149 research outputs found
GPU-accelerated depth map generation for X-ray simulations of complex CAD geometries
Get PDFInteractive 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
Get PDFFiber-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
Get PDFHow 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
Get PDFDelivering 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
Get PDFIn 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
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
Palladium Metal Membranes for Hydrogen purification with Titanium as an Intermediate layer
No full textPalladium (Pd) metal membranes are used for the production and effective storage of high purity hydrogen. To overcome the crack and de-lamination of Pd membranes at room temperature during several hydrogen loading and de-loading cycles, a Titanium (Ti) of very small thickness of less than 10 nm is introduced as an intermediate layer between the palladium film and an oxidized Si wafer substrate. The objective of the project is to study the thin film growth of Ti and Pd films deposited for different titanium thickness at different argon sputtering pressures over oxidized Si wafer substrate. The surface roughness analysis of titanium and palladium films with its corresponding AFM images is done by Gwyddion software which shows the initial deposition and growth of films for corresponding film thicknesses. Introducing titanium reduces the surface roughness of palladium and enhances the hydrogen flux through palladium films. Texture and stress measurements of the films from XRD also accounts for the growth of the films on the substrate. The hydrogen loading and de-loading process carried out for Pd and Ti films resulted in an elimination of the crack and de-lamination of the palladium film from the substrate with titanium acting as a good adhesion layer.Mechanical, Maritime and Materials EngineeringMaterials Science and Engineerin
Effect of diallyl disulphide on hepatic glucose regulating enzymes in diabetic rats
Get PDF567-571This study examines whether the glucose regulating enzymes mediate hypoglycaemic effect of diallyl disulphide (DADS) since the biochemical mechanisms by which the latter regulates hepatic glucose-metabolizing enzymes remain unknown. Hepatic hexokinase, glucose-6-P-D and pyruvate kinase are the important glucose metabolising enzymes that control blood glucose homeostasis and considered to be potential targets for antidiabetic drugs. DADS is an important phytoconstituent of garlic (Allium sativum Linn.) which has been reported to possess hypoglycaemic effect. Diabetes was induced in rats by alloxan and the diabetic rats were given DADS for 30 days and the effect was compared with the standard hypoglycaemic drug metformin. The levels of blood glucose and insulin were measured using spectrophotometer and by ELISA method respectively. Activities of hepatic hexokinase, glucose-6-PD, and pyruvate kinase enzymes in hepatic tissues were measured in DADS and metformin treated diabetic rats. DADS significantly reduced the level of blood glucose and simultaneously augmented those of insulin, pyruvate kinase, hexokinase and glucose-6-PD enzyme activities almost similar to metformin. The hypoglycaemic effect of this compound may be explained, in part, by its inhibition of these enzyme activities and improved hepatic glucose utilization. This observation offers scope for new therapeutic approach in treating diabetes particularly in insulin- resistant cases
THB‑Diff: a GPU‑accelerated diferentiable programming framework for THB‑splines
Get PDFWe have developed a differentiable programming framework for truncated hierarchical B-splines (THB-splines), which can be used for several applications in geometry modeling, such as surface fitting and deformable image registration, and can be easily integrated with geometric deep learning frameworks. Differentiable programming is a novel paradigm that enables an algorithm to be differentiated via automatic differentiation, i.e., using automatic differentiation to compute the derivatives of its outputs with respect to its inputs or parameters. Differentiable programming has been used extensively in machine learning for obtaining gradients required in optimization algorithms such as stochastic gradient descent (SGD). While incorporating differentiable programming with traditional functions is straightforward, it is challenging when the functions are complex, such as splines. In this work, we extend the differentiable programming paradigm to THB-splines. THB-splines offer an efficient approach for complex surface fitting by utilizing a hierarchical tensor structure of B-splines, enabling local adaptive refinement. However, this approach brings challenges, such as a larger computational overhead and the non-trivial implementation of automatic differentiation and parallel evaluation algorithms. We use custom kernel functions for GPU acceleration in forward and backward evaluation that are necessary for differentiable programming of THB-splines. Our approach not only improves computational efficiency but also significantly enhances the speed of surface evaluation compared to previous methods. Our differentiable THB-splines framework facilitates faster and more accurate surface modeling with local refinement, with several applications in CAD and isogeometric analysis.This article is published as Moola, Ajith, Aditya Balu, Adarsh Krishnamurthy, and Aishwarya Pawar. "THB-Diff: a GPU-accelerated differentiable programming framework for THB-splines." Engineering with Computers (2023): 1-17. doi: https://doi.org/10.1007/s00366-023-01929-1. © The Author(s) 2023. This open access article is licensed under a Creative Commons Attribution 4.0. (http://creativecommons.org/licenses/by/4.0/
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