scholarly journals Non-linear optimization for continuous travel demand estimation

2021 ◽  
Vol 17 (1) ◽  
pp. 40-46
Author(s):  
Anastasiya P. Raevskaya ◽  
◽  
Alexander Y. Krylatov ◽  
Keyword(s):  
Traffic Flow ◽  
Road Network ◽  
Optimization Problem ◽  
Travel Demand ◽  
Linear Optimization ◽  
Demand Estimation ◽  
Theory And Practice ◽  
Traffic Distribution ◽  
Non Linear ◽  
Fresh Perspective

Models and methods of traffic distribution are being developed by researchers all over the world. The development of this scientific field contributes to both theory and practice. In this article, the non-linear optimization of traffic flow re-assignment is examined in order to solve continuously the travel demand estimation problem. An approach has been developed in the form of computational methodology to cope with the network optimization problem. A uniqueness theorem is proved for a certain type of road network. Explicit relations between travel demand and traffic flow are obtained for a single-commodity network of non-intersecting routes with special polynomial travel time functions. The obtained findings contribute to the theory and provide a fresh perspective on the problem for transportation engineers.

scholarly journals Algebraic Bayesian network: non-linear optimization problem in local posteriori inference with atomic stochastic evidence

2014 ◽  
Vol 1 (20) ◽  
pp. 200
Author(s):  
Alexander Vladimirovich Sirotkin ◽  
Valeriya Fuatovna Musina ◽  
Alexander Lvovich Tulupyev
Keyword(s):  
Bayesian Network ◽  
Optimization Problem ◽  
Linear Optimization ◽  
Linear Optimization Problem ◽  
Non Linear

Analytical Reason for Smaller Lateral Sway in Angled-Plane Scissor Linkage

2020 ◽  
Vol 12 (5) ◽  
Author(s):  
Sunil Kumar Singh ◽  
Sangamesh R. Deepak
Keyword(s):  
Rigid Body ◽  
Optimization Problem ◽  
Linear Optimization ◽  
Parallel Plane ◽  
Design Parameters ◽  
Finite Limit ◽  
Constrained Optimization Problem ◽  
Linear Optimization Problem ◽  
Non Linear ◽  
Linear Constrained Optimization

Abstract Scissor linkages are widely used with scissor links arranged in two parallel planes. When small misalignment of revolute joint axes are permissible, the linkage can undergo lateral sway. This paper, using rigid-body kinematics and a modeling of misalignment, converts the task of finding lateral sway into a non-linear constrained optimization problem. Through linearization of the optimization problem, this paper analytically proves that (1) maximum lateral sway increases as the number of units in the parallel-plane scissor linkage increases whereas in angled-plane scissor linkage, the lateral sway tends to a finite limit as the number of units is increased and (2) the lateral sway is independent of connector length in parallel-plane scissor linkage whereas it is dependent on the length of the connector in angled-plane scissor linkage. These results are further substantiated with numerical solution of the non-linear optimization problem. The results imply that the angled-plane scissor linkage can substantially limit lateral sway in comparison to parallel-plane scissor linkage under similar conditions of joint misalignment. The analytical expression derived in this paper helps in identifying the influence of design parameters on lateral sway.

Optimal Deployment of Cordon Sanitaire with Available Testing Capacity

2021 ◽  
pp. 036119812110556
Author(s):  
Hongzhi Lin ◽  
Yongping Zhang
Keyword(s):  
Traffic Flow ◽  
Waiting Time ◽  
Road Network ◽  
Travel Demand ◽  
Nonlinear Integer Programming ◽  
Network Equilibrium ◽  
Level Model ◽  
Optimal Deployment ◽  
Upper Level ◽  
Cordon Sanitaire

During the COVID-19 pandemic, authorities in many places have implemented various countermeasures, including setting up a cordon sanitaire to restrict population movement. This paper proposes a bi-level programming model to deploy a limited number of parallel checkpoints at each entry link around the cordon sanitaire to achieve a minimum total waiting time for all travelers. At the lower level, it is a transportation network equilibrium with queuing for a fixed travel demand and given road network. The feedback process between trip distribution and trip assignment results in the predicted waiting time and traffic flow for each entry link. For the lower-level model, the method of successive averages is used to achieve a network equilibrium with queuing for any given allocation decision from the upper level, and the reduced gradient algorithm is used for traffic assignment with queuing. At the upper level, it is a queuing network optimization model. The objective is the minimization of the system’s total waiting time, which can be derived from the predicted traffic flow and queuing delay time at each entry link from the lower-level model. Since it is a nonlinear integer programming problem that is hard to solve, a genetic algorithm with elite strategy is designed. An experimental study using the Nguyen-Dupuis road network shows that the proposed methods effectively find a good heuristic optimal solution. Together with the findings from two additional sensitivity tests, the proposed methods are beneficial for policymakers to determine the optimal deployment of cordon sanitaire given limited resources.

scholarly journals Travel Demand Estimation in Urban Road Networks as Inverse Traffic Assignment Problem

2021 ◽  
Vol 22 (3) ◽  
pp. 287-300
Author(s):  
A. Krylatov ◽  
A. Raevskaya ◽  
V. Zakharov
Keyword(s):  
Road Network ◽  
Travel Demand ◽  
Traffic Assignment ◽  
Computational Study ◽  
Demand Estimation ◽  
Absolute Difference ◽  
Actual Problem ◽  
Optimization Program ◽  
Urban Road ◽  
High Urgency

Abstract Nowadays, traffic engineers employ a variety of intelligent tools for decision support in the field of transportation planning and management. However, not a one available tool is useful without precise travel demand information which is actually the key input data in simulation models used for traffic prediction in urban road areas. Thus, it is no wonder that the problem of estimation of travel demand values between intersections in a road network is a challenge of high urgency. The present paper is devoted to this urgent problem and investigates its properties from computational and mathematical perspectives. We rigorously define the travel demand estimation problem as directly inverse to traffic assignment in a form of a bi-level optimization program avoiding usage of any pre-given (a priori) information on trips. The computational study of the obtained optimization program demonstrates that generally it has no clear descent direction, while the mathematical study advances our understanding on rigor existence and uniqueness conditions of its solution. We prove that once a traffic engineer recognizes the travel demand locations, then their values in the road network can be found uniquely. On the contrary, we discover a non-continuous dependence between the travel demand locations and absolute difference of observed and modeled traffic values. Therefore, the results of the present paper reveal that the actual problem to be solved when dealing with travel demand estimation is the problem of recognition of travel demand locations. The obtained findings contribute in the theory of travel demand estimation and give fresh managerial insights for traffic engineers.

Four-bar motion generation with elasticity constraints and optimization

2009 ◽  
Vol 223 (3) ◽  
pp. 245-253
Author(s):  
Y M Al-Smadi ◽  
K Russell ◽  
R S Sodhi
Keyword(s):  
Optimization Problem ◽  
Search Algorithm ◽  
Linear Optimization ◽  
Motion Generation ◽  
Linear Optimization Problem ◽  
Transmission Angle ◽  
Non Linear ◽  
Transverse Deflection ◽  
Static Torque ◽  
Motion Generator

In conventional planar four-bar motion generation, all mechanism links are assumed rigid or non-deforming. Although the assumption of link rigidity in kinematic synthesis may be generally appropriate and often practiced, a statically loaded planar four-bar mechanism will undergo a degree of elastic deflection, particularly the crank and follower links. In this work, a non-linear optimization problem is formulated for planar four-bar motion generation that considers an applied coupler force and corresponding crank static torque, crank transverse deflection, and follower buckling. The output from the non-linear optimization problem – mechanism fixed and moving pivot loci – are input for a search algorithm that down selects a mechanism solution that satisfies transmission angle conditions, Grashof conditions, and a mechanism compactness condition. The final output of the presented method is planar four-bar motion generator that approximates prescribed coupler poses with satisfactory crank deflection and without follower buckling and also satisfies conditions for link rotatability, transmission angle and compactness.

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