Simultaneous localization of photons and phonons in defect-free dodecagonal phoxonic quasicrystals

2018 ◽  
Vol 32 (07) ◽  
pp. 1850096
Author(s):  
Bihang Xu ◽  
Zhong Wang ◽  
Yixiang Tan ◽  
Tianbao Yu
Keyword(s):  
Elastic Waves ◽  
Rotational Symmetry ◽  
Elastic Field ◽  
Band Gaps ◽  
High Symmetry ◽  
Localized Modes ◽  
Wide Range ◽  
Quasiperiodic Structures ◽  
Phononic Band Gaps ◽  
Very High

In dodecagonal phoxonic quasicrytals (PhXQCs) with a very high rotational symmetry, we demonstrate numerically large phoxonic band gaps (PhXBGs, the coexistence of photonic and phononic band gaps). By computing the existence and dependence of PhXBGs on the choice of radius of holes, we find that PhXQCs can possess simultaneous photonic and phononic band gaps over a rather wide range of geometric parameters. Furthermore, localized modes of THz photons and tens of MHz phonons may exist inside and outside band gaps in defect-free PhXQCs. The electromagnetic and elastic field can be confined simultaneously around the quasicrytals center and decay in a length scale of several basic cells. As a kind of quasiperiodic structures, 12-fold PhXQCs provide a good candidate for simultaneously tailoring electromagnetic and elastic waves. Moreover, these structures exhibit some interesting characteristics due to the very high symmetry.

Phononic Band Gaps in Al2O3/Epoxy Composite

2018 ◽  
Vol 912 ◽  
pp. 112-117 ◽  
Author(s):  
Edson Jansen Pedrosa Miranda Jr. ◽  
J.M.C. dos Santos
Keyword(s):  
Cross Section ◽  
Transverse Vibration ◽  
Elastic Waves ◽  
Epoxy Composite ◽  
Phononic Crystal ◽  
Band Gaps ◽  
Square Lattice ◽  
Plane Wave Expansion ◽  
Phononic Band Gaps ◽  
Angle Of Rotation

In this study, we have investigated the band structure of elastic waves propagating in a phononic crystal, consisting of an epoxy matrix reinforced by Al2O3 inclusions in a square and hexagonal lattices. We also studied the influence of the inclusion geometry cross section – circular, hollow circular, square and rotated square with a 45° angle of rotation with respect to the x, y axes. The plane wave expansion (PWE) method is used to solve the wave equation considering the wave propagation in the xy plane (longitudinal-transverse vibration, XY mode, and transverse vibration, Z mode). The complete band gaps between the XY and Z modes are observed to circular, square and rotated square cross section inclusion and the best performance is for rotated square cross section inclusion in a square lattice. We suggest that the Al2O3/epoxy composite is feasible for vibrations management.

TEM study of boron additions to cobalt aluminide

1988 ◽  
Vol 46 ◽  
pp. 546-547
Author(s):  
Gerald B. Feldewerth
Keyword(s):  
High Temperature ◽  
Turbine Engines ◽  
Major Drawback ◽  
University Of Missouri ◽  
Specific Strength ◽  
Aerospace Applications ◽  
Wide Range ◽  
Ordered Alloys ◽  
The University ◽  
Very High

In recent years an increasing emphasis has been placed on the study of high temperature intermetallic compounds for possible aerospace applications. One group of interest is the B2 aiuminides. This group of intermetaliics has a very high melting temperature, good high temperature, and excellent specific strength. These qualities make it a candidate for applications such as turbine engines. The B2 aiuminides exist over a wide range of compositions and also have a large solubility for third element substitutional additions, which may allow alloying additions to overcome their major drawback, their brittle nature.One B2 aluminide currently being studied is cobalt aluminide. Optical microscopy of CoAl alloys produced at the University of Missouri-Rolla showed a dramatic decrease in the grain size which affects the yield strength and flow stress of long range ordered alloys, and a change in the grain shape with the addition of 0.5 % boron.

Features of the Christian values ​​system

2004 ◽  
pp. 21-29
Author(s):  
G.V. Pyrog
Keyword(s):  
Public Opinion ◽  
Religious Beliefs ◽  
Religious Values ◽  
Direct Influence ◽  
Moral Norms ◽  
Value System ◽  
Christian Religion ◽  
Mass Consciousness ◽  
Wide Range ◽  
Very High

In domestic scientific and public opinion, interest in religion as a new worldview paradigm is very high. Today's attention to the Christian religion in our society is connected, in our opinion, with the specificity of its value system, which distinguishes it from other forms of consciousness: the idea of ​​God, the absolute, the eternity of moral norms. That is why its historical forms do not receive accurate characteristics and do not matter in the mass consciousness. Modern religious beliefs do not always arise as a result of the direct influence of church preaching. The emerging religious values ​​are absorbed in a wide range of philosophical, artistic, ethical ideas, acting as a compensation for what is generally defined as spirituality. At the same time, the appeal to Christian values ​​became very popular.

DURCOMET 100

Alloy Digest ◽  
1993 ◽  
Vol 42 (2) ◽  
Keyword(s):  
Fracture Toughness ◽  
Wear Resistance ◽  
Corrosion Resistance ◽  
Mechanical Strength ◽  
Heat Treating ◽  
Corrosion And Wear ◽  
Annealed Condition ◽  
Excellent Corrosion Resistance ◽  
Wide Range ◽  
Very High

Abstract Durcomet 100 is an improved version of Alloy CD-4 MCu with better corrosion and wear resistance. The alloy is used in the annealed condition and possesses excellent corrosion resistance over a wide range of corrosion environments. Mechanical strength is also very high. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as heat treating and joining. Filing Code: SS-540. Producer or source: Duriron Company Inc.

Influencia de las condiciones de secado solar en la coloración de plantas medicinales

2019 ◽  
pp. 28-34
Author(s):  
Margarita Castillo-Téllez ◽  
Beatriz Castillo-Téllez ◽  
Juan Carlos Ovando-Sierra ◽  
Luz María Hernández-Cruz
Keyword(s):  
Medicinal Plants ◽  
Forced Convection ◽  
Rural Areas ◽  
Color Change ◽  
Drying Process ◽  
Scientific Medicine ◽  
Drying Time ◽  
Bacterial Proliferation ◽  
Wide Range ◽  
Very High

For millennia, humans have used hundreds of medicinal plants to treat diseases. Currently, many species with important characteristics are known to alleviate a wide range of health problems, mainly in rural areas, where the use of these resources is very high, even replacing scientific medicine almost completely. This paper presents the dehydration of medicinal plants that are grown in the State of Campeche through direct and indirect solar technologies in order to evaluate the influence of air flow and temperature on the color of the final product through the L* a* scale. b*, analyzing the activity of water and humidity during the drying process. The experimental results showed that the direct solar dryer with forced convection presents a little significant color change in a drying time of 400 min on average, guaranteeing the null bacterial proliferation and reaching a final humidity between 9 % and 11 %.

scholarly journals Separate Universe calibration of the dependence of halo bias on cosmic web anisotropy

2020 ◽  
Vol 499 (3) ◽  
pp. 4418-4431 ◽  
Author(s):  
Sujatha Ramakrishnan ◽  
Aseem Paranjape
Keyword(s):  
Dark Matter ◽  
High Precision ◽  
Gaussian Distribution ◽  
Initial Perturbation ◽  
Analytical Framework ◽  
Web Environment ◽  
Wide Range ◽  
Galaxy Assembly ◽  
Very High ◽  
Good Agreement

ABSTRACT We use the Separate Universe technique to calibrate the dependence of linear and quadratic halo bias b1 and b2 on the local cosmic web environment of dark matter haloes. We do this by measuring the response of halo abundances at fixed mass and cosmic web tidal anisotropy α to an infinite wavelength initial perturbation. We augment our measurements with an analytical framework developed in earlier work that exploits the near-lognormal shape of the distribution of α and results in very high precision calibrations. We present convenient fitting functions for the dependence of b1 and b2 on α over a wide range of halo mass for redshifts 0 ≤ z ≤ 1. Our calibration of b2(α) is the first demonstration to date of the dependence of non-linear bias on the local web environment. Motivated by previous results that showed that α is the primary indicator of halo assembly bias for a number of halo properties beyond halo mass, we then extend our analytical framework to accommodate the dependence of b1 and b2 on any such secondary property that has, or can be monotonically transformed to have, a Gaussian distribution. We demonstrate this technique for the specific case of halo concentration, finding good agreement with previous results. Our calibrations will be useful for a variety of halo model analyses focusing on galaxy assembly bias, as well as analytical forecasts of the potential for using α as a segregating variable in multitracer analyses.

scholarly journals The Band-Gap Studies of Short-Period CdO/MgO Superlattices

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Ewa Przeździecka ◽  
P. Strąk ◽  
A. Wierzbicka ◽  
A. Adhikari ◽  
A. Lysak ◽  
...  
Keyword(s):  
Band Gap ◽  
Layer Thickness ◽  
Energy Gap ◽  
Band Gaps ◽  
Short Period ◽  
Wide Range ◽  
Salt Structure ◽  
Short Period Superlattices ◽  
Direct Band ◽  
Sublayer Thickness

AbstractTrends in the behavior of band gaps in short-period superlattices (SLs) composed of CdO and MgO layers were analyzed experimentally and theoretically for several thicknesses of CdO sublayers. The optical properties of the SLs were investigated by means of transmittance measurements at room temperature in the wavelength range 200–700 nm. The direct band gap of {CdO/MgO} SLs were tuned from 2.6 to 6 eV by varying the thickness of CdO from 1 to 12 monolayers while maintaining the same MgO layer thickness of 4 monolayers. Obtained values of direct and indirect band gaps are higher than those theoretically calculated by an ab initio method, but follow the same trend. X-ray measurements confirmed the presence of a rock salt structure in the SLs. Two oriented structures (111 and 100) grown on c- and r-oriented sapphire substrates were obtained. The measured lattice parameters increase with CdO layer thickness, and the experimental data are in agreement with the calculated results. This new kind of SL structure may be suitable for use in visible, UV and deep UV optoelectronics, especially because the energy gap can be precisely controlled over a wide range by modulating the sublayer thickness in the superlattices.

scholarly journals Modelling the atmosphere of lava planet K2-141b: implications for low- and high-resolution spectroscopy

2020 ◽  
Vol 499 (4) ◽  
pp. 4605-4612
Author(s):  
T Giang Nguyen ◽  
Nicolas B Cowan ◽  
Agnibha Banerjee ◽  
John E Moores
Keyword(s):  
Steady State ◽  
Ocean Circulation ◽  
Scale Height ◽  
High Resolution Spectroscopy ◽  
Return Flow ◽  
High Dispersion ◽  
Magma Ocean ◽  
Steady State Flow ◽  
Wide Range ◽  
Very High

ABSTRACT Transit searches have uncovered Earth-size planets orbiting so close to their host star that their surface should be molten, so-called lava planets. We present idealized simulations of the atmosphere of lava planet K2-141b and calculate the return flow of material via circulation in the magma ocean. We then compare how pure Na, SiO, or SiO2 atmospheres would impact future observations. The more volatile Na atmosphere is thickest followed by SiO and SiO2, as expected. Despite its low vapour pressure, we find that a SiO2 atmosphere is easier to observe via transit spectroscopy due to its greater scale height near the day–night terminator and the planetary radial velocity and acceleration are very high, facilitating high dispersion spectroscopy. The special geometry that arises from very small orbits allows for a wide range of limb observations for K2-141b. After determining the magma ocean depth, we infer that the ocean circulation required for SiO steady-state flow is only 10−4 m s−1, while the equivalent return flow for Na is several orders of magnitude greater. This suggests that a steady-state Na atmosphere cannot be sustained and that the surface will evolve over time.

Improvement of the Detection Sensitivity of Edxrf Trace Element Analysis by Means of Efficient X-Ray Focusing Based on Strongly Curved Hopg Crystals

1995 ◽  
Vol 39 ◽  
pp. 109-117
Author(s):  
Burkhard Beckhoff ◽  
Birgit Kanngießer
Keyword(s):  
High Intensity ◽  
Focal Plane ◽  
Bragg Reflection ◽  
Pyrolytic Graphite ◽  
Trace Element Analysis ◽  
Detection Sensitivity ◽  
Element Analysis ◽  
X Ray ◽  
Wide Range ◽  
Very High

X-ray focusing based on Bragg reflection at curved crystals allows collection of a large solid angle of incident radiation, monochromatization of this radiation, and condensation of the beam reflected at the crystal into a small spatial cross-section in a pre-selected focal plane. Thus, for the Bragg reflected radiation, one can achieve higher intensities than for the radiation passing directly to the same small area in the focal plane. In that case one can profit considerably from X-ray focusing in an EDXRF arrangement. The 00 2 reflection at Highly Oriented Pyrolytic Graphite (HOPG) crystals offers a very high intensity of the Bragg reflected beam for a wide range of photon energies. Furthermore, curvature radii smaller than 10 mm can be achieved for HOPG crystals ensuring efficient X-ray focusing in EDXRF applications. For the trace analysis of very small amounts of specimen material deposited on small areas of thin-filter backings, HOPG based X-ray focusing may be used to achieve a very high intensity of monochromatic excitation radiation.

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