High-Frequency Magnetoimpedance (MI) and Stress-MI in Amorphous Microwires with Different Anisotropies

Magnetoimpedance (MI) in Co-based microwires with an amorphous and partially crystalline state was investigated at elevated frequencies (up to several GHz), with particular attention paid to the influence of tensile stress on the MI behavior, which is called stress-MI. Two mechanisms of MI sensitivity related to the DC magnetization re-orientation and AC permeability dispersion were discussed. Remarkable sensitivity of impedance changes with respect to applied tensile stress at GHz frequencies was obtained in partially crystalline wires subjected to current annealing. Increasing the annealing current enhanced the axial easy anisotropy of a magnetoelastic origin, which made it possible to increase the frequency of large stress-MI: for 90mA-annealed wire, the impedance at 2 GHz increased by about 300% when a stress of 450 MPa was applied. Potential applications included sensing elements in stretchable substrates for flexible electronics, wireless sensors, and tunable smart materials. For reliable microwave measurements, an improved SOLT (short-open-load-thru) calibration technique was developed that required specially designed strip cells as wire holders. The method made it possible to precisely measure the impedance characteristics of individual wires, which can be further employed to characterize the microwave scattering at wire inclusions used as composites fillers.

Recycled PET ((Poly) Ethylene-erephthalate) used as straps for rebar binding

Recycling has an important role in modern production and in environment preservation. Introduction of recycled PET ((Poly) Ethylene-terephthalate) as straps for reinforcement bars in concrete construction elements can help these important issues. By using an experimental method it is shown that PET straps made with minimal investment, on site and with manual production can replace "annealed" wire as element for connection of reinforcement bars. An overview of some regulation and procedures is presented and used for eligibility assessment of the proposed straps made of recycled material. Also an overview of commonly used connections is given so it can be compared with the proposed ones.

Analysis of strength ratio of different hop strings

In plant-growing, minimization of impurities in the final product plays a more and more important role. One of the risky places that can influence the final purity of granules in hop growing is the way of hop strings hanging on the trellis supporting wire. The ideal state is when hop-field supporting wires stay clean and without any attachments after the hop vines had been pulled down. The article deals with different variants of hop strings hanging, a description of the measuring equipment, and a measurement of the pulling force itself at a field test, and a realization of break tests in laboratory conditions with both new and used wires and twines. Two-year results of field tests proved advantageousness of the hop string hanging variant in combination of a black annealed wire of 1.06 mm in diameter with a polypropylene twine of strength labelled as 12,500 in the form of a simple attachment, as well as variants combining the same wire and a jute twine labelled 2,200 × 2 in the form of a double attachment. Other variants using attachments made of jute or sisal are unsuitable due to a large number of fallen hopvines in vegetation period. Paper attachments will be put to further tests.