No abstract

Spin-torque diodes (STDs) offer the possibility of using spin torque to generate rectification voltage with promising applications in microwave detecting, energy harvesting, and neuromorphic computing. Here, we demonstrate a highly sensitive STD with ultralow current density based on a magnetic tunnel junction with perpendicular magnetic anisotropy. At zero magnetic field, a high sensitivity exceeding 3785 V/W is obtained with a low current of −20 μA, corresponding to a current density of ∼105 A/cm2, which is one order lower than the previously reported. When a weak external magnetic field is applied, the sensitivity can be further increased by five times to 20 000 V/W. Furthermore, we construct an artificial neural network with STD neurons to perform recognition of handwritten digits in the Mixed National Institute of Standards and Technology database, where a produced accuracy of up to 94.92% is obtained. Our work provides a route to develop low-power consumption high-sensitivity STDs for Internet of Things applications and neuromorphic computing.

No abstract

The monitoring of acoustic emission (AE) has allowed tracing of the damage in wooden cultural objects exposed to variations in ambient relative humidity (RH). A year-long on-site AE monitoring of the Song Dynasty shipwreck confirmed the usefulness of the technique in tracing climate-induced damage in wood. New coupling material is tested to make it conform to the conservation rules which is non-corrosive to monitoring objects and a reversible operation. As sensitive parameter of wood damage caused by variations RH, the accumulated ringing counting tends to increase with the increase of daily fluctuation of RH (DFRH). In addition, the damage of wooden cultural objects during shrinkage is stronger than that during swelling. The relationship between the probability of AE activity and the daily DFRH is established and it is determined that the daily variation of RH for long-term protection of the Song Dynasty shipwreck should be controlled within 4%, and an early warning will be given if it exceeds 10%.

No abstract

No abstract

No abstract

No abstract