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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 (March 27, 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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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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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 (April 1, 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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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 (April 29, 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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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 (August 30, 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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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 (October 28, 2011): 1621–31. http://dx.doi.org/10.1080/15325008.2011.608768.
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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 (December 1, 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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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 (January 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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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 (November 7, 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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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 (February 17, 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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Toader, Dumitru, Marian Greconici, Daniela Vesa, Maria Vintan, Claudiu Solea, Adrian Maghet, and Ildiko Tatai. "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 (August 7, 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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Billeke, Pablo, Tomas Ossandon, Marcela Perrone-Bertolotti, Philippe Kahane, Julien Bastin, Karim Jerbi, Jean-Philippe Lachaux, and Pablo Fuentealba. "Human Anterior Insula Encodes Performance Feedback and Relays Prediction Error to the Medial Prefrontal Cortex." Cerebral Cortex 30, no. 7 (February 28, 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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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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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 (December 17, 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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Gadalińska, Elżbieta, Andrzej Baczmański, Sebastian Wroński, Mirosław Wróbel, Alain Lodini, Vincent Klosek, and Christian Scheffzük. "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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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 (May 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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Azouri, Assaf, Volker Roeber, Martin David Guiles, Melissa Iwamoto, Tara Owens, Janet Becker, and Douglas S. Luther. "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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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 (July 1, 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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Nájera, Jorge, Hugo Mendonça, Rosa de Castro, and Jaime Arribas. "Strategies Comparison for Voltage Unbalance Mitigation in LV Distribution Networks Using EV Chargers." Electronics 8, no. 3 (March 5, 2019): 289. http://dx.doi.org/10.3390/electronics8030289.
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The increasing penetration of Electric Vehicles (EVs) in LV distribution networks can potentially cause voltage quality issues such as voltage unbalance and under-voltage conditions. According to the EV charger characteristics, some strategies can be adopted to mitigate the aforementioned effects. Smart decentralized charging controls seem to be a more practical solution than centralized controls, since there is no need for communication because they rely only on local measurements. The four most relevant decentralized charging strategies, two for single-phase and two for three-phase EV chargers, have been implemented in a typical three-phase four-wire European LV distribution network. Simulations have been carried out for scenarios with single-phase EV chargers, three-phase EV chargers, and a combination of both. Single-phase controls are aimed at under-voltage regulation, while three-phase controls are focused on mitigating voltage unbalance. Results show that the implementation of a decentralized EV charging control is an adequate solution for Distribution System Operators (DSOs) since it improves the reliability and security of the network. Moreover, even though decentralized charging control does not use any communication, the combination of three-phase and single-phase controls is able to mitigate voltage unbalance while preventing the under-voltage condition.
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SHETH, AMIT P., SUNIT K. GALA, and SHAMKANT B. NAVATHE. "ON AUTOMATIC REASONING FOR SCHEMA INTEGRATION." International Journal of Cooperative Information Systems 02, no. 01 (March 1993): 23–50. http://dx.doi.org/10.1142/s0218215793000034.
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Success in database schema integration depends on the ability to capture real world semantics of the schema objects, and to reason about the semantics. Earlier schema integration approaches mainly rely on heuristics and human reasoning. In this paper, we discuss an approach to automate a significant part of the schema integration process. Our approach consists of three phases. An attribute hierarchy is generated in the first phase. This involves identifying relationships (equality, disjointness and inclusion) among attributes. We discuss a strategy based on user-specified semantic clustering. In the second phase, a classification algorithm based on the semantics of class subsumption is applied to the class definitions and the attribute hierarchy to automatically generate a class taxonomy. This class taxonomy represents a partially integrated schema. In the third phase, the user may employ a set of well-defined comparison operators in conjunction with a set of restructuring operators, to further modify the schema. These operators as well as the automatic reasoning during the second phase are based on subsumption. The formal semantics and automatic reasoning utilized in the second phase is based on a terminological logic as adapted in the CANDIDE data model. Classes are completely defined in terms of attributes and constraints. Our observation is that the inability to completely define attributes and thus completely capture their real world semantics imposes a fundamental limitation on the possibility of automatically reasoning about attribute definitions. This necessitates human reasoning during the first phase of the integration approach.
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Alzueta, Elisabet, Massimiliano de Zambotti, Teji Dulai, Benedetta Albinni, Katharine Simon, Negin Sattari, Jing Zhang, Sara Mednick, and Fiona Baker. "259 Tracking naturalistic sleep over the menstrual cycle with a wearable in healthy young women." Sleep 44, Supplement_2 (May 1, 2021): A104. http://dx.doi.org/10.1093/sleep/zsab072.258.
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Abstract Introduction A woman’s menstrual cycle is characterized by hormonal changes that might affect sleep and therefore daily functionality. While some studies using self-reports have shown a lower sleep quality in the peri-menstruation phase, objective – in lab – studies have not found significant differences in sleep continuity during the menstrual cycle, but are limited by only a few recordings across the cycle. The aim of this study is to examine changes in sleep during the healthy menstrual cycle using a multi-sensory wearable, allowing continuous, objective, reliable and ecologically valid measurement. Methods 12 healthy young women (28.14 ± 2.33) were monitored using Oura ring – a sleep and activity tracker – during an entire menstrual cycle. Participants also reported mood, readiness, and sleep quality using a diary. Four phases of the menstrual cycle were compared (menstruation, periovulation, mid-luteal, and late-luteal). Ovulation day was determined using a urinary luteinizing hormone test. Results Ovulatory cycles were confirmed by the Oura ring, which showed a significant increase in average nocturnal heart rate and skin temperature during the post-ovulatory luteal phase relative to menstruation and periovulation. Oura ring measures of sleep continuity (Sleep Onset Latency, Wake After Sleep Onset) and self-reported sleep quality did not change across the 4 menstrual phases. We observed a trend for objective sleep duration, which tended to be shorter in the mid-luteal and late-luteal phases. We also observed a small reduction in perceived readiness and mood during these two phases. Conclusion Physiological changes (increase in heart rate and body temperature) in the postovulatory phase of the menstrual cycle are detectable with the Oura ring. Sleep features remain quite stable during the healthy, ovulatory menstrual cycle, apart from a trend for slightly shorter sleep duration in the post-ovulatory phases. In comparison to self-reports, which rely on retrospective memory and might be biased by perception and mood, wearable technologies seem to be a sensitive and informative tool to track sleep and physiological changes during the menstrual cycle. Support (if any) Supported by RF1AG061355 (Baker/Mednick)
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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 (October 1, 2020): 39. http://dx.doi.org/10.11591/ijeecs.v20.i1.pp39-45.
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<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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Camut, Julia, Ignacio Barber Rodriguez, Hasbuna Kamila, Aidan Cowley, Reinhard Sottong, Eckhard Mueller, and Johannes de Boor. "Insight on the Interplay between Synthesis Conditions and Thermoelectric Properties of α-MgAgSb." Materials 12, no. 11 (June 7, 2019): 1857. http://dx.doi.org/10.3390/ma12111857.
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α-MgAgSb is a very promising thermoelectric material with excellent thermoelectric properties between room temperature and 300 °C, a range where few other thermoelectric materials show good performance. Previous reports rely on a two-step ball-milling process and/or time-consuming annealing. Aiming for a faster and scalable fabrication route, herein, we investigated other potential synthesis routes and their impact on the thermoelectric properties of α-MgAgSb. We started from a gas-atomized MgAg precursor and employed ball-milling only in the final mixing step. Direct comparison of high energy ball-milling and planetary ball-milling revealed that high energy ball milling already induced formation of MgAgSb, while planetary ball milling did not. This had a strong impact on the microstructure and secondary phase fraction, resulting in superior performance of the high energy ball milling route with an attractive average thermoelectric figure of merit of z T avg = 0.9. We also show that the formation of undesired secondary phases cannot be avoided by a modification of the sintering temperature after planetary ball milling, and discuss the influence of commonly observed secondary phases on the carrier mobility and on the thermoelectric properties of α-MgAgSb.
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André, Alain A. M., and Evan Spruijt. "Liquid–Liquid Phase Separation in Crowded Environments." International Journal of Molecular Sciences 21, no. 16 (August 17, 2020): 5908. http://dx.doi.org/10.3390/ijms21165908.
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Biomolecular condensates play a key role in organizing cellular fluids such as the cytoplasm and nucleoplasm. Most of these non-membranous organelles show liquid-like properties both in cells and when studied in vitro through liquid–liquid phase separation (LLPS) of purified proteins. In general, LLPS of proteins is known to be sensitive to variations in pH, temperature and ionic strength, but the role of crowding remains underappreciated. Several decades of research have shown that macromolecular crowding can have profound effects on protein interactions, folding and aggregation, and it must, by extension, also impact LLPS. However, the precise role of crowding in LLPS is far from trivial, as most condensate components have a disordered nature and exhibit multiple weak attractive interactions. Here, we discuss which factors determine the scope of LLPS in crowded environments, and we review the evidence for the impact of macromolecular crowding on phase boundaries, partitioning behavior and condensate properties. Based on a comparison of both in vivo and in vitro LLPS studies, we propose that phase separation in cells does not solely rely on attractive interactions, but shows important similarities to segregative phase separation.
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Grigonyte, Aurelija M., Christian Harrison, Paul R. MacDonald, Ariadna Montero-Blay, Matthew Tridgett, John Duncan, Antonia P. Sagona, Chrystala Constantinidou, Alfonso Jaramillo, and Andrew Millard. "Comparison of CRISPR and Marker-Based Methods for the Engineering of Phage T7." Viruses 12, no. 2 (February 10, 2020): 193. http://dx.doi.org/10.3390/v12020193.
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With the recent rise in interest in using lytic bacteriophages as therapeutic agents, there is an urgent requirement to understand their fundamental biology to enable the engineering of their genomes. Current methods of phage engineering rely on homologous recombination, followed by a system of selection to identify recombinant phages. For bacteriophage T7, the host genes cmk or trxA have been used as a selection mechanism along with both type I and II CRISPR systems to select against wild-type phage and enrich for the desired mutant. Here, we systematically compare all three systems; we show that the use of marker-based selection is the most efficient method and we use this to generate multiple T7 tail fibre mutants. Furthermore, we found the type II CRISPR-Cas system is easier to use and generally more efficient than a type I system in the engineering of phage T7. These results provide a foundation for the future, more efficient engineering of bacteriophage T7.
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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 (February 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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Mandallaz, Daniel, and Alexander Massey. "Comparison of estimators in one-phase two-stage Poisson sampling in forest inventories." Canadian Journal of Forest Research 42, no. 10 (October 2012): 1865–71. http://dx.doi.org/10.1139/x2012-110.
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In the context of Poisson sampling, numerous adjustments to classical estimators have been proposed that are intended to compensate for inflated variance due to random sample size. However, such adjustments have never been applied to extensive forest inventories. This work investigates the performances of four estimators for the timber volume in one-phase two-stage forest inventories, where trees in the first stage are selected, at the plot level, by concentric circles or angle-count methods and a subset thereof are selected by Poisson sampling for further measurements to get a better estimation. The original two-stage estimator is the sum of two components: the first is the mean of Horwitz–Thompson estimators using simple volume approximations, based on diameter and species alone, of all first-stage trees in each inventory plot, and the second is the mean of Horwitz–Thompson estimators based on the differences between the simple volume approximations and refined volume determinations based on further diameter and height measurements on the second-stage trees within each inventory plot. This two-stage estimator is particularly useful because it provides unbiased estimates even if the simple prediction model is not correct, which is particularly important for small area estimation. The other three estimators rely on adjustments of the second component of the original estimator that are adapted from estimators proposed in the literature by L.R. Grosenbaugh and C.-E. Särndal. It turns out that these adjustments introduce a negligible bias and that the original simple estimator performs just as well or even better than the new estimators with respect to the variance.
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Despot, Daneish, Micaela Pacheco Fernández, and Matthias Barjenbruch. "Comparison of Online Sensors for Liquid Phase Hydrogen Sulphide Monitoring in Sewer Systems." Water 13, no. 13 (July 5, 2021): 1876. http://dx.doi.org/10.3390/w13131876.
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Hydrogen sulfide (H2S) related to wastewater in sewer systems is known for causing significant problems of corrosion and odor nuisance. Sewer systems severely affected by H2S typically rely on online H2S gas sensors for monitoring and control. However, these H2S gas sensors only provide information about the H2S emission potential at the point being monitored, which is sometimes inadequate to design control measures. In this study, a comparison of three market-ready online sensors capable of liquid-phase H2S detection in sewer systems was assessed and compared. Two of the three sensors are based on UV/Vis spectrophotometry, while the other adapted the design and principles of a Clark-type electrochemical microsensor. The H2S measurements of the sensors were statistically compared to a standard laboratory method at first. Following that, the performance of the online sensors was evaluated under realistic sewer conditions using the Berlin Water Company (BWB) research sewer pilot plant. Test applications representing scenarios of typical H2S concentrations found in sulfide-affected sewers and during control measures were simulated. The UV/Vis spectrometers showed that the performance of the sensors was highly dependent on the calibration type and measurements used for deriving the calibration function. The electrochemical sensor showed high sensitivity by responding to alternating anaerobic/anoxic conditions simulated during nitrate dosing. All sensors were prone to measurement disturbances due to high amounts of sanitary solids in wastewater at the study site and required continuous maintenance for reliable measurements. Finally, a summary of the key attributes and limitations of the sensors compared for liquid phase H2S detection is outlined.
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Sommariva, Alessandro, and Stefano Zucca. "A Comparison between Two Reduction Strategies for Shrouded Bladed Disks." Applied Sciences 8, no. 10 (September 26, 2018): 1736. http://dx.doi.org/10.3390/app8101736.
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Shrouded bladed disks exhibit a nonlinear dynamic behavior due to the contact interfaces at shrouds between neighboring blades. As a result, reduced order models (ROMs) are mandatory to compute the response levels during the design phase for high cycle fatigue (HCF) life assessment. In this paper, two reduction strategies for shrouded bladed disk reduction are presented. Both approaches rely on: (i) the cyclic symmetry of the linear bladed disk with open shrouds to perform only single sector calculations, (ii) the Craig–Bampton (CB) method to reduce the number of physical degrees of freedom (dofs). The two approaches are applied to a set of test cases in order to evaluate and compare their accuracy and the associated computational effort. Although both approaches allow for generating accurate ROMs, it is found that the numerical efficiency of the two methods depends on the ratio of the number of nodes at the inter-sector interfaces over the number of inner nodes of the elementary sector model.
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Hanson, Jordan C. "Broadband RF Phased Array Design with MEEP: Comparisons to Array Theory in Two and Three Dimensions." Electronics 10, no. 4 (February 8, 2021): 415. http://dx.doi.org/10.3390/electronics10040415.
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Phased array radar systems have a wide variety of applications in engineering and physics research. Phased array design usually requires numerical modeling with expensive commercial computational packages. Using the open-source MIT Electrogmagnetic Equation Propagation (MEEP) package, a set of phased array designs is presented. Specifically, one and two-dimensional arrays of Yagi-Uda and horn antennas were modeled in the bandwidth [0.1–5] GHz, and compared to theoretical expectations in the far-field. Precise matches between MEEP simulation and radiation pattern predictions at different frequencies and beam angles are demonstrated. Given that the computations match the theory, the effect of embedding a phased array within a medium of varying index of refraction is then computed. Understanding the effect of varying index on phased arrays is critical for proposed ultra-high energy neutrino observatories which rely on phased array detectors embedded in natural ice. Future work will develop the phased array concepts with parallel MEEP, in order to increase the detail, complexity, and speed of the computations.
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Perryman, M. A. C. "Assessment of the Quality of the IDT Elemental Observations." Highlights of Astronomy 9 (1992): 414. http://dx.doi.org/10.1017/s1539299600009345.
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AbstractThe quasi-simultaneous measurement of the one-dimensional angular separation of stars on the sky, on both small and large angular scales, rely on the measurements made by the IDT detector, as well as on inputs from the star mapper and attitude control system. This presentation will concentrate on the results of a comparison of the results of the IDT data processing carried out by the FAST and NDAC data analysis teams. The extent to which the intensity and phase measurements agree between the two reductions, and the extent to which the differences are consistent with expected photon noise errors, will be illustrated.
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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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Fisher, Jill A., Torin Monahan, and Rebecca L. Walker. "Picking and Choosing Among Phase I Trials." Journal of Bioethical Inquiry 16, no. 4 (November 12, 2019): 535–49. http://dx.doi.org/10.1007/s11673-019-09946-w.
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Abstract This article empirically examines how healthy volunteers evaluate and make sense of the risks of phase I clinical drug trials. This is an ethically important topic because healthy volunteers are exposed to risk but can gain no medical benefit from their trial participation. Based on in-depth qualitative interviews with 178 healthy volunteers enrolled in various clinical trials, we found that participants focus on myriad characteristics of clinical trials when assessing risk and making enrolment decisions. These factors include the short-term and long-term effects; required medical procedures; the type of trial, including its design, therapeutic area of investigation, and dosage of the drug; the amount of compensation; and trust in the research clinic. In making determinations about the study risks, participants rely on information provided during the consent process, their own and others’ experiences in clinical trials, and comparisons among studies. Our findings indicate that the informed consent process succeeds in communicating well about certain types of risk information while simultaneously creating lacunae that are problematically filled by participants through their collective experiences and assumptions about risk. We discuss the ethical implications of these findings and make recommendations for improving the consent process in healthy volunteer trials.
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Chen, Der-Fa, Yi-Cheng Shih, Shih-Cheng Li, Chin-Tung Chen, and Jung-Chu Ting. "Mixed Modified Recurring Rogers-Szego Polynomials Neural Network Control with Mended Grey Wolf Optimization Applied in SIM Expelling System." Mathematics 8, no. 5 (May 9, 2020): 754. http://dx.doi.org/10.3390/math8050754.
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Due to a good ability of learning for nonlinear uncertainties, a mixed modified recurring Rogers-Szego polynomials neural network (MMRRSPNN) control with mended grey wolf optimization (MGWO) by using two linear adjusted factors is proposed to the six-phase induction motor (SIM) expelling continuously variable transmission (CVT) organized system for acquiring better control performance. The control system can execute MRRSPNN control with a fitted learning rule, and repay control with an evaluated rule. In the light of the Lyapunov stability theorem, the fitted learning rule in the MRRSPNN control can be derived, and the evaluated rule of the repay control can be originated. Besides, the MGWO by using two linear adjusted factors yields two changeable learning rates for two parameters to find two ideal values and to speed-up convergence of weights. Experimental results in comparisons with some control systems are demonstrated to confirm that the proposed control system can achieve better control performance.
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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 (April 1, 2020): 251. http://dx.doi.org/10.11591/ijeecs.v18.i1.pp251-260.
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<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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Walker, S. N., and I. Moiseenko. "Determination of wave vectors using the phase differencing method." Annales Geophysicae 31, no. 9 (September 27, 2013): 1611–17. http://dx.doi.org/10.5194/angeo-31-1611-2013.
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Abstract. Due to the collisionless nature of space plasmas, plasma waves play an important role in the redistribution of energy between the various particle populations in many regions of geospace. In order to fully comprehend such mechanisms it is necessary to characterise the nature of the waves present. This involves the determination of properties such as wave vector k. There are a number of methods used to calculate k based on the multipoint measurements that are now available. These methods rely on the fact that the same wave packet is simultaneously observed at two or more locations whose separation is small in comparison to the correlation length of the wave packet. This limitation restricts the analysis to low frequency (MHD) waves. In this paper we propose an extension to the phase differencing method to enable the correlation of measurements that were not made simultaneously but differ temporally by a number of wave periods. The method is illustrated using measurements of magnetosonic waves from the Cluster STAFF search coil magnetometer. It is shown that it is possible to identify wave packets whose coherence length is much less than the separation between the measurement locations. The resulting dispersion is found to agree with theoretical results.
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Scudder, Jillian M., Sara L. Ellison, Loubna El Meddah El Idrissi, and Henry Poetrodjojo. "Conversions between gas-phase metallicities in MaNGA." Monthly Notices of the Royal Astronomical Society 507, no. 2 (August 13, 2021): 2468–87. http://dx.doi.org/10.1093/mnras/stab2339.
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ABSTRACT We present polynomial conversions between each of 11 different strong line gas-phase metallicity calibrations, each based on ∼1.1 million star-forming spaxels in the public Sloan Digital Sky Survey (SDSS) Data Release 15 (DR15) Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey. For this sample, which is ∼20 times larger than previous works, we present fifth-order polynomial fits for each of 110 possible calibration conversions, for both Small Magellanic Cloud-type and Milky Way-type dust corrections. The typical 2σ scatter around our polynomial fits is 0.1 dex; we present the range over which the metallicities are valid. Conversions between metallicities which rely on the same set of line ratios, or a heavily shared set of emission lines, have reduced scatter in their conversions relative to those conversions with little overlap in required emission lines. Calibration conversions with less consistent sets of emission lines also have increased galaxy-to-galaxy variability, and this variability can account for up to 35 per cent of the total scatter. We also compare our conversions to previous work with the single fibre SDSS DR7 spectra along with higher spatial resolution data from the TYPHOON Integral Field Spectroscopy survey, resulting in comparison samples with spatial resolutions from several kpc down to ∼100 pc. Our metallicity conversions, obtained with the large sample of MaNGA, are robust against the influence of diffuse ionized gas, redshift, effective radius, and spatial blurring, and are therefore consistent across both integrated spectra and the high-resolution integral field spectroscopy data.
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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 (July 7, 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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Pirlog, Alina-Maria, Cristian Daniel Pirlog, and Marius Adrian Maghiar. "DOACs vs Vitamin K Antagonists: a Comparison of Phase III Clinical Trials and a Prescriber Support Tool." Open Access Macedonian Journal of Medical Sciences 7, no. 7 (April 13, 2019): 1226–32. http://dx.doi.org/10.3889/oamjms.2019.289.
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AIM: The purpose of this article was to systematically review the literature assessing the efficacy and safety of phase III clinical trials for each direct oral anticoagulant versus vitamin K antagonists and to design a ’’go-to’’ table for the prescriber.
MATERIAL AND METHODS: A systematic review of specialist literature was conducted to identify RCTs which compared direct oral anticoagulants (DOACs) with standard warfarin treatment. Medline, Em-base, and the Cochrane databases were searched from January 2005- January 2019. The inclusion criteria were randomised controlled trials of oral anticoagulants in patients with non-valvular atrial fibrillation (NVAF). Four publications were phase III randomised control trials (RCTs) included in the final analysis.
RESULTS: Regarding the primary outcome in RELY the results were 1.69% per 100-year patients (p/y) for Warfarin compared to 1.11% p/y dabigatran etexilate 150mg BD (twice daily). In ROCKET AF the rates of the primary outcome were 2.2% p/y for warfarin compared to 1.7% p/y for rivaroxaban 20 mg OD (once daily). In ARISTOTLE trial the rates of the primary outcome were 1.60% p/y for warfarin compared to 1.27% p/y for apixaban 5 mg BD. In ENGAGE AF TIMI, the rates of the primary outcome were 1.50% p/y for warfarin compared to 1.18% p/y for edoxaban 60mg BD.
CONCLUSION: DOACs showed to be either noninferior or superior to warfarin with regards to the primary outcome with better safety patterns. Our ’’go-to’’ table provides a supportive tool for physicians in preventing medical errors when managing patients on oral anticoagulants.
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Mohd Yusoff, Ahmad Huzaifah, Midhat Nabil Ahmad Salimi, and Mohd Faizal Jamlos. "A New XRD Method to Quantitatively Distinguish Non-Stoichiometric Magnetite: Influence of Particle Size and Processing Conditions." Advanced Engineering Forum 26 (February 2018): 41–52. http://dx.doi.org/10.4028/www.scientific.net/aef.26.41.
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Magnetite’s abilities rely on the quantitative phases present in the sample. Magnetite quality can strongly influence several physical properties, such as magnetism, catalytic performance, and Verwey transition. However, differentiation of magnetite and maghemite through the conventional X-ray diffractogram comparison are not relevant for the intermediate phases. In this study, the deviation from the ideal stoichiometric magnetite and the relative quantification of both phases were mathematically achievable through a new XRD technique. Various synthesis conditions were applied to obtain different crystallite sizes, in the range of 9 to 30 nm. Generally, the stoichiometric deviation and maghemite content would be significantly influenced by the final size, whereas system conditions (temperature of solution, agitation rate, and pH of solution) would only have minor significance. In this study, iron oxide nanoparticles prepared using the co-precipitation method was calculated to contain 100% magnetite for particles of 30.26 nm in size, while 100% maghemite was calculated for particles at 9.64 nm.
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Rael, Michael, Agnes Benedict, Jack Ishak, Sarah Cadarette, Marco Campioni, and Sumeet Panjabi. "Indirect Comparisons to Assess the Relative Efficacy of Carfilzomib + Lenalidomide + Dexamethasone Versus Panobinostat + Bortezomib + Dexamethasone and Bortezomib + Dexamethasone: A Matching Adjusted Indirect Comparison." Blood 126, no. 23 (December 3, 2015): 5622. http://dx.doi.org/10.1182/blood.v126.23.5622.5622.
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Abstract Background: Several novel treatments have recently been approved for the treatment of relapsed multiple myeloma (RMM). In the absence of head-to-head comparisons between these novel treatments, clinicians and payers must rely on statistical indirect comparisons. The objective of this analysis is to derive measures of relative effectiveness for carfilzomib + lenalidomide + dexamethasone (KRd) against bortezomib + dexamethasone (Vd), and the recently approved combination of panobinostat + bortezomib + dexamethasone (PVd) in patients with RMM who have been treated with at least one prior therapy. Methods: A matching-adjusted indirect comparison (MAIC) (Signorovitch, 2010) for progression-free survival (PFS) and overall survival (OS) was conducted between the KRd arm of the phase III study ASPIRE (Stewart et al., 2015) versus the PVd and Vd arms of the phase III study PANORAMA 1 (San-Miguel et al., 2014). The MAIC utilized patient level data from ASPIRE, and adjusted for reported patient population differences. An MAIC uses a propensity score type equation to assign case weights to the KRd patients so that their weighted baseline characteristics match the baseline of the PVd or Vd population. This re-weighting process attempts to answer the question: What would the outcomes be if KRd had been administered to a population matching the characteristics of the PVd or Vd arms? Adjustments were made for age, gender, ECOG status, history of autologous stem cell transplant, disease duration, number of prior regimens, ISS stage, prior bortezomib use, and creatinine clearance rate. Cox PH models were fitted to estimate hazard ratios (HRs) for PFS and OS. Weibull survival curves best fit the adjusted survival data and were used to estimate median survival times. A simulated treatment comparison (STC) (Ishak et al., 2015), which adjusts for reported patient population differences using regression equations, was conducted as a cross validation. Results: The KRd arm in ASPIRE included 396 patients and the PVd and Vd arms in PANORAMA 1 included 387 and 381 patients, respectively. After successfully matching, the effective sample size of the KRd population was 131 for the PVd comparison and 138 for the Vd comparison. See Figure 1 for the MAIC adjusted PFS and OS Kaplan-Meier curves. Hazard ratios (95% CIs) from the Cox models for PFS and OS outcomes were 0.317 (0.228, 0.44) and 0.582 (0.394, 0.86) for KRd vs PVd, respectively and 0.208 (0.153, 0.283) and 0.472 (0.324, 0.688) for KRd vs Vd, respectively. Corresponding hazard ratios from the STC were similar and validate the MAIC results. Estimates of median PFS and OS in months were 29.5 and 65.2 for KRd compared to 12.0 and 40.9 for PVd, respectively. Corresponding estimates were 29.7 and 57.3 for KRd compared to 8.2 and 33.0 for Vd. Figure 1. Conclusion: This MAIC analysis suggests that KRd provides a consistent and statistically significant PFS and OS benefit relative to PVd and Vd in RMM patients who have been treated with at least one prior therapy. Beyond the patient characteristics available from PANORAMA 1, other variables that may potentially influence outcomes were not adjusted for in the analysis. This analysis did not compare KRd to PVd in patients who have received at least 2 prior regimens including bortezmib and an IMiD (panobinostat's FDA-approved indication) due to lack of published data on the baseline characteristics of this patient subset studied in PANORAMA 1. Disclosures Rael: Onyx: Consultancy; Evidera: Employment. Benedict:Onyx: Consultancy; Evidera: Employment. Ishak:Onyx: Consultancy; Evidera: Employment. Cadarette:Evidera: Employment; Onyx: Consultancy. Campioni:Amgen: Employment, Equity Ownership. Panjabi:Onyx Pharmaceuticals Inc., An Amgen Subsidiary: Employment, Equity Ownership.
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Kokhanovsky, A. A., J. L. Deuzé, D. J. Diner, O. Dubovik, F. Ducos, C. Emde, M. J. Garay, et al. "The inter-comparison of major satellite aerosol retrieval algorithms using simulated intensity and polarization characteristics of reflected light." Atmospheric Measurement Techniques 3, no. 4 (July 15, 2010): 909–32. http://dx.doi.org/10.5194/amt-3-909-2010.
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Abstract. Remote sensing of aerosol from space is a challenging and typically underdetermined retrieval task, requiring many assumptions to be made with respect to the aerosol and surface models. Therefore, the quality of a priori information plays a central role in any retrieval process (apart from the cloud screening procedure and the forward radiative transfer model, which to be most accurate should include the treatment of light polarization and molecular-aerosol coupling). In this paper the performance of various algorithms with respect to the of spectral aerosol optical thickness determination from optical spaceborne measurements is studied. The algorithms are based on various types of measurements (spectral, angular, polarization, or some combination of these). It is confirmed that multiangular spectropolarimetric measurements provide more powerful constraints compared to spectral intensity measurements alone, particularly those acquired at a single view angle and which rely on a priori assumptions regarding the particle phase function in the retrieval process.
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Kokhanovsky, A. A., J. L. Deuzé, D. J. Diner, O. Dubovik, F. Ducos, C. Emde, M. J. Garay, et al. "The inter-comparison of major satellite aerosol retrieval algorithms using simulated intensity and polarization characteristics of reflected light." Atmospheric Measurement Techniques Discussions 2, no. 6 (December 22, 2009): 3369–439. http://dx.doi.org/10.5194/amtd-2-3369-2009.
Full textAbstract:
Abstract. Remote sensing of aerosol from space is a challenging and typically underdetermined retrieval task, requiring many assumptions to be made with respect to the aerosol and surface models. Therefore, the quality of a priori information plays a central role in any retrieval process (apart from the cloud screening procedure and the forward radiative transfer model, which to be most accurate should include the treatment of light polarization and molecular-aerosol coupling). In this paper the performance of various algorithms with respect to the of spectral aerosol optical thickness determination from optical spaceborne measurements is studied. The algorithms are based on various types of measurements (spectral, angular, polarization, or some combination of these). It is confirmed that multiangular spectropolarimetric measurements provide more powerful constraints compared to spectral intensity measurements alone, particularly those acquired at a single view angle and which rely on a priori assumptions regarding the particle phase function in the retrieval process.
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Csatár, János, and András Dán. "Neutral Voltage Comparison of Different Grounding Configurations and Calculation Methods in Multi-Grounded Low Voltage Network." Periodica Polytechnica Electrical Engineering and Computer Science 61, no. 1 (February 10, 2017): 77. http://dx.doi.org/10.3311/ppee.10379.
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The steady growth in distributed generation brings more and more attention to low voltage (LV) distribution networks. Therefore, a good model is important to study these trends, especially with local regulation. Grounding the neutral line at multiple points along the network is a common practice in many European countries influencing neutral currents and voltages. Modelling grounding current had been of little interest at network planning and operation before, with only passive consumers. However, with the growing number of smart equipment, it becomes an overlooked, yet important issue. This equipment usually rely on local measurements and regulates accordingly. Given that most of the LV equipment uses single-phase connection, the neutral voltage is an important issue. Yet few papers study the neutral line behaviour and often overlook the effect of grounding. This article studies the effect of different grounding configurations on neutral voltages, and compares it with one of the most commonly used calculation method in literature that incorporates groundings. The differences are large enough to adversely affect local regulation.
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Becker, Thomas, Olaf Ziemann, Rainer Engelbrecht, and Bernhard Schmauss. "Optical Strain Measurement with Step-Index Polymer Optical Fiber Based on the Phase Measurement of an Intensity-Modulated Signal." Sensors 18, no. 7 (July 17, 2018): 2319. http://dx.doi.org/10.3390/s18072319.
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Polymer optical fibers (POFs) have been proposed for optical strain sensors due to their large elastic strain range compared to glass optical fibers (GOFs). The phase response of a single-mode polymer optical fiber (SM-POF) is well-known in the literature, and depends on the physical deformation of the fiber as well as the impact on the refractive index of the core. In this paper, we investigate the impact of strain on a step-index polymer optical fiber (SI-POF). In particular, we discuss the responsivity of an optical strain sensor which is based on the phase measurement of an intensity-modulated signal. In comparison to the phase response of an SM-POF, we must take additional influences into account. Firstly, the SI-POF is a multi-mode fiber (MMF). Consequently, we not only consider the strain dependence of the refractive index, but also its dependency on the propagation angle θz. Second, we investigate the phase of an intensity-modulated signal. The development of this modulation phase along the fiber is influenced by modal dispersion, scattering, and attenuation. The modulation phase therefore has no linear dependency on the length of the fiber, even in the unstrained state. For the proper consideration of these effects, we rely on a novel model for step-index multi-mode fibers (SI-MMFs). We expand the model to consider the strain-induced effects, simulate the strain responsivity of the sensor, and compare it to experimental results. This led to the conclusion that the scattering behavior of a SI-POF is strain-dependent, which was further proven by measuring the far field at the end of a SI-POF under different strain conditions.
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Klapilová Krbová, Petra. "Shopping Behaviour of Generation Y: A Comparison of Czech Republic and Slovakia." Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 64, no. 2 (2016): 617–26. http://dx.doi.org/10.11118/actaun201664020617.
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Study of Generation Y shopping behaviour was conducted in Czech Republic and Slovakia. The main aim was to describe the whole decision making process of this generational cohort. In this paper, only selected features are presented, especially early phases of decision making. For the purposes of the study, people with the year of birth between 1980 and 2000 served as a population. Data were collected by online and written questionnaire during autumn and winter 2014/2015. The sample of 380 respondents was conducted by non-probability sampling technique, more specifically judgemental sampling. Results suggest that Generation Y individuals prefer online environment to search for information before purchase. The four most used channels in both countries are the same and all online (e.g. web search engine or retailer’s website). These young people mainly rely on themselves when they look for some personal recommendations, so own experience was the most important source. The choice of a particular shop is influenced by the quality of goods offered, but also by the price level which should be below the competitors. Wide assortment which enables to choose an appropriate product is also preferred. According to these results segmentation in both countries was conducted. Particular segments in both countries differ, but we can also find some common attributes.
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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 (August 6, 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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Liu, Hongfei, Chanaka Jayawardhena, Victoria-Sophie Osburg, and Mujahid Mohiuddin Babu. "Do online reviews still matter post-purchase?" Internet Research 30, no. 1 (September 30, 2019): 109–39. http://dx.doi.org/10.1108/intr-07-2018-0331.
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Purpose The influence of electronic word-of-mouth (eWOM) information, such as online reviews, on consumers’ decision making is well documented, but it is unclear if online reviews still matter in post-purchase evaluation and behaviours. The purpose of this paper is to examine the extent to which online reviews (aggregate rating (AR) and individual reviews (IR)) influence consumers’ evaluation and post-purchase behaviour by considering the valence congruence of online reviews and consumption experience (CE). Design/methodology/approach Following social comparison theory and relevant literature, the authors conduct an online experiment (pre-test: n=180; main study: n=347). The authors rely on a 2 (CE valence) ×2 (AR valence) ×2 (IR valence) between-subjects design. Findings Congruence/incongruence between the valences of CE, AR and IR affects consumers’ post-purchase evaluation at the emotional, brand and media levels and review-writing behaviour. In comparison to aggregated rating, IR are more important in the post-purchase stage. Similarly, consumers have a higher eWOM-writing intention when there is congruence between the valences of CE, AR and IR. Practical implications The authors demonstrate the importance of service providers continually monitoring their business profiles on review sites to ensure consistency of review information, as these influence consumers’ post-purchase evaluation and behaviours. For this reason, the authors illustrate the utility of why media owners of review sites should support the monitoring process to facilitate the engagement of both businesses and customers. Originality/value The authors break new ground by empirically testing the impact of online review information post-purchase seen through the theoretical lens of social comparison. The approach is novel in breaking down and testing the dimensions of post-purchase evaluation and behavioural intentions in understanding the social comparison elicited by online reviews in the post-purchase phase.
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Karasiewicz-Szczypiorski, Radosław. "Roman fort at Cape Aj-Todor (Charax) and its surroundings. A new look at old discoveries." Światowit 57 (December 17, 2019): 153–84. http://dx.doi.org/10.5604/01.3001.0013.6813.
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Despite many years of research at the site, the Roman fort at Cape Aj-Todor near Yalta remains rela- tively poorly studied. A better understanding of the discoveries made at the site can be reached by comparing them with the results of the excavations conducted in another fort also located in Crimea – at BalaklavaKadykovka. This text is an attempt at gathering together all the published information about the discoveries made at Cape Aj-Todor. The comparison of the research results from both sites has enabled establishing numerous similarities between them. Both forts functioned simultaneously, and their architectural remains can be qualified to identically dated phases. The final effect of the analysis undertaken by the author is a more complete plan of the fort at Cape Aj-Todor along with its surroundings, processed in a new graphic formula.