Polynomial Correlation Research Articles

Total non-lewis structures: An application to predict the stability and reactivity of linear and angular polyacenes

In the present work, the total non-Lewis structure (TNLS) is introduced for describing the stability and reactivity of linear and angular polyacenes. TNLS of a molecule is derived from the natural bond orbital theory representing the antibonding orbitals and/or electron delocalization of π∗ orbitals. To verify this application, we obtained the TNLS values of thirteen linear and angular polyacenes and evaluated with other quantitative aromaticity probes based on reactivities, energetics, geometrics, and magnetic properties. Our results show that there is a remarkable second-order polynomial correlation between TNLS and seven popular global measures of aromaticity including hardness, resonance energy, aromatic stabilization energy, harmonic oscillator measure of aromaticity, magnetic susceptibility exaltation, global magnetic characteristics, and mean polarizability. By increasing the TNLS values of the systems the reactivity increases and stability decreases. It is worth mentioning that the angular polyacenes produce less TNLS values than the linear systems with the same number of benzene rings. Therefore, it can be stated that TNLS values confirmed with Clar’s rule which in general prove the angular polyacenes are more stable than linear ones.

Understanding the blending octane behaviour of unsaturated hydrocarbons: A case study of C4 molecules and comparison with toluene

Octane number (ON) is an important empirical parameter for developing and optimizing internal combustion engine (ICE) for knock resistance. Primary reference fuels (PRF) comprising iso-octane and n-heptane are the simplest gasoline surrogates. C4 hydrocarbons: butane isomers (n-butane and isobutane), butene isomers (1-butene, 2-butene and isobutene) and 1,3-butadiene are the smallest hydrocarbons with isomeric, saturated, unsaturated and conjugated bond structures, which makes them good candidates for understanding the blending octane behavior of saturated and unsaturated hydrocarbons. In this study, the blending octane behaviors of six PRF60 & C4 hydrocarbon mixtures were systematically investigated. A state-of-the-art kinetic models were used by merging the latest KAUST gasoline surrogate model with the AramcoMech 3.0 model. IDTs of stoichiometric fuel/air mixtures were simulated at wide range of pressure (20–50 atm) and temperature (600–1400 K). Three correlation equations were employed from the literature to predict the research octane number (RON) and motor octane number (MON) of all blends based on these calculated IDTs. Compared with the experimentally measured ON, the best correlation conditions and errors were identified. With the highest degree of unsaturation, 1,3-butadiene was found to be the strongest ON enhancer. Moreover, based on a polynomial correlation, a TPRF (PRF + toluene) blend was formulated by matching the RON and MON of PRF plus 1,3-butadiene blend, for a comparative analysis. Finally, the reactants’ consumption profile, flux and sensitivity analysis were simultaneously performed for explaining the chemistry behind the blending octane behavior of the PRF blends with 1,3-butadiene and toluene.

CFD Study for the Flow Behaviour of Nanofluid Flow over Flat Plate

Computation fluid dynamics (CFD) modelling of laminar heat transfer behaviour of three types of nanofluids over flat plate are studied. In the modelling the two dimensional under laminar model is used. The base fluid is pure water and the volume fraction of nanoparticles in the base fluid is 0, 1, 2, 3, and 4%. The applied Reynolds number range considered is 997.1 ≤ Re ≤ 9971. For modelling of the physical properties of the nanofluid, single phase approach is used. The effect of the volume fraction and the type of nanoparticles on the physical properties has been evaluated and presented. Then, the analysis the flow behaviour of these three nanofluids is conducted by presenting the effect of increasing the nanoparticles concentration on the velocity profile, wall shear stress, skin friction coefficient, and average heat transfer coefficient. The results show that the type of nanoparticles is an important parameter for the heat transfer enhancement as each type has shown dissimilar behaviour in this study. Moreover, a polynomial correlation has been obtained to present the relation of the wall shear stress, skin friction coefficient and average heat transfer coefficient as a function of the volume fraction for the three nanofluids.

Dietary inclusion effect of krill meal and various fish meal sources on growth performance, feed utilization, and plasma chemistry of grower walleye pollock (Gadus chalcogrammus, Pallas 1811)

A feeding trial was conducted to assess the effect of dietary inclusion of various aquatic animal protein sources on growth performance, feed utilization, body proximate composition, and plasma chemistry in grower walleye pollock (Gadus chalcogrammus, Pallas 1811). A total of 180 grower fish averaging 154.0 g in weight were chosen randomly and distributed into 12 flow-through tanks of 300 L (15 fish per tank). Four experimental diets were prepared in triplicate. Pollock meal (PM), anchovy meal (AM), krill meal (KM), and jack mackerel meal (JM) were used as the main protein source in the experimental diets, denoted PM, AM, KM, and JM diets, respectively. These diets were fed to fish twice a day at a satiation level for eight weeks. The weight gain and specific growth rate (SGR) of fish fed the KM and JM diets were higher than were those of fish fed the other diets. Daily feed intake (DFI) and daily protein intake (DPI) of fish fed the KM and JM diets were higher than were those of fish fed the PM and AM diets. The strong second polynomial correlation between the contents of 4 free amino acids (arginine, glutamic acid, histidine and leucine) in protein sources and WG, SGR, DFI and DPI were observed. The experimental diets had no effect on proximate composition of the muscle and liver. Plasma analysis did not differ between the experimental diets. In conclusion, KM and JM showed the greatest protein sources than among the ingredients assessed, and consequently KM and JM yielded the higher growth (WG and SGR) and feed intake (DFI and DPI).

An intelligent approach to predicting the effect of nanoparticle mixture ratio, concentration and temperature on thermal conductivity of hybrid nanofluids

Hybrid nanofluids are better heat transfer fluids than conventional nanofluids because of the combined properties of two or more nanoparticles. In this study, the thermal conductivity of Al2O3–ZnO nanoparticles suspended in a base fluid of distilled water is investigated. The experiments were conducted for three mixture ratios (1:2, 1:1 and 2:1) of Al2O3–ZnO nanofluid at five different volume concentrations of 0.33%, 0.67%, 1.0%, 1.33% and 1.67%. X-ray diffractometric analysis, X-ray fluorescence spectrometry and scanning electron microscopy were used to characterise the nanoparticles. The highest thermal conductivity enhancement achieved for Al2O3–ZnO hybrid nanofluids with 1:2, 1:1 and 2:1 (Al2O3:ZnO) mixture ratios was 36%, 35% and 40%, respectively, at volume concentration 1.67%. The study observed the highest thermal conductivity for Al2O3–ZnO nanofluid was achieved at a mixture ratio of 2:1. A “deeping” effect was observed at a mixture ratio of 1:1 representing the lowest value of thermal conductivity within the considered range. The study proposed and compared three models for obtaining the thermal conductivity of Al2O3–ZnO nanofluids based on temperature, volume concentration and nanoparticle mixture ratio. A polynomial correlation model, the adaptive neuro-fuzzy inference system model and an artificial neural network model optimised with three different learning algorithms. The adaptive neuro-fuzzy inference system model was most accurate in forecasting the thermal conductivity of the Al2O3–ZnO hybrid nanofluid with an R2 value of 0.9946.

Thermal Conductivity Modeling of Nanofluids Contain MgO Particles by Employing Different Approaches

The existence of solid-phase nanoparticles remarkably improves the thermal conductivity of the fluids. The enhancement in this property of the nanofluids is affected by different items such as the solid-phase volume fraction and dimensions, temperature, etc. In the current paper, three different mathematical models, including polynomial correlation, Multivariate Adaptive Regression Spline (MARS), and Group Method of Data Handling (GMDH), are applied to forecast the thermal conductivity of nanofluids containing MgO particles. The inputs of the model are the base fluid thermal conductivity, volume concentration, and average dimension of solid-phase, and nanofluids’ temperature. Comparing the proposed models revealed higher confidence of GMDH in estimating the thermal conductivity, which is attributed to its complicated structure and more appropriate consideration of the input’s interaction. The values of R-squared for the correlation, MARS, and GMDH are 0.9949, 0.9952, and 0.9991, respectively. In addition, based on the sensitivity analysis, the effect of thermal conductivity of the base fluid on the overall thermal conductivity of nanofluids is more remarkable compared with the other inputs such as volume fraction, temperature, and dimensions of the particles which are used as the inputs of the models.

Estimation of forest leaf area index and clumping index from the Global Positioning System (GPS) satellite carrier-to-noise-density ratio (C/N0)

ABSTRACTForest leaf area index (LAI) and clumping index (CI) are critical structural parameters to study the biomass, biogeochemical cycles, ecological simulation, and radiation transfer in a forest system. The ground-based measurements by traditional methods are costly, time-consuming, and are sensitive to variations in solar illumination conditions. Global Positioning System (GPS) satellites transfer L-band signals, and the presence of the forest canopy leads to an increase in noise. The GPS satellite’s signal strength is generally described by the carrier-to-noise-density ratio (C/N0). This study explores the potential of using the GPS satellite C/N0 to estimate forest canopy structural parameters. We performed experiments at 16 forest plots in northeastern China. LAI, CI, and canopy closure were estimated by digital hemispherical photography (DHP) using the CAN_EYE software. The GPS satellite C/N0 was recorded with a modified smartphone application, GPSTest. The relationship between the forest canopy structural parameters and satellite C/N0 was analyzed for those observations with satellite elevation angle (SEA) > 30°. The results show that both the true LAI and the effective LAI have strong linear and polynomial correlation with C/N0 and the coefficient of determination (R2) is larger than 0.7. CI is linearly related to C/N0(R2 = 0.56). The linear relationship between the canopy closure and C/N0 is much lower (R2= 0.28). Accounting for the SEA effect, LAI can be estimated with R2 > 0.8, and CI with R2 = 0.6. LAI and CI can be well estimated from C/N0 when the SEA effect is accounted for. In general, the GPS C/N0 provides an alternative method to estimate forest canopy structural parameters.

The Ponseti Method Decreased the Surgical Incidence in Children with Congenital Clubfoot: A Population-Based, 8 Birth-Year Cohort Study.

With the introduction of the Ponseti method for congenital clubfoot, the relapse rate and the surgical rate have been remarkably reduced. However, data from population studies for patients up to 10 years of age are still lacking. This study aimed to survey the relapse and surgery rates in the first 10 years of life in children with congenital clubfoot before and after introduction of the Ponseti method in Taiwan using the National Health Insurance Research Database (NHIRD). We retrieved clubfoot cases and related surgical procedures determined by International Classification of Diseases, Ninth Revision (ICD-9) 754.51 from the 1999-2016 NHIRD. Foot and ankle surgical procedures coded as ICD-9 754.51 for patients who were older than 6 months of age were regarded as surgical procedures for relapsed or residual deformities. The rate of clubfoot release when the patients were 0.5 to 1 year of age and extensive surgical procedures in the first 10 years of life were assessed among 8 birth-year cohorts (1999 to 2006) with a 10-year follow-up. Among 622 children with idiopathic congenital clubfoot diagnosis, 301 underwent a total of 367 surgical procedures for clubfoot between 6 months and 10 years of age. Disease incidence of 0.32 per 1,000 live births remained stable in the 8 birth-year cohorts. After the Ponseti method was introduced in 2002, there was a decrease in the clubfoot release rate in the 0.5 to 1-year age group (25.8% in the 1999 to 2002 birth-year cohorts compared with 17.6% in the 2003 to 2006 birth-year cohorts) and the rate of extensive surgical procedures (41.5% in the 1999 to 2002 birth-year cohorts compared with 31.3% in the 2003 to 2006 birth-year cohorts), both determined to be significant at p < 0.05 using the chi-square test. A significant decreasing trend (p < 0.05) was revealed in the rate of clubfoot release in patients who were 0.5 to 1 year of age by polynomial correlation, with an increasing negative slope after a turning point around 2002. The Ponseti method increased the ratio of minor to extensive surgical procedures when a surgical procedure was required. The Ponseti method decreased subsequent extensive surgical procedures for clubfoot, especially in the group that was 0.5 to 1 year of age. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Can the Image Processing Technique Be Potentially Used to Evaluate Quality of Frying Oil?

The objective of this study was to investigate the feasibility of a computer vision system (CVS) for assessing the contact angle of frying oil. The oil was used to fry carbohydrate- and protein-based foods for 40 h, and the oil was collected for measuring free fatty acids (FFA), peroxide value (PV), total polar materials (TPMs), and FOS reading (dielectric constant). The results showed that FFA linearly increased with frying time (R2 &gt; 0.95) while the polynomial correlation between TPMs and FOS reading as a result of time was observed (R2 &gt; 0.97). The contact angle obtained from CVS was highly correlated with all chemical qualities (R2 &gt; 0.94), except PV. In addition, the contact angle models could be used to adequately predict FFA, TPMs, and FOS reading of frying oil (R2 &gt; 0.91). This result suggested that the image processing technique through CVS could be an appropriate alternative to chemical analysis, especially for small- and medium-scale industrial frying.

Speech signal analysis as an alternative to spirometry in asthma diagnosis: investigating the linear and polynomial correlation coefficient

Speech production involves the vibration of the vocal cords. Voice changes will occur in respiratory diseases such as asthma due to the inflamed lung airways, which is part of the vocal tract. Spirometry is a well-known technique employed in diagnosis of asthma to give information on patient pulmonary function. The purpose of this research was to investigate the correlation between Forced Expiratory Volume to Forced Vital Capacity (FEV1/FVC) ratio obtained from spirometry and Harmonics-to-Noise Ratio (HNR) obtained from human speech, in order to determine whether speech analysis could be an alternative to spirometry in diagnosing asthma. Spirometry data was obtained from 150 subjects, who were asthmatic patients attending the Korle-Bu Teaching Hospital, Ghana. Speech data consisting of the vowel sounds /a:/,/e:/, /ɛ:/, /i:/,/o:/, /ɔ:/,/u:/ and phrase “She sells”, was also recorded from the subjects. 33 samples were selected and analyzed to generate speech parameters with Praat software. Correlation was established between HNR from the speech signals and spirometry data FEV1/FVC. The highest correlation coefficient was observed between HNR and vowel sound /ɛ:/ (42.08%). In conclusion, among the other speech vowels and phonemes, HNR of /ɛ:/ sound showed the most promise to being a suitable marker in using speech as an alternative to spirometry in asthma diagnosis.

Strong correlation between the laboratory dynamic CBR and the compaction characteristics of sandy soil

Construction of earth structures involves the use of compacted soils. In roads construction quality controls like the bearing capacity of the subgrade, base and subbase layers, CBR values and compaction characteristics are primarily important. In Sweden, it has become interesting to correlate new testing parameters collected by simple tests to the conventional compaction parameters collected from modified Proctor tests. This action will help in assessing the bearing capacity of the selected material simply and quickly using the recent developed techniques instead of the conventional techniques which have been considered as time consuming methods. The aim of this study is to demonstrate that the laboratory dynamic California bearing ratio (CBRLD) test can be used as a method of compaction assessment of selected subgrade soil. Moreover, it has been demonstrated in this study that the CBRLD can strongly be correlated to the compaction densities and molding water contents using polynomial correlation and a best-fit multiple regression model for a wide range of molding water contents. In addition, the repeatability of the dynamic laboratory CBR test was examined as discussed in the current article.

Correlating Rock-Eval™ Tmax with bitumen reflectance from organic petrology in the Bakken Formation

The Bakken Formation is a major unconventional shale play in North America, which lacks an independent calibration for accurately correlate thermal maturity from programmed pyrolysis (via temperature of maximum pyrolysis yield, Tmax) with optical methods (e.g., bitumen reflectance). In the present study, several samples from the upper and lower members of the Bakken Formation in North Dakota were analyzed by detailed organic petrography, bitumen reflectance, and Rock-Eval 6 pyrolysis. Organic petrography showed that the organic matter consists of various types of bitumen, amorphous matrix bituminite, liptodetrinite, acanthomorphic acritarch, marine alginite, granular micrinite, and inertinite macerals. Fluorescence color under UV light of macerals from the liptinite group was used to confirm the thermal maturity level. Due to the scarcity/absence of primary vitrinite, RO measurements on solid bitumen particles were converted to equivalent vitrinite reflectance (VRO-Eq) using a published correlation equation from the coeval New Albany Shale. Overall, geochemical analysis from Rock-Eval pyrolysis reveals almost similar trends for the upper and lower members, which allowed proposing a single correlation for VRO-Eq to Tmax for the Bakken Shale. Comparing the observed relationship for the Bakken Shale with the previously established models for the Devonian Duvernay Shale (Canada) and the Mississippian Barnett Shale (United States) shows discrepancies. Results confirmed the necessity of developing a specific equation for the Bakken Shale members to relate vitrinite and solid bitumen reflectance data to Tmax from Rock-Eval pyrolysis. Furthermore, the outcome of this study indicated that linear trends cannot accurately represent the relationship between these two parameters, considering the kerogen kinetics and non-linear relationship between transformation ratio (TR) and Tmax. Therefore, a polynomial correlation, a better fit to the data, was proposed to more accurately represent the nature of this relationship.

Relationships between the petrographic, physical and mechanical characteristics of sedimentary rocks in Jurassic weakly cemented strata

Physical and petrographic properties of sedimentary rocks have great influence on their mechanical behavior. Numerous laboratory tests were conducted on intact sandstones and mudstones obtained from Jurassic weakly cemented coal-bearing strata. Several physical and mechanical parameters, particularly the rock material constant mi and the brittleness coefficient BRIT−T, were determined. The microfabric of these sedimentary rocks was also analyzed to quantify their mineral compositions and to determine quantitative relationships among mineral compositions, physical and mechanical parameters using the regression analysis. Overall, both bulk density (ρ) and P-wave velocity (Vp) exhibit positive power relationships with uniaxial compressive strength (UCS) and Young’s modulus (E), respectively. The UCS of sandstones increases with increasing quartz content and decreasing feldspar content, and the brittleness of mudstones increases with the increase of quartz and feldspar contents. In addition, the rock material constant mi presents a logarithmic correlation with the ratio of feldspar-to-quartz content for sandstones and a polynomial correlation with the ratio of clay minerals to the quartz and feldspar contents for mudstones.

Temporal variability of soil water content and penetration resistance under different soil management practices

This study analyzed the temporal induced variability of soil penetration resistance (PR) and soil water content (SWC) of eight soil treatments, which ranged four tillage systems (conventional tillage [CT], reduced tillage [RT], no-tillage [NT], and fallow no-tillage [FNT]), to four soil management treatments (abandoned soil [that is, control], compacted soil, CT on compacted soil [tilled], and application of super absorbent polymers [SAP] on abandoned soil). The treatments were arranged in 20 × 4 m (65.6 × 13.1 ft) plots with four replicates. The temporal variability of soil PR and SWC was determined using four measurement repetitions over time, from 2014 to 2015 (December, February, April, and June). A total of 64 soil samples (four replications × eight treatments × two soil depth layers) were collected for the analysis of the temporal variations of SWC at four different times. According to the study, soil PR and SWC were influenced by soil management and tillage systems. Also, the study indicated that PR and SWC varied over time. For different treatments, a second degree polynomial correlation between PR and soil depth was observed during all measurement times. Tillage practice on compacted soils resulted in a decrease in PR during all measurement times and in both depths. In general, for most of the investigated soil treatments, a low variability of SWC between treatments was obtained at a given measurement time. It was discovered that the effect of soil management and soil depth was significant for SWC, but the interaction between depth and management was not statistically significant for any measurement time. The effect of soil treatment and soil depth, and the interaction between them, was significant for PR at p

A numerical study on slip correction factor of dust particle in HTGR

Abstract The movement of dust particle has important effects on the safe operation of HTGRs. Since most of the dust particle sizes in an HTGR are on the order of microns, the influence of the slip boundary on the particle movement needs to be considered. The present study uses computational fluid dynamics (CFD) models with a slip velocity to analyze the impacts of the velocity, pressure, temperature of helium and particle diameter on the slip correction factor in an HTGR. The results show that the slip correction factor is little affected by the flow velocity and it increases noticeably as the temperature increases, while it decreases when the pressure and diameter increase. The numerical simulation results are expressed as a simple polynomial correlation for 0.01

Nilsequences and multiple correlations along subsequences

The results of Bergelson, Host and Kra, and Leibman state that a multiple polynomial correlation sequence can be decomposed into a sum of a nilsequence (a sequence defined by evaluating a continuous function along an orbit in a nilsystem) and a null sequence (a sequence that goes to zero in density). We refine their results by proving that the null sequence goes to zero in density along polynomials evaluated at primes and along the Hardy sequence $(\lfloor n^{c}\rfloor )$. In contrast, given a rigid sequence, we construct an example of a correlation whose null sequence does not go to zero in density along that rigid sequence. As a corollary of a lemma in the proof, the formula for the pointwise ergodic average along polynomials of primes in a nilsystem is also obtained.

Exposure reducing remedies in cytotoxic drug preparation

Over the past decades, increasing attention has been paid to optimal design and operation of energy intensive industries. In this paper, a multi-hybrid model with high estimation capability has been applied for prediction of optimum consumed power. Consumed power is the most important factor for cascade refrigeration systems in which efficient estimation of this factor in various operating conditions is essential. The purpose of this paper is to present a new multi-hybrid Model in which six input variables consist of methane, ethane, propane, and nitrogen components composition along with suction and discharge pressures have been employed in order to estimate and predict the optimal consumed power. Having replaced by pure ethylene cycle in the olefin plant of the Tabriz Petrochemical Complex, the one and two stage-cascade cycles are modeled continuously by the proposed model. A hybrid group method of data handling (GMDH) along with linking between Aspen HYSYS and MATLAB software, optimized with Genetic algorithm (GA), is herein proposed to obtain efficient polynomial correlation to estimate optimal consumed power for these two cascade cycles. Results show that the proposed multi-hybrid model is superior to non-linear programming techniques for obtaining the optimum consumed power of cascade refrigeration cycles and finding the values of optimizing variables.

Computing the Composition of Ethanol-Water Mixtures Based on Experimental Density and Temperature Measurements

Two correlations were developed to calculate the composition of binary ethanol-water solutions from experimental temperature and density inputs. The first correlation is based on a Redlich-Kister (R-K) expansion and computes mixture composition within an average accuracy of ±0.45 wt.%. The R-K model is a non-linear function of composition and therefore requires the use of an iterative solving tool. A polynomial correlation was additionally developed which utilizes a direct solving method, and computes ethanol composition over a range of 0–100 wt.% [283.15–313.15 K] with an accuracy better than ±0.37 wt.%. The polynomial model is particularly advantageous as it can be tailored to specific composition ranges for increased accuracy. Both correlations are intended to provide a method for monitoring ethanol concentration within a chemical process in real time without off-line sample analysis, allowing for precise in-situ system control and optimization.

Characterization of the Fatty Acid Composition in Cultivated Atlantic Bluefin Tuna (Thunnus thynnus L.) Muscle by Gas Chromatography-Mass Spectrometry

A previously established gas chromatography-mass spectrometry method was applied for the determination of the fatty acid composition in the muscles of Atlantic bluefin tuna (Thunnus thynnus L). The fish were collected in the Mediterranean Sea and cultivated for several months. The goal of the study was to demonstrate the feasibility of these measurements and to improve knowledge about the influence of size and gender on the fatty acid composition. Although no significant differences were found with respect to gender, males and females showed different correlations of fatty acid composition with weight. In the males, a statistically significant linear correlation was found for 14:0, 16:0, 18:1n9, 20:1n9, 22:1n9 (positive correlation), and for 20:4n6, 20:5n3 22:6n3 (negative correlation). In the females, a statistically significant polynomial correlation for specific fatty acids was highlighted: specimens with medium size showed the lowest content of 20:1n9 and 22:1n9 and the highest content of 20:4n6, 20:5n3, and 22:6n3. Therefore, males smaller than 150 kg and females from 150 to 250 kg appeared to have the highest greater nutritional value. This study demonstrated the practicality of the analytical methodology and enhanced the knowledge of the influence of size on the fatty acid composition of Atlantic bluefin tuna muscle, reporting a newly established gender difference and representing a starting point to produce the best nutritional characteristics for farmed tuna.

Unsaturated Shear Strength of a Sri Lankan Residual Soil from a Landslide-Prone Slope and its Relationship with Soil–Water Retention Curve

Unsaturated soil mechanics has become a topic of interest among the Sri Lankan geotechnical community owing to its importance in different applications, especially slope stability. In this study, soil samples collected from a landslide area in Sri Lanka were subjected to soil–water retention curve (SWRC) tests and suction-monitored direct shear tests. SWRC tests were conducted on both undisturbed and statically compacted samples and the results were modelled using Van Genutchen equation. The compacted samples having the same dry density as the undisturbed block samples exhibited a similar SWRC. Consolidated drained direct shear tests and suction-monitored direct shear tests were conducted on compacted samples to determine saturated and unsaturated shear strength respectively. The unsaturated shear strength followed a non-linear envelope with respect to matric suction, as shown by a good correlation for the cases of second-order polynomial correlation (R2 = 0.970) and the prediction using Vanapalli et al. model and SWRC with K = 1.2 (R2 = 0.941). These test results confirm the validity of using SWRC for predicting unsaturated shear strength of a compacted Sri Lankan silty sand.