86,910 research outputs found

    Staphylinidae from Under Bark and at Sap of Trees, a Preliminary Survey of Species Possibly Beneficial to Forestry (Coleoptera)

    Get PDF
    Two hundred and one species of Staphylinidae known to be found under bark or at sap of trees are listed. The possibility of these insects being important elements in the population dynamics of forest pests is discussed. An indication is given of the distribution and habitat of each species

    Development of nondestructive testing techniques for honeycomb heat shields, volume I Final report, 1 Jul. 1964 - 29 Sep. 1966

    Get PDF
    Development of nondestructive testing system, using ultrasonic techniques, for detecting disbonds in composite honeycomb heat shields of Saturn launch vehicl

    A study of the temporal changes recorded by ERTS and their geological significance

    Get PDF
    The temporal changes that are recorded by ERTS were evaluated for an area around Bathurst Inlet in the North West Territories. The seasons represented by the images included: early winter, spring, early summer, summer, and fall. Numerous surface characteristics (vegetation, drainage patterns, surface texture, lineament systems and topographic relief, etc.) were used to relate the change in observable features with the different seasons. It was found that the time of year when an observation is made has a strong control over the amount and type of information that can be derived by an experienced interpreter. It was concluded that a detailed study of temporal changes is an important part of any ERTS interpretation for geology

    Retirement Wealth Accumulation and Decumulation: New Developments and Outstanding Opportunities

    Get PDF
    Analysts have raised serious questions about current workers' ability and inclination to save enough for retirement. This is of obvious policy interest given the need to reform national retirement income programs. In the present paper we examine recent research developments regarding retirement wealth accumulation and decumulation. Our goal is to identify new developments and outstanding opportunities to encourage a more sensible process of growing and then drawing down retirement wealth.

    An experimental study of a self-confined flow with ring-vorticity distribution

    Get PDF
    A new form of self-confined flow was investigated in which a recirculation zone forms away from any solid boundary. An inviscid flow analysis indicated that in a purely meridional axisymmetric flow a stationary, spherical, self-confined region should occur in the center of a streamlined divergent-convergent enlargement zone. The spherical confinement region would be at rest and at constant pressure. Experimental investigations were carried out in a specially built test apparatus to establish the desired confined flow. The streamlined divergent-convergent interior shape of the test section was fabricated according to the theoretical calculation for a particular streamline. The required inlet vorticity distribution was generated by producing a velocity profile with a shaped gauze screen in the straight pipe upstream of the test section. Fluid speed and turbulence intensity were measured with a constant-temperature hot-wire anemometer system. The measured results indicated a very orderly and stable flow field

    A theory of post-stall transients in multistage axial compression systems

    Get PDF
    A theory is presented for post stall transients in multistage axial compressors. The theory leads to a set of coupled first-order ordinary differential equations capable of describing the growth and possible decay of a rotating-stall cell during a compressor mass-flow transient. These changing flow features are shown to have a significant effect on the instantaneous compressor pumping characteristic during unsteady operation, and henace on the overall system behavior. It is also found from the theory that the ultimate mode of system response, stable rotating stall or surge, depends not only on the B parameter but also on other parameters, such as the compressor length-to-diameter ratio. Small values of this latter quantity tend to favor the occurrence of surge, as do large values of B. A limited parametric study is carried out to show the impact of the different system features on transient behavior. Based on analytical and numerical results, several specific topics are suggested for future research on post-stall transients

    Retirement Wealth Accumulation and Decumulation: New Developments and Outstanding Opportunities

    Get PDF
    Analysts have raised questions about current workers' ability and inclination to save" enough for retirement. This issue is of obvious policy interest given the current debate over" reforming national retirement income programs. This paper explores the implications of recent" research regarding retirement wealth accumulation and decumulation for this debate. Our goal is" to identify problems and opportunities in the area of preparedness for retirement."

    Radar spectral measurements of vegetation

    Get PDF
    Spectral data of 4-8 GHz radar backscatter were gathered during the 1972 growing season at look angles between 0 and 70 deg and for all four possible polarization linear combinations. The data covers four crop types (corn, milo, alfalfa, and soybeans) and a wide range of soil moisture content. To insure statistical representation of the results, measurements were conducted over 128 fields corresponding to a total of about 40,000 data points. The use of spectral response signatures to separate different crop types and to separate healthy corn from blighted corn was investigated

    Evaluation criteria for commercially oriented materials processing in space proposals

    Get PDF
    An approach and criteria for evaluating NASA funded experiments and demonstrations which have commercial potential were developed. Methods for insuring quick initial screening of commercial proposals are presented. Recommendations are given for modifying the current evaluation approach. New criteria for evaluating commercially orientated materials processing in space (MPS) proposals are introduced. The process for selection of qualified individuals to evaluate the phases of this approach and criteria is considered and guidelines are set for its implementation
    corecore