Improvement of Pulse Voltage Generated by Wiegand Sensor Through Magnetic-Flux Guidance.

Magnetization reversal in a Wiegand wire induces a pulse voltage in the pickup coil around the wire, called the Wiegand pulse. The Wiegand sensor features the Wiegand wire and the pickup coil. The amplitude and width of the Wiegand pulse are independent of the frequency of the magnetic-field change. The pulse is generated by the Wiegand sensor, which facilitates the use of the Wiegand sensor as a power supply for equipment without batteries. In order to meet the power consumption requirements, it is necessary to maximize the energy of the pulse signal from the Wiegand sensor, without changing the external field conditions. The distributions of the magnetic field generated from the applied magnet in air and in the Wiegand wire were simulated before the experiments. Simulation predicted an increase in the magnetic flux density through the center of the Wiegand wire. This study determined that the magnetic flux density through the center of the Wiegand wire, the position of the pickup coil, and the angle between the Wiegand sensor and the magnetic induction line were the main factors that affected the energy of a Wiegand pulse. The relationship between these factors and the energy of the Wiegand pulse were obtained.

Magnetization of Wiegand Wires with Varying Diameters and Analysis of Their Magnetic Structure via Hysteresis Loops.

Wiegand wires are unique ferromagnetic materials that display rapid magnetization reversal and a large Barkhausen jump under an applied field. This stable reversal can be used to induce a periodic pulse voltage in a pickup coil wrapped around the Wiegand wire. To unlock the full potential of Wiegand wires for magnetic sensors and devices, the magnetic structure and magnetization state of the Wiegand wire must be fully elucidated. In this study, hysteresis loops were used to reveal the magnetic structure of Wiegand wires. Wiegand wires of different diameters magnetized under different applied magnetic field strengths were analyzed in detail. Our results show that Wiegand wires 0.06 mm in diameter are composed solely of a hard magnetic core. Wiegand wires above 0.10 mm in diameter have a hard magnetic core, a middle layer, and a soft layer that decreases in thickness but increases in coercivity as the wire diameter decreases. Then, theoretical models were built to predict the magnetic structure of Wiegand wires under an applied field for the first time. The magnetization process of Wiegand wires with different diameters under different applied magnetic fields was also analyzed.

Magnetic Structure of Wiegand Wire Analyzed by First-Order Reversal Curves.

Various coercive force field components in Wiegand wire exhibit a significant magnetization reversal under an applied magnetic field. A fast magnetization reversal is accompanied by a large Barkhausen jump, which induces a pulse voltage in a pickup coil wound around the Wiegand wire which serves as a power source for the devices or sensors. This study aims to elucidate the magnetization reversal in the Wiegand wire by using a first-order reversal curve (FORC) diagram method. The magnetic structure of the Wiegand wire typically comprises three layers: a soft layer, middle layer, and hard layer. In this study, we analyze the coercive and interactive force fields between the adjacent layers. The results demonstrate a high coercivity of the center core and a lower coercivity of the outer layer of the wire.

Magnetic Interactions in Wiegand Wires Evaluated by First-Order Reversal Curves.

Wiegand wires exhibit a unique fast magnetization reversal feature in the soft layer that is accompanied by a large Barkhausen jump, which is also known as the Wiegand effect. However, the magnetic structure and interaction in Wiegand wires cannot be evaluated by conventional magnetization hysteresis curves. We analyzed the magnetic properties of Wiegand wires at various lengths by measuring the first-order reversal curves (FORCs) and by evaluating the FORC diagram from a series of FORCs. In particular, we used a FeCoV Wiegand wire with a magnetic soft outer layer, an intermediate layer, and a hard core. The magnetization of the various layers in the wire could be identified from the FORC diagrams. Furthermore, based on the interaction between multiple layers, the positive and negative polarity of the FORC distribution was clarified.

Magnetic Reversal in Wiegand Wires Evaluated by First-Order Reversal Curves.

The magnetic structure of Wiegand wires cannot be evaluated using conventional magnetization hysteresis curves. We analyzed the magnetization reversal of a Wiegand wire by measuring the first-order reversal curves (FORCs). A FeCoV Wiegand wire with a magnetically soft outer layer and a hard magnetic core was used in this study. The magnetization reversal of the soft and hard regions in the wire was identified in the FORC diagrams. The magnetization reversal of the dominantly irreversible process of the soft layer and the magnetic intermediate region between the soft and hard regions was clarified.

Strawberry Proteome Responses to Controlled Hot and Cold Stress Partly Mimic Post-harvest Storage Temperature Effects on Fruit Quality.

To determine the effect of different temperature on strawberry after harvest, physiological indicator analysis and proteomics analysis were conducted on ripened strawberry ("Sweet Charlie") fruit stored at 4, 23, and 37°C for 10 or 20 days. Results showed that 4°C maintained a better visual quality of strawberry, and the weight loss and firmness remained stable within 3 days. Low temperature negatively affected anthocyanin but positively affected soluble sugars. Though anthocyanin content was higher with increasing temperature, anthocyanin synthesis related proteins were downregulated. Higher indole-acetic acid (IAA) content in seeds and lower abscisic acid (ABA) content were found in berry at 4°C. Antioxidant related proteins were upregulated during storage, showing a significant up-regulation of peroxidase (POD) at 4°C, and ascorbate-glutathione (AsA-GSH) cycle related proteins and heat shock proteins (HSPs) at 37°C. In addition, overexpressed sugar phosphate/phosphate translocator, 1-aminocyclopropane-1-carboxylate oxidase, and aquaporin PIP2-2 had a positive effect in response to low temperature stress for containing higher protopectin content and POD activity.