Robustness and Control of a Magnetically Levitated Transportation System

Electromagnetic suspension of Magnetic Levitation Vehicles (Maglev) has been studied for many years as an alternative to wheel-on rail transportation systems. In this work, design and implementation of control systems for a Maglev laboratory experiment and a Maglev vehicle under development at Old Dominion University are described. Both plants are modeled and simulated with consideration of issues associated with system non-linearity, structural flexibility and electromagnetic force modeling. Discussion concerning different control strategies, namely centralized and decentralized approaches are compared and contrasted in this work. Different types of electromagnetic non-linearities are considered and described to establish a convenient method for modeling such a system. It is shown how a Finite Element structural model can be incorporated into the system to obtain transfer function notation. Influence of the dynamic interaction between the Maglev track and the Maglev vehicle is discussed and supported by both analytical results and theoretical examples. Finally, several control laws designed to obtain stable and robust levitation are explored in detail

Perinatal outcome according to chorionicity in twins — a Polish multicenter study

Objectives: The aim of the study was to analyze the perinatal outcome of twin gestations and estimate the influence of chorionicity on the outcome in a large cohort of twin pregnancies in Poland. Material and methods: A retrospective analysis of 465 twin deliveries in 6 Polish centers in 2012 was conducted. Baseline characteristics, the course of pregnancy and labor, as well as the neonatal outcome were analyzed in the study group and according to chorionicity. Results: A total of 356 twin pregnancies were dichorionic (DC group) (76.6%), and 109 were monochorionic (MC group) (23.4%). There were no differences in the occurrence of pregnancy complications according to chorionicity, except for IUGR of at least one fetus (MC 43.1% vs. DC 34.6%; p = 0.003). 66.5% of the women delivered preterm, significantly more in the MC group (78% vs. 62.9%; p = 0.004). Cesarean delivery was performed in 432 patients (92.9%). Mean neonatal birthweight was statistically lower in the MC group (2074 g vs. 2370 g; p < 0.001). Perinatal mortality of at least one twin was 4.3% (2.8% in the DC group vs. 9.2% in the MC group; p = 0.004). Neonatal complications, including NICU admission, respiratory disorders, and infections requiring antibiotic therapy, were significantly more often observed among the MC twins. Conclusions: The overall perinatal outcome in the presented subpopulation of Polish twins and its dependence on cho­rionicity is similar to the reports in the literature. Nevertheless, the rates of preterm and cesarean deliveries remain higher. It seems that proper counselling of pregnant women and education of obstetricians may result in reduction of these rates

Zaopatrzenie krwotoku poporodowego szwami kompresyjnymi. Globalny wpływ na śmiertelność kobiet

Artykuł przedstawia siłę empirycznego podejścia dotyczącego postępowania w krwotoku poporodowym (PPH) z użyciem szwów kompresyjnych oraz podejmuje analizę piśmiennictwa postępowania w krwotoku poporodowym na świecie w ciągu ostatnich 20 lat. Szwy kompresyjne macicy według B-Lyncha są używane w ośrodkach na całym świecie i są najpopularniejszym i najbardziej skutecznym sposobem postępowania w PPH. Dostępne dane sugerują, że ponad 2 000 000 kobiet odniosło korzyści z zastosowania szwów B-Lyncha w ciągu 20 lat od ich wprowadzenia