Truck Performance on Argentinean Highways

1996 ◽  
Vol 1555 (1) ◽  
pp. 114-123 ◽  
Author(s):  
Adrián Ricardo Archilla ◽  
Arístides Osvaldo Fernández de Cieza
Keyword(s):  
Field Data ◽  
The United States ◽  
Force Balance ◽  
Power Ratio ◽  
Ratio Distribution ◽  
Performance Curves ◽  
National Highway ◽  
Acceleration And Deceleration ◽  
Speed Prediction ◽  
Force Balance Equation

Truck performance observed on grades on National Highway 7 in Argentina is described. The observed weight-to-power ratio distribution in Argentina is shown to be considerably higher than that in North America. Also, a speed prediction model based on the simple force balance equation is fitted to the field data. The model explains about 80 percent of the observed variation, and for steep upgrades the predictions are similar to values observed in the United States. Acceleration and deceleration performance curves are also given. Finally, a validation of the model is presented by comparing the predicted and the observed speed profiles along two upgrades for trucks of known weight-to-power ratios. The shapes of the speed profiles predicted by the model closely replicate the observed speed profiles.

Static Determinacy in the Theory of Finite Width Foil Bearings

1974 ◽  
Vol 41 (1) ◽  
pp. 51-54 ◽  
Author(s):  
W. E. Langlois
Keyword(s):  
Force Balance ◽  
Finite Width ◽  
Foil Bearings ◽  
Lubrication Equation ◽  
Foil Bearing ◽  
Edge Conditions ◽  
Single Force ◽  
Static Determinacy ◽  
Force Balance Equation ◽  
Determinate Problem

The assumption of “perfect flexibility” is shown to be self-consistent in an important class of finite-width foil bearing problems. When the membrane equations are written in the “stretched coordinates” of foil bearing theory, the usual edge conditions on the tape result in a statically determinate problem. The tape dynamics couples to the Reynolds lubrication equation through a single force-balance equation which does not entail the elastic strain.

Numerical Investigation of the Combined Effects of Biomolecular Adsorption and Microdroplet Evaporation on the Performance of the Electrocapillary-Based Digital Microfluidic Systems

2011 ◽  
Author(s):  
Ali Ahmadi ◽  
Mina Hoorfar
Keyword(s):  
Mass Loss ◽  
Protein Concentration ◽  
Adsorption Rate ◽  
Force Balance ◽  
Combined Effects ◽  
Microfluidic Systems ◽  
Gibbs Equation ◽  
Rate Effects ◽  
Digital Microfluidic ◽  
Force Balance Equation

In this article, microdroplet motion in the electrocapillary-based digital microfluidic systems is modeled accurately, and the combined effects of the biomolecular adsorption and micro-droplet evaporation on the performance of the device are investigated. An electrohydrodynamic approach is used to model the driving and resisting forces, and Fick’s law and Gibbs equation are used to calculate the microdroplet evaporation and adsorption rate. Effects of the adsorption and evaporation rates are then implemented into the microdroplet dynamics by adding new terms into the force balance equation. It is shown that mass loss due to the evaporation tends to increase the protein concentration, and on the other hand, the increased concentration due to the mass loss increases the biomolecular adsorption rate which has a reverse effect on the concentration. The modeling results indicate that evaporation and adsorption play crucial roles in the microdroplet dynamics.

Use of Laboratory and Field Data to Evaluate the Pier Scour Equation from Hydraulic Engineering Circular 18

2017 ◽  
Vol 2638 (1) ◽  
pp. 113-121
Author(s):  
Stephen T. Benedict ◽  
Thomas P. Knight
Keyword(s):  
South Carolina ◽  
Field Data ◽  
Field Measurements ◽  
The United States ◽  
Prediction Equation ◽  
Hydraulic Engineering ◽  
Bridge Engineering ◽  
Geological Survey ◽  
Pier Scour ◽  
Primary Focus

The Hydraulic Engineering Circular 18 (HEC-18) pier scour prediction equation is the most widely used pier scour prediction equation in the United States, if not the world, and understanding the equation’s performance is of interest to the bridge engineering community. Previous evaluations of the equation’s performance were limited to smaller sets of laboratory and field data. In 2014, the U.S. Geological Survey, in cooperation with the South Carolina Department of Transportation, published a U.S. Geological Survey pier scour database, consisting of 569 laboratory and 1,858 field measurements of pier scour. This extensive database is a valuable resource for evaluating the HEC-18 pier scour equation, which is the primary focus of the investigation presented in this paper. Although comparing predicted and measured values is a common method for evaluating the performance of a prediction equation, the present investigation used a different approach and evaluated the HEC-18 equation by comparing selected data from the USGS database with the dimensionless relationship used to develop the original equation. This alternative approach highlighted some of the strengths and weaknesses of the equation, which are not as evident in the more common approach of comparing predicted and measured values. The findings of the investigation are presented in this paper.

Effect of Body Lateral Extension Upon the Elastic Contact

2009 ◽  
Author(s):  
Marilena Glovnea ◽  
Emanuel Diaconescu
Keyword(s):  
Half Space ◽  
Outer Radius ◽  
Force Balance ◽  
Contact Theory ◽  
Contact Radius ◽  
Elastic Contact ◽  
Space Theory ◽  
Lateral Extension ◽  
Load Direction ◽  
Force Balance Equation

Half-space contact theory cannot be applied when either contacting bodies are thin or they possess small transversal dimensions. The former situation is often dealt with, but the latter seems to be neglected. This paper investigates the effect of outer radius of cylindrical bodies upon the contact stress field. The method consists in adding supplementary displacements and stresses to the half-space solution in order to fulfill the boundary conditions and the force balance equation on load direction. It is found that the half-space theory is applicable if transversal radius exceeds contact radius.

Cervical Spine Tolerance to Catastrophic Injury in Rollover Crash Environments

2009 ◽  
Author(s):  
Donald S. Burke ◽  
Martha W. Bidez ◽  
Kathryn Mergl
Keyword(s):  
Traffic Safety ◽  
The United States ◽  
Fatality Rate ◽  
Passenger Vehicle ◽  
Highway Traffic ◽  
National Highway Traffic Safety ◽  
Catastrophic Injury ◽  
National Highway ◽  
Serious Injuries ◽  
Rollover Crash

According to the National Highway Traffic Safety Administration (NHTSA) rollovers have a higher fatality rate than all other kinds of crash modes. Of the 6,159,287 police reported crashes in 2005 in the United States, only 4.1% involved a rollover. Yet, rollovers accounted for 34.4% (10,816) of all passenger vehicle fatalities and another 149,406 individuals sustained serious injuries in rollover crashes in 2005 [5].

Simulation Approach to Traffic Noise Modeling: American Automobile Manufacturers Association Community Noise Model Version 4.0

1997 ◽  
Vol 1601 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Roger L. Wayson ◽  
John M. MacDonald ◽  
Ronald Eaglin ◽  
Barbara Wendling
Keyword(s):  
Simulation Model ◽  
Traffic Noise ◽  
The United States ◽  
Point Sources ◽  
Noise Model ◽  
Community Noise ◽  
Model Free ◽  
Sound Levels ◽  
Acceleration And Deceleration ◽  
Interrupted Flow

Several models are available for predicting traffic noise levels. The FHWA-promulgated model, STAMINA 2.0, is the most widely used noise model in the United States and is used to model free-flow vehicular traffic. STAMINA 2.0 cannot directly model interrupted-flow traffic. Sound levels from interrupted-flow traffic can be approximated with STAMINA 2.0 using the method presented in NCHRP Report 311. This method is time-consuming and difficult to use. These limitations demonstrate the need for a traffic noise model that can model the acceleration and deceleration behavior of interrupted-flow traffic. The University of Central Florida has developed the American Automobile Manufacturers Association Community Noise Model (CNM). The CNM is a traffic simulation model that determines sound levels at receivers by modeling vehicles as discrete moving point sources. The vehicle energy is determined from acceleration, deceleration, idle, and cruise reference energy mean emission level curves. Sound energy attenuation is calculated from distance, ground absorption, and user input barriers. The model sums the energy at receivers from all vehicles and then calculates the Leq noise level at the receivers. It is demonstrated that the CNM predicts receiver Leq levels that are very close to STAMINA 2.0 results for constant-speed traffic. The CNM can also accurately predict sound levels at receivers located before and after intersections. In addition to the advantages of a real simulation model, the CNM is user friendly, allowing the user to place lanes and receivers using the mouse.

Speed-Profile Model for Two-Lane Rural Highways

2000 ◽  
Vol 1737 (1) ◽  
pp. 42-49 ◽  
Author(s):  
Kay Fitzpatrick ◽  
Jon M. Collins
Keyword(s):  
Highway Safety ◽  
Geometric Features ◽  
Speed Profile ◽  
Model Design ◽  
Rural Highways ◽  
Profile Model ◽  
Safety Design ◽  
Acceleration And Deceleration ◽  
Speed Prediction ◽  
Design Consistency

Design consistency refers to highway geometry’s conformance with driver expectancy. Generally, drivers make fewer errors at geometric features that conform with their expectations. A proposed method for evaluating design consistency is to predict the speed along an alignment by using a speed-profile model. A speed-profile model was developed by using the following: speed prediction equations that calculate the expected speed at horizontal, vertical, or combination curves; assumed desired speed for the roadway; TWOPAS equations that determine the performance-limited speeds at every point; acceleration and deceleration rates; and several documented assumptions. The speed-profile model can be used to evaluate the design consistency of a facility or to generate a speed profile along an alignment. In conclusion, the speed-profile model developed appears to provide a suitable basis for the Interactive Highway Safety Design Model design consistency module.

Debris Effects on EHL Contact

2000 ◽  
Vol 122 (4) ◽  
pp. 711-720 ◽  
Author(s):  
Young S. Kang ◽  
Farshid Sadeghi ◽  
Xiaolan Ai
Keyword(s):  
Film Thickness ◽  
Reynolds Equation ◽  
Elastohydrodynamic Lubrication ◽  
Force Balance ◽  
Time Dependent ◽  
Elasticity Equations ◽  
Minimum Film Thickness ◽  
Bounding Surfaces ◽  
Force Balance Equation ◽  
Ehl Contact

A model was developed to study the effects of a rigid debris on elastohydrodynamic lubrication of rolling/sliding contacts. In order to achieve the objectives the time dependent Reynolds equation was modified to include the effects of an ellipsoidal shaped debris. The modified time dependent Reynolds and elasticity equations were simultaneously solved to determine the pressure and film thickness in EHL contacts. The debris force balance equation was solved to determine the debris velocity. The model was then used to obtain results for a variety of loads, speeds, and debris sizes. The results indicate that the debris has a significant effect on the pressure distribution and causes a dent on the rolling/sliding bounding surfaces. Depending on the size and location of the debris the pressure generated within the contact can be high enough to plastically deform the bounding surfaces. Debris smaller than the minimum film thickness do not enter the contact and only large and more spherical debris move toward the contact. [S0742-4787(11)00501-7]

scholarly journals Force balance in current sheets in collisionless plasma

2021 ◽  
Vol 7 (2) ◽  
pp. 11-21
Author(s):  
Oleg Mingalev ◽  
Pavel Setsko ◽  
Mikhail Melnik ◽  
Igor Mingalev ◽  
Helmi Malova ◽  
...  
Keyword(s):  
Current Sheet ◽  
Balance Equation ◽  
Normal Component ◽  
Collisionless Plasma ◽  
Force Balance ◽  
One Dimensional ◽  
Current Sheets ◽  
First Time ◽  
The Magnetic Field ◽  
Force Balance Equation

In this paper, we derive a divergent form of the force balance equation for collisionless plasma in the quasineutrality approximation, in which the electric field and current density are excluded. For a stationary spatially one-dimensional current sheet with a constant normal component of the magnetic field and magnetized electrons, the general form of the force balance equation has been obtained for the first time in the form of a conservation law. An equation in this form is necessary for the correct formulation of boundary conditions when modeling asymmetric current sheets, as well as for the control of the stationarity of the numerical solution obtained in the model. Furthermore, the fulfillment of this equation is considered for two types of stationary configurations of a thin current sheet, which are obtained using a numerical model. The derived equation makes it possible to develop models of asymmetric current sheets, in particular current sheets on the magnetopause flanks in the magnetotail.

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