Magnetic Field Technique Research Articles

Magnetic Field and Agriculture Sustainability

Agriculture's sustainability depends on the need to use practices and technologies that are environmentally friendly and have no bad impact on the environment, are cost-effective and easily accessible to farmers, resulting in overall food productivity enhancement. Novel advanced techniques are required that integrate ecological and biological procedures to enhance food production and reduce the use of non-renewable resources, which are harmful to the environment and the health of individuals. The earth's magnetic field (MF) is one of the inevitable environmental factors affecting plant growth and yield. Because the MF technique is environmentally friendly, produces no waste, requires no power supply, and does not emit harmful radiation, it can be used for agricultural sustainability.

A New Magnetic Sensor Concept for Nondestructive Evaluation of Deteriorated Prestressing Strand

This article describes proof-of-concept testing of a sensor based on magnetic field detection to estimate the remaining effective cross-sectional area in corroded prestressing strands inside prestressed concrete beams. The primary corrosion mode is rusting of the strand. The magnetic properties of rust are vastly different from those of steel, thus making a magnetic sensor theoretically feasible. An electromagnet system with Hall sensors has been designed. The electromagnet induces a magnetic field in the specimen by magnetizing it from one side, and at a particular distance from the electromagnet's pole face. At near magnetic saturation, for various diameters and distances of up to 2 in from the magnet face, the induced magnetic field is reliably related to the effective cross-section of the steel bar. Experiments with steel rods and prestressing strands of different diameters conducted in a laboratory are presented. Initial results confirm that by using an appropriate electromagnet based on the magnetic-field technique, in-situ detection of remaining effective cross-sectional area is possible. Challenges in making this technique practical are discussed. If the follow-up research confirms the practicality of the proposed magnetic sensor, there is a potential to substantially improve the state-of-the-art in bridge inspection in terms of accuracy and convenience.

Near spherical shell-model structure of the21+state inAr40fromg-factor measurements

The g factor of the ${2}_{1}^{+}$ state in $^{40}\mathrm{Ar}$ has been measured by use of Coulomb excitation in inverse kinematics and the transient magnetic-field technique. The resulting g factor, $g({2}_{1}^{+})=\ensuremath{-}0.015(42)$, is in reasonable agreement with shell-model calculations within the (full $\mathit{sd}){}_{\ensuremath{\pi}}$(full $\mathit{fp}){}_{\ensuremath{\nu}}$ space, without including core excitations. Although highly deformed admixtures in the wave function cannot be completely ruled out, they are small, in contrast to the case of $^{42}\mathrm{Ca}$.

First g-factor measurement using a radioactive 76Kr beam

The g factor of the first 2 1 + state of radioactive 76Kr (T 1/2 = 14:8 h) has been measured using projectile Coulomb excitation in inverse kinematics combined with the transient magnetic-field technique. The 76Kr beam was produced and accelerated in batch mode (re-cyclotron method) at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. The g factor g(76Kr; 21/+) = +0.37(11) was obtained

Physiology of the eyelid motor system.

The eyelid motor system represents an excellent experimental model for the study of reflex and learned motor responses. Eyelid responses can be recorded quantitatively with the search coil in a magnetic-field technique. Stimuli able to evoke reflex blinks (air puffs, flashes of light, tones) can also be controlled quantitatively. Eyelid movements can be classified as spontaneous, passive (such as those following eye saccades), reflex, and acquired with classical conditioning procedures. Information is available regarding the firing activity of brainstem motoneuronal pools (abducens, accessory abducens, and facial motoneurons) involved in these types of eyelid response. In particular, facial motoneurons present different encoding properties for the generation of reflex against learned eyelid responses. In cats, accessory abducens motoneurons are involved only in reflex (but not in learned) blinks. The recent description of the complete organization of premotoneuronal pathways related to eyelid motorics opens new experimental possibilities for the study of this particular motor system.

Single-crystal silicon microblocks produced by a selective recrystallization technique

A previously reported ac magnetic-field technique has here been applied to selective recrystallization on quartz substrates of polysilicon thin films which had been patterned into specific microblock designs. With the recrystallization it has been possible to produce single-crystal silicon microblocks of a maximum size of approximately 60×40×2 μm,3 large enough for the fabrication of high-performance thin-film transistors. Microblocks used in the experiments were of two types: ‘‘network’’ rectangles, connected on the wafer two dimensionally with polysilicon paths, and ‘‘isolated’’ rectangles adjacent to the network rectangles. The surface morphology of the recrystallized silicon films was observed with scanning electron microscopy. While no grain boundaries were found on the surfaces of the recrystallized network rectangles, many grain boundaries were observed to remain on the recrystallized isolated rectangles. X-ray diffractions for the recrystallized network rectangles were measured with a microfocused x-ray beam, and the recrystallized network rectangles were confirmed to be single-crystal silicon microblocks of good crystal quality. It had been expected that network rectangles would be more greatly heated, as compared to isolated rectangles, by the eddy currents induced by the ac magnetic fields, and the observed higher quality of network-rectangle recrystallization has verified that anticipated eddy-current contribution.

G factors for yrast states in isotopic doublets 156,158Gd and 166,168Er.

The gyromagnetic factors of yrast states in {sup 156,158}Gd and {sup 166,168}Er, belonging to the ground-state rotational band, have been measured with the transient magnetic-field technique. Levels of interest were populated in charge exchange induced by a {sup 58}Ni beam. Mixed enriched isotope targets were employed in order to avoid systematic errors when comparing the results for the different isotopes. {sup 158}Gd and {sup 168}Er were used as internal calibration. In both {sup 156}Gd and {sup 166}Er significantly smaller reduction of the {ital g} factor with increasing spin has been found than previously reported, in agreement with the predictions of cranked-shell-model and cranked Hartree-Fock-Bogouliubov calculations.

Phonon Avalanche in Ce-Doped Lanthanum Magnesium Double Nitrate. Measurement of the Phonon Lifetime and of the Acoustic Spectrum

We have investigated the phonon avalanche in Ce-doped lanthanum magnesium double nitrate using pulsed microwave and pulsed magnetic-field techniques. In these experiments we have been able to determine the lifetime of the avalanche phonons and to obtain some evidence for coherence in the spin-phonon interaction.