Selectively Enhancing Solar Scattering for Direct Radiative Cooling through Control of Polymer Nanofiber Morphology

2020 ◽  
Vol 12 (39) ◽  
pp. 43553-43559
Author(s):  
Hannah Kim ◽  
Sean McSherry ◽  
Brendon Brown ◽  
Andrej Lenert
e-Polymers ◽  
2019 ◽  
Vol 19 (1) ◽  
pp. 190-202 ◽  
Author(s):  
Wenxing Zheng ◽  
Xinhou Wang

AbstractCylindrical-electrode-assisted solution blowing spinning (CSBS) is a novel method for preparing polymer nanofibers by using air-stretch and electrostatic simultaneously, which can fabricate thinner and more uniform nanofibers than the traditional solution blowing spinning (SBS). In this work, the effects of processing parameters including length of cylinder (LC), needle to cylinder distance (NCD) and left face of cylinder to collector distance (CCD) on the CSBS nanofiber diameter were investigated. The results are as follows: when the NCD decreased, the fiber diameter decreased; when the LC increased, the fiber diameter decreased; the CCD didn’t significantly affect the fiber diameter. Moreover, an orthogonal experimental design was utilized to investigate the effect of injection rate, air pressure, NCD, LC, diameter of cylinder (DC), voltage and CCD on the fiber diameter and porosity of various surface layers of nanofiber web (P1, P2, and P3). The results showed that the varied range of each properties (average diameter, standard deviation of the diameter, P1, P2, and P3) was 539.121-904.149 nm, 127.903-303.253, 71.464-85.1415%, 60.32725-75.46625%, 48.23925-70.08875%, respectively. We also found the order of the influence of the above-mentioned seven process parameters on each above properties of the nanofiber web, and the corresponding optimal spinning process parameters were listed. It is well known that the fiber diameter affects the mechanical properties of nanofibers, and porosity of nano-fiber webs is an important parameter in tissue engineering, bioengineering, and filtration. The effects of CSBS process parameters on nanofiber morphology and microstructure were investigated for the first time. The conclusion of the paper can help researchers to produce high quality CSBS nanofiber and promote the wider application of this novel technology.


2020 ◽  
Vol 640 ◽  
pp. A53
Author(s):  
L. Löhnert ◽  
S. Krätschmer ◽  
A. G. Peeters

Here, we address the turbulent dynamics of the gravitational instability in accretion disks, retaining both radiative cooling and irradiation. Due to radiative cooling, the disk is unstable for all values of the Toomre parameter, and an accurate estimate of the maximum growth rate is derived analytically. A detailed study of the turbulent spectra shows a rapid decay with an azimuthal wave number stronger than ky−3, whereas the spectrum is more broad in the radial direction and shows a scaling in the range kx−3 to kx−2. The radial component of the radial velocity profile consists of a superposition of shocks of different heights, and is similar to that found in Burgers’ turbulence. Assuming saturation occurs through nonlinear wave steepening leading to shock formation, we developed a mixing-length model in which the typical length scale is related to the average radial distance between shocks. Furthermore, since the numerical simulations show that linear drive is necessary in order to sustain turbulence, we used the growth rate of the most unstable mode to estimate the typical timescale. The mixing-length model that was obtained agrees well with numerical simulations. The model gives an analytic expression for the turbulent viscosity as a function of the Toomre parameter and cooling time. It predicts that relevant values of α = 10−3 can be obtained in disks that have a Toomre parameter as high as Q ≈ 10.


2020 ◽  
Vol 14 (1) ◽  
pp. 46-55 ◽  
Author(s):  
Zhi Liu ◽  
Lei Zhou ◽  
Fangtao Ruan ◽  
Anfang Wei ◽  
Jianghui Zhao ◽  
...  

Background: Nanofiber’s productivity plagues nanofibrous membranes’ applications in many areas. Herein, we present the needle-disk electrospinning to improve throughput. In this method, multiple high-curvature mentals are used as the spinning electrode. Methods: Three aspects were investigated: 1) mechanism elucidation of the needle-disk electrospinning; 2) parameter optimization of the needle-disk electrospinning; 3) productivity improvement of the needle-disk electrospinning. Results: Results show that high-curvature electrode evokes high electric field intensity, making lower voltage supply in spinning process. The needle number, needle length and needle curvature synergistically affect the spinning process and nanofiber morphology. Additionally, higher disk rotation velocity and higher voltage supply can also result in higher nanofiber’s productivity. Conclusion: Compared with previous patents related to this topic, the needle-disk electrospinning is featured with the merits of high throughput, low voltage supply, controllable spinning process and nanofiber morphology, benefiting the nanofiber practical industrial employment and further applications of nanofiber-based materials.


Nano Letters ◽  
2020 ◽  
Author(s):  
Yipeng Chen ◽  
Baokang Dang ◽  
Jinzhou Fu ◽  
Chao Wang ◽  
Caicai Li ◽  
...  

2021 ◽  
Vol 8 (10) ◽  
pp. 2170057
Author(s):  
Min Hyung Kang ◽  
Gil Ju Lee ◽  
Joong Hoon Lee ◽  
Min Seok Kim ◽  
Zheng Yan ◽  
...  
Keyword(s):  

2021 ◽  
Vol 230 ◽  
pp. 111275
Author(s):  
Roger Vilà ◽  
Ingrid Martorell ◽  
Marc Medrano ◽  
Albert Castell

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