Subtropical sediment cores (QA09-1 and QA12-9) from the coastal zone of Qi’ao Island in the Zhujiang River Estuary were used to determine the rates of sulfate reduction and their response to experimental tempera-tu...Subtropical sediment cores (QA09-1 and QA12-9) from the coastal zone of Qi’ao Island in the Zhujiang River Estuary were used to determine the rates of sulfate reduction and their response to experimental tempera-ture changes. The depth distribution of the sulfate reduction rates was measured from whole-core incu-bations with radioactive tracer35SO42-, and peaks of 181.19 nmol/(cm3·d) and 107.49 nmol/(cm3·d) were exhibited at stations QA09-1 and QA12-9, respectively. The profiles of the pore water methane and sulfate concentrations demonstrated that anaerobic oxidation of methane occurred in the study area, which result-ed in an increase in the sulfate reduction rate at the base of the sulfate-reducing zone. Meanwhile, the sulfate concentration was not a major limiting factor for controlling the rates of sulfate reduction. In addition, the incubation of the sediment slurries in a block with a temperature gradient showed that the optimum tem-perature for the sulfate reduction reaction was 36°C. The Arrhenius plot was linear from the lowest tempera-ture to the optimum temperature, and the activation energy was at the lower end of the range of previously reported values. The results suggested that the ambient temperature regime of marine environments prob-ably selected for the microbial population with the best-suited physiology for the respective environment.展开更多
Slickwater fracturing fluids are widely used in the development of unconventional oil and gas resources due to the advantages of low cost,low formation damage and high drag reduction performance.However,their performa...Slickwater fracturing fluids are widely used in the development of unconventional oil and gas resources due to the advantages of low cost,low formation damage and high drag reduction performance.However,their performance is severely affected at high temperatures.Drag reducing agent is the key to determine the drag reducing performance of slickwater.In this work,in order to further improve the temperature resistance of slickwater,a temperature-resistant polymeric drag reducing agent(PDRA)was synthesized and used as the basis for preparing the temperature-resistant slickwater.The slickwater system was prepared with the compositions of 0.2 wt%PDRA,0.05 wt%drainage aid nonylphenol polyoxyethylene ether phosphate(NPEP)and 0.5 wt%anti-expansion agent polyepichlorohydrindimethylamine(PDM).The drag reduction ability,rheology properties,temperature and shear resistance ability,and core damage property of slickwater were systematically studied and evaluated.In contrast to on-site drag reducing agent(DRA)and HPAM,the temperature-resistant slickwater demonstrates enhanced drag reduction efficacy at 90℃,exhibiting superior temperature and shear resistance ability.Notably,the drag reduction retention rate for the slickwater achieved an impressive 90.52%after a 30-min shearing period.Additionally,the core damage is only 5.53%.We expect that this study can broaden the application of slickwater in high-temperature reservoirs and provide a theoretical basis for field applications.展开更多
Investigation on Cr(Ⅵ) reduction was conducted using Pseudomonas aeruginosa. The study demonstrated that the Cr(Ⅵ) can be effectively reduced to Cr(Ⅲ) by Pseudomonas aeruginosa. The effects of the factors affecting...Investigation on Cr(Ⅵ) reduction was conducted using Pseudomonas aeruginosa. The study demonstrated that the Cr(Ⅵ) can be effectively reduced to Cr(Ⅲ) by Pseudomonas aeruginosa. The effects of the factors affecting Cr(Ⅵ) reduction rate including carbon source type, pH, initial Cr(Ⅵ) concentration and amount of cells inoculum were thoroughly studied. Malate was found to yield maximum biotransformation, followed by succinate and glucose, with the reduction rate of 60.86%, 43.76% and 28.86% respectively. The optimum pH for Cr(Ⅵ) reduction was 7.0, with reduction efficiency of 61.71% being achieved. With the increase of initial Cr(Ⅵ) concentration, the rate of Cr(Ⅵ) reduction decreased. The reduction was inhibited strongly when the initial Cr(Ⅵ) concentration increased to 157 mg/L. As the amount of cells inoculum increased, the rate of Cr(Ⅵ) reduction also increased. The mechanism of Cr(Ⅵ) reduction and final products were also analysed. The results suggested that the soluble enzymes appear to be responsible for Cr(Ⅵ) reduction by Pseudomonas aeruginosa, and the reduced Cr(Ⅲ) was not precipitated in the form of Cr(OH) 3.展开更多
The effect of metallurgical fluxes CaO and CaCO3 on the reduction rate of iron ore pellets containing carbon in nitrogen atmosphere has been studied by a weight-loss thermal balance. The experimental results showed th...The effect of metallurgical fluxes CaO and CaCO3 on the reduction rate of iron ore pellets containing carbon in nitrogen atmosphere has been studied by a weight-loss thermal balance. The experimental results showed that adding CaO or CaCO3 can promote reduction reaction as the added CaO or CaCO3 probably decrease the apparent activation energy of iron ore concentrate-carbon-CaO or CaCO3 reaction, and the reduction rate constant changes with mass percent of CaO and CaCO3. The kinetic analysis also showed that the rate-controlling step of the reaction is inner gas diffusion.展开更多
Based on molecular dynamics simulation results, a lauryl methacrylate polymer with drag reduction and shear resistance properties was designed, and synthesized by emulsion polymerization using 2-vinyl pyridine and met...Based on molecular dynamics simulation results, a lauryl methacrylate polymer with drag reduction and shear resistance properties was designed, and synthesized by emulsion polymerization using 2-vinyl pyridine and methyl methacrylate as the polar polymerization monomer. After ionization of lauryl methacrylate polymer, an ion-dipole interaction based drag reduction agent (DRA) was obtained. The existence of ion-dipole interaction was proven through characterization of the drag-reducing agent from its infrared (IR) spectrum. The pilot-scale reaction yield of the DRA under optimum conditions was investigated, and the drag reduction and shear resistance properties were measured. The results show that: l) The ion-dipole or hydrogen bonding interaction can form ladder-shaped chains, therefore the synthesized DRA has shear resistance properties; 2) The larger the molecular weight (MW) and more concentrated the distribution of MW, the better the drag reduction efficiency and the performance of the ionomer system was superior to that of the hydrogen bonding system; 3) With increasing shear frequency, the drag-reduction rates of both the DRAs decreased, and the drag reduction rate of the ionomer system decreased more slowly than of the corresponding hydrogen bonding system. From the point of view of drag reduction rate and shear resistance property, the ionomer system is more promising than the hydrogen bonding system展开更多
The main objective of this study is to numerically investigate the characteristics of ultimate compressive strength of stiffened panels with opening and also to fit the design-oriented formulae. For this purpose, thre...The main objective of this study is to numerically investigate the characteristics of ultimate compressive strength of stiffened panels with opening and also to fit the design-oriented formulae. For this purpose, three series of well executed experimental data on longitudinally stiffened steel plates with and without opening subjected to the uniform axial in-pane load which is carried out to study the buckling and post-buckling up to the final failure are chosen. Also, a nonlinear finite element method capable of efficiently analyzing the large elasto-plastic deflection behavior of stiffened panels is developed and used for simulation. The feasibility of the present simulation process is confirmed by a good agreement with the experimental results. More case studies are developed employing the simulation process to analyze the influence of various design variables on the reduction rate of ultimate strength of stiffened panel induced by opening. Based on the computed results, two design formulae are fitted and the accuracy of design formulae is studied. Furthermore, the viability of the design formulae for practical engineering is proved.展开更多
A high-temperature reduction and smelting process was used to recover iron and calcium aluminate slag from high-ferrous bauxite. The effects of w(CaO)/w(SiO_2) ratio, anthracite ratio, and reduction temperature an...A high-temperature reduction and smelting process was used to recover iron and calcium aluminate slag from high-ferrous bauxite. The effects of w(CaO)/w(SiO_2) ratio, anthracite ratio, and reduction temperature and time on the recovery and size of iron nuggets and on the Al_2O_3 grade of the calcium aluminate slag were investigated through thermodynamic calculations and experiments. The optimized process conditions were the bauxite/anthracite/slaked lime weight ratio of 100:16.17:59.37, reduction temperature of 1450°C and reduction time of 20 min. Under these conditions, high-quality iron nuggets and calcium aluminate slag were obtained. The largest size and the highest recovery rate of iron nuggets were 11.42 mm and 92.79wt%, respectively. The calcium aluminate slag mainly comprised Ca_2 SiO_4 and Ca_(12)Al_(14)O_(33), with small amounts of Fe Al_2O_4, CaAl_2O_4, and Ca_2Al_2SiO_7.展开更多
Reduction rate of ferrous oxide in smelting reduction with iron bath has been studied. The main affecting factors on reduction rate, such as composition of the melt, temperature of molten bath, basicity of slag...Reduction rate of ferrous oxide in smelting reduction with iron bath has been studied. The main affecting factors on reduction rate, such as composition of the melt, temperature of molten bath, basicity of slag and the way of supplying carbonaceous materials have also been investigated.展开更多
The reduction rate of Fe^tO in CaOSiO_2Al_2O_3Fe_tO slags with graphite powder has been determined in an alumina crucible at 1 673-1 823 K. The effects of temperature, slag basicity and Fe_tO content on the reduc...The reduction rate of Fe^tO in CaOSiO_2Al_2O_3Fe_tO slags with graphite powder has been determined in an alumina crucible at 1 673-1 823 K. The effects of temperature, slag basicity and Fe_tO content on the reduction rate have also been discussed. Test results show that the reduction rate increases with the increase of temperature or Fe_tO concentration in slags, and the reduction rate has a parabolic relation with slag simple basicity or optical basicity. The maximum reduction rate is observed around CaO/SiO_2=1.5 of molten slags. The reaction order is 1.26 or 1.31, and the reduction activation energy is 126.8 or 129.7 kJ/mol respectively in regard to Fe_tO content or Fe_tO activity calculated by using regular solution model. The reduction rate of Fe_tO in CaOSiO_2Al_2O_3Fe_tO slags with graphite powder is in the range of 0.15×10^-4-0.86×10^-4 molO/cm^2·s.展开更多
Bath smelting reduction for recovering zinc from EAF (Electric Arc Furnace) dust has been investigated in the laboratory. A degree of zinc volatilization of more than 99% was obtained from the process. Temperature has...Bath smelting reduction for recovering zinc from EAF (Electric Arc Furnace) dust has been investigated in the laboratory. A degree of zinc volatilization of more than 99% was obtained from the process. Temperature has a clear influence on the reduction rate of ZnO in slag. The reduction rate of (ZnO) by [C] is the first order with respect to the content of ZnO in the slag. The apparent activation energy of the (ZnO) reduction reaction is 312 kJ/mol at 1300-1500℃.展开更多
The past two decades witnessed a broad-increase in web technology and on-line gaming.Enhancing the broadband confinements is viewed as one of the most significant variables that prompted new gaming technology.The imme...The past two decades witnessed a broad-increase in web technology and on-line gaming.Enhancing the broadband confinements is viewed as one of the most significant variables that prompted new gaming technology.The immense utilization of web applications and games additionally prompted growth in the handled devices and moving the limited gaming experience from user devices to online cloud servers.As internet capabilities are enhanced new ways of gaming are being used to improve the gaming experience.In cloud-based video gaming,game engines are hosted in cloud gaming data centers,and compressed gaming scenes are rendered to the players over the internet with updated controls.In such systems,the task of transferring games and video compression imposes huge computational complexity is required on cloud servers.The basic problems in cloud gaming in particular are high encoding time,latency,and low frame rates which require a new methodology for a better solution.To improve the bandwidth issue in cloud games,the compression of video sequences requires an alternative mechanism to improve gaming adaption without input delay.In this paper,the proposed improved methodology is used for automatic unnecessary scene detection,scene removing and bit rate reduction using an adaptive algorithm for object detection in a game scene.As a result,simulations showed without much impact on the players’quality experience,the selective object encoding method and object adaption technique decrease the network latency issue,reduce the game streaming bitrate at a remarkable scale on different games.The proposed algorithm was evaluated for three video game scenes.In this paper,achieved 14.6%decrease in encoding and 45.6%decrease in bit rate for the first video game scene.展开更多
Using K2S2O8-Na2SO3 as the redox initiation system,a hydrogen-bond-association-based dodecyl methacrylate system associative anti-shear drag reducer was synthesised by standard emulsion polymerisation.The reaction pro...Using K2S2O8-Na2SO3 as the redox initiation system,a hydrogen-bond-association-based dodecyl methacrylate system associative anti-shear drag reducer was synthesised by standard emulsion polymerisation.The reaction process was simple and gentle as well as safe and stable.Molecular design was carried out using molecular dynamics simulation methods.The results of infrared spectroscopy,thermogravimetric analysis,differential scanning calorimetry,gel chromatography,and laser light scattering showed that the reaction polymerisation was relatively complete,the product was uniform,the molecular weight distribution was controllable,and the synthesised polymer had good flexibility.The donor lauryl methacrylate-styrene-methacrylic acid(LMA-St-MAA)and acceptor lauryl methacrylate-styrene-dimethylaminoethyl methacrylate(LMA-St-DMA)polymers had an associative intermolecular interaction force,which increased the molecular cluster size of the associative system complex.The complex had good shear resistance,and the test results of the tube pump shear test showed that the synthesised associative oil-soluble polymer drag reduction system exhibited better drag reduction rate performance than poly-α-olefins over repeated cycles.The research results provide a reference plan for minimising the number of station-to-station inputs,thereby ensuring the stability of oil pipelines and reducing transportation costs.展开更多
In order to improve the Power Quality(PQ)of traction power supply system and reduce the power rating and operation cost of compensator,a Static VAR Compensator(SVC)integrated Railway Power Conditioner(RPC)is presented...In order to improve the Power Quality(PQ)of traction power supply system and reduce the power rating and operation cost of compensator,a Static VAR Compensator(SVC)integrated Railway Power Conditioner(RPC)is presented in this paper.RPC is a widely used device in the AC electrified railway systems to enhance the PQ indices of the main network.The next generation of this equipment is Active Power Quality Compensator(APQC).The major concern of these compensators is their high kVA rating.In this paper,a hybrid technique is proposed to solve aforementioned problems.A combination of SVC as an auxiliary device is employed together with the main compensators,i.e.,RPC and APQC that leads on to the reduction of power rating of the main compensators.The use of proposed scheme will cause to reduce significantly the initial investment cost of compensation system.The main compensators are only utilized to balance active powers of two adjacent feeder sections and suppress harmonic currents.The SVCs are used to compensate reactive power and suppress the third and fifth harmonic currents.In this paper firstly,the PQ compensation procedure in AC electrified railway is analyzed step by step.Then,the control strategies for SVC and the main compensators are presented.Finally,a simulation is fulfilled using Matlab/Simulink software to verify the effectiveness and validity of the proposed scheme and compensation strategy and also demonstrate that this technique could compensate all PQ problems.展开更多
Coatings with six kinds of materials and different thickness were prepared by oxyacetylene flame spraying on carbon steel A3 substrates and then remelted by a new type of carbon arc remelting treatment(CRT)device.The ...Coatings with six kinds of materials and different thickness were prepared by oxyacetylene flame spraying on carbon steel A3 substrates and then remelted by a new type of carbon arc remelting treatment(CRT)device.The results indicated that all the deposited layers are homogeneous and compact.The CRT obviously increases the carbon content and the hardness of the deposited layers.展开更多
The purpose of this study is to investigate the control function and mechanisms of natural river notches. Physical and numerical experiments are analyzed in this study for two representative types of sediment events:...The purpose of this study is to investigate the control function and mechanisms of natural river notches. Physical and numerical experiments are analyzed in this study for two representative types of sediment events: high intensity and short duration Type A sediment disaster events, and low intensity and long duration Type B moderate non-disaster events. Two dimensionless parameters, sediment trapping rate and reduction rate of peak sediment transport, are defined to evaluate the sediment control function of river notches. Study results indicate that the contraction ratio of the notch has a significant influence on sediment control function, with high contraction ratios resulting in both high sediment-trapping and high reduction rates. River notches provide better sediment control during Type A events than Type B events. The sediment control mechanism of river notches is the result of multiple interactions among river flow, sediment transport, and riverbed variation. Analysis of these interactions supports the significant protection role of river notches on sediment control for disaster events.展开更多
In order to make Mucuna seeds consumable, seeds are treated according to the following procedures: boiling, soaking followed by boiling in the presence of 0.5% KOH and finally soaking for a long time followed by boili...In order to make Mucuna seeds consumable, seeds are treated according to the following procedures: boiling, soaking followed by boiling in the presence of 0.5% KOH and finally soaking for a long time followed by boiling in the presence of 0.5% KOH, so that tannins can be removed. Preliminary studies done on the raw seeds of four Mucuna species revealed the presence of tannins. The results showed that the crushed seeds contained all high tannin with the content of 0.370 g GAE/100g DM, 0.336 g GAE/100g DM;0.266 g GAE/100g DM and 0.203 g GAE/100g DM for Mucuna deerigiana, Mucuna nagaland, Mucuna cochinchinensis and Mucuna rajada respectively. The different methods of seed treatment significantly reduced the tannin content in Mucuna seeds. The method of soaking the seeds for 12 hours and then scalding in the presence of 0.5% KOH reduced tannins in Mucuna deerigiana, Mucuna nagaland, Mucuna cochinchinensis, and Mucuna rajada seeds by 47.29%;48.21%;66.16%;and 15.76% respectively. This method gave the highest tannin reduction rate.展开更多
In oilfield fracturing construction, to solve the technical problems such as poor dissolution effect and long dissolution time of polymer drag reducer powder, the rheological regulator, phase transfer agent, organic s...In oilfield fracturing construction, to solve the technical problems such as poor dissolution effect and long dissolution time of polymer drag reducer powder, the rheological regulator, phase transfer agent, organic solvent, and drag reducer powder were compounded to prepare a drag reducer emulsion that was soluble in water. The stability of the drag reducer emulsion was observed at room temperature for 90 days. The effects of the rheological regulator, phase transfer agent, and organic solvent on the stability and solubility of the drag reducer emulsion were studied. The dissolution time, dissolution effect, viscosity of the aqueous solution, and drag reduction performance of the drag reducer emulsion were evaluated. The results show the stability rate of the drag reducer emulsion prepared by MOST-1 rheological regulator, BHJ-8 and BHJ-6 compound phase inversion agent, ethylene glycol ether and 120 - 140 mesh powder can reach 97% at room temperature for 90 days. Compared with the drag reducer powder, when the aqueous solution concentration is 0.1%, the dissolution time is only 28 s, the viscosity can be increased by 30%, and the drag reduction rate can be increased by up to 8%.展开更多
We have designed a breathing paced television;a television that plays content in sync with users’ activity of exhaling through pursed lips, to achieve better motivation and compliance of such exercises. Described sys...We have designed a breathing paced television;a television that plays content in sync with users’ activity of exhaling through pursed lips, to achieve better motivation and compliance of such exercises. Described system has been tested with control group who have watched the same video. Breathing rate reduction was significantly higher in active group (54.48% ± 8.34%) than in control group (6.84% ± 17.21%), however, the proposed method of watching television is obviously not as trivial as watching television per se.展开更多
High-chromium vanadium-titanium magnetite(HCVTM)is a valuable resource containing metal elements such as iron,vanadium,titanium,and chromium.To recycle these elements,direct reduction is an efficient way.The mechanism...High-chromium vanadium-titanium magnetite(HCVTM)is a valuable resource containing metal elements such as iron,vanadium,titanium,and chromium.To recycle these elements,direct reduction is an efficient way.The mechanism and reaction kinetic parameters for the direct reduction of HCVTM were studied.Experimental results show that the reduction degree increases obviously when the C/O ratio and temperature increase.Thermodynamic analysis showed a dramatic mass loss in the direct reduction of HCVTM in the temperature range of 985-1160℃.From 1200 to 1350℃,the reduction curves for the isothermal reduction of HCVTM followed the same trend,with a sharp increase in the initial reaction zone and a slight increase in the reduction rate with increasing time,and finally,the isothermal reduction process of HCVTM was divided into several limiting stages with varying degrees,with inconsistent limiting factors for the reaction rate at different stages.The results also show that the activation energy decreases slightly at larger degrees of reduction.Also,the apparent rate constant k(T)increased with increasing reduction temperature,with lnk(T)showing a good linear relationship with temperature.展开更多
The use of low-grade,refractory and composite paragenetic mineral resources is necessary for overcoming the shortage of iron ore resources in China.As a solution to the treatment of such iron ores,the direct reduction...The use of low-grade,refractory and composite paragenetic mineral resources is necessary for overcoming the shortage of iron ore resources in China.As a solution to the treatment of such iron ores,the direct reduction of carbon-bearing pellets can ensure complete iron removal and the effective enrichment of other high-value elements.Thus,this technology enjoys a broad application prospect.However,there are several problems with low-temperature reduction,such as low iron ore reaction efficiency,long reaction time,and high energy consumption.To improve the low-temperature carbothermic reduction efficiency of iron ores,a static magnetic field with magnetic induction intensity of 1.0 T was introduced.An isothermal reduction experiment was conducted at 1223 K to study the low-temperature self-reduction characteristics of carbon-bearing pellets of Bayan Obo lean iron ores in the static magnetic field.Also,the acting mechanism of the magnetic field was explored from the perspective of the reduction process,reaction efficiency,phase composition,microstructure changes,and dynamic behavior of iron ores.The results showed that the magnetic field can increase the low-temperature reduction rate of carbon-bearing pellets of Bayan Obo lean iron ores.Under the conditions of reduction temperature of 1223 K,magnetic induction intensity of 1.0 T,and reduction time of 60 min,the reduction degree was 92.42%,1.65 times that without a magnetic field.The magnetic field promoted the replacement of Ca^(2+)and Fe^(2+),so that the hard-to-reduce iron-bearing silicates were reduced in the order of Fe2SiO_(4)→(Ca,Na)FeSiO_(4)→FeO→Fe.The magnetic field enabled loose minerals,more pores and cracks,and changes in the growth morphology and distribution position of metallic iron.Compared with the case under the non-magnetic condition,the metallic iron precipitated from the slag phase in a foliated shape,separated from the matrix iron oxides,and grew up at the junction of the slag phase and coke.The magnetic field significantly increased the interfacial chemical reaction rate of the carbothermic reduction of iron ores and reduced the internal diffusion resistance of gas in the product layer.Specifically,the interfacial chemical reaction rate increased by 138%and the internal diffusion coefficient increased by 309%.Therefore,the effect of the magnetic field on the internal diffusion resistance was the main cause for strengthening the low-temperature reduction of iron ores.展开更多
基金The National Natural Science Foundation of China under contract Nos 40803020 and 41176065
文摘Subtropical sediment cores (QA09-1 and QA12-9) from the coastal zone of Qi’ao Island in the Zhujiang River Estuary were used to determine the rates of sulfate reduction and their response to experimental tempera-ture changes. The depth distribution of the sulfate reduction rates was measured from whole-core incu-bations with radioactive tracer35SO42-, and peaks of 181.19 nmol/(cm3·d) and 107.49 nmol/(cm3·d) were exhibited at stations QA09-1 and QA12-9, respectively. The profiles of the pore water methane and sulfate concentrations demonstrated that anaerobic oxidation of methane occurred in the study area, which result-ed in an increase in the sulfate reduction rate at the base of the sulfate-reducing zone. Meanwhile, the sulfate concentration was not a major limiting factor for controlling the rates of sulfate reduction. In addition, the incubation of the sediment slurries in a block with a temperature gradient showed that the optimum tem-perature for the sulfate reduction reaction was 36°C. The Arrhenius plot was linear from the lowest tempera-ture to the optimum temperature, and the activation energy was at the lower end of the range of previously reported values. The results suggested that the ambient temperature regime of marine environments prob-ably selected for the microbial population with the best-suited physiology for the respective environment.
基金supported by the National Natural Science Foundation of China(Nos.52222403,52074333,52120105007)Taishan Scholar Young Expert(No.tsqn202211079)。
文摘Slickwater fracturing fluids are widely used in the development of unconventional oil and gas resources due to the advantages of low cost,low formation damage and high drag reduction performance.However,their performance is severely affected at high temperatures.Drag reducing agent is the key to determine the drag reducing performance of slickwater.In this work,in order to further improve the temperature resistance of slickwater,a temperature-resistant polymeric drag reducing agent(PDRA)was synthesized and used as the basis for preparing the temperature-resistant slickwater.The slickwater system was prepared with the compositions of 0.2 wt%PDRA,0.05 wt%drainage aid nonylphenol polyoxyethylene ether phosphate(NPEP)and 0.5 wt%anti-expansion agent polyepichlorohydrindimethylamine(PDM).The drag reduction ability,rheology properties,temperature and shear resistance ability,and core damage property of slickwater were systematically studied and evaluated.In contrast to on-site drag reducing agent(DRA)and HPAM,the temperature-resistant slickwater demonstrates enhanced drag reduction efficacy at 90℃,exhibiting superior temperature and shear resistance ability.Notably,the drag reduction retention rate for the slickwater achieved an impressive 90.52%after a 30-min shearing period.Additionally,the core damage is only 5.53%.We expect that this study can broaden the application of slickwater in high-temperature reservoirs and provide a theoretical basis for field applications.
文摘Investigation on Cr(Ⅵ) reduction was conducted using Pseudomonas aeruginosa. The study demonstrated that the Cr(Ⅵ) can be effectively reduced to Cr(Ⅲ) by Pseudomonas aeruginosa. The effects of the factors affecting Cr(Ⅵ) reduction rate including carbon source type, pH, initial Cr(Ⅵ) concentration and amount of cells inoculum were thoroughly studied. Malate was found to yield maximum biotransformation, followed by succinate and glucose, with the reduction rate of 60.86%, 43.76% and 28.86% respectively. The optimum pH for Cr(Ⅵ) reduction was 7.0, with reduction efficiency of 61.71% being achieved. With the increase of initial Cr(Ⅵ) concentration, the rate of Cr(Ⅵ) reduction decreased. The reduction was inhibited strongly when the initial Cr(Ⅵ) concentration increased to 157 mg/L. As the amount of cells inoculum increased, the rate of Cr(Ⅵ) reduction also increased. The mechanism of Cr(Ⅵ) reduction and final products were also analysed. The results suggested that the soluble enzymes appear to be responsible for Cr(Ⅵ) reduction by Pseudomonas aeruginosa, and the reduced Cr(Ⅲ) was not precipitated in the form of Cr(OH) 3.
文摘The effect of metallurgical fluxes CaO and CaCO3 on the reduction rate of iron ore pellets containing carbon in nitrogen atmosphere has been studied by a weight-loss thermal balance. The experimental results showed that adding CaO or CaCO3 can promote reduction reaction as the added CaO or CaCO3 probably decrease the apparent activation energy of iron ore concentrate-carbon-CaO or CaCO3 reaction, and the reduction rate constant changes with mass percent of CaO and CaCO3. The kinetic analysis also showed that the rate-controlling step of the reaction is inner gas diffusion.
基金supported by the Basic Research Program of China(973Program,Grant No.2008CB617508)
文摘Based on molecular dynamics simulation results, a lauryl methacrylate polymer with drag reduction and shear resistance properties was designed, and synthesized by emulsion polymerization using 2-vinyl pyridine and methyl methacrylate as the polar polymerization monomer. After ionization of lauryl methacrylate polymer, an ion-dipole interaction based drag reduction agent (DRA) was obtained. The existence of ion-dipole interaction was proven through characterization of the drag-reducing agent from its infrared (IR) spectrum. The pilot-scale reaction yield of the DRA under optimum conditions was investigated, and the drag reduction and shear resistance properties were measured. The results show that: l) The ion-dipole or hydrogen bonding interaction can form ladder-shaped chains, therefore the synthesized DRA has shear resistance properties; 2) The larger the molecular weight (MW) and more concentrated the distribution of MW, the better the drag reduction efficiency and the performance of the ionomer system was superior to that of the hydrogen bonding system; 3) With increasing shear frequency, the drag-reduction rates of both the DRAs decreased, and the drag reduction rate of the ionomer system decreased more slowly than of the corresponding hydrogen bonding system. From the point of view of drag reduction rate and shear resistance property, the ionomer system is more promising than the hydrogen bonding system
基金financially supported by Mid-Career Researcher Program NRF(Grant No.NRF-2013R1A2A2A01017021)funded by the Ministry of ScienceICT and Future Planning of Korea,and HIT Discipline Guide Fund(Grant No.WH20140102)
文摘The main objective of this study is to numerically investigate the characteristics of ultimate compressive strength of stiffened panels with opening and also to fit the design-oriented formulae. For this purpose, three series of well executed experimental data on longitudinally stiffened steel plates with and without opening subjected to the uniform axial in-pane load which is carried out to study the buckling and post-buckling up to the final failure are chosen. Also, a nonlinear finite element method capable of efficiently analyzing the large elasto-plastic deflection behavior of stiffened panels is developed and used for simulation. The feasibility of the present simulation process is confirmed by a good agreement with the experimental results. More case studies are developed employing the simulation process to analyze the influence of various design variables on the reduction rate of ultimate strength of stiffened panel induced by opening. Based on the computed results, two design formulae are fitted and the accuracy of design formulae is studied. Furthermore, the viability of the design formulae for practical engineering is proved.
基金financially supported by the International Scientific and Technological Cooperation and Exchange Projects of China (No. 2013DFG50640)
文摘A high-temperature reduction and smelting process was used to recover iron and calcium aluminate slag from high-ferrous bauxite. The effects of w(CaO)/w(SiO_2) ratio, anthracite ratio, and reduction temperature and time on the recovery and size of iron nuggets and on the Al_2O_3 grade of the calcium aluminate slag were investigated through thermodynamic calculations and experiments. The optimized process conditions were the bauxite/anthracite/slaked lime weight ratio of 100:16.17:59.37, reduction temperature of 1450°C and reduction time of 20 min. Under these conditions, high-quality iron nuggets and calcium aluminate slag were obtained. The largest size and the highest recovery rate of iron nuggets were 11.42 mm and 92.79wt%, respectively. The calcium aluminate slag mainly comprised Ca_2 SiO_4 and Ca_(12)Al_(14)O_(33), with small amounts of Fe Al_2O_4, CaAl_2O_4, and Ca_2Al_2SiO_7.
文摘Reduction rate of ferrous oxide in smelting reduction with iron bath has been studied. The main affecting factors on reduction rate, such as composition of the melt, temperature of molten bath, basicity of slag and the way of supplying carbonaceous materials have also been investigated.
文摘The reduction rate of Fe^tO in CaOSiO_2Al_2O_3Fe_tO slags with graphite powder has been determined in an alumina crucible at 1 673-1 823 K. The effects of temperature, slag basicity and Fe_tO content on the reduction rate have also been discussed. Test results show that the reduction rate increases with the increase of temperature or Fe_tO concentration in slags, and the reduction rate has a parabolic relation with slag simple basicity or optical basicity. The maximum reduction rate is observed around CaO/SiO_2=1.5 of molten slags. The reaction order is 1.26 or 1.31, and the reduction activation energy is 126.8 or 129.7 kJ/mol respectively in regard to Fe_tO content or Fe_tO activity calculated by using regular solution model. The reduction rate of Fe_tO in CaOSiO_2Al_2O_3Fe_tO slags with graphite powder is in the range of 0.15×10^-4-0.86×10^-4 molO/cm^2·s.
文摘Bath smelting reduction for recovering zinc from EAF (Electric Arc Furnace) dust has been investigated in the laboratory. A degree of zinc volatilization of more than 99% was obtained from the process. Temperature has a clear influence on the reduction rate of ZnO in slag. The reduction rate of (ZnO) by [C] is the first order with respect to the content of ZnO in the slag. The apparent activation energy of the (ZnO) reduction reaction is 312 kJ/mol at 1300-1500℃.
文摘The past two decades witnessed a broad-increase in web technology and on-line gaming.Enhancing the broadband confinements is viewed as one of the most significant variables that prompted new gaming technology.The immense utilization of web applications and games additionally prompted growth in the handled devices and moving the limited gaming experience from user devices to online cloud servers.As internet capabilities are enhanced new ways of gaming are being used to improve the gaming experience.In cloud-based video gaming,game engines are hosted in cloud gaming data centers,and compressed gaming scenes are rendered to the players over the internet with updated controls.In such systems,the task of transferring games and video compression imposes huge computational complexity is required on cloud servers.The basic problems in cloud gaming in particular are high encoding time,latency,and low frame rates which require a new methodology for a better solution.To improve the bandwidth issue in cloud games,the compression of video sequences requires an alternative mechanism to improve gaming adaption without input delay.In this paper,the proposed improved methodology is used for automatic unnecessary scene detection,scene removing and bit rate reduction using an adaptive algorithm for object detection in a game scene.As a result,simulations showed without much impact on the players’quality experience,the selective object encoding method and object adaption technique decrease the network latency issue,reduce the game streaming bitrate at a remarkable scale on different games.The proposed algorithm was evaluated for three video game scenes.In this paper,achieved 14.6%decrease in encoding and 45.6%decrease in bit rate for the first video game scene.
基金scientific research project of SINOPEC Corporation(CLY19005)2020 Key R&D Program of Shandong Province(2020CXGC010403).
文摘Using K2S2O8-Na2SO3 as the redox initiation system,a hydrogen-bond-association-based dodecyl methacrylate system associative anti-shear drag reducer was synthesised by standard emulsion polymerisation.The reaction process was simple and gentle as well as safe and stable.Molecular design was carried out using molecular dynamics simulation methods.The results of infrared spectroscopy,thermogravimetric analysis,differential scanning calorimetry,gel chromatography,and laser light scattering showed that the reaction polymerisation was relatively complete,the product was uniform,the molecular weight distribution was controllable,and the synthesised polymer had good flexibility.The donor lauryl methacrylate-styrene-methacrylic acid(LMA-St-MAA)and acceptor lauryl methacrylate-styrene-dimethylaminoethyl methacrylate(LMA-St-DMA)polymers had an associative intermolecular interaction force,which increased the molecular cluster size of the associative system complex.The complex had good shear resistance,and the test results of the tube pump shear test showed that the synthesised associative oil-soluble polymer drag reduction system exhibited better drag reduction rate performance than poly-α-olefins over repeated cycles.The research results provide a reference plan for minimising the number of station-to-station inputs,thereby ensuring the stability of oil pipelines and reducing transportation costs.
文摘In order to improve the Power Quality(PQ)of traction power supply system and reduce the power rating and operation cost of compensator,a Static VAR Compensator(SVC)integrated Railway Power Conditioner(RPC)is presented in this paper.RPC is a widely used device in the AC electrified railway systems to enhance the PQ indices of the main network.The next generation of this equipment is Active Power Quality Compensator(APQC).The major concern of these compensators is their high kVA rating.In this paper,a hybrid technique is proposed to solve aforementioned problems.A combination of SVC as an auxiliary device is employed together with the main compensators,i.e.,RPC and APQC that leads on to the reduction of power rating of the main compensators.The use of proposed scheme will cause to reduce significantly the initial investment cost of compensation system.The main compensators are only utilized to balance active powers of two adjacent feeder sections and suppress harmonic currents.The SVCs are used to compensate reactive power and suppress the third and fifth harmonic currents.In this paper firstly,the PQ compensation procedure in AC electrified railway is analyzed step by step.Then,the control strategies for SVC and the main compensators are presented.Finally,a simulation is fulfilled using Matlab/Simulink software to verify the effectiveness and validity of the proposed scheme and compensation strategy and also demonstrate that this technique could compensate all PQ problems.
文摘Coatings with six kinds of materials and different thickness were prepared by oxyacetylene flame spraying on carbon steel A3 substrates and then remelted by a new type of carbon arc remelting treatment(CRT)device.The results indicated that all the deposited layers are homogeneous and compact.The CRT obviously increases the carbon content and the hardness of the deposited layers.
基金financial support were provided by the Disaster Prevention Research Center, National Cheng Kung University
文摘The purpose of this study is to investigate the control function and mechanisms of natural river notches. Physical and numerical experiments are analyzed in this study for two representative types of sediment events: high intensity and short duration Type A sediment disaster events, and low intensity and long duration Type B moderate non-disaster events. Two dimensionless parameters, sediment trapping rate and reduction rate of peak sediment transport, are defined to evaluate the sediment control function of river notches. Study results indicate that the contraction ratio of the notch has a significant influence on sediment control function, with high contraction ratios resulting in both high sediment-trapping and high reduction rates. River notches provide better sediment control during Type A events than Type B events. The sediment control mechanism of river notches is the result of multiple interactions among river flow, sediment transport, and riverbed variation. Analysis of these interactions supports the significant protection role of river notches on sediment control for disaster events.
文摘In order to make Mucuna seeds consumable, seeds are treated according to the following procedures: boiling, soaking followed by boiling in the presence of 0.5% KOH and finally soaking for a long time followed by boiling in the presence of 0.5% KOH, so that tannins can be removed. Preliminary studies done on the raw seeds of four Mucuna species revealed the presence of tannins. The results showed that the crushed seeds contained all high tannin with the content of 0.370 g GAE/100g DM, 0.336 g GAE/100g DM;0.266 g GAE/100g DM and 0.203 g GAE/100g DM for Mucuna deerigiana, Mucuna nagaland, Mucuna cochinchinensis and Mucuna rajada respectively. The different methods of seed treatment significantly reduced the tannin content in Mucuna seeds. The method of soaking the seeds for 12 hours and then scalding in the presence of 0.5% KOH reduced tannins in Mucuna deerigiana, Mucuna nagaland, Mucuna cochinchinensis, and Mucuna rajada seeds by 47.29%;48.21%;66.16%;and 15.76% respectively. This method gave the highest tannin reduction rate.
文摘In oilfield fracturing construction, to solve the technical problems such as poor dissolution effect and long dissolution time of polymer drag reducer powder, the rheological regulator, phase transfer agent, organic solvent, and drag reducer powder were compounded to prepare a drag reducer emulsion that was soluble in water. The stability of the drag reducer emulsion was observed at room temperature for 90 days. The effects of the rheological regulator, phase transfer agent, and organic solvent on the stability and solubility of the drag reducer emulsion were studied. The dissolution time, dissolution effect, viscosity of the aqueous solution, and drag reduction performance of the drag reducer emulsion were evaluated. The results show the stability rate of the drag reducer emulsion prepared by MOST-1 rheological regulator, BHJ-8 and BHJ-6 compound phase inversion agent, ethylene glycol ether and 120 - 140 mesh powder can reach 97% at room temperature for 90 days. Compared with the drag reducer powder, when the aqueous solution concentration is 0.1%, the dissolution time is only 28 s, the viscosity can be increased by 30%, and the drag reduction rate can be increased by up to 8%.
文摘We have designed a breathing paced television;a television that plays content in sync with users’ activity of exhaling through pursed lips, to achieve better motivation and compliance of such exercises. Described system has been tested with control group who have watched the same video. Breathing rate reduction was significantly higher in active group (54.48% ± 8.34%) than in control group (6.84% ± 17.21%), however, the proposed method of watching television is obviously not as trivial as watching television per se.
基金the support from the National Natural Science Foundation of China(Nos.52074081 and 52174319)the National Key Research and Development Plan(No.2021YFC290IOOO).
文摘High-chromium vanadium-titanium magnetite(HCVTM)is a valuable resource containing metal elements such as iron,vanadium,titanium,and chromium.To recycle these elements,direct reduction is an efficient way.The mechanism and reaction kinetic parameters for the direct reduction of HCVTM were studied.Experimental results show that the reduction degree increases obviously when the C/O ratio and temperature increase.Thermodynamic analysis showed a dramatic mass loss in the direct reduction of HCVTM in the temperature range of 985-1160℃.From 1200 to 1350℃,the reduction curves for the isothermal reduction of HCVTM followed the same trend,with a sharp increase in the initial reaction zone and a slight increase in the reduction rate with increasing time,and finally,the isothermal reduction process of HCVTM was divided into several limiting stages with varying degrees,with inconsistent limiting factors for the reaction rate at different stages.The results also show that the activation energy decreases slightly at larger degrees of reduction.Also,the apparent rate constant k(T)increased with increasing reduction temperature,with lnk(T)showing a good linear relationship with temperature.
基金The authors are grateful for the financial support from the Natural Science Foundation of Inner Mongolia(2019MS05010)the National Natural Science Foundation of China(51464039 and 52064044).
文摘The use of low-grade,refractory and composite paragenetic mineral resources is necessary for overcoming the shortage of iron ore resources in China.As a solution to the treatment of such iron ores,the direct reduction of carbon-bearing pellets can ensure complete iron removal and the effective enrichment of other high-value elements.Thus,this technology enjoys a broad application prospect.However,there are several problems with low-temperature reduction,such as low iron ore reaction efficiency,long reaction time,and high energy consumption.To improve the low-temperature carbothermic reduction efficiency of iron ores,a static magnetic field with magnetic induction intensity of 1.0 T was introduced.An isothermal reduction experiment was conducted at 1223 K to study the low-temperature self-reduction characteristics of carbon-bearing pellets of Bayan Obo lean iron ores in the static magnetic field.Also,the acting mechanism of the magnetic field was explored from the perspective of the reduction process,reaction efficiency,phase composition,microstructure changes,and dynamic behavior of iron ores.The results showed that the magnetic field can increase the low-temperature reduction rate of carbon-bearing pellets of Bayan Obo lean iron ores.Under the conditions of reduction temperature of 1223 K,magnetic induction intensity of 1.0 T,and reduction time of 60 min,the reduction degree was 92.42%,1.65 times that without a magnetic field.The magnetic field promoted the replacement of Ca^(2+)and Fe^(2+),so that the hard-to-reduce iron-bearing silicates were reduced in the order of Fe2SiO_(4)→(Ca,Na)FeSiO_(4)→FeO→Fe.The magnetic field enabled loose minerals,more pores and cracks,and changes in the growth morphology and distribution position of metallic iron.Compared with the case under the non-magnetic condition,the metallic iron precipitated from the slag phase in a foliated shape,separated from the matrix iron oxides,and grew up at the junction of the slag phase and coke.The magnetic field significantly increased the interfacial chemical reaction rate of the carbothermic reduction of iron ores and reduced the internal diffusion resistance of gas in the product layer.Specifically,the interfacial chemical reaction rate increased by 138%and the internal diffusion coefficient increased by 309%.Therefore,the effect of the magnetic field on the internal diffusion resistance was the main cause for strengthening the low-temperature reduction of iron ores.