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Numerical analysis of thermal plasma scrubber for CF4 decomposition

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Plasma Science and technology 2019年第6期21卷 9-14页

作者： j KO t H KIM S CHOI Department of Nuclear and Energy Engineering Jeju National University Jeju 63243 Republic of Korea Institute for Nuclear Science and technology Jeju National University Jeju 63243 Republic of Korea

CF4 gas emitted in the semiconductor and display manufacturing process is a very harmful greenhouse *** must be removed or converted safely due to its extreme *** a CF4 decomposition system using a thermal plasma scrubber was commercialized,its removal efficiency is *** this work,a numerical analysis of CF4 decomposition in the thermal plasma scrubber was carried out in order to propose an efficient decomposition *** decomposition and recombination temperatures of CF4 were analyzed using thermodynamic equilibrium *** chemical reaction of CF4 decomposition into carbon and fluorine gas was considered in this numerical *** injection position and angle of the CF4 were controlled in order to enhance the decomposition *** vertical injection of CF4 near the torch exit improved the mixing of the CF4 with the thermal plasma *** addition,it was confirmed that the high temperature region expanded due to a vortex generated by strong turbulence in the bottleneck-shaped *** a result,it is revealed that the CF4 injection location and the reactor configuration are the most important factors in improving the decomposition rate.

关键词： numerical simulation decomposition CF4 thermal plasma scrubber

Momentum and heat transfer of a special case of the unsteady stagnation-point flow

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Applied Mathematics and Mechanics(English Edition) 2020年第1期41卷 51-82页

作者： t.G.FANG F.j.WANG Mechanical and Aerospace Engineering Department North Carolina State University

this paper investigates the unsteady stagnation-point flow and heat transfer over a moving plate with mass transfer,which is also an exact solution to the unsteady Navier-Stokes(NS)*** boundary layer energy equation is solved with the closed form solutions for prescribed wall temperature and prescribed wall heat flux *** wall temperature and heat flux have power dependence on both time and spatial *** solution domain,the velocity distribution,the flow field,and the temperature distribution in the fluids are studied for different controlling *** parameters include the Prandtl number,the mass transfer parameter at the wall,the wall moving parameter,the time power index,and the spatial power *** is found that two solution branches exist for certain combinations of the controlling parameters for the flow and heat transfer *** heat transfer solutions are given by the confluent hypergeometric function of the first kind,which can be simplified into the incomplete gamma functions for special *** wall heat flux and temperature profiles show very complicated variation *** wall heat flux can have multiple poles under certain given controlling parameters,and the temperature can have significant oscillations with overshoot and negative values in the boundary *** relationship between the number of poles in the wall heat flux and the number of zero-crossing points is *** difference in the results of the prescribed wall temperature case and the prescribed wall heat flux case is *** given in this paper provide a rare closed form analytical solution to the entire unsteady NS equations,which can be used as a benchmark problem for numerical code validation.

关键词： unsteady stagnation point flow Navier-Stokes(NS)equations analytical solution heat transfer

Grain size and temperature effect on the tensile behavior and deformation mechanisms of non-equiatomic Fe(41)Mn(25)Ni(24)Co8Cr2high entropy alloy

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journal of Materials Science & technology 2020年第7期42卷 190-202页

作者： H.t.jeong W.j.Kim Department of Materials Science and Engineering Hongik UniversityMapo-guSangsu-dong 72-1Seoul121-791Republic of Korea

the effect of the grain size on the tensile properties and deformation mechanisms of a nonequiatomic Fe(41)Mn(25)Ni(24)Co8 Cr2 high-entropy alloy was studied in the temperature range between 298 and 1173 K by preparing the samples with three different grain sizes through severe plastic deformation and subsequent annealing:ultrafine(sub)grain size(≤0.5μm),8.1μm and 590.2μ*** the temperature between 298 and773 K,the material with the large grain size of 590.2μm exhibited the largest tensile ductility(57%-82%)due to its high strain hardening associated with mechanical twinning,but it exhibited the lowest strength due to its large grain *** material with the ultrafine(sub)grain size exhibited the lowest tensile ductility(3%-7%)due to a greatly reduced strain hardening ability after severe plastic deformation,but it exhibited the highest strength due to the dislocation strengthening and grain refinement *** tensile testing at temperatures above 973 K,recrystallization occurred in the material with the ultrafine(sub)grains during the sample heating and holding stage,leading to the formation of fine and equiaxed grains with the sizes of 6.8-13.5μ*** deformation behavior of the Fe(41)Mn(25)Ni(24)Co8 Cr2 with different grain sizes in the high temperature range between 973 and 1173 K,where pseudosteady-state flow was attained in the stress-strain curves,could be explained by considering the simultaneous contribution of grain boundary sliding and dislocation-climb creep to total plastic *** activation energies for plastic flow for the materials with different grain sizes were similar as^199 kj/*** predicting the deformation mechanism,it was important to consider the change in grain size by rapid grain growth or recrystallization during the sample heating and holding stage because grain boundary sliding is a grain-size-dependent deformation *** sample with the ultrafine(sub)grains exhibited the large tensile elongations of 30%-85%due to it

关键词： High entropy alloys Grain size High temperature deformation mechanism tensile behavior Grain boundary sliding

Effects of grain size and Al addition on the activation volume and strain-rate sensitivity of CoCrFeMnNi high-entropy alloy

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journal of Materials Science & technology 2023年第12期143卷 242-252页

作者： H.t.jeong W.j.Kim Department of Materials Science and Engineering Hongik UniversityMapo-guSangsu-dong 72-1Seoul121-791Republic of Korea

the activation volume(V∗)and strain-rate sensitivity exponent(m)of CoCrFeMnNi and Al_(0.5)CoCrFeMnNi high entropy alloys(HEAs)with various grain sizes(ranging between 2.4 and 356μm)were measured at different strain rates and strain levels at room *** the strain rate decreased,the plastic strain decreased,and the grain size increased,V∗*** enhanced solid-solution strengthening by addition of aluminum decreased V∗.the Hassen plot was modified to capture the grain-size depen-dence of V∗by considering the grain-size dependence of the dislocation *** the plastic strain increased,the strain rate decreased,and the grain size decreased,m *** behavior of m could be quantitatively predicted by using equations derived for the grain-size-dependent V∗and flow *** difference in the grain-size dependence of m between conventional face centered cubic(FCC)metals and FCC HEAs over the nanograin size range could not be explained in terms of a relatively large Hall-Petch slope of the FCC HEAs compared with that of the FCC conventional metals,but was explainable in terms of a substantially higher probability of activation of grain-boundary diffusion-controlled grain-boundary-sliding mechanism at nanograin sizes in the FCC conventional metals than in the FCC HEAs.

关键词： Grain size High entropy alloys Activation volume Strain-rate sensitivity Solid solution

Why Don’t We Adequately Identify and Manage Adverse Drug Reactions despite Having the Needed Information?

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Health 2024年第2期16卷 148-159页

作者： Mark j. Kupersmith Karl Kieburtz Department of Neurology Ophthalmology and Neurosurgery Icahn School of Medicine at Mount Sinai New York NY USA Safetherapeutics LLC New York NY USA Clintrex Research Corporation Sarasota FL USA

Importance/Objective: Adverse Drug Reactions (ADRs) are unavoidable, but recognizing and addressing ADRs early can improve wellness and prevent permanent injury. We suggest that available medical information and digital/electronic methods could be used to manage this major healthcare problem for individual patients in real time. Methods: We searched the available digital applications and three literature databases using the medical subject heading terms, adverse drug reaction reporting systems or management, filtered by clinical trial or systemic reviews, to detect publications with data about ADR identification and management approaches. We reviewed the reports that had abstract or summary data or proposed or implemented methods or systems with potential to identify or manage ADRs in clinical settings. Results: the vast majority of the 481 reports used retrospectively collected data for groups of patients or were limited to surveying one population group or class of medication. the reports showed potential and definite associations of ADRs for specific drugs and problems, mostly, but not exclusively, for patients in hospitals and nursing homes. No reports described complete methods to collect comprehensive data on ADRs for individual patients in a healthcare system. the digital applications have ADR information, but all are too cumbersome or incomplete for use in active clinical settings. Several studies suggested that providing information about potential ADRs to clinicians can reduce these problems. Conclusion and Relevance: Although investigators and government agencies agree with the need, there is no comprehensive ADR management program in current use. Informing the patient’s healthcare practitioners of potential ADRs at the point of service has the potential for reduction of these complications, which should improve healthcare and reduce unneeded costs.

关键词： Adverse Drug Reaction Medication Side Effect Identification Medication Complication Medication Safety

Microstructure tailoring of Al_(0.5)CoCrFeMnNi to achieve high strength and high uniform strain using severe plastic deformation and an annealing treatment

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journal of Materials Science & technology 2021年第12期71卷 228-240页

作者： H.t.jeong W.j.Kim Department of Materials Science and Engineering Hongik UniversityMapo-guSangsu-dong 72-1Seoul 121-791Republic of Korea

Ultrafine-grained alloys fabricated by severe plastic deformation(SPD)have high strength but often poor uniform *** via high-ratio differential speed rolling(HRDSR)followed by an annealing treatment was applied to Al_(0.5)CoCrFeMnNi to design the microstructure from which both high strength and high uniform strain can be *** optimized microstructure was composed of an ultrafine-grained FCC matrix(1.7-2μm)with a high fraction of high-angle grain boundaries(61%-66%)and ultrafine BCC particles(with a size of 0.6-1μm and a volume fraction of8%-9.3%)distributed uniformly at the grain boundaries of the FCC *** the severely plastically deformed microstructure,the nucleation kinetics of the BCC phase was *** static recrystallization(CSRX)took place during the annealing process at 1273 *** of the BCC phase particles occurring concurrently with CSRX effectively retarded the grain growth of the FCC *** precipitation of the hard and brittleσphase was,however,*** annealed sample processed by HRDSR with the optimized microstructure exhibited a high tensile strength of over 1 GPa with a good uniform elongation of 14%-20%.these tensile properties are comparable to those of transformation-induced plasticity *** mechanisms of the severely plastically deformed alloy before and after annealing were identified,and each strengthening mechanism contribution was *** calculated results matched well with the experimental results.

关键词： High entropy alloys Severe plastic deformation Uniform ductility High strength Dual phase Annealing

Effect of roll speed ratio on the texture and microstructural evolution of an FCC high-entropy alloy during differential speed rolling

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journal of Materials Science & technology 2022年第16期111卷 152-166页

作者： H.t.jeong W.j.Kim Department of Materials Science and Engineering Hongik UniversityMapo-guSangsu-dong 72-1Seoul 121-791Republic of Korea

A very coarse-grained(335μm)Fe_(41)Mn_(25)Ni_(24)Co_(8)Cr_(2)high-entropy alloy with a single FCC phase was cold rolling to a 80%reduction in thickness using the differential speed rolling technique with various speed ratios(SRs)ranging between 1 and *** the SR was increased,the volume fraction of the region of high-density micro-shear bands increased to accommodate the higher shear *** SR=4,the entire thickness of the sheet was covered with micro-shear bands,and ultrafine(sub)grains with a size of1.4μm were uniformly formed along the shear bands.A continuous dynamic recrystallization(CDRX)mechanism occurred during rolling,and a higher SR accelerated the CDRX *** conventional rolling(at SR=1),a brasstorientation texture with minor components of S{123}and Cutorientations *** higher SRs,shear texture developed as the main type,while the development of rolling texture was *** microstructure at SR=4 obtained after annealing at973 K showed a fully recrystallized microstructure composed of a five times smaller grain size(4μm)with a higher intensity ofγfiber texture compared with that prepared by conventional *** samples processed with high SRs exhibited better tensile properties compared with the conventionally rolled sample in terms of strength and ductility after *** current results demonstrate that by using differential speed rolling with a high SR,one can achieve a significantly finer and more homogeneous microstructure,stronger shear texture,and superior tensile mechanical properties for an FCC high-entropy alloy compared to that obtained by conventional *** strength of the as-rolled and annealed samples was quantitatively explained by considering the contribution of grain size and dislocation density to strengthening.

关键词： High entropy alloys Differential speed rolling texture Grain refinement Strength Severe plastic deformation

Development of a toroidal soft x-ray imaging system and application for investigating three-dimensional plasma on j-tEXt

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Plasma Science and technology 2024年第3期26卷 94-99页

作者：赵传旭李建超张晓卿王能超丁永华杨州军江中和严伟李杨波毛飞越任正康 the j-tEXt team International joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and TechnologySchool of Electrical and Electronic Engineering and School of PhysicsHuazhong University of Science and TechnologyWuhan 430074People's Republic of China Hubei Key Laboratory of Optical Information and Pattern Recognition Wuhan Institute of TechnologyWuhan 430205People's Republic of China International joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and TechnologySchool of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074People's Republic of China

A toroidal soft x-ray imaging(t-SXRI)system has been developed to investigate threedimensional(3D)plasma physics on *** t-SXRI system consists of three sets of SXR *** sets are newly developed and located on the vacuum chamber wall at toroidal positionsφof 126.4°and 272.6°,respectively,while one set was established previously atφ=*** set of SXR arrays consists of three arrays viewing the plasma poloidally,and hence can be used separately to obtain SXR images via the tomographic *** sawtooth precursor oscillations are measured by t-SXRI,and the corresponding images of perturbative SXR signals are successfully reconstructed at these three toroidal positions,hence providing measurement of the 3D structure of precursor *** observed 3D structure is consistent with the helical structure of the m/n=1/1 *** experimental observation confirms that the t-SXRI system is able to observe 3D structures in the j-tEXt plasma.

关键词： SXR imaging j-tEXt tokamak three-dimensional measurement MHD

Unsteady Internal Flow Conditions of Mini-Centrifugal Pump with Splitter Blades

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journal of thermal Science 2013年第1期22卷 86-91页

作者： t. Shigemitsu j. Fukutomi K. Kaji t. Wada Institute of technology and Science The University of Tokushima Graduate School of Advanced technology and Science The University of Tokushima

Mini centrifugal pumps having a diameter smaller than lOOmm are employed in many fields. But the design method for the mini centrifugal pump is not established because the internal flow condition for these small-sized fluid machines is not clarified and conventional theory is not suitable for small-sized pumps. therefore, mini cen- trifugal pumps with simple structure were investigated by this research. Splitter blades were adopted in this re- search to improve the performance and the internal flow condition of mini centrifugal pump which had large blade outlet angle. the original impeller without the splitter blades and the impeller with the splitter blades were prepared for experiment. the performance tests are conducted with these rotors in order to investigate the effect of the splitter blades on performance and internal flow condition of mini centrifugal pump. On the other hand, a three dimensional unsteady numerical flow analysis was conducted to investigate the change of the internal flow according to the rotor rotation. It is clarified from the experimental results that the performance of the mini cen- trifugal pump is improved by the splitter blades. the blade-to-blade low velocity region was suppressed in the case with the splitter blades. In addition to that, the unsteady flows near the volute casing tongue were suppressed due to the splitter blades. In the present paper, the performance of the mini centrifugal pump is shown and the un- steady flow condition is clarified with the results of the numerical flow analysis. Furthermore, the effects of the splitter blades on the performance and the unsteady internal flow condition are investigated.

关键词： Mini-centrifugal pump Unsteady flow condition Performance Splitter blades