Academic literature on the topic 'Pseudo-first order rate expression'
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Journal articles on the topic "Pseudo-first order rate expression"
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Khaloo, Shokooh Sadat, Amir Hossein Matin, Sahar Sharifi, Masoumeh Fadaeinia, Narges Kazempour, and Shaghayegh Mirzadeh. "Equilibrium, kinetic and thermodynamic studies of mercury adsorption on almond shell." Water Science and Technology 65, no. 8 (April 1, 2012): 1341–49. http://dx.doi.org/10.2166/wst.2012.767.
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The application of almond shell as a low cost natural adsorbent to remove Hg2+ from aqueous solution was investigated. Batch experiments were carried out to evaluate the adsorption capacity of the material. The chemical and physical parameters such as pH, sorbent amount, initial ion concentration, and contact time were optimized for the maximum uptake of mercury onto the solid surface. Adsorption isotherms were expressed by Langmuir and Freundlich adsorption models, and the experimental data were found to fit the Langmuir model rather than the Freundlich. The maximum adsorption capacity obtained from the Langmuir isotherm was 135.13 mg/g. A kinetic study was carried out with pseudo-first-order and pseudo-second-order reaction equations and it was found that the Hg2+ uptake process followed the pseudo-second-order rate expression. The thermodynamic values, ΔG0, ΔH0 and ΔS0, indicated that adsorption was an endothermic and spontaneous process. The potential of this material for mercury elimination was demonstrated by efficient Hg2+ removal from a synthetic effluent.
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Ervin, J. S., and S. P. Heneghan. "The Meaning of Activation Energy and Reaction Order in Autoaccelerating Systems." Journal of Engineering for Gas Turbines and Power 120, no. 3 (July 1, 1998): 468–73. http://dx.doi.org/10.1115/1.2818168.
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Global reaction mechanisms and rate constants are commonly used in computational fluid dynamics models that incorporate chemical reactions to study aviation fuel thermal and oxidative thermal stability. Often these models are calibrated using one set of conditions, such as flow rate and temperature. New conditions are then calculated by extrapolation using the global expressions. A close inspection of the origin of global oxidation rate constants reveals that in systems that undergo autocatalysis or auto inhibition, a simple overall global activation energy and reaction order are not good descriptors of the reaction process. Furthermore, pseudo-detailed chemical kinetic modeling of a fuel that experiences autocatalysis shows that the observed reaction order for oxygen consumption varies with initial oxygen concentration, extent of reaction, and temperature. Thus, a simple global rate expression used to describe oxygen consumption in an autoaccelerating system is insufficient to allow extrapolation to different temperature or time regimes.
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Talukdar, R. K., L. Zhu, K. J. Feierabend, and J. B. Burkholder. "Rate coefficients for the reaction of methylglyoxal (CH<sub>3</sub>COCHO) with OH and NO<sub>2</sub> and glyoxal (HCO)<sub>2</sub> with NO<sub>3</sub>." Atmospheric Chemistry and Physics Discussions 11, no. 6 (June 27, 2011): 18211–48. http://dx.doi.org/10.5194/acpd-11-18211-2011.
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Abstract. Rate coefficients, k, for the gas-phase reaction of CH3COCHO (methylglyoxal) with the OH and NO3 radicals and (CHO)2 (glyoxal) with the NO3 radical are reported. Rate coefficients for the OH + CH3COCHO (k1) reaction were measured under pseudo-first-order conditions in OH as a function of temperature (211–373 K) and pressure (100–220 Torr, He and N2 bath gases) using pulsed laser photolysis to produce OH radicals and laser induced fluorescence to measure its temporal profile. k1 was found to be independent of the bath gas pressure with k1(295 K) = (1.29 ± 0.13) × 10−11 cm3 molecule−1 s−1 and a temperature dependence that is well represented by the Arrhenius expression k1(T) = (1.74 ± 0.20) × 10−12 exp[(590 ± 40)/T] cm3 molecule−1 s−1 where the uncertainties are 2σ and include estimated systematic errors. Rate coefficients for the NO3+ (CHO)2 (k3) and NO3+ CH3COCHO (k4) reactions were measured using a relative rate technique to be k3(296 K) = (3.7 ± 1.0) × 10−16 cm3 molecule−1 s−1 and k4(296 K) = (4.1 ± 1.2) × 10−16 cm3 molecule−1 s−1. k3(T) was also measured using an absolute rate coefficient method under pseudo-first-order conditions at 296 and 353 K to be (4.2 ± 0.8) × 10−16 and (7.9 ± 3.6) × 10−16 cm3 molecule−1 s−1, respectively, in agreement with the relative rate result obtained at room temperature. The atmospheric implications of the OH and NO3 reaction rate coefficients measured in this work are discussed.
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Talukdar, R. K., L. Zhu, K. J. Feierabend, and J. B. Burkholder. "Rate coefficients for the reaction of methylglyoxal (CH<sub>3</sub>COCHO) with OH and NO<sub>3</sub> and glyoxal (HCO)<sub>2</sub> with NO<sub>3</sub>." Atmospheric Chemistry and Physics 11, no. 21 (November 2, 2011): 10837–51. http://dx.doi.org/10.5194/acp-11-10837-2011.
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Abstract. Rate coefficients, k, for the gas-phase reaction of CH3COCHO (methylglyoxal) with the OH and NO3 radicals and (CHO)2 (glyoxal) with the NO3 radical are reported. Rate coefficients for the OH + CH3COCHO (k1) reaction were measured under pseudo-first-order conditions in OH as a function of temperature (211–373 K) and pressure (100–220 Torr, He and N2 bath gases) using pulsed laser photolysis to produce OH radicals and laser induced fluorescence to measure its temporal profile. k1 was found to be independent of the bath gas pressure with k1(295 K) = (1.29 ± 0.13) × 10−11 cm3 molecule−1 s−1 and a temperature dependence that is well represented by the Arrhenius expression k1(T) = (1.74 ± 0.20) × 10−12 exp[(590 ± 40)/T] cm3 molecule−1 s−1 where the uncertainties are 2σ and include estimated systematic errors. Rate coefficients for the NO3 + (CHO)2 (k3) and NO3 + CH3COCHO (k4) reactions were measured using a relative rate technique to be k3(296 K) = (4.0 ± 1.0) × 10−16 cm3 molecule−1 s−1 and k4(296 K) = (5.1 ± 2.1) × 10−16 cm3 molecule−1 s−1. k3(T) was also measured using an absolute rate coefficient method under pseudo-first-order conditions at 296 and 353 K to be (4.2 ± 0.8) × 10−16 and (7.9 ± 3.6) × 10−16 cm3 molecule−1 s−1, respectively, in agreement with the relative rate result obtained at room temperature. The atmospheric implications of the OH and NO3 reaction rate coefficients measured in this work are discussed.
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Yusuf Ibrahim, Yusuf Usman Jibrin, Zaharaddeen Muhammad, and Mujahid Abubakar. "PHOTOCATALYTIC OPTIMIZATION OF MR DYE BY K-ZnO AND ZnO CATALYSTS UNDER VISIBLE IRRADIATION." FUDMA JOURNAL OF SCIENCES 4, no. 4 (June 12, 2021): 67–76. http://dx.doi.org/10.33003/fjs-2020-0404-408.
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The lucubration on the visible light methyl red (MR) degradation using K-ZnO and undoped ZnO photo catalyst was investigated. The successive formation of K-ZnO was ascertained by several techniques such as scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and UV-Visible spectrophotometer and solid state UV-Vis band gap energy determination by comparing the Kubelka-Monk equation with Tauc equation and the energy band gap was calculated to be 3.28ev. The influence of reaction variables such as MR concentration, reaction pH, catalyst loadings and temperature have been investigated for both process. The kinetics model was developed for both doped and undoped ZnO photocatalyst using pseudo first and second order kinetics, the result indicated that both doped and undoped ZnO followed pseudo first order kinetics due to higher correlation coefficient (R2) value of 0.985 and 0.922 with rate constant (k) of 0.026 min-1 and 0.062 min-1, respectively. Based on the rate constant value (k) obtained at different reaction temperatures, the Arrhenius expression was derived. The derived activation energy (Ea) for the degradation of MR by K-ZnO photocatalysis was 32.109x103JK-1. The optimum condition for K-ZnO showed nearly complete degradation (95%) of the dye molecules with slightly higher degradation efficiency compares to ZnO (91%).
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Mahaboob, B., J. PeterPraveen, J. Ravi Sankar, B. Venkateswarlu, and C. Narayana. "A Memoir on Nonlinear Regression Model and its Pseudo Model." International Journal of Engineering & Technology 7, no. 4.10 (October 2, 2018): 995. http://dx.doi.org/10.14419/ijet.v7i4.10.26643.
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The main objective of this article is to specify a nonlinear regression model, formulate the assumptions on them and aquire its linear pseudo model. A model may be considered a mathematical description of a physical, chemical or biological state or process. Many models used in applied mathematics and Mathematical statistics are nonlinear in nature one of the major topics in the literature of theoretical and applied mathematics is the estimation of parameters of nonlinear regression models. A perfect model may have to many parameters to be useful. Nonlinear regression models have been intensively studied in the last three decades. Junxiong Lin et.al [1] , in their paper, compared best –fit equations of linear and nonlinear forms of two widely used kinetic models, namely pseudo-first order and pseudo=second-order equations. K. Vasanth kumar [2], in his paper, proposed five distinct models of second order pseudo expression and examined a comparative study between method of least squares for linear regression models and a trial and error nonlinear regression procedures of deriving pseudo second order rare kinetic parameters. Michael G.B. Blum et.al [3] proposed a new method which fits a nonlinear conditional heteroscedastic regression of the parameter on the summary statistics and then adaptively improves estimation using importance sampling.
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Rabehasaina, Landy, and Bruno Sericola. "A second-order Markov-modulated fluid queue with linear service rate." Journal of Applied Probability 41, no. 03 (September 2004): 758–77. http://dx.doi.org/10.1017/s0021900200020532.
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We consider an infinite-capacity second-order fluid queue governed by a continuous-time Markov chain and with linear service rate. The variability of the traffic is modeled by a Brownian motion and a local variance function modulated by the Markov chain and proportional to the fluid level in the queue. The behavior of this second-order fluid-flow model is described by a linear stochastic differential equation, satisfied by the transient queue level. We study the transient level's convergence in distribution under weak assumptions and we obtain an expression for the stationary queue level. For the first-order case, we give a simple expression of all its moments as well as of its Laplace transform. For the second-order model we compute its first two moments.
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Rabehasaina, Landy, and Bruno Sericola. "A second-order Markov-modulated fluid queue with linear service rate." Journal of Applied Probability 41, no. 3 (September 2004): 758–77. http://dx.doi.org/10.1239/jap/1091543424.
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We consider an infinite-capacity second-order fluid queue governed by a continuous-time Markov chain and with linear service rate. The variability of the traffic is modeled by a Brownian motion and a local variance function modulated by the Markov chain and proportional to the fluid level in the queue. The behavior of this second-order fluid-flow model is described by a linear stochastic differential equation, satisfied by the transient queue level. We study the transient level's convergence in distribution under weak assumptions and we obtain an expression for the stationary queue level. For the first-order case, we give a simple expression of all its moments as well as of its Laplace transform. For the second-order model we compute its first two moments.
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Rusdiarso, Bambang, Rahmat Basuki, and Sri Juari Santosa. "Evaluation of Lagergren Kinetics Equation by Using Novel Kinetics Expression of Sorption of Zn2+ onto Horse Dung Humic Acid (HD-HA)." Indonesian Journal of Chemistry 16, no. 3 (March 12, 2018): 338. http://dx.doi.org/10.22146/ijc.21151.
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Extraction and purification of humic acid from dry horse dung powder (HD-HA) was performed successfully and the purified HD-HA was then applied as sorbent to adsorb Zn2+. Extraction and purification were performed based on procedure of Stevenson (1994) under atmospheric air. Parameters investigated in this work consist of effect of medium sorption acidity, sorption rate (ka) and desorption rate constant (kd), Langmuir (monolayer) and Freundlich (multilayer) sorption capacities, and energy (E) of sorption. The ka and kd were determined according to the kinetic model of second order sorption reaching equilibrium, monolayer sorption capacity (b) and energy (E) were determined according to Langmuir isotherm model, and multilayer sorption capacity (B) was determined based on Freundlich isotherm model. Sorption of Zn2+ on purified HD-HA was maximum at pH 5.0. The novel kinetic expression resulted from proposed kinetic model has been shown to be more applicable than the commonly known Lagergren equation obtained from the pseudo-first order sorption model. The application of the equation revealed that the intercept of Lagergren equation, ln qe was more complex function of initial concentration of Zn2+ (a), Langmuir sorption capacity (b), and sorbed Zn2+ at equilibrium (xe).
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Liu, Ting Yi, Zhong Liang Wang, and Xiao Xing Yan. "Enhanced Cr(VI) Removal from Landfill Leachates Using Nanoscale Zero-Valent Iron." Advanced Materials Research 905 (April 2014): 12–18. http://dx.doi.org/10.4028/www.scientific.net/amr.905.12.
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Nanoscale zero-valent iron modified by citric acid (m-NZVI) was used to remove hexavalent chromium (Cr (VI)) from landfill leachates. Citric acid was useful to enhance the dispersion of NZVI. The results demonstrated that the m-NZVI particles were uniform with a mean diameter of 45.6 nm and the specific surface area was about 22.8 m2/g. The Cr (VI) removal rates increased as an increase of the dosage of m-NZVI and the temperature but decreased as an increase of pH and the initial concentration of HA. Cr (VI) adsorption kinetics followed a pseudo-first-order rate expression and the reaction rate constants ranged from 0.05 to 0.32 min-1. X-ray photoelectron spectroscope (XPS) analysis confirmed that the Fe (III)-critic acid and/or Cr (III)-HA compounds were formed on the m-NZVI surface, which could hinder the formation of Fe (III)-Cr (III) compounds. It was also shown that removing Cr (VI) by m-NZVI was a chemical controlled and irreversible process.
Dissertations / Theses on the topic "Pseudo-first order rate expression"
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Yalala, Bongani Ndhlovu. "Ion exchange resins an functional fibres :a comparative study for the treatment of brine waste water." Thesis, University of the Western Cape, 2009. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_8342_1298358875.
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To improve the adsorption capacity of polyacrylonitrile (PAN) fibres, hydrophilic amidoxime fibres were prepared by subsequent conversion of the cyano groups to an amidoxime group by reacting with hydroxylamine at 80°
C at an optimum amidoximation time of 2 hrs. The amidoxime fibre was hydrolyzed/alkali treated in a solution of sodium hydroxide to enhance or improve the adsorption properties. This was followed by characterization of the amidoxime and hydrolyzed fibres using Scanning electron microscopy (SEM)
Fourier transform Infrared Spectroscopy (FTIR) and exchange capacity (cationic and anionic). SEM showed that the hydrolysis process made the surface of Amidoxime fibre rougher than that of Polyacrylonitrile fibre. FTIR revealed that the hydrolyzed Amidoxime fibres contained conjugated imine (-C=N-) sequences. Functionalization enhanced the sorption of amidoxime fibres by an increase of 20 % in the cationic exchange capacity. This was achieved by the part conversion of the cyano groups into the carboxylic acid groups. The fibres showed faster kinetics largely due the available exchange sites on the surface of the fibres hence the equilibration was achieved much quicker.
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Tshabalala, Oupa Samuel. "The development of FT-Raman techniques to quantify the hydrolysis of Cobalt (III) nitrophenylphosphate complexes using multivariate data analysis." Diss., 2007. http://hdl.handle.net/10500/23202.
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The FT-Raman techniques were developed to quantify reactions that
follow on mixing aqueous solutions of bis-(1,3-diaminopropane)diaquacobalt(
III) ion ([Co(tn)2(0H)(H20)]2+) and p-nitrophenylphosphate
(PNPP).
For the development and validation of the kinetic modelling
technique, the well-studied inversion of sucrose was utilized. Rate
constants and concentrations could be estimated using calibration
solutions and modelling methods. It was found that the results
obtained are comparable to literature values. Hence this technique
could be further used for the [Co(tn)2(0H)(H20)]2+ assisted
hydrolysis of PNPP.
It was found that rate constants where the pH is maintained at 7.30
give results which differ from those where the pH is started at 7.30
and allowed to change during the reaction. The average rate
constant for 2:1 ([Co(tn)2(0H)(H20)]2+:PNPP reactions was found to
be approximately 3 x 104 times the unassisted PNPP hydrolysis rate.Chemistry
M. Sc. (Chemistry)
Books on the topic "Pseudo-first order rate expression"
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Bell, Duncan. Dreamworlds of Race. Princeton University Press, 2020. http://dx.doi.org/10.23943/princeton/9780691194011.001.0001.
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Between the late nineteenth century and the First World War an ocean-spanning network of prominent individuals advocated the unification of Britain and the United States. They dreamt of the final consolidation of the Angloworld. Scholars, journalists, politicians, businessmen, and science fiction writers invested the “Anglo-Saxons” with extraordinary power. The most ambitious hailed them as a people destined to bring peace and justice to the earth. More modest visions still imagined them as likely to shape the twentieth century. This book explores this remarkable moment in the intellectual history of racial domination, political utopianism, and world order. Focusing on a quartet of extraordinary figures, the book shows how unionists on both sides of the Atlantic reimagined citizenship, empire, patriotism, race, war, and peace in their quest to secure global supremacy. Yet even as they dreamt of an Anglo-dominated world, the unionists disagreed over the meaning of race, the legitimacy of imperialism, the nature of political belonging, and the ultimate form and purpose of unification. The racial dreamworld was an object of competing claims and fantasies. Exploring speculative fiction as well as more conventional forms of political writing, the author reads unionist arguments as expressions of the utopianism circulating through fin-de-siècle Anglo-American culture, and juxtaposes them with pan-Africanist critiques of racial domination and late twentieth-century fictional narratives of Anglo-American empire. Tracing how intellectual elites promoted an ambitious project of political and racial unification between Britain and the United States, the book analyzes ideas of empire and world order that reverberate to this day.
Book chapters on the topic "Pseudo-first order rate expression"
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Goyani, Mahesh. "Nonverbal Communication through Facial Expression in Diverse Conditions." In Types of Nonverbal Communication [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.95109.
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In this chapter, we investigated computer vision technique for facial expression recognition, which increase both - the recognition rate and computational efficiency. Local and global appearance-based features are combined in order to incorporate precise local texture and global shapes. We proposed Multi-Level Haar (MLH) feature based system, which is simple and fast in computation. The driving factors behind using the Haar were its two interesting properties - signal compression and energy preservation. To depict the importance of facial geometry, we first segmented the facial components like eyebrows, eye, and mouth, and then applied feature extraction on these facial components only. Experiments are conducted on three well known publicly available expression datasets CK, JAFFE, TFEID and in-house WESFED dataset. The performance is measured against various template matching and machine learning classifiers. We achieved highest recognition rate for proposed operator with Discriminant Analysis Classifier. We studied the performance of proposed approach in several scenarios like expression recognition from low resolution, recognition from small training sample space, recognition in the presence of noise and so forth.
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Bhowmik, Mrinal Kanti, Priya Saha, Goutam Majumder, and Debotosh Bhattacharjee. "Decision Fusion of Multisensor Images for Human Face Identification in Information Security." In Handbook of Research on Computational Intelligence for Engineering, Science, and Business, 571–91. IGI Global, 2013. http://dx.doi.org/10.4018/978-1-4666-2518-1.ch022.
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The chapter is mainly focused on theoretical discussions and experimental observations on decision fusion along with feature level multisensor fusion technique for human face identification especially useful in information security system in order to obtain better recognition rate. Feature level multisensor fusion of optical and infrared images is performed to resolve the difficulties of individual interpretation of visual and infrared images as a first step of the face identification system. ROC curve analysis is also reported to verify the recognition accuracy after classification of fused images using Support Vector Machine (SVM). The authors have performed experiments on IRIS face database in three different groups: full dataset, and two subsets with variation in expression and illumination. Classification accuracy was obtained in two subsets and full dataset as 95%, 94.12%, and 99.08%, respectively after decision fusion.
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Aishah, Abdul Razak, Izani Zainal Abidin Mohamad, and Ryoichi Komiya. "Voice Driven Emotion Recognizer Mobile Phone." In Web Engineering Advancements and Trends, 144–59. IGI Global, 2010. http://dx.doi.org/10.4018/978-1-60566-719-5.ch008.
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This article proposes an application of emotion recognizer system in telecommunications entitled voice driven emotion recognizer mobile phone (VDERM). The design implements a voice-to-image conversion scheme through a voice-to-image converter that extracts emotion features in the voice, recognizes them, and selects the corresponding facial expression images from image bank. Since it only requires audio transmission, it can support video communication at a much lower bit rate than the conventional videophone. The first prototype of VDERM system has been implemented into a personal computer. The coder, voice-to-image converter, image database, and system interface are preinstalled in the personal computer. In this article, we present and discuss some evaluations that have been conducted in supporting this proposed prototype. The results have shown that both voice and image are important for people to correctly recognize emotion in telecommunications and the proposed solution can provide an alternative to videophone systems. The future works list some modifications that can be done to the proposed prototype in order to make it more practical for mobile applications.
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Razak, Aishah Abdul, Mohamad Izani Zainal Abidin, and Ryoichi Komiya. "Voice Driven Emotion Recognizer Mobile Phone." In Mobile Computing, 3511–28. IGI Global, 2009. http://dx.doi.org/10.4018/978-1-60566-054-7.ch256.
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This article proposes an application of emotion recognizer system in telecommunications entitled voice driven emotion recognizer mobile phone (VDERM). The design implements a voice-to-image conversion scheme through a voice-to-image converter that extracts emotion features in the voice; recognizes them; and selects the corresponding facial expression images from image bank. Since it only requires audio transmission; it can support video communication at a much lower bit rate than the conventional videophone. The first prototype of VDERM system has been implemented into a personal computer. The coder; voice-to-image converter; image database; and system interface are preinstalled in the personal computer. In this article; we present and discuss some evaluations that have been conducted in supporting this proposed prototype. The results have shown that both voice and image are important for people to correctly recognize emotion in telecommunications and the proposed solution can provide an alternative to videophone systems. The future works list some modifications that can be done to the proposed prototype in order to make it more practical for mobile applications.
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Milhé, C. "Determination by 1H NMR of a Slow Conformational Transition and Hydration Change in the Consensus TATAAT Prsbnow Box." In Biological NMR Spectroscopy. Oxford University Press, 1997. http://dx.doi.org/10.1093/oso/9780195094688.003.0027.
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The conformational dynamics and hydration of a DNA 14-mer containing the consensus Pribnow box sequence TATAAT have been measured using rotating frame T1 measurements and NOESY and ROESY in water. The H2 proton resonances of adenines show fast intermediate exchange behavior which can be attributed to a conformational transition that affects the distances between H2 protons of neighboring adenine residues, both sequential and cross-strand. The relaxation rate constant of the transition was measured at 4000s-1 at 25°C. Bound water close to the H2 proton of adenines was observed with residence times of >lns. At low temperature (5°C), the Pribnow box is in a closed state in which hydration water in the minor groove is tightly bound. At higher temperatures, the conformation opens up as judged by the increase in separation between sequential H2 protons of adenines and water exchanges freely from the minor groove. The conformational transition and the altered hydration pattern may be related to promoter function. The control of gene expression in procaryotes depends on the specific recognition by RNA polymerase of a six base-pair sequence (consensus: TTGACA) located at -35 from the transcription site, and a second one, named the Pribnow box (consensus: TATAAT) at about 10 base-pairs upstream the initiation site (Rosenberg and Court, 1979). It has been shown (Hawley and McClure, 1983) that strong promoters exhibit a high degree of homology with the consensus sequences, separated by an optimum consensus spacer length of 17 base pairs. The strength of a promoter depends on, among other thing, the rate of the initiation of transcription. This rate depends on the product between the thermodynamic and kinetic constants KB and k2 (McClure, 1980). The initial binding of RNA polymerase to the promoter results in the formation of a transcriptionally inactive ‘closed’ complex, characterized by the association constant KB. Isomerization to the active ‘open’ complex then occurs, and is characterized by the first order rate constant k2. Hence, the frequency of transcription initiation depends both on the strength of the polymerase-promoter interaction, and the ease with which this complex can isomerize to the productive state. Both of these events are likely to depend on the physical properties of the promoter.
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Epstein, Irving R., and John A. Pojman. "Delays and Differential Delay Equations." In An Introduction to Nonlinear Chemical Dynamics. Oxford University Press, 1998. http://dx.doi.org/10.1093/oso/9780195096705.003.0016.
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Mathematically speaking, the most important tools used by the chemical kineticist to study chemical reactions like the ones we have been considering are sets of coupled, first-order, ordinary differential equations that describe the changes in time of the concentrations of species in the system, that is, the rate laws derived from the Law of Mass Action. In order to obtain equations of this type, one must make a number of key assumptions, some of which are usually explicit, others more hidden. We have treated only isothermal systems, thereby obtaining polynomial rate laws instead of the transcendental expressions that would result if the temperature were taken as a variable, a step that would be necessary if we were to consider thermochemical oscillators (Gray and Scott, 1990), for example, combustion reactions at metal surfaces. What is perhaps less obvious is that our equations constitute an average over quantum mechanical microstates, allowing us to employ a relatively small number of bulk concentrations as our dependent variables, rather than having to keep track of the populations of different states that react at different rates. Our treatment ignores fluctuations, so that we may utilize deterministic equations rather than a stochastic or a master equation formulation (Gardiner, 1990). Whenever we employ ordinary differential equations, we are making the approximation that the medium is well mixed, with all species uniformly distributed; any spatial gradients (and we see in several other chapters that these can play a key role) require the inclusion of diffusion terms and the use of partial differential equations. All of these assumptions or approximations are well known, and in all cases chemists have more elaborate techniques at their disposal for treating these effects more exactly, should that be desirable. Another, less widely appreciated idealization in chemical kinetics is that phenomena take place instantaneously—that a change in [A] at time t generates a change in [B] time t and not at some later time t + τ. On a microscopic level, it is clear that this state of affairs cannot hold.
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Van de Peer, Stefanie. "Hala Alabdallah Yakoub: Documentary as Poetic Subjective Experience in Syria." In Negotiating Dissidence. Edinburgh University Press, 2017. http://dx.doi.org/10.3366/edinburgh/9780748696062.003.0008.
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Against all the odds, and within a highly restrictive production context, women have been and continue to be the most politically engaged filmmakers in Syria. While feature‐length fiction films by women are rare or non‐existent, documentary maker Halla Alabdallah is working across different genres with obvious degrees of resistance. Trained by Omar Amiralay (Syria’s foremost documentary maker), her style is singular and experimental in nature. Her first film, I am the One Who Brings Flowers to her Grave (2006) was the first documentary made by a woman in Syria. It is a lyrical portrait of solidarity between women across the ages that experiments with ‘representation’. In As if We Were Catching a Cobra (2012) she looks at the art of cartoon and other politically inspired art forms, in Egypt and Syria, immediately before the start of the revolution in Cairo. She uses documentary as a weapon, she says, because it is necessary to negotiate the oppression and taboos in order to find an avenue for self-expression and dissidence. Women’s identity struggle and self-expression are addressed directly in her films, and there is an immense trust in her global spectators’ ability to empathise, as vocal and aural communication methods are explicitly used to express dissent.
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Berne, P. F., and S. Doublié. "Molecular Biology for Structural Biology." In Crystallization of Nucleic Acids and Proteins. Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780199636792.003.0007.
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The number of published 3D structures has increased exponentially in the last decade and the resulting mass of structural data has contributed significantly to the understanding of mechanisms underlying the biology of living cells. However, these mechanisms are so complex that structural biologists face still greater challenges, such as the study of higher-order functional complexes. As an example, we can mention the protein complexes that assemble around activated growth factor receptors to allow the transduction of extracellular signals through the membrane and inside the cell (1). Because of their diverse intrinsic properties, proteins exhibit variable difficulty for structural biology studies. Before the rise of recombinant expression methods, only a minority of protein structures were determined, representing mainly favourable cases: proteins of high abundance in their natural source which could be purified and crystallized, in contrast to rare proteins that were often refractory to crystallization. The advent of methods for recombinant protein overexpression was a breakthrough in this area. It was followed by an increasing number of publications describing the crystallization of proteins, not under their native form, but in modified versions after sequence engineering. First we will consider the classical use of molecular biology applied to optimize the expression system for a recombinant protein for structural biology, without modification of its sequence. In the second part, we will deal with molecular biology procedures aimed at engineering the properties of a protein through sequence modifications in order to make its crystallization possible. In the last part we will give an example where molecular biology can help solve a crystallographic problem, namely that of phase determination by introducing anomalous scatterers (e.g. selenium atoms) into the protein of interest. Whenever extraction of a protein from its natural source appears unsuitable for structural studies, molecular biology resources can be brought in, initially aiming at choosing and setting up an appropriate expression system. This initial approach could involve comparing various expression hosts and vectors and deciding if the protein is to be produced as a fusion to facilitate its purification.
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Sinclair, Neil. "Practical Expressivist Strategies and Presumptive Arguments for Realism." In Practical Expressivism, 218–46. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198866107.003.0009.
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There are several general ‘domesticating’ strategies that quasi-realists can employ to vindicate the important features of moral practice. These include the ancestral strategy (which subsumes an expressivist account of the feature in question under a more general account that also applies to non-expressive discourses), the immanent strategy (which elucidates a role for the relevant feature within the first-order debates of the discourse), and the standards strategy (which understands the relevant feature in terms of standards governing the correct application of predicates). Furthermore, common objections to the quasi-realist project can be rebutted: it is not committed to vindicating ‘second-rate’ versions of the important features of moral practice, nor to a problematic revision of our philosophical understanding, nor to an unhappily disjunctive account of our discursive practices. These points also suffice to undermine many ‘presumptive’ arguments for moral realism (and descriptivism).
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Affam, Augustine Chioma, Ezerie Henry Ezechi, and Malay Chaudhuri. "Classical Fenton and Sequencing Batch Reactor Treatment of Pesticide Wastewater." In Handbook of Research on Resource Management for Pollution and Waste Treatment, 373–403. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-0369-0.ch016.
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This chapter examined Fenton and sequencing batch reactor (SBR) treatment of pesticide industrial wastewater. The optimum operating conditions for Fenton pretreatment of the pesticide wastewater were H2O2/COD molar ratio 3.0, H2O2/Fe2+ molar ratio 10, pH 3 and reaction time 60 min. The COD and TOC removal were 58.51 and 39.76%, respectively and biodegradability (BOD5/COD ratio) increased from 0.02 to ~ 0.30 after 60 min reaction time. The reaction followed pseudo-first order kinetics with a rate constant (k) of 0.0083 min−1. In the post-treatment by aerobic SBR, five different Fenton operating conditions were investigated and H2O2/COD molar ratio 3.0, H2O2/Fe2+ molar ratio 25, pH 3 and reaction time 60 min appeared to be the most significant (p < 0.05) operating conditions. The Fenton–SBR treatment at 12 hr HRT achieved COD, TOC and BOD5 removal efficiency of 96.7, 97.7 and 93.3%, respectively. The Fenton-SBR process was effective for the treatment of pesticide wastewater.
Conference papers on the topic "Pseudo-first order rate expression"
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Ervin, J. S., and S. P. Heneghan. "The Meaning of Activation Energy and Reaction Order in Autoaccelerating Systems." In ASME 1997 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/97-gt-224.
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Global reaction mechanisms and rate constants are commonly used in computational fluid dynamics models which incorporate chemical reactions to study aviation fuel thermal and oxidative thermal stability. Often these models are calibrated using one set of conditions, such as flow rate and temperature. New conditions are then calculated by extrapolation using the global expressions. A close inspection of the origin of global oxidation rate constants reveals that in systems that undergo autocatalysis or auto inhibition, a simple over-all global activation energy and reaction order are not good descriptors of the reaction process. Furthermore, pseudo-detailed chemical kinetic modeling of a fuel which experiences autocatalysis shows that the observed reaction order for oxygen consumption varies with initial oxygen concentration, extent of reaction, and temperature. Thus, a simple global rate expression used to describe oxygen consumption in an autoaccelerating system is insufficient to allow extrapolation to different temperature or time regimes.
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Sagrilo, Luis Volnei Sudati, Fernando Jorge Mendes de Sousa, José Antonio Vargas Bazán, Zhen Gao, and Arvid Naess. "Long-Term Extreme Response of Marine Structures Considering the Combination of First and Second Order Wave Effects." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-11127.
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In this paper, the long-term extreme response of a floating marine structure subjected to first and second order (slow-drift) wave effects is addressed. The proposed formulation is based on the long-term up-crossing rate, which is obtained by integrating the contribution of all short-term sea states. In order to speed up the evaluation of the long-term integral, an analytical expression for the short-term responses up-crossing rates was adopted. This expression is based on Hermite polynomials, and considers the response as a second order Volterra stochastic process. This formulation was applied to evaluate the 1-yr, 10-yr and 100-yr lateral motions of a circular-shaped monocolumn platform, and the non-Gaussian (nonlinear) results are compared with those obtained by assuming the response as a Gaussian process.
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Naess, A., and H. C. Karlsen. "Nonlinear, Second-Order Response Statistics of Compliant Offshore Structures." In ASME 2003 22nd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2003. http://dx.doi.org/10.1115/omae2003-37127.
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The paper continues previous work to develop a new method for calculating the mean level crossing rate of a stochastic process represented as a second order stochastic Volterra series. The derivation of this procedure consists of three stages. First the expression for the mean crossing rate is rewritten in terms of a joint characteristic function. Secondly, it is noted that a closed form expression for this joint characteristic function can be derived. Thirdly, it is then demonstrated how the method of steepest descent can be applied to the numerical calculation of the mean crossing rate. It is shown by an example that the numerical accuracy of this method is apparently very high.
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Janna, William S., and John I. Hochstein. "A “Boundary Layer” Method of Obtaining an Approximate Solution to the Infinite Fin Problem." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-33626.
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The classical infinite fin problem is considered in this study. First the exact solution is stated in which temperature, heat transfer rate, effectiveness and fin efficiency are all given. Then the boundary layer method is used to obtain alternative solutions in polynomial form. Boundary conditions are written for this method, and applied in various combinations to an assumed temperature profile. First, second, and third order approximate solutions are derived. Temperature profiles obtained from these solutions are compared to that calculated from the exact solution. It is shown that as more terms are included in the assumed profile, the resultant expression better fits the exact solution. Very good agreement between the third order and exact solution was obtained. Also derived from the approximate solutions was a distance along the fin beyond which the temperature difference between the fin and the surroundings is negligible. This arbitrary distance is analogous to the boundary layer thickness for boundary layer flow over a flat plate.
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Lee, Jinwook, Choon S. Tan, Borislav T. Sirakov, Chris Wilkins, Hong-Sik Im, Martin Babak, and Denis Tisserant. "Performance Metric for Turbine Stage Under Unsteady Pulsating Flow Environment." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-56343.
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In a turbine stage for a vehicular turbocharger or a PDE (Pulse Detonation Engine) system, the power extraction process is inherently unsteady due to a highly pulsating flow delivered from the upstream combustor. Characterizing the operating performance of such a turbine stage would call for defining unsteady efficiency on a physically rigorous basis. Since the instantaneous efficiency can be calculated as the fraction of the actual power to the unsteady ideal power, an expression for the unsteady ideal power from the turbine stage is first derived by applying mass conservation and the First/Second Law of thermodynamics for the turbine stage. The newly derived expression elucidates the distinction from the quasi-steady situation in that the storage effect of mass/energy/entropy over the turbine stage is no longer negligible compared to the flux of mass/energy/entropy at the inlet and outlet. The storage effect resolves the previously reported physical inconsistency that the instantaneous efficiency can be a value of above unity or below zero; an erroneous result associated with defining the efficiency based on a quasi-steady basis. As the reduced frequency of the inlet pulsation of the turbine stage becomes larger than unity, the mass/energy/entropy accumulation rate over the turbine stage becomes significant compared to the mass/energy/entropy influx rate. Then, the definition of the efficiency based on a quasi-steady assumption loses its applicability. In this paper, the role of mass/energy/entropy storage rate in the unsteady ideal power is assessed in order to underpin the inconsistency in the previous quasi-steady approach. The utility of the unsteady efficiency definition is elucidated for the case of a turbocharger turbine stage subjected to high inlet flow pulsation.
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Buchanan, Cara F., Elizabeth Voigt, Pavlos P. Vlachos, and Marissa Nichole Rylander. "Tissue Engineered Tumor Microvessels to Study the Role of Flow Shear Stress on Endothelial Barrier Function." In ASME 2013 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/sbc2013-14592.
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As solid tumors develop, a variety of physical stresses arise including growth induced compressive force, matrix stiffening due to desmoplasia, and increased interstitial fluid pressure and altered flow patterns due to leaky vasculature and poor lymphatic drainage [1]. These microenvironmental stresses likely contribute to the abnormal cell behavior that drives tumor progression, and have become an increasingly significant area of cancer research. Of particular importance, is the role of flow shear stress on tumor-endothelial signaling, vascular function, and angiogenesis. Compared to normal vasculature, blood vessels in tumors are poorly functional due to dysregulated expression of angiogenic growth factors, such as vascular endothelial growth factor (VEGF) or the angiopoietins. Also, because of the abnormal vessel structure, blood velocities can be an order of magnitude lower than that of normal microvessels. Recently published work utilizing intravital microscopy to measure blood velocities in mouse mammary fat pad tumors, demonstrated for the first time that shear rate gradients in tumors may help guide branching and growth of new vessels [2]. However, much still remains unknown about how shear stress regulates endothelial organization, permeability, or expression of growth factors within the context of the tumor microenvironment.
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Khalid, Muhammad, Chenn Zhou, Ashish Bassi, San Ming Wang, Howard Gerber, and Charles Tseng. "Heat Transfer Analysis of Human Cell Culture Under RF Exposure." In ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems. ASMEDC, 2005. http://dx.doi.org/10.1115/ht2005-72655.
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A 2.45 GHz radio frequency (RF) exposure system was designed and used to study the RF effects on the genome-wide gene expression in cultured human cells. In this system, a T-25 culture flask, which contains 10 × 106 cells in a 10ml medium, is placed in a WR 340 waveguide. The waveguide serves as an environmental chamber. The source is a pulsed magnetron for obtaining a high electric field with the specific absorption rate (SAR) at approximately 10 W/kg. In order to ensure the non-thermal effect, the system was designed to maintain a temperature of 37°C. In this research, the heat transfer analysis of the system was conducted using the computational fluid dynamic (CFD) software FLUENT® coupled with the finite element software, High Frequency Structural Simulation (HFSS) by Ansoft. The electric field was first analyzed by using HFSS to calculate the SAR distribution as a heat source input for CFD calculations. The fluid flow and temperature distributions within the flask were then analyzed using FLUENT®. The results were validated experimentally by measuring the temperatures with fluoroptic thermometer probes as well as by examining the level of heat shock gene expression. These results provide useful information for a better understanding and controlling of the operating conditions of the system.
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Armitage, C. A., R. S. Cant, A. P. Dowling, and T. P. Hynes. "Linearised Theory for LPP Combustion Dynamics." In ASME Turbo Expo 2003, collocated with the 2003 International Joint Power Generation Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/gt2003-38670.
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Gas turbines which are operated under lean, premixed, pre–vaporised (LPP) conditions are notoriously susceptible to self–excited oscillations. In the combustion chamber the unsteady heat released by combustion processes interacts with pressure fluctuations. The challenge is to develop a tool which can determine the frequency and stability characteristics of self–excited oscillations in realistic gas–turbine geometries. To this end, the flow through the gas turbine is described as far as possible by taking advantage of linearised theory and analytical models of the behaviour in the combustion chamber. First, a steady, mean flow solution for an idealised axi–symmetric combustor geometry is calculated using the inviscid Euler equations for continuity, momentum and energy with a specified distributed mean heat release. Superimposed on this is a linearised, three–dimensional perturbed flow in which the time and circumferential variation are described by a complex frequency and mode number respectively. Within this numerical model of the combustor a ‘flame model’ is used to describe the change in the rate of combustion due to inlet flow perturbations. The flame model may be given by an analytical expression—for example using a simple time lag with an expression proportional to the mean heat release in order to describe the unsteady heat release. An alternative approach would be to use a localised and detailed unsteady CFD calculation to determine the flow downstream of a generic premix duct geometry. If the flow is perturbed at the inlet a relationship between these fluctuations and the unsteady heat release may be obtained. In order to capture the response of the system to a wide frequency range an appropriately chosen broad–band forcing function may be used to perturb the flow. System identification techniques allow the transfer function to be extracted and a suitable flame model for the linearised Euler calculations may be constructed. Sample calculations of each aspect of the research will be presented to demonstrate the capabilities of each technique and the viability of combining the approaches towards the goal of aiding the design of gas–turbine combustors. Calculations using the linearised Euler methodology with analytical expressions for the flame model will demonstrate the capability of the approach to identify the frequencies of oscillation, mode shapes and zones of stability of particular combustor geometries.
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Youssef, Sawsen, Olivier Calonne, and Hédi Hamdi. "Influence of Hand Disc Grinding on Surface Integrity of Nickel-Based Alloys: Numerical Approach." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97974.
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For complex part geometry, hand grinding is one of finishing and super finishing process the most used in mechanical industry. Surface integrity is today one major concern for industrials. The surface integrity is defined by a set of important characteristics of ground surface as surface geometric parameters (roughness, …), mechanical behaviour of the subsurface (hardness, residual stress, …) and structural changes of the material in the near surface. High heat and pressure, high strain and strain rate observed during hand grinding process, strongly influence surface integrity. Therefore, the surface behaviour, in terms of resistance to corrosion and crack initiation depends on how the process was conducted. The purpose of this study is to understand the effects of thermal and mechanical plastic deformation induced on the surface of components. The action of the disc-grinding wheel on the workpiece is modelled by a moving heat flux on the surface. The challenge is to be able to find the shape and intensity of thermomechanical load entering the workpiece in accordance with the hand disc grinding process and taking into account specific parameters of the process. In a first part, a mechanical description of the action of the disc-wheel on the surface is proposed in order to develop an analytic formulation of the grinding power and the heat flux density. They are function of the disc-grinding wheel velocity, the feed speed and the applied forces. This expression is then used in a finite element modelling to perform thermomechanical simulations of the hand disc-grinding process. In a first stage, heating and cooling are computed. They give maximum temperature reached, temperature gradients and cooling kinematic. In a second stage, thermomechanical computation is conducted in order to compute residual stresses induced by this abrasion process. A discussion based on experimental results obtained by XRD method is then proposed and some local explanation are given on the way the material structure has changed leading to a structural hardening in the 50 first microns beneath the ground surface.
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Depcik, Christopher, Sudarshan Loya, and Anand Srinivasan. "Adaptive Carbon Monoxide Kinetics for Exhaust Aftertreatment Modeling." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11173.
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Future emission standards are driving the need for advanced control of both Spark (SI) and Compression Ignition (CI) engines. However, even with the implementation of cooled Exhaust Gas Recirculation and Low Temperature Combustion (LTC), it is unlikely that in-cylinder combustion strategies alone will reduce emissions to levels below the proposed standards. As a result, researchers are developing complex catalytic aftertreatment systems to meet these tailpipe regulations for both conventional and alternative combustion regimes. Simulating these exhaust systems requires fast and accurate models suitable for significant changes in inlet conditions. Most aftertreatment devices contain Platinum Group Metals because of their widely documented beneficial catalysis properties; examples include Diesel Oxidation Catalysts, Three-Way Catalysts and Lean NOx Traps. There are kinetic mechanisms available for each of these devices, but often they do not extrapolate well to other formulations. For example, Carbon Monoxide (CO) levels entering a catalyst are significantly different between an SI and CI engine. In addition, modifying engine control to utilize LTC operation can result in an increase in CO levels due to lower combustion efficiency. This adversely affects the conversion capabilities of a catalytic device through increased levels of CO inhibition. Finally, catalyst loading and metal dispersion differences between devices often prohibit a direct extension of kinetic constants. As a result, mechanisms often need recalibration for correct modeling capabilities. In order to begin creating a more predictive kinetic mechanism, this paper simulates CO oxidation as a function of different inlet concentration levels and metal loadings. While aftertreatment devices contain many reactions, modeling of one fundamental reaction is a first step to determine the feasibility of adaptive kinetics. In addition, research into the history of the CO oxidation mechanism over platinum illustrates a more accurate rate expression to utilize in deference to current modeling activities. The authors calibrate this expression to experimental data taking into account significant changes in inlet conditions, metal loading and dispersion values. Model fidelity is determined through the simulation of additional data not part of the initial calibration efforts. In addition, the paper discusses strengths and weaknesses of the model along with how other researchers can help foster adaptive kinetic development.