arXiv subjects

Liang Ji

Publications and source records attributed to Liang Ji.

5 recordsLinked to original sources

arXiv2026

Token Communications (TokCom): A Unified AI-Native Communication Framework

As artificial intelligence (AI) evolves from static perception to generative reasoning and autonomous agency, the fundamental principles of wireless communications are undergoing a paradigm shift. The classical Shannon paradigm, centered on reliable bit-level reconstruction for users, is increasingly misaligned with an emerging scenario in which the primary users of the network are interconnected AI agents. This article introduces token communications (TokCom), a novel framework that elevates tokens, i.e., the fundamental processing units of large language models (LLMs), to first-class entities for information exchange in the sixth generation wireless cellular networks (6G). We first examine the architectural transition from conventional communication systems to TokCom and identify the key challenges in implementing this transition, along with potential solution approaches. Thereafter, we present a practical case study to demonstrate the effectiveness of token sharing among heterogeneous language models. Finally, we outline promising future research directions toward realizing an AI-native, token-driven communication paradigm suitable for 6G.

cs.NI↗

arXiv2026

KinDER: A Physical Reasoning Benchmark for Robot Learning and Planning

Robotic systems that interact with the physical world must reason about kinematic and dynamic constraints imposed by their own embodiment, their environment, and the task at hand. We introduce KinDER, a benchmark for Kinematic and Dynamic Embodied Reasoning that targets physical reasoning challenges arising in robot learning and planning. KinDER comprises 25 procedurally generated environments, a Gymnasium-compatible Python library with parameterized skills and demonstrations, and a standardized evaluation suite with 13 implemented baselines spanning task and motion planning, imitation learning, reinforcement learning, and foundation-model-based approaches. The environments are designed to isolate five core physical reasoning challenges: basic spatial relations, nonprehensile multi-object manipulation, tool use, combinatorial geometric constraints, and dynamic constraints, disentangled from perception, language understanding, and application-specific complexity. Empirical evaluation shows that existing methods struggle to solve many of the environments, indicating substantial gaps in current approaches to physical reasoning. We additionally include real-to-sim-to-real experiments on a mobile manipulator to assess the correspondence between simulation and real-world physical interaction. KinDER is fully open-sourced and intended to enable systematic comparison across diverse paradigms for advancing physical reasoning in robotics. Website and code: https://prpl-group.com/kinder-site/

cs.RO↗

arXiv2024

Experimental and Computational Investigation of the Influence of Ethanol on Auto-ignition of n-Heptane in Non-Premixed Flows

Experimental and computational investigations are carried out to elucidate the influence of ethanol addition on n-heptane auto-ignition in counterflows. An axisymmetric stream of air, temperature gradually increased, is directed onto the surface of an evaporating pool of a liquid fuel. The air-stream temperature at auto-ignition is measured at various strain rates for n-heptane, ethanol, and various n-heptane/ethanol mixtures. Critical conditions for auto-ignition are predicted employing San Diego Mechanism for both fuels and fuel mixtures, and the results are compared with measurements. Measurements and predictions show that low-temperature chemistry (LTC) plays a significant role in promoting auto-ignition of n-heptane at low strain rates, but there is insufficient residence time at high strain rates for LTC to take place, so auto-ignition is promoted by high-temperature chemistry. Experimental and computational results show addition of ethanol inhibits LTC of n-heptane. To identify the responsible elementary steps, computations are performed to identify those dominate O2 consumption and contribute to the temperature rise in the reaction zone for n-heptane and n-heptane/ethanol mixtures at low strain rates. For n-heptane, O2 is consumed primarily by the low-temperature steps that result in ketohydroperoxide; the temperature rise is produced by subsequent LTC steps. For the mixtures, a key step consuming O2 is O2 + CH3CHOH = HO2 + CH3CHO, and the heat release occurs through the classical high-temperature reaction mechanism. Thus, the inhibition of auto-ignition that is observed to occur when ethanol is added to n-heptane arises from the competition for O2 between this step and the LTC addition of O2 to the heptyl radical and to the radical arising from the subsequent isomerization, for n-heptane.

physics.chem-ph↗

arXiv2024

Analysis of Flame Structure and Interactions Between Chemical Reactions, Species Transport and Heat Release in Laminar Flames

A novel method for analyzing counterflow diffusion flames, inspired by Zurada's sensitivity approach for neural networks, is proposed to identify critical species influencing the heat release rate in combustion. By further analyzing concentration changes of selected key species and radicals, this method reveals complex interactions among them across regions with temperature. To illustrate this approach, the study investigates the mechanisms of auto-ignition of n-heptane and ethanol mixtures in a counterflow configuration under low strain rates. In mixtures where n-heptane is dominant, the inhibition of low-temperature chemistry (LTC) by addition of ethanol impacts the heat release rate in regions where the temperature is higher through the diffusion of specific radicals such as CH2O, C2H4, C3H6, and H2O2. In mixtures where ethanol is dominant, the high ethanol fractions in the mixture increase the heat release rate, primarily due to ethanol decomposition and its subsequent reactions. This method effectively quantifies and compares the influence of both chemical kinetics and species diffusion effects, providing detailed insights into the interactions among species across the reactive field when analyzing the counterflow configuration of complex fuel mixtures.

physics.chem-ph↗

arXiv2020

280-km experimental demonstration of quantum digital signature with one decoy state

Quantum digital signature (QDS) guarantee the unforgeability, nonrepudiation and transferability of signature messages with information-theoretical security, and hence has attracted much attention recently. However, most previous implementations of QDS showed relatively low signature rates or/and short transmission distance. In this paper, we report a proof-of-principle phase-encoding QDS demonstration using only one decoy state. Firstly, such method avoids the modulation of vacuum state, thus reducing experimental complexity and random number consumption. Moreover, incorporating with low-loss asymmetric Mach-Zehnder interferometers and real-time polarization calibration technique, we have successfully achieved higher signature rate, e.g., 0.98 bit/s at 103 km, and to date a record-breaking transmission distance over 280-km installed fibers. Our work represents a significant step towards real-world applications of QDS.

quant-ph↗