ITS Berkeley

Counteracting the Bullwhip Effect with Decentralized Negotiations and Advance Demand Information

Ouyang, Yanfeng
Daganzo, Carlos F.
2005

This paper shows how to reduce the bullwhip effect by introducing advance demand information (ADI) into the ordering schemes of supply chains. It quantifies the potential costs and benefits of ADI, and demonstrates that they are not evenly distributed across the chain. Therefore, market-based strategies to re-distribute wealth without penalizing any supplier are presented. The paper shows that if a centralized operation can eliminate the bullwhip effect and reduce total cost, then some of this reduction can also be achieved with decentralized negotiation schemes. Their performance is...

Moving Bottlenecks: A Numerical Method that Converges in Flows

Daganzo, Carlos F.
Laval, Jorge A.
2005

This paper presents a numerical method to model kinematic wave (KW) traffic streams containing slow vehicles. The slow vehicles are modeled discretely as moving boundaries that can affect the traffic stream. The proposed scheme converges in flows, densities and speeds without oscillations, and therefore can be readily used in situations where one wishes to model the effect of the traffic stream on the bottlenecks too.

Performance Comparison of Crane Double CyclingStrategies

Goodchild, Anne V.
Daganzo, Carlos F.
2005

This report compares the performance of three double-cycling algorithms used to determine the sequence with which to load and unload containers from a vessel with a quay crane. Double cycling is a technique which can improve the efficiency of a quay crane and container port by unloading and loading containers in the same crane cycle. The three algorithms, the greedy strategy, the proximal strategy, and Johnson’s rule, are introduced and results from applying the three strategies to a set of simulated vessels are compared. While Johnson’s rule provides the minimum number of cycles required...

A Variational Formulation of Kinematic Waves: Solution Methods

Daganzo, Carlos F.
2005

This paper presents improved solution methods for kinematic wave traffic problems with concave flow-density relations. As explained in part I of this work, the solution of a kinematic wave problem is a set of continuum least-cost paths in space-time. The least cost to reach a point is the vehicle number. The idea here consists in overlaying a dense but discrete network with appropriate costs in the solution region and then using a shortest-path algorithm to estimate vehicle numbers. With properly designed networks, this procedure is more accurate than existing methods and can be applied to...

Performance Comparison of Crane Double CyclingStrategies

Goodchild, Anne V.
Daganzo, Carlos F.
2005

This report compares the performance of three double-cycling algorithms used to determine the sequence with which to load and unload containers from a vessel with a quay crane. Double cycling is a technique which can improve the efficiency of a quay crane and container port by unloading and loading containers in the same crane cycle. The three algorithms, the greedy strategy, the proximal strategy, and Johnson’s rule, are introduced and results from applying the three strategies to a set of simulated vessels are compared. While Johnson’s rule provides the minimum number of cycles required...

Bullwhip Effect in Decentralized Supply Chains

Daganzo, Carlos F.
Ouyang, Yanfeng
2006

This paper analyzes the bullwhip effect in decentralized, linear and time-invariant (LTI) supply chains. It generalizes existing results by broadening the class of policies and customer demand processes under consideration. The supply chain is modeled as a single-input, single-output control system driven by arbitrary demands. The paper discusses the appropriateness of various metrics for the bullwhip effect, and derives analytical conditions to predict its presence independently of the demand process. The paper also gives a formula for the variance of the order stream at any stage...

Taming the Bullwhip Effect : From Traffic to Supply Chains

Ouyang, Yanfeng
Lago, Alejandro
Daganzo, Carlos F.
2006

Discretization and Validation of the Continuum Approximation Scheme for Terminal System Design

Ouyang, Yanfeng
Daganzo, Carlos F.
2006

This paper proposes an algorithm that automatically translates the “continuum approximation” (CA) recipes for location problems into discrete designs. It applies to terminal systems, but can also be used for other logistics problems. The study also systematically compares the logistics costs predicted by the CA approach with the actual costs for discrete designs obtained with the automated procedure. The predictions are quite accurate. The paper also gives conditions under which the discrete solution has a small optimality gap.

Lane-Changing in Traffic Streams

Laval, Jorge A.
Daganzo, Carlos F.
2006

It is postulated that lane-changing vehicles create voids in traffic streams, and that these voids reduce flow. This mechanism is described with a model that tracks lane changers precisely, as particles endowed with realistic mechanical properties. The model has four easy-to-measure parameters and reproduces without re-calibration two bottleneck phenomena previously thought to be unrelated: (i) the drop in the discharge rate of freeway bottlenecks when congestion begins, and (ii) the relation between the speed of a moving bottleneck and its capacity.

A Note on Asymptotic Formulae for One-Dimensional Network Flow Problems

Daganzo, Carlos F.
Smilowitz, Karen R.
2006

This note develops asymptotic formulae for single-commodity network flow problems with random inputs. The transportation linear programming problem (TLP) where N points lie in a region of R1 is one example. It is found that the average distance traveled by an item in the TLP increases with N1/2; i.e., the unit cost is unbounded when N and the length of the region are increased in a fixed ratio. Further, the optimum distance does not converge in probability to the average value. These one-dimensional results are a useful stepping stone toward a network theory for two and higher dimensions...