Applications of the concept of river tracer data similarity

The response of a river to a pollution incident is heavily influenced by the river's flow rate. To capture the full range of this response, tracer experiments are often used. The paper discusses how the concept of similarity of temporal concentration profiles can be used to better exploit the information content of such experiments. Examples are given showing that poor quality tracer data that might be thought to be of little use may yet contain valuable information. Extracting this information has the potential of improving predictions of pollutant travel times, in particular, as well as offering the prospect of improving estimates of flow rates (via dilution gauging) and dispersion coefficients (via several methods).     

共享与交流——GIGA一个中国本土化的可持续设计媒介

设计，必须以一种开放和共享的姿态进行下去，因为它的终极，维系着地球上所有生灵的可持续生存。共享便能节约，GIGA无条件的分享交流精神、真挚的节能环保诚意值得推崇与学习。     

Flow Resistance and Momentum Flux in Compound Open Channels

New formulations are presented for flow resistance and momentum flux in compound open channels. As implemented in the St. Venant equations, these formulations facilitate a physically enhanced approach to evaluating conveyance, roughness, stage-discharge relationship, and unsteady flood routing in compound open channels. An analysis using steady flow data from the well-controlled experiments at the large-scale Flood Channel Facility, HR Wallingford, demonstrates the ability of the present approach to properly resolve the discontinuity of overall roughness across the main-channel bankfull level. Also, the proposed formulations are shown to be conducive to obviating the long-standing computational difficulty in unsteady flood routing due to small flow depths over flat and wide floodplains. The present work should find general applications in one-dimensional computation of river flows.     

Light Emission from Highly Reflective Porous Silicon Multilayer Structures

Porous silicon photoluminescence and electroluminescence can be controlled by periodically modulating the material porosity to form high quality multilayer stacks and microcavities. Important issues not yet fully addressed are (a) the precise role played by this microstructuring, given that the luminescence is distributed throughout the entire structure and that the low porosity layers are highly absorbing at short wavelengths, and (b) whether the quality of such microcavities could be sufficient to support lasing. Using both experimental and theoretical techniques, the emission and reflection properties of different porous silicon single and multilayer structures have been investigated in order to understand further and exploit the nature of light propagation within them.     

Predicting residual stresses in gas turbine components

This article describes work carried out by a major aircraft-engine builder and one of its suppliers to validate the numerical prediction of heat-treatment-induced residual stresses. For verification, the project used a large-scale, nickel-based super alloy forging-, calculated stresses are compared to those measured using a hole-drilling technique. Even though the analyses were conducted by both companies using different software, the results tie closely with the measurements.     

Evidence for genetic anticipation in nodal osteoarthritis

OBJECTIVE: Evidence was sought for genetic anticipation (disease occurring at an earlier age in subsequent generations, with increasing severity) in nodal osteoarthritis (NOA). METHODS: Age at symptom onset and disease severity was compared within 30 parent/offspring pairs with NOA. Correlation between the offspring age of disease onset and the parental age at conception was also assessed. RESULTS: The age at onset of nodal symptoms was earlier in the offspring (43 years (95% confidence intervals (CI) 38 to 47) v 61 (CI 58 to 65); mean difference 18 years (CI 13 to 22): p < 0.001) as was larger joint symptom onset (48 years (CI 41 to 55) v 67 (CI 61 to 73); mean difference 20 years (CI 13 to 27): p < 0.01). A negative correlation existed between age of offspring symptom onset and parental age at conception. Fifteen (50%) offspring had similar or more extensive disease than their parents. CONCLUSIONS: These results suggest genetic anticipation occurs in NOA and if confirmed a search for trinucleotide repeats is warranted.     

An optimal rotator for iterative reconstruction

For implementations of iterative reconstruction algorithms that rotate the image matrix, the characteristics of the rotator may affect the reconstruction quality. Desirable qualities for the rotator include: (1) preservation of global and local image counts; (2) accurate count positioning; (3) a uniform and predictable amount of blurring due to the rotation. A new rotation method for iterative reconstruction is proposed which employs Gaussian interpolation. This method was compared to standard rotation techniques and is shown to be superior to standard techniques when measured by these qualities. The computational cost was demonstrated to be only slightly more than bilinear interpolation