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31.
Mathematical simulation has been widely used in biomedical and biological sciences. In the case of the surface electromyographic (SEMG) activity, some models have been proposed aiming to study muscle contraction strategies that are used during different tasks and conditions. Most of SEMG simulators are based on energy modulation of a Gaussian noise. This work proposes a novel simulator in which the user-defined parameters are associated with the motor units (MUs) recruitment and their firing rate. Comparison between the mean spectrum of real SEMG signals collected in isometric contraction of the muscle biceps brachii and the mean spectrum obtained from simulated SEMG signals showed a good agreement, pointing the proposed simulator seems to be capable to generate consistent electromyographic signals in time and frequency domains and that can be used in many studies, in particular in the evaluation of automatic methods aimed to detect muscular contraction. 相似文献
32.
A general topology-based framework for adaptive insertion of cohesive elements in finite element meshes 总被引:1,自引:1,他引:0
Glaucio?H.?PaulinoEmail author Waldemar?Celes Rodrigo?Espinha Zhengyu??Zhang 《Engineering with Computers》2008,24(1):59-78
Large-scale simulation of separation phenomena in solids such as fracture, branching, and fragmentation requires a scalable
data structure representation of the evolving model. Modeling of such phenomena can be successfully accomplished by means
of cohesive models of fracture, which are versatile and effective tools for computational analysis. A common approach to insert
cohesive elements in finite element meshes consists of adding discrete special interfaces (cohesive elements) between bulk
elements. The insertion of cohesive elements along bulk element interfaces for fragmentation simulation imposes changes in
the topology of the mesh. This paper presents a unified topology-based framework for supporting adaptive fragmentation simulations,
being able to handle two- and three-dimensional models, with finite elements of any order. We represent the finite element
model using a compact and “complete” topological data structure, which is capable of retrieving all adjacency relationships
needed for the simulation. Moreover, we introduce a new topology-based algorithm that systematically classifies fractured
facets (i.e., facets along which fracture has occurred). The algorithm follows a set of procedures that consistently perform
all the topological changes needed to update the model. The proposed topology-based framework is general and ensures that
the model representation remains always valid during fragmentation, even when very complex crack patterns are involved. The
framework correctness and efficiency are illustrated by arbitrary insertion of cohesive elements in various finite element
meshes of self-similar geometries, including both two- and three-dimensional models. These computational tests clearly show
linear scaling in time, which is a key feature of the present data-structure representation. The effectiveness of the proposed
approach is also demonstrated by dynamic fracture analysis through finite element simulations of actual engineering problems.
相似文献
Glaucio H. PaulinoEmail: |
33.
André Stork Clemens-August Thole Stanislav Klimenko Igor Nikitin Lialia Nikitina Yuri Astakhov 《The Visual computer》2008,24(11):947-953
One of the important tasks in Mechanical Engineering is to increase the safety of the vehicle and decrease its production
costs. This task is typically solved by means of Multiobjective Optimization, which formulates the problem as a mapping from
the space of design variables to the space of target criteria and tries to find an optimal region in these multidimensional
spaces. Due to high computational costs of numerical simulations, the sampling of this mapping is usually very sparse and
scattered. Combining design of experiments methods, metamodeling, new interpolation schemes and innovative graphics methods,
we enable the user to interact with simulation parameters, optimization criteria, and come to a new interpolated crash result
within seconds. We denote this approach as Simulated Reality, a new concept for the interplay between simulation, optimization
and interactive visualization. In this paper we show the application of Simulated Reality for solution of real life car design
optimization problems.
相似文献
Lialia NikitinaEmail: |
34.
Igor V. Konnov 《Networks and Spatial Economics》2009,9(4):505-524
We consider several equilibrium formulations for the problem of managing spatially distributed auction markets of a homogeneous
commodity, which are joined by transmission lines in a network. At each market, traders and buyers are determined by their
price functions and choose their offer/bid values. We present equivalent variational inequality, optimization, and saddle
point formulations of this problem. The corresponding models possess a special structure of constraint and cost functions
and lead to different decomposition schemes. We propose proximal and splitting type methods and discuss their properties and
preliminary computational results. 相似文献
35.
Igor Garcia Ballhausen Sampaio José Viterbo Joris Guerin 《Computational Intelligence》2023,39(3):415-432
Object detection (OD) is used for visual quality control in factories. Images that compose training datasets are often collected directly from the production line and labeled with bounding boxes manually. Such data represent well the inference context but might lack diversity, implying a risk of overfitting. To address this issue, we propose a dataset construction method based on an automated pipeline, which receives a CAD model of an object and returns a set of realistic synthetic labeled images (code publicly available). Our approach can be easily used by non-expert users and is relevant for industrial applications, where CAD models are widely available. We performed experiments to compare the use of datasets obtained by the two different ways—collecting and labeling real images or applying the proposed automated pipeline—in the classification of five different industrial parts. To ensure that both approaches can be used without deep learning expertise, all training parameters were kept fixed during these experiments. In our results, both methods were successful for some objects but failed for others. However, we have shown that the combined use of real and synthetic images led to better results. This finding has the potential to make industrial OD models more robust to poor data collection and labeling errors, without increasing the difficulty of the training process. 相似文献
36.
Poly(vinylbenzyl trimethyl ammonium chloride) (PVT) exhibits functional properties, which have generated interest in the fabrication of PVT and composite films. New electrochemical strategies have been utilized for the deposition of PVT-zirconia composites. The problems, related to the electrodeposition of strong polyelectrolytes, such as PVT, were addressed by the development of charge compensation mechanisms. The deposition strategies involved electrophoretic cathodic deposition (EPD) of PVT and EPD or electrochemical synthesis of zirconia. The proof of concept investigations involved deposition yield studies under different conditions, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and electron microscopy studies. The electrochemical strategies can be used for electrodeposition of various composites, utilizing the properties of functional polymers and inorganic materials. 相似文献
37.
Igor Solodov Markus Rahammer Nikolai Gulnizkij Marc Kreutzbruck 《Journal of Nondestructive Evaluation》2016,35(3):48
A selective acoustic activation of defects based on the concept of local defect resonance enables to enhance considerably the intensity of defect vibrations and makes it possible to reduce the input acoustic powers to the levels permissible for noncontact nondestructive inspection. Since for cm-size defects in composite materials, the LDR frequencies lie in the low kHz-range, the resonant noncontact activation shifts to an audible frequency range and can be provided by conventional sonic equipment. In this paper, the feasibility of the resonant noncontact inspection is validated for the most “problematic” methodologies of nonlinear, thermosonic and shearosonic NDE that usually require an elevated acoustic power and, therefore, a reliable contact between the specimen and the transducer. In contrast, the noncontact versions developed employ commercial loudspeakers which can simultaneously insonify large areas and be applied for a contactless sonic inspection of different materials and various scale components. 相似文献
38.
The 24-H Knowledge Factory facilitates collaboration between geographically and temporally distributed teams. The teams themselves
form a strategic partnership whose joint efforts contribute to the completion of a project. Project-related tasks are likewise
distributed, allowing tasks to be completed on a continuous basis, regardless of the constraints of any one team’s working
hours. However, distributing a single task between multiple teams necessitates a handoff process, where one team’s development
efforts and task planning are communicated from one team ending their shift to the next that will continue the effort. Data
management is, therefore, critical to the success of this business model. Efficiency in data management is achieved through
a strategic leveraging of key tools, models, and concepts. 相似文献
39.
Explanation and reliability of prediction models: the case of breast cancer recurrence 总被引:1,自引:1,他引:0
Erik ?trumbelj Zoran Bosni? Igor Kononenko Branko Zakotnik Cvetka Gra?i? Kuhar 《Knowledge and Information Systems》2010,24(2):305-324
In this paper, we describe the first practical application of two methods, which bridge the gap between the non-expert user
and machine learning models. The first is a method for explaining classifiers’ predictions, which provides the user with additional
information about the decision-making process of a classifier. The second is a reliability estimation methodology for regression
predictions, which helps the users to decide to what extent to trust a particular prediction. Both methods are successfully
applied to a novel breast cancer recurrence prediction data set and the results are evaluated by expert oncologists. 相似文献
40.