Sessile droplet evaporation on superheated superhydrophobic surfaces

This fluid dynamics video depicts the evaporation of sessile water droplets placed on heated superhydrophobic (SH) surfaces of varying cavity fraction, F_c, and surface temperature, T_s, above the saturation temperature, T_sat. Images were captured at 10,000 FPS and are played back at 30 FPS in this video. Teflon-coated silicon surfaces of F_c = 0, 0.5, 0.8, and 0.95 were used for these experiments. T_s ranging from 110{\deg}C to 210{\deg}C were studied. The video clips show how the boiling behavior of sessile droplets is altered with changes in surface microstructure. Quantitative results from heat transfer rate experiments conducted by the authors are briefly discussed near the end of the video.Comment: videos include

Liquid Droplet Impact Dynamics on Micro-Patterned Superhydrophobic Surfaces

The video exhibits experimental qualitative and quantitative results of water/glycerol (50%/50% by mass) droplet impact on two types of micro-patterned superhydrophobic surfaces. The two types of surfaces used were 80% cavity fraction ribs and posts with a periodic spacing of 40 {\mu}m and 32 {\mu}m, respectively. All surfaces were manufactured through photolithography. The impact Weber number is used as the dynamic parameter to compare splash and rebound behaviors between the two types of surfaces. While droplets exhibit similar dynamics at low Weber numbers, rebound jet speed (normalized by droplet impact speed) is notably higher on posts than ribs for all Weber numbers tested here (5<We<900). At elevated Weber numbers, droplets splash peripherally. These side droplets created at splash are referred to as satellite droplets. Top view videos show the significant difference in splashing behavior for the two surface types. On ribs, satellite droplet formation consistently prefers a path 60{\deg} from the ribs longitudinal direction. This behavior prevails for Weber numbers greater than 150, however, distinguished splashing does not occur for We > 265. On posts, satellite droplets also follow a specific path but in a different orientation. Satellite droplets form in locations aligned with the post lattice structure. This behavior is observed for 600 < We < 750. Jet rebound exhibits an interesting phenomenon on ribs under certain conditions. Due to the uneven shear distribution on the retracting droplet due to the surface anisotropy, two jets form at rebound and are referred to as two-pronged jets. This behavior occurs for 115 < We < 265 on ribs. Two-pronged jets are also observed on posts but are less coherent and less repetitive. This behavior was observed at around 500 < We < 600.Comment: videos are include

Measuring Condensation Heat Transfer on Superhydrophobic Surfaces

Condensation heat transfer is significant in many applications such as desalination, energy conversion, atmospheric water harvesting, electronics cooling, and other high heat flux applications. However, condensate on the surface adds a thermal resistance that limits condensation rates. The rate of condensation heat transfer is inversely proportional to the diameter of the condensate drops. In industrial condensing systems, the resistance is minimized by removing the condensate via gravity or a vapor shear, but the minimum size of droplet removal is typically on the order of the capillary length of the condensate, about 2.7 mm for water

An Optical-based Aggregate Approach to Measuring Condensation Heat Transfer

Condensation heat transfer is significant in many applications such as such as desalination, energy conversion [1], atmospheric water harvesting [2, 3], electronics cooling, and other high heat flux applications [4]. However, condensate on the surface adds a thermal resistance that limits condensation rates. The rate of condensation heat transfer is inversely proportional to the diameter of the condensate drops [5]. In industrial condensing systems, the resistance is minimized by removing the condensate via gravity or a vapor shear, but the minimum size of droplet removal is typically on the order of the capillary length of the condensate, about 2.7 mm for water

Garotas de loja, história social e teoria social [Shop Girls, Social History and Social Theory]

Shop workers, most of them women, have made up a significant proportion of Britain’s labour force since the 1850s but we still know relatively little about their history. This article argues that there has been a systematic neglect of one of the largest sectors of female employment by historians and investigates why this might be. It suggests that this neglect is connected to framings of work that have overlooked the service sector as a whole as well as to a continuing unease with the consumer society’s transformation of social life. One element of that transformation was the rise of new forms of aesthetic, emotional and sexualised labour. Certain kinds of ‘shop girls’ embodied these in spectacular fashion. As a result, they became enduring icons of mass consumption, simultaneously dismissed as passive cultural dupes or punished as powerful agents of cultural destruction. This article interweaves the social history of everyday shop workers with shifting representations of the ‘shop girl’, from Victorian music hall parodies, through modernist social theory, to the bizarre bombing of the Biba boutique in London by the Angry Brigade on May Day 1971. It concludes that progressive historians have much to gain by reclaiming these workers and the service economy that they helped create

AI is a viable alternative to high throughput screening: a 318-target study

: High throughput screening (HTS) is routinely used to identify bioactive small molecules. This requires physical compounds, which limits coverage of accessible chemical space. Computational approaches combined with vast on-demand chemical libraries can access far greater chemical space, provided that the predictive accuracy is sufficient to identify useful molecules. Through the largest and most diverse virtual HTS campaign reported to date, comprising 318 individual projects, we demonstrate that our AtomNet® convolutional neural network successfully finds novel hits across every major therapeutic area and protein class. We address historical limitations of computational screening by demonstrating success for target proteins without known binders, high-quality X-ray crystal structures, or manual cherry-picking of compounds. We show that the molecules selected by the AtomNet® model are novel drug-like scaffolds rather than minor modifications to known bioactive compounds. Our empirical results suggest that computational methods can substantially replace HTS as the first step of small-molecule drug discovery

Interactive visual prototyping of computer vision applications

Cameras are a useful source of input for many interactive applications, but computer vision programming is difficult and requires specialized knowledge that is out of reach for many application developers. This dissertation contributes a novel architectural framework for developing computer vision applications, in which developers use visual examples to train and tune computer vision recognizers. We claim that this framework allows people with minimal programming experience, and no specialized knowledge of computer vision, to use camera data in a wide variety of compelling camera-based applications: home monitoring and surveillance, automated reminder systems, robotic navigation, interactive art, gesture-controlled appliances, video games, and many others. We demonstrate our claim through the design and evaluation of a prototyping tool for camera-based interaction, which we built, distributed, and incrementally refined over the course of several years. In addition to presenting a new software framework for building computer vision applications, and an associated set of interaction techniques, this thesis describes the lessons we learned in the process of evaluating and improving our approach. We discuss how to package complex algorithms in a way that makes them accessible and practical; how to strike a balance between power and flexibility on the one hand, and simplicity and ease of use on the other; and how to address the unique set of challenges and opportunities presented when using computer vision in real-world applications

Applications of computer-controlled actuation in workbench tangible user interfaces

Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2003.Includes bibliographical references (p. 60-62).Tangible user interfaces give physical form to digital information, bridging the gap between the digital world of bits and the physical world of atoms. They offer many advantages over traditional graphical user interfaces, including two-handed manipulation, simplified multi-user collaboration, and the use of natural human spatial and tactile abilities. In the majority of existing tangible interfaces, different modalities are used for input and output; while the user provides input through the manipulation of physical objects, the computer produces only graphical output. This can lead to inconsistencies between the digital and physical representations of the same object. The goal of this thesis is to address this limitation by adding computer-controlled actuation to tangible interfaces. Actuation allows the computer to manipulate graspable objects the same way that a human user can. By developing and evaluating a variety of applications that use actuation, we demonstrate how it can best be employed in tangible interfaces.by Daniel Maynes-Aminzade.S.M