Features of assessing the condition and behavior of low-water bridges

The article describes features of operation and monitoring of low-water bridges, which are found on highways of regional, intermunicipal and local importance. Vibrations of the bridge span are considered in detail, taking into account its interaction with other structural elements and the environment. As a characteristic, the change of which takes into account the change in the state of the bridge structure, it is proposed to use the frequency of natural vibrations. To simulate the dynamic effects of transport and the dynamic behavior of individual elements and the entire structure as a whole, it is proposed to use viscoelastic elements of the Kelvin–Voigt type. When solving the problem, an approach has been implemented that makes it possible to take into account the anisotropic properties of the superstructure associated with various reinforcement along and across the roadway of the bridge, and to present the design scheme of the span not in the form of a beam supported at the edges with the help of hinges or viscoelastic dampers, but in the form of a plate, which can have different fxing conditions along the entire contour. The use of the proposed model and approach will make it possible to obtain the necessary data on the state of low-water bridges, for which there is often no possibility of visual inspection or instrumental inspection from the lower side of the bearing part of the superstructure. By the values of the frequency of natural vibrations, it is possible to estimate the water level above the low-water period and predict food situations, during which the roadway of the low-water bridge may be fooded.

Electrically Induced Liquid–Liquid Phase Transition in a Floating Water Bridge Identified by Refractive Index Variations

A horizontal electrohydrodynamic (EHD) liquid bridge (also known as a “floating water bridge”) is a phenomenon that forms when high voltage DC (kV·cm−1) is applied to pure water in two separate beakers. The bridge, a free-floating connection between the beakers, acts as a cylindrical lens and refracts light. Using an interferometric set-up with a line pattern placed in the background of the bridge, the light passing through is split into a horizontally and a vertically polarized component which are both projected into the image space in front of the bridge with a small vertical offset (shear). Apart from a 100 Hz waviness due to a resonance effect between the power supply and vortical structures at the onset of the bridge, spikes with an increased refractive index moving through the bridge were observed. These spikes can be explained by an electrically induced liquid–liquid phase transition in which the vibrational modes of the water molecules couple coherently.

Adjustable diffusion enhancement of water molecules in a nanoscale water bridge

Adjustable enhanced diffusion coefficients in a water bridge are 4 times larger than those in bulk water.