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991.
Sustainable management of an alpine national park: handling the two-edged effect of tourism 总被引:1,自引:0,他引:1
Doris A. Behrens Birgit Bednar-Friedl Michael Getzner 《Central European Journal of Operations Research》2009,17(3):233-253
Attracting visitors to an alpine national park can open up additional sources of funding for species conservation. However,
tourism also brings ecologically negative impacts to the park and, in particular, to endangered species. In this paper, we
discuss the handling of this two-edged effect of nature-based tourism within the context of a national park’s management decision.
We develop a stylized model which frames the interaction of a representative largely unknown species, its habitat, and park
visitors in an alpine ecosystem. In applying this to the protection of a rock partridge population in the Hohe Tauern National
Park (Austria), we illustrate that a combined visitor and species protection policy can maximize steady state net benefits
from tourism and conservation, while ensuring that the endangered species reaches its conservation target in the long run.
Thus, even for a small, largely unknown species such as the rock partridge, and not only for popular species like the golden
eagle, it is possible to endogenously generate a conservation budget by attracting visitors. 相似文献
992.
I. L. Solov’ev 《International Applied Mechanics》2006,42(7):818-824
The critical states in simple and compound rotation of thin cylindrical shells elastically coupled with a platform are modeled
theoretically. The technique developed has been implemented in a software system intended to analyze the mechanical phenomena
associated with the critical states and to establish general conditions for such phenomena to occur. The results obtained
may be used to model the dynamic behavior of turbine rotors in aircraft and ship engines
__________
Translated from Prikladnaya Mekhanika, Vol. 42, No. 7, pp. 107–115, July 2006. 相似文献
993.
We describe the Galois closure of the Garcia–Stichtenoth tower and prove that it is optimal. 相似文献
994.
Daniel Wachsmuth 《Journal of Mathematical Analysis and Applications》2006,319(1):228-247
In this article sufficient optimality conditions are established for optimal control problems with pointwise convex control constraints. Here, the control is a function with values in Rn. The constraint is of the form u(x)∈U(x), where U is a set-valued mapping that is assumed to be measurable with convex and closed images. The second-order condition requires coercivity of the Lagrange function on a suitable subspace, which excludes strongly active constraints, together with first-order necessary conditions. It ensures local optimality of a reference function in an L∞-neighborhood. The analysis is done for a model problem namely the optimal distributed control of the instationary Navier-Stokes equations. 相似文献
995.
The quadratic rotational constants A and B and torsional barrier V3, distortion parameters DJ, DK, and DJK, torsional distortion parameters Dm, DJm, and DKm, and barrier-dependence parameters F3J, F3K, and F3m have been determined for CH3CH3, CH3CD3, CD3CD3, and CH3SiH3 from the results of ab initio calculations done at the CCSD(T) level. Calculated values for the first six parameters are consistently within about 1% of experimental values, while the relative errors for Dm, DKm, F3J, and F3K are generally less than 20%. Calculation of the parameters DJm and DsJ is found to be more problematic, even with the application of vibrational averaging in the harmonic oscillator approximation. There is evidence that this is due to the influence of vibrational contact transformations in the experimental values. 相似文献
996.
This paper deals with the valuation of the Russian option with finite time horizon in the framework of the Black–Scholes–Merton model. On the basis of the PDE approach to a parabolic free boundary problem, we derive Laplace transforms of the option value, the early exercise boundary and some hedging parameters. Using Abelian theorems of Laplace transforms, we characterize the early exercise boundary at a time to close to expiration as well as the well-known perpetual case in a unified way. Furthermore, we obtain a symmetric relation in the perpetual early exercise boundary. Combining the Gaver–Stehfest inversion method and the Newton method, we develop a fast algorithm for computing both the option value and the early exercise boundary in the finite time horizon. 相似文献
997.
Ben Brüggemann Tnu Pullerits Volkhard May 《Journal of photochemistry and photobiology. A, Chemistry》2007,190(2-3):372-377
Femtosecond laser pulse control of exciton dynamics in a biological chromophore complex is studied theoretically. The computations use the optimal control theory specified to open quantum systems and formulated in the framework of the rotating wave approximation. Based on the laser pulse induced formation of an excitonic wave packet the possibility to localize excitation energy at a certain chromophore within a photosynthetic antenna system (FMO complex of green bacteria) is investigated. Details of exciton dynamics driven by a polarization shaped pulse are discussed. 相似文献
998.
The changes of decay rates of radionuclide 111In(electron capture) and 32P(β decay) induced by exter-nal mechanic motion are studied. The results indicate that,in the external circular rotation in clockwise and anticlockwise centrifuge on Northern Hemisphere(radius 8 cm,2000 r/min) ,the half life of 111In compared with the referred(2.83 d) is decreased at 2.83% and increased at 1.77%,respectively;the half life of 32P compared with the referred(14.29 d) is decreased at 3.78% and increased at 1.75%,respec-tively. When the clockwise and anticlockwise rotations increase to 4000 r/min,the half life of 111In is decreased at 11.31% and increased at 6.36%,respectively;the half life of 32P is decreased at 10.08% and increased at 4.34%,respectively. When the circular rotation is removed,the decay rates of 111In and 32P return back to the referred,respectively. It is found that the external circular rotations in clockwise and anticlockwise centrifuge selectively increased and decreased the decay rates of 111In and 32P,respec-tively,and the effects are strongly dependent on the strength of circular rotation. It is suggested that these effects may be caused by the chiral interaction. 相似文献
999.
Using a semi-discrete model that describes the heat transfer of a continuous casting process of steel, this paper is addressed
to an optimal control problem of the continuous casting process in the secondary cooling zone with water spray control. The
approach is based on the Hamilton–Jacobi–Bellman equation satisfied by the value function. It is shown that the value function
is the viscosity solution of the Hamilton–Jacobi–Bellman equation. The optimal feedback control is found numerically by solving
the associated Hamilton–Jacobi–Bellman equation through a designed finite difference scheme. The validity of the optimality
of the obtained control is experimented numerically through comparisons with different admissible controls. Detailed study
of a low-carbon billet caster is presented. 相似文献
1000.
Multiple pulses with broadband spectrum generation are experimentally obtained in passively mode-locked erbium-doped fiber ring lasers based on nonlinear polarization rotation, which is achieved by incorporating a length of highly nonlinear dispersion-shifted fiber in the laser cavity. The temporal and spectral dynamic behaviors of multipulse bunching states are demonstrated. The maximum spectral width and flatness are attained when the continuous-wave component is suppressed under appropriate polarization states and pump powers. 相似文献