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[IEEE 2019 URSI International Symposium on Electromagnetic Theory (EMTS) - San Diego, CA, USA (2019.5.27-2019.5.31)] 2019 URSI International Symposium on Electromagnetic Theory (EMTS) - Modeling Metamaterial Element in Dielectric-filled Waveguide-fed Metasurface Antennas
摘要： We study the modeling of metamaterial elements etched into planar, dielectric-filled waveguides for metasurface antennas. Metamaterial elements in these devices are subwavelength-sized, resonant openings embedded in waveguide walls—that can be modeled as the electric and magnetic dipoles—and couple to waveguide modes and radiate into free space. Due to a dielectric filling the waveguide, the dipole moments representing the element can contribute unequally to the scattered fields into the waveguide and the radiated fields into free space. Such different dipole strengths need to be considered for analytic modeling of metasurfaces. In this work, we present a retrieval of dipole moments of a metamaterial element by applying the law of power conservation and demonstrate its utility in the analytic model for the metasurface antennas.
关键词： dielectric-filled waveguides,dipole moments,power conservation,metamaterial elements,metasurface antennas
更新于2025-09-12 10:27:22
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Rare-earth element doping in glass frit for improved performance in silicon solar cells
摘要： Glass frit plays an important role in the silver paste for silicon solar cells. In this work, we prepare glass frit doped with different rare-earth elements (Y, La, Sm, Er) and study how the doping element affects the performance of the solar cells. Solar cells with La-doped and Sm-doped glass frits show average conversion efficiencies higher than 17.5%, while solar cells with Y-doped or Er-doped frit show lower efficiencies. By analyzing the Raman spectra of the rare-earth doped glass frits, we find that the average coordination number of Te–O (NTe(cid:1)O) in the glass can be tuned by the rare-earth dopant. La or Sm doping leads to a moderate value of NTe(cid:1)O, which is believed to achieve a glass formation ability that optimizes the structure of the Ag–Si interface of the cell for the best performance.
关键词： rare-earth elements,glass frit,Solar cells,Raman spectra
更新于2025-09-12 10:27:22
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Regular Microstructured Elements for Intensification of Gas–Liquid Contacting Made by Selective Laser Melting
摘要： Additive manufacturing (AM) as a novel technique for generating complex geometries is attracting interest in R&D. Besides the vast opportunities in rapid prototyping and manufacturing, especially in the chemical industry, the extended possibilities of producing devices highly adapted to specific tasks are opening new avenues for process intensification and miniaturization. In this work 3D-structured components for fluidic devices manufactured by selective laser melting are presented. Fluid guiding elements (FGE) structured with precisely defined fluid passages in the submillimeter range for absorption processes were additively manufactured. The elements were characterized and evaluated for CO2 absorption in water and NaOH solution. In general, the FGE structures show enhanced gas?liquid mass transfer in CO2 absorption. The absorption coefficient kl for CO2 in water is in the same range as reported for microstructured falling film devices. This example demonstrates the opportunity of using AM to produce innovative fluidic devices.
关键词： Fluid guiding elements,Mass transfer,Additive manufacturing,Selective laser melting,CO2 absorption
更新于2025-09-12 10:27:22
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Optically controlled field effect transistors based on photochromic spiropyran and fullerene C60 films
摘要： Optically controlled organic field effect transistors containing a binary mixture of fullerene C60 (n-semiconductor) and spiropyran (photoresponsive conductivity modulator) as the active layer were designed and fabricated. The obtained transistors demonstrated higher transfer characteristics (source-drain current), charge carrier mobility in the active layer, and response rate to an external influence than the multilayer transistor (wherein these semiconductor and photo responsive material are in different layers), which makes them promising candidates for the design of optical memory elements.
关键词： Optically controlled field effect transistors,photochromic spiropyran,fullerene C60,optical memory elements
更新于2025-09-12 10:27:22
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Intermediate band solar cell materials through the doping of group-VA elements (N, P, As and Sb) in Cu <sub/>2</sub> ZnSiSe <sub/>4</sub>
摘要： The electronic structure and optical properties of group-VA (N, P, As, and Sb)-doped Cu2ZnSiSe4 alloys have been studied using a hybrid functional through density functional theory calculations. The minor lattice distortion and small formation energy indicate that synthesis of these alloys is highly possible in experiment. For each doped alloy, an isolated and partially filled intermediate band (IB) appears in its band structure. The doping-induced IB is mainly contributed by the s states of the doped group-VA atom and the p states of four neighboring Se atoms, and slightly by the d states of eight Cu atoms. The existence of an IB obviously enhances the absorption coefficient with two additional absorption peaks in the visible light range. For P, As and Sb-doped Cu2ZnSiSe4 alloys, not only the bandgap between the valence band maximum and the conduction band minimum but also the sub bandgap between the valence band maximum and the IB are very close to the optimal values for visible light absorption. Therefore, these alloys are recommended as good candidates for IB solar cell materials.
关键词： intermediate band solar cell,optical properties,Cu2ZnSiSe4,group-VA elements,density functional theory
更新于2025-09-11 14:15:04
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Applications of Laser-Induced Breakdown Spectroscopy for Soil Characterization, Part II: Review of Elemental Analysis and Soil Classification
摘要： In-field soil health assessments, including plant nutrients and toxic elements, are needed and could improve the sustainability of agriculture production. Among the available analytical techniques for these analyses, laser-induced breakdown spectroscopy (LIBS) has become one of the most promising techniques for real-time soil analysis at low cost and without the need of reagents. The first part of this two-part review (Part I, Villas-Boas et al., 2019) in this issue focused on the fundamentals of LIBS for soil analysis and its use for soil chemical and physical characterization. Our objectives in this review article (Part II) are to review (i) the main applications of LIBS in the determination of soil carbon (C), nutrients and toxic elements, spatial elemental mapping, and (ii) its use in soil classification. Traditional and more recent techniques will be compared to LIBS, considering their advantages and disadvantages. LIBS is a promising, versatile technique for detecting many elements in soil samples, requires little or no sample preparation, takes only a few seconds per sample, and has a low cost per sample compared to other techniques. However, overcoming matrix effects is a challenge for LIBS applications in soil analysis, since most studies are conducted with limited changes in the matrix. In spite of the limitation of matrix effects, a typical LIBS system has a limit of detection of 0.3, 0.6, 4, 7, 10, 18, 46, and 89 mg kg-1 for Mo, Cu, Mg, Mn, Fe, Zn, K, and Ca, respectively. LIBS holds potential for real-time in-field spatial elemental analysis of soils and practical applications in precision farming with proper calibration. This could lead to immediate diagnoses of contaminated soil and inefficient nutrient supplies and facilitate well-informed soil management, increasing agricultural production while minimizing environmental impacts.
关键词： soil contamination,soil fertility,rhizosphere,toxic elements,spatial elemental mapping,SOM,precision agriculture,Plant nutrients,soil carbon
更新于2025-09-11 14:15:04
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Stress distribution characteristics of the optical fiber with multiple stress elements
摘要： The stress field in an optical fiber with one circular stress element is calculated theoretically. The stress field distribution for any optical fiber with multiple stress elements is derived based on the superposition theorem and the integration method. As is shown in this paper, the stress field in the core or in the region near core can be expressed by a formula with sine or cosine function. This result is important to reveal the coupling characteristics of the stress induced optical fiber with multiple stress elements when it is spun by an appropriate spinning rate.
关键词： Optical fiber,Multiple stress elements,Integration method,Stress field,Superposition theorem
更新于2025-09-11 14:15:04
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[Laser Institute of America ICALEO? 2015: 34th International Congress on Laser Materials Processing, Laser Microprocessing and Nanomanufacturing - Atlanta, Georgia, USA (October 18–22, 2015)] International Congress on Applications of Lasers & Electro-Optics - Comparison between ps- and μs-laser radiation for drilling holes for force transmission elements in CFRP-preforms
摘要： Current lightweight strategies in automobile, aerospace and wind energy applications include composite structures consisting of metal and fiber reinforced plastics for minimum weight, maximum force transmission and high material efficiency. Therefore, economic and technological beneficial material processing for the integration of force transmission elements such as inserts are crucial for these high performance materials. Current state of the art of machining carbon fiber reinforced material is to drill or mill the work piece after the consolidation process. Conventional mechanical and water jet processes lead to high tool wear and often non-repairable defects in the work piece such as delamination, fiber pullout, cracks in matrix and fibers, and deformation. Laser processing of the consolidated material can prevent force induced defects but leads to degradation of the matrix and leaves freestanding fibers inside the drilling hole which can damage the protective surface of subsequently inserted force transmission elements. This is especially critical for lifetime and performance during operation of the structural part. One solution is to drill the so called preform, prior to the infusion process, insert force transmission elements and subsequently infuse the preform with resin. Ultra sonic excited cutting knifes are not applicable for cutting hole diameters of a few millimeters with high aspect ratios. Punching as well as water jet cutting drop out due to force induced interaction with the textile or necessity of a subsequent drying process. Laser material processing could be an adequate solution to circumvent the above mentioned issues. Within this work, non-crimp carbon fiber (NCF) layers are investigated regarding laser processing via ultra-short pulsed and microsecond (fiber laser) radiation. The influence of different process parameters such as scanning speed, repetition rate and laser power are being evaluated regarding geometrical and materialographical quality such as conicity, textile swelling and heat affected zone (HAZ). The temperature distribution during laser processing is important for the estimation of when and where the knitting yarn, which keeps the carbon fiber plies together, disintegrates. Without the knitting yarn swelling occurs which is not desired for subsequent process steps.
关键词： force transmission elements,CFRP-preforms,microsecond laser,ultra-short pulsed laser,laser drilling
更新于2025-09-11 14:15:04
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Levels of Trace Elements in the Aqueous Humor of Cataract Patients Measured by the Inductively Coupled Plasma Optical Emission Spectrometry
摘要： Trace elements play an important role in the pathogenesis of several serious ophthalmological disorders, such as glaucoma, age-related macular degeneration (AMD), diabetic retinopathy, cataract, etc. This study aimed to measure alterations of chemical elements’ (67) levels in the aqueous humor of patients undergoing cataract surgery. The pilot study included 115 patients, (age 74 ± 7.27, female 64.35%, male 35.65%). The aqueous levels of elements were measured by the use of the inductively coupled plasma optical emission spectrometry (ICP-OES), quality controlled with certified standards. The classification of elements based on their concentration was achieved by hierarchical cluster analysis. This is the first screening study that quantifies over 60 elements which are present in the fluid from the anterior chamber of the eye of cataract patients. The obtained results can be suitable for understanding and identifying the causes that may play a role in the initiation and progression of lens opacity.
关键词： ICP-OES,the aqueous humor,trace elements,cataract
更新于2025-09-11 14:15:04
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Coherent Ray Tracing Simulation Of Non-Imaging Laser Beam Shaping With Multi-Aperture Elements
摘要： The application of laser light sources for illumination tasks like in mask aligner lithography relies on non-imaging optical systems with multi-aperture elements for beam shaping. When simulating such systems, the traditional approach is to separate the beam-shaping part (incoherent simulation) from dealing with coherence properties of the illuminating laser light source (diffraction theory with statistical treatment). We present an approach using Gaussian beam decomposition to include coherence simulation into ray tracing, combining these two parts, to get a complete picture in one simulation. We discuss source definition for such simulations, and verify our assumptions on a well-known system. We then apply our approach to an imaging beam shaping setup with microoptical multi-aperture elements. We compare the simulation to measurements of a similar beam-shaping setup with a 193 nm continuous-wave laser in a mask-aligner configuration.
关键词： Gaussian beam decomposition,laser beam shaping,mask aligner lithography,coherent ray tracing,multi-aperture elements
更新于2025-09-11 14:15:04