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- 实验方案
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Effect of the Orientation Schemes of the Energy Collection Element on the Optical Performance of a Parabolic Trough Concentrating Collector
摘要： While the circular shape is currently the proven optimum design of the energy collection element (ECE) of a parabolic trough collector, that is yet to be confirmed for parabolic trough concentrating collectors (PTCCs) like trough concentrating photovoltaic collectors and hybrid photovoltaic/thermal collectors. Orientation scheme of the ECE is expected to have significant effect on the optical performance including the irradiance distribution around the ECE and the optical efficiency, and therefore, on the overall energy performance of the PTCC. However, little progress addressing this issue has been reported in the literature. In this study, a thorough investigation has been conducted to determine the effect of the orientation schemes of ECE on the optical performance of a PTCC applying a state-of-the-art Monte Carlo ray tracing (MCRT) technique. The orientation schemes considered are a flat rectangular target and a hollow circular, semi-circular, triangular, inverted triangular, rectangular and rectangle on semi-circle (RSc). The effect of ECE defocus, Sun tracking error and trough rim angle on the optical performance is also investigated. The MCRT study reveals that the ECE orientation schemes with a curved surface at the trough end showed much higher optical efficiency than those with a linear surface under ideal conditions. ECEs among the linear surface group, the inverted triangular orientation exhibited the highest optical efficiency, whereas the flat and triangular ones exhibited the lowest optical efficiency, and the rectangular one was in between them. In the event of defocus and tracking errors, a significant portion of the concentrated light was observed to be intercepted by the surfaces of the rectangular and RSc ECEs that are perpendicular to the trough aperture. This is an extended version of a published work by the current authors, which will help to design an optically efficient ECE for a parabolic trough concentrating collector.
关键词： optical efficiency,optical performance,concentrating solar power,parabolic trough concentrating collector,irradiance distribution,Monte Carlo ray tracing
更新于2025-09-23 15:23:52
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Study on the Statistical Errors in X-Ray Stress Measurement with Two-Dimensional Detector
摘要： The sin2 ψ method [1] is conventionally used well as how to measure non-destructively the residual strain and stress states of polycrystalline materials by X-ray diffraction. In the conventional method, there are D?lle-Hauk method [2] and Winholz-Cohen least squares analysis [3] as the determinations of the strain and stress states for limiting the influence of measurement errors. Many researches are made about the statistical error in those methods. In recent years, use of the X-ray stress measurements with two-dimensional detector from the conventional method is spreading. One of the measurements is called the cos α method. The measurement errors have attracted a great deal of attention for users as the spreads. Therefore, the basic equations and determinations of the strain and stress states are examined. The confidence intervals of measured stress by the cos α method. The research and development is performed for the the cos α method which took the influence of measurement errors into consideration.
关键词： Cos α method,Non-destructive inspection,Statistical errors,Two-dimensional detector,X-ray stress measurement,internal stress
更新于2025-09-23 15:23:52
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Signal enhancement in laser diode thermal desorption-triple quadrupole mass spectrometry analysis using microwell surface coatings
摘要： Laser diode thermal desorption (LDTD) is an ionization source usually coupled to triple quadrupole mass spectrometry (QqQMS) and specifically designed for laboratories requiring high-throughput analysis. It has been observed that surface coatings on LDTD microwell plates can improve the sensitivity of the analysis of small polar molecules. The objective of the present study is to understand and quantify the effect of microwell surface coatings on signal intensity of small organic molecules of clinical, environmental and forensic interest. Experiments showed that the peak areas of diclofenac, chloramphenicol, salicylic acid and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol obtained by LDTD-QqQMS increased by up to 3 orders of magnitude when using microwells coated with ethylenediaminetetraacetic acid (EDTA). Tests with different chelating agents and polytetrafluoroethylene as microwell surface coatings showed that nitrilotriacetic acid gave significantly higher peak areas for five out of the nine compounds that showed signal enhancement using chelating agents as coatings. Scanning electron microscopy studies of EDTA-coated and uncoated microwells showed that analytes deposited in the former formed more uniform and thinner films than in the latter. The enhancement effect of surface coatings in LDTD-QqQMS was explained mainly by the formation of homogenous and thinner layers of nanocrystals of analytes that are easier to desorb thermally than the layers formed when the analytes dry in direct contact with the bare stainless steel surface. Chemisorption of some analytes to the stainless steel surface of the microwell plate appeared to be a minor factor. Surface coatings widen the number of compounds analyzable by LDTD-QqQMS and can also improve sensitivity and limits of detection.
关键词： pharmaceuticals,high-throughput,hormones,pesticides,x-ray photoelectron spectroscopy,scanning electron microscopy,stainless steel,small organic molecules,chelating agents
更新于2025-09-23 15:23:52
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Achievable noise performance of spectroscopic prototype DEPFET detectors
摘要： A new generation of spectroscopic X-ray DEPFET detectors has been produced in the course of the detector development for the Wide Field Imager (WFI) of Athena. These devices served to perform a detailed analysis of the noise composition, which was enabled by the development of appropriate test algorithms. A result of the analysis is the distinction of different components, which sum up to the total noise. In particular the contribution of shot noise, white noise and 1/f noise to the readout noise is determined as well as the signal noise caused by the generation of charge carriers. The resulting parametrization enables the adaptation and optimization of operation modes to given purposes. The studied prototype detectors included 64×64 pixels with a linear gate design and provided an excellent noise, below 1.6 e?ENC at a readout time faster than 10 μs/pixel and a temperature of -80 ?C in rolling-shutter operation. This performance is enabled by an extended signal integration time. A further noise reduction is prevented by the signal noise, caused by charge carrier generation. In order to demonstrate the low noise properties of the DEPFET transistor, the measurement conditions were adapted and a noise of 0.95 e?ENC was measured at the expense of the sensor size — by operating only parts of the sensor in window mode — and dynamic range — by using the Al Kα line at about 1.49 keV for calibration.
关键词： Imaging spectroscopy,Solid state detectors,Instrumental noise,X-ray detectors and telescopes
更新于2025-09-23 15:23:52
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Using a commercial mini-X-ray source for calibrating Bragg crystals
摘要： In this paper we describe a procedure for calibration of Bragg crystals used for X-ray spectroscopy of laser plasmas. The method uses a relatively inexpensive commercially available X-ray source. By using the source to pump a metallic foil such as vanadium or titanium we were able to create a K-α emission source with minimal background radiation outside the desired photon energy. By using photon counting techniques with a CCD detector we were able to get absolute calibrations of curved and flat Bragg crystals in the 4–5 keV region. An important advantage of our method is that absolute calibration was not necessary either for the commercial source or the detector.
关键词： X-ray detectors and telescopes,spectroscopy and imaging,Plasma diagnostics - interferometry
更新于2025-09-23 15:23:52
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Spectroscopic DEPFETs at high frame rates using window mode
摘要： An active pixel sensor like an array of DEPFET (DEpleted P-channel Field Effect Transistor) pixels allows for very flexible operation modes and an adaptability of the sensor design to the specific needs of the scientific instrument objectives. For a very high time resolution at the order of one microsecond, a full parallel readout of all pixels is required. Every readout node needs to be connected to readout electronics separately. Furthermore, to preserve a good spectroscopic performance, the integration of a storage functionality into each pixel prevents the influence of events occurring during the readout process and provoking an incorrect energy information. The energy of such events is detected incorrectly and is not falsifiable with a subsequent analysis. An active pixel sensor based on a DEPFET with internal storage and wired for full parallel readout is in production and will be available for testing in the future. Alternatively, the ability of an active pixel sensor to be read out in window (region-of-interest readout) mode allows for the investigation of the behavior at high frame rates at the order of 100 kHz for DEPFET devices with and without storage functionality.
关键词： Imaging spectroscopy,Solid state detectors,X-ray detectors and telescopes
更新于2025-09-23 15:23:52
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A new non-centrosymmetric Chlorobismuthate(III) hybrid material: Crystal structure, optical properties and antibacterial study
摘要： As part of our interest in organic-inorganic metallate complexes, we had prepared a novel non-centrosymmetric chlorobismuthate (III) compound with the chemical formula (C6H7NCl)3 [BiCl6]$H2O, by slow evaporation method at room temperature. It was characterized by single crystal X-ray diffraction (SCXRD), X-ray powder diffraction (PXRD), spectroscopic measurements, thermal study, Hirshfeld surface analysis, DFT investigation, and antimicrobial activity. A preliminary SCXRD structural analysis revealed that the compound crystallizes in the Orthorhombic system (P212121 space group) with the following unit cell parameters a ? 7.3432 (1) ?, b ? 13.8257 (2) ? and c ? 28.2140 (5) ? with Z ? 4 and V ? 2864.42 (8) ?3. The examination of the structure shows that its atomic arrangement can be described as inorganic [BiCl6]3- units isolated from each other by the organic cations and the co-crystallized water molecules. The cohesion between these entities is performed via the NeH/Cl, NeH/O, CeH/O, CeH/Cl, and OeH/Cl hydrogen bonding interactions between the 4-dichloroanilinium cations, the [BiCl6]3- anions and water molecules forming a 3D network. The Hirshfeld surface calculation was conducted to investigate: intermolecular interactions, associated 2D ?ngerprint plots, and enrichment ratio, indicating the relative contribution of these interactions in the crystal structure quantitatively. Thermal analysis reveals the decomposition of the compound at 180 (cid:2)C. The quantum mechanical calculations such as geometry optimization, vibrational frequencies, simulated UVeVisible spectrum, FMOs analysis were made together with the experimental studies. Furthermore, the new synthesized compound was screened for its antibacterial activity. Results revealed that it has the most effective activity against all the tested bacteria compared to the amine alone and to the BiOCl.
关键词： Hirshfeld surface analysis,Hybrid material,DFT calculations,Hexachlorobismuthate(III),X-ray diffraction,Antimicrobial activity
更新于2025-09-23 15:23:52
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Multi-label chest X-ray image classification via category-wise residual attention learning
摘要： This paper considers the problem of multi-label thorax disease classification on chest X-ray images. Identifying one or more pathologies from a chest X-ray image is often hindered by the pathologies unrelated to the targets. In this paper, we address the above problem by proposing a category-wise residual attention learning (CRAL) framework. CRAL predicts the presence of multiple pathologies in a class-specific attentive view. It aims to suppress the obstacles of irrelevant classes by endowing small weights to the corresponding feature representation. Meanwhile, the relevant features would be strengthened by assigning larger weights. Specifically, the proposed framework consists of two modules: feature embedding module and attention learning module. The feature embedding module learns high-level features with a convolutional neural network (CNN) while the attention learning module focuses on exploring the assignment scheme of different categories. The attention module can be flexibly integrated into any feature embedding networks with end-to-end training. The comprehensive experiments are conducted on the Chest X-ray14 dataset. CRAL yields the average AUC score of 0.816 which is a new state of the art.
关键词： Image classification,Chest X-ray,Convolutional neural network,Residual attention
更新于2025-09-23 15:23:52
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Effect of Oxygen on Thermal and Radiation Induced Chemistries in a Model Organotin Photoresist
摘要： Organotin photoresists have shown promise for next generation lithography due to their high extreme ultraviolet (EUV) absorption cross sections, their radiation sensitive chemistries, and their ability to enable high-resolution patterning. To better understand both temperature and radiation induced reaction mechanisms, we have studied a model EUV photoresist, which consists of a charge-neutral butyl-tin cluster. Temperature programmed desorption (TPD) showed very little outgassing of the butyl-tin resist in ultrahigh vacuum, and excellent thermal stability of the butyl groups. TPD results indicated that decomposition of the butyl-tin resist was first order with a fairly constant decomposition energy between 2.4 and 3.0 eV, which was determined by butyl group desorption. Electron stimulated desorption (ESD) showed that butyl groups were the primary decomposition product for electron kinetic energies expected during EUV exposures. XPS was performed before and after low energy electron exposure to evaluate the compositional and chemical changes in the butyl-tin resists after interaction with radiation. The effect of molecular oxygen during ESD experiments was evaluated and it was found to enhance butyl group desorption during exposure, and resulted in a significant increase in the ESD cross section by over 20%. These results provide mechanistic information that can be applied to organotin EUV photoresists, where a significant increase in photoresist sensitivity may be obtained by varying the ambient conditions during EUV exposures.
关键词： X-ray photoelectron spectroscopy,electron stimulated desorption,Extreme ultraviolet lithography,organotin photoresist,temperature programmed desorption
更新于2025-09-23 15:23:52
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Characterization of the morphology of titanium and titanium (IV) oxide nanolayers deposited on different substrates by application of grazing incidence X-ray diffraction and X-ray reflectometry techniques
摘要： X-ray diffraction (XRD), grazing incidence X-ray diffraction (GIXRD) and X-ray reflectometry (XRR) techniques were applied for analysis of titanium (Ti) and titanium (IV) oxide (TiO2) nanolayers with thickness of 25 nm, 50 nm and 75 nm deposited on silicon, quartz and BK7 glass substrates. The aim of studies was investigating the crystal structure and morphology of the nanolayers in dependence on the substrate type. The chemical phases of nanolayers and substrates were determined by using the XRD and GIXRD measurements. The benefits of applying low angle GIXRD and XRR analytical techniques, both for substrate and nanofilm analysis, is discussed based on theoretical calculations and simulations. Additional, analytical capabilities of the XRR technique to nanolayer and substrate morphology analysis are presented. Simulated XRR curves for titanium (Ti) and titanium (IV) oxide nanolayers are discussed depending on the substrate type as well as the substrate and nanolayer roughnesses. Experimental reflectometry curves are presented for all titanium and titanium (IV) oxide nanolayers deposited on the different substrates. As the result of the XRR analysis, the nanolayer thickness and roughness together with substrate roughness are estimated. The mean values of the Ti and TiO2 layer thickness and roughness are presented for all studied samples. The largest roughness, both for nanolayers and for substrates, is obtained for BK7 glass material. In the manuscript, sample properties, experimental setups and measurement conditions are presented in details.
关键词： Titanium nanolayers,Titanium (IV) oxide nanolayers,Layer ion modification,X-ray reflectometry,Grazing incidence X-ray diffraction,Silicon, quartz substrates
更新于2025-09-23 15:22:29