Relative Price Recommendation: Implementing Category Relations and Price of Products to Map Preference

In an e-commerce setting, a successful recommender system needs to incorporate the needs of consumers based on previous purchases by users. Current recommender systems incorporate different features and images of products to recommend products to consumers. Interestingly, the price of an object is one of the biggest constraints that the user faces before making a purchase. However, there is a research gap in our understanding of how to incorporate price into recommender systems. This thesis explores the price aspect of products and how to incorporate price into a relative price-based recommendation. This work is different from modern approaches that observe the price elasticity and price sensitivity of products and to understand consumer behavior. This thesis will highlight how price as a comparable feature can be used to understand consumer interests and how relative price can be used to help narrow down products a consumer will be interested in. This thesis will initially observe the performance of classic models such as user recommender and latent factor models such as Probabilistic Matrix Factorization. Then I will combine the category of relationships based on an economic theory of substitutes and complements to improve the accuracy of currently used models. This framework will address the issues of the long-tail problem inherent in data distribution. From testing with Amazon review data, it has been observed that my framework can levitate the long-tail problem inherent in the dataset. Combined with previous works on price sensitivity, my framework can be used to explain purchase strategies of consumers along with consumer interest

Photothermal Polymer Nanocomposites of Tungsten Bronze Nanorods with Enhanced Tensile Elongation at Low Filler Contents

We present polymer nanocomposites of tungsten bronze nanorods (TBNRs) and ethylene propylene diene monomers (EPDM). The combination of these components allows the simultaneous enhancement in the mechanical and photothermal properties of the composites at low filler contents. The as-synthesized TBNRs had lengths and diameters of 14.0 +/- 2.4 nm and 2.5 +/- 0.5 nm, respectively, and were capped with oleylamine, which has a chemical structure similar to EPDM, making the TBNRs compatible with the bulk EPDM matrix. The TBNRs absorb a wide range of near-infrared light because of the sub-band transitions induced by alkali metal doping. Thus, the nanocomposites of TBNRs in EPDM showed enhanced photothermal properties owing to the light absorption and subsequent heat emission by the TBNRs. Noticeably, the nanocomposite with only 3 wt% TBNRs presented significantly enhanced tensile strain at break, in comparison with those of pristine EPDM, nanocomposites with 1 and 2 wt % TBNRs, and those with tungsten bronze nanoparticles, because of the alignment of the nanorods during tensile elongation. The photothermal and mechanical properties of these nanocomposites make them promising materials for various applications such as in fibers, foams, clothes with cold weather resistance, patches or mask-like films for efficient transdermal delivery upon heat generation, and photoresponsive surfaces for droplet transport by the thermocapillary effect in microfluidic devices and microengines

Dynamical mean-field theory of Hubbard-Holstein model at half-filling: Zero temperature metal-insulator and insulator-insulator transitions

We study the Hubbard-Holstein model, which includes both the electron-electron and electron-phonon interactions characterized by $U$ and $g$, respectively, employing the dynamical mean-field theory combined with Wilson's numerical renormalization group technique. A zero temperature phase diagram of metal-insulator and insulator-insulator transitions at half-filling is mapped out which exhibits the interplay between $U$ and $g$. As $U$ ($g$) is increased, a metal to Mott-Hubbard insulator (bipolaron insulator) transition occurs, and the two insulating states are distinct and can not be adiabatically connected. The nature of and transitions between the three states are discussed.Comment: 5 pages, 4 figures. Submitted to Physical Review Letter

Non-Stationarity of Streamflow in South Korea: Focus on the Effect on Flood Frequency

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Design and Analysis of LoS MIMO Systems with Uniform Circular Arrays

We consider the design of a uniform circular array (UCA) based multiple-input multiple-output (MIMO) system over line-of-sight (LoS) environments in which array misalignment exists. In particular, optimal antenna placement in UCAs and transceiver architectures to achieve the maximum channel capacity without the knowledge of misalignment components are presented. To this end, we first derive a generic channel model of UCA-based LoS MIMO systems in which three misalignment factors including relative array rotation, tilting and center-shift are reflected concurrently. By factorizing the channel matrix into the singular value decomposition (SVD) form, we demonstrate that the singular values of UCA-based LoS MIMO systems are \textit{independent} of tilting and center-shift. Rather, they can be expressed as a function of the \textit{radii product-to-distance ratio} (RPDR) and the angle of relative array rotation. Numerical analyses of singular values show that the RPDR is a key design parameter of UCA systems. Based on this result, we propose an optimal design method for UCA systems which performs a one-dimensional search of RPDR to maximize channel capacity. It is observed that the channel matrix of the optimally designed UCA system is close to an orthogonal matrix; this fact allows channel capacity to be achieved by a simple zero-forcing (ZF) receiver. Additionally, we propose a low-complexity precoding scheme for UCA systems in which the optimal design criteria cannot be fulfilled because of limits on array size. The simulation results demonstrate the validity of the proposed design method and transceiver architectures.Comment: 13 pages, 10 figures, This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessibl

New applications of THz time-domain spectroscopy

This thesis was conducted to provide new applications to THz time-domain spectroscopy and to test alternative theories of conduction by precisely measuring the complex conductivity of doped silicon from low frequencies to frequencies higher than the plasma frequency and the carrier damping rate. I hope this thesis should be of interest to a wide audience of researchers who use thin film and doped silicon as an optical material at THz frequencies. I would like to sincerely thank Dr. Daniel Grischkowsky, my principal advisor, for his intelligent supervision, constructive guidance, scholarship, and encouragement

Fluid-driven mechanical responses of deformable porous media during two-phase flows: Hele-Shaw experiments and hydro-mechanically coupled pore network modeling

Injecting fluid into a porous material can cause deformation of the pore structure. THis hydromechaniically coupled (i.e. poromechanical) phenomenon plays an essential role in many geological and biological operations across a wide range of scale, from geologic carbon storage, enhanced oil recovery and hydraulic fracturing to the transport of fluids through living cells and tissues, and to fuel cells. In this study, we conducted an experimental and numerical investigation of the hydro-mechanical coupling during fluid flows in porous media at the fundamental pore-scale. First, experimental undertaken to ascertain the effect of the hydro-mechanical coupling for two-phase fluid flows in either deformable or non-deformable porous media. Next, a hydro-mechanically coupled pore network model (HM-PNM) was employed to test a various range of influential parameters. The HM-PNM results were consistent with the experimental observations, including the advancing patterns of fluids and the development of the poroelastic deformation, when the vicious drop was incorporated. The hydromechanical coupling was observed to reduce the inlet pressure required to maintain a constant flow rate, whereas its effects on the pattern of fluid flow was minimal. The interfacial tension alteration also changed the pressure and deformation. The viscosity invading fluid showed significant effects on both the patterns of fluid displacement and mechanical deformations

Multiple Sensor Fusion and Motion Control of Snake Robot Based on Soft-Computing

There are many circumstance limits to human like extreme radioactivity, temperature