Block Signals Research Articles

Optimal Approximate Inverse of Linear Periodic Filters

We propose a method for constructing optimal causal approximate inverse for discrete-time single-input single-output (SISO) causal periodic filters in the presence of measurement noise. The analysis is based on block signals and multi-input multi-output (MIMO) time-invariant models for periodic filters. The objective function to be minimized is the asymptotic block mean square error. The optimization problem is formulated in terms of transfer matrices as an optimal model-matching problem with nonsquare model and plant. Based on an inner-outer factorization on the transpose of the plant rational matrix, it is shown that the problem can be further reduced to one with a lower dimensional square model and plant, which is then solved in the time-domain, and a closed-form solution is obtained. A lower bound on the objective function is given. It is shown that the lower bound can be asymptotically achieved as the order of the optimal transfer matrix increases. The proposed method is extended to MIMO periodic systems. Numerical examples are used to illustrate the performance of the proposed approximate inverse.

Blind identification with periodic modulation: a time-domain approach

We propose a method for blind identification of finite impulse response (FIR) channels with periodic modulation. The time-domain formulation in terms of block signals is simple compared with existing frequency-domain formulations. It is shown that the linear equations relating the products of channel coefficients and the autocorrelation matrix of the received signal can be further arranged into decoupled groups. The arrangement reduces computations and improves accuracy of the solution; it also leads to very simple identifiability conditions and a very natural formulation of the optimal modulating sequence selection problem. The proposed optimal selection minimizes the effects of channel noise and error in autocorrelation matrix estimation; it results in a consistent channel estimate when the channel noise is white. Simulation results show that the method yields good performance. It compares favorably with an existing subspace modulation-induced-cyclostationarity method, and it is robust with respect to channel order overestimation. The effect of modulation period and threshold of the modulating sequence are also discussed.

Combating the Collision Horror: The Interstate Commerce Commission and Automatic Train Control, 1900–1939

Combating the Collision Horror: The Interstate Commerce Commission and Automatic Train Control, 1900—1939 MARK ALDRICH This factor of humanjudgment is the factor which an automatic train stop is designed to eliminate. [Inter­ state Commerce Commission, 1922] The relative and not the intrinsic value of train control must be considered, and I am here to tell you that in my opinion, as a relative life saver it isn’t worth the money it costs. [Alexander Holley Rudd, 1926]' On the morning of January 12, 1919, New York Central train no. 17, the Wolverine, left Rochester for Buffalo at 2:54 a.m., an hour and thirty-one minutes late. It was traveling west on track 1 of four main tracks, all of which were protected with automatic block signals. At 3:35 it arrived at signal station 37, an interlocking plant that con­ trolled crossovers between the tracks. There the train stopped; engineman Gibbons informed the tower man that his locomotive was not steaming properly and asked for an engine. At 3:07 a.m., just thirteen minutes behind the Wolverine, train no. 11 operated by engineman Friedley also left Rochester for Buffalo on track 1. At 3:42 a.m., near South Byron, New York, it collided at about 50 miles per hour with the rear end of train no. 17. The impact knocked the Wolverine about 250 feet forward on the track and telescoped the rear Dr. Aldrich is professor of economics at Smith College. He would like to thank Dr. Michele Aldrich and the Technology and Culture referees for helpful comments on earlier drafts. Thanks are also due to Mr. Albert West of the Interstate Commerce Commission library for his assistance, and to Dr. Alan Leviton of the California Academy of Sciences for help with the figures. ‘Interstate Commerce Commission (ICC), “In the Matter of Automatic TrainControl Devices,” Report 69 (1922): 258—79, quote on 276; Alexander Holley Rudd, “Automatic Train Control,” Engineers and Engineering 43 (January 1926): 20-29, quote on 23 (emphasis in original). Rudd was the Pennsylvania Railroad’s chief signal engineer.© 1993 by the Society for the History of Technology. All rights reserved. 0040-165X/93/3401-0004$01.00 49 50 Mark Aldrich Fig. 1.—The wreck of the Wolverine at South Byron, New York, 1919. The Canfield, in which all the deaths occurred, has the Croton Falls telescoped inside it. (Interstate Commerce Commission, “Report of the Chief of the Bureau of Safety regarding Investigation of an Accident on the New York Central Railroad Near South Byron, New York on January 12, 1919,” in Accident Reports [Washington, D.C., 1920].) car, the Croton Falls, entirely through a Pullman named the Canfield (see fig. 1). Twenty-two people were killed—all in the Canfield—and seventy-one injured. The signal controlling entry into the block that train 17 occupied (the rear home signal) was approximately 3,400 feet east of train no. 17; a warning signal (the distant signal) for that block was nearly 5,000 feet east of the home signal. In spite of the protection from automatic block signals, engineman Gibbons whistled his flagman back to protect his train as the rules required. The flagman testified that he placed a torpedo (an explosive warning device) on the rails about twenty car lengths behind train 17, then continued back, dropping a flare and swinging a lantern when he was passed by train 11 about twenty-five lengths from his own train. How could train 11 have run a distant signal and a home signal and ignored the flagman’s warnings? Although engineman Friedley later swore that the signals showed green, they were in perfect working order and showing red immediately after the accident. Friedley had been without rest (but not on duty) for eighteen hours and probably fell asleep. He also testified that he saw no flagman or flare but did see lanterns on the ground about twelve telegraph poles distant. He thought that they The Interstate Commerce Commission and Automatic Train Control 51 were for track 3. He next saw the rear marker of the Wolverine and applied the brakes. Ten seconds later, the collision occurred. It was a cold night...

Variable bit rate video coding method

AbstractThe NUCLEI (Nagasaki University codec using large interframe prediction errors as important parts) method is proposed in this paper as a new interframe coding method for the asynchronous transfer model (ATM). Characteristics of this method are as follows: 1) interframe predictions are done using a full band, considering the high coding efficiency during the normal state; 2) interframe predictions are done even after cell loss, considering the high coding efficiency after cell loss; and 3) utilizing the fact that the small moving areas are less important than the large moving areas in dynamic images (motion pictures), large moving areas or blocks with large interframe differences are allocated to priority (higher priority) cells as priority blocks and comparatively small blocks are allocated to nonpriority (lower priority) cells as nonpriority blocks. These characteristics are realized by assigning frame memories for storing priority block signals in addition to frame memories storing all images. It is shown by computer simulations that good interframe coding characteristics can be realized in both during the normal state and after a cell loss.

Combating the Collision Horror: The Interstate Commerce Commission and Automatic Train Control, 1900-1939

On the morning of January 12, 1919, New York Central train no. 17, the Wolverine, left Rochester for Buffalo at 2:54 A.M., an hour and thirty-one minutes late. It was traveling west on track 1 of four main tracks, all of which were protected with automatic block signals. At 3:35 it arrived at signal station 37, an interlocking plant that controlled crossovers between the tracks. There the train stopped; engineman Gibbons informed the tower man that his locomotive was not steaming properly and asked for an engine. At 3:07 A.M., just thirteen minutes behind the Wolverine, train no. 11 operated by engineman Friedley also left Rochester for Buffalo on track 1. At 3:42 A.M., near South Byron, New York, it collided at about 50 miles per hour with the rear end of train no. 17. The impact knocked the Wolverine about 250 feet forward on the track and telescoped the rear

The block to transcription elongation is promoter dependent in normal and Burkitt's lymphoma c-myc alleles.

Aberrant c-myc expression patterns occur in human Burkitt's lymphoma cells, which consistently exhibit c-myc chromosomal translocations, mutations within and flanking the translocated allele, a loss of the block to transcription elongation in exon 1, and a promoter shift to use of the upstream P1 promoter. To define the mechanism responsible for the loss of transcription elongation blockage and resulting c-myc deregulation in Burkitt's lymphoma, we analyzed transcription patterns after transfer of normal and Burkitt's lymphoma c-myc alleles into murine cells and Xenopus oocyte germinal vesicles. We have determined that although the mutations within and surrounding several Burkitt's lymphoma c-myc alleles are not sufficient, in themselves, to abrogate the transcription elongation block, transcription initiation from the P2 promoter may be necessary to obtain the block to transcription elongation. To test directly the role of c-myc promoters in programming transcription elongation blockage, we analyzed transcription patterns from in vitro mutagenized c-myc genes containing deletions of either the P1 or P2 promoter. These data confirm that P1-initiated c-myc transcripts do not terminate at discrete sites near the 3' end of exon 1, whereas P2-initiated transcripts either terminate or read through the transcription block signals. Therefore, overexpression and/or constitutive expression from the c-myc P1 promoter may contribute to increased readthrough transcription in Burkitt's lymphoma cells and, hence, to aberrant expression patterns or levels of c-myc steady-state transcripts. In addition, the ability of normal cells to modulate c-myc P2-initiated transcription to either read through or to block elongation provides a fine control mechanism over c-myc steady-state RNA levels.

Railroad Signaling and Train Control

EFFICIENCY of train operation depends largely upon a system of directing train movements that will insure the maximum utilization of track and equipment capacity and the maximum output of train miles in a unit of time. In the earlier days the time interval method of railway signaling was favored, movements being directed by timetables and train orders. The space interval method is now universally recognized as most satisfactory, train movements being directed by block signals in addition to timetables and train orders. Block signals may be operated manually or automatically by means of a track circuit, the shunting of which by the trains operating upon the rails actuates the apparatus.

Railroad signaling and train control

EFFICIENCY of train operation depends largely upon a system of directing train movements that will insure the maximum utilization of track and equipment capacity and the maximum output of train miles in a unit of time. In the earlier days the time interval method of railway signaling was favored, movements being directed by timetables and train orders. The space interval method is now universally recognized as most satisfactory, train movements being directed by block signals in addition to timetables and train orders. Block signals may be operated manually or automatically by means of a track circuit, the shunting of which by the trains operating upon the rails actuates the apparatus.

Safety for Railroad Employes

FROM the day of the first successful locomotive, safety in operation has been the prime consideration in railroad location, design, construction and maintenance. The constant striving for more powerful engines, larger cars, heavier rails, stronger bridges, shorter routes, lower grades, fewer curves, clearer signals and better station facilities has resulted in providing not only for the more rapid handling of passengers and freight, but also for increased safety while in transit. The stories of the development of the air brake, automatic coupler, steel car, block signals, interlocking switch control, steel rail, steel wheel and many other well-known elements of modern railroad equipment would each provide material for an interesting treatise, but need only be mentioned here as examples of safety devices upon which millions of dollars, years of painstaking research and careful thought by the highest type of engineering minds have been and are being continually expended. But all the money invested in these improvements would have been wasted if it were not for the conscientious vigilance of the human beings using and directing them.

Track-circuit signaling on electrified roads

Railroads signals may be divided into three general classes according to their functions: (a) Those which confer rights on trains, or restrict their rights, known as train-order signals; (b) Those which designate the route a train is to take, and insure the safe condition of all switches and opposing signals on such route known as interlocking signals; (c) Those which are used primarily for properly spacing trains, known as block signals.

Discussion on “Electrically interlocking the block and mechanical signals on railways”

Discussion on “Electrically interlocking the block and mechanical signals on railways”

Electrically interlocking the block and mechanical signals on railways

Electrically interlocking the block and mechanical signals on railways