Microprocessor control systems have been developed for dual fuel diesel engines intended for transportation applications. Control system requirements for transportation engines are more demanding than for stationary engines, as the system must be able to cope with variable speed and load. Detailed fuel maps were determined for both normally aspirated and turbocharged diesel engines based on the criterion that the engine did not operate in the regimes where knock or incomplete combustion occurred. The control system was developed so that the engine would follow the detailed fuel map. The input variables to the control system are engine speed and load. Based on this, the system then controls the amount of natural gas and diesel fuel supplied to the engine. The performance of the system will be briefly summarized.

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Estimates of turbulent burning speed, burning zone thickness, and randomness of ignition delay have been incorporated in a model of spark-ignited engine combustion. The estimates have been made on the assumption that turbulence during combustion is homogeneous, isotropic, and has Tennekes’ small-scale structure with integral length scale proportional to chamber height. Flame propagation rate has been assumed to depend on turbulence intensity in accord with Chomiak’s vortex-bursting hypothesis. The resulting method of calculating combustion has been tested with cylinder pressure data from a Ricardo single-cylinder engine over a wide range of rpm and equivalence ratio and operating with natural gas fuel. Hot-wire measurements of turbulence intensity were made in the motored engine, but window-averaged estimates of intensity were a factor of two lower than ensemble-averaged estimates. Given a factor of two uncertainty in the turbulence intensity measurements it can be said that estimates of combustion duration and pressure agreed well with experimental data over the range of speed and equivalence ratio. The sensitivity of the calculation method to alterations in assumed parameters has been tested. The most important uncertainty appears to be the turbulence intensity.

The coronavirus disease (COVID-19) pandemic shows the rapid pace at which vaccine development can occur which highlights the need for more fast and efficient analytical methodologies to track and characterize candidate vaccines during manufacturing and purification processes. The candidate vaccine in this work comprises plant-derived Norovirus-like particles (NVLPs) which are structures that mimic the virus but lack any infectious genetic material. Presented here is a liquid chromatography-tandem mass spectrometry (LC-MS/MS) methodology for the quantification of viral protein VP1, the main component of the NVLPs in this study. It combines isotope dilution mass spectrometry (IDMS) with multiple reaction monitoring (MRM) to quantify targeted peptides in process intermediates. Multiple MRM transitions (precursor/product ion pairs) for VP1 peptides were tested with varying MS source conditions and collision energies. Final parameter selection for quantification includes three peptides with two MRM transitions each offering maximum detection sensitivity under optimized MS conditions. For quantification, a known concentration of the isotopically labeled version of the peptides to be quantified was added into working standard solutions to serve as an internal standard (IS); calibration curves were generated for concentration of native peptide vs. the peak area ratio of native-to-isotope labeled peptide. VP1 peptides in samples were quantified with labeled versions of the peptides added at the same level as that of the standards. Peptides were quantified with limit of detection (LOD) as low as 1.0 fmol/μL and limit of quantitation (LOQ) as low as 2.5 fmol/μL. NVLP preparations spiked with known quantities of either native peptides or drug substance (DS) comprising assembled NVLPs produced recoveries indicative of minimal matrix effects. Overall, we report a fast, specific, selective, and sensitive LC-MS/MS strategy to track NVLPs through the purification steps of the DS of a Norovirus candidate vaccine.

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