ABSTRACT
Using a stainless shadow mask combined with a magnetron-ion-assisted deposition (IAD) sputtering system, we investigate the surface morphologies and optical properties of microfilms. Optimal color-filter (CF) coating microfilms with niobium pent-oxide (Nb2O5)/silicon dioxide (SiO2) multilayers on a hard polycarbonate (HPC) substrate, grown at 85 °C and 50 SCCM oxygen flow, can obtain a fairly uniform thickness (with an average roughness of 0.083 and 0.106 nm respectively for Nb2O5 and SiO2 films) through all positions. On a flexible HPC substrate with the Nb2O5/SiO2 microfilms, meanwhile, the peak transmittances measured in the visible range are 95.70% and 91.47%, respectively, for coatings with and without a shadow mask for this new-tech system. For the optimal CF application with a shadow mask, transmittance on each 100 nm band-pass wavelength is enhanced by 4.04% absolute (blue), 2.96% absolute (green), and 2.12% absolute (red). Moreover, the developed new-tech system not only enhances the quality of the films by achieving smoother and uniform surfaces but also reduces deposition time, thereby improving overall process efficiency. For the with-shadow-mask condition, there is little shift at 50% transmittance (T50%), and high transmittance (~97%) is maintained after high-temperature (200 °C) baking for 12 h. These results are well above the commercial CF standard (larger than 90%) and demonstrate reliability and good durability for flexible optical applications.
ABSTRACT
The existing architectures used in the multiparty audio conferencing systems are typically categorized as either centralized or decentralized. These architectures expose a trade-off between processing latency and system capacity, namely the number of participants. This paper proposes a multiparty audio conferencing system for mobile users to improve the processing latency and system capacity. Instead of using the pure centralized or decentralized architecture, the proposed system adopts a novel cooperation-based architecture, in which only some participants are selected as the central controllers to deal with the tasks such as acoustic echo cancellation, encoding, decoding, mixing and de-mixing. The proposed system also uses a buffer reordering scheme to solve the problems of network jitters and out-of-order packets. This study analyzed the processing latency of the multiparty audio conferencing systems using the existing and proposed architectures. We also implemented these systems on diverse mobile platforms to compare the processing latency and number of participants. Performance evaluation results confirmed that the proposed cooperation-based architecture can not only reduce the processing latency but also support more participants, compared to the existing architectures.
ABSTRACT
The continuous global increase in the number of cars has led to an increase in parking issues, particularly with respect to the search for available parking spaces and finding cars. In this paper, we propose a navigation system for car owners to find their cars in indoor parking garages. The proposed system comprises a car-searching mobile app and a positioning-assisting subsystem. The app guides car owners to their cars based on a “turn-by-turn” navigation strategy, and has the ability to correct the user’s heading orientation. The subsystem uses beacon technology for indoor positioning, supporting self-guidance of the car-searching mobile app. This study also designed a local coordinate system to support the identification of the locations of parking spaces and beacon devices. We used Android as the platform to implement the proposed car-searching mobile app, and used Bytereal HiBeacon devices to implement the proposed positioning-assisting subsystem. We also deployed the system in a parking lot in our campus for testing. The experimental results verified that the proposed system not only works well, but also provides the car owner with the correct route guidance information.
