We analyze the throughput, delay and energy efficiency performance of space diversity slotted ALOHA when multibeam smart antenna arrays, capable of steering the beams selectively on smaller sectors, are used at the base station receiver. Analytical expressions to establish the effect of diITerent beamwidths, number of beams, beam steering patterns, and beam service times on the achieved perform...

Geometry of eccentrically braced frames (EBFs) in some cases causes the connection of link beam to the column. The details of such conditions should be studied carefully due to the full plastic rotation in the link beam. In this research, the behavior of link-to-column connection is modeled and the failure modes are considered. Based on the previous researches shear link can exhibit better beha...

1. Introduction This paper proposes beam scan by moving dielectric blocks mechanically in the feed waveguide of single-layer slotted waveguide arrays as shown in Fig.1. Millimeter-wave antennas with beam scan are desired in various systems such as collision-avoidance car radars [1-3]. Electrical scanning is the best but mechanical one is still attractive in terms of cost, efficiency, heat-radia...

For the CLIC two-beam scheme, a high-current, longpulse drive beam is required for RF power generation. Taking advantage of the 3 GHz klystrons available at the LEP injector once LEP stops, a 180 MeV electron accelerator is being constructed for a nominal beam current of 3.5 A and 1.5 Ps pulse length. The high current requires highly effective suppression of dipolar wakes. Two concepts are inve...

A wavelength division multiplexed link is to be time shared by a given collection of optical connections. The system is time slotted with period T. Each optical connection has a prescribed duration per time period. In addition, it has a prescribed time window within which its duration may begin. The size of the window is the amount of time flexibility there is to schedule the optical connection...

Introduction This Light Source Note summarizes the results of the single crystal monochromator high-heat-load tests performed at the CHESS F-2 wiggler station. The results from two different cooling geometries will be presented: (1) the "pin-post" crystal and (2) the "criss-cross" crystal. The data presented were taken in August 1993 (water-cooled pin-post) and in April 1995 (water-and gallium-...

A new calibration method for slotted disk velocity selectors is presented and is compared with other calibration procedures. It is based on the measurement of the velocity distribution of a supersonic molecular beam produced by a room temperature source. The error due to the assumed theoretical distribution and to experimental procedure is discussed. It is shown that the velocity scale is known...