Pair Of Ports Research Articles

Discrete Programs for Moving Known Cargos from Origins to Destinations on Time at Minimum Bargeline Fleet Cost

A bargeline which accepts various cargos for timely delivery between pairs of ports in its district must determine the routing and timing of movements of barges and towboats to execute the agreed freight movements at minimum fleet cost. A linear discrete programming model of this optimization problem is developed. The cargo movements to be made and the times needed for transit, loading, and unloading are assumed known. A solution of the model gives the numbers of barges and towboats of each size required to provide the service, with the consequent minimal cost. It also provides a complete schedule for the bargeline, specifying the location and status of the barges, boats, and freight at every time unit of the scheduling period.

Service of Bakor-33 and Corhart-Zac in a glass furnace

Bakor-33 in the main is as good in its physicochemical and service properties as the Corhart-ZAC refractory. The use in the walls of a tank furnace of Bakor-33 and dense silica allowed us to raise the melting temperature from 1480 to 1505–1510°C, to improve the quality of the glass, to prolong the campaign from 22 to 27 months and to melt an extra 46,000 tons of glass or more. When high-temperature melting (above 1500°C) is used it is best to employ Soviet fusion-cast Bakor-33 for the upper course of the tank walls in the melting part if window and technical glass are being produced. It is undesirable to use Bakor-33 blocks in the pouring section inside the furnace. In view of the serious wear of firebrick with high-temperature melting it is recommended that the low-lying courses of the walls of the melting part be made of fused corundum refractory Bakor-20. The first five pairs of ports in the glass furnace should be made of Bakor-33 blocks and the other of silica. To obtain high-grade glass from high-temperature melting it is desirable to make the upper courses of the walls of the cooler and working parts in fused corundum or Bakor-20, and in the extreme case, of high-Al2O3 blocks.

Derivation of n-ports with prescribed insertion-loss characteristics from known two-ports

Simple procedures are presented for finding an n-port, and/or its immittance matrixes, having the same insertion-loss characteristics between every pair of ports, when a realisation is known for n = 2. Various types of symmetry are also defined for n-ports.

Factors in the Attractiveness of Bodies for Mosquitoes

This exhibit represents part of the work of the Department of Zoology in the last 15 years, and others who have contributed to it in the past are L. Burgess, D. G. Peterson, R. P. Thompson, W. L. Sippell and M. R. Smart.The laboratory experiments have been made with Aedes aegypti in a large cage, in which a choice is offered between a pair of objects differing in one factor, or a pair of emission ports for airborne vapours. Thus six factors have been evaluated and their order of importance has been found to be as follows:

UHF Strip Transmission Line Hybrid Junction

A hybrid junction has been developed using a symmetrical strip transmission line for application in the UHF range. It has a frequency band of +- 20 per cent where the input voltage standing-wave ratios at all ports are less than 1.26 (2 db), the power divisions are within 0.1 db, and the difference in power between the series input and parallel input ports is less than 0.3 db. The isolation is greater than 40 db and 24 db, respectively, for the two pairs of conjugate ports. These circuits are relatively small, light-weight, simple to build and reproduce, and are inexpensive. The approximate equivalent circuit of the configuration assuming transmission in the TEM mode is presented. The results of the analysis and the important features in the design and fabrication and a few modifications of the configuration are discussed.

Hybrid Junction--Cutoff Waveguide Filters

Low-pass and band-pass filter characteristics can be obtained in waveguide by the use of an arrangement of a waveguide hybrid junction and lengths of cutoff waveguide. Low-pass filters are obtained by terminating a conjugate pair of ports of the hybrid in identical cutoff waveguide sections through short lengths of phase correcting lines. Band-pass characteristics can be realized by introducing a third cutoff waveguide having a lower cutoff frequency at the input port of the hybrid. These filters have a matched input at all frequencies above the lower end of the pass band and are characterized by low-pass band insertion loss, steep skirt selectivity, and moderate rejection band attenuation. The power handling capabilities of the structure exceed those possible with conventional microwave filter circuits, and the design is particularly well suited for use at frequencies above 10 kmc. Simple techniques are available for constructing filters of this type having variable cutoff frequencies and variable bandwidths.