Qihou Zhou
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View article: Accurate Spectral Fitting in the Upper F‐Region Using the Randomly Coded Data of the Arecibo 430 MHz Radar
Accurate Spectral Fitting in the Upper F‐Region Using the Randomly Coded Data of the Arecibo 430 MHz Radar Open
Accurately resolving the ion composition in the upper F2 region and topside ionosphere remains a challenge due to temperature‐composition ambiguity and measurement limitations. This study presents a hybrid fitting algorithm that combines e…
View article: Statistical Analysis of Ionospheric Midnight Collapse Events Observed by Arecibo Incoherent Scatter Radar
Statistical Analysis of Ionospheric Midnight Collapse Events Observed by Arecibo Incoherent Scatter Radar Open
This study presents a comprehensive statistical analysis of ionospheric midnight collapse events over Arecibo, based on incoherent scatter radar (ISR) observations collected between 1971 and 2019. A total of 224 nights with valid measureme…
View article: First Observation of a Strong Thermospheric 4.8‐Hour Tide and Its Impact on the Ionosphere Over Arecibo
First Observation of a Strong Thermospheric 4.8‐Hour Tide and Its Impact on the Ionosphere Over Arecibo Open
We present an investigation of a prominent 4.8‐hr tidal wave observed at altitudes between 260 and 500 km, using data collected by the Arecibo incoherent scatter radar during March 17–20, 2015. Within this altitude range, the 4.8‐hr tide e…
View article: Make Still Further Progress: Chain of Thoughts for Tabular Data Leaderboard
Make Still Further Progress: Chain of Thoughts for Tabular Data Leaderboard Open
Tabular data, a fundamental data format in machine learning, is predominantly utilized in competitions and real-world applications. The performance of tabular models--such as gradient boosted decision trees and neural networks--can vary si…
View article: Representation Learning for Tabular Data: A Comprehensive Survey
Representation Learning for Tabular Data: A Comprehensive Survey Open
Tabular data, structured as rows and columns, is among the most prevalent data types in machine learning classification and regression applications. Models for learning from tabular data have continuously evolved, with Deep Neural Networks…
View article: Frequency-Domain Characterization of Finite Sample Linear Systems with Uniform Window Inputs
Frequency-Domain Characterization of Finite Sample Linear Systems with Uniform Window Inputs Open
We discuss determining a finite sample linear time-invariant (FS-LTI) system’s impulse response function, h[n], in the frequency domain when the input testing function is a uniform window function with a width of L and the output is limite…
View article: Iron-doped XC-72 enhancing cobalt selenide for high-efficiency oxygen evolution reaction
Iron-doped XC-72 enhancing cobalt selenide for high-efficiency oxygen evolution reaction Open
As an emerging class of anodic catalyst material for water electrolysis and hydrogen production, transition metal selenides exhibit excellent electron transport properties and multiphase structures with varying conductivities.
View article: Diurnal and Seasonal Variations of Sporadic Meteors Radiant Observed by Meteor Radars
Diurnal and Seasonal Variations of Sporadic Meteors Radiant Observed by Meteor Radars Open
Based on data collected from three meteor radars located at Mohe (MH, 53.5°N, 122.3°E), Wuhan (WH, 30.5°N, 114.6°E), and Ledong (LD, 18.4°N, 109.0°E), the diurnal and seasonal variations of the meteor counts, azimuth‐zenith distributions o…
View article: A Multivariable Study of a Traveling Ionosphere Disturbance Using the Arecibo Incoherent Scatter Radar
A Multivariable Study of a Traveling Ionosphere Disturbance Using the Arecibo Incoherent Scatter Radar Open
We present the first simultaneous observations of a traveling ionosphere wave (TID) event, measuring electron concentration (Ne), vertical plasma drift (Vz), and ion and electron temperatures (Ti, Te) using the Arecibo incoherent scatter r…
View article: Measurements of F<sub>1</sub>‐ Region Ionosphere State Variables at Arecibo Through Quasi Height‐Independent Exhaustive Fittings of the Incoherent Scatter Ion‐Line Spectra
Measurements of F<sub>1</sub>‐ Region Ionosphere State Variables at Arecibo Through Quasi Height‐Independent Exhaustive Fittings of the Incoherent Scatter Ion‐Line Spectra Open
We discuss an exhaustive search approach to fit the incoherent scatter spectrum (ISS) in the F 1 ‐region for molecular ion fraction ( f m ), ion temperature ( T i ), and electron temperature ( T e ). The commonly used “full profile” approa…
View article: Variance estimations in the presence of intermittent interference and their applications to incoherent scatter radar signal processing
Variance estimations in the presence of intermittent interference and their applications to incoherent scatter radar signal processing Open
We discuss robust estimations for the variance of normally distributed random variables in the presence of interference. The robust estimators are based on either ranking or the geometric mean. For the interference models used, estimators …
View article: On the Impulse Response of Singular Discrete LTI Systems and Three Fourier Transform Pairs
On the Impulse Response of Singular Discrete LTI Systems and Three Fourier Transform Pairs Open
A basic tenet of linear invariant systems is that they are sufficiently described by either the impulse response function or the frequency transfer function. This implies that we can always obtain one from the other. However, when the tran…
View article: Comment on egusphere-2024-256
Comment on egusphere-2024-256 Open
Abstract. We discuss robust estimations for the variance of normally distributed random variables in the presence of interferences. The robust estimators are based on either ranking or the geometric mean. For the interference models used, …
View article: Reply on RC1
Reply on RC1 Open
Abstract. We discuss robust estimations for the variance of normally distributed random variables in the presence of interferences. The robust estimators are based on either ranking or the geometric mean. For the interference models used, …
View article: Variance estimations in the presence of intermittent interferences and their applications to incoherent scatter radar signal processing
Variance estimations in the presence of intermittent interferences and their applications to incoherent scatter radar signal processing Open
We discuss robust estimations for the variance of normally distributed random variables in the presence of interferences. The robust estimators are based on either ranking or the geometric mean. For the interference models used, estimators…
View article: Seasonal Variations in Ion Density, Ion Temperature, and Migrating Tides in the Topside Ionosphere Revealed by ICON/IVM
Seasonal Variations in Ion Density, Ion Temperature, and Migrating Tides in the Topside Ionosphere Revealed by ICON/IVM Open
Based on the plasma parameters measured by the Ion Velocity Meter (IVM) instrument on the Ionospheric Connection Explorer (ICON) satellite from 2020 to 2021, we present an analysis of seasonal variations in ion density, ion temperature, an…
View article: Long-Term Observations of the Thermospheric 6 h Oscillation Revealed by an Incoherent Scatter Radar over Arecibo
Long-Term Observations of the Thermospheric 6 h Oscillation Revealed by an Incoherent Scatter Radar over Arecibo Open
We present an analysis of 6 h oscillations in the thermosphere ranging from 150 km to 400 km. The analysis applies 134 days of data from an incoherent scatter radar located at Arecibo Observatory (18.3°N, 66.7°W) from 1984 to 2015. To our …
View article: A Machine Learning Algorithm to Detect and Analyze Meteor Echoes Observed by the Jicamarca Radar
A Machine Learning Algorithm to Detect and Analyze Meteor Echoes Observed by the Jicamarca Radar Open
We present a machine-learning approach to detect and analyze meteor echoes (MADAME), which is a radar data processing workflow featuring advanced machine-learning techniques using both supervised and unsupervised learning. Our results demo…
View article: Incoherent scatter radar study of D-region gravity wave dynamics above Arecibo
Incoherent scatter radar study of D-region gravity wave dynamics above Arecibo Open
Arecibo incoherent scatter radar was the most powerful radar before its collapse in Dec. 1, 2020. Through its 57 years operation, it collected a large amount of ionospheric back scatter data. Although the radar is best known for studying t…
View article: Sporadic micro-meteoroid source radiant distribution inferred from the Arecibo 430 MHz radar observations
Sporadic micro-meteoroid source radiant distribution inferred from the Arecibo 430 MHz radar observations Open
This work presents the result of sporadic meteor radiant density distribution using the Arecibo 430 MHz incoherent scatter radar (ISR) located in Puerto Rico for the first time. Although numerous meteor studies have been carried out using …
View article: First Observational Evidence for the Role of Polar Vortex Strength in Modulating the Activity of Planetary Waves in the MLT Region
First Observational Evidence for the Role of Polar Vortex Strength in Modulating the Activity of Planetary Waves in the MLT Region Open
Based on the meteor winds measured at Mohe (MH; 53.5°N, 122.3°E) and the reanalysis data, we investigate the variations of planetary waves in the mesosphere and lower thermosphere (MLT) region during the 2019/2020 Arctic winter. Four strat…
View article: Comparison of stratospheric evolution during the major sudden stratospheric warming events in 2018 and 2019
Comparison of stratospheric evolution during the major sudden stratospheric warming events in 2018 and 2019 Open
Using Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) data in the northern hemisphere at the 10 hPa level, we compared the stratospheric evolution of temperature and geopotential height during two major…
View article: A Study on Meteor Head Echo Using a Probabilistic Detection Model at Jicamarca
A Study on Meteor Head Echo Using a Probabilistic Detection Model at Jicamarca Open
A coded long pulse is applied to the Jicamarca 50 MHz high power large aperture radar to study meteor head echoes. We develop a probabilistic detection model, which finds 25% more meteors than the commonly used signal‐to‐noise threshold me…
View article: Characteristics of the quasi-16-day wave in the mesosphere and lower thermosphere region as revealed by meteor radar, Aura satellite, and MERRA2 reanalysis data from 2008 to 2017
Characteristics of the quasi-16-day wave in the mesosphere and lower thermosphere region as revealed by meteor radar, Aura satellite, and MERRA2 reanalysis data from 2008 to 2017 Open
This study presents an analysis of the quasi-16-day wave (Q16DW) at three stations in the middle latitudes by using a meteor radar chain in conjunction with Aura Microwave Limb Sounder temperature data and MERRA2 (Modern-Era Retrospective …
View article: Effect of Temperature and Vertical Drift on Helium Ion Concentration Over Arecibo During Solar Maximum
Effect of Temperature and Vertical Drift on Helium Ion Concentration Over Arecibo During Solar Maximum Open
We present an analysis of helium ion (He + ) fraction in an altitude range from about 400 km to around 700 km and its relationship to the ion temperature ( T i ) and the vertical ion drift under solar maximum conditions. The data were obta…
View article: Velocity and orbital characteristics of micrometeors observed by the Arecibo 430 MHz incoherent scatter radar
Velocity and orbital characteristics of micrometeors observed by the Arecibo 430 MHz incoherent scatter radar Open
Using the Arecibo 430 MHz incoherent scatter radar located in Puerto Rico, we report the characteristics of the smallest meteors observed by any ground-based instruments. Coupled with an efficient pulse coding technique, the radar detects …
View article: Long-term lidar observations of the gravity wave activity near the mesopause at Arecibo
Long-term lidar observations of the gravity wave activity near the mesopause at Arecibo Open
Using 11-year-long K Doppler lidar observations of temperature profiles in the mesosphere and lower thermosphere (MLT) between 85 and 100 km, conducted at the Arecibo Observatory, Puerto Rico (18.35∘ N, 66.75∘ W), seasonal variations of me…
View article: A Study on the Quarterdiurnal Tide in the Thermosphere at Arecibo During the February 2016 Sudden Stratospheric Warming Event
A Study on the Quarterdiurnal Tide in the Thermosphere at Arecibo During the February 2016 Sudden Stratospheric Warming Event Open
Using data collected from the Arecibo incoherent scatter radar during 5–10 February 2016, we present a study on the quarterdiurnal tide (QDT) from 250 to 360 km. A sudden stratospheric warming (SSW) event occurred on 8 February coincided w…