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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Where should beam down heliostat central rays intersect the final optical element axis?
摘要： A beam down solar system is adjusted to maximize the power collected through a final optical element concentrator. The power reaching the outlet of the final optical element is studied as a function of the reflectivity of its facets, and the height of the central ray convergence point of the beam down central reflector. A configuration that maximizes the energy fed to the solar receiver during the experimental campaign of the CSPonD Demo project is chosen and implemented at the beam down installation at the Masdar Institute Solar Platform.
关键词： final optical element,CSPonD Demo project,solar receiver,central ray convergence point,beam down solar system
更新于2025-09-04 15:30:14
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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Particle swarm optimization of the layout of a heliostat field
摘要： We present a new solar field layout optimization method that combines the Particle Swarm Optimization (PSO) algorithm with the parallelization power of the Graphical Processing Units (GPU). This new approach enables central receiver system designers to obtain very quickly an optimized field layout that take accurately into account all the optical losses (cosine effect, shadowing, blocking, atmospheric attenuation, and spillage). This is achieved by using a very fast implementation of a ray-tracing engine to compute the fitness objective (the annual performance of the field) that leverage the power of the parallel architecture of the GPUs. Initial results of the software on a couple of case studies are presented. These results demonstrate that solar field efficiency improvement is attainable with the proposed technique.
关键词： GPU,Heliostat Field,Ray-tracing,Solar Field Layout,Particle Swarm Optimization
更新于2025-09-04 15:30:14
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Towards simulation at picometer-scale resolution: Revisiting inversion domain boundaries in GaN
摘要： Motivated by recent high resolution results on the inversion domain boundaries (IDB) in gallium nitride, we re?ne by ab initio DFT calculations the well established atomic model IDB? derived by Northrup et al. This allows us to recover these experimental results obtained by coherent x-ray diffraction and showing small additional shifts of the polarity domains, in particular 8 pm shift along the hexagonal direction. The in?uence of boundary conditions and electrostatic ?elds (IDB-IDB and IDB-surface interactions) on the results and the existence of metastable solutions is carefully discussed to stress the accuracy of the method. These results demonstrate a cross-talk between advanced characterization tools and state-of-the-art ab initio calculations that opens perspectives for the structural analysis of defects in the picometer range.
关键词： picometer resolution,ab initio DFT calculations,coherent x-ray diffraction,gallium nitride,inversion domain boundaries
更新于2025-09-04 15:30:14
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Structural characteristics of m-plane AlN substrates and homoepitaxial films
摘要： Homoepitaxial non-polar AlN films were realized on m-plane (1010)-oriented AlN single crystals by metalorganic chemical vapor deposition (MOCVD). The microstructural properties of m-plane AlN substrates and homoepitaxial films were assessed by means of atomic force microscopy and high resolution x-ray diffraction characterization. Results indicated that both m-plane AlN substrates and films possessed exceptional structural quality, with some anisotropic mosaic distributions due to the quasi-bulk nature of the non-polar single crystals. An increase in the MOCVD growth temperature was noted to minimize the degree of inherited mosaic anisotropy without altering the m-plane AlN film growth rate, indicating that high temperature growth is critical to produce optimal film crystallinity. A dramatic change in the film surface morphology from heavily faceted “slate-like” features to monolayer steps was observed as the growth temperature was increased. The “slate-like” surface morphology produced low intensity cross-streaks in symmetric (1010) reciprocal space maps, tilted about 18° away from the (1010) crystal truncation rod. The orientation of these diffuse streaks corresponds to the physical alignment of the slates with respect to the substrate surface normal. X-ray line scans and defect-selective reciprocal space mapping confirmed that these low intensity streaks are solely dependent on this peculiar surface structure produced at low MOCVD growth temperatures and unrelated to basal plane stacking faults or other extended defects. All observations confirm that high quality III-nitride epitaxial structures on m-plane AlN substrates are attainable with controllable MOCVD growth processes, as demanded for future high performing AlN-based non-polar devices.
关键词： Characterization,Metalorganic chemical vapor deposition,High resolution x-ray diffraction,Surface structure,Nitrides,Crystal structure
更新于2025-09-04 15:30:14
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Molecular structures, DFT studies and their photophysical properties in solution and solid state. Microwave-assisted multicomponent synthesis of organotin bearing Schiff bases
摘要： A couple of luminescent organotin compounds derivated from ligands-ONO were obtained by multicomponent microwave assisted synthesis in short time (15 min) and good yields: ((E)-8, 8-8-diphenylbenzo[d] naphtho [1,2-h][1,3,6,2] dioxazastannonine (1) and (E)11, 13- di-tert-butyl, 8- diphenylbenzo [d] naphtho [1,2-h][1,3,6,2] dioxazastannonine (2)). Both compounds were fully characterized by NMR (1H, 13C, and 119Sn; 2D-NMR, HETCOR and COSY), UVeVis, IR, and high-resolution mass spectrometry. The X-ray structures of two complexes demonstrate that the tin atoms adopt a bipyramidal trigonal geometry. The 119Sn NMR chemical shifts of the tin atom in the complexes are also consistent with the presence of pentacoordinate tin centers. The photophysical properties in solution and solid state, DFT, and voltammetry the two complexes have been determined.
关键词： Fluorescence,X-ray,Schiff base,Organotin,Microwave assisted synthesis
更新于2025-09-04 15:30:14
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Photoluminescence Imaging for Buried Defects Detection in Silicon: Assessment and Use-cases
摘要： In this work, the innovative photoluminescence imaging technique is described for applications to buried defect detection in silicon devices. The validity of this emerging technique is first assessed in comparison with well-established characterization techniques (defect selective etching of silicon, X-Ray diffraction topography, cross-sectional transmission electron microscopy imaging and photoluminescence spectroscopy). The paper then describes specific applications illustrating the use of the photoluminescence imaging technique for common processes of the CMOS semiconductor industry. The benefit of this fast, high resolution and non-destructive technique is demonstrated: this includes industrial use of the technique for in-line production control on product wafers.
关键词： photoluminescence imaging,dislocations,non-visual defects,X-Ray diffraction topography,photoluminescence spectroscopy,buried defects
更新于2025-09-04 15:30:14
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Recognition of incorrect assembly of internal components by X-ray CT and deep learning
摘要： It is important to make sure that all components of a complex product are assembled correctly. Because in many cases, some components are enclosed in an opaque shell, x-ray imaging is currently used to extract their characteristics and match prior-known ones. However, x-ray imaging is not very robust in recognition of incorrect assembly of internal components, because some of them may overlap. To solve this problem, we propose a new method to detect internal component assembly fault, by x-ray computed tomography (CT) and convolutional neural network (CNN). Multi-view imaging is implemented by mechanical rotation of a product in respect with an x-ray CT machine to capture multiple projection information on each internal component, and then the component can be recognized by making use of deep learning. A CNN model is trained to classify the internal components and give the coordinates of each component. Based on the CNN recognition results and the CT projection sinogram, a projection corresponding to a reference in a projection data set of a standard product can be found. By comparing and matching the locations of each component, transposition or dislocation can be recognized. Both simulation and experiment show that this new method can effectively identify incorrect assembly, missing assembly, transposition, and other problems, improving the product quality.
关键词： Projection sinogram,Assembly recognition,Convolution neural network (CNN),x-ray CT
更新于2025-09-04 15:30:14
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Impact of Magnesium substitution in Nickel ferrite: Optical and Electrochemical studies
摘要： Magnesium doped Ni ferrite nanoparticle (Ni1-xMgxFe2O4) has been synthesized by sol-gel combustion method and it has been analyzed using XRD, UV, FTIR and electrochemical charge-discharge studies. The observed XRD result confirms the nanostructure and it ranges from 23 to 28 nm. Furthermore, band gap energy values and functional group elements have been observed by UV and FTIR, respectively. The lattice constant values varies slightly with respect to magnesium concentration. The band gap energy values increase at the calcination temperature of 500oC as 0.85, 1.15, 1.2, and 1.45 eV and it decreases when it was calcined at 900oC as 1.3, 1.25, 1.15, 1.1 eV for x =0.25, 0.5, 0.75, 1, respectively. The voltage profiles of Ni1-xMgxFe2O4 nanoparticle electrodes show the discharge and charge capacities of 1021 and 718 mAh/g at 500oC and 1099 and 747 mAh/g at 900oC, respectively. The high reversible capacities for the Mg doped Ni ferrite nanoparticle electrodes are confirmed as anode materials for Li ion batteries.
关键词： X-ray diffraction,electrochemical study,Nanoferrite,bandgap energy
更新于2025-09-04 15:30:14
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Three-strip microchannel plate gated x-ray framing camera
摘要： A microchannel plate (MCP) gated x-ray framing camera with three-strip is reported. The diameter of the MCP is 56 mm and the width of each microstrip line cathode deposited on the MCP is 8 mm. While the microstrip line cathode is driven by a gating electrical pulse with width of 200 ps and amplitude of ?1.9 kV overlapped with a ?200 V DC bias, the measured temporal resolution is about 68 ps. Furthermore, the gain uniformity of the microstrip line cathode is measured showing that there is a 3.6× drop in gain along the pulse propagation direction, whereas the variations in the gain transverse to the pulse propagation direction are within 10%.
关键词： X-ray detector,Temporal resolution,Framing camera,Gain uniformity
更新于2025-09-04 15:30:14
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Cr/C Reflective Multilayer for Wavelength of 44.8 ?
摘要： The working wavelength of Ni-like, Ta soft X-ray laser is 44.8 ?, just near the “water window.” High re?ection multilayers are required for this kind of laser in China. In this work, we design and fabricate carbon-based multilayer re?ective samples. The Cr/C multilayer was selected from proposed candidates such as Co/C, Ni/C, and CoCr/C material combinations. The period thickness is only 22.6 ?. Cr/C multilayers were deposited by the magnetron sputtering method. Multilayers with bi-layer numbers of 150, 200, 250 and 300 were deposited onto super polished silicon wafers. All multilayers have been characterized by grazing incidence X-ray re?ectance (GIXRR). Then, near-normal incidence re?ectance measurements were performed at beamline 3W1B, Beijing synchrotron radiation (BSRF). The highest re?ectance of 13.2% is achieved with the bi-layer number of 300. Transmission electron microscopy measurements also clearly show the sharp Cr–C interfaces in the multilayer.
关键词： Multilayer,Soft X-ray Laser,Re?ectance,Magnetron Sputtering,Synchrotron Radiation
更新于2025-09-04 15:30:14