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Using Pearson’s System of Curves to Approximate the Distributions of the Difference between Two Correlated Estimates of Signal-to-Noise Ratios: The Cases of Bivariate Normal and Bivariate Lognormal Distributions
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作者 Mohamed M. Shoukri 《Open Journal of Statistics》 2024年第3期207-227,共21页
Background: The signal-to-noise ratio (SNR) is recognized as an index of measurements reproducibility. We derive the maximum likelihood estimators of SNR and discuss confidence interval construction on the difference ... Background: The signal-to-noise ratio (SNR) is recognized as an index of measurements reproducibility. We derive the maximum likelihood estimators of SNR and discuss confidence interval construction on the difference between two correlated SNRs when the readings are from bivariate normal and bivariate lognormal distribution. We use the Pearsons system of curves to approximate the difference between the two estimates and use the bootstrap methods to validate the approximate distributions of the statistic of interest. Methods: The paper uses the delta method to find the first four central moments, and hence the skewness and kurtosis which are important in the determination of the parameters of the Pearsons distribution. Results: The approach is illustrated in two examples;one from veterinary microbiology and food safety data and the other on data from clinical medicine. We derived the four central moments of the target statistics, together with the bootstrap method to evaluate the parameters of Pearsons distribution. The fitted Pearsons curves of Types I and II were recommended based on the available data. The R-codes are also provided to be readily used by the readers. 展开更多
关键词 Signal-to-noise Ratio Bivariate Distributions Bootstrap Methods Delta Method Pearson System of curves
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The Effectiveness of the Havriliak-Negami Model in Predicting the Master Curves of the Asphalt Blends with SBS Triblock Copolymer and Organic-Montmorillonite at Different Temperatures and Frequencies
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作者 María Ángeles Vargas-Hernández Miguel Ángel Vargas +1 位作者 Pedro R. García-Morán Humberto Vázquez-Torres 《Journal of Materials Science and Chemical Engineering》 2024年第7期23-39,共17页
The dynamic viscoelastic properties of asphalt AC-20 and its composites with Organic-Montmorillonite clay (OMMt) and SBS were modeled using the empirical Havriliak-Negami (HN) model, based on linear viscoelastic theor... The dynamic viscoelastic properties of asphalt AC-20 and its composites with Organic-Montmorillonite clay (OMMt) and SBS were modeled using the empirical Havriliak-Negami (HN) model, based on linear viscoelastic theory (LVE). The HN parameters, α, β, G0, G∞and τHN were determined by solving the HN equation across various temperatures and frequencies. The HN model successfully predicted the rheological behavior of the asphalt and its blends within the temperature range of 25˚C - 40˚C. However, deviations occurred between 40˚C - 75˚C, where the glass transition temperature Tg of the asphalt components and the SBS polymer are located, rendering the HN model ineffective for predicting the dynamic viscoelastic properties of composites containing OMMt under these conditions. Yet, the prediction error of the HN model dropped to 2.28% - 2.81% for asphalt and its mixtures at 100˚C, a temperature exceeding the Tg values of both polymer and asphalt, where the mixtures exhibited a liquid-like behavior. The exponent α and the relaxation time increased with temperature across all systems. Incorporating OMMt clay into the asphalt blends significantly enhanced the relaxation dynamics of the resulting composites. 展开更多
关键词 ASPHALT BLENDS Master curve Linear Viscoelasticity Havriliak-negami Model
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A comparative study of data-driven battery capacity estimation based on partial charging curves 被引量:1
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作者 Chuanping Lin Jun Xu +5 位作者 Delong Jiang Jiayang Hou Ying Liang Xianggong Zhang Enhu Li Xuesong Mei 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第1期409-420,I0010,共13页
With its generality and practicality, the combination of partial charging curves and machine learning(ML) for battery capacity estimation has attracted widespread attention. However, a clear classification,fair compar... With its generality and practicality, the combination of partial charging curves and machine learning(ML) for battery capacity estimation has attracted widespread attention. However, a clear classification,fair comparison, and performance rationalization of these methods are lacking, due to the scattered existing studies. To address these issues, we develop 20 capacity estimation methods from three perspectives:charging sequence construction, input forms, and ML models. 22,582 charging curves are generated from 44 cells with different battery chemistry and operating conditions to validate the performance. Through comprehensive and unbiased comparison, the long short-term memory(LSTM) based neural network exhibits the best accuracy and robustness. Across all 6503 tested samples, the mean absolute percentage error(MAPE) for capacity estimation using LSTM is 0.61%, with a maximum error of only 3.94%. Even with the addition of 3 m V voltage noise or the extension of sampling intervals to 60 s, the average MAPE remains below 2%. Furthermore, the charging sequences are provided with physical explanations related to battery degradation to enhance confidence in their application. Recommendations for using other competitive methods are also presented. This work provides valuable insights and guidance for estimating battery capacity based on partial charging curves. 展开更多
关键词 Lithium-ion battery Partial charging curves Capacity estimation DATA-DRIVEN Sampling frequency
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Method for determining the position of landslide slip-surface with a typical inclinometric curves
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作者 CHEN Hao WU Hong-gang 《Journal of Mountain Science》 SCIE CSCD 2024年第2期413-432,共20页
In the actual monitoring of deep hole displacement,the identification of slip surfaces is primarily based on abrupt changes observed in the inclinometric curve.In conventional identification methods,inclinometric curv... In the actual monitoring of deep hole displacement,the identification of slip surfaces is primarily based on abrupt changes observed in the inclinometric curve.In conventional identification methods,inclinometric curves exhibiting indications of sliding can be categorized into three types:B-type,D-type,and r-type.The position of the slip surface is typically determined by identifying the depth corresponding to the point of maximum displacement mutation.However,this method is sensitive to the interval of measurement points and the observation scale of the coordinate axes and suffers from unclear sliding surfaces and uncertain values.Based on the variation characteristics of these diagonal curves,we classified the landslide into three components:the sliding body,the sliding interval,and the immobile body.Moreover,three different generalization models were established to analyze the relationships between the curve form and the slip surface location based on different physical indicators such as displacement rate,relative displacement,and acceleration.The results show that the displacement rate curves of an r-type slope exhibit a clustering feature in the sliding interval,and by solving for the depth of discrete points within the step phase,it is possible to determine the location of the slip surface.On the other hand,D-type slopes have inflection points in the relative displacement curve located at the slip surface.The acceleration curves of B-type slopes exhibit clustering characteristics during the sliding interval,while the scattered acceleration data demonstrate wandering characteristics.Consequently,the slip surface location can be revealed by solving the depth corresponding to the maximum acceleration with cubic spline interpolation.The approach proposed in this paper was applied to the monitoring data of a landslide in Yunnan Province,China.The results indicate that our approach can accurately identify the slip surface location and enable computability of its position,thereby enhancing applicability and reliability of the deep-hole displacement monitoring data. 展开更多
关键词 Inclinometric curve Slip-surface position Displacement rate Relative displacement Acceleration
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Analytical Determination of Size and Location of Roadside Horizontal Sightline Offsets for Compound Curves
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作者 Timur Mauga 《Journal of Transportation Technologies》 2024年第1期119-135,共17页
AASHTO’s guideline for geometric design of highways and similar guidelines require that roadside areas on the inside of horizontal curves be cleared of high objects to provide stopping sight distance. The guidelines ... AASHTO’s guideline for geometric design of highways and similar guidelines require that roadside areas on the inside of horizontal curves be cleared of high objects to provide stopping sight distance. The guidelines have analytical models for determining the extent of clearance, known as the horizontal sightline offset or clearance offset, for simple curves. Researchers in the past have developed analytical models for clearance offsets for spiraled and reverse curves. Very few researchers developed analytical models for available sight distances for compound curves. Still missing are models for horizontal sightline offsets and locations of the offsets for compound curves. The objective of this paper is to present development of analytical models and charts for determining horizontal sightline offsets and their locations for compound curves. The paper considers curves whose component arcs are individually shorter than stopping sight distance. The resulting models and the charts have been verified with accurate values determined using graphical methods. The models and the charts will find application in geometric design of highway compound curves. 展开更多
关键词 Sight Distance Roadside Clearance Offsets Compound curves
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Sensitive Information Security Based on Elliptic Curves
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作者 Nadine Nibigira Vincent Havyarimana Zhu Xiao 《World Journal of Engineering and Technology》 2024年第2期274-285,共12页
The elliptic curve cryptography algorithm represents a major advancement in the field of computer security. This innovative algorithm uses elliptic curves to encrypt and secure data, providing an exceptional level of ... The elliptic curve cryptography algorithm represents a major advancement in the field of computer security. This innovative algorithm uses elliptic curves to encrypt and secure data, providing an exceptional level of security while optimizing the efficiency of computer resources. This study focuses on how elliptic curves cryptography helps to protect sensitive data. Text is encrypted using the elliptic curve technique because it provides great security with a smaller key on devices with limited resources, such as mobile phones. The elliptic curves cryptography of this study is better than using a 256-bit RSA key. To achieve equivalent protection by using the elliptic curves cryptography, several Python libraries such as cryptography, pycryptodome, pyQt5, secp256k1, etc. were used. These technologies are used to develop a software based on elliptic curves. If built, the software helps to encrypt and decrypt data such as a text messages and it offers the authentication for the communication. 展开更多
关键词 CRYPTOGRAPHY Elliptic curves Digital Security Data Sensitive Data IMPLEMENTATION
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Review on Service Curves of Typical Scheduling Algorithms
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作者 GAO Yuehong NING Zhi +4 位作者 HE Jia ZHOU Jinfei GAO Chenqiang TANG Qingkun YU Jinghai 《ZTE Communications》 2024年第2期55-70,共16页
In recent years,various internet architectures,such as Integrated Services(IntServ),Differentiated Services(DiffServ),Time Sensitive Networking(TSN)and Deterministic Networking(DetNet),have been proposed to meet the q... In recent years,various internet architectures,such as Integrated Services(IntServ),Differentiated Services(DiffServ),Time Sensitive Networking(TSN)and Deterministic Networking(DetNet),have been proposed to meet the quality-of-service(QoS)requirements of different network services.Concurrently,network calculus has found widespread application in network modeling and QoS analysis.Network calculus abstracts the details of how nodes or networks process data packets using the concept of service curves.This paper summarizes the service curves for typical scheduling algorithms,including Strict Priority(SP),Round Robin(RR),Cycling Queuing and Forwarding(CQF),Time Aware Shaper(TAS),Credit Based Shaper(CBS),and Asynchronous Traffic Shaper(ATS).It introduces the theory of network calculus and then provides an overview of various scheduling algorithms and their associated service curves.The delay bound analysis for different scheduling algorithms in specific scenarios is also conducted for more insights. 展开更多
关键词 network calculus service curve scheduling algorithm QOS
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Gaussian Distance Weighted Algorithm for Geometric Characteristics of Three-Dimensional Discrete Curves
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作者 Liyan Zhang Haiyi Ai +3 位作者 Shaohong Yan Haili Chen Jiali Zou Junqing Zhang 《Journal of Applied Mathematics and Physics》 2024年第10期3599-3612,共14页
Discrete curves are composed of a set of ordered discrete points distributed at the intersection of the scanning plane and the surface of the object. In order to accurately calculate the geometric characteristics of a... Discrete curves are composed of a set of ordered discrete points distributed at the intersection of the scanning plane and the surface of the object. In order to accurately calculate the geometric characteristics of any point on the discrete curve, a distance-based Gaussian weighted algorithm is proposed to estimate the geometric characteristics of three-dimensional space discrete curves. According to the definition of discrete derivatives, the algorithm fully considers the relative position difference between a specific point and its neighboring points, introduces the distance weighting idea, and integrates the smoothing strategy. The experiment uses two spatial discrete curves for uniform and non-uniform sampling, and compares them with two commonly used estimation algorithms. The comparative analysis is carried out in terms of sampling density, neighborhood radius and noise resistance. The experimental results show that the Gaussian distance weighted algorithm is effective and provides an efficient algorithm for underground pipeline safety detection. 展开更多
关键词 Discrete curve Angle Weight Algorithm Comparison Underground Pipeline Inspection
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Magnetic Field Curves and Magnetic Equipotential Surfaces around Crossing Electrical Wires Replacing Classical Magnetic Field Lines
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作者 Geoffroy Auvert 《Open Journal of Applied Sciences》 2024年第8期1996-2008,共13页
This article is based on a recent model specifically defining magnetic field values around electrical wires. With this model, calculations of field around parallel wires were obtained. Now, this model is extended with... This article is based on a recent model specifically defining magnetic field values around electrical wires. With this model, calculations of field around parallel wires were obtained. Now, this model is extended with the new concept of magnetic equipotential surface to magnetic field curves around crossing wires. Cases of single, double, and triple wires are described. Subsequent article will be conducted for more general scenarios where wires are neither infinite nor parallel. 展开更多
关键词 Magnetic Field Value Magnetic Field Vector Magnetic Field Line Magnetic Field curve Equipotential Surface Crossing Electrical Wires Magnetic Cross Product
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The Origin of the Flat Rotation Curves in Spiral Galaxies: The Hidden Roles of Glitching SMDEOs and Emission of Gravitational Waves
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作者 Ahmad A. Hujeirat Peter Berczik 《Journal of Modern Physics》 2024年第10期1523-1542,共20页
Supermassive DEOs (SMDEOs) are cosmologically evolved objects made of irreducible incompressible supranuclear dense superfluids: The state we consider to govern the matter inside the cores of massive neutron stars. Th... Supermassive DEOs (SMDEOs) are cosmologically evolved objects made of irreducible incompressible supranuclear dense superfluids: The state we consider to govern the matter inside the cores of massive neutron stars. These cores are practically trapped in false vacua, rendering their detection by outside observers impossible. Based on massive parallel computations and theoretical investigations, we show that SMDEOs at the centres of spiral galaxies that are surrounded by massive rotating torii of normal matter may serve as powerful sources for gravitational waves carrying away roughly 1042 erg/s. Due to the extensive cooling by GWs, the SMDEO-Torus systems undergo glitching, through which both rotational and gravitational energies are abruptly ejected into the ambient media, during which the topologies of the embedding spacetimes change from curved into flatter ones, thereby triggering a burst gravitational energy of order 1059 erg. Also, the effects of glitches found to alter the force balance of objects in the Lagrangian-L1 region between the central SMDEO-Torus system and the bulge, enforcing the enclosed objects to develop violent motions, that may explain the origin of the rotational curve irregularities observed in the innermost part of spiral galaxies. Our study shows that the generated GWs at the centres of galaxies, which traverse billions of objects during their outward propagations throughout the entire galaxy, lose energy due to repeatedly squeezing and stretching the objects. Here, we find that these interactions may serve as damping processes that give rise to the formation of collective forces f∝m(r)/r, that point outward, endowing the objects with the observed flat rotation curves. Our approach predicts a correlation between the baryonic mass and the rotation velocities in galaxies, which is in line with the Tully-Fisher relation. The here-presented self-consistent approach explains nicely the observed rotation curves without invoking dark matter or modifying Newtonian gravitation in the low-field approximation. 展开更多
关键词 General Relativity: Black Holes Neutron Stars Quantum Fields: QCD Condensed Matter INCOMPRESSIBILITY SUPERFLUIDITY Cosmology: Galaxy Formation Spiral Galaxies Dark Matter Rotation curves
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瞬时NH_(4)^(+)-N冲击对SBR系统污染物去除的影响
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作者 王帆 肖乐天 +3 位作者 艾胜书 蒋维卿 刘轩彤 边德军 《水处理技术》 CAS CSCD 北大核心 2024年第2期105-110,共6页
探究了瞬时NH_(4)^(+)-N冲击对SBR系统污染物去除效果的影响,在反应运行的第19、33、45天,通过提高单周期瞬时NH_(4)^(+)-N质量浓度至41.05、60.02、80.15 mg/L,对SBR系统进行冲击。结果表明,进水NH4+-N质量浓度从41.05 mg/L增加到80.15... 探究了瞬时NH_(4)^(+)-N冲击对SBR系统污染物去除效果的影响,在反应运行的第19、33、45天,通过提高单周期瞬时NH_(4)^(+)-N质量浓度至41.05、60.02、80.15 mg/L,对SBR系统进行冲击。结果表明,进水NH4+-N质量浓度从41.05 mg/L增加到80.15 mg/L时,COD、TP、NH_(4)^(+)-N去除效果没有明显变化,TN出水质量浓度从10.25 mg/L增加到21.49 mg/L,TN的出水变高主要受碳源不足的影响。三次瞬时NH4+-N冲击负荷下,NH4+-N降解速率基本不变。三次瞬时NH_(4)^(+)-N冲击负荷下,SBR系统中EPS总量对比常负荷运行时,均有所提高,且PN的含量在增加,PS的含量先升高后降低。而PN和PS含量的变化,在一定程度上会对活性污泥的絮凝造成影响,导致活性污泥粒径逐渐减少。系统在受到瞬时NH_(4)^(+)-N冲击后,TN出水会有所提高,但是经过一个周期的运行便可以恢复。 展开更多
关键词 SBR反应器 NH_(4)^(+)-n浓度 瞬时冲击 EPS 粒度粒径
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基于断裂力学的腐蚀钢丝疲劳S-N曲线研究 被引量:1
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作者 叶华文 叶杨帆 +2 位作者 邓雪峰 杨军川 徐勋 《铁道科学与工程学报》 EI CAS CSCD 北大核心 2024年第5期1990-2000,共11页
高强冷拔钢丝因其优异的力学性能被广泛应用于缆索承重结构,服役过程中钢丝腐蚀与断裂威胁着结构安全。钢丝腐蚀后表面的蚀坑因应力集中效应易产生疲劳裂纹,因此腐蚀钢丝剩余疲劳寿命主要取决于裂纹的扩展阶段,且裂纹扩展受到腐蚀程度(... 高强冷拔钢丝因其优异的力学性能被广泛应用于缆索承重结构,服役过程中钢丝腐蚀与断裂威胁着结构安全。钢丝腐蚀后表面的蚀坑因应力集中效应易产生疲劳裂纹,因此腐蚀钢丝剩余疲劳寿命主要取决于裂纹的扩展阶段,且裂纹扩展受到腐蚀程度(初始损伤)的显著影响。精确表征腐蚀程度并准确评估服役期钢丝腐蚀后的剩余寿命,仍是亟待解决的维修难题。首先采用蚀坑最大深度表征钢丝腐蚀程度,以应力强度因子幅作为裂纹扩展驱动力指标,基于断裂力学的Paris公式建立受拉钢丝裂纹扩展理论模型,进而推导腐蚀钢丝的疲劳S-N曲线。大量既有的腐蚀钢丝疲劳试验结果与理论预测值的比较验证了所提理论模型及疲劳S-N曲线的合理性和有效性。含多个蚀坑的钢丝裂纹扩展有限元模拟表明,等效单裂纹适用于多腐蚀坑钢丝疲劳寿命的简化分析。参数分析表明,蚀坑深度和腐蚀环境是腐蚀钢丝疲劳强度的关键影响因素,而应力比和疲劳加载频率影响较小,所提出的S-N曲线在钢丝常规服役条件下适用于评估其剩余寿命,可得到合理的预测结果。基于断裂力学所提的理论方法和疲劳S-N曲线可为腐蚀钢丝的疲劳强度和寿命评估提供参考。 展开更多
关键词 冷拔钢丝 腐蚀 剩余寿命 S-n曲线 蚀坑深度
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Characterization of the generalized permeability jail in tight reservoirs by analyzing relative-permeability curves and numerical simulation 被引量:1
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作者 Feng-Peng Lai Zhi-Ping Li +1 位作者 He-Xin Wei Wei Zhang 《Petroleum Science》 SCIE EI CSCD 2023年第5期2939-2950,共12页
This study comprehensively characterizes the boundary values of generalized permeability jail in tight reservoirs through relative-permeability curve analysis,numerical simulation,and economic evaluation.A total numbe... This study comprehensively characterizes the boundary values of generalized permeability jail in tight reservoirs through relative-permeability curve analysis,numerical simulation,and economic evaluation.A total number of 108 relative-permeability curves of rock samples from tight reservoirs were obtained,and the characteristics of relative-permeability curves were analyzed.The irreducible water saturation(Swi)mainly ranges from 20% to 70%,and the residual gas saturation(Sgr)ranges from 5% to 15% for 55% of the samples.The relative-permeability curves are categorized into six types(Category-Ⅰ to Ⅵ)by analyzing the following characteristics:The relative permeability of gas at Swi,the relative permeability of water at Sgr,and the relative permeability corresponding to the isotonic point.The relative permeability curves were normalized to facilitate numerical simulation and evaluate the impact of different types of curves on production performance.The results of simulation show significant difference in production performance for different types of relative-permeability curves:Category-Ⅰ corresponds to the case with best well performance,whereas Categories-Ⅴ and Ⅵ correspond to the cases with least production volume.The results of economic evaluation show a generalized permeability jail for Categories-Ⅳ,Ⅴ,and Ⅵ,and the permeability jail develops when the relative permeability of gas and water is below 0.06.This study further quantifies the range of micro-pore parameters corresponding to the generalized permeability jail for a tight sandstone reservoir. 展开更多
关键词 Generalized permeability jail CHARACTERIZATION Relative permeability curve Numerical simulation Pore structure
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海水养殖尾水中NH_(4)^(+)-N去除技术的机理与工艺研究进展 被引量:1
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作者 赵伟华 王艳艳 +3 位作者 苏少卿 邱浩杰 王凯 张勇 《水处理技术》 CAS CSCD 北大核心 2024年第5期1-5,共5页
总结了海水养殖尾水中NH_(4)^(+)-N的来源及特点,NH_(4)^(+)-N去除技术的机理与功能微生物、工艺应用及其微生物分布等,重点对海水养殖尾水中NH_(4)^(+)-N去除技术的机理与工艺应用进行了阐述。好氧氨氧化微生物主要包括氨氧化细菌(AOB... 总结了海水养殖尾水中NH_(4)^(+)-N的来源及特点,NH_(4)^(+)-N去除技术的机理与功能微生物、工艺应用及其微生物分布等,重点对海水养殖尾水中NH_(4)^(+)-N去除技术的机理与工艺应用进行了阐述。好氧氨氧化微生物主要包括氨氧化细菌(AOB)、氨氧化古菌(AOA)及全程硝化菌(comammox),厌氧氨氧化微生物主要包括厌氧氨氧化细菌(AnAOB)。基于好氧氨氧化微生物原理去除NH_(4)^(+)-N的主要工艺技术包括移动床生物膜反应器(MBBR)、曝气生物滤池(BAF)、人工湿地和生态塘等;基于厌氧氨氧化菌处理海水养殖尾水的主要工艺技术有厌氧流化床、厌氧固定床等。指出工艺应用与微生物种群结构之间关系的研究不足。富集氨氧化微生物从而实现经济高效脱氮是未来工艺研究的重点方向。 展开更多
关键词 海水养殖尾水 NH_(4)^(+)-n去除 氨氧化微生物 生物膜法 生态处理
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Reconstruction of probabilistic S-N curves under fatigue life following lognormal distribution with given confidence 被引量:2
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作者 赵永翔 杨冰 彭佳纯 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2007年第4期455-460,共6页
When the historic probabilistic S-N curves are given under special survival probability and confidence levels and there is no possible to re-test, fatigue reliability analysis at other levels can not be done except fo... When the historic probabilistic S-N curves are given under special survival probability and confidence levels and there is no possible to re-test, fatigue reliability analysis at other levels can not be done except for the special levels. Therefore, the wide applied curves are expected. Monte Carlo reconstruction methods of the test data and the curves are investigated under fatigue life following lognormal distribution. To overcome the non-conservative assessment of existent man-made enlarging the sample size up to thousands, a simulation policy is employed to address the true production where the sample size is controlled less than 20 for material specimens, 10 for structural component specimens and the errors matching the statistical parameters are less than 5 percent. Availability and feasibility of the present methods have been indicated by the reconstruction practice of the test data and curves for 60Si2Mn high strength spring steel of railway industry. 展开更多
关键词 FATIGUE probabilistic S-n curves RECONSTRUCTION Monte Carlo simulation
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Inverse design of mechanical metamaterial achieving a prescribedconstitutive curve 被引量:1
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作者 Zongliang Du Tanghuai Bian +4 位作者 Xiaoqiang Ren Yibo Jia Shan Tang Tianchen Cui Xu Guo 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2024年第1期16-22,共7页
Besides exhibiting excellent capabilities such as energy absorption,phase-transforming metamaterials offer a vast design space for achieving nonlinear constitutive relations.This is facilitated by switching between di... Besides exhibiting excellent capabilities such as energy absorption,phase-transforming metamaterials offer a vast design space for achieving nonlinear constitutive relations.This is facilitated by switching between different patterns under deformation.However,the related inverse design problem is quite challenging,due to the lack of appropriate mathematical formulation and the convergence issue in the post-buckling analysis of intermediate designs.In this work,periodic unit cells are explicitly described by the moving morphable voids method and effectively analyzed by eliminating the degrees of freedom in void regions.Furthermore,by exploring the Pareto frontiers between error and cost,an inverse design formulation is proposed for unit cells.This formulation aims to achieve a prescribed constitutive curve and is validated through numerical examples and experimental results.The design approach presented here can be extended to the inverse design of other types of mechanical metamaterials with prescribed nonlinear effective properties. 展开更多
关键词 METAMATERIAL Pattern-transformation Constitutive curve Inverse design
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A Novel Contour Tracing Algorithm for Object Shape Reconstruction Using Parametric Curves
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作者 Nihat Arslan Kali Gurkahraman 《Computers, Materials & Continua》 SCIE EI 2023年第4期331-350,共20页
Parametric curves such as Bézier and B-splines, originally developedfor the design of automobile bodies, are now also used in image processing andcomputer vision. For example, reconstructing an object shape in an... Parametric curves such as Bézier and B-splines, originally developedfor the design of automobile bodies, are now also used in image processing andcomputer vision. For example, reconstructing an object shape in an image,including different translations, scales, and orientations, can be performedusing these parametric curves. For this, Bézier and B-spline curves can be generatedusing a point set that belongs to the outer boundary of the object. Theresulting object shape can be used in computer vision fields, such as searchingand segmentation methods and training machine learning algorithms. Theprerequisite for reconstructing the shape with parametric curves is to obtainsequentially the points in the point set. In this study, a novel algorithm hasbeen developed that sequentially obtains the pixel locations constituting theouter boundary of the object. The proposed algorithm, unlike the methods inthe literature, is implemented using a filter containing weights and an outercircle surrounding the object. In a binary format image, the starting point ofthe tracing is determined using the outer circle, and the next tracing movementand the pixel to be labeled as the boundary point is found by the filter weights.Then, control points that define the curve shape are selected by reducing thenumber of sequential points. Thus, the Bézier and B-spline curve equationsdescribing the shape are obtained using these points. In addition, differenttranslations, scales, and rotations of the object shape are easily provided bychanging the positions of the control points. It has also been shown that themissing part of the object can be completed thanks to the parametric curves. 展开更多
关键词 Contour tracing algorithm bézier curve B-spline curve object shape reconstruction
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A dynamic soil freezing characteristic curve model for frozen soil 被引量:1
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作者 Xiaokang Li Xu Li Jiankun Liu 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第8期3339-3352,共14页
The soil freezing characteristic curve(SFCC)plays a fundamental role in comprehending thermohydraulic behavior and numerical simulation of frozen soil.This study proposes a dynamic model to uniformly express SFCCs ami... The soil freezing characteristic curve(SFCC)plays a fundamental role in comprehending thermohydraulic behavior and numerical simulation of frozen soil.This study proposes a dynamic model to uniformly express SFCCs amidst varying total water contents throughout the freezing-thawing process.Firstly,a general model is proposed,wherein the unfrozen water content at arbitrary temperature is determined as the lesser of the current total water content and the reference value derived from saturated SFCC.The dynamic performance of this model is verified through test data.Subsequently,in accordance with electric double layer(EDL)theory,the theoretical residual and minimum temperatures in SFCC are calculated to be-14.5℃to-20℃for clay particles and-260℃,respectively.To ensure that the SFCC curve ends at minimum temperature,a correction function is introduced into the general model.Furthermore,a simplified dynamic model is proposed and investigated,necessitating only three parameters inherited from the general model.Additionally,both general and simplified models are evaluated based on a test database and proven to fit the test data exactly across the entire temperature range.Typical recommended parameter values for various types of soils are summarized.Overall,this study provides not only a theoretical basis for most empirical equations but also proposes a new and more general equation to describe the SFCC. 展开更多
关键词 Frozen soils Unsaturated soils Soil freezing characteristic curve(SFCC) Mathematic models
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Investigation of magnetization reversal and domain structures in perpendicular synthetic antiferromagnets by first-order reversal curves and magneto-optical Kerr effect
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作者 王向谦 李佳楠 +2 位作者 何开宙 谢明玲 朱旭鹏 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第11期580-584,共5页
Perpendicular synthetic-antiferromagnet(p-SAF) has broad applications in spin-transfer-torque magnetic random access memory and magnetic sensors. In this study, the p-SAF films consisting of (Co/Ni)3]/Ir(tIr)/[(Ni/Co)... Perpendicular synthetic-antiferromagnet(p-SAF) has broad applications in spin-transfer-torque magnetic random access memory and magnetic sensors. In this study, the p-SAF films consisting of (Co/Ni)3]/Ir(tIr)/[(Ni/Co)3are fabricated by magnetron sputtering technology. We study the domain structure and switching field distribution in p-SAF by changing the thickness of the infrared space layer. The strongest exchange coupling field(Hex) is observed when the thickness of Ir layer(tIr) is 0.7 nm and becoming weak according to the Ruderman–Kittel–Kasuya–Yosida-type coupling at 1.05 nm,2.1 nm, 4.55 nm, and 4.9 nm in sequence. Furthermore, the domain switching process between the upper Co/Ni stack and the bottom Co/Ni stack is different because of the antiferromagnet coupling. Compared with ferromagnet coupling films, the antiferromagnet samples possess three irreversible reversal regions in the first-order reversal curve distribution.With tIrincreasing, these irreversible reversal regions become denser and smaller. The results from this study will help us understand the details of the magnetization reversal process in the p-SAF. 展开更多
关键词 perpendicular synthetic antiferromagnet first-order reversal curves magnetization reversal pro-cess DOMAIN
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Quality influencing factors of dispersion curves from short period dense arrays based on a convolutional neural network across the north section of the Xiaojiang fault area
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作者 Si Chen Rui Gao +5 位作者 Zhanwu Lu Yao Liang Wei Cai Lifu Cao Zilong Chen Guangwen Wang 《Earthquake Science》 2023年第3期200-211,共12页
The number of dispersion curves increases significantly when the scale of a short-period dense array increases.Owing to a substantial increase in data volume,it is important to quickly evaluate dispersion curve qualit... The number of dispersion curves increases significantly when the scale of a short-period dense array increases.Owing to a substantial increase in data volume,it is important to quickly evaluate dispersion curve quality as well as select the available dispersion curve.Accordingly,this study quantitatively evaluated dispersion curve quality by training a convolutional neural network model for ambient noise tomography using a short-period dense array.The model can select high-quality dispersion curves that exhibit a≤10%difference between the results of manual screening and the proposed model.In addition,this study established a dispersion curve loss function by analyzing the quality of the dispersion curve and the corresponding influencing factors,thereby estimating the number of available dispersion curves for the existing observation systems.Furthermore,a Monte Carlo simulation experiment is used to illustrates the station-pair interval distance probability density function,which is independent of station number in the observational system with randomly deployed stations.The results suggested that the straight-line length should exceed 15 km to ensure that loss rate of dispersion curves remains<0.5,while maintaining the threshold ambient noise tomography accuracy within the study area. 展开更多
关键词 convolutional neural network ambient noise tomography dispersion curve
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