nonlinearity

非线性
  • 文章类型: Journal Article
    我们报道了在连续波激光下使用Z扫描技术研究的ZnO@C-N复合微球和纯ZnO的三阶非线性光学(NLO)特性。ZnO@C-N复合微球已在两种不同的前体浓度下水热合成,以具有不同杂质水平的结构。此外,在退火工艺下制备了纯ZnO。通过使用开孔Z扫描技术测量样品的非线性光吸收,并根据双光子吸收(TPA)机理进行评估。此外,ZnO@C-N和ZnO微结构均表现出负的非线性折射率(NLR),这与自散焦效应有关。(NLR)值的顺序,约为10-10(cm2/W),样品的NLA系数约为10-5(cm/W)。相对于增加的激光入射强度,NLA系数具有与NLR类似的行为。结果表明,ZnO@C-N复合材料的非线性响应高于纯ZnO,在较高的前驱体浓度下ZnO@C-N表现出与其他样品相比的最大量的NLA和NLR系数。这一观察归因于由于杂质的存在而引起的材料的光学和结构性质的变化,强调工程材料存在杂质,以改善非线性性能。
    We report the third-order nonlinear optical (NLO) properties of ZnO@C-N composite microspheres and pure ZnO which have been investigated with the Z-scan technique under continuous wave laser. ZnO@C-N composite microspheres have been hydrothermally synthesized at two different precursor concentrations to have structures at different impurity levels. Moreover, pure ZnO is prepared under the annealing process. The nonlinear optical absorption of samples was measured by using the open-aperture Z-scan technique and was evaluated relating to the two-photon absorption (TPA) mechanism. Moreover, both ZnO@C-N and ZnO microstructures exhibited a negative nonlinear refractive index (NLR) referring to the self-defocusing effect. The order of the (NLR) value, is about 10-10(cm2/W) and, the NLA coefficients of specimens are in the order of 10-5(cm/W). The NLA coefficient has a similar behavior as the NLR versus increasing incident intensity of the laser. The results show that the nonlinearity response of ZnO@C-N composites is higher than the pure ZnO and ZnO@C-N at higher precursor concentrations exhibits the maximum amount of NLA and NLR coefficients compared to other samples. This observation which is attributed to the change in optical and structural properties of material due to impurity presence, underscores the presence of impurity for engineering materials to improve the nonlinearity properties.
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  • 文章类型: Journal Article
    目的:探讨如何使用变化点方法分析复杂的纵向数据,并检测康复过程中何时发生有意义的变化(变化点)。
    方法:本设计是一项前瞻性的单病例观察性研究,研究对象是一名职业俱乐部的足球运动员,该运动员在高速跑步训练中出现急性下肢肌肉损伤。康复计划是在俱乐部医疗团队的监督下在足球俱乐部完成的。在受伤之前收集了四个健康指标和5个跑步表现指标,直到球员恢复比赛为止。
    结果:收集了超过130天的数据。在单变量分析中,压力的变化点,睡眠,心情,和酸痛分别位于第30、47、50和50天。总距离的变化点,加速度,最大速度,减速,和高速运行分别位于第32、34、37、41和41天。多变量分析导致健康指标和运行绩效指标的单个变化点,分别在第50天和第67天。
    结论:单变量方法提供了有关变化点的序列和时间点的信息。多变量方法为多个指标提供了一个共同的变化点,这些信息将使临床医生对康复过程中的变化有一个广泛的概述。临床医生可能会考虑使用变化点方法来整合和可视化来自多个来源的数据,以评估运动员沿重返运动连续体的进展。
    OBJECTIVE: To explore how the change-point method can be used to analyze complex longitudinal data and detect when meaningful changes (change points) have occurred during rehabilitation.
    METHODS: This design is a prospective single-case observational study of a football player in a professional club who sustained an acute lower-limb muscle injury during high-speed running in training. The rehabilitation program was entirely completed in the football club under the supervision of the club\'s medical team. Four wellness metrics and 5 running-performance metrics were collected before the injury and until the player returned to play.
    RESULTS: Data were collected over 130 days. In the univariate analysis, the change points for stress, sleep, mood, and soreness were located on days 30, 47, 50, and 50, respectively. The change points for total distance, acceleration, maximum speed, deceleration, and high-speed running were located on days 32, 34, 37, 41, and 41, respectively. The multivariate analysis resulted in a single change point for the wellness metrics and running-performance metrics, on days 50 and 67, respectively.
    CONCLUSIONS: The univariate approach provided information regarding the sequence and time point of the change points. The multivariate approach provided a common change point for multiple metrics, information that would benefit clinicians to have a broad overview of the changes in the rehabilitation process. Clinicians may consider the change-point method to integrate and visualize data from multiple sources to evaluate athletes\' progression along the return-to-sport continuum.
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  • 文章类型: Journal Article
    电渗技术一直被认为是一种有前途的技术,可以增强废污泥的脱水,低渗透土壤的稳定和环境修复。然而,电渗渗透系数(keo)通常取恒定值,在可变电荷土壤中尤其不是这种情况。因此,无法解释电渗流(EOF)的非线性和方向相反。在这里,在自然可变电荷土壤的电渗实验中监测了电化学参数。观察到演化显示出明显的非线性行为并且是相关的。作者提出的综合Zeta电位模型用于模拟pH和电解质浓度变化引起的非线性keo。测试和模拟流量变化与超孔隙水压力分布之间的一致性证明了该理论的可靠性。通过耦合非线性keo和电压梯度Ex的模拟误差率从具有恒定参数的381.9%计算降低到29.4%。创新性地解释了EOF的反向方向。因此,数值模型将作为一个有用的工具来连接这些电化学参数,并为评估常用pH调节测量的贡献提供指导。
    Electro-osmosis has been valued as a promising technology to enhance the dewatering of waste sludge, stabilization and environmental remediation of soils with low permeability. However, the coefficient of electro-osmotic permeability (keo) is commonly taken as constant value which is particularly not the case in variable charge soil. As a result, the nonlinearity of the electro-osmotic flow (EOF) and the direction reverse could not be interpreted. Herein, the electro-chemical parameters were monitored in electro-osmotic experiment with natural variable charge soil. It was observed that the evolutions showed significant nonlinear behavior and were correlated. The comprehensive Zeta potential model proposed by the authors was applied to simulate the nonlinear keo induced by the variable pH and electrolyte concentration. The agreement between tested and simulated flow rate variation and excess pore water pressure distribution demonstrated the reliability of the theory. The error rate of the simulations through coupling nonlinear keo and voltage gradient Ex was reduced to 29.4% from 381.9% of calculations with constant parameters. The direction reverse of EOF was innovatively interpreted. Hence, the numerical model would act as a useful tool to connect these electro-chemical parameters and provide guidance to evaluate contributions of commonly used pH conditioning measurements.
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  • 文章类型: Journal Article
    在过去的十年里,恒温动力学理论已被提出作为对活性物质的复杂系统进行建模的一般范例,特别是,在生物学中。恒温动力学理论的均质和不均匀框架已用于建模现象,这些现象是元素之间相互作用的结果。称为活性粒子,组成系统。功能子系统包含能够执行相同任务的异质活性粒子,称为活动。活性物质生命系统通常不平衡地运行;因此,引入了数学恒温器,以调节粒子活动的波动。通过引入代表活动过渡的保守和非保守相互作用来获得功能子系统的时间演化,自然出生/死亡,诱导增殖/破坏,和活性粒子的突变。这篇综述论文分为两部分:在第一部分中,综述涉及可以在过去十年的文献中找到的恒温动力学理论的数学框架,并提出了统一的方法;评论的第二部分致力于在过去十年中针对复杂的生物系统提出的恒温动力学理论中得出的特定数学模型,如伤口愈合疾病,人类免疫系统的识别过程和学习动态,在癌症-免疫系统竞争过程中发生的隐藏学习动力学和免疫编辑过程。从理论和应用的角度探讨了未来的研究视角,这表明应用科学的不同学者之间的重要相互作用,以及多学科方法或更确切地说是对每个活性物质系统进行建模的理论的愿望。
    In the last decade, the thermostatted kinetic theory has been proposed as a general paradigm for the modeling of complex systems of the active matter and, in particular, in biology. Homogeneous and inhomogeneous frameworks of the thermostatted kinetic theory have been employed for modeling phenomena that are the result of interactions among the elements, called active particles, composing the system. Functional subsystems contain heterogeneous active particles that are able to perform the same task, called activity. Active matter living systems usually operate out-of-equilibrium; accordingly, a mathematical thermostat is introduced in order to regulate the fluctuations of the activity of particles. The time evolution of the functional subsystems is obtained by introducing the conservative and the nonconservative interactions which represent activity-transition, natural birth/death, induced proliferation/destruction, and mutation of the active particles. This review paper is divided in two parts: In the first part the review deals with the mathematical frameworks of the thermostatted kinetic theory that can be found in the literature of the last decade and a unified approach is proposed; the second part of the review is devoted to the specific mathematical models derived within the thermostatted kinetic theory presented in the last decade for complex biological systems, such as wound healing diseases, the recognition process and the learning dynamics of the human immune system, the hiding-learning dynamics and the immunoediting process occurring during the cancer-immune system competition. Future research perspectives are discussed from the theoretical and application viewpoints, which suggest the important interplay among the different scholars of the applied sciences and the desire of a multidisciplinary approach or rather a theory for the modeling of every active matter system.
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  • 文章类型: Journal Article
    探讨职业足球运动员的身体和技术表现的动态以及各年龄段的变化。比赛统计数据是从中国超级联赛十个赛季(2012-2021年)的1900场比赛中收集的。广义加法模型在包括技术和物理变量在内的12个关键绩效指标中可视化了与年龄相关的趋势。揭示了以快速早期下降为特征的非线性轨迹,稳定的高峰期和加速的后期减少。身体指标从20年代初开始逐渐下降,然后短暂稳定,然后在30年代后进一步下降。相反,技术指标逐渐改善到20年代末和30年代初,然后再次下降。这项研究提供了新的证据,表明足球表现随着年龄的增长而非线性变化。有针对性的培训和发展战略应针对不同职业阶段的具体需求。
    To explore the dynamics in physical and technical performance of professional football players and changes across age groups. Match statistics were collected from 1900 games across ten seasons (2012-2021) in the Chinese Super League. Generalized additive models visualized age-related trends in 12 key performance indicators including technical and physical variables. Revealed nonlinear trajectories characterized by rapid early declines, stable peak periods and accelerated late decreases. Physical indicators decreased progressively from the early 20 s before stabilizing briefly then declining further after 30. Conversely, technical metrics gradually improved into the late 20 s and early 30 s prior to decreasing again. This study provides novel evidence that football performance changes nonlinearly across age. Targeted training and development strategies should be tailored to the specific needs of different career stages.
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  • 文章类型: Journal Article
    在本文中,基于离散悬链线理论,研究了弹性索结构在机械载荷作用下的非线性力学响应。在我们的数值方法中,电缆网被离散为多个节点和边缘,然后是弹性能量和相关的Hessian矩阵的解析公式,以实现动态模拟。基于离散微分几何(DDG)理论,提出了一种全隐式框架。通过向系统中添加阻尼力来得出目标对象的平衡配置,称为动态松弛法。研究了单个悬挂电缆的机械响应,并将其与分析解决方案进行了比较,以进行交叉验证。进一步详细讨论了一个更复杂的场景,由多根细长电缆组成的结构通过接头连接。利用我们离散数值框架的鲁棒性和效率,进行了系统参数扫描,以量化网络与不同数量的电缆和不同方向的纤维的力位移关系。最后,根据弹性索网的几何特性,提供了经验比例定律来解释弹性索网的刚度,材料特性,组件编号,和电缆方向。我们的结果将为揭示柔性结构和张力结构之间的联系提供新的见解,并可以激发机械和土木工程设备的创新设计。
    In this paper, the nonlinear mechanical response of elastic cable structures under mechanical load is studied based on the discrete catenary theory. A cable net is discretized into multiple nodes and edges in our numerical approach, which is followed by an analytical formulation of the elastic energy and the associated Hessian matrix to realize the dynamic simulation. A fully implicit framework is proposed based on the discrete differential geometry (DDG) theory. The equilibrium configuration of a target object is derived by adding damping force into the system, known as the dynamic relaxation method. The mechanical response of a single suspended cable is investigated and compared with the analytical solution for cross-validation. A more intricate scenario is further discussed in detail, where a structure consisting of multiple slender cables is connected through joints. Utilizing the robustness and efficiency of our discrete numerical framework, a systematic parameter sweep is performed to quantify the force displacement relationships of nets with the different number of cables and different directions of fibers. Finally, an empirical scaling law is provided to account for the rigidity of elastic cable net in terms of its geometric properties, material characteristics, component numbers, and cable orientations. Our results would provide new insight in revealing the connections between flexible structures and tensegrity structures, and could motivate innovative designs in both mechanical and civil engineered equipment.
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  • 文章类型: Journal Article
    先前的研究只是将低密度脂蛋白(LDL)与糖尿病性黄斑水肿(DME)概率之间的关系线性化,忽略了它们之间存在非线性关系的可能性。我们旨在研究2型糖尿病(T2DM)患者LDL与DME概率之间的非线性关系。
    本研究招募了2017年12月至2018年11月在广东省人民医院就诊的431名T2DM患者。采用多因素logistic回归模型评价LDL与DME概率的相关性。通过广义加性模型识别非线性关系。进行亚组分析以评估不同亚组中关联的一致性。
    LDL与DME概率呈正相关(OR=1.60,95%CI:1.10~2.34,P=0.0145)。发现了LDL和DME概率之间的非线性关系,LDL拐点在4.85mmol/L左右(95%CI:4.18~4.93,P=0.037)。拐点左右两侧的效应大小和置信区间分别为2.17(1.31至3.58)和0.26(0.04至1.77),分别。亚组分析显示其他变量对它们之间的关联没有影响。
    我们的发现提示在T2DM患者中LDL与DME概率呈正相关。LDL与DME概率之间呈非线性关系。我们的发现需要进一步的因果研究来证实。
    UNASSIGNED: Previous studies simply linearized the relationship between low density lipoprotein (LDL) and diabetic macular edema\'s (DME) probability, ignoring the possibility of a nonlinear relationship between them. We aimed to investigate the nonlinear relationship between LDL and DME probability in patients with type 2 diabetes mellitus (T2DM).
    UNASSIGNED: The study recruited 431 T2DM patients who attended Guangdong Provincial People\'s Hospital from December 2017 to November 2018. A multivariate logistic regression model was conducted to evaluate the association between LDL and DME probability. The nonlinear relationship was identified by generalized additive model. Subgroup analyses were performed to assess the consistency of the association in different subgroups.
    UNASSIGNED: LDL was positively associated with DME probability (OR=1.60, 95% CI: 1.10~2.34, P=0.0145) after adjusting for covariates. A nonlinear relationship between LDL and DME probability was discovered, with an inflection point for LDL around 4.85 mmol/L (95% CI: 4.18~4.93, P=0.037). The effect sizes and the confidence intervals on the left and right sides of inflection point were 2.17 (1.31 to 3.58) and 0.26 (0.04 to 1.77), respectively. Subgroup analyses revealed other variables had no effect on the association between them.
    UNASSIGNED: Our finding suggested LDL was positively correlated with DME probability in T2DM patients. And the relationship between LDL and DME probability was nonlinear. Our findings need to be confirmed by further causal researches.
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  • 文章类型: Journal Article
    气泡声学是相当发达的领域,主要是由于多个空化相关的超声波在液体中的应用。新应用,这需要详细研究超声波在固体材料中与气泡的接触,最近已经变得明显,并且关注基于分层技术的先进固体材料中孔隙率的可检测性,如复合材料和增材制造结构。为了阐明从液体到固体的转变,本文从两者之间的理论相似性开始,并进行了环氧树脂中气泡共振声学效应的实验研究。LDR频率显示为与气泡半径倒数,因此如果频率已知,则可以评估气泡半径。在LDR频率下激发的气泡及其次谐波(超谐波共振)表现出非常宽的高次谐波谱,这意味着用于对复合材料和其他材料中的孔隙率进行无损检测的非线性手段。
    Acoustics of bubbles is quite developed field mainly due to multiple cavitation-related ultrasonic applications in liquids. New applications, which require detailed studies of ultrasound encounter with bubble in solid materials, have become apparent recently and are concerned with detectability of porosity in advanced solid materials based on layered technology, like composite and additive manufactured structures. To elucidate the transition from liquids to solids the present paper starts from theoretical similarity between both and proceeds to experimental study of the resonance acoustic effects of air bubbles in epoxy resin. The LDR frequencies are shown to be reciprocal to the bubble radius so that the latter can be evaluated if the frequency is known. The bubbles excited at the LDR frequencies and their subharmonics (superharmonic resonance) manifest extraordinary wide higher harmonic spectra that implies a nonlinear means for nondestructive testing of porosity in composites and other materials.
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  • 文章类型: Journal Article
    2D半导体与光子晶体平板的集成提供了一种有吸引力的方法,可以在芯片兼容的几何结构中实现强光-物质耦合和激子-极化子形成。然而,为了开发实用的设备,至关重要的是,极化子激发易于调谐并表现出强非线性响应。在这里,我们研究了具有嵌入式单层半导体MoSe2的静电门控光子晶体板中的中性和带电激子-极化子,并通过实验证明了一种基于极化子非线性的光学控制新方法。我们表明,光子晶体晶胞内的介电环境的空间调制导致形成两种不同的激子物质,在光泵浦下,相应的带电激子-极化子的非线性响应显着不同。这种行为使得能够利用超短激光脉冲进行光学切换,并且可以通过静电栅极电压进行灵敏控制。我们的结果为在紧凑的芯片兼容实现中开发有源极化器件开辟了新的途径。
    Integration of 2D semiconductors with photonic crystal slabs provides an attractive approach to achieving strong light-matter coupling and exciton-polariton formation in a chip-compatible geometry. However, for the development of practical devices, it is crucial that polariton excitations are easily tunable and exhibit a strong nonlinear response. Here we study neutral and charged exciton-polaritons in an electrostatically gated photonic crystal slab with an embedded monolayer semiconductor MoSe2 and experimentally demonstrate a novel approach to optical control based on polariton nonlinearity. We show that spatial modulation of the dielectric environment within the photonic crystal unit cell results in the formation of two distinct excitonic species with significantly different nonlinear responses of the corresponding charged exciton-polaritons under optical pumping. This behavior enables optical switching with ultrashort laser pulses and can be sensitively controlled via an electrostatic gate voltage. Our results open new avenues toward the development of active polaritonic devices in a compact chip-compatible implementation.
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  • 文章类型: Journal Article
    通过促进经济多样化,解决对自然资源的依赖是实现可持续发展目标的组成部分,环境可持续性,和气候复原力。本研究采用2005-2019年“一带一路”国家平衡面板数据集,探讨自然资源依赖对绿色发展的影响。值得注意的是,我们分析的新颖性在于使用基于工具的技术进行实证分析,巩固了“一带一路”国家的“绿色发展诅咒假说”。机理分析表明,自然资源依赖通过削弱创新能力来抑制绿色发展,令人不安的制度质量,降低人口密度,挤出人力资本。Further,处理内生性的动态面板阈值模型验证了自然资源依赖与绿色发展之间的非线性关系。有趣的是,数字贸易比传统贸易提供更大的“弹性”,纠正资源诅咒困境。最后,异质性分析表明,绿色发展诅咒假说只存在于环境规制水平较高的国家和资源型国家。
    Addressing natural resource dependence is integral to achieving the Sustainable Development Goals by promoting economic diversification, environmental sustainability, and climate resilience. This study explores the effect of natural resource dependence on green development by adopting the balanced panel dataset from the \"Belt and Road\" countries from 2005 to 2019. Notably, the novelty of our analysis lies in the empirical analysis using instrument-based techniques that consolidate the \"green development curse hypothesis\" in the Belt and Road countries. The mechanism analysis reveals that natural resource dependence curbs green development by weakening innovative capability, disturbing institutional quality, reducing population density, and crowding out human capital. Further, the dynamic panel threshold model handling endogeneity verifies the nonlinear relationship between natural resource dependence and green development. Interestingly, digital trade offers greater \"resilience\" than traditional trade, correcting the resource curse dilemma. Finally, heterogeneity analyses indicate that the green development curse hypothesis only exists in countries with high-level environmental regulations and resource-based countries.
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