A Deep Learning-Based Chinese Semantic Parser for the Almond Virtual Assistant.

Almond is an extendible open-source virtual assistant designed to help people access Internet services and IoT (Internet of Things) devices. Both are referred to as skills here. Service providers can easily enable their devices for Almond by defining proper APIs (Application Programming Interfaces) for ThingTalk in Thingpedia. ThingTalk is a virtual assistant programming language, and Thingpedia is an application encyclopedia. Almond uses a large neural network to translate user commands in natural language into ThingTalk programs. To obtain enough data for the training of the neural network, Genie was developed to synthesize pairs of user commands and corresponding ThingTalk programs based on a natural language template approach. In this work, we extended Genie to support Chinese. For 107 devices and 261 functions registered in Thingpedia, 649 Chinese primitive templates and 292 Chinese construct templates were analyzed and developed. Two models, seq2seq (sequence-to-sequence) and MQAN (multiple question answer network), were trained to translate user commands in Chinese into ThingTalk programs. Both models were evaluated, and the experiment results showed that MQAN outperformed seq2seq. The exact match, BLEU, and F1 token accuracy of MQAN were 0.7, 0.82, and 0.88, respectively. As a result, users could use Chinese in Almond to access Internet services and IoT devices registered in Thingpedia.

Diameter-dependent surface photovoltage and surface state density in single semiconductor nanowires.

Based on single-nanowire surface photovoltage measurements and finite-element electrostatic simulations, we determine the surface state density, N(s), in individual n-type ZnO nanowires as a function of nanowire diameter. In general, N(s) increases as the diameter decreases. This identifies an important origin of the recently reported diameter dependence of the surface recombination velocity, which has been commonly considered to be independent of the diameter. Furthermore, through the determination of the surface carrier lifetime, we suggest that the diameter dependence of the surface state density accounts for the rather abrupt transition from bulk-limited to surface-limited carrier transport over a narrow nanowire diameter regime (~30-40 nm). These findings are supported by the comparison between bulk-limited and surface-dependent minority carrier diffusion lengths measured at various diameters.