Chirped polarization volume grating for wide FOV and high‐efficiency waveguide‐based AR displays

We demonstrate a reflective chirped polarization volume grating as a strong contender for wide field‐of‐view augmented reality display systems. By introducing gradient pitch along the beam propagation direction, the angular bandwidth extends dramatically from 18° to 54° while keeping over 80% average efficiency and 95% peak efficiency.     

Arm movement activity based user authentication in P2P systems

Peer-to-Peer Networking and Applications - User authentication has become an essential security element that enables a wide range of applications in P2P systems for higher security and safety...     

Exploiting spatial-temporal context for trajectory based action video retrieval

Multimedia Tools and Applications - Retrieving videos with similar actions is an important task with many applications. Yet it is very challenging due to large variations across different videos....     

Quantum channel discrimination without entanglement

We address the problem of unambiguous discrimination of quantum channels (UDQC) without entanglement. As our main result, we show that even in the absence of entanglement, partial UDQC (PUDQC) can still be performed—depending on the unknown given channel. We provide a necessary and sufficient condition for PUDQC and put forth a method to perform the PUDQC once the said condition is met. We propose the performance metrics that capture the expected performance of the PUDQC independent of the specific channels to be distinguished. Finally, we perform PUDQC on several qubit channel pairs as concrete examples and derive the proposed performance metrics for these channel pairs.     

Improvement of Shipboard Landing Performance of Fixed-wing UAV Using Model Predictive Control

This paper investigates automatic UAV carrier landing using model predictive control that considers carrier deck motions. With dynamic models of a medium-altitude, long-endurance UAV and an aircraft carrier, the proposed guidance and control approach takes the relative geometry between the UAV and the carrier deck into account for safer shipboard landings. Automatic carrier landing is performed sequentially by two types of control systems. A linear quadratic regulator with an integral term is applied up to a few seconds before touchdown followed by a model predictive controller. At this time, optimal control input sequences over a certain time horizon are calculated in real time by predicting the motions of the carrier deck and the UAV. Numerical simulations are performed for a UAV and a carrier with heave motion to verify the feasibility of the proposed approach.     

Forecasting the volatility of a combined multi‐country stock index using GWMA algorithms

Globalization has increased the volatility of international financial transactions, particularly those related to international stock markets. An increase in the volatility of one country's stock market spreads throughout the globe, affecting other countries' stock markets. In particular, the Dow Jones Industrial Average plays an extremely important role in the international stock market. This paper uses the generally weighted moving average method and data from the Dow Jones Industrial Average, the National Association of Securities Dealers Automated Quotations, Japan's Nikkei 225, the Korea Composite Stock Price Index, and the Hong Kong Hang Seng Index to predict the performance of the Taiwan Capitalization Weighted Stock Index. This paper attempts to find the smallest prediction error using the optimal combination of generally weighted moving average model parameters and combinations of various international stock market data and compares the results to that found using the exponentially weighted moving average model to explore differences between the two types of forecasting models.     

A Calculus of Virtual Community Knowledge Intentions: Anonymity and Perceived Network-Structure

This study investigates the underlying motivational factors of knowledge exchange intentions (intention to obtain and to provide knowledge) within virtual community contexts. Perceived virtual network structures, namely virtual network connectivity (CN) and virtual network closeness (CL), are suggested as the important antecedents of knowledge sharing intentions in the context of virtual knowledge exchange communities. Anonymity (AN), one of the unique characteristics of virtual communities, but controversial due to its multi-faceted effects, is considered in a structural model as a factor having an impact on a virtual network structure. Data collected from participants of virtual communities through online surveys are analyzed using Partial Least Squares (PLS) structural equation modeling (SEM) to empirically test the proposed hypotheses. The results reveal that both CN and CL have a significant impact on both of the knowledge exchange intentions although CL shows an opposite direction of the impact. The results also show that AN has a significant impact on CL as expected but not on CN. Implications of this study may shed some light on better understanding community participants’ intentions to obtain and provide knowledge, along with the impact of anonymity on the perceived network structure.     

Filament formation in lithium niobate memristors supports neuromorphic programming capability

Memristor crossbars are capable of implementing learning algorithms in a much more energy and area efficient manner compared to traditional systems. However, the programmable nature of memristor crossbars must first be explored on a smaller scale to see which memristor device structures are most suitable for applications in reconfigurable computing. In this paper, we demonstrate the programmability of memristor devices with filamentary switching based on LiNbO₃, a new resistive switching oxide. We show that a range of resistance values can be set within these memristor devices using a pulse train for programming. We also show that a neuromorphic crossbar containing eight memristors was capable of correctly implementing an OR function. This work demonstrates that lithium niobate memristors are strong candidates for use in neuromorphic computing.

     

Topological metallic structure design for microwave applications using a modified interpolation scheme

In structural design for microwave applications, metallic structures generate the skin effect that critically affects the performance of microwave devices. In finite element analysis (FEA), highly refined mesh generation is necessary to take the skin effect into account. To avoid the expensive fine meshing and computing process, the condition of the perfect electrical conductor (PEC) or the impedance boundary condition has been generally used in FEA based topology optimization. In this study, we proposed a modified penalization formulation using the shifted sigmoid function for the interpolation of the electric permittivity of conductive materials and applied it to microwave structural design through the phase field design method. The proposed approach is available in case of applications to structural design composed of non-ferromagnetic metals. Based on the derived optimal shape, a simple post-processing scheme is employed only once to determine the clear boundary by eliminating the gray scale area for the purpose of manufacturing feasibility. The validity of the proposed design approach is discussed in three numerical examples allowing the change of the target operation frequency.     

Structural equation modeling of office environment quality,sick building syndrome,and musculoskeletal complaints on aggregate satisfaction of office workers

This study aims to analyze the effects of office environment quality (OEQ), sick building syndrome (SBS), and musculoskeletal complaints on aggregate office satisfaction level using the structural equation. A questionnaire survey targeting 483 office workers of 18 public agencies was conducted and surveyed on workers’ characteristics (gender, age, work experience, work hours, and computer time of day), OEQ satisfaction level (temperature and humidity, lighting, noise, and air quality), SBS frequency (eye, noise, throat, skin, and headache), musculoskeletal complaints intensity (neck, shoulder, arm, wrist, waist, and leg), and aggregate office satisfaction level. As a result of the model using the structural equation, the level of OEQ on temperature and humidity, noise, and air quality directly affect the level of SBS frequency. Also, the OEQ level indirectly affects both musculoskeletal complaints’ intensity and aggregate office satisfaction level via the level of SBS frequency. Thus, providing pleasant office environments can be an effective measure to enhance office workers’ satisfaction, because workers’ levels for musculoskeletal complaints and aggregate office satisfaction depend on OEQ and SBS levels.