Journal articles: 'Load and flow time'

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Samet, Haidar, and Morteza Khorshidsavar. "Analytic time series load flow." Renewable and Sustainable Energy Reviews 82 (February 2018): 3886–99. http://dx.doi.org/10.1016/j.rser.2017.10.084.

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Mesa, Fernando, Pedro Pablo Cardenas Alzate, and Carlos Alberto Rodriguez Varela. "Probabilistic load flow with load estimation using time series techniques and neural networks." Contemporary Engineering Sciences 10 (2017): 1153–61. http://dx.doi.org/10.12988/ces.2017.710132.

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Ghatak, Ujjwal, V. Mukherjee, Almoataz Y. Abdelaziz, Shady H. E. Abdel Aleem, and Hala M. Abdel Mageed. "Time-Efficient Load Flow Technique for Radial Distribution Systems with Voltage-Dependent Loads." International Journal on Energy Conversion (IRECON) 6, no. 6 (November 30, 2018): 196. http://dx.doi.org/10.15866/irecon.v6i6.15765.

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Choudhury, Anamitra Roy, Syamantak Das, Naveen Garg, and Amit Kumar. "Rejecting jobs to minimize load and maximum flow-time." Journal of Computer and System Sciences 91 (February 2018): 42–68. http://dx.doi.org/10.1016/j.jcss.2017.07.006.

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et al., Deepu. "Convergence time aware switch migration algorithm for SDN (CTSMA) cloud datacenter." International Journal of ADVANCED AND APPLIED SCIENCES 9, no. 8 (August 2022): 100–108. http://dx.doi.org/10.21833/ijaas.2022.08.013.

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Multi-controller deployment in a software-defined network improves the system's stability and scalability. However, since network traffic fluctuates, it presents a new problem for balancing loads on remote controllers. Controller Adaption and Migration Decision (CAMD) and Dynamic and Adaptive Load Balancing (DALB) frameworks are developed for efficient balancing of load on the controller to solve the problem of controller overload due to dynamic network traffic. CAMD was considered to be more efficient than DALB, but when the network is more dynamic, and the incoming traffic flow is elephant flow this leads to the overall reduction in system performance. This study proposed a Convergence Time aware Switch Migration Algorithm (CTSMA) that solved the network challenge when the network is more dynamic and incoming traffic flow is more. This research developed an enhanced switch migration algorithm to address the network difficulty of dynamically changing incoming load. Because of the imbalanced distribution of load on the controllers, processing flows will have longer response times and the controllers' throughput will be reduced. Switch migration is the best method of resolving the issue. Present techniques, on the other hand, focus solely on load balancing performance while ignoring migration efficiency, thereby leading to large migration costs and excessive control overheads. To increase the load and migration efficiency of controllers, this research work developed a convergence time aware switch migration method. To find the group of underloaded controllers in the network, the improved framework looked at controller volatility and average load status. Performance comparison indicators included controller throughput, reaction time, and convergence time. According to simulation studies, CTSMA outperforms CAMD by cutting controller reaction time by roughly 6.1%, increasing controller throughput by 8.0% on average, keeping a decent load balancing rate, lowering migration costs, and maintaining the best load balancing rate.

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Moreno Lopez de Saa, M. A., and J. Usaola Garcia. "Three-phase harmonic load flow in frequency and time domains." IEE Proceedings - Electric Power Applications 150, no. 3 (2003): 295. http://dx.doi.org/10.1049/ip-epa:20030250.

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Liu, Chun Rong, and Dao Lin Xu. "Bed Load Transport under Complex Flow." Advanced Materials Research 255-260 (May 2011): 3589–93. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.3589.

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In this paper, the backward-facing step flow and the sediment transport downstream step were studied experimentally. The critical incipient bed shear velocity is obtained by the results of bed shear velocity and sediment incipient probability. It was found that the critical incipient bed shear velocity depends on the flow structures under the complex flow. By using the new critical incipient bed shear obtained in this paper and calculating the Shields parameter based on instantaneous bed shear velocity, the bed load sediment transport rate downstream step was given. The time history of the bed profile downstream step was calculated by bed load sediment transport rate and compared that obtained by the digital images. Good agreement was observed.

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Venkatasivanagaraju, S., and M. Venkateswara Rao. "Polar Coordinates based N-R Method for Load Modelling in Electrical Power Distribution Systems." WSEAS TRANSACTIONS ON POWER SYSTEMS 16 (December 31, 2021): 354–60. http://dx.doi.org/10.37394/232016.2021.16.35.

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In this paper, load modelling has been done in electrical distribution system using local real time test data. This distribution system supplies base loads, residential, industrial, commercial and composite loads. Using power and current-mismatch functions in polar form, a comprehensive framework for applying the Newton–Raphson method to solve power flow problems is presented. The Newton–Raphson approach for solving power flow problems can be applied in six different ways using these two mismatch functions. For load (PQ)buses and generator (PV) buses, we propose a theoretical framework for analyzing these versions. In addition, we compare newly created versions of the Newton power flow method to current variants in this study. Numerical studies on distribution networks are used to study the convergence behavior of all approaches. The measurements are formed for short term load forecasting with different types of realistic loads such as base loads, residential, industrial, commercial and composite loads. The long-term load forecasting and their losses also has been performed along with short term load forecasting. The results are obtained and validated through MATLAB.

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Kubba, Hassan Abdullah, and Yasser Falah Hassan. "A Real-Time Fuzzy Load Flow and Contingency Analysis Based on Gaussian Distribution System." Journal of Engineering 21, no. 8 (August 1, 2015): 55–70. http://dx.doi.org/10.31026/j.eng.2015.08.04.

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Fuzzy logic is used to solve the load flow and contingency analysis problems, so decreasing computing time and its the best selection instead of the traditional methods. The proposed method is very accurate with outstanding computation time, which made the fuzzy load flow (FLF) suitable for real time application for small- as well as large-scale power systems. In addition that, the FLF efficiently able to solve load flow problem of ill-conditioned power systems and contingency analysis. The FLF method using Gaussian membership function requires less number of iterations and less computing time than that required in the FLF method using triangular membership function. Using sparsity technique for the input Ybus sparse matrix data gives reduction in overall computation time and storage requirements. The performance of the used methods had been tested on two typical test systems being the IEEE 14-bus and 30-bus systems in addition to the 362-bus Iraqi National Grid. All the obtained results under normal operating conditions show that the computation time of the fuzzy Load Flow (FLF) is less than the fast decoupled load flow (FDLF).

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Godbole, Prachi, and Sincy George. "A Novel Algorithm for Optimal Harmonic Load Flow including Harmonic Compensation." Engineering, Technology & Applied Science Research 13, no. 1 (February 5, 2023): 10093–99. http://dx.doi.org/10.48084/etasr.5475.

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Load flow analysis is widely used for finding voltage at various parts of a large, interconnected power system. The exponential increase in the use of power electronic devices and the noticeable percentage of integration of renewable energy sources in modern power systems result in the occurrence of non-sinusoidal voltages at various parts of the power system. By reformation of the Newton-Raphson load flow method, a few harmonic load flow algorithms have been developed for modern transmission systems. However, for larger transmission systems, complexity and heavy computational burden are often encountered in the load flow solution process due to the increased size of the Jacobean matrix that further increases with multiple non-linear load buses and compensation requirements. This leads to convergence problems and increased execution time. In this paper, an optimal harmonic load flow algorithm is proposed, that employs a modified PSO technique to select control variables and the harmonic load flow method to find solutions for load flow analysis with a reduced size of the Jacobean matrix. The formulated method uses a simple technique to take into account nonlinear loads and results in faster convergence. The novelty of the algorithm is that an optimal load flow solution with the desired amount of reactive and harmonic compensation currents is obtained. The algorithm can help in getting load flow solutions in future power systems with distorted voltage and currents with compensation. The performance of the proposed algorithm is tested on a modified IEEE 30-bus system with multiple non-linear load buses and is validated with the Simulink model of the system.

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Zhao, Weiqiang, Xingxing Huang, Mengqi Yang, Haixia Yang, Huili Bi, Qilian He, and Zhengwei Wang. "Flow-Induced Dynamic Behavior of Head-Cover Bolts in a Prototype Pump-Turbine during Load Rejection." Machines 10, no. 12 (November 28, 2022): 1130. http://dx.doi.org/10.3390/machines10121130.

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In order to ensure stable grid operatiFon and improve power quality, active or passive load rejection of pumped storage power stations (PSPS) inevitably occurs from time to time. The rapid closing of the guide vanes will cause drastic changes in pressure pulsations in the flow channel of the pump-turbine (PT) unit. The high-level pressure pulsations during load rejection transfer to the entire flow passage of the PT unit and generate strong vibrations on the head-cover and the connecting bolts. In this study, the 1D/3D joint simulation of the pipeline in a pumped storage power station and the turbine flow channels including the flow domains of the runner, crown chamber, band chamber, upper and lower labyrinths and pressure balance tubes is carried out first. Then, by applying the calculated pressure loads on the head-cover, stay vanes and bottom ring of the PT unit, the flow-induced dynamic behavior of the structures including the head-cover bolts is analyzed in detail. The results demonstrate that pressure loads on head-cover bolts change dramatically during the load rejection process. The flow-induced deformation of the inner head-cover during the load rejection is larger than that of other structures, and the flow-induced displacement and stress of different head-cover bolts are not uniform. The achieved conclusions in this study can be a useful reference for the design and operation of head-cover bolts for other PT units and high-head Francis turbine units.

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Mohamed, A. "Performance comparisons of AC load-flow techniques for real time applications." IEE Proceedings C Generation, Transmission and Distribution 138, no. 5 (1991): 457. http://dx.doi.org/10.1049/ip-c.1991.0058.

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Zhu, AiHua, Caozheng Fu, JianWei Yang, Qiang Li, Jiao Zhang, Hongxiao Li, and Kaiqi Zhang. "Research on the wheel wear of metro vehicles based on the time-varying passenger flow." Industrial Lubrication and Tribology 71, no. 9 (November 4, 2019): 1038–46. http://dx.doi.org/10.1108/ilt-01-2019-0014.

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Purpose This study aims to investigate the effect of time-varying passenger flow on the wheel wear of metro vehicles to provide a more accurate model for predicting wheel wear and a new idea for reducing wheel wear. Design/methodology/approach Sectional passage flow data were collected from an operational metro line. A wheel wear simulation based on time-varying passenger flow was performed via the SIMPACK software to obtain the worn wheel profile and wear distribution. The simulation involves the following models: vehicle system dynamics model, wheel-track rolling contact model, wheel wear model and variable load application model. Later, the simulation results were compared with those obtained under the traditional constant load condition and the measured wear data. Findings For different distances traveled by the metro vehicle, the simulated wheel profile and wear distribution under the variable load remained closer to the measurements than those obtained under the constant load. As the distance traveled increased, the depth and position of maximum wear and wear growth rate under the variable load tended to approach the corresponding measured values. In contrast, the simulation results under the constant load differed greatly from the measured values. This suggests that the model accuracy under the variable load was significantly improved and the simulation results can offer a more accurate basis for wear prediction. Practical implications These results will help to predict wheel wear more accurately and provide a new idea for simulating wheel wear of metro vehicles. At the same time, measures for reducing wheel wear were discussed from the perspective of passenger flow changes. Originality/value Existing research on the wheel wear of metro vehicles is mainly based on the constant load condition, which is quite different from the variable load condition where the passenger flow in real vehicles varies over time. A method of simulating wheel wear based on time-varying load is proposed in this paper. The proposed method shows a great improvement in simulation accuracy compared to traditional methods and can provide a more accurate basis for wear prediction and wheel repair.

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Shubaili, Mohammed, Ali Elawadi, Sarah Orton, and Ying Tian. "Time-Dependent Behavior of Reinforced Concrete Beams under High Sustained Loads." Applied Sciences 12, no. 8 (April 15, 2022): 4015. http://dx.doi.org/10.3390/app12084015.

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High levels of sustained load can lead to time-dependent failure of reinforced concrete (RC) members. This in turn may lead to collapse of all or part of a building. Design errors, construction errors, and material deterioration may lead to concrete elements being subjected to high levels of sustained loads well exceeding typical service loads. Plain concrete can experience compressive failure when subjected to a high sustained stress (over 75% of its short-term strength). However, there is a lack of knowledge about the time-dependent strength and stiffness characteristics of RC members under high sustained loads. This paper presents the results of experimental testing of simply supported shear-controlled RC beams under high sustained loads. Two series of beams, consisting of 4 and 5 beams, were tested at concrete ages of 67 to 543 days to represent in-service concrete structures. The applied sustained loads ranged from 82% to 98% of the short-term capacity and lasted for 24 to 52 days. Test results indicated that high sustained load may eventually lead to failure (collapse); however, the level of load needs to be very close (~98%) to the short-term capacity. Under sustained load, all specimens experienced increased deflection with over half of the deflection increase occurring in the first 24 h. The sustained load increased the deflection at shear failure by 190% on average. The increase in the beam deflection may allow for load redistribution in redundant structural systems. A sharp increase in deflection due to tertiary creep occurred in a short time (~2 min) before failure, indicating little warning of the impending failure.

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Ketabi, Shiva, Matthew Buckley, Parsa Pazhooheshy, Faraz Farahvash, and Yashar Ganjali. "Correlation-Aware Flow Consolidation for Load Balancing and Beyond." ACM SIGMETRICS Performance Evaluation Review 49, no. 4 (June 2, 2022): 105–10. http://dx.doi.org/10.1145/3543146.3543170.

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Existing load balancing solutions rely on direct or indirect measurement of rates (or congestion) averaged over short periods of time. Sudden fluctuations in flow rates can lead to significant undershooting/ overshooting of target link loads. In this paper, we make the case for taking variations and correlations of flows into account in load balancing. We propose correlation-aware flow consolidation, i.e. aggregating inversely correlated (or uncorrelated) flows into superflows and using them as building blocks for load balancing. Superflows are smoother than individual flows, and thus are easier to estimate with a higher confidence, and can reduce overshooting/ undershooting of link capacities. We present heuristic methods combined with predictive models to consolidate flows and show they can lead to significant reductions in rate standard deviations compared to correlation-agnostic solutions (up to 33% and 12% improvements at the 50th and 99th percentiles respectively for 20 superflows based on real traffic traces).

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Hiwarkar, Dr Chandrashekhar S., Abhay M. Halmare, Anurag A. Belsare, Nitin B. Mohriya, and Roshan Milmile. "Load Flow Analysis on IEEE 14 Bus System." International Journal for Research in Applied Science and Engineering Technology 10, no. 4 (April 30, 2022): 1572–74. http://dx.doi.org/10.22214/ijraset.2022.41590.

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Abstract: This article presents a load flow analysis of an IEEE14 BUS system using the Newton-Raphson method, which simplifies the analysis of load balancing problems. The software used for the programming platform is MATLAB. This paper gives an overview of the electrical performance and power flows (real and reactive) under a steady state. There are various methods for load flow computations. The gauss-seidel method is more popular in smaller systems because of less computational time. In the case of larger systems computation time increases in this condition, the Newton-Raphson method is preferred. This project aims to develop a MATLAB program to calculate voltages and active and reactive power at each bus for IEEE 14 bus systems. The MATLAB program is executed with the input data and results are compared. Keywords: load flow studies, Newton-Raphson method, IEEE 14 bus system.

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Ahmad, Najeeb, Muhammad Nufail Farooqi, and Didem Unat. "Load Balancing for Parallel Multiphase Flow Simulation." Scientific Programming 2018 (2018): 1–14. http://dx.doi.org/10.1155/2018/6387049.

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This paper presents a scalable dynamic load balancing scheme for a parallel front-tracking method based multiphase flow simulation. In this simulation employing both Lagrangian and Eulerian grids, processes operating on Lagrangian grid are susceptible to load imbalance due to moving Lagrangian grid points (bubbles) and load distribution based on spatial location of bubbles. To load balance these processes, we distribute load keeping in view both current processor load distribution and bubble spatial locality and remap interprocess communication. The result is a uniform processor load distribution and predictable and less expensive communication scheme. Scalability studies on the Hazel Hen supercomputer demonstrate excellent scaling with exponential savings in execution time as the problem size becomes increasingly large. While moderate speedup is observed for strong scaling, speedup of up to 30% is achieved over nonload-balanced version when simulating 13824 bubbles on 4096 cores for weak scaling studies.

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Satyavir, Singh. "Power flow control capability analysis of unified power flow controller." i-manager's Journal on Power Systems Engineering 10, no. 2 (2022): 12. http://dx.doi.org/10.26634/jps.10.2.18808.

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In the field of power system restructuring, Flexible Alternating Current Transmission System (FACTS) technology has become indispensable for alleviating the challenges of load flow control, voltage control, transient stability, and dynamic stability. The Unified Power Flow Controller (UPFC) is the fastest, most flexible, and most capable FACTS device because it has the full advantage of providing simultaneous and independent real-time control of voltage, impedance, and phase angle, which are the main power system parameters that affect system performance. This paper uses a Newton-Raphson load flow that includes UPFC to analyze how UPFC can control the flow of power.

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Li, Hongqiu, Jinhui Jiang, Wenxu Cui, Jiamin Zhao, and M. Shadi Mohamed. "One Novel Dynamic-Load Time-Domain-Identification Method Based on Function Principle." Applied Sciences 12, no. 19 (September 25, 2022): 9623. http://dx.doi.org/10.3390/app12199623.

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In order to ensure the reliability of the structural design, it is necessary to know the external loads acting on the structure. In this paper, we propose a novel method to identify the dynamic loads based on function principles in the time domain. Assuming the external load remains constant within one micro segment, we establish a linear relationship between external load and structural response in the micro segments based on the mechanical energy conservation law. Next, the external load is obtained by solving the inverse problem in each micro-segment. Finally, the external load in the whole time domain is achieved by fitting the load-identification results in each micro segment. In order to verify the effectiveness and accuracy, single-force and two-force identification, and load identification with noise simulations, are performed on the structures, and the identification results are compared to the ones of the traditional time-domain method with a deviation of less than 5%. The proposed method can effectively solve the problem of cumulative errors in the time-domain method, while its resistance to noise interference is also strong. At last, we verify the experimental performance of the proposed method. The experimental results show the effectiveness and high accuracy of the proposed method. This work presents a first attempt to solve the structural dynamic load with an approach based on a function principle.

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Hu, Xiao Li, Wei Yan, Qin Xiang, and Yu Ting Xie. "Hydraulic Excavator Bucket Teeth Load-Time Courses Measurement." Advanced Materials Research 945-949 (June 2014): 2048–52. http://dx.doi.org/10.4028/www.scientific.net/amr.945-949.2048.

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Based on the bucket teeth load-time courses calculation model under bucket digging condition, the stresses on the hydraulic cylinder piston rods of boom and bucket and the real-time length of bucket hydraulic cylinder were set as measured variables, and a measuring method of the bucket teeth load-time courses was developed which had the advantages of less measuring points, simplified measurement process and low cost. The bucket teeth load-time courses were calculated by inputting the measuring data into the self-developed Constructing Hydraulic Excavators Load Spectrum software, and its characteristics of each digging step in one excavation cycle at digging macadam were analyzed. Then, using rain-flow counting module in FE-SAFE software, the statistical graphs of bucket teeth load-time courses were acquired which could provide the basis for hydraulic excavator reliability design and fatigue life prediction.

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Zhu, Linbo, Yongsheng Zhu, and Yuping Yan. "Methods to test and generate the wear load spectrum of journal bearing in concrete pump." Advances in Mechanical Engineering 13, no. 4 (April 2021): 168781402110077. http://dx.doi.org/10.1177/16878140211007716.

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Load spectrum is the basis of wear analysis and life prediction in journal bearing. This paper proposed a method to generate the wear load spectrum from the measured loads that avoiding the errors introduced by the assumptions of traditional constant load. An axle pin load sensor that can recognize the load value and its orientation is developed to test the original wear loads of journal bearing in a concrete pump under working conditions. The interactive influence of perpendicular components in the measured loads is involved by introducing two effect coefficients. Subsequently, the amplitude distribution of the wear load and its lasting time are extracted from the measured complex load-time history using the rain-flow counting method and Weibull distribution. The wear load spectrum is generated by dividing the continuous load into eight load steps. The validity of the approach is supported by finite element analysis on the wear simulation of journal bearing using the generated load spectrum and the measured load. In addition, the effects of load types and load sequence on the wear are discussed based on the proposed method and the FE model. This study provides guidelines to efficiently generate the wear load spectrum for journal bearing, and enhances its reliability of wear prediction in the experimental tests and theoretical analysis.

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Cataliotti, Antonio, Cristiano Cervellera, Valentina Cosentino, Dario Di Cara, Mauro Gaggero, Danilo Maccio, Giuseppe Marsala, Antonella Ragusa, and Giovanni Tine. "An Improved Load Flow Method for MV Networks Based on LV Load Measurements and Estimations." IEEE Transactions on Instrumentation and Measurement 68, no. 2 (February 2019): 430–38. http://dx.doi.org/10.1109/tim.2018.2847818.

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Mao, Wen Bo, Ke Wang, and Jian Tao Liu. "A Model of Continuous Optimized Power Flow with DR." Advanced Materials Research 805-806 (September 2013): 452–57. http://dx.doi.org/10.4028/www.scientific.net/amr.805-806.452.

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A model of continuous optimized power flow (COPF) is proposed, concluding demand response (DR). According to different implementation mechanisms, a series of DR models are built, such as: time of use (TOU), real time price (RTP), critical peak price (CPP), and interruptible load (IL). The influences of these kinds of DR on power system are analyzed, including peak load reduction, cost reduction, and reservation optimization. The results show that: DR can cut the cost, reduce the peak load, and promote the reservation optimization.

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Muruganantham, Balakrishnan, and Ramachandran Gnanadass. "Wind Integrated Time series load flow analysis for a Practical Distribution System." Revista Facultad de Ingeniería Universidad de Antioquia, no. 85 (December 2017): 18–32. http://dx.doi.org/10.17533/udea.redin.n85a04.

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Tari, Zahir, James Broberg, Albert Y. Zomaya, and Roberto Baldoni. "A least flow-time first load sharing approach for distributed server farm." Journal of Parallel and Distributed Computing 65, no. 7 (July 2005): 832–42. http://dx.doi.org/10.1016/j.jpdc.2005.02.007.

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Guo, Jianqiang, Huili Bi, Guohu Luo, and Zhengwei Wang. "Prediction on the axial water thrust characteristics of pump turbine runner under partial load." Journal of Physics: Conference Series 2441, no. 1 (March 1, 2023): 012044. http://dx.doi.org/10.1088/1742-6596/2441/1/012044.

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Abstract For the high head pump turbine, the unit instability during its operation mainly dues to the hydraulic vibration inside the machinery, which will cause the mechanical fatigue failure under certain circumstances. In this paper, the flow pattern and the runner axial water thrust in turbine model under partial load were analyzed by numerical simulation. The internal flow field instability and vortex load characteristics of the runner were analyzed to obtain the reasons for the different axial water thrust characteristics of the runner under two different loads. The results showed that due to the reduction of the guide vane opening, the flow rate is smaller at 50% load, and the free flow vortex structure on the high-pressure side of the runner blade inlet strengthens the impact of the water flow on the runner. Moreover, when the pressure difference between the runner blades decreases and the axial water thrust of the blades decreases, the total axial water thrust of the runner decreases and fluctuates frequently with time.

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Suresh, Vishnu Sidaarth. "Comparison of Solvers Performance for Load Flow Analysis." Transactions on Environment and Electrical Engineering 3, no. 1 (February 16, 2019): 26. http://dx.doi.org/10.22149/teee.v3i1.131.

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Load flow studies are carried out in order to find a steady state solution of a power system network. It is done to continuously monitor the system and decide upon future expansion of the system. The parameters of the system monitored are voltage magnitude, voltage angle, active and reactive power. This paper presents techniques used in order to obtain such parameters for a standard IEEE – 30 bus and IEEE-57 bus network and makes a comparison into the differences with regard to computational time and effectiveness of each solver

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Ouyang, Ying. "A Gap-Filling Tool: Predicting Daily Sediment Loads Based on Sparse Measurements." Hydrology 9, no. 10 (October 18, 2022): 181. http://dx.doi.org/10.3390/hydrology9100181.

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Sediment load in streams is known as both a carrier and a potential source of contaminants, while sediment deposition can alter stream flow, stage and morphology, and thereby has broad impacts on stream hydrology, aquatic life, and recreation activity. For vast amounts of watersheds around the world, sparse daily measured sediment data may exist, but continuous and multi-year daily measured sediment data are largely unavailable because of time-consuming and budget constraint for measurements. However, when developing total maximum daily load (TMDL) and calibrating/validating watershed models for sediments, such continuous and multi-year datasets are inevitably required. This study extended the flow-weighted method, developed by Ouyang (Ouyang, Y. Environ. Monit. Assess. 193, 422 (2021)) to predict the continuous and multi-year daily sediment loads based on sparse, limited, and discontinuous measured data. This daily sediment load gap-filling tool was validated using measured data from six different US Geological Survey (USGS) gage stations across US. Results showed that the flow-weighted method well predicted daily sediment loads when a good linear correlation existed between measured seasonal sediment loads and measured seasonal stream discharges, which is a prerequisite to apply the flow-weighted method. Five out of six selected USGS gage stations used in this study met this prerequisite. The flow-weighted method (along with an example R script for implementing the method) is a useful tool for filling the daily sediment load gaps.

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Jin, Mengren, and Qingfeng Wang. "Energy-saving control for electro-hydraulic systems under time-varying negative loads." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 232, no. 5 (March 21, 2018): 608–21. http://dx.doi.org/10.1177/0959651818758811.

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In a hydraulic system, employment of counterbalance valve introduces sizable energy consumption. In addition, a pressure-feedback control architecture with inflexible parameters causes instability under time-varying negative loads. As an alternative, an adjustable meter-out orifice was adopted, and a stable controller was proposed in this study. By combining inlet pressure and velocity, the concept of a flow rate follower was developed. Mathematical analysis of dynamic model illustrated that both the inlet pressure and velocity converged to a range related to the flow rate follower bounds. Feedback linearization with robust control was utilized such that flow rate follower converged in the presence of parametric uncertainties; meanwhile, a high-gain load observer was constructed for disturbance compensation. The effectiveness of the controller was verified by experiments and its performance discussed. As a result, the inlet pressure was held near a specified low value, thus significantly reducing energy consumption. Also, the velocity matched the supply flow rate, and the oscillations were acceptable in applications.

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Han, Jiazhen, Yudong Xie, Yong Wang, and Qixian Wang. "Dynamic Simulation of a Warship Control Valve Based on a Mechanical-Electric-Fluid Cosimulation Model." Science and Technology of Nuclear Installations 2021 (April 19, 2021): 1–14. http://dx.doi.org/10.1155/2021/6683871.

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Control valves have an important function in the warship power system. In engineering practice, the fluid oscillation inside the control valve causes the additional load to the valve actuator. When the additional load is added to the original load of the valve, it is possible that the required driving force (or driving moment) of the valve is greater than the maximum force (or moment) output by the actuator, which may cause the abnormal stop of the actuator. Conventionally, the interaction effect of the valve mechanical and electric components on the valve chamber’s flow field cannot be considered in computational fluid dynamics (CFD) simulations, so the oscillating fluid loads cannot be accurately obtained. In order to solve this problem, the mechanical-electric-fluid integrated valve model, using the FLUENT and AMESim cosimulation method, was developed to embody the interaction effect between the components of each part of the control valve and exhibit the fluid oscillation during the operating process of the control valve. Compared with the pure software simulations, the unsteady flow characteristics and dynamic response of the actuator were synchronously obtained in this study, which accurately captured the sudden fluid loads required for further compensation. At the same time, the differences in performance of different valve plugs were compared. The stability time of the valve plug and oscillation amplitude of the unstable fluid loads were distinct for control valves with different flow characteristics. The results can aid in understanding the instability mechanism of the fluid load in the control valve better, which provides the calculation basis for compensating the additional load on the valve plug and improve the reliability of the control valve.

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Rettinger, Christoph, and Ulrich Rüde. "Dynamic Load Balancing Techniques for Particulate Flow Simulations." Computation 7, no. 1 (January 23, 2019): 9. http://dx.doi.org/10.3390/computation7010009.

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Parallel multiphysics simulations often suffer from load imbalances originating from the applied coupling of algorithms with spatially and temporally varying workloads. It is, thus, desirable to minimize these imbalances to reduce the time to solution and to better utilize the available hardware resources. Taking particulate flows as an illustrating example application, we present and evaluate load balancing techniques that tackle this challenging task. This involves a load estimation step in which the currently generated workload is predicted. We describe in detail how such a workload estimator can be developed. In a second step, load distribution strategies like space-filling curves or graph partitioning are applied to dynamically distribute the load among the available processes. To compare and analyze their performance, we employ these techniques to a benchmark scenario and observe a reduction of the load imbalances by almost a factor of four. This results in a decrease of the overall runtime by 14% for space-filling curves.

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Schilperoort, R. P. S., J. Dirksen, J. G. Langeveld, and F. H. L. R. Clemens. "Assessing characteristic time and space scales of in-sewer processes by analysis of one year of continuous in-sewer monitoring data." Water Science and Technology 66, no. 8 (October 1, 2012): 1614–20. http://dx.doi.org/10.2166/wst.2012.115.

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Long-term and high-frequency in-sewer monitoring opens up a broad range of possibilities to study (influences on) water quantity and quality variations. Using data from the Eindhoven wastewater system in The Netherlands both dry weather flow and wet weather flow situations have been studied. For approximately 160 dry weather days mean diurnal variations of flow and pollutant concentrations have been derived. For wet weather situations (≈ 40 storm events) peak load factors have been studied. Generally, peak load factors for all considered pollutant parameters are larger than one. Peak load factors for particulate matter are larger than for dissolved constituents. Also, the smallest catchment area consistently shows the largest mean peak factors and vice versa.

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Horiguchi, Toshiyuki, and Yoshiharu Komatsu. "Method to evaluate the effect of inclination angle of steel open-type check dam on debris flow impact load." International Journal of Protective Structures 10, no. 1 (August 6, 2018): 95–115. http://dx.doi.org/10.1177/2041419618789702.

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Although the latest statistics indicate a decrease in the number of victims of natural disasters in Japan, the number of sediment disasters has increased. A countermeasure against natural disasters is provided by the installation of a steel open-type check dam (hereafter, open Sabo dam). The open Sabo dam is expected to capture boulders (more than 1.0 m in diameter) contained in debris flow of which boulders concentrate in front part. When a debris flow impacts an open Sabo dam, the large impact load on the steel pipes are caused by the impact of boulders under debris flow. Therefore, it is important to evaluate the impact of both boulders and the following soil and small gravels including fluid force of the open Sabo dam from the design point of view. Although an open Sabo dam has various shapes especially, the every open Sabo dams is evaluated by the same design method in Japan. It is necessary to propose the load evaluation method in the experiment scale in contrast with different shape of open Sabo dam. This article presents an experimental approach to determine the effect of the front inclination angle of steel open Sabo dams on the impact load. The debris flow impacts 1/40 scale models of steel open Sabo dams which are set in a flow channel flume, and the debris flow load is measured by using three load cells placed horizontally at the back of the Sabo dam model. Different front inclination angles are set for each Sabo dam models. The time history of the impact load is examined by comparing the loads corresponding to four kinds of dams, which are different from the front inclination angles, and decrease of impact load considering the buffering effect of driftwoods in debris flow.

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Romero, A. A., H. C. Zini, and G. Ratta. "An overview of approaches for modelling uncertainty in harmonic load-flow." Ingeniería e Investigación 31, no. 2SUP (June 1, 2011): 18–26. http://dx.doi.org/10.15446/ing.investig.v31n2sup.25207.

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Harmonic distortion is a growing problem in all power systems (PS) around the world due to the increasing use of electronic power devices and nonlinear loads (NLL). Several methods have been developed for the computational analysis of PS harmonic load-flow (HLF). These approaches allow harmonic distortion to be estimated at each PS bus when NLLs (the harmonic sources) are distributed throughout a whole network. Some widely accepted deterministic formulations are used in HLF analysis; however, harmonic distortion in PS is a time-varying phenomenon because both linear loads (LL) and NLLs change non-predictably all the time. Moreover, network configuration also varies and such considerations make HLF calculation a mathematical problem which must be able to model the uncertainty associated with input data. Some approaches based on probability theory and others using fuzzy sets and possibility theories have been proposed for modeling such uncertainty. This paper was thus aimed at providing an overview regarding these approaches. The main HLF formulations within probabilistic and possibilistic frameworks have thus been introduced and some numerical comparisons have been made to clarify some concepts raised.

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Bie, Pei, Buhan Zhang, Hang Li, Yong Wang, Le Luan, Guoyan Chen, and Guojun Lu. "Chance-Constrained Real-Time Dispatch with Renewable Uncertainty Based on Dynamic Load Flow." Energies 10, no. 12 (December 12, 2017): 2111. http://dx.doi.org/10.3390/en10122111.

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Liu, Yazhi, Jiye Zhang, Wei Li, Qianqian Wu, and Pengmiao Li. "Load Balancing Oriented Predictive Routing Algorithm for Data Center Networks." Future Internet 13, no. 2 (February 22, 2021): 54. http://dx.doi.org/10.3390/fi13020054.

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A data center undertakes increasing background services of various applications, and the data flows transmitted between the nodes in data center networks (DCNs) are consequently increased. At the same time, the traffic of each link in a DCN changes dynamically over time. Flow scheduling algorithms can improve the distribution of data flows among the network links so as to improve the balance of link loads in a DCN. However, most current load balancing works achieve flow scheduling decisions to the current links on the basis of past link flow conditions. This situation impedes the existing link scheduling methods from implementing optimal decisions for scheduling data flows among the network links in a DCN. This paper proposes a predictive link load balance routing algorithm for a DCN based on residual networks (ResNet), i.e., the link load balance route (LLBR) algorithm. The LLBR algorithm predicts the occupancy of the network links in the next duty cycle, according to the ResNet architecture, and then the optimal traffic route is selected according to the predictive network environment. The LLBR algorithm, round-robin scheduling (RRS), and weighted round-robin scheduling (WRRS) are used in the same experimental environment. Experimental results show that compared with the WRRS and RRS, the LLBR algorithm can reduce the transmission time by approximately 50%, reduce the packet loss rate from 0.05% to 0.02%, and improve the bandwidth utilization by 30%.

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Sun, Qi, Fang Sun, Cai Liang, Chao Yu, and Yamin Zhang. "Research on digital flow control model of urban rail transit under the situation of epidemic prevention and control." Smart and Resilient Transport 3, no. 1 (February 15, 2021): 78–92. http://dx.doi.org/10.1108/srt-09-2020-0010.

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Purpose Beijing rail transit can actively control the density of rail transit passenger flow, ensure travel facilities and provide a safe and comfortable riding atmosphere for rail transit passengers during the epidemic. The purpose of this paper is to efficiently monitor the flow of rail passengers, the first method is to regulate the flow of passengers by means of a coordinated connection between the stations of the railway line; the second method is to objectively distribute the inbound traffic quotas between stations to achieve the aim of accurate and reasonable control according to the actual number of people entering the station. Design/methodology/approach This paper analyzes the rules of rail transit passenger flow and updates the passenger flow prediction model in time according to the characteristics of passenger flow during the epidemic to solve the above-mentioned problems. Big data system analysis restores and refines the time and space distribution of the finely expected passenger flow and the train service plan of each route. Get information on the passenger travel chain from arriving, boarding, transferring, getting off and leaving, as well as the full load rate of each train. Findings A series of digital flow control models, based on the time and space composition of passengers on trains with congested sections, has been designed and developed to scientifically calculate the number of passengers entering the station and provide an operational basis for operating companies to accurately control flow. Originality/value This study can analyze the section where the highest full load occurs, the composition of passengers in this section and when and where passengers board the train, based on the measured train full load rate data. Then, this paper combines the full load rate control index to perform reverse deduction to calculate the inbound volume time-sharing indicators of each station and redistribute the time-sharing indicators for each station according to the actual situation of the inbound volume of each line during the epidemic. Finally, form the specified full load rate index digital time-sharing passenger flow control scheme.

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Wang, Jin, Liang Zhou, and Li Tian. "ILP-based multiperiod flow routing and scheduling method in time-sensitive network." Journal of Physics: Conference Series 2384, no. 1 (December 1, 2022): 012032. http://dx.doi.org/10.1088/1742-6596/2384/1/012032.

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Abstract Time-sensitive network (TSN) provides end-to-end data transfer with very low latency and high reliability on the basis of Ethernet. It is suitable for time-sensitive applications and will be widely used in scenarios such as autonomous driving and industrial Internet. When the existing time-sensitive flow routing and scheduling methods do not consider the shared bandwidth of the flow triggered by different cycle times, the possibility of conflict is different, which leads to the inaccuracy of the index to measure the scheduling bottleneck. This paper analyses the different cycle time-sensitive flow between the possibility of conflict, puts forward a kind of applicable to passes based on integer linear programming cycle time-sensitive traffic scheduling algorithm, according to the characteristics of the cycle time-sensitive flow carries on the preliminary classification and sorting, and developed a series of scheduling constraints, implementation is sensitive to time flow of packet scheduling. The experiment can be conducted from the three perspectives of average end-to-end delay, maximum load, and flow scheduling. The proposed routing method was compared with the existing benchmark routing algorithm evaluation. The results show that the proposed method can significantly improve the capacity of the network sensitive to time flow, reduce load scheduling by optimizing the network bottleneck at the same time, and improve the schedulability.

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Wang, Bing, Peixiu Wu, Quanchao Chen, and Shaoquan Ni. "Prediction and Analysis of Train Passenger Load Factor of High-Speed Railway Based on LightGBM Algorithm." Journal of Advanced Transportation 2021 (June 15, 2021): 1–10. http://dx.doi.org/10.1155/2021/9963394.

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In order to improve the prediction accuracy of train passenger load factor of high-speed railway and meet the demand of different levels of passenger load factor prediction and analysis, the influence factor of the train passenger load factor is analyzed in depth. Taking into account the weather factor, train attribute, and passenger flow time sequence, this paper proposed a forecasting method of train passenger load factor of high-speed railway based on LightGBM algorithm of machine learning. Considering the difference of the influence factor of the passenger load factor of a single train and group trains, a single train passenger load factor prediction model based on the weather factor and passenger flow time sequence and a group of trains’ passenger load factor prediction model based on the weather factor, the train attribute, and passenger flow time sequence factor were constructed, respectively. Taking the train passenger load factor data of high-speed railway in a certain area as an example, the feasibility and effectiveness of the proposed method were verified and compared. It is verified that LightGBM algorithm of machine learning proposed in this paper has higher prediction accuracy than the traditional models, and its scientific and accurate prediction can provide an important reference for the calculation of passenger ticket revenue, operation benefit analysis, etc.

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Nadia, Awatif, Md Sanwar Hossain, Md Mehedi Hasan, Khondoker Ziaul Islam, and Shahajan Miah. "Quantifying TRM by Modified DCQ Load Flow Method." European Journal of Electrical Engineering 23, no. 2 (April 23, 2021): 157–63. http://dx.doi.org/10.18280/ejee.230210.

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In the integrated power system network uncertainty can occur at any time. The transmission reliability (TRM) margin is the amount of transmission capacity that guarantees that the transmission network is protected from instability in the operating state of the system. The calculation of the available transfer capacity (ATC) of the transmission reliability margin should be included in a deregulated power system to ensure that the transmission network is safe within a fair range of uncertainties that arise during the power transfer. However, the TRM is conserved as a reliability margin to reflect the unpredictability of the operation of the electric system. Besides, the system operator (SO) utilizes the TRM value during unreliability by adjusting the ATC value some amount up or down to account for errors in data and uncertainty in the model. This paper describes a technique for TRM estimation by modified DCQ load flow method considering VAR transfer distribution factor. The main focus of this study is to get a new approach to determine TRM by incorporating with ATCQ considered reactive power and sensitivity w.r.t ATC considered voltage magnitude. This technique is applied to the IEEE 6 bus system, and results are compared with previous results for validation. The technique leads to more exact and secure estimates of transmission reliability margin.

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Dankel, SJ, MB Jessee, SL Buckner, JG Mouser, KT Mattocks, and JP Loenneke. "Are higher blood flow restriction pressures more beneficial when lower loads are used?" Physiology International 104, no. 3 (September 2017): 247–57. http://dx.doi.org/10.1556/2060.104.2017.3.2.

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The application of blood flow restriction during low-load resistance exercise has been shown to induce muscle growth with high or low restriction pressures, however, loads lower than 20% one-repetition maximum (1RM) remain unexplored. Fourteen trained individuals completed six elbow flexion protocols involving three different loads (10%, 15%, and 20% 1RM) each of which was performed with either a low (40% arterial occlusion) or high (80% arterial occlusion) pressure. Pre- and post-measurements of surface electromyography (sEMG), isometric torque, and muscle thickness were analyzed. An interaction was present for torque (p < 0.001) and muscle thickness (p < 0.001) illustrating that all increases in pressure and/or load resulted in a greater fatigue and muscle thickness. There was no interaction for sEMG (p = 0.832); however, there were main effects of condition (p = 0.002) and time (p = 0.019) illustrating greater sEMG in the 20% 1RM conditions. Higher blood flow restriction pressures may be more beneficial for muscle growth when very low loads are used.

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S., Venkatasivanagaraju, and M. Venkateswara Rao. "Real-time Forecasting of Electrical Power System Loads using Moving Average-Extreme Learning Machine (MA-ELM) Algorithm." WSEAS TRANSACTIONS ON SYSTEMS AND CONTROL 17 (May 12, 2022): 222–33. http://dx.doi.org/10.37394/23203.2022.17.26.

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Load Forecasts are the primary factors which considered by electricity utility companies while planning power generation, power infrastructural development and load flows etc. Different forecasting techniques have been proposed from statistical to artificial intelligence-based models and the area of research is still growing. In our research work, considering the real time data of 33KV bus system which is having 34 buses and 54 lines. In this case, forecast the day ahead scheduling of various parameters such as load real power (Pload), voltage magnitude at each bus, apparent power flow between buses and total transmission losses for hourly basis and also forecasted the mentioned parameters for 5 days. The actual real time values are compared with forecasted values using two existing methods namely Extreme Learning Machine (ELM), moving average and proposed Moving Average–Extreme Learning Machine (MA-ELM) algorithm. In addition to this, forecasted the loads and losses for short term and long-term forecasting cases and verified through MATLAB programming.

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Ye, Xi, Gan Li, Tong Zhu, Lei Zhang, Yanfeng Wang, Xiang Wang, and Hua Zhong. "A Dispatching Method for Large-Scale Interruptible Load and Electric Vehicle Clusters to Alleviate Overload of Interface Power Flow." Sustainability 15, no. 16 (August 16, 2023): 12452. http://dx.doi.org/10.3390/su151612452.

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The study of dispatching methods for large-scale interruptible loads and electric vehicle clusters is of great significance as an optional method to alleviate the problem of overload in interface power flow. In this paper, the distribution model and transfer capacity of large-scale interruptible load and electric vehicle in two dimensions of time and space were firstly introduced. Then, a large-scale interruptible load and electric vehicle dispatching model considering transmission interface power flow balance was established. Finally, a case study was carried out with the city power grid as the research object. Studies show that by dispatching large-scale interruptible load and electric vehicle, the overload rate of interface power flow can be reduced by 12–17%, while the proportion of clean energy generation increased by 4.19%. Large-scale interruptible load and electric vehicles are quite different in terms of the role they play in grid regulation. The regulation cost of electric vehicles is higher than that of large-scale interruptible load, but it also has the advantages of promoting the consumption of clean energy and improving the overall operating economy. Which type of resource should be given priority is based on the actual state of the grid. In addition, the cost of electricity has a significant impact on the load response behavior of electric vehicles. It should be determined according to various factors, such as interface power flow control requirements, regulation costs, and power grid operation costs.

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Shao, Bilin, Dan Song, Genqing Bian, and Yu Zhao. "Network-Aware Data Placement Strategy in Storage Cluster System." Mathematical Problems in Engineering 2020 (April 21, 2020): 1–16. http://dx.doi.org/10.1155/2020/5970583.

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The dramatic increase of storage devices in distributed storage cluster system and the inherent characteristics of distributed deployment mode make network resources become one of the bottlenecks of data storage process. By analyzing the functional characteristics of data flow transmission of the components of the storage system, the network topology structure of the storage system is constructed, and the evaluation index of node flow load is put forward based on the degree centrality and the betweenness centrality theory of the network to explore the network topology and real-time flow characteristics. According to the evaluation index of node flow load, a network-aware data layout scheme is proposed. By balancing the flow load of bottleneck link, congestion and transmission delay can be reduced to further shorten the total task execution time and improve the efficiency of data writing.

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A. Sheela, Mrs, and Mrs J. Ranjani. "An approach for dynamically load balanced flow scheduling(DLBS) in cloud." International Journal of Engineering & Technology 7, no. 3.3 (June 8, 2018): 600. http://dx.doi.org/10.14419/ijet.v7i2.33.14844.

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The Paper based on load balanced flow scheduling algorithm. This algorithm is used in which huge amount of data send to multiple servers frequently without a few traffic, isolation in open flow network. In existing load balanced algorithm based on huge amount of data send to several server but it suffers from that that algorithm is not support to other open flow networks model and transmission pattern. In this proposed load balanced scheduled algorithm with Round Robin deals with maximizing the network throughput dynamically. The (Dynamically Load Balanced Flow Scheduling) DLBS problem is formulated , considerably a efficient heuristic scheduling algorithms was developed for the two typical Open Flow network model, they have data flow from time slot. The outcome represents load-balanced scheduling algorithms Round Robin and LOBUS with effective improvement in DLBS move toward will carry to the data centers. Plenty of researchers pay large number of attention on software-deﬁned networking.

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Yaseen, Ahmed Y., and Afaneen A. Abbood. "Study of Power System Load Flow Using FPGA and LabVIEW." Engineering and Technology Journal 38, no. 5A (May 25, 2020): 690–97. http://dx.doi.org/10.30684/etj.v38i5a.346.

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The capability to rapidly execute the power flow (PF) calculations permit engineers in assured with stay bigger assured within the dependability, protection, and economical operation of their system within the case of planned or unplanned instrumentality failures. The purpose of this work is to investigate the use of FPGA characteristics to speed up power flow computing time for the on-line monitoring system of a power system. The work comprises which is the development of the Power flow program using the Fast-decoupled method based on FPGA (Field Programmable Gate Array), and LABVIEW (graphical programming environment). The program delivered very satisfactory results to solve a 30-bus test system. These findings suggest that in general that differences between the proposed work and the conventional fast decoupled method are satisfactory. As for the execution time, because the FPGA uses parallel solutions, the performance of the proposed method is faster. Also, the engagement of the FPGA and the LabVIEW program presented an effective monitoring system for observing the power system.

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Romero-Quete, Andrés Arturo, Gastón Orlando Suvire, Humberto Cassiano Zini, and Giuseppe Rattá. "Time-varying harmonic analysis in electric power systems with wind farms, through the possibility theory." DYNA 82, no. 192 (August 25, 2015): 185–94. http://dx.doi.org/10.15446/dyna.v82n192.48617.

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<p>This paper focuses on the analysis of the connection of wind farms to the electric power system and their impact on the harmonic load-flow. A possibilistic harmonic load-flow methodology, previously developed by the authors, allows for modeling uncertainties related to linear and nonlinear load variations. On the other hand, it is well known that some types of wind turbines also produce harmonics, in fact, time-varying harmonics. The purpose of this paper is to present an improvement of the former method, in order to include the uncertainties due to the wind speed variations as an input related with power generated by the turbines. Simulations to test the proposal are performed in the IEEE 14-bus standard test system for harmonic analysis, but replacing the generator, at bus two, by a wind farm composed by ten FPC type wind turbines.</p>

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Lifits, S. A., S. I. Anisimov, and J. Meyer-ter-Vehn. "Shock Waves produced by Impulsive Load: Equation of State Effects." Zeitschrift für Naturforschung A 47, no. 3 (March 1, 1992): 453–59. http://dx.doi.org/10.1515/zna-1992-0301.

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Abstract A numerical study of the flow after impulsive load of a plane material surface is carried out. It is shown that the flow is asymptotically self-similar provided one can neglect the cold components in the equation of state. In this case the effective exponent s(t) = d l n (X s) / d ln(t), derived from the shock trajectory Xs (t) does not depend on the initial pressure pulse and approaches the exponent α of the self-similar problem for time t →∞. For equations of state containing a cold pressure term, s (t) is larger than α and changes non-monotonically with time. Some features of the flow related to the presence of cold components in pressure and internal energy are discussed.

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Zhao, Fu Qing, and Ning Li. "Flow Time and Tardiness Based on New Scheduling Rules for Dynamic Shop Scheduling with Machine Breakdown." Applied Mechanics and Materials 556-562 (May 2014): 4412–16. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.4412.

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In this paper, a comparative study on the performance of scheduling rules in job shop. Four new dispatching rules are proposed. mean, maximum ,variance of tardiness and proportion of tardy jobs have been used to evaluate the performance of various scheduling rules. Breakdown level, shop load level was considered in the comparative study. The simulation result indicate the performance of dispatching rules is being influenced by Breakdown level, shop load level.

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Chou, C. L., and D. J. Marsh. "Time course of proximal tubule response to acute arterial hypertension in the rat." American Journal of Physiology-Renal Physiology 254, no. 4 (April 1, 1988): F601—F607. http://dx.doi.org/10.1152/ajprenal.1988.254.4.f601.

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Acute hypertension was previously shown to cause partial inhibition of proximal tubule fluid reabsorption in perfused tubules in the rat. If the inhibition also occurs in unobstructed tubules receiving native glomerular filtrate, hypertension should increase end proximal flow rate despite autoregulation of glomerular filtration rate (GFR). We tested this prediction with a videodensitometric method recently developed for measurement of tubular flow rate that does not interrupt flow to the macula densa. Hypertension was induced by increasing total peripheral resistance in rats receiving several hormones at rates designed to maintain high levels of these agents. End proximal flow rate was increased 18% as early as 1.5–2 min following the induction of hypertension and increased over the course of the next 25–30 min to reach values 50% greater than controls as the hypertension was sustained. Whole-kidney GFR and renal blood flow were fully autoregulated. The results confirm that hypertension increases the fluid load to the loop of Henle, and are consistent with an effect on proximal tubule fluid reabsorption. This increase in fluid load could signal the macula densa and contribute to the efficacy of autoregulation; it could also provide a significant fraction of the increased fluid and salt excretion of pressure natriuresis.

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Journal articles on the topic 'Load and flow time'

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