Enrique R. Venta

Finding optimal line balances with OptPack

This paper describes OptPack, a new algorithm for finding optimal solutions to assembly line balancing problems. Preliminary computational experience shows that the algorithm is significantly faster, on the benchmark literature problems, than Johnsons (1988) Fable, the fastest currently available algorithm. A microcomputer implementation of OptPack is also described and computational experience is reported.

Using neural networks to aid the diagnosis of breast implant rupture

Abstract From a database consisting of 78 inplants that were surgically removed, ultrasound findings and surgical results were used to train and test backpropagation and radial basis function (RBF) neural networks using the round-robin or leave-one-out method. Receiver-operating-characteristic (ROC) curve analysis was applied to compare the performance of the different neural networks with that of the radiologists involved in the ultrasound evaluations. The neural networks outperformed the radiologists involved. RBF networks performed better in this classification problem than did backpropagation networks. The best performing network utilized, in addition to the findings, the (unaided) diagnosis of the radiologist. Thus, the ‘team’ approach appears to provide the best results. Also, the network performed particularly well in those cases in which the radiologist classified the implant as indeterminate. The results suggest that a neural network using findings extracted from sonograms by experienced sonographers can be of great assistance to physicians with the diagnosis of implant rupture.

An upper bound on the number of cuts needed in Gomory's method of integer forms

The cut discipline of Gomorys first finiteness proof for the method of integer forms is used to derive an upper bound on the number of cuts required to obtain solution to pure integer programs.

Facility location on a grid with a diagonal line

This article extends the traditional median problem on a grid to include a diagonal line (e.g., a street). In contrast to the traditional median problem, this generalized problem is nonconvex and nonseparable, invalidating some of the properties on which well-known median-seeking algorithms are based. This work presents an algorithm for finding the median on this generalized grid and discusses the relationship between it and the traditional median.