Engineering topics

Chang, Liang

Publications and source records attributed to Chang, Liang.

3 records

DOE OSTI2023

Superstructured NiMoO 4 @CoMoO 4 core-shell nanofibers for supercapacitors with ultrahigh areal capacitance

High areal capacitance for a practical supercapacitor electrode requires both large mass loading and high utilization efficiency of electroactive materials, which presents a great challenge. Herein, we demonstrated the unprecedented synthesis of superstructured NiMoO 4 @CoMoO 4 core-shell nanofiber arrays (NFAs) on a Mo-transition-layer-modified nickel foam (NF) current collector as a new material, achieving the synergistic combination of highly conductive CoMoO 4 and electrochemical active NiMoO 4 . Moreover, this superstructured material exhibited a large gravimetric capacitance of 1,282.2 F/g in 2 M KOH with a mass loading of 7.8 mg/cm 2 , leading to an ultrahigh areal capacitance of 10.0 F/cm 2 that is larger than any reported values of CoMoO 4 and NiMoO 4 electrodes. In conclusion, this work provides a strategic insight for rational design of electrodes with high areal capacitances for supercapacitors.

42 ENGINEERING↗

DOE OSTI2018

Correlation between the Dzyaloshinskii-Moriya interaction and spin-mixing conductance at an antiferromagnet/ferromagnet interface

The rich interaction phenomena at antiferromagnet (AFM)/ferromagnet (FM) interfaces are key ingredients in AFM spintronics, where many underlying mechanisms remain unclear. Here in this paper we report on a correlation observed between the interfacial Dzyaloshinskii-Moriya interaction (DMI) D S and effective spin-mixing conductance g$↑↓\atop{eff}$ at the IrMn/CoFeB interface. Both DS and g$↑↓\atop{eff}$ are quantitatively determined with Brillouin light-scattering measurements, and increase with IrMn thickness in the range of 2.5 ~ 7.5 nm. Such correlation likely originates from the AFM-states-mediated spin-flip transitions in the FM, which promote both the interfacial DMI and spin pumping effect. Our findings provide deeper insight into the AFM-FM interfacial coupling for future spintronic design.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

NASA NTRS1992

CFD applications in pump flows

The objective of the proposed paper is to develop a computational procedure that solves incompressible Navier-Stokes equations for pump flows. The solution method is based on the pseudo-compressibility approach and uses an implicit-upwind differencing scheme together with the Gauss-Seidel line relaxation method. The equations are solved in steadily rotating reference frames and the centrifugal force and the Coriolis force are added to the equation of motion. As a benchmark problem, the flow through the Rocketdyne inducer is numerically simulated. A coarse grid solution is obtained with a single zone by using an algebraic turbulence model. In multi-zone fine grid computation, a one-equation Baldwin-Barth turbulence model is utilized. Numerical results are compared with experimental measurements and a good agreement is found between the two. The resulting computer code is then applied to the flow analysis inside a two-stage fuel pump impeller operating at 80 percent, 100 percent, and 120 percent of design flow.

Kiris, Cetin↗