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Estimating Critical Clearing Time of Grid Faults Using DA of State-Reduction Model of Power Systems

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 807-820页

作者： Yang Liu Zhongyang Chen huanjin Yao Lin Yi Q.h.Wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510640China China Southern Power Grid Research Institute Guangzhou 510663China

This paper proposes a critical clearing time (CCT) estimation method by the domain of attraction (DA) of a state-reduction model of power systems using sum of squares (SOS) programming. By exploiting the property of the Jacobian matrix and the structure of the boundary of the DA, it is found the DA of the state-reduction model and that of the full model of a power system are topological isomorphism. There are one-to-one correspondence relationships between the number of equilibrium points, the type of equilibrium points, and solutions of the two system models. Based on these findings, an expanding interior algorithm is proposed with SOS programming to estimate the DA of the state-reduction model. State trajectories of the full model can be transformed to those of the state-reduction model by orthogonal or equiradius projection. In this way, CCT of a grid fault is estimated with the DA of the state-reduction model. The calculational burden of SOS programming in the DA estimation using the state-reduction model is rather small compared with using the full model. Simulation results show the proposed expanding interior algorithm is able to provide a tight estimation of DA of power systems with higher accuracy and lower time costs.

关键词： Critical clearing time domain of attraction expanding interior algorithm state-reduction model SOS programming

MPDP: A Probabilistic Architecture for Microservice Performance Diagnosis and Prediction

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Computer Systems Science & Engineering 2024年第5期48卷 1273-1299页

作者： Talal h.Noor Department of Computer Science College of Computer Science and EngineeringTaibah UniversityMadinah42353Saudi Arabia

In recent years,container-based cloud virtualization solutions have emerged to mitigate the performance gap between non-virtualized and virtualized physical ***,there is a noticeable absence of techniques for predicting microservice performance in current research,which impacts cloud service users’ability to determine when to provision or de-provision *** microservice performance poses challenges due to overheads associated with actions such as variations in processing time caused by resource contention,which potentially leads to user *** this paper,we propose,develop,and validate a probabilistic architecture named Microservice Performance Diagnosis and Prediction(MPDP).MPDP considers various factors such as response time,throughput,CPU usage,and othermetrics to dynamicallymodel interactions betweenmicroservice performance indicators for diagnosis and *** experimental data fromourmonitoring tool,stakeholders can build various networks for probabilistic analysis ofmicroservice performance diagnosis and prediction and estimate the best microservice resource combination for a given Quality of Service(QoS)*** generated a dataset of microservices with 2726 records across four benchmarks including CPU,memory,response time,and throughput to demonstrate the efficacy of the proposed MPDP *** validate MPDP and demonstrate its capability to predict microservice *** compared various Bayesian networks such as the Noisy-OR Network(NOR),Naive Bayes Network(NBN),and Complex Bayesian Network(CBN),achieving an overall accuracy rate of 89.98%when using CBN.

关键词： Cloud computing microservices monitoring performance QoS diagnosis prediction Bayesian network

Inhibiting the oligomerization of mycobacterial DNA-directed RNA polymerase(RNAP)using natural compound via in-silico techniques

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Medicine in Novel Technology and Devices 2024年第1期21卷 97-109页

作者： Ehssan h.Moglad Department of Pharmaceutics College of PharmacyPrince Sattam Bin Abdulaziz UniversityP.O.Box 173 Alkharj 11942Saudi Arabia Department of Microbiology and Parasitology Institute of Medicinal and Aromatic Plants ResearchThe National Center for ResearchP.O.Box 2404KhartoumSudan

Mycobacterium tuberculosis(Mtb)is responsible for the spread of tuberculosis(TB).The current study employed virtual screening of 2569 natural compounds against the DNA-directed RNA polymerase(RNAP)of Mtb to identify the possible binders that can inhibit its *** in-silico methodology included molecular docking to the compounds,further,the stability and flexibility of the best complexes were studied using molecular dynamics simulation,the MM/GBSA binding free energy technique with energy decomposition,PCA,FEL,steered MD simulation,and umbrella *** virtual screenings were conducted for the five RNAP subunits(chains A,B,C,D,and E)to identify a compound capable of inhibiting RNAP oligomerization.A promising compound,isoestradiol 3-benzoate,exhibited a low binding score(−7.28kcal/mol to−8.21kcal/mol)and showed binding ability with all subunits of the ***,the five complexes with isoestradiol 3-benzoate were selected for molecular dynamics simulation ***,RMSD showed that isoestradiol 3-benzoate bound with chain E showed the lowest RMSD of 0.49nm,while with chains A and B it had the most stable and consistent conformations with RMSD of 1.75nm and 1.2nm,*** h-bond between isoestradiol 3-benzoate and chains C and E showed the highest occupancy(58.27%,45.33%,and 50.80%,42.25%,11.75%).Moreover,the MMPBSA technique showed that isoestradiol 3-benzoate had a strong association with chains B and C(ΔGbind=−126.25±2.03 and−129.27±2.25).Additionally,free energy decomposition,PCA,FEL-steered MD simulation,and umbrella sampling were also performed to validate the association of the ligand with the *** 3-benzoate binds strongly to chains B and E;therefore,it should be considered as viable candidate for inhibiting the formation of RNAP protein complex,concluded in this study.

关键词： Mycobacterium tuberculosis DNA-Directed RNA polymerase Docking Steered MD simulation Natural compounds Binding free energy Umbrella sampling

Flexible neural probes:a review of the current advantages,drawbacks,and future demands

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2024年第2期25卷 153-167页

作者： Sara PIMENTA Joao R.FREITAS Joséh.CORREIA CMEMS-UMinho University of MinhoGuimarães4800-058Portugal LABBELS-Associate Laboratory Braga/GuimarãesPortugal

Brain diseases affect millions of people and have a huge social and economic *** use of neural probes for studies in animals has been the main approach to increasing knowledge about neural network ***,neuroscientists are trying to develop new and more effective therapeutic approaches to treating neurological *** implementation of neural probes with multifunctionalities(electrical,optical,and fluidic interactions)has been increasing in the last few years,leading to the creation of devices with high temporal and spatial *** the applicability of,and elements integrated into,neural probes has also led to the necessity to create flexible interfaces,reducing neural tissue damage during probe implantation and increasing the quality of neural acquisition *** this paper,we review the fabrication,characterization,and validation of several types of flexible neural probes,exploring the main advantages and drawbacks of these ***,future developments and applications are ***,this review aims to present the currently available flexible devices and future appropriate avenues for development as possible guidance for future engineered devices.

关键词： Brain knowledge Flexible interface Multifunctional probe

Energy Design and Optimization of Greenhouse by Natural Convection

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Fluid Dynamics & Materials Processing 2024年第8期20卷 1903-1913页

作者： h.Benzzine h.Labrim Aouatif Saad Y.Achour D.Zejli R.El Bouayadi Advanced Systems Engineering Laboratory(ASELab) National School of Applied SciencesIbn Tofail UniversityKenitraMorocco

This study addresses the pressing need for energy-efficient greenhouse management by focusing on the innovative application of natural *** primary objective of this study is to evaluate various ventilation strategies to enhance energy efficiency and optimize crop production in agricultural *** advanced numerical simulation tools,the study conducts a comprehensive assessment of natural ventilation’s effectiveness under real-world *** results underscore the crucial role of the stack effect and strategic window positioning in greenhouse cooling,providing valuable insights for greenhouse *** findings shed light on the significant benefits of optimized ventilation and also offer practical implications for improving greenhouse design,ensuring sustainable and efficient agricultural *** study demonstrated energy savings in cooling from November to April,with a maximum saving of 680 kWh in March,indicating the effectiveness of strategically positioning windows to leverage the stack *** approach enhances plant growth and reduces the need for costly cooling systems,thereby improving overall energy efficiency and lowering operational expenses.

关键词： Energy greenhouse cooling natural ventilation simulation temperature

In situ TEM investigation of electron irradiation and aging-induced high-density nanoprecipitates in an Mg-10Gd-3Y-1Zn-0.5Zr alloy

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Journal of Magnesium and Alloys 2024年第5期12卷 1841-1853页

作者： M.Lv h.L.Ge Q.Q.Jin X.h.Shao Y.T.Zhou B.Zhang X.L.Ma Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Materials Science and Engineering Research Center Guangxi University of Science and TechnologyLiuzhou 545006China

In-situ electron irradiation and aging are applied to introduce high-density precipitates in an Mg-10Gd-3Y-1Zn-0.5Zr(GWZ1031K,wt.%)alloy to improve the *** results show that the hardness of the Mg alloy after irradiation for 10 h and aging for 9 h at 250℃ is 1.64 GPa,which is approximately 64% higher than that of the samples before being *** is mainly attributed to γ'precipitates on the basal plane after irradiation and the high-density nanoscale β'precipitates on the prismatic plane after aging,which should be closely related to the irradiation-induced homogenous *** latter plays a key role in precipitation *** result paves a way to improve the mechanical properties of metallic materials by tailoring the precipitation through irradiation and aging.

关键词： Mg alloy Electron beam irradiation hardening Precipitates In-situ TEM

A high-Order Localized Artificial Diffusivity Scheme for Discontinuity Capturing on 1D Drift-Flux Models for Gas-Liquid Flows

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Advances in Applied Mathematics and Mechanics 2024年第1期16卷 47-74页

作者： Adyllyson h.Nascimento Eugenio S.Rosa Department of Energy School of Mechanical EngineeringUniversity of CampinasCampinasBrazil

A computational code is developed for the numerical solution of onedimensional transient gas-liquid flows using drift-flux models,in isothermal and also with phase change *** these two-phase models,classical upwind schemes such as Roe-and Godunov-type schemes are generally difficult to derive and expensive to use,since there are no treatable analytic expressions for the Jacobian matrix,eigenvalues and eigenvectors of the system of *** the other hand,the highorder compact finite difference scheme becomes an attractive alternative on these occasions,as it does not make use of any wave propagation information from the system of *** present paper extends the localized artificial diffusivity method for high-order compact finite difference schemes to solve two-phase flows with *** numerical method has simple formulation,straightforward implementation,low computational cost and,most importantly,*** numerical methodology proposed is validated by solving several numerical examples given in the *** simulations are sixth-order accurate and it is shown that the proposed numerical method provides accurate approximations of shock waves and contact *** is an essential property for simulations of realistic mass transport problems relevant to operations in the petroleum industry。

关键词： Compressible two-phase flows drift-flux model localized artificial diffusivity highorder numerical methods

Nonlinear boundary control problem of hyperbolic systems

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Journal of Control and Decision 2024年第1期11卷 73-83页

作者： A.Bouhamed A.El Kabouss h.Bouzahir ISTI Lab Ibn Zohr UniversityENSAAgadirMorocco Faculty of sciences Moulay Ismail UniversityMeknesMorocco

The paper is devoted to the study of optimal control of a hyperbolic system,where the control enters the system through the *** hyperbolic system is the wave equation on a smooth and open domain,where the boundary condition involves the normal derivative at the boundary of z,the time derivative of z times a constant k,and a nonlinear term ***,z is the state and u is the control,satisfying some boundedness condition depending on *** functional cost consists of the energy and the difference between the solution of the system at final time,and a desired state in *** a closed convex set,we prove the existence of an optimal control that minimises the cost functional using a priori ***,using the differentiability of the cost functional with respect to the control,we establish the characterisation by deriving necessary conditions that an optimal control must satisfy.A numerical approach is successfully illustrated by simulations.

关键词： Non-linear system hyperbolic system boundary control optimal control controllability

Implicit Function Based Open-loop Analysis Method for Detecting the SSR Using Identified System Parameters

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CSEE Journal of Power and Energy Systems 2024年第5期10卷 2016-2026页

作者： Luonan Qiu Tianhao Wen Yang Liu Q.h.Wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510640China

This paper proposes an implicit function based open-loop analysis method to detect the subsynchronous resonance(SSR),including asymmetric subsynchronous modal attraction(ASSMA)and asymmetric subsynchronous modal repulsion(ASSMR),of doubly-fed induction generator based wind farms(DFIG-WFs)penetrated power *** some important parameters of DFIG-WF are difficult to obtain,reinforcement learning and least squares method are applied to identify those important *** predicting the location of closed-loop subsynchronous oscillation(SSO)modes based on the calculation of partial differentials of characteristic equation,both ASSMA and ASSMR can be *** proposed method in this paper can select SSO modes which move to the right half complex planes as control parameters ***,the proposed open-loop analysis method is adaptive to parameter *** studies are carried out on the 4-machine 11-bus power system to verify properties of the proposed method.

关键词： Open-loop modal analysis reinforcement learning based parameter identification subsynchronous resonance