Broadband reflectors with a disordered layered structure: statistical properties of high performing configurations selected via genetic algorithm

Disordered multilayers consisting of alternating layers of two lossless dielectric materials with random thicknesses can behave as good reflectors in wide wavelength ranges except for narrow bands where the transmittance is significative. We use a dedicated genetic algorithm to select different configurations (thickness sequences) of such structures which exhibit very low transmittance in the entire visible wavelength range, showing that broadband disordered reflectors with very high performance can be designed. A statistical analysis of the thickness sequences selected by the genetic algorithm reveals that such sequences are characterized by correlated disorder and that the degree of autocorrelation is a key parameter in determining the reflection performance.

HEADDRESSES AS SYMBOLS OF HIGH SOCIAL STATUS (BASED ON NEAR EASTERN MATERIALS OF THE EARLY METALS PERIOD)

Статья посвящена археологическим находкам металлических деталей головных уборов. Диадемы в виде длинных узких лент появляются на Ближнем Востоке во второй половине IV тыс. до н. э. В III тыс. до н. э. вырабатываются другие типы головных украшений, среди которых простые овальные и ромбовидные налобные бляхи и сложные конструкции с дополнительными деталями. Соответствующие находки рассматриваются как маркеры высокого социального статуса, связанные с процессом формирования элитарных групп в догосударственных и раннегосударственных обществах Месопотамии и Анатолии. The article is focused on the archaeological finds of headdress details made of metals. The diadems in the shape of long narrow bands appeared in the Near East in the second half of the 4th millennium BC. In the 3rd millennium BC other types of head ornaments were introduced, among them oval and rhomboidal frontlets and elaborate constructions with additional details. The corresponding finds are considered as markers of high social position related with the process of formation of elite groups in pre-state and early state societies in Mesopotamia and Anatolia.

Identifying the microtearing modes in the pedestal of DIII-D H-modes using gyrokinetic simulations

Recent evidence points toward the microtearing mode (MTM) as an important fluctuation in the H-mode pedestal for anomalous electron heat transport. A study of the instabilities in the pedestal region carried out using gyrokinetic simulations to model an ELMy H-mode DIII-D discharge (USN configuration, 1.4 MA plasma current, and 3 MW heating power) is presented. The simulations produce MTMs, identified by predominantly electromagnetic heat flux, small particle flux, and a substantial degree of tearing parity. The magnetic spectrogram from Mirnov coils exhibits three distinct frequency bands---two narrow bands at lower frequency ($\sim$35-55 kHz and $\sim$70-105 kHz) and a broader band at higher frequency ($\sim$300-500 kHz). Global linear GENE simulations produce MTMs that are centered at the peak of the $\omega_*$ profile and correspond closely with the bands in the spectrogram. The three distinctive frequency bands can be understood from the basic physical mechanisms underlying the instabilities. For example (i) instability of certain toroidal mode numbers (n) is controlled by the alignment of their rational surfaces with the peak in the $\omega^*$ profile, and (ii) MTM instabilities in the lower n bands are the conventional collisional slab MTM, whereas the higher n band depends on curvature drive. While many features of the modes can be captured with the local approximation, a global treatment is necessary to quantitatively reproduce the detailed band gaps of the low-n fluctuations. Notably, the transport signatures of the MTM are consistent with careful edge modeling by SOLPS.

Compact Exposimeter Device for the Characterization and Recording of Electromagnetic Fields from 78 MHz to 6 GHz with Several Narrow Bands (300 kHz)

A novel compact device with spectrum analyzer characteristics has been designed, which allows the measuring of the maximum power received in multiple narrow frequency bands of 300 kHz, recording the entire spectrum from 78 MHz to 6 GHz; the device is capable of measuring the entire communications spectrum and detecting multiple sources of electromagnetic fields using the same communications band. The proposed device permits the evaluation of the cross-talk effect that, in conventional exposimeters, generates a mistake estimation of electromagnetic fields. The device was calibrated in an anechoic chamber for far-fields and was validated against a portable spectrum analyzer in a residential area. A strong correlation between the two devices with a confidence higher than 95% was obtained; indicating that the device could be considered as an important tool for electromagnetic field studies.

The Mechanism of Destruction Under the Influence of Shock Waves

The spectra of the plasma emitted from the studied samples consist of several dozens of narrow bands superimposed on each other. Tables of spectral lines were used to interpret the spectra. It turned out that the largest number of bands corresponds to the radiation of positively charged ions and atoms of elements that make up the crystal lattices of minerals that make up the studied rocks. Thus, the spectra of the plasma emitted from quartz corresponded to the radiation of atoms and positively charged silicon ions, the charge of which varied from 1 to 4, as well as atoms and positively charged oxygen ions, the charge of which varied from 1 to 3. Positively charged ions and atoms of Si, O, K, Ca, Al and Na, which are part of the crystal lattices of quartz and feldspar, flew out of granites. Positively charged ions and Ca, C and O atoms flew out of the calcite.

A Compact Dual Notch Frequency Reconfigurable Antenna for WIMAX,DSRC, RADAR and Ku band Communication Applications

A frequency reconfigurable ultra-wide band antenna with dual notch bands is proposed in this paper. PIN diodes are located on ultra-wide band monopole antenna and are investigated for frequency reconfigurable characteristic of the proposed antenna. Multi-bands and narrow bands have been achieved by different combinations. Proposed antenna is fabricated on FR-4 substrate of dimensions 37 x 40 x 0.8mm3. For the successful combinations, antenna performance parameters like S11 characteristics, surface current distribution, peak gain, radiation efficiency and 2D radiation patterns are analyzed and illustrated in the paper. Peak gain of 4.83dB is obtained in operating band for D1, D2= 0, 1 combination. Radiation efficiency is not less than 70% in the entire operating bands. Results are analyzed experimentally for validating proposed antenna. Simulation based results and measured results are in good agreement.

Comparison of anatomical features in the three Syzygium species

This study was conducted to provide foundational anatomical information of three infrequently used wood species growing in tropical areas. Three species of the genus Syzygium, namely the clove tree, kupa, and spicate eugenia, were selected. The representative anatomical features of these species were classified using the International Association of Wood Anatomists (IAWA) anatomical feature list. The representative anatomical features of the clove tree included the distribution of small vessels with tangential diameters of approximately 60 µm in cross-surface, a dense spacing of vessels, the axial parenchyma in narrow bands or lines up to three cells wide, and the body ray cells procumbent with over four rows of upright and/or square marginal cells. The kupa showed axial parenchyma confluent and the body ray cells were procumbent with over four rows of upright and/or square marginal cells. In the spicate eugenia, the axial parenchyma was diffused in aggregate with exclusively uniseriate rays and the body ray cells were procumbent with one row of upright and/or square marginal cells. These three species were easily identified by optical microscopy via the anatomical features of the woods.