13,570 research outputs found
The Relationship between Principal Leadership Behaviors and School Climate
The No Child Left Behind Act (2001) revised the Elementary and Secondary Education Act of 1965 by making substantial modifications in the major federal programs that support schoolsâ efforts to educate all children (U.S. Department of Education, Office of the Deputy Secretary, 2004). Since the inception of this law, demand for greater accountability for student achievement from politicians and legislators has increased exponentially (Carnoy, Elmore, & Siskin, 2003). Strict accountability measures, developed and implemented with limited if any consent or involvement of educators, were imposed on students, teachers, schools, and school districts (Waite, Boone, & NcGgee, 2001). The increased emphasis on accountability heightened the demands on teachers and administrators more than ever before in the history of education in the United States (Carnoy et al., 2003). As increased accountability became the norm, school leadership became more challenging and demanding in order to achieve the newly stipulated accountability (Salazar, 2008)
Intertemporal and Spatial Location of Disposal Facilities
Optimal capacity and location of a sequence of land.lls are studied, and the interactions between both decisions are pointed out.The decision capacity has some spatial implications, because it a.ects the feasible region for the rest of land.lls, and some temporal implications, because the capacity determines the lifetime of the land.ll and hence the instant of time where next land.lls will need to be constructed.Some general mathematical properties of the solution are provided and interpreted from an economic point of view.The resulting problem turns out to be no convex and therefore it can not be solved by conventional optimization techniques.Some global optimization methods are used to solve the problem in a particular case, in order to illustrate the behavior of the solution depending on parameter values.Landfilling;Optimal Capacity;Optimal Location;Global Optimization
Optimizing stellarators for large flows
Plasma flow is damped in stellarators because they are not intrinsically
ambipolar, unlike tokamaks, in which the flux-surface averaged radial electric
current vanishes for any value of the radial electric field. Only
quasisymmetric stellarators are intrinsically ambipolar, but exact
quasisymmetry is impossible to achieve in non-axisymmetric toroidal
configurations. By calculating the violation of intrinsic ambipolarity due to
deviations from quasisymmetry, one can derive criteria to assess when a
stellarator can be considered quasisymmetric in practice, i.e. when the flow
damping is weak enough. Let us denote by a small parameter that
controls the size of a perturbation to an exactly quasisymmetric magnetic
field. Recently, it has been shown that if the gradient of the perturbation is
sufficiently small, the flux-surface averaged radial electric current scales as
for any value of the collisionality. It was also argued that when
the gradient of the perturbation is large, the quadratic scaling is replaced by
a more unfavorable one. In this paper, perturbations with large gradients are
rigorously treated. In particular, it is proven that for low collisionality a
perturbation with large gradient yields, at best, an deviation
from quasisymmetry. Heuristic estimations in the literature incorrectly
predicted an deviation.Comment: 24 pages, 2 figures. To appear in Plasma Physics and Controlled
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