Structure, Rheology and Optical Properties of Plasmonic Fluids

Fluids with tunable optical and rheological properties are of fundamental and practical interest. They can be easily processed to manufacture thin films and interfaces for applications such as molecular detection and light trapping in photovoltaics. Cationic surfactants such as cetyl-trimethylammonium bromide have the ability to self assemble with metallic nanoparticles to form a corona or a double-layer vesicular structure. These structures upon further interaction with wormlike micelle fragments are hypothesized to form micelle-nanoparticle elastic networks. In this dissertation, solution phase self-assembly is utilized to uniformly distribute various metallic nanoparticles to produce stable multicomponent plasmonic fluids with remarkable color uniformity. The optical properties of the fluids can be robustly tuned by varying the species, concentration, size and/or shape of the nanoparticles. Multicomponent plasmonic fluids capable of broadband absorption of visible light are produced via the self-assembly route. Small angle X-ray scattering and rheological studies suggest that the nanoparticles are incorporated into the wormlike micelle network to form a more compact double network. These fluids exhibit rich rheological behavior depending on the nanoparticle concentration and the salt to surfactant molar ratio. Specifically, non-monotonic dependence of zero shear viscosity on nanoparticle concentration, rheopexy, shear thickening, shear banding and shear thinning are observed. The fluids exhibit enhanced viscoelasticity upon the addition of more nanoparticles. The mechanical, rheological and optical properties of plasmonic fluids greatly depend upon the temperature due to the structural changes of the micellar solutions. The application of plasmonic fluids to efficient light trapping in photovoltaic cells, plasmon-enhanced microalgal growth and optofluidic devices have been designed and demonstrated in this dissertation

SURGE: Continuous Detection of Bursty Regions Over a Stream of Spatial Objects

With the proliferation of mobile devices and location-based services, continuous generation of massive volume of streaming spatial objects (i.e., geo-tagged data) opens up new opportunities to address real-world problems by analyzing them. In this paper, we present a novel continuous bursty region detection problem that aims to continuously detect a bursty region of a given size in a specified geographical area from a stream of spatial objects. Specifically, a bursty region shows maximum spike in the number of spatial objects in a given time window. The problem is useful in addressing several real-world challenges such as surge pricing problem in online transportation and disease outbreak detection. To solve the problem, we propose an exact solution and two approximate solutions, and the approximation ratio is $\frac{1-\alpha}{4}$ in terms of the burst score, where $\alpha$ is a parameter to control the burst score. We further extend these solutions to support detection of top-$k$ bursty regions. Extensive experiments with real-world data are conducted to demonstrate the efficiency and effectiveness of our solutions

N′-(5-Bromo-2-hydroxy­benzyl­idene)-4-chloro­benzohydrazide

The title Schiff base, C14H10BrClN2O2, exists in a trans configuration with respect to the C=N bond and the dihedral angle between the two benzene rings is 0.8 (2)°. There is an intra­molecular O—H⋯N hydrogen bond in the mol­ecule, which generates an S(6) loop. In the crystal, inter­molecular N—H⋯O hydrogen bonds link adjacent mol­ecules into extended chains propagating along the c-axis direction

Direct observation of the ground state of a 1/3 quantum magnetization plateau in SrMn3_3P4_4O14_{14} using neutron diffraction measurements

We can directly investigate the ground state in magnetization-plateau fields (plateau ground state) using neutron diffraction measurements. We performed neutron diffraction measurements on the spin-5/2 trimer substance SrMn$_3$P$_4$O$_{14}$ in magnetization-plateau fields. The integrated intensities of magnetic reflections calculated using an expectation value of each spin in a plateau ground state of an isolated-trimer model agree well with those obtained experimentally in the magnetization-plateau fields. We succeeded in direct observation of a plateau ground state in SrMn$_3$P$_4$O$_{14}$

A multi-tone sound absorber based on an array of shunted loudspeakers

© 2018 by the authors. It has been demonstrated that a single shunted loudspeaker can be used as an effective low frequency sound absorber in a duct, but many shunted loudspeakers have to be used in practice for noise reduction or reverberation control in rooms, thus it is necessary to understand the performance of an array of shunted loudspeakers. In this paper, a model for the parallel shunted loudspeaker array for multi-tone sound absorption is proposed based on a modal solution, and then the acoustic properties of a shunted loudspeaker array under normal incidence are investigated using both the modal solution and the finite element method. It was found that each shunted loudspeaker can work almost independently where each unit resonates. Based on the interaction analysis, multi-tone absorbers in low frequency can be achieved by designing multiple shunted loudspeakers with different shunt circuits respectively. The simulation and experimental results show that the normal incidence sound absorption coefficient of the designed absorber has four absorption peaks with values of 0.42, 0.58, 0.80, and 0.84 around 100 Hz, 200 Hz, 300 Hz, and 400 Hz respectively