The wave numbers of supercritical surface tension driven Benard convection

The cell size or the wave numbers of supercritical hexagonal convection cells in primarily surface tension driven convection on a uniformly heated plate was studied experimentally in thermal equilibrium in thin layers of silicone oil of large aspect ratio. It was found that the cell size decreases with increased temperature difference in the slightly supercritical range, and that the cell size is unique within the experimental error. It was also observed that the cell size reaches a minimum and begins to increase at larger temperature differences. This reversal of the rate of change of the wave number with temperature difference is attributed to influences of buoyancy on the fluid motion. The consequences of buoyancy were tested with three fluid layers of different depth

Attracting Newcomers to Canada’s Prairie West, 1896-1905: The Selling of the West and the Persuasiveness within the Government’s Promotional Booklets

Abstract: The prairie west of Canada was, nearing the turn of the twentieth century, considered to be empty, having not yet reached its assimilatory, and resource, economic, social or cultural potential. Many politicians, especially Clifford Sifton, sought to change this. Sifton eventually made Canada’s population increase a reality. He masterminded the most successful promotional campaign within Canada’s immigration policy to ever stretch the parameters of inclusion for enlarging the Canadian mosaic. The largest phenomenon of human migration to the Canadian prairie west was between 1896 and 1905. Sifton’s intercontinental and overseas promotional campaign became the magnet of attraction for newcomers eager to settle the prairie west. Although a great deal of work has been done by Canadian and American scholars on the topic of prairie west settlement and immigration history, none have incorporated an analysis of Clifford Sifton’s promotional campaign’s promotional literature, namely, the promotional booklets. This essay takes into consideration the history of prairie west settlement until 1896, shows the circumstances for favourable settlement in the prairie west during Sifton’s time as Minister of the Interior, and, more importantly, analytically unpacks two Federal Government booklets’ propaganda-like designs. It is within these booklets where pompous claims, pastoral narratives, first-person perspectives and romanticized conceptions showcase the acumen of the booklets’ authors. As for the structure of the booklets, they were meant to be an ‘easy sell’ not only tactically but surreptitiously as well. This acted as a turning point for prospective and desirable settlers to choose to live in the west. The booklet’s explicit use of propaganda techniques and rhetoric convinced people to buy into the incontestably lucrative agricultural opportunities and supposed charming lifestyle the prairie west offered

Scaling-up experiments of smouldering combustion as a remediation technology for contaminated soil

Self-sustaining Treatment for Active Remediation (STAR) is a novel, patent-pending process that uses smouldering combustion as a remediation technology for land contaminated with hazardous organic liquids. Compounds such as chlorinated solvents, coal tar and petroleum products, called Non-Aqueous Phase Liquids (NAPLs) for their low miscibility with water, have a long history of use in the industrialised world and are among the most ubiquitous of contaminants worldwide. These contaminants are toxic and many are suspected or known carcinogens. Existing remediation technologies are expensive and ineffective at reducing NAPL source zones sufficiently to restore affected water resources to appropriate quality levels. STAR introduces a self-sustaining smouldering reaction within the NAPL pool in the subsurface and allows that reaction to provide all of the post-ignition energy required by the reaction to completely remediate the NAPL source zone in the soil. Results from laboratory and field experiments have been very promising. Laboratory experiments have demonstrated STAR across a wide range of NAPL fuels and focused on coal tar to identify key parameters for successful remediation. Modelling has suggested that STAR efficiency will improve with scale as effects such as heat losses from boundaries become less significant. Observations from field experiments support the modelling theory - significantly lower relative air flow in a smouldering field experiment (330L) led to faster smouldering front propagation than observed in laboratory experiments (1L and 3L). Preliminary emissions monitoring by Fourier Transform Infrared (FTIR) spectroscopy has suggested that STAR emissions might be low enough to meet regulatory requirements, but further study is necessary. As emissions are expected to vary with each contaminant, activated carbon filters are being developed and tested in case emissions filtration is necessary. Experiments at all scales have demonstrated that STAR is controllable and self-terminating. Pilot-scale (2500L) field trials are underway to demonstrate STAR on excavated contaminated soil. The materials that will be studied in these trials are manufactured coal tar in coarse sand (which is the same material as used in the laboratory and field experiments) as well as two soils obtained from coal tar contaminated sites. This poster focuses on the scale-up to these field trials, including small scale characterisation, large scale performance, emissions monitoring and post-treatment soil analysis

Experimental studies of self-sustaining thermal aquifer remediation (STAR) for non-aqueous phase liquid (NAPL) sources

Self-sustaining Thermal Aquifer Remediation (STAR) is a novel technology that employs smouldering combustion for the remediation of subsurface contamination by non-aqueous phase liquids (NAPLs). Smouldering is a form of combustion that is slower and less energetic than flaming combustion. Familiar examples of smouldering involve solid fuels that are destroyed by the reaction (e.g., a smouldering cigarette or peat smouldering after a wildfire). In STAR, the NAPL serves as the fuel within an inert, porous soil medium. Results from experiments across a range of scales are very promising. Detailed characterisation has focused on coal tar, a common denser-than-water NAPL (DNAPL) contaminant. Complete remediation is demonstrated across this range of scales. Visual observations are supported bychemical extraction results. Further experiments suggest that STAR can be self-sustaining, meaning that once ignited the process can supply its own energy to propagate. Costly energy input is reduced significantly. Comparison of large scale to small scale laboratory experiments, a volume increase by a factor of 100, suggests that STAR process efficiency increases with scale. This increase in efficiency results from reduced heat losses at larger scales while maximum the temperature achieved by STAR is unaffected. The research also demonstrates the controllability of STAR, where the termination of airflow to the reaction terminates the STAR process. The scale-up process provides important guidance to the development of full scale STAR for ex situ remediation of NAPL-contaminated soil

Primordial helium recombination III: Thomson scattering, isotope shifts, and cumulative results

Upcoming precision measurements of the temperature anisotropy of the cosmic microwave background (CMB) at high multipoles will need to be complemented by a more complete understanding of recombination, which determines the damping of anisotropies on these scales. This is the third in a series of papers describing an accurate theory of HeI and HeII recombination. Here we describe the effect of Thomson scattering, the $^3$He isotope shift, the contribution of rare decays, collisional processes, and peculiar motion. These effects are found to be negligible: Thomson and $^3$He scattering modify the free electron fraction $x_e$ at the level of several $\times 10^{-4}$. The uncertainty in the $2^3P^o-1^1S$ rate is significant, and for conservative estimates gives uncertainties in $x_e$ of order $10^{-3}$. We describe several convergence tests for the atomic level code and its inputs, derive an overall $C_\ell$ error budget, and relate shifts in $x_e(z)$ to the changes in $C_\ell$, which are at the level of 0.5% at $\ell =3000$. Finally, we summarize the main corrections developed thus far. The remaining uncertainty from known effects is $\sim 0.3$ in $x_e$.Comment: 19 pages, 15 figures, to be submitted to PR

Business in Nebraska #292 - January 1969

Changing Patterns of Communities in the Midwest (Dorothy Switzer) The regional concept of economic planning and development discussed in the December issue of Business in Nebraska was the subject also of a workshop conference on Changing Patterns of People and Communities in the Midwest, held in Omaha last month. It is deemed appropriate to report here the most significant highlight of the conference because the panel presentations and subsequent discussions further developed several important apects of regional growth. Business Summary (R. L. Busboom) Both Physical Volume and Dollar Volume Indexes for Nebraska indicate that the October, 1968 level of business activity was above that of October, 1967. For the U.S. these indexes increased over the same period at a rate slightly more than Nebraska\u27s. From September, 1968, to October, 1968, Nebraska\u27s dollar and physical volumes fell, being down about 1.6 percent. The indexes for the U.S. show some increase, with physical volume up 2.1% and dollar volume up 3.4%. Review

Business in Nebraska # 270 - March 1967

Nebraska\u27s Agricultural Exports (Dorothy Switzer) Importance of Nebraska as the 9th ranking state in the nation and 4th in the top-ranking region, the West North Central, in value of agricultural commodity shipments in fiscal 1965-66 has been revealed in a new study by the Economic Research Service of the I.S. Department of Agriculture. Because Nebraska is one of the ten leading states in farm exports in this country, which is in turn the world\u27s largest exporter of such commodities, explicit world market information pertaining to the state has long been sought. The significance of such information is considerable both to Nebraska farmers and to that part of the business community dependent, to whatever extent, upon the agricultural sector of the economy. Business Summary (E. L. Burgess) December\u27s dollar volume of business in Nebraska increased 2.2% over last year compared with a 4.0% increase for the U.S. Nebraska\u27s physical volume changes from last month +4.9% and +1.1% respectively. construction activity in Nebraska remained down from the previous year (-16.1%). The only other indicator showing a decline from a year ago for Nebraska was electricity produced (-1.6%)

Factors affecting the spatial distribution of oviposition sites for tandem black saddlebags dragonflies (Odonata: Libellulidae)

Oviposition site location may be affected by (1) factors influencing the costs and benefits to the offspring (e.g., resource availability, competition, predation risk) and (2) factors influencing the costs and benefits to the female (e.g., predation risk or mate ha- rassment). In cases in which both the male and female are involved in locating a site, costs and benefits may differ for each parent and the resulting oviposition site location may represent the outcome of selection pressures on one or both of them. We studied oviposi- tion behavior in the black saddlebags dragonfly (Tramea lacerata Hagen), a species in which the male and female typically remain to- gether (i.e., in tandem) while traveling among potential oviposition locations. Oviposition sites tended to be away from pond shoreline at the outer edge of the vegetation on the water’s surface. We found that tandems distributed their oviposition locations widely around the pond, and interactions with other dragonflies (typically other T. lacerata, either territorial males or tandems) led to a larger distance between consecutive oviposition locations. Interestingly, for 10% of the tandems, the female became separated from the male and oviposited solitarily multiple times. These solitary females spent significantly less time and traveled significantly smaller distances between successive oviposition sites than when in tandem. Our results indicate that while some aspects of oviposition behavior and site selection may be consistent between the male and female (e.g., the characteristics that make a site suitable), other aspects, such as the distribution of sites, may be a result of a differing benefits and costs for the two sexes, perhaps as a consequence of potential sperm competition

Small-scale forward smouldering experiments for remediation of coal tar in inert media

This paper presents a series of experiments conducted to assess the potential of smouldering combustion as a novel technology for remediation of contaminated land by water-immiscible organic compounds. The results from a detailed study of the conditions under which a smouldering reaction propagates in sand embedded with coal tar are presented. The objective of the study is to provide further understanding of the governing mechanisms of smouldering combustion of liquids in porous media. A small-scale apparatus consisting of a 100 mm in diameter quartz cylinder arranged in an upward configuration was used for the experiments. Thermocouple measurements and visible digital imaging served to track and characterize the ignition and propagation of the smouldering reaction. These two diagnostics are combined here to provide valuable information on the development of the reaction front. Post-treatment analyses of the sand were used to assess the amount of coal tar remaining in the soil. Experiments explored a range of inlet airflows and fuel concentrations. The smouldering ignition of coal tar was achieved for all the conditions presented here and self-sustained propagation was established after the igniter was turned off. It was found that the combustion is oxygen limited and peak temperatures in the range 800-1080 °C were observed. The peak temperature increased with the airflow at the lower range of flows but decreased with airflow at the higher range of flows. Higher airflows were found to produce faster propagation. Higher fuel concentrations were found to produce higher peak temperatures and slower propagation. The measured mass removal of coal tar was above 99% for sand obtained from the core and 98% for sand in the periphery of the apparatus