473 research outputs found
NASA/MSFC ground-based Doppler lidar nocturnal boundary layer experiment (Noblex)
During the summer of 1982, NASA/MSFC's ground-based CO2 Doppler Lidar Velocimeter (DLV) was deployed at the Denver Stapleton Airport as part of NASA's participation in the JAWS (Joint Airport Weather Studies) program. Configured to measure the radial wind component within a 10 km radius, the conically scanning lidar was used to examine the evolution of a nocturnal boundary layer under the conditions of cloud free skies and rolling terrain. A valley drainage flow was detected and a two dimension flow visualization constructed. The depth of the gravity current was -700 meters while the depth of the creek valley was -150 meters. This deep drainage flow was detectable for distances of 30 to 40 km from the exit region of the valley. Although the sample period (2000 to 2300 CST) was short and only one nocturnal boundary layer case examined, the usefulness of the DLV was demonstrated as well as the care that must be exercised in interpreting lidar data taken in a stable boundary layer in the vicinity of subtle terrain features
Influence of coherent mesoscale structures on satellite-based Doppler lidar wind measurements
The influence of coherent mesoscale structures on satellite based Doppler lidar wind measurements was investigated. Range dependent weighting functions and the single shot SNR of scan angle are examined and a space shuttle lidar experiment which used a fixed beam and rotating shuttle is simulated
Evaluation of 2 1-D cloud models for the analysis of VAS soundings
Evaluation of the satellite Visual Infrared Spin Scan Radiometer Atmospheric Sounder (VISSR) has begun to document several of its critical shortcomings as far as numerical cloud models are concerned: excessive smoothing of thermal inversions; imprecise measurement of boundary layer moisture; and tendency to exaggerate atmospheric stability. The sensitivity of 1-D cloud models to their required inputs is stressed with special attention to those parameters obtained from atmospheric soundings taken by the VAS or rawinsonde. In addition to performing model experiments using temperature and moisture profiles having the general characteristics of VAS soundings, standard input sensitivity tests were made and 1-D model performance was compared with observations and the results of a 2-D model experiment using AVE/VAS data (Atmospheric Variability Experiment). Although very encouraging, the results are not sufficient to make any specific conclusions. In general, the VAS soundings are likely to be inadequate to provide the cloud base (and subcloud layer) information needed for inputs to current cumulus models. Above cloud base, the tendency to exaggerate the stability of the atmosphere requires solution before meaningful model experiments are run
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Is good enough 'making do'?: An investigation of inappropriate processing in a small design and build company
Purpose: The aim was to address behaviour that led to inappropriate processing in a small design and build contracting organisation that employs direct labour. The objective was to reduce process waste and improve the value delivered to clients. This formed part of a larger knowledge transfer project (KTP) to improve performance on construction sites through the application of lean thinking.
Methodology: Action research was used to identify and bring about change within the contracting organisation. The method was applied to live construction projects in the social housing sector in the greater London area. The intervention was to raise the awareness of site personnel to the importance of finishing tasks through informal discussions and visual management techniques.
Findings: Raised awareness of the importance of finishing work to allow other trades to follow on unimpeded led to significant improvements in the quality and flow of work. This helped to contribute to significant savings in time and cost.
Practical implications: This applied research is practical and cost effective to apply to live projects managed by small and medium sized contracting organisations.
Academic implications: the observations made reveal a form of waste in construction that has not been widely recognised in the literature on Lean.
Research limitations: Findings relate to a small SME with directly employed labour, therefore the findings have limited applicability. Further applied research is required to determine the generalisation of the approach/findings to organisations that subcontract their labour
Originality/value: Provides a unique insight into the practical application of lean thinking tools and process improvement
Influence of coherent mesoscale structures on satellite-based Doppler lidar wind measurements
Efforts to develop display routines for overlaying gridded and nongridded data sets are discussed. The primary objective is to have the capability to review global patterns of winds and lidar samples; to zoom in on particular wind features or global areas; and to display contours of wind components and derived fields (e.g., divergence, vorticity, deformation, etc.). Current considerations in support of a polar orbiting shuttle lidar mission are discussed. Ground truth for a shuttle lidar experiment may be limited to fortuitous alignment of lidar wind profiles and scheduled rawinsonde profiles. Any improvement on this would require special rawinsonde launches and/or optimization of the shuttle orbit with global wind measurement networks
Optical Holography with Partially Coherent Radiation
Holograms can be formed in light of little or no temporal coherence. The coherence requirements for Gabor in‐line holography are examined. It is shown that, with achromatic interferometers formed from diffraction gratings, the coherence requirements for off‐axis holography are equally low. Finally, two basic approaches to the making of holograms in completely white light are described.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87905/2/242_1.pd
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