Horizontal Directional Drilling: Profile of an Emerging Industry

Perhaps the fastest growing segment in the underground trenchless construction industry is horizontal directional drilling (HDD). Currently, in North America alone, there are 17 manufacturers of HDD rigs and accessories and thousands of horizontal drilling rigs that are owned and operated by several hundred dedicated HDD contractors as well as utility companies and large pipeline outfits. Applications of HDD span across the civil engineering spectrum from mineral and oil exploration to the installation of telecommunication cables. An industry survey was conducted to gain a better understanding of this multibillion dollar industry, which is relatively unfamiliar to many in the construction sector. This paper presents the results obtained from analyzing 49 survey responses from HDD contractors in the United States and Canada. Topics investigated include company profile (e.g., annual volume, areas of activities); type of projects performed (e.g., applications, value, duration, type of product installed), and bidding and estimating practices (e.g., productivity values in various formations, cost of installation), Current and future trends in the industry are identified and discussed.     

Lattices which are good for (almost) everything

We define an ensemble of lattices, and show that for asymptotically high dimension most of its members are simultaneously good as sphere packings, sphere coverings, additive white Gaussian noise (AWGN) channel codes and mean-squared error (MSE) quantization codes. These lattices are generated by applying Construction A to a random linear code over a prime field of growing size, i.e., by "lifting" the code to /spl Ropf//sup n/.     

Lead concentrations and isotopic ratios in the sediments of the Sea of Galilee

The isotopic composition and concentrations of Pb in the sediments of the Sea of Galilee (Lake Kinneret) were measured. The studied sediments have been deposited in the lake since the early 1900s (ca. 1920), hence Pb data record the transition from a period when the lake vicinity was sparsely populated to the present (approximately 100,000 people living in the area around the lake). In general, there is either a constant or a relatively slow increase in Pb concentrations from 40 cm depth (3.5-4.4 microg/g; ca. 1920) to 17 +/- 2 cm below the sediment-water interface (3.7-7.2 microg/g;), which was deposited in the mid-1960s. From 17 +/- 2 cm below the surface, there is a much faster increase up to 7 +/- 2 cm below the surface (from 6.5 to 11.5 microg/g; 1982-1983), and from 7 +/- 2 cm there is a gradual decrease in Pb concentrations toward the sediment-water interface. At station G, near the outlet of the Jordan River, Pb concentrations drop between 29 and 25 cm below the surface, probably reflecting changes in the particulate load of the Jordan River due to the drying out of the Hula Swamp in the early 1950s. 206Pb/207Pb values in all the stations record most of the shifts displayed by Pb concentrations in the sediment. The estimated value of total Pb deposited annually in the lake sediment in the early 1990s is very close to the value obtained from measurements of Pb fluxes to the lake from eolian and fluvial sources. On the basis of the linear relationship between 206Pb/207Pb (or 208Pb/207Pb) and 1/[Pb], we argue that two end-members contribute most of the Pb to the lake sediments. Sources of Pb to the lake include (i) the weathering of basalt from the eastern Galilee and the Golan Heights contributing 2.6 +/- 0.5 microg/g Pb to the sediment and (ii) anthropogenic Pb that is affecting both surface and deep (from 30 to 40 cm) lake sediments. At station S, a third source, Pb released from soils developed on carbonates, should be considered as well.     

The hardness of approximation: Gap location

We refine the complexity analysis of approximation problems by relating it to a new parameter calledgap location. Many of the results obtained so far for approximations yield satisfactory analysis with respect to this refined parameter, but some known results (e.g.,max-k-colorability, max 3-dimensional matching andmax not-all-equal 3sat) fall short of doing so. As a second contribution, our work fills the gap in these cases by presenting new reductions.Next, we present definitions and hardness results of new approximation versions of some NP-complete optimization problems. The problems we treat arevertex cover (for which we define a different optimization problem from the one treated in Papadimitriou & Yannakakis 1991),k-edge coloring, andset splitting.     

Speciation of gas-phase and fine particle emissions from burning of foliar fuels

Fine particle matter with aerodynamic diameter <2.5 microm (PM2.5) and gas-phase emissions from open burning of six fine (foliar) fuels common to fire-prone U.S. ecosystems are investigated. PM2.5 distribution is unimodal within the 10-450 nm range, indicative of an accumulation mode. Smoldering relative to flaming combustion shows smaller particle number density per unit time and median size. Over 100 individual organic compounds in the primarily carbonaceous (>70% by mass) PM2.5 are chemically speciated by gas chromatography/mass spectrometry. Expressed as a percent of PM2.5 mass, emission ranges by organic compound class are as follows: n-alkane (0.1-2%), polycyclic aromatic hydrocarbon (PAH) (0.02-0.2%), n-alkanoic acid (1-3%), n-alkanedioic acid (0.06-0.3%), n-alkenoic acid (0.3-3%), resin acid (0.5-6%), triterpenoid (0.2-0.5%), methoxyphenol (0.5-3%), and phytosterol (0.2-0.6%). A molecular tracer of biomass combustion, the sugar levoglucosan is abundant and constitutes a remarkably narrow PM2.5 mass range (2.8-3.6%). Organic chemical signatures in PM2.5 from open combustion of fine fuels differ with those of residential wood combustion and other related sources, making them functional for source-receptor modeling of PM. Inorganic matter [PM2.5 - (organic compounds + elemental carbon)] on average is estimated to make up 8% of the PM2.5. Wavelength dispersive X-ray fluorescence spectroscopy and ion chromatography identify 3% of PM2.5 as elements and water-soluble ions, respectively. Compared with residential wood burning, the PM2.5 of fine fuel combustion is nitrate enriched but shows lower potassium levels. Gas-phase C2-C13 hydrocarbon and C2-C9 carbonyl emissions are speciated by respective EPA Methods T0-15 and T0-11A. They comprise mainly low molecular weight C2-C3 compounds and hazardous air pollutants (48 wt % of total quantified volatile organic carbon).