University of Mass Lowell

Lowell, MA, United States

University of Mass Lowell

Lowell, MA, United States
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Rothman L.S.,Harvard - Smithsonian Center for Astrophysics | Gordon I.E.,Harvard - Smithsonian Center for Astrophysics | Babikov Y.,Zuev Institute of Atmospheric Optics | Barbe A.,CNRS Molecular and Atmospheric Spectrometry Group | And 47 more authors.
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2013

This paper describes the status of the 2012 edition of the HITRAN molecular spectroscopic compilation. The new edition replaces the previous HITRAN edition of 2008 and its updates during the intervening years. The HITRAN molecular absorption compilation is comprised of six major components structured into folders that are freely accessible on the internet. These folders consist of the traditional line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, infrared absorption cross-sections for molecules not yet amenable to representation in a line-by-line form, ultraviolet spectroscopic parameters, aerosol indices of refraction, collision-induced absorption data, and general tables such as partition sums that apply globally to the data. The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional absorption phenomena, and validity. Molecules and isotopologues have been added that address the issues of atmospheres beyond the Earth. Also discussed is a new initiative that casts HITRAN into a relational database format that offers many advantages over the long-standing sequential text-based structure that has existed since the initial release of HITRAN in the early 1970s. © 2013 Elsevier Ltd.

Jacquemart D.,University Pierre and Marie Curie | Jacquemart D.,French National Center for Scientific Research | Laraia A.,University of Mass Lowell | Kwabia Tchana F.,University Pierre and Marie Curie | And 6 more authors.
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2010

Self- and N2-broadening coefficients of H2CO have been retrieved in both the 3.5 and 5.7-μm spectral regions. These coefficients have been measured in FT spectra for transitions with various J (from 0 to 25) and K values (from 0 to 10), showing a clear dependence with both rotational quantum numbers J and K. First, an empirical model is presented to reproduce the rotational dependence of the measured self- and N2-broadening coefficients. Then, calculations of N2-broadening of H2CO were made for some for 3296 ν2 transitions using the semi-classical Robert-Bonamy formalism. These calculations have been done for various temperatures in order to obtain the temperature dependence of the line widths. Finally, self- and N2-broadening coefficients, as well as temperature dependence of the N2-widths has been generated to complete the whole HITRAN 2008 version of formaldehyde (available as supplementary materials). © 2010 Elsevier Ltd.

Ma Q.,NASA | Tipping R.H.,University of Alabama | Gamache R.R.,University Of Mass Lowell
Molecular Physics | Year: 2010

With different choices of the cut-offs used in theoretical calculations, we have carried out extensive numerical calculations of the N2-broadend Lorentzian half-widths of the H2O lines using the modified Robert-Bonamy formalism. Based on these results, we are able to thoroughly check for convergence. We find that, with the low-order cut-offs commonly used in the literature, one is able to obtain converged values only for lines with large half-widths. Conversely, for lines with small half-widths, much higher cut-offs are necessary to guarantee convergence. We also analyse the uncertainties associated with calculated half-widths, and these are correlated as above. In general, the smaller the half-widths, the poorer the convergence and the larger the uncertainty associated with them. For convenience, one can divide all H 2O lines into three categories, large, intermediate, and small, according to their half-width values. One can use this division to judge whether the calculated half-widths are converged or not, based on the cut-offs used, and also to estimate how large their uncertainties are. We conclude that with the current Robert-Bonamy formalism, for lines in category 1 one can achieve the accuracy requirement set by HITRAN, whereas for lines in category 3, it is impossible to meet this goal. © 2010 Taylor & Francis.

Wu N.,University Of Mass Lowell | Wang W.,University Of Mass Lowell | Tian Y.,University Of Mass Lowell | Guthy C.,University Of Mass Lowell | Wang X.,University Of Mass Lowell
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

A novel ultrasound generator consisting of a single mode optical fiber with a layer of gold nanoparticles on its tip has been designed. The generator utilizes the optical and photo-acoustic properties of gold nanoparticles. When heated by laser pulses, a thin absorption layer made up of these nanoparticles at the cleaved surface of a single mode fiber generates a mechanical shock wave caused by thermal expansion. Mie's theory was applied in a MATLAB simulation to determine the relationship between the absorption efficiency and the optical resonance wavelengths of a layer of gold nanospheres. Results showed that the absorption efficiency and related resonance wavelengths of gold nanospheres varied based on the size of the gold nanosphere particles. In order to obtain the bandwidths associated with ultrasound, another MATLAB simulation was run to study the relationship between the power of the laser being used, the size of the gold nanosphere, and the energy decay time. The results of this and the previous simulation showed that the energy decay time is picoseconds in length. © 2010 SPIE.

Routsis A.,University Of Mass Lowell
Plastics Technology | Year: 2010

Some of the steps that need to be taken for scientific troubleshooting are discussed. Some of the factors that contribute to a good scientific troubleshooting process are filling, packing, and recovery. The scientific troubleshooter documents the process outputs, which are the results of the process when acceptable parts are produced. Many of these parameters are the same as the process input, but each of them will be consistent from one machine to another. The next step involved in the troubleshooting process after eliminated potential causes of problems involve comparing the existing process with the documented standard. It is best to start by reviewing the parameters that relate to a specific defect, as a well-documented process contains a variety of parameters. A scientific troubleshooter can use this information to help make educated decisions about parameters that need to be changed to bring the process back to the documented standard.

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