SIMULATION METHODS APPLICATION FOR LPG DELIVERIES PLANNING AND SCHEDULING TO THE NETWORK OF STATIONS UNDER DEMAND UNCERTAINTY

In our paper we considered the problem of demand uncertainty and its influence on planning and scheduling of LPG deliveries. The experience of specialized transportation company in charge of LPG deliveries for the domestic supplier network under VMI approach was analyzed. High variability of distribution parameters and frequent orders modifications were observed while small stations tanks capacities comparing to high daily LPG sales volumes were considered. The combined use of simulation and optimization methods was proposed for the case of LPG distribution to the petrol stations network. The demand uncertainty at customers' stations was considered. Simulation models were assumed to be efficient for dynamic and robust delivery plans of LPG distribution. The results of computational experiments were presented for different values of coefficient of variation

One-dimensional quasi-relativistic particle in the box

Two-term Weyl-type asymptotic law for the eigenvalues of one-dimensional quasi-relativistic Hamiltonian (-h^2 c^2 d^2/dx^2 + m^2 c^4)^(1/2) + V_well(x) (the Klein-Gordon square-root operator with electrostatic potential) with the infinite square well potential V_well(x) is given: the n-th eigenvalue is equal to (n pi/2 - pi/8) h c/a + O(1/n), where 2a is the width of the potential well. Simplicity of eigenvalues is proved. Some L^2 and L^infinity properties of eigenfunctions are also studied. Eigenvalues represent energies of a `massive particle in the box' quasi-relativistic model.Comment: 40 pages, 4 figures; minor correction

How are "teaching the teachers" courses in evidence based medicine evaluated? A systematic review

Background Teaching of evidence-based medicine (EBM) has become widespread in medical education. Teaching the teachers (TTT) courses address the increased teaching demand and the need to improve effectiveness of EBM teaching. We conducted a systematic review of assessment tools for EBM TTT courses. To summarise and appraise existing assessment methods for teaching the teachers courses in EBM by a systematic review. Methods We searched PubMed, BioMed, EmBase, Cochrane and Eric databases without language restrictions and included articles that assessed its participants. Study selection and data extraction were conducted independently by two reviewers. Results Of 1230 potentially relevant studies, five papers met the selection criteria. There were no specific assessment tools for evaluating effectiveness of EBM TTT courses. Some of the material available might be useful in initiating the development of such an assessment tool. Conclusion There is a need for the development of educationally sound assessment tools for teaching the teachers courses in EBM, without which it would be impossible to ascertain if such courses have the desired effect

Simulation Methods Application for LPG Deliveries Planning and Scheduling to the Network of Stations Under Demand Uncertainty

In our paper we considered the problem of demand uncertainty and its influence on planning and scheduling of LPG deliveries. The experience of specialized transportation company in charge of LPG deliveries for the domestic supplier network under VMI approach was analyzed. High variability of distribution parameters and frequent orders modifications were observed while small stations tanks capacities comparing to high daily LPG sales volumes were considered. The combined use of simulation and optimization methods was proposed for the case of LPG distribution to the petrol stations network. The demand uncertainty at customers' stations was considered. Simulation models were assumed to be efficient for dynamic and robust delivery plans of LPG distribution. The results of computational experiments were presented for different values of coefficient of variation

Echo-guided left ventricular assist device speed optimisation for exercise maximisation

OBJECTIVE: Current generation left ventricular assist devices (LVADs) operate with a fixed rotation speed and no automated speed adjustment function. This study evaluates the concept of physiological pump speed optimisation based on aortic valve opening (AVO) imaging during a cardiopulmonary exercise test (CPET). METHODS: This prospective crossover study (NCT05063006) enrolled patients with implanted third-generation LVADs with hydrodynamic bearing. After resting speed optimisation, patients were randomised to a fixed-modified speed or modified-fixed speed CPET sequence. Fixed speed CPET maintained baseline pump settings. During the modified speed CPET, the LVAD speed was continuously altered to preserve periodic AVO. RESULTS: We included 22 patients, the mean age was 58.4±7 years, 4.5% were women and 54.5% had ischaemic cardiomyopathy. Exertional AVO assessment was feasible in all subjects. Maintaining periodic AVO allowed to safely raise the pump speed from 2900 (IQR 2640–3000) to 3440 revolutions per minute (RPM) (IQR 3100–3700; p<0.001). As a result, peak oxygen consumption increased from 11.1±2.4 to 12.8±2.8 mL/kg/min (p<0.001) and maximum workload from 1.1 (IQR 0.9–1.5) to 1.2 W/kg (IQR 0.9–1.7; p=0.028). The Borg scale exertion level decreased from 15.2±1.5 to 13.5±1.2 (p=0.005). CONCLUSIONS: Transthoracic AVO imaging is possible during CPETs in patients with LVAD. Dynamic echo-guided pump speed adjustment based on the AVO improves exercise tolerance and augments peak oxygen consumption and maximum workload