The quest for carbon neutrality in the 21st century has led to the rise of decentralized low-carbon energy systems as a promising solution. Blockchain technology has played a pivotal role in catalyzing this transition, with various Web3 projects exploring decentralized operational models and carbon credit markets. However, there is a notable gap in harnessing blockchain’s potential to integrate electric vehicles (EVs) into low-carbon energy systems effectively. This article addresses this gap by proposing a decentralized low-carbon EV charging system that enables transactions between individual low-carbon energy producers and EV owners. Leveraging blockchain and smart contracts, the proposed system issues low-carbon tokens to certify and incentivize environmentally conscious charging behaviors, while enabling token circulation to further promote low-carbon participation. A blockchain-based double auction mechanism is designed to ensure fair and efficient energy allocation, achieving individual rationality, incentive compatibility, and social welfare maximization. By incentivizing user engagement and ensuring fair transactions, this model paves the way for sustainable EV integration within low-carbon energy systems.

International audience

Mesh simplification of 3D models can accelerate rendering, reduce storage space, and improve performance. However, for high-poly 3D models, there are ongoing concerns about potentially compromising the Quality of Experience (QoE), the need to set simplification ratios or parameters, and the time-consuming nature of the simplification process. To address these issues, we proposed a new mesh simplification for the preprocessing step. Based on the Quadratic Error Metric (QEM) simplification algorithm, we conducted human-centered 3D model comparison experiments to determine the optimal simplification ratio for high-poly 3D models in full body shots. From experimental data, we proposed and implemented ASimp, an automatic 3D mesh simplification scheme. In evaluation experiments, ASimp demonstrated rapid preprocessing speeds while ensuring QoE and the effectiveness of its simplification products. We hope that ASimp will contribute to the optimization of 3D models and find applications in fields such as cultural heritage, archaeology, visual effects, video games, medicine, metaverse, and beyond.

Current 3D model Level of Detail (LOD) methods require multiple models with varying detail levels to reduce client computational load, transmitting different models based on the user's distance to the object. However, this process consumes excessive network bandwidth and strains the client's memory and storage. To address this, we propose BS3 (Bézier Slicing for 3Ds), a middleware-enabled method that slices 3D meshes and fits the contours using Bézier curves. Acting as an intermediate layer, the BS3 middleware handles slicing, vectorization, sampling and reconstruction, allowing .bs3 files to be streamed only once and adjusted dynamically at different sampling rates. Our experiments demonstrate the efficiency and performance analysis of BS3, which shows that it can reduce network and storage burdens while keeping the display effect. We believe that BS3 will enhance 3D multimedia in the game, exhibition, digital museum, cultural heritage, metaverse, etc.

In the Web3 ecosystem, multimedia applications exhibit significant potential by leveraging decentralization, regarded as the core spirit of Web3. This survey aims to provide a comprehensive overview of the potential of decentralization in shaping multimedia applications in the Web3 ecosystem. Through a systematic review of the academic research conducted over the past decade on Web3 decentralization, we identify the two key distinctive decentralization characteristics (decentralized assets and decentralized participation). Subsequently, we comprehensively analyze Web3 applications from both technology and application dimensions. Building upon this, we focus on multimedia-related aspects and propose an architecture for Web3 multimedia applications. In contrast to the broader scope of Web3 applications, the unique aspects of Web3 multimedia applications reside in their core application components (non-fungible tokens and smart contract-based rules) and core application domains (art, games, and social media). Based on this architecture, we provide a precise definition of Web3 multimedia applications. Lastly, through the lens of the two identified distinctive decentralization characteristics, we investigate the advantages, development, and limitations of Web3 multimedia applications within the three core application domains, namely crypto art, blockchain games, and blockchain on social media (BOSM). Furthermore, we share our insights into several promising yet challenging directions, covering the interoperability and potential of increasingly valuable multimedia content, as well as the delicate balance between centralization and decentralization.

Non-Fungible Tokens (NFTs) have emerged as a pivotal digital asset, offering authenticated ownership of unique digital content. Despite it has gained remarkable traction, yet face pressing storage and verification challenges stemming from blockchain's permanent data costs. Existing off-chain or centralized storage solutions, while being alternatives, also introduce notable security vulnerabilities. We present SemNFT, an innovative decentralized framework integrated with blockchain oracle middleware services, addressing these persistent NFT dilemmas. Our approach compresses NFT source data into compact embeddings encapsulating semantic essence. These arrays are stored on-chain, while facilitating reliable decentralized image reconstruction and ownership verification. We implemented ERC721-compliant smart contracts with supplementary functionalities, demonstrating SemNFT's seamless integrative capabilities within the ecosystem. Extensive evaluations evidence marked storage optimizations and preservation of requisite visual fidelity by comparison with existing solutions. The proposed SemNFT framework marks a significant advancement in holistically confronting rising NFT storage and verification challenges without compromising decentralization. It substantively propels the meaningful evolution of NFT infrastructure to achieve digital asset immortality.

As mobile applications grow increasingly computation-intensive, the challenges arising from the limitations of mobile devices in terms of computing resources and battery life become more pronounced. Mobile Edge Computing (MEC) provides a promising avenue to address these challenges and enhance user experience. While existing studies have extensively explored resource allocation and task scheduling in MEC, most treat tasks as monolithic entities, overlooking the nuanced subtasks/components that often make up mobile applications. This paper endeavors to bridge the gap between the need for incentive mechanisms and the offloading of dependent computation tasks in MEC. Drawing inspiration from auction theory, we introduce a novel Multi-stage Iterative Combinatorial Double Auction (MICDA) mechanism, specifically tailored for dependent tasks in a cloud-edge-end cooperative computing scenario. Through theoretical analysis, the MICDA mechanisms demonstrate truthfulness, individual rationality, budget balance, and computational efficiency. Comprehensive experiment results further confirm its superior performance in improving application makespan and social welfare compared to other existing offloading strategies. This work validates the effective integration of dependency-aware computation offloading and auction mechanisms in overcoming economic and computational challenges in MEC systems, thereby paving the way for their potential application in broader real-world scenarios.

Widely adopted digital cameras and smartphones have generated a large number of videos, which have brought a tremendous workload to video editors. Recently, a variety of automatic/semi-automatic video editing methods have been proposed to tackle these issues in some specific areas. However, for the production of meeting recordings, the existing studies highly depend on extra equipment in the conference venues, such as the infrared camera or special microphone, which are not practical. In this article, we design and implement Meetor, a human-centered automatic video editing system for meeting recordings. The Meetor mainly contains three parts: an audio-based video synchronization algorithm, human-centered video content flaw detection algorithms, and an automatic video editing algorithm. Two main experiments are conducted from both objective and subjective aspects to evaluate the performance of the Meetor. The experimental results on a testbed illustrate that the proposed algorithms could achieve state-of-the-art (SOTA) performance in video content flaw detection. However, the conducted user study demonstrates that Meetor could generate meeting recordings with a satisfactory quality compared with professional video editors. Moreover, we also present a practical application of the Meetor in a university campus prototype, in which the Meetor is applied in the automatic editing of lecture recordings. All in all, the proposed Meetor can be utilized in practical applications to release the workload of professional video editors.

Recently, the concept of metaverse has been rapidly emerging, which highly expands the human living space. Specifically, 3D models are at the heart of building a vast metaverse space, so a massive number of 3D models are needed. Existing 3D model libraries and platforms have achieved great results. However, most of them are unscalable, insufficiently open, inefficient to collect, and at risk of service disruption and data corruption. Therefore, we propose and implement Web3DP, a crowdsourcing platform for 3D models based on Web3 (a.k.a. Web 3.0) infrastructure. By using the decentralized blockchain technology, Web3DP has the advantages of transparency, auditability, traceability, data tamper-proof, high file transfer efficiency, and service stability. Experiments are conducted to validate the performance of the proposed platform. It illustrates that Web3DP shows better file transmission capabilities with an acceptable transaction fee to facilitate 3D model collecting and managing for metaverse, games, cultural heritage, etc.

Widely adopted digital cameras and smartphones have generated a large number of videos, which have brought a tremendous workload to video editors. Recently, a variety of automatic/semi-automatic video editing methods have been proposed to tackle this issue in some specific areas. However, for the production of meeting recordings, the existing studies highly depend on additional conditions of conference venues, like infrared camera or special microphone, which are not practical. Moreover, current video quality assessment works mainly focus on the quality loss after compression or encoding rather than the human-centered video content flaws. In this paper, we design and implement FLAD, a human-centered video content flaw detection system for meeting recordings, which could build a bridge between subjective sense and objective measures from a human-centered perspective. The experimental results illustrate the proposed algorithms could achieve the state-of-the-art video content flaw detection performance for meeting recordings.

Text analysis tools are often utilized to store and analyze massive texts in modern oral history research. However, the state-of-the-art centralized text analysis systems are suffering from data synchronization, maintenance, and cross-platform compatibility issues in a stand-alone environment, while the server-based ones are struggling from the lack of commitment to long-term support and unforeseen security risks, e.g. data leakage and loss. In this work, Seshat, a decentralized oral history text analysis system, employs Inter-Planetary File System (IPFS) storage, blockchain, and web technologies to address these issues. With Seshat, the text processing operations are localized in users’ terminals, while the data and analytical logics are permanently preserved on the blockchain. Experiments are conducted to validate the performance of the proposed system. By sacrificing affordable text processing time, Seshat shows better robustness and compatibility to facilitate effective digital assistance for text analysis applications like oral history studies.