Optimal Test Plan of Step Stress Partially Accelerated Life Testing for Alpha Power Inverse Weibull Distribution under Adaptive Progressive Hybrid Censored Data and Different Loss Functions

Accelerated life tests are used to explore the lifetime of extremely reliable items by subjecting them to elevated stress levels from stressors to cause early failures, such as temperature, voltage, pressure, and so on. The alpha power inverse Weibull (APIW) distribution is of great significance and practical applications due to its appealing characteristics, such as its flexibilities in the probability density function and the hazard rate function. We analyze the step stress partially accelerated life testing model with samples from the APIW distribution under adaptive type II progressively hybrid censoring. We first obtain the maximum likelihood estimates and two types of approximate confidence intervals of the distributional parameters and then derive Bayes estimates of the unknownparameters under different loss functions. Furthermore, we analyze three probable optimum test techniques for identifying the best censoring under different optimality criteria methods. We conduct simulation studies to assess the finite sample performance of the proposed methodology. Finally, we provide a real data example to further demonstrate the proposed technique

Comparison between physical properties of ring-spun yarn and compact yarns spun from different pneumatic compacting systems

A comparative study pertaining to physical and mechanical properties of ring-spun yarn vis-à-vis compact yarns spun using three different compacting systems has been reported. Rieter (K-44), Toyota (RX-240) and Suessen (Fiomax) spinning machines have been used and the condensing process of the fibres in the yarn cross-section as per these compact spinning systems is accomplished pneumatically. Thus, a yarn of linear density 5.9 tex (100 Ne) is spun on the spinning systems using Egyptian cotton of the type Giza 86. One way Anova together with least significant difference are employed to feature the means of the properties of spun yarns and a significant difference among them is observed. According to the performed statistical analysis, there is a significant difference between ring - spun yarn properties and each of the pnuematic compact spun yarns. These compact-spun yarns are also found to differ significantly in terms of their physical and mechanical properties; however, they are all found superior to the ring-spun yarn

The value of b0 images obtained from diffusion-weighted echo planar sequences for the detection of intracranial hemorrhage compared with GRE sequence

AbstractPurposeOur aim was to evaluate the clinical utility of b0EPI images obtained from diffusion sequence for the detection of the intracranial hemorrhagic lesions, especially acute intracerebral bleeds thereby shorten the scan time particularly in the critical acute cases of stroke.Materials and methodsAmong all consecutive MR brain studies performed in our department last year, we retrospectively selected those who followed the following criteria: (1) clinically suspected or radiographically confirmed acute infarction or hemorrhage. (2) MRI imaging including DWI and T2∗ images. Sensitivity of hemorrhage detection, conspicuity of lesions, and diagnostic certainty were compared between the b0EPI and GRE sequences.ResultsThere were 77 hemorrhagic lesions with a variety of pathogeneses in various locations. 76/77 (98.7%) of these lesions were hemorrhagic (hypointense) on the GRE sequences, whereas 61 (79.2%) were characterized as hemorrhagic on b0EPI images, and 16 (20.8%) were not detected. The overall difference in hemorrhage conspicuity/diagnostic certainty between GRE and b0EPI sequences was statistically significant (P<.05).Conclusionb0EPI sequence, although shorter in acquisition time, was inferior to GRE imaging in the detection of acute and chronic intracerebral hemorrhage

Reliability analysis of the new exponential inverted topp–leone distribution with applications

The inverted Topp–Leone distribution is a new, appealing model for reliability analysis. In this paper, a new distribution, named new exponential inverted Topp–Leone (NEITL) is presented, which adds an extra shape parameter to the inverted Topp–Leone distribution. The graphical representations of its density, survival, and hazard rate functions are provided. The following properties are explored: quantile function, mixture representation, entropies, moments, and stress– strength reliability. We plotted the skewness and kurtosis measures of the proposed model based on the quantiles. Three different estimation procedures are suggested to estimate the distribution parameters, reliability, and hazard rate functions, along with their confidence intervals. Additionally, stress–strength reliability estimators for the NEITL model were obtained. To illustrate the findings of the paper, two real datasets on engineering and medical fields have been analyzed

A New Inverse Rayleigh Distribution with Applications of COVID-19 Data: Properties, Estimation Methods and Censored Sample

This paper aims at modelling the COVID-19 spread in the United Kingdom and the United States of America, by specifying an optimal statistical univariate model. A new lifetime distribution with three-parameters is introduced by a combination of inverse Rayleigh distribution and odd Weibull family of distributions to formulate the odd Weibull inverse Rayleigh (OWIR) distribution. Some of the mathematical properties of the OWIR distribution are discussed as linear representation, quantile, moments, function of moment production, hazard rate, stress-strength reliability, and order statistics. Maximum likelihood, maximum product spacing, and Bayesian estimation method are applied to estimate the unknown parameters of OWIR distribution. The parameters of the OWIR distribution are estimated under the progressive type-II censoring scheme with random removal. A numerical result of a Monte Carlo simulation is obtained to assess the use of estimation methods

A New Inverse Rayleigh Distribution with Applications of COVID-19 Data: Properties, Estimation Methods and Censored Sample

This paper aims at modelling the COVID-19 spread in the United Kingdom and the United States of America, by specifying an optimal statistical univariate model. A new lifetime distribution with three-parameters is introduced by a combination of inverse Rayleigh distribution and odd Weibull family of distributions to formulate the odd Weibull inverse Rayleigh (OWIR) distribution. Some of the mathematical properties of the OWIR distribution are discussed as linear representation, quantile, moments, function of moment production, hazard rate, stress-strength reliability, and order statistics. Maximum likelihood, maximum product spacing, and Bayesian estimation method are applied to estimate the unknown parameters of OWIR distribution. The parameters of the OWIR distribution are estimated under the progressive type-II censoring scheme with random removal. A numerical result of a Monte Carlo simulation is obtained to assess the use of estimation methods

Multi-objective Optimization of Woven Fabric Parameters Using Taguchi–Grey Relational Analysis

Optimization technique is mainly used to find out the optimal value of control factors which yield the best response variables. In the case of more than one response variable, the optimization process using the Taguchi approach will give a different set of optimal level for each response variable. Consolidating Taguchi method with grey relation analysis will give optimal levels of control factors for all response variables. In the present study, multi-response optimization based on Taguchi-grey relational analysis was conducted to maximize tensile strength, breaking extension and air permeability of cotton woven fabrics. Cotton woven fabric parameters such as weft yarn count, weave structure, weft yarn density with three levels, and twist factor of the weft yarn with two levels were used as control factors. Using full factorial design, 81 experiments will be conducted. Whereas, using the Taguchi approach and L18 orthogonal array in particular, these experiments will be reduced to 16 experiments. Using Taguchi-grey relational method, optimal combination of the control factors which yield the best-woven fabric properties under study were obtained

Real-time tele-operation and tele-walking of humanoid Robot Nao using Kinect Depth Camera

International audienceHumanoid robots are not easy to program, it's a challenging task, even if they come with an advanced high level programming interfaces, such as drag-and-drop applications, which are indeed less complex and save a lot of time, it still needs an experienced user to produce a high quality motion, especially for the natural human-like motions which are very hard to reproduce. This paper introduces a new technique to fully imitate the human body motion on a humanoid robot NAO in real time using the Kinect Depth Camera, OpenNI Framework and the Robot Operating System (ROS)

Development Of Image Processing Techniques For Core-Scale Characterization And Synthetic 3D-Printed Core Replicas

Fluid-flow physics in porous media has been continually simplified by assuming isotropic homogeneous media with minimal rock-fluid interactions. Such simplification did not reflect reality and retained the ability to understand the flow behavior essence in unconventional reservoirs. The developed physics should be reevaluated on ideal porous media, indeed, which has minimal geometrical and interaction uncertainties. Therefore, image processing techniques were utilized to processs the CT scans of core samples to construct ideal 3D-printed replicas for coreflooding experiments and simulation models. The results from both were then compared for vcalidation and cross check. Methods, Procedures, Process: Grayscale CT-scan of a Berea core sample was digitally binarized to segment the grains cloud in the scan. That cloud was meshed and triangulated to form a 3D-printable object. The processed object was 3D printed with different 3D printing technologies and materials. The gypsum-replica, which had the closest petrophysical properties to the original Berea, was extensively investigated through a CO2 huff and puff experiment simultaneously with its original, geomechanical UCS (uniaxial compression strength) test, Nitrogen sorption, MICP (Mercury Injection Capillary Pressure), and contact angle wettability measurement. Based on the image processed CT scan, a finite difference model was created in which the petrophysical characteristics, porosity and permeability, were inferred from the CT scan. The model was used to simulate a transient permeability experiment on the Berea sample and the CO2 huff and puff experiment. The 3D printable volume was also used to create a finite element model to simulate the UCS test on the replica. Figure 1 shows the 3D printed replicas with their original Berea along with the coreflooding and geomechanical simulation models based on the reconstructed CT scan. Results, Observations, Conclusions: The 3D printed replica was able to represent their original sample with close storage and transport capacities. The used image processing workflow generated a precise static model for black oil (transient permeability) and compositional simulation models (CO2 huff and puff) of both samples. The CO2 effect on the core sample was pictured after breaking the replica to check its interior, and the simulation model was able to predict a similar saturation distribution. The simulation results accurately matched the replica’s measured oil recovery, pressure distribution during the transient permeability test. After including the UCS test schedule, the model succeeded in generating fatigue iso-surfaces, stress and strain contours, failure limits and modes, force reactions inside the core sample. Novel/Additive Information: The proposed image processing can produce the physical specimens for tests along with the needed models to simulate these tests. 3D-printed core replicas, which are created by reconstructing cores’ CT scans by image processing, are valuable for repetitive and destructive experiments and obey the criterion of ideality for laboratory research. The created coreflooding and geomechanical models are robust and precise for developing and understanding the physics of fluid flow in porous media