Accelerating Convergence of Leapfrogging Optimization - Applications to Nonlinear Process Modeling and Nonlinear Model Predictive Control

Conventionally used optimization methods in chemical engineering applications such as linear programming (LP), Levenberg-Marquardt and sequential quadratic programming (SQP) handle nonlinear objective function (OF) surfaces by linearizing or assuming quadratic behavior of the surfaces [1]. Process modeling and nonlinear model predictive control (NMPC) applications, however, present OF surfaces with surface aberrations such as steep slopes, discontinuities, and hard constraints which require a robust and efficient optimization method. Therefore, an optimization method that can handle surface aberrations is required.Leapfrogging (LF) is a recently developed direct search optimization method, potentially best-in-class, which can handle surface aberrations. LF starts with a set of players (trial solutions), randomly placed in the decision variable (DV) space. The worst player (player with the worst OF value) leaps over the best player into a reflected hypervolume [2]. The leapovers continue until all the players converge. LF is robust and efficient - with minimal computation effort (compared to conventional optimization methods), it can handle the challenges posed by nonlinear OF surfaces. LF was demonstrated on over 40 test functions and several modeling and NMPC applications. Rigorous fundamental analysis of LF is required - for a finer understanding of the method, exploring opportunities for improvement and scaling LF applications to large scale systems.This work is focused on exploring and analyzing methods to accelerate convergence of LF, demonstrating application credibility on nonlinear process modeling of steady state binary distillation and NMPC of a binary distillation column. Accelerating convergence opens the doors for using LF in large scale problems that have several hundred variables such as real time optimization and refinery planning where computational effort and time are of essence. Distillation modeling is constrained, nonlinear, and has optimum confined to a narrow region; distillation control is multivariable, interacting, nonlinear and has severe disturbances.Completion of this work will provide new fundamental understanding of LF which is critical for creating opportunities for algorithm improvement. Demonstrating application to nonlinear process modeling and NMPC will create application credibility, reveal practicality and serve as proof of concept that LF can be an optimizer of choice for use in the process control community.Chemical Engineerin

Optimization of Processes for Sustainability

This research is focused on developing a methodology to optimize processes for sustainability. To design a sustainable process that addresses economic, environmental and social concerns is a complex multiobjective problem. Current state of research is restricted to optimizing processes for profit while satisfying environmental regulations and/or measuring the sustainability of the process using already developed tools. There is no methodology that optimizes a process for being sustainable. There is an increasing need to fill the gap between solving a complicated multiobjective problem for sustainability concerns and a simple single objective problem of profit. This research therefore converts the multiobjective problem of designing processes for being sustainable into a single objective problem by using a method of constraints and a method of weights to combine the objective functions. The methodology combines information from an OSU developed SUSTAINABILITY EVALUATOR and uses a commercially available sequential modular simulator Aspen Plus to optimize processes.School of Chemical Engineerin

Association analysis of nine candidate gene polymorphisms in Indian patients with type 2 diabetic retinopathy

<p>Abstract</p> <p>Background</p> <p>Diabetic retinopathy (DR) is classically defined as a microvasculopathy that primarily affects the small blood vessels of the inner retina as a complication of diabetes mellitus (DM).It is a multifactorial disease with a strong genetic component. The aim of this study is to investigate the association of a set of nine candidate genes with the development of diabetic retinopathy in a South Indian cohort who have type 2 diabetes mellitus (T2DM).</p> <p>Methods</p> <p>Seven candidate genes (<it>RAGE, PEDF, AKR1B1, EPO, HTRA1, ICAM </it>and <it>HFE</it>) were chosen based on reported association with DR in the literature. Two more, <it>CFH </it>and ARMS2, were chosen based on their roles in biological pathways previously implicated in DR. Fourteen single nucleotide polymorphisms (SNPs) and one dinucleotide repeat polymorphism, previously reported to show association with DR or other related diseases, were genotyped in 345 DR and 356 diabetic patients without retinopathy (DNR). The genes which showed positive association in this screening set were tested further in additional sets of 100 DR and 90 DNR additional patients from the Aravind Eye Hospital. Those which showed association in the secondary screen were subjected to a combined analysis with the 100 DR and 100 DNR subjects previously recruited and genotyped through the Sankara Nethralaya Hospital, India. Genotypes were evaluated using a combination of direct sequencing, TaqMan SNP genotyping, RFLP analysis, and SNaPshot PCR assays. Chi-square and Fisher exact tests were used to analyze the genotype and allele frequencies.</p> <p>Results</p> <p>Among the nine loci (15 polymorphisms) screened, SNP rs2070600 (G82S) in the <it>RAGE </it>gene, showed significant association with DR (allelic P = 0.016, dominant model P = 0.012), compared to DNR. SNP rs2070600 further showed significant association with DR in the confirmation cohort (P = 0.035, dominant model P = 0.032). Combining the two cohorts gave an allelic P < 0.003 and dominant P = 0.0013). Combined analysis with the Sankara Nethralaya cohort gave an allelic P = 0.0003 and dominant P = 0.00011 with an OR = 0.49 (0.34 - 0.70) for the minor allele. In <it>HTRA1</it>, rs11200638 (G>A), showed marginal significance with DR (P = 0.055) while rs10490924 in LOC387715 gave a P = 0.07. No statistical significance was observed for SNPs in the other 7 genes studied.</p> <p>Conclusions</p> <p>This study confirms significant association of one polymorphism only (rs2070600 in <it>RAGE</it>) with DR in an Indian population which had T2DM.</p

Local Context and Global Strategy: Extending the Integration Responsiveness Framework to Subsidiary Strategy

The integration-responsiveness (IR) framework is a leading analytical tool of global strategy but it is less valuable in explaining the heterogeneity of strategic choice for subsidiaries within an MNE. We propose an IRE framework of subsidiary strategy that complements the IR framework for the subsidiary level with a third dimension—selling to local versus export markets (E). Resource-based considerations suggest that subsidiary strategies must fit the resources both the parent MNE and the local context. We examine how our three dimensions of subsidiary strategy are locally contingent. We suggest that local resource endowments, local competition, and the distance between the home and host country influence the use of responsiveness and exporting strategies, but influence integration strategies only to a small degree. We find empirical support for hypotheses developed from these arguments using survey data from MNE subsidiaries in two Central and Eastern European economies

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Special Issue on Cluster and Network-Based Computing

The emerging trend in high-performance computing is moving toward cluster and network-based computing, an approach in which powerful commodity singlemultiprocessor workstations or PCs are connected by either a general pur- pose local area network or specialized interconnects to achieve high performance. Such systems built with off-the-shelf components not only make them easy to build, but also decrease the lead time to market. These systems can be easily upgraded with constantly improving workstation PC and network hardware, unlike the traditional parallel machines built with custom components. The recent advances in high-speed networks, efficient networking protocols, and improved microprocessor design for higher performance, coupled with the availability of public domain software, including operating system, compiler tools, and message passing libraries, make cluster computing appealing in terms of both performance and cost-effectiveness. The increasing popularity of the Linux operating system and the availability of low cost PCs have resulted in a large number of Beowulf clusters. There have also been similar efforts on PC clusters based on the Windows NT operating system. The cost-performance benefit offered by PC clusters has put them in the list of top 500 supercomputers. Along with this, web-based computing or internet-based computing is becoming a popular paradigm for cost-effective high-performance computing

Leiomyosarcoma of the inferior vena cava: An uncommon cause of inferior vena caval obstruction

Venous leiomyosarcomas are rare neoplasms usually afflicting the inferior vena cava. They usually present with abdominal pain, and an abdominal mass with features of IVC obstruction. Early and accurate diagnosis is essential, because radical surgery offers the only hope of prolonged survival. Imaging combined with guided biopsies forms the mainstay of reliable presurgical diagnosis. We describe a 48-year-old woman with leiomyosarcoma of the hepatic segment of the IVC, who presented with features of IVC obstruction. The imaging features of the tumor are described with a review of the current literature