Simulation and real-time optimal scheduling: a framework for integration

Traditional scheduling and simulation models of the same system differ in several fundamental respects. These include the definition of a schedule, the existence of an objective function which orders schedules and indicates the performance of a given schedule according to specific criteria, and the level of fidelity at which the items are represented and processed through he system. This paper presents a conceptual, object-oriented, architecture for combining a traditional, high-level, scheduling system with a detailed, process- level, discrete-event simulation. A multi-echelon planning framework is established in the context of modeling end-to-end military deployments with the focus on detailed seaport operations

Red flags for the early detection of spinal infection in back pain patients

© 2019 The Author(s). Background: Red flags are signs and symptoms that are possible indicators of serious spinal pathology. There is limited evidence or guidance on how red flags should be used in practice. Due to the lack of robust evidence for many red flags their use has been questioned. The aim was to conduct a systematic review specifically reporting on studies that evaluated the diagnostic accuracy of red flags for Spinal Infection in patients with low back pain. Methods: Searches were carried out to identify the literature from inception to March 2019. The databases searched were Medline, CINHAL Plus, Web of Science, Embase, Cochrane, Pedro, OpenGrey and Grey Literature Report. Two reviewers screened article texts, one reviewer extracted data and details of each study, a second reviewer independently checked a random sample of the data extracted. Results: Forty papers met the eligibility criteria. A total of 2224 cases of spinal infection were identified, of which 1385 (62%) were men and 773 (38%) were women mean age of 55 (± 8) years. In total there were 46 items, 23 determinants and 23 clinical features. Spinal pain (72%) and fever (55%) were the most common clinical features, Diabetes (18%) and IV drug use (9%) were the most occurring determinants. MRI was the most used radiological test and Staphylococcus aureus (27%), Mycobacterium tuberculosis (12%) were the most common microorganisms detected in cases. Conclusion: The current evidence surrounding red flags for spinal infection remains small, it was not possible to assess the diagnostic accuracy of red flags for spinal infection, as such, a descriptive review reporting the characteristics of those presenting with spinal infection was carried out. In our review, spinal infection was common in those who had conditions associated with immunosuppression. Additionally, the most frequently reported clinical feature was the classic triad of spinal pain, fever and neurological dysfunction. This is an Open Access article distributed in accordance with the Creative Commons Attribution Non-Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

PORTSIM: An object-oriented port simulation

The development of an object-oriented port simulation (PORTSIM) that addresses military mobility issues will be described, with a brief description of the tool selection process. This system provides users with (1) a graphical user interface, (2) the ability to simulate military units through a specified port, with each individual cargo item (i.e. piece of equipment) represented, (3) utilization statistics for all port resources e.g. gates, staging areas, berths, inspectors, and material handling equipments, (4) utilization statistics for ships that arrive at the port, and (5) a graphical dynamic animation that allows for identification of bottlenecks and facilitates the playing of what-if scenarios to maximize throughput. Cargo is simulated from the time it arrives at a gate or end ramp to the time it is loaded onto a ship. Animation is directly integrated with the simulation to allow for modifications to the scenario while the simulation is running and to have the new parameters used from that point forward in time. The simulation is flexible and allows for multiple cargo types (breakbulk, container, and roll-on/roll-off) and multiple ship types

The driving effects of common atmospheric molecules for formation of clusters: the case of sulfuric acid, nitric acid, hydrochloric acid, ammonia, and dimethylamine

Understanding how secondary aerosols form in the atmosphere is one of the main uncertainties for a better understanding of global warming. Secondary aerosols form from gas-phase molecules that combine to create prenucleation complexes, which can then grow to form aerosols. The study of the formation of prenucleation complexes is difficult from both an experimental and theoretical point of view. Sulfuric acid has been linked to the formation of aerosols, yet the details of interactions are not understood. We have completed an exhaustive study of the formation of prenucleation complexes of three strong acids: sulfuric acid, nitric acid, and hydrochloric acid, combined with ammonia and dimethylamine bases, and three water molecules. By combining an evolutionary algorithm search routine with density functional geometry optimizations and single-point electronic energy calculations with complete basis set (CBS) extrapolations, we have completed an exhaustive search of the DLPNO-CCSD(T)/CBS//ωB97X-D/6-31++G** Gibbs free energy surface for this system. We have used previous work where the weaker formic acid replaces either nitric acid or hydrochloric acid to explore the details of how three acids combine with two bases and a few water molecules to make prenucleation clusters. As clusters grow, stabilizing effects of nitric acid, hydrochloric acid, and formic acid change in unique ways. This research adds to the body of work that illustrates that, depending on the system being studied, the acid/base strength of the monomers, the charge distribution within the clusters, and the detailed hydrogen bond topology have a subtle interplay that determines which cluster is most stable