Room Airflow Studies Using Sonic Anemometry

Abstract To ensure prompt response by real-time air monitors to an accidental release of toxic aerosols in a workplace, safety professionals should understand airflow patterns. This understanding can be achieved with validated computational fluid dynamics (CFD) computer simulations, or with experimental techniques, such as measurements with smoke, neutrally buoyant markers, trace gases, or trace aerosol particles. As a supplementary technique to quantify airflows, the use of a state-of-the art, three-dimensional sonic anemometer was explored. This instrument allows for the precise measurements of the air-velocity vector components in the range of a few centimeters per second, which is common in many indoor work environments. Measurements of air velocities and directions at selected locations were made for the purpose of providing data for characterizing fundamental aspects of indoor air movement in two ventilated rooms and for comparison to CFD model predictions. One room was a mockup of a plutonium workroom, and the other was an actual functioning plutonium workroom. In the mockup room, air-velocity vector components were measured at 19 locations at three heights (60, 120 and 180 cm) with average velocities varying from 1.4 cm s^?1 to 9.7 cm s^?1. There were complex flow patterns observed with turbulence intensities from 39% up to 108%. In the plutonium workroom, measurements were made at the breathing-zone height, recording average velocities ranging from 9.9 cm s^?1 to 35.5 cm s^?1 with turbulence intensities from 33% to 108%.     

Costing the supply chain

Supply chains, as well as individual organisations have two sources of competitive advantage, value and costs. Improving value to the customer, by offering better products and services. On the other hand, reducing costs can lead to improvements in profitability or market share, by offering lower prices to the customer. All of these benefits, if appropriately shared, can improve the competitive position of both the individual partners and the complete supply chain. The authors offer solutions to some increasingly complex supply network accounting problems.     

Annotated literature survey of microwave ferrite materials and devices

An annotated literature survey covering major development in the area of microwave ferrite materials and devices for the period 1968-1974 is presented.     

Uptake of 137Cs in vegetable crops grown on a contaminated lakebed

Mean concentrations and plant:soil concentration ratios of 137Cs were determined for six vegetable crops grown on an exposed, contaminated lakebed of a former reactor cooling reservoir in South Carolina. Each crop species was grown with or without potassium fertilizer. Selected crops were also irrigated with either reservoir water or groundwater. Subsamples of crops were prepared for human consumption before analysis to determine the extent of any loss. Plant:soil concentration ratios (dry basis) ranged from 0.22 to 6.82, values which were substantially higher than those used in generic assessment models. While there was no statistically significant effect of irrigation source or culinary preparation, the effect of potassium-fertilizer was dramatic. In many cases, concentrations of 137Cs in those plants receiving potassium were less than half of the concentrations in plants that did not receive potassium. Significant differences among species and plant parts for 137Cs concentrations were observed. Dose/risk calculations for the ingestion of these vegetables by a hypothetical 30-y resident indicates the possibility of a lifetime fatal cancer risk well-above the U.S. Environmental Protection Agency's regulatory guideline of 10(-4).     

Active phased array technology using coplanar packaging technology

Until the present time, active phased array antennas have utilized individually packaged transmit/receive (T/R) modules which provide both transmitter and receiver functions on λ/2 wavelength centers. Such modules usually contain five to seven individual GaAs circuits which provide the following functions: transmit amplifier; phase shifter; variable attenuator; T/R switch; and low noise amplifier. This paper describes some recent efforts to eliminate the fabrication of individual modules and to incorporate other functions to multiply fabricated T/R cell paths including: circulator; radiating element; and signal manifolding. Efforts to date have centered on the 2-20 GHz portion of the spectrum and at Ka-band. An experimental test of a 16-element subarray is discussed     

From dust to dose: Effects of forest disturbance on increased inhalation exposure

Ecosystem disturbances that remove vegetation and disturb surface soils are major causes of excessive soil erosion and can result in accelerated transport of soils contaminated with hazardous materials. Accelerated wind erosion in disturbed lands that are contaminated is of particular concern because of potential increased inhalation exposure, yet measurements regarding these relationships are lacking. The importance of this was highlighted when, in May of 2000, the Cerro Grande fire burned over roughly 30% of Los Alamos National Laboratory (LANL), mostly in ponderosa pine (Pinus ponderosa) forest, and through areas with soils containing contaminants, particularly excess depleted and natural uranium. Additionally, post-fire thinning was performed in burned and unburned forests on about 25% of LANL land. The first goal of this study was to assess the potential for increased inhalation dose from uranium contaminated soils via wind-driven resuspension of soil following the Cerro Grande Fire and subsequent forest thinning. This was done through analysis of post-disturbance measurements of uranium air concentrations and their relationships with wind velocity and seasonal vegetation cover. We found a 14% average increase in uranium air concentrations at LANL perimeter locations after the fire, and the greatest air concentrations occurred during the months of April-June when wind velocities are highest, no snow cover, and low vegetation cover. The second goal was to develop a methodology to assess the relative contribution of each disturbance type towards increasing public and worker exposure to these resuspended soils. Measurements of wind-driven dust flux in severely burned, moderately burned, thinned, and unburned/unthinned forest areas were used to assess horizontal dust flux (HDF) in these areas. Using empirically derived relationships between measurements of HDF and respirible dust, coupled with onsite uranium soil concentrations, we estimate relative increases in inhalation doses for workers ranging from 15% to 38%. Despite the potential for increased doses resulting from these forest disturbances, the estimated annual dose rate for the public was <1 microSv yr(-1), which is far below the dose limits for public exposures, and the upper-bound dose rate for a LANL worker was estimated to be 140 microSv yr(-1), far below the 5 x 10(4) microSv yr(-1) occupational dose limit. These results show the importance of ecosystem disturbance in increasing mobility of soil-bound contaminants, which can ultimately increase exposure. However, it is important to investigate the magnitude of the increases when deciding appropriate strategies for management and long-term stewardship of contaminated lands.