- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Vertical fine structure and time evolution of plasma irregularities in the Es layer observed by a high-resolution Ca+ lidar
摘要： The vertical fine structures and the time evolution of plasma irregularities in the sporadic E (Es) layer were observed via calcium ion (Ca+) density measurements using a resonance scattering lidar with a high time-height resolution (5 s and 15 m) at Tachikawa (35.7°N, 139.4°E) on December 24, 2014. The observation successfully provided clearer fine structures of plasma irregularities, such as quasi-sinusoidal height variation, localized clumps, “cats-eye” structures, and twist structures, in the sporadic Ca+ (Ca+s) layers at around 100 km altitude. These fine structures suggested that the Kelvin–Helmholtz instabilities occurred in the neutral atmosphere whose density changed temporarily or spatially. The maximum Ca+ density in the Ca+s layer was two orders of magnitude smaller than the maximum electron density estimated from the critical frequency (foEs) simultaneously observed by the ionosonde at Kokubunji (35.7°N, 139.5°E). A strong positive correlation with a coefficient of 0.91 suggests that Ca+ contributes forming the Es layer as well as major metallic ions Fe+ and Mg+ in the lower thermosphere. Moreover, the formation of a new Ca+s layer at 110 km and the upward motions of the Ca+s layers at 100 km and 110 km were observed just after the sunrise time at the conjugation point. Although the presence or absence of a causal relationship with the sunrise time was not clear, a possible explanation for the formation and the upward motions of the Ca+s layers was the occurrence of strong horizontal wind, rather than the enhancement of the eastward electric field.
关键词： Calcium ion (Ca+) density,Ion upward flow,Mid-latitude,Resonance scattering lidar,Kelvin–Helmholtz instability,Sporadic E (Es) layer,Vertical fine structure,Lower thermosphere
更新于2025-09-23 15:22:29
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[IEEE 2017 IEEE International WIE Conference on Electrical and Computer Engineering (WIECON-ECE) - Dehradun (2017.12.18-2017.12.19)] 2017 IEEE International WIE Conference on Electrical and Computer Engineering (WIECON-ECE) - Calculating Optimum Angle for Solar Panels of Dhaka, Bangladesh for Capturing Maximum Irradiation
摘要： This paper calculates the most optimum angle for solar panel for 365 days of the year individually using geographical location of Dhaka, Bangladesh. Then it calculates total solar irradiation if any angle is kept constant for 365 days. Then it compares the outputs and determines angle for capturing maximum irradiation. Then it verifies the result with another method. The result presents optimum tilt angle for the city of Dhaka.
关键词： declination angle,bright sunshine hour,total solar irradiance,Latitude,optimum tilt angle,sunset angle,hour angle
更新于2025-09-23 15:21:21
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Multichannel Spatially Nonhomogeneous Focused Vector Vortex Beams for Quantum Experiments
摘要： The utilization of vector vortex beams (VVBs) in quantum experiments has recently become a topic of tremendous interest. However, achieving a focused, high-resolution, transmission-type, multichannel, and nonhomogeneously polarized VVB array remains a great challenge. Here, by introducing a degree of freedom on a high-order Poincaré sphere in the form of latitude-polarization control and locally tailoring the phase and transverse polarization distributions at the subwavelength scale, a single transmission-type dielectric metalens design for producing a multichannel, spatially nonhomogeneous, focused VVB array is demonstrated. Three special kinds of lattices (triangle, square, and rhombus) are demonstrated, yielding independently controllable orbital angular momentum states and polarization states of a tightly focused field in each channel. Furthermore, by using only the proposed metalens and a polarizer, a mode-demultiplexing system is realized with a mode crosstalk as low as ?34.8 dB for all four channels. The results offer a robust technological foundation for exploiting spatial degrees of freedom of structured light in the miniaturization and integration of quantum photonics devices.
关键词： mode crosstalk,metalens,mode-demultiplexing system,vector vortex beams,latitude polarization
更新于2025-09-19 17:15:36
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - The Case for Custom TMYa??s: Examples Using the NSRDB
摘要： A typical meteorological year (TMY) data set essentially represents an hourly compilation of median months constructed using multi-year datasets. Although TMY data sets are generated from irradiance data in the horizontal plane, they are used in photovoltaic (PV) modeling for systems inclined to various angles. This paper demonstrates that a POA TMY (plane of array TMY) generated by selecting median months from a timeseries dataset produces multi-year POA significantly different results than a POA TMY generated by transposing a TMY dataset constructed from horizontal data. In some months the differences can be more than 3%. These results point to the need for generating TMY’s using POA irradiance timeseries representing the orientation at which PV panels will be deployed.
关键词： NSRDB,POA,latitude tilt,typical POA year,single-axis tracking,typical meteorological year,TGPY,typical GHI-based POA year,TPY,plane of array
更新于2025-09-16 10:30:52
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Comprehensive modeling of the lithographic errors in laser direct write
摘要： Patterns written by laser direct write have a critical dimension (CD) bias dependence on the dose similar to other direct write methods, such as electron beam lithography, which can be explained by the exposure intensity distribution (EID) of the laser beam. In this study, a comprehensive model based on the EID is proposed to understand the pattern CD bias dependence on the dose, which is known as the exposure latitude. This model was supported by the results of the exposure tests on MicroChem S1800 resist on an Si wafer using the Heidelberg DWL66+ laser writer. The exposure latitudes of the patterns at both micrometer and submicrometer scale were measured. At the micrometer scale, the exposure latitudes were found to have no measurable dependence on the pattern size and the local pattern density. This conclusion does not hold at the submicrometer scale where the length scale is comparable to the width of the laser beam. This study proposes a way to convert the experimental exposure latitude data into the EID functions and fit these functions by assuming a Gaussian laser beam intensity distribution. All empirical observations are found to agree with the predictions made by the EID model. The authors also show that this model can help achieve dimensional accuracy, especially when there is a change in the exposure process. Moreover, it can be used to analyze and minimize the CD inconsistency between different runs found in the experiments. To reduce such inconsistency, overexposing combined with a negative bias applied to the pattern is suggested.
关键词： lithographic errors,exposure latitude,exposure intensity distribution,laser direct write,critical dimension bias
更新于2025-09-11 14:15:04