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Recently, with the development of renewable energy such as solar power and wind power, the dc grid has garnered attention and the dc circuit breakers essential to the dc grid have been actively studied. The dc solid-state circuit breaker (dc SSCB) can quickly break the fault current within 1 ms compared with a mechanical circuit breaker, which does the same in several tens of milliseconds. The previous thyristor dc SSCB cannot naturally charge the commutation capacitor for fault current breaking, and thus its control of operation is complicated. Thus, this article proposes a new thyristor dc SSCB, which can naturally charge the commutation capacitor without complicated switching operation. It can not only perform the fast breaking of fault current, but also the operating duties of reclosing and rebreaking. The operating characteristics of the proposed dc SSCB are verified by the experimental results. [ABSTRACT FROM AUTHOR]

DC microgrids have received remarkable interest in both the academia and the industry for over a decade, yet the protection of dc microgrids remains as a major challenge. This challenge is rooted in the nonexistence of natural zero-crossing point in dc microgrids which rapidly increase the fault current. In this article, a novel bidirectional dc solid-state circuit breaker (dc SSCB) to reinforce the bidirectional flow of energy which significantly boosts the overall efficiency of the power supply of dc microgrids is presented. The proposed topology can perform the operating duty of reclosing and rebreaking, and the commutation capacitor is charged and recharged naturally without any complex control of the main or auxiliary thyristors, which is considered atypical of existing topologies. A clear and detailed analysis of the operation of the proposed topology is presented. Finally, the experimental results are presented to confirm the effectiveness of the proposed novel bidirectional dc SSCB. [ABSTRACT FROM AUTHOR]

Acoustic-resolution photoacoustic micro-scopy (AR-PAM) is an emerging biomedical imaging modality that combines superior optical sensitivity and fine ultrasonic resolution in an optical quasi-diffusive regime (~1–3 mm in tissues). AR-PAM has been explored for anatomical, functional, and molecular information in biological tissues. Heretofore, AR-PAM systems have suffered from a limited field-of-view (FOV) and/or slow imaging speed, which have precluded them from routine preclinical and clinical applications. Here, we demonstrate an advanced AR-PAM system that overcomes both limitations of previous AR-PAM systems. The new AR-PAM system demonstrates a super wide-field scanning that utilized a 1-axis water-proofing microelectromechanical systems (MEMS) scanner integrated with two linear stepper motor stages. We achieved an extended FOV of 36 × 80 mm2 by mosaicking multiple volumetric images of 36 × 2.5 mm2 with a total acquisition time of 224 seconds. For one volumetric data (i.e., 36 × 2.5 mm2), the B-scan imaging speed over the short axis (i.e., 2.5 mm) was 83 Hz in humans. The 3D volumetric image was also provided by using MEMS mirror scanning along the X-axis and stepper-motor scanning along the Y-axis. The super-wide FOV mosaic image was realized by registering and merging all individual volumetric images. Finally, we obtained multi-plane whole-body in-vivo PA images of small animals, illustrating distinct multi-layered structures including microvascular networks and internal organs. Importantly, we also visualized microvascular networks in human fingers, palm, and forearm successfully. This advanced MEMS-AR-PAM system could potentially enable hitherto not possible wide preclinical and clinical applications. [ABSTRACT FROM AUTHOR]

As part of the effort to develop a superconductive microprocessor, we constructed a rapid single flux quantum (RSFQ) 4-bit arithmetic and logic unit (ALU) in a pipelined structure. To speed up the circuit, we used a forward clocking scheme. The 4-bit ALU consisted of ten RSFQ Half Adders, four 2 × 2 switches, and several D flip-flops. By commutating output ports of the half adder, we were able to produce AND, OR, XOR, and ADD functions. The 4-bit ALU was fabricated using., the Korea Photonics Technology Institute's ten-level 1.0 kA/cm² Nb process. The size of the ALU was 3.0 mm × 1.5 mm, fitting in a 5 mm × 5 mm chip. The fabricated 1-bit ALU block was successfully tested at up to a 40 GHz clock frequency. The complete 4-bit ALU operated correctly at up to a 5 GHz clock frequency. [ABSTRACT FROM AUTHOR]

Presents information on a study which examined a local multipoint distribution service system with parallel concatenated convolutional coding. System model; Performance analysis; Simulation results; Conclusions.

Presents information on a study that analyzed the performance of orthogonal frequency division multiplexing (OFDM)/code division multiple access (CDMA) system with turbo coding and simulated in a multipath fading channel. Description of the system model; Performance analysis; Simulation results; Conclusions.

Focuses on the development of a novel low temperature deposition process, using reactive pulsed dc magnetron sputtering, to deposit thin dielectric films. Description of these dielectric films; Use of quality high dielectric thin films in multi-chip module (MCM) and dynamic random access memory (DRAM) applications; Experiments conducted in this research.

Music listening is a very personal and situational behavior for modern people who always carry smartphones in everyday life. Therefore, contextual information, such as user’s current activity and mood state could be used to greatly improve music recommendations. In this paper, we develop a smartphone-based mobile system that includes two core modules for recognizing human activities and then accordingly recommending music. In the proposed method, a deep residual bidirectional gated recurrent neural network is applied to obtain high activity recognition accuracy from accelerometer signals on the smartphone. In order to improve the performance of tempo-oriented music classification, an ensemble of dynamic classification using a long-term modulation spectrum and sequence classification using a short-term spectrogram is used. Music recommendation is performed using the relationship between the recognized human activities and the music files indexed by tempo-oriented music classification that reflects user preference models in order to achieve high user satisfaction. The results of comprehensive experiments on real data confirm the accuracy of the proposed activity-aware music recommendation framework. [ABSTRACT FROM AUTHOR]

Traffic patterns associated with different primary user (PU) channels may provide different spectral access and energy harvesting opportunities in wireless-powered cognitive radio networks (WP-CRNs). Considering this, we propose traffic-specific optimal spectrum sensing policy such that the expected transmission rate of secondary user (SU) is maximized under the energy causality and PU collision constraints in orthogonal frequency-division multiple access (OFDMA)-based WP-CRN. Toward this, we cluster $N$ subcarriers (subchannels) into $K$ clusters (where $K \leq N$) and derive an optimal energy detection threshold for the SU under each traffic pattern. Using traffic features, we propose an unsupervised and nonparametric classification technique to determine the number of unique traffic patterns $K$ over all subchannels. Then, the traffic patterns are used to predict the idle/busy period statistics for subchannels, based upon which SU identifies harvest and transmit PU subchannels for energy harvesting and data transmission, respectively. We derive an optimal detection threshold based on the harvested energy such that it maximizes the expected transmission rate of SU while protecting PU from collision. We demonstrate the effectiveness of the proposed scheme in terms of rate gains under design constraints and show the optimal detection threshold under various energy arrival rates. [ABSTRACT FROM PUBLISHER]