A Graph-Based Reinforcement Learning Method with Converged State Exploration and Exploitation

In any classical value-based reinforcement learning method, an agent, despite of its continuous interactions with the environment, is yet unable to quickly generate a complete and independent description of the entire environment, leaving the learning method to struggle with a difficult dilemma of choosing between the two tasks, namely exploration and exploitation. This problem becomes more pronounced when the agent has to deal with a dynamic environment, of which the configuration and/or parameters are constantly changing. In this paper, this problem is approached by first mapping a reinforcement learning scheme to a directed graph, and the set that contains all the states already explored shall continue to be exploited in the context of such a graph. We have proved that the two tasks of exploration and exploitation eventually converge in the decision-making process, and thus, there is no need to face the exploration vs. exploitation tradeoff as all the existing reinforcement learning methods do. Rather this observation indicates that a reinforcement learning scheme is essentially the same as searching for the shortest path in a dynamic environment, which is readily tackled by a modified Floyd-Warshall algorithm as proposed in the paper. The experimental results have confirmed that the proposed graph-based reinforcement learning algorithm has significantly higher performance than both standard Q-learning algorithm and improved Q-learning algorithm in solving mazes, rendering it an algorithm of choice in applications involving dynamic environments

A Computation Model for Nanoantenna-based Solar Cell with High Conversion Efficiency

Build a model of spiral nanoantenna and an antennaarray based solar cell collector. Using Rao-Wilton-Glisson (RWG) basis functions tosimulate the spiral nanoantennas. We calculate the frequency response of the radiationgain as the indicator of receiving bandwidth which is akey factor in conversion efficiency

Data of the Constructivist Practices in the Learning Environment Survey From Engineering Undergraduates: An Exploratory Factor Analysis

This paper presents the dataset of a questionnaire on first-year engineering undergraduates’ perceptions of constructivist practices in the learning environment. The questionnaire with a 5-Likert scale was adapted from previous research. The sample consisted of 293 first-year engineering undergraduates in the southwest region of the United States. The online questionnaire was sent to participants who completed it voluntarily at the end of Fall 2019. A total of 274 of 293 participants completed the questionnaire with a response rate of 93.515%. Exploratory factor analysis was conducted to test the underlying factor structure of the questionnaire, which serves as a good reference for future research

III/V-on-Si MQW lasers by using a novel photonic integration method of regrowth on a bonding template.

Silicon photonics is becoming a mainstream data-transmission solution for next-generation data centers, high-performance computers, and many emerging applications. The inefficiency of light emission in silicon still requires the integration of a III/V laser chip or optical gain materials onto a silicon substrate. A number of integration approaches, including flip-chip bonding, molecule or polymer wafer bonding, and monolithic III/V epitaxy, have been extensively explored in the past decade. Here, we demonstrate a novel photonic integration method of epitaxial regrowth of III/V on a III/V-on-SOI bonding template to realize heterogeneous lasers on silicon. This method decouples the correlated root causes, i.e., lattice, thermal, and domain mismatches, which are all responsible for a large number of detrimental dislocations in the heteroepitaxy process. The grown multi-quantum well vertical p-i-n diode laser structure shows a significantly low dislocation density of 9.5 × 104 cm-2, two orders of magnitude lower than the state-of-the-art conventional monolithic growth on Si. This low dislocation density would eliminate defect-induced laser lifetime concerns for practical applications. The fabricated lasers show room-temperature pulsed and continuous-wave lasing at 1.31 μm, with a minimal threshold current density of 813 A/cm2. This generic concept can be applied to other material systems to provide higher integration density, more functionalities and lower total cost for photonics as well as microelectronics, MEMS, and many other applications

Calibration of YSZ Sensors for the Measurement of Oxygen Concentration in Liquid Pb-Bi Eutectic

Although liquid lead-bismuth eutectic (LBE) is a good candidate for coolant in the subcritical transmutation blanket, it is known to be corrosive to stainless steel, the material of the carrying tubes and containers. Such longterm corrosion problem can be prevented by producing and maintaining a protective oxide layer on the exposed surface of stainless steel. For this purpose, it is required to accurately control the concentration of oxygen dissolved in LBE. Currently, YSZ (Yttria Stabilized Zirconia) oxygen sensors, based on an existing automotive oxygen sensor, with molten bismuth saturated with oxygen as the reference, have been selected for oxygen-concentration measurement. The oxygen concentration difference across the solid electrolyte and the resultant oxygen ion conduction inside the electrolyte establishes an electromagnetic force that is used to measure the ppb level concentration of oxygen dissolved in liquid LBE. A set of calibration curves of voltage vs. temperature ranging from 300 0C to 500 0C under various oxygen concentrations in liquid LBE for the YSZ oxygen sensor has been obtained and is presented in this paper. Although the current calibration strategy using the direct injection of hydrogen and oxygen is still inadequate to determine the oxygen concentration in the system, we have found a good candidate for our purpose, which is varying hydrogen to water steam ratio in the system

What Women and Men Want in Online Product Reviews: Gender Effects on Review Helpfulness Perceptions

While academic researchers have studied online product reviews extensively, gender differences have received little attention in the context of online product reviews. This paper identifies important message features in online product reviews and examines which message features female and male consumers value more in evaluating the helpfulness of online product reviews. We collected data from real-world product reviews on Amazon.com and analyzed the data to test the proposed hypotheses. Based on the data analysis results, we find that, in determining helpfulness of online product reviews, female consumers consider more heavily average paragraph length, negative viewpoints, and inclusion of pictures. However, male consumers value positive viewpoints and usage of point format more in evaluating online product reviews. Based on the findings, important contributions to the literature are discussed

Instrumentation of YSZ oxygen sensor calibration in liquid lead-bismuth eutectic

Liquid lead-bismuth eutectic (LBE), a good candidate for the coolant in the subcritical transmutation blanket, is known to be very corrosive to the stainless steel that transports it. Such a corrosion problem can be prevented by producing and maintaining a protective oxide layer on the exposed surface of the stainless steel. Proper formation of the oxide layer critically depends on the accurate measurement and control of the oxygen concentration in liquid LBE. An oxygen sensor calibration/measurement apparatus has been designed and built to deliberately calibrate an yttria stabilized zirconia (YSZ) oxygen sensor. A detailed description of this system with its main components and their functions is presented. Calibration curves of voltage vs. temperature, ranging from 350°C to 550°C, under various oxygen concentrations in liquid LBE have been obtained for the YSZ oxygen sensors, and are presented and analyzed. The characteristics of this YSZ oxygen sensor are analysed and discussed