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1.
Participating media with an inhomogeneous index of refraction make light follow curved paths. Simulating this in a global
illumination environment has usually been neglected due to the complexity of the calculations involved, sacrificing accurate
physical simulations for efficient visual results.
This paper aims to simulate non-linear media in a more reasonable time than previous works without losing physical correctness.
Accuracy is achieved by solving the Eikonal equation of geometrical optics, which describes the path followed by a light beam
that traverses a non-linear medium. This equation is used in the context of a photon mapping extension. 相似文献
2.
José Hernández-Orallo Cèsar Ferri Nicolas Lachiche Adolfo Martínez-Usó M. José Ramírez-Quintana 《Data mining and knowledge discovery》2016,30(4):848-890
Some supervised tasks are presented with a numerical output but decisions have to be made in a discrete, binarised, way, according to a particular cutoff. This binarised regression task is a very common situation that requires its own analysis, different from regression and classification—and ordinal regression. We first investigate the application cases in terms of the information about the distribution and range of the cutoffs and distinguish six possible scenarios, some of which are more common than others. Next, we study two basic approaches: the retraining approach, which discretises the training set whenever the cutoff is available and learns a new classifier from it, and the reframing approach, which learns a regression model and sets the cutoff when this is available during deployment. In order to assess the binarised regression task, we introduce context plots featuring error against cutoff. Two special cases are of interest, the \( UCE \) and \( OCE \) curves, showing that the area under the former is the mean absolute error and the latter is a new metric that is in between a ranking measure and a residual-based measure. A comprehensive evaluation of the retraining and reframing approaches is performed using a repository of binarised regression problems created on purpose, concluding that no method is clearly better than the other, except when the size of the training data is small. 相似文献
3.
One of the applications of workflow systems is the management of administrative processes characterized by the transmission
of information elements among users of an organization. Tasks contained in these processes are carried out by users responsible
for confirming, modifying or adding information throughout. These processes need to be defined in workflow management systems
in which all the elements are perfectly identified and are easily adaptable to changes that may arise in the sequences of
tasks, in the users involved or in the data transmitted from one task to another. For this kind of processes is easier to
reuse those represented in ontologies. On one hand, existing ontologies for representing some domain elements can be reused.
At the same time, ontologies have an excellent expressive capacity to define tasks, their relationships and the flow control
among them with precision. This paper proposes a complete model, together with the necessary software tools, for tackling
this issue.
álvaro E. Prieto is a teaching/research assistant professor of Computer Science at the University of Extremadura, Spain. He has an MSc in Computer Science from the University of Extremadura (2000). His Ph.D. research addresses the use of ontologies in workflows. He is currently involved in various national and regional R&D&I projects. Adolfo Lozano-Tello is teaching/research assistant professor of Computer Science Department at University of Extremadura, Spain. He is a Ph.D. (2002) with a special prize of extraordinary thesis about selection of ontologies for software applications. He has published more than 50 papers on the above issues on Software Engineering and Knowledge Engineering. 相似文献
álvaro E. PrietoEmail: |
álvaro E. Prieto is a teaching/research assistant professor of Computer Science at the University of Extremadura, Spain. He has an MSc in Computer Science from the University of Extremadura (2000). His Ph.D. research addresses the use of ontologies in workflows. He is currently involved in various national and regional R&D&I projects. Adolfo Lozano-Tello is teaching/research assistant professor of Computer Science Department at University of Extremadura, Spain. He is a Ph.D. (2002) with a special prize of extraordinary thesis about selection of ontologies for software applications. He has published more than 50 papers on the above issues on Software Engineering and Knowledge Engineering. 相似文献
4.
Criticality Analysis for Maintenance Purposes: A Study for Complex In‐service Engineering Assets 下载免费PDF全文
Adolfo Crespo Márquez Pedro Moreu de León Antonio Sola Rosique Juan F. Gómez Fernández 《Quality and Reliability Engineering International》2016,32(2):519-533
The purpose of this paper is to establish a basis for a criticality analysis, considered here as a prerequisite, a first required step to review the current maintenance programs, of complex in‐service engineering assets. Review is understood as a reality check, a testing of whether the current maintenance activities are well aligned to actual business objectives and needs. This paper describes an efficient and rational working process and a model resulting in a hierarchy of assets, based on risk analysis and cost–benefit principles, which will be ranked according to their importance for the business to meet specific goals. Starting from a multicriteria analysis, the proposed model converts relevant criteria impacting equipment criticality into a single score presenting the criticality level. Although detailed implementation of techniques like Root Cause Failure Analysis and Reliability Centered Maintenance will be recommended for further optimization of the maintenance activities, the reasons why criticality analysis deserves the attention of engineers and maintenance and reliability managers are precisely explained here. A case study is presented to help the reader understand the process and to operationalize the model. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
5.
The positive and negative influences of violent/action games, henceforth called “action games”, remains controversial in the scholarly literature. Although debate continues whether action games influence aggressive behavior, little research has examined the influence of action games on civic engagement. The current study addresses this gap by examining the correlation between exposure to action games on civic engagement and on-line prosocial behavior in a sample of 873 teenagers. Results indicated that girls as well as teens who had parents who were more technologically savvy tended to engage in more civic behaviors. Exposure to action games predicted more prosocial behavior on-line, but did not predict civic engagement either positively or negatively. However, exposure to action games and parental involvement interacted to promote youth civic engagement. Action-game-playing-youth whose parents were involved in game play and supervision were most civically involved, compared to youth who did not play action games, or whose parents were less involved. These results indicated little support for the belief that exposure to violence in video games decreases prosocial behavior and/or civic engagement. Conversely some support was found for the possibility that playing action games is associated with small increased prosocial behavior and civic engagement in the real world, possibly due to the team-oriented multiplayer options in many of these games. 相似文献
6.
Ibanez JG Vazquez-Olavarrieta JL Hernandez-Rivera L Garcia-Sanchez MA Garcia-Pintor E 《Water science and technology》2012,65(11):2079-2083
Electrocoagulation (EC) is a wastewater treatment process in which aqueous pollutants can be removed by adsorption, entrapment, precipitation or coalescence during a coagulation step produced by electrochemically generated metallic species. When using Fe as the sacrificial electrode, Fe(2+) and Fe(3+) ions are formed. As Fe(3+) species are paramagnetic, this property can in principle be used to facilitate their removal through the application of a magnetic field. In the present work we present a proof-of-concept for a combined electrochemical-magnetic method for pollutant removal. For this approach, the amounts of Fe(2+) and Fe(3+) produced in an EC cell at various voltages were measured by spectroscopic methods to confirm that Fe(3+) species predominate (up to 84%). The effectiveness of the presence of a magnetic field in the precipitation of coagulants from a suspension was confirmed by monitoring the turbidity change versus time with and without exposure to a magnetic field, up to a 30% improvement. 相似文献
7.
Elena Garces Adolfo Munoz Jorge Lopez‐Moreno Diego Gutierrez 《Computer Graphics Forum》2012,31(4):1415-1424
Decomposing an input image into its intrinsic shading and reflectance components is a long‐standing ill‐posed problem. We present a novel algorithm that requires no user strokes and works on a single image. Based on simple assumptions about its reflectance and luminance, we first find clusters of similar reflectance in the image, and build a linear system describing the connections and relations between them. Our assumptions are less restrictive than widely‐adopted Retinex‐based approaches, and can be further relaxed in conflicting situations. The resulting system is robust even in the presence of areas where our assumptions do not hold. We show a wide variety of results, including natural images, objects from the MIT dataset and texture images, along with several applications, proving the versatility of our method. 相似文献
8.
Adolfo Hernandez 《软件和集成电路》2022,(6):10-11
<正>和其他运营商相比,电信运营商向5G的过渡要更具挑战性。而通过拥抱云技术,电信运营商能够更好地克服5G技术带来的挑战,包括解决复杂的网络编排,整合新技术、应用和运营模式,开发运行新网络技能组合等。电信运营商正面临着多重挑战:一方面,他们必须开发更多的智能网络(包括边缘计算功能)以应对物联网(IoT)设备数量的快速增长,并研究如何确保5G的投资回报;另一方面,他们还需要应对新冠肺炎疫情造成的财务影响, 相似文献
9.
The effect of ultra-thin graphite on the morphology and physical properties of thermoplastic polyurethane elastomer composites 总被引:1,自引:0,他引:1
Olivia Menes Manuela Cano Adolfo Benedito Enrique Giménez Pere Castell Wolfgang K. Maser Ana M. Benito 《Composites Science and Technology》2012
Composites of thermoplastic polyurethane (TPU) and ultra-thin graphite (UTG) with concentrations ranging from 0.5 wt.% to 3 wt.% were prepared using a solution compounding strategy. Substantial reinforcing effects with increased loadings are achieved. Compared to neat TPU, values for storage modulus and shear viscosity are enhanced by 300% and 150%, respectively, for UTG concentrations of 3 wt.%. Additionally, an enhancement of thermal properties is accomplished. The crystallization temperature and thermal stability increased by 30 °C and 10 °C, respectively, compared to neat TPU. Furthermore, the use of oxidized UTG (UTGO) with its added functional oxygen groups suggests the presence of chemical interactions between UTG and TPU, which additionally impact on the thermal properties of the corresponding composites. Controlling the oxidation degree, thus offers further possibilities to obtain composites with tailored properties. The presented approach is straightforward, leads to homogeneous TPU-UTG composites with improved materials properties and is especially suitable for commercial UTG materials and further up-scaled production. 相似文献
10.
Thermal and electrical conductivity of melt mixed polycarbonate hybrid composites co‐filled with multi‐walled carbon nanotubes and graphene nanoplatelets 下载免费PDF全文
In this work, we present thermoplastic nanocomposites of polycarbonate (PC) matrix with hybrid nanofillers system formed by a melt‐mixing approach. Various concentrations of multi‐walled carbon nanotubes (MWCNT) and graphene nanoplatelets (GnP) were mixed in to PC and the melt was homogenized. The nanocomposites were compression molded and characterized by different techniques. Torque dependence on the nanofiller composition increased with the presence of carbon nanotubes. The synergy of carbon nanotubes and GnP showed exponential increase of thermal conductivity, which was compared to logarithmic increase for nanocomposite with no MWCNT. Decrease of Shore A hardness at elevated loads present for all investigated nanocomposites was correlated with the expected low homogeneity caused by a low shear during melt‐mixing. Mathematical model was used to calculate elastic modulus from Shore A tests results. Vicat softening temperature (VST) showed opposite pattern for hybrid nanocomposites and for PC‐MWCNT increasing in the latter case. Electrical conductivity boost was explained by the collective effect of high nanofiller loads and synergy of MWCNT and GnP. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42536. 相似文献