Estimating groundwater discharge to surface waters using heat as a tracer in low flux environments: the role of thermal conductivity

2015 ◽  
Vol 30 (3) ◽  
pp. 383-395 ◽  
Author(s):  
Carlos Duque ◽  
Sascha Müller ◽  
Eva Sebok ◽  
Kinza Haider ◽  
Peter Engesgaard
Keyword(s):  
Thermal Conductivity ◽  
Surface Waters ◽  
Groundwater Discharge ◽  
Heat As A Tracer

Lattice Thermal Conductivity Modelling of a Diatomic Nanoscale Material

2020 ◽  
Vol 10 (5) ◽  
pp. 602-609
Author(s):  
Adil H. Awad
Keyword(s):  
Thermal Conductivity ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Correction Term ◽  
Nanoscale Material ◽  
New Approach ◽  
Two Samples ◽  
Conductivity Modelling ◽  
Callaway Model

Introduction: A new approach for expressing the lattice thermal conductivity of diatomic nanoscale materials is developed. Methods: The lattice thermal conductivity of two samples of GaAs nanobeam at 4-100K is calculated on the basis of monatomic dispersion relation. Phonons are scattered by nanobeam boundaries, point defects and other phonons via normal and Umklapp processes. Methods: A comparative study of the results of the present analysis and those obtained using Callaway formula is performed. We clearly demonstrate the importance of the utilised scattering mechanisms in lattice thermal conductivity by addressing the separate role of the phonon scattering relaxation rate. The formulas derived from the correction term are also presented, and their difference from Callaway model is evident. Furthermore their percentage contribution is sufficiently small to be neglected in calculating lattice thermal conductivity. Conclusion: Our model is successfully used to correlate the predicted lattice thermal conductivity with that of the experimental observation.

Role of electron–phonon coupling in thermal conductivity of metallic nanofluids

2019 ◽  
Vol 52 (48) ◽  
pp. 485302 ◽  
Author(s):  
Dong-Xing Song ◽  
Yu-Feng Zhang ◽  
Wei-Gang Ma ◽  
Xing Zhang
Keyword(s):  
Thermal Conductivity ◽  
Phonon Coupling ◽  
Electron Phonon Coupling

Role of graphene waviness on the thermal conductivity of graphene composites

2012 ◽  
Vol 111 (1) ◽  
pp. 221-225 ◽  
Author(s):  
Ke Chu ◽  
Wen-sheng Li ◽  
Hongfeng Dong
Keyword(s):  
Thermal Conductivity

scholarly journals Relative importance of the bacteria Brucella, Salmonella, Staphylococcus and other indicator bacteria in some mountain farm waters in West-Cameroon (Central Africa) and the potential role of some environmental factors

2020 ◽  
Vol 8 (2) ◽  
pp. 081-084
Author(s):  
Pierrette Ngo Bahebeck ◽  
Mireille Ebiane Nougang ◽  
Paul Alain Nana ◽  
Claire Stéphane Metsopkeng ◽  
Antoine Tamsa Arfao ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Surface Waters ◽  
Brucella Abortus ◽  
Physicochemical Parameters ◽  
Potential Role ◽  
Abiotic Factors ◽  
Central Africa ◽  
Mountainous Regions ◽  
Brucella Suis

A bacteriological and physicochemical study was conducted in the waters of farms in mountainous regions of Cameroon. The different water samples were collected during two campaigns in December 2018 and February 2019. Ten stations representing the drinking water supply points in our study area were identified. The results showed that these waters contained both pathogenic and commensal fecal bacteria. The highest abundances reached 10x103 CFU/100mL for Salmonella sp., 72x103 CFU/100mL for Staphylococcus aureus, 102x103 CFU/100mL for Brucella suis and 40x103 CFU/100mL for Brucella abortus. These abundances were subject to space-time fluctuations. Water contamination by tweezers was not general and was present only in surface waters (rivers and ponds). The water in the ponds, rivers and wells analyzed were all basic, with low mineralization on average. The dissolved oxygen ranged from 37.5 to 70.6%, nitrate from 3.7 to 19.8 mg/L and iron from 0.01 to 3.5 mg/L. Most of the physicochemical parameters were relatively stable during the two campaigns. The degree of correlation between the physicochemical parameters and the abundance dynamics of the isolated bacteria was heterogeneous. This was clearly more pronounced with Salmonella sp. and Brucella suis. This would be due to the fraction of metabolically active cells present when the bacteria are exposed to unfavorable conditions. Correlations with the abiotic factors were less marked with Staphylococcus aureus and Brucella abortus; this would be due to their tolerance to environmental stresses.

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