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In this paper, an aerodynamic design method for a contra-rotating open rotor based on lifting line theory is presented. By changing the number of blades, the solidity and camber angle are changed, and several different aerodynamic designs are completed. The effect of solidity and camber angle on the aerodynamic performance is studied. The results show that when the number of blades increases, the solidity linearly increases while the camber angle nonlinearly decreases. There exists an optimal number of blades for aerodynamic design. The highest propulsion efficiency improved by 2.41% compared to the lowest value. The highest propulsion efficiency of 0.81 occurred with 10 blades. Increased solidity leads to increased viscous and wake losses. The change in solidity also changes the shock wave structure in the channel and the static pressure distribution on the blade surface. When the number of blades is reduced, decreased solidity results in greater circumferential differential pressure. The increased camber angle brings a larger inverse pressure gradient in the flow direction. This resulted in a significant flow reversal region in the channel, increasing the rear rotor root losses. [ABSTRACT FROM AUTHOR]

Featured Application: This work can be applied to enhancing traceability in complex supply chains, such as those in the food, pharmaceutical, or forestry industries, where transparency, security, and compliance with regulations are critical. The proposed solution can help businesses meet regulatory requirements, reduce fraud, ensure product authenticity, and increase consumer trust by providing tamper-proof records of every transaction and transformation along the supply chain. The growing importance of traceability in supply chains requires robust, transparent, and efficient systems to ensure the integrity and authenticity of product journeys. This paper presents a comprehensive characterisation and data model for a generic blockchain-based traceability system, highlighting its implementation using smart contracts on Ethereum-compatible networks, as the Ethereum Virtual Machine (EVM), with its pioneering implementation of smart contracts and its extensive ecosystem; it provides a robust environment for developing decentralised applications. We discuss the advantages of using blockchain technology to notarise traceability activities, ensuring immutability and transparency by exploring two main scenarios, namely one where hash keys (i.e, cryptographic digests) are stored on-chain while detailed data remain off-chain, and another where all traceability data are fully stored on-chain. Each approach is evaluated for its impact on scalability, privacy, storage efficiency, and operational costs. The hash key method offers significant advantages in reducing blockchain storage costs, enhancing privacy, and maintaining data integrity, but it depends on reliable off-chain storage. Conversely, the full on-chain approach guarantees data immutability but at a higher cost and lower scalability. By combining these strategies, a balanced solution can be achieved, leveraging the strengths of both methods to provide a reliable, efficient, and secure blockchain-based traceability system, which is illustrated with a practical implementation to support traceability in the timber sector in Galicia, Spain. This paper aims to provide valuable insights for researchers and practitioners looking to implement or enhance traceability systems using blockchain technology, demonstrating how smart contracts can be effectively utilised to meet the demanding requirements of modern supply chains. [ABSTRACT FROM AUTHOR]

In this paper, an aerodynamic design method for a contra-rotating open rotor based on lifting line theory is presented. By changing the number of blades, the solidity and camber angle are changed, and several different aerodynamic designs are completed. The effect of solidity and camber angle on the aerodynamic performance is studied. The results show that when the number of blades increases, the solidity linearly increases while the camber angle nonlinearly decreases. There exists an optimal number of blades for aerodynamic design. The highest propulsion efficiency improved by 2.41% compared to the lowest value. The highest propulsion efficiency of 0.81 occurred with 10 blades. Increased solidity leads to increased viscous and wake losses. The change in solidity also changes the shock wave structure in the channel and the static pressure distribution on the blade surface. When the number of blades is reduced, decreased solidity results in greater circumferential differential pressure. The increased camber angle brings a larger inverse pressure gradient in the flow direction. This resulted in a significant flow reversal region in the channel, increasing the rear rotor root losses.

The advent of blockchain technology has revolutionized various sectors by providing transparency, immutability, and automation. Central to this revolution are smart contracts, which facilitate trustless and automated transactions across diverse domains. However, the proliferation of smart contracts has exposed significant security vulnerabilities, necessitating advanced analysis techniques. Data dependency analysis is a critical program analysis method used to enhance the testing and security of smart contracts. This paper introduces Sligpt, an innovative methodology that integrates a large language model (LLM), specifically GPT-4o, with the static analysis tool Slither, to perform data dependency analyses on Solidity smart contracts. Our approach leverages both the advanced code comprehension capabilities of GPT-4o and the advantages of a traditional analysis tool. We empirically evaluate Sligpt using a curated dataset of Ethereum smart contracts. Sligpt achieves significant improvements in precision, recall, and overall analysis depth compared with Slither and GPT-4o, providing a robust solution for data dependency analysis. This paper also discusses the challenges encountered, such as the computational resource requirements and the inherent variability in LLM outputs, while proposing future research directions to further enhance the methodology. Sligpt represents a significant advancement in the field of static analysis on smart contracts, offering a practical framework for integrating LLMs with static analysis tools.

We propose a novel blockchain-based academic degree verification system. The system relies on a smart contract deployed on the Ethereum blockchain platform. The system protects the privacy of the students who have been verified without the need of encryption, and hence, avoid the complexity of security key management and the potential disaster if the keys are stolen or revealed. The amount of degree data is also designed to be minimum for proper verification. All operations on the critical path of the system are automated without any human intervention. However, the system does assume that the organization would stand behind the proposed system to ensure the system's integrity. The system is open to anyone who wishes to verify the degree of a student. To prevent spamming and to support the long-term sustainability of the system, a small fee is charged for each verification request. A portion of the fees collected is immediately credited to the participating schools. To facilitate automated school enrollment into the system, any school may request to enroll by placing a significant amount of stake in ETH. The stake can be refunded when the school decides to leave the system. However, if the school is blacklisted due to misbehavior, the stake is confiscated. This design strongly discourages adversaries from abusing the system. The performance of the system is fully characterized with regard to the gas consumption of key operations in various use cases. We demonstrate that the system is conducive for long-term sustainability. [ABSTRACT FROM AUTHOR]

One of the most significant barriers to blockchain adoption is the need for a better user experience. Tasks such as account setup, key management, and transaction handling need to be streamlined to propel the next wave of technological adoption across various sectors. A promising solution to these issues lies in account abstraction, which aims to simplify the user experience by masking the underlying complexities of blockchain technology. The most notable effort to implement account abstraction is Ethereum's ERC-4337, a proposal that addresses these pain points by enhancing flexibility and ease of use for developers and end users alike. This paper explores the account abstraction architecture, its functions and how it can redefine blockchain utility, from smart contracts to smart reporting. [ABSTRACT FROM AUTHOR]

The advent of blockchain technology has revolutionized various sectors by providing transparency, immutability, and automation. Central to this revolution are smart contracts, which facilitate trustless and automated transactions across diverse domains. However, the proliferation of smart contracts has exposed significant security vulnerabilities, necessitating advanced analysis techniques. Data dependency analysis is a critical program analysis method used to enhance the testing and security of smart contracts. This paper introduces Sligpt, an innovative methodology that integrates a large language model (LLM), specifically GPT-4o, with the static analysis tool Slither, to perform data dependency analyses on Solidity smart contracts. Our approach leverages both the advanced code comprehension capabilities of GPT-4o and the advantages of a traditional analysis tool. We empirically evaluate Sligpt using a curated dataset of Ethereum smart contracts. Sligpt achieves significant improvements in precision, recall, and overall analysis depth compared with Slither and GPT-4o, providing a robust solution for data dependency analysis. This paper also discusses the challenges encountered, such as the computational resource requirements and the inherent variability in LLM outputs, while proposing future research directions to further enhance the methodology. Sligpt represents a significant advancement in the field of static analysis on smart contracts, offering a practical framework for integrating LLMs with static analysis tools. [ABSTRACT FROM AUTHOR]

A composite smart contract can execute smart contracts that may belong to other owners or companies through external calls, bringing more security challenges to blockchain applications. Traditional static verification methods are inadequate for analyzing the dynamic execution of these contracts, resulting in misjudgment and omission issues. Therefore, this paper proposes a model checking approach based on dynamic behavior that verifies the security and business logic of composite smart contracts. Utilizing automata, the method models contracts, users, attackers, and extracts properties, focusing on six types of common security vulnerabilities. A thorough case study and experimental evaluation demonstrate the method's efficiency in identifying vulnerabilities and ensuring alignment with business requirements. The UPPAAL tool is employed for comprehensive verification, proving its effectiveness in enhancing smart contract security. [ABSTRACT FROM AUTHOR]

The facilitation of sharing and exchanging patients' health records is a paramount opportunity in e-health, enabling healthcare providers to garner a comprehensive and clear perspective of patients' medical histories without necessitating direct inquiries. Besides this great advantage, it introduces substantial issues on security and privacy, mainly related to unauthorized access to e-health records when different healthcare service providers maintain records. In this paper, we deal with this problem and propose using the blockchain technology (1) to obfuscate the linkage between patients' identities and their e-health records and (2) to grant access to e-health records exclusively to entities authorized by patients themselves. Key outcomes include using a digital identity based on the Electronic Identification, Authentication, and Trust Services Regulation (eIDAS) to control access to these records, and a concrete implementation by adopting the Ethereum blockchain. Our solution relies on using a public blockchain, which is an improvement for the state of the art, in which only private or consortium blockchains have been proposed. The resulting solution has been analyzed, and the effectiveness and affordability of the proposal have been shown. [ABSTRACT FROM AUTHOR]

Ethereum is the most widely used open-source public chain project, with smart contracts serving as the pattern for developing decentralized applications. The prevalence of attacks against smart contracts has increased in recent years due to the attached amounts of high-value cryptocurrency. Various attacks against smart contracts have caused significant financial losses, amounting to hundreds of millions of dollars. As manual auditing of smart contracts is time-consuming and costly, automatic detection of vulnerabilities is crucial. Existing work does not dig deeper into contextual information contained in the program, which suffers from the difficulty of covering paths with more complex conditions. In this paper, we propose Ethchecker, a smart contract vulnerability detection tool which combines fuzzing and symbolic execution techniques together. Particularly, we propose an analysis module to extract static information from smart contracts. Besides, the tool introduces a genetic algorithm to enlarge code coverage, while considering the contextual information of the code. The results of the experiment show that in terms of F1-score for vulnerability detection, Ethchecker outperforms sFuzz by an average of 21.89% and outperforms Mythril by an average of 12.5%. Furthermore, in the comparison experiments on a dataset consisting of 1000 long smart contract codes (comprising over 3000 instructions), the proposed algorithm can improve the code coverage by 18.56% compared to the random fuzzing algorithm. In addition, we also used Ethchecker to test against 8922 randomly crawled real-world smart contracts. The result demonstrates the stability of this tool. [ABSTRACT FROM AUTHOR]

This article explores ideas of solidity in the writings of Charlotte Brontë and Virginia Woolf. It is the first study of its kind in its aim to use solidity to reconcile two writers whose literary affinities, I propose, outnumber their differences. The article demonstrates that in Brontë's Villette (1853) and Woolf's The Waves (1931), the theme of solidity manifests itself in similar forms. It will show how the lingual, written or spoken word, which offers substantial sustenance to characters, is one such form. Similarly, it will show how solidity is present in both Brontë's and Woolf's portrayal of passion, the spiritual and the sexual. The presentation of solid objects as anchors and armours, tying characters to the real world, is a third similar manifestation of solidity in these works. Finally, a very remarkable common aspect of solidity can be found in their depiction of London, the urban setting that breeds knots of hardness. [ABSTRACT FROM AUTHOR]

In our previous work, we proposed a verification framework that shifts from the "code is law" to a new "specification is law" paradigm related to the safe evolution of smart contracts. The framework proposed there relaxed the well-established requirement that, once a smart contract is deployed in a blockchain, its code is expected to be immutable. More flexibly, contracts are allowed to be created and upgraded provided they meet a corresponding formal specification that was fixed. In the current paper, we extend this framework to allow specifications to evolve, provided a refinement notion is preserved. We propose a notion of specification refinement tailored for smart contracts and a methodology for checking it. In addition to weakening preconditions and strengthening postconditions and invariants, we allow for the change of data representation and interface extension. Thus, we are able to reason about a significantly wider class of smart contract evolution histories, when contrasted with the original framework. The new framework is centred around a trusted deployer: an off-chain service that formally verifies and enforces the notions of implementation conformance and specification refinement. We have investigated its applicability to the safe deployment and upgrade of contracts implementing widely used Ethereum standards (the ERC20 Token Standard, the ERC3156 Flash Loans, the ERC1155 Multi Token Standard and The ERC721 standard for Non-Fungible Tokens); we handle evolutions possibly involving changes in data representation and interface extensions. [ABSTRACT FROM AUTHOR]

Blockchain technology has captured the attention of various industries due to its potential to revolutionize traditional systems through decentralization, transparency and immutability. This paper examines the emerging trend of integrating blockchain-based decentralized applications (DApps) into the education sector. With blockchain's distributed ledger system, educational institutions can achieve safe, secure and transparent management of student achievements, certifications and credentials. The paper presents the architecture of a system that enables students to build verifiable digital portfolios of educational achievements stored and shared securely using smart contracts and digital tokens. By harnessing the benefits and addressing the challenges of blockchain DAppps in education, we can pave the way for a truly transformative era in the learning experience of tomorrow. [ABSTRACT FROM AUTHOR]

This paper investigates the potential of integrating supply chain management with blockchain technology, specifically by implementing smart contracts on the Ethereum network using Solidity. The paper explores supply chain management concepts, blockchain, distributed ledger technology, and smart contracts in the context of their integration into supply chains to increase traceability, transparency, and accountability with faster processing times. After investigating these technologies' applications and potential use cases, a framework for smart contract implementation for supply chain management is constructed. Potential data models and functions of a smart contract implementation improving supply chain management processes are discussed. After constructing a framework, the effects of the proposed system on supply chain processes are explained. The proposed framework increases the reliability of the supply chain history due to the usage of DLT (distributed ledger technology). It utilizes smart contracts to increase the manageability and traceability of the supply chain. The proposed framework also eliminates the SPoF (Single Point of Failure) vulnerabilities and external alteration of the transactional data. However, due to the ever-changing and variable nature of the supply chains, the proposed architecture might not be a one-size-fits-all solution, and tailor-made solutions might be necessary for different supply chain management implementations. [ABSTRACT FROM AUTHOR]

Smart contracts are self-executing programs stored and executed on a blockchain platform. However, previous studies demonstrated that developing secure smart contracts is not easy. Unfortunately, the use of insecure smart contracts results in a significant financial loss for service providers or customers. Therefore, identifying security vulnerabilities in smart contracts would be essential in blockchain platforms using smart contracts. In this paper, we present SmartConDetect as a tool for detecting security vulnerabilities in Solidity smart contracts. SmartConDetect is a static analysis tool that extracts code fragments from Solidity smart contracts and uses a pre-trained BERT model to find susceptible code patterns. To demonstrate the performance of SmartConDetect, we use two public datasets, and our dataset (SmartConDataset) collected from the real-world Ethereum blockchain network. Our experimental results show that SmartConDetect significantly outperforms all state-of-the-art methods, achieving 90.9% F1-score when using our own dataset. Specifically, SmartConDetect is about 2 times faster than SmartCheck in detection. Furthermore, we conduct a real-world case study to analyze the distribution of detected vulnerabilities. [ABSTRACT FROM AUTHOR]

The growing importance of traceability in supply chains requires robust, transparent, and efficient systems to ensure the integrity and authenticity of product journeys. This paper presents a comprehensive characterisation and data model for a generic blockchain-based traceability system, highlighting its implementation using smart contracts on Ethereum-compatible networks, as the Ethereum Virtual Machine (EVM), with its pioneering implementation of smart contracts and its extensive ecosystem; it provides a robust environment for developing decentralised applications. We discuss the advantages of using blockchain technology to notarise traceability activities, ensuring immutability and transparency by exploring two main scenarios, namely one where hash keys (i.e, cryptographic digests) are stored on-chain while detailed data remain off-chain, and another where all traceability data are fully stored on-chain. Each approach is evaluated for its impact on scalability, privacy, storage efficiency, and operational costs. The hash key method offers significant advantages in reducing blockchain storage costs, enhancing privacy, and maintaining data integrity, but it depends on reliable off-chain storage. Conversely, the full on-chain approach guarantees data immutability but at a higher cost and lower scalability. By combining these strategies, a balanced solution can be achieved, leveraging the strengths of both methods to provide a reliable, efficient, and secure blockchain-based traceability system, which is illustrated with a practical implementation to support traceability in the timber sector in Galicia, Spain. This paper aims to provide valuable insights for researchers and practitioners looking to implement or enhance traceability systems using blockchain technology, demonstrating how smart contracts can be effectively utilised to meet the demanding requirements of modern supply chains.

Leaves play an important role in species discrimination. An elliptic Fourier analysis (EFA) based morphometric technique was used to assess divergence between the poorly differentiated species, Callicarpa pedunculata and C. rubella. Using leaf specimen images from herbarium collections, principal components (PCs) were extracted from the Fourier coefficients and used to describe leaf outline and leaf shape descriptors: circularity, aspect ratio, and solidity. The results indicate that symmetric (54%) and asymmetric (35%) components of the leaves of C. pedunculata and C. rubella are sources of shape variation, as shown in the width and leaf tips among the samples. MANOVA revealed significant interspecific differences (P = 0.03) between C. pedunculata and C. rubella. The jack-knife cross-validation showed 71% of correctly classified species both in C. pedunculata and C. rubella. Furthermore, the results of this study were able to reveal significant leaf shape descriptors like aspect ratio, circularity, and solidity as important diagnostic characters in discriminating C. pedunculata and C. rubella. Thus, in conclusion, leaf serrations, leaf size, and leaf lobes are important characteristics in discriminating between C. pedunculata and C. rubella. [ABSTRACT FROM AUTHOR]

Nowadays, blockchain has become increasingly popular due to its promise of supporting critical business services in various areas. Blockchain systems, like Ethereum and Hyperledger Fabric, rely on sophisticated middleware, which enables the execution of smart contracts. Smart contracts define the business logic within cooperative applications. Detecting attacks and vulnerabilities within blockchain is a crucial issue for ensuring the security of different generations of blockchains. Testing a blockchain application serves multiple purposes: it ensures its quality, maximizes test coverage, and minimizes the risks associated with insufficient knowledge that could potentially impact the software development process. That is why several static analysis tools targeting Ethereum smart contracts and Hyperledger Fabric chaincode have recently been proposed by the blockchain research community. However, the efficiency of these analysis tools remains an open issue that requires further investigation. In this context, this paper presents a new taxonomy related to attacks targeting different generations of blockchain and evaluates the available analysis tools that can be utilized to assess the resilience of blockchain 2.0 and blockchain 3.0 against a range of vulnerabilities and attacks. Additionally, this study presents two quantitative analyses: one assessing the performance of tools in evaluating smart contract vulnerabilities within blockchain 2.0, and another analyzing the performance of tools in assessing blockchain 3.0 vulnerabilities within chaincode. Furthermore, this comprehensive study holds value for the research community as it considers various generations of blockchain. [ABSTRACT FROM AUTHOR]

Smart contracts are contracts between parties without an operating entity, and transactions can be implemented in code form through Solidity. However, once deployed, it is difficult to modify or delete, so attacks that exploit vulnerabilities in existing deployed contracts are increasing, and the scale of damage is significant. This paper proposes an automated vulnerability analysis framework that collects, detects, and analyzes contracts containing solidity-level vulnerabilities based on regular expression pattern matching. In the collection stage, contracts containing potential vulnerabilities are stored in a database through regular expression matching patterned against tokens and open sources that occur in the latest Ethereum network. In the analysis stage, the false positives and analysis performance of contracts collected with existing smart contract vulnerability analysis tools are compared and analyzed. Through the proposed framework, we expect to be able to evaluate zero-day vulnerability trends and the effectiveness of analysis tools in the smart contract ecosystem. [ABSTRACT FROM AUTHOR]

The current healthcare insurance claim requires more procedures to be claimed from an insurance company. Healthcare insurance companies are crucial for patient financial assistance, but efficient claim processing can lead to lower the levels of care. Patients have already claimed insurance in certain locations and are attempting to claim it again in another location. This work proposes to increase claim speed, avoid fraudulent claims, and provide privacy for patient data on decentralized storage through permissioned blockchain. To ensure patient data privacy and assist insurance agents and individuals in verifying eligibility and claim status, hash values are used to store data in a block. Every claim's information is stored in a block. If the patient attempts to claim again, the agent will validate the block and have the option to accept or reject the request. The integrity, speed, and security of patient health information can be achieved through this technique. [ABSTRACT FROM AUTHOR]

With the ever-increasing advancement in blockchain technology, security is a significant concern when substantial investments are involved. This paper explores known smart contract exploits used in previous and current years. The purpose of this research is to provide a point of reference for users interacting with blockchain technology or smart contract developers. The primary research gathered in this paper analyses unique smart contracts deployed on a blockchain by investigating the Solidity code involved and the transactions on the ledger linked to these contracts. A disparity was found in the techniques used in 2021 compared to 2023 after Ethereum moved from a Proof-of-Work blockchain to a Proof-of-Stake one, demonstrating that with the advancement in blockchain technology, there is also a corresponding advancement in the level of effort bad actors exert to steal funds from users. The research concludes that as users become more wary of malicious smart contracts, bad actors continue to develop more sophisticated techniques to defraud users. It is recommended that even though this paper outlines many of the currently used techniques by bad actors, users who continue to interact with smart contracts should consistently stay up to date with emerging exploitations. [ABSTRACT FROM AUTHOR]

I analyze an argument by Aquinas on God’s will mutability (Summa Theologica), which presupposes the collective predication on the term ‘man’. This explains why God repents of having made the collection of men, but not some men. The argument is valid, but its second premise and its conclusion are false.

Solidity is an important parameter in the design, manufacture, and operation concerning energy yield and performance efficiency of VAWTs. This paper examined detailed aerodynamic analysis of solidity effects at constant Re and at low Reynolds numbers, the flow field and forces (lift, drag, and Torque coefficients) aerodynamics at various azimuth positions, and the changes in the performance and the flow field of VAWTs at a wide range of TSR. The simulation of two three-bladed VAWT configurations, σ = 0.26 (C = 0.03 m) and σ = 0.34 C = 0.04 m) over 1.5 ≤ λ ≤ 5.5 tip speed ratios on the CL, CD, CM, and speed were monitored and extracted, and the blades surrounding flow field is plotted from the CFD simulations. Performance (Cp -λ) curves, force hysteresis, and plots of the flow field for the turbines are matched at low λ = 2 5, high λ = 4, and Reynolds number to explain solidity effects on the VAWTs performance and aerodynamics thus providing good insight into the underlying aerodynamics for the differences in power coefficient between the two rotors in detail. This allowed the linking of the performance to the detailed force and flow field aerodynamics at various azimuth angles. It has been shown that the initiation of blade stall and stall vortices shedding started earlier on the σ = 0.26 VAWT than the σ =0.34 VAWT, thus affecting the force attained and ultimately limiting the rotor efficiency of σ = 0.26 compared with the σ =0.34 rotor and provided an improved understanding of solidity phenomenon that will help in the design, production and operation of VAWTs.

This paper presents MindTheDApp, a toolchain designed specifically for the structural analysis of Ethereum-based Decentralized Applications (DApps), with a distinct focus on a complex network-driven approach. Unlike existing tools, our toolchain combines the power of ANTLR4 and Abstract Syntax Tree (AST) traversal techniques to transform the architecture and interactions within smart contracts into a specialized bipartite graph. This enables advanced network analytics to highlight operational efficiencies within the DApp’s architecture. The bipartite graph generated by the proposed tool comprises two sets of nodes: one representing smart contracts, interfaces, and libraries, and the other including functions, events, and modifiers. Edges in the graph connect functions to smart contracts they interact with, offering a granular view of interdependencies and execution flow within the DApp. This network-centric approach allows researchers and practitioners to apply complex network theory in understanding the robustness, adaptability, and intricacies of decentralized systems. Our work contributes to the enhancement of security in smart contracts by allowing the visualisation of the network, and it provides a deep understanding of the architecture and operational logic within DApps. Given the growing importance of smart contracts in the blockchain ecosystem and the emerging application of complex network theory in technology, our toolchain offers a timely contribution to both academic research and practical applications in the field of blockchain technology.