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Age estimation from images can be used in many practical scenes. Most of the previous works targeted on the estimation from images in which only one face exists. Also, most of the open datasets for age estimation contain images like that. However, in some situations, age estimation in the wild and for multi-person is needed. Usually, such situations were solved by two separate models; one is a face detector model which crops facial regions and the other is an age estimation model which estimates from cropped images. In this work, we propose a method that can detect and estimate the age of multi-person with a single model which estimates age with focusing on faces and still seeing surroundings. Also, we propose a training method which enables the model to estimate multi-person well despite trained with images in which only one face is photographed. In the experiments, we evaluated our proposed method compared with the traditional approach using two separate models. As the result, the accuracy could be enhanced with our proposed method. We also adapted our proposed model to commonly used single person photographed age estimation datasets and it is proved that our method is also effective to those images and outperforms the state of the art accuracy., Comment: The precision and speed are improved from previous version with modified loss function and image size

Deformation of liquid droplets by impingement induces Worthington jet in certain range of the impact velocity. Although the growth of the jet as well as its tip velocity is predicted from similar cases to the droplet impact, the mechanism of the jet generation is yet to be understood. In this study, high-speed visualization of the droplet impact on a superhydrophobic surface was conducted to understand the initiation of the jet generated by a collapse of an air cavity. Water droplets whose diameter are 2.0 mm and 3.0 mm were generated and the Weber number of the droplet was varied in a range of 2 to 20. The jet velocity was measured from the captured images and it was found that it has a peak at the Weber number equals to approximately seven. The resulting jet velocity at the peak was approximately 15 folds higher than the impact velocity. Moreover, we observed that surface waves were generated by a collision of the droplet on the solid and the waves induced an oscillation of the droplet cap as they propagate from the solid-liquid contact line to the top portion of the droplet. Furthermore, we found the phase of the oscillation is related to the Weber number and it influences the jet velocity significantly, as it determines the initial condition of the jet generation., Comment: 8 pages, 4 figures

Because the superhydrophobic characteristic appears by forming a composite surface consisting of solid and air underneath the droplets, a large number of rough surfaces that can trap air have been fabricated. Recently, the air trapping on materials whose equilibrium contact angles are less than 90 degrees was achieved by fabricating proper structures that lead energetic stability at the condition. Whereas these methods were proposed under the assumption of the static and equilibrium conditions, we take a dynamic and non-equilibrium approach in this study through droplet deposition and droplet impact experiments. By employing test surfaces that consist of commercially available stainless steel razor blades, we show the pinning effect brings the apparent water contact angle of approximately 160 degrees on a "hydrophilic" substrate. We call this state the "non-equilibrium Cassie state" and give theoretical explanations. Furthermore, the dynamic characteristics of the droplet impact on these surfaces are discussed in a range of moderate Weber numbers., Comment: 17 pages, 10 figures