- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[Micro/Nano Technologies] Micro and Nano Fabrication Technology Volume 1 || Bonnet Polishing of Microstructured Surface
摘要： Microstructured surfaces have been adopted in various and wide applications. Different types of microstructures made of ductile materials can be generated by cutting process, for example, turning and milling with speci?ed diamond cutters. However, these processes generally are not capable to handle with hard and brittle materials which are called dif?cult-to-machine materials. Computer-controlled ultra-precision polishing with bonnet provides an enabling solution to generate microstructures due to its feasible in?uence function. With proper machining parameters, speci?ed shape of the tool in?uence function is hence obtained, and then with aid of tool path planning, microstructured surface topography is generated, especially for those dif?cult-to-machine materials. In this chapter, research work for generating microstructured surface by computer-controlled ultra-precision bonnet polishing is presented. The material removal characteris- tics and tool in?uence function of bonnet polishing are explained, and a multi- scale material removal model and a surface generation model were developed. Surface generation of microstructures by single precess polishing and swing precess polishing is explained in details. A series of simulation and real polishing experimental studies are undertaken based on a seven-axis ultra-precision freeform polishing machine. The generated microstructured surfaces with various patterns have been analyzed. The research results have demonstrated that the proposed bonnet polishing provides an enabling and effective approach for generating microstructured surfaces.
关键词： Modelling,Bonnet polishing,Ultra-precision machining,Dif?cult-to- machine material,Precess polishing,Surface generation,In?uence function,Computer controlled polishing,Microstructured surface,Multi-scale material removal,Simulation
更新于2025-09-23 15:21:01
-
A new parameterization of the UV irradiance altitude dependence for clear-sky conditions and its application in the on-line UV tool over Northern Eurasia
摘要： A new method for calculating the altitude UV dependence is proposed for different types of biologically active UV radiation (erythemally-weighted, vitamin-D-weighted and cataract-weighted types). We show that for the specified groups of parameters the altitude UV amplification (AUV) can be presented as a composite of independent contributions of UV amplification from different factors within a wide range of their changes with mean uncertainty of 1% and standard deviation of 3% compared with the exact model simulations with the same input parameters. The parameterization takes into account for the altitude dependence of molecular number density, ozone content, aerosol and spatial surface albedo. We also provide generalized altitude dependencies of the parameters for evaluating the AUV. The resulting comparison of the altitude UV effects using the proposed method shows a good agreement with the accurate 8-stream DISORT model simulations with correlation coefficient r>0.996. A satisfactory agreement was also obtained with the experimental UV data in mountain regions. Using this parameterization we analyzed the role of different geophysical parameters in UV variations with altitude. The decrease in molecular number density, especially at high altitudes, and the increase in surface albedo play the most significant role in the UV growth. Typical aerosol and ozone altitude UV effects do not exceed 10-20%. Using the proposed parameterization implemented in the on-line UV tool (http://momsu.ru/uv/) for Northern Eurasia over the PEEX domain we analyzed the altitude UV increase and its possible effects on human health considering different skin types and various open body fraction for January and April conditions in the Alpine region.
关键词： UV radiation,altitude dependence,RT modelling,cataract-weighted irradiance,erythemally-weighted irradiance,vitamin D-weighted irradiance,interactive UV-tool
更新于2025-09-23 15:21:01
-
Optical properties of metamorphic type-I InAs <sub/> 1? <i>x</i> </sub> Sb <sub/><i>x</i> </sub> /Al <sub/><i>y</i> ? </sub> In <sub/> 1? <i>y</i> ? </sub> As quantum wells grown on GaAs for the mid-infrared spectral range
摘要： We analyse the optical properties of InAs1?xSbx/Aly In1?y As quantum wells (QWs) grown by molecular beam epitaxy on relaxed Aly In1?y As metamorphic buffer layers (MBLs) using GaAs substrates. The use of Aly In1?y As MBLs allows for the growth of QWs having large type-I band offsets, and emission wavelengths >3 μm. Photoluminescence (PL) measurements for QWs having Sb compositions up to x = 10% demonstrate strong room temperature PL up to 3.4 μm, as well as enhancement of the PL intensity with increasing wavelength. To quantify the trends in the measured PL we calculate the QW spontaneous emission (SE), using a theoretical model based on an eight-band k·p Hamiltonian. The theoretical calculations, which are in good agreement with experiment, identify that the observed enhancement in PL intensity with increasing wavelength is associated with the impact of compressive strain on the QW valence band structure, which reduces the band edge density of states making more carriers available to undergo radiative recombination at fixed carrier density. Our results highlight the potential of type-I InAs1?xSbx/Aly In1?y As metamorphic QWs to address several limitations associated with existing heterostructures operating in the mid-infrared, establishing these novel heterostructures as a suitable platform for the development of light-emitting diodes and diode lasers.
关键词： light-emitting diode,k·p modelling,metamorphic heterostructure,mid-infrared,semiconductors,molecular beam epitaxy,photonics
更新于2025-09-23 15:19:57
-
Novel reconfiguration approach to reduce line losses of the photovoltaic array under various shading conditions
摘要： This paper presents a novel fixed reconfiguration scheme to reduce partial shading conditions in the Photovoltaic (PV) array. The proposed approach is based on Skyscraper (SS) technique, which implies that the physical location of the PV modules in the array is arranged using Skyscraper fashion so that it distributes the shading impacts across the array in order to increase energy yields. Various kinds of partial shading conditions have been taken into account to examine the effects on the proposed approach in 6×6 array. Further, the performance of the proposed arrangement is compared with the other existing array interconnections such as ”series-parallel (SP), total-cross-tied (TCT), bridge-link (BL), honey-comb (HC) and Arrow-SuDoKu (AS)” by obtaining the several parameters like ”global maximum power point (GMPP), the voltage at GMPP, fill-factor, shading losses, efficiency, and possible local peaks (PLP)”. In addition to this, a simple calculation is performed to evaluate the wiring losses for the proposed skyscraper arrangement. Lastly, the outcome of this paper demonstrates that the suggested skyscraper scheme reduces the loss of shading and increases the power production relative to the other array interconnections. Also, in comparison with the Arrow SuDoKu scheme, the proposed scheme is impacted by the minimum wiring loss.
关键词： Photovoltaic Modelling,PV array Interconnections,Static fixed reconfiguration
更新于2025-09-23 15:19:57
-
[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Investigating metal-semiconductor contacts in solar cells using magnetic field measurements
摘要： While solar cells and modules are already a mature technology in mass production, contacting schemes are constantly evolving. For example, multi busbar/multi wire contacting systems are currently being developed. During the development and the production of such technologies, it is critical to optimize and to systematically monitor their performance. In this paper, we find that different contacting fault types can be identified by inducing specific current flow patterns through the contacts of a single side of a solar cell and measuring the resultant 2D magnetic field image. Additionally, we explore the use of circuit network modelling in conjunction with these magnetic field images to gain further insights about the contacting schemes. Excellent agreement between circuit simulations and magnetic field measurements was achieved by combining different current flow patterns as demonstrated on a multi-wire contacted solar cell.
关键词： photovoltaic cells,circuit modelling,characterization,magnetic field measurements,SPICE
更新于2025-09-23 15:19:57
-
An Energy-Efficient 10-Gb/s CMOS Millimeter-Wave Transceiver With Direct-Modulation Digital Transmitter and I/Q Phase-Coupled Frequency Synthesizer
摘要： The paper presents a novel technique based on extension of a general mathematical method of transfinite interpolation to solve an actual problem in the context of a heterogeneous volume modelling area. It deals with time-dependent changes to the volumetric material properties (material density, colour, and others) as a transformation of the volumetric material distributions in space-time accompanying geometric shape transformations such as metamorphosis. The main idea is to represent the geometry of both objects by scalar fields with distance properties, to establish in a higher-dimensional space a time gap during which the geometric transformation takes place, and to use these scalar fields to apply the new space-time transfinite interpolation to volumetric material attributes within this time gap. The proposed solution is analytical in its nature, does not require heavy numerical computations and can be used in real-time applications. Applications of this technique also include texturing and displacement mapping of time-variant surfaces, and parametric design of volumetric microstructures.
关键词： heterogeneous volume modelling,texturing,volumetric metamorphosis,material distribution,Scalar field,transfinite interpolation
更新于2025-09-23 15:19:57
-
A new metaphor-less algorithms for the photovoltaic cell parameter estimation
摘要： The performance of the solar photovoltaic (PV) system can be improved by an accurate modelling of the solar cells, but cell modelling is inaccurate due to the lack of precise solar cell parameters. To model a reliable solar PV cell, the required parameters will not be provided in the manufacturer’s datasheet. Therefore, it’s necessary to estimate the required parameters adequately. Thereby, with this observation, in this paper, proposed a simple multi-objective optimization algorithm to estimate the cell parameters. Various optimization algorithms address this issue; however, most of the algorithms produce suboptimal results due to local minima and premature convergence. So, this paper proposes two simple metaphor-less algorithms named as Rao-2 (R-II), and Rao-3 (R-III) algorithm to estimate the PV cell parameters. The performance of the proposed algorithms is compared with other well-known optimization algorithms to show the pro?ciency of the proposed algorithms. To validate the performance of the proposed algorithms, the estimated parameters are compared with experimental results, including statistical analysis. Moreover, from the results, it can be judged that the proposed algorithms are more suitable for the estimation of three types of solar PV models e?ectively.
关键词： Parameter estimation,PV modelling,Metaphor-less algorithm,Photovoltaic cell
更新于2025-09-23 15:19:57
-
A study on the heat distribution and oxidative modification of aged dammar films upon Er:YAG laser irradiation
摘要： This work shows the impact of one Er:YAG laser pulse to both the surface and bulk of aged dammar varnishes. Tests were performed in fluences ranging from 0.56 to 2.4J/cm2 and pulse durations of 100 and 300μs. Temperature changes upon irradiation were examined by (a) live recordings with an infrared thermal camera, and (b) determining the optical properties of the varnish, which allowed for estimates of the linear absorption coefficient and the temperature rise associated with the laser irradiation. Transmission and Fourier Transform Infrared (FTIR) spectroscopy studies captured increased energy transmissions through varnish films, as well as registering a reduction of hydroxides and carbon–hydrogen bonding as a function of fluence, respectively. FTIR and Differential Scanning Calorimetry (DSC) experimentally determined the absorption coefficient and the specific heat capacity of dammar films, and an overview of laser spots was carried out with Scanning Electron Microscopy (SEM). Evidence on the varnish response to Er:YAG laser irradiation is provided.
关键词： Er:YAG lasers,transmission,thermal effects,dammar varnish,analysis,modelling
更新于2025-09-23 15:19:57
-
Deformation Analysis Using B-Spline Surface with Correlated Terrestrial Laser Scanner Observationsa??A Bridge Under Load
摘要： The choice of an appropriate metric is mandatory to perform deformation analysis between two point clouds (PC)—the distance has to be trustworthy and, simultaneously, robust against measurement noise, which may be correlated and heteroscedastic. The Hausdor? distance (HD) or its averaged derivation (AHD) are widely used to compute local distances between two PC and are implemented in nearly all commercial software. Unfortunately, they are a?ected by measurement In this contribution, we focus on terrestrial laser scanner (TLS) observations and assess the impact of neglecting correlations on the distance computation when a mathematical approximation is performed. The results of the simulations are extended to real observations from a bridge under load. Highly accurate laser tracker (LT) measurements were available for this experiment: they allow the comparison of the HD and AHD between two raw PC or between their mathematical approximations regarding reference values. Based on these results, we determine which distance is better suited in the case of heteroscedastic and correlated TLS observations for local deformation analysis. Finally, we set up a novel bootstrap testing procedure for this distance when the PC are approximated with B-spline surfaces.
关键词： B-splines,Matérn covariance function,Hausdor? distance,surface modelling,terrestrial laser scanning,bootstrapping,deformation,averaged Hausdor? distance,correlations
更新于2025-09-23 15:19:57
-
Deep learning enabled inverse design in nanophotonics
摘要： Deep learning has become the dominant approach in artificial intelligence to solve complex data-driven problems. Originally applied almost exclusively in computer-science areas such as image analysis and nature language processing, deep learning has rapidly entered a wide variety of scientific fields including physics, chemistry and material science. Very recently, deep neural networks have been introduced in the field of nanophotonics as a powerful way of obtaining the nonlinear mapping between the topology and composition of arbitrary nanophotonic structures and their associated functional properties. In this paper, we have discussed the recent progress in the application of deep learning to the inverse design of nanophotonic devices, mainly focusing on the three existing learning paradigms of supervised-, unsupervised-, and reinforcement learning. Deep learning forward modelling i.e. how artificial intelligence learns how to solve Maxwell’s equations, is also discussed, along with an outlook of this rapidly evolving research area.
关键词： forward modelling,inverse design,nanophotonics,artificial intelligence,metamaterials,machine learning
更新于2025-09-23 15:19:57