Essays on price-setting in online markets

This thesis includes three empirical papers focusing on pricing behaviour of online sellers. The first chapter investigates the impact of goods quality on pricing decision. We find the positive impact of product quality on the frequency of price changes. This impact can be explained with the higher search intensity of high-quality products, which put pressure on sellers to update their prices more frequently. Additionally, products with better quality have larger size of price changes due to the expensive quality premium which provides more room for sellers to adjust their prices. The analysis also reveals that the releases of successor products using new technology increase the frequency as well as the size of price adjustments of existing products. The second chapter explores price-setting after a foreign supply shock, which in turn affected the inventory level of domestic sellers. In this chapter, we employ the 2011 Thailand flood as an exogenous hard drive supply shock which severely affected inventory of U.S. sellers to examine sellers’ post-shock behaviour and the transmission of shock to relevant markets. We find that hard drive sellers raised their prices instantly in response to the shock suggesting that prices are flexible to sectoral shocks. This result shows little support for pricing models with “fear of customer anger” which suggest that sellers would not raise prices in response to such shock due to fear of damaging the relationship with customers. Further analysis provides evidence that the shock was transmitted via supply chains to other product types but the spillover is delayed and mitigated as the shock propagates through production networks. The third chapter uncovers the impact of seller reputation on pricing decision by using the rating score of sellers rated by customers in the online market. The results show that nonprice factors (such as seller reputation, selling effort, communication, service quality, and delivery lags), which are reflected by seller rating scores, play important roles in price-setting. In particular, sellers with higher rating scores tend to increase their prices more and decrease their prices less often. This result suggests that sellers can exploit their high-reputation to gain positive price premium in online markets and shows little support for pricing models with “customer anger”. Furthermore, besides the reputation level, the variations of seller reputation (standard deviation and frequency of increases/decreases of seller rating scores) are also important in price-setting as well as in explaining the price differences across sellers within a product. The findings contribute to the large literature on price stickiness and price dispersion by uncovering the impact of seller reputation and its variations on price stickiness as well as price dispersion. This chapter is also closely related to the literature on reputation mechanism in the online market

Flexible Pavement Life Cycle Cost Analysis by Using Monte-Carlo Method and the Suggestions for Developing Countries

Flexible road pavement plays an essential role in developing an effective, economic, and safe operation road network of any country. In Vietnam, a developing country, the selection of a suitable flexible pavement structure is always a challenge due to fiscal limitations. The traditional determinant method (TDM) by which pavement structures are selected mainly on the basis of initial construction costs and traffic load has been used for many years in the nation. This paper presents the use of Monte Carlo simulation to analyze the entire flexible pavement life cycle cost. Data including initial and maintenance costs and road user costs were collected from several different types of existing flexible pavement in Nghe An province, Vietnam. Random variations of several main inputs were explored in order to develop density distribution functions. These functions then were used as the bases for Monte Carlo simulation. One million simulation runs were implemented and the Net Present Values (NPVs) among pavement types were compared under the light of risk analysis. Research results showed that TDM method provided bias and uncertain results compared to that of Monte Carlo one. In terms of long- term pavement performance, a low-cost pavement structure should not always be considered as a wise selection. Some other suggestions for a developing country as Vietnam were also included

License Plate Recognition Based On Multi-Angle View Model

In the realm of research, the detection/recognition of text within images/videos captured by cameras constitutes a highly challenging problem for researchers. Despite certain advancements achieving high accuracy, current methods still require substantial improvements to be applicable in practical scenarios. Diverging from text detection in images/videos, this paper addresses the issue of text detection within license plates by amalgamating multiple frames of distinct perspectives. For each viewpoint, the proposed method extracts descriptive features characterizing the text components of the license plate, specifically corner points and area. Concretely, we present three viewpoints: view-1, view-2, and view-3, to identify the nearest neighboring components facilitating the restoration of text components from the same license plate line based on estimations of similarity levels and distance metrics. Subsequently, we employ the CnOCR method for text recognition within license plates. Experimental results on the self-collected dataset (PTITPlates), comprising pairs of images in various scenarios, and the publicly available Stanford Cars Dataset, demonstrate the superiority of the proposed method over existing approaches

An analytical approach to analyze nonlinear dynamic response of eccentrically stiffened functionally graded circular cylindrical shells subjected to time dependent axial compression and external pressure. Part 2: Numerical results and discussion

Based on the classical thin shell theory with the geometrical nonlinearity in von Karman-Donnell sense, the smeared stiffener technique, Galerkin method and an approximate three-term solution of deflection taking into account the nonlinear buckling shape is chosen, the governing nonlinear dynamic equations of eccentrically stiffened functionally graded circular cylindrical shells subjected to time dependent axial compression and external pressure is established in part 1. In this study, the nonlinear dynamic responses are obtained by fourth order Runge-Kutta method and the nonlinear dynamic buckling behavior of stiffened functionally graded shells under linear-time loading is determined by according to Budiansky-Roth criterion. Numerical results are investigated to reveal effects of stiffener, input factors on the vibration and nonlinear dynamic buckling loads of stiffened functionally graded circular cylindrical shells

An analytical approach to analyze nonlinear dynamic response of eccentrically stiffened functionally graded circular cylindrical shells subjected to time dependent axial compression and external pressure. Part 1: Governing equations establishment

Based on the classical thin shell theory with the geometrical nonlinearity in von Karman-Donnell sense, the smeared stiffener technique and Galerkin method, this paper deals with the nonlinear dynamic problem of eccentrically stiffened functionally graded circular cylindrical shells subjected to time dependent axial compression and external pressure by analytical approach. The present novelty is that an approximate three-term solution of deflection taking into account the nonlinear buckling shape is chosen, the nonlinear dynamic second-order differential three equations system is established and the frequency-amplitude relation of nonlinear vibration is obtained in explicit form

Corrosion protection of carbon steel by an epoxy resin containing organically modified clay

This study focusses on the use of montmorillonite clay (MMT) treated with an organic compound (aminotrimethylphosphonic acid (ATMP)) and dispersed in an epoxy resin to improve corrosion protection of carbon steel. X-ray diffraction was performed to verify that the individual silicate layers were separated and dispersed in the epoxy resin. Corrosion resistance of the coated steel was evaluated by electrochemical impedance spectroscopy (EIS) and local electrochemical impedance spectroscopy (LEIS). Three systems were tested: the epoxy clear-coat, the epoxy resin containing 2 wt.% clay and the epoxy resin containing 2 wt.% clay modified byATMP (ATMP-modified clay). From conventional EIS, it was shown that the incorporation of clay or ATMP-modified clay in the epoxy matrix significantly improved the barrier properties of the coating. The corrosion resistance of the carbon steel coated by the epoxy resin containing ATMP-modified clay was higher than that obtained for the system containing non-treated clay. Local electrochemical measurements performed on scratched samples revealed the inhibitive role of ATMP at the carbon steel/coating interface

Light Absorption and Luminescence Properties of the Blend Poly(N-vinylcarbazole)/Poly(N-hexylthiophene)

We have investigated the enhancement absorption light and luminescence properties of the blend conducting polymers using poly(N-vinylcarbazole) and poly(N-hexylthiophene). The optimized material showed a broad absorption in the region of ultra violet to near infra-red and the better of luminescence ability than the pristine conducting polymers. The remarkable improvements in photoluminescences of the blends provide useful information to the application of this material in fabrication of optical – electronic devices.

Sterols isolated from the soft coral sinularia dissecta

Using various chromatographic methods, five sterols, gorgost-4-ene-3-one (1), ergost-4-ene-3-one (2), 24-methyleneergost-4-ene-3-one (3), ergost-4-ene-3,6-dione (4), and 24-methylenecholest-4-ene-3,6-dione (5), were isolated from the methanol extract of the soft coral Sinularia dissecta. Their structures were elucidated by 1D and 2D-NMR experiments and comparison of their NMR data with reported values. These compounds were isolated from S. dissecta for the first time