The Characteristics of Certain Resisting Surfaces and Screws

1916 ◽  
Vol 20 (77) ◽  
pp. 3-9
Author(s):  
G. H. Bryan
Keyword(s):  
General Idea ◽  
General Character ◽  
Lateral Stability ◽  
Wind Gusts ◽  
The Stability ◽  
The Way

In the stability investigations which the late Captain Ferber published in the Revue d'Artillerie, the sustaining and other surfaces of an aeroplane were in certain cases taken to be represented, for dynamical purposes, by a system of three plane resisting laminæ fixed mutually at right angles. Unfortunately, however, such a system cannot in general be made equivalent to a collection of surfaces, such as those of an aeroplane, with the result that Captain Ferber's investigation failed to give the correct conditions of lateral stability. At the same time, Ferber's system of three orthogonal planes is so convenient, especially for forming a general idea of the effects of wind gusts on an aeroplane, that it is desirable to investigate conditions and limitations under which such a representation is valid. The desirability of a further investigation of the forces and couples acting on a system of resisting surfaces of a general character was foreshadowed in “Stability in Aviation,” and a more detailed discussion of the problem has now become necessary in order to prepare the way for further studies in the rigid dynamics of the motions of aeroplanes or of systems resembling them.

A Study of the Lateral Stability of Railroad Vehicles Using a Nonlinear Constrained Multibody Formulation

2001 ◽  
Author(s):  
Davide Valtorta ◽  
Khaled E. Zaazaa ◽  
Ahmed A. Shabana ◽  
Jalil R. Sany
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Linear Theory ◽  
Linear Stability Analysis ◽  
Numerical Study ◽  
Operating Conditions ◽  
Lateral Stability ◽  
Railroad Vehicles ◽  
Contact Formulation ◽  
The Stability

Abstract The lateral stability of railroad vehicles travelling on tangent tracks is one of the important problems that has been the subject of extensive research since the nineteenth century. Early detailed studies of this problem in the twentieth century are the work of Carter and Rocard on the stability of locomotives. The linear theory for the lateral stability analysis has been extensively used in the past and can give good results under certain operating conditions. In this paper, the results obtained using a linear stability analysis are compared with the results obtained using a general nonlinear multibody methodology. In the linear stability analysis, the sources of the instability are investigated using Liapunov’s linear theory and the eigenvalue analysis for a simple wheelset model on a tangent track. The effects of the stiffness of the primary and secondary suspensions on the stability results are investigated. The results obtained for the simple model using the linear approach are compared with the results obtained using a new nonlinear multibody based constrained wheel/rail contact formulation. This comparative numerical study can be used to validate the use of the constrained wheel/rail contact formulation in the study of lateral stability. Similar studies can be used in the future to define the limitations of the linear theory under general operating conditions.

Papacy, Crusade, and Christian-Muslim Relations

2018 ◽  
Keyword(s):  
Personal Experience ◽  
Religious Life ◽  
Trade Agreements ◽  
Muslim World ◽  
Peace Movements ◽  
The Stability ◽  
The Way ◽  
At Home

This book examines the role of the papacy and the crusade in the religious life of the late twelfth through late thirteenth centuries and beyond. Throughout the book, the contributors ask several important questions. Was Innocent III more theologian than lawyer-pope and how did his personal experience of earlier crusade campaigns inform his own vigorous promotion of the crusades? How did the outlook and policy of Honorius III differ from that of Innocent III in crucial areas including the promotion of multiple crusades (including the Fifth Crusade and the crusade of William of Montferrat) and how were both pope’s mindsets manifested in writings associated with them? What kind of men did Honorius III and Innocent III select to promote their plans for reform and crusade? How did the laity make their own mark on the crusade through participation in the peace movements which were so crucial to the stability in Europe essential for enabling crusaders to fulfill their vows abroad and through joining in the liturgical processions and prayers deemed essential for divine favor at home and abroad? Further essays explore the commemoration of crusade campaigns through the deliberate construction of physical and literary paths of remembrance. Yet while the enemy was often constructed in a deliberately polarizing fashion, did confessional differences really determine the way in which Latin crusaders and their descendants interacted with the Muslim world or did a more pragmatic position of ‘rough tolerance’ shape mundane activities including trade agreements and treaties?

On the causes of electoral volatility in Asia since 1948

2021 ◽  
pp. 135406882110468
Author(s):  
Don S Lee ◽  
Fernando Casal Bertoa
Keyword(s):  
Party Systems ◽  
Representative Democracy ◽  
Electoral Volatility ◽  
Essential Condition ◽  
Additional Finding ◽  
Healthy Functioning ◽  
The Stability ◽  
Detrimental Impact ◽  
Historical Legacies ◽  
The Way

Electoral stability has been viewed as an essential condition for the healthy functioning of representative democracy. However, there is little agreement in the literature about what shapes the stability of the electorate in general nor much attention paid to that of the Asian electorates in particular. We propose historical legacies, uniquely testable in Asia, as central determinants, but also test for conventional factors examined in other regions. By analyzing more than 150 elections in 19 post-WWII Asian democracies, we find that certain types of authoritarian (military or personalist) and colonial (non-British) legacies have a detrimental impact on the stabilization of the electorate, while some of the findings from other regions apply also to Asia. Our additional finding that such effects of historical legacies, particularly authoritarian interludes, are attenuated and cease to be significant with sufficient maturation of democracy, has important implications for the way party systems develop and democracies consolidate.

Vehicle Lateral Motion Control Based on Estimated Stability Regions

2017 ◽  
Author(s):  
Yiwen Huang ◽  
Yan Chen
Keyword(s):  
Measurement Errors ◽  
Local Stability ◽  
Stability Region ◽  
Control Method ◽  
Linearization Method ◽  
Stability Control ◽  
Lateral Stability ◽  
Shortest Distance ◽  
The Stability ◽  
Yaw Moment

This paper presents a novel vehicle lateral stability control method based on an estimated lateral stability region on the phase plane of vehicle yaw rate and lateral speed, which is obtained through a local linearization method. Since the estimated stability region does not only describe vehicle local stability, but also define the oversteering and understeering characteristics, the proposed control method can achieve both local stability and vehicle handling stability. Considering the irregular geometric shape of the estimated stability region, a stability analysis algorithm is designed to determine the distance between vehicle states and stability region boundaries. State estimation or measurement errors are also incorporated in the distance calculation. Based on the calculated shortest distance between vehicle states and stability boundaries, a direct yaw moment controller is designed to maintain vehicle states stay within the stability region. CarSim® and Simulink® co-simulation is applied to verify the control design through a cornering maneuver. The simulation results show that the proposed control method can make the vehicle stay within the stability region successfully and thus always operate in a safe manner.

scholarly journals Een geconstrueerd denken

1970 ◽  
Vol 61 ◽  
pp. 269-292
Author(s):  
Rajesh Heynickx
Keyword(s):  
Main Argument ◽  
Cultural Project ◽  
The Stability ◽  
Insight Into ◽  
The Way

In this article it is demonstrated that an analysis of how building metaphorswere used in the Flemish Catholic discourse of the interwar years can offermore insight into the way a community of believers tries to establish a culturalcohesiveness. The main argument is that in a period of deep transformations,building metaphors could become "instruments" for Catholics whowanted to defend and promote a traditional dimension of their religion.Building metaphors allowed Catholics to stress the stability of their own ideology(the fundaments) and to formulate their own cultural project (buildingplan). By analysing such strategic use of building metaphors in artistic andphilosophical discourses, it can become possible to shed more light on the roleneo-thomism, a main philosophical current in interwar Flanders, played inartistic debates and more specific in discussions on the modernisation of religiousart.

The Toccatas of Bach

1912 ◽  
Vol 39 ◽  
pp. 45-53
Author(s):  
J. A. Fuller-Maitland
Keyword(s):  
Recent Work ◽  
Good Reason ◽  
General Character ◽  
Valuable Book ◽  
The Way

There are no fewer than twelve complete works of Sebastian Bach to which the name Toccata is applied, and in nearly all cases the title seems to have come from the composer himself. It is always worth while to trace, if we can, the reasons which led a great man to choose one name rather than another for his creations; and in the case of Bach, I think we are justified in supposing that the names he gave were not purely arbitrary, but were chosen for some good reason. Certain modern composers, notably Brahms, have shown a strange indifference to the effect wrought by a well-chosen name for their music. His later works for pianoforte, often grouped under the heading of “Fantasias,” are divided into “Intermezzi” and “‘Capricci” according to whether they are slow movements or fast. But Bach, with his methodical habits, never showed that kind of almost perverse nonchalance in regard to the names his works were to bear. Remember the “Partitas,” and how each of the six introductory movements had a different designation from all the rest. As a matter of fact, there is not much indication of any inner variety of structure among the six, for all are preludial in general character, and it is evidently only a whim of the composer to give the six different titles. One of these, the sixth by the way, is styled “Toccata,” but has none of the distinguishing marks which, I hope to persuade you, Bach had in his mind when he used the title for independent compositions. Mr. Albert Schweitzer in his exceedingly valuable book on Bach (I am speaking of the recent work in two volumes, translated from the French by Mr. Ernest Newman) says that these Toccatas might just as well have been called Sonatas, or by any other name. Here I cannot agree with him, and the main object of my remarks on the present occasion.is to examine into the structure and style of the pieces, and see if we cannot discern some characteristic common to them all, and not shared by any other compositions of Bach.

Estimation of the Effect of a Parameter Change on the Roots of Stability Equations

1949 ◽  
Vol 1 (1) ◽  
pp. 39-58 ◽  
Author(s):  
K. Mitchell
Keyword(s):  
Secular Equation ◽  
Probable Error ◽  
Typical Case ◽  
Lateral Stability ◽  
Parameter Change ◽  
Longitudinal Stability ◽  
Quartic Equation ◽  
Spiral Motion ◽  
The Stability

SummaryA method is given for calculating approximately the changes in the roots of a stability secular equation caused by a change in any of the parameters involved. General formulas are given applicable to any quartic equation, and special formulae are also given applicable to the stability of an aeroplane: lateral stability in the text, and longitudinal stability in an appendix. The method of using the formulae is illustrated by applying them to a particular calculation of the lateral stability of an aeroplane, and a check of the results is made by comparing the predicted approximate changes with those calculated by solution of the modified period equations. It is shown that the formulae are reliable, for this typical case, for any reasonable changes in any parameter other than nv. If the changes in the derivatives are made equal to the probable error with which they can be measured, the formulae enable us to evaluate the probable errors of the roots. These are found to be considerable, and to arise mainly from uncertainties in yv, nv and nr: if these could be reduced to 0.03 in yv and 0.006 in the others, the uncertainties in the roots would be reduced to some ten per cent, of their values, except for a larger uncertainty in the root corresponding to the slow spiral motion.

Air Reconnaissance of Roman Scotland

Antiquity ◽  
1939 ◽  
Vol 13 (51) ◽  
pp. 280-292 ◽  
Author(s):  
O. G. S. Crawford
Keyword(s):  
Field Work ◽  
General Character ◽  
Roman Britain ◽  
Ordnance Survey ◽  
The Way

On 6 June I started from Southampton to carry out an investigation of the Roman roads and sites in Scotland from the air. For several years, as part of my official duties, I have been examining these on foot, in pursuance of a plan to publish a third edition of the Ordnance Survey Map of Roman Britain. It is intended to prepare the way for this map (which may be published on a slightly larger scale—10 miles instead of 16 miles to the inch) by the publication of maps of special regions on the scale of 4 miles to the inch. The drawing of the first two of these (Scotland, Sheet 3 [Forth and Tay], and Sheet I [The Border]) had been finished; but many doubtful points remained even after intensive field-work, and it seemed probable that a short air reconnaissance under favourable conditions would solve some of them. This opinion was amply justified by results. About a dozen new Roman sites (including as ‘ sites ’ new stretches of Roman road) were discovered; about 50 new sites in all, including many native forts, were placed on the map; and valuable results of a general character were obtained.

scholarly journals Antibubbles and fine cylindrical sheets of air

2015 ◽  
Vol 779 ◽  
pp. 87-115 ◽  
Author(s):  
D. Beilharz ◽  
A. Guyon ◽  
E. Q. Li ◽  
M.-J. Thoraval ◽  
S. T. Thoroddsen
Keyword(s):  
Layer Thickness ◽  
Stability Theory ◽  
Extended Period ◽  
Viscous Drops ◽  
Pool Surface ◽  
Lower Viscosity ◽  
Air Layers ◽  
The Stability ◽  
Air Film ◽  
The Way

Drops impacting at low velocities onto a pool surface can stretch out thin hemispherical sheets of air between the drop and the pool. These air sheets can remain intact until they reach submicron thicknesses, at which point they rupture to form a myriad of microbubbles. By impacting a higher-viscosity drop onto a lower-viscosity pool, we have explored new geometries of such air films. In this way we are able to maintain stable air layers which can wrap around the entire drop to form repeatable antibubbles, i.e. spherical air layers bounded by inner and outer liquid masses. Furthermore, for the most viscous drops they enter the pool trailing a viscous thread reaching all the way to the pinch-off nozzle. The air sheet can also wrap around this thread and remain stable over an extended period of time to form a cylindrical air sheet. We study the parameter regime where these structures appear and their subsequent breakup. The stability of these thin cylindrical air sheets is inconsistent with inviscid stability theory, suggesting stabilization by lubrication forces within the submicron air layer. We use interferometry to measure the air-layer thickness versus depth along the cylindrical air sheet and around the drop. The air film is thickest above the equator of the drop, but thinner below the drop and up along the air cylinder. Based on microbubble volumes, the thickness of the cylindrical air layer becomes less than 100 nm before it ruptures.

scholarly journals Cosmological bounce in Horndeski theory and beyond

2018 ◽  
Vol 191 ◽  
pp. 07013 ◽  
Author(s):  
R. Kolevatov ◽  
S. Mironov ◽  
V. Rubakov ◽  
N. Sukhov ◽  
V. Volkova
Keyword(s):  
General Relativity ◽  
Scalar Field ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Cosmological Solutions ◽  
The Stability ◽  
The Way

We discuss the stability of the classical bouncing solutions in the general Horndeski theory and beyond Horndeski theory. We restate the no-go theorem, showing that in the general Horndeski theory there are no spatially flat non-singular cosmological solutions which are stable during entire evolution. We show the way to evade the no-go in beyond Horndeski theory and give two specific examples of bouncing solutions, whose asymptotic past and future or both are described by General Relativity (GR) with a conventional massless scalar field. Both solutions are free of any pathologies at all times.

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