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Taher, Menna, Mohamed Abaza, Mostafa Fedawy, and Moustafa Aly. "Relay Selection Schemes for FSO Communications over Turbulent Channels." Applied Sciences 9, no. 7 (2019): 1281. http://dx.doi.org/10.3390/app9071281.
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Free Space Optics (FSO) Communication has attracted the attention of the researchers in the last decade due to its high data rate, security, and low cost. Relay-assisted techniques are used to divide the distance to shorter hops in order to mitigate the effects of turbulence, weather attenuation, pointing error, and geometric loss. Choosing an active relay per time slot has been proven to enhance the performance of the system and decrease the loading effect on the system when compared to all active relays. This paper investigates the best relay that can be selected according to the source to relay (S-R) channel coefficient, relay to destination (R-D) channel coefficient, and source to destination (S-D) channel coefficient. A comprehensive comparison is applied to the three following cases: (a) Broadcast phase from source to relay to select the best (Proactive-Relay); (b) Broadcast phase from relay to destination after broadcasting to all relays then select (Reactive-relays); and, (c) Direct link from source-to-best relay-to-destination to conclude which method is better for different scenarios, such as turbulence regime, number of relays, different pointing error effect, and severity of S-R as compared to R-D and vice versa. The selection methods regard to four aspects: (1) Number of relays (two or three relays); (2) Distance between Source-Relay and Relay-Destination (D = 400–600 m, 500–500 m, and 600–400 m); (3) The different turbulence of Log-normal channel and Gamma-Gamma channel (with a refractive index coefficient( C n 2 = 0.5 × 10−14, 2 × 10−14 and 5 × 10−14)); and finally, (4) Beam waist ω z (pointing error).
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Aftab, Muhmmad Waleed, Sajjad Hussain, Aftab Husain, Umar Ali Khan, and Hamza Kundi. "A Deep Reinforcement-Learning-Based Relay Selection for Underwater Sensors Network." Journal of Smart Internet of Things 1, no. 1 (2023): 5–13. http://dx.doi.org/10.2478/jsiot-2023-0001.
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Abstract Due to their limited frequency range and fast fading channels, underwater sensor networks (USNs) are vulnerable to collisions of packets. In this paper, we propose a deep reinforcement learning-based relay selection scheme with shortest latency (DRL-SL) for USNs that enables to choose the relay based on the state that comprised of the bit error rate (BER) of the previous transmission, and the jamming power measured by the relay node. The DRL-SL-based relay selection scheme completed in two phases. In the first phase, a deep neural network based learning is performed and second phase is the real-time interaction with the underwater sensor network. Numerical results give the bound on how efficiently the system performs in terms of bit error rate, energy use, and node utility. According to the numerical results, the proposed DRL-SL based relay selection scheme can enhance relay performance in comparison to the benchmark underwater relay techniques.
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Qiu, Xiao, Blanca De la Fuente, Alberto Lorenzo, and Santiago Veiga. "Comparison of Starts and Turns between Individual and Relay Swimming Races." International Journal of Environmental Research and Public Health 18, no. 9 (2021): 4740. http://dx.doi.org/10.3390/ijerph18094740.
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The present study investigated swimmers’ performances on the starting and turning segments between individual and relay races. A total number of 72 race performances of the same swimmers in both relay 4 × 100 m finals (freestyle, medley, and mixed freestyle) and individual 100 m finals or semi-finals (butterfly, breaststroke, and freestyle) from the LEN European Swimming Championships were compared with repeated measures MANOVA. Swimmers performed 5–7% faster starts in the relay than in the corresponding individual events, despite no differences in the flight phase and a lower performance (shorter distances and slower velocities) on the underwater start section. The 15 m turn times were slower in the butterfly relay races although no specific differences in the underwater parameters were observed. These results suggest that specific training of the starting and turning segments should be performed under relay conditions to optimise pacing and performance in the underwater sections.
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González-Cueto, José Antonio, Zaid García Sánchez, Gustavo Crespo Sánchez, Hernan Hernandez, Jorge Iván Silva Ortega, and Vicente Leonel Martínez Díaz. "A mho type phase comparator relay guideline using phase comparison technique for a power system." International Journal of Electrical and Computer Engineering (IJECE) 11, no. 2 (2021): 929. http://dx.doi.org/10.11591/ijece.v11i2.pp929-944.
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This paper presents a mho distance relay simulation based on the phase comparison technique using a typical electrical power systems analysis software for two cases: when the operation state is close to the static voltage limit and during a dynamic perturbation in the system. The paper evaluates the impedance variations caused by complex voltage values, the mho polarization, and the comparator operating region into the complex plane. In addition, the paper found the information for the dynamic perturbations from the outputs considering a mid-term stability program. The simulation of the mho-phase comparator in the static voltage proximity limit detects unit distance elements with impedance measured close to reach the threshold in the steady-state. Dynamic mho simulations in the complex plane are successfully tested by plotting time phase difference curves on the comparator input signals. Relay programmers can use these curves to analyze other phase comparators applications and the corresponding models in the complex plane.
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José, Antonio González-Cueto Cruz, García Sánchez Zaid, Crespo Sánchez Gustavo, Hernández Herrera Hernán, Iván Silva-Ortega Jorge, and Leonel Martínez Díaz Vicente. "A mho type phase comparator relay guideline using phase comparison technique for a power system." International Journal of Electrical and Computer Engineering (IJECE) 11, no. 2 (2021): 929–44. https://doi.org/10.11591/ijece.v11i2.pp929-944.
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This paper presents a mho distance relay simulation based on the phase comparison technique using a typical electrical power systems analysis software for two cases: when the operation state is close to the static voltage limit and during a dynamic perturbation in the system. The paper evaluates the impedance variations caused by complex voltage values, the mho polarization, and the comparator operating region into the complex plane. In addition, the paper found the information for the dynamic perturbations from the outputs considering a mid-term stability program. The simulation of the mho-phase comparator in the static voltage proximity limit detects unit distance elements with impedance measured close to reach the threshold in the steady-state. Dynamic mho simulations in the complex plane are successfully tested by plotting time phase difference curves on the comparator input signals. Relay programmers can use these curves to analyze other phase comparators applications and the corresponding models in the complex plane.
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Lopes, Pablo Rodrigues, and Rui Bertho Junior. "Development of a Low-Cost Relay Prototype for Real-Time Power Protection Functions." Learning and Nonlinear Models 21, no. 1 (2023): 90–109. http://dx.doi.org/10.21528/lnlm-vol21-no1-art7.
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This paper presents a Raspberry Pi 3B+ based low-cost universal relay able to run power protection functions in real-time. The configurations necessary for this single-board computer to be able to provide real-time response are shown, as for latency tests to verify its response time. An experimental circuit was built to send three-phase fault signals from a Relay tester to the low-cost relay, in order to evaluate its response time to clear faults in comparison to a commercial relay. A neural networks algorithm was developed and executed in real-time by the proposed low-cost relay, which is able to differentiate three-phase faults from transient signals created from large load variations. The results show that the low-cost relay is capable of running simple and complex protection functions within a pre-defined runtime and acceptable precision, compared to a commercial protection relay. However, the sampling frequency the low-cost relay is able to handle is limited. The results have also shown that the low-cost relay meet the requirements for a soft real-time system, which is not ideal for practical power protection systems that require hard real-time systems.
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Zubić, Siniša J., and Milenko B. Djurić. "A distance relay algorithm based on the phase comparison principle." Electric Power Systems Research 92 (November 2012): 20–28. http://dx.doi.org/10.1016/j.epsr.2012.05.017.
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Zhu, Yifan, Tao Zheng, Minghao Wang, Hongcheng Zhao, and Xingguo Wang. "An Improved Directional Relay Adapted to a Distribution Network with IIG Integration." Energies 12, no. 17 (2019): 3345. http://dx.doi.org/10.3390/en12173345.
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The integration of distributed generation (DG) into a distribution network changes the network’s topology. Three-stage current protection for a radial distribution network cannot meet the requirements of relay protection for a distribution network with DG. A directional relay that is based on the positive sequence fault component (PSFC) can effectively identify faults in the positive and negative directions and can be used to solve the adaptability problem with three-stage current protection in a multi-source distribution network. However, DG and the traditional generators have different fault characteristics and are affected by different control strategies, which may lower the sensitivity of a directional relay based on the PSFC or even cause mal-operation. Focusing on this problem, this paper proposes an improved directional relay that is adapted to a distribution network with inverter-interfaced generation (IIG) integration. The improved scheme divides the operation zone of the directional relay based on the PSFC into sensitive and insensitive areas. If the result of a phase comparison is located in the insensitive area, further identification is needed according to a comparison of the current amplitudes. Simulation experiments are carried out based on PSCAD/EMTDC, and their results verify the correctness of the proposed scheme.
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Mohammed, Ali Abdulwahhab, Li Yu, Manar Al-Kali, and Desheng Wang. "Analysis of Amplify-and-Forward Cooperative Networks with Nakagami-m fading Channels For MRC Diversity Combining." TELKOMNIKA Indonesian Journal of Electrical Engineering 16, no. 3 (2015): 546. http://dx.doi.org/10.11591/tijee.v16i3.1646.
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In this paper we study the effect of diversity combining for Nakagami -m fading Channels in the amplify-and-forward cooperative networks.We derive the cumulative density function (CDF), probability density function (PDF) and moment generating function (MGF) for the multiple relay amplify-and-forward network with single half duplex channel maximal ratio combiner (MRC). In this network we investigate the cases of MRC at the destination, as well derive the exact Symbol Error Rate (SER) of M-ary phase-shift keying (M-PSK), and quadrature amplitude modulation (M-QAM) in Nakagami -m fading environment. We present a comparison between M-PSK and M-QAM modulation schemes in some representative scenarios where an arbitrary number of cooperative relays is considered.
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Kolesnikov, Evgeniy, Aleksandr Novozhilov, Dilara Rakhimberdinova, Aleksandr Kislov, and Timofey Novozhilov. "Mathematical Model of a Nonlinear Power Transformer for Needs of Relay Protection." Energies 17, no. 7 (2024): 1710. http://dx.doi.org/10.3390/en17071710.
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In this work, a mathematical model of a three-phase nonlinear transformer is suggested. The model enables simulating the transformer operation with allowance for its nonlinearity and covers needs of the relay protection. Our model has been developed on the basis of a mathematical model with phase coordinates, where differential equations are composed by the Kirchhoff’s phase-voltage law. Based on this model, we first compose a mathematical model for simulating steady-state operation modes of a transformer, taking into account the asymmetry and nonlinearity of its ferromagnetic core. In this model, the initial values of inductances and mutual inductances of loops are determined from the main phase inductance calculated by the experimentally found no-load current, and their current values are determined from the currents in windings and the magnetic fluxes in legs of the transformer core. The magnetic fluxes are calculated by the nodal-pair method. This improved mathematical model is verified through a comparison between the calculated harmonic components of the phase currents and the experimental results. The harmonic components are calculated with the use of Fourier expansion of the calculated phase currents. Their experimental values are determined with a spectrum analyzer. The calculated and experimental harmonic components of the currents of phase A during no-load and rated-load operation of the transformer are tabulated. The comparison of these results shows that the mathematical model of a three-phase transformer we suggest makes it possible to simulate currents in transformer windings under steady-state operation modes with accuracy acceptable for relay protection.
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Smith, Gregory D., Charles L. Cox, S. Murray Sherman, and John Rinzel. "Fourier Analysis of Sinusoidally Driven Thalamocortical Relay Neurons and a Minimal Integrate-and-Fire-or-Burst Model." Journal of Neurophysiology 83, no. 1 (2000): 588–610. http://dx.doi.org/10.1152/jn.2000.83.1.588.
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We performed intracellular recordings of relay neurons from the lateral geniculate nucleus of a cat thalamic slice preparation. We measured responses during both tonic and burst firing modes to sinusoidal current injection and performed Fourier analysis on these responses. For comparison, we constructed a minimal “integrate-and-fire-or-burst” (IFB) neuron model that reproduces salient features of the relay cell responses. The IFB model is constrained to quantitatively fit our Fourier analysis of experimental relay neuron responses, including: the temporal tuning of the response in both tonic and burst modes, including a finding of low-pass and sometimes broadband behavior of tonic firing and band-pass characteristics during bursting, and the generally greater linearity of tonic compared with burst responses at low frequencies. In tonic mode, both experimental and theoretical responses display a frequency-dependent transition from massively superharmonic spiking to phase-locked superharmonic spiking near 3 Hz, followed by phase-locked subharmonic spiking at higher frequencies. Subharmonic and superharmonic burst responses also were observed experimentally. Characterizing the response properties of the “tuned” IFB model leads to insights regarding the observed stimulus dependence of burst versus tonic response mode in relay neurons. Furthermore the simplicity of the IFB model makes it a candidate for large scale network simulations of thalamic functioning.
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Shumikhin, Andrey Yu, Roman V. Kirillov, and Regina T. Khazieva. "COMPUTER SIMULATION OF OPERATION OF SUBSTATION RELAY PROTECTION IN MATLAB SIMULINK PACKAGE." Electrical and data processing facilities and systems 20, no. 3 (2024): 67–79. http://dx.doi.org/10.17122/1999-5458-2024-20-3-67-79.
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Relevance Modern electric power systems require reliable and high-speed relay protection, which is necessary to prevent accidents and ensure stable operation of the power system. With the development of computer technology, it becomes possible to use modern software tools for modeling and analyzing the operation of relay protection. Matlab Simulink provides the necessary toolset that allows you to accurately simulate various types of relay protection and their interaction with other network components. Aim of research This article simulates the relay protection of a substation in order to further apply its results in the study of relay protection and automation of electric power systems, principles of operation and devices of relay protection of lines and other electrical installations. Research methods The essence of this work is to develop computer models of relay protection of substations based on Matlab/Simulink software. The models are tailored to the characteristics of certain electrical installations and include components that serve as power sources, switching elements, logic, control, measurement and comparison, the coordinated operation of which allows to achieve high selectivity, reliability and performance of relay protection. Results The results of the research conducted by the authors are aimed at obtaining functioning computer models of relay protection of electric grid facilities, which can be used to teach students how to model electrical installations, as well as analyze the processes occurring in electric networks in the event of accidents and abnormal modes. The simulation results obtained during the work are presented as graphs of three-phase voltages and currents that occur during short circuits in electrical installations.
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Feofilov, S. V., and A. V. Kozyr. "Stability of Periodic Motions and Synthesis of Relay Sampled Data Control Systems." Mekhatronika, Avtomatizatsiya, Upravlenie 20, no. 11 (2019): 655–62. http://dx.doi.org/10.17587/mau.20.655-662.
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This article is devoted to research and design of relay systems with control of data sampling. It is shown that the time sample has a significant effect on the parameters of periodic oscillations. We propose an exact method for analyzing periodic modes in digital self-oscillatory control systems with a two-position relay element and a linear piecewise-linear part is proposed. The proposed approach extends the phase hodograph method to the class of systems operating in discrete time. Two approaches have been developed to assess the stability of periodic motions in such systems. In the first approach, a discrete representation of a plant is considered and areas of stability are defined for each possible limit cycle. The sampling of the control system causes a delay in the switching of the relay in a batch mode in comparison with the continuous case. The second approach assumes the replacement of a discrete system by an equivalent continuous system with a time delay. Further, the asymptotic orbital stability of self-oscillations in a relay control system (RCS) with a delay is estimated. We consider the linearization of relay systems with digital control of the input signal. It is also shown that when linearizing a relay element in a digital RCS using a useful signal, the relay transfer ratio will belong to a certain range of values. Synthesis of corrective devices for relay control systems with regard to digital implementation has been reviewed. At the stage of optimization of parameters of the relay control system, the sample is taken into account. The model example demonstrates an advantage in the synthesis of digital technologies. It is shown that when optimizing the controller parameters with regard to time discretization, it was possible to provide the desired frequency of self-oscillations, which ensures the best accuracy of the tracking mode.
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Wang, Hao, Qi Yang, Xiaopeng Li, and Wenyue Zhou. "A Method of Discriminating Between Power Swings and Faults Based on Principal Component Analysis." Applied Sciences 15, no. 5 (2025): 2867. https://doi.org/10.3390/app15052867.
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Distance protection is widely applied in AC transmission systems. It may operate incorrectly under power swings, so a power swing blocking unit (PSBU) is needed to work with the distance protection relay. Such a unit should not only block the protection relay in time when a power swing occurs, but also deblock the protection relay after detecting a fault during the power swing. In this paper, a method that satisfies these requirements is proposed. To discriminate between power swings and faults, the characteristics of three-phase voltage under a power swing and fault situation are used. Principal Component Analysis (PCA) is applied to extract and quantify the characteristics. To detect faults during power swings, an index is proposed, and the change rate of the index is used to form the criterion. Simulations for different kinds of power swing and fault situations are conducted based on a two-end system and a nine-bus system in PSCAD/EMTDC. The simulation test results indicate that the proposed method can block the protection relay reliably under a power swing and deblock the relay quickly after detecting a fault during the power swing. Moreover, the proposed method is compared with other methods. The comparison results show that the proposed method has an advantage in terms of response speed and is less affected by measurement noise.
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Sofwan, A., A. Multi, R. Soleman, Sugianto, and A. Kusuma Septian. "Leak Current Monitoring System On The Ground Cables Medium Voltage Transformer 150/20 kV." MATEC Web of Conferences 218 (2018): 01008. http://dx.doi.org/10.1051/matecconf/201821801008.
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On January, 2017 there had been fault trip at PMT 150/20 kV transformer in Jatirangon substation. For fault detection, that rele differential phase T and REF 20 kV have worked to detect this fault. The resulted impact of this fault is Power outage in feeder a 1350 A, 35 MW and 5 Mvar. The cause of this fault is the occurrence of breakdown on ground cables 20kV T-phase-core 1. This results in a short circuit to the ground so that the differential protection relay and REF 20kV work because the relay detects a fault in the ptotection zone. The result of this research is the design of an early detection monitoring tool. This tool is used to determine the amount of leakage current on the ground cable in order to minimize the occurrence of interference that causes the occurrence of electrical power outage. The result of the leakage current monitor on the ground phase cable T obtained a current of 0.6A with temperature 35 °C. With thermal failure calculation method for leakage current obtained result of 0,56180A with temperature 35 °C. Comparison of the calculation with the measurement of leakage current on the ground cable T phase is obtained at 6.36%.
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Haddadi, Aboutaleb, Evangelos Farantatos, Ilhan Kocar, and Ulas Karaagac. "Impact of Inverter Based Resources on System Protection." Energies 14, no. 4 (2021): 1050. http://dx.doi.org/10.3390/en14041050.
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Inverter-based resources (IBRs) exhibit different short-circuit characteristics compared to traditional synchronous generators (SGs). Hence, increased uptake of IBRs in the power system is expected to impact the performance of traditional protective relay schemes—set under the assumption of a SG-dominated power system. Protection engineers need to study these challenges and develop remedial solutions ensuring the effectiveness of system protection under higher levels of IBRs. To address this need, this paper studies the impact of IBRs on a variety of protective relay schemes including line distance protection, memory-polarized zero sequence directional protective relay element, negative sequence quantities-based protection, line current differential protection, phase comparison protection, rate-of-change-of-frequency, and power swing detection. For each protection function, potential misoperation scenarios are identified, and recommendations are provided to address the misoperation issue. The objective is to provide an improved understanding of the way IBRs may negatively impact the performance of traditional protection schemes as a first step towards developing future remedial solutions ensuring effective protection under high share of IBRs.
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S., SKRYPNYK, and KOLLAROV O. "Analysis of the mode of electrical network operation at single-phase accessories of voltage 6-35 kV." Journal of Electrical and power engineering 25, no. 2 (2021): 35–40. http://dx.doi.org/10.31474/2074-2630-2021-2-35-40.
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In three-phase electrical networks during the operation of power supply systems, damage to electrical equipment and difficult modes of operation are possible. Damage associated with insulation failure, rupture of wires and cables of power lines, personnel errors when switching, lead to a short circuit between the phases or on the ground. At a short circuit in a closed circuit there is a big current, voltage drop on elements of the equipment increases that leads to the general decrease in voltage in all points of a network and disturbance of work of consumers. Complex modes of operation of electrical networks occur, as a rule, as a result of accidents or after emergency shutdowns of equipment, with subsequent overloads and voltage deviations from the nominal values. And although these modes have been considered acceptable for some time, they create the preconditions for various types of damage and disorders in the operation of power grids. To ensure normal operation of electrical networks and prevent the development of accidents, it is necessary to respond quickly to changes in the mode of operation of the electrical network, immediately separate damaged equipment from serviceable and, if necessary, turn on a backup power supply. These functions are performed by relay protection and automation devices. Principles of operation of relay protection devices. 1. Current protection. Short circuits are accompanied by a sharp increase in current that exceeds the value predetermined by the calculation, which will perform simple relay protection devices that can control the value of currents. Separate the maximum current protection, which acts to disconnect the damaged network element with a time delay and current cut-offs, which operate without a time delay. The difference between them is in the choice of how to ensure selectivity. The currents controlled by the relay protection device can be measured in phases (through current transformers), or individual components of phase currents can be measured (currents of direct, reverse and zero sequences. This method is based on the method of symmetrical components). Current types of protection are divided with control of power direction (directional) and without control (non-directional). Current protection works on the principle of operation not only in case of damage to one of the network elements, but also to adjacent ones. Therefore, current protection is referred to as protection with relative selectivity. 2. Differential protection. The basis of the principle of differential protection is the comparison of homogeneous, instantaneous values at the ends of the protected element of the network (transformer, busbar section, generator, overhead line). Usually compare currents in magnitude and phase. Differential protection by its principle works only in case of damage to the protected element of the network, so it is performed without time delay and differential protection is called protection with absolute selectivity. 3. Remote protection. In the event of short circuits in the electrical network is not only a sudden increase in current, but also a sharp decrease in voltage, ie a decrease in resistance. The advantage of relay protection devices based on this principle is that the resistance to the fault does not depend on the current and voltage, but only on their ratio. This allows protection at short-circuit currents less than the nominal for electrical equipment. Single-phase earth faults account for about 70% of all damage to electrical equipment. According to the Rules of technical operation in the event of a single-phase short circuit to "ground" in 6-35 kV electrical networks, relay protection devices must act either to turn off the equipment or to "signal". At the enterprises with special working conditions and the increased risk of damage of the equipment and defeat of people by action of an electric current protection against single-phase short circuits on the earth operates on shutdown with the minimum endurance of time. Thus, after the analysis of the modes of operation of power supply systems, the importance of using switching devices of relay protection to ensure normal operating conditions of electrical networks and prevent accidents is confirmed. Also, the use of relay protection devices must be justified for each individual electrical equipment according to the principles of operation and characteristics of the proper functioning of the switching apparatus. In case of emergencies, namely single-phase earth faults, 6-35 kV electrical network operation modes and operation of single-phase earth fault protection are performed according to various technical parameters, depending on the type and connection scheme of the neutral of this power system.
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Tseng, Kuo-Hsiung, Ching-Lin Huang, and Wei-Zhe Li. "Global Positioning System Application in Current Phase Comparison of Differential Protection Relay of Power Transmission Line." Electric Power Components and Systems 39, no. 15 (2011): 1621–31. http://dx.doi.org/10.1080/15325008.2011.608768.
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Lin, Chia-Hung, Te-Tien Ku, Chung-Sheng Li, and Chao-Shun Chen. "Optimal Phase Balancing in Electricity Distribution Feeders Using Mixed-Integer Linear Programming." Sustainability 15, no. 5 (2023): 4473. http://dx.doi.org/10.3390/su15054473.
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A mixed-integer linear programming (MILP) model that includes reductions in neutral current, feeder energy-loss cost, customer interruption cost, and labor cost is developed to derive the optimal phase-swapping strategy to enhance the phase balancing of distribution feeders. The neutral current of the distribution feeder is reduced by the phase-swapping strategy so that the tripping of the low-energy overcurrent relay can be prevented and customer-service interruption costs and the labor cost to execute the phase-swapping works can be justified by the energy-loss reduction obtained. The novelty of the study is its derivation of the phase-swapping strategy using mixed-integer linear programming to solve the problem of the unbalance of the distribution feeders. A Taipower distribution feeder is used to derive the phase-swapping strategy to demonstrate the proposed MILP model for phase balancing. The comparison of the phase currents and neutral current before phase-swapping reveals that the three-phase balance was not only significantly improved, but that the voltage unbalance was also decreased dramatically using the proposed phase-swapping strategy.
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Bhasker, Shailendra Kumar, and Manoj Tripathy. "PHASE ANGLE SHIFT AND SLOPE BASED RESTRAINT FOR INDIRECT SYMMETRICAL PHASE SHIFT TRANSFORMER PROTECTION." Journal of Engineering and Sustainable Development 28, no. 3 (2024): 316–32. http://dx.doi.org/10.31272/jeasd.28.3.2.
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This study presents a method to limit the functioning of the differential relay during the different operating conditions of an Indirect Symmetrical Phase Shift Transformer (ISPST). The proposed method depends on two thresholds; phase angle shift (PAS) between two ends of an ISPST to discriminate internal faults and inrush conditions from normal, over-excitation, and external fault conditions and slope of differential current helps to discriminate the situation of internal fault from inrush. In the first step of the algorithm, the PAS-based threshold discriminates normal, over-excitation, and external fault conditions from magnetizing inrush and internal fault conditions. In the second step, the slope-based threshold discriminates magnetizing inrush from internal fault conditions. The reliability of the proposed method has also been examined under the condition of current transformer saturation due to heavy external faults. Additionally, the comparison of the suggested and conventional methods is discussed to check the superiority of the proposed method. The proposed method eliminates the need for phase angle shift correction in the suggested method. A variety of faults in the series and excitation unit are simulated using the PSCAD/EMTDC platform to verify the approach method.
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Markovskiy, Vadim Pavlovich, Dauren Dzhambulovich Issabekov, and Viktor Yuryevich Mel’Nikov. "Relay Protection Using Inductive Coils: A Resource-Saving Approach." Electricity 5, no. 4 (2024): 1049–67. https://doi.org/10.3390/electricity5040053.
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This paper presents the development and principle of operation of resource-saving overcurrent protection, which is an alternative to traditional current protections. The experiments were used to study the electromagnetic field for the protection of electrical installations connected to the cells of complete switchgears, voltage 6–10 kV, without the use of conventional protections with metal-core current transformers. As is known, such current transformers (CTs) have significant weight and dimensional parameters and high price costs. The method of research is comparison of the developed protection with traditional current protections made using traditional measuring current transformers. The scientific novelty of this work consists of the developmental theory of the construction of protection for inductive coils based on the measurement of electromotive force values in different modes and points in the simulation of a three-phase short circuit inside the cell of the complete switchgear. The dependence of magnetic induction on the position of the inductive coil inside the cell has been found. It has been shown that the simplest formula of the Biot–Savart–Laplace law can be used to calculate them. This paper presents and describes the conducted experiments with their methodology. As a result of the industrial application of such protections, the act of implementation of the patent for the invention of an industrial enterprise is presented. The selection of settings of resource-saving protection is presented, as well as a feasibility study of the presented protection in comparison with conventional protection. This paper consists of the following sections: The Materials and Methods section describes the methodology used to achieve the purpose of the research. The Experiments section describes all the experiments conducted to achieve the purpose of the research. The Results section presents the results of the conducted experiments, an evaluation of the use of inductive coils in relay protection, an example of calculating the selection of the settings of parameters of resource-saving protection, a presentation of the patent for the invention, and a presentation of the feasibility study of the effectiveness of the considered resource-saving protection on inductive coils. The Conclusions section presents the result of this work, which is the creation of resource-saving protection on inductance coils. The References section presents a list of the sources used.
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Toader, Dumitru, Marian Greconici, Daniela Vesa, et al. "The Influence of the Characteristics of the Medium Voltage Network on the Single Line-to-Ground Fault Current in the Resistor Grounded Neutral Networks." Designs 5, no. 3 (2021): 53. http://dx.doi.org/10.3390/designs5030053.
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One important problem in the operation of medium voltage networks is the detection of a single-line-to-ground fault in its incipient state, when the fault resistance values are very high. In a medium voltage (MV) distribution network with a neutral grounding resistor (NGR), one of the methods employed to discriminate a single line-to-ground fault is the use of an overcurrent relay with an operating characteristic adjusted according to the effective value of the current flowing through the limiting resistor. In case of a single line-to-ground fault with a high fault resistance value, the correct tripping settings of the protective relay require the precise computation of this current. In comparison to the assumptions made by the models from the literature—the three-phase voltage system of the medium voltage busbars is symmetrical and there are no active power losses in the network insulation—the model proposed in this paper considers the pre-fault zero-sequence voltage of the medium voltage busbars and the active power losses in the network insulation, which is necessary in certain fault conditions where the use of the former leads to unacceptable errors.
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Ustinov, Denis A., and Abou Rashid Aysar. "Study of the protection algorithms in distributed generation systems." Proceedings of the Russian higher school Academy of sciences, no. 2 (June 28, 2023): 41–55. http://dx.doi.org/10.17212/1727-2769-2023-2-41-55.
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Current trends in the development of power supply systems for industrial facilities when applying the principles of distributed generation consist in the implementation of power supply from several power sources of different types and characteristics (photovoltaic cells, wind power plants, microturbine plants, diesel power plants), the maximum approximation of power sources to electrical loads, the use of electricity storage. The availability of such installations near consumers reduces the quantitative energy consumption by reducing the technical losses of the ge¬nerated energy and reducing dependence on fossil fuels. However, with these advantages, distri¬buted generation has created technical problems, one of which is the complication of relay protection systems due to the possibility of powering the damage point from different sides. This circumstance requires the development of new algorithms and protection schemes to ensure selectivity and to increase the sensitivity of relay protection. The purpose of the study is to analyze the algorithms of remote protection in distributed generation systems. The methods used comprise an integrated approach, including scientific analysis, processing and analysis of the results of theoretical and experimental studies in the field of relay protection of electrical complexes in networks with distributed generation. The results obtained present the analysis of various algorithms for the implementation of protection, which were implemented as proposals for distribution networks. The system of remote protection in networks containing distributed generation systems is presented, and the algorithms of operation are compared to increase the sensitivity of remote protection devices to the occurrence of various emergency modes: single-phase and three-phase short circuits. Several algorithms for increasing the sensitivity of remote protection for distribution networks in the presence of several power sources are considered. The comparison of these algorithms according to the criteria of the implementation cost, the accuracy of implementation, the number of necessary input data is also carried out. Practical significance of the research the research results can be used to take into account the effect of changes in the parameters of protected connections under conditions of electrical complexes operation in a network with distributed ge¬neration on the effectiveness of remote protection. They make it possible to increase the sensitivity and selectivity of the remote protection operation in case of emergency situations.
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Billeke, Pablo, Tomas Ossandon, Marcela Perrone-Bertolotti, et al. "Human Anterior Insula Encodes Performance Feedback and Relays Prediction Error to the Medial Prefrontal Cortex." Cerebral Cortex 30, no. 7 (2020): 4011–25. http://dx.doi.org/10.1093/cercor/bhaa017.
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Abstract Adaptive behavior requires the comparison of outcome predictions with actual outcomes (e.g., performance feedback). This process of performance monitoring is computed by a distributed brain network comprising the medial prefrontal cortex (mPFC) and the anterior insular cortex (AIC). Despite being consistently co-activated during different tasks, the precise neuronal computations of each region and their interactions remain elusive. In order to assess the neural mechanism by which the AIC processes performance feedback, we recorded AIC electrophysiological activity in humans. We found that the AIC beta oscillations amplitude is modulated by the probability of performance feedback valence (positive or negative) given the context (task and condition difficulty). Furthermore, the valence of feedback was encoded by delta waves phase-modulating the power of beta oscillations. Finally, connectivity and causal analysis showed that beta oscillations relay feedback information signals to the mPFC. These results reveal that structured oscillatory activity in the anterior insula encodes performance feedback information, thus coordinating brain circuits related to reward-based learning.
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Vikharev, D. Yu, E. A. Vorobyova, D. I. Gandzhaev, A. S. Lifshits, A. Yu Murzin, and N. A. Rodin. "Equivalence of sections of electric power systems based on operating parameters in equivalence nodes." Vestnik IGEU 1 (February 28, 2023): 25–30. http://dx.doi.org/10.17588/2072-2672.2023.1.025-030.
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When modeling steady-state and transient operating modes in electric power systems, it is necessary to determine a section of the electrical network to simplify the processes occurring in the area not covered by equivalenting. In this case, it is necessary to identify equivalents and relationships with respect to the speci-fied section. The purpose of the research is to determine the parameters of the equivalent sections of power systems and their relationships with respect to the given nodes. Methods of mathematical modeling of the elements of power systems, methods of the theory of electric circuits, and methods of matrix analysis are used. To verify the results, electrical circuits of existing power systems and the software package “Auto-mated Workplace of Relay Protection and Automation Service” have been applied. The implementation of the algorithm is carried out using programming in the Python environment. An algorithm to determine the parameters of equivalent circuits of positive, negative and zero sequences is developed and tested when solving the problem of equivalenting a network section with respect to given nodes. Comparison of the levels of currents in case of short circuits according to the developed algorithm and the software package “Automated Workplace of Relay Protection and Automation Service” in the equivalent nodes shows the high accuracy of the equivalent results in accordance with the developed algorithm. The algorithm considers transformer connections when equivalenting with respect to the nodes located at different voltage classes, as well as phase shifts caused by the star-delta conversion.
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Zitouni, M. "Improvement of power transformer differential protection through detection and exploitation of the negative sequence currents." Electrical Engineering & Electromechanics, no. 1 (February 17, 2022): 12–20. http://dx.doi.org/10.20998/2074-272x.2022.1.02.
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Introduction. Power transformers are the most important and the most expensive equipment used in transport and distribution of electrical energy. Their failure results in huge economic losses. Despite the great advances in the design of power equipment in recent years, the feeble link in the chain remains the insulation weakness of coil turns of the power transformer. The novelty of the proposed research consists in the development of a new procedure for diagnosing and localizing the occurrence of turn to turn short-circuits in the windings of three-phase power transformer. The main problems of the current differential relay are short circuits of one or more turns of a transformer winding. Hence a new approach using' the amplitude comparison between the negative sequence currents' is developed and a digital discriminator internal / external fault is applied to discriminate turn to turn faults among the other ones. The proposed procedure is based on the exploitation of the negative sequence currents. The purpose of using this new procedure is to identify small faults inside power transformer coils and to distinguish inner faults from the outer faults by using an ameliorate circuit. The method used in this paper is a novel algorithm which based on the comparison between the negative sequence current amplitudes and to calculate the corresponding phase angle shifts. The performance of the proposed procedure has been confirmed by MATLAB/Simulink environment. The results of simulation reveal the efficiency of the suggested procedure, and indicate that this procedure can provide fast and sensitive approach for detecting low level turn-to-turn faults.
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Yao, Yuanyuan, Ke Lv, Sai Huang, Xuehua Li, and Wei Xiang. "UAV Trajectory and Energy Efficiency Optimization in RIS-Assisted Multi-User Air-to-Ground Communications Networks." Drones 7, no. 4 (2023): 272. http://dx.doi.org/10.3390/drones7040272.
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An air-to-ground downlink communication network consisting of a reconfigurable intelligent surface (RIS) and unmanned aerial vehicle (UAV) is proposed. In conjunction with a resource allocation strategy, the system’s energy efficiency is improved. Specifically, the UAV equipped with a RIS starts from an initial location, and an energy-efficient unmanned aerial vehicle deployment (EEUD) algorithm is deployed to jointly optimize the UAV trajectory, RIS phase shifts, and BS transmit power, so as to obtain a quasi-optimal deployment location and hence improve the energy efficiency. First, the RIS phase shifts are optimized by using the block coordinate descent (BCD) algorithm to deal with the nonconvex inequality constraint, and then integrated with the Dinkelbach algorithm to address the resource allocation problem of the BS transmit power. Finally, for solving the UAV trajectory optimization problem, the complex objective function is transformed into a convex function, and the optimal UAV flight trajectory is obtained. Our simulation results show that the quasi-optimal deployment location obtained by the EEUD algorithm is superior to other deployment strategies in energy efficiency. Moreover, the instantaneous energy efficiency of the UAVs along the trajectory of searching the deployment location is better than other comparison trajectories. Furthermore, the RIS-assisted multi-user air-to-ground communication network can offer up to 145% improvement in energy efficiency over the traditional amplify-and-forward (AF) relay.
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M., Zitouni. "Improvement of power transformer differential protection through detection and exploitation of the negative sequence currents." Electrical Engineering & Electromechanics, no. 1 (February 17, 2022): 12–20. https://doi.org/10.20998/2074-272X.2022.1.02.
Full textAbstract:
<strong><em>Introduction. </em></strong><em>Power transformers are the most important and the most expensive equipment used in transport and distribution of electrical energy. Their failure results in huge economic losses. Despite the great advances in the design of power equipment in recent years, the feeble link in the chain remains the insulation weakness of coil turns of the power transformer. <strong>The novelty </strong>of the proposed research consists in the development of a new procedure for diagnosing and localizing the occurrence of turn to turn short-circuits in the windings of three-phase power transformer. The main problems of the current differential relay are short circuits of one or more turns of a transformer winding. Hence a new approach using' the amplitude comparison between the negative sequence currents' is developed and a digital discriminator internal / external fault is applied to discriminate turn to turn faults among the other ones. The proposed procedure is based on the exploitation of the negative sequence currents. <strong>The purpose</strong> of using this new procedure is to identify small faults inside power transformer coils and to distinguish inner faults from the outer faults by using an ameliorate circuit. <strong>The method </strong>used in this paper is a novel algorithm which based on the comparison between the negative sequence current amplitudes and to calculate the corresponding phase angle shifts. The performance of the proposed procedure has been confirmed by MATLAB/Simulink environment. The <strong>results</strong> of simulation reveal the efficiency of the suggested procedure, and indicate that this procedure can provide fast and sensitive approach for detecting low level turn-to-turn faults.</em>
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Zatsepina, V. I., E. P. Zatsepin, and P. I. Skomorokhov. "Improving the efficiency of power supply systems through the combined effect of voltage distortion." Power engineering: research, equipment, technology 21, no. 5 (2019): 79–86. http://dx.doi.org/10.30724/1998-9903-2019-21-5-79-86.
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In most cases, any abnormal mode in the distribution electrical network is eliminated by the action of relay protection and automation devices (RPA), i.e. - there is a shutdown of the damaged item. It is much more difficult to constantly maintain the normal key indicators of the quality of electrical energy in the network. With the advent of controlled voltage converters based on transistors IGCT and IGBT, static synchronous compensators STATCOM were developed. The main disadvantage of this kind of device is that the control output generated by them is static. Under conditions of increased likelihood of abnormal conditions, their dynamic compensation will be much more effective. In the process of research, the methods of dynamic continuous action of voltage on a sinusoid in a distribution electric network were used. The development of a theoretical approach was accompanied by constant monitoring of existing and developed technical solutions associated with the task set in the work. The object of the study was the distribution electrical network of industrial enterprises with a sharply alternating nature of negative network perturbations. A method has been developed for dynamic suppression of amplitude-phase voltage distortions on the basis of restoring the voltage curve due to the continuous introduction of a compensation voltage curve into the network via a booster transformer. A faster formation of the control action in comparison with analogues allows us to more effectively respond to negative network perturbations in distribution networks, especially if the nature of their occurrence changes dramatically. The proposed method is designed to maintain the quality of electricity within acceptable limits in accordance with the requirements of Russian State Standard 32144-2013.
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Rahmani, Amir Masoud, Rizwan Ali Naqvi, Efat Yousefpoor, et al. "A Q-Learning and Fuzzy Logic-Based Hierarchical Routing Scheme in the Intelligent Transportation System for Smart Cities." Mathematics 10, no. 22 (2022): 4192. http://dx.doi.org/10.3390/math10224192.
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A vehicular ad hoc network (VANET) is the major element of the intelligent transportation system (ITS). The purpose of ITS is to increase road safety and manage the movement of vehicles. ITS is known as one of the main components of smart cities. As a result, there are critical challenges such as routing in these networks. Recently, many scholars have worked on this challenge in VANET. They have used machine learning techniques to learn the routing proceeding in the networks adaptively and independently. In this paper, a Q-learning and fuzzy logic-based hierarchical routing protocol (QFHR) is proposed for VANETs. This hierarchical routing technique consists of three main phases: identifying traffic conditions, routing algorithm at the intersection level, and routing algorithm at the road level. In the first phase, each roadside unit (RSU) stores a traffic table, which includes information about the traffic conditions related to four road sections connected to the corresponding intersection. Then, RSUs use a Q-learning-based routing method to discover the best path between different intersections. Finally, vehicles in each road section use a fuzzy logic-based routing technique to choose the foremost relay node. The simulation of QFHR has been executed on the network simulator version 2 (NS2), and its results have been presented in comparison with IRQ, IV2XQ, QGrid, and GPSR in two scenarios. The first scenario analyzes the result based on the packet sending rate (PSR). In this scenario, QFHR gets better the packet delivery rate by 2.74%, 6.67%, 22.35%, and 29.98% and decreases delay by 16.19%, 22.82%, 34.15%, and 59.51%, and lowers the number of hops by 6.74%, 20.09%, 2.68%, and 12.22% compared to IRQ, IV2XQ, QGrid, and GPSR, respectively. However, it increases the overhead by approximately 9.36% and 11.34% compared to IRQ and IV2XQ, respectively. Moreover, the second scenario evaluates the results with regard to the signal transmission radius (STR). In this scenario, QFHR increases PDR by 3.45%, 8%, 23.29%, and 26.17% and decreases delay by 19.86%, 34.26%, 44.09%, and 68.39% and reduces the number of hops by 14.13%, 32.58%, 7.71%, and 21.39% compared to IRQ, IV2XQ, QGrid, and GPSR, respectively. However, it has higher overhead than IRQ (11.26%) and IV2XQ (25%).
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Alikperov, Khanlar D. "ASSOCIATION AS ONE OF THE PHASES OF COGNITIVE ACTIVITY CONSCIOUSNESS IN THE PROCESS OF GENERATING A NEW IDEA (REPRESENTATION OF ASSOCIATIVE THINKING ON THE EXAMPLE OF LAW)." RSUH/RGGU Bulletin. "Literary Theory. Linguistics. Cultural Studies" Series, no. 4 (2022): 355–64. http://dx.doi.org/10.28995/2686-7249-2022-4-355-364.
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The generation of a new idea, developed at the stage of the associative phase of thinking, is carried out through a multi-stage activity of consciousness: the formulation of the problem (hereinafter abbreviated – “P”); insight into the essence of “P” (study, analysis, hypotheses, etc.); isolation from “P” unknown faces; development of an algorithm for finding a way to solve these faces; partial withdrawal from attempts solve “P” by traditional scientific methods; arbitrary transition of “P” with all the accumulated information about it to the subconscious layers of the psyche to search for its solution; search on the subconscious level for the optimal way to solve the “P” and relay the results obtained to consciousness, which has temporarily moved away from its solution; a random figure (form, image, etc.) that suddenly appeared in front of the researcher (at the mental or physical level), not related to the “P” being solved. However, its configuration and individual elements cause associative comparisons with the unresolved “P” and, as it were, prompt the putting forward of new hypotheses about the methods of its solution; maximum activation of the associative impressions that have arisen, their decoding, study, comparison, analysis, identification of connections between them and with “P”; connection of inductive thinking in order to check and streamline the resulting associative versions of the ways to solve “P”; the process of developing a clear verbal formulation of the results of inductive thinking; sudden insight – finding the best way to solve a problem. This far from complete picture of the mechanism of associative generation of correct insight suggests that insight is not at all a generous “gift” of the information field of the Earth or other mysterious forces of nature. Most likely, it is a concentrated fruit of the researcher’s own reflections on the problem, over the solution of which his convolutions “fought” for a long time, which, having reached an emergent state, were transformed into a ready-made solution recipe. The problem under consideration. In other words, the knowledge accumulated by the researcher at a certain stage moves to a qualitatively different level, which, in turn, gives rise to fundamentally new cognitive abilities in him, due to which sometimes (this already depends on the genes) his “Ego” (from the subconscious mind) starts the process enlightenment, the trigger of which is the problem, on the solution of which he is working.
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Gadalińska, Elżbieta, Andrzej Baczmański, Sebastian Wroński, et al. "Neutron Diffraction Study of Elastoplastic Behaviour of Al/SiCp Metal Matrix Composite." Materials Science Forum 905 (August 2017): 66–73. http://dx.doi.org/10.4028/www.scientific.net/msf.905.66.
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The TOF neutron diffraction measurements were done for Al/SiCp metal–matrix composite (17% of SiC) subjected to T6 thermal treatment. Using three separated diffraction peaks of SiC phase and four peaks of Al phase, the lattice strains were measured for both phases independently during in situ tensile test. The experimental results were presented in comparison with elastoplastic model, which allows to find the values of parameters determining plastic deformation of Al matrix (critical resolved shear stress and hardening parameter). Additionally, the results of TOF method were compared with those which were obtained with monochromatic neutron radiation (LLB, Saclay). In the latter experiment Al/SiCp composite containing 25% of SiC was measured. It was shown that after elastoplastic deformation the mismatch stresses determined for both phases relax during tensile deformation.
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Kariyawasam, Sachintha, Jagannath Wijekoon, and Athula Rajapakse. "Assessment of the Performance of Phasor-Based and Transients-Based Faulted Phase Identification Techniques in the Presence of Inverter Interfaced Resources." Energies 16, no. 2 (2023): 640. http://dx.doi.org/10.3390/en16020640.
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Faulted phase identification is one of the segments of conventional system protection that is severely vulnerable in the presence of inverter-based resources (IBR) such as Type IV wind and solar PV power plants. The work presented in this paper investigates the effect of IBRs on the conventional phasor-based faulted phase identification methods widely implemented in contemporary commercial protection relays using theoretical analysis and simulation results. Moreover, this premise is further validated by testing commercial line protection relays using hardware-in-the-loop simulations. This paper also evaluates the applicability of recently proposed transients/incremental quantities-based techniques to overcome the deficiencies of conventional methods to correctly identify the faulted phase in systems with IBRs through real-time and control hardware-in-the-loop simulations. Comparisons with commercial relays show that transient/incremental quantities-based methods are more suitable for systems with a high penetration of IBRs.
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Ding, Jinfeng, Xiao-Yong Zhuge, Yuan Wang, and Anyuan Xiong. "Evaluation of Chinese Aircraft Meteorological Data Relay (AMDAR) Weather Reports." Journal of Atmospheric and Oceanic Technology 32, no. 5 (2015): 982–92. http://dx.doi.org/10.1175/jtech-d-14-00145.1.
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AbstractAircraft Meteorological Data Relay (AMDAR) weather reports are a type of high spatiotemporal data currently widely used in weather monitoring and prediction. A recent Chinese AMDAR project began in 2003 has made rapid progress. However, the assessment and accuracy of these Chinese AMDAR reports have yet to be thoroughly discussed. A comparison of temperature and wind observations between Chinese AMDAR reports and rawinsonde data between 2004 and 2010 is conducted in this paper. Results demonstrate that the root-mean-square error (RMSE) between these two sets of data is 1.40°C for temperature, 3.56 m s−1 for wind speed, and 28° for wind direction. Because of the particularity of observation and inversion method, comparison results are not only affected by AMDAR measurement and reporting error but also by spatial and temporal representativeness, flight phases, and the environment. This evaluation helps create a complete estimation of the accuracy of Chinese AMDAR in order to assist with data assimilation.
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El Ghali, Abdessalem, Claude Bobier, and Noureddine Ben Ayed. "Significance of the E-W fault system in the geodynamic evolution of the Tunisian Alpine Chain foreland. Example of the Sbiba-Cherichira fault system in Central Tunisia." Bulletin de la Société Géologique de France 174, no. 4 (2003): 373–81. http://dx.doi.org/10.2113/174.4.373.
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Abstract The recent sedimentary basins in Central Tunisia correspond to a set of depocenters with complex geometry which are bounded by E-W, N070 and N-S brittle structures. These bordering faults, active during Eocene and Cretaceous times, have been rejuvenated at the end of the Neogene and during Quaternary in a relay pattern system associated with compressive and extensive deformations according to the alternance of extension and compression phases (Tortonian Atlasic Phase of compression, post tectonic top Miocene-early Pleistocene extension associated to the rifting of the Tyrrhenian Basin, and Pleistocene Phase of compression). These tectonic regime changes involve subsidence inversions. Moreover, the neotectonic study carried out along the strike-slip faults corridories and their associated structures enable us : – to precise the timing of the tectonic deformations ; – to establish tectono-sedimentary relationships of Mio-Plio-Quaternary age. Introduction : geodynamical context and objectives of the study. – In Central Tunisia as in the whole Maghreb [Piqué et al., 1998 ; Piqué et al., 2002], the Mesozoic and Cenozoic evolution of sedimentary basins is largely controlled by tectonic heredity due to rejuvenation of basement discontinuities. In fact, previous studies have shown that the normal kinematics activity of The Sbiba-Cherichira fault has governed the opening and the distribution of the Cretaceous and the Eocene basins evolving in a globally extensive tectonic regime [Boltenhagen, 1981 ; El Ghali, 1993]. These old tectonics is proven, also, by the interpretation of NNE-SSW seismic profiles through this collapsed zone [Ben Ayed, 1986, fig. 3] and who reveal that subsidence had been active during the Lower Cretaceous and continued up to the Albian. In the late Miocene and early Quaternary, following the Langhian collision of Sardinia against the Northern Platform of Tunisia [Cohen et al., 1980], the Atlasic and Villafranchian Phases of compression are the most important. They were responsible for the formation of important N040° to N070°E Atlasic folds , N040° to N090°E thrusts , the opening of N120° to N150° E basins parallel to the shortening axis and E-W strike slip fault [Burollet, 1956 ; Ben Ayed, 1986]. In this paper, we present and discuss results of research carried out in the Sbiba-Cherichira area. This research combines interpretation of sedimentological observations and microtectonic or structural field studies [El Ghali et Batik, 1992] carried out along and near the Sbiba-Cherichira faults system, which corresponds to two separated master faults (fig. 2): – the « Southern Sbiba Fault » developed to the west with a direction N090°E which acted as is the southern boundary of the “Sbiba Trough” subsident area as early as the Albian (fig. 3) ; – the “Cherichira Fault” developed to the north-east with a direction N070°E. These faults are connected by the N040°E Labaied-Trozza Fault. Tortonian tectonic activity. – During Tortonian compression (orientation of the shortening axis N120°to N140°E) [Burollet, 1956 ; Ben Ayed, 1986 ; Philip et al., 1986 ; Martinez et al., 1990], many transformations were induced in the studied area (fig. 4a). In fact, the E-W faults of Sbiba and the N070 to N90°E faults of Cherichira, disposed in left relay, were reactivated as dextral strike-slip faults inducing simultaneous distensive deformations (normal faults, grabens, half-grabens…) and compressive ones (folds, reverse faults, overlappings….) localised at fracturing extremity [El Ghali, 1993]. Compressive structures. – The brittle structures are associated with ductile deformations of two types : *The first one corresponds to en echelon folds including : – to the south of the E-W Sbiba Fault, in J. Tiouacha and J. Labaied, Eocene and Neogene strata which are involved in hectometric folds with a N040° to N060°E axial direction (fig. 4a) and an axial westward dip changing from 05° to 60°E ; – to the west of the J. Rebeiba fault, Lutetian and Oligocene to Lower Miocene Strata which are affected by hectometric folds with a N070° to N090°E direction (fig. 4a) and an axial westward dip, changing from 05°to 20°E [El Ghali, 1993]. All these folds are abruptly cut up by the master faults and they can be interpreted as en echelon fault propagation folds. * The second includes plurikilometric folds parallel to the strike slip faults : – the E-W anticline of J. Labaied due to the transpression responsible for reactivation of the southern Sbiba Fault with a dextral strike slip component (fig. 4a); – the N040°E anticline of J. Trozza and the N070°E anticline of J. Cherichira respectively associated with the Trozza-Labaied fault and the Cherichira fault. Because of their orientation approximatively normal to the shortening axis, these faults are reactivated reversed faults giving fault-bend folds [Suppe, 1983] thrusted to the SE with a decollement level in Triassic evaporites extruded along the fault between J. M’Rhila and J. Cherichira (fig. 4a). Distensive structures : syntectonic depocenters associated to dextral strike-slip faults. – The dextral strike-slip faults extremities develop as normal faults N140 to N160°E in the dampening zone (fig. 4a). The east and west endings of Sbiba strike slip fault are two distensive extremities the opening mecanism of which is compatible with that of a megasplit basin at a strike-slip extremity [Harding, 1973 ; Odonne, 1981 ; Granier, 1985 ; Faugère et al., 1986…]. Top Miocene to early Pleistocene tectonic activity. – During upper top Miocene and early Pleistocene times, the Sbiba Trough was characterized by a subsidence more important than in any other place in Tunisia and was filled by continental deposits of the Segui Formation (conglomerates, sands, black clays and lacustrine limestones, fig. 5). Subsidence (500m near Haffouz, 3000m in Sbiba Trough, fig. 4b) was controlled by the activity of synsedimentary normal and strike-slip faults, forming small grabens, monoclinal grabens N090° to N130°E trending often cut by the Sbiba Fault (figs. 4b and 7). This extension can be considered as a post-tectonic extension relative to the Atlasic phase of compression, the orientation of the tensile axis being the same. Pleistocene tectonic activity. – In Central Tunisia, a NNW-SSE compressive phase, intervening in early Quaternary, has been demonstrated out [Burollet, 1956 ; Ben Ayed, 1986 ; Philip et al., 1986]. This “Villafranchian phase” follows distensive strike-slip tectonics of top Miocene Lowermost Pleistocene [El Ghali, 1993] and involves subsidence inversion. This phase is manifested by reverse dextral strike-slip faults on E-W segments (Sbiba and Ain Grab faults, fig. 4c) and by SE vergence overlappings on the NE-SW segments of J. Trozza (fig. 6) and N070°E ones of Cherichira (fig. 8). In other places the top Miocene-early Pleistocene deposits of the Segui Formation are folded, producing in the Sbiba basin N070° to N090°E en echelon folds (fig. 4c) with westward or eastward axial dipping between 05° and 15°. In Jebel Ain Grab area, the folds are overturned and locally thrusted northwards producing a morphostructural dam. This latter limits to the south a sag filled with fluviatile and lacustrine deposits (fig. 9). Comparison with neighbouring regions and conclusions. – The Sbiba-Cherichira faults system correspond to an en-echelon strike slip fault inherited from a basement discontinuity. It recorded most of the main tectonic processes which affected the southern margin of the Tethys. In Central Tunisia, this faults system constitutes an evolution model of one of the major scars which affects the sedimentary cover and controls basins distribution and evolution since the Cretaceous to the Quaternary. * The Tortonian compressional episode corresponding to the Compression Atlasic Phase described from the Rif in Morocco to northern Tunisia [Viguier et al., 1980 ; Philip, 1983 ; Ben Ayed, 1986 ; Morel, 1989 ; Aite, 1995 ; Piqué et al., 2002]. The N120° to N130°E orientation of the shortening axis induced the most important transpression which has triggered the rejuvenation of the Sbiba-Cherichira system as a very active fault driving halokinesis of Triassic evaporites and large development of brittle and folded structures associated to wrench faulting activity as in the eastern platform of Tunisia (fig. 10) [Ellouz, 1984]. * During the top Miocene-early Pleistocene postectonic extension, the rejuvenation of older faults generated a multidirectional extension near the Sbiba-Cherichira faults system as in northern Tunisian platform [Tricart et al., 1994] or in the north-eastern platform and in the strait of Sicily [Bobier et Martin, 1976 ; Ellouz, 1984]. In the Sbiba and Haffouz basins, the multidirectional extension is responsible for the development, along the N070°E dextral strike slip faults and N120°E left lateral strike slip faults, of depocenters for the Segui Formation which is superimposed to Middle Cretaceous subident areas [El Ghali, 1993]. * The Upper-Pleistocene episode which corresponds to the Villafranchian Phase with a N170° to N180°E shortening axis in agreement with the convergence of the European and African Plate and very well documented from the southern margin of Grande Kabilie [Aite, 1995] to northern Tunisia [Ben Ayed, 1986]. Near Sbiba it induced formation of folds, thrusts or reversed faults forming morphostructural dams in which fluvio-lacustrine deposits are accumulated.
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Azouri, Assaf, Volker Roeber, Martin David Guiles, et al. "WAVE-DRIVEN COASTAL DYNAMICS: CAN WE RELY ON PHASE-RESOLVING MODELS?" Coastal Engineering Proceedings, no. 36v (December 28, 2020): 45. http://dx.doi.org/10.9753/icce.v36v.waves.45.
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Wave simulations from two Boussinesq-type models: BOSZ (Roeber & Cheung, 2012) and FUNWAVE (Shi et al., 2012), and a non-hydrostatic model: XBeach (Roelvink et al., 2009), are compared to observational data in a harbor and along the exposed coast of northwest O'ahu Island, Hawai'i, under highly energetic sea/swell forcing conditions. In the present comparison we attempt to address whether the models can (i) reproduce the observed spectra at different locations over a fringing reef and inside a harbor, and; (ii) draw a consistent 2-dimensional picture of the gravity and IG wave fields throughout the computational domain.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/kbbOT0ZpnEo
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Kunas, Beatrix, Oliver Jung, Christoph Schranz, Mathias Schmoigl-Tonis, Manuela Ploessnig, and Anton-Rupert Laireiter. "Personalizing mHealth Interventions for Occupational Stress: Protocol for a Randomized Pilot Study." JMIR Research Protocols 14 (June 3, 2025): e68012. https://doi.org/10.2196/68012.
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Background Occupational stress is associated with detrimental consequences that are addressed by mobile health (mHealth) solutions. Previous developments of apps for occupational stress have not yet fully exploited the potential of multilevel diagnostics through the integration of wearable sensors for interventions. Personalizing mHealth approaches in terms of intervention time and content, which requires the use of artificial intelligence, is the next logical developmental step. The "Relax" approach developed a corresponding prototype of an app-wearable system, which will be evaluated for effectiveness in terms of stress reduction and usability. Objective This study protocol describes an evaluation study used to test the effectiveness and usability of the Relax approach. Methods The evaluation study was designed as a 2-arm randomized trial with 2 phases, each with a 3-week intervention period. In both phases, employees were required to use the app to record daily stress and to wear a wearable sensor to measure heart rate variability. The app offered interventions based on algorithms, which altered the probability of their selection after learning from the data, thereby personalizing the user experience. In the second phase of the study, the sample was divided into 2 groups, varying the degree of personalization of the app. To analyze effectiveness, a 2-factorial mixed within-between design will be applied to compare the outcomes between both groups as well as in a pre-post comparison. In addition, exploratory analyses of the usability of the approach are planned. Results The study was conducted during the spring and summer of 2024, with a total of 46 participants enrolled, and is ready for data analysis. Conclusions The Relax approach, including a number of factors related to personalization that have not yet been incorporated into mHealth in current research, will provide new insights into the next steps of advanced mHealth solutions. Limitations of the study design, such as the lack of a control group and the sample representativity, have to be addressed. Trial Registration Open Science Foundation 10.17605/OSF.IO/MYRD9; https://osf.io/myrd9 International Registered Report Identifier (IRRID) DERR1-10.2196/68012
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Banerjee, Mudita, and Anita Khosla. "Mitigation of magnetising inrush current in three–phase power transformer." Indonesian Journal of Electrical Engineering and Computer Science 20, no. 1 (2020): 39. http://dx.doi.org/10.11591/ijeecs.v20.i1.pp39-45.
Full textAbstract:
<span>During energization of no – load transformers, a high and peaky current flow on the primary side which has rich second harmonics. This current is magnetising inrush current and it is generated when transformer core is driven deep into saturation. This current has various disturbances on transformer attribute; reduced life-span, major voltage drop, insulation weakening, electrical and mechanical vibrations in coils, difficulties in protecting relays and all leads to poor power quality of the electric system. This paper presents the analysis and comparison of recent techniques to reduce the magnitude of inrush current during energization of power transformer. The simulation results are provided for Pre – insertion of resistors, Controlled swithing and Pre – fluxing method. The best method is suggested for mitigating inrush current by simulating in MATLAB/SIMULINK environment.</span>
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Mudita, Banerjee, and Khosla Anita. "Mitigation of magnetising inrush current in three-phase power transformer." Indonesian Journal of Electrical Engineering and Computer Science 20, no. 1 (2020): 39–45. https://doi.org/10.11591/ijeecs.v20.i1.pp39-45.
Full textAbstract:
During energization of no-load transformers, a high and peaky current flow on the primary side which has rich second harmonics. This current is magnetising inrush current and it is generated when transformer core is driven deep into saturation. This current has various disturbances on transformer attribute; reduced life-span, major voltage drop, insulation weakening, electrical and mechanical vibrations in coils, difficulties in protecting relays and all leads to poor power quality of the electric system. This paper presents the analysis and comparison of recent techniques to reduce the magnitude of inrush current during energization of power transformer. The simulation results are provided for Pre-insertion of resistors, Controlled swithing and Pre-fluxing method. The best method is suggested for mitigating inrush current by simulating in MATLAB/SIMULINK environment.
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Alexander, Krasovsky. "Simulation and analysis of improved direct torque control of switched reluctance machine." Indonesian Journal of Electrical Engineering and Computer Science (IJEECS) 18, no. 1 (2020): 251–60. https://doi.org/10.11591/ijeecs.v18.i1.pp251-260.
Full textAbstract:
Direct torque control of electric machines widely used in modern electric drives. Switched reluctance machines (SRM) are different from traditional electric machines, so we cannot apply well-known technical solutions to them. Simulation can provide a powerful approach for investigating the control of switched reluctance machines, and Matlab/Simulink allows it successfully implemented. This paper presents a description of the model and the simulation results of the proposed new algorithms for direct control of the instantaneous torque of SRM in the motor and braking modes. In comparison with the known control algorithms, the proposed algorithm uses one common for all phases relay regulator with a smaller number of switching thresholds and, therefore, it has greater reliability and is easier to set up.
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Jacques, Sébastien, Cédric Reymond, Jean-Charles Le Bunetel, and Ghafour Benabdelaziz. "Comparison of the power balance in a Totem-Pole Bridgeless PFC topology with several inrush current limiting strategies." Journal of Electrical Engineering 72, no. 1 (2021): 12–19. http://dx.doi.org/10.2478/jee-2021-0002.
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Abstract Limiting inrush currents is usually necessary when AC-DC conversion is used to supply DC loads such as battery chargers in particular, it must comply with IEC 61000-3-3. This document discusses the suitability of an active inrush current limiter that can be used to replace traditional thermistors and NTC relays. This strategy is based on the control of the phase shift of thyristor type power components. It has been implemented in a totem-pole bridgeless power factor corrector (PFC). Experimental results show that this solution differs from traditional solutions to ensure high energy efficiency (higher than 95%) while limiting inrush currents.
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Krasovsky, Alexander. "Simulation and analysis of improved direct torque control of switched reluctance machine." Indonesian Journal of Electrical Engineering and Computer Science 18, no. 1 (2020): 251. http://dx.doi.org/10.11591/ijeecs.v18.i1.pp251-260.
Full textAbstract:
<span>Direct torque control of electric machines widely used in modern electric drives. Switched reluctance machines (SRM) are different from traditional electric machines, so we cannot apply well-known technical solutions to them. Simulation can provide a powerful approach for investigating the control of switched reluctance machines, and Matlab / Simulink allows it successfully implemented. This paper presents a description of the model and the simulation results of the proposed new algorithms for direct control of the instantaneous torque of SRM in the motor and braking modes. In comparison with the known control algorithms, the proposed algorithm uses one common for all phases relay regulator with a smaller number of switching thresholds and, therefore, it has greater reliability and is easier to set up. </span>
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ALEXANDER, JAMES C., ANDREW J. BERNOFF, ELIZABETH K. MANN, J. ADIN MANN, JACOB R. WINTERSMITH, and LU ZOU. "Domain relaxation in Langmuir films." Journal of Fluid Mechanics 571 (January 4, 2007): 191–219. http://dx.doi.org/10.1017/s0022112006003326.
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We report on theoretical studies of molecularly thin Langmuir films on the surface of a quiescent subfluid and qualitatively compare the results to both new and previous experiments. The film covers the entire fluid surface, but domains of different phases are observed. In the absence of external forcing, the compact domains tend to relax to circles, driven by a line tension at the phase boundaries. When stretched (by a transient applied stagnation-point flow or by stirring), a compact domain elongates, creating a bola consisting of two roughly circular reservoirs connected by a thin tether. This shape will then relax slowly to the minimum-energy configuration of a circular domain. The tether is never observed to rupture, even when it is more than a hundred times as long as it is wide. We model these experiments by taking previous descriptions of the full hydrodynamics, identifying the dominant effects via dimensional analysis, and reducing the system to a more tractable form. The result is a free boundary problem for an inviscid Langmuir film whose motion is driven by the line tension of the domain and damped by the viscosity of the subfluid. Using this model we derive relaxation rates for perturbations of a uniform strip and a circular patch. We also derive a boundary integral formulation which allows an efficient numerical solution of the problem. Numerically this model replicates the formation of a bola and the subsequent relaxation observed in the experiments. Finally, we suggest physical properties of the system (such as line tension) that can be deduced by comparison of the theory and numerical simulations to the experiment. Two movies are available with the online version of the paper.
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Abbas, Rachid, Caroline Rossoni, Thomas Jaki, Xavier Paoletti, and Pavel Mozgunov. "A comparison of phase I dose-finding designs in clinical trials with monotonicity assumption violation." Clinical Trials 17, no. 5 (2020): 522–34. http://dx.doi.org/10.1177/1740774520932130.
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Background/Aims In oncology, new combined treatments make it difficult to order dose levels according to monotonically increasing toxicity. New flexible dose-finding designs that take into account uncertainty in dose levels ordering were compared with classical designs through simulations in the setting of the monotonicity assumption violation. We give recommendations for the choice of dose-finding design. Methods Motivated by a clinical trial for patients with high-risk neuroblastoma, we considered designs that require a monotonicity assumption, the Bayesian Continual Reassessment Method, the modified Toxicity Probability Interval, the Bayesian Optimal Interval design, and designs that relax monotonicity assumption, the Bayesian Partial Ordering Continual Reassessment Method and the No Monotonicity Assumption design. We considered 15 scenarios including monotonic and non-monotonic dose–toxicity relationships among six dose levels. Results The No Monotonicity Assumption and Partial Ordering Continual Reassessment Method designs were robust to the violation of the monotonicity assumption. Under non-monotonic scenarios, the No Monotonicity Assumption design selected the correct dose level more often than alternative methods on average. Under the majority of monotonic scenarios, the Partial Ordering Continual Reassessment Method selected the correct dose level more often than the No Monotonicity Assumption design. Other designs were impacted by the violation of the monotonicity assumption with a proportion of correct selections below 20% in most scenarios. Under monotonic scenarios, the highest proportions of correct selections were achieved using the Continual Reassessment Method and the Bayesian Optimal Interval design (between 52.8% and 73.1%). The costs of relaxing the monotonicity assumption by the No Monotonicity Assumption design and Partial Ordering Continual Reassessment Method were decreases in the proportions of correct selections under monotonic scenarios ranging from 5.3% to 20.7% and from 1.4% to 16.1%, respectively, compared with the best performing design and were higher proportions of patients allocated to toxic dose levels during the trial. Conclusions Innovative oncology treatments may no longer follow monotonic dose levels ordering which makes standard phase I methods fail. In such a setting, appropriate designs, as the No Monotonicity Assumption or Partial Ordering Continual Reassessment Method designs, should be used to safely determine recommended for phase II dose.
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Liu, Kanghuai, Zhigang Chen, Jia Wu, Yutong Xiao, and Heng Zhang. "Predict and Forward: An Efficient Routing-Delivery Scheme Based on Node Profile in Opportunistic Networks." Future Internet 10, no. 8 (2018): 74. http://dx.doi.org/10.3390/fi10080074.
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In the social scene of opportunistic networks, message applications find suitable relay nodes or certain transmission destinations from the surrounding neighbors through specific network addresses of users. However, at the dawn of big data and 5G networks, the variational location information of nodes is difficult to be available to mobile devices all the time, and a long wait for the destination may cause severe end-to-end delay. To improve the transmission environment, this study constructs an efficient routing-delivery scheme (Predict and Forward) based on node profile for the opportunistic networks. The node profile effectively characterizes nodes by analyzing and comparing their attributes instead of network addresses, such as physical characteristics, places of residence, workplaces, occupations or hobbies. According to the optimal stopping theory, this algorithm implements the optimal transmission for Prelearn messages by dividing the complex data transmission process into two different phases (Predict and Forward). Through simulations and the comparison of routing algorithms in opportunistic networks, the proposed strategy increases the delivery ratio by 80% with the traditional methods on average, and the average end-to-end delay in this algorithm is the lowest.
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Bukhari, Syed Basit Ali, Abdul Wadood, Tahir Khurshaid, Khawaja Khalid Mehmood, Sang Bong Rhee, and Ki-Chai Kim. "Empirical Wavelet Transform-Based Intelligent Protection Scheme for Microgrids." Energies 15, no. 21 (2022): 7995. http://dx.doi.org/10.3390/en15217995.
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Recently, the concept of the microgrid (MG) has been developed to assist the penetration of large numbers of distributed energy resources (DERs) into distribution networks. However, the integration of DERs in the form of MGs disturbs the operating codes of traditional distribution networks. Consequently, traditional protection strategies cannot be applied to MG against short-circuit faults. This paper presents a novel intelligent protection strategy (NIPS) for MGs based on empirical wavelet transform (EWT) and long short-term memory (LSTM) networks. In the proposed NIPS, firstly, the three-phase current signals measured by protective relays are decomposed into empirical modes (EMs). Then, various statistical features are extracted from the obtained EMs. Afterwards, the extracted features along with the three-phase current measurement are input to three different LSTM network to obtain exact fault type, phase, and location information. Finally, a trip signal based on the obtained fault information is generated to disconnect the faulty portion from the rest of the MG. The significant feature of the proposed NIPS is that it does not need adaptive relaying and communication networks. Moreover, it is independent of the operating scenario and hence fault current magnitude. To evaluate the efficacy of the proposed NIPS, exhaustive simulations are performed on an international electro-technical commission (IEC) MG. The simulation results confirm the efficiency of the proposed NIPs in terms of accuracy, dependability, and security. Moreover, comparisons with existing intelligent protection schemes validate that the proposed NIPS is highly accurate, secure, and dependable.
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Ruiz, L. M., J. Arévalo, J. Parada, et al. "Respirometric assays of two different MBR (microfiltration and ultrafiltration) to obtain kinetic and stoichiometric parameters." Water Science and Technology 63, no. 11 (2011): 2478–85. http://dx.doi.org/10.2166/wst.2011.578.
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A comparison of two different medium scale MBRs (ultrafiltration and microfiltration) using respirometric methods has been achieved. The ultrafiltration membrane plant (0.034 µm pore size) maintained recirculation sludge flow at seven times the influent flow, and membranes were backwashed every 5 min and chemically cleaned weekly. The microfiltration membrane plant (0.4 µm pore size) maintained recirculation sludge flow at four times the influent flow, membrane-relax was applied after the production phase and membranes were chemically cleaned in the event of high trans-membrane pressure. Both technologies showed a similar performance with regard to heterotrophic kinetic and stoichiometric parameters and organic matter effluent concentrations. The influent was characterized by means of its COD fractions and the average removal percentages for COD concentrations were around 97% for both plants in spite of influent COD fluctuation, temperature variations and sludge retention time (SRT) evolution. Both SRT evolution and temperature affect the heterotrophic yield (YH) and the decay coefficient (bH) in the same range for both plants. YH values of over 0.8 mg COD/mg COD were obtained during the unsteady periods, while under steady state conditions these values fell to less than 0.4 mg COD/mg COD. bH by contrast reached values of less than 0.05 d−1.
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Tarchi, Daniele, Arash Bozorgchenani, and Mulubrhan Desta Gebremeskel. "Zero-Energy Computation Offloading with Simultaneous Wireless Information and Power Transfer for Two-Hop 6G Fog Networks." Energies 15, no. 5 (2022): 1632. http://dx.doi.org/10.3390/en15051632.
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Currently, we are faced with an ever-increasing number of devices and objects connected to the Internet aimed at creating the so-called Internet of Things framework, fostering the creation of a connected world of objects. One of the main challenges we are actually facing is constituted by the constrained sizes of such objects: reduced memory, reduced computational capacity, and reduced battery sizes. Particular attention should be devoted to energy efficiency, since a potential energy shortage would negatively impact not only its operation but also network-wide operation, considering the tight connections among any object. According to the 6G system’s use-case related to self-sustainability and zero-energy networks, this paper focuses on an energy-efficient fog network architecture for IoT scenarios, jointly implementing computation offloading operations and simultaneous wireless information and power Transfer (SWIPT), hence, enabling the possibility of jointly transferring energy and computational tasks among the nodes. The system under consideration is composed of three nodes, where an access point (AP) is considered to be always connected to the power network, while a relay node and an end node can harvest energy from the AP. The proposed solution allows to jointly optimize the computation offloading and the energy harvesting phases while maximizing the network lifetime, so as to maximize the operational time of the network. Numerical results obtained on MATLAB demonstrate that the proposed algorithm performs better than the other benchmarks considered for comparison.
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Xie, Wenqiang, Mingming Shi, Yuying He, Chenyu Zhang, and Ruihuang Liu. "Comparison of Configurable Modular Two-Level and Three-Level Isolated Bidirectional DC–DC Converters for Super-Capacitor Charging in DC Shore Power Systems." Energies 17, no. 18 (2024): 4630. http://dx.doi.org/10.3390/en17184630.
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Compared to the AC counterpart, the DC shore power system provides a significant advantage of efficient power supply from renewable sources to ships and onshore loads. Super-capacitors serve as key energy storage units in such a system to buffer the power fluctuations and collect the regenerative energy. However, the ultra-wide voltage range of super-capacitors imposes a significant challenge in the topology selection and efficiency optimization of the interfacing isolated bidirectional DC–DC converter. To tackle this challenge, this paper analyzes and compares two promising converter topologies, which are a configurable modular two-level dual-active bridge (CM-2L-DAB) and a three-level dual-active bridge (3L-DAB). To facilitate an ultra-wide voltage range, extended phase-shift (EPS) modulation in conjunction with the topology reconfiguration is analyzed for the CM-2L-DAB, while a hybrid modulation scheme is proposed for the 3L-DAB. A unified design approach is provided for both topologies, which also yields to the power loss modeling. On this basis, the CM-2L-DAB and 3L-DAB are thoroughly compared in terms of the modulation schemes, current stress, soft-switching operation, power conversion efficiency, material usage, closed-loop control scheme, and reliability. A prominent conclusion can be drawn that the CM-2L-DAB provides a higher efficiency than the 3L-DAB over the whole voltage range, but it relies on additional relays to reconfigure its topology which results in lower reliability and dynamic performance than the 3L-DAB.
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Chabolla, S. A., C. W. Machan, J. Yin, et al. "Bio-inspired CO2reduction by a rhenium tricarbonyl bipyridine-based catalyst appended to amino acids and peptidic platforms: incorporating proton relays and hydrogen-bonding functional groups." Faraday Discussions 198 (2017): 279–300. http://dx.doi.org/10.1039/c7fd00003k.
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Herein, we report a new approach to bio-inspired catalyst design. The molecular catalyst employed in these studies is based on the robust and selective Re(bpy)(CO)<sub>3</sub>Cl-type (bpy = 2,2′-bipyridine) homogeneous catalysts, which have been extensively studied for their ability to reduce CO<sub>2</sub>electrochemically or photochemically in the presence of a photosensitizer. These catalysts can be highly active photocatalysts in their own right. In this work, the bipyridine ligand was modified with amino acids and synthetic peptides. These results build on earlier findings wherein the bipyridine ligand was functionalized with amide groups to promote dimer formation and CO<sub>2</sub>reduction by an alternate bimolecular mechanism at lower overpotential (ca.250 mV) than the more commonly observed unimolecular process. The bio-inspired catalysts were designed to allow for the incorporation of proton relays to support reduction of CO<sub>2</sub>to CO and H<sub>2</sub>O. The coupling of amino acids tyrosine and phenylalanine led to the formation of two structurally similar Re catalyst/peptide catalysts for comparison of proton transport during catalysis. This article reports the synthesis and characterization of novel catalyst/peptide hybrids by molecular dynamics (MD simulations of structural dynamics), NMR studies of solution phase structures, and electrochemical studies to measure the activities of new bio-inspired catalysts in the reduction of CO<sub>2.</sub>