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Dual Mode Transit has been suggested as a possible solution to some of the problems associated with transportation in the world today. This paper summarizes the program developed by the Urban Mass Transportation Administration in order to develop and test the Dual Mode concept from the viewpoint of GM, one of the contractors participating in the Concept Design phase of the program. The baseline system design proposed by the contractor and the general scenario which Dual Mode Transit is intended to satisfy are also covered in some detail.

The design principles for dual-mode reciprocal latching ferrite phase shifters are relatively well understood at present. Discussions of a few selected topics not previously studied are presented in this paper. A tradeoff analysis is carried out for X-band units to show the interrelation between phase-shifter weight and insertion loss. An interesting consequence of this analysis is the theoretical prediction of an optimum range of values for the saturation moment of the ferrite material. Switching energy in the presence of shorted-turn damping is also analyzed and related to the geometry and hysteresis loss of the ferrite material. Finally, a discussion of manufacturing considerations and unit cost at high rates of production is carried out. The major conclusion is that unit cost levels approaching $10.00 are possible for a production run sufficiently large to justify the substantial cost of engineering and tooling for high rates of manufacture.

We examine a data-rate synchronization system capable of operating in two modes: (i) in master-to-slave mode when the data stations are connected by digital transmission facilities, and (ii) in slave-to-slave mode when the data stations are connected by analog transmission facilities. The first part of this paper determines the steady-state behavior and the transient response in the master-to-slave mode. The results show that the system is well behaved in the transient stage, and that the steady-state behavior is satisfactory. From the transient analysis, the buffer size requirements of the system and the counter size requirements of the rate-locked loops are determined. Formulas are developed from which the start-up time of the system can be estimated. The second part of this paper examines the behavior of the system in the slave-to-slave mode. It is shown that the data stations can settle to the same steady-state signaling rate, and this signaling rate is determined. The dependence of this signaling rate on other system parameters is examined. It is shown that the system can be easily designed such that the steady-state signaling rate will lie within desired limits. (This is so regardless of the starting sequence, the initial system conditions, and time delays in the communication channels.)

The cross polarized radiation for linearly polarized excitation and the beam displacement for circularly polarized excitation have been investigated for offset reflector antennas. Numerical calculations are given to illustrate the dependence upon the angle \theta_{0} between the feed axis and the reflector axis as well as upon the half-angle \theta_{c} subtended at the focus by the reflector. In the case \theta_{0} = \theta_{c} = 45\deg , measured results have been obtained for both linearly and circularly polarized excitations with a dual mode feed illuminating an offset paraboloid. The cross polarized radiation of horn reflector and open Cassegrainian antennas rises sharply to rather high values off the beam axis; however, in general, the maximum cross polarized radiation of offset reflector antennas can be made small by using a small angle between the feed and reflector axes. The cross polarization caused by offset is compared with that caused by an unbalanced feed pattern. The effect of the longitudinal current distribution and of departure of the surface from a paraboloid on cross polarization are also examined. The clarification of these cross polarization properties is found to be valuable in the design of reflector antennas.

Free vibrations in normal modes are examined for a system consisting of two unequal (or equal) masses, interconnected by a nonlinear coupling spring, and each mass connected by nonlinear unequal (or equal) anchor springs to fixed points. All spring forces are odd functions, and proportional to the k’th power, of the spring deflections, where k is a real, positive number. The frequency-amplitude relations for the in and out-of-phase modes are derived without approximation, the stability of these modes is analyzed, and several numerical examples are worked out. A surprising feature of these systems is that they may have a greater number of normal modes than they have degrees of freedom.

An adaptive dual-mode coding system for television signals is described. Its main features are a low bit rate (1.5 bits per sample), the high quality of the reproduced picture, and its moderate hardware. The system is based on the statistical properties of video signals. Specifically, it makes use of the nonuniform spectrum of video signals in the form of a differential scheme containing linear prediction. Furthermore, areas of small amplitude changes between consecutive samples whose probability of occurrence is high are encoded with a reduced coding alphabet. Transients representing sharp edges in the picture are encoded and reproduced with little slope overload and busyness. A method for the buffering of the asynchronous data stream produced by the coder to match a synchronous channel is given.

A system consisting of two unequal masses, interconnected by a coupling spring, and each connected to an anchor spring, is examined. The springs may all be unequal and nonlinear, but each resists being compressed to the same degree as being stretched. The concept of normal modes is rigorously defined, and methods of finding them are given. A knowledge of these modes reduces the coupled system to two uncoupled ones which can always be integrated in quadrature. There exists an infinity of systems, of which the linear is one, which can be integrated in closed form. This approach yields, even for the linear system, new results of great simplicity.

Coupling of a modern dual mode image intensifier with a l05mm spot-film camera has resulted in resolution approaching that available in studies obtained with large film-changers. In comparison to the large film-changer techniques, use of this system in the investigation of coronary artery disease has yielded studies of excellent quality with greater safety and less expense to the patient. Recommendations are made concerning radiological techniques and processing. The 105mm photofluorographic technique may be applied in other forms of selective arteriography when the area of interest is relatively small.

This paper discusses the theoretical analysis and experimental verification of a dual-mode quasi-linear servo-mechanism. After a brief review of the operation of the simple dual-mode servo system, the desirability of linear operation for small errors is pointed out. A method of producing a gradual transition from one mode of operation to the other and finally to nearly linear operation is investigated.

IMPORTANT SYSTEM PROBLEMS ASSOCIATED WITH THE OPERATION OF AN AUTOMATED HIGHWAY NETWORK ARE EXAMINED UNDER THE ASSUMPTION THAT THE SYNCHRONOUS MOVING CELL CONTROL SCHEME IS THE BASIS FOR INDIVIDUAL VEHICLE CONTROL. THE FUNDAMENTALS OF A NETWORK TRAFFIC MANAGEMENT STRATEGY ARE DISCUSSED AND IMPORTANT CONSTRAINTS THAT ARE IMPOSED ON CONTROL SYSTEM DESIGN BY SUCH A STRATEGY ARE STATED. THE PAPER INDICATES THE DEPENDENCE OF EFFECTIVE NETWORK CAPACITY ON THE RULES OF THE TRAFFIC MANAGEMENT STRATEGY, ON THE DESIGN OF INTERCHANGES FOR AUTOMATED HIGHWAYS, AND ON VEHICLE PERFORMANCE AND PASSENGER COMFORT CONSIDERATIONS. A LISTING OF IMPORTANT RESEARCH QUESTIONS ASSOCIATED WITH AUTOMATED HIGHWAY NETWORK OPERATING STRATEGY AND CONTROL SYSTEM DESIGN IS ALSO GIVEN. /TR/

The control problems associated with the operation of a network of automatically controlled closely spaced high-speed vehicles are considered. A system operating concept based on the synchronous moving-cell approach to individual vehicle control is presented. The need for a network traffic-management strategy is pointed out and one such strategy, called cycle preprogramming, is discussed. Finally, a study of the efficiency of the cycle preprogramming traffic-management strategy is described.

This correspondence deals with the analysis and measurement of TE/sub 11/ /spl deg/ /spl rarr/ TM/sub 11/ /spl deg/ mode conversion by circularly symmetric transducers in a circular waveguide. Two types are considered, the simple step change in radius and a discontinuity covered by a dielectric ring. For the first type, experimental results for both amplitude and phase are compared with predictions made on the basis of a computer program, with excellent agreement. The dielectric loaded transducer is of great interest since measurements have shown that such a device can be designed to launch the two modes with a relative amplitude and phase which is essentially independent of frequency over a very wide range. This configuration is therefore an excellent candidate for use in low-noise microwave antenna systems.

A technique has been developed for making precise measurements of refractive index dispersion in gases. The instrument, termed ``dispersometer,'' uses a cavity resonating in two modes simultaneously to measure the difference in index at two frequencies. Since the gas sample is common to both modes, effects of variations in gas pressure, temperature, and composition between samples are removed. In an early model, the precision of the measured dispersion was a few parts in 108 (of refractive index). The method has been used to date for a study of the 0.74 cm−1 water vapor line (reported separately) and should be equally applicable to other spectral regions, limited only by the available generation and detection devices.

The development of a dual-mode traveling wave tube amplifier will be described. The device combines some of the most advanced design features devised to-date, to achieve what amounts to a breakthrough in rf performance. Relevant portions of the design approach will be discussed, as well as some of the obstacles encountered during: development. The tube incorporates shadow grid electron gun control, a S m C o PPM-focusing stack and a conduction-cooled, single-stage depressed collector.

Sorption kinetics and equilibria for C02, A, and CO in polycarbonate were studied over a range of temperatures from 25°C to 120°C (Tg ≈ 150°C) and pressures from 3 to 23 atm. abs. The dual mode sorption model of Vieth and Sladek (1) was used to test the data. The microvoid free volume fraction was found to be the same as that for glassy polystyrene (2).

In applying gas turbines to vehicular applications, gas turbine designers have been faced with design restraints imposed by the limitations of conventional transmissions. Development of an automatic, infinitely variable ratio, hydromechanical transmission, the Dual Mode Transmission, now gives the designer the opportunity to concentrate on developing engine power in the most efficient, lightest, smallest, and lowest cost manner, independent of vehicle requirements. Because of the DMT characteristics, vehicle performance is similar if either a free or a fixed turbine is used. Therefore, the fixed turbine now becomes a potential candidate for many vehicle applications. Still in the development and testing stage, the DMT is presently operating in several highway trucks.Copyright © 1969 by ASME

Ferrite phase shifter technology is reviewed. Particular emphasis is placed on discussion of nonreciprocal, toroidal waveguide phasers and dual mode reciprocal phasers for use in phased array antennas.

The microcomputer compensated crystal oscillator (MCXO) utilizes dual c-mode excitation of an SC-cut resonator for self-temperature sensing and compensation. The dual mode operation requires well-behaved fundamental and 3/sup rd/ overtone c-modes over the operating temperature range (e.g. -55/spl deg/C to +85/spl deg/C). The stability of MCXO depends primarily on the frequency vs. temperature hysteresis of the resonator. The hysteresis of the 10 MHz 3/sup rd/ overtone MCXO resonator has been a few parts in 10/sup 8/. This resonator is packaged in an HC-40 metal can, which makes the resonator the largest single component in the MCXO. The size of this resonator has limited efforts to reduce the size of the MCXO. In this paper, results of hysteresis measurements of a 20 MHz 3/sup rd/ overtone SC-cut resonator packaged in a TO-5 metal can (/spl sim/13% the volume and /spl sim/57% the height of the HC-40 package) is reported. Hysteresis over the -55/spl deg/C to +85/spl deg/C temperature range was found to be a few parts in 10/sup 8/, comparable to that of the 10 MHz 3/sup rd/ overtone resonator.

A double-octave S-Band TWT has been developed which delivers 450W CW and 900W Peak to a maximum duty of 25%, with small-signal gains of 26 and 32 dB and minimum efficiency levels of 21 and 23% in the CW and Pulsed modes of operation, respectively.

The dual mode optimal control problem to find a control u to minimize [email protected]!0~x'Qxdt subject to the constraints Q > 0, [email protected]? = Fx + gu, |u| =< 1, is solved for its ''singular'' solutions using well known quadratic regulator theory. The significance of the approach, apart from any due to its simplicity, is that it may be readily extended to handle cases when Q is positive semidefinite. It is also quite straightforward to extend the results to the time-varying multiple-input case.

A time-varying mathematical model of an oil-fired boiler unit, with estimated parameters, is used to represent a poorly defined multivariable physical process subjected to input disturbances and measurement noise.The model is simulated in discrete form and is used to generate on-line control action related to a quadratic performance criterion.A parameter-estimation technique is included in the overall control logic, based on a time-domain sensitivity analysis of the system-transition and -driving matrixes, and is used for continuously updating the model to the process system which is subjected to continuous change and random input disturbances.A form of predictive on—off and bounded linear control is included within the control programme to give suboptimal performance based on minimisation of a two-period and current-performance index, respectively. Relatively close model following and/or improved control can be obtained with inputs based on the model reference system, and some slight improvement in performance is possible using dual-mode control action.