A probable Milli-Parsec Supermassive Binary Black Hole in the Nearest Quasar Mrk 231

Supermassive binary black holes (BBHs) are unavoidable products of galaxy mergers and are expected to exist in the cores of many quasars. Great effort has been made during the past several decades to search for BBHs among quasars; however, observational evidence for BBHs remains elusive and ambiguous, which is difficult to reconcile with theoretical expectations. In this paper, we show that the distinct optical-to-UV spectrum of Mrk 231 can be well interpreted as emission from accretion flows onto a BBH, with a semimajor axis of ~590AU and an orbital period of ~1.2 year. The flat optical and UV continua are mainly emitted from a circumbinary disk and a mini-disk around the secondary black hole (BH), respectively; and the observed sharp drop off and flux deficit at wavelength lambda ~ 4000-2500 Angstrom is due to a gap (or hole) opened by the secondary BH migrating within the circumbinary disk. If confirmed by future observations, this BBH will provide a unique laboratory to study the interplay between BBHs and accretion flows onto them. Our result also demonstrates a new method to find sub-parsec scale BBHs by searching for deficits in the optical-to-UV continuum among the spectra of quasars.Comment: a typo in equation (2) and also in equation (5) of the Appendix is fixed; 9 pages, 7 figure

Organizational, Technological, and Environmental Determinants of Electronic Commerce Adoption in Small and Medium Enterprises in Taiwan

In the Internet age, the development of electronic commerce (EC) was considered a major indicator of the overall competitiveness of organizations. Moreover, the EC marketing channel can bring customers more benefits, such as greater shopping convenience and potentially lower prices. In Taiwan, small and medium enterprises (SMEs) represent 98% of the total number of business. Today, most SMEs were forced to adopt EC by their major suppliers and value chain partners in order to carry out business processes more efficiently. Hence, the purpose of this study is to seek the determinants of the extent of EC adoption by SMEs in Taiwan. This study presents a framework based on Tornatzky and Fleischer\u27s (1990) OTE model that includes organizational context, technological context, and environmental context, which have been widely used to examine the factors that influence organizational technology adoption. According to the OTE model, the research model of this study identified nine determinants, including (1) organizational size, (2) CEOs\u27 attitudes toward EC adoption, (3) CEOs\u27 innovativeness, (4) CEOs\u27 technology knowledge, (5) CEOs\u27 perceptions of EC on relative advantages, (6) CEOs\u27 perceptions of EC on compatibility, (7) CEOs\u27 perceptions of EC on complexity, (8) information intensity, and (9) competition intensity. A quantitative, correlational, non-experimental and explanatory research design based on a questionnaire survey was used to collect data, test hypotheses, and answer research questions in this study. 1,500 CEOs of Taiwanese SMEs were randomly selected from the database of E-Volunteer and invited to participate via email on a hyper-link provided to the survey web site. A total of 219 usable questionnaires were obtained for data analysis. The results of this study indicated that all three contexts were important in the decision of EC adoption by Taiwanese SMEs. The findings also supported significance of five determinants that had a positive relationship with the extent of EC adoption. These determinants were organizational size and CEOs\u27 attitudes toward EC adoption, CEOs\u27 perceptions of EC on relative advantage and compatibility, and information intensity. No statistically significant relationship with the extent of EC adoption was established for CEOs\u27 technology knowledge, CEOs\u27 perception of EC on complexity, and competition intensity. This study may not only expand the current body of EC knowledge, but also contribute to the knowledge of CEOs concerning SMEs, EC consultants, suppliers or value chain partners, and government agencies

Computer-aided design of bevel gear tooth surfaces

This paper presents a computer-aided design procedure for generating bevel gears. The development is based on examining a perfectly plastic, cone-shaped gear blank rolling over a cutting tooth on a plane crown rack. The resulting impression on the plastic gear blank is the envelope of the cutting tooth. This impression and envelope thus form a conjugate tooth surface. Equations are presented for the locus of points on the tooth surface. The same procedures are then extended to simulate the generation of a spiral bevel gear. The corresponding governing equations are presented

Deep Learning for Audio Signal Processing

Given the recent surge in developments of deep learning, this article provides a review of the state-of-the-art deep learning techniques for audio signal processing. Speech, music, and environmental sound processing are considered side-by-side, in order to point out similarities and differences between the domains, highlighting general methods, problems, key references, and potential for cross-fertilization between areas. The dominant feature representations (in particular, log-mel spectra and raw waveform) and deep learning models are reviewed, including convolutional neural networks, variants of the long short-term memory architecture, as well as more audio-specific neural network models. Subsequently, prominent deep learning application areas are covered, i.e. audio recognition (automatic speech recognition, music information retrieval, environmental sound detection, localization and tracking) and synthesis and transformation (source separation, audio enhancement, generative models for speech, sound, and music synthesis). Finally, key issues and future questions regarding deep learning applied to audio signal processing are identified.Comment: 15 pages, 2 pdf figure

Study of Primary and Internal Resonance on 3D Free-Free Double-Section Beam

This work investigates the primary resonance and internal resonance of a double-section beam with cubic nonlinearities. This model can be applied in a wide range of engineering problems, such as rocket and missile structures. Even space technology has been developed for decades; several nonlinear properties deserve further study, especially, for the internal resonance. The method of multiple scales (a perturbation technique) is employed to analyze this nonlinear problem. This study focuses on finding the forcing conditions of this 3D double-section beam to trigger the often-ignored internal resonance or prime resonance in rocket structures. A primary resonance is found on a uniform free-free beam at certain flight speed. The three-to-one internal resonance of the double-section beam occurs within the first and the second modes in the diameter ratio of 1/0.75 with the length ratio of 0.33 or 0.51. The semi-analytical results are verified by the time marching numerical method