Author
Timothy L. Urban
Other affiliations: College of Business Administration
Bio: Timothy L. Urban is an academic researcher from University of Tulsa. The author has contributed to research in topics: Inventory control & Vehicle routing problem. The author has an hindex of 31, co-authored 55 publications receiving 2990 citations. Previous affiliations of Timothy L. Urban include College of Business Administration.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this article, a continuous, deterministic case of an inventory system in which the demand rate of an item is of a polynomial functional form, dependent on the inventory level is analyzed.
Abstract: This analysis is concerned with the continuous, deterministic case of an inventory system in which the demand rate of an item is of a polynomial functional form, dependent on the inventory level. Differential and integral calculus are used to find the inventory function with respect to time. From this, the objective function (to maximize average profit per unit time) is developed. For the continuous, multiperiod situation, a non-linear programming algorithm—separable programming—is utilized to determine the optimal order level (the quantity to order up to) and the order point (the quantity at which an order is placed). A numeric example and a sensitivity analysis are also presented.
384 citations
TL;DR: In this article, a greedy heuristic and a genetic algorithm are proposed for the solution to the integrated problem of inventory-level-dependent demand inventory model and product assortment and shelf-space allocation.
229 citations
TL;DR: A comprehensive overview of the literature on inventory control models in which the demand rate of an item is a function of the initial inventory level and those in which it is dependent on the instantaneous inventory level is presented.
223 citations
TL;DR: It is shown that neural networks significantly outperform regression models in situations with limited data availability and are compared to those of traditional econometric techniques.
Abstract: In this paper, an artificial neural network method is applied to forecast the end-of-year net asset value (NAV) of mutual funds. The back-propagation neural network is identified and explained. Historical economic information is used for the prediction of NAV data. The results of the forecasting are compared to those of traditional econometric techniques (i.e. linear and nonlinear regression analysis), and it is shown that neural networks significantly outperform regression models in situations with limited data availability.
170 citations
TL;DR: In this paper, an inventory system with an inventory-level-dependent demand rate followed by a constant demand rate was investigated, and the analysis previously conducted on this model imposed a terminal condition of zero inventory at the end of the order cycle.
Abstract: This paper investigates an inventory system with an inventory-level-dependent demand rate followed by a constant demand rate. The analysis previously conducted on this model imposed a terminal condition of zero inventory at the end of the order cycle. This condition is not warranted for systems with inventory-level-dependent demand rates, even for deterministic models. This paper relaxes this restriction, and an appropriate model is developed.
157 citations
Cited by
More filters
TL;DR: In this paper, the authors present a state-of-the-art survey of ANN applications in forecasting and provide a synthesis of published research in this area, insights on ANN modeling issues, and future research directions.
3,680 citations
01 Jan 2008
TL;DR: In this article, the authors argue that rational actors make their organizations increasingly similar as they try to change them, and describe three isomorphic processes-coercive, mimetic, and normative.
Abstract: What makes organizations so similar? We contend that the engine of rationalization and bureaucratization has moved from the competitive marketplace to the state and the professions. Once a set of organizations emerges as a field, a paradox arises: rational actors make their organizations increasingly similar as they try to change them. We describe three isomorphic processes-coercive, mimetic, and normative—leading to this outcome. We then specify hypotheses about the impact of resource centralization and dependency, goal ambiguity and technical uncertainty, and professionalization and structuration on isomorphic change. Finally, we suggest implications for theories of organizations and social change.
2,134 citations
TL;DR: Analysis of the experimental results proved that it is advantageous to apply SVMs to forecast financial time series because of the variability in performance with respect to the free parameters.
Abstract: This paper deals with the application of a novel neural network technique, support vector machine (SVM), in financial time series forecasting. The objective of this paper is to examine the feasibility of SVM in financial time series forecasting by comparing it with a multi-layer back-propagation (BP) neural network. Five real futures contracts that are collated from the Chicago Mercantile Market are used as the data sets. The experiment shows that SVM outperforms the BP neural network based on the criteria of normalized mean square error (NMSE), mean absolute error (MAE), directional symmetry (DS) and weighted directional symmetry (WDS). Since there is no structured way to choose the free parameters of SVMs, the variability in performance with respect to the free parameters is investigated in this study. Analysis of the experimental results proved that it is advantageous to apply SVMs to forecast financial time series.
1,104 citations
TL;DR: The developments in GALBP research is surveyed in order to describe and solve more realistic generalized problems (GALBP) and to survey the developments in assembly line balancing research.
1,020 citations
TL;DR: In this article, the authors extended the traditional economic production quantity model by accounting for imperfect quality items when using the EPQ/EOQ formulae, and considered the issue that poor-quality items are sold as a single batch by the end of the 100% screening process.
943 citations