An Efficient Method for Generating Synthetic Data for Low-Resource Machine Translation – An empirical study of Chinese, Japanese to Vietnamese Neural Machine Translation

Data sparsity is one of the challenges for low-resource language pairs in Neural Machine Translation (NMT). Previous works have presented different approaches for data augmentation, but they mostly require additional resources and obtain low-quality dummy data in the low-resource issue. This paper proposes a simple and effective novel for generating synthetic bilingual data without using external resources as in previous approaches. Moreover, some works recently have shown that multilingual translation or transfer learning can boost the translation quality in low-resource situations. However, for logographic languages such as Chinese or Japanese, this approach is still limited due to the differences in translation units in the vocabularies. Although Japanese texts contain Kanji characters that are derived from Chinese characters, and they are quite homologous in sharp and meaning, the word orders in the sentences of these languages have a big divergence. Our study will investigate these impacts in machine translation. In addition, a combined pre-trained model is also leveraged to demonstrate the efficacy of translation tasks in the more high-resource scenario. Our experiments present performance improvements up to +6.2 and +7.8 BLEU scores over bilingual baseline systems on two low-resource translation tasks from Chinese to Vietnamese and Japanese to Vietnamese

Incidences between points and generalized spheres over finite fields and related problems

Let $\mathbb{F}_q$ be a finite field of $q$ elements where $q$ is a large odd prime power and $Q =a_1 x_1^{c_1}+...+a_dx_d^{c_d}\in \mathbb{F}_q[x_1,...,x_d]$, where $2\le c_i\le N$, $\gcd(c_i,q)=1$, and $a_i\in \mathbb{F}_q$ for all $1\le i\le d$. A $Q$-sphere is a set of the form $\lbrace x\in \mathbb{F}_q^d | Q(x-b)=r\rbrace$, where $b\in \mathbb{F}_q^d, r\in \mathbb{F}_q$. We prove bounds on the number of incidences between a point set $\mathcal{P}$ and a $Q$-sphere set $\mathcal{S}$, denoted by $I(\mathcal{P},\mathcal{S})$, as the following. $$| I(\mathcal{P},\mathcal{S})-\frac{|\mathcal{P}||\mathcal{S}|}{q}|\le q^{d/2}\sqrt{|\mathcal{P}||\mathcal{S}|}.$$ We prove this estimate by studying the spectra of directed graphs. We also give a version of this estimate over finite rings $\mathbb{Z}_q$ where $q$ is an odd integer. As a consequence of the above bounds, we give an estimate for the pinned distance problem. In Sections $4$ and $5$, we prove a bound on the number of incidences between a random point set and a random $Q$-sphere set in $\mathbb{F}_q^d$. We also study the finite field analogues of some combinatorial geometry problems, namely, the number of generalized isosceles triangles, and the existence of a large subset without repeated generalized distances.Comment: to appear in Forum Mat

A Robust Control for Five-level Inverter Based on Integral Sliding Mode Control

This paper presents a new control strategy for cascaded H-bridge five-level inverter (CHB-5LI) based on the novel sliding mode control (NSMC). The proposed method can generate pulse-width modulation (PWM) without using conventional modulation techniques based on carrier waves. With the proposed NSMC technique, the PWM pulses can be obtained by the control signal u(t) from the output of the sliding mode controller and the levels of comparison. To eliminate the chattering and increase the speed convergence of the controller, the integral sliding-mode surface combined with a first-order low-pass filter (LPF) is used. The stability of the control system is validated by Lyapunov theory. The simulation and experimental results show that the proposed NSMC method has strong robustness, and better performance for multi-level inverter control systems with low total harmonic distortion, Common-Mode (CM) voltage reduction, switching frequency diminution, and less switching loss

A Robust Control for Five-level Inverter Based on Integral Sliding Mode Control

This paper presents a new control strategy for cascaded H-bridge five-level inverter (CHB-5LI) based on the novel sliding mode control (NSMC). The proposed method can generate pulse-width modulation (PWM) without using conventional modulation techniques based on carrier waves. With the proposed NSMC technique, the PWM pulses can be obtained by the control signal u(t) from the output of the sliding mode controller and the levels of comparison. To eliminate the chattering and increase the speed convergence of the controller, the integral sliding-mode surface combined with a first-order low-pass filter (LPF) is used. The stability of the control system is validated by Lyapunov theory. The simulation and experimental results show that the proposed NSMC method has strong robustness, and better performance for multi-level inverter control systems with low total harmonic distortion, Common-Mode (CM) voltage reduction, switching frequency diminution, and less switching loss