Recent research in chemical plant operation shows increasing interest in dynamic process operation as part of designed operating strategy for reasons such as increased dependency on renewable energy, and process intensification. Conventional analyses of fixed bed reactors are developed for steady state optimization and may not be adequate for dynamic operation. In fact, the important metrics and targets in dynamic process design are not entirely clear. The first objective of this article is to provide a state-of-the-art survey categorize types of dynamic operation, and rank the available common modelling and analytical tools suitable for quantification of dynamic process variables. The article then examines a case study of 1D and 2D model differences in a methanol steam reforming reactor. The case study shows model prediction differences of up to 15% for conversion, and up to 50% for CO concentration at the outlet during extreme load changes. The study concludes that the complexity of analytical and numerical techniques for dynamic processes is notably higher compared to steady state analyses, but appropriate tools and procedures are currently lacking.
As discussed in Ref. [1], recent theoretical and numerical treatments [2, 3] have sought to express the plasma radiofrequency (RF) response as a nonlocal integral operator formulated in configuration space. Analytical expressions of the integral kernels are available for Maxwellian particle species. This approach enables (i) direct use of the finite element method (FEM) to model wave propagation and absorption in hot inhomogeneous fusion plasmas, (ii) local mesh-refinement, (iii) provides RF field representations suited to address tokamak geometry, and (iv) allows straightforward connection between plasma and antenna models. The present contribution focuses on the concrete application of this method, in an incremental way, developing codes and exploiting finite element codes/libraries.
Most women serving in the military do so during their reproductive life and enter service at a young gynecological age. This review provides an overview of the menstrual cycle and summarizes the evidence for menstrual cycle disturbances in the military and how these disturbances to the menstrual cycle impact health and performance in the military. Servicewomen often manage the practical challenges of menstruation and symptoms of the menstrual cycle or menstrual disturbances/dysfunction in an austere environment with no formalized support and/or education, and with unknown stigma and risks. Menstrual health in the military context implies that those who experience a menstrual cycle can access timely information, diagnosis, and support/treatment to achieve “a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity, in relation to the menstrual cycle.” Herein we describe how menstrual health is impacted in a multistressor environment, including nutrition (energy balance and energy availability, micronutrients, and microbiome), physical activity, and recovery (occupational tasks, sleep, psychological stress, environment), and how menstrual disturbances can affect occupational performance and the lived experience of the female workforce. We call for action of militaries worldwide to protect the health of Servicewomen to maximize their potential. Low representation, relatively recent full integration of women into the military workforce, and the exclusion of women from military research have led to policies developed from evidence on men, with the potential to impact the health and performance of Servicewomen.
Onboard methanol steam reforming (MSR) coupled with proton exchange membrane fuel cells (PEMFCs) is investigated as a pathway for maritime decarbonization. Joule heating, flue-gas heating, and condensing-steam heating of multitubular fixed-bed MSR reactors are compared using steady-state one-dimensional models and technological, economic, environmental, and safety indicators. Selected configurations achieved weighted-average methanol conversions higher than 99%. Joule heating produced inlet cold spots of 442–445 K, whereas condensing steam maintained nearly uniform temperatures of 477–478 K. Within the investigated candidate set, normalized aggregated sustainability indicators ranged from 0.64 to 0.88 for Joule heating, 0.87–0.96 for flue-gas heating, and 0.997–0.999 for condensing steam. Condensing-steam heating attained the highest aggregate ranking across the examined decision-making perspectives and aggregation procedures. These relative indicators are not absolute sustainability levels, and the ranking remains conditional on the investigated steady-state design space, system boundaries, model assumptions, and economic and emission factors.
