179 research outputs found
GPU-accelerated depth map generation for X-ray simulations of complex CAD geometries
No full textInteractive x-ray simulations of complex computer-aided design (CAD) models can provide valuable insights for better interpretation of the defect signatures such as porosity from x-ray CT images. Generating the depth map along a particular direction for the given CAD geometry is the most compute-intensive step in x-ray simulations. We have developed a GPU-accelerated method for real-time generation of depth maps of complex CAD geometries. We preprocess complex components designed using commercial CAD systems using a custom CAD module and convert them into a fine user-defined surface tessellation. Our CAD module can be used by different simulators as well as handle complex geometries, including those that arise from complex castings and composite structures. We then make use of a parallel algorithm that runs on a graphics processing unit (GPU) to convert the finely-tessellated CAD model to a voxelized representation. The voxelized representation can enable heterogeneous modeling of the volume enclosed by the CAD model by assigning heterogeneous material properties in specific regions. The depth maps are generated from this voxelized representation with the help of a GPU-accelerated ray-casting algorithm. The GPU-accelerated ray-casting method enables interactive (> 60 frames-per-second) generation of the depth maps of complex CAD geometries. This enables arbitrarily rotation and slicing of the CAD model, leading to better interpretation of the x-ray images by the user. In addition, the depth maps can be used to aid directly in CT reconstruction algorithms.This proceeding may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This proceeding appeared in Grandin, Robert J., Gavin Young, Stephen D. Holland, and Adarsh Krishnamurthy. "GPU-accelerated depth map generation for X-ray simulations of complex CAD geometries." In AIP Conference Proceedings, vol. 1949, no. 1, p. 190002. AIP Publishing LLC, 2018, and may be found at
DOI: 10.1063/1.5031636.
Copyright 2018 Author(s).
Posted with permission
Incorporation of composite defects from ultrasonic NDE into CAD and FE models
No full textFiber-reinforced composites are widely used in aerospace industry due to their combined properties of high strength and low weight. However, owing to their complex structure, it is difficult to assess the impact of manufacturing defects and service damage on their residual life. While, ultrasonic testing (UT) is the preferred NDE method to identify the presence of defects in composites, there are no reasonable ways to model the damage and evaluate the structural integrity of composites. We have developed an automated framework to incorporate flaws and known composite damage automatically into a finite element analysis (FEA) model of composites, ultimately aiding in accessing the residual life of composites and make informed decisions regarding repairs. The framework can be used to generate a layer-by-layer 3D structural CAD model of the composite laminates replicating their manufacturing process. Outlines of structural defects, such as delaminations, are automatically detected from UT of the laminate and are incorporated into the CAD model between the appropriate layers. In addition, the framework allows for direct structural analysis of the resulting 3D CAD models with defects by automatically applying the appropriate boundary conditions. In this paper, we show a working proof-of-concept for the composite model builder with capabilities of incorporating delaminations between laminate layers and automatically preparing the CAD model for structural analysis using a FEA software.This proceeding may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This proceeding appeared in Bingol, Onur Rauf, Bryan Schiefelbein, Robert J. Grandin, Stephen D. Holland, and Adarsh Krishnamurthy. "Incorporation of composite defects from ultrasonic NDE into CAD and FE models." AIP Conference Proceedings 1806, no. 1, (2017): 150004. , and may be found at DOI: 10.1063/1.4974728. Posted with permission.</p
Optogenetic control of developmental signaling pathways
No full textHow a complex multicellular organism forms from a single cell is a question that defies simplistic understanding. Yet, embryonic developmental programs use a surprisingly small set of signaling pathways to pattern the embryonic tissue into germ layers from which the various tissues and organs emerge. A hallmark of embryonic development is that these recurring developmental signaling pathways are carefully orchestrated in space and time to facilitate proper development. Understanding the spatiotemporal intricacies of these pathways necessitates tools which enable their perturbation in precisely defined spatiotemporal patterns. Optogenetics uses light-induced conformational changes to enable or disable protein-protein interactions, thereby permitting control of signal transduction at the flip of a switch. Consequently, light is emerging as a powerful tool to study embryonic development owing to its rapid, reversible and residue-free application, which empowers the researcher with excellent spatial and temporal control of signaling. Here, I first review recent accomplishments in optical microscopy and optogenetics which highlight the dual roles of light in visualizing as well as perturbing cellular microenvironments and processes. Second, I present an optogenetic approach to control the mitogen-activated protein kinase (MAPK) pathway which we successfully applied in both neuroblasts and frog embryos. Third, I demonstrate an optogenetic approach to control the Wnt signaling pathway in mammalian cells and frog embryos. Finally, I propose and provide working proof for a generalizable optogenetic platform to control those developmental signaling pathways, the activities of which involve the homo-association of plasma membrane-localized receptor tyrosine kinases.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2021-12-01The student, Vishnu Vardhan Krishnamurthy, accepted the attached license on 2019-11-27 at 10:27.The student, Vishnu Vardhan Krishnamurthy, submitted this Dissertation for approval on 2019-11-27 at 10:29.This Dissertation was approved for publication on 2019-12-04 at 10:19.DSpace SAF Submission Ingestion Package generated from Vireo submission #14554 on 2020-02-28 at 17:36:14Made available in DSpace on 2020-03-02T22:38:43Z (GMT). No. of bitstreams: 3
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Prospective: A Data-Driven Technique to Predict Web Service Response Time Percentiles
No full textDelivering fast response times for user transactions is a critical requirement for Web services. Often, a Web service has Service Level Agreements (SLA) with its users that quantify how quickly the service has to respond to a user transaction. Typically, SLAs stipulate requirements for Web service response time percentiles, e.g., a specified target for the 95th percentile of response time. Violating SLAs can have adverse consequences for a Web service operator. Consequently, operators require systematic techniques to predict Web service response time percentiles. Existing prediction techniques are very time consuming since they often involve manual construction of queuing or machine learning models. To address this problem, we propose Prospective, a data-driven approach for predicting Web service response time percentiles. Given a specification for workload expected at the Web service over a planning horizon, Prospective uses historical data to offer predictions for response time percentiles of interest. At the core of Prospective is a lightweight simulator that uses collaborative filtering to estimate response time behaviour of the service based on behaviour observed historically. Results show that Prospective significantly outperforms other baseline techniques for a wide variety of workloads. In particular, the technique provides accurate estimates even for workload scenarios not directly observed in the historical data. We also show that Prospective can provide a Web service operator with accurate estimates of the types and numbers of Web service instances needed to avoid SLA violations.Library OA Fun
Making sense of ‘new age data sets’: researching from afar
No full textThis chapter considers the central role of uncertainty for cognition and action in construction project organising with a focus on how project practitioners think about the future. It takes a cognitive approach to uncertainty in the context of a broader information processing approach to decision-making in organisations. The chapter’s main concern is the failure of this approach to connect cognition through to action. The chapter presents the UnCoCoH (Un-Certain Complex Complicated Hidden) model as a tool to assist in recognising the transition from individual cognition to collective action. It also highlights the role of narratives for stabilising uncertainty through this transition. This provides a foundation for working towards the development of a projectivity perspective in construction project organising and advancing a research agenda for this program of research.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Integral Design & Managemen
Cattle and carnivore coexistence in Alberta: The role of compensation programs
No full textIn Alberta, Canada beef producers share the landscape with large carnivores where interactions can lead to negative outcomes. We had 672 Alberta beef producers complete an online survey in spring 2014 to access the occurrence and outcomes of cattle-carnivore interactions.•We found that a majority (64%) reported losses from carnivore depredation. The average rate of calf depredation was reported at 2%, but the rate was highly variable between producers (ranging from 0 to 25% calf loss annually). The direct annual economic loss to depredation for survey respondents was 22 million.• Alberta's Wildlife Predator Compensation Program (WPCP) paid out an average of $220,584 annually from 2011-2013. The WPCP was under-utilized,64% of producers did not report to the program,and did not adequately address financial burden experienced by producers from 2011 2013.•Producers identified a series of challenges with the WPCP including the excessive burden of proof and the effort to value ratio being too low.•We provide recommendations to improve the WPCP based on a literature review and our survey findings
Performance of a 1 kW Class Nafion-PTFE Composite Membrane Fuel Cell Stack
No full textComposite membranes have been prepared by impregnation of Nafion into the expanded polytetrafluoroethylene (EPTFE) matrix. Nafion loading in the composite membranes was kept constant at 2 mg/cm2. The lower amount of electrolyte per unit area in the composite membranes offers cost advantages compared to conventional membrane of 50 μm thickness with an electrolyte loading of ~9 mg/cm2. Composite membranes (30 μm thickness) were found to have higher thermal stability and mechanical strength compared to the conventional membranes (50 μm thickness). The performance of the membrane electrode assembly made with these composite membranes was comparable to that of the conventional membranes. Single cells fabricated from these MEAs were tested for their performance and durability before scaling them up for large area. The performance of a 20-cell stack of active area 330 cm2 fabricated using these membranes is reported
Antagonistic Efficiency of Aspergillus giganteus as a Biocontrol Agent against Aflatoxigenic Aspergillus flavus Infecting Maize
No full textAspergillus flavus is a fungal pathogen which infects maize crops and produces aflatoxin thus bringing
about huge losses in crop production. Developing biocontrol agents against Aspergillus flavus has been
the best strategy for the control of contamination in the fields. The aim of this study was to evaluate
the biocontrol potential of Aspergillus giganteus against A. flavus by in vitro coculture studies. The
effect of antagonism was studied by varying the carbon and nitrogen sources and under different
interacting conditions of pH, temperature and water activities. The conidia production by A. flavus
during coculture conditions favourable for antagonism was also assessed. A significantly notable growth
inhibition of about 86.1% was brought about by A. giganteus in the coculture, which surrounded the
mycelia of pathogenic A. flavus, arresting its growth. A maximum inhibition of 86.1% was observed
when sucrose was used as the carbon source and a significantly higher inhibition of 90.93% was seen
when beef extract was used as the nitrogen source. Among the different temperatures tested, the
highest inhibition was observed at 30°C which was 87.43%. An increasing trend in the inhibitions were
seen with decrease in pH and water activity (aw), where, the highest inhibition was 89.75% for pH 6.0
and 94.03% for aw 0.846. Drastic reductions in conidial number and halting of sclerotia production was
observed in coculture clearly suggesting that A. giganteus will serve to be a potent and promising
biocontrol strain under different environmental conditions
Evaluation of Isosorbide Mononitrate for Preinduction of Cervical Ripening: A Randomized Placebo-Controlled Trial.
No full textObjective:To evaluate the safety and efficacy of Isosorbide mononitrate (IMN) as a cervical ripening agent prior to induction of labour in term pregnant women.
Materials and methods: A randomized placebo-controlled study was conducted on 100 term singleton pregnancies planned for induction of labour. The participants were randomly assigned to two groups. One group received 40 mg IMN and the other group received 40mg of placebo kept vaginally. The main outcome of this study was to evaluate the efficacy of IMN in cervical ripening based on the change in modified Bishop score and the effect on time duration between the drug insertion and delivery. Safety of isosorbide mononitrate was assessed by measuring variables related to maternal and neonatal outcomes.
Results:Baseline demographic characteristics were similar in both groups. The mean change in modified Bishop score after 2 doses of 40mg IMN was insignificant when compared to placebo. Though IMN shortened the time duration between the drug insertion to delivery when compared to placebo, it was statistically insignificant. The need for oxytocin and 2(nd) ripening agent was less in IMN group when compared to placebo group but statistically this also proved to be insignificant. It was noted that there was an increase in caesarean deliveries in IMN than in placebo group. IMN did not cause any significant change in maternal hemodynamics and adverse side effects. Though NICU admission and stay was less in IMN than in placebo group, it was statistically insignificant.
Conclusion:Though IMN did not cause any maternal and neonatal adverse effects, it was found to be inefficient in comparison to placebo as a cervical ripening agent
Barriers to Digital Transformation: A case study of a chemical B2B company
No full textDigital transformation is taking place all around and there is hardly anything has not been affected (Reddy & Reinartz, 2017). It is reshaping a wide range of activities, influences the way we work, our communication and our consumer behaviors (Piccinini, Hanelt, R.W., & L.M., 2015). Benefits are less visible in certain situations, but a lot of administrative processes can be automated or digitized and manual labour can be reduced (Salo, 2006). In a business context, digital tools are widely adopted as ERP, CRM and e-business solutions, however some, like e-business exhibit a significant gap between adoption and widespread adoption use (Zhu, Dong, Xu, & Kraem, 2006). Various theories predict the adoption of technologies such as innovation diffusion, TAM and TOE Framework, but there is a gap in digital transformation literature that depicts the barriers to digital transformation, particularly taking into consideration its nature as a discontinuous change process that holistically transforms its people, organization, structure, in the pursuit of value creation (Henriette, Feki, & Boughzala, 2016). Furthermore, the chemical B2B industry has garnered a reputation for being a latecomer industry (Koehn, 2018). New startups have begun to enter the market where they leverage platform e-commerce services to lower prices and retain cost advantages, where large incumbent companies hesitate to try digital channels.Management of Technology (MoT
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