A semi-empirical method for correlating the thermal performance of charring ablative materials

Author(s):  
S. MEZINES
Author(s):  
M. C. Wu ◽  
T. Y. Wu ◽  
J. T. Horng ◽  
S. F. Chang ◽  
P. L. Chen ◽  
...  

An effective semi-empirical method that combines thermal network models and empirical correlations for exploring the thermal performance of heat sinks and HS/TEC assemblies under different external thermal resistances is successfully established. A series of parametric studies, including the effects of external thermal resistance, input current of TEC and pumping heat capacity, on thermal performance improvements of HS/TEC assemblies have been performed. The Response Surface Methodology (RSM) is applied to establish explicit models of the thermal performance of HS/TEC assemblies under various external thermal resistances in terms of the design variables through statistical fitting method. Furthermore, the numerical optimization results for HS/TEC assemblies under different constraints are obtained. With constrained optimal designs of HS/TEC assemblies, the HS/TEC assemblies can provide excellent thermal performance improvements on (1) the reduction of thermal resistance, (2) the enhancement of module heat loads and (3) the improvement of external thermal resistance.


Author(s):  
M. C. Wu ◽  
C. H. Peng ◽  
C. Y. Lee ◽  
C. J. Fang ◽  
Y. H. Hung

The demand for high execution speed and memory capacity for modern computers results in an increasing circuit density per unit chip and high power dissipation per unit volume. Consequently, traditional air cooling technology such as air-cooled heat sink is reaching the limits for electronic applications. Thermoelectric coolers are regarded as potential solutions for enhancing the performance of air-cooled heat sinks. In the present study, a semi-empirical method for exploring the thermal performance of a heat sink integrated with or without TEC has been successfully established. A concept of design of experiments (DOE) is applied, and a statistical method for sensitivity analysis of the influencing parameters is performed to determine the key factors that are critical to the design. By the statistical sensitivity analysis of ANOVA F-test for the temperature reduction (ΔTC−B) and COP of the TEC, the factor contributions of QP, Rext and I are 31.66%, 33.73%, 34.61% as well as 14.9%, 0%, 85.1%, respectively. By employing the gradient-based numerical optimization technique, a series of constrained optimal designs have been performed. Under the given constraints of COP≧2, the optimal value of ΔTC−B (3.3°C) is obtained with the corresponding Qp (31.99W) and Qte (16W). Comparisons between the results by the present optimal design and those obtained by the semi-empirical results have been made with a satisfactory agreement. The present optimal design shows that a heat sink integrated with TEC can extend the upper limits of thermal management for traditional air-cooled heat sinks.


2020 ◽  
Author(s):  
Kenneth Lucas ◽  
George Barnes

We present the results of direct dynamics simulations and DFT calculations aimed at elucidating the effect of \textit{O}-sulfonation on the collision induced dissociation for serine. Towards this end, direct dynamics simulations of both serine and sulfoserine were performed at multiple collision energies and theoretical mass spectra obtained. Comparisons to experimental results are favorable for both systems. Peaks related to the sulfo group are identified and the reaction dynamics explored. In particular, three significant peaks (m\z 106, 88, and 81) seen in the theoretical mass spectrum directly related to the sulfo group are analyzed as well as major peaks shared by both systems. Our analysis shows that the m\z 106 peaks result from intramolecular rearrangements, intermolecular proton transfer among complexes composed of initial fragmentation products, and at high energy side-chain fragmentation. The \mz 88 peak was found to contain multiple constitutional isomers, including a previously unconsidered, low energy structure. It was also seen that the RM1 semi empirical method was not able to obtain all of the major peaks seen in experiment for sulfoserine. In contrast, PM6 did obtain all major experimental peaks.


2019 ◽  
Author(s):  
Chem Int

The full conformational space of N-formyl-L-alanine-amide was explored by the semi-empirical method AM1 coupled to the Multi Niche Crowding (MNC) genetic algorithm implemented in a package of programs developed in our laboratory. The structural and energy analysis of the resulting conformational space E(,ψ) exhibits 5 regions or minima ɣL, ɣD, ɛL, D and αD. The technique provides better detection of local and global minima within a reasonable time.


2021 ◽  
Vol 9 (5) ◽  
pp. 465
Author(s):  
Angelos Ikonomakis ◽  
Ulrik Dam Nielsen ◽  
Klaus Kähler Holst ◽  
Jesper Dietz ◽  
Roberto Galeazzi

This paper examines the statistical properties and the quality of the speed through water (STW) measurement based on data extracted from almost 200 container ships of Maersk Line’s fleet for 3 years of operation. The analysis uses high-frequency sensor data along with additional data sources derived from external providers. The interest of the study has its background in the accuracy of STW measurement as the most important parameter in the assessment of a ship’s performance analysis. The paper contains a thorough analysis of the measurements assumed to be related with the STW error, along with a descriptive decomposition of the main variables by sea region including sea state, vessel class, vessel IMO number and manufacturer of the speed-log installed in each ship. The paper suggests a semi-empirical method using a threshold to identify potential error in a ship’s STW measurement. The study revealed that the sea region is the most influential factor for the STW accuracy and that 26% of the ships of the dataset’s fleet warrant further investigation.


2020 ◽  
Vol 2 (7) ◽  
Author(s):  
Oluchukwu M. Okoh ◽  
Kazeem A. Lawal ◽  
Asekhame U. Yadua ◽  
Mathilda I. Ovuru ◽  
Stella I. Eyitayo ◽  
...  

1970 ◽  
Vol 2 (4) ◽  
pp. 865-874 ◽  
Author(s):  
I. V. Abarenkov ◽  
A. V. Amosov ◽  
V. F. Bratsev ◽  
D. M. Yudin

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