The precise location of the needle tip is critical in robot-assisted needle-based percutaneous interventions. An automatic needle tip measuring system based on binocular vision technology with the advantages of non-contact, excellent accuracy and high stability is designed and evaluated. First the measurement requirements of the prostate intervention robot are introduced. A laser interferometer is used as the reference for measuring the position of the needle tip whose relative position variation is described as the needle tip distance in the time domain. The parameters of the binocular cameras are obtained by Zhang’s calibration method. Then a robust needle tip extraction algorithm is specially designed to detect the pixel coordinates of the needle tip without installing the marked points. Once the binocular cameras have completed the stereo matching, the 3D coordinates of the needle tip are estimated. The measurement capability analysis (MCA) is used to evaluate the performance of the proposed system. The accuracy of the system can be controlled within 0.3621 mm. The agreement analysis is conducted by the Bland–Altman analysis, and the Pearson correlation coefficient is 0.999847. The P/T ratio value is 16.42% in the repeatability analysis. The results indicate that the accuracy and stability of the binocular vision needle tip measuring system are adequate to meet the requirement for the needle tip measurement in percutaneous interventions.

In the research of long-time operating road bridge superstructures, it should note that when the internal forces in the beam elements reach specific values, the stiffness of the cross-section of these elements should decrease. Besides that, if there are damaged places in the beam-element of the road bridge superstructures, the element could not work normally, and the redistribution of internal forces between elements in the whole system would happen. This phenomenon was not taken into account in the initial design calculation. In practice, it shows that many road bridges are subjected to greater loads than the calculated loads in the design process, but they still normally operate. This article proposes the other limit state criteria in evaluating the load capacity reserve of road-bridge superstructures using nonlinear analysis based on nonlinear deformational models of modern construction codes. The proposed calculation procedure is established to explain the load capacity reserve of long-time operating road bridge superstructures in the case of the lack of experimental evaluation. From the obtained results, the suitable limit state criteria for road bridge superstructures are suggested, and the conclusions about the accuracy of the proposed approach of nonlinear structural analysis are recommended.

Wireless Sensor Networks (WSNs) have existed for many years and had assimilated many interesting innovations. Advances in electronics, radio transceivers, processes of IC manufacturing and development of algorithms for operation of such networks now enable creating energy-efficient devices that provide practical levels of performance and a sufficient number of features. Environmental monitoring is one of the areas in which WSNs can be successfully used. At the same time this is a field where devices must either bring their own power reservoir, such as a battery, or scavenge energy locally from some natural phenomena. Improving the efficiency of energy harvesting methods reduces complexity of WSN structures. This survey is based on practical examples from the real world and provides an overview of state-of-the-art methods and techniques that are used to create energyefficient WSNs with energy harvesting.