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Surrogate-Based Uncertainty Analysis for Groundwater Contaminant Transport in a Chromium Residue Site Located in Southern china

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WATER 2024年第5期16卷 638页

作者： Zou, Yanhong Yousaf, Muhammad Shahzad Yang, Fuqiang Deng, Hao He, Yong Cent South Univ Key Lab Metallogen Predict Nonferrous Met & Geol E Minist Educ Changsha 410083 Peoples R China Cent South Univ Sch Geosci & Info Phys Changsha 410083 Peoples R China

Numerical modeling is widely acknowledged as a highly precise method for understanding the dynamics of contaminant transport in groundwater. However, due to the intricate characteristics of environmental systems and the lack of accurate information, the results are susceptible to a significant degree of uncertainty. Numerical models must explicitly consider related uncertainties in parameters to facilitate robust decision-making. In a Chromium Residue Site located in southern china (the study area), this study employed Monte Carlo simulation to assess the impact of variability in key parameters uncertainty on the simulation outcomes. Variogram analysis of response surface (VARS), global sensitivity analysis, and an XGBoost (version 2.0.0)-based surrogate model was employed to overcome the substantial computational cost of Monte Carlo simulation. The results of numerical simulation indicate that the contaminant is spreading downstream towards the northern boundary of contaminated site near Lianshui River, threatening water quality. Furthermore, migration patterns are complex due to both downstream convection and upstream diffusion. Sensitivity analysis identified hydraulic conductivity, recharge rate, and porosity as the most influential model parameters, selected as key parameters. Moreover, uncertainty analysis indicated that the variability in key parameters has a minimal impact on the simulation outcomes at monitoring wells near the contaminant source. In contrast, at wells positioned a considerable distance from the contaminant source, the variability in key parameters significantly influences the simulation outcomes. The surrogate model markedly mitigated computational workload and calculation time, while demonstrating superior precision and effectively capture the non-linear correlations between input and output of the simulation model.

关键词： numerical modeling Monte Carlo simulation VARS global sensitivity analysis surrogate model uncertainty analysis

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High-level production of chitinase by multi-strategy combination optimization in Bacillus licheniformis

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WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY 2024年第6期40卷 181-181页

作者： Qi, Zhimin Lei, Bo Xiong, Min Li, Weijia Liao, Yongqing Cai, Dongbo Ma, Xin Zhang, Ruibin Chen, Shouwen Hubei Univ Coll Life Sci Environm Microbial Technol Ctr Hubei Prov State Key Lab Biocatalysis & Enzyme Engn 368 Youyi Ave Wuhan 430062 Hubei Peoples R China

In view of the extensive potential applications of chitinase (ChiA) in various fields such as agriculture, environmental protection, medicine, and biotechnology, the development of a high-yielding strain capable of producing chitinase with enhanced activity holds significant importance. The objective of this study was to utilize the extracellular chitinase from Bacillus thuringiensis as the target, and Bacillus licheniformis as the expression host to achieve heterologous expression of ChiA with enhanced activity. Initially, through structural analysis and molecular dynamics simulation, we identified key amino acids to improve the enzymatic performance of chitinase, and the specific activity of chitinase mutant D116N/E118N was 48% higher than that of the natural enzyme, with concomitant enhancements in thermostability and pH stability. Subsequently, the expression elements of ChiA(D116N/E118N) were screened and modified in Bacillus licheniformis, resulting in extracellular ChiA activity reached 89.31 U/mL. Further efforts involved the successful knockout of extracellular protease genes aprE, bprA and epr, along with the gene clusters involved in the synthesis of by-products such as bacitracin and lichenin from Bacillus licheniformis. This led to the development of a recombinant strain, DW2 triangle abelA, which exhibited a remarkable improvement in chitinase activity, reaching 145.56 U/mL. To further improve chitinase activity, a chitinase expression frame was integrated into the genome of DW2 triangle abelA, resulting in a significant increas to 180.26 U/mL. Optimization of fermentation conditions and medium components further boosted shake flask enzyme activity shake flask enzyme activity, achieving 200.28 U/mL, while scale-up fermentation experiments yielded an impressive enzyme activity of 338.79 U/mL. Through host genetic modification, expression optimization and fermentation optimization, a high-yielding ChiA strain was successfully constructed, which will prov

关键词： Bacillus licheniformis Chitinase Fermentation optimization Protein engineering Host modification

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DeviceRadar: Online IoT Device Fingerprinting in ISPs Using programmable Switches

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IEEE-ACM TRANSACTIONS ON NETWORKING 2024年第5期32卷 3854-3869页

作者： Li, Ruoyu Li, Qing Lin, Tao Zou, Qingsong Zhao, Dan Huang, Yucheng Tyson, Gareth Xie, Guorui Jiang, Yong Tsinghua Univ Shenzhen Int Grad Sch Shenzhen 518055 Peoples R China Peng Cheng Lab Dept Strateg & Adv Interdisciplinary Res Shenzhen 518000 Peoples R China Tsinghua Univ Shenzhen Int Grad Sch Shenzhen 518055 Peoples R China Hong Kong Univ Sci & Technol Guangzhou Dept Elect & Comp Engn Guangzhou 511455 Peoples R China

Device fingerprinting can be used by Internet Service Providers (ISPs) to identify vulnerable IoT devices for early prevention of threats. However, due to the wide deployment of middleboxes in ISP networks, some important data, e.g., 5-tuples and flow statistics, are often obscured, rendering many existing approaches invalid. It is further challenged by the high-speed traffic of hundreds of terabytes per day in ISP networks. This paper proposes DeviceRadar, an online IoT device fingerprinting framework that achieves accurate, real-time processing in ISPs using programmable switches. We innovatively exploit "key packets" as a basis of fingerprints only using packet sizes and directions, which appear periodically while exhibiting differences across different IoT devices. To utilize them, we propose a packet size embedding model to discover the spatial relationships between packets. Meanwhile, we design an algorithm to extract the "key packets" of each device, and propose an approach that jointly considers the spatial relationships and the key packets to produce a neighboring key packet distribution, which can serve as a feature vector for machine learning models for inference. Last, we design a model transformation method and a feature extraction process to deploy the model on a programmable data plane within its constrained arithmetic operations and memory to achieve line-speed processing. Our experiments show that DeviceRadar can achieve state-of-the-art accuracy across 77 IoT devices with 40 Gbps throughput, and requires only 1.3% of the processing time compared to GPU-accelerated approaches.

关键词： IoT fingerprinting programmable data plane

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Voltage Regulation Enhanced Hierarchical Coordinated Volt/Var and Volt/Watt Control for Active Distribution Networks With Soft Open Points

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IEEE TRANSACTIONS ON SUSTAINABLE ENERGY 2024年第3期15卷 2021-2037页

作者： Hou, Qilin Dai, Ningyi Huang, Ying Univ Macau State Key Lab Internet Things Smart City Macau 999078 Peoples R China Univ Macau Dept Elect & Comp Engn Macau 999078 Peoples R China Zhejiang Univ Coll Elect Engn Hangzhou 310027 Peoples R China

The integration of renewable energy sources (RESs) into active distribution networks (ADNs) is essential for reducing carbon emissions but often results in voltage fluctuations and violations. This paper proposes a hierarchical voltage control framework that effectively coordinates diverse controllable devices with various response times in an ADN. The framework comprises three stages: day-ahead scheduling of on-load tap changer (OLTC), intra-day optimization for droop slopes and references for droop controllers in Soft Open Points (SOPs) and distributed generators (DGs), and real-time local voltage regulation. Unlike existing approaches, the proposed approach analytically establishes voltage stability constraints and incorporates them into droop slope optimization for local controllers, mitigating voltage oscillation risks. Additionally, a novel deviation-aware optimization method is developed to calculate optimal voltage references. This method treats the deviations between fixed-point voltages and their references as uncertainties and accounts for their impacts on voltage security through chance-constrained programming. Simulation results demonstrate the effectiveness of the proposed framework in improving voltage regulation performance with guaranteed stability.

关键词： Voltage control Real-time systems Stability analysis Inverters Optimization Uncertainty Time factors Soft open points hierarchical voltage control voltage regulation active distribution networks

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SPAIC: A Spike-Based Artificial Intelligence Computing Framework

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IEEE COMPUTATIONAL INTELLIGENCE MAGAZINE 2024年第1期19卷 51-65页

作者： Hong, Chaofei Yuan, Mengwen Zhang, Mengxiao Wang, Xiao Zhang, Chengjun Wang, Jiaxin Pan, Gang Tang, Huajin Zhejiang Lab Hangzhou Peoples R China Zhejiang Univ Hangzhou Peoples R China

Neuromorphic computing is an emerging research field that aims to develop new intelligent systems by integrating theories and technologies from multiple disciplines, such as neuroscience, deep learning and microelectronics. Various software frameworks have been developed for related fields, but an efficient framework dedicated to spike-based computing models and algorithms is lacking. In this work, we present a Python-based spiking neural network (SNN) simulation and training framework, named SPAIC, that aims to support brain-inspired model and algorithm research integrated with features from both deep learning and neuroscience. To integrate different methodologies from multiple disciplines and balance flexibility and efficiency, SPAIC is designed with a neuroscience-style frontend and a deep learning-based backend. Various types of examples are provided to demonstrate the wide usability of the framework, including neural circuit simulation, deep SNN learning and neuromorphic applications. As a user-friendly, flexible, and high-performance software tool, it will help accelerate the rapid growth and wide applicability of neuromorphic computing methodologies.

关键词： Deep learning Training Neuroscience Neuromorphic engineering Computational modeling Software algorithms Neural circuits

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A Real-Time Faint Space Debris Detector With Learning-Based LCM

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IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 2024年 73卷 1-1页

作者： Lu, Zherui Wang, Gangyi Wei, Xinguo Li, Jian Beihang Univ Sch Instrumentat & Optoelect Engn Beijing 100191 Peoples R China

With the development of aerospace technology, the increasing population of space debris has posed a great threat to the safety of spacecraft. Because of the small volume and long distance, space debris tends to have low signal-to-noise ratio (SNR), and while taking the limitations of ground observation methods into account, it is necessary to enhance the spacecraft's capacity for space situational awareness (SSA). Besides, the active search and long exposure time of the surveillance system will extend the star spot to be a streak-like target, making image enhancement and target extraction more difficult. Considering that traditional methods have some defects in low-SNR streak detection, such as low effectiveness and large time consumption, this article proposes a method for low-SNR streak extraction based on local contrast and maximum likelihood estimation (MLE), which can detect spatial objects with SNR 2.0 efficiently. In the proposed algorithm, local contrast will be applied for crude classifications, which will return connected components as preliminary results, then MLE will be performed to reconstruct the connected components of targets via orientated growth and the precision can be further improved. The algorithm has been verified with both simulated streaks and real star tracker images, and the average centroid error of the proposed algorithm is close to the state-of-the-art method like the optimal directional connected component (ODCC). At the same time, the algorithm in this article has significant advantages in efficiency compared with the ODCC. In conclusion, the algorithm in this article is of high speed and precision, which guarantees its promising applications in the extraction of high dynamic targets.

关键词： High dynamic streaks local contrast map maximum likelihood estimation (MLE) onboard camera space object extraction

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Ultrastable and Phosphoric Acid-Resistant PtRhCu@Pt Oxygen Reduction Electrocatalyst for High-Temperature Polymer Electrolyte Fuel Cells

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ACS CATALYSIS 2024年第4期14卷 2572-2581页

作者： An, Zhao Li, Huanqiao Zhang, Xiaoming Xia, Zhangxun Zhang, Hong Chu, Wenling Yu, Shansheng Wang, Suli Sun, Gongquan Chinese Acad Sci Dalian Inst Chem Phys Div Fuel Cells & Battery Dalian Natl Lab Clean Energy Dalian 116023 Peoples R China Chinese Acad Sci Key Lab Fuel Cell & Hybrid Power Sources Dalian 116023 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China Chinese Acad Sci Dalian Inst Chem Phys State Key Lab Catalysis Dalian 116023 Peoples R China Jilin Univ Dept Mat Sci Changchun 130012 Peoples R China

With much enhanced fuel flexibility to overcome the shortcomings of hydrogen production and storage, high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) are still facing challenges of activity loss of oxygen reduction electrocatalyst under the working circumstance of phosphoric acid (PA) electrolyte. Dissolution and leaching of metal component of PtM (M = Cu, Co, Ni) electrocatalysts is one of the key factors that degrade their initial resistance toward PA and hinder the accessing of activity and durability simultaneously. Here, we report an ultradurable PtRhCu@Pt/C electrocatalyst with a high mass activity of 0.90 A mg(Pt)(-1), which only decreased by 14.4% after 30K ADT cycles in the half-cell and reaches the DOE at 2025 target (<30 mV at 0.8 A cm(-2)) with 27 mV voltage loss at 0.8 A cm(-2) in the single-cell. After adding 0.1 M PA into the electrolyte, the half-wave potential of PtRhCu@Pt/C is negatively shifted by only 52 mV, much lower than that of commercial Pt/C (90 mV). Moreover, the HT-PEMFC assembled by this catalyst delivers a preeminent peak power density of 529 and 977 mW cm(-2) under H-2-air and H-2-O-2 conditions, respectively. Experiments and theoretical calculations reveal that the ligand effect arising from the sublayer Cu is attributed to the ability of PA resistance, while the self-healing behavior and the synergy between the PtRhCu core and the Pt shell ensures high stability.

关键词： HT-PEMFCs oxygen reduction reaction phosphoricacid resistance electrocatalysts core-shell self-healing stability

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Piperazine-derived ionizable lipids for enhanced mRNA delivery and cancer immunotherapy

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Nano research 2024年第8期17卷 7357-7364页

作者： Kai Xu Yujia Xu Jin Sun Xinwei Cheng Chenxi Lu Wenzhong Chen Bingfang He Tianyue Jiang School of Pharmaceutical Sciences Nanjing Tech UniversityNanjing 211816China Department of Nano Formulation Nanjing GeneLeap BiotechnologyNanjing 210061China

Messenger ribonucleic acid(mRNA)-based therapeutics hold great prospects in disease treatment and lipid nanoparticles(LNPs)are the most extensively applied non-viral platform for RNA delivery in *** the clinical success of LNPs as vehicles have been achieved,developing LNPs with enhanced mRNA transmembrane delivery and transfection efficiency in a non-toxic manner is highly desirable and *** this study,we designed a series of new ionizable amino lipids with piperazinederived headgroups and constructed a group of LNPs to promote the transfection activity of mRNA *** them,LNP formulated with lipid 10(L10-LNP)can efficiently package mRNA and perform superior transfection efficiency both in vitro and in vivo,which is mainly attributed to the improved intracellular uptake and effective endosomal *** verified that a single administration of L10-LNP packaging interleukin(IL)-12 mRNA induced tumor shrink and even regression by robust activation of immune effector CD8^(+)T cells and stimulating the generation of IFN-γwithout causing systemic toxicity,which provides a promising platform for clinical cancer immunotherapy.

关键词： ionizable lipid lipid nanoparticle piperazine-derived lipid mRNA therapeutics cancer immunotherapy

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Optimizing the Stabilization Environment of the Carbon Molecular Sieve Membranes Derived from the Porous Hollow Fibers for Gas Separation

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INDUSTRIAL & ENGINEERING CHEMISTRY research 2025年第6期64卷 3465-3472页

作者： Sheng, Lujie Mu, Qingdi Hua, Kaisheng Deng, Maicun Ren, Jizhong Chinese Acad Sci Dalian Inst Chem Phys Natl Lab Clean Energy Dalian 116023 Peoples R China

Carbon molecular sieve (CMS) hollow fiber membranes (HFMs) are very promising for efficient gas separation. However, their gas separation performance was hindered by the thick selective skin layer. In this work, defect-free CMS HFMs with a very thin selective layer (about 1.5 mu m) were prepared successfully by the pristine porous fiber precursors. Furthermore, the porous fibers were thermally pretreated in different conditions (vacuum, N2 and air) near T g of the polyimide to stabilize the structure of the HFM precursors, and the CMS membranes derived from the pretreated porous fibers exhibited attractive enhanced gas separation properties. As a result, the CMS membranes which derived from the porous hollow fibers thermally treated in vacuum and N2 exhibited the obvious enhancement of gas permeance and the comparable H2/CH4, H2/N2, CO2/CH4, CO2/N2, and O2/N2 selectivity. When they were pretreated in air condition, the H2 (242 GPU), CO2 (57 GPU), and O2 (19 GPU) permeance values increased 158%, 300%, and 405% with the slightly decreased selectivity of H2/CH4 (64), H2/N2 (53), CO2/CH4 (15.7), CO2/N2 (12.9), and O2/N2 (4.3), respectively. The thermal pretreatment of the porous HFM precursors near T g was a very facile but effective way to enhance the gas separation properties.

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Inter‑Skeleton Conductive Routes Tuning Multifunctional Conductive Foam for Electromagnetic Interference Shielding,Sensing and Thermal Management

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Nano-Micro Letters 2025年第3期17卷 19-36页

作者： Xufeng Li Chunyan Chen Zhenyang Li Peng Yi Haihan Zou Gao Deng Ming Fang Junzhe He Xin Sun Ronghai Yu Jianglan Shui Caofeng Pan Xiaofang Liu School of Materials Science and Engineering Beihang UniversityBeijing 100191People’s Republic of China Institute of Atomic Manufacturing Beihang UniversityBeijing 100191People’s Republic of China Tianmushan Laboratory Xixi Octagon CityYuhang DistrictHangzhou 310023People’s Republic of China Science and Technology On Electromagnetic Scattering Laboratory Beijing Institute of Environmental FeaturesBeijing 100854People’s Republic of China

Conductive polymer foam(CPF)with excellent compressibility and variable resistance has promising applications in electromagnetic interference(EMI)shielding and other integrated functions for wearable ***,its insufficient change amplitude of resistance with compressive strain generally leads to a degradation of shielding performance during ***,an innovative loading strategy of conductive materials on polymer foam is proposed to significantly increase the contact probability and contact area of conductive components under *** inter-skeleton conductive films are constructed by loading alginate-decorated magnetic liquid metal on the polymethacrylate films hanged between the foam skeleton(denoted as AMLM-PM foam).Traditional point contact between conductive skeletons under compression is upgraded to planar contact between conductive ***,the resistance change of AMLM-PM reaches four orders of magnitude under ***,the inter-skeleton conductive films can improve the mechanical strength of foam,prevent the leakage of liquid metal and increase the scattering area of EM ***-PM foam has strain-adaptive EMI shielding performance and shows compression-enhanced shielding effectiveness,solving the problem of traditional CPFs upon *** upgrade of resistance response also enables foam to achieve sensitive pressure sensing over a wide pressure range and compression-regulated Joule heating function.

关键词： Inter-skeleton conductive films Conductive polymer foam Liquid metal Electromagnetic interference shielding

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