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The adoption of blockchain technology can guarantee the safe and reliable storage of IoT data. In the agricultural products traceability system based on blockchain + Internet of Things, the storage method used in most existing schemes is to save the original data in the off-chain database system, but the real data cannot be agreed on the blockchain. However, if all the data in the production Internet of things are stored directly on the blockchain, it will cause great storage pressure. In order to balance the reliability and storage pressure of the IoT data stored on blockchain in the agricultural industry chain, a high-value density blockchain compression storage scheme for agricultural IoT data is proposed. This paper connects all production links of the agricultural product chain based on consortium blockchain and collects field data based on the Internet of Things composed of sensors. Firstly, a blockchain storage framework for agricultural Internet of Things data is proposed. The collected Internet of Things data is summarized through gateways or edge server devices before being stored in the blockchain. The value density of on-chain data is increased by compression method. An adaptive lossy compression method with outliers is designed for the data compression process. The agricultural IoT data is divided into normal values and outliers based on the outlier separation method. According to the time correlation between sensor data and the sparse of abnormal data, an adaptive compression algorithm for normal data and outlier data compression algorithm is designed to compress normal data and outlier data respectively. Compressed data are stored in the blockchain instead of original data, reducing storage space occupation; The application service platform can obtain the data on the blockchain and reconstruct the data that meets the accuracy need. The results of experiments show that when the proposed scheme is used for data compression, k values can be adaptively selected for different data sets, and good compression effects can be obtained, on-chain storage space can be reduced, and the value density of data can be improved, satisfying the reconstruction accuracy of users. This method has a good compression effect for data with low change frequency, such as temperature and humidity data, but fails to achieve a high compression effect for data with high change frequency such as wind speed data. In the scheme, storing data on the blockchain can solve the problem of traceability data caused by off-chain storage. In view of the storage redundancy caused by storing all the data on the blockchain, lossy compression method is adopted to reduce the data volume and improve the value density of on-chain data within the acceptable error range of the Internet of Things data provider. Experiments show that suppose the compression ratio of normal data is 10:1, this method saves about 85% of on-chain storage space and increases the corresponding data value density by about 85%. The scheme only stores data with a compression factor through the blockchain network, reducing the storage and management overhead of on-chain data. At the same time, the scheme has the characteristics of availability, data traceability and non-repudiation. Apart from being a mere technical solution, this research endeavor emerges as a robust response to the imperatives of secure and reliable IoT data storage within the agricultural product traceability landscape. Looking ahead to the agricultural product traceability scenario based on blockchain, this innovative solution calls for the possibility of harmonious integration with technologies such as sidechain and data offloading. This integration will further mitigate blockchain storage redundancy while ensuring data consensus on the blockchain. The ultimate goal is to ensure the transparency and traceability of the entire agricultural product data traceability process. With the development of the industry and the continuous progress of the technology field, it provides technical support for the realization of distributed agricultural Internet of Things data compression storage. [ABSTRACT FROM AUTHOR]

The purchase and maintenance of agricultural machinery can be one of the most formidable challenges for smallholder farmers in recent years. The agricultural machinery socialization services can effectively improve the quality of agricultural production through integration and redistribution of farm machinery resources. However, the traditional agricultural machinery socialization systems tend to confine the resources within their respective individual systems. The participation of tasks and workers was limited in the matching processes of other systems. Thus, a federated platform is necessary to combine the different agricultural machinery services in order to facilitate the development of agricultural modernization by sharing the resources for cross-platform matching. But, the implementation of the federated platform can cause significant security concerns. For example, there is a potential risk of sensitive information leakage, when the data is shared across different platforms, resulting in serious privacy violations. Additionally, the centralized servers responsible for the task-matching services cannot always return accurate predicts. Therefore, it is crucial to explore safe and reliable privacy matching in the federated platform. In this study, a privacy-preserving matching scheme was introduced using CP-ABSE. The farming tasks were matched to the optimal farm mechanics. The blockchain was then employed as the underlying platform to establish the federation of agricultural machinery service platforms. The blockchain ledger was selected to record the task information of each platform and the transferring data of cross-platform, in order to avoid tampered data. Furthermore, each agricultural machinery service maintained the autonomy to access and then utilize the potential resources from other cooperation platforms. CP-ABSE technology was used to ensure the confidentiality of sensitive data in both tasks and farmers. As such, an accurate matching was achieved under ciphertext conditions. The matching farming tasks and agricultural mechanics were transformed into a task access control and keyword-based search. Specifically, the matching between farming task types and mechanics' interests could be transformed to the match between encrypted keywords and ciphertext indexes by the matching scheme. The fine-grained access control between multiple data owners and users was taken as the matching between farming operation requirements and farm services available from mechanics. Simultaneously, the service code was deployed onto the smart contracts. Different agricultural machinery service platforms published the encrypted task requirements on the blockchain using upload smart contracts. Smart contracts were then matched to perform the secure taskmatching services. This approach replaced the need for a centralized server, such as the single points of failure and tampering with the match data. The security analysis showed that the matching scheme was achieved in the integrity and confidentiality of sensitive data that was shared with other cooperative platforms. Additionally, the ciphertext of tasks stored on the blockchain ledger possessed indistinguishability, which could resist the selective plaintext attacks. Finally, a prototype test system was constructed using Hyperledger Fabric, in order to verify the effectiveness of the matching scheme. The average latency of the matching smart was contracted around 250ms, indicating that the operation efficiency of the algorithm fully met the basic application requirements of the federated platform. The scheme can be expected to effectively achieve the security of sensitive data and cross-platform task matching in the federation platforms of agricultural machinery service. [ABSTRACT FROM AUTHOR]

Objective The CO2 absorption process under high gravity environment is simulated so as to provide guidance for the optimization of experimental process parameters. Methods An Aspen Plus calculation model for CO2 absorption using NaOH alkaline solution under high gravity was established, and the influence factors on the CO2 removal rate were investigated. Results While the high gravity reactor was equivalent to a conventional packed tower through the equivalent conversion method, the influence of sodium hydroxide mass fraction, solution feed rate and pressure on the CO2 removal rate were similar to that of the high gravity laboratory value, but the simulated value was only about 1/2 of the experimental value. The corrected simulation results were close to the experimental values, and the average deviation was only 0. 77%. Conclusions The established CO2 absorption model under high gravity environment is accurate and reliable, which can provide some directional guidance for subsequent experiments. [ABSTRACT FROM AUTHOR]

Agricultural product supply chain and blockchain are closely integrated with the continuous acceleration of agricultural modernization. The clustered supply chain has gradually developed from a single supply chain in recent years. There is heat competition among peer enterprises in the clustered agricultural product supply chain blockchain. Among them, the data on the blockchain is publicly available to all participants. The private data on the chain has been adopted as an encrypted storage model, in order to protect users' privacy. The existing single-department supervision scheme is unsuitable for the complex cluster agricultural supply chain. The multi-sector supervision can be expected to serve as a promising way in the current reality. However, multi-department supervision is still challenging to ensure the sharing of encrypted data on the chain without redundant information for irrelevant departments. It is a high demand to improve supervision efficiency and credibility. Fortunately, the ciphertext-policy attribute-based encryption (CP-ABE) can be a one-to-numerous encryption, essentially a public key encryption system. The CP-ABE can realize the sharing of data for the users with specified attributes suitable for the application environment of multi-department supervision of the blockchain in the clustered agricultural supply chain. In this research, a multi-department supervision scheme was proposed in the verifiable blockchain ciphertext policy for the cluster agricultural supply chains using CP-ABE. A chain of custody was set up outside the business chain, including the supervisors from various departments to facilitate the management of supervisors. The chain of custody managed data on the business chain through “cross-chain governance.” Different supervision strategies were set for the data on the chain, according to the data type. The administrator of the supervision department was set as the department's supervisor to supervise the specific data of the specific chain. According to the supervision strategy on the chain, the enterprise users encrypted the data using CP-ABE to realize the disclosure of data for privacy. A CP-ABE-based access tree verification scheme was designed to combine the smart contracts and supervision strategies, and then to verify the CP-ABE access tree before the data was uploaded to the chain, in order to ensure that the data was available to the designated supervisor. The direct use of CP-ABE was inefficient for data encryption. Therefore, hybrid encryption was used to encrypt and share the data. The specific implementation was to encrypt the original data with symmetric encryption and then use the CP-ABE to encrypt the symmetric encryption key. A supervision prototype system was constructed under the blockchain ciphertext of the clustered agricultural supply chain using Hyperledger Fabric. The system was tested in two aspects of function and performance. The functional test showed that the system fully met the needs of essential multi-department supervision. The performance test showed that each time the number of supervisors in the supervision strategy increased by 10, while the average on-chain time was extended by about 500 ms, and the average throughput was 438 (number of transactions/s, transactions/s). When the number of supervisors for a single data type of a single enterprise was within a reasonable range, the clustered system was adept to the multi-department supervision under the condition of the primary clustered agricultural supply chain blockchain ciphertext-application requirements. Security analysis indicated the high-security system. As such, this scheme can be expected suitable for the multi-departmental, specialized, and fine-grained supervision of data on the blockchain under data encryption. The pressure of regulators can be inspired by the development of blockchain supervision of cluster agricultural supply chains. [ABSTRACT FROM AUTHOR]

A cluster of agricultural products supply is characterized by long and multiple chains, decentralized production, multi-source heterogeneous data, and complex network structures. A multiple chain blockchain can be widely expected in the demand for the blockchain traceability of cluster agricultural products supply chain. However, a complete traceability chain is still lacking in the multi-chain blockchain network, where the different blockchains were isolated from each other, due to the data breaks in the different alliances. In this study, an improved blockchain traceability model was proposed for the cluster of agricultural products supply chain using blockchain relay technology, in order to explore the information islands between alliances for the information connection of the entire supply chain. The business composition was also analyzed to open the upstream and downstream blockchains of the supply chain. A relay multi-chain blockchain topology was then constructed for the cluster agricultural products supply chain. The relay nodes were selected to register the related information in the application blockchain, such as cross-blockchain routing, and endorsement strategy. The blockchain was firstly initialized to interact with the destination blockchain through the relay nodes and cross-blockchain routing. A hyperledger fabric endorsement strategy was then used to verify the cross-blockchain transactions. Taking the cluster of kiwifruit supply chain as an example, the prototype system was finally designed and implemented to determine the function, performance, and scalability of the model. The integrity, credibility, and validity of cross-blockchain function were achieved to effectively solve the information chain disconnection in the multi-chain blockchain traceability. The maximum writing throughput (561.8 transactions/s) of system data was much higher than that of single chain blockchain (118.1 transactions/s), indicating the excellent performance of the model. The average data writing delay was 1.49 s, which was better than that of a single chain blockchain of 5.92 s. The number of blockchains in the system increased dynamically to flexibly respond to the changes in the cluster supply chains, according to the business needs. Consequently, the improved model can fully realize the traceability of the cluster agricultural products supply chain. The finding can provide a strong reference for the expansion of the blockchain traceability network, in order to realize the unified layout and coordinated development in the industry cluster of agricultural products supply. [ABSTRACT FROM AUTHOR]