Novel fuzzy-based optimization approaches for the prediction of ultimate axial load of circular concrete-filled steel tubes

An accurate estimation of the axial compression capacity of the concrete-filled steel tubular (CFST) column is crucial for ensuring the safety of structures containing them and preventing related failures. In this article, two novel hybrid fuzzy systems (FS) were used to create a new framework for estimating the axial compression capacity of circular CCFST columns. In the hybrid models, differential evolution (DE) and firefly algorithm (FFA) techniques are employed in order to obtain the optimal membership functions of the base FS model. To train the models with the new hybrid techniques, i.e., FS-DE and FS-FFA, a substantial library of 410 experimental tests was compiled from openly available literature sources. The new model\u2019s robustness and accuracy was assessed using a variety of statistical criteria both for model development and for model validation. The novel FS-FFA and FS-DE models were able to improve the prediction capacity of the base model by 9.68% and 6.58%, respectively. Furthermore, the proposed models exhibited considerably improved performance compared to existing design code methodologies. These models can be utilized for solving similar problems in structural engineering and concrete technology with an enhanced level of accuracy

Pallet Management System: A Study of the Implementation of UID/RFID Technology for Tracking Shipping Materials within the Department of Defense Distribution Network

Sponsored Report (for Acquisition Research Program)The purpose of this MBA project is to identify the typical pallet utilization for the Defense Distribution Depot San Joaquin (DDJC) shipments to the Defense Distribution Depot San Diego (DDDC). That information will be used as the basis for suggesting a standardized reutilization management system for wood and non-wood pallets. This project will analyze the inclusion of Radio Frequency Identification and Unique Item Identification in conjunction with bar code technology for the improvement of asset visibility within the Department of Defense''s supply network.Naval Postgraduate School Acquisition Research ProgramApproved for public release; distribution is unlimited

On excess-time correlated cumulative processes

In this paper a class of correlated cumulative processes, Bs(t) = (formula presented) Hs(Xi)Xi, is studied with excess level increments ki ≥ s, where (N(t), t ≥) is the counting process generated by the renewal sequence Tn, Tn and Xn are correlated for given n, Hs(t) is the Heaviside function and s ≥ 0 is a given constant. Several useful results, for the distributions of Bs(t), and that of the number of excess (non-excess) increments on (0, t) and the corresponding means, are derived. First passage time problems are also discussed and various asymptotic properties of the processes are obtained. Transform results, by applying a flexible form for the joint distribution of correlated pairs (Tn, Xn) are derived and inverted. The case of non-excess level increments, Xi< s, is also considered. Finally, applications to known stochastic shock and pro-rata warranty models are given. © 1995 Operational Research Society Ltd

Reliability analysis and optimization applications of a two-unit standby redundant system with spare units

Consider a two-unit standby redundant system with two main units, one repair facility, and n spare units. When the main unit has failed and the other is under repair, a spare unit takes over the operation and if it fails, it is replaced by a new one until the repair of the failed unit is completed. The system fails when the last spare unit fails while one main unit is under repair and the other has failed. In this paper, we derive expressions for 1) the distribution function of the first time to system failure, 2) the probability that the total number of failed spare units during the time interval (0,t] is n and 3) the mean of the total number of failed spare units in (0,t] and its asymptotic behaviour. Introducing costs incurred for each failed main unit and each failed spare unit, the expected cost per unit of time of the system was also derived. Finally an optinmization problem is discussed in order to compare the expected cost of the system with both main units and spare units with that of spare units only, and particular cases are considered. © 1994