Quantum vacuum photon-modes and superhydrophobicity

Nanostructures are commonly used for developing superhydrophobic surfaces. However, available wetting theoretical models ignore the effect of vacuum photon-modes alteration on van der Waals forces and thus on hydrophobicity. Using first-principle calculations, we show that superhydrophibicity of nanostructured surfaces is dramatically enhanced by vacuum photon-modes tuning. As a case study, wetting contact angles of a water droplet above a polyethylene nanostructured surface are obtained from the interaction potential energy calculated as function of the droplet-surface separation distance. This new approach could pave the way for the design of novel superhydrophobic coatings.Comment: 5 pages, 4 figures, final version published in Physical Review Letter

Sweet Kentucky Lady : Dry Your Eyes

https://digitalcommons.library.umaine.edu/mmb-vp/3383/thumbnail.jp

Use of resonance Raman spectroscopy to study the phase diagram of PbZr0.52Ti0.48O3

Evidence is presented for the first time that the sharp and continuous spectral changes observed in PbZr0.52Ti0.48O3 (PZT) between 350 and 10 K with the 647.1 nm wavelength are due to a resonance Raman effect. Such a phenomenon can be explained by means of a self-trapped exciton emission oxygen deficient complex (TiTi' - VO-) of PZT powder whose energy is close to the radiation line of the laser. This kind of approach should also be very useful to distinguish the phase transition sequence for other related ferro/ piezoelectric systems

Coastal Marine Debris Mapping Using Multi-Modal Feature Extraction Pipeline

Marine debris in the ocean is becoming an increasing problem for the management of coastal oceans and seaside resort areas. This paper presents a method for coastal marine debris mapping using satellite images from multiple satellite platforms. We carry out a pilot project in association with a local government to collect in-situ measurements of debris deposited on beaches and download the coincident satellite images to identify the marine debris. We propose to study the detection of marine debris on land and in the coastal ocean with various sources of satellite imagery as a way to increase the revisit frequency. High temporal resolution data can provide an agile estimation of the resources required to mitigate the pollution accumulation on the shoreline. A major challenge of monitoring specific areas from optical satellite images is the obscuration by cloud cover, which makes it decrease the sampling frequency. To get a handle on this problem and establish high-fidelity model, we acquired the greatest number of satellite images from a variety of platforms including high temporal-resolution imagery provided by small satellite constellation programs. We first established our method using entropy of the segmentation model output on marine debris mapping in coastal areas using WorldView images provided by MAXAR corp. Then we extended the pipeline to other small satellite images using unsupervised domain adaptation techniques. We showed that the spatial representation of the segmentation map is greatly improved by the domain adaptation techniques. Whereas some dataset still requires more data samples and additional quantitative analysis, we confirmed the compatibility of the segmentation output to the established pipeline using entropy metrics to estimate the accumulation density of the debris. This analysis shows the robust capability to be able to apply the pipeline to different types of satellite images, which can be also applied in other remote sensing applications

I Can Parse You: Grammars for Dialogs

Humans and computers increasingly converse via natural language. Those conversations are moving from today\u27s simple question answering and command-and-control to more complex dialogs. Developers must specify those dialogs. This paper explores how to assist developers in this specification. We map out the staggering variety of applications for human-computer dialogs and distill it into a catalog of flow patterns. Based on that, we articulate the requirements for dialog programming models and offer our vision for satisfying these requirements using grammars. If our approach catches on, computers will soon parse you to better assist you in your daily life

Arctic underwater noise transients from sea ice deformation: characteristics, annual time series, and forcing in Beaufort Sea

International audienceA 13-month time series of Arctic Ocean noise from the marginal ice zone of Eastern Beaufort Sea is analyzed to detect under-ice acoustic transients isolated from ambient noise with a dedicated algorithm. Noise transients due to ice cracking, fracturing, shearing, and ridging are sorted out into 3 categories: broadband impulses, frequency modulated (FM) tones, and high-frequency broadband noise. Their temporal and acoustic characteristics over the 8-month ice covered period, from November 2005 to mid-June 2006, are presented and their generation mechanisms are discussed. Correlations analyses showed that the occurrence of these ice transients responded to large-scale ice motion and deformation rates forced by meteorological events, often leading to opening of large-scale leads at main discontinuities in the ice cover. Such a sequence, resulting in the opening of a large lead, hundreds by tens km in size, along the margin of landfast ice and multiyear ice plume in Beaufort-Chukchi seas is detailed. These ice transients largely contribute to the soundscape properties of the Arctic Ocean, for both its ambient and total noise components. Some FM tonal transients can be confounded with marine mammal songs, especially when they are repeated, with periods similar to wind generated waves

Real-Time Effective Stress Evaluation in Shales: Pore Pressure and Permeability Estimation.

In this dissertation, a general method to determine the vertical effective stress in shales while drilling is developed. The concept is applied to the development of a model restricted to sodium smectitic shales, which are interpreted using Measurement-While-Drilling (MWD) resistivity data. Effective stress is introduced as the key parameter in the evaluation of petrophysical properties of shales, which provides a wide range of applications to the method. The model comprises two interpretation modules: an electrical module converts shale resistivity into porosity using a new formation factor relationship adapted from previous work, and a mechanical module relates porosity to void ratio using the one-dimensional compression theory. This approach eliminates the use of normal trends and allows a true real-time interpretation. Most of the advantages of the new model relative to conventional techniques result from the modular approach, which also leaves room for future improvements. In particular, the electrical module can be replaced by any other algorithm capable of providing shale porosity. Two applications are described. The first application allows the real-time evaluation of pore pressure, which is obtained from effective vertical stress using Terzaghi\u27s relationship. The model lends itself particularly well to field implementation. It proved extremely versatile in a variety of drilling environments, including exploration drilling, and more accurate than conventional methods during field tests. The second application provides in situ shale permeability estimates using correlations between permeability and effective stress. A new experimental procedure is suggested to develop such correlations. The effective stress concept appeared to be a powerful interpretation tool in the study of shales, and it is suggested that generalized effective stress logs be developed and used routinely in the evaluation of saturated porous media