This paper describes the instrumentation for broadband frequency domain thermoreflectance (BB-FDTR), a novel, continuous wave laser technique for measuring the thermal conductivity accumulation function. The thermal conductivity accumulation function describes cumulative contributions to the bulk thermal conductivity of a material from energy carriers with different mean free paths. It can be u...

As a hot research topic nanofluids have attracted great interest from researchers worldwide. Although nanofluids are found to exhibit higher thermal conductivity compared to their base fluids, the underlying mechanisms for the enhancement are still debated and not fully understood. In addition, there has been little agreement among different studies and no widely accepted model is also availabl...

Size effects in heat conduction, which occur when phonon mean free paths (MFPs) are comparable to characteristic lengths, are being extensively explored in many nanoscale systems for energy applications. Knowledge of MFPs is essential to understanding size effects, yet MFPs are largely unknown for most materials. Here, we introduce the first experimental technique which can measure MFP distribu...

Thermomechanical analysis (TMA) measures the mechanical response of a material as it is programmed linearly through a selected temperature range.' The techniques used in TMA include linear expansion, volumetric expansion, tensile elongation, torsional modulus, and penetration. Comparison of TMA penetration curves with curves of transition temperatures obtained from differential thermal analysis...

BACKGROUND Aimed to develop a unitary scoring system for the 'Health Behaviour in school-aged Children' (HBSC) symptom checklist that would facilitate cross-national comparisons and interpretation. Rasch measurement analysis and investigation of differential item functioning (DIF) were conducted. METHODS Data were obtained from the 'WHO collaborative study HBSC 2001/2002'. A total of 162,305 ...

One of the most important physical factors related to the thermal conductivity of composites filled with graphene nanoplatelets (GNPs) is the dimensions of the GNPs, that is, their lateral size and thickness. In this study, we reveal the relationship between the thermal conductivity of polymer composites and the realistic size of GNP fillers within the polymer composites (measured using three-d...

The effect of nanoparticle size (4~44 nm) on the thermal conductivities of heat transfer oils has been systematically examined using iron oxide nanoparticles. Such Fe(3)O(4) nanoparticles were synthesized by a simple one-pot pyrolysis method. The size (16~44 nm), shape and assembly patterns of monodisperse Fe(3)O(4) nanoparticles were modulated by only controlling the amount of Fe(acac)(3). Aft...

This paper reports on the dissipation of heat generated by a high power LED array using piezoelectric fans. Both numerical and experimental studies were carried out to evaluate the heat dissipation efficiency of high power LED package operating under multiple vibrating fans. Two vibrating fans were vertically oriented to the LED package and arranged according to configuration A (for edge to edg...

Yb2O3 is an efficient sintering additive for enhancing not only thermal conductivity but also the high-temperature mechanical properties of Si3N4 ceramics. Here we report the fabrication of dense Si3N4 ceramics with high thermal conductivity by the gas pressure sintering of α-Si3N4 powder compacts, using only Yb2O3 as an additive, at 1900 °C under a nitrogen pressure of 1 MPa. The effects of Yb...