Cruise noise of the 2/9th scale model of the Large-scale Advanced Propfan (LAP) propeller, SR-7A

Noise data on the Large-scale Advanced Propfan (LAP) propeller model SR-7A were taken in the NASA Lewis Research Center 8 x 6 foot Wind Tunnel. The maximum blade passing tone noise first rises with increasing helical tip Mach number to a peak level, then remains the same or decreases from its peak level when going to higher helical tip Mach numbers. This trend was observed for operation at both constant advance ratio and approximately equal thrust. This noise reduction or, leveling out at high helical tip Mach numbers, points to the use of higher propeller tip speeds as a possible method to limit airplane cabin noise while maintaining high flight speed and efficiency. Projections of the tunnel model data are made to the full scale LAP propeller mounted on the test bed aircraft and compared with predictions. The prediction method is found to be somewhat conservative in that it slightly overpredicts the projected model data at the peak

Supramolecular chemistry and molecular design: self-assembly of molecular squares

Journal ArticleModem supramolecular chemistry has been described as organized polymolecular systems held together by noncovalent interactions and represents one of the major frontiers in the chemical sciences.'-' At present the field is dominated by the hydrogen bonding motif that mimics biological systems and the classical covalent macrocyclics such as crown ethers, cyclophanes, cyclodextrins, calixarenes, etc., that represent the roots of the field!?' Much less is known about the use of coordination and transition metals as a motif for the assembly of supramolecular species

Coupled hygrothermal, electrochemical, and mechanical modelling for deterioration prediction in reinforced cementitious materials

In this paper a coupled hygrothermal, electrochemical, and mechanical modelling approach for the deterioration prediction in cementitious materials is briefly outlined. Deterioration prediction is thereby based on coupled modelling of (i) chemical processes including among others transport of heat and matter as well as phase assemblage on the nano and micro scale, (ii) corrosion of steel including electrochemical processes at the reinforcement surface, and (iii) material performance including corrosion- and load-induced damages on the meso and macro scale. The individual FEM models are fully coupled, i.e. information, such as such as corrosion current density, damage state of concrete cover, etc., are constantly exchanged between the models

A population-based case-control study on social factors and risk of testicular germ cell tumours

Objectives Incidence rates for testicular cancer have risen over the last few decades. Findings of an association between the risk of testicular cancer and social factors are controversial. The association of testicular cancer and different indicators of social factors were examined in this study.<p></p> Design Case–control study.<p></p> Setting Population-based multicentre study in four German regions (city states Bremen and Hamburg, the Saarland region and the city of Essen).<p></p> Participants The study included 797 control participants and 266 participants newly diagnosed with testicular cancer of which 167 cases were classified as seminoma and 99 as non-seminoma. The age of study participants ranged from 15 to 69 years.<p></p> Methods Social position was classified by educational attainment level, posteducational training, occupational sectors according to Erikson-Goldthorpe-Portocarrero (EGP) and the socioeconomic status (SES) on the basis of the International SocioEconomic Index of occupational status (ISEI). ORs and corresponding 95% CIs (95% CIs) were calculated for the whole study sample and for seminoma and non-seminoma separately.<p></p> Results Testicular cancer risk was modestly increased among participants with an apprenticeship (OR=1.7 (95% CI 1.0 to 2.8)) or a university degree (OR=1.6 (95% CI 0.9 to 2.8)) relative to those whose education was limited to school. Analysis of occupational sectors revealed an excess risk for farmers and farm-related occupations. No clear trend was observed for the analyses according to the ISEI-scale.<p></p> Conclusions Social factors based on occupational measures were not a risk factor for testicular cancer in this study. The elevated risk in farmers and farm-related occupations warrants further research including analysis of occupational exposures.<p></p&gt

Development of Technologies for a High Efficiency, Very Low Emission, Diesel Engine for Light Trucks and Sport Utility Vehicles

Cummins Inc., in partnership with the Department of Energy, has developed technology for a new highly efficient, very low emission, diesel engine for light trucks and sport utility vehicles. This work began in April 1997, and started with very aggressive goals for vehicles in the 5751 to 8500 pound GCW weight class. The primary program goals were as follows: (1) EMISSIONS -- NOx = 0.50 g/mi; PM = 0.05 g/mi; CO = 2.8 g/mi; and NMHC = 0.07 g/mi. California decided to issue new and even tougher LEV II light truck regulations late in 1999. EPA also issued its lower Tier 2 regulations late in 2000. The net result was that the targets for this diesel engine project were lowered, and these goals were eventually modified by the publication of Federal Tier 2 emission standards early in 2000 to the following: NOx = 0.07 g/mi; and PM = 0.01 g/mi. (2) FUEL ECONOMY -- The fuel economy goal was 50 percent MPG improvement (combined city/highway) over the 1997 gasoline powered light truck or sport utility vehicle in the vehicle class for which this diesel engine is being designed to replace. The goal for fuel economy remained at 50 percent MPG improvement, even with the emissions goal revisions. (3) COOPERATIVE DEVELOPMENT -- Regular design reviews of the engine program will be conducted with a vehicle manufacturer to insure that the concepts and design specifics are commercially feasible. (DaimlerChrysler has provided Cummins with this design review input.) Cummins has essentially completed a demonstration of proof-of-principle for a diesel engine platform using advanced combustion and fuel system technologies. Cummins reported very early progress in this project, evidence that new diesel engine technology had been developed that demonstrated the feasibility of the above emissions goals. Emissions levels of NOx = 0.4 g/mi and PM = 0.06 g/mi were demonstrated for a 5250 lb. test weight vehicle with passive aftertreatment only. These results were achieved using the full chassis dynamometer FTP-75 test procedure that allowed compliance with the Tier 2 Interim Bin 10 Standards and would apply to vehicles in MY2004 through MY2007 timeframe. In further technology development with active aftertreatment management, Cummins has been able to report that the emissions goals for the Tier 2 Bin 5 standards were met on an engine running the full FTP-75 test procedure. The fuel economy on the chassis tests was measured at over 59 percent MPG improvement over the gasoline engines that are offered in typical SUVs and light trucks. The above demonstration used only in-cylinder fueling for management of the aftertreatment system

Torsion Tests of Tubes

This report presents the results of tests of 63 chromium-molybdenum steel tubes and 102 17st aluminum-alloy tubes of various sizes and lengths made to study the dependence of the torsional strength on both the dimensions of the tube and the physical properties of the tube material. Three types of failure are found to be important for sizes of tubes frequently used in aircraft construction: (1) failure by plastic shear, in which the tube material reached its yield strength before the critical torque was reached; (2) failure by elastic two-lobe buckling, which depended only on the elastic properties of the tube material and the dimensions of the tube; and (3) failure by a combination of (1) and (2) that is, by buckling taking place after some yielding of the tube material

Transdermal fluid loss in severely burned patients

Introduction: The skin protects against fluid and electrolyte loss. Burn injury does affect skin integrity and protection against fluid loss is lost. Thus, a systemic dehydration can be provoked by underestimation of fluid loss through burn wounds

Is It Always Unethical to Use a Placebo in a Clinical Trial?

Background to the debate: Placebos are used in trials to conceal whether a treatment is being given or not and hence to control for the psychosomatic effects of offering treatment. Placebo-controlled trials are controversial. Critics of such trials argue that if a proven effective therapy exists, a placebo should not be used. But proponents argue that placebo trials are still crucial to prove the efficacy and safety of many treatments

Increased mortality in hypernatremic burned patients

Introduction: In-hospital hypernatremia develops usually iatrogenically from inadequate or inappropriate fluid prescription. In severely burned patient an extensive initial fluid resuscitation is necessary for burn shock survival. After recovering of cellular integrity the circulating volume has to be normalized. Hereby extensive water and electrolyte shifts can provoke hypernatremia