||Haidong Wang, Xing Zhang, Hiroshi Takamatsu and Koji Takahashi, Effective thermal rectification in suspended monolayer graphene, 16th International Heat Transfer Conference, 2018.08.
||Haidong WANG, Takanobu FUKUNAGA, Kosaku KURATA, Hiroshi TAKAMATSU, 架橋単層カーボンナノチュブの熱伝導解析, 第55回 日本伝熱シンポジウム, 2018.05.
||Haidong Wang, Xing Zhang, Hiroshi Takamatsu and Koji Takahashi, Thermal rectification in suspended monolayer graphene, 9th US-Japan Joint Seminar on Nanoscale Transport Phenomena, 2017.07.
||Haidong Wang, Hiroshi Takamatsu, Koji Takahashi and Xing Zhang, 単層グラフェンの熱流束制御技術に関する研究, 第65回応用物理学会春季学術講演会, 2018.03.
||DONG HAI WANG, Hiroshi Takamatsu, Xing Zhang, Width-dependent thermal conductivity of suspended single- layer graphene, 1st Asian Conference on Thermal Science , 2017.03.
||DONG HAI WANG, Koji Takahashi, Hiroshi Takamatsu, Xing Zhang, Highly sensitive charge mobility of suspended monolayer graphene, 6 th International Symposium on Micro and Nano Technology, 2017.03.
||DONG HAI WANG, Hisada Kosuke, Kosaku Kurata, Fukunaga Takanobu, Hiroshi Takamatsu, Feasibility of using micro-beam sensor for gas detection, size effect on heat conduction to gases, 1st Pacific Rim Thermal Engineering Conference , 2016.03.
||DONG HAI WANG, Hiroshi Takamatsu, Koji Takahashi, Xing Zhang, Effect of nanohole defect on the thermal conductivity of free-standing single-layer graphene
, 11th Asian Thermophysical Properties Conference, ATPC2016, 2016.10, In this paper, we report thermal conductivity of free-standing single-layer graphene measured using a T-type sensor method. After measuring a defect-free graphene, we examined the effect of nanoholes created in situ using a focused ion beam. The thermal conductivity was ~2300 Wm-1K-1 at room temperature and decreased as temperature increased. It decreased by about 42% after creating the nanoholes. The lattice dynamics theory indicated that the decrease was a result of the increase of edge roughness and stronger scattering on long-wavelength acoustic phonons..
||DONG HAI WANG, Hiroshi Takamatsu, Width dependent thermal conductivity of suspended monolayer graphene, The Eighth KAIST-Kyushu University Joint Workshop 2016, 2016.09, As the thinnest membrane, graphene has an ultra-high thermal conductivity over 3000 W/mK. Phonons are the main heat carriers in graphene. Different from the bulk-size material, a significant size effect exists in graphene, reflecting the unique phonon transport in two-dimensional materials. Here, we fabricated four suspended graphene samples bridged between a thin film sensor and heat sink. The sensor was used as a DC current heater and precise thermometer at the same time. The average temperature difference of sensor with and without graphene was proportional to the thermal conductivity of sample. Comparing the measured temperature difference with the thermal analysis result, the thermal conductivity of graphene could be calculated. The result demonstrated that the wide graphene had larger thermal conductivity than the narrow sample. The phonon confinement at the lateral boundaries was the underlying mechanism for the width dependence. Narrow graphene imposed more limitation on the phonon transport and reduced the thermal conductivity accordingly..
||DONG HAI WANG, Kosaku Kurata, Hiroshi Takamatsu, Takanobu Fukunaga, Thermal conductivity of suspended monolayer graphene measured by a T-type sensor, 第53回日本伝熱シンポジウム, 2016.05, The thermal conductivity of a free-standing monolayer graphene ribon was measured by a T-type sensor method. A 10μm long gold nanofilm was suspended and used as a precise thermometer. A 2μm wide monolayer graphene ribbon was clamped to the sensor in the middle. By comparing the average temperature of sensor with and without graphene, its thermal conductivity could be calculated. The result indicates a value of 2300 W/mK at room temperature, decreasing as the temperature increases..
||DONG HAI WANG, Kento Inui, Takanobu Fukunaga, Kosaku Kurata, Hiroshi Takamatsu, Measuring thermal conductivity of gases and liquids ranged from 0.03 to 0.6 w/(m k) using a single micro-beam sensor, 日本熱物性学会, 2015.10, The present work demonstrated the measurement of air and six kinds of liquids including water using a single sensor. The measured thermal conductivity ranged from 0.03 to 0.6 W/(mK) agreed well with literature values within 5 % error..
||DONG HAI WANG, Kento Inui, Takanobu Fukunaga, Kosaku Kurata, Hiroshi Takamatsu, Measurement of liquid thermal conductivity using a micro-beam MEMS sensor, 日本伝熱学会, 2015.06, A micro-beam MEMS sensor was designed for measuring the thermal conductivity of a microliter liquid sample. The MEMS sensor serves as a precise Joule heater and a thermometer at the same time..
||田中柊郎, 西村和洋, WANG HAIDONG, 福永鷹信, 藏田 耕作, 高松 洋, 白金マイクロビームセンサによる熱伝導率測定に水素が与える影響, 日本機械学会九州学生会第46回卒業研究発表講演会, 2015.03.
||西村和洋, WANG HAIDONG, 福永鷹信, 藏田 耕作, 高松 洋, マイクロビームMEMSセンサを用いた金薄膜の面方向熱伝導率・電気伝導率測定, 第35回日本熱物性シンポジウム, 2014.11.
||DONG HAI WANG, Raman measurement of heat transfer in suspended individual carbon nanotube
, 7th Kyushu University-KAIST Joint Workshop on Frontiers in Mechanical Engineering, 2014.09, Carbon nanotube (CNT) has super-high thermal conductivity. However, due to the difficulty of thermal measurement of an individual CNT, the available experimental data are still very few. In this paper, we used a micro-Raman spectroscopy technique to measure the thermal conductivity of an individual CNT. The thermal conductivity was obtained by measuring the temperature rise caused by a direct current heating, where the laser heating effect could be eliminated. Then the optical absorption was obtained by solving the heat transfer equation considering the thermal conductivity as a known parameter. The measured CNT sample was 24.8 μm in length and 3 nm in diameter. The measured thermal conductivity was 2630 W/mK and the optical absorption was 0.194%. The heat transfer coefficient of CNT was evaluated using a kinetic two-layer model, which had been proven by the previous experiments. Because the length of CNT was much larger than the size of the focused laser spot, the experimental result was insensitive to the contact resistances at the ends of CNT..
||DONG HAI WANG, Experimental and theoretical study of steady non-fourier heat conduction in free-standing gold nanofilm, 15th International Heat Transfer Conference, 2014.08, Fourier’s law has been found to be violated for heat conduction in low-dimensional materials, but no fully developed theoretical models have been proposed so far. Recently, a thermomass theory has been developed by Guo based on Einstein’s mass-energy relation. The momentum conservation equation of thermomass is referred to as the general heat conduction law, which is capable of predicting the non-Fourier phenomena under the extreme heat conduction conditions quantitatively and reduces to Fourier’s law under the normal heat conduction conditions. The violation of Fourier’s law is revealed to be the consequence of non-negligible inertia term in the momentum conservation equation of thermomass. In the experiment, a free-standing gold nanofilm is heated by a large current in the temperature range from 3 K to 60 K, while the maximum heat flux exceeds 2×1010 W/m2. The measured average temperature of the gold film is remarkably higher than the prediction of Fourier’s law, but agrees well with the prediction of the general heat conduction law without any adjustable parameters. Hence, the validity of the general heat conduction law has been proved experimentally. Our results provide strong evidence for the existence of non-Fourier heat conduction in steady states, and the general heat conduction law shows a great potential in accurate thermal design of nanoelectric devises with ultra-high heat flux generation..