[en] In many underground nuclear waste repository systems, such as at Yucca Mountain, water flow rate and amount of water seepage into the waste emplacement drifts are mainly determined by hydrological properties of fracture network in the surrounding rock mass. Natural fracture network system is not easy to describe, especially with respect to its connectivity which is critically important for simulating the water flow field. In this paper, we introduced a new method for fracture network description and prediction, termed multi-point-statistics (MPS). The process of the MPS method is to record multiple-point statistics concerning the connectivity patterns of a fracture network from a known fracture map, and to reproduce multiple-scale training fracture patterns in a stochastic manner, implicitly and directly. It is applied to fracture data to study flow field behavior at the Yucca Mountain waste repository system. First, the MPS method is used to create a fracture network with an original fracture training image from Yucca Mountain dataset. After we adopt a harmonic and arithmetic average method to upscale the permeability to a coarse grid, THM simulation is carried out to study near-field water flow in the surrounding waste emplacement drifts. Our study shows that connectivity or patterns of fracture networks can be grasped and reconstructed by MPS methods. In theory, it will lead to better prediction of fracture system characteristics and flow behavior. Meanwhile, we can obtain variance from flow field, which gives us a way to quantify model uncertainty even in complicated coupled THM simulations. It indicates that MPS can potentially characterize and reconstruct natural fracture networks in a fractured rock mass with advantages of quantifying connectivity of fracture system and its simulation uncertainty simultaneously.

[en] The soliton solutions of the nonlinear partial differential equation iq_t + α(t)q_chichi + absolute value of q ²q - iβ(t)q_chichichi = 0 are considered. This equation governs a wide variety of nonlinear waves in nonuniform plasmas, e.f., ion acoustic waves or Trivelpiece-Gould modes,as well as waves on an axially-nonuniform optical fiber. In many applications, the variable t is actually distance, whereas chi is time. The terms involving α and β are due to dispersion and higher-order dispersion, respectively. When β = 0 and α is constant, the equation becomes the nonlinear Schrodinger equation for which soliton solutions are well known. Two special cases are considered. The first is that in which the higher order dispersive term is negligible, β = 0. Grimshaw has given an exact soliton solution in the special case in which α -- exp(t/t_o), and has found the lowest-order perturbative solution based on the assumption that α(t) varies slowly. The authors carry out the perturbative solution to higher order to find how the nonuniformity of the medium modifies certain important soliton properties such as shape, amplitude, width, and phase shift. The second case is that in which α = const and the higher-order dispersive term β is a small perturbation. They carry out a perturbative expansion to determine the modification of the soliton shape, speed, and phase shift as well as the nonlinear frequency shift and radiation due to the higher-order dispersive term

[en] The use of a direct perturbation theory in which u is expanded in powers of the perturbation parameter var-epsilon, yields the following soliton modifications through order var-epsilon: the soliton retains its hyperbolic secant shape, but its velocity is increased and it experiences a negative wavenumber shift. No radiation is predicted by this direct perturbation theory. However, numerical integration shows that the soliton does radiate

[en] The infrared bolometric luminosity of the extended emission from the L1551 flow exceeds 20 solar luminosities. Ultraviolet radiation from the shock associated with the flow appears to heat the dust requiring shock temperatures from 10,000 to 90,000 K in L1551, velocities of approximately 50 km/s near the end of the flow, and a minimum mechanical luminosity of approximately 40 solar luminosities. The total energy requirement of the infrared emission over a 10,000 year lifetime is 10 to the 46th to 47th ergs, two orders of magnitude higher than previous estimates for L1551. Infrared radiation offers a method of probing interstellar shocks, by sampling the untraviolet halo surrounding the shock. At least one current model for bipolar flows is capable of meeting the energetic requirements

[en] Observations made with a resolution of 36 arcmin with the DRAO 26-m radio telescope of H I towards Lambda Orionis and its surrounding H II region S264 and large (diameter about 8 deg) dust ring are presented. A clear deficiency in the integrated H I emission corresponds to the interior of the dust ring. The amount of the missing H I is about 6000 solar masses. This amount of mass is in good agreement with the amount of ionized material seen in the Lambda Orionis H II region. Although there are several H I clumps around the periphery of the dust ring, some of which correspond to CO peaks, it is clear that any H I shell corresponding to the ring is far from complete. The most striking H I emission feature associated with the dust ring is an arc in the west with a velocity near 0 km/s, which corresponds closely to the brightest IR dust emission and to the most strongly defined boundary of the H II region S264. 19 refs

[en] Some properties of small-amplitude ion-acoustic solitons in a plasma consisting of nondrifting electrons and drifting ions are investigated. Electron inertia effects are shown to be considerably more important than relativistic effects. It is also shown that ion-acoustic soliton solutions exist only if the ion drift velocity is less than the electron thermal velocity

[en] The properties of arbitrary-amplitude solitary waves in a plasma consisting of drifting ions and nondrifting electrons are investigated. The conditions for the existence of solitary-wave solutions are determined. It is shown that electron inertia has the significant effect of restricting the regime of solitary waves to ion drift velocities that are less than the electron thermal speed. Because of this restriction relativistic effects are small

[en] The soliton modifications resulting from the addition of a small third derivative term, due to higher-order dispersion, to the nonlinear Schroedinger equation are investigated. Based on direct perturbation theory, it is shown that through first order, the soliton phase and velocity are modified, but the shape, amplitude, and width are unchanged. The radiation stimulated by the third derivative term, which is not predicted by the perturbation theory, is also derived. The expression obtained confirms the result of Wai (Ph.D. thesis, University of Maryland, 1988), which was obtained by a different method. The rate of change of the soliton amplitude due to this radiation, which emerges in front of the soliton, is calculated. The nonlinear term that drives the radiation is shown to grow to a value that is much larger than the unperturbed value

[en] The effects of a cold ion beam on an ion-acoustic solitary wave whose potential is large enough to reflect the ion beam are studied in the regime in which the solitary-wave response to the beam is adiabatic. It is shown that the solitary wave can be amplified by a large factor, and that it is accelerated until its velocity equals the beam velocity

[en] Other authors have considered ion acoustic solitary waves and double layers in a weakly-relativistic plasma. These analyses were based on a plasma model in which the ions are considered to be cold and the electrons are isothermal. The ions are assumed to have a streaming velocity, and relativistic effects enter through the relativistic variation of ion mass. It is shown that an exact pseudopotential can be derived and that the equation governing the solitary wave is of the same form as that of a particle moving in the pseudopotential. From the properties of the pseudopotential, the authors obtain the conditions for the existence of solitary waves in a relativistic plasma. Relativistic effects on the amplitude, width, and velocity of the solitary wave are also determined