flow injection method is presented for the determination of histidine based on its enhancement of electrogenerated chemiluminescence (ECL) of luminol. After optimization of the experimental parameters, the working range for histidine was in 1.0 x 10-6 to 1.0 x 10 -3 mol/L with a detection limit (S/N = 3) of 0.56 mmol/L. The relative standard deviation was 1.6% for 11 measurements of 5 x 10 5 mol/L histidine solution. The proposed method has been successfully applied to the determination of histidine in real pharmaceutical preparation.
文摘Sulfur dioxide has been found to decrease the chemiluminescence of luminol-iodine system.A new determination method for sulfur dioxide in atmosphere is developed by applying this reaction to a flow injection gas diffusion separation system.This permits the determination of sulfur dioxide selectively and rapidly.
文摘Present study describes the development of a rapid, sensitive and selective flow injection analysis of hydrazine in the aqueous streams of purex process by liquid chromatography system coupled with UV-Visible detector. The method is based on the formation of yellow coloured azine complex by reaction of hydrazine with para-dimethy laminobenzaldehyde (pDMAB). The formed yellow coloured complex is stable in acidic medium and has a maximum absorption at 460 nm. The presence of uranium in hydrazine solution is not interfering in the analysis. Under optimum condition, the absorption intensity linearly increased with the concentration of hydrazine in the range from 0.05-10 mg?L–1 with a correlation coefficient of R2=0.9999 (n=7). The experimental detection limit is 0.05mgL–1. The sampling frequency is 15 samples h–1 and the relative standard deviation was 2.1% for 0.05 mg?L–1. This method is suitable for automatic and continuous analysis and successfully applied to determine the concentration of hydrazine in the aqueous stream of nuclear fuel reprocessing.
基金The National Natural Science Foundation of China (No.50976022)the National Key Technology R&D Program of China during the 11th Five-Year Plan Period (No.2008BAJ12B02)
文摘The flow characteristics of shell-side fluid in the tube-and-shell heat exchangers with trisection helical baffles with 35° inclined angles are numerically analyzed. The secondary flow distribution of the fluid in the shell-side channel is focused on. The results on meridian planes indicate that in the shell-side channel, the center part of fluid has an outward tendency because of the centrifugal force, and the peripheral region fluid has an inward tendency under the centripetal force. So in a spiral cycle, the fluid is divided into the upper and lower beams of streamlines, at the same time the Dean vortices are formed near the left baffle, and then the fluid turns to centripetal flow near the right baffle. Finally the two beams of streamlines merge in the main flow. The results of a number of parallel slices between two parallel baffles with the same sector in a swirl cycle also show the existence of the secondary flow and some backward flows at the V-gaps of the adjacent baffles. The secondary flows have a positive effect on mixing fluid by promoting the momentum and mass exchange between fluid particles near the tube wall and in the main stream, and thus they will enhance the heat transfer of the helix heat exchanger.
文摘A simple, rapid and sensitive flow injection chemiluminescence （FI-CL） method has been developed for the determination of meloxicam. The method is based on the CL-emitting reaction between meloxicam and potassium permanganate in a hydrochloric acid medium, enhanced by formaldehyde （HCHO）. Under optimum conditions, calibration curve over the range of 1.0-20.0μg/mL was obtained. The proposed method was successfully applied to the determination of meloxicam in capsules with no evi- dence of interference from common excipients. The detection limit of this method was 25.6 ng/mL. The relative standard deviation was 2.1% for 10.0 μg/mL meloxicam. The sample throughput was found to be 120 samples/h.
基金Project (41171361) supported by the National Natural Science Foundation of China
文摘Substance flow analysis was applied to analyzing the lead emissions in 2010. It turns out that in 2010, for every 1 kg of lead consumed, 0.48 kg lead is lost into the environment. The emissions in 2010 were estimated to be 1.89×10^6 t, which were mainly from use （39.20%） and waste management＆recycling （33.13%）. The accumulative lead in 1960-2010 from the anthropogenic flow was estimated and the results show that the total accumulative lead in this period amounted to 19.54×10^6 t, which was equivalent to 14.26 kg and 2.04 g/m^2 at the present population and territory.
