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Analytical and Numerical Investigation of Two-Dimensional Heat Transfer with Periodic Boundary Conditions 带周期性边界条件的二维传热的分析和数值研究
IF 2.2 Q2 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2024-01-10 DOI: 10.3390/computation12010011
İ. Bağlan, Erman Aslan
A two-dimensional heat diffusion problem with a heat source that is a quasilinear parabolic problem is examined analytically and numerically. Periodic boundary conditions are employed. As the problem is nonlinear, Picard’s successive approximation theorem is utilized. We demonstrate the existence, uniqueness, and constant dependence of the solution on the data using the generalized Fourier method under specific conditions of natural regularity and consistency imposed on the input data. For the numerical solution, an implicit finite difference scheme is used. The results obtained from the analytical and numerical solutions closely match each other.
对一个二维热扩散问题进行了分析和数值研究,该问题带有一个热源,属于准线性抛物线问题。采用了周期性边界条件。由于问题是非线性的,因此采用了 Picard 逐次逼近定理。我们利用广义傅里叶方法,在输入数据的自然正则性和一致性的特定条件下,证明了解的存在性、唯一性和对数据的恒定依赖性。数值求解采用了隐式有限差分方案。分析和数值求解得出的结果非常吻合。
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引用次数: 0
Enhancement of Machine-Learning-Based Flash Calculations near Criticality Using a Resampling Approach 利用重采样方法改进基于机器学习的临界值闪存计算
IF 2.2 Q2 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2024-01-09 DOI: 10.3390/computation12010010
Eirini Maria Kanakaki, Anna Samnioti, V. Gaganis
Flash calculations are essential in reservoir engineering applications, most notably in compositional flow simulation and separation processes, to provide phase distribution factors, known as k-values, at a given pressure and temperature. The calculation output is subsequently used to estimate composition-dependent properties of interest, such as the equilibrium phases’ molar fraction, composition, density, and compressibility. However, when the flash conditions approach criticality, minor inaccuracies in the computed k-values may lead to significant deviation in the dependent properties, which is eventually inherited to the simulator, leading to large errors in the simulation. Although several machine-learning-based regression approaches have emerged to drastically accelerate flash calculations, the criticality issue persists. To address this problem, a novel resampling technique of the ML models’ training data population is proposed, which aims to fine-tune the training dataset distribution and optimally exploit the models’ learning capacity across various flash conditions. The results demonstrate significantly improved accuracy in predicting phase behavior results near criticality, offering valuable contributions not only to the subsurface reservoir engineering industry but also to the broader field of thermodynamics. By understanding and optimizing the model’s training, this research enables more precise predictions and better-informed decision-making processes in domains involving phase separation phenomena. The proposed technique is applicable to every ML-dominated regression problem, where properties dependent on the machine output are of interest rather than the model output itself.
闪存计算在储层工程应用中非常重要,尤其是在成分流模拟和分离过程中,它提供了在给定压力和温度下的相分布系数,即 k 值。计算输出随后用于估算与成分相关的相关特性,如平衡相的摩尔分数、成分、密度和可压缩性。然而,当闪蒸条件接近临界值时,计算 k 值中的微小误差可能会导致相关属性出现重大偏差,而这些偏差最终会遗传给模拟器,从而导致模拟出现较大误差。尽管已经出现了几种基于机器学习的回归方法,大大加快了闪存计算速度,但临界问题依然存在。为解决这一问题,我们提出了一种新颖的重采样技术,旨在微调训练数据集的分布,优化利用模型在各种闪光条件下的学习能力。结果表明,预测临界相行为结果的准确性大大提高,不仅为地下储层工程行业,而且为更广泛的热力学领域做出了宝贵贡献。通过了解和优化模型的训练,这项研究能够在涉及相分离现象的领域进行更精确的预测和更明智的决策过程。所提出的技术适用于所有以 ML 为主导的回归问题,在这些问题中,人们感兴趣的是依赖于机器输出的属性,而不是模型输出本身。
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引用次数: 0
Corporate Bankruptcy Prediction Models: A Comparative Study for the Construction Sector in Greece 企业破产预测模型:希腊建筑行业比较研究
IF 2.2 Q2 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2024-01-09 DOI: 10.3390/computation12010009
K. Toudas, S. Archontakis, P. Boufounou
This study focuses on testing the efficiency of alternative bankruptcy prediction models (Altman, Ohlson, Zmijewski) and on assessing the possible reasons that led to the confirmation or not of the prevailing model. Data from financial statements of listed (Greek) construction companies before the economic crisis were utilized. The results showed that Altman’s main predictive model as well as the revised models have low overall predictability for all three years before bankruptcy.
本研究的重点是测试替代破产预测模型(Altman、Ohlson、Zmijewski)的效率,并评估导致主流模型被证实或不被证实的可能原因。研究采用了经济危机前上市(希腊)建筑公司的财务报表数据。结果表明,Altman 的主要预测模型和修订模型对破产前三年的总体预测能力较低。
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引用次数: 0
Analysis of Effectiveness of Combined Surface Treatment Methods for Structural Parts with Holes to Enhance Their Fatigue Life 带孔结构件的组合表面处理方法对提高其疲劳寿命的效果分析
IF 2.2 Q2 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2024-01-08 DOI: 10.3390/computation12010008
Olexander Grebenikov, Andrii Humennyi, Serhii Svitlychnyi, Vasyl Lohinov, Valerii Matviienko
The typical and most widespread stress concentrators in the lower wing panels of aircraft are the drain holes located on the stringer vertical ribs. These are prime sources for the initiation and development of fatigue cracks, which lead to early failure of the wing structure. Therefore, improving fatigue life in these critical areas is one of the significant issues for research. Two combined methods of surface plastic treatment in the location around drain holes are discussed in this paper. Using the finite element method and ANSYS software, we created a finite element model and obtained nonlinear solution results in the case of tension in a plate with three holes. In addition, the development of residual stress due to the surface plastic treatment of the hole-adjacent areas was taken into account. In this paper, it is shown that after surface treatment of the corresponding areas of the holes, residual stress, which exceeds the yield stress for the plate material, is induced. When combined with alternative tensile stress, these reduce the amplitude of the local stresses, thus increasing the number of stress cycles before failure. The benefits of this technology were confirmed by fatigue test results, which include the fatigue failure types of the plates. Graphs showing the impact of applicable surface treatment combined methods on the number of cycles to failure were also plotted.
飞机下翼板上最典型、最普遍的应力集中点是位于纵梁竖肋上的排水孔。这些是疲劳裂纹产生和发展的主要源头,会导致机翼结构的早期失效。因此,提高这些关键部位的疲劳寿命是研究的重要课题之一。本文讨论了排水孔周围位置表面塑性处理的两种组合方法。利用有限元法和 ANSYS 软件,我们创建了一个有限元模型,并获得了带有三个孔的钢板在拉伸情况下的非线性求解结果。此外,我们还考虑了孔相邻区域的表面塑性处理导致的残余应力的发展。本文表明,在对孔的相应区域进行表面处理后,会产生超过板材料屈服应力的残余应力。当与替代拉应力相结合时,这些应力会降低局部应力的振幅,从而增加失效前的应力循环次数。疲劳测试结果(包括板材的疲劳失效类型)证实了这项技术的优势。此外,还绘制了图表,显示适用的表面处理组合方法对失效循环次数的影响。
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引用次数: 0
Thermal Analysis and Cooling Strategies of High-Efficiency Three-Phase Squirrel-Cage Induction Motors—A Review 高效三相鼠笼式感应电机的热分析和冷却策略--综述
IF 2.2 Q2 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2024-01-04 DOI: 10.3390/computation12010006
Yashwanth Reddy Konda, Vamsi Krishna Ponnaganti, Peram Venkata Sivarami Reddy, R. R. Singh, Paolo Mercorelli, Edison Gundabattini, D. Solomon
In recent times, there has been an increased demand for electric vehicles. In this context, the energy management of the electric motor, which are an important constituent of electric vehicles, plays a pivotal role. A lot of research has been conducted on the optimization of heat flow through electric motors, thus reducing the wastage of energy via heat. Futuristic power sources may increasingly rely on cutting-edge innovations like energy harvesting and self-powered induction motors. In this context, effective thermal management techniques are discussed in this paper. Importance was given to the potential energy losses, hotspots, the influence of overheating on the motor efficiency, different cooling strategies, certain experimental approaches, and power control techniques. Two types of thermal analysis computation methods, namely the lumped-parameter circuit method (LPCM) and the finite element method (FEM), are discussed. Also, this paper reviews different cooling strategies. The experimental research showed that the efficiency was greater by 11% with the copper rotor compared to the aluminum rotor. Each rotor type was reviewed based on the temperature rise and efficiency at higher temperatures. The water-cooling method reduced the working temperatures by 39.49% at the end windings, 41.67% at the side windings, and by a huge margin of 56.95% at the yoke of the induction motor compared to the air-cooling method; hence, the water-cooling method is better. Lastly, modern cooling strategies are proposed to provide an effective thermal management solution for squirrel-cage induction motors.
近来,人们对电动汽车的需求越来越大。在这种情况下,作为电动汽车重要组成部分的电动机的能源管理发挥着举足轻重的作用。人们对如何优化电动机的热流进行了大量研究,从而减少热能的浪费。未来的动力源可能会越来越依赖于能量收集和自供电感应电机等尖端创新技术。在此背景下,本文讨论了有效的热管理技术。本文重视潜在的能量损失、热点、过热对电机效率的影响、不同的冷却策略、某些实验方法和功率控制技术。本文讨论了两种热分析计算方法,即集合参数电路法(LPCM)和有限元法(FEM)。此外,本文还评述了不同的冷却策略。实验研究表明,铜转子的效率比铝转子高 11%。本文根据较高温度下的温升和效率对每种转子类型进行了评述。与空气冷却法相比,水冷却法使感应电动机端部绕组的工作温度降低了 39.49%,侧面绕组的工作温度降低了 41.67%,轭部的工作温度降低了 56.95%;因此,水冷却法的效果更好。最后,提出了现代冷却策略,为鼠笼式感应电机提供了有效的热管理解决方案。
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引用次数: 0
A New Mixed Fractional Derivative with Applications in Computational Biology 一种新的混合分数衍生物在计算生物学中的应用
IF 2.2 Q2 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2024-01-04 DOI: 10.3390/computation12010007
K. Hattaf
This study develops a new definition of a fractional derivative that mixes the definitions of fractional derivatives with singular and non-singular kernels. This developed definition encompasses many types of fractional derivatives, such as the Riemann–Liouville and Caputo fractional derivatives for singular kernel types, as well as the Caputo–Fabrizio, the Atangana–Baleanu, and the generalized Hattaf fractional derivatives for non-singular kernel types. The associate fractional integral of the new mixed fractional derivative is rigorously introduced. Furthermore, a novel numerical scheme is developed to approximate the solutions of a class of fractional differential equations (FDEs) involving the mixed fractional derivative. Finally, an application in computational biology is presented.
本研究提出了分数导数的新定义,它混合了具有奇异和非奇异内核的分数导数的定义。这个新定义涵盖了多种类型的分数导数,如奇异内核类型的黎曼-刘维尔分数导数和卡普托分数导数,以及非奇异内核类型的卡普托-法布里齐奥分数导数、阿坦加纳-巴莱阿努分数导数和广义哈塔夫分数导数。新混合分数导数的关联分数积分被严格引入。此外,还开发了一种新的数值方案,用于近似求解涉及混合分数导数的一类分数微分方程(FDE)。最后,介绍了在计算生物学中的应用。
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引用次数: 0
Implicit and Explicit Solvent Effects on the Global Reactivity and the Density Topological Parameters of the Preferred Conformers of Caespitate 溶剂对开司培的全局反应活性和首选构象的密度拓扑参数的隐性和显性影响
IF 2.2 Q2 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2024-01-03 DOI: 10.3390/computation12010005
Andrea Moreno-Ceballos, Maria Eugenia Castro, Norma A Caballero, Liliana Mammino, Francisco J. Melendez
In the search to cover the urgent need to combat infectious diseases, natural products have gained attention in recent years. The caespitate molecule, isolated from the plant Helichrysum caespititium of the Asteraceae family, is used in traditional African medicine. Caespitate is an acylphloroglucinol with biological activity. Acylphloroglucinols have attracted attention for treating tuberculosis due to their structural characteristics, highlighting the stabilizing effect of their intramolecular hydrogen bonds (IHBs). In this work, a conformational search for the caespitate was performed using the MM method. Posteriorly, DFT calculations with the APFD functional were used for full optimization and vibrational frequencies, obtaining stable structures. A population analysis was performed to predict the distribution of the most probable conformers. The calculations were performed in the gas phase and solution using the implicit SMD model for water, chloroform, acetonitrile, and DMSO solvents. Additionally, the multiscale ONIOM QM1/QM2 model was used to simulate the explicit solvent. The implicit and explicit solvent effects were evaluated on the global reactivity indexes using the conceptual-DFT approach. In addition, the QTAIM approach was applied to analyze the properties of the IHBs of the most energetically and populated conformers. The obtained results indicated that the most stable and populated conformer is in the gas phase, and chloroform has an extended conformation. However, water, acetonitrile, and DMSO have a hairpin shape. The optimized structures are well preserved in explicit solvent and the interaction energies for the IHBs were lower in explicit than implicit solvents due to non-covalent interactions formed between the solvent molecules. Finally, both methodologies, with implicit and explicit solvents, were validated with 1H and 13C NMR experimental data. In both cases, the results agreed with the experimental data reported in the CDCl3 solvent.
近年来,为满足防治传染病的迫切需要,天然产品备受关注。从菊科植物 Helichrysum caespititium 中分离出来的开司培特分子被用于非洲传统医药中。开司培特是一种具有生物活性的酰基氯葡萄糖醇。酰基氯葡萄糖苷因其结构特征而在治疗结核病方面备受关注,其中突出的是其分子内氢键(IHB)的稳定作用。在这项工作中,采用 MM 方法对头孢烷酸进行了构象搜索。随后,利用 APFD 函数进行了 DFT 计算,以全面优化和振动频率,从而获得了稳定的结构。为了预测最可能构象的分布,还进行了群体分析。计算是在气相和溶液中进行的,使用的是针对水、氯仿、乙腈和 DMSO 溶剂的隐式 SMD 模型。此外,还使用多尺度 ONIOM QM1/QM2 模型模拟显式溶剂。使用概念-DFT 方法评估了隐式和显式溶剂对全局反应性指数的影响。此外,还采用 QTAIM 方法分析了能量最高、最多的构象的 IHB 特性。结果表明,气相中的构象最稳定、最多,氯仿具有扩展构象。然而,水、乙腈和二甲基亚砜具有发夹形。优化后的结构在显式溶剂中得到了很好的保留,由于溶剂分子之间形成的非共价相互作用,IHB 在显式溶剂中的相互作用能低于隐式溶剂。最后,用 1H 和 13C NMR 实验数据验证了隐式溶剂和显式溶剂的两种方法。在这两种情况下,结果都与在 CDCl3 溶剂中报告的实验数据一致。
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引用次数: 0
LSTM Reconstruction of Turbulent Pressure Fluctuation Signals 湍流压力波动信号的 LSTM 重构
IF 2.2 Q2 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2024-01-01 DOI: 10.3390/computation12010004
Konstantinos Poulinakis, Dimitris Drikakis, I. Kokkinakis, S. Spottswood, T. Dbouk
This paper concerns the application of a long short-term memory model (LSTM) for high-resolution reconstruction of turbulent pressure fluctuation signals from sparse (reduced) data. The model’s training was performed using data from high-resolution computational fluid dynamics (CFD) simulations of high-speed turbulent boundary layers over a flat panel. During the preprocessing stage, we employed cubic spline functions to increase the fidelity of the sparse signals and subsequently fed them to the LSTM model for a precise reconstruction. We evaluated our reconstruction method with the root mean squared error (RMSE) metric and via inspection of power spectrum plots. Our study reveals that the model achieved a precise high-resolution reconstruction of the training signal and could be transferred to new unseen signals of a similar nature with extremely high success. The numerical simulations show promising results for complex turbulent signals, which may be experimentally or computationally produced.
本文涉及应用长短期记忆模型(LSTM)从稀疏(缩小)数据中高分辨率重建湍流压力波动信号。该模型的训练使用了平板上高速湍流边界层的高分辨率计算流体动力学(CFD)模拟数据。在预处理阶段,我们使用三次样条函数来提高稀疏信号的保真度,随后将其输入 LSTM 模型以进行精确重建。我们通过均方根误差 (RMSE) 指标和功率谱图检查评估了我们的重建方法。我们的研究表明,该模型实现了对训练信号的精确高分辨率重构,并能以极高的成功率转移到新的未见类似性质的信号上。数值模拟结果表明,对于可能通过实验或计算产生的复杂湍流信号,该模型具有良好的应用前景。
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引用次数: 0
Design of Inhibitors That Target the Menin-Mixed-Lineage Leukemia Interaction. 设计靶向 Menin-Mixed-Lineage 白血病相互作用的抑制剂
IF 1.9 Q2 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2024-01-01 Epub Date: 2023-12-27 DOI: 10.3390/computation12010003
Moses N Arthur, Kristeen Bebla, Emmanuel Broni, Carolyn Ashley, Miriam Velazquez, Xianin Hua, Ravi Radhakrishnan, Samuel K Kwofie, Whelton A Miller

The prognosis of mixed-lineage leukemia (MLL) has remained a significant health concern, especially for infants. The minimal treatments available for this aggressive type of leukemia has been an ongoing problem. Chromosomal translocations of the KMT2A gene are known as MLL, which expresses MLL fusion proteins. A protein called menin is an important oncogenic cofactor for these MLL fusion proteins, thus providing a new avenue for treatments against this subset of acute leukemias. In this study, we report results using the structure-based drug design (SBDD) approach to discover potential novel MLL-mediated leukemia inhibitors from natural products against menin. The three-dimensional (3D) protein model was derived from Protein Databank (Protein ID: 4GQ4), and EasyModeller 4.0 and I-TASSER were used to fix missing residues during rebuilding. Out of the ten protein models generated (five from EasyModeller and I-TASSER each), one model was selected. The selected model demonstrated the most reasonable quality and had 75.5% of residues in the most favored regions, 18.3% of residues in additionally allowed regions, 3.3% of residues in generously allowed regions, and 2.9% of residues in disallowed regions. A ligand library containing 25,131 ligands from a Chinese database was virtually screened using AutoDock Vina, in addition to three known menin inhibitors. The top 10 compounds including ZINC000103526876, ZINC000095913861, ZINC000095912705, ZINC000085530497, ZINC000095912718, ZINC000070451048, ZINC000085530488, ZINC000095912706, ZINC000103580868, and ZINC000103584057 had binding energies of -11.0, -10.7, -10.6, -10.2, -10.2, -9.9, -9.9, -9.9, -9.9, and -9.9 kcal/mol, respectively. To confirm the stability of the menin-ligand complexes and the binding mechanisms, molecular dynamics simulations including molecular mechanics Poisson-Boltzmann surface area (MM/PBSA) computations were performed. The amino acid residues that were found to be potentially crucial in ligand binding included Phe243, Met283, Cys246, Tyr281, Ala247, Ser160, Asn287, Asp185, Ser183, Tyr328, Asn249, His186, Leu182, Ile248, and Pro250. MI-2-2 and PubChem CIDs 71777742 and 36294 were shown to possess anti-menin properties; thus, this justifies a need to experimentally determine the activity of the identified compounds. The compounds identified herein were found to have good pharmacological profiles and had negligible toxicity. Additionally, these compounds were predicted as antileukemic, antineoplastic, chemopreventive, and apoptotic agents. The 10 natural compounds can be further explored as potential novel agents for the effective treatment of MLL-mediated leukemia.

混合系白血病(MLL)的预后一直是一个重大的健康问题,尤其是对婴儿而言。对这种侵袭性白血病的治疗方法极少,一直是个问题。KMT2A 基因的染色体易位被称为 MLL,它能表达 MLL 融合蛋白。一种名为 Menin 的蛋白质是这些 MLL 融合蛋白的重要致癌辅助因子,从而为治疗这一急性白血病亚型提供了新的途径。在本研究中,我们报告了利用基于结构的药物设计(SBDD)方法从天然产物中发现潜在的新型 MLL 介导的白血病抑制剂的结果。三维(3D)蛋白质模型来自蛋白质数据库(Protein Databank)(蛋白质编号:4GQ4),在重建过程中使用了 EasyModeller 4.0 和 I-TASSER 来修复缺失的残基。在生成的 10 个蛋白质模型(EasyModeller 和 I-TASSER 各生成 5 个)中,选出了一个模型。所选模型的质量最为合理,75.5% 的残基位于最有利的区域,18.3% 的残基位于额外允许的区域,3.3% 的残基位于慷慨允许的区域,2.9% 的残基位于不允许的区域。除了三种已知的 menin 抑制剂外,还使用 AutoDock Vina 虚拟筛选了一个配体库,其中包含来自中文数据库的 25,131 个配体。前 10 个化合物包括 ZINC000103526876、ZINC000095913861、ZINC000095912705、ZINC000085530497、ZINC000095912718、ZINC000070451048、ZINC000085530488、ZINC000095912706、ZINC000103580868 和 ZINC000103584057,它们的结合能分别为 -11.0、-10.7、-10.6、-10.2、-10.2、-9.9、-9.9、-9.9、-9.9 和 -9.9 kcal/mol。为了证实门宁配体复合物的稳定性和结合机制,研究人员进行了分子动力学模拟,包括分子力学泊松-波尔兹曼表面积(MM/PBSA)计算。研究发现,在配体结合过程中可能起关键作用的氨基酸残基包括 Phe243、Met283、Cys246、Tyr281、Ala247、Ser160、Asn287、Asp185、Ser183、Tyr328、Asn249、His186、Leu182、Ile248 和 Pro250。MI-2-2 以及 PubChem CID 71777742 和 36294 被证明具有抗menin特性;因此,有必要通过实验确定已鉴定化合物的活性。本文鉴定的化合物具有良好的药理学特征,毒性可忽略不计。此外,这些化合物还被预测为抗白血病、抗肿瘤、化学预防和细胞凋亡剂。这 10 种天然化合物可作为有效治疗 MLL 介导的白血病的潜在新型药物进行进一步的研究。
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引用次数: 0
MSVR & Operator-Based System Design of Intelligent MIMO Sensorless Control for Microreactor Devices 基于 MSVR 和操作员的微反应器设备智能 MIMO 无传感器控制系统设计
IF 2.2 Q2 MATHEMATICS, INTERDISCIPLINARY APPLICATIONS Pub Date : 2023-12-25 DOI: 10.3390/computation12010002
Tatsuma Kato, Kosuke Nishizawa, Mingcong Deng
Recently, microreactors, which are tubular reactors capable of fast and highly efficient chemical reactions, have attracted attention. However, precise temperature control is required because temperature changes due to reaction heat can cause reactions to proceed differently from those designed. In a previous study, a single-input/output nonlinear control system was proposed using a model in which the microreactor is divided into three regions and the thermal equation is formulated considering the temperature gradient, but it could not control two different temperatures. In this paper, a multi-input, multi-output nonlinear control system was designed using operator theory. On the other hand, when the number of parallel microreactors is increased, a sensorless control method using M–SVR with a generalized Gaussian kernel was incorporated into the MIMO nonlinear control system from the viewpoint of cost reduction, and the effectiveness of the proposed method was confirmed via experimental results.
最近,能够进行快速、高效化学反应的管状反应器--微反应器备受关注。然而,由于反应热引起的温度变化会导致反应的进行与设计不同,因此需要精确的温度控制。在之前的研究中,有人提出了一种单输入/输出非线性控制系统,使用的模型是将微反应器分为三个区域,并考虑温度梯度制定热方程,但该系统无法控制两个不同的温度。本文利用算子理论设计了一种多输入、多输出非线性控制系统。另一方面,当并行微反应器的数量增加时,从降低成本的角度出发,将使用广义高斯核的 M-SVR 的无传感器控制方法纳入 MIMO 非线性控制系统,并通过实验结果证实了所提方法的有效性。
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引用次数: 0
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Computation
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