Cumulative Time Statistics of Surface-Point Rainfall Rates

Statistics on rainfall rates near and above the earth's surface are needed in order to estimate the percentage of time of absorption, or scattering of radio waves that affect radio system design and electrospace management. The most useful averaging time for computing such rates is on the order of 1 min or less. This paper extrapolates excessive short-duration precipitation data to provide such statistics from data routinely reported by the National Weather Service. For the 8766 h in an average year, and for a median or random location in any part of the world, the model described here estimates the fraction of time during whicht-minute average rainfall rates exceed any given value.     

On Surface Losses in Direct Metal Laser Sintering Printed Millimeter and Submillimeter Waveguides

Different lengths of WR3 (220–330 GHz) and WR10 (75–110 GHz) waveguides are fabricated through direct metal laser sintering (DMLS). The losses in these waveguides are measured and modelled using the Huray surface roughness model. The losses in WR3 are around 0.3 dB/mm and in WR10 0.05 dB/mm. The Huray equation model is accounting relatively good for the attenuation in the WR10 waveguide but deviates more in the WR3 waveguide. The model is compared to finite element simulations of the losses assuming an approximate surface structure similar to the resulting one from the DMLS process.     

Radiological and legal aspects of energy production by burning peat

Peat burning is planned as one of the future sources for heat production in Sweden. At the end of 1983, results of some investigations on peat ashes indicated enhanced uranium contents. Recent measurements on peat areas have shown external gamma radiation dose rates up to 10 microGy/h and samples of dried peat have shown a radium content up to 3.3·10⁵ Bq/kg. In order to estimate the radiological impact of the use of peat as an energy source, the National Institute of Radiation Protection in Sweden has initiated some research projects. Some preliminary results will be discussed against the background of possible need for limits and protection measures. In some cases the high uranium content of the ash makes it necessary, with present regulations, to have special licenses. Both the radiological impact and legal aspects will be discussed.     

Load-carrying capacity evaluation of coating/substrate systems for hydrogen-free and hydrogenated diamond-like carbon films

Diamond-like carbon (DLC) coatings have shown excellent tribological properties in laboratory tests. The coatings have also been introduced to several practical applications. However, the functional reliability of the coatings is often weakened by adhesion and load-carrying capacity related problems. In this study the load-carrying capacity of the coating/substrate system has been evaluated. The DLC coatings were deposited on stainless steel, alumina and cemented carbide with two different deposition techniques: the tetrahedral amorphous carbon (ta-C) coatings were deposited by a pulsed vacuum arc discharge deposition method and the hydrogenated carbon (a-C:H) films by radio frequency (r.f.) plasma deposition method. The load-carrying capacity of the coated systems was evaluated using a scratch test, Rockwell C-indentation test and ball-on-disc test. The effect of substrate material, substrate hardness, coating type and coating thickness was studied. An increase in substrate hardness increased the load-carrying capacity for the coated systems, as expected. The two coating types exhibited different performance under load due to their different physical and mechanical properties. For the load-carrying capacity evaluations the ball-on-disc configuration was found to be most suitable. This revised version was published online in July 2006 with corrections to the Cover Date.     

Surfactants in heterophase polymerization: A study of film formation using force microscopy

Film formation of three different latices was studied using atomic force microscopy. The latices were made from a mixture of butyl acrylate, styrene, and acrylic acid using either a polymerizable or an unreactive anionic surfactant as an emulsifier. Sodium 11-crotonoyloxyundecan-1-ylsulfate and sodium 3-(sulfopropyl)tetradecylmaleate were used as a reactive surfactant and the unreactive surfactant was sodium dodecylsulfate (SDS). The conventional surfactant was found to migrate to the surface of the latex film to a much greater extent than did the reactive surfactants; however, also, the latter were incompletely anchored to the particle. The maleate surfactant was bound to a higher degree than was the crotonate, a finding which is in line with the relative reactivities of the two surfactants. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 187–198, 1997     

Reactive surfactants in heterophase polymerization. VI. Synthesis and screening of polymerizable surfactants (surfmers) with varying reactivity in high solids styrene—butyl acrylate—acrylic acid emulsion polymerization

Several polymerizable surfactants (surfmers) have been used in the semi-continuous emulsion copolymerization of styrene, butyl acrylate, and acrylic acid. Three of the (anionic) surfmers (sodium 11-crotonoyl undecan-1-yl sulfate, sodium 11-methacryloyl undecan-1-sulfate, and sodium sulfopropyl tetradecyl maleate) were prepared in house with purities between 53 and 82%. Physicochemical properties such as the critical micelle concentration, the adsorption isotherm, and the specific adsorption area were determined. The surfmers were then used with constant addition profiles in semicontinuous reactions, and the instantaneous conversions of the main monomers determined. The particle size, amount of coagulum, surface tension, and stability against electrolyte solutions of the latices were evaluated. Films were cast of some of the latices, and the visual appearance and water adsorption were assessed. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 183–1820, 1997     

A Lagrangean Approach to Network Design Problems

Network design is a very important issue in the area of telecommunications and computer networks, where there is a large need for construction of new networks. This is due to technological development (fiber optics for telecommunication) and new ways of usage (Internet for computer networks). Optimal design of such networks requires formulation and solution of new optimization models. In this paper, we formulate several fixed charge network design models, capacitated or uncapacitated, directed or undirected, possibly with staircase costs, and survivability requirements. We propose a common solution approach for all these problems, based on Lagrangean relaxation, subgradient optimization and primal heuristics, which together form a Lagrangean heuristic. The Lagrangean heuristic can be incorporated into a branch-and-bound framework, if the exact optimal solution must be found. The approach has been tested on problems of various structures and sizes, and computational results are presented.     

Quantitative trait loci affecting fertility and calving traits in Swedish dairy cattle

Impaired fertility is the main reason for involuntary culling of dairy cows in Sweden. The objective of this study was to map quantitative trait loci (QTL) influencing fertility and calving traits in the Swedish dairy cattle population. The traits analyzed were number of inseminations, 56-d nonreturn rate, interval from calving to first insemination, fertility treatments, heat intensity score, stillbirth, and calving performance. A genome scan covering 20 bovine chromosomes was performed using 145 microsatellite markers. The mapping population consisted of 10 sires and their 417 sons in a granddaughter design. Nine of the sires were of the Swedish Red Breed, and one was a Swedish Holstein. Least squares regression was used to map loci affecting the analyzed traits, and permutation tests were used to set significance thresholds. Cofactors were used in the analyses of individual chromosomes to adjust for QTL found on other chromosomes. The use of cofactors increased both the number of QTL found and the significance level. In the initial analysis, we found 13 suggestive QTL that were mapped to chromosomes 6, 7, 9, 11, 13, 15, 20, and 29. When cofactors were included, 30 QTL were detected on chromosomes 1, 3, 4, 18, 19, 22, and 25, in addition to the 8 previously mentioned chromosomes. Some of the results from the cofactor analysis may be false positives and require further validation. In conclusion, we were able to map several QTL affecting fertility and calving traits in Swedish dairy cattle.