Detailed Numerical and Experimental Investigation of Non-Isothermal Sintering of Amorphous Polymer Material

2002 ◽  
Vol 124 (3) ◽  
pp. 553-563 ◽  
Author(s):  
R. M. Tarafdar ◽  
T. L. Bergman
Keyword(s):  
Experimental Investigation ◽  
Numerical Model ◽  
Penetration Depth ◽  
Polymer Material ◽  
Amorphous Polymer ◽  
Experimental Results ◽  
Additional Insight ◽  
Morphological Response ◽  
Thermal Penetration Depth ◽  
Insight Into

Simulations and experiments are performed to investigate the coupled thermal and morphological response of polymer material during non-isothermal sintering. The experimental results are utilized to validate a numerical model that describes the response of the system. Predictions of the material expansion, its subsequent contraction due to sintering, and the temperature evolution are obtained and favorably compared with experimental results. Parametric simulations are performed to acquire additional insight into the dynamics of non-isothermal sintering while a relationship is established to describe the ratio of the sintering penetration depth to the thermal penetration depth and its dependence upon the boundary and initial temperatures.

Airflow-Housing-Induced Resonances of Rotating Optical Disks

2007 ◽  
Vol 74 (6) ◽  
pp. 1252-1263 ◽  
Author(s):  
R. M. C. Mestrom ◽  
R. H. B. Fey ◽  
H. Nijmeijer ◽  
P. M. R. Wortelboer ◽  
W. Aerts
Keyword(s):  
Numerical Model ◽  
Pressure Distribution ◽  
Critical Speed ◽  
Experimental Approach ◽  
Experimental Results ◽  
Lubrication Equation ◽  
Global View ◽  
Optical Disks ◽  
Insight Into ◽  
Finite Difference Techniques

Numerous excitation sources for disk vibrations are present in optical drives. For increasing rotation speeds, airflow-housing-induced vibrations have become more and more important. Currently, drives are designed in which rotation speeds are so high that critical speed resonances may show up. The presence of these resonances depends on the layout of the inner housing geometry of the drive. The influence of the drive inner housing geometry is investigated systematically by means of a numerical-experimental approach. An analytical model is derived, containing disk dynamics and the geometry-induced pressure distribution acting as the excitation mechanism on the disk. The Reynolds’ lubrication equation is used as a first approach for the modeling of the pressure distribution. The model is numerically implemented using an approach based on a combination of finite element and finite difference techniques. An idealized, drive-like environment serves as the experimental setup. This setup resembles the situation in the numerical model, in order to be able to verify the numerical model. Wedge-like airflow disturbances are used in order to obtain insight into the influence of drive inner geometry on the critical speed resonances of optical disks. A disk tilt measurement method is designed that yields a global view of the disk deformation. By means of two newly proposed types of plots, numerical and experimental results can be compared in a straightforward way. A qualitative match between the numerical and experimental results is obtained. The numerical and experimental methods presented provide insight into airflow-housing-induced vibrations in optical drives. Additionally, reduction of some critical speed resonances is found to be possible for certain drive inner geometry configurations.

Numerical and Experimental Investigation of Thermodynamic Behavior of Positive Displacement Compressor

2010 ◽  
Author(s):  
Morad Paknezhad ◽  
Tooraj Yousefi ◽  
Sajjad Sadeghi ◽  
Mehran Ahmadi
Keyword(s):  
Experimental Investigation ◽  
Numerical Model ◽  
Angular Velocity ◽  
Thermodynamic Analysis ◽  
Experimental Results ◽  
Thermodynamic Behavior ◽  
Outlet Pressure ◽  
Positive Displacement ◽  
Fluent Software ◽  
Good Agreement

A numerical model, based on dynamic mesh, has been developed by FLUENT software, to simulate behavior of a positive displacement compressor. Only first compression stage of compressor was modeled. Modeling was done, by dividing the domain to three areas with different type meshes. Some relations were presented for volumetric, mechanical, isothermal, and overall isothermal performance, and thermodynamic analysis has been performed in term of these relations. Effects of outlet pressure and crankshaft’s angular velocity have been investigated on work, polytropic factor of compression, and efficiency. Numerical and experimental results have been compared, and a good agreement was seen between them.

Effect of Nanoparticles on Forming Process of Bubbles in a Nanofluid

2009 ◽  
Author(s):  
Fengmin Su ◽  
Xuehu Ma ◽  
Jiabin Chen
Keyword(s):  
Experimental Investigation ◽  
High Speed ◽  
Ccd Camera ◽  
Experimental Results ◽  
Forming Process ◽  
Three Phase ◽  
Insight Into

An experimental investigation was conducted to determine the effect of nanoparticles on the forming process of bubbles in the gas-liquid-nanoparticle three-phase fluidization. In the experiment, a SiO2-water nanofluid was prepared without any surfactants, and the forming process of bubbles in the nanofluid was observed by the high-speed CCD camera. The experimental results show that the diameter of the formed bubble in the nanofluid is smaller 5% than that in water, and the frequency forming bubbles in the nanofluid is higher than that in water. The investigation can provide an insight into the functionary mechanism of the bubble forming process in the gas-liquid-nanoparticles nanofluids.

Classification of Infant Vocalizations by Untrained Listeners

2019 ◽  
Vol 62 (9) ◽  
pp. 3265-3275
Author(s):  
Heather L. Ramsdell-Hudock ◽  
Anne S. Warlaumont ◽  
Lindsey E. Foss ◽  
Candice Perry
Keyword(s):  
Formal Education ◽  
Additional Insight ◽  
Listener Responses ◽  
Infant Vocalization ◽  
Early Infant ◽  
Infant Vocalizations ◽  
Audio Recordings ◽  
Speech And Language Development ◽  
Insight Into

Purpose To better enable communication among researchers, clinicians, and caregivers, we aimed to assess how untrained listeners classify early infant vocalization types in comparison to terms currently used by researchers and clinicians. Method Listeners were caregivers with no prior formal education in speech and language development. A 1st group of listeners reported on clinician/researcher-classified vowel, squeal, growl, raspberry, whisper, laugh, and cry vocalizations obtained from archived video/audio recordings of 10 infants from 4 through 12 months of age. A list of commonly used terms was generated based on listener responses and the standard research terminology. A 2nd group of listeners was presented with the same vocalizations and asked to select terms from the list that they thought best described the sounds. Results Classifications of the vocalizations by listeners largely overlapped with published categorical descriptors and yielded additional insight into alternate terms commonly used. The biggest discrepancies were found for the vowel category. Conclusion Prior research has shown that caregivers are accurate in identifying canonical babbling, a major prelinguistic vocalization milestone occurring at about 6–7 months of age. This indicates that caregivers are also well attuned to even earlier emerging vocalization types. This supports the value of continuing basic and clinical research on the vocal types infants produce in the 1st months of life and on their potential diagnostic utility, and may also help improve communication between speech-language pathologists and families.

Diversity, Rationality, and the Division of Cognitive Labor

2017 ◽  
Author(s):  
Ryan Muldoon
Keyword(s):  
Social Structure ◽  
Division Of Labor ◽  
Additional Insight ◽  
Division Of Cognitive Labor ◽  
Social Structure Of Science ◽  
The Social ◽  
Insight Into

Existing models of the division of cognitive labor in science assume that scientists have a particular problem they want to solve and can choose between different approaches to solving the problem. In this essay I invert the approach, supposing that scientists have fixed skills and seek problems to solve. This allows for a better explanation of increasing rates of cooperation in science, as well as flows of scientists between fields of inquiry. By increasing the realism of the model, we gain additional insight into the social structure of science and gain the ability to ask new questions about the optimal division of labor.

scholarly journals Using syndromic measures of mortality to capture the dynamics of COVID-19 in Java, Indonesia, in the context of vaccination rollout

BMC Medicine ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Bimandra A. Djaafara ◽  
Charles Whittaker ◽  
Oliver J. Watson ◽  
Robert Verity ◽  
Nicholas F. Brazeau ◽  
...  
Keyword(s):  
Rural Areas ◽  
Vaccination Campaign ◽  
Control Measures ◽  
Additional Insight ◽  
Short Term ◽  
If Current ◽  
Vaccine Impact ◽  
Potential Impact ◽  
The Impact ◽  
Insight Into

Abstract Background As in many countries, quantifying COVID-19 spread in Indonesia remains challenging due to testing limitations. In Java, non-pharmaceutical interventions (NPIs) were implemented throughout 2020. However, as a vaccination campaign launches, cases and deaths are rising across the island. Methods We used modelling to explore the extent to which data on burials in Jakarta using strict COVID-19 protocols (C19P) provide additional insight into the transmissibility of the disease, epidemic trajectory, and the impact of NPIs. We assess how implementation of NPIs in early 2021 will shape the epidemic during the period of likely vaccine rollout. Results C19P burial data in Jakarta suggest a death toll approximately 3.3 times higher than reported. Transmission estimates using these data suggest earlier, larger, and more sustained impact of NPIs. Measures to reduce sub-national spread, particularly during Ramadan, substantially mitigated spread to more vulnerable rural areas. Given current trajectory, daily cases and deaths are likely to increase in most regions as the vaccine is rolled out. Transmission may peak in early 2021 in Jakarta if current levels of control are maintained. However, relaxation of control measures is likely to lead to a subsequent resurgence in the absence of an effective vaccination campaign. Conclusions Syndromic measures of mortality provide a more complete picture of COVID-19 severity upon which to base decision-making. The high potential impact of the vaccine in Java is attributable to reductions in transmission to date and dependent on these being maintained. Increases in control in the relatively short-term will likely yield large, synergistic increases in vaccine impact.

scholarly journals Thermochemical Heat Storage in a Lab-Scale Indirectly Operated CaO/Ca(OH)2 Reactor—Numerical Modeling and Model Validation through Inverse Parameter Estimation

2021 ◽  
Vol 11 (2) ◽  
pp. 682
Author(s):  
Gabriele Seitz ◽  
Farid Mohammadi ◽  
Holger Class
Keyword(s):  
Numerical Model ◽  
Gas Flow ◽  
Reaction Rate ◽  
Heat Storage ◽  
Bulk Material ◽  
Fixed Bed ◽  
Experimental Results ◽  
Fixed Bed Reactor ◽  
Thermochemical Heat Storage ◽  
Speed Up

Calcium oxide/Calcium hydroxide can be utilized as a reaction system for thermochemical heat storage. It features a high storage capacity, is cheap, and does not involve major environmental concerns. Operationally, different fixed-bed reactor concepts can be distinguished; direct reactor are characterized by gas flow through the reactive bulk material, while in indirect reactors, the heat-carrying gas flow is separated from the bulk material. This study puts a focus on the indirectly operated fixed-bed reactor setup. The fluxes of the reaction fluid and the heat-carrying flow are decoupled in order to overcome limitations due to heat conduction in the reactive bulk material. The fixed bed represents a porous medium where Darcy-type flow conditions can be assumed. Here, a numerical model for such a reactor concept is presented, which has been implemented in the software DuMux. An attempt to calibrate and validate it with experimental results from the literature is discussed in detail. This allows for the identification of a deficient insulation of the experimental setup. Accordingly, heat-loss mechanisms are included in the model. However, it can be shown that heat losses alone are not sufficient to explain the experimental results. It is evident that another effect plays a role here. Using Bayesian inference, this effect is identified as the reaction rate decreasing with progressing conversion of reactive material. The calibrated model reveals that more heat is lost over the reactor surface than transported in the heat transfer channel, which causes a considerable speed-up of the discharge reaction. An observed deceleration of the reaction rate at progressed conversion is attributed to the presence of agglomerates of the bulk material in the fixed bed. This retardation is represented phenomenologically by mofifying the reaction kinetics. After the calibration, the model is validated with a second set of experimental results. To speed up the calculations for the calibration, the numerical model is replaced by a surrogate model based on Polynomial Chaos Expansion and Principal Component Analysis.

scholarly journals Loss of RET Promotes Mesenchymal Identity in Neuroblastoma Cells

Cancers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1909
Author(s):  
Joachim T. Siaw ◽  
Jonatan L. Gabre ◽  
Ezgi Uçkun ◽  
Marc Vigny ◽  
Wancun Zhang ◽  
...  
Keyword(s):  
Genome Engineering ◽  
Neuroblastoma Cells ◽  
Gene Signature ◽  
Additional Insight ◽  
Downstream Target ◽  
Anaplastic Lymphoma ◽  
Extracellular Matrix Components ◽  
Transforming Gene ◽  
Insight Into

Aberrant activation of anaplastic lymphoma kinase (ALK) drives neuroblastoma (NB). Previous work identified the RET receptor tyrosine kinase (RTK) as a downstream target of ALK activity in NB models. We show here that ALK activation in response to ALKAL2 ligand results in the rapid phosphorylation of RET in NB cells, providing additional insight into the contribution of RET to the ALK-driven gene signature in NB. To further address the role of RET in NB, RET knockout (KO) SK-N-AS cells were generated by CRISPR/Cas9 genome engineering. Gene expression analysis of RET KO NB cells identified a reprogramming of NB cells to a mesenchymal (MES) phenotype that was characterized by increased migration and upregulation of the AXL and MNNG HOS transforming gene (MET) RTKs, as well as integrins and extracellular matrix components. Strikingly, the upregulation of AXL in the absence of RET reflects the development timeline observed in the neural crest as progenitor cells undergo differentiation during embryonic development. Together, these findings suggest that a MES phenotype is promoted in mesenchymal NB cells in the absence of RET, reflective of a less differentiated developmental status.

scholarly journals Experimental study of the $ \gamma p \rightarrow K^{0}\Sigma^{+}$, $ \gamma n \rightarrow K^{0} \Lambda$, and $ \gamma n \rightarrow K^{0} \Sigma^{0}$ reactions at the Mainz Microtron

2019 ◽  
Vol 55 (11) ◽  
Author(s):  
C. S. Akondi ◽  
K. Bantawa ◽  
D. M. Manley ◽  
S. Abt ◽  
P. Achenbach ◽  
...  
Keyword(s):  
Experimental Study ◽  
Cross Sections ◽  
Differential Cross ◽  
Legendre Polynomials ◽  
Neutral Kaon ◽  
Experimental Results ◽  
Differential Cross Sections ◽  
Theoretical Predictions ◽  
Photoproduction Reactions ◽  
Insight Into

Abstract.This work measured $ \mathrm{d}\sigma/\mathrm{d}\Omega$dσ/dΩ for neutral kaon photoproduction reactions from threshold up to a c.m. energy of 1855MeV, focussing specifically on the $ \gamma p\rightarrow K^0\Sigma^+$γp→K0Σ+, $ \gamma n\rightarrow K^0\Lambda$γn→K0Λ, and $ \gamma n\rightarrow K^0 \Sigma^0$γn→K0Σ0 reactions. Our results for $ \gamma n\rightarrow K^0 \Sigma^0$γn→K0Σ0 are the first-ever measurements for that reaction. These data will provide insight into the properties of $ N^{\ast}$N* resonances and, in particular, will lead to an improved knowledge about those states that couple only weakly to the $ \pi N$πN channel. Integrated cross sections were extracted by fitting the differential cross sections for each reaction as a series of Legendre polynomials and our results are compared with prior experimental results and theoretical predictions.

Technology in Context: Mediating Factors in the Utilization of Planning Technologies

2005 ◽  
Vol 37 (5) ◽  
pp. 895-907 ◽  
Author(s):  
Ari Goelman
Keyword(s):  
Organizational Structure ◽  
Information Technologies ◽  
Public Access ◽  
Web Gis ◽  
Gis Technology ◽  
Additional Insight ◽  
Mediating Factors ◽  
The Impact ◽  
Insight Into

My research explores the question: how can theorists better understand the ways in which planning technologies are used by municipal planners? In the case-study municipality, a recently introduced web-GIS technology had little demonstrable success in attaining two of its stated goals: enabling increased public access to municipal geographic information and encouraging planners to produce their own maps. My research links these outcomes not only to the technologies themselves, but to organizational structure and human agency. Planners and planning theorists can gain additional insight into the impact of planning technologies through closer attention to the process through which planners come to use information technologies and the way this process both alters and is constrained by existing organizational constraints, including previously adopted technologies.

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