Brownian motion

布朗运动
  • 文章类型: Journal Article
    本研究使用勒让德光谱搭配方法(LSCM)对随机寨卡病毒以及最优控制模型进行了计算研究。通过所提出的随机微分方程将随机性积累到模型中,我们利用随机波动对疾病的进展和传播至关重要。的稳定性,认真分析了LSCM的收敛性和准确性,并证明了其在解决复杂流行病学模型方面的优势。此外,这项研究评估了各种控制策略,如治疗,预防和治疗农药控制,并确定干预成本的最佳组合,并将建议的感染率降至最低。给定模型的基本属性,如再现数,在有和没有控制策略的情况下确定。对于R0<0,该模型满足无病均衡,在这种情况下,疾病会在一段时间后消失,而对于R0>1,那么就满足了地方性均衡,在这种情况下,疾病在人群中以更高的规模传播。基本发现承认随机音素对控制策略的鲁棒性和有效性的重大影响,这些控制策略加速了对具有成本效益和多方面方法的需求。最后,这些结果为公共卫生部门提供了有价值的见解,可以在现实世界中更令人印象深刻地缓解寨卡病毒的爆发和管理。
    This study presents a computational investigation of a stochastic Zika virus along with optimal control model using the Legendre spectral collocation method (LSCM). By accumulation of stochasticity into the model through the proposed stochastic differential equations, we appropriating the random fluctuations essential in the progression and disease transmission. The stability, convergence and accuracy properties of the LSCM are conscientiously analyzed and also demonstrating its strength for solving the complex epidemiological models. Moreover, the study evaluates the various control strategies, such as treatment, prevention and treatment pesticide control, and identifies optimal combinations that the intervention costs and also minimize the proposed infection rates. The basic properties of the given model, such as the reproduction number, were determined with and without the presence of the control strategies. For R 0 < 0 , the model satisfies the disease-free equilibrium, in this case the disease die out after some time, while for R 0 > 1 , then endemic equilibrium is satisfied, in this case the disease spread in the population at higher scale. The fundamental findings acknowledge the significant impact of stochastic phonemes on the robustness and effectiveness of control strategies that accelerating the need for cost-effective and multi-faceted approaches. In last the results provide the valuable insights for public health department to enabling more impressive mitigation of Zika virus outbreaks and management in real-world scenarios.
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  • 文章类型: Journal Article
    掌握纳米粒子形态的自组织是软物质物理和薄膜生长的关键。二氧化硅(SiO2)纳米颗粒是软物质中纳米马达的典型模型。这里,重点是在极端条件下SiO2纳米颗粒的自组织行为。揭示了操纵金属衬底的状态深刻地决定了SiO2纳米粒子的运动特性。这种操作引发了复杂形态和独特模式的出现。采用反应扩散模型,证明了布朗运动和Marangoni驱动的运动在塑造分形结构和径向图灵图案中所起的基本作用,分别。值得注意的是,这些径向图灵图案展示了超均匀的顺序,具有挑战性的薄膜形态的传统观念。这些发现为制作非平衡形态材料铺平了道路,具有自我修复的潜力,适应性,创新应用。
    Mastering the self-organization of nanoparticle morphologies is pivotal in soft matter physics and film growth. Silicon dioxide (SiO2) nanoparticles are an archetypical model of nanomotor in soft matter. Here, the emphasis is on the self-organizing behavior of SiO2 nanoparticles under extreme conditions. It is unveiled that manipulating the states of the metal substrate profoundly dictates the motion characteristics of SiO2 nanoparticles. This manipulation triggers the emergence of intricate morphologies and distinctive patterns. Employing a reaction-diffusion model, the fundamental roles played by Brownian motion and Marangoni-driven motion in shaping fractal structures and radial Turing patterns are demonstrated, respectively. Notably, these radial Turing patterns showcase hyperuniform order, challenging conventional notions of film morphology. These discoveries pave the way for crafting non-equilibrium morphological materials, poised with the potential for self-healing, adaptability, and innovative applications.
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  • 文章类型: Journal Article
    刀具磨损预测在工业生产中具有重要意义。当前刀具磨损预测方法主要依靠机器学习的间接估计,更侧重于估计当前刀具磨损状态,缺乏对随机不确定性因素的有效量化。为了克服这些缺点,本文提出了一种预测刀具磨损的新方法。在离线阶段,使用布朗运动随机过程对多个退化特征进行建模,并训练SVR模型以映射特征和工具磨损值。在联机阶段,贝叶斯推理用于更新特征退化模型的随机参数,并使用模拟样本估计了特征的未来趋势。将估算结果输入到SVR模型中,以分布密度的形式实现对刀具磨损的提前预测。使用实验工具磨损数据集验证了该方法的有效性。结果表明,该方法在预测精度和稳定性方面具有优越性。
    Tool wear prediction is of great significance in industrial production. Current tool wear prediction methods mainly rely on the indirect estimation of machine learning, which focuses more on estimating the current tool wear state and lacks effective quantification of random uncertainty factors. To overcome these shortcomings, this paper proposes a novel method for predicting cutting tool wear. In the offline phase, the multiple degradation features were modeled using the Brownian motion stochastic process and a SVR model was trained for mapping the features and the tool wear values. In the online phase, the Bayesian inference was used to update the random parameters of the feature degradation model, and the future trend of the features was estimated using simulation samples. The estimation results were input into the SVR model to achieve in-advance prediction of the cutting tool wear in the form of distribution densities. An experimental tool wear dataset was used to verify the effectiveness of the proposed method. The results demonstrate that the method shows superiority in prediction accuracy and stability.
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  • 文章类型: Journal Article
    沙漠蚂蚁是一些最有趣的昆虫航海家,几十年来一直引起科学家的注意。这包括目标方法过程中的行走轨迹结构以及巢穴和熟悉的喂食点的搜索行为。在本研究中,我们分析了行走方向变化的轨迹。量化了蚂蚁的方向变化,即,计算给定弧长λ的轨迹增量之间的角度θ。这是针对不同的长度尺度λ完成的,根据我们分析沙漠蚂蚁路径相对于长度尺度的特征的目标。首先,通过两个以上的数量级改变λ,证明了搜索行为的随机游走分量的典型布朗运动特征。出乎意料的是,这种随机游走分量也存在于——据说相当线性的——接近轨迹中。第二,与随机游走特征的均匀角度分布有很小但明显的偏差。这对于特定的搜索情况是正确的,大多接近(虚拟)目标位置。第三,在喂食器位置的经验导致了更直的方法和更集中的搜索,巢穴搜索也是如此,虽然程度较小。一起来看,这些结果验证和扩展了先前关于沙漠蚂蚁路径特征的研究。特别感兴趣的是无处不在的布朗运动特征及其接近目标位置的特定偏差,表示意外的结构化搜索行为。
    Desert ants stand out as some of the most intriguing insect navigators, having captured the attention of scientists for decades. This includes the structure of walking trajectories during goal approach and search behaviour for the nest and familiar feeding sites. In the present study, we analysed such trajectories with regard to changes in walking direction. The directional change of the ants was quantified, i.e. an angle θ between trajectory increments of a given arclength λ was computed. This was done for different length scales λ, according to our goal of analysing desert ant path characteristics with respect to length scale. First, varying λ through more than two orders of magnitude demonstrated Brownian motion characteristics typical of the random walk component of search behaviour. Unexpectedly, this random walk component was also present in - supposedly rather linear - approach trajectories. Second, there were small but notable deviations from a uniform angle distribution that is characteristic of random walks. This was true for specific search situations, mostly close to the (virtual) goal position. And third, experience with a feeder position resulted in straighter approaches and more focused searches, which was also true for nest searches, albeit to a lesser extent. Taken together, these results both verify and extend previous studies on desert ant path characteristics. Of particular interest are the ubiquitous Brownian motion signatures and specific deviations thereof close to the goal position, indicative of unexpectedly structured search behaviour.
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  • 文章类型: Journal Article
    群机器人通常是探索恶劣环境和搜索和救援操作的首选。本研究探讨了影响自主机器人群运动策略的因素及其对野外群分布的影响,采用基于仿真的分析。 本研究由两部分组成:最初,机器人作为被动实体经历自由落体,其次是一个 阶段,他们采用预定义的移动策略从他们的下降位置。本研究旨在研究初始位置和相关参数如何影响运动特性和最终群体分布。为了实现这一目标,四个参数-半径,高度,质量,并确定了 恢复系数,每个都分配了三个不同的值。这项研究观察到 这些参数对机器人运动的影响,考虑随机行走等运动策略, LevyWalk,马尔可夫过程,和布朗运动。结果表明,增加的参数值 引起的位置值的变化的自由落体在第一部分,这是第二部分的初始位置,以不同的方式影响运动策略。关于机器人的径向和角度扩展,对结果进行了 分析。径向扩散测量群元素从其初始位置扩散的距离,而角度扩展表示机器人根据极角分布的均匀性。该研究全面调查了自主机器人群的运动策略如何受到参数的影响,以及这些效应如何在结果中体现。这些发现预计将提高 自主机器人群在探索任务中的有效利用。 关键词:SwarmRobotics,自主机器人,随机漫步,LevyWalk,布朗运动,马尔可夫 过程。
    Swarm robots are frequently preferred for the exploration of harsh environments and search and rescue operations. This study explores the factors that influence the movement strategies of autonomous robot swarms and their impact on swarm distribution in the field, employing simulation-based analysis. The research consists of two parts: initially, robots undergo free-fall as passive entities, followed by a phase where they employ predefined movement strategies from their fall positions. The study aims to investigate how the initial position and related parameters affect movement characteristics and the ultimate swarm distribution. To achieve this objective, four parameters-radius, height, mass, and the Coefficient of Restitution-were identified, each assigned three different values. The study observes the effects of these parameters on robot motion, considering motion strategies such as Random Walk, Levy Walk, Markov Process, and Brownian Motion. Results indicate that increasing parameter values induce changes in the position values of the free-falling swarm in the first part, which is the initial position for the second part, influencing movement strategies in diverse ways. The outcomes are analyzed concerning the radial and angular spread of the robots. Radial spread measures how far swarm elements spread from their initial positions, while angular spread indicates how homogeneously the robots are distributed according to the polar angle. The study comprehensively investigates how the movement strategies of autonomous robot swarms are impacted by parameters and how these effects manifest in the results. The findings are anticipated to enhance the effective utilization of autonomous robot swarms in exploration missions.
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  • 文章类型: Journal Article
    沙漠蚂蚁是一些最有趣的昆虫航海家,几十年来一直引起科学家的注意。这包括目标方法过程中的行走轨迹结构以及巢穴和熟悉的喂食点的搜索行为。在本研究中,我们分析了行走方向变化的轨迹。量化了蚂蚁的方向变化,即,计算给定弧长λ的轨迹增量之间的角度θ。这是针对不同的长度尺度λ完成的,根据我们分析沙漠蚂蚁路径相对于长度尺度的特征的目标。首先,通过两个以上的数量级改变λ,证明了搜索行为的随机游走分量的典型布朗运动特征。出乎意料的是,这种随机游走分量也存在于——据说相当线性的——接近轨迹中。第二,与随机游走特征的均匀角度分布有很小但明显的偏差。这对于特定的搜索情况是正确的,大多接近(虚拟)目标位置。第三,在喂食器位置的经验导致了更直的方法和更集中的搜索,巢穴搜索也是如此,虽然程度较小。一起来看,这些结果验证和扩展了先前关于沙漠蚂蚁路径特征的研究。特别感兴趣的是无处不在的布朗运动特征及其接近目标位置的特定偏差,表示意外的结构化搜索行为。
    Desert ants stand out as some of the most intriguing insect navigators, having captured the attention of scientists for decades. This includes the structure of walking trajectories during goal approach and search behaviour for the nest and familiar feeding sites. In the present study, we analysed such trajectories with regard to changes in walking direction. The directional change of the ants was quantified, i.e. an angle θ between trajectory increments of a given arclength λ was computed. This was done for different length scales λ, according to our goal of analysing desert ant path characteristics with respect to length scale. First, varying λ through more than two orders of magnitude demonstrated Brownian motion characteristics typical of the random walk component of search behaviour. Unexpectedly, this random walk component was also present in - supposedly rather linear - approach trajectories. Second, there were small but notable deviations from a uniform angle distribution that is characteristic of random walks. This was true for specific search situations, mostly close to the (virtual) goal position. And third, experience with a feeder position resulted in straighter approaches and more focused searches, which was also true for nest searches, albeit to a lesser extent. Taken together, these results both verify and extend previous studies on desert ant path characteristics. Of particular interest are the ubiquitous Brownian motion signatures and specific deviations thereof close to the goal position, indicative of unexpectedly structured search behaviour.
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  • 文章类型: Journal Article
    沙漠蚂蚁是一些最有趣的昆虫航海家,几十年来一直引起科学家的注意。这包括目标方法过程中的行走轨迹结构以及巢穴和熟悉的喂食点的搜索行为。我们根据步行方向的变化来分析这些轨迹。蚂蚁的方向变化被量化,即,计算给定弧长λ的轨迹增量之间的角度θ。这是针对不同的长度尺度λ完成的,根据我们分析沙漠蚂蚁路径相对于长度尺度的特征的目标。(i)将λ变化超过两个数量级,证明了搜索行为随机游走分量的典型布朗运动特征。出乎意料的是,这种随机游走分量也存在于——据说相当线性的——接近轨迹中。(ii)与随机游走特征的均匀角分布有很小但明显的偏差。这对于特定的搜索情况是正确的,大多接近(虚拟)目标位置。(iii)具有喂食器位置的经验导致更笔直的方法和更集中的搜索,巢穴搜索也是如此,尽管程度较小。一起来看,这些结果验证和扩展了先前关于沙漠蚂蚁路径特征的研究。特别感兴趣的是无处不在的布朗运动特征及其接近目标位置的特定偏差,表示意外的结构化搜索行为。
    Desert ants stand out as some of the most intriguing insect navigators, having captured the attention of scientists for decades. This includes the structure of walking trajectories during goal approach and search behaviour for the nest and familiar feeding sites. In the present study, we analysed such trajectories with regard to changes in walking direction. The directional change of the ants was quantified, i.e. an angle θ between trajectory increments of a given arclength λ was computed. This was done for different length scales λ, according to our goal of analysing desert ant path characteristics with respect to length scale. First, varying λ through more than two orders of magnitude demonstrated Brownian motion characteristics typical of the random walk component of search behaviour. Unexpectedly, this random walk component was also present in - supposedly rather linear - approach trajectories. Second, there were small but notable deviations from a uniform angle distribution that is characteristic of random walks. This was true for specific search situations, mostly close to the (virtual) goal position. And third, experience with a feeder position resulted in straighter approaches and more focused searches, which was also true for nest searches, albeit to a lesser extent. Taken together, these results both verify and extend previous studies on desert ant path characteristics. Of particular interest are the ubiquitous Brownian motion signatures and specific deviations thereof close to the goal position, indicative of unexpectedly structured search behaviour.
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  • 文章类型: Journal Article
    当写下与热浴接触的“系统”的时间演化的Langevin方程时,人们通常会隐含(通常是默许)假设热环境始终处于平衡状态。这里,我们以这个假设为起点,从热浴的角度来阐述与热浴接触的系统演变的问题,which,因为它处于平衡状态,可以用微规范集合来描述。我们证明了浴缸的微规范合奏,以及浴和系统的所有成分的哈密顿运动方程,产生了一个单独的系统演化的Langevin方程。摩擦系数是根据熔池颗粒与系统之间相互作用力的自相关函数给出的,爱因斯坦的关系恢复了。此外,建立了与福克-普朗克方程的联系。
    When writing down a Langevin equation for the time evolution of a \"system\" in contact with a thermal bath, one typically makes the implicit (and often tacit) assumption that the thermal environment is in equilibrium at all times. Here, we take this assumption as a starting point to formulate the problem of a system evolving in contact with a thermal bath from the perspective of the bath, which, since it is in equilibrium, can be described by the microcanonical ensemble. We show that the microcanonical ensemble of the bath, together with the Hamiltonian equations of motion for all the constituents of the bath and system together, give rise to a Langevin equation for the system evolution alone. The friction coefficient turns out to be given in terms of auto-correlation functions of the interaction forces between the bath particles and the system, and the Einstein relation is recovered. Moreover, the connection to the Fokker-Planck equation is established.
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  • 文章类型: Journal Article
    跟踪快速纳米孔易位分析物需要一个高频测量系统,该系统保证时间分辨率优于1µs。这种约束实际上可能会将挑战从增加采样带宽转移到处理频率通常高于10kHz的快速增长的噪声。可能使它仍然不确定是否明确捕获所有易位事件。这里,一个数值模拟模型是作为一个替代来辨别易位事件与不同的实验设置,包括孔隙尺寸,偏置电压,分析物的电荷状态,盐浓度,和电解质粘度。该模型允许同时分析沿着其个体轨迹施加在大分析物群组上的力;这些力负责分析物移动,最终导致纳米孔移位。通过追踪分析物的轨迹,发现布朗力主导电解质中的分析物运动,直到电渗力决定最终移位作用的最后时刻。模拟链霉亲和素的分析物的平均停留时间从≈6减少到≈1µs,偏置电压从±100增加到±500mV。模拟的易位事件在质量上与链霉亲和素的实验数据一致。仿真模型也有助于新型固态纳米孔传感器的设计。
    Tracing fast nanopore-translocating analytes requires a high-frequency measurement system that warrants a temporal resolution better than 1 µs. This constraint may practically shift the challenge from increasing the sampling bandwidth to dealing with the rapidly growing noise with frequencies typically above 10 kHz, potentially making it still uncertain if all translocation events are unambiguously captured. Here, a numerical simulation model is presented as an alternative to discern translocation events with different experimental settings including pore dimension, bias voltage, the charge state of the analyte, salt concentration, and electrolyte viscosity. The model allows for simultaneous analysis of forces exerting on a large analyte cohort along their individual trajectories; these forces are responsible for the analyte movement leading eventually to the nanopore translocation. Through tracing the analyte trajectories, the Brownian force is found to dominate the analyte movement in electrolytes until the last moment at which the electroosmotic force determines the final translocation act. The mean dwell time of analytes mimicking streptavidin decreases from ≈6 to ≈1 µs with increasing the bias voltage from ±100 to ±500 mV. The simulated translocation events qualitatively agree with the experimental data with streptavidin. The simulation model is also helpful for the design of new solid-state nanopore sensors.
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  • 文章类型: Journal Article
    我们记录并分析了有袋动物Didelphisaurita在不同时间尺度上的运动模式。通过使用线轴和线技术在每日尺度上收集动物的轨迹,在无线电跟踪装置的帮助下,动物的行进距离以数周为间隔进行估计。截断的Lévy飞行很好地描述了小规模的运动,而大规模运动会产生与布朗运动兼容的距离分布。这些动物的运动行为模型,基于在小规模数据上校准的截断的Lévy飞行,在1周左右的短时间间隔后,收敛到布朗行为。这些结果表明,无论是列维飞行还是布朗运动行为,将取决于动物路径的聚集规模。在这种特殊情况下,由于日常数据中存在的粗鲁截断的影响产生了对布朗行为的快速收敛,Lévy飞行对于描述这些动物的局部扩散特性变得很少有兴趣,结果很好地接近正常的扩散过程,而不是快速的扩散过程,异常的一个。有趣的是,我们能够描述两个运动阶段,作为聚合产生的统计效应的结果,无需引入生态约束或在不同时空尺度上运行的机制。这个结果是普遍感兴趣的,因为它可能是在不同分类单元和各种系统中以不同的时空尺度描述运动现象学的关键要素。
    We record and analyze the movement patterns of the marsupial Didelphis aurita at different temporal scales. Animals trajectories are collected at a daily scale by using spool-and-line techniques and, with the help of radio-tracking devices, animals traveled distances are estimated at intervals of weeks. Small-scale movements are well described by truncated Lévy flight, while large-scale movements produce a distribution of distances which is compatible with a Brownian motion. A model of the movement behavior of these animals, based on a truncated Lévy flight calibrated on the small scale data, converges towards a Brownian behavior after a short time interval of the order of 1 week. These results show that whether Lévy flight or Brownian motion behaviors apply, will depend on the scale of aggregation of the animals paths. In this specific case, as the effect of the rude truncation present in the daily data generates a fast convergence towards Brownian behaviors, Lévy flights become of scarce interest for describing the local dispersion properties of these animals, which result well approximated by a normal diffusion process and not a fast, anomalous one. Interestingly, we are able to describe two movement phases as the consequence of a statistical effect generated by aggregation, without the necessity of introducing ecological constraints or mechanisms operating at different spatio-temporal scales. This result is of general interest, as it can be a key element for describing movement phenomenology at distinct spatio-temporal scales across different taxa and in a variety of systems.
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