bluuebunny/crossref_metadata_2025_split huggingface dataset:
Towards Assembly-Free Methods for Additive Manufacturing Simulation
Authors: Krishnakumar Anirudh , Suresh Krishnan , Chandrasekar Aaditya 
Published: January 2016

There is significant interest today in the finite element simulation of various Additive Manufacturing (AM) processes. AM simulation is time-dependent, inherently non-linear, and involves multiple physics. In addition, repeated meshing and insertion of new elements during material deposition can pose significant implementation challenges.
Currently, AM simulation is handled either through a ‘quiet’ approach or an ‘inactive’ approach. In the quiet approach, all finite elements within the workspace are assembled into the global stiffness matrix, and the elements yet to be deposited are assigned ‘void’ material properties. In the inactive approach, only the elements that have been deposited are assembled into the global stiffness matrix. The advantages and disadvantages of the two methods are well documented.
In this paper, we propose a voxel-based, assembly-free framework for AM simulation. This framework presents several advantages including. (1) The workspace is meshed only once at the start of the simulation, (2) addition and deletion of elements is trivial, (3) reduced memory requirement as the global stiffness matrix is never assembled and (4) the underlying linear systems of equations can be solved efficiently through assembly-free methods. We demonstrate the framework here by simulating transient non-linear thermal behaviour of a laser deposition process, with material deposition.
Usability Demonstration of the G.EN.ESI Eco-Design Platform: The Cooker Hood Case Study
Authors: Germani Michele , Mandolini Marco , Marconi Marco , Rossi Marta 
Published: January 2016

Due to the increasing pressure of legislations and market, the environmental sustainability is becoming a key competitive factor for companies. In specific markets, as the Northern Europe one, customers are very careful on the quality and sustainability of products, thus companies has to design and manufacture green goods. In this context, there is a strong need of effective design tools and platform which allows to configure products applying the life cycle paradigm and with the “environment on mind”. Currently in the market there are only few examples of products designed taking into account the eco-design concepts. In particular, for mechatronic or energy using products only the use phase is usually considered and all the re-design strategies aim to reduce the energy consumption. This is essentially due to the fact that there is a lack of tools and design platforms, which are easy to use and well integrated with the traditional design tools and with the design processes of companies.
This paper wants to demonstrate the usefulness of a set of interoperable eco-design tools, the G.EN.ESI platform, in supporting the re-design of a mechatronic product. The proposed case study, realized in collaboration with an Italian leading company in the sector of household appliances, focuses on the improvement of a domestic cooker hood with the final objective to obtain a more sustainable product. The in-depth experimentation, for the duration of more than 3 months, involved different stakeholders within the company (designers, environmental expert, etc.), with the aim to validate the G.EN.ESI platform tools in different phases of the re-design process. The case study showed that the use of the platform has supported the company in the identification of the environmental hot-spots and during the product re-design phase, considering the whole life cycle. The re-engineered cooker hood exhibits relevant improvements in the most important environmental and economic indicators (environmental impact, energy efficiency, disassemblability, recyclability, etc.). Also a detailed analysis of the platform usability has been performed in order to measure if the tools completely fulfil the expectations of the final users. Finally, the level of integration within the company processes has been evaluated with a dedicated questionnaire. The results of these last analyses showed that the G.EN.ESI platform is appropriate to support a company to improve the sustainability of their products without the needs to heavily alter the traditional design process.
Automated Import of XML-Files Containing Optimized Geometric Data to 3D-CAD-Models of Non-Linear Integral Bifurcated Sheet Metal Parts
Authors: Weber Martins Thiago , Albrecht Katharina , Anderl Reiner 
Published: January 2016

The Collaborative Research Centre 666 has the focus on researching fundamental new methods for the development of optimized products and production processes for integral bifurcated sheet metal parts. Technological innovations have been achieved with respect to new production processes such as linear flow splitting and linear bend splitting as well as to produce products with flexible profiles.
The use of state of art product development methodologies can be applied but these are not optimized to deal with the high complexity of the requirements and properties of integral bifurcated sheet metal products. In order to deal with that complexity a new approach of a product development methodology, the algorithm based product development process, has been established. Within the scope of the algorithm based product development methodology a topology optimization, based on mathematical algorithms using product requirements information, is already applied in the conceptual steps of product development process. By using this methodological approach an optimized concept of bifurcated sheet metal can be determined. The results are stored as optimized geometric data in XML-format files. 3D-CAD-Models are generated based on these data.
However the import of these data into 3D-CAD-Systems are not fully automated. The developed data model, from earlier works for linear flow splitting and linear bend splitting, does not take into account the variability of the profiles in the third-dimension. In addition the topology optimization does not provide production-orientated design requirements and therefore it does not take into account the production process limits (of linear flow splitting and linear bend splitting). Hence 3D-CAD-Models resulting from the optimized geometric data need to be adapted manually.
Therefore new advanced approaches in terms of virtual product development tools need to be explored. This paper describes the development of an interface within the CAD-System Siemens NX which supports the automatic import of XML-files containing the optimized geometric data of non-linear integral bifurcated sheet metal in 3D-CAD-Models. The existing data model is extended considering the requirements of the developed interface in order to represent nonlinear bifurcated profiles. An approach of the interface using the described data model and the NX Open API is introduced and explained.
Combinatorial Method for Checking Stability in Tensegrity Structures
Authors: Cahan Daniel , Shai Offer 
Published: January 2016

Tensegrity structures have a great value in the academia and in industry, in particular for adjustable tensegrity structures that can sustain external forces when deployed. The main problem with the latter systems is checking their stability during deployment. One of the most famous methods for checking stability was developed 20 years ago by two mathematicians [1]. They showed that if the tensegrity structure is redundant then the check is simple. But if it is a determinate tensegrity structure then there is a need to calculate the velocities of all the joints and then after matrix multiplications a scalar is obtained. If the scalar is negative then it is concluded that the tensegrity system is unstable without knowing which element causes the problem and what should be done in order to stabilize it.
This paper proves that if the structure is a minimal rigid determinate structure, named Assur Graph, then there is a simple method for checking the stability. The proposed method suggests to remove a cable, calculate the curvature radius of one its inner joint and then conclude whether the structure is stable or not. In case that it was concluded that the system is unstable, then to shorten the cable so it becomes stable.
The main topic from the combinatorial method being used in this paper is the special properties of Assur Graphs, in particular their singular positions. It is proved that from all the determinate structures only the Assur Graphs have these special singular properties, upon which the proposed method and the proof relies on.
Integrated Capture and Representation of Product Information in Computer-Aided Product Development
Authors: Lejon Erik , Lundin Michael , Dagman Andreas , Jeppsson Peter , Näsström Mats 
Published: January 2016

This paper features the implementation and evaluation of a proposed approach for information capture and representation integrated into the existing design environments at two manufacturing companies. A tool has been developed that automatically derives information from the CAD system during design and provides users with the means to capture product information that has previously been documented outside of the CAD system. Product information is managed in a PLM data model and becomes, once stored, the foundation for providing tailored views of information.
Feedback from the evaluation shows that the prescribed approach was preferred to the current one and that it would likely provide value to users, both authors and consumers, of product information. This approach can reduce the time required to capture the pertinent product information. However, the primary savings are likely to be indirect as a result of increased consistency, understanding, and the potential (re)use of product information.
The approach and tools presented constitute another step toward providing each stakeholder with more efficient, intuitive, contextual, and purposeful support for information capture and representation in computer-aided product development.
Visualization of Headlight Illumination for the Virtual Prototyping of Light-Based Driver Assistance Systems
Authors: Berssenbrügge Jan , Trächtler Ansgar , Schmidt Christoph 
Published: January 2016

Driving simulators that are capable of a simulation of a virtual drive at night are increasingly used for the virtual prototyping of light-based driver assistance systems. Here, the interplay between driver and assistance system, which enhances the illumination of the road ahead of the vehicle, is investigated. For such investigations, special driving simulators are applied that enable not only a standard driving simulation but also cover the special requirements for the visualization of a driving scenery at night, the simulation of automotive headlights during a virtual drive at night, and the interface to a headlight control module (HCM) that operates the physical headlight prototypes.
In this paper, we present the visualization system of the reconfigurable driving simulator from the research project TRAFFIS. We describe the special application focus on the virtual prototyping of a light-based driver assistance system from our project partner Varroc Lighting Systems. The light-based DAS bases on a headlight prototype that combines a glare-free high beam (GFHB) function and a predictive adaptive frontlighting system (PAFS) for glare-free driving with maximized headlight time.
A Cooperative Driving NLMPC for Real Time Collision Avoidance
Authors: Rosolia Ugo , Braghin Francesco , Sabbioni Edoardo , Alleyne Andrew , De Bruyne Stijn 
Published: January 2016

A decentralized cooperative driving Non Linear Model Predictive Control (NLMPC) approach for path following and collision avoidance is presented in this paper.
The proposed decentralized approach is based on an information network, which communicates when two or more vehicles are near and so they might collide. In the case in which vehicles are far, online trajectory control is independently computed on-board by means of a NLMPC. When two or more vehicles get closer, trajectory control is no more independently carried out: optimal solution for these vehicles is coupled and thus their trajectories are computed dependently.
Performance of the proposed decentralized NLMPC for cooperative driving was assessed through numerical simulations involving two vehicles. Results were compared with ones of a centralized approach to assess optimality of the solution.
A Mathematical Model for Pressure Compensating Emitters
Authors: Taylor Katherine A. , Shamshery Pulkit , Wang Ruo-Qian , Winter Amos G. 
Published: January 2016

This paper presents a mathematical model investigating the physics behind pressure-compensating (PC) drip irrigation emitters. A network of PC emitters, commonly known as drip irrigation, is an efficient way to deliver water to crops while increasing yield. Irrigation can provide a means for farmer to grow more sensitive, and profitable crops and help billions of small-holder farmers lift themselves out of poverty. Making drip irrigation accessible and economically viable is important for developing farmers as most face the challenges of water scarcity, declining water tables and lack of access to an electrical grid. One of the main reasons for the low adoption rate of drip irrigation in the developing world is the relatively high cost of the pumping power. It is possible to reduce this cost by reducing the required activation pressure of the emitters, while maintaining the PC behavior. The work presented here provides a guide of how design changes in the emitter could allow for a reduction in the activation pressure from 1 bar to approximately 0.1 bar. This decrease in the activation pressure of each emitter in turn decreases the system driving pressure. This reduction of driving pressure will decrease the energy need of pumping, making a solar-powered system affordable for small-acreage farmers.
This paper develops a mathematical model to describe the PC behavior in a commercially available emitter. It is a 2D model that explains the relationship between the pressure, structural deformation and fluid flow within a PC emitter. A parametric study has been performed to understand the effects of geometric and material parameters with regards to the activation pressure and PC behavior. This knowledge will help guide the designs and prototypes of optimized emitters with a lower activation pressure, while also providing the PC behavior.
Towards an Integrated Data Schema Design for Additive Manufacturing: Conceptual Modeling
Authors: Lu Yan , Choi Sangsu , Witherell Paul 
Published: January 2016

Large amounts of data are generated, exchanged, and used during an additive manufacturing (AM) build. While the AM data from a single build is essential for establishing part traceability, when methodically collected, the full processing history of thousands of components can be mined to advance our understanding of AM processes. Hence, this full body of data must be captured, stored, and properly managed for easy query and analysis. An innovative, AM-specific data model is necessary for establishing of a comprehensive AM information management system.
This paper introduces our work towards designing a complete and integrated data model for AM processes. We begin by defining the scope and specifying the requirements of such a data schema. We investigate how information created and exchanged in the AM process chain is identified based on an AM process activity diagram. A comprehensive survey shows that existing AM standards are unable to provide both the breadth and the depth needed for an integrated AM information model. We propose a conceptual design for an additive manufacturing integrated data model, AMIDM, based on a well-defined product lifecycle management (PLM) data modeling method called PPR (product, process, and resource). The proposed AM model has a core scheme composed of product, process, and resource entities. The process entities play critical roles in transforming product input into product output using assigned resources such as equipment, material, personnel, and software tools. The proposed model has been applied to an information system design for Powder Bed Fusion based AM experimental data management. An XML (eXtensible Markup Language) schema is presented in the paper to demonstrate the effectiveness of the conceptual model.
Development of a Servohydraulic Roller Test Bench for Indoor Evaluation of the Vibrational Comfort of Bicycle Components
Authors: Petrone Nicola , Trabacchin Francesco , Panizzolo Fausto 
Published: January 2016

One of the most important parameters evaluated by racing and trekking cyclists is vibrational comfort: as generally accepted, it is closely correlated to the response of bicycle components in combination with the cyclist’s characteristics.
Vibration transmissibility of wheels and saddles was recently studied during lab tests using a wooden dummy bottom resting on the saddle or in road tests on an instrumented racing bicycle at different speeds on different surfaces.
The use of shakers is also well established in the evaluation of cyclist’s posture effects on the overall bicycle behaviour. In fact, in previous works, either a servohydraulic actuator was applied to the seatpost of a bicycle frame hinged at the front wheel axle with a cycling tester, or two electrodynamic shakers were applied under the wheels of a fully equipped bicycle, with a cyclist sitting statically on the saddle. In the present study, the combination of a servohydraulic actuator and a roller type bench allowed to overcome the limitations of the former experiences. Random vibrations were input to the bicycle-cyclist complex by means of rollers supporting the rear wheel while cyclists were cycling unrestrained on the rollers. The test bench setup and tuning approach are presented for comparison with results available from previous bench and road tests.
Verification of Models of Personal Perception of Faces by Closed-Eye Classifier Using Histogram Correlation
Authors: Romero J. , Diago L. , Shinoda J. , Hagiwara I. 
Published: January 2016

People rapidly form impressions from facial appearance, and these impressions affect social decisions. Data-driven, computational models are the best available tools for identifying the source of such impressions. However, the computational models cannot be accepted unless they have passed the tests of validation to ascertain their credibility.
In this paper, the condition of the eyes of the person is used to validate the fuzzy rules extracted from the computational models. A simple and effective classifier is proposed to evaluate the closeness of the eyes during the evaluation of a small database of portraits. The experimental results show that closed-eyes can be detected only after the proposed shift of the normalized histogram is applied. Although it is very simple, the proposed classifier can achieve better accuracy than other state of the art classifiers. The relationship between the closeness of the eyes and the evaluation of the subjects is also analyzed.
A novel perfused Bloch–McConnell simulator for analyzing the accuracy of dynamic hyperpolarized MRS
Authors: Walker Christopher M. , Chen Yunyun , Lai Stephen Y. , Bankson James A. 
Published: January 2016

Purpose:Magnetic resonance spectroscopy of hyperpolarized agents allows real‐time detection of metabolism in vivo. However, the nonrenewable nature of these signals necessitates data acquisitions that differ significantly from conventional magnetic resonance imaging. Signal evolution is permanently altered by the data acquisition scheme, potentially leading to sequence parameter‐dependent bias in quantification. The authors have developed a novel simulation environment to characterize the effects of sequence parameters on magnetic resonance spectroscopy‐based chemical exchange measurements using hyperpolarized pyruvate.Methods:Conventional Bloch–McConnell equations were coupled with a pharmacokinetic model for perfusion to allow realistic simulation of in vivo dynamic hyperpolarized signal evolution. In this study, simulations were conducted to explore effects of excitation angle and repetition time on the observed signal and subsequent parametric analysis. Both high and low apparent exchange rates were modeled under assumption of both perfused and closed systems. Bias due to sampling strategy bias was subsequently tested in vivo.Results:Simulation of dynamic magnetic resonance spectroscopy studies using hyperpolarized pyruvate demonstrated that for closed systems, accurate measurement of the apparent exchange rate was possible over a wide range of sequence parameters. This was true for both high and low apparent exchange rates, although a low exchange rate was associated with larger errors when excitation angles were high. When effects of perfusion were included to account for pyruvate delivery, a more restricted range of settings led to accurate quantification of exchange rates. Perfusion alleviated some of the errors seen at high excitation angles for low exchange rates. Residuals from parametric analysis did not generally correlate with fit accuracy, implying that the quality of the analysis model was not a major driver of error. Animal studies acquired with sequence parameters that are predicted to impart bias showed a significant under estimation of exchange rates (P < 0.035) compared to parameter combinations that are not expected to bias measurements.Conclusions:The authors' results suggest that great care must be taken when measuring dynamic processes by magnetic resonance spectroscopy of hyperpolarized substrates. When comparing apparent exchange rates, choice of sequence parameters will affect the results. Bias introduced by parameters of more advanced acquisition and reconstruction schemes will likely increase compared to the relatively simple dynamic spectroscopy methods tested herein. The modified Bloch–McConnell equations the authors describe will be crucial tools for characterizing and optimizing the performance of these more advanced techniques.
Novel Genes Related to Ceftriaxone Resistance Found among Ceftriaxone-Resistant Neisseria gonorrhoeae Strains Selected
In Vitro
Authors: Gong Zijian , Lai Wei , Liu Min , Hua Zhengshuang , Sun Yayin , Xu Qingfang , Xia Yue , Zhao Yue , Xie Xiaoyuan 
Published: January 2016

ABSTRACT

The emergence of ceftriaxone-resistant
Neisseria gonorrhoeae
is currently a global public health concern. However, the mechanism of ceftriaxone resistance is not yet fully understood. To investigate the potential genes related to ceftriaxone resistance in
Neisseria gonorrhoeae
, we subcultured six gonococcal strains with increasing concentrations of ceftriaxone and isolated the strains that became resistant. After analyzing several frequently reported genes involved in ceftriaxone resistance, we found only a single mutation in
penA
(A501V). However, differential analysis of the genomes and transcriptomes between pre- and postselection strains revealed many other mutated genes as well as up- and downregulated genes. Transformation of the mutated
penA
gene into nonresistant strains increased the MIC between 2.0- and 5.3-fold, and transformation of mutated
ftsX
increased the MIC between 3.3- and 13.3-fold. Genes encoding the ABC transporters FarB, Tfq, Hfq, and ExbB were overexpressed, while
pilM
,
pilN
, and
pilQ
were downregulated. Furthermore, the resistant strain developed cross-resistance to penicillin and cefuroxime, had an increased biochemical metabolic rate, and presented fitness defects such as prolonged growth time and downregulated PilMNQ. In conclusion, antimicrobial pressure could result in the emergence of ceftriaxone resistance, and the evolution of resistance of
Neisseria gonorrhoeae
to ceftriaxone is a complicated process at both the pretranscriptional and posttranscriptional levels, involving several resistance mechanisms of increased efflux and decreased entry.