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A Decentralized and TCAM-Aware Failure Recovery Model in Software Defined Data Center Networks

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Computers, Materials & Continua 2025年第1期82卷 1087-1107页

作者： Suheib Alhiyari Siti Hafizah AB hamid Nur Nasuha Daud Department of Computer System and Technology University of MalayaKuala Lumpur50603Malaysia

Link failure is a critical issue in large networks and must be effectively *** software-defined networks(SDN),link failure recovery schemes can be categorized into proactive and reactive *** schemes have longer recovery times while proactive schemes provide faster recovery but overwhelm the memory of switches by flow *** SDN adoption grows,ensuring efficient recovery from link failures in the data plane becomes *** particular,data center networks(DCNs)demand rapid recovery times and efficient resource utilization to meet carrier-grade *** paper proposes an efficient Decentralized Failure Recovery(DFR)model for SDNs,meeting recovery time requirements and optimizing switch memory resource *** DFR model enables switches to autonomously reroute traffic upon link failures without involving the controller,achieving fast recovery times while minimizing memory *** employs the Fast Failover Group in the OpenFlow standard for local recovery without requiring controller communication and utilizes the k-shortest path algorithm to proactively install backup paths,allowing immediate local recovery without controller intervention and enhancing overall network stability and *** employs flow entry aggregation techniques to reduce switch memory *** of matching flow entries to the destination host’s MAC address,DFR matches packets to the destination switch’s MAC *** reduces the switches’Ternary Content-Addressable Memory(TCAM)***,DFR modifies Address Resolution Protocol(ARP)replies to provide source hosts with the destination switch’s MAC address,facilitating flow entry aggregation without affecting normal network *** performance of DFR is evaluated through the network emulator Mininet 2.3.1 and Ryu 3.1 as SDN *** different number of active flows,number of hosts per edge switch,and different network sizes,the proposed model outperformed vario

关键词： Software defined networking failure detection failure recovery restoration protection TCAM size

A Survey of Link Failure Detection and Recovery in Software-Defined Networks

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Computers, Materials & Continua 2025年第1期82卷 103-137页

作者： Suheib Alhiyari Siti Hafizah AB hamid Nur Nasuha Daud Department of Software Engineering Universiti MalayaKuala Lumpur50603Malaysia

Software-defined networking(SDN)is an innovative paradigm that separates the control and data planes,introducing centralized network *** is increasingly being adopted by Carrier Grade networks,offering enhanced networkmanagement capabilities than those of traditional ***,because SDN is designed to ensure high-level service availability,it faces additional *** of themost critical challenges is ensuring efficient detection and recovery from link failures in the data *** failures can significantly impact network performance and lead to service outages,making resiliency a key concern for the effective adoption of *** the recovery process is intrinsically dependent on timely failure detection,this research surveys and analyzes the current literature on both failure detection and recovery approaches in *** survey provides a critical comparison of existing failure detection techniques,highlighting their advantages and ***,it examines the current failure recovery methods,categorized as either restoration-based or protection-based,and offers a comprehensive comparison of their strengths and ***,future research challenges and directions are discussed to address the shortcomings of existing failure recovery methods.

关键词： Software defined networking failure detection failure recovery restoration protection

Thermospheric neutral wind studies over the equatorial region:A review

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Earth and Planetary Physics 2025年第1期9卷 81-100页

作者： Siti Syazwani Nasuha Idahwati Sarudin Nurul Shazana Abdul hamid Ahmad Fairuz Omar School of Physics Universiti Sains Malaysia11800 USMPulau PinangMalaysia Department of Applied Physics Faculty of Science and TechnologyUniversiti Kebangsaan Malaysia43600 UKM BangiSelangorMalaysia Space Science Centre(ANGKASA) Institute of Climate ChangesUniversiti Kebangsaan Malaysia43600 UKM BangiSelangorMalaysia

Thermospheric neutral winds(TNWs)refer to the neutral gases in the thermosphere circulating as tides,which play a crucial role in the dynamics of the thermosphere-ionosphere system(TIS).Global geospace neutral winds,particularly over the magnetic equator,have been a subject of study for several ***,despite the known importance of neutral winds,a comprehensive understanding and characterization of the winds is still *** ground-based and satellite missions have provided valuable information on the contribution of neutral winds to the global atmospheric ***,efforts in the global monitoring of neutral winds are still lacking,and the drivers behind the behavior of TNWs as well as their influence on the TIS remain *** address these knowledge gaps in the global circulation of TNWs,it is crucial to develop a deep understanding of the neutral wind characteristics over different *** low-latitude equatorial region in particular has been observed to exert complex influences on TNWs because of the unique effects of the Earth’s magnetic field at the dip *** neutral winds over this region will provide valuable insights into the unique dynamics and processes that occur in this region,thereby enhancing our understanding of their role in the overall dynamics of the ***,through empirical observations,an improved ability to accurately model and predict the behavior of this region can be *** review article addresses challenges in understanding equatorial winds by reviewing historical measurements,current missions,and the interactions of ionospheric and thermospheric phenomena,emphasizing the need for comprehensive measurements to improve global atmospheric dynamics and weather forecasting.

关键词： thermospheric neutral wind thermosphere-ionosphere system dip equator equatorial region

Temporal dynamics of neonatal hypoxic-ischemic encephalopathy injuries on magnetic resonance imaging

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Neural Regeneration Research 2025年第11期20卷 3144-3150页

作者： Holly Flyger Samantha J.Holdsworth Alistair J.Gunn Laura Bennet hamid Abbasi Mātai Medical Research Institute Tairāwhiti GisborneNew Zealand Department of Anatomy&Medical Imaging Faculty of Medical and Health SciencesThe University of AucklandAucklandNew Zealand Center for Brain Research The University of AucklandAucklandNew Zealand Auckland Bioengineering Institute The University of AucklandAucklandNew Zealand

Moderate to severe perinatal hypoxic-ischemic encephalopathy occurs in~1 to 3/1000 live births in high-income countries and is associated with a significant risk of death or neurodevelopmental *** assessment is important to help identify highrisk infants,to help families,and to support appropriate interventions.A wide range of monitoring tools is available to assess changes over time,including urine and blood biomarkers,neurological examination,and *** present,magnetic resonance imaging is unique as although it is expensive and not suited to monitoring the early evolution of hypoxic-ischemic encephalopathy by a week of life it can provide direct insight into the anatomical changes in the brain after hypoxic-ischemic encephalopathy and so offers strong prognostic information on the long-term outcome after hypoxic-ischemic *** review investigated the temporal dynamics of neonatal hypoxic-ischemic encephalopathy injuries,with a particular emphasis on exploring the correlation between the prognostic implications of magnetic resonance imaging scans in the first week of life and their relationship to long-term outcome prediction,particularly for infants treated with therapeutic hypothermia.A comprehensive literature search,from 2016 to 2024,identified 20 pertinent *** review highlights that while the optimal timing of magnetic resonance imaging scans is not clear,overall,it suggests that magnetic resonance imaging within the first week of life provides strong prognostic *** challenges limit the timing consistency,particularly the need for intensive care and clinical ***,although most reports examined the prognostic value of scans taken between 4 and 10 days after birth,there is evidence from small numbers of cases that,at times,brain injury may continue to evolve for weeks after *** suggests that in the future it will be important to explore a wider range of times after hypo

关键词： magnetic resonance imaging neonatal hypoxic-ischemic encephalopathy neurodevelopmental outcomes prognostic biomarkers in neuroimaging scan timing therapeutic hypothermia

A multiscale material model for heterogeneous liquid droplets in solid soft composites

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Frontiers of Structural and Civil Engineering 2021年第5期15卷 1292-1299页

作者： hamid GHASEMI Department of Mechanical Engineering Arak University of TechnologyArak 38181-41167Iran

Liquid droplets in solid soft composites have been attracting increasing attention in biological *** contrary with conventional composites,which are made of solid elastic inclusions,available material models for composites including liquid droplets are for highly idealized configurations and do not include all material real *** are also all deterministic and do not address the uncertainties arising from droplet radius,volume fraction,dispersion and *** research revisits the available models for liquid droplets in solid soft composites and presents a multiscale computational material model to determine their elastic moduli,considering nearly all relevant uncertainties and heterogeneities at different length *** effects of surface tension at droplets interface,their volume fraction,size,size polydispersity and agglomeration on elastic modulus,are *** micromechanical material models are incorporated into the presented computational *** results clearly indicate both softening and stiffening effects of liquid droplets and show that the model can precisely predict the effective properties of liquid droplets in solid soft composites.

关键词： liquid in solid soft composite computational modeling multiscale model heterogeneity

Molecular dynamics simulation of structure H clathrate-hydrates of binary guest molecules

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Journal of Natural Gas Chemistry 2011年第6期20卷 577-584页

作者： hamid Erfan-Niya hamid Modarress Department of Chemical Engineering Amirkabir University of Technology

Molecular dynamics （MD） simulations are performed to study the stability of structure H clathrate-hydrates of methane＋large-molecule guest substance （LMGS） at temperatures of 270, 273, 278 and 280 K under canonical （NVT-） ensemble condition in a 3×3×3 structure H unit cell replica with 918 TIP4P water molecules. The studied LMGS are 2-methylbutane （2-MB）, 2,3-dimethylbutane （2,3-DMB）, neohexane （NH）, methylcyclohexane （MCH）, adamantane and tert-butyl methyl ether （TBME）. In the process of MD simulation, achieving equilibrium of the studied system is recognized by stability in calculated pressure for NVT-ensemble. So, for the accuracy of MD simulations, the obtained pressures are compared with the experimental phase diagrams. Therefore, the obtained equilibrium pressures by MD simulations are presented for studying the structure H clathrate-hydrates. The results show that the calculated temperature and pressure conditions by MD simulations are consistent with the experimental phase diagrams. Also, the radial distribution functions （RDFs） of host-host, host-guest and guest-guest molecules are used to analysis the characteristic configurations of the structure H clathrate-hydrate.

关键词： structure H clathrate-hydrate methane+large-molecule guest substance molecular dynamics stability radial distribution function

Application of consistent geometric decomposition theorem to dynamic finite element of 3D composite beam based on experimental and numerical analyses

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Frontiers of Structural and Civil Engineering 2020年第3期14卷 675-689页

作者： Iman FATTAHI hamid Reza MIRDAMADI hamid ABDOLLAHI Department of Mechanical Engineering Isfahan University of TechnologyIsfahan ***Iran

Analyzing static and dynamic problems including composite structures has been of high significance in research efforts and industrial *** this article,equivalent single layer approach is utilized for dynamic finite element procedures of 3D composite beam as the building block of numerous composite *** this model,both displacement and strain fields are decomposed into cross-sectional and longitudinal components,called consistent geometric decomposition ***,the model is discretized using finite clement *** local coordinate systems and a global one are defined to decouple mechanical degrees of ***,from the viewpoint of consistent geometric decomposition theorem,the transformation and element mass matrices for those systems are introduced here for the first *** same decomposition idea can be used for developing element stiffiness ***,comprehensive validations are conducted for the theory against experimental and numerical results in two case studies and for various conditions.

关键词： composite beam dynamic finite element degrees of freedom coupling experimental validation numerical validation

Coal pillar mechanics of violent failure in U.S. Mines

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International Journal of Mining Science and Technology 2017年第3期27卷 387-392页

作者： Maleki hamid Maleki Technologies Inc. Spokane WA 99223 USA

This paper seeks to enhance the understanding that the horizontal stresses build up and release during coal pillar loading and unloading(post-failure) drawing upon three decades of observations, geomechanical monitoring and numerical modeling in bump-prone U.S. mines. The focus is on induced horizontal stress in mine pillars and surrounding strata as highly stressed pillars punch into the roof and floor, causing shear failure and buckling of strata; under stiff stratigraphic units of some western US mines, these events could be accompanied by violent failure of pillar cores. Pillar punching eventually results in tensile stresses at the base of the pillar, facilitating transition into the post-failure regime; this transition will be nonviolent if certain conditions are met, notably the presence of interbedded mudstones with low shear strength properties and proper mine designs for controlling seismicity and dynamic loads. The study clearly shows high confining stress build-up in coal pillars resulting in up to twice higher peak vertical stress and high strain energy accumulations in some western US mines in comparison with peak stresses predicted using common empirical pillar design methods. It is the unstable release of this strain energy that can cause significant damage resulting from pillar dilation and ground movements. These forces are much greater than the capacity of most common internal support systems, resulting in horizontal stressinduced roof falls locally, in mines under unremarkable far-field horizontal stress. Attention should be placed on pillar designs as increasing support density may prove to be ineffective. This mechanism is analyzed using field measurements and generic finite-difference stress analyses. The study confirms the higher load carrying capacity of confinement-controlled coal seams in comparison with structurally controlled coal seams. Such significant differences in confining stresses are not taken into account when estimating peak pil

关键词： Rockburst and coal bumps Field measurements Stress analysis Mechanics Horizontal stress

Parallel resonance type fault current limiting circuit breaker

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High Voltage 2020年第1期5卷 76-82页

作者： hamid Radmanesh Seyed hamid Fathi Electrical Engineering Department Shahid Sattari Aeronautical University of Science and TechnologyTehranIran Electrical Engineering Department Amirkabir University of TechnologyTehranIran

The main goal of this study is introducing a novel fault current limiter based on parallel resonance structure(PRFCL)for high voltage *** normal mode,the PRFCL reactor is short-circuited via a rectifier bridge DC output voltage and LC resonance tank shows negligible impedance in the *** a fault,the rectifier bridge switches are turned off,so that the parallel resonance LC tank connects to the line with high *** impedance of the resonance structure can limit the fault current,*** is shown that the suggested PRFCL can act as a breaker and opens the line during the fault *** order to show the suggested PRFCL abilities,MATLAB software is used to simulate the normal and fault *** addition,a scale-down prototype is implemented to confirm the simulation *** comparative study shows that PRFCL has acceptable performance in normal and current limiting operation modes.

关键词： period fault limiting