Engineering topics

Feng, Yuxin

Publications and source records attributed to Feng, Yuxin.

3 records

DOE OSTI2014

Three dimensional transducer

A testing instrument for mechanical testing at nano or micron scale includes a transducer body, and a coupling shaft coupled with a probe tip. A transducer body houses a capacitor. The capacitor includes first and second counter electrodes and a center electrode assembly interposed therebetween. The center electrode assembly is movable with the coupling shaft relative to the first and second counter electrodes, for instance in one or more of dimensions including laterally and normally. The center electrode assembly includes a center plate coupled with the coupling shaft and one or more springs extending from the center plate. Upper and lower plates are coupled with the center plate and cover the center plate and the one or more springs. A shaft support assembly includes one or more support elements coupled along the coupling shaft. The shaft support assembly provides lateral support to the coupling shaft.

47 OTHER INSTRUMENTATION↗

NASA NTRS2002

How Do The Relativistic Effects Effect the Appearance of a Clothed Black Hole?

For an accretion disk around a black hole, the strong relativistic effects affect every aspect of the radiation from the disk, including the spectrum, the light-curve, and the image. If the disk is in high inclination angle (nearly edge-on), the image will be greatly distorted; the farther side of the disk will appear to bend toward the observer, photons from the other side of the disk can reach the observer (if they are not blocked by the disk) to form a ghost image. This work differs mainly from previous work by taking into account the temperature distribution of a standard thin disk model and investigating the expected images from different viewing angles and in different energy bands. The edge-blocking effect is also considered. Direct images of black hole systems may be obtained with future X-ray missions like MAXIM pathfinder.

Zhang, Xiaoling↗

NASA NTRS2002

Studying the Warm Layer and the Hardening Factor in Cygnus X-1

As the first dynamically determined black hole X-ray binary system, Cygnus X-1 has been studied extensively. However, its broadband spectrum observed with BeppoSax is still not well understood. Besides the soft excess described by the multi-color disk model (MCD), the power-law hard component and a broad excess feature above 10 keV (a disk reflection component), there is also an additional soft component around 1 keV, whose origin is not known currently. Here we propose that the additional soft component is due to the thermal Comptonization between the soft disk photons and a warm plasma cloud just above the disk, i.e., a warm layer. We use the Monte-Carlo technique to simulate this Compton scattering process and build a table model based on our simulation results. With this table model, we study the disk structure and estimate the hardening factor to the MCD component in Cygnus X-1.

Yao, Yangsen↗