Fog Signals Research Articles

Extreme, Outrageous, and (Un)reliable: Navigating Uncertainty in the Development of Sound-Based Fog Signals in Scotland, 1860-1900.

This case study demonstrates how an analysis grounded in sound studies, rather than visual studies, reveals a different technological outcome in the development of coastal navigation systems. In the late nineteenth century, engineers at Scotland's Northern Lighthouse Board developed and managed a growing network of sound-based fog signals, primarily using steam-powered sirens. Despite the prevailing perception that sound signaling was more unreliable and risky than lighthouses for coastal navigation, engineers focused on maximizing the loudness of these devices to address the uncertainty of sound transmission. By prioritizing the siren and narrowing the system's goals to warning sailors about imminent danger, the engineers created a system with fundamentally different aims, implementation methods, and design priorities than those of visually-based lighthouse technology. This sound-based analysis uncovers how sensory hierarchies shaped technological decisions, leading to a unique and distinct approach to coastal navigation.

Recognition of freezing of gait in Parkinson’s disease based on combined wearable sensors

Freezing of gait is a common gait disorder among patients with advanced Parkinson’s disease and is associated with falls. This paper designed the relevant experimental procedures to obtain FoG signals from PD patients. Accelerometers, gyroscopes, and force sensing resistor sensors were placed on the lower body of patients. On this basis, the research on the optimal feature extraction method, sensor configuration, and feature quantity selection in the FoG detection process is carried out. Thirteen typical features consisting of time domain, frequency domain and statistical features were extracted from the sensor signals. Firstly, we used the analysis of variance (ANOVA) to select features through comparing the effectiveness of two feature selection methods. Secondly, we evaluated the detection effects with different combinations of sensors to get the best sensors configuration. Finally, we selected the optimal features to construct FoG recognition model based on random forest. After comprehensive consideration of factors such as detection performance, cost, and actual deployment requirements, the 35 features obtained from the left shank gyro and accelerometer, and 78.39% sensitivity, 91.66% specificity, 88.09% accuracy, 77.58% precision and 77.98% f-score were achieved. This objective FoG recognition method has high recognition accuracy, which will be helpful for early FoG symptoms screening and treatment.

Center Line Coordinates Survey for Existing Railway by 3-D Constraints Method

Since the maintenance of HSR depends both on inner geometries and outer geometries information of track, it’s necessary that the survey technologies could measure the smoothness and coordinates of track in a high-density manner. But the existing technologies for track survey are either inaccurate or inefficient for HSR maintenance, the problem about track survey arises with the rapid development of high-speed rail (HSR) in China. To meet the demands on track smoothness survey of existing line, a method denoted as 3-D Constraints Method is introduced in this paper. The general principle of the method is obtaining center line locus with location information by means of survey trolley and CP-Ⅲ stakes. By measuring the distances between trolley and CP-Ⅲ stakes, the boundary condition could be determined. So, the problem of center line calculation is transformed into the problem of definite integral for FOG signals. Accordingly, an algorithm of coordinate calculation is given. With the constraints form CP-Ⅲ stakes, the coordinates of center line could be obtained in a defined accuracy. Finally, the simulation result shows that the method is effective. DOI: http://dx.doi.org/10.11591/telkomnika.v11i5.2556 Keywords 3-D Constraints Method; Maintenance Benchmark; Track Geometries Measuring Trolley; Center Line Survey Full Text: PDF

Intra-annual variation in the stable oxygen and carbon isotope ratios of cellulose in tree rings of coast redwood (Sequoia sempervirens)

Fog is a seasonally variable hydrologic input to coast redwood ( Sequoia sempervirens, D. Don) ecosystems with a stable isotopic composition (δ 18O, δ2H) that is distinct from rainfall. The intra-annual variation in tree ring cellulose δ18O of coast redwood was measured to determine what portion of the tree ring should be sampled to best target fog signals. Ten years of rings were subdivided into ten equal units for three trees at two sites in northern California. Intra-annual variation in cellulose δ18O was as high as 3‰ with a consistent pattern of enriched (in 18O) values from the annual ring boundary and depleted values from the central portion of the ring. These patterns show a strong coherence between replicate trees at the same site as well as significant correlations between individuals at sites over 250 km apart. Intra-annual variation in stable carbon isotope ratios (δ13C) was as high as 2‰ and produced a pattern with depleted (in 13C) values from the ring boundary and enriched values from the central portion of the ring. Although these δ13C patterns were not as strongly correlated between replicate trees as the patterns in δ18O variation, they did produce significant correlations with the variation in fog frequencies recorded at local airports. This study highlights the importance of quantifying intra-annual variation in tree ring stable isotope signals as a guide to further investigations on historic variability from long chronologies especially if the signal of interest is seasonally variable (eg, fog).

海上における霧中信号について

海上における霧中信号について

Defining the Close-Quarters Situation at Sea

The International Regulations for Preventing Collisions at Sea contain several important terms which are open to different interpretations such as ‘safe speed’, ‘close-quarters situation’ and ‘risk of collision’. It is not possible to give exact definitions of these terms as some of the factors involved are difficult to quantify but there is little doubt that mariners would welcome some official guidance on their application.The following paper by Dr Hilgert proposes a method of defining ‘close-quarters situation’ in terms of the principal factors which apply. The method is of particular interest because it is actually used by the maritime administration of one government and has been submitted to the International Maritime Organization for consideration. The IMO Sub-Committee on Safety of Navigation has taken note of the suggested approach and has invited comments.It is suggested in the paper that a simplified version of close-quarters situation could be determined in terms of the quantifiable parameters of speed, manoeuvrability and angle of approach. The method could be used to establish minimum values of a close-quarters situation but other factors would have to be taken into account such as the close presence of navigational hazards or other vessels, radar performance including the effect of errors and the desirability of keeping out of audible range of the fog signals of an approaching vessel.Despite some obvious limitations the method serves to indicate the least values which should be used and the paper contributes to a better understanding of this aspect of the avoidance of collision at sea.

Sound reflections in and under oceans

Modern oceanography is founded on the curiosity and interest of the naturalist with a bent for things marine who, in pursuing understanding of plants and animals of the oceans, has appreciated the need for comparable understanding of their physical and chemical environment. It is also founded on the interest of the physicist who from time to time has been called in to help provide for a human need: to sound ocean depths for laying cables, to make more reliable fog signals, or to avoid icebergs or deal with submarines. Some of the latter have become interested in the oceans or in the physics of the earth beneath for their own sake. No matter what their individual background, main physicists have found fascination in the science of the ocean.

Some recent developments in marine navigational aids

The paper describes recent developments in the operation of the older types of navigational aids, lights, fog signals and radio beacons. A novel system of remote control is described and means for automatic operation of remote light stations discussed. Development of a system to give automatic indication of locally reduced visibility is described. A method of employing arc discharge lamps as navigation lights is mentioned. A new system for coding radio beacons is described. A policy for electrical power supplies at remote places is outlined, mention being made of the possible use of solar energy.

Some micrometeorological measurements in ocean fog

Introduction. Audible fog signals are extensively used as aids to navigation during periods of low visibility. Their performance has frequently been less than satisfactory. To gain a better understanding of the propagation of audible sound over ocean waters in fog an experimental study was undertaken which included, in addition to extensive acoustical measurements, a series of micrometeorological measurements in fog.

Sound Propagation over Ocean Waters in Fog

Audible fog signals are extensively used as aids to marine navigation during periods of low visibility. Performance, however, has frequently been inadequate. To obtain better understanding of the physics of sound propagation over water in fog, a series of field experiments was carried out off the coast of Maine. Signals in the frequency range between about 200 and 2000 cps were employed to measure sound attenuation for distances up to a few miles. Simultaneous micrometeorological measurements were performed to describe the relevant properties of the lowest layers of the atmosphere through which the sound was propagated. This paper describes briefly the measurement techniques used and presents typical samples of the results obtained. Downwind, the average excess attenuation over and above inverse square law can be accounted for principally by molecular absorption. Upwind, large values of excess attenuation were found due to shadow zone formation. This constitutes a severe limitation of the useful range of audible fog signals. Fog itself contributes little to the average excess attenuation.

Fog Signals

Measurements have recently been made in cooperation with the Lighthouse Service on a number of different types of fog signals at Cape Henry. These measurements indicate that air borne sounds, as now produced, will never give adequate protection to shipping. A large number of observations were made by a number of observers on relative loudness of different types of signals. The relative loudness was also determined by matching with a Western Electric 2 A Audiometer. Making use of the curve worked out by Fletcher relating loudness to loudness level in decibels, the loudness level as determined with the aid of the audiometer has been converted into loudness and compared with the average value obtained by the various observers.

Marconi's Wireless Pilot

DURING the last two decades, experiments have been made on wireless fog beacons, one of which is known as the revolving beam and another as the rotating loop. Navigators are not fully satisfied with these forms of fog signals, neither do the signals give a direct lead of sufficient reliability into a port. The Marchese Marconi s latest wireless invention recently demonstrated in Italy to a party of guests representing shipping and scientific interests of Britain and Italy definitely supplies this need.

Radio Fog Signals for the Protection of Navigation; Recent Progress

Radio Fog Signals for the Protection of Navigation; Recent Progress

Audible electric signals in industrial plants, and acoustical engineering

The paper is a plea for a wider use of acoustic signals in industrial plants. It is shown that much time is wasted by the officials, experts, and important employees in trying to locate each other. With loud acoustic signals installed throughout a plant, in the shops, yards, and offices, it becomes possible to locate any of a considerable number of men instantly, using a simple code call for each. Such calls could be given only imperfectly by pushing a button, and for this reason a special code calling instrument has been developed, which closes electric contacts automatically, after having been set for a desired combination. The actual conditions and the needs for acoustic signals are discussed in application to steel mills, shipyards, textile mills, printing establishments, coal mines, construction jobs, etc. It is shown that in addition to code calls, audible signals and particularly electric horns are used with advantage as extensions to telephone bells in noisy places, and also as warning signals for various purposes. The general scope of the forthcoming art of acoustic engineering is then discussed, and its importance is shown in design of theaters, churches, and large auditoriums; also in the installation of fog signals. The problem of measurement of sound intensity is then taken up and the available means and devices are described. It is also shown that sound waves may be directly photographed under proper conditions and the laws of their propagation studied. Attention is called to the importance of experimental and theoretical study of the modes of vibrations of diaphragms used in acoustic devices.

Analysis of photographs of fog signals obtained with the phonodeik : D. C. Miller. ( Trans. Royal Society of Canada, March, 1919.)

Analysis of photographs of fog signals obtained with the phonodeik : D. C. Miller. ( Trans. Royal Society of Canada, March, 1919.)

Fog signals.―Areas of silence and greatest range of sound

The experience of Trinity House in regard to the audibility of sound signals has brought to notice the fact that on occasions the sound may be heard near the source and again at a considerable distance, while inaudible between these positions. This was first observed, or at least prominently brought forward, by Prof. Tyndall. The statement was regarded with some scepticism by scientific men at the time, but the explanation of the effect of wind on sound given by Prof. G. Stokes will, with a little amplification, suffice also for the silent areas. Stokes in this explanation (which was repeated by Henry and by Osborne Reynolds) points out that the speed of the wind, in consequence of the surface friction of the ground, increases with the height, and that since the velocity of second is constant not with reference to the ground, but to the air through which the sound travels, the front of a plane wave vertical at some given instant will subsequently lean backwards if travelling against the wind, and forwards if with the wind. Or, in other words, the sound tends to leave the ground in the first case and to cling to it in the second.

Experiments at St. Catherine's with Fog Signals

Experiments at St. Catherine's with Fog Signals

Coast Fog Signals

Coast Fog Signals

On the Audibility of Fog Signals at Sea

IN NATURE of August 8, attention was called to some recent investigations, published in Hansa, on the inaudibility of fog-horns at sea within certain zones surrounding the signal, although the horn is distinctly heard outside of such regions. It seems strange to me that I can find nowhere suggested that this may be a phenomenon of interference similar to that suggested in light by Dr. Lloyd of Dublin (Trans. Roy. Irish Acad., vol. xvii.).

The Relation of the Sounds of Fog Signals to Other Sounds

The Relation of the Sounds of Fog Signals to Other Sounds