bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parametric Quantile Regression Based on the Generalized Gamma Distribution
Authors: Noufaily Angela , Jones M. C. 
Published: September 2013

SummaryWe explore a particular fully parametric approach to quantile regression and show that this approach can be very successful. Motivated by the provision of reference charts, we work in the specific context of a positive response variable, whose conditional distribution is modelled by the generalized gamma distribution, and a single covariate, the dependence of parameters of the generalized gamma distribution on which is through simple linear and log-linear forms. With only six parameters at most, such models allow a perhaps surprisingly wide range of distributional shapes that seems adequate for many practical situations. We show that maximum likelihood estimation of the models is computationally quite straightforward, that the estimated quantiles behave well, that use of standard maximum likelihood asymptotics to perform likelihood ratio tests of the number of parameters needed and to give pointwise confidence bands based on the expected information matrix are reliable in this context, and we more tentatively provide a simple goodness-of-fit test of the whole model. Two data analyses, from the health and environmental spheres, are included, along with simulation results. We claim that quite a direct parametric maximum likelihood approach like this—which also obviates the problem of quantile crossing—is adequate for many situations, and there is less need than one might think to resort to more complicated semiparametric and non-parametric approaches to quantile regression in practice.
Accounting for Spatially Varying Directional Effects in Spatial Covariance Structures
Authors: Neto Joaquim Henriques Vianna , Schmidt Alexandra M. , Guttorp Peter 
Published: September 2013

Summary
Wind direction plays an important role in the spread of air pollutants over a geographical region. We discuss how to include wind directional information in the covariance function of spatial models. Our models are based on a constructive convolution approach, wherein a spatial process is described as a convolution between a spatially varying smoothing kernel and a white noise process. We describe two different ways of accounting for wind direction: one makes use of a non-stationary version of the Matérn covariance function and the other a kernel function that resembles the exponential correlation function. We fit the models proposed to ground level ozone observed at a monitoring network in north-eastern USA. We compare our wind-based covariance models with three other models: two that make use of standard covariance functions, and one whose kernel function varies across space according to latent spatial processes. The inference procedure is performed under the Bayesian paradigm, and uncertainty about parameter estimation is naturally accounted for when performing spatial interpolation. Samples from the posterior distribution under our proposed models are obtained much faster when compared with the model based on latent spatial processes. Although fitted values that are obtained under our proposed models and those obtained based on latent processes are quite similar, our models provided smaller ranges of the predictive posterior credible intervals.
Method for the Creation of a Six Bar Linkage to Simultaneously Carry Two Rigid Bodies Through Four Coordinated Positions
Authors: Zimmerman Ronald A. 
Published: September 2013

A method for the creation of a six bar linkage with two ground pivots to simultaneously carry two rigid bodies through four coordinated positions was invented and is described and illustrated herein.
Type synthesis was used to identify possible linkage classes and specific types of possible six bar linkages. A linkage synthesis method which superimposes three Burmester center point curves to create a six bar linkage mechanism with two ground pivots, to carry two coupled rigid bodies simultaneously through four specified, coordinated positions was developed and is demonstrated. An extension of the method to carry two non-coupled rigid bodies through four positions is indicated.
This method was invented in the process of developing a 2nd row automotive truck seat, which is used as an example to illustrate the procedure.
A six bar linkage which carries an automotive truck seat back and seat cushion through four coordinated positions is shown.
Probabilistic Certificate of Correctness for Cyber Physical Systems
Authors: Van der Velden Alex , Koch Patrick , Devanathan Srikanth , Haan Jeff , Naehring Dave , Fox David 
Published: September 2013

Cyber Physical Systems couple computational and physical elements, therefore the behavior of geometry (deformations, kinematics), physics and controls needs to be certified using many different tools over a very high dimensional space. Because of the near infinite number of ways such a system can fail meeting its requirements, we developed a Probabilistic Certificate of Correctness (PCC) metric which quantifies the probability of satisfying requirements with consistent statistical confidence.
PCC can be implemented as a scalable engineering practice for certifying complex system behavior at every milestone in the product lifecycle. This is achieved by: creating virtual prototypes at different levels of model abstraction and fidelity; capturing and integrating these models into a simulation process flow; verifying requirements in parallel by deploying virtual prototypes across large organizations; reducing certification time proportional to additional computational resources and trading off sizing, modeling accuracy, technology and manufacturing tolerances against requirements and cost.
This process is an improvement over the V-cycle because verification and validation happens at every stage of the system engineering process thus reducing rework in the more expensive implementation and physical certification phase. The PCC process is illustrated using the example of “Safe Range” certification for an UAV with active flutter control.
Compliant Constant-Force Micro-Mechanism for Enabling Dual-Stage Motion
Authors: Zirbel Shannon A. , Aten Quentin T. , Easter Melanie , Jensen Brian D. , Howell Larry L. 
Published: September 2013

This paper describes a fully compliant constant-force micro-mechanism that enables dual-stage motion for nanoinjection. Nanoinjection is a recently developed process for delivering DNA into mouse zygotes via electrostatic accumulation and release of the DNA onto a microelectromechanical system (MEMS) lance.
The fully compliant constant-force nanoinjector is a concatenation of two separate mechanisms: a six-bar mechanism with compliant lamina-emergent torsional (LET) joints to raise the lance, and a pair of constant-force crank-sliders with LET joints positioned on either side of the six-bar mechanism to drive the lance forward.
The fully compliant nanoinjector exhibits self-reconfiguring metamorphic motion to first raise the lance to the midline of the zygote and then translate the lance forward with a controlled motion. This dual-stage motion is necessary for the lance to pierce the zygote without causing damage to the cell membrane.
The device achieves two sequential displacement behaviors in a compliant mechanism fabricated from a single, continuous piece of material.
A Graph Grammar Based Approach to Automated Manufacturing Planning
Authors: Fu Wentao , Eftekharian Ata A. , Radhakrishnan Pradeep , Campbell Matthew I. , Fritz Christian 
Published: September 2013

In this paper, a new graph grammar representation is proposed to reason about the manufacturability of solid models. The knowledge captured in the graph grammar rules serves as a virtual machinist in its ability to recognize arbitrary geometries and match them to various machine operations. Firstly, a given part is decomposed into multiple sub-volumes, where each sub-volume is assumed to be machined in one operation or to be non-machinable. The decomposed part is converted into a graph so that graph grammar rules can determine the machining details. For each operation, rules determine the face on the part that the tool enters, the type of tools used, the type of machine used, and how the part is fixed within the machine. A candidate plan is a feasible sequence of all of the necessary machining operations needed to manufacture this part. If a given geometry is not machinable, the rules will fail to find operations for all of the partitions.
As a result of this representation, designers can quickly get insights into how a part can be made and how it can be improved (e.g. change features to reduce time and cost). A variety of tests of this algorithm on both simple and complex engineering parts show its effectiveness and efficiency.
Scenario-Based Learning Environment to Support Peer-Learning
Authors: Siddique Zahed , Saha Mrinal C. , Akasheh Firas , Arif Shaiful , Barua Bipul , Hurdelbrink Keith 
Published: September 2013

It is well documented that students learn more effectively when they are actively involved in the learning process, and interacting with peers. Interactive scenario-based education is a novel concept expected to stimulate active learning and provide a peer-learning experience. In this paper we present Create your Scenario Interactively (CSI) module, which is an interactive storybook-like learning tool composed of interactive storyline, 2D/3D visualization, simulation, and state-of-the-art interaction technology. The CSI method allows peer-interactions and prepares students to solve open-ended problems.
The CSI module has been developed for metal casting and implemented in manufacturing engineering courses at the University of Oklahoma and Tuskegee University. In this paper, we discuss the impact of the CSI on students’ learning in manufacturing engineering education. Our preliminary results suggest that a majority of the students feels that the CSI module is very effective in keeping them engaged. We also analyze the effect of peer-learning to develop critical thinking and solve design problems. The details of the CSI module, implementation details, and assessment results are discussed in the paper.
Body in White Geometry Measurements of Non-Rigid Components: A Virtual Perspective
Authors: Lindau Björn , Andersson Alf , Lindkvist Lars , Söderberg Rikard 
Published: September 2013

Increased use of virtual assembly tools within automotive industry places new demands on available geometry information. Unfortunately, the measurement results of non-rigid components depend heavily on the locating schemes used in the measurement fixtures. Non-rigid component measurements are mostly performed in an over-constrained condition, describing the shapes of the parts as presented in assembly processes or as mounted on nominal products. With these kinds of measurements, there is an information loss regarding the actual springback shapes in the stored historical geometry data. Knowledge about the components’ shapes after springback is vital for virtual non-rigid fault propagation analysis.
The objective of this paper is to show the possibilities for presenting the measurement results of components as they were over-constrained, even if the parts were measured in a constrained condition (in practice limited constrained). The aim is to minimize the information loss, to spare measurement resources and to allow for better use of inspection data in assembly simulations. Predicted over-constrained measurement results in the presented cases bear reasonably good resemblance to measured over-constrained conditions when the two are compared. The ability to present both constrained and over-constrained results from one measurement setup will spare measurement resources and improve conditions for further virtual analysis and support. Furthermore, the presented cases verify the use of Method of Influence Coefficients (MIC) in the clamping step.
Development of the Next-Generation Computational Fracture Mechanics Simulator on the Earth Simulator 2
Authors: Yodo Kaworu , Kawai Hiroshi , Okada Hiroshi , Ogino Masao , Shioya Ryuji 
Published: September 2013

Fracture mechanics analysis using the finite element method has been one of the key methodologies to evaluate structural integrity for aging infrastructures such as aircraft, ship, power plants, etc. However, three-dimensional crack analyses for structures with highly complex three-dimensional shapes have not widely been used, because of many technical difficulties such as the lack of enough computational power.
The authors have been developing a fracture mechanics analysis system that can deal with arbitrary shaped cracks in three-dimensional structures. The system consists of mesh generation software, a finite element analysis program and a fracture mechanics module. In our system, a Virtual Crack Closure-Integral Method (VCCM) for the quadratic tetrahedral finite elements is adopted to evaluate the stress intensity factors. This system can perform the three-dimensional fracture analyses. Fatigue and SCC crack propagation analyses with more than one cracks of arbitrary complicated shapes and orientations. The rate and direction of crack propagation are predicted by using appropriate formulae based on the stress intensity factors.
When the fracture mechanics analysis system is applied to the complex shaped aging structures with the cracks which are modeled explicitly, the size of finite element analysis tends to be very large. Therefore, a large scale parallel structural analysis code is required. We also have been developing an open-source CAE system, ADVENTURE. It is based on the hierarchical domain decomposition method (HDDM) with the balancing domain decomposition (BDD) pre-conditioner. A general-purpose parallel structural analysis solver, ADVENTURE_Solid is one of the solver modules of the ADVENTURE system.
In this paper, we combined VCCM for the tetrahedral finite element with ADVENTURE system and large-scale fracture analyses are fully automated. They are performed using the massively parallel super computer ES2 (Earth Simulator 2) which is owned and run by JAMSTEC (Japan Agency for Marine-Earth Science and Technology).
Dynamic Effects of Electrical Pitting in Steam-Turbine Tilting-Pad Thrust-Bearings
Authors: Pennacchi P. , Ricci R. , Chatterton S. , Borghesani P. , Vania A. , D’Antona G. , Pensieri C. , Rolla C. 
Published: September 2013

This paper merges the analysis of a case history and the simplified theoretical model related to a rather singular phenomenon that may happen in rotating machinery. Starting from the first, a small industrial steam turbine experienced a very strange behavior during megawatt load. When the unit was approaching the maximum allowed power, the temperature of the babbitt metal of the pads of the thrust bearing showed constant increase with an unrecoverable drift. Bearing inspection showed that pad trailing edge had the typical aspect of electrical pitting. This kind of damage was not reparable and bearing pads had to replaced. This problem occurred several times in sequence and was solved only by adding further ground brushes to the shaft-line. Failure analysis indicated electrodischarge machining as the root fault.
A specific model, able to take into consideration the effect of electrical pitting and loading capacity decreasing as a consequence of the damage of the babbitt metal, is proposed in the paper and shows that the phenomenon causes the irretrievable failure of the thrust bearing.
Developing Competencies for the 21st Century Engineer
Authors: Hawthorne Bryant , Sha Zhenghui , Panchal Jitesh H. , Mistree Farrokh 
Published: September 2013

This is the second paper in a four-part series focused on a competency-based approach for personalized education in a group setting. In the first paper, we focus on identifying the competencies and meta-competencies required for the 21st century engineers. In this paper, we provide an overview of an approach to developing competencies needed for the fast changing world and allowing the students to be in charge of their own learning. The approach fosters “learning how to learn” in a collaborative environment. We believe that two of the core competencies required for success in the dynamically changing workplace are the abilities to identify and manage dilemmas. In the third paper, we discuss our approach for helping students learn how to identify dilemmas in the context of an energy policy design problem. The fourth paper is focused on approaches to developing the competency to manage dilemmas associated with the realization of complex, sustainable, socio-techno-eco systems.
The approach is presented in the context of a graduate-level course jointly offered at University of Oklahoma, Norman and Washington State University, Pullman during Fall 2011. The students were asked to identify the competencies needed to be successful at creating value in a culturally diverse, distributed engineering world at the beginning of the semester. The students developed these competencies by completing various assignments designed to collaboratively answer a Question for Semester (Q4S). The Q4S was focused on identifying and managing dilemmas associated with energy policy and the next generation bridging fuels. A unique aspect of this course is the collaborative structure in which students completed these assignments individually, in university groups and in collaborative university teams. The group and team structures were developed to ultimately aid individual learning. The details of the answer to the Q4S are elaborated in the other three papers which address identifying and managing dilemmas, specifically related to Feed-In-Tariff (FIT) policy and bridging fuels.
The fundamental principles of our approach include a shift in the role of the instructor to orchestrators of learning, shift in the role of students to active learners, providing opportunities to learn, shift in focus from lower levels to upper levels of learning, creation of learning communities, embedding flexibility in courses, leveraging diversity, making students aware of the learning process, and scaffolding. Building on our experience in the course, we discuss specific ways to foster the development of learning organizations within classroom settings. Additionally, we present techniques for scaffolding the learning activities in a distributed classroom based on systems thinking, personal mastery, mental models, a shared vision, and team learning. The approach enables personalized learning of individuals in a group setting.
Assessing the Use of Function Models and Interaction Models Through Concept Sketching
Authors: Caldwell Benjamin W. , Ramachandran Raveesh , Mocko Gregory M. 
Published: September 2013

Functional representations are often used in the conceptual stages of design because they encourage the designer to focus on the intended use and purpose of a system rather than the physical solution. Function models have been proposed by many researchers as a tool to expand the solution search space and guide concept generation, and many design tools have been created to support function-based design. These tools require designers to create function models of new or existing artifacts, but there is limited published research describing the level of functional detail that should be included in a model or the appropriate level of abstraction to model artifacts. Further, there is limited experimental evidence that designers use function models when generating concepts, and controlled experiments in the literature have focused on ideation rather than function models. Therefore, this research focuses on how artifacts should be modeled to guide concept generation in conceptual design.
In this research, three artifact representations are studied: function models, interaction models, and pruned function models. A user study was conducted in which participants were asked to design a new device based on a problem statement, a set of requirements, and a treatment. Participants were randomly assigned a treatment of a function model, interaction model, pruned model, or no model. A conformance metric was developed to measure the extent to which participants used a model when generating concept sketches. The results show that the functional conformance of participants using a pruned model is approximately 40% higher than that of participants using a function model. These results demonstrate that the use of a specific level of functional detail improves the use of functions within the model for concept generation.
Analysis of risk factors for death after blunt traumatic rupture of the thoracic aorta
Authors: Franzen Daniel , Genoni Michele 
Published: September 2013

Traumatic aortic rupture (TAR) is a rare but serious injury, leading to death at the scene in most cases. Between 1990 and 2003, all consecutive patients and victims with TAR were retrospectively analysed by reviewing hospital and autopsy records. Univariate and multivariate Cox regression analyses were performed to define determinants of mortality. During the study period, a total of 85 patients (70 men, mean age 47±18.8 years) with TAR were observed in the greater area of Zurich giving a population-based rate of 0.6 cases per 100 000 persons per year. Prehospital, in-hospital and overall mortalities were 40.0%, 31.4% and 58.8%, respectively, with a median survival time of 2 days (IQR 1–3617 days). In the univariate analysis, significant determinants of prehospital and overall mortality were age (HR 1.05, p=0.006), complete aortic transection (HR 7.17, p=0.003), number (HR 1.35, p=0.009) and associated injuries to chest (HR 3.41, p=0.03), liver (HR 6.00, p=0.002) and spine (HR 5.19, p=0.01). By comparison, risk factors for in-hospital mortality included haemodynamic instability upon arrival in the emergency room (HR 16.11, p<0.001) and open surgical repair (HR 14.29, p=0.02). In the multivariate model, only age (p=0.02) and complete aortic transection (p=0.001) were significant determinants of mortality. Therefore, with the exception of complete aortic transection, risk factors of prehospital and in-hospital death in patients with TAR differ greatly. The in-hospital mortality was not affected by the number or localisation of associated injuries, whereas haemodynamic instability and open aortic repair seem to predict in-hospital mortality after TAR.Clinical Trial RegistrationNCT01632774.