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Shaoqin Gong - One of the best experts on this subject based on the ideXlab platform.
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Flexible Infrared Responsive Multi-Walled Carbon Nanotube/Form-Stable Phase Change Material Nanocomposites
ACS Applied Materials & Interfaces, 2015Co-Authors: Yunming Wang, Hongyi Mi, Qifeng Zheng, Zhenqiang Ma, Shaoqin GongAbstract:Flexible infrared (IR)-responsive materials, such as polymer nanocomposites, that exhibit high levels of IR responses and short response times are highly desirable for various IR sensing applications. However, the IR-induced photoresponses of carbon nanotube (CNT)/polymer nanocomposites are typically limited to 25%. Herein, we report on a family of unique nanocomposite films consisting of multi-walled carbon nanotubes (MWCNTs) uniformly distributed in a form-Stable Phase change material (PCM) that exhibited rapid, dramatic, reversible, and cyclic IR-regulated responses in air. The 3 wt % MWCNT/PCM nanocomposite films demonstrated cyclic, IR-regulated on/off electrical conductivity ratios of 11.6 ± 0.6 and 570.0 ± 70.5 times at IR powers of 7.3 and 23.6 mW/mm2, respectively. The excellent performances exhibited by the MWCNT/PCM nanocomposite films were largely attributed to the IR-regulated cyclic and reversible form-Stable Phase transitions occurring in the PCM matrix due to MWCNT’s excellent photoabsorpt...
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flexible infrared responsive multi walled carbon nanotube form Stable Phase change material nanocomposites
ACS Applied Materials & Interfaces, 2015Co-Authors: Yunming Wang, Hongyi Mi, Qifeng Zheng, Shaoqin GongAbstract:Flexible infrared (IR)-responsive materials, such as polymer nanocomposites, that exhibit high levels of IR responses and short response times are highly desirable for various IR sensing applications. However, the IR-induced photoresponses of carbon nanotube (CNT)/polymer nanocomposites are typically limited to 25%. Herein, we report on a family of unique nanocomposite films consisting of multi-walled carbon nanotubes (MWCNTs) uniformly distributed in a form-Stable Phase change material (PCM) that exhibited rapid, dramatic, reversible, and cyclic IR-regulated responses in air. The 3 wt % MWCNT/PCM nanocomposite films demonstrated cyclic, IR-regulated on/off electrical conductivity ratios of 11.6 ± 0.6 and 570.0 ± 70.5 times at IR powers of 7.3 and 23.6 mW/mm2, respectively. The excellent performances exhibited by the MWCNT/PCM nanocomposite films were largely attributed to the IR-regulated cyclic and reversible form-Stable Phase transitions occurring in the PCM matrix due to MWCNT’s excellent photoabsorpt...
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graphene Phase change material nanocomposites light driven reversible electrical resistivity regulation via form Stable Phase transitions
ACS Applied Materials & Interfaces, 2015Co-Authors: Yunming Wang, Qifeng Zheng, Shaoqin GongAbstract:Innovative photoresponsive materials are needed to address the complexity of optical control systems. Here, we report a new type of photoresponsive nanomaterial composed of graphene and a form-Stable Phase change material (PCM) that exhibited a 3 orders of magnitude change in electrical resistivity upon light illumination while retaining its overall original solid form at the macroscopic level. This dramatic change in electrical resistivity also occurred reversibly through the on/off control of light illumination. This was attributed to the reversible Phase transition (i.e., melting/recrystallization) behavior of the microscopic crystalline domains present in the form-Stable PCM. The reversible Phase transition observed in the graphene/PCM nanocomposite was induced by a reversible temperature change through the on/off control of light illumination because graphene can effectively absorb light energy and convert it to thermal energy. In addition, this graphene/PCM nanocomposite also possessed excellent mec...
Yunming Wang - One of the best experts on this subject based on the ideXlab platform.
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Flexible Infrared Responsive Multi-Walled Carbon Nanotube/Form-Stable Phase Change Material Nanocomposites
ACS Applied Materials & Interfaces, 2015Co-Authors: Yunming Wang, Hongyi Mi, Qifeng Zheng, Zhenqiang Ma, Shaoqin GongAbstract:Flexible infrared (IR)-responsive materials, such as polymer nanocomposites, that exhibit high levels of IR responses and short response times are highly desirable for various IR sensing applications. However, the IR-induced photoresponses of carbon nanotube (CNT)/polymer nanocomposites are typically limited to 25%. Herein, we report on a family of unique nanocomposite films consisting of multi-walled carbon nanotubes (MWCNTs) uniformly distributed in a form-Stable Phase change material (PCM) that exhibited rapid, dramatic, reversible, and cyclic IR-regulated responses in air. The 3 wt % MWCNT/PCM nanocomposite films demonstrated cyclic, IR-regulated on/off electrical conductivity ratios of 11.6 ± 0.6 and 570.0 ± 70.5 times at IR powers of 7.3 and 23.6 mW/mm2, respectively. The excellent performances exhibited by the MWCNT/PCM nanocomposite films were largely attributed to the IR-regulated cyclic and reversible form-Stable Phase transitions occurring in the PCM matrix due to MWCNT’s excellent photoabsorpt...
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flexible infrared responsive multi walled carbon nanotube form Stable Phase change material nanocomposites
ACS Applied Materials & Interfaces, 2015Co-Authors: Yunming Wang, Hongyi Mi, Qifeng Zheng, Shaoqin GongAbstract:Flexible infrared (IR)-responsive materials, such as polymer nanocomposites, that exhibit high levels of IR responses and short response times are highly desirable for various IR sensing applications. However, the IR-induced photoresponses of carbon nanotube (CNT)/polymer nanocomposites are typically limited to 25%. Herein, we report on a family of unique nanocomposite films consisting of multi-walled carbon nanotubes (MWCNTs) uniformly distributed in a form-Stable Phase change material (PCM) that exhibited rapid, dramatic, reversible, and cyclic IR-regulated responses in air. The 3 wt % MWCNT/PCM nanocomposite films demonstrated cyclic, IR-regulated on/off electrical conductivity ratios of 11.6 ± 0.6 and 570.0 ± 70.5 times at IR powers of 7.3 and 23.6 mW/mm2, respectively. The excellent performances exhibited by the MWCNT/PCM nanocomposite films were largely attributed to the IR-regulated cyclic and reversible form-Stable Phase transitions occurring in the PCM matrix due to MWCNT’s excellent photoabsorpt...
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graphene Phase change material nanocomposites light driven reversible electrical resistivity regulation via form Stable Phase transitions
ACS Applied Materials & Interfaces, 2015Co-Authors: Yunming Wang, Qifeng Zheng, Shaoqin GongAbstract:Innovative photoresponsive materials are needed to address the complexity of optical control systems. Here, we report a new type of photoresponsive nanomaterial composed of graphene and a form-Stable Phase change material (PCM) that exhibited a 3 orders of magnitude change in electrical resistivity upon light illumination while retaining its overall original solid form at the macroscopic level. This dramatic change in electrical resistivity also occurred reversibly through the on/off control of light illumination. This was attributed to the reversible Phase transition (i.e., melting/recrystallization) behavior of the microscopic crystalline domains present in the form-Stable PCM. The reversible Phase transition observed in the graphene/PCM nanocomposite was induced by a reversible temperature change through the on/off control of light illumination because graphene can effectively absorb light energy and convert it to thermal energy. In addition, this graphene/PCM nanocomposite also possessed excellent mec...
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Visible light-driven organic form-Stable Phase change materials for solar energy storage
RSC Advances, 2012Co-Authors: Yunming Wang, Bingtao Tang, Shufen ZhangAbstract:A novel visible light-driven organic form-Stable Phase change material (VLDOPCM) exhibited excellent performances of light-harvesting, light-thermal conversion, thermal energy storage and form-Stable effect, which is promoted by the dye as an effective “photon capture and molecular heater” for direct and efficient use of solar radiation.
Qifeng Zheng - One of the best experts on this subject based on the ideXlab platform.
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Flexible Infrared Responsive Multi-Walled Carbon Nanotube/Form-Stable Phase Change Material Nanocomposites
ACS Applied Materials & Interfaces, 2015Co-Authors: Yunming Wang, Hongyi Mi, Qifeng Zheng, Zhenqiang Ma, Shaoqin GongAbstract:Flexible infrared (IR)-responsive materials, such as polymer nanocomposites, that exhibit high levels of IR responses and short response times are highly desirable for various IR sensing applications. However, the IR-induced photoresponses of carbon nanotube (CNT)/polymer nanocomposites are typically limited to 25%. Herein, we report on a family of unique nanocomposite films consisting of multi-walled carbon nanotubes (MWCNTs) uniformly distributed in a form-Stable Phase change material (PCM) that exhibited rapid, dramatic, reversible, and cyclic IR-regulated responses in air. The 3 wt % MWCNT/PCM nanocomposite films demonstrated cyclic, IR-regulated on/off electrical conductivity ratios of 11.6 ± 0.6 and 570.0 ± 70.5 times at IR powers of 7.3 and 23.6 mW/mm2, respectively. The excellent performances exhibited by the MWCNT/PCM nanocomposite films were largely attributed to the IR-regulated cyclic and reversible form-Stable Phase transitions occurring in the PCM matrix due to MWCNT’s excellent photoabsorpt...
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flexible infrared responsive multi walled carbon nanotube form Stable Phase change material nanocomposites
ACS Applied Materials & Interfaces, 2015Co-Authors: Yunming Wang, Hongyi Mi, Qifeng Zheng, Shaoqin GongAbstract:Flexible infrared (IR)-responsive materials, such as polymer nanocomposites, that exhibit high levels of IR responses and short response times are highly desirable for various IR sensing applications. However, the IR-induced photoresponses of carbon nanotube (CNT)/polymer nanocomposites are typically limited to 25%. Herein, we report on a family of unique nanocomposite films consisting of multi-walled carbon nanotubes (MWCNTs) uniformly distributed in a form-Stable Phase change material (PCM) that exhibited rapid, dramatic, reversible, and cyclic IR-regulated responses in air. The 3 wt % MWCNT/PCM nanocomposite films demonstrated cyclic, IR-regulated on/off electrical conductivity ratios of 11.6 ± 0.6 and 570.0 ± 70.5 times at IR powers of 7.3 and 23.6 mW/mm2, respectively. The excellent performances exhibited by the MWCNT/PCM nanocomposite films were largely attributed to the IR-regulated cyclic and reversible form-Stable Phase transitions occurring in the PCM matrix due to MWCNT’s excellent photoabsorpt...
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graphene Phase change material nanocomposites light driven reversible electrical resistivity regulation via form Stable Phase transitions
ACS Applied Materials & Interfaces, 2015Co-Authors: Yunming Wang, Qifeng Zheng, Shaoqin GongAbstract:Innovative photoresponsive materials are needed to address the complexity of optical control systems. Here, we report a new type of photoresponsive nanomaterial composed of graphene and a form-Stable Phase change material (PCM) that exhibited a 3 orders of magnitude change in electrical resistivity upon light illumination while retaining its overall original solid form at the macroscopic level. This dramatic change in electrical resistivity also occurred reversibly through the on/off control of light illumination. This was attributed to the reversible Phase transition (i.e., melting/recrystallization) behavior of the microscopic crystalline domains present in the form-Stable PCM. The reversible Phase transition observed in the graphene/PCM nanocomposite was induced by a reversible temperature change through the on/off control of light illumination because graphene can effectively absorb light energy and convert it to thermal energy. In addition, this graphene/PCM nanocomposite also possessed excellent mec...
Guiyin Fang - One of the best experts on this subject based on the ideXlab platform.
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Palmitic acid/polyvinyl butyral/expanded graphite composites as form-Stable Phase change materials for solar thermal energy storage
Applied Energy, 2018Co-Authors: Yaxue Lin, Chuqiao Zhu, Guruprasad Alva, Guiyin FangAbstract:Abstract In order to improve the performances of Phase change material (PCM) in applications, a novel form-Stable Phase change materials were fabricated via solution blending method in this work. Palmitic acid (PA) was used as Phase change material to release and absorb large amounts of latent heat at operating temperature. Polyvinyl butyral (PVB) is the polymer that was used as supporting matrix to prevent the leakage of palmitic acid in melting state. Expanded graphite (EG) was used not only to enhance thermal conductivity of form-Stable Phase change materials, but also to help reduce leakage. A series of form-Stable Phase change materials were prepared, containing pure palmitic acid/polyvinyl butyral composites, and palmitic acid/polyvinyl butyral composites doped with expanded graphite of 3 wt%, 5 wt% and 7 wt%. Fourier transformation infrared spectroscope (FT-IR), X-ray diffractometer (XRD), scanning electronic microscope (SEM) and thermal gravimetric analyzer (TGA) were used to analyze the chemical structures, crystal structures, microstructure and thermal stability of the form-Stable Phase change materials. Thermal storage properties were determined by differential scanning calorimeter (DSC), the latent heat value of form-Stable Phase change material with the highest palmitic acid content (70 wt%) was 128.08 J/g, corresponding to melting point of 59.5 °C. The thermal conductivity of form-Stable Phase change materials which was measured by thermal conductivity meter (TCM) was greatly enhanced by expanded graphite, and the thermal conductivity of form-Stable Phase change materials can be increased 4.2 times by 7 wt% expanded graphite. Therefore, the novel form-Stable Phase change materials are promising in thermal energy storage systems, especially in low-temperature solar energy systems.
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palmitic acid polyvinyl butyral expanded graphite composites as form Stable Phase change materials for solar thermal energy storage
Applied Energy, 2018Co-Authors: Yaxue Lin, Chuqiao Zhu, Guruprasad Alva, Guiyin FangAbstract:Abstract In order to improve the performances of Phase change material (PCM) in applications, a novel form-Stable Phase change materials were fabricated via solution blending method in this work. Palmitic acid (PA) was used as Phase change material to release and absorb large amounts of latent heat at operating temperature. Polyvinyl butyral (PVB) is the polymer that was used as supporting matrix to prevent the leakage of palmitic acid in melting state. Expanded graphite (EG) was used not only to enhance thermal conductivity of form-Stable Phase change materials, but also to help reduce leakage. A series of form-Stable Phase change materials were prepared, containing pure palmitic acid/polyvinyl butyral composites, and palmitic acid/polyvinyl butyral composites doped with expanded graphite of 3 wt%, 5 wt% and 7 wt%. Fourier transformation infrared spectroscope (FT-IR), X-ray diffractometer (XRD), scanning electronic microscope (SEM) and thermal gravimetric analyzer (TGA) were used to analyze the chemical structures, crystal structures, microstructure and thermal stability of the form-Stable Phase change materials. Thermal storage properties were determined by differential scanning calorimeter (DSC), the latent heat value of form-Stable Phase change material with the highest palmitic acid content (70 wt%) was 128.08 J/g, corresponding to melting point of 59.5 °C. The thermal conductivity of form-Stable Phase change materials which was measured by thermal conductivity meter (TCM) was greatly enhanced by expanded graphite, and the thermal conductivity of form-Stable Phase change materials can be increased 4.2 times by 7 wt% expanded graphite. Therefore, the novel form-Stable Phase change materials are promising in thermal energy storage systems, especially in low-temperature solar energy systems.
Rujie Yin - One of the best experts on this subject based on the ideXlab platform.
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Stable Phase retrieval in infinite dimensions
Foundations of Computational Mathematics, 2019Co-Authors: Rima Alaifari, Philipp Grohs, Ingrid Daubechies, Rujie YinAbstract:The problem of Phase retrieval is to determine a signal \(f\in \mathcal {H}\), with \( \mathcal {H}\) a Hilbert space, from intensity measurements \(|F(\omega )|\), where \(F(\omega ):=\langle f, \varphi _\omega \rangle \) are measurements of f with respect to a measurement system \((\varphi _\omega )_{\omega \in \Omega }\subset \mathcal {H}\). Although Phase retrieval is always Stable in the finite-dimensional setting whenever it is possible (i.e. injectivity implies stability for the inverse problem), the situation is drastically different if \(\mathcal {H}\) is infinite-dimensional: in that case Phase retrieval is never uniformly Stable (Alaifari and Grohs in SIAM J Math Anal 49(3):1895–1911, 2017; Cahill et al. in Trans Am Math Soc Ser B 3(3):63–76, 2016); moreover, the stability deteriorates severely in the dimension of the problem (Cahill et al. 2016). On the other hand, all empirically observed instabilities are of a certain type: they occur whenever the function |F| of intensity measurements is concentrated on disjoint sets \(D_j\subset \Omega \), i.e. when \(F= \sum _{j=1}^k F_j\) where each \(F_j\) is concentrated on \(D_j\) (and \(k \ge 2\)). Motivated by these considerations, we propose a new paradigm for Stable Phase retrieval by considering the problem of reconstructing F up to a Phase factor that is not global, but that can be different for each of the subsets \(D_j\), i.e. recovering F up to the equivalence $$\begin{aligned} F \sim \sum _{j=1}^k e^{\mathrm {i}\alpha _j} F_j. \end{aligned}$$ We present concrete applications (for example in audio processing) where this new notion of stability is natural and meaningful and show that in this setting Stable Phase retrieval can actually be achieved, for instance, if the measurement system is a Gabor frame or a frame of Cauchy wavelets.
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Stable Phase Retrieval in Infinite Dimensions
arXiv: Functional Analysis, 2016Co-Authors: Rima Alaifari, Philipp Grohs, Ingrid Daubechies, Rujie YinAbstract:The problem of Phase retrieval is to determine a signal $f\in \mathcal{H}$, with $\mathcal{H}$ a Hilbert space, from intensity measurements $|F(\omega)|$, where $F(\omega):=\langle f , \varphi_\omega\rangle$ are measurements of $f$ with respect to a measurement system $(\varphi_\omega)_{\omega\in \Omega}\subset \mathcal{H}$. Although Phase retrieval is always Stable in the finite dimensional setting whenever it is possible (i.e. injectivity implies stability for the inverse problem), the situation is drastically different if $\mathcal{H}$ is infinite-dimensional: in that case Phase retrieval is never uniformly Stable [8, 4]; moreover the stability deteriorates severely in the dimension of the problem [8]. On the other hand, all empirically observed instabilities are of a certain type: they occur whenever the function $|F|$ of intensity measurements is concentrated on disjoint sets $D_j\subset \Omega$, i.e., when $F= \sum_{j=1}^k F_j$ where each $F_j$ is concentrated on $D_j$ (and $k \geq 2$). Motivated by these considerations we propose a new paradigm for Stable Phase retrieval by considering the problem of reconstructing $F$ up to a Phase factor that is not global, but that can be different for each of the subsets $D_j$, i.e., recovering $F$ up to the equivalence $$ F \sim \sum_{j=1}^k e^{i \alpha_j} F_j.$$ We present concrete applications (for example in audio processing) where this new notion of stability is natural and meaningful and show that in this setting Stable Phase retrieval can actually be achieved, for instance if the measurement system is a Gabor frame or a frame of Cauchy wavelets.
