Discrepancies In Absolute Values Research Articles

Experimental and numerical investigations on soil–water dynamics in Moistube irrigation under dynamically regulated working pressure heads: scenario simulations under maize cultivation

Moistube irrigation (MTI) accurately delivers moisture to root zone through subsurface nanotube irrigators. How to dynamically adjust the working pressure head (WPH) considering crop evapotranspiration remains unstudied. Here, the Moistube discharge characteristics, wetting front (WF) morphology, and soil water content (SWC) distribution under adjusted WPH (0 → 1, 0 → 2, 1 → 2, 1 → 0, 2 → 0 and 2 → 1 m) were experimentally investigated. HYDRUS 2D model was employed to reproduce the soil water dynamics and validated against the experimental data. Maize growth scenarios under regulated WPH for three representative regions (Nanjing, Hami, and Siping in China) with typical hydrological years were performed. The relatively long-term Moistube discharge, SWC, and deep percolation were analyzed. Results demonstrated that flexible WPH adjustment regulated Moistube discharge, the advance velocity of WF, and SWC within the wetting patterns. With increased (or decreased) WPH, the Moistube discharge rate precipitously raised (or descended) to values positively correlated with WPHs. WPHs of 0, 1, and 2 m corresponded to discharge rates of 0.63–0.76, 2.15–3.34, and 5.53–6.41 cm2 h−1, respectively. WF also noticeably accelerated (or decelerated) as WPH, meanwhile SWC within the wetting pattern increased (or decreased). Upon WPH increase, the elevated SWC intensified the deviation (δ) of wetting body centroid from Moistube. HYDRUS 2D model accurately reproduced the Moistube discharge rate and WF advance (R2 ≥ 0.90, NSE ≥ 0.70, RSR close to 0), corroborating the feasibility of treating Moistube as a heavy clay. Surprisingly, the Moistube discharge rate obeyed exponential decreasing trend over time after WPH increased but abnormally displayed restrained trends followed by rebounding after WPH decreased. SWC and the deviation of wetting body centroid from Moistube exhibited discrepancies in absolute values but consistencies in trends between the observed and simulated data. Scenario analyses of maize cultivation revealed that regulating WPH accurately replenished crop evapotranspiration and maintained appropriate SWC environments. Regulated WPH in MTI was efficacious in reducing deep percolation and suitable for arid regions. These results could contribute to intelligent MTI by automatically maintaining a balance between Moistube discharge and crop water requirements.

Benchmarking and validation of a hybrid model for electropositive and electronegative capacitively coupled plasmas

In this work, a fluid/Monte Carlo collision (fluid/MCC) hybrid model is developed based on the framework of multi-physics analysis of plasma sources. This hybrid model could be highly accurate in predicting the nonequilibrium phenomena in capacitively coupled plasmas and meanwhile avoid the limitation caused by the computational cost. Benchmarking against the well-established particle-in-cell/MCC (PIC/MCC) method and comparison with experimental data have been presented both in electropositive N2 discharges and electronegative O2 discharges. The results indicate that in N2 discharges, the ion density evolves from a uniform distribution to an edge-high profile as power increases. Besides, the electron energy distribution function (EEDF) at the bulk center exhibits a ‘hole’ at about 3 eV, and the ‘hole’ becomes less obvious at the radial edge, because more low energy electrons are generated there. In O2 discharges, the EEDF exhibits a Druyvesteyn-like distribution in the bulk region, and it evolves to a Maxwellian distribution in the sheath, indicating the dominant influence of the electric field heating there. The results obtained by the hybrid model agree well with those calculated by the PIC/MCC method, as well as those measured by double probe, except for a slight discrepancy in absolute values. The qualitative agreement achieved in this work validates the potential of this hybrid model as an effective tool in the deep understanding of plasma properties, as well as in the improvement of plasma processing.

The discrepancy between expenditure- and income-side estimates of US output

The United States has two measures of economic output: gross domestic product (GDP) and gross domestic income (GDI). While these are conceptually equivalent, their initial estimates differ because these initial estimates are computed from different and incomplete data sources. I study the difference, or “statistical discrepancy,” between GDP and GDI in percent and document three features. First, its size does not materially shrink on average as more data become available. Second, the size of the initial discrepancy in absolute value does not predict the size of the discrepancy in absolute value after revisions. Third, the initial discrepancy has some predictive information about revisions to lagged GDP growth but no predictive information about revisions to lagged GDI growth.

Identification of Pacejka model parameters of a light commercial vehicle tire for dynamic research

This article is devoted to the research of the interaction of the wheel of a GAZ light commercial vehicle with a hard supporting surface. The relevance of this problem is due to the need to adequately reproduce the force reactions acting on the tire in the contact patch, when modelling the vehicle dynamics. High similarity of the real process and its modelling are guaranteed if there is a significant empirical data set for a particular tire model, which can be ensured only by the results of field tests. Specialists from Nizhniy Novgorod State Technical University have developed a schematic diagram of a road measuring unit, a test methodology and built testing unit as well as conducted full-scale tests. The experiment was conducted in the auto racing track at an ambient air temperature of 20 °C on a dry road asphalt surface with a high friction coefficient (0.4 - 0.8). The resulting array of experimental data was processed and presented in numerical trigonometric polynomials form (PAC 2002). The table comparing theoretical and experimental values presented in the results of this article confirms the high level of convergence. The maximum discrepancy in absolute value does not exceed 5%.

Experimental and numerical investigations on time-resolved characteristics of pulsed inductively coupled O2/Ar plasmas

The time-resolved characteristics of pulsed inductively coupled O2/Ar plasmas have been investigated in this paper, by means of a Langmuir probe and a global model. The plasma properties, e.g., the electron density, effective electron temperature, and electron energy probability function (EEPF), have been experimentally investigated under various discharge conditions, combined with the comparison with simulated results. It is found that when the power is switched on, the electron density increases rapidly and then it reaches to a steady state with a constant value. When the power is switched off, the electron density exhibits a peak at the initial afterglow period, and then it decays gradually to a very low value. This peak may be caused by the detachment of negative ions. Moreover, it is noted that the effective electron temperature also increases to a peak value at the early afterglow, which can be understood by examining the evolution of EEPFs with time. Indeed, when the power is switched off, more moderate-energy electrons are produced through the collisions among the excited state particles and the energy loss of energetic electrons, and this is responsible for the peak of the effective electron temperature at the initial afterglow. In addition, the simulated results show a qualitative agreement with the experimental data, with the exception of the peaks in the electron density and effective electron temperature in the afterglow. The discrepancy in absolute values may be caused by the assumption of a Maxwellian electron energy distribution function distribution in the model.

A technique to predict the aerodynamic effects of battle damage on an aircraft’s wing

Abstract A technique is developed that can be used to predict the effects of battle damage on the aerodynamic performance of an aircraft’s wing. The technique is based on results obtained from wind tunnel tests on a NASA LS(1)-0417MOD aerofoil with simulated gunfire damage. The wind tunnel model incorporated an internal cavity to represent typical aircraft construction and this was located between 24% and 75% of chord. The damage was simulated by circular holes with diameters between 20% and 40% of chord. To represent different attack directions, the inclination of the hole axis relative to the aerofoil chord was varied between ±60° pitch and 45° of roll. The aerofoil spanned the wind tunnel to create approximate two-dimensional conditions and balance measurements were carried out at a Reynolds number of 500,000 for incidences, increased in 2° increments, from –4° to 16°. Surface flow visualisation and pressure measurements were also carried out. For a given hole size, the increments in lift, drag and pitching moment coefficients produced trends when plotted against the difference between the upper and lower surface pressure coefficients on the undamaged aerofoil taken at the location of the damage. These trends are used as the basis of the predictive technique. The technique is used to predict the effects of a previously untested damage case, and these are compared with wind tunnel tests carried out on a half model finite aspect ratio wing. For all coefficients the trends in the predicted data are similar to experiment, although there are some discrepancies in absolute values. For the drag coefficient these discrepancies are partly accounted for by limitations in the technique, whilst discrepancies in the lift and pitching moment coefficients are attributed to limitations in the aerofoil test arrangements.

Comparison of fast ion collective Thomson scattering measurements at ASDEX Upgrade with numerical simulations

Collective Thomson scattering (CTS) experiments were carried out at ASDEX Upgrade to measure the one-dimensional velocity distribution functions of fast ion populations. These measurements are compared with simulations using the codes TRANSP/NUBEAM and ASCOT for two different neutral beam injection (NBI) configurations: two NBI sources and only one NBI source. The measured CTS spectra as well as the inferred one-dimensional fast ion velocity distribution functions are clearly asymmetric as a consequence of the anisotropy of the beam ion populations and the selected geometry of the experiment. As expected, the one-beam configuration can clearly be distinguished from the two-beam configuration. The fast ion population is smaller and the asymmetry is less pronounced for the one-beam configuration. Salient features of the numerical simulation results agree with the CTS measurements while quantitative discrepancies in absolute values and gradients are found.

Global cloud‐system‐resolving simulation of aerosol effect on warm clouds

We simulated the interactions of aerosols with liquid clouds using an aerosol‐coupled global cloud‐system‐resolving model with horizontal resolution of 7 km, and the results are compared with satellite observations of cloud and aerosols. The result shows detailed spatial structures of cloud droplet effective radii (CDR) realistically simulated especially over tropics. The global correlation statistics of liquid water path (LWP) with aerosol index (AI) are investigated for different cloud types to reveal that the LWP slightly decreases with increasing AI, closely resembling satellite‐observed features. The CDRs for different cloud types are also shown to decrease with increasing AI, and the sensitivities are found to be relatively similar among cloud types although of discrepancy in absolute values between the model and satellite observation. The model also simulates vertical growth patterns of liquid droplets and their interactions with aerosols in a manner similar to satellite observations.

Development of a radiotransporter assay for determination of iodide: preliminary studies

Background: The principle of the radiotransporter assay (RATRA) is that the concentration of the substance to be assayed (analyte) is determined by the degree of its competitive inhibition of the binding of radioactive analyte with transporter. Methods: To illustrate this approach, the iodide concentrations in urine samples were determined by means of RATRA using Na +/I − symporter (NIS). Results: Iodide concentrations ranging from 9×10 −6 to 9×10 −4 mol/l could be measured without any significant interference of 0.85 mol/l NaCl. The mean recovery rate of added iodide to urine was 96.5%, serial dilutions of urine samples gave almost straight dose response lines passing near the zero point, the mean within assay coefficient of variation (CV) was 8.8% and between assay CV was 12.9%. Although urinary iodide concentrations determined by RATRA correlated with those using a chemical method ( r=0.97) and an electrode method ( r=0.85), there were discrepancies in absolute values particularly at the low level among these. Conclusions: The RATRA may have a limitation with respect to the specificity for determining analytes in the biological materials, but we suggest it has the ability to detect some factors influencing the transport.

A study of the line width in the rotational spectrum of methylfluoride

The results of a study on the line width in the pure rotational spectrum of methylfluoride are presented. The experimental values of the normalized line width as a function of the line number show a maximum at m = 16. There is good qualitative agreement with the theoretical results obtained with the quantum mechanical theory of Murphy and Boggs, although there remains a discrepancy in absolute value. An important result is that the Murphy and Boggs theory predicts quite accurately the temperature dependence of the line width.

Annihilation in flight of 200 and 800 MeV positrons

The total cross-sections for annihilation in flight of 200 and 800 MeV positrons have been measured. The ratio of the two cross-sections has been determined to an accuracy of 2.5% and is in accord with theory, while their absolute values are about (5±2.5)% low. From the measured ratio, there is no evidence for a deviation from theory which depends on the momentum transfer. The possible discrepancy in absolute value may arise from systematic corrections to the experiment.

Kinetic salt effects on the inversion of sucrose

The rate of inversion of sucrose by strong acids has been measured at 24·7° C by a method which eliminated the mutarotation lag and the end-point uncertainty. The rate was proved to be strictly first order for at least 54 hr. and the first-order rate constant was determined with an internal consistency better than 1%. In 0·1 M hydrochloric acid the first-order rate constantk1is linear inS, the number of grams of sucrose in a litre, according to the formulak1x 104/min.-1= 7·13 + 0·97 x 10-2S. For sucrose at 30 g./l. hydrolysed by single strong acids at molarities up to 0·2, the first order rate constantk1is related to the molaritycof strong acids by the formulak1min.-1= 6·95 x 10-3cx 10Bje, whereBjis a constant determined by the anion as follows: Cl¯, 0·28; Br¯, 0·35; ClO¯4, 0·38; NO¯3, 0·30. In similar experiments with mixed strong acids or a strong acid with the addition of a neutral uni-univalent salt, the experimental results can be expressed by the formulak1min.-1= 6.95 x 10¯3CHx 10ΣBjcj, whereCHdenotes the molarity of strong acids andcjthe molarity of each anion. EachBjhas the same value as in the formula for single acids. This formula is in accordance with Brönsted’s principle of specific interaction. In experiments on solutions containing bi-univalent and tri-univalent salts there is a further small negative salt effect of the multivalent cations increasing with their valency. This effect indicates that the principle of specific interaction becomes detectably inaccurate at these higher ionic strengths. Our results are compared with those of other workers. On the whole there is good agreement within the experimental accuracy of the various data. Certain discrepancies in absolute values of the rates are probably attributable to uncertainties of 0·1° C or less in the temperature.