Simple Empirical Approach Research Articles

Effect of Film Diffusion on the Ion-Exchange Kinetics of a Tracer Ion in Nafion-117 Membrane from a Mixture of Salt Solution.

The ion-exchange kinetics of a tracer ion (Cs+ and Ba2+) in presence of a bulk ion (Na+/H+) has been measured in Nafion-117 membrane for a range of concentrations of NaCl/HNO3 using the nonstationary radiotracer method. A systematic increase in the ion-exchange rate and decrease in the partition coefficients of the tracer ions between membrane and solution have been observed with the increase in bulk ion concentration. The sigmoidal nature of experimental profiles indicates film-diffusion-controlled kinetics even for well-stirred solutions. In the absence of an existing analytical or numerical solution, a simple empirical approach has been proposed to find the variable membrane surface concentration and has been used to solve the membrane diffusion equation by the finite difference method. The fitting of the experimental curves with a single diffusion coefficient for Cs+/Ba2+ has been achieved. The exchange rate has been found to be independent of the stirring speed beyond a limiting speed.

CHOOSING OF OPTIMAL REFERENCE SAMPLES FOR BOREAL LAKE CHLOROPHYLL A CONCENTRATION MODELING USING AERIAL HYPERSPECTRAL DATA

Abstract. Optical remote sensing has potential to overcome the limitations of point estimations of lake water quality by providing spatial and temporal information. In open ocean waters the optical properties are dominated by phytoplankton density, while the relationship between color and the constituents is more complicated in inland waters varying regionally and seasonally. Concerning the difficulties relating to comprehensive modeling of complex inland and coastal waters, the alternative approach is considered in this paper: the raw digital numbers (DN) recorded using aerial remote hyperspectral sensing are used without corrections and derived by means of regression modeling to predict Chlorophyll a (Chl-a) concentrations using in situ reference measurements. The target of this study is to estimate which number of local reference measurements is adequate for producing reliable statistical model to predict Chl-a concentration in complex lake water ecosystem. Based on the data collected from boreal lake Lohjanjärvi, the effect of standard deviation of Chl-a concentration of reference samples and their local clustering on predictability of model increases when number of reference samples or bands used as model variables decreases. However, the 2 or 3 band models are beneficial and more cost efficient when compared to 5 or 7 band models when the standard deviation of Chl-a concentration of reference samples is over certain level. The simple empirical approach combining remote sensing and traditional sampling may be feasible for regional and seasonal retrieval of Chl-a concentration distributions in complex ecosystems, where the comprehensive models are difficult or even impossible to derive.

The long-term interaction of mine tailings with soils and the wider environment: Examples from Mont Chemin, Switzerland

There is no doubt that mine tailings and waste are an environmental problem and can be a risk to human health and other organisms. Although many studies about acid rock drainage have been performed, the dispersal of trace elements and their impact on the environment (groundwater, soils and agricultural use) and the long-term (i.e., decades to centuries) behaviour of mine tailings on silicate parent rock is still a matter of debate. Our main scope was, therefore, to develop an approach that enables a relatively fast and reliable prediction of the leaching of potentially toxic elements and, thus, to determine the reactivity of former mining sites. To do so, we traced back the leaching behaviour of metals such as copper (Cu), chromium (Cr), cadmium (Cd) and lead (Pb) in soils formed on tailings from small mines over a relatively long time period. Using a chronosequence approach based on historical records of mining activities and C-14 dating, element leaching could be traced over a time period of approximately 1000years for the historic mining sites at Mont Chemin (Switzerland). The weathering index B, that expresses chemical leaching of base cations and weathering of silicate minerals, and trace element ratios to immobile compounds (such as hafnium (Hf)) indicated that element leaching, and thus reactivity of the material, was very intense during the first 200years after abandonment of the site. Between approximately 200–400years, the rate of elemental change in the soils was strongly reduced tending (moderate reactivity) to very small values, and consequently low reactivity, for exposure ages of >400years. Thus, the chronosequence approach enabled to determine the reactivity of the sites. Soil organic carbon and oxyhydroxides were not effective enough to completely retain trace metals. Many former small mining sites exist in the Swiss Alps. Using a database that contains information about the period of activity, date of abandonment, elements used and geology, we extrapolated our findings to sites in Switzerland with moderately comparable conditions to Mont Chemin. This relatively simple empirical approach enabled a spatialisation and rough estimation of the sites regarding their reactivity. A large number of small mining sites in Switzerland were characterised as still highly reactive and only a few were considered to be weakly reactive. With the help of the chronosequence approach and extrapolation of the small former mining sites, a relatively fast overview of the reactivity of sites could be achieved. This approach, however, cannot substitute for a detailed risk analysis of such sites.

A simple finding on variable amplitude (Gassner) fatigue SN curves obtained using Miner’s rule for unnotched or notched specimen

In this note, starting from the SN curve under Constant Amplitude (CA) for the fatigue life of the uncracked (plain) specimen, we obtain that Gassner curves for Variable Amplitude (VA) loading using the simple Palmgren-Miner’s law are simply shifted CA curves. Further, using the Critical Distance Method in a very clean and powerful form proposed by Susmel and Taylor for VA loading, we find similar result for notched specimen, the spectrum loading results in the same multiplicative term for notched, cracked and unnotched specimen. Hence, the present proposal can be considered as a simple empirical unified approach for rapid assessment of the notch effect under random loading, which simplifies the recent proposal by Susmel and Taylor. To their extensive validations, we add some specific comparison with experimental data from the Literature on our further findings.

Estimating daily root-zone soil moisture in snow-dominated regions using an empirical soil moisture diagnostic equation

Soil moisture in snow-dominated regions has many important applications including evapotranspiration estimation, flood forecasting, water resource and ecosystem services management, weather prediction and climate modeling, and quantification of denudation processes. A simple and robust empirical approach to estimate root-zone soil moisture in snow-dominated regions using a soil moisture diagnostic equation that incorporates snowfall and snowmelt processes is suggested and tested. A five-water-year dataset (10/1/2010–9/30/2015) of daily precipitation, air temperature, snow water equivalent and soil moistures at three depths (i.e., 5cm, 20cm, and 50cm) at each of 12 Snow Telemetry (SNOTEL) sites across Utah (37.583°N–41.883°N, 110.183°W–112.9°W), is applied to test the proposed method. The first three water years are designated as the parameter-estimation period (PEP) and the last two water years are chosen as the model-testing period (MTP). Applying the estimated soil moisture loss function parameters and other empirical parameters in the soil moisture diagnostic equation in the PEP, soil moistures in three soil columns (0–5cm, 0–20cm, and 0–50cm) are estimated in the MTP. The relatively accurate soil moisture estimations compared to the observations at 12 SNOTEL sites (RMSE⩽6.23 (%V/V), average RMSE=4.28 (%V/V), correlation coefficient ⩾0.75, average correlation coefficient =0.89, the Nash-Sutcliffe efficient coefficient Ec⩾0.24, average Ec=0.72) indicate that the soil moisture diagnostic equation is capable of accurately estimating soil moisture in snow-dominated regions after the snowfall and snowmelt processes are included in the soil moisture diagnostic equation.

Square‐Planar PtII versus Octahedral PtIV Halido Complexes: 195Pt NMR Explained by a Simple Empirical Approach

In this work, we show by a simple empirical approach that a linear relationship between observed 195Pt NMR frequencies and the overall sum of the ionic radii of the coordinated halido ligands [Σ(rh)] exists in square‐planar PtII complexes of the type [PtXnY4–n]2– (1 ≤ n ≤ 4; X, Y = Cl, Br, I). Another finding was that such square‐planar complexes could be empirically described as octahedral complexes, with the two lobes of the 5dz² orbital above and below the coordination plane acting as two pseudo‐halido ligands, each showing a constant apparent radius of around 207 pm. According to our approach, the overall apparent radius of around 415 pm produces constant 195Pt NMR shielding for all [PtXnY4–n]2– complexes of about 10450 ppm. This result is 1) consistent with the theoretically calculated overall 5d shell lone‐pair shielding observed in square‐planar PtII with respect to octahedral PtIV complexes and 2) almost coincident with the already measured chemical shift anisotropy (CSA) of the K2[PtCl4] complex both in solution and in the solid state (single crystal).

Empirical approach to develop synthetic unit hydrographs for ungauged Dhamani basin, Maharashtra (India)

The study aims to develop average representative unit hydrograph for Dhamani basin from the chosen storms. The best average representative unit hydrograph with minimum root mean square error is determined using leave one out cross validation method. The study further deals with empirical synthesis of unit hydrograph using Snyder's method, Mitchell's equation and Commons' method. A simple and rapid empirical approach of involving Buckingham pi theorem method is used to determine synthetic unit hydrograph parameters for the representative basin. The results attained by this approach are compared with the other synthetic methods. It is observed that, the peak discharge computed using Buckingham pi theorem method shows a good estimate with minimum percentage error (3.661%). The shape of the hydrograph gives good fit to the observed unit hydrograph amongst the other methods as it shows minimum deviation. This method offers a reasonable approach of determining peak discharge and shape of the hydrograph.

Settlement Prediction of Stone Column Group

Stone columns can be designed to bear on the hard stratum or as a floating system where the toe is embedded in the soft layer. Most of the existing design methods for stone columns adopt unit cell idealization which is not applicable to spread footing. From the view of settlement analyses, current available methods to evaluate the settlement performance of a footing on a limited number of stone columns are more or less rough approximations derived from the elastic theory or using simple empirical approach. None of these methods incorporate the idea of optimum length and the yielding effect in the plastic zone. This paper introduces a new mechanical method to account for these. This method works for homogenous and non-homogenous ground condition. The settlement predictions made by the proposed method are compared with the finite elements results and field measurement. Good agreements are obtained not only for load settlement response but also the displacement profile.

Development of Local IDF-formula Using Controlled Random Search Method for Global Optimization

The aim of the study is to present the effective and relatively simple empirical approach to rainfall intensity-duration-frequency-formulas development, based on Controlled Random Search (CRS) for global optimization. The approach is mainly dedicated to the cases in which the commonly used IDF-relationships do not provide satisfactory fit between simulations and observations, and more complex formulas with higher number of parameters are advisable. Precipitation data from Gdansk gauge station were analyzed as the example, with use of peak-overthreshold method and Chomicz scale for rainfall intensity. General forms of the IDF-function were chosen and the parameter calibration with use of CRS algorithm was developed. The compliance of the obtained IDFformulas with precipitation data and the efficiency of the algorithm were analyzed. The study confirmed the proposed empirical approach may be an interesting alternative for probabilistic ones, especially when IDFrelationship has more complex form and precipitation data do not match “typical” hydrological distributions.

Study on metastable zone width and crystal growth of a ternary system: case study MgCl2·6H2O·1,4-dioxane

The recovery of MgCl2 from brines and salt lakes by solvate crystallization as MgCl2·6H2O·1,4-dioxane with 1,4-dioxane was investigated. The metastable zone (MSZ) of MgCl2·6H2O·1,4-dioxane in the MgCl2-6H2O-1,4-dioxane system was studied using an IR probe in small scale (12mL) and an ultrasound velocity probe in large scale (120mL). It was experimentally observed that small scale (12mL) nucleation experiments were not reproducible, whereas large scale (120mL) experiments presented reliable results. The solubility data of the two polythermal methods were compared with a published isothermal method. The influence of volume on MSZW measurements is explained in detail. Crystal growth rates were also determined at different temperatures and supersaturation levels using a microscopic cell. To correlate the measured growth rate with species concentrations in solution, a simple empirical approach was proposed. The correlation presented is of interest for the calculation of growth rates when designing crystallization processes to separate the MgCl2·6H2O·1,4-dioxane from salt brines.

A Crash Severity-Based Black Spot Identification Model

The objective of this research is to develop a new black spot model incorporating the severity of crashes with high consistency. Crash history from 2005 to 2009 of the Ipswich Motorway, in Australia, was used to identify black spots by using simple ranking and empirical Bayes approach. The results of these analyses were then compared via two consistency tests. These tests revealed that for the simple ranking method and the empirical Bayes method, the crash type analysis was more consistent than the crash frequency analysis and the collective risk analysis. Further research into the validity of the proposed indicator would be recommended due to its incorporation of the crash severity and the high consistency it demonstrated in this study, both of which are of great benefit from a practical point of view.

An empirical analysis of energy shortage in Pakistan

In this paper, the electricity shortage in Pakistan is addressed through an examination of data over the period 1971-2010 with a time-series analysis. The novelty of the study lies in characterizing energy shortages using both an index comprising the demands for electricity, gas and oil, and information on the public electricity supply. This index allows for a simple empirical approach where energy shortages cannot be directly measured as data. The main findings are as follows: first, end consumers adjust their energy demands to prices only in the long run; second, the underutilization of installed power-generation capacity encourages fossil fuel consumption for private electricity; third, an uninterrupted electricity supply could be attained by regulating private electricity generation; and fourth, the relative demand for electricity increases with an increase in real income and then starts to decrease as income increases beyond the threshold of $1,127. Overall, the results of the study suggest that the price adjustment tactics adopted by the Government of Pakistan are not an effective policy to deal with power shortages in the short run. Rather, the Government should focus on improving the utilization rate of installed power plants and on rechannelling the use of oil and gas for public electricity generation. Otherwise, energy shortages will worsen with economic growth in Pakistan.

Empirical Bayes estimators of structural distribution of words in Lithuanian texts

Lithuanian language has great inflexion, free word order and other features which distinguish it from other languages. This raises a problem of testing for the Lithuanian language validity of findings established for other languages. In the paper, an empirical study of a collection of Lithuanian texts is performed. It is supposed that authors of texts are basic elements of the population under study and its heterogeneity stems out of the heterogeneity of preferences and choices of the authors. An attempt to estimate structural distributions of words in a collection of texts of different authors is made by making use of a simple statistical model and empirical Bayes approach.

Abstract 3747: Predicting Maximum Tolerated Dose during Phase I using anticipatory toxicity models

Abstract A critical component of the early development of anticancer agents is the assessment of the Maximum Tolerated Dose during Phase I. In practice, clinical toxicities are graded on a scale of severity, ranging from Grade 1 (least severe) to Grade 4. This categorical scale is also used for continuous readouts, such as neutropenia. As the underlying pathophysiology can be expected to remain the same, and vary by degree or intensity alone, the dose-response (or concentration- response) of lower-grade toxicities should foreshadow the incidence of higher-grade toxicities, which represent different thresholds on the same concentration-response curve. If the concentration- response of Grade 4 toxicity can be predicted from that of Grade 1 toxicity, then the accurate estimation of the MTD should be feasible from a careful estimation of the Grade 1 toxicity. In this work, we demonstrate the development of anticipatory toxicity models that are capable of predicting higher-grade toxicities during dose-escalation. First, we used a simple empirical approach that relies on a minimum of assumptions. We have previously shown that the nadir of neutropenia is strongly correlated with the maximum moving average concentration over the dosing window. Using this pharmacokinetic parameter as an independent variable, we developed a set of analytical expressions to connect the concentration- response of each lower grade of toxicity to the corresponding higher grades of toxicity. Next, we tested this family of anticipatory toxicity models on a simulated dataset of neutropenia generated from a previously published model of clinical neutropenia for a range of chemotherapeutics (Friberg et al., 2002). Finally, we validated our anticipatory toxicity models with in-house preclinical data. Next, we extended the development of anticipatory toxicity models to a model-based approach. We fitted the lower grades of toxicity from the simulated dataset described above to fit a semi-mechanistic model of neutropenia, showing that the model can predict higher grades of toxicity. Next, we again validated the anticipatory toxicity models built on a semi-mechanistic basis using in-house preclinical data. Each of the two approaches presented here may be better suited for different situations. The empirical approach is better suited for toxicities with a poorly understood mechanistic basis, while the semi-mechanistic approach is well suited for neutropenia and other hematological toxicities. In either case, the anticipatory toxicity models were able to accurately predict the incidence of higher-grade toxicities in the given datasets. Thus, a careful analysis of these lower-grade toxicities may provide the opportunity to accelerate clinical development through the design of alternative clinical dose-escalation schemes. Such alternative escalation schemes may also be safer, as they focus on the forward prediction of the MTD before it is reached. Citation Format: Ekta Kadakia, Snehal Samant, Christopher J. Zopf, Dean Bottino, Greg Hather, Santhosh Palani, Wen Chyi Shyu, Arijit Chakravarty. Predicting Maximum Tolerated Dose during Phase I using anticipatory toxicity models. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3747. doi:10.1158/1538-7445.AM2014-3747

Empirical paths of poles to planes (eppps) constrain the kinematics of geological shear zones

Ductile shear zones are tabular bodies of deformed rocks bound by less deformed wall rocks. This work introduces a simple empirical approach to analysing the 3D kinematics of shear zones. The orientations of pre-shear planar markers distorted across natural shear zones by local strains are systematically measured and plotted as poles on lower hemisphere equal area projections that constrain smooth empiricalpaths ofpoles toplanes (eppps). Such eppps recording local strain gradients are used to fix a reference frame to the plane of greatest shear in any homogeneous bulk strain. Assuming that space can be taken as a proxy for time, the curvatures of pre-shear planar markers across shear zones are interpreted as the records of the 3D bulk strain histories of shear zones. The sig- or zig-moidal symmetries of sheared markers record different amounts of the same general strain within the same overall movement pattern (i.e. in a constant flow field) whatever its geometry or history. In effect eppps represent the strain memories of shear zones with successively inward readings recording successively younger shearing. In planes other than the bulk XY, great circle eppps indicate simple shear while hyperbolic eppps indicate pure shear. Eppps for suites of shear zones in Proterozoic gneisses in Sweden exhibit the parabolic shapes indicative of pure rather than simple shear.

Modelling transpiration, soil evaporation and yield prediction of soybean in North China Plain

The main objectives of this study were to assess and partition soybean evapotranspiration and modelling to predict yields. The SIMDualKc water balance model, that adopts the dual crop coefficient approach, was used to evaluate the transpiration and soil evaporation components. Transpiration estimates were then used with the Stewart's water-yield model to predict soybean yields. SIMDualKc was calibrated and validated using soil water observations relative to four crop seasons and six treatments. In addition, the adopted soil evaporation approach using the Ritchie's model was validated against microlysimeter observations, also for the four years of study. The calibrated Kcb was 1.05 for the mid-season and 0.35 at harvesting. Model results show a good agreement between available soil water data observed and predicted by the model, with root mean square errors of estimates (RMSE) smaller than 5% of the total available soil water. Testing the soil evaporation approach also produced good fitting results, with RMSE averaging 0.50mmd−1, hence confirming the appropriateness of the Ritchie's model to estimate soil evaporation of a cropped soil. The yield prediction through combining SIMDualKc and the Stewart's model was successful for all treatments, leading to a small RMSE of 381kgha−1 representing less than 11.5% of the maximum observed yield. These results indicate that yield may be predicted with that simple empirical approach provided that transpiration is accurately estimated and the water yield factor Ky is adequately calibrated. Consumptive water productivity WPET were high, ranging 0.95–1.46kgm−3, showing that both the crop variety and the agronomic practices may be extended in North China Plain.

Physical Model-Assisted Probability of Detection of Flaws in Titanium Forgings Using Ultrasonic Nondestructive Evaluation

Nondestructive evaluation is used widely in many engineering and industrial areas to detect defects or flaws such as cracks inside parts or structures during manufacturing or for products that need to be inspected while in service. The commonly used standard statistical model for such data is a simple empirical linear regression between the (possibly transformed) signal response variables and the (possibly transformed) explanatory variable(s) such as defect size. For some applications, such a simple empirical approach is inadequate. An important alternative approach is to use knowledge of the physics of the inspection process to provide information about the underlying relationship between the response and the explanatory variable or variables. Use of such knowledge can greatly increase the power and accuracy of the statistical analysis and enable, when needed, limited extrapolation outside the range of the observed explanatory variables. This article describes a set of physical model-assisted analyses to study the capability of two different ultrasonic testing inspection methods to detect synthetic hard alpha inclusion defects in titanium forging disks. Supplementary materials for this article are available online.

Cohort Replacement and Homeostasis in World Population, 1950–2100

Using a simple empirical approach, we analyze world and regional‐level cohort replacement as determined by the key components of population dynamics, i.e. fertility, survival, and migration, for 1950–2010, using UN data. We define two kinds of homeostatic relationships among these components: fertility responses to mortality change (type I) and migration responses to changes in net reproduction (type II), and show that both can be observed to some degree in this period. We examine the extent of cohort replacement embodied in the medium‐variant UN population projections over 2010–2100 and consider how the international migration assumptions made in such projections would be affected by a homeostatic perspective.

Evaluation of debris bed self-leveling behavior: A simple empirical approach and its validations

During a hypothetical core-disruptive accident (CDA) in a sodium-cooled fast reactor (SFR), degraded core materials can form roughly conically-shaped debris beds over the core-support structure and/or in the lower inlet plenum of the reactor vessel from rapid quenching and fragmentation of core material pool. However, coolant boiling may lead ultimately to leveling of the debris bed that is crucial to the relocation of molten core and heat-removal capability of debris bed. To clarify the mechanisms underlying this self-leveling behavior, several series of experiments were elaborately designed and conducted in recent years under the collaboration between Japan Atomic Energy Agency (JAEA) and Kyushu University (Japan). Based on the experimental observations and quantitative data obtained (mainly the time variation of bed inclination angle), a simple empirical approach to predict the self-leveling development depending on particle size, particle density and gas velocity was proposed. To confirm the rationality and wide applicability of this approach, over the past few years extensive efforts have been made by performing modeling investigations against a large number of experimental data covering various conditions, including difference in bubbling mode, bed geometry and range of experimental parameters. The present contribution synthesizes these efforts and gives detailed comparative analyses of the performed validations, thus, providing some insight for a better understanding of CDAs and improved verifications of computer models developed in advanced fast reactor safety analysis codes.

Secondary creep approximations of ice-rich soils and ice using transient relaxation tests

Abstract This paper serves two purposes: 1) it presents a simple empirical approach based on relaxation tests, from which secondary creep parameters can be approximated with significant practical time savings and 2) provides secondary creep observations and parameters for ice-rich soils as a function of cryostructure and massive ice facies. The form of test presented consists of a relaxation test in which the strain varies with time. Empirical evidence indicates that the onset of a secondary creep phase in ice-rich soils and ice is connected to the strain. Under increasing or decreasing stepped constant stress creep (CSC) tests, the initiation of secondary creep rates occurs very quickly upon a step change in the applied stress. The relaxation condition represents a continuously decreasing stepped creep tests. Once secondary creep conditions are initiated, the relaxation test can be used to approximate secondary creep. Secondary creep characteristics determined from relaxation tests agree well with CSC tests. Tests were conducted on ice-rich frozen silt from a Pleistocene age Yedoma permafrost composed of uniform windblown loess (Fairbanks silt). In addition to frozen soils, a number of samples of massive wedge ice and Matanuska glacial and basal ice were tested. Relaxation tests were conducted at temperature between − 1 °C and − 5 °C. Analysis of secondary creep parameters indicates that cryostructure has an influence on the secondary creep behavior of frozen soils. It is shown the volumetric unfrozen water has a significant impact on secondary creep parameters. With increasing unfrozen water content, parameters A and n approach the values observed for polycrystalline ice. It was shown for temperatures warmer than − 2 °C and stresses between 200 kPa and 1000 kPa, ice-rich soils creep at a faster rate than polycrystalline ice facies. This relates to unfrozen water. For temperatures colder than − 3 °C, the creep rates of polycrystalline ice are greater than undisturbed frozen soils for stresses less 200 kPa. The creep characteristics of remolded Fairbanks silt are not representative of undisturbed ice-rich samples and provide non-conservative creep estimates of undisturbed frozen soils.