Search

The blockchain runs in a complex topological network which is affected by the principle of consensus, and data storage between nodes needs to maintain global consistency in the entire network, which causes the data storage inefficient. At the same time, the information exchange between large-scale communication node groups leads to the problems of bandwidth expropriation and excessive network load. In response to these problems, this article proposes a second-degree branch structure blockchain expansion model. First, a ternary storage structure is established. Data use the way of fully integrated storage, multi-cell storage, and fully split storage, and data are classified and stored in parallel between the structures. Second, a second-degree branch chain model is constructed. The main chain forks into multiple sub-chains, and a free competition chain structure and a Z-type chain structure are defined; a two-way rotation mechanism is introduced to realize the integration and transition between chain structures. Finally, a set of malicious attacks is simulated to realize the security constraints of the blockchain, to verify the security of the second-degree branch chain model. Experiment shows that the second-degree branch structure expansion model proposed in this article has great advantages in data storage efficiency and network load. [ABSTRACT FROM AUTHOR]

In order to foster a modern economic system and facilitate high-quality economic development, it is crucial to establish a conducive business environment. Undoubtedly, the evaluation of the business environment for enterprises constitutes a prominent area of research. Nevertheless, ensuring the authenticity and security of the raw data sources provided by participating enterprises poses a challenge, thereby compromising the accuracy of the evaluation. To tackle this issue, an enterprise composite blockchain construction method for business environment is proposed in this paper, which stores the raw data of enterprises by the means of hybrid on-chain and off-chain. Initially, the enhanced hash function SHA256 is introduced to encrypt the raw data of enterprises. The encrypted data is subsequently stored in an off-chain Level DB database, which is based on non-volatile memory. This approach effectively alleviates the burden on communication and storage. Secondly, a composite storage strategy on-chain is adopted: the key values from the Level DB are stored in the DAG-based Conflux public blockchain, while the enterprise state data is stored in the consortium blockchain, so as to provide trusted evidence of business environment evaluation data. Finally, it is demonstrated through a large number of experimental comparisons that the enterprise composite blockchain construction method proposed in this paper exhibits better read and write performance, lower storage efficiency and storage overhead, and outperforms both the before-improved Level DB database and existing blockchain storage models. [ABSTRACT FROM AUTHOR]

In recent years, blockchain security issues have attracted widespread attention. Especially in terms of computing power security, when nodes have sufficient computing power, they can arbitrarily tamper with blockchain ledger data. As a huge collection of computing power, the blockchain mining pool is a potential malicious node. Multiple malicious nodes jointly conduct a double-spending attack on the blockchain, which brings great security risks to the blockchain. This paper studies the different combinations of double-spending attack by potential malicious mining pools, constructs a blacklist judgment strategy based on the attack characteristics, and proposes a blockchain-based multi-malicious double-spending attack blacklist management model. Firstly, an inner loop malicious game is proposed to analyze the competition trend between a single malicious node and other malicious nodes. Secondly, according to the attack mode of multiple mining pools, a joint attack model and a decentralized attack model are proposed, and the operation rules of the two attack models are mathematically derived. Then a blacklist management model is proposed, and after the blacklist is constructed, a blacklist judgment strategy is formulated. The blacklist uses decentralize mining pool judgments and joint mining pool judgments to extract malicious mining pool nodes, which stops further malicious behavior. And finally, simulation experiments show that the blacklist management model can significantly reduce the success of attacks and resist double-spending attacks effectively. [ABSTRACT FROM AUTHOR]

Blockchain-based applications are becoming more and more widespread in business operations. In view of the shortcomings of existing enterprise blockchain evaluation methods, this paper proposes a multi-source heterogeneous blockchain data quality evaluation model for enterprise business activities, so as to achieve efficient evaluation of business activity information consistency, credibility and value. This paper proposes a multi-source heterogeneous blockchain data quality assessment method for enterprise business activities, aiming at the problems that most of the data in enterprise business activities come from different data sources, information representation is inconsistent, information ambiguity between the same block chain is serious, and it is difficult to evaluate the consistency, credibility and value of information. The method firstly proposes an entity information representation method based on the Representation learning for fusing entity category information (CEKGRL) model, which introduces the triad structure of related entities in blockchain, then associates them with enterprise business activity categories, and carries out similarity calculation through contextual information to achieve blockchain information consistency assessment. After that, a trustworthiness characterization method is proposed based on information sources, information comments, and information contents, to obtain the trustworthiness assessment of the business. Finally, based on the information trustworthiness characterization, a value assessment method is introduced to assess the total value of business activity information in the blockchain, and a blockchain quality assessment model is constructed. The experimental results show that the proposed model has great advantages over existing methods in assessing inter-block consistency, intra-block activity information trustworthiness and the value of blockchain. [ABSTRACT FROM AUTHOR]

Master–slave blockchain is a novel information processing technology that is domain-oriented and uses efficient cryptography principles for trustworthy communication and storage of big data. Existing indexing methods primarily target the creation of a single-structured blockchain, resulting in extensive time and memory requirements. As the scale of domain data continues to grow exponentially, master–slave blockchain systems face increasingly severe challenges with regards to low query efficiency and extended traceback times. To address these issues, this paper propose a multi-level index construction method for the master–slave blockchain (MLI). Firstly, MLI introduces a weight matrix and partitions the entire master–slave blockchain based on the master chain structure, the weight of each partition is assigned. Secondly, for the master blockchain in each partition, a master chain index construction method based on jump consistent hash (JHMI) is proposed, which takes the key value of the nodes and the number of index slots as input and outputs the master chain index. Finally, a bloom filter is introduced to improve the column-based selection function and build a secondary composite index on the subordinate blockchain corresponding to each master block. Experimental results on three constraint conditions and two types of datasets demonstrate that the proposed method reduce the index construction time by an average of 9.28%, improve the query efficiency by 12.07%, and reduce the memory overhead by 24.4%. [ABSTRACT FROM AUTHOR]

Document-level event extraction aims to extract event-related information from an unstructured document composed of multiple sentences. Existing approaches are not effective due to the challenge of event arguments that are scattered across multi-sentences and they pay more attention to the coreference relationship between entity mentions. However, it is an extremely common phenomenon that there are a large number of crossing sentences pronouns that referring to entity mentions. These pronouns also contain rich semantic information related to events in the document. Therefore, there is still a challenge that how to effectively construct the mention–pronoun coreference relationship and better learn the rich semantic entities representations for DEE. Aiming at the above problems, we propose a novel document-level multi-task learning approach based on coreference-aware dynamic heterogeneous graph network for event extraction, named DMCGEE. Specifically, first, an information enhancement extractor module is constructed to effectively capture multi-types of semantic association information for mentions representations. Second, a mention–pronoun coreference resolution method is proposed to capture mention–pronoun coreference resolution pairs, and a coreference-aware dynamic heterogeneous graph network is constructed to help sentences and mentions representations to focus on the effective global related information, thereby improving the performance of DMCGEE. Experiments show that DMCGEE outperforms the state-of-the-art. [ABSTRACT FROM AUTHOR]

Dynamic graphs are a data structure widely used in representing changeable relationships or connections between different entities. This paper proposes a novel type of node similarity, based on the frequency of connections between nodes to describe the changeable relationships between entities over a period; this has not been considered before as an indication of similarity between two nodes. In other words, if two entities have a history of frequent connections, this means that they have something in common and have a durable relationship. In this paper, durable relationships describe the frequency of connections rather than only the continuous connection between two nodes. Thus, durable relationships are defined in two dimensions: (i) In the dimension of time, they can be categorized based on the length of duration as short-term, medium-term, or long-term relationships; (ii) Based on frequencies of connections over a period, they can be categorized into four statuses (No Relationship, Weak Relationship, In Relationship, and Strong Relationship). Based on this definition of durable relationships, a node similarity measurement algorithm is proposed, to study the status of relationships from a longitudinal study point of view. This method provides a new way to describe the semantics of relationships (such as collaborative relationships, or customer loyalty descriptions) and also gives a practical application of node similarity measurement in a real world, which is to provide a prediction of relationship. Our extensive experiments have shown that the proposed method can effectively describe durable relationships and especially predict future relationships. [ABSTRACT FROM AUTHOR]

Time series classification is a basic task in the field of streaming data event analysis and data mining. The existing time series classification methods have the problems of low classification accuracy and low efficiency. To solve these problems, this paper proposes a T-CNN time series classification method based on a Gram matrix. Specifically, we perform wavelet threshold denoising on time series to filter normal curve noise, and propose a lossless transformation method based on the Gram matrix, which converts the time series to the time domain image and retains all the information of events. Then, we propose an improved CNN time series classification method, which introduces the Toeplitz convolution kernel matrix into convolution layer calculation. Finally, we introduce a Triplet network to calculate the similarity between similar events and different classes of events, and optimize the squared loss function of CNN. The proposed T-CNN model can accelerate the convergence rate of gradient descent and improve classification accuracy. Experimental results show that, compared with the existing methods, our T-CNN time series classification method has great advantages in efficiency and accuracy. [ABSTRACT FROM AUTHOR]

MapReduce and its variants have emerged as viable competitors for big data analysis with a commodity cluster of machines. As an extension of MapReduce, ComMapReduce realizes the lightweight communication mechanisms to enhance the performance of query processing applications for big data. However, different communication strategies of ComMapReduce can substantially affect the executions of query processing applications. Although there is already the research work that can identify the communication strategies of ComMapReduce according to the characteristics of the query processing applications, some drawbacks still exist, such as relative simple model, too much user participation, and relative simple query processing execution. Therefore, an efficient ELM-based two stages query processing optimization model is proposed in this paper, named ELM to ELM (E2E) model. Then, we develop an efficient sample training strategy to train our E2E model. Furthermore, two query processing executions based on the E2E model, respectively, Just-in-Time execution and Queue execution, are presented. Finally, extensive experiments are conducted to verify the effectiveness and efficiency of the E2E model. [ABSTRACT FROM AUTHOR]

Feature selection aims to select a feature subset from an original feature set based on a certain evaluation criterion. Since feature selection can achieve efficient feature reduction, it has become a key method for data preprocessing in many data mining tasks. Recently, many feature selection strategies have been developed since in most cases it is infeasible to obtain an optimal/reduced feature subset by using exhaustive search. Among these strategies, fuzzy rough set theory has proved to be an ideal candidate for dealing with uncertain information. This article provides a comprehensive review on the fuzzy rough set theory and two fuzzy rough set theory based feature selection methods, that is, fuzzy rough set based feature selection methods and fuzzy rough neural network based feature selection methods. We review the publications related to the fuzzy rough theory and its applications in feature selection. In addition, the challenges in the two types of feature selection methods are also discussed. This article is categorized under:Technologies > Machine Learning [ABSTRACT FROM AUTHOR]

Document-level financial event argument extraction aims to extract a set of structured financial information related to particular financial events from a financial document. This task is challenging because there is complex fine-grained semantic information between financial event arguments, such as cross-document, inner-sentence and context semantic information. Existing approaches are still unable to capture these fine-grained financial semantic features well, leading to the low performance defects. Different from these existing approaches, we propose an end-to-end fine-grained document-level financial event argument extraction approach (FGD-FEAE), which defines event argument extraction as a sequence tagging task. In the encoder, a novel multiple granularity attention layer and a long-short term memory network (LSTM) extension layer are proposed and designed to effectively capture these fine-grained financial semantic information. In the decoder, to avoid the financial semantic confusion problem, a conditional random field (CRF) layer is constructed to jointly tag the financial event arguments. Finally, FGD-FEAE is tested on the two benchmark financial datasets, Chinese financial annotation dataset (ChiFinAnn) and English financial press releases (EFPR), and our own Chinese financial project dataset (ChiFD). These datasets contain a large amount of financial corpus information and complete financial event arguments and provide a solid foundation for verifying the general applicability of the proposed FGD-FEAE. Experimental results show that FGD-FEAE can achieve the better performance than the state-of-the-art approaches, and the performance is improved by 4.69, 5.01 and 3.78 on the three actual financial datasets, respectively. [ABSTRACT FROM AUTHOR]

With the rapid development of computer and the Internet techniques, the amount of data in all walks of life increases sharply, especially accumulating numerous high-dimensional big data such as the network transactions data, the user reviews data and the multimedia data. High-dimensional big data mixes the typical features of both high-dimensional data and big data, which has also brought new problems and great challenges for processing and optimizing the high-dimensional big data. In this case, the storage structure of high-dimensional big data is a critical factor that can affect the processing performance in a fundamental way. However, due to the huge dimensionality feature of high-dimensional data, the existing data storage techniques, such as row-store and column-store, are not very suitable for high-dimensional and large scale data. Therefore, in this paper, we present an efficient high-dimensional big data storage structure based on US-ELM, H igh-dimensional B ig Data File , named HB-File . Then, we propose a fuzzy cluster algorithm to differentiate the key dimension and non-key dimension of high-dimensional big data based on US-ELM, which can also gain the clusters of key dimension . After that, we propose the execution and API of HB-File based on the open source implementation of MapReduce, Hadoop system. With the intensive experiments, we show the effectiveness of HB-File in satisfying the storage of high-dimensional big data. [ABSTRACT FROM AUTHOR]

With the development of streaming data processing technology, real-time event monitoring and querying has become a hot issue in this field. In this article, an investigation based on coal mine disaster events is carried out, and a new anti-aliasing model for abnormal events is proposed, as well as a multistage identification method. Coal mine micro-seismic signal is of great importance in the investigation of vibration characteristic, attenuation law, and disaster assessment of coal mine disasters. However, as affected by factors like geological structure and energy losses, the micro-seismic signals of the same kind of disasters may produce data drift in the time domain transmission, such as weak or enhanced signals, which affects the accuracy of the identification of abnormal events ("the coal mine disaster events"). The current mine disaster event monitoring method is a lagged identification, which is based on monitoring a series of sensors with a 10-s-long data waveform as the monitoring unit. The identification method proposed in this article first takes advantages of the dynamic time warping algorithm, which is widely applied in the field of audio recognition, to build an anti-aliasing model and identifies whether the perceived data are disaster signal based on the similarity fitting between them and the template waveform of historical disaster data, and second, since the real-time monitoring data are continuous streaming data, it is necessary to identify the start point of the disaster waveform before the identification of the disaster signal. Therefore, this article proposes a strategy based on a variable sliding window to align two waveforms, locating the start point of perceptual disaster wave and template wave by gradually sliding the perceptual window, which can guarantee the accuracy of the matching. Finally, this article proposes a multistage identification mechanism based on the sliding window matching strategy and the characteristics of the waveforms of coal mine disasters, adjusting the early warning level according to the identification extent of the disaster signal, which increases the early warning level gradually with the successful result of the matching of 1/ N size of the template, and the piecewise aggregate approximation method is used to optimize the calculation process. Experimental results show that the method proposed in this article is more accurate and be used in real time. [ABSTRACT FROM AUTHOR]

A labeled graph is a special structure with node identification capability, which is often used in information networks, biological networks, and other fields. The subgraph query is widely used as an important means of graph data analysis. As the size of the labeled graph increases and changes dynamically, users tend to focus on the high-match results that are of interest to them, and they want to take advantage of the relationship and number of results to get the results of the query quickly. For this reason, we consider the individual needs of users and propose a dynamic Top-K interesting subgraph query. This method establishes a novel graph topology feature index (GTSF index) including a node topology feature index (NTF index) and an edge feature index (EF index), which can effectively prune and filter the invalid nodes and edges that do not meet the restricted condition. The multi-factor candidate set filtering strategy is proposed based on the GTSF index, which can be further pruned to obtain fewer candidate sets. Then, we propose a dynamic Top-K interesting subgraph query method based on the idea of the sliding window to realize the dynamic modification of the matching results of the subgraph in the dynamic evolution of the label graph, to ensure real-time and accurate results of the query. In addition, considering the factors, such as frequent Input/Output (I/O) and network communication overheads, the optimization mechanism of the graph changes and an incremental maintenance strategy for the index are proposed to reduce the huge cost of redundant operation and global updates. The experimental results show that the proposed method can effectively deal with a dynamic Top-K interesting subgraph query on a large-scale labeled graph, at the same time the optimization mechanism of graph changes and the incremental maintenance strategy of the index can effectively reduce the maintenance overheads. [ABSTRACT FROM AUTHOR]