Modeling of Hardwood Pyrolysis Using the Convex Combination of the Mass Conversion Points

2019 ◽  
Vol 142 (6) ◽  
Author(s):  
Alok Dhaundiyal ◽  
Laszlo Toth
Keyword(s):  
Convex Combination ◽  
Initial Distribution ◽  
Mass Variation ◽  
Test Rig ◽  
Qualitative Aspect ◽  
Cross Sectional ◽  
Mass Conversion ◽  
Pyrolysis Reactor ◽  
Kinetics Of ◽  
Initial Distribution Function

Abstract This work investigates the kinetics of a pyrolysis reactor. Pyrolysis is demarcated as a two-step process that is the primary and the secondary decomposition of hardwood in the presence of nitrogen. The qualitative aspect of the analysis is performed by allowing the heterogeneous characteristics of the initial distribution function of volatile content. The temperature inside the reactor varies from 19 °C to 363.761 °C. The pressure of producer gas changes from 6 Pa to 26.8 Pa during the pyrolysis of hardwood, which affects the conversion of biomass with respect to temperature. The weighted fraction of the Weibull and the Rayleigh models is used for modeling the mass variation of the biomass inside the rector. The dimension of the reactor used for the experimental work has a length of 400 mm and a cross-sectional area of 9498.5 mm2. The pyrolysis test rig is programed for the cubical form of thermal history [T = (at3 + bt2 + ct − d)].

Investigation of irradiation-induced nucleation processes in silicon and germanium

1995 ◽  
Vol 53 ◽  
pp. 224-225
Author(s):  
Harry A. Atwater ◽  
C.M. Yang ◽  
K.V. Shcheglov
Keyword(s):  
Room Temperature ◽  
Crystal Size ◽  
Initial Distribution ◽  
Engineering Control ◽  
Size Evolution ◽  
Silicon And Germanium ◽  
Ge Quantum Dot ◽  
And Control ◽  
Germanium Quantum Dots ◽  
Kinetics Of

Studies of the initial stages of nucleation of silicon and germanium have yielded insights that point the way to achievement of engineering control over crystal size evolution at the nanometer scale. In addition to their importance in understanding fundamental issues in nucleation, these studies are relevant to efforts to (i) control the size distributions of silicon and germanium “quantum dots𠇍, which will in turn enable control of the optical properties of these materials, (ii) and control the kinetics of crystallization of amorphous silicon and germanium films on amorphous insulating substrates so as to, e.g., produce crystalline grains of essentially arbitrary size.Ge quantum dot nanocrystals with average sizes between 2 nm and 9 nm were formed by room temperature ion implantation into SiO2, followed by precipitation during thermal anneals at temperatures between 30°C and 1200°C[1]. Surprisingly, it was found that Ge nanocrystal nucleation occurs at room temperature as shown in Fig. 1, and that subsequent microstructural evolution occurred via coarsening of the initial distribution.

Oxidation Kinetics of Cu-Ni Alloy Observed by in situ UHV-TEM

2007 ◽  
Vol 1026 ◽  
Author(s):  
Li Sun ◽  
John E. Pearson ◽  
Judith C. Yang
Keyword(s):  
High Vacuum ◽  
Alloy Film ◽  
Ultra High Vacuum ◽  
Cross Sectional ◽  
Primary Mechanism ◽  
Transmission Electron ◽  
Ni Alloy ◽  
Cu Oxidation ◽  
Kinetics Of

AbstractThe nucleation and growth of Cu2O and NiO islands due to oxidation of Cu-24%Ni(001) films were monitored at various temperatures by in situ ultra-high vacuum (UHV) transmission electron microscopy (TEM). In remarkable contrast to our previous observations of Cu and Cu-Au oxidation, irregular-shaped polycrystalline oxide islands were observed to form with respect to the Cu-Ni alloy film, and an unusual second oxide nucleation stage was noted. Similar to Cu oxidation, the cross-sectional area growth rate of the oxide island is linear indicating oxygen surface diffusion is the primary mechanism of oxide growth.

omparisons of Silicide Formation by Rapid Thermal Annealing and Conventional Furnace Annealing

1987 ◽  
Vol 92 ◽  
Author(s):  
E. Ma ◽  
M. Natan ◽  
B.S. Lim ◽  
M-A. Nicolet
Keyword(s):  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Silicide Formation ◽  
X Ray Diffraction ◽  
Furnace Annealing ◽  
Cross Sectional ◽  
Conventional Furnace ◽  
Diffusion Controlled ◽  
Conventional Furnace Annealing ◽  
Kinetics Of

ABSTRACTSilicide formation induced by rapid thermal annealing (RTA) and conventional furnace annealing (CFA) in bilayers of sequentially deposited films of amorphous silicon and polycrystalline Co or Ni is studied with RBS, X-ray diffraction and TEM. Particular attention is paid to the reliability of the RTA temperature measurements in the study of the growth kinetics of the first interfacial compound, Co2Si and Ni2Si, for both RTA and CFA. It is found that the same diffusion-controlled kinetics applies for the silicide formation by RTA in argon and CFA in vacuum with a common activation energy of 2.1+0.2eV for Co2Si and 1.3+0.2eV for Ni Si. Co and Ni atoms are the dominant diffusing species; during silicide formation by both RTA and CFA. The microstructures of the Ni-silicide formed by the two annealing techniques, however, differs considerably from each other, as revealed by cross-sectional TEM studies.

scholarly journals Analytical solution of integro-differential equations describing the process of intense boiling of a superheated liquid

2021 ◽  
Author(s):  
Irina Alexandrova ◽  
Alexander Ivanov ◽  
Dmitri Alexandrov
Keyword(s):  
Distribution Function ◽  
Analytical Solution ◽  
Approximate Analytical Solution ◽  
Initial Distribution ◽  
Size Distribution Function ◽  
Superheated Liquid ◽  
Balance Equations ◽  
The Laplace Transform ◽  
And Shifts ◽  
Initial Distribution Function

In this article, an approximate analytical solution of an integro-differential system of equations is constructed, which describes the process of intense boiling of a superheated liquid. The kinetic and balance equations for the bubble-size distribution function and liquid temperature are solved analytically using the Laplace transform and saddle-point methods with allowance for an arbitrary dependence of the bubble growth rate on temperature. The rate of bubble appearance therewith is considered in accordance with the Dering-Volmer and Frenkel-Zeldovich-Kagan nucleation theories. It is shown that the initial distribution function decreases with increasing the dimensionless size of bubbles and shifts to their greater values with time.

Annealing of Amorphous Ni-Nb/Cu Overlayer Films - Thermal Groove Kinetics

1990 ◽  
Vol 181 ◽  
Author(s):  
S. N. Farrens ◽  
J. H. Perepczko
Keyword(s):  
Diffusion Processes ◽  
Effective Diffusion ◽  
Amorphous Film ◽  
Cross Sectional ◽  
Annealing Behavior ◽  
Cu Films ◽  
Cu Film ◽  
Sputter Deposited ◽  
Kinetics Of ◽  
Microstructural Examination

ABSTRACTRecent studies have shown that sputter deposited amorphous NixNb1−x (60≤×≤75) alloy films are effective diffusion barriers for operation at temperatures up to 6(X) °C[1]. The thermal stability of the amorphous films has been established on Si and GaAs substrates and may be modified by interactions wilji polycrystalline metal overlayer films. In the current work a detailed microstructural examination by cross-sectional TEM was performed on the annealing behavior of 50 nm polycrystalline Cu films on amorphous Ni60Nb40. Specifically, the development of grooves at the intersection of grain boundaries in the Cu film with both the free surface and the amorphous Ni60Nb40 base was monitored to evaluate the low temperature interfacial diffusion processes. Based upon measurements of the groove dimensions and dihedral angle during vacuum annealing at 450 °C, the surface diffusion coefficient of Cu was determined as 7.4 × 10-20 m2/sec and the surface energy for Cu derived from groove kinetics was in good agreement with other reported determinations. In addition, the grain boundary grooves that were present at the Cu/amorphous Ni60Nb40 interface in the as-deposited condition were observed to be eliminated during annealing. Again, by following the kinetics of groove healing the interfacial diffusivity was determined to be of the order of 10-28m2/sec at 500 °C and the interfacial energy for the amorphous film/Cu surface was estimated to be ≥ 340 mJ/cm2. The benefits of utilizing amorphous Ni-Nb alloys as underlays to retard thermal grooving and electromigration failure in copper arc discussed.

Cure kinetics of PF/PVAc hybrid adhesive for manufacturing profiled wood-strand composites

Holzforschung ◽  
2010 ◽  
Vol 64 (5) ◽  
Author(s):  
Yi Wang ◽  
Vikram Yadama ◽  
Marie-Pierre Laborie ◽  
Debes Bhattacharyya
Keyword(s):  
Hot Pressing ◽  
Phenol Formaldehyde ◽  
Cure Kinetics ◽  
Roll Forming ◽  
Good Prediction ◽  
Forming Process ◽  
Scanning Calorimetry ◽  
Cross Sectional ◽  
Kinetics Of ◽  
Wood Strand

Abstract In thermoforming of profiled wood-strand composites, an adhesive system is needed to provide a weak initial bond to maintain mat integrity and architecture during the forming process and eventually a durable bond when the final cross-sectional shape is achieved. A hybrid adhesive composed of phenol formaldehyde (PF) and poly(vinyl acetate) (PVAc) is proposed in this study. The cure kinetics of this hybrid adhesive and bond development in a multi-step hot-pressing is discussed. Cure kinetics studied by differential scanning calorimetry indicated that adding PVAc slowed down the curing reaction of PF resin; however, the full cure of PF was not inhibited. The nth-order Borchardt Daniels (nth-BD) model provided good prediction for the curing of adhesives with a PF/PVAc ratio lower than 1:1. To simulate roll forming of wood-strand mats, a hot-pressing schedule at low temperature combined with multi-stage closing and opening was developed. The nth-BD model was able to predict the actual bond development for composites made with neat PF resin. The results indicated that cure kinetics of a PF/PVAc hybrid adhesive would not significantly differ from neat PF resin for blend ratios of 1:1 or lower, thus potentially providing a resin system for roll forming or matched-die forming of wood-strand composites.

Growth kinetics of MgB2 layer and interfacial MgO layer during ex situ annealing of amorphous boron film

2004 ◽  
Vol 19 (10) ◽  
pp. 3081-3089 ◽  
Author(s):  
Hyun-Mi Kim ◽  
Sung-Soo Yim ◽  
Ki-Bum Kim ◽  
Seung-Hyun Moon ◽  
Young-Woon Kim ◽  
...  
Keyword(s):  
Growth Kinetics ◽  
Interfacial Layer ◽  
Surface Reaction ◽  
Layer Growth ◽  
Ex Situ ◽  
Amorphous Boron ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Kinetics Of ◽  
Rough Surface Morphology

This paper describes the growth kinetics of an interfacial MgO layer as well as those of an MgB2 layer during ex situ annealing of the evaporated amorphous boron (a-B) film under Mg vapor overpressure. A thin MgO layer is formed at the interface between a-B and Al2O3 substrate before the formation of crystalline MgB2 layer and the interfacial layer is epitaxially related with Al2O3 substrate (MgO (111)[110] // Al2O3 (0001)[1100]). The interfacial MgO layer continues to grow during the annealing, and its apparent growth rate is about 0.1 nm/min. The analysis of MgB2 layer growth kinetics using cross-sectional transmission electron microscopy reveals that there exist two distinct growth fronts at both sides of an MgB2 layer. The growth kinetics of the lower MgB2 layer obeys the parabolic rate law during the entire annealing time. The growth of the upper MgB2 layer is controlled by the surface reaction between out-diffused boron and Mg vapor up to 10 min, resulting in a rough surface morphology of MgB2 layer. By considering the mass balance of Mg and boron during ex situ annealing, we obtained the diffusivities of Mg and boron in MgB2 layer which were in the same order range of approximately 10−12 cm2/s.

scholarly journals Common morbidities and felt needs of salt pan workers in a coastal area of Tamil Nadu, India

2019 ◽  
Vol 7 (3) ◽  
pp. 805
Author(s):  
Jyothi Vasudevan ◽  
Saravanan Vaithiyalingam ◽  
Velavan Anandan ◽  
Amit Kumar Mishra ◽  
Anil J. Purty
Keyword(s):  
Working Conditions ◽  
Tamil Nadu ◽  
Cross Sectional Study ◽  
Health Problems ◽  
Work Place ◽  
Qualitative Aspect ◽  
Cross Sectional ◽  
Musculoskeletal Problems ◽  
Salt Pan ◽  
The Government

Background: The occupational hazards faced by salt pan workers during their occupation are myriad, a fact compounded by the lack of basic amenities at their workplace and lack of awareness regarding usage of personal protection equipment.Methods: This cross-sectional study was carried out among fifty-six salt pan workers in Marakkanam, Tamil Nadu to assess their common health problems and a qualitative component was added to assess their felt needs in work place and daily living. Data was collected using pre-designed data collection sheet for assessing the common morbidities. For the qualitative aspect of the study, in-depth interviews were conducted among twenty workers based on convenient sampling, using open ended questions. Data was collected after obtaining informed consent and steps were taken to ensure confidentiality at all stages.Results: The most common health problem of the workers in present study area included dental caries (41.7%), skin conditions (38.1%) musculoskeletal problems (36.7%) and anemia (35.1%) being other significant health problems. The qualitative aspect of the study revealed that the felt needs were improvement of their working conditions and more social support from the Government and the employers. There was very little awareness among the workers regarding use of PPE and none of them used any form of PPE.Conclusions: Salt pan workers had dental problems, dermatological problems and musculoskeletal problems as most common morbidities among them. Harsh working conditions, financial insecurity etc. are some of their work-related problems. Provision of housing facility and financial assistance during off- season by the government, basic amenities at the work place, paid leave in case of injuries, and insurance schemes for them by employer are their main felt needs. They also had no awareness regarding usage of personal protective equipment at the work place.

The kinetics of haemoglobin and ferritin in longitudinal community patients with iron deficiency or hypoxia

Diagnosis ◽  
2017 ◽  
Vol 4 (1) ◽  
pp. 35-41 ◽  
Author(s):  
Tony Badrick ◽  
Alice M. Richardson ◽  
Ashley Arnott ◽  
Brett A. Lidbury
Keyword(s):  
Laboratory Diagnosis ◽  
Random Structure ◽  
Cross Sectional ◽  
Distribution Width ◽  
Iron Deficient ◽  
Patient Groups ◽  
Significant Patterns ◽  
The Relationship ◽  
Kinetics Of ◽  
Community Patients

AbstractBackground:Red cell distribution width (RDW) is well recognised as a marker of iron-deficient anaemia, as well as useful to the distinction between some anaemic states. A role in the prediction of patient mortality and for the laboratory diagnosis of organ dysfunction has been also investigated. RDW has recently been suggested as a marker of acute and chronic hypoxia.Methods:In this paper we use RDW kinetics to identify different patient groups and then investigate the relationship between RDW, ferritin and haemoglobin kinetics in a large cross-sectional community patient dataset.Results:A novel mathematical model of this relationship is developed that captures all aspects of variation in the data. A linear regression of RDW/log(ferritin) on days is combined with a multi-level random structure including random intercepts and slopes for each patient.Conclusions:No evidence of an age affect was found in the data. On the other hand, significant patterns in the rises and falls of log(ferritin) and haemoglobin with RDW over time are identified.

scholarly journals Unaffected contractility of diaphragm muscle fibers in humans on mechanical ventilation

2014 ◽  
Vol 307 (6) ◽  
pp. L460-L470 ◽  
Author(s):  
Pleuni E. Hooijman ◽  
Marinus A. Paul ◽  
Ger J. M. Stienen ◽  
Albertus Beishuizen ◽  
Hieronymus W. H. Van Hees ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Muscle Fibers ◽  
Calcium Sensitivity ◽  
Diaphragm Muscle ◽  
Cross Sectional ◽  
Fast Twitch Muscle ◽  
Slow Twitch ◽  
Fast Twitch ◽  
Kinetics Of ◽  
Contractile Performance

Several studies have indicated that diaphragm dysfunction develops in patients on mechanical ventilation (MV). Here, we tested the hypothesis that the contractility of sarcomeres, i.e., the smallest contractile unit in muscle, is affected in humans on MV. To this end, we compared diaphragm muscle fibers of nine brain-dead organ donors (cases) that had been on MV for 26 ± 5 h with diaphragm muscle fibers from nine patients (controls) undergoing surgery for lung cancer that had been on MV for less than 2 h. In each diaphragm specimen we determined 1) muscle fiber cross-sectional area in cryosections by immunohistochemical methods and 2) the contractile performance of permeabilized single muscle fibers by means of maximum specific force, kinetics of cross-bridge cycling by rate of tension redevelopment, myosin heavy chain content and concentration, and calcium sensitivity of force of slow-twitch and fast-twitch muscle fibers. In case subjects, we noted no statistically significant decrease in outcomes compared with controls in slow-twitch or fast-twitch muscle fibers. These observations indicate that 26 h of MV of humans is not invariably associated with changes in the contractile performance of sarcomeres in the diaphragm.

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