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Decision making module based on stochastic magnetic tunnel junctions

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science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 202-209页

作者： Yifan Miao Li Zhao Yajun Zhang Zhe Yuan center for Advanced Quantum Studies and Department of Physics Beijing Normal University Institute for Nanoelectric Devices and Quantum Computing Fudan University interdisciplinary center for Theoretical Physics and Information sciences Fudan University

In biological neural systems, noise is ubiquitous but does not affect the correct decisions made in the complex cognitive ***-making in biological neural system is typically achieved by accumulating input information over a period of *** by recent developments in neurosciences, we design a decision-making module based on spintronic devices, utilizing superparamagnetic tunnel junctions as artificial neurons. The feasibility of this decision-making module is verified through circuit simulations. Taking a multi-layer perceptron as an example, the module significantly improves the accuracy of the perceptron in the handwritten digit recognition task. Furthermore, the spintronic decision-making module offers advantages over the conventional pooling methods, such as adaptive decision time, high performance and the absence of analog-to-digital conversion. The decision-making module is flexible to be integrated into artificial neural networks and provides a general yet effective solution to enhance performance against device noise.

关键词： neuromorphic computing spintronics magnetic tunnel junction neural networks

Constraints on what controls millennial-scale basin-wide denudation across mountain belts, Asia

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science China earth sciences 2025年第1期 74-93页

作者： Ye YANG Steven A.BINNIE Sheng XU Cong-Qiang LIU Tibor J.DUNAI Institute of Surface-earth system science School of Earth System Science Tianjin University Institute of Geology and Mineralogy University of Cologne

The terrestrial cosmogenic nuclide dataset consisting of 123310Be measurements of fluvial sediment samples across the Asian mountain belts is used to constrain the influence of climate,tectonics and topography on earth-surface denudation processes.10Be-derived basin-wide denudation rates were recalculated using a Monte Carlo simulation approach that relied on pixel-by-pixel production *** rates derived span four orders of magnitude,from 7.4±0.7 mm kyr-1（1σ;Central Tibetan Plateau） to 9,646744+777mm kyr-1（1σ;Southern Tibetan Plateau）,with a median of 186 mm *** our results with the traditional basin-wide production rate scaling model using a centroid coordinate and mean elevation,suggests that 96.6%of production rates will be underestimated using the latter method,especially for basins with a large *** bias between both methods reaches as large as 40%,caused by basin hypsometry and the nonlinear scaling of production rate with elevation and *** of the correlations between uniformly recalculated denudation rates and tectonics,climate,topography and rock lithology will facilitate the extrapolation of denudation rates in unknown basins using available *** the perspective of local scales,precipitation coupled with neotectonics-driven landslides is likely the most influential factor in subtropical Taiwan Island,while topography primarily constrains surface denudation rates in the eastern Tibetan Plateau within a narrow range of *** highland regions with glacier coverage,such as the Pamir,central and southern Tibetan Plateau high denudation rates are affected by glaciation,whereas lower precipitation and high erosion base level may limit river incision and evolving relief in the Central Tibetan *** contrast to local-scale findings highlighting a dominant factor constraining denudation rate,our large-scale quantitative analyses across the Asian mountain belts finds that （1） topographic metrics including

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Comparison of Advanced Technology Microwave Sounder Biases Estimated Using Radio Occultation and Hurricane Florence(2018) Captured by NOAA-20 and S-NPP

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Advances in Atmospheric sciences 2020年第3期37卷 269-277页

作者： Xiaoxu TIAN Xiaolei ZOU earth science system interdisciplinary center University of Maryland

The second Advanced Technology Microwave Sounder(ATMS)was onboard the National Oceanic and Atmospheric Administration(NOAA)-20 satellite when launched on 18 November *** nearly six months of the earliest NOAA-20 observations,the biases of the ATMS instrument were compared between NOAA-20 and the Suomi National Polar-Orbiting Partnership(S-NPP)*** biases of ATMS channels 8 to 13 were estimated from the differences between antenna temperature observations and model simulations generated from Meteorological Operational(MetOp)-A and MetOp-B satellites’Global Positioning system(GPS)radio occultation(RO)temperature and water vapor *** was found that the ATMS onboard the NOAA-20 satellite has generally larger cold biases in the brightness temperature measurements at channels 8 to 13 and small standard *** observations from ATMS on both S-NPP and NOAA-20 are shown to demonstrate an ability to capture a less than 1-h temporal evolution of Hurricane Florence(2018)due to the fact that the S-NPP orbits closely follow those of NOAA-20.

关键词： ATMS NOAA-20 S-NPP biases calibration Hurricane Florence

Striping Noise Analysis and Mitigation for Microwave Temperature Sounder-2 Observations

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Advances in Atmospheric sciences 2019年第7期36卷 711-720页

作者： Xiaolei ZOU Xiaoxu TIAN earth science system interdisciplinary center University of Maryland College Park

The Microwave Temperature Sounder(MWTS)-2 has a total of 13 temperature-sounding channels with the capability of observing radiance emissions from near the surface to the stratosphere. Similar to the Advanced Technology Microwave Sounder(ATMS), striping pattern noise, primarily in the cross-track direction, exists in MWTS-2 radiance observations. In this study, an algorithm based on principal component analysis(PCA) combined with ensemble empirical mode decomposition(EEMD) is described and applied to MWTS-2 brightness temperature observations. It is arguably necessary to smooth the first three principal component(PC) coefficients by removing the first four intrinsic mode functions(IMFs) using the EEMD method(denoted as PC3/IMF4). After the PC3/IMF4 noise mitigation, the striping pattern noise is effectively removed from the brightness temperature observations. The noise level in MWTS-2 observations is significantly higher than that detected in ATMS observations. In May 2014, the scanning profile of MWTS-2 was adjusted from varying-speed scanning to constantspeed scanning. The impact on striping noise levels brought on by this scan profile change is also analyzed here. The striping noise in brightness temperature observations worsened after the profile change. Regardless of the scan profile change, the striping noise mitigation method reported in this study can more or less suppress the noise levels in MWTS-2 observations.

关键词： MWTS-2 striping noise temperature sounding microwave radiometry

Glacial-Interglacial Atmospheric CO_2 Change——The Glacial Burial Hypothesis

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Advances in Atmospheric sciences 2003年第5期20卷 677-693页

作者： Ning ZENG Department of Meteorology and earth system science interdisciplinary center, University of Maryland, USA Department of Meteorology and earth system science interdisciplinary center University of Maryland USA

Organic carbon buried under the great ice sheets of the Northern Hemisphere is suggested to be the missing link in the atmospheric CO2 change over the glacial-interglacial cycles. At glaciation, the advancement of continental ice sheets buries vegetation and soil carbon accumulated during warmer periods. At deglaciation, this burial carbon is released back into the atmosphere. In a simulation over two glacial-interglacial cycles using a synchronously coupled atmosphere-land-ocean carbon model forced by reconstructed climate change, it is found that there is a 547-Gt terrestrial carbon release from glacial maximum to interglacial, resulting in a 60-Gt (about 30-ppmv) increase in the atmospheric CO2, with the remainder absorbed by the ocean in a scenario in which ocean acts as a passive buffer. This is in contrast to previous estimates of a land uptake at deglaciation. This carbon source originates from glacial burial, continental shelf, and other land areas in response to changes in ice cover, sea level, and climate. The input of light isotope enriched terrestrial carbon causes atmospheric δ13C to drop by about 0.3‰ at deglaciation, followed by a rapid rise towards a high interglacial value in response to oceanic warming and regrowth on land. Together with other ocean based mechanisms such as change in ocean temperature, the glacial burial hypothesis may offer a full explanation of the observed 80–100-ppmv atmospheric CO2 change.

关键词： atmospheric CO2 ice age glacial burial hypothesis climate

Development and Initial Assessment of a New Land Index for Microwave Humidity Sounder Cloud Detection

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Journal of Meteorological Research 2016年第1期30卷 12-37页

作者：秦正坤邹晓蕾 center of Data Assimilation for Research and Application Nanjing University of Information Science & Technology earth system science interdisciplinary center University of Maryland

This paper describes a new quality control （QC） scheme for microwave humidity sounder （MHS） data assimilation. It consists of a cloud detection step and an O-B （i.e., differences of brightness temperatures between observations and model simulations） check. Over ocean, cloud detection can be carried out based on two MHS window channels and two Advanced Microwave Sounding Unit-A （AMSU-A） window channels, which can be used for obtaining cloud ice water path （IWP） and liquid water path （LWP）, respectively. Over land, cloud detection of microwave data becomes much more challenging due to a much larger emission contribution from land surface than that from cloud. The current MHS cloud detection over land employs an 0-]3 based method, which could fail to identify cloudy radiances when there is mismatch between actual clouds and model clouds. In this study, a new MHS observation based index is developed for identifying MHS cloudy radiances over land. The new land index for cloud detection exploits the large variability of brightness temperature observations among MHS channels over different clouds, It is shown that those MHS cloudy radiances that were otherwise missed by the current O-B based QC method can be successfully identified by the new land index. An O-B check can then be employed to the remaining data after cloud detection to remove additional outliers with model simulations deviated greatly from observations. It is shown that MHS channel correlations are significantly reduced by the newly proposed QC scheme.

关键词： microwave humidity sounder cloud detection data assimilation

A transformative approach to enhance the parameter information from microwave and infrared remote sensing measurements

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Big earth Data 2020年第3期4卷 322-347页

作者： Prabhat K.Koner earth system science interdisciplinary center University of MarylandCollege ParkMDUSA

In observational science,data is the foundation of a scientific model;satellite-derived parameters serve as data for earth sciences *** building of science is imprecise if data is *** sensing‘big data’provides a wealth of information for unlocking the mysteries of earth *** parameter estimation from remote sensing measurements is extremely ill-posed and the inverse method plays a significant role in extracting parameter *** this paper,predominant stochastic inverse methods in satellite retrieval applications are critically investigated from different schools of thought and several basic flaws are revealed,*** being treated as definite *** major drawbacks of these methods include a high reliance on a priori information and binding the satellite retrievals to in situ measurements.A fundamentally different and transformative approach is explored as an alternative.A rational,reliable,and repeatable determination of geophysical parameter values from remote sensing measurements is possible using the total least squares based deterministic inverse *** is a physical model-based data-driven optimization,where the error quantity is extracted from the problem itself for regularization on a case-by-case basis using singular vector decomposition of the augmented function of the Jacobian and the *** moving from the prevalent to the proposed inverse method,a paradigm shift in results from“information loss”to‘information gain’is achieved.

关键词： Infrared microwave remote sensing radiative transfer inverse problem parameter information

First Surface-based Estimation of the Aerosol Indirect Effect over a Site in Southeastern China

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Advances in Atmospheric sciences 2018年第2期35卷 169-181页

作者： Jianjun LIU Zhanqing LI earth system science interdisciplinary center University of MarylandCollege Park State Laboratory of earth Surface Process and Resource Ecology College of Global Change and Earth System ScienceBeijing Normal University

The deployment of the U.S. Atmospheric Radiation Measurement mobile facility in Shouxian from May to December 2008 amassed the most comprehensive set of measurements of atmospheric, surface, aerosol, and cloud variables in China. This deployment provided a unique opportunity to investigate the aerosol-cloud interactions, which are most challenging and, to date, have not been examined to any great degree in China. The relationship between cloud droplet effective radius （CER） and aerosol index （AI） is very weak in summer because the cloud droplet growth is least affected by the competition for water vapor. Mean cloud liquid water path （LWP） and cloud optical depth （COD） significantly increase with increasing AI in fall. The sensitivities of CER and LWP to aerosol loading increases are not significantly different under different air mass conditions. There is a significant correlation between the changes in hourly mean AI and the changes in hourly mean CER, LWP, and COD. The aerosol first indirect effect （FIE） is estimated in terms of relative changes in both CER （FIEcER） and COD （FIEcoD） with changes in AI for different seasons and air masses. FIEcoD and FIEcER are similar in magnitude and close to the typical FIE value of - 0.23, and do not change much between summer and fall or between the two different air mass conditions. Similar analyses were done using spaceborne Moderate Resolution Imaging Spectroradiometer data. The satellite-derived FIE is contrary to the FIE estimated from surface retrievals and may have large uncertainties due to some inherent limitations.

关键词： ground-based measurements aerosol indirect effect southeastern China

Model Evidence for Interdecadal Pathway Changes in the Subtropics and Tropics of the South Pacific Ocean

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Advances in Atmospheric sciences 2013年第1期30卷 1-9页

作者：张荣华王彰贵 earth system science interdisciplinary center University of MarylandCollege ParkMarylandUSA College of Global Change and earth system science Beijing Normal University National Marine Environmental Forecasting center State Oceanic Administration

Numerical simulations using a version of the GFDL/NOAA Modular Ocean Model （MOM 3） are analyzed to demonstrate interdecadal pathway changes from the subtropics to the tropics in the South Pacific Ocean. After the 1976 -77 climate shift, the subtropical gyre of the South Pacific underwent significant changes, characterized by a slowing down in its circulation and a southward displacement of its center by about 5°- 10° latitude on the western side. The associated circulation altered its flow path in the northwestern part of the subtropical gyre, changing from a direct pathway connecting the subtropics to the tropics before the shift to a more zonal one after. This effectively prevented some subtropical waters from directly entering into the western equatorial Pacific. Since waters transported onto the equator around the subtropical gyre are saline and warm, such changes in the direct pathway and the associated reduction in equatorward exchange from the subtropics to the tropics affected water mass properties downstream in the western equatorial Pacific, causing persisted freshening and cooling of subsurface water as observed after the late 1970s. Previously, changes in gyre strength and advection of temperature anomalies have been invoked as mechanisms for linking the subtropics and tropics on interdecadal time scales. Here we present an additional hypothesis in which geographic shifts in the gyre structure and location （a pathway change） could play a similar role.

关键词： water pathway interdecadal changes ocean modeling South Pacific Ocean