Time-Dependent Effects on Parameters of Freight Demand Models

2011 ◽  
Vol 2224 (1) ◽  
pp. 42-50 ◽  
Author(s):  
José Holguín-Veras ◽  
Iván Sánchez ◽  
Carlos González-Calderón ◽  
Iván Sarmiento ◽  
Ellen Thorson
Keyword(s):  
Time Dependent ◽  
Demand Models ◽  
Freight Demand Models

Comparative Assessment of Industrial Classification Systems for Modeling Freight Production and Freight Trip Production

2019 ◽  
Vol 2673 (3) ◽  
pp. 210-224 ◽  
Author(s):  
Agnivesh Pani ◽  
Prasanta K. Sahu
Keyword(s):  
A Priori ◽  
Classification Systems ◽  
Model Systems ◽  
A Posteriori ◽  
Demand Model ◽  
Demand Models ◽  
Product Classification ◽  
Trip Production ◽  
Freight Demand Models ◽  
Better Than

Freight demand models typically employ a priori classification systems for dividing establishments into hypothetically complementary groups with homogeneous patterns in freight production (FP) and freight trip production (FTP). Although an attractive and popular notion, the assumption of homogeneity within these a priori industrial classes is reductive in nature and is not yet tested in literature. This research examines this hypothesis and explores the possibility of a data-driven segmentation by examining the relationships between FP/FTP patterns and prevalent a priori classes; subsequently, it creates homogeneous ensembles of a posteriori segments through aggregation. This research labels, explains, and interprets these novel segments using commodity value density of industrial classes. The alternate segmentation schemes are compared in their ability to predict FP and FTP and it is found that: (i) industrial classification systems (NAICS, ISIC) perform significantly better than product classification systems (ASICC); (ii) a considerable portion of variability in FTP does not depend on employment predictor due to the underlying influence of shipment size; (iii) an a posteriori segmentation scheme considering shipment size may represent an effective middle ground for developing both FP and FTP models in freight demand model systems. Adoption of these novel segments of the freight travel market has the potential to reduce the sample size requirements of freight demand model systems and minimize the financial necessities for future freight surveys.

scholarly journals Inventory models with integrated time dependent demands for deteriorating items – in third and fourth order equations.  

2021 ◽  
Author(s):  
Lalitha Ramachandran ◽  
Dr. Sivashankari C. K
Keyword(s):  
Visual Basic ◽  
Time Dependent ◽  
Inventory Models ◽  
Linear Quadratic ◽  
The Third ◽  
Demand Models ◽  
Optimum Order ◽  
Order Quantities ◽  
Order Intervals ◽  
Visual Basic 6.0

.  Inventory models with integrated time-dependent demands for deteriorative items are considered in this study.  The demand models found in the literature include constant, linear, quadratic, exponential, price dependent, and stock dependent among others.  To wit, no study exists that uses integrated time-dependent demands.  Three models are developed:  The first model uses continuously compounded demands, the second model uses linear demands integrated with continuously compounded demands, and the third model uses quadratic demands integrated with continuously compounded demands.  Mathematical models are delineated for each model and relevant examples are provided to elucidate the proposed procedure.  The objective herein is to obtain optimum order quantities and order intervals concerning the overall cost.  Sensitivity analysis is provided for each of the three models.  The necessary data was generated using Visual Basic 6.0..  Inventory models with integrated time-dependent demands for deteriorative items are considered in this study.  The demand models found in the literature include constant, linear, quadratic, exponential, price dependent, and stock dependent among others.  To wit, no study exists that uses integrated time-dependent demands.  Three models are developed:  The first model uses continuously compounded demands, the second model uses linear demands integrated with continuously compounded demands, and the third model uses quadratic demands integrated with continuously compounded demands.  Mathematical models are delineated for each model and relevant examples are provided to elucidate the proposed procedure.  The objective herein is to obtain optimum order quantities and order intervals concerning the overall cost.  Sensitivity analysis is provided for each of the three models.  The necessary data was generated using Visual Basic 6.0.

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