Artykuły w czasopismach: „Three Phase sampling”

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Sang, Hailin, Kenneth K. Lopiano, Denise A. Abreu, Andrea C. Lamas, Pam Arroway i Linda J. Young. "Adjusting for Misclassification: A Three-Phase Sampling Approach". Journal of Official Statistics 33, nr 1 (1.03.2017): 207–22. http://dx.doi.org/10.1515/jos-2017-0011.

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Abstract The United States Department of Agriculture’s National Agricultural Statistics Service (NASS) conducts the June Agricultural Survey (JAS) annually. Substantial misclassification occurs during the prescreening process and from field-estimating farm status for nonresponse and inaccessible records, resulting in a biased estimate of the number of US farms from the JAS. Here, the Annual Land Utilization Survey (ALUS) is proposed as a follow-on survey to the JAS to adjust the estimates of the number of US farms and other important variables. A three-phase survey design-based estimator is developed for the JAS-ALUS with nonresponse adjustment for the second phase (ALUS). A design-unbiased estimator of the variance is provided in explicit form.

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Magnussen, Steen. "Stepwise estimators for three-phase sampling of categorical variables". Journal of Applied Statistics 30, nr 5 (czerwiec 2003): 461–75. http://dx.doi.org/10.1080/0266476032000053628.

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Saliby, Eduardo, i Ray J. Paul. "Implementing Descriptive Sampling in Three-Phase Discrete Event Simulation Models". Journal of the Operational Research Society 44, nr 2 (luty 1993): 147. http://dx.doi.org/10.2307/2584363.

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Carugati, Ignacio, Sebastian Maestri, Patricio G. Donato, Daniel Carrica i Mario Benedetti. "Variable Sampling Period Filter PLL for Distorted Three-Phase Systems". IEEE Transactions on Power Electronics 27, nr 1 (styczeń 2012): 321–30. http://dx.doi.org/10.1109/tpel.2011.2149542.

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Saliby, Eduardo, i Ray J. Paul. "Implementing Descriptive Sampling in Three-Phase Discrete Event Simulation Models". Journal of the Operational Research Society 44, nr 2 (luty 1993): 147–60. http://dx.doi.org/10.1057/jors.1993.27.

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Lepage, Kyle Q., Mark A. Kramer i Uri T. Eden. "Some Sampling Properties of Common Phase Estimators". Neural Computation 25, nr 4 (kwiecień 2013): 901–21. http://dx.doi.org/10.1162/neco_a_00422.

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The instantaneous phase of neural rhythms is important to many neuroscience-related studies. In this letter, we show that the statistical sampling properties of three instantaneous phase estimators commonly employed to analyze neuroscience data share common features, allowing an analytical investigation into their behavior. These three phase estimators—the Hilbert, complex Morlet, and discrete Fourier transform—are each shown to maximize the likelihood of the data, assuming the observation of different neural signals. This connection, explored with the use of a geometric argument, is used to describe the bias and variance properties of each of the phase estimators, their temporal dependence, and the effect of model misspecification. This analysis suggests how prior knowledge about a rhythmic signal can be used to improve the accuracy of phase estimates.

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Fattorini, Lorenzo, Marzia Marcheselli i Caterina Pisani. "A three-phase sampling strategy for large-scale multiresource forest inventories". Journal of Agricultural, Biological, and Environmental Statistics 11, nr 3 (wrzesień 2006): 296–316. http://dx.doi.org/10.1198/108571106x130548.

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Becker, Benjamin, Christian Kochleus, Denise Spira, Christel Möhlenkamp, Julia Bachtin, Stefan Meinecke i Etiënne L. M. Vermeirssen. "Passive sampler phases for pesticides: evaluation of AttractSPE™ SDB-RPS and HLB versus Empore™ SDB-RPS". Environmental Science and Pollution Research 28, nr 9 (12.01.2021): 11697–707. http://dx.doi.org/10.1007/s11356-020-12109-9.

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AbstractIn this study, three different passive sampling receiving phases were evaluated, with a main focus on the comparability of established styrene-divinylbenzene reversed phase sulfonated (SDB-RPS) sampling phase from Empore™ (E-RPS) and novel AttractSPE™ (A-RPS). Furthermore, AttractSPE™ hydrophilic-lipophilic balance (HLB) disks were tested. To support sampling phase selection for ongoing monitoring needs, it is important to have information on the characteristics of alternative phases. Three sets of passive samplers (days 1–7, days 8–14, and days 1–14) were exposed to a continuously exchanged mixture of creek and rainwater in a stream channel system under controlled conditions. The system was spiked with nine pesticides in two peak scenarios, with log KOW values ranging from approx. − 1 to 5. Three analytes were continuously spiked at a low concentration. All three sampling phases turned out to be suitable for the chosen analytes, and, in general, uptake rates were similar for all three materials, particularly for SDB-RPS phases. Exceptions concerned bentazon, where E-RPS sampled less than 20% compared with the other phases, and nicosulfuron, where HLB sampled noticeably more than both SDB-RPS phases. All three phases will work for environmental monitoring. They are very similar, but differences indicate one cannot just use literature calibration data and transfer these from one SDB phase to another, though for most compounds, it may work fine. Graphical abstract

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Mandallaz, Daniel. "A three-phase sampling extension of the generalized regression estimator with partially exhaustive information". Canadian Journal of Forest Research 44, nr 4 (kwiecień 2014): 383–88. http://dx.doi.org/10.1139/cjfr-2013-0449.

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We consider three-phase sampling schemes in which one component of the auxiliary information is known in the very large sample of the so-called null phase and the second component is available only in the large sample of the first phase, whereas the second phase provides the terrestrial inventory data. We extend to three-phase sampling the generalized regression estimator that applies when the null phase is exhaustive, for global and local estimation, and derive its asymptotic design-based variance. The new three-phase regression estimator is particularly useful for reducing substantially the computing time required to treat exhaustively very large data sets generated by modern remote sensing technology such as LiDAR.

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Mekhilef, Saad, Ahmad Maliki Omar i Nasrudin Abd Rahim. "Modeling of Three-Phase Uniform Symmetrical Sampling Digital PWM for Power Converter". IEEE Transactions on Industrial Electronics 54, nr 1 (luty 2007): 427–32. http://dx.doi.org/10.1109/tie.2006.885151.

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Zhu, Ziwei, Jiayong Cao, Qianli Ma i Fazhe Li. "Analysis and Verification of Phase Current Detection Method of Permanent Magnet Synchronous Motor Based on Three Sampling Resistors Configuration". Journal of Physics: Conference Series 2365, nr 1 (1.11.2022): 012012. http://dx.doi.org/10.1088/1742-6596/2365/1/012012.

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Abstract In the permanent magnet synchronous motor (PMSM) control system, the phase current sampling unit is an important part of the whole motor control system. Traditionally, the hall-effect components are used to detecting the phase currents of the PMSM. However, the size of the hardware with Hall-effect components are often large. In this paper, a scheme of detecting the phase currents of PMSM by using three sampling resistors on the main circuit was discussed. In order to overcome the phenomenon that phase currents flow discontinuously across the three sampling resistors, a method for reconstructing the phase currents was proposed. Both simulation results and experimental results show that the phase currents can be reconstructed successfully and the high sampling accuracy can be obtained.

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Ghaeb, Jasim, Mustafa Al-Khawaldeh i Saleh Al-Jazzar. "Influence of Sampling Period on Harmonics of Three- Phase Space Vector Modulated Inverter". British Journal of Applied Science & Technology 17, nr 5 (10.01.2016): 1–8. http://dx.doi.org/10.9734/bjast/2016/28866.

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Juraska, Michal, Ying Huang i Peter B. Gilbert. "Inference on treatment effect modification by biomarker response in a three-phase sampling design". Biostatistics 21, nr 3 (26.12.2018): 545–60. http://dx.doi.org/10.1093/biostatistics/kxy074.

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Summary An objective in randomized clinical trials is the evaluation of “principal surrogates,” which consists of analyzing how the treatment effect on a clinical endpoint varies over principal strata subgroups defined by an intermediate response outcome under both or one of the treatment assignments. The latter effect modification estimand has been termed the marginal causal effect predictiveness (mCEP) curve. This objective was addressed in two randomized placebo-controlled Phase 3 dengue vaccine trials for an antibody response biomarker whose sampling design rendered previously developed inferential methods highly inefficient due to a three-phase sampling design. In this design, the biomarker was measured in a case-cohort sample and a key baseline auxiliary strongly associated with the biomarker (the “baseline surrogate measure”) was only measured in a further sub-sample. We propose a novel approach to estimation of the mCEP curve in such three-phase sampling designs that avoids the restrictive “placebo structural risk” modeling assumption common to past methods and that further improves robustness by the use of non-parametric kernel smoothing for biomarker density estimation. Additionally, we develop bootstrap-based procedures for pointwise and simultaneous confidence intervals and testing of four relevant hypotheses about the mCEP curve. We investigate the finite-sample properties of the proposed methods and compare them to those of an alternative method making the placebo structural risk assumption. Finally, we apply the novel and alternative procedures to the two dengue vaccine trial data sets.

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Tang, Yaojing, Yongle Chang, Jinrui Tang, Bin Xu, Mingkang Ye i Hongbo Yang. "A Novel Faulty Phase Selection Method for Single-Phase-to-Ground Fault in Distribution System Based on Transient Current Similarity Measurement". Energies 14, nr 15 (3.08.2021): 4695. http://dx.doi.org/10.3390/en14154695.

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In modern electrical power distribution systems, the effective operation of inverter-based arc suppression devices relies on the accuracy of faulty phase selection. In the traditional methods of faulty phase selection for single-phase-to-ground faults (SPGs), power frequency-based amplitude and phase characteristics are used to identify the faulty phase. In the field, when a high-resistance SPG occurs in the system, traditional methods are difficult for accurately identifying the faulty phase because of the weak fault components and complicated process. A novel realizable and effective method of faulty phase selection based on transient current similarity measurements is presented when SPGs occur in resonantly grounded distribution systems in this paper. An optimized Hausdorff distance matrix (MOHD) is proposed and constructed by the transient currents of three phases’ similarity measurements within a certain time window of our method. This MOHD is used to select the sampling time window adaptively, which allows the proposed method to be applied to any scale of distribution systems. Firstly, when a SPG occurs, the expressions for the transient phase current mutation in the faulty and sound phases are analyzed. Then, the sampling process is segmented into several selection units (SUs) to form the MOHD-based faulty phase selection method. Additionally, the Hausdorff distance algorithm (HD) is used to calculate the waveform similarities of the transient phase current mutation among the three phases to form the HD-based faulty phase selection method. Finally, a practical resonant grounded distribution system is modeled in PSCAD/EMTDC, and the effectiveness and performance of the proposed method is compared and verified under different fault resistances, fault inception angles, system topologies, sampling time windows and rates of data missing.

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Yuan, Gu, Xing i Chen. "Phase Difference Measurement of Under-Sampled Sinusoidal Signals for InSAR System Phase Error Calibration". Sensors 19, nr 23 (3.12.2019): 5328. http://dx.doi.org/10.3390/s19235328.

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Phase difference measurement of sinusoidal signals can be used for phase error calibration of the spaceborne single-pass interferometric synthetic aperture radar (InSAR) system. However, there are currently very few papers devoted to the discussion of phase difference measurement of high-frequency internal calibration signals of the InSAR system, especially the discussion of sampling frequency selection and the corresponding measuring method when the high-frequency signals are sampled under the under-sampling condition. To solve this problem, a phase difference measurement method for high-frequency sinusoidal signals is proposed, and the corresponding sampling frequency selection criteria under the under-sampling condition is determined. First, according to the selection criteria, the appropriate under-sampling frequency was chosen to sample the two sinusoidal signals with the same frequency. Then, the sampled signals were filtered by limited recursive average filtering (LRAF) and coherently accumulated in the cycle of the baseband signal. Third, the filtered and accumulated signals were used to calculate the phase difference of the two sinusoidal signals using the discrete Fourier transform (DFT), digital correlation (DC), and Hilbert transform (HT)-based methods. Lastly, the measurement accuracy of the three methods were compared respectively by different simulation experiments. Theoretical analysis and experiments verified the effectiveness of the proposed method for the phase error calibration of the InSAR system.

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García-Fernández, Alejandro, Jesús Doval-Gandoy i Diego Pérez-Estévez. "Discrete Fundamental AC Voltage Controller for Three-Phase Standalone Converters". Energies 14, nr 3 (27.01.2021): 650. http://dx.doi.org/10.3390/en14030650.

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Voltage control of standalone converters with LC filter is usually based on proportional-resonant or proportional-integral controllers, which often require further active damping methods to achieve stability. These solutions place design constraints in the selection of the closed-loop pole locations which limit the achievable bandwidth and increase the design complexity. In contrast, in state-space based controllers, the closed-loop poles can be placed freely through state feedback, which makes them particularly suitable for high order plants and/or low sampling frequencies. Among the modern control methods, direct pole placement is a simple technique that enables the establishment of a straightforward relationship between outcome and design, as opposed to more advanced approaches. This paper presents a discrete state-space voltage controller for standalone converters with LC output filter. The proposed method combines the direct pole placement technique with a virtual disturbance observer in order to compensate the effects produced by the load and model mismatches. The design process takes into account both the filter parameters and the sampling frequency, rendering the performance of the obtained controller independent of both. The result is a streamlined design procedure that leads to consistent outcomes for a wide range of plant parameter variations, requiring only one input: the desired closed-loop bandwidth.

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Wu, Kui Hua, Wei Sun, Jian Wang, Shen Quan Yang, Yi Qun Wang i Bo Li. "Design of the Three-Phase Photovoltaic Grid-Connected Inverter". Advanced Materials Research 986-987 (lipiec 2014): 1938–41. http://dx.doi.org/10.4028/www.scientific.net/amr.986-987.1938.

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Photovoltaic grid-connected power generation is the inevitable development trend of solar photovoltaic systems,grid inverter is an essential part of photovoltaic grid-connected power generation. With the developed three phase current type PWM inverter device as the research object, and symmetry rules sampling method is applied to the inverter, through the method combined by the computer simulation and experiment research, the device was verified by simulation and experimental .The results show that: This method could not only effectively reduce the DC side inductance volume of the current-mode PWM inverter , and it could make output AC currents sinusoidal and in phase with grid voltages, but also improve the efficiency of the system, it will be more suitable for photovoltaic grid-connected.

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Adityarini, Devi, Erma Prihastanti, Endah Dwi Hastuti i Nintya Setiari. "Mangrove Management Rhizophora mucronata Lamk. in Mangunharjo, Semarang City Based on Pollen Quality". Ecology, Environment and Conservation 28 (2022): 01–06. http://dx.doi.org/10.53550/eec.2022.v28i07s.001.

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Rhizophora mucronata is a type of mangrove that plays an important role in coastal life. Reproductivity of R. mucronata is influenced by environmental factors. This study aims to examine the effect of environmental conditions on pollen quality in terms of viability and germination. The sampling method used was purposive sampling from three stations and two different flowering phases (pre-anthesis and anthesis). Pollen quality was carried out by staining test using acetocarmine dye and germination test using Brewbaker and Kwack (BK) media. The data were then analyzed using analysis of variance. Based on differences in sampling stations, the highest pollen viability was recorded at Station II (91.25%), and the highest was in the preanthesis flowering phase (92.88%). The highest pollen germination was recorded at Station III (95.36%), and the lowest was in the pre-anthesis phase from Station I (87.41%). The results showed that the three different location two different flowering phase were still suitable for the growth of R. mucronata mangroves.

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Ebrahimpanah, Shahrouz, Qihong Chen, Liyan Zhang i Misbawu Adam. "Model Predictive Voltage Control with Optimal Duty Cycle for Three-Phase Grid-Connected Inverter". Journal of Control Science and Engineering 2019 (12.05.2019): 1–13. http://dx.doi.org/10.1155/2019/8951794.

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This paper proposes a model predictive voltage control (MPVC) strategy with duty cycle control for grid-connected three-phase inverters with output LCL filter. The model of the system is used to predict the capacitor filter voltage according to the future output current for each possible switching state at each sampling period. Then the cost function for each prediction is determined and the switching state is selected. In the proposed method, two voltage vectors are applied during one sampling interval to achieve better steady-state performance. Finally, the optimal duration of the nonzero voltage vector is defined based on the duty cycle optimization, which is vital to the control system. The proposed strategy offers a better reference tracking error with less THD in linear and nonlinear load situations. The effectiveness of the proposed method has been verified by MATLAB/Simulink and experimental results exhibit a better steady-state performance with less sampling frequency.

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Høier, R., C. R. Birkeland, R. Holmestad i K. Marthinsen. "Three-phase structure invariants and structure factors determined with the quantitative convergent-beam electron diffraction method". Acta Crystallographica Section A Foundations of Crystallography 55, nr 2 (1.03.1999): 188–96. http://dx.doi.org/10.1107/s0108767398008903.

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Quantitative convergent-beam electron diffraction is used to determine structure factors and three-phase structure invariants. The refinements are based on centre-disc intensities only. An algorithm for parameter-sensitive pixel sampling of experimental intensities is implemented in the refinement procedure to increase sensitivity and computer speed. Typical three-beam effects are illustrated for the centrosymmetric case. The modified refinement method is applied to determine amplitudes and three-phase structure invariants in noncentrosymmetric InP. The accuracy of the results is shown to depend on the choice of the initial parameters in the refinement. Even unrealistic starting assumptions and incorrect temperature factor lead to stable results for the structure invariant. The examples show that the accuracy varies from 1 to 10° in the electron three-phase invariants determined and from 0.5 to 5% for the amplitudes. Individual phases could not be determined in the present case owing to spatial intensity correlations between phase-sensitive pixels. However, for the three-phase structure invariant, stable solutions were found.

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Xu, Yongxiang, Hao Yan, Jibin Zou, Baochao Wang i Yunhui Li. "Zero Voltage Vector Sampling Method for PMSM Three-Phase Current Reconstruction Using Single Current Sensor". IEEE Transactions on Power Electronics 32, nr 5 (maj 2017): 3797–807. http://dx.doi.org/10.1109/tpel.2016.2588141.

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Pei, Yu Jie, Yun Shan Zhang, Jian Guo Xu, Jing Long Mu, Lei Zhang, Pin Dong, Bo Cong i Shu Han Wang. "Implementation of Single Phase Locked Loop Based on FPGA and its Application in SVC". Advanced Materials Research 986-987 (lipiec 2014): 1826–32. http://dx.doi.org/10.4028/www.scientific.net/amr.986-987.1826.

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Whereas three-phase phase locked loop could not get accurate phase position under three-phase unbalanced condition of the power grid, the design of single phase locked loop is implemented in the principle of single phase locked loop, based on FPGA technology. the paper explains design difficulties of single phase locked loop in detail, puts forward adaptive sampling scheme using single phase locked loop under variable frequency, increases accuracy of SVC sampling system. And tests response speed of phase locked loop via Real Time Digital Simulator for Power Systems (RTDS), through final verification in Fushun Lishizhai SVC Project, the design could meet system requirement for voltage phase accuracy.

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Tayebi, S. Milad, i Issa Batarseh. "Mitigation of Current Distortion in a Three-Phase Microinverter With Phase Skipping Using a Synchronous Sampling DC-Link Voltage Control". IEEE Transactions on Industrial Electronics 65, nr 5 (maj 2018): 3910–20. http://dx.doi.org/10.1109/tie.2017.2760864.

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Xu, Ying, i Tao Li. "Research on the Oil-Gas-Water Three-Phase Flow Experimental Apparatus". Advanced Materials Research 328-330 (wrzesień 2011): 2023–26. http://dx.doi.org/10.4028/www.scientific.net/amr.328-330.2023.

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The oil-gas-water three-phase flow experimental apparatus in key laboratory of process monitoring and control in Tianjin University is a set of indoor small experimental device, which can simulate oil wells, simulate the pipeline transport of multiphase flow and study the experiment of multiphase flow. The device includes energy power dynamic systems, measurement pipelines systems, multiphase flow test pipelines system, control valves, sampling and control system platform. The software of the control system is mixed programming between the configuration software MCGS and the Visual Basic.

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Larsen, Anders, i Kim Esbensen. "Principles of gas sampling: TOS with critical challenges". TOS Forum 2020, nr 10 (19.10.2020): 41. http://dx.doi.org/10.1255/tosf.126.

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Sampling and analysis of materials in the gas phase is not covered in general sampling standards and guides, due to the complex nature of the subject matter. Most gas-phase materials exist in the region from ambient temperatures (~300 K) to combustion temperatures typically around ~1200 K. Common to both temperature range margins, though predominantly for hot gases, is the fact that continuous reactions often take place in material that is moving at high speeds, presenting less than trivial challenges to conventional Theory of Sampling (TOS). The purposes of representative gas sampling are many, but three standard cases are presented, covering the most dominating scenarios met with in science, technology and industry.

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Kim, Jeongwoo, Yu Han, Shanshan Wang, Yihe Wang i Younghoon Cho. "A Current Reconstruction at Parallel Three Phase Inverters Using Two Current Sensors". Electronics 8, nr 2 (4.02.2019): 179. http://dx.doi.org/10.3390/electronics8020179.

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In this paper, a current restoration method which can be applied to three phase parallel interleaved inverters (TPPII) using two current sensors has been proposed. In the proposed current reconstruction method, the branch current and the phase current of the two phases of the TPPII are sampled concurrently at the peak and valley of the pulse width modulation (PWM) carrier using two hall-effect sensors. Then, the phase current of each inverter is reconstructed by analyzing the sensed current with the current conduction path information according to the switch state in the peak and valley of the PWM carrier. This paper additionally analyzes the characteristics of the offset occurring in the detection process of two current sensors and it proposes a compensation method to reduce the offset on-line. In order to at once reduce the offset of the three-phase recovery current caused by the DC offset of the sensor, a coordinate conversion method and a low pass are used. To verify the performance of the proposed current recovery method and real-time offset compensation method, a simulation using PSIM software was performed, and experiments were conducted using a three phase parallel inverter composed of insulated gate bipolar transistor (IGBT) modules. In particular, the AC offset that occurred in the sampling process during the experiment was analyzed and modeled, and it was reduced by simple calculation.

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Lv, Feng, T. Luan i C. H. Zhang. "The Design and Implementation of Three-Phase SPWM Based on DSP". Advanced Materials Research 301-303 (lipiec 2011): 1754–59. http://dx.doi.org/10.4028/www.scientific.net/amr.301-303.1754.

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This paper discusses the principle of SPWM, as well as its mathematical models, highlight introduce the generation principle of SPWM wave based on TI digital signal processor TMS320LF2407A. The formula and mathematical model are simplified by using the symmetric regular sampling method. Update the value of the program by comparing the look-up table, this method improves the operational efficiency, and reduces the error generation. The paper detailed analysis the configuration of each register in event manager module, and gives a critical interrupt subroutine. Through online simulation debugging, get the correct SPWM and the corresponding dead-time waveform.

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Zeng, Zhiyong, Xiaoliang Jin i Rongxiang Zhao. "Small-signal discrete-time modeling of digitally controlled three-phase PWM boost rectifier under balanced voltage". COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 36, nr 1 (3.01.2017): 18–47. http://dx.doi.org/10.1108/compel-03-2016-0113.

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Purpose The model for digitally controlled three-phase pulse width modulation (PWM) boost rectifiers is a sampled data model, which is different from the continuous time domain models presented in previous studies. The controller, which is tuned according to the model in continuous time domain and discretized by approximation methods, may exhibit some unpredictable performances and even result in unstable systems under some extreme situations. Consequently, a small-signal discrete-time model of digitally controlled three-phase PWM boost rectifier is required. The purpose of this paper is to provide a simple but accurate small-signal discrete-time model of digital controlled three-phase PWM boost rectifier, which explains the effect of the sampling period, modulator and time delays on system dynamic and improves the control performance. Design/methodology/approach Based on the Laplace domain analysis and the waveforms of up-down-count modulator, the small signal model of digital pulse width modulation (DPWM) in the Laplace domain is presented. With a combination of state-space average and a discrete-time modeling technique, a simplified large signal discrete time model is developed. With rotation transformation and feed-forward decoupling, the large-signal model is decoupled into a single input single output system with rotation transformation. Then, an integrated small signal model in the Laplace domain is constructed that included the time delay and modulation effect. Implementing the modified z-transform, a small-signal discrete-time model is derived from the integrated small signal model. Findings In a digital control system, besides the circuit parameters, the location of pole of open-loop transfer function is also related to system sampling time, affecting the system stability, and the time delay determines the location of the zero of open-loop transfer function, affecting the system dynamic. In addition to the circuit parameters discussed in previous literature, the right half plane (RHP) zero is also determined by the sampling period and the time delay. Furthermore, the corner frequency of the RHP zero is mainly determined by the sampling period. Originality/value The model developed in this paper, accounting for the effect of the sampling period, modulator and time delays on the system dynamic, give a sufficient insight into the behavior of the digitally controlled three-phase PWM rectifier. It can also explain the effect of sampling period and control delay time on system dynamic, accurately predict the system stability boundary and determine the oscillation frequency of the current loop in critical stable. The experimental results verify that the model is a simple and accurate control-oriented small-signal discrete-time model for the digitally controlled three-phase PWM boost rectifier.

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TSAI, SHAN-HO, FUGAO WANG i D. P. LANDAU. "TWO-DIMENSIONAL WANG–LANDAU SAMPLING OF AN ASYMMETRIC ISING MODEL". International Journal of Modern Physics C 20, nr 09 (wrzesień 2009): 1357–66. http://dx.doi.org/10.1142/s0129183109014424.

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We study the critical endpoint behavior of an asymmetric Ising model with two- and three-body interactions on a triangular lattice, in the presence of an external field. We use a two-dimensional Wang–Landau sampling method to determine the density of states for this model. An accurate density of states allowed us to map out the phase diagram accurately and observe a clear divergence of the curvature of the spectator phase boundary and of the derivative of the magnetization coexistence diameter near the critical endpoint, in agreement with previous theoretical predictions.

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Tang, Qipeng, Anwen Shen, Wuhua Li, Pan Luo, Min Chen i Xiangning He. "Multiple-Positions-Coupled Sampling Method for PMSM Three-Phase Current Reconstruction With a Single Current Sensor". IEEE Transactions on Power Electronics 35, nr 1 (styczeń 2020): 699–708. http://dx.doi.org/10.1109/tpel.2019.2913684.

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Carugati, Ignacio, Carlos M. Orallo, Patricio G. Donato, Sebastian Maestri, Jorge L. Strack i Daniel Carrica. "Three-Phase Harmonic and Sequence Components Measurement Method Based on mSDFT and Variable Sampling Period Technique". IEEE Transactions on Instrumentation and Measurement 65, nr 8 (sierpień 2016): 1761–72. http://dx.doi.org/10.1109/tim.2016.2552679.

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Gilmore, Christopher, Wei Dong i Gérard Bricogne. "A multisolution method of phase determination by combined maximization of entropy and likelihood. VI. The use of error-correcting codes as a source of phase permutation and their application to the phase problem in powder, electron and macromolecular crystallography". Acta Crystallographica Section A Foundations of Crystallography 55, nr 1 (1.01.1999): 70–83. http://dx.doi.org/10.1107/s0108767398007909.

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The use of error-correcting codes as a source of efficient designs of phase permutation schemes is described. Three codes are used, all taken from the Bricogne BUSTER program [Bricogne (1993). Acta Cryst. D49, 37–60]: the Hamming [7, 4, 3], the Nordström–Robinson (16, 256, 6) and the Golay [24, 12, 8] or its punctured [23, 12, 7] form. These are used in a maximum-entropy–likelihood phasing environment to carry out phase permutation of basis-set reflections instead of the usual quadrant permutation or magic integer approaches. The use of codes in this way inevitably introduces some errors in the phase choices, but for most structures this is not significant especially when the gain in sampling efficiency is considered. For example, the Golay [24, 14, 8] allows the permutation of 24 centric phases in such a way that only 4096 phase sets are produced instead of 224 = 16 777 216, and one of these sets has, at most, only four wrong phases. The method is successfully applied to three powder diffraction data sets of increasing complexity, and with increasing degrees of overlap {Mg3BN3, Sigma-2 ([Si64O128]\,\cdot\,4C10H17N) and the NU-3 zeolite}, a sparse electron diffraction data set for buckminsterfullerene, C60, and the small protein molecule crambin at 3 Å resolution where 42 reflections are phased with a U-weighted mean phase error of 58.5°.

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Hsu, Yung-Han, John A. Kershaw, Mark J. Ducey, Ting-Ru Yang i Haozhou Wang. "Sampling with probability proportional to prediction (3P sampling) using covariates derived from spherical images". Canadian Journal of Forest Research 51, nr 8 (sierpień 2021): 1140–47. http://dx.doi.org/10.1139/cjfr-2020-0498.

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Using a two-phase sampling approach with systematic selection of large samples of covariates followed by a sampling with probability proportional to prediction (3P sampling) process to subsample field measures of the parameters of interest can be an efficient design to sample larger forest areas. To assist in obtaining predictions for each sample plot consistently and rapidly, we propose using a 360° spherical camera. In this study, three covariates derived from spherical images were evaluated: (i) basal area (P[BA]); (ii) sum of squared heights per hectare (P[SHT]); and (iii) stem fraction (P[SF]). These covariates were used to estimate volume. Sample simulations showed no biases in volume estimates for any of the three covariates. Overall, P[SF] had the lowest standard error percentages across different simulated sample sizes (10% for five subsamples to 2.5% for 50 subsamples), even though it had the lowest correlations with field volume (correlation = 0.30–0.31). This may be a result of the relatively consistent stand conditions within the study site. Based on our results, standard errors of 5% were obtainable with measurement fractions of about 25% of the number of image-based predictions when using P[SF] or P[BA] and 75% when using P[SHT].

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Nurdiansa, Eko Saputra. "THE EFFECT OF THREE PHASE TECHNIQUE ON STUDENTS’ READING COMPREHENSION". Journal of Teaching English 4, nr 3 (9.09.2019): 303. http://dx.doi.org/10.36709/jte.v4i3.13959.

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The objective of the study is to know whether or not three phase technique has significant effect on students’ reading comprehension. The design of this study was quasi experimental research. The population of the study were students who were taking Reading 1 class in English study program at Halu Oleo University in academic year of 2016-2017. By employing purposive sampling technique the researcher chose class A as the sample of this study. Instrument of study was reading comprehension test in form of multiple choices questions. The result of this study confirmed that the teaching reading by using three phase reading technique could give significant effect on the students’ reading comprehension. Based on the Paired Sample Test, it was found that there was a significant difference of students’ reading comprehension score before and after they were given treatment by using three phase reading technique procedure in Reading 1 class with the significant degree of 0.013. Furthermore, there was also significant improvement in students' mean score (79.78). Therefore, the proposed hypothesis which stated “three phase reading technique has significant effect on students’ reading comprehension” was accepted. Keywords: Three Phase Technique, Reading Comprehension

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Wang, Ping, Dui Yuan Li, Da Rong Zhu i Guang Zhu. "Applying of FFT Algorithmic in Power Substation Microcomputer Monitoring System Based on DSP2407". Advanced Materials Research 753-755 (sierpień 2013): 2573–77. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.2573.

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In the detection substation microcomputer AC sampling system , monitor the three-phase voltagethree-phase current , power factor ,power online in real-time. This paper describes a FFT designing idea of the synchronous sampling in AC sampling from the substation monitoring system parameters .It provided sampling and calculation methods to apply DSP, MCU measurement of AC signal , details of the mathematical model of AC electrical parameters digital sampling, the introduction of schematic diagram of hardware processing sampling signal of FFT, comparison of the realization of the software and MATLAB simulation, thus obtained the correctness of this algorithm.

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Jun, Eun-Su, So-young Park i Sangshin Kwak. "Model Predictive Current Control Method with Improved Performances for Three-Phase Voltage Source Inverters". Electronics 8, nr 6 (3.06.2019): 625. http://dx.doi.org/10.3390/electronics8060625.

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In this paper, the model predictive current control (MPCC) method using two vectors has been proposed to control output currents of three-phase voltage source inverters (VSIs) with small current errors and current ripples. Also, the proposed method can reduce switching losses by applying the vector pre-selection technique to the MPCC for the VSI. The VSI generates seven voltage vectors to control the output currents, but the proposed method uses four available voltage vectors with one switch, which are classified by the vector pre-selection method clamping one leg and conducting the largest output current among the three legs to reduce the switching losses. In the proposed method, selecting two future voltage vectors among the four voltage vectors and dividing them in a future sampling period are determined by an optimization process. The proposed method results in the lower total loss, better total harmonic distortion (THD), and smaller current errors than the conventional method with half the sampling period of the proposed method due to the optimal process. Simulation and experimental results of the three-phase VSIs are presented in order to verify the effectiveness of the proposed method.

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Kang, Shou Qiang, Shan Shan Li, Shi Zheng i Di Wu. "The Design and Implementation of High Precision Three-Phase Sine-Wave Signal Generator". Applied Mechanics and Materials 543-547 (marzec 2014): 838–41. http://dx.doi.org/10.4028/www.scientific.net/amm.543-547.838.

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A design and implementation method of high precision three-phase sine-wave signal generator is proposed based on MCU and FPGA. For the traditional design method, direct analog synthesis method and phase locked loop (PLL) technology are used to design the signal generator. So the function, the precision and other aspects are inadequate. Aiming to the problem, a signal generator is designed based on direct digital frequency synthesis (DDS) technology. The MCU is used to control the peripheral devices and the frequency and phase control word can be obtained. The DDS module is achieved by EP4CE6E22C8 and the waveform lookup table addresses are outputted. The digital three-phase sine-wave data can be read from the lookup table. Through the three-way D/A converter and the amplifier circuit, the digital signal is converted to analog signal and the three-phase sinusoidal wave is outputted. The precision can be improved by increasing the sampling points, phase accumulator bits and D/A bits, and then, high precision three-phase sine-signal can be obtained and the adjustable frequency precision is 0.001.

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Gao, Yaping, Guo Chen, Xi Chen, Liangliang Ma, Tong Luo i Dongdong Xue. "An Optima Combination Method of Three-Frequency Real-Time Cycle Slip Detection for Non-Normal Ionospheric Variation Data". Mathematical Problems in Engineering 2022 (14.04.2022): 1–9. http://dx.doi.org/10.1155/2022/3964417.

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Linear combinations of triple-frequency help improve the performance of cycle slip detection for high-precision positioning using a single receiver; however, the position can be easily misjudged under ionospheric scintillation conditions or low sampling rates. We propose a method, which is developed specially for the datasets under ionospheric scintillation conditions or low sampling rates, to detect the triple-frequency cycle slips in real-time based on optimal linear combination coefficients and ionospheric range delay. Detection formulas are derived from the triple-frequency geometry-free code-phase combination, and ionospheric range delay is estimated by the wide lane combination. In addition, the principle used to select an optimal linear phase combination coefficient is derived, and the optimal linear coefficient suitable under high ionospheric activity conditions is provided. Finally, the data collected from self-build stations JYPS and NQ01 are used to test the performance of the method. The results demonstrate that the improved method can be used to detect all combinations of cycle slips in real-time, even under conditions of ionospheric scintillation or a sampling period exceeding 10 s.

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Groeneveld, J. C., i A. C. Cockcroft. "Potential of a trap-fishery for deep-water rock lobster Palinurus delagoae off South Africa". Marine and Freshwater Research 48, nr 8 (1997): 993. http://dx.doi.org/10.1071/mf97190.

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An experiment to investigate the potential of a trap-fishery for deep-water rock lobster Palinurus delagoae was conducted off the east coast of South Africa between 1994 and 1996. The 75–425 m depth interval between 27°S and 32°S was stratified according to depth and latitude, and three regions (North, Central and South) were sampled systematically over the three years. Sampling by commercial vessels operating long-lines and traps included an experimental phase (fixed fishing positions) and a commercial phase (no restriction on fishing location). Generalized linear models were used to investigate the influence of year, region, sampling phase, month and soak time. Sampling phase was significant, with traps set during the commercial phase catching more than those set in the experimental phase. The effect of soak time on catch rates was not significant. The almost-50% decrease in the combined abundance index combined with a marked decrease in mean lobster size over the study period suggests a relatively low fisheries potential for this species in South African waters; this may be attributable to the relative scarcity of suitable habitat in the area.

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Telleria-Allika, Xabier, Jose M. Mercero, Xabier Lopez i Jon M. Matxain. "Building machine learning assisted phase diagrams: Three chemically relevant examples". AIP Advances 12, nr 7 (1.07.2022): 075206. http://dx.doi.org/10.1063/5.0088784.

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In this work, we present a systematic procedure to build phase diagrams for chemically relevant properties by the use of a semi-supervised machine learning technique called uncertainty sampling. Concretely, we focus on ground state spin multiplicity and chemical bonding properties. As a first step, we have obtained single-eutectic-point-containing solid–liquid systems that have been suitable for contrasting the validity of this approach. Once this was settled, on the one hand, we built magnetic phase diagrams for several Hooke atoms containing a few electrons (4 and 6) trapped in spheroidal harmonic potentials. Changing the parameters of the confinement potential, such as curvature and anisotropy, and interelectronic interaction strength, we have been able to obtain and rationalize magnetic phase transitions flipping the ground state spin multiplicity from singlet (nonmagnetic) to triplet (magnetic) states. On the other hand, Bader’s analysis is performed upon helium dimers confined by spherical harmonic potentials. Covalency is studied using descriptors as the sign for Δ ρ( r C) and H( r C), and the dependency on the degrees of freedom of the system is studied, i.e., potential curvature ω2 and interatomic distance R. As a result, we have observed that there may exist a covalent bond between He atoms for short enough distances and strong enough confinement. This machine learning procedure could, in principle, be applied to the study of other chemically relevant properties involving phase diagrams, saving a lot of computational resources.

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Song, Pengyun, Huazhang Wang, Junyi Zhang, Yanghui Liu i Tao Deng. "Research on Phase Current Reconstruction for DPWM2 of Induction Motor Drive System Based on DC-Link Current Sampling". Machines 10, nr 11 (21.11.2022): 1104. http://dx.doi.org/10.3390/machines10111104.

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In order to reduce the switching loss and cost, as well as improve the reliability of the induction motor (IM) drive system, the technology involving the three-phase current reconstruction of 60° discontinuous pulse width modulation (DPWM2) is studied in this paper. According to the analysis of the switching state for DPWM2 in different sectors, the three-phase current can be constructed by sampling the voltage of the DC-link resistor. When the target voltage vector is located near the sector boundary or in the low-modulation area, the duration of the active vector in the sampling period is less than the voltage sampling time, which leads to measurement errors of the DC-link current. Therefore, on the basis of the switching state in different unmeasured areas, a time compensation method combining phase shifting and frequency reduction is proposed, and the expressions for comparing values are derived. Lastly, a simulation model and an experimental platform are established to validate the accuracy of the proposed method.

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42

Abbasi, Muhammad Abbas, Abdul Rashid Bin Husain i Hasan Alqaraghuli. "Modular Approach to Implement Model Predictive Control on Three Phase Voltage Source Inverter". International Journal of Power Electronics and Drive Systems (IJPEDS) 9, nr 2 (1.06.2018): 897. http://dx.doi.org/10.11591/ijpeds.v9.i2.pp897-904.

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<span>A modular abstraction is presented to implement model predictive control (MPC) on a three phase two level voltage source inverter to control its output current. Traditional ways of coded implementation do not provide insights into the complex nature of MPC; hence a more intuitive, logical and flexible approach for hardware implementation is conceptualized in the form of signal flow graphs (SFGs) for estimation, prediction and optimization. Simulation results show good performance of the approach and easier code generation for real time implementation. RL load is assumed for the inverter and the importance of choosing load inductance and sampling time ratio is emphasized for better control performance.</span>

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Wang, Meng, i Yanyan Shi. "An Improved Predictive Current Control Scheme for Three-phase Voltage Source Converters". Journal of Circuits, Systems and Computers 25, nr 11 (14.08.2016): 1650133. http://dx.doi.org/10.1142/s0218126616501334.

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For a fully digital control of PWM converters, considerable research has been done based on the predictive current control (PCC) scheme. However, it requires a large amount of calculation in the step of experimental implementation. Besides, when compared with the classical linear control scheme, the sampling interval of the PCC scheme must be shorter to obtain the same control performance for current. Due to this, a digital signal processor with excellent performance is required. This paper proposes an improved simplified model PCC scheme for three-phase PWM converters. The main objective is to simplify the PCC scheme. Also, the proposed control scheme is able to reduce the calculation time without affecting the performance. Simulations and experiments are carried out to investigate the presented novel predictive current control scheme. The results indicate that the three-phase PWM converter has excellent static and dynamic performance with the proposed scheme. Besides, the calculation time can be obviously shortened.

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Liu, Yiyang, Yang Zhao, Shuaihua Yan, Chunhe Song i Fei Li. "A Sampling-Based Algorithm with the Metropolis Acceptance Criterion for Robot Motion Planning". Sensors 22, nr 23 (26.11.2022): 9203. http://dx.doi.org/10.3390/s22239203.

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Motion planning is one of the important research topics of robotics. As an improvement of Rapidly exploring Random Tree (RRT), the RRT* motion planning algorithm is widely used because of its asymptotic optimality. However, the running time of RRT* increases rapidly with the number of potential path vertices, resulting in slow convergence or even an inability to converge, which seriously reduces the performance and practical value of RRT*. To solve this issue, this paper proposes a two-phase motion planning algorithm named Metropolis RRT* (M-RRT*) based on the Metropolis acceptance criterion. First, to efficiently obtain the initial path and start the optimal path search phase earlier, an asymptotic vertex acceptance criterion is defined in the initial path estimation phase of M-RRT*. Second, to improve the convergence rate of the algorithm, a nonlinear dynamic vertex acceptance criterion is defined in the optimal path search phase, which preferentially accepts vertices that may improve the current path. The effectiveness of M-RRT* is verified by comparing it with existing algorithms through the simulation results in three test environments.

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Yingwen, Long, i Sun Yuhong. "A novel filter for three-phase power factor correction voltage feedback loop under heavy DC voltage ripple condition". Indian Journal of Power and River Valley Development 70, nr 9&10 (10.06.2021): 156. http://dx.doi.org/10.18311/ijprvd/2020/27947.

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THD and the amplitude balance of three-phase input current are an important index for the performance of three-phase power factor correction (PFC). In general, when the hardware and the load of three-phase PFC are confirmed, the THD and amplitude balance of three-phase input current mainly depend on voltage and current feedback loop of PFC. Firstly, this paper designs the traditional voltage and current feedback loop for three-phase PFC according to traditional small signal theory. Secondly, this paper studies the designing difficulty of large dc voltage ripple for PFC voltage controller and puts forward a new dc voltage ripple filter which can eliminate the ac component of sampling dc bus voltage. Finally, this paper proposes a novel filter with dc voltage ripple frequency adaption function to copy with the frequency variety of the voltage ripple caused by the change of the output inverter frequency. With the help of the proposed algorithm the distortion of three-phase 3 input current reference decreases rapidly, therefore, the low THD and good amplitude balance of three phase input current will be achieved.

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Onyango, Ronald, Brian Oduor i Francis Odundo. "Mean Estimation of a Sensitive Variable under Nonresponse Using Three-Stage RRT Model in Stratified Two-Phase Sampling". Journal of Probability and Statistics 2022 (22.04.2022): 1–14. http://dx.doi.org/10.1155/2022/4530120.

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The present study addresses the problems of mean estimation and nonresponse under the three-stage RRT model. Auxiliary information on an attribute and variable is used to propose a generalized class of exponential ratio-type estimators. Expressions for the bias, mean squared error, and minimum mean squared error for the proposed estimator are derived up to the first degree of approximation. The efficiency of the proposed estimator is studied theoretically and numerically using two real datasets. From the numerical analysis, the proposed generalized class of exponential ratio-type estimators outperforms ordinary mean estimators, usual ratio estimators, and exponential ratio-type estimators. Furthermore, the efficiencies of the mean estimators are observed to decrease with an increase in the sensitivity level of the survey question. As the inverse sampling rate and nonresponse rate go up, so does the efficiency of the mean estimators, which makes them more accurate.

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Tsamatsoulis, Dimitris. "Impact of the Sampling Period on the Design of Digital PID Controllers". International Journal of Energy 15 (21.11.2021): 92–97. http://dx.doi.org/10.46300/91010.2021.15.14.

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The impact of the sampling period on the parameterization of a digital PID controller in the frequency domain is attempted using three different digital approximations of the integral action. The controller is implemented in the industrial process of regulation of the cement sulphates in the cement mill outlet. The maximum sensitivity, Ms, has been utilized as a main robustness criterion. For the same Ms, proportional and differential gain, a rise of the sampling period leads to a decrease of the integral gain ki for all the three approximations. For the same sampling period, the function between proportional and integral gain differs for the three approximations studied. If the design satisfies two criteria simultaneously, maximum sensitivity and phase margin in the current study, then the permissible PID gains zone becomes narrower.

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Roberts, Lyle E., Robert L. Ward, Craig Smith i Daniel A. Shaddock. "Coherent Beam Combining Using an Internally Sensed Optical Phased Array of Frequency-Offset Phase Locked Lasers". Photonics 7, nr 4 (28.11.2020): 118. http://dx.doi.org/10.3390/photonics7040118.

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Coherent beam combining can be used to scale optical power and enable mechanism-free beam steering using an optical phased array. Coherently combining multiple free-running lasers in a leader-follower laser configuration is challenging due to the need to measure and stabilize large and highly dynamic phase differences between them. We present a scalable technique based on frequency-offset phase locking and digitally enhanced interferometry to clone the coherence of multiple lasers without the use of external sampling optics, which has the potential to support both coherent and spectral beam combining, and alleviates issues of voltage wrapping associated with actuating feedback control using electro-optic modulators. This technique was demonstrated experimentally using a tiled-aperture optical phased array in which the relative output phase of three free-running lasers was stabilized with an RMS output phase stability of λ/104.

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Sarjan, M., Kisman, Anikmatullah, M. Windarningsih, A. Jihadi, P. D. Permana i T. Chitra. "Attack intensity of pest in the vegetative phase of Atlantic potato variety in three different altitudes". IOP Conference Series: Earth and Environmental Science 913, nr 1 (1.11.2021): 012009. http://dx.doi.org/10.1088/1755-1315/913/1/012009.

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Abstract Abstract.Potato plants are grown well in the highlands and have the potential to grow at different altitudes. One of the challenges in growing potatoes is pest attack during plantations, especially during the vegetative phase. The study aims to determine the attack intensity of potato pests on Atlantic variety at three different altitudes. This study was conducted in the Sembalun District, East Lombok, in three different locations, namely Sajang Village (at ca. 900 m asl), SembalunBumbung Village (at ca.1000 m asl), and SembalunLawang Village (at ca.1200 m asl) from March to June 2021. The plantations were maintained according to the standard maintenance of potato plantation farmers in Sembalun, and data was collected on a two-week basis. The research method used was an experimental method based on a Randomized Block Design (RBD). The sampling of potato plants was done using systematic random sampling. The results showed that the highest attack intensity of pests in the vegetative phase was observed nine weeks after planting, where the plants were suitable for the foliar pest. Altogether, potato plantation in SembalunBumbung had the highest attack intensity than in SembalunLawang and Sajang village. Further research is needed to examine the resistance of several varieties of potato in different altitudes and different seasons to attack the intensity of pests.

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Purba, Anita, i Semaria Eva Elita Girsang. "Developing Think Talk Write Strategy on Students’ English Literation Capability". Budapest International Research and Critics Institute (BIRCI-Journal): Humanities and Social Sciences 4, nr 1 (23.02.2021): 1374–84. http://dx.doi.org/10.33258/birci.v4i1.1764.

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This study aims to determine the effect of developing Think Talk Write (TTW) Strategy in increasing literation capability of English text for 4th semester students of the 2019/2020 academic year of English Study Program, Education Faculty (FKIP) - Simalungun University (USI). The development of the TTW Strategy consists of three phases, namely Think, Talk and the Writing Phase. These three phases are the independent variables of the study, while the dependent variable is literation capability. The research was conducted for 30 students. The sampling technique used saturated sampling technique. The type of data used is primary data. Data were analysed using multiple linear regression analysis method. The results of the analysis show that the Think, Talk and Writing Phases have a positive and significant effect on increasing students’ literation capability in English text, both partially and simultaneously. Thus, it can be concluded that the development of the TTW Strategy has a positive and significant effect in improving students' literation capability.

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