Journal articles: 'Rippon Lea'

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Hamza, M. A., G. P. Riethmuller, and W. K. Anderson. "Experimental subsoiling by in-line shallow and deep tines." Soil Research 51, no. 6 (2013): 477. http://dx.doi.org/10.1071/sr13129.

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Conventional soil ripping has high fuel consumption because it involves high draft force and may produce large soil clods. This experiment compares the use of shallow leading tines ahead of the main tine with use of a conventional single-tine ripper. The study showed that attaching a single, shallow leading tine ahead of, and in line with, the main tine and 25–40% shallower in depth gave the greatest significant decrease in specific draft force. This led to a fuel reduction from 13.6 to 11.5 L/ha, or a saving of 15% when ripping a moist loamy sand soil to 330 mm depth. Attaching more than one shallow lead tine ahead of the ripper did not significantly affect specific draft forces, whether the shallow lead tines were in line or offset. Other advantages of using the shallow leading tine ripper over the conventional ripper are: improved soil tilth by significantly decreasing soil clod size; potentially a wider moisture range for ripping the soil (as soil clods are smaller and drier soil increases clod size) thus increasing the time available for the operation; and decreased depreciation of ripping components.

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Jannah, Roudlotul, Ari Murtono, and Siswoko Siswoko. "Desain dan Analisis Ripple Tegangan dan Arus Luaran Peralatan Baterai Lead Acid." Jurnal Elektronika dan Otomasi Industri 4, no. 3 (November 27, 2020): 33. http://dx.doi.org/10.33795/elkolind.v4i3.120.

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Proses pengisian baterai khususnya lead acidpasti akan timbul ripple tegangan dan arus pada keluaranoutputnya. Dalam penelitian ini, ripple dianalisa untukmelihat seberapa besar pengaruhnya terhadap proses pengisianaccu. Untuk menghasilkan ripple tegangan dan arus yangdiinginkan, pemakaian filter LC dalam topologi buck-boostconverter harus diatur dan dianalisa.Penelitian ripple initergantung dari pemakaian filter LC yang otomatis akanmenimbulkan rugi-rugi. Analisis penelitian ripple inidiperlihatkan melalui hasil percobaan.

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Ruck, Sebastian, Frederik Arbeiter, and Torben Petri. "Laser-Doppler-Anemometrie-Messungen in einem quadratischen Kanal mit eng beieinanderliegenden Rippen an einer Wand." tm - Technisches Messen 89, no. 3 (February 2, 2022): 158–67. http://dx.doi.org/10.1515/teme-2021-0121.

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Zusammenfassung In der vorliegenden Arbeit werden Ergebnisse von Laser-Doppler-Anemometrie (LDA)-Geschwindigkeitsmessungen in einem einseitig mit transversal orientierten Rippen-Rauheiten strukturierten quadratischen Kanal für die Strömung mit einer Reynolds-Zahl von Re H = 5 , 0 · 10 4 {\mathit{Re}_{H}}=5,0\cdot {10^{4}} vorgestellt. Das Rippenabstand-Rippenhöhe-Verhältnis war 3 und die Verblockungsrate betrug 6 , 7 % 6,7\hspace{0.1667em}\% . Es werden Verteilungen der mittleren Geschwindigkeiten, Reynolds-Spannungen sowie Triple-Geschwindigkeit-Korrelationen präsentiert. Die Ergebnisse zeigen die Entwicklung einer dreidimensionalen Sekundärströmung oberhalb der Rippen, wodurch sich ein schwach advektiver wandnormaler Fluidtransport zwischen der rippennahen Strömung und der Kanalkernströmung einstellt. Der Einfluss der Rippen-Rauheiten auf das turbulente Strömungsgeschehen und die einhergehenden turbulenten Austauschvorgänge ist jedoch auf die unmittelbare Rippennähe begrenzt. Die anhand der statistischen Momente höherer Ordnung beschriebenen rippeninduzierten instationären Strömungsvorgänge sowie der diffusive Transport treten oberhalb der Rippen nur in einem schmalen Band auf.

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Fernando Menke, Maikel, José Marcos Alonso Álvarez, Rodrigo V. Tambara, and Álysson Raniere Seidel. "HYBRID DUAL-LOOP CONTROL FOR CURRENT REGULATION AND LOW-FREQUENCY RIPPLE REJECTION IN LED DRIVERS." Eletrônica de Potência 26, no. 03 (September 8, 2021): 315–27. http://dx.doi.org/10.18618/rep.2021.3.0010.

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Sakong, Suk-Chin, Hyun-Seo Park, Jeong-Il Kang, and Sang-Kyoo Han. "Power Factor Correction LED Driver with Small 120Hz Current Ripple." Transactions of the Korean Institute of Power Electronics 19, no. 1 (February 20, 2014): 91–97. http://dx.doi.org/10.6113/tkpe.2014.19.1.91.

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Kang, Hyemin, Nazareno Donato, and Florin Udrea. "Effect of Pillar Ripple on Static and Dynamic Trade-Offs in Superjunction MOSFETs." IEEE Electron Device Letters 41, no. 5 (May 2020): 753–56. http://dx.doi.org/10.1109/led.2020.2985203.

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Chaturvedi, Shivam, Mengqi Wang, Yaoyu Fan, Deepak Fulwani, Guilherme Vieira Hollweg, Shahid Aziz Khan, and Wencong Su. "Control Methodologies to Mitigate and Regulate Second-Order Ripples in DC–AC Conversions and Microgrids: A Brief Review." Energies 16, no. 2 (January 10, 2023): 817. http://dx.doi.org/10.3390/en16020817.

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Second-order ripples occur in the voltage and current during any DC–AC power conversion. These conversions occur in the voltage source inverters (VSIs), current source inverters (CSIs), and various single-stage inverters (SSIs) topologies. The second-order ripples lead to oscillating source node currents and DC bus voltages when there is an interconnection between the AC and DC microgrids or when an AC load is connected to the DC bus of the microgrid. Second-order ripples have various detrimental effects on the sources and the battery storage. In the storage battery, they lead to the depletion of electrodes. They also lead to stress in the converter or inverter components. This may lead to the failure of a component and hence affect the reliability of the system. Furthermore, the second-order ripple currents (SRCs) lead to ripple torque in wind turbines and lead to mechanical stress. SRCs cause a rise in the temperature of photovoltaic panels. An increase in the temperature of PV panels leads to a reduction in the power generated. Furthermore, the second-order voltage and current oscillations lead to a varying maximum power point in PV panels. Hence, the maximum power may not be extracted from it. To mitigate SRCs, oversizing of the components is needed. To improve the lifespan of the sources, storage, and converter components, the SRCs must be mitigated or kept within the desired limits. In the literature, different methodologies have been proposed to mitigate and regulate these second-order ripple components. This manuscript presents a comprehensive review of different effects of second-order ripples on different sources and the methodologies adopted to mitigate the ripples. Different active power decoupling methodologies, virtual impedance-based methodologies, pulse width modulation-based signal injection methodologies, and control methods adopted in distributed power generation methods for DC microgrids have been presented. The application of ripple control methods spans from single converters such as SSIs and VSIs to a network of interconnected converters. Furthermore, different challenges in the field of virtual impedance control and ripple mitigation in distributed power generation environments are discussed. This paper brings a review regarding control methodologies to mitigate and regulate second-order ripples in DC–AC conversions and microgrids.

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Sarracino, Diego, Alice Garavaglia, Emanuela S. Gritti, Laura Parolin, and Marco Innamorati. "Dropout from cognitive behavioural treatment in a case of bulimia nervosa: The role of the therapeutic alliance." Research in Psychotherapy: Psychopathology, Process and Outcome 16, no. 2 (January 12, 2014): 71–84. http://dx.doi.org/10.4081/ripppo.2013.138.

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Despite the refinement of the cognitive treatment for eating disorders, relatively high dropout rates represent a major problem for therapists and researchers. This study investigated the case of a patient with a diagnosis of bulimia nervosa, who dropped out of outpatient CBT after 28 weekly sessions. In addition to standard clinical outcome assessment, we examined how patient's psychological functioning and therapeutic alliance changed across sessions by applying observer-rating scales to the therapy transcripts. Although the patient reported some improvement at the six-month retest, observer ratings showed persistence of impaired functioning and frequent ruptures in the patient-therapist relationship throughout the treatment. We concluded that a thorough examination of the therapy process might help to understand the factors that lead to premature treatment termination.

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Kwon, Min-Jun, and Woo-Cheol Lee. "A Study on the Control Technique of LLC Resonant Converter for LED Driver with 120Hz Ripple Current." Transactions of The Korean Institute of Electrical Engineers 68, no. 12 (December 31, 2019): 1557–65. http://dx.doi.org/10.5370/kiee.2019.68.12.1557.

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Wang, Songda, Danyang Bao, Gustavo Gontijo, Sanjay Chaudhary, and Remus Teodorescu. "Modeling and Mitigation Control of the Submodule-Capacitor Voltage Ripple of a Modular Multilevel Converter under Unbalanced Grid Conditions." Energies 14, no. 3 (January 28, 2021): 651. http://dx.doi.org/10.3390/en14030651.

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A modular multilevel converter’s (MMC’s) submodule (SM)-capacitor voltage will increase under unbalanced grid conditions. Depending on the imbalance level, the voltage ripple can be considerably high, and it can exceed the pre-defined safe limits. If this occurs, the converter will trip, which can lead to serious stability problems for the grid. This paper first proposes an analytical solution for deriving the three-phase imbalanced SM ripple of an MMC under an unbalanced grid. With this analytical tool, the imbalance mechanism of the SM voltage ripple can be easily understood. What is more, the symmetrical component method is first applied to analyze the three-phase SM capacitor ripple, and the positive-/negative-/zero-sequence components of the three-phase SM voltage ripple are easily identified by the proposed analytical method. Then, based on this powerful analytical tool, the proper circulating-current profile to be injected can be obtained, allowing for the right compensation of the voltage ripple. Based on this approach, two new voltage ripple compensation methods are proposed in this paper. Simulations were carried out to validate the analytical description of the submodule-capacitor voltage ripple proposed in this paper. Moreover, simulation and experimental results are provided to validate the new compensation techniques introduced in this paper.

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Altholz, Josef L., and John Powell. "Gladstone, Lord Ripon, and the Vatican Decrees, 1874." Albion 22, no. 3 (1990): 449–59. http://dx.doi.org/10.2307/4051181.

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In August 1874, the Marquess of Ripon, until recently a Liberal Cabinet Minister, decided to convert from the Church of England to that of Rome. The Times, which like the rest of the English political world assumed that this ended Ripon's public career, denounced the moral “obliquity” of the man who “has renounced his mental and moral freedom, and has submitted himself to the guidance of the Roman Catholic Priesthood.” In October, the former Prime Minister, William E. Gladstone, asserted in an article on ritualism that the High Church position could not lead to Rome because, among other things, “no one can become her convert without renouncing his moral and mental freedom and placing his civil loyalty and duty at the mercy of another.” Remonstrances from Catholics (among them Ripon) on the issue of civil loyalty led Gladstone to develop his position fully in a pamphlet in November, The Vatican Decrees in their Bearing on Civil Allegiance: A Political Expostulation, which in turn provoked one of the major Church-State controversies of the century. Historians have generally assumed that Ripon's conversion was causally connected with Gladstone's outburst.” It was, but with a difference.

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Korth Pereira Ferraz, Pablo, and Julia Kowal. "A Comparative Study on the Influence of DC/DC-Converter Induced High Frequency Current Ripple on Lithium-Ion Batteries." Sustainability 11, no. 21 (October 31, 2019): 6050. http://dx.doi.org/10.3390/su11216050.

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Modern battery energy systems are key enablers of the conversion of our energy and mobility sector towards renewability. Most of the time, their batteries are connected to power electronics that induce high frequency current ripple on the batteries that could lead to reinforced battery ageing. This study investigates the influence of high frequency current ripple on the ageing of commercially available, cylindrical 18,650 lithium-ion batteries in comparison to identical batteries that are aged with a conventional battery test system. The respective ageing tests that have been carried out to obtain numerous parameters such as the capacity loss, the gradient of voltage curves and impedance spectra are explained and evaluated to pinpoint how current ripple possibly affects battery ageing. Finally, the results suggest that there is little to no further influence of current ripple that is severe enough to stand out against ageing effects due to the underlying accelerated cyclic ageing.

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Knebel, Ellen, Gabby Cunningham, Grace Young, and Erika Woolsey. "How Immersive Experience and the Ripple Effect Lead to Sustainable Agreements." Academy of Management Proceedings 2019, no. 1 (August 1, 2019): 15143. http://dx.doi.org/10.5465/ambpp.2019.15143abstract.

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Santis Brand, Jean, Maicol Flores de Melo, José Marcos Alonso Álvarez, and Marco Antônio Dalla Costa. "ANALYSIS OF LOW-FREQUENCY RIPPLE TRANSMISSION TO DCM OPERATING CONVERTERS FOR LED DRIVERS." Eletrônica de Potência 25, no. 1 (March 31, 2020): 9–18. http://dx.doi.org/10.18618/rep.2020.1.0059.

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Teye, Alfred Larm, Michel Knoppel, Jan de Haan, and Marja G. Elsinga. "Amsterdam house price ripple effects in The Netherlands." Journal of European Real Estate Research 10, no. 3 (November 6, 2017): 331–45. http://dx.doi.org/10.1108/jerer-11-2016-0041.

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Purpose This paper aims to examine the existence of the ripple effect from Amsterdam to the housing markets of other regions in The Netherlands. It identifies which regional housing markets are influenced by house price movements in Amsterdam. Design/methodology/approach The paper considers the ripple effect as a lead-lag effect and a long-run convergence between the Amsterdam and regional house prices. Using the real house prices for second-hand owner-occupied dwellings from 1995q1 to 2016q2, the paper adopts the Toda–Yamamoto Granger Causality approach to study the lead-lag effects. It uses the autoregressive distributed lags (ARDL)-Bounds cointegration techniques to examine the long-run convergence between the regional and the Amsterdam house prices. The paper controls for house price fundamentals to eliminate possible confounding effects of common shocks. Findings The cumulative evidence suggests that Amsterdam house prices have influence on (or ripple to) all the Dutch regions, except one. In particular, the Granger Causality test concludes that a lead-lag effect of house prices exists from Amsterdam to all the regions, apart from Zeeland. The cointegration test shows evidence of a long-convergence between Amsterdam house prices and six regions: Friesland, Groningen, Limburg, Overijssel, Utrecht and Zuid-Holland. Research limitations/implications The paper adopts an econometric approach to examine the Amsterdam ripple effect. More sophisticated economic models that consider the asymmetric properties of house prices and the patterns of interregional socio-economic activities into the modelling approach are recommended for further investigation. Originality/value This paper focuses on The Netherlands for which the ripple effect has not yet been researched to the authors’ knowledge. Given the substantial wealth effects associated with house price changes that may shape economic activity through consumption, evidence for ripples may be helpful to policy makers for uncovering trends that have implications for the entire economy. Moreover, the analysis controls for common house price fundamentals which most previous papers ignored.

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Lukman, Grace Firsta, Xuan Son Nguyen, and Jin-Woo Ahn. "Design of a Low Torque Ripple Three-Phase SRM for Automotive Shift-by-Wire Actuator." Energies 13, no. 9 (May 7, 2020): 2329. http://dx.doi.org/10.3390/en13092329.

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The shift-by-wire (SBW) system in vehicles aims to increase performance, safety, and comfort during driving. Switched reluctance motors (SRMs) are simple, resilient, and require only minimum maintenance; these factors make it a good option for use as an SBW actuator. Inherently, SRM generates a higher torque ripple than other AC machines, which can lead to a deterioration of its function. In this paper, a non-uniform air-gap rotor structure combined with the careful positioning of holes near the pole surface is proposed to reduce the torque ripple. The finite element method (FEM) is employed to analyze the electromagnetic characteristics of the design. The proposed motor is manufactured, and experiments are done to verify the performance. The design alone can reduce the torque ripple by 7% and flatten the torque waveform. The experimental result shows that the proposed motor can achieve the desired performance. The estimated torque ripple from the experiment is 26.65%.

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Lee, Y. J., T. S. Liu, Mao-Hsing Lin, and Kun-Feng Huang. "Investigation of Liquid Crystal Ripple Using Ericksen-Leslie Theory for Displays Subject to Tactile Force." Mathematical Problems in Engineering 2013 (2013): 1–11. http://dx.doi.org/10.1155/2013/932492.

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Liquid crystal display panels subjected to tactile force will show ripple propagation on screens. Tactile forces change tilt angles of liquid crystal molecules and alter optical transmission so as to generate ripple on screens. Based on the Ericksen-Leslie theory, this study investigates ripple propagation by dealing with tilt angles of liquid crystal molecules. Tactile force effects are taken into account to derive the molecule equation of motion for liquid crystals. Analytical results show that viscosity, tactile force, the thickness of cell gap, and Leslie viscosity coefficient lead to tilt angle variation. Tilt angle variations of PAA liquid crystal molecules are sensitive to tactile force magnitudes, while those of 5CB and MBBA with larger viscosity are not. Analytical derivation is validated by numerical results.

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Liu, Jincheng, Jiguang Yue, Li Wang, Chenhao Wu, and Feng Lyu. "A Low-Cost, High-Precision Method for Ripple Voltage Measurement Using a DAC and Comparators." Electronics 8, no. 5 (May 27, 2019): 586. http://dx.doi.org/10.3390/electronics8050586.

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As the core of electronic system, the switched-mode power supply (SMPS) will lead to serious accidents and catastrophes if it suddenly fails. According to the related research, the monitoring of ripple can acquire the health degree of SMPS indirectly. To realize low-cost, high-precision, and automatic ripple measurement, this paper proposes a new ripple voltage (peak-to-peak value) measuring scheme, utilizing a DAC and two high-speed comparators. Within this scheme, the DC component of SMPS output is blocked by a high-pass filter (HPF). Then, the filtered signal and the reference voltage from a DAC together compose the input of a high-speed comparator. Finally, output pulses of the comparator are captured by a microcontroller unit (MCU), which readjusts the output of the DAC by calculation, and this process is repeated until the DAC output is exactly equal to the peak (or valley) value of ripple. Moreover, in order to accelerate the measurement process, a peak estimation method is specially designed to calculate the output ripple peak (or valley) value of buck topology through merely two measurements. Then the binary search method is utilized to obtain a more exact value on the basis of estimative results. Additionally, an analysis of the measurement error of this ripple measurement system is executed, which shows that the theoretical error is less than 0.5% where the ripple value is larger than 500 mV. Furthermore, appropriate components are selected, and a prototype is manufactured to verify the validity of the proposed theory.

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Blanche, J. G., and D. C. H. Yang. "Cycloid Drives With Machining Tolerances." Journal of Mechanisms, Transmissions, and Automation in Design 111, no. 3 (September 1, 1989): 337–44. http://dx.doi.org/10.1115/1.3259004.

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The cycloidal speed reducer, or cycloid drive, is an epicyclic gear train in which the profile of the planet gear is an epitrochoid and the annular sun gear has rollers as its teeth. The cycloid drive has very high efficiency and small size, in comparison with a conventional gear mechanism, making it an attractive candidate for limited space applications. On the other hand, in this type of transmissions there exist two major drawbacks, namely, backlash and torque ripple. Backlash, the angle through which the output shaft can rotate when the input shaft is held fixed, has a degrading effect on the output accuracy. Torque ripple, the variation in mechanical advantage as the input shaft rotates, causes vibrations and could lead to dynamic instability of the machinery. If the cycloid drive were manufactured to the ideal dimensions, there would be no backlash nor torque ripple. However, in reality, there will always be some machining tolerances. In this paper an analytical model is developed which models the cycloid drive with machining tolerances. Consequently, the effect of machining tolerances on backlash and torque ripple are investigated. It is found that both the backlash and the torque ripple are inherent periodic functions of the input crank angle.

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Griffin, M. J., and N. H. Macmillan. "Longitudinal and transverse ripple formation during the solid particle erosion of lead." Materials Science and Engineering 80, no. 1 (June 1986): L1—L4. http://dx.doi.org/10.1016/0025-5416(86)90307-1.

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Teston, Silvio Antonio, Kaio Vinicius Vilerá, Marcello Mezaroba, and Cassiano Rech. "Control System Development for the Three-Ports ANPC Converter." Energies 13, no. 15 (August 1, 2020): 3967. http://dx.doi.org/10.3390/en13153967.

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This paper proposes a control system for the single-phase Three-Ports Active Neutral- Point-Clamped (ANPC-3P) converter, which can inject a sinusoidal current into the grid, balance the neutral point voltage, and regulate the energy storage system (ESS) current with reduced low-frequency ripple. Despite other applications, ANPC-3P inverter can be used in grid-tied renewable generation to allow the simultaneous connection of a photovoltaic (PV) energy source and an ESS to the AC grid. The ESS is connected directly to the inverter circuit without any auxiliary DC-DC converter, but due to the DC bus pulsed power, it can be subjected to low-frequency current ripple. This undesired current ripple is difficult to filter and can lead to shorter battery life. A control system based on well-known controllers is analyzed and designed. Theoretical analysis is validated experimentally using a single-phase 1-kW prototype.

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Pichon, Hugot, Yves Lembeye, and Jean-Christophe Crebier. "Accurate Efficiency and Power Densities Optimization of Output Inductor of Buck Derived Converters." Applied Sciences 12, no. 18 (September 17, 2022): 9330. http://dx.doi.org/10.3390/app12189330.

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In this article, inductor loss models are developed based on the experimental characterization of off-the-shelf components. The modelling steps and techniques are described and validated. It is shown that the model exhibits fairly good accuracy over a large range of ripple current frequency and magnitude. Then, these models are used, as an illustration, in order to present the possible optimization process of the tradeoff between switching frequency-current ripple magnitude and output inductors value in the case of a Buck-derived converter. This optimization has shown that a large current ripple may lead to minimized losses in some cases. The developed modelling technique aims to represent Joules and iron losses, as well as DC and AC losses of inductors. It is not based on physical behaviour description but on mathematical equations based on a set of experimental characterizations. The modelling technique is not suitable for designing the component itself but is useful for selecting the best component value in the manufacturer’s series of components. Since it remains difficult with the manufacturer datasheet to estimate AC losses accurately with respect to frequency and ripple current magnitude, a specific characterization is carried out to complement the available data.

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Braun, Wilhelm, and Raoul-Martin Memmesheimer. "High-frequency oscillations and sequence generation in two-population models of hippocampal region CA1." PLOS Computational Biology 18, no. 2 (February 17, 2022): e1009891. http://dx.doi.org/10.1371/journal.pcbi.1009891.

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Hippocampal sharp wave/ripple oscillations are a prominent pattern of collective activity, which consists of a strong overall increase of activity with superimposed (140 − 200 Hz) ripple oscillations. Despite its prominence and its experimentally demonstrated importance for memory consolidation, the mechanisms underlying its generation are to date not understood. Several models assume that recurrent networks of inhibitory cells alone can explain the generation and main characteristics of the ripple oscillations. Recent experiments, however, indicate that in addition to inhibitory basket cells, the pattern requires in vivo the activity of the local population of excitatory pyramidal cells. Here, we study a model for networks in the hippocampal region CA1 incorporating such a local excitatory population of pyramidal neurons. We start by investigating its ability to generate ripple oscillations using extensive simulations. Using biologically plausible parameters, we find that short pulses of external excitation triggering excitatory cell spiking are required for sharp/wave ripple generation with oscillation patterns similar to in vivo observations. Our model has plausible values for single neuron, synapse and connectivity parameters, random connectivity and no strong feedforward drive to the inhibitory population. Specifically, whereas temporally broad excitation can lead to high-frequency oscillations in the ripple range, sparse pyramidal cell activity is only obtained with pulse-like external CA3 excitation. Further simulations indicate that such short pulses could originate from dendritic spikes in the apical or basal dendrites of CA1 pyramidal cells, which are triggered by coincident spike arrivals from hippocampal region CA3. Finally we show that replay of sequences by pyramidal neurons and ripple oscillations can arise intrinsically in CA1 due to structured connectivity that gives rise to alternating excitatory pulse and inhibitory gap coding; the latter denotes phases of silence in specific basket cell groups, which induce selective disinhibition of groups of pyramidal neurons. This general mechanism for sequence generation leads to sparse pyramidal cell and dense basket cell spiking, does not rely on synfire chain-like feedforward excitation and may be relevant for other brain regions as well.

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Cansizoglu, Mehmet F., Mesut Yurukcu, and Tansel Karabacak. "Ripple Formation during Oblique Angle Etching." Coatings 9, no. 4 (April 22, 2019): 272. http://dx.doi.org/10.3390/coatings9040272.

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Chemical removal of materials from the surface is a fundamental step in micro- and nano-fabrication processes. In conventional plasma etching, etchant molecules are non-directional and perform a uniform etching over the surface. However, using a highly directional obliquely incident beam of etching agent, it can be possible to engineer surfaces in the micro- or nano- scales. Surfaces can be patterned with periodic morphologies like ripples and mounds by controlling parameters including the incidence angle with the surface and sticking coefficient of etching particles. In this study, the dynamic evolution of a rippled morphology has been investigated during oblique angle etching (OAE) using Monte Carlo simulations. Fourier space and roughness analysis were performed on the resulting simulated surfaces. The ripple formation was observed to originate from re-emission and shadowing effects during OAE. Our results show that the ripple wavelength and root-mean-square roughness evolved at a more stable rate with accompanying quasi-periodic ripple formation at higher etching angles (θ > 60°) and at sticking coefficient values (Sc) 0.5 ≤ Sc ≤ 1. On the other hand, smaller etching angle (θ < 60°) and lower sticking coefficient values lead to a rapid formation of wider and deeper ripples. This result of this study can be helpful to develop new surface patterning techniques by etching.

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Hasanien, Hany M., S. M. Muyeen, and Junji Tamura. "Torque ripple minimization of axial laminations switched reluctance motor provided with digital lead controller." Energy Conversion and Management 51, no. 12 (December 2010): 2402–6. http://dx.doi.org/10.1016/j.enconman.2010.05.004.

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Yu, Zhen, and Yuan Zhang. "Diagnosis of the Misaligned Faults of the Vertical Test Instrument of High-Precision Industrial Robot Reducer." Shock and Vibration 2021 (July 26, 2021): 1–17. http://dx.doi.org/10.1155/2021/5516025.

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High-precision reducer is the core component of industrial robots. In order to achieve the comprehensive performance testing of precision reducers, an instrument with a vertical layout and a cylindrical structure is designed. As a rotating machine, the inevitable coupling misalignment of the instrument can lead to vibration faults which lead to errors in the test. So it is pretty necessary to diagnose and monitor the coupling misalignment while the instrument is working. The causes of the coupling misaligned fault of the instrument and the relationship between the misalignment fault and torque ripple are analyzed in this paper. A method of using the torque transducer in the measurement chain of the instrument to diagnose the coupling misalignment is proposed in this paper. Many experiments have been done to test the capability of detecting the coupling misalignment using this method. Experimental results show that the amplitude of torque ripple of the shaft is linearly related to the coupling misalignment and is quadratically related to the rotation speed of the shaft when the misalignment exists in the shaft. The combination of components at the rotation frequency (fr) and the additional components can be used to diagnose faults due to coupling misalignment.

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Tzouganakis, Panteleimon, Vasilios Gakos, Christos Kalligeros, Christos Papalexis, Antonios Tsolakis, and Vasilios Spitas. "Torque ripple investigation in coaxial magnetic gears." MATEC Web of Conferences 366 (2022): 01004. http://dx.doi.org/10.1051/matecconf/202236601004.

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Magnetic gears offer significant advantages such as low noise and vibration level, lower maintenance and higher reliability compared to mechanical gears and are suitable for many applications in the industry. The coaxial magnetic gear has been extensively discussed in the literature, since it achieves higher torque densities amongst other magnetic gear configurations. The magnetic field is generated by permanent magnets mounted on the two rotors and a modulator between them. The modulator consists of ferromagnetic segments that are typically encased in a resin in order to increase its stiffness without compromising the generated magnetic field. However, due to the development of radial forces, oscillations of the ferromagnetic segments occur, which lead to torque ripples that affect the operation of the coaxial magnetic gear drive in applications where accuracy is required. This work introduces a computationally lightweight analytical 2D model in order to determine the applied radial force on the ferromagnetic segments at each angle of rotation of the two rotors and henceforth calculate the displacement of these segments using FEA. In this way it is possible to assess the variation of the torque (ripple) versus the angle of rotation of the input or output shaft. A parametric investigation examining the influence of the ferromagnetic segment thickness on the resulting torque ripple of a specific drive was carried out illustrating the benefits of the analytical models developed herein.

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Erfort, Gareth, Theodor W. von Backström, and Gerhard Venter. "Reduction in the torque ripple of a vertical axis wind turbine through foil pitching optimization." Wind Engineering 44, no. 2 (March 21, 2019): 115–24. http://dx.doi.org/10.1177/0309524x19836711.

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Vertical axis wind turbines have a place in the small scale renewable energy market. They are not currently implemented on a commercial scale but have found a niche space in urban areas. Here, the turbulent wind conditions and limited space are more easily tapped into with a vertical axis wind turbine. However, the challenges facing these types of turbines have hampered deployment. One of these issues is the fluctuating torque experienced during operation, which can lead to over-designed power trains. Genetic- and gradient-based optimization is applied to an analytical model of a vertical axis wind turbine, in order to reduce the torque fluctuation while attempting to maintain a high power coefficient. The reduction in torque ripple is achieved through a sinusoidal pitching motion of the blades. The torque ripple can be reduced by 10% with a similar reduction in power coefficient.

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Zhang, Kaibi, Peng Wu, and Fei Xiong. "Design Method of DC Bus Capacitor for Two-Stage AC/DC Converter." Journal of Physics: Conference Series 2360, no. 1 (November 1, 2022): 012017. http://dx.doi.org/10.1088/1742-6596/2360/1/012017.

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In the single-phase two-stage AC/DC converter system, the inherent power fluctuation of double frequency will lead to the double frequency fluctuation of DC bus voltage, which will affect the stable operation of the converter. In addition, this fluctuation will also raise the current stress of the double active bridge. This makes it more difficult to design DC bus capacitance parameters. In this paper, a design method of DC bus capacitors based on high ripple operation is proposed, and the theoretical limit of DC bus voltage ripple is analyzed. On the premise of considering stable operation and current stress of converter, the capacitance of DC bus is reduced to improve the power density of the system. The design of capacitance parameters has a theoretical basis to follow. Finally, the correctness and effectiveness of the method are verified by examples.

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Liu, Jian, Lihui Wang, and Zhengqi Tian. "Adaptive identification methods of nonlinear random electrical signal." International Journal of Applied Electromagnetics and Mechanics 64, no. 1-4 (December 10, 2020): 431–38. http://dx.doi.org/10.3233/jae-209349.

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The nonlinearity of the electric vehicle DC charging equipment and the complexity of the charging environment lead to the complex and changeable DC charging signal of the electric vehicle. It is urgent to study the distortion signal recognition method suitable for the electric vehicle DC charging. Focusing on the characteristics of fundamental and ripple in DC charging signal, the Kalman filter algorithm is used to establish the matrix model, and the state variable method is introduced into the filter algorithm to track the parameter state, and the amplitude and phase of the fundamental waves and each secondary ripple are identified; In view of the time-varying characteristics of the unsteady and abrupt signal in the DC charging signal, the stratification and threshold parameters of the wavelet transform are corrected, and a multi-resolution method is established to identify and separate the unsteady and abrupt signals. Identification method of DC charging distortion signal of electric vehicle based on Kalman/modified wavelet transform is used to decompose and identify the signal characteristics of the whole charging process. Experiment results demonstrate that the algorithm can accurately identify ripple, sudden change and unsteady wave during charging. It has higher signal to noise ratio and lower mean root mean square error.

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Mekrini, Zineb, and Seddik Bri. "Fuzzy Logic Application for Intelligent Control of An Asynchronous Machine." Indonesian Journal of Electrical Engineering and Computer Science 7, no. 1 (July 1, 2017): 61. http://dx.doi.org/10.11591/ijeecs.v7.i1.pp61-70.

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<p>The aim of this article is propose a method to improve the direct torque control and design a Fuzzy Logic based Controller which can take necessary control action to provide the desired torque and flux of an asynchronous machine. It’s widely used in the industrial application areas due to several features such as fast torque response and less dependence on the rotor parameters. The major problem that is usually associated with DTC control is the high torque ripple as it is not directly controlled. The high torque ripple causes vibrations to the motor which may lead to component lose, bearing failure or resonance. The fuzzy logic controller is applied to reduce electromagnetic torque ripple. In this proposed technique, the two hysteresis controllers are replaced by fuzzy logic controllers and a methodology for implementation of a rule based fuzzy logic controller are presented. The simulation by Matlab/Simulink was built which includes induction motor d-q model, inverter model, fuzzy logic switching table and the stator flux and torque estimator. The validity of the proposed method is confirmed by the simulative results of the whole drive system and results are compared with conventional DTC method. </p>

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Wu, Yihong, Fengxian Bai, and Jianzhong Sun. "Vector Proportional Integral Control with Delay Compensation for Stator Excited Doubly Salient Synchronous Motors." Journal of Physics: Conference Series 2378, no. 1 (December 1, 2022): 012039. http://dx.doi.org/10.1088/1742-6596/2378/1/012039.

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Abstract This paper proposes a novel current control technique to solve the problem that the special doubly salient structure of the studied stator excitation doubly salient synchronous motor (SEDSSM) causes the motor back EMF to cause large harmonic current and torque ripple. Based on the space vector pulse width modulation sinusoidal drive method, a vector proportional-integral controller with delay compensation (VPIC) is introduced into the current loop to replace the traditional PI controller to control the motor. The SEDSSM stator current under the current loop control mode of conventional PI controller is analyzed, and it is found that its waveform is obviously affected and disturbed by the third harmonic current, which will cause torque pulsation. Therefore, additional resonance items are considered to be introduced into the controller to suppress its harmonic. At the same time, considering that the digital delay in the application of the digital system will lead to an unstable state of the control system under the vector proportional-integral controller, the vector proportional-integral controller with delay compensation is introduced for this purpose. Experimental data tested on a 12/8 SEDSSM prototype show that the VPIC controller can significantly reduce stator current ripple and motor torque ripple compared to the existing PI controller.

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Gupta, Varun, D. S. Chauhan, and Kamlesh Dutta. "Regression Testing-Based Requirement Prioritization of Mobile Applications." International Journal of Systems and Service-Oriented Engineering 3, no. 4 (October 2012): 20–39. http://dx.doi.org/10.4018/jssoe.2012100102.

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Mobile software application development process must be matured enough to handle the challenges (especially market related) associated with the development of high quality mobile software development. Ever increasing number of both mobile users and mobile applications had presented software engineers with the challenge of satisfying billions of users with high quality software applications to be delivered within deadline and budgets. Always there had been a lot of pressure to develop complex software categorized by thousands of requirements, under resource constrained environment. Requirement prioritization is one of the activities undertaken by software engineer to deliver partial software product to its customers such that most important requirements are implemented in the earliest releases. During next releases some changed and pending requirements are implemented, an activity that generates ripple effects. Such ripple effects need to be tested by executing modified source code against test cases of previous releases (regression testing). Regression testing is a very effortful activity that requires a software tester to select test cases that have high fault detection capability, execute the modified code against selected test cases and performing debugging. This regression testing activity can be lowered to the maximum extend by considering dependencies between requirements during the time of requirement prioritization. Thus requirement prioritization will be carried out not only against aspects like cost, time, risks, business values etc but against dependencies also. The aim is to implement almost all dependent highest priority requirements in current release so that implementation of new requirements is unlikely to have ripple effects. Changes in requirements might not be related to variable usage and definition and might not involve a change in functionality. In such cases there is no need to select already executed test cases of previous versions. Module dependencies can lead to test case selections of previous versions if changes of requirement lead to ripple effects. This paper aims to implement highest priority requirements such that regression testing is performed to minimum thereby improving development process of mobile applications. The proposed technique had been successfully evaluated on Android based notification software application that meets the specification of Aakash tablets.

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Zhang, Shuai, Ming Sun, and Baojiang Sun. "Research on Speed Regulation performance of switched reluctance Motor based on nonlinear active disturbance rejection." Journal of Physics: Conference Series 2263, no. 1 (April 1, 2022): 012017. http://dx.doi.org/10.1088/1742-6596/2263/1/012017.

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Abstract The state has vigorously advocated new energy electric vehicles in recent years. Compared with other motors, switched reluctance motor has the advantages of superior speed regulation performance, low production cost and strong controllability. However, due to its double salient structure, it is easy to produce magnetic circuit saturation, and its control is non-linear, which is easy to lead to large torque ripple and strong noise. To solve this problem, a control strategy combining active disturbance rejection control and direct torque is proposed to suppress torque ripple. A simulation model is built and calculated with simulation software. At the same time, it is compared with PI control and fuzzy PID control under direct torque control. Finally, the simulation experiment is carried out on a 6 / 4 motor. The simulation results also show that the direct torque control strategy based on active disturbance rejection control technology can effectively control the torque and speed of switched reluctance motor.

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KIm, Choon-Tack, and Young-Seok Kim. "The Study of Ripple Reduction of the PFC CCM Flyback Converter without Electrolytic Capacitor for LED Lightings using LC Resonant Filter." Transactions of The Korean Institute of Electrical Engineers 65, no. 4 (April 1, 2016): 601–10. http://dx.doi.org/10.5370/kiee.2016.65.4.601.

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Yano, Masafumi, and Shinichi Okuda. "Does a Ripple of Ca2+ Leak Develop Into a Rogue Wave That Can Trigger Pathological Hypertrophy?" Journal of the American College of Cardiology 63, no. 15 (April 2014): 1580–82. http://dx.doi.org/10.1016/j.jacc.2013.10.064.

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Mao, Jianping. "Cosmic Background." European Journal of Applied Physics 3, no. 1 (February 20, 2021): 67–70. http://dx.doi.org/10.24018/ejphysics.2021.3.1.51.

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A possibility is that in cosmic background, primordial photon lattice where emerges a way to mass conservation, a photon was disturbed to create a spin then lead to its neighbors consecutively avalanching -- CMB -- into this a small ripple, which inverse spin directions pointing to a world was made of matter or antimatter whichever is parity violation; now cosmos was like an expanding hole -- an isotropic gravity field -- in photon lattice that influenced on everything, so inertia will be partly clarified.

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Ismail, Huzainirah, Fazlli Patkar, Auzani Jidin, Aiman Zakwan Jidin, Noor Azida Noor Azlan, and Tole Sutikno. "Constant Switching Frequency and Torque Ripple Minimization of DTC of Induction Motor Drives with Three-level NPC Inverter." International Journal of Power Electronics and Drive Systems (IJPEDS) 8, no. 3 (September 1, 2017): 1035. http://dx.doi.org/10.11591/ijpeds.v8.i3.pp1035-1049.

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<p>Direct Torque Control (DTC) is widely applied for ac motor drives as it offers high performance torque control with a simple control strategy. However, conventional DTC poses some disadvantages especially in term of variable switching frequency and large torque ripple due to the utilization of torque hysteresis controller. Other than that, performance of conventional DTC fed by two-level inverter is also restricted by the limited numbers of voltage vectors which lead to inappropriate selection of voltage vectors for different speed operations. This research aims to propose a Constant Switching Frequency (CSF) torque controller for DTC of induction motor (IM) fed by three-level Neutral-Point Clamped (NPC) inverter. The proposed torque controller utilizes PI controller which apply different gain for different speed operation. Besides, the utilization of NPC inverter provides greater number of voltage vectors which allow appropriate selection of voltage vectors for different operating condition. Using the proposed method, the improvement of DTC drives in term of producing a constant switching operation and minimizing torque ripple are achieved and validated via experimental results.</p>

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Restiani, Dian. "KOMBINASI ALGORITMA CART DAN RIPPER UNTUK MENDIAGNOSIS PENYAKIT LIVER BERBASIS CORRELATION BASED FEATURE SELECTION." JURNAL TEKNIK INFORMATIKA 11, no. 1 (May 4, 2018): 31–36. http://dx.doi.org/10.15408/jti.v11i1.6660.

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ABSTRAK Hati merupakan organ yang paling besar dan penting bagi tubuh kita. Kita tidak bisa hidup tanpa hati. Penyakit hati tidak mudah ditemukan pada stadium awal. Penanganan pasien penyakit hati pada stadium awal akan memperpanjang usia pasien. Untuk mendeteksi penyakit hati, pasien harus melakukan tes darah. Kesalahan dalam mendiagnosis penyakit dan penentuan konsumsi obat dapat menyebabkan hal yang membahayakan bagi kesehatan pasien bahkan dapat menyebabkan kematian. Ini menjadikan para peneliti dan praktisi memusatkan perhatiannya untuk mendeteksi/mendiagnosis penyakit liver dan mencegahnya karena penyakit ini bisa menimbulkan kematian jika sudah akut. Metode yang digunakan dalam penelitian ini yaitu CRISP-DM. Algoritma yang digunakan dalam penelitian ini adalah kombinasi CART dan RIPPER dengan menggunakan dataset diambil dari repository database UCI Indian Liver Patient Dataset yang terdiri dari data klinis pasien yang terdeteksi positif dan negatif penyakit liver. Hasil penelitian ini dengan menggunakan kombinasi rule hasil algoritma CART dan algoritma RIPPER dari confusion matrix didapatkan hasil akurasi sebesar 81%, sensitifitas/recall 0,63%, spesifisitas 0,91%, precision 0,80% dan f-measure sebesar 0,70% pada dataset ILPD tanpa melakukan seleksi fitur, sedangkan pada hasil akurasi dataset ILPD dengan melakukan seleksi fitur yaitu akurasi 70% dengan sensitifitas/recall 0,84%, spesifisitas 0,59%, precision 0,58% dan f-measure 0,70%. Dari hasil tersebut dapat disimpulkan bahwa untuk mendiagnosis penyakit liver dengan menggunakan kombinasi algoritma CART dan RIPPER tanpa melakukan seleksi fitur. ABSTRACT The liver is the largest organ and important for our body. We can not live without the heart. Liver disease is not easy to find in the early stages. For detection of liver disease patients in the early stages will prolong the patient's age. To detect liver disease, the patient must perform a blood test. Mistakes in diagnosing illness and determining drug consumption can cause harm to the health of the patient and even cause death. This allows researchers and practitioners to focus on detecting/diagnosing liver disease and preventing it because it can lead to death if it is acute. The method used in this research is CRISP-DM. The algorithm used in this study is a combination of CART and RIPPER using dataset taken from the UCI Indian Liver patient data repository Dataset consisting of clinical data of patients who detected positive and negative liver disease. The result of this research by using combination of rule result from CART algorithm and RIPPER algorithm of confusion matrix obtained accuracy 81%, sensitivity/recall 0.63%, specificity 0,91%, precision 0,80% and f-measure 0,70% on the ILPD dataset without performing feature selection, whereas on the accuracy results of the ILPD dataset by performing feature selection is accuracy 70%, with recall/sensitivity 0.84%, specificity 0.59%, precision 0.58% and f-measure 0.70 %. From these results it can be concluded that to diagnose liver disease by using a combination of CART and RIPPER algorithms without performing feature selection. How To Cite : Restiani, D. (2018). KOMBINASI ALGORITMA C-RIPPER UNTUK MENDIAGNOSIS PENYAKIT LIVER. Jurnal Teknik Informatika, 11(1), 31-36. doi 10.15408/jti.v11i1.6660 Permalink/DOI: http://dx.doi.org/10.15408/jti.v11i1.6660

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Baburajan, Silpa, Haoran Wang, Dinesh Kumar, Qian Wang, and Frede Blaabjerg. "DC-Link Current Harmonic Mitigation via Phase-Shifting of Carrier Waves in Paralleled Inverter Systems." Energies 14, no. 14 (July 13, 2021): 4229. http://dx.doi.org/10.3390/en14144229.

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DC-connected parallel inverter systems are gaining popularity in industrial applications. However, such parallel systems generate excess current ripple (harmonics) at the DC-link due to harmonic interactions between the inverters in addition to the harmonics from the PWM switching. These DC-link harmonics cause the failure of fragile components such as DC-link capacitors. This paper proposes an interleaving scheme to minimize the current harmonics induced in the DC-link of such a system. First, the optimal phase-shift angle for the carrier signal is investigated using the analytical equations, which provides maximum capacitor current ripple cancellation (i.e., at the main switching frequency harmonic component). These optimally phase-shifted switching cycles lead to variations of the output current ripples, which, when summed together at the DC-link, result in the cancellations of the DC-link current ripples. The results show that when the carrier waves of the two inverters are phase-shifted by a 90° angle, the maximum high-frequency harmonic ripple cancellation occurs, which reduces the overall root-mean-square (RMS) value of the DC-capacitor current by almost 50%. The outcome of this proposed solution is a cost-effective DC-harmonics mitigating strategy for the industrial designers to practically configure multi-inverter systems, even when most of the drives are not operating at rated power levels. The experimental and simulation results presented in this paper verify the effectiveness of the proposed carrier-based phase-shifting scheme for two different configurations of common DC connected multi-converter systems.

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Jeon, Yong-Sung, Dal-Lae Jin, Jae-Du La, and Young-Seok Kim. "Study of the Elimination of the Electrolytic Capacitors and Reduction of the Ripple Current on the Output Node in the One-Stage PFC Flyback Converter for the LED Lighting." Transactions of The Korean Institute of Electrical Engineers 61, no. 11 (November 1, 2012): 1625–33. http://dx.doi.org/10.5370/kiee.2012.61.11.1625.

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Hyun, Steve, Jimin Lee, Jong-Min Kim, and Chulhee Jun. "What Coins Lead in the Cryptocurrency Market: Using Copula and Neural Networks Models." Journal of Risk and Financial Management 12, no. 3 (August 8, 2019): 132. http://dx.doi.org/10.3390/jrfm12030132.

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Exploring dependence structures between financial time series has been important within a wide range of applications. The main aim of this paper is to examine dependence relationships among five well-known cryptocurrencies—Bitcoin, Ethereum, Litecoin, Ripple, and Stella—by a copula directional dependence (CDD). By employing a neural network autoregression model to avoid the serial dependence in each individual cryptocurrency, we generate residuals of the fitted models with time series of daily log-returns in percentage of the five cryptocurrencies and then we apply a Gaussian copula marginal beta regression model to the residuals to explore the CDD. The results show that the CDD from Bitcoin to Litecoin is highest among all ordered directional dependencies and the CDDs from Ethereum to the other four cryptocurrencies are relatively higher than the CDDs to Ethereum from those cryptocurrencies. This finding implies that the return shocks of Bitcoin have the most effect on Litecoin and the return shocks of Ethereum relatively influence the shocks on the other four cryptocurrencies instead of being affected by them. This allows investors to build the market-timing strategies by observing the directional flow of return shocks among cryptocurrencies.

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Li, Weijiang, Jiahong Wen, Bo Xu, Xiande Li, and Shiqiang Du. "Integrated Assessment of Economic Losses in Manufacturing Industry in Shanghai Metropolitan Area Under an Extreme Storm Flood Scenario." Sustainability 11, no. 1 (December 27, 2018): 126. http://dx.doi.org/10.3390/su11010126.

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In this paper, we developed an integrated methodology for assessing asset damage, production capacity loss, and inter-sector ripple loss using the depth-damage curve, Cobb-Douglas production function and Input-Output model. We applied this methodology to the detailed individual manufacturing firms in Shanghai under an extreme storm floods scenario to simulate the disaster impact propagation from local individual firms to the entire industrial system and comprehensively estimate the resulting economic losses and their spatial distribution. Our results show that given no floodwall protection, a 1000-year storm flood scenario would cause direct asset damage of US $21 billion to the Shanghai manufacturing industry, including fixed asset damage of US $12 billion and inventory damage of US $9 billion. Due to the shortage of input productive factors of asset and labor, it would further lead to production capacity loss of US $24 billion. In addition, affected manufacturing industry would indirectly result in ripple loss of US $60 billion among dependent sectors, which has a significant amplifier effect. Our results have important implications for reasonable cost-benefit analysis of structural flood control measures in coastal areas, as well as for manufacturing firm location planning and resilience strategy decision-making.

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Sahar, Aaminah Najmus. "THE RIPPLE EFFECT OF COVID-19 PANDEMIC IN HEALTHCARE." International Journal of Research -GRANTHAALAYAH 8, no. 12 (December 24, 2020): 30–35. http://dx.doi.org/10.29121/granthaalayah.v8.i12.2020.2518.

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The COVID-19 Pandemic has disrupted life and changed what we knew as normal, for the past 9 months. Although the first case of COVID-19 was identified in Wuhan, China in mid-December 2019, it was coined as a Pandemic by WHO in March 2020. The COVID-19 Pandemic has impacted each and everyone and caused a ripple effect in all areas of life, the healthcare is no exception. With its novel nature, limited information, lack of resources, risky working conditions, and high spikes in cases, it has caused a massive overload on the healthcare systems. It has caused mental health disturbances not just in the frontline workers and COVID-19 survivors but also in the general public owing to uncertainty, isolation, fear, anxiety, andmisinformation. In addition to this, there has also been an increase in the prescription of antibiotics which stems from the inability to examine the patient physically and obtain samples for cultures as consultations are scheduled through telemedicine. Antimicrobial resistance(AMR) is considered to be further potentiated during the Pandemic as Antimicrobial stewardship programs (ASP) have been disrupted and there is an increase in hospital admissions and intubations of patients. Measures like lockdown and travel restrictions placed to curb the spread of the virus have negatively impacted individuals with addictions and substance use disorders (SUD’s) due to inability to access de-addiction centers, increased isolation, and inability to obtain toxicants which lead to the use of adulterated substances and in some cases withdrawal symptoms. The lockdown has also caused delays in the treatment of chronic and co-morbid diseases like Diabetes, Cardiovascular diseases, Cancer, Dialysis leading to poor disease management and progression of the disease. It has also impacted regular vaccination schedules and periodic health checkups leading to late diagnosis of diseases.

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Van Heerden, Michelle. "Exploring Habitus and Writer Identities: An ethnographic study of writer identity construction in the FET Phase at two schools in the Western Cape." Multilingual Margins: A journal of multilingualism from the periphery 2, no. 2 (November 8, 2018): 67. http://dx.doi.org/10.14426/mm.v2i2.73.

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Globalisation processes have resulted in increasingly pluralistic societies, a phenomenon with ripple effects in contexts such as universities, which now provide access to heterogeneous student populations with diverse rituals, beliefs, cultures and languages. For this reason, deficit discourses that frame students as underprepared for the demands of tertiary studies are a global phenomenon (Boughey, 2003; Lillis, 2003; Lea & Street, 1998). Furthermore, the different identities, histories and dispositions (Bourdieu, 1990) of students result in hybrid linguistic repertoires, with some repertoires being more powerful than others (Blommaert, 2001; Blommaert, Collins &Slembrouck, 2005; Rampton, 2003). Therefore, having access to the preferred linguistic repertoire - in most cases standard English - is an asset, because this repertoire is more closely aligned than others to tertiary education practices and discourses. As a result, the scholarly community can be daunting for many first-year students whose linguistic identities are not always aligned to institutional values, practices and discourses; students can easily be indexed as under-achieving or incompetent.

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Smith, M. J., D. T. Gladwin, and D. A. Stone. "An analysis of the influence of high-frequency ripple currents on dynamic charge acceptance in lead-acid batteries." Journal of Energy Storage 22 (April 2019): 27–35. http://dx.doi.org/10.1016/j.est.2019.01.024.

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Karaömer, Yunus. "The time-varying correlation between cryptocurrency policy uncertainty and cryptocurrency returns." Studies in Economics and Finance 39, no. 2 (February 14, 2022): 297–310. http://dx.doi.org/10.1108/sef-10-2021-0436.

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Purpose This study aims to analyze the time-varying correlation between the cryptocurrency policy uncertainty (UCRY Policy) and cryptocurrency returns. More specifically, it analyzes whether these correlations vary according to the uncertainty attributable to salient events such as China banning ICOs, cryptocurrency exchanges attacks, Coronavirus (Covid-19) pandemic crisis and the United States (U.S.) Security and Exchange Commission’s (SEC’s) announcement about Ripple. Design/methodology/approach To measure the dynamic relationship, it uses the dynamic conditional correlation (DCC) model of Engle (2002) to consider time variation in UCRY Policy and cryptocurrency returns. The data set encompasses the weekly frequency data of the UCRY Policy and Bitcoin (BTC), Ethereum (ETH), Litecoin (LTC), Ripple (XRP), Stellar (XLM), Dash (DASH), Monero (XMR) from 4 September 2016, to 21 February 2021. Findings Empirical findings indicate that the correlations between the UCRY Policy and the BTC, ETH, LTC, XRP, XLM, DASH and XMR returns are consistently negative. Thus, an increase in the volatility of the UCRY Policy can lead to a decrease in volatility for BTC, ETH, LTC, XRP, XLM, DASH and XMR returns. Besides, these findings indicate that the estimated DCC is not only time-varying but also substantially responsive to salient events, such as China banning ICOs, cryptocurrency exchanges attacks, the Covid-19 pandemic crisis and SEC’s announcement about Ripple. Besides, empirical findings show that cryptocurrency returns are adversely impacted by UCRY Policy during the salient events (China bans ICOs, the hack of cryptocurrency exchanges, Covid-19 crisis), suggesting their failure to act as a hedge or safe-haven asset. Originality/value To the best of the author’s knowledge, this study investigates the time-varying correlation between UCRY Policy and cryptocurrency returns. Besides, this study may be useful for new studies and fill a gap in the finance literature, due to the limited number of studies on the UCRY Policy in the finance literature.

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Birkie, Seyoum Eshetu, and Paolo Trucco. "Do not expect others do what you should! Supply chain complexity and mitigation of the ripple effect of disruptions." International Journal of Logistics Management 31, no. 1 (February 10, 2020): 123–44. http://dx.doi.org/10.1108/ijlm-10-2018-0273.

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PurposeRecent studies have argued that companies may actively implement practices to mitigate disruptions in their supply chain and reduce the extent of damage on performance. Other studies have shown that disruptions may propagate in supply chains, leading to consequences that are more negative and raising doubts on the effectiveness of mitigation strategies implemented downstream. This study investigates the influence of supply chain complexity on the two phenomena and their interplay, taking a focal company's perspective.Design/methodology/approachA systematic procedure for data collection, encoding and aggregation based on incident data mainly from secondary sources was used. Multiple regression models were run to analyse direct and moderation effects involving resilience, distance of impact location from trigger point, and supply chain complexity on weighted performance change.FindingsSupply chain complexity is found to have positive moderation on the ripple effect of disruption. Resilience capability remains to have dominating direct positive effect in mitigating disruptions when supply chain complexity is taken into account.Research limitations/implicationsThis study extends the research discourse on supply chain resilience and disruption management with focus on the supply side. It demonstrates that, along with the severity of the disruption scenario, the ripple effect must also be considered when analyzing the benefits of resilience practices implemented by the focal company.Practical implicationsComplexity in the supply chain can only help to smooth-out the rippling effects of a disruption, which go largely beyond supply-demand unbalances and lead time fluctuations. To mitigate it better, the focal company has to act proactively with adequate resilience practices, which also connects to the importance of better visibility across multiple supply chain tiers.Originality/valueTo the best of the authors' knowledge, this is the first study that empirically tests the benefits of resilience practices and the ripple effect of disruptions under the moderation role of supply chain complexity.

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Amamra, Sid-Ali, Yashraj Tripathy, Anup Barai, Andrew D. Moore, and James Marco. "Electric Vehicle Battery Performance Investigation Based on Real World Current Harmonics." Energies 13, no. 2 (January 19, 2020): 489. http://dx.doi.org/10.3390/en13020489.

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Electric vehicle (EV) powertrains consist of power electronic components as well as electric machines to manage the energy flow between different powertrain subsystems and to deliver the necessary torque and power requirements at the wheels. These power subsystems can generate undesired electrical harmonics on the direct current (DC) bus of the powertrain. This may lead to the on-board battery being subjected to DC current superposed with undesirable high- and low- frequency current oscillations, known as ripples. From real-world measurements, significant current harmonics perturbations within the range of 50 Hz to 4 kHz have been observed on the high voltage DC bus of the EV. In the limited literature, investigations into the impact of these harmonics on the degradation of battery systems have been conducted. In these studies, the battery systems were supplied by superposed current signals i.e., DC superposed by a single frequency alternating current (AC). None of these studies considered applying the entire spectrum of the ripple current measured in the real-world scenario, which is focused on in this research. The preliminary results indicate that there is no difference concerning capacity fade or impedance rise between the cells subjected to just DC current and those subjected additionally to a superposed AC ripple current.

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Bianchini, Claudio, Ambra Torreggiani, Matteo Davoli, and Alberto Bellini. "Design of Low-Cost Synchronous Machine to Prevent Demagnetization." Energies 13, no. 14 (July 10, 2020): 3566. http://dx.doi.org/10.3390/en13143566.

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The request for high efficiency motor paves the way for the replacement of induction motors with permanent magnet synchronous motors. Although the efficiency is increased, for medium and high power, the current ripple causes significant additional losses in the magnet and lamination; and, high temperature can lead to demagnetization. In this paper, a new rotor topology is proposed and compared to a traditional surface permanent magnet rotor to reduce the magnet losses and protect them from demagnetization. A reference surface permanent magnet machine is compared with the proposed one in terms of performance and magnet losses. Both analytical and experimental analysis are carried out and discussed.

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Journal articles on the topic 'Rippon Lea'

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