Dynamic modelling

  • 文章类型: Journal Article
    无磁体开关磁阻电机(SRM)速度-转矩特性非常适合牵引电机驱动特性及其优势,可最大限度地降低道路电动汽车的总成本。主要缺点是转矩和磁通脉动,在低速运行中产生了很高的性能。然而,新兴的直接转矩控制(DTC)操作的幅度通量和具有电压矢量(VV)的转矩估计由于有效开关状态和扇区分区精度的选择而给出了高转矩脉动。另一方面,现有的模型预测控制(MPC)具有多个目标和优化加权因子,由于系统动力学和约束而产生高转矩波动。因此,现有的DTC和MPC会导致高扭矩波动。本文提出了一个有限集(FS)-MPC,具有单个成本函数目标,没有加权因子:预测扭矩被认为是评估VV以进一步最小化波动。所选择的最佳VV使SRM驱动转矩和磁通波动在稳态和动态状态行为中最小化。开发了经典的DTC和提出的模型,并利用MATLAB/Simulink对仿真结果进行了验证。在SRM中运行的所提出的模型驱动实验结果,以证明与现有DTC相比,转矩和磁通波动的有效最小化。
    The magnet-less switched reluctance motor (SRM) speed-torque characteristics are ideally suited for traction motor drive characteristics and its advantage to minimize the overall cost of on-road EVs. The main drawbacks are torque and flux ripple, which have produced high in low-speed operation. However, the emerging direct torque control (DTC) operated magnitude flux and torque estimation with voltage vectors (VVs) gives high torque ripples due to the selection of effective switching states and sector partition accuracy. On the other hand, the existing model predictive control (MPC) with multiple objective and optimization weighting factors produces high torque ripples due to the system dynamics and constraints. Therefore, existing DTC and MPC can result in high torque ripples. This paper proposed a finite set (FS)-MPC with a single cost function objective without weighting factor: the predicted torque considered to evaluate VVs to minimize the ripples further. The selected optimal VV minimizes the SRM drive torque and flux ripples in steady and dynamic state behaviour. The classical DTC and proposed model were developed, and simulation results were verified using MATLAB/Simulink. The proposed model operated in SRM drives experimental results to prove the effective minimization of torque and flux ripples compared to the existing DTC.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    提出了描述注塑机动力学和注射过程的一维模型。该模型描述了由双泵电液变速驱动和灌装驱动的注射缸,使用无定形聚合物的注射成型过程的保持和冷却阶段。该模型被建议作为基于模型的压力控制器设计的基础,例如,喷嘴压力。重点是使用材料,构建模型的模具和机器属性,使得在制造硬件或进行实验之前分析和设计动态系统成为可能。提出的模型和开发的控制器与实验结果均显示出良好的一致性。所提出的方法本质上是通用的,可以使设计,机器的分析和评估,仅根据系统的物理特性进行控制器设计的材料和模具动力学。
    A 1D model describing the dynamics of an injection moulding machine and the injection process is presented. The model describes an injection cylinder actuated by a dual-pump electro-hydraulic speed-variable drive and the filling, holding and cooling phases of the injection moulding process utilising amorphous polymers. The model is suggested as the foundation for the design of model-based pressure controllers of, e.g., the nozzle pressure. The focus is on using material, mould and machine properties to construct the model, making it possible to analyse and design the dynamic system prior to manufacturing hardware or conducting experiments. Both the presented model and the developed controller show good agreement with experimental results. The proposed method is general in nature and enables the design, analysis and evaluation of the machine, material and mould dynamics for controller design based solely on the physical properties of the system.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    这篇综述强调了为基于生物和高级氧化工艺(AOP)的废水处理系统制定控制策略的重要性。目的是确保废水质量与环境法规保持一致,同时将运营成本降至最低。它强调了理解过程的动态行为在开发有效控制方案中的重要性。解释并列出了污水处理厂(WWTP)中最常见的过程控制策略。强调应根据过程动态行为和控制目标选择适当的控制方案。本研究进一步讨论了与废水处理过程控制相关的挑战,包括开发模型的不足,大多数控制策略对仿真阶段的局限性,对实时数据的迫切需求,以及与实施高级控制器硬件相关的财务和技术复杂性。讨论了实时数据的可用性实现可靠控制的必要性,在过程的合适位置或通过开发和实施软传感器来实现精确的硬件传感器。本研究建议对可用的执行器进行进一步调查,并选择最合适的执行器以在污水处理厂中实现稳健可靠的控制,特别是对于生物和基于AOP的治疗方法。
    This review emphasizes the significance of formulating control strategies for biological and advanced oxidation process (AOP)-based wastewater treatment systems. The aim is to guarantee that the effluent quality continuously aligns with environmental regulations while operating costs are minimized. It highlights the significance of understanding the dynamic behaviour of the process in developing effective control schemes. The most common process control strategies in wastewater treatment plants (WWTPs) are explained and listed. It is emphasized that the proper control scheme should be selected based on the process dynamic behaviour and control goal. This study further discusses the challenges associated with the control of wastewater treatment processes, including inadequacies in developed models, the limitations of most control strategies to the simulation stage, the imperative requirement for real-time data, and the financial and technical intricacies associated with implementing advanced controller hardware. It is discussed that the necessity of the availability of real-time data to achieve reliable control can be achieved by implementing proper, accurate hardware sensors in suitable locations of the process or by developing and implementing soft sensors. This study recommends further investigation on available actuators and the criteria for choosing the most appropriate one to achieve robust and reliable control in WWTPs, especially for biological and AOP-based treatment approaches.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    生物群落是在共同位置相互作用的各种物种的种群。微生物群落,它们是由微生物形成的,在自然界中无处不在,并越来越多地用于生物技术和生物医学应用。它们是非线性系统,其动力学可以通过常微分方程(ODE)模型准确描述。已经提出了许多ODE模型来描述微生物群落。然而,它们中大多数的结构可识别性和可观察性-也就是说,通过观察其输出来推断其参数和内部状态的理论可能性尚未确定。重要的是要确定一个模型是否具有这些属性,因为,在他们缺席的情况下,模型做出可靠预测的能力可能会受到损害。因此,在本文中,我们分析了微生物群落模型的主要家族的这些属性。我们考虑几个维度和测量;总的来说,我们分析了一百多种不同的配置。我们发现其中一些是完全可识别和可观察的,但是在典型的实验条件下,许多病例在结构上无法识别和/或无法观察到。我们的结果有助于确定哪些建模框架可以用于这一新兴领域的给定目的,哪些应该避免。
    Biological communities are populations of various species interacting in a common location. Microbial communities, which are formed by microorganisms, are ubiquitous in nature and are increasingly used in biotechnological and biomedical applications. They are nonlinear systems whose dynamics can be accurately described by models of ordinary differential equations (ODEs). A number of ODE models have been proposed to describe microbial communities. However, the structural identifiability and observability of most of them-that is, the theoretical possibility of inferring their parameters and internal states by observing their output-have not been determined yet. It is important to establish whether a model possesses these properties, because, in their absence, the ability of a model to make reliable predictions may be compromised. Hence, in this paper, we analyse these properties for the main families of microbial community models. We consider several dimensions and measurements; overall, we analyse more than a hundred different configurations. We find that some of them are fully identifiable and observable, but a number of cases are structurally unidentifiable and/or unobservable under typical experimental conditions. Our results help in deciding which modelling frameworks may be used for a given purpose in this emerging area, and which ones should be avoided.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    我们解决了从回顾性研究中推断的一个问题,其中变量的值是在调查之日测量的,但用作调查之前很久发生的事件的协变量。这引起问题,因为当前日期(预期)协变量的值不遵循事件的时间顺序。我们提出了一种动态贝叶斯方法来共同建模预期协变量和感兴趣的事件,并允许预期协变量的影响随时间变化。通过调查时间对瑞典男性离婚风险的教育影响的数据来说明这些问题。总体结果表明,未能适应教育的预期性质会导致不同教育水平的离婚相对风险升高。结果部分地与基于相同数据集的分析的先前发现一致。更重要的是,我们的发现提供了新的见解,即预期协变量导致的偏倚随婚姻持续时间而变化.
    We address a problem in inference from retrospective studies where the value of a variable is measured at the date of the survey but is used as covariate to events that have occurred long before the survey. This causes problem because the value of the current-date (anticipatory) covariate does not follow the temporal order of events. We propose a dynamic Bayesian approach for modelling jointly the anticipatory covariate and the event of interest, and allowing the effects of the anticipatory covariate to vary over time. The issues are illustrated with data on the effects of education attained by the survey-time on divorce risks among Swedish men. The overall results show that failure to adjust for the anticipatory nature of education leads to elevated relative risks of divorce across educational levels. The results are partially in accordance with previous findings based on analyses of the same data set. More importantly, our findings provide new insights in that the bias due to anticipatory covariates varies over marriage duration.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

       PDF(Pubmed)

  • 文章类型: Journal Article
    目前关注的是模拟不同废水处理过程中微污染物的命运。此外,在过去的几年里,人们对开发包含悬浮生物质和生物膜的混合反应器越来越感兴趣。这里,一种新的模型,试图确定混合反应器中的微污染物的命运,如移动床生物膜反应器(MBBR),并称为ASM-生物膜-MPs模型考虑了导致微污染物去除的主要机制(吸附/解吸,生物降解,混合反应堆中的代谢)。该动态模型使用一级动力学用于生物转化和吸附/解吸方程,描述了混合反应器中微污染物的命运。此外,它考虑了碳氧化的反应,硝化,在好氧条件下附着和悬浮生物质中的反硝化作用。数学模型由三个相连的模型组成,用于模拟微污染物,悬浮生物质,和生物膜。根据活性污泥模型编号评估生化转化率。1(ASM1)的附着和悬浮生物质。该模型适用于实验室MBBR,添加含有4-壬基酚(4-NP)作为微污染物的合成废水,并准确地描述了COD的实验浓度,附着和悬浮的生物质,氮,和在不同负荷下工作180天期间获得的4-NP微污染物。sCOD在所有运行期间的模拟和实验之间的差异,NH4-N,NO3-N,附着和悬浮生物量浓度低于15%,10%,10%,5%和5%,分别。最后,计算了吸附和生物降解机制在4-NP命运中的贡献,当4-NP浓度设置为1µg/L时(生物降解=86.5%,吸附=5%)和50µg/L(生物降解=55.9%,吸附量=34.7%)。
    Modelling the fate of micropollutants in different wastewater treatment processes is of present concern. Moreover, during the last few years, there has been an increasing interest in the development of hybrid reactors which contain both suspended biomass and biofilm. Here, a new model developed which tries to determine the fate of micropollutants in hybrid reactors such as moving bed biofilm reactor (MBBR) and called the ASM-biofilm-MPs model considered the main mechanisms leading to the micropollutant removal (sorption/desorption, biodegradation, cometabolism) in hybrid reactors. This dynamic model describes the fate of micropollutants in a hybrid reactor using first-order kinetics for biotransformation and sorption/desorption equations. Also, it considered the reactions for carbon oxidation, nitrification, and denitrification in attached and suspended biomass under aerobic conditions. The mathematical model consists of three connected models for the simulation of micropollutants, suspended biomass, and biofilm. Biochemical conversions are evaluated according to the Activated Sludge Model No. 1 (ASM1) for both attached and suspended biomass. The model is applied for a laboratory MBBR, which fed with synthetic wastewater containing 4-nonylphenol (4-NP) as micropollutant, and accurately describes the experimental concentrations of COD, attached and suspended biomass, nitrogen, and 4-NP micropollutant obtained during 180 days working at different loadings. The differences between simulations and experiments in all operational periods for sCOD, NH4-N, NO3-N, and attached and suspended biomass concentrations were less than 15%, 10%, 10%, 5% and 5%, respectively. Finally, the contribution of adsorption and biodegradation mechanisms in the fate of 4-NP was calculated, when 4-NP concentration is set to 1 µg/L (biodegradation = 86.5%, sorption = 5%) and 50 µg/L (biodegradation = 55.9%, sorption = 34.7%).
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    Weaning is a critical transition phase in swine production in which piglets must cope with different stressors that may affect their health. During this period, the prophylactic use of antibiotics is still frequent to limit piglet morbidity, which raises both economic and public health concerns such as the appearance of antimicrobial-resistant microbes. With the interest of developing tools for assisting health and management decisions around weaning, it is key to provide robustness indexes that inform on the animals\' capacity to endure the challenges associated with weaning. This work aimed at developing a modelling approach for facilitating the quantification of piglet resilience to weaning. A total of 325 Large White pigs weaned at 28 days of age were monitored and further housed and fed conventionally during the post-weaning period without antibiotic administration. Body weight and diarrhoea scores were recorded before and after weaning, and blood was sampled at weaning and 1 week later for collecting haematological data. A dynamic model was constructed based on the Gompertz-Makeham law to describe live weight trajectories during the first 75 days after weaning, following the rationale that the animal response is partitioned in two time windows (a perturbation and a recovery window). Model calibration was performed for each animal. Our results show that the transition time between the two time windows, as well as the weight trajectories are characteristic for each individual. The model captured the weight dynamics of animals at different degrees of perturbation, with an average coefficient of determination of 0.99, and a concordance correlation coefficient of 0.99. The utility of the model is that it provides biologically meaningful parameters that inform on the amplitude and length of perturbation, and the rate of animal recovery. Our rationale is that the dynamics of weight inform on the capability of the animal to cope with the weaning disturbance. Indeed, there were significant correlations between model parameters and individual diarrhoea scores and haematological traits. Overall, the parameters of our model can be useful for constructing weaning robustness indexes by using exclusively the growth curves. We foresee that this modelling approach will provide a step forward in the quantitative characterisation of robustness.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

  • 文章类型: Journal Article
    如今,常微分方程模型已广泛用于描述生物过程及其时间演化的机理。这些模型通常有许多未知和不可测量的参数,必须通过将模型拟合到实验数据来确定。为了执行此任务,称为参数估计或模型校准,建模者面临着参数可识别性差等挑战,缺乏足够信息的实验数据,并且在目标函数景观中存在局部极小值。随着模型尺寸的增大,这些问题往往会恶化,增加了计算复杂度和未知参数的数量。错误校准的模型是有问题的,因为它可能导致不准确的预测和误导性结论。对于非专家用户,有许多潜在的陷阱。这里,我们提供了一个协议,指导用户完成动态模型校准中涉及的所有步骤。我们用两个模型说明了该方法,并提供了重现结果并对新模型执行相同分析所需的所有代码。我们的协议为生物建模的从业者和研究人员提供了一站式指南,该指南同时紧凑且足够全面,可以涵盖问题的各个方面。
    Ordinary differential equation models are nowadays widely used for the mechanistic description of biological processes and their temporal evolution. These models typically have many unknown and nonmeasurable parameters, which have to be determined by fitting the model to experimental data. In order to perform this task, known as parameter estimation or model calibration, the modeller faces challenges such as poor parameter identifiability, lack of sufficiently informative experimental data and the existence of local minima in the objective function landscape. These issues tend to worsen with larger model sizes, increasing the computational complexity and the number of unknown parameters. An incorrectly calibrated model is problematic because it may result in inaccurate predictions and misleading conclusions. For nonexpert users, there are a large number of potential pitfalls. Here, we provide a protocol that guides the user through all the steps involved in the calibration of dynamic models. We illustrate the methodology with two models and provide all the code required to reproduce the results and perform the same analysis on new models. Our protocol provides practitioners and researchers in biological modelling with a one-stop guide that is at the same time compact and sufficiently comprehensive to cover all aspects of the problem.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    与设计中持续努力减少碳排放相比,建筑,和建设项目的运营阶段,对寿命结束阶段减排潜力的关注较少,特别是通过回收建筑和拆除(C&D)活动产生的废物。这项研究旨在通过量化回收C&D废物的具体碳节约潜力来弥补这一知识空白。它通过采用生命周期评估(LCA)并选择华南地区的粤港澳大湾区(GBA)进行案例研究来做到这一点。碳排放被视为体现在建筑材料中,通过回收,可以节省从原始材料中产生的等量碳。据估计,GBA产生了128.49公吨。2018年的C&D废物,这意味着92.26公吨的碳节约潜力。碳排放。该研究进一步了解了未来C&D废物的产生及其相应的碳节约潜力。开发了一种首创的动态方法,以模拟四种建筑开发方案下未来42年的节省潜力。根据不同的建筑增长率,2060年的碳节约潜力可达894.80公吨。下降到166.34公吨。这项研究可以帮助实现中国2060年碳中和目标,重点关注一个经济重要地区的不可忽视的部门。本文提出的方法也适用于全球其他地区,特别是在C&D废物数据不足的地方。
    Comparing with the enduring efforts to reduce carbon emissions in design, construction, and operation stages of a construction project, less attention has been paid to emission abatement potential in the end-of-life stage, particularly by recycling waste generated by construction and demolition (C&D) activities. This research aims to cover this knowledge void by quantifying the embodied carbon saving potential of recycling C&D waste. It does so by adopting a Life Cycle Assessment (LCA) and choosing the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) in South China for a case study. The carbon emission is treated as embodied in construction materials, by recycling which the equivalent amount of carbon generated from the virgin materials can be saved. It is estimated that the GBA produced 128.49 Mt. of C&D waste in 2018, which implies an embodied carbon saving potential of 92.26 Mt. carbon emissions. The research goes further to understand the future C&D waste generation and their corresponding embodied carbon saving potential. A first-of-its-kind dynamic approach is developed to simulate the future 42-year saving potential under four construction development scenarios. Depending on different construction growth rates, the embodied carbon saving potential in 2060 can be up to 894.80 Mt. and down to 166.34 Mt. This research can help achieve China\'s 2060 carbon neutral goal by focusing on a non-negligible sector in an economically important region. Methods proposed in this paper are also applicable to other regions worldwide, especially where C&D waste data is insufficient.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

  • 文章类型: Journal Article
    高风险神经母细胞瘤是一种侵袭性儿童癌症,其特征是化疗耐药率高,转移复发频繁。许多研究已经描述了神经母细胞瘤的遗传和表观遗传景观,但是由于突变负担普遍较低并且缺乏可操作的突变,通过使用靶向治疗来应用全面的个性化医疗方法的选择很少.因此,使用多药化疗仍然是目前治疗神经母细胞瘤的标准,这也在概念上限制了为这种疾病开发有效和广泛适用的个性化医疗方法的机会。然而,在这篇综述中,我们概述了通过对药物诱导的凋亡信号进行患者特异性模拟,根据个体肿瘤的特定分子特征定制化疗剂使用的潜在方法.通过整合有关肿瘤特异性像差的多层信息,包括表达和突变数据,这些模型有可能使多药物治疗方案中包含的化疗药物的选择合理化,并确保每个患者都能获得最佳疗效.
    High-risk neuroblastoma is an aggressive childhood cancer that is characterized by high rates of chemoresistance and frequent metastatic relapse. A number of studies have characterized the genetic and epigenetic landscape of neuroblastoma, but due to a generally low mutational burden and paucity of actionable mutations, there are few options for applying a comprehensive personalized medicine approach through the use of targeted therapies. Therefore, the use of multi-agent chemotherapy remains the current standard of care for neuroblastoma, which also conceptually limits the opportunities for developing an effective and widely applicable personalized medicine approach for this disease. However, in this review we outline potential approaches for tailoring the use of chemotherapy agents to the specific molecular characteristics of individual tumours by performing patient-specific simulations of drug-induced apoptotic signalling. By incorporating multiple layers of information about tumour-specific aberrations, including expression as well as mutation data, these models have the potential to rationalize the selection of chemotherapeutics contained within multi-agent treatment regimens and ensure the optimum response is achieved for each individual patient.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

       PDF(Pubmed)

公众号