Radio refractivity observations over the oceans using airborne microwave refractometer in tropics

The coastal waters of Indian sub -continent do not have reliable measurements of fine structure of radio refractivity especially in near real-time basis needed to mitigate the effects of anomalous propagation for the defence communications as well as for antisubmarine warfare. This programme was designed to document the radio refractive layer structure and variations of the marine layer in tropical waters of India. The paper describes the above observations taken using the airborne microwave refractometer developed by the author at National Physical Laboratory, New Delhi. Typical observations taken (for the first time in India) under normal and anomalous propagation conditions are presented and the results are compared with the special shipborne observations made under MONEX operation over the coastal waters of India.

Investigation of contribution of number of trials in Monte Carlo simulation for uncertainty estimation for a pressure balance

It is well established that the estimation of measurement uncertainty is vital for the validation of any measurement and is an essential parameter of quality assurance. Apart from the conventional technique of law of propagation of uncertainty (LPU), which has many limitations, Monte Carlo simulation (MCS) technique has become an essential tool for the estimation of measurement uncertainty in various fields of metrology. The most critical factor in MCS is the generation of random numbers of the input quantities according to their probability distributions. The number of Monte Carlo trials to generate these random numbers significantly affects the results. In particular, the required number of trials is also affected by the parameter for which the uncertainty is to be estimated. Hence, in the current paper, the effect of selection of the number of trials on the random number generation and the resulting output in terms of standard deviation (SD) is investigated for the uncertainty in the effective area of a pneumatic reference pressure standard (NPLI-4) at the CSIR-National Physical Laboratory of India. The simulation results thus obtained are compared amongst themselves, with an adaptive approach as well as with the experimental results. The outcomes are analyzed and discussed in detail.

Alan Turing and Oxford

Did Alan Turing OBE FRS (23 June 1912 – 7 June 1954), the celebrated mathematician, codebreaker, and pioneer computer scientist, ever visit Oxford? He is well-known for his connections with the University of Cambridge, Bletchley Park, the National Physical Laboratory, and the University of Manchester, but there is no known written archival record of him ever visiting Oxford, despite it being the location of the University of Oxford, traditionally a rival of Cambridge. However, surely he must have done so.

Hydrogen Gas Quality for Gas Network Injection: State of the Art of Three Hydrogen Production Methods

The widescale distribution of hydrogen through gas networks is promoted as a viable and cost-efficient option for optimising its application in heat, industry, and transport. It is a key step towards achieving decarbonisation targets in the UK. A key consideration before the injection of hydrogen into the UK gas networks is an assessment of the difference in hydrogen contaminants presence from different production methods. This information is essential for gas regulation and for further purification requirements. This study investigates the level of ISO 14687 Grade D contaminants in hydrogen from steam methane reforming, proton exchange membrane water electrolysis, and alkaline electrolysis. Sampling and analysis of hydrogen were carried out by the National Physical Laboratory following ISO 21087 guidance. The results of analysis indicated the presence of nitrogen in hydrogen from electrolysis, and water, carbon dioxide, and particles in all samples analysed. The contaminants were at levels below or at the threshold limits set by ISO 14687 Grade D. This indicates that the investigated production methods are not a source of contaminants for the eventual utilisation of hydrogen in different applications including fuel cell electric vehicles (FCEV’s). The gas network infrastructure will require a similar analysis to determine the likelihood of contamination to hydrogen gas.

Research Organizations in British Shipbuilding and Large Marine Engine Manufacture: 1900-1945 (Part I)

Cet article est le premier d’une série de trois sur les organismes de recherche en construction navale britannique et en fabrication de gros moteurs marins (diésel et à turbine). Dans cette première partie, qui traite de la période 1900-1945, l’auteur analyse les antécédents et la création ultérieure de deux associations de recherche propres à l’industrie, soit la British Shipbuilding Research Association et la Parsons Marine Turbine Research and Development Association, toutes deux créées en 1944. Il traite également de William Doxford & Sons, le premier fabricant britannique de moteurs diésel marins à faible vitesse établi sur la rivière Wear à Sunderland et, tangentiellement, du National Physical Laboratory, une institution financée par l’État, et sa division des navires.

Indelible ink dermatitis during COVID: A series of 97 cases

Indelible ink is formulated by National Physical Laboratory and produced by Mysore Paints and Varnishes Limited since 1962. It is most used to prevent voter fraud in elections. The ink’s believed to be composed of silver nitrate (7%–25%), which binds to the proteins in skin and nails. The ink is said to be relatively safe at this concentration. However, frequent exposure, older ink, and higher concentrations can result in cumulative exposure and various degrees of damage. Herein, we report irritation reactions with the ink in several students labelled for home quarantine during COVD19 pandemic. Overall, 97 students (aged 15–17 years) with travel history were screened and quarantined according to COVID19 protocols. They were stamped with “HOME QUARANTINE” on the ventral aspect of the right forearm. Approximately 4-6 hours later, all students complained of localised burning and swelling to a variable extent. The severity was more in girls. They were treated with topical antibiotics, steroids and cetirizine tablets which showed symptomatic improvement. Irritation with indelible ink has rarely been reported, especially, with a large sample size. This report highlights the risk of severe irritant dermatitis with indelible ink and hence the need for its judicious use.

Bioinspired Microstructures Polymer Surfaces with Antireflective Properties

Antireflective (AR) coatings have been around for more than a century, with the simplest form dating back to Lord Rayleigh’s 1886 tarnished glass. Different approaches to obtaining AR coatings exploit index-matching, interference, or absorbing phenomena. In 2002, a novel super black surface was developed by Brown et al. at the National Physical Laboratory in the UK and soon gained significant interest among both academia and industry. Since then, scientists have been competing in a race to produce the blackest material. Although extremely valuable, existing solutions usually require complicated fabrication procedures and post-application treatments. Structural colors are ubiquitous in nature, so an interesting approach to developing AR coatings is biomimicry. Moth-eye structures are well-known for their AR properties, and they have been successfully replicated using micro- and nanofabrication methods and employed as AR coatings. Interestingly, recent studies from Harvard University highlight two types of microstructures that lead to super black coloring in nature, i.e., barbule microstructures on birds of paradise and cuticular bumps on peacock spiders. These publications provide detailed information on the shape of such natural super black microstructures and mechanisms behind the observed super black effect. Although the replication of such structures should prove extremely valuable, it has not yet been demonstrated. In this paper, we present the fabrication and characterization of AR microarrays inspired by the peacock spiders’ super black structures encountered in nature. Fabrication is done by super-resolution three-dimensional (3D) printing using two-photon polymerization of an acrylic resin. The optical properties of microstructure arrays with different shape design parameters are then characterized using a homemade reflectance/transmittance setup, which allows wavelength-dependent investigations in the ultraviolet, visible, and near-infrared ranges. The influence of the shape design parameters on the optical properties of the microarrays is then discussed with experimental measurements as well as simulations.

Importance of Standards in Biomedical Device and Its Role in Strengthening the Healthcare Sector

Biomedical Metrology group of CSIR-NPL (Council of Scientific and Industrial Research—National Physical Laboratory), India is contributing significantly for establishing National Biomedical equipment standardswhich are traceable to primary standards to cater the quality control regulation in Health sector. This initiative has great impact on the health policy and Nation's economy as well. The laboratory has recently established biomedical equipment standard facility and disseminated the services to Industries, stake holders, hospitals and accredited laboratories. Although, the laboratory is successfully providing biomedical equipment calibration services for last 2 years, the sensitization of the information on the recently established metrological capabilities is required, which has great implications in implementation of India's New medical Device rule 2017 effectively. The present paper describes the summary on the significant achievements and role of National Physical Laboratory in supporting the Indian medical device regulations.