The cooperation of radar and communications becomes important in vehicular environments due to the demand for radar-assisted communications or communications-assisted radar. In this paper, the tradeoff between bi-static radar and communications in a joint radar-communications setting is studied. We propose three schemes by using time division, superposition or their mixture. For each scheme, three optimization problems are formulated to maximize either the probability of detection for radar subject to a minimum communications rate, the communications rate subject to a minimum probability of detection for radar, or a combined measure of tradeoff. Specifically, given a fixed amount of total time or power for both communications and radar, the optimal power allocation and/or time allocation between radar and communications are derived. Numerical results show that the superposition scheme outperforms the time division scheme and the mixture scheme with considerable performance gains. They also show that the surveillance channel in radar and the communications channel are more important than the direct channel in radar.

At present, with the increasingly growing application of Internet of Things, virtualization and intelligent technologies, and the maturity of smart campus systems, campus card technology based on radio frequency identification (RFID) has developed rapidly. Due to the convenience of use, it is widely used in dormitory access control system, book borrowing system, attendance system, payment system, etc. Because the data carried by the RFID card is more and more complex, the requirements for its security are getting higher and higher. In order to solve the problem of identity authentication and privacy protection of the RFID application existed in the digital campus in recent years, an improved mutual authentication protocol in mobile RFID for smart campus is put forward by analyzing and studying existing smart campus authentication protocols based on hash algorithm, which uses the technology of random number S and time stamp T. This protocol implements mutual authentication among the tag, reader and backend database without the premise that the signal path between the database and reader communication is a safe signal path, and can effectively resist counterfeit attack, replay attack, position tracking attack, de-synchronization attack, eavesdropping attack, denial of service attack (DoS) and man-in-the-middle attack (MTM), it can also guarantee forward security. Due to the large data operations and storage has been transferred to readers and backend data, the protocol is formally proved to have a strong reliability and a good security. In addition, through the comparison with other existing authentication protocols on the resident variable storage overhead, the cost of computing complexity and the security performance, the authentication protocol proposed in this paper has better storage and calculation performance, and it can better satisfy the security requirements in mobile RFID applications for smart campus in the future and has a good application prospect.

Hyperspectral imaging technology is a research hotspot in the field of cultural heritage protection. It can be used to quickly and noninvasively obtain detailed spectral information from the surfaces of cultural relics of different categories. We can intuitively analyse pigment compositions, line characteristics, painting skills and patterns using spectral information. Hyperspectral imaging has high scientific significance and application value for the protection, restoration and research of ancient murals and other cultural relics. In this study, a mural from Daheitian hall in the Qutan temple, Qinghai Province, China, was used as a sample. The hyperspectral data were acquired and analysed for several purposes. Pigment spectral matching and abundance inversion were carried out to obtain the pigment distribution. These data were enhanced by continuum removal and histogram stretching to obtain hidden information. The dark channel prior, Criminisi and Retinex methods were used to virtually restore the image of the mural. The results indicated that by using hyperspectral imaging data, the constructed pure pigment spectrum library and suitable approaches, the types and distributions of mural pigments can be quantitatively analysed, and the lines in murals can be extracted. Hyperspectral images are helpful for identifying information hidden by pigments or surface materials. Mural images can be enhanced, and hidden information can be highlighted using enhancement methods, such as continuum removal and histogram linear stretching. In addition, hyperspectral imaging data have unique advantages in the restoration of mural images, and the combination of defogging methods and image inpainting algorithms can realize the virtual restoration of mural images. In brief, hyperspectral imaging technology was found to have a highly favourable effect on pigment analysis, line extraction, information enhancement, hidden information extraction and the virtual restoration of ancient murals.