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Dew collection, and devices for such, may play an important role in regions of our planet that are arid and lack clean water. Usually, dew collection devices are represented as an inclined plane, which is a trivial topology. In this work, we first propose the concept a dew collection device with a helicoidal structure in order to increase its surfa...

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... (a) (b) Figure 1. Applications of ruled surfaces: (a) AI-enhanced image of a dew collector based on a ruled surface (helicoid) [13]. (b) The grid shell of the Shukhov Tower in Moscow, whose sections are doubly ruled. ...

... Helicoid, which has many applications in engineering [13], is a very good example of this type of developable surface. It is also known as the tangent-developable surface of a circular helix curve. ...

... α i (s) = sin(κs)C i1 + cos(κs)C i2 + κ sin(κs) cos(κs)x i (s)ds − cos(κs) sin(κs)x i (s)ds (13) where C i1 , C i2 are constants. ...

Ruled surfaces play an important role in various types of design, architecture, manufacturing, art, and sculpture. They can be created in a variety of ways, which is a topic that has been the subject of a lot of discussion in mathematics and engineering journals. In geometric modelling, ideas are successful if they are not too complex for engineers and practitioners to understand and not too difficult to implement, because these specialists put mathematical theories into practice by implementing them in CAD/CAM systems. Some of these popular systems such as AutoCAD, Solidworks, CATIA, Rhinoceros 3D, and others are based on simple polynomial or rational splines and many other beautiful mathematical theories that have not yet been implemented due to their complexity. Based on this philosophy, in the present work, we investigate a simple method of generating ruled surfaces whose generators are the curvature axes of curves. We show that this type of ruled surface is a developable surface and that there is at least one curve whose curvature axis is a line on the given developable surface. In addition, we discuss the classifications of developable surfaces corresponding to space curves with singularities, as these curves and surfaces are most often avoided in practical design. Our research also contributes to the understanding of the singularities of developable surfaces and, in their visualisation, proposes the use of environmental maps with a circular pattern that creates flower-like structures around the singularities.

... However, there has been recent renewed interest in dew as a supplemental water source (Muselli et al., 2002;Beysens et al., 2007;Sharan et al., 2011;Sharan, 2011;Tomaszkiewicz et al., 2015;Khalil et al., 2016) as our understanding of condenser physics (Nikolayev et al., 1996), radiative cooling (Head, 1959;Bliss, 1961;Nilsson et al., 1992;Hossain and Gu, 2016;Zeyghami et al., 2018;Zhou et al., 2018;Dong et al., 1961;Zhao et al., 2019), and dew formation (Beysens, 1995;Agam and Berliner, 2006) have improved, and high-yield materials have come to bear (Beysens et al., 2003;Maestre-Valero et al., 2011;Maestre-Valero et al., 2012;Chen et al., 2016;Zhai et al., 2017;Bintein et al., 2019;Bao et al., 2017;Guan et al., 2013;Al-Khayat et al., 2017). In an effort to optimize dew yields, many parameters have been studied including: wind speed (Clus et al., 2008;Muselli et al., 2009), angle of the collector (Kidron, 2005;Beysens et al., 2003), shape of the apparatus (Jacobs et al., 2008;Ziatdinov et al., 2019;Beysens et al., 2013;Kotzen, 2015;Beysens et al., 2021) and scaling of dew collectors (Carvajal et al., 2018;Sharan et al., 2017) to name a few. ...

We derive a general, tilt-dependent, nighttime, radiative deficit model with an eye towards improved dew collection. The model incorporates atmospheric/environmental incoming radiation, a linear precipitable water vapor transmittance function dependent on local meteo data and the influence of near-horizon obstacles. A brief discussion of cloud cover is given. The model is then used more specifically to predict radiative deficits for an ideal blackbody emitter in an environment with an isotropic temperature. Knowing the tilt angle, near-horizon obstacles and local meteo-data, it is then possible to estimate the radiative deficit of a given emitter. We consider errors resulting from the assumption that the ground and obstacles are at the same temperature as the air. We also analyze the errors arising from the linear precipitable water vapor transmittance function by comparing the results against high-resolution, full-spectrum Modtran® data Modtran, YYYY. We show that for typical tilt angles, the isotropic temperature model is a reasonable approximation as long as the above-horizon environmental heating is small. We believe these results will be broadly valuable for the field of radiative cooling where a general radiative treatment has yet to be made and in particular the field of dew water harvesting.

The fog harvesting rate of vertical filament mesh depends on improving the synergistic effects of fog capture, droplet growth, and shedding. In the study, we investigated the droplet behavior of several textile fibers. In which, a core-shell vertical filament structure (PET/PMMA) was developed by Electrospinning technology. The result was that droplet shedding of the PET/PMMA core-shell vertical filament was earlier than that of the original PET filament approximately 10 times. Besides, the novel result of a twisted structure of thread affecting the droplet condensation was reported. We hope that this new study will further contribute to the development of water harvesting by using vertical mesh fog based on taking advantage of the superior properties of different textile fibers.KeywordsDroplet condensationDroplet growingDroplet sheddingFilamentFog harvestingYarnThreadVertical filament mesh