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

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

Rates of bacterial sulfate reduction and their response to experimental temperature changes in coastal sediments of Qi'ao Island, Zhujiang River Estuary in China

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.

Effect of CaO and CaCO3 on Reduction Rate of Iron Ore Pellets Containing Carbon

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.

Formulation of Reduction Rate for Ultimate Compressive Strength of Stiffened Panel Induced by Opening

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.

Reduction Rate of Ferrous Oxide in Smelting Reduction

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.

EFFECTS OF RATE OF ADDITION AND TENIPERATURE ON THE ENANTIOSELECTIVITY IN BORANE REDUCTION OF KETONES CATALYZED BY CHIRAL OXAZABOROLIDINE

The exoellent enantioselectivity with o. p. >99% in asymmetrio borane reduction of acetophenone catalyzed by (4S, 5R ) 4, 5-diphenyi-1. 3. 2-oxazaborolidine has been achieved via the important modincation of the reaction conditions.

Efficient Solvent- and Catalyst-Free Syntheses of Imine Derivatives Applying the Pressure Reduction Technique: Remarkable Change of the Reaction Rate with the Phase Transition

Because imines could be used as convenient starting materials in various fields, the development of an easy synthetic method of imine was strongly desired. In response to this demand, we thought that it would be an effective synthesis method if an aldehyde and an amine could be reacted to give an imine in good yield under solvent- and catalyst-free conditions. In fact, we tried the reaction of benzaldehyde with various amines under solvent- and catalyst-free conditions followed by removal of water that was produced in the reaction system by a vacuum pump, and desired imines could be obtained in good yields. Observation of this reaction using a nuclear magnetic resonance spectrometer revealed that the reaction rate was extremely fast at the initial stage but slowed over time. However, the reaction of benzaldehyde with aniline differed greatly, and the reaction rate dramatically improved in 47 - 48 minutes after the start of the reaction. At this time, we found that the reaction system underwent a phase transition from the liquid phase to the solid phase.

Bit Rate Reduction in Cloud Gaming Using Object Detection Technique

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.

Preparation of V-Ti-Fe master alloys by metallothermic reduction method

V-Ti-Fe master alloys were prepared by metaUothermic reduction method, and the influences of the mass ratio of V205 to TiO2, Al and Al-Mg alloy addition amounts on the metal recovery rates and alloy compositions were investigated. The results show that appropriate technological parameters are： the mass ratio of V205 to TiO2 is 0.5：1, Al addition represents 95% of the theoretical value, and the Al-Mg alloy addition amount is one third that of the Al addition. The results from energy spectrum analysis show that V and Fe distribute uniformly in the prepared alloy, while the segregation for Ti, i.e. Ti-rich phase is detected. A spray refming process was carried out to reduce the impurity contents of Al and O in the prepared alloys. The Al content drops from 4.27% to 1.86%, and the O content drops from 2.10% to 0.91% after the refining process.

Kinetics Study on O2 Adsorption and OHad Desorption at Pt（111）, Its Implication to Oxygen Reduction Reaction Kinetics

Kinetics of dissociative O2 adsorption, OHad desorption, and oxygen reduction reaction （ORR） at Pt（111） electrode in 0.1 mol/L HClO4 has been investigated. Reversible OHad adsorption/desorption occurs at potentials from 0.6 V to 1.0 V （vs. RHE） with the exchange current density of ca. 50 mA/cm^2 at 0.8 V, the fast kinetics of OHad desorption indicates that it should not be the rate determining step for ORR. In the kineticor kinetic-mass transport mix controlled potential region, ORR current at constant potential displays slight decrease with reaction time. ORR current in the positive-going potential scan is slightly larger than that in the subsequent negative-going scan with electrode rotation speed （〉800 r/min） and slow potential scan rate （〈100 mV/s）. The open circuit potential of Pt/0.1 mol/L HClO4 interface increases promptly from 0.9 V to 1.0 V after switch from O2 free- to O2-saturated solution. The increase of open circuit potential as well as ORR current decays under potential control due to the accumulation of OHad from dissociative adsorption of O2. It indicates that at Pt（111） the net rate for O2 decomposition to OHad is slightly faster than that for OHad removal, one cannot simply use the assumption of rate determining step to discuss ORR kinetics. Instead, the ORR kinetics is determined by both the kinetics for O2 decomposition to OHad as well as the thermo-equilibrium of OHad＋H^＋＋e→←H2O.

Experimental study on Cr(Ⅵ) reduction by Pseudomonas aeruginosa

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.

Soil respiration response to precipitation reduction in a grassland and a Mongolian pine plantation in semi-arid northeast China

Climate change is predicted to alter global precipitation regimes.However,the response of soil carbon and nitrogen cycles and soil microorganisms to precipitation reduction is poorly understood but is dependent on ecosystem type.To evaluate the impacts of reduced precipitation on soil respiration,soil inorganic nitrogen(i.e.,NH4^+–N and NO3^-–N),nitrogen mineralization,and soil microbial community composition,a precipitation manipulation experiment was initiated in a Mongolian pine plantation and a naturally restored grassland in semi-arid northeast China.Precipitation reduction led to decreases of soil respiration rates by 14 and 8%in 2014 and 2015 in the Mongolian pine plantation but no changes in the grassland.Soil inorganic nitrogen,ammonification and nitrification rate,and soil phospholipids fatty acids were not significantly changed by reduced precipitation but significantly differed between the two ecosystems and among growing seasons.Our results suggest that the impacts of precipitation reduction on soil respiration were different between the Mongolian pine plantation and the grassland,and that ecosystem type and growing season had more pronounced impacts on soil carbon and nitrogen cycles.

Drag reduction and shear resistance properties of ionomer and hydrogen bond systems based on lauryl methacrylate

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

Gas-phase electrocatalytic reduction of carbon dioxide using electrolytic cell based on phosphoric acid-doped polybenzimidazole membrane

Carbon dioxide transformation to fuels or chemicals provides an attractive approach for its utilization as feedstock and its emission reduction. Herein, we report a gas-phase electrocatalytic reduction of CO2 in an electrolytic cell, constructed using phosphoric acid-doped polybenz- imidazole （PBI） membrane, which allowed operation at 170 ℃ Pt/C and PtMo/C with variable ratio of Pt/Mo were studied as the cathode catalysts. The results showed that PtMo/C catalysts significantly enhanced CO formation and inhibited CH4 formation compared with Pt/C catalyst. Characterization by X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy revealed that most Mo species existed as MoO3 in PtMo/C catalysts and the interaction between Pt and MoOx was likely responsible for the enhanced CO formation rate although these bicomponent catalysts in general had a larger particle size than Pt/C catalyst.

Recovery of iron and calcium aluminate slag from high-ferrous bauxite by high-temperature reduction and smelting process

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.

CHARACTERISTICS OF THE OXYGEN REDUCTIONIN ATMOSPHERIC CORROSION

In this work on marine atmospheric corrosion the changes in oxygen reduction rate with decrease of electrolyte film thickness during drying was studied by Kelvin probe reference electrode technique andimpedance measurements based on previous results. For > 50μm electrolyte film thickness, the oxygen diffusion in liquid controlled the oxygen reduction process.As the cathodic limiting currents increased to about lmA/cm2 with evaporation, the rate of oxygen transportation at the gas/liquid boundary limited thecurrent increase. If the thickness decreased to less than 10μm, the very heterogeneous current distributioncaused a sharp decrease in the total cathodic current due to the effect of the electrolyte film’s increased solution resistance. The calculated result on the basis of the assumption showed good agreement with the experimental findings.

Application of Different Models for the Prediction of the Kinetics of Direct Reduction of Natural Iron Ores

Simulation of the direct reduction conditions was performed in a laboratory furnace. Lump samples from natural hematite iron ore were reduced by a gas mixture of H2 and CO (H2/CO =1.5) at temperatures of 700°C, 800°C and 900°C. The effect of reduction temperature on the reduction degree, reduction rate of samples and carbon deposition were investigated and discussed in this study. The thermo-gravimetric data obtained from the reduction experiments was run in a programme that calculates the solid conversion rate. Also, three models: 1) Grain Model (GM), 2) Volumetric Model (VM), and 3) the Random Pore Model (RPM), were used to estimate the reduction kinetics of natural iron ores. It was found that the RPM model result agreed best with the obtained experimental results. Furthermore, it gave better predictions of the natural iron oxide conversion and thereby the reduction kinetics.

Numerical simulation of chemical vapor deposition reaction in polysilicon reduction furnace

Three-dimensional model of chemical vapor deposition reaction in polysilicon reduction furnace was established by considering mass, momentum and energy transfer simultaneously. Then, CFD software was used to simulate the flow, heat transfer and chemical reaction process in reduction furnace and to analyze the change law of deposition characteristic along with the H_2 mole fraction, silicon rod height and silicon rod diameter. The results show that with the increase of H_2 mole fraction, silicon growth rate increases firstly and then decreases. On the contrary, SiHCl_3 conversion rate and unit energy consumption decrease firstly and then increase. Silicon production rate increases constantly. The optimal H_2 mole fraction is 0.8-0.85. With the growth of silicon rod height, Si HCl3 conversion rate, silicon production rate and silicon growth rate increase, while unit energy consumption decreases. In terms of chemical reaction, the higher the silicon rod is, the better the performance is. In the view of the top-heavy situation, the actual silicon rod height is limited to be below 3 m. With the increase of silicon rod diameter, silicon growth rate decreases firstly and then increases. Besides, SiHCl_3 conversion rate and silicon production rate increase, while unit energy consumption first decreases sharply, then becomes steady. In practice, the bigger silicon rod diameter is more suitable. The optimal silicon rod diameter must be over 120 mm.

Laboratory Investigation of Zinc Recovery fromEAF Dust by Bath Smelting Reduction

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℃.

Kinetics of Reduction of Iron Oxide in CaO-SiO_2-Al_2O_3-Fe_tO Slags with Graphite Powder

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.