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K-Means Clustering with Local Distance Privacy

Big Data Mining and Analytics 2023年第4期6卷 433-442页

作者： Mengmeng Yang Longxia Huang Chenghua Tang the Data61 Commonwealth Scientific and Industrial Research OrganizationMelbourne 3168Australia the School of Computer Science and Communication Engineering Jiangsu UniversityZhenjiang 212013China. the School of Computer Science and Information Security Guilin University of Electronic TechnologyGuilin 541010China

With the development of information technology,a mass of data are generated every day.Collecting and analysing these data help service providers improve their services and gain an advantage in the fierce market competition.K-means clustering has been widely used for cluster analysis in real life.However,these analyses are based on users’data,which disclose users’privacy.Local differential privacy has attracted lots of attention recently due to its strong privacy guarantee and has been applied for clustering analysis.However,existing K-means clustering methods with local differential privacy protection cannot get an ideal clustering result due to the large amount of noise introduced to the whole dataset to ensure the privacy guarantee.To solve this problem,we propose a novel method that provides local distance privacy for users who participate in the clustering analysis.Instead of making the users’records in-distinguish from each other in high-dimensional space,we map the user’s record into a one-dimensional distance space and make the records in such a distance space not be distinguished from each other.To be specific,we generate a noisy distance first and then synthesize the high-dimensional data record.We propose a Bounded Laplace Method(BLM)and a Cluster Indistinguishable Method(CIM)to sample such a noisy distance,which satisfies the local differential privacy guarantee and local dE-privacy guarantee,respectively.Furthermore,we introduce a way to generate synthetic data records in high-dimensional space.Our experimental evaluation results show that our methods outperform the traditional methods significantly.

关键词： K-means clustering local differential privacy data analysis

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PTMOT: A Probabilistic Multiple Object Tracker Enhanced by Tracklet Confidence for Autonomous Driving

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Automotive Innovation 2022年第3期5卷 260-271页

作者： Kun Jiang Yining Shi Taohua Zhou Mengmeng Yang Diange yang State Key Lab of Automotive Safety and Energy Center for Intelligent Connected Vehicles and TransportationSchool of Vehicle and MobilityTsinghua UniversityLee Shau Kee Building No A639Beijing 100084China

Real driving scenarios,due to occlusions and disturbances,provide disordered and noisy measurements,which makes the task of multi-object tracking quite challenging.Conventional approach is to find deterministic data association;however,it has unstable performance in high clutter density.This paper proposes a novel probabilistic tracklet-enhanced multiple object tracker(PTMOT),which integrates Poisson multi-Bernoulli mixture(PMBM)filter with confidence of tracklets.The proposed method is able to realize efficient and robust probabilistic association for 3D multi-object tracking(MOT)and improve the PMBM filter’s continuity by smoothing single target hypothesis with global hypothesis.It consists of two key parts.First,the PMBM tracker based on sets of tracklets is implemented to realize probabilistic fusion of disordered measure-ments.Second,the confidence of tracklets is smoothed through a smoothing-while-filtering approach.Extensive MOT tests on nuScenes tracking dataset demonstrate that the proposed method achieves superior performance in different modalities.

关键词： 3D multi-object tracking Random finite set Probabilistic association Tracklet confidence smoothing

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Severe disseminated intravascular coagulation complicated by acute renal failure during pregnancy

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World Journal of Emergency Medicine 2023年第5期14卷 411-413页

作者： Yuqun Pu Jingping Zhu Baihui Zhao Mengmeng Yang Qiong Luo Department of Obstetrics Women’s HospitalSchool of MedicineZhejiang UniversityHangzhou 310006China

Disseminated intravascular coagulation (DIC)is a clinical syndrome caused by various etiologies and characterized by systemic activation of blood coagulation,leading to vessel thrombosis,organ dysfunction,and severe bleeding.^([1])DIC represents a life-threatening condition that is the endpoint of uncontrolled systemic activation of the disease.Once it enters the stage of malignant DIC,the patient’s death becomes unavoidable.DIC always occurs as a secondary disorder and is commonly associated with postpartum hemorrhage,followed by hypertensive disorders,acute fatty liver of pregnancy,sepsis,and amniotic fluid embolism (AFE).^([2])In clinical obstetrics,DIC often occurs during delivery or postpartum.

关键词： pregnancy death DIC

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Crowdsourced Road Semantics Mapping Based on Pixel-Wise Confidence Level

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Automotive Innovation 2022年第1期5卷 43-56页

作者： Benny Wijaya Kun Jiang Mengmeng Yang Tuopu Wen Xuewei Tang Diange yang State Key Laboratory of Automotive Safety and Energy and Center for Intelligent Connected Vehicles and TransportationTsinghua UniversityBeijing 100084China

High-definition map has become a vital cornerstone in the navigation of autonomous vehicles in complex traffic scenarios.Thus,the construction of high-definition maps has become crucial.Traditional methods relying on expensive mapping vehicles equipped with high-end sensor equipment are not suitable for mass map construction because of the limitation imposed by its high cost.Hence,this paper proposes a new method to create a high-definition road semantics map using multi-vehicle sensor data.The proposed method implements crowdsourced point-based visual SLAM to align and combine the local maps derived by multiple vehicles.This allows users to modify the extraction process by using a more sophisticated neural network,thus achieving a more accurate detection result when compared with traditional binarization method.The resulting map consists of road marking points suitable for autonomous vehicle navigation and path-planning tasks.Finally,the method is evaluated on the real-world KAIST urban dataset and Shougang dataset to demonstrate the level of detail and accuracy of the proposed map with 0.369 m in mapping errors in ideal condition.

关键词： Crowdsourced mapping Map fusion SLAM Semantic mapping

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GCD‑L: A Novel Method for Geometric Change Detection in HD Maps Using Low‑Cost Sensors

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Automotive Innovation 2022年第3期5卷 324-332页

作者： Peng Sun Yunpeng Wang Peng He Xinxin Pei Mengmeng Yang Kun Jiang Diange yang Autonomous Driving Technology Baidu IncBeijingChina School of Vehicle and Mobility Tsinghua UniversityLee Shau Kee Building No A639Beijing 100084China

Updating high-definition maps is imperative for the safety of autonomous vehicles.However,positional changes in lane lines are hard to be detected in a timely manner due to a limited number of expensive surveying vehicles over a large geo-graphic area.Herein,a novel method is proposed to detect the geometric changes of lane lines using low-cost sensors,such as consumer-grade global navigation satellite system(GNSS)hardware receivers and cameras.The proposed framework geometric change detection using low-cost sensors(GCD-L)and algorithm change segment compare(CSC),which are based on the lane width between the curb line and the adjacent leftmost lane line,can perceive the positional changes of the leftmost lane line on highway and expressway roads.The effectiveness of the proposed method is verified by evaluating it on a real-world typical urban ring road dataset.The experimental results show that 71%detected change segments are valid with only two round crowdsourced maps.

关键词： Autonomous driving HD Maps Lane line Change detection

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The response of structure and nitrogen removal function of the biofilm on submerged macrophytes to high ammonium in constructed wetlands

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Journal of Environmental Sciences 2024年第8期142卷 129-141页

作者： Xue Jiang mengmeng Wang Shunqing yang Di He Fei Fang Liuyan yang State Key Laboratory of Pollution Control and Resource Reuse School of the EnvironmentNanjing UniversityNanjing 210023China School of Resources and Environment Anqing Normal UniversityAnqing 246133China

The ammonium exceedance discharge from sewage treatment plants has a great risk to the stable operation of subsequent constructed wetlands(CWs).The effects of high ammonium shocks on submerged macrophytes and epiphytic biofilms on the leaves of submerged macrophytes in CWs were rarely mentioned in previous studies.In this paper,the 16S rRNA sequencing method was used to investigate the variation of the microbial communities in biofilms on the leaves of Vallisneria natans plants while the growth characteristics of V.natans plants were measured at different initial ammonium concentrations.The results demonstrated that the total chlorophyll and soluble sugar synthesis of V.natans plants decreased by 51.45%and 57.16%,respectively,and malondialdehyde content increased threefold after8 days if the initial NH_(4)^(+)-N concentration was more than 5 mg/L.Algal density,bacterial quantity,dissolved oxygen,and pH increased with high ammonium shocks.The average removal efficiencies of total nitrogen and NH_(4)^(+)-N reached 73.26%and 83.94%,respectively.The heat map and relative abundance analysis represented that the relative abundances of phyla Proteobacteria,Cyanobacteria,and Bacteroidetes increased.The numbers of autotrophic nitrifiers and heterotrophic nitrification aerobic denitrification(HNAD)bacteria expanded in biofilms.In particular,HNAD bacteria of Flavobacterium,Hydrogenophaga,Acidovorax,Acinetobacter,Pseudomonas,Aeromonas,and Azospira had higher abundances than autotrophic nitrifiers because there were organic matters secreted from declining leaves of V.natans plants.The analysis of the nitrogen metabolic pathway showed aerobic denitrification was the main nitrogen removal pathway.Thus,the nitrification and denitrification bacterial communities increased in epiphytic biofilms on submerged macrophytes in constructed wetlands while submerged macrophytes declined under ammonium shock loading.

关键词： Ammonium shock loading Biofilm Autotrophic nitrifiers Heterotrophic nitrification aerobic denitrification bacteria Submerged macrophyte

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Photocatalytic nitrogen reduction to ammonia:Insights into the role of defect engineering in photocatalysts

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Nano Research 2022年第4期15卷 2773-2809页

作者： Huidong Shen Mengmeng Yang Leiduan Hao Jinrui Wang Jennifer Strunk Zhenyu Sun State Key Laboratory of Organic-Inorganic Composites College of Chemical EngineeringBeijing University of Chemical TechnologyBeijing 100029China Leibniz Institute for Catalysis at the University of Rostock Rostock 18059Germany

Engineering of defects in semiconductors provides an effective protocol for improving photocatalytic N_(2) conversion efficiency.This review focuses on the state-of-the-art progress in defect engineering of photocatalysts for the N_(2) reduction toward ammonia.The basic principles and mechanisms of thermal catalyzed and photon-induced N_(2) reduction are first concisely recapped,including relevant properties of the N_(2) molecule,reaction pathways,and NH3 quantification methods.Subsequently,defect classification,synthesis strategies,and identification techniques are compendiously summarized.Advances of in situ characterization techniques for monitoring defect state during the N_(2) reduction process are also described.Especially,various surface defect strategies and their critical roles in improving the N_(2) photoreduction performance are highlighted,including surface vacancies(i.e.,anionic vacancies and cationic vacancies),heteroatom doping(i.e.,metal element doping and nonmetal element doping),and atomically defined surface sites.Finally,future opportunities and challenges as well as perspectives on further development of defect-engineered photocatalysts for the nitrogen reduction to ammonia are presented.It is expected that this review can provide a profound guidance for more specialized design of defect-engineered catalysts with high activity and stability for nitrogen photochemical fixation.

关键词： photocatalysis nitrogen reduction ammonia synthesis defect engineering

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Hierarchical porous nitrogen,oxygen,and phosphorus ternary doped hollow biomass carbon spheres for high-speed and long-life potassium storage

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Carbon Energy 2022年第1期4卷 45-59页

作者： Mengmeng Yang Qingquan Kong Wei Feng Weitang Yao Qingyuan Wang School of Mechanical Engineering Chengdu UniversityChengduSichuanChina Institute of Chemical Materials China Academy of Engineering PhysicsMianyangSichuanChina

Limited lithium resources have promoted the exploration of new battery technologies.Among them,potassium-ion batteries are considered as promising alternatives.At present,commercial graphite and other carbon-based materials have shown good prospects as anodes for potassium-ion batteries.However,the volume expansion and structural collapse caused by periodic K+insertion/extraction have severely restricted further development and application of potassium-ion batteries.A hollow biomass carbon ball(NOP-PB)ternarily doped with N,O,and P was synthesized and used as the negative electrode of a potassium-ion battery.X-ray photoelectron spectroscopy,Fourier‐transform infrared spectroscopy,and transmission electron microscopy confirmed that the hollow biomass carbon spheres were successfully doped with N,O,and P.Further analysis proved that N,O,and P ternary doping expands the interlayer distance of the graphite surface and introduces more defect sites.DFT calculations simultaneously proved that the K adsorption energy of the doped structure is greatly improved.The solid hollow hierarchical porous structure buffers the volume expansion of the potassium insertion process,maintains the original structure after a long cycle and promotes the transfer of potassium ions and electrons.Therefore,the NOP‐PB negative electrode shows extremely enhanced electrochemical performance,including high specific capacity,excellent long‐term stability,and good rate stability.

关键词： anodes hierarchical porous hollow carbon spheres N/O/P co-doping potassium-ion batteries

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Ligand engineering of perovskite quantum dots for efficient and stable solar cells

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Journal of Energy Chemistry 2022年第6期31卷 626-648,I0018页

作者： Shanshan Ding mengmeng Hao Tongen Lin yang Bai Lianzhou Wang School of Chemical Engineering and Australian Institute of Bioengineering and Nanotechnology The University of QueenslandBrisbaneQLD 4072Australia

Lead halide perovskite quantum dots(PQDs) have recently emerged as promising light absorbers for photovoltaic application due to their extraordinary optoelectronic properties. Surface ligands are of utmost importance for the colloidal stability and property tuning of PQDs, while their highly dynamic binding nature not only impedes further efficiency improvement of PQD-based solar cells but also induces intrinsic instability. Tremendous efforts have been made in ligand engineering with good hopes to solve such challenging issues in the past few years. In this review, we first present a fundamental understanding of the role of surface ligands in PQDs, followed by a brief discussion and classification of various ligands that have the potential for improving the electronic coupling and stability of PQD solids. We then provide a critical overview of recent advances in ligand engineering including the strategies of in-situ ligand engineering, postsynthesis/-deposition ligand-exchange, and interfacial engineering, and discuss their impacts on changing the efficiency and stability of perovskite QD solar cells(QDSCs). Finally, we give our perspectives on the future directions of ligand engineering towards more efficient and stable perovskite QDSCs.

关键词： Perovskite quantum dots Ligand engineering Defect passivation Solar cells Stability

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Coherent Chemical Variation Trends of the 55-25 Ma Magmatic Rocks in SE Tibet:N-S Direction Lithospheric Stretching of Eurasia during Early Stage of India-Eurasia Collision

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地质学报:英文版 2023年第5期97卷 1283-1305页

作者： yang Tiannan DONG mengmeng XUE Chuandong XIN Di LIANG Mingjuan Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China Chinese MNR Laboratory of Deep Earth Sciences and Technology Beijing 100037China Department of Earth Sciences Kunming University of Science and TechnologyKunming 650093China Geological Museum of Guizhou Guiyang 550081China

The progressive indentation of India into Eurasia generated an E-W-trending orthogonal collision belt and a N-S-trending oblique collision belt.Compiling available data reveals that~70%of the Cenozoic igneous rocks in eastern and southeastern Tibet are concentrated within an ENE-trending,~550-km long and~250-km wide magmatic zone(CMZ)that once separated the orthogonal and oblique collision belts.The Latitude 26°N Line is now its southern boundary.The onset timing of magmatism of the CMZ varies gradually from~55 Ma in the westernmost part to~27 Ma in the easternmost.Then the magmatism successively occurred and suddenly stopped at~25 Ma.The segmented and coherent chemical variation trends found suggest that the CMZ magmatic rocks were formed due to partial melting of the heterogeneous upper mantle and crusts of Eurasia.Subduction of Paleo-and Neotethyan oceanic plates generated this compositional and mineralogical heterogeneity.Combined with available geophysical data,the CMZ was diachronously formed in response to asthenosphere upwelling induced by NNW-SSE-direction lithosphere stretching.The difference in responses of the orthogonal and oblique collision belts to the indentation of the Indian continent has led to this lithosphere stretching.

关键词： tectonics geochemistry magmatic zone temporal/spatial distribution lithospheric stretch Eocene to Oligocene SE Tibet

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