Proficiency Testing in Chemical Analysis of Iron Ore: Comparison of Statistical Methods for Outlier Rejection

Participation in proficiency testing (PT) is an important task to meet the requirements of ISO/IEC 17025 in the area of quality assurance of laboratory results. A PT program in the field of chemical analysis of iron ore was organized by CSIR-National Metallurgical Laboratory, Jamshedpur (nodal laboratory) and CSIR-National Physical Laboratory, New Delhi (PT Coordinator) during November 2011–January 2012. Twenty-two (22) laboratories in India participated in the PT program. The results of participating laboratories were first analyzed to identify the distribution patterns and the presence of outliers. Several parametric and robust statistical methods were used to identify the outliers. Correct outlier rejection is of utmost importance because the choice of the outlier test method influence the consensus value and standard deviation which in turn determine the Z-score of a laboratory result in a PT program. In the present study, five parametric outlier tests were compared: Dixon’s Q test, Grubbs single test, double test, t test, and Z-scores. In addition three robust tests as alternative to parametric tests were chosen: box plot, Huber test and MAD-based test. It was observed that multiple outlier test methods should be used to identify the outliers in a PT program especially when the number of participating laboratories is less. They complement each other and helps give diverse information and better overview of the data set. Among the 22 participating laboratories, Z-scores of 4 laboratories for analysis of total iron fall outside the acceptable limit of ±2. Similarly, for analysis of alumina and silica, five laboratories had unacceptable Z-scores.     

Sodar studies of some atmospheric boundary layer parameters during a solar eclipse

Sodar observations of the atmospheric boundary layer during the solar eclipse of 24 October 1995 have been examined for three different topographical stations in India. The celestial phenomenon occurred almost at the morning transitional time when night-time stable conditions were giving way to day-time unstable conditions. The echograms (sodar records) have been examined with special reference to the delay in break-up of inversion on the eclipse day. The delay was clearly reflected on the echograms of the same site when compared with the eroding inversion on a preceding/subsequent normal day. Doppler sodar data suggest a compression in vertical wind velocity and turbulence due to the increased stability during the eclipse phase.     

Near perfect thin film flexible broadband optical absorber with high thermal/electrical conductivity

Flexible ultra-black absorber with high thermal/electrical conductivity finds huge applications in the field of stray light attenuation, solar collectors, flexible electronics, and electronic thermal management systems. In this work, we report the fabrication of ultrablack absorber consists of vertically aligned carbon nanotubes (VACNT) in Polydimethylsiloxane (PDMS) having an absorption capacity of more than 98% in UV–Vis wavelength and more than 94% in NIR wavelength range. It is observed that the PDMS-VACNT composite shows ultra-high absorption capacity due to enhanced impedance matching and multiple scattering. In addition to this, the PDMS-VACNT composite shows an emissivity of 0.94 along with a 118% increase in thermal conductivity. Moreover, with the infiltration of VACNT in PDMS, the sheet resistance decrease drastically to 0.08 KΩ/sq, which signify the possible use of ultrablack absorber in electronic skin and flexible sensors etc. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48855.     

Performance analysis of cooperative spectrum monitoring in cognitive radio network

Wireless Networks - The imperfect spectrum monitoring (SM) is a major obstacle to detect the emergence of primary user (PU) quickly during the cognitive users’ (CUs’) data transmission...     

An Efficient Compression of Gray Scale Images Using Wavelet Transform

Wireless Personal Communications - In the field of digital image distribution and reproduction, the standardization of digital photography and the recent advancement in technology have led to...     

Adviser: immersive field work for planetary geoscientists

The Adviser prototype system makes it possible for planetary geologists to conduct virtual field research on remote environments such as Antarctica and Mars. Among Adviser's interactive tools are mission-planning and measurement tools that let researchers generate new data and gain interpretive insights. Five case studies illustrate the system's applications and observed benefits.