2,653 research outputs found
Moir\'{e} Flat Bands of Twisted Few-layer Graphite
We report that the twisted few layer graphite (tFL-graphite) is a new family
of moir\'{e} heterostructures (MHSs), which has richer and highly tunable
moir\'{e} flat band structures entirely distinct from all the known MHSs. A
tFL-graphite is composed of two few-layer graphite (Bernal stacked multilayer
graphene), which are stacked on each other with a small twisted angle. The
moir\'{e} band structure of the tFL-graphite strongly depends on the layer
number of its composed two van der Waals layers. Near the magic angle, a
tFL-graphite always has two nearly flat bands coexisting with a few pairs of
narrowed dispersive (parabolic or linear) bands at the Fermi level, thus,
enhances the DOS at . This coexistence property may also enhance the
possible superconductivity as been demonstrated in other multiband
superconductivity systems. Therefore, we expect strong multiband correlation
effects in tFL-graphite. Meanwhile, a proper perpendicular electric field can
induce several isolated nearly flat bands with nonzero valley Chern number in
some simple tFL-graphites, indicating that tFL-graphite is also a novel
topological flat band system.Comment: Submitted version,supplementary materials are adde
Reliable Data Transmission through Private CBRS Networks
We consider the use of a domain proxy assisted private citizen broadband
radio service (CBRS) network and propose a Maximum Transmission Continuity
(MTC) scheme to transmit Internet of Things (IoT) data reliably. MTC
dynamically allocates available CBRS channels to sustain the continuity of data
transmission without violating the channel access requirements. MTC allocates
the granted CBRS channels according to the priority of each user, the instant
channel access status, interference among users, and the fairness. The
simulation results demonstrate the improvement in managing reliable IoT data
transmission in the private CBRS network.Comment: 5 pages, 5 figure
Application of CCG Sensors to a High-Temperature Structure Subjected to Thermo-Mechanical Load
This paper presents a simple methodology to perform a high temperature coupled thermo-mechanical test using ultra-high temperature ceramic material specimens (UHTCs), which are equipped with chemical composition gratings sensors (CCGs). The methodology also considers the presence of coupled loading within the response provided by the CCG sensors. The theoretical strain of the UHTCs specimens calculated with this technique shows a maximum relative error of 2.15% between the analytical and experimental data. To further verify the validity of the results from the tests, a Finite Element (FE) model has been developed to simulate the temperature, stress and strain fields within the UHTC structure equipped with the CCG. The results show that the compressive stress exceeds the material strength at the bonding area, and this originates a failure by fracture of the supporting structure in the hot environment. The results related to the strain fields show that the relative error with the experimental data decrease with an increase of temperature. The relative error is less than 15% when the temperature is higher than 200 °C, and only 6.71% at 695 °C
Measurement of the high-temperature strain of UHTC materials using chemical composition gratings
Probabilistic Reliability Analysis of Carbon/Carbon Composite Nozzle Cones with Uncertain Parameters
A methodology to perform the probabilistic and reliability-based design of a novel carbon/carbon rocket nozzle subjected to operational thermal and mechanical loads is described in this paper. In this methodology, the nozzle is represented by a multiphysics finite element model capable of predicting the temperature and stress fields of the exit cone. The analysis shows that the most likely failure modes of the exit cone are related to compressive stress along the axial and hoop directions, as well as interlaminar shear. The probabilistic models used in this methodology account for the uncertainty of the material properties by using uniform and normal distributions and different variances. The reliability analysis is performed by using surface response methods. A global sensitivity analysis is also carried out using polynomial expansion chaos surface response models. A particular novelty of the analysis is the use of Sobol indices to rank the importance of the single uncertain parameters in the models. The methodology provides a high level of confidence and robustness in determining that the axial thermal conductivity of the carbon/carbon material is the most critical material property to affect the three main failure modes, whereas the coefficient of the thermal expansion and the heat capacity play a very marginal role
Enzymatic Sensor for Sterigmatocystin Detection and Feasibility Investigation of Predicting Aflatoxin B1 Contamination by Indicator
Genome-Wide Association Analyses Highlight the Potential for Different Genetic Mechanisms for Litter Size Among Sheep Breeds
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