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1
Ma, Jun, Huxin Qin, Xinlin Song, and Runtong Chu. "Pattern selection in neuronal network driven by electric autapses with diversity in time delays." International Journal of Modern Physics B 29, no. 01 (December 18, 2014): 1450239. http://dx.doi.org/10.1142/s0217979214502397.
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The electric activity of neuron and collective behaviors of neurons can be modulated by autapse, which can be described by self-feedback current in close loop with time delay being considered. Distribution of electric autapses in a local area can introduce heterogeneity in the network and thus traveling wave emits from this area. In this paper, diversity in time delay of electric autapse is considered and collision between emitting waves from different local areas driven by electric autapses under different time delays is observed. In the numerical studies, neurons in the square area with 15×15 (and/or 20×20) nodes are connected electric autapses with different time delays and target-like waves are induced and converted into, spiral waves after continuous collision between wave fronts. It is found that a group of spiral waves can emerge in the network, or coexist with target waves under appropriate coupling intensity due to time delay diversity in autapse and these waves can regulate the collective behaviors of neurons as continuous pacemakers.
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Kumar, Ranjeet, and D. Saxena. "Fault location in distribution network using travelling waves." International Journal of Energy Sector Management 13, no. 3 (September 2, 2019): 651–69. http://dx.doi.org/10.1108/ijesm-07-2018-0007.
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Purpose An electrical power distribution network is expected to deliver uninterrupted power supply to the customers. The disruption in power supply occurs whenever there is a fault in the system. Therefore, fast fault detection and its precise location are necessary to restore the power supply. Several techniques are proposed in the past for fault location in distribution network but they have limitations as their fault location accuracy depends on system conditions. The purpose of this paper is to present a travelling wave-based fault location method, which is fast, accurate and independent of system conditions. Design/methodology/approach This paper proposes an effective method for fault detection, classification and location using wavelet analysis of travelling waves for a multilateral distribution network embedded with distributed generation (DG) and electric vehicle (EV) charging load. The wavelet energy entropy (WEE) is used for fault detection and classification purpose, and wavelet modulus maxima (WMM) of aerial mode component is used for faulted lateral identification and exact fault location. Findings The proposed method effectively detects and classifies the faults, and accurately determines the exact fault location in a multilateral distribution network. It is also found that the proposed method is robust and its accuracy is not affected by the presence of distributed generation and electric vehicle charging load in the system. Originality/value Travelling wave based method for fault location is implemented for a multilateral distribution network containing distributed generation and electric vehicle load. For the first time, a fault location method is tested in the presence of EV charging load in distribution network.
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Dayaday, Maricel G., and Jordan-James S. Olivo. "Sound to electric energy generating device." Indonesian Journal of Electrical Engineering and Computer Science 22, no. 3 (June 1, 2021): 1761. http://dx.doi.org/10.11591/ijeecs.v22.i3.pp1761-1769.
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This paper presents the potential of an electromagnetic transducer device in a form of audio speaker that is used to capture sound waves to be converted into electricity. It is an interesting concept but less explored by researchers. The objective of the study is to measure the potential of electromagnetic transducer as a way to generate electricity. It deals with the creation of electricity through movement and magnetism. Sound waves can induce movement on the surface which in turn moves the transducer thus creating electricity. The source of sound was coming from an 8-inch subwoofer speaker with a frequency of 80 Hz that was held constant throughout the experiment. Furthermore, using simple linear regression analysis, the study showed that for every linear increase of sound intensity level and distance of the source, there is an exponential increase and an exponential decrease in the voltage root mean square (RMS) respectively. The functionality assessment of the device was statistically analyzed using completely randomized design. It was found that the energy level significantly increased as the sound intensity level increases given a fixed distance of 15 mm from the source. The device could generate enough energy to power small electronics such as light emitting diodes (LED), transistor and resistor.
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Panova, Olena, Nataliia Burdeina, Kyrylo Nikolaiev, and Yana Biruk. "PLANNING AND IMPLEMENTATION OF ELECTROMAGNETIC SAFETY MEASURES IN INDUSTRIAL BUILDINGS AND STRUCTURE." JOURNAL of Donetsk mining institute, no. 2 (2020): 155–61. http://dx.doi.org/10.31474/1999-981x-2020-2-155-161.
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Objective. Identification of factors of non-productive origin that affect the electromagnetic situation in industrial buildings and the implementation of a sequence of measures to normalize it. Methods. Experimental study of the source of extraneous electromagnetic fields in buildings and structures that can adversely affect workers and sensitive devices in production. To do this, the means of finding such fields were identified and used. The state and description of electric power networks as well as the distribution of the intensity of high-frequency electromagnetic fields are generalized. Electromagnetic safety measures in the production of various purposes are analyzed and presented. Results. Industrial five-storey buildings were inspected for currents in metal structures. The results show that they have significant levels of electric currents in metal structures depending on the riser of the building. It is established that the precondition for the application of safety measures is the analysis of the state of electric power networks, the distribution of the intensity of high-frequency electromagnetic fields, etc. The levels of electromagnetic fields in partially shielded rooms have been experimentally established. Typical dependences of radiation intensity of mobile phones on the signal level from base stations are obtained. The conditions of normalization of the electromagnetic situation in individual rooms and the building as a whole are substantiated. Electromagnetic safety measures have been introduced. Scientific novelty. To minimize the impact of electrical networks on the electromagnetic environment in the building, it is advisable to upgrade it according to the scheme TN-S, or TN-C-S, which reduces the levels of uncompensated electric currents in the network and the corresponding magnetic fields. Practical significance. It is established that: a) it is obligatory to determine the presence of leakage electric currents on grounded bearing structures and engineering networks that generate magnetic fields of hygienically significant voltages; b) reducing the levels of these jets due to technical solutions further reduces the intensity of electro-like processes in metal structures; c) to reduce the levels of high-frequency electromagnetic fields in production facilities, which are formed due to the reflection and re-reflection of electromagnetic waves, it is advisable to use composite shielding materials with controlled absorption and reflection coefficients. This approach will systematize the overall electromagnetic background in the premises and the building as a whole.
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Khuziashev, Rustem, Igor Kuzmin, and Iluza Irkagalieva. "Classification of diagnostic features of transient signals in the electric power industry." E3S Web of Conferences 288 (2021): 01036. http://dx.doi.org/10.1051/e3sconf/202128801036.
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Problems of practical implementation of traveling wave fault location caused by the registration of signals of different nature are considered. Analysis of the experimentally recorded traveling waves made it possible to divide them into 4 groups caused by partial discharges, lightning overvoltages, scheduled switching and fault commutations. The network dispatchers only needs the fault commutation information. Traveling waves recorded near the place of their origin have different meanings of diagnostic signs. The magnitude of the pre-alarm noise, the number of pulses in the signal and the duration of the signal are used as diagnostic indicators. These three diagnostic signs allow one to recognize each of the 4 causes of the travelling waves.
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Li, Lin, Zhou Jiang, Yu Fan, and Jun Li. "Creating the Coupled Band Gaps in Piezoelectric Composite Plates by Interconnected Electric Impedance." Materials 11, no. 9 (September 7, 2018): 1656. http://dx.doi.org/10.3390/ma11091656.
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In this paper, we investigate the coupled band gaps created by the locking phenomenon between the electric and flexural waves in piezoelectric composite plates. To do that, the distributed piezoelectric materials should be interconnected via a ‘global’ electric network rather than the respective ‘local’ impedance. Once the uncoupled electric wave has the same wavelength and opposite group velocity as the uncoupled flexural wave, the desired coupled band gap emerges. The Wave Finite Element Method (WFEM) is used to investigate the evolution of the coupled band gap with respect to propagation direction and electric parameters. Further, the bandwidth and directionality of the coupled band gap are compared with the LR and Bragg gaps. An indicator termed ratio of single wave (RSW) is proposed to determine the effective band gap for a given deformation (electric, flexural, etc.). The features of the coupled band gap are validated by a forced response analysis. We show that the coupled band gap, despite directional, can be much wider than the LR gap with the same overall inductance. This might lead to an alternative to adaptively create band gaps.
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Meng, Ming, Wei Shang, and Dongxiao Niu. "Monthly Electric Energy Consumption Forecasting Using Multiwindow Moving Average and Hybrid Growth Models." Journal of Applied Mathematics 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/243171.
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Monthly electric energy consumption forecasting is important for electricity production planning and electric power engineering decision making. Multiwindow moving average algorithm is proposed to decompose the monthly electric energy consumption time series into several periodic waves and a long-term approximately exponential increasing trend. Radial basis function (RBF) artificial neural network (ANN) models are used to forecast the extracted periodic waves. A novel hybrid growth model, which includes a constant term, a linear term, and an exponential term, is proposed to forecast the extracted increasing trend. The forecasting results of the monthly electric energy consumption can be obtained by adding the forecasting values of each model. To test the performance by comparison, the proposed and other three models are used to forecast China's monthly electric energy consumption from January 2011 to December 2012. Results show that the proposed model exhibited the best performance in terms of mean absolute percentage error (MAPE) and maximal absolute percentage error (MaxAPE).
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Choroszucho, Agnieszka. "Analysis of the influence of the complex structure of clay hollow bricks on the values of electric field intensity by using the FDTD method." Archives of Electrical Engineering 65, no. 4 (December 1, 2016): 745–59. http://dx.doi.org/10.1515/aee-2016-0052.
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Abstract The study presents the analysis of the effects occurring at the propagation of electromagnetic waves within an area containing non-ideal, non-homogenous and absorbing dielectric. The analysed models are connected with housing constructions and include single and double-layered walls made of clay hollow bricks. The influence of the size of holes, the contained clay mass percentage and conductivity of brick on the distribution of electric field is presented. Double-layered wall causes more heterogeneity in distribution of electric field and numerous maxima and minima to compare with singlelayered construction. The presented results refer to the electromagnetic field generated by a wireless communication system (Wi-Fi), operating within the standard frequencies (2.4 GHz and 5 GHz). A FDTD method was used to the analysis of electric field distribution. Also in this paper all formulations of difference method (FDTD) is presented. The possibilities of modifying the described method are indicated too. The obtained values of electric field intensity allow to determining the attenuation coefficient for different variants of the walls. Detailed analysis of influence of different types of building construction will make it possible to better understand the wave phenomena and counteract local fading at planning of wireless networks systems.
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Lei, Wanjun, Yanxia Wang, Lu Wang, and Hui Cao. "A Fundamental Wave Amplitude Prediction Algorithm Based on Fuzzy Neural Network for Harmonic Elimination of Electric Arc Furnace Current." Mathematical Problems in Engineering 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/268470.
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Electric arc furnace (EAF) causes the harmonics to impact on the supply network greatly and harmonic elimination is a very important research work for the power quality associated with EAF. In the paper, a fundamental wave amplitude prediction algorithm based on fuzzy neural network for harmonic elimination of EAF current is proposed. The proposed algorithm uses the learning ability of the neural network to refine Takagi-Sugeno type fuzzy rules and the inputs are the average of the current measured value in different time intervals. To verify the effectiveness of the proposed algorithm, some experiments are performed to compare the proposed algorithm with the back-propagation neural networks, and the field data collected at an EAF are used in the experiments. Moreover, the measured amplitudes of fundamental waves of field data are obtained by the sliding-window-based discrete Fourier transform on the field data. The experiments results show that the proposed algorithm has higher precision. The real curves also verify that the amplitude of fundamental wave current could be predicted accurately and the harmonic elimination of EAF would be realized based on the proposed algorithm.
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Yang, Yi, Zhihao Shang, Yao Chen, and Yanhua Chen. "Multi-Objective Particle Swarm Optimization Algorithm for Multi-Step Electric Load Forecasting." Energies 13, no. 3 (January 21, 2020): 532. http://dx.doi.org/10.3390/en13030532.
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As energy saving becomes more and more popular, electric load forecasting has played a more and more crucial role in power management systems in the last few years. Because of the real-time characteristic of electricity and the uncertainty change of an electric load, realizing the accuracy and stability of electric load forecasting is a challenging task. Many predecessors have obtained the expected forecasting results by various methods. Considering the stability of time series prediction, a novel combined electric load forecasting, which based on extreme learning machine (ELM), recurrent neural network (RNN), and support vector machines (SVMs), was proposed. The combined model first uses three neural networks to forecast the electric load data separately considering that the single model has inevitable disadvantages, the combined model applies the multi-objective particle swarm optimization algorithm (MOPSO) to optimize the parameters. In order to verify the capacity of the proposed combined model, 1-step, 2-step, and 3-step are used to forecast the electric load data of three Australian states, including New South Wales, Queensland, and Victoria. The experimental results intuitively indicate that for these three datasets, the combined model outperforms all three individual models used for comparison, which demonstrates its superior capability in terms of accuracy and stability.
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Zhai, Xue Ming, Huan Xia, and Long An. "A Distribution Network Fault Location Method Based on Reverse Wave and Wavelet Analysis." Applied Mechanics and Materials 713-715 (January 2015): 1369–72. http://dx.doi.org/10.4028/www.scientific.net/amm.713-715.1369.
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Based on the analysis of the transient process of the electric line’s developing ground fault, this paper applies the oppositely-directed travelling wave fault location method to fault location in distribution network. Simultaneously, this paper chooses proper wavelet generating functions to find the modulus maximum of oppositely-directed travelling waves and summarizes the methods and steps of this oppositely-directed travelling wave fault location. Finally, PSCAD/EMTDC is used to simulate the single-phase ground fault to verify the oppositely-directed travelling wave fault location method.
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Widyastuti, Christine, and I. Nyoman Bagus Yudha Dharma. "Dampak Korona pada SUTET 500 kV Terhadap Radio Interference." Energi & Kelistrikan 11, no. 2 (December 20, 2019): 87–97. http://dx.doi.org/10.33322/energi.v11i2.842.
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Corona can occur in SUTET because SUTET carries a high enough electric current and voltage, this causes excessive electrical pressure that is not proportional to the breakdown strength of the air around the conductor so that there will be a phenomenon where the electric field will collide with free electrons in the air and will form ionisations in the form of new ions and electrons. This process will continue as long as there are currents and voltages on the extra-high-voltage network. This certainly will affect the surrounding environment through which SUTET is included, among others, interference with radio waves (Radio Interference). The addition of the number of sub conductors is considered more effective in reducing corona losses and radio interference in each wicket than increasing the distance of the conductor to the ground. The impact of corona on a 500 kV double-channel SUTET on radio interference in the Greater Jakarta area is still within reasonable limits because it is still below the IEEE standard of 40 dB.
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Hidayat, M. Reza, Mohamad Hamzah Zamzam, and Salita Ulitia Prini. "Excitation Analysis of Transverse Electric Mode Rectangular Waveguide." Jurnal Elektronika dan Telekomunikasi 20, no. 1 (August 31, 2020): 1. http://dx.doi.org/10.14203/jet.v20.1-8.
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A waveguide is a transmission medium in the form of a pipe and is made from a single conductor. A waveguide has the function of delivering electromagnetic waves with a frequency of 300 MHz - 300 GHz and is able to direct the waves in a particular direction. In its development, a waveguide can be used as a filter. A filter consists of several circuits designed to pass signals that are generated at a specific frequency and attenuate undesired signals. One type of filter that can pass a signal in a particular frequency range and block signals that are not included in that frequency range is a bandpass filter. In this article, we study a rationing analysis on rectangular waveguide using TEmn mode followed by an implementation of a bandpass filter in the frequency range of 3.3-3.5 GHz for S-Band Wireless Broadband and Fixed Satellite. The observation process is done by shifting the position of the connector (power supply) as much as five times the shift to get the results as desired. Based on the analysis of the simulation process using Ansoft HFSS software, it is observed that the optimized results of the rectangular waveguide mode TE10 were obtained at a distance between connectors of 30 mm with a cut-off frequency of 3.3 GHz, the value of the return loss parameter of -34.442 dB and an insertion loss of -0.039 dB. Whereas, the optimized TE20 mode can be obtained at a distance of 70 mm between connectors, with a cut-off frequency of 3.5 GHz, the value of the return loss parameter of -28.718 dB and an insertion loss of -0.045. The measurement of TE10 mode in our Vector Network Analyzer (VNA) shows a cut-off frequency of 3.2 GHz, with a value of the return loss of -18.73 dB and an insertion loss of -2.70 dB. Meanwhile, a measurement of TE20 mode results in a cut-off frequency of 3.2 GHz, with a value of the return loss of -5.89 dB and an insertion loss of -4.31 dB.
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Min, Sun-Hong, Jung-Il Kim, Matlabjon Sattorov, Seontae Kim, Dongpyo Hong, Seonmyeong Kim, Bong-Hwan Hong, et al. "Dependence of Irradiated High-Power Electromagnetic Waves on the Failure Threshold Time of Semiconductors Using a Closed Waveguide." Electronics 10, no. 16 (August 6, 2021): 1884. http://dx.doi.org/10.3390/electronics10161884.
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The failure threshold time of semiconductors caused by the impact of irradiated high-power electromagnetic waves (HPEM) is experimentally studied. A SN7442 integrated circuit (IC) is placed in an emulator with a WR430 closed waveguide and is irradiated by HPEM generated from a magnetron oscillator. The state of the SN7442 component is observed by a light-emitting diode (LED) detector and the voltage measured in the SN7442 component. As the magnitude of the electric field in the HPEM is varied from 24 kV/m to 36 kV/m, the failure threshold time falls from 195 s to 17 s with dependence of the irradiated electric field (E) on the failure threshold time (T) from T~E−12 to a T~E−6.
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Iida, Takahito, and Masashi Kashiwagi. "Small water channel network for designing wave fields in shallow water." Journal of Fluid Mechanics 849 (June 15, 2018): 90–110. http://dx.doi.org/10.1017/jfm.2018.355.
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A small water channel network is proposed for designing shallow water fields, and the network is applied to attain water wave cloaking. The design formula is derived from an analogy between waves in a water channel and in an electric circuit; an approach of a transmission line metamaterial is extended to water waves and the water channel is used as an alternative of the transmission line. The size of the water channel is sufficiently smaller than the wavelength and a number of the channels are periodically connected as a network. This small water channel network makes artificial wave fields, and it works for a wide band of frequencies. First, we make an isotropic network equivalent to a shallow water space with constant depth in order to validate the proposed design method. It shows no wave reflection at the interface due to impedance matching. After that, the proposed theory is applied to designing an anisotropic small water channel network for demonstrating shallow water cloaking. A cylinder is cloaked from waves by the network surrounding the cylinder. Both cases are confirmed with numerical computations by solving the boundary-value problem based on linear potential theory.
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Otsuka, Y., K. Suzuki, S. Nakagawa, M. Nishioka, K. Shiokawa, and T. Tsugawa. "GPS observations of medium-scale traveling ionospheric disturbances over Europe." Annales Geophysicae 31, no. 2 (February 5, 2013): 163–72. http://dx.doi.org/10.5194/angeo-31-163-2013.
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Abstract. Two-dimensional structures of medium-scale traveling ionospheric disturbances (MSTIDs) over Europe have been revealed, for the first time, by using maps of the total electron content (TEC) obtained from more than 800 GPS receivers of the European GPS receiver networks. From statistical analysis of the TEC maps obtained 2008, we have found that the observed MSTIDs can be categorized into two groups: daytime MSTID and nighttime MSTID. The daytime MSTID frequently occurs in winter. Its maximum occurrence rate in monthly and hourly bin exceeds 70% at lower latitudes over Europe, whereas it is approximately 45% at higher latitudes. Since most of the daytime MSTIDs propagate southward, we speculate that they could be caused by atmospheric gravity waves in the thermosphere. The nighttime MSTIDs also frequently occur in winter but most of them propagate southwestward, in a direction consistent with the theory that polarization electric fields play an important role in generating the nighttime MSTIDs. The nighttime MSTID occurrence rate shows distinct latitudinal difference: The maximum of the occurrence rate in monthly and hourly bin is approximately 50% at lower latitudes in Europe, whereas the nighttime MSTID was rarely observed at higher latitudes. We have performed model calculations of the plasma density perturbations caused by a gravity wave and an oscillating electric field to reproduce the daytime and nighttime MSTIDs, respectively. We find that TEC perturbations caused by gravity waves do not show dip angle dependencies, while those caused by the oscillating electric field have a larger amplitude at lower latitudes. These dip angle dependencies of the TEC perturbation amplitude could contribute to the latitudinal variation of the MSTID occurrence rate. Comparing with previous studies, we discuss the longitudinal difference of the nighttime MSTID occurrence rate, along with the E- and F-region coupling processes. The seasonal variation, of the nighttime MSTID occurrence rate in Europe, is not consistent with the theory that the longitudinal and seasonal variations of the nighttime MSTID occurrence could be attributed to those of the Es layer occurrence.
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Pilipenko, V. A., E. N. Fedorov, M. Teramoto, and K. Yumoto. "The mechanism of mid-latitude Pi2 waves in the upper ionosphere as revealed by combined Doppler and magnetometer observations." Annales Geophysicae 31, no. 4 (April 17, 2013): 689–95. http://dx.doi.org/10.5194/angeo-31-689-2013.
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Abstract. The interpretation of simultaneous ionospheric Doppler sounding and ground magnetometer observations of low-latitude Pi2 waves is revised. We compare the theoretical estimates of the ionospheric Doppler velocity for the same amplitude of the ground magnetic disturbances produced by a large-scale compressional mode and an Alfvén mode. The plasma vertical displacement caused by the wave electric field is shown to be the dominating effect. Taking into account the correction of the previous paper, the observations of low-latitude Pi2 in the F layer ionosphere by Doppler sounding and SuperDARN (Super Dual Auroral Radar Network) radars give consistent results. We suggest that the Doppler response to Pi2 waves is produced by the Alfvén wave component, but not the fast-mode component, whereas the ground magnetic signal is composed from both Alfvén and fast magnetosonic modes.
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Krayni, Anis, Abdelhamid Hadjem, Günter Vermeeren, Alain Sibille, Christophe Roblin, Wout Joseph, Luc Martens, and Joe Wiart. "Modeling and Characterization of the Uplink and Downlink Exposure in Wireless Networks." International Journal of Antennas and Propagation 2017 (2017): 1–15. http://dx.doi.org/10.1155/2017/8243490.
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This paper deals with a new methodology to assess the exposure induced by both uplink and downlink of a cellular network using 3D electromagnetic simulations. It aims to analyze together the exposure induced by a personal device (uplink exposure) and that induced by a base station (downlink exposure). The study involved the major parameters contributing to variability and uncertainty in exposure assessment, such as the user’s posture, the type of wireless device, and the propagation environment. Our approach is relying basically on the modeling of the power radiated by the personal device and the ambient electric field, while taking into account the effects of human body shadowing and the propagation channel fluctuations. The exposure assessment as well as the human-wave interactions has been simulated using the finite difference in time domain method (FDTD). In uplink scenarios, four FDTD simulations were performed with a child model, used in two postures (sitting and standing) and in two usage scenarios (voice and data), which aimed to examine the exposure induced by a mobile phone and a tablet emitting, respectively, at 900 MHz and 1940 MHz. In the downlink scenario, a series of FDTD simulations of an exposure to a single plane wave and multiplane waves have been conducted, and an efficient metamodeling of the exposure using the Polynomial Chaos approach has been developed.
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Gao, Yin Han, Ju Xian Wang, Kai Yu Yang, Tian Hao Wang, and Zhan Yang An. "The Analysis and Simulation of Contact Loss between Pantograph and Catenary on Electric Railway." Applied Mechanics and Materials 713-715 (January 2015): 1277–80. http://dx.doi.org/10.4028/www.scientific.net/amm.713-715.1277.
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Based on the classical Mayer-arc model, this paper establishes the equivalent circuit of traction network for AC25kV electric railway from the essence of contact loss discharge. The voltage waves of contact loss arc at different moments are obtained by MATLAB/simulink. Through the analysis, it can be confirmed that the EMI (electromagnetic interference) with broad band and high amplitude will appear at the moment the contact loss between pantograph and catenary happens. Finally, relevant measures are given to avoid the probability event of contact loss.
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Banaseka, Frank Kataka, Ferdinand Katsriku, Jamal Deen Abdulai, Kofi Sarpong Adu-Manu, and Felicia Nana Ama Engmann. "Signal Propagation Models in Soil Medium for the Study of Wireless Underground Sensor Networks: A Review of Current Trends." Wireless Communications and Mobile Computing 2021 (April 2, 2021): 1–12. http://dx.doi.org/10.1155/2021/8836426.
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Radio signal propagation modeling plays an important role in the design of wireless communication systems. Various models have been developed, over the past few decades, to predict signal propagation and behavior for wireless communication systems in different operating environments. Recently, there has been an interest in the deployment of wireless sensors in soil. To fully exploit the capabilities of sensor networks deployed in soil requires an understanding of the propagation characteristics within this environment. This paper reviews the cutting-edge developments of signal propagation in the subterranean environment. The most important modeling techniques for modeling include electromagnetic waves, propagation loss, magnetic induction, and acoustic wave. These are discussed vis-a-vis modeling complexity and key parameters of the environment including electric and magnetic properties of soil. An equation to model propagation in the soil is derived from the free space model. Results are presented to show propagation losses and at different frequencies and volumetric water content. The channel capacity and the operating frequency are also analyzed against soil moisture at different soil types and antenna sizes.
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My, D. T. T., H. N. B. Phuong, T. T. Huong, and B. T. M. Tu. "A Magneto-Electric Dipole Antenna Array for Millimeter Wave Applications." Engineering, Technology & Applied Science Research 10, no. 4 (August 16, 2020): 6057–61. http://dx.doi.org/10.48084/etasr.3710.
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In this paper, a low-profile broadband antenna is proposed for future 5G millimeter-wave cellular wireless networks. The proposed antenna is a modified Magneto-Electric (ME) dipole, which consists of four metallic plates, grounded vias, an aperture fed, a ground plane, and a microstrip line feed. The antennas are built on RT/Duroid 5880 substrates and have been realized by the printed circuit board technique. A single-element with an overall of 10×10×1.04mm3 (~1.26λo×1.26λo×0.13λo at 38GHz) exhibits an impedance matching of 27.9% (32.2-42.8GHz) for |S11|<–10dB and a realized gain up to 7.5dBi over the frequency band. The usefulness of these antennas as beamforming radiators is demonstrated by a 1×4 element linear array. Also, a wide-band excitation is applied for the linear ME dipole array to realize a broadband array. The simulated results proved the proposed array can operate in a frequency band spreading from 31.4GHz to 42.1GHz with a gain of 12.5dBi and a side-lobe of -13dB
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Abe, Jair Minoro, Helder Frederico da Silva Lopes, and Renato Anghinah. "Paraconsistent artificial neural networks and Alzheimer disease: A preliminary study." Dementia & Neuropsychologia 1, no. 3 (September 2007): 241–47. http://dx.doi.org/10.1590/s1980-57642008dn10300004.
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Abstract EEG visual analysis has proved useful in aiding AD diagnosis, being indicated in some clinical protocols. However, such analysis is subject to the inherent imprecision of equipment, patient movements, electric registers, and individual variability of physician visual analysis. Objectives: To employ the Paraconsistent Artificial Neural Network to ascertain how to determine the degree of certainty of probable dementia diagnosis. Methods: Ten EEG records from patients with probable Alzheimer disease and ten controls were obtained during the awake state at rest. An EEG background between 8 Hz and 12 Hz was considered the normal pattern for patients, allowing a variance of 0.5 Hz. Results: The PANN was capable of accurately recognizing waves belonging to Alpha band with favorable evidence of 0.30 and contrary evidence of 0.19, while for waves not belonging to the Alpha pattern, an average favorable evidence of 0.19 and contrary evidence of 0.32 was obtained, indicating that PANN was efficient in recognizing Alpha waves in 80% of the cases evaluated in this study. Artificial Neural Networks - ANN - are well suited to tackle problems such as prediction and pattern recognition. The aim of this work was to recognize predetermined EEG patterns by using a new class of ANN, namely the Paraconsistent Artificial Neural Network - PANN, which is capable of handling uncertain, inconsistent and paracomplete information. An architecture is presented to serve as an auxiliary method in diagnosing Alzheimer disease. Conclusions: We believe the results show PANN to be a promising tool to handle EEG analysis, bearing in mind two considerations: the growing interest of experts in visual analysis of EEG, and the ability of PANN to deal directly with imprecise, inconsistent, and paracomplete data, thereby providing a valuable quantitative analysis.
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Пархомов, Владимир, Vladimir Parhomov, Наталия Бородкова, Natalia Borodkova, Александр Яхнин, Aleksandr Yahnin, Райта Теро, et al. "Magnetospheric response of two types in PSc geomagnetic pulsations to interaction with interplanetary shock waves." Solar-Terrestrial Physics 4, no. 3 (September 28, 2018): 52–66. http://dx.doi.org/10.12737/stp-43201808.
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Using the June 22, 2015 event as an example, we present new data confirming the presence of a precursor of the sudden magnetic impulse caused by a powerful interplanetary shock wave (ISW). The precursor in the form of a train of oscillations (broadband pulse) with a falling frequency in the range 0.25÷11 Hz with a duration of ~20 s, which had a spectral resonance structure, was recorded globally by a network of induction magnetometers at 18:33:27 UT. No significant phase delays of the signals were detected in four frequency bands at widely spaced observatories. It is suggested that the impulse can be excited in the Earth – ionosphere waveguide by a pulsed electric field which occurs in the ionosphere due to the short-term impact of ISW on the magnetosphere.
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Janusas, Pilkauskas, Janusas, and Palevicius. "Active PZT Composite Microfluidic Channel for Bioparticle Manipulation." Sensors 19, no. 9 (April 29, 2019): 2020. http://dx.doi.org/10.3390/s19092020.
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The concept of active microchannel for precise manipulation of particles in biomedicine is reported in this paper. A novel vibration-assisted thermal imprint method is proposed for effective formation of a microchannel network in the nanocomposite piezo polymer layer. In this method, bulk acoustic waves of different wavelengths excited in an imprinted microstructure enable it to function in trapping–patterning, valve, or free particle passing modes. Acoustic waves are excited using a special pattern of electrodes formed on its top surface and a single electric ground electrode formed on the bottom surface. To develop the microchannel, we first started with lead zirconate titanate (PZT) nanopowder [Pb (Zrx, Ti1–x) O3] synthesis. The PZT was further mixed with three different binding materials—polyvinyl butyral (PVB), poly(methyl methacrylate) (PMMA), and polystyrene (PS)—in benzyl alcohol to prepare a screen-printing paste. Then, using conventional screen printing techniques, three types of PZT coatings on copper foil substrates were obtained. To improve the voltage characteristics, the coatings were polarized. Their structural and chemical composition was analyzed using scanning electron microscope (SEM), while the mechanical and electrical characteristics were determined using the COMSOL Multiphysics model with experimentally obtained parameters of periodic response of the layered copper foil structure. The hydrophobic properties of the PZT composite were analyzed by measuring the contact angle between the distilled water drop and the three different polymer composites: PZT with PVB, PZT with PMMA, and PZT with PS. Finally, the behavior of the microchannel formed in the nanocomposite piezo polymer was simulated by applying electrical excitation signal on the pattern of electrodes and then analyzed experimentally using holographic interferometry. Wave-shaped vibration forms of the microchannel were obtained, thereby enabling particle manipulation.
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Werner, S. M., C. J. Rodger, and N. R. Thomson. "Identifying power line harmonic radiation from an electrical network." Annales Geophysicae 23, no. 6 (September 15, 2005): 2107–16. http://dx.doi.org/10.5194/angeo-23-2107-2005.
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Abstract. It has been suggested that the space environment is being polluted by power line harmonic radiation (PLHR), generated from harmonics of the electrical power transmission frequency (50 or 60 Hz) and radiated into the ionosphere and magnetosphere by long power lines. While some in-situ satellite measurements of PLHR have been reported, it has proved difficult to confirm the source and overall significance. The electricity network of the city of Dunedin, New Zealand, is tiny compared to the many large industrial zones found outside New Zealand. However, the 1050Hz ripple control signal injected into the local electrical grid at regular intervals as a load-control mechanism provides an opportunity for identifying PLHR strengths radiated from a spatially well defined electrical network. In-situ observations by satellites should allow a greater understanding of PLHR and its significance as man-made pollution to near-Earth space. Calculations have been undertaken to estimate the strength of the radiation fields expected from the ripple control signal which is injected into the Dunedin city electrical network. We find that ground-based measurements will not be sensitive enough for detection of the ripple control radiation fields, even during the quietest winter night. While significant power penetrates the lower ionosphere, this is well below the reported threshold required for nonlinear triggering in the Van Allen radiation belts. Some radiated fields at satellite altitudes should be detectable, allowing in-situ measurements. At the altitude of the DEMETER mission, the radiated electric fields will not be detectable under any ionospheric conditions. However, we find that the radiated magnetic fields may be detectable by the DEMETER satellite at certain times, although this will be very difficult. Nonetheless, there is the possibility for future experimental campaigns. Keywords. Magnetospheric physics (Magnetosphereionosphere interactions; Plasma waves and instabilities) – Ionosphere (Active experiments)
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Karampatea, Apostolia, and Katherine Siakavara. "Analysis and Synthesis of Double Negative Dielectric Media Rectenna Systems for Ambient Microwave Energy Harvesting." International Journal of Antennas and Propagation 2018 (2018): 1–13. http://dx.doi.org/10.1155/2018/2472738.
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The concept of harvesting the ambient electromagnetic radiation energy, coming from public telecommunication wireless networks, has been recently subject of extensive research. Techniques proposed for this target use mainly antennas, as the grade gathering the radiation power. In this work, a method introducing the usage of specific dielectric structures with artificially negative electric permittivity and magnetic permeability (double negative media or DNG) in combination with wire dipole antenna sensors is proposed as an RF harvesting system. Theoretical study of the synthesized DNG medium’s performance and the distribution of the electromagnetic field in its interior is made, with the intention of finding the areas of maximum electric field intensity at which the antenna sensors would be positioned for maximum power scavenging. The received numerical results show that the synthesized schemes are capable of enhancing the energy gathering ability. Compared to the same antenna sensors positioned in free space, they ensure higher input voltage to the rectifier and also an increase of the available power about 10 dB. Moreover, they exhibit this performance for every direction of arrival of the incoming waves. The hybrid schemes DNG dipole antenna were designed for the Universal Mobile Telecommunication System (UMTS) frequency band, but the method is general and would be applied to any other frequency band and also with other antenna types.
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Sakai, J. I., R. Minamizuka, T. Kawata, and N. F. Cramer. "Nonlinear Torsional and Compressional Waves in a Magnetic Flux Tube with Electric Current near the Quiet Solar Photospheric Network." Astrophysical Journal 550, no. 2 (April 2001): 1075–92. http://dx.doi.org/10.1086/319802.
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Ahmad, Rais, and Tribikram Kundu. "Structural Health Monitoring of Steel Pipes under Different Boundary Conditions and Choice of Signal Processing Techniques." Advances in Civil Engineering 2012 (2012): 1–14. http://dx.doi.org/10.1155/2012/813281.
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Guided wave technique is an efficient method for monitoring structural integrity by detecting and forecasting possible damages in distributed pipe networks. Efficient detection depends on appropriate selection of guided wave modes as well as signal processing techniques. Fourier analysis and wavelet analysis are two popular signal processing techniques that provide a flexible set of tools for solving various fundamental problems in science and engineering. In this paper, effective ways of using Fourier and Wavelet analyses on guided wave signals for detecting defects in steel pipes are discussed for different boundary conditions. This research investigates the effectiveness of Fourier transforms and Wavelet analysis in detecting defects in steel pipes. Cylindrical Guided waves are generated by piezo-electric transducers and propagated through the pipe wall boundaries in a pitch-catch system. Fourier transforms of received signals give information regarding the propagating guided wave modes which helps in detecting defects by selecting appropriate modes that are affected by the presence of defects. Continuous wavelet coefficients are found to be sensitive to defects. Several types of mother wavelet functions such as Daubechies, Symlet, and Meyer have been used for the continuous wavelet transform to investigate the most suitable wavelet function for defect detection. This research also investigates the effect of different boundary conditions on wavelet transforms for different mother wavelet functions.
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Tian, Hao, Zijian Zhou, and Yu Sui. "Modeling and Validation of an Electrohydraulic Power Take-Off System for a Portable Wave Energy Convertor with Compressed Energy Storage." Energies 12, no. 17 (September 2, 2019): 3378. http://dx.doi.org/10.3390/en12173378.
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Small-scale, portable generation of electricity from ocean waves provides a versatile solution to power the ocean sensors network, in addition to the traditional large-scale wave energy conversion facilities. However, one issue of small-scale wave energy convertor (WEC) is the low capturable power density, challenging the design of the efficient power take-off (PTO) system. To tackle this challenge, in this paper, an electrohydraulic PTO system with compressed energy storage was proposed to boost output power of a portable WEC. Lumped-parameter kinematics and dynamics of the four-bar mechanism, the fluid dynamics of the digital fluid power circuit, and the mechanical and volumetric power losses were modeled and experimentally validated. Initial test results of the 0.64 m2 footprint prototype showed that the inclusion of storage improved the averaged electric power output over 40 times compared to the traditional architecture, and the proposed device can deliver up to 122 W at peaks.
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Пархомов, Владимир, Vladimir Parhomov, Наталия Бородкова, Natalia Borodkova, Александр Яхнин, Aleksandr Yahnin, Райта Теро, et al. "Magnetospheric response of two types in PSc geomagnetic pulsations to interaction with interplanetary shock waves." Solnechno-Zemnaya Fizika 4, no. 3 (September 28, 2018): 68–83. http://dx.doi.org/10.12737/szf-43201808.
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Using the June 22, 2015 event as an example, we present new data confirming the presence of a precursor of the sudden magnetic impulse caused by a powerful interplanetary shock wave (ISW). The precursor in the form of a train of oscillations (broadband pulse) with a falling frequency in the range 0.25÷11 Hz with a duration of ~20 s, which had a spectral resonance structure, was recorded globally by a network of induc-tion magnetometers at 18:33:27 UT. No significant phase delays of the signals were detected in four fre-quency bands at widely spaced observatories. It is sug-gested that the impulse can be excited in the Earth — ionosphere waveguide by a pulsed electric field which occurs in the ionosphere due to the short-term impact of ISW on the magnetosphere.
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Deng, Peng-cheng, Lin Li, and Chao Li. "Study on vibration of mistuned bladed disk with bi-periodic piezoelectric network." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 231, no. 2 (August 6, 2016): 350–63. http://dx.doi.org/10.1177/0954410016636916.
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The paper deals with the vibration suppression of a bladed disk structure with a piezoelectric network. The piezoelectric network without inductors has a different period (so-called bi-period) from that of the bladed disk. The research focuses on reducing amplified response or localized vibration, a phenomenon existing in bladed disks and induced by mistuning. The study is based on an electromechanical and cyclic-periodic lumped parameter model with two degrees of freedom per sector. Both mechanical mistuning and electrical mistuning have been taken into account. The modified modal assurance criterion is adopted to evaluate the ability of bi-periodic piezoelectric networks for suppressing vibration. The Monte Carlo simulation is used to calculate the modified modal assurance criterion of the system with random mistuning. To validate the numerical results, an experiment research is also carried out. In order to perform a comparison between numerical results and experimental results, the method of equivalent blisk model is introduced to identify the lumped parameters of the experimental model. In the experiment, traveling wave excitations are simulated as dynamical loads to excite the resonant vibration of coupling bladed disks in a rotating state. The results show that with a good design, the bi-periodic piezoelectric network can effectively suppress the amplified-forced-response due to the mistuning of the system, even though there are less piezoelectric patches and electric elements in the system compared to the system with piezoelectric shunt circuits.
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Rehman, Ali, Zeeshan Najam Khan, Muhammad Siddique, Muhammad Shahzad, Makhdoom Muhammad Naeem, and Majid Hussain. "An Artificial Intelligence Based Current Measurement Technique in High Voltage Power Transmission and Distribution Lines using Pyro-Sensors." Pakistan Journal of Engineering and Technology 4, no. 2 (June 28, 2021): 94–99. http://dx.doi.org/10.51846/vol4iss2pp94-99.
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High voltage transmission lines are the fundamental element in order to transfer electricity from the power plant/grid to consumers. The frequency, current and voltage are the key figures to sustain the absolute quality of the power transmission, and maintaining such high performance requires smart solutions and equipment like Current Transformer (CT) & Potential Transformer (PT). This proposed work enlightens an inception to monitor current in the high voltage transmission lines by using pyro-sensors, machine learning (ML) techniques and artificial intelligence (AI). Using pyro-sensors around the transmission/distribution lines, data will be gathered about the heat waves (infrared waves) generated by the electric current in the transmission/distribution line. The proposed methodology uses this data to be processed by neural network based artificial intelligent algorithm to evaluate the amount of current in the transmission line. The claim about the authenticity of the proposed technique is tested and verified by MATLAB simulation neural network toolbox.
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Choi, Sun-Seob, and Whi-Young Kim. "TRANSCRANIAL MAGNETIC STIMULATION WITH APPLIED MULTISTEP DIRECT CURRENT GRAFTING." Biomedical Engineering: Applications, Basis and Communications 25, no. 03 (May 30, 2013): 1350032. http://dx.doi.org/10.4015/s1016237213500324.
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The controlling method for high-voltage pulse form or pulse parameter is extremely important in high speed switching technique. Function generation can repeatedly make various forms and widths of pulse waves such as low-voltage sine wave, square wave, and sawtooth wave. Waveform control is not easy when voltage exceeds a certain amount of kVs. Pulse forming network (PFN) or pulse forming line (PFL) has been used so far along with trigger gap, rail gap, semiconductor switch, ignitron, cyratron, and autocompression switch, which are used as switching device. For PFN, multistep LC circuit is introduced to widen the pulse width, and for PFL, a method to lengthen the charging line is adopted. These methods are difficult to control because a large number of devices are used, and the devices are getting bigger in terms of size. In order to compensate this weakness, the researchers of this study made self-stimulating pulse forms with various pulse widths by actively engrafting the low-voltage two-step or four-step circuits with the AVR one-chip microprocessor technology, which is widely used for two-step or four-step electric network recently with low price.
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Li, Tansheng, Kikuzo Sawada, Harutoshi Ogai, and Wa Si. "UHF-Band Wireless Power Transfer System for Structural Health Monitoring Sensor Network." Smart Materials Research 2013 (November 11, 2013): 1–7. http://dx.doi.org/10.1155/2013/496492.
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For detecting and measuring health conditions of bridges, wireless sensor networks are used in these days. However, battery life is critically restricting the application and maintenance cost of sensor network systems. To extend life time, a wireless power transfer system at UHF band is introduced to supply the current wireless sensor network. This power transfer system is based on electric wave at 950 MHz. This power transfer system is redesigned for tiny power transmission, including a combination of a rectenna and a Cockcroft-Walton boost converter, battery board, and a control board. Also, current wireless sensor network is redesigned for power transfer system. The working flow of sensor network is modified to bottom-to-top to save power of sensor modules which are the power bottleneck of this sensor system. As a result, the system is able to support a sensor module continuously with received power of −14 dBmW, when the transmitting antenna is 30 dBmW at 10 meters distance.
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Fan, Zuwei, Rangtong Liu, and Xiaojie Cheng. "Preparation and Characterization of Electromagnetic Shielding Composites Based on Graphene-Nanosheets-Loaded Nonwoven Fabric." Coatings 11, no. 4 (April 6, 2021): 424. http://dx.doi.org/10.3390/coatings11040424.
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A fabric-like electromagnetic (EM) shielding composite based on nonwoven was fabricated using a coating method with a mixture containing graphene (GE) nanosheets and polyvinylidene fluoride (PVDF) adhesive agent, and then characterized for its mechanical properties, air permeability, EM properties, and morphologies. The GE loading amount and EM shielding effect was improved by applying a double coating process, with, in particular, a 2-sided coating that produced superior air permeability and shielding effectiveness (SE) than 2-layer coating. The coating produced an increased tensile initial modulus and flexural rigidity, whose increase was affected by the coating agent GE content. Increased GE content also resulted in decreased air permeability and increased SE and electrical conductivity. After coating with 25 g/L GE, the composite SE reached 31.2 dB, such that the electric/magnetic field strength of transmitted EM waves were reduced by ~97%. Scanning electron microscope and energy dispersive spectrometry results illustrated that aggregated GE was tightly bonded with the fibers due to the adhesive effect of PVDF and, with the increased coating agent GE content, the fibrous network was gradually filled with GE/PVDF attachments and increasing numbers of fibers were covered. Such an EM shielding material could be referenced for development by industrial or household protective applications.
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Jacobson, A. R., R. H. Holzworth, R. F. Pfaff, and M. P. McCarthy. "Study of oblique whistlers in the low-latitude ionosphere, jointly with the C/NOFS satellite and the World-Wide Lightning Location Network." Annales Geophysicae 29, no. 5 (May 18, 2011): 851–63. http://dx.doi.org/10.5194/angeo-29-851-2011.
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Abstract. We use the C/NOFS satellite's Vector Electric Field Instrument (VEFI) to study the relationship of impulsive electron whistlers in the low-latitude ionosphere to lightning strokes located by the World-Wide Lightning Location Network (WWLLN). In order to systematize this work, we develop an automated algorithm for recognizing and selecting the signatures of electron whistlers amongst many Very Low Frequency (VLF) recordings provided by VEFI. We demonstrate the application of this whistler-detection algorithm to data mining of a ~ two-year archive of VEFI recordings. It is shown that the relatively simple oblique electron whistler adequately accounts of the great majority of low-latitude oscillatory VLF waves seen in this study.
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Qin, Huixin, Jun Ma, Guodong Ren, and Ping Zhou. "Field coupling-induced wave propagation and pattern stability in a two-layer neuronal network under noise." International Journal of Modern Physics B 32, no. 27 (October 30, 2018): 1850298. http://dx.doi.org/10.1142/s0217979218502983.
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Synapse coupling is critical for information encoding of neurons. The effect of electromagnetic induction in cell becomes distinct when the exchange of charged ions across membrane is frequently triggered by external electric field or synapse current from adjacent neurons. In this paper, Gaussian white noise is imposed on a two-layer network composed of neurons with electromagnetic induction. The gap junction coupling is applied to connect the adjacent neurons and external stimulus with diversity is applied to keep different excitabilities of neurons in each layer. Neurons on the second layer are activated and modulated by using field coupling rather than channel coupling. It is found that the pattern formation on the network is much dependent on the initial setting due to the memory effect based on induction current via memristive synapse. Furthermore, field coupling intensity (D0) and noise intensity (D1) are changed to detect the development of spiral waves, target waves on the network in presence of noise. It confirms that noise can be helpful for pattern selection and synchronization approach on the two-layer network under field coupling, while field coupling can suppress the self-organization for pattern formation.
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LI, Ya Liang, Fei Zhao, and Zhi Rui Liang. "Modeling Simulation of Single-Phase Arc Grounding in Neutral Un-Effectual Grounding Power System Based on Matlab." Applied Mechanics and Materials 602-605 (August 2014): 3017–20. http://dx.doi.org/10.4028/www.scientific.net/amm.602-605.3017.
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Generally in China, the power distribution networks below 35kV level are Neutral un-effectual grounding systems. Single-phase electric arc grounding failure takes up the majority of neutral un-effectual grounding power system failures. However, it is a very complex process to deal with arc fault so that establishing a mathematical model for arc becomes challenging. Matlab Simulink was hence utilized to establish arc simulation model. Comparisons were made between the ideal wave form and the result based on the single phase arc grounding fault simulation to test the validity of the model, which shows good consistency.
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Bourriez, F., J. A. Sauvaud, J. L. Pinçon, J. J. Berthelier, and M. Parrot. "A statistical study over Europe of the relative locations of lightning and associated energetic burst of electrons from the radiation belt." Annales Geophysicae 34, no. 1 (February 1, 2016): 157–64. http://dx.doi.org/10.5194/angeo-34-157-2016.
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Abstract. The DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) spacecraft detects short bursts of lightning-induced electron precipitation (LEP) simultaneously with newly injected upgoing whistlers. The LEP occurs within < 1 s of the causative lightning discharge. First in situ observations of the size and location of the region affected by the LEP precipitation are presented on the basis of a statistical study made over Europe using the DEMETER energetic particle detector, wave electric field experiment, and networks of lightning detection (Météorage, the UK Met Office Arrival Time Difference network (ATDnet), and the World Wide Lightning Location Network (WWLLN)). The LEP is shown to occur significantly north of the initial lightning and extends over some 1000 km on each side of the longitude of the lightning. In agreement with models of electron interaction with obliquely propagating lightning-generated whistlers, the distance from the LEP to the lightning decreases as lightning proceed to higher latitudes.
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Kirihara, Soshu, Mitsuo Wada Takeda, Kazuaki Sakoda, Katsuya Honda, and Yoshinari Miyamoto. "Strong Localization of Electromagnetic Wave in Ceramic/Epoxy Photonic Fractals with Menger-Sponge Structure." Materials Science Forum 512 (April 2006): 227–32. http://dx.doi.org/10.4028/www.scientific.net/msf.512.227.
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Menger-sponge is a three dimensional fractal structure with self-similar patterns. We fabricated the Menger-sponge structure composed of epoxy with titania-based ceramic particles dispersion by using a stereolithography CAD/CAM system. It has a cubic body of 27 mm in edge size with square through holes of 1, 3 and 9 mm. The structure is characterized with a fractal dimension D = 2.73 and a fractal stage 3. The electromagnetic wave response of the Menger-sponge was measured by using a network analyzer. Both reflection and transmission amplitudes of incident waves showed remarkable attenuations to -50 dB at 8 GHz simultaneously. The electric field intensity in the center holes in the Menger-sponge was measured by using a mono-pole antenna. The electromagnetic energy was localized in the central air cavity by forming the strong localization mode. The localized mode frequency can be controlled by changing the structure size, number of stage, and the effective dielectric constant. We call such fractal structures as the photonic fractal.
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Chen, Zhongsheng, Jing He, and Gang Wang. "Vibration Bandgaps of Piezoelectric Metamaterial Plate with Local Resonators for Vibration Energy Harvesting." Shock and Vibration 2019 (June 24, 2019): 1–15. http://dx.doi.org/10.1155/2019/1397123.
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Embedded wireless sensing networks (WSNs) provide effective solutions for structural health monitoring (SHM), where how to provide long-term electric power is a bottle-neck problem. Piezoelectric vibration energy harvesting (PVEH) has been widely studied to realize self-powered WSNs due to piezoelectric effect. Structural vibrations are usually variable and exist in the form of elastic waves, so cantilever-like harvesters are not appropriate. In this paper, one kind of two-dimensional (2D) piezoelectric metamaterial plates with local resonators (PMP-LR) is investigated for structural vibration energy harvesting. In order to achieve low-frequency and broadband PVEH in SHM, it is highly necessary to study dynamic characteristics of PMP-LR, particularly bandgaps. Firstly, an analytical model is developed based on the Kirchhoff plate theory, and modal analysis is done by using the Rayleigh–Ritz method. Then, effects of geometric and material parameters on vibration bandgaps are analyzed by finite element-based simulations. In the end, experiments are carried out to validate the simulated results. The results demonstrate that the location of bandgaps can be easily adjusted by the design of local resonators. Therefore, the proposed method will provide an effective tool for optimizing local resonators in PMP-LR.
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Yamamoto, M., S. Fukao, R. T. Tsunoda, R. Pfaff, and H. Hayakawa. "SEEK-2 (Sporadic-<i>E</i> Experiment over Kyushu 2) − Project Outline, and Significance." Annales Geophysicae 23, no. 7 (October 13, 2005): 2295–305. http://dx.doi.org/10.5194/angeo-23-2295-2005.
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Abstract. SEEK-2 (Sporadic-E Experiment over Kyushu 2) is an observation campaign to study the spatial structure of the field-aligned irregularity (FAI) and sporadic-E(Es)-layer by means of two sounding rockets and a ground-based observation network with radars and optical instruments. The experiment was successfully conducted on 3 August 2002, with successive launches of two sounding rockets from the Uchinoura Space Center (USC) of the Japan Aerospace Exploration Agency (JAXA). The timing of the experiment was carefully selected, while intense quasi-periodic (QP) echoes were observed with two radars in Tanegashima. The main Es-layer, with its double-layered structure, was observed at altitudes of 103–105 km, the presence of which was well accounted for by the ion accumulation due to neutral-wind shear. Several minor peaks were detected in the electron density profiles at altitudes of up to 130 km. The intensity of the electric field was 5–10 mV/m and showed intense fluctuations below 110 km. Wave-like variation of the electric field was seen above 110 km. From radar experiments, we found that QP echoes appeared around 105 km, which agreed well with the main Es-layer height. The QP echoes propagated to the west-northwest, with frontal structures elongated from north-northeast to south-southwest. Radar observations conduced throughout the SEEK-2 period, on the other hand, showed that frontal structures of the QP echoes were most frequently propagated to the southeast. This result was consistent with the direction of gravity-wave propagation observed with the OH imager during the same period. The rocket beacon experiment with the Es-layers revealed the spatial structure of the plasma densities. On the basis of these results and those from SEEK-1 in 1996, we examined the structures of the nighttime mid-latitude E-region. We concluded that the QP echoes reflect the horizontal structures of the main Es-layers. The source of the structures was not clearly determined from the experiments, but the candidates are gravity waves and the Kelvin-Helmholtz instability. The azimuth-dependent Es-instability may have contributed to enhance structures of the QP echoes, although this instability may not be a major source of the QP structure in SEEK-2. Polarization electric fields were induced from the Es-layer with QP echoes, mapped upward along the geomagnetic field, and played an important role in determining the structures of the whole ionospheric E-region. Keywords. Mid-latitude ionosphere – Ionospheric irregularities – Ionosphere-atmosphere interactions
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Lytaev, Mikhail, Eugene Borisov, and Andrei Vladyko. "V2I Propagation Loss Predictions in Simplified Urban Environment: A Two-Way Parabolic Equation Approach." Electronics 9, no. 12 (November 27, 2020): 2011. http://dx.doi.org/10.3390/electronics9122011.
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This study is devoted to radio wave propagation modeling in the urban environment. Special attention has been paid to the features of vehicular ad hoc networks (VANETs) and vehicle-to-infrastructure (V2I) communications. For the first time, the three-dimensional bidirectional parabolic equation (PE) method has been applied to the specified problem. Buildings and other obstacles are modeled by impenetrable (perfectly electric conducting) cuboids. A harmonic radiation source with an arbitrary direction pattern may be modeled. Numerical simulation is performed for various propagation scenarios. A comparison with the ray-tracing (RT) method is given. The results of the numerical simulation prove the effectiveness and reliability of the proposed method. Some recommendations for deploying VANETs are obtained based on the numerical results.
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Jones, David. "Electric waves." Nature 416, no. 6877 (March 2002): 140. http://dx.doi.org/10.1038/416140a.
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Jung, Seungmin, Jihoon Moon, Sungwoo Park, and Eenjun Hwang. "An Attention-Based Multilayer GRU Model for Multistep-Ahead Short-Term Load Forecasting." Sensors 21, no. 5 (February 26, 2021): 1639. http://dx.doi.org/10.3390/s21051639.
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Recently, multistep-ahead prediction has attracted much attention in electric load forecasting because it can deal with sudden changes in power consumption caused by various events such as fire and heat wave for a day from the present time. On the other hand, recurrent neural networks (RNNs), including long short-term memory and gated recurrent unit (GRU) networks, can reflect the previous point well to predict the current point. Due to this property, they have been widely used for multistep-ahead prediction. The GRU model is simple and easy to implement; however, its prediction performance is limited because it considers all input variables equally. In this paper, we propose a short-term load forecasting model using an attention based GRU to focus more on the crucial variables and demonstrate that this can achieve significant performance improvements, especially when the input sequence of RNN is long. Through extensive experiments, we show that the proposed model outperforms other recent multistep-ahead prediction models in the building-level power consumption forecasting.
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Kelebekler, Ersoy. "Investigation of the Leaky-Wave Characteristics of a Cylindrical Dielectric Rod Using the Coefficient Matrix of the System of Characteristic Equations and Davidenko’s Method." Journal of Electromagnetic Engineering and Science 21, no. 3 (July 31, 2021): 189–200. http://dx.doi.org/10.26866/jees.2021.3.r.26.
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An open dielectric waveguide includes both guided propagating modes within the waveguide and radiating and evanescent modes that propagate transversely outside the waveguide. In this study, the leaky-wave characteristics of a cylindrical dielectric rod are investigated using the coefficient matrix of the system of characteristic equations and Davidenko’s method. Using the coefficient matrix of the system of characteristic equations simplified the derivative(s) required to use Davidenko’s method. The results obtained for a 10-mm radius structure with a relative dielectric constant of 4 showed that a second antenna mode region existed for higher-order hybrid HE modes and lower-order transverse magnetic (TM) modes. However, it did not exist for transverse electric (TE) modes. Additionally, the hybrid HE modes had larger leaky-wave spectrum and antenna mode regions than both the TE and TM modes. This demonstrates that for antenna applications, hybrid HE modes supply a wider frequency spectrum.
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Bollig, Michael. "The colonial encapsulation of the north-western Namibian pastoral economy." Africa 68, no. 4 (October 1998): 506–36. http://dx.doi.org/10.2307/1161164.
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The inhabitants of Kaokoland, Himba and Herero, have recently gained prominence in the discussions concerning a controversial hydro-electric power scheme in their region. They are depicted as southern Africa's ‘most traditional pastoralists’ by groups opposing the dam and those demanding it. The article describes how Kaokoland's pastoralists suffered tremendously from the politics of encapsulation the South African government adopted against them. Having been enmeshed in interregional trade networks, commodity production and wage labour around 1900, they were isolated by the South African government within a period of twenty years. Buffer zones for the commercial ranching area and prohibitions on movement across other newly invented boundaries limited their spatial mobility. Trade across borders was inhibited altogether. Pastoralists who had diversified their assets during the previous fifty years and had taken the chance of a first wave of commercial penetration were forced back on to subsistence herding.
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Cresta, Massimo, Fabio Massimo Gatta, Alberto Geri, Marco Maccioni, and Marco Paulucci. "Resilience Assessment in Distribution Grids: A Complete Simulation Model." Energies 14, no. 14 (July 16, 2021): 4303. http://dx.doi.org/10.3390/en14144303.
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For several years, the increase of extreme meteorological events due to climate change, especially in unusual areas, has focused authorities and stakeholders attention on electric power systems' resilience. In this context, the authors have developed a simulation model for managing the resilience of electricity distribution grids with respect to the main threats to which these infrastructures may be exposed (i.e., ice sleeves, heat waves, water bombs, floods, tree falls). The simulator identifies the more vulnerable network assets by means of probabilistic indexes, thus suggesting the best corrective actions to be implemented for resilience improvement. The fulfillment of grid constraints, i.e., loading limits for branches and voltage limits for buses, under actual operating conditions, is taken into account. Load scenarios extracted from available measurements are evaluated by means of load flow analyses in order to choose, among the best solutions identified, those compatible with the constraints. The proposed tool can assist Distribution System Operators (DSOs) in drawing up the Action Plan to improve, on one hand, the resilience of the network and, on the other hand, to remove any possible limitation for the adoption of the best solutions to ensure maximum operational continuity during extreme weather events.
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Farooq, Shaik Mullapathi, S. M. Suhail Hussain, Siddavaram Kiran, and Taha Selim Ustun. "Certificate Based Security Mechanisms in Vehicular Ad-Hoc Networks based on IEC 61850 and IEEE WAVE Standards." Electronics 8, no. 1 (January 15, 2019): 96. http://dx.doi.org/10.3390/electronics8010096.
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When equipped with an on-board wireless kit, electric vehicles (EVs) can communicate with nearby entities, e.g., road side units (RSUs), via a vehicle ad-hoc network (VANET). More observability enables smart charging algorithms where charging stations (CSs) are allocated to EVs based on their current state of charge, destination, and urgency to charge. IEEE 1609 WAVE standard regulates VANETs, while IEC 61850 is emerging as the smart grid communication standard. In order to integrate these two domains of energy management, past research has focused on harmonizing these two standards for a full smart city solution. However, this solution requires very sensitive data to be transmitted, such as ownership of EV, owners’ personal details, and driving history. Therefore, data security in these networks is of prime concern and needs to be addressed. In this paper, different security mechanisms defined by the IEEE 1609 WAVE standard are applied for both vehicle-to-infrastructure (V2I) and vehicle-to-grid (V2G) communication. The former relates to EV–RSU, while the latter covers EV–CS communication. The implicit and explicit certificate mechanism processes proposed in IEEE 1609 WAVE for authentication are studied in great detail. Furthermore, a performance evaluation for these mechanisms is presented in terms of total time lapse for authentication, considering both the computational time and communication time delays. These results are very important in understanding the extra latency introduced by security mechanisms. Considering that VANETs may be volatile and may disappear as EVs drive away, overall timing performance becomes vital for operation. Reported results show the magnitude of this impact and compare different security mechanisms. These can be utilized to further develop VANET security approaches based on available time and the required security level.
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Sakli, Hedi. "Cylindrical Waveguide on Ferrite Substrate Controlled by Externally Applied Magnetic Field." Electronics 10, no. 4 (February 17, 2021): 474. http://dx.doi.org/10.3390/electronics10040474.
Full textAbstract:
This paper presents an extension of the formulation of wave propagation in transverse electric (TE) and transverse magnetic (TM) modes for the case of metallic cylindrical waveguides filled with longitudinally magnetized ferrite. The higher order modes were exploited. We externally controlled the cut-off frequency through the application of DC magnetic fields. The numerical results of dispersion diagrams for TE and TM modes were obtained and analyzed. We analyzed a waveguide antenna filled with partially magnetized ferrite using the mode matching (MM) technique based on the TE and TM modes. By using modal analysis, our approach considerably reduced the computation time compared to HFSS. Ferrites are important for various industrial applications, such as circulators, isolators, antennas and filters.