When the technology of wireless sensor network is applied to ocean monitoring, the ocean underwater monitoring system will become a distributed network system. That could improve the level of ocean monitoring significantly. But most of the current ocean monitoring equipments work independently, and it is difficult to form them into a sensor network. To set up a sensor network, electric energy supply and data transmission are the chief problem, especially for the underwater sensor nodes. To solve this problem, a new method for contactless power and data transmission is proposed. It operates with the principle of electromagnetic coupling. Power and data are transmitted through a mutual channel. This channel is realized by the structure of a two-stage electromagnetic coupler. Here, steel rope is used as the closed steel ring to compose an electromagnetic coupler. Since steel rope is widely used in the current underwater equipments, the transmission channel of power and data can be realized without changing the existing structure. Furthermore, because of contactless transmission the sensor network has good expansibility and convenient configuration of its nodes for underwater applications. A voltage transformation model for the two-stage electromagnetic coupler is constructed and the transmitting principle of power and data is analyzed based on the model. According to the energy transmission efficiency and the bit error rate, an experimental prototype is designed and fabricated. Finally, the prototype testing of power transmission, data transmission, and reactive power compensation are carried out. The experimental results show that the proposed method for contactless power and data transmission is feasible and it is suitable for the application of underwater sensor nodes.

A novel virtual phase calibrating model plane method for coordinate calibration in fringe projection profilometry is presented in this paper. Plane (X-axis and Y-axis) calibration and height (Z-axis) calibration are studied respectively. The virtual phase calibrating model plane method is designed to calibrate the coordinates. Experimental results show that the proposed calibration procedure using the virtual phase calibrating model plane method is more efficient in that it needs only to grab and process one series of images of the model plane, whereas the traditional calibration method requires at least two series of images.

Calibration is one of the most important technologies for line-structured light vision sensor. The existing calibration methods depend on special calibration equipments, whose accuracy determines the calibration accuracy. It is difficult to meet the requirements of universality and field calibration with those methods. In order to solve these problems, a new calibration method based on the combined target for line-structured light multi-vision sensor is proposed. Each line-structured light multi-vision sensor is locally calibrated by combined target with high precision. On the basis of global calibration principle and the characteristics of the combined target, global calibration and local calibration are unified. The unification avoids the precision decrement caused by coordinate transformation. And the occlusion problem of 3D reference objects can be avoided. An experimental system for 3D multi-vision measurement is set up with two sets of vision sensor and its calibration matrix is obtained. To improve the calibration accuracy, the method of acquiring calibration points with high precision and error factors in calibration are analyzed. After being calibrated, the experimental system is finally tested through a workpiece measurement experiment. The repeatability of this system is 0.04 mm, and it proves that the proposed calibration method can obtain high precision. Moreover, by changing the structure of the combined target, this calibration method can adapt to the different multi-vision sensors, while the accuracy of the combined target is still guaranteed. Thus, this calibration method has the advantages of universality and field calibration.

Understanding the high water adhesion of rose petals is of great significance in artificial surface design. With all-atom molecular dynamics simulation, the wettability of nanoscale wrinkles was explored and compared to that of nanoscale strips with favorable hydrophobicity. The dewetting and wetting of gaps between nanoscale structures represent the Cassie–Baxter (CB) and Wenzel (WZ) states of the macroscopic droplet deposited on the textured surface, respectively. We uncovered the intermediate state, which is different from the CB and WZ states for wrinkles. Structures and free-energy profiles of metastable and transition states under various pressures were also investigated. Moreover, free-energy barriers for the (de)­wetting transitions were quantified. On this basis, the roles of pressure and the unique structures of nanoscale wrinkles in the high water adhesion of rose petals were identified.

A new image fusion method based on Contourlet transform and an improved pulse coupled neural network (PCNN) is introduced in this paper. The input infrared and visible images are processed with Contourlet decomposition which has multi-scale and multi-directional characteristics. The PCNN algorithm deriving from the neurophysiology is optimized in order to be compatible with the image fusion strategy. Owning to the global coupling and pulse synchronization characteristic of PCNN, this new fusion strategy utilizes the global features of source images and has several advantages in comparison with the traditional methods based on the single pixel or regional features. Multiple criteria and statistical indicators regarding different aspects of image quality are presented for objective and quantitative evaluation of the fused images to understand the performance of image fusion algorithms. Experimental result shows that the new method can improve the quality of image fusion and can achieve an ideal fusing effect. The method would find its application in the aspects of optical imaging, target detection and safety monitoring, etc.

Micro-force measurement with high resolution, accuracy, and reliability is of interest to a broad range of applications including gravitational wave detection, intelligent healthcare, bionic robot, and micromanipulation. Herein, the research development in recent years of micro-force sensors based on various principles is reviewed thoroughly, presenting the characteristics and applications, as well as summarizing their advantages and limitations. The indispensable component of force sensors, elastic sensitive elements, is underlined. Next, four kinds of not widely used but promising sensors are also introduced briefly. Finally, the traceable reference forces are analyzed, concluding with a future perspective into the corresponding challenges and opportunities of micro-force sensors for future research. This review aims at providing references for developing micro-force sensors and improving their performance.

Reversible switch between underwater superaerophilicity and superaerophobicity on the superhydrophobic nanowire-haired mesh for controlling underwater bubble wettability AIP Advances 8, 045001 (2018); https://doi.org/10.1063/1.5018864The effect of surface wettability on the performance of a piezoelectric membrane pump AIP Advances 8, 045010 (2018) The interaction force is very important in the study of the contact process of droplets and super-hydrophobic substrates. Accurate interaction force measurement in the air has far-reaching impact on industrial production and biomimetic field. However, limited by the evaporation of small droplets, interaction force can only be measured in the liquid by AFM and other devices. A millimetric cantilever was used to make it possible to measure the interaction between droplets and super-hydrophobic substrates in the air. The optical lever was calibrated with the electrostatic force. The super-hydrophobic substrates were fabricated using nano particles and copper grids. We finally acquired the interaction force and wetting time between the droplet and super-hydrophobic substrates with different grid fractions and similar contact angle. The results showed that the interaction force decreased with the increase of the grid fraction. These would open a new way of understanding the mechanism of hydrophobic. © 2018 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license

Optical glass is the most widely used optical material. It is necessary to measure its geometric characteristic quickly and reliably to meet the quality of optical glass. A vision measuring system combining photoelectric autocollimation system with high-precision rotary stage is designed to measure the parallelism and angle of optical glass plane. A novel method is proposed to overcome the difficulty of measuring parallelism of optical glass. The model of parallelism and angle measurement is established and the feasibility is analyzed. The image processing algorithm combining Steger algorithm with the least square method is selected. The uncertainty of angle measurement system for angle measurement is 3.0″. The system can solve the problem of measuring the angle of optical glass with high precision and has important significance for optical system.