Correction Factor Equation Research Articles

Applicability of CMOD to Obtain the Actual Fracture Toughness of Rightly-Cracked Fibrous Concrete Beams

Unfortunately, most of the previous work studying the fracture toughness of fibrous composites has deliberately ignored bridging the fiber onto the pre-crack/notch surfaces by creating such a crack as a through-thickness crack (TTC). Furthermore, no standard specifications for measuring the fracture toughness of fibrous composites have considered the fiber bridging through the pre-notch. Only a few pieces of research, no more than fingers on one hand, have addressed this problem by creating an actual crack, i.e., a matrix crack (MC) instead of a TTC. The challenge these researchers face is the inability to calculate the fracture toughness directly through the stress intensity factor (SIF) relationship because there is no geometry correction factor equation, f(a/d), for an MC. The main objective of the present work is to calculate f(a/d) and ascertain a relationship between the SIF and crack mouth opening displacement (CMOD) for an MC numerically using 3-D finite element analysis. An experimental program was also conducted to measure the fracture toughness of three types of concrete beams: high-strength concrete (HSC) beams with a TTC, HSC beams with an MC, and fiber-reinforced concrete (FRC) beams with an MC. The results showed that FRC beams with an MC have the highest fracture toughness and, subsequently, the highest resistance to crack growth. The numerical results revealed a suggested relationship between the SIF and CMOD of FRC beams with an MC. This relation was used to predict the fracture toughness of FRC with an MC by the critical value of CMOD measured experimentally.

An extended kinetic model-based correction factor equation to account hemodialysis post-treatment hemoconcentration.

The hemoconcentration effect for middle weight solutes in hemodialysis is corrected by oversimplified methods based on hematocrit changes or distribution volume variations. Here we implemented a variable volume dual pool kinetic model targeted at obtaining a precise correction factor equation for extracellularly distributed solutes based on relevant kinetic parameters such as the ultrafiltration to dry weight ratio UF/DW, the dialyzer clearance, Kd, the intercompartment mass-transfer coefficient, Kc, and the central compartment to extracellular volume ratio, α. More than 300,000 solutions of the model were computed, performing a sweep among physiological values of the proposed kinetic parameters, resulting in a linear regression denoted by the expression fcorr = 1.0707 - 5.2246 (UF/DW) - 0.0005 Kd - 0.0004 Kc - 0.0007 α, with an excellent coefficient of determination R2 = 0.983. The presented fcorr provides a substantial extension of the currently implemented methods to estimate the hemoconcentration factor for middle and high molecular weight extracellular distributed solutes in hemodialysis.

The Effect of Coatings on Cutting Force in Turning of C45 Steel.

This article focuses on the development of a mathematical model of a cutting force that is applicable for coated and uncoated cutting tool inserts and aims to enable more accurate calculation of the cutting force. Two common PVD coatings, AlTiN and TiAlCrN, were used. Firstly, a mathematical model of the cutting force based on the specific cutting force and cutting area is proposed. This mathematical model considers the cutting speed and coating correction factor as well as the real cutting edge geometry, i.e., it includes both the straight and rounded parts of the cutting edge. For this proposed model, material constants for C45 steel, which was machined with uncoated inserts, were obtained. Before determining an equation for a coating correction factor and implementing it into the model, experimental cutting force data for coated and uncoated inserts were compared using a paired t-test. The result was that the difference between them was statistically significant. Their percentage difference was found to be up to 4%. The correction factor equation that was obtained and implemented into the mathematical model was applied to compare the calculated and experimental data of the coated inserts, also using a paired t-test. The result was that the difference between them was insignificant. Moreover, their percentage difference was found to be up to 0.6%.

Seeking Nonspecific Binding: Assessing the Reliability of Tissue Dilutions for Calculating Fraction Unbound.

It has become commonplace (270+ article citations to date) to measure the fraction unbound (FrUn) of drugs in tissue homogenates and diluted plasma and then use a Correction Factor Equation (CFE) to extrapolate to the undiluted state. The CFE is based on assumptions of nonspecific binding with experimental use of very low drug concentrations. There are several possible determinants of apparent nonspecific binding as measured by methods such as equilibrium dialysis: true macromolecule binding and lipid partitioning along with receptor, enzyme, and transporter interactions. Theoretical calculations based on nonlinear protein binding indicate that the CFE will be most reliable to obtain FrUn when added drug concentration is small, binding constants are weak, protein concentrations are relatively high, and tissue dilution is minimal. When lipid partitioning is the sole factor determining apparent tissue binding, the CFE should be perfectly accurate. Use of very low drug concentrations, however, makes it more likely that specific binding to receptors and other targets may occur, and thus FrUn may reflect some binding to such components. Inclusion of trapped blood can clearly cause minor to marked discrepancies from purely tissue binding alone, which can be corrected. Furthermore, assessment of the occurrence of ionization/pH shifts, drug instability, and tissue metabolism may be necessary. Caution is needed in the use and interpretation of results from tissue dilution studies and other assessments of nonspecific binding, particularly for very strongly bound drugs with very small FrUn values and in tissues with metabolic enzymes, receptors, and trapped blood. SIGNIFICANCE STATEMENT: The use of tissue, plasma, and cell preparations to help obtain fraction unbound and tissue-to-plasma partition coefficients in pharmacokinetics has grown commonplace, especially for brain. This report examines theoretical, physiological, and experimental issues that need consideration before trusting such measurements and calculations.

X-ray Fluorescence Analysis of Antimony Content in Extruded Polyethylene Terephthalate Food Packaging Below the Infinite Thickness

Consumer and environmental groups have increasing concern about heavy metal contaminants and residual catalysts in plastics inducing negative human and environmental impacts. Regulations of heavy metals in food-contact plastics seek to reduce these risks by establishing maximum allowable threshold levels. However, traditional quantification methods of heavy metal concentrations, e.g., inductively coupled plasma (ICP) and atomic absorption spectroscopy, are time-consuming and expensive. X-ray fluorescence (XRF) techniques provide a rapid, non-destructive method for monitoring heavy metals, but the sample must be of sufficient thickness for accurate XRF analysis. This study developed a correction factor equation enabling rapid, accurate XRF measurements of antimony concentration in thin plastic samples at thicknesses common for food packaging applications by measuring XRF concentration as a function of thickness and establishing correlations with the measured ICP concentration. This correction factor approach yielded antimony concentrations from XRF measurements for 94% of the challenge samples tested within the acceptability metric stated in EPA Method 6200. The approach described herein enables rapid, cost-effective screening and regulatory compliance for safety and environmental impact benefiting consumers, manufacturers, and the environment.

Derivation of Complete Stress–Strain Curve for SSTT-Confined High-Strength Concrete in Compression

Abstract For concrete structural behavior analysis, the complete axial stress–strain curves in compression can be determined by using a closed-loop servo-controlled hydraulic testing machine. The applied loading as well as the axial deformation reading of the loaded concrete specimen is recorded from the built-in displacement transducers or externally installed transducers placed between the machine platens. However, the recorded axial strain in the ascending branch is not purely concrete deformations but includes some additional deformation because of machine flexibility and specimen’s end restraint. Strain gauges can be diametrically installed at the middle of specimen for a more precise deformation reading but additional costs are required for the gauges and data acquisition system. Moreover, the concrete stress–strain curve and ductility performance beyond its ultimate is difficult to be recorded without special strain measuring devices. Hence, a correction equation is needed to account for these effects to obtain the complete stress–strain curves for unconfined and confined concrete. In this paper, a total number of 84 unconfined and steel strapping tensioning techniques (SSTTs) confined high-strength concrete cylinders of compressive strength ranging from 62.48 MPa to 184.85 MPa were tested in compression in accordance with ASTM C39/C39M-11. The details for the testing setup, testing machine, strain measuring instruments, loading rate, loading patterns, etc. are described and at the same time a correction factor equation is proposed in this paper.

Improving local ventilation prediction by accounting for inter-segmental ventilation

The inter-segmental ventilation rate at clothing inter-connection of arms and trunk affects the estimation of local ventilation rates of these clothed segments. The accurate estimation of the inter-segmental ventilation rate is based on the integration of a connected clothed cylinders model with a bio-heat model to predict a realistic segmental skin temperature. This integration is validated with experiments on a thermal manikin using the tracer gas method. The results show that accounting for the inter-segmental ventilation rate improves the estimation of the segmental ventilation of the arm and the trunk for different garment apertures at external wind velocities less than 4 m/s. For a wind velocity of 1 m/s, the inter-connection increased the trunk ventilation by up to 12% and heat loss by up to 5.46%. A statistical correlation is established for the inter-segmental ventilation rate in terms of the influencing parameters: air permeability, wind velocity, mean air gap size between skin and clothing, and the upper clothing aperture design. Furthermore, a local ventilation rate correction factor equation is developed as a function of the inter-segmental ventilation rate to correct for local ventilation rates when derived from values of isolated/unconnected clothed segments.

Correction Factors for Photocell Sprint Timing With Flying Start.

A review of published studies monitoring sprint performance reveals considerable variation in start distance behind the initial timing gate. The aim of the current study was to generate correction factors across varying flying-start distances used in sprint testing with photocells. Forty-four well-trained junior soccer players (age 18.2 ± 1.0 y, height 175 ± 8 cm, body mass 68.4 ± 8.9 kg) performed sprint testing on an indoor sprint track. They were allocated to 3 groups based on sprint-performance level. Times for 10- and 200-m sprint with foot placement ranging from 0.5 to 15 m back from the initial timing gate were recorded twice for each athlete. Correction-factor equation coefficients were generated for each of the 3 analyzed groups derived from the phase-decay equation y = (y0 - PL) × exp(-k × x) + PL, where y = time difference (0.5-m flying start as reference), x = flying-start distance, y0 is the y value when time is zero, PL (plateau) is the y value at infinite times, and k is the rate constant, expressed in reciprocal of the x-axis time units; if x is in seconds, then k is expressed in inverse seconds. R2 was ≥.998 across all athlete groups and sprint distances, demonstrating excellent goodness of fit. Within-group time differences were significant (P < .05) across all flying-start distance checkpoints for all groups. Between-groups time-saving differences up to 0.04 s were observed between the fastest and the slowest groups (P < .05). Small changes in flying-start distances can cause time differences larger than the typical gains made from specific training, or even the difference between the fastest and slowest elite team-sport athletes. The presented correction factors should facilitate more meaningful comparisons of published sprint-performance results.

Cystatin C- and creatinine-based equations in the assessment of renal function in HIV-positive patients prior to commencing Highly Active Antiretroviral Therapy.

We evaluated the accuracy and precision of creatinine- and cystatin C-based prediction equations for estimating glomerular filtration rate compared to measured glomerular filtration rate in an antiretroviral-naive human immunodeficiency virus population. The study population consisted of 100 treatment-naive HIV patients. Glomerular filtration rate was estimated using the Cockcroft-Gault, Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations, as well as cystatin C-based equations (CKD-EPIcystatin C, cystatin Cvan Deventer and CKD-EPIcombined)) compared to (51)Cr-EDTA plasma clearance-measured glomerular filtration rate. We calculated percentage bias, standard deviation of the differences, accuracy within 15 and 30% of measured glomerular filtration rate and sensitivity and specificity for predicting measured glomerular filtration rate <60 mL/min/1.73 m(2). Bias for all estimating glomerular filtration rate equations ranged from -9.4% to 38.4%. The CKD-EPIcombined without ethnicity correction factor equation had the least bias, 2.9% (-2.9 to 8.8). Bias was higher for the Modification of Diet in Renal Disease and CKD-EPI equation with the African-American ethnicity factor (38.4 and 33.7%) than without (14.2 and 15.3%). Standard deviation of the differences ranged from 29.2% (CKD-EPIcombined without ethnicity factor) to 54.0% (Modification of Diet in Renal Disease with ethnicity factor). Accuracy within 30% of measured glomerular filtration rate ranged from 78% for CKD-EPIcombined without ethnicity factor to 56.7% for the Cockcroft-Gault equation. Sensitivity for creatinine-based equations was less than 50% and for the CKD-EPIcystatin C equation was 75%. Sensitivity of creatinine-based equations for predicting glomerular filtration rate was poor in this group of patients. The CKD-EPIcombined equation performed better than creatinine-based equations.

Refrigerating characteristics of ice storage capsule for temperature control of coal mine refuge chamber

Heat transfer process and refrigerating characteristics of ice melting enclosed in a cube capsule are investigated using experiments and mathematical relations to achieve temperature control by ice storage in coal mine refuge chamber. The effective refrigerating time for ice storage capsule is defined and tested. The mathematical relations of the effective refrigerating time and refrigeration rate are derived and modified. The correction factor equation of ambient temperature and humidity is established for the revision of mathematical relations. By using the modification factor equation, the mean relative error between modified and experimental values is less than 1%. The three application parameters, namely tmodified, Ncapsule, and Nt,capsule are obtained based on the experiments and the modified relations. These parameters form the temperature control strategies in using ice storage capsule for refuge chamber. A 24-h manned experiment verifies the accuracy of the temperature control strategies.

Fatigue crack propagation analysis for welded joint subjected to bending

In this paper, fatigue tests have been conducted on specimens, which are flat plate with a notch, stud-welded plate, T-shaped fillet welded joint and cruciform fillet welded joint, in such a way that fatigue cracks could be initiated and propagated in bending load. Under bending load, surface crack has formed flat semi-ellipse and propagated to about 80% of plate thickness before failure. Besides, the fatigue crack propagation life of cracked welded joint specimen has been predicted using fracture mechanics method. In particular, a correction factor equation has been developed for covering linearly varying stress distribution along crack propagation path under bending load. This equation has been applied to calculating stress intensity factor (SIF) in relation to fatigue life prediction.

Numerical Study on the Particle Movement of a Particle-Laden Impinging Jet

The purpose of this study is to analyze numerically the movement of particles included in turbulent fluid flow characteristics of metallic surfaces. To describe fluid flew, the incompressible Navier-Stokes equation discretized by the finite volume method were solved on the non-orthogonal coordinates with non-staggered variable arrangement, and the k- turbulence model was adapted. After fluid flow was calculated, particle movement was predicted from the Lagrangian approaches. Non-essential complexities were avoided by assuming that the particles had spherical shapes and the Stoke's drag formula only consisted of external farces acting upon them. In order to validate the numerical calculations, the results were compared with the experimental data reported in literature and agreed well with them. The drag force coefficient equation showed better agreement with the experimental data in the prediction of particle movement than the correction factor equation. Impact velocity and impact angle increased as inlet turbulence intensity decreased, relative jet height was lower. or the Reynolds number was larger.

A Three-Dimensional Correction Factor Equation for Deviated Wells: ABSTRACT

A Three-Dimensional Correction Factor Equation for Deviated Wells: ABSTRACT

Lens Distortion Equation Using Moiré

A technique for deriving the distortion equation of a lens system using moiré fringes is introduced, from which a correction factor equation is derived, making it unnecessary to use high quality lenses to make absolute measurements, as applicable to strain measuring instrumentation.

Wall effect for the fall of single drops

AbstractMeasurements were made of the rate of fall of drops of five organic liquids through an aqueous phase contained in eight vertical cylinders of various diameters. Newton's equation for the wall proximity effect for rigid spheres or cylinders predicts values somewhat in excess of the observed. A correction factor equation with the more convenient equivalent spherical diameter is presented. Its use is limited to d/D ratios less than one half. The ultimate velocity of a drop of specific size in an infinite medium can be calculated from that measured in a small tube by multiplying the latter by the ratio of the tube cross‐sectional area to the area of the annular space between tube wall and drop.