Blast overbreak measurement by light sectioning

Summary In this new method for measuring the cross-section of tunnels and other excavations, the opening is outlined by a plane of light projected from a conical mirror. The image is recorded on videotape, enhanced, then measured by microcomputer. The measured profile is compared automatically with the specified profile to give values for overbreak and underbreak.Trials in Mexican tunnels and at an underground mine in Canada have evaluated the technique in relation to traditional mechanical, photographic, and surveying alternatives. Results indicate that the light sectioning method requires less than a minute per profile and no surveying skills. Costs are low, and the measurements are accurate to within a centimetre or two. Using the same photoanalysis technique and software, rock quality can be measured at the same time and place as overbreak, which helps the engineer to decide whether overbreak is caused by geological conditions or by deficiencies in blasting.     

Assessment of various code provisions based on optimum design of steel structures

This paper presents some comparative design results of typical structural systems in accordance with various code provisions, such as UBC and ATC-03 of the U.S. and TJ-11–78 of China. The solution comparisons are based on an optimization scheme for a given set of constraints and objective functions. Three levels of recursive procedures are employed in the algorithm to search for an optimum weight or construction cost including damages. Numerical examples are provided to compare the design results based on the aforementioned code provisions.     

On the original distribution of the asteriods. I.

The depletion of an initially uniform distribution of asteroids extending form Mars to Saturn, caused by the gravitational perturbations of Jupiter and Saturn, is calculated by numerical integration of the asteroid orbits. Almost all (about 85%) the asteroids between Jupiter and Saturn are ejected in the first 6000 years Most of the asteroids between the $\text{2}\text{3}$ Jupiter resonance (4.0 A.U.) and Jupiter are ejected in the first 2400 years with the exception of the stable librators (e.g., the Hilda group). Interior to the $\text{2}\text{3}$ resonance the depletion was small, and interior to the $\text{1}\text{2}$ resonance (3.3 A.U.) no asteroids were ejected in the first 2400 years.     

Tidal torques on infrequently colliding particle disks in binary systems and the truncation of the asteroid belt

We study numerically and analytically the conditions leading to the truncation, at the 2:1 resonance, of a disk of infrequently colliding particles surrounding the primary of a binary system. We focus on systems with small mass ratios, q, such as the Sun-Jupiter system with q = 10^?3. Previous studies showed that if collisions are frequent with respect to the orbital period, truncation 3nly occurs if the Reynolds number is greater than q^?2. This corresponds to particle eccentricity, e, less than of order q for a particle disk of optical depth unity. In thepresent case collisions are less frequent than $\text{q}{}^{\mathrm{<mtext>?2</mtext><mtext>3</mtext>}}$ orbital periods (the period of the forced eccentricity at the 2:1 resonance), and truncation occurs and (Kirkwood) gaps are produced only if e is less than some critical value which we estimate to be of order $\text{q}{}^{\mathrm{<mtext>5</mtext><mtext>9</mtext>}}$, or ～0.02 for the Sun-Jupiter case. We mention several means whereby the eccentricities may have been subsequently increased to their observed values.     

Three Spaces of Spatial Cognition

As we move about and interact in the world, we keep track of different spaces, among them the space of navigation, the space immediately around the body, and the space of the body. We review research showing that these spaces are conceptualized differently. Knowledge of the space of navigation is systematically distorted. For example, people mentally rotate roads and land masses to greater correspondence with global reference frames, they mentally align roads and land masses, they overestimate distances near the viewpoint relative to those far from it. These and other distortions indicate that the space of navigation is schematized to elements and spatial relations relative to reference frames and perspective. The space around the body is organized into a mental framework consisting of extensions of the major axes of the body. Times to report objects around the body suggest that the relative accessibility of the axes depends on their perceptual and functional properties and the relation of the body to the world. Finally, times to verify named or depicted body parts indicate that body schemas depend on perceptual and functional significance. Thus, these spaces (and they are not the only ones important to human interaction) differ from one another and are not conceptualized as Euclidean. Rather they are schematized into elements and spatial relations that reflect perceptual and conceptual significance.     

Downstream trends in sediment size and composition of channel-bed, bar, and bank deposits related to hydrologic and lithologic controls in the Llano River watershed, central Texas, USA

The downstream fining of fluvial sediments is a fundamental tenet of drainage systems and, for decades, has been the subject of considerable research. Most of this research has focused on variability in channel-bed material. Other sedimentological components such as channel bars and banks, however, represent distinctively different processes occurring at various flow magnitudes and durations and thus provide an opportunity to examine a more comprehensive set of controls on the larger fluvial system. This study analyses downstream patterns of sediment size and composition for channel-bed material, bars, and banks in the Llano River watershed (11,568 km²) in central Texas, USA.Fluvial deposits in the study area were characterized through field, laboratory, and statistical analyses and standard sedimentary indices (d₁₆, d₅₀, d₈₄, sorting) were computed. Two hundred thirty-eight sediment samples were collected at 15 sites along the main-stem channel with sampling occurring at the low-flow channel (thalweg), lateral bars, banks, and overbank locations. Channel-bar deposits are characterized by a downstream reduction in particle size, but low-flow-channel deposits have a substantially weaker trend, a discrepancy possibly attributed to uniformity and continuity of hydraulic sorting mechanisms during moderate and high flows. Channel-bar deposits reveal an abrupt downstream reduction in gravel size in the upper watershed, which is attributed to an increase in drainage area. Further, an abrupt gravel-to-sand transition occurs immediately downstream of a distinct lithologic change from mostly carbonate rocks to igneous and metamorphic rocks. The downstream decrease in channel-bar particle size occurs despite an increasingly constricted alluvial valley, commonly associated with greater unit stream power and relatively coarse sediment. Contrasting with channel-bed material, particle size of channel banks increases downstream, which is attributed to the addition of sand-sized sediment from igneous and metamorphic rocks. The consideration of distinctive sedimentological components of a dynamic fluvial system represents a more comprehensive and nuanced study of the topic of downstream sediment trends than prior studies, which is important to a range of engineering, biological, and planning issues at the watershed scale.     

The role of science in setting water resource use limits: case studies from New Zealand

Abstract

Water resource use limits ensure protection of environmental values and define the availability and reliability of water supply for out-of-channel use. We examined how three types of scientific tools (environmental flow setting methods, hydrological analyses for setting total allocations and spatial frameworks) have been used to define limits across jurisdictional regions comprising multiple catchments in New Zealand. We found that recently developed minimum flow and total allocation setting tools are widely used. Spatial frameworks are increasingly used to discriminate and account for variation in environmental characteristics, thereby increasing the specificity of water resource use limits. The uptake of scientific tools has enabled improvements in the clarity of water management objectives and the transparency of limits defined by regional water management plans. We argue that more integrated use of scientific tools could improve the clarity and transparency of regional limits by explicitly demonstrating the trade-off between out-of-channel use and protection of environmental values.

Editor D. Koutsoyiannis; Guest editor M. Acreman

Citation Snelder, T.H., Rouse, H.L., Franklin, P.A., Booker, D.J., Norton, N., and Diettrich, J., 2014. The role of science in setting water resource use limits: case studies from New Zealand. Hydrological Sciences Journal, 59 (3–4), 844–859.     

1DTempPro V2: New Features for Inferring Groundwater/Surface‐Water Exchange

A new version of the computer program 1DTempPro extends the original code to include new capabilities for (1) automated parameter estimation, (2) layer heterogeneity, and (3) time‐varying specific discharge. The code serves as an interface to the U.S. Geological Survey model VS2DH and supports analysis of vertical one‐dimensional temperature profiles under saturated flow conditions to assess groundwater/surface‐water exchange and estimate hydraulic conductivity for cases where hydraulic head is known.