Flow aeration, cavity processes and energy dissipation on flat and pooled stepped spillways for embankments

The design floods of several reservoirs were recently re-evaluated and the revised spillway outflow could result in dam overtopping with catastrophic consequences for some embankment structures. Herein a physical study was performed on flat and pooled stepped spillways with a slope typical of embankments (theta = 26.6 degrees) and four stepped configurations were tested: a stepped spillway with flat horizontal steps, a pooled stepped spillway, and two stepped spillways with in-line and staggered configurations of flat and pooled steps. The focus of the study was on the flow aeration, air-water flow properties, cavity flow processes, and energy dissipation performances. The results demonstrated the strong aeration of the flow for all configurations. On the in-line and staggered configurations of flat and pooled steps, the flow was highly three-dimensional. The residual head and energy dissipation rates at the stepped chute downstream end were calculated based upon the detailed air-water flow properties. The results showed that the residual energy was the lowest for the flat stepped weir. The data for the stepped spillway configuration with in-line and staggered configurations of flat and pooled steps showed large differences in terms of residual head in the transverse direction. Altogether the present results showed that, on a 26.6 degrees slope stepped chute, the designs with in-line and staggered configurations of flat and pooled steps did not provide any advantageous performances in terms of energy dissipation and flow aeration, but they were affected by three-dimensional patterns leading to some flow concentration

Flow Aeration and Energy Dissipation

Stepped Spillway

Optimism and the Experience of Pain:A Systematic Review

A growing body of literature provides evidence of the health-promoting effects of optimism, including its protective role in acute and chronic pain. Optimists are characterized by positive expectations concerning the future. These positive outcome expectancies lead to more and longer goal-directed efforts and the use of approach coping strategies. No systematic review on the effects of optimism on the experience of pain has so far been conducted. A search in the databases PubMed, Web of Science and PsycInfo, and the scanning of reference lists identified 69 eligible studies. These were categorized according to sample size, participants’ age and sex, design, optimism-pain relation as primary vs. secondary study objective, and level of study/publication quality. Overall percentages of positive, zero, and negative associations between optimism and pain as well as relative frequencies of these associations in the different categories were analyzed. About 70% of the studies showed a positive, i.e., beneficial association between optimism and at least one pain outcome. A larger percentage of beneficial associations was found in studies with experimental designs, in studies with the optimism-pain relation as primary objective, in high-quality studies/publications, and in studies including participants with a higher average age. The review suggests that optimism is associated with less acute and chronic pain, especially since a higher percentage of beneficial associations was found with high study/publication quality and with the primary focus on this relationship. For the moderating role of age, different explanations are proposed. Further research on causal relationships and on optimism-fostering clinical interventions is needed

Evidence for a Ru4+^{4+} Kondo Lattice in LaCu3_3Ru4_4O12_{12}

Rare $d$-electron derived heavy-fermion properties of the solid-solution series LaCu$_3$Ru$_x$Ti$_{4-x}$O$_{12}$ were studied for $1 \leq x \leq 4$ by resistivity, susceptibility, specific-heat measurements, and magnetic-resonance techniques. The pure ruthenate ($x = 4$) is a heavy-fermion metal characterized by a resistivity proportional to $T^2$ at low temperatures $T$. The coherent Kondo lattice formed by the localized Ru 4$d$ electrons is screened by the conduction electrons leading to strongly enhanced effective electron masses. By increasing titanium substitution the Kondo lattice becomes diluted resulting in single-ion Kondo properties like in the paradigm $4f$-based heavy-fermion compound Ce$_x$La$_{1-x}$Cu$_{2.05}$Si$_2$ [M. Ocko {\em et al.}, Phys. Rev. B \textbf{64}, 195106 (2001)]. In LaCu$_3$Ru$_x$Ti$_{4-x}$O$_{12}$ the heavy-fermion behavior finally breaks down on crossing the metal-to-insulator transition close to $x = 2$.Comment: 9 pages, 8 figure

Uncertainty in life cycle costing for long-range infrastructure. Part I: leveling the playing field to address uncertainties

Purpose Life cycle costing (LCC) is a state-of-the-art method to analyze investment decisions in infrastructure projects. However, uncertainties inherent in long-term planning question the credibility of LCC results. Previous research has not systematically linked sources and methods to address this uncertainty. Part I of this series develops a framework to collect and categorize different sources of uncertainty and addressing methods. This systematization is a prerequisite to further analyze the suitability of methods and levels the playing field for part II. Methods Past reviews have dealt with selected issues of uncertainty in LCC. However, none has systematically collected uncertainties and linked methods to address them. No comprehensive categorization has been published to date. Part I addresses these two research gaps by conducting a systematic literature review. In a rigorous four-step approach, we first scrutinized major databases. Second, we performed a practical and methodological screening to identify in total 115 relevant publications, mostly case studies. Third, we applied content analysis using MAXQDA. Fourth, we illustrated results and concluded upon the research gaps. Results and discussion We identified 33 sources of uncertainty and 24 addressing methods. Sources of uncertainties were categorized according to (i) its origin, i.e., parameter, model, and scenario uncertainty and (ii) the nature of uncertainty, i.e., aleatoric or epistemic uncertainty. The methods to address uncertainties were classified into deterministic, probabilistic, possibilistic, and other methods. With regard to sources of uncertainties, lack of data and data quality was analyzed most often. Most uncertainties having been discussed were located in the use stage. With regard to methods, sensitivity analyses were applied most widely, while more complex methods such as Bayesian models were used less frequently. Data availability and the individual expertise of LCC practitioner foremost influence the selection of methods. Conclusions This article complements existing research by providing a thorough systematization of uncertainties in LCC. However, an unambiguous categorization of uncertainties is difficult and overlapping occurs. Such a systemizing approach is nevertheless necessary for further analyses and levels the playing field for readers not yet familiar with the topic. Part I concludes the following: First, an investigation about which methods are best suited to address a certain type of uncertainty is still outstanding. Second, an analysis of types of uncertainty that have been insufficiently addressed in previous LCC cases is still missing. Part II will focus on these research gaps

VADER - A Satellite Mission Concept For High Precision Dark Energy Studies

We present a satellite mission concept to measure the dark energy equation of state parameter w with percent-level precision. The Very Ambitious Dark Energy Research satellite (VADER) is a multi-wavelength survey mission joining X-ray, optical, and IR instruments for a simultaneous spectral coverage from 4microns (0.3eV) to 10keV over a field of view (FoV) of 1 square degree. VADER combines several clean methods for dark energy studies, the baryonic acoustic oscillations in the galaxy and galaxy cluster power spectrum and weak lensing, for a joint analysis over an unrivalled survey volume. The payload consists of two XMM-like X-ray telescopes with an effective area of 2,800cm^2 at 1.5keV and state-of-the-art wide field DEPFET pixel detectors (0.1-10keV) in a curved focal plane configuration to extend the FoV. The X-ray telescopes are complemented by a 1.5m optical/IR telescope with 8 instruments for simultaneous coverage of the same FoV from 0.3 to 4 microns. The 8 dichroic-separated bands (u,g,r,z,J,H,K,L) provide accurate photometric galaxy redshifts, whereas the diffraction-limited resolution of the central z-band allows precise shape measurements for cosmic shear analysis. The 5 year VADER survey will cover a contiguous sky area of 3,500 square degrees to a depth of z~2 and will yield accurate photometric redshifts and multi-wavelength object parameters for about 175,000 galaxy clusters, one billion galaxies, and 5 million AGN. VADER will not only provide unprecedented constraints on the nature of dark energy, but will additionally extend and trigger a multitude of cosmic evolution studies to very large (>10 Gyrs) look-back times.Comment: 14 pages, 7 figures, accepted for publication in the SPIE conference proceeding