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水工结构在抗洪抢险中的应用与改进

建筑与装饰 2024年第10期 58-60页

作者：刘景彦安徽水安建设集团股份有限公司安徽合肥 236000

水工结构在抗洪抢险中的应用与改进是一个关键而复杂的领域.本文通过分析水工结构的基本类型、应用、存在问题、案例分析以及改进方法,全面探讨了水工结构在应对洪水灾害中的作用.成功案例如中国南水北调中线工程展示了水工结构在实际... 详细信息

水工结构在抗洪抢险中的应用与改进是一个关键而复杂的领域.本文通过分析水工结构的基本类型、应用、存在问题、案例分析以及改进方法,全面探讨了水工结构在应对洪水灾害中的作用.成功案例如中国南水北调中线工程展示了水工结构在实际工程中的有效性,而"新奥尔良卡特里娜飓风"事件则凸显了设计缺陷和维护不足的问题.为解决这些问题,先进技术的引入、定期维护与检修以及多层次的防洪体系建设被提出作为改进水工结构的方法.

关键词：水工结构抗洪抢险实际应用改进策略

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一种柔性直流配电网保护方法

水电站机电技术 2024年第7期47卷 56-58,72页

作者：刘婧妍刘红旺国网天津城东供电公司天津300000 天津水科机电有限公司天津301900

近些年,风能、太阳能、水电等电源发展迅速,抽蓄电站进入快速建设期,促进了柔性直流配电网发展,保护装置的研究是制约直流配电网发展的瓶颈技术。本文提出一种柔性直流配电网保护方法,采用串入限流装置的方法减小故障电流,延长电容器放... 详细信息

近些年,风能、太阳能、水电等电源发展迅速,抽蓄电站进入快速建设期,促进了柔性直流配电网发展,保护装置的研究是制约直流配电网发展的瓶颈技术。本文提出一种柔性直流配电网保护方法,采用串入限流装置的方法减小故障电流,延长电容器放电时间,降低了对直流断路器的设计要求,为保护装置的动作争取了时间。同时在换流桥与出口电容之间装设快速开关,避免了故障电流对换流桥的伤害,能够与直流断路器配合及时切断故障线路。仿真结果表明限流器能够为断路器动作争取时间,利用快速开关作为控制源,用时更短,保证了经济性。研究结果可为直流配电网的安全、稳定、优化运行提供更多的理论依据。

关键词：直流配电网保护装置限流装置

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干旱胁迫下冬小麦不同品种萌发特性差异的研究

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作物学报 2024年第6期50卷 1568-1583页

作者：乔志新张杰道王雨郭启芳刘燕静陈蕊胡文浩孙爱清山东农业大学农学院/小麦育种全国重点实验室山东泰安271018 山东农业大学生命科学学院山东泰安271018

干旱是影响小麦生产的重要逆境,可以造成萌发成苗质量下降。为了解当前小麦品种在干旱胁迫下的种子萌发特性,采用沙培控水法研究了生产上应用广泛的128个小麦品种的干旱萌发特性;筛选出干旱萌发特性差异显著的6个小麦品种(山农28号(SN28... 详细信息

干旱是影响小麦生产的重要逆境,可以造成萌发成苗质量下降。为了解当前小麦品种在干旱胁迫下的种子萌发特性,采用沙培控水法研究了生产上应用广泛的128个小麦品种的干旱萌发特性;筛选出干旱萌发特性差异显著的6个小麦品种(山农28号(SN28)、长6878(C6878)、烟农19(YN19)、山农23号(SN23)、鑫麦296(XM296)和新麦38(XM38))进行干旱胁迫下种子萌发过程中的生理生化分析。结果表明,根据活力指数的耐旱系数进行聚类分析,将128个小麦品种的干旱萌发特性分为好、较好、中等、较差、差5类。山农28号和长6878等18个干旱萌发特性好的小麦品种种子萌发快,幼苗整齐健壮;新麦38、乐麦185等26个干旱萌发特性差的小麦品种种子萌发慢、萌发时间分散、发芽率低且幼苗整齐度差。进一步对不同干旱萌发特性的小麦品种进行生理生化指标测定表明,干旱萌发特性好的山农28号和长6878干旱萌发前期大分子修复基因TDP1表达水平显著高于对照;干旱萌发前期POD活性也显著高于对照;α-淀粉酶和半胱氨酸蛋白酶活性受干旱影响较小,萌发后期的可溶性蛋白含量显著高于对照。而干旱萌发特性差的鑫麦296和新麦38在干旱胁迫下种胚DNA和蛋白质修复基因表达水平上升相对滞后;在干旱胁迫下的半胱氨酸蛋白酶活性显著降低。上述结果表明,干旱萌发特性好的小麦品种在干旱胁迫下萌发成苗过程中种胚大分子修复能力和种子抗氧化能力强,贮藏物质动员早,最终种子萌发速度快,出苗质量高。

关键词：小麦干旱胁迫种子萌发特性贮藏物质分解转化大分子修复能力抗氧化能力

A benchmark-based method for evaluating hyperparameter optimization techniques of neural networks for surface water quality prediction

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Frontiers of Environmental Science & Engineering 2024年第5期18卷 13-27页

作者： Xuan Wang yan Dong jing yang Zhipeng liu Jinsuo Lu School of Environmental and Municipal Engineering Xi’an University of Architecture and TechnologyXi’an710055China Shaanxi Key Laboratory of Environmental Engineering Xi’an University of Architecture and TechnologyXi’an710055China State Key Laboratory of Green Building in West China Xi’an University of Architecture and TechnologyXi’an710055China

Neural networks(NNs)have been used extensively in surface water prediction tasks due to computing algorithm improvements and data *** essential step in developing an NN is the hyperparameter *** practice,it is common to manually determine hyperparameters in the studies of NNs in water resources *** may result in considerable randomness and require significant computation time;therefore,hyperparameter optimization(HPO)is *** study adopted five representatives of the HPO techniques in the surface water quality prediction tasks,including the grid sampling(GS),random search(RS),genetic algorithm(GA),Bayesian optimization(BO)based on the Gaussian process(GP),and the tree Parzen estimator(TPE).For the evaluation of these techniques,this study proposed a method:first,the optimal hyperparameter value sets achieved by GS were regarded as the benchmark;then,the other HPO techniques were evaluated and compared with the benchmark in convergence,optimization orientation,and consistency of the optimized *** results indicated that the TPE-based BO algorithm was recommended because it yielded stable convergence,reasonable optimization orientation,and the highest consistency rates with the benchmark *** optimization consistency rates via TPE for the hyperparameters hidden layers,hidden dimension,learning rate,and batch size were 86.7%,73.3%,73.3%,and 80.0%,*** the evaluation of HPO techniques directly based on the prediction performance of the optimized NN in a single HPO test,the proposed benchmark-based HPO evaluation approach is feasible and robust.

关键词： Neural networks Hyperparameter optimization Surface water quality prediction Bayes optimization Genetic algorithm

Carbon Dots as“On–Off–On”Fluorescence Sensors for Selective and Consecutive Detection of 4-Nitrophenol and Cerium(IV)in Water Samples

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Journal of Analysis and Testing 2024年第2期8卷 201-209页

作者： jing yang Hao liu yan Huang Li Li Huajie liu Yaping Ding Department of Chemistry College of SciencesShanghai UniversityShanghai200444China School of Chemical Science and Engineering Tongji UniversityShanghai200092China

An“on–off–on”fluorescence sensor was designed for rapidly and consecutively detecting 4-nitrophenol and cerium(IV)without the use of any labeling *** yellow carbon dots were synthesized by a simple one-step hydrothermal approach,and various techniques were applied to investigate the morphology,structure,and optical properties of the carbon *** the optimal experimental conditions,4-nitrophenol rapidly quenched the fluorescence of carbon dots as a result of the inner filter eff ect(IFE).The fluorescence intensity of carbon dots was linear with the concentration of 4-nitrophenol(1–150μmol/L)and the limit of detection was 0.32μmol/*** fluorescence was gradually recovered as the cerium(IV)concentration(0.5–100μmol/L)increased in CDs/4-NP,and the limit of detection was 0.16μmol/*** sensor showed good selectivity and demonstrated high accuracy for the analysis of 4-nitrophenol and cerium(IV)in actual water samples.

关键词： Carbon dots Fluorescence sensor 4-Nitrophenol Cerium(IV) Water samples

Predicting submerged vegetation drag with a machine learning-based method

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Journal of Hydrodynamics 2024年第3期36卷 534-545页

作者： Meng-yang liu Hong-wu Tang Sai-yu Yuan jing yan College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing210098China Key Laboratory of Hydrologic-Cycle and Hydrodynamic-System of Ministry of Water Resources Hohai UniversityNanjing210098China

Accurate estimation of the drag forces generated by vegetation stems is crucial for the comprehensive assessment of the impact of aquatic vegetation on hydrodynamic processes in aquatic *** coupling relationship between vegetation layer flow velocity and vegetation drag makes precise prediction of submerged vegetation drag forces particularly *** present study utilized published data on submerged vegetation drag force measurements and employed a genetic programming(GP)algorithm,a machine learning technique,to establish the connection between submerged vegetation drag forces and flow and vegetation *** using the bulk velocity,U,as the reference velocity scale to define the drag coefficient,C_(d),and stem Reynolds number,the GP runs revealed that the drag coefficient of submerged vegetation is related to submergence ratio(H^(*)),aspect ratio(d^(*)),blockage ratio(ψ^(*)),and vegetation density(λ).The relation between vegetation stem drag forces and flow velocity is implicitly embedded in the definition of C_(d).Comparisons with experimental drag force measurements indicate that using the bulk velocity as the reference velocity,as opposed to using the vegetation layer average velocity,U_(v),eliminates the need for complex iterative processes to estimate U_(v)and avoids introducing additional errors associated with U_(v)*** approach significantly enhances the model’s predictive capabilities and results in a simpler and more user-friendly formula expression.

关键词： Drag coefficient genetic programming algorithm submerged vegetation flow resistance cylinder array

A buffer overflow detection and defense method based on RiSC-V instruction set extension

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Cybersecurity 2024年第2期7卷 28-43页

作者： Chang liu yan-Jun Wu jing-Zheng Wu Chen Zhao Intelligent Software Research Center Institute of SoftwareChinese Academy of SciencesBejingChina University of Chinese Academy of Sciences BeijingChina State Key Laboratory of Computer Science Institute of SoftwareChinese Academy of SciencesBeijingChina

Buffer overflow poses a serious threat to the memory security of modern operating *** overwrites the con-tents of other memory areas by breaking through the buffer capacity limit,destroys the system execution environ-ment,and provides implementation space for various system attacks such as program control flow *** makes it a wide range of harms.A variety of security technologies have been proposed to deal with system security problems including buffer *** example,No eXecute(NX for short)is a memory management technology commonly used in Harvard *** can refuse the execution of code which residing in a specific memory,and can effectively suppress the abnormal impact of buffer overflow on control ***,in recent years,it has also been used in the field of system security,deriving a series of solutions based on NX technology,such as ExecShield,DEP,StackGuard,***,these security solutions often rely too much on the processor archi-tecture so that the protection coverage is insufficient and the accuracy is *** in the emerging system architecture field represented by RiSC-V,there is still a lack of effective solutions for buffer overflow *** the continuous rapid development of the system architecture,it is urgent to develop defense methods that are applicable to different system application environments and oriented to all executable memory spaces to meet the needs of system security ***,we propose BOP,A new system memory security design method based on RISC-V extended instructions,to build a RISC-V buffer overflow detection and defense system and deal with the buffer overflow threat in *** to this method,NX technology can be combined with program control flow analysis,and Nx bit mechanism can be used to manage the executability of memory space,so as to achieve a more granular detection and defense of buffer overflow attacks that may occur in RISC-V system

关键词： RISc-V Operating system security Buffer overflow Control flow hijacking Nx bit Xibop

Three dimensional velocity model and its tectonic implications at China Seismic Experimental Site,eastern margin of the Tibetan Plateau

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Science China Earth Sciences 2024年第7期67卷 2268-2290页

作者： Jianping WU yan CAI Wei WANG Weilai WANG Changzai WANG Lihua FANG yaning liu jing liu Institute of Geophysics China Earthquake AdministrationBeijing 100081China Beijing Baijiatuan Earth Science National Observation and Research Station Beijing 1095China Beijing Earthquake Agency Beijing 100080China

The China Seismic Experimental Site(CSES)is located at the intersection of the Tibetan Plateau,South China Block,and Indian Plate and has complex geological settings and intense crustal deformation,making it one of the most seismically active areas in Chinese mainland.A high-resolution,three-dimensional(3D)crust-mantle velocity structure is crucial for understanding seismotectonic environments,lithospheric deformation mechanisms,and deep dynamic *** first constructed a high-vertical-resolution 3D initial velocity model using the joint inversion of receiver functions and surface waves and then obtained a 3D P-and S-wave velocity model(CSES-VM1.0)with the highest lateral resolution of 0.25°for the CSES using double-difference *** to the limitations of the Sn observation data,the resolution of the S-wave velocity model in the lower crust and upper mantle was reduced,making it closer to the initial model provided by joint inversion.A comparison with explosive-source seismic data showed that the synthetic P-wave first-arrival travel times of the new model were closer to the observations than those of the previous velocity *** velocity cross-sections across the source areas of the 2022 Lushan MS6.1 and Ludian MS6.8 earthquakes reveal that the former earthquake occurred near a weak contact zone between the Tibetan Plateau and Sichuan Basin,and the rupture of the latter earthquake occurred in a granitic area,with the northern end blocked by rigid high-velocity bodies.A clear high-velocity anomaly zone is distributed along the western margin of the yangtze Block,revealing the spatial distribution of Neoproterozoic intermediate-basic *** high-velocity zone significantly controls the morphology of fault zones and influences the rupture processes of major *** northeast-southwest and north-south trending high-velocity anomalies were found near Panzhihua,potentially related to Neoproterozoic and Middle-Late Permian intermediate

关键词： Eastern Tibetan Plateau China Seismic Experimental Site yangtze Block Velocity model Double-difference tomography

Microphase Separation of Semiflexible Ring Diblock Copolymers

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Chinese Journal of Polymer Science 2024年第2期42卷 267-276,I0011页

作者： Dan-yan Qin Sheng-Da Zhao Zhi-Xin liu jing Zhang Xing-Hua Zhang School of Physical Science and Engineering Beijing Jiaotong UniversityBeijing100044China

Aiming at the difficult problem of solving the conformation statistics of complex polymers, this study presents a novel and concise conformation statistics theoretical approach based on Monte Carlo and Neural Network method. This method offers a new research idea for investigating the conformation statistics of complex polymers, characterized by its simplicity and practicality. It can be applied to more complex topological structure, more higher degree of freedom polymer systems with higher dimensions, theory research on dynamic self-consistent field theory and polymer field theory, as well as the analysis of scattering experimental data. The conformation statistics of complex polymers determine the structure and response properties of the system. Using the new method proposed in this study, taking the semiflexible ring diblock copolymer as an example, Monte Carlo simulation is used to sample this ring conformation to construct the dataset of polymer. The structure factor describing conformation statistics are expressed as continuous functions of structure parameters by neural network supervised learning. This is the innovation of this work. As an application, the structure factors represented by neural networks were introduced into the random phase approximation theory to study the microphase separation of semiflexible ring diblock copolymers. The influence of the ring's topological properties on the phase transition behavior was pointed out.

关键词： Ring copolymer Diblock copolymers Semiflexible The order-disorder transition