Abstract: A fly ash-based fire-prevention and extinguishing material with carbon dioxide mineralized and stored, and a preparation method thereof are provided. The preparation method includes: separately weighing 100 parts to 120 parts of water, 1 part to 3 parts of a solid strong alkali, and 20 parts to 40 parts of a fly ash as raw materials, pouring the raw materials into a reactor successively to obtain a resulting mixture, and stirring the resulting mixture at a high rotational speed; adding 10 parts to 20 parts of a solubilizing agent to the reactor, sealing the reactor, introducing carbon dioxide to the reactor at room temperature to maintain a carbon dioxide pressure to obtain a resulting slurry, and stirring the resulting slurry at a high rotational speed; and further introducing carbon dioxide into the reactor to increase the carbon dioxide pressure, and stirring the resulting slurry at a low rotational speed.

Abstract: Methods and systems of providing enhanced security to an access-controlled area are disclosed herein. In one implementation a user device generates a signal from which features are extracted to generate a device fingerprint. The features of the signal may be rare, or in some cases unique, to a particular user device such that the use of user device with a known device fingerprint may thwart a relay attack on the access-controlled area. The features of the signal may be related to manufacturing variations between user devices, even devices of the same model. The variations may be related to variations in an electro-mechanical structure of a motion sensor between two user devices. The variations in the electro-mechanical structure may cause variations in a capacitance sensed by the motion sensor. Features of the signal may be analyzed in the frequency or time domains to generate the device fingerprint.

Abstract: Methods and systems of providing enhanced security to an access-controlled area are disclosed herein. In one implementation a user device generates a signal from which features are extracted to generate a device fingerprint. The features of the signal may be rare, or in some cases unique, to a particular user device such that the use of user device with a known device fingerprint may thwart a relay attack on the access-controlled area. The features of the signal may be related to manufacturing variations between user devices, even devices of the same model. The variations may be related to variations in an electro-mechanical structure of a motion sensor between two user devices. The variations in the electro-mechanical structure may cause variations in a capacitance sensed by the motion sensor. Features of the signal may be analyzed in the frequency or time domains to generate the device fingerprint.