Search results for "Spectral slope"

A comprehensive characterization of ice nucleation by three different types of cellulose particles immersed in water: lessons learned and future rese…

2018

We present the laboratory results of immersion freezing efficiencies of cellulose particles at supercooled temperature (T) conditions. Three types of chemically homogeneous cellulose samples are used as surrogates that represent supermicron and submicron ice nucleating plant structural polymers. These samples include micro-crystalline cellulose (MCC), fibrous cellulose (FC) and nano-crystalline cellulose (NCC). Our experimental data show that particles resembling the MCC lab particle occur also in the atmosphere. Our immersion freezing dataset includes data from various ice nucleation measurement techniques available at seventeen different institutions, including nine dry dispersion and ele…

Cloud phase identification of Arctic boundary-layer clouds from airborne spectral reflection measurements: test of three approaches

2008

Abstract. Arctic boundary-layer clouds were investigated with remote sensing and in situ instruments during the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR) campaign in March and April 2007. The clouds formed in a cold air outbreak over the open Greenland Sea. Beside the predominant mixed-phase clouds pure liquid water and ice clouds were observed. Utilizing measurements of solar radiation reflected by the clouds three methods to retrieve the thermodynamic phase of the cloud are introduced and compared. Two ice indices IS and IP were obtained by analyzing the spectral pattern of the cloud top reflectance in the near infrared (1500–1800 nm wavelength) spectral range whi…

Stress Detection from Speech Using Spectral Slope Measurements

2018

Automatic detection of emotional stress is an active research domain, which has recently drawn increasing attention, mainly in the fields of computer science, linguistics, and medicine. In this study, stress is automatically detected by employing speech-derived features. Related studies utilize features such as overall intensity, MFCCs, Teager Energy Operator, and pitch. The present study proposes a novel set of features based on the spectral tilt of the glottal source and of the speech signal itself. The proposed features rely on the Probability Density Function of the estimated spectral slopes, and consist of the three most probable slopes from the glottal source, as well as the correspon…

2019

Abstract. We present the laboratory results of immersion freezing efficiencies of cellulose particles at supercooled temperature ( T) conditions. Three types of chemically homogeneous cellulose samples are used as surrogates that represent supermicron and submicron ice-nucleating plant structural polymers. These samples include microcrystalline cellulose (MCC), fibrous cellulose (FC) and nanocrystalline cellulose (NCC). Our immersion freezing dataset includes data from various ice nucleation measurement techniques available at 17 different institutions, including nine dry dispersion and 11 aqueous suspension techniques. With a total of 20 methods, we performed systematic accuracy and precis…

Effects of dissolved organic matter from a eutrophic lake on the freely dissolved concentrations of emerging organic contaminants

2014

The authors studied the effects of dissolved organic matter (DOM) on the bioavailability of bisphenol A (BPA) and chloramphenicol by measuring the freely dissolved concentrations of the contaminants in solutions containing DOM that had been isolated from a mesocosm in a eutrophic lake. The abundance and aromaticity of the chromophoric DOM increased over the 25-d mesocosm experiment. The BPA freely dissolved concentration was 72.3% lower and the chloramphenicol freely dissolved concentration was 56.2% lower using DOM collected on day 25 than using DOM collected on day 1 of the mesocosm experiment. The freely dissolved concentrations negatively correlated with the ultraviolent absorption coef…

Selective incorporation of dissolved organic matter (DOM) during sea ice formation

2013

This study investigated the incorporation of DOM from seawater into >2 day-old sea ice in tanks filled with seawater alone or amended with DOM extracted from the microalga, Chlorella vulgaris. Optical properties, including chromophoric DOM (CDOM) absorption and fluorescence, as well as concentrations of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), dissolved carbohydrates (dCHOs) and dissolved uronic acids (dUAs) were measured. Enrichment factors (EFs), calculated from salinity-normalized concentrations of DOM in bulk ice, brine and frost flowers relative to under-ice water, were generally >1. The enrichment factors varied for different DOM fractions: EFs were the lowest fo…