Conditional Sampling Technique Research Articles

The Effect of Double Triangle and Double Square Trainings on Passing Results in Disporasu Football Players Aged 10-11

This research aims to determine the effect of double triangle and double square training on passing results in football players aged 10-11 years at Disporasu Football School (FS) in 2022. The research method used is an experimental method, namely to see a change from before treatment and after treatment and then in compare. This research uses a research design, namely one group pretest-posttest design. This research has a population of 18 people from the entire 10-11 year age category in Disporasu FS in 2022, to make it easier in the research the researcher has certain criteria, then the sample is taken using a purposive sample technique, namely a conditional sampling technique, so it can be obtained The sample was 14 people. The time of this research was carried out 18 meetings. The data collection techniques used in this research are tests and measurements. The test instrument used in this research was the football short pass test. The data analysis technique used is the normality test, the results of the pretest data normality test are Lcount 0.1493 and posttest data 0.1472 with Ltable 0.227 with the conclusion that the data is normally distributed, homogeneity test, the data homogeneity test results state that Fcount is 1.21 with Ftable 2 .58, then the conclusion that can be drawn is that the data comes from homogeneous variance and the t test with the help of SPSS 21. The results of the t-test state that there is a value of Tcount=16.60442, then the value of Tcount is compared with the value of Ttable with dk=n-1 (dk=14-1=13) at a significance level of ά=0.05, so we get Ttable=2 .16037, so that based on the hypothesis testing criteria it is stated that at Tcount=16.60442 > Ttable=2.16037, so Ho was accepted.

Fast-sampling fast-ion D-alpha measurement using multi-anode photomultiplier tube in large helical device.

A fast-sampling fast-ion D-alpha (F-FIDA) measurement has been developed in the large helical device in order to investigate fast ion dynamics associated with helically trapped fast-ion-driven Magnetohydrodynamic (MHD) bursts. F-FIDA consists of a multi-anode photomultiplier tube (PMT) and achieves a sampling rate of 10kHz. During the deuterium experiment campaign in 2022, F-FIDA measured the spectrum of perpendicular fast ions, using perpendicular lines of sight. We compared F-FIDA with conventional FIDA, using an electron multiplying charge coupled device, and confirmed that the time-averaged images were generally consistent between the two. The statistical properties of the temporal evolution associated with MHD bursts were analyzed using a conditional sampling technique. The results showed that the PMT signal varied in different spatial and wavelength channels. Although the signal-to-noise ratio was poor and there was room for improvement, it could provide useful information for studies on the phase-space dynamics of fast ions.

Determinan Transfer Pricing Pada Perusahaan Pertambangan Di Indonesia (Study Multy Years pada Perusahaan yang Terdaftar pada Bursa Efek Indonesia tahun 2019-2021)

This study was conducted to find out how to determine transfer pricing in mining companies listed on the IDX. The study used quantitative methods with purposive sampling, namely conditional sampling techniques. From the results of the study, it can be concluded that company size, Leverage Ratio, bonus mechanism, Intangible Assets, and Profitability partially have a significant effect on the company's transfer pricing, while Tunneling Incentives and Multinationality partially have no significant effect on the company's transfer pricing. Simultaneously, Company size, Leverage ratio, bonus mechanism, Tunneling Incentives, multinationality, intangible assets and profitability have a significant effect on the transfer pricing of Mining Companies in Indonesia which are listed on the IDX in a row during the 2015-2019 period.

Integrated Quadrant Analysis: A New Method for Analyzing Turbulent Coherent Structures

Integrated quadrant analysis is a novel technique to identify and to characterize the trajectory and strength of turbulent coherent structures in the atmospheric surface layer. By integrating the three-dimensional velocity field characterized by traditional quadrant analysis with respect to time, the trajectory history of individual coherent structures can be preserved with Eulerian turbulence measurements. We develop a method to identify the ejection phase of coherent structures based on turbulence kinetic energy (TKE). Identifying coherent structures within a time series using TKE performs better than identifying them with the streamwise and vertical velocity components because some coherent structures are dominated by the cross-stream velocity component as they pass the sensor. By combining this identification method with the integrated quadrant analysis, one can animate or plot the trajectory of individual coherent structures from high-frequency velocity measurements. This procedure links a coherent ejection with the subsequent sweep and quiescent period in time to visualize and quantify the strength and the duration of a coherent structure. We develop and verify the method of integrated quadrant analysis with data from two field studies: the Eclipse Boundary Layer Experiment (EBLE) in Corvallis, Oregon in August 2017 (grass field) and the Vertical Cherry Array Experiment (VACE) in Linden, California in November 2019 (cherry orchard). The combined TKE identification method and integrated quadrant analysis are promising additions to conditional sampling techniques and coherent structure characterization because the identify coherent structures and couple the sweep and ejection components in space. In an orchard (VACE), integrated quadrant analysis verifies each coherent structure is dominated by a sweep. Conversely, above the roughness sublayer (EBLE), each coherent structure is dominated by an ejection.

Uses and Gratification on Virtual Purchase Behavior of Mobile Game Items: An Alternative Approach

This study aims to predict the behavior of purchase decisions for virtual goods, especially for PUBG Mobile game players, using a use and gratification approach, as well as perceived value as mediation. The population of this research is PUBG Mobile game players. The conditional sampling technique or purposive sampling amounted to 206 respondents. Samples are game players who have purchased virtual goods. Data analysis using SEM PLS. The results show that utilitarian gratification has the most influence on the PUBG virtual item top-up decision. The contribution of the mediating variable, namely the perceived value, did not succeed in increasing the influence of the independent variable on the topup decision. The research results are expected to be one of the product development strategies for game developers.

Wall-Shear-Stress-Based Conditional Sampling Analysis of Coherent Structures in a Turbulent Boundary Layer

Abstract Coherent structures are critical for controlling turbulent boundary layers due to their roles in momentum and heat transfer in the flow. Turbulent coherent structures can be detected by measuring wall shear stresses that are footprints of coherent structures. In this study, wall shear stress fluctuations were measured simultaneously in a zero pressure gradient turbulent boundary layer using two house-made wall shear stress probes aligned in the spanwise direction. The wall shear stress probe consisted of two hot-wires on the wall aligned in a V-shaped configuration for measuring streamwise and spanwise shear stresses, and their performance was validated in comparison with a direct numerical simulation result. Relationships between measured wall shear stress fluctuations and streamwise velocity fluctuations were analyzed using conditional sampling techniques. The peak detection method and the variable-interval time-averaging (VITA) method showed that quasi-streamwise vortices were inclined toward the streamwise direction. When events were simultaneously detected by the two probes, stronger fluctuations in streamwise velocity were detected, which suggests that stronger coherent structures were detected. In contrast to the former two methods, the hibernating event detection method detects events with lower wall shear stress fluctuations. The ensemble-averaged mean velocity profile of hibernating events was shifted upward compared to the law of the wall, which suggests low drag status of the coherent structures related with hibernating events. These methods suggest significant correlations between wall shear stress fluctuations and coherent structures, which could motivate flow control strategies to fully exploit these correlations.

Characterizing time intermittency in non-diffusive fast ion transport through plasma turbulence

Turbulent fast ion transport has been investigated in astrophisycal, laboratory and fusion plasmas. When gyro- and drift-averaging across plasma structures manifest as non-markovian and non-local effects, this results in generally non-diffusive transport. The intermittency of the formation of these plasma structures, such as blobs, can potentially be reflected in the transport of the fast ions as well. In the TORPEX basic plasma device, a toroidal beam of suprathermal Li-6 ions is injected into electrostatic plasma turbulence. Conditional sampling techniques confirm turbulent E × B-drifts as physical driving mechanism of radial fast ion transport, which features sub-, super- or quasi-diffusive regimes depending on the fast ion energy and propagation time. To address the question of how far local intermittency is associated with each regime, we analyze characteristics of time-intermittency on an extensive set of local fast ion time-series across all observed regimes. Modeling the time-average fast ion profiles as the result of a meandering smaller instantaneous beam allows us to predict the skewness of such time-series based on their time-average. Comparisons with the skewness of simple two-valued time-series can yield relative indications towards certain transport regimes in our specific system, based on the differences in the size of the instantaneous fast ion beam.

Statistical analysis of temperature distribution on vortex surfaces in hypersonic turbulent boundary layer

The nonuniform temperature distribution (NUTD) on the coherent vortex surfaces of hypersonic turbulent boundary layer (TBL) is studied using the conditional sampling technique. The direct numerical simulation data of Mach 8 flat-plate TBL flows with different wall temperatures, Tw/T∞ = 10.03 and 1.9, are used for this research, and the coherent vortex surface is identified by the Ω-criterion. Two characteristic sides of the vortex are defined, which are represented by the positive and negative streamwise velocity fluctuations (±u′) of the vortex surfaces. The conditional sampling results between the mean temperature of the two sides show that there is a significant difference of up to 20% at the same wall-normal location. Furthermore, the velocity-temperature fluctuation correlations (Ru′T′ and Rv′T′) at the characteristic sides of vortex surfaces are studied. It is found that the temperature fluctuations are redistributed by the vortex rotational motion that has taken effect through Ru′T′ and Rv′T′ and then lead to the NUTD. The NUTD features are changed quantitatively by wall cooling but share the similar mechanism as that of the higher-temperature case.

An experimental investigation into spatiotemporal intermittencies in turbulent channel flow close to transition

Experiments are presented to characterize low- and high-drag turbulence events in channel flows close to transition, which last for a certain duration, at friction Reynolds numbers ranging from Re_tau,=, 70–100. The spatiotemporal intermittencies are identified by applying conditional sampling techniques to simultaneously acquired wall shear stress and velocity data using either single-point laser Doppler velocimetry (LDV) or stereoscopic particle image velocimetry (SPIV). It is shown that ensemble-averaged streamwise velocity during intervals of low drag fall close to a recently discovered exact coherent state (ECS), in agreement with recent direct numerical simulation (DNS) results. The low-drag intervals are characterized by a low-stress streak which is flanked on either side by a streamwise vortex, forming a counter-rotating vortex pair. Ensemble-averaged streamwise velocity during intervals of high drag fall further below the Prandtl–von Kármán log-law with increasing Reynolds number. Generally, higher levels of turbulence intensity are observed during intervals of low drag when compared to similar intervals of high drag.Graphical abstract

Experimental investigation on destruction of Reynolds stress in a plane jet

Flow structures that cause destruction of the Reynolds (shear) stress are investigated by means of simultaneous measurement of the velocity gradient and pressure. Two types of combined probes are used for the simultaneous measurement of the velocity gradient and pressure. One consists of an X-type hot-wire probe and a pressure probe; another consists of two I-type hot-wire probes arranged in parallel with a small vertical separation (double-I) and a pressure probe. The hot-wire probe and the pressure probe are aligned along the streamwise direction for both combined probes. We confirm that the simultaneous measurement of the velocity gradient and pressure in a plane jet is satisfactorily performed using the combined probes, except for the outside of the velocity half-width. In a plane jet, $$\overline{(p'/\rho )(\partial u'_{2}/\partial x_{1})}$$ does not contribute to the Reynolds stress destruction, so that the total pressure-rate-of-strain correlation is almost equal to $$\overline{(p'/\rho )(\partial u'_{1}/\partial x_{2})}$$ . The flow structures that destruct the Reynolds stress are extracted by the conditional sampling technique. We find two structures, which support the thought experiment conducted by Hinze (Turbulence, 2nd edn, McGraw-Hill College, Pennsylvania, 1975). The structures are concentrated around large-scale vortex structures, which cause strong momentum transfer. The scale of the structures is intermediate: smaller than large-scale motion contributing to the momentum transfer, and larger than small-scale motion contributing to the energy dissipation.

Study on Vortex Structure in the Wake behind Circular Disk by Stereo PIV and Conditional Sampling Technique

Study on Vortex Structure in the Wake behind Circular Disk by Stereo PIV and Conditional Sampling Technique

Direct numerical simulation of turbulent flow above zigzag riblets

We investigate the drag-reducing performance of a zigzag riblet inspired by the “Miura fold” and its influence on the streamwise vortices above a wall-bounded turbulent flow through direct numerical simulations of channel flows. The employed channel wall geometries are a flat plate, straight riblet, and zigzag riblet. The drag-reducing performance of various zigzag riblets with adjusted configuration parameters is superior or at least comparable to that of the straight riblet. We assume an analogy between the drag reduction mechanisms of spatially periodic forcing and the zigzag riblet, because both methods induce similar sinusoidal velocity profiles. To investigate the characteristics of the zigzag riblets, we apply a conditional sampling technique to the near-wall streamwise vortices that is also applied to the wall-bounded flow under spatially periodic forcing. The flow toward the wall of the rotating motion of a vortex becomes relatively small, as the main flow levitates at the tips of the zigzag riblet. Thus, the ejection increases and the sweep decreases. In the phase where the direction of the induced spanwise velocity coincides with the vortical motion, the latter is weakened because the vortex tilts in the spanwise direction at the phase; then, vortex stretching is suppressed. The zigzag riblet can reduce the drag via a mechanism analogous to active control, such as periodic oscillation. However, the effect of the upward flow is dominant above the zigzag riblet, and the analogous mechanisms are less remarkable. The considered zigzag riblet has potential application as a kind of active feedback control.

Across-wind excitation mechanism for interference of twin tall buildings in tandem arrangement

Excitation mechanism of interference effect between two tall buildings is investigated with wind tunnel experiments. Synchronized building surface pressure and flow field measurements by particle image velocimetry (PIV) are conducted to explore the relationship between the disturbed wind flow field and the consequent wind load modification for twin buildings in tandem. This reveals evident excitation mechanisms for the fluctuating across-wind loads on the buildings. For small distance (X/D 3), strong correlation between the across-wind load of the downstream building and the oscillation of the wake of the upstream building is found. By further analysis with conditional sampling and phase-averaged techniques, the coherent flow structures in the building gap are clearly observed and the wake oscillation of the upstream building is confirmed to be the reason of the magnified across-wind force on the downstream building. For efficient PIV measurement, the experiments use a square-section high-rise building model with geometry scale smaller than the usual value. Interference factors for all three components of wind loads on the building models being surrounded by another identical building with various configurations are measured and compared with those from previous studies made at large geometry scale. The results support that for interference effect between buildings with sharp corners, the length scale effect plays a minor role provided that the minimum Reynolds number requirement is met.

Internal state recovery of Grain v1 employing guess‐and‐determine attack

The well-known stream cipher Grain v1 is one of the finalists of European eSTREAM project. In this study, a novel guess-and-determine attack on Grain v1 is introduced. The attack primarily employs a new conditional BSW sampling technique and the main creative idea is that the conditions are set not only on state bits but also on the updates of the registers for the BSW sampling technique. It is shown that using this technique we can further reduce the sampling resistance of Grain v1 to which is the best result so far. The attack leads to an efficient internal state recovery of Grain v1 with only online time employing a memory of , requiring keystreams each of length and preprocessing time. It is shown that these figures are obviously better compared with the previous results. This is also the first attempt to control the updates of the registers of Grain v1 in the guess-and-determine attack and hopefully this provides new insights for cryptanalysis on such compact stream ciphers.

Spatiotemporal dynamics of viscoelastic turbulence in transitional channel flow

Direct numerical simulations (DNS) of viscoelastic turbulence in channel flow are performed in minimal and large domains and the dynamics in the two cases are compared. Friction Reynolds numbers ranging from 70 to 100 and in the zero to moderate (40%) drag reduction (DR) regimes are studied. In minimal domains, there are occasional time intervals when the flow exhibits features such as weak vortices, low Reynolds shear stress, lower friction drag and larger log-law slope; these have been denoted as “hibernating turbulence” in contrast to the “active turbulence” that occurs otherwise. The present study addresses the question of whether similar low-drag events arise spatiotemporally in large domains. Image analysis algorithms and conditional sampling techniques are applied to the extended domains to identify and quantify the spatially local low-drag or hibernating regions. The results indicate that the hibernating states found in large domains share many similarities with those in minimal domains. Not only are their flow structures similar, but how they evolve with Reynolds number and viscoelasticity is qualitatively identical. In both large and minimal domains, structures in hibernating intervals/regions remain virtually unaltered with increasing viscoelasticity and the polymer molecules are less stretched than in active regions. At fixed Weissenberg number the hibernating regions/intervals vanish as friction Reynolds number increases; however they reappear as viscoelasticity is introduced, and gradually dominate the flow fields at sufficiently high Weissenberg number.

Study of runaway electrons using the conditional average sampling method in the Damavand tokamak

Some experiments for studying the runaway electron (RE) effects have been performed using the poloidal magnetic probes system installed around the plasma column in the Damavand tokamak. In these experiments, the so-called runaway-dominated discharges were considered in which the main part of the plasma current is carried by REs. The induced magnetic effects on the poloidal pickup coils signals are observed simultaneously with the Parail–Pogutse instability moments for REs and hard X-ray bursts. The output signals of all diagnostic systems enter the data acquisition system with 2 Msample/(s channel) sampling rate. The temporal evolution of the diagnostic signals is analyzed by the conditional average sampling (CAS) technique. The CASed profiles indicate RE collisions with the high-field-side plasma facing components at the instability moments. The investigation has been carried out for two discharge modes—low-toroidal-field (LTF) and high-toroidal-field (HTF) ones—related to both up and down limits of the toroidal magnetic field in the Damavand tokamak and their comparison has shown that the RE confinement is better in HTF discharges.

Steady and unsteady mixed convection flow in a cubical open cavity with the bottom wall heated

In this study we analyze experiments and numerical simulations of steady and unsteady mixed convection flow in a cubical cavity located at the bottom of a square channel. The Reynolds numbers based on the mean flow velocity and the channel width are in the range 100⩽Re⩽1500 and the Richardson numbers vary within 0.1⩽Ri⩽10. Particle Image Velocimetry has been used for the measurements in a water channel. Three-dimensional direct numerical simulations have been carried out with a second order finite volume code considering the Boussinesq approximation since, for the experimental conditions considered, the variation of the physical properties with temperature has no significant influence on the overall flow topology. For 100⩽Re⩽1500 and Ri⩽0.1 the flow is steady and it consists in a single roll that exhibits larger velocities as the Richardson number is increased. An unsteady periodic flow is found at Re=100 and Ri=10. Alternate flow ejections from the cavity to the channel occur near the lateral walls while the flow enters the cavity from the channel through the central part of the cavity. A conditional sampling technique has been used to elucidate the evolution of the mean unsteady turbulent flow at Ri=10. It has been found that the alternate flow ejections persist for all the Reynolds analyzed. The computed Nusselt numbers are in general agreement with a previously reported correlation, valid for two dimensional cavities of different aspects ratios.

Simultaneous measurement of velocity and pressure near the turbulent/non-turbulent interface of a planar turbulent jet

Simultaneous measurement of velocity and pressure near the interface of turbulent/non-turbulent region of a planar turbulent jet is performed. Simultaneous measurement is achieved by means of a combined probe comprising an X-type hot-wire and a static pressure probe. The measurement data are analyzed by the conditional sampling technique and the ensemble-averaging technique on the basis of the intermittency function for the turbulent/non-turbulent decision. Obtained results show that there is a thin interfacial layer between the turbulent/non-turbulent region accompanied with the rapidly changing of velocity, Reynolds stress, and pressure. The thickness of the interfacial layer is 0.08 times the half-width of the cross-streamwise profile of the mean streamwise velocity and almost the same as Taylor transverse micro scale at the measurement position. Further, the velocity and pressure field near the interfacial layer indicates the existence of vortices whose core is at the middle of the interfacial layer and its diameter is the same as the thickness of the interfacial layer. The turbulent energy production and diffusion near the interface are also investigated by estimating the production term and the diffusion term in the transport equation for the turbulent energy. Estimated results show that the turbulent energy is transported from the turbulent region to the outer non-turbulent region by the pressure diffusion. Therefore, the existence of the vortices near the interface has an important role to transport the turbulent energy to the outer non-turbulent region.

Diffusion Process of High Concentration Spikes in a Quasi-Homogeneous Turbulent Flow

When a mass spreads in a turbulent flow, areas with obviously high concentration of the mass compared with surrounding areas are formed by organized structures of turbulence. In this study, we extract the high concentration areas and investigate their diffusion process. For this purpose, a combination of Planar Laser Induced Fluorescence (PLIF) and Particle Image Velocimetry (PIV) techniques was employed to obtain simultaneously the two fields of the concentration of injected dye and of the velocity in a water turbulent channel flow. With focusing on a quasi-homogeneous turbulence in the channel central region, a series of PLIF and PIV images were acquired at several different downstream positions. We applied a conditional sampling technique to the PLIF images to extract the high concentration areas, or spikes, and calculated the conditional-averaged statistics of the extracted areas such as length scale, mean concentration, and turbulent diffusion coefficient. We found that the averaged length scale was constant with downstream distance from the diffusion source and was smaller than integral scale of the turbulent eddies. The spanwise distribution of the mean concentration was basically Gaussian, and the spanwise width of the spikes increased linearly with downstream distance from the diffusion source. Moreover, the turbulent diffusion coefficient was found to increase in proportion to the spanwise distance from the source. These results reveal aspects different from those of regular mass diffusion and let us conclude that the diffusion process of the spikes differs from that of regular mass diffusion.

The influence of warm-season precipitation on the diel cycle of the surface energy balance and carbon dioxide at a Colorado subalpine forest site

Abstract. Precipitation changes the physical and biological characteristics of an ecosystem. Using a precipitation-based conditional sampling technique and a 14 year data set from a 25 m micrometeorological tower in a high-elevation subalpine forest, we examined how warm-season precipitation affected the above-canopy diel cycle of wind and turbulence, net radiation Rnet, ecosystem eddy covariance fluxes (sensible heat H, latent heat LE, and CO2 net ecosystem exchange NEE) and vertical profiles of scalars (air temperature Ta, specific humidity q, and CO2 dry mole fraction χc). This analysis allowed us to examine how precipitation modified these variables from hourly (i.e., the diel cycle) to multi-day time-scales (i.e., typical of a weather-system frontal passage). During mid-day we found the following: (i) even though precipitation caused mean changes on the order of 50–70 % to Rnet, H, and LE, the surface energy balance (SEB) was relatively insensitive to precipitation with mid-day closure values ranging between 90 and 110 %, and (ii) compared to a typical dry day, a day following a rainy day was characterized by increased ecosystem uptake of CO2 (NEE increased by ≈ 10 %), enhanced evaporative cooling (mid-day LE increased by ≈ 30 W m−2), and a smaller amount of sensible heat transfer (mid-day H decreased by ≈ 70 W m−2). Based on the mean diel cycle, the evaporative contribution to total evapotranspiration was, on average, around 6 % in dry conditions and between 15 and 25 % in partially wet conditions. Furthermore, increased LE lasted at least 18 h following a rain event. At night, even though precipitation (and accompanying clouds) reduced the magnitude of Rnet, LE increased from ≈ 10 to over 20 W m−2 due to increased evaporation. Any effect of precipitation on the nocturnal SEB closure and NEE was overshadowed by atmospheric phenomena such as horizontal advection and decoupling that create measurement difficulties. Above-canopy mean χc during wet conditions was found to be about 2–3 μmol mol−1 larger than χc on dry days. This difference was fairly constant over the full diel cycle suggesting that it was due to synoptic weather patterns (different air masses and/or effects of barometric pressure). Finally, the effect of clouds on the timing and magnitude of daytime ecosystem fluxes is described.