Search results for "Dispersion"
showing 10 items of 1101 documents
Kinetic interpretation of influence of sodium chloride concentration and temperature on xanthan gum dispersion flow model
2001
The present study derives a fixed-concentration (0.4%) xanthan gum dispersion flow model for different molar concentrations of sodium chloride (0–0.25M) and different temperatures (20–70°C). The Ostwald–de Waele model is used in all cases. A temperature rise reduces the shear-thinning characteristics of the systems, although the power law index is much less sensitive to changes in temperature when NaCl is added, even in very small amounts. The lowest consistency values correspond to the dispersions formulated in the absence of salt, the highest values are observed for molar values of ≥0.15, and there are decreases in consistency upon raising the temperature in all cases. The viscous behavio…
Elastic properties of CsCN
1983
The temperature dependence of the elastic constants of CsCN exhibiting the CsCl structure was measured with ultrasonic and neutron techniques. The room temperature values were found to bec11=18.8,c12=10.7 andc44=2.95 1010 dyn/cm2. The sound waves inT2g andEg symmetries exhibit anomalous temperature effects which are similar but definitively weaker than those in the NaCl type cyanides. In addition we measured the acoustic phonon dispersion along [100] and [110]. These results are compared with recent molecular dynamics calculations.
Return Dispersion and Cross-Sectional Asset Pricing Anomalies
2015
Recent research finds that cross-sectional return dispersion provides a risk-based explanation for some investment anomalies, including accrual, investment, and momentum strategies. This study extends the analyses of return dispersion to a broad set of anomalies by testing whether the state of return dispersion is associated with anomalous returns. Empirical results for 12 well-known anomalies indicate a robust link between good and bad states of return dispersion and most anomalies. Also, return dispersion helps to explain a number anomalies regardless of their association with investor sentiment. We conclude that market risk related to return dispersion plays an important role in many inv…
Risk-Managed 52-Week High Industry Momentum, Momentum Crashes, and Hedging Macroeconomic Risk
2017
This is the first study that investigates the profitability of Barroso and Santa-Clara’s (2015) risk managing approach for George and Hwang’s (2004) 52-week high momentum strategy in an industrial portfolio setting. The findings indicate that risk-managing adds value as the Sharpe ratio increases, and the downside risk remarkably decreases. Even after controlling for the spread of the traditional 52-week high industry momentum strategy in association with standard risk-factors, the risk-managed version generates economically and statistically significant payoffs. Notably, the risk-managed strategy is partially explained by changes in cross-sectional return dispersion, whereas the traditiona…
Performances and morphology of polyamide/carbonaceous structures based fibers
2014
In this work the influence of carbonaceous particles with different particle sizes and shapes on the morphology and mechanical performances of polyamide (PA) based fibers was investigated. Graphene nanoplatelets (GNP) are compared with spherical and rod-like carbon fillers such as carbon black (CB) and multiwall carbon nanotubes (MWCNT). The different morphologies of the particles control their dispersion and their alignment in PA fibers upon elongational flow action and play a key role in structure-property relationships.
Taking advantage of the functional synergism between carbon nanotubes and graphene nanoplatelets to obtain polypropylene-based nanocomposites with en…
2020
Carbon Nanotubes (CNT) and Graphene Nanoplatelets (GNP) were incorporated in Polypropylene (PP) as single filler (CNT=1, 2 and 4 %wt. and GNP=2, 4, and 6 %wt.) and in hybrid form (CNT:GNP weight ratio 2:2, 2:4 and 4:2) using a prototype miniature Twin Screw Extruder (TSE) coupled with a double slit rheological die, in order to assess in-line the extent of nanofiller dispersion and to deliver PP-based nanocomposites with enhanced thermo-oxidative stability. The morphological, electrical and mechanical properties, as well as the resistance to thermal and photo degradation of the composites containing single nanofillers (PP/CNT and PP/GNP) were compared with those of hybrid PP based nanocompos…
On the designing of densely dispersion-managed optical fiber systems for ultrafast optical communication
2003
We present some theoretical and experimental results which suggest the possibility of constructing a non-empirical methodology of designing optical transmission systems with ultra high bit-rate per channel. Theoretically, we present an average dispersion decreasing densely dispersion-managed (A4dm) fiber system, which exhibits many advantages over the densely dispersion-managed fiber system, such as the possibility of transmitting chirp-free Gaussian pulses at 160 Gbit/s per channel over transoceanic distances, with a reduced energy and minimal intra-channel interaction. Experimentally we present generation of a 160-GHz picosecond pulse train at 1550 nm using multiple four-wave mixing tempo…
A fiber-based limiter at 170 Gbit/s for all-optical regeneration
2009
We report the numerical and experimental studies of a spectrally filtered fiber-based optical limiter at 170 Gbit/s. The device, including less than 1 km-long of highly nonlinear optical fiber and a 3 nm-width filter, exhibits good performance at an average input power of 14.5 dBm. No power penalty has been observed and a strong robustness against optical noise has been demonstrated.
Optical spectra beyond the amplifier bandwidth limitation in dispersion-managed mode-locked fiber lasers
2011
We investigate the intracavity pulse dynamics inside dispersionmanaged mode-locked fiber lasers, and show numerically that for a relatively wide range of parameters, pulse compression dynamics in the passive anomalous fiber can be accompanied by a significant enhancement of the spectral width by a factor close to 3. Varying the average cavity dispersion also reveals chaotic dynamics for certain dispersion ranges. The impact of the implementation of an optical output port to tap optimal pulse features is discussed. © 2011 Optical Society of America.