Portable remote laser sensor for methane leak detection

A portable laser system for remote detection of methane gas leaks and concentrations is disclosed. The system transmitter includes first and second lasers, tuned respectively to a wavelength coincident with a strong absorption line of methane and a reference wavelength which is weakly absorbed by methane gas. The system receiver includes a spherical mirror for collecting the reflected laser radiation and focusing the collected radiation through a narrowband optical filter onto an optial detector. The filter is tuned to the wavelength of the two lasers, and rejects background noise. The output of the optical detector is processed by a lock-in detector synchronized to the chopper, and which measures the difference between the first wavelength signal and the reference wavelength signal

Strategic adoption of logistics and supply chain management

© 2018, Emerald Publishing Limited. Purpose: The purpose of this paper is to develop a thorough understanding of the adoption of logistics and supply chain management (SCM) in practice, particularly at a strategic level, through an investigation of the four perspectives taxonomy of the relationship between logistics and SCM. Design/methodology/approach: Based on a comprehensive literature review, three specific research questions are proposed. The empirical work addresses these questions and comprised three phases: focussed interviews, a questionnaire survey and focus groups. Findings: The findings provide a usage profile of the four perspectives and indicate a divergence between the understanding and adoption of logistics and SCM principles and concepts at a strategic level in firms. The findings also identify the critical success factors (CSFs) and inhibitors to success in addressing this divergence. Research limitations/implications: The insights generated using the authors’ methodologically pluralist research design could be built upon to include case studies, grounded theory and action research. Replicating the research in other geographical areas could facilitate international comparisons. Practical implications: The findings allow practitioners to compare their perspectives on the relationship between logistics and SCM with those of their peers. The CSFs and inhibitors to success provide a rational basis for realising the strategic potential of logistics and SCM in practice. Originality/value: New insights are generated into practitioner perspectives vis-à-vis logistics vs SCM. A fresh understanding of those factors which drive and hinder the adoption of strategic SCM is also developed and presented

Molecular dynamics simulation studies of the influence of imidazolium structure on the properties of imidazolium/azide ionic liquids

Journal ArticleAtomistic molecular dynamics simulations were performed on 1-butyl-3-methyl-imidazolium azide [bmim][N3], 1-butyl-2,3-dimethylimidazolium azide [bmmim][N3], and 1-butynyl-3-methylimidazolium azide [bumim][N3] ionic liquids. The many-body polarizable APPLE&P force field was augmented with parameters for the azide anion and the bumim cation. Good agreement between the experimentally determined and simulated crystal structure of [bumim][N3] as well as the liquid-state density and ionic conductivity of [bmmim][N3] were found. Methylation of bmim (yielding bmmim) resulted in dramatic changes in ion structuring in the liquid and slowing of ion motion. Conversely, replacing the butyl group of bmim with the smaller 2-butynyl group resulted in an increase of ion dynamics