Empirical Predictive Relationships Research Articles

Fundamental Structure–Function Relationships in Vegetable Oil-Based Lubricants: A Critical Review

Vegetable oil (VO)-based lubricants are environmentally friendly replacements for mineral oils. This work critically reviews the literature and identifies the molecular structures in VO-based lubricants which have been used to improve performance. The specific roles that size, type, number, position, spatial arrangement, and symmetry play in determining lubricating functionality were highlighted. Data were systematically collected to identify the contributions of major structural components and relate them to specific physical functionality measurables. The relationships were presented to reveal structure–function trends. Empirical predictive relationships between flow and thermal transition properties and structures were established. Molecular mass was revealed to be a fundamental determinant of viscosity and transition temperatures, but these properties were shown to also be influenced by other structural factors such as polar functional groups, branching, and symmetry. Almost all the examined viscosity data plotted versus molecular mass are enclosed within the 95% prediction band of an exponential rise to a maximum function (R2 = 0.7897). Generally, for both flow and thermal transition, a given structure versus function follows simple linear or exponential functions with unbranched VO-based lubricants, lending themselves more easily to strong correlations. This review is a first step towards comprehensively relating structure to lubrication function. The revealed relationships of structural contributions to the lubricating functionality of VO-based lubricants provide insights that may be used to extend the ranges of chemical and physical properties of some molecular architectures examined.

Empirical relationships for estimating the crest settlement of earth-core rockfill dams subjected to earthquakes

In this study, new empirical predictive relationships for earthquake-induced crest settlement of earth-core rockfill dams (ECRDs) were developed. A case history database of 19 dams that had been subjected to earthquakes was utilized. The presented relationships correlate the intensity measure (IM) of the earthquake records with the observed settlements, and thus, employing IMs that appropriately describe the severity of ground motion is of vital importance. It is well known that the dynamic properties of an ECRD can change significantly depending on the severity of an earthquake, and that this phenomenon can substantially impact the dynamic responses of dams. Accordingly, two IMs were suggested, taking into account the essential characteristics of ground motions affecting the nonlinear behaviour of ECRDs. The results indicate that the proposed relationships effectively address the limitations of the existing ones, and that they are practical tools that efficiently predict the seismic settlements of ECRDs.

Empirical Relationships for Prediction of Mechanical Properties of High-Strength Concrete

Empirical Relationships for Prediction of Mechanical Properties of High-Strength Concrete

Predicting the Effect of Relaxation on Interfacial Area Development in Multiphase Flow

AbstractA variety of two‐phase flow experiments, currently available in the literature, are compared to study the effect of fluid relaxation on interfacial area generation. Interfacial area is an important parameter that controls mass transfer in many engineered multiphase systems, so it is important to develop accurate predictive tools describing multiphase flow to engineer efficient processes. An empirical predictive relationship was developed describing a specific interfacial area‐wetting saturation relationship that depends on the number of quasi‐equilibrium relaxation points obtained during a drainage or imbibition experiment. The empirical expression was tested and verified using a number of existing datasets. We found that different relationships were needed depending on the fluid properties as well as the porous medium. However, clear trends were observed that can, once a predictive relationship is established for the system, allow us to design multiphase flow systems to produce a desired amount of interfacial area tailored to a particular application.

Development of Empirical Relationships for Prediction of Mechanical and Wear Behavior of Copper Matrix Surface Composite by Friction Stir Processing Technique

Development of Empirical Relationships for Prediction of Mechanical and Wear Behavior of Copper Matrix Surface Composite by Friction Stir Processing Technique

Storm Waves at the Shoreline: When and Where Are Infragravity Waves Important?

Infragravity waves (frequency, f = 0.005–0.05 Hz) are known to dominate hydrodynamic and sediment transport processes close to the shoreline on low-sloping sandy beaches, especially when incident waves are large. However, in storm wave conditions, how their importance varies on different beach types, and with different mixes of swell and wind-waves is largely unknown. Here, a new dataset, comprising shoreline video observations from five contrasting sites (one low-sloping sandy beach, two steep gravel beaches, and two compound/mixed sand and gravel beaches), under storm wave conditions (deep water wave height, H0 up to 6.6 m, and peak period, Tp up to 18.2 s), was used to assess: how the importance and dominance of infragravity waves varies at the shoreline? In this previously unstudied combination of wave and morphological conditions, significant infragravity swash heights (Sig) at the shoreline in excess of 0.5 m were consistently observed on all five contrasting beaches. The largest infragravity swash heights were observed on a steep gravel beach, followed by the low-sloping sandy beach, and lowest on the compound/mixed sites. Due to contrasting short wave breaking and dissipation processes, infragravity frequencies were observed to be most dominant over gravity frequencies on the low-sloping sandy beach, occasionally dominant on the gravel beaches, and rarely dominant on the compound/mixed beaches. Existing empirical predictive relationships were shown to parameterize Sig skillfully on the sand and gravel beaches separately. Deep water wave power was found to accurately predict Sig on both the sand and gravel beaches, demonstrating that, under storm wave conditions, the wave heights and periods are the main drivers of infragravity oscillations at the shoreline, with the beach morphology playing a secondary role. The exception to this was the compound/mixed beach sites where shoreline infragravity energy remained low.

Empirical predictive relationships for rigid sliding displacement based on directionally-dependent ground motion parameters

The seismic performance of earth slopes is typically quantified by the predicted rigid-sliding-block displacement of a simplified sliding mass. Current empirical predictive relationships for earthquake-induced sliding displacements of slopes are generally developed based on the computed displacement data from a suite of earthquake ground motion time histories. The displacement predicted from these relationships is for the ground motion intensity measures associated with a specific ground motion time history. These intensity measures are different from those for a single definition of bidirectional ground motion that are used in ground motion prediction equations and the distribution of ground shaking following an earthquake (e.g., ShakeMap), which take into consideration ground motion directionality. Therefore, the use of ground motion intensity measures is not consistent throughout the assessment process of seismic sliding displacement of slopes. This paper presents rigid sliding displacements calculated for a set of ground motion records by rotating the horizontal components through all angles. The degree of the azimuthal variation of sliding displacement of slopes with different yield accelerations is examined by analyzing the distribution of sliding displacements in all orientations. Empirical predictive relationships for the orientation-independent earthquake-induced sliding displacement of slopes are developed as a function of directionally-dependent definitions of ground motion parameters. The proposed relationships ensure consistency between the derivation of the ground motion intensity measures and its application in the prediction of sliding displacement of slopes, and consider the potential effects of ground motion directionality on displacement predictions.

Empirical models for the prediction of ground motion duration for intraplate earthquakes

Many empirical relationships for the earthquake ground motion duration were developed for interplate region, whereas only a very limited number of empirical relationships exist for intraplate region. Also, the existing relationships were developed based mostly on the scaled recorded interplate earthquakes to represent intraplate earthquakes. To the author's knowledge, none of the existing relationships for the intraplate regions were developed using only the data from intraplate regions. Therefore, an attempt is made in this study to develop empirical predictive relationships of earthquake ground motion duration (i.e., significant and bracketed) with earthquake magnitude, hypocentral distance, and site conditions (i.e., rock and soil sites) using the data compiled from intraplate regions of Canada, Australia, Peninsular India, and the central and southern parts of the USA. The compiled earthquake ground motion data consists of 600 records with moment magnitudes ranging from 3.0 to 6.5 and hypocentral distances ranging from 4 to 1000 km. The non-linear mixed-effect (NLMEs) and logistic regression techniques (to account for zero duration) were used to fit predictive models to the duration data. The bracketed duration was found to be decreased with an increase in the hypocentral distance and increased with an increase in the magnitude of the earthquake. The significant duration was found to be increased with the increase in the magnitude and hypocentral distance of the earthquake. Both significant and bracketed durations were predicted higher in rock sites than in soil sites. The predictive relationships developed herein are compared with the existing relationships for interplate and intraplate regions. The developed relationship for bracketed duration predicts lower durations for rock and soil sites. However, the developed relationship for a significant duration predicts lower durations up to a certain distance and thereafter predicts higher durations compared to the existing relationships.

Development of empirical relationships for prediction of mechanical and wear properties of AA6082 aluminum matrix composites produced using friction stir processing

Friction Stir Processing (FSP) has been established as a potential solid state production method to prepare aluminum matrix composites (AMCs). FSP was effectively applied to produce AA6082 AMCs reinforced with various ceramic particles such as SiC, Al2O3, TiC, B4C and WC in this work. Empirical relationships were estimated to predict the influence of FSP process parameters on the properties such as area of stir zone, microhardness and wear rate of AMCs. FSP experiments were executed using a central composite rotatable design consisting of four factors and five levels. The FSP parameters analyzed were tool rotational speed, traverse speed, groove width and type of ceramic particle. The effect of those parameters on the properties of AMCs was deduced using the developed empirical relationships. The predicted trends were explained with the aid of observed macro and microstructures.

Empirical predictive relationship for seismic lateral displacement of slopes

The objective of this study is to develop an empirical predictive relationship for permanent lateral displacements for use in assessing the seismic stability of slopes, earthen dams and/or embankments subject to stable continental earthquake motions. The empirical relationship is developed from 620 horizontal motions for stable continental regions, consisting of 28 recorded motions and 592 scaled motions. For each motion, the permanent relative displacements are computed using the Newmark sliding block procedure for a suite of yield accelerations. The proposed predictive relationship is derived by performing separate regression analyses for each yield acceleration. This allows the relationship to be simply formulated in terms of ground motion characteristic parameters, independent of yield acceleration, and results in lower standard deviations than those for relations developed by regressing all the data in a single analysis. The non-linear mixed-effects technique is used to regress the data as functions of maximum ground accelerations and velocities. To account for the zero displacement data, logistic regression was conducted to model the probability of zero-displacement occurrences. Then, the probability models were applied as weighting functions to the non-linear mixed-effects regression results. Also, a similar relationship for active shallow crustal motions is developed and compared with the stable continental region relationship. Lastly, the predicted displacements from the proposed model are shown to be in good agreement with those computed using motions recorded during the Mineral, Virginia earthquake of 23 August 2011.

An empirical significant duration relationship for stable continental regions

An empirical predictive relationship correlating significant duration to earthquake magnitude, site-to-source distance, and local site conditions (i.e., rock vs. stiff soil) for stable continental regions is presented herein. The correlations were developed from data derived from 620 horizontal motions for stable continental regions (e.g., central and eastern North America: CENA), consisting of 28 recorded motions and 592 scaled motions. The data set encompasses the earthquake magnitude from 4.5 to 7.6 and the distance from 0.1 to 199 km. The non-linear mixed-effects regression technique was used to fit a predictive model to the significant duration data. Similar to the trend observed from active shallow crustal region motions, significant durations predicted for stable continental region motions increased with increasing earthquake magnitude and increasing site-to-source distance. In comparing the predicted durations for CENA motions with those for motions from active shallow crustal regions (e.g., western North America: WNA), it is shown that the differences in significant durations for the two regions are relatively minor for site-to-source distances less than about 100 km. Lastly, the significant durations predicted by the proposed model are shown to be in good agreement with durations of the motions recorded during the Mineral, Virginia earthquake of August 23, 2011.

Improving seismotectonics and seismic hazard assessment along the San Ramón Fault at the eastern border of Santiago city, Chile

The San Ramón Fault is an active west-vergent thrust fault system located along the eastern border of the city of Santiago, at the foot of the main Andes Cordillera. This is a kilometric crustal-scale structure recently recognized that represents a potential source for geological hazards. In this work, we provide new seismological evidences and strong ground-motion modeling from hypothetic kinematic rupture scenarios, to improve seismic hazard assessment in the Metropolitan area of Central Chile. Firstly, we focused on the study of crustal seismicity that we relate to brittle deformation associated with different seismogenic fringes in the main Andes in front of Santiago. We used a classical hypocentral location technique with an improved 1D crustal velocity model, to relocate crustal seismicity recorded between 2000 and 2011 by the National Seismological Service, University of Chile. This analysis includes waveform modeling of seismic events from local broadband stations deployed in the main Andean range, such as San José de Maipo, El Yeso, Las Melosas and Farellones. We selected events located near the stations, whose hypocenters were localized under the recording sites, with angles of incidence at the receiver <5° and S–P travel times <2 s. Our results evidence that seismic activity clustered around 10 km depth under San José de Maipo and Farellones stations. Because of their identical waveforms, such events are interpreted like repeating earthquakes or multiplets and therefore providing first evidence for seismic tectonic activity consistent with the crustal-scale structural model proposed for the San Ramón Fault system in the area (Armijo et al. in Tectonics 29(2):TC2007, 2010). We also analyzed the ground-motion variability generated by an M w 6.9 earthquake rupture scenario by using a kinematic fractal k −2 composite source model. The main goal was to model broadband strong ground motion in the near-fault region and to analyze the variability of ground-motion parameters computed at various receivers. Several kinematic rupture scenarios were computed by changing physical source parameters. The study focused on statistical analysis of horizontal peak ground acceleration (PGAH) and ground velocity (PGVH). We compared the numerically predicted ground-motion parameters with empirical ground-motion predictive relationships from Kanno et al. (Bull Seismol Soc Am 96:879–897, 2006). In general, the synthetic PGAH and PGVH are in good agreement with the ones empirically predicted at various source distances. However, the mean PGAH at intermediate and large distances attenuates faster than the empirical mean curve. The largest mean values for both, PGAH and PGVH, were observed near the SW corner within the area of the fault plane projected to the surface, which coincides rather well with published hanging-wall effects suggesting that ground motions are amplified there.

An empirical bracketed duration relation for stable continental regions of North America

An empirical predictive relationship correlating bracketed duration to earthquake magnitude, site-to-source distance, and local site conditions (i.e. rock vs. stiff soil) for stable continental regions of North America is presented herein. The correlation was developed from data from 620 horizontal motions for central and eastern North America (CENA), consisting of 28 recorded motions and 592 scaled motions. The bracketed duration data was comprised of nonzero and zero durations. The non-linear mixed-effects regression technique was used to fit a predictive model to the nonzero duration data. To account for the zero duration data, logistic regression was conducted to model the probability of zero duration occurrences. Then, the probability models were applied as weighting functions to the NLME regression results. Comparing the bracketed durations for CENA motions with those from active shallow crustal regions (e.g. western North America: WNA), the motions in CENA have longer bracketed durations than those in the WNA. Especially for larger magnitudes at far distances, the bracketed durations in CENA tend to be significantly longer than those in WNA.

Sequestration of Alkyltin(IV) Compounds in Aqueous Solution: Formation, Stability, and Empirical Relationships for the Binding of Dimethyltin(IV) Cation by N‐ and O‐Donor Ligands

The sequestering ability of polyamines and aminoacids of biological and environmental relevance (namely, ethylenediamine, putrescine, spermine, a polyallylamine, a branched polyethyleneimine, aspartate, glycinate, lysinate) toward dimethyltin(IV) cation was evaluated. The stability of various dimethyltin(IV) / ligand species was determined in NaClaq at t = 25°C and at different ionic strengths (0.1 ≤ I/mol L−1 ≤ 1.0), and the dependence of stability constants on this parameter was modeled by an Extended Debye-Hückel equation and by Specific ion Interaction Theory (SIT) approach. At I = 0.1 mol L−1, for the ML species we have log K = 10.8, 14.2, 12.0, 14.7, 11.9, 7.7, 13.7, and 8.0 for ethylenediamine, putrescine, polyallylamine, spermine, polyethyleneimine, glycinate, lysinate, and aspartate, respectively. The sequestering ability toward dimethyltin(IV) cation was defined by calculating the parameter pL50 (the total ligand concentration, as −log CL, able to bind 50% of metal cation), able to give an objective representation of this ability. Equations were formulated to model the dependence of pL50 on different variables, such as ionic strength and pH, and other empirical predictive relationships were also found.

Speciation of Phytate Ion in Aqueous Solution. Thermodynamic Parameters for Zinc(II) Sequestration at Different Ionic Strengths and Temperatures

Results of an investigation on phytate interactions with zinc(II) cation in NaNO3aq at different ionic strengths (0.1≤I/mol⋅L−1≤1.0) are reported. Stability constants of various Zn i H j Phy(12−2i−j)− species were determined by potentiometry (ISE-H+ glass electrode) and the corresponding formation enthalpies by direct calorimetric titrations. Data obtained were used to provide an exhaustive speciation scheme of zinc(II) in the presence of phytate, as well as a comprehensive representation of the binding ability of phytate toward zinc(II) in different conditions. Different pL50 values [an empirical parameter already proposed, expressed as the −log 10 C Phy, where C Phy is the total phytate concentration necessary to bind 50% zinc(II)] were calculated in several conditions, and equations were formulated to model its dependence on different variables, such as ionic strength, temperature and pH. Other empirical predictive relationships are also proposed.

Interaction of methyltin(IV) compounds with carboxylate ligands. Part 2: formation thermodynamic parameters, predictive relationships and sequestering ability

AbstractThermodynamic data of mono‐, di‐ and tri‐methyltin(IV)‐carboxylate complexes (acetate, malonate, succinate, oxydiacetate, diethylenetrioxydiacetate, malate, citrate, 1,2,3‐tricarballylate, 1,2,3,4‐butanetetracarboxylate, 1,2,3,4,5,6‐benzenehexacarboxylate) in aqueous solution are reported at t = 25 °C and I = 0 mol l−1. Thermodynamic parameters obtained were analysed to formulate empirical predictive relationships as a function of different parameters, such as the number of carboxylate groups of the ligand and the charge of the alkyltin(IV) cation. Sequestration diagrams of citrate and 1,2,3‐tricarballylate towards alkyltin(IV) cations at different pH values are also reported and discussed. Copyright © 2007 John Wiley &amp; Sons, Ltd.

Transverse dispersion of non-reactive tracers in porous media: A new nonlinear relationship to predict dispersion coefficients

Assessing the potential of natural attenuation in groundwater relies on the ability to predict and quantify the processes that occur in contaminant plumes. Transverse dispersion is a significant mass transfer mechanism for mixing of electron acceptors and donors and thus may control the lengths of steady state plumes. Laboratory experiments were carried out using a 2-dimensional acrylic glass tank filled with glass beads, quartz sand and field site material as porous media. Flow velocities and grain sizes were varied in order to cover a large range of Peclet numbers including typical field scenarios. The laboratory study was extended by a comprehensive literature search to compare the new results with earlier work. As a result we propose a new empirical relationship for prediction of transverse dispersion coefficients ( D t) which is based on the Peclet number ( Pe). This new relationship indicates a nonlinear dependency on the flow velocity ( ν a) and grain size ( d), namely a relative decrease of the dispersion coefficient with increasing flow velocity in relatively fast flowing water: D t / D aq = D p / D aq + 0.28( Pe) 0.72 (with Pe = ν a d / D aq; D aq and D p denote the aqueous and pore diffusion coefficients, resp.).

Ground motion scaling in the Marmara region, Turkey

SUMMARY Predictive relationships for the ground motion in the Marmara region (northwestern Turkey) are parametrized after regressing three-component waveforms from regional earthquakes, in the frequency range: 0.4‐15.0 Hz, and in the distance range: 10‐200 km. The data set consists of 2400 three-component recordings from 462 earthquakes, recorded at 53 stations. Moment magnitudes, M w, range between 2.5 and 7.2. The largest event for which we have waveforms available (M w 7.2) occurred in Duzce on 1999 November 12. The aftershocks of that earthquake, together with the aftershocks of the 1999 August 17 Izmit event (M w = 7.4), are included in the dataset. Regressions are performed, independently, on Fourier velocity spectra and on peak ground velocities, for a large number of sampling frequencies. A simple model is used to relate the logarithm of the measured ground motion to excitation, site, and propagation terms. Results obtained for peak velocities are used to define a piecewise continuous geometrical spreading function, g(r), a frequency-dependent Q(f ), and a distance-dependent duration function. The latter is used, through random vibration theory (RVT), in order to predict time-domain characteristics (i.e. peak values) of the ground motion. The complete model obtained for the peak ground motion was used to match the results of the regressions on the Fourier amplitudes. Fourier velocity spectra for the combined horizontal motion are best fit by a hinged quadrilinear geometrical spreading function for observations in the 10‐200 km hypocentral distance ranges as a function of frequency: f 100, f ≥ 1.0 Hz, r −1.0 for r ≤ 30 km; r −0.6 for 30 100 km. The frequency-dependent crustal shearwave quality factor Q (f ) coefficient Q( f ) = 180 f 0.45 . The T (5‐75 per cent) duration window provides good agreement between observed and predicted peak values. By modelling the behaviour of the small earthquakes at high frequency, we also quantified a regional parameter κ = 0.055 s. Spectral models with one single-corner frequency (Brune), and with two-corner frequencies (Atkinson and Silva) fit the observed high-frequency excitation levels equally well, whereas the model by Atkinson and Silva fits the low-frequency observations slightly better than Brune’s. RVT is used to predict the absolute levels of ground shaking, following Boore’s implementation of the stochastic ground motion model (Boore’s SMSIM codes). Our regional empirical predictive relationships are compared to the ones adopted in several regions of the world, from California to Western United States.

Speciation of Phytate Ion in Aqueous Solution. Sequestering Ability toward Mercury(II) Cation in NaClaq at Different Ionic Strengths

As a contribution to understanding the speciation of mercury in the environment and to the study of the sequestering ability of phytate (Phy) toward heavy metal and organometal cations, this paper describes the results of an investigation (at t = 25 degrees C by potentiometry, ISE-H+ glass electrode) of its interactions with mercury(II) cation in NaCl aqueous solutions at different ionic strengths (I = 0.15 and 1.0 mol L(-1)), in the pH range 2.5 < or = pH < or = 9.5 and considering metal-to-ligand ratios of 1:1 < or = Hg/Phy < or = 4:1. The formation of 11 HgiHjPhy(12-2i-j)(- species with i = 1 and 0 < or = j < or = 7 and i = 2 and 0 < or = j < or = 2 was observed. Their complex formation constant values proved to be fairly dependent on ionic strength. The speciation of phytic acid and mercury(II) is also dependent on the metal-to-ligand ratio; the dependence of the stability of phytate-mercury(II) species on the phytate protonation step was modeled, and an empirical predictive relationship was proposed. From the results obtained, phytate has very good sequestering ability toward Hg2+, even in the presence of considerable excesses of chloride ion, that is, another ligand strongly interacting with mercury; this supports future studies both on the use of plants that naturally synthesize it for phytoremediation purposes and on its direct application in remediation techniques.

Improving empirical relationships for predicting the effect of vegetation change on annual water yield

Continuing worldwide growth in results from paired-catchment vegetation-change experiments raises the possibility of improving empirical predictions of change in annual water yield. However, the results are variable, and a large amount of variation in change in annual yield is not explained by relationships derived from the results. We investigated causes of this unexplained variation (scatter), for relationships between change in annual yield and precipitation, and proposed procedures for improving the strength and accuracy of the relationships. Results from 35 New Zealand experiments were used to investigate three possible causes of the scatter: inter-annual variability of precipitation, heterogeneity arising from combining increases and decreases in annual yield, and heterogeneity from mixing different forms of reported change in annual yield. We also investigated the significance of data gaps (uneven distribution of results across the full range of precipitation values). Inter-annual variability of precipitation was the most important of the causes of scatter investigated. Scatter was reduced (44% increase in R 2) by relating maximum change in annual yield to the annual precipitation for the year of the maximum, rather than to mean annual precipitation. Small sample size was found to be a more serious problem in the development of predictive relationships than heterogeneity of change in annual yield data; however, the accuracy of prediction can be increased by homogenisation of the change in annual yield data using transformation equations. We also found that data gaps can decrease the accuracy of the predictive relationships, but, in general, have no effect on the amount of variation explained. Our main conclusion was that annual precipitation in the year of maximum change in annual yield should be included as an explanatory variable in empirical predictive relationships. We also recommend that, before developing relationships, basic data from all experiments be re-analysed using a consistent methodology.