V.K. Jayaraman

Feature extraction and denoising using kernel PCA

Kernel PCA methodology, an elegant nonlinear generalization of the linear PCA, is illustrated by considering the examples of (i) denoising chaotic time series and, (ii) prediction of properties of polymer nanocomposites developed in our laboratory. Kernel PCA captures the dominant nonlinear features of the original data by transforming it to a high dimensional feature space. An appropriately defined kernel function allows the computations to be performed in the original input space and facilitates extraction of substantially higher number of principal components enabling excellent denoising and feature extraction capabilities. Use of simple matrix algebra in simulations makes the method an attractive alternative to some hard optimization based methodologies.

Solution of constrained optimization problems by multi-objective genetic algorithm

This paper introduces a method for constrained optimization using a modified multi-objective algorithm. The algorithm treats the constraints as objective functions and handles them using the concept of Pareto dominance. The population members are ranked by two different ways: first ranking is based on objective function value and the second ranking is based on Pareto dominance of the population members. The maintenance of elite lists for both rankings facilitates preservation of potentially superior solutions. A range of problems including non-linear programming and mixed integer non-linear programming has been solved to test the efficacy of the proposed algorithm. The algorithm effectively handles constraints encountered in both small-scale and large-scale optimization problems. The performance of the algorithm compares favourably with existing evolutionary and heuristic approaches.

Nadi Tarangini: A Pulse Based Diagnostic System

Ayurveda is a traditional medicine and natural healing system in India. Nadi-Nidan (pulse-based diagnosis) is a prominent method in Ayurveda, and is known to dictate all the salient features of a human body. In this paper, we provide details of our procedure for obtaining the complete spectrum of the nadi pulses as a time series. The system Nadi Tarangini contains a diaphragm element equipped with strain gauge, a transmitter cum amplifier, and a digitizer for quantifying analog signal. The system acquires the data with 16-bit accuracy with practically no external electronic or interfering noise. Prior systems for obtaining the nadi pulses have been few and far between, when compared to systems such as ECG. The waveforms obtained with our system have been compared with these other similar equipment developed earlier, and is shown to contain more details. The pulse waveform is also shown to have the desirable variations with respect to age of patients, and the pressure applied at the sensing element. The system is being evaluated by Ayurvedic practitioners as a computer-aided diagnostic tool.

Dynamic Optimization of Fed-Batch Bioreactors Using the Ant Algorithm

The ant colony algorithm, mimicking the cooperative search behavior of ants in real life, has been employed for the dynamic optimization of fed‐batch bioreactors. To test the capability of this new heuristic algorithm, two well‐known and extensively studied systems have been chosen. The algorithm rapidly converges to optimal feed rate profiles, which maximize the overall production of the desired product and the profits in a computationally efficient and robust manner. The optimal profiles evolved are easy to implement in plant operation. The algorithm compares favorably with the other known techniques.

Arterial Pulse System: Modern Methods For Traditional Indian Medicine

Ayurveda is one of the most comprehensive healing systems in the world and has classified the body system according to the theory of Tridosha to overcome ailments. Diagnosis similar to the traditional pulse-based method requires a system of clean input signals, and extensive experiments for obtaining classification features. In this paper we briefly describe our system of generating pulse waveforms and use various feature detecting methods to show that an arterial pulse contains typical physiological properties. The beat-to-beat variability is captured using a complex B-spline mother wavelet based peak detection algorithm. We also capture - to our knowledge for the first time - the self- similarity in the physiological signal, and quantifiable chaotic behavior using recurrence plot structures.

Clinical Application and Outcomes of Over the Scope Clip Device: Initial US Experience in Humans

Background. OTSCs are now available in the US for various indications. Methods. Retrospective review of OTSCs used from January 2011 to April 2012. Results. Twenty-four patients underwent placement of 28 OTSCs. Indications included postsurgical fistula, perforations, anastomotic leak, prophylactic closure after EMR, postpolypectomy bleeding, tracheoesophageal fistula, and jejunostomy site leak. Instruments used to grasp the tissue were dedicated (bidirectional forceps or tripronged device) and nondedicated devices (rat/alligator forceps or suction). Success was higher with nondedicated devices (12.5% versus 86.5%, P = 0.0004). Overall, OTSC was effective in 15/27 procedures. Defect closure was complete in 12/21. Mean followup was 2.9 months (1–8u2009m). Mean defect size was 10u2009mm (5–25u2009mm). A trend towards higher success was noted in defects <10u2009mm compared to defects >10u2009mm (90% versus 60%; P = 0.36). No difference was noted in closure of fresh (<72u2009hrs) versus chronic defects (>1 month) (75% versus 67%). There were no complications. Conclusion. The OTSC provides a safe alternative to manage fistula, perforation, and bleeding. No significant difference was seen for closure of early fistula or perforations as compared to chronic fistula. Rat-tooth forceps or suction was superior to the dedicated devices.

Optimization of media by evolutionary algorithms for production of polyols

Biotransformation of sucrose-based medium to polyols has been reported for the first time using osmophilic yeast, Hansenula anomala. A new, real coded evolutionary algorithm was developed for optimization of fermentation medium in parallel shake-flask experiments. By iteratively employing the nature-inspired techniques of selection, crossover, and mutation for a fixed number of generations, the algorithm obtains the optimal values of important process variables, namely, inoculum size and sugar, yeast extract, urea, and MgSO4 concentrations. Maximum polyols yield of 76.43% has been achieved. The method is useful for reducing the overall development time to obtain an efficient fermentation process.

Multiobjective Optimization of Reactor–Regenerator System Using Ant Algorithm

Abstract This article focuses on the development of a multiobjective optimization algorithm for a tubular reactor–regenerator system with a moving deactivating catalyst. The task is to find the optimal temperature profile along the tubular reactor, catalyst recycle ratio, and the regeneration capacity for maximizing the process profit flux, selectivity, and conversion. A new heuristic technique, viz, ant colony optimization method has been employed to obtain the Pareto optimal set of solutions.

A Comparative Study of Annealing Methods for Batch Scheduling Problems

Batch Scheduling is an important problem, relevant to a large sector of the processing industries. Methods like Simulated Annealing have been traditionally used in dealing with scheduling problems that are combinatorially complex. In this paper the performance of four different annealing strategies, Simulated Annealing (SA), Threshold Acceptance (TA) and Multicanonical Jump Walk Annealing (MJWA) with and without window factor scheduling have been compared for small and large size problems. Criteria such as robustness of the method and mean deviation from the optimal solution reveal that the MJWA with window factor scheduling is far superior to SA, TA or MJWA without window factor scheduling.

Successful Gastric Volvulus Reduction and Gastropexy Using a Dual Endoscope Technique

Gastric volvulus is a life threatening condition characterized by an abnormal rotation of the stomach around an axis. Although the first line treatment of this disorder is surgical, we report here a case of gastric volvulus that was endoscopically managed using a novel strategy. An 83-year-old female with a history of pancreatic cancer status postpylorus-preserving Whipple procedure presented with a cecal volvulus requiring right hemicolectomy. Postoperative imaging included a CT scan and upper GI series that showed a gastric volvulus with the antrum located above the diaphragm. An upper endoscopy was advanced through the pylorus into the duodenum and left in this position to keep the stomach under the diaphragm. A second pediatric endoscope was advanced alongside and used to complete percutaneous endoscopic gastrostomy (PEG) placement for anterior gastropexy. The patients volvulus resolved and there were no complications. From our review of the literature, the dual endoscopic technique employed here has not been previously described. Patients who are poor surgical candidates or those who do not require emergent surgery can possibly benefit the most from similar minimally invasive endoscopic procedures as described here.