Multimodal Definition: The Multiplication of Meaning in Electronic Dictionaries

With the popularity of electronic dictionaries, multimodality plays an increasingly important role in lexicography. To broaden the horizons of e-dictionary definitions, this article argues for the establishment of a new term, multimodal definition, as a key component of multimodal lexicography. This term integrates verbal definitions and the complementary multimodal resources from a holistic viewpoint of meaning. In a multimodal definition, a dynamic meaning ecology can be formed, with two critical variables functioning, (semiotic) mode selection and intermodal synergy. In this ecology, meaning expressed verbally can be multiplied in four dimensions: content, form, space and time. Future directions for research are discussed, including dictionary user studies and multimodal corpora. The findings of this article shed light on the construction of a theoretical model for e-lexicography which remains an urgent task in the ongoing digital revolution.Keywords: Multimodality, multimodal definition, multimodal lexicography, e-dictionary, mode selection, intermodal synergy

Radar Waveform Design for Extended Target Recognition under Detection Constraints

We address the problem of radar phase-coded waveform design for extended target recognition in the presence of colored Gaussian disturbance. Phase-coded waveforms are selected since they can fully exploit the transmit power with sufficient variability. An important constraint, target detection performance, is considered to meet the practical requirements. The waveform is designed to achieve maximum recognition performance under a control on the achievable signal-to-noise ratio (SNR) of every possible target hypothesis. We formulate the code design in terms of a nonconvex, NP-hard quadratic optimization problem in the cases of both continuous and discrete phases. Techniques based on semidefinite relaxation (SDR) and randomization are proposed to approximate the optimal solutions. Simulation results show that the recognition performance and the detection requirements are well balanced and accurate approximations are achieved