A Dynamic Model of Presidential Nomination Campaigns

1980 ◽  
Vol 74 (3) ◽  
pp. 651-669 ◽  
Author(s):  
John H. Aldrich
Keyword(s):  
Mathematical Model ◽  
Difference Equation ◽  
Dynamic Model ◽  
Equation Model ◽  
Electoral Success ◽  
Presidential Nomination ◽  
Dynamic Forces ◽  
Selection Of

Recent campaigns have demonstrated the importance of dynamic elements in affecting the selection of presidential nominees. This paper develops a mathematical model to analyze these dynamics. The heart of the model is the assumed relationship between the ability to acquire resources and success in primaries and caucuses. The expenditure of resources leads to greater electoral success, while greater electoral success (in particular, exceeding expectations in a primary or caucus) leads to greater resource-gathering capabilities. A difference equation model of these relationships is proposed. I prove that any campaign of this form is necessarily unstable, which implies that most candidates will be “winnowed out” necessarily, while only a very few, but at least one candidate, will necessarily “have momentum.” This result is true whether there are two or many contenders. However, I also argue that the larger the number of candidates, the stronger the dynamic forces, and thus the more rapid the “winnowing out” process.

The Dynamics of Urban Spatial Structure: Some Exploratory Results Using Difference Equations and Bifurcation Theory

1981 ◽  
Vol 13 (12) ◽  
pp. 1473-1483 ◽  
Author(s):  
M Clarke ◽  
A G Wilson
Keyword(s):  
Difference Equation ◽  
Spatial Structure ◽  
Dynamic Model ◽  
Difference Equations ◽  
Bifurcation Theory ◽  
Equation Model ◽  
Urban Spatial Structure ◽  
Hypothetical System ◽  
Simple Difference ◽  
Bifurcation Behaviour

It is demonstrated that a simple difference equation model, which exhibits complex bifurcation behaviour, can be used to represent change in urban retailing and residential systems. These submodels are combined to form a rudimentary dynamic model of urban spatial structure. A sample of exploratory results are presented for a 169-zone hypothetical system.

A difference equation model of partial series

1994 ◽  
Vol 61 (2-3) ◽  
pp. 301-305
Author(s):  
K.J. Bunch ◽  
R.W. Grow
Keyword(s):  
Difference Equation ◽  
Equation Model

DIFFERENTIAL EQUATIONS FOR TRAIN STARTING WITH ELASTIC CONNECTIONS

2021 ◽  
Vol 2 ◽  
pp. 18-26
Author(s):  
I.P. POPOV
Keyword(s):  
Mathematical Model ◽  
Differential Equations ◽  
Friction Force ◽  
Static Friction ◽  
Longitudinal Vibrations ◽  
Maximum Tension ◽  
Inert Mass ◽  
The Moment ◽  
Elastic Couplings ◽  
Selection Of

The starting mode for the train is the most difficult. An effective method of pulling is the selection of coupling clearances. In this case, the cars are set in motion sequentially and the inert mass, as well as the static friction force immediately at the moment of starting, are minimal. This method has two significant drawbacks - a small fixed value of the gaps in the couplings and the shock nature of the impulse transfer. These disadvantages can be avoided by using elastically deformable couplings. The aim of this work is to construct a mathematical model of "easy" starting of a train with elastic couplings. The softening of the train start-off mode is essentially due to the replacement of the simultaneous start-off of the sections with alternate ones. To exclude longitudinal vibrations of the composition, after reaching the maximum tension of the coupling, the possibility of its harmonic compression should be mechanically blocked.

scholarly journals Analysis of the Modified Construction of the Column Mechanism MacPherson

2018 ◽  
Vol 19 (11) ◽  
pp. 41-44
Author(s):  
Marek Kwietniewski ◽  
Tadeusz Bil
Keyword(s):  
Mathematical Model ◽  
Steering Wheel ◽  
Passenger Cars ◽  
Proper Selection ◽  
Front Suspension ◽  
Change Of Direction ◽  
Partial Elimination ◽  
Selection Of

The McPherson column name comes from the inventor of this Earle S. MacPherson solution, which was first manufactured at the Ford plant in 1949. This is one of the most commonly used types of front suspension in popular passenger cars. The advantage of this type of suspension is a compact construction, but the disadvantage is. The influence of the damping motion on the position of the steering wheel may result in an unintentional change of direction of travel. At the same time, there is a slight additional tilt of the wheels when the "spring" movement. In the proposed solution, partial elimination of this type of incorrectness is proposed by changing the type of connection of the steering rod end to the steering wheels of the vehicle. The introduced change consists in replacing one of the spherical joints in these joints into two rotary joints. Such a change introduces a mathematical model describing the behavior of the suspension under the influence of the depreciation of additional parameters. Proper selection of these parameters allows for significant reduction of unnecessary direction changes during driving. The described model of the structure of the mechanism allows to analyze the influence of all its dimensions on the selected parameters of the behavior of the wheels during the ride, resulting from the movement of the suspension and steering.

Lagrangian Integro-Difference Equation Model for Precipitation Nowcasting

2021 ◽  
Author(s):  
Seppo Pulkkinen ◽  
V. Chandrasekar ◽  
Tero Niemi
Keyword(s):  
Difference Equation ◽  
Urban Areas ◽  
Short Range ◽  
Autoregressive Process ◽  
Skill Score ◽  
Equation Model ◽  
Validation Dataset ◽  
Time Range ◽  
Stochastic Perturbations ◽  
Second Best

AbstractDelivering reliable nowcasts (short-range forecasts) of severe rainfall and the resulting flash floods is important in densely populated urban areas. The conventional method is advection-based extrapolation of radar echoes. However, during rapidly evolving convective rainfall this so-called Lagrangian persistence (LP) approach is limited to deterministic and very short-range nowcasts. To address these limitations in the one-hour time range, a novel extension of LP, called Lagrangian INtegro-Difference equation model withAutoregression (LINDA), is proposed. The model consists of five components: 1) identification of rain cells, 2) advection, 3) autoregressive process describing growth and decay of the cells, 4) convolution describing loss of predictability at small scales and 5) stochastic perturbations to simulate forecast uncertainty. Advection is separated from the other components that are applied in the Lagrangian coordinates. The reliability of LINDA is evaluated using the NEXRAD WSR-88D radar that covers the Dallas-Fort Worth metropolitan area, as well as the NEXRAD mosaic covering the continental United States. This is done with two different configurations: LINDA-D for deterministic and LINDA-P for probabilistic nowcasts. The validation dataset consists of 11 rainfall events during 2018-2020. For predicting moderate to heavy rainfall (5-20 mm/h), LINDA outperforms the previously proposed LP-based approaches. The most significant improvement is seen for the ETS and POD statistics with the 5 mm/h threshold. For 30-minute nowcasts, they show 15% and 16% increase, respectively, to the second-best method and 48% and 34% increase compared to LP. For the 5 mm/h threshold, the increase in the ROC skill score of 30-minute nowcasts from the second-best method is 10%.

The envelope method in the problem of choosing a rational composition of measuring instruments

2021 ◽  
pp. 68-72
Author(s):  
Il'ya A. Meshchikhin ◽  
Sergej S. Gavryushin
Keyword(s):  
Mathematical Model ◽  
Monitoring Systems ◽  
Measuring Instruments ◽  
Key Points ◽  
Envelope Method ◽  
Loaded State ◽  
The Mathematical Model ◽  
Selection Of ◽  
Rational Composition

As part of the development of monitoring systems for the operation of technical objects, the problem of improving the quality of monitoring systems for the loaded state is considered. Based on the analysis of the mathematical model of the structure and its loading, a methodology for the selection of measuring instruments was developed. The urgency of the problem of calculating substantiation of the choice of key points of the structure is shown, at which it is possible to measure deformations for the subsequent restoration of the existing loads with maximum accuracy. An approach based on the envelope method for determining the rational composition of measuring instruments for restoring the loads acting on the structure is stated.

Аpplication of the mathematical model of human torso for modeling abbreval influence in wound ballistics

2020 ◽  
Vol 22 (3) ◽  
pp. 132-139
Author(s):  
A. V. Denisov ◽  
M. D. Stepanov ◽  
N. A. Haraldin ◽  
A. V. Stepanov ◽  
A. I. Borovkov ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Element Model ◽  
Mechanical Action ◽  
Calculation Model ◽  
Calculation Results ◽  
Automated Processing ◽  
Original Calculation ◽  
Using Data ◽  
The Mathematical Model ◽  
Selection Of

Abstract. In the work, a review of scientific articles on the behavior of tissues and organs of the human body under local mechanical effects on it, as well as a description of the physico-mechanical properties of biological materials. The selection of mechanical behavior for each biological material as part of a mathematical model of the human torso was carried out, its finite element model was created, validation experiments were modeled using data presented in the literature. An original calculation model of a human torso with a tuned interaction of organs with each other was developed. Contact interaction parameters are determined. The developed computational model of a human torso was verified based on data from open sources for an experiment with mechanical action by a cylindrical impactor. An algorithm for processing pressure and acceleration graphs has been implemented in order to obtain tolerance curves. A specialized modular program has been created for the automated processing of calculation results and the output of the main results. 42 numerical tests were carried out simulating the entry of a steel ball into each of 21 zones for power engineers of 40 and 80 J. According to the results of the tests for each organ, pressure and acceleration tolerance curves were obtained, animations of the behavior of organs under shock were created, visualization of the pressure field propagation in organs was obtained torso.

Simulation Investigations of Influence of Tooth Depth Coefficient on Dynamic Phenomena in Toothed Gear

2016 ◽  
Vol 817 ◽  
pp. 41-46
Author(s):  
Grzegorz Peruń
Keyword(s):  
Dynamic Model ◽  
Point Of View ◽  
General Level ◽  
Theoretical Point ◽  
Gear Pair ◽  
Contact Ratio ◽  
Dynamic Forces ◽  
Toothed Gears ◽  
Dynamic Phenomena

The increase of transverse contact ratio (εα) value usually allows reducing general level of gear vibroactivity. Article put to the test influence of coefficient εα value on dynamic forces in mesh zone with use of dynamic model of toothed gear. From theoretical point of view, the optimum value of transverse contact ratio is equal 2, what mean, that in mesh are always two pair of teeth. Obtainment such value of coefficient εα requires another construction of toothed wheels – wheels with HCR (High Contact Ratio) profile teeth. On result of occurrence of different deviations in toothed gears, as well as the dynamic phenomena, obtainment of continuous two-pair cooperation of gear pair is impossible and when this necessary is, solutions with near or exceed optimum value of coefficient are applied.

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