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When steam power cycles are modeled, thermodynamic properties as functions of pressure and temperature are required in the critical and supercritical regions (region 3 of IAPWS-IF97). With IAPWS-IF97, such calculations require cumbersome iterative calculations, because temperature and volume are the independent variables in the formulation for this region. In order to reduce the computing time, the International Association for the Properties of Water and Steam (IAPWS) adopted a set of backward equations for volume as a function of pressure and temperature in region 3. The necessary numerical consistency is achieved by dividing the region into 20 subregions, plus auxiliary subregions near the critical point in which the consistency requirements are relaxed due to the singular behavior at the critical point. In this work, we provide complete documentation of these equations, along with a discussion of their numerical consistency and the savings in computer time. The numerical consistency of these equations should be sufficient for most applications in heat-cycle, boiler, and steam-turbine calculations; if even higher consistency is required, the equations may be used to generate guesses for iterative procedures. [DOI: 10.1115/1.3028630]

When steam power cycles are modeled, thermodynamic properties as functions of enthalpy and entropy are required in the critical and supercritical regions (region 3 of IAPWS-IF97). With IAPWS-IF97, these calculations require cumbersome two-dimensional literation of temperature T and specific volume v from specific enthalpy h and specific entropy s. While these calculations are not frequently required, the computing time can be significant. Therefore, the International Association for the Properties of Water and Steam (IAPWS) adopted backward equations for p(h,s) in region 3. For calculating properties as a function of h and s in the part of the two-phase region that is important for steam-turbine calculations, a backward equation [T.sub.sat](h,s) is provided. In order to avoid time-consuming iteration in determining the region for given values of h and s, equations for the region boundaries were developed. The numerical consistency of the equations documented here is sufficient for most applications in heat-cycle, boiler, and steam-turbine calculations. [DOI: 10.1115/1.2719267]

In modeling advanced steam power cycles, thermodynamic properties as functions of pressure and enthalpy (p,h) or pressure and entropy (p,s) are required in the critical and supercritical regions (region 3 of IAPWS-IF97). With IAPWS-IF97, these calculations require cumbersome two-dimensional iteration of temperature T and specific volume u from (p,h) or (p,s). While these calculations in region 3 are not frequently required, the computing time can be significant. Therefore, the International Association for the Properties of Water and Steam (IAPWS) adopted backward equations for T(p,h), v(p,h), T(p,s), and u(p ,s) in region 3, along with boundary equations for the saturation pressure as a function of enthalpy, [P.sub.3sat](h), and of entropy, [P.sub.3sa]t(S). Using the new equations, two-dimensional iteration can be avoided. The numerical consistency of temperature and specific volume obtained in this way is sufficient for most uses. This paper summarizes the need and the requirements for these equations and gives complete numerical information. In addition, numerical consistency and computational speed are discussed. [DOI: 10.1115/1.2181598]

Objectives: To investigate the clinical and MRI features of brain stem and cerebellar lesions in Japanese patients with multiple sclerosis.Methods: A retrospective study of 66 consecutive Japanese patients with multiple sclerosis (42 women and 24 men) was done by reviewing the medical records and MRI films. Forty nine patients were diagnosed as having clinically definite multiple sclerosis and 17 patients as having clinically probable multiple sclerosis according to Poser's criteria. Prevalence rates of each brain stem and cerebellar manifestation and frequency and distribution of MRI lesions in these patients were studied.Results: Forty three patients (65%) had one or more infratentorial manifestations. Cranial nerves were clinically involved in 28 patients (42%), and most of the lesions were identified by MRI. Among them, manifestations of facial, trigeminal, and abducens nerves were relatively common. Cerebellar ataxia was found in 20 patients (30%). The MRI study showed that the lesions responsible for ataxia in these patients were mainly found in the cerebellar peduncles, but cerebellar hemispheric lesions were detected in only four patients (6.4%).Conclusion: The low frequency (6.4%) of the cerebellar MRI lesions in these patients is in sharp contrast with the figures reported for white patients with multiple sclerosis (50%-90%). Racial and genetic differences may have an influence on the susceptibility of each part of the CNS to demyelination in multiple sclerosis. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the variability of foot clearance during stair descent in young and older adults under varied illuminance conditions. 12 young adults and 10 older adults completed 5 descents of a 7 stair experimental staircase under 2 illuminance conditions (3 lux and 300 lux). The minimum clearances of the left shoe sole over the edge and tread of steps 1, 3, 5 and 7 were calculated for each trial. There were 2 trips and 1 slip during the dark condition in the older subjects. The older adults had significantly higher coefficients of variation of foot clearance (35.3%) compared to the young adults (25.5%) which resulted from a higher standard deviation and lower mean clearance in the older subjects. These results suggest that increased variability in the clearance of the foot over the stair may play a role in stair accidents in the elderly.