Hingeless rotor theory and experiment on vibration reduction by periodic variation of conventional controls

The reduction of the n per rev. pitch-, roll- and vertical vibrations of an n-bladed rotor by n per rev. sinusoidal variations of the collective and cyclic controls is investigated. The numerical results presented refer to a four-bladed, 7.5-foot model and are based on frequency response tests conducted under an Army-sponsored research program. The following subjects are treated: extraction of the rotor transfer functions (.073R hub flapping and model thrust versus servo valve command, amplitude and phase), calculation of servo commands (volts) required to compensate .073R hub flapping (3P and 5P) and model thrust (4P), evaluation of the effect of the vibratory control inputs on blade loads, and theoretical prediction of the root flapbending moments generated by 0 to 5P perturbations of the feathering angle and rotor angle of attack. Five operating conditions are investigated covering advance ratios from approximately 0.2 to 0.85. The feasibility of vibration reduction by periodic variation on conventional controls is evaluated

Rabies Clinic at Mesquakie Settlement

Last summer while finishing some work for a degree at the University of Iowa, I met a sophomore medical student named Ron Terrill. In talking with him I found that he was spending his summer on the Mesquakie Indian Settlement at Tama, Iowa, working to improve the community health on the settlement. His position at the settlement was provided for through the Indian health Service, who had entered into a contract with the University of Iowa to subsidize a medical student for the summer months

Experimental data and theoretical analysis of an operating 100 kW wind turbine

Experimental test data are correlated with analyses of turbine loads and complete system behavior of the ERDA-NASA 100 kW Mod-0 wind turbine generator over a broad range of steady state conditions, as well as during transient conditions. The deficit in the ambient wind field due to the upwind tower turbine support structure is found to be very significant in exciting higher harmonic loads associated with the flapping response of the blade in bending

Calcium(II)3 (3,5-Diisopropylsalicylate)6(H2O)6 Activates Nitric Oxide Synthase: An Accounting for its Action in Decreasing Platelet Aggregation

Purposes of these studies were first; to determine whether or not Calcium(II)3 (3,5- diisopropylsalicylate)6(H2O)6 [Ca(II)3(3,5-DIPS)6], a lipophilic calcium complex, could decrease activated-platelet aggregation, and second; to determine whether or not it is plausible that Ca(II)3(3,5-DIPS)6 decreases activated-platelet aggregation by facilitating the synthesis of Nitric Oxide (NO) by Nitric Oxide Synthase (NOS). The influence of Ca(II)3(3,5-DIPS)6 on the initial rate of activated-platelet aggregation was determined by measuring the decrease in rate of increase in transmission at 550 nm for a suspension of Thrombin-CaCl2 activated platelets following the addition of 0, 50, 100, 250, or 500 μM Ca(II)3(3,5-DIPS)6. To establish that the Ca(lI)3(3,5- DIPS)6-mediated decrease in aggregation was due to activation of NOS, the effect of ʟ-NMMA, an inhibitor of NOS, on the inhibition of platelet aggregation by Ca(II)3(3,5-DIPS)6 was determined using a suspension of activated platelets contaimng 0 or 250 μM Ca(II)3(3,5-DIPS)6 without or with 1 mM ʟ-NMMA. An in vitro Bovine Brain NOS reaction mixture, containing CaCl2 for the activation of Phosphodiesterase-3' ,5'-Cyclic Nucleotide Activator required for the activation of NOS, was used to determine whether or not Ca(II)3(3,5-DIPS)6 could be used as a substitute for the addition of Ca. The decrease in absorbance at 340 nm, lambda maximum for NADPH, was measured to determine NOS activity following the addition of NOS to the complete reaction mixture containing either CaCl2, Ca(II)3(3,5-DIPS)6, or neither Ca compound. Increasing the concentration of Ca(II)3(3,5-DIPS)6 caused a concentration related decrease in activated platelet aggregation. The addition of ʟ-NMMA to activated platelets, in the absence of Ca(II)3(3,5-DIPS)6, caused a 129% increase in initial rate of platelet aggregation. The initial rate of platelet aggregation decreased 74% with the addition of 250 μM Ca(II)3(3,5-DIPS)6 and the addition of ʟ-NMMA plus 250 μM Ca(II)3(3,5-DIPS)6 caused a 197% decrease in initial rate of aggregation compared to the initial rate observed width the presence of 1 mM ʟ-NMMA alone. There was only a small, 27%, increase in initial rate of 0.4 mM NADPH oxidation when 0.9 mM CaCl2 was added to the NOS reaction mixture in comparison to the initial rate of NADPH oxidation with no addition of CaCI2. Addition of an equivalent amount of Ca in the form of Ca(II)3(3,5-DIPS)6, 333 μM, caused a 37% increase in initial rate of NADPH oxidation compared to the addition of 0.9 mM CaCl2. Addition of increasing concentrations of ʟ-NMMA plus 0.9 mM CaCl2 or 333 μM Ca(II)3(3,5-DIPS)6 to the NOS reaction mixture caused a concentration related increase in initial rate of NADPH oxidation. Addition of ʟ-NMMA while expected to decrease NADPH oxidation actually increased the rate of NADPH oxidation. Additions of 133 μM or 267 μM Ca(II)3(3,5- DIPS)6 also caused concentration related increases in initial rate of NADPH oxidation in the presence of 113 μM ʟ-NMMA. However, the addition of 533 μM Ca(II)3(3,5-DIPS)6 caused a dramatic decrease in initial rate of NADPH oxidation by NOS. It is concluded that: 1) Ca(II)3(3,5- DIPS)6 activates platelet NOS in preventing platelet aggregation, 2) in vitro NOS activity can be observed spectrophotometrically by following the consumption of NADPH as a decrease in absorbance at 340 nm, 3) Ca(II)3(3,5-DIPS)6 plays a role in enhancing Bovine Brain NOS activity resulting in an increased rate of NADPH oxidation by NOS, 4) Ca(II)3(3,5-DIPS)6 is a useful form of Ca in activating NOS and superior to CaCl2 with regard to the facilitation of a NADPH oxidation, and 5) ʟ-NMMA stimulates Bovine Brain NOS activity rather than causing an inhibition of this enzyme and must serve as a reducible substrate for Bovine Brain NOS

Task-Based Noise Exposures for Farmers Involved in Grain Production

Few studies have been done examining noise exposures associated with agricultural tasks. This study was conducted to address that research gap by calculating the noise exposures for tasks and equipment associated with grain production and assessing the variability in those exposures. An additional aim of this study was to identify tasks and equipment that could be targeted for intervention strategies as a means toward reducing the total noise exposures of farmers and farm workers. Through the use of personal noise dosimetry and direct observation, over 30,000 one-minute noise exposure measurements and corresponding task and equipment data were collected on 18 farms and compiled into a task-based noise exposure database. Mean noise exposures were calculated for 23 tasks and 18 pieces of equipment. The noise exposures for the tasks and equipment ranged from 78.6 to 99.9 dBA and from 80.8 to 96.2 dBA, respectively, with most of the noise exposures having a large standard deviation and maximum noise exposure level. Most of the variability in the task and equipment noise exposures was attributable to within-farm variations (e.g., work practices, distance from noise sources). Comparisons of the mean noise exposures for the agricultural tasks and equipment revealed that most were not statistically different. Grain production tasks and equipment with high mean noise exposures were identified. However the substantial variability in the noise exposures and the occurrence of intense noise measurements for nearly every task and piece of equipment indicate that targeting a few specific tasks or equipment for intervention strategies would reduce lifetime noise exposure but would not completely eliminate exposure to hazardous noise levels

Geocoding accuracy and the recovery of relationships between environmental exposures and health

<p>Abstract</p> <p>Background</p> <p>This research develops methods for determining the effect of geocoding quality on relationships between environmental exposures and health. The likelihood of detecting an existing relationship – statistical power – between measures of environmental exposures and health depends not only on the strength of the relationship but also on the level of positional accuracy and completeness of the geocodes from which the measures of environmental exposure are made. This paper summarizes the results of simulation studies conducted to examine the impact of inaccuracies of geocoded addresses generated by three types of geocoding processes: a) addresses located on orthophoto maps, b) addresses matched to TIGER files (U.S Census or their derivative street files); and, c) addresses from E-911 geocodes (developed by local authorities for emergency dispatch purposes).</p> <p>Results</p> <p>The simulated odds of disease using exposures modelled from the highest quality geocodes could be sufficiently recovered using other, more commonly used, geocoding processes such as TIGER and E-911; however, the strength of the odds relationship between disease exposures modelled at geocodes generally declined with decreasing geocoding accuracy.</p> <p>Conclusion</p> <p>Although these specific results cannot be generalized to new situations, the methods used to determine the sensitivity of results can be used in new situations. Estimated measures of positional accuracy must be used in the interpretation of results of analyses that investigate relationships between health outcomes and exposures measured at residential locations. Analyses similar to those employed in this paper can be used to validate interpretation of results from empirical analyses that use geocoded locations with estimated measures of positional accuracy.</p

Retrofitting Tractors with Rollover Protective Structures: Perspective of Equipment Dealers

This study was one of a cluster of studies that originated via requests for proposals from the NIOSH National Agricultural Tractor Safety Initiative. The present study design consisted of several steps: (1) formation of an advisory group, (2) development and testing of a standard paper self-responding survey instrument, (3) sample selection of farm equipment dealers, (4) administration of the survey, (5) assessment and analysis of the survey, and (6) in-person response panel of dealers (n = 80) to review results of the questionnaire for further definition and sharpening of the recommendations from the survey. A key finding is that most dealers do not currently sell or install ROPS retrofit kits. Barriers cited by dealers included (1) actual or perceived lack of farmer demand, (2) injury liability, (3) expensive freight for ordering ROPS, (4) lack of dealer awareness of the magnitude of deaths from tractor overturns and the high life-protective factor of ROPS, and (5) difficulty and incursion of non-recoverable expenses in locating and obtaining specific ROPS. Despite not currently selling or installing ROPS, dealers responded favorably about their future potential role in ROPS promotion and sales. Dealers were willing to further promote, sell, and install ROPS if there was demand from farmers. Recommendations include establishing a ROPS “clearing house” that dealers could contact to facilitate locating and obtaining ROPS orders from customers. Additional recommendations include education and social marketing targeting farm machinery dealers as well farmers, manufacturers, and policy makers