Xi'an Jiaotong University

About: Xi'an Jiaotong University is a education organization based out in Xi'an, China. It is known for research contribution in the topics: Heat transfer & Dielectric. The organization has 85440 authors who have published 99682 publications receiving 1579683 citations. The organization is also known as: '''Xi'an Jiaotong University''' & Xi'an Jiao Tong University.

Flexible Capacitive Pressure Sensor Enhanced by Tilted Micropillar Arrays

Abstract: Sensitivity of the sensor is of great importance in practical applications of wearable electronics or smart robotics. In the present study, a capacitive sensor enhanced by a tilted micropillar array-structured dielectric layer is developed. Because the tilted micropillars undergo bending deformation rather than compression deformation, the distance between the electrodes is easier to change, even discarding the contribution of the air gap at the interface of the structured dielectric layer and the electrode, thus resulting in high pressure sensitivity (0.42 kPa-1) and very small detection limit (1 Pa). In addition, eliminating the presence of uncertain air gap, the dielectric layer is strongly bonded with the electrode, which makes the structure robust and endows the sensor with high stability and reliable capacitance response. These characteristics allow the device to remain in normal use without the need for repair or replacement despite mechanical damage. Moreover, the proposed sensor can be tailored to any size and shape, which is further demonstrated in wearable application. This work provides a new strategy for sensors that are required to be sensitive and reliable in actual applications.

A Transforming Metal Nanocomposite with Large Elastic Strain, Low Modulus, and High Strength

Abstract: Freestanding nanowires have ultrahigh elastic strain limits (4 to 7%) and yield strengths, but exploiting their intrinsic mechanical properties in bulk composites has proven to be difficult. We exploited the intrinsic mechanical properties of nanowires in a phase-transforming matrix based on the concept of elastic and transformation strain matching. By engineering the microstructure and residual stress to couple the true elasticity of Nb nanowires with the pseudoelasticity of a NiTi shape-memory alloy, we developed an in situ composite that possesses a large quasi-linear elastic strain of over 6%, a low Young's modulus of ~28 gigapascals, and a high yield strength of ~1.65 gigapascals. Our elastic strain-matching approach allows the exceptional mechanical properties of nanowires to be exploited in bulk materials.

Dielectric elastomer actuators under equal-biaxial forces, uniaxial forces, and uniaxial constraint of stiff fibers

Abstract: A membrane of a dielectric elastomer deforms when a voltage is applied through its thickness. The achievable voltage-induced deformation is strongly affected by how mechanical loads are applied. Large voltage-induced deformation has been demonstrated for a membrane under equal-biaxial forces, but only small voltage-induced deformation has been observed for a membrane under a uniaxial force. This difference is interpreted here theoretically. The theory also predicts that, when the deformation of a membrane is constrained in one direction, a voltage applied through the thickness of the membrane can cause it to deform substantially in the other direction. Experiments are performed on membranes under equal-biaxial forces and uniaxial forces, as well as on fiber-constrained membranes of two types: a dielectric elastomer membrane with carbon fibers on both faces, and two dielectric elastomer membranes sandwiching nylon fibers. The experimental observations are compared with the theory.

Measurement of the Electron Antineutrino Oscillation with 1958 Days of Operation at Daya Bay

Abstract: We report a measurement of electron antineutrino oscillation from the Daya Bay Reactor Neutrino Experiment with nearly 4 million reactor ν[over ¯]_{e} inverse β decay candidates observed over 1958 days of data collection. The installation of a flash analog-to-digital converter readout system and a special calibration campaign using different source enclosures reduce uncertainties in the absolute energy calibration to less than 0.5% for visible energies larger than 2 MeV. The uncertainty in the cosmogenic ^{9}Li and ^{8}He background is reduced from 45% to 30% in the near detectors. A detailed investigation of the spent nuclear fuel history improves its uncertainty from 100% to 30%. Analysis of the relative ν[over ¯]_{e} rates and energy spectra among detectors yields sin^{2}2θ_{13}=0.0856±0.0029 and Δm_{32}^{2}=(2.471_{-0.070}^{+0.068})×10^{-3} eV^{2} assuming the normal hierarchy, and Δm_{32}^{2}=-(2.575_{-0.070}^{+0.068})×10^{-3} eV^{2} assuming the inverted hierarchy.