arXiv subjects

Siqiao Li

Publications and source records attributed to Siqiao Li.

6 recordsLinked to original sources

arXiv2026

Dominance-Based Feasibility Inference for Packing-Constrained Pickup and Delivery Problems

Routing and packing are intrinsically coupled in transport problems, requiring joint planning for cost-efficient and physically realizable solutions. We study a pickup and delivery problem with two-dimensional packing constraints (2P-PDP). Unlike vehicle routing variants where items are loaded before vehicles leave the depot and packing is validated only once, the 2P-PDP induces non-monotonic free-space evolution, substantially increasing feasibility-checking complexity. To address this bottleneck, we propose a generic dominance-based feasibility framework that is embeddable in a broad class of exact and heuristic routing algorithms. Under no-relocation constraints, inferring feasibility from a previously verified packing state requires preserving the pickup and delivery order of onboard items. To this end, we introduce an order-preserving mapping that jointly captures geometric containment and sequence compatibility, enabling dominance-based inference by embedding the new packing state into a verified reference plan. To further reduce dominance-screening overhead, we design three search rules to guide candidate exploration and tailored strategies to store, retrieve, and prioritize verified states. Computational experiments show that the proposed approach reduces feasibility-checking time by up to 42% compared to a benchmark without dominance. The improvement stems from reducing exact packing-procedure calls, shifting verification effort away from the most computationally expensive stage.

math.OC↗

arXiv2025

LVPNet: A Latent-variable-based Prediction-driven End-to-end Framework for Lossless Compression of Medical Images

Autoregressive Initial Bits is a framework that integrates sub-image autoregression and latent variable modeling, demonstrating its advantages in lossless medical image compression. However, in existing methods, the image segmentation process leads to an even distribution of latent variable information across each sub-image, which in turn causes posterior collapse and inefficient utilization of latent variables. To deal with these issues, we propose a prediction-based end-to-end lossless medical image compression method named LVPNet, leveraging global latent variables to predict pixel values and encoding predicted probabilities for lossless compression. Specifically, we introduce the Global Multi-scale Sensing Module (GMSM), which extracts compact and informative latent representations from the entire image, effectively capturing spatial dependencies within the latent space. Furthermore, to mitigate the information loss introduced during quantization, we propose the Quantization Compensation Module (QCM), which learns the distribution of quantization errors and refines the quantized features to compensate for quantization loss. Extensive experiments on challenging benchmarks demonstrate that our method achieves superior compression efficiency compared to state-of-the-art lossless image compression approaches, while maintaining competitive inference speed. The code is at https://github.com/scy-Jackel/LVPNet.

eess.IV↗

arXiv2025

MS-IQA: A Multi-Scale Feature Fusion Network for PET/CT Image Quality Assessment

Positron Emission Tomography / Computed Tomography (PET/CT) plays a critical role in medical imaging, combining functional and anatomical information to aid in accurate diagnosis. However, image quality degradation due to noise, compression and other factors could potentially lead to diagnostic uncertainty and increase the risk of misdiagnosis. When evaluating the quality of a PET/CT image, both low-level features like distortions and high-level features like organ anatomical structures affect the diagnostic value of the image. However, existing medical image quality assessment (IQA) methods are unable to account for both feature types simultaneously. In this work, we propose MS-IQA, a novel multi-scale feature fusion network for PET/CT IQA, which utilizes multi-scale features from various intermediate layers of ResNet and Swin Transformer, enhancing its ability of perceiving both local and global information. In addition, a multi-scale feature fusion module is also introduced to effectively combine high-level and low-level information through a dynamically weighted channel attention mechanism. Finally, to fill the blank of PET/CT IQA dataset, we construct PET-CT-IQA-DS, a dataset containing 2,700 varying-quality PET/CT images with quality scores assigned by radiologists. Experiments on our dataset and the publicly available LDCTIQAC2023 dataset demonstrate that our proposed model has achieved superior performance against existing state-of-the-art methods in various IQA metrics. This work provides an accurate and efficient IQA method for PET/CT. Our code and dataset are available at https://github.com/MS-IQA/MS-IQA/.

eess.IV↗

arXiv2024

Call center data analysis and model validation

We analyze call center data on properties such as agent heterogeneity, customer patience and breaks. Then we compare simulation models that are different in the ways these properties are modeled. We classify them according to the extend in which they approach the actual service level and average waiting times. We obtain a theoretical understanding on how to distinguish between the model error and other aspects such as random noise. We conclude that modeling explicitly breaks and agent heterogeneity is crucial for obtaining a precise model.

stat.AP↗

arXiv2021

S-band single-longitudinal-mode erbium-doped fiber ring laser with ultra-narrow linewidth, ultra-high OSNR, high stability and low RIN

A high-performance S-band single-longitudinal-mode (SLM) erbium-doped fiber (EDF) ring cavity laser based on a depressed cladding EDF is investigated and experimentally demonstrated. We combine a double-ring passive resonator (DR-PR) and a length of unpumped polarization maintaining (PM) EDF in the laser cavity to achieve the SLM lasing without mode hopping. The DR-PR, composed of two efficient dual-coupler fiber rings, is utilized to expand the free spectral range of the EDF ring cavity laser and to eliminate the dense longitudinal modes greatly. The PM EDF, insusceptible to random change induced by environmental perturbations, is used as a saturable absorber filter to guarantee and to stabilize the SLM operation of the EDF ring cavity laser. At the pump power of 400 mW, we obtain an SLM EDF ring laser with a linewidth as narrow as 568 Hz, an optical signal-to-noise ratio as high as 77 dB, and a relative intensity noise as low as 140 dB/Hz at the frequency over 5 MHz. Meanwhile, the stability performance of both the wavelength lasing and the output power, the dependence of the OSNR and the output power on pump power for the S-band fiber laser are also investigated in detail.

physics.optics↗

arXiv2021

All-Polarization Maintaining Single-Longitudinal-Mode Fiber Laser with Ultra-High OSNR, Sub-kHz Linewidth and Extremely High Stability

An all-polarization maintaining (PM) single-longitudinal-mode (SLM) erbium-doped fiber laser (EDFL) with ultra-high optical signal-to-noise ratio (OSNR), ultra-narrow linewidth and extremely high stability is proposed and experimentally demonstrated. A double-ring passive subring resonator (DR-PSR) composed of two single-coupler fiber rings and a length of unpumped EDF-based saturable absorber filter is designed and employed in the EDFL to serve as the efficient SLM selecting element to guarantee SLM lasing with excellent output performance. The all-PM structure enables the proposed EDFL to present strong ability to resist the environment disturbance. At the pump power of 100 mW, we obtain an SLM EDFL with an ultra-high OSNR of 83 dB and an ultra-narrow linewidth of 459 Hz. For the SLM operation, the all-PM EDFL processes outstanding stability performance of both the wavelength lasing and the output power. The maximum fluctuations of the center wavelength and output power are 0.012 nm and 0.01 dB.

physics.optics↗