Journal articles on the topic 'Frequency jump'
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Jurdi, Doureige. "Intraday Jumps, Liquidity, and U.S. Macroeconomic News: Evidence from Exchange Traded Funds." Journal of Risk and Financial Management 13, no. 6 (June 5, 2020): 118. http://dx.doi.org/10.3390/jrfm13060118.
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This paper uses two highly liquid S&P 500 and gold exchange-traded funds (ETFs) to evaluate the impact of liquidity and macroeconomic news surprises on the frequency of observing intraday jumps. It explicitly addresses market microstructure noise-induced biases in realized estimators used in jump detection tests and applies non-parametric intraday jump detection tests. The results show a significant increase in trading costs and elevated levels of information asymmetry before observing jumps. Depth, resiliency, and trading activity are associated with the frequency of observing intraday jumps and cojumps. The ability of liquidity variables to predict intraday jumps persists after controlling for news surprises. Results show that intraday jump realizations affect the price discovery of ETFs.
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Janszky, J., and Y. Y. Yushin. "Squeezing via frequency jump." Optics Communications 59, no. 2 (August 1986): 151–54. http://dx.doi.org/10.1016/0030-4018(86)90468-2.
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LU, XINHONG, KEN-ICHI KAWAI, and KOICHI MAEKAWA. "ESTIMATING BIVARIATE GARCH-JUMP MODEL BASED ON HIGH FREQUENCY DATA: THE CASE OF REVALUATION OF THE CHINESE YUAN IN JULY 2005." Asia-Pacific Journal of Operational Research 27, no. 02 (April 2010): 287–300. http://dx.doi.org/10.1142/s0217595910002697.
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This paper analyzes the behavior of one-minute high-frequency time-series data of exchange rates for five currencies (Japanese Yen, Australian Dollar, Canadian Dollar, Euro, and Pound Sterling) against the US Dollar when the Chinese Yuan was revalued on July 21st, 2005. The data show the following distinctive features: (1) There is a large jump in the exchange rates time series at the time of the Yuan revaluation. (2) Large volatility in the returns of exchange rates is observed for a while after the jump. (3) There are many other jumps, possibly correlated, in each exchange rate time series. To capture these features we fit the following models to the data: (i) a univariate GARCH-Jump model with a large jump that is influential on volatility, and (ii) a bivariate GARCH-Jump model with correlated Poisson jumps. For comparison, we also estimate these GARCH models without the associated jumps. The model performance is evaluated based on Value-at-Risk (VaR).
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Yu, Chao, Jianxin Bi, and Xujie Zhao. "Modeling Financial Intraday Jump Tail Contagion with High Frequency Data Using Mutually Exciting Hawkes Process." Discrete Dynamics in Nature and Society 2020 (May 20, 2020): 1–10. http://dx.doi.org/10.1155/2020/7940647.
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Financial extreme jumps in asset price may propagate across stock markets and lead to the market-wide crashes, which severely threatens the stability of the financial system. In order to analyzing the contagion features of jump tail risk, this paper proposes a mutually exciting contagion model based on Hawkes process with intraday high frequency data. We use a simple two-stage method that first extracts the jump component nonparametrically from the high frequency data and then models the intraday jump tail using mutually exciting Hawkes process. Moreover, we take both the occurrence time and magnitude of jump into account in modeling the conditional intensity of Hawkes process. The proposed method is applied to the five-minute high frequency data of the Chinese stock market. The empirical results show that, for the two main Chinese stock markets, only background intensity is significant in the Shanghai stock market, while mutually exciting effect is significant in the Shenzhen stock market. Both the location and size of jump in the Shanghai stock market have significant stimulation to the next occurrences of jump in the Shenzhen stock market. Furthermore, the proposed model performs very well in predicting the future jump tail events.
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Chen, Guojin, Xiaoqun Liu, Peilin Hsieh, and Xiangqin Zhao. "Realized Jump Risk and Equity Return in China." Discrete Dynamics in Nature and Society 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/721635.
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We utilize the realized jump components to explore a new jump (including nonsystematic jump and systematic jump) risk factor model. After estimating daily realized jumps from high-frequency transaction data of the Chinese A-share stocks, we calculate monthly jump size, monthly jump standard deviation, and monthly jump arrival rate and then use those monthly jump factors to explain the return of the following month. Our empirical results show that the jump tail risk can explain the equity return. For the large capital-size stocks, large cap stock portfolios, and index, one-month lagged jump risk factor significantly explains the asset return variation. Our results remain the same even when we add the size and value factors in the robustness tests.
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Nkwoma, Inekwe John. "FUTURES-BASED MEASURES OF MONETARY POLICY AND JUMP RISK." Macroeconomic Dynamics 21, no. 2 (May 23, 2016): 384–405. http://dx.doi.org/10.1017/s1365100515000553.
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We estimate the effects of anticipated and unanticipated monetary policy changes on jump variation by employing high-frequency nonparametric jump detection methods. We find that anticipated changes in the Fed funds have no significant effect on jumps. In contrast, jump variation in the price of financial market data increases with monetary policy surprises. We document evidence of asymmetries in the response of jumps to monetary policy changes. Monetary policy surprises and positive changes in the Fed target rate induce increments in jumps. Similar results exist in the sector analysis. In addition, this study uncovers no evidence of endogenous response between jumps and monetary policy surprises.
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Riley, W. J. "Algorithms for frequency jump detection." Metrologia 45, no. 6 (December 2008): S154—S161. http://dx.doi.org/10.1088/0026-1394/45/6/s21.
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Dovonon, Prosper, Sílvia Gonçalves, Ulrich Hounyo, and Nour Meddahi. "Bootstrapping High-Frequency Jump Tests." Journal of the American Statistical Association 114, no. 526 (August 6, 2018): 793–803. http://dx.doi.org/10.1080/01621459.2018.1447485.
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Newhouse, Randal, Justine Minish, and Gary S. Collins. "Diffusion in Binary and Pseudo-Binary L12 Indides, Stannides, Gallides and Aluminides of Rare-Earth Elements as Studied Using Perturbed Angular Correlation of 111In/Cd." Defect and Diffusion Forum 323-325 (April 2012): 447–52. http://dx.doi.org/10.4028/www.scientific.net/ddf.323-325.447.
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Diffusional jumps can produce fluctuating electric field gradients at nuclei of jumping atoms. Using perturbed angular correlation of gamma rays (PAC), jumps of probe atoms cause nuclear quadrupole relaxation that can be fitted to obtain the mean jump frequency. An overview is given of the application of this approach to highly ordered intermetallic compounds having the L12(Cu3Au) crystal structure. New results are then presented for jump frequencies of111In/Cd probe atoms in pseudo-binary L12compounds of the forms In3(La1-xPrx) and (In1-xSnx)3La. For the mixed rare-earth system, jump frequencies are found to scale with composition between jump frequencies of the end-member phases In3La and In3Pr. However, for the mixed sp-element system, a large decrease in jump frequency is observed as Sn atoms substitute for In-atoms. This difference in behavior appears to depend on whether atomic disorder is on the diffusion sublattice (In-Sn substitution), as opposed to a neighboring sublattice (La-Pr substitution), whether or not there is a difference in diffusion mechanism between end-member phases, and/or whether or not there is a valence difference between the mixing atoms. All three conditions apply for only (In1-xSnx)3La.
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Lage, Stephanie, and Gary S. Collins. "Motion of Cadmium Tracer Atoms in Al11R3 Phases (R=La,Ce,Pr)." Defect and Diffusion Forum 289-292 (April 2009): 755–61. http://dx.doi.org/10.4028/www.scientific.net/ddf.289-292.755.
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Jump frequencies of Cd tracer atoms were measured in three phases having the orthorhombic Al11R3 structure, with R= La, Ce, or Pr. The structure has four inequivalent Al-sites and two inequivalent R-sites. 111In/Cd tracer atoms were observed to occupy several sites via the nuclear quadrupole interaction using perturbed angular correlation of gamma rays (PAC). Time-domain PAC spectra became damped as the temperature increased, which is attributed to nuclear relaxation caused by diffusional jumps of Cd tracer atoms leading to changes in orientations and/or magnitudes of electric field gradients (EFG’s). Maximum relaxations were observed near 770 K. A method is proposed for estimating the mean jump frequency at that temperature, giving a mean jump frequency w averaged over all sites of about 100 MHz. At still higher temperatures, damping decreased due to motional averaging, and the quadrupole perturbations evolved into unique signals having lower frequencies and corresponding in each phase to the averages of EFG tensors of all sites visited by the Cd tracer atoms. For Al11La3, the jump frequency at 1073 K was estimated to be 1.9 GHz. Such jump frequencies imply unusually high diffusivities in these phases.
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Štirn, Igor, Tjaša Brišnik, and Frane Erčulj. "VERTICAL LOAD ASSESSMENT IN MEN AND WOMEN 3X3 BASKETBALL." Kinesiologia Slovenica 28, no. 1 (May 26, 2022): 5–18. http://dx.doi.org/10.52165/kinsi.28.1.5-18.
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The purpose of the study was to evaluate the frequency and intensity of players' actions associated with jumping in the 3x3 basketball game, to compare these data between men's and women's teams, and to compare the data obtained with existing data from 5- on-5 basketball. Jumps during the five final games of the men's and women's national championship were recorded using the inertial measurement device VERT which was previously calibrated using force platform. The significance level set for the study was p ≤ 0.05. The number and height of jumps during the execution of jump shots from outside and inside the paint, lay -up shots, rebounds, and blocks were monitored. Female and male players performed 1.05 and 1.63 jumps per minute, respectively, in the 3x3 basketball game. For all jumps observed, the number of jumps was higher in males than in females, and the largest differences were found in jump shots inside the paint and jump when blocking (p < 0.05). The relative intensity of the jumps, expressed as a percentage of the maximum countermovement jump obtained before the play, showed that heights of just over 50% of the maximum were most common, except for the male players executing layup shots were the heights reached over 70% of the maximum. Comparing the results with previous studies, we summarize that the performance level of the athletes influences the frequency of actions. Low level teams executed fewer actions than high level teams, in parallel to their physical fitness.
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Lima, Ricardo Franco, José M. Palao, and Filipe Manuel Clemente. "Jump Performance During Official Matches in Elite Volleyball Players: A Pilot Study." Journal of Human Kinetics 67, no. 1 (July 5, 2019): 259–69. http://dx.doi.org/10.2478/hukin-2018-0080.
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AbstractThe purpose of this pilot study was to assess the types and intensity of the jumps that professional male volleyball players executed. Seven male elite volleyball players participated in this study. The sample was composed of 1599 jumps performed in 15 sets of five official matches of the regular season of a professional team. A descriptive pilot study design was implemented to analyze the types of jumps and jump heights by particular playing positions (outside hitters, setter, and middle blockers). The jump height was recorded using an inertial measurement device. No significant differences in the heights of jumps were found between the sets of the matches. Different players’ roles had different frequencies for different types of jumps and jump intensities. The data provide reference values of the type of jumps performed, their frequency, and intensity by particular playing positions in competition. The results confirm the need to individualize the practice and training of volleyball players according to the players’ roles. Extensive studies are needed to provide more information about repeated jump ability in volleyball players.
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Li, Jia, Viktor Todorov, and George Tauchen. "Jump factor models in large cross‐sections." Quantitative Economics 10, no. 2 (2019): 419–56. http://dx.doi.org/10.3982/qe1060.
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We develop tests for deciding whether a large cross‐section of asset prices obey an exact factor structure at the times of factor jumps. Such jump dependence is implied by standard linear factor models. Our inference is based on a panel of asset returns with asymptotically increasing cross‐sectional dimension and sampling frequency, and essentially no restriction on the relative magnitude of these two dimensions of the panel. The test is formed from the high‐frequency returns at the times when the risk factors are detected to have a jump. The test statistic is a cross‐sectional average of a measure of discrepancy in the estimated jump factor loadings of the assets at consecutive jump times. Under the null hypothesis, the discrepancy in the factor loadings is due to a measurement error, which shrinks with the increase of the sampling frequency, while under an alternative of a noisy jump factor model this discrepancy contains also nonvanishing firm‐specific shocks. The limit behavior of the test under the null hypothesis is nonstandard and reflects the strong‐dependence in the cross‐section of returns as well as their heteroskedasticity which is left unspecified. We further develop estimators for assessing the magnitude of firm‐specific risk in asset prices at the factor jump events. Empirical application to S&P 100 stocks provides evidence for exact one‐factor structure at times of big market‐wide jump events.
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Sayeed, Mohammad Abu, Mardi Dungey, and Wenying Yao. "High-frequency Characterisation of Indian Banking Stocks." Journal of Emerging Market Finance 17, no. 2_suppl (June 18, 2018): S213—S238. http://dx.doi.org/10.1177/0972652718777081.
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Using high-frequency stock returns in the Indian banking sector, we find that the beta on jump movements substantially exceeds that on the continuous component, and that the majority of the information content for returns lies with the jump beta. We contribute to the debate on strategies to decrease systemic risk, showing that increased bank capital and reduced leverage reduce both jump and continuous beta with slightly stronger effects for capital on continuous beta and stronger effects for leverage on jump beta. However, changes in these firm characteristics need to be large to create an economically meaningful change in beta.
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Pierce, Katherine, Julia Phillips, Paul Loprinzi, Matthew Jessee, Thomas Andre, Hannah Nelson, and Melinda Valliant. "Investigation into the accuracy of subjective load parameters in comparison to analytical load measurements in NCAA Division I women’s volleyball." Scientific Journal of Sport and Performance 2, no. 1 (December 22, 2022): 83–93. http://dx.doi.org/10.55860/algp9210.
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Monitoring athletes’ workload has become common practice in sports and differs depending on the sport’s physical demands. Within volleyball, an inertial measurement unit can be utilized to track the number of jumps performed by players. However, other methods of measuring jump frequency are needed for teams without access to this equipment. The purpose of this study was to determine if volleyball athletes can accurately predict the number of jumps performed after training and matches when given a perceptual scale and if player position, session rating of perceived exertion (sRPE), and perceived sets played affected the players’ accuracy. Less than half of the team’s jump count estimations (23.2%) were within 25 of the actual number of jumps and over half of the players’ responses (58%) were within 50 of the measured number of jumps. A generalized estimating equation (GEE) with a binary response was used to investigate the impact of position, sRPE, and sets played. Position was the only variable to have a significant impact on jump count accuracy. Based on these results, a perceptual scale could be useful in better understanding players’ jump counts following training, but number of jumps allotted to each jump range and position could impact accuracy.
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Shih, Po Jen, and Shang Hao Cai. "Frequency Response of Carbon Nanotube Probes during Tapping Mode of Atomic Force Microscopy." Applied Mechanics and Materials 378 (August 2013): 466–71. http://dx.doi.org/10.4028/www.scientific.net/amm.378.466.
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The dynamic behaviors of carbon nanotube probes applied in Atomic Force Microscope measurement are of interest in advanced nanoscalar topography. In this paper, we developed the characteristic equations and applied the model analysis to solve the eigenvalues of the microcantilever and the carbon nanotube. The eigenvalues were then used in the tapping mode system to predict the frequency responses against the tip-sample separations. It was found that the frequency drop steeply if the separation was less than certain distances. This instability of frequency is deduced from the jump of microcantilever or the jump of the carbon nanotube. Various lengths and binding angles of the carbon nanotube were considered, and the results indicated that the binding angle dominated the frequency responses and jumps.
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SAKURAI, Tsutomu, Harumichi KYOTOH, and Hitoshi NISHIMURA. "LOW FREQUENCY SOUND BY HYDRAULIC JUMP." PROCEEDINGS OF HYDRAULIC ENGINEERING 46 (2002): 607–12. http://dx.doi.org/10.2208/prohe.46.607.
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Gosain, K. L., D. K. Chaturvedi, Irina V. Belova, and Graeme E. Murch. "Tracer Diffusion by Six-Jump-Cycles in Nonstoichiometric B2 Intermetallic Compounds." Defect and Diffusion Forum 247-248 (December 2005): 9–20. http://dx.doi.org/10.4028/www.scientific.net/ddf.247-248.9.
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Tracer diffusion in non-stoichiometric B2 intermetallic compounds having antistructural disorder is investigated using the six-jump-cycle (6JC) as a fundamental diffusion unit. For non-stoichiometric compositions, the antistructural atoms are assumed to be isolated and located at one of the six [110]-type and [100]-type sites (as only these sites are involved in the 6JC or 2JC). The jump frequencies for the 6JC involving a perfectly ordered configuration are calculated in terms of a four-frequency-model, using the meanfirst- passage concept of Arita et al. The jump frequency of an antistructural atom at [110] or [100]-type sites is taken to be the harmonic mean of frequencies of two successive nearestneighbour jumps of the same kind of atoms. The expressions for the tracer diffusion coefficients are derived for both atomic components at deviations from stoichiometry, assuming that the 6JC mechanism is valid. The results are compared with Monte Carlo simulations based on single vacancy jumps and found to be in fair agreement for compositions close to stoichiometry.
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Pakdaman, K., M. Thieullen, and G. Wainrib. "Fluid limit theorems for stochastic hybrid systems with application to neuron models." Advances in Applied Probability 42, no. 3 (September 2010): 761–94. http://dx.doi.org/10.1239/aap/1282924062.
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In this paper we establish limit theorems for a class of stochastic hybrid systems (continuous deterministic dynamics coupled with jump Markov processes) in the fluid limit (small jumps at high frequency), thus extending known results for jump Markov processes. We prove a functional law of large numbers with exponential convergence speed, derive a diffusion approximation, and establish a functional central limit theorem. We apply these results to neuron models with stochastic ion channels, as the number of channels goes to infinity, estimating the convergence to the deterministic model. In terms of neural coding, we apply our central limit theorems to numerically estimate the impact of channel noise both on frequency and spike timing coding.
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Pakdaman, K., M. Thieullen, and G. Wainrib. "Fluid limit theorems for stochastic hybrid systems with application to neuron models." Advances in Applied Probability 42, no. 03 (September 2010): 761–94. http://dx.doi.org/10.1017/s0001867800050436.
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In this paper we establish limit theorems for a class of stochastic hybrid systems (continuous deterministic dynamics coupled with jump Markov processes) in the fluid limit (small jumps at high frequency), thus extending known results for jump Markov processes. We prove a functional law of large numbers with exponential convergence speed, derive a diffusion approximation, and establish a functional central limit theorem. We apply these results to neuron models with stochastic ion channels, as the number of channels goes to infinity, estimating the convergence to the deterministic model. In terms of neural coding, we apply our central limit theorems to numerically estimate the impact of channel noise both on frequency and spike timing coding.
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Xiao, Bo, Ya Liu, Yanrong Xue, and Xiaohui Li. "A Study on Autonomous Integrity Monitoring of Multiple Atomic Clocks." Measurement Science Review 22, no. 5 (August 5, 2022): 202–7. http://dx.doi.org/10.2478/msr-2022-0025.
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Abstract A stable and reliable time keeping system depends on the integrity monitoring of the atomic frequency standard. This paper reports a scheme for autonomous integrity monitoring of multiple atomic clocks, which combines the frequency standard comparison method and the frequency jump detection method. The frequency standard comparison method uses multi-channel synchronous acquisition technology and digital frequency measurement technology to realize the precise measurement of multiple atomic frequency standards. The frequency jump detection method uses adaptive filtering to predict the relative frequency difference and give an accurate and timely alarm for the abnormal of frequency jump. The results show that the noise floor frequency standard comparator is better than 6.5×10−15 s. For a relative frequency deviation of 2.0×10−6 Hz, the probability of anomaly detection is almost 100 %. The system has high frequency measurement resolution and fast alarm of frequency jump, which can meet the real-time requirements of a time keeping system for the integrity monitoring of multiple atomic clocks.
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D’Onofrio, Giuseppe, and Alessandro Lanteri. "Approximating the First Passage Time Density of Diffusion Processes with State-Dependent Jumps." Fractal and Fractional 7, no. 1 (December 28, 2022): 30. http://dx.doi.org/10.3390/fractalfract7010030.
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We study the problem of the first passage time through a constant boundary for a jump diffusion process whose infinitesimal generator is a nonlocal Jacobi operator. Due to the lack of analytical results, we address the problem using a discretization scheme for simulating the trajectories of jump diffusion processes with state-dependent jumps in both frequency and amplitude. We obtain numerical approximations on their first passage time probability density functions and results for the qualitative behavior of other statistics of this random variable. Finally, we provide two examples of application of the method for different choices of the distribution involved in the mechanism of generation of the jumps.
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Putera, Shidqi Hamdi Pratama, Hari Setijono, Oce Wiriawan, Nurhasan, Heryanto Nur Muhammad, Agus Hariyanto, Anindya Mar’atus Sholikhah, and Adi Pranoto. "Positive Effects of Plyometric Training on Increasing Speed, Strength and Limb Muscles Power in Adolescent Males." Physical Education Theory and Methodology 23, no. 1 (February 28, 2023): 42–48. http://dx.doi.org/10.17309/tmfv.2023.1.06.
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The study purpose was to prove the effectiveness of a plyometric jumping jack, countermovement jump, and tuck jump training in increasing speed, strength, and limb muscle power in adolescent males. Materials and methods. A total of 33 subjects from Santri Pondok Pesantren An-Nur 2 Al-Murtadlo Malang Regency, males, aged 18-22 years voluntarily participated in the study. The subjects were divided into 3 intervention groups, namely PJJ (n = 11, plyometric – jumping jacks), PCJ (n = 11, plyometric – countermovement jump), and PTJ (n= 11, plyometric – tuck jump). Plyometric jumping jacks, countermovement jump, and tuck jump training was conducted for 30 minutes/session, intensity 70-90% 1-RM, frequency 3x/week for 6 weeks. Measuring limb muscle power used the Jump Meter Digital (MD) Test, measuring limb muscle strength used the Back & Leg Dynamometer, and measuring speed used the 30 m running test. The data analysis technique used the Paired Sample T-Test with a significance level of 5%. Results. The results obtained were as follows: mean speed between pretest and posttest on PJJ (4.56±0.16 vs. 4.36±0.15 second, (p ≤ 0.001)), PCJ (4.61±0.15 vs. 4.54±0.14 second, (p ≤ 0.001)), PTJ (4.55±0.19 vs. 4.48±0.18 second, (p ≤ 0.001)), limb muscle strength between pretest and posttest in PJJ (111.45±18.94 vs. 139.27±20.23 kg, (p ≤ 0.001)), PCJ (117.73±21.03 vs. 129.55±19.24 kg, (p ≤ 0.001)), PTJ (115.46±17.66 vs. 125.91±18.62 kg, (p ≤ 0.001)), limb muscle power between pretest and posttest in PJJ (422.86±34.61 vs. 493.12±49.24 joule, (p ≤ 0.001)), PCJ (410.70±38.25 vs. 462.20±38.55 joule, (p ≤ 0.001)), PTJ (404.20±45.63 vs. 441.78±46.90 joule, (p ≤ 0.001)). Conclusions. Based on the results of the study, it was concluded that plyometric jumping jacks, countermovement jumps, and tuck jumps performed for 30 minutes/session, with an intensity of 70-90% 1-RM, frequency 3x/week for 6 weeks are effective in increasing limb muscle power, strength and speed.
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Park, Suk Jin, and Chae Shick Chung. "High Frequency Jump Analysis of Kospi200 Futures." Korean Data Analysis Society 22, no. 1 (February 28, 2020): 215–25. http://dx.doi.org/10.37727/jkdas.2020.22.1.215.
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Neves, Tiago de Assis, Rodrigo Ramirez-Campillo, and Ricardo Luis Fernandes Guerra. "Effect of different weekly frequencies of plyometric-jump and linear-sprint training on youth male futsal athlete’s physical fitness." Revista Brasileira de Fisiologia do exerc&iacute cio 21, no. 4 (February 2, 2023): 232–45. http://dx.doi.org/10.33233/rbfex.v21i4.5305.
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Introduction: This prospective cross-sectional intervention study aimed to compare the effect of different frequencies (equated for total repetitions) of plyometric-jump and linear-sprint training on U-18 (age, 17,0 ± 1,05) male futsal athlete’s physical fitness. Methods: Athletes (33) were randomly distributed into groups with one (1-TSW, n = 10), two (2-TSW, n = 11), and three (3-TSW, n = 12) training session per week (TSW), during 4 weeks of their regular futsal training routine. Plyometric-jump training involved bipedal and unipedal horizontal maximum-intensity jumps. Linear-sprint training involved maximal-intensity 10-msprints with 30 seconds of rest between sprints. Results: The three training groups completed an equal number of total jumps (n = 780) and sprints (n = 260). A two-way ANOVA with repeated measures on time revealed significant main effects of time for all physical fitness outcomes, i.e., squat jump and counter-movement jump height, power, relative power, standing long jump distance, 10-m and 20-m sprint time, and change of direction sprint time in the T-test (all p < 0.001; d = 0.36-0.69), without significant group × time interaction effects (p = 0.133-0.861; d = 0.01-0.13). Conclusion, Adding plyometric-jump and linear-sprint training to the standard training of youth male futsal athlete’s improves their physical fitness, with similar improvements regardless of the training frequency.
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Zacate, Matthew O., and Gary S. Collins. "Jump Frequency of Cd Tracer Atoms in β-Mn." Defect and Diffusion Forum 237-240 (April 2005): 396–401. http://dx.doi.org/10.4028/www.scientific.net/ddf.237-240.396.
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The jump frequency of Cd tracer atoms in pure and Al-doped b-Mn was determined from measurements of quadrupole relaxation using the method of perturbed angular correlation of gamma rays. The jump frequency of Cd in b-Mn containing about 4.5 at.% Al had an activation enthalpy of 0.67(3) eV. In pure b-Mn at 950 K, the jump frequency was a factor about 8 larger than the value of 9.2 MHz in the alloy. Information was also obtained about the sluggish kinetics of the a-Mn to b-Mn polymorphic transformation.
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GOVARDHAN, R., and C. H. K. WILLIAMSON. "Modes of vortex formation and frequency response of a freely vibrating cylinder." Journal of Fluid Mechanics 420 (October 10, 2000): 85–130. http://dx.doi.org/10.1017/s0022112000001233.
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In this paper, we study the transverse vortex-induced vibrations of an elastically mounted rigid cylinder in a fluid flow. We use simultaneous force, displacement and vorticity measurements (using DPIV) for the first time in free vibrations. There exist two distinct types of response in such systems, depending on whether one has a high or low combined mass–damping parameter (m*ζ). In the classical high-(m*ζ) case, an ‘initial’ and ‘lower’ amplitude branch are separated by a discontinuous mode transition, whereas in the case of low (m*ζ), a further higher-amplitude ‘upper’ branch of response appears, and there exist two mode transitions.To understand the existence of more than one mode transition for low (m*ζ), we employ two distinct formulations of the equation of motion, one of which uses the ‘total force’, while the other uses the ‘vortex force’, which is related only to the dynamics of vorticity. The first mode transition involves a jump in ‘vortex phase’ (between vortex force and displacement), ϕvortex, at which point the frequency of oscillation (f) passes through the natural frequency of the system in the fluid, f ∼ fNwater. This transition is associated with a jump between 2S [harr ] 2P vortex wake modes, and a corresponding switch in vortex shedding timing. Across the second mode transition, there is a jump in ‘total phase’, phis;total , at which point f ∼ fNvacuum. In this case, there is no jump in ϕvortex, since both branches are associated with the 2P mode, and there is therefore no switch in timing of shedding, contrary to previous assumptions. Interestingly, for the high-(m*ζ) case, the vibration frequency jumps across both fNwater and fNvacuum, corresponding to the simultaneous jumps in ϕvortex and ϕtotal. This causes a switch in the timing of shedding, coincident with the ‘total phase’ jump, in agreement with previous assumptions.For large mass ratios, m* = O(100), the vibration frequency for synchronization lies close to the natural frequency (f* = f/fN ≈ 1.0), but as mass is reduced to m* = O(1), f* can reach remarkably large values. We deduce an expression for the frequency of the lower-branch vibration, as follows:formula herewhich agrees very well with a wide set of experimental data. This frequency equation uncovers the existence of a critical mass ratio, where the frequency f* becomes large: m*crit = 0.54. When m* < m*crit, the lower branch can never be reached and it ceases to exist. The upper-branch large-amplitude vibrations persist for all velocities, no matter how high, and the frequency increases indefinitely with flow velocity. Experiments at m* < m*crit show that the upper-branch vibrations continue to the limits (in flow speed) of our facility.
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Liu, Mochi, Yu Chen, Qian Xu, Yuzhuo Wang, Yuan Gao, and Aimin Zhang. "Mirror Clock: A Strategy for Identifying Atomic Clock Frequency Jumps." Sensors 22, no. 22 (November 21, 2022): 8995. http://dx.doi.org/10.3390/s22228995.
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Atomic clock frequency jumps directly influence the accuracy and reliability of timekeeping systems. The necessary corrections are typically implemented by postprocessing mutual comparison data between multiple atomic clocks based on the overly strict assumption that these atomic clocks are independent of each other. This paper describes the concept of a mirror clock, which enables atomic clock frequency jumps to be identified in real time without any assumptions. By comparing whether the real measured data and a corresponding mirror clock prediction fall within a confidence interval determined by the uncertainty of past physical clock data, atomic clock frequency jumps can be effectively identified and corrected. The results of several experiments using three hydrogen masers verify that the precision and recall of simultaneous jump identification reach 96.41% and 73.49%, respectively.
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Lin, Shih-Kuei, Jin-Lung Peng, Wei-Hsiung Chao, and An-Chi Wu. "The extension from independence to dependence between jump frequency and jump size in Markov-modulated jump diffusion models." North American Journal of Economics and Finance 37 (July 2016): 217–35. http://dx.doi.org/10.1016/j.najef.2016.04.003.
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Andersen, Torben G., Nicola Fusari, Viktor Todorov, and Rasmus T. Varneskov. "INFERENCE FOR OPTION PANELS IN PURE-JUMP SETTINGS." Econometric Theory 35, no. 05 (October 19, 2018): 901–42. http://dx.doi.org/10.1017/s0266466618000373.
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We develop parametric inference procedures for large panels of noisy option data in a setting, where the underlying process is of pure-jump type, i.e., evolves only through a sequence of jumps. The panel consists of options written on the underlying asset with a (different) set of strikes and maturities available across the observation times. We consider an asymptotic setting in which the cross-sectional dimension of the panel increases to infinity, while the time span remains fixed. The information set is augmented with high-frequency data on the underlying asset. Given a parametric specification for the risk-neutral asset return dynamics, the option prices are nonlinear functions of a time-invariant parameter vector and a time-varying latent state vector (or factors). Furthermore, no-arbitrage restrictions impose a direct link between some of the quantities that may be identified from the return and option data. These include the so-called jump activity index as well as the time-varying jump intensity. We propose penalized least squares estimation in which we minimize the L2 distance between observed and model-implied options. In addition, we penalize for the deviation of the model-implied quantities from their model-free counterparts, obtained from the high-frequency returns. We derive the joint asymptotic distribution of the parameters, factor realizations and high-frequency measures, which is mixed Gaussian. The different components of the parameter and state vector exhibit different rates of convergence, depending on the relative (asymptotic) informativeness of the high-frequency return data and the option panel.
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Bucolo, Maide, Arturo Buscarino, Luigi Fortuna, and Mattia Frasca. "Multiple Hysteresis Jump Resonance in a Class of Forced Nonlinear Circuits and Systems." International Journal of Bifurcation and Chaos 30, no. 15 (December 9, 2020): 2050258. http://dx.doi.org/10.1142/s0218127420502582.
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In this paper, a new class of systems with nonclassical jump resonance behavior is presented. Although jump resonance has been widely studied in the literature, this contribution refers to systems presenting a multiple hysteresis jump resonance phenomenon, meaning that the frequency response of the system presents more hysteresis windows nested within the same range of frequency. The analytical conditions for observing this type of behavior are derived and a design strategy to obtain multiple hysteresis jump resonance in circuits and systems presented.
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Jiang, Xia, Matthew O. Zacate, and Gary S. Collins. "Jump Frequencies of Cd Tracer Atoms in L12 Lanthanide Gallides." Defect and Diffusion Forum 289-292 (April 2009): 725–32. http://dx.doi.org/10.4028/www.scientific.net/ddf.289-292.725.
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Jump frequencies of Cd tracer atoms were measured in three lanthanide gallides having the L12 structure: DyGa3, ErGa3 and LuGa3. 111In/Cd impurity probe atoms were observed to occupy the non-cubic Ga-sites through the nuclear quadrupole interaction using the method of perturbed angular correlation of gamma rays (PAC). Measurements at elevated temperatures exhibited nuclear relaxation (damping) of quadrupolar perturbation functions attributed to diffusional jumps of the probes among orientationally inequivalent Ga-sites. Accurate values of jump frequencies were determined from fits of the measured perturbation functions using a model of stochastically fluctuating electric-field gradients, as in previous work [e.g., Matthew O. Zacate, Aurélie Favrot and Gary S. Collins: Physical Review Letters Vol. 92 (2004) p. 225901]. Arrhenius plots of jump frequencies for the three systems exhibited jump-frequency activation enthalpies in the range 0.86-1.05 eV and prefactors of about 2 THz. The activation enthalpy for ErGa3, 0.86(2) eV is compared with those for ErAl3, 1.40(4) eV, and ErIn3, 1.34(5) eV.
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Sandhu, I. S., D. K. Chaturvedi, Irina V. Belova, and Graeme E. Murch. "Collective Correlation Factors in Random Non-Stoichiometric Inermetallic Compounds." Defect and Diffusion Forum 247-248 (December 2005): 1–8. http://dx.doi.org/10.4028/www.scientific.net/ddf.247-248.1.
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In this paper Manning random alloy model has been extended to the binary nonstoichiometric intermetallic compound of the B2 structure. Two sub-lattices, that are dynamically independent in six-jump cycle (6JC) mechanism, are coupled together by taking into consideration the vacancy motion as a sequence of nearest neighbour jumps in random directions. The linear response expressions for the phenomenological transport coefficients are evaluated making use of the kinetic equation approach. The expressions for collective correlation factors are derived in terms of the equilibrium partial atomic concentrations and jump frequencies. Results are compared with Monte Carlo simulation results using the four-frequency model.
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Coelho, Stanley S., Lucas Queiroz, and Danilo T. Alves. "Exact Solution of a Time-Dependent Quantum Harmonic Oscillator with Two Frequency Jumps via the Lewis–Riesenfeld Dynamical Invariant Method." Entropy 24, no. 12 (December 19, 2022): 1851. http://dx.doi.org/10.3390/e24121851.
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Harmonic oscillators with multiple abrupt jumps in their frequencies have been investigated by several authors during the last decades. We investigate the dynamics of a quantum harmonic oscillator with initial frequency ω0, which undergoes a sudden jump to a frequency ω1 and, after a certain time interval, suddenly returns to its initial frequency. Using the Lewis–Riesenfeld method of dynamical invariants, we present expressions for the mean energy value, the mean number of excitations, and the transition probabilities, considering the initial state different from the fundamental. We show that the mean energy of the oscillator, after the jumps, is equal or greater than the one before the jumps, even when ω1<ω0. We also show that, for particular values of the time interval between the jumps, the oscillator returns to the same initial state.
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Zhang, HuiLi. "Measurement of Economic Fluctuations Based on High-Frequency Financial Time Series." Security and Communication Networks 2022 (June 13, 2022): 1–18. http://dx.doi.org/10.1155/2022/9310697.
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In order to improve the analysis and forecasting effect of economic fluctuations, this paper combines the high-frequency financial sequence algorithm to conduct measured analysis of economic fluctuations. Under the continuous jump-diffusion price model, this paper considers the jump part and the continuous part in the process of asset pricing. Moreover, for the jump part, this paper uses the wavelet method to analyze the observation data, and obtains the estimator of the second-order jump covariation difference matrix and its convergence speed. For the continuous part, this paper adopts a two-scale realized volatility model under the continuous price model. In addition, this paper verifies the effect of the intelligent model proposed in this paper through simulation experiments. The simulation data shows that the economic fluctuation analysis system based on high-frequency financial time series proposed in this paper has good economic analysis and economic forecasting effects.
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Nazari, Maryam, Sahar Boozari, Giti Torkaman, and Mohammad Ali Sanjari. "Effect of Different Vibration Frequencies on Improving Sports Performance: A Review Article." Scientific Journal of Rehabilitation Medicine 11, no. 3 (July 23, 2022): 332–45. http://dx.doi.org/10.32598/sjrm.11.3.11.
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Background and Aims Whole body vibration (WBV) is one of the relatively new interventions that is widely used in physiotherapy and sports physiotherapy. It is becoming more common due to its positive effects on the neuromuscular system. The WBV device produces oscillations and its intensity is determined based on the parameters of frequency, amplitude, and duration of vibration. According to the previous studies, some parameters of this device results in increased muscle activity, strength, and power. Muscle strength and power are the two most important factors in musculoskeletal efficiency. As a result, sports performance variables such as jump height and running speed are affected by WBV. According to previous studies, if the vibration is applied with appropriate parameters, it can be effective in improving the performance of individuals in activities such as jumping and running. Furthermore, it has been shown that frequency parameter is more important than other vibration parameters since it has a greater effect on musculoskeletal performance. As a result, this study aims to review the studies on the effects of various WBV frequencies on functional variables in sports activities. Methods A search was conducted in PubMed, Scopus, and Google Scholar databases to find studies about the effect of WBV frequencies on jumping and running. Results According to previous studies, the frequency of 30-50 Hz resulted in an immediate increase in countermovement jump and squat jump heights. The frequencies of 18-35 Hz and 40 Hz, when used for a long time, also increased the heights of countermovement and squat jumps, respectively. In a few studies, the 26 and 20-Hz frequencies improved the heights of horizontal, countermovement, and squat jumps. Moreover, 30-Hz frequency increased running speed and step length and reduced the running duration in a certain distance. The frequency of 45-Hz immediately reduced the step length and increased the step rate during running on a treadmill. Conclusion The 30-Hz frequency is the most common WBV frequency with a positive effect on jumping and running abilities. In both acute and chronic conditions, this frequency may have a positive impact on the kinetic and kinematic variables of jumping and running. As a result, this frequency is suggested for improving an individual's neuromuscular performance in sports activities.
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Collins, Gary S., A. Favrot, L. Kang, D. Solodovnikov, and Matthew O. Zacate. "Diffusion in Intermetallic Compounds Studied Using Nuclear Quadrupole Relaxation." Defect and Diffusion Forum 237-240 (April 2005): 195–200. http://dx.doi.org/10.4028/www.scientific.net/ddf.237-240.195.
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The jump frequency of Cd tracer atoms was measured as a function of temperature in seven rare-earth tri-indide intermetallic compounds having the L12, or Cu3Au, structure. The frequency, proportional to the diffusivity, was detected by relaxation of nuclear quadrupole interaction at Cd nuclei caused by reorientation of the electric field gradient in each diffusive jump. Measurements were made using perturbed angular correlation of gamma rays, sensitive to jump frequencies in the range 1-1000 MHz. Results are as follows. (1) Jump frequencies measured in LaIn3 and CeIn3 were observed to be 10-100 times greater at the more In-rich boundary composition than the less In-rich boundary composition, even though the phases appear as line compounds in phase diagrams. (2) Arrhenius plots of the jump frequency were fitted to activation enthalpies that increase from 0.535 to 1.80 eV across the series of phases LaIn3, CeIn3, PrIn3, and NdIn3.
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Gosain, K. L., D. K. Chaturvedi, Irina V. Belova, and Graeme E. Murch. "Six-Jump-Cycle Mechanism for Collective Correlations in Nonstoichiometric Intermetallic Compounds." Defect and Diffusion Forum 251-252 (March 2006): 59–68. http://dx.doi.org/10.4028/www.scientific.net/ddf.251-252.59.
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The six-jump-cycle (6JC) mechanism is used to derive expressions for collective correlation factors in a nonstoichiometric binary intermetallic compound AB. The 6JC is used as a fundamental unit for the cycle involving a perfectly ordered configuration and a two-jumpcycle (2JC) as a fundamental unit for the cycle involving existing antistructural atoms. The jump frequency for the 6JC is calculated in terms of a four-frequency-model using the mean first passage concept of Arita et al., while the jump frequency for the 2JC is taken to be the harmonic mean of the individual jump frequencies. The expressions for phenomenological transport coefficients are obtained through the linear response approximation using the kinetic equation approach. The results for collective correlation factors are compared with Monte Carlo simulation and are found to be in reasonably good agreement when the ratio of jump frequencies of regular site and antistructural atoms is of the order of 10-1.
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Wogan, Tim. "Photons stay entangled despite huge jump in frequency." Physics World 35, no. 7 (August 1, 2022): 6i. http://dx.doi.org/10.1088/2058-7058/35/07/06.
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A new technique that keeps two photons entangled while greatly increasing the frequency of one of them has been demonstrated by researchers in Germany. The work could prove useful in quantum computation, imaging and quantum communications.
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Hong-Yi, Fan, and H. R. Zaidi. "Squeezing and frequency jump of a harmonic oscillator." Physical Review A 37, no. 8 (April 1, 1988): 2985–88. http://dx.doi.org/10.1103/physreva.37.2985.
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Castillo-Domínguez, Alejandro, Jerónimo C. García-Romero, Joaquín Páez-Moguer, Tomás Ponce-García, Miguel Medina-Alcántara, and José Ramón Alvero-Cruz. "Relationship between Running Spatiotemporal Kinematics and Muscle Performance in Well-Trained Youth Female Athletes. A Cross-Sectional Study." International Journal of Environmental Research and Public Health 18, no. 16 (August 23, 2021): 8869. http://dx.doi.org/10.3390/ijerph18168869.
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The purpose of this cross-sectional study was to analyse the relationship of neuromuscular performance and spatiotemporal parameters in 18 adolescent distance athletes (age, 15.5 ± 1.1 years). Using the OptoGait system, the power, rhythm, reactive strength index, jump flying time, and jump height of the squat jump, countermovement jump, and eight maximal hoppings test (HT8max) and the contact time (CT), flying time (FT), step frequency, stride angle, and step length of running at different speeds were measured. Maturity offset was determined based on anthropometric variables. Analysis of variance (ANOVA) of repeated measurements showed a reduction in CT (p < 0.000) and an increase in step frequency, step length, and stride angle (p < 0.001), as the velocity increased. The HT8max test showed significant correlations with very large effect sizes between neuromuscular performance variables (reactive strength index, power, jump flying time, jump height, and rhythm) and both step frequency and step length. Multiple linear regression found this relationship after adjusting spatiotemporal parameters with neuromuscular performance variables. Some variables of neuromuscular performance, mainly in reactive tests, were the predictors of spatiotemporal parameters (CT, FT, stride angle, and VO). Rhythm and jump flying time in the HT8max test and power in the countermovement jump test are parameters that can predict variables associated with running biomechanics, such as VO, CT, FT, and stride angle.
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Buscarino, Arturo, Riccardo Caponetto, Carlo Famoso, and Luigi Fortuna. "Jump Resonance in Fractional Order Circuits." International Journal of Bifurcation and Chaos 28, no. 01 (January 2018): 1850016. http://dx.doi.org/10.1142/s0218127418500165.
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The occurrence of an hysteretic loop in the frequency response of a driven nonlinear system is a phenomenon deeply investigated in nonlinear control theory. Such a phenomenon, which is linked to the multistable behavior of the system, is called jump resonance, since the magnitude of the frequency response is subjected to an abrupt jump up/down with respect to the increasing/decreasing of the frequency of the driving signal. In this paper, we aim at investigating fractional order nonlinear systems showing jump resonance, that is systems in which the order of the derivative is noninteger and their frequency response has a magnitude that is a multivalued function in a given range of frequencies. Furthermore, a strategy for designing fractional order systems showing jump resonance is presented along with the procedure to design and implement an analog circuit based on the approximation of the fractional order derivative. An extensive numerical analysis allows one to assess that the phenomenon is robust to the difference in the derivative order, enlightening the first example of a system with order lower than two which is able to demonstrate a jump resonance behavior.
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Lu, Ze-Qi, Guang-Shen Hu, Hu Ding, and Li-Qun Chen. "Jump-based estimation for nonlinear stiffness and damping parameters." Journal of Vibration and Control 25, no. 2 (May 19, 2018): 325–35. http://dx.doi.org/10.1177/1077546318777414.
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To overcome the limitation that only stiffness nonlinearity can be estimated via jump frequencies, this work introduces jump amplitudes as a supplement condition in the estimation of both stiffness and damping nonlinearities. An estimation method is proposed for a single-degree-of-freedom system containing both stiffness and damping nonlinearities. The idea may be applied to other nonlinear systems. The method is based on the measurements of both jump frequencies and jump amplitudes of the system subject to swept-sine excitations respectively in frequency and in amplitude. The experimental data yield frequency response curves at a fixed excitation amplitude and amplitude response curves at a fixed frequency. Based on the measured jump frequencies and jump amplitudes of the displacements, the system parameters can be determined by the method of harmonic balance. A numerical example is presented to demonstrate the application of the proposed approach and to check approximate explicit analytical expressions of the parameter estimation. To validate the effectiveness of the proposed approach, an experiment is performed on a vibration isolator with strongly nonlinear stiffness and damping. The estimation results show that the proposed method can estimate the stiffness and the damping parameters of the system with strong nonlinearities. Hence exploiting the knowledge about nonlinear jump phenomena is a promising approach to parameter estimations.
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Sha, Zhanxin, Zhaoxian Zhou, and Boyi Dai. "Analyses of Countermovement Jump Performance in Time and Frequency Domains." Journal of Human Kinetics 78, no. 1 (March 1, 2021): 41–48. http://dx.doi.org/10.2478/hukin-2021-0028.
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Abstract This study aimed to analyze counter-movement jump (CMJ) performance in time and frequency domains. Fortyfour Division I American football players participated in the study. Kinetic variables were collected from both dominant and non-dominant legs using two force plates. Normalized peak power, normalized net impulse, and normalized peak force significantly correlated with jump height (r = .960, r = .998, r = .725, respectively with p < .05). The mean frequency component was significantly correlated with CMJ performance (r = .355 with p < .05). The reliability of the frequency variables was higher than the time domain variables. Frequency domain variables showed weaker correlations with jump height compared with time domain variables. Frequency domain analysis provides frequency components, which represent the rate of energy transmission from the eccentric phase to the end of the push-off phase. Frequency component information may provide additional information for the analyses of CMJ performance for athletes.
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Wan, Jian, Dianfei Zhang, Wei Xu, and Qiang Guo. "Parameter Estimation of Multi Frequency Hopping Signals Based on Space-Time-Frequency Distribution." Symmetry 11, no. 5 (May 8, 2019): 648. http://dx.doi.org/10.3390/sym11050648.
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Frequency hopping spread spectrum (FHSS) communication is widely used in military and civil communication, and the parameter estimation of frequency hopping (HF) signals is of great significance. In order to estimate the parameters of multiple frequency hopping signals effectively, a blind parameter estimation algorithm based on space-time frequency analysis (STFA) and matrix joint diagonalization (JDM) is proposed. Firstly, the time domain signal received by the linear array is converted to the space-time frequency domain through the space-time frequency transformation, and the space-time frequency distribution (STFD) of the signal is obtained. Then the time-frequency point is extracted from the space-time frequency distribution map, the extraction of the hop is completed by the method of finding an “island”, and the space-time frequency matrix of each hop is constructed, and then the preliminary estimation of each jump frequency, jump time and jump period is completed. Finally, the space-time-frequency matrix of the same hop received by different array elements is jointly diagonalized by the matrix joint diagonalization algorithm, and the diagonalization matrix is obtained. On the basis of the diagonalization matrix, the root-MUSIC algorithm is used to complete the direction of arrival (DOA) estimation of the frequency hopping signal and the separation of the frequency hopping radio. The simulation results show that the proposed algorithm is effective in parameter estimation of multi-hopping signals. It can estimate the parameters of −4 dB signal-to-noise ratio (SNR). The accuracy rate of parameter (hop period, DOA, hop start time, hop end time, frequency hopping frequency set) estimation reaches 73.26%, and the sparse linear regression (SLR) algorithm reaches 70.15%. When the signal-to-noise ratio reaches 5 dB, the accuracy of estimation can reach 94.74%, and the SLR reach 85.64%. It has a good effect on parameter estimation of multi-hopping signals.
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Collins, Gary S., Qiao Ming Wang, and John P. Bevington. "Impurity Diffusion in Highly-Ordered Intermetallic Compounds Studied by Nuclear Quadrupole Interactions." Diffusion Foundations 2 (September 2014): 95–105. http://dx.doi.org/10.4028/www.scientific.net/df.2.95.
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Diffusion of impurity atoms depends on the sublattices occupied, active diffusion mechanisms, and jump frequencies to neighboring sites. The method of perturbed angular correlation of gamma rays (PAC) has been applied over the past decade to study impurity diffusion through measurement of nuclear quadrupole interactions (NQI) at nuclei of 111In/Cd probe atoms. Extensive measurements have been made on highly-ordered compounds having the L12 crystal structure, including In3R, Sn3R, Ga3R, Al3R and Pd3R phases (R= rare-earth element). Measurements in thermal equilibrium at high temperature served to determine lattice locations of 111In parent probe-atoms, through characteristic NQIs, and to measure diffusional jump-frequencies of 111Cd daughter probe-atoms, through relaxation of the NQI. This paper summarizes results of the jump-frequency measurements and relates them to the conventional diffusivity that can be determined, for example, from penetration profiles of tracer species. In spite of chemical similarities of the series of rare-earth phases studied, remarkably large variations in jump frequencies have been observed especially along series of In3R and Pd3R phases. Most phases appear as “line compounds” in binary phase diagrams, but large differences in site-preferences and jump-frequencies were observed for samples prepared to have the opposing limiting phase boundary compositions. Comparisons of jump-frequencies measured at opposing boundary compositions can give insight into the predominant microscopic diffusional mechanisms of the impurity. A change in diffusion mechanism was proposed in 2009 to explain jump-frequency systematics for In3R phases. An alternative explanation is proposed in the present paper based on site-preferences of 111Cd daughter probes newly observed along the parallel Pd3R series. The diffusivity can be expressed as the product of a jump-frequency such as measured in these studies and a correlation factor for diffusion that depends on the diffusion mechanism. The correlation factor can be modeled for the L12 structure and diffusion sublattice of interest using a five-frequency model originally proposed for metals. Although the correlation factor is an essential parameter for the diffusion of impurities, it has never been measured. It is suggested that values of the correlation factor can be determined feasibly by combining results of jump-frequency measurements such as the present ones with diffusivity measurements made for the same host-impurity systems.
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Bruening, Dustin A., and James G. Richards. "The Effects of Articulated Figure Skates on Jump Landing Forces." Journal of Applied Biomechanics 22, no. 4 (November 2006): 285–95. http://dx.doi.org/10.1123/jab.22.4.285.
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Lower extremity injuries in figure skating have long been linked to skating boot stiffness, and recent increases in jump practice time may be influencing the frequency and seriousness of these injuries. It is hypothesized that stiff boots compromise skaters' abilities to attenuate jump landing forces. Decreasing boot stiffness by adding an articulation at the ankle may reduce the rate and magnitude of landing forces. Prototype articulated figure skating boots were tested in this study to determine their effectiveness in enabling skaters to land with lower peak impact forces. Nine competitive figure skaters, who trained in standard boots and subsequently in articulated boots, performed off-ice jump simulations and on-ice axels, double toe loops, and double axels. Analysis of the off-ice simulations showed decreases in peak heel force and loading rate with use of the articulated boot, although the exact kinematic mechanisms responsible for these decreases are still unclear. Analysis of the on-ice jumps revealed few kinematic differences between boot types, implying that the skaters did not use the articulation. Greater adaptation and training time is likely needed for the results seen off-ice to transfer to difficult on-ice jumps.
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Shen, Ze-Min, Xiao-Long Zhou, Dong-Yu Huang, Yu-Hao Pan, Li Li, Jian Wang, Chuan-Feng Li, and Guang-Can Guo. "Continuously and widely tunable frequency-stabilized laser based on an optical frequency comb." Review of Scientific Instruments 94, no. 2 (February 1, 2023): 023001. http://dx.doi.org/10.1063/5.0120119.
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Continuously and widely tunable lasers, actively stabilized on a frequency reference, are broadly employed in atomic, molecular, and optical (AMO) physics. The frequency-stabilized optical frequency comb (OFC) provides a novel optical frequency reference, with a broadband spectrum that meets the requirement of laser frequency stabilization. Therefore, we demonstrate a frequency-stabilized and precisely tunable laser system based on it. In this scheme, the laser frequency locked to the OFC is driven to jump over the ambiguity zones, which blocks the wide tuning of the locked laser, and tuned until the mode hopping happens with the always-activated feedback loop. Meanwhile, we compensate the gap of the frequency jump with a synchronized acoustic optical modulator to ensure the continuity. This scheme is applied to an external cavity diode laser (ECDL), and we achieve tuning at a rate of about 7 GHz/s, with some readily available commercial electronics. Furthermore, we tune the frequency-stabilized laser only with the feedback of diode current, and its average tuning speed can exceed 100 GHz/s. Due to the resource-efficient configuration and the simplicity of completion, this scheme can be referenced and can find wide applications in AMO experiments.
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Maćkała, Krzysztof, Marek Fostiak, and Kacper Kowalski. "Selected Determinants of Acceleration in the 100m Sprint." Journal of Human Kinetics 45, no. 1 (March 1, 2015): 135–48. http://dx.doi.org/10.1515/hukin-2015-0014.
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Abstract The goal of this study was to examine the relationship between kinematics, motor abilities, anthropometric characteristics, and the initial (10 m) and secondary (30 m) acceleration phases of the 100 m sprint among athletes of different sprinting performances. Eleven competitive male sprinters (10.96 s ± 0.36 for 100 with 10.50 s fastest time) and 11 active students (12.20 s ± 0.39 for 100 m with 11.80 s fastest time) volunteered to participate in this study. Sprinting performance (10 m, 30 m, and 100 m from the block start), strength (back squat, back extension), and jumping ability (standing long jump, standing five-jumps, and standing ten-jumps) were tested. An independent t-test for establishing differences between two groups of athletes was used. The Spearman ranking correlation coefficient was computed to verify the association between variables. Additionally, the Ward method of hierarchical cluster analysis was applied. The recorded times of the 10 and 30 m indicated that the strongest correlations were found between a 1- repetition maximum back squat, a standing long jump, standing five jumps, standing ten jumps (r = 0.66, r = 0.72, r = 0.66, and r = 0.72), and speed in the 10 m sprint in competitive athletes. A strong correlation was also found between a 1-repetition maximum back squat and a standing long jump, standing five jumps, and standing ten jumps (r = 0.88, r = 0.87 and r = 0.85), but again only for sprinters. The most important factor for differences in maximum speed development during both the initial and secondary acceleration phase among the two sub-groups was the stride frequency (p<0.01).
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Gyulai, Elisabetta. "The “Jump” Effect." Perceptual and Motor Skills 83, no. 3 (December 1996): 707–14. http://dx.doi.org/10.2466/pms.1996.83.3.707.
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The jump effect occurs when an object, for example, a small square, moves on a homogeneous background at a constant velocity along its path except for a short section wherein the velocity suddenly changes to a higher value. In correspondence with this increase, observers may report that the object appears to jump. The experiments reported here explored the velocity conditions which determine the occurrence of this perceptual jump. A difference of at least 15 cm/sec. between the two velocities of the object was necessary for the effect to occur with probability 0.5. With slightly lower frequency, the effect also occurred when the object increased its velocity to a higher constant value in a short part of its path and then stopped. For the phenomenal jump to occur in all the different conditions used, there had to be an optimal length of the path in which the object increased its velocity. Finally, both velocities, before and after this increase, influenced the jump, although each with different weight.