scholarly journals Studies in wave resistance: the effect of parallel middle body

1925 ◽  
Vol 108 (745) ◽  
pp. 77-92 ◽  
Keyword(s):  
Wave Length ◽  
Wave Resistance ◽  
Experimental Results ◽  
Transverse Waves ◽  
Wave Interference ◽  
Length Increase ◽  
Quarter Wave ◽  
Varying Length ◽  
The One ◽  
Remarkable Agreement

1. If a ship is altered by inserting different lengths of parallel middle body between the same bow and stern, the main features of the variation in the wave resistance may be inferred from the principle of wave interference, and may be expressed in terms of a certain length, sometimes called the wave­-making length of the ship. The problem proposed for examination is the alteration in this length with varying length of parallel middle body at the same speed, and, further, its variation for a given ship at different speeds. Recent discussions have attracted renewed attention to this problem. It may be said that there are two approximations based on experimental results of various kinds obtained from ship models. On the one hand the wave-making length is supposed to be approximately independent of speed for a given ship, and to increase directly with the increase of parallel middle body; on the other hand, an empirical formula which agrees with experimental results over a certain range makes the length increase with velocity, the increase being one-quarter of the increase in the wave-length of regular transverse waves. The following contribution to the solution of this problem is mathematical, and necessarily deals with a simplified form of ship. It is true that one cannot compare absolute values of the wave resistance with those of actual ship models; but it has been shown in former studies of the dependence of wave resistance on ship form that one obtains a rather remarkable agreement, at least in the character of the results and in the positions at which changes occur. Leaving detailed discussion of the present extension till later, it may be stated that as regards the two approximate formulæ mentioned above the results are intermediate; after an initial decrease the wave-making length increases until velocity, but not so rapidly as in the quarter wave-length formula.

Buckling Behavior of Tire Breaker Structure

1983 ◽  
Vol 11 (1) ◽  
pp. 3-19
Author(s):  
T. Akasaka ◽  
S. Yamazaki ◽  
K. Asano
Keyword(s):  
Elastic Foundation ◽  
Elastic Moduli ◽  
Wave Length ◽  
Bending Moment ◽  
Experimental Results ◽  
Automobile Tire ◽  
Buckling Behavior ◽  
Post Buckling ◽  
Steel Cord ◽  
Interlaminar Shear

Abstract The buckled wave length and the critical in-plane bending moment of laminated long composite strips of cord-reinforced rubber sheets on an elastic foundation is analyzed by Galerkin's method, with consideration of interlaminar shear deformation. An approximate formula for the wave length is given in terms of cord angle, elastic moduli of the constituent rubber and steel cord, and several structural dimensions. The calculated wave length for a 165SR13 automobile tire with steel breakers (belts) was very close to experimental results. An additional study was then conducted on the post-buckling behavior of a laminated biased composite beam on an elastic foundation. This beam is subjected to axial compression. The calculated relationship between the buckled wave rise and the compressive membrane force also agreed well with experimental results.

scholarly journals Divergent ⇒ complex amplitudes in two dimensional string theory

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Ashoke Sen
Keyword(s):  
Scattering Amplitudes ◽  
String Theory ◽  
Matrix Model ◽  
Two Dimensional ◽  
Full Matrix ◽  
Instanton Contribution ◽  
The Matrix ◽  
Theory Result ◽  
The One ◽  
Remarkable Agreement

Abstract In a recent paper, Balthazar, Rodriguez and Yin found remarkable agreement between the one instanton contribution to the scattering amplitudes of two dimensional string theory and those in the matrix model to the first subleading order. The comparison was carried out numerically by analytically continuing the external energies to imaginary values, since for real energies the string theory result diverges. We use insights from string field theory to give finite expressions for the string theory amplitudes for real energies. We also show analytically that the imaginary parts of the string theory amplitudes computed this way reproduce the full matrix model results for general scattering amplitudes involving multiple closed strings.

The English Crisis of 1297 in the Light of French Experience

1979 ◽  
Vol 18 (2) ◽  
pp. 1-13 ◽  
Author(s):  
Charles T. Wood
Keyword(s):  
Good Deal ◽  
The Political ◽  
English History ◽  
French Experience ◽  
Political Principle ◽  
The Many ◽  
The One ◽  
Remarkable Agreement ◽  
Edward I

Among the familiar sights crowding the landscape of English history from the dooms of Ine to that crown plucked from a hawthorn bush at Bosworth, none is more deeply cherished than the crisis of 1297 and the “Confirmation of the Charters” to which it gave rise. For, despite all the sharp differences over detail that the documentation for this crisis has engendered, scholars have shown remarkable agreement in seeing it as the one defeat suffered by Edward I in a long and notably successful reign. And to that defeat they have attributed great constitutional significance. Stubbs set the pattern, calling the “result singularly in harmony with what seems from history and experience to be the natural direction of English progress,” and Wilkinson is only one among the many who have recently elaborated on that theme:The crisis of 1297 … placed a definite check on the tendencies which Edward I had shown, to ignore the deep principles of the constitution under stress of the necessities which confronted the nation … It was a landmark in the advance of the knights … toward political maturity. It helped to establish the tradition of co-operation and political alliance between the knights and the magnates, on which a good deal of the political future of England was to depend …. What the opposition achieved, in 1297, was a great vindication of the ancient political principle of government by consent ….

Numerical investigation of the propagation of shock waves in rigid porous materials: development of the computer code and comparison with experimental results

1996 ◽  
Vol 324 ◽  
pp. 163-179 ◽  
Author(s):  
A. Levy ◽  
G. Ben-Dor ◽  
S. Sorek
Keyword(s):  
Porous Materials ◽  
Initial Conditions ◽  
Computer Code ◽  
Experimental Results ◽  
Numerical Code ◽  
Materials Development ◽  
Numerical Predictions ◽  
Wide Range ◽  
Dimensional Version ◽  
The One

The governing equations of the flow field which is obtained when a thermoelastic rigid porous medium is struck head-one by a shock wave are developed using the multiphase approach. The one-dimensional version of these equations is solved numerically using a TVD-based numerical code. The numerical predictions are compared to experimental results and good to excellent agreements are obtained for different porous materials and a wide range of initial conditions.

Natural Vulcanization Accelerators in Hevea Latex

1948 ◽  
Vol 21 (4) ◽  
pp. 853-859
Author(s):  
R. F. A. Altman
Keyword(s):  
Amino Acids ◽  
Experimental Results ◽  
The Other ◽  
Active Nitrogen ◽  
Nitrogen Bases ◽  
Other Hand ◽  
Decomposition Processes ◽  
Volatile Products ◽  
Nitrogenous Substances ◽  
The One

Abstract As numerous investigators have shown, some of the nonrubber components of Hevea latex have a decided accelerating action on the process of vulcanization. A survey of the literature on this subject points to the validity of certain general facts. 1. Among the nonrubber components of latex which have been investigated, certain nitrogenous bases appear to be most important for accelerating the rate of vulcanization. 2. These nitrogen bases apparently occur partly naturally in fresh latex, and partly as the result of putrefaction, heating, and other decomposition processes. 3. The nitrogen bases naturally present in fresh latex at later stages have been identified by Altman to be trigonelline, stachhydrine, betonicine, choline, methylamine, trimethylamine, and ammonia. These bases are markedly active in vulcanization, as will be seen in the section on experimental results. 4. The nitrogenous substances formed by the decomposition processes have only partly been identified, on the one hand as tetra- and pentamethylene diamine and some amino acids, on the other hand as alkaloids, proline, diamino acids, etc. 5. It has been generally accepted that these nitrogenous substances are derived from the proteins of the latex. 6. Decomposition appears to be connected with the formation of a considerable amount of acids. 7. The production of volatile nitrogen bases as a rule accompanies the decomposition processes. These volatile products have not been identified. 8. The active nitrogen bases, either already formed or derived from complex nitrogenous substances, seem to be soluble in water but only slightly soluble in acetone.

scholarly journals An attempt to determine the adiabatic relations of ethyl oxide

1897 ◽  
Vol 60 (359-367) ◽  
pp. 336-337 ◽  
Keyword(s):  
Wave Length ◽  
Experimental Results ◽  
Mathematical Discussion ◽  
Series Of Experiments

The wave-length of sound in gaseous and in liquid ethyl oxide (sulphuric ether) has been determined by the two first-mentioned of the authors, by means of Kundt’s method, between limits of temperature ranging from 100° C. to 200° C., and of pressure ranging from 4000 mm. to 31,000 mm. of mercury, and of volume ranging from 2·6 c. c, per gram to 71 c. c. per gram. Making use of the same apparatus throughout, the results obtained are to be regarded as comparative, and, by careful determination of the pitch of the tone transmitted through the gas, it is probable they are approximately absolute. The sections of the complete memoir deal with (I) a description of the apparatus employed, (II) the method of ascertaining the weights of ether used in each series of experiments, (III) determinations of the frequency of the vibrating rod, (IV) the calculations of the adiabatic elasticity and tables of the experimental results, and (V) a mathematical discussion of the results. The last section is due to Mr. Rose-Innes.

Grinding Performance of Porous Diamond Wheels on Different Materials

2011 ◽  
Vol 189-193 ◽  
pp. 3191-3197
Author(s):  
Qiu Lian Dai ◽  
Can Bin Luo ◽  
Fang Yi You
Keyword(s):  
Grain Size ◽  
Specific Energy ◽  
Experimental Results ◽  
Grinding Process ◽  
High Porosity ◽  
Grinding Forces ◽  
Abrasive Grain ◽  
Grinding Conditions ◽  
Medium Porosity ◽  
The One

In this paper, metal-bonded diamond wheels of different sized abrasive grain with different porosity were fabricated. Grinding experiments with these wheels on three kinds of materials were carried out under different grinding conditions. Experimental results revealed that wheel with high porosity (38%) had smaller grinding forces and specific energy than the one with a medium porosity (24%) on grinding G603. However, on grinding harder materials like Red granite or ceramics of Al2O3, the wheel with 38% porosity had bigger grinding forces and specific energy than the wheel with 24% porosity. Both wheels exhibited good self-sharpening capability during the grinding process of G603 and Red granite, but on grinding ceramics of Al2O3 the wheel with 38% porosity displayed in dull state during the grinding process . With the same porosity, the grinding forces of the wheel with a grain size of 230/270 US mesh were lower than the one with a grain size of W10 when grinding Red granite and ceramics of Al2O3. However revising results were obtained on grinding G603.

An LTCC Based Filter and Front End Module using Heterogeneous Dielectrics

2006 ◽  
Vol 3 (3) ◽  
pp. 129-135 ◽  
Author(s):  
Jun Chul Kim ◽  
Dongsu Kim ◽  
Hyun Min Cho ◽  
Jong Chul Park ◽  
Nam Kee Kang
Keyword(s):  
Power Amplifier ◽  
Bandpass Filter ◽  
Wave Length ◽  
Signal Delay ◽  
Ceramic Substrates ◽  
Front End ◽  
Quarter Wave ◽  
Front End Module ◽  
Signal Delay Time ◽  
Shunt Capacitor

This paper presents a multi-layered bandpass filter (BPF) and a power amplifier module (PAM) integrated with a SAW duplexer based on heterogeneous ceramic substrates. The heterogeneous substrates are composed of two different ceramic layers with εr = 7.4 and 17.5 in order to take advantage of their own properties. In the PAM substrate, a DC blocking capacitor and a shunt capacitor for an output matching network of a power amplifier are embedded with a material of εr = 17.5 to reduce occupied areas of the capacitors. On the other hand, a quarter-wave-length stripline and RF chokes are realized with a material of εr = 7.4 to reduce signal delay time. In the multi-layered BPF, a coupled stripline and a high shunt capacitor are embedded with materials of εr = 7.4 and 17.5, respectively, resulting in improved spurious characteristics.

Modeling Hydroplaning and Effects of Pavement Microtexture

2005 ◽  
Vol 1905 (1) ◽  
pp. 166-176 ◽  
Author(s):  
G. P. Ong ◽  
T. F. Fwa ◽  
J. Guo
Keyword(s):  
Three Dimensional ◽  
Flow Simulation ◽  
Experimental Results ◽  
Tire Pressure ◽  
Finite Volume Model ◽  
Proposed Model ◽  
Loss Of Contact ◽  
The One ◽  
Theoretical Considerations ◽  
Good Agreement

Hydroplaning on wet pavement occurs when a vehicle reaches a critical speed and causes a loss of contact between its tires and the pavement surface. This paper presents the development of a three-dimensional finite volume model that simulates the hydroplaning phenomenon. The theoretical considerations of the flow simulation model are described. The simulation results are in good agreement with the experimental results in the literature and with those obtained by the well-known hydroplaning equation of the National Aeronautics and Space Administration (NASA). The tire pressure–hydroplaning speed relationship predicted by the model is found to match well the one obtained with the NASA hydroplaning equation. Analyses of the results of the present study indicate that pavement microtexture in the 0.2- to 0.5-mm range can delay hydroplaning (i.e., raise the speed at which hydroplaning occurs). The paper also shows that the NASA hydroplaning equation provides a conservative estimate of the hydroplaning speed. The analyses in the present study indicate that when the microtexture of the pavement is considered, the hydroplaning speed predicted by the proposed model deviates from the speed predicted by the smooth surface relationship represented by the NASA hydroplaning equation. The discrepancies in hydroplaning speed are about 1% for a 0.1-mm microtexture depth and 22% for a 0.5-mm microtexture depth. The validity of the proposed model was verified by a check of the computed friction coefficient against the experimental results reported in the literature for pavement surfaces with known microtexture depths.

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