Prediction of rail defect development using parametric bootstrapping modified Weibull equations

The railroad industry has historically used the 2-Parameter Weibull equation to determine the rate of rail fatigue defect occurrences and to forecast the fatigue life of railroad rail. However, the 2-Parameter Weibull equation has significant limitations to include inability to analyze segments of track with limited number of rail defects. These limitations are addressed through modification of the traditional 2-Parameter Weibull equation with a novel approach developed from Parametric Bootstrapping. The result is a Parametric Bootstrapping modified Weibull (PBW) forecasting approach. This methodology is applied to rail segments with insufficient numbers of defects to allow for appropriate defect forecasting analysis. Thus, the PBW method provides reasonable estimates of the rate of defects for track segments that have little or no prior defect history. This approach allows for more track to be analyzed and forecasts the probability of rail defect occurrence as a function of key parameters such as cumulative traffic over the rail. A validation of the proposed methodology was performed. Comparison of the output results of over 300,000 track segments with over 200,000 rail defects showed a major improvement in percentage of segments with reasonable Weibull parameters (alpha and beta). This percentage increased from 11% of segments using traditional Weibull analysis to 77% of segments using Parametric Bootstrap modified Weibull approach. These results show that the PBW Analysis approach introduced here offers a more accurate and effective approach to determining the probability of developing future rail defects. This provides a benefit to railroads in planning maintenance of their expensive rail assets.

The Preparation, Determination of a Flexible Complex Liposome Co-Loaded with Cabazitaxel and β-Elemene, and Animal Pharmacodynamics on Paclitaxel-Resistant Lung Adenocarcinoma

Paclitaxel is highly effective at killing many malignant tumors; however, the development of drug resistance is common in clinical applications. The issue of overcoming paclitaxel resistance is a difficult challenge at present. In this study, we developed nano drugs to treat paclitaxel-resistant lung adenocarcinoma. We selected cabazitaxel and β-elemene, which have fewer issues with drug resistance, and successfully prepared cabazitaxel liposome, β-elemene liposome and cabazitaxel-β-elemene complex liposome with good flexibility. The encapsulation efficiencies of cabazitaxel and β-elemene in these liposomes were detected by precipitation microfiltration and microfiltration centrifugation methods, respectively. Their encapsulation efficiencies were all above 95%. The release rates were detected by a dialysis method. The release profiles of cabazitaxel and β-elemene in these liposomes conformed to the Weibull equation. The release of cabazitaxel and β-elemene in the complex liposome were almost synchronous. The pharmacodynamics study showed that cabazitaxel flexible liposome and β-elemene flexible liposome were relatively good at overcoming paclitaxel resistance on paclitaxel-resistant lung adenocarcinoma. As the flexible complex liposome, the dosage of cabazitaxel could be reduced to 25% that of the cabazitaxel injection while retaining a similar therapeutic effect. It showed that β-elemene can replace some of the cabazitaxel, allowing the dosage of cabazitaxel to be reduced, thereby reducing the drug toxicity.

A SINGLE-BAMPLE METHOD FOR ESTIMATING RESISTANCE OF PARTS

The determination of the individual characteristics of the fatigue resistance of the objects is proposed using fractographic analysis of their fractures, which gives an approximate estimate of the voltage corres-ponding to one cycle and allows one to construct an oblique portion of the fatigue curve from the test of one object and calculate the endurance limit from the Weibull equation.

Influence of Hydrophilic Polymers on theβFactor in Weibull Equation Applied to the Release Kinetics of a Biologically Active Complex ofAesculus hippocastanum

Triterpenoid saponins complex of biological origin, escin, exhibits significant clinical activity in chronic venous insufficiency, skin inflammation, epidermal abrasions, allergic dermatitis, and acute impact injuries, especially in topical application. The aim of the study is the comparison of various hydrogel formulations, as carriers for a horse chestnut seed extract (EH). Methylcellulose (MC), two polyacrylic acid derivatives (PA1 and PA2), and polyacrylate crosspolymer 11 (PC-11) were employed. The release rates of EH were examined and a comparison with the Weibull model equation was performed. Application of MC as the carrier in the hydrogel preparation resulted in fast release rate of EH, whereas in the case of the hydrogel composed with PC-11 the release was rather prolonged. Applied Weibull function adhered best to the experimental data. Due to the evaluated shape parameterβ, in the Weibull equation, the systems under study released the active compound according to the Fickian diffusion.

Using the Three-Stage Weibull Equation and Tree-Based Model to Characterize the Mix Fatigue Damage Process

The primary purpose of this paper is to demonstrate the applicability of the three-stage Weibull equation to describe the fatigue damage process using flexural controlled deformation fatigue tests. A data set of 179 beam fatigue tests originally designed for exploring the fatigue performance of conventional dense graded asphalt concrete (DGAC) and asphalt–rubber hot-mix gap-graded (ARHM-GG) mixes was used to inspect the three-stage Weibull parameters that were estimated using a genetic algorithm. The tree-based regression–category models were then used to uncover the data structure of the estimated parameters as a function of material properties, conditioning methods, temperatures, compaction methods, and strain levels. In general, the three-stage Weibull equation provides satisfactory fitting results for the three-stage fatigue damage process occurring in a beam test. It was found that the tree-based models of three-stage Weibull parameters associated with the crack initiation stage were statistically adequate and reliable compared with the models of parameters related to the warm-up stage and the crack propagation stage. It might suggest that these crack initiation parameters are better indexes to assess the fatigue performance.