87 research outputs found
Continuous-wave and Transient Characteristics of Phosphorene Microwave Transistors
Few-layer phosphorene MOSFETs with 0.3-um-long gate and 15-nm-thick Al2O3
gate insulator was found to exhibit a forward-current cutoff frequency of 2 GHz
and a maximum oscillation frequency of 8 GHz after de-embedding for the
parasitic capacitance associated mainly with the relatively large probe pads.
The gate lag and drain lag of the transistor was found to be on the order of 1
us or less, which is consistent with the lack of hysteresis, carrier freeze-out
or persistent photoconductivity in DC characteristics. These results confirm
that the phosphorene MOSFET can be a viable microwave transistor for both
small-signal and large-signal applications.Comment: Accepted for oral presentation at IMS 201
Trade shock, refugee, and the rise of right-wing populism : evidence from European Parliament elections
Recent years have witnessed the rising support for right-wing populism in European politics. We rely on the outcomes of the 2014 European Parliament elections to empirically examine the economic and cultural mechanisms that fuel this trend. Using import competition to measure economic shocks and regional-level refugee shocks, we find that regions exposed to more intense trade shocks are more likely to vote for right-wing parties. We further show the increasing support for economically far-right parties is mainly caused by trade shocks, and the electoral support for culturally far-right parties stems mainly from refugee shocks
THE HYDRAULICS OF NATURE-LIKE FISHWAYS
Nature-like fishway arrangements are commonly used because these structures imitate the characteristics of natural rivers and effectively allow fish to migrate past river sections blocked by hydraulic structures. In this paper, physical models were analyzed, and the velocity distributions of two different fishway structures (Types I and II) were compared. Results showed that the maximum mainstream velocity of the Type I structure was 5.3% lower than that of the Type II structure. However, the average mainstream velocity of the Type I structure was 21.1% greater than that of the Type II structure. The total per-cycle length of the mainstream path in the Type II structure was 2.1 times greater than that of the Type I structure, which indicated that the length of the mainstream path was somewhat proportional to the average velocity of the mainstream. When the flow rate was kept constant, increases in the velocity of the main flow associated with changes in the internal structure of the fishway decreased the average velocity of the main flow, while decreases in the total length of the flow path led to increases in the average velocity of the main flow. Due to frictional head loss along the fishway and local head loss, as well as the overlaps between these factors, the overall flow rate gradually decreased every cycle, despite periodic fluctuations
Emergent criticality in fully frustrated quantum magnets
Phase transitions in condensed matter are often linked to exotic emergent
properties. We study the fully frustrated bilayer Heisenberg antiferromagnet to
demonstrate that an applied magnetic field creates a novel emergent
criticality. The quantum phase diagram contains four states, the DS (singlets
on every interlayer dimer bond), DTAF (all triplets with antiferromagnetic
order), TC (a singlet-triplet checkerboard) and FM (saturated ferromagnet). The
thermal phase diagram is dominated by a wall of discontinuities extending from
the zero-field DTAF-DS transition to a quantum critical endpoint where the
field drives the DTAF and TC into the FM. This first-order wall is terminated
at finite temperatures by a line of critical points, where the
Berezinskii-Kosterlitz-Thouless (BKT) transition of the DTAF and the thermal
Ising transition of the TC also terminate. We demonstrate by quantum Monte
Carlo simulations that the BKT transition does not change the Ising nature of
the DTAF-DS critical line. By contrast, the combination of symmetries merging
on the multicritical DTAF-TC line leads to a 4-state Potts universality not
contained in the microscopic Hamiltonian, which we associate with the
Ashkin-Teller model. Our results represent a systematic step in understanding
emergent phenomena in quantum magnetic materials including the
``Shastry-Sutherland compound'' SrCu(BO).Comment: 10+8 pages, 5+7 figure
Non-invasive color imaging through scattering medium under broadband illumination
Due to the complex of mixed spectral point spread function within memory
effect range, it is unreliable and slow to use speckle correlation technology
for non-invasive imaging through scattering medium under broadband
illumination. The contrast of the speckles will drastically drop as the light
source's spectrum width increases. Here, we propose a method for producing the
optical transfer function with several speckle frames within memory effect
range to image under broadband illumination. The method can be applied to image
amplitude and color objects under white LED illumination. Compared to other
approaches of imaging under broadband illumination, such as deep learning and
modified phase retrieval, our method can provide more stable results with
faster convergence speed, which can be applied in high speed scattering imaging
under natural light illumination
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