III. An experimental determination of the velocity of sound

1872 ◽  
Vol 20 (130-138) ◽  
pp. 34-35
Keyword(s):  
Experimental Determination ◽  
Cape Town ◽  
The Other ◽  
Velocity Of Sound ◽  
Successful Operation ◽  
Single Wire ◽  
Galvanic Current ◽  
Royal Observatory ◽  
Port Elizabeth

A galvanic current passes from the batteries at the Royal Observatory, Cape Town, at 1 o’clock, and discharges a gun at the Castle, and through relays drops a time-ball at Port Elizabeth. It appeared to the author that a valuable determination of the velocity of sound might be obtained by measuring upon the chronograph of the Observatory the interval between the time of the sound reaching some point near the gun and that of its arrival at the Observatory. As there is only a single wire between the Observatory and Cape Town, some little difficulty was experienced in making the necessary arrangements, without any interference with the 1 o’clock current to Port Elizabeth; but this difficulty was overcome by a plan which the author describes, and which was brought into successful operation on Feb. 27, 1871. The experiments could not have been carried out, on account of the encroachment they would have made on the time of the Observatory staff, had it not been for the assistance of J. Den, Esq., the acting manager of the Cape Telegraph Company, to whom the author is indebted for the preparation of a good earth-connexion near the gun, for permission to Mr. Kirby, a gentleman attached to the telegraph office, to assist in the experiments, and for a general superintendence of the arrangements at Cape Town. The observed times of hearing the sound were recorded on the chronograph by two observers, situated one (Mr. Kirby) at a distance of 641 feet from the gun, the other (Mr. Mann) at the Observatory, at a distance of 15,449 feet from the gun. The former distance was sufficient to allow the connexion of the main wire to be broken at the telegraph office after the gun had been fired, but before the sound reached the first observer.

scholarly journals I. An experimental determination of the velocity of sound

1872 ◽  
Vol 162 ◽  
pp. 1-6
Keyword(s):  
Experimental Determination ◽  
Velocity Of Sound ◽  
Galvanic Current ◽  
Dry Air ◽  
Cape Of Good Hope ◽  
Point Of Interest ◽  
Royal Observatory ◽  
Port Elizabeth ◽  
Mean Time

A galvanic current passes from the batteries at the Royal Observatory, Cape of Good Hope, at 1 o’clock, Cape mean time. This current discharges a gun at the Castle, and through relays drops a time-ball at Port Elizabeth. It appeared to me that a valuable determination of the velocity of sound might be obtained by measuring upon the chronograph of the Observatory the time between the sound reaching some point near the gun and that of its arrival at the Observatory. I thought also that it would be a point of interest to check, within the limits of our changes of temperature, the variations in the velocity of sound as dependent upon temperature, and to obtain some test of the applicability of the coefficient of expansion of dry air, as determined in cabinet experiments, to the mixture of air and water which would be the medium of the propagation of sound in our experiments.

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

scholarly journals XXII. On the extensive atmosphere of Mars

1831 ◽  
Vol 121 ◽  
pp. 417-422 ◽  
Keyword(s):  
The Other ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
Formed Part ◽  
The One

That several of the planets as well as that which we inhabit are surrounded by atmosphere, astronomical observations have long since established; the extent, however, to which in particular planets such atmospheres are diffused, is as yet not satisfactorily determined. The former rests principally upon phenomena observed on the planets’ discs, whilst the latter derives its support chiefly from those detected at or near their respective limbs. Every night, nay almost every hour, may give us indication of the one, whilst years are sometimes necessary, as in the case of planets unattended by satellites, to help us to the other; thus the hypothesis of the extensive atmosphere of Mars derives its origin from the observations of Cassini and Roëmer, and has stood more than a century and a half without refutation or support. The observations to which I allude formed part of a series undertaken for the determination of the parallax of Mars, and are recorded in the Mémoires de l’Académie des Sciences. Cassini’s were made at Briare and at La Charité sur Loire; whilst Roémer’s was obtained at the Royal Observatory of Paris.

Experimental Determination of the Mass Moment of Inertia of a Flywheel Using Dynamics and Statistical Methods

2015 ◽  
Author(s):  
Pezhman Hassanpour ◽  
Monica Weaser ◽  
Ray Colquhoun ◽  
Khaled Alghemlas ◽  
Abdullah Alrashdan
Keyword(s):  
Experimental Determination ◽  
Accurate Result ◽  
Moment Of Inertia ◽  
The Other ◽  
Experimental Measurements ◽  
Ball Bearings ◽  
Experiment Data ◽  
Mass Moment ◽  
Mass Moment Of Inertia

This paper presents the analysis of the mass moment of inertia (MMI) of a flywheel using experiment data. This analysis includes developing two models for determining the MMI of the flywheel. The first model considers the effect of mass moment of inertia only, while the second model takes the effect of friction in the ball bearings into consideration. The experiment results have been used along with both models to estimate the MMI of the flywheel. It has been demonstrated that while the model with no friction can be used for estimating the MMI to some extent, the model with friction produces the most accurate result. On the other hand, an effective application of the model with friction requires several experimental measurements using different standard masses. This translates into more expensive method in terms of experiment time and equipment cost.

Experimental Determination of the Cinematic Misfit within the Transmission of a 4x4 Vehicle that Leads to Self-Generated Torque along the Vehicle’s Inter-Axle Driveline

2014 ◽  
Vol 659 ◽  
pp. 262-267
Author(s):  
Marian Truta ◽  
Marin Marinescu ◽  
Octavian Alexa ◽  
Radu Vilau ◽  
Valentin Vinturis
Keyword(s):  
Experimental Determination ◽  
Experimental Methods ◽  
The Self ◽  
The Other ◽  
Other Hand ◽  
Theoretical Considerations ◽  
The Way

Present paper aims at revealing a way to determine the cinematic misfit within a 4x4 vehicle’s inter-axle driveline, which is eventually the reason of the self-generated torque occurrence. We used experimental methods to determine the magnitude of the cinematic misfit. Within this frame, we used a vehicle that has a longitudinal (inter-axle) differential and we locked it, actually forcing the longitudinal transmission to work without differentiating the angular speeds on its output shafts. On the other hand, the tire radii were different, inducing the above-mentioned cinematic misfit that we were looking for. We also present the way we fit the transducers on the vehicle’s driveline components to measure the needed parameters. The paper also presents some theoretical considerations regarding the occurrence of the cinematic misfit and its way of generating closed power loops within the vehicle’s transmission.

scholarly journals Experimental determination of the curvature-induced intra-wall polarization of inorganic nanotubes

Nanoscale ◽  
2021 ◽  
Author(s):  
Marie-Claire PIGNIE ◽  
Sabyasachi Patra ◽  
Lucie HUART ◽  
Aleksandar Milosavljevic ◽  
Jean-Philippe Renault ◽  
...  
Keyword(s):  
Experimental Determination ◽  
The Other ◽  
Inorganic Nanotubes

Inspired from a natural nano-mineral known as imogolite, aluminosilicate inorganic nanotubes are appealing systems for photocatalysis. One is completely hydrophilic (IMO-OH), while the other has a hydrophilic exterior and a...

scholarly journals Determination of the most appropriate bus rapid transit system for the eThekwini Municipal Area

2014 ◽  
Author(s):  
◽  
Emmanuel Olusegun Adewumi
Keyword(s):  
South Africa ◽  
Travel Time ◽  
Public Transport ◽  
Cape Town ◽  
Bus Rapid Transit ◽  
Successful Implementation ◽  
Rapid Transit ◽  
Transit System ◽  
Port Elizabeth

Invariably, a high percentage of the population of South Africa depends on public transport. In order to continue to satisfy commuters in terms of comfort, travel time, reliability of service and traffic congestion, there is a need to improve the efficiency of moving passengers to reduce travel time, delay time and number of stops. In the quest for advancement and improvement in public transport, many countries now embark on Bus Rapid Transit (BRT) systems based on the successful implementation of the system by cities like Curitiba (Brazil) and Bogota (Columbia). Government departments/transport authorities are often faced with the challenge of selecting the most suitable BRT system relative to the unique features of its transport demands and urban layout. Hence, this study proposes the determination of the most appropriate BRT system for the eThekwini Municipal Area (EMA). An in-depth literature review was conducted in order to determine the most adoptable BRT system amongst median, kerb side and segregated BRT systems, taking into consideration cost implications, safety of the passengers, pedestrian crossing, physically challenged commuters, vehicle option and manoeuvres. Physical assessment and critical review of the current operating BRT systems in Johannesburg, Cape Town and Port Elizabeth in South Africa was employed in this study as well as a critical comparison among these systems. The pros and cons of the three functional BRT systems in South Africa were stated and a way forward for EMA was recommended. Lastly, an assessment of the proposed BRT system in EMA was conducted on the existing Phase 1 and the remaining three phases. The review conducted was based on route inspection, access to property, factors considered in the selection of a BRT system, demand analyses of the routes and the evaluation of Johannesburg, Cape Town and Port Elizabeth BRT systems. Guidelines were also provided for the remaining proposed BRT routes which could be adopted by the eThekwini Transport Authority (ETA) in order to enhance a better performance in EMA over the three functional BRT systems in South Africa using the aforementioned criteria.

Experimental Determination of Spectral Transmittance of Porous Cerium Dioxide in the Range 900–1700 nm

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
Krithiga Ganesan ◽  
Wojciech Lipiński
Keyword(s):  
Experimental Determination ◽  
Spectral Range ◽  
Cerium Dioxide ◽  
The Other ◽  
Radiation Wavelength ◽  
Spectral Transmittance ◽  
Other Hand

Abstract Overall transmittance of porous cerium dioxide is measured in the spectral range of 900–1700 nm using dispersive spectroscopy. Dense and porous samples of cerium dioxide with average porosities of 0.08 and 0.72, respectively, are investigated. The transmittance of both sample types increases with decreasing thickness, and this trend is more pronounced for the dense samples. The on-average spectrally increasing transmittance of the dense samples is attributed to the decreasing absorption by bulk cerium dioxide with radiation wavelength. The transmittance of the porous samples, on the other hand, remains approximately constant over the spectrum. Porous samples attenuate radiation stronger than the dense samples at any wavelength in the considered range, and it is hypothesized that this effect is due to more intense scattering. Sharp local variations of the transmittance are observed for both sample types.

Experimental Determination of Axial Viscoelasticity of Braided Steel Cables Through the Design of a Special Purpose Machine

2019 ◽  
Author(s):  
Diego A. Zamora-Garcia ◽  
Luis Miguel Acosta-Carrion ◽  
Ma. Pilar Corona-Lira ◽  
Alejandro C. Ramirez-Reivich
Keyword(s):  
Free Vibration ◽  
Experimental Determination ◽  
Test Bench ◽  
Viscoelastic Behavior ◽  
Axial Direction ◽  
The Other ◽  
Effective Length ◽  
Essential Idea ◽  
Steel Cables

Abstract Braided steel cables have the potential for improving the mechanisms providing them several advantages in comparison with rigid elements. Nevertheless, a limitation in the use of cable mechanism is that due to the inherent flexibility, the problem of vibration arises. In this research, we investigate the axial viscoelastic behavior of 1/32″ braided steel cables. The essential idea is to determine the parameters of elasticity (k) and viscosity (b) as a function of the length of the cable in its axial direction. It was achieved through the design and construction of a test bench and the design of an experiment. The test bench is a free vibration particular design machine. One end of the cable is fixed to the structure, and in the other end, a load is attached. Then, the load is released, and the free vibration of the cable in the axial direction is registered. The factor of the experiment is the length of the cable. There are six levels, and these were repeated four times. We demonstrated that the braided steel cables have a viscoelastic behavior like a Kelvin-Voigt. Also, we found a relation between the effective length of the cables and the parameters of elasticity and viscosity.

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