F-structure model of overlying strata for dynamic disaster prevention in coal mine

The rupture and movement scope of overlying strata upon the longwall mining face increased sharply as the exploitation scale and degree growing recently,and the spatial structure formed by fractured strata became much more complex.The overlying strata above the working face and adjacent gobs would affect each other and move cooperatively because small pillar can hardly separate the connection of overlying strata between two workfaces,which leads to mining seismicity in the gob and induces rockburst disaster that named spatial structure instability rockburst in this paper.Based on the key stratum theory,the F-structure model was established to describe the overlying strata characteristic and rockburst mechanism of workface with one side of gob and the other side un-mined solid coal seam.The results show that F-structure in the gob will re-active and loss stability under the influence of neighboring mining,and fracture and shear slipping in the process of instability is the mechanism of the seismicity in the gob.The F-structure was divided into two categories that short-arm F and long-arm F structure based on the state of strata above the gob.We studied the underground pressure rules of different F-structure and instability mechanism,thus provide the guide for prevention and control of the F-structure spatial instability rockburst.The micro-seismic system is used for on-site monitoring and researching the distribution rules of seismic events,the results confrmed the existence and correct of F-spatial structure.At last specialized methods for prevention seismicity and rockburst induced by F-structure instability are proposed and applied in Huating Coal Mine.

Dynamic Encryption and Secure Transmission of Terminal Data Files

Data is the last defense line of security,in order to prevent data loss,no matter where the data is stored,copied or transmitted,it is necessary to accurately detect the data type,and further clarify the form and encryption structure of the data transmission process to ensure the accuracy of the data,so as to prevent data leakage,take the data characteristics as the core,use transparent encryption and decryption technology as the leading,and According to the data element characteristics such as identity authentication,authority management,outgoing management,file audit and external device management,the terminal data is marked with attributes to form a data leakage prevention module with data function,so as to control the data in the whole life cycle from creation,storage,transmission,use to destruction,no matter whether the data is stored in the server,PC or mobile device,provide unified policy management,form ecological data chain with vital characteristics,and provide comprehensive protection system for file dynamic encryption transmission,such as prevention in advance,control in the event,and audit after the event,so as to ensure the security of dynamic encryption in the process of file transmission,ensure the core data of the file,and help the enterprise keep away from the risk of data leakage.

Fast and Efficient Security Scheme for Blockchain-Based IoT Networks

Internet of Things(IoT)has become widely used nowadays and tremendous increase in the number of users raises its security requirements as well.The constraints on resources such as low computational capabilities and power requirements demand lightweight cryptosystems.Conventional algorithms are not applicable in IoT network communications because of the constraints mentioned above.In this work,a novel and efficient scheme for providing security in IoT applications is introduced.The scheme proposes how security can be enhanced in a distributed IoT application by providing multilevel protection and dynamic key generation in the data uploading and transfer phases.Existing works rely on a single key for communication between sensing device and the attached gateway node.In proposed scheme,this session key is updated after each session and this is done by applying principles of cellular automata.The proposed system provides multilevel security by using incomparable benefits of blockchain,dynamic key and random number generation based on cellular automata.The same was implemented and tested with the widely known security protocol verification tool called Automated Validation of Internet Security Protocols and Applications(AVISPA).Results show that the scheme is secure against various attacks.The proposed scheme has been compared with related schemes and the result analysis shows that the new scheme is fast and efficient also.