We investigate the problem of the stability of the number of conjugate or focal points (counted with multiplicity) along a semi-Riemannian geodesic γ. For a Riemannian or a non spacelike Lorentzian geodesic, such number is equal to the intersection number (Maslov index) of a continuous curve with a subvariety of codimension one of the Lagrangian Grassmannian of a symplectic space. Such intersec...

Safeguarding the energy security is an important energy policy goal of every country. Assuring sufficient and reliable resources of energy at affordable prices is the main objective of energy security. Due to such reasons as special geopolitical position, terrorist attacks and other unrest in the Middle East, securing Iran’s energy demand and increasing her natural gas exports have turned into ...

objective: to assess the stability changes as a reflection of early healing around roughened- surface implants in human by resonance frequency analysis (rfa). materials and methods: one hundred and fifty one iti sla implants were placed in either maxilla or mandible of 68 patients. bone type was classified into 4 groups according to lekholm and zarb index. rfa was used for direct implant stabil...

Linearised stability analysis of stationary and periodic solutions of both finite and infinite dimensional dynamical systems is a central issue in many (physical) applications. Such systems usually depend on parameters, so an important question is what happens to stability when the parameters are varied. This implies that one has to study the spectrum of a linear operator and its dependence on ...

OBJECTIVES To compare multidirectional seated postural stability between individuals with spinal cord injury and able-bodied- individuals and to evaluate the impact of abdominal and low back muscle paralysis on multidirectional seated stability. DESIGN Case-control study. PARTICIPANTS Fifteen individuals with complete or incomplete spinal cord injury affecting various vertebral levels parti...

In this study, a Bjerknes stability (BJ) index, proposed by Jin et al. (2006), is adopted to assess the overall stability of El Niño and Southern Oscillation (ENSO) in state-of-the-art coupled models. The twentieth and twenty-first century simulations of 12 coupled models among the coupled model intercomparison project phase 3 models used in the intergovernmental panel on climate change forth a...

In this study, Stability analysis of snow slab which is under detonation has developed in the present model. The model has been studied by using the basic concepts of non-detonation model and concepts of underwater explosions with appropriate modifications to the present studies. The studies have also been extended to account the effect of critical length variations at the time of detonation an...

with increasing the presence of microgrids (mgs) in the power systems, investigating the mg stability during transient faults is necessary. this study investigates the transient stability analysis of a mg supplied by multiple inverter interfaced distributed generations (iidgs) during fault. the transient stability of a mg is highly depends on the iidgs control strategy. a mg, simulated on matla...