Enabling Decentralized and Dynamic Data Integrity Verification for Secure Cloud Storage via T-Merkle Hash Tree Based Blockchain

Cloud storage provides elastic storage services for enterprises and individuals remotely. However, security problems such as data integrity are becoming a major obstacle. Recently, blockchain-based verification approaches have been extensively studied to get rid of a centralized third-party auditor. Most of these schemes suffer from poor scalability and low search efficiency and even fail to support data dynamic update operations on blockchain, which limits their large-scale and practical applications. In this work, we propose a blockchain-based dynamic data integrity verification scheme for cloud storage with T-Merkle hash tree. A decentralized scheme is proposed to eliminate the restrictions of previous centralized schemes. The data tags are generated by the technique of ZSS short signature and stored on blockchain. An improved verification method is designed to check the integrity of cloud data by transferring computation from a verifier to cloud server and blockchain. Furthermore, a storage structure called T-Merkle hash tree which is built based on T-tree and Merkle hash tree is designed to improve storage utilization of blockchain and support binary search on chain. Moreover, we achieve efficient and secure dynamic update operations on blockchain by an append-only manner. Besides, we extend our scheme to support batch verification to handle massive tasks simultaneously; thus, the efficiency is improved and communication cost is reduced. Finally, we implemented a prototype system based on Hyperledger Fabric to validate our scheme. Security analysis and performance studies show that the proposed scheme is secure and efficient.

Dynamic Update Method of Working Face Geological Model Driven by Multi-Source Data

In order to build a high-precision dynamic geological model to serve the intelligent mining, working face is explored step by step through the comprehensive prospecting technology. A multi-source data fusion method was applied to realize mutual verification, supplement, fusion and interpretation of non-uniform heterogeneous geological data to obtain a high-precision geological data volume. Also, the dynamic update model method was proposed to update 3D geological model of working face quickly so that the accuracy of the geological model can be improved effectively. Furthermore, cutting path planning technology was developed based on the dynamic geological model. The field test showed that the cutting path planning based on the high-precision dynamic geological model can improve the coal mining efficiency and improve the fusion efficiency between geology and coal mining systems. Dynamic update of multi-attribute geological information should be studied and developed to improve the automatic level of mining driven by geological data.

The Challenge: Non-propositionalism

Recent literature has presented a serious challenge for propositional accounts of content. It has been argued that certain bits of natural language discourse, in particular, modal claims, pose a fundamental challenge for propositional accounts, as they fail to express propositional content even relative to a context. The puzzling linguistic behavior of modal discourse suggests that context simply cannot determine propositional content for such claims. This appears to call for a re-thinking of the interaction between context and content, and their role in communication. Indeed, various non-propositionalist accounts that have been proposed to capture this puzzling behavior call for such re-thinking. Such accounts have received various implementations, for instance, in various expressivist and dynamic update semantics. These accounts deny that modals express ordinary propositional content, and they also deliver a non-classical logic. This chapter introduces the challenge, and the main features of non-propositional accounts that have been proposed as a solution.

A study on the hydrodynamic performance of manta ray biomimetic glider under unconstrained six-DOF motion

A manta ray biomimetic glider is designed and studied with both laboratory experiments and numerical simulations with a new dynamic update method called the motion-based zonal mesh update method (MBZMU method) to reveal its hydrodynamic performance. Regarding the experimental study, an ejection gliding experiment is conducted for qualitative verification, and a hydrostatic free-fall experiment is conducted to quantitatively verify the reliability of the corresponding numerical simulation. Regarding the numerical simulation, to reduce the trend of nose-up movement and to obtain a long lasting and stable gliding motion, a series of cases with the center of mass offset forward by different distances and different initial angles of attack have been calculated. The results show that the glider will show the optimal gliding performance when the center of mass is 20mm in front of the center of geometry and the initial attack angle range lies between A0 = -5° to A0 = -2.5° at the same time. The optimal gliding distance can reach six times its body length under these circumstances. Furthermore, the stability of the glider is explained from the perspective of Blended-Wing-Body (BWB) configuration.