Rapid technological advancements drive miniaturization and high energy density in devices,thereby increasing nanoscale thermal management demands and urging development of higher spatial resolution technologies for th...Rapid technological advancements drive miniaturization and high energy density in devices,thereby increasing nanoscale thermal management demands and urging development of higher spatial resolution technologies for thermal imaging and transport research.Here,we introduce an approach to measure nanoscale thermal resistance using in situ inelastic scanning transmission electron microscopy.By constructing unidirectional heating flux with controlled temperature gradients and analyzing electron energy-loss/gain signals under optimized acquisition conditions,nanometer-resolution in mapping phonon apparent temperature is achieved.Thus,interfacial thermal resistance is determined by calculating the ratio of interfacial temperature difference to bulk temperature gradient.This methodology enables direct measurement of thermal transport properties for atomic-scale structural features(e.g.,defects and heterointerfaces),resolving critical structure-performance relationships,providing a useful tool for investigating thermal phenomena at the(sub-)nanoscale.展开更多
A mathematical model for insertion loss in a micro-perforated muffler with the effects of temperature gradient, gas flow speed and structure parameter is obtained by the mode matching technique. By dividing the microp...A mathematical model for insertion loss in a micro-perforated muffler with the effects of temperature gradient, gas flow speed and structure parameter is obtained by the mode matching technique. By dividing the microperforated tube into N segments, and assuming the flow speed and temperature are constant in each element, sound pressure and volume velocity of each segment can be readily acquired. The transmission matrix of microperforated muffler can be established based on the continuity condition of adjacent elements on the boundary. The numerical results of the present theory are calculated and the experiment is performed in Shanghai-495A engine. The experimental results of microperforated muffler show that they are in good agreement with the theoretical results.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52125307)the National Key R&D Program of China(Grant No.2021YFB3501500)the support from the New Cornerstone Science Foundation through the XPLORER PRIZE。
文摘Rapid technological advancements drive miniaturization and high energy density in devices,thereby increasing nanoscale thermal management demands and urging development of higher spatial resolution technologies for thermal imaging and transport research.Here,we introduce an approach to measure nanoscale thermal resistance using in situ inelastic scanning transmission electron microscopy.By constructing unidirectional heating flux with controlled temperature gradients and analyzing electron energy-loss/gain signals under optimized acquisition conditions,nanometer-resolution in mapping phonon apparent temperature is achieved.Thus,interfacial thermal resistance is determined by calculating the ratio of interfacial temperature difference to bulk temperature gradient.This methodology enables direct measurement of thermal transport properties for atomic-scale structural features(e.g.,defects and heterointerfaces),resolving critical structure-performance relationships,providing a useful tool for investigating thermal phenomena at the(sub-)nanoscale.
文摘A mathematical model for insertion loss in a micro-perforated muffler with the effects of temperature gradient, gas flow speed and structure parameter is obtained by the mode matching technique. By dividing the microperforated tube into N segments, and assuming the flow speed and temperature are constant in each element, sound pressure and volume velocity of each segment can be readily acquired. The transmission matrix of microperforated muffler can be established based on the continuity condition of adjacent elements on the boundary. The numerical results of the present theory are calculated and the experiment is performed in Shanghai-495A engine. The experimental results of microperforated muffler show that they are in good agreement with the theoretical results.
