13,028 research outputs found
An optimized analytical method for the simultaneous detection of iodoform, iodoacetic acid, and other trihalomethanes and haloacetic acids in drinking water
An optimized method is presented using liquid-liquid extraction and derivatization for the extraction of iodoacetic acid (IAA) and other haloacetic acids (HAA9) and direct extraction of iodoform (IF) and other trihalomethanes (THM4) from drinking water, followed by detection by gas chromatography with electron capture detection (GC-ECD). A Doehlert experimental design was performed to determine the optimum conditions for the five most significant factors in the derivatization step: namely, the volume and concentration of acidic methanol (optimized values = 15%, 1 mL), the volume and concentration of Na2SO4 solution (129 g/L, 8.5 mL), and the volume of saturated NaHCO3 solution (1 mL). Also, derivatization time and temperature were optimized by a two-variable Doehlert design, resulting in the following optimized parameters: an extraction time of 11 minutes for IF and THM4 and 14 minutes for IAA and HAA9; mass of anhydrous Na2SO4 of 4 g for IF and THM4 and 16 g for IAA and HAA9; derivatization time of 160 min and temperature at 40°C. Under optimal conditions, the optimized procedure achieves excellent linearity (R2 ranges 0.9990–0.9998), low detection limits (0.0008–0.2 µg/L), low quantification limits (0.008–0.4 µg/L), and good recovery (86.6%–106.3%). Intra- and inter-day precision were less than 8.9% and 8.8%, respectively. The method was validated by applying it to the analysis of raw, flocculated, settled, and finished waters collected from a water treatment plant in China
A refined invariant subspace method and applications to evolution equations
The invariant subspace method is refined to present more unity and more
diversity of exact solutions to evolution equations. The key idea is to take
subspaces of solutions to linear ordinary differential equations as invariant
subspaces that evolution equations admit. A two-component nonlinear system of
dissipative equations was analyzed to shed light on the resulting theory, and
two concrete examples are given to find invariant subspaces associated with
2nd-order and 3rd-order linear ordinary differential equations and their
corresponding exact solutions with generalized separated variables.Comment: 16 page
Unsupervised Diverse Colorization via Generative Adversarial Networks
Colorization of grayscale images has been a hot topic in computer vision.
Previous research mainly focuses on producing a colored image to match the
original one. However, since many colors share the same gray value, an input
grayscale image could be diversely colored while maintaining its reality. In
this paper, we design a novel solution for unsupervised diverse colorization.
Specifically, we leverage conditional generative adversarial networks to model
the distribution of real-world item colors, in which we develop a fully
convolutional generator with multi-layer noise to enhance diversity, with
multi-layer condition concatenation to maintain reality, and with stride 1 to
keep spatial information. With such a novel network architecture, the model
yields highly competitive performance on the open LSUN bedroom dataset. The
Turing test of 80 humans further indicates our generated color schemes are
highly convincible
Fe-doping induced superconductivity in charge-density-wave system 1T-TaS2
We report the interplay between charge-density-wave (CDW) and
superconductivity of 1-FeTaS ()
single crystals. The CDW order is gradually suppressed by Fe-doping,
accompanied by the disappearance of pseudogap/Mott-gap as shown by the density
functional theory (DFT) calculations. The superconducting state develops at low
temperatures within the CDW state for the samples with the moderate doping
levels. The superconductivity strongly depends on within a narrow range,
and the maximum superconducting transition temperature is 2.8 K as . We
propose that the induced superconductivity and CDW phases are separated in real
space. For high doping level (), the Anderson localization (AL) state
appears, resulting in a large increase of resistivity. We present a complete
electronic phase diagram of 1-FeTaS system that shows a
dome-like
Optimal container routing in liner shipping networks considering repacking 20 ft containers into 40 ft containers
© 2017 Shuaian Wang et al. The volume of a 40 ft container is twice as large as that of a 20 ft container. However, the handling cost (loading, unloading, and transshipment) of a 40 ft container is much lower than twice the corresponding handling cost of two 20 ft containers. Enlightened by this observation, we propose a novel container routing with repacking problem in liner shipping, where two 20 ft containers can be repacked to a 40 ft container in order to reduce the handling cost. We develop a mixed-integer linear programming model that formulates the routing decisions and the repacking decisions in a holistic manner. An illustrative example is reported to demonstrate the applicability of the model. Results show that the benefit of repacking is the most significant when containers are transshipped several times
Hot electrons in low-dimensional phonon systems
A simple bulk model of electron-phonon coupling in metals has been
surprisingly successful in explaining experiments on metal films that actually
involve surface- or other low-dimensional phonons. However, by an exact
application of this standard model to a semi-infinite substrate with a free
surface, making use of the actual vibrational modes of the substrate, we show
that such agreement is fortuitous, and that the model actually predicts a
low-temperature crossover from the familiar T^5 temperature dependence to a
stronger T^6 log T scaling. Comparison with existing experiments suggests a
widespread breakdown of the standard model of electron-phonon thermalization in
metals
Bus travel time reliability analysis: A case study
The travel time reliability of buses has become increasingly important for public transit companies. In this study, a novel approach is proposed to evaluate and analyse the travel time reliability of bus services provided by TransLink in Queensland, Australia. In view of their stochastic features, the two components of travel time-dwell time and driving time-are represented by discrete distributed and normally distributed random variables respectively. Accordingly, the travel time could be described by Gaussian mixture models. Based on the proposed model, impact analysis shows that bus line reliability would increase by around 15% if onboard top-up for 'go cards' (electronic tickets) was not offered by TransLink. It was found that not providing this top-up method would not significantly harm the benefit of go card users, but it would substantially increase the total social benefit thanks to improved bus line reliability
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