Vector Map Encryption Algorithm Based on Double Random Position Permutation Strategy

Encryption of vector maps, used for copyright protection, is of importance in the community of geographic information sciences. However, some studies adopt one-to-one mapping to scramble vertices and permutate the coordinates one by one according to the coordinate position in a plain map. An attacker can easily obtain the key values by analyzing the relationship between the cipher vector map and the plain vector map, which will lead to the ineffectiveness of the scrambling operation. To solve the problem, a vector map encryption algorithm based on a double random position permutation strategy is proposed in this paper. First, the secret key sequence is generated using a four-dimensional quadratic autonomous hyperchaotic system. Then, all coordinates of the vector map are encrypted using the strategy of double random position permutation. Lastly, the encrypted coordinates are reorganized according to the vector map structure to obtain the cipher map. Experimental results show that: (1) one-to-one mapping between the plain vector map and cipher vector map is prevented from happening; (2) scrambling encryption between different map objects is achieved; (3) hackers cannot obtain the permutation key value by analyzing the pairs of the plain map and cipher map.

Quantitative blood flow estimation in vivo by optical speckle image velocimetry

Speckle based methods are popular non-invasive, label-free full-field optical techniques for imaging blood flow maps at single vessel resolution with a high temporal resolution. However, conventional speckle approach cannot provide an absolute velocity map with magnitude and direction. Here, we report a novel optical speckle image velocimetry (OSIV) technique for measuring the quantitative blood flow vector map by utilizing particle image velocimetry with speckle cross-correlations. We demonstrate that our OSIV instrument has a linearity range up to 7 mm/s, higher than conventional optical methods. Our method can measure the absolute flow vector map at up to 190 Hz without sacrificing the image size, and it eliminates the need for a high-speed camera/detector. We applied OSIV to image the blood flow in a mouse brain, and as a proof of concept, imaged the real-time dynamic changes in the cortical blood flow field during the stroke process in vivo. Our wide-field quantitative flow measurement OSIV method without the need of tracers provides a valuable tool for studying the healthy and diseased brain.

Method for Protection of Copyright on Vector Data

The paper proposes a method of copyright protection for vector maps, based on the embedding of raster digital watermarks. The method combines original ideas, namely, a vector data watermarking approach that does not distort the coordinate information of vector objects and embedding of noise-like images that encode a binary sequence. The use of noise-like carrier allows to simplify the verification procedure, and also to ensure the resistance of the hidden bit sequence to distortions, including interpolation errors. In comparison with previous investigations made by the authors when solving problems of vector data protection, the robustness of the embedded noise-like digital watermarks has been significantly increased by developing a new algorithm for detection of the binary sequence hidden in the spectrum of a noise-like image. The purpose of the experimental studies was to assess the attainable probability of correct sequence extraction for various parameters and embedding conditions. The study of information capacity showed that the potential amount of information embedded in each polygon without distorting the watermark sequence depends on the type of a map, namely on the number of vertices that make up each polygon. An experimental study on robustness against potentially possible transformations aimed at maliciously deleting the digital watermark from the vector map is performed. The developed method demonstrates resistance to affine transformations, cropping, addition, removal and reordering of vertices / objects, and, thus, seems to be the optimal solution to the problem of copyright protection for vector data. The analysis of the method quality according to the criteria of accuracy, durability, information capacity, and computational complexity is performed. The results of all conducted studies confirm the efficiency and the effectiveness of the proposed method for vector map protection, as well as its distinct advantage over the prior art.

Research on Navigation and Positioning Technology of Intelligent Accompanying Tool Car in Dispatching Automation Computer Room

In view of the wide variety of equipment in the dispatch automation machine room and the dense arrangement of cabinets, a navigation technology suitable for the dispatch automation machine room is proposed on the intelligent companion tool cart. In this paper, three sensors of ultrasonic, infrared and lidar are designed to form an intelligent neural sensor, and the information received by the intelligent neural sensor is calculated to generate a vector map through a software algorithm. At the same time, a plane coordinate network is established. The grid coordinate unit accuracy is 0.1cm. At the same time, the concept of “virtual fence” was put forward to fix the workers at the working point, which increased the safety of work. Subsequently, an experimental test of positioning and navigation of the tool cart was carried out. The experimental results showed that the tool cart can accurately locate and generate a vector map with an accuracy error of less than 10cm. The navigation method has a good application effect and has a good promotion value.