arXiv subjects

Neeraj Joshi

Publications and source records attributed to Neeraj Joshi.

4 recordsLinked to original sources

arXiv2026

A minimum-risk and cost-efficient two-sample sequential testing framework for the shifted exponential models with application to precipitation data

This paper investigates the problem of comparing the location parameters of two shifted exponential models through a novel double sequential sampling framework. The proposed hypothesis testing procedure is developed by controlling the type I error probability at a preassigned level while minimizing a loss function that incorporates both the type II error probability and the associated sampling cost. The corresponding optimal fixed-sample-size expressions are shown to depend on unknown scale parameters, rendering the desired testing accuracies unattainable in practice under fixed-sample designs. To overcome this difficulty, a double sequential sampling procedure is proposed to test the difference between location parameters when the scale parameters are unknown and unequal. The proposed methodology is shown to possess desirable asymptotic properties, including first-order efficiency, second-order efficiency, and second-order risk efficiency. Extensive simulation studies and a real-data application that involves heavy precipitation episodes at meteorological stations demonstrate the practical effectiveness and applicability of the proposed procedure.

stat.ME↗

arXiv2026

Likelihood-Based Regression for Weibull Accelerated Life Testing Model Under Censored Data

In this paper, we investigate accelerated life testing (ALT) models based on the Weibull distribution with stress-dependent shape and scale parameters. Temperature and voltage are treated as stress variables influencing the lifetime distribution. Data are assumed to be collected under Progressive Hybrid Censoring (PHC) and Adaptive Progressive Hybrid Censoring (APHC). A two-step estimation framework is developed. First, the Weibull parameters are estimated via maximum likelihood, and the consistency and asymptotic normality of the estimators are established under both censoring schemes. Second, the resulting parameter estimates are linked to the stress variables through a regression model to quantify the stress-lifetime relationship. Extensive simulations are conducted to examine finite-sample performance under a range of parameter settings, and a data illustration is also presented to showcase practical relevance. The proposed framework provides a flexible approach for modeling stress-dependent reliability behavior in ALT studies under complex censoring schemes.

stat.ME↗

arXiv2022

Lithography Free Process for the Fabrication of Periodic Silicon Micro/Nano-Wire Arrays and Its Light-trapping Properties

Vertically aligned silicon micro/nanowire arrays of different sizes have been synthesized by combining the modified metal-assisted chemical etching (MACE) and reactive ion etching (RIE) methods. This is a novel lithography-free method to fabricate silicon micro/nanowire arrays. The size of micro/nanowire arrays is controlled by controlling the etching rate and diameter of silica particles. The silicon micro/nanowire geometry can utilize for efficient collection of photo-generated charge carriers from impure silicon wafers, which have a short minority carrier diffusion length also act as a self-antireflection coating layer. For micro/nanowire having average diameters of 40 nm, 330 nm and 950 nm and their corresponding average length 1.12 micron, 1.1 micron, and 1 micron, respectively, the observed average reflectance was 0.22, 0.6 and 0.33 percent at 45-degree incident angle, while the average reflectance was increased up to 4.2, 9.2, and 11 percent, respectively at 75-degree incident angle in the broad range of 300 - 1200 nm of the solar spectrum. The measured average reflectance for these samples is quite low compared to the planar silicon wafer. Thus this geometry is a promising candidate for fabricating low-cost and highly efficient radial junction silicon micro/nanowire arrays based solar cells.

cond-mat.mtrl-sci↗

arXiv2022

Lithography free method to synthesize the ultra-low reflection inverted-pyramid arrays for ultra-thin silicon solar cell

Silicon inverted pyramids arrays have been suggested as one of the most promising structure for high-efficient ultrathin solar cells due to their ability of superior light absorption and low enhancement of surface area. However, the existing techniques for such fabrication are either expensive or not able to create appropriate structure. Here, we present a lithography free method for the fabrication of inverted pyramid arrays by using a modified metal assisted chemical etching (MACE) method. The size and inter-inverted pyramids spacing can also be controlled through this method. We used an isotropic chemical etching technique for this process to control the angle of etching, which leads to ultra-low reflection, even < 0.5%, of this nanostructure. Using this specification, we have predicted the expected solar cell parameters, which exceeds the Lambertian limit. This report provides a new pathway to improve the efficiency of the ultrathin silicon solar cells at lower cost.

cond-mat.mtrl-sci↗