Findings suggest that anger or intrusion likely play a crucial role in the development and maintenance of PTSD (i.e., are more influential within the network than are other symptoms). (PsycINFO Database Record

Thermal fatigue damage may be caused when incompletely mixed hot and cold fluid streams pass over the surface of a component or structure. This kind of thermal fatigue, known as thermal striping, is of particular concern in various types of nuclear reactors and for rapid shut-downs of hot plant. A computer code, known as TBL, is an engineering design tool which has been developed to assess thermal striping damage for fully constrained plates. This model is further developed to account for various plate-constraint conditions. It is compared with two other methods of assessing thermal striping damage. Good agreement is found for the cases when the component is (a) a plate, constrained in various ways and exposed to a sinusoidally varying temperature time striping history and (b) a shroud tube found in the above-core region of a fast reactor pressure vessel and striped with a random temperature time history. NOMENCLATURE a = crack depth A(o, z) = temperature response function B, C = real and imaginary parts of A(o, z) Em, Bb, C, , Cb = membrane and bending components of B and C E = Young's modulus F,, F, = simplifying functions in the stress intensity function g,, gb, gp =membrane, bending and peak temperature to stress conversion factors h = plate thickness H(w, a) = stress intensity response function K(a, t ) = stress intensity factor ml, m2 = polynomials in the Bueckner weight function J,, J2 = simplifying integrals in the stress intensity function K, , K , = maximum and RMS values of the stress intensity factor M(z) = weight function P, Q, R, S = partitions of A(@, z) p = dimensionless through thickness coordinate &(a, a) = power spectral density of the stress intensity factor S,(o) = power spectral density of the surface temperature t = time T = temperature variable x, y = in surface coordinates T,, Tb, Tp = membrane, bending and peak temperature components z = through thickness coordinate a = coefficient of linear expansion A = range v = Poisson's ratio w = temporal angular frequency w,, = upper angular frequency bound in the power spectral density 4, = components of H ( o , a) c , , , cyy = direct stresses in the x and y directions 489 490

When incompletely mixed hot and cold fluid streams pass adjacent to the surface of a component or a structure, they can cause thermal fatigue damage. An analytical model, based on linear elastic fracture mechanics and the frequency response method, is presented for the assessment of thermal fatigue damage. Various shapes of surface temperature-time histories, represented by their power spectral densities, are examined. The model is compared with an alternative method based on the impulse response method and good agreement is found. This kind of thermal fatigue is of particular concern in various types of nuclear reactors and rapid shut-downs of hot plant. The model proposed is intended as an engineering design tool and has been developed as a computer code known as "TBL". NOMENCLATUREF,-F., = Buchalet and Bamford "Influence Functions" F,(fi), F2(P) = dimensionless functions in small crack analysis fo = upper frequency in the power spectral density (PSD) G(w, a), J(w, a) = transfer function components h = plate thickness H(w, a) = stress intensity response function 11, I, =weighted integrals of P and Q respectively over the crack M ( x ) = weight function Kni,, K,,,, K,, = the minimum, maximum and rms values of the stress intensity factor (SIF) m,, rn2 = polynomials in the Bueckner weight function P, Q, R, S = real and imaginary partitions of A(o, x ) p = dimensionless through thickness coordinate S,(o, a) = PSD of the stress intensity factor &(w) = power spectral density of surface temperature signal T, , , , T, , = the maximum and rms values of the surface temperature T(x, t), T, = the temperature function and its time averaged mean t = time x = through-thickness coordinate a = coefficient of linear expansion A = range K = thermal diffusivity I, = reciprocal of attenuation length v = Poisson's ratio u(x, t ) = stress function a, coo = angular frequency and upper bound respectively in the PSD ao, p, SZ = dimensionless factors in small crack analysis

Maintenance represents a significant proportion of the overall operating costs in the mining industry. Despite the large cost of maintenance, management has only given passing attention to the optimization of the maintenance process. The focus has remained on the optimization of mine planning and operations where all the low hanging fruit was picked years ago. Recent initiatives in the field of mobile equipment maintenance have been in the area of remote condition monitoring. In order for an advanced maintenance technology to succeed it must have a strong philosophical basis and the supporting hardware and software infrastructure. A high bandwidth radio network, reliable interfaces, and a real-time maintenance management system will enable remote condition monitoring systems. Explores reliability centered maintenance, remote condition monitoring, and the use of production and maintenance data for real-time interactive maintenance management. Practical implicationsMaintenance related costs account for approximately 30 to 50 percent of direct mining costs. A significant amount of energy has been spent analyzing and optimizing key processes throughout the mine. However, very little attention has been focused towards the optimization of the maintenance process. Maintenance is the largest controllable cost in the mining industry. Significant cost reductions and improvements in equipment reliability and performance will be achieved through the implementation of rationalized proactive maintenance approaches. Condition monitoring has the potential to identify problems prior to failure. Early detection of equipment degradation will enable repairs to be scheduled thereby reducing costs and interruptions to production. The implementation of proactive programs or technologies in a reactive environment involves a significant amount of change to the business practices and processes within the maintenance and operations groups. A strong realtime maintenance management system such as Modular Mining Systems' INTELLIMINE1 will facilitate the implementation of a proactive maintenance program.

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