FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W2945004535> ?p ?o ?g. }

• W2945004535 abstract "Author(s): Lubner, Sean | Advisor(s): Dames, Chris | Abstract: Creating technologies to address increasingly diverse challenges ranging from biomedical devices to carbon-free energy solutions requires measuring material properties and system behaviors in increasingly challenging regimes. In the biomedical field, accurate determination of the thermal conductivity (k) of biological tissues is important for cryopreservation, thermal ablation, and cryosurgery, but is hampered by the delicate nature and often-small sizes of tissues. In the electronics and clean energy fields, it is increasingly necessary to reliably model the dissipation of heat from micro and nanoelectronics for thermal management, and the transport of heat through nanostructured materials for energy control and conversion technologies such as batteries and thermoelectrics. However, the classical equations of heat transfer break down at these short length scales, calling into question the validity of various formulations of heat transfer theory and the very concept of thermal conductivity itself. Here, too, is a need for challenging thermal conductivity measurements at micron and nanometer scales. In this thesis, we describe and demonstrate two techniques that combined are capable of measuring the key thermal transport properties in all of these regimes.We adapt the 3ω method—widely used for rigid, inorganic solids—as a reusable sensor to measure k of soft biological samples, two orders of magnitude thinner than conventional tissue characterization methods. Analytical and numerical studies quantify the error of the commonly used “boundary mismatch approximation” of the bi-directional 3ω geometry, confirm that the generalized slope method is exact in the low-frequency limit, and bound its error for finite frequencies. The bi-directional 3ω measurement device is validated using control experiments to within ± 2% (liquid water, std. dev.) and ± 5% (ice). Measurements of mouse liver cover a temperature range from -69 oC to + 33 oC. The liver results are independent of sample thicknesses from 3 mm down to 100 μm, and agree with available literature for non-mouse liver to within the measurement scatter.Next, we focus the laser spot 1/e^2 radius in TDTR measurements down to single micron length scales to measure quasi-ballistic thermal transport at length scales where Fourier’s law breaks down. We present an in-depth discussion of the instrumentation and provide comprehensive analyses of system sensitivities to all experimental parameters. The system is first validated on sapphire and single crystal silicon control samples. We then measure two nano-grained Si samples (550 nm and 76 nm average grain size) and two SiGe alloys (1% and 9.9% Ge concentration), representing two classes of silicon-based materials with qualitatively different phonon scattering physics. All samples are 5 mm x 5 mm x 0.5 mm or larger. Sub-diffusion measurements are performed on all samples using 1/e^2 laser spot radii down to 1.6 μm. Apparent thermal conductivity suppressions ranging from 18% to 76% are observed at room temperature, indicating that while most of the heat in sapphire, Si, and nano-grained Si is carried by phonons with mean free paths of a couple microns or less, much of the heat in SiGe alloys is still carried by phonons with mean free paths up to a few tens of microns at room temperature. We present a discussion of the microscale origins of this suppressed thermal conductivity and its physical interpretation, addressing some common misconceptions. Our results show that alloying and nanostructuring shift the spectral phonon mean free path distributions in opposite directions. Alloying skews the phonon distribution toward long mean free paths, increasing k suppression at small length scales, while nanostructuring skews the distribution toward short mean free paths, reducing k suppression." @default.
• W2945004535 created "2019-05-29" @default.
• W2945004535 creator A5044835767 @default.
• W2945004535 date "2016-01-01" @default.
• W2945004535 modified "2023-09-27" @default.
• W2945004535 title "Thermal Conductivity Measurements in Challenging Regimes" @default.
• W2945004535 hasPublicationYear "2016" @default.
• W2945004535 type Work @default.
• W2945004535 sameAs 2945004535 @default.
• W2945004535 citedByCount "0" @default.
• W2945004535 crossrefType "journal-article" @default.
• W2945004535 hasAuthorship W2945004535A5044835767 @default.
• W2945004535 hasConcept C121332964 @default.
• W2945004535 hasConcept C141400236 @default.
• W2945004535 hasConcept C171250308 @default.
• W2945004535 hasConcept C192562407 @default.
• W2945004535 hasConcept C202444582 @default.
• W2945004535 hasConcept C204530211 @default.
• W2945004535 hasConcept C207365445 @default.
• W2945004535 hasConcept C33923547 @default.
• W2945004535 hasConcept C50517652 @default.
• W2945004535 hasConcept C57879066 @default.
• W2945004535 hasConcept C9652623 @default.
• W2945004535 hasConcept C97346530 @default.
• W2945004535 hasConcept C97355855 @default.
• W2945004535 hasConceptScore W2945004535C121332964 @default.
• W2945004535 hasConceptScore W2945004535C141400236 @default.
• W2945004535 hasConceptScore W2945004535C171250308 @default.
• W2945004535 hasConceptScore W2945004535C192562407 @default.
• W2945004535 hasConceptScore W2945004535C202444582 @default.
• W2945004535 hasConceptScore W2945004535C204530211 @default.
• W2945004535 hasConceptScore W2945004535C207365445 @default.
• W2945004535 hasConceptScore W2945004535C33923547 @default.
• W2945004535 hasConceptScore W2945004535C50517652 @default.
• W2945004535 hasConceptScore W2945004535C57879066 @default.
• W2945004535 hasConceptScore W2945004535C9652623 @default.
• W2945004535 hasConceptScore W2945004535C97346530 @default.
• W2945004535 hasConceptScore W2945004535C97355855 @default.
• W2945004535 hasLocation W29450045351 @default.
• W2945004535 hasOpenAccess W2945004535 @default.
• W2945004535 hasPrimaryLocation W29450045351 @default.
• W2945004535 hasRelatedWork W1649863838 @default.
• W2945004535 hasRelatedWork W1966076571 @default.
• W2945004535 hasRelatedWork W1978652144 @default.
• W2945004535 hasRelatedWork W1985964803 @default.
• W2945004535 hasRelatedWork W1987250409 @default.
• W2945004535 hasRelatedWork W2021208262 @default.
• W2945004535 hasRelatedWork W2034004165 @default.
• W2945004535 hasRelatedWork W2057439512 @default.
• W2945004535 hasRelatedWork W2068930340 @default.
• W2945004535 hasRelatedWork W2079817863 @default.
• W2945004535 hasRelatedWork W2123605736 @default.
• W2945004535 hasRelatedWork W2277243037 @default.
• W2945004535 hasRelatedWork W2282754754 @default.
• W2945004535 hasRelatedWork W229260638 @default.
• W2945004535 hasRelatedWork W2472435346 @default.
• W2945004535 hasRelatedWork W258272547 @default.
• W2945004535 hasRelatedWork W2811188530 @default.
• W2945004535 hasRelatedWork W2885032126 @default.
• W2945004535 hasRelatedWork W47828399 @default.
• W2945004535 hasRelatedWork W2316620211 @default.
• W2945004535 isParatext "false" @default.
• W2945004535 isRetracted "false" @default.
• W2945004535 magId "2945004535" @default.
• W2945004535 workType "article" @default.