Stratospheric scattering of radio waves and the Jicamarca radio telescope

Radar backscatter from the 15 to 35 km height range provides information about the dynamics and turbulent mixing of the stratosphere. The 3-dimensional space spectrum of turbulent fluctuations, the mean wind velocity, and the root-mean-square velocity fluctuations are directly related to the autocorrelation function of the scattered signals. The theory and mechanisms of stratospheric scattering of radio waves is discussed. The equipment and procedures used in previous experiments at the Jicamarca Radio Observatory are examined in detail, and are found to require modification in some cases. The theory of phased arrays is presented, and the correct and complete array factor pertinent to the Jicamarca antenna is derived. Information about the side lobes and precise positions of various beams is considered, and three beams are selected for use in a proposed stratospheric backscatter experiment. The phasing cables needed for the implementation of two off-vertical beams are available at the observatory, while new phasing cables must be manufactured for the realization of the vertical beam

JICAMARCA RADAR MEASUREMENTS OF WINDS AND TURBULENCE IN THE STRATOSPHERE

A series of 48-hour experiments performed quarterly in 1977 to study radar returns from the lower stratosphere is described. Current theories of stratospheric scatter of radio waves are presented and the radar equation pertinent to the large array at Jicamarca, Peru is derived. Observational and data reduction techniques are discussed. Experimental results concerning scattered power, mean wind velocities and velocity fluctuations are presented. It is found that isotropic turbulent scatter is not the only scattering mechanism operating in the stratosphere, and modifications to the radar equation which arise from turbulent rolls or thin layers of refractive index variation are needed. Mean winds measured by radar are comparable to those determined by rawinsonde ascent. Velocity oscillations of approximately 5-minute periods are interpreted as buoyancy oscillations with 2 km horizontal wavelength and phase velocity of 6 m/s. Tidal oscillations with periods of 24 and 12 hours are also observed. Suggestions for future measurements at Jicamarca and other institutions are offered

Improving data quality and supply chain performance with RFID : evidence from the retail industry

The retail industry ranks among the leaders when it comes to supply chain management and the use of inventory and demand data. Industry initiatives such as Efficient Consumer Response advocate close collaboration between manufacturers and retailers. Companies rely heavily on enabling technologies to support business processes: electronic data interchange (EDI) messages are used to transfer point-of-sale (POS) data, orders, and dispatch advices; bar codes allow companies to identify items, cases, and pallets in the supply chain and in the store; and global data synchronization initiatives are aimed at ensuring consistent product master data between trading partners. The grocery supply chain is driven to an ever-greater extent by information, and due to the increasing focus on inventory reduction and frequent, just-in-time deliveries, there is little margin for error. As a consequence, the importance of data quality is growing