Exponential Taper Research Articles

Biomass allometric models for Larix rupprechtii based on Kosak's taper curve equations and nonlinear seemingly unrelated regression.

The diameter at breast height (DBH) is the most important independent variable in biomass allometry models based on metabolic scaling theory (MST) or geometric theory. However, the fixed position DBH can be misleading in its use of universal scaling laws and lead to some deviation for the biomass model. Therefore, it is still an urgent scientific problem to build a high-precision biomass model system. A dataset of 114 trees was destructively sampled to obtain dry biomass components, including stems, branches, and foliage, and taper measurements to explore the applicability of biomass components to allometric scaling laws and develop a new system of additive models with the diameter in relative height (DRH) for each component of a Larch (Larix principis-rupprechtii Mayr) plantation in northern China. The variable exponential taper equations were modelled using nonlinear regression. In addition, applying nonlinear regression and nonlinear seemingly unrelated regression (NSUR) enabled the development of biomass allometric models and the system of additive models with DRH for each component. The results showed that the Kozak's (II) 2004 variable exponential taper equation could accurately describe the stem shape and diameter in any height of stem. When the diameters in relative height were D0.2, D0.5, and D0.5 for branches, stems, and foliage, respectively, the allometric exponent of the stems and branches was the closest to the scaling relations predicted by the MST, and the allometric exponent of foliage was the most closely related to the scaling relations predicted by geometry theory. Compared with the nonlinear regression, the parameters of biomass components estimated by NSUR were lower, and it was close to the theoretical value and the most precise at forecasting. In the study of biomass process modelling, utilizing the DRH by a variable exponential taper equation can confirm the general biological significance more than the DBH of a fixed position.

On the Estimation of Resonance Widths of Field Line Resonances Using Ground Magnetometer Data

This paper presents a comparison of three methods to estimate the latitudinal resonance width of field line resonant, ultra-low frequency waves detected at the ground. These are a spatial domain, full-width half-maximum method and frequency domain amplitude-phase and amplitude-division methods. These methods were used to estimate the resonance width of several field line resonant intervals occurring on 26 November 2001, 1 October 2012, and 19 June 2015. The 19 June 2015 interval used data from one low, two mid, and one high latitudes. It was found that the resonance width estimates were different for each method and with how the data were processed. The most suitable methods and data processing were determined from a damped driven harmonic oscillator model. The amplitude-division methods yielded the most accurate results when the ground magnetic field data were processed with a boxcar window function or a frequency domain, exponential smoothing taper. The amplitude-phase method tended to underestimate the resonance width. The full-width half-maximum method gave accurate results for a high spatial resolution linear piece-wise curve fitted to the spectral amplitude with latitude profile. An accurate estimate of the latitudinal resonance width requires a correct choice of data processing, estimate method, resonance profile with latitude, and resonance model.

Impact of tapering and proactive recovery on young elite rugby union players’ repeated high intensity effort ability

To assess the effects of a taper combined with proactive recovery on the repeated high intensity effort (RHIE) of elite rugby union players, and the possible interaction of pre-taper fatigue and sleep. Eighteen players performed a 3-week intensive training block followed by a 7-day exponential taper combined with a multicomponent recovery strategy. Following the intervention, players were divided into 3 groups (Normal Training: NT, Acute Fatigue: AF or Functional Overreaching: F-OR) based on their readiness to perform prior to the taper. Total sprint time [TST], percentage decrement [%D] and the number of sprints ≥90% of the best [N90] were analyzed to assess performance during a RHIE test. Subjective sleep quality was assessed through the Pittsburg Sleep Quality Index (PSQI) and the Epworth Sleepiness Scale (ESS). No improvement in TST was reported in either NT or F-OR after the taper, whereas AF tended to improve (-1.58 ± 1.95%; p > 0.05; g = -0.20). F-OR players reported baseline PSQI and ESS indicative of sleep disturbance (6.2 ± 2.2 and 10.6 ± 5.4, respectively). AF displayed a small impairment in PSQI during intensive training (11.5 ± 80.6%; p > 0.05; g = 0.20), which was reversed following the taper (-34.6 ± 62.1%; p > 0.05; g = -0.73). Pre-taper fatigue precluded the expected performance benefits of the combined taper and recovery intervention, likely associated with a lack of strictly controlled intensive training block. Poor sleep quality before the intensive training period appeared to predispose the players to developing functional overreaching.

Skeletal Muscle Adaptations and Performance Outcomes Following a Step and Exponential Taper in Strength Athletes.

Before major athletic events, a taper is often prescribed to facilitate recovery and enhance performance. However, it is unknown which taper model is most effective for peaking maximal strength and positively augmenting skeletal muscle. Thus, the purpose of this study was to compare performance outcomes and skeletal muscle adaptations following a step vs. an exponential taper in strength athletes. Sixteen powerlifters (24.0 ± 4.0 years, 174.4 ± 8.2 cm, 89.8 ± 21.4 kg) participated in a 6-week training program aimed at peaking maximal strength on back squat [initial 1-repetition-maximum (1RM): 174.7 ± 33.4 kg], bench press (118.5 ± 29.9 kg), and deadlift (189.9 ± 41.2 kg). Powerlifters were matched based on relative maximal strength, and randomly assigned to either (a) 1-week overreach and 1-week step taper or (b) 1-week overreach and 3-week exponential taper. Athletes were tested pre- and post-training on measures of body composition, jumping performance, isometric squat, and 1RM. Whole muscle size was assessed at the proximal, middle, and distal vastus lateralis using ultrasonography and microbiopsies at the middle vastus lateralis site. Muscle samples (n = 15) were analyzed for fiber size, fiber type [myosin-heavy chain (MHC)-I, -IIA, -IIX, hybrid-I/IIA] using whole muscle immunohistochemistry and single fiber dot blots, gene expression, and microRNA abundance. There were significant main time effects for 1RM squat (p < 0.001), bench press (p < 0.001), and deadlift, (p = 0.024), powerlifting total (p < 0.001), Wilks Score (p < 0.001), squat jump peak-power scaled to body mass (p = 0.001), body mass (p = 0.005), fat mass (p = 0.002), and fat mass index (p = 0.002). There were significant main time effects for medial whole muscle cross-sectional area (mCSA) (p = 0.006) and averaged sites (p < 0.001). There was also a significant interaction for MHC-IIA fiber cross-sectional area (fCSA) (p = 0.014) with post hoc comparisons revealing increases following the step-taper only (p = 0.002). There were significant main time effects for single-fiber MHC-I% (p = 0.015) and MHC-IIA% (p = 0.033), as well as for MyoD (p = 0.002), MyoG (p = 0.037), and miR-499a (p = 0.033). Overall, increases in whole mCSA, fCSA, MHC-IIA fCSA, and MHC transitions appeared to favor the step taper group. An overreach followed by a step taper appears to produce a myocellular environment that enhances skeletal muscle adaptations, whereas an exponential taper may favor neuromuscular performance.

Tapering and Repeated High-Intensity Effort Ability in Young Elite Rugby Union Players: Influence of Pretaper Fatigue Level.

To assess the effects of a short-term taper on the ability to perform repeated high-intensity efforts, depending on players' fatigue level following an intensive training block. After a 3-day off-season camp, 13 players followed the same 3-week preseason training block followed by a 7-day exponential taper. Performance was assessed by a repeated high-intensity effort test before and after the taper. Total sprint time, percentage of decrement, and the number of sprints equal to or higher than 90% of the best sprint were retained for analysis. Players were a posteriori classified in normal training or acute fatigue groups based on their readiness to perform prior to the taper, assessed through the magnitude of difference in psychological (Profile of Mood State Questionnaire), cardiovascular (submaximal constant-duration cycling), and neuromuscular (countermovement jump) tests between the preintensive and postintensive training blocks. Training load declined by 55% (9%) during the taper (P = .001, g = -2.54). The overall group showed a small improvement in total sprint time (-3.40% [3.90%], P = .04, g = -0.39) following the taper. Relative changes tended to be higher in the acute fatigue compared with the normal training group (-5.07% [4.52%] vs -1.45% [1.88%], respectively; P = .08; d = 1.01). No taper-induced improvement was observed in percentage of decrement or number of sprints equal to or higher than 90% of the best sprint. A 7-day taper consisting of 55% training load reduction improved repeated high-intensity effort performance in young elite rugby union players. Pretaper level of fatigue seems to be a key determinant in the taper supercompensation process, as acutely fatigued players at the end of the intensive training block tended to benefit more from the taper.

Changes of Event Size Distribution During Episodes of Shallow Tectonic Tremor, Nankai Trough

AbstractSlow earthquakes follow a power‐law size distribution with an exponential taper for the largest events. We investigated changes in the size distribution of shallow tectonic tremor events during two prolonged tremor episodes (&gt;1 month) along the Nankai trough and found that the slope of the size distributions increased while the cut‐off magnitudes decreased late during each episode, as tremor activity waned. Interpreting these changes with the two‐dimensional probabilistic cell automaton model of slow earthquakes, we found that a decrease in event ignition probability or an increase in energy dissipation during slip can qualitatively explain the observed changes. These changes imply that a decrease in accumulated stress or pore‐fluid pressure on the fault interface occurred during each tremor episode. Because the tremor source migrates during an episode, the changes in the size distribution parameters can be attributed to spatial variations or temporal changes in the source characteristics.

Microstrip to Double Ridge Empty Substrate Integrated Waveguide Transitions Based on Exponential and Superelliptical Dielectric Taper

Microstrip to Double Ridge Empty Substrate Integrated Waveguide Transitions Based on Exponential and Superelliptical Dielectric Taper

Stress‐Dependent Magnitudes of Induced Earthquakes in the Groningen Gas Field

AbstractGeological faults may produce earthquakes under induced stresses associated with hydrocarbon extraction, geothermal extraction, or CO2 storage. The associated risks depend on the frequency and magnitude of these earthquakes. Within seismic risk analysis, the exceedance probability of seismic moments, , is treated as a pure power law distribution, , where the power law exponent, β, may vary in time or space or with stress. Insights from statistical mechanics theories of brittle failure, statistical seismology, and acoustic emissions experiments all indicate this pure power law may contain an exponential taper, , where the taper strength, ζ, decreases with increasing stress. The role of this taper is to significantly reduce the probability of earthquakes larger than ζ −1 relative to the pure power law. We review the existing theoretical and observational evidence for a stress‐dependent exponential taper to motivate a range of magnitude models suitable for induced seismicity risk analysis. These include stress‐invariant models with and without a taper, stress‐dependent β models without a taper, and stress‐dependent ζ models. For each of these models, we evaluated their forecast performance within the Groningen gas field in the Netherlands using a combination of Bayesian inference, and simulations. Our results show that the stress‐dependent ζ model with constant β likely offers (75–85%) higher performance forecasts than the stress‐dependent β models with . This model also lowers the magnitudes with a 10% and 1% chance of exceedance over the next 5 years of gas production from 4.3 to 3.7 and from 5.5 to 4.3, respectively.

Efficient, wide-band coupled structural-acoustic computations combining time and frequency domain finite elements/equivalent sources

Time and frequency domain computations are complementary, and here, the overall goal is to combine them to generate wide-band solutions of coupled structural-acoustic problems. Modal frequency response computations are efficient for low frequencies but become inefficient as the number of basis functions required to represent the response grows large. Modal formulations are required for large problems because the coupled equation system becomes densely populated when acoustic pressure forces are included. In contrast, the equation system remains sparsely populated in time domain formulations when the time step size is chosen appropriately, allowing large problems to be solved efficiently in terms of nodal degrees-of-freedom. However, the analysis times depend linearly on the number of time steps and a large number are generally required to represent the ringing response of low frequency modes. Here, the number of time steps is limited by applying an exponential taper to the time domain solution and truncating the computations. This reduces leakage effects, but does not affect components of response that have damped out before it is applied. Examples are given to illustrate the computations and the tradeoff between number of basis functions in the modal frequency response computations and number of time steps in the transient analyses.Time and frequency domain computations are complementary, and here, the overall goal is to combine them to generate wide-band solutions of coupled structural-acoustic problems. Modal frequency response computations are efficient for low frequencies but become inefficient as the number of basis functions required to represent the response grows large. Modal formulations are required for large problems because the coupled equation system becomes densely populated when acoustic pressure forces are included. In contrast, the equation system remains sparsely populated in time domain formulations when the time step size is chosen appropriately, allowing large problems to be solved efficiently in terms of nodal degrees-of-freedom. However, the analysis times depend linearly on the number of time steps and a large number are generally required to represent the ringing response of low frequency modes. Here, the number of time steps is limited by applying an exponential taper to the time domain solution and truncat...

Event Size Distribution of Shallow Tectonic Tremor in the Nankai Trough

AbstractSlow earthquake size distributions have been found to follow either a power law or an exponential law, depending on the data set. We investigated the size distribution of shallow tectonic tremor events along the Nankai trough, southwestern Japan, observed in 2009, 2015, 2016, and 2018 and estimated the seismic energy radiated during the events as a measure of event size. The obtained size distributions mostly followed a power law with a b value of about 1, but an exponential law also fits well the data of the largest events; this result indicates that the size distribution follows the Gutenberg‐Richter law with an exponential taper. If only the largest events were observed, an exponential size distribution would be obtained. This exponential taper could be attributed to a source fault limitation. Because the maximum event size differed among activity periods, the source fault size varied among them, although the source areas largely overlap.

Multioctave Bandwidth of Parallel-Feeding Network Based on Impedance Transformer Concept

A generalized scheme to design a parallel-feeding network with a bandwidth of several octaves for uniform distribution arrays is proposed. Considering the entire network as a continuous impedance-transition device between the feed and all element ports, and therefore applying the design methods of the impedance transformer on the device, a broad matching bandwidth can be achieved without the traditional quarter-wavelength T-junctions concept. Three feeding networks based on the binomial and Chebyshev polynomial and exponential taper transformers for a $4 \times 4$ patch array are designed for demonstration, verification, and comparison of the proposed concept. An experimental sample of the taper network is fabricated and tested, and a fractional bandwidth better than 3:1 can be achieved. This method is not limited to the specific form of transmission lines and can perform even better for grander scale arrays.

Ultrahigh sensitivity with different taper geometries of thin-core fiber modal interferometer for refractive index sensing

A highly sensitive refractive index sensor based on a fiber in-line Mach–Zehnder interferometer sensor based on single-mode–tapered thin-core–single-mode fiber is proposed. We developed a theoretical model using wide-angle beam propagation method in cylindrical coordinates to simulate light propagation performance of such fiber devices. Tapered structures using different taper geometries (linear, exponential, and parabolic taper) with waist diameters as low as 30 μm are presented. The proposed sensor has an ultrahigh sensitivity of 996.4 nm/refractive index unit in glycerin solution with different concentrations in water using the linear taper geometry. The designed structure presents the merits of high sensitivity, which is 6 times higher than that of the thin-core fiber modal interferometer and makes it an excellent candidate for biochemical sensing applications.

&lt;inline-formula&gt; &lt;tex-math notation="LaTeX"&gt;$W$ &lt;/tex-math&gt; &lt;/inline-formula&gt;-Band Micromachined Antipodal Vivaldi Antenna Using SIW and CPW Structures

A novel W-band (75–110 GHz) surface micromachined Vivaldi antenna fed with a new combination of coplanar waveguide and substrate-integrated waveguide is proposed. The design procedure of the feeding structure and the effects of the antenna’s key structural features on its return loss and gain are studied in detail. The selected exponential taper with optimized feeding parameters results in a significantly higher gain (gain > 10 dBi) compared to similar tapered slot antennas reported in the literature over the entire bandwidth of operation. The antenna is fabricated using microfabrication processes, and high correlations between simulation and measurement results confirm its low-loss performance and symmetric and stable radiation pattern over the entire frequency range of 75–110 GHz.

Systems model and individual simulations of training strategies in elite short-track speed skaters

ABSTRACTThis study aimed to evaluate the effect of simulated training strategies on performance potential in elite short-track speed skaters. Training load and field-based criterion performances from fifteen athletes (10 males, 5 females) were collected over a 3-month training period and the relationship between training loads and performance was computed with a variable dose-response model using a genetic algorithm. Individual simulations of tapers preceded or not preceded by an overload training (OT) were assessed. We obtained a significant correlation between actual and modelled performances (R2 = 0.76 ± 0.07). Regarding model parameters, no significant difference was found between males and females but the time to recover performance tended to be lower in females. Simulations in which the taper parameters were free highlighted that an exponential or a step taper were the most effective for increasing performance compared to a linear taper (p < 0.05). Optimal exponential taper duration after OT was 10.7 ± 2.4d and the optimal load reduction was 75.9 ± 3.7%. OT intensity had the greatest influence on the predicted performance, followed by OT duration, taper decay, and to a lesser extent load reduction during taper and taper duration. Thus, a variable dose-response systems model allows the evaluation of different taper strategies and their potential effect on performance changes.

Direct mapping of the temperature and velocity gradients in discs

Accurate measurements of the physical structure of protoplanetary discs are critical inputs for planet formation models. These constraints are traditionally established via complex modelling of continuum and line observations. Instead, we present an empirical framework to locate the CO isotopologue emitting surfaces from high spectral and spatial resolution ALMA observations. We apply this framework to the disc surrounding IM Lupi, where we report the first direct, i.e. model independent, measurements of the radial and vertical gradients of temperature and velocity in a protoplanetary disc. The measured disc structure is consistent with an irradiated self-similar disc structure, where the temperature increases and the velocity decreases towards the disc surface. We also directly map the vertical CO snow line, which is located at about one gas scale height at radii between 150 and 300 au, with a CO freeze-out temperature of 21 ± 2 K. In the outer disc (&gt;300 au), where the gas surface density transitions from a power law to an exponential taper, the velocity rotation field becomes significantly sub-Keplerian, in agreement with the expected steeper pressure gradient. The sub-Keplerian velocities should result in a very efficient inward migration of large dust grains, explaining the lack of millimetre continuum emission outside of 300 au. The sub-Keplerian motions may also be the signature of the base of an externally irradiated photo-evaporative wind. In the same outer region, the measured CO temperature above the snow line decreases to ≈15 K because of the reduced gas density, which can result in a lower CO freeze-out temperature, photo-desorption, or deviations from local thermodynamic equilibrium.

UWB Single Port Log Periodic Toothed Terahertz Antenna Design Based on Graphene Artificial Magnetic Conductor

In this work, a single port exponential tapered toothed log periodic antenna based on graphene artificial magnetic conductor (AMC) is suggested for ultra-wideband (1–10) THz operation. The resonance frequency of the proposed antenna can be tuned by changing the connected DC voltage which leads to variation in the chemical potential of the graphene.The radiating toothed log periodic antenna consists of gold patch placed on 25x25 graphene patches which act as an AMC surface unit. Exponential taper is used to satisfy impedance matching between the antenna and the feeder over the frequency range. The simulation results reveal that 90% of frequency range satisfies when the chemical potential is1eV.

Analysis and Design of an Exponential Taper Slotted Antenna with Improved Gain by using Leaf Shaped Slots

This paper proposes a low profile, novel Taper Slotted Antenna (TSA) with manifold slots of Leaf shaped slots in order to improve the gain of a traditional Vivaldi Antenna without altering the dimensions of the antenna. Leaf shaped slots are cut on the antenna to enhance the existing radiation so that gain gets improved. The antenna is printed on a FR4 epoxy substrate which is economical. This proposed antenna provides an impedance bandwidth of 5:1 i.e over the range of 3.6 GHz to 18 GHz and a pattern bandwidth of 3.4 GHz to 18 GHz. The proposed antenna covers UWB, X band and Ku band which can be applicable for Radar and Satellite applications.

Effect of the electrostimulation during the tapering period compared to the exponential taper on anaerobic performances and rating of perceived exertion

Summary Objective The purpose of the present study was to assess the effect of exponential taper and electrostimulation training during two weeks of tapering on anaerobic performances after resistance training program. Methods Twenty-eight healthy male (age: 17.7 ± 0.8 years; height: 187.1 ± 3.9 cm; weight: 76.7 ± 6.6 kg, and body mass index: 21.9 ± 1.6 kg⋅m−2) were divided into three groups: control group, exponential taper group and electrostimulation taper group. During resistance period, all groups followed the same training program during 5 weeks (3 sets × 10 repetitions with 2 min of rest; intensity = 10 repetition maximum). At the taper period, control group continued with the same program. In contrast, both exponential groups had a diminution of training volume. Participants were tested in three periods (i.e., before and after the resistance training and after the tapering phase) for the determination of maximum repetition, squat jump and countermovement jump. Subjects answered to questionnaire of rating of perceived exertion after every training session. Results Resistance training showed a significant improvement of muscle strength and power in the three groups. However, in response to tapering phase, vertical jump performances and maximum repetition increased significantly only in both tapering groups. No significant difference was showed between exponential taper group and electrostimulation taper group after two weeks of taper.

Natural Frequency and Mode Shapes of Exponential Tapered AFG Beams on Elastic Foundation

A displacement based semi-analytical method is utilized to study non-linear free vibration and mode shapes of an exponential tapered axially functionally graded (AFG) beam resting on an elastic foundation. In the present study geometric nonlinearity induced through large displacement is taken care of by non-linear strain-displacement relations. The beam is considered to be slender to neglect the rotary inertia and shear deformation effects. In the present paper at first the static problem is solved through an iterative scheme using a relaxation parameter and later on the subsequent dynamic analysis is carried out as a standard eigen value problem. Energy principles are used for the formulation of both the problems. The static problem is solved by using minimum potential energy principle whereas in case of dynamic problem Hamilton’s principle is employed. The free vibrational frequencies are tabulated for exponential taper profile subject to various boundary conditions and foundation stiffness. The dynamic behaviour of the system is presented in the form of backbone curves in dimensionless frequency-amplitude plane and in some particular case the mode shape results are furnished.

A High-Gain Broadband Gradient Refractive Index Metasurface Lens Antenna

The design, simulation, and measurement results of a high-gain broadband gradient refractive index (GRIN) planar lens fed by an antipodal exponential taper slot antenna (ATSA) are presented. As a constituent part of this lens, a novel nonresonant metamaterial unit cell, composed of bilayer triple rectangular rings, is proposed and its equivalent circuit model is developed and described. It is shown that, by utilizing this element, stronger capacitive couplings between adjacent metallic layers are realized resulting in a large refractive index variation of about 2.5, and hence, a thin lens with a thickness of $0.38\lambda_{0}$ , where $\lambda_{0}$ is the wavelength at 9.5 GHz. In addition, since the unit cell is designed to resonate at higher frequencies, its refractive index response is smoothly increased over a broad frequency range and this considerably enhances the operating bandwidth of the lens. The achieved measured results demonstrate a broad matching and $-3\;{\rm dB}$ gain bandwidths of 52% (7–12 GHz) and 65% (7–13.2 GHz), respectively. Furthermore, this lens offers a high aperture efficiency of 50% (21.2 dB gain) at the center frequency, and its sidelobe and cross-polarization levels are less than $-20\;{\rm dB}$ and $-26\;{\rm dB}$ across the entire matched band, respectively.