Effective strategy groups used by readers of Chinese as a foreign language

Second language (L2) reading research suggests that successful reading comprehension usually involves a repertoire of strategies. Although Chinese is considered to be a challenging language for foreign language readers, thus far, few studies have investigated how strategies are orchestrated by readers of Chinese as a foreign language (CFL) to enhance comprehension. This study investigated how L2 Chinese readers grouped multiple strategies to comprehend a Chinese text. Through think-aloud and recall protocols, observations, and interviews, it identified several strategy clusters and pairs that helped adult CFL readers to infer words, monitor comprehension, and segment words successfully. It also revealed interrelations between and among strategies within each cluster and pair. The results showed that successful use of strategies in CFL reading usually involves context and multiple linguistic cues. In addition, vocabulary and grammar knowledge play important roles in CFL readers’ use of reading strategies

Maxwell-Hydrodynamic Model for Simulating Nonlinear Terahertz Generation from Plasmonic Metasurfaces

The interaction between the electromagnetic field and plasmonic nanostructures leads to both the strong linear response and inherent nonlinear behavior. In this paper, a time-domain hydrodynamic model for describing the motion of electrons in plasmonic nanostructures is presented, in which both surface and bulk contributions of nonlinearity are considered. A coupled Maxwell-hydrodynamic system capturing full-wave physics and free electron dynamics is numerically solved with the parallel finite-difference time-domain (FDTD) method. The validation of the proposed method is presented to simulate linear and nonlinear responses from a plasmonic metasurface. The linear response is compared with the Drude dispersion model and the nonlinear terahertz emission from a difference-frequency generation process is validated with theoretical analyses. The proposed scheme is fundamentally important to design nonlinear plasmonic nanodevices, especially for efficient and broadband THz emitters.Comment: 8 pages, 7 figures, IEEE Journal on Multiscale and Multiphysics Computational Techniques, 201

The Nature of IT Firms: A Systemic Literature Review and Analysis

IT firms have grown in economic importance in the last few decades. It is the interest of both practitioners and researchers across a range of business management and information system disciplines. Having conducted a systemic literature review, we proposed a new conceptual definition and conceptual frameworks which together provides a deeper understanding of the essence of “IT firms”. The definition we proposed of IT firm offers a way forward for identification of IT firms with increased understanding and a clear boundary. The conceptual framework synthesized the characteristic dimensions of IT firms. It not only improves current understanding of IT firms but also provides a solid foundation for further studies of IT firms. The types of IT firms developed in this paper offers a means of classifying different IT firms. The IT firm development framework in relation to innovation focus and improvisational capabilities not only advances understanding about IT firms, but also provides further research opportunities towards empirical testing and knowledge building. The insights discovered in the paper are also useful for business practitioners in strategy and consulting. The frameworks provide useful knowledge and advice for IT firms within the industry

Full Hydrodynamic Model of Nonlinear Electromagnetic Response in Metallic Metamaterials

Applications of metallic metamaterials have generated significant interest in recent years. Electromagnetic behavior of metamaterials in the optical range is usually characterized by a local-linear response. In this article, we develop a finite-difference time-domain (FDTD) solution of the hydrodynamic model that describes a free electron gas in metals. Extending beyond the local-linear response, the hydrodynamic model enables numerical investigation of nonlocal and nonlinear interactions between electromagnetic waves and metallic metamaterials. By explicitly imposing the current continuity constraint, the proposed model is solved in a self-consistent manner. Charge, energy and angular momentum conservation laws of high-order harmonic generation have been demonstrated for the first time by the Maxwell-hydrodynamic FDTD model. The model yields nonlinear optical responses for complex metallic metamaterials irradiated by a variety of waveforms. Consequently, the multiphysics model opens up unique opportunities for characterizing and designing nonlinear nanodevices.Comment: 11 pages, 14 figure

Hybrid Beamforming via the Kronecker Decomposition for the Millimeter-Wave Massive MIMO Systems

Despite its promising performance gain, the realization of mmWave massive MIMO still faces several practical challenges. In particular, implementing massive MIMO in the digital domain requires hundreds of RF chains matching the number of antennas. Furthermore, designing these components to operate at the mmWave frequencies is challenging and costly. These motivated the recent development of hybrid-beamforming where MIMO processing is divided for separate implementation in the analog and digital domains, called the analog and digital beamforming, respectively. Analog beamforming using a phase array introduces uni-modulus constraints on the beamforming coefficients, rendering the conventional MIMO techniques unsuitable and call for new designs. In this paper, we present a systematic design framework for hybrid beamforming for multi-cell multiuser massive MIMO systems over mmWave channels characterized by sparse propagation paths. The framework relies on the decomposition of analog beamforming vectors and path observation vectors into Kronecker products of factors being uni-modulus vectors. Exploiting properties of Kronecker mixed products, different factors of the analog beamformer are designed for either nulling interference paths or coherently combining data paths. Furthermore, a channel estimation scheme is designed for enabling the proposed hybrid beamforming. The scheme estimates the AoA of data and interference paths by analog beam scanning and data-path gains by analog beam steering. The performance of the channel estimation scheme is analyzed. In particular, the AoA spectrum resulting from beam scanning, which displays the magnitude distribution of paths over the AoA range, is derived in closed-form. It is shown that the inter-cell interference level diminishes inversely with the array size, the square root of pilot sequence length and the spatial separation between paths.Comment: Submitted to IEEE JSAC Special Issue on Millimeter Wave Communications for Future Mobile Networks, minor revisio