Journal articles: 'Bases de cycles minimum'

1

Bradshaw, Zachary, and Richard H. Hammack. "Minimum cycle bases of direct products of graphs with cycles." Ars Mathematica Contemporanea 2, no. 1 (June 22, 2009): 101–19. http://dx.doi.org/10.26493/1855-3974.77.3d2.

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Mehlhorn, Kurt, and Dimitrios Michail. "Minimum cycle bases." ACM Transactions on Algorithms 6, no. 1 (December 2009): 1–13. http://dx.doi.org/10.1145/1644015.1644023.

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Xu, Mei. "Cycle Bases Structure of out Planar Graphs on the Projective Plane in Mechanics Engineering." Applied Mechanics and Materials 312 (February 2013): 745–48. http://dx.doi.org/10.4028/www.scientific.net/amm.312.745.

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In this paper we investigate the cycle base structure of 2-connected graphs on the projective plane and show the minimum cycle bases of 2-connected outer planar graph G in the case of ew (G) 5. Then give a proof about the one-one property between the minimum cycle bases and the shortest no contractible cycles.

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Hellmuth, Marc, Philipp-Jens Ostermeier, and Peter F. Stadler. "Minimum cycle bases of lexicographic products." Ars Mathematica Contemporanea 5, no. 2 (March 22, 2012): 223–34. http://dx.doi.org/10.26493/1855-3974.172.8a7.

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Berger, Franziska, Peter Gritzmann, and Sven de Vries. "Minimum Cycle Bases for Network Graphs." Algorithmica 40, no. 1 (May 28, 2004): 51–62. http://dx.doi.org/10.1007/s00453-004-1098-x.

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Stadler, Peter F. "Minimum cycle bases of Halin graphs." Journal of Graph Theory 43, no. 2 (May 13, 2003): 150–55. http://dx.doi.org/10.1002/jgt.10111.

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Ren, Han, and Mo Deng. "Minimum cycle bases of graphs on surfaces." Discrete Mathematics 307, no. 22 (October 2007): 2654–60. http://dx.doi.org/10.1016/j.disc.2006.11.020.

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Liu, Tsung-Hao, and Hsueh-I. Lu. "Minimum cycle bases of weighted outerplanar graphs." Information Processing Letters 110, no. 21 (October 2010): 970–74. http://dx.doi.org/10.1016/j.ipl.2010.08.005.

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9

Horton, Joseph D., and Franziska Berger. "Minimum cycle bases of graphs over different fields." Electronic Notes in Discrete Mathematics 22 (October 2005): 501–5. http://dx.doi.org/10.1016/j.endm.2005.06.092.

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Carrasco, V. M. S., H. Hayakawa, C. Kuroyanagi, M. C. Gallego, and J. M. Vaquero. "Strong evidence of low levels of solar activity during the Maunder Minimum." Monthly Notices of the Royal Astronomical Society 504, no. 4 (April 24, 2021): 5199–204. http://dx.doi.org/10.1093/mnras/stab1155.

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ABSTRACT The Maunder Minimum (MM) was a period of prolonged solar activity minimum between 1645 and 1715. Several works have identified a significant number of problematic spotless days in the MM included in existing data bases. We have found a list of exact spotless (in the second half of 1709) and spot days (January and August 1709) provided by Johann Heinrich Müller. We computed the most probable value and upper/lower limits of the active day fraction (ADF) from Müller's data using the hypergeometrical probability distribution. Our sample is not strictly random because Müller recorded observations in consecutive days when he observed sunspots. Therefore, our result represents an upper threshold of solar activity for 1709. We compared this result with annual values of the ADF calculated for the Dalton Minimum and the most recent solar cycles. We concluded that, although 1709 is one of the most active years in the MM, it was less active than most years both in the Dalton Minimum and in the most recent solar cycles. Therefore, the solar activity level estimated in this work for 1709 represents robust evidence of low solar activity levels in the MM.

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11

Rizzi, Romeo. "Minimum Weakly Fundamental Cycle Bases Are Hard To Find." Algorithmica 53, no. 3 (October 27, 2007): 402–24. http://dx.doi.org/10.1007/s00453-007-9112-8.

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12

Kavitha, Telikepalli, Kurt Mehlhorn, and Dimitrios Michail. "New Approximation Algorithms for Minimum Cycle Bases of Graphs." Algorithmica 59, no. 4 (May 20, 2009): 471–88. http://dx.doi.org/10.1007/s00453-009-9313-4.

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Amaldi, Edoardo, Leo Liberti, Francesco Maffioli, and Nelson Maculan. "Algorithms for finding minimum fundamental cycle bases in graphs." Electronic Notes in Discrete Mathematics 17 (October 2004): 29–33. http://dx.doi.org/10.1016/j.endm.2004.03.009.

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14

Hammack, Richard. "Minimum cycle bases of direct products of complete graphs." Information Processing Letters 102, no. 5 (May 2007): 214–18. http://dx.doi.org/10.1016/j.ipl.2006.12.012.

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15

Fan, Xujiao, Yong Xu, Xue Su, and Jinhuan Wang. "Finding Cut-Edges and the Minimum Spanning Tree via Semi-Tensor Product Approach." Journal of Systems Science and Information 6, no. 5 (November 5, 2018): 459–72. http://dx.doi.org/10.21078/jssi-2018-459-14.

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Abstract Using the semi-tensor product of matrices, this paper investigates cycles of graphs with application to cut-edges and the minimum spanning tree, and presents a number of new results and algorithms. Firstly, by defining a characteristic logical vector and using the matrix expression of logical functions, an algebraic description is obtained for cycles of graph, based on which a new necessary and sufficient condition is established to find all cycles for any graph. Secondly, using the necessary and sufficient condition of cycles, two algorithms are established to find all cut-edges and the minimum spanning tree, respectively. Finally, the study of an illustrative example shows that the results/algorithms presented in this paper are effective.

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16

Giampapa, Mark S. "Stellar cycles: general properties and future directions." Proceedings of the International Astronomical Union 7, S286 (October 2011): 257–67. http://dx.doi.org/10.1017/s1743921312004954.

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AbstractWe discuss the general properties of stellar cycles with emphasis on their amplitudes as a function of stellar parameters, particularly those stellar characteristics relevant to dynamo-driven magnetic activity. We deduce an empirical scaling relation between cycle frequency and differential rotation based on previously established empirical relations. We also compare the recent Cycle 23 to cycles in solar-type stars. We find that the extended minimum of Cycle 23 resembled in its Ca II H & K emission at minimum the mean levels of activity seen in stars with no cycles.

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Mbitu, Elisabeth Tansiana, and Seng-Chi Chen. "Designing Limit-Cycle Suppressor Using Dithering and Dual-Input Describing Function Methods." Mathematics 8, no. 11 (November 6, 2020): 1978. http://dx.doi.org/10.3390/math8111978.

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This paper described a method to design a limit-cycle suppressor. The dithering technique was used to eliminate self-sustained oscillations or limit cycles. Otherwise, the Dual Input Describing Function (DIDF) method was applied to design dither parameters and analyze the existence of limit cycles. This method was done in a nonlinear system with relay nonlinearity using three standard dither signals, namely sine, triangle, and square waves. The aim of choosing varying dithers was to investigate the effect of dither shapes and the minimum amplitude required for the quenching strategy. First, the possibility and amplitude of limit cycles were determined graphically on the DIDF curve. Then, the minimum amplitude of dither was calculated based on the DIDF analysis. Finally, a simulation was built to verify the analytical work using a digital computer. The simulation results were related to the analysis results. It was evident that the dithering technique is a simple way to suppress limit cycles in a nonlinear system. This paper also presented that dither is an amplitude function, and square-wave dither has the minimum amplitude to quench limit cycles.

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18

Ma, Deng Ju, and Han Ren. "Minor and minimum cycle bases of a 3-connected planar graph." Acta Mathematica Sinica, English Series 25, no. 4 (March 25, 2009): 649–56. http://dx.doi.org/10.1007/s10114-009-7160-5.

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19

Doerr, Carola, G. Ramakrishna, and Jens M. Schmidt. "Computing Minimum Cycle Bases in Weighted Partial 2-Trees in Linear Time." Journal of Graph Algorithms and Applications 18, no. 3 (2014): 325–46. http://dx.doi.org/10.7155/jgaa.00325.

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20

Liberti, Leo, Edoardo Amaldi, Francesco Maffioli, and Nelson Maculan. "Mathematical models and a constructive heuristic for finding minimum fundamental cycle bases." Yugoslav Journal of Operations Research 15, no. 1 (2005): 15–24. http://dx.doi.org/10.2298/yjor0501015l.

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The problem of finding a fundamental cycle basis with minimum total cost in a graph arises in many application fields. In this paper we present some integer linear programming formulations and we compare their performances, in terms of instance size, CPU time required for the solution, and quality of the associated lower bound derived by solving the corresponding continuous relaxations. Since only very small instances can be solved to optimality with these formulations and very large instances occur in a number of applications, we present a new constructive heuristic and compare it with alternative heuristics.

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21

Reich, Alexander. "Minimum strictly fundamental cycle bases of planar graphs are hard to find." Discrete Applied Mathematics 205 (May 2016): 150–59. http://dx.doi.org/10.1016/j.dam.2015.12.001.

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22

Al-Taie, Dr Ghassan A. "Influence of Heating Rates and Residual Monomer on Dimensional Changes of Acrylic Resin Denture Base." Mustansiria Dental Journal 5, no. 4 (January 25, 2018): 393–97. http://dx.doi.org/10.32828/mdj.v5i4.562.

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Background: Most of spaces between the denture base and master cast produced by shrinkage of the base material during polymerization and by the difference in coefficient of thermal expansion of the cast and acrylic resin. The aim of this study is to evaluate the effect of the different heating rates and the presence of residual monomer on the accuracy different curing denture base by recording the gap space between the cast and the dentureMaterials and methods: 18 maxillary edentulous stone cast were prepared then divided into three main groups, denture bases were constructed. In Group A, using Biostar plates (free of monomer) in the pressure champers. In group B, using short curing cycle while group C, using long curing cycle . The gap space between the cast and denture base was recorded using traveling microscope measuring device.Results: Biostar curing resin (group A) showed significantly the highest dimensional changes among groups (short and long curing resins). There was no significant difference between group B ( short curing resin) and group C (long curing resin). The lowest gap space values were obtained in long curing resin. All samples showed maximum discrepancy in mid palatal reign and minimum dimensional changes at the crest of ridge. Minimum gap space values were shown in the canine reign for record bases cured with short and long curing cycles, while minimum gap space values were shown in the posterior palatal seal for record base cured with Biostar machine.Conclusion: The dimensional changes of record bases mainly depend on the amount of heat applied during processing rather than the amount of residual monomer. Greater distortion was shown in record base processed by Biostar machine (Free of monomer), while the least distortion in record base processed by long curing cycle. All samples showed maximum discrepancy in the mid palatal region and minimum dimensional changes at the crest of ridge.

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23

Cui, Jiahui, Nguyen Duc Van, Feng Zhang, and Yukio Hama. "Evaluation of Applicability of Minimum Required Compressive Strength for Cold Weather Concreting Based on Winter Meteorological Factors." Materials 15, no. 23 (November 28, 2022): 8490. http://dx.doi.org/10.3390/ma15238490.

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In this paper, we evaluated the applicability of the minimum required compressive strength for cold weather concreting based on winter meteorological factors. In this study, a compressive strength test, dynamic elastic modulus test, hydration degree test, underwater weighing test, and freeze–thaw test were performed to investigate the effect of compressive strength development at early ages on frost resistance of concrete. In particular, the ASTM equivalent number of cycles (CyASTM−sp) of various locations was estimated based on winter meteorological factors. The results of experiments showed that the frost resistance of concrete at early ages increases with increased compressive strength. The relative dynamic modulus of elasticity of concrete of 5.0 MPa showed that it can be maintained above 90% within 18 freeze–thaw cycles. In addition, the CyASTM−sp results showed that a compressive strength of 5.0 MPa can protect concrete from early age frost damage in all investigated locations, indicating that a compressive strength of 5.0 MPa is the minimum required for safe and reliable cold weather concreting. However, for concrete structures subjected to repeated freeze–thaw cycles, it is necessary to select a higher compressive strength value according to the construction condition.

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Nascimento, Luan de Oliveira, Vanderley Borges dos Santos, Sandra Bezerra da Silva, Joaes Alves da Silva Pereira, Eldevan Alves da Silva, Antonia Fabiana Barros de Lima, Josimar Batista Ferreira, Lidiane Assis Silva, and Dheme Rebouças de Araujo. "Morphoagronomic characterization and production gain after two mass selection cycles in Nawa Sheki landraces maize originated from the Western Brazilian Amazon." March 2023, no. 17(03):2023 (March 3, 2023): 299–307. http://dx.doi.org/10.21475/ajcs.23.17.03.p3831.

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Intensive breeding and artificial selection of the desired traits in maize landraces through domestication have created modern maize, which needs a great technological contribution for optimal productive development. However, the narrowing of the genetic bases of maize made it difficult for traditional farmers to access productive genetic material that maintains the genotypic and phenotypic diversity capable of ensuring productive sustainability. Thus, objective of the study was to evaluate the variability and production gain in morphoagronomic characters of Nawa Sheki landraces maize after two mass selection cycles. The work was carried out in the experimental area of the Federal University of Acre, where two cycles of mass selection were applied on variety Nawa Sheki, in periods 2018/2019 and 2019/2020. The characteristics evaluated were: plant height, ear insertion height, ear length, ear diameter, number of rows of grains, number of grains per row, ear mass and grain mass. Data were submitted to descriptive analysis, with presentation of the histogram of frequency, asymmetry, kurtosis and Shapiro-Wilk test for the general population in both cycles. For the selected population, the following were obtained: mean, coefficient of variation, amplitude, minimum and maximum values and population variance in each cycle. The genetic parameters were selection differential for both cycles, production gain with selection and realized heritability of the first cycle. The choice of individuals in both cycles of mass selection was based on the ranking of the best values of the evaluated characteristics. The two cycles of mass selection provided high variability in the traits with the presence of superior phenotypes. Still, mass selection stabilized values for plant height, ear insertion height, followed by production gains for number of grains per row and ear mass.

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Zhang, Bin, Benjamin Ducharne, Bhaawan Gupta, Gael Sebald, Daniel Guyomar, and Jun Gao. "Experimental sea wave energy extractor based on piezoelectric Ericsson cycles." Journal of Intelligent Material Systems and Structures 29, no. 6 (September 26, 2017): 1102–12. http://dx.doi.org/10.1177/1045389x17730917.

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Recycling ambient energies with electric generators instead of employing batteries with limited lifespans has motivated a large scientist community over two decades. Sea waves exhibit a large energy density. The amount of energy that could be extracted from the sea waves is very high. This work describes a technique of sea wave energy extraction based on a piezoelectric conversion and an analogy with thermodynamic Ericsson loops. By synchronizing external electric field to the maximum and the minimum of the sea wave mechanical stress excitations, the piezoelectric material dielectric hysteresis loop area is increased corresponding to the maximum of the energy available. In this article, technical solutions are proposed for the in site deployment of the proposed technique (maximum and minimum detection, external electric field source synchronization). Experimental measuring benches have been developed to monitor the sea wave mechanical excitation and to determine precisely the energy-harvesting potential. Adequate dielectric hysteresis model is proposed to numerically determine the best configuration (frequency, amplitude) of electric field to impose. Even if the Ericsson technique requires external electronic devices, the weak consumption of such components allows a large enhancement of the amount of energy extracted compared to a basic piezo element conversion.

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Buccino, A. P., L. Sraibman, P. M. Olivar, and F. O. Minotti. "An application of a solar-type dynamo model for ε Eridani." Monthly Notices of the Royal Astronomical Society 497, no. 3 (August 20, 2020): 3968–75. http://dx.doi.org/10.1093/mnras/staa1908.

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ABSTRACT During the last decade, the relation between activity cycle periods and stellar parameters has received special attention. The construction of reliable registries of activity reveals that solar-type stars exhibit activity cycles with periods from few years to decades and, in some cases, long and short activity cycles coexist suggesting that two dynamos could operate in these stars. In particular, ε Eridani is an active young K2V star (0.8 Gyr), which exhibits short and long-term chromospheric cycles of ∼3 and ∼13-yr periods. Additionally, between 1985 and 1992, the star went through a broad activity minimum, similar to the solar Maunder Minimum state. Motivated by these results, we found in ε Eridani a great opportunity to test the dynamo theory. Based on the model developed in Sraibman & Minotti, in this work we built a non-linear axisymmetric dynamo for ε Eridani. The time series of the simulated magnetic field components near the surface integrated in all the stellar disc exhibits both the long and short activity cycles with periods similar to the ones detected from observations and also time intervals of low activity that could be associated with the broad Minimum. The short activity cycle associated with the magnetic reversal could be explained by the differential rotation, while the long cycle is associated with the meridional mass flows induced by the Lorentz force. In this way, we show that a single non-linear dynamo model derived from first principles with accurate stellar parameters could reproduce coexisting activity cycles.

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Marliana, Eka, Ismail Ismail, and Moch Yanuar Ramadhan. "ANALISA DAN REDESAIN SPROCKET ASSEMBLY CONVEYOR RAKE C2 DI STASIUN KETEL PG NGADIREJO." ELEMEN : JURNAL TEKNIK MESIN 8, no. 2 (August 18, 2022): 77–85. http://dx.doi.org/10.34128/je.v8i2.167.

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Abstract. In the Ngadirejo sugar plant, sprocket shaft on the east C2 rake conveyor at the boiler station always failure every year. This conveyor is used for the process of fuel dregs supply at the boiler station. In this research, the analysis of failure and fatigue with the finite element method in Ansys will be carried out. The material analyzed is HQ705 with static loading. The analysis carried out includes static structural analysis and fatigue analysis on the sprocket shaft. Based on this analysis, found that the maximum displacement is 0.001163 m, the maximum equivalent stress is 71.8 MPa, the minimum life is 17.237 cycles, the maximum shear stress is 38.44 MPa, the minimum safety factor is 0.557744. The failure in the FEM analysis results in accordance with the actual failure location. The redesign process was carried out with HQ709 material, with this material the minimum life value is 50539 cycles.

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Senthilkumar, P., Kasmaruddin Che Hussin, Mohamad Zamhari Tahir, T. Padmapriya, and S. V. Manikanthan. "An Interference Optimization – Induced Electrical Turbine Fault Prediction and Analysis Method." WSEAS TRANSACTIONS ON POWER SYSTEMS 18 (December 5, 2023): 293–300. http://dx.doi.org/10.37394/232016.2023.18.30.

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Predicting electrical turbine faults is decisive for consistent operation and power generation output. Based on the operative cycles of the electrical turbine, the faults are predicted to prevent power generation interruptions. This paper introduces an Interference Optimization-based Fault Prediction Method (IO-FPM) for serving smooth operation purposes. In this method, the inferred optimization using classifier tree learning is induced for segregating the operating cycles of the turbine. The maximum and minimum threshold conditions for turbine operation using resistance and magnitude of the blades are accounted for each operation cycle. The classifier performs segregation based on low and high thresholds for predicting failure cycles. Such cycles are altered using pre-maintenance intervals and mechanical fault diagnosis at an early stage. This prevents turbine failure regardless of external influencing factors.

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Thomas, Simon, Mathew Owens, Mike Lockwood, and Chris Owen. "Decadal trends in the diurnal variation of galactic cosmic rays observed using neutron monitor data." Annales Geophysicae 35, no. 4 (July 17, 2017): 825–38. http://dx.doi.org/10.5194/angeo-35-825-2017.

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Abstract. The diurnal variation (DV) in galactic cosmic ray (GCR) flux is a widely observed phenomenon in neutron monitor data. The background variation considered primarily in this study is due to the balance between the convection of energetic particles away from the Sun and the inward diffusion of energetic particles along magnetic field lines. However, there are also times of enhanced DV following geomagnetic disturbances caused by coronal mass ejections or corotating interaction regions. In this study we investigate changes in the DV over four solar cycles using ground-based neutron monitors at different magnetic latitudes and longitudes at Earth. We divide all of the hourly neutron monitor data into magnetic polarity cycles to investigate cycle-to-cycle variations in the phase and amplitude of the DV. The results show, in general, a similarity between each of the A < 0 cycles and A > 0 cycles, but with a phase change between the two. To investigate this further, we split the neutron monitor data by solar magnetic polarity between times when the dominant polarity was either directed outward (positive) or inward (negative) at the northern solar pole. We find that the maxima and minima of the DV changes by, typically, 1–2 h between the two polarity states for all non-polar neutron monitors. This difference between cycles becomes even larger in amplitude and phase with the removal of periods with enhanced DV caused by solar wind transients. The time difference between polarity cycles is found to vary in a 22-year cycle for both the maximum and minimum times of the DV. The times of the maximum and minimum in the DV do not always vary in the same manner between A > 0 and A < 0 polarity cycles, suggesting a slight change in the anisotropy vector of GCRs arriving at Earth between polarity cycles. Polar neutron monitors show differences in phase between polarity cycles which have asymptotic directions at mid-to-high latitudes. All neutron monitors show changes in the amplitude of the DV with solar polarity, with the amplitude of the DV being a factor of 2 greater in A < 0 cycles than A > 0 cycles. In most cases the change in timing of the maximum /minimum is greatest with the stations' geomagnetic cut-off rigidity shows little variation in the DV phase with latitude. We conclude that the change in the DV with the dominant solar polar polarity is not as simple as a phase change, but rather an asymmetric variation which is sensitive to the neutron monitor's asymptotic viewing direction.

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Abdelmalek, Azizi, Benamara Jamal, Ismaili Moulay Chrif, and Talbi Mohammed. "Cycles of reduced ideals and class number of pure cubic number field." MATHEMATICA 63 (86), no. 1 (May 25, 2021): 13–22. http://dx.doi.org/10.24193/mathcluj.2021.1.02.

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31

Marzuki, Abdul Gafur. "Developing Speaking Skill through Oral Report in an EFL Class in Indonesia." Al-Ta lim Journal 24, no. 3 (December 17, 2017): 243–54. http://dx.doi.org/10.15548/jt.v24i3.330.

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This Classroom Action Research aims at developing students’ speaking skill through the application of oral report technique. This research is conducted collaboratively in three cycles in which researcher acts as a lecturer while his collaborator acts as an observer and each cycle consists of two meetings. Data of this research is attained from two main sources namely qualitative and quantitative data. The data shows that In preliminary study, 35.5% students could answer questions given by researcher through interview but the achievement score shows that 13.3% students could fulfill the minimum criteria of achievement. The minimum criterion of achievement is 60. At cycle I, 37% students could participate in oral report and 24.4% students could fulfill the minimum criteria of achievement. At cycle II, 51.1% students could participate in oral report and 42.2% students could fulfill the minimum criteria of achievement. The last is 75% students could fulfill the minimum criteria of achievement from 86.6% students who participated in oral report at cycle III from 45 students. Furthermore, the highest score obtained by student from each of cycles present that in preliminary study is 70 whereas 72.5 at cycle I, 85 at cycle II, and 90 at cycle III. Based on the findings of this research, it can be inferred that the application of oral report technique can develop students’ speaking skill in using English

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Alpkaya, Alican Tuncay, and Senay Mihcin. "Sensitivity Analysis of Wear on Metal-On-Metal Bearing Couples via Verification of Numeric and Analytic Methods." Hittite Journal of Science and Engineering 11, no. 2 (June 30, 2024): 57–67. http://dx.doi.org/10.17350/hjse19030000332.

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Wear mechanism is important since it leads to revisions in Total Hip Replacement (THR) surgeries. Contact pressure plays an important role in wear mechanisms and needs to be investigated in detail to obtain more accurate wear predictions to understand the wear performance of the implant in the design stage. This study proposes a methodology for verification of contact pressure and pressure distribution via numeric and analytic methods to be used in wear calculations. Based on Hertz’s contact theory, the contact pressure and the contact area ae calculated in the analytical method. The results are compared to the numeric method’s results obtained from the finite element method. The linear and volumetric wear rates of bearing couples’ surfaces were estimated by Archard’s wear equation. The effect of design parameters on pressure such as head radius, cup thickness, material combination of bearing couples, coating film material, and film thickness are investigated in this study using the proposed methodology. The minimum error between the analytical and numerical results was 0.24% for 28 mm of head diameter, while the maximum error was 11.79 % for 48- mm of head diameter. The minimum contact pressure values were obtained from 48- mm of head radius at a half contact angle of 190 (degrees) in FEM and Hertz calculations, respectively. The maximum linear wear rate was calculated at 0.0026 mm/Mc at a 1- mm cup thickness, while minimum linear wear rate was 0.0022 mm/Mc at a 10- mm cup thickness in the numeric method. The maximum survival cycles of coating materials rate were 31847 cycles for the Stainless-steel coated cup with 500 μm of coating thickness, while the minimum cycles was 2359 cycles for the Ti64 coated cup surface with 100 μm of coating thickness. It is concluded that the most important design parameters are the cup thickness and the material combinations since they have a significant effect on the contact pressure and the contact area. This study provides a verification methodology for the parametric sensitivity analysis before experimental validations. The methodology utilized in this study could be utilized by designers while optimizing the design parameters to minimize the wear.

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Qu, Yi. "Towards Innovation of German Teaching via IoT Assistance and Virtual Classroom." Journal of Combinatorial Mathematics and Combinatorial Computing 119, no. 1 (March 31, 2024): 245–54. http://dx.doi.org/10.61091/jcmcc119-24.

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The penetration of virtual classroom teaching into German teaching is the presentation of teaching innovation in the information age. In this work, we explore the necessity of applying virtual classroom teaching in German classrooms and the effective strategies of German teaching innovation in virtual classrooms, to provide some suggestions for the reform of German teaching. First, the GPS trajectories are transformed into a sequence of hotspot regions using the spatiotemporal properties of GPS points. Then, a sequential pattern mining algorithm of asynchronous cycles with multiple minimum supports based on pattern growth is adopted, and the sequential patterns of asynchronous cycles are deeply recursively mined according to the multiple minimum supports. Experiments show that the proposed IoT-assisted teaching scheme can effectively integrate equipment resources, mine spatiotemporal information, and help students and teachers establish a new educational method of integrating space and land. Compared with the baseline, it can fully exploit the characteristics of German.

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Gao, Yang, Changhong Liu, Yuan Liang, Sadegh Kouhestani Hamed, Fuwei Wang, and Bo Bi. "Minimizing Energy Consumption and Powertrain Cost of Fuel Cell Hybrid Vehicles with Consideration of Different Driving Cycles and SOC Ranges." Energies 15, no. 17 (August 25, 2022): 6167. http://dx.doi.org/10.3390/en15176167.

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Hydrogen consumption is an important performance indicator of fuel cell hybrid vehicles (FCHVs). Previous studies have investigated fuel consumption minimization both under different driving cycles and using various power management strategies. However, different constrains on battery state of charge (SOC) ranges can also affect fuel consumption dramatically. In this study, we develop a power-source sizing model based on the Pontryagin’s Minimum Principle (PMP) to minimize the fuel consumption of FCHVs, considering different driving cycles (i.e., FTP-72 and US06) and SOC ranges (conservative 50–60% and aggressive 20–80%). The different driving cycles and SOC ranges present the real-world circumstances of driving FCHVs to some extent. Fuel consumptions are compared both under different driving cycles and using different SOC ranges. The simulation results show an effective power size map, with outlines of an ineffective sizing zone and an inefficient sizing zone based on vehicle performance requirements (e.g., maximum speed and acceleration) and fuel consumption, respectively. Based on the developed model, an optimal power-source size map can be determined while minimizing both fuel consumption and powertrain cost as well as considering different driving cycles and SOC ranges.

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Moriya, Toru, Hiroko Miyahara, Motonari Ohyama, Masataka Hakozaki, Mirei Takeyama, Hirohisa Sakurai, and Fuyuki Tokanai. "A Study of Variation of the 11-yr Solar Cycle before the onset of the Spoerer Minimum based on Annually measured 14C Content in tree Rings." Radiocarbon 61, no. 6 (November 22, 2019): 1749–54. http://dx.doi.org/10.1017/rdc.2019.123.

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ABSTRACTProxy-based observations of solar activity in the past have revealed long-term variations, such as the Gleissberg cycle (~88 yr), de Vries cycle (~200 yr), and the Hallstatt cycle (~2000 yr). Such long-term variations of solar activity sometimes cause the disappearance of sunspots for several decades. Currently, solar activity is becoming weaker, and there is a possibility that another long-term sunspot minimum could occur. However, the detailed mechanism of the weakening in solar activity is unknown, and the prediction of solar activity is ambiguous. In this study, we investigate the transitions of solar cycle length before the onset of the Spoerer Minimum, the longest grand minimum in the past 2000 yr. We measured the 14C content in an asunaro tree (Thujopsis dolabrata) excavated at Shimokita Peninsula from 1368–1420 CE using the compact AMS system at Yamagata University. It is found that the solar cycle lengthened to be 14–16 yr from 2 cycles before the onset of the Spoerer Minimum.

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Garishin, Oleg K., Vladimir V. Shadrin, Alexander P. Voznyakovskii, and Anna Yu Neverovskaya. "Cyclic tests of viscoelastic highly elastic materials according to the ‘Nested cycles’ program." Вестник Пермского университета. Физика, no. 3 (2024): 40–49. http://dx.doi.org/10.17072/1994-3598-2024-3-40-49.

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Experimental studies of the viscoelastic properties of elastomeric nanocomposites based on styrene-butadiene rubber and binary filler (carbon black and detonation nanodiamonds) were carried out. In order to most effectively identify the features of the viscoelastic behavior of these materials (which depend not only on the deformation but also on its rate), we used a special test program with ‘nested cycles’ developed at the Institute of Continuous Media Mechanics of the Ural Branch of the Russian Academy of Sciences. During testing, the sample is subjected to uniaxial cyclic loading with the amplitude and rate of deformation decreasing at each step. At the beginning and end of the cycle (i.e., at minimum and maximum cyclic deformations), the grips of the tensile testing machine are stopped for a fixed period of time to measure relaxation dependences. Such an approach allows obtaining the maximum amount of information about both viscous and elastic properties of the tested material in one experiment. The mass content of nanodiamond particles in all samples was the same (7 parts by mass), the proportion of carbon black varied (23, 33 and 43 parts by mass). The equilibrium stress-strain curves (which are very important for theorists for constructing the governing rheological equations) were calculated based on experimental relaxation dependences (stress versus time). An analysis of stress-strain loading curves made it possible to obtain concentration dependences of mechanical characteristics such as maximum and minimum cyclic stresses, initial, minimum and maximum moduli for the first loading curve (elastic properties), hysteresis of cyclic losses (viscous properties at different loading rates). The Mullins softening effect (a drop in elastomer stiffness after the first loading cycle) was also studied.

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Carrasco, V. M. S., J. M. Vaquero, and A. J. P. Aparicio. "Assessing the Evolution of Solar Cycle 25: A Weak-moderate Cycle." Research Notes of the AAS 8, no. 7 (July 17, 2024): 183. http://dx.doi.org/10.3847/2515-5172/ad62fb.

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Abstract This note aims to analyze the evolution of the sunspot number for Solar Cycle 25, updating our previous findings on this topic. We compare daily, monthly and 13 months smoothed sunspot numbers for Solar Cycle 25 with those from previous cycles since mid-18th century (Solar Cycles 1–25). The highest daily, monthly and 13 months smoothed values for Solar Cycle 25 are significantly lower than the mean and median values considering all cycles. In particular, Solar Cycle 25 ranks 17th in terms of the highest 13 months smoothed sunspot number at this point in the cycle. Based on current data and the progression toward its maximum, we conclude that Solar Cycle 25 is likely to be a weak to moderate cycle, consistent with our earlier analyses. In addition, we find that Solar Cycles 13, 14, and 16 have the most similar behavior to that of Solar Cycle 25. Assuming a cycle length for Solar Cycle 25 similar to those of the above cycles, we estimate that the minimum of Solar Cycle 26 will be in 2030–2031.

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Kilpua, E. K. J., C. O. Lee, J. G. Luhmann, and Y. Li. "Interplanetary coronal mass ejections in the near-Earth solar wind during the minimum periods following solar cycles 22 and 23." Annales Geophysicae 29, no. 8 (August 30, 2011): 1455–67. http://dx.doi.org/10.5194/angeo-29-1455-2011.

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Abstract. In this paper we examine the occurrence rates and properties of interplanetary coronal mass ejections (ICMEs) and solar activity levels during the minima following solar cycle 22 (January 1995–December 1997) and 23 (January 2007–April 2010) minima using observations from the OMNI data base. Throughout the minimum following cycle 22 the CME and ICME rates roughly tracked each other, while for the minimum following cycle 23 they diverged. During the minimum after solar cycle 23, there were large variations in the streamer belt structure. During the lowest activity period of cycle 23 (based on sunspot numbers), the ICME rate was about four times higher than during a similar activity period of cycle 22. We propose that this relatively high ICME rate may be due to CME source regions occurring at lower heliolatitudes and due to equatoward deflection of slow and weak CMEs originating from the mid- and high-heliolatitudes. The maximum magnetic fields of the ICMEs identified during the minimum following cycle 23 were ~30 % lower and their radial widths were ~15 % lower compared to the ICMEs observed during the minimum following solar cycle 22. The weak and small ICMEs may result from intrinsically weak CMEs and/or they may represent stronger CMEs that are encountered far away from the center.

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Shibaev, I. G. "Estimation of the Average Values of the Wolf Numbers of Cycles of the Dalton Minimum Based on the Characteristics of Reliable Cycles of a Series." Геомагнетизм и аэрономия 63, no. 3 (May 1, 2023): 403–8. http://dx.doi.org/10.31857/s001679402210025x.

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The source material for the number of Wolf numbers is both archival records of disparate observationsand regular observatory observations. Many researchers rely on a series of Wolf numbers, includingrestored data of archival records, although the properties and characteristics of the restored and reliable partsof the series differ significantly. The parameters of the restored part itself are also contradictory. Naturally,matching the properties of the reconstructed and reliable series will smooth the contradictions and expandthe array of more reliable data. Taking the relationship between the characteristics of significant cycles intoaccount, options for group correction of the average values of cycles I–IX are presented. Since local dataresiduals play a lesser role when comparing extended fragments, by relying on the integral estimates of thesefragments (without detailing the conditions for their formation) we obtained more weighted interval estimates.The parameters of intervals (groups of cycles) of a reliable series serve as the basis for correction.

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Ayres, Thomas. "The Cycles of Alpha Centauri: Double Dipping of AB." Astronomical Journal 166, no. 5 (November 1, 2023): 212. http://dx.doi.org/10.3847/1538-3881/acfef5.

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Abstract In mid-2023, the Sunlike dwarfs of nearby α Centauri (HD 128620 (“A”): G2 V; HD 128621 (“B”): K1 V; hereafter “AB”) coincidentally both entered coronal (T ≈ 1–3 MK) low states in their long-term X-ray cycles, as captured by the Chandra Observatory and its High Resolution Camera (HRC-I). The assessment benefited from a sensitivity degradation model for HRC-I based on a “check star,” the F subgiant Procyon (α Canis Minoris A; HD 61421: F5 IV–V), further validated by Hubble Space Telescope time series of the Fe xii 1241.985 Å and 1349.396 Å coronal forbidden lines (T ≈ 1.6 MK) of all three stars. The AB starspot-cycle periods noted previously, 19 and 8 yr, appear to be holding. These deviate substantially from the 11 yr solar example, despite only modest differences in the stellar properties. The new cycle-minimum L X/L BOL of α Cen A is similar to that of the previous minimum observed by Chandra in 2005–2010, and close to solar-MIN X-ray levels in 2009 and 2019, with implications for the “basal” coronal flux of low-activity early G stars. The recent α Cen B X-ray MIN is similar to that in 2016 but higher than an earlier one in 2007–2009. Significantly, the B X-ray minima (in L X/L BOL) are comparable to the solar Cycle 24 maximum, suggesting plentiful starspots at the B-cycle MIN (contrary to the solar case). Tangentially, the current AB low states favor Doppler-reflex detections of planets, as opposed to the coronal high states, when elevated chromospheric activity can add nuisance signals to radial velocity time series.

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Stangl, Martin, and Ulrich Foelsche. "Challenges of Using Historical Aurora Observations for the Reconstruction of Solar Activity before the 19th Century, Especially during and near the Maunder Minimum." Atmosphere 15, no. 8 (August 6, 2024): 941. http://dx.doi.org/10.3390/atmos15080941.

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In order to complement gaps in the surveillance of solar activity in historical times, various proxies are used to reconstruct past solar cycles and long-term maxima and minima of solar activity, the most famous being the Maunder Minimum (MM), which is usually defined to span the period between the years 1645 and 1715. We explain the problems within existing data bases and call upon trying to find the original sources of Schröder, since his aurorae catalog spans the whole MM and contradicts what has been deduced from more used compilations. We take a critical look at the proposed source-critical scheme introduced by Neuhäuser and Neuhäuser and show it to be counterproductive because it largely ignores the source situation, i.e., the scientific understanding of the reporters of times long past and their intentions. While historical sunspot and aurora reports can be useful to fine-tune our knowledge of solar activity in times before the onset of systematical surveillances, they should not be used as an index of solar activity, since they cannot be quantitatively expressed due to the non-scientific manner of the reports and ambiguous wording. Reconstructions based on cosmogenic isotopes are significantly preferable for establishing the level of solar activity in the past. The conclusions reached by this review should be regarded as a caution against expecting important conclusions to emerge from low quality data.

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Nurhuda, Nurhuda, Ruqiah Ganda Putri Panjaitan, and Wartiningsih Wartiningsih. "Enhancing learning outcomes through problem-based learning in plant reproduction topics." Jurnal Pendidikan Informatika dan Sains 13, no. 1 (June 30, 2024): 1–8. http://dx.doi.org/10.31571/saintek.v13i1.7408.

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This study aims to enhance students' learning outcomes on the topic of plant reproduction in 9th-grade classes through the application of the Problem-Based Learning (PBL) model. This study used a Classroom Action Research (CAR) methodology with two learning cycles to improve student learning outcomes on the topic of plant reproduction in 9th grade. In the first cycle, the average learning outcome score was 72, which is below the minimum mastery criterion (<75). Observations were made by an observer regarding the students' learning activities and the teaching process conducted by the teacher during the first cycle. These observations served as a reference for the subsequent learning cycle. In the second cycle, there was an improvement in learning outcomes, with an average score of 85, indicating that students, on average, had achieved the minimum mastery criterion (minimum mastery score 75). The classroom action research involved four stages: planning, implementation, observation, and reflection. The results show that the gradual application of the PBL model progressively improved students' learning outcomes on the topic of plant reproduction.

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Efimenko, V. M. Efimenko, and V. G. Lozitsky. "PREDICTION OF THE AMPLITUDE OF 25 TH SOLAR CYCLE USING THE RATE OF INCREASE OF SOLAR ACTIVITY." Odessa Astronomical Publications 35 (December 14, 2022): 95–98. http://dx.doi.org/10.18524/1810-4215.2022.35.268201.

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A prediction of the amplitude of the 25th cycle of solar activity is proposed based on the analysis of data on 24 previous solar cycles, which relate to the statistical relationship between the rate of increase in the number of sunspots in the phase of the growth curve and the amplitude of the cycle. It turned out that the forecasting result depends on which section of the growth curve is taken as the basis for forecasting, as well as whether all 24 cycles are taken into account, or only the odd ones. The prediction result is also affected by the initial assumption about monotonicity or non-monotonicity of the growth phase. A comparison of the rates of sunspot growth in different parts of the growth phase of different cycles shows that the current cycle #25 does not show early signs of non monotonic growth similar to those observed in the 24th cycle. It was concluded that, most likely, the maximum smoothed number of sunspots in the 25th cycle W max (25) should be equal to 185 ± 18 units in the new system, which corresponds to the average power of the solar cycle, with the implementation of the Hnievyshev-Ohl rule. However, if cycle #25 will still have a non-monotonic curve of the growth phase, similar to such a curve in the previous cycle #24, then W max (25) » 130. With such parameters of this cycle, there are no signs of approaching the deep minimum of the age cycle in the middle 21st century. This does not exclude the fact that this deep age minimum can occur suddenly and sharply immediately after the 25th cycle, as was the case, for example, in the Dalton minimum.

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Santos, Jenifer, Luis Alfonso Trujillo-Cayado, Francisco Carrillo, María Luisa López-Castejón, and María Carmen Alfaro-Rodríguez. "Relation between Droplet Size Distributions and Physical Stability for Zein Microfluidized Emulsions." Polymers 14, no. 11 (May 28, 2022): 2195. http://dx.doi.org/10.3390/polym14112195.

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Zein, a subproduct of the food industry and a protein, possesses limited applications due to its high hydrophobic character. The objective of this research was to investigate the influence of homogenization pressure and cycles on the volumetric mean diameter (D4,3), span values, and Turbiscan Stability Index (TSI) using the response surface methodology for microfluidized emulsions containing zein as a unique stabilizer. Results showed that homogenization pressure seems to be the most influential parameter to obtain enhanced physical stability and droplet size distributions, with the optimum being 20,000 psi. Interestingly, the optimum number of cycles for volumetric diameter, span value, and TSI is not the same. Although a decrease of D4,3 with number of cycles is observed (optimum three cycles), this provokes an increase of span values (optimum one cycle) due to the recoalescence effect. Since physical stability is influenced by D4,3 and span, the minimum for TSI is observed at the middle level of the cycles (2 cycles). This work highlights that not only volumetric diameter, but also span value must be taken into consideration in order to obtain stable zein emulsions. In addition, this study wants to extend the limited knowledge about zein-based emulsions processed with a Microfluidizer device.

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Nurlaelah, Nurlaelah. "Problem-Based Learning Method for Improving the Learning Achievement of Students." Edunesia: Jurnal Ilmiah Pendidikan 4, no. 2 (February 13, 2023): 447–57. http://dx.doi.org/10.51276/edu.v4i2.330.

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The issue with this study is the low levels of student learning outcomes and learning activities in the sample IPS2 individuals. The objective of this project is to raise student learning outcomes and active learning achievement in social studies. PTK, or classroom action research, is the term used to describe this sort of study. Planning, action implementation, observation, and reflection are all phases of research. The information used in this study came from watching student learning outcomes and activities in Social Sciences 2 courses. According to the recapitulation data, the first cycle's average percentage of learning activities was 63.8%, and the second cycle's average percentage was 89.34%. This demonstrates an increase in student learning activities. In cycles I and II, respectively, the average student learning outcome was 42.22% and 71.04%. This demonstrates that social studies 2 student learning outcomes have improved. The minimum completeness score (71.04%) is obtained, according to the recapitulation of learning activities and student learning outcomes using problem-based learning techniques. Thus, applying the problem-based learning method can improve learning outcomes and learning activities of class C1 IPS2 students of the PGMI FAI-UMI Makassar Study Program.

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Agee, Ernest M., Emily Cornett, and Kandace Gleason. "An Extended Solar Cycle 23 with Deep Minimum Transition to Cycle 24: Assessments and Climatic Ramifications." Journal of Climate 23, no. 22 (November 15, 2010): 6110–14. http://dx.doi.org/10.1175/2010jcli3831.1.

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Abstract The extended length of solar cycle 23 and the associated deep quiet period (QP) between cycles 23 and 24 have been examined using the international sunspot record from 1755 to 2010. This study has also introduced a QP definition based on a (beginning and ending) mean monthly threshold value of less than 10 for the sunspot number. Features addressed are the length and intensity of cycle 23, the length of the QP and the associated number of spotless days, and the respective relationships between cycle intensity, length, and QP. The length of cycle 23 (153 months) is second only to cycle 4 (164 months), with an average of 132.5 months for the 11-yr cycle. The length of the QP between cycles 23 and 24 ranks eighth, extending from October 2005 through November 2009 (but subject to continued weakness in cycle 24). The number of spotless days achieved within this QP was 751 (and for all days within the transition from cycle 23 to cycle24, a record number of 801 spotless days had been observed through May 2010). Shortcomings of solar-convection-model predictions of sunspot activity and intensity are also noted, including the failure in the initial predictions of cycle-24 onset. The relevance of an extended quiet solar period and the potential reduction of total solar irradiance (TSI) are also discussed, both in the context of climate-model simulations of future climate change as well as with regard to future satellite measurements of TSI.

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Chiu, Fu-Chien. "Resistance Switching Characteristics in ZnO-Based Nonvolatile Memory Devices." Advances in Materials Science and Engineering 2013 (2013): 1–5. http://dx.doi.org/10.1155/2013/362053.

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Bipolar resistance switching characteristics are demonstrated in Pt/ZnO/Pt nonvolatile memory devices. A negative differential resistance or snapback characteristic can be observed when the memory device switches from a high resistance state to a low resistance state due to the formation of filamentary conducting path. The dependence of pulse width and temperature on set/reset voltages was examined in this work. The exponentially decreasing trend of set/reset voltage with increasing pulse width is observed except when pulse width is larger than 1 s. Hence, to switch the ZnO memory devices, a minimum set/reset voltage is required. The set voltage decreases linearly with the temperature whereas the reset voltage is nearly temperature-independent. In addition, the ac cycling endurance can be over 106switching cycles, whereas, the dependence of HRS/LRS resistance distribution indicates that a significant memory window closure may take place after about 102 dc switching cycles.

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Braga, Mónica, and Javier Marenco. "Facets based on cycles and cliques for the acyclic coloring polytope." RAIRO - Operations Research 54, no. 6 (September 16, 2020): 1863–74. http://dx.doi.org/10.1051/ro/2019098.

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A coloring of a graph is an assignment of colors to its vertices such that any two vertices receive distinct colors whenever they are adjacent. An acyclic coloring is a coloring such that no cycle receives exactly two colors, and the acyclic chromatic number χA(G) of a graph G is the minimum number of colors in any such coloring of G. Given a graph G and an integer k, determining whether χA(G) ≤ k or not is NP-complete even for k = 3. The acyclic coloring problem arises in the context of efficient computations of sparse and symmetric Hessian matrices via substitution methods. In a previous work we presented facet-inducing families of valid inequalities based on induced even cycles for the polytope associated to an integer programming formulation of the acyclic coloring problem. In this work we continue with this study by introducing new families of facet-inducing inequalities based on combinations of even cycles and cliques.

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Carslaw, D. C. "On the changing seasonal cycles and trends of ozone at Mace Head, Ireland." Atmospheric Chemistry and Physics Discussions 5, no. 4 (August 15, 2005): 5987–6011. http://dx.doi.org/10.5194/acpd-5-5987-2005.

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Abstract. A seasonal-trend decomposition technique based on a locally-weighted regression smoothing (Loess) approach has been used to decompose monthly ozone concentrations at Mace Head (Ireland) into trend, seasonal and irregular components. The trend component shows a steady increase from 1990–2004, which is confirmed by statistical testing that shows that ozone concentrations at Mace Head have increased at the p=0.06 level by 0.18±0.04 ppb yr−1. By considering different air mass origins using a trajectory analysis, it has been possible to separate air masses into "polluted" and "unpolluted" origins. The seasonal-trend decomposition technique confirms the different seasonal cycles of these air mass origins with unpolluted air mass maxima in April and polluted air mass maxima in July/August. A detailed consideration of the seasonal component reveals different behaviour depending on the air mass origin. For baseline unpolluted air arriving at Mace Head there has been a gradual increase in the seasonal amplitude, driven by a declining summertime component. The amplitude of the seasonal component of baseline air is controlled by a maximum in April and a minimum in July. For polluted air mass trajectories, there was a substantial reduction in the amplitude of the seasonal component from 1990–1997. However, post-1997 results indicate that the seasonal amplitude in polluted air masses arriving at Mace Head is increasing. Furthermore, there has been a shift in the months controlling the size of the seasonal amplitude in polluted air from a maximum in May and minimum in January in 1990 to a maximum in April and a minimum in July by 2001. These results indicate that the characteristics of baseline air are becoming more important in polluted air masses arriving at this location.

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Carslaw, D. C. "On the changing seasonal cycles and trends of ozone at Mace Head, Ireland." Atmospheric Chemistry and Physics 5, no. 12 (December 20, 2005): 3441–50. http://dx.doi.org/10.5194/acp-5-3441-2005.

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Abstract. A seasonal-trend decomposition technique based on a locally-weighted regression smoothing (Loess) approach has been used to decompose monthly ozone concentrations at Mace Head (Ireland) into trend, seasonal and irregular components. The trend component shows a steady increase from 1990–2004, which is confirmed by statistical testing which shows that ozone concentrations at Mace Head have increased at the p=0.06 level by 0.18±0.04 ppb yr−1. By considering different air mass origins using a trajectory analysis, it has been possible to separate air masses into "polluted" and "unpolluted" origins. The seasonal-trend decomposition technique confirms the different seasonal cycles of these air mass origins with unpolluted air mass maxima in April and polluted air mass maxima in July/August. A detailed consideration of the seasonal component reveals different behaviour depending on the air mass origin. For baseline unpolluted air arriving at Mace Head there has been a gradual increase in the seasonal amplitude, driven by a declining summertime component. The amplitude of the seasonal component of baseline air is controlled by a maximum in April and a minimum in July. For polluted air mass trajectories, there was a substantial reduction in the amplitude of the seasonal component from 1990–1997. However, post-1997 results indicate that the seasonal amplitude in polluted air masses arriving at Mace Head is increasing. Furthermore, there has been a shift in the months controlling the size of the seasonal amplitude in polluted air from a maximum in May and minimum in January in 1990 to a maximum in April and a minimum in July by 2001. This finding suggests that there has been a steadily decreasing influence of polluted air masses arriving from Europe. These air masses have therefore increasingly taken on the attributes of baseline air.

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Journal articles on the topic 'Bases de cycles minimum'

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