@article{kripakaran_gupta_matzen_2008, title={Computational framework for remotely operable laboratories}, volume={24}, ISSN={["0177-0667"]}, DOI={10.1007/s00366-008-0089-y}, abstractNote={Decision-makers envision a significant role for remotely operable laboratories in advancing research in structural engineering, as seen from the tremendous support for the network for earthquake engineering simulation (NEES) framework. This paper proposes a computational framework that uses LabVIEW and web technologies to enable observation and control of laboratory experiments via the internet. The framework, which is illustrated for a shaketable experiment, consists of two key hardware components: (1) a local network that has an NI-PXI with hardware for measurement acquisition and shaketable control along with a Windows-based PC that acquires images from a high-speed camera for video, and (2) a proxy server that controls access to the local network. The software for shaketable control and data/video acquisition are developed in the form of virtual instruments (VI) using LabVIEW development system. The proxy server employs a user-based authentication protocol to provide security to the experiment. The user can run perl-based CGI scripts on the proxy server for scheduling to control or observe the experiment in a future timeslot as well as gain access to control or observe the experiment during that timeslot. The proxy server implements single-controller multiple-observer architecture so that many users can simultaneously observe and download measurements as a single controller decides the waveform input into the shaketable. A provision is also created for users to simultaneously view the real-time video of the experiment. Two different methods to communicate the video are studied. It is concluded that a JPEG compression of the images acquired from the camera offers the best performance over a wide range of networks. The framework is accessible by a remote user with a computer that has access to a high-speed internet connection and has the LabVIEW runtime engine that is available at no cost to the user. Care is taken to ensure that the implementation of the LabVIEW applications and the perl scripts have little dependency for ease of portability to other experiments.}, number={4}, journal={ENGINEERING WITH COMPUTERS}, author={Kripakaran, Prakash and Gupta, Abhinav and Matzen, Vernon C.}, year={2008}, month={Oct}, pages={405–415} }
 @article{kripakaran_gupta_baugh_2007, title={A novel optimization approach for minimum cost design of trusses}, volume={85}, ISSN={["1879-2243"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-36049020582&partnerID=MN8TOARS}, DOI={10.1016/j.compstruc.2007.04.006}, abstractNote={This paper describes new optimization strategies that offer significant improvements in performance over existing methods for bridge-truss design. In this study, a real-world cost function that consists of costs on the weight of the truss and the number of products in the design is considered. We propose a new sizing approach that involves two algorithms applied in sequence – (1) a novel approach to generate a “good” initial solution and (2) a local search that attempts to generate the optimal solution by starting with the final solution from the previous algorithm. A clustering technique, which identifies members that are likely to have the same product type, is used with cost functions that consider a cost on the number of products. The proposed approach gives solutions that are much lower in cost compared to those generated in a comprehensive study of the same problem using genetic algorithms (GA). Also, the number of evaluations needed to arrive at the optimal solution is an order of magnitude lower than that needed in GAs. Since existing optimization techniques use cost functions like those of minimum-weight truss problems to illustrate their performance, the proposed approach is also applied to the same examples in order to compare its relative performance. The proposed approach is shown to generate solutions of not only better quality but also much more efficiently. To highlight the use of this sizing approach in a broader optimization framework, a simple geometry optimization algorithm that uses the sizing approach is presented. This algorithm is also shown to provide solutions better than the existing results in literature.}, number={23-24}, journal={COMPUTERS & STRUCTURES}, author={Kripakaran, Prakash and Gupta, Abhinav and Baugh, John W., Jr.}, year={2007}, month={Dec}, pages={1782–1794} }
 @article{gupta_kripakaran_mahinthakumar_baugh_2005, title={Genetic algorithm-based decision support for optimizing seismic response of piping systems}, volume={131}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-14544294041&partnerID=MN8TOARS}, DOI={10.1061/(asce)0733-9445(2005)131:3(389)}, abstractNote={This paper describes computational approaches used in a prototype decision support system (DSS) for seismic design and performance evaluation of piping supports. The DSS is primarily based on a genetic algorithm (GA) that uses finite element analyses, and an existing framework for high performance distributed computing on workstation clusters. A detailed discussion is presented on various issues related to the development of an efficient GA implementation for evaluating the trade-off between the number of supports and cost. An integer string representation of the type used in some existing studies, for instance, is shown to be inferior to a binary string representation, which is appropriate when supports are modeled as axially rigid. A novel seeding technique, which overcomes the inefficiencies of conventional methods in the context of pipe support optimization, is also presented. Finally, an efficient crossover scheme is proposed for generating trade-off curves and the approach is validated with respect ...}, number={3}, journal={Journal of Structural Engineering}, author={Gupta, A. and Kripakaran, P. and Mahinthakumar, G. K. and Baugh, J. W.}, year={2005}, pages={389–398} }