- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Three-Dimensional Scanning Hall Probe Microscopy for Final Stage of Crack Growth of Chromium Molybdenum Steel SCM440
摘要： Crack propagation around the stress concentration area causes fatigue failure. Non-destructive method is necessary for monitoring structure fatigue before destruction. We focused on a magnetic non-destructive evaluation method for crack growth. In order to understand the relation between crack propagation and changes in magnetic flux density, we observed the position of the positive and negative magnetic flux density distributions around the crack of tool steel (SCM440) plate using a scanning Hall probe microscope (SHPM). We found that the vertical component of the three-dimensional magnetic flux density moved as the crack growth. Furthermore, the magnetic component which is parallel to the tensile stress appeared just before destruction of the specimen.
关键词： Crack propagation,Scanning Hall probe microscope,Magnetic flux density
更新于2025-09-23 15:22:29
-
Growth and physical properties of Ce(O,F)Sb(S,Se)2 single crystals with site-selected chalcogen atoms
摘要： Ce(O,F)Sb(S,Se)2 single crystals were successfully grown using a CsCl/KCl ?ux method. The obtained crystals have a plate-like shape with the typical size of 1–2 mm and well-developed ab-plane, which enables X-ray single crystal structural analysis. The Ce(O,F)Sb(S,Se)2 crystallizes in a monoclinic space group, P21/m, with lattice parameters of a = 4.121(7) ?, b = 4.109(7) ?, c = 13.233(15) ?, β = 97.94(7) °. It is composed of alternate stacking of Ce-(O,F) and Sb-SSe layers, and the Sb-SSe layer includes selective occupation of Se atoms in its in-plane site. The valence state of Ce is estimated to be Ce3+ by X-ray absorption ?ne spectroscopy analysis. The single crystals show an insulating behavior, and a magnetic ordering around 6 K.
关键词： E. Photoemission spectroscopy,B. Flux growth,D. Topological insulator,A. Layered mixed-anion compounds
更新于2025-09-23 15:22:29
-
New Dynamic Photo-Electro-Thermal Modeling of Light-Emitting Diodes with Phosphor Coating as Light Converter
摘要： Phosphor-coated light-emitting diode (PC-LED) is the dominant LED technology for public lighting. This paper presents a comprehensive theory for analyzing and modeling phosphor coating in white light-emitting diodes (LEDs) as a dynamic light converter. The new PC-LED model not only obeys the traditional diode equation, it includes the energy-storage and transient effects of the phosphor coating. Major control variables include energy storage in and the luminous flux from the phosphor coating. This new model enables the dynamic variations of luminous flux and energy storage and power loss in phosphor-coating to be accurately predicted. Part-1 of this paper provides the details of the theory and analysis leading to the new PC-LED model under the framework of the photo-electro-thermal theory. Details of the model parameter determination, model setup and experimental verification are included in Part-2. The model offers the important power loss equation of the phosphor coating which highlights the factors affecting the heat loss and the coating’s blackening effects. This equation can be used by engineers to design LED drivers in order to reduce the coating temperature and the blackening effects and to prolong LED lifetime.
关键词： Phosphor-coated light-emitting diodes (PC-LED),flux capacitor,light converter.,photo-electro-thermal (PET) theory,dynamic model of PC-LED
更新于2025-09-23 15:22:29
-
HIFiRE-5 Boundary-Layer Transition Measured in a Mach-6 Quiet Tunnel with Infrared Thermography
摘要： The principal goal of the Hypersonic International Flight Research Experimentation (HIFiRE) flight 5 is to measure hypersonic boundary-layer transition on a three-dimensional body. This paper presents measurements of heat flux and boundary-layer transition in the Boeing/U.S. Air Force Office of Scientific Research Mach-6 Quiet Tunnel. This facility has been developed to provide quiet flow at high Reynolds number, with low noise levels comparable to flight. Previously, the global heat flux and location of the transition front were measured with temperature-sensitive paint (TSP). A new HIFiRE-5 model was built with a polyether ether ketone shell, which is suitable for infrared–thermographic heat-flux measurements. Quiet-flow tests at Reynolds numbers of 8–12 ? 106∕m and zero angle of attack indicate a centerline transition location within 4% of the earlier TSP results, on the order of the uncertainty of the two techniques. This good agreement reinforces confidence in the earlier measurements and the new infrared-based technique. Examination of the off-centerline transition front indicates that the wavelength of stationary crossflow vortices is the same for both models and instrumentation techniques, although the streaks do not coincide precisely.
关键词： crossflow vortices,infrared thermography,Mach-6 quiet tunnel,boundary-layer transition,HIFiRE-5,heat flux
更新于2025-09-23 15:22:29
-
Real-time retrieval of transient heat flux on the surface of participating medium by using the EKF-RLSE technique
摘要： A hybrid algorithm of extended Kalman filtering and recursive least-square estimator (EKF-RLSE) is developed to solve the nonlinear inverse heat conduction-radiation problems in participating medium. By measuring the time-resolved temperature signals from a thermocouple installed on the other boundary of the participating medium, the proposed EKF-RLSE algorithm can realize real-time retrieval of the time-varying heat flux on the medium surface. The influence factors of the sampling interval, measurement and process covariance, forgetting factor, and medium thickness on the reconstruction accuracy and stability of the EKF-RLSE are investigated by numerical experiments. All the estimated results show that the present algorithm is robust and accurate in real-time estimating transient heat flux. If the nonlinear coupled conduction and radiation heat transfer problems is regard as the linear problems, the unknown time-dependent heat flux predicted by the KF-RLSE are also illustrated in this work.
关键词： Participating medium,Kalman filtering,Inverse nonlinear conduction-radiation,Time-varying heat flux,Recursive least squares estimator
更新于2025-09-23 15:22:29
-
Energetic Ions during Plasma-Enhanced Atomic Layer Deposition and their Role in Tailoring Material Properties
摘要： Plasma-enhanced atomic layer deposition (PEALD) has obtained a prominent position in the synthesis of nanoscale films with precise growth control. Apart from the well-established contribution of highly reactive neutral radicals towards film growth in PEALD, the ions generated during plasma exposure can also play a significant role. In this work, we report on the measurements of ion energy and flux characteristics on grounded and biased substrates during plasma exposure to typically used for PEALD (O2, H2, N2) were measured in a commercial 200-mm remote inductively coupled plasma ALD system equipped with RF substrate biasing. IFEDFs were obtained using a gridded retarding field energy analyzer and the effect of varying ICP power, pressure and bias conditions on the ion energy and flux characteristics of the three reactive plasmas were investigated. The properties of three material examples – TiOx, HfNx and SiNx – deposited using these plasmas were investigated on the basis of the energy and flux parameters derived from IFEDFs. Material properties were analyzed in terms of the total ion energy dose delivered to a growing film in every ALD cycle, which is a product of the mean ion energy, total ion flux and plasma exposure time. The properties responded differently to the ion energy dose depending on whether it was controlled with RF substrate biasing where ion energy was enhanced, or without any biasing where plasma exposure time was increased. This indicated that material properties were influenced by whether or not ion energies exceeded energy barriers related to physical atom displacement or activation of ion-induced chemical reactions during PEALD. Furthermore, once ion energies were enhanced beyond these threshold barriers with RF substrate biasing, material properties became a function of both the enhanced ion energy and the duration for which the ion energy was enhanced during plasma exposure. These results have led to a better insight into the relation between energetic ions and the ensuing material properties, e.g., by providing energy maps of material properties in terms of the ion energy dose during PEALD. It serves to demonstrate how the measurement and control of ion energy and flux characteristics during PEALD can provide a platform for synthesizing nanoscale films with the desired material properties.
关键词： ion energy dose,ion energy flux,ion bombardment,atomic layer deposition,RFEA,thin film,substrate biasing,ion flux,ion energy control,retarding field energy analyzer,plasma ALD
更新于2025-09-23 15:21:21
-
[IEEE 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Trebic, Czech Republic (2018.9.18-2018.9.20)] 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Novel Method of Total Spectral Radiant Flux Standard Realization
摘要： Modern metrology of SSL sources requires a modified approach to future realization of reference standards. This is caused by the fact that traditional broad band and omni-directional light sources used are being replaced by high intensity sources with a specific directional light intensity distribution. At the same time the importance of LED lighting quality assurance is increasing as this new type of lighting is currently replacing traditional light sources in many applications. The specifics of an integrating sphere-spectroradiometer measurement system require the calibration with the use of a reference standard with known Spectral Radiant Flux Distribution, Luminous flux as well as the Luminous Intensity Distribution (LID) to compensate for the sphere system non-uniform reflectance properties. This way the accuracy of the sphere system calibration will allow to measure various types of LED products in conformance with the EN 13032-4:2015, LED lamps, modules and luminaires modules, lamps regardless of their spatial distribution properties. This paper will cover basic concepts and details of a novel method of Total Spectral Radiant Flux (TSRF) realization and description of a TSRF standard facility developed for the Russian National Metrology Institute – VNIIOFI, Moscow. The method (and the developed facility) is based on a goniospectroradiometer system traceable to a standard Black Body and allowing the calibration of a light source in terms of TSRF and additionally providing LID data of the source.
关键词： calibration,measurement,total spectral radiant flux
更新于2025-09-23 15:21:21
-
[IEEE 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - Trebic, Czech Republic (2018.9.18-2018.9.20)] 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4) - The Measurement Method of Light Distribution Emitted from Sports Facilities Using Unmanned Aerial Vehicles
摘要： The dynamic development of cities is associated with a significant increase in the luminance of architectural buildings, advertisements or usable spaces. Objects that emit a significant amount of luminous flux to the environment are also various types of sports buildings, such as city stadiums, football pitches or tennis courts. The need to protect the environment determinates the need to reduce and prevent the effect of light pollution. The article analyzes the possibilities of using unmanned aerial vehicles to assess light pollution by measuring the distribution of luminous flux emitted by sports facilities. The method of light measurement based on a goniometric system using unmanned aerial vehicles was presented and their positioning in three-dimensional space was taken into account. A method for controlling the photometric probe and calibrating the measurement system has been proposed.
关键词： luminous flux,light pollution,Unmanned Aerial Vehicles
更新于2025-09-23 15:21:21
-
Highly Enhanced Photocatalytic Water-splitting Activity of Gallium Zinc Oxynitride Derived from Flux-assisted Zn/Ga Layered Double Hydroxides
摘要： The Ga/Zn-oxynitride solid solution [(GaN)1-x(ZnO)x] is one of the promising visible-light harvesting photocatalysts for overall water-splitting. A series of (GaN)1-x(ZnO)x (0.11 ≤ x ≤ 0.33) are synthesized by calcining the carbonate-type Zn/Ga-LDH precursor with and without sodium carbonate flux at 850 oC for 8 - 14 h under a NH3 gas-flow. The solid solutions without flux are determined to be low in crystallinity but plate-like in morphology with preferred orientation could be observed. On the other hand, those with flux turn out to be better in crystallinity, and eventually exhibit significantly higher photocatalytic activity for overall water splitting under visible-light irradiation than those without flux. In addition, the bandgap energies can also be engineered from 2.57 eV to 2.72 eV by changing the synthetic parameter such as nitridation time. It is, therefore, suggested that the present new approach can offer new opportunities for designing the next generation photocatalytic systems.
关键词： Overall water splitting,Photocatalyst,Gallium Zinc Oxynitride,Layered double hydroxides,Flux
更新于2025-09-23 15:21:21
-
[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Multistage Interband Cascade Thermophotovoltaic Devices with ~0.2 eV Bandgap
摘要： Detection of defects in induction machine rotor bars for disassembled motors are required to evaluate machines considered for repair as well as fulfilling incremental quality assurance checks in the manufacture of new machines. Detection of rotor bar defects prior to motor assembly are critical in increasing repair efficiency and assuring the quality of newly manufactured machines. Many methods of detecting rotor bar defects in unassembled motors lack the sensitivity to find both major and minor defects in both cast and fabricated rotors along with additional deficiencies in quantifiable test results and arc-flash safety hazards. A process of direct magnetic field analysis can examine measurements from induced currents in a rotor separated from its stator yielding a high-resolution fingerprint of a rotor’s magnetic field. This process identifies both major and minor rotor bar defects in a repeatable and quantifiable manner appropriate for numerical evaluation without arc-flash safety hazards.
关键词： magnetic flux,ac motors,electromagnetic measurements,induction motors,rotors,AC machines
更新于2025-09-23 15:21:01