arXiv subjects

Chunyang Ma

Publications and source records attributed to Chunyang Ma.

6 recordsLinked to original sources

arXiv2025

Flexible mm-Wave Frequency and High-Speed Arbitrary IQ Signal Synthesis by a Photonic System on Chip

Photonics-assisted millimeter-wave bands and terahertz signal generation offer significant advantages over traditional electronic methods by leveraging the inherent benefits of optical components, including broad bandwidth, low power consumption, and minimal insertion loss. This work utilizes a silicon photonic chip in conjunction with a reconfigurable optical frequency comb to demonstrate the synthesis of signals in the millimeter-wave range. The implemented photonic system performs on-chip filtering and modulation, producing high-bandwidth single frequency, multi-frequency, and vector signals suitable for arbitrary IQ signal construction. These results highlight the flexible and reconfigurable capabilities of the proposed approach, providing new perspectives for applications in radio-over-fiber systems and beyond.

physics.optics↗

arXiv2025

CSRM-LLM: Embracing Multilingual LLMs for Cold-Start Relevance Matching in Emerging E-commerce Markets

As global e-commerce platforms continue to expand, companies are entering new markets where they encounter cold-start challenges due to limited human labels and user behaviors. In this paper, we share our experiences in Coupang to provide a competitive cold-start performance of relevance matching for emerging e-commerce markets. Specifically, we present a Cold-Start Relevance Matching (CSRM) framework, utilizing a multilingual Large Language Model (LLM) to address three challenges: (1) activating cross-lingual transfer learning abilities of LLMs through machine translation tasks; (2) enhancing query understanding and incorporating e-commerce knowledge by retrieval-based query augmentation; (3) mitigating the impact of training label errors through a multi-round self-distillation training strategy. Our experiments demonstrate the effectiveness of CSRM-LLM and the proposed techniques, resulting in successful real-world deployment and significant online gains, with a 45.8% reduction in defect ratio and a 0.866% uplift in session purchase rate.

cs.IR↗

arXiv2025

Magnitude-Phase Dual-Path Speech Enhancement Network based on Self-Supervised Embedding and Perceptual Contrast Stretch Boosting

Speech self-supervised learning (SSL) has made great progress in various speech processing tasks, but there is still room for improvement in speech enhancement (SE). This paper presents BSP-MPNet, a dual-path framework that combines self-supervised features with magnitude-phase information for SE. The approach starts by applying the perceptual contrast stretching (PCS) algorithm to enhance the magnitude-phase spectrum. A magnitude-phase 2D coarse (MP-2DC) encoder then extracts coarse features from the enhanced spectrum. Next, a feature-separating self-supervised learning (FS-SSL) model generates self-supervised embeddings for the magnitude and phase components separately. These embeddings are fused to create cross-domain feature representations. Finally, two parallel RNN-enhanced multi-attention (REMA) mask decoders refine the features, apply them to the mask, and reconstruct the speech signal. We evaluate BSP-MPNet on the VoiceBank+DEMAND and WHAMR! datasets. Experimental results show that BSP-MPNet outperforms existing methods under various noise conditions, providing new directions for self-supervised speech enhancement research. The implementation of the BSP-MPNet code is available online\footnote[2]{https://github.com/AlimMat/BSP-MPNet. \label{s1}}

cs.SD↗

arXiv2023

Quasi-invariance of scattering properties of multicellular cyanobacterial aggregates

The radiative/scattering properties of cyanobacterial aggregates are crucial for understanding microalgal cultivation. This study analyzed scattering matrix elements and cross-sections of cyanobacterial aggregates using the discrete dipole approximation (DDA) method. The stochastic random walk approach was adopted to generate a force-biased packing model for multicellular filamentous cyanobacterial aggregates. The effects of shape and size of multicellular cyanobacterial aggregates on their scattering properties were investigated by this work. The possibility of invariance in the scattering properties was explored for cyanobacterial aggregates. The invariance interpretation intuitively represented the radiative property characteristics of the aggregates. The presented results show that the ratios of the matrix elements of cyanobacterial aggregates are nearly shape, size, and wavelength invariant. The extinction and absorption cross-sections (EACSs) per unit volume were shape and approximate size invariance of cyanobacterial aggregates, respectively. The absorption cross-section of aggregates is not merely a volumetric phenomenon for aggregates that exceed a certain size. Furthermore, the absorption cross-sections per unit volume are independent of the volumetric distribution of the microalgae cells. The invariance interpretation presents crucial characteristics of the scattering properties of cyanobacterial aggregates. The existence of invariance greatly improves our understanding of the scattering properties of microalgal aggregates. The scattering properties of microalgal aggregates are the most critical aspects of light propagation in the design, optimization, and operation of photobioreactors.

physics.optics↗

arXiv2020

Determination of the scaling characteristics of time-dependent optical properties of microalgae using electromagnetic scattering

The time-dependent optical properties of microalgae are crucial for light transfer in photobioreactor (PBR) designs. Here, the time-dependent optical properties were derived using electromagnetic scattering theory informed by the experimentally measured optical properties of Chlorella protothecoides. The temporal scaling functions (TSFs) of nearly wavelength-independent absorption and scattering cross-sections were demonstrated using the electromagnetic scattering theory, leading to the first concrete expression of the TSF. The TSF establishes the relationship between the time-dependent absorption/scattering cross-sections at the stationery and growth phases of microalgal development. The concrete expression of the TSF provides a new way to calculate the time-dependent optical properties of microalgae using electromagnetic scattering theory. The areas where the TSF of microalgae has exciting potential are in remote sensing and photobioreactor applications.

physics.app-ph↗

arXiv2019

Ultra-broadband, few cycle pulses directly from a Mamyshev fiber oscillator

While the performance of mode-locked fiber lasers has been improved significantly, the limited gain bandwidth restricts them to generate ultrashort pulses approaching a few cycles or even shorter. Here we present a novel method to achieve few cycle pulses (~5 cycles) with ultra-broad spectrum (~400 nm). To our best knowledge, this is the shortest pulse width and broadest spectrum directly generated from fiber lasers. It is noteworthy that a dramatic ultrashort pulse evolution can be stabilized in a laser oscillator by the unique nonlinear processes of a self-similar evolution as a nonlinear attractor in the gain fiber and a perfect saturable absorber action of the Mamyshev oscillator.

physics.optics↗