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1.
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: |
2.
This paper revisits the problem of wireframe rendering, which, at first, appears to be an easily solved problem. However, the conventional solution is inefficient and does not result in high-quality images. Recently, graphics hardware programming has been employed to achieve high-quality solid line rendering. In this paper, we present a simpler and faster technique for wireframe rendering based on texture mapping. Our technique does not require (but can benefit from) graphics hardware programming and thus can be easily integrated into existing rendering engines, while resulting in fast, accurate, high-quality, anti-aliased, and still versatile, wireframe drawing. For topologically structured meshes, our approach allows the rendering of wireframe decoupled from the underlying mesh, making possible the rendering of original wireframes on top of decimated meshes. 相似文献
3.
Increased manufacturing costs are forcing U.S. manufacturing firms to send their operations off shore. Such business practices are greatly impacting the vitality of small and medium manufacturers (SMMs) in the U.S. economy. This article intends to advance the notion of the need for a methodology for assessment, improvement, and sustainability of intra‐ and inter‐enterprise system performance along the technology–product development life cycle. The aims of this article are to: (1) provide an overview of the technology–product development process; (2) document the different states of manufacturing technology readiness levels; (3) present an overview of prior methodologies reported on the subject in the published literature; and (4) establish a road map for assessment, improvement, and sustainability of intra‐ and inter‐enterprise system performance along the path of the technology–product development life cycle. A notion is advanced about the readiness of SMMs with respect to assessment, improvement, and sustainability of intra‐ and inter‐enterprise system performance. A road map is outlined for the deployment of a methodology to address the issues across the supply chain. © 2007 Wiley Periodicals, Inc. 相似文献
4.
Tomasz Urbanowicz Anna Olasiska-Winiewska Marcin Gadki Micha Michalak Mateusz Sochacki Anita Weclewska Dominika Zalas Waldemar Bobkowski Marek Jemielity 《International journal of molecular sciences》2022,23(20)
Neutrophils play a significant role in immune and inflammatory reactions. The preoperative inflammatory activation may have a detrimental effect on postoperative outcomes. The aim of the study was to investigate the relation between preoperative hematological indices on postoperative complications’ risk in pediatric cardiac congenital surgery. The retrospective single center analysis included 93 pediatric patients (48 (65%) males and 45 (35%) females), mean age of 7 (3–30) months referred for cardiac surgery in cardiopulmonary bypass due to functional single ventricle disease (26 procedures), shunts lesions (40 procedures) and cyanotic disease (27 procedures). Among simple hematological indices, the receiver-operating-characteristic curve showed that a neutrophil count below 2.59 K/uL was found as an optimal cut-off point for predicting postoperative atrioventricular block following pediatric cardiac surgery (AUC = 0.845, p < 0.0001) yielding a sensitivity of 100% and a specificity of 65.62%. Preoperative values of neutrophil count below 2.59 K/uL in whole blood analysis can be regarded as a predictive factor (AUC = 0.845, p < 0.0001) for postoperative atrioventricular block in pediatric cardiac surgery. 相似文献
5.
Daniel Alexander Bizjak Lucas John Lynn Matits Alisa Uhl Sebastian Victor Waldemar Schulz Jana Schellenberg Johannes Peifer Wilhelm Bloch Manfred Weiß Beate Grüner Hendrik Bracht Jürgen Michael Steinacker Marijke Grau 《International journal of molecular sciences》2022,23(23)
Hematological and hemorheological parameters are known to be altered in COVID-19; however, the value of combined monitoring in order to deduce disease severity is only scarcely examined. A total of 44 acute SARS-CoV-2-infected patients (aCOV) and 44 age-matched healthy controls (Con) were included. Blood of aCOV was sampled at admission (T0), and at day 2 (T2), day 5 (T5), day 10 (T10), and day 30 (T30) while blood of Con was only sampled once. Inter- and intra-group differences were calculated for hematological and hemorheological parameters. Except for mean cellular volume and mean cellular hemoglobin, all blood cell parameters were significantly different between aCOV and Con. During the acute disease state (T0–T5), hematological and hemorheological parameters were highly altered in aCOV; in particular, anemic conditions and increased immune cell response/inflammation, oxidative/nitrosative stress, decreased deformability, as well as increased aggregation, were observed. During treatment and convalescence until T30, almost all abnormal values of aCOV improved towards Con values. During the acute state of the COVID-19 disease, the hematological, as well as the hemorheological system, show fast and potentially pathological changes that might contribute to the progression of the disease, but changes appear to be largely reversible after four weeks. Measuring RBC deformability and aggregation, as well as oxidative stress induction, may be helpful in monitoring critically ill COVID-19 patients. 相似文献
6.
Anna Sykua Adriana Nowak Eugenio Garribba Aliaksandr Dzeikala Magdalena Rowiska-yrek Justyna Czerwiska Waldemar Maniukiewicz Elbieta odyga-Chruciska 《International journal of molecular sciences》2023,24(1)
The three Schiff base ligands, derivatives of hesperetin, HHSB (N-[2,3-dihydro-5,7-dihydroxy-2-(3-hydroxy-4-methoxyphenyl)chromen-4-ylidene]isonicotinohydrazide), HIN (N-[2,3-dihydro-5,7-dihydroxy-2-(3-hydroxy-4-methoxyphenyl)chromen-4-ylidene]benzhydrazide) and HTSC (N-[2,3-dihydro-5,7-dihydroxy-2-(3-hydroxy-4-methoxyphenyl)chromen-4-ylidene]thiosemicarbazide) and their copper complexes, CuHHSB, CuHIN, and CuHTSC were designed, synthesized and analyzed in terms of their spectral characterization and the genotoxic activity. Their structures were established using several methods: elemental analysis, FT-IR, UV-Vis, EPR, and ESI-MS. Spectral data showed that in the acetate complexes the tested Schiff bases act as neutral tridentate ligand coordinating to the copper ion through two oxygen (or oxygen and sulphur) donor atoms and a nitrogen donor atom. EPR measurements indicate that in solution the complexes keep their structures with the ligands remaining bound to copper(II) in a tridentate fashion with (O–, N, Oket) or (O–, N, S) donor set. The genotoxic activity of the compounds was tested against model tumour (HeLa and Caco-2) and normal (LLC-PK1) cell lines. In HeLa cells the genotoxicity for all tested compounds was noticed, for HHSB and CuHHSB was the highest, for HTSC and CuHTSC–the lowest. Generally, Cu complexes displayed lower genotoxicity to HeLa cells than ligands. In the case of Caco-2 cell line HHSB and HTSC induced the strongest breaks to DNA. On the other side, CuHHSB and CuHTSC induced the highest DNA damage against LLC-PK1. 相似文献
7.
Arun Garg Thomas Waters Jay Kapellusch Waldemar Karwowski 《International Journal of Industrial Ergonomics》2014
The objective of this paper was to perform a comprehensive review of psychophysically determined maximum acceptable pushing and pulling forces. Factors affecting pushing and pulling forces are identified and discussed. Recent studies show a significant decrease (compared to previous studies) in maximum acceptable forces for males but not for females when pushing and pulling on a treadmill. A comparison of pushing and pulling forces measured using a high inertia cart with those measured on a treadmill shows that the pushing and pulling forces using high inertia cart are higher for males but are about the same for females. It is concluded that the recommendations of Snook and Ciriello (1991) for pushing and pulling forces are still valid and provide reasonable recommendations for ergonomics practitioners. Regression equations as a function of handle height, frequency of exertion and pushing/pulling distance are provided to estimate maximum initial and sustained forces for pushing and pulling acceptable to 75% male and female workers. 相似文献
8.
Barbara Wachowicz Koryna Lewandowska Anna Popek Waldemar Karwowski Tadeusz Marek 《人机工程学与制造业中的人性因素》2016,26(2):266-284
The primary purpose of this paper is to discuss the role of empathy in the design of advanced systems in manufacturing and service industries in order to ensure suitable working conditions for employees from the social and technological point of view. The origins and components of empathy are briefly reviewed. The neural underpinnings of three components of empathy, including cognitive, emotional, and behavioral aspects, are considered in the context of human–human and human–machine interactions, as well as design of working environments. Finally, the potential advantages of applying empathy‐related knowledge to the design and development of human‐centered technology are discussed. 相似文献
9.
Zofia Lisiewska Piotr Gębczyński Waldemar Kmiecik 《European Food Research and Technology》2007,226(1-2):25-31
The investigation included kale, New Zealand spinach and spinach. The evaluation covered the raw material; the raw material
after blanching; the raw material after cooking; and frozen products prepared for consumption after 0, 4, 8 and 12 months
of refrigerated storage. Both the traditional method of freezing (blanching before freezing) and the modified method of freezing
(cooked before freezing) were used in the experiment, as well as two storage temperatures, T = −20 °C and T = −30 °C. The content of chlorophylls in fresh kale was four times that in New Zealand spinach and 1.5 times that in spinach.
With the exception of New Zealand spinach, blanching and cooking significantly reduced the content of chlorophylls. In kale
products prepared for consumption, the content of chlorophylls decreased in each successive stage of the investigation. In
products of New Zealand spinach and spinach, the losses were usually not significant. After 12 months of refrigerated storage,
frozen kale products prepared for consumption retained 52–65% of total chlorophylls compared with the content in the raw material;
products of New Zealand spinach and spinach retained 66–71%. In kale and New Zealand spinach, the content of chlorophyll a
decreased more rapidly than that of chlorophyll b, while in spinach the converse was true. The kale products obtained using
the modified method contained more chlorophylls, while in the two spinach species their content was lower. The lower storage
temperature resulted in a higher retention of chlorophylls in vegetables. 相似文献
10.
Synthesis and Characterization of Pyridine Compounds for Amperometric Measurements of Leukocyte Esterase 下载免费PDF全文
Douglas Hanson Travis Menard Teresa Blazek Prof. Dr. Stanton McHardy Prof. Dr. Waldemar Gorski 《Chembiochem : a European journal of chemical biology》2018,19(14):1488-1491
We introduce a new class of substrates (compounds I – III ) for leukocyte esterase (LE) that react with LE yielding anodic current in direct proportion to LE activity. The kinetic constants Km and kcat for the enzymatic reactions were determined by amperometry at a glassy carbon electrode. The binding affinity of I – III for LE was two orders of magnitude better than that of existing optical LE substrates. The specificity constant kcat/Km was equal to 2.7, 3.8, and 5.8×105 m ?1 s?1 for compounds containing the pyridine ( I ), methoxypyridine ( II ), and (methoxycarbonyl)pyridine ( III ), respectively, thus showing an increase in catalytic efficiency in this order. Compound III had the lowest octanol/water partition coefficient (log p=0.33) along with the highest topological surface area (tPSA=222 Å2) and the best aqueous solubility (4.0 mg mL?1). The average enzymatic activity of LE released from a single leukocyte was equal to 4.5 nU when measured with compound III . 相似文献