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2 Electroreduction Applications of Atomically Dispersed Metallic Materials
Published in Wei Yan, Xifei Li, Shuhui Sun, Xueliang Sun, Jiujun Zhang, Atomically Dispersed Metallic Materials for Electrochemical Energy Technologies, 2023
In a recent work by Xin et al. [67], Zn single atoms supported on microporous N-doped carbon (SA–Zn/MNC) were fabricated. Different from the above-reported results, the Zn–N4 sites in SA–Zn/MNC were active in producing CH4 from ECR. At −1.8 V vs. the saturated calomel electrode (SCE), a FE of 85% with a CH4 partial current density of 31.8 mA cm−2 was achieved. Mechanistic study implied that the O atom in the *OCHO intermediate could bond to Zn single atom more easily than the C atom, thus blocking the formation of CO and facilitating the production of CH4. In addition, the SA–Zn/MNC displayed stable ECR performance during electrolysis of 35 h, which was benefited from the MNC support with rapid charge transport, easy access to the active sites as well as high stability.
Modeling of Cutting Forces During Machining
Published in C.W. de Silva, Mechatronic Systems, 2007
Z.G. Wang, M. Rahman, Y.S. Wong, K.S. Neo, J. Sun, H. Onozuka
Mechanistic models are based on the relationship between the cutting forces and the undeformed area of cut, cutting tool geometry, cutting conditions, and workpiece geometry. The cutting force is usually assumed to be proportional to the undeformed area of cut. This mechanistic approach works without knowing parameters of the cutting force mechanics, such as shear angle, shear stress, and friction angle, and it is widely used. However, these models are commonly computer based and depend heavily on empirical cutting data for their modeling capacity [1]. Strictly speaking then, the mechanistic model is not a completely analytical model, because of its reliance on empirical cutting data.
The Interaction of Fission Product Vapors with Aerosols in Severe Reactor Accidents
Published in J. T. Rogers, Fission Product Transport Processes in Reactor Accidents, 2020
Christopher G. Benson, Brian R. Bowsher, Alan L. Nichols
Physico-chemical reactions between the fission product vapours and bulk aerosols could have a major effect on the transport characteristics of the radioactive emission from a severe reactor accident. These effects could be included in mechanistic calculations in order to assess the radiobiological consequences of a severe accident. However, further experimental studies are required to obtain thermodynamic and kinetic data for a number of important vapour-aerosol systems.
Multimodal data fusion for systems improvement: A review
Published in IISE Transactions, 2022
Nathan Gaw, Safoora Yousefi, Mostafa Reisi Gahrooei
Mathematical model parameter estimation: Another class of hybridization methods uses machine learning to provide an estimate of some parameters for a mathematical/physical model to better inform the prediction capabilities. To make the model more patient-specific, Clifton et al. (2017) used statistical linear estimation to fine-tune parameters for a mechanistic model of mobile health intervention in chronic pain. Meng et al. (2019) used machine learning to estimate parameters of a mechanistic model of cane sugar crystallization. Dong et al. (2016) utilized a statistical model to estimate parameters for a mechanistic model to improve forecasting of residential electricity. Mak et al. (2018) utilized Gaussian processes to estimate parameters in a mechanistic model to quantify turbulent flows in swirl injectors with varying geometries.
Analysis of cutting forces at different spindle speeds with straight and helical-flute tools for conventional-speed milling incorporating the effect of tool runout
Published in Mechanics Based Design of Structures and Machines, 2022
In mechanistic model, cutting forces are proportional to undeformed chip area (Altintas 2000). Kline and DeVor (1983) presented a mechanistic model to predict milling forces for the cutting geometry with tool runout. They calibrated the empirical coefficients with the measured average forces and an undeformed chip thickness approach, which are referred to as force coefficients. Based on a similar mechanistic cutting force model considering the cutter edge trajectories with runout effect, Lu et al. (2018) determined the cutting forces for micro flat-end milling. A general approach was established by Wan and Zhang (2006) for cutting force prediction in milling operations, who included the influences of the tool and workpiece and immersion angle variation. Montgomery and Altintas (1991) proposed a theoretical cutting force method which describes the undeformed chip thickness from the trochoidal motion of the tool. Recently, Wojciechowski (2015) investigated cutting forces in ball-end milling of inclined surfaces by including the effect of surface inclination and tool runout. However, in die and mold making operations, where cutting conditions change, a variety of cut tests are necessary to determine the cutting forces. Considering the cutting tool, workpiece and cutting parameters, a systematic investigation of the influences of tool runout on the milling process based upon trochoidal flute trajectories should be performed.
Identification of the most stable silver cluster ions produced under plasma solution conditions
Published in Molecular Physics, 2021
Leighton O. Jones, Chelsea M. Mueller, Peter Bruggeman, George C. Schatz
The thermodynamic reaction pathway for silver nanoparticles under plasma conditions was elucidated with theoretical calculations. The approach was twofold: first the use of atomistic calculations to determine a mechanistic atom by atom pathway, then analyse competing dimer-dimer and dimer-trimer reactions. A couple of surprising finds were observed: (i) the most thermodynamically favourable reaction path involved intermediate structures that were neither the most neutral, nor the most charged, but in between; (ii) the species 1Ag42+ is favourable, in line with a recent kinetic model using a reduced reaction set [31] based on experimentally obtained reaction rates [13,33]. Both results can be rationalised as arising from species that are stabilised by sigma aromaticity. However, this effect does not control the dominant species having five silver atoms. The results here suggest other ions such as 1Ag3+ and 2Ag52+ that have not been studied so far should be present in quantities suitable enough to be observed. Further, we have provided optical spectra for these clusters that suggest that their detection should be possible. Future work involves modifying the results identified here to study the growth processes under alternative plasma electron sources, such as those producing atomic hydrogen or hydroxyl radicals. We will also study larger clusters to see if aromaticity provides a useful tool for identifying growth paths.