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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The cosolvent and association effect on polymer behaviors

Zhang, Xiangyu 08 August 2023 (has links) (PDF)
The blending or mixing is extensively utilized in diverse processes of polymers to bring about advantageous properties, but the behavior becomes intriguing when associations are involved and multi-solvents are used. Explanations based on chemistry-specific arguments are less than satisfactory in abstracting essential features, and lack the general applicability across various systems. So, this work focuses on capturing the physical force governing the phenomenon of interest by using a generic model. Highly non-trivial behaviors of polymers are often observed in multi-solvent solutions. It is known that polymers swell and dissolve in good solvents, while they tend to collapse and aggregate in poor solvents. But for some specific systems, polymers that collapse in two different poor solvents become soluble in their mixtures, corresponding to cosolvency, and conversely, polymers that swell in two different good solvents become insoluble in their mixtures, pertaining to cononsolvency. The finding suggests that cononsolvency effect relies on the interplay between polymer-cosolvent preferential adsorptions and solvent-cosolvent attractions, which are typically investigated individually. The utilization of cononsolvency effect can either modify or induce micellization, leading to significant differences in morphology and thermodynamic properties compared to conventional micelles driven solely by hydrophobic interactions. The cosolvency project reveals that it arises from the cross competitions of Van der Waals-type interactions and the associative interaction (e.g., hydrogen bonding). The molecular association has long been a classical problem in physical chemistry, as it often gives rise to ”abnormal” phenomena, such as the elevation of boiling points due to hydrogen bonding. But the understanding of its effect on polymer system still remains rudimentary. So, this work tries to answer three fundamental questions by choosing three representative systems: 1. How will supramolecular complexations change the thermodynamics equilibrium morphology; 2. What is the impact of supramolecular bonds on the free energy landscape during the transition process; 3. How will association influence the single chain coil-globule conformational transition. It is found that the association not only results in versatile morphology, but also brings about distinct transition pathways. Besides, the conformational transition shows the dependence on the association pattern, which is actually decided by the statistical nature.
2

Reshare an Operational Ontology Framework for Research Modeling, Combining and Sharing

Al Boni, Mohammad 15 August 2014 (has links)
Scientists always face difficulties dealing with disjointed information. There is a need for a standardized and robust way to represent and exchange knowledge. Ontology has been widely used for this purpose. However, since research involves semantics and operations, we need to conceptualize both of them. In this thesis, we propose ReShare to provide a solution for this problem. Maximizing utilization while preserving the semantics is one of the main challenges when the heterogeneous knowledge is combined. Therefore, operational annotations were designed to allow generic object modeling, binding and representation. Furthermore, a test bed is developed and preliminary results are presented to show the usefulness and robustness of our approach. Moreover, two aggregation techniques for fusing ontology matchers are investigated as an initial work for building an algorithm which converts descriptive ontologies into operational ones.
3

Hybrid Electric Vehicle Modeling in Generic Modeling Environment

Musunuri, Shravana Kumar 09 December 2006 (has links)
The Hybrid Electric Vehicle (HEV) is a complex electromechanical system with complex interactions among various components. Due to the large number of design variables involved, the design flexibility in the HEV makes performance studies difficult. As the system complexity and sophistication increases, it becomes much more difficult to predict these interactions and design the system accordingly. Also, different variations in the design and manufacture of various components and systems involve a large amount of work and cost to keep updated of all these variations. While the above issues ask for a flexible design environment suitable for vehicle design, most of the existing powertrain design tools are based on experiential models, such as look-up tables, which use idealized assumptions and limited experimental data. The accuracy of the results produced by these tools is not good enough for designing these new generation vehicles. Also, sometimes the designs may lead to components or systems beyond physical limitations. To make the powertrain design more efficient, the models developed must be closely related to the underlying physics of the components. Only such physics-based models can facilitate high fidelity simulations for dynamics at different time scales. This results in the quest for a design tool that manages the vehicle?s development process while maintaining tight integration between the software and physical artifacts. The thesis addresses the above issues and focuses on the modeling of HEV using model integrated computing and employing physics-based resistive companion form modeling method. For this purpose, Generic Modeling Environment (GME), software developed by Institute of Software and Integrated Systems (ISIS), Vanderbilt University is used as the platform for developing the models. A modeling environment for hybrid vehicle design is prepared and a Battery Electric Vehicle (BEV) is developed as an application of the developed environment. Resistive companion form models of various BEV components are prepared and a model interpreter is prepared for integrating the developed component models and simulating the design.
4

Metamodeling For The Hla Federation Architectures

Topcu, Okan 01 December 2007 (has links) (PDF)
This study proposes a metamodel, named Federation Architecture Metamodel (FAMM), for describing the architecture of a High Level Architecture (HLA) compliant federation. The metamodel provides a domain specific language and a formal representation for the federation adopting Domain Specific Metamodeling approach to HLA-compliant federations. The metamodel supports the definitions of transformations both as source and as target. Specifically, it supports federate base code generation from a described federate behavior, and it supports transformations from a simulation conceptual model. A salient feature of FAMM is the behavioral description of federates based on live sequence charts (LSCs). It is formulated in metaGME, the meta-metamodel for the Generic Modeling Environment (GME). This thesis discusses specifically the following points: the approach to building the metamodel, metamodel extension from Message Sequence Chart (MSC) to LSC, support for model-based code generation, and action model and domain-specific data model integration. Lastly, this thesis presents, through a series of modeling case studies, the Federation Architecture Modeling Environment (FAME), which is a domain-specific model-building environment provided by GME once FAMM is invoked as the base paradigm.
5

A Metamodel For The High Level Architecture Object Model

Cetinkaya, Deniz 01 August 2005 (has links) (PDF)
The High Level Architecture (HLA), IEEE Std. 1516-2000, provides a general framework for distributed modeling and simulation applications, called federations. HLA focuses on interconnection of interacting simulations, called federates, with special emphasis on reusability and interoperability. An HLA object model, be it a simulation object model (SOM), a federation object model (FOM) or the management object model (MOM), describes the data exchanged during federation execution. This thesis introduces a metamodel for the HLA Object Model, fully accounting for IEEE Std. 1516.2. The metamodel is constructed with GME (Generic Modeling Environment), a meta-programmable tool for domain-specific modeling, developed at Vanderbilt University. GME generates a design environment for HLA object models having the HLA OM metamodel as input. This work can be regarded as a step for bringing model-integrated computing to bear on HLA-based distributed simulation.
6

Modélisation numérique discrète du comportement mécanique sous impact des structures d'écrans de filets pare-pierres / Discrete numerical modeling of the mechanical behavior of rockfall barriers under impact

Coulibaly, Jibril 16 November 2017 (has links)
Cette thèse présente un modèle générique d'écrans de filets pare-blocs sous sollicitations dynamiques de type impacts. Ces ouvrages pare-blocs sont décrits comme un assemblage abstrait de leurs principaux constituants. Le modèle développé permet ainsi de représenter la plupart des technologies existantes. Un code de calcul en C++ utilisant une Méthode aux Éléments Discrets est développé afin de réaliser les simulations numériques d'impacts. La description générique des ouvrages est mise en œuvre au niveau du code de calcul grâce à une structuration des données et une programmation orientée objet correspondantes. Le modèle générique est complété par deux modèles mécaniques de constituants. Dans un premier temps, un modèle mécanique de filet à anneaux à 4 contacts est développé. Ce modèle est calibré et validé par une campagne expérimentale réalisée sur des anneaux en acier utilisés dans les écrans de filets. Dans un second temps, un modèle général de câble glissant est développé pour modéliser le phénomène d'effet rideau. Ce modèle démontre de fortes capacités de description des phénomènes de glissement et de très bonnes performances de calcul. Enfin, des essais d'impact en vraie grandeur sur deux écrans de filets de technologies différentes sont utilisés afin de valider le modèle générique. Les simulations numériques de ces essais sur ouvrages réels mettent en évidence la pertinence du modèle développé. Les résultats numériques sont en très bon accord avec les expérimentations et le modèle présente des capacités prédictives pertinentes dans la perspective d'usage en ingénierie. Les déformations, les temps de chargement et l'intensité des efforts sont obtenus avec des erreurs inférieures à 10 %. Des simulations complexes d'impacts répétés sont réalisées pour la première fois et le comportement lors de l'impact et pendant la phase de retour élastique après impact est bien appréhendé par le modèle. / This thesis introduces a generic model of rockfall barriers under impact loading. The structures are described as an abstract assembly of their main components. The developed model thereby enables the consideration of most of the existing technologies. A C++ code based on the Discrete Element Method is developed in order to perform the numerical simulations of impacts. The generic description of the barriers is implemented at the code level using a corresponding data structure and object-oriented programming. The generic model is completed by the mechanical models of two components. First, a mechanical model of 4-contact interlaced ring nets is developed. An experimental campaign is carried out to calibrate and validate the model against steel wire rings used in rockfall restraining nets. Second, a general sliding cable model is developed to account for the curtain effect. This model demonstrates great capabilities in describing sliding phenomena and a low computational cost. Finally, full-scale impact tests performed on two barriers of different technologies are used to validate the generic model. Numerical simulations of the full-scale tests highlight the relevance of the developed model. Numerical results agree finely with experiments and the model exhibits compelling predictive capacities for engineering applications. Deformations, loading time and forces magnitude are all predicted within 10 % relative error. Complex and unprecedented simulations of repeated impacts are carried out and the model is able to reproduce the barrier behavior both during the impact phase and after springback.
7

Integrating recommender systems into domain specific modeling tools

Nair, Arvind 09 March 2017 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / This thesis investigates integrating recommender systems into model-driven engineering tools powered by domain-specific modeling languages. The objective of integrating recommender systems into such tools is overcome a shortcoming of proactive modeling where the modeler must inform the model intelligence engine how to progress when it cannot automatically determine the next modeling action to execute (e.g., add, delete, or edit). To evaluate our objective, we integrated a recommender system into the Proactive Modeling Engine, which is a add-on for the Generic Modeling Environment (GME). We then conducted experiments to both subjective and objectively evaluate the enhancements to the Proactive Modeling Engine. The results of our experiments show that integrating recommender system into the Proactive Modeling Engine results in an Average Reciprocal Hit-Rank (ARHR) of 0.871. Likewise, the integration results in System Usability Scale (SUS) rating of 77. Finally, user feedback shows that the integration of the recommender system to the Proactive Modeling Engine increases the usability and learnability of domain-speci c modeling tools.

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