Artykuły w czasopismach: „Packard Band”

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Holland, Mark R., Stephen H. Lewis, Christopher S. Hall, Ann E. Finch-Johnston, Scott M. Handley, Kirk D. Wallace, Alwyn P. D'sa, David M. Prater, Julio E. Perez i James G. Miller. "Effects of Tissue Anisotropy on the Spectral Characteristics of Ultrasonic Backscatter Measured with a Clinical Imaging System". Ultrasonic Imaging 20, nr 3 (lipiec 1998): 178–90. http://dx.doi.org/10.1177/016173469802000303.

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In this paper, we report the effects of inherent tissue anisotropy on the spectral properties of backscattered ultrasound when measured with a commercially-available imaging system. We insonified five specimens of bovine tendon immersed in a water tank and rotated in 10° increments while being imaged with a Hewlett-Packard Sonos 1500 system. The backscattered RF signals corresponding to each angle of insonification were digitized and the spectral characteristics of the backscattered ultrasound were determined. The mean anisotropy, defined as the average difference between values at perpendicular and parallel insonification, for band-limited estimates of backscattered power, centroid frequency, upper-band to lower-band power ratio, and upper-band to total-band power ratio were found to be 24.6 ± 1.1 dB, 142 ± 27 kHz, 32 ± 13%, and 22 ± 5%, respectively (mean ± SE). The magnitude of each of these backscatter spectral parameters was larger at perpendicular insonification compared with the corresponding values at parallel insonification, consistent with previous measurements of the inherent anisotropy of ultrasonic attenuation and backscatter in tissue.

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Seman, Michael. "What If Hewlett and Packard Had Started a Band Instead? An Examination of a Music Scene as Economic Cluster". Artivate 4, nr 2 (2015): 33–49. http://dx.doi.org/10.1353/artv.2015.0005.

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Chéron, Jérôme, Michel Campovecchio, Denis Barataud, Tibault Reveyrand, Michel Stanislawiak, Philippe Eudeline i Didier Floriot. "Wideband harmonically matched packaged GaN HEMTs with high PAE performances at S-band frequencies". International Journal of Microwave and Wireless Technologies 5, nr 4 (18.02.2013): 437–45. http://dx.doi.org/10.1017/s1759078713000032.

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This paper presents a design method of internally-matched packaged GaN high electron mobility transistors (HEMTs) for achieving not only high-efficiency and high-power performances but also a wide bandwidth and insensitivity to harmonic terminations in the S-band. The package and its internal matching networks are synthesized to confine the second harmonic impedances seen by the GaN die to high-efficiency regions whatever the harmonic impedances presented outside the package. This paper reports the design of a packaged GaN HEMT achieving 78% of power-added-efficiency (PAE) and 25 W of output power at 2.5 GHz. A packaged GaN power bar is also reported with the addition of fundamental matching networks inside the package. In 50 Ω environment, the packaged GaN power bar provided more than 56% of PAE from 2.5 to 3.1 GHz and was desensitized to harmonic load variations with less than two points of PAE variation when a load-pull is performed at second harmonic frequencies outside the package.

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Chéron, Jérôme, Michel Campovecchio, Denis Barataud, Tibault Reveyrand, Michel Stanislawiak, Philippe Eudeline i Didier Floriot. "Electrical modeling of packaged GaN HEMT dedicated to internal power matching in S-band". International Journal of Microwave and Wireless Technologies 4, nr 5 (16.07.2012): 495–503. http://dx.doi.org/10.1017/s1759078712000530.

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The electrical modeling of power packages is a major issue for designers of high-efficiency hybrid power amplifiers. This paper reports the synthesis and the modeling of a packaged Gallium nitride (GaN) High electron mobility transistor (HEMT) associating a nonlinear model of the GaN HEMT die with an equivalent circuit model of the package. The extraction procedure is based on multi-bias S-parameter measurements of both packaged and unpackaged (on-wafer) configurations. Two different designs of 20 W packaged GaN HEMTs illustrate the modeling approach that is validated by time-domain load-pull measurements in S-band. The advantage of the electrical modeling dedicated to packaged GaN HEMTs is to enable a die-package co-design for power matching. Internal matching elements such as Metal oxide semiconductor (MOS) capacitors, Monolithic microwave integrated circuits (MMICs), and bond wires can be separately modeled to ensure an efficient optimization of the package for high power Radio frequency (RF) applications.

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Park, Jeong Hun, i Moon-Que Lee. "Harmonic Dual-Band Diode Mixer for the X- and K-Bands". Journal of Electromagnetic Engineering and Science 21, nr 1 (31.01.2021): 64–70. http://dx.doi.org/10.26866/jees.2021.21.1.64.

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This paper presents a new dual-band diode mixer for the X- and K-bands. The proposed mixer consists of a pair of series-connected diodes and a frequency-dependent delay line that operates at 180° and 360° at the X-band of 10.525 GHz and at the K-band of 24.15 GHz, respectively. Without reconfigurable devices such as switches, the proposed mixer operates as a single-balanced diode mixer at the X-band and a subharmonically pumped antiparallel diode mixer at the K-band simultaneously. The designed circuit was implemented in a hybrid microwave integrated circuit using discretely packaged RF components on a microwave printed circuit board. The measurement results showed conversion losses of 6.5 dB and 16.6 dB at the X- and K-bands, respectively.

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Skoulika, Stavroula G., i Constantinos A. Georgiou. "Rapid, Noninvasive Quantitative Determination of Acyclovir in Pharmaceutical Solid Dosage Forms through Their Poly(Vinyl Chloride) Blister Package by Solid-State Fourier Transform Raman Spectroscopy". Applied Spectroscopy 57, nr 4 (kwiecień 2003): 407–12. http://dx.doi.org/10.1366/00037020360625943.

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Fourier transform (FT) Raman spectroscopy based on band intensity or band area measurements was used for the quantitative determination of acyclovir in pharmaceutical solid dosage forms through their poly(vinyl chloride) blister package. Univariate calibration using the bands observed at 1690, 1630, 1574, 1482, 1181, 578, and 508 cm−1 was found to be sufficient for the analysis. Calibration curves were linear, the correlation coefficients being 0.997–0.9993 and 0.996–0.9991 for band intensity and band area measurements, respectively. Results obtained compare well, as indicated by the t-test, with those obtained by the current United States Pharmacopoeia (USP 24) and National Formulary (NF 19) method. Precision ranged from 0.7–4.5 and 0.4–4.0% RSD ( n = 3) for band intensity and band area measurements, respectively. The developed nondestructive FT-Raman method is rapid, simple, and can be used for the on-line, real-time monitoring of acyclovir formulation production lines.

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SOROKA, Elena Industrovna, Akhmet Askhatovich GALEEV, Vera Igorevna PETROVA, Vladimir Pavlovich LYUTOEV i Lubov’ Vladimirovna LEONOVA. "Dispersed organic matter characteristics as an indicator of rock alteration degree of the Safyanovskoe copper-sulphide deposit (Middle Urals)". NEWS of the Ural State Mining University 1, nr 1 (23.03.2020): 26–36. http://dx.doi.org/10.21440/2307-2091-2020-1-26-36.

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Relevance of the study is due to the importance of composition and maturity of the dispersed organic matter (DOM) as indicators of rock forming conditions, which may contribute to the paleoecological reconstruction of sedimentation conditions for rocks in the ore-bearing stratum of the Safyanovskoe deposit. Objective: to analyze the composition and characteristics of DOM in carbon-siliceous rocks of the ore-bearing stratum of the Safyanovsky copper-pyrite deposit. The obtained characteristics of the DOM make it possible to reveal the source of original accumulation and the level of its transformation under the influence of various geological processes. Methods. A detailed study of DOM was carried out by the EPR method (electron paramagnetic resonance) for powder preparations. EPR spectra were recorded at room temperature on X-band spectrometers DX-70, ESR 70-03 DX/2, and SE/X-2547 RadioPAN. The analytical procedure for studying organic matter (OM) included: determination of insoluble residue and C org content in the rock, extraction of the chloroform bitumoids (CB) and the alcohol-benzol bitumoids (ABB), humic acids (HA), determining the group composition of CB and hydrocarbons (HC), chromatographic fractionation with determination of the sum of methane-naphthenic and aromatic fractions of hydrocarbons, GC-MS analysis of n-alkanes, cyclic and polyaromatic hydrocarbons (PAHs). GC-MS analysis was performed on the complex Hewlett Packard 6850/5973 with a quadrupole mass detector and analytical information processing software. Results. Analysis of the EPR spectra of carbon-siliceous rocks of the Safyanovskoe deposit showed the presence of the two types of carbon signal (C-org), characteristic of the plant and the animal residues. It was also found that the DOM has never been exposed to temperatures greater than 300 °C. Geochemical analysis of OM indicates that DOM is at a high maturation stage (residual organic matter (ROM) > 99%). But the type of distribution of polyaromatic hydrocarbons (PAHs) suggests that the primary OM was specifically altered at elevated temperatures. Conclusions. DOM of carbon-siliceous rocks of the Safyanovsky deposit is genetically the same, its type is mainly sapropelic and accumulation is associated with marine conditions. A characteristic feature is, on the one hand, its high polymerization, which is typical for DOM of the stage of late mesocatagenesis, and, on the other hand, its molecular composition does not allow us to talk about the maturation of DOM in the process of natural regional metamorphism.

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Zhen, Shuchen, Yongle Wu, Shaobo Li, Zhuoyin Chen i Weimin Wang. "A Dual-Band Dual-Output Filtering Power Amplifier Based on High-Selectivity Filtering Impedance Transformer". International Journal of RF and Microwave Computer-Aided Engineering 2023 (15.06.2023): 1–10. http://dx.doi.org/10.1155/2023/5240745.

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In this brief, a novel filtering impedance transformer with good selectivity and high termination impedance is proposed, of which close-formed design equations are derived and effectively verified. Then, a dual-band dual-output filtering power amplifier (PA) operating at 2.4-2.6 GHz and 3.4-3.6 GHz is designed based on the proposed filtering impedance transformer. The dual-band filtering PA contains a diplexer-like output matching network, which can separate two band signals into corresponding output branches. EM-simulated results of the diplexer-like output matching network show that the isolation between the two output ports is better than 30.7 dB. Finally, for demonstration, the dual-band dual-output filtering PA using a packaged 10 W transistor is fabricated, and the measured drain efficiencies are 45.3%-50.2% and 41.7%-53.2% at lower and higher bands, respectively. Also, a good dual-band filtering response is obtained. A good agreement between simulated and measured results is observed.

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Al-Dwairi, Majed O. "A planar UWB semicircular-shaped monopole antenna with quadruple band notch for WiMAX, ARN, WLAN, and X-Band". International Journal of Electrical and Computer Engineering (IJECE) 10, nr 1 (1.02.2020): 908. http://dx.doi.org/10.11591/ijece.v10i1.pp908-918.

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This paper proposed quadruple notched frequency bands ultra-wideband (UWB) antenna. The antenna is a semicircular-shaped monopole type of a compact size 36x24 mm, covering frequency range of 3.02-14 GHz. Four rejected narrow bands including WiMAX (3.3-3.7GHz), ARN (4.2-4.5 GHz), WLAN (5.15-5.825GHz), X-Band (7.25-7.75) have been achieved using inserting slots techniques in the patch, feed line, and ground plane. The slots dimensions have been optimized for the required reject bands. The antenna design and analysis have been investigated by simulation study using CST-EM software package. The antenna characteristics including impedance bandwidth, surface current, gain, radiation efficiency, radiation pattern have been discussed.

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Ali, Waqas, N. Nizam-Uddin, Wazie M. Abdulkawi, Asad Masood, Ali Hassan, Jamal Abdul Nasir i Munezza Ata Khan. "Design and Analysis of a Quad-Band Antenna for IoT and Wearable RFID Applications". Electronics 13, nr 4 (8.02.2024): 700. http://dx.doi.org/10.3390/electronics13040700.

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The role of antennas in wireless communication is critical for enabling efficient signal transmission and reception across various frequency bands, including those associated with IoT (Internet of Things), X-band, S-band, and RFID (radio-frequency identification) systems. This paper presents a small quadruple-band antenna with 25 × 40 × 1.5 mm3 dimensions designed for diverse wireless applications. It is adept at operating in the S-band (2.2 GHz), wireless local area network (WLAN) (5.7 GHz), microwave RFID frequency band (5.8 GHz), and X-band (7.7 GHz and 8.3 GHz). While the majority of existing research focuses on antennas covering two or three bands, our work stands out by achieving quad-band operation in the proposed antenna design. This antenna is constructed on a semiflexible Rogers RT5880 substrate, making it well-suited for wearable applications. Computer Simulation Technology (CST) Microwave studio (2019) simulation package software is chosen for design and analysis. The antenna design features a comb-shaped radiating structure, where each “tooth” is responsible for resonating at a distinct frequency with an appropriate bandwidth. The antenna retains stability in both free space and on-body wearability scenarios. It achieves a low specific absorption rate (SAR), meeting wearable criteria with SAR values below 1.6 W/Kg for all resonating frequencies. The proposed antenna demonstrates suitable radiation efficiency, reaching a maximum of 82.6% and a peak gain of 6.3 dBi. It exhibits a bidirectional pattern in the elevation plane and omnidirectional behavior in the azimuth plane. The antenna finds applications across multiple frequencies and shows close agreement between simulated and measured results, validating its effectiveness.

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Atasever, Oznur, i Sinem Erdem. "Molecular Characterization of Service Tree (Sorbus domestica L.) Genotypes Selected from Tokat Province". Proceedings of the Bulgarian Academy of Sciences 75, nr 8 (31.08.2022): 1227–33. http://dx.doi.org/10.7546/crabs.2022.08.16.

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This study was carried out to determine the genetic diversity of eleven service tree (Sorbus domestica L.) genotypes selected from Tokat province and taken under protection in the genetic resource plot. In the present study, ISSR-PCR studies were carried out on genotype DNAs obtained by Mini-CTAB method and the level of polymorphism between genotypes was determined us- ing seven UBC-ISSR primers. A total of 65 bands were obtained in service tree genotypes with seven primers and 56 of these bands were determined to be polymorphic. The number of bands obtained per primer varied between 5 and 12, the mean band number was 5.90, and the mean polymorphic band number was 5.09. The data obtained as a result of the evaluation of ISSR-PCR bands were analyzed in Popgene32 and MEGA5.0 computer package program, and a dendrogram was obtained according to the UPGMA method. In the dendro- gram obtained, it was determined that two groups were formed at the level of approximately 22% difference, and there was only one genotype in the small group while the other genotypes were in the large group.

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Lacalli, T. C., i J. E. West. "Ciliary band formation in the doliolaria larva of Florometra". Development 96, nr 1 (1.07.1986): 303–23. http://dx.doi.org/10.1242/dev.96.1.303.

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The development of ciliary band pattern in the doliolaria larva of Florometra serratissima is described based on scanning and transmission electron microscopy. The uniformly ciliated epithelium of the post-hatching larva develops four regularly spaced bands over a period of approx. 20 h generating an epithelial pattern that is, essentially, a series of stripes. The first visible events of pattern formation progress over the larval surface in a posterior-to-anterior and dorsal-to-ventral sequence, but the initial pattern is not, in fact, striped. It instead consists of a close-packed array of oval interband domains separated and surrounded by belts of band cells. Secondarily the interband domains expand laterally and coalesce to form continuous, broad stripes, while the bands remain as narrow stripes between them. Two possible explanations for this unusual sequence of events are discussed: (1) that it can be understood in evolutionary terms with reference to band pattern in other echinoderm larvae, and (2) that it is a morphogenetic necessity because limitations inherent in the patterning mechanism prevent the direct formation of regular stripes.

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Choi, Dong Hee, Yong Min Kwon, Hiroshi Xavier Chiura, Eun Chan Yang, Seung Seob Bae, Sung Gyun Kang, Jung-Hyun Lee, Hwan Su Yoon i Sang-Jin Kim. "Extracellular Vesicles of the Hyperthermophilic Archaeon “Thermococcus onnurineus” NA1T". Applied and Environmental Microbiology 81, nr 14 (1.05.2015): 4591–99. http://dx.doi.org/10.1128/aem.00428-15.

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ABSTRACTExtracellular vesicles (EVs) produced by a sulfur-reducing, hyperthermophilic archaeon, “Thermococcus onnurineus” NA1T, were purified and characterized. A maximum of four EV bands, showing buoyant densities between 1.1899 and 1.2828 g cm−3, were observed after CsCl ultracentrifugation. The two major EV bands, B (buoyant density at 25°C [ρ25] = 1.2434 g cm−3) and C (ρ25= 1.2648 g cm−3), were separately purified and counted using a qNano particle analyzer. These EVs, showing different buoyant densities, were identically spherical in shape, and their sizes varied from 80 to 210 nm in diameter, with 120- and 190-nm sizes predominant. The average size of DNA packaged into EVs was about 14 kb. The DNA of the EVs in band C was sequenced and assembled. Mapping of theT. onnurineusNA1TEV (ToEV) DNA sequences onto the reference genome of the parent archaeon revealed that most genes ofT. onnurineusNA1Twere packaged into EVs, except for an ∼9.4-kb region from TON_0536 to TON_0544. The absence of this specific region of the genome in the EVs was confirmed from band B of the same culture and from bands B and C purified from a different batch culture. The presence of the 3′-terminal sequence and the absence of the 5′-terminal sequence of TON_0536 were repeatedly confirmed. On the basis of these results, we hypothesize that the unpackaged part of theT. onnurineusNA1Tgenome might be related to the process that delivers DNA into ToEVs and/or the mechanism generating the ToEVs themselves.

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Andrade, A. C., M. J. Alixandrini Jr., F. P. S. Carvalho i V. O. Fernandes. "PERFORMANCE OF THE SUPPORT VECTOR MACHINE AND ARTIFICIAL NEURAL NETWORK CLASSIFIERS FOR ROADS IDENTIFICATION". International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B3-2021 (28.06.2021): 9–14. http://dx.doi.org/10.5194/isprs-archives-xliii-b3-2021-9-2021.

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Abstract. The objective of this project was to compare two non-parametric classification methods (“Support Vector Machine” – SVM and “Artificial Neural Networks” – ANN) of road regions in high spatial resolution images and associated with data from Airborne Laser Scanning. The study aims to verify what kind of influence the layers of attributes have on the performance from respective classifiers: SVM and RNA. Our method based on tests of this classifiers on 4 bands of airborne images and normalization of the digital surface model (DSM) for showing only information on objects height in relation to ground and not of these in relation to the ground and relief, generating band 5. The samples were used to train chosen non-parametric classifiers (training sets for each different input image/landscape). All classifications had the same set of training samples and the same classification parameters. The optimal parameters for classifications were obtained through the existing library in the Weka mining package: LibSVM and LibMultiLayerPerceptron. Our results demonstrated the existence of a direct relationship between the elevation band of the targets in relation to the terrain (band 05) with the improvement of their performance and lower degree of between bands correlation can also be considered a factor that has a positive influence. As for Neural Networks, the experiment results demonstrate that the presence of the near infrared band (band 04) was decisive for the performance improving of certain combinations in relation to others.

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Zhang, Wen Bin, Yan Ping Su, Yan Jie Zhou i Ya Song Pu. "Intelligent Gear Fault Identification Method Based on Harmonic Wavelet Package Energy Distribution and Grey Incidence". Advanced Materials Research 694-697 (maj 2013): 1155–59. http://dx.doi.org/10.4028/www.scientific.net/amr.694-697.1155.

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In this paper, a novel intelligent method to identify gear fault pattern was approached based on morphological filter, harmonic wavelet package and grey incidence. At first, the line structure element was selected for morphological filter to denoise the original signal. Secondly, different gear fault signals were decomposed into eight frequency bands by harmonic wavelet package in three levels; and energy distribution of each band was calculated. Finally, these energy distributions could serve as the feature vectors, the grey incidence of different gear vibration signals was calculated to identify the fault pattern and condition. Practical results show that this method can be used in gear fault diagnosis effectively.

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Zhang, Wen Bin, Yan Ping Su, Yan Jie Zhou i Jie Min. "Intelligent Gear Fault Recognition Method Based on HWP Sample Entropy and Grey Incidence". Advanced Materials Research 706-708 (czerwiec 2013): 1397–400. http://dx.doi.org/10.4028/www.scientific.net/amr.706-708.1397.

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In this paper, a novel method to recognize gear fault pattern was approached based on harmonic wavelet package (HWP), sample entropy and grey incidence. At first, the line structure element was selected for rank-order morphological filter to denoise the original signal. Secondly, different gear fault signals were decomposed into eight frequency bands by harmonic wavelet package in three levels; and sample entropy of each band was calculated. Finally, these sample entropies could serve as the feature vectors, the grey incidence of different gear vibration signals was calculated to identify the fault pattern and condition. Practical results show that this method can be used in gear fault diagnosis effectively.

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Miller, W. R., R. E. McDonald i T. E. Cracker. "Quality of Two Florida Blueberry Cultivars after Packaging and Storage". HortScience 28, nr 2 (luty 1993): 144–47. http://dx.doi.org/10.21273/hortsci.28.2.144.

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Blueberry cultivars Sharpblue (mainly Vaccinium corymbosum L.) and Climax (V. ashei L.) were band-harvested on three occasions and manually packaged into 0.275 liter fiber-pulp cups or automatically packaged in vented polystyrene cups. Berries were evaluated after 1,2, or 3 weeks of storage at 1C and after 2 additional days of storage at 16C, a time frame that simulated a merchandising period. Weight loss of fruit packaged in polystyrene cups was <1% during 3 weeks of storage at 1C, whereas weight loss of berries packaged in fiber-pulp cups was ≈5.0% after similar storage. `Sharpblue' berries were softer at harvest and after each storage duration than `Climax' berries. Decay increased to ≈7% for `Climax' and 28% for `Sharpblue' after 3 weeks of storage at 1C. Package type did not affect decay incidence after 3 weeks of storage; but after 2 additional days at 16C, decay incidence was slightly higher for berries packaged in polystyrene compared with those packaged in fiber-pulp cups. `Sharpblue' should be packaged only in fiber-pulp cups and marketed quickly after harvest to avoid excessive decay.

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Dong, Guo Yan, i Ji Zhou. "Anomalous Optical Transmission Phenomena in Photonic Crystals". Applied Mechanics and Materials 320 (maj 2013): 128–32. http://dx.doi.org/10.4028/www.scientific.net/amm.320.128.

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Anomalous optical transmission phenomena have ever been discovered in various metamaterials, which can be modulated more easily in Photonic crystals (PhCs). Compared with the regular PhCs composed of round rods closely packed in air, the equal frequency contours (EFC) of honeycomb lattice PhCs constituted by trigonal rods are more rounded and more suitable to realize the all-angle left-handed negative refraction (AALNR) in the low band region. Due to the hex EFC distribution, the regular PhC can be applied in the optical collimator design. In the higher band regions, the more complicated refraction behaviors can be excited based on the intricate undulation of one band or the overlap of different bands in PhCs. These unique features will provide us with more understanding of electromagnetic wave propagation in PhCs and give important guideline for the design of new type optical devices.

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Doan Thi Kieu, Anh, Linh Tran Phan Thuy i Mui Luong Viet. "A THEORETICAL STUDY OF THE CRYSTAL STRUCTURES AND ELECTRONIC PROPERTIES OF BULK MoS2 AND ITS MONOLAYER BASED ON FIRST – PRINCIPLES CALCULATION". Journal of Science Educational Science 66, nr 5A (grudzień 2021): 198–206. http://dx.doi.org/10.18173/2354-1075.2021-0230.

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In this work, we have investigated the structural and electronic properties of both bulk and monolayer MoS2 based on the density functional theory (DFT) implemented in the CASTEP of Materials Studio package. The calculations are performed with the local density approximation (LDA) and generalized gradient approximation (GGA) functionals for crystal structure optimization and band structure of MoS2 bulk and monolayer. Our calculations show that the GGA functional calculated excellent band gap for bulk MoS2, while LDA functional is found to perform better for band gap calculations of a monolayer. The influence of composition in the energy bands has been realized by analyzing the partial density of states (PDOS) of each atom and density of states (DOS). By reducing the layer thickness from bulk to monolayer, it is found that band structure has the transitions from indirect band gap in the bulk MoS2 (1.53 eV) to direct band gap in the monolayer (1.82 eV). On the other hand, the charge density difference along z-direction shows that the major charge transfer occurs on the surface of the S atoms and there is a little accumulation around the surface of the Mo atoms. This property highlights the promising of MoS2 in improving the fabrication of optoelectronic devices in the future.

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Kitazawa, K., S. Koriyama, H. Minamiue i M. Fujii. "77-GHz-band surface mountable ceramic package". IEEE Transactions on Microwave Theory and Techniques 48, nr 9 (2000): 1488–91. http://dx.doi.org/10.1109/22.868999.

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House, Peggy. "An Extension: Gather Your Students around the Gathering Circles". Mathematics Teacher 93, nr 9 (grudzień 2000): 751–52. http://dx.doi.org/10.5951/mt.93.9.0751.

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You and your students can investigate arrangements of tightly packed circles by using drinking straws and string or rubber bands. Wrap the string or band loosely around a handful of straws, and pull it taut. Observe the way that the straws align on the end when the string is pulled as tightly as possible. See figure 1. Looking at the cross section of the bundle of straws, notice that the centers of the circles and the points of tangency form the lattice points of an isometric grid, as shown in figure 2. You can use isometric paper to record the “packed” arrangements of various numbers of circles (fig. 3).

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Li, Yongjiu, Long Li, Xiwang Dai, Cheng Zhu, Feifei Huo i Gang Dong. "Compact Shorted Stacked-Patch Antenna Integrated with Chip-Package Based on LTCC Technology". International Journal of Antennas and Propagation 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/235847.

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A low profile chip-package stacked-patch antenna is proposed by using low temperature cofired ceramic (LTCC) technology. The proposed antenna employs a stacked-patch to achieve two operating frequency bands and enhance the bandwidth. The height of the antenna is decreased to 4.09 mm (aboutλ/25 at 2.45 GHz) due to the shorted pin. The package is mounted on a 44 × 44 mm2ground plane to miniaturize the volume of the system. The design parameters of the antenna and the effect of the antenna on chip-package cavity are carefully analyzed. The designed antenna operates at a center frequency of 2.45 GHz and its impedance bandwidth(S11< -10 dB)is 200 MHz, resulting from two neighboring resonant frequencies at 2.41 and 2.51 GHz, respectively. The average gain across the frequency band is about 5.28 dBi.

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Ali, M., T. Sittironnarit, H. S. Hwang, R. A. Sadler i G. J. Hayes. "Wide-Band/Dual-Band Packaged Antenna for 5–6 GHz WLAN Application". IEEE Transactions on Antennas and Propagation 52, nr 2 (luty 2004): 610–15. http://dx.doi.org/10.1109/tap.2004.823992.

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Sharma, Sachin, Sanjay Prakash Kaushik, Ram-Krishna Thakur i Vivek Kumar Shukla. "Study of Structural Properties of Solar Energy Material CH3 NH3 PbX3 (X= I, Br and Cl) Perovskites and its Mixed Halides Using Density Functional Theory". Nepal Journal of Science and Technology 21, nr 2 (31.12.2022): 105–14. http://dx.doi.org/10.3126/njst.v21i2.62360.

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The present study has explored the electronic properties of Organic-inorganic mixed halide-based perovskites using density functional theory. The Quantum Espresso simulation package with PBE parameterization within the generalized gradient approximation (GGA) has been used in this work. The findings reveal that the addition of halogens (bromide and chlorine) to compound CH3NH3PbI3 for all the possible substituted halides may cause the shifting of energy bands in the band structure and thus change the bandgap. Hence, this calculation may be used to design perovskite solar cell material with varied electronic structure.

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Tian, Yin, Guangming Wang, Yexi Song, Jie Yang, Yu Cao, Wei Tong, Yijun Chen i Shiwen Tang. "A compact Ka-band antenna-in-package for system-in-package application". IEICE Electronics Express 14, nr 12 (2017): 20170444. http://dx.doi.org/10.1587/elex.14.20170444.

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Mezaal, Y. S., H. H. Saleh i H. Al-saedi. "New Compact Microstrip Filters Based on Quasi Fractal Resonator". Advanced Electromagnetics 7, nr 4 (3.09.2018): 93–102. http://dx.doi.org/10.7716/aem.v7i4.883.

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This paper presents new microstrip devices as single band bandpass and multi band bandstop filters. The proposed filters use slotted patch microstrip resonator based on quasi fractal geometry, simulated by AWR12 software package. Both filters have quasi elliptic frequency response, designed at centre frequency of 2.437 GHz for bandpass filter and at band frequencies of 2.434, 4.032, 4.976 and 5.638 GHz GHz respectively, for multi bandstop filter. All filters are employed using RT/Duroid 6010.8 LM substrate of dielectric constant and 1.27 mm dielectric thickness. Simulation results show that the designed quasi fractal bandpass filter has very narrow fractional bandwidth of 0.38 % which is very rare in microstrip filter design. On the other hand, the projected bandstop filter offers multi narrow rejection bands that is useful in broadband wireless schemes influencing from fixed interferences. Both filters present satisfactory S11 and S21 responses besides smallness properties that stand for interesting features of the newest wireless applications. The simulated and measured frequency responses for both designed filters are in good agreement.

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Rymanov, V., M. Palandöken, S. Dülme, T. Tekin i A. Stöhr. "Compact Photonic Package for High-Power E-Band (60–90 GHz) Photoreceiver Modules". International Symposium on Microelectronics 2013, nr 1 (1.01.2013): 000883–86. http://dx.doi.org/10.4071/isom-2013-thp43.

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In this work, we present a novel photonic package for high-power photoreceiver modules operating within the E-band (60–90 GHz). The developed Kovar package features a compact size of only 6×3.5×2 cm3 and comprises an optical single-mode fiber (SMF) input, DC bias supply connections and a WR-12 output for coupling out of the radio frequency (RF) signal. As integration platform, a RF laminate submount with implemented planar bias-T based upon grounded coplanar waveguide (GCPW) transmission line circuitry is used for efficient mmW propagation, concluding in a GCPW-to-WR-12-transition. Finite element method (FEM) simulations have been carried out to analyze the frequency range of interest. Besides applied adhesive and wire bonding approaches for assembly inside the package, the RF submount exhibits sections for hybrid integration of single components, e.g. of a high-frequency waveguide photodiode. Optionally, up to two high-electron-mobility-transistor (HEMT) power amplifiers can be integrated within the GCPW circuitry. In addition, the RF laminate is mounted on a brass platform. For uniform thermal expansion within the module, a Peltier element is integrated. Concerning the saturation output power of given HEMT amplifiers, e.g. in the order of +17.5 dBm, corresponding power levels are achievable for packaged devices. For instance, an output RF power of only −19.5 dBm within the 71–76 GHz band is required from the photodiode in conjunction with two cascaded HEMT amplifiers, which results in a total gain of ~37 dB. A small series of the introduced device has been already fabricated. First experimental achievements with in-house fabricated modules will be presented.

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Yin, Bangsheng, Qilong Min, Emily Morgan, Yuekui Yang, Alexander Marshak i Anthony B. Davis. "Cloud-top pressure retrieval with DSCOVR EPIC oxygen A- and B-band observations". Atmospheric Measurement Techniques 13, nr 10 (6.10.2020): 5259–75. http://dx.doi.org/10.5194/amt-13-5259-2020.

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Abstract. An analytic transfer inverse model for Earth Polychromatic Imaging Camera (EPIC) observations is proposed to retrieve the cloud-top pressure (CTP) with the consideration of in-cloud photon penetration. In this model, an analytic equation was developed to represent the reflection at the top of the atmosphere from above cloud, in cloud, and below cloud. The coefficients of this analytic equation can be derived from a series of EPIC simulations under different atmospheric conditions using a nonlinear regression algorithm. With estimated cloud pressure thickness, the CTP can be retrieved from EPIC observation data by solving the analytic equation. To simulate the EPIC measurements, a program package using the double-k approach was developed. Compared to line-by-line calculation, this approach can calculate high-accuracy results with a 100-fold computation time reduction. During the retrieval processes, two kinds of retrieval results, i.e., baseline CTP and retrieved CTP, are provided. The baseline CTP is derived without considering in-cloud photon penetration, and the retrieved CTP is derived by solving the analytic equation, taking into consideration in-cloud and below-cloud interactions. The retrieved CTPs for the oxygen A and B bands are smaller than their related baseline CTP. At the same time, both baseline CTP and retrieved CTP at the oxygen B band are larger than those at the oxygen A band. Compared to the difference in baseline CTP between the B band and A band, the difference in retrieved CTP between these two bands is generally reduced. Out of around 10 000 cases, in retrieved CTP between the A and B bands we found an average bias of 93 mb with a standard deviation of 81 mb. The cloud layer top pressure from Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) measurements is used for validation. Under single-layer cloud situations, the retrieved CTPs for the oxygen A band agree well with the CTPs from CALIPSO, the mean difference of which within 5 mb in the case study. Under multiple-layer cloud situations, the CTPs derived from EPIC measurements may be larger than the CTPs of high-level thin clouds due to the effect of photon penetration.

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Fadhel, Yasser A. "A Dual-band Planar Antenna for Wireless Local Area Network Applications". Polytechnic Journal 9, nr 2 (1.12.2019): 105–11. http://dx.doi.org/10.25156/ptj.v9n2y2019.pp105-111.

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Wireless local area network (WLAN) communication is one of the fast and secure wireless technologies, which is vastly used in nowadays portable and handheld devices. This paper is oriented on designing of a planar WLAN antenna to serve in WLAN network devices. The designed antennas are single and dual-band planar monopole antennas to be working at IEEE 802.11 WLAN frequencies; 2.45 GHz and 5.2/5.8 GHz bands. Different configurations have been used in the design process, especially for the dual-band antenna, where dual-resonant is required. The antennas have been designed analytically then simulated using the CST software package. Simulation results for the input reflection coefficient, realized gain, and radiation pattern have been considered to evaluate their features. The antennas have also been fabricated practically and practical measurements for the input reflection coefficient and radiation pattern have been taken which shown a good agreement with those of simulation.

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30

Moronval, Xavier, Reza Abdoelgafoer i Adeline Déchansiaud. "MMIC-based asymmetric Doherty power amplifier for small cells applications". International Journal of Microwave and Wireless Technologies 7, nr 5 (3.06.2014): 499–505. http://dx.doi.org/10.1017/s1759078714000737.

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We present the results obtained on a multi-mode multi-band 20 W Monolithic Microwave Integrated Circuit (MMIC) power amplifier. The proposed two-stage circuit is based on the silicon Laterally Diffused Metal Oxide Semiconductor (LDMOS) technology. Thanks to dedicated design techniques, it can cover the Digital Cellular Service (DCS), Personal Communications Service (PCS), and UMTS bands (ranging from 1.805 to 2.17 GHz) and deliver more than 20 W of output power, 30 dB of gain and 50% of power added efficiency. When combined in a Doherty configuration with an incremental 40 W MMIC in a dual-path package, the resulted asymmetric MMIC (an industry first) can deliver an unprecedented LDMOS MMIC efficiency of up to 44% at 8 dB back-off in the UMTS band. Then, the DPA has been optimized in conjunction with a novel RF pre-distortion technique, leading to 33–80% energy saving at the system level.

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Alhenawy, Mahmoud, i Martin Schneider. "Antenna-in-package (AiP) in mm-wave band". International Journal of Microwave and Wireless Technologies 5, nr 1 (23.01.2013): 55–64. http://dx.doi.org/10.1017/s1759078712000815.

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We studied the viability of the embedded wafer level ball grid array (eWLB) package environment as an antenna platform for 77 GHz automotive radar sensors and the effects of package fabrication tolerances on the antenna performance. The investigation of different antenna concepts in the eWLB package and their characterization methods are addressed. The design procedures for electrically large, differentially fed loop antennas in a multilayer package structure are introduced. Two different planar antennas are developed and measured in an eWLB package showing promising results such as a gain of 9 GHz and an impedance bandwidth of 8 GHz. An acceptable antenna performance is recorded within the tolerance limits. Therefore, the eWLB package is seen as an appropriate platform for mm-wave antennas and as a good candidate for an antenna-in-package (AiP) concept.

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32

Alvarado-Canche, Carmen Natividad, Francisco Castillo Reyes, Víctor Manuel González-Vázquez, Oswaldo Garcia-Martinez, Luis Alberto Aguirre-Uribe, Miguel Angel Tiscareño-Iracheta, Cristóbal Noé Aguilar-González i Raúl Rodríguez-Herrera. "Population genetics of lepidopteran (noctuidae) collected on transgenic and non-transgenic maize in Mexico". Acta Universitaria 29 (29.04.2019): 1–12. http://dx.doi.org/10.15174/au.2019.1926.

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Allele frequency of the resistance of the gene Onb3GalT5 to Cry proteins was analyzed in insect populations (Helicoverpa zea and Heliothis virescens), collected from maize transgenic and non-transgenic plants. The genetic parameters estimated in these populations were allele and genotype frequency, genetic balance and Wright statistics (Fis, Fit and Fst). Statistical analyses were performed using the package Genepop (4.0.10). Results showed that from the DNA of H. virescens, collected on non-transgenic maize, a higher number of bands were amplified in a range from 250 bp to 600 bp. In contrast, the bands amplified from insects collected on transgenic maize were in the range of 250 bp-500 bp, being the 400 bp band in both cases the most frequent, while in the DNA of Helicoverpa zea, collected on transgenic maize, three bands (350 bp, 400 bp and 450 bp) were amplified, and in H. zea, collected on non-transgenic maize, only two bands (350 bp and 400 bp) were observed. Genetic diversity in insect populations was higher than within these same populations.

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33

Ishfaq, Muhammad Kamran, Tharek Abd Rahman, Hassan Tariq Chattha i Masood Ur Rehman. "Multiband Split-Ring Resonator Based Planar Inverted-F Antenna for 5G Applications". International Journal of Antennas and Propagation 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/5148083.

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5G, the fifth generation of wireless communications, is focusing on multiple frequency bands, such as 6 GHz, 10 GHz, 15 GHz, 28 GHz, and 38 GHz, to achieve high data rates up to 10 Gbps or more. The industry demands multiband antennas to cover these distant frequency bands, which is a task much more challenging. In this paper, we have designed a novel multiband split-ring resonator (SRR) based planar inverted-F antenna (PIFA) for 5G applications. It is composed of a PIFA, an inverted-L parasitic element, a rectangular shaped parasitic element, and a split-ring resonator (SRR) etched on the top plate of the PIFA. The basic PIFA structure resonates at 6 GHz. An addition of a rectangular shaped parasitic element produces a resonance at 15 GHz. The introduction of a split-ring resonator produces a band notch at 8 GHz, and a resonance at 10 GHz, while the insertion of an inverted-L shaped parasitic element further enhances the impedance bandwidth in the 10 GHz band. The frequency bands covered, each with more than 1 GHz impedance bandwidth, are 6 GHz (5–7 GHz), 10 GHz (9–10.8 GHz), and 15 GHz (14-15 GHz), expected for inclusion in next-generation wireless communications, that is, 5G. The design is simulated using Ansys Electromagnetic Suite 17 simulation software package. The simulated and the measured results are compared and analyzed which are generally in good agreement.

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Brinkfeldt, K., T. Åklint, C. Sandberg, P. Johander i D. Andersson. "High Temperature Packaging for SiC Power Transistors". International Symposium on Microelectronics 2012, nr 1 (1.01.2012): 001124–30. http://dx.doi.org/10.4071/isom-2012-thp36.

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Power transistors based on silicon carbide (SiC) are now commercially available. They have a higher efficiency and higher voltage blocking capabilities than conventional silicon devices. The wide-band gap and chemical inertness of SiC makes it suitable to high temperature operation. However, there is a need for new packaging for power transistors that can operate in higher temperatures. We have developed a package based on ceramics and silver for high temperature operation of SiC power transistors. Three types of SiC devices from different manufacturers are packaged and tested in room temperature. Though the devices were still functional after the packaging process, their performance seem to have degraded. This could be a result of the high temperature packaging process and the measurement setup. FEM simulations are also performed to investigate the thermo-mechanical behavior of the package. The target operating temperature of the package is 400 °C. Modeling show stress concentrations at the corners of the device chip and suggests that this stress is decreased if the substrate metallization is changed from copper to silver.

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35

Shukla, Nishant, Pawan Chetri i Gazi A. Ahmed. "A Newly Developed Dispersive Interaction Approach, DFT-D3, to the Three-Dimensional Topological Host Material Sb<sub>2</sub>Te<sub>3</sub>". Materials Science Forum 1065 (30.06.2022): 195–202. http://dx.doi.org/10.4028/p-pgnl37.

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Antimony Telluride (Sb2Te3), a topological insulator is a layered semiconductor material with hexagonal unit cell similar to graphene. The characteristic presence of their conducting edges or surfaces with self-induced protection, promise for remarkable future applications. In this exertion based on the first principle approach, the structural and electronic properties of Sb2Te3 compound have been investigated for both without and with spin orbit coupling (SOC). Lattice structure, band structure, total density of states (TDOS), partial density of states (PDOS), energy bands of surface states are determined within Quantum Espresso simulation package. Furthermore, dispersive interactions, induced due to the presence of van-der-Waals forces have also been taken care of. The newly developed method of DFT-D3 has been incorporated for accurate predictions of band gap and lattice parameters. A proficient model, TheSlabModel, has been used to observe the presence of single Dirac cone on the surface. To our knowledge, our theoretical investigations are valid and are found to be congruous with the observed data.

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36

Doo, Jihoon, Jongyoun Kim i Jinho Jeong. "D-Band Frequency Tripler Module Using Anti-Parallel Diode Pair and Waveguide Transitions". Electronics 9, nr 8 (27.07.2020): 1201. http://dx.doi.org/10.3390/electronics9081201.

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In this paper, D-band (110–170 GHz) frequency tripler module is presented using anti-parallel GaAs Schottky diode pair and waveguide-to-microstrip transitions. The anti-parallel diode pair is used as a nonlinear device generating harmonic components for Q-band input signal (33–50 GHz). The diode is zero-biased to eliminate the bias circuits and thus minimize the number of circuit components for low-cost hybrid fabrication. The anti-parallel connection of two identical diodes effectively suppresses DC and even harmonics in the output. Furthermore, the first and second harmonics of Q-band input signal are cut off by D-band rectangular waveguide. Input and output impedance matching networks are designed based on the optimum impedances determined by harmonic source- and load-pull simulations using the developed nonlinear diode model. Waveguide-to-microstrip transitions at Q- and D-bands are also designed using E-plane probe to package the frequency tripler in the waveguide module. The compensation circuit is added to reduce the impedance mismatches by bond-wires connecting two separate substrates. The fabricated frequency tripler module produces a maximum output power of 5.4 dBm at 123 GHz under input power of 20.5 dBm. A 3 dB bandwidth is as wide as 22.5% from 118.5 to 148.5 GHz at the input power of 15.0 dBm. This result corresponds to the excellent bandwidth performance with a conversion gain comparable to the previously reported frequency tripler operating at D-band.

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Liu, Feng, Jiayin Guo, Luyu Zhao, Guan-Long Huang, Yingsong Li i Yingzeng Yin. "Dual-Band Metasurface-Based Decoupling Method for Two Closely Packed Dual-Band Antennas". IEEE Transactions on Antennas and Propagation 68, nr 1 (styczeń 2020): 552–57. http://dx.doi.org/10.1109/tap.2019.2940316.

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Kurita, Hisatsugu, Masataka Nakamura, Hayato Miyagawa i Yoshiaki Kamigaki. "Effect of N₂-Anneal Temperature on Silicon Nitride Film: (I) Time-Dependent Dielectric Breakdown and ESR Evaluations". ECS Meeting Abstracts MA2022-01, nr 28 (7.07.2022): 1250. http://dx.doi.org/10.1149/ma2022-01281250mtgabs.

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Silicon Nitride (SiN) film has been used as insulating material in many electronic devices such as capacitors and memories . In this report, the effect of N2 anneal temperature on charge break down (Qbd) of LP-CVD SiN film was electrically evaluated using the time-dependent dielectric breakdown (TDDB) test method, and the variation and the density of defects which exist in SiN film, in the oxide layer between SiN and Si substrate, and at the surface of Si substrate, were investigated using an Electron Spin Resonance (ESR) to reveal the defect behavior related to the trigger of Qbd. SiN metal-insulator-metal (MIM) capacitors were fabricated to evaluate TDDB. A 54 nm dielectric layer of SiN film was deposited at 700 degree-C, using a mixture of dichlorosilane（SiH2Cl2）and ammonia (NH3) gasses, by a LP-CVD vertical furnace. For the lower and upper electrode, a 400 nm polycrystalline silicon films were deposited using a LP-CVD. In order to evaluate the effect of anneal temperature on SiN film breakdown frequency, these samples were annealed in nitrogen atmosphere at temperatures between 700 and 1150 degree-C for 1 hour, using a vertical furnace. Breakdown voltage was measured with a current-voltage tester (HP4071A, Hewlett Packard) for each SiN MIM capacitor. The breakdown frequency was defined as the ratio of failed capacitors to tested capacitors. For the TDDB measurements, a constant current stress of 1.33 A/cm2 was applied to the MIM capacitors with the area of 0.00375cm2, 0.0075cm2, 0.015cm2 and 0.03cm2. For each area, 100 chips were made from one wafer and measured. In Fig.1, SiN film breakdown frequency increases toward a peak at around the N2 anneal temperature of 900 degree-C, then decreases at 1000 degree-C, and at more than 1100 degree-C, the frequency increases again drastically at 1150 degree-C. SiN films for ESR study were fabricated on Si wafer in the same LP-CVD process, and annealed in nitrogen atmosphere at temperatures between 700 and 1150 degree-C for 1 hour, using a vertical furnace. The ESR measurements were performed at room temperature using an X-band spectrometer (JES-RE1X). To improve the signal-to-noise ratio of an ESR signal waveform, we set the accumulation number of magnetic-field (H) sweep about 300 times. Mn2+/ MgO hyperfine lines were used for the g marker, and spin densities were determined by using the standard of known spin content. In Fig.2, Dangling bond density at silicon interface (Pb center) has a peak at 900 degree-C, and those in SiO2 (E’ center) and SiN film (K center) increase with increasing temperature from 1000 to 1150 degree-C. The former phenomena of Pb center coincides with the peak of SiN film breakdown frequency at 900 degree-C, and the latter one of E’ center and K center coincides with the tendency of increasing Qbd frequency at more than 1000 degree-C. Figure 1

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39

Chen, Xi, Anyong Hu, Jianhao Gong i Jungang Miao. "Ka Band Low Channel Mutual Coupling Integrated Packaged Phased Array Receiver Front-End for Passive Millimeter-Wave Imaging". Micromachines 14, nr 4 (15.04.2023): 859. http://dx.doi.org/10.3390/mi14040859.

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This paper presents a Ka band eight-channel integrated packaged phased array receiver front-end for a passive millimeter-wave imaging system. Since multiple receiving channels are integrated in a given package, the mutual coupling issue affecting the channel will deteriorate imaging quality. Therefore, in this study, the influence of channel mutual coupling on the system array pattern and amplitude phase error is analyzed, and the design requirements are proposed according to the results. During the design implementation, the coupling paths are discussed, and passive circuits in the path are modeled and designed to reduce the level of channel mutual coupling and spatial radiation. Finally, an accurate coupling measurement method for a multi-channel integrated phased array receiver is proposed. The receiver front-end achieves a 28~31 dB single channel gain, a 3.6 dB noise figure, less than −47 dB of channel mutual coupling. Furthermore, the array pattern of the two-dimensional 1024 channel system composed of the front end of the receiver is consistent with the simulation, and the receiver’s performance is verified by a human-body-imaging experiment. The proposed coupling analysis, design, and measurement methods are also applicable to other multi-channel integrated packaged devices.

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Craton, Michael Thomas, Xenofon Konstantinou, John D. Albrecht, Premjeet Chahal i John Papapolymerou. "Additive Manufacturing of a W-Band System-on-Package". IEEE Transactions on Microwave Theory and Techniques 69, nr 9 (wrzesień 2021): 4191–98. http://dx.doi.org/10.1109/tmtt.2021.3076066.

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Baras, Torben. "Packaged X-band filter with optimized interconnects [Technical Committee]". IEEE Microwave Magazine 10, nr 1 (luty 2009): 146–50. http://dx.doi.org/10.1109/mmm.2008.930752.

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42

Tong, Ziqiang, Alexander Fischer, Andreas Stelzer i Linus Maurer. "Radiation Performance Enhancement of E-Band Antenna in Package". IEEE Transactions on Components, Packaging and Manufacturing Technology 3, nr 11 (listopad 2013): 1953–59. http://dx.doi.org/10.1109/tcpmt.2013.2272039.

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43

Alhenawy, Mahmoud, i Martin Schneider. "Antenna-in-package (AiP) in mm-wave band – ERRATUM". International Journal of Microwave and Wireless Technologies 6, nr 5 (10.03.2014): 542. http://dx.doi.org/10.1017/s1759078714000233.

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Younkyu Chung, Chun-Tung Cheung, M. P. DeLisio i D. B. Rutledge. "W-band waveguide-packaged InP HEMT reflection grid amplifier". IEEE Microwave and Wireless Components Letters 16, nr 6 (czerwiec 2006): 324–26. http://dx.doi.org/10.1109/lmwc.2006.875629.

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Dorogov, A. Yu, i A. I. Yashin. "SOFTWARE PACKAGE FOR MODELING HF-BAND PACKET RADIO NETWORKS". H&ES Research 12, nr 6 (2020): 26–37. http://dx.doi.org/10.36724/2409-5419-2020-12-6-26-37.

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It is noted that the complexity and constant variability of the ionosphere structure, the presence of many factors affecting the propagation of radio waves in such an environment, as well as the complex topology of communication networks lead to the need the computer modeling of data transmission in HF-band networks. The existing models of representation of ionospheric processes and digital radio channels are described. It is shown that to solve the problems of designing a radio data transmission network, complex modeling is necessary, taking into account the network topology, signal propagation losses in the radio channel, noise level, type of digital modulation, and radio forecast of communication conditions. In this paper, we consider a modeling complex for packet radio networks of HF-band data transmission with changing communication conditions. The complex consists of a set of interacting models implemented in the Matlab software environment. The software model for predicting communication conditions complies with ITU-R recommendation P. 533–13 of the International Telecommunication Union (ITU). The description of the model for the "Point-to-point" and "Area" modes is given and the results of its application for calculating extended radio lines are shown. The initial data and system parameters of the model are described. A model of the HF-band digital radio channel is presented. The communications System Toolbox package, which is part of the Matlab software environment, is used for this modeling. The model's input and output data are described. A model of Ionospheric Wave Frequency Dispatcher service of the radio network has been developed. This model is intended for building a wave schedule for stable operation of HF radio lines in the network. The rules for building a two-frequency and multi-frequency wave schedule are described. A scheme for modeling the operation of a packet radio network under changing communication conditions is proposed. The complex allows you to evaluate the probabilistic and temporal characteristics of radio lines and zonal radio coverage depending on geographical coordinates, time, month, solar activity and selected system parameters for a period of up to one year. Examples of using the modeling complex are given. The purpose of this work is to formulate the problem of simulation of HF radio networks under changing communication conditions.

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Zhu, Bonan, Seán R. Kavanagh i David Scanlon. "easyunfold: A Python package for unfolding electronic band structures". Journal of Open Source Software 9, nr 93 (15.01.2024): 5974. http://dx.doi.org/10.21105/joss.05974.

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Ahmad, Zainab, Magaji Ismail, Alhassan Shuaibu i Bashiru K. Sodipo. "First principle study on the Structural and Electronic Properties of Lead-Free Double Halide Perovskite Cs2InSbCl6". Physics Access 03, nr 01 (2023): 50–54. http://dx.doi.org/10.47514/phyaccess.2023.3.1.008.

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The structural and electronic characteristics of Cs2InSbCl6 were investigated using first principle density functional theory (DFT) within local density approximation (LDA) and generalized gradient approximation (GGA) as implemented in the Quantum ESPRESSO package. A supercell with 40 atoms was used in carrying out the calculations, using the optimized lattice parameters of the Cs2InSbCl6 (a = b = c =11.342 Ǻ). The findings revealed that Cs2InSbCl6 is a direct band gap material with gaps of 0.74 eV and 0.99 eV for LDA/PZ and GGA/PBE respectively, in which the GGA/PBE gap shows consistency within the literature range. The calculated densities of states highlight the contributions of the constituent atoms within the valence and the conduction bands.

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48

Lubis, K., T. Putriani i E. H. Kardhinata. "Relationship analysis related to acid stress of some cornlines used in soil using SSR markings". IOP Conference Series: Earth and Environmental Science 977, nr 1 (1.06.2022): 012033. http://dx.doi.org/10.1088/1755-1315/977/1/012033.

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Abstract This research aims to characterize, identify and determine the kinship patterns and bands of genetic diversity in maize lines developed in acid soils from SSRmarkers. This research was carried out at the Molecular Genetics Laboratory, Faculty of Agriculture, Universitas Sumatera Utara, Medan, from March to July 2021. This study used 3 lines and 2 of F1 in corn. To determine band size with the UVITEC Cambridge Fire Reader and to calculate genetic similarity and formation, the group used the Multivariate Statistical Package (MVSP Ver. 3.2). The Research method is the molecular marker method with 3 SSR primers (Cams 358, Tms 7 and Tms 9) the results showed that 3 primers received bands with sizes in the range of 255582 bp. Based on PCOA analysis, there is one sample that dispensed, which equates to 102 713 × NEI 9008. Based on research, CLA 84 × NEI 9008, CLA 106, CLA 84, and NEI9008 are sensitive genotypes and 102 713 × NEI 9008 represent genotypes. tolerant toacid stress.

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Mikhailov, Aleksandr I., Evgeniy А. Ryabov i Sergey A. Sergeev. "Evaluation of the possibilities of 3D-printing for the making of waveguide photonic crystals". Physics of Wave Processes and Radio Systems 25, nr 3 (29.09.2022): 29–35. http://dx.doi.org/10.18469/1810-3189.2022.25.3.29-35.

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The paper considers the possibilities of 3D printing technology for the manufacture of X-band waveguide photonic crystals. The photonic crystals for an EIA WR-90 standard rectangular waveguide with a cross section of 22,86 10,16 mm2 in the X-band were designed and manufactured. Numerical modeling of the reflection characteristics of photonic crystals of several designs in the OpenEMS software package was carried out. Based on the simulation results, the best types of the structures were selected, which were manufactured using the physical modeling technique by the fusion method of PETG plastic. Experimental study of the manufactured layouts and comparison of the experimental data with the numerical simulation data were performed. The best types of manufactured models of waveguide photonic crystals showed transmittance and reflection drop in the corresponding frequency bands of the order of 1520 dB, which is acceptable for technical applications. The numerical modeling results are in good agreement with experiments, thus indicating the high efficiency and good control of the topology and dimensions of the manufactured photonic crystals structural elements in the used type of 3D printing technology.

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Caban-Martinez, Alberto, Katerina Santiago, Jeramy Baum, Emre Dikici, Natasha Shaefer Solle, Sylvia Daunert, Sapna Deo i Erin Kobetz. "O1D.2 Objective measurement of work-environment carcinogenic exposures in florida firefighters using silicone-based passive sampling wristbands". Occupational and Environmental Medicine 76, Suppl 1 (kwiecień 2019): A9.2—A9. http://dx.doi.org/10.1136/oem-2019-epi.24.

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Firefighters are likely to be exposed to many toxic chemicals in the performance of their work duties such as polycyclic aromatic hydrocarbons (PAHs). Chemical exposures may occur through dermal, oral, or inhalation pathways. Passive sampling devices are used to sequester organic molecules through passive diffusion and provide time-weighted averages of chemical concentrations. This pilot study uses silicone-based wristbands as a personal passive sampler to detect known carcinogens during a 24 hour work shift. Twenty-four wristbands were deployed across various fire services throughout South Florida. Prior to deployment, bands were cleaned using a standardized cleaning protocol to remove contamination and optimize the surface for absorption. Wristbands were then packaged in air-tight bags to prevent contamination. Wristbands were worn on fire service personnel and collected at the end of a 24 hour work shift. Chemical contaminants were then extracted from the wristband and analyzed for PAHs—identified using the EPA IRIS, California Proposition 65, and IRAC datasets— using gas chromatography-mass spectrometry. The average number of chemicals found across all wristbands (n=24) was 23 with 4 categorized as carcinogenic to humans (i.e., Benzo[b]fluoranthene, Benzo[j]fluoranthene, Chrysene, and Naphthalene). All bands had at least one PAH present, specifically, 87.5% contained Benzo[b]fluoranthene (mean=5.23 ng/band), 50% contained Benzo[j]fluoranthene (mean=2.05 ng/band), 79.2% contained Chrysene (mean=9.55 ng/band), and 100% contained Napthalene (mean=176.53 ng/band). Actual types of exposure compounds is likely to be larger than the observed data as the group of PAHs detected was limited to three existing datasets. Silicone-based wristbands are feasible to use within the fire service to detect and characterize ambient hazardous chemical compounds. These personal self-samplers used during a 24 hour collection period identified various PAHs in the firefighter work environment. Objective measures of harmful chemical exposures in the fire service should be monitored with a comprehensive surveillance system that includes personal sampler devices.

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