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Effect of mixing temperature on microstructure of an Al-Si alloy prepared by controlled diffusion solidification 被引量:1
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作者 Han Xue Ti-jun Chen +3 位作者 Xue-zheng Zhang Guang-li Bi Ying Ma Ren-guo Guan 《China Foundry》 SCIE CAS CSCD 2023年第3期241-252,共12页
The effects of mixing temperature,i.e.,the temperatures of two precursor melts(pure Al and Al-12Si),on the temperature and solute fields of resultant mixture,the nucleation and growth,and the size and morphology of pr... The effects of mixing temperature,i.e.,the temperatures of two precursor melts(pure Al and Al-12Si),on the temperature and solute fields of resultant mixture,the nucleation and growth,and the size and morphology of primary grains during controlled diffusion solidification(CDS) of Al-8Si alloy were investigated by using simulation and calculation.The results indicate that a lower mixing temperature is helpful for achieving more supercooled microscale Al-rich pockets in the mixture,and increasing the width and supercooling degree of supercooling zone in the Al-rich pockets,and thus,the nucleation rate.The nuclei grow up in nondendritic mode,resulting in spheroidal,at least,nondendritic grains.In a successful CDS,the superheat degrees of the two precursor melts should be limited within several degrees,and it is not necessary to extra stipulate the superheat degree of target alloy melt(Al-8Si) when the requirement about Gibbs energies of the three melts is matched.Subsequent observation on casting microstructures shows that the employed simulation and calculation processes are reasonable and the achieved results are reliable. 展开更多
关键词 controlled diffusion solidification Al-Si alloy nucleation and growth SUPERCOOLING nondendritic grains
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Numerical Diffusion Control of a Space-Time Discontinuous Galerkin Method
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作者 Michel Borrel Juliette Ryan 《Communications in Computational Physics》 SCIE 2009年第2期469-483,共15页
Variations on space-time Discontinuous Galerkin(STDG)discretization associated to Runge-Kutta schemes are developed.These new schemes while keeping the original scheme order can improve accuracy and stability.Numerica... Variations on space-time Discontinuous Galerkin(STDG)discretization associated to Runge-Kutta schemes are developed.These new schemes while keeping the original scheme order can improve accuracy and stability.Numerical analysis is made on academic test cases and efficiency of these schemes are shown on propagating pressure waves. 展开更多
关键词 Gas dynamics aeroacoustics discontinuous Galerkin discretization Runge-Kutta schemes numerical diffusion control
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Effect of mixing rate and temperature on primary Si phase of hypereutectic Al-20Si alloy during control ed diffusion solidification(CDS) process 被引量:5
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作者 Yuan-dong Li Xin-long Zhang +3 位作者 Ying Ma Diran Apelian Hong-wei Zhou Xing-hai Liu 《China Foundry》 SCIE CAS 2015年第3期173-179,共7页
Controlled Diffusion Solidification(CDS) is a promising process relied on mixing two liquid alloys of precisely controlled chemistry and temperature in order to produce a predetermined alloy composition. In this study... Controlled Diffusion Solidification(CDS) is a promising process relied on mixing two liquid alloys of precisely controlled chemistry and temperature in order to produce a predetermined alloy composition. In this study, the CDS was employed to prepare hypereutectic Al-20%Si(mass fraction) alloy using Al-30%Si and pure Al of different temperatures. The mixing rate was controlled using three small crucibles with a hole of different diameters in their bottom. The effect of mixing rate and temperature on the microstructure of the primary Si-phase during the mixing of molten Al and Al-30%Si was studied. The results showed that when the diameter of the small crucible bottom hole is 16 mm, a higher mass mixing rate 0.217 kg·s-1 would results in a lower stream velocity 0.414 m·s-1. Conversely a lower mass mixing rate 0.114 kg·s-1(the diameter of the small crucible bottom hole is 8 mm) would result in a higher fluid stream velocity 0.879 m·s-1. A lower mass mixing rate would be better to refine the primary Si than a higher mass mixing rate. Meanwhile, the morphology and distribution of primary Si could also be improved. Especially, when Al-30%Si alloy at 820 °C was mixed with pure Al at 670 °C in the case of a mass mixing rate of 0.114 kg·s-1 and a pouring temperature of 680 °C, the average size of the primary Si phase would be only 18.2 μm. Its morphology would mostly be octahedral and the primary Si would distribute uniformly in the matrix microstructure. The lower mass mixing rate(0.114 kg·s-1) will enhance the broken tendency of Al-30%Si steam and the mixing agitation of resultant melt, so the primary Si phase can be better refined. 展开更多
关键词 controlled diffusion Solidification(CDS) hypereutectic Al-Si alloy mass mixing rate stream velocity primary Si
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KINETICS OF DIFFUSION-CONTROLLED DRUG MATRICES RELEASE SYSTEM
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作者 王绍亭 杨志生 朱云仙 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 1993年第1期12-19,共8页
A refined double integral method has been applied to the problem encountered in the diffu-sion release of a drug from a polymeric matrix.The finite external mass transfer resistance has alsobeen incorporated into the ... A refined double integral method has been applied to the problem encountered in the diffu-sion release of a drug from a polymeric matrix.The finite external mass transfer resistance has alsobeen incorporated into the present analysis.Experimental release rates of 5-fluorouracil fromethylene-vinyl alcohol copolymer into distilled water were measured in order to test the applicabilityof these models.All system parameters were measured by experiments and models were built up.Themodels presented here are much more accurate than Higuchi model and much easier than the exactsolutions.In view of accuracy,the models are almost the same as the exact solutions.The experi-mental release data agree Well with the computed 展开更多
关键词 diffusional controlled RELEASE ethylene- VINYL ALCOHOL COPOLYMER RELEASE KINETICS
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Casting of aluminum-copper based alloy by controled difusion solidiication 被引量:1
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作者 Li Fan Qi-tang Hao Rui-qi Shen 《China Foundry》 SCIE CAS 2015年第2期92-98,共7页
A quaternary alloy (Al-5.0Cu-0.35Mn-0.25Ti, wt.%), having a similar chemical component with ZL205A, was prepared using a controlled diffusion solidification (CDS) process and a conventional casting process. The ef... A quaternary alloy (Al-5.0Cu-0.35Mn-0.25Ti, wt.%), having a similar chemical component with ZL205A, was prepared using a controlled diffusion solidification (CDS) process and a conventional casting process. The effect of the casting process on microstructure and hardness was investigated. The grain morphology and casting defects of the al oy prepared via the conventional casting and CDS were observed and compared at various pouring temperatures. Results show that the CDS process can al eviate the hot tearing defects and reduce the density of porosity, while getting rid of the riser that is general y used for feeding during conventional casting. Structure observations show that the grain morphology of the conventional cast al oy is mainly dendritic, and the grain size decreases when the pouring temperature is decreased, while the CDS cast al oy consists of a large number of spherical grains, which can decrease the thermal cracking tendency and segregation defect, and enhance the hardness of the alloy. 展开更多
关键词 Al alloys conventional casting controlled diffusion solidifi cation casting defect microstructure
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Effect of CaO/SiO_(2) Slag Mass Ratio on Dissolution Rate of Alumina-based Refractory Ceramics
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作者 ZENG Fanbo HUANG Ao +4 位作者 WANG Xinlian LI Shenghao ZHANG Shuzhe QU Pengcheng GU Huazhi 《China's Refractories》 CAS 2023年第1期30-34,共5页
The dissolution of alumina-based refractory ceramics in CaO-Al2O3-SiO_(2)slag melts was performed based on the in-situ observation system of an ultra-high-temperature laser confocal microscope,and the effect of the Ca... The dissolution of alumina-based refractory ceramics in CaO-Al2O3-SiO_(2)slag melts was performed based on the in-situ observation system of an ultra-high-temperature laser confocal microscope,and the effect of the CaO/SiO_(2)slag mass ratio(C/S ratio)on the dissolution rate of alumina-based refractory ceramics was investigated.The results indicate that the dissolution rate increases with an increase of the C/S ratio and is mainly controlled by diffusion.During the early stage of dissolution,for all C/S ratios,the dissolution process conforms to the classical invariant interface approximation model.During the later stage of dissolution,when the C/S ratio is≥6,the dissolution process is significantly different from the model above because of the formation of a thick interfacial layer,which can be explained by dissolution kinetics. 展开更多
关键词 alumina-based refractory ceramics CaO/SiO2 mass ratio dissolution rate diffusion control in-situ observation
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Leaching kinetics of zinc silicate in ammonium chloride solution 被引量:4
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作者 杨声海 李浩 +3 位作者 孙彦伟 陈永明 唐朝波 何静 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第6期1688-1695,共8页
The leaching kinetics of zinc silicate in ammonium chloride solution was investigated. The effects of stirring speed (150?400 r/min), leaching temperature (95-108 ℃, particle size of zinc silicate (61-150 μm... The leaching kinetics of zinc silicate in ammonium chloride solution was investigated. The effects of stirring speed (150?400 r/min), leaching temperature (95-108 ℃, particle size of zinc silicate (61-150 μm) and the concentration of ammonium chloride (3.5-5.5 mol/L) on leaching rate of zinc were studied. The results show that decreasing the particle size of zinc silicate and increasing the leaching temperature and concentration of ammonium chloride can obviously enhance the leaching rate of zinc. Among the kinetic models of the porous solids tested, the grain model with porous diffusion control can well describe the zinc leaching kinetics. The apparent activation energy of the leaching reaction is 161.26 kJ/mol and the reaction order with respect to ammonium chloride is 3.5. 展开更多
关键词 zinc silicate ammonium chloride LEACHING KINETICS porous diffusion control
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基于动力学和扩散分段控制的Mg/H_2O反应模型及数值分析 被引量:3
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作者 周星 张炜 +2 位作者 杨栋 鲍桐 姚汝亮 《国防科技大学学报》 EI CAS CSCD 北大核心 2011年第1期35-38,共4页
为了数值研究宽广温度范围内Mg/H2O的反应特性,分别建立了考虑部分MgO在液滴表面凝聚的Mg/H2O扩散燃烧模型和基于Arrhenius公式的Mg/H2O反应动力学模型。数值研究了Mg/H2O反应速率在扩散控制和化学动力学控制下随反应条件变化的规律。... 为了数值研究宽广温度范围内Mg/H2O的反应特性,分别建立了考虑部分MgO在液滴表面凝聚的Mg/H2O扩散燃烧模型和基于Arrhenius公式的Mg/H2O反应动力学模型。数值研究了Mg/H2O反应速率在扩散控制和化学动力学控制下随反应条件变化的规律。研究结果表明,Mg液滴扩散燃烧时间计算结果与文献值相符;提高温度和水蒸汽浓度有利于扩散燃烧速率增大,增大压强使燃速降低。不同温度段Mg/H2O反应速率控制因素不同,低温段反应速率受动力学控制,高温段反应速率受扩散控制。 展开更多
关键词 水冲压发动机 镁-水反应 扩散控制 化学动力学控制
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Kinetic Investigations on the Leaching of Niobium from a Low-Grade Niobium-Tantalum Ore by Concentrated KOH Solution 被引量:8
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作者 周宏明 郑诗礼 张懿 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2004年第2期202-207,共6页
The leaching kinetics of niobium from a low-grade niobium-tantalum ore by concentrated KOH solu-tion under atmospheric pressure has been studied. Significant effects of reaction temperature, KOH concentration, stirrin... The leaching kinetics of niobium from a low-grade niobium-tantalum ore by concentrated KOH solu-tion under atmospheric pressure has been studied. Significant effects of reaction temperature, KOH concentration, stirring speed, particle size and inass ratio of alkali-to-ore on the dissolution rate of niobium were examined. The experimental data of the leaching rates and the observed effects of the relevant operating variables were well in-terpreted with a shrinking core model under diffusion control. By using the Arrhenius expression, the apparent activation energy for the dissolution of niobium was evaluated. Finally, on the base of the shrinking core model, the rate equation was established. 展开更多
关键词 clean process LEACHING KINETICS KOH niobium-tantalum ore diffusion control
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Kinetics and Mechanism of Interfacial Reaction in a SiC_f/Ti Composite 被引量:7
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作者 Guoxing ZHANG, Qiang KANG, Nanlin SHI, Geping LI and Dong LIInstitute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2003年第5期407-410,共4页
In order to evaluate the interfacial reaction, a SiCf/Ti (TA1) composite was fabricated by a vacuum hot pressing method and then heat-treated in vacuum at 800℃ for up to 100 h. The elemental distributions of C, Si an... In order to evaluate the interfacial reaction, a SiCf/Ti (TA1) composite was fabricated by a vacuum hot pressing method and then heat-treated in vacuum at 800℃ for up to 100 h. The elemental distributions of C, Si and Ti at the interfacial reaction zone were investigated. It was found that the reaction zone occurs during the fabrication process and continuously grows at high temperature because the Si and C atoms diffuse from SiC fibers to the matrix and Ti atoms diffuse in the opposite direction. The growth of the reaction zone is diffusion controlled and the mechanism of the reaction can be described by a reactive diffusion model of solid-state growth of an AmBn layer between two elementary substances A and B. 展开更多
关键词 SiCf/Ti (TA1) composite Interfacial reaction diffusion control
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Kinetics of oxidation-precipitation of cobalt(Ⅱ) from solution by ozone 被引量:1
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作者 田庆华 郭学益 +1 位作者 易宇 李治海 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2010年第S1期42-45,共4页
In order to precipitate cobalt(Ⅱ) in cobalt chloride solution, a novel method using ozone as the precipitant for its strong oxidability was proposed. The results show that the precipitation reaction is diffusion-cont... In order to precipitate cobalt(Ⅱ) in cobalt chloride solution, a novel method using ozone as the precipitant for its strong oxidability was proposed. The results show that the precipitation reaction is diffusion-controlled. The main factors affecting the oxidation rate such as the stirring speed, solution temperature, ozone partial pressure, initial concentration and flow rate were investigated. The kinetics equation of each condition was established. The results indicate that the oxidation rate is independent of the initial concentration or solution temperature. The oxidation rate increases obviously with increasing the stirring speed. The linear relationship between ozone partial pressure or flow rate and oxidation rate is found. 展开更多
关键词 OZONE diffusion control cobalt chloride OXIDATION KINETICS
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Simulation of microstructural evolution in directional solidification of Ti-45at.%Al alloy using cellular automaton method 被引量:1
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作者 Wang Kuangfei Lu Shan +2 位作者 Mi Guofa Li Changyun FU Hengzhi 《China Foundry》 SCIE CAS 2010年第1期47-51,共5页
The microstructural evolution of Ti-45 at.%Al alloy during directional solidification was simulated by applying a solute diffusion controlled solidification model.The obtained results have shown that under high therma... The microstructural evolution of Ti-45 at.%Al alloy during directional solidification was simulated by applying a solute diffusion controlled solidification model.The obtained results have shown that under high thermal gradients the stable primary spacing can be adjusted via branching or competitive growth.For dendritic structures formed under a high thermal gradient,the secondary dendrite arms are developed not very well in many cases due to the branching mechanism under a constrained dendritic growth condition.Furthermore,it has been observed that,with increasing pulling velocity,there exists a cell/dendrite transition region consisting of cells and dendrites,which varies with the thermal gradient in a contradicting way,i.e.increase of the thermal gradient leading to the decrease of the range of the transition region.The simulations agree reasonably well with experiment results. 展开更多
关键词 Ti-Al based alloy directional solidification solute diffusion controlled mode cellular automaton
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环境感应式控制释放开关膜的研究进展 被引量:5
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作者 李艳 褚良银 +3 位作者 朱家骅 曾刚 夏素兰 陈文梅 《高分子材料科学与工程》 EI CAS CSCD 北大核心 2003年第5期37-41,共5页
药物控制释放是目前十分活跃的研究领域,因为它具有长效、高效、靶向、低副作用等特点,因此具有智能开关的环境感应式控制释放膜成了目前膜学与医用高分子材料的研究热点。文中基于大量研究文献,主要综述了温度感应型、pH感应型以及葡... 药物控制释放是目前十分活跃的研究领域,因为它具有长效、高效、靶向、低副作用等特点,因此具有智能开关的环境感应式控制释放膜成了目前膜学与医用高分子材料的研究热点。文中基于大量研究文献,主要综述了温度感应型、pH感应型以及葡萄糖浓度感应型等环境感应式控制释放开关膜的研究进展。 展开更多
关键词 环境感应式 控制释放 开关膜 研究进展 药物控制释放 接枝法 扩散透过率
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Formation Mechanism of PPS as Antireflection Coating
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作者 WANGHai-yan SUNXiao-feng ZHANGYu-xiang LIWei-qiang LUJing-xiao 《Semiconductor Photonics and Technology》 CAS 2005年第1期32-36,39,共6页
The whole chemical etching process on a P-type polycrystalline silicon substrate with resistivity 1-2Ω·cm is described. The formation mechanism of porous polycrystalline silicon(PPS) microstructure was investi... The whole chemical etching process on a P-type polycrystalline silicon substrate with resistivity 1-2Ω·cm is described. The formation mechanism of porous polycrystalline silicon(PPS) microstructure was investigated. Those how the initial pits were formed and an uniform morphology of PPS was obtained are explained. Two types of etching mechanism were characterized as defect control reaction and diffusion control reaction. The morphology formed after the isotropic acidic solution etching with different etching time and HF/HNO3 concentration was compared with the effect of the same etching process after anisotropic alkaline etching. The study showed that the thickness of porous polycrystalline silicon layer with chemical acidic etching entirely depended on the existence of various types of defects. 展开更多
关键词 diffusion control Defect control Point defect Line defect
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Abnormal endogenous pain modulation and somatic and visceral hypersensitivity in female patients with irritable bowel syndrome 被引量:19
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作者 Clive H Wilder-Smith Joan Robert-Yap 《World Journal of Gastroenterology》 SCIE CAS CSCD 2007年第27期3699-3704,共6页
AIM: To investigate the role of endogenous pain modulatory mechanisms in the central sensitization implicated by the visceral hypersensitivity demonstrated in patients with irritable bowel syndrome (IBS). Dysfuncti... AIM: To investigate the role of endogenous pain modulatory mechanisms in the central sensitization implicated by the visceral hypersensitivity demonstrated in patients with irritable bowel syndrome (IBS). Dysfunction of modulatory mechanisms would be expected to also result in changes of somatic sensory function. METHODS: Endogenous pain modulatory mechanisms were assessed using heterotopic stimulation and somatic and visceral sensory testing in IBS. Pain intensities (visual analogue scale, VAS 0-100) during suprathreshold rectal distension with a barostat, cold pressor stimulation of the foot and during both stimuli simultaneously (heterotopic stimulation) were recorded in 40 female patients with IBS and 20 female healthy controls. RESULTS: Rectal hypersensitivity (defined by 95% Cl of controls) was seen in 21 (53%), somatic hypersensitivity in 22 (55%) and both rectal and somatic hypersensitivity in 14 of these IBS patients. Heterotopic stimulation decreased rectal pain intensity by 6 (-11 to -1) in controls, but increased rectal pain by 2 (-3 to +6) in all IBS patients (P 〈 0.05) and by 8 (-2 to +19) in IBS patients with somatic and visceral hypersensitivity (P 〈 0.02). CONCLUSION: A majority of IBS patients had abnormal endogenous pain modulation and somatic hypersensitivity as evidence of central sensitization. 展开更多
关键词 Diffuse noxious inhibitory controls Endogenous pain modulation HYPERSENSITIVITY Irritable Bowel Syndrome Quantitative sensory testing Visceral pain SENSITIZATION
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CONVERGENCE RATES OF MARKOV CHAIN APPROXIMATION METHODS FOR CONTROLLED DIFFUSIONS WITH STOPPING
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作者 Qingshuo SONG Gang George YIN 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2010年第3期600-621,共22页
This work is concerned with rates of convergence of numerical methods using Markov chainapproximation for controlled diffusions with stopping (the first exit time from a bounded region).In lieuof considering the assoc... This work is concerned with rates of convergence of numerical methods using Markov chainapproximation for controlled diffusions with stopping (the first exit time from a bounded region).In lieuof considering the associated finite difference schemes for Hamilton-Jacobi-Bellman (HJB) equations,a purely probabilistic approach is used.There is an added difficulty due to the boundary condition,which requires the continuity of the first exit time with respect to the discrete parameter.To prove theconvergence of the algorithm by Markov chain approximation method,a tangency problem might arise.A common approach uses certain conditions to avoid the tangency problem.Here,by modifying thevalue function,it is demonstrated that the tangency problem will not arise in the sense of convergencein probability and in L^1.In addition,controlled diffusions with a discount factor is also treated. 展开更多
关键词 controlled diffusion dynamic programming equation Markov chain approximation rate of convergence.
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Diffusion-reaction compromise the polymorphs of precipitated calcium carbonate 被引量:3
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作者 Han Wang Wenlai Huang Yongsheng Han 《Particuology》 SCIE EI CAS CSCD 2013年第3期301-308,共8页
Diffusion is seldom considered by chemists and materialists in the preparation of materials while it plays an important role in the field of chemical engineering. If we look at crystallization at the atomic level, cry... Diffusion is seldom considered by chemists and materialists in the preparation of materials while it plays an important role in the field of chemical engineering. If we look at crystallization at the atomic level, crystal growth in a solution starts from the diffusion of ions to the growing surface followed by the incorporation of ions into its lattice. Diffusion can be a rate determining step for the growth of crystals. In this paper, we take the crystallization of calcium carbonate as an example to illustrate the microscopic processes of diffusion and reaction and their compromising influence on the morphology of the crystals produced. The diffusion effect is studied in a specially designed three-cell reactor. Experiments show that a decrease of diffusion leads to retardation of supersaturation and the formation of a continuous concen- tration gradient in the reaction cell, thus promoting the formation of cubic calcite particles. The reaction rate is regulated by temperature. Increase of reaction rate favors the formation of needle-like aragonite particles. When diffusion and reaction play joint roles in the reaction system, their compromise dominates the formation of products, leading to a mixture of cubic and needle-like particles with a controllable ratio. Since diffusion and reaction are universal factors in the preparation of materials, the finding of this paper could be helpful in the controlled synthesis of other materials. 展开更多
关键词 Calcium carbonate Shape control Crystallization diffusion Compromise
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Numerical Solutions for Optimal Control of Stochastic Kolmogorov Systems
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作者 YIN George WEN Zhexin +1 位作者 QIAN Hongjiang NGUYEN Huy 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2021年第5期1703-1722,共20页
This work is concerned with controlled stochastic Kolmogorov systems.Such systems have received much attention recently owing to the wide range of applications in biology and ecology.Starting with the basic premise th... This work is concerned with controlled stochastic Kolmogorov systems.Such systems have received much attention recently owing to the wide range of applications in biology and ecology.Starting with the basic premise that the underlying system has an optimal control,this paper is devoted to designing numerical methods for approximation.Different from the existing literature on numerical methods for stochastic controls,the Kolmogorov systems take values in the first quadrant.That is,each component of the state is nonnegative.The work is designing an appropriate discrete-time controlled Markov chain to be in line with(locally consistent)the controlled diffusion.The authors demonstrate that the Kushner and Dupuis Markov chain approximation method still works.Convergence of the numerical scheme is proved under suitable conditions. 展开更多
关键词 controlled diffusion controlled Markov chain Kolmogorov equation numerical approximation
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Near-Optimal Controls of Differential Systems with Switching and Random Jumps Subject to Fast Switching and Wideband Noise Perturbation
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作者 G.YIN Xian-ping GUO +1 位作者 Yousef TALAFHA Nicholas A.BARAN 《Acta Mathematicae Applicatae Sinica》 SCIE CSCD 2016年第1期17-34,共18页
This work develops near-optimal controls for systems given by differential equations with wideband noise and random switching.The random switching is modeled by a continuous-time,time-inhomogeneous Markov chain.Under ... This work develops near-optimal controls for systems given by differential equations with wideband noise and random switching.The random switching is modeled by a continuous-time,time-inhomogeneous Markov chain.Under broad conditions,it is shown that there is an associated limit problem,which is a switching jump diffusion.Using near-optimal controls of the limit system,we then build controls for the original systems.It is shown that such constructed controls are nearly optimal. 展开更多
关键词 regime switching jump diffusion wideband noise martingale problem relaxed control near-optimal control
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Kinetic study of electrochemically produced hydrogen bubbles on Pt electrodes with tailored geometries 被引量:2
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作者 Jingshan Qin Tianhui Xie +8 位作者 Daojin Zhou Liang Luo Zhengyi Zhang Zhicheng Shang Jiawei Li Lagnamayee Mohapatra Jinwen Yu Haijun Xu Xiaoming Sun 《Nano Research》 SCIE EI CSCD 2021年第7期2154-2159,共6页
Understanding bubbles evolution kinetics on electrodes with varied geometries is of fundamental importance for advanced electrodes design in gas evolution reaction.In this work,the evolution kinetics of electro-genera... Understanding bubbles evolution kinetics on electrodes with varied geometries is of fundamental importance for advanced electrodes design in gas evolution reaction.In this work,the evolution kinetics of electro-generated hydrogen bubbles are recorded in situ on three(i.e.smooth,nanoporous,and nanoarray)Pt electrodes to identify the geometry dependence.The bubble radius shows a time-dependent growth kinetic,which is tightly-connected to the electrode geometry.Among the three electrodes,the smooth one shows a typical time coefficient of 0.5,in consistence with reported values;the nanoporous one shows a time coefficient of 0.47,less than the classic one(0.5);while the nanoarray one exhibits fastest bubble growth kinetics with a time coefficient higher than 0.5(0.54).Moreover,the nanoarray electrode has the smallest bubble detachment size and the largest growth coefficient(23.3)of all three electrodes.Based on the experimental results,a growth model combined direct bottom-injection with micro-convection is proposed to illustrate the surface geometry dependent coefficients,i.e.,the relationship between geometry and bubble evolution kinetics.The direct injection of generated gas molecules from the bottom of bubbles at the three phase boundaries are believed the key to tailor the bubble wetting states and thus determine the bubble evolution kinetics. 展开更多
关键词 hydrogen bubble evolution growth kinetics surface geometry solid surface diffusion controlled
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