Li-Chen Cheng

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In recent years, Collaborative Filtering (CF) has proven to be one of the most successful techniques used in recommendation systems. Since current CF systems estimate the ratings of not-yet-rated items based on other items’ ratings, these CF systems fail to recommend products when users’ preferences are not expressed in numbers. In many practical(More)
1567-4223/$ see front matter 2011 Elsevier B.V. A doi:10.1016/j.elerap.2011.06.005 ⇑ Corresponding author. Tel.: +886 2 23111531x38 E-mail address: lijencheng@csim.scu.edu.tw (L.-C. As the profit margins of 3G mobile network operators gradually decline, and market competition becomes increasingly intensive, they must develop rich and diverse varieties of(More)
This paper presents a novel control method for a current-fed full-bridge inverter actuating an ultrasonic piezoelectric transducer (PT). In the conventional ultrasonic detection system, the PT has maximum transmitting gain at its series resonance frequency while having maximum receiving gain at its parallel resonance frequency. With the proposed approach,(More)